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Sample records for calculated oxygen fugacity

  1. Calculation of Oxygen Fugacity in High Pressure Metal-Silicate Experiments and Comparison to Standard Approaches

    NASA Technical Reports Server (NTRS)

    Righter, K.; Ghiorso, M.

    2009-01-01

    Calculation of oxygen fugacity in high pressure and temperature experiments in metal-silicate systems is usually approximated by the ratio of Fe in the metal and FeO in the silicate melt: (Delta)IW=2*log(X(sub Fe)/X(sub FeO)), where IW is the iron-wustite reference oxygen buffer. Although this is a quick and easy calculation to make, it has been applied to a huge variety of metallic (Fe- Ni-S-C-O-Si systems) and silicate liquids (SiO2, Al2O3, TiO2, FeO, MgO, CaO, Na2O, K2O systems). This approach has surely led to values that have little meaning, yet are applied with great confidence, for example, to a terrestrial mantle at "IW-2". Although fO2 can be circumvented in some cases by consideration of Fe-M distribution coefficient, these do not eliminate the effects of alloy or silicate liquid compositional variation, or the specific chemical effects of S in the silicate liquid, for example. In order to address the issue of what the actual value of fO2 is in any given experiment, we have calculated fO2 from the equilibria 2Fe (metal) + SiO2 (liq) + O2 = Fe2SiO4 (liq).

  2. Oxygen fugacities directly measured in magmatic gases.

    PubMed

    Sato, M; Wright, T L

    1966-09-02

    An electrochemical device was used to measure the fugacity of oxygen (fo(o2)) in holes drilled through the crust of Makaopuhi lava lake, Kilauea Volcano, Hawaii. Results obtained within 6 months of the lake formation show that log fo(o2) normally varies linearly with the reciprocal of the absolute temperature, and that chemical changes occurring in the cooling tholeiitic basalt are reflected in the fo(o2) values measured in the holes.

  3. Oxygen fugacities directly measured in magmatic gases

    USGS Publications Warehouse

    Sato, M.; Wright, T.L.

    1966-01-01

    An electrochemical device was used to measure the fugacity of oxygen (fO2) in holes drilled through the crust of Makaopuhi lava lake, Kilauea Volcano, Hawaii. Results obtained within 6 months of the lake formation show that log fO2 normally varies linearly with the reciprocal of the absolute temperature, and that chemical changes occurring in the cooling tholeiitic basalt are reflected in the fO2 values measured in the holes.

  4. Oxygen fugacity and piston cylinder capsule assemblies

    NASA Astrophysics Data System (ADS)

    Jakobsson, S.

    2011-12-01

    A double capsule assembly designed to control oxygen fugacity in piston cylinder experiments has been tested at 1200 °C and 10 kbar. The assembly consists of an outer Pt-capsule containing a solid buffer (Ni-NiO or Co-CoO plus H2O) and an inner AuPd-capsule containing the sample, H2O and a Pt-wire. To prevent direct contact with the buffer phases the AuPd-capsule is embedded in finely ground Al2O3 along with some coarser, fractured Al2O3 facilitating fluid inclusion formation. No water loss is observed in the sample even after 48 hrs but a slight increase in water content is observed in longer duration runs due to oxygen and hydrogen diffusion into the AuPd-capsule. Carbon from the furnace also diffuses through the outer Pt-capsule but reacts with H2O in the outer capsule to form CO2 and never reaches the inner capsule. Oxygen fugacity of runs in equilibrium with the Ni-NiO and Co-CoO buffers was measured by analyzing the Fe content of the Pt-wire in the sample1 and by analyzing Fe dissolved in the AuPd capsule2. The second method gives values that are in good agreement with established buffer whereas results from the first method are one half to one log units higher than the established values. References 1. E. Medard, C. A. McCammon, J. A. Barr, T. L. Grove, Am. Mineral. 93, 1838 (2008). 2. J. Barr, T. Grove, Contrib. Mineral. Petrol. 160, 631 (2010)

  5. The oxidation state of europium as an indicator of oxygen fugacity. [lunar and terrestrial rocks, achondritic meteorites

    NASA Technical Reports Server (NTRS)

    Drake, M. J.

    1975-01-01

    Empirical oxygen barometers based on Eu(2+)/Eu(3+) ratios in plagioclase feldspar and magmatic liquid were developed using Philpott's (1970) approach and the experimental data of Drake (1972). Oxygen fugacities calculated on the basis of Eu(2+)/Eu(3+) ratios for terrestrial basalts cluster tightly around 10 to the negative seventh power. Oxygen fugacities for Apollo 11 and 12 lunar ferrobasalts cluster tightly around 10 to the negative 12.7 power. Calculated oxygen fugacities for achondritic meteorites are lower than for lunar samples by several orders of magnitude.

  6. Iron isotope fractionation and the oxygen fugacity of the mantle.

    PubMed

    Williams, Helen M; McCammon, Catherine A; Peslier, Anne H; Halliday, Alex N; Teutsch, Nadya; Levasseur, Sylvain; Burg, Jean-Pierre

    2004-06-11

    The oxygen fugacity of the mantle exerts a fundamental influence on mantle melting, volatile speciation, and the development of the atmosphere. However, its evolution through time is poorly understood. Changes in mantle oxidation state should be reflected in the Fe3+/Fe2+ of mantle minerals, and hence in stable iron isotope fractionation. Here it is shown that there are substantial (1.7 per mil) systematic variations in the iron isotope compositions (delta57/54Fe) of mantle spinels. Spinel delta57/54Fe values correlate with relative oxygen fugacity, Fe3+/sigmaFe, and chromium number, and provide a proxy of changes in mantle oxidation state, melting, and volatile recycling.

  7. Oxygen buffering of Kilauea volcanic gases and the oxygen fugacity of Kilauea basalt

    NASA Astrophysics Data System (ADS)

    Gerlach, T. M.

    1993-02-01

    . This conclusion challenges the common assumption that volcanic gases are released from lava in a state of chemical equilibrium and then continue equilibrating homogeneously with falling temperature until reaction rates are unable to keep pace with cooling. No evidence is found, moreover, that certain gas species are kinetically more responsive and able to equilibrate down to lower temperatures than those of the last gas/lava oxygen exchange. Homogeneous reaction rates in the gas phase are apparently slow compared to the time it took for the gases to move from the last site of gas/lava equilibration to the site of collection. An earlier set of data for higher temperature CO 2-rich Type I volcanic gases, which come from sustained summit lava lake eruptions supplied by magma that experienced substantially shorter periods of crustal storage, shows fO2 buffering by oxygen transfer up to 1185°C. Oxygen fugacity measurements in drill holes into ponded lava flows suggest that buffering by oxygen transfer may control the fO2 of residual gases down to several hundred degrees below the solidus in the early stages of cooling. Although the details of the fO2 buffering mechanisms for oxygen transfer are unknown, the fact that fO2 buffering is effective from molten to subsolidus conditions suggests that the reaction mechanisms must change with cooling as the reactants change from predominantly melt, to melt plus crystals, to glass plus crystals. Mass balance calculations suggest that redox reactions between the gas and ferrous/ferric iron in the lava are plausible mechanisms for the oxygen transfer and that the fO2 of the gases is buffered by sliding ferrous/ferric equilibria in the erupting lavas. Contrary to expectations based on models predicting the oxidation of basalt by H 2 and CO escape during crustal storage, CO 2-rich Type I gases and CO 2-poor Type II gases have identical oxygen fugacities despite greatly different crustal storage and degassing histories. Volcanic gas data

  8. Oxygen Fugacity of Abyssal Peridotites Along the Gakkel Ridge

    NASA Astrophysics Data System (ADS)

    Said, M.; Birner, S.; Cottrell, E.

    2015-12-01

    The oxygen budget of the Earth's mantle is important in understanding how our planet evolves chemically over time. The Gakkel Ridge is the world's slowest spreading ridge [1], and exposes peridotites along its axis that record the activity of oxygen in the upper mantle. Our samples comprise relatively fertile lherzolites and harzburgites (Cr#=0.13-0.17, 3.1-8.3% modal cpx [2]) as well as refractory harzburgites (Cr#=0.43-0.55, 0.2-1.0% modal cpx [2]). Using spinel peridotite oxygen barometry [3], we calculated the oxygen fugacity (fO2) of a suite of 10 peridotites from the Gakkel Ridge in order to investigate how melt processes affect the oxygen budget of the Earth's interior. We show that the low-Cr# lherzolites and harzburgites range from -0.1 to +0.6 log units relative to the QFM buffer, consistent with the global abyssal peridotite array, whereas high-Cr# refractory harzburgites have low fO2 values, ranging from -0.7 to -2.7 log units below QFM, with the most refractory samples falling significantly lower than the global array. Because D'Errico et al. (submitted) interprets the refractory samples as recording ancient melt extraction, the low fO2 recorded by these samples may originate in the geologic past, perhaps even in a different tectonic setting. While LREE enrichment in the refractory harzburgites [2] provides evidence for refertilization by an infiltrating melt that could have recently imprinted reducing conditions, we see no corresponding increase in TiO2 content in the spinels, which weakens this hypothesis. Further research on additional refractory harzburgites is needed to constrain whether the reduced nature of these samples is telling us something about the effect of extreme melt extraction on fO2 at ridges, or whether these samples record a unique history that obscures processes operating at ridges today. [1] Coakley and Cochran, EPSL (1998), [2] D'Errico et al., submitted, [3] Bryndzia and Wood, American Journal of Science (1990)

  9. Oxygen fugacity control in piston-cylinder experiments

    NASA Astrophysics Data System (ADS)

    Jakobsson, Sigurdur

    2012-09-01

    The main goal of this study was to develop and test a capsule assembly for use in piston-cylinder experiments where oxygen fugacity could be controlled in the vicinity of the QFM buffer without H2O loss or carbon contamination of the sample material. The assembly consists of an outer Pt-capsule containing a solid buffer (Ni-NiO or Co-CoO) plus H2O and an inner AuPd-capsule, containing the sample, H2O and a Pt-wire. No H2O loss is observed from the sample, even after 48 h, but a slight increase in H2O content is found in longer runs due to oxygen and hydrogen diffusion into the AuPd-capsule. Oxygen fugacity of runs in equilibrium with the Ni-NiO (NNO) and Co-CoO (CoCO) buffers was measured by analyzing Fe dissolved in the Pt-wire and in the AuPd-capsule. The second method gives values that are in good agreement with established buffer values, whereas results from the first method are one half to one log units higher than the established values.

  10. Oxygen buffering of Kilauea volcanic gases and the oxygen fugacity of Kilauea basalt

    USGS Publications Warehouse

    Gerlach, T.M.

    1993-01-01

    challenges the common assumption that volcanic gases are released from lava in a state of chemical equilibrium and then continue equilibrating homogeneously with falling temperature until reaction rates are unable to keep pace with cooling. No evidence is found, moreover, that certain gas species are kinetically more responsive and able to equilibrate down to lower temperatures than those of the last gas/lava oxygen exchange. Homogeneous reaction rates in the gas phase are apparently slow compared to the time it took for the gases to move from the last site of gas/lava equilibration to the site of collection. An earlier set of data for higher temperature CO2-rich Type I volcanic gases, which come from sustained summit lava lake eruptions supplied by magma that experienced substantially shorter periods of crustal storage, shows fO2 buffering by oxygen transfer up to 1185??C. Oxygen fugacity measurements in drill holes into ponded lava flows suggest that buffering by oxygen transfer may control the fO2 of residual gases down to several hundred degrees below the solidus in the early stages of cooling. Although the details of the fO2 buffering mechanisms for oxygen transfer are unknown, the fact that fO2 buffering is effective from molten to subsolidus conditions suggests that the reaction mechanisms must change with cooling as the reactants change from predominantly melt, to melt plus crystals, to glass plus crystals. Mass balance calculations suggest that redox reactions between the gas and ferrous/ferric iron in the lava are plausible mechanisms for the oxygen transfer and that the fO2 of the gases is buffered by sliding ferrous/ferric equilibria in the erupting lavas. Contrary to expectations based on models predicting the oxidation of basalt by H2 and CO escape during crustal storage, CO2-rich Type I gases and CO2-poor Type II gases have identical oxygen fugacities despite greatly different crustal storage and degassing histories. Volcanic gas data give a tightly co

  11. The Relationship Between Clinopyroxene Fe3+ Content and Oxygen Fugacity

    NASA Technical Reports Server (NTRS)

    McCanta, M. C.; Rutherford, M. J.; Dyar, M. J.; Delaney, J. S.

    2004-01-01

    The intrinsic oxygen fugacity (fO2) imposed on a magma has the ability to influence the crystallization sequence of the melt, as well as the composition of the resulting minerals. fO2 is an easily controlled parameter in the lab, either through gas-mixing equilibria or with a solid-state buffer assemblage. In nature, the fO2 of a closed system is imposed on the system internally through multivalent equilibria involving the phenocryst-melt assemblage. This results in a characteristic oxidation state. The physical parameter used to quantify oxidation state is oxygen fugacity. Iron is the only major rock forming element in basaltic melts to exist in multiple valence states and, therefore, it is commonly used to assess fO2. Traditional methods to quantify fO2 utilize the ferric content of glasses or coexisting Fe-Ti oxides. However, many rocks, such as the Martian meteorites, do not contain the necessary phases or have oxides which have suffered reequilibration, thereby rendering them unmeasureable by current techniques. For these rocks, new methods, utilizing other phases are needed. Mafic minerals have Fe(3+)/SigmaFe ratios that are a function of two factors: 1) crystal chemistry and 2) their intrinsic fO2 during crystallization. Olivine and orthopyroxene, for example, have steric constraints on the extent to which Fe(3+) can be incorporated in their structures, and may not record changes in magmatic fO2 in a way that can easily be measured. The chemistry of clinopyroxene, however, allows for extensive incorporation of Fe(3+) in its crystal structure, making it a potentially useful oxybarometer. To date, there have been few, if any, systematic experimental studies of the variation of the Fe(3+)/SigmaFe ratio as a function of fO2 in clinopyroxene. This study seeks to address this lack of data.

  12. Control and monitoring of oxygen fugacity in piston cylinder experiments

    NASA Astrophysics Data System (ADS)

    Matjuschkin, Vladimir; Brooker, Richard A.; Tattitch, Brian; Blundy, Jon D.; Stamper, Charlotte C.

    2015-01-01

    We present a newly developed capsule design that resolves some common problems associated with the monitoring and control of oxygen fugacity ( fO2) in high-pressure piston cylinder experiments. The new fO2 control assembly consists of an AuPd outer capsule enclosing two inner capsules: one of AuPd capsule containing the experimental charge (including some water), and the other of Pt containing a solid oxygen buffer plus water. The inner capsules are separated by crushable alumina. The outer capsule is surrounded by a Pyrex sleeve to simultaneously minimise hydrogen loss from the cell and carbon infiltration from the graphite furnace. Controlled fO2 experiments using this cell design were carried out at 1.0 GPa and 1,000 °C. We used NiPd, CoPd and (Ni, Mg)O fO2 sensors, whose pressure sensitivity is well calibrated, to monitor the redox states achieved in experiments buffered by Re-ReO2, Ni-NiO and Co-CoO, respectively. Results for the fO2 sensors are in good agreement with the intended fO2 established by the buffer, demonstrating excellent control for durations of 24-48 h, with uncertainties less than ± 0.3 log bar units of fO2.

  13. Oxygen Fugacity of the Martian Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium

    NASA Astrophysics Data System (ADS)

    Musselwhite, D. S.; Jones, J. H.; Shearer, C.

    2004-03-01

    We present results from experimental calibration of the pigeonite/melt oxybarometer. Application of these results to martian basalts gives a range of oxygen fugacities similar, but not identical to those determined from Fe-Ti oxides.

  14. The effect of oxygen fugacity on the solubility of carbon-oxygen fluids in basaltic melt

    NASA Technical Reports Server (NTRS)

    Pawley, Alison R.; Holloway, John R.; Mcmillan, Paul F.

    1992-01-01

    The solubility of CO2-CO fluids in a midocean ridge basalt have been measured at 1200 C, 500-1500 bar, and oxygen fugacities between NNO and NNO-4. In agreement with results of previous studies, the results reported here imply that, at least at low pressures, CO2 dissolves in basaltic melt only in the form of carbonate groups. The dissolution reaction is heterogeneous, with CO2 molecules in the fluid reacting directly with reactive oxygens in the melt to produce CO3(2-). CO, on the other hand, is insoluble, dissolving neither as carbon, molecular CO, nor CO3(2-). It is shown that, for a given pressure and temperature, the concentration of dissolved carbon-bearing species in basaltic melt in equilibrium with a carbon-oxygen fluid is proportional to the mole fraction of CO2 in the fluid, which is a function of fO2. At low pressures CO2 solubility is a linear function of CO2 fugacity at constant temperatures.

  15. Technical Update: Johnson Space Center system using a solid electrolytic cell in a remote location to measure oxygen fugacities in CO/CO2 controlled-atmosphere furnaces

    NASA Technical Reports Server (NTRS)

    Jurewicz, A. J. G.; Williams, R. J.; Le, L.; Wagstaff, J.; Lofgren, G.; Lanier, A.; Carter, W.; Roshko, A.

    1993-01-01

    Details are given for the design and application of a (one atmosphere) redox-control system. This system differs from that given in NASA Technical Memorandum 58234 in that it uses a single solid-electrolytic cell in a remote location to measure the oxygen fugacities of multiple CO/CO2 controlled-atmosphere furnaces. This remote measurement extends the range of sample-furnace conditions that can be measured using a solid-electrolytic cell, and cuts costs by extending the life of the sensors and by minimizing the number of sensors in use. The system consists of a reference furnace and an exhaust-gas manifold. The reference furnace is designed according to the redox control system of NASA Technical Memorandum 58234, and any number of CO/CO2 controlled-atmosphere furnaces can be attached to the exhaust-gas manifold. Using the manifold, the exhaust gas from individual CO/CO2 controlled atmosphere furnaces can be diverted through the reference furnace, where a solid-electrolyte cell is used to read the ambient oxygen fugacity. The oxygen fugacity measured in the reference furnace can then be used to calculate the oxygen fugacity in the individual CO/CO2 controlled-atmosphere furnace. A BASIC computer program was developed to expedite this calculation.

  16. Using Vanadium in Spinel as a Sensor of Oxygen Fugacity in Meteorites: Applications to Mars, Vesta, and Other Asteroids

    NASA Astrophysics Data System (ADS)

    Righter, K.; Sutton, S.; Danielson, L.; Pando, K.; Le, L.; Newville, M.

    2009-03-01

    Some meteorites do not contain mineral assemblages required to apply traditional oxy-barometers. Here we introduce a technique using vanadium X-ray absorption features in spinels to characterize the oxygen fugacity of meteoritic dunites, pyroxenites, and chondrites.

  17. 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.

  18. Oxygen buffering of Kilauea volcanic gases and the oxygen fugacity of Kilauea basalt

    SciTech Connect

    Gerlach, T.M. )

    1993-02-01

    Volcanic gases collected during episode 1 of the Puu Oo eruption along the east rift zone of Kilauea Volcano, Hawaii, have uniform C-O-H-S-Cl-F compositions that are sharply depleted in CO[sub 2]. The CO[sub 2]-poor gases are typical of Type II volcanic gases (GERLACH and GRAEBER, 1985) and were emitted from evolved magma stored for a prolonged period of time in the east rift zone after releasing CO[sub 2]-rich gases during an earlier period of temporary residence in the summit magma chamber. The samples are remarkably free of contamination by atmospheric gases and meteoric water. Thermodynamic evaluation of the analytical data shows that the episode 1 gases have equilibrium compositions appropriate for temperatures between 935 and 1032[degrees]C. Open- and closed-system equilibrium models of species distributions for the episode 1 gases show unequivocally that coexisting lavas buffered the gas oxygen fugacities during cooling. These models indicate that the F[sub o[sub 2

  19. Electrochemical manipulation of apparent oxygen fugacity in a piston cylinder apparatus

    NASA Astrophysics Data System (ADS)

    Kavner, A.; Newville, M.; Sutton, S.; Walker, D.; Wheeler, K.

    2002-12-01

    Phase stability of mineral assemblages and their physical properties, especially transport properties, are influenced by oxygen fugacity. Redox effects in earth and planetary systems at high pressure include setting of ferric/ferrous iron ratios [controlling the electrical conductivity of crustal and mantle materials] and possible chemical reactions at the Earth's core-mantle boundary. Experimental controls of oxygen fugacity in high-pressure devices have been limited to discrete electrochemical potentials set by buffers such as C-CO, Ni-NiO, and QFM. By contrast, an electric field applied across a silicate sample inside a piston cylinder apparatus establishes a smoothly-varying electrochemical gradient that can be quantified and tied to the oxygen fugacity scale through synchrotron microXANES of polyvalent V and Fe within the silicate. Fugacity gradient samples were synthesized in a modified Boyd-England piston-cylinder configuration. Platinum electrodes were placed at both ends of a 2-mm cylinder of basaltic composition silicate glass containing ~5% Fe and ~2% V. The sample assembly was surrounded by MgO ceramic, sheathed within a Mo faraday sleeve to insulate the sample from the AC field of the heater, and placed within a 0.5 inch diameter pressure vessel. The assembly was sintered at 800°C for 72 hours to eliminate porosity in the MgO capsule, and then heated to 1400°C for 23 hrs at 10 kbar. At high temperature, a 1V potential difference was applied across the electrodes via an external power supply. The sample was then quenched, potted in epoxy, and polished to a thickness of ~30 μm, and analyzed via optical and scanning electron microscopy. Vanadium, with oxidation states of 0 and +II to +V, was used as a chemical marker to evaluate the absolute value of the fO2 conditions across the silicate sample. Synchrotron-based microXANES techniques at GSECARS at the Advanced Photon Source in Argonne, IL were used to measure the pre-edge peak height at the vanadium

  20. Using vanadium in spinel as a sensor of oxygen fugacity in meteorites: Applications to Mars, Vesta, and other asteroids.

    SciTech Connect

    Righter, K.; Sutton, S.; Danielson, L.; Pando, K.; Le, L.; Newville, M.

    2009-03-23

    Some meteorites do not contain mineral assemblages required to apply traditional oxy-barometers. Here we introduce a technique using vanadium X-ray absorption features in spinels to characterize the oxygen fugacity of meteoritic dunites, pyroxenites, and chondrites. Igneous and metamorphic rocks commonly contain a mineral assemblage that allows oxygen fugacity to be calculated or constrained such as FeTi oxides, olivine-opx-spinel, or some other oxybarometer. Some rocks, however, contain a limited mineral assemblage and do not provide constraints on fO{sub 2} using mineral equilibria. Good examples of the latter are orthopyroxenites or dunites, such as diogenites, ALH 84001, chassignites, or brachinites. In fact it is no surprise that the fO{sub 2} of many of these samples is not well known, other than being 'reduced' and below the metal saturation value. In order to bridge this gap in our understanding, we have initiated a study of V in chromites in natural meteorite samples. Because the V pre-edge peak intensity and energy in chromites varies with fO{sub 2}, and this has been calibrated over a large fO{sub 2} range, we can apply this relation to rocks for which we otherwise have no fO{sub 2} constraints.

  1. Magmatic oxygen fugacity estimated using zircon-melt partitioning of cerium

    NASA Astrophysics Data System (ADS)

    Smythe, Duane J.; Brenan, James M.

    2016-11-01

    Using a newly-calibrated relation for cerium redox equilibria in silicate melts (Smythe and Brenan, 2015), and an internally-consistent model for zircon-melt partitioning of Ce, we provide a method to estimate the prevailing redox conditions during crystallization of zircon-saturated magmas. With this approach, oxygen fugacities were calculated for samples from the Bishop tuff (USA), Toba tuff (Indonesia) and the Nain plutonic suite (Canada), which typically agree with independent estimates within one log unit or better. With the success of reproducing the fO2 of well-constrained igneous systems, we have applied our Ce-in-zircon oxygen barometer to estimating the redox state of Earth's earliest magmas. Using the composition of the Jack Hills Hadean zircons, combined with estimates of their parental magma composition, we determined the fO2 during zircon crystallization to be between FMQ -1.0 to +2.5 (where FMQ is the fayalite-magnetite-quartz buffer). Of the parental magmas considered, Archean tonalite-trondhjemite-granodiorite (TTG) compositions yield zircon-melt partitioning most similar to well-constrained modern suites (e.g., Sano et al., 2002). Although broadly consistent with previous redox estimates from the Jack Hills zircons, our results provide a more precise determination of fO2, narrowing the range for Hadean parental magmas by more than 8 orders of magnitude. Results suggest that relatively oxidized magmatic source regions, similar in oxidation state to that of 3.5 Ga komatiite suites, existed by ∼4.4 Ga.

  2. Tracing Oxygen Fugacity in Asteroids and Meteorites Through Olivine Composition

    NASA Technical Reports Server (NTRS)

    Sunshine, J. M.; Bus, S. J.; Burbine, T. H.; McCoy, T. J.

    2005-01-01

    Olivine absorptions are known to dominate telescopic spectra of several asteroids. Among the meteorite collection, three groups (excluding Martian meteorites), the pallasites, brachinites, and R group chondrites are plausible analogs to olivine-rich asteroids in that they are dominated by olivine. These meteorite groups have distinct petrologic origins. The primitive achondrite brachinites (which include both depleted and undeleted subgroups) are products of relatively minor differentiation and evolved in oxidizing environments. R chondrites are also thought to have formed in high oxygen states, but are closely related to ordinary chondrites (yet with their own distinct compositions and oxygen isotopic signatures). In contrast, pallasites, widely thought to be mantle components from much more evolved bodies, formed in more reducing environments. Petrologic indicators that are identifiable in spectral data must be used in order to infer the petrologic history of asteroids from surveys of their actual population. As discussed below, olivine composition (e.g. Fa#) can provide key constraints in exploring the origin and significance of olivine dominated asteroids.

  3. 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

  4. Partitioning of palladium, iridium, and platinum between sulfide liquid and basalt melt: Effects of melt composition, concentration, and oxygen fugacity

    NASA Astrophysics Data System (ADS)

    Fleet, M. E.; Stone, W. E.; Crocket, J. H.

    1991-09-01

    The partitioning of Pd, Ir, and Pt between immiscible (Fe, Ni)-monosulfide liquid and basalt melt has been investigated at 1300°C and at low pressure over the concentration range 40 to 20,000 ppm platinum-group element(s) (PGE) in the sulfide liquid and at oxygen fugacities from the C-CO-CO2 to the wüstite-magnetite buffers. The experiments used sealed silica-glass tubes with internal oxygen buffers: PGE in glass were determined by radiochemical neutron activation analysis (RNAA). Partition coefficients (D) vary markedly with compositions of the sulfide liquid and silicate melt, increasing with decrease in oxygen fugacity, S, Fe, and possibly Ni, and with increase in total concentration of PGE. For 5 ppb PGE in the silicate melt and the iron-silica phase-fayalite (IQF) buffer, D(Pd) and D(Pt) are about 2 × 103, and D(Ir) is about 3 × 103; whereas, at the maximum concentration of PGE investigated, D(Pd) and D(Pt) are about 2 × 104, and D(Ir) is about 3 × 104. A single experiment confirms the marked fractionation of Pt from Pd predicted for partitioning with alloy in S-bearing and S-saturated silicate melts. The experimental D(PGE) values for low concentration of PGE are similar to D(PGE) calculated for many sulfide ore deposits, but are several orders of magnitude lower than calculated values for concordant sulfide PGE deposits in layered complexes.

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

    NASA Technical Reports Server (NTRS)

    Williams, R. J.; Mullins, O.

    1976-01-01

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

  6. SNC Oxygen Fugacity Recorded in Pyroxenes and its Implications for the Oxidation State of the Martian Interior: An Experimental and Analytical Study

    NASA Technical Reports Server (NTRS)

    McCanta, M. C.; Rutherford, M. J.

    2003-01-01

    Knowledge of the oxidation state of a magma is critical as it is one of the parameters which controls the nature and composition of the resulting crystals. In terrestrial magmatic systems, oxygen fugacity (fo2) is known to vary by over nine orders of magnitude. With variations of this magnitude, understanding the compositional differences, phase changes, and crystallization sequence variations, caused by the magma fo2, is essential in deciphering the origin of all igneous rocks. Magmatic oxidation state is of great importance in that it reflects the degree of oxidation of the source region and can provide insight into magmatic processes, such as metasomatism, degassing, and assimilation, which may have changed them. Carmichael [1991] argues that most magmas are unlikely to have their redox states altered from those of their source region. This assumption allows for estimation of the oxidation state of planetary interiors. Conversely, it is known that the fo2 of the magma can be affected by other processes, which occur outside of the source region and therefore, the oxidation state may record those too. Processes which could overprint source region fugacities include melt dehydrogenation or other volatile loss, water or melt infiltration, or assimilation of oxidized or reduced wallrock. Understanding which of these processes is responsible for the redox state of a magma can provide crucial information regarding igneous processes and other forces active in the region. The composition of the SNC basalts and their widely varying proposed oxidation states raise some interesting questions. Do the SNC meteorites have an oxidized or reduced signature? What was the oxygen fugacity of the SNC source region at the time of melt generation? Is the fugacity calculated for the various SNC samples the fugacity of the magma source region or was it overprinted by later events? Are there different oxidation states in the Martian interior or a single one? This proposal seeks to

  7. Diffusion of Redox-Sensitive Elements in Basalt at Different Oxygen Fugacities

    NASA Technical Reports Server (NTRS)

    Szumila, I.; Trail, D.; Danielson, L. R.

    2017-01-01

    The terrestrial planets and moons of our solar system have differentiated over a range of oxygen fugacity conditions. Basalts formed from magmas on the Earth cover a range of more oxidized states (from approximately IW (iron wustite) plus 2 to approximately FMQ (fayalite-magnetite-quartz) plus 3) than crustal rocks from Mars (IW to approximately IW plus 3), and basalts from the Moon are more reduced than both, ranging from IW to IW minus 2. The small body Vesta differentiated around IW minus 4. Characterization of redox sensitive elements' diffusivities will offer insight into behavior of these elements as a function of f (fugacity of) O2 for these planetary bodies. Here, we report a systematic study of the diffusion of redox-sensitive elements in basaltic melts with varying oxygen fugacities (fO2) for trace elements, V, Nb, W, Mo, La, Ce, Pr, Sm, Eu, Gd, Ta, and W. Since fO2 is an intensive variable that is different for the reservoirs of various planets and moons in our solar system, it is important to characterize how changes in redox states will affect diffusion. We conducted experiments in a piston cylinder device at 1300 degrees Centigrade and 1 gigapascal, at the University of Rochester and NASA Johnson Space Center. We buffered some experiments at Ru-RuO2 (FMQ plus 6.00), and conducted other experiments within either a graphite or Mo capsule, which corresponds to fO2s of either FMQ minus1.2, or FMQ minus 3.00, respectively. Characterizing the diffusivities of redox sensitive elements at different fO2s is important because some elements, like Eu, have varying valence states, such as Eu (sup 2 plus) and Eu (sup 3 plus). Differences in charge and ion radii may lead to differences in diffusivities within silicate melts. This could, lead to formation of a Eu anomaly by diffusion, the magnitude of which may be controlled by the fO2. Characterization of trace element diffusion is also important in understanding trace element fractionation. We found, during the

  8. The oxygen fugacity at which graphite or diamond forms from carbonate-bearing melts in eclogitic rocks

    NASA Astrophysics Data System (ADS)

    Stagno, V.; Frost, D. J.; McCammon, C. A.; Mohseni, H.; Fei, Y.

    2015-02-01

    The oxygen fugacity ( fO2) at which carbonate-bearing melts are reduced to either graphite or diamond in synthetic eclogite compositions has been measured in multi-anvil experiments performed at pressures between 3 and 7 GPa and temperatures between 800 and 1,300 °C using iron-iridium and iron-platinum alloys as sliding redox sensors. The determined oxygen fugacities buffered by the coexistence of elemental carbon and carbonate-bearing melt are approximately 1 log unit below thermodynamic calculations for a similar redox buffering equilibrium involving only solid phases. The measured oxygen fugacities normalized to the fayalite-magnetite-quartz oxygen buffer decrease with temperature from ~-0.8 to ~-1.7 log units at 3 GPa, most likely as a result of increasing dilution of the carbonate liquid with silicate. The normalized fO2 values also decrease with pressure and show a similar decrease with temperature at 6 GPa from ~-1.5 log units at 1,100 °C to ~-2.4 log units at 1,300 °C. In contrast to previous arguments, the stability field of the carbonate-bearing melt extends to lower oxygen fugacity in eclogite rocks than in peridotite rocks, which implies a wider range of conditions over which carbon remains mobile in natural eclogites. The raised prevalence of diamonds in eclogites compared to peridotites may, therefore, reflect more effective scavenging of carbon by melts in these rocks. The ferric iron contents of monomineralic layers of clinopyroxene and garnet contained in the same experiments were also measured using Mössbauer spectroscopy. A preliminary model was derived for determining the fO2 of eclogitic rocks from the compositions of garnet and clinopyroxene, including the Fe3+/ΣFe ratio of garnet, using the equilibrium, The model, which reproduces the independently determined fO2 of the experimental data to within 0.5 log units, can be used to estimate the fO2 of ultrahigh-pressure metamorphic eclogites and cratonic eclogitic xenoliths. Although there

  9. 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.

  10. Magma Ocean Depth and Oxygen Fugacity in the Early Earth--Implications for Biochemistry.

    PubMed

    Righter, Kevin

    2015-09-01

    A large class of elements, referred to as the siderophile (iron-loving) elements, in the Earth's mantle can be explained by an early deep magma ocean on the early Earth in which the mantle equilibrated with metallic liquid (core liquid). This stage would have affected the distribution of some of the classic volatile elements that are also essential ingredients for life and biochemistry - H, C, S, and N. Estimates are made of the H, C, S, and N contents of Earth's early mantle after core formation, considering the effects of variable temperature, pressure, oxygen fugacity, and composition on their partitioning. Assessment is made of whether additional, exogenous, sources are required to explain the observed mantle concentrations, and areas are identified where additional data and experimentation would lead to an improved understanding of this phase of Earth's history.

  11. Measured oxygen fugacities of the Angra dos Reis achondrite as a function of temperature

    USGS Publications Warehouse

    Brett, R.; Stephen, Huebner J.; Sato, M.

    1977-01-01

    Measurements of the oxygen fugacity (f{hook}O2) as a function of temperature (T) were made on an interior bulk sample of the cumulate achondrite, Angra dos Reis. Data clustered between the f{hook}O2-T relationship of the iron-wu??stite assemblage and 1.2 log atm units above iron-wu??stite. Interpretation of the data indicates that, throughout most of the cooling history of the meteorite, f{hook}O2 values were defined by equilibria involving iron-bearing species at values close to the f{hook}O2 of the assemblage iron-wu??stite. Measured f{hook}O2 data are compatible with crystallization and cooling at pressures greater than 50 bars. ?? 1977.

  12. Crystal chemistry of amphiboles: implications for oxygen fugacity and water activity in lithospheric mantle beneath Victoria Land, Antarctica

    NASA Astrophysics Data System (ADS)

    Bonadiman, C.; Nazzareni, S.; Coltorti, M.; Comodi, P.; Giuli, G.; Faccini, B.

    2014-03-01

    Amphibole is the hydrous metasomatic phase in spinel-bearing mantle xenoliths from Baker Rocks, Northern Victoria Land, Antarctica. It occurs in veins or in disseminated form in spinel lherzolites. Both types derive from reaction between metasomatic melts and the pristine paragenesis of the continental lithospheric mantle beneath Northern Victoria Land. To determine the effective role of water circulation during the metasomatic process and amphibole formation, six amphibole samples were fully characterized. Accurate determination of the site population and the state of dehydrogenation in each of these amphiboles was carried out using single-crystal X-ray diffraction, electron microprobe and secondary ion mass spectroscopy on the same single crystal. The Fe3+/ΣFe ratio was determined by X-ray absorption near edge spectroscopy on amphibole powder. The degree of dehydrogenation determined by SIMS is 0.870-0.994 O3(O2-) a.p.f.u., primary and ascribed to the Ti-oxy component of the amphibole, as indicated by atom site populations; post-crystallization H loss is negligible. Estimates of aH2O (0.014-0.054) were determined from the dehydration equilibrium among end-member components assuming that amphiboles are in equilibrium with the anhydrous peridotitic phases. A difference up to 58 % in determination of aH2O can be introduced if the chemical formula of the amphiboles is calculated based on 23 O a.p.f.u. without knowing the effective amount of dehydrogenation. The oxygen fugacity of the Baker Rocks amphibole-bearing mantle xenoliths calculated based upon the dissociation constant of water (by oxy-amphibole equilibrium) is between -2.52 and -1.32 log units below the fayalite-magnetite-quartz (FMQ) buffer. These results are systematically lower and in a narrow range of values relative to those obtained from anhydrous olivine-orthopyroxene-spinel equilibria ( fO2 between -1.98 and -0.30 log units). A comparative evaluation of the two methods suggests that when amphibole

  13. Temperature and Oxygen Fugacity Constraints on CK and R Chondrites and Implications for Water and Oxidation in the Early Solar System

    NASA Technical Reports Server (NTRS)

    Righter, K.; Neff, K. E.

    2007-01-01

    Recent chondritic meteorite finds in Antarctica have included CB, CH, CK and R chondrites, the latter two of which are among the most oxidized materials found in meteorite collections. In this study we present petrographic and mineralogic data for a suite of CK and R chondrites, and compare to previous studies of CK and R, as well as some CV chondrites. In particular we focus on the opaque minerals magnetite, chromite, sulfides, and metal as well as unusual silicates hornblende, biotite, and plagioclase. Several mineral thermometers and oxy-barometers are utilized to calculate temperatures and oxygen fugacities for these unusual meteorites compared to other more common chondrite groups. R and CK chondrites show lower equilibrium temperatures than ordinary chondrites, even though they are at similar petrologic grades (e.g., thermal type 6). Oxygen fugacity calculated for CV and R chondrites ranges from values near the iron-wustite (IW) oxygen buffer to near the fayalite-magnetite-quartz (FMQ) buffer. In comparison, the fO2 recorded by ilmenite-magnetite pairs from CK chondrites are much higher, from FMQ+3.1 to FMQ+5.2. The latter values are the highest recorded for materials in meteorites, and place some constraints on the formation conditions of these magnetite-bearing chondrites. Differences between mineralogic and O isotopic compositions of CK and R chondrites suggest two different oxidation mechanisms, which may be due to high and low water: rock ratios during metamorphism, or to different fluid compositions, or both.

  14. Vanadium Stable Isotope Variations in the Mariana Island Arc: Oxygen Fugacity Versus Magmatic Differentiation

    NASA Astrophysics Data System (ADS)

    Prytulak, J.; Elliott, T.; Halliday, A.; Kelley, K. A.; Nielsen, S. G.; Plank, T.; Schauble, E. A.

    2010-12-01

    A widely held view in igneous geochemistry is that the sub-arc mantle has elevated oxygen fugacity (fO2) compared to the upper mantle source of Mid-Ocean Ridge basalts (MORB). However, debate on the fO2 of the sub-arc mantle has arisen from examination of V/Sc ratios [1], which suggest no difference between the sub-arc mantle and the MORB source. This supposition is contrasted by recent μ-XANES determination of Fe3+/FeΣ in olivine-hosted melt inclusions [2], which supports the more traditional notion of an oxidized source for arc lavas. We have recently developed a method for high precision analyses of stable vanadium (V) isotope variations, able to resolve isotope fractionation to a precision of 0.15‰ 2sd [3, 4]. Theoretical calculations predict that stable V isotope fractionation should be robustly related to changes in fO2, with heavier isotopes favored in oxidizing conditions. Furthermore, V isotopes should be immune to alteration and late-stage degassing processes that could affect fO2 determined by Fe3+/FeΣ ratios. Therefore, examination of this new isotopic tracer in arc lavas may provide insight into the fO2 conditions of their source. Here we present the first stable V isotope measurements (reported as δ51V relative to a standard defined as 0‰) on subduction zone inputs (sediments, MORB) and outputs (arc lavas). We have focused initial efforts on well-characterized lavas from the Mariana central island province [5] and subducting sediment and underlying MORB from ODP Site 801, just outboard of the Mariana trench [6]. We find a surprisingly large, resolvable range in δ51V of the arc lavas of almost 0.8‰, which co-varies with SiO2, CaO, and V/Sc ratios. Co-variation of δ51V with SiO2 and CaO is suggestive of possible influence of clinopyroxene fractionation on the isotope composition. We explore the affects of magmatic differentiation and causes of δ51V inter-suite variability in arc lavas versus the δ51V signature of MORB. [1] Lee, C

  15. Viscosity of carbonate-rich melts under different oxygen fugacity conditions

    NASA Astrophysics Data System (ADS)

    Di Genova, Danilo; Hess, Kai-Uwe; Cimarelli, Corrado; Dingwell, Donald B.

    2015-04-01

    Viscosity is a fundamental property of many materials and its changes affects the fluid dynamics of natural system as well as industrial processes. The mobility of carbonatitic melts, which are carbonate-rich and very fluid melts, has attracted renewed interest in both earth science and industry. In fact, these melts are considered the main transport agent of carbon from the mantle to the crust and may be intimately linked to the generation of kimberlites. At the same time lithium, potassium and sodium carbonate are used as electrolytes in molten carbonate fuel cells which operate at high temperatures (~650° C) for the production of electricity without CO2 emissions. Accurate measurement of the transport property (i.e. viscosity) of carbonatitic melts is a priority in order to understand the carbonatite mobility and reaction rates. Additionally, obtaining accurate viscosity measurements of such low viscosity melts is however an experimental challenge due to volatility, very low torques and chemical melt instability in the viscometer. To overcome these limitations we have customized a Modular Compact Rheometer (MCR 502 from Anton Paar) ad hoc equipped with 2 narrow gap concentric-cylinder geometries of steel and Pt-Au. The rheometer is characterized by an air-bearing-supported synchronous motor with torque ranging between 0.01 μNm and 230 mNm (resolution of 0.1 nNm), achieving very low viscosity measurements in the order of mPa s, temperatures up to 1000° C and shear rates ranging between 1 and 100 sec-1. These experimental conditions well match the temperature-viscosity-shear rate window relevant for carbonate melts. Here we present the calibration of the rheometer and the results of a rheological characterization study on a series of very low viscous synthetic and natural carbonatitic melts at different oxygen fugacity (air and CO2 saturated atmosphere). Viscosity measurements on carbonate melts have been performed in the temperature range between ~650 and 1000

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  17. Using Vanadium in Spinel as a Sensor of Oxygen Fugacity in Meteorites: Applications to Mars, Vesta, and Other Asteroids

    NASA Technical Reports Server (NTRS)

    Righter, K.; Sutton, S.; Danielson, L.; Le, L.; Newville, M.; Pando, K.

    2009-01-01

    Igneous and metamorphic rocks commonly contain a mineral assemblage that allows oxygen fugacity to be calculated or constrained such as FeTi oxides, olivine-opx-spinel, or some other oxybarometer [1]. Some rocks, however, contain a limited mineral assemblage and do not provide constraints on fO2 using mineral equilibria. Good examples of the latter are orthopyroxenites or dunites, such as diogenites, ALH 84001, chassignites, or brachinites. In fact it is no surprise that the fO2 of many of these samples is not well known, other than being "reduced" and below the metal saturation value. In order to bridge this gap in our understanding, we have initiated a study of V in chromites in natural meteorite samples. Because the V pre-edge peak intensity and energy in chromites varies with fO2 (Fig. 1) [2], and this has been calibrated over a large fO 2 range, we can apply this relation to rocks for which we otherwise have no fO2 constraints.

  18. The Fidelity of Olivine-Hosted Melt Inclusions as Recorders of Pre-Eruptive Water Content and Oxygen Fugacity

    NASA Astrophysics Data System (ADS)

    Gaetani, Glenn; O'Leary, Julie; Shimizu, Nobumichi

    2010-05-01

    Olivine-hosted melt inclusions represent an important source of information on both the pre-eruptive H2O contents and oxygen fugacities of basaltic magmas [1]. The principal uncertainty involved with deriving pre-eruptive H2O concentrations from melt inclusions is the potential for diffusive loss or gain of H+ (protons) through the host olivine. Further, it has been proposed that the proton flux associated with H2O loss/gain affects the oxidation state of the inclusion [2,3]. Results from hydration and dehydration experiments carried out on natural inclusion-bearing olivines analyzed by SIMS and XANES confirm that H2O re-equilibratrion occurs rapidly via proton diffusion through the host olivine, and demonstrate that re-equilibration of oxygen fugacity within the inclusion occurs on comparable timescales via diffusion of point defects. Therefore, an olivine-hosted melt inclusion provides a reliable record of both the H2O content and oxygen fugacity of the external melt with which it most recently equilibrated. However, efficient re-equilibration of both H2O and oxygen fugacity limits the utility of olivine-hosted melt inclusions as indicators of mantle processes. Hydration experiments were performed on olivines from Puu Wahi, a scoria cone on the NE rift zone of Mauna Loa volcano. Melt inclusions initially containing 0.36±0.05 wt% H2O were held at 1 GPa and 1250° C in water enriched in 18O (18O/ΣO = 0.977) and D (2H/ΣH = 0.998) to map the transport of protons and oxygen during equilibration of melt inclusions with an external fluid. Dehydration experiments were carried out for 1 to 18 hrs at 1 bar and 1250 ° C on inclusion-bearing olivines in scoria erupted from Cerro Negro volcano, Nicaragua, in 1999. The initial concentration of H2O in these melt inclusions was uniformly high (3.6±0.6 wt%). All run products were analyzed for major elements by electron microprobe and for H2O by SIMS on the Cameca 1280 ion microprobe at WHOI. The oxidation state of Fe was

  19. Fugacity Examples

    ERIC Educational Resources Information Center

    David, Carl W.

    2004-01-01

    Equations related to the computation of fugacity of nonideal gases is presented, with special emphasize on a nontraditional equation of State's fugacity and the van der Waals fugacity. It is seen that both the equations include long-range attractive forces and short-range repulsive forces and thus have similar behaviour.

  20. The Oxidation State of Fe in MORB Glasses and the Oxygen Fugacity of the Upper Mantle

    SciTech Connect

    E Cottrell; K Kelley

    2011-12-31

    Micro-analytical determination of Fe{sup 3+}/{Sigma}Fe ratios in mid-ocean ridge basalt (MORB) glasses using micro X-ray absorption near edge structure ({mu}-XANES) spectroscopy reveals a substantially more oxidized upper mantle than determined by previous studies. Here, we show that global MORBs yield average Fe{sup 3+}/{Sigma}Fe ratios of 0.16 {+-} 0.01 (n = 103), which trace back to primary MORB melts equilibrated at the conditions of the quartz-fayalite-magnetite (QFM) buffer. Our results necessitate an upward revision of the Fe{sup 3+}/{Sigma}Fe ratios of MORBs, mantle oxygen fugacity, and the ferric iron content of the mantle relative to previous wet chemical determinations. We show that only 0.01 (absolute, or < 10%) of the difference between Fe{sup 3+}/{Sigma}Fe ratios determined by micro-colorimety and XANES can be attributed to the Moessbauer-based XANES calibration. The difference must instead derive from a bias between micro-colorimetry performed on experimental vs. natural basalts. Co-variations of Fe{sup 3+}/{Sigma}Fe ratios in global MORB with indices of low-pressure fractional crystallization are consistent with Fe{sup 3+} behaving incompatibly in shallow MORB magma chambers. MORB Fe{sup 3+}/{Sigma}Fe ratios do not, however, vary with indices of the extent of mantle melting (e.g., Na{sub 2}O(8)) or water concentration. We offer two hypotheses to explain these observations: The bulk partition coefficient of Fe{sup 3+} may be higher during peridotite melting than previously thought, and may vary with temperature, or redox exchange between sulfide and sulfate species could buffer mantle melting at {approx} QFM. Both explanations, in combination with the measured MORB Fe{sup 3+}/{Sigma}Fe ratios, point to a fertile MORB source with greater than 0.3 wt.% Fe{sub 2}O{sub 3}.

  1. The effect of water activity and oxygen fugacity on the phase relations and oxidation state of Fe in parental ferrobasaltic magma of Skaergaard

    NASA Astrophysics Data System (ADS)

    Botcharnikov, R.; Koepke, J.; Holtz, F.; McCammon, C.

    2003-04-01

    the water-bearing melt with decreasing oxygen fugacity is more pronounced than that calculated for dry melts after [4]. [1] Toplis MJ &Carroll MR, J. Petrol., 36, 1137-1170, 1995. [2] Lattard D &Partsch GM, Eur. J. Mineral., 13, 467-478, 2001. [3] Berndt J et al., Am. Mineral., 87, 1717-1726, 2002. [4] Kress VC &Carmichael ISE, Contr.Min.Petrol., 108, 82-92, 1991.

  2. Links between oxygen fugacity, slab fluids, and calc-alkaline differentiation of arc magmas (Invited)

    NASA Astrophysics Data System (ADS)

    Kelley, K. A.; Cottrell, E.; Brounce, M. N.

    2013-12-01

    Calc-alkaline differentiation, a process by which magmas become depleted in Fe early in their crystallization history, is observed in magmas at subduction zone settings and is thought to drive arc magmas towards the bulk composition of continental crust. Basaltic arc magmas may achieve calc-alkaline affinity through some combination of high magmatic H2O, which delays the crystallization of silicates (most notably plagioclase), and high magmatic oxygen fugacity (fO2), which enhances the onset of magnetite crystallization. The relative importance of H2O, fO2, and magmatic bulk composition in generating calc-alkaline magma series, however, is not yet clearly resolved. Here, we present new measurements of the oxidation state of Fe (expressed as Fe3+/∑Fe ratio; a proxy for magmatic fO2), in combination with previously-published analyses, of mafic (Mg#≥0.5) olivine-hosted melt inclusions from global arc volcanoes (Galunggung, Paricutin, Cerro Negro, and several volcnaoes from the Mariana and Aleutian arcs), acquired using X-ray Absorption Near Edge Structure spectroscopy. We use the Tholeiitic Index (THI) of Zimmer et al., 2010 to quantify the calc-alkaline affinity of arc magma series (<1 is more calc-alkaline, >1 is more tholeiitic). These volcanoes span a range of calc-alkaline affinity, with THI ranging from 0.65 to 1.3. The Fe3+/∑Fe ratios of arc basalts, corrected for fractional crystallization to 6 wt.% MgO (i.e., Fe3+/∑Fe6.0) range globally from 0.15-0.31 and all but Galunggung are more oxidized than the more tholeiitic basaltic glasses from the Mariana trough back-arc basin (THI=1.4; Fe3+/∑Fe6.0=0.185) or normal MORB (THI=1.6; Fe3+/∑Fe6.0=0.167×0.01). Our results show a strong correlation between THI and Fe3+/∑Fe6.0 ratios at these volcanoes, such that more calc-alkaline magmas contain a greater proportion of oxidized Fe. At the same time, the maximum dissolved H2O contents of basaltic melt inclusions from these volcanoes also strongly correlate

  3. Partition coefficients for iron between plagioclase and basalt as a function of oxygen fugacity - Implications for Archean and lunar anorthosites

    NASA Technical Reports Server (NTRS)

    Phinney, W. C.

    1992-01-01

    As a prelude to determinations of the content of total iron as FeO(T) in melts in equilibrium with calcic anorthosites, the partition coefficients (Ds) for FeO(T) between calcic plagioclase and basaltic melt were determined, as a function of oxygen fugacity (f(O2)), for a basaltic composition that occurs as matrices for plagioclase megacrysts. Results showed that, at the liquidus conditions, the value of D for FeO(T) between calcic plagioclase and tholeiitic basalt changed little (from 0.030 to 0.044) between the very low f(O2) of the iron-wustite buffer and that of the quartz-fayalite-magnetite (QFM) buffer. At fugacities above QFM, the value for D increased rapidly to 0.14 at the magnetite-hematite buffer and to 0.33 in air. The increase in D results from the fact that, at f(O2) below QFM, nearly all of the Fe is in the Fe(2+) state; above QFM, the Fe(3+)/Fe(2+) ratio in the melt increases rapidly, causing more Fe to enter the plagioclase which accepts Fe(3+) more readily than Fe(2+).

  4. Diffusive Re-equilibration of Volatiles and Oxygen Fugacity in Olivine-Hosted Melt Inclusions: Experiments and Numerical Models

    NASA Astrophysics Data System (ADS)

    Bucholz, C. E.; Gaetani, G. A.; Behn, M. D.

    2011-12-01

    Determining the pre-eruptive volatile contents of magmas is of critical importance to understanding their generation and evolution. Mineral-hosted melt inclusions can provide information on the pre-eruptive H2O content of the magma as the host mineral shields the interior melt inclusion from decompression that the exterior magma undergoes as it ascends through the crust [1]. Consequently, melt inclusions have been widely used to provide pre-eruptive water contents (eg. [2]). Yet, there is strong evidence of rapid changes to H2O via proton diffusion through the olivine host crystal [3] that are not limited by redox reactions within the melt inclusion [4]. To quantify the extent to which H2O and other volatiles are faithfully recorded in olivine-hosted melt inclusions, we have combined experiments with numerical models to investigate the processes controlling diffusive re-equilibration of water and oxygen fugacity in an olivine-hosted melt inclusion. Dehydration experiments were performed on olivines from the 1999 Cerro Negro Volcano (Nicaragua) eruption. Melt inclusions with initially high water contents (~3.6 ± 0.6 wt. % H2O) were held at 1 atm and 1100°C at the Ni-NiO buffer for 4 to 72 hours. All run products were analyzed by SIMS on the Cameca 1280 ion microprobe at WHOI for H2O, CO2, SO2, F, and Cl. Using COMSOL Multiphysics finite-element modeling software we modeled the diffusive re-equilibration of water, oxygen fugacity, and other volatiles. To interpret our experimental results we used the geometry of the olivines and melt inclusions from the experiments in the numerical models. Our work confirms that the mechanism for loss or gain of H2O from an olivine-hosted melt inclusion is lattice diffusion of protons. Results from XANES analyses on previous dehydration experiments at 1250 °C indicate that H loss occurs through a process decoupled from fO2 re-equilibration. Re-equilibration of fO2 occurs independently via diffusion of point defects on timescales

  5. An Experimental Study of Eu/Gd Partitioning Between a Shergottite Melt and Pigeonite: Implications for the Oxygen Fugacity of the Martian Interior

    NASA Technical Reports Server (NTRS)

    McCanta, M. C.; Rutherford, M. J.; Jones, J. H.

    2002-01-01

    We experimentally investigated the partitioning behavior of Eu/Gd between a synthetic shergottite melt and pigeonite as a function of oxygen fugacity. This has implications for the oxidation state of the source region of the martian meteorites. Additional information is contained in the original extended abstract.

  6. Intrinsic oxygen fugacity measurements on seven chondrites, a pallasite, and a tektite and the redox state of meteorite parent bodies

    USGS Publications Warehouse

    Brett, R.; Sato, M.

    1984-01-01

    Intrinsic oxygen-fugacity (fO2) measurements were made on five ordinary chondrites, a carbonaceous chondrite, an enstatite chondrite, a pallasite, and a tektite. Results are of the form of linear log fO2 - 1 T plots. Except for the enstatite chondrite, measured results agree well with calculated estimates by others. The tektite produced fO2 values well below the range measured for terrestrial and lunar rocks. The lowpressure atmospheric regime that is reported to follow large terrestrial explosions, coupled with a very high temperature, could produce glass with fO2 in the range measured. The meteorite Salta (pallasite) has low fO2 and lies close to Hvittis (E6). Unlike the other samples, results for Salta do not parallel the iron-wu??stite buffer, but are close to the fayalite-quartz-iron buffer in slope. Minor reduction by graphite appears to have taken place during metamorphism of ordinary chondrites. fO2 values of unequilibrated chondrites show large scatter during early heating suggesting that the constituent phases were exposed to a range of fO2 conditions. The samples equilibrated with respect to fO2 in relatively short time on heating. Equilibration with respect to fO2 in ordinary chondrites takes place between grades 3 and 4 of metamorphism. Application of P - T - fO2 relations in the system C-CO-CO2 indicates that the ordinary chondrites were metamorphosed at pressures of 3-20 bars, as it appears that they lay on the graphite surface. A steep positive thermal gradient in a meteorite parent body lying at the graphite surface will produce thin reduced exterior, an oxidized near-surface layer, and an interior that is increasingly reduced with depth; a shallow thermal gradient will produce the reverse. A body heated by accretion on the outside will have a reduced exterior and oxidized interior. Meteorites from the same parent body clearly are not required to have similar redox states. ?? 1984.

  7. The effect of oxygen fugacity on the partitioning of nickel and cobalt between olivine, silicate melt, and metal

    NASA Technical Reports Server (NTRS)

    Ehlers, Karin; Grove, Timothy L.; Sisson, Thomas W.; Recca, Steven I.; Zervas, Deborah A.

    1992-01-01

    The effect of oxygen fugacity, f(O2), on the partitioning behavior of Ni and Co between olivine, silicate melt, and metal was investigated in the CaO-MgO-Al2O3-SiO2-FeO-Na2O system, an analogue of a chondrule composition from an ordinary chondrite. The conditions were 1350 C and 1 atm, with values of f(O2) varying between 10 exp -5.5 and 10 exp -12.6 atm (i.e., the f(O2) range relevant for crystal/liquid processes in terrestrial planets and meteorite parent bodies). Results of chemical analysis showed that the values of the Ni and Co partitioning coefficients begin to decrease at values of f(O2) that are about 3.9 log units below the nickel-nickel oxide and cobalt-cobalt oxide buffers, respectively, near the metal saturation for the chondrule analogue composition.

  8. Ultra-oxidized redox conditions in subduction mélanges? Decoupling between oxygen fugacity and oxygen availability in a metasomatic environment

    NASA Astrophysics Data System (ADS)

    Tumiati, Simone; Poli, Stefano; Godard, Gaston; Martin, Silvana; Malaspina, Nadia

    2014-05-01

    The manganese ore of Praborna (Italian Western Alps) is embedded within a metasedimentary sequence belonging to a subduction mélange equilibrated at high-pressure conditions (~2 GPa) during the Alpine orogenesis and record environmental conditions typical for a subducting slab setting. The pervasive veining of the ore and the growth of "pegmatoid" HP minerals suggest an open system with large fluid/rock ratio and a strong interaction with slab-derived fluids. This natural case provides an excellent natural laboratory for the study of the oxygen mobility in subducting oceanic slab mélanges at high-P, fluid-present conditions. The Mn-rich rocks in contact with the underlying sulphide- and magnetite-bearing metabasites, in textural and chemical equilibrium with the veins, contain braunite (Mn2+Mn3+6SiO12) + quartz + pyroxmangite (Mn2+SiO3), and minor hematite, omphacite, the epidote piemontite and spessartine-rich garnet. Similarly to Fe-bearing systems, Mn oxides and silicates can be regarded as natural redox-sensors, capable to monitor a process of fluid infiltration that could fix externally the intensive variable fO2 (or μO2). Sulphides are absent in these Mn-rich rocks, sulphates (barite, celestine) occurring instead together with As- and Sb oxides and silicates. On the basis of the observed assemblages, new thermodynamic calculations show that these mélange rocks are characterized by unrealistic ultra-oxidized states (ΔFMQ up to +12) if the chemical potential of oxygen (or the oxygen fugacity) is accounted for. However, if the molar quantity of oxygen in excess with reference to with reference to a system where all iron and manganese are considered to be ferrous, the ore appears only moderately oxidized, and comparable to typical subduction-slab mafic eclogites. Therefore, oxygen can be hardly considered a perfectly mobile component, even in the most favourable conditions. In the Earth's interior redox reactions take place mainly among solid oxides and

  9. Ultra-oxidized rocks in subduction mélanges? Decoupling between oxygen fugacity and oxygen availability in a Mn-rich metasomatic environment

    NASA Astrophysics Data System (ADS)

    Tumiati, Simone; Godard, Gaston; Martin, Silvana; Malaspina, Nadia; Poli, Stefano

    2015-06-01

    The manganese ore of Praborna (Italian Western Alps) is embedded within a metasedimentary sequence belonging to a subduction mélange equilibrated at high-pressure (HP) conditions (ca. 2 GPa) during the Alpine orogenesis. The pervasive veining of the ore and the growth of "pegmatoid" HP minerals suggest that these Mn-rich rocks strongly interacted with slab-derived fluids during HP metamorphism. These rocks are in textural and chemical equilibrium with the veins and in contact with sulphide- and magnetite-bearing metabasites at the bottom of the sequence. They contain braunite (Mn2+Mn3+6SiO12), quartz, pyroxmangite (Mn2+SiO3), and minor hematite, omphacite, piemontite and spessartine-rich garnet. Sulphides are absent in the Mn-rich rocks, whereas sulphates (barite, celestine) occur together with As- and Sb-oxides and silicates. This rock association provides an excellent natural laboratory to constrain the redox conditions in subducting oceanic slab mélanges at HP and fluid-present conditions. Similarly to Fe-bearing minerals, Mn oxides and silicates can be regarded as natural redox-sensors. A thermodynamic dataset for these Mn-bearing minerals is built, using literature data as well as new thermal expansion parameters for braunite aud pyrolusite, derived from experiments. Based on this dataset and the observed assemblages at Praborna, thermodynamic calculations show that these mélange rocks are characterised by ultra-oxidized conditions (∆FMQ up to + 12.7) if the chemical potential of oxygen (or the oxygen fugacity fO2) is accounted for. On the other hand, if the molar quantity of oxygen is used as the independent state variable to quantify the bulk oxidation state, the ore appears only moderately oxidized and comparable to typical subduction-slab mafic eclogites. Such an apparent contradiction may happen in rock systems whenever oxygen is improperly considered as a perfectly mobile component. In the Earth's mantle, redox reactions take place mainly between

  10. Determining the Oxygen Fugacity of Lunar Pyroclastic Glasses Using Vanadium Valence - An Update

    NASA Technical Reports Server (NTRS)

    Karner, J. M.; Sutton, S. R.; Papike, J. J.; Shearer, C. K.; Jones, J. H.; Newville, M.

    2004-01-01

    We have been developing an oxygen barometer based on the valence state of V (V(2+), V(3+), V(4+), and V(5+)) in solar system basaltic glasses. The V valence is determined by synchrotron micro x-ray absorption near edge structure (XANES), which uses x-ray absorption associated with core-electronic transitions (absorption edges) to reveal a pre-edge peak whose intensity is directly proportional to the valence state of an element. XANES has advantages over other techniques that determine elemental valence because measurements can be made non-destructively in air and in situ on conventional thin sections at a micrometer spatial resolution with elemental sensitivities of approx. 100 ppm. Recent results show that fO2 values derived from the V valence technique are consistent with fO2 estimates determined by other techniques for materials that crystallized above the IW buffer. The fO2's determined by V valence (IW-3.8 to IW-2) for the lunar pyroclastic glasses, however, are on the order of 1 to 2.8 log units below previous estimates. Furthermore, the calculated fO2's decrease with increasing TiO2 contents from the A17 VLT to the A17 Orange glasses. In order to investigate these results further, we have synthesized lunar green and orange glasses and examined them by XANES.

  11. Genesis of high-Mg andesites through shallow fractionation of primitive arc basalts at elevated oxygen fugacities

    NASA Astrophysics Data System (ADS)

    Zellmer, G. F.; Shellnutt, J. G.

    2009-12-01

    The petrogenesis of high-Mg andesites has been linked to a variety of processes, including partial melting of hydrous mantle peridotite, re-equilibration of partial melts of the subducting slab with the mantle wedge, and assimilation of lower crustal cumulates into dacitic melts. Yet none of these processes can explain the recently identified association of adakitic andesites, many of which are high-Mg andesites, with regions of elevated surface heat flux that are likely related to unusually shallow magma ponding levels in the upper crust (Zellmer, 2009). Using MELTS modeling, we demonstrate here that at high oxygen fugacities (NNO+2, which based on whole-rock Fe3+/Fe2+ ratios is appropriate for the Western and Central Aleutians, the Trans-Mexican Volcanic Belt, and the Setouchi Volcanic Belt), shallow crustal pressures (0.7 kbar), and initial H2O contents between 0.5 and 4 wt%, iron-magnesium spinel will be fractionated from primitive arc basalts, producing andesitic residual melts with elevated Mg#. Subsequent assimilation of a few percent of autocrystic mafic phases makes typical high-Mg andesites with forsteritic olivines. Orthopyroxenes in equilibrium with these melts are Cr-rich due to increased uptake of Cr into orthopyroxene (Dopx/lq≥25) at lower temperatures (≤1130°C) and elevated oxygen fugacities (NNO+2). While arc magmas with high initial H2O contents will undergo early degassing induced crystallization and viscous stagnation, lower primary melt H2O contents will result in delayed crystallization and shallower magma ponding levels, accounting for elevated surface heat flux. Our findings are therefore consistent with the location of many high-Mg andesites in areas of high surface heat flux, and challenge the commonly accepted notion that these compositions are particularly hydrous primary melts generated in equilibrium with mantle peridotite. Reference: Zellmer G.F. (2009) Petrogenesis of Sr-rich adakitic rocks at volcanic arcs: insights from global

  12. Oxygen fugacity determined from iron oxidation state in natural (Mg,Fe)O ferropericlase: new insights for lower mantle diamond formation

    NASA Astrophysics Data System (ADS)

    Longo, M.; McCammon, C.; Bulanova, G.; Kaminsky, F. V.; Tappert, R.

    2009-12-01

    The most common mineral found in diamonds originating in the lower mantle is (Mg,Fe)O ferropericlase (more than 50 percent of occurrences). Since it is well known that the Fe3+ concentration in (Mg,Fe)O is sensitive to oxygen fugacity, even at high pressures, the determination of Fe3+ over Fe total in such inclusions provides a direct method for investigating lower mantle redox conditions during diamond formation. Therefore, the goal of this study is to measure Fe3+ using a new method, namely the flank method (EMPA) in (Mg,Fe)O lower mantle diamond inclusions from a wide range of sites worldwide in order to explore the variation of oxygen fugacity with chemical, physical and geographic parameters. Eighteen (Mg,Fe)O ferropericlase inclusions from ultra deep diamonds selected worldwide (four from Juina area, Brazil, two from Machado River, Brazil, and twelve from Ororoo, Australia) were analyzed by the flank method. Inclusions were all less than 50 microns in size. Our results follow the theoretical trend described by the synthetic samples, confirming high phase homogeneity for most of the samples. Flank method measurements show a large range of redox conditions for (Mg,Fe)O inclusions, with a Fe3+ over Fe total ratio varying between 1 and 15 percent, similar to results for a suite of much larger diameter inclusions that were studied using Mössbauer spectroscopy. Inclusions recovered from the same host diamond show a strong redox gradient, which leads to the conclusion of varying oxygen fugacity conditions involved in the formation of the inclusions. These observations combined with the geographical correlation observed among all inclusions measured in the present work and from previous studies in literature leads to the suggestion of other mechanisms than subducted slabs being involved in diamond formation. In order to provide insights on the mechanisms controlling the redox conditions at lower mantle depths and how a heterogeneous oxygen fugacity may affect the

  13. Roles of magmatic oxygen fugacity and water content in generating signatures of continental crust in the Alaska-Aleutian arc

    NASA Astrophysics Data System (ADS)

    Kelley, K. A.; Cottrell, E.; Brounce, M. N.; Gentes, Z.

    2014-12-01

    Early depletion of Fe during magmatic differentiation is a characteristic of many arc magmas, and this may drive them towards the bulk composition of continental crust. In the Alaska-Aleutian arc, magmas are strongly Fe-depleted both in the east, where the arc sits atop pre-existing continental crust, and in the west, where the system is oceanic but convergence is highly oblique. Primary basaltic arc magmas may achieve early Fe depletion through a combination of high magmatic H2O, which delays silicate saturation, and high oxygen fugacity (fO2), which promotes early onset of Fe-oxide crystallization. Alternatively, low-Fe, high Mg# magmas may emerge directly from the arc mantle, possibly due to slab melting, driving mixing with Fe-rich basaltic magmas. Yet, the relative importance of H2O, fO2, and magmatic bulk composition in generating Fe-depletion is not clearly resolved. Here, we present new measurements of the oxidation state of Fe (Fe3+/∑Fe ratio; a proxy for magmatic fO2), in combination with major element and volatile data, of olivine-hosted melt inclusions from four Alaska-Aleutian arc volcanoes (Okmok, Seguam, Korovin, Augustine), acquired using XANES spectroscopy. We use the Tholeiitic Index (THI) of Zimmer et al., 2010 to quantify the behavior of Fe in each volcano magma series (<1 is Fe-depleted, >1 is Fe-enriched). These volcanoes span a range of THI, from 0.9-0.65. The Fe3+/∑Fe ratios of Aleutian basalts, corrected for fractional crystallization to 6 wt.% MgO (i.e., Fe3+/∑Fe6.0) range from 0.22-0.31 and correlate strongly with THI (r2>0.99), such that more Fe-depleted magmas contain a greater proportion of oxidized Fe. The maximum dissolved H2O contents of basaltic melt inclusions from these volcanoes also strongly correlate with THI (r2>0.96), and with measured Fe3+/∑Fe ratios (although H2O is not the direct cause of oxidation). These links point to a slab-derived origin of both H2O and oxidation and thus relate slab fluxes to the Fe

  14. A Mössbauer and X-ray diffraction study of annites synthesized at different oxygen fugacities and crystal chemical implications

    NASA Astrophysics Data System (ADS)

    Redhammer, G. J.; Beran, A.; Dachs, E.; Amthauer, G.

    1993-12-01

    A refined set of Mössbauer parameters (isomer shifts, quadrupole splittings, Fe2+/Fe3+ ratios) and lattice parameters were obtained from annites synthesized hydrothermally at pressures between 3 and 5 kbars, temperatures ranging from 250 to 780° C and oxygen fugacities controlled by solid state buffers (NNO, QMF, IM, IQF). Mössbauer spectra showed Fe2+ and Fe3+ on both the M1 and the M2 site. A linear relationship between Fe3+ content and oxygen fugacity was observed. Towards low Fe3+ values this linear relationship ends at ≈10% of total iron showing that the Fe3+ content cannot be reduced further even if more reducing conditions are used. This indicates that in annite at least 10% Fe2+ are substituted by Fe3+ in order to match the larger octahedral layer to the smaller tetrahedral layer. IR spectra indicate that formation of octahedral vacancies plays an important role for charge balance through the substitution 3 Fe2+ → 2 Fe3+ + ▪(oct).

  15. Oxygen fugacities determined from iron oxidation state in natural (Mg,Fe)O ferropericlase: new insights into lower mantle diamond formation

    NASA Astrophysics Data System (ADS)

    Longo, Micaela; McCammon, Catherine; Bulanova, Galina; Kaminsky, Felix; Tappert, Ralf

    2010-05-01

    Mineral inclusions in diamonds reflect the chemical composition and mineral assemblages of the two principal rock types occurring in the deep lithosphere, peridotite and eclogite. However, in the past two decades, the discovery of rare diamonds containing inclusions such as former Mg,Si-perovskite and (Mg,Fe)O ferropericlase led to the possibility that diamonds can form also at greater depths. (Mg,Fe)O ferropericlase is the most commonly found inclusion in lower mantle diamonds (more than 50% of the occurrences). Since the Fe3+ concentration in (Mg,Fe)O is sensitive to oxygen fugacity also at high pressures (Frost et al., 2004), the determination of Fe3+/Σ Fe in such inclusions provides a direct method for investigating lower mantle redox conditions during diamond formation. In the present study we explore whether variations in mantle oxygen fugacity exist as a function of chemical, physical and geographic parameters, by studying (Mg,Fe)O inclusions in lower mantle diamonds from a wide range of localities. Eighteen (Mg,Fe)O ferropericlase inclusions from lower mantle diamonds selected worldwide were measured by the flank method using the calibration previously established for synthetic ferropericlase (Longo et al., in preparation). The Fe3+/Σ Fe measured in (Mg,Fe)O inclusions of the present work (Juina, Brazil, Machado River, Brazil and Orroroo, Australia) were compared to data already available for other inclusions of larger size previously measured by Mössbauer spectroscopy (McCammon et al. 1997, 2004). Oxygen fugacity was estimated for each specimen relative to two reference buffers such as the Fe-(Mg,Fe)O buffer (reducing conditions) and the Re-ReO2 buffer (oxidizing conditions). Our results show a dependence on geographical location, and in particular, inclusions from the African province (Kankan Guinea) seem to record more reducing mantle conditions than the inclusions measured from the other provinces, which cover a larger range of fO2 conditions. It is

  16. Magnetite activities across the MgAl2O4-Fe3O4 spinel join, with application to thermobarometric estimates of upper mantle oxygen fugacity

    NASA Astrophysics Data System (ADS)

    Mattioli, Glen S.; Wood, Bernard J.

    1988-02-01

    The activity of Fe3O4 component in MgAl2O4-Fe3O4 spinels has been measured at 900° and 1000° C and 1 atm total pressure using a zirconia oxygen electrolyte. As previously reported for the dilute Fe3O4 concentration region (Mattioli and Wood 1986a), magnetite activity at 1000° C is greater than at 900° C at constant Fe3O4 mole fraction, for compositions across the MgAl2O4-Fe3O4 join between 20 and 80 mol% Fe3O4 component. The 1-atm solvus crest lies between 900° and 1000° C and, at 900° C the limbs are at Fe3O4 mole fractions of 0.2 and 0.6 approximately. Application of the O'Neill and Navrotsky (1983, 1984) cation distribution model indicates that the unusual activity — composition behavior of Fe3O4 is caused by changes in the equilibrium state of disorder of mixed MgAl2O4-Fe3O4 spinels relative to the disordered Fe3O4 standard state. In addition, both stoichiometric volumes (Mattioli et al. 1987) and activities across the MgAl2O4-Fe3O4 join suggest that short range order is significant for this binary. Excess free energy terms must be added to “ideal” Fe3O4 activities formulated from equilibrium cation distributions in complex MgAl2O4-Fe3O4 spinels in order to increase Fe3O4 activities to values consistent with observation and to generate the apparent region of immiscibility at 900° C. We have applied our activity data to the estimation of upper mantle spinel-lherzolite oxygen fugacities. We calculated that minimum f_{O_2 }'s are about 2 log units below the synthetic QFM buffer at 15 kbar total pressure for Fe3O4 concentration of 2 mol%, in a Cr-free spinel phase. If a preliminary calibration of an additional 25 mol% Fe2+-substitution as FeCr2O4 or FeAl2O4 component is incorporated into Fe3O4 activity, then olivine-orthopyroxene-spinel assemblages of depleted-Type 1-spinel-lherzolite xenoliths indicate f_{O_2 }'s close to QFM at 15 kbar. This is in good agreement with previous thermobarometric f_{O_2 } estimates and in sharp contrast to 1 atm

  17. Decoupling of H2O, Oxygen Fugacity and Incompatible Elements in Olivine-Hosted Melt Inclusions By Diffusive Re-Equilibration (Invited)

    NASA Astrophysics Data System (ADS)

    Gaetani, G. A.; O'Leary, J. A.; Shimizu, N.; Bucholz, C. E.

    2010-12-01

    Mineral-hosted melt inclusions provide information on the pre-eruptive H2O contents of degassed magmas. The strength of the host mineral protects included silicate melts from the decompression experienced by the entraining magma. This allows melt inclusions to retain their pre-eruptive volatiles and, thereby, provides a source of information on the amount of H2O in magmatic systems. Recent studies have used this to investigate (1) relationships between H2O and oxygen fugacity [1] and (2) the influence of H2O on extent of peridotite partial melting beneath back arc spreading centers [2,3]. We combined experiments and numerical models to investigate the potential for decoupling of these variables through diffusive re-equilibration during episodes of degassing or magma mixing. Our results demonstrate that re-equilibration of H2O and oxygen fugacity occur on short timescales and are independent of one another. Therefore, relationships between H2O and oxygen fugacity are likely to be robust, reflecting pre-eruptive condition. For incompatible elements, such as TiO2, slow diffusivity and low concentration in olivine results in inefficient diffusive re-equilibration. Therefore, relationships between H2O and incompatible elements, such as TiO2, can be significantly perturbed by loss or gain of protons through the host olivine. Hydration experiments were performed on olivines from the NE rift zone of Mauna Loa volcano. Melt inclusions initially containing 0.36±0.05 wt% H2O were held at 1 GPa and 1250°C in water enriched in 18O (18O/∑O = 0.977) and D (2H/∑H = 0.998) to map the transport of protons and oxygen during equilibration of melt inclusions with an external fluid. Dehydration experiments were carried out for 1 to 18 hrs at 1 bar and 1250°C on inclusion-bearing olivines in scoria erupted from Cerro Negro volcano, Nicaragua. Initial concentrations of H2O in these melt inclusions are uniformly high (3.6±0.6 wt%). All run products were analyzed by SIMS on the

  18. The W-W02 Oxygen Fugacity Buffer at High Pressures and Temperatures: Implications for f02 Buffering and Metal-silicate Partitioning

    NASA Technical Reports Server (NTRS)

    Shofner, G. A.; Campbell, A. J.; Danielson, L.; Righter, K.

    2013-01-01

    Oxygen fugacity (fO2) controls multivalent phase equilibria and partitioning of redox-sensitive elements, and it is important to understand this thermodynamic parameter in experimental and natural systems. The coexistence of a metal and its oxide at equilibrium constitutes an oxygen buffer which can be used to control or calculate fO2 in high pressure experiments. Application of 1-bar buffers to high pressure conditions can lead to inaccuracies in fO2 calculations because of unconstrained pressure dependencies. Extending fO2 buffers to pressures and temperatures corresponding to the Earth's deep interior requires precise determinations of the difference in volume (Delta) V) between the buffer phases. Synchrotron x-ray diffraction data were obtained using diamond anvil cells (DAC) and a multi anvil press (MAP) to measure unit cell volumes of W and WO2 at pressures and temperatures up to 70 GPa and 2300 K. These data were fitted to Birch-Murnaghan 3rd-order thermal equations of state using a thermal pressure approach; parameters for W are KT = 306 GPa, KT' = 4.06, and aKT = 0.00417 GPa K-1. Two structural phase transitions were observed for WO2 at 4 and 32 GPa with structures in P21/c, Pnma and C2/c space groups. Equations of state were fitted for these phases over their respective pressure ranges yielding the parameters KT = 190, 213, 300 GPa, KT' = 4.24, 5.17, 4 (fixed), and aKT = 0.00506, 0.00419, 0.00467 GPa K-1 for the P21/c, Pnma and C2/c phases, respectively. The W-WO2 buffer (WWO) was extended to high pressure by inverting the W and WO2 equations of state to obtain phase volumes at discrete pressures (1-bar to 100 GPa, 1 GPa increments) along isotherms (300 to 3000K, 100 K increments). The slope of the absolute fO2 of the WWO buffer is positive with increasing temperature up to approximately 70 GPa and is negative above this pressure. The slope is positive along isotherms from 1000 to 3000K with increasing pressure up to at least 100 GPa. The WWO buffer is at

  19. Computer program for calculation of oxygen uptake

    NASA Technical Reports Server (NTRS)

    Castle, B. L.; Castle, G.; Greenleaf, J. E.

    1979-01-01

    A description and operational precedures are presented for a computer program, written in Super Basic, that calculates oxygen uptake, carbon dioxide production, and related ventilation parameters. Program features include: (1) the option of entering slope and intercept values of calibration curves for the O2 and CO2 and analyzers; (2) calculation of expired water vapor pressure; and (3) the option of entering inspured O2 and CO2 concentrations. The program is easily adaptable for programmable laboratory calculators.

  20. The Mineralogical Record of Oxygen Fugacity Variation and Alteration in Northwest Africa 8159: Evidence for Interaction Between a Mantle Derived Martian Basalt and a Crustal Component(s)

    NASA Technical Reports Server (NTRS)

    Shearer, Charles K.; Burger, Paul V.; Bell, Aaron S.; McCubbin, Francis M.; Agee, Carl; Simon, Justin I.; Papike, James J.

    2015-01-01

    A prominent geochemical feature of basaltic magmatism on Mars is the large range in initial Sr isotopic ratios (approx. 0.702 - 0.724) and initial epsilon-Nd values (approx. -10 to greater than +50). Within this range, the shergottites fall into three discreet subgroups. These subgroups have distinct bulk rock REE patterns, mineral chemistries (i.e. phosphate REE patterns, Ni, Co, V in olivine), oxygen fugacity of crystallization, and stable isotopes, such as O. In contrast, nakhlites and chassignites have depleted epsilon-Nd values (greater than or equal to +15), have REE patterns that are light REE enriched, and appear to have crystallized near the FMQ buffer. The characteristics of these various martian basalts have been linked to different reservoirs in the martian crust and mantle, and their interactions during the petrogenesis of these magmas. These observations pose interesting interpretive challenges to our understanding of the conditions of the martian mantle (e.g. oxygen fugacity) and the interaction of mantle derived magmas with the martian crust and surface. Martian meteorite NWA 8159 is a unique fine-grained augite basalt derived from a highly depleted mantle source as reflected in its initial epsilon-Nd value, contains a pronounced light REE depleted pattern, and crystallized presumably under very oxidizing conditions. Although considerably older than both shergottites and nahklites, it has been petrogenetically linked to both styles of martian magmatism. These unique characteristics of NWA 8159 may provide an additional perspective for deciphering the petrogenesis of martian basalts and the nature of the crust of Mars.

  1. Genesis of high-Mg andesites (HMA) through shallow fractionation of primitive arc basalts at elevated oxygen fugacities (and low initial water contents)

    NASA Astrophysics Data System (ADS)

    Zellmer, Georg; Shellnutt, Gregory

    2010-05-01

    The petrogenesis of high-Mg andesites has been linked to a variety of processes, including partial melting of hydrous mantle peridotite, re-equilibration of partial melts of the subducting slab with the mantle wedge, and assimilation of lower crustal cumulates into dacitic melts. Yet none of these processes can explain the recently identified association of adakitic andesites, many of which are high-Mg andesites, with regions of elevated surface heat flux that are related to unusually shallow magma ponding levels in the upper crust (Zellmer, 2009). Using MELTS modeling, we demonstrate here that at elevated oxygen fugacities (NNO+2, which based on whole-rock Fe3+/Fe2+ ratios is appropriate for the Western and Central Aleutians, the Trans-Mexican Volcanic Belt, and the Setouchi Volcanic Belt), shallow crustal pressures (0.7 kbar), and initial H2O contents between 0.5 and 4 wt%, iron-magnesium spinel will be fractionated from primitive arc basalts, producing andesitic residual melts with elevated Mg#. Subsequent assimilation of a few percent of autocrystic mafic phases makes typical high-Mg andesites with forsteritic olivines. Orthopyroxenes in equilibrium with these melts are Cr-rich due to increased uptake of Cr into orthopyroxene (Dopx-lq ≥25) at lower temperatures (≤1130° C) and elevated oxygen fugacities (NNO+2). While arc magmas with high initial H2O contents will undergo early degassing induced crystallization and viscous stagnation, lower primary melt H2O contents will result in delayed crystallization and shallower magma ponding levels, accounting for elevated surface heat flux. Our findings are therefore consistent with the location of many high-Mg andesites in areas of high surface heat flux, and challenge the commonly accepted notion that these compositions are particularly hydrous primary melts generated in equilibrium with mantle peridotite. Reference: Zellmer G.F. (2009) Petrogenesis of Sr-rich adakitic rocks at volcanic arcs: insights from global

  2. Experimental Rate Study of Vitrinite Maturation as a Function of Temperature, Time, Starting Material, Aqueous Fluid Pressure, and Oxygen Fugacity: Corroboration of Prior Work

    NASA Astrophysics Data System (ADS)

    Ernst, W. G.; Mählmann, R. F.

    2002-05-01

    Kinetic studies were performed on disaggregated samples of gymnosperm and angiosperm huminite at 2.0 kbar aqueous fluid pressure and oxygen fugacities defined by hematite-magnetite and magnetite + quartz-fayalite solid buffers. Individual experiments lasted from 5-204 days. The rate of vitrinite reflectance (VR) increase was evaluated at 200, 250, 300, and 400oC isotherms; experimentally determined, approximately steady-state values for the mean percentage Rmax are 0.54, 0.74, 1.10, and 2.25, respectively. The overall activation energy governing the kinetics of several devolatilization reactions responsible for increase in VR measured in our experiments is 21.8+/- 0.3 kJ/mol. Combined with earlier rate studies conducted by Dalla Torre et al. (1997), we conclude that the rate of vitrinite maturation is unaffected by oxidation state, "wet" versus "dry" conditions, and the nature of the starting lignitic material. To a small extent, elevated lithostatic pressure retards the rate of increase in VR. These new run data demonstrate that VR is chiefly a function of temperature and time. In support of most earlier field, theoretical, and laboratory studies, our research indicates that, for all but geologically insignificant times intervals, vitrinite reflectance is an appropriate proxy for host-rock burial temperature.

  3. Oxygen Fugacity of Mare Basalts and the Lunar Mantle Application of a New Microscale Oxybarometer Based on the Valence State of Vanadium

    NASA Technical Reports Server (NTRS)

    Shearer, C. K.; Karner, J.; Papike, J. J.; Sutton, S. R.

    2004-01-01

    The ability to estimate oxygen fugacities for mare basalts and to extend these observations to the lunar mantle is limited using bulk analysis techniques based on buffering assemblages or the valence state of iron. These limitations are due to reequilibration of mineral assemblages at subsolidus conditions, deviations of mineral compositions from thermodynamic ideality, size requirements, and the limits of the iron valence at very low fO2. Still, these approaches have been helpful and indicate that mare basalts crystallized at fO2 between the iron-w stite buffer (IW) and the ilmenite breakdown reaction (ilmenite = rutile + iron). It has also been inferred from these estimates that the lunar mantle is also highly reduced lying at conditions below IW. Generally, these data cannot be used to determine if the mare basalts become increasingly reduced during transport from their mantle source and eruption at the lunar surface and if there are differences in fO2 among mare basalts or mantle sources. One promising approach to determining the fO2 of mare basalts is using the mean valence of vanadium (2+, 3+, 4+, 5+) determined on spots of a few micrometers in diameter using synchrotron x-ray absorption fine structure (XAFS) spectroscopy. The average valence state of V in basaltic glasses is a function of fO2, temperature, V coordination, and melt composition. Here, we report the initial results of this approach applied to lunar pyroclastic glasses.

  4. Synchrotron Micro-XANES Measurements of Vanadium Oxidation State in Glasses as a Function of Oxygen Fugacity: Experimental Calibration of Data Relevant to Partition Coefficient Determination

    NASA Technical Reports Server (NTRS)

    Delaney, J. S.; Sutton, S. R.; Newville, M.; Jones, J. H.; Hanson, B.; Dyar, M. D.; Schreiber, H.

    2000-01-01

    Oxidation state microanalyses for V in glass have been made by calibrating XANES spectral features with optical spectroscopic measurements. The oxidation state change with fugacity of O2 will strongly influence partitioning results.

  5. Comparative Planetary Mineralogy: V/(Cr+Al) Systematics in Chromites as an Indicator of Relative Oxygen Fugacity

    NASA Technical Reports Server (NTRS)

    Papike, J. J.; Kamer, J. M.; Shearer, C. K.

    2004-01-01

    As our contribution to the new "Oxygen in the Solar System" initiative of the Lunar and Planetary Institute and the NASA Cosmochemistry Program, we have been developing oxygen barometers based largely on behavior of V which can occur in four valence states V2+, V3+, V4+, and V5+, and record at least 8 orders of magnitude of fO2. Our first efforts in measuring these valence proportions were by XANES techniques in basaltic glasses from Earth, Moon, and Mars. We now address the behavior of V valence states in chromite in basalts from Earth, Moon, and Mars. We have been looking for a "V in chromite oxybarometer" that works with data collected by the electron microprobe and thus is readily accessible to a large segment of the planetary materials community. This paper describes very early results that will be refined over the next two years.

  6. Lateral variation in oxygen fugacity and halogen contents in early Cretaceous magmas in Jiaodong area, East China: Implication for triggers of the destruction of the North China Craton

    NASA Astrophysics Data System (ADS)

    Huang, Xiao-Long; He, Peng-Li; Wang, Xue; Zhong, Jun-Wei; Xu, Yi-Gang

    2016-04-01

    Pacific subduction has been suggested as the trigger of the destruction of the North China Craton, but evidence for it remains ambiguous. To further investigate this issue, we studied Wulian pyroxene monzonite (123 ± 1 Ma) in the west and Rushan gabbro-diorite (115 ± 1 Ma) in the east of the Sulu orogen, East China. The rocks of both locations are characterized by low TiO2 but high SiO2 and K2O, fractionated REE patterns with notable negative Ta-Nb-Ti anomalies, and by high initial 87Sr/86Sr ratios and strongly negative εNd (t) and εHf (t) values. These geochemical and isotopic characteristics can be interpreted to be formed by partial melting of enriched lithosphere mantle refertilized by recycled crustal materials that were associated with the Sulu orogeny. Oxygen fugacities of the Rushan gabbro-diorites, estimated based on magnetite-ilmenite equilibration, are significantly higher than those of Wulian pyroxene monzonite. This lateral difference is mirrored by lower F and F/Cl but higher Cl in biotite in the Rushan gabbro-diorite compared to Wulian pyroxene monzonite. All these data suggest a spatially heterogeneous Cretaceous mantle source in terms of halogens and water contents beneath the Sulu orogen, which was most likely caused by the subduction processes of the Pacific plate. H2O-rich fluid in the mantle beneath the east of the Sulu orogen closer to the mantle wedge was prominently from early dehydration of subducted slab at shallow depth, while F-bearing fluid to further west was released by dehydrated deeper slab or stagnant oceanic slab within the mantle transition zone.

  7. Local structural variation with oxygen fugacity in Fe2SiO4+x fayalitic iron silicate melts

    NASA Astrophysics Data System (ADS)

    Alderman, O. L. G.; Lazareva, L.; Wilding, M. C.; Benmore, C. J.; Heald, S. M.; Johnson, C. E.; Johnson, J. A.; Hah, H.-Y.; Sendelbach, S.; Tamalonis, A.; Skinner, L. B.; Parise, J. B.; Weber, J. K. R.

    2017-04-01

    The structure of molten Fe2SiO4+x has been studied using both high-energy X-ray diffraction and Fe K-edge X-ray absorption near-edge structure (XANES) spectroscopy, combined with aerodynamic levitation and laser beam heating. A wide range of Fe3+ contents were accessed by varying the levitation and atmospheric gas composition. Diffraction measurements were made in the temperature (T) and oxygen partial pressure ranges 1624(21) < T < 2183(94) K (uncertainties in parentheses) and -5.6(3) < ΔFMQ < +2.8(5) log units (relative to the Fayalite-Magnetite-Quartz buffer). Iron K-edge XANES measurements covered the ranges 1557(33) < T < 1994(36) K and -2.1(3) < ΔFMQ < +4.4(3) log units. Fe3+ contents, x = Fe3+/ΣFe, estimated directly from the pre-edge peaks of the XANES spectra varied between 0.15(1) and 0.40(2). While these agree in some cases with semi-empirical models, notable discrepancies are discussed in the context of the redox kinetics and the limitations in both the models and in the calibrations used to derive oxidation state from XANES spectra. XANES pre-edge peak areas imply average Fe-O coordination numbers, nFeO, close to 5 for all Fe3+/ΣFe. Diffraction measurements yielded values of 4.4(2) < nFeO < 4.7(1). There is limited evidence for a linear trend nFeO(x) = 4.46(3) + 0.4(1)x. Asymmetric Fe-O bond length distributions peak at around 1.96 Å and have a shoulder arising from longer interatomic distances. Mean rFeO lie close to 2.06 Å, consistent with nFeO close to 5. These observations suggest that Fe2+ is less efficient at stabilizing tetrahedral Fe3+ compared to large monovalent alkali cations. Comparison of in-situ XANES estimates of Fe3+/ΣFe in the melts to those of the quenched solids obtained from XANES as well as Mössbauer spectroscopy indicate rapid oxidation during cooling, enabled by stirring of the melt by the levitation gas flow. As such, the oxidation state of hot komatiitic and other highly fluid melts may not be retained, even during

  8. Phase relation of C-Mg-Fe-Si-O system under various oxygen fugacity conditions by in situ X-ray diffraction experiments: Implication for planetary interior

    NASA Astrophysics Data System (ADS)

    Takahashi, S.; Ohtani, E.; Terasaki, H.; Ito, Y.; Funakoshi, K.; Higo, Y.

    2011-12-01

    Carbon is one of the major volatile elements and very important in the Earth, primitive meteorites and some achondrites, such as ureilites. The abundance of carbon has been estimated to be 100 times higher than that in the CI chondrite, in some of the stars with exoplanets, such as the circumstellar gas around Beta Pictoris (Roberge et al., 2006). In such a gas, carbon-enriched planets, "carbon-planet", may be formed. Carbon-planet interior is likely to be composed mainly of Carbon-bearing phase, such as carbide, carbonate, graphite and diamond. Therefore, it is important to investigate phase relations of carbon-rich systems under high pressure conditions. In this study, C-enriched Mg-Si-Fe-O system was investigated at high pressure and temperature in order to understand the internal structure of the carbon-planets. Phase relations were studied based on 2 series of experiments; (I) textural observation and chemical analysis of the sample recovered from high pressure and temperature and (II) in situ X-ray diffraction experiments. We used several different mineral assemblages for the starting materials, as shown below: (i) (Mg1.8,Fe0.2)SiO4 + Fe + SiO2 + C, (ii) (Mg1.8,Fe0.2)SiO4 + Fe + Si + C, (iii) MgO + Fe + SiO2 + C, (iv) MgO + Fe + Si + C. Oxygen fugacity (fO2) of the sample varies depending on these assembleges due to different O amounts in the starting materials. Chemical analyses of the recovered samples were performed using an electron microprobe. In situ X-ray diffraction experiments were conducted at 4 and 15 GPa, and up to 1873 K at BL04B1 beamline, SPring-8 synchrotron facility. Different mineral assemblages were observed depending on the redox condition of the sample. The compositions of metallic melts changes from Fe-C compositions in oxidizing conditions to Fe-Si compositions in the reducing conditions. Based on in situ X-ray diffraction experiments at 4 GPa, FeSi and SiC peaks appeared at 1373 K in the most reducing sample (iv), whereas Fe3C appeared

  9. Phase relation of C-Mg-Fe-Si-O system under various oxygen fugacity conditions at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Takahashi, S.; Ohtani, E.; Terasaki, H.; Ito, Y.; Shibazaki, Y.; Ishii, M.; Funakoshi, K.; Higo, Y.

    2010-12-01

    Many exoplanets have been found recently based on the spectroscopic observation. A carbon-rich circumstellar gas was reported to exist around “beta-Pictoris”, which has an exoplanet (Roberge et al., 2006). In such gas, carbon-enriched planet, “carbon-planet” may be formed. Carbon-bearing phase, such as carbide, carbonate, graphite and diamond are likely to compose the carbon-planet interior. Therefore, it is important to investigate phase relations of carbon-rich systems under high pressure conditions. In this study, C-enriched Mg-Si-Fe-O-C system was investigated at high pressure and temperature in order to understand the internal structure of the carbon-planet. Phase relations were studied based on 2 series of experiments; (I)textural observation and chemical analysis of the recovered sample from 4 GPa and 1873K and (II)in situ X-ray diffraction experiments under high pressure and temperature. For the starting materials, we used several different mineral assemblages, as shown below: (i) MgCO3 + Fe + Si + C, (ii) (Mg1.8,Fe0.2)SiO4 + Fe + SiO2 + C, (iii) (Mg1.8,Fe0.2)SiO4 + Fe + Si + C, (iv) MgO + Fe + SiO2 + C, (v) MgO + Fe + Si + C. Oxygen fugacity (fO2) of the sample vaies dependign on these assembleges due to different O amount in the starting materials. The sample was enclosed in graphite or MgO capsule. MgO capsule enables us to estimate fO2 in the sample based on the FeO content of the capsule contacting with the samples. Chemical analyses of the recovered samples were performed using electron microprobe. In situ X-ray diffraction experiments were conducted at 4 GPa and up to 1873 K at BL04B1 beamline, SPring-8 synchrotron facility. Different mineral assemblages and their compositions were observed in the recovered samples depending on the redox condition of the sample. The compositions of metallic melt phases changes from Fe-C composition (C = 6.9~8.2 wt.%) in oxidizing conditions (ΔIW = -2.4 ~ -1.7) to Fe-Si composition (Si = 18 wt.%) in the more

  10. Polarizability calculations on water, hydrogen, oxygen, and carbon dioxide

    NASA Technical Reports Server (NTRS)

    Nir, S.; Adams, S.; Rein, R.

    1973-01-01

    A semiclassical model of damped oscillators is used as a basis for the calculation of the dispersion of the refractive index, polarizability, and dielectric permeability in water, hydrogen, and oxygen in liquid and gaseous states, and in gaseous carbon dioxide. The absorption coefficient and the imaginary part of the refractive index are also calculated at corresponding wavelengths. A good agreement is obtained between the observed and calculated values of refractive indices, and between those of absorption coefficients in the region of absorption bands. The calculated values of oscillator strengths and damping factors are also discussed. The value of the polarizability of liquid water was about 2.8 times that of previous calculations.

  11. Effects of temperature, silicate melt composition, and oxygen fugacity on the partitioning of V, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Sn, Sb, W, Au, Pb, and Bi between sulfide phases and silicate melt

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Audétat, Andreas

    2015-08-01

    In order to assess the role of sulfide in controlling the ore metal budgets and fractionation during magmatic genesis and differentiation, the partition coefficients (D) of V, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Sn, Sb, W, Au, Pb, and Bi between sulfide liquid (SL), monosulfide solid solution (MSS), and basaltic to rhyolitic melts (SM) were determined at 900-1200 °C, 0.5-1.5 GPa, and oxygen fugacity (fO2) ranging from ∼FMQ-2 to FMQ+3, in a piston-cylinder apparatus. The DSL/SM values range from 0.4 to 2 for V, 0.5 to 3 for Mn, 80 to 580 for Co, 2300 to 18,000 for Ni, 800 to 4600 for Cu, 1 to 11 for Zn, 20 to 180 for As, 4 to 230 for Mo, 450 to 1600 for Ag, 5 to 24 for Sn, 10 to 80 for Sb, 0.03 to 0.16 for W, 2000 to 29,000 for Au, 24 to 170 for Pb, and 830 to 11,000 for Bi; whereas the DMSS/SM values range from 0.04 to 10 for V, 0.5 to 10 for Mn, 70 to 2500 for Co, 650 to 18,000 for Ni, 280 to 42,000 for Cu, 0.1 to 80 for Zn, 0.2 to 30 for As, 1 to 820 for Mo, 20 to 500 for Ag, 0.2 to 220 for Sn, 0.1 to 40 for Sb, 0.01 to 24 for W, 10 to 2000 for Au, 0.03 to 6 for Pb, and 1 to 350 for Bi. Both DMSS/SM and DSL/SM values generally increase with decreasing temperature or decreasing FeOtot content in silicate melt, except for Mo, DMSS/SM and DSL/SM of which show a clear decrease with decreasing temperature. At given temperature and FeOtot content, high oxygen fugacity appears to lead to a significant decrease in DMSS/SM of Au, Bi, Mo, and potentially As. The partitioning data obtained experimentally in this study and previous studies were fitted to an empirical equation that expresses the DMSS/SM and/or DSL/SM of a given element as a function of temperature, oxygen fugacity, and FeOtot content of the silicate melt: log (DSL/SMorDMSS/SM = d + a · 10, 000 / T + b · (ΔFMQ) + c · log (FeOmelt) in which T is temperature in K, FeOmelt denotes wt% FeOtot in silicate melt, and ΔFMQ denotes log fO2 relative to the fayalite-magnetite-quartz (FMQ) oxygen buffer. The

  12. A New Spinel-Olivine Oxybarometer: Near-Liquidus Partitioning of V between Olivine-Melt, Spinel-Melt, and Spinel-Olivine in Martian Basalt Composition Y980459 as a Function of Oxygen Fugacity

    NASA Technical Reports Server (NTRS)

    Papike, J. J.; Le, L.; Burger, P. V.; Shearer, C. K.; Bell, A. S.; Jones, J.

    2013-01-01

    Our research on valence state partitioning began in 2005 with a review of Cr, Fe, Ti, and V partitioning among crystallographic sites in olivine, pyroxene, and spinel [1]. That paper was followed by several on QUE94201 melt composition and specifically on Cr, V, and Eu partitioning between pyroxene and melt [2-5]. This paper represents the continuation of our examination of the partitioning of multivalent V between olivine, spinel, and melt in martian olivine-phyric basalts of Y980459 composition [6, 7]. Here we introduce a new, potentially powerful oxybarometer, V partitioning between spinel and olivine, which can be used when no melt is preserved in the meteorite. The bulk composition of QUE94201 was ideal for our study of martian pyroxene-phyric basalts and specifically the partitioning between pyroxene-melt for Cr, V, and Eu. Likewise, bulk composition Y980459 is ideal for the study of martian olivine-phyric basalts and specifically for olivine-melt, spinel-melt, and spinel-olivine partitioning of V as a function of oxygen fugacity.

  13. Calculation of the Lattice Frequencies of Alpha and Beta Oxygen.

    DTIC Science & Technology

    The optically active lattice frequencies of alpha- and beta-O2 have been calculated using an atom-atom Lennard - Jones potential, with and without the...agreement is obtained between the observed librational frequency and its temperature dependence in beta-O2 and the results calculated using the Lennard - Jones potential... Lennard - Jones atom-atom interaction is a satisfactory model for the potential function in solid oxygen, provided that the packing is such that electronic overlap effects are small. (Author)

  14. Transport of Pb and Zn by carboxylate complexes in basinal ore fluids and related petroleum-field brines at 100°C: the influence of pH and oxygen fugacity

    PubMed Central

    Giordano, Thomas H

    2002-01-01

    It is well established through field observations, experiments, and chemical models that oxidation (redox) state and pH exert a strong influence on the speciation of dissolved components and the solubility of minerals in hydrothermal fluids. log –pH diagrams were used to depict the influence of oxygen fugacity and pH on monocarboxylate- and dicarboxylate-transport of Pb and Zn in low-temperature (100°C) hydrothermal ore fluids that are related to diagenetic processes in deep sedimentary basins, and allow a first-order comparison of Pb and Zn transport among proposed model fluids for Mississippi Valley-type (MVT) and red-bed related base metal (RBRBM) deposits in terms of their approximate pH and conditions. To construct these diagrams, total Pb and Zn concentrations and Pb and Zn speciation were calculated as a function of log and pH for a composite ore-brine with concentrations of major elements, total sulfur, and total carbonate that approximate the composition of MVT and RBRBM model ore fluids and modern basinal brines. In addition to acetate and malonate complexation, complexes involving the ligands Cl-, HS-, H2S, and OH- were included in the model of calculated total metal concentration and metal speciation. Also, in the model, Zn and Pb are competing with the common-rock forming metals Ca, Mg, Na, Fe, and Al for the same ligands. Calculated total Pb concentration and calculated total Zn concentration are constrained by galena and sphalerite solubility, respectively. Isopleths, in log –pH space, of the concentration of Pb and concentration of Zn in carboxylate (acetate + malonate) complexes illustrate that the oxidized model fluids of T. H. Giordano (in Organic Acids in Geological Processes, ed. E. D. Pittman and M. D. Lewan, Springer-Verlag, New York, 1994, pp. 319–354) and G. M. Anderson (Econ. Geol., 1975, 70, 937–942) are capable of transporting sufficient amounts of Pb (up to 10 ppm) and Zn (up to 100 ppm) in the form of carboxylate complexes to

  15. Thermodynamic Calculation among Cerium, Oxygen, and Sulfur in Liquid Iron

    NASA Astrophysics Data System (ADS)

    Pan, Fei; Zhang, Jian; Chen, Hao-Long; Su, Yen-Hsun; Su, Yen-Hao; Hwang, Weng-Sing

    2016-10-01

    Thermodynamic calculation has been applied to predict the inclusion formation in molten SS400 steel. When the Cerium addition in liquid iron is 70 ppm and the initial Oxygen and Sulphur are both 110 ppm, the formation of oxides containing Cerium would experience the transformation from Ce2O3 to CeO2 and also the formation of sulfides containing Cerium would experience the transformation from CeS to Ce2S3 and then to Ce3S4. Below 2000 K the most thermodynamic stable matter is CeO2 and the less thermodynamic stable inclusion is CeS. Only when the amount of [O] is extremely low and the amount of [S] and [Ce] is relatively high, Ce2S3 has the possibility to form.

  16. Thermodynamic Calculation among Cerium, Oxygen, and Sulfur in Liquid Iron

    PubMed Central

    Pan, Fei; Zhang, Jian; Chen, Hao-Long; Su, Yen-Hsun; Su, Yen-Hao; Hwang, Weng-Sing

    2016-01-01

    Thermodynamic calculation has been applied to predict the inclusion formation in molten SS400 steel. When the Cerium addition in liquid iron is 70 ppm and the initial Oxygen and Sulphur are both 110 ppm, the formation of oxides containing Cerium would experience the transformation from Ce2O3 to CeO2 and also the formation of sulfides containing Cerium would experience the transformation from CeS to Ce2S3 and then to Ce3S4. Below 2000 K the most thermodynamic stable matter is CeO2 and the less thermodynamic stable inclusion is CeS. Only when the amount of [O] is extremely low and the amount of [S] and [Ce] is relatively high, Ce2S3 has the possibility to form. PMID:27767092

  17. Comparison of measured and calculated thermospheric molecular oxygen densities

    NASA Technical Reports Server (NTRS)

    Potter, W. E.; Kayser, D. C.; Brinton, H. C.; Brace, L. H.; Oppenheimer, M.

    1977-01-01

    The open source neutral mass spectrometers on the AE-C, -D, and -E satellites were equipped with a 'fly-through' mode of operation which has provided direct measurements of molecular oxygen densities over a large portion of the globe. A complementary set of O2 densities is derived by using AE ion measurements and a scheme based on the daytime ion chemistry of O2(+) in the thermosphere. A comparison of the two data sets reveals general agreement over northern latitudes during periods of relatively low Ap and F10.7. The simplifying assumptions made in the photochemical scheme require that caution be used in calculating O2, especially at high latitudes and altitudes below 200 km

  18. Calculation of muon transfer from muonic hydrogen to atomic oxygen

    SciTech Connect

    Dupays, Arnaud; Lepetit, Bruno; Beswick, J. Alberto; Rizzo, Carlo; Bakalov, Dimitar

    2003-06-01

    The muon-transfer probabilities between muonic hydrogen and an oxygen atom are calculated in a constrained geometry one-dimensional model for collision energies between 10{sup -6} and 10{sup 3} eV. For relative translational energies below 10{sup -1} eV, for which the de Broglie wavelength (>1 Aa) is much larger than the characteristic distance of the potential interaction ({approx}0.1 Aa), the problem corresponds to an ultracold collision. The close-coupling time-independent quantum equations are written in terms of hyperspherical coordinates and a diabatic-by-sectors basis set. The muon-transfer probabilities are qualitatively interpreted in terms of a model involving two Landau-Zener crossings together with the threshold energy dependence. Based on this analysis, a simple procedure to estimate the energy dependence of the muon-transfer rate in three dimensions is proposed. These estimated rates are discussed in the light of previous model calculations and available experimental data for this process. It is concluded that the high transfer rates at epithermal energies inferred from experiments are unlikely to be correct.

  19. Fugacity and concentration gradients in a gravity field

    NASA Astrophysics Data System (ADS)

    May, C. E.

    1986-07-01

    Equations are reviewed which show that at equilibrium fugacity and concentration gradients can exist in gravitational fields. At equilibrium, the logarithm of the ratio of the fugacities of a species at two different locations in a gravitational field is proportional to the difference in the heights of the two locations and the molecular weight of the species. An analogous relation holds for the concentration ratios in a multicomponent system. The ratio is calculated for a variety of examples. The kinetics for the general process are derived, and the time required to approach equilibrium is calculated for several systems. The following special topics are discussed: ionic solutions, polymers, multiphase systems, hydrostatic pressure, osmotic pressure, and solubility gradients in a gravity field.

  20. Fugacity and concentration gradients in a gravity field

    NASA Technical Reports Server (NTRS)

    May, C. E.

    1986-01-01

    Equations are reviewed which show that at equilibrium fugacity and concentration gradients can exist in gravitational fields. At equilibrium, the logarithm of the ratio of the fugacities of a species at two different locations in a gravitational field is proportional to the difference in the heights of the two locations and the molecular weight of the species. An analogous relation holds for the concentration ratios in a multicomponent system. The ratio is calculated for a variety of examples. The kinetics for the general process are derived, and the time required to approach equilibrium is calculated for several systems. The following special topics are discussed: ionic solutions, polymers, multiphase systems, hydrostatic pressure, osmotic pressure, and solubility gradients in a gravity field.

  1. Fugacity of H2O from 0° to 350°C at the liquid-vapor equilibrium and at 1 atmosphere

    USGS Publications Warehouse

    Hass, John L.

    1970-01-01

    The fugacity and fugacity coefficient of H2O at the liquid-vapor equilibrium, the fugacity and the Gibbs free energy of formation of H2O at 1 atm (1.01325 bars) total pressure have been calculated from published data on the physical and thermodynamic properties of H2O and are presented at ten-degree intervals from 0° to 350°C.

  2. Assessment of the air-soil partitioning of polycyclic aromatic hydrocarbons in a paddy field using a modified fugacity sampler.

    PubMed

    Wang, Yan; Luo, Chunling; Wang, Shaorui; Liu, Junwen; Pan, Suhong; Li, Jun; Ming, Lili; Zhang, Gan; Li, Xiangdong

    2015-01-06

    Rice, one of the most widely cultivated crops, has received great attention in contaminant uptake from soil and air, especially for the special approaches used for its cultivation. The dry-wet alternation method can influence the air-soil partitioning of semivolatile organic compounds (SVOCs) in the paddy ecosystem. Here, we modified a fugacity sampler to investigate the air-surface in situ partitioning of ubiquitous polycyclic aromatic hydrocarbons (PAHs) at different growth stages in a suburban paddy field in South China. The canopy of rice can form a closed space, which acts like a chamber that can force the air under the canopy to equilibrate with the field surface. When we compared the fugacities calculated using a fugacity model of the partition coefficients to the measured fugacities, we observed similar trends in the variation, but significantly different values between different growing stages, especially during the flooding stages. However, the measured and calculated fugacity fractions were comparable when uncertainties in our calculations were considered, with the exception of the high molecular weight (HMW) PAHs. The measured fugacity fractions suggested that the HMW PAHs were also closed to equilibrium between the paddy field and atmosphere. The modified fugacity sampler provided a novel way of accurately determining the in situ air-soil partitioning of SVOCs in a wet paddy field.

  3. Atomic oxygen flux and fluence calculation for Long Duration Exposure Facility (LDEF)

    NASA Technical Reports Server (NTRS)

    Bourassa, Roger J.; Gillis, James R.

    1991-01-01

    The LDEF mission was to study the effects of the space environment on various materials over an extended period of time. One of the important factors for materials degradation in low earth orbit is the atomic oxygen fluxes and fluences experienced by the materials. These fluxes and fluences are a function of orbital parameters, solar and geomagnetic activity, and material surface orientation. Calculations of atomic oxygen fluences and fluxes for the LDEF mission are summarized. Included are descriptions of LDEF orbital parameters, solar and geomagnetic data, computer code FLUXAV, which was used to perform calculations of fluxes and fluences, along with a discussion of the calculated fluxes and fluences.

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

    SciTech Connect

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

    2015-01-21

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

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

    SciTech Connect

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

    2015-03-01

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

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

    DOE PAGES

    Aidhy, Dilpuneet S.; Liu, Bin; Zhang, Yanwen; ...

    2015-01-21

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

  7. Oxygen vacancies in amorphous-Ta2O5 from first-principles calculations

    NASA Astrophysics Data System (ADS)

    Lee, Jihang; Kioupakis, Emmanouil; Lu, Wei

    Oxygen vacancies are thought to play a crucial role in the electrical and optical properties of tantalum pentoxide (Ta2O5) devices. Even though numerous experimental studies on oxygen vacancies in Ta2O5 exist, experimentally detected defects are ambiguously identified due to the absence of an accurate and conclusive theoretical analysis. We investigate oxygen vacancies in amorphous Ta2O5 with first-principles calculations based on hybrid density functional theory. The calculated thermodynamic and optical transition levels of stable oxygen vacancies are in good agreement with measured values from a variety of experimental methods, providing conclusive clues for the identification of the defect states observed in experiments. We determine the concentration of oxygen vacancies and their dominant oxidation state as a function of growth conditions. We analyze the characteristics of extra electrons introduced by donor-like oxygen vacancies, which include the formation of polarons. Our results provide insight into the fundamental properties of oxygen vacancies in Ta2O5, which is essential to controlling the properties of films and optimize the performance of devices. This research was supported by the AFOSR through MURI grant FA9550-12-1-0038 and the National Science Foundation CAREER award through Grant No. DMR-1254314. Computational resources were provided by the DOE NERSC facility.

  8. Bedside calculation of hemodynamic parameters with a hand held programmable calculator. Part II: Programs for hemodynamic and oxygen transport parameters computation.

    PubMed

    Laurent, M

    1980-01-01

    Two programs calculating oxygen transport parameters and hemodynamic values respectively are described. They may be used indifferently with HP 67 or HP 97 Hewlett Packard calculators. (Acta anaesth. belg., 1980, 31, 53-59).

  9. Influence of oxygen vacancies on the dielectric properties of hafnia: First-principles calculations

    NASA Astrophysics Data System (ADS)

    Cockayne, Eric

    2007-03-01

    First-principles calculations were used to study the effects of neutral and 2+ charged oxygen vacancies on the dielectric properties of crystalline HfO2 . In agreement with previous results, the neutral vacancy is more stable on four fold-coordinated site, while the charged vacancy is more stable on a three fold-coordinated site. For both vacancy positions, HfO2 remains insulating whether the vacancy is neutral or in the 2+ charge state. The dynamical matrix, Born effective charges, and electronic dielectric tensor were calculated for each structure. With one oxygen vacancy per 64 oxygen atoms, the static dielectric constant κs is increased by 1%-2% for neutral vacancies and suppressed by 1%-3% for 2+ charged vacancies, with the larger changes for three fold-coordinated vacancies. The exact result in the case of a charged vacancy depends on how the neutralizing charge necessary for macroscopic charge neutrality is modeled. The increase in κs for neutral oxygen vacancies arises from an enhancement of the electronic dielectric response due to a pair of electrons occupying an easily polarizable F -center defect state. The suppression in κs for charged oxygen vacancies is due to phonon hardening, which reduces the ionic response. No evidence is found for characteristic localized phonons induced by oxygen vacancies that could be detected by infrared or Raman spectroscopy.

  10. Dioxygen molecule adsorption and oxygen atom diffusion on clean and defective aluminum(111) surface using first principles calculations

    NASA Astrophysics Data System (ADS)

    Guiltat, Mathilde; Brut, Marie; Vizzini, Sébastien; Hémeryck, Anne

    2017-03-01

    First principles calculations are conducted to investigate kinetic behavior of oxygen species at the surface of clean and defective Al(111) substrate. Oxygen island, aluminum vacancy, aluminum sub-vacancy, aluminum ad-atom and aluminum terraces defects are addressed. Adsorption of oxygen molecule is first performed on all these systems resulting in dissociated oxygen atoms in main cases. The obtained adsorbed configurations are then picked to study the behavior of atomic oxygen specie and get a detailed understanding on the effect of the local environment on the ability of the oxygen atom to diffuse on the surface. We pointed out that local environment impacts energetics of oxygen atom diffusion. Close packed oxygen island, sub-vacancy and ad-atoms favor oxygen atom stability and decrease mobility of oxygen atom on the surface, to be seen as surface area for further nucleation of oxygen island.

  11. Consistent calculation of aquatic gross production from oxygen triple isotope measurements

    NASA Astrophysics Data System (ADS)

    Kaiser, J.

    2011-04-01

    Oxygen triple isotope measurements can be used to calculate aquatic gross oxygen production rates. Past studies have emphasised the appropriate definition of the 17O excess and often used an approximation to derive production rates from the 17O excess. Here, I show that the calculation can be phrased more consistently and without any approximations using the relative 17O/16O and 18O/16O isotope ratio differences directly. The 17O excess is merely a mathematical construct and the derived production rate is independent of its definition, provided all calculations are performed with a consistent definition. I focus on the mixed layer, but also show how time series of triple oxygen measurements below the mixed layer can be used to derive gross production. In the calculation of mixed layer productivity, I explicitly include isotopic fractionation during gas invasion and evasion, which requires the oxygen supersaturation s to be measured as well. I also suggest how bubble injection could be considered in the same mathematical framework. I distinguish between concentration steady state and isotopic steady state and show that only the latter needs to be assumed in the calculation. It is even possible to derive an estimate of the net production rate in the mixed layer that is independent of the assumption of concentration steady state. I review measurements of the parameters required for the calculation of gross production rates and show how their systematic uncertainties as well as the use of different published calculation methods can cause large variations in the production rates for the same underlying isotope ratios. In particular, the 17O excess of dissolved O2 in equilibrium with atmospheric O2 and the 17O excess of photosynthetic O2 need to be re-measured. Because of these uncertainties, all calculation parameters should always be fully documented and the measured isotope ratio differences as well as the oxygen supersaturation should be permanently archived, so that

  12. Accelerated materials design of fast oxygen ionic conductors based on first principles calculations

    NASA Astrophysics Data System (ADS)

    He, Xingfeng; Mo, Yifei

    Over the past decades, significant research efforts have been dedicated to seeking fast oxygen ion conductor materials, which have important technological applications in electrochemical devices such as solid oxide fuel cells, oxygen separation membranes, and sensors. Recently, Na0.5Bi0.5TiO3 (NBT) was reported as a new family of fast oxygen ionic conductor. We will present our first principles computation study aims to understand the O diffusion mechanisms in the NBT material and to design this material with enhanced oxygen ionic conductivity. Using the NBT materials as an example, we demonstrate the computation capability to evaluate the phase stability, chemical stability, and ionic diffusion of the ionic conductor materials. We reveal the effects of local atomistic configurations and dopants on oxygen diffusion and identify the intrinsic limiting factors in increasing the ionic conductivity of the NBT materials. Novel doping strategies were predicted and demonstrated by the first principles calculations. In particular, the K doped NBT compound achieved good phase stability and an order of magnitude increase in oxygen ionic conductivity of up to 0.1 S cm-1 at 900 K compared to the experimental Mg doped compositions. Our results provide new avenues for the future design of the NBT materials and demonstrate the accelerated design of new ionic conductor materials based on first principles techniques. This computation methodology and workflow can be applied to the materials design of any (e.g. Li +, Na +) fast ion-conducting materials.

  13. Inverse calculation of biochemical oxygen demand models based on time domain for the tidal Foshan River.

    PubMed

    Er, Li; Xiangying, Zeng

    2014-01-01

    To simulate the variation of biochemical oxygen demand (BOD) in the tidal Foshan River, inverse calculations based on time domain are applied to the longitudinal dispersion coefficient (E(x)) and BOD decay rate (K(x)) in the BOD model for the tidal Foshan River. The derivatives of the inverse calculation have been respectively established on the basis of different flow directions in the tidal river. The results of this paper indicate that the calculated values of BOD based on the inverse calculation developed for the tidal Foshan River match the measured ones well. According to the calibration and verification of the inversely calculated BOD models, K(x) is more sensitive to the models than E(x) and different data sets of E(x) and K(x) hardly affect the precision of the models.

  14. Technical note: Consistent calculation of aquatic gross production from oxygen triple isotope measurements

    NASA Astrophysics Data System (ADS)

    Kaiser, J.

    2011-07-01

    Oxygen triple isotope measurements can be used to calculate aquatic gross oxygen production rates. Past studies have emphasised the appropriate definition of the 17O excess and often used an approximation to derive production rates from the 17O excess. Here, I show that the calculation can be phrased more consistently and without any approximations using the relative 17O/16O and 18O/16O isotope ratio differences (delta values) directly. I call this the "dual delta method". The 17O excess is merely a mathematical construct and the derived production rate is independent of its definition, provided all calculations are performed with a consistent definition. I focus on the mixed layer, but also show how time series of triple isotope measurements below the mixed layer can be used to derive gross production. In the calculation of mixed layer productivity, I explicitly include isotopic fractionation during gas invasion and evasion, which requires the oxygen supersaturation s to be measured as well. I also suggest how bubble injection could be considered in the same mathematical framework. I distinguish between concentration steady state and isotopic steady state and show that only the latter needs to be assumed in the calculation. It is even possible to derive an estimate of the net production rate in the mixed layer that is independent of the assumption of concentration steady state. I review measurements of the parameters required for the calculation of gross production rates and show how their systematic uncertainties as well as the use of different published calculation methods can cause large variations in the production rates for the same underlying isotope ratios. In particular, the 17O excess of dissolved O2 in equilibrium with atmospheric O2 and the 17O excess of photosynthetic O2 need to be re-measured. Because of these uncertainties, all calculation parameters should always be fully documented and the measured relative isotope ratio differences as well as the

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

    PubMed

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

    2017-03-24

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

  16. Electronic Structure Calculations of an Oxygen Vacancy in KH2PO4

    SciTech Connect

    Liu, C S; Hou, C J; Kioussis, N; Demos, S; Radousky, H

    2005-02-18

    We present first-principles total-energy density-functional theory electronic structure calculations for the neutral and charge states of an oxygen vacancy in KH{sub 2}PO{sub 4} (KDP). Even though the overall DOS profiles for the defective KDP are quite similar to those of the perfect KDP, the oxygen vacancy in the neutral and +1 charge states induces defect states in the band gap. For the neutral oxygen vacancy, the gap states are occupied by two electrons. The difference between the integral of the total density of states (DOS) and the sum of the DOS projected on the atoms of 0.98 |e|, indicates that one of the two electrons resulting from the removal of the oxygen atom is trapped in the vacancy, while the other tends to delocalize in the neighboring atoms. For the +1 charge oxygen vacancy, the addition of the hole reduces the occupation of the filled gap-states in the neutral case from two to one electron and produces new empty states in the gap. The new empty gap states are very close to the highest occupied states, leading to a dramatic decrease of the band gap. The difference between the integral of the total DOS and the sum of the DOS projected on the atoms is 0.56 |e|, which implies that more than 56% of the redundant electron is trapped in the oxygen vacancy, and 44% spreads over the neighboring atoms. In sharp contrast, no defect states appear in the energy gap for the +2 charge O vacancy. Thus, the addition of the two holes completely compensates the two redundant electrons, and removes in turn the occupied gap states in the neutral case.

  17. Time efficient way to calculate oxygen transfer areas and power input in cylindrical disposable shaken bioreactors.

    PubMed

    Klöckner, Wolf; Lattermann, Clemens; Pursche, Franz; Büchs, Jochen; Werner, Sören; Eibl, Dieter

    2014-01-01

    Disposable orbitally shaken bioreactors are a promising alternative to stirred or wave agitated systems for mammalian and plant cell cultivation, because they provide a homogeneous and well-defined liquid distribution together with a simple and cost-efficient design. Cultivation conditions in the surface-aerated bioreactors are mainly affected by the size of the volumetric oxygen transfer area (a) and the volumetric power input (P∕VL ) that both result from the liquid distribution during shaking. Since Computational Fluid Dynamics (CFD)-commonly applied to simulate the liquid distribution in such bioreactors-needs high computing power, this technique is poorly suited to investigate the influence of many different operating conditions in various scales. Thus, the aim of this paper is to introduce a new mathematical model for calculating the values of a and P∕VL for liquids with water-like viscosities. The model equations were derived from the balance of centrifugal and gravitational forces exerted during shaking. A good agreement was found among calculated values for a and P∕VL , CFD simulation values and empirical results. The newly proposed model enables a time efficient way to calculate the oxygen transfer areas and power input for various shaking frequencies, filling volumes and shaking and reactor diameters. All these parameters can be calculated fast and with little computing power.

  18. Experimental determination of coexisting iron titanium oxides in the systems FeTiAlO, FeTiAlMgO, FeTiAlMnO, and FeTiAlMgMnO at 800 and 900°C, 1 4 kbar, and relatively high oxygen fugacity

    NASA Astrophysics Data System (ADS)

    Evans, Bernard W.; Scaillet, Bruno; Kuehner, Scott M.

    2006-08-01

    A synthetic, low-melting rhyolite composition containing TiO2 and iron oxide, with further separate additions of MgO, MnO, and MgO + MnO, was used in hydrothermal experiments to crystallize Ilm-Hem and Usp-Mt solid solutions at 800 and 900°C under redox conditions slightly below nickel nickel oxide (NNO) to ≈ 3 log_{10} f_{{{text{O}}2}} units above the NNO oxygen buffer. These experiments provide calibration of the FeTi-oxide thermometer + oxygen barometer at conditions of temperature and oxygen fugacity poorly covered by previous equilibrium experiments. Isotherms for our data in Roozeboom diagrams of projected %usp vs. %ilm show a change in slope at ≈ 60% ilm, consistent with the second-order transition from FeTi-ordered Ilm to FeTi-disordered Ilm-Hem. This feature of the system accounts for some, but not all, of the differences from earlier thermodynamic calibrations of the thermobarometer. In rhyolite containing 1.0 wt.% MgO, 0.8 wt.% MnO, or MgO + MnO, Usp-Mt crystallized with up to 14% of aluminate components, and Ilm-Hem crystallized with up to 13% geikielite component and 17% pyrophanite component. Relative to the FeTiAlO system, these components displace the ferrite components in Usp-Mt, and the hematite component in Ilm-Hem. As a result, projected contents of ulvöspinel and ilmenite are increased. These changes are attributed to increased non-ideality along joins from end-member hematite and magnetite to their respective Mg- and Mn-bearing titanate and aluminate end-members. The compositional shifts are most pronounced in Ilm-Hem in the range Ilm50 80, a solvus region where the chemical potentials of the hematite and ilmenite components are nearly independent of composition. The solvus gap widens with addition of Mg and even further with Mn. The Bacon Hirschmann correlation of Mg/Mn in Usp-Mt and coexisting Ilm-Hem is displaced toward increasing Mg/Mn in ilmenite with passage from ordered ilmenite to disordered hematite. Orthopyroxene and biotite

  19. Theoretical study of atomic oxygen on gold surface by Hückel theory and DFT calculations.

    PubMed

    Sun, Keju; Kohyama, Masanori; Tanaka, Shingo; Takeda, Seiji

    2012-09-27

    It is fundamental to understand the behavior of atomic oxygen on gold surfaces so as to elucidate the mechanism of nano gold catalysts for low-temperature CO oxidation reactions since the atomic oxygen on gold system is an important intermediate involved in both the processes of O(2) dissociation and CO oxidation. We performed theoretical analysis of atomic oxygen adsorption on gold by using Hückel theory. It is found that formation of linear O-Au-O structure on Au surfaces greatly stabilizes the atomic oxygen adsorption due to stronger bond energy and bond order, which is confirmed subsequently by density functional theory (DFT) calculations. The linear O-Au-O structure may explain the surprising first order kinetics behavior of O(2) desorption from gold surfaces. This view of the linear O-Au-O structure as the natural adsorption status is quite different from the conventional view, which may lead to new understanding toward the reaction mechanism of low-temperature CO oxidation reaction on nano gold catalysts.

  20. Electronic structure and excitations in oxygen deficient CeO2-δ from DFT calculations

    NASA Astrophysics Data System (ADS)

    Jarlborg, T.; Barbiellini, B.; Lane, C.; Wang, Yung Jui; Markiewicz, R. S.; Liu, Zhi; Hussain, Zahid; Bansil, A.

    2014-04-01

    The electronic structures of supercells of CeO2-δ have been calculated within the density functional theory (DFT). The equilibrium properties such as lattice constants, bulk moduli, and magnetic moments are well reproduced by the generalized gradient approximation (GGA). Electronic excitations are simulated by robust total-energy calculations for constrained states with atomic core holes or valence holes. Pristine ceria CeO2 is found to be a nonmagnetic insulator with magnetism setting in as soon as oxygens are removed from the structure. In the ground state of defective ceria, the Ce-f majority band resides near the Fermi level but appears at about 2 eV below the Fermi level in photoemission spectroscopy experiments due to final-state effects. We also tested our computational method by calculating threshold energies in Ce-M5 and O-K x-ray absorption spectroscopy and comparing theoretical predictions with the corresponding measurements. Our result that f electrons reside near the Fermi level in the ground state of oxygen-deficient ceria is crucial for understanding the catalytic properties of CeO2 and related materials.

  1. Nitrogen-broadened lineshapes in the oxygen A-band: Experimental results and theoretical calculations

    NASA Astrophysics Data System (ADS)

    Predoi-Cross, Adriana; Holladay, Christopher; Heung, Henry; Bouanich, Jean-Pierre; Mellau, Georg Ch.; Keller, Reimund; Hurtmans, Daniel R.

    2008-09-01

    We report measurements for N 2-broadening, pressure-shift and line mixing coefficients for 55 oxygen transitions in the A-band retrieved using a multispectrum fitting technique. Nineteen laboratory absorption spectra were recorded at 0.02 cm -1 resolution using a multi-pass absorption cell with path length of 1636.9 cm and the IFS 120 Fourier transform spectrometer located at Justus-Liebig-University in Giessen, Germany. The total sample pressures ranged from 8.8 to 3004.5 Torr with oxygen volume mixing ratios in nitrogen ranging between 0.057 and 0.62. An Exponential Power Gap (EPG) scaling law was used to calculate the N 2-broadening and N 2-line mixing coefficients. The line broadening and shift coefficients for the A-band of oxygen self-perturbed and perturbed by N 2 are modeled using semiclassical calculations based on the Robert-Bonamy formalism and two intermolecular potentials. These potentials involve electrostatic contributions including the hexadecapole moment of the molecules and (a) a simple dispersion contribution with one adjustable parameter to fit the broadening coefficients or (b) the atom-atom Lennard-Jones model without such adjustable parameters. The first potential leads to very weak broadening coefficients for high J transitions whereas the second potential gives much more improved results at medium and large J values, in reasonable agreement with the experimental data. For the line shifts which mainly arise in our calculation from the electronic state dependence of the isotropic potential, their general trends with increasing J values can be well predicted, especially from the first potential. From the theoretical results, we have derived air-broadening and air-induced shift coefficients with an agreement comparable to that obtained for O 2-O 2 and O 2-N 2.

  2. Thermodynamic calculations of oxygen self-diffusion in mixed-oxide nuclear fuels

    DOE PAGES

    Parfitt, David C.; Cooper, Michael William; Rushton, Michael J.D.; ...

    2016-07-29

    Mixed-oxide fuels containing uranium with thorium and/or plutonium may play an important part in future nuclear fuel cycles. There are, however, significantly less data available for these materials than conventional uranium dioxide fuel. In the present study, we employ molecular dynamics calculations to simulate the elastic properties and thermal expansivity of a range of mixed oxide compositions. These are then used to support equations of state and oxygen self-diffusion models to provide a self-consistent prediction of the behaviour of these mixed oxide fuels at arbitrary compositions.

  3. Oxygen- and hydroxyl-edge termination of silicene nanoribbons studied by first-principles calculations

    NASA Astrophysics Data System (ADS)

    Li, Rui; Liu, Zhong-Li; Gu, Yanhong; Zhang, Weiying; Tan, Yonggang

    2016-05-01

    The geometrical structures and electronic properties of the armchair- and zigzag-edge silicene nanoribbons (SiNRs), terminated with oxygen and hydroxyl (ZSiNR-O, ZSiNR-OH, ASiNR-O, ASiNR-OH), have been investigated by using the first-principles method. It is found that the silicene edges are rippled upon the oxygen termination. On one edge of ZSiNR-O, the neighboring Si-O bonds move concordantly right (left) from the silicene plane, while on one edge of ASiNR-O, the neighboring Si-O bonds respectively move right and left to result in larger rippled amplitudes. Comparably, the influence of OH-termination on the silicene edge is small, inducing smaller rippled edges. The electronic structure calculations show that the px electrons of oxygen on the rippled edges of ZSiNR-O sp3 hybridize with the edge Si atoms, forming one more bands. The band gaps of the ASiNR-O and ASiNR-OH also obey the three-family behavior, due to the quantum confinement and the crucial effect of the edges. For ASiNR-OH, by taking account of the new atom chains formed by the hydrogen bonds of the neighboring OHs, the band gaps follow the same hierarchy of Δ3 p >Δ3 p - 1 >Δ3 p - 2 with those of ASiNR-Os.

  4. Temperature Compensation of Oxygen Sensing Films Utilizing a Dynamic Dual Lifetime Calculation Technique

    PubMed Central

    Collier, Bradley B.; McShane, Michael J.

    2014-01-01

    With advances to chemical sensing, methods for compensation of errors introduced by interfering analytes are needed. In this work, a dual lifetime calculation technique was developed to enable simultaneous monitoring of two luminescence decays. Utilizing a windowed time-domain luminescence approach, the response of two luminophores is separated temporally. The ability of the dual dynamic rapid lifetime determination (DDRLD) approach to determine the response of two luminophores simultaneously was investigated through mathematical modeling and experimental testing. Modeling results indicated that lifetime predictions will be most accurate when the ratio of the lifetimes from each luminophore is at least three and the ratio of intensities is near unity. In vitro experiments were performed using a porphyrin that is sensitive to both oxygen and temperature, combined with a temperature-sensitive inorganic phosphor used for compensation of the porphyrin response. In static experiments, the dual measurements were found to be highly accurate when compared to single-luminophore measurements—statistically equivalent for the long lifetime emission and an average difference of 2% for the short lifetimes. Real-time testing with dynamic windowing was successful in demonstrating dual lifetime measurements and temperature compensation of the oxygen sensitive dye. When comparing the actual oxygen and temperature values with predictions made using a dual calibration approach, an overall difference of less than 1% was obtained. Thus, this method enables rapid, accurate extraction of multiple lifetimes without requiring computationally intense curve fitting, providing a significant advancement toward multi-analyte sensing and imaging techniques. PMID:26566384

  5. Partitioning of Eu between augite and a highly spiked martian basalt composition as a function of oxygen fugacity (IW-1 to QFM): Determination of Eu[superscript 2+]/Eu[superscript 3+] ratios by XANES

    SciTech Connect

    Karner, J.M.; Papike, J.J.; Sutton, S.R.; Burger, P.V.; Shearer, C.K.; Le, L.; Newville, M.; Choi, Y.

    2010-03-16

    We have determined D{sub Eu} between augite and melt in samples that crystallized from a highly spiked martian basalt composition at four f{sub O{sub 2}} conditions. D{sub Eu} augite/melt shows a steady increase with f{sub O{sub 2}} from 0.086 at IW-1 to 0.274 at IW+3.5. This increase is because Eu{sup 3+} is more compatible than Eu{sup 2+} in the pyroxene structure; thus increasing f{sub O{sub 2}} leads to greater Eu{sup 3+}/Eu{sup 2+} in the melt and more Eu (total) can partition into the crystallizing pyroxene. This interpretation is supported by direct determinations of Eu valence state by XANES, which show a steady increase of Eu{sup 3+}/Eu{sup 2+} with increasing f{sub O{sub 2}} in both pyroxene (0.38 to 14.6) and glass (0.20 to 12.6) in the samples. Also, pyroxene Eu{sup 3+}/Eu{sup 2+} is higher than that of adjacent glass in all the samples, which verifies that Eu{sup 3+} is more compatible than Eu{sup 2+} in the pyroxene structure. Combining partitioning data with XANES data allows for the calculation of specific valence state D-values for augite/melt where D{sub Eu{sup 3+}} = 0.28 and D{sub Eu{sup 2+}} = 0.07.

  6. Dual-wavelength retinal images denoising algorithm for improving the accuracy of oxygen saturation calculation

    NASA Astrophysics Data System (ADS)

    Xian, Yong-Li; Dai, Yun; Gao, Chun-Ming; Du, Rui

    2017-01-01

    Noninvasive measurement of hemoglobin oxygen saturation (SO2) in retinal vessels is based on spectrophotometry and spectral absorption characteristics of tissue. Retinal images at 570 and 600 nm are simultaneously captured by dual-wavelength retinal oximetry based on fundus camera. SO2 is finally measured after vessel segmentation, image registration, and calculation of optical density ratio of two images. However, image noise can dramatically affect subsequent image processing and SO2 calculation accuracy. The aforementioned problem remains to be addressed. The purpose of this study was to improve image quality and SO2 calculation accuracy by noise analysis and denoising algorithm for dual-wavelength images. First, noise parameters were estimated by mixed Poisson-Gaussian (MPG) noise model. Second, an MPG denoising algorithm which we called variance stabilizing transform (VST) + dual-domain image denoising (DDID) was proposed based on VST and improved dual-domain filter. The results show that VST + DDID is able to effectively remove MPG noise and preserve image edge details. VST + DDID is better than VST + block-matching and three-dimensional filtering, especially in preserving low-contrast details. The following simulation and analysis indicate that MPG noise in the retinal images can lead to erroneously low measurement for SO2, and the denoised images can provide more accurate grayscale values for retinal oximetry.

  7. The effects of sulfur, silicon, water, and oxygen fugacity on solubility and metal-silicate partitioning of carbon at 3 GPa and 1600 °C - Implications for core-mantle differentiation and degassing of magma oceans and reduced planetary mantles

    NASA Astrophysics Data System (ADS)

    Li, Y.; Dasgupta, R.; Tsuno, K.

    2014-12-01

    The partition coefficient of carbon between Fe-rich alloy melt and silicate melt, and solubility of C-O-H volatiles in reduced silicate melts are key to understand the origin and distribution of carbon in different planetary reservoirs and subsequent evolution of volatiles in magma oceans (MO) and silicate mantles. In this study, three sets of graphite-saturated experiments have been performed at 3 GPa and 1600 °C to investigate the effects of oxygen fugacity (fO2), sulfur, silicon, and water on the dissolution and partitioning of carbon between Fe-rich alloy melt and silicate melt. The results show that the presence of 0-5 wt% sulfur in alloy melt does not have considerable effect on carbon solubility (~5.6 wt%) in alloy melt, whereas the presence of 0-10 wt% silicon decreases it from ~5.6 wt% to 1.8 wt%. Carbon solubility (11-192 ppm) in silicate melt is strongly controlled by fO2 and the bulk water content. Decreasing fO2 from IW-0.6 to IW-4.7 or increasing bulk water content from 0.07 to 0.55 wt% results in significant increase of carbon solubility in silicate melt. Raman and FTIR spectroscopy of silicate glasses show that the carbon species is mostly methane, confirmed by the positive correlation between carbon and non-hydroxyl hydrogen in silicate melt. The decreases from 4600 to 180 with decreasing fO2 or increasing bulk water in silicate melt. In addition, increasing Si in metallic alloy melt also decreases . Our results show that fO2 and silicate melt bulk water contents play an important role in the fractionation of carbon in planetary MO. A reduced, hydrous MO may have led to a considerable fraction of carbon retained in the silicate mantle, whereas an oxidized, dry MO may have lost almost its entire carbon to the core. If delivery of bulk Earth carbon predominantly occurred after >90% of accretion, i.e., in a relatively oxidized MO (IW-2 to IW-1), then with applicable >1000, most carbon would also enter the segregating core. Finally, the predominance

  8. Nonlinear waves in dense dusty plasmas with high fugacity

    NASA Astrophysics Data System (ADS)

    Rao, N. N.; Shukla, P. K.

    2001-01-01

    Nonlinear propagation of small, but finite, amplitude electrostatic dust waves has been investigated in the low as well as high fugacity regimes by deriving the corresponding Boussinesq equation which, for unidirectional propagation, reduces to the Korteweg-de Vries equation. The dust-acoustic wave (DAW) solitons are shown to correspond to the tenuous (low fugacity) dusty plasmas, while in the dense (high fugacity) regime the solitons are associated with the dust-Coulomb waves (DCWs). Unlike the DAW solitons which are (dust) density compressional and supersonic, the DCW solitons are (dust) density rarefactive and propagate with super-Coulombic speeds.

  9. Stratification calculations in a heated cryogenic oxygen storage tank at zero gravity

    NASA Technical Reports Server (NTRS)

    Shuttles, J. T.; Smith, G. L.

    1971-01-01

    A cylindrical one-dimensional model of the Apollo cyrogenic oxygen storage tank has been developed to study the effect of stratification in the tank. Zero gravity was assumed, and only the thermally induced motions were considered. The governing equations were derived from conservation laws and solved on a digital computer. Realistic thermodynamic and transport properties were used. Calculations were made for a wide range of conditions. The results show the fluid behavior to be dependent on the quantity in the tank or equivalently the bulk fluid temperature. For high quantities (low temperatures) the tank pressure rose rapidly with heat addition, the heater temperature remained low, and significant pressure drop potentials accrued. For low quantities the tank pressure rose more slowly with heat addition and the heater temperature became high. A high degree of stratification resulted for all conditions; however, the stratified region extended appreciably into the tank only for the lowest tank quantity.

  10. A refined method for calculating paleotemperatures from linear correlations in bamboo coral carbon and oxygen isotopes

    NASA Astrophysics Data System (ADS)

    Saenger, Casey; Watkins, James M.

    2016-06-01

    Bamboo corals represent an emerging paleoclimate archive with the potential to record variability at intermediate depths throughout much of the global ocean. Realizing this potential has been complicated by biologically mediated vital effects, which are evident in linear correlations of skeletal carbon (δ13C) and oxygen (δ18O) isotope composition. Previous efforts to develop a bamboo coral δ18O paleothermometer by accounting for such vital effects have not been completely successful as they still rely on empirical calibrations that are offset from the temperature dependence of abiogenic experiments. Here we describe an approach that better corrects for bamboo coral vital effects and allows paleotemperatures to be calculated directly from the abiogenic temperature dependence. The success of the method lies in calculating apparent equilibrium carbon and oxygen isotope fractionation at the temperature, pH, and growth rate of each coral, as well as in the use of model II regressions. Rigorous propagation of uncertainty suggests typical errors of ±2-3°C, but in select cases errors as low as ±0.65°C can be achieved for densely sampled and strongly correlated data sets. This lower limit approaches the value attributed to uncertainty in pH and growth rate estimates alone, as predicted by a series of pseudoproxy experiments. The incorporation of isotopically light metabolic CO2 appears to be negligible in most Pacific corals, but may be significant in Atlantic specimens, potentially requiring an additional correction. The success of the method therefore hinges on how well complex environmental systems and biomineralization strategies are constrained, with the most reliable temperatures occurring when calcifying fluid pH, growth rate, and incorporation of metabolic carbon into skeletal calcite are constrained using multiple geochemical proxies.

  11. Estimating the uncertainty in thermochemical calculations for oxygen-hydrogen combustors

    NASA Astrophysics Data System (ADS)

    Sims, Joseph David

    The thermochemistry program CEA2 was combined with the statistical thermodynamics program PAC99 in a Monte Carlo simulation to determine the uncertainty in several CEA2 output variables due to uncertainty in thermodynamic reference values for the reactant and combustion species. In all, six typical performance parameters were examined, along with the required intermediate calculations (five gas properties and eight stoichiometric coefficients), for three hydrogen-oxygen combustors: a main combustor, an oxidizer preburner and a fuel preburner. The three combustors were analyzed in two different modes: design mode, where, for the first time, the uncertainty in thermodynamic reference values---taken from the literature---was considered (inputs to CEA2 were specified and so had no uncertainty); and data reduction mode, where inputs to CEA2 did have uncertainty. The inputs to CEA2 were contrived experimental measurements that were intended to represent the typical combustor testing facility. In design mode, uncertainties in the performance parameters were on the order of 0.1% for the main combustor, on the order of 0.05% for the oxidizer preburner and on the order of 0.01% for the fuel preburner. Thermodynamic reference values for H2O were the dominant sources of uncertainty, as was the assigned enthalpy for liquid oxygen. In data reduction mode, uncertainties in performance parameters increased significantly as a result of the uncertainties in experimental measurements compared to uncertainties in thermodynamic reference values. Main combustor and fuel preburner theoretical performance values had uncertainties of about 0.5%, while the oxidizer preburner had nearly 2%. Associated experimentally-determined performance values for all three combustors were 3% to 4%. The dominant sources of uncertainty in this mode were the propellant flowrates. These results only apply to hydrogen-oxygen combustors and should not be generalized to every propellant combination. Species for

  12. Dust-Coulomb and dust-acoustic wave propagation in dense dusty plasmas with high fugacity

    NASA Astrophysics Data System (ADS)

    Rao, N. N.

    2000-03-01

    A detailed investigation of electrostatic dust wave modes in unmagnetized dusty plasmas consisting of electrons, ions and dust grains has been carried out over a wide range of dust fugacity and wave frequency by using fluid as well as kinetic (Vlasov) theories. The dust fugacity parameter is defined by f≡4πnd0λD2R˜ND R/λD where nd0, λD and R are respectively the dust number density, the plasma Debye length and the grain size (radius), and ND=4πnd0λD3/3 is the dust plasma parameter. Dusty plasmas are considered to be tenuous, dilute or dense according as f≪1, ˜1, or ≫1. In particular, attention is focused on the "dust-acoustic waves" (DAWs) and the "dust-Coulomb waves" (DCWs) which exist in the tenuous (low fugacity) and the dense (high fugacity) regimes, respectively, when the wave frequency is much smaller than the grain charging frequency. Unlike the DAWs, which exist even with constant grain charge, the DCWs [N. N. Rao, Phys. Plasmas 6, 4414 (1999)] are the normal modes associated with grain charge fluctuations, and exist in dense dusty plasmas. In the long wavelength limit, the DCW phase speed scales as ˜CDA/√f where CDA is the DAW phase speed. In the dilute (medium fugacity) regime, the two modes merge into a single mode, which may be called the "dust charge-density wave" (DCDW) since the latter involves contributions arising from both the DAW and the DCW. On the other hand, for frequencies much larger than the charging frequency, DAWs are shown to exist also in the dilute regime. The real frequency as well as the damping rate in each case are explicitly calculated from both the fluid as well the kinetic theories, and a comparison between the two has been carried out. In the allowed fugacity regimes (tenuous, dilute or dense), all the three waves are weakly damped and, hence, can propagate as normal modes. The present analysis of wave propagation in dusty plasmas over different fugacity regimes suggests the introduction of a new length scale

  13. A first principles calculation of the oxygen uptake in the human pulmonary acinus at maximal exercise.

    PubMed

    Foucquier, A; Filoche, M; Moreira, A A; Andrade, J S; Arbia, G; Sapoval, B

    2013-02-01

    It has recently been shown that the acinus can have a reduced efficiency due to a "screening effect" governed by the ratio of oxygen diffusivity to membrane permeability, the gas flow velocity, as well as the size and configuration of the acinus. We present here a top to bottom calculation of the functioning of a machine acinus at exercise that takes this screening effect into account. It shows that, given the geometry and the breathing dynamics of real acini, respiration can be correlated to a single equivalent parameter that we call the integrative permeability. In particular we find that both V(O(2,max)) and PA(O(2)) depend on this permeability in a non-linear manner. Numerical solutions of dynamic convection-diffusion equations indicate that only a narrow range of permeability values is compatible with the experimental measurements of PA(O(2)) and V(O(2,max)). These permeability values are significantly smaller than those found in the literature. In a second step, we present a new type of evaluation of the diffusive permeability, yielding values compatible with the top to bottom approach, but smaller than the usual morphometric value.

  14. A Nomogram for Calculation of Oxygen Consumption from Minute Ventilation at Varying Workloads

    DTIC Science & Technology

    1979-07-01

    981~ IZ:;: I~ ~ TATL’MLNrh j.V Approved for public releasel ’ý [ I .Ad& - ABSTRACT .L Oxygen consumption can be difficult and time consuming to measure ...employed to evaluate diff-erent aspects of cardiopulmonary function (1). One of the principal measurements used to quantify response to exercise is...the oxygen consumption. The direct measurement of oxygen consumption is time consuming and cumbersome. Unfortunately, no reliable indirect method for

  15. K-alpha X-rays from cosmic ray oxygen. [Detection and calculation of equilibrium charge fractions

    NASA Technical Reports Server (NTRS)

    Pravdo, S. H.; Boldt, E. A.

    1975-01-01

    Equilibrium charge fractions are calculated for subrelativistic cosmic ray oxygen ions in the interstellar medium. These are used to determine the expected flux of K-alpha rays arising from atomic processes for a number of different postulated interstellar oxygen spectra. Relating these results to the diffuse X-ray background measured at the appropriate energy level suggests an observable line feature. If the flux of low energy cosmic ray oxygen is sufficiently large, K-alpha X-ray line emission from these nuclei will comprise a significant fraction of the total diffuse flux at approximately 0.6 keV. A satellite borne detector with a resolution greater than 30 percent could observe this feature if the subrelativistic interstellar cosmic ray oxygen spectrum is as large as certain theoretical estimates expressed in the text.

  16. Calculated values of atomic oxygen fluences and solar exposure on selected surfaces of LDEF

    NASA Technical Reports Server (NTRS)

    Gillis, J. R.; Pippin, H. G.; Bourassa, R. J.; Gruenbaum, P. E.

    1995-01-01

    Atomic oxygen (AO) fluences and solar exposure have been modeled for selected hardware from the Long Duration Exposure Facility (LDEF). The atomic oxygen exposure was modeled using the microenvironment modeling code SHADOWV2. The solar exposure was modeled using the microenvironment modeling code SOLSHAD version 1.0.

  17. RELATIVISTIC CALCULATION OF TRANSITION PROBABILITIES FOR 557.7 nm AND 297.2 nm EMISSION LINES IN OXYGEN

    SciTech Connect

    Chantler, C. T.; Nguyen, T. V. B.; Lowe, J. A.; Grant, I. P.

    2013-05-20

    The 557.7 nm green line and the 297.2 nm ultraviolet line in oxygen have been studied extensively due to their importance in astrophysics and atmospheric science. Despite the enormous effort devoted to these two prominent transition lines over 30 years, and in fact going back to 1934, the ratio of their transition probabilities remains a subject of major discrepancies amongst various theoretical calculations for many decades. Moreover, theoretical results are inconsistent with available laboratory results, as well as recent spacecraft measurements of Earth's airglow. This work presents new relativistic theoretical calculations of the transition probabilities of these two photoemission lines from neutral oxygen using the multi-configuration Dirac-Hartree-Fock method. Our calculations were performed in both length and velocity gauges in order to check for accuracy and consistency, with agreement to 8%. Whilst remaining a challenging computation, these results directly bear upon interpretations of plasma processes and ionization regimes in the universe.

  18. Quantum mechanical calculations suggest that lytic polysaccharide monooxygenases use a copper-oxyl, oxygen-rebound mechanism.

    PubMed

    Kim, Seonah; Ståhlberg, Jerry; Sandgren, Mats; Paton, Robert S; Beckham, Gregg T

    2014-01-07

    Lytic polysaccharide monooxygenases (LPMOs) exhibit a mononuclear copper-containing active site and use dioxygen and a reducing agent to oxidatively cleave glycosidic linkages in polysaccharides. LPMOs represent a unique paradigm in carbohydrate turnover and exhibit synergy with hydrolytic enzymes in biomass depolymerization. To date, several features of copper binding to LPMOs have been elucidated, but the identity of the reactive oxygen species and the key steps in the oxidative mechanism have not been elucidated. Here, density functional theory calculations are used with an enzyme active site model to identify the reactive oxygen species and compare two hypothesized reaction pathways in LPMOs for hydrogen abstraction and polysaccharide hydroxylation; namely, a mechanism that employs a η(1)-superoxo intermediate, which abstracts a substrate hydrogen and a hydroperoxo species is responsible for substrate hydroxylation, and a mechanism wherein a copper-oxyl radical abstracts a hydrogen and subsequently hydroxylates the substrate via an oxygen-rebound mechanism. The results predict that oxygen binds end-on (η(1)) to copper, and that a copper-oxyl-mediated, oxygen-rebound mechanism is energetically preferred. The N-terminal histidine methylation is also examined, which is thought to modify the structure and reactivity of the enzyme. Density functional theory calculations suggest that this posttranslational modification has only a minor effect on the LPMO active site structure or reactivity for the examined steps. Overall, this study suggests the steps in the LPMO mechanism for oxidative cleavage of glycosidic bonds.

  19. Quantum mechanical calculations suggest that lytic polysaccharide monooxygenases use a copper-oxyl, oxygen-rebound mechanism

    PubMed Central

    Kim, Seonah; Ståhlberg, Jerry; Sandgren, Mats; Paton, Robert S.; Beckham, Gregg T.

    2014-01-01

    Lytic polysaccharide monooxygenases (LPMOs) exhibit a mononuclear copper-containing active site and use dioxygen and a reducing agent to oxidatively cleave glycosidic linkages in polysaccharides. LPMOs represent a unique paradigm in carbohydrate turnover and exhibit synergy with hydrolytic enzymes in biomass depolymerization. To date, several features of copper binding to LPMOs have been elucidated, but the identity of the reactive oxygen species and the key steps in the oxidative mechanism have not been elucidated. Here, density functional theory calculations are used with an enzyme active site model to identify the reactive oxygen species and compare two hypothesized reaction pathways in LPMOs for hydrogen abstraction and polysaccharide hydroxylation; namely, a mechanism that employs a η1-superoxo intermediate, which abstracts a substrate hydrogen and a hydroperoxo species is responsible for substrate hydroxylation, and a mechanism wherein a copper-oxyl radical abstracts a hydrogen and subsequently hydroxylates the substrate via an oxygen-rebound mechanism. The results predict that oxygen binds end-on (η1) to copper, and that a copper-oxyl–mediated, oxygen-rebound mechanism is energetically preferred. The N-terminal histidine methylation is also examined, which is thought to modify the structure and reactivity of the enzyme. Density functional theory calculations suggest that this posttranslational modification has only a minor effect on the LPMO active site structure or reactivity for the examined steps. Overall, this study suggests the steps in the LPMO mechanism for oxidative cleavage of glycosidic bonds. PMID:24344312

  20. Fe-Ni exchange between olivine and sulphide liquid: implications for oxygen barometry in sulphide-saturated magmas

    NASA Astrophysics Data System (ADS)

    Brenan, J. M.; Caciagli, N. C.

    2000-01-01

    In order to better understand the behaviour of nickel in magmatic processes, we have measured the apparent equilibrium constant ( KD) for the exchange of Fe and Ni between coexisting olivine and sulphide liquid at controlled oxygen and sulphur fugacities ( fO 2 = 10 -8-10 -10 and fS 2 = 10 -2-10 -4) over the temperature range 1200 to 1400°C and with 5 to 50 wt.% nickel in the sulphide liquid. Measured values of KD are independent of temperature and sulphur fugacity, but increase linearly with the nickel content of the sulphide liquid, and follow a power-law increase with oxygen fugacity; behaviour that is consistent with previous measurements of KD under controlled conditions of fO 2 and fS 2. The variation of KD with melt nickel content and fO 2 is most likely the result of nonideal mixing in the sulphide liquid, which results in a decrease in γ NiS/γ FeS with melt metal/sulphur ratio. As a consequence of the systematic dependence of KD on fO 2, a new oxygen barometer is proposed for estimating oxygen fugacity in igneous rocks that were cosaturated in olivine and sulphide liquid. Application of the experimental results to natural samples shows that the relatively large variations that exist in KD values from different olivine + sulphide-saturated rock suites can be interpreted as arising from variations in fO 2 and/or the nickel content of the sulphide liquid. Oxygen fugacities calculated for oceanic basalt samples using the proposed Fe-Ni exchange oxybarometer are found to be relatively high (10 -8.5-10 -10.4) which is in accord with the range of values determined using glass ferric/ferrous ratios. Moreover, the very low fO 2 (˜10 -14) calculated for the mafic dike from Disko Island is consistent with the presence of native iron in these samples and is in quantitative agreement with indicators of fO 2 based on chromite- and olivine-melt partitioning of vanadium. Consideration of the fO 2 exhibited by olivine + sulphide-saturated intrusive suites reveals a

  1. Hydrothermal hydration of Martian crust: illustration via geochemical model calculations.

    PubMed

    Griffith, L L; Shock, E L

    1997-04-25

    If hydrothermal Systems existed on Mars, hydration of crustal rocks may have had the potential to affect the water budget of the planet. We have conducted geochemical model calculations to investigate the relative roles of host rock composition, temperature, water-to-rock ratio, and initial fluid oxygen fugacity on the mineralogy of hydrothermal alteration assemblages, as well as the effectiveness of alteration to store water in the crust as hydrous minerals. In order to place calculations for Mars in perspective, models of hydrothermal alteration of three genetically related Icelandic volcanics (a basalt, andesite, and rhyolite) are presented, together with results for compositions based on SNC meteorite samples (Shergotty and Chassigny). Temperatures from 150 degrees C to 250 degrees C, water-to-rock ratios from 0.1 to 1000, and two initial fluid oxygen fugacities are considered in the models. Model results for water-to-rock ratios less than 10 are emphasized because they are likely to be more applicable to Mars. In accord with studies of low-grade alteration of terrestrial rocks, we find that the major controls on hydrous mineral production are host rock composition and temperature. Over the range of conditions considered, the alteration of Shergotty shows the greatest potential for storing water as hydrous minerals, and the alteration of Icelandic rhyolite has the lowest potential.

  2. Hydrothermal hydration of Martian crust: illustration via geochemical model calculations

    NASA Technical Reports Server (NTRS)

    Griffith, L. L.; Shock, E. L.

    1997-01-01

    If hydrothermal Systems existed on Mars, hydration of crustal rocks may have had the potential to affect the water budget of the planet. We have conducted geochemical model calculations to investigate the relative roles of host rock composition, temperature, water-to-rock ratio, and initial fluid oxygen fugacity on the mineralogy of hydrothermal alteration assemblages, as well as the effectiveness of alteration to store water in the crust as hydrous minerals. In order to place calculations for Mars in perspective, models of hydrothermal alteration of three genetically related Icelandic volcanics (a basalt, andesite, and rhyolite) are presented, together with results for compositions based on SNC meteorite samples (Shergotty and Chassigny). Temperatures from 150 degrees C to 250 degrees C, water-to-rock ratios from 0.1 to 1000, and two initial fluid oxygen fugacities are considered in the models. Model results for water-to-rock ratios less than 10 are emphasized because they are likely to be more applicable to Mars. In accord with studies of low-grade alteration of terrestrial rocks, we find that the major controls on hydrous mineral production are host rock composition and temperature. Over the range of conditions considered, the alteration of Shergotty shows the greatest potential for storing water as hydrous minerals, and the alteration of Icelandic rhyolite has the lowest potential.

  3. Effects of oxygen vacancy on 3d transition-metal doped anatase TiO2: First principles calculations

    NASA Astrophysics Data System (ADS)

    Zhao, Ya Fei; Li, Can; Lu, Song; Yan, Li Jin; Gong, Yin Yan; Niu, Leng Yuan; Liu, Xin Juan

    2016-03-01

    In this work, systematic study of the formation energy, crystalline and electronic structures of 3d transition metal (Sc, V, Cr, Mn, Fe, Co and Ni) doped anatase TiO2 specimens with and without oxygen vacancy has been carried out by the first principles calculations. The impurity states located at the band gaps enhance the visible light absorption, and the oxygen vacancy result in the EF move into the CB for some doped systems, which induce the Ti3+ ions and promote the separation of photogenerated carriers. Doping and oxygen vacancy can change the hybrid strength and MP value of TMsbnd O bonding which has the approximately linearly with the band gap.

  4. Effect of oxygen vacancies on the electronic and optical properties of tungsten oxide from first principles calculations

    NASA Astrophysics Data System (ADS)

    Mehmood, Faisal; Pachter, Ruth; Murphy, Neil R.; Johnson, Walter E.; Ramana, Chintalapalle V.

    2016-12-01

    In this work, we investigated theoretically the role of oxygen vacancies on the electronic and optical properties of cubic, γ-monoclinic, and tetragonal phases of tungsten oxide (WO3) thin films. Following the examination of structural properties and stability of the bulk tungsten oxide polymorphs, we analyzed band structures and optical properties, applying density functional theory (DFT) and GW (Green's (G) function approximation with screened Coulomb interaction (W)) methods. Careful benchmarking of calculated band gaps demonstrated the importance of using a range-separated functional, where results for the pristine room temperature γ-monoclinic structure indicated agreement with experiment. Further, modulation of the band gap for WO3 structures with oxygen vacancies was quantified. Dielectric functions for cubic WO3, calculated at both the single-particle, essentially time-dependent DFT, as well as many-body GW-Bethe-Salpeter equation levels, indicated agreement with experimental data for pristine WO3. Interestingly, we found that introducing oxygen vacancies caused appearance of lower energy absorptions. A smaller refractive index was indicated in the defective WO3 structures. These predictions could lead to further experiments aimed at tuning the optical properties of WO3 by introducing oxygen vacancies, particularly for the lower energy spectral region.

  5. Singlet oxygen generation in PUVA therapy studied using electronic structure calculations

    NASA Astrophysics Data System (ADS)

    Serrano-Pérez, Juan José; Olaso-González, Gloria; Merchán, Manuela; Serrano-Andrés, Luis

    2009-06-01

    The ability of furocoumarins to participate in the PUVA (Psoralen + UV-A) therapy against skin disorders and some types of cancer, is analyzed on quantum chemical grounds. The efficiency of the process relies on its capability to populate its lowest triplet excited state, and then either form adducts with thymine which interfere DNA replication or transfer its energy, generating singlet molecular oxygen damaging the cell membrane in photoactivated tissues. By determining the spin-orbit couplings, shown to be the key property, in the intersystem crossing yielding the triplet state of the furocoumarin, the electronic couplings in the triplet-triplet energy transfer process producing the singlet oxygen, and the reaction rates and lifetimes, the efficiency in the phototherapeutic action of the furocoumarin family is predicted as: khellin < 5-methoxypsoralen (5-MOP) < 8-methoxypsoralen (8-MOP) < psoralen < 4,5‧,8-trimethylpsoralen (TMP) < 3-carbethoxypsoralen (3-CPS), the latter being the most efficient photosensitizer and singlet oxygen generator.

  6. Monte Carlo method for calculating oxygen abundances and their uncertainties from strong-line flux measurements

    NASA Astrophysics Data System (ADS)

    Bianco, F. B.; Modjaz, M.; Oh, S. M.; Fierroz, D.; Liu, Y. Q.; Kewley, L.; Graur, O.

    2016-07-01

    We present the open-source Python code pyMCZ that determines oxygen abundance and its distribution from strong emission lines in the standard metallicity calibrators, based on the original IDL code of Kewley and Dopita (2002) with updates from Kewley and Ellison (2008), and expanded to include more recently developed calibrators. The standard strong-line diagnostics have been used to estimate the oxygen abundance in the interstellar medium through various emission line ratios (referred to as indicators) in many areas of astrophysics, including galaxy evolution and supernova host galaxy studies. We introduce a Python implementation of these methods that, through Monte Carlo sampling, better characterizes the statistical oxygen abundance confidence region including the effect due to the propagation of observational uncertainties. These uncertainties are likely to dominate the error budget in the case of distant galaxies, hosts of cosmic explosions. Given line flux measurements and their uncertainties, our code produces synthetic distributions for the oxygen abundance in up to 15 metallicity calibrators simultaneously, as well as for E(B- V) , and estimates their median values and their 68% confidence regions. We provide the option of outputting the full Monte Carlo distributions, and their Kernel Density estimates. We test our code on emission line measurements from a sample of nearby supernova host galaxies (z < 0.15) and compare our metallicity results with those from previous methods. We show that our metallicity estimates are consistent with previous methods but yield smaller statistical uncertainties. It should be noted that systematic uncertainties are not taken into account. We also offer visualization tools to assess the spread of the oxygen abundance in the different calibrators, as well as the shape of the estimated oxygen abundance distribution in each calibrator, and develop robust metrics for determining the appropriate Monte Carlo sample size. The code

  7. A Graphical Representation for the Fugacity of a Pure Substance

    ERIC Educational Resources Information Center

    Book, Neil L.; Sitton, Oliver C.

    2010-01-01

    The thermodynamic equations used to define and compute the fugacity of a pure substance are depicted as processes on a semi-logarithmic plot of pressure vs. molar Gibbs energy (PG diagram) with isotherms for the substance behaving as an ideal gas superimposed. The PG diagram clearly demonstrates the physical basis for the definitions and the…

  8. Oxygen vacancy diffusion in bulk SrTiO3 from density functional theory calculations

    DOE PAGES

    Zhang, Lipeng; Liu, Bin; Zhuang, Houlong; ...

    2016-04-01

    Point defects and point defect diffusion contribute significantly to the properties of perovskite materials. However, even for the prototypical case of oxygen vacancies in SrTiO3 (STO), predictions vary widely. Here we present a comprehensive and systematic study of the diffusion barriers for this material. We use density functional theory (DFT) and assess the role of different cell sizes, density functionals, and charge states. Our results show that vacancy-induced octahedral rotations, which are limited by the boundary conditions of the supercell, can significantly affect the computed oxygen vacancy diffusion energy barrier. The diffusion energy barrier of a charged oxygen vacancy ismore » lower than that of a neutral one. Unexpectedly, we find that with increasing supercell size, the effects of the oxygen vacancy charge state, the type of DFT exchange and correlation functional on the energy barrier diminish, and the different DFT predictions asymptote to a value in the range of 0.39-0.49 eV. This work provides important insight and guidance that should be considered for investigations of point defect diffusion in other perovskite materials and in oxide superlattices.« less

  9. Oxygen vacancy diffusion in bulk SrTiO3 from density functional theory calculations

    SciTech Connect

    Zhang, Lipeng; Liu, Bin; Zhuang, Houlong; Kent, Paul R. C.; Cooper, Valentino R.; Ganesh, Panchapakesan; Xu, Haixuan

    2016-04-01

    Point defects and point defect diffusion contribute significantly to the properties of perovskite materials. However, even for the prototypical case of oxygen vacancies in SrTiO3 (STO), predictions vary widely. Here we present a comprehensive and systematic study of the diffusion barriers for this material. We use density functional theory (DFT) and assess the role of different cell sizes, density functionals, and charge states. Our results show that vacancy-induced octahedral rotations, which are limited by the boundary conditions of the supercell, can significantly affect the computed oxygen vacancy diffusion energy barrier. The diffusion energy barrier of a charged oxygen vacancy is lower than that of a neutral one. Unexpectedly, we find that with increasing supercell size, the effects of the oxygen vacancy charge state, the type of DFT exchange and correlation functional on the energy barrier diminish, and the different DFT predictions asymptote to a value in the range of 0.39-0.49 eV. This work provides important insight and guidance that should be considered for investigations of point defect diffusion in other perovskite materials and in oxide superlattices.

  10. First-principles calculations of the diffusion of atomic oxygen in nickel: thermal expansion contribution.

    PubMed

    Megchiche, E H; Amarouche, M; Mijoule, C

    2007-07-25

    Within the framework of density functional theory using the projector augmented-wave (PAW) method, we present some energetic properties of atomic oxygen interstitials in crystalline Ni, i.e. the insertion and activation energies of the O diffusion. Concerning the activation energy, two pathways for the migration process are studied. The charge transfer process between atomic oxygen and nickel atoms is analysed in the interstitial sites. We find that the interstitial octahedral site (O site) is lower in energy than the tetrahedral site (T site). The most favourable pathway for the migration between two octahedral sites corresponds to an intermediate metastable state located in a tetrahedral site. Concerning the charge transfers we find that the atomic oxygen ionizes as O(-) and that the electron migrates essentially from the Ni nearest neighbours of atomic oxygen. In addition, the thermal expansion contribution through the dilatation of the solid is studied. When the thermal expansion is introduced, we show that the insertion process is stabilized and that the tetrahedral insertion energy becomes nearly equal to the octahedral ones. However, the activation energy decreases with the dilatation. Taking into account the thermal expansion effects, our results are consistent with the more reliable experimental data.

  11. Computation of decompression schedules for single inert gas-oxygen dives using a hand-held programmable calculator.

    PubMed

    Ranade, A; Peterson, R E

    1980-08-01

    An algorithm for on-site computation with a hand-held programmable calculator (TI-59, Texas Instruments) of single inert-gas decompression schedules is described. This program is based on Workman's 'M-value' method. It can compute decompression schedules with changes in the oxygen content of the breathing mixture and extension of stay at any decompression stop. The features of the program that enable calculation of atypical dive profiles, along with the portability of small calculators, would make such an algorithm suitable for on-site applications. However, since dive profiles generated by the program have not yet been tested, divers are warned not to generate schedules until their safety has been established by field tests.

  12. Ab-initio calculation study on the formation mechanism of boron-oxygen complexes in c-Si

    SciTech Connect

    Yu, Xuegong; Chen, Peng; Chen, Xianzi; Liu, Yong; Yang, Deren

    2015-07-15

    Boron-oxygen (B-O) complex in crystalline silicon (c-Si) solar cells is responsible for the light-induced efficiency degradation of solar cell. However, the formation mechanism of B-O complex is not clear yet. By Ab-initio calculation, it is found that the stagger-type oxygen dimer (O{sub 2i}{sup st}) should be the component of B-O complex, whose movement occurs through its structure reconfiguration at low temperature, instead of its long-distance diffusion. The O{sub 2i}{sup st} can form two stable “latent centers” with the B{sub s}, which are recombination-inactive. The latent centers can be evolved into the metastable recombination centers via their structure transformation in the presence of excess carriers. These results can well explain the formation behaviors of B-O complexes in c-Si.

  13. Strain-induced phase and oxygen-vacancy stability in ionic interfaces from first-principles calculations

    SciTech Connect

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

    2014-12-03

    Understanding interfacial chemistry is becoming crucial in materials design for heterointerfaces. Using density functional theory, we elucidate the effect of strained interfaces on phase and oxygen-vacancy stability for CeO2 | ZrO2, ThO2 | ZrO2 and CeO2 | ThO2 interfaces. The calculations show that ZrO2 transforms from cubic fluorite to the orthorhombic columbite under tensile strain providing evidence of a previous experimental speculation of an unrecognized ZrO2 phase. We also show that oxygen vacancies could be preferably stabilized on either side of the interface by manipulating strain. We predict that they are stable in tensile-strain, and unstable in compressivestrained materials.

  14. Iron-oxygen vacancy defect centers in PbTi O3 : Newman superposition model analysis and density functional calculations

    NASA Astrophysics Data System (ADS)

    Meštrić, H.; Eichel, R.-A.; Kloss, T.; Dinse, K.-P.; Laubach, So.; Laubach, St.; Schmidt, P. C.; Schönau, K. A.; Knapp, M.; Ehrenberg, H.

    2005-04-01

    The Fe3+ center in ferroelectric PbTiO3 together with an oxygen vacancy forms a charged defect associate, oriented along the crystallographic c axis. Its microscopic structure has been analyzed in detail comparing results from a semiempirical Newman superposition model analysis based on fine-structure data and from calculations using density functional theory. Both methods give evidence for a substitution of Fe3+ for Ti4+ as an acceptor center. The position of the iron ion in the ferroelectric phase is found to be similar to the B site in the paraelectric phase. Partial charge compensation is locally provided by a directly coordinated oxygen vacancy. Using high-resolution synchrotron powder diffraction, it was verified that lead titanate remains tetragonal down to 12K , exhibiting a c/a ratio of 1.0721.

  15. Comparison of Oxygen Gauche Effects in Poly(Oxyethylene) and Poly(ethylene terephtylene) Based on Quantum Chemistry Calculations

    NASA Technical Reports Server (NTRS)

    Jaffe, Richard; Han, Jie; Yoon, Do; Langhoff, Stephen R. (Technical Monitor)

    1997-01-01

    The so-called oxygen gauche effect in poly(oxyethylene) (POE) and its model molecules such as 1,2-dimethoxyethane (DME) and diglyme (CH3OC2H4OC2H4OCH3) is manifested in the preference for gauche C-C bond conformations over trans. This has also been observed for poly(ethylene terephthalate) (PET). Our previous quantum chemistry calculations demonstrated that the large C-C gauche population in DME is due, in part, to a low-lying tg +/- g+ conformer that exhibits a substantial 1,5 CH ... O attraction. New calculations will be described that demonstrate the accuracy of the original quantum chemistry calculations. In addition, an extension of this work to model molecules for PET will be presented. It is seen that the C-C gauche preference is much stronger in 1,2 diacetoxyethane than in DME. In addition, there exist low-lying tg +/- g+/- and g+/-g+/-g+/- conformers that exhibit 1,5 CH ... O attractions involving the carbonyl oxygens. It is expected that the -O-C-C-O- torsional properties will be quite different in these two polymers. The quantum chemistry results are used to parameterize rotational isomeric states models (RIS) and force fields for molecular dynamics simulations of these polymers.

  16. Calculation of singlet oxygen formation from one photon absorbing photosensitizers used in PDT

    NASA Astrophysics Data System (ADS)

    Potasek, M.; Parilov, Evgueni; Beeson, K.

    2013-03-01

    Advances in biophotonic medicine require new information on photodynamic mechanisms. In photodynamic therapy (PDT), a photosensitizer (PS) is injected into the body and accumulates at higher concentrations in diseased tissue compared to normal tissue. The PS absorbs light from a light source and generates excited-state triplet states of the PS. The excited triplet states of the PS can then react with ground state molecular oxygen to form excited singlet - state oxygen or form other highly reactive species. The reactive species react with living cells, resulting in cel l death. This treatment is used in many forms of cancer including those in the prostrate, head and neck, lungs, bladder, esophagus and certain skin cancers. We developed a novel numerical method to model the photophysical and photochemical processes in the PS and the subsequent energy transfer to O2, improving the understanding of these processes at a molecular level. Our numerical method simulates light propagation and photo-physics in PS using methods that build on techniques previously developed for optical communications and nonlinear optics applications.

  17. Thermal desorption of molecular oxygen from SnO2 (110) surface: Insights from first-principles calculations

    NASA Astrophysics Data System (ADS)

    Golovanov, Viacheslav; Golovanova, Viktoria; Rantala, Tapio T.

    2016-02-01

    First-principles density functional theory calculations in the generalized gradient approximation, with plane wave basis set and pseudopotentials, have been used to investigate the desorption pathways of molecular oxygen species adsorbed on the SnO2 (110) surface. Energetics of the thermodynamically favored precursors is studied in dependence on the surface charge provided either by surface defects or by donor type impurities from the near-surface region. The resonant desorption modes of O2 molecules are examined in the framework of ab initio atomic thermodynamics and relationship of these results to experimental observations is discussed.

  18. Calculations of oxygen transport by red blood cells and hemoglobin solutions in capillaries.

    PubMed

    Vadapalli, Arjun; Goldman, Daniel; Popel, Aleksander S

    2002-05-01

    A theoretical model is developed to investigate the influence of hemoglobin-based oxygen carriers (HBOCs) on oxygen transport in capillary-size vessels. A discrete cell model is presented with red blood cells (RBCs) represented in their realistic parachute shape flowing in a single file through a capillary. The model includes the free and Hb-facilitated transport of O2 and Hb-O2 kinetics in the RBC and plasma, diffusion of free O2 in the suspending phase, capillary wall, interstitium and tissue. A constant tissue consumption rate is specified that drives the simultaneous release of O2 from RBC and plasma as the cells traverse the capillary. The model mainly focuses on low capillary hematocrits and studies the effect of free hemoglobin affinity, cooperativity and concentration. The results are expressed in the form of cell and capillary mass transfer coefficients, or inverse transport resistances, that relate the spatially averaged flux of O2 coming out of the RBC and capillary to a driving force for O2 diffusion. The results show that HBOCs at a concentration of 7 g/dl reduce the intracapillary transport resistance by as much as 60% when capillary hematocrit is 0.2. HBOCs with high O2 affinity unload most O2 at the venular end, while those with low affinity supply O2 at the arteriolar end. A higher cooperativity did not favor O2 delivery due to the large variation in the mass transfer coefficient values during O2 unloading. The mass transfer coefficients obtained will be used in simulations of O2 transport in complex capillary networks.

  19. A fugacity-based indoor residential pesticide fate model

    SciTech Connect

    Bennett, Deborah H.; Furtaw, Edward J.; McKone, Thomas E.

    2002-06-01

    Dermal and non-dietary pathways are potentially significant exposure pathways to pesticides used in residences. Exposure pathways include dermal contact with residues on surfaces, ingestion from hand- and object-to-mouth activities, and absorption of pesticides into food. A limited amount of data has been collected on pesticide concentrations in various residential compartments following an application. But models are needed to interpret this data and make predictions about other pesticides based on chemical properties. In this paper, we propose a mass-balance compartment model based on fugacity principles. We include air (both gas phase and aerosols), carpet, smooth flooring, and walls as model compartments. Pesticide concentrations on furniture and toys, and in food, are being added to the model as data becomes available. We determine the compartmental fugacity capacity and mass transfer-rate coefficient for wallboard as an example. We also present the framework and equations needed for a dynamic mass-balance model.

  20. Ocean Surface Carbon Dioxide Fugacity Observed from Space

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Xie, Xiaosu

    2014-01-01

    We have developed and validated a statistical model to estimate the fugacity (or partial pressure) of carbon dioxide (CO2) at sea surface (pCO2sea) from space-based observations of sea surface temperature (SST), chlorophyll, and salinity. More than a quarter million in situ measurements coincident with satellite data were compiled to train and validate the model. We have produced and made accessible 9 years (2002-2010) of the pCO2sea at 0.5 degree resolutions daily over the global ocean. The results help to identify uncertainties in current JPL Carbon Monitoring System (CMS) model-based and bottom-up estimates over the ocean. The utility of the data to reveal multi-year and regional variability of the fugacity in relation to prevalent oceanic parameters is demonstrated.

  1. Electrical conductivity in oxygen-deficient phases of transition metal oxides from first-principles calculations.

    SciTech Connect

    Bondi, Robert James; Desjarlais, Michael Paul; Thompson, Aidan Patrick; Brennecka, Geoffrey L.; Marinella, Matthew

    2013-09-01

    Density-functional theory calculations, ab-initio molecular dynamics, and the Kubo-Greenwood formula are applied to predict electrical conductivity in Ta2Ox (0 x 5) as a function of composition, phase, and temperature, where additional focus is given to various oxidation states of the O monovacancy (VOn; n=0,1+,2+). Our calculations of DC conductivity at 300K agree well with experimental measurements taken on Ta2Ox thin films and bulk Ta2O5 powder-sintered pellets, although simulation accuracy can be improved for the most insulating, stoichiometric compositions. Our conductivity calculations and further interrogation of the O-deficient Ta2O5 electronic structure provide further theoretical basis to substantiate VO0 as a donor dopant in Ta2O5 and other metal oxides. Furthermore, this dopant-like behavior appears specific to neutral VO cases in both Ta2O5 and TiO2 and was not observed in other oxidation states. This suggests that reduction and oxidation reactions may effectively act as donor activation and deactivation mechanisms, respectively, for VO0 in transition metal oxides.

  2. The Effect of Sulfur Fugacity on Pt, Pd and Au in Magmatic-Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Bell, A.; Simon, A.

    2009-05-01

    We have constrained experimentally the effect of sulfur fugacity (fS2) and sulfide saturation on the fractionation and partitioning behavior of Pt, Pd and Au in a felsic silicate melt + sulfide crystal/melt + oxide + supercritical aqueous fluid phase + Pt + Pd + Au system. Experiments were performed at 800°C, 150 MPa, with oxygen fugacity (fO2) fixed at approximately the nickel + nickel oxide buffer (NNO). Sulfur fugacity in the experiments was varied five orders of magnitude from approximately logfS2 = 0 to logfS2 = -5 by using two different sulfide phase assemblages. Sulfide assemblage one consisted initially of chalcopyrite plus pyrrhotite and assemblage two consisted of chalcopyrite plus bornite. At run conditions, in both assemblages, pyrrhotite transformed compositionally to monosulfide solid solution (mss), chalcopyrite to intermediate solid solution (Iss), and in assemblage two chalcopyrite and bornite formed a sulfide melt. Run- product silicate glass (i.e., quenched silicate melt) and crystalline materials were analyzed by using both electron probe microanalysis (EPMA) for major elements and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for major and trace elements. The measured concentrations of Pt, Pd, and Au in quenched silicate melt in runs with logfS2 values ranging from approximately 0 to -5, do not exhibit any apparent dependence on the dissolved sulfur content of the melt. The measured Pt, Pd and Au concentrations in mss vary as a function of fS2. The measured Pt, Pd and Au concentrations in Iss do not appear to be dependent on fS2. The system variables fS2 and fO2, working in concert with each other, control the stable magmatic sulfide phase assemblage. Additionally, the system fS2 strongly influences the solubility of Pt, Pd, and Au as lattice bound components in some common crystalline magmatic sulfide phases. Both the stable magmatic sulfide phase assemblage and the solubility of Pt, Pd, and Au as constituents in

  3. Bedside determination of bicarbonate and base excess, blood oxygen saturation and content, VD/VT, and P50 using a programmable calculator.

    PubMed

    Wilkinson, P L

    1979-06-01

    Assessing and modifying oxygen transport are major parts of ICU patient management. Determination of base excess, blood oxygen saturation and content, dead space ventilation, and P50 helps in this management. A program is described for determining these variables using a T1 59 programmable calculator and PC 100A printer. Each variable can be independently calculated without running the whole program. The calculator-printer's small size, low cost, and hard copy printout make it a valuable and versatile tool for calculating physiological variables. The program is easily entered by an stored on magnetic card, and prompts the user to enter the appropriate variables, making is easy to run by untrained personnel.

  4. Investigation of oxygen self-diffusion in PuO2 by combining molecular dynamics with thermodynamic calculations

    SciTech Connect

    Saltas, V.; Chroneos, A.; Cooper, Michael William D.; Fitzpatrick, M. E.; Vallianatos, F.

    2016-01-01

    In the present work, the defect properties of oxygen self-diffusion in PuO2 are investigated over a wide temperature (300–1900 K) and pressure (0–10 GPa) range, by combining molecular dynamics simulations and thermodynamic calculations. Based on the well-established cBΩ thermodynamic model which connects the activation Gibbs free energy of diffusion with the bulk elastic and expansion properties, various point defect parameters such as activation enthalpy, activation entropy, and activation volume were calculated as a function of T and P. Molecular dynamics calculations provided the necessary bulk properties for the proper implementation of the thermodynamic model, in the lack of any relevant experimental data. The estimated compressibility and the thermal expansion coefficient of activation volume are found to be more than one order of magnitude greater than the corresponding values of the bulk plutonia. As a result, the diffusion mechanism is discussed in the context of the temperature and pressure dependence of the activation volume.

  5. Investigation of oxygen self-diffusion in PuO2 by combining molecular dynamics with thermodynamic calculations

    DOE PAGES

    Saltas, V.; Chroneos, A.; Cooper, Michael William D.; ...

    2016-01-01

    In the present work, the defect properties of oxygen self-diffusion in PuO2 are investigated over a wide temperature (300–1900 K) and pressure (0–10 GPa) range, by combining molecular dynamics simulations and thermodynamic calculations. Based on the well-established cBΩ thermodynamic model which connects the activation Gibbs free energy of diffusion with the bulk elastic and expansion properties, various point defect parameters such as activation enthalpy, activation entropy, and activation volume were calculated as a function of T and P. Molecular dynamics calculations provided the necessary bulk properties for the proper implementation of the thermodynamic model, in the lack of any relevantmore » experimental data. The estimated compressibility and the thermal expansion coefficient of activation volume are found to be more than one order of magnitude greater than the corresponding values of the bulk plutonia. As a result, the diffusion mechanism is discussed in the context of the temperature and pressure dependence of the activation volume.« less

  6. Calculated volatilization rates of fuel oxygenate compounds and other gasoline-related compounds from rivers and streams

    USGS Publications Warehouse

    Pankow, J.F.; Rathbun, R.E.; Zogorski, J.S.

    1996-01-01

    Large amounts of the 'fuel-oxygenate' compound methyl-tert-butyl ether (MTBE) are currently being used in gasoline to reduce carbon monoxide and ozone in urban air and to boost fuel octane. Because MTBE can be transported to surface waters in various ways, established theory was used to calculate half-lives for MTBE volatilizing from flowing surface waters. Similar calculations were made for benzene as a representative of the 'BTEX' group of compounds (benzene, toluene, ethyl benzene, and the xylenes), and for tert-butyl alcohol (TBA). The calculations were made as a function of the mean flow velocity u (m/day), the mean flow depth h (m), the ambient temperature, and the wind speed. In deep, slow-moving flows, MTBE volatilizes at rates which are similar to those for the BTEX compounds. In shallow, fast-moving flows, MTBE volatilizes more slowly than benzene, though in such flows both MTBE and benzene volatilize quickly enough that these differences may often not have much practical significance. TBA was found to be essentially nonvolatile from water.

  7. Reply to Nicholson's comment on "Consistent calculation of aquatic gross production from oxygen triple isotope measurements" by Kaiser (2011)

    NASA Astrophysics Data System (ADS)

    Kaiser, J.; Abe, O.

    2012-08-01

    The comment by Nicholson (2011a) questions the "consistency" of the "definition" of the "biological end-member" used by Kaiser (2011a) in the calculation of oxygen gross production. "Biological end-member" refers to the relative oxygen isotope ratio difference between photosynthetic oxygen and Air-O2 (abbreviated 17δP and 18δP for 17O/16O and 18O/16O, respectively). The comment claims that this leads to an overestimate of the discrepancy between previous studies and that the resulting gross production rates are "30% too high". Nicholson recognises the improved accuracy of Kaiser's direct calculation ("dual-delta") method compared to previous approximate approaches based on 17O excess (17Δ) and its simplicity compared to previous iterative calculation methods. Although he correctly points out that differences in the normalised gross production rate (g) are largely due to different input parameters used in Kaiser's "base case" and previous studies, he does not acknowledge Kaiser's observation that iterative and dual-delta calculation methods give exactly the same g for the same input parameters (disregarding kinetic isotope fractionation during air-sea exchange). The comment is based on misunderstandings with respect to the "base case" 17δP and 18δP values. Since direct measurements of 17δP and 18δPdo not exist or have been lost, Kaiser constructed the "base case" in a way that was consistent and compatible with literature data. Nicholson showed that an alternative reconstruction of 17δP gives g values closer to previous studies. However, unlike Nicholson, we refrain from interpreting either reconstruction as a benchmark for the accuracy of g. A number of publications over the last 12 months have tried to establish which of these two reconstructions is more accurate. Nicholson draws on recently revised measurements of the relative 17O/16O difference between VSMOW and Air-O2 (17δVSMOW; Barkan and Luz, 2011), together with new measurements of photosynthetic

  8. Effective particle energies for stopping power calculation in radiotherapy treatment planning with protons and helium, carbon, and oxygen ions

    NASA Astrophysics Data System (ADS)

    Inaniwa, T.; Kanematsu, N.

    2016-10-01

    The stopping power ratio (SPR) of body tissues relative to water depends on the particle energy. For simplicity, however, most analytical dose planning systems do not account for SPR variation with particle energy along the beam’s path, but rather assume a constant energy for SPR estimation. The range error due to this simplification could be indispensable depending on the particle species and the assumed energy. This error can be minimized by assuming a suitable energy referred to as an ‘effective energy’ in SPR estimation. To date, however, the effective energy has never been investigated for realistic patient geometries. We investigated the effective energies for proton, helium-, carbon-, and oxygen-ion radiotherapy using volumetric models of the reference male and female phantoms provided by the International Commission on Radiological Protection (ICRP). The range errors were estimated by comparing the particle ranges calculated when particle energy variations were and were not considered. The effective energies per nucleon for protons and helium, carbon, and oxygen ions were 70 MeV, 70 MeV, 131 MeV, and 156 MeV, respectively. Using the determined effective energies, the range errors were reduced to  ⩽0.3 mm for respective particle species. For SPR estimation of multiple particle species, an effective energy of 100 MeV is recommended, with which the range error is  ⩽0.5 mm for all particle species.

  9. Comparative oxygen barometry in granulites, Bamble sector, SE Norway

    SciTech Connect

    Harlov, D.E. )

    1992-07-01

    Oxygen fugacities have been estimated for the high-grade portion of the Bamble granulite facies terrane, SE Norway, using both titaniferous magnetite-ilmenite and orthopyroxene-titaniferous magnetite-quartz oxygen barometers. The two oxygen barometers show good agreement, for samples indicating high titaniferous magnetite-ilmenite temperatures whereas agreement is poor for low-temperature samples. Oxygen fugacities estimated from titaniferous magnetite-ilmenite are considerably lower than those estimated from orthopyroxene-titaniferous magnetite-quartz. This discrepancy increases with a decrease in temperature, which appears to reflect preferential resetting of the hematite content in the ilmenite grains, without much alteration of the more numerous titaniferous magnetite or orthopyroxene grains. The mean temperature for non-reset samples, 795 {plus minus} 60C (1{sigma}), agrees well with temperatures obtained from garnet-orthopyroxene K{sub D} exchange thermometry in the same region, 785 {plus minus} 60C (1{sigma}). The non-reset oxygen fugacities also agree well with an independent study of the Bamble granulites by Cameron. The QUIlP equilibrium (Quartz-Ulvospinel-Ilmenite-Pyroxene) is used to project self-consistent equilibrium temperatures and oxygen fugacities for samples reset due to hematite loss from the ilmenite grains. These projected temperatures and oxygen fugacities agree reasonably well with non-reset samples. The mean projected temperature is 830 {plus minus} 40C (1{sigma}). This agreement strongly supports the conclusion that low titaniferous magnetite-ilmenite temperatures (down to 485C) and accompanying low-oxygen fugacities are the result of hematite loss from the ilmenite grains at some time after granulite-facies metamorphism.

  10. The Mineralogy, Geochemistry, and Redox State of Multivalent Cations During the Crystallization of Primitive Shergottitic Liquids at Various (f)O2. Insights into the (f)O2 Fugacity of the Martian Mantle and Crustal Influences on Redox Conditions of Martian Magmas.

    NASA Technical Reports Server (NTRS)

    Shearer, C. K.; Bell, A. S.; Burger, P. V.; Papike, J. J.; Jones, J.; Le, L.; Muttik, N.

    2016-01-01

    The (f)O2 [oxygen fugacity] of crystallization for martian basalts has been estimated in various studies to range from IW-1 to QFM+4 [1-3]. A striking geochemical feature of the shergottites is the large range in initial Sr isotopic ratios and initial epsilon(sup Nd) values. Studies by observed that within the shergottite group the (f)O2 [oxygen fugacity] of crystallization is highly correlated with these chemical and isotopic characteristics with depleted shergottites generally crystallizing at reduced conditions and enriched shergottites crystallizing under more oxidizing conditions. More recent work has shown that (f)O2 [oxygen fugacity] changed during the crystallization of these magmas from one order of magnitude in Y980459 (Y98) to several orders of magnitude in Larkman Nunatak 06319. These real or apparent variations within single shergottitic magmas have been attributed to mixing of a xenocrystic olivine component, volatile loss-water disassociation, auto-oxidation during crystallization of mafic phases, and assimilation of an oxidizing crustal component (e.g. sulfate). In contrast to the shergottites, augite basalts such as NWA 8159 are highly depleted yet appear to be highly oxidized (e.g. QFM+4). As a first step in attempting to unravel petrologic complexities that influence (f)O2 [oxygen fugacity] in martian magmas, this study explores the effect of (f)O2 [oxygen fugacity] on the liquid line of descent (LLD) for a primitive shergottite liquid composition (Y98). The results of this study will provide a fundamental basis for reconstructing the record of (f)O2 [oxygen fugacity] in shergottites and other martian basalts, its effect on both mineral chemistries and valence state partitioning, and a means for examining the role of crystallization (and other more complex processes) on the petrologic linkages between olivine-phyric and pyroxene-plagioclase shergottites.

  11. Photocatalytic oxygen evolution from low-bandgap conjugated microporous polymer nanosheets: a combined first-principles calculation and experimental study.

    PubMed

    Wang, Lei; Wan, Yangyang; Ding, Yanjun; Niu, Yuchen; Xiong, Yujie; Wu, Xiaojun; Xu, Hangxun

    2017-03-23

    Nanostructured semiconducting polymers have emerged as a very promising class of metal-free photocatalytic materials for solar water splitting. However, they generally exhibit low efficiency and lack the ability to utilize long-wavelength photons in a photocatalytic oxygen evolution reaction (OER). Here, based on first-principles calculations, we reveal that the two-dimensional (2D) aza-fused conjugated microporous polymer (aza-CMP) with a honeycomb network is a semiconductor with novel layer-dependent electronic properties. The bandgap of the as-synthesized aza-CMP nanosheets is measured to be 1.22 eV, suggesting that they can effectively boost light absorption in the visible and near infrared (NIR) region. More importantly, aza-CMP also possesses a valence band margin suitable for a photocatalytic OER. Taking advantage of the 2D layered nanostructure, we further show that the exfoliated ultrathin aza-CMP nanosheets can exhibit a three-fold enhancement in the photocatalytic OER. After deposition of a Co(OH)2 cocatalyst, the hybrid Co(OH)2/aza-CMP photocatalyst exhibits a markedly improved performance for photocatalytic O2 evolution. Furthermore, first-principles calculations reveal that the photocatalytic O2 evolution reaction is energetically feasible for aza-CMP nanosheets under visible light irradiation. Our findings reveal that nanostructured polymers hold great potential for photocatalytic applications with efficient solar energy utilization.

  12. Fugacity analysis of polycyclic aromatic hydrocarbons between microplastics and seawater

    NASA Astrophysics Data System (ADS)

    Lee, Hwang; Chang, Sein; Kim, Seung-Kyu; Kwon, Jung-Hwan

    2017-03-01

    Recently, the accumulation of plastic debris in the marine environment has become a great concern worldwide. Although plastics are biologically and chemically inert, plastic debris has been suspected of causing adverse effects on ecosystems due to the increase in reactivity by size reduction and/or micropollutants associated with plastics. Because of the high sorption capacity of microplastics toward organic micropollutants, it is suspected that microplastics may play roles in the distribution and fate of micropollutants. In order to quantitatively evaluate the "net flow" of environmental contaminants in water-plastic-organism systems, a fugacity analysis was conducted using concentrations of polycyclic aromatic hydrocarbons (PAHs) in open oceans and in polyethylene as a representative material of plastic debris. Ratio of fugacity in polyethylene to that in seawater showed a decreasing trend with increasing partition coefficient between polyethylene and seawater (KPE/sw). This indicates that phase equilibrium between polyethylene and seawater is not attained for higher molecular weight PAHs. Disequilibrium of high molecular weight PAHs suggests that transfer from seawater to plastic debris is thermodynamically driven and the role of plastic debris as a vector to transfer them to living organisms would be minimal. However, additives may slowly migrate from plastics into the environment causing potentially serious effects on ecosystems.

  13. Fugacity analysis of polycyclic aromatic hydrocarbons between microplastics and seawater

    NASA Astrophysics Data System (ADS)

    Lee, Hwang; Chang, Sein; Kim, Seung-Kyu; Kwon, Jung-Hwan

    2017-01-01

    Recently, the accumulation of plastic debris in the marine environment has become a great concern worldwide. Although plastics are biologically and chemically inert, plastic debris has been suspected of causing adverse effects on ecosystems due to the increase in reactivity by size reduction and/or micropollutants associated with plastics. Because of the high sorption capacity of microplastics toward organic micropollutants, it is suspected that microplastics may play roles in the distribution and fate of micropollutants. In order to quantitatively evaluate the "net flow" of environmental contaminants in water-plastic-organism systems, a fugacity analysis was conducted using concentrations of polycyclic aromatic hydrocarbons (PAHs) in open oceans and in polyethylene as a representative material of plastic debris. Ratio of fugacity in polyethylene to that in seawater showed a decreasing trend with increasing partition coefficient between polyethylene and seawater (KPE/sw). This indicates that phase equilibrium between polyethylene and seawater is not attained for higher molecular weight PAHs. Disequilibrium of high molecular weight PAHs suggests that transfer from seawater to plastic debris is thermodynamically driven and the role of plastic debris as a vector to transfer them to living organisms would be minimal. However, additives may slowly migrate from plastics into the environment causing potentially serious effects on ecosystems.

  14. Electrochemical measurements and thermodynamic calculations of redox equilibria in pallasite meteorites - Implications for the eucrite parent body

    NASA Technical Reports Server (NTRS)

    Righter, Kevin; Arculus, Richard J.; Paslick, Cassi; Delano, John W.

    1990-01-01

    The intrinsic oxygen fugacity (IOF) of olivine separates from the Salta, Springwater, and Eagle Station pallasites was measured between 850 and 1150 C using oxygen-specific solid zirconia electrolytes at 100,000 Pa. Thermodynamic calculations of redox equilibria involving equalibrium pallasite assemblages are in good agreement with the experimental results and provide a lower limit to pallasite redox stability; others involving disequilibrium assemblages, suggest that pallasites experienced localized, late-stage oxidation and reduction effects. Consideration of the redox buffer metal-olivine-orthopyroxene utilizing calculated Eucrite Parent Body (EPB) mantle phase compositions indicates that small redox gradients may have existed in the EPB. Such gradients may have produced strong compositional variation within the EPB. In addition, there is apparently significant redox heterogeneity in the source area of Eagle Station Trio pallasites and Bocaiuva iron meteorites.

  15. Partial pressures of oxygen, phosphorus and fluorine in some lunar lavas

    NASA Technical Reports Server (NTRS)

    Nash, W. P.; Hausel, W. D.

    1973-01-01

    Lunar sample 14310 is a feldspar-rich basalt which shows no evidence of shock deformation or recrystallization. Pyroxenes include Mg-rich orthopyroxene, pigeonite and augite; pyroxferroite occurs in the interstitial residuum. Plagioclase feldspars are zoned from An(96) to An(67), and variations in feldspar compositions do not necessarily indicate loss of Na during eruption of the lava. Opaque phases include ilmenite, ulvospinel, metallic iron, troilite, and schreibersite. Both whitlockite and apatite are present, and the interstitial residua contain baddeleyite, tranquillityite and barium-rich sanidine. Theoretical calculations provide estimates of partial pressures of oxygen, phosphorus, and fluorine in lunar magmas. In general, partial pressures of oxygen are restricted by the limiting assemblages of iron-wuestite and ilmenite-iron-rutile; phosphorus partial pressures are higher in lunar magmas than in terrestrial lavas. The occurrence of whitlockite indicates significantly lower fugacities of fluorine in lunar magmas than in terrestrial magmas.

  16. Screening nitrogen-rich bases and oxygen-rich acids by theoretical calculations for forming highly stable salts.

    PubMed

    Zhang, Xueli; Gong, Xuedong

    2014-08-04

    Nitrogen-rich heterocyclic bases and oxygen-rich acids react to produce energetic salts with potential application in the field of composite explosives and propellants. In this study, 12 salts formed by the reaction of the bases 4-amino-1,2,4-trizole (A), 1-amino-1,2,4-trizole (B), and 5-aminotetrazole (C), upon reaction with the acids HNO3 (I), HN(NO2 )2 (II), HClO4 (III), and HC(NO2 )3 (IV), are studied using DFT calculations at the B97-D/6-311++G** level of theory. For the reactions with the same base, those of HClO4 are the most exothermic and spontaneous, and the most negative Δr Gm in the formation reaction also corresponds to the highest decomposition temperature of the resulting salt. The ability of anions and cations to form hydrogen bonds decreases in the order NO3 (-) >N(NO2 )2 (-) >ClO4 (-) >C(NO2 )3 (-) , and C(+) >B(+) >A(+) . In particular, those different cation abilities are mainly due to their different conformations and charge distributions. For the salts with the same anion, the larger total hydrogen-bond energy (EH,tot ) leads to a higher melting point. The order of cations and anions on charge transfer (q), second-order perturbation energy (E2 ), and binding energy (Eb ) are the same to that of EH,tot , so larger q leads to larger E2 , Eb , and EH,tot . All salts have similar frontier orbitals distributions, and their HOMO and LUMO are derived from the anion and the cation, respectively. The molecular orbital shapes are kept as the ions form a salt. To produce energetic salts, 5-aminotetrazole and HClO4 are the preferred base and acid, respectively.

  17. Accelerated materials design of Na0.5Bi0.5TiO3 oxygen ionic conductors based on first principles calculations.

    PubMed

    He, Xingfeng; Mo, Yifei

    2015-07-21

    We perform a first principles computational study of designing the Na0.5Bi0.5TiO3 (NBT) perovskite material to increase its oxygen ionic conductivity. In agreement with the previous experiments, our computation results confirm fast oxygen ionic diffusion and good stability of the NBT material. The oxygen diffusion mechanisms in this new material were systematically investigated, and the effects of local atomistic configurations and dopants on oxygen diffusion were revealed. Novel doping strategies focusing on the Na/Bi sublattice were predicted and demonstrated by the first principles calculations. In particular, the K doped NBT compound achieved good phase stability and an order of magnitude increase in oxygen ionic conductivity of up to 0.1 S cm(-1) at 900 K compared to the previous Mg doped compositions. This study demonstrated the advantages of first principles calculations in understanding the fundamental structure-property relationship and in accelerating the materials design of the ionic conductor materials.

  18. 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

  19. Lipid Extraction and the Fugacity of Stable Isotope Values

    NASA Astrophysics Data System (ADS)

    Padula, V.; Causey, D.; Wolf, N.; Welker, J. M.

    2013-12-01

    Stable isotope analysis of blood, feathers, and other tissues are often used to infer migration patterns, diet composition and trophic status of seabirds. Tissues contain variable amounts of lipids that are depleted in the heavy carbon isotope (13C) and may introduce a bias in these values. There is evidence that lipid extraction may affect other stable isotope ratios, such as δ15N. Consequently, correction factors need to be applied to appropriately interpret δ13C and δ15N values for individual species and tissue type. In this study, we collected seven species of seabirds from the Near Islands, the western most group of islands in the Aleutian Island archipelago. We sampled kidney, liver, heart and muscle samples from each bird and after freeze drying, individual tissue samples were divided into two subsamples. We left one subsample unaltered and extracted lipids from the other subsample using a 2:1 chloroform-methanol solution. We found that the change in δ13C values after lipid extraction (Δδ13C) varied widely among categories (eg., species, tissue type) from 0 - 4 ‰, while Δδ15N values ranged from 0 to 2‰. Notably, within category variation was nonsignificant and the Δδ values were linear against the covariant C:N ratio of the isotopic data, which allows us to use arithmetic corrections for categorical values. Our data strongly indicate that the effects of lipid extraction on stable isotopic values, while linear within category, vary widely by species, tissue, geographic area, year of collection, and isotope. Fugacity is usually employed as a thermodynamic quantity related to the chemical potential or activity that characterizes the escaping tendency from a phase (eg. Mackay & Paterson 1982). Here we use fugacity in the earlier, broader sense of fleeting, transitory, or instable states (eg., S. Johnson 1751), and its measure may be approximated by the higher order variance of Δδ13C and Δδ15N among data categories. Clearly, understanding the

  20. Electrostatic Waves in Dense Dusty Plasmas with High Fugacity

    NASA Astrophysics Data System (ADS)

    Rao, N. N.

    Propagation of electrostatic dust modes has been reviewed in the light of the concept of dust fugacity defined by f≡4πnd0λD2R, where nd0 and R are the dust number density and the grain size (radius) while the plasma Debye length (λD) is given through λD-2=λDe-2+λDi-2. Dusty plasmas are defined to be tenuous, dilute or dense when f≪1, ˜1, or ≫1, respectively. Attention is focused on “Dust-Acoustic Waves” (DAWs) and “Dust-Coulomb Waves” (DCWs) which exist in the tenuous (f≪1) and the dense (f≫1) regimes, respectively. A simple physical picture of the DCWs has been proposed in terms of an effective pressure called “Coulomb Pressure defined by PC≡nd0qd02/R, where qd0 is the grain charge. In the lowest order, the DCW phase speed is given by ω/k=PC/ρdδ, where ρd≡nd0md is the dust mass density and δ≡ω2/ω1 is the ratio of charging frequencies. Thus, DCWs which are driven by the Coulomb pressure can be considered as the electrostatic analogue of hydromagnetic (Alfvén or magnetoacoustic) modes which are driven by magnetic field pressure. In the dilute regime, the two waves loose their identities and merge into a single mode, which may be called “Dust Charge-Density Wave” (DCDW). When the grains are closest, DCW dispersion relation is identical with that of “Dust-Lattice Waves” (DLWs). Dense dusty plasmas are governed by a new scale-length defined by λR≡1/4πnd0Rδ, which characterizes the effective shielding length due to grain collective interactions. The scale-length λR plays a fundamental role in dense dusty plasmas, which is very similar to that of the Debye length λD in the tenuous regime. The two scale-lengths are related to the fugacity through fδ≡λD2/λR2. The frequency spectrum as well as the damping rates for various dust modes have been analytically obtained, and compared with the numerical solutions of the kinetic (Vlasov) dispersion relation.

  1. A Compensated-Redlich-Kwong (CORK) equation for volumes and fugacities of CO2 and H2O in the range 1 bar to 50 kbar and 100 1600°C

    NASA Astrophysics Data System (ADS)

    Holland, Tim; Powell, Roger

    1991-12-01

    We present a simple virial-type extension to the modified Redlich-Kwong (MRK) equation for calculation of the volumes and fugacities of H2O and CO2 over the pressure range 0.001 50 kbar and 100 to 1400°C (H2O) and 100 to 1600°C (CO2). This extension has been designed to: (a) compensate for the tendency of the MRK equation to overestimate volumes at high pressures, and (b) accommodate the volume behaviour of coexisting gas and liquid phases along the saturation curve. The equation developed for CO2 may be used to derive volumes and fugacities of CO, H2, CH4, N2, O2 and other gases which conform to the corresponding states principle. For H2O the measured volumes of Burnham et al. are significantly higher in the range 4 10 kbar than those presented by other workers. For CO2 the volume behaviour at high pressures derived from published MRK equations are very different (larger volumes, steeper ( ∂P/ ∂T)V, and hence larger fugacities) from the virial-type equations of Saxena and Fei. Our CORK equation for CO2 yields fugacities which are in closer agreement with the available high pressure experimental decarbonation reactions.

  2. Oxygen-aromatic contacts in intra-strand base pairs: analysis of high-resolution DNA crystal structures and quantum chemical calculations.

    PubMed

    Jain, Alok; Krishna Deepak, R N V; Sankararamakrishnan, Ramasubbu

    2014-07-01

    Three-dimensional structures of biomolecules are stabilized by a large number of non-covalent interactions and some of them such as van der Waals, electrostatic and hydrogen bond interactions are well characterized. Delocalized π-electron clouds of aromatic residues are known to be involved in cation-π, CH-π, OH-π and π-π interactions. In proteins, many examples have been found in which the backbone carbonyl oxygen of one residue makes close contact with the aromatic center of aromatic residues. Quantum chemical calculations suggest that such contacts may provide stability to the protein secondary structures. In this study, we have systematically analyzed the experimentally determined high-resolution DNA crystal structures and identified 91 examples in which the aromatic center of one base is in close contact (<3.5Ǻ) with the oxygen atom of preceding (Group-I) or succeeding base (Group-II). Examples from Group-I are overwhelmingly observed and cytosine or thymine is the preferred base contributing oxygen atom in Group-I base pairs. A similar analysis of high-resolution RNA structures surprisingly did not yield many examples of oxygen-aromatic contact of similar type between bases. Ab initio quantum chemical calculations on compounds based on DNA crystal structures and model compounds show that interactions between the bases in base pairs with oxygen-aromatic contacts are energetically favorable. Decomposition of interaction energies indicates that dispersion forces are the major cause for energetically stable interaction in these base pairs. We speculate that oxygen-aromatic contacts in intra-strand base pairs in a DNA structure may have biological significance.

  3. Ab initio Calculation of Thermodynamic Data for Oxygenated Hydrocarbon Fuels and Radial Breakdown Species: R(OMe)n

    SciTech Connect

    Kubota, A; Pitz, W J; Westbrook, C K; Bozzelli, J; Glaude, P-A

    2001-03-23

    There has long been interest in the use of oxygenated hydrocarbon additives to conventional fuels. These oxygenates have been shown to reduce soot emissions in diesel engines and CO emissions in spark-ignition engines; and often allow diesel operation with decreased NO{sub x}. The current widely used additive, MTBE is targeted for elimination as a gasoline additive due to its damaging effects on the environment. This creates a need for alternative oxygenated additives; and more importantly, amplifies the importance to fully understand the thermochemical and kinetic properties on these oxyhydrocarbons fuels and for their intermediate and radical breakdown products. We use CBS-Q and density-functional methods with isodesmic reactions (with group balance when possible) to compute thermodynamic quantities for these species. We have studied hydrocarbons with multiple substituted methoxy groups. In several cases, multioxygenated species are evaluated that may have potential use as new oxygenated fuel additives. Thermodynamic quantities (H{sub 298}{sup 0}, S{sub 298}{sup 0}, C{sub p}(T)) as well as group additivity contributions for the new oxygenated groups are reported. We also report trends in bond-energies with increasing methoxy substitution.

  4. Fugacity superposition: a new approach to dynamic multimedia fate modeling.

    PubMed

    Hertwich, E G

    2001-08-01

    The fugacities, concentrations, or inventories of pollutants in environmental compartments as determined by multimedia environmental fate models of the Mackay type can be superimposed on each other. This is true for both steady-state (level III) and dynamic (level IV) models. Any problem in multimedia fate models with linear, time-invariant transfer and transformation coefficients can be solved through a superposition of a set of n independent solutions to a set of coupled, homogeneous first-order differential equations, where n is the number of compartments in the model. For initial condition problems in dynamic models, the initial inventories can be separated, e.g. by a compartment. The solution is obtained by adding the single-compartment solutions. For time-varying emissions, a convolution integral is used to superimpose solutions. The advantage of this approach is that the differential equations have to be solved only once. No numeric integration is required. Alternatively, the dynamic model can be simplified to algebraic equations using the Laplace transform. For time-varying emissions, the Laplace transform of the model equations is simply multiplied with the Laplace transform of the emission profile. It is also shown that the time-integrated inventories of the initial conditions problems are the same as the inventories in the steady-state problem. This implies that important properties of pollutants such as potential dose, persistence, and characteristic travel distance can be derived from the steady state.

  5. Calculation of hydrogen and oxygen uptake in fuel rod cladding during severe accidents using the integral diffusion method -- Final Design Report

    SciTech Connect

    Siefken, L.J.

    1999-05-01

    Final designs are described for models of hydrogen and oxygen uptake in fuel rod cladding during severe accidents. Calculation of the uptake involves the modeling of seven processes: (1) diffusion of oxygen from the bulk gas into the boundary layer at the external cladding surface, (2) diffusion from the boundary layer into the oxide layer, (3) diffusion from the inner surface of the oxide layer into the metallic part of the cladding, (4) uptake of hydrogen in the event that the cladding oxide layer is dissolved in a steam-starved region, (5) embrittlement of cladding due to hydrogen uptake, (6) cracking of cladding during quenching due to its embrittlement and (7) release of hydrogen from the cladding after cracking of the cladding. An integral diffusion method is described for calculating the diffusion processes in the cladding. Experimental results are presented that show a rapid uptake of hydrogen in the event of dissolution of the oxide layer and a rapid release of hydrogen in the event of cracking of the oxide layer. These experimental results are used as a basis for calculating the rate of hydrogen uptake and the rate of hydrogen release. A description is given of the implementation of the models for hydrogen and oxygen uptake and cladding embrittlement into the programming framework of the SCDAP/RELAP5/MOD3.3 code.

  6. Calculation of Hydrogen and Oxygen Uptake in Fuel Rod Cladding During Severe Accidents Using the Integral Diffusion Method - Final Design Report

    SciTech Connect

    Siefken, Larry James

    1999-06-01

    Final designs are described for models of hydrogen and oxygen uptake in fuel rod cladding during severe accidents. Calculation of the uptake involves the modeling of seven processes: (1) diffusion of oxygen from the bulk gas into the boundary layer at the external cladding surface, (2) diffusion from the boundary layer into the oxide layer, (3) diffusion from the inner surface of the oxide layer into the metallic part of the cladding, (4) uptake of hydrogen in the event that the cladding oxide layer is dissolved in a steam-starved region, (5) embrittlement of cladding due to hydrogen uptake, (6) cracking of cladding during quenching due to its embrittlement and (7) release of hydrogen from the cladding after cracking of the cladding. An integral diffusion method is described for calculating the diffusion processes in the cladding. Experimental results are presented that show a rapid uptake of hydrogen in the event of dissolution of the oxide layer and a rapid release of hydrogen in the event of cracking of the oxide layer. These experimental results are used as a basis for calculating the rate of hydrogen uptake and the rate of hydrogen release. A description is given of the implementation of the models for hydrogen and oxygen uptake and cladding embrittlement into the programming framework of the SCDAP/RELAP5/MOD3.3 code.

  7. Waves in dusty plasmas and the concept of fugacity

    NASA Astrophysics Data System (ADS)

    Rao, Nagesha N.

    2000-10-01

    The propagation of ultra low-frequency electrostatic modes in dusty plasmas has been reviewed in the light of the concept of dust fugacity (f ), which is defined by f≡4πnd0λD2R where nd0, λD and R are, respectively, the dust number density, the plasma Debye length and the grain size (radius). Dusty plasmas are defined to be tenuous, dilute or dense according as f<<1, ~1, or >>1, respectively. By using the fluid as well as the kinetic (Vlasov) theories, attention is focused on the ``Dust-Acoustic Waves'' (DAWs) and the ``Dust-Coulomb Waves'' (DCWs) which exist in the tenuous and the dense regimes, respectively. Unlike the DAWs which exist even for constant grain charge, the DCWs are the normal modes associated with grain charge fluctuations, and are driven by an effective pressure called ``Coulomb Pressure''. They can be considered as the electrostatic analogue of the hydromagnetic (Alfvén or magnetoacoustic) modes which are driven by the magnetic field pressure. In the dilute regime, the two modes merge into a single mode, which may be called the ``Dust Charge-Density Wave'' (DCDW). When the grains are closest, the DCW dispersion relation is identical with that of the ``Dust-Lattice Waves'' (DLWs). Dense dusty plasmas are shown to be governed by a new scale-length defined by λR≡1/4πnd0Rδ, where δ is a parameter related to the charging frequencies. The scale-length λR characterizes the effective shielding length due to the collective grain interactions, and plays a fundamental role in dense dusty plasmas, which is very similar to that of the Debye length (λD) of the tenuous regime. The frequency spectrum as well as the damping rates for the various dust modes have been analytically obtained, and compared with the numerical results. .

  8. Utilizing Polymer-Coated Vials to Illustrate the Fugacity and Bioavailability of Chlorinated Pesticide Residues in Contaminated Soils

    ERIC Educational Resources Information Center

    Andrade, Natasha A.; McConnell, Laura L.; Torrents, Alba; Hapeman, Cathleen J.

    2013-01-01

    Fugacity and bioavailability can be used to facilitate students' understanding of potential environmental risks associated with toxic chemicals and, therefore, should be incorporated in environmental chemistry and science laboratories. Although the concept of concentration is easy to grasp, fugacity and bioavailability can be challenging…

  9. Optical noninvasive calculation of hemoglobin components concentrations and fractional oxygen saturation using a ring-scattering pulse oximeter

    NASA Astrophysics Data System (ADS)

    Abdallah, Omar; Stork, Wilhelm; Muller-Glaser, Klaus

    2004-06-01

    The deficiencies of the currently used pulse oximeter are discussed in diverse literature. A hazardous pitfalls of this method is that the pulse oximeter will not detect carboxyhemoglobin (COHb) and methemoglobin (metHb) concentrations. This leads to incorrect measurement of oxygen saturation by carbon monoxide poisoning and methemoglobinemia. Also the total hemoglobin concentration will not be considered and can only be measured in-vitro up to now. A second pitfall of the standard pulse oximetry is that it will not be able to show a result by low perfusion of tissues. This case is available inter alia when the patient is under shock or has a low blood pressure. The new non-invasive system we designed measures the actual (fractional) oxygen saturation and hemoglobin concentration. It will enable us also to measure COHb and metHb. The measurement can be applied at better perfused body central parts. Four or more light emitting diodes (LEDs) or laser diodes (LDs) and five photodiodes (PDs) are used. The reflected light signal detected by photodiodes is processed using a modified Lambert-Beer law (I=I0×e-α.d ). According to this law, when a non scattering probe is irradiated with light having the incident intensity I0, the intensity of transmitted light I decays exponentially with the absorption coefficient a of that probe and its thickness d. Modifications of this law have been performed following the theoretical developed models in literature, Monte Carlo simulation and experimental measurement.

  10. Size and structure effects of Pt{sub N} (N = 12 − 13) clusters for the oxygen reduction reaction: First-principles calculations

    SciTech Connect

    Rodríguez-Kessler, P. L.; Rodríguez-Domínguez, A. R.

    2015-11-14

    Size and structure effects on the oxygen reduction reaction on Pt{sub N} clusters with N = 12–13 atoms have been investigated using periodic density functional theory calculations with the generalized gradient approximation. To describe the catalytic activity, we calculated the O and OH adsorption energies on the cluster surface. The oxygen binding on the 3-fold hollow sites on stable Pt{sub 12−13} cluster models resulted more favorable for the reaction with O, compared with the Pt{sub 13}(I{sub h}) and Pt{sub 55}(I{sub h}) icosahedral particles, in which O binds strongly. However, the rate-limiting step resulted in the removal of the OH species due to strong adsorptions on the vertex sites, reducing the utility of the catalyst surface. On the other hand, the active sites of Pt{sub 12−13} clusters have been localized on the edge sites. In particular, the OH adsorption on a bilayer Pt{sub 12} cluster is the closest to the optimal target; with 0.0-0.2 eV weaker than the Pt(111) surface. However, more progress is necessary to activate the vertex sites of the clusters. The d-band center of Pt{sub N} clusters shows that the structural dependence plays a decisive factor in the cluster reactivity.

  11. Characterization of the Sr(2+)- and Cd(2+)-Substituted Oxygen-Evolving Complex of Photosystem II by Quantum Mechanics/Molecular Mechanics Calculations.

    PubMed

    Pitari, Fabio; Bovi, Daniele; Narzi, Daniele; Guidoni, Leonardo

    2015-09-29

    The Mn4CaO5 cluster in the oxygen-evolving complex is the catalytic core of the Photosystem II (PSII) enzyme, responsible for the water splitting reaction in oxygenic photosynthesis. The role of the redox-inactive ion in the cluster has not yet been fully clarified, although several experimental data are available on Ca2+-depleted and Ca2+-substituted PSII complexes, indicating Sr2+-substituted PSII as the only modification that preserves oxygen evolution. In this work, we investigated the structural and electronic properties of the PSII catalytic core with Ca2+ replaced with Sr2+ and Cd2+ in the S2 state of the Kok−Joliot cycle by means of density functional theory and ab initio molecular dynamics based on a quantum mechanics/ molecular mechanics approach. Our calculations do not reveal significant differences between the substituted and wild-type systems in terms of geometries, thermodynamics, and kinetics of two previously identified intermediate states along the S2 to S3 transition, namely, the open cubane S2 A and closed cubane S2 B conformers. Conversely, our calculations show different pKa values for the water molecule bound to the three investigated heterocations. Specifically, for Cd-substituted PSII, the pKa value is 5.3 units smaller than the respective value in wild type Ca-PSII. On the basis of our results, we conclude that, assuming all the cations sharing the same binding site, the induced difference in the acidity of the binding pocket might influence the hydrogen bonding network and the redox levels to prevent the further evolution of the cycle toward the S3 state.

  12. Oxygen Fugacity of the Martian Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium

    NASA Technical Reports Server (NTRS)

    Musselwhite, D. S.; Jnes, J. H.; Shearer, C.

    2004-01-01

    This study is part of an ongoing effort to calibrate the pyroxene/melt REE oxybarometer for conditions relevant to the martian meteorites. These efforts have been motivated by reports of redox variations among the shergottites . We have conducted experiments on martian composition pigeonite/melt rare earth element partitioning as a function of fO2.

  13. Oxygen Fugacity of the Martian Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium

    NASA Technical Reports Server (NTRS)

    Musselwhite, S.; Jones, J. H.; Shearer, C.

    2004-01-01

    This study is part of an ongoing effort to calibrate the pyroxene/melt Eu oxybarometer for conditions relevant to the martian meteorites. There is fairly good agreement between a determinations using equilibria between Fe-Ti oxides and the estimates from Eu anomalies in shergottite augites in tenns of which meteorites are more or less oxidized. The Eu calibration was for angrite composition pyroxenes which are rather extreme. However, application of a calibration for martian composition augites 113 does not significantly reduce the discrepancy between the two methods. One possible reason for this discrepancy is that augites are non-liquidus. The use of pigeonite rather than augite as the oxy-barometer phase is considered. We have conducted experiments on martian composition pigeonite/melt REE partitioning as a function of fO2.

  14. Oxygen Fugacity of the Martian Mantle From Pyroxene/Melt Partitioning of REE

    NASA Technical Reports Server (NTRS)

    Musselwhite, D. S.; Jones, J. H.

    2003-01-01

    This study is part of an ongoing effort to calibrate the pyroxene/melt REE oxybarometer for conditions relevant to the martian meteorites. Redox variations have been reported among the shergottites. Wadhwa used the Eu and Gd augite/melt partitioning experiments of McKay, designed for the LEW86010 angrite, to infer a range of fo2 for the shergottites. Others inferred fo2 using equilibria between Fe-Ti oxides. There is fairly good agreement between the Fe-Ti oxide determinations and the estimates from Eu anomalies in terms of which meteorites are more or less oxidized. The Eu anomaly technique and the Fe-Ti oxide technique both essentially show the same trend, with Shergotty and Zagami being the most oxidized and QUE94201 and DaG 476 being the most reduced. Thus, the variation in fo2 appears to be both real and substantive. However, although the redox trends indicated by the two techniques are similar, there is as much as two log unit offset between the results of three researchers. One explanation for this offset is that the Eu calibration used for the shergottites was actually designed for the LEW86010 angrite, a silica-undersaturated basalt whose pyroxene (diopside) compositions are rather extreme. To correct this, experiments have been conducted on the redox relationship of Eu partitioning relative to Sm and Gd for pyroxene/melt compositions more relevant to Martian meteorites. We report here preliminary results for experiments on pigeonite/melt partitioning as a function of fO2.

  15. Studies of the Effects of Oxygen Fugacity on Diffusion in Pyroxenes

    NASA Astrophysics Data System (ADS)

    Cherniak, D. J.

    2002-05-01

    Over the past several years, we have explored the dependence of fO2 on diffusion in natural Fe-bearing pyroxenes, with emphasis on investigation of Pb diffusion. In these studies (Cherniak, 1998; 2001) we have found a positive dependence on fO2 for diffusion in both clinopyroxene and orthopyroxene. The dependencies can be described with values of m ranging from 0.14 to 0.20 (for D proportional to (fO2)m), similar to the value of +3/16 for m for diffusion controlled by cation vacancies, estimated from point defect models for diopside (Jaoul and Raterron, 1994), where the majority point defects are Mg and Si vacancies and Fe+3. We continue this work with a synthetic, Fe-free diopside (Sneeringer et al., 1984) to explore whether defects due to the presence of Fe do indeed exert a significant influence over transport properties under differing fO2. Experiments were conducted in a manner similar to that for our earlier work, using a double silica glass capsule assembly. Sources of diffusant consisted of mixtures of PbS powder and ground synthetic diopside, with Pb diffusional uptake profiles measured by Rutherford Backscattering (RBS). The results for Pb diffusion in the synthetic diopside yield the following Arrhenius relation, over the temperature range 850-1050C, buffered at QFM: DPb = 4.6x10-7 exp(- 364 +/- 43 kJ mol-1/RT) m2sec2 These diffusivities are slower than those for natural diopside, but the activation energy for diffusion is similar to that determined for several other pyroxenes (350-390 kJ/mol, Cherniak, 2001). Interestingly, there appears to be little effect of fO2 on Pb diffusivities in synthetic Fe-free diopside, as experiments run with IW and MH buffers yield similar results to experiments run at QFM. We are currently exploring the effects of fO2 on diffusion of other elements in a range of pyroxene compositions, and will also present a progress report of this work. Cherniak D.J. (1998) Chem. Geol. 150, 105-117; Cherniak D.J. (2001) Chem. Geol. 177, 381-397; Jaoul O., P. Raterron (1994) JGR 99, 9423-9439; Sneeringer M., S.R. Hart, N.Shimizu (1984) GCA 48, 1589-1608.

  16. Use of Physicochemical Parameters to Assess the Environmental Fate of Organic Pollutants: The Fugacity Model

    ERIC Educational Resources Information Center

    Domenech, Xavier; Ayllon, Jose Antonio; Peral, Jose

    2006-01-01

    The environmental fate and behavior of different organic pollutants based on the qualitative analysis of thermodynamic and kinetic data is presented. The Fugacity model allows the use of different partition constants in an easy way, to determine the distribution of chemical between different phases in equilibrium of an environmental system.

  17. Spatial distribution of neutral oxygen vacancies on ZnO nanowire surfaces: An investigation combining confocal microscopy and first principles calculations

    NASA Astrophysics Data System (ADS)

    Mun Wong, Kin; Alay-e-Abbas, S. M.; Fang, Yaoguo; Shaukat, A.; Lei, Yong

    2013-07-01

    A qualitative approach using room-temperature confocal microscopy is employed to investigate the spatial distribution of shallow and deep oxygen vacancy (VO) concentrations on the polar (0001) and non-polar (101¯0) surfaces of zinc oxide (ZnO) nanowires (NWs). Using the spectral intensity variation of the confocal photoluminescence of the green emission at different spatial locations on the surface, the VO concentrations of an individual ZnO NW can be obtained. The green emission at different spatial locations on the ZnO NW polar (0001) and non-polar (101¯0) surfaces is found to have maximum intensity near the NW edges, decreasing to a minimum near the NW center. First-principles calculations using simple supercell-slab (SS) models are employed to approximate/model the defects on the ZnO NW (101¯0) and (0001) surfaces. These calculations give increased insight into the physical mechanism behind the green emission spectral intensity and the characteristics of an individual ZnO NW. The highly accurate density functional theory (DFT)-based full-potential linearized augmented plane-wave plus local orbitals (FP-LAPW + lo) method is used to compute the defect formation energy (DFE) of the SSs. Previously, using these SS models, it was demonstrated through the FP-LAPW + lo method that in the presence of oxygen vacancies at the (0001) surface, the phase transformation of the SSs in the graphite-like structure to the wurtzite lattice structure will occur even if the thickness of the graphite-like SSs are equal to or less than 4 atomic graphite-like layers [Wong et al., J. Appl. Phys. 113, 014304 (2013)]. The spatial profile of the neutral VO DFEs from the DFT calculations along the ZnO [0001] and [101¯0] directions is found to reasonably explain the spatial profile of the measured confocal luminescence intensity on these surfaces, leading to the conclusion that the green emission spectra of the NWs likely originate from neutral oxygen vacancies. Another significant

  18. Fugacity and activity analysis of the bioaccumulation and environmental risks of decamethylcyclopentasiloxane (D5).

    PubMed

    Gobas, Frank A P C; Xu, Shihe; Kozerski, Gary; Powell, David E; Woodburn, Kent B; Mackay, Don; Fairbrother, Anne

    2015-12-01

    As part of an initiative to evaluate commercial chemicals for their effects on human and environmental health, Canada recently evaluated decamethylcyclopentasiloxane (D5; CAS no. 541-02-06), a high-volume production chemical used in many personal care products. The evaluation illustrated the challenges encountered in environmental risk assessments and the need for the development of better tools to increase the weight of evidence in environmental risk assessments. The present study presents a new risk analysis method that applies thermodynamic principles of fugacity and activity to express the results of field monitoring and laboratory bioaccumulation and toxicity studies in a comprehensive risk analysis that can support risk assessments. Fugacity and activity ratios of D5 derived from bioaccumulation measures indicate that D5 does not biomagnify in food webs, likely because of biotransformation. The fugacity and activity analysis further demonstrates that reported no-observed-effect concentrations of D5 normally cannot occur in the environment. Observed fugacities and activities in the environment are, without exception, far below those corresponding with no observed effects, in many cases by several orders of magnitude. This analysis supports the conclusion of the Canadian Board of Review and the Minister of the Environment that D5 does not pose a danger to the environment. The present study further illustrates some of the limitations of a persistence-bioaccumulation-toxicity-type criteria-based risk assessment approach and discusses the merits of the fugacity and activity approach to increase the weight of evidence and consistency in environmental risk assessments of commercial chemicals.

  19. Calculating alveolar capillary conductance and pulmonary capillary blood volume: comparing the multiple- and single-inspired oxygen tension methods

    PubMed Central

    Ceridon, Maile L.; Beck, Kenneth C.; Olson, Thomas P.; Bilezikian, Jordan A.

    2010-01-01

    Key elements for determining alveolar-capillary membrane conductance (Dm) and pulmonary capillary blood volume (Vc) from the lung diffusing capacity (Dl) for carbon monoxide (DlCO) or for nitric oxide (DlNO) are the reaction rate of carbon monoxide with hemoglobin (θCO) and the DmCO/DlNO relationship (α-ratio). Although a range of values have been reported, currently there is no consensus regarding these parameters. The study purpose was to define optimal parameters (θCO, α-ratio) that would experimentally substantiate calculations of Dm and Vc from the single-inspired O2 tension [inspired fraction of O2 (FiO2)] method relative to the multiple-FiO2 method. Eight healthy men were studied at rest and during moderate exercise (80-W cycle). Dm and Vc were determined by the multiple-FiO2 and single-FiO2 methods (rebreathe technique) and were tabulated by applying previously reported θCO equations (both methods) and by varying the α-ratio (single-FiO2 method) from 1.90 to 2.50. Values were then compared between methods throughout the examined α-ratios. Dm and Vc were critically dependent on the applied θCO equation. For the multiple-FiO2 method, Dm was highly variable between θCO equations (rest and exercise); the range of Vc was less widespread. For the single-FiO2 method, the θCO equation by Reeves and Park (1992) combined with an α-ratio between 2.08 and 2.26 gave values for Dm and Vc that most closely matched those from the multiple-FiO2 method and were also physiologically plausible compared with predicted values. We conclude that the parameters used to calculate Dm and Vc values from the single-FiO2 method (using DlCO and DlNO) can significantly influence results and should be evaluated within individual laboratories to obtain optimal values. PMID:20538842

  20. Factors affecting the accuracy of near-infrared spectroscopy concentration calculations for focal changes in oxygenation parameters

    NASA Technical Reports Server (NTRS)

    Strangman, Gary; Franceschini, Maria Angela; Boas, David A.; Sutton, J. P. (Principal Investigator)

    2003-01-01

    Near-infrared spectroscopy (NIRS) can be used to noninvasively measure changes in the concentrations of oxy- and deoxyhemoglobin in tissue. We have previously shown that while global changes can be reliably measured, focal changes can produce erroneous estimates of concentration changes (NeuroImage 13 (2001), 76). Here, we describe four separate sources for systematic error in the calculation of focal hemoglobin changes from NIRS data and use experimental methods and Monte Carlo simulations to examine the importance and mitigation methods of each. The sources of error are: (1). the absolute magnitudes and relative differences in pathlength factors as a function of wavelength, (2). the location and spatial extent of the absorption change with respect to the optical probe, (3). possible differences in the spatial distribution of hemoglobin species, and (4). the potential for simultaneous monitoring of multiple regions of activation. We found wavelength selection and optode placement to be important variables in minimizing such errors, and our findings indicate that appropriate experimental procedures could reduce each of these errors to a small fraction (<10%) of the observed concentration changes.

  1. Respirometric kinetic parameter calculations of a batch jet loop bioreactor treating leachate and oxygen uptake rate estimation by DTM.

    PubMed

    Ince, M; Yildiz, F; Engin, G Onkal; Engin, S N; Keskinler, B

    2008-05-30

    A novel circulating jet loop bioreactor adapted for organic matter oxidation has been designed and constructed. In this study, the input was leachate samples collected from Kemerburgaz Odayeri waste landfill site located on the European side of Istanbul. Controlling the jet loop bioreactor to realize high rates of purification depends on maintaining the appropriate loadings and operating conditions. This requires collecting various system data to estimate the dynamics of the system satisfactorily with the aim of keeping certain parameters within the specified range. The differential transform method (DTM) based solution of the state equations reveals the current state of the process so that any deviation in the system parameters can be immediately detected and regulated accordingly. The respirometric method for kinetic parameter calculations for biodegradation has been used for some time. In many studies, the respirometer was designed separately, usually in bench-scale. However, when a separate respirometer is used, the scale effect and parameters that affect the hydrodynamic structure of the system should be taken into consideration. In this study, therefore, the jet loop reactor itself was used as a respirometer. Thus, the kinetic parameters found reflecting the characteristics of microorganisms used for biodegradation would be more realistic. If the main reactor, here the jet loop reactor, would be used as the respirometer, the kinetic parameter changes can easily be monitored in the long run. Using the bioreactor as a respirometer, the most important kinetic parameters, Ks, kd and micromax were found to be 11,000 mg L(-1), 0.019 day(-1), and 0.21 day(-1), respectively. The stoichiometric coefficient, Y, was found to be 0.28 gr gr(-1) for the present system.

  2. The Calculation for Saturated Solubility of Oxygen in Mn-Si Melts Equilibrated with MnO-SiO2 Slags

    NASA Astrophysics Data System (ADS)

    Han, Pei-Wei; Wang, Hai-Juan; Chu, Shao-Jun

    2017-01-01

    The MnO-SiO2 slag in equilibrium with Mn-Si melts with a Si molar ratio between 0.1 and 0.3 at 1,700 K was a single liquid phase. However, it was liquid phase saturated with solid MnO or solid SiO2 in the case of XSi less than 0.1 or greater than 0.3, respectively. Based on a subregular solution model, the calculated saturated solubility of oxygen in Mn-Si melts was 0.0236 mass % in pure manganese at 1,700 K and increased with the increasing silicon in the range of XSi from 0.1 to 0.3. However, the saturated solubility of oxygen decreases as the silicon exceeded 0.3, and the minimum solubility was 0.0041 mass % in pure silicon at 1,700 K. The results could be used to predict the compositions of endogenous oxide inclusions and evaluate the cleanliness of manganese ferroalloy.

  3. Enhanced methanol electro-oxidation and oxygen reduction reaction performance of ultrafine nanoporous platinum-copper alloy: Experiment and density functional theory calculation

    NASA Astrophysics Data System (ADS)

    Sun, Junzhe; Shi, Jun; Xu, Junling; Chen, Xiaoting; Zhang, Zhonghua; Peng, Zhangquan

    2015-04-01

    Novel ultrafine nanoporous Pt-Cu alloy with a Pt:Cu stoichiometric ratio of 3:1 (np-Pt3Cu) has been prepared by mechanical alloying and subsequent two-step chemical dealloying. The obtained np-Pt3Cu has uniform and bicontinuous ligament(metal)-channel(void) structure with the ligament size of 3.3 ± 0.7 nm. To explore its potential application in energy conversion reactions, the np-Pt3Cu alloy has been examined as electrocatalyst for the operating reactions in direct methanol fuel cells (DMFCs). Compared with the commercial JM Pt/C, a benchmark catalyst extensively used in fuel cell research, the np-Pt3Cu alloy demonstrates better performance in both the methanol electro-oxidation and oxygen reduction reactions in acidic medium. Theoretical calculations reveal that the electronic structure of Pt has been modified with the shift of Pt d-band center due to alloying with Cu, which can decrease CO poisoning and enhance the methanol oxidation and oxygen reduction reaction activities.

  4. Differing effects of water fugacity deformation of quartzites and milky quartz single crystals

    NASA Astrophysics Data System (ADS)

    Holyoke, C. W.; Kronenberg, A. K.

    2010-12-01

    Previous studies of quartzite deformation by dislocation creep have documented a strong dependence of mechanical properties on pressure, which has been interpreted as a relationship between strain rate and water fugacity (Kronenberg and Tullis, 1984; Kohlstedt et al., 1995; Chernak et al. 2009). However, natural milky quartz single crystals deformed by basal slip can be water-weakened over a wide range of pressure (and water fugacities), with strengths that appear to depend on total water content at a fixed water fugacity. The difference of behavior between these two is perplexing since infrared spectra collected from quartzites and milky quartz single crystals indicate that they have the same forms of intragranular water and microstructures indicate the same slip system is activated. The only difference between these materials is that quartzites include populations of grains of all orientations, separated by grain boundaries. In order to resolve this discrepancy we have performed deformation experiments on a natural quartzite (Black Hills quartzite) and natural milky quartz single crystals oriented for easy slip on the basal slip system at identical conditions (800°C, strain rate = 10-6/s) with no added water. During each experiment cores of each material, which have a fixed water content, were subjected to pressure stepping; an initial deformation step was performed at 1.5 GPa, then the sample was unloaded and one or more deformation steps were performed at lower pressures (as low as 0.6 GPa) prior to returning to 1.5 GPa for a final deformation step. The strength of quartzite increases dramatically at lower pressure and lower water fugacity, but strength decreases again returning to high pressure during the final deformation step. The strength of milky quartz single crystals increases as well, but by far less than observed for quartzites. The water fugacity exponents (m) of the quartzite and single crystals are 1.9 and 0.8, respectively, (assuming power

  5. FORTRAN programs for generating fluid inclusion isochores and fugacity coefficients for the system H 2O-CO 2-NaCl at high pressures and temperatures

    NASA Astrophysics Data System (ADS)

    Bowers, Teresa Suter; Helgeson, Harold C.

    Program DENFIND permits calculation of pressures and temperatures corresponding to isochores for H 2O-CO 2-NaCl fluids which can be used to generate pressure corrections of fluid inclusion homogenization temperatures. Program FUGCO facilitates calculation of fugacity coefficients in the system H 2O-CO 2-NaCl as a function of pressure, temperature and fluid composition. Both programs employ a modified Redlich-Kwong equation of state for the ternary system (Bowers and Helgeson, 1983a), which is applicable to fluids containing up to 35 wt. % NaCl (relative to H 2O + NaCl) at pressures above 500 bars and temperature from 350 to 600°C.

  6. 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.

  7. Theoretical calculation of oxygen equilibrium isotope fractionation factors involving various NOy molecules, radOH, and H2O and its implications for isotope variations in atmospheric nitrate

    NASA Astrophysics Data System (ADS)

    Walters, Wendell W.; Michalski, Greg

    2016-10-01

    The oxygen stable isotope composition (δ18O) of nitrogen oxides [NOx = nitric oxide (NO) + nitrogen dioxide (NO2)] and their oxidation products (NOy = NOx + nitric acid (HNO3) + particulate nitrate (p-NO3-) + nitrate radical (NO3) + dinitrogen pentoxide (N2O5) + nitrous acid (HONO) + …) have been shown to be a useful tool for inferring the proportion of NOx that is oxidized by ozone (O3). However, isotopic fractionation processes may have an influence on δ18O of various NOy molecules and other atmospheric O-bearing molecules pertinent to NOx oxidation chemistry. Here we have evaluated the impacts of O isotopic exchange involving NOy molecules, the hydroxyl radical (radOH), and water (H2O) using reduced partition function ratios (xβ) calculated by hybrid density functional theory. Assuming atmospheric isotopic equilibrium is achieved between NO and NO2 during the daytime, and NO2, NO3, and N2O5 during the nighttime, δ18O-δ15N compositions were predicted for the major atmospheric nitrate formation pathways using our calculated exchange fractionation factors and isotopic mass-balance. Our equilibrium model predicts that various atmospheric nitrate formation pathways, including NO2 + radOH → HNO3, N2O5 + H2O + surface → 2HNO3, and NO3 + R → HNO3 + Rrad will yield distinctive δ18O-δ15N compositions. Our calculated δ18O-δ15N compositions match well with previous atmospheric nitrate measurements, and will potentially help better understand the role oxidation chemistry plays on the N and O isotopic composition of atmospheric nitrate.

  8. Hydrogen component fugacity coefficients in binary mixtures with ethane: Pressure dependence

    NASA Astrophysics Data System (ADS)

    Bruno, T. J.; Schroeder, J. A.; Outcalt, S. L.

    1990-09-01

    The fugacity coefficients of hydrogen in binary mixtures with ethane were measured. Data were taken using an experimental chamber which is divided into two regions by a semipermeable membrane through which hydrogen, but not ethane, can penetrate. The measurement of the gas pressures inside and outside the membrane gives the hydrogen component fugacity at a given temperature, binary mixture mole fraction, and mixture pressure. In this paper, results are reported at mixture pressures of 5.25, 6.97, 10.21, and 13.47 MPa. In each case, the temperature of the mixture was maintained at an average value of 130°C (403.15 K). The general qualitative features of the data are discussed, and comparisons are made with predictions obtained from the Redlich-Kwong and Peng-Robinson equations of state.

  9. Hydrogen-component fugacity coefficients in binary mixtures with isobutane: temperature dependence

    NASA Astrophysics Data System (ADS)

    Bruno, T. J.; Outcalt, S. L.

    1990-01-01

    The fugacity coefficients of hydrogen in binary mixtures with isobutane were measured using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane through which hydrogen, but not isobutane, can penetrate. Measurement of the gas pressures inside and outside the membrane allow a direct measurement of the hydrogen component fugacity at a given temperature, binary mixture mole fraction, and mixture pressure. In this paper, results are reported at 120, 140, 160, and 180°C. In each case, the total pressure of the mixture was maintained at an average value of 3.40 MPa. The general qualitative features of the data are discussed, and comparisions are made with predictions obtained from the Redlich-Kwong and the Peng-Robinson equations of state.

  10. Theoretical modelling of biomolecular systems I. Large-scale QM/MM calculations of hydrogen-bonding networks of the oxygen evolving complex of photosystem II

    NASA Astrophysics Data System (ADS)

    Shoji, Mitsuo; Isobe, Hiroshi; Yamanaka, Shusuke; Umena, Yasufumi; Kawakami, Keisuke; Kamiya, Nobuo; Shen, Jian-Ren; Nakajima, Takahito; Yamaguchi, Kizashi

    2015-02-01

    Quantum mechanical (QM)/molecular mechanics (MM) calculations by the use of a large-scale QM model (QM Model V) have been performed to elucidate hydrogen-bonding networks and proton wires for proton release pathways (PRP) of water oxidation reaction in the oxygen evolving complex (OEC) of photosystem II (PSII). Full geometry optimisations of PRP by the QM/MM model have been carried out starting from the geometry of heavy atoms determined by the recent high-resolution X-ray diffraction (XRD) experiment of PSII refined to 1.9 Å resolution. Computational results by the QM/MM calculations have elucidated the hydrogen-bonding O...O(N) and O...H distances and O(N)-H...O angles in PRP, together with the Cl-O(N) and Cl...H distances and O(N)-H...Cl angles for chloride anions. The optimised hydrogen-bonding networks are well consistent with the XRD results and available experiments such as extended X-ray absorption fine structure, showing the reliability of channel structures of OEC of PSII revealed by the XRD experiment. The QM/MM computations have elucidated possible roles of chloride anions in the OEC of PSII. The QM/MM computational results have provided useful information for understanding and explanation of accumulated mutation experiments of key amino acid residues in the OEC of PSII. Implications of the present results are discussed in relation to three steps for theoretical modelling of water oxidation in the OEC of PSII and bio-inspired working hypotheses for developments of artificial water oxidation systems by use of 3d transition-metal complexes.

  11. Calculating specific denitrification rates in pre-denitrification by assessing the influence of dissolved oxygen, sludge loading and mixed-liquor recycle.

    PubMed

    Raboni, Massimo; Torretta, Vincenzo; Viotti, Paolo; Urbini, Giordano

    2014-01-01

    This article presents the results of an experimental study on the correlation among the specific denitrification rate (SDNR), the dissolved oxygen concentration (DO), the F:M ratio (F:M) and the mixed-liquor (ML) recycle in the pre-denitrification reactors fed by domestic sewage. The experimental curves reveal a 28.8-32.0% reduction in the SDNR at 20 degrees C (SDNR(20 degrees C)) with DO equal to 0.1 mgO2 L(-1) and F:M in the range 0.2-0.4 kgBOD5 kgMLVSS(-1) d(-1). The SDNR reduction increases to 50.0-55.9% with DO = 0.3 mgO2 L(-1). A mathematical correlation of these results and an equation for calculating SDNR(20 degrees C) as function of the F:M as well as the average DO and BOD5 in the total flow rate fed in the denitrification stage are proposed. The conducted experience gives useful suggestions for practical usage, in particular regarding the denitrification reactor design, and represents a good starting point for future applications with the aim to optimize the biological process in domestic sewage treatment plants.

  12. FeO2 and FeOOH under deep lower-mantle conditions and Earth's oxygen-hydrogen cycles.

    PubMed

    Hu, Qingyang; Kim, Duck Young; Yang, Wenge; Yang, Liuxiang; Meng, Yue; Zhang, Li; Mao, Ho-Kwang

    2016-06-09

    The distribution, accumulation and circulation of oxygen and hydrogen in Earth's interior dictate the geochemical evolution of the hydrosphere, atmosphere and biosphere. The oxygen-rich atmosphere and iron-rich core represent two end-members of the oxygen-iron (O-Fe) system, overlapping with the entire pressure-temperature-composition range of the planet. The extreme pressure and temperature conditions of the deep interior alter the oxidation states, spin states and phase stabilities of iron oxides, creating new stoichiometries, such as Fe4O5 (ref. 5) and Fe5O6 (ref. 6). Such interactions between O and Fe dictate Earth's formation, the separation of the core and mantle, and the evolution of the atmosphere. Iron, in its multiple oxidation states, controls the oxygen fugacity and oxygen budget, with hydrogen having a key role in the reaction of Fe and O (causing iron to rust in humid air). Here we use first-principles calculations and experiments to identify a highly stable, pyrite-structured iron oxide (FeO2) at 76 gigapascals and 1,800 kelvin that holds an excessive amount of oxygen. We show that the mineral goethite, FeOOH, which exists ubiquitously as 'rust' and is concentrated in bog iron ore, decomposes under the deep lower-mantle conditions to form FeO2 and release H2. The reaction could cause accumulation of the heavy FeO2-bearing patches in the deep lower mantle, upward migration of hydrogen, and separation of the oxygen and hydrogen cycles. This process provides an alternative interpretation for the origin of seismic and geochemical anomalies in the deep lower mantle, as well as a sporadic O2 source for the Great Oxidation Event over two billion years ago that created the present oxygen-rich atmosphere.

  13. Scaling of Gene Expression with Transcription-Factor Fugacity

    PubMed Central

    Weinert, Franz M.; Brewster, Robert C.; Rydenfelt, Mattias; Phillips, Rob; Kegel, Willem K.

    2015-01-01

    The proteins associated with gene regulation are often shared between multiple pathways simultaneously. By way of contrast, models in regulatory biology often assume these pathways act independently. We demonstrate a framework for calculating the change in gene expression for the interacting case by decoupling repressor occupancy across the cell from the gene of interest by way of a chemical potential. The details of the interacting regulatory architecture are encompassed in an effective concentration, and thus, a single scaling function describes a collection of gene expression data from diverse regulatory situations and collapses it onto a single master curve. PMID:25554908

  14. Scaling of gene expression with transcription-factor fugacity.

    PubMed

    Weinert, Franz M; Brewster, Robert C; Rydenfelt, Mattias; Phillips, Rob; Kegel, Willem K

    2014-12-19

    The proteins associated with gene regulation are often shared between multiple pathways simultaneously. By way of contrast, models in regulatory biology often assume these pathways act independently. We demonstrate a framework for calculating the change in gene expression for the interacting case by decoupling repressor occupancy across the cell from the gene of interest by way of a chemical potential. The details of the interacting regulatory architecture are encompassed in an effective concentration, and thus, a single scaling function describes a collection of gene expression data from diverse regulatory situations and collapses it onto a single master curve.

  15. Fugacity gradients of hydrophobic organics across the air-water interface measured with a novel passive sampler.

    PubMed

    Wu, Chen-Chou; Yao, Yao; Bao, Lian-Jun; Wu, Feng-Chang; Wong, Charles S; Tao, Shu; Zeng, Eddy Y

    2016-11-01

    Mass transfer of hydrophobic organic contaminants (HOCs) across the air-water interface is an important geochemical process controlling the fate and transport of HOCs at the regional and global scales. However, few studies have characterized concentration or fugacity profiles of HOCs near both sides of the air-water interface, which is the driving force for the inter-compartmental mass transfer of HOCs. Herein, we introduce a novel passive sampling device which is capable of measuring concentration (and therefore fugacity) gradients of HOCs across the air-water interface. Laboratory studies indicated that the escaping fugacity values of polycyclic aromatic hydrocarbons (PAHs) from water to air were negatively correlated to their volatilization half-lives. Results for field deployment were consistent between the passive sampler and an active method, i.e., a combination of grab sampling and liquid-liquid extraction. In general, the fugacity profiles of detected PAHs were indicative of an accumulation mechanism in the surface microlayer of the study regions (Haizhu Lake and Hailing Bay of Guangdong Province, China), while p,p'-DDD tended to volatilize from water to the atmosphere in Hailing Bay. Furthermore, the fugacity profiles of the target analytes increased towards the air-water interface, reflecting the complexity of environmental behavior of the target analytes near the air-water interface. Overall, the passive sampling device provides a novel means to better characterize the air-water diffusive transfer of HOCs, facilitating the understanding of the global cycling of HOCs.

  16. Structure of the oxygen-evolving complex of photosystem II: information on the S(2) state through quantum chemical calculation of its magnetic properties.

    PubMed

    Pantazis, Dimitrios A; Orio, Maylis; Petrenko, Taras; Zein, Samir; Lubitz, Wolfgang; Messinger, Johannes; Neese, Frank

    2009-08-21

    Twelve structural models for the S(2) state of the oxygen-evolving complex (OEC) of photosystem II are evaluated in terms of their magnetic properties. The set includes ten models based on the 'fused twist' core topology derived by polarized EXAFS spectra and two related models proposed in recent mechanistic investigations. Optimized geometries and spin population analyses suggest that Mn(iii), which is most often identified with the manganese ion at site D, is always associated with a penta-coordinate environment, unless a chloride is directly ligated to the metal. Exchange coupling constants were determined by broken-symmetry density functional theory calculations and the complete spectrum of magnetic sublevels was obtained by direct diagonalization of the Heisenberg Hamiltonian. Seven models display a doublet ground state and are considered spectroscopic models for the ground state corresponding to the multiline signal (MLS) of the S(2) state of the OEC, whereas the remaining five models display a sextet ground state and could be related to the g = 4.1 signal of the S(2) state. It is found that the sign of the exchange coupling constant between the Mn centres at positions A and B of the cluster is directly related to the ground state multiplicity, implying that interconversion between the doublet and sextet can be induced by only small structural perturbations. The recently proposed quantum chemical method for the calculation of (55)Mn hyperfine coupling constants is subsequently applied to the S(2) MLS state models and the quantities that enter into the individual steps of the procedure (site-spin expectation values, intrinsic site isotropic hyperfine parameters and projected (55)Mn isotropic hyperfine constants) are analyzed and discussed in detail with respect to the structural and electronic features of each model. The current approach performs promisingly. It reacts sensitively to structural distortions and hence may be able to distinguish between different

  17. Using fugacity to predict volatile emissions from layered materials with a clay/polymer diffusion barrier

    NASA Astrophysics Data System (ADS)

    Yuan, Huali; Little, John C.; Marand, Eva; Liu, Zhe

    Structural insulated panels (SIPs) have significant environmental and energy advantages. However, the tight structure that results may cause degraded indoor air quality and the potential release of volatile organic compounds (VOCs) from these layered materials must be considered. A physically based model for predicting VOC emissions from multi-layer materials is described. Fugacity is used to eliminate the concentration discontinuities at the interface between layers. This avoids an obstacle associated with numerically simulating mass transfer in composite materials. The numerical model is verified for a double-layer system by comparing predicted concentrations to those obtained with a previously published analytical model. In addition, hexanal emissions from multi-layer SIPs are simulated to demonstrate the usefulness of the fugacity approach. Finally, the multi-layer model is used to investigate the impact that clay/polyurethane nanocomposite diffusion barriers can have on VOC emissions. Indoor gas-phase concentrations can be greatly reduced with a barrier layer on the surface, thereby minimizing the environmental impact of SIPs.

  18. FeO2 and FeOOH under deep lower-mantle conditions and Earth’s oxygen-hydrogen cycles

    NASA Astrophysics Data System (ADS)

    Hu, Qingyang; Kim, Duck Young; Yang, Wenge; Yang, Liuxiang; Meng, Yue; Zhang, Li; Mao, Ho-Kwang

    2016-06-01

    The distribution, accumulation and circulation of oxygen and hydrogen in Earth’s interior dictate the geochemical evolution of the hydrosphere, atmosphere and biosphere. The oxygen-rich atmosphere and iron-rich core represent two end-members of the oxygen-iron (O-Fe) system, overlapping with the entire pressure-temperature-composition range of the planet. The extreme pressure and temperature conditions of the deep interior alter the oxidation states, spin states and phase stabilities of iron oxides, creating new stoichiometries, such as Fe4O5 (ref. 5) and Fe5O6 (ref. 6). Such interactions between O and Fe dictate Earth’s formation, the separation of the core and mantle, and the evolution of the atmosphere. Iron, in its multiple oxidation states, controls the oxygen fugacity and oxygen budget, with hydrogen having a key role in the reaction of Fe and O (causing iron to rust in humid air). Here we use first-principles calculations and experiments to identify a highly stable, pyrite-structured iron oxide (FeO2) at 76 gigapascals and 1,800 kelvin that holds an excessive amount of oxygen. We show that the mineral goethite, FeOOH, which exists ubiquitously as ‘rust’ and is concentrated in bog iron ore, decomposes under the deep lower-mantle conditions to form FeO2 and release H2. The reaction could cause accumulation of the heavy FeO2-bearing patches in the deep lower mantle, upward migration of hydrogen, and separation of the oxygen and hydrogen cycles. This process provides an alternative interpretation for the origin of seismic and geochemical anomalies in the deep lower mantle, as well as a sporadic O2 source for the Great Oxidation Event over two billion years ago that created the present oxygen-rich atmosphere.

  19. Calculation of arrangement of oxygen ions and vacancies in double perovskite GdBaCo2O(5+δ) by first-principles DFT with Monte Carlo simulations.

    PubMed

    Shiiba, Hiromasa; Nakayama, Masanobu; Kasuga, Toshihiro; Grimes, Robin W; Kilner, John A

    2013-07-07

    The configurations of oxygen ions and vacancies at various oxygen stoichiometries and temperatures in double perovskite oxides (GdBaCo2O(5+δ), 0 ≤ δ ≤ 1) have been determined by density functional theory (DFT) combined with Monte Carlo (MC) simulations. The MC simulations confirmed the existence of a superstructure at δ = 0.5, showing alternating linear ordering of oxygen ions and vacancies along the b-axis in the GdO layer. This structure is identical to that reported experimentally. Increasing the temperature up to 1200 K induces a phase transition manifested in the breaking of the oxygen/vacancy arrangement at around δ = 0.5. In the high-temperature phase, vacancies are distributed in the GdO and CoO2 layers, whereas there are no vacancies in the BaO layer. In addition, the characteristic linear arrangement is partly preserved even in the disordered high-temperature phase. Consequently, oxygen ions can migrate between the GdO and CoO2 layers, as reported in previous classical molecular dynamics simulation studies.

  20. Cordierite-garnet-H2O equilibrium: A geological thermometer, barometer and water fugacity indicator

    NASA Astrophysics Data System (ADS)

    Martignole, Jacques; Sisi, Jean-Charles

    1981-03-01

    area of Mg-cordierite stability allowed by the hydration data forP_{H_2 O} = P_{total} . The present model indicates greater stabilization of cordierite by H2O than the model of Newton and Wood (1979) and the calculated curve for metastable breakdown of hydrous MgCd is consistent with experimental data on cordierite breakdown atP_{H_2 O} = P_{total} . Mg/(Mg+Fe) isopleths have been derived for cordierites of varying nH2O in the SiO2-Al2O3-MgO-FeO-H2O system using the additional assumptions that (Fe, Mg) cordierite and (Fe, Mg) garnet behave as ideal solutions, and that typical values of the distribution coefficient of Fe and Mg between coexisting garnet and cordierite observed in natural parageneses can be applied to the calculations. The calculated stable breakdown curve of Fe-cordierite under conditions ofP_{H_2 O} = P_{total} to almandine, sillimanite, quartz and vapor has a positive slope ( dP/dT) apparently in contrast to the experimental negative slope. This may be explained by hydration kinetics, which could have allowed systematic breakdown of cordierites of metastable hydration states in the experiments. The bivariant Cd-Ga fields calibrated from the present model are, potentially, good petrogenetic indicators, as, given the iron-magnesium ratio of garnet and cordierite and the hydration number of cordierite, the temperature, pressure and water fugacity are uniquely determined. As this geothermobarometer is in part based on the water content of cordierite, it can be used only if there is some assurance that the actual hydration is inherited from high-grade metamorphic conditions. Such conditions could be realised if the slope of unloading-cooling retrograde metamorphism is more or less parallel to a cordierite isohydron.

  1. Utilizing polymer-coated vials to illustrate the fugacity and bioavailability of chlorinated pesticide residues in contaminated soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fugacity and bioavailability concepts can be challenging topics to communicate effectively in the timeframe of an academic laboratory course setting. In this experiment, students observe partitioning of the residues over time into an artificial biological matrix. The three compounds utilized are o...

  2. CO oxidation on PdO catalysts with perfect and defective rutile-TiO2 as supports: Elucidating the role of oxygen vacancy in support by DFT calculations

    NASA Astrophysics Data System (ADS)

    Li, Xiao; Sun, Xiongfei; Xu, Xianglan; Liu, Wenming; Peng, Honggen; Fang, Xiuzhong; Wang, Hongming; Wang, Xiang

    2017-04-01

    To explore metal oxide-oxide support interactions and their effects, the mechanism of CO oxidation on PdO catalysts with rutile TiO2 or TiO2-x (TiO2 with a bridging oxygen vacancy) as the support, was studied by density functional theory calculations, compared with that on pure PdO surface. For TiO2 as the support, support effect leads to the change of the preferential CO adsorption sites from the coordinatively unsaturated Pd (Pdcus) site on pure PdO surface to the bridging site of coordinatively unsaturated Pd and O atoms (Pdcus and Ocus), thus altering the reaction pathway of CO oxidation, whereas the support effect has little influence on the energy barrier. However, for TiO2-x as the support, the presence of the oxygen vacancy leads to the energy barrier remarkably decreased compared with that on pure or TiO2-supported PdO surface. The change of Bader charges indicates the oxygen vacancy in the support can tune the oxidizability of PdO surface active oxygen Ocus, thus adjusting the CO adsorption strength at the bridging site of Pdcus and Ocus to be favorable for the extraction process of Ocus. Tuning oxygen vacancies in supports can be used as a new perspective to design improved supported oxide catalysts.

  3. Fugacity based modeling for pollutant fate and transport during floods. Preliminary results

    NASA Astrophysics Data System (ADS)

    Deda, M.; Fiorini, M.; Massabo, M.; Rudari, R.

    2010-09-01

    Fugacity based modeling for pollutant fate and transport during floods. Preliminary results Miranda Deda, Mattia Fiorini, Marco Massabò, Roberto Rudari One of the concerns that arises during floods is whether the wide-spreading of chemical contamination is associated with the flooding. Many potential sources of toxics releases during floods exists in cities or rural area; hydrocarbons fuel storage system, distribution facilities, commercial chemical storage, sewerage system are only few examples. When inundated homes and vehicles can also be source of toxics contaminants such as gasoline/diesel, detergents and sewage. Hazardous substances released into the environment are transported and dispersed in complex environmental systems that include air, plant, soil, water and sediment. Effective environmental models demand holistic modelling of the transport and transformation of the materials in the multimedia arena. Among these models, fugacity-based models are distribution based models incorporating all environmental compartments and are based on steady-state fluxes of pollutants across compartment interfaces (Mackay "Multimedia Environmental Models" 2001). They satisfy the primary objective of environmental chemistry which is to forecast the concentrations of pollutants in the environments with respect to space and time variables. Multimedia fugacity based-models has been used to assess contaminant distribution at very different spatial and temporal scales. The applications range from contaminant leaching to groundwater, runoff to surface water, partitioning in lakes and streams, distribution at regional and even global scale. We developped a two-dimensional fugacity based model for fate and transport of chemicals during floods. The model has three modules: the first module estimates toxins emission rates during floods; the second modules is the hydrodynamic model that simulates the water flood and the third module simulate the dynamic distribution of chemicals in

  4. Electrostatic modes in dense dusty plasmas with high fugacity: Numerical results

    NASA Astrophysics Data System (ADS)

    Rao, N. N.

    2000-08-01

    The existence of ultra low-frequency wave modes in dusty plasmas has been investigated over a wide range of dust fugacity [defined by f≡4πnd0λD2R, where nd0 is the dust number density, λD is the plasma Debye length, and R is the grain size (radius)] and the grain charging frequency (ω1) by numerically solving the dispersion relation obtained from the kinetic (Vlasov) theory. A detailed comparison between the numerical and the analytical results applicable for the tenuous (low fugacity, f≪1), the dilute (medium fugacity, f˜1), and the dense (high fugacity, f≫1) regimes has been carried out. In the long wavelength limit and for frequencies ω≪ω1, the dispersion curves obtained from the numerical solutions of the real as well as the complex (kinetic) dispersion relations agree, both qualitatively and quantitatively, with the analytical expressions derived from the fluid and the kinetic theories, and are thus identified with the ultra low-frequency electrostatic dust modes, namely, the dust-acoustic wave (DAW), the dust charge-density wave (DCDW) and the dust-Coulomb wave (DCW) discussed earlier [N. N. Rao, Phys. Plasmas 6, 4414 (1999); 7, 795 (2000)]. In particular, the analytical scaling between the phase speeds of the DCWs and the DAWs predicted from theoretical considerations, namely, (ω/k)DCW=(ω/k)DAW/√fδ (where δ is the ratio of the charging frequencies) is in excellent agreement with the numerical results. A simple physical picture of the DCWs has been proposed by defining an effective pressure called "Coulomb pressure" as PC≡nd0qd02/R, where qd0 is the grain surface charge. Accordingly, the DCW dispersion relation is given, in the lowest order, by (ω/k)DCW=√PC/ρdδ , where ρd≡nd0md is the dust mass density. Thus, the DCWs which are driven by the Coulomb pressure can be considered as the electrostatic analogue of the hydromagnetic (Alfvén or magnetoacoustic) waves which are driven by the magnetic field pressure. For the frequency

  5. Deriving Algorithms for the Remote Sensing of Carbon Dioxide Fugacity at the Ocean Surface

    NASA Astrophysics Data System (ADS)

    Minnett, P. J.; Wickramaratna, K.; Kubat, M.

    2010-12-01

    As concentrations of carbon dioxide in the atmosphere continue to rise, the capacity of the ocean to act as a carbon dioxide sink is of critical importance as it is the major sink of anthropogenic carbon dioxide. Uncertainties in our ability to quantify the role of the oceans in the carbon cycle, especially in computing the gas fluxes between atmosphere and ocean on global scales, leads directly to uncertainty in predicting the response of the of the climate system to increasing levels of carbon dioxide in the atmosphere. Here we report on a study to improve the accuracy of the retrievals of surface fugacity from earth observation satellites. A large data set of in situ measurements from equipment on the Royal Caribbean Cruise Lines ship Explorer of the Seas in the Caribbean Sea and western tropical Atlantic Ocean the relationship between the carbon dioxide concentration and variables measurable from space is explored using advanced computational techniques to improve on prior results derived by linear regression. Using natural selection as a conceptual model, the Genetic Algorithm approach maintains a population of “tentative” solutions that are subjected to “survival of the fittest” tests and to operators that implement mutation and recombination (mutual exchange of the “genetic information”). In our implementation, each specimen in the population represents one formula, expressed by a tree-like data structure. The fitness function that quantifies the individual's survival chances is defined as the mean square error scored by the given formula on the training data. We demonstrate in this case study that not only can the accuracy of satellite retrievals of surface fugacity of carbon dioxide be improved by using algorithms based on the information content of the data sets, but also the regions in which individual algorithms are applicable can also be determined. These regions align with the underlying dynamical oceanographic features. This approach can

  6. Lunar and Planetary Science XXXV: Special Session: Oxygen in the Solar System, II

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The Special Session: Oxygen in the Solar System, II, included the following reports:Evolution of Oxygen Isotopes in the Solar Nebula; Disequilibrium Melting of Refractory Inclusions: A Mechanism for High-Temperature Oxygen; Isotope Exchange in the Solar Nebula; Oxygen Isotopic Compositions of the Al-rich Chondrules in the CR Carbonaceous Chondrites: Evidence for a Genetic Link to Ca-Al-rich Inclusions and for Oxygen Isotope Exchange During Chondrule Melting; Nebular Formation of Fayalitic Olivine: Ineffectiveness of Dust Enrichment; Water in Terrestrial Planets: Always an Oxidant?; Oxygen Barometry of Basaltic Glasses Based on Vanadium Valence Determination Using Synchrotron MicroXANES; A New Oxygen Barometer for Solar System Basaltic Glasses Based on Vanadium Valence; The Relationship Between Clinopyroxene Fe3+ Content and Oxygen Fugacity ; and Olivine-Silicate Melt Partitioning of Iridium.

  7. Applying the Ce-in-zircon oxygen geobarometer to diverse silicic magmatic systems

    NASA Astrophysics Data System (ADS)

    Claiborne, L. L.; Miller, C. F.

    2012-12-01

    Zircon provides information on age, temperature, and composition of the magma from which it grew. In systems such as Mount St. Helens, where zircon is not coeval with the rest of the crystal cargo, it provides the only accessible record of the extended history of the magmatic system, including cycles of intrusion, crystallization and rejuvenation beneath an active volcano (Claiborne et al., 2010). The rare earth elements, which are present in measureable quantities in zircon, provide information about the composition of the magma from which zircon grew. Unique among the generally trivalent rare earth elements, cerium can exist as either trivalent or tetravalent, depending on the oxidation state of the magma. The tetravalent ion is highly compatible in zircon, in the site that usually hosts tetravalent zirconium, and so the amount of Cerium in zircon relative (relative to what would be expected of trivalent Ce) depends the oxidation state of the magma from which it grew. Trail et al. (2011) proposed a calibration based on experimental data that uses the Ce anomaly in zircon as a direct proxy for magma oxidation (fugacity), describing the relationship between Ce in zircon and magma oxygen fugacity as ln(Ce/Ce*)D = (0.1156±0.0050)xln(fO2)+(13860±708)/T-(6.125±0.484). For systems like Mount St. Helens, where the major minerals record only events in the hundreds to thousands of years leading to eruption, (including the Fe-Ti oxides traditionally relied upon for records of oxidation state of the magmas), this presents a novel approach for understanding more extended histories of oxidation of magmas in the tens and hundreds of thousands of years of magmatism at a volcanic center. This calibration also promises to help us better constrain conditions of crystallization in intrusive portions of volcanic systems, as well as plutonic bodes. We apply this new oxygen geobarometer to natural volcanic and plutonic zircons from a variety of tectonic settings, and compare to

  8. Calculation of water-bearing primary basalt and estimation of source mantle conditions beneath arcs: PRIMACALC2 model for WINDOWS

    NASA Astrophysics Data System (ADS)

    Kimura, Jun-Ichi; Ariskin, Alexey A.

    2014-04-01

    present a new method for estimating the composition of water-bearing primary arc basalt and its source mantle conditions. The PRIMACALC2 model uses a thermodynamic fractional crystallization model COMAGMAT3.72 and runs with an Excel macro to examine the mantle equilibrium and trace element calculations of a primary basalt. COMAGMAT3.72 calculates magma fractionation in 0-10 kb at various compositions, pressure, oxygen fugacity, and water content, but is only applicable for forward calculations. PRIMACALC2 first calculates the provisional composition of a primary basalt from an observed magma. The basalt composition is then calculated by COMAGMAT3.72 for crystallization. Differences in elemental concentrations between observed and the closest-match calculated magmas are then adjusted in the primary basalt. Further iteration continues until the calculated magma composition converges with the observed magma, resulting in the primary basalt composition. Once the fitting is satisfied, back calculations of trace elements are made using stepwise addition of fractionated minerals. Mantle equilibrium of the primary basalt is tested using the Fo-NiO relationship of olivine in equilibrium with the primary basalt, and thus with the source mantle. Source mantle pressure, temperature, and degree of melting are estimated using petrogenetic grids based on experimental data obtained in anhydrous systems. Mantle melting temperature in a hydrous system is computed by adjusting T with a parameterization for a water-bearing system. PRIMACALC2 can be used either in dry or water-bearing arc magmas and is also applicable to mid-ocean ridge basalts and nonalkalic ocean island basalts.

  9. Precipitates/Salts Model Sensitivity Calculation

    SciTech Connect

    P. Mariner

    2001-12-20

    The objective and scope of this calculation is to assist Performance Assessment Operations and the Engineered Barrier System (EBS) Department in modeling the geochemical effects of evaporation on potential seepage waters within a potential repository drift. This work is developed and documented using procedure AP-3.12Q, ''Calculations'', in support of ''Technical Work Plan For Engineered Barrier System Department Modeling and Testing FY 02 Work Activities'' (BSC 2001a). The specific objective of this calculation is to examine the sensitivity and uncertainties of the Precipitates/Salts model. The Precipitates/Salts model is documented in an Analysis/Model Report (AMR), ''In-Drift Precipitates/Salts Analysis'' (BSC 2001b). The calculation in the current document examines the effects of starting water composition, mineral suppressions, and the fugacity of carbon dioxide (CO{sub 2}) on the chemical evolution of water in the drift.

  10. 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 ...

  11. Pressure, temperature and oxygen fugacity conditions of calc-alkaline granitoids, Eastern Desert of Egypt, and tectonic implications

    NASA Astrophysics Data System (ADS)

    Helmy, H. M.; Ahmed, A. F.; El Mahallawi, M. M.; Ali, S. M.

    2004-02-01

    Five calc-alkaline plutons; Um Tagher, Abu Zawil, Um Gidri, Um Anab and El Ghuzah, in the northern Eastern Desert of Egypt were subjected to petrographic and mineralogical investigations. They are composed of varying proportions of quartz + plagioclase + potash feldspar + biotite + hornblende ± epidote ± calcite + titanite + magnetite + apatite and zircon. Electron microprobe analyses of coexisting hornblende and plagioclase (hornblende-plagioclase thermometry), Al content in hornblende (aluminum-in-hornblende barometry) and the assemblage titanite-magnetite-quartz were used to constrain the P, T and fO 2 during the crystallization of the parent magmas in the different plutons. The plutons crystallized under varying pressures (5.4-2.1 kbar) and wide range of temperature (785-588 °C) from highly oxidized magmas (log fO 2 -21 to -13). The pressure data discriminate three categories of granitoid emplaced at different crustal levels: (a) upper crust granitoids (e.g., El Ghuzah, and Abu Zawil) emplaced at depths <9 km; (b) intermediate crust granitoids (e.g., Um Gidri and Um Anab) emplaced at depths <13 km; and (c) lower crust granitoids (e.g., Um Tagher) emplaced at depths <21 km. The depths of emplacement seem to increase from northwest to southeast. It is likely that the magmas forming these plutons were generated at different depths; they were similar in composition but varied substantially in their water and volatile contents. High water and volatile contents allowed the magma of some plutons to reach shallower crustal levels without complete solidification. Although these complexes were crystallized at different depths, they were later uplifted to the same level by upward faulting.

  12. Explosive volcanism and the graphite-oxygen fugacity buffer on the parent asteroid(s) of the ureilite meteorites

    NASA Technical Reports Server (NTRS)

    Warren, Paul H.; Kallemeyn, Gregory W.

    1992-01-01

    A new model of the production of the uniformly low plagioclase and Al contents of ureilites is proposed. It is argued that those contents are consequences of widespread explosive volcanism during the evolution of the parent asteroid(s). It is noted that the great abundance of graphite on the ureilite asteroid(s) made them ideal sites for explosive volcanism driven by oxidation of graphite in partial melts ascending within the asteroid(s).

  13. Methane origin and oxygen-fugacity evolution of the Baogutu reduced porphyry Cu deposit in the West Junggar terrain, China

    NASA Astrophysics Data System (ADS)

    Shen, Ping; Pan, HongDi

    2015-12-01

    Most porphyry copper deposits worldwide contain magnetite, hematite, and anhydrite in equilibrium with hypogene copper-iron sulfides (chalcopyrite, bornite) and have fluid inclusions with CO2 >> CH4 that are indicative of high fO2. In contrast, the Baogutu porphyry Cu deposit in the West Junggar terrain (Xinjiang, China) lacks hematite and anhydrite, contains abundant pyrrhotite and ilmenite in equilibrium with copper-iron sulfides (chalcopyrite), and has fluid inclusions with CH4 >> CO2 that are indicative of low fO2. The mineralized intrusive phases at Baogutu include the main-stage diorite stock and minor late-stage diorite porphyry dikes. The main-stage stock underwent fractional crystallization and country-rock assimilation-contamination, and consists of dominant diorite and minor gabbro and tonalite porphyry. The country rocks contain organic carbons (0.21-0.79 wt.%). The δ13CvPDB values of the whole rocks (-23.1 to -25.8 ‰) in the wall rocks suggest a sedimentary organic carbon source. The δ13CvPDB values of CH4 (-28.2 to -36.0 ‰) and CO2 (-6.8 to -20.0 ‰) in fluid inclusions require an organic source of external carbon and equilibration of their Δ13CCO2-CH4 values (8.2-25.0 ‰) at elevated temperatures (294-830 °C) suggesting a significant contribution of thermogenic CH4. Mineral composition data on the main-stage intrusions, such as clinopyroxene, hornblende, biotite, magnetite, ilmenite, sphene, apatite, and pyrrhotite, suggest that the primary magma at Baogutu was oxidized and became reduced after emplacement by contamination with country rocks. Mineral compositions and fluid inclusion gas compositions suggest that the redox state of the system evolved from log fO2 > FMQ + 1 in the magma stage, to log fO2 < FMQ as a consequence of country rocks assimilation-contamination, to log fO2 > FMQ in the hydrothermal stage. Though oxidized magma was emplaced initially, assimilation-contamination of carbonaceous country rocks decreased its fO2 such that exsolved fluids contained abundant CH4 and deposited a reduced assemblage of minerals.

  14. Effect of Cooling Rate and Oxygen Fugacity on the Crystallization of the Queen Alexandra Range 94201 Martian Melt Composition

    NASA Technical Reports Server (NTRS)

    Koizumi, E.; Mikouchi, T.; McKay, G.; Schwandt, C.; Monkawa, A.; Miyamoto, M.

    2002-01-01

    Although many basaltic shergottites have been recently found in north African deserts, QUE94201 basaltic shergottite (QUE) is still important because of its particular mineralogical and petrological features. This meteorite is thought to represent its parent melt composition [1 -3] and to crystallize under most reduced condition in this group [1,4]. We performed experimental study by using the synthetic glass that has the same composition as the bulk of QUE. After homogenization for 48 hours at 1300 C, isothermal and cooling experiments were done under various conditions (e.g. temperature, cooling rates, and redox states). Our goals are (1) to verify that QUE really represents its parent melt composition, (2) to estimate a cooling rate of this meteorite, (3) to clarify the crystallization sequences of present minerals, and (4) to verity that this meteorite really crystallized under reduced condition.

  15. Chromium Oxidation State in Planetary Basalts: Oxygen Fugacity Indicator and Critical Variable for Cr-Spinel Stability

    NASA Technical Reports Server (NTRS)

    Bell, A. S.; Burger, P. V.; Le, Loan; Papike, J. J.; Jone, J.; Shearer, C. K.

    2014-01-01

    Cr is a ubiquitous and relatively abundant minor element in basaltic, planetary magmas. At the reduced oxidation states (

  16. The Oxidation State of Fe in Glasses from the Galapagos Archipelago: Variable Oxygen Fugacity as a Function of Mantle Source

    NASA Astrophysics Data System (ADS)

    Peterson, M. E.; Kelley, K. A.; Cottrell, E.; Saal, A. E.; Kurz, M. D.

    2015-12-01

    The oxidation state of the mantle plays an intrinsic role in the magmatic evolution of the Earth. Here we present new μ-XANES measurements of Fe3+/ΣFe ratios (a proxy for ƒO2) in a suite of submarine glasses from the Galapagos Archipelago. Using previously presented major, trace, and volatile elements and isotopic data for 4 groups of glass that come from distinct mantle sources (depleted upper mantle, 2 recycled, and a primitive mantle source) we show that Fe3+/ΣFe ratios vary both with the influence of shallow level processes and with variations in mantle source. Fe3+/ΣFe ratios increase with differentiation (i.e. decreasing MgO), but show a large variation at a given MgO. Progressive degassing of sulfur accompanies decreasing Fe3+/ΣFe ratios, while assimilation of hydrothermally altered crust (as indicated by increasing Sr/Sr*) is shown to increase Fe3+/ΣFe ratios. After taking these processes into account, there is still variability in the Fe3+/ΣFe ratios of the isotopically distinct sample suites studied, yielding a magmatic ƒO2 that ranges from ΔQFM = +0.16 to +0.74 (error < 0.5 log units) and showing that oxidation state varies as a function of mantle source composition in the Galapagos hotspot system. After correcting back to a common MgO content = 8.0 wt%, the trace element depleted group similar to MORB (ITD), and the group similar to Pinta (WD = high Th/La, Δ7/4, Δ8/4 ratios) show Fe3+/ΣFe ratios within the range of MORB (average ITD = 0.162 ± 0.003 and WD = 0.164 ± 0.006). Another trace element enriched group similar to Sierra Negra and Cerro Azul (ITE = enriched Sr and Pb isotopes) shows evidence of mixing between oxidized and reduced sources (ITE oxidized end-member = 0.177). This suggests that mantle sources in the Galapagos that are thought to contain recycled components (i.e., WD and ITE groups) have distinct oxidation states. The high 3He/4He Fernandina samples (HHe group) are shown to be the most oxidized (ave. 0.175 ± 0.006). With C/3He ratios an order of magnitude greater than MORB this suggests that the primitive mantle is a more carbonated and oxidized source than the depleted upper mantle.

  17. The Effects of Oxygen Fugacity on the Crystallization Sequence and Cr Partitioning of an Analog Y-98 Liquid

    NASA Technical Reports Server (NTRS)

    Bell, A. S.; Burger, P. V.; Le, Loan; Papike, J. J.; Jones, J.; Shearer, C. K.

    2013-01-01

    Interpreting the relationship between "enriched" olivine-phyric shergottites (e.g. NWA 1068/1110) and the "enriched" pyroxene-plagioclase shergottites (e.g. Shergotty, Los Angeles) is problematic. Symes et al. [1] and Shearer et al. [2]) proposed that the basaltic magma that crystallized to produce olivine-phyric shergottite NWA 1068/1110 could produce pyroxene-plagioclase shergottites with additional fractional crystallization. However, additional observations indicate that the relationship among the enriched shergottites may be more complex [1-3]. For example, Herd [3] concluded that some portion of the olivine megacrysts in this meteorite was xenocrystic in origin, seemingly derived from more reduced basaltic liquids. This conclusion may imply that a variety of complex processes such as magma mixing, entrainment, and assimilation may play important roles in the petrologic history of these meteorites. It is therefore possible that these processes have obscured the petrogenetic linkages between the enriched olivine-phyric shergottites and the pyroxene-plagioclase shergottites. As a first order step in attempting to unravel these petrologic complexities, this study focuses upon exploring the effect of fO2 on the crystallization history for an analog primitive shergottite liquid composition (Y98). Results from this work will provide a basis for reconstructing the record of fO2 in shergottites, its effect on both mineral chemistries and valence state partitioning, and a means for examining the role of crystallization on the petrologic linkages between olivine-phyric and pyroxene-plagioclase shergottites. A companion abstract [4] explores the behavior of V over this range of fO2.

  18. Valence State Partitioning of Cr and V Between Pyroxene - Melt: Estimates of Oxygen Fugacity for Martian Basalt QUE 94201

    NASA Technical Reports Server (NTRS)

    Karner, J. M.; Papike, J. J.; Shearer, C. K.; McKay, G.; Le, L.; Burger, P.

    2007-01-01

    Several studies, using different oxybarometers, have suggested that the variation of fO2 in martian basalts spans about 3 log units from approx. IW-1 to IW+2. The relatively oxidized basalts (e.g., pyroxene-phyric Shergotty) are enriched in incompatible elements, while the relatively reduced basalts (e.g., olivine-phyric Y980459) are depleted in incompatible elements. A popular interpretation of the above observations is that the martian mantle contains two reservoirs; 1) oxidized and enriched, and 2) reduced and depleted. The basalts are thus thought to represent mixing between these two reservoirs. Recently, Shearer et al. determined the fO2 of primitive olivine-phyric basalt Y980459 to be IW+0.9 using the partitioning of V between olivine and melt. In applying this technique to other basalts, Shearer et al. concluded that the martian mantle shergottite source was depleted and varied only slightly in fO2 (IW to IW+1). Thus the more oxidized, enriched basalts had assimilated a crustal component on their path to the martian surface. In this study we attempt to address the above debate on martian mantle fO2 using the partitioning of Cr and V into pyroxene in pyroxene-phyric basalt QUE 94201.

  19. Siderophile Trace Elements in ALH 84001 and Other Achondrites: A Temporal Increase of Oxygen Fugacity in the Martian Mantle?

    NASA Astrophysics Data System (ADS)

    Warren, P. H.; Kallemeyn, G. W.

    1995-09-01

    We have employed neutron activation, including radiochemical NAA, to investigate SNC/martian meteorites ALH 77005, ALH 84001 and LEW 88516, along with 15 eucrites. Our data for 10 manifestly monomict eucrites confirm previous indications [e.g., 1] that compositionally pristine eucrites are generally extremely siderophile-poor, although for several of the most extremely siderophile-depleted eucrites we find slight enhancements in Re/Os (Figure). Our RNAA data are the first for highly siderophile elements in polymict eucrites, and show a broad similarity with lunar polymict breccias. In general, our data (e.g., Ga/Al = 4.3x10^-4) confirm SNC affinity [2] for ALH84001. However, siderophile concentrations are, by SNC standards, extraordinarily low: Ni = 5.8 micrograms/g and (in pg/g) Au = 9.4, Ir = 80, Os = 10.2, and Re = 1.66+/-0.25(1-s); Ge (1080 ng/g) is typical for SNCs. Like terrestrial basalts [1], other SNCs have relatively constant Re, ranging from 28 (Lafayette [3]) to 102 pg/g (ALH 77005) among seven analyzed meteorites of various types, in which Os ranges from <2.3 to 4400 pg/g. A plot of Os vs. Re/Os (Figure) shows that ALH 84001 has 23x lower Re than expected for a young SNC of similar Os content. On Earth, Re generally behaves as a mildly incompatible element, whereas Os behaves as a strongly compatible element. A plausible explanation for this divergence [1] is that Re is more prone to enter higher oxidation states, such as Re^4+, which would tend to behave like W^4+. This model is consistent with the Os-like behavior of Re in the highly reduced lunar and eucritic environments, and Birck and Allegre [1] interpret the typically intermediate Re contents of SNCs as suggestive of origin from a mantle source region at intermediate fO(sub)2 (they also considered, but rejected, an implausible "contamination" model). Extended to ALH 84001, this model implies that the mantle source was at a substantially (roughly 1.7 log(sub)10 units) lower fO2 than the analogous sources of the younger SNCs. Conceivably ALH84001 siderophiles were altered by metasomatic processes [cf. 2]. However, near-surface processing on a heavily cratered body would generally tend to add siderophile material, rather than remove it. Also, Treiman [4] argues that alteration took place strictly at low temperatures. Another possible objection is that unlike eucrites and lunar basalts, ALH84001 is rich in Fe^3+ [2]. However, if the parent magma encountered even a small proportion of water in the upper crust of Mars, the final fO(sub)2 would be substantially raised. Many authors have proposed that the terrestrial planets in general, and Mars in particular, were originally very dry, implying low fO(sub)2, and that only late in accretion history did substantial proportions of oxidizing volatiles accrete as a "veneer". Possibly when ALH84001 formed, 4.50+/-0.13 Ga [5], oxidation had not yet altered the primordial, low fO(sub)2 nature of its mantle source region. It is also conceivable that large portions of the martian mantle never reached fO(sub)2 as high as inferred for the younger SNCs (possibly derived from a single crater). In any case, the siderophile-depletion pattern of ALH 84001 is unique among SNCs. References: [1] Birck J. L. and All gre C. J. (1994) EPSL, 124, 139-148. [2] Mittlefehldt D. W. (1994) Meteoritics, 29, 214-221. [3] Treiman A. H. et al. (1986) GCA, 50, 1071-1091. [4] Treiman A. H. (1995) Meteoritics, 30, 294-302. [5] Nyquist L. E. et al. (1995) LPS, XXVI, 1065-1066.

  20. A general model to calculate the spin-lattice (T1) relaxation time of blood, accounting for haematocrit, oxygen saturation and magnetic field strength.

    PubMed

    Hales, Patrick W; Kirkham, Fenella J; Clark, Christopher A

    2016-02-01

    Many MRI techniques require prior knowledge of the T1-relaxation time of blood (T1bl). An assumed/fixed value is often used; however, T1bl is sensitive to magnetic field (B0), haematocrit (Hct), and oxygen saturation (Y). We aimed to combine data from previous in vitro measurements into a mathematical model, to estimate T1bl as a function of B0, Hct, and Y. The model was shown to predict T1bl from in vivo studies with a good accuracy (± 87 ms). This model allows for improved estimation of T1bl between 1.5-7.0 T while accounting for variations in Hct and Y, leading to improved accuracy of MRI-derived perfusion measurements.

  1. Large-scale QM/MM calculations of the CaMn4O5 cluster in the oxygen-evolving complex of photosystem II: Comparisons with EXAFS structures

    NASA Astrophysics Data System (ADS)

    Shoji, Mitsuo; Isobe, Hiroshi; Nakajima, Takahito; Yamaguchi, Kizashi

    2016-08-01

    Large-scale QM/MM calculations including hydrogen-bonding networks in the oxygen evolving complex (OEC) of photosystem II (PSII) were performed to elucidate the geometric structures of the CaMn4O5 cluster in the key catalytic states (Si (i = 0-3)). The optimized Mn-Mn, Ca-Mn and Mn-O distances by the large-scale QM/MM starting from the high-resolution XRD structure were consistent with those of the EXAFS experiments in the dark stable S1 state by the Berkeley and Berlin groups. The optimized geometrical parameters for other Si (i = 0, 2, 3) states were also consistent with those of EXAFS, indicating the importance of the large-scale QM/MM calculations for the PSII-OEC.

  2. Risk assessment of butyltins based on a fugacity-based food web bioaccumulation model in the Jincheng Bay mariculture area: I. Model development.

    PubMed

    Hu, Yanbing; Gong, Xianghong; Xu, Yingjiang; Song, Xiukai; Liu, Huihui; Deng, Xuxiu; Ru, Shaoguo

    2014-08-01

    A fugacity-based model was developed to simulate the bioaccumulation of butyltins in the food web of the Jincheng Bay mariculture area. The predicted biological tissue residues of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) were 0.04-17.09, 0.14-53.54, and 0.27-108.77 ng-Sn g(-1), respectively, and the predicted values in six mollusca agreed well with the measured ones. The lipid-normalized concentrations did not significantly increase across trophic levels, indicating no biomagnification across aquatic food webs. These results were highly consistent with those observed both in the laboratory and field, which had been reported in numerous references. The explanation, from calculating their flux equilibrium in the food web, was that butyltins were primarily taken in via respiration from the water column by marine organisms. The sensitivities of the model parameters were analyzed, revealing that the hydrophobicity of butyltins played the dominant role in their bioaccumulation phenomena. The verified model predictions of the biotic tissue concentrations of the butyltins could be readily applied to perform internal ecological risk and human health risk assessments in this area.

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  4. The calculated solubility of platinum and gold in oxygen-saturated fluids and the genesis of platinum-palladium and gold mineralization in the unconformity-related uranium deposits

    NASA Astrophysics Data System (ADS)

    Jaireth, S.

    1992-01-01

    Thermodynamic calculations on the solubility of platinum and gold indicate that saline (1 m NaCl), fluids saturated with atmospheric oxygen can transport geologically realistic concentrations of platinum-group-elements (PGE), gold, and uranium as chloro-complexes. A number of calculations involving fluid-rock interaction suggest that the oxygen-saturated fluids flowing through rocks containing quartz, muscovite, kaolinite, magnetite and hematite, initially oxidize any magnetite to hematite, allowing subsequent batches of ore fluids to retain their high oxidation state. During their migration through the aquifer, the oxidizing fluids would move the oxidation-reduction interface deeper into the aquifer, leaching and redepositing platinum and gold. The redissolution of earlier precipitated platinum and gold depends on the fluid/ rock ratio and the associated increase in the oxidation state. Therefore, lowering of fluid/rock ratios and/or mixing of the oxidized fluids with a large amount of reduced fluid will precipitate uranium, PGE, and gold. It is suggested that this model can explain the genesis of gold and PGE mineralization in the unconformity-related uranium deposits of the Alligator Rivers Uranium Field in the Northern Territory, Australia.

  5. EQ3NR, a computer program for geochemical aqueous speciation-solubility calculations: Theoretical manual, user`s guide, and related documentation (Version 7.0); Part 3

    SciTech Connect

    Wolery, T.J.

    1992-09-14

    EQ3NR is an aqueous solution speciation-solubility modeling code. It is part of the EQ3/6 software package for geochemical modeling. It computes the thermodynamic state of an aqueous solution by determining the distribution of chemical species, including simple ions, ion pairs, and complexes, using standard state thermodynamic data and various equations which describe the thermodynamic activity coefficients of these species. The input to the code describes the aqueous solution in terms of analytical data, including total (analytical) concentrations of dissolved components and such other parameters as the pH, pHCl, Eh, pe, and oxygen fugacity. The input may also include a desired electrical balancing adjustment and various constraints which impose equilibrium with special pure minerals, solid solution end-member components (of specified mole fractions), and gases (of specified fugacities). The code evaluates the degree of disequilibrium in terms of the saturation index (SI = 1og Q/K) and the thermodynamic affinity (A = {minus}2.303 RT log Q/K) for various reactions, such as mineral dissolution or oxidation-reduction in the aqueous solution itself. Individual values of Eh, pe, oxygen fugacity, and Ah (redox affinity) are computed for aqueous redox couples. Equilibrium fugacities are computed for gas species. The code is highly flexible in dealing with various parameters as either model inputs or outputs. The user can specify modification or substitution of equilibrium constants at run time by using options on the input file.

  6. A fugacity approach for assessing the bioaccumulation of hydrophobic organic compounds from estuarine sediment.

    PubMed

    Golding, Christopher J; Gobas, Frank A P C; Birch, Gavin F

    2008-05-01

    The bioavailability of four sediment-spiked hydrophobic organic contaminants (HOCs; chrysene, benzo[a]pyrene, chlordane, and Aroclor 1254) was investigated by comparing bioaccumulation by the amphipod Corophium colo with uptake into a thin film of ethylene/vinyl acetate (EVA) copolymer. The EVA thin film is a solid-phase extraction medium previously identified as effective at measuring the bioavailable contaminant fraction in sediment. The present study presents the results of 11 separate treatments in which chemical uptake into EVA closely matched uptake into lipid over 10 d. For all compounds, the concentration in EVA was a good approximation for the concentration in lipid, suggesting that this medium would be an appropriate biomimetic medium for assessing the bioaccumulation of HOCs during risk assessment of contaminated sediment. For chrysene and benzo[a]pyrene, limitations on bioaccumulation and toxicity because of low aqueous solubility were observed. The fugacity of the compounds in lipid (flip) and in the EVA thin film (fEVA) also was determined. The ratio of flip to fEVA was greater than one for all chemicals, indicating that all chemicals biomagnified over the duration of the exposure and demonstrating the potential for EVA thin-film extraction to assess trophic transfer of HOCs.

  7. An empirical model for the calculation of spinel-melt equilibria in mafic igneous systems at atmospheric pressure: 1. Chromian spinels

    NASA Astrophysics Data System (ADS)

    Ariskin, A. A.; Nikolaev, Georgy S.

    1996-04-01

    In order to develop a model for simulating naturally occurring chromian spinel compositions, we have processed published experimental data on chromian spinel-melt equilibrium. Out of 259 co-existing spinel-melt experiments reported in the literature, we have selected 118 compositions on the basis of run time, melt composition and experimental technique. These data cover a range of temperatures 1150 1500° C, oxygen fugacities of -13oxygen fugacity at 1 atmosphere pressure (0.101 MPa). The empirically calibrated mineral-melt expression based on multiple linear regressions is: K Sp i =A/T(K)+B log f O2+C ln (Fe3+/Fe2+)L+D ln R L +E, where K Sp i is an equilibrium constant and R L is a melt structure-chemical parameter ( MSCP). Twenty-eight forms of equilibrium constants were considered, including single distribution coefficients, exchange equilibrium constants, formation constants for AB2O4 components, as well as simple “spinel cation ratios”. For each form of the equilibrium constants, a set of 16 combinations of the MSCPs have been investigated. The MSCP is present in the form of composite ratios [e.g., Si/O, NBO/T,(Al+Si)/Si, or (Na+K)/Al] or as simple cation ratios (e.g., Mg/Fe2+). For the calculation of Fe3+ and Fe2+ species in silicate melts, we used existing equations, whereas the Fe3+/Fe2+ ratio of spinels was calculated from the spinel stoichiometry. The regression parameters that best repoduce the experimental data were for the following constants: (Fe3+/Fe2+) Sp , (Mg/Fe2+) Sp /(Mg/Fe2+) L , (Cr/Al) Sp / (Cr/Al) L , K FeCr2O4, and Ti Sp /Ti L . These expressions have been combined into a single program called SPINMELT, which calculates chromite crystallization

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

    NASA Technical Reports Server (NTRS)

    Molnar, Melissa; Marek, C. John

    2005-01-01

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

  9. Theoretical investigations of the γ- gauche effect on the 13C chemical shifts produced by oxygen atoms at the γ position by quantum chemistry calculations

    NASA Astrophysics Data System (ADS)

    Suzuki, Shinji; Horii, Fumitaka; Kurosu, Hiromichi

    2009-02-01

    The γ- gauche effect on 13C chemical shifts that is produced by the O atoms located at the γ positions has been evaluated by quantum chemistry calculations based on the GAIO-CHF procedure. The γ- gauche effects produced by the O and Cl atoms in n-propanol and n-propyl chloride are found to be, respectively, +1.4 and -0.7 ppm, whereas that due to the C atom in n-butane is -3.0 ppm in good agreement of the values previously calculated. The apparent cause of such a difference in the γ- gauche effect is mainly relatively higher shielding of the CH 3 carbon in the trans conformation for the n-propanol and n-propyl chloride. Extending the n-propanol chain at both ends causes no significant change in the γ- gauche effect produced by the O atom. In 2-butanol and 2-methyl-2-butanol as examples of secondarily and tertiarily substituted compounds, the γ- gauche effects produced by the γ-OH groups are estimated to be -7 to -9 ppm. In addition, the γ- gauche effect due to the C atom is found to increase in n-butane, secondary, and tertiary butanols in this order. The γ- gauche effect produced by the O atom in hydroxyethylcyclohexane is as negligibly small as -0.7 ppm, whereas that produced by the C atom in ethylcyclohexane is about -5 ppm. These results suggest that the γ- gauche effect, including downfield shift, produced by the O atom in a compound greatly depends on its chemical structure, whereas upfield shifts of -3 to -7 ppm are induced in all examined compounds as the γ- gauche effect due to the C atom.

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

    NASA Technical Reports Server (NTRS)

    Marek, C. John; Molnar, Melissa

    2005-01-01

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

  11. 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.

  12. The Abandoned E-Waste Recycling Site Continued to Act As a Significant Source of Polychlorinated Biphenyls: An in Situ Assessment Using Fugacity Samplers.

    PubMed

    Wang, Yan; Luo, Chunling; Wang, Shaorui; Cheng, Zhineng; Li, Jun; Zhang, Gan

    2016-08-16

    The recycling of e-waste has attracted significant attention due to emissions of polychlorinated biphenyls (PCBs) and other contaminants into the environment. We measured PCB concentrations in surface soils, air equilibrated with the soil, and air at 1.5-m height using a fugacity sampler in an abandoned electronic waste (e-waste) recycling site in South China. The total concentrations of PCBs in the soils were 39.8-940 ng/g, whereas the concentrations in air equilibrated with the soil and air at 1.5 m height were 487-8280 pg/m(3) and 287-7380 pg/m(3), respectively. The PCB concentrations displayed seasonal variation; they were higher in winter in the soils and higher in summer in the air, indicating that the emission of PCBs from the soil was enhanced during hot seasons for the relatively high temperature or additional sources, especially for low-chlorinated PCBs. We compared two methods (traditional fugacity model and fugacity sampler) for assessing the soil-air partition coefficients (Ksa) and the fugacity fractions of PCBs. The results suggested that the fugacity sampler provided more instructive and practical estimation on Ksa values and trends in air-soil exchange, especially for low-chlorinated PCBs. The abandoned e-waste burning site still acted as a significant source of PCBs many years after the prohibition on open burning.

  13. Large-scale QM/MM calculations of the CaMn4O5 cluster in the S3 state of the oxygen evolving complex of photosystem II. Comparison between water-inserted and no water-inserted structures.

    PubMed

    Shoji, Mitsuo; Isobe, Hiroshi; Nakajima, Takahito; Shigeta, Yasuteru; Suga, Michihiro; Akita, Fusamichi; Shen, Jian-Ren; Yamaguchi, Kizashi

    2017-03-09

    Large-scale QM/MM calculations were performed to elucidate an optimized geometrical structure of a CaMn4O5 cluster with and without water insertion in the S3 state of the oxygen evolving complex (OEC) of photosystem II (PSII). The left (L)-opened structure was found to be stable under the assumption of no hydroxide anion insertion in the S3 state, whereas the right (R)-opened structure became more stable if one water molecule is inserted to the Mn4Ca cluster. The optimized Mna(4)-Mnd(1) distance determined by QM/MM was about 5.0 Å for the S3 structure without an inserted hydroxide anion, but this is elongated by 0.2-0.3 Å after insertion. These computational results are discussed in relation to the possible mechanisms of O-O bond formation in water oxidation by the OEC of PSII.

  14. Fugacity modelling to predict the distribution of organic contaminants in the soil:oil matrix of constructed biopiles.

    PubMed

    Pollard, Simon J T; Hough, Rupert L; Kim, Kye-Hoon; Bellarby, Jessica; Paton, Graeme; Semple, Kirk T; Coulon, Frédéric

    2008-04-01

    Level I and II fugacity approaches were used to model the environmental distribution of benzene, anthracene, phenanthrene, 1-methylphenanthrene and benzo[a]pyrene in a four phase biopile system, accounting for air, water, mineral soil and non-aqueous phase liquid (oil) phase. The non-aqueous phase liquid (NAPL) and soil phases were the dominant partition media for the contaminants in each biopile and the contaminants differed markedly in their individual fugacities. Comparison of three soils with different percentage of organic carbon (% org C) showed that the % org C influenced contaminant partitioning behaviour. While benzene showed an aqueous concentration worthy of note for leachate control during biopiling, other organic chemicals showed that insignificant amount of chemicals leached into the water, greatly reducing the potential extent of groundwater contamination. Level II fugacity model showed that degradation was the dominant removal process except for benzene. In all three biopile systems, the rate of degradation of benzo(a)pyrene was low, requiring more than 12 years for soil concentrations from a spill of about 25 kg (100 mol) to be reduced to a concentration of 0.001 microgg(-1). The removal time of 1-methylphenanthrene and either anthracene or phenanthrene was about 1 and 3 years, respectively. In contrast, benzene showed the highest degradation rate and was removed after 136 days in all biopile systems. Overall, this study confirms the association of risk critical contaminants with the residual saturation in treated soils and reinforces the importance of accounting for the partitioning behaviour of both NAPL and soil phases during the risk assessment of oil-contaminated sites.

  15. O2 and H2O2 transformation steps for the oxygen reduction reaction catalyzed by graphitic nitrogen-doped carbon nanotubes in acidic electrolyte from first principles calculations.

    PubMed

    Li, Yuhang; Zhong, Guoyu; Yu, Hao; Wang, Hongjuan; Peng, Feng

    2015-09-14

    It is highly challenging but extremely desirable to develop carbon catalysts with high oxygen reduction reaction (ORR) activity and stability in acidic medium for commercial application. In this paper, based on density functional theory (DFT) calculations with long range interaction correction and solvation effects, the elementary transformations of all the probable intermediates in the ORR and the hydrogen peroxide reduction reaction (HPRR) over graphitic nitrogen-doped carbon nanotubes (NCNTs) in acidic medium were evaluated, and it was found that all the rate determining steps are related to the bonding hydroxyl group because of the strong interaction between the hydroxyl group and carbon. Thus, it is hard for the direct four-electron ORR and the two-electron HPRR to proceed. Together with hydrogen peroxide disproportionation (HPD), a mixed mechanism for the ORR in acidic electrolyte was proposed, where the two-electron and three-electron ORRs and HPD dominate the electrode reaction. The experimental result for the ORR catalyzed by NCNTs in acidic electrolyte also well illustrated the rationality of the theoretical calculations. This study not only gives new insights into the effect of graphitic nitrogen doping on the ORR catalyzed by carbon, but also provides a guide to design carbon catalysts with high ORR activity in acidic electrolyte.

  16. Using oxygen at home

    MedlinePlus

    Oxygen - home use; COPD - home oxygen; Chronic obstructive airways disease - home oxygen; Chronic obstructive lung disease - home oxygen; Chronic bronchitis - home oxygen; Emphysema - home oxygen; Chronic respiratory ...

  17. The electrum-tarnish method for the determination of the fugacity of sulfur in laboratory sulfide systems

    USGS Publications Warehouse

    Barton, P.B.; Toulmin, P.

    1964-01-01

    A new method for the determination of the fugacity of sulfur in laboratory systems consists of visual observation of the development and decomposition of a sulfide tarnish phase on silver-gold alloy (electrum) of precisely known composition. The alloy system is calibrated against pure sulfur. The method has the following advantages: simple apparatus; ability to cover a large range of fugacity of S2; ability to cover a large temperature range by permitting runs of long duration; ability to tolerate other components in the gas phase; and ease of recovery of the quenched charges for determinations of phases and compositions. Results obtained by the electrum-tarnish method are in satisfactory agreement with those obtained by other workers for the fs2 vs. T curves for the assemblage Ni(1-x)S + NiS2. The electrum-tarnish method shows promise for investigating many other reactions. Univariant reactions studied by this method can be represented as lines forming a genetic grid in terms of the environmental parameters fs2 and T, The slopes of such lines can yield valuable thermodynamic data for the phases involved, but activity coefficients must be known for phases of variable composition. ?? 1964.

  18. 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.

  19. 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.

  20. 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 ...

  1. [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.

  2. 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.

  3. Evaluating potential non-point source loading of PAHs from contaminated soils: a fugacity-based modeling approach.

    PubMed

    Luo, Xiaolin; Zheng, Yi; Lin, Zhongrong; Wu, Bin; Han, Feng; Tian, Yong; Zhang, Wei; Wang, Xuejun

    2015-01-01

    Soils contaminated by Polycyclic Aromatic Hydrocarbons (PAHs) are subject to significant non-point source (NPS) pollution during rainfall events. Recent studies revealed that the classic enrichment ratio (ER) approach may not be applicable to PAHs. This study developed a model to estimate the ER of PAHs which innovatively applies the fugacity concept. The ER model has been validated with experimental data, which suggested that the transport of PAHs not only depends on their physicochemical properties, but on the sediment composition and how the composition evolves during the event. The modeling uncertainty was systematically examined, and found to be highly compound-dependent. Based on the ER model, a strategy was proposed to practically evaluate the potential NPS loading of PAHs in watersheds with heterogeneous soils. The study results have important implications to modeling and managing the NPS pollution of PAHs (or other chemicals alike) at a watershed scale.

  4. Mantle Water Fugacity is the Dominant Factor in Total Strength and Stability/Mobility of Continental Lithosphere

    NASA Astrophysics Data System (ADS)

    Lowry, A. R.; Schutt, D.; Perez-Gussinye, M.; Ma, X.; Berry, M. A.; Ravat, D.

    2014-12-01

    More than half a century after the plate tectonic revolution, the physical mechanism that distinguishes tectonically active plate boundaries from stable continental interiors remains nebulous. Rock flow strength and mass density variations both contribute to stress, so both are certain to be important, but these depend ambiguously on rock lithology, temperature, and concentrations of water. High seismic velocities observed to great depths often are interpreted as evidence that geothermal variations dominate patterns of lithospheric strength. However, mantle seismic velocities are sensitive to flow-induced anelastic attenuation as well as to temperature. A more ductile mantle will propagate waves more slowly regardless of whether low viscosity is a consequence of high temperature or of high water fugacity, complicating interpretations of seismic velocity in the absence of other constraints. Here we use EarthScope's USArray seismic data to independently constrain crustal thickness, bulk crustal lithology and Moho temperature of the lithosphere, and magnetic bottom measurements to refine the crustal geotherm. Strength models based on these quantities are then compared to integral measurements of western U.S. isostatic strength expressed as effective elastic thickness, Te. We show that mantle water is the primary factor that distinguishes stable lithosphere of North America's cratonic interior from actively deforming zones in the western U.S. Cordillera. Seismic and magnetic constraints on temperature and lithology variations can be reconciled with integral strength measurements only if water fugacity within the lithospheric column is permitted to vary from near-saturation in deforming, mobile lithosphere to nearly completely dry in the stable cratonic interior.

  5. Transport properties of oxygen

    NASA Technical Reports Server (NTRS)

    Roder, H. M.

    1983-01-01

    Tables of viscosity, thermal conductivity, and thermal diffusivity of oxygen as a function of temperature and pressure from the triple point to 320 K and at pressures to 100 MPa are presented. Auxiliary tables in engineering units are also given. Viscosity and thermal conductivity are calculated from published correlations. Density and specific heat at constant pressure, required to calculate thermal diffusivity, are obtained from an equation of state. The Prandtl number can be obtained quite easily from the values tabulated.

  6. A New Oxygen Barometer for Solar System Basaltic Glasses Based on Vanadium Valence

    NASA Technical Reports Server (NTRS)

    Karner, J. M.; Sutton, S. R.; Papike, S. R.; Delaney, J. S.; Shearer, C. K.; Newville, M.; Eng, P.; Rivers, M.; Dyar, M. D.

    2004-01-01

    The determination of oxidation conditions for basaltic magmas derived by the melting of planetary mantles is critical to our understanding of the nature and evolution of planetary interiors. Yet, these determinations are compromised in terrestrial and especially extraterrestrial basalts by our analytical and computational methods for estimating oxygen fugacity (fO2). For example, mineralogical barometers (1, 2) can be reduced in effectiveness by subsolidus re-equilibration of mineral assemblages, inversion of mineralogical data to melt characteristics, and deviations of the natural mineral compositions from ideal thermodynamic parameters.

  7. Generalized approximate spin projection calculations of effective exchange integrals of the CaMn4O5 cluster in the S1 and S3 states of the oxygen evolving complex of photosystem II.

    PubMed

    Isobe, H; Shoji, M; Yamanaka, S; Mino, H; Umena, Y; Kawakami, K; Kamiya, N; Shen, J-R; Yamaguchi, K

    2014-06-28

    Full geometry optimizations followed by the vibrational analysis were performed for eight spin configurations of the CaMn4O4X(H2O)3Y (X = O, OH; Y = H2O, OH) cluster in the S1 and S3 states of the oxygen evolution complex (OEC) of photosystem II (PSII). The energy gaps among these configurations obtained by vertical, adiabatic and adiabatic plus zero-point-energy (ZPE) correction procedures have been used for computation of the effective exchange integrals (J) in the spin Hamiltonian model. The J values are calculated by the (1) analytical method and the (2) generalized approximate spin projection (AP) method that eliminates the spin contamination errors of UB3LYP solutions. Using J values derived from these methods, exact diagonalization of the spin Hamiltonian matrix was carried out, yielding excitation energies and spin densities of the ground and lower-excited states of the cluster. The obtained results for the right (R)- and left (L)-opened structures in the S1 and S3 states are found to be consistent with available optical and magnetic experimental results. Implications of the computational results are discussed in relation to (a) the necessity of the exact diagonalization for computations of reliable energy levels, (b) magneto-structural correlations in the CaMn4O5 cluster of the OEC of PSII, (c) structural symmetry breaking in the S1 and S3 states, and (d) the right- and left-handed scenarios for the O-O bond formation for water oxidation.

  8. 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…

  9. Risk assessment of butyltins based on a fugacity-based food web bioaccumulation model in the Jincheng Bay mariculture area: II. Risk assessment.

    PubMed

    Hu, Yanbing; Song, Xiukai; Gong, Xianghong; Xu, Yingjiang; Liu, Huihui; Deng, Xuxiu; Ru, Shaoguo

    2014-08-01

    A fugacity-based food web bioaccumulation model was constructed, and the biotic concentrations of butyltins in the food web of the Jincheng Bay mariculture area were estimated accordingly, using the water and sediment concentrations described in the accompanying paper (Part I). This paper presents an ecological risk assessment (ERA) and a human health risk assessment (HHRA) of the butyltins, based on the estimated tissue residues in the marine life in this area. The results showed that the ecological risk probability was greater than 0.05. At this level, management control is critical since sensitive marine species would be profoundly endangered by butyltin contamination. Few if any detrimental effects, however, would be generated for humans from exposure to butyltins through seafood consumption. The fugacity-based model can refine the ERA and HHRA of pollutants in marine areas, provide a basis for protecting marine ecology and the security of fishery products, and thus help determine the feasibility of a proposed aquaculture project.

  10. Oxygen safety

    MedlinePlus

    ... with electric motors Electric baseboard or space heaters Wood stoves, fireplaces, candles Electric blankets Hairdryers, electric razors, ... Therapy.aspx . Accessed February 9, 2016. National Fire Protection Association. Medical oxygen. Updated July 2013. www.nfpa. ...

  11. Bolus calculators.

    PubMed

    Schmidt, Signe; Nørgaard, Kirsten

    2014-09-01

    Matching meal insulin to carbohydrate intake, blood glucose, and activity level is recommended in type 1 diabetes management. Calculating an appropriate insulin bolus size several times per day is, however, challenging and resource demanding. Accordingly, there is a need for bolus calculators to support patients in insulin treatment decisions. Currently, bolus calculators are available integrated in insulin pumps, as stand-alone devices and in the form of software applications that can be downloaded to, for example, smartphones. Functionality and complexity of bolus calculators vary greatly, and the few handfuls of published bolus calculator studies are heterogeneous with regard to study design, intervention, duration, and outcome measures. Furthermore, many factors unrelated to the specific device affect outcomes from bolus calculator use and therefore bolus calculator study comparisons should be conducted cautiously. Despite these reservations, there seems to be increasing evidence that bolus calculators may improve glycemic control and treatment satisfaction in patients who use the devices actively and as intended.

  12. Response of sea surface fugacity of CO2 to the SAM shift south of Tasmania: Regional differences

    NASA Astrophysics Data System (ADS)

    Xue, Liang; Gao, Libao; Cai, Wei-Jun; Yu, Weidong; Wei, Meng

    2015-05-01

    Using observational data collected south of Tasmania during 14 austral summer cruises during 1993-2011, we examined the response of sea surface fugacity of carbon dioxide (fCO2) to the Southern Annular Mode (SAM) shift, which occurred around 2000. In the southern part of the Southern Ocean (SO) or the Polar Zone (PZ) and the Polar Frontal Zone (PFZ), fCO2 increased faster at the sea surface than in the atmosphere before the SAM shift, but not after the shift. In the northern part of the SO or the Subantarctic Zone (SAZ), however, surface fCO2 increased faster than atmospheric fCO2 both before and after the shift. The SAM shift had an important influence on the surface fCO2 trend in the PZ and PFZ but not in the SAZ, which we attribute to differences in regional oceanographic processes (upwelling versus nonupwelling). The SAM shift may have reversed the negative trend of SO CO2 uptake.

  13. Spatial Distribution, Air-Water Fugacity Ratios and Source Apportionment of Polychlorinated Biphenyls in the Lower Great Lakes Basin.

    PubMed

    Khairy, Mohammed; Muir, Derek; Teixeira, Camilla; Lohmann, Rainer

    2015-12-01

    Polychlorinated biphenyls (PCBs) continue to be contaminants of concern across the Great Lakes. It is unclear whether current concentrations are driven by ongoing primary emissions from their original uses, or whether ambient PCBs are dominated by their environmental cycling. Freely dissolved PCBs in air and water were measured using polyethylene passive samplers across Lakes Erie and Ontario during summer and fall, 2011, to investigate their spatial distribution, determine and apportion their sources and to asses their air-water exchange gradients. Average gaseous and freely dissolved ∑29 PCB concentrations ranged from 5.0 to 160 pg/m(3) and 2.0 to 55 pg/L respectively. Gaseous concentrations were significantly correlated (R(2) = 0.80) with the urban area within a 3-20 km radius. Fugacity ratios indicated that the majority of PCBs are volatilizing from the water thus acting as a secondary source for the atmosphere. Dissolved PCBs were probably linked to PCB emissions from contaminated sites and areas of concern. Positive matrix factorization indicated that although volatilized Aroclors (gaseous PCBs) and unaltered Aroclors (dissolved PCBs) dominate in some samples, ongoing non-Aroclor sources such as paints/pigments (PCB 11) and coal/wood combustion showed significant contributions across the lower Great Lakes. Accordingly, control strategies should give further attention to PCBs emitted from current use sources.

  14. In vivo measurement, in vitro estimation and fugacity prediction of PAH bioavailability in post-remediated creosote-contaminated soil.

    PubMed

    Juhasz, Albert L; Weber, John; Stevenson, Gavin; Slee, Daniel; Gancarz, Dorota; Rofe, Allan; Smith, Euan

    2014-03-01

    In this study, PAH bioavailability was assessed in creosote-contaminated soil following bioremediation in order to determine potential human health exposure to residual PAHs from incidental soil ingestion. Following 1,000 days of enhanced natural attenuation (ENA), a residual PAH concentration of 871 ± 8 mg kg(-1) (∑16 USEPA priority PAHs in the <250 μm soil particle size fraction) was present in the soil. However, when bioavailability was assessed to elucidate potential human exposure using an in vivo mouse model, the upper-bound estimates of PAH absolute bioavailability were in excess of 65% irrespective of the molecular weight of the PAH. These results indicate that a significant proportion of the residual PAH fraction following ENA may be available for absorption following soil ingestion. In contrast, when PAH bioavailability was estimated/predicted using an in vitro surrogate assay (FOREhST assay) and fugacity modelling, PAH bioavailability was up to 2000 times lower compared to measured in vivo values depending on the methodology used.

  15. 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.

  16. 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

  17. Timescales of Oxygenation Following the Evolution of Oxygenic Photosynthesis.

    PubMed

    Ward, Lewis M; Kirschvink, Joseph L; Fischer, Woodward W

    2016-03-01

    Among the most important bioenergetic innovations in the history of life was the invention of oxygenic photosynthesis-autotrophic growth by splitting water with sunlight-by Cyanobacteria. It is widely accepted that the invention of oxygenic photosynthesis ultimately resulted in the rise of oxygen by ca. 2.35 Gya, but it is debated whether this occurred more or less immediately as a proximal result of the evolution of oxygenic Cyanobacteria or whether they originated several hundred million to more than one billion years earlier in Earth history. The latter hypothesis involves a prolonged period during which oxygen production rates were insufficient to oxidize the atmosphere, potentially due to redox buffering by reduced species such as higher concentrations of ferrous iron in seawater. To examine the characteristic timescales for environmental oxygenation following the evolution of oxygenic photosynthesis, we applied a simple mathematical approach that captures many of the salient features of the major biogeochemical fluxes and reservoirs present in Archean and early Paleoproterozoic surface environments. Calculations illustrate that oxygenation would have overwhelmed redox buffers within ~100 kyr following the emergence of oxygenic photosynthesis, a geologically short amount of time unless rates of primary production were far lower than commonly expected. Fundamentally, this result arises because of the multiscale nature of the carbon and oxygen cycles: rates of gross primary production are orders of magnitude too fast for oxygen to be masked by Earth's geological buffers, and can only be effectively matched by respiration at non-negligible O2 concentrations. These results suggest that oxygenic photosynthesis arose shortly before the rise of oxygen, not hundreds of millions of years before it.

  18. Timescales of Oxygenation Following the Evolution of Oxygenic Photosynthesis

    NASA Astrophysics Data System (ADS)

    Ward, Lewis M.; Kirschvink, Joseph L.; Fischer, Woodward W.

    2016-03-01

    Among the most important bioenergetic innovations in the history of life was the invention of oxygenic photosynthesis—autotrophic growth by splitting water with sunlight—by Cyanobacteria. It is widely accepted that the invention of oxygenic photosynthesis ultimately resulted in the rise of oxygen by ca. 2.35 Gya, but it is debated whether this occurred more or less immediately as a proximal result of the evolution of oxygenic Cyanobacteria or whether they originated several hundred million to more than one billion years earlier in Earth history. The latter hypothesis involves a prolonged period during which oxygen production rates were insufficient to oxidize the atmosphere, potentially due to redox buffering by reduced species such as higher concentrations of ferrous iron in seawater. To examine the characteristic timescales for environmental oxygenation following the evolution of oxygenic photosynthesis, we applied a simple mathematical approach that captures many of the salient features of the major biogeochemical fluxes and reservoirs present in Archean and early Paleoproterozoic surface environments. Calculations illustrate that oxygenation would have overwhelmed redox buffers within ~100 kyr following the emergence of oxygenic photosynthesis, a geologically short amount of time unless rates of primary production were far lower than commonly expected. Fundamentally, this result arises because of the multiscale nature of the carbon and oxygen cycles: rates of gross primary production are orders of magnitude too fast for oxygen to be masked by Earth's geological buffers, and can only be effectively matched by respiration at non-negligible O2 concentrations. These results suggest that oxygenic photosynthesis arose shortly before the rise of oxygen, not hundreds of millions of years before it.

  19. Retinal oxygen extraction in humans

    NASA Astrophysics Data System (ADS)

    Werkmeister, René M.; Schmidl, Doreen; Aschinger, Gerold; Doblhoff-Dier, Veronika; Palkovits, Stefan; Wirth, Magdalena; Garhöfer, Gerhard; Linsenmeier, Robert A.; Leitgeb, Rainer A.; Schmetterer, Leopold

    2015-10-01

    Adequate function of the retina is dependent on proper oxygen supply. In humans, the inner retina is oxygenated via the retinal circulation. We present a method to calculate total retinal oxygen extraction based on measurement of total retinal blood flow using dual-beam bidirectional Doppler optical coherence tomography and measurement of oxygen saturation by spectrophotometry. These measurements were done on 8 healthy subjects while breathing ambient room air and 100% oxygen. Total retinal blood flow was 44.3 ± 9.0 μl/min during baseline and decreased to 18.7 ± 4.2 μl/min during 100% oxygen breathing (P < 0.001) resulting in a pronounced decrease in retinal oxygen extraction from 2.33 ± 0.51 μl(O2)/min to 0.88 ± 0.14 μl(O2)/min during breathing of 100% oxygen. The method presented in this paper may have significant potential to study oxygen metabolism in hypoxic retinal diseases such as diabetic retinopathy.

  20. Retinal oxygen extraction in humans

    PubMed Central

    Werkmeister, René M.; Schmidl, Doreen; Aschinger, Gerold; Doblhoff-Dier, Veronika; Palkovits, Stefan; Wirth, Magdalena; Garhöfer, Gerhard; Linsenmeier, Robert A.; Leitgeb, Rainer A.; Schmetterer, Leopold

    2015-01-01

    Adequate function of the retina is dependent on proper oxygen supply. In humans, the inner retina is oxygenated via the retinal circulation. We present a method to calculate total retinal oxygen extraction based on measurement of total retinal blood flow using dual-beam bidirectional Doppler optical coherence tomography and measurement of oxygen saturation by spectrophotometry. These measurements were done on 8 healthy subjects while breathing ambient room air and 100% oxygen. Total retinal blood flow was 44.3 ± 9.0 μl/min during baseline and decreased to 18.7 ± 4.2 μl/min during 100% oxygen breathing (P < 0.001) resulting in a pronounced decrease in retinal oxygen extraction from 2.33 ± 0.51 μl(O2)/min to 0.88 ± 0.14 μl(O2)/min during breathing of 100% oxygen. The method presented in this paper may have significant potential to study oxygen metabolism in hypoxic retinal diseases such as diabetic retinopathy. PMID:26503332

  1. Equations for calculating hydrogeochemical reactions of minerals and gases such as CO2 at high pressures and temperatures

    NASA Astrophysics Data System (ADS)

    Appelo, C. A. J.; Parkhurst, D. L.; Post, V. E. A.

    2014-01-01

    Calculating the solubility of gases and minerals at the high pressures of carbon capture and storage in geological reservoirs requires an accurate description of the molar volumes of aqueous species and the fugacity coefficients of gases. Existing methods for calculating the molar volumes of aqueous species are limited to a specific concentration matrix (often seawater), have been fit for a limited temperature (below 60 °C) or pressure range, apply only at infinite dilution, or are defined for salts instead of individual ions. A more general and reliable calculation of apparent molar volumes of single ions is presented, based on a modified Redlich-Rosenfeld equation. The modifications consist of (1) using the Born equation to calculate the temperature dependence of the intrinsic volumes, following Helgeson-Kirkham-Flowers (HKF), but with Bradley and Pitzer’s expression for the dielectric permittivity of water, (2) using the pressure dependence of the extended Debye-Hückel equation to constrain the limiting slope of the molar volume with ionic strength, and (3) adopting the convention that the proton has zero volume at all ionic strengths, temperatures and pressures. The modifications substantially reduce the number of fitting parameters, while maintaining or even extending the range of temperature and pressure over which molar volumes can be accurately estimated. The coefficients in the HKF-modified-Redlich-Rosenfeld equation were fitted by least-squares on measured solution densities. The limiting volume and attraction factor in the Van der Waals equation of state can be estimated with the Peng-Robinson approach from the critical temperature, pressure, and acentric factor of a gas. The Van der Waals equation can then be used to determine the fugacity coefficients for pure gases and gases in a mixture, and the solubility of the gas can be calculated from the fugacity, the molar volume in aqueous solution, and the equilibrium constant. The coefficients for the

  2. Feldspathic granulite 79215 - Limitations on T-fo2 conditions and time of metamorphism. [temperature-oxygen fugacity relationship in annealed lunar polymict beccia

    NASA Technical Reports Server (NTRS)

    Mcgee, J. J.; Bence, A. E.; Eichhorn, G.; Schaeffer, O. A.

    1978-01-01

    Feldspathic granulite 79215, an annealed polymict breccia which has a bulk composition between anorthositic gabbro and gabbroic anorthosite, contains numerous oxide complexes in the matrix. An Ar-39-Ar-40 stepwise heating experiment gives a well-defined plateau corresponding to an age of 4.03 + or - 0.02 AE. The polmict character of this breccia and the variability of the complexes suggest that they formed as a consequence of reactions between spinel-rich clasts and matrix under the high-T low-P conditions of an ejecta blanket. The duration of annealing is estimated to have been less than 10 million yr; the absence of a KREEP component may indicate an inhomogeneous distribution of this component at the lunar surface at 4.0 AE.

  3. Mineralogy, Petrology and Oxygen Fugacity of the LaPaz Icefield Lunar Basaltic Meteorites and the Origin of Evolved Lunar Basalts

    NASA Technical Reports Server (NTRS)

    Collins, S. J.; Righter, K.; Brandon, A. D.

    2005-01-01

    LAP 02205 is a 1.2 kg lunar mare basalt meteorite found in the Lap Paz ice field of Antarctica in 2002 [1]. Four similar meteorites were also found within the same region [1] and all five have a combined mass of 1.9 kg (LAP 02224, LAP 02226, LAP 02436 and LAP 03632, hereafter called the LAP meteorites). The LAP meteorites all contain a similar texture, mineral assemblage, and composition. A lunar origin for these samples comes from O isotopic data for LAP 02205 [1], Fe/Mn ratios of pyroxenes [1-5], and the presence of distinct lunar mineralogy such as Fe metal and baddeleyite. The LAP meteorites may represent an area of the Moon, which has never been sampled by Apollo missions, or by other lunar meteorites. The data from this study will be used to compare the LAP meteorites to Apollo mare basalts and lunar basaltic meteorites, and will ultimately help to constrain their origin.

  4. Oxygen Fugacity of the Upper Mantle of Mars. Evidence from the Partitioning Behavior of Vanadium in Y980459 (Y98) and other Olivine-Phyric Shergottites

    NASA Technical Reports Server (NTRS)

    Shearer, C. K.; McKay, G. A.; Papike, J. J.; Karner, J.

    2006-01-01

    Using partitioning behavior of V between olivine and basaltic liquid precisely calibrated for martian basalts, we determined the redox state of primitive (olivine-rich, high Mg#) martian basalts near their liquidus. The combination of oxidation state and incompatible element characteristics determined from early olivine indicates that correlations between fO2 and other geochemical characteristics observed in many martian basalts is also a fundamental characteristic of these primitive magmas. However, our data does not exhibit the range of fO2 observed in these previous studies.. We conclude that the fO2 for the martian upper mantle is approximately IW+1 and is incompatible-element depleted. It seems most likely (although clearly open to interpretation) that these mantle-derived magmas assimilated a more oxidizing (>IW+3), incompatible-element enriched, lower crustal component as they ponded at the base of the martian crust.

  5. Phase relations of a simulated lunar basalt as a function of oxygen fugacity, and their bearing on the petrogenesis of the Apollo 11 basalts

    USGS Publications Warehouse

    Tuthill, R.L.; Sato, M.

    1970-01-01

    A glass of Apollo 11 basalt composition crystallizing at 1 atm at low f{hook}02 showed the following crystallization sequence; ferropseudobrookite at 1210??C, olivine at 1200??C, ilmenite and plagioclase at 1140??C, clinopyroxene at 1113??C. Ferropseudobrookite and olivine have a reaction relation to the melt. This sequence agrees with that assumed on textural grounds for some Apollo 11 basalts. It also indicates that the Apollo 11 basalts cannot have been modified by low-pressure fractionation. ?? 1970.

  6. 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)

  7. Firewood calculator

    SciTech Connect

    Clark, A.; Curtis, A.B.; Darwin, W.N.

    1981-01-01

    Rotating cardboard discs are used to read off total tree or topwood firewood volume (tons or cords) that can be expected from trees of d.b.h. 6 to 24 inches and tree height 10 to 90 feet. One side of the calculator is used for broadleaved species with deliquescent crowns and the other side for braodleaves with excurrent crowns.

  8. Enhanced Shrinkage of Lanthanum Strontium Manganite (La0.90Sr0.10MnO3+δ) Resulting from Thermal and Oxygen Partial Pressure Cycling

    SciTech Connect

    McCarthy, Ben; Pederson, Larry R.; Anderson, Harlan U.; Zhou, Xiao Dong; Singh, Prabhakar; Coffey, Greg W.; Thomsen, Ed C.

    2007-10-01

    Exposure of La0.9Sr0.1MnO3+δ to repeated oxygen partial pressure cycles (air/10 ppm O2) resulted in enhanced densification rates, similar to behavior shown previously due to thermal cycling. Shrinkage rates in the temperature range 700 to 1000oC were orders of magnitude higher than Makipirtti-Meng model estimations based on stepwise isothermal dilatometry results at high temperature. A maximum in enhanced shrinkage due to oxygen partial pressure cycling occurred at 900oC. Shrinkage was greatest when LSM-10 bars that were first equilibrated in air were exposed to gas flows of lower oxygen fugacity than in the reverse direction. The former creates transient cation and oxygen vacancies well above the equilibrium concentration, resulting in enhanced mobility. These vacancies annihilate as Schottky equilibria is re-established, whereas the latter condition does not lead to excess vacancy concentrations.

  9. Is the Neoproterozoic oxygen burst a supercontinent legacy?

    NASA Astrophysics Data System (ADS)

    Macouin, Melina; Roques, Damien; Rousse, Sonia; Ganne, Jerome; Denele, Yoann; Trindade, Ricardo

    2015-09-01

    The Neoproterozoic (1000-542 Myr ago) witnessed the dawn of Earth as we know it with modern-style plate tectonics, high levels of O2 in atmosphere and oceans and a thriving fauna. Yet, the processes leading to the fully oxygenation of the external envelopes, its exact timing and its link with the inner workings of the planet remain poorly understood. In some ways, it is a "chicken and egg" question: did the Neoproterozoic Oxygenation Event (NOE) cause life blooming, low-latitudes glaciations and perturbations in geochemical cycles or is it a consequence of these phenomena? Here, we suggest that the NOE may have been triggered by multi-million years oxic volcanic emissions along a protracted period at the end of the Neoproterozoic when continents were assembled in the Rodinia supercontinent. We report a very oxidized magma source at the upper mantle beneath a ring of subducting margins around Rodinia, and detail here the evidence at the margin of the Arabian shield. We investigate the 780 Ma Biotite and Pink granites and associated rocks of the Socotra Island with rock magnetic and petrographic methods. Magnetic susceptibility and isothermal remanent magnetization acquisitions show that, in these granites, both magnetite and hematite are present. Hematite subdivides magnetite grains into small grains. Magnetite and hematite are found to be primary, and formed at the early magmatic evolution of the granite at very high oxygen fugacity. Massive degassing of these oxidized magmas would reduce the sink for oxygen, and consequently contribute to its rise in the atmosphere with a net O2 flux of at least 2.25 x 107 Tmol. Our conceptual model provides a deep Earth link to the NOE and implies the oxygenation burst has occurred earlier than previously envisaged, paving the way for later changes in the outer envelopes of the planet epitomized on the extreme Neoproterozoic glaciations and the appearance of the first animals.

  10. First-principles calculations of 17O nuclear magnetic resonance chemical shielding in Pb(Zr(1/2)Ti(1/2))O3 and Pb(Mg(1/3)Nb(2/3))O3: linear dependence on transition-metal/oxygen bond lengths.

    PubMed

    Pechkis, Daniel L; Walter, Eric J; Krakauer, Henry

    2011-09-21

    First-principles density functional theory oxygen chemical shift tensors were calculated for A(B,B')O(3) perovskite alloys Pb(Zr(1/2)Ti(1/2))O(3) (PZT) and Pb(Mg(1/3)Nb(2/3))O(3) (PMN). Quantum chemistry methods for embedded clusters and the gauge including projector augmented waves (GIPAW) method [C. J. Pickard and F. Mauri, Phys. Rev. B 63, 245101 (2001)] for periodic boundary conditions were used. Results from both methods are in good agreement for PZT and prototypical perovskites. PMN results were obtained using only GIPAW. Both isotropic δ(iso) and axial δ(ax) chemical shifts were found to vary approximately linearly as a function of the nearest-distance transition-metal/oxygen bond length, r(s). Using these results, we argue against Ti clustering in PZT, as conjectured from recent (17)O NMR magic-angle-spinning measurements. Our findings indicate that (17)O NMR measurements, coupled with first-principles calculations, can be an important probe of local structure in complex perovskite solid solutions.

  11. THE INDOOR FUGACITY MODEL

    EPA Science Inventory

    Dermal and non-dietary pathways are potentially significant exposure pathways to pesticides used in the home. The exposure pathways include dermal contact through the hands and skin, ingestion from hand to mouth activities, ingestion through contact with toys and other items, ...

  12. Density functional calculations of (55)Mn, (14)N and (13)C electron paramagnetic resonance parameters support an energetically feasible model system for the S(2) state of the oxygen-evolving complex of photosystem II.

    PubMed

    Schinzel, Sandra; Schraut, Johannes; Arbuznikov, Alexei V; Siegbahn, Per E M; Kaupp, Martin

    2010-09-10

    Metal and ligand hyperfine couplings of a previously suggested, energetically feasible Mn(4)Ca model cluster (SG2009(-1)) for the S(2) state of the oxygen-evolving complex (OEC) of photosystem II (PSII) have been studied by broken-symmetry density functional methods and compared with other suggested structural and spectroscopic models. This was carried out explicitly for different spin-coupling patterns of the S=1/2 ground state of the Mn(III)(Mn(IV))(3) cluster. By applying spin-projection techniques and a scaling of the manganese hyperfine couplings, computation of the hyperfine and nuclear quadrupole coupling parameters allows a direct evaluation of the proposed models in comparison with data obtained from the simulation of EPR, ENDOR, and ESEEM spectra. The computation of (55)Mn hyperfine couplings (HFCs) for SG2009(-1) gives excellent agreement with experiment. However, at the current level of spin projection, the (55)Mn HFCs do not appear sufficiently accurate to distinguish between different structural models. Yet, of all the models studied, SG2009(-1) is the only one with the Mn(III) site at the Mn(C) center, which is coordinated by histidine (D1-His332). The computed histidine (14)N HFC anisotropy for SG2009(-1) gives much better agreement with ESEEM data than the other models, in which Mn(C) is an Mn(IV) site, thus supporting the validity of the model. The (13)C HFCs of various carboxylates have been compared with (13)C ENDOR data for PSII preparations with (13)C-labelled alanine.

  13. Home Oxygen Therapy

    MedlinePlus

    ... oxygen is rarely delivered in the older large, steel gas cylinders any longer since frequent and costly ... just like the compressed oxygen in the older steel cylinders. An important advantage of liquid oxygen is ...

  14. A new oxygen barometer for solar system basaltic glasses based on vanadium valence

    SciTech Connect

    Karner, J.M.; Sutton, S.R.; Papike, J.J.; Delaney, J.S.; Shearer, C.K.; Newville, M.; Eng, P.; Rivers, M.; Dyar, M.D.

    2004-05-10

    An oxybarometer based on vanadium valence and applicable to basaltic glasses covers eight orders of magnitude in oxygen fugacity. The determination of oxidation conditions for basaltic magmas derived by the melting of planetary mantles is critical to our understanding of the nature and evolution of planetary interiors. Yet, these determinations are compromised in terrestrial and especially extraterrestrial basalts by our analytical and computational methods for estimating oxygen fugacity (fO{sub 2}). For example, mineralogical barometers (1, 2) can be reduced in effectiveness by subsolidus re-equilibration of mineral assemblages, inversion of mineralogical data to melt characteristics, and deviations of the natural mineral compositions from ideal thermodynamic parameters. Likewise, techniques to estimate fO{sub 2} based on the valence state of Fe (i.e. Fe{sup 3+}/Fe{sup 2+}) are ineffective for materials that crystallized at or below the IW buffer, and only contain Fe{sup 2+} and Fe{sup 0} (3). For these reasons, we have developed an oxybarometer based on the valence state of vanadium in basaltic glasses. This oxybarometer has enormous potential because (1) V valence is measured in basaltic glasses that have been quenched at near liquidus temperatures, thereby recording magmatic fO{sub 2} conditions, and (2) V is a multivalent element, existing as V{sup 2+}, V{sup 3+}, V{sup 4+}, and V{sup 5+}, thus allowing for applicability over a range of redox conditions from the most reduced materials in the solar system, (e.g. calcium aluminum rich inclusions in chondritic meteorites [4]) to the most oxidized terrestrial magmas (this work).

  15. Oxygen delivery from red cells.

    PubMed Central

    Clark, A; Federspiel, W J; Clark, P A; Cokelet, G R

    1985-01-01

    This paper deals with the theoretical analysis of the unloading of oxygen from a red cell. A scale analysis of the governing transport equations shows that the solutions have a boundary layer structure near the red-cell membrane. The boundary layer is a region of chemical nonequilibrium, and it owes its existence to the fact that the kinetic time scales are shorter than the diffusion time scales in the red cell. The presence of the boundary layer allows an analytical solution to be obtained by the method of matched asymptotic expansions. A very useful result from the analysis is a simple, lumped-parameter description of the oxygen delivery from a red cell. The accuracy of the lumped-parameter description has been verified by comparing its predictions with results obtained by numerical integration of the full equations for a one-dimensional slab. As an application, we calculate minimum oxygen unloading times for red cells. PMID:3978198

  16. Oxygen Michaelis constants for tyrosinase.

    PubMed Central

    Rodríguez-López, J N; Ros, J R; Varón, R; García-Cánovas, F

    1993-01-01

    The Michaelis constant of tyrosinase for oxygen in the presence of monophenols and o-diphenols, which generate a cyclizable o-quinone, has been studied. This constant depends on the nature of the monophenol and o-diphenol and is always lower in the presence of the former than of the latter. From the mechanism proposed for tyrosinase and from its kinetic analysis [Rodríguez-López, J. N., Tudela, J., Varón, R., García-Carmona, F. and García-Cánovas, F. (1992) J. Biol. Chem. 267, 3801-3810] a quantitative ratio has been established between the Michaelis constants for oxygen in the presence of monophenols and their o-diphenols. This ratio is used for the determination of the Michaelis constant for oxygen with monophenols when its value cannot be calculated experimentally. PMID:8352753

  17. A calcium oxygen secondary battery

    NASA Astrophysics Data System (ADS)

    Pujare, Nirupama U.; Semkow, Krystyna W.; Sammells, Anthony F.

    1988-01-01

    This paper describes a high-temperature electrochemically-reversible calcium-oxygen cell in which the negative electroactive material consists of a calcium-silicon alloy contained within an expanded stainless steel electrode assembly immersed into a binary molten salt CaO-CaCl2 (mp 593 C). The empirical electrochemistry occurring upon electrochemical cycling is: 2CaSi + 1/2 O2(air) going to CaO + CaSi2, with oxygen being reversibly mediated to the binary molten salt via the oxygen vacancy conducting solid electrolyte; charge-discharge curves at 850 C clearly demonstrated voltage plateaus associated with the reversible formation of CaSi and CaSi2. If unit activity Ca were used as the negative electroactive material, the cell thermodynamic open-circuit voltage at 850 C is expected to be about 2.28 V. The theoretical energy density for this system calculates to 985 W h/lb.

  18. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. Thermogravimetric analysis (TGA) was carried out on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} to investigate oxygen deficiency ({delta}) of the sample. The TGA was performed in a controlled atmosphere using oxygen, argon, carbon monoxide and carbon dioxide with adjustable gas flow rates. In this experiment, the weight loss and gain of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} was directly measured by TGA. The weight change of the sample was evaluated at between 600 and 1250 C in air or 1000 C as a function of oxygen partial pressure. The oxygen deficiencies calculated from TGA data as a function of oxygen activity and temperature will be estimated and compared with that from neutron diffraction measurement in air. The LSFT and LSFT/CGO membranes were fabricated from the powder obtained from Praxair Specialty Ceramics. The sintered membranes were subjected to microstructure analysis and hardness analysis. The LSFT membrane is composed of fine grains with two kinds of grain morphology. The grain size distribution was characterized using image analysis. In LSFT/CGO membrane a lot of grain pullout was observed from the less dense, porous phase. The hardness of the LSFT and dual phase membranes were studied at various loads. The hardness values obtained from the cross section of the membranes were also compared to that of the values obtained from the surface. An electrochemical cell has been designed and built for measurements of the Seebeck coefficient as a function of temperature and pressure. Measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} as a function of temperature an oxygen partial pressure are reported. Further analysis of the dilatometry data obtained previously is presented. A series of isotope transients

  19. 40 CFR 1065.850 - Calculations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Calculations. 1065.850 Section 1065.850 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Testing With Oxygenated Fuels § 1065.850 Calculations. Use the...

  20. 40 CFR 1065.850 - Calculations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Calculations. 1065.850 Section 1065.850 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Testing With Oxygenated Fuels § 1065.850 Calculations. Use the...

  1. 40 CFR 1065.850 - Calculations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Calculations. 1065.850 Section 1065.850 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Testing With Oxygenated Fuels § 1065.850 Calculations. Use the...

  2. 40 CFR 1065.850 - Calculations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Calculations. 1065.850 Section 1065.850 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Testing With Oxygenated Fuels § 1065.850 Calculations. Use the...

  3. 40 CFR 1065.850 - Calculations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Calculations. 1065.850 Section 1065.850 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Testing With Oxygenated Fuels § 1065.850 Calculations. Use the...

  4. 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.

  5. Alcohol Calorie Calculator

    MedlinePlus

    ... Alcohol Calorie Calculator Weekly Total 0 Calories Alcohol Calorie Calculator Find out the number of beer and ... Calories College Alcohol Policies Interactive Body Calculators Alcohol Calorie Calculator Alcohol Cost Calculator Alcohol BAC Calculator Alcohol ...

  6. 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.

  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. 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.

  9. 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.

  10. 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.

  11. Benefits of oxygen incorporation in atomic laminates

    NASA Astrophysics Data System (ADS)

    Dahlqvist, Martin

    2016-04-01

    Atomic laminates such as MAX phases benefit from the addition of oxygen in many ways, from the formation of a protective oxide surface layer with self-healing capabilities when cracks form to the tuning of anisotropic conductivity. In this paper oxygen incorporation and vacancy formation in M 2AlC (M  =  Ti, V, Cr) MAX phases have been studied using first-principles calculations where the focus is on phase stability and electronic structure for different oxygen and/or vacancy configurations. Oxygen prefers different lattice sites depending on M-element and this can be correlated to the number of available non-bonding M d-electrons. In Ti2AlC, oxygen substitutes carbon while in Cr2AlC it is located interstitially within the Al-layer. I predict that oxygen incorporation in Ti2AlC stabilizes the material, which explains the experimentally observed 12.5 at% oxygen (x  =  0.5) in Ti2Al(C1-x O x ). In addition, it is also possible to use oxygen to stabilize the hypothetical Zr2AlC and Hf2AlC. Hence, oxygen incorporation may be beneficial in many ways. Not only can it make a material more stable, but it also can act as a reservoir for internal self-healing with shorter diffusion paths.

  12. 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.

  13. Program developed for CO{sub 2} system calculations

    SciTech Connect

    Lewis, E.; Wallace, D.; Allison, L.J.

    1998-02-01

    The program CO2SYS performs calculations relating parameters of the carbon dioxide (CO{sub 2}) system in seawater and freshwater. The program uses two of the four measurable parameters of the CO{sub 2} system [total alkalinity (TA), total inorganic CO{sub 2} (TCO{sub 2}), pH, and either fugacity (fCO{sub 2}) or partial pressure of CO{sub 2} (pCO{sub 2})] to calculate the other two parameters at a set of input conditions (temperature and pressure) and a set of output conditions chosen by the user. It replaces and extends the programs CO2SYSTM.EXE, FCO2TCO2.EXE, PHTCO2.EXE, and CO2BTCH.EXE, which were released in May 1995. It may be run in single-input mode or batch-input mode and has a variety of options for the various constants and parameters used. An on-screen information section is available that includes documentation on various topics relevant to the program. This program may be run on any 80 x 86 computer equipped with the DOS operating system by simply typing CO2SYS at the prompt after loading the executable file CO2SYS.EXE.

  14. 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.

  15. Modelling Hydrogen Reduction and Hydrodeoxygenation of Oxygenates

    SciTech Connect

    Zhao, Y.; Xu, Q.; Cheah, S.

    2013-01-01

    Based on Density Functional Theory (DFT) simulations, we have studied the reduction of nickel oxide and biomass derived oxygenates (catechol, guaiacol, etc.) in hydrogen. Both the kinetic barrier and thermodynamic favorability are calculated with respect to the modeled reaction pathways. In early-stage reduction of the NiO(100) surface by hydrogen, the pull-off of the surface oxygen atom and simultaneous activation of the nearby Ni atoms coordinately dissociate the hydrogen molecules so that a water molecule can be formed, leaving an oxygen vacancy on the surface. In hydrogen reaction with oxygenates catalyzed by transition metals, hydrogenation of the aromatic carbon ring normally dominates. However, selective deoxygenation is of particular interest for practical application such as biofuel conversion. Our modeling shows that doping of the transition metal catalysts can change the orientation of oxygenates adsorbed on metal surfaces. The correlation between the selectivity of reaction and the orientation of adsorption are discussed.

  16. 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 ...

  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. 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.

  19. 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.

  20. Atomic oxygen exposure of LDEF experiment trays

    NASA Technical Reports Server (NTRS)

    Bourassa, R. J.; Gillis, J. R.

    1992-01-01

    Atomic oxygen exposures were determined analytically for rows, longerons, and end bays of the Long Duration Exposure Facility (LDEF). The calculations are based on an analytical model that accounts for the effects of thermal molecular velocity, atmospheric temperature, number density, spacecraft velocity, incidence angle, and atmospheric rotation on atomic oxygen flux. Results incorporate variations in solar activity, geomagnetic index, and orbital parameters occurring over the 6-year flight of the spacecraft. To facilitate use of the data, both detailed tabulations and summary charts for atomic oxygen fluences are presented.

  1. 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.

  2. 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.

  3. 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.

  4. 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 ...

  5. Assessment of Industry-Induced Urban Human Health Risks Related to Benzo[a]pyrene based on a Multimedia Fugacity Model: Case Study of Nanjing, China

    PubMed Central

    Xu, Linyu; Song, Huimin; Wang, Yan; Yin, Hao

    2015-01-01

    Large amounts of organic pollutants emitted from industries have accumulated and caused serious human health risks, especially in urban areas with rapid industrialization. This paper focused on the carcinogen benzo[a]pyrene (BaP) from industrial effluent and gaseous emissions, and established a multi-pathway exposure model based on a Level IV multimedia fugacity model to analyze the human health risks in a city that has undergone rapid industrialization. In this study, GIS tools combined with land-use data was introduced to analyze smaller spatial scales so as to enhance the spatial resolution of the results. An uncertainty analysis using a Monte Carlo simulation was also conducted to illustrate the rationale of the probabilistic assessment mode rather than deterministic assessment. Finally, the results of the case study in Nanjing, China indicated the annual average human cancer risk induced by local industrial emissions during 2002–2008 (lowest at 1.99×10–6 in 2008 and highest at 3.34×10–6 in 2004), which was lower than the USEPA prescriptive level (1×10–6–1×10–4) but cannot be neglected in the long term.The study results could not only instruct the BaP health risk management but also help future health risk prediction and control. PMID:26035663

  6. Analyzing sediment dissolved oxygen based on microprofile modeling.

    PubMed

    Wang, Chao; Shan, Baoqing; Zhang, Hong; Rong, Nan

    2014-09-01

    Sediment plays a key role in controlling the oxygen demand of aquatic systems. The reaction rate, penetration depth, and flux across the sediment-water interface (SWI) are important factors in sediment oxygen consumption. However, there were few methods to collect these data until recently. In this study, methods were developed to simulate the oxygen microprofile and calculate the sediment oxygen consumption rate, oxygen penetration depth, and oxygen flux across the SWI. We constructed a sediment oxygen measuring system using an oxygen microelectrode and a control device. The simulation equations were derived from both zero and first-order kinetic models, while the penetration depth and the oxygen flux were calculated from the simulation results. The method was tested on four prepared sediment samples. Decreases in dissolved oxygen in surface sediment were clearly detected by the microelectrode. The modeled data were a good fit for the observed data (R (2) > 0.95), and zero-order kinetics were more suitable than first-order kinetics. The values for penetration depth (1.3-3.9 mm) and oxygen fluxes (0.061-0.114 mg/cm(2)/day) calculated by our methods are comparable with those from other studies.

  7. The system Fe-Si-O: Oxygen buffer calibrations to 1,500K

    NASA Astrophysics Data System (ADS)

    Myers, J.; Eugster, H. P.

    1983-03-01

    The five solid-phase oxygen buffers of the system Fe-Si-O, iron-wuestite (IW), wuestite-magnetite (WM), magnetite-hematite (MH), quartz-iron-fayalite (QIF) and fayalite-magnetite-quartz (FMQ) have been recalibrated at 1 atm pressure and temperatures from 800° 1,300° C, using a thermogravimetric gas mixing furnace. The oxygen fugacity, f_{{text{O}}_{text{2}} } was measured with a CaO-doped ZrO2 electrode. Measurements were made also for wuestite solid solutions in order to determine the redox behavior of wuestites with O/Fe ratios varying from 1.05 to 1.17. For FMQ, additional determinations were carried out at 1 kb over a temperature range of 600° to 800° C, using a modified Shaw membrane. Results agree reasonably well with published data and extrapolations. The reaction parameters K, Δ G {r/o}, Δ H {r/o}, and Δ S {r/o}were calculated from the following log f_{{text{O}}_{text{2}} }/ T relations (T in K): 410_2004_Article_BF00371177_TeX2GIFE1.gif begin{gathered} {text{IW }}log f_{{text{O}}_{text{2}} } = - 26,834.7/T + 6.471left( { ± 0.058} right) \\ {text{ }}left( {{text{800}} - 1,260{text{ C}}} right), \\ {text{WM }}log f_{{text{O}}_{text{2}} } = - 36,951.3/T + 16.092left( { ± 0.045} right) \\ {text{ }}left( {{text{1,000}} - 1,300{text{ C}}} right), \\ {text{MH }}log f_{{text{O}}_{text{2}} } = - 23,847.6/T + 13.480left( { ± 0.055} right) \\ {text{ }}left( {{text{1,040}} - 1,270{text{ C}}} right), \\ {text{QIF }}log f_{{text{O}}_{text{2}} } = - 27,517.5/T + 6.396left( { ± 0.049} right) \\ {text{ }}left( {{text{960}} - 1,140{text{ C}}} right), \\ {text{FMQ }}log f_{{text{O}}_{text{2}} } = - 24,441.9/T + 8.290left( { ± 0.167} right) \\ {text{ }}left( {{text{600}} - 1,140{text{ C}}} right). \\ These experimentally determined reaction parameters were combined with published 298 K data to determine the parameters Gf, Hf, and Sf for the phases wuestite, magnetite, hematite, and fayalite from 298 K to the temperatures of the experiments. The T

  8. Operational Considerations for Oxygen Flammability Risks: Concentrated Oxygen Diffusion and Permeation Behaviors

    NASA Technical Reports Server (NTRS)

    Harper, Susana; Smith, Sarah; Juarez, Alfredo; Hirsch, David

    2010-01-01

    Increased human spaceflight operations utilize oxygen concentrations that are frequently varied with use of concentrations up to 100 percent oxygen. Even after exiting a higher percentage oxygen environment, high oxygen concentrations can still be maintained due to material saturation and oxygen entrapment between barrier materials. This paper examines the material flammability concerns that arise from changing oxygen environments during spaceflight operations. We examine the time required for common spacecraft and spacesuit materials exposed to oxygen to return to reduced ignitability and flammability once removed from the increased concentration. Various common spacecraft materials were considered: spacecraft cabin environment foams, Extra Vehicular Mobility Unit materials and foams, Advanced Crew Escape Suit materials, and other materials of interest such as Cotton, Nomex^ HT90-40, and Tiburon Surgical Drape. This paper presents calculated diffusion coefficients derived from experimentally obtained oxygen transmission rates for the tested materials and the analytically derived times necessary for reduced flammability to be achieved based on NASA flammability criteria. Oxygen material saturation and entrapment scenarios are examined. Experimental verification data on oxygen diffusion in saturation scenarios are also presented and discussed. We examine how to use obtained data to address flammability concerns during operational planning to reduce the likelihood of fires while improving efficiency for procedures.

  9. Modeling Oxygen Transport in the Human Placenta

    NASA Astrophysics Data System (ADS)

    Serov, Alexander; Filoche, Marcel; Salafia, Carolyn; Grebenkov, Denis

    Efficient functioning of the human placenta is crucial for the favorable pregnancy outcome. We construct a 3D model of oxygen transport in the placenta based on its histological cross-sections. The model accounts for both diffusion and convention of oxygen in the intervillous space and allows one to estimate oxygen uptake of a placentone. We demonstrate the existence of an optimal villi density maximizing the uptake and explain it as a trade-off between the incoming oxygen flow and the absorbing villous surface. Calculations performed for arbitrary shapes of fetal villi show that only two geometrical characteristics - villi density and the effective villi radius - are required to predict fetal oxygen uptake. Two combinations of physiological parameters that determine oxygen uptake are also identified: maximal oxygen inflow of a placentone and the Damköhler number. An automatic image analysis method is developed and applied to 22 healthy placental cross-sections demonstrating that villi density of a healthy human placenta lies within 10% of the optimal value, while overall geometry efficiency is rather low (around 30-40%). In a perspective, the model can constitute the base of a reliable tool of post partum oxygen exchange efficiency assessment in the human placenta. Also affiliated with Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095, USA.

  10. 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.

  11. 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.

  12. 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.

  13. Enzymatic Glucose Sensor Compensation for Variations in Ambient Oxygen Concentration

    PubMed Central

    Collier, Bradley B.; McShane, Michael J.

    2014-01-01

    Due to the increasing prevalence of diabetes, research toward painless glucose sensing continues. Oxygen sensitive phosphors with glucose oxidase (GOx) can be used to determine glucose levels indirectly by monitoring oxygen consumption. This is an attractive combination because of its speed and specificity. Packaging these molecules together in “smart materials” for implantation will enable non-invasive glucose monitoring. As glucose levels increase, oxygen levels decrease; consequently, the luminescence intensity and lifetime of the phosphor increase. Although the response of the sensor is dependent on glucose concentration, the ambient oxygen concentration also plays a key role. This could lead to inaccurate glucose readings and increase the risk of hyper- or hypoglycemia. To mitigate this risk, the dependence of hydrogel glucose sensor response on oxygen levels was investigated and compensation methods explored. Sensors were calibrated at different oxygen concentrations using a single generic logistic equation, such that trends in oxygen-dependence were determined as varying parameters in the equation. Each parameter was found to be a function of oxygen concentration, such that the correct glucose calibration equation can be calculated if the oxygen level is known. Accuracy of compensation will be determined by developing an overall calibration, using both glucose and oxygen sensors in parallel, correcting for oxygen fluctuations in real time by intentionally varying oxygen, and calculating the error in actual and predicted glucose levels. While this method was developed for compensation of enzymatic glucose sensors, in principle it can also be implemented with other kinds of sensors utilizing oxidases. PMID:26257458

  14. HENRY'S LAW CALCULATOR

    EPA Science Inventory

    On-Site was developed to provide modelers and model reviewers with prepackaged tools ("calculators") for performing site assessment calculations. The philosophy behind OnSite is that the convenience of the prepackaged calculators helps provide consistency for simple calculations,...

  15. Diffusion of oxygen in cork.

    PubMed

    Lequin, Sonia; Chassagne, David; Karbowiak, Thomas; Simon, Jean-Marc; Paulin, Christian; Bellat, Jean-Pierre

    2012-04-04

    This work reports measurements of effective oxygen diffusion coefficient in raw cork. Kinetics of oxygen transfer through cork is studied at 298 K thanks to a homemade manometric device composed of two gas compartments separated by a cork wafer sample. The first compartment contains oxygen, whereas the second one is kept under dynamic vacuum. The pressure decrease in the first compartment is recorded as a function of time. The effective diffusion coefficient D(eff) is obtained by applying Fick's law to transient state using a numerical method based on finite differences. An analytical model derived from Fick's law applied to steady state is also proposed. Results given by these two methods are in close agreement with each other. The harmonic average of the effective diffusion coefficients obtained from the distribution of 15 cork wafers of 3 mm thickness is 1.1 × 10(-9) m(2) s(-1) with a large distribution over four decades. The statistical analysis of the Gaussian distribution obtained on a 3 mm cork wafer is extrapolated to a 48 mm cork wafer, which length corresponds to a full cork stopper. In this case, the probability density distribution gives a mean value of D(eff) equal to 1.6 × 10(-9) m(2) s(-1). This result shows that it is possible to obtain the effective diffusion coefficient of oxygen through cork from short time (few days) measurements performed on a thin cork wafer, whereas months are required to obtain the diffusion coefficient for a full cork stopper. Permeability and oxygen transfer rate are also calculated for comparison with data from other studies.

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. Silicon in Mars' Core: A Prediction Based on Mars Model Using Nitrogen and Oxygen Isotopes in SNC Meteorites

    NASA Technical Reports Server (NTRS)

    Mohapatra, R. K.; Murty, S. V. S.

    2002-01-01

    Chemical and (oxygen) isotopic compositions of SNC meteorites have been used by a number of workers to infer the nature of precursor materials for the accretion of Mars. The idea that chondritic materials played a key role in the formation of Mars has been the central assumption in these works. Wanke and Dreibus have proposed a mixture of two types of chondritic materials, differing in oxygen fugacity but having CI type bulk chemical composition for the nonvolatile elements, for Mars' precursor. But a number of studies based on high pressure and temperature melting experiments do not favor a CI type bulk planet composition for Mars, as it predicts a bulk planet Fe/Si ratio much higher than that reported from the recent Pathfinder data. Oxygen forms the bulk of Mars (approximately 40% by wt.) and might provide clues to the type of materials that formed Mars. But models based on the oxygen isotopic compositions of SNC meteorites predict three different mixtures of precursor materials for Mars: 90% H + 10% CM, 85% H + 11% CV + 4% CI and 45% EH + 55% H. As each of these models has been shown to be consistent with the bulk geophysical properties (such as mean density, and moment of inertia factor) of Mars, the nature of the material that accreted to form Mars remains ambiguous.

  2. 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.

  3. 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.

  4. Integrated turbomachine oxygen plant

    SciTech Connect

    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.

  5. 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.

  6. 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.

  7. 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.

  8. Oxidation-Reduction Calculations in the Biochemistry Course

    ERIC Educational Resources Information Center

    Feinman, Richard D.

    2004-01-01

    Redox calculations have the potential to reinforce important concepts in bioenergetics. The intermediacy of the NAD[superscript +]/NADH couple in the oxidation of food by oxygen, for example, can be brought out by such calculations. In practice, students have great difficulty and, even when adept at the calculations, frequently do not understand…

  9. 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.

  10. 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).

  11. 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.

  12. Uncertainty analysis using a fugacity-based multimedia mass-balance model: application of the updated EQC model to decamethylcyclopentasiloxane (D5).

    PubMed

    Kim, Jaeshin; Powell, David E; Hughes, Lauren; Mackay, Don

    2013-10-01

    The EQuilibrium Criterion (EQC) model developed and published in 1996 was recently revised to include improved treatment of input partitioning and reactivity data, temperature dependence and an easier sensitivity and uncertainty analysis. This New EQC model was used to evaluate the multimedia, fugacity-based fate of decamethylcyclopentasiloxane (D5; CAS No. 541-02-6) in the environment over a temperature range of 1-25°C. In addition, Monte Carlo uncertainty analysis was used to quantitatively determine the influence of temperature and input partitioning and reactivity data on the behavior of D5 under various emission scenarios. Results indicated that emission mode was the most influential factor determining the fate and distribution of D5 in the model environment. When emitted to air and soil, D5 partitioned to and remained in the air compartment where rates of removal from degradation and advection processes were relatively rapid. In contrast, D5 emitted to water resulted in a substantial mass fraction of D5 being accumulated in the sediment compartment, where rates of removal from degradation and advection processes were slow. The mass distributions and fate of D5 in the model environment were strongly influenced by multiple input parameters, including temperature, the mode of emission (especially emission rate to water), KOC and half-life in air. As temperature decreased from 25°C to 1°C, KOC and half-life in air became increasingly more influential such that the mass distribution of D5 increased in air and decreased in sediment, resulting in decreased overall persistence.

  13. Rat splanchnic net oxygen consumption, energy implications.

    PubMed Central

    Casado, J; Fernández-López, J A; Esteve, M; Rafecas, I; Argilés, J M; Alemany, M

    1990-01-01

    1. The blood flow, PO2, pH and PCO2 have been estimated in portal and suprahepatic veins as well as in hepatic artery of fed and overnight starved rats given an oral glucose load. From these data the net intestinal, hepatic and splanchnic balances for oxygen and bicarbonate were calculated. The oxygen consumption of the intact animal has also been measured under comparable conditions. 2. The direct utilization of oxygen balances as energy equivalents when establishing the contribution of energy metabolism of liver and intestine to the overall energy expenses of the rat, has been found to be incorrect, since it incorporates the intrinsic error of interorgan proton transfer through bicarbonate. Liver and intestine produced high net bicarbonate balances in all situations tested, implying the elimination (by means of oxidative pathways, i.e. consuming additional oxygen) of high amounts of H+ generated with bicarbonate. The equivalence in energy output of the oxygen balances was then corrected for bicarbonate production to 11-54% lower values. 3. Intestine and liver consume a high proportion of available oxygen, about one-half in basal (fed or starved) conditions and about one-third after gavage, the intestine consumption being about 15% in all situations tested and the liver decreasing its oxygen consumption with gavage. PMID:2129230

  14. K-alpha X-rays from cosmic-ray oxygen. [subrelativistic interstellar oxygen ions

    NASA Technical Reports Server (NTRS)

    Pravdo, S. H.; Boldt, E. A.

    1975-01-01

    Equilibrium charge fractions are calculated for subrelativistic cosmic-ray oxygen ions in the interstellar medium. These are used to determine the expected flux of K-alpha rays arising from atomic processes for a number of different postulated interstellar oxygen spectra. Relation of these results to the diffuse X-ray background measured at the appropriate energy (about 0.6 keV) suggests an observable broadened line feature.

  15. 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.

  16. Oxygen isotope fractionation in double carbonates.

    PubMed

    Zheng, Yong-Fei; Böttcher, Michael E

    2016-01-01

    Oxygen isotope fractionations in double carbonates of different crystal structures were calculated by the increment method. Synthesis experiments were performed at 60 °C and 100 °C to determine oxygen and carbon isotope fractionations involving PbMg[CO3]2. The calculations suggest that the double carbonates of calcite structure are systematically enriched in (18)O relative to those of aragonite and mixture structures. Internally consistent oxygen isotope fractionation factors are obtained for these minerals with respect to quartz, calcite and water at a temperature range of 0-1200 °C. The calculated fractionation factors for double carbonate-water systems are generally consistent with the data available from laboratory experiments. The experimentally determined fractionation factors for PbMg[CO3]2, BaMg[CO3]2 and CaMg[CO3]2 against H2O not only fall between fractionation factors involving pure carbonate end-members but are also close to the calculated fractionation factors. In contrast, experimentally determined carbon isotope fractionation factors between PbMg[CO3]2 and CO2 are much closer to theoretical predictions for the cerussite-CO2 system than for the magnesite-CO2 system, similar to the fractionation behavior for BaMg[CO3]2. Therefore, the combined theoretical and experimental results provide insights into the effects of crystal structure and exchange kinetics on oxygen isotope partitioning in double carbonates.

  17. Visible light optical coherence tomography measure retinal oxygen metabolic response to systemic oxygenation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Yi, Ji; Liu, Wenzhong; Chen, Siyu; Backman, Vadim; Sheibani, Nader; Sorenson, Christine M.; Fawzi, Amani A.; Linsenmeier, Robert A.; Zhang, Hao F.

    2016-03-01

    The lack of capability to quantify oxygen metabolism noninvasively impedes both fundamental investigation and clinical diagnosis of a wide spectrum of diseases including all the major blinding diseases such as age-related macular degeneration, diabetic retinopathy, and glaucoma. Using visible light optical coherence tomography (vis-OCT), we demonstrated accurate and robust measurement of retinal oxygen metabolic rate (rMRO2) noninvasively in rat eyes. The rMRO2 was calculated by concurrent measurement of blood flow and blood oxygen saturation (sO2). Blood flow was calculated by the principle of Doppler optical coherence tomography, where the phase shift between two closely spaced A-lines measures the axial velocity. The distinct optical absorption spectra of oxy- and deoxy-hemoglobin provided the contrast for sO2 measurement, combined with the spectroscopic analysis of vis-OCT signal within the blood vessels. We continuously monitored the regulatory response of oxygen consumption to a progressive hypoxic challenge. We found that both oxygen delivery, and rMRO2 increased from the highly regulated retinal circulation (RC) under hypoxia, by 0.28+/-0.08 μL/min (p<0.001), and 0.20+/-0.04 μL/min (p<0.001) per 100 mmHg systemic pO2 reduction, respectively. The increased oxygen extraction compensated for the deficient oxygen supply from the poorly regulated choroidal circulation (CC).

  18. 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.

  19. 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.

  20. 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.

  1. Estimation of air concentrations and profiles for polychlorinated dibenzo-p-dioxins and dibenzofurans from calculated vegetation-air partition coefficients

    SciTech Connect

    Kjeller, L.O.; Rappe, C.; Jones, K.C.

    1995-12-31

    Air concentrations of vapor and particulate phase polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are predicted by use of calculated plant-air partition coefficients. The plant-air interaction is reduced to an octanol-air distribution at equilibrium. Partition coefficients are deduced from the fugacity approach and calculated from congener group average data of solubility, vapor pressure and octanol-water partition coefficient. Calculated partition coefficients were used for prediction of the PCDD/F levels and congener profile in air from archived herbage collected pre- and post-1940. Before 1940 the air had a fly ash or combustion derived PCDD/F composition. After 1940 Hp and OCDD/F are superimposed on the combustion pattern, reflection of their release from the extensive use of polychlorinated compounds, notably penta chlorophenol, but also related compounds.

  2. The effect of colic on oxygen extraction in horses.

    PubMed

    Cambier, C; Wierinckx, M; Grulke, S; Clerbaux, T; Serteyn, D; Detry, B; Liardet, M-P; Frans, A; Gustin, P

    2008-01-01

    Blood oxygen transport and oxygen extraction were assessed in horses with colic. A gravity score (GS) ranging from 1 to 3 was attributed to each colic case with healthy horses used as controls. Jugular venous and carotid arterial blood samples were collected and concentrations of 2,3-diphosphoglycerate, adenosine triphosphate, inorganic phosphate and chloride were determined. pH and partial pressures of carbon dioxide (PCO(2)), and oxygen (PO(2)) were also measured. Oxygen equilibrium curves (OEC) were constructed under standard conditions and oxygen extraction ratios calculated. Haemoglobin oxygen affinity measured under standard conditions (P50(std)) was unchanged in colic horses compared with healthy controls. Horses with the highest GS, i.e. 3 had lower blood pH values than healthy animals. Arterial and venous partial pressures of oxygen at 50% haemoglobin saturation (P50(a) and P50(v)) were significantly higher in horses suffering from colic (GS=3) than in healthy horses. The oxygen extraction ratio was also significantly increased in colic horses with a GS of 3. A rise in the oxygen extraction ratio detected in the most severely affected animals seemed to reflect the compensatory properties of the oxygen transport system where extraction of oxygen from the blood increases when systemic oxygen delivery decreases, as might be anticipated in horses with colic.

  3. Distillation Calculations with a Programmable Calculator.

    ERIC Educational Resources Information Center

    Walker, Charles A.; Halpern, Bret L.

    1983-01-01

    Describes a three-step approach for teaching multicomponent distillation to undergraduates, emphasizing patterns of distribution as an aid to understanding the separation processes. Indicates that the second step can be carried out by programmable calculators. (A more complete set of programs for additional calculations is available from the…

  4. 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

  5. Oxygen Transport in Melts Based on V2O5

    NASA Astrophysics Data System (ADS)

    Klimashin, Anton; Belousov, Valery

    2016-02-01

    An oxygen ion transport model was developed for oxide melts based on V2O5. Within the framework of this model, the values of the parabolic rate constant of catastrophic oxidation of V2O5-deposited copper and the oxygen flux through the slags based on molten V2O5 were calculated and compared with experimental data. The calculated and experimental values are of the same order of magnitude which shows an adequacy of the model.

  6. 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.

  7. 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.

  8. Programmable calculator stress analysis

    SciTech Connect

    Van Gulick, L.A.

    1983-01-01

    Advanced programmable alphanumeric calculators are well suited for closed-form calculation of pressure-vessel stresses. They offer adequate computing power, portability, special programming features, and simple interactive execution procedures. Representative programs that demonstrate calculator capabilities are presented. Problems treated are stress and strength calculations in thick-walled pressure vessels and the computation of stresses near head/pressure-vessel junctures.

  9. Magnetism in Lithium–Oxygen Discharge Product

    SciTech Connect

    Lu, Jun; Jung, Hun-Ji; Lau, Kah Chun; Zhang, Zhengcheng; Schlueter, John A.; Du, Peng; Assary, Rajeev S.; Greeley, Jeffrey P.; Ferguson, Glen A.; Wang, Hsien-Hau; Hassoun, Jusef; Iddir, Hakim; Zhou, Jigang; Zuin, Lucia; Hu, Yongfeng; Sun, Yang-Kook; Scrosati, Bruno; Curtiss, Larry A.; Amine, Khalil

    2013-05-13

    Nonaqueous lithium–oxygen batteries have a much superior theoretical gravimetric energy density compared to conventional lithium-ion batteries, and thus could render long-range electric vehicles a reality. A molecular-level understanding of the reversible formation of lithium peroxide in these batteries, the properties of major/minor discharge products, and the stability of the nonaqueous electrolytes is required to achieve successful lithium–oxygen batteries. We demonstrate that the major discharge product formed in the lithium–oxygen cell, lithium peroxide, exhibits a magnetic moment. These results are based on dc-magnetization measurements and a lithium– oxygen cell containing an ether-based electrolyte. The results are unexpected because bulk lithium peroxide has a significant band gap. Density functional calculations predict that superoxide- type surface oxygen groups with unpaired electrons exist on stoichiometric lithium peroxide crystalline surfaces and on nanoparticle surfaces; these computational results are consistent with the magnetic measurement of the discharged lithium peroxide product as well as EPR measurements on commercial lithium peroxide. The presence of superoxide-type surface oxygen groups with spin can play a role in the reversible formation and decomposition of lithium peroxide as well as the reversible formation and decomposition of electrolyte molecules.

  10. Magnetism in lithium-oxygen discharge product.

    PubMed

    Lu, Jun; Jung, Hun-Ji; Lau, Kah Chun; Zhang, Zhengcheng; Schlueter, John A; Du, Peng; Assary, Rajeev S; Greeley, Jeffrey; Ferguson, Glen A; Wang, Hsien-Hau; Hassoun, Jusef; Iddir, Hakim; Zhou, Jigang; Zuin, Lucia; Hu, Yongfeng; Sun, Yang-Kook; Scrosati, Bruno; Curtiss, Larry A; Amine, Kahlil

    2013-07-01

    Nonaqueous lithium-oxygen batteries have a much superior theoretical gravimetric energy density compared to conventional lithium-ion batteries, and thus could render long-range electric vehicles a reality. A molecular-level understanding of the reversible formation of lithium peroxide in these batteries, the properties of major/minor discharge products, and the stability of the nonaqueous electrolytes is required to achieve successful lithium-oxygen batteries. We demonstrate that the major discharge product formed in the lithium-oxygen cell, lithium peroxide, exhibits a magnetic moment. These results are based on dc-magnetization measurements and a lithium-oxygen cell containing an ether-based electrolyte. The results are unexpected because bulk lithium peroxide has a significant band gap. Density functional calculations predict that superoxide-type surface oxygen groups with unpaired electrons exist on stoichiometric lithium peroxide crystalline surfaces and on nanoparticle surfaces; these computational results are consistent with the magnetic measurement of the discharged lithium peroxide product as well as EPR measurements on commercial lithium peroxide. The presence of superoxide-type surface oxygen groups with spin can play a role in the reversible formation and decomposition of lithium peroxide as well as the reversible formation and decomposition of electrolyte molecules.

  11. Vibrationally Resolved Electron Attachment to Oxygen Clusters

    NASA Astrophysics Data System (ADS)

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

    1996-10-01

    Highly monochromatized electrons (with 30 meV FWHM) are used in a crossed beam experiment to investigate electron attachment to oxygen clusters \\(O2\\)n at electron energies from approximately 0 to 2 eV. At energies close to zero, the attachment cross section for the reaction \\(O2\\)n+e-->O-2 rises strongly with decreasing electron energy compatible with s-wave electron capture to \\(O2\\)n. Peaks in the attachment cross section present at higher energies can be ascribed to vibrational levels of the oxygen anion. The vibrational spacings observed can be quantitatively accounted for by model calculations.

  12. Influence of ortho-substitution homolog group on polychlorobiphenyl bioaccumulation factors and fugacity ratios in plankton and zebra mussels (Dreissena polymorpha)

    SciTech Connect

    Willman, E.J.; Manchester-Neesvig, J.B.; Agrell, C.; Armstrong, D.E.

    1999-07-01

    The accumulation of a set of non- and mono-ortho (coplanar) PCB congeners in aquatic ecosystems is of interest due to their dioxin-like toxicities. Chemical properties (octanol-water partition coefficients) suggest that the coplanar congeners may accumulate in organisms to a greater extent than homologs with greater ortho substitution. The authors analyzed a set of 65 PCB congeners with zero to four ortho-chlorines from seven homolog groups in water, suspended particulate matter, and zebra mussels from Green Bay, Wisconsin, USA, on four dates throughout the ice-free season. The suspended particulate matter was separated by size and characterized as phytoplankton or zooplankton using diagnostic carotenoid pigments and light microscopy. Median bioconcentration factors (BCFs) for accumulation from water by phytoplankton and bioaccumulation factors (BAFs) for accumulation from water plus food by zooplankton and zebra mussels ranged from 1 x 10{sup 4} to 1 x 10{sup 6} and were generally the greatest for the tetra- to heptachlorobiphenyls. The average coplanar congener BCFs and BAFs for accumulation from water by phytoplankton, zooplankton, and zebra mussels for the tri-, tetra-, and pentachlorobiphenyls were 54% larger than corresponding values for their homologs. Biomagnification factors (BMFs) of the tetra-, penta-, and hexachlorobiphenyls between zooplankton and zebra mussels and their food source, phytoplankton, typically ranged between 1 and 10, but the average coplanar congener BMFs were 25% less than values for their corresponding homologs. The tendency for coplanar congeners to accumulate to a lesser extent between trophic levels was not as large as their tendency to accumulate from water to a greater extent. Based on accumulation factors, the authors conclude that the dioxin-like tetra- and pentachlorobiphenyls generally accumulate in the phytoplankton, zooplankton, and zebra mussels of the Green Bay ecosystem to a greater extent than other congeners. Fugacity

  13. Oxygen and Biological Evolution.

    ERIC Educational Resources Information Center

    Baugh, Mark A.

    1990-01-01

    Discussed is the evolution of aerobic organisms from anaerobic organisms and the accompanying biochemistry that developed to motivate and enable this evolution. Uses of oxygen by aerobic organisms are described. (CW)

  14. Hyperbaric Oxygen Therapy

    MedlinePlus

    ... causes tissue death Nonhealing wounds, such as a diabetic foot ulcer Radiation injury Skin graft or skin flap ... hyperbaric oxygenation therapy in the management of chronic diabetic foot ulcers. Mayo Clinic Proceedings. 2013;88:166. Indications ...

  15. 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.

  16. Medical Oxygen Safety

    MedlinePlus

    ... injuries and deaths. from a heat source, open flames or electrical devices. KKK Body oil, hand lotion ... the oxygen. Post No Smoking and No Open Flames signs in and outside the home to remind ...

  17. High Selectivity Oxygen Delignification

    SciTech Connect

    Lucian A. Lucia

    2005-11-15

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

  18. 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

  19. [Oxygen Leukocyte Larceny].

    PubMed

    Pinto da Costa, Miguel; Pimenta Coelho, Henrique

    2016-05-01

    The authors present a case of a 60-year-old male patient, previously diagnosed with B-cell chronic lymphocytic leukemia, who was admitted to the Emergency Room with dyspnea. The initial evaluation revealed severe anemia (Hgb = 5.0 g/dL) with hyperleukocytosis (800.000/µL), nearly all of the cells being mature lymphocytes, a normal chest X-ray and a low arterial oxygen saturation (89%; pulse oximetry). After red blood cell transfusion, Hgb values rose (9.0 g/dL) and there was a complete reversion of the dyspnea. Yet, subsequent arterial blood gas analysis, without the administration of supplemental oxygen, systematically revealed very low oxygen saturation values (~ 46%), which was inconsistent with the patientâs clinical state and his pulse oximetry values (~ 87%), and these values were not corrected by the administration of oxygen via non-rebreather mask. The investigation performed allowed to establish the diagnosis of oxygen leukocyte larceny, a phenomenon which conceals the true oxygen saturation due to peripheral consumption by leukocytes.

  20. Electron-beam sustained discharge in oxygen gas mixtures: singlet delta oxygen production for oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Frolov, Mikhail P.; Hager, Gordon D.; Ionin, Andrei A.; Klimachev, Yurii M.; Kochetov, Igor V.; Kotkov, Andrei A.; McIver, John K.; Napartovich, Anatolii P.; Podmar'kov, Yurii P.; Seleznev, Leonid V.; Sinitsyn, Dmitrii V.; Vagin, Nikolai P.; Yuryshev, Nikolay N.

    2004-09-01

    Electric properties and spectroscopy of an e-beam sustained discharge (EBSD) in oxygen and oxygen gas mixtures at gas pressure up to 100 Torr were experimentally studied. The pulsed discharge in pure oxygen and its mixtures with noble gases was shown to be very unstable and characterized by low input energy. When adding small amount of carbon monoxide or hydrogen, the electric stability of the discharge increases, specific input energy (SIE) per molecular component being more than order of magnitude higher and coming up to 6.5 kJ/(l atm) for gas mixture O2:Ar:CO = 1:1:0.1. The results of experiments on spectroscopy of the singlet delta oxygen O2(a1Δg)(SDO) and O2(b1Σg+) states in the EBSD are presented. The calibration of the optical scheme for measuring the SDO absolute concentration and yield using the detection of luminescence of the SDO going from a chemical SDO generator was done. The preliminary measurement of the SDO yield demonstrated that it was ~3% for the SIE of ~1 kJ/(l atm), which is close to the results of theoretical calculations for such a SIE. Theoretical calculations demonstrated that for the SIE of 6.5 kJ/(l atm) the SDO yield may reach ~20% exceeding its threshold value needed for oxygen-iodine laser operation at room temperature, although a part of the energy loaded into the EBSD goes into the vibrational energy of the molecular admixture, (which was experimentally demonstrated by launching a CO laser operating on an oxygen-rich mixture O2:Ar:CO = 1:1:0.1 and measuring its small-signal gain).

  1. Atmospheric odd oxygen production due to the photodissociation of ordinary and isotopic molecular oxygen

    NASA Technical Reports Server (NTRS)

    Omidvar, K.; Frederick, J. E.

    1987-01-01

    Line-by-line calculations are performed to determine the contributions of the Schumann-Runge bands of ordinary and isotopic oxygen to the photodissociation of these molecules at different altitudes. The contributions to the dissociation rates of the satellite lines and of the first and higher vibrational states of the initial molecular states are found to be insignificant. At 70 km, (O-16)(O-18) is found to produce 10 times as much odd oxygen as would be produced if the isotope did not have selective absorption, and 6 percent of the odd oxygen produced is due to this isotope. It is noted that the excess odd oxygen produced is not enough to explain the excess quantity of ozone observed in the atmosphere, which cannot be accounted for in photochemical models. Comparison with previous results is made.

  2. Personal Finance Calculations.

    ERIC Educational Resources Information Center

    Argo, Mark

    1982-01-01

    Contains explanations and examples of mathematical calculations for a secondary level course on personal finance. How to calculate total monetary cost of an item, monthly payments, different types of interest, annual percentage rates, and unit pricing is explained. (RM)

  3. Lunar oxygen production by pyrolysis of regolith

    NASA Technical Reports Server (NTRS)

    Senior, Constance L.

    1991-01-01

    Oxygen represents one of the most desirable products of lunar mining and manufacturing. Among the many processes which have been proposed for oxygen production, pyrolysis stands out as one which is uncomplicated and easy to bootstrap. Pyrolysis or vapor-phase reduction involves heating regolith to temperatures sufficient to allow partial decomposition and vaporization. Some metal oxides give up oxygen upon heating, either in the gas phase to form reduced gaseous species or in the condensed phase to form a metallic phase. Based on preliminary experiments and equilibrium calculations, the temperatures needed for pyrolysis are expected to be in the range of 2000 to 2200 K, giving total gas pressures of 0.001 to 0.1 torr. Bulk regolith can be used as a feedstock without beneficiation with concentrated solar radiation supplying most of energy needed. Further, selective condensation of metal-containing species from the gas phase may yield metallic iron and silicon as byproducts.

  4. Calculators, Computers, and Classrooms.

    ERIC Educational Resources Information Center

    Higgins, Jon L.; Kirschner, Vicky

    Suggestions for using four-function calculators, programmable calculators, and microcomputers are considered in this collection of 36 articles. The first section contains articles considering general implications for mathematics curricula implied by the freedom calculators offer students from routine computation, enabling them to focus on results…

  5. Venous oxygen saturation.

    PubMed

    Hartog, Christiane; Bloos, Frank

    2014-12-01

    Early detection and rapid treatment of tissue hypoxia are important goals. Venous oxygen saturation is an indirect index of global oxygen supply-to-demand ratio. Central venous oxygen saturation (ScvO2) measurement has become a surrogate for mixed venous oxygen saturation (SvO2). ScvO2 is measured by a catheter placed in the superior vena cava. After results from a single-center study suggested that maintaining ScvO2 values >70% might improve survival rates in septic patients, international practice guidelines included this target in a bundle strategy to treat early sepsis. However, a recent multicenter study with >1500 patients found that the use of central hemodynamic and ScvO2 monitoring did not improve long-term survival when compared to the clinical assessment of the adequacy of circulation. It seems that if sepsis is recognized early, a rapid initiation of antibiotics and adequate fluid resuscitation are more important than measuring venous oxygen saturation.

  6. Optical oxygen concentration monitor

    DOEpatents

    Kebabian, P.

    1997-07-22

    A system for measuring and monitoring the concentration of oxygen uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to one of oxygen`s A-band absorption lines. In a preferred embodiment, the argon line is split into sets of components of shorter and longer wavelengths by a magnetic field of approximately 2,000 Gauss that is parallel to the light propagation from the lamp. The longer wavelength components are centered on an absorption line of oxygen and thus readily absorbed, and the shorter wavelength components are moved away from that line and minimally absorbed. A polarization modulator alternately selects the set of the longer wavelength, or upshifted, components or the set of the shorter wavelength, or downshifted, components and passes the selected set to an environment of interest. After transmission over a path through that environment, the transmitted optical flux of the argon line varies as a result of the differential absorption. The system then determines the concentration of oxygen in the environment based on the changes in the transmitted optical flux between the two sets of components. In alternative embodiments modulation is achieved by selectively reversing the polarity of the magnetic field or by selectively supplying the magnetic field to either the emitting plasma of the lamp or the environment of interest. 4 figs.

  7. Atomic oxygen stimulated outgassing

    NASA Technical Reports Server (NTRS)

    Linton, Roger C.; Reynolds, John M.

    1991-01-01

    The passive Long Duration Exposure Facility (LDEF) Experiment A0034, Atomic Oxygen Simulated Outgassing, consisted of two identical one-sixth tray modules, exposing selected thermal control coatings to atomic oxygen and the combined space environment on the leading edge and, for reference, to the relative wake environment on the trailing edge. Optical mirrors were included adjacent to the thermal coatings for deposition of outgassing products. Ultraviolet grade windows and metal covers were provided for additional assessment of the effects of the various environmental factors. Preliminary results indicate that orbital atomic oxygen is both a degrading and a optically restorative factor in the thermo-optical properties of selected thermal coatings. There is evidence of more severe optical degradation on collector mirrors adjacent to coatings that were exposed to the RAM-impinging atomic oxygen. This evidence of atomic oxygen stimulated outgassing is discussed in relation to alternative factors that could affect degradation. The general effects of the space environment on the experiment hardware as well as the specimens are discussed.

  8. How Do Calculators Calculate Trigonometric Functions?

    ERIC Educational Resources Information Center

    Underwood, Jeremy M.; Edwards, Bruce H.

    How does your calculator quickly produce values of trigonometric functions? You might be surprised to learn that it does not use series or polynomial approximations, but rather the so-called CORDIC method. This paper will focus on the geometry of the CORDIC method, as originally developed by Volder in 1959. This algorithm is a wonderful…

  9. Wildlife monitoring, modeling, and fugacity

    SciTech Connect

    Clark, T.; Clark, K.; Paterson, S.; Mackay, D.; Norstrom, R.J. )

    1988-02-01

    Observations of wildlife populations and their state of health have played a key role in identifying situations in which chemical contaminants have reached unacceptable concentrations in the environment. The reproductive failure of several species - including the peregrine falcon (Falco peregrinus), the double crested cormorant (Phalocrocorax auritus), the brown pelican (Pelicanus occidentalis), and the osprey (Pandion haliaetus) - has been attributed to organochlorine contamination. As the mine canary can warn of the presence of a poisonous gas in a coal mine, wildlife populations can act as sentinels for excessive chemical contamination. This blunt and often tragic exploitation of wildlife as a sentinel is, to be sure, an extreme example of the more subtle and far-reaching issue of the extent to which wildlife tissues can be used to indicate general levels of environmental contamination and provide guidance to the scientific and regulatory communities about the state of the environment.

  10. Monolithic solid electrolyte oxygen pump

    DOEpatents

    Fee, Darrell C.; Poeppel, Roger B.; Easler, Timothy E.; Dees, Dennis W.

    1989-01-01

    A multi-layer oxygen pump having a one-piece, monolithic ceramic structure affords high oxygen production per unit weight and volume and is thus particularly adapted for use as a portable oxygen supply. The oxygen pump is comprised of a large number of small cells on the order of 1-2 millimeters in diameter which form the walls of the pump and which are comprised of thin, i.e., 25-50 micrometers, ceramic layers of cell components. The cell components include an air electrode, an oxygen electrode, an electrolyte and interconnection materials. The cell walls form the passages for input air and for exhausting the oxygen which is transferred from a relatively dilute gaseous mixture to a higher concentration by applying a DC voltage across the electrodes so as to ionize the oxygen at the air electrode, whereupon the ionized oxygen travels through the electrolyte and is converted to oxygen gas at the oxygen electrode.

  11. 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

  12. Neurological oxygen toxicity.

    PubMed

    Farmery, Scott; Sykes, Oliver

    2012-10-01

    SCUBA diving has several risks associated with it from breathing air under pressure--nitrogen narcosis, barotrauma and decompression sickness (the bends). Trimix SCUBA diving involves regulating mixtures of nitrogen, oxygen and helium in an attempt to overcome the risks of narcosis and decompression sickness during deep dives, but introduces other potential hazards such as hypoxia and oxygen toxicity convulsions. This study reports on a seizure during the ascent phase, its potential causes and management and discusses the hazards posed to the diver and his rescuer by an emergency ascent to the surface.

  13. 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

    2004-05-01

    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, in situ neutron diffraction was used to characterize the chemical and structural properties of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} (here after as L2SF55T) specimen, which was subject to measurements of neutron diffraction from room temperature to 900 C in N{sub 2}. Space group of R3c was found to result in a better refinement and is used in this study. The difference for crystal structure, lattice parameters and local crystal chemistry for LSFT nearly unchanged when gas environment switched from air to N{sub 2}. Stable crack growth studies on Dense OTM bars provided by Praxair were done at room temperature in air. A bridge-compression fixture was fabricated to achieve stable pre-cracks from Vickers indents. Post fracture evaluation indicated stable crack growth from the indent and a regime of fast fracture. 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. The thermal and chemical expansion of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} were studied at 800 {le} T {le} 1000 C and at {approx} 1 x 10{sup -15} {le} pO{sub 2} {le} 0.21 atm. The thermal expansion coefficient of the sample was calculated from the dilatometric analysis in the temperature range between room temperature and 1200 C in air. 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

  14. Biological Oxygen Productivity Over The Last Glacial Termination From Triple Oxygen Isotope Measurements

    NASA Astrophysics Data System (ADS)

    Blunier, T.; Bender, M. L.; Hendricks, M. B.

    The atmospheric oxygen isotope signature of O2 is linked to the oxygen signature of seawater through photosynthesis and respiration. Fractionation during these pro- cesses is mass dependent affecting 17O about half as much as 18O. A mass indepen- dent fractionation process takes place during isotope exchange between O2 and CO2 in the stratosphere (Thiemens, 1999; Luz et al., 1999). The magnitude of the mass- independent anomaly in the triple isotope composition of O2 depends on relative rates of biological O2 cycling and photochemical reactions in the stratosphere. Variations of this anomaly thus allows us to estimate changes of mass dependent O2 production by photosynthesis versus mass independent O2-CO2 exchange in the stratosphere. We reconstruct total oxygen productivity for the past from 17O and 18O measure- ments of O2 trapped in ice cores. With a box model we estimate that the total biogenic productivity was only 76-83 % of today for the glacial and was probably still lower than today during the glacial-interglacial transition and the early Holocene. In principle we can calculate the oxygen flux from the ocean biosphere if we know the oxygen flux from the land biosphere. Calculated ocean production is very sensitive to the estimate of land biosphere production. The latter term remains uncertain, however, and we can presently only constrain glacial ocean production to 88 to 140 % of the present value.

  15. Oxygen vacancy induced surface stabilization: (110) terminated magnetite

    NASA Astrophysics Data System (ADS)

    Walls, B.; Lübben, O.; Palotás, K.; Fleischer, K.; Walshe, K.; Shvets, I. V.

    2016-10-01

    Scanning tunneling microscopy (STM) measurements of the (110) surface of magnetite showed the coexistence of two reconstructions: the known (1 ×3 ) row reconstruction and a surprising atomic structure of high complexity which occupies a small fraction of the surface. Oxygen vacancies on the Fe3O4 (110) B-terminated surface have previously been determined to be the most energetically favorable surface termination of those considered [Li et al., Surf. Sci. 601, 876 (2007), 10.1016/j.susc.2006.10.037]. However, this study only investigated oxygen vacancies which were threefold coordinated. Here, first principles calculations indicate that twofold coordinated oxygen represents the most energetically stable oxygen vacancy on the B-terminated (110) surface of magnetite. STM simulations reveal that the structure that occupies a small fraction of the surface corresponds to this energetically favorable B-terminated Fe3O4 (110) surface. The oxygen vacancies form an ordered array: Along the [1 ¯10 ] direction, every second twofold coordinated oxygen atom is vacant, and vacancies are separated by 6 Å. In adjacent twofold coordinated oxygen rows, the vacancies are shifted in the [1 ¯10 ] direction by 3 Å. Density functional theory calculations of the spin density distributions indicate that surface and subsurface octahedrally coordinated iron atoms are charge ordered. The charge ordering and existence of oxygen vacancies act to reduce the surface charge. However, other polarity compensation mechanisms may be at play to stabilize the surface.

  16. The Oxygen Cycle.

    ERIC Educational Resources Information Center

    Swant, Gary D.

    Produced for primary grades, this booklet provides study of the oxygen-carbon dioxide cycle in nature. Line drawings, a minimum amount of narrative, and a glossary of terms make up its content. The booklet is designed to be used as reading material, a coloring book, or for dramatic arts with students acting out parts of the cycle. This work was…

  17. 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.

  18. The Oxygen Flask Method

    ERIC Educational Resources Information Center

    Boulton, L. H.

    1973-01-01

    Discusses application of Schoniger's method of quantitative organic elemental analysis in teaching of qualitative analysis of the halogens, nitrogen, sulphur, and phosphorus. Indicates that the oxygen flask method is safe and suitable for both high school and college courses because of simple apparatus requirements. (CC)

  19. Oxygenated Derivatives of Hydrocarbons

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For the book entitled “Insect Hydrocarbons: Biology, Biochemistry and Chemical Ecology”, this chapter presents a comprehensive review of the occurrence, structure and function of oxygenated derivatives of hydrocarbons. The book chapter focuses on the occurrence, structural identification and functi...

  20. Optical oxygen concentration monitor

    DOEpatents

    Kebabian, Paul

    1997-01-01

    A system for measuring and monitoring the concentration of oxygen uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to one of oxygen's A-band absorption lines. In a preferred embodiment, the argon line is split into sets of components of shorter and longer wavelengths by a magnetic field of approximately 2000 Gauss that is parallel to the light propagation from the lamp. The longer wavelength components are centered on an absorption line of oxygen and thus readily absorbed, and the shorter wavelength components are moved away from that line and minimally absorbed. A polarization modulator alternately selects the set of the longer wavelength, or upshifted, components or the set of the shorter wavelength, or downshifted, components and passes the selected set to an environment of interest. After transmission over a path through that environment, the transmitted optical flux of the argon line varies as a result of the differential absorption. The system then determines the concentration of oxygen in the environment based on the changes in the transmitted optical flux between the two sets of components. In alternative embodiments modulation is achieved by selectively reversing the polarity of the magnetic field or by selectively supplying the magnetic field to either the emitting plasma of the lamp or the environment of interest.

  1. 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.

  2. Hybrid Oxygen System

    DTIC Science & Technology

    1992-10-01

    otherwise in any manner construed, as licensing the holder or any other person or corporation ; or as conveying any rights or permission to manufacture, use...12 Modest Activity 2 12 24 Comnat ane G’s Average 5 32 64 Peak Activity (NATO) 10 50 Instantaneous Peak Flow N/A 150-20W_ Published oxygen flow rates

  3. Multiphase flow calculation software

    DOEpatents

    Fincke, James R.

    2003-04-15

    Multiphase flow calculation software and computer-readable media carrying computer executable instructions for calculating liquid and gas phase mass flow rates of high void fraction multiphase flows. The multiphase flow calculation software employs various given, or experimentally determined, parameters in conjunction with a plurality of pressure differentials of a multiphase flow, preferably supplied by a differential pressure flowmeter or the like, to determine liquid and gas phase mass flow rates of the high void fraction multiphase flows. Embodiments of the multiphase flow calculation software are suitable for use in a variety of applications, including real-time management and control of an object system.

  4. Evapotranspiration Calculator Desktop Tool

    EPA Pesticide Factsheets

    The Evapotranspiration Calculator estimates evapotranspiration time series data for hydrological and water quality models for the Hydrologic Simulation Program - Fortran (HSPF) and the Stormwater Management Model (SWMM).

  5. Calculating Toxic Corridors.

    DTIC Science & Technology

    1980-11-01

    nomograms, and a programmable calculator . Appendices present worksheets, example problems, procedures for determining meteorological inputs, a procedure for determining evaporative source strength, and other items.

  6. 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

  7. Reaction of oxygen with allene

    SciTech Connect

    Huang, Sheng-yu

    1988-07-01

    Elastic scattering studies carried out independently of the work related to the title forms the first section of the dissertation. The low-energy elastic scattering of He with Ar, Kr, Xe has been studied by molecular beam techniques. Two potential forms, exponential-spline-Morse-Morse-spline-van de Waals (ESMMSV) and Simon-Parr-Finlan-Dunham (SPFD), have been used to fit the measured differential cross section. Elastic scattering theory and experimental details are introduced. The reactive scattering of O(/sup 3/P) with allene has been studied using crossed molecular beams. Differing from the well known central-carbon-attack (CCA) mechanism in which the final products, carbon monoxide and ethylene, are obtained via a ring intermediate, a new mechanism, terminal-carbon-attack (TCA), has been observed. The production of O(/sup 3/P) atoms by radio frequency discharge is also introduced. To assist understanding of the experiments a multi-configuration self-consistent field (MCSCF) study of the reaction of O(/sup 3/P) with allene has been carried out. The key feature of the oxygen-allene potential energy surface for both CCA and TCA channels has been calculated with single-zeta (SZ), double-zeta (DZ), and double-zeta plus polarization (DZP) basis sets. Finally, an algorithm for optimizing the trial wavefunction in quantum Monte Carlo calculations has been developed. With the application of group theory, a symmetry-constrained optimization process can yield an improved trial wavefunction for the calculation of excited electronic state energies as well as the ground-state energy. Several applications are discussed. 145 refs.

  8. [Understanding dosage calculations].

    PubMed

    Benlahouès, Daniel

    2016-01-01

    The calculation of dosages in paediatrics is the concern of the whole medical and paramedical team. This activity must generate a minimum of risks in order to prevent care-related adverse events. In this context, the calculation of dosages is a practice which must be understood by everyone.

  9. Electron beam dose calculations.

    PubMed

    Hogstrom, K R; Mills, M D; Almond, P R

    1981-05-01

    Electron beam dose distributions in the presence of inhomogeneous tissue are calculated by an algorithm that sums the dose distribution of individual pencil beams. The off-axis dependence of the pencil beam dose distribution is described by the Fermi-Eyges theory of thick-target multiple Coulomb scattering. Measured square-field depth-dose data serve as input for the calculations. Air gap corrections are incorporated and use data from'in-air' measurements in the penumbra of the beam. The effective depth, used to evaluate depth-dose, and the sigma of the off-axis Gaussian spread against depth are calculated by recursion relations from a CT data matrix for the material underlying individual pencil beams. The correlation of CT number with relative linear stopping power and relative linear scattering power for various tissues is shown. The results of calculations are verified by comparison with measurements in a 17 MeV electron beam from the Therac 20 linear accelerator. Calculated isodose lines agree nominally to within 2 mm of measurements in a water phantom. Similar agreement is observed in cork slabs simulating lung. Calculations beneath a bone substitute illustrate a weakness in the calculation. Finally a case of carcinoma in the maxillary antrum is studied. The theory suggests an alternative method for the calculation of depth-dose of rectangular fields.

  10. Sample size calculations.

    PubMed

    Noordzij, Marlies; Dekker, Friedo W; Zoccali, Carmine; Jager, Kitty J

    2011-01-01

    The sample size is the number of patients or other experimental units that need to be included in a study to answer the research question. Pre-study calculation of the sample size is important; if a sample size is too small, one will not be able to detect an effect, while a sample that is too large may be a waste of time and money. Methods to calculate the sample size are explained in statistical textbooks, but because there are many different formulas available, it can be difficult for investigators to decide which method to use. Moreover, these calculations are prone to errors, because small changes in the selected parameters can lead to large differences in the sample size. This paper explains the basic principles of sample size calculations and demonstrates how to perform such a calculation for a simple study design.

  11. Effect of energetic oxygen atoms on neutral density models.

    NASA Technical Reports Server (NTRS)

    Rohrbaugh, R. P.; Nisbet, J. S.

    1973-01-01

    The dissociative recombination of O2(+) and NO(+) in the F region results in the production of atomic oxygen and atomic nitrogen with substantially greater kinetic energy than the ambient atoms. In the exosphere these energetic atoms have long free paths. They can ascend to altitudes of several thousand kilometers and can travel horizontally to distances of the order of the earth's radius. The distribution of energetic oxygen atoms is derived by means of models of the ion and neutral densities for quiet and disturbed solar conditions. A distribution technique is used to study the motion of the atoms in the collision-dominated region. Ballistic trajectories are calculated in the spherical gravitational field of the earth. The present calculations show that the number densities of energetic oxygen atoms predominate over the ambient atomic oxygen densities above 1000 km under quiet solar conditions and above 1600 km under disturbed solar conditions.

  12. Safety of Propofol for Oxygenator Exchange in Extracorporeal Membrane Oxygenation.

    PubMed

    Hohlfelder, Benjamin; Szumita, Paul M; Lagambina, Susan; Weinhouse, Gerald; Degrado, Jeremy R

    The purpose of this analysis is to describe the safety of propofol administration in adult extracorporeal membrane oxygenation (ECMO) patients. We performed a prospective cohort analysis of patients using ECMO at Brigham and Women's Hospital between February 2013 and October 2015. Patients were included if they used ECMO for at least 48 hours. The major end-point of the analysis was the median oxygenator lifespan. Oxygenator exchanges were analyzed by the number of patients requiring an oxygenator exchange and the number of oxygenator exchanges per ECMO day. A priori analysis was performed by comparing the outcomes between patients who did and did not receive propofol during their ECMO course. During the study, 43 patients were included in the analysis. Sixteen patients used propofol during their ECMO course. There were 12 oxygenator exchanges during therapy. Oxygenator exchange occurred on 1.8% of ECMO days. The median oxygenator lifespan was 7 days. Patients who used propofol had a significantly longer oxygenator lifespan (p = 0.02). Among patients who received propofol, patients who required oxygenator exchange used a significantly lower median daily dose of propofol (p < 0.001). The use of propofol appears safe in ECMO with regards to oxygenator viability. Contrary to expected, oxygenator lifespan was significantly longer among patients who received propofol.

  13. The jumbo squid, Dosidicus gigas (Ommastrephidae), living in oxygen minimum zones I: Oxygen consumption rates and critical oxygen partial pressures

    NASA Astrophysics Data System (ADS)

    Trueblood, Lloyd A.; Seibel, Brad A.

    2013-10-01

    Dosidicus gigas is a large, metabolically active, epipelagic squid known to undertake diel vertical migrations across a large temperature and oxygen gradient in the Eastern Pacific. Hypoxia is known to cause metabolic suppression in D. gigas. However, the precise oxygen level at which metabolic suppression sets in is unknown. Here we describe a novel ship-board swim tunnel respirometer that was used to measure metabolic rates and critical oxygen partial pressures (Pcrit) for adult squids (2-7kg). Metabolic rate measurements were validated by comparison to the activity of the Krebs cycle enzyme, citrate synthase, in mantle muscle tissue (2-17kg). We recorded a mean routine metabolic rate of 5.91μmolg-1h-1 at 10°C and 12.62μmolg-1h-1 at 20°C. A temperature coefficient, Q10, of 2.1 was calculated. D. gigas had Pcrits of 1.6 and 3.8kPa at 10 and 20°C, respectively. Oxygen consumption rate (MO2) varied with body mass (M) according to MO2=11.57M-0.12±0.03 at 10°C. Citrate synthase activity varied with body mass according to Y=9.32M-0.19±0.02.

  14. 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.

  15. High pressure oxygen furnace

    DOEpatents

    Morris, Donald E.

    1992-01-01

    A high temperature high pressure oxygen furnace having a hybrid partially externally heated construction is disclosed. A metallic bar fabricated from an alloy having a composition of at least 45% nickel, 15% chrome, and 10% tungsten is utilized (the preferred alloy including 55% nickel, 22% chrome, 14% tungsten, 2% molybdenum, 3% iron (maximum) and 5% cobalt (maximum). The disclosed alloy is fabricated into 11/4 inch bar stock and has a length of about 17 inches. This bar stock is gun drilled for over 16 inches of its length with 0.400 inch aperture to define a closed high temperature, high pressure oxygen chamber. The opposite and closed end of the bar is provided with a small support aperture into which both a support and a thermocouple can be inserted. The closed end of the gun drilled bar is inserted into an oven, preferably heated by standard nickel chrome electrical elements and having a heavily insulated exterior.

  16. High pressure oxygen furnace

    DOEpatents

    Morris, D.E.

    1992-07-14

    A high temperature high pressure oxygen furnace having a hybrid partially externally heated construction is disclosed. A metallic bar fabricated from an alloy having a composition of at least 45% nickel, 15% chrome, and 10% tungsten is utilized, the preferred alloy including 55% nickel, 22% chrome, 14% tungsten, 2% molybdenum, 3% iron (maximum) and 5% cobalt (maximum). The disclosed alloy is fabricated into 11/4 inch bar stock and has a length of about 17 inches. This bar stock is gun drilled for over 16 inches of its length with 0.400 inch aperture to define a closed high temperature, high pressure oxygen chamber. The opposite and closed end of the bar is provided with a small support aperture into which both a support and a thermocouple can be inserted. The closed end of the gun drilled bar is inserted into an oven, preferably heated by standard nickel chrome electrical elements and having a heavily insulated exterior. 5 figs.

  17. Oxygenic photosynthesis without galactolipids

    PubMed Central

    Awai, Koichiro; Ohta, Hiroyuki; Sato, Naoki

    2014-01-01

    The thylakoid membranes of oxygenic photosynthetic organisms are dominated by the galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG). In cyanobacteria, MGDG is synthesized via monoglucosyldiacylglycerol (GlcDG). However, the putative epimerase involved in the conversion of GlcDG to MGDG has not been identified. Here we report the identification of the gene for the glucolipid epimerase (mgdE) by comparative genomic analysis. Knockout mutants of mgdE in Synechocystis sp. PCC 6803 lacked both MGDG and DGDG and accumulated GlcDG. The mutants did possess thylakoid membranes and showed normal maximal photosynthetic activity, albeit with reduced utilization of light energy. These results cast doubt on the long-standing belief that oxygenic photosynthesis is absolutely dependent on galactolipids. PMID:25197079

  18. 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.

  19. Simulation of the kinetics of oxygen complexes in crystalline silicon

    NASA Astrophysics Data System (ADS)

    Joo Lee, Young; von Boehm, J.; Nieminen, R. M.

    2002-10-01

    The formation kinetics of thermal double donors (TDD's) is studied by a general kinetic model with parameters based on accurate ab initio total-energy calculations. The kinetic model includes all relevant association, dissociation, and restructuring processes. The simulated kinetics agrees qualitatively and in most cases quantitatively with the experimentally found consecutive kinetics of TDD's. It also supports our earlier assignments of the ring-type oxygen chains to TDD's [Pesola et al., Phys. Rev. Lett. 84, 5343 (2000)]. We demonstrate with the kinetic model that the most common assumption that only the O2 dimer acts as a fast diffusing species would lead to an unrealistic steady increase of the concentration of O3. The neglect of restructuring processes leads to an anomalous increase of oxygen dimers and negligible concentrations of TDD's. The capture of interstitial oxygens by diffusing oxygen chains and the escaping of interstitial oxygens from the chains fully dominate the formation kinetics.

  20. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-08-01

    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 the previous research, the reference point of oxygen occupancy was determined and verified. In the current research, the oxygen occupancy was investigated at 1200 C as a function of oxygen activity and compared with that at 1000 C. The cause of bumps at about 200 C was also investigated by using different heating and cooling rates during TGA. The fracture toughness of LSFT and dual phase membranes at room temperature is an important mechanical property. Vicker's indentation method was used to evaluate this toughness. Through this technique, a K{sub Ic} (Mode-I Fracture Toughness) value is attained by means of semi-empirical correlations between the indentation load and the length of the cracks emanating from the corresponding Vickers indentation impression. In the present investigation, crack propagation behavior was extensively analyzed in order to understand the strengthening mechanisms involved in the non-transforming La based ceramic composites. Cracks were generated using Vicker's indenter and used to identify and evaluate the toughening mechanisms involved. Preliminary results of an electron microscopy study of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Modeling of the isotopic transients on operating membranes (LSCrF-2828 at 900 C) and a ''frozen'' isotope profile have been analyzed in conjunction with a 1-D model to reveal the gradient in oxygen diffusivity through the membrane under conditions of high chemical gradients.

  1. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. The in situ electrical conductivity and Seebeck coefficient measurements were made on LSFT at 1000 and 1200 C over the oxygen activity range from air to 10{sup -15} atm. The electrical conductivity measurements exhibited a p to n type transition at an oxygen activity of 1 x 10{sup -10} at 1000 C and 1 x 10{sup -6} at 1200 C. Thermogravimetric studies were also carried out over the same oxygen activities and temperatures. Based on the results of these measurements, the chemical and mechanical stability range of LSFT were determined and defect structure was established. The studies on the fracture toughness of the LSFT and dual phase membranes exposed to air and N{sub 2} at 1000 C was done and the XRD and SEM analysis of the specimens were carried out to understand the structural and microstructural changes. The membranes that are exposed to high temperatures at an inert and a reactive atmosphere undergo many structural and chemical changes which affect the mechanical properties. A complete transformation of fracture behavior was observed in the N{sub 2} treated LSFT samples. Further results to investigate the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Recent results on transient kinetic data are presented. The 2-D modeling of oxygen movement has been undertaken in order to fit isotope data. The model is used to study ''frozen'' profiles in patterned or composite membranes.

  2. Fuel cell oxygen electrode

    DOEpatents

    Shanks, H.R.; Bevolo, A.J.; Danielson, G.C.; Weber, M.F.

    An oxygen electrode for a fuel cell utilizing an acid electrolyte has a substrate of an alkali metal tungsten bronze of the formula: A/sub x/WO/sub 3/ where A is an alkali metal and x is at least 0.2, which is covered with a thin layer of platinum tungsten bronze of the formula: Pt/sub y/WO/sub 3/ where y is at least 0.8.

  3. Fuel cell oxygen electrode

    DOEpatents

    Shanks, Howard R.; Bevolo, Albert J.; Danielson, Gordon C.; Weber, Michael F.

    1980-11-04

    An oxygen electrode for a fuel cell utilizing an acid electrolyte has a substrate of an alkali metal tungsten bronze of the formula: A.sub.x WO.sub.3 where A is an alkali metal and x is at least 0.2, which is covered with a thin layer of platinum tungsten bronze of the formula: Pt.sub.y WO.sub.3 where y is at least 0.8.

  4. Evolution of Oxygenic Photosynthesis

    NASA Astrophysics Data System (ADS)

    Fischer, Woodward W.; Hemp, James; Johnson, Jena E.

    2016-06-01

    The origin of oxygenic photosynthesis was the most important metabolic innovation in Earth history. It allowed life to generate energy and reducing power directly from sunlight and water, freeing it from the limited resources of geochemically derived reductants. This greatly increased global primary productivity and restructured ecosystems. The release of O2 as an end product of water oxidation led to the rise of oxygen, which dramatically altered the redox state of Earth's atmosphere and oceans and permanently changed all major biogeochemical cycles. Furthermore, the biological availability of O2 allowed for the evolution of aerobic respiration and novel biosynthetic pathways, facilitating much of the richness we associate with modern biology, including complex multicellularity. Here we critically review and synthesize information from the geological and biological records for the origin and evolution of oxygenic photosynthesis. Data from both of these archives illustrate that this metabolism first appeared in early Paleoproterozoic time and, despite its biogeochemical prominence, is a relatively late invention in the context of our planet's history.

  5. Atmospheric Oxygen Photoabsorption

    NASA Technical Reports Server (NTRS)

    Slanger, Tom G.

    1996-01-01

    The work conducted on this grant was devoted to various aspects of the photophysics and photochemistry of the oxygen molecule. Predissociation linewidths were measured for several vibrational levels in the O2(B3 Sigma(sub u)(sup -)) state, providing good agreement with other groups working on this important problem. Extensive measurements were made on the loss kinetics of vibrationally excited oxygen, where levels between v = 5 and v = 22 were investigated. Cavity ring-down spectroscopy was used to measure oscillator strengths in the oxygen Herzberg bands. The great sensitivity of this technique made it possible to extend the known absorption bands to the dissociation limit as well as providing many new absorption lines that seem to be associated with new O2 transitions. The literature concerning the Herzberg band strengths was evaluated in light of our new measurements, and we made recommendations for the appropriate Herzberg continuum cross sections to be used in stratospheric chemistry. The transition probabilities for all three Herzberg band systems were re-evaluated, and we are recommending a new set of values.

  6. Transtracheal oxygen therapy.

    PubMed

    Christopher, Kent L; Schwartz, Michael D

    2011-02-01

    Transtracheal oxygen therapy (TTO) has been used for long-term oxygen therapy for nearly 30 years. Numerous investigators have explored the potential benefits of TTO. Those results are reviewed in this article. TTO is best viewed not as a catheter but as a program for care. This article discusses patient selection for TTO. Publications evaluating complications are reviewed. In the past, a modified Seldinger technique (MST) was used for the creation of the tracheocutaneous fistula. The rather long program required for tract maturation with MST was labor-intensive and required substantial patient education and monitoring, particularly during the immature tract phase. Minor complications were not infrequent. More recently, the Lipkin method has been used to create a surgical tract under conscious sedation with topical anesthesia. The procedure is safe and well tolerated. Transtracheal oxygen is initiated the day following the procedure. Similarly, the tract matures in 7 to 10 days rather than the 6 to 8 weeks with MST. More rapid healing time and superior tract characteristics substantially reduce complications. The TTO program tailored for the Lipkin procedure is shortened, streamlined, and much less labor-intensive. Optimal outcomes with the TTO program require a committed pulmonologist, respiratory therapist, nurse, and surgeon (for the Lipkin procedure). This article discusses new directions in the use of transtracheal gas delivery, including the management of obstructive sleep apnea. Preliminary investigations regarding transtracheal augmented ventilation are presented. These include nocturnal use in severe chronic lung disease and liberation from prolonged mechanical ventilation.

  7. Dose Calculation Spreadsheet

    SciTech Connect

    Simpkins, Ali

    1997-06-10

    VENTSAR XL is an EXCEL Spreadsheet that can be used to calculate downwind doses as a result of a hypothetical atmospheric release. Both building effects and plume rise may be considered. VENTSAR XL will run using any version of Microsoft EXCEL version 4.0 or later. Macros (the programming language of EXCEL) was used to automate the calculations. The user enters a minimal amount of input and the code calculates the resulting concentrations and doses at various downwind distances as specified by the user.

  8. Ancient Oceans Had Less Oxygen

    ERIC Educational Resources Information Center

    King, Angela G.

    2004-01-01

    The amount of dissolved oxygen in the oceans in the mid-Proterozoic period has evolutionary implications since essential trace metals are redox sensitive. The findings suggest that there is global lack of oxygen in seawater.

  9. Surface acoustic wave oxygen sensor

    NASA Technical Reports Server (NTRS)

    Collman, James P.; Oglesby, Donald M.; Upchurch, Billy T.; Leighty, Bradley D.; Zhang, Xumu; Herrmann, Paul C.

    1994-01-01

    A surface acoustic wave (SAW) device that responds to oxygen pressure was developed by coating a 158 MHz quartz surface acoustic wave (SAW) device with an oxygen binding agent. Two types of coatings were used. One type was prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer containing the axial ligand. A second type was prepared with an oxygen binding porphyrin solution containing excess axial ligand without a polymer matrix. In the polymer based coatings, the copolymer served to provide the axial ligand to the oxygen binding agent and as a coating matrix on the surface of the SAW device. The oxygen sensing SAW device has been shown to bind oxygen following a Langmuir isotherm and may be used to measure the equilibrium constant of the oxygen binding compound in the coating matrix.

  10. Extreme ultraviolet spectra of highly ionized oxygen and fluorine

    NASA Technical Reports Server (NTRS)

    Pegg, D. J.; Griffin, P. M.; Haselton, H. H.; Laubert, R.; Mowat, J. R.; Thoe, R. S.; Peterson, R. S.; Sellin, I. A.

    1974-01-01

    The foil-excitation method has been used to study the extreme ultraviolet spectra of highly ionized oxygen and fluorine. Several previously unreported lines in heliumlike fluorine are reported and other newly reported lines in heliumlike oxygen have been measured to higher accuracy. Included in the measurements are certain heliumlike oxygen transitions of significance in interpretation of solar-flare spectral observations. The wavelength determinations are usually in good agreement with calculated results which includes relativistic corrections, but discrepancies arise when nonrelativistic calculations are used. A comparison of the present results and those recently obtained by theta-pinch and laser-induced plasma sources is made for both heliumlike and lithiumlike ions; a few discrepancies occur, with results in most cases in better agreement with relativistically corrected calculations. Certain unidentified lines in the spectra may be attributable to radiative transitions between quartet states of lithiumlike ions.

  11. Interval arithmetic in calculations

    NASA Astrophysics Data System (ADS)

    Bairbekova, Gaziza; Mazakov, Talgat; Djomartova, Sholpan; Nugmanova, Salima

    2016-10-01

    Interval arithmetic is the mathematical structure, which for real intervals defines operations analogous to ordinary arithmetic ones. This field of mathematics is also called interval analysis or interval calculations. The given math model is convenient for investigating various applied objects: the quantities, the approximate values of which are known; the quantities obtained during calculations, the values of which are not exact because of rounding errors; random quantities. As a whole, the idea of interval calculations is the use of intervals as basic data objects. In this paper, we considered the definition of interval mathematics, investigated its properties, proved a theorem, and showed the efficiency of the new interval arithmetic. Besides, we briefly reviewed the works devoted to interval analysis and observed basic tendencies of development of integral analysis and interval calculations.

  12. National Stormwater Calculator

    EPA Pesticide Factsheets

    EPA’s National Stormwater Calculator (SWC) is a desktop application that estimates the annual amount of rainwater and frequency of runoff from a specific site anywhere in the United States (including Puerto Rico).

  13. More Experiments and Calculations.

    ERIC Educational Resources Information Center

    Siddons, J. C.

    1984-01-01

    Describes two experiments that illustrate basic ideas but would be difficult to carry out. Also presents activities and experiments on rainbow cups, electrical charges, electrophorus calculation, pulse electrometer, a skidding car, and on the Oersted effect. (JN)

  14. PHYSICOCHEMICAL PROPERTY CALCULATIONS

    EPA Science Inventory

    Computer models have been developed to estimate a wide range of physical-chemical properties from molecular structure. The SPARC modeling system approaches calculations as site specific reactions (pKa, hydrolysis, hydration) and `whole molecule' properties (vapor pressure, boilin...

  15. Programmable calculator stress analysis

    SciTech Connect

    Van Gulick, L.A.

    1983-01-01

    This paper assesses the suitability of advanced programmable alphanumeric calculators for closed form calculation of pressure vessel stresses and offers, as their advantages, adequate computing power, portability, special programming features, and simple interactive execution procedures. Representative programs which demonstrate their capacities are presented. Problems dealing with stress and strength calculations in thick-walled pressure vessels and with the computation of stresses near head/pressure vessel junctures are treated. Assessed favorably in this paper as useful contributors to computeraided design of pressure vessels, programmable alphanumeric calculators have areas of implementation in checking finite element results, aiding in the development of an intuitive understanding of stresses and their parameter dependencies, and evaluating rapidly a variety of preliminary designs.

  16. Oxygen Transport Membranes

    SciTech Connect

    S. Bandopadhyay

    2008-08-30

    The focus of this research was to develop new membrane materials by synthesizing different compounds and determining their defect structures, crystallographic structures and electrical properties. In addition to measuring electrical conductivity, oxygen vacancy concentration was also evaluated using thermogravimetry, Neutron diffraction and Moessbauer Spectroscopy. The reducing conditions (CO{sub 2}/CO/H{sub 2} gas mixtures with steam) as encountered in a reactor environment can be expected to have significant influence on the mechanical properties of the oxides membranes. Various La based materials with and without Ti were selected as candidate membrane materials for OTM. The maximum electrical conductivity of LSF in air as a function of temperature was achieved at < 600 C and depends on the concentration of Sr (acceptor dopant). Oxygen occupancy in LSF was estimated using Neutron diffractometry and Moessbauer Spectroscopy by measuring magnetic moment changes depending on the Fe{sup 3+} and Fe{sup 4+} ratio. After extensive studies of candidate materials, lanthanum ferrites (LSF and LSFT) were selected as the favored materials for the oxygen transport membrane (OTM). LSF is a very good material for an OTM because of its high electronic and oxygen ionic conductivity if long term stability and mechanical strength are improved. LSFT not only exhibits p-type behavior in the high oxygen activity regime, but also has n-type conduction in reducing atmospheres. Higher concentrations of oxygen vacancies in the low oxygen activity regime may improve the performance of LSFT as an OTM. The hole concentration is related to the difference in the acceptor and donor concentration by the relation p = [Sr'{sub La}]-[Ti{sm_bullet}{sub Fe}]. The chemical formulation predicts that the hole concentration is, p = 0.8-0.45 or 0.35. Experimental measurements indicated that p is about {approx} 0.35. The activation energy of conduction is 0.2 eV which implies that LSCF conducts via the

  17. Oxygen consumption in subseafloor basaltic crust

    NASA Astrophysics Data System (ADS)

    Orcutt, B. N.; Wheat, C. G.; Hulme, S.; Edwards, K. J.; Bach, W.

    2012-12-01

    Oceanic crust is the largest potential habitat for life on Earth and may contain a significant fraction of Earth's total microbial biomass, yet little is known about the form and function of life in this vast subseafloor realm that covers nearly two-thirds of the Earth's surface. A deep biosphere hosted in subseafloor basalts has been suggested from several lines of evidence; yet, empirical analysis of metabolic reaction rates in basaltic crust is lacking. Here we report the first measure of oxygen consumption in young (~ 8 Ma) and cool (<25 degrees C) basaltic crust, calculated from modeling oxygen and strontium profiles in basal sediments collected during Integrated Ocean Drilling Program (IODP) Expedition 336 to 'North Pond', a sediment 'pond' on the western flank of the Mid-Atlantic Ridge (MAR), where vigorous fluid circulation within basaltic crust occurs. Dissolved oxygen concentrations increased towards the sediment-basement interface, indicating an upward diffusional supply from oxic fluids circulating within the crust. A parametric reaction-transport model suggests oxygen consumption rates on the order of 0.5-500 nmol per cubic centimeter fluid per day in young and cool basaltic crust, providing sufficient energy to support a subsurface crustal biosphere.

  18. MISSE PEACE Polymers Atomic Oxygen Erosion Results

    NASA Technical Reports Server (NTRS)

    deGroh, Kim, K.; Banks, Bruce A.; McCarthy, Catherine E.; Rucker, Rochelle N.; Roberts, Lily M.; Berger, Lauren A.

    2006-01-01

    Forty-one different polymer samples, collectively called the Polymer Erosion and Contamination Experiment (PEACE) Polymers, have been exposed to the low Earth orbit (LEO) environment on the exterior of the International Space Station (ISS) for nearly 4 years as part of Materials International Space Station Experiment 2 (MISSE 2). The objective of the PEACE Polymers experiment was to determine the atomic oxygen erosion yield of a wide variety of polymeric materials after long term exposure to the space environment. The polymers range from those commonly used for spacecraft applications, such as Teflon (DuPont) FEP, to more recently developed polymers, such as high temperature polyimide PMR (polymerization of monomer reactants). Additional polymers were included to explore erosion yield dependence upon chemical composition. The MISSE PEACE Polymers experiment was flown in MISSE Passive Experiment Carrier 2 (PEC 2), tray 1, on the exterior of the ISS Quest Airlock and was exposed to atomic oxygen along with solar and charged particle radiation. MISSE 2 was successfully retrieved during a space walk on July 30, 2005, during Discovery s STS-114 Return to Flight mission. Details on the specific polymers flown, flight sample fabrication, pre-flight and post-flight characterization techniques, and atomic oxygen fluence calculations are discussed along with a summary of the atomic oxygen erosion yield results. The MISSE 2 PEACE Polymers experiment is unique because it has the widest variety of polymers flown in LEO for a long duration and provides extremely valuable erosion yield data for spacecraft design purposes.

  19. Oxygen Sag and Stream Purification.

    ERIC Educational Resources Information Center

    Neal, Larry; Herwig, Roy

    1978-01-01

    Presents a literature review of water quality related to oxygen sag and stream purification, covering publications of 1976-77. This review includes: (1) self-purification models; (2) oxygen demand; and (3) reaeration and oxygen transfer. A list of 60 references is also presented. (HM)

  20. Quantum Chemical Calculations

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W.; Arnold, James O. (Technical Monitor)

    1997-01-01

    The current methods of quantum chemical calculations will be reviewed. The accent will be on the accuracy that can be achieved with these methods. The basis set requirements and computer resources for the various methods will be discussed. The utility of the methods will be illustrated with some examples, which include the calculation of accurate bond energies for SiF$_n$ and SiF$_n^+$ and the modeling of chemical data storage.

  1. Source and replica calculations

    SciTech Connect

    Whalen, P.P.

    1994-02-01

    The starting point of the Hiroshima-Nagasaki Dose Reevaluation Program is the energy and directional distributions of the prompt neutron and gamma-ray radiation emitted from the exploding bombs. A brief introduction to the neutron source calculations is presented. The development of our current understanding of the source problem is outlined. It is recommended that adjoint calculations be used to modify source spectra to resolve the neutron discrepancy problem.

  2. Investigation of oxygen point defects in cubic ZrO2 by density functional theory

    SciTech Connect

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

    2014-01-01

    The energetics of formation and migration of the oxygen vacancy and interstitial in cubic ZrO2 are investigated by density functional theory calculations. In an O-rich environment, the negatively charged oxygen interstitial is the most dominant defect whereas, the positively charged oxygen vacancy is the most dominant defect under O-poor conditions. Oxygen interstitial migration occurs by the interstitialcy and the direct interstitial mechanisms, with calculated migration energy barriers of 2.94 eV and 2.15 eV, respectively. For the oxygen vacancy, diffusion is preferred along the <100> direction, and the calculated energy barriers are 0.26 eV for , 0.27 eV for and 0.54 eV for . These results indicate that oxygen diffusivity is higher through the vacancy-migration mechanism.

  3. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-05-01

    Archimedes method. The bulk density was 5.029 and 5.57 g/cc for LSFT and dual phase membranes, respectively. The microstructure of the dual phase membrane was analyzed using SEM. It is evident from the micrograph that the microstructure is composed of dual phases. The dense circular regions are enclosed by the less dense, continuous phase which accommodates most of the pores. The pores are normally aggregated and found clustered along the dense regions where as the dense regions do not have pores. Upon closer observation of the micrograph it is revealed that the dense region has a clear circular cleavage or crack as their boundary. The circular cleavage clearly encompasses a dense region and which consists of no pore or any flaw that is visible. The size distribution of the dense, discontinuous regions is varying from 5 to 20 {micro}m with a D{sub 50} of 15 {micro}m. The grain size distribution was estimated from the micrographs using image analysis and a unimodal distribution of grains was observed with an average grain size of 1.99 {micro}m. The chemical compositions of the membranes were analyzed using EDS analysis and no other impurities were observed. The XRD analysis was carried out for the membranes and the phase purity was confirmed. The fracture toughness of LSFT membranes at room temperature has to be calculated using the Vickers indentation method. An electrochemical cell has been designed and built for measurements of the ionic conductivity by the use of blocking electrodes. Preliminary measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} are reported. Modifications to the apparatus to improve the data quality have been completed. Electron microscopy studies of the origin of the slow kinetics on reduction of ferrites have been initiated. 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

  4. Mixed oxygen ion/electron-conducting ceramics for oxygen separation

    SciTech Connect

    Stevenson, J.W.; Armstrong, T.R.; Armstrong, B.L.

    1996-08-01

    Mixed oxygen ion and electron-conducting ceramics are unique materials that can passively separate high purity oxygen from air. Oxygen ions move through a fully dense ceramic in response to an oxygen concentration gradient, charge-compensated by an electron flux in the opposite direction. Compositions in the system La{sub 1{minus}x}M{sub x}Co{sub 1{minus}y{minus}z}Fe{sub y}N{sub z}O{sub 3{minus}{delta}}, perovskites where M=Sr, Ca, and Ba, and N=Mn, Ni, Cu, Ti, and Al, have been prepared and their electrical, oxygen permeation, oxygen vacancy equilibria, and catalytic properties evaluated. Tubular forms, disks, and asymmetric membrane structures, a thin dense layer on a porous support of the same composition, have been fabricated for testing purposes. In an oxygen partial gradient, the passive oxygen flux through fully dense structures was highly dependent on composition. An increase in oxygen permeation with increased temperature is attributed to both enhanced oxygen vacancy mobility and higher vacancy populations. Highly acceptor-doped compositions resulted in oxygen ion mobilities more than an order of magnitude higher than yttria-stabilized zirconia. The mixed conducting ceramics have been utilized in a membrane reactor configuration to upgrade methane to ethane and ethylene. Conditions were established to balance selectivity and throughput in a catalytic membrane reactor constructed from mixed conducting ceramics.

  5. ON-LINE CALCULATOR: FORWARD CALCULATION JOHNSON ETTINGER MODEL

    EPA Science Inventory

    On-Site was developed to provide modelers and model reviewers with prepackaged tools ("calculators") for performing site assessment calculations. The philosophy behind OnSite is that the convenience of the prepackaged calculators helps provide consistency for simple calculations,...

  6. A Comparison of Singlet Oxygen Explicit Dosimetry (SOED) and Singlet Oxygen Luminescence Dosimetry (SOLD) for Photofrin-Mediated Photodynamic Therapy

    PubMed Central

    Kim, Michele M.; Penjweini, Rozhin; Gemmell, Nathan R.; Veilleux, Israel; McCarthy, Aongus; Buller, Gerald S.; Hadfield, Robert H.; Wilson, Brian C.; Zhu, Timothy C.

    2016-01-01

    Accurate photodynamic therapy (PDT) dosimetry is critical for the use of PDT in the treatment of malignant and nonmalignant localized diseases. A singlet oxygen explicit dosimetry (SOED) model has been developed for in vivo purposes. It involves the measurement of the key components in PDT—light fluence (rate), photosensitizer concentration, and ground-state oxygen concentration ([3O2])—to calculate the amount of reacted singlet oxygen ([1O2]rx), the main cytotoxic component in type II PDT. Experiments were performed in phantoms with the photosensitizer Photofrin and in solution using phosphorescence-based singlet oxygen luminescence dosimetry (SOLD) to validate the SOED model. Oxygen concentration and photosensitizer photobleaching versus time were measured during PDT, along with direct SOLD measurements of singlet oxygen and triplet state lifetime (τΔ and τt), for various photosensitizer concentrations to determine necessary photophysical parameters. SOLD-determined cumulative [1O2]rx was compared to SOED-calculated [1O2]rx for various photosensitizer concentrations to show a clear correlation between the two methods. This illustrates that explicit dosimetry can be used when phosphorescence-based dosimetry is not feasible. Using SOED modeling, we have also shown evidence that SOLD-measured [1O2]rx using a 523 nm pulsed laser can be used to correlate to singlet oxygen generated by a 630 nm laser during a clinical malignant pleural mesothelioma (MPM) PDT protocol by using a conversion formula. PMID:27929427

  7. USE OF A PROGRAMMABLE CALCULATOR IN CARDIOPULMONARY PERFUSION.

    PubMed

    Mills, J David; Tallent, Jerome H.

    1978-06-01

    This study describes a hand-held, battery-powered, programmable instrument (Calculator Model SR-52) that can be taken directly into the operating room by cardiopulmonary perfusionists. Three programs are described in detail: 1) Cardiopulmonary perfusion parameters and estimated blood volume; 2) blood gas parameters and saturations, with temperature corrections; and 3) cardiopulmonary oxygen transfer and oxygenator efficiency. This inexpensive calculator allows perfusion personnel to manipulate easily-derived data into values which heretofore have required elaborate nomograms or special slide rules-or were not available within a reasonable computational time.

  8. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; T. Nithyanantham

    2006-12-31

    Ti doping on La{sub 1-x}Sr{sub x}FeO{sub 3-{delta}} (LSF) tends to increase the oxygen equilibration kinetics of LSF in lower oxygen activity environment because of the high valence state of Ti. However, the addition of Ti decreases the total conductivity because the acceptor ([Sr{prime}{sub La}]) is compensated by the donor ([Ti{sub Fe}{sup {sm_bullet}}]) which decreases the carrier concentration. The properties of La{sub 0.2}Sr{sub 0.8}Fe{sub 1-x}Ti{sub x}O{sub 3-{delta}} (LSFT, x = 0.45) have been experimentally and theoretically investigated to elucidate (1) the dependence of oxygen occupancy and electrochemical properties on temperature and oxygen activity by thermogravimetric analysis (TGA) and (2) the electrical conductivity and carrier concentration by Seebeck coefficient and electrical measurements. In the present study, dual phase (La{sub 0.2}Sr{sub 0.8}Fe{sub 0.6}Ti{sub 0.4}O{sub 3-{delta}}/Ce{sub 0.9}Gd{sub 0.1}O{sub 2-{delta}}) membranes have been evaluated for structural properties such as hardness, fracture toughness and flexural strength. The effect of high temperature and slightly reducing atmosphere on the structural properties of the membranes was studied. The flexural strength of the membrane decreases upon exposure to slightly reducing conditions at 1000 C. The as-received and post-fractured membranes were characterized using XRD, SEM and TG-DTA to understand the fracture mechanisms. Changes in structural properties of the composite were sought to be correlated with the physiochemical features of the two-phases. We have reviewed the electrical conductivity data and stoichiometry data for La{sub 0.2}Sr{sub 0.8}Cr{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} some of which was reported previously. Electrical conductivity data for La{sub 0.2}Sr{sub 0.8}Cr{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (LSCrF) were obtained in the temperature range, 752 {approx} 1055 C and in the pO{sub 2} range, 10{sup -18} {approx} 0.5 atm. The slope of the plot of log {sigma} vs

  9. Effects of oxygen adsorption on carbon nanotube field emitters

    NASA Astrophysics Data System (ADS)

    Park, Noejung; Han, Seungwu; Ihm, Jisoon

    2001-09-01

    Effects of oxygen adsorption on the field emission of carbon nanotubes are studied through first-principles calculations. Calculated emission currents are significantly enhanced when oxygen is adsorbed at the tip and the underlying physics is explained in terms of the change in the electronic structure by oxidation and the local field increase at the adsorption site. The issue of the current degradation accompanied by the oxidative etching is also addressed. The field-emission-microscopy images on the phosphor screen are simulated, displaying various patterns characteristic of each adsorption configuration.

  10. Oxygen impurity radiation from Tokamak-like plasmas

    NASA Technical Reports Server (NTRS)

    Rogerson, J. E.; Davis, J.; Jacobs, V. L.

    1977-01-01

    We have constructed a nonhydrodynamic coronal model for calculating radiation from impurity atoms in a heated plasma. Some recent developments in the calculation of dielectronic recombination rate coefficients and collisional excitation rate coefficients are included. The model is applied to oxygen impurity radiation during the first few milliseconds of a TFR Tokamak plasma discharge, and good agreement with experimental results is obtained. Estimates of total line and continuum radiation from the oxygen impurity are given. It is shown that impurity radiation represents a considerable energy loss.

  11. Simultaneous Monitoring of Vascular Oxygenation and Tissue Oxygen Tension of Breast Tumors under Hyperbaric Oxygen Exposure

    DTIC Science & Technology

    2006-04-01

    FOXY system, on various rat breast tumor size (months 14- 30). Instead of single-channel NIRS, steady-state diffuse reflectance spectroscopy (SSDRS...combination of normobaric and hyperbaric oxygen interventions) simultaneously monitored by steady-state diffuse reflectance spectroscopy (SSDRS) and...simultaneously by steady-state diffuse reflectance spectroscopy (SSDRS) and FOXY oxygen sensor in response to normobaric and hyperbaric oxygen

  12. Solar Forbidden Oxygen, Revisited

    NASA Astrophysics Data System (ADS)

    Ayres, Thomas R.

    2008-10-01

    Recent large reductions in the solar oxygen abundance, based on synthesis of photospheric O I, OH, and CO absorptions with 3D convection models, have provoked consternation in the helioseismology community: the previous excellent agreement between measured p-mode oscillation frequencies and predictions based on the recommended epsilonO of a decade ago (680 parts per million [ppm] relative to hydrogen) unravels at the new low value (460 ppm). In an attempt to reconcile these conflicting results, the formation of pivotal [O I] λ6300, which is blended with a weak Ni I line, has been reconsidered, exploiting an alternative 3D model (albeit only a single temporal snapshot). And while there are several areas of agreement with the earlier [O I] studies of Allende Prieto, Asplund, and others, there is one crucial point of disagreement: the epsilonO derived here is significantly larger, 650 +/- 65 ppm (although at the expense of a ~30% weaker Ni I line than expected from the recommended nickel abundance). One innovation is a more robust treatment of the solar wavelengths: the balance between the components of the [O I] + Ni I blend is sensitive to velocity errors of only a few hundred m s-1. A second improvement is enforcement of a "continuum calibration" to ensure a self-consistent 3D temperature scale. Because of the renewed agreement between the linchpin tracer [O I] and seismic oxygen, the proposed downward slump of the solar metallicity and the perceived "oxygen crisis" now can be said to rest on less secure footings.

  13. Vibrational energy relaxation in liquid oxygen

    NASA Astrophysics Data System (ADS)

    Everitt, K. F.; Egorov, S. A.; Skinner, J. L.

    1998-09-01

    We consider theoretically the relaxation from the first excited vibrational state to the ground state of oxygen molecules in neat liquid oxygen. The relaxation rate constant is related in the usual way to the Fourier transform of a certain quantum mechanical force-force time-correlation function. A result from Egelstaff allows one instead to relate the rate constant (approximately) to the Fourier transform of a classical force-force time-correlation function. This Fourier transform is then evaluated approximately by calculating three equilibrium averages from a classical molecular dynamics simulation. Our results for the relaxation times (at two different temperatures) are within a factor of 5 of the experimental relaxation times, which are in the ms range.

  14. Equilibrium Structure of Tantalum Oxygen Clusters

    NASA Astrophysics Data System (ADS)

    Dalgic, S. Sentürk; Caliskan, M.

    2007-04-01

    We determine a refined model for the interionic interactions in TaOn clusters by an analysis of data on their molecular structures. The potential energy function of an ionic cluster we adopt is based on the interionic force model proposed by Akdeniz and Tosi. The microscopic model used for Tantalum oxygen clusters incorporates the Born Model of cohesion and shell model for vibrational motions and crystal defects. Electron shell deformability is described through the effective valences, the electric and overlap polarizabilities of the oxygens, the electric polarizability of the tantalum ions. The two different overlap repulsive energy form have been tested. The molecular structure of clusters in equilibrium have been shown. It has been found in a good agreement for the bond lengths and bond angles by comparing with those obtained by chemical structure calculations and experimental data Thus the applicability of interionic model is tested for transition metal oxide clusters.

  15. Oxygen supplies in disaster management.

    PubMed

    Blakeman, Thomas C; Branson, Richard D

    2013-01-01

    Mass casualty events and disasters, both natural and human-generated, occur frequently around the world and can generate scores of injured or ill victims in need of resources. Of the available medical supplies, oxygen remains the critical consumable resource in disaster management. Strategic management of oxygen supplies in disaster scenarios remains a priority. Hospitals have large supplies of liquid oxygen and a supply of compressed gas oxygen cylinders that allow several days of reserve, but a large influx of patients from a disaster can strain these resources. Most backup liquid oxygen supplies are attached to the main liquid system and supply line. In the event of damage to the main system, the reserve supply is rendered useless. The Strategic National Stockpile supplies medications, medical supplies, and equipment to disaster areas, but it does not supply oxygen. Contracted vendors can deliver oxygen to alternate care facilities in disaster areas, in the form of concentrators, compressed gas cylinders, and liquid oxygen. Planning for oxygen needs following a disaster still presents a substantial challenge, but alternate care facilities have proven to be valuable in relieving pressure from the mass influx of patients into hospitals, especially for those on home oxygen who require only an electrical source to power their oxygen concentrator.

  16. Adsorption of oxygen atom on MoSi2 (110) surface

    NASA Astrophysics Data System (ADS)

    Sun, S. P.; Li, X. P.; Wang, H. J.; Jiang, Y.; Yi, D. Q.

    2016-09-01

    The adsorption energy, structural relaxation and electronic properties of oxygen atom on MoSi2 (110) surface have been investigated by first-principles calculations. The energetic stability of MoSi2 low-index surfaces was analyzed, and the results suggested that MoSi2 (110) surface had energetically stability. The site of oxygen atom adsorbed on MoSi2 (110) surface were discussed, and the results indicated that the preference adsorption site of MoSi2 (110) surface for oxygen atom was H site (hollow position). Our calculated work should help to understand further the interaction between oxygen atoms and MoSi2 surfaces.

  17. Study of argon-oxygen flowing afterglow

    NASA Astrophysics Data System (ADS)

    Mazánková, V.; Trunec, D.; Navrátil, Z.; Raud, J.; Krčma, F.

    2016-06-01

    The reaction kinetics in argon-oxygen flowing afterglow (post-discharge) was studied using NO titration and optical emission spectroscopy. The flowing DC post-discharge in argon-oxygen mixture was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 90 W. The O(3P) atom concentration was determined by NO titration at different places along the flow tube. The optical emission spectra were also measured along the flow tube. Argon spectral lines, oxygen lines at 777 nm and 844.6 nm and atmospheric A-band of {{\\text{O}}2} were identified in the spectra. Rotational temperature of {{\\text{O}}2} was determined from the oxygen atmospheric A-band and also the outer wall temperature of the flow tube was measured by a thermocouple and by an IR thermometer. A zero-dimensional kinetic model for the reactions in the afterglow was developed. This model allows the time dependencies of particle concentrations and of gas temperature to be calculated. The wall recombination probability for O(3P) atoms {γ\\text{O≤ft(\\text{P}\\right)}}=≤ft(1.63+/- 0.06\\right)× {{10}-3} and wall deactivation probability for {{\\text{O}}2} (b {{}1}Σ\\text{g}+ ) molecules {γ{{\\text{O}2}≤ft(\\text{b}\\right)}}=≤ft(1.7+/- 0.1\\right)× {{10}-3} were determined from the fit of model results to experimental data. Sensitivity analysis was applied for the analysis of kinetic model in order to reveal the most important reactions in the model. The calculated gas temperature increases in the afterglow and then decreases at later afterglow times after reaching the maximum. This behavior is in good agreement with the spatial rotational temperature dependence. A similar trend was also observed at outer wall temperature measurement.

  18. Theoretical model for electrophilic oxygen atom insertion into hydrocarbons

    SciTech Connect

    Bach, R.D.; Su, M.D. ); Andres, J.L. Wayne State Univ., Detroit, MI ); McDouall, J.J.W. )

    1993-06-30

    A theoretical model suggesting the mechanistic pathway for the oxidation of saturated-alkanes to their corresponding alcohols and ketones is described. Water oxide (H[sub 2]O-O) is employed as a model singlet oxygen atom donor. Molecular orbital calculations with the 6-31G basis set at the MP2, QCISD, QCISD(T), CASSCF, and MRCI levels of theory suggest that oxygen insertion by water oxide occurs by the interaction of an electrophilic oxygen atom with a doubly occupied hydrocarbon fragment orbital. The electrophilic oxygen approaches the hydrocarbon along the axis of the atomic carbon p orbital comprising a [pi]-[sub CH(2)] or [pi]-[sub CHCH(3)] fragment orbital to form a carbon-oxygen [sigma] bond. A concerted hydrogen migration to an adjacent oxygen lone pair of electrons affords the alcohol insertion product in a stereoselective fashion with predictable stereochemistry. Subsequent oxidation of the alcohol to a ketone (or aldehyde) occurs in a similar fashion and has a lower activation barrier. The calculated (MP4/6-31G*//MP2/6-31G*) activation barriers for oxygen atom insertion into the C-H bonds of methane, ethane, propane, butane, isobutane, and methanol are 10.7, 8.2, 3.9, 4.8, 4.5, and 3.3 kcal/mol, respectively. We use ab initio molecular orbital calculations in support of a frontier MO theory that provides a unique rationale for both the stereospecificity and the stereoselectivity of insertion of electrophilic oxygen and related electrophiles into the carbon-hydrogen bond. 13 refs., 7 figs., 2 tabs.

  19. 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

  20. Calculate waveguide aperture susceptance

    NASA Astrophysics Data System (ADS)

    Kwon, J.-K.; Ishii, T. K.

    1982-12-01

    A method is developed for calculating aperture susceptance which makes use of the distribution of an aperture's local fields. This method can be applied to the computation of the aperture susceptance of irises, as well as the calculation of the susceptances of waveguide filters, aperture antennas, waveguide cavity coupling, waveguide junctions, and heterogeneous boundaries such as inputs to ferrite or dielectric loaded waveguides. This method assumes a local field determined by transverse components of the incident wave in the local surface of the cross section in the discontinuity plane which lies at the aperture. The aperture susceptance is calculated by the use of the local fields, the law of energy conservation, and the principles of continuity of the fields. This method requires that the thickness of the aperture structure be zero, but this does not limit the practical usefulness of this local-field method.

  1. Cluster dynamical mean-field calculations for TiOCl

    NASA Astrophysics Data System (ADS)

    Saha-Dasgupta, T.; Lichtenstein, A.; Hoinkis, M.; Glawion, S.; Sing, M.; Claessen, R.; Valentí, R.

    2007-10-01

    Based on a combination of cluster dynamical mean field theory (DMFT) and density functional calculations, we calculated the angle-integrated spectral density in the layered s=1/2 quantum magnet TiOCl. The agreement with recent photoemission and oxygen K-edge x-ray absorption spectroscopy experiments is found to be good. The improvement achieved with this calculation with respect to previous single-site DMFT calculations is an indication of the correlated nature and low-dimensionality of TiOCl.

  2. Spin Resonance Strength Calculations

    NASA Astrophysics Data System (ADS)

    Courant, E. D.

    2009-08-01

    In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.

  3. Geothermal Life Cycle Calculator

    DOE Data Explorer

    Sullivan, John

    2014-03-11

    This calculator is a handy tool for interested parties to estimate two key life cycle metrics, fossil energy consumption (Etot) and greenhouse gas emission (ghgtot) ratios, for geothermal electric power production. It is based solely on data developed by Argonne National Laboratory for DOE’s Geothermal Technologies office. The calculator permits the user to explore the impact of a range of key geothermal power production parameters, including plant capacity, lifetime, capacity factor, geothermal technology, well numbers and depths, field exploration, and others on the two metrics just mentioned. Estimates of variations in the results are also available to the user.

  4. Graphing Calculator Mini Course

    NASA Technical Reports Server (NTRS)

    Karnawat, Sunil R.

    1996-01-01

    The "Graphing Calculator Mini Course" project provided a mathematically-intensive technologically-based summer enrichment workshop for teachers of American Indian students on the Turtle Mountain Indian Reservation. Eleven such teachers participated in the six-day workshop in summer of 1996 and three Sunday workshops in the academic year. The project aimed to improve science and mathematics education on the reservation by showing teachers effective ways to use high-end graphing calculators as teaching and learning tools in science and mathematics courses at all levels. In particular, the workshop concentrated on applying TI-82's user-friendly features to understand the various mathematical and scientific concepts.

  5. Hyperthermal atomic oxygen generator

    NASA Technical Reports Server (NTRS)

    Khandelwal, Govind S.; Wu, Dongchuan

    1990-01-01

    Characterization of the transport properties of oxygen through silver was continued. Specifically, experiments measuring the transport through Ag(111), Ag(110), Ag(100) single crystals and through Ag0.05 Zr alloy were completed. In addition, experiments using glow discharge excitation of oxygen to assist in the transport were completed. It was found that the permeability through the different orientations of single crystal Ag was the same, but significant differences existed in the diffusivity. The experimental ratio of diffusivities, however, was in reasonable agreement with theoretical estimates. Since the solubilities of orientations must be the same, this suggests some problems with the assumption K = DS. The glow discharge experiments show that there is a substantial increase in transport (factor of six) when the upstream pressure is dissociated to some fraction of atoms (which have a much higher sticking coefficient). These results indicate that there is a significant surface limitation because of dissociative adsorption of the molecules. Experiments with the Ag0.05 Zr alloy and its high-grain boundary and defect density show a permeability of greater than a factor of two over ordinary polycrystalline Ag, but it is unclear as to whether this is because of enhanced transport through these defects or whether the Zr and defects on the surface increased the sticking coefficient and therefore the transport.

  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. Composite oxygen transport membrane

    SciTech Connect

    Lu, Zigui; Plonczak, Pawel J.; Lane, Jonathan A.

    2016-11-08

    A method is described of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. Preferred materials are (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.7Fe.sub.0.3O.sub.3-.delta. for the porous fuel oxidation layer, (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer, and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.3Fe.sub.0.7O.sub.3-.delta. for the porous surface exchange layer. Firing the said fuel activation and separation layers in nitrogen atmosphere unexpectedly allows the separation layer to sinter into a fully densified mass.

  8. Oxygen-Methane Thruster

    NASA Technical Reports Server (NTRS)

    Pickens, Tim

    2012-01-01

    An oxygen-methane thruster was conceived with integrated igniter/injector capable of nominal operation on either gaseous or liquid propellants. The thruster was designed to develop 100 lbf (approximately 445 N) thrust at vacuum conditions and use oxygen and methane as propellants. This continued development included refining the design of the thruster to minimize part count and manufacturing difficulties/cost, refining the modeling tools and capabilities that support system design and analysis, demonstrating the performance of the igniter and full thruster assembly with both gaseous and liquid propellants, and acquiring data from this testing in order to verify the design and operational parameters of the thruster. Thruster testing was conducted with gaseous propellants used for the igniter and thruster. The thruster was demonstrated to work with all types of propellant conditions, and provided the desired performance. Both the thruster and igniter were tested, as well as gaseous propellants, and found to provide the desired performance using the various propellant conditions. The engine also served as an injector testbed for MSFC-designed refractory combustion chambers made of rhenium.

  9. Composite oxygen transport membrane

    DOEpatents

    Christie, Gervase Maxwell; Lane, Jonathan A.

    2016-11-15

    A method of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. In the porous fuel oxidation layer and the optional porous surface exchange layer, A is Calcium and in the dense separation layer A is not Calcium and, preferably is Strontium. Preferred materials are (La.sub.0.8Ca.sub.0.2).sub.0.95Cr.sub.0.5Mn.sub.0.5O.sub.3-.delta. for the porous fuel oxidation and optional porous surface exchange layers and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer. The use of such materials allows the membrane to sintered in air and without the use of pore formers to reduce membrane manufacturing costs. The use of materials, as described herein, for forming the porous layers have application for forming any type of porous structure, such as a catalyst support.

  10. Composite oxygen transport membrane

    DOEpatents

    Christie, Gervase Maxwell; Lane, Jonathan A.

    2014-08-05

    A method of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. In the porous fuel oxidation layer and the optional porous surface exchange layer, A is Calcium and in the dense separation layer A is not Calcium and, preferably is Strontium. Preferred materials are (La.sub.0.8Ca.sub.0.2).sub.0.95Cr.sub.0.5Mn.sub.0.5O.sub.3-.delta. for the porous fuel oxidation and optional porous surface exchange layers and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer. The use of such materials allows the membrane to sintered in air and without the use of pore formers to reduce membrane manufacturing costs. The use of materials, as described herein, for forming the porous layers have application for forming any type of porous structure, such as a catalyst support.

  11. OXYGEN ABUNDANCES IN CEPHEIDS

    SciTech Connect

    Luck, R. E.; Andrievsky, S. M.; Korotin, S. N.; Kovtyukh, V. V. E-mail: serkor@skyline.od.ua E-mail: scan@deneb1.odessa.ua

    2013-07-01

    Oxygen abundances in later-type stars, and intermediate-mass stars in particular, are usually determined from the [O I] line at 630.0 nm, and to a lesser extent, from the O I triplet at 615.7 nm. The near-IR triplets at 777.4 nm and 844.6 nm are strong in these stars and generally do not suffer from severe blending with other species. However, these latter two triplets suffer from strong non-local thermodynamic equilibrium (NLTE) effects and thus see limited use in abundance analyses. In this paper, we derive oxygen abundances in a large sample of Cepheids using the near-IR triplets from an NLTE analysis, and compare those abundances to values derived from a local thermodynamic equilibrium (LTE) analysis of the [O I] 630.0 nm line and the O I 615.7 nm triplet as well as LTE abundances for the 777.4 nm triplet. All of these lines suffer from line strength problems making them sensitive to either measurement complications (weak lines) or to line saturation difficulties (strong lines). Upon this realization, the LTE results for the [O I] lines and the O I 615.7 nm triplet are in adequate agreement with the abundance from the NLTE analysis of the near-IR triplets.

  12. Strain effects on oxygen migration in perovskites.

    PubMed

    Mayeshiba, Tam; Morgan, Dane

    2015-01-28

    Fast oxygen transport materials are necessary for a range of technologies, including efficient and cost-effective solid oxide fuel cells, gas separation membranes, oxygen sensors, chemical looping devices, and memristors. Strain is often proposed as a method to enhance the performance of oxygen transport materials, but the magnitude of its effect and its underlying mechanisms are not well-understood, particularly in the widely-used perovskite-structured oxygen conductors. This work reports on an ab initio prediction of strain effects on migration energetics for nine perovskite systems of the form LaBO3, where B = [Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ga]. Biaxial strain, as might be easily produced in epitaxial systems, is predicted to lead to approximately linear changes in migration energy. We find that tensile biaxial strain reduces the oxygen vacancy migration barrier across the systems studied by an average of 66 meV per percent strain for a single selected hop, with a low of 36 and a high of 89 meV decrease in migration barrier per percent strain across all systems. The estimated range for the change in migration barrier within each system is ±25 meV per percent strain when considering all hops. These results suggest that strain can significantly impact transport in these materials, e.g., a 2% tensile strain can increase the diffusion coefficient by about three orders of magnitude at 300 K (one order of magnitude at 500 °C or 773 K) for one of the most strain-responsive materials calculated here (LaCrO3). We show that a simple elasticity model, which assumes only dilative or compressive strain in a cubic environment and a fixed migration volume, can qualitatively but not quantitatively model the strain dependence of the migration energy, suggesting that factors not captured by continuum elasticity play a significant role in the strain response.

  13. 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

  14. Measurement of oxygen saturation in small retinal vessels with adaptive optics confocal scanning laser ophthalmoscope.

    PubMed

    Li, Hao; Lu, Jing; Shi, Guohua; Zhang, Yudong

    2011-11-01

    We have used an adaptive optics confocal scanning laser ophthalmoscope to assess oxygen saturation in small retinal vessels. Images of the vessels with a diameter smaller than 50 μm are recorded at oxygen sensitive and isosbestic wavelengths (680 and 796 nm, respectively). The vessel optical densities (ODs) are determined by a computer algorithm. Then, OD ratios (ODRs), which are inversely proportional to oxygen saturation, are calculated. The results show that arterial ODRs are significantly smaller than venous ODRs, indicating that oxygen saturation in the artery is higher than that in the vein. To the best of our knowledge, this is the first noninvasive measurement of oxygen saturation in small retinal vessels.

  15. Deciphering mechanisms of enhanced-retarded oxygen diffusion in doped Si

    NASA Astrophysics Data System (ADS)

    Timerkaeva, Dilyara; Caliste, Damien; Pochet, Pascal

    2013-12-01

    We study enhanced/retarded diffusion of oxygen in doped silicon by means of first principle calculations. We evidence that the migration energy of oxygen dimers cannot be significantly affected by strain, doping type, or concentration. We attribute the enhanced oxygen diffusion in p-doped silicon to reduced monomer migration energy and the retarded oxygen diffusion in Sb-doped to monomer trapping close to a dopant site. These two mechanisms can appear simultaneously for a given dopant leading to contradictory experimental results. More generally, our findings cast a new light on phenomena involving oxygen diffusion: precipitation, thermal donors formation, and light induced degradation.

  16. Increase in whole-body peripheral vascular resistance during three hours of air or oxygen prebreathing

    NASA Technical Reports Server (NTRS)

    Waligora, J. M.; Horrigan, D. J., Jr.; Conkin, J.; Dierlam, J. J.; Stanford, J., Jr.; Riddle, J. R.

    1984-01-01

    Male and female subjects prebreathed air or 100% oxygen through a mask for 3.0 hours while comfortably reclined. Blood pressures, heart rate, and cardiac output were collected before and after the prebreathe. Peripheral vascular resistance (PVR) was calculated from these parameters and increased by 29% during oxygen prebreathing and 15% during air prebreathing. The oxygen contributed substantially to the increase in PVR. Diastolic blood pressure increased by 18% during the oxygen prebreathe while stystolic blood pressure showed no change under either procedure. The increase in PVR during air prebreathing was attributed to procedural stress common to air and oxygen prebreathing.

  17. A program for calculation of intrapulmonary shunts, blood-gas and acid-base values with a programmable calculator.

    PubMed

    Ruiz, B C; Tucker, W K; Kirby, R R

    1975-01-01

    With a desk-top, programmable calculator, it is now possible to do complex, previously time-consuming computations in the blood-gas laboratory. The authors have developed a program with the necessary algorithms for temperature correction of blood gases and calculation of acid-base variables and intrapulmonary shunt. It was necessary to develop formulas for the Po2 temperature-correction coefficient, the oxyhemoglobin-dissociation curve for adults (withe necessary adjustments for fetal blood), and changes in water vapor pressure due to variation in body temperature. Using this program in conjuction with a Monroe 1860-21 statistical programmable calculator, it is possible to temperature-correct pH,Pco2, and Po2. The machine will compute alveolar-arterial oxygen tension gradient, oxygen saturation (So2), oxygen content (Co2), actual HCO minus 3 and a modified base excess. If arterial blood and mixed venous blood are obtained, the calculator will print out intrapulmonary shunt data (Qs/Qt) and arteriovenous oxygen differences (a minus vDo2). There also is a formula to compute P50 if pH,Pco2,Po2, and measured So2 from two samples of tonometered blood (one above 50 per cent and one below 50 per cent saturation) are put into the calculator.

  18. Fires and Burns Involving Home Medical Oxygen

    MedlinePlus

    ... nfpa.org Fires and Burns Involving Home Medical Oxygen The air is normally 21% oxygen. Oxygen is not flammable, but fire needs it to burn. ¾ When more oxygen is present, any fire that starts will burn ...

  19. Airborne antenna pattern calculations

    NASA Technical Reports Server (NTRS)

    Bagherian, A. B.; Mielke, R. R.

    1983-01-01

    Use of calculation program START and modeling program P 3D to produce radiation patterns of antennas mounted on a space station is discussed. Basic components of two space stations in the early design stage are simulated and radiation patterns for antennas mounted on the modules are presented.

  20. Solar Guide and Calculator.

    ERIC Educational Resources Information Center

    Mazria, Edward; Winitsky, David

    This guide provides users with a basic understanding of where and how the sun works in relation to a building and site and provides a simplified method of calculating sun angles and the available heat energy from the sun on vertical and horizontal surfaces. (Author/IRT)

  1. A Computer Calculated Index.

    ERIC Educational Resources Information Center

    Brown, Francis J.

    The Gunning Fog Index of readability indicates both the average length of words and the difficult words (three or more syllables) in written material. This document describes a business communication course at Wayne State University in which students calculate the Gunning Fog Index of two of their writing assignments with the aid of the…

  2. Airborne antenna pattern calculations

    NASA Technical Reports Server (NTRS)

    Knerr, T. J.; Owens, T. M.; Mielke, R. R.

    1981-01-01

    Calculated principal-and off-principal plane patterns are presented for the following aircraft: de Havilland DHC-7, Rockwell Sabreliner 75A, Piper PA-31T Cheyenne, Lockheed Jet Star II, Piper PA-31-350 Navajo Chieftain, Beechcraft Duke B60, Rockwell Commander 700, Cessna Citation 3, Piper PA-31P Pressurized Navajo, Lear Jet, and Twin Otter DHC-6.

  3. Calculation of enviromental indices

    SciTech Connect

    1995-10-01

    This portion of the Energy Vision 2020 draft report discusses the development of environmental indices. These indices were developed to be a quantitative measure of characterizing how TVA power system operations and alternative energy strategies might affect the environment. All indices were calculated relative to the reference strategy, and for the environmental review, the reference strategy was `no action`.

  4. Tunnel closure calculations

    SciTech Connect

    Moran, B.; Attia, A.

    1995-07-01

    When a deeply penetrating munition explodes above the roof of a tunnel, the amount of rubble that falls inside the tunnel is primarily a function of three parameters: first the cube-root scaled distance from the center of the explosive to the roof of the tunnel. Second the material properties of the rock around the tunnel, and in particular the shear strength of that rock, its RQD (Rock Quality Designator), and the extent and orientation of joints. And third the ratio of the tunnel diameter to the standoff distance (distance between the center of explosive and the tunnel roof). The authors have used CALE, a well-established 2-D hydrodynamic computer code, to calculate the amount of rubble that falls inside a tunnel as a function of standoff distance for two different tunnel diameters. In particular they calculated three of the tunnel collapse experiments conducted in an iron ore mine near Kirkeness, Norway in the summer of 1994. The failure model that they used in their calculations combines an equivalent plastic strain criterion with a maximum tensile strength criterion and can be calibrated for different rocks using cratering data as well as laboratory experiments. These calculations are intended to test and improve the understanding of both the Norway Experiments and the ACE (Array of conventional Explosive) phenomenology.

  5. Plutonium 239 Equivalency Calculations

    SciTech Connect

    Wen, J

    2011-05-31

    This document provides the basis for converting actual weapons grade plutonium mass to a plutonium equivalency (PuE) mass of Plutonium 239. The conversion can be accomplished by performing calculations utilizing either: (1) Isotopic conversions factors (CF{sub isotope}), or (2) 30-year-old weapons grade conversion factor (CF{sub 30 yr}) Both of these methods are provided in this document. Material mass and isotopic data are needed to calculate PuE using the isotopic conversion factors, which will provide the actual PuE value at the time of calculation. PuE is the summation of the isotopic masses times their associated isotopic conversion factors for plutonium 239. Isotopic conversion factors are calculated by a normalized equation, relative to Plutonium 239, of specific activity (SA) and cumulated dose inhalation affects based on 50-yr committed effective dose equivalent (CEDE). The isotopic conversion factors for converting weapons grade plutonium to PuE are provided in Table-1. The unit for specific activity (SA) is curies per gram (Ci/g) and the isotopic SA values come from reference [1]. The cumulated dose inhalation effect values in units of rem/Ci are based on 50-yr committed effective dose equivalent (CEDE). A person irradiated by gamma radiation outside the body will receive a dose only during the period of irradiation. However, following an intake by inhalation, some radionuclides persist in the body and irradiate the various tissues for many years. There are three groups CEDE data representing lengths of time of 0.5 (D), 50 (W) and 500 (Y) days, which are in reference [2]. The CEDE values in the (W) group demonstrates the highest dose equivalent value; therefore they are used for the calculation.

  6. Guide for Oxygen Compatibility Assessments on Oxygen Components and Systems

    NASA Technical Reports Server (NTRS)

    Rosales, Keisa R.; Shoffstall, Michael S.; Stoltzfus, Joel M.

    2007-01-01

    Understanding and preventing fire hazards is necessary when designing, maintaining, and operating oxygen systems. Ignition risks can be minimized by controlling heat sources and using materials that will not ignite or will not support burning in the end-use environment. Because certain materials are more susceptible to ignition in oxygen-enriched environments, a compatibility assessment should be performed before the component is introduced into an oxygen system. This document provides an overview of oxygen fire hazards and procedures that are consistent with the latest versions of American Society for Testing and Materials (ASTM) Standards G63 (1999) and G94 (2005) to address fire hazards associated with oxygen systems. This document supersedes the previous edition, NASA Technical Memorandum 104823, Guide for Oxygen Hazards Analyses on Components and Systems (1996). The step-by-step oxygen compatibility assessment method described herein (see Section 4) enables oxygen-system designers, system engineers, and facility managers to determine areas of concern with respect to oxygen compatibility and, ultimately, prevent damage to a system or injury to personnel.

  7. 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

    2004-05-01

    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, in situ neutron diffraction was used to characterize the chemical and structural properties of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} (here after as L2SF55T) specimen, which was subject to measurements of neutron diffraction from room temperature to 900 C. It was found that space group of R3c yielded a better refinement than a cubic structure of Pm3m. Oxygen occupancy was nearly 3 in the region from room temperature to 700 C, above which the occupancy decreased due to oxygen loss. Dense OTM bars provided by Praxair were loaded to fracture at varying stress rates. Studies were done at room temperature in air and at 1000 C in a specified environment to evaluate slow crack growth behavior. The X-Ray data and fracture mechanisms points to non-equilibrium decomposition of the LSFCO OTM membrane. The non-equilibrium conditions could probably be due to the nature of the applied stress field (stressing rates) and leads to transition in crystal structures and increased kinetics of decomposition. The formations of a Brownmillerite or Sr2Fe2O5 type structures, which are orthorhombic are attributed to the ordering of oxygen vacancies. The cubic to orthorhombic transitions leads to 2.6% increase in strains and thus residual stresses generated could influence the fracture behavior of the OTM membrane. Continued investigations on the thermodynamic properties (stability and phase-separation behavior) and total conductivity of prototype membrane materials were carried out. The data are needed together with the kinetic information to develop a complete model for the membrane transport. Previously characterization, stoichiometry and conductivity measurements for samples of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} were reported. In this report

  8. Combined radiation-protective and radiation-sensitizing agents. II. Radiosensitivity of hypoxic or aerobic Chinese hamster fibroblasts in the presence of cysteamine and misonidazole: implications for the oxygen effect (with Appendix on calculation of dose-modifying factors. [/sup 60/Co

    SciTech Connect

    Koch, C.J.; Howell, R.L.

    1981-08-01

    Experiments have been done to test whether a hypoxic cell radiosensitizing agent (misonidazole) can be combined with a radioprotecting agent (cysteamine) to equalize partially the radiation response of hypoxic and aerobic mammalian cells in tissue culture. The results indicate that cysteamine will protect against the radiosensitization of a hypoxic cell sensitizing drug (2.5 mM misonidazole) at much lower concentration than it will protect against the radiosensitization of oxygen (350 ..mu..M). Thus the addition of a radiation-protective drug tends to cancel the drug benefit of the radiosensitizer and therefore increases the differential response of hypoxic and aerobic cells rather than equalizing this response. The data suggest that even in situations where tumor tissue absorbs far less radioprotective drug than normal tissue (e.g., WR 2721), one might expect difficulties with the simultaneous administration of radiosensitizing and radioprotecting drugs.

  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. The oxygen isotopes

    NASA Astrophysics Data System (ADS)

    Brown, B. Alex

    The properties of the oxygen isotopes provide diverse examples of progress made in experiments and theory. This chain of isotopes has been studied from beyond the proton drip line in 12O to beyond the neutron drip line in 25,26O. This short survey starts with the microscopic G matrix approach for 18O of Kuo and Brown in the 1960’s and shows how theory has evolved. The nuclear structure around the doubly-magic nucleus 24O is particularly simple in terms of the nuclear shell model. The nuclear structure around the doubly-magic nucleus 16O exhibits the coexistence of single-particle and collective structure.

  11. Oxygen abundance and convection

    NASA Astrophysics Data System (ADS)

    Van't Veer, C.; Cayrel, R.

    The triplet IR lines of O I near 777 nm are computed with the Kurucz's code, modified to accept several convection models. The program has been run with the MLT algorithm, with l/H = 1.25 and 0.5, and with the Canuto-Mazzitelli and Canuto-Goldman-Mazzitelli approaches, on a metal-poor turnoff-star model atmosphere with Teff=6200 K, log g = 4.3, [Fe/H]= -1.5. The results show that the differences in equivalent widths for the 4 cases do not exceed 2 per cent (0.3 mA). The convection treatment is therefore not an issue for the oxygen abundance derived from the permitted lines.

  12. 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

  13. A Small Oxygen Concentrator

    DTIC Science & Technology

    1985-12-01

    150- S40- 20- 10 0 0 10 i0 30 40 NUIT PRESS=R (psig Figure 7. Percentage of oxygen. versus inlet pressure when using Soc with 131 molecular s ieve. 70...chick valve ano *move the plunger and spring. Disca the plunger; the spring will W• reused. Mill a SS sleeve to 0.535" 0.0. and 0.50" I.D. and press tit...the fjur 1" caps. The i n- side of two of the caps is milled flat to a diameteýr of 7/8". P-Kace one ena of a 10’, length of 1/2" SS tube in each Of

  14. Microdistribution of oxygen in silicon

    NASA Technical Reports Server (NTRS)

    Murgai, A.; Chi, J. Y.; Gatos, H. C.

    1980-01-01

    The microdistribution of oxygen in Czochralskii-grown, p-type silicon crystals was determined by using the SEM in the EBIC mode in conjunction with spreading resistance measurements. When the conductivity remained p-type, bands of contrast were observed in the EBIC image which corresponded to maxima in resistivity. When at the oxygen concentration maxima the oxygen donor concentration exceeded the p-type dopant concentration, an inversion of the conductivity occurred. It resulted in the formation of p-n junctions in a striated configuration and the local inversion of the EBIC image contrast. By heat-treating silicon at 1000 C prior to the activation of oxygen donors, some silicon-oxygen micro-precipitates were observed in the EBIC image within the striated oxygen concentration maxima.

  15. Calculation of effective dose.

    PubMed

    McCollough, C H; Schueler, B A

    2000-05-01

    The concept of "effective dose" was introduced in 1975 to provide a mechanism for assessing the radiation detriment from partial body irradiations in terms of data derived from whole body irradiations. The effective dose is the mean absorbed dose from a uniform whole-body irradiation that results in the same total radiation detriment as from the nonuniform, partial-body irradiation in question. The effective dose is calculated as the weighted average of the mean absorbed dose to the various body organs and tissues, where the weighting factor is the radiation detriment for a given organ (from a whole-body irradiation) as a fraction of the total radiation detriment. In this review, effective dose equivalent and effective dose, as established by the International Commission on Radiological Protection in 1977 and 1990, respectively, are defined and various methods of calculating these quantities are presented for radionuclides, radiography, fluoroscopy, computed tomography and mammography. In order to calculate either quantity, it is first necessary to estimate the radiation dose to individual organs. One common method of determining organ doses is through Monte Carlo simulations of photon interactions within a simplified mathematical model of the human body. Several groups have performed these calculations and published their results in the form of data tables of organ dose per unit activity or exposure. These data tables are specified according to particular examination parameters, such as radiopharmaceutical, x-ray projection, x-ray beam energy spectra or patient size. Sources of these organ dose conversion coefficients are presented and differences between them are examined. The estimates of effective dose equivalent or effective dose calculated using these data, although not intended to describe the dose to an individual, can be used as a relative measure of stochastic radiation detriment. The calculated values, in units of sievert (or rem), indicate the amount of

  16. Saturn's Stratospheric Oxygen Compounds

    NASA Astrophysics Data System (ADS)

    Romani, Paul N.; Delgado Díaz, Héctor E.; Bjoraker, Gordon; Hesman, Brigette; Achterberg, Richard

    2016-10-01

    There are three known oxygenated species present in Saturn's upper atmosphere: H2O, CO and CO2. The ultimate source of the water must be external to Saturn as Saturn's cold tropopause effectively prevents any internal water from reaching the upper atmosphere. The carbon monoxide and dioxide source(s) could be internal, external, produced by the photochemical interaction of water with Saturn's stratospheric hydrocarbons or some combination of all of these. At this point it is not clear what the external source(s) are.Cassini's Composite InfraRed Spectrometer (CIRS) has detected emission lines of H2O and CO2 (Hesman et al., DPS 2015, 311.16 & Abbas et al. 2013, Ap. J. doi:10.1088/0004-637X/776/2/73) on Saturn. CIRS also retrieves the temperature of the stratosphere using CH4 lines at 7.7 microns. Using CIRS retrieved temperatures, the mole fraction of H2O at the 0.5-5 mbar level can be retrieved and the CO2 mole fraction at ~1-10 mbar. Coupled with ground based observations of CO (Cavalié et al., 2010, A&A, DOI: 10.1051/0004-6361/200912909) these observations provide a complete oxygen compound data set to test photochemical models.Preliminary results will be presented with an emphasis on upper limit analysis to determine the percentage of stratospheric CO and CO2 that can be produced photochemically from CIRS observational constraints on the H2O profile.

  17. 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.

  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. Modelling the effects of cerebral microvasculature morphology on oxygen transport.

    PubMed

    Park, Chang Sub; Payne, Stephen J

    2016-01-01

    The cerebral microvasculature plays a vital role in adequately supplying blood to the brain. Determining the health of the cerebral microvasculature is important during pathological conditions, such as stroke and dementia. Recent studies have shown the complex relationship between cerebral metabolic rate and transit time distribution, the transit times of all the possible pathways available dependent on network topology. In this paper, we extend a recently developed technique to solve for residue function, the amount of tracer left in the vasculature at any time, and transit time distribution in an existing model of the cerebral microvasculature to calculate cerebral metabolism. We present the mathematical theory needed to solve for oxygen concentration followed by results of the simulations. It is found that oxygen extraction fraction, the fraction of oxygen removed from the blood in the capillary network by the tissue, and cerebral metabolic rate are dependent on both mean and heterogeneity of the transit time distribution. For changes in cerebral blood flow, a positive correlation can be observed between mean transit time and oxygen extraction fraction, and a negative correlation between mean transit time and metabolic rate of oxygen. A negative correlation can also be observed between transit time heterogeneity and the metabolic rate of oxygen for a constant cerebral blood flow. A sensitivity analysis on the mean and heterogeneity of the transit time distribution was able to quantify their respective contributions to oxygen extraction fraction and metabolic rate of oxygen. Mean transit time has a greater contribution than the heterogeneity for oxygen extraction fraction. This is found to be opposite for metabolic rate of oxygen. These results provide information on the role of the cerebral microvasculature and its effects on flow and metabolism. They thus open up the possibility of obtaining additional valuable clinical information for diagnosing and treating

  20. Thermodynamic calculations and analysis of the deoxidation of special alloys by strong deoxidizers and carbon in vacuum

    NASA Astrophysics Data System (ADS)

    Sisev, A. A.; Paderin, S. N.; Troyanov, K. V.

    2015-06-01

    The thermodynamic calculations of the equilibrium activities of oxygen with deoxidizers Al, Ca, Mg, Ti, La, and Ce are performed from the compositions of metal samples taken during melting of special alloys in a vacuum induction furnace. The emf was measured simultaneously with sampling during the immersion of an oxygen sensor into a liquid metal. The results of calculations of the equilibrium oxygen activities with each deoxidizer are compared to the oxygen activities calculated by the measured values of emf and the temperature metal.

  1. Radioprotection calculations for MEGAPIE.

    PubMed

    Zanini, L

    2005-01-01

    The MEGAwatt PIlot Experiment (MEGAPIE) liquid lead-bismuth spallation neutron source will commence operation in 2006 at the SINQ facility of the Paul Scherrer Institut. Such an innovative system presents radioprotection concerns peculiar to a liquid spallation target. Several radioprotection issues have been addressed and studied by means of the Monte Carlo transport code, FLUKA. The dose rates in the room above the target, where personnel access may be needed at times, from the activated lead-bismuth and from the volatile species produced were calculated. Results indicate that the dose rate level is of the order of 40 mSv h(-1) 2 h after shutdown, but it can be reduced below the mSv h(-1) level with slight modifications to the shielding. Neutron spectra and dose rates from neutron transport, of interest for possible damage to radiation sensitive components, have also been calculated.

  2. Hot oxygen corona of Mars

    SciTech Connect

    Ip, W.H.

    1988-10-01

    Electron dissociative recombination of O2(+) ions in the Venus ionosphere, which may be an important source of suprathermal atomic oxygen, is presently considered as a factor in the Mars exosphere; due to the weaker surface gravitational attraction of Mars, a hot oxygen corona thus formed would be denser than that of Venus at altitudes greater than 2000 km despite Mars' lower ionospheric content. If such an extended oxygen corona does exist on Mars, its collisional interaction with Phobos would lead to the formation of an oxygen gas torus whose average number density is of the order of only 1-2/cu cm along the Phobos orbit. 51 references.

  3. 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

  4. CONVEYOR FOUNDATIONS CALCULATION

    SciTech Connect

    S. Romanos

    1995-03-10

    The purpose of these calculations is to design foundations for all conveyor supports for the surface conveyors that transport the muck resulting from the TBM operation, from the belt storage to the muck stockpile. These conveyors consist of: (1) Conveyor W-TO3, from the belt storage, at the starter tunnel, to the transfer tower. (2) Conveyor W-SO1, from the transfer tower to the material stacker, at the muck stockpile.

  5. PIC: Protein Interactions Calculator

    PubMed Central

    Tina, K. G.; Bhadra, R.; Srinivasan, N.

    2007-01-01

    Interactions within a protein structure and interactions between proteins in an assembly are essential considerations in understanding molecular basis of stability and functions of proteins and their complexes. There are several weak and strong interactions that render stability to a protein structure or an assembly. Protein Interactions Calculator (PIC) is a server which, given the coordinate set of 3D structure of a protein or an assembly, computes various interactions such as disulphide bonds, interactions between hydrophobic residues, ionic interactions, hydrogen bonds, aromatic–aromatic interactions, aromatic–sulphur interactions and cation–π interactions within a protein or between proteins in a complex. Interactions are calculated on the basis of standard, published criteria. The identified interactions between residues can be visualized using a RasMol and Jmol interface. The advantage with PIC server is the easy availability of inter-residue interaction calculations in a single site. It also determines the accessible surface area and residue-depth, which is the distance of a residue from the surface of the protein. User can also recognize specific kind of interactions, such as apolar–apolar residue interactions or ionic interactions, that are formed between buried or exposed residues or near the surface or deep inside. PMID:17584791

  6. PIC: Protein Interactions Calculator.

    PubMed

    Tina, K G; Bhadra, R; Srinivasan, N

    2007-07-01

    Interactions within a protein structure and interactions between proteins in an assembly are essential considerations in understanding molecular basis of stability and functions of proteins and their complexes. There are several weak and strong interactions that render stability to a protein structure or an assembly. Protein Interactions Calculator (PIC) is a server which, given the coordinate set of 3D structure of a protein or an assembly, computes various interactions such as disulphide bonds, interactions between hydrophobic residues, ionic interactions, hydrogen bonds, aromatic-aromatic interactions, aromatic-sulphur interactions and cation-pi interactions within a protein or between proteins in a complex. Interactions are calculated on the basis of standard, published criteria. The identified interactions between residues can be visualized using a RasMol and Jmol interface. The advantage with PIC server is the easy availability of inter-residue interaction calculations in a single site. It also determines the accessible surface area and residue-depth, which is the distance of a residue from the surface of the protein. User can also recognize specific kind of interactions, such as apolar-apolar residue interactions or ionic interactions, that are formed between buried or exposed residues or near the surface or deep inside.

  7. The ancient oxygen exosphere of Mars - Implications for atmosphere evolution

    NASA Astrophysics Data System (ADS)

    Zhang, M. H. G.; Luhmann, J. G.; Bougher, S. W.; Nagy, A. F.

    1993-06-01

    The paper considers absorption of oxygen (atoms and ions) by the surface as a mechanism for the early Martian atmosphere escape, due to the effect of high EUV flux of the ancient sun. Hot oxygen exosphere densities in ancient atmosphere and ionosphere are calculated for different EUV fluxes and the escape fluxes associated with these exposures. Using these densities, the ion production rate above the ionopause is calculated for different epochs including photoionization, charge exchange, and solar wind electron impact. It is found that, when the inferred high solar EUV fluxes of the past are taken into account, oxygen equivalent to that in several tens of meters of water, planet-wide, should have escaped Martian atmosphere to space over the last 3 Gyr.

  8. Influence of oxygen impurity on electronic properties of carbon and boron nitride nanotubes: A comparative study

    SciTech Connect

    Singh, Ram Sevak

    2015-11-15

    Influence of oxygen impurity on electronic properties of carbon and boron nitride nanotubes (CNTs and BNNTs) is systematically studied using first principle calculations based on density functional theory. Energy band structures and density of states of optimized zigzag (5, 0), armchair (3, 3), and chiral (4, 2) structures of CNT and BNNT are calculated. Oxygen doping in zigzag CNT exhibits a reduction in metallicity with opening of band gap in near-infrared region while metallicity is enhanced in armchair and chiral CNTs. Unlike oxygen-doped CNTs, energy bands are drastically modulated in oxygen-doped zigzag and armchair BNNTs, showing the nanotubes to have metallic behaviour. Furthermore, oxygen impurity in chiral BNNT induces narrowing of band gap, indicating a gradual modification of electronic band structure. This study underscores the understanding of different electronic properties induced in CNTs and BNNTs under oxygen doping, and has potential in fabrication of various nanoelectronic devices.

  9. Thermodynamic, transport, and flow properties of gaseous products resulting from combustion of methane-air-oxygen

    NASA Technical Reports Server (NTRS)

    Klich, G. F.

    1976-01-01

    Results of calculations to determine thermodynamic, transport, and flow properties of combustion product gases are presented. The product gases are those resulting from combustion of methane-air-oxygen and methane-oxygen mixtures. The oxygen content of products resulting from the combustion of methane-air-oxygen mixtures was similiar to that of air; however, the oxygen contained in products of methane-oxygen combustion ranged from 20 percent by volume to zero for stoichiometric combustion. Calculations were made for products of reactant mixtures with fuel percentages, by mass, of 7.5 to 20. Results are presented for specific mixtures for a range of pressures varying from 0.0001 to 1,000 atm and for temperatures ranging from 200 to 3,800 K.

  10. Oxygenation mechanism of ions in dynamic reaction cell ICP-MS.

    PubMed

    Narukawa, Tomohiro; Chiba, Koichi

    2013-01-01

    A dynamic reaction cell (DRC) is one of the most effective tools for eliminating spectral interferences caused by polyatomic molecules in inductively coupled plasma mass spectrometry (ICP-MS). Oxygen gas (O2), by producing oxygenated ions, is very effective in reducing some specific spectral interferences. In this study, the oxygenation of elemental ions (M(+)) in the DRC was investigated experimentally, and a new explanation for oxygenation based on the enthalpy changes in the oxygenating reactions is proposed. The enthalpy changes of each M(+) were calculated and the possibility of each reaction occurring was evaluated. The calculations were in good agreement with experimental observations. Theoretical and experimental results supported the hypothesis that the enthalpy changes (ΔH) of M(+)+ O2 → MO(+) + O and M(+) + O → MO(+) and the thermodynamic stability of M(+)-O are key factors controlling oxygenation of M(+) in the DRC.

  11. Distribution of thermal oxygen ions in the near earth magnetosphere

    NASA Astrophysics Data System (ADS)

    Liu, W.; Cao, J.

    2013-12-01

    Based on eleven years of Cluster particle observations, we investigate the distribution of thermal oxygen ions in the near earth magnetosphere with full spatial coverage between 4 to 20 Re. Averaged oxygen ion fluxes are calculated for three energy ranges (E1: 25-136eV; E2: 136eV-3keV; E3 3-35keV) based on measurements from CIS instrument. In a preliminary analysis, we found that oxygen ions of E1 energy are observed mostly in the Polar Regions flowing toward the nightside with average speed of ~20 km/s at 5 Re. They are accelerated to E2 energy range before they arrive at plasmasheet. Clear dawn-dusk asymmetry is observed in the plasmasheet for oxygen ions of the E1 and E2 energy that they are distributed beyond 10 Re on the duskside and beyond 15 Re on the dawnside, suggesting the transportation from ionosphere to plasmasheet is asymmetric for dawn and dusk sides. These oxygen ions are further accelerated in the plasmasheet to E3 energy range and are transported toward the Earth, while they drift westward. These oxygen ions finally reach the dayside, and then either return to the ionosphere or escape from the dayside magnetopause to magnetosheeth. This study provides background knowledge on complete distribution of thermal oxygen ions in the near earth magnetosphere for the modelling and simulation studies on ionosphere-magnetosphere coupling.

  12. Inhomogeneous depletion of oxygen ions in metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Vykhodets, Vladimir B.; Jarvis, Emily A. A.; Kurennykh, Tatiana E.; Beketov, Igor V.; Obukhov, Sviatoslav I.; Samatov, Oleg M.; Medvedev, Anatoly I.; Davletshin, Andrey E.; Whyte, Travis H.

    2016-02-01

    Zirconia and yttria stabilized zirconia (YSZ) have multiple uses, including catalysis, fuel cells, dental applications, and thermal coatings. We employ nuclear reaction analysis to determine elemental composition of YSZ nanoparticles synthesized by laser evaporation including 18O studies to distinguish between oxide and adsorbed oxygen content as a function of surface area. We see dramatic deviation from stoichiometry that can be traced to loss of oxygen from the oxide near the surface of these nanopowders. Density functional calculations are coupled with these experimental studies to explore the electronic structure of nonstoichiometric surfaces achieved through depletion of oxygen. Our results show oxygen-depleted surfaces present under oxygen potentials where stoichiometric, oxygen-terminated surfaces would be favored thermodynamically for crystalline systems. Oxygen depletion at nanopowder surfaces can create effective two-dimensional surface metallic states while maintaining stoichiometry in the underlying nanoparticle core. This insight into nanopowder surfaces applies to dissimilar oxides of aluminum and zirconium indicating synthesis conditions may be more influential than the inherent oxide properties and displaying need for distinct models for nanopowders of these important engineering materials where surface chemistry dominates performance.

  13. Angular distribution of photoelectrons from atomic oxygen, nitrogen, and carbon

    NASA Technical Reports Server (NTRS)

    Manson, S. T.; Kennedy, D. J.; Starace, A. F.; Dill, D.

    1974-01-01

    The angular distribution of photoelectrons from atomic oxygen is investigated using Hartree-Fock (HF) wave functions. The correct formulation is used to compare HS and HF results. Agreement between these results is good and the HS calculations have been extended to atomic nitrogen and carbon as well.

  14. Greatly facilitated oxygen vacancy formation in ceria nanocrystallites.

    PubMed

    Migani, Annapaola; Vayssilov, Georgi N; Bromley, Stefan T; Illas, Francesc; Neyman, Konstantin M

    2010-08-28

    The formation of oxygen vacancies in nanoparticles Ce(n)O(2n) (n < or = 80), studied using density-functional calculations, is found to be greatly facilitated compared to extended surfaces, which explains the observed spectacular reactivity of nanostructured ceria.

  15. Recirculation in venovenous extracorporeal membrane oxygenation.

    PubMed

    Xie, Ashleigh; Yan, Tristan D; Forrest, Paul

    2016-12-01

    Despite the increasing use of venovenous extracorporeal membrane oxygenation (ECMO) to treat severe respiratory failure, recirculation remains a common complication that may result in severe hypoxemia and end-organ damage. The present review, therefore, examines updated evidence for the causes, measurement, and management of recirculation. Six electronic databases were searched from their dates of inception to January 2016, and 38 relevant studies were selected for analysis. This review revealed that, currently, recirculation is typically calculated from measurement of blood oxygen saturations, although limited evidence suggests that oxygen content may provide a more accurate measure. Dilutional ultrasound may play an additional role in dynamic quantitative monitoring of recirculation, but further human studies are required to validate its clinical use. Although cannula configuration appears to be a key contributor to recirculation in addition to factors such as ECMO flow rate, there are insufficient comparative clinical studies to recommend an optimal cannulation technique for minimizing recirculation. Existing evidence suggests that the dual-lumen cannula may have a low recirculation fraction, but only if correctly positioned. This review underscores the need for more robust clinical and laboratory studies to effectively evaluate and address the persistent problem of recirculation.

  16. Atomic oxygen in the Martian thermosphere

    NASA Technical Reports Server (NTRS)

    Stewart, A. I. F.; Alexander, M. J.; Meier, R. R.; Paxton, L. J.; Bougher, S. W.; Fesen, C. G.

    1992-01-01

    Modern models of thermospheric composition and temperature and of excitation and radiative transfer processes are used to simulate the O I 130-nm emission from Mars measured by the Mariner 9 ultraviolet spectrometer. This paper uses the Mars thermospheric general circulation model calculations (MTGCM) of Bougher et al. (1988) and the Monte Carlo partial frequency redistribution multiple scattering code of Meier and Lee (1982). It is found that the decline in atomic oxygen through the daylight hours predicted by the MTGCM cannot be reconciled with the excess afternoon brightness seen in the data. Oxygen concentrations inferred from the data show a positive gradient through the day, in agreement with the original analysis by Strickland et al. (1973). In addition, the data suggest that the oxygen abundance increases toward high southerly latitudes, in contrast with the MTGCM prediction of high values in the Northern Hemisphere. It appears that solar forcing alone cannot account for the observed characteristics of the Martian thermosphere and that wave and tidal effects may profoundly affect the structure, winds, and composition.

  17. Bedside calculation of hemodynamic parameters with a hand-held programmable calculator. Part I.: Choice of hemodynamic formulas.

    PubMed

    Laurent, M

    1980-01-01

    Currently used hemodynamic and oxygen transport formulas are reviewed in order to chose the shortest form compatible with an optimal clinical accuracy. Programming of hand held calculators with these selected equations spares steps available in the program memory. (Acta anaesth. belg., 1980, 31, 45-52).

  18. 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.

  19. Oxygen nonstoichiometry, defect structure and oxygen diffusion in the double perovskite GdBaCo2O6-δ.

    PubMed

    Tsvetkov, D S; Ananjev, M V; Eremin, V A; Zuev, A Yu; Kurumchin, E Kh

    2014-11-14

    Oxygen nonstoichiometry of GdBaCo2O6-δ was studied by means of the thermogravimetric technique in the temperature range 600-1000 °C. The defect structure model based on the simple cubic perovskite GdCoO3-δ was shown to be valid for GdBaCo2O6-δ up to temperatures as low as 600 °C. Two independent methods, namely dc-polarization with the YSZ microelectrode and (18)O-isotope exchange with gas phase analysis, were used to determine the oxygen self-diffusion coefficient in the double perovskite GdBaCo2O6-δ. All measurements were carried out using ceramic samples identically prepared from the same single phase powder of GdBaCo2O6-δ. The experimental data on oxygen nonstoichiometry of GdBaCo2O6-δ allowed a precise calculation of the oxygen interphase exchange rate and the oxygen tracer diffusion coefficient on the basis of the isotope exchange measurements. The values of the oxygen self-diffusion coefficient measured by the dc-polarization technique were found to be in very good agreement with the ones of the oxygen tracer diffusion coefficient.

  20. Velocity Based Modulus Calculations

    NASA Astrophysics Data System (ADS)

    Dickson, W. C.

    2007-12-01

    A new set of equations are derived for the modulus of elasticity E and the bulk modulus K which are dependent only upon the seismic wave propagation velocities Vp, Vs and the density ρ. The three elastic moduli, E (Young's modulus), the shear modulus μ (Lamé's second parameter) and the bulk modulus K are found to be simple functions of the density and wave propagation velocities within the material. The shear and elastic moduli are found to equal the density of the material multiplied by the square of their respective wave propagation-velocities. The bulk modulus may be calculated from the elastic modulus using Poisson's ratio. These equations and resultant values are consistent with published literature and values in both magnitude and dimension (N/m2) and are applicable to the solid, liquid and gaseous phases. A 3D modulus of elasticity model for the Parkfield segment of the San Andreas Fault is presented using data from the wavespeed model of Thurber et al. [2006]. A sharp modulus gradient is observed across the fault at seismic depths, confirming that "variation in material properties play a key role in fault segmentation and deformation style" [Eberhart-Phillips et al., 1993] [EPM93]. The three elastic moduli E, μ and K may now be calculated directly from seismic pressure and shear wave propagation velocities. These velocities may be determined using conventional seismic reflection, refraction or transmission data and techniques. These velocities may be used in turn to estimate the density. This allows velocity based modulus calculations to be used as a tool for geophysical analysis, modeling, engineering and prospecting.