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. Microprobe and oxygen fugacity study of armalcolite

    NASA Technical Reports Server (NTRS)

    Friel, J. J.

    1976-01-01

    The stability of synthetic armalcolite was determined as a function of oxygen fugacity with particular regard to the oxidation state of iron and titanium. The equilibrium pseudobrookite (armalcolite) composition was measured at 1200 C under various conditions of oxidation typical of the lunar environment. These data, when compared with published descriptions of mare basalts, provide information about the conditions of crystallization of armalcolite-bearing lunar rocks. Some information about the crystal chemistry of armalcolite was obtained from X-ray diffraction and electron microprobe analyses of synthetic armalcolite and Zr-armalcolite. Further data were gathered from a comparison of the Mossbauer spectra of a phase pure stoichiometric armalcolite and one containing appreciable amounts of trivalent titanium.

  3. Crystallization temperatures and oxygen fugacities of magmas from the Southeast Indian Ocean Ridge system

    E-print Network

    Ongley, Lois Kathe

    1977-01-01

    College Chairman of Advisory Committee: Dr. Robert B. Scott Basalts from the Southeast Indian Ridge (SEIR) crystallized un- der abnormal conditions of low temperature, and high oxygen fugacity, Plagioclase-glass geothermometry was used to calculate... 36 Crystallization Temperatures Oxygen Fugacity Glass Chemistry 39 39 Summary of Salient Deductions. . . Regional Significance Conclusions References Cited . Appendix I 45 49 51 55 Vita 70 LIST OF TABLES Table 1: Petrographic summary...

  4. The color of meteoritic hibonite - an indicator of oxygen fugacity

    NASA Astrophysics Data System (ADS)

    Ihinger, P. D.; Stolper, E.

    1986-05-01

    Hibonites similar in composition to those found in Ca-Al-rich inclusions change color from blue, to green, to orange, to nearly colorless as oxygen fugacity is increased at high temperature from below the iron-wustite buffer up to air. The development of the blue color is correlated with the growth of an absorption band at 715 nm in the optical spectra of the hibonites as the oxygen fugacity is reduced. The growth of this band is attributed to the increasing concentration of Ti(3+) in these hibonites with decreasing oxygen fugacity. The blue hibonites in meteorites reflect equilibration under reducing conditions based on the intensity of 715 nm band, it is estimated that the hibonite in the Blue Angel inclusion indicates an oxygen fugacity four to five orders of magnitude more oxidizing than that expected in the early solar nebula. This may be due to formation in an anomalously oxidizing region of the nebula or to oxidation during cooling or later alteration. The orange hibonites in Allende reflect oxygen fugacities approximately ten or more orders of magnitude more oxidizing than the expected primitive nebula; this color probably indicates alteration of initially more reduced (blue?) hibonites. The colorless hibonite in the HAL inclusion reflects highly oxidizing conditions and/or its low Ti content.

  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. Dependence of dislocation creep of dunite on oxygen fugacity: Implications for viscosity variations in Earth's mantle

    Microsoft Academic Search

    J. W. Keefner; S. J. Mackwell; D. L. Kohlstedt; F. Heidelbach

    2011-01-01

    Fit to experimental data indicate an oxygen fugacity exponent m = 0.20 +\\/– 0.01Earlier work did not include the effects of oxygen fugacity on creepIn the mantle, increasing oxygen fugacity results in a 5x decrease in viscosity

  7. Martian Basalt Oxygen Fugacity and Geochemistry: Implications for a Heterogeneous Martian Mantle

    NASA Astrophysics Data System (ADS)

    Herd, C. D. K.

    2002-01-01

    The oxygen fugacity (fO2) of the martian basalts (a.k.a. basaltic shergottites) has recently been recognized as important in understanding their petrogeneses. The correlation between oxygen fugacity and certain geochemical parameters (initial Sr and Nd isotopic compositions, La/Yb ratios) indicates the presence of long-term incompatible-element enriched and depleted reservoirs, which are oxidized and reduced, respectively. Oxygen fugacity variations in the martian basalts have been modeled based on assimilation of oxidized crustal ("crust-like") material by reduced, mantle-derived magmas. However, there remains the possibility that the oxygen fugacity of the martian basalts is controlled by the nature of their source regions. Here I review existing oxygen fugacity data for the martian meteorites, present some speculative estimates for newer martian basalts, and explore the heterogeneous mantle model in more detail.

  8. 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.

  9. Oxygen fugacity control in piston-cylinder experiments: a re-evaluation

    NASA Astrophysics Data System (ADS)

    Jakobsson, Sigurdur; Blundy, Jon; Moore, Gordon

    2014-06-01

    Jakobsson (Contrib Miner Petrol 164(3):397-407, 2012) investigated a double capsule assembly for use in piston-cylinder experiments that would allow hydrous, high-temperature, and high-pressure experiments to be conducted under controlled oxygen fugacity conditions. Using a platinum outer capsule containing a metal oxide oxygen buffer (Ni-NiO or Co-CoO) and H2O, with an inner gold-palladium capsule containing hydrous melt, this study was able to compare the oxygen fugacity imposed by the outer capsule oxygen buffer with an oxygen fugacity estimated by the AuPdFe ternary system calibrated by Barr and Grove (Contrib Miner Petrol 160(5):631-643, 2010). H2O loss or gain, as well as iron loss to the capsule walls and carbon contamination, is often observed in piston-cylinder experiments and often go unexplained. Only a few have attempted to actually quantify various aspects of these changes (Brooker et al. in Am Miner 83(9-10):985-994, 1998; Truckenbrodt and Johannes in Am Miner 84:1333-1335, 1999). It was one of the goals of Jakobsson (Contrib Miner Petrol 164(3):397-407, 2012) to address these issues by using and testing the AuPdFe solution model of Barr and Grove (Contrib Miner Petrol 160(5):631-643, 2010), as well as to constrain the oxygen fugacity of the inner capsule. The oxygen fugacities of the analyzed melts were assumed to be equal to those of the solid Ni-NiO and Co-CoO buffers, which is incorrect since the melts are all undersaturated in H2O and the oxygen fugacities should therefore be lower than that of the buffer by 2 log.

  10. 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.

  11. The effect of the oxygen fugacity on carbon speciation in the Earth’s mantle

    NASA Astrophysics Data System (ADS)

    Stagno, V.; Frost, D. J.; McCammon, C. A.

    2009-12-01

    The mantle is the largest identified reservoir for carbon on Earth, but the residence time of carbon in the mantle and its release depends crucially on the conditions under which it is stable within melts or fluids, compared with conditions under which it forms solid phases. At a given pressure and temperature the stability of carbonate- bearing minerals and melts (carbonatites and kimberlites) relative to graphite/diamond depends on the oxygen fugacity. In this study, the oxygen fugacities buffered by equilibria involving both elemental carbon (graphite or diamond) and carbonate (minerals or melts) were determined in simplified Fe-Ca-Mg-Si-O-C model peridotite at pressures between 2.5 and 25 GPa and temperatures at and above the carbonated peridotite solidus (1100-1600°C). Oxygen fugacities were measured using an Ir-Fe alloy as a sliding redox sensor. The results show that as the carbonate peridotite solidus is crossed at various pressures, the increasing SiO2 content of the melt with temperature decreases the activity of the carbonate component which, in turn, drives the equilibrium oxygen fugacity down compared to the extrapolation of carbon/carbonate equilibrium from previous studies. There is evidence from mantle xenoliths that the effect of pressure on ferric/ferrous equilibria involving major mantle minerals drives the oxygen fugacity down with increasing depth. In order to infer the carbon speciation with depth, we compare our measurements of the oxygen fugacity of carbon/carbonate equilibria with the expected oxygen fugacity of the mantle. Beneath mid-ocean ridges, the relative oxygen fugacity of peridotitic rocks should increase with decreasing depth. In this scenario it is possible that diamond and graphite are stable at depth, but become oxidized as a result of decompression on the ferric/ferrous equilibria of a garnet peridotite along the adiabat. Only once graphite or diamonds are oxidized can the resulting carbonate produce small degree carbonate-rich melts with dramatic implications for the trace element signature and physical properties of erupted MORBs. In addition, we performed experiments in Fe-Ca-Mg-Al-Si-O-C system to determine the Fe3+ content of garnet at an oxygen fugacity buffered by the carbon-carbonate equilibria. The ferric iron contents of the garnet in the run products were determined by 57Mössbauer spectroscopy. The results from these experiments allow the redox conditions for carbon and carbonate stability to be compared directly to the Fe3+/Fetot ratio on mantle rocks. Our results imply that: (1) most of the upper mantle and transition zone are in the diamond stability field and carbonates can melt in a fertile peridotite only at depths less than 100 km. Melting at greater depths likely occurs in mantle that is more oxidised (i.e. contains more Fe3+) than the most oxidised garnet peridotite samples; (2) measurements of Fe3+/Fetot ratios of garnets in equilibrium with graphite and carbonate are slightly inconsistent with the predictions of previously published oxythermobarometers; (3) the effect of pressure on the carbonate/carbon buffer indicates that the diamond stability field may not persist deep into the lower mantle with carbonates being the stable host of carbon.

  12. High Pressure Effects on the Iron-Iron Oxide and Nickel-Nickel Oxide Oxygen Fugacity Buffers

    E-print Network

    Campbell, Andrew

    High Pressure Effects on the Iron-Iron Oxide and Nickel- Nickel Oxide Oxygen Fugacity Buffers interpretation of high pressure experiments, specifically Fe-Ni exchange between metallic and oxide phases fugacity (fO2) buffer. These buffers are precisely known at 1 bar, but under high pressures corresponding

  13. Potassic volcanism near Mono basin, California: Evidence for high water and oxygen fugacities inherited from subduction

    Microsoft Academic Search

    Rebecca A. Lange; Ian S. E. Carmichael; Paul R. Renne

    1993-01-01

    Exposed around the margins of Mono basin and the periphery of Long Valley caldera are ˜100 km3 of potassic, basic to intermediate lavas that record high water and oxygen fugacities. Most eruptions occurred between 4 and 2 Ma, although sporadic potassic volcanism continued into the Quaternary with a pulse between 0.1 and 0.5 Ma, ˜15 km northeast of Mono basin.

  14. 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.

  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 Astrophysics Data System (ADS)

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

    1993-09-01

    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. 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.

  17. Potassic volcanism near Mono basin, California: Evidence for high water and oxygen fugacities inherited from subduction

    NASA Astrophysics Data System (ADS)

    Lange, Rebecca A.; Carmichael, Ian S. E.; Renne, Paul R.

    1993-10-01

    Exposed around the margins of Mono basin and the periphery of Long Valley caldera are ˜100 km3 of potassic, basic to intermediate lavas that record high water and oxygen fugacities. Most eruptions occurred between 4 and 2 Ma, although sporadic potassic volcanism continued into the Quaternary with a pulse between 0.1 and 0.5 Ma, ˜15 km northeast of Mono basin. The lava types include absarokite, minette, hornblende lamprophyre, trachybasalt, and trachyandesite. Estimated water contents for lavas without hydrous phenocrysts range between 2 and 3 wt% considerably more than mid-ocean ridge, oceanic island, or back-arc magmas. Calculated fO2, values fall between -0.4 and +1.2 log units of the Ni-NiO buffer. Although this potassic suite was erupted in an extensional tectonic setting at the western margin of the Basin and Range province, its high K2O/TiO2 and low Zr/Ba ratios suggest a subduction-modified mantle source. If subduction was the process that enriched the lithospheric mantle in large-ion lithophile elements (K, Ba, etc.), it was also a mechanism for mantle oxidation and hydration.

  18. 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. (Jacobs Engineering); (NASA JSC); (Hamilton Sundstrand); (UC)

    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.

  19. 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.

  20. Metal-silicate partitioning and constraints on core composition and oxygen fugacity during Earth accretion

    NASA Astrophysics Data System (ADS)

    Corgne, Alexandre; Keshav, Shantanu; Wood, Bernard J.; McDonough, William F.; Fei, Yingwei

    2008-01-01

    We present the results of new partitioning experiments between metal and silicate melts for a series of elements normally regarded as refractory lithophile and moderately siderophile and volatile. These include Si, Ti, Ni, Cr, Mn, Ga, Nb, Ta, Cu and Zn. Our new data obtained at 3.6 and 7.7 GPa and between 2123 and 2473 K are combined with literature data to parameterize the individual effects of oxygen fugacity, temperature, pressure and composition on partitioning. We find that Ni, Cu and Zn become less siderophile with increasing temperature. In contrast, Mn, Cr, Si, Ta, Nb, Ga and Ti become more siderophile with increasing temperature, with the highly charged cations (Nb, Ta, Si and Ti) being the most sensitive to variations of temperature. We also find that Ni, Cr, Nb, Ta and Ga become less siderophile with increasing pressure, while Mn becomes more siderophile with increasing pressure. Pressure effects on the partitioning of Si, Ti, Cu and Zn appear to be negligible, as are the effects of silicate melt composition on the partitioning of divalent cations. From the derived parameterization, we predict that the silicate Earth abundances of the elements mentioned above are best explained if core formation in a magma ocean took place under increasing conditions of oxygen fugacity, starting from moderately reduced conditions and finishing at the current mantle-core equilibrium value.

  1. The dependence of the partitioning of iron and europium between plagioclase and hydrous tonalitic melt on oxygen fugacity

    Microsoft Academic Search

    Max Wilke; Harald Behrens

    1999-01-01

    The dependence of iron and europium partitioning between plagioclase and melt on oxygen fugacity was studied in the system\\u000a SiO2(Qz)—NaAlSi3O8(Ab)—CaAl2Si2O8(An)—H2O. Experiments were performed at 500?MPa and 850?°C\\/750?°C under water saturated conditions. The oxygen fugacity was varied\\u000a in the log f\\u000a O2-range from ?7.27 to ?15.78. To work at the most reducing conditions the classical double-capsule technique was modified.\\u000a The sample

  2. 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 address all of these questions.

  3. 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+/?Fe 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 are very few analyses of garnet Fe3+/?Fe ratios from eclogite samples, the range in fO2 recorded by available eclogitic xenoliths is similar to that reported for peridotitic xenoliths and generally within the graphite/diamond stability field. Estimates for the average bulk Fe3+/?Fe ratio of modern basaltic oceanic crust, however, are higher than the values for most of these xenoliths, and upon subduction, crustal carbon is likely to remain in the carbonate stability field to depths of at least 250 km. If eclogite xenoliths originated from subducted oceanic crust, then their generally lower fO2 most likely reflects either lower initial basaltic Fe3+/?Fe ratios, loss of Fe2O3 through partial melting or the initial presence of organic carbon.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    We investigate the relationship between sulfur and oxygen fugacity at Erta Ale and Masaya volcanoes. Oxygen fugacity was assessed utilizing Fe3+/?Fe and major element compositions measured in olivine-hosted melt inclusions and matrix glasses. Erta Ale melts have Fe3+/?Fe of 0.15-0.16, reflecting fO2 of ?QFM 0.0 ± 0.3, which is indistinguishable from fO2 calculated from CO2/CO ratios in high-temperature gases. Masaya is more oxidized at ?QFM +1.7 ± 0.4, typical of arc settings. Sulfur isotope compositions of gases and scoria at Erta Ale (?34Sgas - 0.5‰; ?34Sscoria + 0.9‰) and Masaya (?34Sgas + 4.8‰; ?34Sscoria + 7.4‰) reflect distinct sulfur sources, as well as isotopic fractionation during degassing (equilibrium and kinetic fractionation effects). Sulfur speciation in melts plays an important role in isotope fractionation during degassing and S6+/?S is <0.07 in Erta Ale melt inclusions compared to >0.67 in Masaya melt inclusions. No change is observed in Fe3+/?Fe or S6+/?S with extent of S degassing at Erta Ale, indicating negligible effect on fO2, and further suggesting that H2S is the dominant gas species exsolved from the S2--rich melt (i.e., no redistribution of electrons). High SO2/H2S observed in Erta Ale gas emissions is due to gas re-equilibration at low pressure and fixed fO2. Sulfur budget considerations indicate that the majority of S injected into the systems is emitted as gas, which is therefore representative of the magmatic S isotope composition. The composition of the Masaya gas plume (+4.8‰) cannot be explained by fractionation effects but rather reflects recycling of high ?34S oxidized sulfur through the subduction zone.

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    Measurements of the oxygen fugacity, f(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(O2)-T relationship of the iron-wustite assemblage and 1.2 log atm units above iron-wustite. Interpretation of the data indicates that, throughout most of the cooling history of the meteorite, f(O2) values were defined by equilibria involving iron-bearing species at values close to the f(O2) of the assemblage iron-wustite. Measured f(O2) data are compatible with crystallization and cooling at pressures greater than 50 bars.

  6. 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.

  7. melt is independent of oxygen fugacity, since the oxidation state of carbon in both coexisting phases is the same.

    E-print Network

    Nedimoviæ, Mladen R.

    of the global carbon cycle. If traces of carbon were stored as a solid solution in olivine, releasing large. Carbon geodynamic cycle. Nature 300, 171­173 (1982). 2. Jambon, A. Earth degassing and largemelt is independent of oxygen fugacity, since the oxidation state of carbon in both coexisting

  8. 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 ?-XANES determination of Fe3+/Fe? 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+/Fe? 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 ?51V 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 ?51V of the arc lavas of almost 0.8‰, which co-varies with SiO2, CaO, and V/Sc ratios. Co-variation of ?51V 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 ?51V inter-suite variability in arc lavas versus the ?51V signature of MORB. [1] Lee, C.T.A., Leeman, W.P., Canil, D., Li, Z.X.A. 2005. J. Pet. 46, 2313-2336. [2] Kelley, K.A., Cottrell, E. 2009. Science, 325, 605-607. [3] Nielsen S.G., Prytulak J., Halliday A.N. 2010. Geost. Geoanal. Res., accepted. [4] Prytulak J., Nielsen S.G., Halliday A.N. 2010. Geost. Geoanal. Res., accepted. [5] Elliott,T., Plank, T., Zindler, A., White, W., Bourdon, B. 1997. J. Geophys. Res. 102, 14991-15019. [6] Kelley, K.A., Plank, T., Ludden, J., Staudigel, H. 2003. Geochem. Geophys. Geosyst. 4, doi: 10.1029/2002GC000435.

  9. Vanadium and niobium behavior in rutile as a function of oxygen fugacity: evidence from natural samples

    NASA Astrophysics Data System (ADS)

    Liu, Lei; Xiao, Yilin; Aulbach, Sonja; Li, Dongyong; Hou, Zhenhui

    2014-06-01

    Vanadium occurs in multiple valence states in nature, whereas Nb is exclusively pentavalent. Both are compatible in rutile, but the relationship of V-Nb partitioning and dependence on oxygen fugacity (expressed as fO2) has not yet been systematically investigated. We acquired trace-element concentrations on rutile grains ( n = 86) in nine eclogitic samples from the Dabie-Sulu orogenic belt by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and combined them with published results in order to assess the direct and indirect effects of oxygen fugacity on the partitioning of V and Nb into rutile. A well-defined negative correlation between Nb (7-1,200 ppm) and V concentrations (50-3,200 ppm) was found, documenting a competitive relationship in the rutile crystal that does not appear to be controlled by bulk rock or mineral compositions. Based on the published relationship of RtDV and V valence with ?QFM, we suggest that the priority order of V incorporation into rutile is V4+ > V3+ > V5+. The inferred Nb-V competitive relationship in rutile from the Dabie-Sulu orogenic belt could be explained by decreasing fO2 due to dehydration reactions involving loss of oxidizing fluids during continental subduction: The increased proportion of V3+ (expressed as V3+/?V) and attendant decrease in RtDV is suggested to lead to an increase in rutile lattice sites available for Nb5+. A similar effect may be observed under more oxidizing conditions. When V5+/?V increases, RtDV shows a dramatic decline and Nb concentration increases considerably. This is possibly documented by rutile in highly metasomatized and oxidized MARID-type (MARID: mica-amphibole-rutile-ilmenite-diopside) mantle xenoliths from the Kaapvaal craton, which also show a negative V-Nb covariation. In addition, their Nb/Ta covaries with V concentrations: For V concentrations <1,250 ppm, Nb/Ta ranges between 35 and 45, whereas for V > 1,250 ppm, Nb/Ta is considerably lower (5-15). This relationship is mainly controlled by a change in Nb concentrations, suggesting that the indirect dependence of RtDNb on fO2, which is not mirrored in RtDTa, can exert considerable influence on rutile Nb-Ta fractionation.

  10. 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.

  11. Oxygen Fugacity Recorded Pigeonite: Indications of a Heterogeneous Martian Magma Source Region?

    NASA Astrophysics Data System (ADS)

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

    2002-01-01

    Oxygen fugacity (fO2) is a key physical parameter which influences the crystallization sequences of magmas, as well as the composition of the resulting minerals. On a planet-wide basis, the distribution of elements between the metallic core and the silicate portion of the planet is influenced by the fO2 at the time of differentiation. Additionally, if the intrinsic fO2 of a planet is known, the processes which may change that value can be investigated. Although magmatic fO2 can reflect the degree of oxidation of the magma source region, it can also provide insight into processes, such as metasomatism, degassing, or assimilation, which may have operated on and in the magma as it moved to the surface. Recent work on the basaltic shergottites has provided new measurements of the fO2 recorded in the pyroxenes of these meteorites. These pyroxenes exhibit an fO2 range of approximately 3-4 orders of magnitude. Several processes have been proposed to explain the origin of these differences, the majority of which rely on assimilation. New data, however, is consistent with intrinsic fO2 differences in the magma source region being responsible for the measured SNC fO2 variations. More detailed analyses of natural SNC pyroxenes are needed in order to better understand the source of the fO2 range recorded in the basaltic shergottites.

  12. A furnace design for XANES spectroscopy of silicate melts under controlled oxygen fugacities and temperatures to 1773 K.

    PubMed

    Berry, Andrew J; Shelley, J Michael G; Foran, Garry J; O'Neill, Hugh St C; Scott, Dean R

    2003-07-01

    A controlled-atmosphere furnace has been constructed for X-ray absorption spectroscopy experiments under imposed oxygen fugacities at temperatures up to 1773 K. The use of the furnace is demonstrated in a study of the oxidation state of Cr in a basaltic silicate melt (mid-ocean ridge basalt) by K-edge XANES spectroscopy. This is the first time the Cr(2+)/Cr(3+) ratio has been identified directly in an Fe-bearing melt. At typical terrestrial oxygen fugacities around half the Cr is present as Cr(2+), even though this oxidation state has never been identified in a terrestrial material and only Cr(3+) is observed after quenching to a glass. Cr(2+) oxidizes to Cr(3+) on cooling in the presence of Fe(3+) according to the electron exchange reaction Cr(2+) + Fe(3+) --> Cr(3+) + Fe(2+). This illustrates the importance of the in situ determination of metal oxidation states in melts. PMID:12824934

  13. Solubility of CO 2 in a Ca-rich leucitite: effects of pressure, temperature, and oxygen fugacity

    Microsoft Academic Search

    Yves Thibault; John R. Holloway

    1994-01-01

    The solubility of carbon dioxide in a Ca-rich leucitite has been investigated as a function of pressure (0.1–2.0 GPa), temperature (1200–1600°C), and oxygen fugacity. The experiments were done in a rapid-quench internally-heated pressure vessel (0.1 GPa) and a piston cylinder (0.5–2.0 GPa). The leucitite glass, previously equilibrated at NNO, and silver oxalate were loaded in Fe-doped Pt capsules (oxidized conditions)

  14. 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.

  15. Carbonate and Magnetite Parageneses as Monitors of Carbon Dioxide and Oxygen Fugacity

    NASA Technical Reports Server (NTRS)

    Koziol, Andrea M.

    2000-01-01

    The stable coexistence of siderite with other key minerals, such as graphite or magnetite, is only possible under certain restrictive conditions of CO2 and O2 fugacity. Carbonate parageneses in Mars meteorite ALH 84001 are analyzed.

  16. 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.

  17. 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/?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, 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 determined by XANES at beamline 13-IDC of the Advanced Photon Source at Argonne National Laboratory. The D/H ratios of the melt inclusions from our hydration experiments range from 18.4-25.6, as compared to ~1.448 x 10-4 for mantle-derived basalt, indicating significant addition of deuterium. The 18O/17O ratios of melt inclusions are within uncertainty of natural ratios for mantle-derived materials. The H2O content of individual melt inclusions increased by as much as 3.9 wt %, while the oxidation state of Fe in the hydrated melt inclusions is not significantly different from the starting materials. The concentration of H2O in melt inclusions from the dehydration experiments ranges from 2.8 to 0.05 wt%, and dehydration is nearly complete after 18 hours. The ?D value of the melt inclusions increases significantly as dehydration progresses and is consistent with a calculated diffusive fractionation of hydrogen isotopes. Neither diffusive fractionation of H2O nor equilibrium fractionation via vapor loss is consistent with the isotopic enrichment observed in dehydrated melt inclusions. The oxidation state of Fe ranges from Fe3+/?Fe = 0.58±0.04 (NiNiO+4) for the starting materials to Fe3+/?Fe = 0.21±0.03 (NiNiO+0.6) for melt inclusions that were heated for 18 hours, and re-equilibrates on the same timescale as H2O. References: [1] K.A. Kelley, E. Cottrell, Science 325, 605 (2009); [2] A. V. Sobolev, L. V. Danyushevsky, J Petrol 35, 1183 (1994); [3] L. V. Danyushevsky, A. W. McNeill, A. V. Sobolev, Chem Geol 183, 5 (2002).

  18. 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}.

  19. 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 comparable to proton diffusion. Our numerical model is the first to incorporate this point-defect mediated re-equilibration mechanism. Furthermore, the ability to model not only water contents, but also the oxygen fugacity and multiple volatile species is a powerful tool to assess the degree, temperature, and duration of diffusive re-equilibration that a melt inclusion has undergone and the integrity of its composition in yielding estimates of pre-eruptive volatile contents.

  20. Single grain estimations of oxygen fugacity in subcratonic mantle lithosphere using compositions of Ilmenite, Chromite , Garnet and Pyroxenes.

    NASA Astrophysics Data System (ADS)

    Ashchepkov, I.

    2012-04-01

    Calculated oxygen fugacity conditions for ilmenites and chromites were obtained using the monomineral version of the Taylor (1998) oxygen barometers with the calculation of Fe#Ol according to (Ashchepkov et al., 2010). The monomineral version of the Gar- Ol- Opx method (Gudmundsson & Wood, 1995) was obtained using the regression between FO2 and Fe3 in garnet and additional correlation to P and T. F5=Fe#Gar/FeGar; Fo2= 2030.2*Ff5**3-1061.4*F5**2+190.89*F5-12.644 Fo2 = (Fo2-0.01*P (kbar)+(ToC-500)/(3500 -05.)*0.9 The obtained values wee regression and the new Cpx method constructed by the cross correlations of the Fe3+ in Cpx with the oxygen fugacity values obtained for garnets were used for the additional characterization of the mantle SCLM section. The statistical between regression obtained from the work (Gudmundsson, Wood , 1995) and corrections for the temperature and pressure justified by the comparisons obtained with the Ol- Sp and Ilm- Ol oxybarometers (Taylor et al., 1998) allow to estimate the FO2 (? log QMF) by following simple equations: For clinopyroxene the cross calibration allow to receive the following regression. Fo2=-186.71*Fe3**2+48.617*Fe3 - 2.3262; Fo2 = Fo2+(T0-500)/3500-0.01*P Fo2 = (Fo2-0.01*P (kbar)+(ToC-500)/3500 -05.)*0.7 For clinopyroxene the cross calibration allow to receive the following regression. Fo2=-186.71*Fe3**2+48.617*Fe3 - 2.3262; Fo2 = Fo2+(T0-500)/3500-0.01*P Fo2=(Fo2-0.5)*0.8 For the orthopyroxene the correlating with the CPx parameter was calculated as following The Fe3'Opx was corrected as Fe3Opx-0.03;Fo2=23.882*Fe3'Opx*(Fe1*15)**2-1.8805 Fo2= Fo2+((T0-400)/1000)*(Fe1*20)-0.0175*P; Fo2=(Fo2*(Fe1*15)**2-0.9*P/70)*0.9 Fo2=(Fo2-0.5)*0.9 Despite on the rather low resolution of the Fe3+ EPMA estimates statistically the determined parameters are rather useful and mark major levels in the SCLM beneath Siberian and other cratons. The rise of FO2 is marked in the three major intervals - in the lithosphere base near the base of lithosphere marking cumulates and shearing peridotites. Near the boundary of the upper and lower mantle at 40 kbar marking so called pyroxenite layer and within basaltic trap - cresponding to the level of water bearing malt interaction , Despite there several layer corresponding to the mantle layering and levels of polybaric hydraulic shearing coused by the protokimberlite melt intrusion. The garnets commonly give some additional trends of joined rising of Fo2 and decreasing of the pressures. There amount in the lower part of the mantle columns is reaching 5-6 units. They are very often correlating with the values determined for the Cpx but later are generally more oxidized. The diamond bearing associations including eclogites are commonly less oxidized belonging to the diamond stability field found by (McCammon et al ., 2001) . Sometimes these values are as low as -5.5 log u. ? log QMF. Interesting feature the upper part of the SCLM is sometimes less oxidized then pyroxenite lens and even lower part of SCLM. The trends of the ilmenites commonly are just marking the line of diamong stability in DSCLM od became higher and (even SCLM) in the upper part . The Ti- bearing spinel are commonly marking slightly lower values then ilmenites while Ti-less chromites are commonly less oxidized marking major units in mantle layering. RBRF grant 11-05-00060.

  1. Theoretical phase relations involving cordierite and garnet revisited: the influence of oxygen fugacity on the stability of sapphirine and spinel in the system Mg-Fe-Al-Si-O

    Microsoft Academic Search

    B. J. Hensen

    1986-01-01

    The theoreticalP-T grid for stability relations of the phases cordierite (Cd), sapphirine (Sa), hypersthene (Hy), garnet (Ga), spinel (Sp), sillimanite (Si), and quartz (Qz) of Hensen (1971), has proved useful in the interpretation of metamorphic mineral assemblages formed at low oxygen fugacity. Both experimental data and evidence from natural rocks indicate that at high oxygen fugacity compatability relations change as

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Fe–Mg diffusion in olivine I: experimental determination between 700 and 1,200 ° C as a function of composition, crystal orientation and oxygen fugacity

    Microsoft Academic Search

    Ralf Dohmen; Hans-Werner Becker; Sumit Chakraborty

    2007-01-01

    We have determined Fe–Mg diffusion coefficients in olivines from different sources (Nanga Parbat, Pakistan and San Carlos,\\u000a Arizona, USA) at atmospheric pressure as a function of composition, oxygen fugacity (10?5–10?12 Pa) and temperature (700–1200°C) using thin films produced by pulsed laser deposition and RBS to analyze the concentration\\u000a profiles. We have characterized the nano-scale structure and composition of the thin films

  7. 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 physical and chemical properties of the lower mantle, new measurements are planned to increase the data set on ferropericlase inclusions. Moreover, a multi disciplinary study involving cathodoluminescence studies combined to isotopic and optical studies is suggested for further work.

  8. Experimental study of trace element partitioning between enstatite and melt in enstatite chondrites at low oxygen fugacities and 5 GPa

    NASA Astrophysics Data System (ADS)

    Cartier, Camille; Hammouda, Tahar; Doucelance, Régis; Boyet, Maud; Devidal, Jean-Luc; Moine, Bertrand

    2014-04-01

    In order to investigate the influence of very reducing conditions, we report enstatite-melt trace element partition coefficients (D) obtained on enstatite chondrite material at 5 GPa and under oxygen fugacities (fO2) ranging between 0.8 and 8.2 log units below the iron-wustite (IW) buffer. Experiments were conducted in a multianvil apparatus between 1580 and 1850 °C, using doped (Sc, V, REE, HFSE, U, Th) starting materials. We used a two-site lattice strain model and a Monte-Carlo-type approach to model experimentally determined partition coefficient data. The model can fit our partitioning data, i.e. trace elements repartition in enstatite, which provides evidence for the attainment of equilibrium in our experiments. The precision on the lattice strain model parameters obtained from modelling does not enable determination of the influence of intensive parameters on crystal chemical partitioning, within our range of conditions (fO2, P, T, composition). We document the effect of variable oxygen fugacity on the partitioning of multivalent elements. Cr and V, which are trivalent in the pyroxene at around IW - 1 are reduced to 2+ state with increasingly reducing conditions, thus affecting their partition coefficients. In our range of redox conditions Ti is always present as a mixture between 4+ and 3+ states. However the Ti3+-Ti4+ ratio increases strongly with increasingly reducing conditions. Moreover in highly reducing conditions, Nb and Ta, that usually are pentavalent in magmatic systems, appear to be reduced to lower valence species, which may be Nb2+ and Ta3+. We propose a new proxy for fO2 based on D(Cr)/D(V). Our new data extend the redox range covered by previous studies and allows this proxy to be used in the whole range of redox conditions of the solar system objects. We selected trace-element literature data of six chondrules on the criterion of their equilibrium. Applying the proxy to opx-matrix systems, we estimated that three type I chondrules have equilibrated at IW - 7 ± 1, one type I chondrule at IW - 4 ± 1, and two type II chondrules at IW + 3 ± 1. This first accurate estimation of enstatite-melt fO2 for type I chondrules is very close to CAI values. Find the best-fit for trivalent elements. We set the r0M1 (3+) range to 0.55-0.75 Å, based on visual observations of the datapoints. For the other variables we have set boundary values beyond which the solutions would be unacceptable. For example, r0M2 (3+) has to be larger than r0M1 (3+). Finally we restricted the D0 range as follow: 0.2 r0(3+) > r0(4+) (see van Westrenen et al., 2000, for explanation), together with visual observation of our experimental data. D0 ranges: 1 < D0M1(2+) < 100; D0M2 (3+) < D0M2(2+) < 100 ; 0.01 < D0M1(4+) < 0.1 ; 0.0001 < D0M2(4+) < 0.01. These ranges are based on visual observation of our experimental data.

  9. 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+/? 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+/? 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 noteworthy that a variation of oxygen fugacity was registered in multiple inclusions extracted from the same host diamonds. However, because the inclusions were removed from the host without textural control, information on the direction of any redox gradient that may have evolved, and possible correlation with diamond growth or anomalies in the variation of the redox conditions through time, were lost. These observations combined with the geographical correlation observed among all inclusions measured in the present work and from previous studies 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 such oxygen fugacities may affect the physical and chemical properties of the lower mantle, new measurements are planned to increase the data set on ferropericlase inclusions. Moreover, a multi disciplinary study involving cathodoluminescence studies and isotopic and optical studies is suggested for further work. References Frost et al. (2004) Nature, 428, 409-412. Longo et al., In preparation McCammon et al. (2004) Earth and Planetary Science Letters, 222, 423-434. McCammon et al. (1997) Science, 278, 434-436.

  10. The effect of chemical composition and oxygen fugacity on the electrical conductivity of dry and hydrous garnet at high temperatures and pressures

    NASA Astrophysics Data System (ADS)

    Dai, Lidong; Li, Heping; Hu, Haiying; Shan, Shuangming; Jiang, Jianjun; Hui, Keshi

    2012-04-01

    The in situ electrical conductivity of hydrous garnet samples (Py20Alm76Grs4-Py73Alm14Grs13) was determined at pressures of 1.0-4.0 GPa and temperatures of 873-1273 K in the YJ-3000t apparatus using a Solartron-1260 impedance/gain-phase analyzer for various chemical compositions and oxygen fugacities. The oxygen fugacity was controlled by five solid-state oxygen buffers (Fe2O3 + Fe3O4, Ni + NiO, Fe + Fe3O4, Fe + FeO, and Mo + MoO2). Experimental results indicate that within a frequency range from 10-2 to 106 Hz, electrical conductivity is strongly dependent on signal frequency. Electrical conductivity shows an Arrhenius increase with temperature. At 2.0 GPa, the electrical conductivity of anhydrous garnet single crystals with various chemical compositions (Py20Alm76Grs4, Py30Alm67Grs3, Py56Alm43Grs1, and Py73Alm14Grs13) decreases with increasing pyrope component (Py). With increasing oxygen fugacity, the electrical conductivity of dry Py73Alm14Grs13 garnet single crystal shows an increase, whereas that of a hydrous sample with 465 ppm water shows a decrease, both following a power law (exponents of 0.061 and -0.071, respectively). With increasing pressure, the electrical conductivity of this hydrous garnet increases, along with the pre-exponential factors, and the activation energy and activation volume of hydrous samples are 0.7731 ± 0.0041 eV and -1.4 ± 0.15 cm3/mol, respectively. The results show that small hopping polarons left( {{text{Fe}}_{text{Mg}}^{ \\cdot } } right) and protons ( {text{H}}^{ \\cdot } ) are the dominant conduction mechanisms for dry and wet garnet single crystals, respectively. Based on these results and the effective medium theory, we established the electrical conductivity of an eclogite model with different mineral contents at high temperatures and high pressures, thereby providing constraints on the inversion of field magnetotelluric sounding results in future studies.

  11. 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 Cameca 1280 ion microprobe at WHOI. The oxidation state of Fe was determined by XANES at beamline 13-IDC of the Advanced Photon Source at Argonne National Laboratory. Results from our experiments confirm that the mechanism for loss or gain of H2O from olivine-hosted melt inclusions is lattice diffusion of protons, and that the concentration of H2O in melt inclusions changes rapidly. Re-equilibration of oxygen fugacity occurs via diffusion of point defects on timescales comparable to proton diffusion. Further, our results demonstrate that these processes are independent of one another, so that correlations between H2O concentration and the oxidation state of Fe in the melt do not result from diffusive re-equilibration. However, melt inclusions that initially had significantly different H2O and TiO2 contents can end up with a range of TiO2 at nearly constant H2O following loss or gain of protons. In this case, use of TiO2 as an indicator of extent of peridotite partial melting results in erroneous conclusions about the influence of H2O on peridotite partial melting. References: [1] Kelley, K. A. & Cottrell, E., Science 325, 605-607 (2009); [2] Kelley, K. A. et al., J Geophys Res 111 (2006); [3] Kelley, K. A. et al., J Petrol 51, 1711-1738 (2010).

  12. 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 a higher fO2 than the IW buffer at pressures lower than 40 GPa, and the magnitude of this difference decreases at higher pressures. This qualitatively indicates an increasingly lithophile character for W at higher pressures. The WWO buffer was quantitatively applied to W metal-silicate partitioning by using the WWO-IW buffer difference in combination with literature data on W metal-silicate partitioning to model the exchange coefficient (KD) for the Fe-W exchange reaction. This approach captures the pressure dependence of W metal-silicate partitioning using the WWO-IW buffer difference and models the activities of the components in the silicate and metallic phases using an expression of the Gibbs excess energy of mixing. Calculation of KD along a peridotite liquidus predicts a decrease in W siderophility at higher pressures that supports the qualitative behavior predicted by the WWO-IW buffer difference, and agrees with findings of others. Comparing the competing effects of temperature and pressure on W metal-silicate partitioning, our results indicate that pressure exerts a greater effect.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Effect of oxygen fugacity on the H 2O storage capacity of forsterite in the carbon-saturated systems

    NASA Astrophysics Data System (ADS)

    Sokol, Alexander G.; Palyanov, Yury N.; Kupriyanov, Igor N.; Litasov, Konstantin D.; Polovinka, Mariya P.

    2010-08-01

    High pressure experiments have been performed in the systems Mg 2SiO 4-C-O-H and Mg 2SiO 4-K 2CO 3-C at 6.3 GPa and 1200 to 1600 °C using a split-sphere multi-anvil apparatus. In the Mg 2SiO 4-C-O-H system the composition of fluid was modeled by adding different amounts of water and stearic acid. The fO 2 was controlled by the Mo-MoO 2 or Fe-FeO oxygen buffers. Several experiments in the Mg 2SiO 4-C-O-H system and all experiments in the Mg 2SiO 4-K 2CO 3-C system have been conducted without buffering the fO 2. Forsterite in the system Mg 2SiO 4-K 2CO 3-C does not reveal OH absorption bands in the IR spectra, while forsterite coexisting with carbon-bearing fluid and silicate melt at log fO 2 from FMQ-2 to FMQ-5 (from 2 to 5 log units below fayalite-magnetite-quartz oxygen buffer) contains 800-1850 wt. ppm H 2O. The maximum concentrations were detected at 1400 °C and FMQ-3.5. We observed an increase in the solidus temperature in the system Mg 2SiO 4-C-O-H from 1200 to above 1600 °C with log fO 2 decreasing from FMQ-2 to FMQ-5. The increase of the solidus temperature and the broadening of the stability field of the H 2O-H 2-CH 4 subsolidus fluid phase at 1400-1600 °C explain the high H 2O storage capacity of forsterite relative to that crystallized from carbon-free, oxidized, hydrous, silicic melt. At temperatures above 1400 °C liquidus forsterite precipitated along with diamond from oxidized (FMQ-1) carbonate-silicate melt and from silicate melt dissolving the moderately reduced C-O-H fluid (from FMQ-2 to FMQ-3.5). Formation of diamond was not detected under ultra-reduced conditions (FMQ-5) at 1200-1600 °C. Olivine co-precipitating with diamond from dry carbonate-silicate or hydrous-silicic fluid/melt can provide information on the H 2O contents and speciation of the diamond-forming media in the mantle. The conditions for minimum post-crystallization alteration of olivine and its hydrogen content are discussed.

  18. The stability of sapphirine + quartz in magnetite-bearing high oxygen fugacity granulites: a case study of the Madurai Block (Southern India) and the Inner Mongolia Suture Zone (North China)

    NASA Astrophysics Data System (ADS)

    Shimizu, H.; Tsunogae, T.; Santosh, M.

    2012-04-01

    Sapphirine has been the focus of many petrological investigations for the last two decades as the mineral often occurs in Mg-Al rich and pelitic rocks formed at high temperature to ultrahigh temperature (UHT). Particularly, sapphirine coexisting with quartz is considered as one of the most diagnostic mineral assemblages of UHT metamorphism. It is also known that sapphirine often occurs in magnetite-bearing high oxygen fugacity rocks, and, in such cases, the mineral can incorporate considerable quantity of ferric iron as well as Fe2+. It is therefore important to evaluate the effect of Fe3+ content on the stability of sapphirine-bearing assemblages for estimating peak conditions as well as constructing P-T paths. In this study, we evaluated the stability of sapphirine + quartz in magnetite-bearing high-oxygen fugacity rocks in UHT granulites from India (Madurai Block in the southern granulite terrane) and China (Inner Mongolia Suture Zone) using mineral equilibrium modeling technique, and constructed P-T paths of the areas. The calculations have been done in NCKFMASHTO system using THERMOCALC 3.33 with an updated version of the internally consistent data set. The Madurai Block is the largest granulite block in the Southern Granulite Terrane, India, which was formed by collisional orogeny related to the assembly of the Gondwana Supercontinent. The block contains granulites with various UHT mineral assemblages including sapphirine + quartz, orthopyroxene + sillimanite + quartz, and Al-rich orthopyroxene. Quartzo-feldspathic garnet-sillimanite granulites from Rajapalaiyam area in the southern part of the block, for example, contain sapphirine + quartz inclusion in garnet as a stable mineral assemblage at the peak of metamorphism. The calculated T-X pseudosections suggest that the stability temperature of sapphirine + quartz is lowered from 1000°C at reduced condition (XFe2O3 = 0.02) to 910°C at oxidized condition (XFe2O3 = 1.0). The Inner Mongolia Suture Zone within the North China Block rarely contains sapphirine-bearing UHT granulites. Tuguiwula area within the suture zone contains coarse-grained sapphirine granulites. Although both sapphirine and quartz occur quartzo-feldspathic layers of the rocks, the two minerals are separated by thin film of sillimanite. This indicates sapphirine was in equilibrium with quartz at prograde or peak metamorphic conditions and separated during retrograde metamorphism. The T-X pseudosection of the rocks indicate that the stability field of sapphirine + quartz lowered in more oxidized condition (T > 1050°C at XFe2O3 = 0.1 to T > 920°C at XFe2O3 = 0.9). The results of this study demonstrated that the occurrence of sapphirine + quartz in UHT rocks is strongly controlled by the oxidation state of the rocks. Lowering of the stability field of sapphirine + quartz by increasing XFe2O3 ratio was also confirmed for UHT granulites from the Madurai Block and the Inner Mongolia Suture Zone.

  19. MHD performance calculations with oxygen enrichment

    NASA Technical Reports Server (NTRS)

    Pian, C. C. P.; Staiger, P. J.; Seikel, G. R.

    1979-01-01

    The impact of oxygen enrichment of the combustion air on the generator and overall plant performance was studied for the ECAS-scale MHD/steam plants. A channel optimization technique is described and the results of generator performance calculations using this technique are presented. Performance maps were generated to assess the impact of various generator parameters. Directly and separately preheated plant performance with varying O2 enrichment was calculated. The optimal level of enrichment was a function of plant type and preheat temperature. The sensitivity of overall plant performance to critical channel assumptions and oxygen plant performance characteristics was also examined.

  20. 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 in the other samples. Metallic phases in all samples were melted at 1673 K. In the experiments about the starting materials (i), (ii) and (iv) at 15 GPa, Fe3C was formed at about 1073 K and Fe7C3 was formed at 1273 K. In the samples (ii) and (iv), FeSi was formed with Fe7C3 at 1273 K. This indicates that carbon reacts with metallic iron and any carbonates were not observed under the present experimental conditions. Therefore, these results may suggest that carbon exists in the mantle and/or core in some carbon-planets and carbon-bearing phases could be graphite/diamond, SiC and Fe-C alloy or Fe-Si-C alloy depending on the redox conditions at high pressure.

  1. 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 (?IW = -2.4 ~ -1.7) to Fe-Si composition (Si = 18 wt.%) in the more reducing condition (?IW < -4.8). SiC grains were also found in the most reducing condition. The solubility of C into the Fe-melt phase increases with fO2, whereas the solubility of Si decreases with increasing fO2. Based on in situ X-ray diffraction experiments, Fe3C was formed at 1073 K in the all samples. Fe3C peak disappeared and FeSi and SiC peaks appeared at 1373 K in the most reducing sample (v), whereas Fe3C remained in the other samples. Metallic phases in all samples were melted at 1673 K. Any carbonates was not observed under the present experimental conditions. Therefore, carbon-bearing phases are graphite, SiC and Fe-C alloy or Fe-Si-C alloy in the present redox conditions at 4 GPa. These results may suggest existence of carbon in the mantle and/or core in some carbon-planets.

  2. P-T-Fluid evolution and graphite deposition during retrograde metamorphism in Ribeira Fold Belt, SE Brazil: Oxygen fugacity, fluid inclusions and C-O-H isotopic evidence

    NASA Astrophysics Data System (ADS)

    Bento dos Santos, Telmo M.; Munhá, José M. U.; Tassinari, Colombo C. G.; Noronha, Fernando M.; Guedes, Alexandra; Fonseca, Paulo E.; Neto, Coriolano Dias; Dória, Armanda

    2011-02-01

    Combined fluid inclusion (FI) microthermometry, Raman spectroscopy, X-ray diffraction, C-O-H isotopes and oxygen fugacities of granulites from central Ribeira Fold Belt, SE Brazil, provided the following results: i) Magnetite-Hematite ƒO2 estimates range from 10-11.5 bar (QFM +1) to 10-18.3 bar (QFM -1) for the temperature range of 896 °C-656 °C, implying ƒO2 decrease from metamorphic peak temperatures to retrograde conditions; ii) 5 main types of fluid inclusions were observed: a) CO2 and CO2-N2 (0-11 mol%) high to medium density (1.01-0.59 g/cm3) FI; b) CO2 and CO2-N2 (0-36 mol%) low density (0.19-0.29 g/cm3) FI; c) CO2 (94-95 mol%)-N2 (3 mol%)-CH4 (2-3 mol%)-H2O (water ?v (25 °C) = 0.1) FI; d) low-salinity H2O-CO2 FI; and e) late low-salinity H2O FI; iii) Raman analyses evidence two graphite types in khondalites: an early highly ordered graphite (T?450 °C) overgrown by a disordered kind (T?330 °C); iv) ?18O quartz results of 10.3-10.7‰ imply high-temperature CO2 ?18O values of 14.4-14.8‰, suggesting the involvement of a metamorphic fluid, whereas lower temperature biotite ?18O and ?D results of 7.5-8.5‰ and -54 to -67‰, respectively imply H2O ?18O values of 10-11‰ and ?DH2O of -23 to -36‰, suggesting ?18O depletion and increasing fluid/rock ratio from metamorphic peak to retrograde conditions. Isotopic results are compatible with low-temperature H2O influx and ƒO2 decrease that promoted graphite deposition in retrograde granulites, simultaneous with low density CO2, CO2-N2 and CO2-N2-CH4-H2O fluid inclusions at T = 450-330 °C. Graphite ?13C results of -10.9 to -11.4‰ imply CO2 ?13C values of -0.8 to -1.3‰, suggesting decarbonation of Cambrian marine carbonates with small admixture of lighter biogenic or mantle derived fluids. Based on these results, it is suggested that metamorphic fluids from the central segment of Ribeira Fold Belt evolved to CO2-N2 fluids during granulitic metamorphism at high ƒO2, followed by rapid pressure drop at T?400-450 °C during late exhumation that caused ƒO2 reduction induced by temperature decrease and water influx, turning carbonic fluids into CO2-H2O (depleting biotite ?18O and ?D values), and progressively into H2O. When ƒO2 decreased substantially by mixture of carbonic and aqueous fluids, graphite deposited forming khondalites.

  3. Control of the water fugacity at high pressures and temperatures: Applications to the incorporation mechanisms of water in olivine

    E-print Network

    Control of the water fugacity at high pressures and temperatures: Applications to the incorporation t A new method is developed to control water fugacity at a fixed pressure and temperature. We use two. The chemical environment of the olivine crystal was controlled by the water fugacity buffer, the Ni­NiO oxygen

  4. 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.

  5. 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 form economic deposits of these metals. On the other hand, the reduced ore fluid models of D. A. Sverjensky (Econ. Geol., 1984, 79, 23–37) and T. H. Giordano and H. L. Barnes (Econ. Geol., 1981, 76, 2200–2211) can at best transport amounts of Pb and Zn, as carboxylate complexes, that are many orders of magnitude below the 1 to 10 ppm minimum required to form economic deposits. Lead and zinc speciation (mol% of total Pb or Zn) in the model ore fluid was calculated at specific log –pH conditions along the 100, 0.01, and 0.001 ppm total Pb and total Zn isopleths. Along the 100 ppm isopleth conditions are oxidized (?SO4 >> ?H2S) with Pb and Zn predominantly in the form of chloride complexes under acid to mildly alkaline conditions (pH from 3 to approximately 7.5), while hydroxide complexes dominate Pb and Zn speciation under more alkaline conditions. Sulfide complexes are insignificant under these oxidized conditions. For more reduced conditions along the 0.01 and 0.001 ppm isopleths chloride complexes dominate Pb and Zn speciation in the SO42- field and near the SO42--reduced sulfur boundary from pH = 4 to approximately 7.5, while hydroxide complexes dominate Pb and Zn speciation under alkaline conditions above pH = 7.5 in the SO42- field. In the most reduced fluids (?H2S >> ?SO4) along the 0.01 and 0.001 isopleths, sulfide complexes account for almost 100% of the Pb and Zn in the model fluid. Acetate (monocarboxylate) complexation is significant only under conditions of chloride and hydroxide complex dominance and its effect is maximized in the pH range 5 to 7, where it complexes 2 to 2.6% of the total Pb and 1 to 1.25% of the total Zn. Malonate (dicarboxylate) complexes are insignificant along all isopleths. The speciation results from this study show that deep formation waters characterized by temperatures near 100°C, high oxidation states and ?H2S < 0.03 mg L-1 ( < 10-6), high chlorinities (~ 100000 mg L-1), and high but reasonable concentrations of carboxyla

  6. A liquid oxygen calculator for fasted channel catfish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An interactive liquid oxygen (LOX) calculator for fasted channel catfish confined in grading nets or in live haul tanks has been developed, using Microsoft Visual Studio 2005©. The calculator is based on results of scientific experiments on channel catfish metabolism, and estimates oxygen consumptio...

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

    USGS Publications Warehouse

    Hass, J.L., Jr.

    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. ?? 1970.

  8. 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.

  9. Fugacity and Reheating of Primordial Neutrinos

    NASA Astrophysics Data System (ADS)

    Birrell, Jeremiah; Yang, Cheng-Tao; Chen, Pisin; Rafelski, Johann

    2013-12-01

    We clarify in a quantitative way the impact that distinct chemical Tc and kinetic Tk freeze-out temperatures have on the reduction of the neutrino fugacity ?? below equilibrium, i.e. ??<1, and the increase of the neutrino temperature T? via partial reheating. We establish the connection between ?? and Tk via the modified reheating relation T?(??)/T?, where T? is the temperature of the background radiation. Our results demonstrate that one must introduce the chemical nonequilibrium parameter, i.e. the fugacity, ??, as an additional standard cosmological model parameter in the evaluation of CMB fluctuations as its value allows measurement of Tk.

  10. Quark number susceptibilities at finite chemical potential from fugacity expansion

    E-print Network

    Hans-Peter Schadler; Christof Gattringer

    2014-09-16

    Generalized quark number susceptibilities are expected to be good probes for the phase transitions in QCD and the search of a possible critical point. However, their computation in lattice QCD is plagued by the complex action problem which appears at finite chemical potential mu. In this work we explore the possibilities of an expansion in the fugacity parameter exp(mu beta) which has features that make, in particular quark number related bulk observables easily accessible. We present results at finite chemical potential for generalized susceptibilities up to the 4th order as well as their ratios and compare them to model calculations.

  11. Significance of pathologic oxygen supply dependency in critically ill patients: Comparison between measured and calculated methods

    Microsoft Academic Search

    G. Hanique; T. Dugernier; P. F. Laterre; A. Dougnac; J. Roeseler; M. S. Reynaert

    1994-01-01

    Objective  Oxygen supply dependency at normal or high oxygen delivery rate has been increasingly proposed as a hallmark and a risk factor\\u000a in critical illnesses. We hypothesized that as fas as an adequate oxygen delivery is provided, oxygen consumption, when determined\\u000a by indirect calorimetry, is not dependent on oxygen delivery in critically ill patients whereas calculated oxygen consumption\\u000a is associated with

  12. 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

  13. Theoretical calculations on the reaction of ethylene with oxygen

    NASA Astrophysics Data System (ADS)

    Hua, Hou; Ruscic, Branko; Wang, Baoshan

    2005-05-01

    The triplet potential energy surface for the reaction of ethylene with molecular oxygen in the ground state has been calculated at the QCISD(T, full)/6-311++G(3df,2p)//MP2(full)/6-311G(d,p) level of theory. Four intermediates and 17 transition states are located along the minimum energy reaction path. Six major radical product channels are revealed, namely, C 2H 3 + HO 2, O( 3P) + C 2H 4O, H + C 2H 3O 2, OH + C 2H 3O, OH + CH 3CO, and O( 3P) + CH 3CHO. In view of reaction barrier heights, the dominant channels are predicted to be C 2H 3 + HO 2, O( 3P) + C 2H 4O, H + C 2H 3O 2, and C 2H 4O 2( 3A?). The calculated rate constants for the abstraction reaction path are in good agreement with the available experimental data. The implication of the current results in the initiation of the combustion of ethylene is discussed.

  14. Semi-empirical estimation of organic compound fugacity ratios at environmentally relevant system temperatures.

    PubMed

    van Noort, Paul C M

    2009-06-01

    Fugacity ratios of organic compounds are used to calculate (subcooled) liquid properties, such as solubility or vapour pressure, from solid properties and vice versa. They can be calculated from the entropy of fusion, the melting temperature, and heat capacity data for the solid and the liquid. For many organic compounds, values for the fusion entropy are lacking. Heat capacity data are even scarcer. In the present study, semi-empirical compound class specific equations were derived to estimate fugacity ratios from molecular weight and melting temperature for polycyclic aromatic hydrocarbons and polychlorinated benzenes, biphenyls, dibenzo[p]dioxins and dibenzofurans. These equations estimate fugacity ratios with an average standard error of about 0.05 log units. In addition, for compounds with known fusion entropy values, a general semi-empirical correction equation based on molecular weight and melting temperature was derived for estimation of the contribution of heat capacity differences to the fugacity ratio. This equation estimates the heat capacity contribution correction factor with an average standard error of 0.02 log units for polycyclic aromatic hydrocarbons, polychlorinated benzenes, biphenyls, dibenzo[p]dioxins and dibenzofurans. PMID:19304312

  15. Fixed-fugacity option for the EQ6 geochemical reaction path code

    SciTech Connect

    Delany, J.M.; Wolery, T.J.

    1984-12-20

    EQ3/6 is a software package used to model aqueous geochemical systems. The EQ6 code allows reaction paths of dynamic systems to be calculated. This report describes a new option for the EQ6 computer program that permits the fugacity of any gas in the EQ6 data base to be set to a fixed value. This capability permits simulation of the effect of rapid chemical exchange with a large external gas reservoir by allowing the user to fix the fugacities of selected gas species. Geochemical environments such as groundwater systems open to the atmosphere (e.g., the unsaturated zone), natural aqueous systems that form closed systems at depth, and experimental systems that use controlled atmospheres can be modeled. Two of the principal geochemical weathering agents, CO{sub 2} and O{sub 2}, are the most likely gas species for which this type of exchange may be important. An example of the effect of constant CO{sub 2} fugacity on both open and closed systems is shown for the case of albite dissolution (NaAlSi{sub 3}O{sub 8}) in distilled water. This example demonstrates that the effects of imposed fugacities on geochemical systems can be considerable. This computer code is used in the Nevada Nuclear Waste Storage Investigations Project. 15 refs., 8 figs.

  16. CALCULATIONS OF OXYGEN TRANSPORT BY RED BLOOD CELLS

    E-print Network

    Popel, Aleksander S.

    capillary. The model mainly focuses on low capillary hema- tocrits and studies the effect of free hemoglobin of RBCs (hematocrit) in the blood is small, in sickle cell anemia, for perioperative uses in surgery, intraluminal resistance to oxygen transport was neglected in modeling studies under the tacit assumption

  17. A liquid oxygen calculator for fasted channel catfish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A review of scientific literature concerning channel catfish Ictalurus punctatus respiration resulted in development of a Microsoft Excel© spreadsheet for estimating the volume of oxygen consumed by a given fasted channel catfish biomass. Entry of ten variables into the spreadsheet provides estimate...

  18. 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. (UNM); (ESC); (UC)

    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.

  19. Calculations of the Heat Release Rate by Oxygen Consumption for Various Applications

    Microsoft Academic Search

    W. J. Parker

    1984-01-01

    The calculation of heat release rate by oxygen consumption is based on the assumption that all materials release approximately the same amount of heat per unit mass of oxygen consumed. This technique is now being employed to determine the heat release rate of materials in various heat release rate cal orimeters. Other uses include the heat release rate of assemblies

  20. The Evolution and Future of Environmental Fugacity Models

    Microsoft Academic Search

    Donald Mackay; Jon A. Arnot; Eva Webster; Lüsa Reid

    \\u000a In this chapter we first review the concept of fugacity as a thermodynamic equilibrium criterion applied to chemical fate\\u000a in environmental systems. We then discuss the evolution of fugacity-based models applied to the multimedia environmental distribution\\u000a of chemicals and more specifically to bioaccumulation and food web models. It is shown that the combination of multimedia\\u000a and bioaccumulation models can provide

  1. 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.

  2. The effects of sulfur, silicon, water, and oxygen fugacity on carbon solubility and partitioning in Fe-rich alloy and silicate melt systems 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, Yuan; Dasgupta, Rajdeep; Tsuno, Kyusei

    2015-04-01

    The partition coefficient of carbon between Fe-rich alloy melt and silicate melt, DCmetal/silicate and solubility of C-O-H volatiles in reduced silicate melts are key parameters that need to be quantified in order to constrain the budget and origin 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, determined by electron microprobe, whereas the presence of 0-10 wt% silicon decreases the carbon solubility from ?5.6 wt% to 1.8 wt%. Carbon solubility (11-192 ppm) in silicate melt, determined by SIMS, is strongly controlled by fO2 and the bulk water content. Decreasing log ? 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 spectroscopic analyses of silicate glasses show that the carbon species is mostly methane, which is further confirmed by the strong, positive correlation between the non-carbonate carbon and non-hydroxyl hydrogen in silicate melt. The DCmetal/silicate ranging from 180 to 4600 decreases with decreasing fO2 or increasing bulk water in silicate melt. In addition, increasing Si in alloy melt also decreases DCmetal/silicate. Our results demonstrate that fO2 and bulk water contents in silicate melt play an important role in determining 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 into 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 DCmetal/silicate > 1000, most early Earth carbon would also enter the segregating core. Finally, the predominance of methane in reduced silicate melt with fO2 below IW-1 also indicates that degassing of a hydrous, solidifying MO may have created a reduced early atmosphere, and degassing from lunar and Martian mantle may have released much more methane than carbon dioxide.

  3. Similarity criteria in calculations of the energy characteristics of a cw oxygen - iodine laser

    NASA Astrophysics Data System (ADS)

    Mezhenin, A. V.; Azyazov, V. N.

    2012-12-01

    The calculated and experimental data on the energy efficiency of a cw oxygen - iodine laser (OIL) are analysed based on two similarity criteria, namely, on the ratio of the residence time of the gas mixture in the resonator to the characteristic time of extraction of the energy stored in singlet oxygen td and on the gain-to-loss ratio ?. It is shown that the simplified two-level laser model satisfactorily predicts the output characteristics of OILs with a stable resonator at ?d <= 7. Efficient energy extraction from the OIL active medium is achieved in the case of ?d = 5 - 7, ? = 4 - 8.

  4. Similarity criteria in calculations of the energy characteristics of a cw oxygen - iodine laser

    SciTech Connect

    Mezhenin, A V; Azyazov, V N

    2012-12-31

    The calculated and experimental data on the energy efficiency of a cw oxygen - iodine laser (OIL) are analysed based on two similarity criteria, namely, on the ratio of the residence time of the gas mixture in the resonator to the characteristic time of extraction of the energy stored in singlet oxygen td and on the gain-to-loss ratio {Pi}. It is shown that the simplified two-level laser model satisfactorily predicts the output characteristics of OILs with a stable resonator at {tau}{sub d} {<=} 7. Efficient energy extraction from the OIL active medium is achieved in the case of {tau}{sub d} = 5 - 7, {Pi} = 4 - 8. (lasers)

  5. Uncertainties in the thermodynamics of basalt-oxygen and basalt-water reactions

    SciTech Connect

    Schweitzer, D.G.; Davis, M.S.

    1983-08-01

    A knowledge of basalt-oxygen equilibria and basalt-water equilibria are required to predict the performance of a high-level waste package in a basalt repository. In this report we have evaluated uncertainties in these equilibria using thermodynamic data from two sources, the JANAF Thermochemical Tables (1971) and from Kubaschewski (1974). Our analysis indicates that the uncertainties in the basic thermodynamic data lead to 30 orders of magnitude in uncertainty in the oxygen fugacity for the magnetite-hematite reaction (10/sup -57/ to 10/sup -86/ atm) and about 15 orders of magnitude uncertainty in the hydrogen equilibrium pressure (10/sup -12/ to 10/sup +3/ atm). A vast volume of literature exists on reactions involving magnetite and hematite in water at temperatures pertinent to basalt repositories (50/sup 0/ to 350/sup 0/C). These data show that Fe/sub 3/O/sub 4/ and Fe/sub 2/O/sub 3/ can coexist in water with oxygen fugacities from about 10/sup -4/ to 1 rather than the calculated oxygen fugacities of approx. 10/sup -60/ to 10/sup -30/ assumed in the past. 5 references.

  6. ccsd-00000318(version1):29Apr2003 Calculation of muon transfer from muonic hydrogen to atomic oxygen

    E-print Network

    Boyer, Edmond

    oxygen Arnaud Dupays, Bruno Lepetit, J. Alberto Beswick, Carlo Rizzo Laboratoire Collisions, Agrgats and an oxygen atom are calculated in a constrained geometry one dimensional model for collision energies between energy dependence of muon transfer from the muonic hydrogen to an oxygen molecule, has been proposed [3

  7. Ocean Surface Carbon Dioxide Fugacity and Flux From Space

    Microsoft Academic Search

    W. Liu; X. Xie

    2010-01-01

    The ocean as the source and sink of carbon dioxide is important to global warming and ecology. We estimate the ocean-atmosphere exchanges in carbon dioxide through turbulence parameterization, which requires the difference in fugacity of carbon dioxide between sea and air, and a transfer velocity. There have been many studies on the parameterization of the transfer velocity in term of

  8. 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…

  9. Calculation of the relative metastabilities of proteins in subcellular compartments of Saccharomyces cerevisiae

    E-print Network

    Jeffrey M. Dick

    2008-12-01

    [abridged] Background: The distribution of chemical species in an open system at metastable equilibrium can be expressed as a function of environmental variables which can include temperature, oxidation-reduction potential and others. Calculations of metastable equilibrium for various model systems were used to characterize chemical transformations among proteins and groups of proteins found in different compartments of yeast cells. Results: With increasing oxygen fugacity, the relative metastability fields of model proteins for major subcellular compartments go as mitochondrion, endoplasmic reticulum, cytoplasm, nucleus. In a metastable equilibrium setting at relatively high oxygen fugacity, proteins making up actin are predominant, but those constituting the microtubule occur with a low chemical activity. A reaction sequence involving the microtubule and spindle pole proteins was predicted by combining the known intercompartmental interactions with a hypothetical program of oxygen fugacity changes in the local environment. In further calculations, the most-abundant proteins within compartments generally occur in relative abundances that only weakly correspond to a metastable equilibrium distribution. However, physiological populations of proteins that form complexes often show an overall positive or negative correlation with the relative abundances of proteins in metastable assemblages. Conclusions: This study explored the outlines of a thermodynamic description of chemical transformations among interacting proteins in yeast cells. The results suggest that these methods can be used to measure the degree of departure of a natural biochemical process or population from a local minimum in Gibbs energy.

  10. Calculation of formation energy of oxygen vacancy in ZnO based on photoluminescence measurements.

    PubMed

    Kim, Yongseon; Kang, Shinhoo

    2010-06-17

    The formation energy of an oxygen vacancy in ZnO was calculated. The photoluminescence intensity of green emission was used as a measure of vacancy concentration, and its variation as a function of reduction temperature was monitored. This enabled a thermodynamic approach based on experimental data, which is in contrast with most previous studies, which focused on a theoretical treatment based on first principles methods. Two reduction conditions were used: hydrogen gas flow and a CO/CO(2) atmosphere generated using activated carbon. The two cases were compared, and mechanisms for the formation of oxygen vacancies during thermal treatment were investigated. The similar results obtained for the two cases indicate that the proposed models of V(O) formation are reasonable. PMID:20499883

  11. 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.

  12. Analytic calculations of ozone concentration in an oxygen-fed DBD cylindrical ozonizer

    NASA Astrophysics Data System (ADS)

    Held, B.

    2000-08-01

    An analytical model for ozone concentration calculation, previously described in [CITE], is applied to an oxygen-fed DBD cylindrical ozonizer. It is shown that this model can be applied to DC or DBD discharges, using an appropriate temperature law in the reaction zone. The ozone concentration, the overall parameters for ozone formation and destruction, the specific energy and the economical criterion are presented as functions of the ozonizer geometry, the electric power, the fluid flow, the temperature and the pressure. These results are compared to industrial data and a good agreement is observed.

  13. Comparison of calculated with measured oxygen consumption in children undergoing cardiac catheterization.

    PubMed

    Schmitz, Achim; Kretschmar, Oliver; Knirsch, Walter; Woitzek, Katja; Balmer, Christian; Tomaske, Maren; Bauersfeld, Urs; Weiss, Markus

    2008-11-01

    Our objective was to compare calculated (LaFarge) with measured oxygen consumption (VO(2)) using the AS/3 TM Compact Airway Module M-CAiOVX (Datex-Ohmeda, Helsinki, Finland; AS/3 TM) in children without cardiac shunts in a prospective, observational study. VO(2) was determined at the end of the routine diagnostic and/or interventional catheterization. VO(2 )was calculated according to the formula of LaFarge and Miettinen for each child and compared with the measured VO(2). Data were compared using simple regression and Bland Altman analysis. Fifty-two children aged from 0.5 to 16 years (median, 6.9 years) and weighing 3.4 to 59.4 kg (median, 22.9 kg) were investigated. Calculated VO(2 )values ranged from 59.0 to 230.8 ml/min, and measured VO(2) values from 62.7 to 282.2 ml/min. Comparison of calculated versus measured VO(2) values revealed a significant correlation (r = 0.90, p < 0.0001). Bias and precision were 8.9 and 48.3 ml/min, respectively (95% limits of agreement: -39.4 to 57.2 ml/min). Comparison of calculated VO(2) in children older than 3 years (n = 41), as restricted to the formula, with measured VO(2), revealed a slightly reduced correlation (r = 0.86, p < 0.0001). Bias and precision were 10.0 and 52.5 ml/min, respectively (95% limits of agreement: -42.4 to 62.5 ml/min). We conclude that calculation of VO(2) by the LaFarge formula does not provide reliable values compared to measured values. In clinical routine, measured rather than calculated VO(2) values should be used for the estimation of cardiac output and related variables. PMID:18592299

  14. Ab Initio Calculations of Even Oxygen Isotopes with Chiral Two- Plus Three-Nucleon Interactions

    E-print Network

    Hergert, H; Calci, A; Langhammer, J; Roth, R

    2013-01-01

    We formulate the In-Medium Similarity Renormalization Group (IM-SRG) for open-shell nuclei using a multi-reference formalism based on a generalized Wick theorem introduced in quantum chemistry. The resulting multi-reference IM-SRG (MR-IM-SRG) is used to perform the first ab initio study of even oxygen isotopes with chiral NN and 3N Hamiltonians, from the proton to the neutron drip lines. We obtain an excellent reproduction of experimental ground-state energies with quantified uncertainties, which is validated by results from the Importance-Truncated No-Core Shell Model and the Coupled Cluster method. The agreement between conceptually different many-body approaches and experiment highlights the predictive power of current chiral two- and three-nucleon interactions, and establishes the MR-IM-SRG as a promising new tool for ab initio calculations of medium-mass nuclei far from shell closures.

  15. Ab Initio Calculations of Even Oxygen Isotopes with Chiral Two-Plus-Three-Nucleon Interactions

    NASA Astrophysics Data System (ADS)

    Hergert, H.; Binder, S.; Calci, A.; Langhammer, J.; Roth, R.

    2013-06-01

    We formulate the in-medium similarity renormalization group (IM-SRG) for open-shell nuclei using a multireference formalism based on a generalized Wick theorem introduced in quantum chemistry. The resulting multireference IM-SRG (MR-IM-SRG) is used to perform the first ab initio study of all even oxygen isotopes with chiral nucleon-nucleon and three-nucleon interactions, from the proton to the neutron drip lines. We obtain an excellent reproduction of experimental ground-state energies with quantified uncertainties, which is validated by results from the importance-truncated no-core shell model and the coupled cluster method. The agreement between conceptually different many-body approaches and experiment highlights the predictive power of current chiral two- and three-nucleon interactions, and establishes the MR-IM-SRG as a promising new tool for ab initio calculations of medium-mass nuclei far from shell closures.

  16. Thin-Film Solid-Phase Extraction To Measure Fugacities of Organic

    E-print Network

    Gobas, Frank

    Thin-Film Solid-Phase Extraction To Measure Fugacities of Organic Chemicals with Low Volatility of ethylene vinyl acetate coated on glass surfaces are used as solid- phase samplers of contaminated). Techniques for making fugacity measurements in animal tissues do not exist to date. Recently, solid

  17. First-principles calculations of oxygen vacancy formation and metallic behavior at a ?-MnO2 grain boundary.

    PubMed

    Dawson, James A; Chen, Hungru; Tanaka, Isao

    2015-01-28

    Nanostructured MnO2 is renowned for its excellent energy storage capability and high catalytic activity. While the electronic and structural properties of MnO2 surfaces have received significant attention, the properties of the grain boundaries (GBs) and their contribution to the electrochemical performance of the material remains unknown. Through density functional theory (DFT) calculations, the structure and electronic properties of the ?-MnO2 ? 5(210)/[001] GB are studied. Our calculations show this low energy GB has a significantly reduced band gap compared to the pristine material and that the formation of oxygen vacancies produces spin-polarized states that further reduce the band gap. Calculated formation energies of oxygen vacancy defects and Mn reduction at the GB core are all lower than the equivalent bulk value and in some cases lower than values recently calculated for ?-MnO2 surfaces. Oxygen vacancy formation is also shown to produce a metallic behavior at the GB with defect charge distributed over a number of oxygen and manganese sites. The low energies of oxygen defect formation and the potential creation of conductive GB pathways are likely to be important to the electrochemical performance of ?-MnO2. PMID:25559707

  18. Oxygen and dioxygen centers in Si and Ge: Density-functional calculations

    NASA Astrophysics Data System (ADS)

    Coutinho, J.; Jones, R.; Briddon, P. R.; Öberg, S.

    2000-10-01

    Ab initio density-functional calculations using Gaussian orbitals are carried out on large Si and Ge supercells containing oxygen defects. The formation energies, local vibrational modes, and diffusion or reorientation energies of Oi, O2i, VO, VOH, and VO2 are investigated. The piezospectroscopic tensors for Oi, VO, and VO2 are also evaluated. The vibrational modes of Oi in Si are consistent with the view that the defect has effective D3d symmetry at low hydrostatic pressures but adopts a buckled structure for large pressures. The anomalous temperature dependence of the modes of O2i is attributed to an increased buckling of Si-O-Si when the lattice contracts. The diffusion energy of the dimer is around 0.8 eV lower than that of Oi in Si and 0.6 eV in Ge. The dimer is stable against VO or VO2 formation and the latter defect has modes close to the reported 894-cm-1 band. The reorientation energies for O and H in VO and VOH defects are found to be a few tenths of an eV and are greater when the defect has trapped an electron.

  19. 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. PMID:23201099

  20. Inhibition of biocatalysis in [Fe-Fe] hydrogenase by oxygen: molecular dynamics and density functional theory calculations.

    PubMed

    Hong, Gongyi; Pachter, Ruth

    2012-07-20

    Designing O(2)-tolerant hydrogenases is a major challenge in applying [Fe-Fe]H(2)ases for H(2) production. The inhibition involves transport of oxygen through the enzyme to the H-cluster, followed by binding and subsequent deactivation of the active site. To explore the nature of the oxygen diffusion channel for the hydrogenases from Desulfovibrio desulfuricans (Dd) and Clostridium pasteurianum (Cp), empirical molecular dynamics simulations were performed. The dynamic nature of the oxygen pathways in Dd and Cp was elucidated, and insight is provided, in part, into the experimental observation on the difference of oxygen inhibition in Dd and the hydrogenase from Clostridium acetobutylicum (Ca, assumed homologous to Cp). Further, to gain an understanding of the mechanism of oxygen inhibition of the [Fe-Fe]H(2)ase, density functional theory calculations of model compounds composed of the H-cluster and proximate amino acids are reported. Confirmation of the experimentally based suppositions on inactivation by oxygen at the [2Fe](H) domain is provided, validating the model compounds used and oxidation state assumptions, further explaining the mode of damage. This unified approach provides insight into oxygen diffusion in the enzyme, followed by deactivation at the H-cluster. PMID:22563793

  1. Virial Approximation of the TEOS-10 Equation for the Fugacity of Water in Humid Air

    NASA Astrophysics Data System (ADS)

    Feistel, Rainer; Lovell-Smith, Jeremy W.; Hellmuth, Olaf

    2015-01-01

    Fugacity is considered the proper real-gas substitute for the partial pressure commonly used to describe ideal-gas mixtures. However, in several fields such as geophysics, meteorology, or air conditioning, partial pressure is still preferred over fugacity when non-equilibrium conditions of humid air are quantified. One reason may be that for ambient air, the deviations from ideal-gas behavior are small, another that explicit correlation equations for the fugacity of water vapor in humid air are scarce in the literature. This situation has improved with the publication of the new oceanographic standard TEOS-10, the International Thermodynamic Equation of Seawater 2010, which provides highly accurate values for the chemical potential and the fugacity of water vapor in humid air over wide ranges of pressure and temperature. This paper describes the way fugacity is obtained from the fundamental equations of TEOS-10, and it derives computationally more convenient virial approximations for the fugacity, consistent with TEOS-10. Analytically extracted from the TEOS-10 equation of state of humid air, equations for the 2nd and 3rd virial coefficients are reported and compared with correlations available from the literature. The virial fugacity equation is valid in the temperature range between and +200 at pressures up to 5 MPa, and between and +1000 at low pressures such as those encountered in the terrestrial atmosphere at higher altitudes.

  2. 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.

  3. 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 ?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 (?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. PMID:24344312

  4. 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. PMID:11541456

  5. 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.

  6. 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 ?15N. Consequently, correction factors need to be applied to appropriately interpret ?13C and ?15N 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 ?13C values after lipid extraction (??13C) varied widely among categories (eg., species, tissue type) from 0 - 4 ‰, while ??15N values ranged from 0 to 2‰. Notably, within category variation was nonsignificant and the ?? 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 ??13C and ??15N among data categories. Clearly, understanding the nature of variation and the physiological processes responsible for stable isotope values from biological tissues are critical for their interpretation. Change in carbon and nitrogen stable isotopes (??C13, ??15N) after lipid extraction for Tufted Puffins (Fratercula cirrhata) collected July 2010 at Attu Island, Aleutians.

  7. 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.

  8. 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.

    2011-10-01

    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 17?P and 18?P for 17O/16O and 18O/16O, respectively). This comment has no merit for the following reasons: (a) the isotopic composition of photosynthetic oxygen cannot be "defined", it can only be measured, modelled or calculated based on other data; (b) the isotopic composition of photosynthetic oxygen was not "defined" in Kaiser (2011a), but derived from published measurements; (c) the published measurements themselves were inconsistent and no single result could be identified as best; (d) since no best value could be identified, a hypothetical base case was constructed in a way that was consistent with previous publications; (e) the values of 17?P=-11.646‰ and 18?P=-22.835‰ assumed for the base case are compatible with the experimental evidence published before the paper of Kaiser (2011a); (f) even if the "biological end-member" was based on a~definition, there could be no argument about the "consistency" of this definition - as per its nature, a definition is arbitrary. The qualification of base case gross production values as being "30 % too high" must therefore also be rejected. Even though recently revised measurements of the relative 17O/16O isotope ratio difference between VSMOW and Air-O2, 17?VSMOW (Barkan and Luz, 2011), do support lower estimates of gross production, our own measurements disagree with these revised 17?VSMOW values. If scaled for differences in 18?VSMOW, they are actually in good agreement with the original data (Barkan and Luz, 2005). Moreover, species-dependent differences in photosynthetic isotope fractionation (Eisenstadt et al., 2010) correspond to an uncertainty of at least 15 % around the central estimate for the inferred gross production. Nicholson (2011a) also suggests that approximated calculations of gross production should be performed with a triple isotope excess defined as 17?#≡ln(1+17?)-?ln(1+18?), with ?=?R=ln(1+17ϵR)/ln(1+18ϵR). However, this only improves the approximation for certain 17?P and 18?P values, for certain net to gross production ratios (f) and for certain ratios of gross production to gross Air-O2 invasion (g). In other cases, the approximated calculation based on 17?†≡17?-?18? with ?=?R=17ϵR/18ϵR gives better results.

  9. Use of a vial equilibration technique to measure the change in fugacity capacity of avian food and feces samples for 1,2,3,4-tetrachlorobenzene.

    PubMed

    Drouillard, Ken G; Norstrom, R J

    2014-11-01

    A vial equilibration technique was used to estimate the fugacity capacities of food and feces samples for 1,2,3,4-tetrachlorobenzene (TCB). The method was calibrated using different volumes of n-octanol and by comparing the measured and predicted fugacity capacity (Zoct) of n-octanol for TCB. The vial equilibration technique showed linearity with increasing amounts of n-octanol added to the vial. However, the measured Zoct was on average 8.5 times lower than the literature estimate and interpreted to be influenced by co-solvent effects. The ratio of fugacity capacities of food/feces was 2.9 and was consistent with the ratio estimated using Zt calculation methods (4.3) which considers partitioning capacity of both lipids and non-lipid organic matter. These results provide experimental support to the use of lipid equivalent approaches as opposed to lipid normalization when estimating the partition capacity of biological samples containing low lipid contents. PMID:24934706

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

    SciTech Connect

    Harlov, D.E. (Purdue Univ., West Lafayette, IN (United States))

    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.

  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. PMID:6257447

  12. 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 Lunar Metal Grains: Solar, Lunar or Terrestrial Origin? 22) Isotopic Zoning in the Inner Solar System; 23) Redox Conditions on Small Bodies; 24) Determining the Oxygen Fugacity of Lunar Pyroclastic Glasses Using Vanadium Valence - An Update; 25) Mantle Redox Evolution and the Rise of Atmospheric O2; 26) Variation of Kd for Fe-Mg Exchange Between Olivine and Melt for Compositions Ranging from Alkaline Basalt to Rhyolite; 27) Determining the Partial Pressure of Oxygen (PO,) in Solutions on Mars; 28) The Influence of Oxygen Environment on Kinetic Properties of Silicate Rocks and Minerals; 29) Redox Evolution of Magmatic Systems; 30) The Constancy of Upper Mantlefo, Through Time Inferred from V/Sc Ratios in Basalts: Implications for the Rise in Atmospheric 0 2; 31) Nitrogen Solubility in Basaltic Melt. Effects of Oxygen Fugacity, Melt Composition and Gas Speciation; 32) Oxygen Isotope Anomalies in the Atmospheres of Earth and Mars; 33) The Effect of Oxygen Fugacity on Interdiffusion of Iron and Magnesium in Magnesiowiistite 34) The Calibration of the Pyroxene Eu-Oxybarometer for the Martian Meteorites; 35) The Europium Oxybarometer: Power and Pitfalls; 36) Oxygen Fugacity of the Martian Mantle from PigeoniteMelt Partitioning of Samarium, Europium and Gadolinium; 37) Oxidation-Reduction Processes on the Moon: Experimental Verification of Graphite Oxidation in the Apollo 17 Orange Glasses; 38) Oxygen and Core Formation in the Earth; 39) Geologic Record of the Atmospheric Sulfur Chemistry Before the Oxygenation of the Early Earth s Atmosphere; 40) Comparative Planetary Mineralogy: V/(CrCAl) Systematics in Chromite as an Indicator of Relative Oxygen Fugacity; 41) How Well do Sulfur Isotopes Constrain Oxygen Abundance in the Ancient Atmospheres? 42) Experimental Constraints on the Oxygen Isotope (O-18/ O-16) Fractionation in the Ice vapor and Adsorbant vapor Systems of CO2 at Conditions Relevant to the Surface of Mars; 43) Micro-XANES Measurements on Experimental Spinels andhe Oxidation State of Vanadium in Spinel-Melt Pairs; 44) Testing the Magma Ocean Hypothesis Using

  13. Apparent oxygen utilization rates calculated from tritium and helium-3 profiles at the Bermuda Atlantic Time-series Study site

    NASA Astrophysics Data System (ADS)

    Stanley, R. H. R.; Doney, S. C.; Jenkins, W. J.; Lott, D. E., III

    2012-06-01

    We present three years of Apparent Oxygen Utilization Rates (AOUR) estimated from oxygen and tracer data collected over the ocean thermocline at monthly resolution between 2003 and 2006 at the Bermuda Atlantic Time-series Study (BATS) site. We estimate water ages by calculating a transit time distribution from tritium and helium-3 data. The vertically integrated AOUR over the upper 500 m, which is a regional estimate of export, during the three years is 3.1 ± 0.5 mol O2 m-2 yr-1. This is comparable to previous AOUR-based estimates of export production at the BATS site but is several times larger than export estimates derived from sediment traps or 234Th fluxes. We compare AOUR determined in this study to AOUR measured in the 1980s and show AOUR is significantly greater today than decades earlier because of changes in AOU, rather than changes in ventilation rates. The changes in AOU are likely a methodological artefact associated with problems with early oxygen measurements.

  14. Apparent oxygen utilization rates calculated from tritium and helium-3 profiles at the Bermuda Atlantic Time-series Study site

    NASA Astrophysics Data System (ADS)

    Stanley, R. H. R.; Doney, S. C.; Jenkins, W. J.; Lott, D. E., III

    2011-10-01

    We present three years of Apparent Oxygen Utilization Rates (AOUR) estimated from oxygen and tracer data collected over the ocean thermocline at monthly resolution between 2003 and 2006 at the Bermuda Atlantic Time-series Study (BATS) site. We estimate water ages by calculating a transit time distribution from tritium and helium-3 data. The vertically integrated AOUR over the upper 500 m, which is a regional estimate of export, during the three years is 3.1 ± 0.5 mol O2 m-2 yr-1. This is comparable to previous AOUR-based estimates of export production at the BATS site but is several times larger than export estimates derived from sediment traps or 234Th fluxes. We compare AOUR determined in this study to AOUR measured in the 1980s and show AOUR is significantly greater today than decades earlier because of changes in AOU, rather than changes in ventilation rates. The changes in AOU may be a methodological artefact associated with problems with early oxygen measurements.

  15. Electrical conductivity in oxygen-deficient phases of tantalum pentoxide from first-principles calculations

    NASA Astrophysics Data System (ADS)

    Bondi, Robert J.; Desjarlais, Michael P.; Thompson, Aidan P.; Brennecka, Geoff L.; Marinella, Matthew J.

    2013-11-01

    We apply first-principles density-functional theory (DFT) calculations, ab-initio molecular dynamics, and the Kubo-Greenwood formula 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+). In the crystalline phase, our DFT calculations suggest that VO0 prefers equatorial O sites, while VO1+ and VO2+ are energetically preferred in the O cap sites of TaO7 polyhedra. Our calculations of DC conductivity at 300 K agree well with experimental measurements taken on Ta2Ox thin films (0.18 ? x ? 4.72) 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. Furthermore, this dopant-like behavior is specific to the neutral case and not observed in either the 1+ or 2+ oxidation states, which suggests that reduction and oxidation reactions may effectively act as donor activation and deactivation mechanisms, respectively, for VOn in Ta2O5.

  16. Electrical conductivity in oxygen-deficient phases of tantalum pentoxide from first-principles calculations

    SciTech Connect

    Bondi, Robert J., E-mail: rjbondi@sandia.gov; Desjarlais, Michael P.; Thompson, Aidan P.; Brennecka, Geoff L.; Marinella, Matthew J. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2013-11-28

    We apply first-principles density-functional theory (DFT) calculations, ab-initio molecular dynamics, and the Kubo-Greenwood formula to predict electrical conductivity in Ta{sub 2}O{sub x} (0???x???5) as a function of composition, phase, and temperature, where additional focus is given to various oxidation states of the O monovacancy (V{sub O}{sup n}; n?=?0,1+,2+). In the crystalline phase, our DFT calculations suggest that V{sub O}{sup 0} prefers equatorial O sites, while V{sub O}{sup 1+} and V{sub O}{sup 2+} are energetically preferred in the O cap sites of TaO{sub 7} polyhedra. Our calculations of DC conductivity at 300?K agree well with experimental measurements taken on Ta{sub 2}O{sub x} thin films (0.18???x???4.72) and bulk Ta{sub 2}O{sub 5} 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 Ta{sub 2}O{sub 5} electronic structure provide further theoretical basis to substantiate V{sub O}{sup 0} as a donor dopant in Ta{sub 2}O{sub 5}. Furthermore, this dopant-like behavior is specific to the neutral case and not observed in either the 1+ or 2+ oxidation states, which suggests that reduction and oxidation reactions may effectively act as donor activation and deactivation mechanisms, respectively, for V{sub O}{sup n} in Ta{sub 2}O{sub 5}.

  17. 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 (0x5) 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.

  18. 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…

  19. Experimental tests of garnet peridotite oxygen barometry

    Microsoft Academic Search

    G. Gudmundsson; B. J. Wood

    1995-01-01

    We have performed experiments aimed at testing the calibration of oxygen barometers for the garnet peridotite [garnet (Gt)-olivine\\u000a (Ol)-orthopyroxene (Opx)] phase assemblage. These involved equilibrating a thin layer of garnet sandwiched between layers\\u000a of olivine and orthopyroxene at 1300C and 23–35 kbar for 1–7 days. Oxygen fugacity was controlled (but not buffered) by using\\u000a inner capsules of Fe?Pt alloy or

  20. 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.

  1. An oxygen barometer for rutile–ilmenite assemblages: oxidation state of metasomatic agents in the mantle

    Microsoft Academic Search

    Donggao Zhao; Eric J Essene; Youxue Zhang

    1999-01-01

    Oxygen fugacity has been calculated for rutile–ilmenite assemblages from the reaction 2Fe2O3 (in ilmenite) + 4TiO2 (rutile) = 4FeTiO3 (in ilmenite) + O2. The equation logfO2=22.59?25925\\/T?3.09logT+0.0016535P+48.836P\\/T?4logaIlmFeTiO3+2logaIlmFe2O3+4logaRutTiO2, where T is in kelvin and P is in kbar, was derived from available thermodynamic data. The hypothetical end-member rutile–ilmenite reaction is located between the magnetite–hematite and Ni–NiO (NNO) buffers. The rutile–ilmenite oxygen barometer

  2. A redox profile of the Slave mantle and oxygen fugacity control in the cratonic mantle

    Microsoft Academic Search

    C. McCammon; M. G. Kopylova

    2004-01-01

    The authors report a redox profile based on Mössbauer data of spinel and garnet to a depth of 210 km from mantle xenoliths of the northern (N) and southeastern (SE) Slave craton (northern Canada). The profile transects three depth facies of peridotites that form segments of different bulk composition, represented by spinel peridotite, spinel–garnet peridotite, low-temperature garnet peridotite, high-temperature garnet peridotite,

  3. Electrical Conductivity of Olivine at High Pressure and Under Controlled Oxygen Fugacity

    Microsoft Academic Search

    A. Duba; H. C. Heard; R. N. Schock

    1974-01-01

    It is now generally accepted that the major phase in the earth's upper mantle is olivine with an approximate composi- tion Mgx.sFe0..SiO4 (Fujisawa, 1968). Published values of elec- trical conductivity a of olivine of this composition (either single crystal or polycrystalline) at high temperatures show very poor agreement (Duba and Lilley, 1972). In many in- stances the difference can be

  4. 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.

  5. 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.

  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. 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.

  8. Calculator.

    ERIC Educational Resources Information Center

    Parma City School District, OH.

    Five activities are presented in this student workbook on using the electronic calculator. Following the directions for using the machine, problems are given on multiplying and dividing, finding percentages, calculating the area of assorted polygons, changing fractions to decimals, and finding squares and square roots. (JH)

  9. 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

  10. Scaling of Gene Expression with Transcription-Factor Fugacity

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

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

    Microsoft Academic Search

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

    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

  12. 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 the domain during and after the flood. The chemical emissions rate are estimated based on land use and population for three different classes of contaminants; the classes are representative of contaminants released from agricultural sources, sewage disposal and industrial/commercial emissions. The module for source estimation provides the spatial distribution of the potential emissions rates in the area. Emission rates are forcing input for the third simulation module whenever the pertinent area is inundated. The second module simulates the flood dynamics by using a parabolic approximation of the two dimensional shallow water equation. The model is properly developed in order to utilize simplified initial and boundary conditions, such as flooding points and flooding voulmes or satellite derived DTMs and land use . Thanks to its computational efficiency it is possible to run several simulations in order to adjust initial and boundary conditions, which are partly unknown, to satellite delineation of the flooded areas which are used as constrain for the 2D dynamic simulation. In this way the result is a dynamically consistent flooded map enriched with important information about hydraulic forcing parameters (i.e. hydraulic depths, flow velocities at every temporal step). The third module simulates the two-dimensional spatial distribution of pollutants concentration in all the environmental media. The mass balance equation for the chemicals is here derived in term of chemical fugacity instead the classical molar concentration. The advatage of the fugacity instead of concentration is that, since fugacity is continuous among phase interfaces and concentration is not, it renders the analysis of contaminat transfer between the phases easier. The two dimensional - depth averaged- mass balance equation is solved numerically by a finite volume tecnique over a rectangular regular grid. The model has been applied to the inundation of SHKODRA region in Albania during the January- February 2010. This inundation was produced by two rivers: DRINI and BUNA. The flooded

  13. An experimental study of oxygen transport in dry rocks and related kinetic phenomena

    NASA Astrophysics Data System (ADS)

    Watson, E. Bruce

    1986-12-01

    Several series of experiments were carried out at 1 GPa and 900°-1100° in which grain boundary chemical diffusion of oxygen in dry quartzite and dunite was characterized by use of "indicator mineral" techniques. Most experiments involved mixing a small amount of Fe2O3 with coarse quartz or olivine powder, placing the mixture in an iron container, pressurizing in a piston-cylinder apparatus, and heating rapidly to the desired run temperature. In response to the large gradient in oxygen fugacity resulting from the juxtaposition of iron metal (i.e., the container) with Fe2O3 disseminated through the sample, oxygen transport along quartz or olivine grain boundaries took place, causing reduction of ferric iron in regions of the sample nearest the container (producing wüstite in the dunite experiments and fayalite in those on quartz). The flux of oxygen, and hence the diffusivity, could be calculated from the width of the observed reduction zone. Variations on the method just described included use of CuO rather than Fe2O3 as the "indicator mineral," use of graphite rather than iron as the container, and placement of the Fe2O3 as a single pellet at the center of the dunite or quartzite sample rather than as a dispersed minor phase. For the dispersed-Fe2O3 experiments on dunite at 1000° and 1100°C, the width of the reduced (wüstite-bearing) zone was found to be generally proportional to the square root of run duration, in accordance with a diffusion-controlled transport/reduction process. At 900°, however, this relation does not hold, and the data suggest vapor phase transport of oxygen prior to closure of sample porosity. All experiments on quartzite (900°-1100°) were plagued by the same problem, but in this case, sufficiently long experiment durations eventually resulted in no further measurable oxygen transport, demonstrating that well-annealed quartzite is impermeable to oxygen at the run conditions. The net outcome of the experiments is a bulk grain boundary diffusivity for oxygen in dunite given approximately by D = 106exp (-355,500/RT) (D in cm2/s; R in J/deg mol). Values for quartzite are too low to measure by the techniques attempted. The information can be used to argue that heterogeneities in oxygen fugacity on the scale of centimeters to meters can be maintained indefinitely in fluid-absent, high-grade rocks of the continental crust, but similar features in a fluid-absent mantle would be quickly erased.

  14. Simulation of the Fate and Seasonal Variations of ?-Hexachlorocyclohexane in Lake Chaohu Using a Dynamic Fugacity Model

    PubMed Central

    Kong, Xiang-zhen; He, Wei; Qin, Ning; He, Qi-Shuang; Yang, Bin; Ouyang, Huiling; Wang, Qingmei; Yang, Chen; Jiang, Yujiao; Xu, Fuliu

    2012-01-01

    Fate and seasonal variations of ?-hexachlorocyclohexane (?-HCH) were simulated using a dynamic fugacity model in Lake Chaohu, China. Sensitivity analyses were performed to identify influential parameters and Monte Carlo simulation was conducted to assess model uncertainty. The calculated and measured values of the model were in good agreement except for suspended solids, which might be due to disregarding the plankton in water. The major source of ?-HCH was an input from atmospheric advection, while the major environmental outputs were atmospheric advection and sediment degradation. The net annual input and output of ?-HCH were approximately 0.294?t and 0.412?t, respectively. Sediment was an important sink for ?-HCH. Seasonal patterns in various media were successfully modeled and factors leading to this seasonality were discussed. Sensitivity analysis found that parameters of source and degradation were more important than the other parameters. The sediment was influenced more by various parameters than air and water were. Temperature variation had a greater impact on the dynamics of the model output than other dynamic parameters. Uncertainty analysis showed that the model uncertainty was relatively low but significantly increased in the second half of the simulation period due to the increase in the gas-water diffusion flux variability. PMID:23365527

  15. Predicting PCB concentrations in cow milk: validation of a fugacity model in high-mountain pasture conditions.

    PubMed

    Tremolada, Paolo; Guazzoni, Niccolò; Parolini, Marco; Rossaro, Bruno; Bignazzi, Marta Maria; Binelli, Andrea

    2014-07-15

    A fugacity model reported in the literature was applied to a high-altitude pasture in the Italian Alps. The model takes into account three compartments (digestive tract, blood and fat tissues) in unsteady-state conditions using food as the contamination source. Disregarding biotransformation inside cow tissues, the predicted concentrations of 14 polychlorinated biphenyls (PCBs) in milk were in good agreement with the observed data, especially for congeners known for their resistance to biotransformation (e.g., CB-138 and 153). In contrast, the predicted concentrations were clearly overestimated for congeners with high biotransformation susceptibilities. Therefore data measured in milk and faeces were used to calculate the first-order-biotransformation rate constants in dairy cows. The PCB absorption efficiency observed for pasture conditions was lower than that observed in the cowshed. The final version of the model included biotransformation and observed PCB absorption and was able to predict PCB concentrations in cow milk with mean differences between the predicted and measured data below ± 20% for most congeners. PMID:24802270

  16. Deriving a sea surface climatology of CO2 fugacity in support of air-sea gas flux studies

    NASA Astrophysics Data System (ADS)

    Goddijn-Murphy, L. M.; Woolf, D. K.; Land, P. E.; Shutler, J. D.; Donlon, C.

    2014-07-01

    Climatologies, or long-term averages, of essential climate variables are useful for evaluating models and providing a baseline for studying anomalies. The Surface Ocean Carbon Dioxide (CO2) Atlas (SOCAT) has made millions of global underway sea surface measurements of CO2 publicly available, all in a uniform format and presented as fugacity, fCO2. fCO2 is highly sensitive to temperature and the measurements are only valid for the instantaneous sea surface temperature (SST) that is measured concurrent with the in-water CO2 measurement. To create a climatology of fCO2 data suitable for calculating air-sea CO2 fluxes it is therefore desirable to calculate fCO2 valid for climate quality SST. This paper presents a method for creating such a climatology. We recomputed SOCAT's fCO2 values for their respective measurement month and year using climate quality SST data from satellite Earth observation and then extrapolated the resulting fCO2 values to reference year 2010. The data were then spatially interpolated onto a 1° × 1° grid of the global oceans to produce 12 monthly fCO2 distributions for 2010. The partial pressure of CO2 (pCO2) is also provided for those who prefer to use pCO2. The CO2 concentration difference between ocean and atmosphere is the thermodynamic driving force of the air-sea CO2 flux, and hence the presented fCO2 distributions can be used in air-sea gas flux calculations together with climatologies of other climate variables.

  17. Oxygen and silicon contents of Earth's core from high pressure metal-silicate partitioning experiments

    NASA Astrophysics Data System (ADS)

    Ricolleau, Angele; Fei, Yingwei; Corgne, Alexandre; Siebert, Julien; Badro, James

    2011-10-01

    Oxygen and silicon partitioning between molten metal and silicate melts was measured in samples synthezised in piston-cylinder and multi-anvil presses between 2 and 21 GPa, 2273 and 2873 K, and at oxygen fugacities of 1.5-3.6 log units below the iron-wüstite buffer. Our partitioning data are used together with published data to parameterize the individual effects of pressure, temperature and composition on the partitioning of oxygen and silicon. Results show that the oxygen metal-silicate partition coefficient increases with increasing oxygen fugacity, temperature and pressure, whereas the silicon metal-silicate partition coefficient increases with decreasing oxygen fugacity, increasing temperature and pressure. Silicon and oxygen contents of Earth's core were derived for different core formation models. Considering single-stage core formation at 40 GPa, 3200 K, IW-2, the core would contain 1 to 3.5 wt.% silicon and 0.5 to 2.5 wt.% oxygen. In a continuous core-formation scenario, and depending on the oxidation path, Si core content varies from 1 to 11 wt.%, whereas oxygen content ranges from 0 to 2.5 wt.%. These models show that the oxygen content in the core cannot be significantly higher than 2.5 wt.%. In these compositional models, a range of combined silicon and oxygen concentrations in the core could satisfies the seismologically observed range of outer core density deficits.

  18. Carbon-free and two-dimensional cathode structure based on silicene for lithium-oxygen batteries: A first-principles calculation

    NASA Astrophysics Data System (ADS)

    Hwang, Yubin; Yun, Kyung-Han; Chung, Yong-Chae

    2015-02-01

    The lithium-oxygen (Li-O2) battery is one of the most promising technologies for energy storage due to its extremely high-energy density. However, the design still faces many challenges for practical use including the decomposition of cathodes, which are typically composed of carbon-based materials. In this study, a carbon-free and two-dimensional cathode structure based on silicene is first proposed for Li-O2 batteries using density functional theory calculations. In contrast to graphene, oxygen reduction reactions (ORR) and oxygen evolution reactions (OER) can occur on the pristine form of silicene without any defect sites. In addition, it was found that reactions on silicene strongly correlate with strong adsorptions of the ORR intermediates, which are caused not only by ionic bonding between the oxygen atoms in the ORR intermediates and silicene but also by the structural stabilization of silicene. Theoretical observations demonstrate the great potential of silicene as a carbon-free cathode structure for Li-O2 batteries and provide further insights for designing a new cathode material architecture based on two-dimensional structured materials.

  19. Control of the Water Fugacity Under High Pressures and Temperatures: Applications to the Water Solubility in Olivine

    Microsoft Academic Search

    K. Otsuka; S. Karato

    2009-01-01

    Previous experimental studies have shown significant influence of water on the physical and chemical properties of mantle materials, such as diffusivity, viscosity, and electrical conductivity. Those experiments were, however, conducted either at water-saturated conditions with the excess fluid phases or at water under-saturated conditions without controlling the amount of water. In these cases, the influence of water fugacity can not

  20. The precision of a fugacity-based model for estimating dermal uptake of chemicals from soil

    SciTech Connect

    McKone, T.E.

    1990-10-01

    Uncertainty about the predicted uptake of hydrocarbons from dusts and soils on human skin is addressed using a fugacity model. Methods available for sensitivity and uncertainty analysis are reviewed and assessed. A fugacity-based compartment model for dermal uptake from soil is presented. A major assumption of the uptake model is that soil on human skin behaves as a layer of soil particles mixed with air and water such that a tortuousity model applies. The possibility that soil instead attaches to skin as individual particles introduces uncertainty to the estimates of uptake derived from this model. In order to assess the magnitude of this uncertainty, the model is derived with and without the soil-layer assumption. Using 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and hexachlorobenzene (HCB) as test chemicals, a differential sensitivity analysis is applied to the layer and no-layer models in order to estimate the relative sensitivity of model output (uptake fraction) to all of the input parameters. A Monte Carlo simulation is used to carry out an uncertainty analysis in order to quantify the precision of the dermal-uptake prediction when applied to TCDD and HCB using both the soil-layer and no-soil layer assumptions. The predicted uptake fraction of HCB has an arithmetic-mean value of 0.15 and arithmetic standard deviation of 0.18; the predicted uptake fraction of TCDD has an arithmetic-mean value of 0.30 and arithmetic standard deviation of 0.28. 19 refs., 3 figs., 3 tabs.

  1. 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 be applied to measurements taken elsewhere in the oceans, and of variables other than carbon dioxide.

  2. 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.

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

    Microsoft Academic Search

    Gary Strangman; Maria Angela Franceschini; David A. Boasb

    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

  4. Oxygen and silicon partitioning between molten iron and silicate melts

    NASA Astrophysics Data System (ADS)

    Ricolleau, A.; Fei, Y.; Siebert, J.; Corgne, A.; Badro, J.

    2010-12-01

    The Earth’s core is mainly composed of a Fe-Ni alloy. The core density deficit compared to the density of pure iron requires the presence of light elements in addition to Fe and Ni. Si and O are among the likely candidates. Previous experimental studies have focused on the system Fe-(Mg, Fe)O to interpret the behavior of oxygen in iron melts, (Mg,Fe)O being used as a proxy for the silicate phase. In this study, we investigated directly the partitioning of oxygen and silicon between molten iron and silicate melts. We used 2 starting materials, prepared by mixing Fe and FeO, MgO and SiO2 in different proportions. Experiments were performed in MgO capsules at 2, 7, 14, and 21 GPa at temperatures of 2273, 2573, and 2873 K, using piston cylinder and multi-anvil presses. Recovered samples were analyzed with an electron microprobe. The partition coefficients of oxygen and silicon between metal and silicate were determined as a function of pressure, temperature and oxygen fugacity. The measured data are used with literature data to parameterize thermodynamically the partitioning of oxygen and silicon. The derived relationships reveal significant influence of oxygen fugacity on the partitioning of oxygen and silicon. Silicon partitioning depends more strongly on pressure than temperature, and the inverse is observed for oxygen. if the observed trends are valid at higher pressures, considering continuous core segregation under progressively oxidizing conditions as recently proposed, the core would contain about 8 wt% Si and less than 0.5 wt% O. In this case, Si would be the main contributor to the light element budget in the core. In comparison, for a single-stage scenario at oxygen fugacity of IW-2 and equilibration pressure of 40 GPa, the core would only contain about 2 wt% Si and 1 wt% O.

  5. 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.

  6. 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.

  7. Nature Macmillan Publishers Ltd 1997 of composition, temperature, oxygen fugacity and pressure on their redox states. Contrib. Mineral.

    E-print Network

    Dominey, Peter F.

    of interest can be defined with respect to the observer's head if the position of the eyes in the orbit for the selected part of the body, such as the eye, head or arms1­4 . To achieve this transformation, visual parietal lobe, the ventral intraparietal area (VIP), the activity of visual neurons is modulated by eye

  8. 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

    2015-03-01

    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 ?13CvPDB values of the whole rocks (-23.1 to -25.8 ‰) in the wall rocks suggest a sedimentary organic carbon source. The ?13CvPDB 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 ?13CCO2-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 logfO2 > FMQ + 1 in the magma stage, to logfO2 < FMQ as a consequence of country rocks assimilation-contamination, to logfO2 > 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.

  9. 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).

  10. 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 (

  11. The effect of oxygen fugacity and temperature on solubilities of nickel, cobalt, and molybdenum in silicate melts

    Microsoft Academic Search

    A. Holzheid; A. Borisov; H. Palme

    1994-01-01

    Solubilities of Ni, Co and Mo in silicate melts of anorthite-diopside eutectic composition were determined at reducing conditions, with f O 2 values ranging from 10 -8.6 to 10 -12.6 atm and at temperatures of around 1400°C. In a log (solubility) vs. log ( f O 2 ) diagram, Ni and Co data plot along straight lines with slopes of

  12. 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.

  13. The influence of partial melting on the electrical behavior of crustal rocks: laboratory examinations, model calculations and geological interpretations

    Microsoft Academic Search

    G. M. Partzsch; F. R. Schilling; J. Arndt

    2000-01-01

    The complex electrical impedance of a granulite has been determined over the frequency range 10?1 to 105Hz at temperatures between 600 and 1200°C at normal pressure and different oxygen fugacities in the stability field of magnetite. The impedance spectroscopic (IS) measurements are compared with the results of melting experiments performed under the same experimental conditions and with the same rock

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

    NASA Technical Reports Server (NTRS)

    Williams, R. J.; Mullins, O.

    1981-01-01

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

  15. 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. PMID:25145214

  16. 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. PMID:18267327

  17. 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 structural proposals. Thus it emerges as a useful contributor to the ongoing efforts that aim at establishing correlations between the body of spectroscopic data available for the various S(i) states of the OEC and their actual geometric features. PMID:19639153

  18. 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.

  19. Coulomb interaction in oxygen \\\\textit{p}-shell in LDA+U method and its influence on calculated spectral and magnetic properties of transition metal oxides

    Microsoft Academic Search

    I. A. Nekrasov; M. A. Korotin; V. I. Anisimov

    2000-01-01

    Coulomb interaction between electrons on p-orbitals of oxygen atom in strongly correlated compounds is not negligible, since its value (U_p) has comparable order of magnitude with the value of Coulomb interaction on d-orbitals of transition metal atom (U_d). We investigate the effect of taking into account Coulomb correlations in oxygen p-shell in addition to the correlations in the transition metal

  20. Oxygen Defects in Phosphorene

    NASA Astrophysics Data System (ADS)

    Ziletti, A.; Carvalho, A.; Campbell, D. K.; Coker, D. F.; Castro Neto, A. H.

    2015-01-01

    Surface reactions with oxygen are a fundamental cause of the degradation of phosphorene. Using first-principles calculations, we show that for each oxygen atom adsorbed onto phosphorene there is an energy release of about 2 eV. Although the most stable oxygen adsorbed forms are electrically inactive and lead only to minor distortions of the lattice, there are low energy metastable forms which introduce deep donor and/or acceptor levels in the gap. We also propose a mechanism for phosphorene oxidation involving reactive dangling oxygen atoms and we suggest that dangling oxygen atoms increase the hydrophilicity of phosphorene.

  1. 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 ...

  2. 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 existing indicators of oxidation state for each system, as available. Zircons included this study are from Mount St. Helens (?NNO +1.5 log units; Smith, 1984), the Peach Spring Tuff and Spirit Mountain Batholith (sphene-bearing, silicic, Miocene-aged rocks from the Colorado River Extensional Corridor), Alid Volcano in Eritrea, and rhyolites and granites from Iceland. Median log fO2 for these systems, calculated from the Cerium anomaly in zircons following Trail et al. (2011) using temperatures from Ti-in-zircon thermometry (Ferry and Watson, 2007) are as follows: Alid -12 bars (?NNO +3 log units) at 750 degrees C; Iceland -11 bars (?NNO +3 log units) at 800 degrees C; Mount St. Helens -8.6 bars (?NNO +6 log units) at 750 degrees C; Peach Spring Tuff -3.4 (?NNO +10 log units) at 830 degrees C. While ubiquitous sphene in the Spirit Mountain granites suggest relatively high fO2, calculations based on the cerium anomaly in zircon suggest median log fO2 of >0 at 770 degrees C, which is certainly erroneous. While median values for our natural zircons are, for the most part, above expected fugacities for each system when compared with other indicators, and extreme values for each system are almost certainly erroneous, many are within expected values for terrestrial magmas and they vary relative to one another as might be expected given the magma types and tectonic settings.

  3. Supplemental Oxygen (Oxygen Therapy)

    MedlinePLUS

    ... gas and is non-flammable, however, it supports combustion. Materials burn more readily in an oxygen-enriched ... avoid using lotions or creams containing petroleum. The combustion of flammable products containing petroleum can also be ...

  4. Non-Maxwellian velocity distribution functions associated with steep temperature gradients in the solar transition region. Paper 2: The effect of non-Maxwellian electron distribution functions on ionization equilibrium calculations for carbon, nitrogen and oxygen

    NASA Technical Reports Server (NTRS)

    Roussel-Dupre, R.

    1979-01-01

    Non-Maxwellian electron velocity distribution functions, previously computed for Dupree's model of the solar transition region are used to calculate ionization rates for ions of carbon, nitrogen, and oxygen. Ionization equilibrium populations for these ions are then computed and compared with similar calculations assuming Maxwellian distribution functions for the electrons. The results show that the ion populations change (compared to the values computed with a Maxwellian) in some cases by several orders of magnitude depending on the ion and its temperature of formation.

  5. Coulomb interaction in oxygen \\\\textit{p}-shell in LDA+U method and its influence on calculated spectral and magnetic properties of transition metal oxides

    Microsoft Academic Search

    I. A. Nekrasov; M. A. Korotin; V. I. Anisimov

    2000-01-01

    Coulomb interaction between electrons on p-orbitals of oxygen atom in\\u000astrongly correlated compounds is not negligible, since its value (U_p) has\\u000acomparable order of magnitude with the value of Coulomb interaction on\\u000ad-orbitals of transition metal atom (U_d). We investigate the effect of taking\\u000ainto account Coulomb correlations in oxygen p-shell in addition to the\\u000acorrelations in the transition metal

  6. Thermodynamic properties of oxygen

    SciTech Connect

    Sychev, V.V.; Vasserman, A.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymarny, V.A.

    1987-01-01

    Even after almost a century of experimental analysis, thermodynamic property tables for oxygen were often based on limited data. However, this new volume incorporates new information about density and isochoric specific heat into an unmatched, reliable set of tables. Temperatures and pressures covered range from the triple point to 1500 K, and 0.1 to 100 MPa, respectively. This accurate information describes oxygen in both liquid and gaseous phases. This volume contains: experimental data on thermodynamic properties of oxygen; methods of deriving the equation of state and calculating thermodynamic tables; the equation of state and evaluation of computed thermodynamic functions relative to experimental data; these of the thermodynamic properties of oxygen.

  7. 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.

  8. Calculation of the relative metastabilities of proteins using the CHNOSZ software package

    PubMed Central

    Dick, Jeffrey M

    2008-01-01

    Background Proteins of various compositions are required by organisms inhabiting different environments. The energetic demands for protein formation are a function of the compositions of proteins as well as geochemical variables including temperature, pressure, oxygen fugacity and pH. The purpose of this study was to explore the dependence of metastable equilibrium states of protein systems on changes in the geochemical variables. Results A software package called CHNOSZ implementing the revised Helgeson-Kirkham-Flowers (HKF) equations of state and group additivity for ionized unfolded aqueous proteins was developed. The program can be used to calculate standard molal Gibbs energies and other thermodynamic properties of reactions and to make chemical speciation and predominance diagrams that represent the metastable equilibrium distributions of proteins. The approach takes account of the chemical affinities of reactions in open systems characterized by the chemical potentials of basis species. The thermodynamic database included with the package permits application of the software to mineral and other inorganic systems as well as systems of proteins or other biomolecules. Conclusion Metastable equilibrium activity diagrams were generated for model cell-surface proteins from archaea and bacteria adapted to growth in environments that differ in temperature and chemical conditions. The predicted metastable equilibrium distributions of the proteins can be compared with the optimal growth temperatures of the organisms and with geochemical variables. The results suggest that a thermodynamic assessment of protein metastability may be useful for integrating bio- and geochemical observations. PMID:18834534

  9. Angular dependence of core hole screening in LiCoO2: A DFT+U calculation of the oxygen and cobalt K-edge x-ray absorption spectra

    E-print Network

    be direclty seen from Fig. 1 at the Co K-edge in LiCoO2. HERFD-XAS is based on a two photons process (photon-electron interactions in the final state.13 However, in the case of Co K-edge in LiCoO2, it has been shown that HERFD-XASAngular dependence of core hole screening in LiCoO2: A DFT+U calculation of the oxygen and cobalt K-edge

  10. First principles calculation on the magnetic, optical properties and oxygen vacancy effect of CexY3-xFe5O12

    NASA Astrophysics Data System (ADS)

    Liang, Xiao; Xie, Jianliang; Deng, Longjiang; Bi, Lei

    2015-02-01

    We report a first principles study on the magnetic and optical properties of Ce substituted yttrium iron garnet (CexY3-xFe5O12) (Ce:YIG) (x = 0.125, 0.25, 0.5, and 1.0). Using density functional theory with Hubbard-U corrections, we demonstrate that Ce3+-Fe3+(tetrahedral) charge transfer is the dominating mechanism of enhanced near infrared absorption in Ce:YIG. In particular, oxygen vacancies are found to be able to stabilize Ce3+ from converting to Ce4+, at the same time reduce two neighboring Fe3+ to Fe2+ which occupy both the octahedral and tetrahedral sites. The formation enthalpy of Ce4+-Fe2+ state is strongly dependent on the distance from the Ce ion to the oxygen vacancy, which is closely related to the local lattice distortion around the Ce ion. This result provides theoretical insight for developing high figure of merit magneto-optical materials for nonreciprocal photonic applications.

  11. Use of fugacity model to analyze temperature-dependent removal of micro-contaminants in sewage treatment plants.

    PubMed

    Thompson, Kelly; Zhang, Jianying; Zhang, Chunlong

    2011-08-01

    Effluents from sewage treatment plants (STPs) are known to contain residual micro-contaminants including endocrine disrupting chemicals (EDCs) despite the utilization of various removal processes. Temperature alters the efficacy of removal processes; however, experimental measurements of EDC removal at various temperatures are limited. Extrapolation of EDC behavior over a wide temperature range is possible using available physicochemical property data followed by the correction of temperature dependency. A level II fugacity-based STP model was employed by inputting parameters obtained from the literature and estimated by the US EPA's Estimations Programs Interface (EPI) including EPI's BIOWIN for temperature-dependent biodegradation half-lives. EDC removals in a three-stage activated sludge system were modeled under various temperatures and hydraulic retention times (HRTs) for representative compounds of various properties. Sensitivity analysis indicates that temperature plays a significant role in the model outcomes. Increasing temperature considerably enhances the removal of ?-estradiol, ethinyestradiol, bisphenol, phenol, and tetrachloroethylene, but not testosterone with the highest biodegradation rate. The shortcomings of BIOWIN were mitigated by the correction of highly temperature-dependent biodegradation rates using the Arrhenius equation. The model predicts well the effects of operating temperature and HRTs on the removal via volatilization, adsorption, and biodegradation. The model also reveals that an impractically long HRT is needed to achieve a high EDC removal. The STP model along with temperature corrections is able to provide some useful insight into the different patterns of STP performance, and useful operational considerations relevant to EDC removal at winter low temperatures. PMID:21600629

  12. Kinetic coupling and hydrogen surface fugacities in heterogeneous catalysis: I. Alkane reactions on Te/NaX, H-ZSM5, and Ga/H-ZSM5

    SciTech Connect

    Iglesia, E.; Baumgartner, J.E.; Price, G.L. (Exxon Research and Engineering Corp., Annandale, NJ (United States))

    1992-04-01

    Hydrogen removal occurs by recombinative desorption and by hydrogen transfer during dehydrogenation steps required for alkane and cycloalkane conversion on Te/NaX, H-ZSM5, and Ga/H-ZSM5 catalysts. Recombinative desorption limits the rate of n-heptane and methylcyclohexane aromatization on Te/NaX and prevents equilibrium between gas-phase H[sub 2] and H-adatoms formed in intermediate dehydrogenation steps. The resulting high surface hydrogen fugacities lead to low steady-state concentrations of required unsaturated intermediates. Te ions catalyze rate-limiting hydrogen desorption steps during alkane reactions on Te/NaX. On H-ZSM5, hydrogen removal limits the rate of propane conversion to aromatics. Hydrogen adatoms are removed predominantly by reactions with coadsorbed hydrocarbon fragments, leading to high cracking selectivity. Ga ions introduce a recombinative desorption function that partially relieves the resulting high hydrogen surface fugacities and allows dehydrogenation steps to occur without concurrent cracking. Thus, Ga ions increase aromatics selectivity by providing a porthole for the removal of hydrogen adatoms as dihydrogen. The authors propose that rate-limiting hydrogen desorption steps, and the high surface hydrogen fugacities that result, control the rate and selectivity of dehydrogenation and related reactions on many nonmetal surfaces.

  13. 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.

  14. 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.

  15. Oxygen analyzer

    DOEpatents

    Benner, William H. (Danville, CA)

    1986-01-01

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

  16. Atmospheric Oxygen

    NSDL National Science Digital Library

    2003-09-26

    In this feature, adapted from Interactive NOVA: Earth, students explore the relationship between oxygen concentration and the well-being of various organisms by simulating a change in oxygen levels and observing what happens.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  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. Fe-Mg interdiffusion in single crystal olivine at very high pressure and controlled oxygen fugacity: technological advances and initial data at 7 GPa

    Microsoft Academic Search

    Yves Bertran-Alvarez; Olivier Jaoul; Robert C. Liebermann

    1992-01-01

    The interdiffusion of iron and magnesium in natural single crystals of San Carlos olivine (Fo90) has been determined using a 2000 ton uniaxial split-sphere apparatus (USSA-2000) and Rutherford back-scattering spectrometry (RBS). Advances in the microanalysis technique made it possible to perform high-pressure experiments for short-duration runs at low temperatures in a controlled chemical and mechanical environment. Olivine crystals were coated

  4. Fe?Mg interdiffusion in single crystal olivine at very high pressure and controlled oxygen fugacity: technological advances and initial data at 7 GPa

    NASA Astrophysics Data System (ADS)

    Bertran-Alvarez, Yves; Jaoul, Olivier; Liebermann, Robert C.

    1992-02-01

    The interdiffusion of iron and magnesium in natural single crystals of San Carlos olivine (Fo 90) has been determined using a 2000 ton uniaxial split-sphere apparatus (USSA-2000) and Rutherford back-scattering spectrometry (RBS). Advances in the microanalysis technique made it possible to perform high-pressure experiments for short-duration runs at low temperatures in a controlled chemical and mechanical environment. Olivine crystals were coated with a thin film of fayalite, inserted in an Fe capsule and placed inside an 18 mm pyrophyllite octahedral cell assembly. After experiments at 7 GPa and 900°C for 6 h at pO 2 ? 10 -14 bar, the specimens were recovered with very few fractures and chemically unaltered. Analysis of RBS spectra from these crystals yields a value of DFe?Mg = 10 -13.7cm2s-1. Comparison of this value with previous data at atmospheric pressure suggests that the activation volume for Fe?Mg interdiffusion is V Fe?Mg? ? 2.2 ± 0.9 cm 3 mol -1 which, if proven correct, has important implications for electrical conductivity and creep in the upper mantle.

  5. 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, ...

  6. 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.

  7. 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.

  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. PMID:24947127

  10. Oxygen Therapy

    MedlinePLUS

    ... need oxygen therapy by testing the presence of gases in your blood. This test is called an ... is already in the air and removing other gases. The concentrator is powered by electricity. What is ...

  11. Behavior of oxygen partitioning between iron metal and silicate or oxide up to 21 GPa and 2600 degree C

    NASA Astrophysics Data System (ADS)

    Ricolleau, A.; Fei, Y.; Badro, J.

    2009-12-01

    The Earth’s core is mainly composed of a Fe-Ni alloy. The core density deficit, compared to the density of pure iron, requires the presence of about 10 % of light elements. Si and O are among the likely candidates for light elements in the core. Previous studies have focused on the system Fe-(Mg, Fe)O to interpret the behavior of oxygen in iron melts. In this study, we report the behavior of oxygen partitioning between metal and silicate/oxide melts. We used 4 starting materials, prepared by mixing Fe and FeO, MgO and SiO2 in different proportions. Experiments were performed in MgO capsules at 2, 7, 14, and 21 GPa at temperatures of 2273, 2573, and 2873 K, using a piston cylinder apparatus and multi-anvil press. Recovered samples were analyzed with an electron microprobe. As observed by Asahara et al. (Earth Planet. Sci. Lett., 257, 435-449, 2007), the oxygen distribution coefficient, KD (defined as KD= (XFeXO)/XFeO, where XFe and XO are the mole fractions of Fe and O in liquid metal and XFeO is the mole fraction of FeO in silicate) varies very little with pressure, but is strongly dependant on temperature, within our experimental pressure range. Unlike some previous studies, the oxygen distribution coefficient shows a dependence on oxygen fugacity. Thus, the partition coefficient of oxygen in liquid metal alloy was studied as a function of pressure, temperature, oxygen fugacity and silicate content. One of the possible scenarios of Earth accretion considers a shallow magma ocean which leads to a core containing less than 1 wt% oxygen. Extrapolation to higher pressure is subject to debate because some studies showed that the behavior of oxygen in metal melts changes above 25 GPa.

  12. Oxygen transfer in foods using oxygen luminescence sensors: Influence of oxygen partial pressure and food nature and composition

    Microsoft Academic Search

    C. Pénicaud; S. Guilbert; S. Peyron; N. Gontard; V. Guillard

    2010-01-01

    A rapid and easy to handle (on-line monitoring) method to achieve oxygen sorption kinetics was developed and tested on a large range of food products. Measurements were performed using luminescence sensors placed into of a thin layer of food material exposed to increasing oxygen contents in the atmosphere. From oxygen sorption kinetics diffusivity values could be calculated using a mathematical

  13. Clinical applicability of the substitution of mixed venous oxygen saturation with central venous oxygen saturation

    Microsoft Academic Search

    Simru Turnao?lu; Mehmet Tu?rul; Emre Çamci; Nahit Çakar; Özkan Akinci

    2001-01-01

    Objective: To examine the clinical applicability of substituting central venous oxygen saturation (ScvO2) for mixed venous oxygen saturation (SmvO2) in monitoring global tissue oxygenation. Design: Prospective clinical investigation. Setting: University hospital. Participants: Seventy-three adult patients. Interventions: Venous oxygen saturation was recorded, and oxygen saturation difference between SmvO2 and ScvO2 (?Smvcv) was calculated in 2 groups of patients (group I, sepsis

  14. 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

  15. Percentage of Oxygen in the Air

    NSDL National Science Digital Library

    2011-08-20

    In this activity, learners calculate the percentage of oxygen in the atmosphere by using steel wool's ability to rust. Learners measure the volume of a test tube with a small amount of steel wool at the bottom before and after 2 days of rusting. They use this data to calculate the percent of oxygen in the air and average class data.

  16. Oxygen safety

    MedlinePLUS

    ... Products that are safe include: Aloe vera Water-based products, such as K-Y Jelly Avoid tripping over oxygen tubing. Try taping the tubing to the back of your shirt. Teach children not to get tangled in the tubing.

  17. Formation and migration of oxygen vacancies in La(1-x)Sr(x)Co(1-y)Fe(y)O(3-?) perovskites: insight from ab initio calculations and comparison with Ba(1-x)Sr(x)Co(1-y)Fe(y)O(3-?).

    PubMed

    Mastrikov, Yuri A; Merkle, Rotraut; Kotomin, Eugene A; Kuklja, Maija M; Maier, Joachim

    2013-01-21

    The formation and migration of oxygen vacancies in the series of (La,Sr)(Co,Fe)O(3-?) perovskites, which can be used as mixed conducting SOFC cathode materials and oxygen permeation membranes, are explored in detail by means of first principles density functional calculations. Structure distortions, charge redistributions and transition state energies during the oxygen ion migration are obtained and analyzed. Both the overall chemical composition and vacancy formation energy are found to have only a small impact on the migration barrier; it is rather the local cation configuration which affects the barrier. The electron charge transfer from the migrating O ion towards the transition metal ion in the transition state is much smaller in (La,Sr)(Co,Fe)O(3-?) compared to (Ba,Sr)(Co,Fe)O(3-?) perovskites where such a charge transfer makes a significant contribution to the low migration barriers observed (in particular for high Ba and Co content). PMID:23202751

  18. Thermodynamic properties of oxygen

    SciTech Connect

    Sychen, V.V.; Vassekman, A.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymakny, V.A.

    1987-01-01

    In this monograph the authors analyze published experimental data on the thermodynamic properties of oxygen, give short descriptions of the methods of construction of the equation of state and of calculation of the tables, provide basic computational relations, and compare the calculated values of quantities with previously published experimental and tabulated data. The use of the authors' method of statistical treatment of many equations of state, equivalent in descriptive precision to the initial information, allowed an increase in the reliability of calculated values of caloric quantities and to evaluate their error. The tables show the values of density, compressibility, enthalpy, entropy, isochoric and isobaric specific heat, speed of sound and many other necessary practical thermodynamic functions for the liquid and gaseous phases and on the solidification and saturation curves in the temperature interval from the triple point to 1500 K and pressures between 0.1 and 100 MPa.

  19. On the physical and biogeochemical processes driving the high frequency variability of CO2 fugacity at 6°S, 10°W: Potential role of the internal waves

    NASA Astrophysics Data System (ADS)

    Parard, Gaëlle; Boutin, J.; Cuypers, Y.; Bouruet-Aubertot, P.; Caniaux, G.

    2014-12-01

    The availability of nutrients in the mixed layer is the main limitation to organic carbon biological production in the tropical regions. In this paper, we investigate the potential role of internal waves at promoting the development of biological activity on a PIRATA mooring at 6°S, 10°W. This mooring is located above the Mid-Atlantic Ridge where we observe strong internal waves. Using a one-dimensional physical and biogeochemical coupled model, we simulate dissolved inorganic carbon (DIC). Providing the influence of vertical advection and turbulent diapycnal diffusivity are (it is vertical advection + turbulent dipycnal mixing) accounted for, we find that this model provides a good fit with observed in situ CO2 fugacity (fCO2). Main effect of internal waves is to rapidly increase the DIC, thus the fCO2 and the nutrients in the mixed layer. The latter induce progressive development of biological activity leading to gradual DIC decrease. Our study highlights the importance of correctly taking into account the effect of internal waves in tropical regions.

  20. High pressure experimental calibration of the olivine-orthopyroxene-spinel oxygen geobarometer: implications for the oxidation state of the upper mantle

    Microsoft Academic Search

    C. Ballhaus; R. F. Berry; D. H. Green

    1991-01-01

    Synthetic spinel harzburgite and lherzolite assemblages were equilibrated between 1040 and 1300 C and 0.3 to 2.7 GPa, under\\u000a controlled oxygen fugacity (f\\u000a O\\u000a 2). f\\u000a O\\u000a 2 was buffered with conventional and open double-capsule techniques, using the Fe?FeO, WC-WO2-C, Ni?NiO, and Fe3O4?Fe2O3 buffers, and graphite, olivine, and PdAg alloys as sample containers. Experiments were carried out in a piston-cylinder

  1. Carbon distribution and fluxes during the SERIES iron fertilization experiment with special reference to the fugacity of carbon dioxide (fCO 2)

    NASA Astrophysics Data System (ADS)

    Wong, Chi Shing; Timothy, David A.; Law, Cliff S.; Nojiri, Yukihiro; Xie, Liusen; Wong, Shau-King Emmy; Page, John S.

    2006-10-01

    Surface seawater fugacity of carbon dioxide (fCO 2) was measured during the Subarctic Ecosystem Response to Iron Enrichment Study (SERIES), July 9-August 5, 2002. Three ships sampled the iron-fertilized waters near Ocean Station P (50°N, 145°W): the Canadian CCGS J.P. Tully (July 9-23, 2002), the chartered Mexican M/V El Puma (July 9-28, 2002), and the Japanese fisheries research ship M/V Kaiyo Maru (July 24-August 5, 2002). Data used here are from the CCGS J.P. Tully and the M/V Kaiyo Maru. From the onset of the experiment to the peak of the iron-induced diatom bloom on day 19, sea-surface fCO 2 decreased from 350 to 265 ?atm and average DIC concentration in the upper 30 m decreased from 2030 to 1990 ?mol kg -1. Changes in fCO 2 in and near the iron patch as observed from the CCGS J.P. Tully and later from the M/V Kaiyo Maru were used to estimate CO 2 drawdown and air-sea fluxes, and in generating a carbon budget during the growth phase (days 3-19) of the experiment. Without considering patch dilution, sources of dissolved inorganic carbon to the patch (1.6±0.25 mol m -2) were nearly double the sum (0.87±0.34 mol m -2) of the sinks: accumulations of dissolved organic and particulate carbon, and the flux of particulate carbon to sediment traps below the patch. However, the budget is balanced after considerations of the effects of patch expansion on property concentrations within the patch. A comparison with other iron fertilization experiments from 1995 to present was made to assess the CO 2 drawdown values.

  2. Dissolved Oxygen and Biochemical Oxygen Demand

    NSDL National Science Digital Library

    This Environmental Protection Agency (EPA) website provides general information about dissolved oxygen, including what it is, sampling and equipment considerations, and sampling and analysis protocols. The site also features a chart of dissolved oxygen solubility as a function of temperature.

  3. Living with Oxygen Therapy

    MedlinePLUS

    ... page from the NHLBI on Twitter. Living With Oxygen Therapy Oxygen therapy helps many people function better and be ... chronic obstructive pulmonary disease) Although you may need oxygen therapy continuously or for long periods, it doesn' ...

  4. 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 ...

  5. 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 Peng-Robinson equations are readily available in the literature. The required equations have been implemented in PHREEQC, version 3, and the parameters for calculating the partial molar volumes and fugacity coefficients have been added to the databases that are distributed with PHREEQC. The ease of use and power of the formulation are illustrated by calculating the solubility of CO2 at high pressures and temperatures, and comparing with well-known examples from the geochemical literature. The equations and parameterizations are suitable for wide application in hydrogeochemical systems, especially in the field of carbon capture and storage.

  6. Electron-impact excitation of neutral oxygen

    E-print Network

    P. S. Barklem

    2006-09-25

    Aims: To calculate transition rates from ground and excited states in neutral oxygen atoms due to electron collisions for non-LTE modelling of oxygen in late-type stellar atmospheres, thus enabling reliable interpretation of oxygen lines in stellar spectra. Methods: A 38-state R-matrix calculation in LS-coupling has been performed. Basis orbitals from the literature (Thomas et al.) are adopted, and a large set of configurations are included to obtain good representations of the target wavefunctions. Rate coefficients are calculated by averaging over a Maxwellian velocity distribution. Results: Estimates for the cross sections and rate coefficients are presented for transitions between the seven lowest LS states of neutral oxygen. The cross sections for excitation from the ground state compare well with existing experimental and recent theoretical results.

  7. A source of atomic oxygen for a chemical CO laser

    Microsoft Academic Search

    T. V. Bystrova; Iu. L. Chizhov

    1985-01-01

    A supersonic chemical CO laser employing a CS2\\/O2 mixture is proposed in which the equilibrium products of the combustion of sulfur in oxygen are used as a source of atomic oxygen. Theoretical calculations are presented which show that supersonic flows containing about 15 percent of oxygen atoms can be generated by this method over a wide range of pressures and

  8. Interactions of Oxygen and Hydrogen on Pd(111) surface

    E-print Network

    Geddes, Cameron Guy Robinson

    ×2) to a (3×3)R30o structure. In addition to this transformation, hydrogen enhances the mobility of oxygen of hydrogen, in agreement with the experimentally observed enhancement of oxygen mobility. The calculationsInteractions of Oxygen and Hydrogen on Pd(111) surface D. O. Demchenko1 , G. M. Sacha2 , M

  9. Gravity Calculator

    NSDL National Science Digital Library

    Brendan Cannell, Ronnie Johnson, The Shodor Education Foundation, Inc.

    The gravity calculator calculates the gravitational force between two masses. Also included is a visualization of the typical measurement of gravitational force (weight) in different environments (stationary and free fall).

  10. Oxygen Transport Ceramic Membranes

    SciTech Connect

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

    2005-02-01

    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 under air separation mode (small gradient) were completed on the membrane of LSCrF-2828 at 900 C. Low pO{sub 2} atmospheres based on with CO-CO{sub 2} mixtures have also been admitted to the delivery side of the LSCrF-2828 membrane to produce the gradients which exist under syngas generation conditions. The CO-CO{sub 2} mixtures have normal isotopic {sup 18}O abundances. The evolution of {sup 18}O on the delivery side in these experiments after an {sup 18}O pulse on the air side reveals a wealth of information about the oxygen transport processes.

  11. 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. (Rutgers Univ.); (UofC); (Mount Holyoke); (Univ. of New Mexico)

    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).

  12. Bayesian Calculator

    NSDL National Science Digital Library

    Birnbaum, Michael H.

    This page, created by Michael H. Birnbaum of Fullerton University, uses Bayes' Theorem to calculate the probability of a hypothesis given a datum. An example about cancer is given to help users understand Bayes' Theorem and the calculator. This page is a great representation of conditional probability. Detailed instructions are provided on proper use of the calculator.

  13. 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.

  14. Oxygen Therapy for Children

    MedlinePLUS

    Why do some children need oxygen therapy? Oxygen is a basic need for all humans. The air we breathe contains about 21 percent oxygen at sea level. ... How do I know if my child needs oxygen? A healthcare provider will figure out if your ...

  15. Dissolved Oxygen Protocol

    NSDL National Science Digital Library

    The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

    2003-08-01

    The purpose of this resource is to measure the amount of oxygen dissolved in water. Students use a dissolved oxygen kit or meter to measure the dissolved oxygen in the water at their hydrology site. The exact procedure depends on the instructions in the dissolved oxygen kit or meter used. The meter requires calibration before use.

  16. Wildlife monitoring, modeling, and fugacity

    SciTech Connect

    Clark, T.; Clark, K.; Paterson, S.; Mackay, D.; Norstrom, R.J. (Univ. of Toronto, Ontario (Canada))

    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.

  17. The Universal Oxygen Connector.

    PubMed

    Lauer, Mark A; Gombkoto, Rebecca L M

    2006-02-01

    The purpose of this article is to describe the benefits of using the Universal Oxygen Connector. Until now, an oxygen hose was only able to connect to a 22-mm fitting, such as those found on humidifiers used in the recovery room, and oxygen tubing was only able to connect to a Christmas tree type adapter. The Universal Oxygen Connector, manufactured and sold by International Medical, Inc (Burnsville, Minn), was developed to allow the practitioner to attach either a 22-mm oxygen hose, oxygen tubing, or a 15-mm oxygen adapter to the same connector. Patients benefit from the administration of supplemental oxygen in the perioperative period. Supplemental oxygen has been shown to decrease postoperative hypoxemia, infection, and in some cases, nausea and vomiting. As such, oxygen should be administered during transport from the operating room to the recovery room, in the recovery room, and at times during transport to the patient room and in the patient room. Oxygen also should be administered whenever a patient receiving oxygen is transported. Use of the Universal Oxygen Connector decreases material waste, decreases hospital costs, saves time and effort and, most importantly, promotes patient safety by providing a versatile system for oxygen delivery. PMID:16483065

  18. 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.

  19. Solid state oxygen sensor

    DOEpatents

    Garzon, Fernando H. (Sante Fe, NM); Chung, Brandon W. (Los Alamos, NM); Raistrick, Ian D. (Los Alamos, NM); Brosha, Eric L. (Los Alamos, NM)

    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.

  20. Living Without Oxygen: Oxygen Tolerance in Bacteria

    NSDL National Science Digital Library

    Sharon Harris

    This activity focuses on chemical processes, such as nitrogen fixation and denitrification, which are carried out by bacteria. Often the efficacy of these processes is determined by the amount of oxygen present in the environment in which the bacteria live. Much of the time, these processes are carried out by facultatively anaerobic bacteria in the suboxic region of lakes, oceans, sediments, and leaf litter. Students will discover whether facultatively anaerobic photoautotrophs share the same tolerance for oxygen, how differences in oxygen tolerance can be tested, and of what significance the tolerance for oxygen is in the nitrogen cycle. They will practice aseptic technique, monitor the growth of bacterial cultures, display their results graphically, and propose environmental problems associated with the oxygen tolerance of nitrogen fixers and denitifiers.

  1. 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.

  2. Oxygen adsorption on graphite and nanotubes

    Microsoft Academic Search

    P. Giannozzi; R. Car; G. Scoles

    2003-01-01

    We study the binding of molecular oxygen to a graphene sheet and to a (8,0) single walled carbon nanotube, by means of spin-unrestricted density-functional calculations. We find that triplet oxygen retains its spin-polarized state when interacting with graphene or the nanotube. This leads to the formation of a weak bond with essentially no charge transfer between the molecule and the

  3. Thermographic observation of hydrocarbon oxygen explosions

    SciTech Connect

    Abney, L.D.; Kelly, M.D.; Mohler, J.H.

    1985-01-01

    Balloons containing methane-oxygen mixtures were detonated to simulate ordinance fireballs. To establish fireball characteristics, analyses were required of reacting temperatures, thermal profiles, and mixing patterns of the methane-oxygen products with the atmosphere. Infrared videothermography measured and recorded the detonation and gas cloud mixing. Image digitization and in-band energy calculations were done to compare reaction parameters for different balloon tests.

  4. Using oxygen at home

    MedlinePLUS

    Because of your sickness, you may need to use oxygen to help you breathe. You will need to know how to use and ... the right amount. Take good care of your teeth and gums. Keep your oxygen far away from ...

  5. MEMS Calculator

    National Institute of Standards and Technology Data Gateway

    SRD 166 MEMS Calculator (Web, free access)   This MEMS Calculator determines the following thin film properties from data taken with an optical interferometer or comparable instrument: a) residual strain from fixed-fixed beams, b) strain gradient from cantilevers, c) step heights or thicknesses from step-height test structures, and d) in-plane lengths or deflections. Then, residual stress and stress gradient calculations can be made after an optical vibrometer or comparable instrument is used to obtain Young's modulus from resonating cantilevers or fixed-fixed beams. In addition, wafer bond strength is determined from micro-chevron test structures using a material test machine.

  6. 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 channels to generate oxygen gradients in a device, and electrolytic reactions to produce oxygen directly on chip. PMID:25251498

  7. 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.

  8. Dependence of tissue oxygen on oxygen delivery.

    PubMed

    Slate, R K; Ryan, M; Bongard, F S

    1996-02-15

    The viability of tissue flaps depends on adequate blood flow and oxygenation. To help ensure oxygen delivery, increased inspired oxygen is often provided. This study uses a porcine model to measure tissue oxygen (TPO2) in a muscle flap, in response to varying levels of inspired oxygen concentration (FiO2). Six swine underwent the creation of a latissimus dorsi island flap. An ultrasonic flow probe was used to monitor afferent flow through the thoracodorsal artery, and a 20-ga fluorescence-quenching optode was employed to monitor TPO2. Additional optodes were inserted in muscle of an ipsilateral hindlimb, and in the terminal ileum. Inspired oxygen concentration was varied from 15 to 100%, and oxygen delivery variables measured. Analysis of variance and multiple linear regression were used to determine which variables had the greatest effect on TPO2. All three sites varied directly with inspired oxygen concentration. Flap TPO2 had a strong dependence on FiO2 and local oxygen delivery (r2 = 0.54). PaO2 and hemoglobin were the most significant determinants of ileal submucosal TPO2 (r2 = 0.65). A correlation between average submucosal and flap TPO2 was observed (r > 0.9, P < 0.05). We conclude that (1) muscle flap and bowel TPO2 vary directly with inspired FiO2, (2) changes in ileal submucosal TPO2 correlate with those observed in muscle, and (3) monitoring of readily accessible muscle TPO2 merits further investigation to evaluate the status of TPO2 in critical visceral beds. PMID:8769967

  9. Medical Oxygen Safety

    MedlinePLUS

    ... to the air a patient uses to breath. Fire needs oxygen to burn. If a fire should start in an oxygen-enriched area, the ... Homes where medical oxygen is used need specific fire safety rules to keep people safe from fire ...

  10. Oxygen gas permselective membrane

    SciTech Connect

    Takamura, T.; Imai, A.; SUzuki, N.

    1984-11-20

    There is disclosed an oxygen gas permselective membrane comprising a film of a water-containable or wettable metallic oxide. The oxygen gas permselective membrane according to this invention, though being very thin, does not allow water vapor and carbon dioxide gas in air to permeate therethrough and has a great function for allowing oxygen gas to selectively permeate therethrough.

  11. 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.

  12. Martindale Calculators

    NSDL National Science Digital Library

    Martindale Calculators is a Web-based tool collection that contains over 19,000 online calculators created by over "3,450" very "creative" individuals, businesses and â??tax supported entities world wide.â? The collection is organized by the following topics: mathematics; statistics; science A-Z; chemistry; physics, astrophysics and astronomy; engineering A-Z; and electrical engineering, computer engineering, & computer science. Each section includes a wealth of websites to explore, all related to mathematical calculations, mostly course materials and articles. Another section lists online calculators relevant for various industries, such as aviation, cosmetics, insurance, and library science. The list is organized alphabetically and creatively stretches the meaning of â??calculatorâ? to include such things as name translators and databases on animal breeds.

  13. Calculating machines

    NSDL National Science Digital Library

    This website created by Erez Kaplan "deals mainly with the mechanical calculating machines from a collector's point of view." Included here is an historical review of calculating machines, along with Kaplan's attempt to classify the machines, a collection of old advertisements for the machines, and a brief history of calculating. The latest feature is a Java applet that lets you operate an 1885 Felt adding machine to give you a sense of the way it was used. The photos and descriptions provide insight on other gadgets such as the Pocket Cash Registers used by "the sophisticated man or woman of 1900 who had everything." The Reference section provides some resources for further reading, including numerous other personal calculator collectors sites and museums.

  14. 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.

  15. 42 CFR 414.226 - Oxygen and oxygen equipment.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Health 3 2012-10-01 2012-10-01 false Oxygen and oxygen equipment. 414.226 Section 414.226 Public...Equipment and Prosthetic and Orthotic Devices § 414.226 Oxygen and oxygen equipment. (a) Payment rules...

  16. 42 CFR 414.226 - Oxygen and oxygen equipment.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Health 3 2014-10-01 2014-10-01 false Oxygen and oxygen equipment. 414.226 Section 414.226 Public...Orthotic Devices, and Surgical Dressings § 414.226 Oxygen and oxygen equipment. (a) Payment rules...

  17. 42 CFR 414.226 - Oxygen and oxygen equipment.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Health 3 2013-10-01 2013-10-01 false Oxygen and oxygen equipment. 414.226 Section 414.226 Public...Equipment and Prosthetic and Orthotic Devices § 414.226 Oxygen and oxygen equipment. (a) Payment rules...

  18. 42 CFR 414.226 - Oxygen and oxygen equipment.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Health 3 2010-10-01 2010-10-01 false Oxygen and oxygen equipment. 414.226 Section 414.226 Public...Equipment and Prosthetic and Orthotic Devices § 414.226 Oxygen and oxygen equipment. (a) Payment rules...

  19. Dissolved Oxygen Activity

    NSDL National Science Digital Library

    Steve Gordon

    One of the most important measures of the health of the stream is the level of dissolved oxygen (DO) in the water. Oxygen (O2) dissolves in water through the mixing of the water surface with the atmosphere. The oxygen is used by fish and other animals in the water to "breath" through their gills or other respiratory systems and by plants. If the levels fall too low, many species of fish, macroinvertebrates, and plants cannot survive. At very low levels of oxygen, the stream becomes "septic" and smells rotten because low oxygen sulfur bacteria begin to dominate.

  20. Dissolved Oxygen Model

    NSDL National Science Digital Library

    Steve Gordon

    One of the most important measures of the health of the stream is the level of dissolved oxygen (DO) in the water. Oxygen (O2) dissolves in water through the mixing of the water surface with the atmosphere. The oxygen is used by fish and other animals in the water to "breath" through their gills or other respiratory systems and by plants. If the levels fall too low, many species of fish, macroinvertebrates, and plants cannot survive. At very low levels of oxygen, the stream becomes "septic" and smells rotten because low oxygen sulfur bacteria begin to dominate.

  1. Oxygen transport—the oxygen delivery controversy

    Microsoft Academic Search

    Jean-Louis Vincent; Daniel De Backer

    Most cellular activities require energy in the form of oxygen, primarily obtained from the degradation of adenosine triphosphate\\u000a (ATP) and other high-energy compounds. Oxygen must be present in sufficient amounts in the mitochondria to maintain effective\\u000a concentrations of ATP in the electron transport system. Cells have to perform a series of activities essential for survival,\\u000a including membrane transport, growth, cellular

  2. 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.

  3. 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. PMID:16566709

  4. Oxygen partial pressure sensor

    DOEpatents

    Dees, Dennis W. (Downers Grove, IL)

    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.

  5. Oxygen pressure measurement using singlet oxygen emission

    SciTech Connect

    Khalil, Gamal E.; Chang, Alvin; Gouterman, Martin; Callis, James B.; Dalton, Larry R.; Turro, Nicholas J.; Jockusch, Steffen [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States); Department of Chemistry, Columbia University, New York, New York 10027 (United States)

    2005-05-15

    Pressure sensitive paint (PSP) provides a visualization of two-dimensional pressure distributions on airfoil and model automobile surfaces. One type of PSP utilizes platinum tetra(pentafluorophenyl)porphine (PtTFPP) dissolved in a fluoro-polymer film. Since the intense 650 nm triplet emission of PtTFPP is quenched by ground state oxygen, it is possible to measure two-dimensional oxygen concentration from the 650 nm emission intensity using a Stern-Volmer-type relationship. This article reports an alternative luminescence method to measure oxygen concentration based on the porphyrin-sensitized 1270 nm singlet oxygen emission, which can be imaged with an InGaAs near infrared camera. This direct measurement of oxygen emission complements and further validates the oxygen measurement based on PtTFPP phosphorescence quenching. Initial success at obtaining a negative correlation between the 650 nm PtTFPP emission and the 1270 nm O{sub 2} emission in solution led us to additional two-dimensional film studies using surfaces coated with PtTFPP, MgTFPP, and H{sub 2}TFPP in polymers in a pressure and temperature controlled chamber.

  6. How Does Oxygen Therapy Work?

    MedlinePLUS

    ... page from the NHLBI on Twitter. How Does Oxygen Therapy Work? Oxygen therapy provides you with extra ... be delivered to your lungs in several ways. Oxygen Therapy Systems Oxygen is supplied in three forms: ...

  7. Inflation Calculator

    NSDL National Science Digital Library

    Friedman, S. Morgan.

    This simple inflation calculator uses the Consumer Price Index to adjust any given amount of money, from 1800 to 1998. Creator S. Morgan Friedman uses data from the Historical Statistics of the United States for statistics predating 1975 and the annual Statistics Abstracts of the United States for data from 1975 to 1998. Links to other online inflation information are also included.

  8. Mercury Calculator

    NSDL National Science Digital Library

    2010-09-16

    This interactive calculator produced by Teachers' Domain helps you determine the mercury levels in various types of fish, and enables you to make more informed choices about which fish are safe to eat and which should be avoided or eaten infrequently.

  9. Comparative quantification of oxygen release by wetland plants: electrode technique and oxygen consumption model.

    PubMed

    Wu, Haiming; Liu, Jufeng; Zhang, Jian; Li, Cong; Fan, Jinlin; Xu, Xiaoli

    2014-01-01

    Understanding oxygen release by plants is important to the design of constructed wetlands for wastewater treatment. Lab-scale systems planted with Phragmites australis were studied to evaluate the amount of oxygen release by plants using electrode techniques and oxygen consumption model. Oxygen release rate (0.14 g O2/m(2)/day) measured using electrode techniques was much lower than that (3.94-25.20 gO2/m(2)/day) calculated using the oxygen consumption model. The results revealed that oxygen release by plants was significantly influenced by the oxygen demand for the degradation of pollutants, and the oxygen release rate increased with the rising of the concentration of degradable materials in the solution. The summary of the methods in qualifying oxygen release by wetland plants demonstrated that variations existed among different measuring methods and even in the same measuring approach. The results would be helpful for understanding the contribution of plants in constructed wetlands toward actual wastewater treatment. PMID:23872897

  10. 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.

  11. 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.

  12. 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.

  13. 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. PMID:24461631

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Secret Agents of Dissolved Oxygen

    NSDL National Science Digital Library

    Besse Dawson

    This activity explores how water chemistry is altered by the biological processes of phytoplankton (microscopic photosynthetic organisms). Students will discover what some of these water chemistry changes are, and what influences these changes (type of water, exposure to light, etc.). The students will design an activity based on experience gained from the first activity. They will determine the changes and causes thereof in different types of water in a sealed container over time, and learn to measure dissolved oxygen, temperature, and carbon dioxide with a calculator/computer probe-ware or by other means.

  16. 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.

  17. Rockets using Liquid Oxygen

    NASA Technical Reports Server (NTRS)

    Busemann, Adolf

    1947-01-01

    It is my task to discuss rocket propulsion using liquid oxygen and my treatment must be highly condensed for the ideas and experiments pertaining to this classic type of rocket are so numerous that one could occupy a whole morning with a detailed presentation. First, with regard to oxygen itself as compared with competing oxygen carriers, it is known that the liquid state of oxygen, in spite of the low boiling point, is more advantageous than the gaseous form of oxygen in pressure tanks, therefore only liquid oxygen need be compared with the oxygen carriers. The advantages of liquid oxygen are absolute purity and unlimited availability at relatively small cost in energy. The disadvantages are those arising from the impossibility of absolute isolation from heat; consequently, allowance must always be made for a certain degree of vaporization and only vented vessels can be used for storage and transportation. This necessity alone eliminates many fields of application, for example, at the front lines. In addition, liquid oxygen has a lower specific weight than other oxygen carriers, therefore many accessories become relatively larger and heavier in the case of an oxygen rocket, for example, the supply tanks and the pumps. The advantages thus become effective only in those cases where definitely scheduled operation and a large ground organization are possible and when the flight requires a great concentration of energy relative to weight. With the aim of brevity, a diagram of an oxygen rocket will be presented and the problem of various component parts that receive particularly thorough investigation in this classic case but which are also often applicable to other rocket types will be referred to.

  18. Broken Calculator

    NSDL National Science Digital Library

    Mandy Barrow

    2008-01-01

    This interactive applet helps students develop fluency and flexibility with numbers. At each of 6 difficulty levels the user is presented with 8 target numbers and a partial set of keys on a basic calculator (does not follow order of operations). The goal is to use the given keys to make as many of the target numbers as possible within the 3-minute time limit. Some levels include memory keys.

  19. 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).

  20. Life Before Oxygen

    NSDL National Science Digital Library

    About three billion years ago, single-celled underwater bacteria similar to modern cyanobacteria consumed carbon dioxide as they photosynthesized, releasing oxygen in the process. In this way, an atmosphere full of volcanic carbon dioxide gradually changed into an oxygen-rich atmosphere in which animal life could survive, except for some primitive organisms, who retreated to oxygen-poor environments. This video segment shows researchers as they search for these organisms, which are now considered tiny time capsules from the time before there was oxygen on Earth. The segment is one minute thirty-nine seconds in length. A background essay and list of discussion questions are also provided.

  1. 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.

  2. Oscillator strengths for singly ionized oxygen

    Microsoft Academic Search

    ?. Ate?; G. Tekeli; G. Çelik; E. Akin; M. Taser

    2009-01-01

    The electric dipole oscillator strengths for multiplet and \\u000a individual lines between some doublet and quartet levels have been \\u000a calculated using the weakest bound electron potential model theory (WBEPMT) \\u000a in singly ionized oxygen. We employed both numerical Coulomb approximation \\u000a (NCA) wave functions and numerical non-relativistic Hartree-Fock (NRHF) wave \\u000a functions for expectation values of radii in determination of parameters. \\u000a The calculated oscillator

  3. Oxygenated fuel cost may outweigh effectiveness

    SciTech Connect

    Illman, D.

    1993-04-12

    When Coloradans became the first in the nation ordered to use oxygenated fuel in wintertime, the goal was to diminish the concentration of carbon monoxide in the atmosphere. But the University of Colorado, Denver, claims that data collected at a downtown Denver location show that use of oxygenated fuel has had no statistically significant effect on atmospheric carbon monoxide concentrations and may actually increase levels of other pollutants such as formaldehyde. Officials have estimated the effect of the program on atmospheric carbon monoxide concentration by extrapolating results of vehicle emissions tests, using a theoretical emissions model to calculate the overall reduction of carbon monoxide expected in the Denver atmosphere. The assumptions in that model are inaccurate, and moreover, official assessments have failed to adequately incorporate real experimental data in their calculations. This paper discusses these results and also the possible harmful effects from methyl tert-butyl ether, the oxygenate added to gasoline in the Denver area.

  4. An improved program to calculate intrapulmonary shunting.

    PubMed

    Siegel, D; Ramanathan, S; Chalon, J; Turndorf, H

    1979-06-01

    A computer program was developed to calculate intrapulmonary venous admixture on a Texas Instruments TI 59 programmable calculator. The program incorporates the following characteristics: 1) a correction for saturated water vapor pressure which varies with body temperature; 2) a mathematical model of the standard oxyhemoglobin dissociation curve; and 3) correction factors for shifts of the dissociation curve due to variations in pH and carbon dioxide tension. It also corrects oxygen tensions obtained at electrode temperature to those at patient temperature, and calculates variations of the Bunsen solubility coefficient of oxygen in blood with body temperature. PMID:446063

  5. Chemical Calculations

    NSDL National Science Digital Library

    Goodman, Jonathan

    This site contains many chemistry applets created by Jonathan Goodman and his group at Cambridge University. An example of an applet available is the Molecular Weight Calculation; whereby entering in a molecular formula, users are able to discover the HRMS weight, the molecular weight, the element percents, and the Molecular Ion Isotope Pattern. Interactive graphs are also available to assist chemistry students with concepts such as boiling points, pressure, and Consecutive First Step Reversible Reactions. Educators and students will also find many three dimensional depictions of the molecules including fused rings, aromatic rings, and Fullerenes.

  6. Photoperiod Calculator

    NSDL National Science Digital Library

    Lammi, Jarmo J.

    Jarmo Lammi has developed this simple, easy-to-use tool that provides information useful for teaching and research purposes. Users select a day, month, location (city or latitude and longitude) and time-of-day, and then submit their entry. The Calculator then generates the following information: latitude and longitude for the city/location, declination of the sun, height of sun at noon that day, daylength, and time of sunrise and sunset. This is a useful tool for ecological research and teaching.

  7. Accuracy of oxygen delivery by liquid oxygen canisters

    Microsoft Academic Search

    M. J. Kampelmacher; P. B. Cornelisse; G. P. J. Alsbach; R. G. van Kesteren; C. F. Melissant; J. M. C. Douze; J. W. J. Lammers

    1998-01-01

    The oxygen flow rate delivered by liquid oxygen canisters may be less than intended, owing to inaccuracies of the set flow rates and\\/or as a result of the out- flow resistance caused by the humidifier, oxygen tubing, delivery or conserving device. The aim of this study was to investigate the accuracy of oxygen delivery by liq- uid oxygen canisters at

  8. Glovebox oxygen monitoring system

    Microsoft Academic Search

    Haggard

    1993-01-01

    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

  9. Aircrew oxygen system

    NASA Technical Reports Server (NTRS)

    Babinsky, A. D.; Kiraly, R. J.; Wynveen, R. A.

    1972-01-01

    Closed-loop rebreather system which includes pilot provides oxygen for use in aircraft by safe, reliable method of low weight and size and reduces expense of ground equipment. Water electrolysis generated oxygen is fed into rebreather loop which allows nitrogen elimination and water and carbon dioxide removal.

  10. Oxygen consumption in Diaptomus

    Microsoft Academic Search

    GABRIEL W. COMITA

    1968-01-01

    The oxygen consumption of fed and unfed Diaptomus siciloides, D. oregonensis, D. Zeptopus, and D. &wipes was measured at five different tcmpcraturcs using a micro- Winkler technique. Regression relationships between log oxygen uptake and each of the following independent variables, tcmperaturc, log length, and log weight, as well as the combinations of temperature and length and of temperature and weight,

  11. Production of Oxygen

    NSDL National Science Digital Library

    The Science House

    2014-01-28

    In this chemistry activity, learners use yeast and hydrogen peroxide to generate a gas (oxygen) and test some of its properties. This resource includes brief questions for learners to answer after the experiment. Use this activity to introduce learners to oxygen as well as combustion. Note: this activity involves an open flame.

  12. Extracorporeal membrane oxygenation circuitry.

    PubMed

    Lequier, Laurance; Horton, Stephen B; McMullan, D Michael; Bartlett, Robert H

    2013-06-01

    The extracorporeal membrane oxygenation circuit is made of a number of components that have been customized to provide adequate tissue oxygen delivery in patients with severe cardiac and/or respiratory failure for a prolonged period of time (days to weeks). A standard extracorporeal membrane oxygenation circuit consists of a mechanical blood pump, gas-exchange device, and a heat exchanger all connected together with circuit tubing. Extracorporeal membrane oxygenation circuits can vary from simple to complex and may include a variety of blood flow and pressure monitors, continuous oxyhemoglobin saturation monitors, circuit access sites, and a bridge connecting the venous access and arterial infusion limbs of the circuit. Significant technical advancements have been made in the equipment available for short- and long-term extracorporeal membrane oxygenation applications. Contemporary extracorporeal membrane oxygenation circuits have greater biocompatibility and allow for more prolonged cardiopulmonary support time while minimizing the procedure-related complications of bleeding, thrombosis, and other physiologic derangements, which were so common with the early application of extracorporeal membrane oxygenation. Modern era extracorporeal membrane oxygenation circuitry and components are simpler, safer, more compact, and can be used across a wide variety of patient sizes from neonates to adults. PMID:23735989

  13. Oxygen solubilities of media used in electrochemical respiration measurements

    Microsoft Academic Search

    Hans N Rasmussen; Ulla F Rasmussen

    2003-01-01

    Solubility data are presented as equations from which the oxygen concentration of arbitrary media may be calculated with an accuracy of about 1%. These equations, covering the range 5–40°C, are based on measurements with a modification of the physical method of St. Helen and Fatt (I. Fatt, Polarographic Oxygen Sensors, CRC Press, Cleveland (1976)). Solutions of the following compounds were

  14. 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.

  15. Biphasic Oxygen Kinetics of Cellular Respiration and Linear Oxygen Dependence of Antimycin A Inhibited Oxygen Consumption

    Microsoft Academic Search

    Eveline Hütter; Kathrin Renner; Pidder Jansen-Dürr; Erich Gnaiger

    2002-01-01

    Oxygen kinetics in fibroblasts was biphasic. This was quantitatively explained by a major mitochondrial hyperbolic component in the low-oxygen range and a linear increase of rotenone-and antimycin A-inhibited oxygen consumption in the high-oxygen range. This suggests an increased production of reactive oxygen species and oxidative stress at elevated, air-level oxygen concentrations. The high oxygen affinity of mitochondrial respiration provides the

  16. Molecular Structure of Oxygen

    NSDL National Science Digital Library

    2006-05-01

    Diatomic oxygen (O2) is a highly reactive, paramagnetic molecule (containing two unpaired electrons) that occurs as a colorless gas at ambient temperatures but is a sapphire-blue liquid at very low temperatures (below –183 ºC). It is the second most abundant gas present in Earth's atmosphere. But it wasn't that way 4.5 billion years ago when the Earth's atmosphere was forming and N2 and CO2 were the dominant atmospheric gases. During that time, our planet was essentially devoid of oxygen, except for a small amount formed from the photodissociation of water and carbon dioxide by ultraviolet light from the sun. The oxygen that we breath today started to enter the atmosphere as a byproduct of photosynthesis carried out by early cyanobacteria 2.5 billion years ago. These bacteria thrived in the primordial oceans and were able to make organic nutrients using the light of the sun and the CO2 and water around them. During those early days, all the oxygen produced by bacteria was used up to oxidize iron that was dissolved in the oceans. It took about a hundred million years of oxygen production before all the iron precipitated, whereupon the oceans became saturated with oxygen and outgassed oxygen into the atmosphere. Today, oxygen continues to be produced photosynthetically by phytoplankton and green plants that have since evolved on Earth. Marine and terrestrial animals alike use the oxidizing power of dioxygen to pull electrons from organic molecules in electron transport systems that make up their metabolisms (aerobic respiration). Related to this is the best known reaction of diatomic oxygen: the reaction of O2 with the protein hemoglobin that that is responsible for oxygen transport in our blood.

  17. Oxygen requirement in pullulan fermentation

    Microsoft Academic Search

    Denis Rho; Ashok Mulchandani; John H. T. Luong; Anh LeDuy

    1988-01-01

    Oxygen was essential for the biosynthesis of pullulan by Aureobasidium pullulans. In a growth medium, pullulan yield and synthesis rate were proportional to the oxygen availability. However, under controlled oxygen environment in a non-growth medium, the synthesis rate and the yield of pullulan were inversely proportional to the oxygen tension. A relationship between melanin production and oxygen transfer conditions was

  18. Oxygen Toxicity Calculations by Erik C. Baker, P.E.

    E-print Network

    Read, Charles

    the parameter of most concern and greatest impact in technical diving, however some "mega-dives" undertaken is an important element of technical diving. Most often this is accomplished during the dive planning stage through the use of a dive/decompression planning program on a computer. Having developed such a program

  19. Probability Calculator

    NSDL National Science Digital Library

    Stark, Philip B.

    This tool lets you calculate the probability that a random variable X is in a specified range, for a variety of probability distributions for X: the normal distribution, the binomial distribution with parameters n and p, the chi-square distribution, the exponential distribution, the geometric distribution, the hypergeometric distribution, the negative binomial distribution, the Poisson distribution, and Student's t-distribution. The first choice box lets you select a probability distribution. Depending on the distribution you select, text areas will appear for you to enter the values of the parameters of the distribution. Parameters that are probabilities (e.g., the chance of success in each trial for a binomial distribution) can be entered either as decimal numbers between 0 and 1, or as percentages. If you enter a probability as a percentage, be sure to include the percent sign (%) after the number.

  20. 42 CFR 414.226 - Oxygen and oxygen equipment.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...CONTINUED) MEDICARE PROGRAM PAYMENT FOR PART B MEDICAL AND OTHER HEALTH SERVICES Payment for Durable Medical Equipment and Prosthetic and Orthotic Devices § 414.226 Oxygen and oxygen equipment. (a) Payment rules —(1) Oxygen...

  1. 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. PMID:23670967

  2. 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.

  3. Hyperbaric oxygen in neurosurgery

    Microsoft Academic Search

    B. R. Fischer; E. J. Speckmann; C. Greiner; A. Gorji; J. Wölfer; H. Wassmann

    2009-01-01

    Background  The therapeutic use of pure oxygen, even under hyperbaric conditions, has been well established for about 50 years, whereas\\u000a the discovery of oxygen occurred 250 years earlier. Many neurosurgical patients suffer from brain tissue damage, due to reduced\\u000a blood flow, obstructive vessel disease, or as a result of traumatic brain injury.\\u000a \\u000a \\u000a \\u000a Methods and results  The application of pure oxygen in these patients is

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

    SciTech Connect

    Lewis, E.; Wallace, D. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science; Allison, L.J. [Oak Ridge National Lab., TN (United States). Carbon Dioxide Information Analysis Center

    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.

  5. 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.

  6. 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...

  7. 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.

  8. Traveling with Portable Oxygen

    MedlinePLUS

    ... your blood while you breathe a mixture of gases similar to the atmosphere inside a pressurized airplane ... a high-altitude destination, such as a mountainous area, you may need to plan for portable oxygen ...

  9. 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)

  10. Collect Oxygen Over Water

    NSDL National Science Digital Library

    2014-10-03

    In this activity, learners use a pneumatic trough (see related activity) to generate and collect pure oxygen. Learners will test to see if they've generated oxygen by observing the combustion of elemental sulfur, which yields a brilliant blue flame of sulfur oxidation. The manganese dioxide catalyst used in this process is easily recovered from a spent zinc-carbon battery (see related activity).

  11. International Geology Review, 2013 Vol. 55, No. 11, 14181444, http://dx.doi.org/10.1080/00206814.2013.780722

    E-print Network

    . The corresponding oxygen fugacity (f O2) was calculated to range from FMQ ­2.64 to +0.39 with an average of ­0.59 (n; mineral chemistry; oxidation state (f O2); upwelling asthenosphere; North China Craton Introduction Oxygen within the mantle and between mantle and crust (Frost and McCammon 2008). It affects metal mobility, gas

  12. 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.

  13. Thermodynamic and spectroscopic properties of oxygen on silver under an oxygen atmosphere.

    PubMed

    Jones, Travis E; Rocha, Tulio C R; Knop-Gericke, Axel; Stampfl, Catherine; Schlögl, Robert; Piccinin, Simone

    2015-04-14

    We report on a combined density functional theory and the experimental study of the O1s binding energies and X-ray Absorption Near Edge Structure (XANES) of a variety of oxygen species on Ag(111) and Ag(110) surfaces. Our theoretical spectra agree with our measured results for known structures, including the p(N× 1) reconstruction of the Ag(110) surface and the p(4 × 4) reconstruction of the Ag(111) surface. Combining the O1s binding energy and XANES spectra yields unique spectroscopic fingerprints, allowing us to show that unreconstructed atomic oxygen is likely not present on either surface under equilibrium conditions at oxygen chemical potentials typical for ethylene epoxidation. Furthermore, we find no adsorbed or dissolved atomic species whose calculated spectroscopic features agree with those measured for the oxygen species believed to catalyze the partial oxidation of ethylene. PMID:25760562

  14. Muon transfer from muonic hydrogen to atomic oxygen and nitrogen

    SciTech Connect

    Le, Anh-Thu; Lin, C D. [Department of Physics, Cardwell Hall, Kansas State University, Manhattan, Kansas 66506 (United States)

    2005-02-01

    The results of diabatic hyperspherical close-coupling calculations are presented for the charge exchange of a negative muon from muonic hydrogen to oxygen and nitrogen for collision energies from 10{sup -3} to 10{sup 3} eV. It is shown that converged results can be obtained using a much smaller number of channels than in the traditional adiabatic approach. For the energy range below 10 eV our results for nitrogen are in good agreements with the available experimental data and the recent calculations within hyperspherical elliptic coordinates. However, discrepancies were found in the case of oxygen, where a p-wave shape resonance is shown to contribute significantly to the cross sections. We show that for oxygen the p-wave resonance extends to a large volume and is sensitive to the many-body effect. Calculations including outer screening of the oxygen atom have been performed to illustrate the importance of this effect.

  15. Experimental and theoretical investigation of oxygen diffusion in stabilised zirconia

    NASA Astrophysics Data System (ADS)

    Kilo, M.; Fundenberger, C.; Argirusis, C.; Taylor, M. A.; Borchardt, G.; Weller, M.; Jackson, R. A.

    Oxygen diffusion in stabilised zirconias is investigated by the simultaneous application of computer modelling and experimental techniques to yttria-stabilised zirconia. Using the Mott-Littleton method, migration pathways for oxygen ions have been calculated in perfect cubic zirconia. The oxygen migration occurs through a straight pathway, but not starting from the ideal lattice positions. The calculated activation energy of migration is about 0.2 eV. Oxygen transport is investigated experimentally in YSZ containing 8-24 mol% Y2O3 as a function of stabiliser content by combining the stable isotope (O-18(2)) method with ionic conductivity measurements. It was found that for a given temperature, diffusion and conductivity are highest for YSZ containing 8-10 mol% yttria, but with differing activation energies which can be compared to the calculated values.

  16. Improved binding between copper and carbon nanotubes in a composite using oxygen-containing functional groups

    Microsoft Academic Search

    Mina Park; Byung-Hyun Kim; Sanghak Kim; Do-Suck Han; Gunn Kim; Kwang-Ryeol Lee

    2011-01-01

    The adsorption of Cu on defective carbon nanotubes (CNTs) functionalized with various surface functional groups, including atomic oxygen (–O), hydroxyl (–OH) and carboxyl (–COOH) groups, was investigated by density functional theory calculation. The chemical interaction analysis revealed that the oxygen of the surface functional group can enhance the interaction between the carbon and Cu. The oxygen of the functional group

  17. Oxygen consumption through metabolism and photodynamic reactions in cells cultured on microbeads

    Microsoft Academic Search

    T. Schunck; P. Poulet

    2000-01-01

    Oxygen consumption by cultured cells, through metabolism and photosensitization reactions, has been calculated theoretically. From this result, we have derived the partial oxygen pressure PO2 in the perfusion medium flowing across sensitized cultured cells during photodynamic experiments. The PO2 variations in the perfusate during light irradiation are related to the rate of oxygen consumption through photoreactions, and to the number

  18. Dentrification and oxygen consumption in bottom sediments: factors influencing rates of the processes

    Microsoft Academic Search

    J. A. Tomaszek; E. Czerwieniec

    2003-01-01

    Rates of denitrification and oxygen consumption were measured in the sediment of four reservoirs in south-eastern Poland using an in situ chamber method. The in situ denitrification rate was calculated from the total N2 flux from sediment, and the rate of oxygen consumption from the differences as a function of time in dissolved oxygen concentration in overlying water enclosed within

  19. Photochemical escape of oxygen from early Mars

    NASA Astrophysics Data System (ADS)

    Zhao, Jinjin; Tian, Feng

    2015-04-01

    Photochemical escape is an important process for oxygen escape from present Mars. In this work, a 1-D Monte-Carlo Model is developed to calculate escape rates of energetic oxygen atoms produced from O2+ dissociative recombination reactions (DR) under 1, 3, 10, and 20 times present solar XUV fluxes. We found that although the overall DR rates increase with solar XUV flux almost linearly, oxygen escape rate increases from 1× to 10× present solar XUV conditions but decreases when increasing solar XUV flux further. Analysis shows that atomic species in the upper thermosphere of early Mars increases more rapidly than O2+ when increasing XUV fluxes. While the latter is the source of energetic O atoms, the former increases the collision probability and thus decreases the escape probability of energetic O. Our results suggest that photochemical escape be a less important escape mechanism than previously thought for the loss of water and/or CO2 from early Mars.

  20. 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.

  1. Photochemical Escape of Oxygen from Early Mars

    E-print Network

    Zhao, Jinjin

    2015-01-01

    Photochemical escape is an important process for oxygen escape from present Mars. In this work, a 1-D Monte-Carlo Model is developed to calculate escape rates of energetic oxygen atoms produced from O2+ dissociative recombination reactions (DR) under 1, 3, 10, and 20 times present solar XUV fluxes. We found that although the overall DR rates increase with solar XUV flux almost linearly, oxygen escape rate increases from 1 to 10 times present solar XUV conditions but decreases when increasing solar XUV flux further. Analysis shows that atomic species in the upper thermosphere of early Mars increases more rapidly than O2+ when increasing XUV fluxes. While the latter is the source of energetic O atoms, the former increases the collision probability and thus decreases the escape probability of energetic O. Our results suggest that photochemical escape be a less important escape mechanism than previously thought for the loss of water and/or CO2 from early Mars.

  2. OXYGEN TRANSPORT MEMBRANE (OTM) AIDED

    E-print Network

    OXYGEN TRANSPORT MEMBRANE (OTM) AIDED OXYGEN ENHANCED COMBUSTION Prepared For: California Energy-2005-088 #12;#12;ENERGY INNOVATIONS SMALL GRANT (EISG) PROGRAM INDEPENDENT ASSESSMENT REPORT (IAR) OXYGEN TRANSPORT MEMBRANE (OTM) AIDED OXYGEN ENHANCED COMBUSTION EISG AWARDEE University of Southern California

  3. 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.

  4. 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.

  5. Battling for Oxygen

    NSDL National Science Digital Library

    Amy Kolenbrander

    2004-01-01

    Working in groups, learners model the continuous destruction and creation of ozone (O3) molecules, which occur in the ozone layer. Some learners act as ultraviolet (UV) light and break apart gumdrop and toothpick models of ozone molecules into oxygen molecules and atoms. Meanwhile, other learners assemble ozone molecules from the oxygen molecules and atoms. In a second round, learners model the situation when pollutants such as chlorofluorocarbons (CFCs) are present. In subsequent rounds, the amount of CFCs changes according to historical data, and learners can see what happens to the proportion of ozone and oxygen in the ozone layer over time. Resource contains vocabulary definitions and suggestions for assessment, extensions, and scaling for different levels of learners.

  6. 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…

  7. Interactions of Oxygen and Hydrogen on Pd(111) surface

    SciTech Connect

    Demchenko, D.O.; Sacha, G.M.; Salmeron, M.; Wang, L.-W.

    2008-06-25

    The coadsorption and interactions of oxygen and hydrogen on Pd(1 1 1) was studied by scanning tunneling microscopy and density functional theory calculations. In the absence of hydrogen oxygen forms a (2 x 2) ordered structure. Coadsorption of hydrogen leads to a structural transformation from (2 x 2) to a ({radical}3 x {radical}3)R30 degree structure. In addition to this transformation, hydrogen enhances the mobility of oxygen. To explain these observations, the interaction of oxygen and hydrogen on Pd(1 1 1) was studied within the density functional theory. In agreement with the experiment the calculations find a total energy minimum for the oxygen (2 x 2) structure. The interaction between H and O atoms was found to be repulsive and short ranged, leading to a compression of the O islands from (2 x 2) to ({radical}3 x {radical}3)R30 degree ordered structure at high H coverage. The computed energy barriers for the oxygen diffusion were found to be reduced due to the coadsorption of hydrogen, in agreement with the experimentally observed enhancement of oxygen mobility. The calculations also support the finding that at low temperatures the water formation reaction does not occur on Pd(1 1 1).

  8. Seasonal changes in the oxygen storage capacity and aerobic dive limits of the muskrat ( Ondatra zibethicus )

    Microsoft Academic Search

    Robert A. MacArthur

    1990-01-01

    The oxygen storage capacity and partitioning of body oxygen reserves were compared in summer-and winter-acclimatized muskrats (Ondatra zibethicus). Blood volume, blood oxygen capacity, and skeletal muscle myoglobin content were higher in December than in July (PP>0.05). The oxygen storage capacity of a diving muskrat was calculated at 25.2 ml O2 STPD · kg-1 in July, compared to 35.7 ml O2

  9. Life with Oxygen

    NSDL National Science Digital Library

    Gregg L. Semenza (The Johns Hopkins University School of Medicine; Vascular Program, Institute for Cell Engineering; Departments of Pediatrics, Medicine, Oncology, Radiation Oncology; and McKusick-Nathans Institute of Genetic Medicine)

    2007-10-05

    Access to the article is free, however registration and sign-in are required. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that functions as a master regulator of oxygen homeostasis and has essential roles in metazoan development, physiology, and disease pathogenesis. Remarkable progress has been made in delineating the molecular mechanisms whereby changes in cellular oxygenation are transduced to the nucleus as changes in gene transcription through the activity of HIF-1. Pharmacologic agents that activate or inhibit the hypoxia signal transduction pathway may be useful therapies for ischemic and neoplastic disorders, respectively, which are the major causes of mortality in industrialized societies.

  10. 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 temperature exhibited a strong correlation to adhesion of the Au thin film to the FEP. Adhesion of the Au thin film with a FEP temperature of 50°C was rated a 3B per the ASTM D3359-02 peel test standard. At FEP substrate temperature of -77°C it was rated at 1B. The morphology of the deposited Au thin films was observed using optical microscopy and Scanning Electron Microscopy (SEM).

  11. Hyperbaric oxygen therapy.

    PubMed

    Braswell, Cheryl; Crowe, D Tim

    2012-03-01

    Hyperbaric oxygen therapy (HBOT) is emerging in veterinary medicine as an effective treatment or adjunct therapy for a variety of disorders in which improving oxygen delivery to tissues is a priority. The primary mechanisms of action of HBOT are (1) immediate hyperoxygenation of plasma and tissues and (2) decreased gas bubble (air embolus) size. With each hyperbaric 'dive,' secondary physiologic effects are set into motion. This article provides an introduction to HBOT, as well as its benefits, potential indications, contraindications, complications, and future directions in small animal veterinary medicine. PMID:22487778

  12. Murder Mystery for Student Practice of Pulmonary Physiology Calculations

    NSDL National Science Digital Library

    Michael B Maron (Northeastern Ohio Universities College of Medicine Department of Physiology)

    1991-12-01

    Exercise for students used to practice measuring arterial oxygen content and delivery, physiological deadspace, dead space and alveolar ventilation, and alveolar partial pressure of oxygen and carbon dioxide. NOTE:There is an error in Table 4 (entitled "Ventilatory calculations"). The "mixed expiratory PCO2" under control conditions for Victor should be 23.6 torr rather than the published value of 17 torr.

  13. The Effects of Photosynthesis and Cellular Respiration on Dissolved Oxygen Concentration

    Microsoft Academic Search

    Darren Proppe; Sherry Harrel

    2007-01-01

    Photosynthesis and cellular respiration are two processes that transform energy and affect concentrations of carbon dioxide and oxygen in air and water. In this lesson, middle school students use graphing calculators and calculator-based laboratory units to measure dissolved oxygen in water and graph their results to gain an under-standing of the relationship between photosynthesis and cellular respiration.

  14. Kinetics of melted copper oxidation with oxygen of the gas phase

    NASA Astrophysics Data System (ADS)

    Lyamkin, S. A.; Tanutrov, I. N.; Sviridova, M. N.

    2013-08-01

    The oxidation of melted copper with air oxygen is considered from a viewpoint of the electrochemical theory of interactions at the melt-oxygen-containing gas interface. The calculations using the experimental data show that the process proceeds in a kinetic regime. The rate-determining step is the detachment of the first electron from an adsorbed oxygen atom. The oxidation of liquid copper in a circulation gas lift is calculated.

  15. Oxygen transport by oxygen potential gradient in dense ceramic oxide membranes

    SciTech Connect

    Maiya, P.S.; Balachandran, U.; Dusek, J.T.; Mieville, R.L. [Argonne National Lab., IL (United States). Energy Technology Div.; Kleefisch, M.S.; Udovich, C.A. [Amoco Exploration/Production, Naperville, IL (United States)

    1996-05-01

    Numerous studies have been conducted in recent years on the partial oxidation of methane to synthesis gas (syngas: CO + H{sub 2}) with air as the oxidant. In partial oxidation, a mixed-oxide ceramic membrane selectively transports oxygen from the air; this transport is driven by the oxygen potential gradient. Of the several ceramic materials the authors have tested, a mixed oxide based on the Sr-Fe-Co-O system has been found to be very attractive. Extensive oxygen permeability data have been obtained for this material in methane conversion experiments carried out in a reactor. The data have been analyzed by a transport equation based on the phenomenological theory of diffusion under oxygen potential gradients. Thermodynamic calculations were used to estimate the driving force for the transport of oxygen ions. The results show that the transport equation deduced from the literature describes the permeability data reasonably well and can be used to determine the diffusion coefficients and the associated activation energy of oxygen ions in the ceramic membrane material.

  16. The history of extracorporeal oxygenators.

    PubMed

    Lim, M W

    2006-10-01

    Extracorporeal oxygenators are artificial devices that substitute for anatomical lungs by delivering oxygen to, and extracting carbon dioxide from, blood. They were first conceptualised by the English scientist Robert Hooke (1635-1703) and developed into practical extracorporeal oxygenators by French and German experimental physiologists in the 19th century. Indeed, most of the extracorporeal oxygenators used until the late 1970s were derived from von Schroder's 1882 bubble oxygenator and Frey and Gruber's 1885 film oxygenator. As there is no intervening barrier between blood and oxygen, these are called 'direct contact' oxygenators; they contributed significantly to the development and practice of cardiac surgery till the 1980s. Membrane extracorporeal oxygenators introduce a gas-permeable interface between blood and oxygen. This greatly decreased the blood trauma of direct-contact extracorporeal oxygenators, and enabled extracorporeal oxygenators to be used in longer-term applications such as the intensive therapy of respiratory distress syndrome; this was demonstrably beneficial for neonates but less so for older patients. Much work since the 1960s focused on overcoming the gas exchange handicap of the membrane barrier, leading to the development of high-performance microporous hollow-fibre oxygenators that eventually replaced direct-contact oxygenators in cardiac theatres. PMID:16978315

  17. 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…

  18. 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.

  19. Oxygenate liquid transportation fuels

    Microsoft Academic Search

    Stiegel

    2009-01-01

    These oxygenates are alcohols, mixed alcohols, ethers, and synthesis gas olefins. PETC projects for producing these fuels are described. Previous approaches to controlling automobile emissions have focused almost exclusively on redesigning the engine and exhaust system. The Clean Air Act Amendments of 1990 expanded that focus to include investigating alternative fuels for internal combustion engines because there are fuels that

  20. Oxygen radicals and signaling

    Microsoft Academic Search

    Toren Finkel

    1998-01-01

    Recent evidence suggests that reactive oxygen species, such as superoxide anions and hydrogen peroxide, function as intracellular second messengers. This review will discuss the progress in understanding the intracellular pathways leading from ligand stimulation to the generation of oxidants, as well as some of the increasing number of cellular processes that appear to be subject to redox regulation.

  1. Optical oxygen concentration monitor

    DOEpatents

    Kebabian, Paul (Acton, MA)

    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.

  2. 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.

  3. FUEL OXYGENATES HEALTH ISSUES

    EPA Science Inventory

    Oxygenates (e.g., methyl tertiary butyl ether [MTBE], ethanol) are required in certain areas of the United States by the 1990 Clean Air Act Amendments. MTBE and ethanol have also been used to increase octane ratings in U.S. gasoline since the 1970s. In 1996 alone, 10 billion Kg...

  4. 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)

  5. Using Excel to Calculate Mineral Chemical Analyses

    NSDL National Science Digital Library

    In this assignment, students are provided instructions to make an Excel spreadsheet to calculate mineral chemical analyses from weight percent to atoms per given number of oxygen atoms. This skill will be useful for the major rock-forming mineral groups.

  6. Calculating Thermophysical Properties Of 12 Fluids

    NASA Technical Reports Server (NTRS)

    Cleghorn, T. F.; Mccarty, R. D.

    1991-01-01

    MIPROPS is set of computer programs giving thermophysical and transport properties of selected fluids. Calculates properties of fluids in both liquid and vapor states over wide range of temperatures and pressures. Fluids included: helium, hydrogen, nitrogen, oxygen, argon, nitrogen trifluoride, methane, ethylene, ethane, propane, isobutane, and normal butane. All programs except helium program incorporate same equation of state. Written in FORTRAN 77.

  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 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 the LSCrF-2828 membrane to produce the gradients which exist under syngas generation conditions. The CO-CO{sub 2} mixtures have normal isotopic {sup 18}O abundances. The evolution of {sup 18}O on the delivery side in these experiments after an {sup 18}O pulse on the air side reveals a wealth of information about the oxygen transport processes.

  8. Oxygen Pickup Ions at Mars: Model Comparisons with MAVEN Data and Implications for Oxygen Escape

    NASA Astrophysics Data System (ADS)

    Cravens, Tom; Rahmati, Ali; Larsen, Davin; Lillis, Rob; Connerney, Jack; Halekas, Jasper; Bougher, Stephen W.

    2015-04-01

    A major source of atmospheric escape on Mars is the dissociative recombination of O2+ in the ionosphere, which creates oxygen atoms with energies exceeding the escape energy. These atoms are the source of the hot oxygen exosphere of Mars, which extends to tens of Martian radii. Direct measurement of the distant oxygen exosphere, which is mainly populated with escaping neutral oxygen atoms, is difficult due to the very low densities at these distances. However, ionization of these atoms creates pickup ions that are accelerated by the solar wind convective electric field to high energies, allowing them to be measured by the SEP (Solar Energetic Particle) instrument onboard the MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft.We modeled the hot oxygen at Mars and its interaction with the solar wind using Monte Carlo and test particle methods and using densities and temperatures from the MTGCM (Mars Thermospheric General Circulation Model). The distribution function of hot oxygen atoms at 300 km is calculated using a two-stream method, and the Liouville theorem extends this distribution for the gravitationally bound and escaping parts to high altitudes. We determined the O+ flux upstream of Mars as a function of energy, and separate it into parts due both the gravitationally bound and the escaping oxygen. Significant fluxes of O+ ions are predicted for energies greater than 60 keV and have been observed by the SEP instrument, even when MAVEN was several Martian radii away from the planet. These data-model comparisons will be presented and then interpreted in terms of the escape of oxygen from Mars.

  9. Assessing hafnium on hafnia as an oxygen getter

    SciTech Connect

    O'Hara, Andrew; Demkov, Alexander A., E-mail: demkov@physics.utexas.edu [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States); Bersuker, Gennadi [SEMATECH, Albany, New York 12203 (United States)

    2014-05-14

    Hafnium dioxide or hafnia is a wide band gap dielectric used in a range of electronic applications from field effect transistors to resistive memory. In many of these applications, it is important to maintain control over oxygen stoichiometry, which can be realized in practice by using a metal layer, specifically hafnium, to getter oxygen from the adjacent dielectric. In this paper, we employ density functional theory to study the thermodynamic stability of an interface between (100)-oriented monoclinic hafnia and hafnium metal. The nudged elastic band method is used to calculate the energy barrier for migration of oxygen from the oxide to the metal. Our investigation shows that the presence of hafnium lowers the formation energy of oxygen vacancies in hafnia, but more importantly the oxidation of hafnium through the migration of oxygen from hafnia is favored energetically.

  10. 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.

  11. SINGLET OXYGEN IN NATURAL WATERS

    EPA Science Inventory

    Singlet oxygen is a reactive, electronically excited form of molecular oxygen that rapidly oxidizes a wide variety of organic substances, such as the polycyclic aromatics in petroleum hydrocarbon and the amino acids, histidine, tryptophan, and methionine. Studies of water samples...

  12. 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.

  13. MIT: Project Oxygen

    NSDL National Science Digital Library

    MIT's Project Oxygen designs computer systems that are more "human-centered" than current systems that "have required us to interact with them on their terms, speaking their languages and manipulating their keyboards or mice." The project title alludes to the group's goal of "bringing abundant computation and communication, as pervasive and free as air, naturally into people's lives." This means developing a system that is pervasive, embedded, nomadic, adaptable, powerful, yet efficient, intentional, and eternal, according to the website These criteria are met using device, network, software, perceptual, and user technologies, all of which are described on the site. Several possible applications are presented in terms of hypothetical situations where this type of system would come in handy. Demonstration videos allow visitors to view a sampling of some of the technologies being tested by Project Oxygen researchers and their industry partners.

  14. 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.

  15. High pressure oxygen furnace

    DOEpatents

    Morris, Donald E. (Kensington, CA)

    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. 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.

  17. 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.

  18. 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,...

  19. Effect of surface strain on oxygen adsorption on Zr (0001) surface

    SciTech Connect

    Xing Wang [Univ. of Wisconsin-Madison, Madison, WI (United States). Dept. of Engineering Physics; Marat Khafizov [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Izabela Szlufarska [Univ. of Wisconsin-Madison, Madison, WI (United States). Dept. of Engineering Physics; Univ. of Wisconsin-Madison, Madison, WI (United States). Dept. of Materials Science and Engineering

    2014-02-01

    The effect of surface strain on oxygen adsorption on Zr (0 0 0 1) surface is investigated by density functional theory (DFT) calculations. It is demonstrated that both surface strain and interactions between oxygen adsorbates influence the adsorption process. Oxygen binding to zirconium becomes stronger as the strain changes from compressive to tensile. When oxygen coverage is low and the oxygen interactions are negligible, surface face-centered cubic sites are the most stable for O binding. At high coverage and under compression, octahedral sites between second and third Zr layers become most favorable because the interactions between adsorbates are weakened by positive charge screening. Calculations with both single-layer adsorption model and multiple-layer adsorption model demonstrate that compressive strain at the Zr/oxide interface will provide a thermodynamic driving force for oxygen to incorporate from the surface into the bulk of Zr, while binding oxygen to the Zr surface will be easier when tensile strain is applied.

  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

    2005-02-01

    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.

  1. Fuel cell oxygen electrode

    DOEpatents

    Shanks, Howard R. (Ames, IA); Bevolo, Albert J. (Ames, IA); Danielson, Gordon C. (Ames, IA); Weber, Michael F. (Wichita, KS)

    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.

  2. Electronic state calculations of Si quantum dots: Oxidation effects

    NASA Astrophysics Data System (ADS)

    Nishida, Masahiko

    2004-04-01

    Electronic states for the configuration of a Si dihydride backbonded to oxygen on the H-covered surface of spherical Si35H36 quantum dots (QDs) are calculated self-consistently using the extended Hückel-type nonorthogonal tight-binding method. The proposed backbond oxidation accounts for oxidation-induced redshifts in luminescence-peak energy observed in porous Si. It is found that optical transitions between the band edges in the Si QD backbonded to oxygen are dipole allowed as in the H-covered case. A comparison is made with a calculation for the double-bonded oxygen configuration.

  3. Oxygen abundances in the most oxygen-rich spiral galaxies

    E-print Network

    L. S. Pilyugin; T. X. Thuan; J. M. Vilchez

    2006-01-06

    Oxygen abundances in the spiral galaxies expected to be richest in oxygen are estimated. The new abundance determinations are based on the recently discovered ff-relation between auroral and nebular oxygen line fluxes in HII regions. We find that the maximum gas-phase oxygen abundance in the central regions of spiral galaxies is 12+log(O/H)~8.75. This value is significantly lower than the previously accepted value. The central oxygen abundance in the Milky Way is similar to that in other large spirals.

  4. Investigation of oxygen point defects in cubic ZrO2 by density functional theory

    SciTech Connect

    Liu, Bin [ORNL] [ORNL; Xiao, Haiyan [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); Zhang, Yanwen [ORNL] [ORNL; Aidhy, Dilpuneet S [ORNL] [ORNL; Weber, William J [ORNL] [ORNL

    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.

  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. Oxygen sensing in the body

    Microsoft Academic Search

    S. Lahiri; A. Roy; S. M. Baby; T. Hoshi; G. L. Semenza; N. R. Prabhakar

    2006-01-01

    This review is divided into three parts: (a) The primary site of oxygen sensing is the carotid body which instantaneously respond to hypoxia without involving new protein synthesis, and is historically known as the first oxygen sensor and is therefore placed in the first section (Lahiri, Roy, Baby and Hoshi). The carotid body senses oxygen in acute hypoxia, and produces

  7. 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)

  8. 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.

  9. Steady state oxygen reduction and cyclic voltammetry.

    PubMed

    Rossmeisl, Jan; Karlberg, Gustav S; Jaramillo, Thomas; Nørskov, Jens K

    2008-01-01

    The catalytic activity of Pt and Pt3Ni for the oxygen reduction reaction is investigated by applying a Sabatier model based on density functional calculations. We investigate the role of adsorbed OH on the activity, by comparing cyclic voltammetry obtained from theory with previously published experimental results with and without molecular oxygen present. We find that the simple Sabatier model predicts both the potential dependence of the OH coverage and the measured current densities seen in experiments, and that it offers an understanding of the oxygen reduction reaction (ORR) at the atomic level. To investigate kinetic effects we develop a simple kinetic model for ORR. Whereas kinetic corrections only matter close to the volcano top, an interesting outcome of the kinetic model is a first order dependence on the oxygen pressure. Importantly, the conclusion obtained from the simple Sabatier model still persists: an intermediate binding of OH corresponds to the highest catalytic activity, i.e. Pt is limited by a too strong OH binding and Pt3Ni is limited by a too weak OH binding. PMID:19213325

  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. 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 small polaron conduction mechanism. Scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) were used to develop strategies to detect and characterize vacancy creation, dopant segregations and defect association in the oxygen conducting membrane material. The pO{sub 2} and temperature dependence of the conductivity, non-stoichiometry and thermal-expansion behavior of compositions with increasing complexity of substitution on the perovskite A and B sites were studied. Studies with the perovskite structure show anomalous behavior at low oxygen partial pressures (<10{sup -5} atm). The anomalies are due to non-equilibrium effects and can be avoided by using very strict criteria for the attainment of equilibrium. The slowness of the oxygen equilibration kinetics arises from two different mechanisms. In the first, a two phase region occurs between an oxygen vacancy ordered phase such as brownmillerite SrFeO{sub 2.5} and perovskite SrFeO{sub 3-x}. The slow kinetics is associated with crossing the two phase region. The width of the miscibility gap decreases with increasing temperature and consequently the effect is less pronounced at higher temperature. The preferred kinetic pathway to reduction of perovskite ferrites when the vacancy concentration corresponds to the formation of significant concentrations of Fe{sup 2+} is via the formation of a Ruddlesden-Popper (RP) phases as clearly observed in the case of La{sub 0.5}Sr{sub 0.5}FeO{sub 3-x} where LaSrFeO{sub 4} is found together with Fe. In more complex compositions, such as LSFTO, iron or iron rich phases are observed locally with no evidence for the presence of discrete RP phase. Fracture strength of tubular perovskite membranes was determined in air and in reducing atmospheric conditions. The strength of the membrane decreased with temperature and severity of reducing conditions although the strength distribution (Weibull parameter, m) was relatively unaltered. Surface and volume dominated the fracture origins and the overall fracture was purely transgranular. The dual phas

  12. Mantle carbon flux calculated

    NASA Astrophysics Data System (ADS)

    Wainger, Lisa

    1988-03-01

    A geochemist at the National Aeronautics and Space Administration (NASA) Ames Research Center (Moffett Field, Calif.) has greatly improved the accuracy of determining oceanic carbon outgassing rates by developing a new technique for extracting carbon dioxide that prevents contamination. David Des Marias burned his rock samples in pure oxygen at 450°C and then 650°C, before melting them at 1200°C to expel the gases. The samples remained in the same apparatus throughout the cleaning and melting, allowing Des Marais to clean the sample while limiting atmospheric contamination. His earlier work with lunar samples had shown that the process was effective, since only minor amounts of carbon were found in those samples after the cleaning.By analyzing samples of glassy ocean ridge tholeiites from the Mid-Cayman Rise, the East Pacific Rise (21°N), the Mid-Atlantic Ridge, and the Galapagos Ridge, Des Marais determined the ratio of carbon to 3He in the samples. Then, by relating that ratio to an established rate for total oceanic 3He flux, he calculated a mantle carbon flux of 20-30 million tons of carbon per year. The carbon emitted from the ocean ridges and other undersea volcanic areas represents more than 90% of the global carbon outflow from the mantle. Two other previous estimates of carbon outflow ranged from 0.1 to 10 times his result. Des Marais' finding is considered the most accurate because he was able to accurately measure carbon and 3He without depending on the assumptions made by others that all CO2 comes from volcanos and all the carbon emitted from the mantle has been preserved at the surface.

  13. Oxygen isotope thermometry, speedometry, and hygrometry: Apparent equilibrium temperature versus closure temperature

    NASA Astrophysics Data System (ADS)

    Ni, Huaiwei

    2015-01-01

    than indicating formation/peak temperature, oxygen isotope fractionations preserved in mineral assemblages of slowly cooled plutonic and metamorphic rocks yield apparent equilibrium temperatures (Tae). The isotopic fractionations and Tae values deliver information about cooling history, as the extent of diffusive exchange of oxygen isotopes during cooling is controlled by the cooling time scale or cooling rate. Despite that several models, such as the Fast Grain Boundary (FGB) model, have been developed to simulate oxygen isotope exchange between coexisting minerals during cooling, extraction of cooling rate remains far from straightforward. On the other hand, there is a well-defined quantitative relationship between the Dodson closure temperature (Tc) and the cooling rate, but Tc cannot be directly measured. Based on simulation results of existing models for a variety of rock systems, including open systems (with an infinite fluid reservoir), closed systems (with negligible fluid participation) and semi-open systems (with moderate fluid participation), this study demonstrates that Tae of the mineral pair with the largest equilibrium isotope fractionation (PLEIF) is always bounded by their Tc values, regardless of how mineral proportions vary or how significant a role fluid has played in isotopic exchange. If the two Tc values happen to be similar, Tae will serve as a good approximation of both Tc, provided that the equilibrium fractionation factor has been precisely determined as a function of temperature. One such pair is quartz-magnetite. By contrast, a mineral pair with similar Tc but relatively small fractionation is susceptible to the disturbance from other minerals, hence does not always have Tae confined within their Tc range. The relationship of Tae-Tc correspondence for PLEIF with similar Tc can be used to constrain either cooling rate (i.e., as a speedometry method) or oxygen isotope diffusivity if one of them has been independently determined. In the latter case, the inferred oxygen diffusivity may be an index of water fugacity (i.e., as a hygrometry method) when compared with experimental diffusivity values measured under different fluid conditions.

  14. Oxygen diffusion of anodic surface oxide film on titanium studied by Auger electron spectroscopy. [Oxygen diffusivity

    SciTech Connect

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

    1982-01-01

    TiO/sub 2/ films of about 1000 A were grown onto titanium foils anodically under galvanostatic conditions at 20 mA/cm/sup 2/ in saturated aqueous solutions of ammonium tetraborate. The samples were then aged at 450, 500, and 550/sup 0/C, and oxygen diffusion was observed by Auger electron spectroscopy (AES) profilings. The oxygen diffusivities were calculated by Fick's Second Law, using the Boltzmann-Matano solution, to be 9.4 x 10/sup -17/, 2.6 x 10/sup -16/, and 1.2 x 10/sup -15/ cm/sup 2//sec at 450, 500, and 550/sup 0/C, respectively. The diffusivities obtained by this method were also compared with those obtained using an exact solution to Fick's Second Law. The activation energy was calculated to be 30 kcal/mole.

  15. Circuit oxygenator contributes to extracorporeal membrane oxygenation-induced hemolysis.

    PubMed

    Williams, Duane C; Turi, Jennifer L; Hornik, Christoph P; Bonadonna, Desiree K; Williford, Walter L; Walczak, Richard J; Watt, Kevin M; Cheifetz, Ira M

    2015-01-01

    Hemolysis can occur as a consequence of extracorporeal membrane oxygenation (ECMO) and is associated with increased mortality and morbidity. Shear stress generated by flow through the circuit and oxygenator is believed to cause ECMO-induced hemolysis. We hypothesize that either a smaller dimension oxygenator or an in-line hemofilter will increase ECMO-associated hemolysis. Circuits were configured with a Quadrox-D Adult oxygenator (surface area 1.8 m), Quadrox-iD Pediatric oxygenator (surface area 0.8 m), or Quadrox-D Adult oxygenator with an in-line hemofilter (N = 4) and ran for 6 hours. Samples were collected hourly from the ECMO circuit and a time-based hemolysis control. Plasma hemoglobin levels were assayed. Circuit-induced hemolysis at each time point was defined as the change in plasma hemoglobin standardized to the time-based hemolysis control. Plasma hemoglobin increased with the use of the smaller dimension pediatric oxygenator as compared with the adult oxygenator when controlling for ECMO run time (p = 0.02). Furthermore, there was a greater pressure gradient with the smaller dimension pediatric oxygenator (p < 0.05). Plasma hemoglobin did not change with the addition of the in-line hemofilter. The use of a smaller dimension pediatric oxygenator resulted in greater hemolysis and a higher pressure gradient. This may indicate that the increased shear forces augment ECMO-induced hemolysis. PMID:25419829

  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. Measurement of oxygen saturation in small retinal vessels with adaptive optics confocal scanning laser ophthalmoscope

    NASA Astrophysics Data System (ADS)

    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 ?m 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.

  18. 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. log pO{sub 2} is {approx} 1/5 in the p-type region, pO{sub 2} = 10{sup -5} {approx} 10{sup -1} atm. The pO{sub 2} at which the p-n transition is observed increases with increasing temperature. The activation energy for ionic conduction was estimated to be 0.86 eV from an Arrhenius plot of the minimum conductivity vs. reciprocal temperature. At temperatures below 940 C, a plateau in the conductivity isotherm suggests the presence of a two-phase region. Most likely, phase separation occurs to form a mixture of a perovskite phase and an oxygen vacancy ordered phase related to brownmillerite. Additional data for the oxygen non stoichiometry are presented.

  19. Oxygen variance and meridional oxygen supply in the Tropical North East Atlantic oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Hahn, J.; Brandt, P.; Greatbatch, R. J.; Krahmann, G.; Körtzinger, A.

    2014-12-01

    The distribution of the mean oceanic oxygen concentration results from a balance between ventilation and consumption. In the eastern tropical Pacific and Atlantic, this balance creates extended oxygen minimum zones (OMZ) at intermediate depth. Here, we analyze hydrographic and velocity data from shipboard and moored observations, which were taken along the 23°W meridian cutting through the Tropical North East Atlantic (TNEA) OMZ, to study the distribution and generation of oxygen variability. By applying the extended Osborn-Cox model, the respective role of mesoscale stirring and diapycnal mixing in producing enhanced oxygen variability, found at the southern and upper boundary of the OMZ, is quantified. From the well-ventilated equatorial region toward the OMZ core a northward eddy-driven oxygen flux is observed whose divergence corresponds to an oxygen supply of about 2.4 ?mol kg-1 year-1 at the OMZ core depth. Above the OMZ core, mesoscale eddies act to redistribute low- and high-oxygen waters associated with westward and eastward currents, respectively. Here, absolute values of the local oxygen supply >10 ?mol kg-1 year-1 are found, likely balanced by mean zonal advection. Combining our results with recent studies, a refined oxygen budget for the TNEA OMZ is derived. Eddy-driven meridional oxygen supply contributes more than 50 % of the supply required to balance the estimated oxygen consumption. The oxygen tendency in the OMZ, as given by the multidecadal oxygen decline, is maximum slightly above the OMZ core and represents a substantial imbalance of the oxygen budget reaching about 20 % of the magnitude of the eddy-driven oxygen supply.

  20. 46 CFR 197.452 - Oxygen cleaning.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Oxygen cleaning. 197.452 Section 197...of Diving Equipment § 197.452 Oxygen cleaning. The diving supervisor shall ensure that equipment used with oxygen or oxygen mixtures greater than...

  1. 46 CFR 197.452 - Oxygen cleaning.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Oxygen cleaning. 197.452 Section 197...of Diving Equipment § 197.452 Oxygen cleaning. The diving supervisor shall ensure that equipment used with oxygen or oxygen mixtures greater than...

  2. 46 CFR 197.452 - Oxygen cleaning.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Oxygen cleaning. 197.452 Section 197...of Diving Equipment § 197.452 Oxygen cleaning. The diving supervisor shall ensure that equipment used with oxygen or oxygen mixtures greater than...

  3. 46 CFR 197.452 - Oxygen cleaning.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Oxygen cleaning. 197.452 Section 197...of Diving Equipment § 197.452 Oxygen cleaning. The diving supervisor shall ensure that equipment used with oxygen or oxygen mixtures greater than...

  4. 46 CFR 197.452 - Oxygen cleaning.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Oxygen cleaning. 197.452 Section 197...of Diving Equipment § 197.452 Oxygen cleaning. The diving supervisor shall ensure that equipment used with oxygen or oxygen mixtures greater than...

  5. The Global Oxygen Cycle

    NASA Astrophysics Data System (ADS)

    Petsch, S. T.

    2003-12-01

    One of the key defining features of Earth as a planet that houses an active and diverse biology is the presence of free molecular oxygen (O2) in the atmosphere. Biological, chemical, and physical processes interacting on and beneath the Earth's surface determine the concentration of O2 and variations in O2 distribution, both temporal and spatial. In the present-day Earth system, the process that releases O2 to the atmosphere (photosynthesis) and the processes that consume O2 (aerobic respiration, sulfide mineral oxidation, oxidation of reduced volcanic gases) result in large fluxes of O2 to and from the atmosphere. Even relatively small changes in O2 production and consumption have the potential to generate large shifts in atmospheric O2 concentration within geologically short periods of time. Yet all available evidence supports the conclusion that stasis in O2 variation is a significant feature of the Earth's atmosphere over wide spans of the geologic past. Study of the oxygen cycle is therefore important because, while an equable O2 atmosphere is central to life as we know it, our understanding of exactly why O2 concentrations remain nearly constant over large spans of geologic time is very limited.This chapter begins with a review of distribution of O2 among various reservoirs on Earth's surface: air, sea, and other natural waters. The key factors that affect the concentration of O2 in the atmosphere and surface waters are next considered, focusing on photosynthesis as the major process generating free O2 and various biological and abiotic processes that consume O2. The chapter ends with a synopsis of current models on the evolution of an oxygenated atmosphere through 4.5 billion years of Earth's history, including geochemical evidence constraining ancient O2 concentrations and numerical models of atmospheric evolution.

  6. Site determination of oxygen in B6O by oxygen Kalpha x-ray-emission spectroscopy

    Microsoft Academic Search

    J. Kawai; K. Maeda; I. Higashi; M. Takami; Y. Hayasi; M. Uda

    1990-01-01

    An electron-excited x-ray-emission spectrum of oxygen Kalpha is presented for boron suboxide B6O (isostructural with B13C2). The spectrum is compared with those calculated by the discrete-variation Xalpha (DV-Xalpha) method with various O-O distances as an adjustable parameter in the fixed icosahedral B12 framework. The observed spectrum is reproduced well when the O-O distance is in the range 2.5-3.5 Å. This

  7. HYDROGEN-OXYGEN ROCKETS

    NSDL National Science Digital Library

    David Reierson

    During this activity students build a plastic pipette rocket. The first concept will to learn how igniting varying mixtures of hydrogen and oxygen will affect how far the rocket will fly. Second students will observe and manipulate variables to better understand the fundamental chemistry concepts: principles of combustion reactions, kinetics, stoichiometry, gas mixtures, rocketry, and different types of chemical reactions. Finally, students will assess their own understanding of these chemistry concepts by investigating how NASA scientists launch real rockets into space. One follow-up activity would be to investigate and collect data on a launching a heavier object at the school football field.

  8. 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. PMID:25503536

  9. Vintage Calculators Web Museum

    NSDL National Science Digital Library

    Tout, Nigel

    This "web museum" devoted to vintage calculators shows "the evolution from mechanical calculator to hand held electronic calculator." Some items featured include: Mechanical and early electronic desk calculators, "strange hand-held calculators," and articles, photographs, and databases from the archives of the International Association of Calculator Collectors. A history of the technology and information on British and sterling currency calculators are also posted here. The website also offers a Calculator time-line (chronicling calculator developments), background on the technology used by mechanical and early electronic calculators, and information on The Calculator Business. An index allows visitors to search the calculators featured on this site. The Puzzle Corner section asks visitors to contact them with any information that may answer unresolved questions regarding vintage calculators.

  10. Oxygen in GaN.

    NASA Astrophysics Data System (ADS)

    van de Walle, Chris G.; Neugebauer, Jörg

    1997-03-01

    Oxygen is commonly present during epitaxial growth of GaN. We have proposed that unintentional incorporation of O, as well as Si, is responsible for the frequently observed n-type conductivity in as-grown GaN. Here we present results from comprehensive density-functional-pseudopotential studies of GaN:O under pressure, and of O interactions with native defects and dopant impurities. We find that the O donor undergoes a DX-like transition under pressure: a large outward relaxation introduces a deep level in the band gap. This behavior explains the carrier freezeout in GaN under pressure.^1 Si donors do not exhibit the transition, consistent with experiment. Results for these impurities in AlGaN will also be discussed. We have also investigated the interaction between O and native defects. Most notably we find a large binding energy between O and the gallium vacancy (V_Ga), which we have proposed to be the source of the yellow luminescence. Finally, we have studied the interaction between O and Mg acceptors. The incorporation of the O donor is significantly enhanced in Mg-doped material. In addition, we calculate a binding energy of 0.6 eV for Mg-O complexes. The presence of O during growth can thus be detrimental to p-type GaN. ^1 C. Wetzel et al., Proc. ICPS-23 (World Scientific, Singapore, 1996), p. 2929.

  11. How patients use domiciliary oxygen.

    PubMed Central

    Jones, M M; Harvey, J E; Tattersfield, A E

    1978-01-01

    Forty-five patients in Southampton who received domiciliary oxygen were visited at home to find out how they used and coped with their oxygen. Generally, the organisation and administration of supplies presented no problems, nearly all the apparatus complied with the drug tariff, and most patients coped well with the equipment. Only two patients were taking oxygen for prescribed periods; the others were taking it when necessary for symptomatic relief. No patient received oxygen for over five hours daily. Most patients thought that they were helped by oxygen, but only four said that it allowed them to increase their level of activity, and the overall benefit seemed slight. This was partly because oxygen was usually limited to one room, so patients used oxygen after rather than during exercise. The amount of oxygen consumed differed widely, ranging from three and a half cylinders a week in three patients to less than one cylinder in six months in 17 patients. The average yearly cost of oxygen per patient ranged from 500 pounds in patients consuming one cylinder or more per week, to 15 pounds in those consuming less than one cylinder in six months. The main cost of domiciliary oxygen is determined by the number of cylinder refills, so patients who use it infrequently are a relatively small drain on resources. PMID:647308

  12. Medical oxygen and air travel.

    PubMed

    Lyznicki, J M; Williams, M A; Deitchman, S D; Howe, J P

    2000-08-01

    This report responds to a resolution that asked the American Medical Association (AMA) to take action to improve airport and airline accommodations for passengers requiring medical oxygen. Information for the report was derived from a search of the MEDLINE database and references listed in pertinent articles, as well as through communications with experts in aerospace and emergency medicine. Based on this information, the AMA Council on Scientific Affairs determined that commercial air travel exposes passengers to altitude-related hypoxia and gas expansion, which may cause some passengers to experience significant symptoms and medical complications during flight. Medical guidelines are available to help physicians evaluate and counsel potential passengers who are at increased risk of inflight hypoxemia. Supplemental oxygen may be needed for some passengers to maintain adequate tissue oxygenation and prevent hypoxemic complications. For safety and security reasons, federal regulations prohibit travelers from using their own portable oxygen system onboard commercial aircraft. Many U.S. airlines supply medical oxygen for use during flight but policies and procedures vary. Oxygen-dependent passengers must make additional arrangements for the use of supplemental oxygen in airports. Uniform standards are needed to specify procedures and equipment for the use of medical oxygen in airports and aboard commercial aircraft. Revision of federal regulations should be considered to accommodate oxygen-dependent passengers and permit them to have an uninterrupted source of oxygen from departure to destination. PMID:10954360

  13. Oxygen: Implications for Wound Healing

    PubMed Central

    Castilla, Diego M.; Liu, Zhao-Jun; Velazquez, Omaida C.

    2012-01-01

    Background Oxygen is vital for healing wounds. It is intricately involved in numerous biological processes including cell proliferation, angiogenesis, and protein synthesis, which are required for restoration of tissue function and integrity. Adequate wound tissue oxygenation can trigger healing responses and favorably influence the outcomes of other treatment modalities. The Problem Chronic ischemic wounds fail to heal appropriately secondary to extreme hypoxia that leads to cellular demise. Wound tissue hypoxia is typically greater at the center of the wound. Accordingly, oxygen requirements of the regenerating tissue will vary. Basic/Clinical Science Advances As oxygen levels decrease within the wound, cell response mechanisms (hypoxia inducible factor [HIF]) trigger the transcription of genes that promote cell survival and angiogenesis. HIF stabilizers are currently being tested to determine wound healing potential. Clinically, topical oxygen therapy (TOT) has been proved as an effective therapeutic modality for chronic wounds. TOT is reputed to have several advantages over hyperbaric oxygen therapy. Namely, TOT has a lower risk of oxygen toxicity, it is less expensive and is relatively easy to apply to target areas. Clinical Care Relevance Wound tissue oxygen is necessary for appropriate wound healing; however, the relative complexity of the healing process requires a multifaceted approach for successful healing outcomes. A key component of this multifaceted approach should be specific oxygen dosing as a function of tissue hypoxia. Conclusion New treatment approaches that exploit cell hypoxia sensing and response mechanisms and that enable the precise application of oxygen therapy to hypoxic areas of regenerating tissue are very promising. PMID:24527310

  14. Extracorporeal membrane oxygenation

    PubMed Central

    Butt, Warwick

    2013-01-01

    Extracorporeal membrane oxygenation (ECMO) is an advanced form of life support technology whereby venous blood is oxygenated outside of the body and returned to the patient. ECMO was initially used as last-resort rescue therapy for patients with severe respiratory failure. Over the last four decades, it has developed into a safe, standard therapy for newborns with progressive cardiorespiratory failure, as a resuscitation therapy after cardiac arrest, and in combination with other treatments such as hypothermia and various blood filtration therapies. ECMO has also become routine for children and adults with all forms of cardiogenic shock and is also routine in early graft failure after transplantation. The one area of ongoing debate is the role of ECMO in adults with hypoxemic respiratory failure. As ECMO equipment becomes safer, earlier use improves patient outcomes. Several modifications of the two basic venovenous and venoarterial ECMO systems are now occurring, as are many minor variations in cannulation strategies and systems of care for patients receiving ECMO. The indications and situations in which ECMO have been tried continue to change, and ECMO for sub-acute and chronic illnesses is now commonplace, as is the use of ECMO in patients with clinical problems previously regarded as contraindications, such as sepsis, malignancy, and immunosuppression. PMID:24404382

  15. 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.

  16. 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.

  17. Sterilization by oxygen plasma

    NASA Astrophysics Data System (ADS)

    Moreira, Adir José; Mansano, Ronaldo Domingues; Andreoli Pinto, Terezinha de Jesus; Ruas, Ronaldo; Zambon, Luis da Silva; da Silva, Mônica Valero; Verdonck, Patrick Bernard

    2004-07-01

    The use of polymeric medical devices has stimulated the development of new sterilization methods. The traditional techniques rely on ethylene oxide, but there are many questions concerning the carcinogenic properties of the ethylene oxide residues adsorbed on the materials after processing. Another common technique is the gamma irradiation process, but it is costly, its safe operation requires an isolated site and it also affects the bulk properties of the polymers. The use of a gas plasma is an elegant alternative sterilization technique. The plasma promotes an efficient inactivation of the micro-organisms, minimises the damage to the materials and presents very little danger for personnel and the environment. Pure oxygen reactive ion etching type of plasmas were applied to inactivate a biologic indicator, the Bacillus stearothermophilus, to confirm the efficiency of this process. The sterilization processes took a short time, in a few minutes the mortality was complete. In situ analysis of the micro-organisms' inactivating time was possible using emission spectrophotometry. The increase in the intensity of the 777.5 nm oxygen line shows the end of the oxidation of the biologic materials. The results were also observed and corroborated by scanning electron microscopy.

  18. Cerebral oxygenation and hyperthermia

    PubMed Central

    Bain, Anthony R.; Morrison, Shawnda A.; Ainslie, Philip N.

    2014-01-01

    Hyperthermia is associated with marked reductions in cerebral blood flow (CBF). Increased distribution of cardiac output to the periphery, increases in alveolar ventilation and resultant hypocapnia each contribute to the fall in CBF during passive hyperthermia; however, their relative contribution remains a point of contention, and probably depends on the experimental condition (e.g., posture and degree of hyperthermia). The hyperthermia-induced hyperventilatory response reduces arterial CO2 pressure (PaCO2) causing cerebral vasoconstriction and subsequent reductions in flow. During supine passive hyperthermia, the majority of recent data indicate that reductions in PaCO2 may be the primary, if not sole, culprit for reduced CBF. On the other hand, during more dynamic conditions (e.g., hemorrhage or orthostatic challenges), an inability to appropriately decrease peripheral vascular conductance presents a condition whereby adequate cerebral perfusion pressure may be compromised secondary to reductions in systemic blood pressure. Although studies have reported maintenance of pre-frontal cortex oxygenation (assessed by near-infrared spectroscopy) during exercise and severe heat stress, the influence of cutaneous blood flow is known to contaminate this measure. This review discusses the governing mechanisms associated with changes in CBF and oxygenation during moderate to severe (i.e., 1.0°C to 2.0°C increase in body core temperature) levels of hyperthermia. Future research directions are provided. PMID:24624095

  19. 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.

  20. Copper Proteins and Oxygen

    PubMed Central

    Frieden, Earl; Osaki, Shigemasa; Kobayashi, Hiroshi

    1965-01-01

    A comprehensive survey of the interaction of the copper proteins and oxygen is presented including a correlation of structure, function, and other properties of the known copper oxidases and of hemocyanin. The origin of their blue color and the structure of copper complexes and copper proteins are related to the oxidation state of copper ion and relevant electronic transitions probably arising from the formation of charge transfer complexes. The oxygen reactions of hemocyanin, ceruloplasmin, and cytochrome oxidase show half-saturation values far below the other Cu enzymes. The formation of hydrogen peroxide as a reaction product is associated with the presence of one Cu atom per oxidase molecule or catalytic system. Water is the corresponding product of the other Cu oxidases with four or more Cu atoms per molecule, except for monoamine oxidase. Mechanisms for the oxidase action of the two and four electron transfer Cu oxidases and tyrosinase are proposed. These reactions account for the number, the oxidation-reduction potential, and the oxidation state of Cu in the resting enzyme, the cyclical change from Cu(II) to Cu(I), the diatomic nature of O2, the sequence of the oxidation and reduction reactions, and other salient features. The catalytic reactions involved in the oxidation of ascorbic acid by plant ascorbate oxidase, ceruloplasmin, and Cu(II) are compared. Finally the substrate specificity, inhibitory control, and the detailed mechanism of the oxidase activity of ceruloplasmin are summarized. PMID:4285728

  1. High Selectivity Oxygen Delignification

    SciTech Connect

    Arthur J. Ragauskas

    2005-09-30

    The overall objective of this program was to develop improved extended oxygen delignification (EOD) technologies for current U.S. pulp mill operations. This was accomplished by: (1) Identifying pulping conditions that optimize O and OO performance; (2) Identifying structural features of lignin that enhance reactivity towards EOD of high kappa pulps; (3) Identifying factors minimizing carbohydrate degradation and improve pulp strength of EOD high kappa pulps; (4) Developing a simple, reproducible method of quantifying yield gains from EOD; and (5) Developing process conditions that significantly reduce the capital requirements of EOD while optimizing the yield benefits. Key research outcomes included, demonstrating the use of a mini-O sequence such as (E+O)Dkf:0.05(E+O) or Dkf:0.05(E+O)(E+O) without interstage washing could capture approximately 60% of the delignification efficiency of a conventional O-stage without the major capital requirements associated with an O-stage for conventional SW kraft pulps. The rate of formation and loss of fiber charge during an O-stage stage can be employed to maximize net fiber charge. Optimal fiber charge development and delignification are two independent parameters and do not parallel each other. It is possible to utilize an O-stage to enhance overall cellulosic fiber charge of low and high kappa SW kraft pulps which is beneficial for physical strength properties. The application of NIR and multi-variant analysis was developed into a rapid and simple method of determining the yield of pulp from an oxygen delignification stage that has real-world mill applications. A focus point of this program was the demonstration that Kraft pulping conditions and oxygen delignification of high and low-kappa SW and HW pulps are intimately related. Improved physical pulp properties and yield can be delivered by controlling the H-factor and active alkali charge. Low AA softwood kraft pulp with a kappa number 30 has an average improvement of 2% in yield and 4 cP in viscosity in comparison to high AA pulp for the oxygen delignification. This difference is also seen for high-kappa SW kraft pulps with an average improvement of {approx}3% in yield and 3 cP in viscosity for low AA high kappa number 50 pulp. Low AA hardwood kappa number 20 pulp had an average improvement of {approx}4% in yield and 6-12 cP in viscosity as compared to high AA pulp. Lower kraft cooking temperature (160 vs. 170 C) in combination with the medium AA provides a practical approach for integrating high kappa pulping of hardwoods (i.e., low rejects) with an advanced extended oxygen delignification stage. ECF pulp bleaching of low and high kappa kraft SW and HW pulps exhibit comparable optical and physical strength properties when bleached D(EPO)D.

  2. 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.

  3. Obesity Decreases Perioperative Tissue Oxygenation

    PubMed Central

    Kabon, Barbara; Nagele, Angelika; Reddy, Dayakar; Eagon, Chris; Fleshman, James W.; Sessler, Daniel I.; Kurz, Andrea

    2005-01-01

    Background: Obesity is an important risk factor for surgical site infections. The incidence of surgical wound infections is directly related to tissue perfusion and oxygenation. Fat tissue mass expands without a concomitant increase in blood flow per cell, which might result in a relative hypoperfusion with decreased tissue oxygenation. Consequently, we tested the hypotheses that perioperative tissue oxygen tension is reduced in obese surgical patients. Furthermore, we compared the effect of supplemental oxygen administration on tissue oxygenation in obese and non-obese patients. Methods: Forty-six patients undergoing major abdominal surgery were assigned to one of two groups according to their body mass index (BMI): BMI < 30 kg/m2 (non-obese) and BMI ? 30 kg/m2 (obese). Intraoperative oxygen administration was adjusted to arterial oxygen tensions of ?150 mmHg and ?300 mmHg in random order. Anesthesia technique and perioperative fluid management were standardized. Subcutaneous tissue oxygen tension was measured with a polarographic electrode positioned within a subcutaneous tonometer in the lateral upper arm during surgery, in the recovery room, and on the first postoperative day. Postoperative tissue oxygen was also measured adjacent to the wound. Data were compared with unpaired two tailed t-tests and Wilcoxon rank-sum tests; P < 0.05 was considered statistically significant. Results: Intraoperative subcutaneous tissue oxygen tension was significantly less in the obese patients at baseline (36 vs. 57 mmHg, P = 0.002) and with supplemental oxygen administration (47 vs. 76 mmHg, P = 0.014). Immediate postoperative tissue oxygen tension was also significantly less in subcutaneous tissue of the upper arm (43 vs. 54 mmHg, P = 0.011) as well as near the incision (42 vs. 62 mmHg, P = 0.012) in obese patients. In contrast, tissue oxygen tension was comparable in each group on the first postoperative morning. Conclusion: Wound and tissue hypoxia were common in obese patients in the perioperative period and most pronounced during surgery. Even with supplemental oxygen tissue, oxygen tension in obese patients was reduced to levels that are associated with a substantial increase in infection risk. Summary Statement: Wound and tissue hypoxia were both common in obese patients in the perioperative period and most pronounced during surgery. Supplemental oxygen only slightly increased tissue oxygenation in obese patients. PMID:14739800

  4. Outgassing of oxygen from polycarbonate.

    PubMed

    Moon, Sung In; Monson, L; Extrand, C W

    2009-07-01

    A manometric permeation apparatus was used to study the "outgassing" or desorption of oxygen from polycarbonate (PC). A PC film was placed in the apparatus. Both sides were exposed to oxygen until the film was saturated. To simulate inert gas purging of a closed container or "microenvironment", oxygen was pumped from one side of the apparatus to reduce the concentration on that side to nearly zero. Oxygen concentrations on the freshly purged side rose quickly at first but then slowed. Eventually, a steady state was established and oxygen concentrations increased linearly with time. Mass-transport coefficients (permeation, diffusion, and solubility coefficients) were also estimated and then used to successfully predict the postpurge rise of the oxygen concentration. PMID:20355958

  5. Oxygen abundance in the Sloan Digital Sky Survey

    E-print Network

    F. Shi; X. Kong; F. Z. Cheng

    2006-03-10

    We present two samples of $\\hii$ galaxies from the Sloan Digital Sky Survey (SDSS) spectroscopic observations data release 3. The electron temperatures($T_e$) of 225 galaxies are calculated with the photoionized $\\hii$ model and $T_e$ of 3997 galaxies are calculated with an empirical method. The oxygen abundances from the $T_e$ methods of the two samples are determined reliably. The oxygen abundances from a strong line metallicity indicator, such as $R_{23}$, $P$, $N2$, and $O3N2$, are also calculated. We compared oxygen abundances of $\\hii$ galaxies obtained with the $T_e$ method, $R_{23}$ method, $P$ method, $N2$ method, and $O3N2$method. The oxygen abundances derived with the $T_e$ method are systematically lower by $\\sim$0.2 dex than those derived with the $R_{23}$ method, consistent with previous studies based on $\\hii$ region samples. No clear offset for oxygen abundance was found between $T_e$ metallicity and $P$, $N2$ and $O3N2$ metallicity. When we studied the relation between N/O and O/H, we found that in the metallicity regime of $\\zoh > 7.95$, the large scatter of the relation can be explained by the contribution of small mass stars to the production of nitrogen. In the high metallicity regime, $\\zoh > 8.2$, nitrogen is primarily a secondary element produced by stars of all masses.

  6. Two photon excitation of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Pindzola, M. S.

    1977-01-01

    A standard perturbation expansion in the atom-radiation field interaction is used to calculate the two photon excitation cross section for 1s(2) 2s(2) 2p(4) p3 to 1s(2) 2s(2) 2p(3) (s4) 3p p3 transition in atomic oxygen. The summation over bound and continuum intermediate states is handled by solving the equivalent inhomogeneous differential equation. Exact summation results differ by a factor of 2 from a rough estimate obtained by limiting the intermediate state summation to one bound state. Higher order electron correlation effects are also examined.

  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, measurements of the chemical and thermal expansion as a function of temperature and p{sub O2} are described.

  8. 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.

  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. 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.

  11. Electrochemical studies of quinone oxygen

    SciTech Connect

    Deanhardt, M.L. (Lander College, Greenwood, SC (US)); Mushrush, G.W.; Stalick, W.M. (Chemistry Dept., George mason Univ., Fairfax, VA (US)); Watkins, J.M. Jr. (Naval Research Lab., Fuels Section, Code 6180, Washington, DC (US))

    1990-02-01

    Asphaltenes are a chemically complex mixture of aromatic and heteroaromatic compounds. This material contains oxygen in various functional groups. The distribution includes esters, carboxylic acids, phenolic and most probably quinone type oxygen functionalities. The present work details the complete electrochemical behaviour of quinone type oxygen. The method is quinone specific. A condensed aromatic quinone, 9,10-anthraquinone, was selected as representative of complex quinones. By this method quinones can be determined in the presence of other oxygen functional groups, alcohols, carboxylic acids, ethers, and other carbonyls.

  12. LDEF atomic oxygen fluence update

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    The definition of LDEF atomic oxygen exposure involves theoretical prediction of fluxes, modeling of shielding and scattering effects, and comparison of predicted with observed atomic oxygen effects on LDEF experiments. Work is proceeding as follows: atomic oxygen fluxes and fluences have been recalculated using a more detailed orbit prediction program; a micro-environments program is being developed to account for the effects of experiment geometry on atomic oxygen flux; and chemical and physical measurements are being made on copper grounding straps to verify correspondence between predicted exposures and observed surface property variations. These three areas of work are reported briefly.

  13. Mass spectrometers and atomic oxygen

    NASA Technical Reports Server (NTRS)

    Hunton, D. E.; Trzcinski, E.; Cross, J. B.; Spangler, L. H.; Hoffbauer, M. H.; Archuleta, F. H.; Visentine, J. T.

    1987-01-01

    The likely role of atmospheric atomic oxygen in the recession of spacecraft surfaces and in the shuttle glow has revived interest in the accurate measurement of atomic oxygen densities in the upper atmosphere. The Air Force Geophysics Laboratory is supplying a quadrupole mass spectrometer for a materials interactions flight experiment being planned by the Johnson Space Center. The mass spectrometer will measure the flux of oxygen on test materials and will also identify the products of surface reactions. The instrument will be calibrated at a new facility for producing high energy beams of atomic oxygen at the Los Alamos National Laboratory. The plans for these calibration experiments are summarized.

  14. Inexpensive low-oxygen incubators.

    PubMed

    Wright, Woodring E; Shay, Jerry W

    2006-01-01

    Although the evidence is overwhelming that ambient oxygen is at least somewhat damaging to most normal cells in culture, the expense and effort involved has resulted in few laboratories growing their cells under physiological oxygen conditions. We here describe how to produce, from commercially available plastic wide-mouth jars, very simple gas-tight containers that can be flushed with prepared gas mixtures to produce low-oxygen environments for standard cell culture. This permits any laboratory to easily try the effects of physiological oxygen on their system without the need for dedicated incubators and substantial monetary investments. PMID:17487199

  15. 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.

  16. Clinical oxygen enhancement ratio of tumors in carbon ion radiotherapy: the influence of local oxygenation changes

    PubMed Central

    Antonovic, Laura; Lindblom, Emely; Dasu, Alexandru; Bassler, Niels; Furusawa, Yoshiya; Toma-Dasu, Iuliana

    2014-01-01

    The effect of carbon ion radiotherapy on hypoxic tumors has recently been questioned because of low linear energy transfer (LET) values in the spread-out Bragg peak (SOBP). The aim of this study was to investigate the role of hypoxia and local oxygenation changes (LOCs) in fractionated carbon ion radiotherapy. Three-dimensional tumors with hypoxic subvolumes were simulated assuming interfraction LOCs. Different fractionations were applied using a clinically relevant treatment plan with a known LET distribution. The surviving fraction was calculated, taking oxygen tension, dose and LET into account, using the repairable–conditionally repairable (RCR) damage model with parameters for human salivary gland tumor cells. The clinical oxygen enhancement ratio (OER) was defined as the ratio of doses required for a tumor control probability of 50% for hypoxic and well-oxygenated tumors. The resulting OER was well above unity for all fractionations. For the hypoxic tumor, the tumor control probability was considerably higher if LOCs were assumed, rather than static oxygenation. The beneficial effect of LOCs increased with the number of fractions. However, for very low fraction doses, the improvement related to LOCs did not compensate for the increase in total dose required for tumor control. In conclusion, our results suggest that hypoxia can influence the outcome of carbon ion radiotherapy because of the non-negligible oxygen effect at the low LETs in the SOBP. However, if LOCs occur, a relatively high level of tumor control probability is achievable with a large range of fractionation schedules for tumors with hypoxic subvolumes, but both hyperfractionation and hypofractionation should be pursued with caution. PMID:24728013

  17. Oxygen dynamics around buried lesser sandeels Ammodytes tobianus (Linnaeus 1785): mode of ventilation and oxygen requirements.

    PubMed

    Behrens, Jane W; Stahl, Henrik J; Steffensen, John F; Glud, Ronnie N

    2007-03-01

    The oxygen environment around buried sandeels (Ammodytes tobianus) was monitored by planar optodes. The oxygen penetration depth at the sediment interface was only a few mm. Thus fish, typically buried at 1-4 cm depth, were generally in anoxic sediment. However, they induced an advective transport through the permeable interstice and formed an inverted cone of porewater with 93% air saturation in front of the mouth. From dye experiments the mean ventilatory flow rate was estimated at 0.26+/-0.02 ml min(-1) (86.9+/-7.3 ml min(-1) kg(-1)) (N=3). Expelled water from the gills induced a 1 cm circular plume with <15% air saturation around the gills. During this quasi-steady ventilation mode, fish extracted 86.2+/-4.8% (N=7) of the oxygen from the inspired water. However, 13% of the investigated fish (2 of 15) occasionally wriggled their bodies and thereby transported almost fully air-saturated water down along the body, referred to as ;plume ventilation'. Yet, within approximately 30 min the oxic plume was replenished by oxygen-depleted water from the gills. The potential for cutaneous respiration by the buried fish was thus of no quantitative importance. Calculations derived by three independent methods (each with N=3) revealed that the oxygen uptake of sandeel buried for 6-7 h was 40-50% of previous estimates on resting respirometry of non-buried fish, indicating lower O(2) requirements during burial on a diurnal timescale. Buried fish exposed to decreasing oxygen tensions gradually approached the sediment surface, but remained in the sediment until the inspired water reached 5-10% air saturation. PMID:17337713

  18. 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.

  19. 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…

  20. 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.

  1. 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

    A viewgraph presentation evaluating the compatibility of oxygen components and systems is shown. The topics include: 1) Application; 2) Gaining Wide Subscription; 3) Approach; 4) Establish Worst-Case Operating Conditions; 5) Assess Materials Flammability; 6) Evaluate Ignition Mechanisms; 7) Evaluate Kindling Chain; 8) Determine Reaction Affect; 9) Document Results; 10) Example of Documentation; and 11) Oxygen Compatibility Assessment Team.

  2. DIAGENETIC OXYGEN EQUIVALENTS MODEL OF SEDIMENT OXYGEN DEMAND

    EPA Science Inventory

    The consumption of oxygen in the overlying water by sediments is an important component in the oxygen balance of most natural waters. Conventional practice is to specify the magnitude of this sink using direct uptake measurements. Unfortunately, if the management alternative bein...

  3. Capillary-oxygenation-level-dependent near-infrared spectrometry in frontal lobe of humans

    Microsoft Academic Search

    Peter Rasmussen; Ellen A Dawson; Lars Nybo; Johannes J van Lieshout; Niels H Secher; Albert Gjedde

    2007-01-01

    Brain function requires oxygen and maintenance of brain capillary oxygenation is important. We evaluated how faithfully frontal lobe near-infrared spectroscopy (NIRS) follows haemoglobin saturation (SCap) and how calculated mitochondrial oxygen tension (PMitoO2) influences motor performance. Twelve healthy subjects (20 to 29 years), supine and seated, inhaled O2 air-mixtures (10% to 100%) with and without added 5% carbon dioxide and during

  4. First principles study of oxygen-deficient centers in pure and Ge-doped silica

    Microsoft Academic Search

    N. Richard; S. Girard; L. Martin-Samos; V. Cuny; A. Boukenter; Y. Ouerdane; J.-P. Meunier

    2011-01-01

    Using ab initio calculations on 108 atoms pure- and Ge-doped (2.8mol%) silica-based supercells, we performed a statistical study on the electronic structure and energetic contribution of neutral oxygen vacancies, also named Oxygen Deficient Centers (ODCs). All the 72 oxygen sites in the amorphous silica (a-SiO2) cell were considered as possible candidates for the formation of the vacancies leading to study

  5. Oxygen-sulfur exchange and the gas-phase reactivity of cobalt sulfide cluster anions with molecular oxygen.

    PubMed

    Jia, Mei-Ye; Luo, Zhixun; He, Sheng-Gui; Ge, Mao-Fa

    2014-09-18

    We present here a study of gas-phase reactivity of cobalt sulfide cluster anions Co(m)S(n)(-) with molecular oxygen. Nascent Co(m)S(n)(-) clusters were prepared via a laser ablation source and reacted with oxygen in a fast flow reactor under thermal collision conditions. We chose (18)O2 in place of (16)O2 to avoid mass degeneration with sulfur, and a time-of-flight (TOF) mass spectrometer was used to detect the cluster distributions in the absence and presence of the reactant. It was found that oxygen-sulfur exchange occurs in the reactions for those with specific compositions (CoS)(n)(-) and (CoS)(n)S(-) (n = 2-5) according to a consistent pathway, "Co(m)S(n)(-) + (18)O2 ? Co(m)S(n-1)(18)O(-) + S(18)O". Typically, for "Co2S2(-) + (18)O2" we have calculated the reaction coordinates by employing the density functional theory (DFT), where both the oxygen-sulfur exchange and SO molecule release are thermodynamically and kinetically favorable. It is noteworthy that the reaction with molecular oxygen (triplet ground state) needs to overcome a spin excitation as well as a large O-O activation energy. This study sheds light on the activation of molecular oxygen by cobalt sulfides on one hand and also provides insight into the regeneration mechanism of cobalt oxides from the counterpart sulfides in the presence of oxygen gas on the other hand. PMID:24588651

  6. Isotopic exchange between the oxygen of a solid oxide electrolyte based on ZrO/sub 2/ and gaseous oxygen

    SciTech Connect

    Kurumchin, E.K.; Ishchuk, V.P.

    1983-02-01

    The rate of heteroexchange of oxygen of the electrolyte 0.906ZrO/sub 2/ + 0.094Sc/sub 2/O/sub 3/ in an atmosphere of free oxygen at the temperature 700-850/sup 0/C and oxygen pressure 10-40 mm Hg was measured by the method of isotopic exchange of oxygen using the isotope /sup 18/O. The rate of homoexchange of oxygen, the activation energies of the reactions of homo- and heteroexchange, the values of the orders of the dependence of the rates of these reactions on the oxygen pressure, as well as the contributions of various types of exchange to the total rate, were calculated. The characteristics of exchange obtained were compared with those for an electrolyte with composition 0.9ZrO/sub 2/ + 0.1Y/sub 2/O/sub 3/. Reversible dissociative adsorption and desorption of oxygen is suggested as the limiting steps of heteroexchange.

  7. 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.

  8. Autistic Savant Calendar Calculators.

    ERIC Educational Resources Information Center

    Patti, Paul J.

    This study identified 10 savants with developmental disabilities and an exceptional ability to calculate calendar dates. These "calendar calculators" were asked to demonstrate their abilities, and their strategies were analyzed. The study found that the ability to calculate dates into the past or future varied widely among these calculators. Three…

  9. Oxygen on an Fe monolayer on W(110): From chemisorption to oxidation?

    PubMed Central

    Freindl, K.; Partyka-Jankowska, E.; Kara?, W.; Zaj?c, M.; Madej, E.; Spiridis, N.; ?l?zak, M.; ?l?zak, T.; Wi?nios, D.; Korecki, J.

    2013-01-01

    The adsorption of oxygen on a pseudomorphic iron monolayer deposited on a W(110) surface was studied experimentally and theoretically. Standard surface characterization methods, such as Auger electron spectroscopy and low energy electron diffraction, and specific nuclear methods, such as conversion electron Mössbauer spectroscopy (CEMS) and nuclear resonant scattering of synchrotron radiation, combined with theoretical calculations based on the density functional theory allowed us to determine the structure of the oxygen adsorbate and the electronic properties of iron atoms with different oxygen coordinations. The oxygen-(3 × 2) structure on the iron monolayer was recognized and was interpreted to be a state with oxygen chemisorbed on the non-reconstructed surface with modest electron transfer from iron to oxygen. A transition from chemisorbed oxygen to the onset of Fe-oxidation is revealed by distinct changes in the CEMS spectra. PMID:24748690

  10. Voice over IP Calculator

    NSDL National Science Digital Library

    The Voice over IP Calculator Web site actually consists of four free online tools that can be used to estimate bandwidth requirements and voice paths for a planned VoIP system. The four tools are: Lines and IP Bandwidth Calculator, Erlangs and Bandwidth Calculator, Minutes and Lines Calculator, and Erlangs and Lines Calculator. Each utility is very easy to use, but is mainly intended for experienced IT workers.

  11. 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 ?17O versus ?18O. 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 et al., 1996). In their paper reporting the discovery of 18O in the Earth's atmosphere, Giauque and Johnston (1929) refer to nonuniform distribution of oxygen isotopes as a "remote possibility," whereas Manian et al. (1934) sought to find variations in oxygen isotope abundances in meteorites as evidence for an origin outside the solar system.In addition to the abundance variations due to nuclear processes, there are important isotopic variations produced within molecular clouds, the precursors to later star-formation. The most important process is isotopic self-shielding in the UV photodissociation of CO (van Dishoeck and Black, 1988). This process results from the large differences in abundance between C16O, on the one hand, and C17O and C18O on the other. Photolysis of CO occurs by absorption of stellar UV radiation in the wavelength range 90-100 nm. The reaction proceeds by a predissociation mechanism, in which the excited electronic state lives long enough to have well-defined vibrational and rotational energy levels. As a consequence, the three isotopic species - C16O, C17O, and C18O - absorb at different wavelengths, corresponding to the isotope shift in vibrational frequencies. Because of their different number densities, the abundant C16O becomes optically thick in the outermost part of the cloud (nearest to the external source of UV radiation), while the rare C17O and C18O remain optically thin, and hence dissociate at a greater rate in the cloud interior. The differences in chemical reactivity between C16O molecules and 17O and 18O atoms may lead to isotopically selective reaction products. This scenario has been suggested to explain meteoritic isotope patterns, as discussed below (Yurimoto and Kuramoto, 2002).Stable isotope abundances in meteoritic material provide an opportunity to evaluate the thoroughness of mixing of isotopes of diverse stellar sources. Molybdenum presents a good test case: it has seven stable isotopes, derived from at least three types of stellar sources, corresp

  12. Novel Membranes and Processes for Oxygen Enrichment

    SciTech Connect

    Lin, Haiqing

    2011-11-15

    The overall goal of this project is to develop a membrane process that produces air containing 25-35% oxygen, at a cost of $25-40/ton of equivalent pure oxygen (EPO2). Oxygen-enriched air at such a low cost will allow existing air-fueled furnaces to be converted economically to oxygen-enriched furnaces, which in turn will improve the economic and energy efficiency of combustion processes significantly, and reduce the cost of CO{sub 2} capture and sequestration from flue gases throughout the U.S. manufacturing industries. During the 12-month Concept Definition project: We identified a series of perfluoropolymers (PFPs) with promising oxygen/nitrogen separation properties, which were successfully made into thin film composite membranes. The membranes showed oxygen permeance as high as 1,200 gpu and oxygen/nitrogen selectivity of 3.0, and the permeance and selectivity were stable over the time period tested (60 days). We successfully scaled up the production of high-flux PFP-based membranes, using MTR's commercial coaters. Two bench-scale spiral-wound modules with countercurrent designs were made and parametric tests were performed to understand the effect of feed flow rate and pressure, permeate pressure and sweep flow rate on the membrane module separation properties. At various operating conditions that modeled potential industrial operating conditions, the module separation properties were similar to the pure-gas separation properties in the membrane stamps. We also identified and synthesized new polymers [including polymers of intrinsic microporosity (PIMs) and polyimides] with higher oxygen/nitrogen selectivity (3.5-5.0) than the PFPs, and made these polymers into thin film composite membranes. However, these membranes were susceptible to severe aging; pure-gas permeance decreased nearly six-fold within two weeks, making them impractical for industrial applications of oxygen enrichment. We tested the effect of oxygen-enriched air on NO{sub x} emissions using a Bloom baffle burner at GTI. The results are positive and confirm that oxygen-enriched combustion can be carried out without producing higher levels of NOx than normal air firing, if lancing of combustion air is used and the excess air levels are controlled. A simple economic study shows that the membrane processes can produce O{sub 2} at less than $40/ton EPO{sub 2} and an energy cost of 1.1-1.5 MMBtu/ton EPO{sub 2}, which are very favorable compared with conventional technologies such as cryogenics and vacuum pressure swing adsorption processes. The benefits of integrated membrane processes/combustion process trains have been evaluated, and show good savings in process costs and energy consumption, as well as reduced CO{sub 2} emissions. For example, if air containing 30% oxygen is used in natural gas furnaces, the net natural gas savings are an estimated 18% at a burner temperature of 2,500 F, and 32% at a burner temperature of 3,000 F. With a 20% market penetration of membrane-based oxygen-enriched combustion in all combustion processes by 2020, the energy savings would be 414-736 TBtu/y in the U.S. The comparable net cost savings are estimated at $1.2-2.1 billion per year by 2020, calculated as the value of fuel savings subtracted from the cost of oxygen production. The fuel savings of 18%-32% by the membrane/oxygen-enriched combustion corresponds to an 18%-32% reduction in CO{sub 2} emissions, or 23-40 MM ton/y less CO{sub 2} from natural gas-fired furnaces by 2020. In summary, results from this project (Concept Definition phase) are highly promising and clearly demonstrate that membrane processes can produce oxygen-enriched air in a low cost manner that will lower operating costs and energy consumption in industrial combustion processes. Future work will focus on proof-of-concept bench-scale demonstration in the laboratory.

  13. Oxygen isotope fractionation between oxygen of different sites in illite minerals: a potential single-mineral thermometer

    NASA Astrophysics Data System (ADS)

    Bechtel, A.; Hoernes, S.

    1990-07-01

    The experimental results of Hamza and Epstein mark internal oxygen isotope fractionations of hydrosilicates as potential single-mineral thermometers. In this study methodical investigations were made to determine the oxygen isotope ratios of hydroxyl groups in silicate minerals. As a reference material a commercial kaolinite was examined by vacuum extraction and by use of a modified partial fluorination technique first deseribed by Hamza and Epstein. The concordance of the results argue against oxygen isotope fractionation during dehydroxylation. Consequently, vacuum extraction can be used to determine the internal fractionation of minerals, which contain no ferrous iron. For calibration of the internal oxygen isotope fractionation, hydrothermally formed illites from the “Lone Gull” uranium deposit in Canada and from the “Leuggern” exploration drill site in Switzerland were investigated. Formation temperatures of the hydrothermal mineralization were estimated by mineral paragenesis, illite crystallinity and by oxygen isotope fractionations on coexisting mineral phases. the oxygen isotope fractionation between oxygen of different sites in several selected illites from both regions has been analysed. The results indicate a linear correlation between the illite-OH oxygen isotope fractionation and temperature. The fractionation can be expressed by the following equation: 410_2005_Article_BF01575623_TeX2GIFE1.gif 1000ln ? _{left( {ill - OH} right)} = - 0.076t + 30.42 ( i equals temperature in °C). Using this first calibration of the illite-OH fractionation, it is possible to determine formation temperatures of hydrothermal mineral assemblages. To test the calibration curve, the internal fractionation of an illite sample from the Nama-Series (Namibia) was measured. The temperature calculated from the determined fractionation is in agreement with estimates from mineral paragenesis and illite crystallinity. Concordant illite-OH fractionations have also been calculated by use of the increment method according to Schütze.

  14. The role of oxygen and water on molybdenum nanoclusters for electro catalytic ammonia production

    PubMed Central

    Howalt, Jakob G

    2014-01-01

    Summary The presence of water often gives rise to oxygen adsorption on catalyst surfaces through decomposition of water and the adsorbed oxygen or hydroxide species often occupy important surfaces sites, resulting in a decrease or a total hindrance of other chemical reactions taking place at that site. In this study, we present theoretical investigations of the influence of oxygen adsorption and reduction on pure and nitrogen covered molybdenum nanocluster electro catalysts for electrochemical reduction of N2 to NH3 with the purpose of understanding oxygen and water poisoning of the catalyst. Density functional theory calculations are used in combination with the computational hydrogen electrode approach to calculate the free energy profile for electrochemical protonation of O and N2 species on cuboctahedral Mo13 nanoclusters. The calculations show that the molybdenum nanocluster will preferentially bind oxygen over nitrogen and hydrogen at neutral bias, but under electrochemical reaction conditions needed for nitrogen reduction, oxygen adsorption is severely weakened and the adsorption energy is comparable to hydrogen and nitrogen adsorption. The potentials required to reduce oxygen off the surface are ?0.72 V or lower for all oxygen coverages studied, and it is thus possible to (re)activate (partially) oxidized nanoclusters for electrochemical ammonia production, e.g., using a dry proton conductor or an aqueous electrolyte. At lower oxygen coverages, nitrogen molecules can adsorb to the surface and electrochemical ammonia production via the associative mechanism is possible at potentials as low as ?0.45 V to ?0.7 V. PMID:24605277

  15. Monitor hemoglobin concentration and oxygen saturation in living mouse tail using photoacoustic CT scanner

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Kruger, Robert; Reinecke, Daniel; Stantz, Keith M.

    2010-02-01

    Purpose: The purpose of this study is to use PCT spectroscopy scanner to monitor the hemoglobin concentration and oxygen saturation change of living mouse by imaging the artery and veins in a mouse tail. Materials and Methods: One mouse tail was scanned using the PCT small animal scanner at the isosbestic wavelength (796nm) to obtain its hemoglobin concentration. Immediately after the scan, the mouse was euthanized and its blood was extracted from the heart. The true hemoglobin concentration was measured using a co-oximeter. Reconstruction correction algorithm to compensate the acoustic signal loss due to the existence of bone structure in the mouse tail was developed. After the correction, the hemoglobin concentration was calculated from the PCT images and compared with co-oximeter result. Next, one mouse were immobilized in the PCT scanner. Gas with different concentrations of oxygen was given to mouse to change the oxygen saturation. PCT tail vessel spectroscopy scans were performed 15 minutes after the introduction of gas. The oxygen saturation values were then calculated to monitor the oxygen saturation change of mouse. Results: The systematic error for hemoglobin concentration measurement was less than 5% based on preliminary analysis. Same correction technique was used for oxygen saturation calculation. After correction, the oxygen saturation level change matches the oxygen volume ratio change of the introduced gas. Conclusion: This living mouse tail experiment has shown that NIR PCT-spectroscopy can be used to monitor the oxygen saturation status in living small animals.

  16. Waiting ages for atmospheric oxygen: A titration hourglass and the oxidation of the solid Earth. (Invited)

    NASA Astrophysics Data System (ADS)

    Catling, D. C.; Claire, M.; Zahnle, K. J.

    2013-12-01

    Atmospheric O2 increased from less than 1 ppm to 0.2-2% at 2.45-2.22 Ga in the Great Oxidation Event (GOE). A minority opinion is that the GOE happened close to the time when oxygenic photosynthesis originated but evidence from the concentration of redox-sensitive elements in shales and their isotopes, as well as the setting and morphology of stromatolites supports the consensus view that oxygenic photosynthesis had originated by 2.8-2.7 Ga. Models show that O2 can be consumed rapidly by reductants in the Archean so that the air can remain anoxic even after photosynthesis began pumping out O2. Why did the world ultimately shift away from this balance? What conditions were needed to oxygenate the atmosphere in addition to oxygenic photosynthesis? A general principle is that a shift to an oxic environment from a reducing one requires net export of reductant. In planetary science, for example, the oxidation of the surfaces and atmospheres of other planets or satellites is universally attributed to the escape of hydrogen to space. Hydrogen escape explains the redness of Mars, several characteristics of the atmosphere of Venus, and the presence of tenuous O2 atmospheres on Ganymede, Europa, Rhea and Dione. For the Earth's rise of oxygen, many ideas focus on a decline in mantle or seafloor reductant fluxes (driven by internal geologic evolution) to the point where these fluxes were surpassed by biogenic oxygen fluxes. But for such a shift (without a role for hydrogen escape), the surface still has to export net reductant to the mantle. Such net export depends on the ratio of subducted ferric iron versus reduced carbon during the Archean, which remains poorly constrained. Over a decade ago, we proposed that rapid escape of hydrogen to space from the pre-GOE atmosphere would have gradually oxidized the Earth's surface and crust, accompanied by falling levels of atmospheric CH4 [1]. The idea is that Earth underwent a redox titration. A point would be reached where O2 became more stable than competing reducing gases, such as CH4 and H2. In this scheme, the delay in the rise of oxygen by several hundred million years is the time it takes to oxidize the outer portions of the solid Earth to the point when the atmosphere flipped redox state. We also speculate that hydrogen escape may be associated with continental growth. As the Archean continents grew, they would have accumulated excess oxygen in their minerals at the tempo of hydrogen escape. The ferric oxide concentration in average continents is an order of magnitude greater than in the mantle. Continental growth supplied reducing power to the surface environment that became intertwined with the carbon cycle and photosynthesis. Thus, 'granitoid' material may be a consequence of increased oxygen fugacity in weathered subducted materials (cf. ref. 2). If so, continents are, in part, a response to surface oxidation rather than vice versa. Moreover, continental growth would necessarily slow once hydrogen escape rates were throttled by the GOE. [1] Catling et al. (2001) Science 293, 839 [2] Jagoutz (2013) Terra Nova 25, 95

  17. 9, 140, 2009 Oxygenated organic

    E-print Network

    Russell, Lynn

    campaign S. Liu 1 , S. Takahama 1 , L. M. Russell 1 , S. Gilardoni 1,2 , and D. Baumgardner 3 1 ScrippsACPD 9, 1­40, 2009 Oxygenated organic aerosol in MILAGRO S. Liu et al. Title Page Abstract of the European Geosciences Union. 1 #12;ACPD 9, 1­40, 2009 Oxygenated organic aerosol in MILAGRO S. Liu et al

  18. Mars oxygen production system design

    NASA Technical Reports Server (NTRS)

    Cotton, Charles E.; Pillow, Linda K.; Perkinson, Robert C.; Brownlie, R. P.; Chwalowski, P.; Carmona, M. F.; Coopersmith, J. P.; Goff, J. C.; Harvey, L. L.; Kovacs, L. A.

    1989-01-01

    The design and construction phase is summarized of the Mars oxygen demonstration project. The basic hardware required to produce oxygen from simulated Mars atmosphere was assembled and tested. Some design problems still remain with the sample collection and storage system. In addition, design and development of computer compatible data acquisition and control instrumentation is ongoing.

  19. The Biology of Oxygen Radicals

    Microsoft Academic Search

    Irwin Fridovich

    1978-01-01

    The reactive superoxide radical, O2{}-, formerly of concern only to radiation chemists and radiobiologists, is now understood to be a normal product of the biological reduction of molecular oxygen. An unusual family of enzymes, the superoxide dismutases, protect against the deleterious actions of this radical by catalyzing its dismutation to hydrogen peroxide plus oxygen.

  20. ANALYTICAL METHODS FOR FUEL OXYGENATES

    EPA Science Inventory

    MTBE (and potentially any other oxygenate) may be present at any petroleum UST site, whether the release is new or old, virtually anywhere in the United States. Consequently, it is prudent to analyze samples for the entire suite of oxygenates as identified in this protocol (i.e....

  1. How to Measure Dissolved Oxygen

    NSDL National Science Digital Library

    This web page, hosted by the Washington State Department of Ecology, offers a general overview of dissolved oxygen and how it is measured. It includes protocols for measuring dissolved oxygen in turbulent waters as well as using the Winkler titration method. The site also features links to measuring other water quality parameters such as pH, nutrients, and turbidity.

  2. Global climatic interpretation of the deuterium-oxygen 18 relationship for precipitation

    Microsoft Academic Search

    Liliane Merlivat; Jean Jouzel

    1979-01-01

    A theoretical model is derived to account for the deuterium-oxygen 18 relationship measured in meteorice waters. A steady state regime is assumed for the evaporation of water at the ocean surface and the subsequent formation of precipitation. The calculations show that the deuterium and oxygen 18 content in precipitation can be taken as linearly related. From the slope and the

  3. A 12-kW continuous-wave chemical oxygen-iodine laser

    SciTech Connect

    Boreysho, A S; Mal'kov, V M; Savin, Aleksandr V; Vasil'ev, D N; Evdokimov, I M; Trilis, A V; Strakhov, S Yu [Institute of Laser Instruments and Technologies, D F Ustinov 'VOENMEKh' Baltic State Technical University, St Petersburg (Russian Federation)

    2003-04-30

    A 12-kW continuous-wave chemical oxygen-iodine laser, provided with an original jet-type singlet oxygen generator, is developed and tested. The experimental and numerical techniques applied for the diagnostics and mathematical simulation of processes in the laser active medium are introduced. Some of the calculation and experimental results are presented. (lasers)

  4. A New Method of measuring Oxygen consumed in the Metabolism of Small Animals

    Microsoft Academic Search

    V. Capraro

    1953-01-01

    THE principle of replacing, by means of electrolysis, the oxygen consumed in measurements of metabolism offers the threefold possibility of having a high degree of sensitivity, of controlling the phenomenon for an unlimited time and avoiding calculation entirely. An electrolytic cell (30 per cent sodium hydroxide), capable of producing oxygen, is connected by means of a tube to the thermostatic

  5. Influence of strain and oxygen vacancies on the magnetoelectric properties of multiferroic bismuth ferrite

    Microsoft Academic Search

    Claude Ederer; Nicola A. Spaldin

    2005-01-01

    The dependencies on strain and oxygen vacancies of the ferroelectric polarization and the weak ferromagnetic magnetization in the multiferroic material bismuth ferrite, BiFeO3 , are investigated using first principles density functional theory calculations. The electric polarization is found to be rather independent of strain, in striking contrast to most conventional perovskite ferroelectrics. It is also not significantly affected by oxygen

  6. 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.

  7. Research on rechargeable oxygen electrodes

    NASA Technical Reports Server (NTRS)

    Giner, J.; Malachesky, P. A.; Holleck, G.

    1971-01-01

    Studies were carried out on a number of factors which may influence the behavior of the platinum electrocatalyst of oxygen electrodes for use in rechargeable metal-oxygen batteries or hydrogen-oxygen fuel cells. The effects of pretreatments for various potentials and added ionic species, which could be present in such systems, were studied with reguard to: (1) the state of surface oxidation, (2) platinum dissolution, (3) the kinetics of oxygen evolution and reduction (including the role of hydrogen peroxide), and (4) changes in porous electrode structure. These studies were carried out on smooth platinum, platinized platinum, and Teflon-bonded platinum black electrodes in carefully purified electrolyte solutions. The main factors which appear to affect rechargeable oxygen electrode performance and life are: (1) the buildup of a refractory anodic layer on extended cycling, and (2) the dissolution of platinum.

  8. Oxygen detection using evanescent fields

    DOEpatents

    Duan, Yixiang (Los Alamos, NM); Cao, Weenqing (Los Alamos, NM)

    2007-08-28

    An apparatus and method for the detection of oxygen using optical fiber based evanescent light absorption. Methylene blue was immobilized using a sol-gel process on a portion of the exterior surface of an optical fiber for which the cladding has been removed, thereby forming an optical oxygen sensor. When light is directed through the optical fiber, transmitted light intensity varies as a result of changes in the absorption of evanescent light by the methylene blue in response to the oxygen concentration to which the sensor is exposed. The sensor was found to have a linear response to oxygen concentration on a semi-logarithmic scale within the oxygen concentration range between 0.6% and 20.9%, a response time and a recovery time of about 3 s, ant to exhibit good reversibility and repeatability. An increase in temperature from 21.degree. C. to 35.degree. C. does not affect the net absorption of the sensor.

  9. Phanerozoic Atmospheric Oxygen

    NASA Astrophysics Data System (ADS)

    Berner, Robert A.

    Theoretical calculations, based on both the chemical and isotopic composition of sedimentary rocks, indicate that atmospheric O2 has varied appreciably over Phanerozoic time, with a notable excursion during the Permo-Carboniferous reaching levels as high as 35% O2. This agrees with measurements of the carbon isotopic composition of fossil plants together with experiments and calculations on the effect of O2 on photosynthetic carbon isotope fractionation. The principal cause of the excursion was the rise of large vascular land plants and the consequent increased global burial of organic matter. Higher levels of O2 are consistent with the presence of Permo-Carboniferous giant insects, and preliminary experiments indicate that insect body size can increase with elevated O2. Higher O2 also may have caused more extensive, possibly catastrophic, wildfires. To check this, realistic burning experiments are needed to examine the effects of elevated O2 on fire behavior.

  10. Oxygen variability and meridional oxygen supply in the tropical North East Atlantic oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Hahn, Johannes; Brandt, Peter; Greatbatch, Richard J.; Krahmann, Gerd; Körtzinger, Arne

    2013-04-01

    The oxygen minimum zone (OMZ) of the tropical North East Atlantic (TNEA) is located between the oxygen-rich equatorial region and the Cape Verde Frontal Zone at about 20°N in a depth range of 300 - 700 m. Its horizontal extent is predominantly defined by the North Equatorial Current and by the equatorial zonal current system ventilating the region to the north and south of the OMZ, respectively. The interior of the OMZ is characterized by a sluggish flow regime, where mesoscale eddies play a major role in the ventilation. In this study we focus on the oxygen variability in the TNEA as well as the eddy driven lateral ventilation of the TNEA OMZ across its southern boundary. During recent years an intense measurement program was executed along 23°W cutting meridionally through the TNEA OMZ. Hydrographic and velocity data has been acquired from ship sections and moorings, together covering the latitude range between 6°S and 14°N with particularly high meridional resolution of shipboard and high temporal resolution of moored observations. Based on shipboard data we derived a meridional section of oxygen variance, which reveals numerous local maxima of oxygen variability. Exemplary, strong oxygen variability is observed at the upper (300m, 5° - 12°N) and the southern boundary (400m - 700m, 5°N - 8°N) of the OMZ, whereas the interior of the OMZ is characterized by weak variability. An application of the extended Osborn-Cox model shows that the strong oxygen variability at the southern boundary is mainly generated by mesoscale eddies. The strong variability at the upper boundary is generated by mesoscale eddies as well as microscale turbulence. We apply two methods to estimate the meridional oxygen flux: 1) a flux gradient parameterization and 2) a correlation of oxygen and velocity mooring time series. From the analysis of the 5°N mooring data we find a northward oxygen flux directed towards the OMZ at its core depth, that is mainly due to variability of mesoscale eddy motions (10 - 50 days). The magnitude of the oxygen flux is well represented by the flux gradient parameterization, which moreover reveals an overall northward oxygen flux from the southern boundary to the centre of the OMZ. We further estimate the oxygen supply (divergence of oxygen flux) by mesoscale eddies and discuss its contribution to the oxygen budget of the TNEA OMZ.

  11. Mixed oxygen ion/electron-conducting ceramics for oxygen separation

    SciTech Connect

    Stevenson, J.W.; Armstrong, B.L.; Armstrong, T.R.; Bates, J.L.; Pederson, L.R.; Weber, W.J.

    1995-05-01

    Solid mixed-conducting electrolytes in the series La{sub l-x}A{sub x}Co{sub l-y}Fe{sub y}O{sub 3-{delta}} (A = Sr,Ca,Ba) are potentially useful as passive membranes to separate high purity oxygen from air and as cathodes in fuel cells. All of the compositions studied exhibited very high electrical conductivities. At lower temperatures, conductivities increased with increasing temperature, characterized by activation energies of 0.05 to 0.16 eV that are consistent with a small polaron (localized electronic carrier) conduction mechanism. At higher temperatures, electronic conductivities tended to decrease with increasing temperature, which is attributed to decreased electronic carrier populations associated with lattice oxygen loss. Oxygen ion conductivities were higher than that of yttria stabilized zirconia and increased with the cobalt content and also increased with the extent of divalent A-site substitution. Thermogravimetric studies were conducted to establish the extent of oxygen vacancy formation as a function of temperature, oxygen partial pressure, and composition. These vacancy populations strongly depend on the extent of A-site substitution. Passive oxygen permeation rates were established for each of the compositions as a function of temperature and oxygen partial pressure gradient. For 2.5 mm thick membranes in an oxygen vs nitrogen partial pressure gradient, oxygen fluxes at 900 C ranged from approximately 0.3 sccm/cm{sup 2} for compositions high in iron and with low amounts of strontium A-site substitution to approximately 0.8 sccm/cm{sup 2} for compositions high in cobalt and strontium. A-site substitution with calcium instead of strontium resulted in substantially lower fluxes.

  12. The Oxygen a Band

    NASA Astrophysics Data System (ADS)

    Benner, D. Chris; Devi, V. Malathy; Hoo, Jiajun; Hodges, Joseph; Long, David A.; Sung, Keeyoon; Drouin, Brian; Okumura, Mitchio; Bui, Thinh Quoc; Rupasinghe, Priyanka

    2014-06-01

    The oxygen A band is used for numerous atmospheric experiments, but spectral line parameters that sufficiently describe the spectrum to the level required by OCO2 and other high precision/accuracy experiments are lacking. Fourier transform spectra from the Jet Propulsion Laboratory and cavity ring down spectra from the National Institute of Standards and Technology were fitted simultaneously using the William and Mary multispectrum nonlinear least squares fitting technique into a single solution including the entire band. In addition, photoacoustic spectra already available from the California Institute of Technology will be added to the solution. The three types of spectrometers are complementary allowing the strengths of each to fill in the weaknesses of the others. With this technique line positions, intensities, widths, shifts, line mixing, Dicke narrowing, temperature dependences and collision induced absorption have been obtained in a single physically consistent fit. D. Chris Benner, C. P. Rinsland, V. M. Devi, M. A. H. Smith, and D. Atkins, JQSRT 1995;53:705-21. Part of the research described in this paper was performed at The College of William and Mary, the, Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration and the Jet Propulsion Laboratory. Support for the National Institute of Standards and Technology was provided by the NIST Greenhouse Gas Measurements and Climate Research Program and a NIST Innovations in Measurement Science (IMS) award.

  13. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; W.B. Yelon; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and initial studies on newer composition of Ti doped LSF. 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. In addition, studies were also begun to obtain reliable estimates of fracture toughness and stable crack growth in specific environments. Newer composition of Ti doped LSF membranes were characterized by neutron diffraction analysis. Quench studies indicated an apparent correlation between the unit cell volume and oxygen occupancy. The studies however, indicated an anomaly of increasing Fe/Ti ratio with change in heat treatment. Ti doped LSF was also characterized for stoichiometry as a function of temp and pO{sub 2}. The non stoichiometry parameter {delta} was observed to increase almost linearly on lowering pO{sub 2} until a ideal stoichiometric composition of {delta} = 0.175 was approached.

  14. Oxygen production for the synfuels industry

    Microsoft Academic Search

    Drnevich

    1982-01-01

    The expected moderate growth of the synfuels industry will increase the uses of oxygen. Plants to produce SNG will require oxygen. Oxygen will be used to produce hydrogen from coke and heavy byproducts. The oxygen requirements of coal gasification, coal liquefaction, and heavy oil production are specified. An oxygen supply system has three basic components: air compression, cryogenic air separator

  15. Low Oxygen Environments in Chesapeake Bay

    E-print Network

    Boynton, Walter R.

    Low Oxygen Environments in Chesapeake Bay Jeremy Testa Chesapeake Biological Laboratory University of Maryland Center for Environmental Science Why we care about low oxygen? What causes low oxygen? Where and When does Chesapeake Bay lose oxygen? #12;#12;Hypoxia and Chesapeake Animals Low dissolved oxygen

  16. Site determination of oxygen in B6O by oxygen K? x-ray-emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Kawai, J.; Maeda, K.; Higashi, I.; Takami, M.; Hayasi, Y.; Uda, M.

    1990-09-01

    An electron-excited x-ray-emission spectrum of oxygen K? is presented for boron suboxide B6O (isostructural with B13C2). The spectrum is compared with those calculated by the discrete-variation X? (DV-X?) method with various O-O distances as an adjustable parameter in the fixed icosahedral B12 framework. The observed spectrum is reproduced well when the O-O distance is in the range 2.5-3.5 Å. This O-O bond length is more than twice as long as that of a free O2 molecule. The oxygen atom is located very close to the center of the boron triangle (closed three-center bond). These results support the structure determined by x-ray structural analysis.

  17. Measurement of intracellular oxygen concentration during photodynamic therapy in vitro.

    PubMed

    Weston, Mark A; Patterson, Michael S

    2014-01-01

    A technique is introduced that monitors the depletion of intracellular ground state oxygen concentration ([(3)O(2)]) during photodynamic therapy of Mat-LyLu cell monolayers and cell suspensions. The photosensitizer Pd(II) meso-tetra(4-carboxyphenyl)porphine (PdT790) is used to manipulate and indicate intracellular [(3)O(2)] in both of the in vitro models. The Stern-Volmer relationship for PdT790 phosphorescence was characterized in suspensions by flowing nitrogen over the suspension while short pulses of 405 nm light were used to excite the sensitizer. The bleaching of sensitizer and the oxygen consumption rate were also measured during continuous exposure of the cell suspension to the 405 nm laser. Photodynamic therapy (PDT) was conducted in both cell suspensions and in cell monolayers under different treatment conditions while the phosphorescence signal was acquired. The intracellular [(3)O(2)] during PDT was calculated by using the measured Stern-Volmer relationship and correcting for sensitizer photobleaching. In addition, the amount of oxygen that was consumed during the treatments was calculated. It was found that even at large oxygen consumption rates, cells remain well oxygenated during PDT of cell suspensions. For monolayer treatments, it was found that intracellular [(3)O(2)] is rapidly depleted over the course of PDT. PMID:24521344

  18. Quantum design and synthesis of a boron-oxygen-yttrium phase

    Microsoft Academic Search

    Valeriu Chirita; Ulrich Kreissig; Zsolt Czigány; Jochen M. Schneider; Ulf Helmersson

    2003-01-01

    Ab initio calculations are used to design a crystalline boron-oxygen-yttrium (BOY) phase. The essential constituent is yttrium substituting for oxygen in the boron suboxide structure (BO0.17) with Y\\/B and O\\/B ratios of 0.07. The calculations predict that the BOY phase is 0.36 eV\\/atom more stable than crystalline BO0.17 and experiments confirm the formation of crystalline thin films. The BOY phase

  19. 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)

  20. Superposition of Waves Calculator

    NSDL National Science Digital Library

    David Joiner

    The Superposition of Waves Calculators show the result of adding two or more waves of the form y = A * cos ( k * x + phi ) or y = A * cos ( k * x + phi - omega * t ). The calculation of wave packets is also included.

  1. Calculate Your Radiation Dose

    MedlinePLUS

    ... Ionizing & Non-Ionizing Radiation Understanding Radiation: Calculate Your Radiation Dose Health Effects Main Page Exposure Pathways Calculate ... of the US do you live in? Internal radiation (in your body): From food and water, (e. ...

  2. Oxygen Compatibility Screening Tests in Oxygen-Rich Combustion Environment

    NASA Technical Reports Server (NTRS)

    Eckel, Anerew J.

    1997-01-01

    The identification and characterization of oxygen-rich compatible materials enables full-flow, staged combustion designs. Although these oxygen-rich designs offer significant cost, performance, and reliability benefits over existing systems, they have never been used operationally by the United States. If these systems are to be realized, it is critical to understand the long-term oxidative stability in high-temperature, high-pressure, oxygen-rich combustion environments. A unique facility has been constructed at the NASA Lewis Research Center to conduct tests of small-scale rocket engine materials and subcomponents in an oxygen-rich combustion environment that closely approximates a full-scale rocket engine. Thus, a broad range of advanced materials and concepts can be screened in a timely manner and at a relatively low cost.

  3. Vertical distribution of triple oxygen isotopic composition of dissolved oxygen in the northwestern Pacific

    NASA Astrophysics Data System (ADS)

    Abe, Osamu; Honda, Makio; Saino, Toshiro

    2013-04-01

    Oxygen-17 excess of dissolved oxygen calculated from ?18O and ?17O is not affected by oxygen consumption process but controlled only by processes of primary production and air-water gas transfer. Evaluating gross primary productivity using the 17O-excess in ocean surface water are one of the most advanced geochemical researches for last 10 years. Oxygen-17 excess below ocean mixed/photic layer has not been much investigated because it might be out of focus for estimating present primary productivity, except for the purpose to correct diapycnal mixing effect on surface water. In principle, water mass which has not been affected both by photosynthesis and gas transfer after its separation from ocean surface could preserve 17O-excess value where the water mass was at the surface. The purpose of this study is to determine the vertical distribution of 17O-excess from the surface to the bottom of northwestern Pacific to know whether 17O-excess could really preserve its "original" value after the long and dark travel. Near stations K2 and KNOT, water mass which has a density of 26.8 ?? is observed at depth between 100 and 300 m. This water mass is mainly originated from bottom water in the Okhotsk Sea and spreading widely to entire northwestern Pacific, which is called North Pacific Intermediate Water (NPIW). NPIW is found at depth of 700 m at station S1. Samplings were conducted by two R/V Mirai cruises (MR10-06, Oct-Nov 2010; MR11-02, Feb-Mar 2011). Dissolved oxygen gas was purified by the method of Sarma et al. (2003) and its isotopic composition was determined by dual-inlet isotope ratio mass spectrometer (Thermo Scientific Delta Plus). Gross primary productivities at mixed layer estimated by 17O-excess were well consistent with those by conventional light and dark bottle incubations for stations K2 and S1.

  4. Oxygen Transport Ceramic Membranes

    SciTech Connect

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

    2005-11-01

    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 current research, the electrical conductivity and Seebeck coefficient were measured as a function of temperature in air. Based on these measurements, the charge carrier concentration, net acceptor dopant concentration, activation energy of conduction and mobility were estimated. The studies on the fracture toughness of the LSFT and dual phase membranes at room temperature have been completed and reported previously. The membranes that are exposed to high temperatures at an inert and a reactive atmosphere undergo many structural and chemical changes which affects the mechanical properties. To study the effect of temperature on the membranes when exposed to an inert environment, the membranes (LAFT and Dual phase) were heat treated at 1000 C in air and N{sub 2} atmosphere and hardness and fracture toughness of the membranes were studied after the treatment. The indentation method was used to find the fracture toughness and the effect of the heat treatment on the mechanical properties of the membranes. Further results on the investigation of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appears 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. 2-D modeling of oxygen movement has been undertaken in order to fit isotope data. The model will serve to study ''frozen'' profiles in patterned or composite membranes.

  5. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana

    2003-08-07

    In the present quarter, experiments are presented on ceramic/metal interactions of Zirconia/ Ni-B-Si system and with a thin Ti coating deposited on zirconia surface. Existing facilities were modified for evaluation of environmental assisted slow crack growth and creep in flexural mode. Processing of perovskites of LSC, LSF and LSCF composition were continued for evaluation of mechanical properties as a function of environment. These studies in parallel to those on the LSFCO composition is expect to yield important information on questions such as the role of cation segregation and the stability of the perovskite structure on crack initiation vs. crack growth. Studies have been continued on the La{sub 1-x}Sr{sub x}FeO{sub 3-d} composition using neutron diffraction and TGA studies. A transition from p-type to n-type of conductor was observed at relative low pO{sub 2}, at which the majority carriers changed from the holes to electrons because of the valence state decreases in Fe due to the further loss of oxygen. Investigation on the thermodynamic properties of the membrane materials are continued to develop a complete model for the membrane transport. Data obtained at 850 C show that the stoichiometry in La{sub 0.2}Sr{sub 0.8}Fe{sub 0.8}Cr{sub 0.2}O{sub 3-x} vary from {approx}2.85 to 2.6 over the pressure range studied. From the stoichiometry a lower limit of 2.6 corresponding to the reduction of all Fe{sup 4+} to Fe{sup 3+} and no reduction of Cr{sup 3+} is expected.

  6. Oxygenates vs. synthesis gas

    SciTech Connect

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

    1999-04-01

    Methanol synthesis from H{sub 2}/CO has been carried out at 7.6 MPa over zirconia-supported copper catalysts. Catalysts with nominal compositions of 10/90 mol% and 30/70 mol% Cu/ZrO{sub 2} were used in this study. Additionally, a 3 mol% cesium-doped 10/90 catalyst was prepared to study the effect of doping with heavy alkali, and this promoter greatly increased the methanol productivity. The effects of CO{sub 2} addition, water injection, reaction temperature, and H{sub 2}/C0 ratio have been investigated. Both CO{sub 2} addition to the synthesis gas and cesium doping of the catalyst promoted methanol synthesis, while inhibiting the synthesis of dimethyl ether. Injection of water, however, was found to slightly suppress methanol and dimethyl ether formation while being converted to CO{sub 2} via the water gas shift reaction over these catalysts. There was no clear correlation between copper surface area and catalyst activity. Surface analysis of the tested samples revealed that copper tended to migrate and enrich the catalyst surface. The concept of employing a double-bed reactor with a pronounced temperature gradient to enhance higher alcohol synthesis was explored, and it was found that utilization of a Cs-promoted Cu/ZnO/Cr{sub 2}O{sub 3} catalyst as a first lower temperature bed and a Cs-promoted ZnO/Cr{sub 2}O{sub 3} catalyst as a second high-temperature bed significantly promoted the productivity of 2-methyl-1-propanol (isobutanol) from H{sub 2}/CO synthesis gas mixtures. While the conversion of CO to C{sub 2+} oxygenates over the double-bed configuration was comparable to that observed over the single Cu-based catalyst, major changes in the product distribution occurred by the coupling to the zinc chromite catalyst; that is, the productivity of the C{sub 1}-C{sub 3} alcohols decreased dramatically, and 2-methyl branched alcohols were selectively formed. The desirable methanol/2-methyl oxygenate molar ratios close to 1 were obtained in the present double-bed system that provides the feedstock for the synthesis of high octane and high cetane ethers, where the isobutanol productivity was as high as 139 g/kg cat/hr. Higher alcohol synthesis has been investigated over a Cs/Cu/ZnO/Cr{sub 2}O{sub 3} catalyst at temperatures higher (up to 703K) than those previously utilized, and no sintering of the catalyst was observed during the short-term testing. However, the higher reaction temperatures led to lower CO conversion levels and lower yield of alcohols, especially of methanol, because of equilibrium limitations. With the double catalyst bed configuration, the effect of pressure in the range of 7.6--12.4 MPa on catalyst activity and selectivity was studied. The upper bed was composed of the copper-based catalyst at 598K, and the lower bed consisted of a copper-free Cs-ZnO/Cr{sub 2}O{sub 3} catalyst at a high temperature of 678K. High pressure was found to increase CO conversion to oxygenated products, although the increase in isobutanol productivity did not keep pace with that of methanol. It was also shown that the Cs/Cu/ZnO/Cr{sub 2}O{sub 3} catalyst could be utilized to advantage as the second-bed catalyst at 613--643K instead of the previously used copper-free Cs-ZnO/ Cr{sub 2}O{sub 3} catalyst at higher temperature, With double Cs/Cu/ZnO/Cr{sub 2}O{sub 3} catalysts, high space time yields of up to 202 g/kg cat/hr, with high selectivity to isobutanol, were achieved.

  7. STL Oxygen Generator System (OGS)

    NSDL National Science Digital Library

    1999-01-01

    Scientist K.R. Sridhar and a twenty-member research team at the University of Arizona Aerospace and Mechanical Engineering (AME) Department are building an Oxygen Generating Subsystem (OGS). This unit is set to be launched into Martian atmosphere in January 2002. When the system is on Mars, it will "suck in Martian atmospheric gases--predominantly carbon dioxide--and process them to produce pure oxygen." The website is of the Oxygen Generator System at the University of Arizona. This site provides more information about the system as well as the team of scientists.

  8. Scalable chemical oxygen - iodine laser

    SciTech Connect

    Adamenkov, A A; Bakshin, V V; Vyskubenko, B A; Efremov, V I; Il'in, S P; Ilyushin, Yurii N; Kolobyanin, Yu V; Kudryashov, E A; Troshkin, M V [Russian Federal Nuclear Center 'All-Russian Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod region (Russian Federation)

    2011-12-31

    The problem of scaling chemical oxygen - iodine lasers (COILs) is discussed. The results of experimental study of a twisted-aerosol singlet oxygen generator meeting the COIL scalability requirements are presented. The energy characteristics of a supersonic COIL with singlet oxygen and iodine mixing in parallel flows are also experimentally studied. The output power of {approx}7.5 kW, corresponding to a specific power of 230 W cm{sup -2}, is achieved. The maximum chemical efficiency of the COIL is {approx}30%.

  9. Hyperbaric oxygen therapy in China.

    PubMed

    Yan, Ling; Liang, Ting; Cheng, Oumei

    2015-01-01

    Hyperbaric oxygen therapy (HBOT) is defined as a treatment in which a patient intermittently breathes 100% oxygen while the treatment chamber is pressurized to a pressure greater than sea level (1.0 atmosphere absolute, ATA). In China, for nearly 50 years, HBOT has been used as a primary or adjuvant therapy to treat a variety of diseases. This article mainly reviewed the indications and contraindications of HBOT, as well as the status of clinical and experimental HBOT research in China. At the same time, there is a brief introduction of hyperbaric oxygen preconditioning (HBO-PC) in China. PMID:25722849

  10. Oxygen in dense interstellar gas. The oxygen abundance of the star forming core ? Ophiuchi A

    NASA Astrophysics Data System (ADS)

    Liseau, R.; Justtanont, K.

    2009-06-01

    Context: Oxygen is the third most abundant element in the universe, but its chemistry in the interstellar medium is still not understood well. Aims: To critically examine the entire oxygen budget, we initially attempt to estimate the abundance of atomic oxygen, O, in the only region where molecular oxygen, O{2}, has been detected to date. Methods: We analysed ISOCAM-CVF spectral image data toward ? Oph A to derive the temperatures and column densities of H{2} at the locations of ISO-LWS observations of two [O I] ^3P{J} lines. The intensity ratios of the (J = 1-2) 63 ?m to (J = 0-1) 145 ?m lines largely exceed ten, attesting to these lines being optically thin. This is confirmed by radiative transfer calculations, making these lines suitable for abundance determinations. For that purpose, we calculated line strengths and compared them to the LWS observations. Results: Excess [O I] emission is observed to be associated with the molecular outflow from VLA 1623. For this region, we determine the physical parameters, T and N(H{2}), from the CAM observations, and the gas density, n(H{2}), is determined from the flux ratio of the [O i] 63 ?m and [O i] 145 ?m lines. For the oxygen abundance, our analysis essentially leads to three possibilities: (1) extended low-density gas with standard ISM O-abundance, (2) compact high-density gas with standard ISM O-abundance, and (3) extended high-density gas with reduced oxygen abundance, [O/H] 2 × 10-5. Conclusions: As option (1) disregards valid [O i] 145 ?m data, we do not find it very compelling; instead, we favour option (3), as lower abundances are expected as a result of chemical cloud evolution, but we are not able to dismiss option (2) entirely. Observations at higher angular resolution than offered by the LWS are required to decide between these possibilities. Based on observations with the CAM-CVF (Cesarsky et al. 1996) and the LWS (Clegg et al. 1996) onboard the Infrared Space Observatory, ISO (Kessler et al. 1996).

  11. Computer-assisted numerical analysis for oxygen and carbon dioxide mass transfer in blood oxygenators.

    PubMed

    Turri, Fabio; Yanagihara, Jurandir Itizo

    2011-06-01

    A two-dimensional numeric simulator is developed to predict the nonlinear, convective-reactive, oxygen mass exchange in a cross-flow hollow fiber blood oxygenator. The numeric simulator also calculates the carbon dioxide mass exchange, as hemoglobin affinity to oxygen is affected by the local pH value, which depends mostly on the local carbon dioxide content in blood. Blood pH calculation inside the oxygenator is made by the simultaneous solution of an equation that takes into account the blood buffering capacity and the classical Henderson-Hasselbach equation. The modeling of the mass transfer conductance in the blood comprises a global factor, which is a function of the Reynolds number, and a local factor, which takes into account the amount of oxygen reacted to hemoglobin. The simulator is calibrated against experimental data for an in-line fiber bundle. The results are: (i) the calibration process allows the precise determination of the mass transfer conductance for both oxygen and carbon dioxide; (ii) very alkaline pH values occur in the blood path at the gas inlet side of the fiber bundle; (iii) the parametric analysis of the effect of the blood base excess (BE) shows that (.)V(CO?) is similar in the case of blood metabolic alkalosis, metabolic acidosis, or normal BE, for a similar blood inlet P(CO?), although the condition of metabolic alkalosis is the worst case, as the pH in the vicinity of the gas inlet is the most alkaline; (iv) the parametric analysis of the effect of the gas flow to blood flow ratio (QG/QB) shows that (.)V(CO?) variation with the gas flow is almost linear up to QG/QB = 2.0. (.)V(O?) is not affected by the gas flow as it was observed that by increasing the gas flow up to eight times, the (.)V(O?) grows only 1%. The mass exchange of carbon dioxide uses the full length of the hollow-fiber only if Q(G) /Q(B)> 2.0, as it was observed that only in this condition does the local variation of pH and blood P(CO?) comprise the whole fiber bundle. PMID:21671959

  12. Ecological Footprint Calculators

    NSDL National Science Digital Library

    EcoBusinessLinks

    This website contains interactive calculators for determining various environmental impacts. The site includes more than 15 different calculators to determine greenhouse gas emissions, ecological footprints, electricity pollution, air travel pollution, commuting costs, appliance costs, pollution prevention and more. These calculators can be used for computer-based classroom activities or to enable students to see which types of activities have the greatest environmental impact.

  13. Multiphase flow calculation software

    Microsoft Academic Search

    Fincke; James R

    2003-01-01

    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,

  14. Calculating a Mineral's Density

    NSDL National Science Digital Library

    Andrea Distelhurst

    2011-10-05

    Students will use the Density=Mass/Volume formula to calculate the density of an unknown mineral. By using water displacement and a triple beam balance students will collect measurements of volume and mass for an unknown mineral. With this data, they will calculate the mineral's density then identify the mineral based on calculated density.

  15. Geochemical Calculations Using Spreadsheets.

    ERIC Educational Resources Information Center

    Dutch, Steven Ian

    1991-01-01

    Spreadsheets are well suited to many geochemical calculations, especially those that are highly repetitive. Some of the kinds of problems that can be conveniently solved with spreadsheets include elemental abundance calculations, equilibrium abundances in nuclear decay chains, and isochron calculations. (Author/PR)

  16. Calculator-Active Materials.

    ERIC Educational Resources Information Center

    Crow, Tracy, Ed.; Harris, Julia, Ed.

    1997-01-01

    This journal contains brief descriptions of calculator-active materials that were found using Resource Finder, the searchable online catalog of curriculum resources from the Eisenhower National Clearinghouse (ENC). It features both the calculators themselves and the activity books that are used with them. Among the calculators included are those…

  17. What Are the Risks of Oxygen Therapy?

    MedlinePLUS

    ... from the NHLBI on Twitter. What Are the Risks of Oxygen Therapy? Oxygen therapy can cause complications ... supplies may reduce the risk of complications. Other Risks In certain people, oxygen therapy may suppress the ...

  18. 46 CFR 154.1360 - Oxygen analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Oxygen analyzer. 154.1360 Section 154...Equipment Instrumentation § 154.1360 Oxygen analyzer. The vessel must have a portable analyzer that measures oxygen levels in an inert...

  19. 46 CFR 154.1360 - Oxygen analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Oxygen analyzer. 154.1360 Section 154...Equipment Instrumentation § 154.1360 Oxygen analyzer. The vessel must have a portable analyzer that measures oxygen levels in an inert...

  20. 46 CFR 154.1360 - Oxygen analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Oxygen analyzer. 154.1360 Section 154...Equipment Instrumentation § 154.1360 Oxygen analyzer. The vessel must have a portable analyzer that measures oxygen levels in an inert...

  1. 76 FR 12550 - Lavatory Oxygen Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-08

    ...SFAR 111] RIN 2120-AJ92 Lavatory Oxygen Systems AGENCY: Federal Aviation Administration...related to the provisioning of supplemental oxygen inside lavatories. This action is necessitated...mandatory actions that temporarily render such oxygen systems inoperative. DATES: This...

  2. 78 FR 5707 - Lavatory Oxygen Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-28

    ...121-362] RIN 2120-AK14 Lavatory Oxygen Systems AGENCY: Federal Aviation Administration...related to the provisioning of supplemental oxygen inside lavatories. This action is necessitated...mandates actions that restore supplemental oxygen to lavatories. DATES: This final...

  3. 46 CFR 154.1360 - Oxygen analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Oxygen analyzer. 154.1360 Section 154...Equipment Instrumentation § 154.1360 Oxygen analyzer. The vessel must have a portable analyzer that measures oxygen levels in an inert...

  4. Biogeochemical Modeling of the Second Rise of Oxygen

    NASA Astrophysics Data System (ADS)

    Smith, M. L.; Catling, D.; Claire, M.; Zahnle, K.

    2014-03-01

    The rise of atmospheric oxygen set the tempo for the evolution of complex life on Earth. Oxygen levels are thought to have increased in two broad steps: one step occurred in the Archean ~ 2.45 Ga (the Great Oxidation Event or GOE), and another step occured in the Neoproterozoic ~750-580 Ma (the Neoprotoerozoic Oxygenation Event or NOE). During the NOE, oxygen levels increased from ~1-10% of the present atmospheric level (PAL) (Holland, 2006), to ~15% PAL in the late Neoproterozoic, to ~100% PAL later in the Phanerozoic. Complex life requires O2, so this transition allowed complex life to evolve. We seek to understand what caused the NOE. To explore causes for the NOE, we build upon the biogeochemical model of Claire et al. (2006), which calculates the redox evolution of the atmosphere, ocean, biosphere, and crust in the Archean through to the early Proterozoic. In this model, the balance between oxygenconsuming and oyxgen-producing fluxes evolves over time such that at ~2.4 Ga, the rapidly acting sources of oxygen outweigh the rapidly-acting sinks. Or, in other words, at ~2.4 Ga, the flux of oxygen from organic carbon burial exceeds the sinks of oxygen from reaction with reduced volcanic and metamoprphic gases. The model is able to drive oxygen levels to 1-10% PAL in the Proterozoic; however, the evolving redox fluxes in the model cannot explain how oxygen levels pushed above 1-10% in the late Proterozoic. The authors suggest that perhaps another buffer, such as sulfur, is needed to describe Proterozoic and Phanerozoic redox evolution. Geologic proxies show that in the Proterozoic, up to 10% of the deep ocean may have been sulfidic. With this ocean chemistry, the global sulfur cycle would have worked differently than it does today. Because the sulfur and oxygen cycles interact, the oxygen concentration could have permanently changed due to an evolving sulfur cycle (in combination with evolving redox fluxes associated with other parts of the oxygen cycle and carbon cycles). To determine how fluxes of sulfur, carbon, and oxygen define oxygen levels before, during, and after the NOE, we add a sulfur cycle to the biogeochemical model of Claire et al. (2006). Understanding processes that impact the evolution of atmospheric oxygen on Earth is key to diagnosing the habitability of other planets because it is possible that other planets undergo a similar evolution. If a sulfidic deep ocean was instrumental in driving oxygen levels to modern values, then it would be valuable to remotely detect a sulfide-rich ocean on another planet. One such remotely-detectable signature could be the color of a sulfide-rich ocean. For example, Gallardo and Espinoza (2008) have hypothesized that a sulfidic ocean may be have been blacker in color. Even if a sulfidic ocean is not key to oxygenation, detecting a planet in transition--that is, a planet with intermediate levels of oxygen co-existing with higher levels of reduced gases - would be important for diagnosing habitability.

  5. Characteristics of high-temperature solid-electrolyte oxygen pumps specific electrical energy consumption

    SciTech Connect

    Voloshchenko, G.N.; Korovin, N.V.; Slavnov, Yu.A.

    1988-03-01

    In order to select the optimal operating conditions for oxygen pumps with low energy consumption it is necessary to calculate the relation between the specific electrical energy requirements for the production of pure oxygen and the working parameters of the oxygen pump. A schematic illustrates an electrochemical cell with ceramic solid electrolyte and the porous electrodes applied to the electrolyte from both sides. The amount of pure oxygen obtained was determined algebraically according to Faraday's law. The way of combining the electrochemical cells was found to have no effect on the specific energy requirements and these requirements can be determined numerical expressions.

  6. Systemic oxygen extraction during exercise at high altitude

    PubMed Central

    Martin, D. S.; Cobb, A.; Meale, P.; Mitchell, K.; Edsell, M.; Mythen, M. G.; Grocott, M. P. W.; Adams, Tom; Biseker, Lindsay; Booth, Adam; Burdall, Oliver; Cobb, Alexandra; Cumpstey, Andrew; Dauncey, Steve; Edsell, Mark; Farrant, James; Feelisch, Martin; Fernandez, Bernadette; Firth, Oliver; Gilbert, Edward; Grant, Daniel; Grocott, Michael; Hennis, Phil; Jackson, Laura; Jenner, Will; van der Kaaij, Jildou; Khosravi, Maryam; Kortekaas, Edith; Levett, Denny; Mahomed, Zeyn; Martin, Daniel; Meale, Paula; Milledge, Jim; Mitchell, Kay; Mole, Damian; Moses, Oliver; Mythen, Michael; Rigat, Fabio; O'Doherty, Alasdair; Salam, Alex; Sanborn, Matt; Sheperdigian, Adam; Shrubb, Fiona; Simpson, Jo; Talbot, Nick; Wandrag, Liesel; Wijesingha, Savini; Williamson, Wilby; Woolley, Tom; Yow, Heng

    2015-01-01

    Background Classic teaching suggests that diminished availability of oxygen leads to increased tissue oxygen extraction yet evidence to support this notion in the context of hypoxaemia, as opposed to anaemia or cardiac failure, is limited. Methods At 75 m above sea level, and after 7–8 days of acclimatization to 4559 m, systemic oxygen extraction [C(a?v)O2] was calculated in five participants at rest and at peak exercise. Absolute [C(a?v)O2] was calculated by subtracting central venous oxygen content (CcvO2) from arterial oxygen content (CaO2) in blood sampled from central venous and peripheral arterial catheters, respectively. Oxygen uptake (V?O2) was determined from expired gas analysis during exercise. Results Ascent to altitude resulted in significant hypoxaemia; median (range) SpO2 87.1 (82.5–90.7)% and PaO2 6.6 (5.7–6.8) kPa. While absolute C(a?v)O2 was reduced at maximum exercise at 4559 m [83.9 (67.5–120.9) ml litre?1 vs 99.6 (88.0–151.3) ml litre?1 at 75 m, P=0.043], there was no change in oxygen extraction ratio (OER) [C(a?v)O2/CaO2] between the two altitudes [0.52 (0.48–0.71) at 4559 m and 0.53 (0.49–0.73) at 75 m, P=0.500]. Comparison of C(a?v)O2 at peak V?O2 at 4559 m and the equivalent V?O2 at sea level for each participant also revealed no significant difference [83.9 (67.5–120.9) ml litre1 vs 81.2 (73.0–120.7) ml litre?1, respectively, P=0.225]. Conclusion In acclimatized individuals at 4559 m, there was a decline in maximum absolute C(a?v)O2 during exercise but no alteration in OER calculated using central venous oxygen measurements. This suggests that oxygen extraction may have become limited after exposure to 7–8 days of hypoxaemia. PMID:25501722

  7. Productivity and heat generation of fermentation under oxygen limitation

    Microsoft Academic Search

    I. G. Minkevich; V. K. Eroshin

    1973-01-01

    The elemental balance equation of microbial growth on carbon substrate of generalized composition is given. Yield of dried\\u000a bio-mass per oxygenY\\u000a o is calculated. Yield per oxygenY\\u000a o is found to be determined by two factors—carbon yieldy and the reducing power of substrate ?\\u000a s\\u000a . The mode of dependence ofY\\u000a o on these two quantities is studied. The energetic

  8. Effective Potential Energies and Transport Properties for Nitrogen and Oxygen

    NASA Technical Reports Server (NTRS)

    Stallcop, James R.; Partridge, Harry; Levin, Eugene; Kwak, Dochan (Technical Monitor)

    2001-01-01

    The results of recent theoretical studies for N--N2, O--O2, N2--N2 interactions are applied to the transport properties of nitrogen and oxygen gases. The theoretical results are used to select suitable oxygen interaction energies from previous work for determining the diffusion and viscosity coefficients at high temperatures. A universal formulation is applied to determine the collision integrals for O2--O2 interactions at high temperatures and to calculate certain ratios for determining higher-order collision integrals.

  9. The measurement of hemoglobin oxygen saturation using multiwavelength photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Deng, Zilin; Yang, Xiaoquan; Yu, Lejun; Gong, Hui

    2009-10-01

    Hemoglobin oxygen saturation (SO2) is one of the most critical functional parameters to the metabolism. In this paper, we mainly introduced some initial results of measuring blood oxygen using multi-wavelength photoacoustic microscopy (PAM). In phantom study, we demonstrate the photoacoustic signal amplitude increases linearly with the concentration of red or blue ink. Then the calculated concentration of red ink in double-ink mixtures with PAM has a 5% difference with the result measured with spectrophotometric analysis. In ex vivo experiment, the measured result exhibt 15% difference between the PAM and spectrophotometric analysis. Experiment results suggest that PAM could be used to determine the SO2 quantitatively.

  10. The measurement of hemoglobin oxygen saturation using multiwavelength photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Deng, Zilin; Yang, Xiaoquan; Yu, Lejun; Gong, Hui

    2010-02-01

    Hemoglobin oxygen saturation (SO2) is one of the most critical functional parameters to the metabolism. In this paper, we mainly introduced some initial results of measuring blood oxygen using multi-wavelength photoacoustic microscopy (PAM). In phantom study, we demonstrate the photoacoustic signal amplitude increases linearly with the concentration of red or blue ink. Then the calculated concentration of red ink in double-ink mixtures with PAM has a 5% difference with the result measured with spectrophotometric analysis. In ex vivo experiment, the measured result exhibt 15% difference between the PAM and spectrophotometric analysis. Experiment results suggest that PAM could be used to determine the SO2 quantitatively.

  11. Quantification of global myocardial oxygenation in humans: initial experience

    PubMed Central

    2010-01-01

    Purpose To assess the feasibility of our newly developed cardiovascular magnetic resonance (CMR) methods to quantify global and/or regional myocardial oxygen consumption rate (MVO2) at rest and during pharmacologically-induced vasodilation in normal volunteers. Methods A breath-hold T2 quantification method is developed to calculate oxygen extraction fraction (OEF) and MVO2 rate at rest and/or during hyperemia, using a two-compartment model. A previously reported T2 quantification method using turbo-spin-echo sequence was also applied for comparison. CMR scans were performed in 6 normal volunteers. Each imaging session consisted of imaging at rest and during adenosine-induced vasodilation. The new T2 quantification method was applied to calculate T2 in the coronary sinus (CS), as well as in myocardial tissue. Resting CS OEF, representing resting global myocardial OEF, and myocardial OEF during adenosine vasodilation were then calculated by the model. Myocardial blood flow (MBF) was also obtained to calculate MVO2, by using a first-pass perfusion imaging approach. Results The T2 quantification method yielded a hyperemic OEF of 0.37 ± 0.05 and a hyperemic MVO2 of 9.2 ± 2.4 ?mol/g/min. The corresponding resting values were 0.73 ± 0.05 and 5.2 ± 1.7 ?mol/g/min respectively, which agreed well with published literature values. The MVO2 rose proportionally with rate-pressure product from the rest condition. The T2 sensitivity is approximately 95% higher with the new T2 method than turbo-spin-echo method. Conclusion The CMR oxygenation method demonstrates the potential for non-invasive estimation of myocardial oxygenation, and should be explored in patients with altered myocardial oxygenation. PMID:20525217

  12. Numerical modeling of anisotropic fiber bundle behavior in oxygenators.

    PubMed

    Bhavsar, Sonya S; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2011-11-01

    Prediction of flow patterns through oxygenator fiber bundles can allow shape optimization so that efficient gas exchange occurs with minimal thrombus formation and hemolysis. Computational fluid dynamics (CFD) simulations can be used to predict three-dimensional flow velocities and flow distribution from spatially dependent variables and they allow estimations of erythrocyte residence time within the fiber bundle. This study builds upon previous work to develop an accurate numerical model for oxygenators, which would allow for accelerated iterations in oxygenator shape and diffuser plate design optimization. Hollow fiber flow channels were developed to permit experimental calculation of fluid permeability in two directions: main flow along the hollow fiber and perpendicular to the hollow fibers. Commercial software was used to develop three-dimensional CFD models of the experimental flow channels and an anisotropic porous media model for oxygenators from these experimental results. The oxygenator model was used to predict pressure loss throughout the device, visualize blood distribution within the fiber bundle, and estimate erythrocyte residence time within the bundle. Experimental flow channels measurements produced a streamwise permeability of 1.143e(-8) m(2) and transverse permeability of 2.385e(-9) m(2) . These permeabilities, coupled with previous work with volume porosity, were used to develop the numerical model of anisotropic behavior through porous fiber bundles, which indicated a more uniform flow field throughout the oxygenator. Incorporation of known anisotropic fiber bundle behavior in previous numerical models more accurately represents fluid behavior through an oxygenator fiber bundle. CFD coupled with experimental validation can produce a powerful tool for oxygenator design and development. PMID:21973082

  13. HETEROGENOUS DEGRADATION OF OXYGENATED INTERMEDIATES

    EPA Science Inventory

    Issues surrounding the importance of including heterogeneous processes when determining the fate of oxygenated intermediates in the troposphere are discussed. esults of recent investigations are reviewed and preliminary data from a laboratory study are presented. n the laboratory...

  14. Solid State oxygen Sensor Development

    NASA Technical Reports Server (NTRS)

    Cheung, Jeffery T.; Johnson, Scott R.

    1994-01-01

    To anticipate future long-duration mission needs for life support sensors, we explored the feasibility of using thin-film metal-oxide semiconductors. The objective of this task was to develop gas sensors for life support applications which would be suitable for long-duration missions. Metal oxides, such as ZnO, SnO2, and TiO2 have been shown to react with oxygen molecules. Oxygen lowers the metal oxide's electrical resistance. Critical to the performance is the application of the oxide in a thin film on an inert substrate: the thinner the film, the more readily the oxygen penetration and hence the more rapid and sensitive the sensor. Metal oxides are not limited to oxygen detection, rather, oxides offer detection and quantification applications to the complete range of gases of interest, not only for life support systems, but for propellants as well.

  15. 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…

  16. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana; Thomas W. Eagar; Harold R. Larson; Raymundo Arroyave; X.-D Zhou; Y.-W. Shin; H.U. Anderson; Nigel Browning; Alan Jacobson; C.A. Mims

    2003-11-01

    The present quarterly report describes some of the initial studies on newer compositions and also includes newer approaches to address various materials issues such as in metal-ceramic sealing. The current quarter's research has also focused on developing a comprehensive reliability model for predicting the structural behavior of the membranes in realistic conditions. In parallel to industry provided compositions, models membranes have been evaluated in varying environment. Of importance is the behavior of flaws and generation of new flaws aiding in fracture. Fracture mechanics parameters such as crack tip stresses are generated to characterize the influence of environment. Room temperature slow crack growth studies have also been initiated in industry provided compositions. The electrical conductivity and defect chemistry of an A site deficient compound (La{sub 0.55}Sr{sub 0.35}FeO{sub 3}) was studied. A higher conductivity was observed for La{sub 0.55}Sr{sub 0.35}FeO{sub 3} than that of La{sub 0.60}Sr{sub 0.40}FeO{sub 3} and La{sub 0.80}Sr{sub 0.20}FeO{sub 3}. Defect chemistry analysis showed that it was primarily contributed by a higher carrier concentration in La{sub 0.55}Sr{sub 0.35}FeO{sub 3}. Moreover, the ability for oxygen vacancy generation is much higher in La{sub 0.55}Sr{sub 0.35}FeO{sub 3} as well, which indicates a lower bonding strength between Fe-O and a possible higher catalytic activity for La{sub 0.55}Sr{sub 0.35}FeO{sub 3}. The program continued to investigate the thermodynamic properties (stability and phase separation behavior) and total conductivity of prototype membrane materials. The data are needed together with the kinetic information to develop a complete model for the membrane transport. Previous report listed initial measurements on a sample of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-x} prepared in-house by Praxair. Subsequently, a second sample of powder from a larger batch of sample were characterized and compared with the results from the previous batch.

  17. Oxygen chemisorption on copper (110)

    NASA Astrophysics Data System (ADS)

    Mundenar, J. M.; Baddorf, A. P.; Plummer, E. W.; Sneddon, L. G.; Didio, R. A.; Zehner, D. M.

    1987-09-01

    High resolution electron energy loss spectroscopy (EELS) and angle-resolved ultra-violet photoelectron spectroscopy (UPS) have been used: (1) to study a surface phonon of Cu(110) as a function of oxygen coverage, (2) to identify oxygen adsorption site(s) in the p(2×1)O, c(6×2)O, and disordered oxygen overlayer (formed by O 2 exposure at 100 K), and (3) to determine whether molecular adsorption or dissociation of O 2 followed by atomic adsorption occurs after oxygen exposure at 100 K. With EELS, a continuous shift in energy of the surface phonon as a function of oxygen exposure at 300 K is observed. Our EELS data for the p(2×1)O overlayer support previous reports of a single long-bridge adsorption site, while indicating two sites are populated in the c(6×2)O overlayer: a long-bridge site and a four-coordinated site. The long-bridge site is populated at all coverages while the four-coordinated sites is occupied only after high exposures (?2×10 4 L) at room temperature, or after exposures >2 L at low temperature (100 K). For both conditions the oxygen coverages are greater than 0.5 monolayer. Also, EELS and complementary UPS data clearly show that oxygen adsorbs dissociatively on Cu(110) after O 2 exposure at 100 K. At this temperature, LEED results indicate that the oxygen atoms are adsorbed without long-range order; however, local adsorption sites, which are similar to those in the c(6×2)O surface, are observed.

  18. Oxygen depletion of bismuth molybdates

    Microsoft Academic Search

    L. K. Yong; R. F. Howe; G. W. Keulks; W. K. Hall

    1978-01-01

    Pure ..cap alpha..-phase bismuth molybdate (BiâMoâOââ), which is known to be weakly active for selective oxidation, and pure ..gamma..-phase bismuth molybdate (BiâMoOâ), which has good activity, were subjected to oxidation-reduction cycles with known amounts of hydrogen and oxygen, at 300°⁻⁵⁷°sup 0\\/C and with evacuation steps between treatments. The volume of oxygen consumed during reoxidation was equal to half the hydrogen

  19. Climatic influences on the oxygen isotopic composition of biogenic silica in prairie grass

    NASA Astrophysics Data System (ADS)

    Webb, Elizabeth A.; Longstaffe, Fred J.

    2002-06-01

    Samples of Calamovilfa longifolia were collected from across the North American prairies to investigate the relationship between the oxygen-isotope composition of biogenic silica (phytoliths) deposited in this grass and relative humidity, temperature, and the oxygen-18 enrichment of soil water relative to local precipitation. The ? 18O values of silica in nontranspiring tissues were controlled by soil-water composition and temperature, whereas the oxygen-18 content of silica formed in leaf and inflorescence tissues was enriched further by transpiration. Accurate calculation of growing temperature was possible only when the oxygen-isotope compositions of both stem silica and soil water were known. However, the oxygen-isotope values of stem phytoliths can be used to calculate the variation in the isotopic composition of soil water across a North American temperature gradient. As plant organic matter decays and phytoliths are transferred to the soil, the temperature and soil-water signals carried by the oxygen-isotope composition of silica from nontranspiring tissues can be masked by the oxygen-18 enrichment of phytoliths from transpiring tissues. However, the overall oxygen-isotope composition of a soil-phytolith assemblage can be related to temperature using an empirical relationship based on temperature and the difference between soil-phytolith and estimated soil-water oxygen-isotope compositions.

  20. Oxygen and Early Animal Evolution

    NASA Astrophysics Data System (ADS)

    Xiao, S.

    2012-12-01

    It is often hypothesized that the rise of animals was triggered by an increase in O2 levels in the atmosphere and oceans. However, this hypothesis is remarkably difficult to test, because the timing of animal divergences is poorly resolved, the physiology of early animals is often unknown, estimates of past pO2 levels come with large error bars, and causal relationships between oxygenation and animal evolution are difficult to establish. Nonetheless, existing phylogenetic, paleontological, and geochemical data indicate that the evolution of macroscopic animals and motile macrometazoans with energetically expensive lifestyles may be temporally coupled with ocean oxygenation events in the Ediacaran Period. Thus, it is plausible that ocean oxygenation may have been a limiting factor in the early evolution of macroscopic, complex, and metabolically aggressive animals (particularly bilaterian animals). However, ocean oxygenation and animal evolution were likely engaged in two-way interactions: Ediacaran oxygenation may have initially lifted a physiological barrier for the evolution of animal size, motility, and active lifestyles, but subsequent animal diversification in the Paleozoic may have also changed oceanic redox structures. Viewed in a broader context, the early evolutionary history of animals was contingent upon a series of events, including genetic preparation (developmental genetics), environmental facilitation (oceanic oxygenation), and ecological escalation (Cambrian explosion), but the rise of animals to ecological importance also had important geobiological impacts on oceanic redox structures, sedimentary fabrics, and global geochemical cycles.

  1. Oxygen discharge and post-discharge kinetics experiments and modeling for the electric oxygen-iodine laser system.

    PubMed

    Palla, A D; Zimmerman, J W; Woodard, B S; Carroll, D L; Verdeyen, J T; Lim, T C; Solomon, W C

    2007-07-26

    Laser oscillation at 1315 nm on the I(2P1/2)-->I(2P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1Delta) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels of complexity to the singlet oxygen generator (SOG) kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. The advanced model BLAZE-IV has been introduced to study the energy-transfer laser system dynamics and kinetics. Levels of singlet oxygen, oxygen atoms, and ozone are measured experimentally and compared with calculations. The new BLAZE-IV model is in reasonable agreement with O3, O atom, and gas temperature measurements but is under-predicting the increase in O2(a1Delta) concentration resulting from the presence of NO in the discharge and under-predicting the O2(b1Sigma) concentrations. A key conclusion is that the removal of oxygen atoms by NOX species leads to a significant increase in O2(a1Delta) concentrations downstream of the discharge in part via a recycling process; however, there are still some important processes related to the NOX discharge kinetics that are missing from the present modeling. Further, the removal of oxygen atoms dramatically inhibits the production of ozone in the downstream kinetics. PMID:17461557

  2. Variation of pressure limits of flame propagation with tube diameter for various isooctane-oxygen-nitrogen mixtures

    NASA Technical Reports Server (NTRS)

    Spakowski, Adolph, A; Belles, Frank E

    1952-01-01

    An investigation was made of the change in the pressure limits of flame propagation with tube diameter for various isooctane-oxygen-nitrogen mixtures. Pressure limits were measured in cylindrical glass tubes of four different inside diameters at six different oxygen-nitrogen ratios. Under the experimental conditions, flame propagation was found to be impossible in isooctane-oxygen mixtures with oxygen concentrations less than 11 to 12 percent. Critical tube diameters for flame propagation were calculated and the effect of pressure was determined and compared with the effect of pressure on quenching distance. Critical diameters were related to flame speeds for various isooctane-oxygen-nitrogen mixtures.

  3. In situ global method for measurement of oxygen demand and mass transfer

    SciTech Connect

    Klasson, K.T. [Oak Ridge National Lab., TN (United States). Chemical Technology Div.; Lundbaeck, K.M.O.; Clausen, E.C.; Gaddy, J.L. [Univ. of Arkansas, Fayetteville, AR (United States). Dept. of Chemical Engineering

    1997-05-01

    Two aerobic microorganisms, Saccharomycopsis lipolytica and Brevibacterium lactofermentum, have been used in a study of mass transfer and oxygen uptake from a global perspective using a closed gas system. Oxygen concentrations in the gas and liquid were followed using oxygen electrodes, and the results allowed for easy calculation of in situ oxygen transport. The cell yields on oxygen for S. lipolytica and B. lactofermentum were 1.01 and 1.53 g/g respectively. The mass transfer coefficient was estimated as 10 h{sup {minus}1} at 500 rpm for both fermentations. The advantages with this method are noticeable since the use of model systems may be avoided, and the in situ measurements of oxygen demand assure reliable data for scale-up.

  4. Origin of deep subgap states in amorphous indium gallium zinc oxide: Chemically disordered coordination of oxygen

    SciTech Connect

    Sallis, S.; Williams, D. S. [Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States); Butler, K. T.; Walsh, A. [Center for Sustainable Technologies and Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Quackenbush, N. F. [Department of Physics, Applied Physics, and Astronomy, Binghamton University, Binghamton, New York 13902 (United States); Junda, M.; Podraza, N. J. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States); Fischer, D. A.; Woicik, J. C. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); White, B. E.; Piper, L. F. J., E-mail: lpiper@binghamton.edu [Department of Physics, Applied Physics, and Astronomy, Binghamton University, Binghamton, New York 13902 (United States); Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States)

    2014-06-09

    The origin of the deep subgap states in amorphous indium gallium zinc oxide (a-IGZO), whether intrinsic to the amorphous structure or not, has serious implications for the development of p-type transparent amorphous oxide semiconductors. We report that the deep subgap feature in a-IGZO originates from local variations in the oxygen coordination and not from oxygen vacancies. This is shown by the positive correlation between oxygen composition and subgap intensity as observed with X-ray photoelectron spectroscopy. We also demonstrate that the subgap feature is not intrinsic to the amorphous phase because the deep subgap feature can be removed by low-temperature annealing in a reducing environment. Atomistic calculations of a-IGZO reveal that the subgap state originates from certain oxygen environments associated with the disorder. Specifically, the subgap states originate from oxygen environments with a lower coordination number and/or a larger metal-oxygen separation.

  5. A method for measuring the spatial distribution of tissue oxygen removal rates.

    PubMed

    Constable, T B; Evans, N T

    1975-11-01

    Distributions of oxygen removal rates are measured over cut surfaces of samples of recently excised tissue. The samples are initially equilibrated with a gas of known oxygen tension and the surface is occluded by bringing it into contact with the end of a glass rod which has a number of polarographic electrodes embedded in it. The oxygen removal rate in mm Hg/sec is calculated from the rate of fall of surface oxygen tension. 91 electrodes are arranged in an array with 0.5 mm separation and each gives an estimate of the oxygen removal rate with a spatial resolution of a few hundred microns. An artificial medium of uniform and controllable respiration rate was used to test the system. Spatial variations in oxygen removal rate were demonstrated in some transplantable rodent tumours. PMID:1202598

  6. Predicting oxygen vacancy non-stoichiometric concentration in perovskites from first principles

    NASA Astrophysics Data System (ADS)

    Luo, Heng; Shin, Yongwoo; Yu, Yang; Cetin, Deniz; Ludwig, Karl; Pal, Uday; Basu, Soumendra N.; Gopalan, Srikanth; Lin, Xi

    2014-12-01

    Formation of oxygen vacancies by introducing various mixed-valent cation dopants is a common practice to improve the cathode performance in solid oxide fuel cells. A computational procedure is developed in this work to predict the equilibrium oxygen vacancy non-stoichiometric concentrations at experimentally relevant temperatures and oxygen partial pressures for both bulk and surface oxide phases. The calculations are based on the first-principles density functional theory and a constrained free-energy functional. Quantitative agreements are found by direct comparisons to the thermogravimetry and solid electrolyte coulometry measurements for the strontium-doped lanthanum cobalt iron oxides at different compositions. Our results indicate that the oxygen vacancies are energetically stabilized at surfaces for all temperatures and all oxygen partial pressures, while such surface stabilization effects become stronger at higher temperatures and lower oxygen partial pressures.

  7. Diffusion in single crystals of melilite. I - Oxygen

    NASA Astrophysics Data System (ADS)

    Yurimoto, Hisayoshi; Morioka, Masana; Nagasawa, Hiroshi

    1989-09-01

    Oxygen-diffusion coefficients in melilite lattices were estimated by analyzing the structure of O-18 profiles determined in single crystals of gehlenite using SIMS. The lattice diffusion O-coefficients were found to be 2 to 4 orders of magnitude lower than those previously reported by Hayashi and Muehlenbachs (1986) for melilite solid solutions. The reason for these high diffusion rates in melilite solid solutions and the heterogeneous distribution of oxygen isotopes in the Allende Ca, Al-rich inclusions (CAIs) was investigated considering the contribution of fast diffusion along dislocations and possible changes in diffusion rate with gehlenite-akermanite ratios in melilite; the oxygen diffusion coefficients along dislocations were calculated by analyzing 'tailing' of the O-diffusion profiles. The results suggest that it is unlikely that the O-isotope differences in the Allende CAI minerals are the result of diffusion processes during a postcrystallization thermal event.

  8. Energetic Metastable Oxygen and Nitrogen Atoms in the Terrestrial Atmosphere

    NASA Technical Reports Server (NTRS)

    Kharchenko, Vasili

    2004-01-01

    We have investigated the impact of hot metastable oxygen atoms on the product yields and rate coefficients of atmospheric reactions involving O( (sup 1)D). The contribution of the metastable oxygen atoms to the thermal balance of the terrestrial atmosphere between 50 and 200 km has been determined. We found that the presence of hot O((sup l)D) atoms in the mesosphere and lower thermosphere significantly increases the production rate of the rotationally-vibrationally excited NO molecules. The computed yield of the NO molecules in N2O+ O((sup 1)D) atmospheric collisions, involving non-Maxwellian distributions of the metastable oxygen atoms, is more than two times larger than the NO-yield at a thermal equilibrium. The calculated non-equilibrium rate and yield functions are important for ozone and nitrous oxide modeling in the stratosphere, mesosphere and lower thermosphere.

  9. Oxygen isotope corrections for online ?34S analysis

    USGS Publications Warehouse

    Fry, B.; Silva, S.R.; Kendall, C.; Anderson, R.K.

    2002-01-01

    Elemental analyzers have been successfully coupled to stable-isotope-ratio mass spectrometers for online measurements of the ?34S isotopic composition of plants, animals and soils. We found that the online technology for automated ?34S isotopic determinations did not yield reproducible oxygen isotopic compositions in the SO2 produced, and as a result calculated ?34S values were often 1–3‰ too high versus their correct values, particularly for plant and animal samples with high C/S ratio. Here we provide empirical and analytical methods for correcting the S isotope values for oxygen isotope variations, and further detail a new SO2-SiO2 buffering method that minimizes detrimental oxygen isotope variations in SO2.

  10. Oxygen isotope corrections for online delta(34)S analysis.

    PubMed

    Fry, Brian; Silva, Steven R; Kendall, Carol; Anderson, Richard K

    2002-01-01

    Elemental analyzers have been successfully coupled to stable-isotope-ratio mass spectrometers for online measurements of the delta(34)S isotopic composition of plants, animals and soils. We found that the online technology for automated delta(34)S isotopic determinations did not yield reproducible oxygen isotopic compositions in the SO(2) produced, and as a result calculated delta(34)S values were often 1-3 per thousand too high versus their correct values, particularly for plant and animal samples with high C/S ratio. Here we provide empirical and analytical methods for correcting the S isotope values for oxygen isotope variations, and further detail a new SO(2)-SiO(2) buffering method that minimizes detrimental oxygen isotope variations in SO(2). PMID:11948816

  11. Origin of dramatic oxygen solute strengthening effect in titanium

    NASA Astrophysics Data System (ADS)

    Yu, Qian; Qi, Liang; Tsuru, Tomohito; Traylor, Rachel; Rugg, David; Morris, J. W.; Asta, Mark; Chrzan, D. C.; Minor, Andrew M.

    2015-02-01

    Structural alloys are often strengthened through the addition of solute atoms. However, given that solute atoms interact weakly with the elastic fields of screw dislocations, it has long been accepted that solution hardening is only marginally effective in materials with mobile screw dislocations. By using transmission electron microscopy and nanomechanical characterization, we report that the intense hardening effect of dilute oxygen solutes in pure ?-Ti is due to the interaction between oxygen and the core of screw dislocations that mainly glide on prismatic planes. First-principles calculations reveal that distortion of the interstitial sites at the screw dislocation core creates a very strong but short-range repulsion for oxygen that is consistent with experimental observations. These results establish a highly effective mechanism for strengthening by interstitial solutes.

  12. Climate Change Calculator

    NSDL National Science Digital Library

    This calculator allows users to calculate their ecological footprint in terms of trees required to sequester the carbon from carbon dioxide emissions produced by household use and transportation. Exact emissions figures or national averages can entered into the calculator, and the amount of carbon dioxide generated by burning of fossil fuels is calclulated, as well as the number of trees it will take to remove that amount of carbon dioxide.

  13. Calculator Java Applet

    NSDL National Science Digital Library

    This applet is a handy scientific calculator with the ability to do unit conversions on the fly. When you click on the link below, it will pop up in its own window so you can continue browsing after loading the calculator. The calculator window is resizable and will pop up to your preferred size after you close it once and come back to this page again.

  14. Radioactive Decay Calculator

    NSDL National Science Digital Library

    Alan Enns

    This online calculator computes radioactive decay, timed decay, and timed solid disposal for a databank containing 116 isotopes. It also features University of British Columbia disposal limits and a unit converter and date/time calculators. These tools calculate the half-life for selected isotopes; radioactive decay final activity, given the initial activity and decay time; the decay time, given the initial and final activities; and the decay time, given the mass of a solid and the initial activity.

  15. Multiphase flow calculation software

    DOEpatents

    Fincke, James R. (Idaho Falls, ID)

    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.

  16. Fluorescence-lifetime-based sensors: oxygen sensing and other biomedical applications

    NASA Astrophysics Data System (ADS)

    Randers-Eichhorn, Lisa; Bartlett, Roscoe A.; Sipior, Jeffrey; Frey, Douglas D.; Carter, Gary M.; Lakowicz, Joseph R.; Rao, Govind

    1996-05-01

    Murine hybridomas were cultivated in tissue culture flasks. Dissolved oxygen tensions in the gas and liquid phases during cell growth were measured non-invasively by an optical oxygen sensor. Readings were made with caps both cracked open and completely closed. During cell growth, gas phase oxygen concentrations remained near atmospheric levels, while the oxygen tension at the bottom of the flasks eventually reached zero. These results suggest that the widespread practice of cracking open tissue culture flask caps during cell growth with a view to supplying adequate oxygen to cells is ineffective and unnecessary. The mass transfer characteristics of the tissue culture flask indicate the dominant resistance to oxygen mass transfer to the cells was the liquid media. The mass transfer rates through the liquid layer under standard laboratory conditions were found to be greater than those predicted by diffusion alone, suggesting microscale mixing. Volumetric and specific oxygen consumption rates were calculated from the sensor data, and were comparable to published values. A recently developed single fiber optic oxygen sensor is described. This new sensor will provide oxygen concentrations at various levels in the tissue culture flasks, allowing more accurate modeling of oxygen diffusion.

  17. EVALUATING AN INNOVATIVE OXYGEN SENSOR FOR REMOTE SUBSURFACE OXYGEN MEASUREMENTS

    SciTech Connect

    Millings, M; Brian Riha, B; Warren Hyde, W; Karen Vangelas, K; Brian02 Looney, B

    2006-10-12

    Oxygen is a primary indicator of whether anaerobic reductive dechlorination and similar redox based processes contribute to natural attenuation remedies at chlorinated solvent contaminated sites. Thus, oxygen is a viable indicator parameter for documenting that a system is being sustained in an anaerobic condition. A team of researchers investigated the adaptation of an optical sensor that was developed for oceanographic applications. The optical sensor, because of its design and operating principle, has potential for extended deployment and sensitivity at the low oxygen levels relevant to natural attenuation. The results of the research indicate this tool will be useful for in situ long-term monitoring applications, but that the traditional characterization tools continue to be appropriate for characterization activities.

  18. Make Liquid Oxygen in Your Class

    ERIC Educational Resources Information Center

    French, M. M. J.; Hibbert, Michael

    2010-01-01

    Oxygen is one of the component gases of air at room temperature, making up around 20% of the atmosphere. But can oxygen be liquified? This article details a method for making small amounts of liquid oxygen in the classroom if there is no access to a cylinder of compressed oxygen gas, and two methods for identifying the fact that it is liquid…

  19. OXYGEN ADSORPTION ON NITROGEN CONTAINING CARBON SURFACES

    E-print Network

    Truong, Thanh N.

    OXYGEN ADSORPTION ON NITROGEN CONTAINING CARBON SURFACES Alejandro Montoya, Jorge O. Gil, Fanor-rich site of the carbon basal plane of graphite and then, it dissociates into oxygen atoms.1,2 Oxygen atoms at the edge of the carbon surface can form covalent bonds with oxygen. These sites can chemisorb

  20. Advanced oxygen sensor with oxide electrode materials

    Microsoft Academic Search

    Pavel Shuk; Robert Jantz; Ulrich Guth

    2011-01-01

    Calcium doped lanthanum and yttrium manganite electrode materials with oxygen deficiency and low polarization resistance (<30?cm2 at 600°C) were tested in new advanced electrochemical sensor for the oxygen measurements. Oxygen sensor with oxide electrodes was showing fast response (t95?5s at 600°C), good reproducibility (±0.04% O2) and long term stability at different oxygen concentration.