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1

Armalcolite - an oxygen fugacity indicator  

Microsoft Academic Search

Lunar armaloclites, (Fe, Mg)Ti2O5, contain appreciable amounts of Ti(3+) (less than 1 to 17% of Ti mole fraction). This is a function of the oxygen fugacity occurring at the time of its formation, with lower fugacities being reflected in higher Ti(3+) contents. Controlled cooling-rate and isothermal experimentation on synthetic analog and natural specimens of 70017 and 74275 have been used

F. T. Stanin; L. A. Taylor

1980-01-01

2

Review of Fugacity Calculations to Environmental Modelling.  

National Technical Information Service (NTIS)

Much effort has been devoted to understanding the mechanisms by which chemicals are transformed and transported in the environment. The objective of this work was to review fugacity calculations to environmental modeling. The fugacity calculations can be ...

L. Uotila

2002-01-01

3

Microprobe and Oxygen Fugacity Study of Armalcolite.  

National Technical Information Service (NTIS)

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 condit...

J. J. Friel

1976-01-01

4

Upper mantle oxygen fugacity recorded by spinel lherzolites  

NASA Astrophysics Data System (ADS)

Oxygen fugacity measurements were made for upper mantle spinel-lherzolite zenoliths entrained in alkaline magmas. The measurements were performed by determining the Fe3O4 (magnetite) fraction of MgAl2O4-rich synthetic spinel and using the data to project the thermobarometric fugacities for three-phase olivine-orthopyroxene-spinel. The calculated fugacities, corrected for 15 kbar pressure, were colocated or above those of the quartz-fayalite-magnetite buffer, which implies that the shallow upper mantle has a fugacity signature that is not in equilibrium with the metallic core. It is concluded that CO2 and H2O, not CH4 and H2, dominate the C-H-O system gaseous species. It is noted that the results do not preclude the possibility of low fugacity zones at a greater depth or formation of the mantle at a greater interval in the past.

Mattioli, G. S.; Wood, B. J.

1986-08-01

5

Oxygen Fugacities Directly Measured in Magmatic Gases  

Microsoft Academic Search

An electrochemical device was used to measure the fugacity of oxygen (fo_{2}) in holes drilled through the crust of Makaopuhi lava lake, Kilauea Volcano, Hawaii. Results obtained within 6 months of the lake formation show that log fo_{2} normally varies linearly with the reciprocal of the absolute temperature, and that chemical changes occurring in the cooling tholeiitic basalt are reflected

Motoaki Sato; Thomas L. Wright

1966-01-01

6

Dependence of Dunite Viscosity on Oxygen Fugacity  

NASA Astrophysics Data System (ADS)

Although the viscosity of olivine single crystals exhibits a clear dependence on oxygen fugacity, published results for polycrystalline, olivine-rich aggregates are more ambiguous. Based on deformation experiments on single crystals of olivine (Bai, Mackwell, and Kohlstedt, 1991), strain rate increases as oxygen fugacity to the -0.03 to 0.4 power, the exact value depending on factors such as crystal orientation and oxide buffer condition. In experiments on Å heim and Anita Bay dunite (Chopra and Paterson, 1981), samples jacketed in Ni tended to flow at lower differential stress than samples jacketed in Fe. An understanding of the dependence of oxygen fugacity on dunite will allow extrapolation of flow properties for a variety of mantle conditions. In the present study, samples were cored from blocks of Å heim dunite. The samples were annealed for twelve hours prior to deformation in a one-atmosphere horizontal furnace at an oxygen partial pressure either near the Ni/NiO or the Fe/FeO buffer to drive off water bound in hydrous minerals and water adsorbed at free surfaces. The silica activity is buffered by the presence of orthopyroxene. Samples were then deformed in a gas-medium apparatus at a confining pressure of 300 MPa and a temperature range of 1400 to 1550 K at a series of constant stress conditions. The resulting stress exponent was in the range of 3 to 4 indicating that deformation was dominated by dislocation creep. Samples buffered by Ni/NiO deformed a factor of 5 to 10 faster than samples buffered by Fe/FeO. Analyses of the results yield an oxygen fugacity exponent of approximately 0.2. Therefore, since oxygen fugacity in the mantle is believed to have increased through time, the viscosity of the mantle would likely have decreased.

Keefner, J. W.; Mackwell, S.

2004-12-01

7

Oxygen fugacities directly measured in magmatic gases  

USGS Publications Warehouse

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

Sato, M.; Wright, T. L.

1966-01-01

8

Oxygen fugacities directly measured in magmatic gases.  

PubMed

An electrochemical device was used to measure the fugacity of oxygen (fo(o2)) in holes drilled through the crust of Makaopuhi lava lake, Kilauea Volcano, Hawaii. Results obtained within 6 months of the lake formation show that log fo(o2) normally varies linearly with the reciprocal of the absolute temperature, and that chemical changes occurring in the cooling tholeiitic basalt are reflected in the fo(o2) values measured in the holes. PMID:17737588

Sato, M; Wright, T L

1966-09-01

9

Oxygen fugacity and piston cylinder capsule assemblies  

NASA Astrophysics Data System (ADS)

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

Jakobsson, S.

2011-12-01

10

The color of meteoritic hibonite - an indicator of oxygen fugacity  

NASA Astrophysics Data System (ADS)

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.

Ihinger, P. D.; Stolper, E.

1986-05-01

11

Iron-Titanium Oxides and Oxygen Fugacities in Volcanic Rocks  

Microsoft Academic Search

It is shown that in silicate liquids the ferric-ferrous equilibrium is controlled by temperature, oxygen fugacity, and the composition of the liquid, particularly its alkali content. Thus, if the iron-titanium oxide minerals that precipitate from a silicate liquid reflect the ferricferrous equilibrium, the oxygen geobarometer of Buddington and Lindsley will have to be calibrated, especially for such volcanics as phonolites

I. S. E. Carmichael; J. Nicholls

1967-01-01

12

Experimental data on the speciation of sulfur as a function of oxygen fugacity in basaltic melts  

Microsoft Academic Search

The speciation of sulfur as a function of oxygen fugacity was calculated in glasses of basaltic composition saturated experimentally with either sulfide or sulfate phases. The experiments were conducted on mixtures of synthetic and natural materials equilibrated at 1300 °C and 1 GPa in a piston-cylinder apparatus. Sulfur speciation was calculated by measuring the peak shift of the sulfur K?

Pedro J. Jugo; Robert W. Luth; Jeremy P. Richards

2005-01-01

13

Oxygen fugacity of the diamond +CO fluid assemblage and CO2 fugacity at 8 GPa  

Microsoft Academic Search

We have bracketed the oxygen fugacity (fO2) of the diamond +C-O fluid buffer (CCO) relative to the wuestite-magnetite (WM) and nickel-nickel oxide (NNO) buffers at 8 GPa and 950-1550 C using a Walker-style multi-anvil press. The intersection of CCO with WM is between 1050 and 1150 C and thus the log fO2 of CCO at 1100 C is constrained to

Tom Latourrette; John R. Holloway

1994-01-01

14

Experimental Control of Oxygen Fugacities by Graphite-Gas Equilibriums  

Microsoft Academic Search

Control of oxygen fugacities in a CO2 + CO atmosphere has been established experimentally by using a solid-phase buffer technique. Equilibration between the buffer and the enclosed sample is established by diffusion of the gas atmosphere through the buffer. The establishment of equilibrium by this method is indicated by the reversibility of experimental results in a study of the decomposition

Bevan M. French; Hans P. Eugster

1965-01-01

15

System Controls and Measures Oxygen Fugacity: Ceramic-electrolyte cell monitors the oxygen fugacity in high-temperature reactions.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. A system controls and measures oxygen fugacity in high-temperature chemical research. A ceramic-electrolyte cell is the sensing element. All the hardware needed to c...

1982-01-01

16

Oxygen Fugacity Buffers at Conditions of the Deep Earth  

NASA Astrophysics Data System (ADS)

Oxygen fugacity, a proxy for the chemical potential of oxygen, not only drives redox reactions, element partitioning and structural phase transitions, but also controls some transport and rheological properties, especially in minerals like silicates and oxides in which oxygen vacancies can play a large role. Therefore, the importance of oxygen fugacity in the deep Earth can hardly be overstated. In this study we have constructed oxygen fugacity buffers for the metal-oxide systems Fe-FeO, Ni-NiO, and Re-ReO2 at high pressures and temperatures, extending to the conditions of the lower mantle. Pressure-volume-temperature relations for the Fe-FeO, Ni-NiO, and Re-ReO2 metal-oxide pairs were measured by synchrotron X-ray diffraction in both a multi-anvil press and a laser heated diamond anvil cell. Simultaneous measurement of both the metal and its oxide provided a measure of the volume difference between the two phases that is more precise than comparisons between independently determined equations of state. This allows more precise evaluation of the thermodynamics of the metal-oxide system, including oxygen fugacity buffer curves at high pressure. Nonstoichiometric effects in wustite were eliminated by high-PT equilibration with Fe, allowing the equation of state of stoichiometric FeO to be measured. We show that the differences (in log fO2 units) between the IW and NNO buffers, and also between the IW and RRO buffers, decrease significantly with increasing pressure. These results can augment our understanding of metal-silicate partitioning at high pressures, for example, and form a basis for further investigations into the redox state of the deep Earth.

Campbell, A. J.; Danielson, L. R.; Righter, K.; Seagle, C. T.; Wang, Y.; Prakapenka, V. B.

2007-12-01

17

The color of meteoritic hibonite - an indicator of oxygen fugacity  

Microsoft Academic Search

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

P. D. Ihinger; E. Stolper

1986-01-01

18

Oxygen isotope diffusion and zoning in diopside: The importance of water fugacity during cooling  

SciTech Connect

The oxygen isotope ratio of diopside correlates with crystal size in many high grade marbles, permitting the intracrystalline self-diffusion rate of oxygen in diopside to be empirically evaluated. Small (75--300 {micro}m) and large (1.2--1.5 mm) diopside grains were analyzed in bulk for their oxygen isotope ratios by laser extraction. Cooling histories were calculated using the Fast Grain Boundary diffusion model, assuming equilibrium at peak metamorphic temperatures (700--800 C), slow cooling of 1.5--4 C/Ma, and experimentally determined diffusion coefficients for oxygen in minerals. Measurements and calculations to predict differences in {delta}{sup 18}O between large and small diopside grains lead to the following conclusions. (1) Natural diopsides in this study exhibit variations in oxygen isotope ratios between grains of different size, which are related to the peak temperature, cooling rate, and water fugacity during cooling. Diffusion distances are properly modeled by the size of an entire grain; there is no evidence for subdomains. (2) In slowly cooled high grade metamorphic terrains, water fugacity can be highly variable from rock to rock during cooling. For many rocks, water fugacity is the most important constraint on the degree of oxygen isotope retrograde exchange.

Edwards, K.J.; Valley, J.W. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Geology and Geophysics

1998-07-01

19

The effect of hydrogen, oxygen, and water fugacity on oxygen diffusion in alkali feldspar  

SciTech Connect

Oxygen self-diffusion in adularia and albite single crystals was studied hydrothermally at 650{degree}C from 5 to 1,500 MPa confining pressure using a combination of hydrogen/oxygen buffers, a hydrogen ion buffer, and variable mole fractions of water (dilution with CO{sub 2}). Diffusion coefficients (D) were determined from {sup 18}O concentration profiles measured with an ion microprobe. There is a good correlation of the D values with water fugacity but not with oxygen fugacity, hydrogen fugacity, hydrogen ion concentration, nor confining pressure over the range for which these parameters could be fixed independent of the water fugacity. Oxygen diffusion must involve the transport of an oxygen-bearing species, and the results of this study suggest that the transport species is molecular water. The rate-limiting step for oxygen diffusion could be either the rate of migration of the molecular water in the crystal or the rate of exchange of its oxygen with the feldspar structure. While protons may play a role in the mechanism of oxygen diffusion in feldspar, above the concentration supplied by pure water additional protons have no measurable effect on diffusion rates.

Farver, J.R.; Yund, R.A. (Brown Univ., Providence, RI (USA))

1990-11-01

20

Low oxygen fugacity dependency for the deformation of partially molten lherzolite  

NASA Astrophysics Data System (ADS)

We present the results of an experimental investigation of the influence of oxygen fugacity on the deformation of a partially molten spinel lherzolite using a 0.1 MPa gas-media creep rig under temperatures of 1160–1190 °C, stresses of 4–74 MPa and well-controlled oxygen fugacities of 10? 7 to 10? 11 MPa. The partially molten spinel lherzolite was deformed by a dislocation-mediated creep process such as dislocation creep or dislocation-accommodated grain boundary sliding (DGBS) (n = 3.5 ± 0.3) as well as in the diffusion creep regime (n = 1.2 ± 0.2). The average oxygen fugacity exponent of lherzolite is 0.04 ± 0.02, which is significantly smaller than the values measured for olivine single crystals (0.10–0.36) and dunite rocks (0.20) deformed by dislocation creep. We attribute the low oxygen fugacity exponent of partially molten lherzolite samples either to the operation of grain boundary sliding, if DGBS dominates the deformation, or to the presence of pyroxenes whose deformation has a weak or no dependency on oxygen fugacity, if dislocation creep dominates the deformation. In the latter case, the oxygen fugacity exponent decreases rapidly with decreasing volume fraction of olivine. The low oxygen fugacity exponent for our partially molten lherzolite samples implies that dislocation creep or DGBS of mantle peridotite will most likely be insensitive to variations of oxygen fugacity in the upper mantle.

Wang, Yongfeng; Zhang, Junfeng; Jin, Zhenmin; Kohlstedt, David L.

2012-12-01

21

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

USGS Publications Warehouse

Volcanic gases collected during episode 1 of the Puu Oo eruption along the east rift zone of Kilauea Volcano, Hawaii, have uniform C-O-H-S-Cl-F compositions that are sharply depleted in CO2. The CO2-poor gases are typical of Type II volcanic gases (gerlach and Graeber, 1985) and were emitted from evolved magma stored for a prolonged period of time in the east rift zone after releasing CO2-rich gases during an earlier period of temporary residence in the summit magma chamber. The samples are remarkably free of contamination by atmospheric gases and meteoric water. Thermodynamic evaluation of the analytical data shows that the episode 1 gases have equilibrium compositions appropriate for temperatures between 935 and 1032??C. Open- and closed-system equilibrium models of species distributions for the episode 1 gases show unequivocally that coexisting lavas buffered the gas oxygen fugacities during cooling. These models indicate that the fO2 buffering process occurs by transfer of oxygen from the major species in the gas phase (H2O, CO2, SO2) to the lava during cooling and that the transfer of oxygen also controls the fugacities of several minor and trace species (H2, CO, H2S, S2, Cl2, F2), in addition to O2 during cooling. Gas/lava exchanges of other components are apparently insignificant and exert little influence, compared to oxygen exchange, during cooling. Oxygen transfer during cooling is variable, presumably reflecting short-term fluctuations in gas flow rates. Higher flow rates restrict the time available for gas/lava oxygen transfer and result in gases with higher equilibrium temperatures. Lower flow rates favor fO2-constrained equilibration by oxygen transfer down to lower temperatures. Thus, the chemical equilibrium preserved in these gases is a heterogeneous equilibrium constrained by oxygen fugacity, and the equilibrium temperatures implied by the compositions of the gases reflect the temperatures at which gas/lava oxygen exchange ceased. This conclusion challenges the common assumption that volcanic gases are released from lava in a state of chemical equilibrium and then continue equilibrating homogeneously with falling temperature until reaction rates are unable to keep pace with cooling. No evidence is found, moreover, that certain gas species are kinetically more responsive and able to equilibrate down to lower temperatures than those of the last gas/lava oxygen exchange. Homogeneous reaction rates in the gas phase are apparently slow compared to the time it took for the gases to move from the last site of gas/lava equilibration to the site of collection. An earlier set of data for higher temperature CO2-rich Type I volcanic gases, which come from sustained summit lava lake eruptions supplied by magma that experienced substantially shorter periods of crustal storage, shows fO2 buffering by oxygen transfer up to 1185??C. Oxygen fugacity measurements in drill holes into ponded lava flows suggest that buffering by oxygen transfer may control the fO2 of residual gases down to several hundred degrees below the solidus in the early stages of cooling. Although the details of the fO2 buffering mechanisms for oxygen transfer are unknown, the fact that fO2 buffering is effective from molten to subsolidus conditions suggests that the reaction mechanisms must change with cooling as the reactants change from predominantly melt, to melt plus crystals, to glass plus crystals. Mass balance calculations suggest that redox reactions between the gas and ferrous/ferric iron in the lava are plausible mechanisms for the oxygen transfer and that the fO2 of the gases is buffered by sliding ferrous/ferric equilibria in the erupting lavas. Contrary to expectations based on models predicting the oxidation of basalt by H2 and CO escape during crustal storage, CO2-rich Type I gases and CO2-poor Type II gases have identical oxygen fugacities despite greatly different crustal storage and degassing histories. Volcanic gas data give a tightly co

Gerlach, T. M.

1993-01-01

22

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

NASA Astrophysics Data System (ADS)

Volcanic gases collected during episode 1 of the Puu Oo eruption along the east rift zone of Kilauea Volcano, Hawaii, have uniform C-O-H-S-Cl-F compositions that are sharply depleted in CO 2. The CO 2-poor gases are typical of Type II volcanic gases ( GERLACH and GRAEBER, 1985) and were emitted from evolved magma stored for a prolonged period of time in the east rift zone after releasing CO 2-rich gases during an earlier period of temporary residence in the summit magma chamber. The samples are remarkably free of contamination by atmospheric gases and meteoric water. Thermodynamic evaluation of the analytical data shows that the episode 1 gases have equilibrium compositions appropriate for temperatures between 935 and 1032°C. Open- and closed-system equilibrium models of species distributions for the episode 1 gases show unequivocally that coexisting lavas buffered the gas oxygen fugacities during cooling. These models indicate that the fO2 buffering process occurs by transfer of oxygen from the major species in the gas phase (H 2O, CO 2, SO 2) to the lava during cooling and that the transfer of oxygen also controls the fugacities of several minor and trace species (H 2, CO, H 2S, S 2, Cl 2, F 2), in addition to O 2 during cooling. Gas/lava exchanges of other components are apparently insignificant and exert little influence, compared to oxygen exchange, during cooling. Oxygen transfer during cooling is variable, presumably reflecting short-term fluctuations in gas flow rates. Higher flow rates restrict the time available for gas/lava oxygen transfer and result in gases with higher equilibrium temperatures. Lower flow rates favor fO2-constrained equilibration by oxygen transfer down to lower temperatures. Thus, the chemical equilibrium preserved in these gases is a heterogeneous equilibrium constrained by oxygen fugacity, and the equilibrium temperatures implied by the compositions of the gases reflect the temperatures at which gas/lava oxygen exchange ceased. This conclusion challenges the common assumption that volcanic gases are released from lava in a state of chemical equilibrium and then continue equilibrating homogeneously with falling temperature until reaction rates are unable to keep pace with cooling. No evidence is found, moreover, that certain gas species are kinetically more responsive and able to equilibrate down to lower temperatures than those of the last gas/lava oxygen exchange. Homogeneous reaction rates in the gas phase are apparently slow compared to the time it took for the gases to move from the last site of gas/lava equilibration to the site of collection. An earlier set of data for higher temperature CO 2-rich Type I volcanic gases, which come from sustained summit lava lake eruptions supplied by magma that experienced substantially shorter periods of crustal storage, shows fO2 buffering by oxygen transfer up to 1185°C. Oxygen fugacity measurements in drill holes into ponded lava flows suggest that buffering by oxygen transfer may control the fO2 of residual gases down to several hundred degrees below the solidus in the early stages of cooling. Although the details of the fO2 buffering mechanisms for oxygen transfer are unknown, the fact that fO2 buffering is effective from molten to subsolidus conditions suggests that the reaction mechanisms must change with cooling as the reactants change from predominantly melt, to melt plus crystals, to glass plus crystals. Mass balance calculations suggest that redox reactions between the gas and ferrous/ferric iron in the lava are plausible mechanisms for the oxygen transfer and that the fO2 of the gases is buffered by sliding ferrous/ferric equilibria in the erupting lavas. Contrary to expectations based on models predicting the oxidation of basalt by H 2 and CO escape during crustal storage, CO 2-rich Type I gases and CO 2-poor Type II gases have identical oxygen fugacities despite greatly different crustal storage and degassing histories. Volcanic gas data give a tightly constrained log fO2 of NNO - 0.5 (±0.05) for subaerially erupted Kilauea basalt

Gerlach, T. M.

1993-02-01

23

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

Microsoft Academic Search

A decomposition\\/reformation process that uses a high oxygen fugacity (2 MPa) heat treatment followed by low oxygen fugacity (<1 MPa) annealing was applied to silver-sheathed Bisb2Srsb2CaCusb2Osb{8±delta} (Bi-2212) tapes. The rate at which the Bi-2212 phase reforms was studied using X-ray diffractometry and image analyses. The kinetic data was fitted to an Avrami-type equation and was found to be consistent with

John J. Gannon Jr.

1998-01-01

24

Electrochemical manipulation of apparent oxygen fugacity in a piston cylinder apparatus  

Microsoft Academic Search

Phase stability of mineral assemblages and their physical properties, especially transport properties, are influenced by oxygen fugacity. Redox effects in earth and planetary systems at high pressure include setting of ferric\\/ferrous iron ratios [controlling the electrical conductivity of crustal and mantle materials] and possible chemical reactions at the Earth's core-mantle boundary. Experimental controls of oxygen fugacity in high-pressure devices have

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

2002-01-01

25

Platinum catalytic effect on oxygen fugacity of CO 2?H 2 gas mixtures measured with ZrO 2 oxygen sensor at 105 Pa from 1300 to 700°C  

Microsoft Academic Search

The oxygen fugacity of CO2?H2 gas mixtures were measured with a ZrO2 oxygen sensor at high temperatures in a furnace. We confirmed that the oxygen fugacity values measured by the ZrO2 cell are more reducing than those of the CO2?H2 gas mixtures calculated by using JANAF data at temperatures below 1150°C as was previously reported by Huebner (1975). We successfully

M. Miyamoto; T. Mikouchi

1996-01-01

26

Oxygen diffusion in olivine: Effect of oxygen fugacity and implications for creep  

Microsoft Academic Search

Oxygen self-diffusion experiments on single crystals of San Carlosolivine (\\/similar to\\/Foââ) at 1200\\/degree\\/less than or equal to\\/ital T\\/less than or equal to1400 \\/degree\\/C, oxygen fugacities(\\/ital f\\/\\/sub O2\\/) along the Ni-NiO and Fe-FeO buffers, and silica activityat the olivine-orthopyroxene buffer yielded results that follow therelationship \\/ital D\\/=2.6\\/times\\/10\\/sup \\/minus\\/10\\/\\/ital f\\/ \\/sub O2\\/\\/sup 0.21+-0.03\\/ exp (\\/minus\\/266+-11)(kJ mol\\/sup \\/minus\\/1\\/\\/\\/ital RT\\/), where\\/ital D\\/ is the

F. J. Ryerson; W. B. Durham; D. J. Cherniak; W. A. Lanford

1989-01-01

27

Fugacity of Gaseous Hydrogen.  

National Technical Information Service (NTIS)

The concept of fugacity is explained. Application of compressibility and fugacity data in hydrogen embrittlement calculations is discussed. Equations of state are reviewed. Compressibility factors and fugacity coefficients are calculated.

H. P. Vanleeuwen

1983-01-01

28

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

Microsoft Academic Search

It is suggested that major variations in the relative oxygen fugacity of a basaltic magma are caused primarily by gas-forming elements, especially carbon and hydrogen. According to this theory, carbon, present in the source region of a basaltic magma, reduces the host magma during ascent, as isothermally carbon becomes more reducing with decreasing pressure. For an anhydrous magma such as

Motoaki Sato

1978-01-01

29

The Aurora volcanic field, California-Nevada: oxygen fugacity constraints on the development of andesitic magma  

NASA Astrophysics Data System (ADS)

The Aurora volcanic field, located along the northeastern margin of Mono Lake in the Western Great Basin, has erupted a diverse suite of high-K and shoshonitic lava types, with 48 to 76 wt% SiO2, over the last 3.6 million years. There is no correlation between the age and composition of the lavas. Three-quarters of the volcanic field consists of evolved (<4 wt% MgO) basaltic andesite and andesite lava cones and flows, the majority of which contain sparse, euhedral phenocrysts that are normally zoned; there is no evidence of mixed, hybrid magmas. The average eruption rate over this time period was ˜200 m3/km2/year, which is typical of continental arcs and an order of magnitude lower than that for the slow-spreading mid-Atlantic ridge. All of the Aurora lavas display a trace-element signature common to subduction-related magmas, as exemplified by Ba/Nb ratios between 52 and 151. Pre-eruptive water contents ranged from 1.5 wt% in plagioclase-rich two-pyroxene andesites to ˜6 wt% in a single hornblende lamprophyre and several biotite-hornblende andesites. Calculated oxygen fugacities fall within 0.4 and +2.4 log units of the Ni-NiO buffer. The Aurora potassic suite follows a classic, calc-alkaline trend in a plot of FeOT/MgO vs SiO2 and displays linear decreasing trends in FeOT and TiO2 with SiO2 content, suggesting a prominent role for Fe-Ti oxides during differentiation. However, development of the calc-alkaline trend through fractional crystallization of titanomagnetite would have caused the residual liquid to become so depleted in ferric iron that its oxygen fugacity would have fallen several log units below that of the Ni-NiO buffer. Nor can fractionation of hornblende be invoked, since it has the same effect as titanomagnetite in depleting the residual liquid in ferric iron, together with a thermal stability limit that is lower than the eruption temperatures of several andesites (˜1040 1080°C; derived from two-pyroxene thermometry). Unless some progressive oxidation process occurs, fractionation of titanomagnetite or hornblende cannot explain a calc-alkaline trend in which all erupted lavas have oxygen fugacites ? the Ni-NiO buffer. In contrast to fractional crystallization, closed-system equilibrium crystallization will produce residual liquids with an oxygen fugacity that is similar to that of the initial melt. However, the eruption of nearly aphryic lavas argues against tapping from a magma chamber during equilibrium crystallization, a process that requires crystals to remain in contact with the liquid. A preferred model involves the accumulation of basaltic magmas at the mantle-crust interface, which solidify and are later remelted during repeated intrusion of basalt. As an end-member case, closed-system equilibrium crystallization of a basalt, followed by equilibrium partial melting of the gabbro will produce a calc-alkaline evolved liquid (namely, high SiO2 and low FeOT/MgO) with a relative f O 2 (corrected for the effect of changing temperature) that is similar to that of the initial basalt. Differentiation of the Aurora magmas by repeated partial melting of previous underplates in the lower crust rather than by crystal fractionation in large, stable magma chambers is consistent with the low eruption rate at the Aurora volcanic field.

Lange, R. A.; Carmichael, Ian S. E.

1996-10-01

30

Czochralski growth of single-crystal fayalite under controlled oxygen fugacity conditionsl  

Microsoft Academic Search

Single-crystal boules of fayalite (FerSiOo) were grown in the temperature range 1165 to 1200'C at I bar total pressure from high-purity oxide melts of 1.95:l to 2.10:l Fe:Si atom ratio. A modified Czochralski technique was used, with platinum crucibles inductively heated under oxygen fugacities, \\/(Or), between l0-e and l0-'2 bar. The boules are up to l0 mm in diameter by

Cennrr B. FrNcH; G. WayNn Cram; Orro C. Kopp

31

Partitioning of Fe3+\\/Fetotal between amphibole and basanitic melt as a function of oxygen fugacity  

Microsoft Academic Search

We present the first microbeam measurements of Fe3+\\/Fetotal and H contents in amphiboles and glasses synthesized from a basanite at high temperature and pressure where oxygen fugacity (fO2) was buffered and water activity was monitored. The amphiboles were synthesized from basanite (San Carlos, AZ, USA) at 1100-1175°C and 1.5-2.0 GPa, at four fO2 values from the iron-wüstite (IW) buffer to

P. L. King; R. L. Hervig; J. R. Holloway; J. S. Delaney; M. D. Dyar

2000-01-01

32

Oxygen and Sulphur Fugacities of Magmatic Gases Directly Measured in Active Vents of Mount Etna  

Microsoft Academic Search

Solid-electrolyte sensors were used to measure the oxygen and sulphur fugacities of magmatic gases in vents located at an elevation of about 3170 m on the northeast flank of the NE crater of Mt Etna in July 1970. The temperature of the gas ranged from 773 to 1057 degrees C. The least-squares fit of 13 measured lg fo_{2} values yielded

M. Sato; J. G. Moore; A. T. Huntingdon; M. S. Beck

1973-01-01

33

Oxygen fugacity of gases and rocks from Momotombo volcano, Nicaragua: Application to volcanological monitoring  

Microsoft Academic Search

The oxygen fugacity (fO2) and the fO2 versus T°C relationship of high-temperature (600°-800°C) gas emissions from Momotombo volcano, Nicaragua, was determined from both field electrochemical measurements (electrolytic cell as- sembly) and thermodynamic computations on gas samples collected between 1978 and 1985. It was then compared with the intrinsic fO2 of fresh and altered lavas from the last eruption (1905), as

G. Benhamou; P. Allard; J. C. Sabroux; G. Vitter; D. Dajlevic; A. Creusot

1988-01-01

34

Variation in oxygen fugacity with depth in the upper mantle beneath the Kaapvaal craton, Southern Africa  

Microsoft Academic Search

Oxygen fugacity (fO2) is an important parameter in many geochemical processes in the Earth’s mantle. To assess how fO2 varies with depth, Fe3+ contents in garnet and spinel from peridotite xenoliths were determined by Mössbauer spectroscopy. A total of 49 xenoliths were investigated from localities on the southern flank of the Kaapvaal craton in South Africa (Kimberley, Jagersfontein, Frank Smith

A. B Woodland; M. Koch

2003-01-01

35

Metal-silicate partitioning of nickel and cobalt: The influence of temperature and oxygen fugacity  

Microsoft Academic Search

We report new metal-silicate melt partitioning experiments for Co and Ni. One atmosphere, gas-mixing (H 2 CO 2 or CO-CO 2 ) experiments were run at 1300, 1425, and 1550°C and at oxygen fugacities between air and near or below the iron-wüstite (IW) buffer. Bulk melt composition, at the diopsideanorthite-forsterite eutectic, was constant in all runs. Metals in these experiments

Christopher J. Capobianco; Anders A. Amelin

1994-01-01

36

Solubility of tungsten in a haplobasaltic melt as a function of temperature and oxygen fugacity  

Microsoft Academic Search

The solubility of tungsten (W) in a haplobasaltic melt has been determined as a function of oxygen fugacity in the temperature range 1300–1500°C using the mechanically assisted equilibrium technique of Dingwell et al. (1994), and at 1600–1700°C by the wire loop method. Quenched samples were analysed for W by using ICP-AES as well as INAA, and sample major element compositions

W. Ertel; H. St. C. O'Neill; D. B. Dingwell; B. Spettel

1996-01-01

37

Measurement of oxygen fugacities under reducing conditions: non-Nernstian behavior of Y 2O 3-doped zirconia oxygen sensors  

Microsoft Academic Search

A calibration procedure is presented for the use of a Y2O3-stabilized zirconia (YSZ) oxygen sensor in 1 atm gas-mixing furnaces in the temperature range 1200–1500°C and 0–8 orders of magnitude below the iron-wüstite (IW) buffer. Corrections to the Nernst equation were obtained by measuring apparent oxygen fugacities of gases in equilibrium with graphite (equilibrated with pure CO vapor), Cr +

R. A. MENDYBAEV; J. R. BECKETT; E Stolper; L. GROSSMAN

1998-01-01

38

Oxygen fugacity stratification of a magma chamber revealed by Mössbauer spectroscopy: evidence from the 1875 Askja eruption, N. Iceland  

Microsoft Academic Search

Mössbauer spectra of volcanic glasses from the 1875 Askja eruption reveals that the dacitemagma chamber was stratified in\\u000a oxygen fugacity. The eruption was triggered by basaltic magma which was intruded into the base of the chamber. The observed\\u000a oxidation state falls within the range of oxygen fugacities of H2O\\/CO2 mixtures at the liquidus temperature of the magma. It is concluded

Ö. Helgason; N. Oskarsson; G. E. Sigvaldason

1992-01-01

39

Complications in Determining Oxygen Fugacities From Olivine-Melt Equilibrium Illustrated by the Pu'u'O'o Lavas, Hawaii  

NASA Astrophysics Data System (ADS)

We have shown previously that oxygen fugacities calculated from olivine-melt equilibrium using rim compositions agree well with those calculated from analyzed Fe3+/?Fe for MORB and for Icelandic OIB (MORB - average ?FMQ -0.72 versus -0.70, Iceland average ?FMQ -0.49 versus -0.58). The agreement between oxygen fugacities calculated from Ol-melt equilibrium and those calculated from analyzed Fe3+/?Fe is excellent for individual samples of MORB from the FAMOUS region and Blanco Trough ( difference in calculated ?FMQ < 0.30). Published analyses of Fe3+/?Fe yield oxygen fugacilties of ?FMQ= -0.72±0.43 for lavas from Kilauea and Mauna Loa, and ?FMQ=0.91±0.72 for Loihi, very close to those for MORB. Oxygen fugacities determined using carefully selected Ol-melt analyses (?FMQ= -0.43±0.32) are in reasonable agreement with those determined from Fe3+/?Fe for Kilauea and Mauna Loa, and agreement between fO2 calculated from Ol-melt equilibrium (?FMQ= -0.26) and that calculated from Fe3+/?Fe (?FMQ= -0.64) is excellent for one sample from Kilauea. However, olivine-melt pairs from some samples, including those from the Pu'u'O'o lavas, yield anomalously high or low estimates of fO2 (average ?FMQ =-0.6907, range -4.07 to +0.34). We suggest that these anomalous values reflect the complex history of olivines in these lavas, in particular the effects of magma mixing. Some olivines in the Pu'u'O'o lavas clearly have rims that are anomalously rich in Fa, whereas others have rims that are anomalously rich in Fo and do not appear to have equilibrium compositions. Given the dependence of olivine composition on melt Fe3+/?Fe, there is no simple method to determine the equilibrium composition of olivine for a particular melt. However, detailed zoning profiles and analyses of microphenocrysts allow probable equilibrium compositions to be identified. We suggest that the average fO2 of Hawaiian lavas lies close to (?FMQ= -1) based on published results using spinel-melt equilibrium and Fe-Ni exchange between olivine and sulfide liquid. Olivine-glass inclusion data for Koolau samples also suggest (?FMQ= ~-1).

McCann, V. E.; Barton, M.; Thornber, C. R.

2005-12-01

40

Estimates of Oxygen Fugacity in the Basaltic Shergottites From Electron Microprobe Oxygen Analysis  

NASA Astrophysics Data System (ADS)

The basaltic shergottites consist of four meteorites thought to have a martian origin: Shergotty, Zagami, EETA 79001, and QUE 94201. All are basaltic in composition, but only QUE 94201 contains no cumulus pyroxene and may therefore represent a martian liquid. Previous estimates of fO2 at the time of crystallization of the shergottites range from the quartz-fayalite-magnetite (QFM) buffer to 4 log units below QFM, based on coexisting Fe-Ti oxides, for all but QUE94201. Oxygen fugacity conditions for QUE94201 are near the iron-wustite (IW) buffer about 4 log units below QFM. The current research aims to refine the estimates of fO2, for the basaltic shergottites, through electron microprobe techniques. The technique of quantitative analysis of fO2 using the electron micro-probe has been developed to the point where O can be analyzed with certainty comparable to the analysis of most cations. Practical application of the technique to naturally occurring spinels has been demonstrated demonstrated. A set of O standards now exists that can be readily obtained. The technique also allows an assessment of stoichiometry, since the cation total, on the basis of four O atoms, does not rely on the assumption of stoichiometry. Instead, the amount of Fe3(+), is determined by charge balance.

Herd, C. D. K.; Papike, J. J.

1998-01-01

41

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

SciTech Connect

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

Gerlach, T.M. (Geological Survey, Vancouver, WA (United States))

1993-02-01

42

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

SciTech Connect

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.

Righter, K.; Sutton, S.; Danielson, L.; Pando, K.; Le, L.; Newville, M. (Jacobs Engineering); (NASA JSC); (Hamilton Sundstrand); (UC)

2009-03-23

43

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

NASA Astrophysics Data System (ADS)

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

Gannon, John J., Jr.

44

Techniques for the Control of Water Fugacity and Oxygen Fugacity for Experimentation in Solid-Media High-Pressure Apparatus  

Microsoft Academic Search

Techniques for the encapsulation of H sO with sample in welded noble-metal containers have been used routinely in solid-media, high-pressure apparatus (e.g., the piston cylinder apparatus) since the early 1960's [e.g., Newton and Kennedy, 1963]. Recently, it has bedome desirable to regulate the fugacity of HsO 0H2o) at some value less than that which occurs in a vapor consisting of

A. L. Boettcher; B. O. Mysen; J. C. Allen

1973-01-01

45

Upper mantle oxidation state: Ferric iron contents of Iherzolite spinels by 57Fe Mössbauer spectroscopy and resultant oxygen fugacities  

NASA Astrophysics Data System (ADS)

The ferric iron contents of spinels from 30 spinel Iherzolite xenoliths have been measured by 57Fe Mössbauer spectroscopy. The samples are widely dispersed in geographic and tectonic setting, coming from Southwest United States (San Carlos, Kilbourne Hole), Japan (Ichinomegata), Massif Central, France (Mont Briançon) and Central Asia (Tariat Depression, Vitim Plateau). The total range of Fe 3O 4 contents of the spinels is from 1.7 to 5.2 mol% with an uncertainty of 0.2 to 0.3 mol%. These data were used to calculate the oxygen fugacities recorded by the spinel Iherzolites using the oxygen thermobarometer 6 Fe 2SiO 4 + O 2 = 3 Fe 2Si 2O 6 + 2 Fe 3O 4. olivine orthopyroxene spinel The Fe(III) contents of the spinels translate to oxygen fugacities which, at 15 kb, range between 1.7 log units below and 1.2 log units above FMQ using either the Mattioli and Wood (1988) or O'neill and Wall (1987) version of Fe 3O 4 activity. There are distinct regional differences ƒO 2, the specimens from SW U.S.A. and Central Asia exhibiting values from slightly above FMQ to 1.5 log units below FMQ. At an estimated pressure of 15 kb, these values overlap with the ƒO 2- T field of MORB glasses, indicating, in agreement with trace element abundances, that many of these samples are related to the MORB source region. Samples from Ichinomegata and Mont Briançon are all above the MORB range, however, suggesting progressive oxidation related to subduction processes. All of our samples give oxygen fugacities more than 2 log units above IW, implying that C?H?O fluids in the upper mantle are dominated by CO 2 and H 2O and that CH 4 is a minor (< 10%) component. A detailed comparison of Fe(III) contents determined by Mössbauer spectroscopy and those obtained from microprobe analysis indicates that the latter are sufficiently precise (± 0.002 fXFe3O 4) but, in general, too inaccurate for oxygen thermobarometry. Use of Mössbauer-analyzed spinels as microprobe standards enables accuracy to approach precision, however, and appropriate standards are available on request.

Wood, Bernard J.; Virgo, David

46

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

NASA Astrophysics Data System (ADS)

Amphibole is the hydrous metasomatic phase in spinel-bearing peridotites from Baker Rocks (Northern Victoria Land, Antartica). It occurs both as disseminated or veins in the spinel lherzolites. Both types derive from a continuous reaction between metasomatic melts and the pristine paragenesis of the continental lithospheric mantle beneath the Northern Victoria Land. In order to determine the effective role of water circulation during the metasomatic process and amphibole formation, six amphiboles were fully characterised. The accurate determination of the site population and dehydrogenation of these amphiboles was carried out through Single-Crystal X-ray diffraction, electron micropoble analyses (EMPA) and secondary ion mass spectroscopy (SIMS) on the same single crystal. The Fe3+/(Fe3+ + Fe2+)ratio was determined by X-ray Absorption Near Edge Spectrocopy (XANES) on amphibole powder. The measured (from SIMS) degree of dehydrogenation (O(3)O2-) is in the range 0.79-1.07 and in agreement with the calculated (from the M(1)-M(3) distance) values. The dehydrogenation is primary and ascribed to the Ti-oxy component of the amphibole, as suggested by the site populations; the post-crystallisation H loss is negligible. The aH2O of the Baker Rocks mantle lithosphere was calculated from the dehydration equilibrium among end-member components assuming that amphiboles are in equilibrium with the anhydrous peridotitic phases. The aH2O ranges from 0.0126 to 0.0545; a difference up to 60The oxygen fugacity of the Baker Rocks mantle xenoliths calculated on the anhydrous equilibria olivine-clinopyroxene-orthopyroxene-spinel is between -1.98 and -0.30 log units, below the fayalite-magnetite-quartz (FMQ) buffer. These results compare well with those obtained from the dissociation constant of water, which reflects the oxygen fugacity of the amphibole formation (Dlog fO2 between -2.5 and -0.6 log units). The metasomatic process is able to stabilize amphibole in an environment of low water activity and low redox conditions. Amphibole acts as the main H acceptor among the peridotite minerals and it may prevent fluid circulation and contribute to buffer the oxygen fugacity.The important issue of this study is that amphibole within the lithospheric mantle not always means high water activity and oxidizing conditions.

Bonadiman, Costanza; Nazzareni, Sabrina; Coltorti, Massimo; Comodi, Paola; Giuli, Gabriele; Faccini, Barbara

2013-04-01

47

Interdependence of phase chemistry, microstructure, and oxygen fugacity in titanate nuclear waste ceramics  

SciTech Connect

Titanate ceramic waste forms were prepared using several combinations of calcination atmosphere (N{sub 2}, N{sub 2} {minus} 3.5% H{sub 2},h{sub 2}) and metallic redox buffers (Ni,Fe,Ti,Al) to examine the dependence of microstructure and durability upon oxygen activity. It was found that the microstructures and phase assemblages were mostly insensitive to the fabrication method, although in detail systematic changes were recognized. The correlation of aqueous durability with oxygen fugacity was not straightforward because of density variations in the hot-pressed ceramics. These fluctuations in density dominated the dissolution characteristics of the waste forms and sometimes obscured the more subtle changes associated with redox potential. It is concluded that although the best durability is achieved at lower fugacities (i.e., Ti metal buffer and H{sub 2} calcination atmosphere), a satisfactory product can be produced using any of the preparative routes examined, provided the material is completely densified.

Buykx, W.J.; Levins, D.M.; Smith, K.L.; Stevens, G.T.; Watson, K.G.; White, T.J. (Advanced Materials Program, Australian Nuclear Science and Technology Organization, Menai, New South Wales 2234 (AU)); Smart, R. (School of Chemical Technology, South Australian Institute of Technology, Ingle Farm, South Australia 5098 (AU)); Weedon, D. (Julius Kruttschnitt Mineral Research Centre, University of Queensland, St. Lucia, Queensland 4067 (AU))

1990-05-01

48

Ferric iron content of ferropericlase as a function of composition, oxygen fugacity, temperature and pressure: Implications for redox conditions during diamond formation in the lower mantle  

NASA Astrophysics Data System (ADS)

We investigated the ferric iron (Fe3+) concentration in (Mg,Fe)O ferropericlase using the flank method applied to Mg-Fe interdiffusion couples of ferropericlase. Diffusion couples with Mg/(Mg+Fe) in the range 0.44 to 1 were annealed at temperatures of 1673-1873 K and pressures of 5-24 GPa over a wide range of oxygen fugacities. Oxygen fugacity was controlled by Fe, Ni, Mo, and Re metal capsules and their corresponding oxide phases. Based on our results and available experimental data, we derived an equation for the Fe3+ solubility in ferropericlase applicable to depths at the top of the lower mantle: [Fe3+]=C (XFe4fO2)m exp{-((1-XFe)E*Mg+XFeE*Fe+PV*)/RT}, where C=2.6(1)×10-3, m=0.114(3), E*Mg=-35(3) [kJ/mol], E*Fe=-98(2) [kJ/mol], and V*=2.09(3) [cm3/mol]. The value of the oxygen fugacity exponent m implies that Fe3+ mostly occupies tetrahedral sites under these conditions, which is consistent with the results of previously reported Mössbauer spectroscopy studies. Based on this relationship, we calculated the redox conditions of ferropericlase inclusions in diamonds believed to have come from the lower mantle. The estimated oxygen fugacities are close to the upper stability limit of diamond in mantle peridotite at the top of the lower mantle at adiabatic or slightly superadiabatic temperatures, which suggests that ferropericlase inclusions recorded and preserved the conditions at which diamond was precipitated from carbonates or carbonatite melts near the top of the lower mantle.

Otsuka, Kazuhiko; Longo, Micaela; McCammon, Catherine A.; Karato, Shun-ichiro

2013-03-01

49

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

USGS Publications Warehouse

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.

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

1977-01-01

50

Oxygen fugacity calibration for (Fe)Au75Pd25 alloys in rock-melting experiments  

NASA Astrophysics Data System (ADS)

Iron loss from silicate melt to gold-palladium capsules is strongly dependent on oxygen fugacity and, once calibrated, may be used as a tool to determine the fO2 of rock-melting experiments, provided that Fe partitioning between the melt and capsule is independent of melt composition. We performed nine rock-melting experiments in a gas-mixing furnace at 1 atm on three compositions of mafic rock: a MORB (9.5 wt% FeOT) and two subduction-related Mexican basaltic andesites (7.5 wt% and 7.0 wt% FeOT). The samples were melted for 48 hours in Au75Pd25 capsules at 1300°C and three different oxygen fugacities spanning -1 to +2 log units relative to the nickel-nickel oxide buffer. Electron microprobe analyses for Fe in both the melt and capsule material yield Fe-partition coefficients that vary linearly with log fO2 and are essentially constant and independent of melt composition at any given fO2. This relationship permits making post-run estimates of the prevailing fO2 in rock-melting experiments at 1300°C from the partitioning of Fe between the melt and capsule for bulk compositions within our calibrated limits. Work is now underway to extend this calibration to lower temperatures. Our plan is to use this calibration to estimate the fO2 in H2O-undersaturated piston-cylinder experiments in which fO2 cannot be buffered by conventional double capsule methods.

Weber, R. M.; Weaver, S.; Johnston, A.; Wallace, P. J.

2009-12-01

51

Compressibility and Fugacity of Gaseous Hydrogen.  

National Technical Information Service (NTIS)

The concept of fugacity is explained. Application of compressibility and fugacity data in hydrogen embrittlement calculations is discussed. Equations of state are reviewed. Compressibility factors and fugacity coefficients are calculated. A best estimate ...

H. P. Vanleeuwen

1983-01-01

52

Discrete water column measurements of CO 2 fugacity and pH T in seawater: A comparison of direct measurements and thermodynamic calculations  

Microsoft Academic Search

The NOAA Eq. Pac. CO2 system data set (?2500 water samples) has been evaluated to assess the internal consistency of measurements and calculations involving CO2 fugacity and pHT. This assessment represents the first large scale field comparison of pHT and fCO2 data. Comparisons of direct discrete CO2 fugacity (fCO2) measurements with CO2 fugacity calculated from total inorganic carbon (CT), total

S McElligott; R. H Byrne; K Lee; R Wanninkhof; F. J Millero; R. A Feely

1998-01-01

53

Oxygen self-diffusion in calcite: Dependence on temperature and water fugacity  

NASA Astrophysics Data System (ADS)

Oxygen self-diffusion in natural calcite single crystals was studied hydrothermally at 400-800°C and 10-350 MPa confining pressure. Diffusion coefficients ( D) were determined from 18O concentration profiles measured with an ion microprobe. At 100 MPa confining pressure, the Arrhenius parameters yield an activation energy ( Q) = 173 ± 6 kJ/mole and pre-exponential factor ( D0) = 7 × 10 -9 m 2/s over the temperature range 400-800°C, and there is no measurable anisotropy. Constant temperature experiments at 700°C indicate that there is a strong linear correlation (slope = 0.9) of D with water fugacity over the range 4-240 MPa, consistent with the interpretation that, in the presence of water, the dominant oxygen-bearing transport species in calcite is molecular water. A sample containing 1180 ppm Mn shows a marked increase in observed D values at temperatures below ˜ 600°C. However, when pre-annealed at ? 700°C the D values obtained at 550°C are within a factor of four of the value obtained for the low (100 ppm) Mn sample. The results of this study confirm that in contrast to carbon, oxygen diffusion rates in calcite are greatly enhanced when water is present. The difference in the effect of water on Doxygen and Dcarbon in calcite may provide valuable information for evaluating the role of fluids in the thermal histories of calcite-bearing rocks.

Farver, John R.

1994-02-01

54

The influence of oxygen fugacity on melt evolution: 1 atmosphere experiments on Aleutian basaltic andesites  

NASA Astrophysics Data System (ADS)

Magmatic differentiation trends can be approximated geochemically by liquid lines of descent, which can be modeled using high pressure and temperature experiments. Prior experimental studies indicate that oxygen fugacity (fO2) influences the compositional evolution of the melt phase during equilibrium crystallization, with more oxidized systems producing melts along a calc-alkaline differentiation trend, while more reduced systems produced tholeiitic melts. This study focuses on the influence of oxygen fugacity on equilibrium crystallization in natural basaltic andesites from Westdahl and Okmok volcanoes, Aleutians, Alaska. We conducted a series of experiments at 1 atmosphere with fO2 approximating the Ni-NiO (NNO) and Quartz-Fayalite-Magnetite (QFM) buffers, using H2-CO2 gas mixtures, at temperatures between 1053 and 1262 °C. We employed Fe-plated Pt wire loops as sample containers to minimize experiment Fe-loss. Melting experiments run above 1150 °C were texturally glassy with generally sparse, well-formed phenocrysts. Experiments that were aimed at crystallization at much lower temperatures (1100 °C or lower), required a controlled cooling-rate approach, and the experiments were first equilibrated for 24 hours at 1180 °C, and then temperature was ramped down at a rate of 0.8 °C per hour, resulting in well-crystallized run products. Basaltic andesite (52.4 wt. % SiO2) from the 1997 Okmok eruption run at fO2 ~NNO crystallized plagioclase, clinopyroxene, and Fe-Ti oxides at relatively high temperatures between 1200 and 1250 °C, with olivine forming at temperatures below 1200 °C. At NNO, the 1992 Westdahl basaltic andesite (54.2 wt. % SiO2) starting material produced plagioclase and Fe-Ti oxides between 1200 and 1250 °C, with clinopyroxene forming below about 1180 °C. Olivine did not form in the Westdahl starting composition in the NNO experiments. In both starting compositions run at fO2 ~ QFM, the experiments remained more melt-rich to lower temperatures. At QFM, the Okmok composition produced plagioclase on the liquidus at temperatures above 1200 °C, but Fe-bearing phases did not form until olivine appeared at 1150 °C, followed by clinopyroxene at ~1125 °C. At QFM, the Westdahl basaltic andesite produced only glass and plagioclase to temperatures as low as 1113 °C, with olivine, clinopyroxene, and Fe-Ti oxides crystallizing between 1053 and 1113 °C. Our preliminary results agree with those of prior experimental studies, which predict that higher oxygen fugacities enhance the early crystallization of Fe-Ti oxides, pyroxenes, and olivine, thus influencing the liquid line of descent towards early Fe-depletion and a higher degree of melt compositional evolution. Our experiments demonstrate that at NNO, both Westdahl and Okmok starting materials produced early crystallization of all Fe-bearing phases, while at QFM, the system remained more melt-rich, with plagioclase dominating at higher temperatures, and mafic phases crystallizing only at temperatures below about 1150 to 1100 °C.

Larsen, J. F.; Rader, E. L.

2010-12-01

55

Oxidation state of vanadium in glass and olivine from terrestrial and Martian basalts: Implications for oxygen fugacity estimates  

SciTech Connect

Several studies have demonstrated the usefulness of synchrotron micro x-ray absorption near-edge structure ({mu}-XANES or SmX) spectroscopy in determining the oxidation state of elements in planetary materials. Delaney et al. used SmX to investigate the oxidation states of Fe, Cr, and V in extraterrestrial samples, and they later determined the oxidation state of V in experimental glasses as a function of oxygen fugacity. More recently, Sutton et al. studied the oxidation state of V in meteoritic fassaite and also in synthetic pyroxene. This report discusses our first results using SmX spectroscopy to determine the oxidation state of V in olivine and glass from a terrestrial ocean floor (OF) basalt and a martian basaltic shergottite meteorite, Dar Al Gani 476. The goal of this and future studies is to use V (and Cr, Fe) valence states to determine the oxygen fugacity of basalts from different planetary bodies.

Karner, J.M.; Sutton, S.R.; Papike, J.J.; Shearer, C.K.; Newville, M. (Univ New Mexico); (UC)

2005-04-22

56

Experimental determination of Ni diffusion coefficients in olivine and their dependence on temperature, composition, oxygen fugacity, and crystallographic orientation  

Microsoft Academic Search

Diffusion couple experiments were carried out with San Carlos olivine (Fo90) and NiFe alloys (Ni100, Ni97Fe3, Ni90Fe10) or other olivine compositions (Fo100, Fo25) in order to determine the dependence on temperature, oxygen fugacity, composition and crystallographic orientation of Ni diffusion coefficient (DNi) in olivine. Experiments at 1 atmosphere total pressure cover a temperature range of 900–1445°C with run durations from

Christof Petry; Sumit Chakraborty; Herbert Palme

2004-01-01

57

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

Microsoft Academic Search

A refined set of Mössbauer parameters (isomer shifts, quadrupole splittings, Fe2+\\/Fe3+ ratios) and lattice parameters were obtained from annites synthesized hydrothermally at pressures between 3 and 5 kbars, temperatures ranging from 250 to 780° C and oxygen fugacities controlled by solid state buffers (NNO, QMF, IM, IQF). Mössbauer spectra showed Fe2+ and Fe3+ on both the M1 and the M2

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

1993-01-01

58

The effect of oxygen fugacity on hydroxyl concentrations and speciation in olivine: Implications for water solubility in the upper mantle  

Microsoft Academic Search

The effect of oxygen fugacity on hydroxyl speciation and solubility in San Carlos olivine was investigated in a series of piston cylinder experiments at 2.0 GPa and 1100 and 1300 °C. The presence of enstatite was intended to fix silica activity and experimental fO2 in most runs was regulated by lining the inner walls of the sample-containing Pt capsules with either Fe,

K. J. Grant; R. A. Brooker; S. C. Kohn; B. J. Wood

2007-01-01

59

The effect of oxygen fugacity on hydroxyl concentrations and speciation in olivine: Implications for water solubility in the upper mantle  

Microsoft Academic Search

The effect of oxygen fugacity on hydroxyl speciation and solubility in San Carlos olivine was investigated in a series of piston cylinder experiments at 2.0 GPa and 1100 and 1300 °C. The presence of enstatite was intended to fix silica activity and experimental fO2 in most runs was regulated by lining the inner walls of the sample-containing Pt capsules with

K. J. Grant; R. A. Brooker; S. C. Kohn; B. J. Wood

2007-01-01

60

Partitioning of Fe 3+\\/Fe total between amphibole and basanitic melt as a function of oxygen fugacity  

Microsoft Academic Search

We present the first microbeam measurements of Fe3+\\/Fetotal and H contents in amphiboles and glasses synthesized from a basanite at high temperature and pressure where oxygen fugacity (fO2) was buffered and water activity was monitored. The amphiboles were synthesized from basanite (San Carlos, AZ, USA) at 1100–1175°C and 1.5–2.0 GPa, at four fO2 values from the iron–wüstite (IW) buffer to

P. L. King; R. L. Hervig; J. R. Holloway; J. S. Delaney; M. D. Dyar

2000-01-01

61

Oxygen fugacity regime in the upper mantle as a reflection of the chemical differentiation of planetary materials  

Microsoft Academic Search

Oxygen fugacity (fO2) in the Earth’s mantle has a bearing on the problems of the chemical differentiation of the Earth’s materials and formation\\u000a of the chemical and phase state of its shells. This paper addresses some problems concerning changes in the redox state of\\u000a the upper mantle over geologic time and through its depth and the possible influence of fO2

A. A. Kadik

2006-01-01

62

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

Microsoft Academic Search

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)

Yves Thibault; John R. Holloway

1994-01-01

63

The relative effects of pressure, temperature and oxygen fugacity on the solubility of sulfide in mafic magmas  

Microsoft Academic Search

The sulfur contents at sulfide saturation (SCSS) of a basaltic and a picritic melt have been measured experimentally as a function of pressure and temperature from 5 to 90 kb and 1400–1800°C, using piston-cylinder and multi-anvil solid media pressure devices. Three distinct regimes of oxygen fugacity were investigated, imposed by the use of Fe100, Fe40Ir60, and Fe20Ir80 capsules. The compositions

JOHN A. MAVROGENES; Hugh St. C O’Neill

1999-01-01

64

Oxygen fugacity and geochemical variations in the martian basalts: implications for martian basalt petrogenesis and the oxidation state of the upper mantle of Mars  

Microsoft Academic Search

The oxygen fugacity of the Dar al Gani 476 martian basalt is determined to be quartz-fayalite-magnetite (QFM) ?2.3 ± 0.4 through analysis of olivine, low-Ca pyroxene, and Cr-spinel and is in good agreement with revised results from Fe-Ti oxides that yield QFM ?2.5 ± 0.7. This estimate falls within the range of oxygen fugacity for the other martian basalts, QFM

Christopher D. K Herd; Lars E Borg; John H Jones; James J Papike

2002-01-01

65

Solubility of copper in silicate melts as function of oxygen and sulfur fugacities, temperature, and silicate composition  

NASA Astrophysics Data System (ADS)

The solubility of Cu in silicate melts coexisting with liquid Cu(Fe) metal and liquid Cu(Fe) sulfide was determined experimentally at oxygen fugacities ranging from 10 -9.1 to 10 -13.6 bar and sulfur fugacities ranging from 10 -2.5 to 10 -6.3 bar at 1300°C. An iron oxide-free silicate of anorthite-diopside eutectic composition and a synthetic MgO-rich basaltic silicate (FeO-bearing) were used in the partitioning experiments. In S-containing systems, some of the metal reacted to metal sulfide. The silicates in the four systems investigated (Fe-free and S-free; Fe-containing and S-free; Fe-free and S-containing; Fe-containing and S-containing) had different colors depending on the dissolved Cu species and the presence of iron and/or sulfur. Irrespective of the presence of sulfur, the solubility of Cu in the silicate increases with increasing oxygen fugacity and metal/silicate partition coefficients for Cu decrease. Increasing the temperature from 1300°C to 1514°C increases the Cu solubility (decreases the metal/silicate partition coefficient) at an oxygen fugacity 0.5 log units below the iron-wüstite (IW) equilibrium in the Fe-free, S-free and Fe-containing, S-free systems. We infer the presence of monovalent Cu + ("CuO 0.5") in the silicate melt on the basis of the solubility of Cu as function of oxygen fugacity. Experiments containing iron yield a formal valence of ˜0.5 for Cu at very low oxygen fugacities, which is not observed in Fe-free systems. The low formal valence is explained by redox reactions between iron and copper in the silicate melts. There is no evidence for sulfidic dissolution of Cu in the silicates but sulfur has indirect effects on Cu partitioning. Iron metal/silicate partition coefficients depend on oxygen fugacity and on sulfur fugacity. Sulfidic dissolution of iron and oxide-sulfide exchange reactions with Cu cause a small increase in Cu metal/silicate partition coefficients. We derive an activity coefficient (? CuO 0.5) of 10 ± 1 for liquid CuO 0.5 at 1300°C for the silicate melts used here. A comparison with literature data shows that log ? CuO 0.5 increases in proportion to the mass percentages [CaO +(Al 2O 3)/2] in silicate melts. We recommend the following equations for Cu metal/silicate and sulfide/silicate partitioning for geochemical and cosmochemical modeling if silicate composition and the activity of Cu in the metal or sulfide is known: log D met/sil = -0.48 - 0.25 · log fO 2 - log ? Cu metal + 0.02 · [CaO + (Al 2O 3)/2; wt%] silicate logD sul/sil=+0.76-0.25 · logfO 2+0.25logfS 2-log? CS 0.5,sulfide +0.02 · [CaO+Al 2O 3/2;wt%] silicate. The derived Cu metal/silicate and metal/sulfide partition coefficients are applied to core formation in the Earth and Mars. The observed Cu abundances in the Earth cannot be easily explained by simple core-mantle equilibrium, but the observed Cu abundances for Mars are consistent with core-mantle equilibrium at low pressure and temperatures.

Holzheid, A.; Lodders, K.

2001-06-01

66

Self diffusion of europium, neodymium, thorium, and uranium in haplobasaltic melt: The effect of oxygen fugacity and the relationship to melt structure  

SciTech Connect

We report new measurements of self diffusion coefficients (D) for Mg, Nd, Eu, Th, and U in a haplobasaltic (Fo{sub 15}Di{sub 40}An{sub 45}) melt at 1 atm. 1400-1500{degrees}C, and oxygen fugacities corresponding to air and the Fe-FeO buffer. Diffusion couples consisted of isotopically distinct melts of the same chemical composition. and isotopic concentration profiles in quenched couples were measured with an ion probe. The valence state distributions of Eu and U were determined from absorption spectroscopy and model calculations, which demonstrate a shift from Eu{sup 3+} and U{sup 5.5+} in air to Eu{sup 2.5+} and U{sup 4+} at Fe-FeO. D{sub Mg}, D{sub Nd}, and Dn are independent of oxygen fugacity and agree well with our previous measurements. D{sub Eu} = D{sub Nd} in air and increases by 42% at Fe-FeO, while D{sub u} = D{sub Th} in air and shows a possible small increase of {approximately}20% at Fe-FeO. The change in D{sub Eu} with oxygen fugacity matches the established ionic radius and charge dependence for Mg, Ca, Ba, Nd,Yb, Ti, and Zr, while diffusion coefficients for Zr, Th, U{sup 4+}, and U{sup 5.5+} are independent of ionic radius and charge. Activation energies for all cations are approximately equal, independent of oxygen fugacity, and approximately match the activation energy for viscous flow. In addition, activation energies and diffusion coefficients recently measured for O and Si in basalt agree well with the present values. The good agreement between the various activation energies and between network modifier and network former diffusivities is consistent with a model in which diffusion of network modifying cations in low viscosity melts is controlled largely by the extrinsic influence of the melt network reorganization, with an additional influence from the intrinsic mobilities of the individual cations. 37 refs., 7 figs., 5 tabs.

LaTourrette, T.; Wasserburg, G.J. [California Institute of Technology, Pasadena, CA (United States)

1997-02-01

67

The effect of hydrogen, oxygen, and water fugacity on oxygen diffusion in alkali feldspar  

Microsoft Academic Search

Oxygen self-diffusion in adularia and albite single crystals was studied hydrothermally at 650°C from 5 to 1,500 MPa confining pressure using a combination of hydrogen\\/oxygen buffers, a hydrogen ion buffer, and variable mole fractions of water (dilution with COâ). Diffusion coefficients (D) were determined from ¹⁸O concentration profiles measured with an ion microprobe. There is a good correlation of the

J. R. Farver; R. A. Yund

1990-01-01

68

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

NASA Astrophysics Data System (ADS)

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).

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

2010-05-01

69

Fugacity Examples  

ERIC Educational Resources Information Center

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

David, Carl W.

2004-01-01

70

Correction of Holloway's (1977) adaptation of the modified Redlich-Kwong equation of state for calculation of the fugacities of molecular species in supercritical fluids of geologic interest  

Microsoft Academic Search

Consideration of constraints imposed on fugacity coefficients by the Gibbs-Duhem equation and those inherent in the Redlich-Kwong equation of state (Redlich and Kwong, 1949) and its modification by de Santis et al. (1974) indicates that Holloway's (1977) adaptation of the Redlich-Kwong equation for calculating fugacity coefficients of molecular species in gas mixtures is in error. Revised calculations using the correct

George C. Flowers

1979-01-01

71

High pressure effects on the iron?iron oxide and nickel?nickel oxide oxygen fugacity buffers  

SciTech Connect

The chemical potential of oxygen in natural and experimental samples is commonly reported relative to a specific oxygen fugacity (fO{sub 2}) buffer. These buffers are precisely known at 1 bar, but under high pressures corresponding to the conditions of the deep Earth, oxygen fugacity buffers are poorly calibrated. Reference (1 bar) fO{sub 2} buffers can be integrated to high pressure conditions by integrating the difference in volume between the solid phases, provided that their equations of state are known. In this work, the equations of state and volume difference between the metal-oxide pairs Fe-FeO and Ni-NiO were measured using synchrotron X-ray diffraction in a multi-anvil press and laser heated diamond anvil cells. The results were used to construct high pressure fO{sub 2} buffer curves for these systems. The difference between the Fe-FeO and Ni-NiO buffers is observed to decrease significantly, by several log units, over 80 GPa. The results can be used to improve interpretation of high pressure experiments, specifically Fe-Ni exchange between metallic and oxide phases.

Campbell, Andrew J.; Danielson, Lisa; Righter, Kevin; Seagle, Christopher T.; Wang, Yanbin; Prakapenka, Vitali B.; (NASA-JSC); (Maryland); (UC)

2009-09-25

72

Amphibole stability in primitive arc magmas: effects of temperature, H2O content, and oxygen fugacity  

NASA Astrophysics Data System (ADS)

The water-saturated phase relations have been determined for a primitive magnesian andesite (57 wt% SiO2, 9 wt% MgO) from the Mt. Shasta, CA region over the pressure range 200-800 MPa, temperature range of 915-1,070 °C, and oxygen fugacities varying from the nickel-nickel oxide (NNO) buffer to three log units above NNO (NNO+3). The phase diagram of a primitive basaltic andesite (52 wt% SiO2, 10.5 wt% MgO) also from the Mt. Shasta region (Grove et al. in Contrib Miner Petrol 145:515-533; 2003) has been supplemented with additional experimental data at 500 MPa. Hydrous phase relations for these compositions allow a comparison of the dramatic effects of dissolved H2O on the crystallization sequence. Liquidus mineral phase stability and appearance temperatures vary sensitively in response to variation in pressure and H2O content, and this information is used to calibrate magmatic barometers-hygrometers for primitive arc magmas. H2O-saturated experiments on both compositions reveal the strong dependence of amphibole stability on the partial pressure of H2O. A narrow stability field is identified where olivine and amphibole are coexisting phases in the primitive andesite composition above 500 MPa and at least until 800 MPa, between 975-1,025 °C. With increasing H2O pressure ({P}_{{H}_2O}), the temperature difference between the liquidus and amphibole appearance decreases, causing a change in chemical composition of the first amphibole to crystallize. An empirical calibration is proposed for an amphibole first appearance barometer-hygrometer that uses Mg# of the amphibole and f_{{O}_2}: P_{{H}2O}(MPa)=[{Mg#/52.7}-0.014 * Updelta NNO]^{15.12} This barometer gives a minimum {P}_{{H}2O} recorded by the first appearance of amphibole in primitive arc basaltic andesite and andesite. We apply this barometer to amphibole antecrysts erupted in mixed andesite and dacite lavas from the Mt. Shasta, CA stratocone. Both high H2O pressures (500-900 MPa) and high pre-eruptive magmatic H2O contents (10-14 wt% H2O) are indicated for the primitive end members of magma mixing that are preserved in the Shasta lavas. We also use these new experimental data to explore and evaluate the empirical hornblende barometer of Larocque and Canil (2010).

Krawczynski, Michael J.; Grove, Timothy L.; Behrens, Harald

2012-08-01

73

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

SciTech Connect

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}.

E Cottrell; K Kelley

2011-12-31

74

Post-entrapment modification of volatiles and oxygen fugacity in olivine-hosted melt inclusions  

NASA Astrophysics Data System (ADS)

The solubilities of volatiles (H2O, CO2, S, F, and Cl) in basaltic melts are dependent on variables such as temperature, pressure, melt composition, and redox state. Accordingly, volatile concentrations can change dramatically during the various stages of a magma's existence: from generation, to ascent through the mantle and crust, to final eruption at the Earth's surface. Olivine-hosted melt inclusions have the potential to preserve volatile concentrations at the time of entrapment due to the protection afforded by the host olivine against decompression and changes to the oxidation state of the external magma. Recent studies, however, have demonstrated that rapid diffusive re-equilibration of H2O and oxygen fugacity (f) can occur within olivine-hosted melt inclusions. Here we present volatile, hydrogen isotope, and major element data from dehydration experiments and a quantitative model that assesses proposed mechanisms for diffusive re-equilibration of H2O and f in olivine-hosted melt inclusions. Our comprehensive set of data for the behavior of common magmatic volatiles (H2O, CO2, F, Cl, and S) demonstrates that post-entrapment modification of CO2, and to a lesser extent S, can also occur. We show that the CO2 and S concentrations within an included melt decrease with progressive diffusive H2O loss, and propose that this occurs due to dehydration-induced changes to the internal pressure of the inclusion. Therefore, deriving accurate estimates for pre-eruptive CO2 and S concentrations from olivine-hosted melt inclusions requires accounting for the amount of CO2 and S hosted in vapor bubbles. We find, however, that Cl and F concentrations in olivine-hosted melt inclusions are not affected by diffusive re-equilibration through the host olivine nor by dehydration-induced pressure changes within the melt inclusion. Our results indicate that measured H2O, CO2 and S concentrations and Fe3+/?Fe ratios of included melts are not necessarily representative of the melt at the time of entrapment and thus are not reliable proxies for upper mantle conditions.

Bucholz, Claire E.; Gaetani, Glenn A.; Behn, Mark D.; Shimizu, Nobumichi

2013-07-01

75

Oxygen fugacity for stoichiometric magnetite Fe{sub 3}O{sub 4}-hercinite FeAl{sub 2}O{sub 4} solid solutions  

SciTech Connect

The Frenkel defect model is applied to determine the oxygen fugacity that corresponds to the preparation of magnetite-hercinite solid solutions with an exact 4:3 oxygen:cation ratio. The result are presented in graphic form for T=1300 deg. C.

Owoc, D. [Faculty of Physics and Nuclear Techniques, Department of Solid State Physics, University of Science and Technology, Cracow (Poland); KozIowski, A. [Faculty of Physics and Nuclear Techniques, Department of Solid State Physics, University of Science and Technology, Cracow (Poland)]. E-mail: kozlow@uci.agh.edu.pl; Kakol, Z. [Faculty of Physics and Nuclear Techniques, Department of Solid State Physics, University of Science and Technology, Cracow (Poland); Krol, G. [Faculty of Physics and Nuclear Techniques, Department of Solid State Physics, University of Science and Technology, Cracow (Poland); Honig, J.M. [Department of Chemistry, Purdue University, 1393 Brown Building, West Lafayette, IN 47907-1393 (United States)

2005-05-15

76

Phase Relations of Peridotite at 21-24 GPa and Variable Oxygen Fugacity: Implications for the 660 km Discontinuity  

NASA Astrophysics Data System (ADS)

Experiments to determine the liquidus to solidus phase relations were performed on different peridotite model compositions: a pyrolite doped with trace elements, an undoped KLB-1 composition, and a primitive mantle composition (PM-1) made from a 9:1 mixture of natural lherzolite and andesite. The pyrolite and KLB-1 compositions, prepared as oxide mixes, were contained in Re-capsules, whereas the PM-1 composition was contained in C-capsules. The experiments were carried out using multianvil presses with 10/4 mm and 18/8 mm octahedral pressure cell configurations with cylindrical LaCrO3 heaters and axial W-Re thermocouples. Massive Re-containers with double sample holes allowed two compositions to be run simultaneously at identical conditions in some of the experiments. Both the thermal gradient and the oxygen fugacity are lower in the thick-walled diamond capsules relative to the Re-capsules. Within experimental uncertainties, the phase relations of the KLB-1 and pyrolite compositions in Re-capsules are identical in the 21-24 GPa range. The crystallization sequence is garnet-ferropericlase-Ca-perovskite (ga-fp-cpv) at 21 GPa, ga-fp-perovskite (pv)-cpv at 22 GPa, and fp-pv-ga-cpv at 23-24 GPa. The solidus is approximately coincident with the appearance of cpv. Ringwoodite is replaced by ga at near-solidus conditions at 21-22 GPa. The near-liquidus and near-solidus fp have Mg/(Mg+Fe) ratios of about 0.92 and 0.85, respectively, with compositions largely independent of pressure in the 21-24 GPa range. Whereas the majoritic ga formulas have cation sums of 8.00, assuming 12 oxygen atoms and no ferric Fe, the pv formulas have cation sums exceeding 8.00, possibly resulting from the presence of ferric iron. Mössbauer spectroscopy of a 23 GPa run product gives Fe3+/total Fe ratios of 0.19 in the quenched melt and 0.28 in the bulk solid assemblage, indicating that the perovskites are dominated by ferric iron. Addition of 1% metallic iron to the starting material in a 23 GPa experiment changed the crystallization sequence from fp-pv-ga to fp-ga-pv, indicating a relative destabilization of perovskite at reduced oxygen fugacity. Experiments on the PM-1 composition in C-capsules resulted in the crystallization sequence ga-fp-pv and fp-ga-pv at about 23 and 24 GPa, respectively. The relative stabilization of ga at the expense of pv in C-capsule experiments on PM-1 may be partly related to the slightly higher contents of Si, Al, and Ca in the PM-1 starting material. Based on the identical phase relations of the pyrolite and KLB-1 compositions and the overall similarity between the pyrolite and PM-1 compositions, the destabilization of pv is mainly due to the lower oxygen fugacity imposed by the C-capsule. The depth to the 660 km discontinuity may vary laterally as a function of the oxygen fugacity, with relatively oxidized regions resulting in a shallowing of the discontinuity. This effect may reduce the depression of the discontinuity in areas of cold subducted slabs. The replacement of ringwoodite by ga at high subsolidus temperatures implies that the high-T pv-forming reaction has positive dp/dT-slope, and hot plumes may consequently accelerate through the boundary. Such an acceleration would be enhanced or reduced, depending on whether the plume has lower or higher oxygen fugacity than the ambient mantle.

Tronnes, R. G.; Frost, D. J.; Walter, M. J.; McCammon, C.; Nakamura, E.

2001-12-01

77

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

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

B. J. Hensen

1986-01-01

78

Importance of oxygen fugacity for temperatures and melting regimes beneath ridges, arcs, and hot spots  

NASA Astrophysics Data System (ADS)

Oxygen fugacity (fO2) plays a central role in controlling phase equilibria and the behavior of multi-valent elements (e.g., Fe, C). Primitive basalts are petrologic indicators of the conditions of mantle melting, and Fe is particularly important because its behavior and abundance in basalt are highly sensitive to P and T of mantle melting. Yet, Fe is also uniquely sensitive to the fO2 of the mantle source, which controls the relative abundances of the two major species of Fe in the upper mantle (Fe2+, Fe3+). Because Fe2+ is the more sensitive geothermometer, constraining Fe speciation in basalts is key to accurately interpreting Fe as a sensor of magmatic and mantle conditions. Here, we present new constraints on the Fe3+/?Fe ratios (i.e., Fe3+/[Fe2++Fe3+]) of basalts from ridges, arcs, and hot spots, determined using ?-XANES analysis of glasses and melt inclusions, and assess how fO2 influences the use of basalt Fe content to interpret P-T conditions of magmas and melting. Using ol-liquid or ol-opx-liquid thermometry (Putirka, 2007; Lee et al., 2010), modeled basalt temperatures decrease by ~0.4-0.6°C, and equilibration temperatures of basalt with the mantle decrease by ~4.4°C, for every 1% increase in Fe3+/?Fe ratio of the melt. Global mid-ocean ridge basalts (MORB) have a narrow range of Fe3+/?Fe (0.13-0.17; Cottrell & Kelley, 2011), significantly higher than prior bulk analyses have shown (0.07-0.12; Christie et al., 1986; Bezos & Humler, 2005). This upward revision has a small impact on modeled magmatic temperatures (max. ?T of -4 to -6°C), but it significantly impacts the modeled temperature of the MORB mantle source (max. ?T of -44°C), shallowing the base of the melting triangle by ~15 km. This decrease in potential temperature may be overshadowed, however, by the impact of fO2 on the depth of the graphite-CO2 transition. Reduced C has low solubility in silicate melts, but oxidized C will act as a flux (Dasgupta and Hirschmann, 2006). The upward revision of the MORB source fO2 may therefore expand the melt triangle by expanding the field of carbonatitic silicate melts (Dasgupta & Hirschmann, 2010). At arcs, both high dissolved H2O contents and high Fe3+/?Fe ratios (0.18 to 0.30, globally) in basalts impact thermobarometric models used to constrain mantle source conditions. An arc basalt with 6 wt.% H2O and Fe3+/?Fe=0.30 is ~80°C cooler than the same basalt with 2 wt.% H2O and Fe3+/?Fe=0.20, although only ~5°C of this difference is attributed to Fe speciation. At conditions of the arc mantle source, higher H2O contents and Fe3+/?Fe ratios of basalts indicate ambient mantle temperatures ranging from MORB-like to ~100°C cooler than the MORB source. Despite lower temperatures, however, melting beneath arcs may occur at higher pressures due to the inverted geothermal gradient and H2O input flux in the lower half of the mantle wedge beneath arc volcanoes. For ocean island basalts (OIB), Fe3+/?Fe ratios vary from MORB-like to relatively oxidized (0.14-0.25). Although OIBs may have both elevated Fe3+/?Fe ratios and higher dissolved H2O relative to MORB, higher total Fe concentrations than average MORB offset the effects of H2O and Fe3+ on modeled mantle temperatures. Mantle temperature beneath Samoa is modeled at ~150°C in excess of the average MORB source.

Kelley, K. A.; Cottrell, E.

2011-12-01

79

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

National Technical Information Service (NTIS)

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 magn...

M. C. McCanta M. J. Rutherford

2003-01-01

80

An experimental study of trace element partitioning between zircon and melt as a function of oxygen fugacity  

NASA Astrophysics Data System (ADS)

The partitioning of P, Sc, Ti, Sr, Y, Nb, the rare earth elements (REE), Hf, Ta, Th and U between zircon and a synthetic andesitic melt was determined as a function of oxygen fugacity (fO2) over a range of fourteen log units, from QFM-8 to QFM+6 (where QFM is the quartz-fayalite-magnetite oxygen buffer) at ˜1300 °C and 1 atm, using SIMS and LA-ICP-MS. The partition coefficients of Ce and Eu were found to vary systematically with fO2, relative to those of the other REE, producing Ce and Eu anomalies similar to those that are characteristic of natural igneous zircon. These anomalies coexist at terrestrial fO2s and were used to quantify Eu3+/(Eu2+ + Eu3+) and Ce4+/(Ce3+ + Ce4+) in the melt. The partition coefficients of the redox invariant trivalent cations are in excellent agreement with lattice strain theory. The values of DREE are related to those determined for natural samples by the expected dependence on temperature. The incorporation of REE3+ in zircon was independent of the presence of P. DU/DTh was found to vary systematically with fO2 indicating the presence of U4+, U5+ and U6+ in the melt at terrestrial conditions. DTi was independent of fO2 despite an expectation of significant Ti3+ in the most reduced experiments.

Burnham, Antony D.; Berry, Andrew J.

2012-10-01

81

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  

Microsoft Academic Search

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

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

1993-01-01

82

Solubilities of nitrogen and noble gases in silicate melts under various oxygen fugacities: implications for the origin and degassing history of nitrogen and noble gases in the earth  

Microsoft Academic Search

Solubility experiments for nitrogen and noble gases (Ar and Ne) in silicate melts were conducted using two experimental configurations: one was conducted at 1 atmospheric pressure, T =1300°C and oxygen fugacity (fO2) of IW + 0.9 (i.e., 0.9 log units higher than the iron-wüstite buffer) and the other at high pressures (Ptotal ? 2 × 108 Pa), 1500°C and fO2

Akiko Miyazaki; Hajime Hiyagon; Naoji Sugiura; Kei Hirose; Eiichi Takahashi

2004-01-01

83

A short timescale for changing oxygen fugacity in the solar nebula revealed by high-resolution 26Al– 26Mg dating of CAI rims  

Microsoft Academic Search

Most rocky objects in the solar system, including the primitive chondrites and the terrestrial planets themselves, formed at oxygen fugacities (fO2) near that of the Iron–Wüstite (IW) fO2 buffer. Conversely, the most ancient rocky objects of the solar system, the calcium aluminum-rich inclusions (CAIs), formed at fO2 values 5 orders of magnitude lower than the IW buffer in an environment

Justin I. Simon; Edward D. Young; Sara S. Russell; Eric K. Tonui; Kathryn A. Dyl; Craig E. Manning

2005-01-01

84

Experimental investigation of large-ion-lithophile-element-, high-field-strength-element- and rare-earth-element-partitioning between calcic amphibole and basaltic melt: the effects of pressure and oxygen fugacity  

Microsoft Academic Search

The effects of pressure and oxygen fugacity (fO2) on trace element partitioning between pargasitic amphibole and alkali-basaltic melts have been determined at pressures from\\u000a 1.5 to 2.5?GPa and oxygen fugacities at 2 log units above and below the nickel–nickel oxide buffer. Amphibole crystallization\\u000a experiments were performed in a piston cylinder apparatus and partition coefficients between amphibole and quenched melt of

Claude Dalpé; Don R. Baker

2000-01-01

85

Effects of Oxygen Fugacity and Temperature on Partitioning of Ni and Co Between Liquid Metal, Magnesium Silicate Perovskite and Magnesiowustite  

NASA Astrophysics Data System (ADS)

In the core formation stage, a magma ocean might have extended to the lower mantle depth, and Ni and Co might have been distributed throughout the magma ocean, solid lower mantle, and the Earth's core. Although it is important to determine effects of oxygen fugacity (fO2) and temperature on partition behavior of these elements between liquid iron and lower mantle minerals, it has not been well constrained because of its experimental difficulty. Partitioning of Ni and Co between liquid iron-rich metal and lower mantle minerals, such as magnesium silicate perovskite and magnesiowustite, was investigated at 26-27 GPa, 2680-3020 K and 1.15- 1.86 log units below the iron-wustite fO2 buffer. The experiments have been achieved at such conditions using a Kawai-type apparatus and a cell assembly optimized for high-temperature generation. Our experiments revealed that partition coefficients of Ni and Co between liquid iron-rich metal and the lower mantle minerals decrease with increasing fO2, whereas they have very week temperature dependence in the present temperature range. The present result makes it possible to evaluate Ni and Co abundance throughout the mantle for a plausible fO2 and temperature. The mantle abundance of Ni and Co may be explained by the core formation in the deep magma ocean with a bottom pressure of around 65 GPa (corresponding to 1500 km depth).

Kawazoe, T.; Ohtani, E.

2007-12-01

86

Ferric iron in orogenic lherzolite massifs and controls of oxygen fugacity in the upper mantle  

NASA Astrophysics Data System (ADS)

The bulk Fe2O3 contents and inter-mineral distributions of Fe3+ were investigated in a suite of samples from several orogenic lherzolite massifs, including Beni Bousera (Morocco), Ronda (Spain) and Lherz (France). Ferric iron contents were determined for each phase by Mössbauer spectroscopy and these results were combined with microprobe data and modal abundances to determine the bulk Fe2O3 contents. The notion that Fe3+ is moderately incompatible during partial melting in the mantle is supported by the observed decrease in bulk Fe2O3 content with increasing MgO, as well as by the generally lower Fe3+ content of clinopyroxene in samples with low modal abundances of this phase. The partitioning of Fe3+ between orthopyroxene and clinopyroxene is consistent with literature data for spinel peridotite xenoliths. The partitioning of Fe3+ between clinopyroxene and spinel is composition dependent, changing with the Cr/Al of spinel. Thus partitioning is expected to be different in the spinel peridotite and plagioclase peridotite facies of the upper mantle. The ƒO2 of orogenic massifs varies over several log units relative to the FMQ buffer. The values recorded by spinel-based and clinopyroxene-based oxygen barometry are generally comparable, indicating redox equilibrium between these two phases even at the relatively low temperature conditions existing in parts of the lithospheric mantle. Calculated bulk Fe2O3 contents range from 0.03 to 0.27 wt.%. The combination of modal abundance and major element composition means that orthopyroxene is a major contributor to the bulk Fe2O3 budget of peridotites, although clinopyroxene and spinel are much richer in Fe3+ on a per formula unit basis. Residual Cr-rich spinel is the dominant source of Fe3+ in plagioclase peridotites. In terms of the geochemical behaviour of Fe3+, it can be concluded that orogenic peridotites exhibit essentially the same behaviour as spinel peridotite xenoliths. In terms of the controlling factors of ƒO2 in the upper mantle, our data set records a certain degree of decoupling of ƒO2 from whole rock Fe2O3 content, even if a correlation between these two parameters is generally apparent. This decoupling is because, whereas both whole rock Fe2O3 content and ƒO2 are influenced by partial melting and melt extraction, additional processes such as metasomatism and phase changes can effectively reset ƒO2 without always causing a concomitant change in bulk Fe2O3 content. Modelling the oxidation of spinel reveals that the ƒO2 can be readily reset under initially reducing conditions, but the incorporation of progressively more and more Fe3+ in spinel is required to further raise ƒO2. A quasi-limit of ?logƒO2 = FMQ + 1 is expected. These results are consistent with the general redox behaviour observed for spinel peridotites. Our data imply that Fe3+ Fe2+ equilibria have an important, if not dominant influence on ƒO2 in the spinel peridotite facies of the upper mantle.

Woodland, A. B.; Kornprobst, J.; Tabit, A.

2006-06-01

87

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)

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.

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

2009-12-01

88

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)

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.

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

2010-05-01

89

An experimental study of H solubility in feldspars: Effect of composition, oxygen fugacity, temperature and pressure and implications for crustal processes  

NASA Astrophysics Data System (ADS)

A series of experiments, with run durations of ˜100-240 h, have been carried out on H solubility in natural labradorite, albite and anorthoclase at 2-10 kbar and 700-850 °C, in equilibrium with different oxygen buffer materials: Fe-FeO, Ni-NiO, Re-ReO2 and Fe2O3-Fe3O4. Attainment of equilibrium water contents were examined by conducting experiments with different run-durations and by performing profile analysis along crystal core-to-rim paths. The annealed products generally show typical OH-related infrared absorption bands in the range 3700-2600 cm-1: the spectra of the labradorite and anorthoclase are dominated by broad bands at ˜3300-3100 cm-1, while the spectra of the albite consist of broad bands at ˜3100-3000 cm-1 and sharp bands at ˜3600-3400 cm-1. The measured H solubility, ranging from ˜80 to 285 ppm H2O, differs greatly between the feldspars with different chemical compositions, depends strongly on oxygen fugacity, and increases with increasing temperature and pressure. The H solubility is significantly higher, e.g., by a factor of ˜3 or even more, at very reducing conditions than at oxidizing conditions. The high H solubility of feldspar at reduced conditions indicates that, at least locally, the Earth's ancient deep continental crust was probably more hydrous than the modern one. Crustal dehydration can be caused by a change of oxygen fugacity and a corresponding change of water solubility in the constituent feldspar under isothermal conditions, without the requirement of high temperature and/or additional heat sources.

Yang, Xiaozhi

2012-11-01

90

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

NASA Astrophysics Data System (ADS)

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).

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

2010-12-01

91

Oxygen fugacity of mare basalts and the lunar mantle application of a new microscale oxybarometer based on the valence state of vanadium  

SciTech Connect

Using the valence state of vanadium on a microscale in lunar volcanic glasses we have developed another approach to estimating the oxygen fugacity of mare basalts. 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 fO{sub 2}. Still, these approaches have been helpful and indicate that mare basalts crystallized at fO{sub 2} between the iron-wuestite 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 fO{sub 2} 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 fO{sub 2}, temperature, V coordination, and melt composition. Here, we report the initial results of this approach applied to lunar pyroclastic glasses.

Shearer, C.K.; Karner, J.; Papike, J.J.; Sutton, S.R. (UofC); (Univ. of New Mexico)

2004-05-25

92

The oxidation state of subcontinental mantle: oxygen thermobarometry of mantle xenoliths from central Asia  

Microsoft Academic Search

The oxygen fugacities of 48 mantle xenoliths from 5 localities in southern Siberia (USSR) and Mongolia have been determined. Ferric iron contents of spinels were measured by 57Fe Mössbauer spectroscopy and oxygen fugacities calculated from spinel-olivineorthopyroxene equilibrium. The samples studied represent the major types of upper mantle lithologies including spinel and garnet peridotites and pyroxenites, fertile and depleted peridotites and

D. A. Ionov; B. J. Wood

1992-01-01

93

The Oxygen Fugacity Structure of the Sub-Oceanic Lithosphere and Upper Mantle as Recorded by Spinel Peridotite and Garnet Clinopyroxenite Xenoliths from O'ahu, Hawai'i  

NASA Astrophysics Data System (ADS)

The oxygen fugacity (fO2) of the Earth’s mantle, as recorded by variations in Fe2+/Fe3+ in MORB glasses, spinel and garnet peridotites indicates it is heterogeneous with at least 5 log units variation with respect to the fayalite-magnetite-quartz(FMQ) buffer (+1.5 to -4.5 ?FMQ). This study employs the ferric iron contents of lherzolitic spinels and pyroxenitic garnet-clinopyroxene pairs measured by 57Fe Mössbauer spectroscopy and experimentally derived oxybarometers to quantify fO2 variations of the mantle beneath O’ahu. Samples analyzed are from the Pali, Salt Lake Crater and Kaau vents. Oxygen fugacity is calculated using the oxybarometers 6Fe2SiO4+O2=3Fe2Si2O6+2Fe3O4[1] and 2Fe3Fe2Si3O12=4Fe2SiO4+2FeSiO3+O2[2] for spinel and garnet assemblages respectively. Fe3+/?Fe of spinels range from 0.038-0.394 resulting in relatively oxidizing conditions, ?logfO2 of +0.3 to +1.0?FMQ with exception of one sample at -2.9?FMQ. These values are 1-2 log units more oxidized than the sub-ridge mantle, as sampled by abyssal peridotites(-0.9±0.7?FMQ) and MORBs(-0.4±0.4?FMQ). The O’ahu peridotites record similar degrees of depletion(Cr#sp=0.1-0.3) as abyssal peridotites, indicating a decoupling between fO2 and degree of depletion in the oceanic mantle. Elevated Na contents and LREE enrichments with convex upwards REE patterns also suggest that the O’ahu peridotites are not simple residues of MORB melting, but have been metasomatized subsequent to melting at the ridge by passing melts[3]. The presence of nano-diamonds in O’ahu pyroxenites, suggests these cumulates may have crystallized under more reducing conditions in the asthenosphere(~110-150 km)[4,5] and allow comparison between the fO2 of the shallower(TBKN1175-1350K) depleted lithospheric peridotites and deeper lithologies(TEG1260-1560K). Fe3+/?Fe of the pyroxenitic garnets range from 0.061-0.074 and their coexisting clinopyroxenes from 0.279-0.340. In the absence of orthopyroxene, oxygen fugacities are calculated assuming a pressure of 4.0 GPa resulting in ?logfO2 of -2.9 to -3.8?FMQ. Differences of 3 log units fO2 between the peridotites and pyroxenites sampled in O’ahu point to stratification of oxygen fugacity with depth in the oceanic upper mantle at least on the localized vent scale, reminiscent of observed trends in the South African craton[6]. The highly reduced nature of the O’ahu pyroxenites relative to both the overlying metasomatically overprinted, oxidized spinel peridotites and plume-derived lavas(-0.55±1?FMQ)[7] confirm observations from trace element and isotopic compositions that the pyroxenites are unrelated to the plume magmatism and just came along for the ride. [1]Bryndzia,L.T.&Wood,B.J.,Am.J.Sci.,290,1093-1116(1990) [2]Gudmundsson,G.&Wood,B.J.,C.M.P.,119,56-67(1995) [3]Bizimis,M.et al.,E.P.S.L.,217,43-58(2003) [4]Keshav,S.etal.,J.Pet.,48,1681-1724(2007) [5]Wirth,R.&Rocholl,A.,E.P.S.L.,211,357-369(2003) [6]McCammon,C.&Kopylova,M.G.,C.M.P.,148,55-68(2004) [7]Rhodes,J.M.&Vollinger,M.J.,C.M.P.,149,666-674(2005)

Tibbetts, N. J.; Bizimis, M.; Keshav, S.; Longo, M.; Salters, V. J.; McCammon, C. A.

2009-12-01

94

Laboratory study of vitrinite maturation rate as a function of temperature, time, starting material, aqueous fluid pressure, and oxygen fugacity — corroboration of prior work  

NASA Astrophysics Data System (ADS)

Kinetic investigations were performed on disaggregated samples of angiosperm and gymnosperm xylite (mainly pure huminite fragments) at 2.0 kbar aqueous fluid pressure and oxygen fugacities defined by hematite-magnetite and magnetite + quartz-fayalite buffers. Individual experiments lasted from 5 to 204 days. The rates of vitrinite reflectance (VR) increase were evaluated at 200, 250, 300, and 400 ^oC isotherms; experimentally determined, approximately steady-state values for the mean %R_r are 0.54, 0.74, 1.10, and 2.25, respectively. For geological lengths of time, appropriate values of %R_r = K_0t0.076 (where K_0 is a function of temperature, and t is in days). The overall activation energy describing the kinetics of devolatilization reactions responsible for increase in VR measured in our experiments is 21.8 ± 0.3 kJ/mol. Combined with earlier rate studies conducted by Dalla Torre et al. (1997) we conclude that the rate of vitrinite maturation is virtually unaffected by oxidation state, "wet" versus "dry" conditions, and nature of the starting lignitic material (conifers, hardwood). To a small extent, elevated lithostatic pressure retards the rate of increase in VR. Different, nonsystematic trends are observed for the resinite-exudatinite-bituminite present in the lignite material and in low temperature and short runs. Strong disequilibrium was recognized in short runs of the 200 and 250 ^oC isotherms. These new run data demonstrate that VR is chiefly a function of temperature and time. In support of earlier field, theoretical, and laboratory studies, for all but geologically insignificant time intervals, vitrinite reflectance is an appropriate proxy for host-rock burial temperature. Reference: Dalla Torre, M., Ferreiro Mählmann, R. and Ernst, W.G. (1997): Geochimica Cosmochimica Acta, 61/14, 2921-2928.

Ferreiro Mählmann, R.; Ernst, W. G.

2003-04-01

95

The Influence of PH and Oxygen Fugacity on the Hydrothermal Transport of Pb and Zn by Carboxylate Complexes.  

NASA Astrophysics Data System (ADS)

A chemical model was developed to evaluate the influence of log ? pH conditions on Pb and Zn complexation by acetate and malonate in 100oC basinal brines with bulk chemical compositions similar to diagenetic ore fluids and modern petroleum-field brines of moderate salinity (TDS = 180 g L-1). In the model composite brine, acetate with a concentration of 7,700 mg L-1 (0.13 m) represents the major monocarboxylate ligands detected in basinal brines, while malonate with a concentration of 300 mg L-1 (0.0029m) represents the dominant dicarboxylate ligands. Total Pb and Zn concentrations (constrained by galena and sphalerite solubility, respectively) and Pb and Zn speciation were calculated as a function of log and pH for the model composite fluid. The 1.0 and 10 ppm isopleths of total Pb and total Zn in carboxylate (acetate + malonate) complexes illustrate that the ore fluid of Giordano (1994) for red-bed related base metal deposits and Anderson?s (1975) Mississippi Valley-type ore fluid are potentially capable of transporting sufficient amounts of Pb and Zn in the form of carboxylate complexes to form economic deposits of Pb and Zn. Both of these fluids are oxidized, have very low total reduced sulfur, and have pHs in the range 5.5 to 6.5. On the other hand, the reduced ore fluid models of Sverjensky (1984) (projected to 100oC) and Giordano and Barnes (1981), both for Mississippi Valley ? type deposits, 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. The speciation results show that the log - pH conditions most favorable for carboxylate complexation are the same conditions under which chloride complexation dominates Pb and Zn speciation. Furthermore, the results show that basinal brines and related ore fluids characterized by temperatures near 100oC, high oxidation states (i.e., low total reduced sulfur), and high but reasonable concentrations of carboxylate anions can mobilize up to 3 percent of the total Pb and up to 1.3 percent of the total Zn as carboxylate complexes. These percentages, under the most favorable conditions, correspond to approximately 1 to 100 ppm of those metals in solution; concentrations that are adequate to form economic deposits of these metals. However, the field evidence from modern petroleum-field brines suggests that these optimal conditions, at 100oC, for carboxylate complexation are rarely met.

Giordano, T. H.

2001-12-01

96

Effect of high-temperature, high-oxygen-fugacity annealing on the stability of the (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10{+-}{delta}}-type compound  

SciTech Connect

The stability of the (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10{+-}{delta}}-type compound has been evaluated under conditions of elevated temperature (500--860 C) and elevated oxygen fugacity (i.e., in O{sub 2}/Ar gas mixtures containing {le}20% O{sub 2} at total pressures of {le}207 MPa). At sufficient high oxygen fugacities and temperatures, the (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10{+-}{delta}}-type compound transformed into a mixture of a strontium-rich (Bi, Pb){sub 1}(Sr,Ca,Cu){sub 2}O{sub y}-type compound, a calcium-rich (Bi,Pb){sub 1}-(Sr,Ca,Cu){sub 2}O{sub y}-type compound, CuO, and a small amount of (Sr,Ca)O. The decomposition of the (Bi,Pb){sub 2}Sr{sub 2}Ca-Cu{sub 3}O{sub 10{+-}{delta}}-type compound was accompanied by a 2%--3% weight gain, which was consistent with an oxidation reaction. The conditions of oxygen fugacity and temperature leading to decomposition, and the resulting decomposition products, are compared for the (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10{+-}{delta}}-type and Bi{sub 2}Sr{sub 2}Ca{sub 1}Cu{sub 2}O{sub 8{+-}{Psi}}-type compounds.

Allemeh, S.M.; Sandhage, K.H. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

1995-09-01

97

Activities and volumes in MgAl/sub 2/O/sub 4/ - Fe/sub 3/O/sub 4/ -. gamma. Fe/sub 8/3/O/sub 4/ spinels: implications for mantle oxygen fugacity  

SciTech Connect

The partial molar volumes of Fe/sub 3/O/sub 4/ and ..gamma..Fe/sub 8/3/O/sub 4/ components in synthetic spinels have been determined by x-ray powder diffraction with wet chemical analysis of Fe/sup 2 +//Fe/sup 3 +/. These data, in addition to published results for the join Fe/sub 3/O/sub 4/-..gamma..Fe/sub 8/3/O/sub 4/, characterize the partial molar volumes within the ternary spinel system. Both the Fe/sub 3/O/sub 4/-..gamma..Fe/sub 8/3/O/sub 4/ and MgAl/sub 2/O/sub 4/-..gamma..Fe/sub 8/3O/sub 4/ joins show nearly linear molar volumes of mixing. The MgAl/sub 2/O/sub 4/-Fe/sub 3/O/sub 4/ join, however, shows a significant positive deviation from ideality, with volumes given by: V(cm/sup 3//mole) = 44.58 X/sub mt/ + 43.65 X/sub ..gamma..hm/ + 39.79 X/sub sp/ + 0.26 X/sub mt/X/sub sp/ (1) The effect of pressure on published intrinsic oxygen fugacity measurements of spinel separates from upper mantle xenoliths may now be assessed. Applying the authors partial molar volume data to reaction (2) yields a ..delta..V of 0.408 cal/bar. This would correspond to an absolute increase in oxygen fugacity of 203 log units at 30kb and 1000/sup 0/C, or a relative increase of 1-2 log units in fO/sub 2/ when compared to a pressure corrected IW buffer. The oxygen fugacities of spinel-lherzolite xenoliths may also be estimated from Fe/sub 3/O/sub 4/ activities in spinel, which have been determined using a zirconia solid electrolyte. Applying the authors experimental activity data to coexisting olivine (X/sub fa/=0.10), orthopyroxene (X/sub fs/=0.10), spinel (X/sub mt/=0.01) assemblages and correcting to 30kb and 1000/sup 0/C yields a value for log fO/sub 2/ of -9.2 or 0.5 log units below the QFM buffer. These new data bring the previously disparate methods of estimating upper mantle oxygen fugacity into 1-2 log units better agreement of 30kb.

Mattioli, G.S.; Wood, B.J.

1985-01-01

98

Thermal state, oxygen fugacity and C?O?H fluid speciation in cratonic lithospheric mantle: New data on peridotite xenoliths from the Udachnaya kimberlite, Siberia  

NASA Astrophysics Data System (ADS)

Oxygen fugacity (fO2) and temperature variations in a complete lithospheric mantle section (70-220 km) of the central Siberian craton are estimated based on 42 peridotite xenoliths in the Udachnaya kimberlite. Pressure and temperature (P-T) estimates for the 70-140 km depth range closely follow the 40 mW/m2 model conductive geotherm but show a bimodal distribution at greater depths. A subset of coarse garnet peridotites at 145-180 km plots near the "cold" 35 mW/m2 geotherm whereas the majority of coarse and sheared rocks at ?145 km scatter between the 40 and 45 mW/m2 geotherms. This P-T profile may reflect a perturbation of an initially "cold" lithospheric mantle through a combination of (1) magmatic under-plating close to the crust-mantle boundary and (2) intrusion of melts/fluids in the lower lithosphere accompanied by shearing. fO2 values estimated from Fe3+/?Fe in spinel and/or garnet obtained by Mössbauer spectroscopy decrease from +1 to -4 ?log fO2 (FMQ) from the top to the bottom of the lithospheric mantle (˜0.25 log units per 10 km) due to pressure effects on Fe2+-Fe3+ equilibria in garnet. Garnet peridotites from Udachnaya appear to be more oxidized than those from the Kaapvaal craton but show fO2 distribution with depth similar to those in the Slave craton. Published fO2 estimates for Udachnaya xenoliths based on C-O-H fluid speciation in inclusions in minerals from gas chromatography are similar to our results at ?120 km, but are 1-2 orders of magnitude higher for the deeper mantle, possibly due to uncertainties of fO2 estimates based on experimental calibrations at ?3.5 GPa. Sheared peridotites containing garnets with u-shaped, sinusoidal and humped REE patterns are usually more oxidized than Yb, Lu-rich, melt-equilibrated garnets, which show a continuous decrease from heavy to light REE. This further indicates that mantle redox state may be related to sources and modes of metasomatism.

Goncharov, A. G.; Ionov, D. A.; Doucet, L. S.; Pokhilenko, L. N.

2012-12-01

99

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...

100

High pressure and high temperature fluid fugacities  

Microsoft Academic Search

Available high-temperature and high-pressure shock wave data on fluids are combined with low-temperature and low-pressure data to generate empirical equations of state in the virial format in reduced pressure and temperature for many species. A similar equation of state is derived for H2O. The fugacities of the pure species in the C-H-O system can be calculated using the present equation

S. K. Saxena; Y. Fei

1987-01-01

101

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

Microsoft Academic Search

We have constrained experimentally the effect of sulfur fugacity (fS2) and sulfide saturation on the fractionation and partitioning behavior of Pt, Pd and Au in a felsic silicate melt + sulfide crystal\\/melt + oxide + supercritical aqueous fluid phase + Pt + Pd + Au system. Experiments were performed at 800°C, 150 MPa, with oxygen fugacity (fO2) fixed at approximately

A. Bell; A. Simon

2009-01-01

102

High-resolution synchrotron X-ray powder diffraction and Rietveld structure refinement of two (Mg{sub 0.95},Fe{sub 0.5})SiO{sub 3} perovskite samples synthesized under different oxygen fugacity conditions  

SciTech Connect

This paper presents high-resolution synchrotron X-ray powder diffraction data at 290 K on two Fe-bearing, polycrystalline silicate perovskite samples with approximate compositions (Mg{sub 0.95}Fe{sub 0.05})SiO{sub 3} synthesized at 25 GPa and 1920 K in a multi-anvil press at different oxygen fugacity conditions. Rietveld structural refinements confirm that Fe{sup 2+} and Fe{sup 3+} dominantly substitute for Mg{sup 2+} in the 8-fold to 12-fold coordinated A site for both compositions. There appears to be no significant differences in the bond distances for these amounts of Fe{sup 3+} and no conclusive structural evidence to support indications from Moessbauer experiments that Fe{sup 3+} may occupy both A and B sites. To explore the effect of valence state further, this study also reports the first diffraction patterns of (Mg,Fe)SiO{sub 3} perovskite collected at a wavelength near the Fe absorption edge.

Jephcoat, A.P. [Univ. of Oxford (United Kingdom). Dept. of Earth Sciences; Hriljac, J.A. [Brookhaven National Lab., Long Island, NY (United States); McCammon, C.A.; O`Neill, H.St.C.; Rubie, D.C. [Univ. Bayreuth (Germany). Bayerisches Geoinstitut; Finger, L.W. [Carnegie Institution of Washington, DC (United States)

1999-03-01

103

Calculation of Decompression Schedules for Nitrogen-Oxygen and Helium-Oxygen Dives.  

National Technical Information Service (NTIS)

This report presents the theoretical basis for calculation of decompression schedules for nitrogen-oxygen and heliumoxygen mixtures used in diving. It includes definitions, theory of exponential saturation and desaturation, and theory of limiting values o...

R. D. Workman

1965-01-01

104

Photosynthesis and the dynamics of oxygen consumption in a microbial mat as calculated from transient oxygen microprofiles  

Microsoft Academic Search

A new method is presented to determine the rates of oxygen consumption, net oxygen metabolism (defined as photosynthesis minus oxygen consumption), and gross photosynthesis at high vertical resolution in benthic photo- trophic communities. The rates of oxygen consumption and of net oxygen metabolism as a function of depth and time are calculated from the dynamics in oxygen concentration, as measured

Eric H. G. Epping; Arzhang Khalili; Roland Thar

1999-01-01

105

Exact Inversion of the Fugacity-Density Relation for Ideal Quantum Gases  

Microsoft Academic Search

The fugacities of ideal Fermi and Bose gases are calculated explicity as a function of density and temperature, using the analytic properties of the integral appearing in the fugacity-density equation. The Hilbert problem of the theory of analytic functions is encountered.

A. Leonard

1968-01-01

106

Magnetite activities across the MgAl 2 O 4 Fe 3 O 4 spinel join, with application to thermobarometric estimates of upper mantle oxygen fugacity  

Microsoft Academic Search

The activity of Fe3O4 component in MgAl2O4-Fe3O4 spinels has been measured at 900° and 1000° C and 1 atm total pressure using a zirconia oxygen electrolyte. As previously reported for the dilute Fe3O4 concentration region (Mattioli and Wood 1986a), magnetite activity at 1000° C is greater than at 900° C at constant Fe3O4 mole fraction, for compositions across the MgAl2O4-Fe3O4

Glen S. Mattioli; Bernard J. Wood

1988-01-01

107

Calculation of oxygen isotope fractionation in hydroxyl-bearing silicates  

Microsoft Academic Search

The modified increment method has been applied to the calculation of oxygen isotope fractionation factors for hydroxl-bearing silicate minerals. The order of O-18 enrichment obtained in common rock-forming minerals is: pyrophyllite greater than kaolinite greater than tourmaline greater than or equal to tacl greater than prehnite greater than or equal to topaz greater than illite greater than phengite greater than

Yong-Fei Zheng

1993-01-01

108

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

USGS Publications Warehouse

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.

Hass, Jr. , J. L.

1970-01-01

109

Fugacity coefficients of H 2 , CO 2 , CH 4 , H 2 O and of H 2 O- CO 2 CH 4 mixtures: A virial equation treatment for moderate pressures and temperatures applicable to calculations of hydrothermal boiling  

Microsoft Academic Search

Equations derived from a quadratic virial equation in pressure, with virial coefficients expressed as a function of temperature, are fitted to published P - V - T and solubility data to yield values of second and third virial coefficients for pure and mixed gases. These coefficients are not virial coefficients sensu stricto and are used to compute fugacity coefficients of

Nicolas F. Spycher; Mark H. Reed

1988-01-01

110

A New Technique for Measuring the Effects of Oxygen Activity on Surface Energies: Application to Nickel.  

National Technical Information Service (NTIS)

A new technique for oxygen fugacity control was used in conjunction with the microcreep method for determination of surface energy. Oxygen fugacity was controlled by electrostatically controlled pumping through a solid zirconia electrolyte. The method was...

D. R. Stickle J. P. Hirth G. Meyrick R. Speiser

1975-01-01

111

Oxygen Transfer Calculations for a Tractor-Powered Paddlewheel Aerator.  

National Technical Information Service (NTIS)

Standardized aeration tests were conducted for a tractor-powered paddlewheel aerator of the type often used for emergency aeration of fish ponds. The greatest oxygen transfer coefficient (30.0/hour) and oxygen transfer rate (35.1 kg of oxygen per hour) we...

M. S. Armstrong C. E. Boyd

1982-01-01

112

Ocean Surface Carbon Dioxide Fugacity from Space  

NASA Astrophysics Data System (ADS)

We have developed a methodology to estimate ocean surface carbon dioxide (CO2) fugacity (partial pressure) using a combination for spacebased parameters, sea surface temperature (AMSR-E), dynamic topography (JASON and OSTM), productivity (MODIS), and salinity (possibly Aquarius) over global oceans. The ocean as the source and sink of CO2 is governed by the ocean-atmosphere exchange of this greenhouse gas. The exchange depends on the difference in fugacity (partial pressure) of carbon dioxide between sea and air, and a transfer velocity. Fugacity in sea is measured largely on ships; they are not sufficient to characterize spatial and temporal variability. Attempts have been made in the past to relate the fugacity in sea to parameters that could be measured from space. These relations are found to be valid only in limited regions and in specific seasons. We have developed a statistical model to estimate the fugacity over global ocean for all seasons from NASA space measurements using the state-of-art statistical techniques. We have produced the fugacity data over global ocean using salinity climatology but will replace the climatology with Aquarius data when they become available. We are evaluating the accuracy of the fugacity data and its application on carbon cycle and will explore proper remedies of any deficiency.

Xie, X.; Liu, W.

2011-12-01

113

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

NASA Astrophysics Data System (ADS)

A new method is developed to control water fugacity at a fixed pressure and temperature. We use two divariant phase assemblages (clinohumite-periclase-forsterite and brucite-periclase) in the MgO-SiO2-H2O system and the chemical reactions among co-existing phases buffer the water fugacity. In order to avoid a reaction between the water fugacity buffer and the specimen, a double-capsule assemblage was designed such that the water fugacity buffer was separated from the specimen by an inner metal jacket permeable to hydrogen and impermeable to other components. This method was applied to investigate the incorporation mechanisms of water in single crystals of San Carlos olivine as a function of water fugacity at 5 GPa and 1273 K. The chemical environment of the olivine crystal was controlled by the water fugacity buffer, the Ni-NiO oxygen fugacity buffer, and the olivine-orthopyroxene silica activity buffer. The establishment of chemical equilibrium was demonstrated by the presence of all relevant phases in the buffering reactions. The effect of water fugacity on water concentration in olivine was investigated using Fourier transform infrared (FTIR) spectroscopy with a polarized light. The total water concentration is nearly linearly dependent on water fugacity, indicating that the dominant incorporation mechanism of water in olivine involves two hydrogen atoms substituted in a Mg-site vacancy. The proposed method of the water fugacity buffer can be applicable to investigate the role of water in various important properties including water solubility and partitioning between mantle minerals, rheological properties, electrical conductivity, as well as solidus temperatures.

Otsuka, Kazuhiko; Karato, Shun-Ichiro

2011-11-01

114

The Remainder in Mayer's Fugacity Series  

Microsoft Academic Search

Upper and lower bounds are obtained for the remainder after a finite number of terms of the expansions in powers of fugacity z for the pressure p, the s-particle distribution functions, the density &rgr;, and the fugacity coefficient z?&rgr;, for a system of particles with two-body interactions. The interaction potential must be either nonnegative or else have a hard core

Oliver Penrose

1963-01-01

115

Fugacity coefficients for free radicals in dense fluids: HO{sub 2} in supercritical water  

SciTech Connect

Water at elevated temperatures and pressures in attracting interest as a reaction medium and an environmentally benign alternative to organic solvents. The fugacity coefficients of the hydroperoxyl radical in supercritical water are estimated through molecular simulations. A potential function for the radical is first derived from ab initio self-consistent field molecular orbital calculations at the unrestricted Hartree-Fock level and from data in the literature. Molecular dynamics simulations of the hydroperoxyl radical are then performed in supercritical water and the fugacity coefficient of the radical is calculated by the free-energy perturbation method using the dynamic coupling parameter window-modification technique. The values of the fugacity coefficients at 773 K differ from unity. This methodology facilitates the incorporation of thermodynamic nonidealities in mechanism-based kinetic models for free-radical reactions in supercritical water.

Mizan, T.I.; Savage, P.E.; Ziff, R.M. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering

1997-05-01

116

LASERS, ACTIVE MEDIA: Calculation of the mixing chamber of an ejector chemical oxygen --- iodine laser  

Microsoft Academic Search

Gas parameters are calculated at the outlet of the mixing chamber of an ejector chemical oxygen---iodine laser with a nozzle unit consisting of nozzles of three types, which provides a total pressure of the active medium that substantially exceeds a pressure in the generator of singlet oxygen. This technique of forming the laser active medium substantially facilitates the ejection of

M. V. Zagidullin; V. D. Nikolaev

2001-01-01

117

Calculation of the mixing chamber of an ejector chemical oxygen - iodine laser  

Microsoft Academic Search

Gas parameters are calculated at the outlet of the mixing chamber of an ejector chemical oxygen-iodine laser with a nozzle unit consisting of nozzles of three types, which provides a total pressure of the active medium that substantially exceeds a pressure in the generator of singlet oxygen. This technique of forming the laser active medium substantially facilitates the ejection of

M V Zagidullin; V D Nikolaev

2001-01-01

118

Calculations of Oscillation Spectra of Disordered Interstitial Solid Solutions of Vanadium-Oxygen System.  

National Technical Information Service (NTIS)

The frequency spectra calculation of disordered solid interstitial solutions of a vanadium-oxygen system for oxygen concentration of 5.9% and 15.8% (V sub 16 O and V sub 16 O sub 3 ) is carried out. The axially-symmetric model of crystal lattice dinamics ...

S. A. Danilkin

1978-01-01

119

Fixed-Fugacity Option for the EQ6 Geochemical Reaction Path Code.  

National Technical Information Service (NTIS)

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 ...

J. M. Delany T. J. Wolery

1984-01-01

120

The explicit expression of the fugacity for hard-sphere Bose and Fermi gases  

Microsoft Academic Search

In this paper, we calculate the explicit expression for the fugacity for three-dimensional hard-sphere Bose and Fermi gases from their equations of state in isochoric and isobaric processes, respectively, based on the mathematical result of the boundary problem of an analytic function -- the homogeneous Riemann-Hilbert problem.

Wu-Sheng Dai; Mi Xie

2009-01-01

121

Oxygen Diffusion in the Brain. Part 1: Spatial Conception and Calculation of Oxygen Diffusion.  

National Technical Information Service (NTIS)

A new model of oxygen diffusion in the brain is developed, based on anatomical investigations and theoretical considerations. In this cone model it is assumed that the diffusion path is determined by the difference between the pO sub 2 at a given point in...

K. Diemer

1972-01-01

122

The calculation of electron energy distributions and attachment coefficient for electron swarms in oxygen  

Microsoft Academic Search

Electron energy distributions have been calculated for electron swarms in oxygen for 15 less-than-or-eq, slant E\\/N less-than-or-eq, slant 152 Td. These distributions satisfy the experimentally measured values of both drift velocity and the diffusion coefficient, and allowed the theoretical value of the rate of attachment (?v) to be calculated to an accuracy of ±3%.The calculated values of ?\\/N are dependent

J Lucas; D A Price; J L Moruzzi

1973-01-01

123

Oxygen vacancies in N doped anatese TiO2: Experiment and first principles calculations  

SciTech Connect

We have determined the electronic and atomic structure of N doped TiO{sub 2} using a combination of hard x-ray photoelectron spectroscopy and first-principles density functional theory calculations. Our results reveal that N doping of TiO{sub 2} leads to the formation of oxygen vacancies and the combination of both N impurity and oxygen vacancies accounts for the observed visible light catalytic behavior of N doped TiO{sub 2}.

Rumaiz, A.; Woicik, J.C.; Cockayne, E.; Lin, H.Y.; Hassnain, J.; Shah, S.I.

2009-12-31

124

Oxygen vacancies in N doped anatase TiO2: Experiment and first-principles calculations  

NASA Astrophysics Data System (ADS)

We have determined the electronic and atomic structure of N doped TiO2 using a combination of hard x-ray photoelectron spectroscopy and first-principles density functional theory calculations. Our results reveal that N doping of TiO2 leads to the formation of oxygen vacancies and the combination of both N impurity and oxygen vacancies accounts for the observed visible light catalytic behavior of N doped TiO2.

Rumaiz, Abdul K.; Woicik, J. C.; Cockayne, E.; Lin, H. Y.; Jaffari, G. Hassnain; Shah, S. I.

2009-12-01

125

First principles calculations of oxygen vacancy passivation by fluorine in hafnium oxide  

NASA Astrophysics Data System (ADS)

The fluorine incorporation into HfO2 with oxygen vacancies has been investigated using first principles calculations. The authors show that atomic fluorine can efficiently passivate the neutral oxygen vacancy with excess energies of 4.98 and 4.39 eV for threefold- and fourfold-coordinated oxygen vacancy sites, respectively. The introduction of fluorine elevates the vacancy induced state into conduction band by transferring the neutral vacancy state to positively charged state, and thus removes the gap state which causes trap-assisted tunneling. The HfO2 band gap is not narrowed after fluorine incorporation.

Chen, Wei; Sun, Qing-Qing; Ding, Shi-Jin; Zhang, David Wei; Wang, Li-Kang

2006-10-01

126

Electronic properties of oxygen vacancy in HfO2 within GW calculations  

NASA Astrophysics Data System (ADS)

Hafnia (HfO2) has attracted much attention as a high-k dielectric material, which substitutes for silicon gate oxide in nanoscale metal-oxide-semiconductor (MOS) devices. However, there remain several problems to be resolved in hafnia-based devices, such as flat band shift and threshold voltage instability. Oxygen vacancy, as the most common intrinsic defect, is regarded as a major cause of these problems. As previous calculations mostly rely on the local-density-functional approximation (LDA), the defect levels of oxygen vacancy are not accurately determined because of the LDA band gap problem. Here we perform GW calculations for the defect levels of oxygen vacancy in monoclinic HfO2. Our calculations show that the Fermi level pinning of p+ poly Si gate electrode is due to the charge transfer from oxygen vacancy to the electrode. In addition, the charge trap of oxygen vacancy can lead to the threshold voltage instability in both nMOS and pMOS devices. Finally, we suggest that oxygen vacancy may be a cause of the gate leakage current by the Poole-Frenkel conduction.

Choi, Eun-Ae; Chang, Kee Joo

2009-03-01

127

First-principles calculation and experimental study of oxygen diffusion in uranium dioxide  

NASA Astrophysics Data System (ADS)

This work provides an illustration that density functional theory (DFT) + U calculations may quantitatively describe transport phenomena in uranium dioxide. Oxygen diffusion mechanisms are investigated using both ab initio calculations and experimental approaches mainly involving self-diffusion coefficient measurements. The dependences of the experimental data upon oxygen potential and sample impurity content demonstrate, by comparison with basic point defect and diffusion theory, that oxygen migration occurs via an interstitial mechanism. The temperature study provides an estimate of interstitial formation and migration energies which compare very favorably to energies calculated using the DFT+U approximation relating to the interstitialcy mechanism. Also, vacancy migration and Frenkel pair formation energies are shown to agree well with existing data.

Dorado, Boris; Garcia, Philippe; Carlot, Gaëlle; Davoisne, Carine; Fraczkiewicz, Mathieu; Pasquet, Bertrand; Freyss, Michel; Valot, Carole; Baldinozzi, Guido; Siméone, David; Bertolus, Marjorie

2011-01-01

128

The hard hexagon partition function for complex fugacity  

NASA Astrophysics Data System (ADS)

We study the analyticity of the partition function of the hard hexagon model in the complex fugacity plane by computing zeros and transfer matrix eigenvalues for large finite size systems. We find that the partition function per site computed by Baxter in the thermodynamic limit for positive real values of the fugacity is not sufficient to describe the analyticity in the full complex fugacity plane. We also obtain a new algebraic equation for the low density partition function per site.

Assis, M.; Jacobsen, J. L.; Jensen, I.; Maillard, J.-M.; McCoy, B. M.

2013-11-01

129

Fugacities of gases and some mineralogical reactions at very high pressures and temperatures (an extrapolation)  

Microsoft Academic Search

Fugacities of H2, N2, O2, CH4, H2O, H2S, NH3, CO, and CO2 are calculated on the basis of the extrapolation of the caloric properties, and those of the compressibility of substances into the region of pressures up to 2 Mbar and of temperatures up to 4000K. Several equilibrium mineralogical reactions are calculated. The most probable sequence of decreasing the magnitudes

I. A. Ostrovsky; B. N. Rizhenko

1978-01-01

130

Determination of compressibility factor and fugacity coefficient of hydrogen in studies of adsorptive storage  

Microsoft Academic Search

The compressibility factor (z) of hydrogen was evaluated from the experimental p–V–T data and calculated from equations of state, such as the SRK equation and BWR equation as well. The effect of z on the adsorbed amount calculated was demonstrated by the adsorption of hydrogen on 5A-zeolite. The compressibility factor and the fugacity coefficient of hydrogen were formulated based on

Li Zhou; Yaping Zhou

2001-01-01

131

Fixed-fugacity option for the EQ6 geochemical reaction path code  

SciTech Connect

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.

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

1984-12-20

132

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

PubMed

Two programs calculating oxygen transport parameters and hemodynamic values respectively are described. They may be used indifferently with HP 67 or HP 97 Hewlett Packard calculators. (Acta anaesth. belg., 1980, 31, 53-59). PMID:7457044

Laurent, M

1980-01-01

133

Hyperfine Structure of Oxygen Calculated by Many-Body Theory. II  

Microsoft Academic Search

Many-body perturbation theory is used to calculate the contributions to the hyperfine structure of atomic oxygen from the orbital, spin-dipolar, and quadrupole interactions. The resulting values for and are 4.56 a. u. and 5.170 a. u., respectively, which are in good agreement with those measured by Harvey. Our calculated value for is 4.216 a. u., which together

Hugh P. Kelly

1969-01-01

134

Semiempirical calculations of the oxygen equilibrium isotope effect on binding of oxamate to lactate dehydrogenase  

Microsoft Academic Search

Semiempirical methods have been used in an attempt to predict theoretically the experimentally observed value of 0.9840 for the oxygen isotope effect on binding of oxamate to lactate dehydrogenase. The overall strategy involved vibrational analysis of oxamate in two different environments; that of the active site residues and in aqueous solution. The comparison of calculated values with the experimentally determined

Ewa Gawlita; Vernon E. Anderson; Piotr Paneth

1994-01-01

135

First principles calculations of oxygen adsorption on the UN(0 0 1) surface  

Microsoft Academic Search

Fabrication, handling and disposal of nuclear fuel materials require comprehensive knowledge of their surface morphology and reactivity. Due to unavoidable contact with air components (even at low partial pressures), UN samples contain considerable amount of oxygen impurities affecting fuel properties. The basic properties of O atoms adsorbed on the UN(001) surface are simulated here combining the two first principles calculation

Yu. F. Zhukovskii; D. Bocharov; E. A. Kotomin; R. A. Evarestov; A. V. Bandura

2009-01-01

136

Evaluating fugacity models for trace components in landfill gas  

Microsoft Academic Search

A fugacity approach was evaluated to reconcile loadings of vinyl chloride (chloroethene), benzene, 1,3-butadiene and trichloroethylene in waste with concentrations observed in landfill gas monitoring studies. An evaluative environment derived from fictitious but realistic properties such as volume, composition, and temperature, constructed with data from the Brogborough landfill (UK) test cells was used to test a fugacity approach to generating

Sophie Shafi; Andrew Sweetman; Rupert L. Hough; Richard Smith; Alan Rosevear; Simon J. T. Pollard

2006-01-01

137

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

138

Calculation of the mixing chamber of an ejector chemical oxygen - iodine laser  

SciTech Connect

Gas parameters are calculated at the outlet of the mixing chamber of an ejector chemical oxygen-iodine laser with a nozzle unit consisting of nozzles of three types, which provides a total pressure of the active medium that substantially exceeds a pressure in the generator of singlet oxygen. This technique of forming the laser active medium substantially facilitates the ejection of the exhaust gas to the atmosphere by using a diffuser and single-stage vacuum systems based on water circulating pumps. (lasers, active media)

Zagidullin, M V; Nikolaev, V D [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2001-06-30

139

Fugacity coefficients of H sub 2 , CO sub 2 , CH sub 4 , H sub 2 O and of H sub 2 O-CO sub 2 -CH sub 4 mixtures: A virial equation treatment for moderate pressures and temperatures applicable to calculations of hydrothermal boiling  

SciTech Connect

Equations derived from a quadratic virial equation in pressure, with virial coefficients expressed as a function of temperature, are fitted to published P-V-T and solubility data to yield values of second and third virial coefficients for pure and mixed gases. These coefficients are not virial coefficients sensu stricto and are used to compute fugacity coefficients of pure H{sub 2}, H{sub 2}O, CO{sub 2} and CH{sub 4}, and of mixed H{sub 2}O, CO{sub 2} and CH{sub 4}, and to estimate enthalpies for these gases. For H{sub 2}, the P-T range of application is from 25 to 600 C and up to 3,000 bars, and for CH{sub 4}, from 16 to 350 C and up to 500 bars. For H{sub 2}O and CO{sub 2}, two P-T ranges are considered: below 350C, up to 500 bars, and from 450 to 1,000 C, up to 1,000 bars. The method presented here is limited to the P-T range of the fitted experimental data, and cannot represent accurately P-V-T data close to the critical region. This virial equation treatment yields simple analytical expressions that are suitable for multicomponent equilibrium calculations. Examples of equilibrium calculations between aqueous and gas phases show that ideal mixing of real gases is a sufficient approximation for modeling boiling in geothermal and epithermal systems. However, non-ideal mixing has to be considered for aqueous-gas systems at pressures much higher than the saturation pressure of pure water.

Spycher, N.F.; Reed, M.H. (Univ. of Oregon, Eugene (USA))

1988-03-01

140

Guide for Use of Computer Programs for the Calculation of Thermodynamic Properties of Oxygen and Nitrogen. (Second Edition).  

National Technical Information Service (NTIS)

This guide describes the calculation of thermodynamic properties of oxygen and nitrogen using recent formulations developed in the Center for Applied Thermodynamic Studies at the University of Idaho. The programs provide for the calculation of properties ...

R. T. Jacobsen R. B. Stewart

1976-01-01

141

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

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.

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

142

Electronic Structure Calculations of an Oxygen Vacancy in KH2PO4  

SciTech Connect

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

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

2005-02-18

143

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

SciTech Connect

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.

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

1983-08-01

144

Method to obtain the high contrast images of blood vessel for oxygen saturation calculation  

NASA Astrophysics Data System (ADS)

The skin illuminated of two lights at different wavelength can be applied to detect the oxygen saturation of human blood. Due to the absorption coefficient of oxy- (HbO2) and deoxy- (Hb) hemoglobin are different at the wavelength 660 nm and 890 nm, the transmitted and reflected light within the skin can be used to compute the oxygen saturation image of skin. However, the intensities of skin images illuminated by a 20 mW NIR-LED are too low to determine the position of blood vessel when acquired by the color CCD camera. In order to improve the disadvantages, a mono camera was used and the irradiated distance and angle between LED light and test hand were adjusted to acquire the higher resolution and contrast blood vessel images for the oxygen saturation calculation. In the experiment, we developed the suitable angle to irradiate NIR light is at 75 degrees because the reflected and scattered effect could be generated significantly from both vertical and horizontal direction. In addition, the best contrast vessel images can be obtained when the shutter time is set at 44.030 ms and the irradiated distance was at the range 140-160 mm due to the intensity ratio between tissue and vessel region is the highest and the intensities of image would not be saturated or become too low when these two parameters were adjusted slightly. In future, the proposed parameters and results can be applied to the oxygen saturation measurement in the clinical diagnosis.

Tsai, Hsin-Yi; Chen, Yi-Ju; Chang, Han-Chao; Huang, Kuo-Cheng

2013-06-01

145

Armalcolite stability as a function of pressure and oxygen fugacity  

Microsoft Academic Search

High-pressure experiments in a piston-cylinder apparatus with silver-palladium containers were conducted to study the stability of synthetic armalcolite, (Fe,Mg)Ti2O5, as a function of pressures up to 15 kbar at 1000, 1100, and 1200 C. Three armalcolite compositions were used, each with an initial Fe\\/(Fe + Mg) ratio of 0.5. Composition I contained no zirconium, whereas compositions II and III were

J. J. Friel; R. I. Harker; G. C. Ulmer

1977-01-01

146

A thermodynamic study on the pyrite-pyrrhotite-magnetite-water system at 300-500 degree C with relevance to the fugacity/concentration quotient of aqueous H sub 2 S  

SciTech Connect

Equilibrium concentrations of aqueous H{sub 2} and H{sub 2}S in the system composed of the pyrite-pyrrhotite-magnetite (PPM) buffer and water were measured at temperatures in the interval of 300-500{degree}C and pressures below 1 kbar, and the fugacity/concentration quotient of dilute aqueous H{sub 2}S was evaluated over the same P-T region. The necessary f{sub H{sub 2}S} values were calculated from the equilibrium constants of the gaseous reaction, H{sub 2} + 1/2S{sub 2} = H{sub 2}S, the H{sub 2} concentrations, fugacity/concentration quotients of aqueous H{sub 2} determined previously, and the f{sub S{sub 2}} of the PPM buffer. The temperature dependence of the f{sub S{sub 2}} was defined in this study after discussing where the best match is between the existing data on the f{sub S{sub 2}} of the pyrite-pyrrhotite buffer and on the solubility of H{sub 2}S in water. Oxygen fugacities of the PPM buffer were also calculated from the measured H{sub 2} concentrations and fitted. In conjunction with previously obtained experimental data on f{sub O{sub 2}} in volcanic rock-water systems, these results were applied to a few typical problems related to the f{sub O{sub 2}}-f{sub S{sub 2}} conditions in natural hydrothermal systems.

Kishima, Noriaki (Okayama Univ., Tottori-ken (Japan))

1989-09-01

147

Apparatus for Direct Fugacity Measurements on Mixtures Containing Hydrogen.  

National Technical Information Service (NTIS)

An apparatus has been designed and constructed to allow measurements of fugacities in gaseous mixtures containing hydrogen. The apparatus makes use of a semipermeable membrane to allow a direct measurement of the partial pressure of a permeating component...

T. J. Bruno

1985-01-01

148

Mass-Independent Fractionation of Oxygen Isotope in Earth Wind: First Principle Calculations for Photodissociation  

NASA Astrophysics Data System (ADS)

Mass-independently fractionated oxygen isotope were reported on metal particles extracted from Apollo lunar soils [1, 2], but these origins are still unknown. Since the substantial fraction of Earth-escaping O+ flux (Earth Wind, EW hereafter), comparable to the amount of the anomalous oxygen implanted on the metal particles, could reach the lunar surface [3], Ozima et al. [4] suggested that EW may be responsible to the anomalous oxygen. The purpose is to test this EW hypothesiss, we study oxygen isotopic ratios of O+ at the upper atmosphere. From quantum chemical calculations of photo-dissociation of O2, we show the results in mass-independent isotopic fractionation of oxygen, thereby in conformity with the EW hypothesis. First principles reaction dynamics simulations were performed to compute the photolysis rate for the B3?u- ? X3?g- electronic transition, for Schumann-Runge band. With the assumption of the Born-Oppenheimer approximation, we performed the wave-packet dynamics for the nuclei-motion in the potential energy curves determined by the first step calculation. Quantum chemical program package [5] was used for the first step calculation, and the quantum dynamics was carried out by our own program package. Assuming the quantum yield of the corresponding photolysis is unity, the photo-absorption cross section can be correlated with the photolysis rate. Therefore, following the time dependent approach, the autocorrelation function (A(t) = ) was numerically computed by the second step calculation. Finally, the theoretical spectrum as a function of wavelength of excitation light was estimated by the Fourier transform of the autocorrelation function A(t) [6]. Calculated absorption cross sections for C16O showed similar wavelength dependence with experiment [7], although the absolute magnitude was yet to be calibrated for a quantitative comparison. Assuming Boltzmann distribution at 1200 K, we estimated enrichment factors defined as ??(?)/?16(?) - 1 (i = 17, 18) using the above calculated cross sections. Assuming SMOW for the initial oxygen isotopic composition, the isotopic ratios of O atom dissociated from O2 are ?17O = 5.62‰, ?18O = 3.53‰, ?17O = 3.8‰, suggesting large mass-independent isotopic fractionation in photo-dissociation of CiO. Numerical values of isotopic fractionation (e.g. ?17O) can be obtained by solving photochemical reaction equations in the thermosphere conditions (>100 km) with the above estimated dissociation rates, where effective O+ pickup is likely to take place. We are currently working on the latter problem with hopes that this would test the EW hypothesis. References: [1] Ireland et al., 2006, Nature, 440:776. [2] Hashizume & Chaussidon, 2009, GCA, 73:3038. [3] Seki et al., 2001, Science, 291:1939. [4] Ozima et al., 2008, PNAS, 105:17654. [5] Werner & Knowles, http://www.molpro.net. [6] Heller, 1978, J. Chem. Phys., 68:2066. [7] Ackermann et al., 1970, Planet. Space Sci., 18:1639.

Yamada, A.; Nanbu, S.; Kasai, Y.; Ozima, M.

2009-12-01

149

Density functional theory calculations for the oxygen dissociation on nitrogen and transition metal doped graphenes  

NASA Astrophysics Data System (ADS)

Oxygen adsorption and dissociation on a pristine graphene, nitrogen doped graphene (N-graphene), and transition metal doped graphene (M-graphene) are studied with density functional theory calculations coupled with nudged elastic band (NEB) method. Four 3d transition metals (Fe, Co, Ni, and Cu) are selected as the doping atoms. The O binding energies on the Co-graphene and Ni-graphene have intermediate strength. The O2 dissociation barriers for these two types of doped graphenes are also lower than that on the pristine graphene and N-graphene. The Co and Ni doped graphenes are predicted to be promising ORR catalysts.

Zheng, Yongping; Xiao, Wei; Cho, Maenghyo; Cho, Kyeongjae

2013-10-01

150

Third Bose fugacity coefficient in one dimension, as a function of asymptotic quantities  

SciTech Connect

In one of the very few exact quantum mechanical calculations of fugacity coefficients, [L.R. Dodd, A.M. Gibbs. J. Math. Phys. 15 (1974) 41] obtained b{sub 2} and b{sub 3} for a one dimensional Bose gas, subject to repulsive delta-function interactions, by direct integration of the wave functions. For b{sub 2}, we have shown [A. Amaya-Tapia, S.Y. Larsen, M. Lassaut. Mol. Phys. 103 (2005) 1301-1306. < (arXiv:physics/0405150)>] that Dodd and Gibbs' result can be obtained from a phase shift formalism, if one also includes the contribution of oscillating terms, usually contributing only in one dimension. Now, we develop an exact expression for b{sub 3}-b{sub 3}{sup 0} (where b{sub 3}{sup 0} is the free particle fugacity coefficient) in terms of sums and differences of three-body eigenphase shifts. Further, we show that if we obtain these eigenphase shifts in a Distorted-Born approximation, then, to first order, we reproduce the leading low temperature behaviour, obtained from an expansion of the twofold integral of Dodd and Gibbs. The contributions of the oscillating terms cancel. The formalism that we propose is not limited to one dimension, but seeks to provide a general method to obtain virial coefficients, fugacity coefficients, in terms of asymptotic quantities. The exact one dimensional results allow us to confirm the validity of our approach in this domain.

Amaya-Tapia, A., E-mail: jano@fis.unam.mx [Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico AP 48-3, Cuernavaca, Mor. 62251 (Mexico); Larsen, S.Y. [Department of Physics, Temple University, Philadelphia, PA 19122 (United States); Lassaut, M. [Institut de Physique Nucleaire, IN2P3-CNRS, Universite Paris-Sud 11, F-91406 Orsay Cedex (France)

2011-02-15

151

Third Bose fugacity coefficient in one dimension, as a function of asymptotic quantities  

NASA Astrophysics Data System (ADS)

In one of the very few exact quantum mechanical calculations of fugacity coefficients, [L.R. Dodd, A.M. Gibbs. J. Math. Phys. 15 (1974) 41] obtained b2 and b3 for a one dimensional Bose gas, subject to repulsive delta-function interactions, by direct integration of the wave functions. For b2, we have shown [A. Amaya-Tapia, S.Y. Larsen, M. Lassaut. Mol. Phys. 103 (2005) 1301-1306. ] that Dodd and Gibbs' result can be obtained from a phase shift formalism, if one also includes the contribution of oscillating terms, usually contributing only in one dimension. Now, we develop an exact expression for b3-b30 (where b30 is the free particle fugacity coefficient) in terms of sums and differences of three-body eigenphase shifts. Further, we show that if we obtain these eigenphase shifts in a Distorted-Born approximation, then, to first order, we reproduce the leading low temperature behaviour, obtained from an expansion of the twofold integral of Dodd and Gibbs. The contributions of the oscillating terms cancel.The formalism that we propose is not limited to one dimension, but seeks to provide a general method to obtain virial coefficients, fugacity coefficients, in terms of asymptotic quantities. The exact one dimensional results allow us to confirm the validity of our approach in this domain.

Amaya-Tapia, A.; Larsen, S. Y.; Lassaut, M.

2011-02-01

152

Workshop on Oxygen in the Terrestrial Planets. Held in Santa Fe, New Mexico on July 20-23, 2004.  

National Technical Information Service (NTIS)

Partial Contents: Experimental Constraints on Oxygen and Other Light Element Partitioning During Planetary Core Formation; The Effect of Oxygen Fugacity on Large-Strain Deformation and Recrystallization of Olivin; Plagioclase-Liquid Trace Element Oxygen B...

2004-01-01

153

Fugacity coefficients of H sub 2 , CO sub 2 , CH sub 4 , H sub 2 O and of H sub 2 O-CO sub 2 CH sub 4 mixtures: A virial equation treatment for moderate pressures and temperatures applicable to calculations of hydrothermal boiling  

Microsoft Academic Search

Equations derived from a quadratic virial equation in pressure, with virial coefficients expressed as a function of temperature, are fitted to published P-V-T and solubility data to yield values of second and third virial coefficients for pure and mixed gases. These coefficients are not virial coefficients sensu stricto and are used to compute fugacity coefficients of pure Hâ, HâO, COâ

N. F. Spycher; M. H. Reed

1988-01-01

154

Concentration-distance profiles resulting from the hydrogen-charging of metal lattices under high fugacity conditions  

SciTech Connect

In the hydrogenation of metals under high fugacity conditions (such as electrolytic charging), non-steady state diffusion produces concentration-distance profiles which may not be calculated by assuming simple diffusion behavior. Such profiles have been calculated using finite difference methods by considering specific models for the concentration-perturbation of the appropriate jump activation barriers. The results show that much greater H concentrations are produced for a given penetration distance than would be expected by assuming fickian diffusion.

Zang, D.; Mclellan, R.B. [William Marsh Rice Univ., Houston, TX (United States). Dept. of Mechanical Engineering

1999-05-28

155

New calculation method of neutron kerma coefficients for carbon and oxygen below 30 MeV  

SciTech Connect

On the basis of the statistical theory of a neutron-induced light nucleus reaction, a new kerma coefficient calculation formula, expressed as k{sub {phi}}=NijkE{sub ijk}(E{sub n}){sigma}{sub ijk}(E{sub n}), is developed in this paper. In an analysis of the n+{sup 12}C and n+{sup 16}O reactions below 30 MeV, the average energies E{sub ijk} of emitted particles of all kinds in the laboratory frame are derived in detail for different channels, allowing an exact energy balance. The optical model parameters of neutron and charged particles, which had reproduced very well the outgoing neutron double-differential cross sections in our early works, are used to obtain the cross sections {sigma}{sub ijk}. The calculated partial, elastic recoil, and total kerma coefficients for carbon and oxygen are consistent with existing experimental kerma coefficient data. The elastic cross sections and the first Legendre coefficients of elastic angular distribution derived from EBDF/B-VIIb3 are used in this paper to improve significantly the elastic recoil and total kerma coefficients.

Sun Xiaojun; Qu Wenjing; Duan Junfeng; Zhang Jingshang [China Institute of Atomic Energy, P.O. Box 275(41), Beijing 102413 (China); College of Physics and Electronic Engineering, Guangxi Normal University, Guilin 541004 (China)

2008-11-15

156

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

National Technical Information Service (NTIS)

Oxygen consumption can be difficult and time consuming to measure. At the present time there does not exist an accurate method of estimating oxygen consumption during exercise at varying workloads. This study examined the relationship between minute venti...

T. S. Neuman K. M. Moser

1979-01-01

157

A model of oxygen uptake kinetics in response to exercise: Including a means of calculating oxygen demand\\/deficit\\/debt  

Microsoft Academic Search

We present a new model of the underlying dynamics of the oxygen uptake \\u000a $$\\\\dot VO_2 (\\\\upsilon , t)$$\\u000a kinetics for various exercise intensities. This model is in the form of a set of nonlinear coupled vector fields for the\\u000a \\u000a $$\\\\ddot VO_2 (\\\\upsilon , t)$$\\u000a and \\u000a $$\\\\dot \\\\upsilon $$\\u000a , the derivative of the exercise intensity with respect to time. We

J. R. Stirling; M. S. Zakynthinaki; B. Saltin

2005-01-01

158

A Graphical Representation for the Fugacity of a Pure Substance  

ERIC Educational Resources Information Center

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…

Book, Neil L.; Sitton, Oliver C.

2010-01-01

159

A Graphical Representation for the Fugacity of a Pure Substance  

ERIC Educational Resources Information Center

|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…

Book, Neil L.; Sitton, Oliver C.

2010-01-01

160

Low-fugacity asymptotic expansion for classical lattice dipole gases  

Microsoft Academic Search

We consider a classical dipole gas in the grand canonical ensemble. We prove that in dimensions greater than or equal to three, and for all temperatures, the free energy and the charges-dipoles correlation functions have an expansion in powers of z, the fugacity of the system, which is asymptotic to all orders. We also give some information about the decay

J. R. Fontaine

1981-01-01

161

Exact State and Fugacity Equations for the Ideal Quantum Gases  

Microsoft Academic Search

The fully relativistic expressions for the density, pressure, and energy density of the ideal quantum gases are solved exactly for the fugacity. This allows the exact, fully relativistic equations of state to be obtained for the ideal Fermi and Bose gases. All these expressions are studied in detail, including a discussion of physical implications and various limiting cases.

Michael Martin Nieto

1970-01-01

162

Low-fugacity asymptotic expansion for classical lattice dipole gases  

Microsoft Academic Search

We consider a classical dipole gas in the grand canonical ensemble. We prove that in dimensions greater than or equal to three, and for all temperatures, the free energy and the charges-dipoles correlation functions have an expansion in powers ofz, the fugacity of the system, which is asymptotic to all orders. We also give some information about the decay of

J. R. Fontaine

1981-01-01

163

Oxygen vacancy formation and migration in Ce1-xZrxO2 catalyst: A DFT+U calculation  

NASA Astrophysics Data System (ADS)

Spin-polarized density functional theory with the inclusion of on-site Coulomb correction (DFT+U) calculation is carried out to study the oxygen vacancy and migration of Ce1-xZrxO2 in a series of Ce/Zr ratios. Substitution of Zr4+ ion in CeO2 creates activated oxygen in Ce1-xZrxO2, leading to higher oxygen storage capacity (OCS) compared to CeO2 due to its structural and electronic modifications. It is found that the oxygen vacancy formation energy (Ef) is lowered even by small amounts of zirconia; the oxide with a content of 50% zirconia exhibits the lowest Ef and the best OCS. This indicates that the O vacancy is most easily created near the Zr centers. In addition, the activation energy calculations for oxygen vacancy migration around Zr dopant show facile oxygen migration through the Ce1-xZrxO2 materials, especially for 50% Zr-doped ceria. The detailed electronic analysis is also carried out to gain insights into the higher OCS of the Ce1-xZrxO2 catalyst.

Chen, Hsin-Tsung; Chang, Jee-Gong

2010-06-01

164

Fugacity approach to evaluate the sediment-water diffusion of polycyclic aromatic hydrocarbons.  

PubMed

Diffusion is an important process for sediment-water exchange and plays a vital role in controlling water quality. Fugacity fraction (ff) was used to estimate the sediment-water diffusion of polycyclic aromatic hydrocarbons (PAHs) between seawater and surficial sediment. A total of 33 surface sediment and sea water samples were collected concurrently from the northeast coastal area in China and 25 PAHs were analyzed including the alkylated and chlorated PAHs. Fugacity fraction was calculated based on the PAH concentrations in water and sediment, octanol-water partition coefficient of PAHs, organic matter content in sediment, and density of sediment. The calculated results showed that ff increased with decreasing molecular weight of PAHs. The low molecular weight PAHs (2-3 rings) transferred from sediment to water and the sediment acted as a secondary source to the water. The medium molecular weight PAHs (4-5 rings) were close to the sediment-water equilibrium and the transfer tendency shifted between sediment and water. The high molecular weight PAHs (5-6 rings) transferred from water into sediment and the sediment acted as a sink. Soot carbon and the difference of PAH concentrations between sediment and water were found to be important factors affecting the sediment-water diffusion. This study provided new insight into the process of sediment-water diffusion, which has a great influence on the quality of water, especially in severely-polluted sediment areas. PMID:21552633

Wang, De-Gao; Alaee, Mehran; Byer, Jonathan; Liu, Yong-Jun; Tian, Chong-Guo

2011-05-09

165

“Dead Zone” dynamics in Lake Erie: the importance of weather and sampling intensity for calculated hypolimnetic oxygen depletion rates  

Microsoft Academic Search

Calculated hypolimnetic oxygen depletion (HOD) rates depend not only on environmental factors but also logistical ones. In\\u000a particular, lack of understanding of the effects of weather in addition to how sampling effort determines calculated HOD rates\\u000a complicates ecological understanding and environmental management of lake ecosystems. To better determine the roles of weather\\u000a and sampling effort, we combined (1) weekly measurements

Joseph D. Conroy; Leon Boegman; Hongyan Zhang; William J. Edwards; David A. Culver

2011-01-01

166

Mass-Independent Fractionation of Oxygen Isotope in Earth Wind: First Principle Calculations for Photodissociation  

Microsoft Academic Search

Mass-independently fractionated oxygen isotope were reported on metal particles extracted from Apollo lunar soils [1, 2], but these origins are still unknown. Since the substantial fraction of Earth-escaping O+ flux (Earth Wind, EW hereafter), comparable to the amount of the anomalous oxygen implanted on the metal particles, could reach the lunar surface [3], Ozima et al. [4] suggested that EW

A. Yamada; S. Nanbu; Y. Kasai; M. Ozima

2009-01-01

167

Relativistic Calculation of Transition Probabilities for 557.7 nm and 297.2 nm Emission Lines in Oxygen  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

168

A fugacity-based indoor residential pesticide fate model  

SciTech Connect

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.

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

2002-06-01

169

Hydrogen component fugacities in binary mixtures with ethane: Temperature dependence  

NASA Astrophysics Data System (ADS)

The fugacity coefficients of hydrogen in binary mixtures with ethane were measured using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane through which hydrogen, but not ethane, can penetrate. Measurement of the gas pressures inside and outside of the membrane allows a direct measurement of the hydrogen component fugacity coefficient at a given temperature and binary-mixture mole fraction. In this paper, results are reported at 101, 116, 141, 151, 160, and 190°C. In each case the total pressure of the mixture was maintained at 3.41 MPa. The qualitative features of the measurements are discussed and comparisons are made with predictions obtained from the Redlich-Kwong, Peng-Robinson, and extended corresponding-states models.

Bruno, T. J.; Schroeder, J. A.

1987-07-01

170

Hydrogen component fugacities in binary mixtures with ethane: temperature dependence  

SciTech Connect

The fugacity coefficients of hydrogen in binary mixtures with ethane were measured using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane through which hydrogen, but not ethane, can penetrate. Measurement of the gas pressures inside and outside of the membrane allows a direct measurement of the hydrogen component fugacity coefficient at a given temperature and binary-mixture mole fraction. In this paper, results are reported at 101, 116, 141, 151, 160, and 190/sup 0/C. In each case the total pressure of the mixture was maintained at 3.41 MPa. The qualitative features of the measurements are discussed and comparisons are made with predictions obtained from the Redlich-Kwong, Peng-Robinson, and extended corresponding-states models.

Bruno, T.J.; Schroeder, J.A.

1987-07-01

171

CALCULATIONS OF OXYGEN TRANSPORT BY RED BLOOD CELLS AND HEMOGLOBIN SOLUTIONS IN CAPILLARIES  

Microsoft Academic Search

A theoretical model is developed to investigate the influence of hemoglobin-based oxygen carriers (HBOCs) on oxygen transport in capillary-size vessels. A discrete cell model is presented with red blood cells (RBCs) represented in their realistic parachute shape flowing in a single file through a capillary. The model includes the free and Hb-facilitated transport of O2 and Hb - O2 kinetics

Arjun Vadapalli; Daniel Goldman; Aleksander S. Popel

2002-01-01

172

Calculation of additional heart rates using oxygen consumption and carbon dioxide production: A comparative analysis  

Microsoft Academic Search

Research, to date, on the occurrence of additional heart rates during behavioral stressors has employed oxygen consumption\\u000a as the index of metabolic activity. Although this is the obvious first choice, in certain situations measures of carbon dioxide\\u000a production may be more readily obtained. The analysis presented in this paper explored the intuitively appealing notion that,\\u000a since oxygen consumption and carbon

Julian F. Thayer; L. J. P. van Doornen; J. Rick Turner

1991-01-01

173

Convergence of Fugacity Expansions for Fluids and Lattice Gases  

Microsoft Academic Search

Upper and lower bounds are obtained for R(V), the radius of convergence of the Mayer expansion V?lbl(V)zl expressing the logarithm of the classical grand partition function for a finite volume V as a power series in the fugacity z. The particles in V interact only through two-body forces whose potential &phgr;(r) satisfies s?1 ?i

Oliver Penrose

1963-01-01

174

CHEMFRANCE: A regional level iii fugacity model applied to France  

Microsoft Academic Search

CHEMFRANCE, a computer model allowing to estimate the environmental fate of organic chemicals in France, is presented. This multimedia model is represented by six bulk compartments (i.e., air, surface water, soil, bottom sediment, groundwater, coastal water), and by ten subcompartments. The model employs the fugacity concept and requires information on chemical properties (i.e., molecular weight, aqueous solubility, vapor pressure, n-octanol\\/water

W. Karcher

1995-01-01

175

Ferromagnetism in Nd-doped ZnO nanowires and the influence of oxygen vacancies: ab initio calculations.  

PubMed

Room-temperature ferromagnetism (RTFM) has been achieved in rare earth (RE) element doped ZnO nanostructures, while the mechanism of RTFM is still under debate. In this work, we investigated the electronic structure and magnetic properties of Nd-doped ZnO nanowires, and the influence of oxygen vacancies by using ab initio calculations. The impurity Nd atoms prefer to substitute the surface Zn sites and be ferromagnetically coupled with a moment of ?3.0 ?B per Nd in the doped ZnO nanowires, through a superexchange interaction mediated by the oxygen ions. More interestingly, the surface oxygen vacancy can greatly enhance the stability of the ferromagnetic state via the "local carriers" of Nd- and Zn-s electrons, which accounts for the room-temperature ferromagnetism in the Nd-doped ZnO nanowires. This mechanism and analysis can be applied to other rare earth element doped semiconductor nanostructures. PMID:24042194

Chen, Qian; Wang, Jinlan

2013-10-01

176

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

National Technical Information Service (NTIS)

The oxygen consumption technique is emerging as a powerful tool for determining the heat release rate in a number of diverse fire test applications, including room fire tests, fire endurance tests, the ASTM E 84 tunnel test, and various heat release rate ...

W. J. Parker

1982-01-01

177

First principles calculations of oxygen adsorption on the UN(0 0 1) surface  

Microsoft Academic Search

Fabrication, handling and disposal of nuclear fuel materials require comprehensive knowledge of their surface morphology and reactivity. Due to unavoidable contact with air components (even at low partial pressures), UN samples contain considerable amount of oxygen impurities affecting fuel properties. In this study we focus on reactivity of the energetically most stable (001) substrate of uranium nitride towards the atomic

Yuri F. Zhukovskii; Dmitry Bocharov; Eugene Alexej Kotomin; Robert Evarestov; Andrey V. Bandura

2009-01-01

178

Oxygen potential of diamond formation in the lower mantle  

NASA Astrophysics Data System (ADS)

Thermodynamic calculations have shown that when a metallic phase arising due to ferroan ion disproportionation is contained in lower-mantle rocks, carbon occurs as iron carbide and the oxygen fugacity corresponds to the equilibrium of ferropericlase with Fe-Ni alloy. The typical values of oxygen fugacity in zones of diamond formation in the lower mantle lie between the iron-wüstite buffer and six logarithmic units above this level. The processes that proceed in the lower mantle give rise to variation of f_{O_2 } within several orders of magnitude above the elevated f_{O_2 } values, which are necessary for the formation of diamond, as compared with a common level typical of the lower mantle. The mechanisms responsible for redox differentiation in the lower mantle comprise the subduction of oxidized crustal material, mechanical separation of metallic phase and silicate-oxide mineral assemblage enriched in ferric ions, as well as transfer of fused silicate material presumably enriched in Fe3+ through the mantle.

Ryabchikov, I. D.; Kaminsky, F. V.

2013-02-01

179

Calculation of oxygen isotope fractionation between uranium dioxide, uranium trioxide and water  

Microsoft Academic Search

Reduced partition function ratios (r.p.f.r) for uranium dioxide and uranium trioxide are calculated using selected crystal field models for optical modes and Debye functions for acoustic modes at temperatures ranging from 0 to 1000°C. The contribution of the acoustic modes is negligibly small in the calculated values of r.p.f.r. in all temperature ranges. The uncertainty of the r.p.f.r. is calculated

Keiko Hattori; Stanislaw Halas

1982-01-01

180

PLAGIOCLASE-LIQUID TRACE ELEMENT OXYGEN BAROMETRY AND OXYGEN BEHAVIOUR IN CLOSED AND OPEN SYSTEM MAGMATIC PROCESSES. Dante Canil  

Microsoft Academic Search

Introduction: There are several measurements of the oxygen fugacity recorded by magmas, and related con- cern about the behaviour of oxygen in magmas. Do magmas exchange oxygen in an open process through homogeneous equilibria, or do they remain closed sys- tems along their liquid line of descent? Evidence for mixing of several magma batches in many magma types suggests truly

James Thom

2004-01-01

181

Quantum Calculations of Quenching of Vibrationally Excited OH in Collisions With Atomic Oxygen  

NASA Astrophysics Data System (ADS)

Reaction between atomic hydrogen and ozone is an important source of vibrationally excited OH in the mesosphere. Radiative decay of vibrationally excited OH competes with collisional quenching by atomic and molecular oxygen and to a lesser extent by molecular nitrogen. Here we present the first explicit quantum mechanical investigation of quenching of vibrationally excited OH(v=1) by collisions with atomic oxygen. We explore both non-reactive quenching to OH(v=0) and reactive collisions leading to H+O2. It is found that the branching between reactive and non-reactive channels is strongly influenced by long-range dipole-quadrupole forces in the O+OH channel. The computed results are found to be in close agreement with available experimental results. This work was supported by NSF grant ATM-0635715.

Naduvalath, B.; Juanes-Marcos, J.; Quéméner, G.; Kendrick, B. K.

2011-12-01

182

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)

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.

Kaiser, J.; Abe, O.

2011-10-01

183

Limiting oxygen concentration evaluation in flammable gaseous mixtures by means of calculated adiabatic flame temperatures  

Microsoft Academic Search

The limiting oxygen concentration (LOC) of fuel–air–inert premixed gaseous systems are usually determined from measurements of explosion limits at progressive dilution with inert gas of fuel–air mixtures, which is a long and cumbersome procedure. An alternative procedure to evaluate LOC would be of great interest for all fields of activity involving the use of flammable mixtures, especially when less characterized

Domnina Razus; Maria Molnarne; Oliver Fuß

2004-01-01

184

A comparison of two methods for the calculation of accumulated oxygen deficit  

Microsoft Academic Search

The aim of this study was to compare accumulated oxygen deficit data derived using two different exercise protocols with the aim of producing a less time-consuming test specifically for use with athletes. Six road and four track male endurance cyclists performed two series of cycle ergometer tests. The first series involved five 10 min sub-maximal cycle exercise bouts, a VO2peak

Andrew Gardner; Mark Osborne; Shaun DAuria; David Jenkins

2003-01-01

185

“SIGMELTS”: A web portal for electrical conductivity calculations in geosciences  

NASA Astrophysics Data System (ADS)

Electrical conductivity measurements in the laboratory are critical for interpreting geoelectric and magnetotelluric profiles of the Earth's crust and mantle. In order to facilitate access to the current database on electrical conductivity of geomaterials, we have developed a freely available web application (SIGMELTS) dedicated to the calculation of electrical properties. Based on a compilation of previous studies, SIGMELTS computes the electrical conductivity of silicate melts, carbonatites, minerals, fluids, and mantle materials as a function of different parameters, such as composition, temperature, pressure, water content, and oxygen fugacity. Calculations on two-phase mixtures are also implemented using existing mixing models for different geometries. An illustration of the use of SIGMELTS is provided, in which calculations are applied to the subduction zone-related volcanic zone in the Central Andes. Along with petrological considerations, field and laboratory electrical data allow discrimination between the different hypotheses regarding the formation and rise from depth of melts and fluids and quantification of their storage conditions.

Pommier, A.; Le-Trong, E.

2011-09-01

186

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

Microsoft Academic Search

Volcanic gases collected during episode 1 of the Puu Oo eruption along the east rift zone of Kilauea Volcano, Hawaii, have uniform C-O-H-S-Cl-F compositions that are sharply depleted in CO 2 . The CO 2 -poor gases are typical of Type II volcanic gases ( and , 1985) and were emitted from evolved magma stored for a prolonged period of

T. M. Gerlach

1993-01-01

187

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

Microsoft Academic Search

Volcanic gases collected during episode 1 of the Puu Oo eruption along the east rift zone of Kilauea Volcano, Hawaii, have uniform C-O-H-S-Cl-F compositions that are sharply depleted in CO[sub 2]. The CO[sub 2]-poor gases are typical of Type II volcanic gases (GERLACH and GRAEBER, 1985) and were emitted from evolved magma stored for a prolonged period of time in

T GERLACH

1993-01-01

188

The bonding of ferrous iron to sulfur and oxygen in tetrahedral coordination: A comparative study using SCF X scattered wave molecular orbital calculations  

Microsoft Academic Search

Molecular quantum mechanical calculations have been performed on high-spin ferrous iron tetrahedrally coordinated to sulfur and oxygen, respectively. The molecular orbital energies obtained from the calculations are compared with experimental optical and X-ray emission spectra. Good agreement was found between calculated and experimental spectral transition energies for the optical absorption spectra of Fe 2+ in sphalerite, of Fe 2+ in

D. J. Vaughan; K. H. Johnson; J. A. Tossell

1974-01-01

189

Some Physical Properties of Compressed Gases. VI. The Fugacity of Carbon Dioxide  

Microsoft Academic Search

The Michels' compressibility data for carbon dioxide are smoothed and interpolated by graphical methods, and the fugacity is computed at certain integral pressures. The temperature range is from 0° to 150°C, and the pressure range from 0 to the neighborhood of 3000 atmos. Along all isotherms, the fugacity at first drops below the pressure, the ratio fp decreasing with p-a

W. Edwards Deming; Lola S. Deming

1939-01-01

190

Hydrogen component fugacities in binary mixtures with methane and propane  

NASA Astrophysics Data System (ADS)

The fugacity coefficients of hydrogen in binary mixtures with methane and propane were measured using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane. Hydrogen can penetrate and pass through the membrane, while the other component (in this case, methane or propane) cannot. At equilibrium, pure hydrogen will permeate into one “compartment” of the chamber, while the binary mixture occupies the other compartment. Thus, the pressure of pure hydrogen on one side approaches the partial pressure of hydrogen in the mixture on the other side of the membrane. This allows a direct measurement of the hydrogen component fugacity at a given mixture mole fraction. In this study, results are reported for measurements made on the hydrogen+propane binary at 80°C (353 K) and 130°C (403 K) and the hydrogen+methane binary at 80°C (353 K). All measurements were performed with a total mixture pressure of 3.45 MPa. The experimental results are compared with predictions from the Redlich-Kwong, Peng-Robinson, and extended corresponding-states models.

Bruno, T. J.; Hume, G. L.; Ely, J. F.

1986-09-01

191

Hydrogen component fugacities in binary mixtures with carbon dioxide  

NASA Astrophysics Data System (ADS)

The fugacity coefficients of hydrogen in binary mixtures with carbon dioxide were measured using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane. Hydrogen can penetrate and pass through the membrane, while the other component (in this case carbon dioxide) cannot. At equilibrium, pure hydrogen will permeate into one “compartment” of the chamber, while the binary mixture occupies the other compartment. Thus, the pressure of pure hydrogen on one side of the membrane approaches the partial pressure of hydrogen in the mixture on the other side of the membrane. This allows the direct measurement of the hydrogen component fugacity at a given mixture mole fraction. In this study, results are reported for measurements made on the hydrogen+carbon dioxide binary at 80°C (353 K), 130°C (403 K), 160°C (433 K), and 190°C (463 K), each at a total mixture pressure of 3.45 MPa. The experimental results are compared with predictions from the Redlich-Kwong, Peng-Robinson, and extended corresponding-states models.

Bruno, T. J.; Hume, G. L.

1986-09-01

192

Evaluating fugacity models for trace components in landfill gas.  

PubMed

A fugacity approach was evaluated to reconcile loadings of vinyl chloride (chloroethene), benzene, 1,3-butadiene and trichloroethylene in waste with concentrations observed in landfill gas monitoring studies. An evaluative environment derived from fictitious but realistic properties such as volume, composition, and temperature, constructed with data from the Brogborough landfill (UK) test cells was used to test a fugacity approach to generating the source term for use in landfill gas risk assessment models (e.g. GasSim). SOILVE, a dynamic Level II model adapted here for landfills, showed greatest utility for benzene and 1,3-butadiene, modelled under anaerobic conditions over a 10 year simulation. Modelled concentrations of these components (95,300 microg m(-3); 43 microg m(-3)) fell within measured ranges observed in gas from landfills (24,300-180,000 microg m(-3); 20-70 microg m(-3)). This study highlights the need (i) for representative and time-referenced biotransformation data; (ii) to evaluate the partitioning characteristics of organic matter within waste systems and (iii) for a better understanding of the role that gas extraction rate (flux) plays in producing trace component concentrations in landfill gas. PMID:16603294

Shafi, Sophie; Sweetman, Andrew; Hough, Rupert L; Smith, Richard; Rosevear, Alan; Pollard, Simon J T

2006-04-05

193

Fugacity-based indoor residential pesticide fate model.  

PubMed

Dermal and nondietary pathways are possibly important for exposure to pesticides used in residences. Limited data have been collected on pesticide concentrations in residential air and surfaces following application. Models may be useful for interpreting these data and to make predictions about concentrations in the home for other pesticides based on chemical properties. We present a dynamic mass-balance compartment model based on fugacity principles. The model includes air (both gas phase and aerosols), carpet, smooth flooring, and walls as model compartments. Six size fractions of particulate matter with different fate and transport properties are included. We determine the compartmental fugacity capacity and mass-transfer rate coefficients between compartments. We compare model results to chlorpyrifos air and carpet measurements from an independent study. For a comparison, we run the same simulation for diazinon and permethrin. We quantify the effect of parameter uncertainty and model uncertainties related to the source release rate and conduct a sensitivity analysis to determine which parameters contribute most to output uncertainty. In the model comparison to chlorpyrifos measurements, the model results are of the same order of magnitude as measured values but tend to overpredict the measured data, thus indicating the need for a better understanding of emissions from treated surfaces. PMID:15112818

Bennett, Deborah H; Furtaw, Edwin J

2004-04-01

194

Hydrogen component fugacities in binary mixtures with methane and propane  

SciTech Connect

The fugacity coefficients of hydrogen in binary mixtures with methane and propane were measured using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane. Hydrogen can penetrate and pass through the membrane, while the other component (in this case, methane or propane) cannot. At equilibrium, pure hydrogen will permeate into one ''compartment'' of the chamber, while the binary mixture occupies the other compartment. Thus, the pressure of pure hydrogen on one side approaches the partial pressure of hydrogen in the mixture on the other side of the membrane. This allows a direct measurement of the hydrogen component fugacity at a given mixture mole fraction. In this study, results are reported for measurements made on the hydrogen+propane binary at 80 degrees C (353 K) and 130 degrees C (403 K) and the hydrogen+methane binary at 80 degrees C (353 K). All measurements were performed with a total mixture pressure of 3.45 MPa. The experimental results are compared with predictions from the Redlich-Kwong, Peng-Robinson, and extended corresponding-states models.

Bruno, T.J.; Ely, J.F.; Hume, G.L.

1986-09-01

195

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

PubMed

A theoretical model is developed to investigate the influence of hemoglobin-based oxygen carriers (HBOCs) on oxygen transport in capillary-size vessels. A discrete cell model is presented with red blood cells (RBCs) represented in their realistic parachute shape flowing in a single file through a capillary. The model includes the free and Hb-facilitated transport of O2 and Hb-O2 kinetics in the RBC and plasma, diffusion of free O2 in the suspending phase, capillary wall, interstitium and tissue. A constant tissue consumption rate is specified that drives the simultaneous release of O2 from RBC and plasma as the cells traverse the capillary. The model mainly focuses on low capillary hematocrits and studies the effect of free hemoglobin affinity, cooperativity and concentration. The results are expressed in the form of cell and capillary mass transfer coefficients, or inverse transport resistances, that relate the spatially averaged flux of O2 coming out of the RBC and capillary to a driving force for O2 diffusion. The results show that HBOCs at a concentration of 7 g/dl reduce the intracapillary transport resistance by as much as 60% when capillary hematocrit is 0.2. HBOCs with high O2 affinity unload most O2 at the venular end, while those with low affinity supply O2 at the arteriolar end. A higher cooperativity did not favor O2 delivery due to the large variation in the mass transfer coefficient values during O2 unloading. The mass transfer coefficients obtained will be used in simulations of O2 transport in complex capillary networks. PMID:12066873

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

2002-05-01

196

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

NASA Astrophysics Data System (ADS)

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 has been applied to ilmenite-bearing assemblages in mantle xenoliths from kimberlites, including the metasomatic MARID (mica-amphibole-rutile-ilmenite-diopside) suite and a MORID (mica-orthopyroxene-rutile-ilmenite-diopside) vein, along with rutile-ilmenite assemblages in eclogites and in Granny Smith diopside megacrysts. The oxygen fugacities of MARID and MORID lie around the NNO buffer and are comparable to those in metasomatized spinel lherzolites. Most MARID and MORID assemblages yield a more oxidizing fO2 than the EMOD (enstatite-magnesite-olivine-diamond) buffer, such that MARID and MORID fluid or melt would tend to destroy diamond or graphite by oxidation.

Zhao, D.; Essene, E. J.; Zhang, Y.

1999-03-01

197

Density functional calculations of the absorption and magnetic properties of oxygen molecule on Au(110)  

NASA Astrophysics Data System (ADS)

Studies of the Kondo effect in molecular magnets and molecular junctions capture extensive attention of experimentalists and theorists. Our low temperature STM experiments revealed fascinating features of O2 on the reconstructed Au(110) surface. O2 forms alternating zig-zag and ying-yang rows on Au(110) and displays sizeable Kondo effect. Density functional calculations were performed to understand the driving force for the unusual structure and magnetic properties. Using the fixed triplet state of O2, the optimized atomic structure resembles the experimental topography well. The magnetization of O2 is stable with regular density functional calculations, 1.97 ?B from. We will discuss the pattern of Kondo clouds in view of molecular orbitals and density of states. Extensive experimental and theoretical data allow comprehensive understanding of the essence of spin polarization and spatial Kondo effect in molecular systems.

Wu, Ruqian; Zhang, Yanning; Cao, Juexian; Jiang, Ying; Ho, Wilson

2010-03-01

198

Calculated and measured oxygen consumption in mechanically ventilated surgical patients in the early post-operative period.  

PubMed

Oxygen consumption (VO2) measured by indirect calorimetry (Nellcor-Puritan-Bennett 7250; Carlsbad, CA, USA) has been compared with VO2 calculated by the Fick method in 22 volume-controlled ventilated general surgical patients in the early post-operative period. For 198 pairs of measurements, VO2 Fick and VO2 indirect calorimetry correlated significantly (y = 1.00x - 35.8, P = 0.0001, r = 0.77). VO2 indirect calorimetry was 212 +/- 32 mL min-1 and VO2 Fick was 177 +/- 41 mL min-1 (P = 0.0001). The bias was 35 +/- 26 mL min-1. This difference represents 16 +/- 13% of the total body VO2. VO2 calculated by the Fick method did not accurately predict VO2 measured by indirect calorimetry, and the two methods were not interchangeable. VO2 calculated by the Fick method underestimated VO2 as measured by indirect calorimetry by a systematic quantity that could be attributed, in part, to VO2 of the lung. Indirect calorimetry should be the preferred method for measuring total body VO2 in mechanically ventilated surgical patients. PMID:10084102

Brandi, L S; Bertolini, R; Santini, L

1999-01-01

199

Real-space calculation of the effects of oxygen and boron impurities on cohesion in nickel aluminides  

NASA Astrophysics Data System (ADS)

Understanding the physical factors which determine the strength of intermetallic alloys is an important problem for technology as well as for the science involved. In nickel aluminides some impurity atoms, e.g. boron, act as a cohesion enhancer which can improve the cohesion substantially; while some other atoms, e.g. oxygen, can destroy the cohesion, even when present in minute concentration. It is thus important to study the interaction between a single atomic impurity and its local intermetallic environment. We have studied this problem by using a combination of ab-initio and real-space (tight-binding) methods. We use a full-potential linear muffin-tin orbital (FP-LMTO) method to obtain an accurate set of tight-binding parameters which are then used as input parameters for a real-space computation using Haydock's local Green's function (recursion) method (Solid State Physics 35, 216--294, 1980). This combined method allows us to escape the limitation of the ab-initio supercell method and focus on the interaction of the single impurity atom with its nickel-aluminide environment. We will present the results of our calculation using this method for oxygen and boron impurities in NiAl and Ni_3Al.

Djajaputra, D.; Cooper, B. R.

2001-03-01

200

Airshed calculation of the sensitivity of pollutant formation to organic compound classes and oxygenates associated with alternative fuels  

SciTech Connect

This study uses a 3-D Eulerian photochemical model and an advanced chemical reaction mechanism to evaluate the sensitivity of pollutant levels to changes in emissions. In particular, the ozone forming potentials of classes of organic compounds are calculated, with particular emphasis on oxygenated organics associated with alternative fuels. Methanol, ethanol, MTBE, alkane and toluene emissions were found to add about one-fifth the ozone (on a carbon mass basis) as alkenes, aldehydes, non-toluene aromatics and ethene. On a per-carbon basis, formaldehyde added about ten times as much ozone as the least reactive organics tested. The results of the trajectory model-based study usually compare well with those found here. The pollution formation potentials can now be used in assessing the relative impact of various exhaust gas compositions.

McNair, L.; Russell, A.; Odman, M.T. (Carnegie Mellon Univ., Pittsburgh, PA (United States))

1992-02-01

201

LETTER TO THE EDITOR: Ab initio calculation of the local vibrational modes of the interstitial boron interstitial oxygen defect in Si  

NASA Astrophysics Data System (ADS)

The first stage in the anneal of interstitial boron below room temperature in Czochralski-grown Si (Cz-Si) is the formation of the interstitial boron-oxygen (BiOi) defect. First principles modelling show that this defect has a structure similar to the interstitial carbon-oxygen complex. However, whereas the latter defect has been characterized by local vibrational mode infra-red spectroscopy, there is no information on the local vibrational modes of BiOi even though the defect is known to be a dominant interstitial boron defect in irradiated Cz-Si. Here, we carry out density functional calculations to determine its vibrational modes and respective isotope shifts, concluding that it possesses six local vibrational modes. As in the case of CiOi, we find an oxygen-related vibrational mode with frequency far below the 1136 cm-1 of the oxygen interstitial, characteristic of the three-fold coordinated oxygen.

Carvalho, A.; Jones, R.; Coutinho, J.; Briddon, P. R.

2005-05-01

202

Modeling urban films using a dynamic multimedia fugacity model.  

PubMed

A thin film coats impervious urban surfaces that can act as a source or sink of organic pollutants to the greater environment. We review recent developments in the understanding of film and film-associated pollutant behavior and incorporate them into an unsteady-state version of the fugacity based Multimedia Urban Model (MUM), focusing on detailed considerations of surface film dynamics. The model is used to explore the conditions under which these atmospherically-derived films act as a temporary source of chemicals to the air and/or storm water. Assuming film growth of 2.1 nm d(-1) (Wu et al., 2008a), PCB congeners 28 and 180 reach air-film equilibrium within hours and days, respectively. The model results suggest that the film acts as a temporary sink of chemicals from air during dry and cool weather, as a source to air in warmer weather, and as a source to storm water and soil during rain events. Using the downtown area of the City of Toronto Canada, as a case study, the model estimates that nearly 1 g d(-1) of ?(5)PCBs are transferred from air to film to storm water. PMID:22280983

Csiszar, Susan A; Diamond, Miriam L; Thibodeaux, Louis J

2012-01-26

203

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

PubMed

The fugacities, concentrations, or inventories of pollutants in environmental compartments as determined by multimedia environmental fate models of the Mackay type can be superimposed on each other. This is true for both steady-state (level III) and dynamic (level IV) models. Any problem in multimedia fate models with linear, time-invariant transfer and transformation coefficients can be solved through a superposition of a set of n independent solutions to a set of coupled, homogeneous first-order differential equations, where n is the number of compartments in the model. For initial condition problems in dynamic models, the initial inventories can be separated, e.g. by a compartment. The solution is obtained by adding the single-compartment solutions. For time-varying emissions, a convolution integral is used to superimpose solutions. The advantage of this approach is that the differential equations have to be solved only once. No numeric integration is required. Alternatively, the dynamic model can be simplified to algebraic equations using the Laplace transform. For time-varying emissions, the Laplace transform of the model equations is simply multiplied with the Laplace transform of the emission profile. It is also shown that the time-integrated inventories of the initial conditions problems are the same as the inventories in the steady-state problem. This implies that important properties of pollutants such as potential dose, persistence, and characteristic travel distance can be derived from the steady state. PMID:11482677

Hertwich, E G

2001-08-01

204

Evaluating the multimedia fate of organic chemicals: A level III fugacity model  

SciTech Connect

A multimedia model is developed and applied to selected organic chemicals in evaluative and real regional environments. The model employs the fugacity concept and treats four bulk compartments: air, water, soil, and bottom sediment, which consist of subcompartments of varying proportions of air, water, and mineral and organic matter. Chemical equilibrium is assumed to apply within (but not between) each bulk compartment. Expressions are included for emissions, advective flows, degrading reactions, and interphase transport by diffusive and non-diffusive processes. Input to the model consists of a description of the environment, the physical-chemical and reaction properties of the chemical, and emission rates. For steady-state conditions the solution is a simple algebraic expression. The model is applied to six chemicals in the region of southern Ontario and the calculated fate and concentrations are compared with observations. The results suggest that the model may be used to determine the processes that control the environmental fate of chemicals in a region and provide approximate estimates of relative media concentrations.

Mackay, D.; Paterson, S. (Univ. of Toronto, Ontario (Canada))

1991-03-01

205

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

NASA Astrophysics Data System (ADS)

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

Holland, Tim; Powell, Roger

1991-12-01

206

Electronic structure of {delta}-Ta{sub 2}O{sub 5} with oxygen vacancy: ab initio calculations and comparison with experiment  

SciTech Connect

Electronic structure of oxygen vacancies in Ta{sub 2}O{sub 5} have been studied theoretically by first-principles calculations and experimentally by x-ray photoelectron spectroscopy. Calculations of {delta}-Ta{sub 2}O{sub 5} were performed using density functional theory within gradient-corrected approximation with the +U approach. Results indicate that the oxygen vacancy causes a defect level in the energy gap at 1.2 eV above the top of the valence band. To produce oxygen vacancies, amorphous films of Ta{sub 2}O{sub 5} were bombarded with Ar{sup +} ions. XPS results indicate that the Ar-ion bombardment leads to the generation of the oxygen vacancies in Ta{sub 2}O{sub 5} that characterize the peak at 2 eV above the valence band. The calculated spectrum of crystalline {delta}-Ta{sub 2}O{sub 5} demonstrates qualitative correspondence with the XPS spectrum of the amorphous Ta{sub 2}O{sub 5} film after Ar-ion bombardment.

Ivanov, Maxim V.; Perevalov, Timofey V.; Aliev, Vladimir S.; Gritsenko, Vladimir A. [A. V. Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk, 630090 (Russian Federation); Kaichev, Vasily V. [Boreskov Institute of Catalysis SB RAS, Novosibirsk, 630090 (Russian Federation)

2011-07-15

207

On the determination of the hydrogen fugacity in an environmental cell TEM facility  

SciTech Connect

The microscopic aspects of hydrogen embrittlement of a variety of materials have recently been studied by an in-situ deformation technique in the environmental cell of a high-voltage electron microscope. Although the pressure of gaseous H/sub 2/ or water-saturated gaseous H/sub 2/ introduced into the cell is monitored externally, there has been no measure of the hydrogen fugacity in the cell with the electron beam present. This fugacity may be significantly greater than the externally recorded pressure because of dissociation and/or ionization of molecular H/sub 2/ and/or H/sub 2/O. Evidence for this enhanced fugacity comes from the rapid electron-induced reaction of water vapor with aluminum, magnesium and silicon.

Bond, G.M.; Robertson, I.M.; Birnbaum, H.K.

1986-05-01

208

Calculation of hydrogen and oxygen uptake in fuel rod cladding during severe accidents using the integral diffusion method -- Preliminary design report  

SciTech Connect

Preliminary designs are described for models of hydrogen and oxygen uptake in fuel rod cladding during severe accidents. Calculation of the uptake involves the modeling of seven processes: (1) diffusion of oxygen from the bulk gas into the boundary layer at the external cladding surface, (2) diffusion from the boundary layer into the oxide layer, (3) diffusion from the inner surface of the oxide layer into the metallic part of the cladding, (4) uptake of hydrogen in the event that the cladding oxide layer is dissolved in a steam-starved region, (5) embrittlement of cladding due to hydrogen uptake, (6) cracking of cladding during quenching due to its embrittlement and (7) release of hydrogen from the cladding after cracking of the cladding. An integral diffusion method is described for calculating the diffusion processes in the cladding. Experimental results are presented that show a rapid uptake of hydrogen in the event of dissolution of the oxide layer and a rapid release of hydrogen in the event of cracking of the oxide layer. These experimental results are used as a basis for calculating the rate of hydrogen uptake and the rate of hydrogen release. The uptake of hydrogen is limited to the equilibrium solubility calculated by applying Sievert's law. The uptake of hydrogen is an exothermic reaction that accelerates the heatup of a fuel rod. An embrittlement criteria is described that accounts for hydrogen and oxygen concentration and the extent of oxidation. A design is described for implementing the models for hydrogen and oxygen uptake and cladding embrittlement into the programming framework of the SCDAP/RELAP5 code. A test matrix is described for assessing the impact of the proposed models on the calculated behavior of fuel rods in severe accident conditions. This report is a revision and reissue of the report entitled; ``Preliminary Design Report for Modeling of Hydrogen Uptake in Fuel Rod Cladding During Severe Accidents.''

Siefken, L.J.

1999-02-01

209

Multimedia environmental models (e.g. Fugacity models) as screening tools, e.g. in connection with life cycle assessments.  

National Technical Information Service (NTIS)

The aim of this paper is to discuss the use of fugacity models as screening tools in connection with life cycle assessments (LCA). The fugacity models are taken as examples of multimedia environmental models, parts of the discussion and conclusions will h...

G. Finnveden

1992-01-01

210

A fugacity based continuous and dynamic fate and transport model for river networks and its application to Altamaha River  

Microsoft Academic Search

In this paper, a continuous and dynamic fugacity-based contaminant fate and transport model is developed. The dynamic interactions among all phases in the physical domain are addressed through the use of the fugacity approach instead of the use of concentration as the unknown variable. The full form of Saint Venant equations is used in order to solve for the hydrodynamic

Sinem Gokgoz Kilic; Mustafa M. Aral

2009-01-01

211

Electronic structure of an oxygen vacancy in Al{sub 2}O{sub 3} from the results of Ab Initio quantum-chemical calculations and photoluminescence experiments  

SciTech Connect

The electronic structure of an oxygen vacancy in {alpha}-Al{sub 2}O{sub 3} and {gamma}-Al{sub 2}O{sub 3} is calculated. The calculation predicts an absorption peak at an energy of 6.4 and 6.3 eV in {alpha}-Al{sub 2}O{sub 3} and {gamma}-Al{sub 2}O{sub 3}, respectively. The luminescence and luminescence excitation spectra of amorphous Al{sub 2}O{sub 3} are measured using synchrotron radiation. The presence of a luminescence band at 2.9 eV and a peak at 6.2 eV in the luminescence excitation spectrum indicates the presence of oxygen vacancies in amorphous Al{sub 2}O{sub 3}.

Pustovarov, V. A. [Ural State Technical University (Russian Federation); Aliev, V. Sh.; Perevalov, T. V., E-mail: timson@isp.nsc.ru; Gritsenko, V. A., E-mail: grits@isp.nsc.ru [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Eliseev, A. P. [Russian Academy of Sciences, Institute of Geology and Mineralogy, Siberian Branch (Russian Federation)

2010-01-15

212

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

SciTech Connect

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

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

2001-03-23

213

Oxygen barometry of basaltic glasses based on vanadium valence determinations using synchrotron microXANES  

SciTech Connect

We describe here a new, non-destructive method for valence determinations of vanadium and oxygen fugacity estimates for basaltic glasses with spatial resolution of a few micrometers using synchrotron x-ray absorption near edge structure (XANES) spectroscopy. A promising proxy for oxygen fugacity is the valence of vanadium because it a large number of valence states in nature (2+, 3+, 4+ and 5+) and is ubiquitous in earth and planetary materials . We describe here a new, non-destructive method for valence determinations of vanadium and oxygen fugacity estimates for basaltic glasses with spatial resolution of a few micrometers using synchrotron x-ray absorption near edge structure (XANES) spectroscopy. Details of this method and applications to martian, lunar and terrestrial glasses are described and also in accompanying abstracts.

Sutton, S.R.; Karner, J.M.; Papike, J.J.; Delaney, J.S.; Shearer, C.K.; Newville, M.; Eng, P.; Rivers, M.; Dyar, M.D. (UNM); (Rutgers); (Mount Holyoke); (UC)

2004-10-27

214

A Compensated-Redlich-Kwong (CORK) equation for volumes and fugacities of CO 2 and H 2 O in the range 1 bar to 50 kbar and 100–1600°C  

Microsoft Academic Search

We present a simple virial-type extension to the modified Redlich-Kwong (MRK) equation for calculation of the volumes and fugacities of H2O and CO2 over the pressure range 0.001–50 kbar and 100 to 1400°C (H2O) and 100 to 1600°C (CO2). This extension has been designed to: (a) compensate for the tendency of the MRK equation to overestimate volumes at high pressures,

Tim Holland; Roger Powell

1991-01-01

215

Oxygen fugacity in the apatite-bearing intrusion of the Khibina complex  

Microsoft Academic Search

Based on the analysis of coexisting minerals (magnetite, ilmenite, titanite, and pyroxene), the temperature and redox conditions\\u000a of rock crystallization in the Khibina alkaline massif were estimated. Under the redox conditions typical of the Khibina complex,\\u000a the carbon speciation evolved as follows: CO2 in fluid and carbonate anions in melt at high temperatures; then, graphite formation; and, at lower temperatures,

I. D. Ryabchikov; L. N. Kogarko

2009-01-01

216

A Model to Predict Changes in S Solubility in Silicate Melts with Changes in Oxygen Fugacity  

NASA Astrophysics Data System (ADS)

The behavior if S in magmatic systems is of interest because of the impact of high-S explosive volcanism on climate, the controlling role of sulfides on the behavior of base and precious metals, and the potential use of S speciation as an indicator of the oxidation state of magmas. In silicate melts S can be present as sulfide (S2- ), sulfate (S6+) or a combination of both species. Significant differences exist in the amounts of S that can be dissolved in sulfide-saturated melts (e.g. melts coexisting with pyrrhotite or coexisting with an immiscible sulfide liquid) and sulfate-saturated melts (e.g. melts coexisting with anhydrite): sulfate-saturated melts typically containing several times more S than sulfide-saturated melts. The transition from sulfide-dominated to sulfate- dominated systems occur at fO2 in the range FMQ < fO2 < FMQ+2. In this interval both sulfide and sulfate species coexist; however, we know very little about the total amount of S that can be dissolved in silicate melts when S is present both as sulfide and sulfate. We derived a model for the total S content in silicate melts as a function of fO2 that accounts for the contribution of each species in the melt. For basaltic melts, the resulting equation is: {S}T = [S2-](1 + exp(2.23?FMQ-2.89)) where {S}T is the total mount of S that can be dissolved in the melt; [S2-] is the S content at sulfide saturation, and the factor [exp(2.23?FMQ-2.89)] accounts for the contribution to {S}T from S dissolved as (S6+). The model: (a) predicts an exponential increase in the total S content of sulfide- saturated silicate melts with increasing fO2, starting at about FMQ and up to the fO2 at which the melt reaches sulfate saturation; (b) explains the high S content found in some basaltic melt inclusions in olivine; (c) predicts low degrees of partial melting for the generation of S-rich, sulfide-undersaturated magmas at fO2 within the range of magma generation in supra-subduction zones and other metasomatized magma sources.

Jugo, P. J.; Wilke, M.; Woodland, A.

2007-05-01

217

Oxygen Fugacity of Basalts From Earth and Mars: Implications for Oxidation States of Terrestrial Planet Interiors  

Microsoft Academic Search

The oxidation state of a planetary interior plays an important role in the partitioning of elements between the planet's core and mantle, the geophysical properties of the mantle, the phase equilibria of igneous rocks, and the speciation of gases in the planet's atmosphere. Determining the oxidation state of the interior of the Moon, Mars, and differentiated asteroids is difficult, because

C. Herd

2004-01-01

218

CO 2 CO fluid inclusions in a composite peridotite xenolith: implications for upper mantle oxygen fugacity  

Microsoft Academic Search

Fluid inclusions occur in a composite xenolith from the Lunar Crater Volcanic Field, Nevada, U.S.A. The xenolith is an amphibole-bearing wehrlite that is cut by an andesine-amphibole vein. The compositions of individual fluid inclusions in both portions of the xenolith have been determined using microthermometry and micro Laser-Raman spectroscopy. Fluids in the host wehrlite are nearly pure CO2 (>99 mol%)

Steven C. Bergmanl; Jean Dubessy

1984-01-01

219

Mineral-melt partitioning of V and Sc at arcs: implications for mantle wedge oxygen fugacity  

Microsoft Academic Search

Arc basalts are demonstrably more oxidized than basalts derived from mid-ocean ridges; they follow calc-alkaline differentiation trends, release oxidized gases, concentrate redox-sensitive elements, and have higher Fe3+\\/?Fe. Whether this oxidized signature is imparted on the mantle wedge by the subducting slab or arises in the crust during differentiation has important implications for the long-term evolution of the mantle. The Fe3+\\/?Fe

C. M. Jackson; E. Cottrell; K. A. Kelley

2010-01-01

220

The role of fluorine and oxygen fugacity in the genesis of the ultrapotassic rocks  

Microsoft Academic Search

The effects of H2O, CO2, CH4 and HF on partial melting of a model phlogopite harzburgite mantle are considered with regard to the production of ultrapotassic magmas. Fluorine has a polymerising effect in H2O-poor conditions, but in the presence of abundant H2O where HF rather than F is dominant, the overall effect is depolymerisation. Methane also dissolves by forming (OH)-

Stephen F. Foley; Wayne R. Taylor; David H. Green

1986-01-01

221

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

Microsoft Academic Search

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,

C. McCammon; M. G. Kopylova

2004-01-01

222

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

ERIC Educational Resources Information Center

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.

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

2006-01-01

223

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

ERIC Educational Resources Information Center

|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.|

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

2006-01-01

224

On the mutual cancellation of cluster integrals in Mayer's fugacity series  

Microsoft Academic Search

Theorems are proved for each of two models representing purely repulsive interactions, the `Gaussian' and the `rigid line'. In both cases we study the fugacity series by starting with the complete diagram of l points connected by ½l(l-1) lines. For the Gaussian model, it is proved rigorously that the cluster integral corresponding to any diagram can be expressed as a

H N V Temperley

1964-01-01

225

Evaluating the multimedia fate of organic chemicals: A level III fugacity model  

Microsoft Academic Search

A multimedia model is developed and applied to selected organic chemicals in evaluative and real regional environments. The model employs the fugacity concept and treats four bulk compartments: air, water, soil, and bottom sediment, which consist of subcompartments of varying proportions of air, water, and mineral and organic matter. Chemical equilibrium is assumed to apply within (but not between) each

Donald Mackay; Sally Paterson

1991-01-01

226

Oxygen and hydrogen isotope partitioning between water liquid and vapor at elevated temperatures  

SciTech Connect

Oxygen and hydrogen isotope fractionation factors ({alpha}{sub {ell}-v}{sup O} and {alpha}{sub {ell}-v}{sup D}) between liquid water and water vapor have been calculated from vapor pressure ratio measurements and equations of state over the temperature range of 0 to 370{degree}C. These data are compared to the liquid-vapor fractionation factors determined by direct mass spectral measurements. The values for {alpha}{sub {ell}-v}{sup D} derived from the vapor pressure ratios are in close agreement with the experimental mass spectral measurements from 0 to 300{degree}C when fugacity coefficient and molar volume corrections are used. Deviations from the direct measurements above 0 to 300{degree}C are due to inadequacies in either (1) the magnitude of the molar volume correction for D{sub 2}O near the critical point, (2) the assumption of ideal mixing of the isotopic gases and liquids, and/or (3) the selection of 1.91 as the disproportionation factor for the formation of HDO. On the other hand, the {alpha}{sub {ell}-v}{sup O} values derived form vapor pressure data (no fugacity or molar volume corrections) agree closely with low-temperature direct measurement data, pass through some of Bottinga's (1968) high temperature results, and extrapolate smoothly to {alpha}{sub {ell}-v}{sup O} = 0 at the critical temperature as is required by thermodynamics. This behavior coupled with the fact that Bottinga's (1968) oxygen isotope results exhibit a large scatter, indicated that liquid-vapor oxygen isotope fractionation factors based on vapor pressure measurements should be applied to high-temperature geothermal systems rather than the direct mass spectral data. 15 refs., 2 figs., 1 tab.

Cole, D.R.; Wesolowski, D.J. (Oak Ridge National Lab., TN (USA))

1989-01-01

227

Modelling of pharmaceutical residues in Australian sewage by quantities of use and fugacity calculations  

Microsoft Academic Search

A conceptual model is presented for determining which currently prescribed pharmaceutical compounds are most likely to be found in sewage, and for estimating their concentrations, both in raw sewage and after successive stages of secondary sewage treatment. A ranking of the “top-50” pharmaceutical compounds (by total mass dispensed) in Australia over the 1998 calendar year was prepared. Information on the

Stuart J. Khan; Jerry E. Ongerth

2004-01-01

228

Differently substituted phthalocyanines: Comparison of calculated energy levels, singlet oxygen quantum yields, photo-oxidative stabilities, photocatalytic and catalytic activities  

Microsoft Academic Search

Zinc(II) and cobalt(II) phthalocyanines bearing different electron-donating or -withdrawing substituents were prepared. The following properties of these phthalocyanines were investigated: singlet oxygen quantum yields, photo-oxidative stabilities, photocatalytic activities (photooxidation of (S)-(?)-citronellol) and catalytic activities (oxidation of 2-mercaptoethanol). Furthermore, the positions of HOMO\\/LUMO energy levels of the ground state (S0), first excited singlet state (S1) and first excited triplet state (T1)

Hiromi Shinohara; Olga Tsaryova; Günter Schnurpfeil; Dieter Wöhrle

2006-01-01

229

Carbon and oxygen net community production in the eastern tropical Atlantic estimated from a moored buoy  

NASA Astrophysics Data System (ADS)

A mooring at 6°S, 10°W has been equipped with an oxygen optode and a Carioca sensor for monitoring hourly oxygen (O2) and the fugacity of CO2 (fCO2) at 1.5 m depth since June 2006. Due to biofouling, the oxygen time series lasted between 72 days in 2008 to 159 days in 2009. Using an alkalinity-salinity relationship determined for the area, dissolved inorganic carbon (DIC) is calculated. Short-term and long-term net community productions (NCP) are calculated using a mass balance approach for DIC and O2 under the assumption of no mixing conditions. The mooring site is always supersaturated in oxygen except in 2007 when depleted oxygen waters are observed from June to September, during the upwelling season. Averaging all the short time events, NCP calculated from the rates of changes of O2 and DIC leads to a NCP of 16.6 ± 6.1 mmol C m-2d-1, ranging from 14.7 mmol C m-2d-1 in 2008 to 17.4 mmol C m-2d-1 in 2006. The mean daily oxygen biological production rate determined over the whole time series shows a significant year to year variability with 7.5 mmol C m-2d-1 in 2008 to 15.6 mmol C m-2d-1 in 2009. A photosynthetic quotient ranging between 1.0 to 1.3 has been determined when both carbon and oxygen NCP values are available.

LefèVre, Nathalie; Merlivat, Liliane

2012-03-01

230

Different doping from apical and planar oxygen vacancies in Ba2CuO4-? and La2CuO4-?: First-principles band structure calculations  

NASA Astrophysics Data System (ADS)

First-principles band structure calculations for large supercells of Ba2CuO4-? and La2CuO4-? with different distributions and concentrations of oxygen vacancies show that the effective doping on copper sites strongly depends on where the vacancy is located. A vacancy within the Cu layer produces a weak doping effect while a vacancy located at an apical oxygen site acts as a stronger electron dopant on the copper layers and gradually brings the electronic structure close to that of La2-xSrxCuO4. These effects are robust and only depend marginally on lattice distortions. Our results show that deoxygenation can reduce the effect of traditional La/Sr or La/Nd substitutions. Our study clearly identifies location of the dopant in the crystal structure as an important factor in doping of the cuprate planes.

Jarlborg, T.; Barbiellini, B.; Markiewicz, R. S.; Bansil, A.

2012-12-01

231

Quaternary ammonium room-temperature ionic liquid including an oxygen atom in side chain/lithium salt binary electrolytes: ab initio molecular orbital calculations of interactions between ions.  

PubMed

Interactions of the lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) complex with N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium (DEME), 1-ethyl-3-methylimidazolium (EMIM) cations, neutral diethylether (DEE), and the DEMETFSA complex were studied by ab initio molecular orbital calculations. An interaction energy potential calculated for the DEME cation with the LiTFSA complex has a minimum when the Li atom has contact with the oxygen atom of DEME cation, while potentials for the EMIM cation with the LiTFSA complex are always repulsive. The MP2/6-311G**//HF/6-311G** level interaction energy calculated for the DEME cation with the LiTFSA complex was -18.4 kcal/mol. The interaction energy for the neutral DEE with the LiTFSA complex was larger (-21.1 kcal/mol). The interaction energy for the DEMETFSA complex with LiTFSA complex is greater (-23.2 kcal/mol). The electrostatic and induction interactions are the major source of the attraction in the two systems. The substantial attraction between the DEME cation and the LiTFSA complex suggests that the interaction between the Li cation and the oxygen atom of DEME cation plays important roles in determining the mobility of the Li cation in DEME-based room temperature ionic liquids. PMID:18636771

Tsuzuki, Seiji; Hayamizu, Kikuko; Seki, Shiro; Ohno, Yasutaka; Kobayashi, Yo; Miyashiro, Hajime

2008-07-18

232

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

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

233

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

NASA Astrophysics Data System (ADS)

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

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

2004-06-01

234

Analytic calculations of ozone concentration in an oxygen-fed wire-to-cylinder ozonizer and comparison with the Vasil'ev relation  

NASA Astrophysics Data System (ADS)

An analytical model for ozone concentration calculations in an oxygen-fed wire-to-cylinder ozonizer is presented in order to improve our basic knowledge on ozone generation. This approach takes into account the physical and chemical phenomena. The Becker parameter is introduced and the ozone concentration deduced from this model is compared to the Vasil'ev relation, the macroscopic coefficients for ozone formation and destruction being expressed as functions of the kinetic coefficients. The general results (electron density, ozone concentration, macroscopic coefficients) are compared with experiments and a good agreement is observed.

Held, B.; Peyrous, R.

1998-10-01

235

Using equilibrium based fugacity analysis to predict site-specific risk based target levels for low permeability soils  

SciTech Connect

This presentation focuses on using fugacity principles to evaluate the impact of petroleum contamination to soil and groundwater in low permeability media. Risk Based Corrective Action (RBCA) regulations have been implemented by many state agencies leading to increased use of various modeling techniques. Infiltration based models are typically used to determine site-specific target levels for soils that ensure groundwater is protective of human health and the environment. Kinetic transport mechanisms (i.e. infiltration) are, however, usually negligible in low permeability soils where vapor-phase diffusion is likely to dominate redistribution of volatile organic compounds (VOCs). Fugacity analysis utilizes thermodynamic equilibrium principles to predict the limits of VOC redistribution to groundwater and nearby soils. This presentation discusses the fugacity analysis and appropriate applications for determining site-specific target levels for site closure. Case studies are also presented showing fugacity analysis achieving site closure when other transport models suggested additional investigation or required remediation.

Hoffman, G.D.; Thompson, C.L.; Sims, R.C.

1996-01-01

236

Supplemental Oxygen (Oxygen Therapy)  

MedlinePLUS

... There are three ways oxygen therapy is supplied: Compressed oxygen gas and liquid oxygen are two ways to have oxygen delivered to the home. Oxygen gas is stored in tanks or cylinders of steel or aluminum. These tanks ...

237

Hydrogen component fugacity in binary mixtures with carbon monoxide: Temperature dependence  

NASA Astrophysics Data System (ADS)

The fugacity coefficients of hydrogen in binary mixtures with carbon monoxide were measured using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane through which hydrogen, but not carbon monoxide, can penetrate. Measurement of the gas pressures inside and outside of the membrane allows a direct measurement of the hydrogen component fugacity at a given temperature and binary mixture mole fraction. In this paper, results are reported at 130, 160, and 190°C. In each case, the total pressure of the mixture was maintained at a nominal value of 3.39 MPa. The general qualitative features of the data are discussed, and comparisons are made with predictions obtained from the Redlich-Kwong, Peng-Robinson-Soave, and extended corresponding-state models.

Bruno, T. J.; Schroeder, J. A.

1988-07-01

238

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

NASA Astrophysics Data System (ADS)

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

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

1990-09-01

239

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

NASA Astrophysics Data System (ADS)

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

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

1990-01-01

240

Hydrogen component fugacity in binary mixtures with carbon monoxide: temperature dependence  

SciTech Connect

The fugacity coefficients of hydrogen in binary mixtures with carbon monoxide were measured using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane through which hydrogen, but not carbon monoxide, can penetrate. Measurement of the gas pressures inside and outside of the membrane allows a direct measurement of the hydrogen component fugacity at a given temperature and binary mixture mole fraction. In this paper, results are reported at 130, 160, and 190/sup 0/C. In each case, the total pressure of the mixture was maintained at a nominal value of 3.39 MPa. The general qualitative features of the data are discussed, and comparisons are made with predictions obtained from the Redlich-Kwong, Peng-Robinson-Soave, and extended corresponding-state models.

Bruno, T.J.; Schroeder, J.A.

1988-07-01

241

Stability of oxygen point defects in UO2 by first-principles DFT+U calculations: Occupation matrix control and Jahn-Teller distortion  

NASA Astrophysics Data System (ADS)

Point-defect formation energies in uranium dioxide UO2 are still a matter of debate due to the significant discrepancies between the various studies published in the literature. These discrepancies stem from the density functional theory (DFT)+U approximation that creates multiple energy minima and complexifies the search for the ground state. We report here DFT+U values of the formation energies for the single oxygen interstitial and vacancy in UO2 , both in the fluorite and the Jahn-Teller distorted structures, using a scheme developed on bulk UO2 [B. Dorado, B. Amadon, M. Freyss, and M. Bertolus, Phys. Rev. B 79, 235125 (2009)10.1103/PhysRevB.79.235125] and based on occupation matrix control. We first investigate the Jahn-Teller distortion in UO2 in the noncollinear antiferromagnetic order and we show that the distortion stabilizes the system by 50meV/UO2 compared to the fluorite structure. Moreover, it is found that the oxygen atoms are displaced in the ?111? directions, in agreement with experiments. For the bulk fluorite structure, we show that the use of the Dudarev approach of the DFT+U without occupation matrix control systematically yields the first metastable state, located 45meV/UO2 above the ground state. As a result, all previously published point-defect formation energies are largely underestimated. We then use the occupation matrix control scheme to calculate the formation energies of the single oxygen interstitial and vacancy in UO2 . We confirm that this scheme always allows one to reach the lowest energy states and therefore yields reliable formation energies. Finally, we compare our values with those obtained in previous studies and show that the discrepancies observed stem from the calculations of defective supercells which have reached different metastable states.

Dorado, Boris; Jomard, Gérald; Freyss, Michel; Bertolus, Marjorie

2010-07-01

242

Hydrothermal Stability of Adenine Under Controlled Fugacities of N 2 , CO 2 and H 2  

Microsoft Academic Search

An experimental study has been carried out on the stability of adenine (one of the five nucleic acid bases) under hydrothermal\\u000a conditions. The experiments were performed in sealed autoclaves at 300°C under fugacities of CO2, N2 and H2 supposedly representative of those in marine hydrothermal systems on the early Earth. The composition of the gas phase was\\u000a obtained from the

Michael Franiatte; Laurent Richard; Marcel Elie; Chinh Nguyen-Trung; Erwan Perfetti; Douglas E. LaRowe

2008-01-01

243

Comparison of multi-media transport and transformation models: Regional Fugacity model vs. CalTOX  

Microsoft Academic Search

Two multimedia environmental transport and transformation computer models are summarized and compared. The regional fugacity model published by Mackay and Paterson (1991), termed Fug3ONT, is a four compartment steady-state model designed to simulate the relative distribution of nonionic organic chemicals in a multimedia system. CalTOX is a seven compartment multimedia total exposure model for hazardous waste sites. Both models are

Randy L. Maddalena; Thomas E. McKone; David W. Layton; Dennis P. H. Hsieh

1995-01-01

244

Simulation of the fate and seasonal variations of ?-hexachlorocyclohexane in Lake Chaohu using a dynamic fugacity model.  

PubMed

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

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

2012-12-18

245

Embedded Green-function calculation of the conductance of oxygen-incorporated Au and Ag monatomic wires  

NASA Astrophysics Data System (ADS)

We investigate the electronic structure and ballistic conductance of O-incorporated noble-metal atomic wires by a first-principles calculation using the embedded Green-function technique and the full-potential linearized augmented plane wave method. We consider straight monatomic wires with a single O atom inserted between two metal atoms. It will be shown that the conductance of the Au 6s (Ag 5s ) channel is reduced significantly by electron scattering via the inserted O atom. On the other hand, the O 2px,y (?) states, which form a resonant peak near the Fermi level EF , provide two additional conduction channels in a narrow energy range corresponding to the resonant peak. Since the dxz,yz components of neighboring metal atoms, which hybridize with the O 2px,y orbitals and mediate coupling between them and the energy continuum in the leads, decay exponentially with distance from the O atom, the width of the resonance as well as the conductance associated with these two states decreases with increasing wire length. For longer wires, the wire undergoes a transition to a spin-polarized state with the O 2px,y resonance splitting into a fully occupied majority-spin peak and a partially occupied minority-spin peak. The latter contributes to a partially spin-polarized conductance at EF .

Ishida, H.

2007-05-01

246

Oxygen and silicon partitioning between molten iron and silicate melts  

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

247

Oxygen diffusion in magnetite  

NASA Astrophysics Data System (ADS)

The diffusion rate of oxygen in magnetite (Fe3O4) has been measured under hydrothermal conditions between 800° and 500°C at 1000 bars pressure, and yields the Arrhenius relation: D = 3.5 × 10-6 exp(-45,000/RT) kcal/g-atom O. The diffusion rate was found to be the same, within the estimated uncertainty of a factor of 2, for measurements at 100, 1000, and 2000 bars (20-200 MPa) water pressure, and for oxygen fugacities buffered by magnetite-hematite and approximately Ni-NiO. The activation energy and diffusion mechanism probably change to that given by Castle and Surman [10] at temperatures below 460°C. The oxygen diffusion rate in magnetite is between those of quartz and hornblende. Closure temperatures fall in the range 380°C for 0.1 mm radius grains cooling at 1°C/m.y. to 675°C for 1 mm radius and cooling at 1000°C/m.y. if the present data are used, but will be lower for the fine grain sizes and slow cooling rates if the Castle and Surman data are used.

Giletti, B. J.; Hess, K. C.

1988-06-01

248

Overlooked difference between hydrogen bonds of equal strength formed between catechol and an oxygen or nitrogen base. Experiments and DFT calculations.  

PubMed

The IR spectrum of catechol in CCl(4) shows two fairly sharp O-H stretching bands of roughly equal absorbance at 3615.0 and 3569.6 cm(-1) due, respectively, to the "free" OH and the intramolecularly H-bonded OH groups. Intermolecular H-bond formation between the "free" OH and a hydrogen bond acceptor (HBA) decreases its stretching frequency by several hundred wavenumbers and simultaneously decreases the frequency of the intramolecularly H-bonded OH by a few tens of wavenumbers. The magnitude of these frequency shifts, Deltaupsilon(inter) and Deltaupsilon(intra), respectively, are very well reproduced by DFT calculations. As would be expected, the magnitudes of Deltaupsilon(inter) and Deltaupsilon(intra) increase as the HB accepting ability of the HBA increases as quantified, on a relative scale, by the HBA's values (Abraham et al. J. Chem. Soc. Perkin Trans. 2 1990, 521). However, plots of experimental, or calculated, frequency shifts versus reveal that Deltaupsilon(inter) and Deltaupsilon(intra) are ca. 40% larger for a nitrogen atom HBA than for an oxygen atom HBA having equal HBA activity. We hypothesize that for HBAs of equal strength, i.e., of equal, the H-bond in (O-H- - -O)(inter) is shorter and, hence, intrinsically stronger than the H-bond in the (O-H- - -N)(inter). However, we further hypothesize that there is more charge separation in the H-bond to N because N is a better proton acceptor than O. Hence, it is the greater Coulombic attraction in (O-H- - -N)(inter) which strengthens this H-bond and compensates for its greater length. Theoretical calculations lend support to these hypotheses. PMID:14624616

Foti, Mario C; DiLabio, Gino A; Ingold, K U

2003-11-26

249

Significance of M.I. Temkin`s concept of a fugacity of adsorbed substances for the progress in studies on the kinetics and mechanism of catalytic reactions  

SciTech Connect

The concept of a fugacity (virtual pressure) of adsorbed substances is considered. The application of this concept is demonstrated by a series of examples. The notion of a fugacity of adsorbed substances is used for the explanation of the selectivity in catalysis.

Krylov, O.V. [Semenov Institute of Chemical Physics, Moscow (Russian Federation)

1995-01-01

250

Hydrogen component fugacities in binary mixtures with carbon dioxide: Pressure dependence  

NASA Astrophysics Data System (ADS)

The fugacity coefficients of hydrogen in binary mixtures with carbon dioxide were measured isothermally using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane. Hydrogen can penetrate and pass through the membrane, while carbon dioxide cannot. During the approach to equilibrium, the pressure of pure hydrogen on one side of the membrane approaches the partial pressure of hydrogen in the mixture on the other side of the membrane. This allows a direct measurement of the hydrogen component fugacity at a given mixture mole fraction. In this study, results are reported for measurements made on the hydrogen + carbon dioxide binary at 130°C (403 K), with total mixture pressure of 3.45, 5.17, 8.62, 10.34, and 13.79 MPa. General trends in the experimental results are discussed, and comparisons are made with predictions from the Redlich-Kwong, Peng-Robinson, and extended corresponding-states models.

Bruno, T. J.

1987-03-01

251

Hydrogen component fugacities in binary mixtures with carbon dioxide: pressure dependence  

SciTech Connect

The fugacity coefficients of hydrogen in binary mixtures with carbon dioxide were measured isothermally using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane. Hydrogen can penetrate and pass through the membrane, while carbon dioxide cannot. During the approach to equilibrium, the pressure of pure hydrogen on one side of the membrane approaches the partial pressure of hydrogen in the mixture on the other side of the membrane. This allows a direct measurement of the hydrogen component fugacity at a given mixture mole fraction. In this study, results are reported for measurements made on the hydrogen + carbon dioxide binary at 130/sup 0/C (403 K), with total mixture pressure of 3.45, 5.17, 8.62, 10.34, and 13.79 MPa. General trends in the experimental results are discussed, and comparison are made with predictions from the Redlich-Kwong, Peng-Robinson, and extended corresponding-states models.

Bruno, T.J.

1987-03-01

252

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

253

A fugacity based continuous and dynamic fate and transport model for river networks and its application to Altamaha River.  

PubMed

In this paper, a continuous and dynamic fugacity-based contaminant fate and transport model is developed. The dynamic interactions among all phases in the physical domain are addressed through the use of the fugacity approach instead of the use of concentration as the unknown variable. The full form of Saint Venant equations is used in order to solve for the hydrodynamic conditions in the river network. Then a fugacity-based advection-dispersion equation is modeled to examine the fate and transport of contaminants in the river network for all phases. The fugacity-based, dynamic and continuous contaminant fate and transport model developed here is applied to Altamaha River in Georgia, USA to demonstrate its use in environmental exposure analysis. Altamaha River is the largest river system east of Mississippi which offers habitat for many species, including about 100 rare endangered species, along its 140 mile course. Polychlorinated biphenyls (PCBs), a highly hydrophobic and toxic chemical ubiquitous in nature, and atrazine, the most commonly-used agricultural pesticide are modeled as contaminants in this demonstration. Through this approach the concentration distribution of PCBs and atrazine in the water column of Altamaha River as well as the sediments can be obtained with relative ease, which is an improvement over concentration based analysis of phase distribution of contaminants. PMID:19321188

Kilic, Sinem Gokgoz; Aral, Mustafa M

2009-03-25

254

Iron and zinc partitioning between coexisting stannite and sphalerite: a possible indicator of temperature and sulfur fugacity  

Microsoft Academic Search

Stannite and sphalerite coexisting with iron sulfides (pyrite and\\/or pyrrhotite) from Japanese ore deposits associated with tin mineralization were analyzed. Based on the iron and zinc partitioning between stannite and sphalerite, the formation temperature and sulfur fugacity for this mineral assemblage were estimated. A good correlation between stannite-sphalerite temperatures and filling temperatures of fluid inclusions and sulfur isotope temperatures was

M. Shimizu; N. Shikazono

1985-01-01

255

Thermodynamics of Si(OH) 4 in the vapor phase of water: Henry's and vapor-liquid distribution constants, fugacity and cross virial coefficients  

NASA Astrophysics Data System (ADS)

The fugacity coefficients of Si(OH) 4 are evaluated from solubilities of solid phases of SiO 2 in the vapor phase of water. The virial equation of state, truncated at the third virial coefficient, is employed to describe the fugacity coefficients of Si(OH) 4. The temperature dependencies of the second, B12, and the third, C112, cross virial coefficients for H 2O-Si(OH) 4 interactions are approximated by empirical relations. It is found that silica-water interactions in the vapor phase are significantly more non-ideal compared to water-water interactions. Knowledge of B12 and C112 allows calculation of solubilities of quartz (Q) and amorphous silica (AS) in steam up to the density of 200 kg m -3 in satisfactory agreement with available data, and should provide reasonable solubility values at temperatures where no experimental results exist. The calculated values of the solubility of Q and AS in saturated vapor up to the critical temperature of water, Tc, are tabulated. The partial molar properties of dilute solutes close to the critical point of water are governed by the Krichevskii parameter, the value of which for Si(OH) 4 is evaluated from available data (mainly vapor-liquid distribution constants for silica) to be equal to -187 ± 10 MPa. The knowledge of the thermodynamic properties of Si(OH) 4 in the ideal gas state and in the state of the standard solution in liquid water allows calculating Henry's constant, kH, for Si(OH) 4 up to 623.15 K at water saturation pressure P1?. The theoretically-based equation, containing the Krichevskii parameter, allows extrapolating kH values all the way toward the critical temperature of water. This, in turn, makes possible calculation of the solubility of quartz and amorphous silica in liquid water at P1? at all temperatures up to Tc. The presented results should be useful for modeling solid-liquid-vapor, solid-vapor and liquid-vapor equilibria in the H 2O-SiO 2 system at steam densities up to 200 kg m -3.

Plyasunov, Andrey V.

2012-01-01

256

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

PubMed

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

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

2009-06-23

257

Trihalomethane exposures in indoor swimming pools: a level III fugacity model.  

PubMed

The potential for generation of disinfection byproducts (DBPs) in swimming pools is high due to the concentrations of chlorine required to maintain adequate disinfection, and the presence of organics introduced by the swimmers. Health Canada set guidelines for trihalomethanes (THMs) in drinking water; however, no such guideline exists for swimming pool waters. Exposure occurs through ingestion, inhalation and dermal contact in swimming pools. In this research, a multimedia model is developed to evaluate exposure concentrations of THMs in the air and water of an indoor swimming pool. THM water concentration data were obtained from 15 indoor swimming pool facilities in Quebec (Canada). A level III fugacity model is used to estimate inhalation, dermal contact and ingestion exposure doses. The results of the proposed model will be useful to perform a human health risk assessment and develop risk management strategies including developing health-based guidelines for disinfection practices and the design of ventilation system for indoor swimming pools. PMID:21816450

Dyck, Roberta; Sadiq, Rehan; Rodriguez, Manuel J; Simard, Sabrina; Tardif, Robert

2011-07-13

258

Error propagation in fugacity level-III models in the case of uncertain physicochemical compound properties  

SciTech Connect

For a level-III fugacity model to predict the steady-state environmental distribution of chemicals on a regional scale, the effect of erroneous physicochemical input data on the model output was studied using Monte Carlo simulations. Uncertainty analyses were performed for the octanol/water partition coefficient and Henry`s law constant with assumed standard errors of 0.5 and 0.1 log units according to corresponding Gauss distributions, using phenol, pentachlorophenol, ethanol, acetone, and anthracene as model compounds. The results showed considerable variations of factors up to 2.5 for the predicted relative distributions among the major compartments. The output variations were greater for compounds with more than one sink. The results demonstrate the need for addressing error propagation in multimedia models in a systematic way.

Kuehne, R.; Breitkopf, C.; Schueuermann, G. [UFZ Centre for Environmental Research. Leipzig (Germany). Dept. of Chemical Ecotoxicology

1997-10-01

259

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

SciTech Connect

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.

McKone, T.E.

1990-10-01

260

The Gibbs free energy of mixing of natural silicate liquids; an expanded regular solution approximation for the calculation of magmatic intensive variables  

Microsoft Academic Search

The compositions of liquids coexisting with experimentally grown crystals of olivine, plagioclase, clinopyroxene, orthopyroxene, leucite, spinel, rhombohedral oxide, melilite and potassium feldspar are used to define, through mass action expressions of liquid\\/solid equilibrium, compositional derivatives of the Gibbs free energy of mixing of naturally occuring silicate liquids as a function of temperature, pressure and the fugacity of oxygen. The available

Mark S. Ghiorso; Ian S. E. Carmichael; Mark L. Rivers; Richard O. Sack

1983-01-01

261

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

Microsoft Academic Search

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

A. Holzheid; A. Borisov; H. Palme

1994-01-01

262

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

National Technical Information Service (NTIS)

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 ...

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

2013-01-01

263

Experimental investigation of the influence of oxygen fugacity on the source depths for high titanium lunar ultramafic magmas  

NASA Astrophysics Data System (ADS)

High pressure and high temperature experiments were carried out on two pristine ultramafic high titanium glass compositions from the Moon. The investigated compositions are the Apollo 15 red glass (13.8 wt% TiO2) and Apollo 17 orange glass (9.1 wt% TiO2). Temperatures spanned the range of 1320-1570 °C, and pressures 0.8-3.3 GPa. Graphite and iron metal capsules were used to control f at iron-wüstite (?IW) + 1.3 log units to ?IW-2.1, respectively. Multiple saturation with olivine and orthopyroxene on the liquidus occurs at 1.2 GPa and 1350 °C for the red glass, and 2.5 GPa and 1530 °C for the orange glass in graphite capsules. In Fe capsules the multiple saturation points (MSP) shift to higher pressure, and are 2.2 GPa and 1450 °C for the red glass, and 3.1 GPa and 1560 °C for the orange glass. The magnitude of the shift in MSP increases with increasing TiO2 content. The changes in MSP are caused by f and correspond to a ˜200 km shift in the estimated minimum depth of origin for the red glass, and up to a 300 km range in depth between the red and orange glass depth of origin. Using independent estimates of f for the orange glass source region of ?IW-0.6 (Sato, 1979; Nicholis and Rutherford, 2009), interpolation of our phase stability data yields a pressure of multiple saturation of 2.8 GPa. Our results confirm that the red and orange glasses are buoyant with respect to model lunar interior assemblages at their multiple saturation pressures. The difference in the pressure of liquidus multi-phase saturation is possibly due to a shift in the Ti-Fe coordination in high-Ti melts. Evidence for this coordination change comes from systematic changes in olivine-melt Fe-Mg KD's with f, pressure, temperature, and TiO2 content.

Krawczynski, Michael J.; Grove, Timothy L.

2012-02-01

264

Upper mantle oxidation state: Ferric iron contents of Iherzolite spinels by 57 Fe Mössbauer spectroscopy and resultant oxygen fugacities  

Microsoft Academic Search

The ferric iron contents of spinels from 30 spinel Iherzolite xenoliths have been measured by 57 Fe Mössbauer spectroscopy. The samples are widely dispersed in geographic and tectonic setting, coming from Southwest United States (San Carlos, Kilbourne Hole), Japan (Ichinomegata), Massif Central, France (Mont Briançon) and Central Asia (Tariat Depression, Vitim Plateau). The total range of Fe 3 O 4

Bernard J. Wood; David Virgo

1989-01-01

265

Simultaneous spectrophotometric flow-through measurements of pH, carbon dioxide fugacity, and total inorganic carbon in seawater  

Microsoft Academic Search

An autonomous multi-parameter flow-through CO2 system has been developed to simultaneously measure surface seawater pH, carbon dioxide fugacity (fCO2), and total dissolved inorganic carbon (DIC). All three measurements are based on spectrophotometric determinations of solution pH at multiple wavelengths using sulfonephthalein indicators. The pH optical cell is machined from a PEEK polymer rod bearing a bore-hole with an optical pathlength

Zhaohui Aleck Wang; Xuewu Liu; Robert H. Byrne; Rik Wanninkhof; Renate E. Bernstein; Eric A. Kaltenbacher; James Patten

2007-01-01

266

Probabilistic application of a fugacity model to predict triclosan fate during wastewater treatment.  

PubMed

The fate and partitioning of the antimicrobial compound, triclosan, in wastewater treatment plants (WWTPs) is evaluated using a probabilistic fugacity model to predict the range of triclosan concentrations in effluent and secondary biosolids. The WWTP model predicts 84% to 92% triclosan removal, which is within the range of measured removal efficiencies (typically 70% to 98%). Triclosan is predominantly removed by sorption and subsequent settling of organic particulates during primary treatment and by aerobic biodegradation during secondary treatment. Median modeled removal efficiency due to sorption is 40% for all treatment phases and 31% in the primary treatment phase. Median modeled removal efficiency due to biodegradation is 48% for all treatment phases and 44% in the secondary treatment phase. Important factors contributing to variation in predicted triclosan concentrations in effluent and biosolids include influent concentrations, solids concentrations in settling tanks, and factors related to solids retention time. Measured triclosan concentrations in biosolids and non-United States (US) effluent are consistent with model predictions. However, median concentrations in US effluent are over-predicted with this model, suggesting that differences in some aspect of treatment practices not incorporated in the model (e.g., disinfection methods) may affect triclosan removal from effluent. Model applications include predicting changes in environmental loadings associated with new triclosan applications and supporting risk analyses for biosolids-amended land and effluent receiving waters. PMID:20821703

Bock, Michael; Lyndall, Jennifer; Barber, Timothy; Fuchsman, Phyllis; Perruchon, Elyse; Capdevielle, Marie

2010-07-01

267

Erratum: Probabilistic application of a fugacity model to predict triclosan fate during wastewater treatment.  

PubMed

The fate and partitioning of the antimicrobial compound, triclosan, in wastewater treatment plants (WWTPs) is evaluated using a probabilistic fugacity model to predict the range of triclosan concentrations in effluent and secondary biosolids. The WWTP model predicts 84% to 92% triclosan removal, which is within the range of measured removal efficiencies (typically 70% to 98%). Triclosan is predominantly removed by sorption and subsequent settling of organic particulates during primary treatment and by aerobic biodegradation during secondary treatment. Median modeled removal efficiency due to sorption is 40% for all treatment phases and 31% in the primary treatment phase. Median modeled removal efficiency due to biodegradation is 48% for all treatment phases and 44% in the secondary treatment phase. Important factors contributing to variation in predicted triclosan concentrations in effluent and biosolids include influent concentrations, solids concentrations in settling tanks, and factors related to solids retention time. Measured triclosan concentrations in biosolids and non-United States (US) effluent are consistent with model predictions. However, median concentrations in US effluent are over-predicted with this model, suggesting that differences in some aspect of treatment practices not incorporated in the model (e.g., disinfection methods) may affect triclosan removal from effluent. Model applications include predicting changes in environmental loadings associated with new triclosan applications and supporting risk analyses for biosolids-amended land and effluent receiving waters. PMID:20824886

Bock, Michael; Lyndall, Jennifer; Barber, Timothy; Fuchsman, Phyllis; Perruchon, Elyse; Capdevielle, Marie

2010-10-01

268

Experimental measurements of the fugacity of C0 2 and graphite/diamond stability from 35 to 77 kbar at 925 to 1650°C  

NASA Astrophysics Data System (ADS)

The f O2 of the equilibrium between graphite and C-O fluid has been determined at 35-77 kbar and 925-1650°C using metal-metal oxide reactions as redox sensors and by employing an assemblage of Co-Pd alloy and CoO as a sliding redox sensor. In the latter case, the equilibrium composition of the Co-Pd alloy was approached from two starting compositions of initially higher and lower Co contents. The measurements translate into measurements of the fugacity of CO 2 with uncertainties in the range 0.13-0.20 log units. Our determinations of f CO2 show reasonable, but not perfect agreement, with the equations of state of Saxena and Fei (1987) and Sterner and Pitzer (1994). Modified forms of the Redlich-Kwong equation of state ( Holloway, 1977; Flowers, 1979; Kerrick and Jacobs, 1981) predict values of f CO2 that, in some parts of P, T space, are over 1 log unit higher than those determined experimentally. An equation of state for CO 2 has been parameterised using our new measurements and existing low pressure data ( Kennedy and Holser, 1966; Shmonov and Shmulovich, 1974). The equation of state is suitable for the calculation of CO 2 properties in the range 1 bar to 77 kbar and 925-1650°C.

Frost, Daniel J.; Wood, Bernard J.

1997-04-01

269

Finite element multiconfiguration Hartree-Fock calculations on carbon, oxygen, and neon: The nuclear quadrupole moments of {sup 11}C, {sup 17}O, and {sup 21}Ne  

SciTech Connect

The authors report new calculations for the nuclear quadrupole moments of {sup 11}C, {sup 17}O, and {sup 21}Ne, making use of a new finite-element multiconfiguration Hartree-Fock method. They calculate electric field gradients at the nuclei and combine these with measurements of nuclear quadrupole coupling constants to arrive at the values.

Sundholm, D. [Univ. of Helsinki (Finland); Olsen J. [Univ. of Lund (Sweden)

1992-01-23

270

Vanadium K-Edge XANES and its Application to Microscale Oxygen Barometry  

NASA Astrophysics Data System (ADS)

A promising proxy for oxygen fugacity is the valence of vanadium because it has a large number of possible states (2+, 3+, 4+ and 5+) and is ubiquitous in earth and planetary materials. A non-destructive method for valence determinations of vanadium and oxygen fugacity estimates with spatial resolution of a few micrometers is synchrotron x-ray absorption near edge structure (XANES) spectroscopy. The valence determination is based on the intensity of a pre-edge peak near 5470 eV in the vanadium K-edge XANES spectrum and much of our development work has focused on igneous glasses. A key to this method is calibration with standards of known valence and experimental charges produced under known conditions. Vanadium pre-edge peak intensity correlates well with the known valence states for glasses whose valence was established independently. Using this calibration curve, the effective valences of other glasses can be determined. Measurements on isobaric experimental couples were used to determine the magnitude of valence variations due to temperature differences. In this way, a calibration curve for peak intensity versus oxygen fugacity can be produced for the appropriate liquidus temperature of each unknown glass. The method has been successfully applied to natural glasses from the Earth, Moon and Mars.

Sutton, S. R.; Karner, J. M.; Papike, J. J.; Delaney, J. S.; Shearer, C. K.; Newville, M. G.

2005-12-01

271

Exploring haem-based alternatives for oxygen reduction catalysis in fuel cells—a status report of our first principles calculations  

NASA Astrophysics Data System (ADS)

For hydrogen fuel cells to become commercially viable, an alternative catalyst to platinum surfaces that is both efficient and affordable must be discovered. We consider haem and haem derivatives as potentials substitutes. In this paper, we discuss the oxygen reduction reaction on both the platinum surface and on haem. We then introduce our suggestions based on density-functional studies on how to improve haem's oxygen-reduction capabilities, which can be summarized as follows: inducing the singlet state, inducing side-on interaction, mimicking cytochrome c oxidase by adding a copper-imidazole complex, using platinum deposited on tin porphyrin instead of haem, and using oxomolybdenum porphyrin instead of haem. We shall focus on the last three methods because of their experimental practicability.

Dy, E. S.; Roman, T. A.; Kubota, Y.; Miyamoto, K.; Kasai, H.

2007-11-01

272

Development of a soil fugacity sampler for determination of air-soil partitioning of persistent organic pollutants under field controlled conditions.  

PubMed

Soils are the main reservoir of persistent organic pollutants (POPs) and thus air-soil exchange and partitioning are key processes controlling the fate and transport of POPs at regional and global scales. To date, soil fugacity has been estimated from models of the soil-air partition coefficients, with the associated unavoidable uncertainties; or by experimental procedures in the laboratory with uncertain application in field conditions. The development of an operational soil fugacity sampler is presented here; one which ensures optimal field data of the POP fugacity in soil and environmentally relevant surface (soil+grass, etc.) and therefore ensuring accurate soil-air partition coefficients and surface-air fugacity gradients. The sampler flow rate is optimized, sampler reproducibility is assessed, and equilibrium between the gas and soil concentrations of polychlorinated biphenyls and polycyclic aromatic hydrocarbons is demonstrated. The development and comprehensive validation of a soil fugacity sampler opens the door for the first time to field studies that accurately determine the variables driving the soil-air partitioning and fluxes of POPs. PMID:19924953

Cabrerizo, Ana; Dachs, Jordi; Barceló, Damià

2009-11-01

273

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

PubMed Central

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.

Dick, Jeffrey M

2008-01-01

274

Precipitates/Salts Model Sensitivity Calculation  

SciTech Connect

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.

P. Mariner

2001-12-20

275

Effects of hydrogen fugacity and confining pressure on the interdiffusion rate of NaSi-CaAl in plagioclase  

NASA Astrophysics Data System (ADS)

Average? values for NaSi-CaAl interdiffusion in the compositional interval from An0 to An26 have been determined at 1000°C by the method of lamellar homogenization. At 1500 MPa confining pressure (P), ? increases 1 order of magnitude (5.0×10-21 to 4.0×10-20 m2/s) for 4 orders of magnitude increase in hydrogen fugacity (0.029, Mn3O4-Mn2O3 buffer, to 197 MPa, FeO-Fe3O4 buffer). At constant hydrogen fugacity (fH2), ? increases rapidly at low pressure and becomes nearly independent of P above 1000 MPa. (For fH2 = 0.1 MPa, ? = 2.8 × 10-22 m2/s at P = 0.1 MPa, 5.0 × 10-21 at P = 500, 1.3×10-20 at P = 1000, and 1.4×10-20 at P = 1500). The dependence of ? on increasing pressure, when a hydrogen-related species is present, is believed to be due to an increase in the concentration of the structural defect associated with increase in the hydrogen impurity. In most crustal igneous rocks, which are internally buffered near quartz-fayalite-magnetite, the dependence of ? on fH2 is relatively minor compared to the effect of confining pressure.

Yund, Richard A.; Snow, Eleanour

1989-08-01

276

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

Microsoft Academic Search

The five solid-phase oxygen buffers of the system Fe-Si-O, iron-wuestite (IW), wuestite-magnetite (WM), magnetite-hematite (MH), quartz-iron-fayalite (QIF) and fayalite-magnetite-quartz (FMQ) have been recalibrated at 1 atm pressure and temperatures from 800°–1,300° C, using a thermogravimetric gas mixing furnace. The oxygen fugacity, \\u000a$$f_{{\\\\text{O}}_{\\\\text{2}} }$$\\u000a was measured with a CaO-doped ZrO2 electrode. Measurements were made also for wuestite solid solutions in order

J. Myers; H. P. Eugster

1983-01-01

277

SIGMELTS: A Web-portal for Electrical Conductivity Calculations in Geosciences  

NASA Astrophysics Data System (ADS)

We present a freely available and easy-to-use web application called SIGMELTS allowing the calculation of the electrical conductivity of geomaterials at relevant conditions for the Earth’s crust and mantle. By compiling previous results of electrical measurements in laboratory, this software enables to discriminate between the effect of different parameters on the bulk conductivity of silicate melts, carbonatites, fluids, minerals and mantle materials, such as the temperature (T), the pressure (P), the composition, the water content, the oxygen fugacity (fO2) and the crystal content. Different existing geometrical models are proposed to calculate the bulk conductivity of a two-phase mixture. Based on the electrical conductivity value of a mantle anomaly, an application has also been developed to determine the corresponding melt fraction at defined conditions (T, P, composition). This web application aims at improving the accessibility to laboratory data in order to precise the interpretation of MT profiles. Although there are examples of where the laboratory data have been used to interpret field data, there are also many instances where there are disconnects between those interpreting field MT data and the laboratory results. SIGMELTS also underlines that new electrical measurements in laboratory are needed to enlarge the present electrical database, particularly at high pressure conditions. An illustration of the use of SIGMELTS will be presented, in which calculations are applied to subduction zone related volcanic zone in the Central Andes. Along with petrological considerations, field and laboratory electrical data allow discrimination between the different hypotheses regarding the formation and rise from depth of melts and fluids and to quantify their storage conditions.

Le Trong, E.; Pommier, A.

2010-12-01

278

Thermodynamic properties of oxygen  

NASA Astrophysics Data System (ADS)

This volume incorporates current information about the density and isochoric specific heat of oxygen into a reliable set of tables. Temperatures and pressures covered range from the triple point to 1500 K and 0.1 to 1900 MPa. The information describes oxygen in both the liquid and gaseous phases. A unified equation of state is presented and discussed, and the method used to calculate the tables is described.

Sychev, Viacheslav Vladimirovich; Vasserman, A. A.; Kozlov, A. D.; Spiridonov, G. A.; Tsymarnyi, V. A.

279

Oxygen Therapy  

MedlinePLUS

... not smoke near oxygen, or keep oxygen near open flames, or other sources of heat or flames Doctor’s Office Telephone: Your healthcare provider has prescribed oxygen therapy for your lung condition The ATS Patient Information Series is a public service ...

280

Oxygen stoichiometry, structural transitions, and thermodynamic behavior of the YBa sub 2 Cu sub 3 O sub x system  

SciTech Connect

Electromotive force (EMF) measurements of oxygen fugacities as a function of oxygen stoichiometry in the YBa{sub 2}Cu{sub 3}O{sub x} system (1-2-3 superconductor) have been carried out over the composition range x {approx equal} 6.15 to 6.9 and the temperature range 400--750{degree}C. A coulometric titration technique with an yttria-doped zirconia electrolyte was used for these measurements. By means of this technique, the oxygen content of the superconductor is varied by well-defined small amounts, and the equilibrium oxygen partial pressures can be established from the EMF measurements. The overall objective of these studies is to investigate the phase transformations and thermodynamic behavior of the YBa{sub 2}Cu{sub 3}O{sub x} system as a function of oxygen partial pressure, oxygen stoichiometry, and temperature. 24 refs., 8 figs.

Tetenbaum, M.; Curtiss, L.A.; Tani, B.; Czech, B.; Blander, M. (Argonne National Lab., IL (USA))

1989-01-01

281

Insights into oxygen-cation bonding in fresnoite-type structures from O K- and Ti L23-electron energy-loss spectra and ab initio calculations of the electronic structure  

NASA Astrophysics Data System (ADS)

O K- and Ti L23-core-loss spectra of fresnoite Ba2TiSi2O8 (BTS) and Sr2TiSi2O8 (STS), which is isotypic to BTS, have been measured by electron energy-loss spectroscopy (EELS). The energy-loss near-edge structures (ELNES) of the O K edge have been identified on the basis of theoretical simulations and interpretations of the X-ray absorption near-edge structures (XANES), which have been modelled in the framework of self-consistent full multiple-scattering (FMS) theory using FEFF8. Herewith, the K-absorption spectra of oxygen ?(E) and the local partial electron density of states (DOS) of all atoms have been calculated. For BTS, the observed spectral features in the O K-edge spectra are interpreted in terms of mixing between the central O p and neighbouring Ba 5d and 4f, Si 3p and 3d, and Ti 3d orbitals. The observed differences in the O K-edge spectra for STS and BTS can mainly be attributed to three properties: (1) The lack of high local partial Sr unoccupied DOS with 4f symmetry near the Fermi level compared to the high Ba 4f unoccupied DOS results in differences of overlapping O 2p cation orbitals. (2) The differences in the ionic radii of Sr and Ba result in a larger unit cell for BTS and, thus, in larger oxygen-cation bonding distances. (3) In comparison to STS, the strength of the incommensurate 2-D structural modulation is significantly weaker in BTS, i.e. distortions of coordination polyhedra occur to a much lesser extent. All these effects alter the oxygen-cation hybridization and, hence, result in a variation of the O 1s ? p transition and consequently of the O K-edge spectral shape. The observed peak broadening in Ti L23 ELNES of STS compared to BTS is correlated with strong displacive modulations hosted in STS.

van Aken, P. A.; Höche, T.; Heyroth, F.; Keding, R.; Uecker, R.

2004-10-01

282

An empirical model for the calculation of spinel-melt equilibria in mafic igneous systems at atmospheric pressure: 2. Fe-Ti oxides  

Microsoft Academic Search

In order to develop models simulating the crystallization of Fe-Ti oxides in natural lavas, we have processed published experimental\\u000a data on magnetite-melt and ilmenite-melt equilibria. These data include 62 Mt-melt and 75 Ilm-melt pairs at temperatures 1040–1150?°C, oxygen fugacities from IW to NNO+2, and bulk compositions ranging from ferrobasalts to andesites and dacites. Five major cations (Fe3+, Fe2+, Ti4+, Mg2+

Alexi A. Ariskin; Galina S. Barmina

1999-01-01

283

Enhancement and suppression of the transition temperature of a three-dimensional XY ferromagnet by control of vortex-loop fugacity  

SciTech Connect

A previous vortex-loop scaling analysis for the three-dimensional {ital XY} model is extended to include an external loop-segment chemical potential {mu}={lambda}{ital k}{sub {ital B}}{ital T}. The loop fugacity {ital y}{sub 0} is suppressed, {ital y}{sub 0}{r arrow}{ital y}{sub 0}{ital e}{sup {minus}2{pi}{lambda}}, for {lambda}{gt}0, enhancing the transition temperature {ital T}{sub {ital c}}({lambda}), in agreement with the Monte Carlo work of Kohring, Shrock, and Wills. One also gets the suppression of transition temperatures {Tc}({ital e}{sup 2}) of lattice superconductors by electromagnetic charge {ital e}{sup 2}, by mapping onto this loop-fugacity model. A possible approach to superconductor high-{Tc} enhancement, by tailored suppression of topological excitations, is briefly conjectured.

Shenoy, S.R. (School of Phyics, University of Hyderabad, Hyderabad 500134, Andhra Pradesh (India))

1990-11-01

284

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

Microsoft Academic Search

Surface seawater fugacity of carbon dioxide (fCO2) 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

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

2006-01-01

285

Solubility of gases in liquids. 18. High-precision determination of Henry fugacities for argon in liquid water at 2 to 40°C  

Microsoft Academic Search

The solubility of argon in pure liquid water was measured at ca. 100 kPa and from 2 to 40°C using an analytical method characterized by an imprecision of about ±0.05%. From the experimental results, Henry fugacities H2,1(T,Ps,1) (also known as Henry's Law constants or Henry coefficients) at the vapor pressure Ps,1 of water as well as Ostwald coefficients L2,18 at

T. R. Rettich; Rubin Battino; Emmerich Wilhelm

1992-01-01

286

Oxygen deficit during incremental exercise  

Microsoft Academic Search

Summary  The oxygen deficit and debt have conventionally been determined during exercise at constant work rates. During this study these were calculated during and after exercise at progressively incremented work rates. Five men performed two successive incremental exercise tests to exhaustion on an electronically braked cycle ergometer. The two tests were separated by a 5 min rest period. The oxygen deficit

H. A. Davis; G. C. Gass; D. Eager; J. Bassett

1981-01-01

287

Appreciating Oxygen  

ERIC Educational Resources Information Center

|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…

Weiss, Hilton M.

2008-01-01

288

Oxygen-Nitrogen Relationships in Autotrophic Nitrification  

PubMed Central

Oxygen utilization by the autotrophic nitrifiers Nitrosomonas and Nitrobacter was studied. Experimental evidence is presented which reflects the effect of carbon dioxide fixation on overall oxygen utilization in autotrophic nitrification. Measurement of dissolved oxygen and inorganic nitrogen changes indicates that oxygen-nitrogen ratios in inorganic nitrogen oxidation are equal to 3.22 parts (expressed in milligrams per liter) of oxygen per part of ammonia nitrogen oxidized to nitrite nitrogen and 1.11 parts of oxygen per part of nitrite nitrogen oxidized to nitrate nitrogen. These values rather than the stoichiometric ratios should be used in nitrogenous oxygen demand calculations.

Wezernak, C. T.; Gannon, J. J.

1967-01-01

289

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

PubMed

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

Thompson, Kelly; Zhang, Jianying; Zhang, Chunlong

2011-05-19

290

Experimental measurements of the graphite C-O equilibrium and CO2 fugacities at high temperature and pressure  

NASA Astrophysics Data System (ADS)

The f o 2 of the equilibrium between graphite and C-O fluid has been determined from 15-30 kbar and 1100-1400°C using a sliding redox sensor consisting of (Ni, Mn) O+Ni metal. The equilibrium composition of oxide coexisting with metal was approached from both directions in each experiment with convergence to within 1 mol% NiO. Since, in the P-T range of the experiments, C-O fluids are >90% CO2 our measurements of f o 2 translate into determinations of CO2 fugacity with an uncertainty of ±0.1 log units. These new determinations of the P-T-f o 2 plane of GCO equilibrium are in excellent agreement with the mainly unreversed measurements of Ulmer and Luth (1991) using pure metal-metal oxide sensors and with the equation of state of Saxena and Fei (1987). Modified forms of the Redlich-Kwong (MRK) equation of state (Holloway 1977; Flowers 1979; Kerrick and Jacobs 1981) predict higher values of f o 2 for the GCO equilibrium than determined experimentally. This implies that CO2 is more compressible than the MRK predicts.

Frost, Daniel J.; Wood, Bernard J.

1995-09-01

291

Estimating dermal uptake of nonionic organic chemicals from water and soil: I. Unified fugacity-based models for risk assessments  

SciTech Connect

Contamination of water and soil that might eventually contact human skin makes it imperative to include the dermal uptake route in efforts to assess potential environmental health risks. Direct measurements of dermal uptake from either water or soil are only available for a small number of the thousands of chemicals likely to be found in the environment. We propose here a mass-transfer model for estimating skin permeability and dermal uptake for organic chemicals that contaminate soil and water. Statistical relationships between measured permeabilities and chemical properties reveal that permeability varies primarily with the octanol-water partition coefficient (K[sub ow]) and secondarily with the molecular weight. From these results, we derive a fugacity-based model for skin permeability that addresses the inherent permeability of the skin, the interaction of the skin with the environmental medium on skin (water or soil), and retains a relatively simple algebraic form. Model predictions are compared to measured human skin permeabilities for some 50 compounds in water and four compounds in soil. The model is adjusted to account for dermal uptake during both short-term (10-20 min) and long-term (several hour) exposures. This model is recommended for compounds with molecular weight less than or equal to 280 g.

McKone, T.E. (Lawrence Livermore National Lab., CA (United States)); Howd, R.A. (California Environmental Protection Agency, Sacramento (United States))

1992-12-01

292

Home Oxygen Therapy  

MedlinePLUS

... common ways of providing home oxygen therapy: A liquid oxygen system; A standard oxygen concentrator, and A ... home oxygen is examined in more detail below. Liquid Oxygen – Oxygen is stored as a very cold ...

293

Oxygen production and consumption in sediments determined at high spatial resolution by computer simulation of oxygen microelectrode data  

Microsoft Academic Search

Microprofiles of oxygen and oxygenic photosynthesis were measured in a photosynthetically active sediment by an oxygen microelectrode. The di&.tsion coefficient of oxygen in the uppermost 1 mm of the sediment was determined in poisoned sediment by microelectrode measurement of changes in the oxygen profile during nonsteady state conditions. The experimentally obtained data were inserted into computer models to calculate the

NIELS PETER REVSBECH; BENT MADSEN; BO BARKER JØRGENSEN

1986-01-01

294

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

Microsoft Academic Search

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

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

2010-01-01

295

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

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

296

Influence of oxygen vacancy on the electronic structure of CaCu3Ti4O12 and its deep-level vacancy trap states by first-principle calculation  

NASA Astrophysics Data System (ADS)

The electronic structure, formation energy, and transition energy levels of intrinsic defects have been studied using the density-functional method within the generalized gradient approximation for neutral and charged oxygen vacancy in CaCu3Ti4O12 (CCTO). It is found that oxygen vacancies with different charge states can be formed in CCTO under both oxygen-rich and poor conditions for nonequilibrium and higher-energy sintering processes; especially, a lower formation energy is obtained for poor oxygen environment. The charge transition level (0/1+) of the oxygen vacancy in CCTO is located at 0.53 eV below the conduction-band edge. The (1+/2+) transition occurs at 1.06 eV below the conduction-band edge. Oxygen vacancies of Vo1+ and Vo2+ are positive stable charge states in most gap regions and can act as a moderately deep donor for Vo1+ and a borderline deep for Vo2+, respectively. The polarization and dielectric constant are considerably enhanced by oxygen vacancy dipoles, due to the off-center Ti and Cu ions in CCTO.

Xiao, H. B.; Yang, C. P.; Huang, C.; Xu, L. F.; Shi, D. W.; Marchenkov, V. V.; Medvedeva, I. V.; Bärner, K.

2012-03-01

297

The Natural History of Oxygen  

PubMed Central

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.

Dole, Malcolm

1965-01-01

298

Solute effect on oxygen diffusion in ?-titanium  

NASA Astrophysics Data System (ADS)

We calculate first-principles interaction energies between substitutional solutes and oxygen interstitials in ?-titanium and predict the effect of solutes on oxygen diffusion from those interactions. Interaction between 45 solutes across the periodic table and three oxygen interstitial sites are calculated with density-functional theory. The interaction energies show distinct trends across the periodic table corresponding to both atomic radii and the period. Changes in diffusion barrier due to solutes are modeled with the kinetically resolved activation barrier approximation. Solute effects at infinite dilution are numerically calculated and show both accelerated and reduced oxygen diffusivity.

Wu, Henry H.; Trinkle, Dallas R.

2013-06-01

299

Oxygen vacancies in monoclinic hafnia  

NASA Astrophysics Data System (ADS)

Hafnia has recently received much attention because of its potential application as high-dielectric material replacing silica in microelectronic devices. Point defects -- in particular oxygen vacancies -- play an important role in this material as electron or hole traps. In this study, we perform electronic structure calculations on oxygen vacancies in hafnia using a combined Density functional Theory (DFT) and GW/BSE formalism. This formalism corrects for the error in calculating formation energy and charge transition levels using standard DFT. While there have been some GW studies on oxygen vacancies in hafnia using small supercells, we perform calculations using large supercells with 96 atoms. Such a large supercell calculation should minimize any spurious defect-defect interactions.

Jain, Manish; Chelikowsky, James R.; Louie, Steven G.

2010-03-01

300

Oxygen therapy and oxygen toxicity.  

PubMed

When oxygen therapy is warranted, the minimum effective dose generally should be given. Hypoxemic patients who have normal baseline ABG may be treated initially with an intermediate to high FiO2 in the range of 35% to 100%, depending on the severity of the respiratory distress. The majority of patients with exacerbations of COPD who are not in extremis may be given an initial FiO2 of 28%, especially if their previous response to oxygen is known. When treating patients who have chronic severe hypercapnia (eg, those requiring chronic home oxygen), the initial FiO2 should be 24% even though renal compensation of the respiratory acidosis has occurred. Further mild elevation of the PaCO2, due mainly to the V/Q mismatch that oxygen therapy induces, may be sufficient to precipitate unacceptable hypercapnia. Patients with exacerbations of COPD who are obviously in extremis, with severe hypoxemia and acidosis, should start with an FiO2 of 24% unless they are being mechanically ventilated. The severity of the hypoxemia and acidosis is more predictive for the development of CO2 narcosis and respiratory failure than is the degree of hypercapnia in these patients. The FiO2 can be increased to 28% and incrementally higher if low FiO2 is tolerated. The use of a high FiO2 is subject to the following guidelines for prevention of clinically significant oxygen toxicity: 100% oxygen at atmospheric pressure is safe if given for less than six hours; 70% oxygen is probably safe for 24 hours; and after this time, 45% should be the approximate upper limit to the FiO2.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6414343

Tinits, P

1983-05-01

301

Electronic Calculators.  

National Technical Information Service (NTIS)

Because of the large number of different makes and models of electronic calculators available, it is often difficult to select the calculator best suited for a particular application. This compendium was written to aid potential calculator users in making...

E. A. Pfeiffer

1973-01-01

302

Percentage of Oxygen in the Air  

NSDL National Science Digital Library

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.

Muller, Eric

2000-01-01

303

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

USGS Publications Warehouse

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

Tuthill, R. L.; Sato, M.

1970-01-01

304

CO2-related explosive alkaline magmatism in Gusev crater, Mars: Implications for oxygen fugacity and carbon inventory in the Noachian Martian mantle (Invited)  

Microsoft Academic Search

The Mars Exploration Rover Spirit has encountered volcanic and volcaniclastic rocks having diverse alkaline compositions in the Noachian-age (~3.8-4.5 Ga) Gusev crater. Among them, we focus on Wishstone Class tephrites which have pyroclastic textures and are unusually enriched in incompatible elements (e.g. >5 wt% P2O5) with low silica contents. The high-phosphorous tephrite signature is not attributable to secondary aqueous alteration

T. Usui; H. Y. McSween; B. C. Clark

2010-01-01

305

Experimental investigation of the effect of oxygen fugacity on ferric-ferrous ratios and unit-cell parameters of four natural clinoamphiboles  

Microsoft Academic Search

but the results suggest that other mechanisms may also be involved. All four amphiboles exhibited systematically higher ferric-ferrous ratios with increasing 6, of equilibration. Equilibrium R values were achieved relatively rapidly and could be readily restored to onginal values by treatment at the appropriate buffer. In some cases, a metastable equi- librium of ferric-ferrous ratio was achieved before the amphibole

A. Cr-own; Ronnnr K. Popp

306

Pb diffusion in Cr diopside, augite, and enstatite, and consideration of the dependence of cation diffusion in pyroxene on oxygen fugacity  

Microsoft Academic Search

Chemical diffusion of Pb under anhydrous, pO2-buffered conditions has been measured in natural pyroxenes of three different compositions: a chromian diopside, an augitic clinopyroxene, and a near-end member enstatite. Sources of diffusant consisted of PbS powder and ground pyroxene mixed together, pre-reacted in evacuated silica capsules at 1050°C, and re-ground. Prepared sample capsules were annealed for times ranging from several

D. J. Cherniak

2001-01-01

307

The solubility and oxidation state of nickel in silicate melt at low oxygen fugacities: Results using a mechanically assisted equilibration technique  

Microsoft Academic Search

The data presented in this paper indicate that the oxidation state of Ni in the investigated melt is Ni2* over the entire range of fo, investigated. This conclusion contrasts with recent reports in the literature of an inflection in the fo, dependence of Ni solubility, which has been interpreted as solution of neutral Ni at low fo, (MORSE et al.,

D. B. DINGWELL; H ONEILL; W. ERTEL; B. SPETTEL

1994-01-01

308

Oxygen Toxicity.  

National Technical Information Service (NTIS)

Prolonged exposure to increased partial pressure of oxygen can result in toxic effects which become progressively more severe as the inspired partial pressure and/or duration of exposure is increased. The most dramatic of these are toxic effects upon the ...

T. C. Schmidt R. W. Hamilton

1973-01-01

309

Electrical conductivity of San Carlos olivine along [100] under oxygen- and pyroxene-buffered conditions and implications for defect equilibria  

SciTech Connect

The electrical conductivity along [100] of single crystal San Carlos olivine was measured as a function of temperature between 1100[degrees] and 1200[degrees]C and oxygen fugacity between 10[sup [minus]6] and 10[sup +0.5] Pa (at 1200[degrees]C), and either with (pyroxene-buffered) or without (self-buffered) an added natural pyroxene buffer from a San Carlos Iherzolite. Under these temperature and fO[sub 2] conditions, electrical conduction in the self-buffered sample is attributed to polarons (Fe[sup [sm bullet

Wanamaker, B.J.; Duba, A.G. (Lawrence Livermore National Lab., CA (United States))

1993-01-10

310

The Expansion of Gases on Mixing, Especially at Very Low Pressures. I. Its Relation to the Empirical Calculation of the Fugacities in Gaseous Mixtures  

Microsoft Academic Search

From plots of the expansion of a gas in a mixture, (v¯1-v1), or of the expansion of gases on mixing to form a mole of mixture from the pure gases at constant temperature and pressure, (Sigmax1v¯1- Sigmax1v1), as functions of the pressure, it is clear that these quantities do not vanish at zero pressure. These expansions do not vanish for

Louis J. Gillespie

1929-01-01

311

Luminosity calculation  

SciTech Connect

The luminosity of the Tevatron collider was calculated. The data used for the calculation are the flying wire transverse beam profile and the SBD bunch profile. For the 900 GeV/c mini beta runs, the calculation was compared to the CDF luminosity monitor. The ratio of the calculation and C:BOLUMP is 0.95. 1 ref., 9 figs., 4 tabs.

Hsueh, Shao-Yuan.

1989-12-01

312

Oxygen analyzer  

SciTech Connect

An oxygen analyzer is described which consists of: a pyrolysis tube, a temperature programmed oven through which the pyrolysis tube extends, a pyrolysis oven into which the pyrolysis tube extends, a quantity of granular carbon located in a portion of the pyrolysis tube within the pyrolysis oven and adapted to be heated to a temperature of about 1135/sup 0/C by the pyrolysis oven, means for moving a sample of material to be analyzed through the pyrolysis tube so as to position a sample of material to be analyzed in either the temperature programmed oven or the pyrolysis oven, a computer operatively connected to the temperature programmed oven for increasing the temperature of the oven as a function of time, detector means operatively connected to the pyrolysis oven to receive gaseous material from the oven, the computer also being operatively connected to the detector means so as to receive input signals from the detector means relative to measurement of gaseous material directed through the detector means, and means for backflushing the pyrolysis tube with nitrogen gas, whereby, a sample of oxygen containing material is decomposed and converted to carbon monoxide within at least one of the ovens for subsequent detection such that microgram quantities of oxygen in a sample being analyzed can be determined.

Benner, W.H.

1986-07-22

313

Determination of Oxygen Self-Diffusion in Akermanite, Anorthite, Diopside, and Spinel: Implications for Oxygen Isotopic Anomalies and the Thermal Histories of Ca-Al-rich Inclusions  

NASA Astrophysics Data System (ADS)

Oxygen self-diffusion coefficients have been measured for three natural clinopyroxenes (diopside end member), a natural anorthite, a synthetic magnesium aluminate spinel, and a synthetic akermanite over oxygen fugacities ranging from the NNO to IW buffers. The experiments employed a gas-solid isotopic exchange technique utilizing 99% ^18O-enriched COCO2 gas mixtures to control both the oxygen fugacity and the isotopic composition of the exchange reservoir. Diffusion profiles of the ^18O tracer were obtained by in-depth analysis with an ion microprobe. The experimental results yield Arrhenius relations that appear here in the hard copy. At a given temperature, oxygen diffuses about 100 times more slowly in diopside than indicated by previous bulk-exchange experiments [1]. Our data for anorthite, spinel, and akermanite agree well with prior results obtained by gas-solid isotopic exchange and depth profiling methods [2-4]. Since these other experiments were conducted at different oxygen fugacities, this agreement indicates that diffusion of oxygen in these nominally iron-free minerals is not greatly affected by fO2 in the range between pure oxygen and the iron-wustite buffer. The oxygen diffusion data are used to evaluate the effects of three different types of therrnal histories upon the oxygen isotopic compositions of minerals found in Type B calciumaluminum-rich inclusions (CAIBs): (1) gas-solid exchange during isothermal heating, (2) gassolid exchange due to instantaneous heating followed by cooling at different rates, and (3) isotopic exchange with a gaseous reservoir during partial melting and recrystallization. With the assumptions that the mineral compositions within a CAIB were uniformly enriched in ^16O prior to any thermal processing, that effective diffusion dimensions may be estimated from observed grain sizes, and that diffusion in diopside is similar to that in fassaite, all the above scenarios fail to reproduce either the relative oxygen isotopic anomalies observed in CAIBs and/or yield improbably long or unrealistically intense thermal histories relative to both current theoretical models of nebular evolution and inferences from other isotopic systems. The failure of these simple models, coupled with recent observations of "disturbed" Mg isotopic abundances and petrographic features in anorthite and melilite indicative of alteration and recrystallization [5,6], suggests that the oxygen isotopic compositions of these phases may have also been modified by alteration and recrystallization during multiple melting events. Because the modal abundance of spinel remains relatively constant for plausible melting scenarios and its relatively sluggish diffusion kinetics prevent substantial equilibration, Mg-Al spinel is a reliable indicator of the oxygen isotopic composition of precursor material that formed CAIBs. References: [1] Connolly C. and Muehlenbachs K. (1988) GCA, 52, 1585-1592. [2] Elphick S. C. et al. (1988) Contrib. Mineral. Petrol., 100, 490-495. [3] Reddy K. P. and Cooper A. R. (1981) J. Am. Ceram. Soc., 64, 368-371. [4] Yunmoto H. et al. (1989) GCA, 53, 2387-2394. [5] Podosek F. A. et al. (1991) GCA, 55, 1083-1110. [6] MacPherson G. J. and Davis A. M. (1993) GCA, 57, 231-243.

Ryerson, F. J.; McKeegan, K. D.

1993-07-01

314

Determination of oxygen self-diffusion in åkermanite, anorthite, diopside, and spinel: Implications for oxygen isotopic anomalies and the thermal histories of Ca-Al-rich inclusions  

NASA Astrophysics Data System (ADS)

Oxygen self-diffusion coefficients have been measured for three natural diopsidic clinopyroxenes, a natural anorthite, a synthetic magnesium aluminate spinel, and a synthetic åkermanite for oxygen fugacities ranging from the NNO to IW buffers. The experiments employed a gas-solid isotopic exchange technique utilizing 99% 18O-enriched CO-CO2 gas mixtures to control both the oxygen fugacity and the isotopic composition of the exchange reservoir. Diffusion profiles of the 18O tracer were obtained by in-depth analysis with an ion microprobe. The experimental results, fit to the Arrhenius relation D = D0e(-QRT), yield the following: Do (m2 s-1)Q (kJ mol-1)diopside4.3- 3.8+32.6× 10 - 4457 ± 26åkermanite4.7- 4.4+83.5× 10 - 7457 ± 26278 ± 33spinel2.2- 1.8+8.7× 10 - 7404 ± 21anorthite8.4- 8.0+174× 10 - 13162 ± 36At a given temperature, oxygen diffuses about 100 times more slowly in diopside than indicated by previous bulk-exchange experiments (CONNOLLY and MUEHLENBACHS, 1988). Our data for anorthite, spinel, and åkermanite agree well with prior results obtained by gas-solid exchange and depth profiling methods (ELPHICK et al., 1988; REDDY and COOPER, 1981; YURIMOTO et al., 1989, respectively). Since these other experiments were conducted at different oxygen fugacities, this agreement indicates that diffusion of oxygen in these nominally Fe-free minerals is not greatly affected by fO2 in the range between pure oxygen and the iron-wüstite buffer. However, our diffusion coefficients for anorthite, melilite, and spinel are also uniformly lower than those obtained by bulk analysis of crushed powders at similar temperatures (MUEHLENBACHS and KUSHIRO, 1974; HAYASHI and MUEHLENBACHS, 1986; ANDO and OISHI, 1974).The oxygen diffusion data are used to evaluate the effects of three different types of thermal histories upon the oxygen isotopic compositions of minerals found in Type B Ca-Al-rich inclusions (CAIBs) in carbonaceous chondrites: (1) gas-solid exchange during isothermal heating,(2) gas-solid exchange as a function of cooling rate subsequent to instantaneous heating, and(3) isotopic exchange with a gaseous reservoir during partial melting and recrystallization. With the assumptions that the mineral compositions within a CAIB were uniformly enriched in 16O prior to any thermal processing, that effective diffusion dimensions may be estimated from observed grain sizes, and that diffusion in diopside is similar to that in fassaitic clinopyroxene, none of the above scenarios can reproduce the relative oxygen isotopic anomalies observed in CAIBs without improbably long or unrealistically intense thermal histories relative to current theoretical models of nebular evolution. The failure of these simple models, coupled with recent observations of “disturbed” magnesium isotopic abundances and correlated petrographic features in anorthite and melilite indicative of alteration and recrystallization, suggests that the oxygen isotopic compositions of these phases may have also been modified by alteration and recrystallization possibly interspersed with multiple melting events. Because the modal abundance of spinel remains relatively constant for plausible melting scenarios, and its relatively sluggish diffusion kinetics prevent substantial equilibration, Mg-Al spinel is the most reliable indicator of the oxygen isotopic composition of precursor material which formed Type B CAIs.

Ryerson, F. J.; McKeegan, Kevin D.

1994-09-01

315

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, ...

316

Calcium Calculator  

MedlinePLUS

... Fun Stuff Fun Stuff Best for Bones Food Calcium Calculator How much calcium do you get every day? Remember, you need ... Deal with Vitamin D List of Foods with Calcium & Vitamin D Calcium Calculator Fooling Around with Food ...

317

Bayesian Calculator  

NSDL National Science Digital Library

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.

Birnbaum, Michael H.

2009-01-15

318

Does contemporary oxygenator design influence haemolysis?  

PubMed

Based on their design, all membrane oxygenators generate a certain resistance to flow. In clinical practice, this resistance is calculated by measuring both blood flow and the pressure drop over the oxygenator. Historically, some designs, such as the Kolobow spiral coil oxygenator and the Cobe flat sheet oxygenator, had quite a high pressure drop, but were, nevertheless, considered very haemocompatible. Today, both medium and low pressure drop oxygenators are commercially available. Based on physics and the existing literature, this review aims to investigate whether pressure drop by itself can be considered an independent factor of haemolysis. PMID:23620546

De Somer, F

2013-04-25

319

Finite element multiconfiguration Hartree-Fock calculations on carbon, oxygen, and neon: The nuclear quadrupole moments of ¹¹C, ¹⁷O, and ²¹Ne  

Microsoft Academic Search

The authors report new calculations for the nuclear quadrupole moments of ¹¹C, ¹⁷O, and ²¹Ne, making use of a new finite-element multiconfiguration Hartree-Fock method. They calculate electric field gradients at the nuclei and combine these with measurements of nuclear quadrupole coupling constants to arrive at the values.

D. Sundholm; Olsen J

1992-01-01

320

Traveling with Portable Oxygen  

MedlinePLUS

... batteries that must be regularly replaced or recharged. Liquid Oxygen Liquid oxygen systems consist of lightweight units with a small reservoir that contains liquid oxygen. One example is the HELIOS Personal Oxygen ...

321

Oxygen distribution and speciation in bulk of monocrystalline diamonds and its correlations with other impurities  

NASA Astrophysics Data System (ADS)

Oxygen in diamond lattice remains elusive impurity. Mass-spectrometry and nuclear probes show presence of oxygen in all diamonds in concentrations ranging from <100 to 1000 at.ppm. Detailed studies [1] have shown that in virtually every diamond there exists "inclusion-independent" oxygen which is believed to be present as a structural impurity. Recent studies of natural diamonds showing strong absorption by CO2 in IR spectra [2] suggest that these monocrystalline diamonds contain oxygen as a lattice impurity. However, up until now evidence for incorporation of O during diamond growth is scarce and little is known about related defects. The aim of the current study is to show conclusively whether or not O can exist as a growth-related structural impurity in diamond. Several types of monocrystalline diamonds with and without CO2 IR absorption were analysed by techniques sensitive to chemical composition (SIMS) and to structure (Small-Angle X-ray Scattering (SAXS) and X-ray topography) [3]. For the SIMS investigation high ion current of 100 nA Cs+ ions in conjunction with an 8 µm field-of-view were employed. Due to prolonged storage of the sample mount in high vacuum conditions the O background signal was very low. Both spot analyses and mapping of O lateral and depth distributions were performed. In some CO2-rich diamonds oxygen is distributed heterogeneously at the micron-scale, suggesting its presence in submicron inclusions, which, in turn, are irregularly distributed throughout the sample. Such inclusions could correspond to heterogeneities with sizes of 100-200 nm revealed by SAXS. However, in some of these diamonds O is distributed homogeneously, suggesting that it might be present as a lattice impurity. The most important proof of structural position of oxygen impurity comes from simultaneous measurements of N and O concentrations. Plots of N vs O concentrations show clear correlations, obeyed as for several analyses spots on individual diamonds as well as for sets of diamonds. Notably, the slopes of the N-O correlations differ between diamonds showing CO2 absorption in IR and for "normal" diamonds. As expected, O contents are higher in the former group, suggesting that in CO2-rich diamonds oxygen is present both the lattice and in microscopic inclusions. This study is the first work showing correlation of structural nitrogen impurity with oxygen content of diamonds, thus providing strong analytical support for earlier hypothesis [2] that O may be present as a lattice impurity in natural diamonds. Theoretical calculations of relative stabilities of oxygen in diamond show a very strong dependence on the position of the Fermi level in the crystal [4, 5]. According to these results oxygen behaviour in diamond and, in particular, its diffusivity strongly depends on the nitrogen concentration and speciation. Though the O-N pair appears to be a stable defect at low temperatures, mutual repulsion of positively charged N and O ions creates a vacancy-like state in between them [5]. Since most impurities in diamond diffuse by a vacancy-assisted mechanism, such a configuration may be destroyed by annealing. The calculated strength of the C-O bond in diamond is lower than the C-C bond and preferential breaking of the C-O bond seems plausible. Therefore, despite its relatively common presence, oxygen is not always detected by spectroscopic methods if no annealing has been performed. Apparently, the presence of O hinders IR-activity of N-related defects. From the geochemical point of view the existence of oxygen as a lattice impurity in diamond is of considerable interest. First of all, it adds another important isotopic system in addition to C and N. Second, it emphasises the importance of the O partition coefficients in measurements of intrinsic oxygen fugacity of diamonds. References. [1] Sellschop, 1992 in The Properties of Natural and Synthetic Diamond. [2] Hainschwang et al., Diam.Relat.Mater. 340 (2008) [3] Shiryaev et al., J.Phys.Cond.Mat., vol. 21, p 045801 (2010) [4] Gali et al., J.Phys.Cond.Mat

Shiryaev, Andrei; Wiedenbeck, Michael; Hainschwang, Thomas

2010-05-01

322

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

SciTech Connect

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

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

2007-10-01

323

Phasor Calculator  

NSDL National Science Digital Library

Nick Reeder from Sinclair Community College created this interactive tool to compute with phasors when you're analyzing AC circuits. The phasor calculator allows you to add, subtract, multiply, or divide phasors. Use E to enter numbers in exponential form, such as 50E3 for 50 kilo. Press the = button to calculate result. Use the 1/x buttons to invert either operand.

Reeder, Nick

2011-05-09

324

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 Âtax supported entities world wide. 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 Âcalculator to include such things as name translators and databases on animal breeds.

325

Calcium Calculator  

MedlinePLUS

... form Search - A + A You are here Home - Calcium Calculator Printer friendly Email Share Tweet Like Home ... Regional Audits Reports Facts and Statistics Popular content Calcium-rich foods The Board What is Osteoporosis? Treating ...

326

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.

327

Modeling [15O] oxygen tracer data for estimating oxygen consumption  

PubMed Central

The most direct measure of oxidative tissue metabolism is the conversion rate of oxygen to water via mitochondrial respiration. To calculate oxygen consumption from the analysis of tissue residue curves or outflow dilution curves after injection of labeled oxygen one needs realistic mathematical models that account for convection, diffusion, and transformation in the tissue. A linear, three-region, axially distributed model accounts for intravascular convection, penetration of capillary and parenchymal cell barriers (with the use of appropriate binding spaces to account for oxygen binding to hemoglobin and myoglobin), the metabolism to [15O]water in parenchymal cells, and [15O]water transport into the venous effluent. Model solutions fit residue and outflow dilution data obtained in an isolated, red blood cell-perfused rabbit heart preparation and give estimates of the rate of oxygen consumption similar to those obtained experimentally from the flow times the arteriovenous differences in oxygen contents. The proposed application is for the assessment of regional oxidative metabolism in vivo from tissue 15O-residue curves obtained by positron emission tomography.

Deussen, Andreas; Bassingthwaighte, James B.

2010-01-01

328

Dissolved Oxygen and Temperature  

Microsoft Academic Search

Dissolved oxygen and temperature are two of the fundamental variables in lake and pond ecology. By measuring dissolved oxygen and temperature, scientists can gauge the overall condition of waterbodies. Aquatic organisms need dissolved oxygen for their survival. While water temperature also directly influences aquatic organ- isms, it regulates dissolved oxygen concentrations within a lake. Dissolved oxygen and temperature are also

Kelly Addy; Linda Green

329

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.

2010-03-02

330

Dissolved Oxygen and Biochemical Oxygen Demand  

NSDL National Science Digital Library

This 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.

Agency, U. S.

331

First-principles calculations of 17O nuclear magnetic resonance chemical shielding in Pb(Zr1/2Ti1/2)O3 and Pb(Mg1/3Nb2/3)O3: Linear dependence on transition-metal/oxygen bond lengths  

NASA Astrophysics Data System (ADS)

First-principles density functional theory oxygen chemical shift tensors were calculated for A(B,B')O3 perovskite alloys Pb(Zr1/2Ti1/2)O3 (PZT) and Pb(Mg1/3Nb2/3)O3 (PMN). Quantum chemistry methods for embedded clusters and the gauge including projector augmented waves (GIPAW) method [C. J. Pickard and F. Mauri, Phys. Rev. B 63, 245101 (2001)] for periodic boundary conditions were used. Results from both methods are in good agreement for PZT and prototypical perovskites. PMN results were obtained using only GIPAW. Both isotropic ?iso and axial ?ax chemical shifts were found to vary approximately linearly as a function of the nearest-distance transition-metal/oxygen bond length, rs. Using these results, we argue against Ti clustering in PZT, as conjectured from recent 17O NMR magic-angle-spinning measurements. Our findings indicate that 17O NMR measurements, coupled with first-principles calculations, can be an important probe of local structure in complex perovskite solid solutions.

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

2011-09-01

332

[Home oxygen therapy using liquid oxygen system].  

PubMed

Home oxygen therapy (HOT) for patients with chronic respiratory failure has been believed to increase the quality of life and to improve the prognosis of such patients. In Japan, HOT for chronic respiratory failure has been supported by health insurance since March 1985. Since then, patients with HOT have increased progressively, and it has been reported that there are now over 20,000 patients with HOT. The oxygen concentrator which extracts oxygen from atmospheric air has been commonly used as the oxygen delivery system. Recently the liquid oxygen system has provided an attractive, convenient source of oxygen. Since April 1990, HOT using liquid oxygen system has been supported by health insurance, and its use will become widespread in Japan. A major characteristic of this system is that oxygen condensed into a liquid form allows storage of a larger supply. This system consists of two parts: stationary type which stores the liquid oxygen, and a portable type which can easily be refilled with oxygen a larger source. In the present study, we examined the efficacy of portable liquid oxygen in 50 patients with chronic pulmonary diseases including patients with chronic respiratory failure who had PaO2 < 55 mmHg during air breathing. We measured changes of ten minutes walking distance (10 MD) and blood gas analysis with and without portable liquid oxygen. We also performed on estimation of efficacy of liquid oxygen by questionnaires in patients receiving liquid oxygen for HOT. We did not find a significant improvement of 10 MD with portable liquid oxygen, but found a significant improvement of arterial oxygen tension at the end of walking.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1306220

Hida, W; Sakurai, M; Okabe, S; Hajime; Kurosawa; Kikuchi, Y; Takishima, T

1992-12-01

333

Tracing Calculation (Calque Calcul) Between  

Microsoft Academic Search

To calculate the loss—is this the challenge that Nicolas Abraham has given to Jacques Derrida? Between 1959 and 1975, the year of Abraham's unexpected death, they were close friends, sharing what Elisabeth Roudinesco describes as \\

Nicolas Abraham; Jacques Derrida; Laurie Johnson

334

Blood oxygen binding in hypoxaemic calves.  

PubMed

Blood oxygen transport and tissue oxygenation were studied in 28 calves from the Belgian White and Blue breed (20 healthy and 8 hypoxaemic ones). Hypoxaemic calves were selected according to their high respiratory frequency and to their low partial oxygen pressure (PaO2) in the arterial blood. Venous and arterial blood samples were collected, and 2,3-diphosphoglycerate, adenosine triphosphate, chloride, inorganic phosphate and hemoglobin concentrations, and pH, PCO, and PO2 were determined. An oxygen equilibrium curve (OEC) was measured in standard conditions, for each animal. The arterial and venous OEC were calculated, taking body temperature, pH and PCO2 values in arterial and venous blood into account. The oxygen exchange fraction (OEF%), corresponding to the degree of blood desaturation between the arterial and the venous compartments, and the amount of oxygen released at the tissue level by 100 mL of blood (OEF Vol%) were calculated from the arterial and venous OEC combined with the PO2 and hemoglobin concentration. In hypoxaemic calves investigated in this study, the hemoglobin oxygen affinity, measured under standard conditions, was not modified. On the contrary, in vivo acidosis and hypercapnia induced a decrease in the hemoglobin oxygen affinity in arterial blood, which combined to the decrease in PaO2 led to a reduced hemoglobin saturation degree in the arterial compartment. However, this did not impair the oxygen exchange fraction (OEF%), since the hemoglobin saturation degree in venous blood was also diminished. PMID:12056479

Cambier, Carole; Clerbaux, Thierry; Detry, Bruno; Marville, Vincent; Frans, Albert; Gustin, Pascal

335

Calculation Nation  

NSDL National Science Digital Library

These games from NCTM Illuminations are organized around content from the upper elementary and middle grades math curriculum. Students can play online math strategy games with opponents from anywhere in the world, or challenge themselves by investigating significant mathematical content and practicing fundamental skills. Games focus on fractions, factors, multiples, symmetry and more, as well as practice on basic multiplication and calculating area.

Illuminations, Nctm

2009-04-23

336

Mercury Calculator  

NSDL National Science Digital Library

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.

Foundation, Wgbh E.

2010-12-23

337

Oxygen Transfer to Ethylene Catalyzed by the Ag(110) Surface.  

National Technical Information Service (NTIS)

The silver surface catalyzed epoxidation of ethylene using molecular oxygen as an oxygen donor been studied using extended Huckel calculations. Five types of absorbed molecular oxygen on an Ag(110) surface have been considered, an end-on adsorption on top...

K. A. Jorgensen R. Hoffmann

1989-01-01

338

A calcium oxygen secondary battery  

NASA Astrophysics Data System (ADS)

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

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

1988-01-01

339

Oxygen Transport Ceramic Membranes  

SciTech Connect

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.

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

2005-02-01

340

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

SciTech Connect

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).

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

341

Watershed modeling of dissolved oxygen and biochemical oxygen demand using a hydrological simulation Fortran program  

Microsoft Academic Search

Several inland water bodies in the St. Louis Bay watershed have been identified as being potentially impaired due to low level of dissolved oxygen (DO). In order to calculate the total maximum daily loads (TMDL), a standard watershed model supported by U.S. Environmental Protection Agency, Hydrological Simulation Program Fortran (HSPF), was used to simulate water temperature, DO, and bio-chemical oxygen

Zhijun Liu; Janna M. Kieffer; William L. Kingery; David H. Huddleston; Faisal Hossain

2007-01-01

342

Oxygen Diffusion in the Brain. Part 2 Oxygen Diffusion with O2 Deficiency.  

National Technical Information Service (NTIS)

On the basis of certain assumptions and calculations, the following points arise: Under normal conditions, the brain works with an excess of oxygen, with an oxygen pressure reserve of about 9 mmHg. Within this region, the reduction of arterial or venous p...

K. Diemer

1972-01-01

343

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 ...

344

Dissolved Oxygen Protocol  

NSDL National Science Digital Library

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.

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

2003-08-01

345

[Mathematical modeling of oxygen diffusion and consumption in malignant tumor].  

PubMed

A mathematical model of oxygen diffusion and consumption in a malignant spherical tumor was developed. The model takes into account the dependence of the rate of oxygen consumption by cells on oxygen concentration. The expressions for the description of the dependence of oxygen concentration on the coordinate in the tumor are presented. Some model parameters were estimated from known experimental data. The hypoxic cells fraction (index related to tumour radioresistance) at critical and limiting tumor sizes were calculated. PMID:15977846

Knigavko, V G; Bondarenko, M A

346

Effect of Bleeding Oxygen on Processes in the Ion Source of an EMAL-2 Mass Spectrometer in the Analysis of Oxygen-Containing Samples  

Microsoft Academic Search

When bleeding oxygen into the ion source of an EMAL-2 laser mass spectrometer, an oxygen monolayer was formed on atomically pure sample surfaces produced by laser scanning. It was found that the signal of this oxygen can be used for calculating sensitivity factors. Bleeding oxygen increased the yield of test sample matrix ions; for example, the yield of Fe+ ions

V. S. Sevast'yanov; N. E. Babulevich; D. A. Tyurin; S. M. Sil'nov

2003-01-01

347

Defects and oxygen diffusion in PuO 2? x  

Microsoft Academic Search

A thermochemical model of defects formation is proposed. Using this model, defect species concentrations are determined. The model allows for the calculation of the non-stoichiometry of PuO2?x, as functions of temperature and oxygen pressure. A model of oxygen diffusion is proposed and the oxygen self and chemical diffusivities are calculated for temperatures in the (900–1400°C) range and partial pressure of

M. Stan; P. Cristea

2005-01-01

348

The effect of activity on oxygen consumption, oxygen debt, and heart rate in the lizards Varanus gouldii and sauromalus hispidus  

Microsoft Academic Search

Oxygen consumption and heart rate were measured during rest and activity in the lizardsVaranus gouldii andSauromalus hispidus. Oxygen debt was calculated from postactive oxygen consumption. Standard metabolic rates of the two animals are similar butVaranus consumes much more oxygen during activity than doesSauromalus (Fig. 1–3). The latter has a constant active metabolic rate above 30 ° C and accumulates a

Albert F. Bennett

1972-01-01

349

The story of oxygen.  

PubMed

The history of oxygen from discovery to clinical application for patients with chronic lung disease represents a long and storied journey. Within a relatively short period, early investigators not only discovered oxygen but also recognized its importance to life and its role in respiration. The application of oxygen to chronic lung disease, however, took several centuries. In the modern era, physiologists pursued the chemical nature of oxygen and its physiologic interaction with cellular metabolism and gas transport. It took brazen clinicians, however, to pursue oxygen as a therapeutic resource for patients with chronic lung disease because of the concern in the 20th century of the risks of oxygen toxicity. Application of ambulatory oxygen devices allowed landmark investigations of the long-term effects of continuous oxygen that established its safety and efficacy. Although now well established for hypoxic patients, many questions remain regarding the benefits of oxygen for varying severity and types of chronic lung disease. PMID:23271817

Heffner, John E

2013-01-01

350

Probability Calculator  

NSDL National Science Digital Library

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.

Stark, Philip B.

2009-01-08

351

Solid state oxygen sensor  

DOEpatents

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.

Garzon, F.H.; Chung, B.W.; Raistrick, I.D.; Brosha, E.L.

1996-08-06

352

Solid state oxygen sensor  

DOEpatents

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.

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

353

Living Without Oxygen: Oxygen Tolerance in Bacteria  

NSDL National Science Digital Library

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.

Harris, Sharon

354

Thermographic observation of hydrocarbon oxygen explosions  

Microsoft Academic Search

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.

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

1985-01-01

355

Oxygen deficit and repayment in submaximal exercise  

Microsoft Academic Search

Oxygen deficit and repayment ratios were investigated at various work loads, intensities and durations. An active baseline\\u000a was used (walking at 60 m\\/min) from which deficit and repayment values were calculated. Oxygen uptake (VO2) and core temperatures were measured in 30 males at baseline and during treadmill running (140 m\\/min) for randomly assigned\\u000a durations (0.5 ... 20 min). Measurements were

Donald F. McMiken

1976-01-01

356

Hemoglobin-oxygen equilibrium curves measured during enzymatic oxygen consumption.  

PubMed

A rapid, new method to measure hemoglobin-oxygen equilibrium curves is described using the protocatechuic acid/protocatechuic acid 3,4-dioxygenase system [C. Bull and D.P. Ballou (1981) J. Biol. Chem. 256, 12673-12680] to deoxygenate hemoglobin solutions enzymatically. The reaction is followed by simultaneous measurements of hemoglobin spectra using a diode array spectrophotometer and oxygen tensions using a polarographic O2 microelectrode. Multicomponent analysis allows the determination of fractions of oxyhemoglobin, deoxyhemoglobin, and high-spin and low-spin methemoglobins in each spectrum collected as the reaction proceeds. Fractional saturation as a function of oxygen partial pressure is calculated as the ratio of oxyhemoglobin to oxy- plus deoxyhemoglobin. Several advantages are offered by this method: (i) Hemoglobin-O2 binding curves are obtained rapidly and reproducibly; (ii) the speed of the reaction limits methemoglobin formation by autooxidation; (iii) there is no gas-liquid interface, eliminating protein denaturation at the surface; and (iv) direct calculations of fractional saturation are made using spectral analysis, thus avoiding the assumption of a linear transition between deoxy- and oxyhemoglobin. PMID:9466803

Vandegriff, K D; Rohlfs, R J; Magde, M D; Winslow, R M

1998-02-01

357

Chemical oxygen generation.  

PubMed

While pressurized oxygen in tank form, as well as oxygen concentrators, are ubiquitous in civilian healthcare in developed countries for medical use, there are a number of settings where use of these oxygen delivery platforms is problematic. These settings include but are not limited to combat casualty care and healthcare provided in extreme rural environments in undeveloped countries. Furthermore, there are a number of settings where delivery of oxygen other than the pulmonary route to oxygenate tissues would be of value, including severe lung injury, airway obstruction, and others. This paper provides a brief overview of the previous and current attempts to utilize chemical oxygen production strategies to enhance systemic oxygenation. While promising, the routine use of chemically produced oxygen continues to pose significant engineering and physiologic challenges. PMID:23271828

Ward, Kevin R; Huvard, Gary S; McHugh, Mark; Mallepally, Rajender R; Imbruce, Richard

2013-01-01

358

Solid state oxygen sensor  

DOEpatents

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.

Garzon, Fernando H. (Santa Fe, NM); Brosha, Eric L. (Los Alamos, NM)

1997-01-01

359

Oxygen Movement in Seagrasses  

Microsoft Academic Search

Measurements of oxygen variability and transport in seagrasses and other submerged plants are difficult to conduct and interpret\\u000a due to the existence of several sources and sinks of oxygen driving internal transport at different rates depending on conditions\\u000a in the water column and sediment. Oxygen release and transport in seagrasses have mostly been assessed by measuring oxygen\\u000a changes in incubation

Jens Borum; Kaj Sand-Jensen; Thomas Binzer; Ole Pedersen; Tina Maria Greve

360

Oxygen chemisorption on gold nanoparticles  

NASA Astrophysics Data System (ADS)

The catalytic properties of gold nanoparticles have been the subject of intense research activity over the last several years, after the discovery that nanometer-sized gold particles can catalyze common chemical reactions, such as CO oxidation, at room temperature. This is quite surprising, given the poor catalytic activity of gold surfaces, and their inability to chemisorb oxygen molecules. Guided by this observation, we have performed ab-initio density functional calculations of oxygen adsorption on neutral and negatively charged AuN clusters (N = 3 - 6), to determine their reactivity to molecular oxygen. We have found that: (i) Oxygen molecules do chemisorb on AuN clusters, with typical binding energies of 0.5 - 1 eV. (ii) In the most stable configuration, the O2 molecule dissociates, with the two O atoms forming a nearly linear O-Au-O bridge. (iii) Non-dissociative chemisorption of O2 molecules occurs at higher energy. Our results provide a fundamental understanding of the recently observed reactivity of gold clusters, and its dependence on the number of atoms in the cluster. This work was supported in part by the U.S. DOE Computational Materials Science Network grant DE-FG02-02ER45972.

Franceschetti, Alberto; Pantelides, Sokrates

2003-03-01

361

Trace Oxygen Analyser.  

National Technical Information Service (NTIS)

An electrolytic oxygen analyzer for the determination of oxygen impurities at the level of 0-100 ppM in inert gases (e.g. helium) is described. The analyzer has a built in oxygen generator which serves the purpose of self-calibration and provides a check ...

V. N. Vaidya M. R. Ponkshe P. S. inivasan J. K. Samuel D. D. Sood

1977-01-01

362

Determination of Oxygen Demand  

NASA Astrophysics Data System (ADS)

Oxygen demand is a commonly used parameter to evaluate the potential effect of organic pollutants on either a wastewater treatment process or a receiving water body. Because microorganisms utilize these organic materials, the concentration of dissolved oxygen is greatly depleted from the water. The oxygen depletion in the environment can have a detrimental effect on fish and plant life.

Hang, Yong D.

363

Analytic Reviews : Oxygen Toxicity  

Microsoft Academic Search

Oxygen therapy is administered to patients to decrease tissue hypoxia and to relieve arterial hypoxemia. High concentrations of oxygen often are used for short pe riods of time in patients with acute respiratory illnesses, and concentrations only slightly higher than ambient levels are administered for much longer time periods to patients with chronic respiratory diseases. Supplying oxygen to plants, animals,

Stephen G. Jenkinson

1988-01-01

364

Device for measuring oxygen  

NASA Astrophysics Data System (ADS)

A digital electronic device for measuring traces of oxygen in superfine and inert atmospheres was developed. The digital oxymeter operates on the principle of continuous electrochemical reduction of oxygen on a cathode-polarized selective oxygen electrode. The special structure of the selective electrode ensures a reading of the device independent of nature, temperature and total pressure of the gas mixture.

1984-07-01

365

Atomic Oxygen Profile Measurements  

Microsoft Academic Search

A series of atomic oxygen profiles are presented that show evidence that silver film sensors provide reliable measurements of atomic oxygen density in the 90- to 120-km altitude range, Measurements were made at Wallops Island, Virginia, and Point Barrow, Alaska. The much lower atomic oxygen density observed for the high-latitude winter and spring shots is discussed in terms of the

Watson R. Henderson

1974-01-01

366

Ambient Oxygen Promotes Tumorigenesis  

Microsoft Academic Search

Oxygen serves as an essential factor for oxidative stress, and it has been shown to be a mutagen in bacteria. While it is well established that ambient oxygen can also cause genomic instability in cultured mammalian cells, its effect on de novo tumorigenesis at the organismal level is unclear. Herein, by decreasing ambient oxygen exposure, we report a ?50% increase

Ho Joong Sung; Wenzhe Ma; Matthew F. Starost; Cory U. Lago; Philip K. Lim; Michael N. Sack; Ju-Gyeong Kang; Ping-Yuan Wang; Paul M. Hwang; Vladimir Brusic

2011-01-01

367

Automatic Electronic Oxygen Supply  

PubMed Central

An automatic electronic oxygen system has been devised to supply an intensive care unit with a “fail-safe” supply of continuous oxygen. All parts of the system are fitted with alarms, as the oxygen powers gas-driven ventilators. Since the system is cheap it can be installed in hospitals where finance is limited.

Ford, Patricia; Hoodless, D. J.

1971-01-01

368

Carbon distribution and fluxes during the SERIES iron fertilization experiment with special reference to the fugacity of carbon dioxide (fCO2)  

NASA Astrophysics Data System (ADS)

Surface seawater fugacity of carbon dioxide (fCO2) 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 fCO2 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 fCO2 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 CO2 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 CO2 drawdown values.

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

2006-10-01

369

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)

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.

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

2006-10-01

370

Dissolved Oxygen Activity  

NSDL National Science Digital Library

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.

Gordon, Steve

371

Dissolved Oxygen Model  

NSDL National Science Digital Library

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.

Gordon, Steve

372

Oxygen partial pressure sensor  

DOEpatents

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.

Dees, Dennis W. (Downers Grove, IL)

1994-01-01

373

Oxygen partial pressure sensor  

DOEpatents

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.

Dees, D.W.

1994-09-06

374

An ab initio study of oxygen on strained graphene  

NASA Astrophysics Data System (ADS)

Graphene under strain exhibits new fascinating properties. In this work, I show that lattice strain introduced by uniform expansion of unit cells can strongly modify the chemical properties of graphene. By employing density functional theory calculations I found that strain enhances the bonding between atomic oxygen and graphene. Strain also increases the diffusion energy barrier of atomic oxygen on graphene; however, it reduces the activation energy for oxygen migrating through the graphene sheet. Strong stability enhancement of atomic oxygen on graphene induced by strain would also change molecular oxygen dissociation reactions from endothermic to exothermic.

Nguyen, Manh-Thuong

2013-10-01

375

Importance of oxygen-haemoglobin binding to oxygen transport in congestive heart failure.  

PubMed Central

OBJECTIVE--To assess the importance of 2,3-diphosphoglycerate (2,3-DPG) and oxygen-haemoglobin binding to oxygen transport in patients with congestive heart failure. METHODS--In 30 patients with severe congestive heart failure, arterial, mixed venous, and coronary sinus venous blood concentrations of 2,3-DPG were measured and systemic output and coronary sinus blood flow were measured by a thermodilution technique. Oxygen-haemoglobin affinity was expressed as the oxygen tension in mm Hg at which blood is 50% saturated with oxygen (P50). RESULTS--Compared with normal values, 2,3-DPG was high in arterial blood (2.58 mumol/ml, p = 0.01; 20.8 mumol/g haemoglobin, p < 0.0001). Significant gradients between arterial, mixed venous, and coronary sinus blood 2,3-DPG concentrations were also found (mixed venous = 2.40 mumol/ml, p = 0.05 v arterial blood; coronary sinus venous blood = 2.23 mumol/ml, p < 0.04 v arterial blood). P50 was correspondingly high compared with the accepted normal value (mean 29.7 mm Hg, normal 26.6 mm Hg, p < 0.001). Systemic oxygen transport (351 ml O2/min/m2) varied directly with the forward cardiac index (r = 0.89, p < 0.0001). There was no relation between systemic oxygen transport and arterial oxygen content. Similarly, myocardial oxygen transport was found to vary directly with coronary sinus blood flow. Calculations of changes in cardiac index and coronary sinus blood flow at normal oxygen-haemoglobin binding indicate that a considerable increase in cardiac index and coronary blood flow would be required to maintain similar systemic and myocardial oxygen transport. CONCLUSIONS--In patients with severe heart failure increased 2,3-DPG and reduced oxygen-haemoglobin binding may be compensatory mechanisms that maintain adequate systemic and delivery of oxygen to myocardial tissue.

Bersin, R M; Kwasman, M; Lau, D; Klinski, C; Tanaka, K; Khorrami, P; DeMarco, T; Wolfe, C; Chatterjee, K

1993-01-01

376

Design Calculation Method for Capillary-Tube Oxygenators.  

National Technical Information Service (NTIS)

A semi-empirical graphic method to predict the performance of capillary-tube artificial lungs has been developed from a mathematical model and an extensive amount of in vitro data obtained under precisely controlled conditions. This graphical technique pr...

C. E. Lanham F. Villarroel

1972-01-01

377

Program developed for CO{sub 2} system calculations  

SciTech Connect

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.

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

378

Core-mantle partitioning of oxygen on Earth and Mars (Invited)  

NASA Astrophysics Data System (ADS)

Oxygen is potentially one of the important light elements in the Earth’s core, based on geophysical observations and high-pressure experimental studies of the solubility and partitioning of oxygen into liquid Fe metal. However, its concentrations in the Earth’s core, as well as in the cores of Mercury, Venus and Mars, are still poorly constrained. In addition to Fe, Ni and S are important components in the cores of terrestrial planets. For example, based on cosmochemical constraints, the Earth’s core is considered to have a low S content (e.g. <2 wt%), whereas the Martian core is likely to have a much higher S concentration of up to 14 wt%. It is therefore important to understand how O partitions between silicates/oxides and liquid Fe alloy in Ni- and S-bearing systems. We have experimentally investigated the partitioning of oxygen between ferropericlase, and liquid Fe-Ni, Fe-S, and Fe-Ni-S metal at conditions up to 24.5 GPa and 2746 K using the Kawai-type multi-anvil apparatus. Our experimental results show that adding 10-20 mol% Ni to the metallic Fe at a fixed oxygen fugacity reduces the concentration of oxygen in the liquid metal, for example, from ~3 mol % to ~2 mol %. In contrast, adding up to 30 mol % S to liquid Fe increases the oxygen concentration by as much as 10 mol %. Experiments to determine the combined effects of Ni and S show a decrease in the effect of Ni on oxygen partitioning as the concentration of S in the metal increases. Our experimental data, together with previous studies of melting phase relations of Fe-Ni and Fe-S metals, are fitted using a thermodynamic model (asymmetric, regular solution model). By extrapolating to CMB conditions, oxygen concentrations in the core can be constrained, assuming equilibrium with the bulk of the mantle. Given that the maximum oxygen content of the core, based on the density deficit, is 6-9 wt%, this extrapolation shows that the core must be undersaturated in oxygen with respect to the bulk of the mantle. Two end-member consequences of this conclusion are (1) that the very base of the mantle is strongly depleted in FeO and (2) the uppermost part of the outer core consists of a thin buoyant FeO-rich liquid layer, as suggested by some seismological studies. Assuming core-mantle equilibrium, the Martian core could contain up to 2-4 wt% oxygen and, due to cooling since core formation, a solid FeO-rich layer may have formed at the base of the Martian mantle.

Tsuno, K.; Frost, D. J.; Rubie, D. C.

2010-12-01

379

Estimation of Coal and Gas Properties for Gasification Design Calculations.  

National Technical Information Service (NTIS)

This report compiles gas properties such as enthalpy, heat capacity, viscosity, thermal conductivity, compressibility, latent heat of vaporization, and fugacity coefficients together with characteristics of coal and char. Mixing rules are provided that pe...

1971-01-01

380

Oscillator strengths for singly ionized oxygen  

Microsoft Academic Search

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

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

2009-01-01

381

Oxygen ion conducting materials  

DOEpatents

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.

Vaughey, John (Elmhurst, IL); Krumpelt, Michael (Naperville, IL); Wang, Xiaoping (Downers Grove, IL); Carter, J. David (Bolingbrook, IL)

2003-01-01

382

Rat splanchnic net oxygen consumption, energy implications.  

PubMed Central

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

Casado, J; Fernandez-Lopez, J A; Esteve, M; Rafecas, I; Argiles, J M; Alemany, M

1990-01-01

383

Arterialisation of transcutaneous oxygen and carbon dioxide  

Microsoft Academic Search

We compared previously calculated global correction factors for oxygen and carbon dioxide arterial\\/transcutaneous ratios with individual in vivo calibrations from the first arterial sample. In infants beyond the neonatal period and older children in vivo calibration confers little benefit over the use of a global calibration correction factor for transcutaneous carbon dioxide, and may reduce the precision with which arterial

E Broadhurst; P Helms; H Vyas; G Cheriyan

1988-01-01

384

Note on limiting oxygen index for halons  

Microsoft Academic Search

The limiting oxygen index (LOI) requires data that also may be used to calculate volume percentages. The latter are a more sensitive measure of inhibiting\\u000a effect. Expressing inhibiting effect in weight per unit volume allows direct comparison between Halons. Possible improvements\\u000a in the procedure are suggested.

Arthur B. Guise

1970-01-01

385

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

SciTech Connect

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

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

1999-07-01

386

The Fe-FeO buffer at lower mantle pressures and temperatures  

SciTech Connect

As a constraint on oxygen fugacity of the lower mantle, the iron-wuestite (IW) oxygen buffer has been calculated for temperatures to 3,000 K and pressures to 135 GPa using available thermochemical and thermophysical data for Fe, FeO, and O{sub 2}. At conditions corresponding to the core-mantle boundary and 670 km depth, respectively, the oxygen fugacity of this buffer is 10{sup 20} and 10{sup 3} Pa; oxygen activities referenced to these conditions are 10{sup {minus}9} and 10{sup {minus}13}.

Hirsch, L.M. (Los Alamos National Lab., NM (United States))

1991-07-01

387

Atomic oxygen in the upper atmosphere of Venus  

Microsoft Academic Search

The oxygen atom density in the upper atmosphere of Venus is estimated by comparing measurements of the total emission intensity in the O I 1304-A triplet line with results of theoretical calculations. The data were obtained by means of the multichannel UV diffraction spectrometer aboard the Venera 11 and Venera 12 probes. Oxygen atom densities of 3.7 x 10 to

V. S. Sholokhov; M. S. Burgin

1982-01-01

388

Production of Oxygen  

NSDL National Science Digital Library

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.

House, The S.

2013-05-15

389

Oxygen in the Sun  

Microsoft Academic Search

ATTENTION having recently been directed by Dr. Schuster and Mr. Meldola, in connection with my discovery of oxygen in the sun, to the location of the oxygen, it may be of interest to allude to some experiments to determine the question by direct observation of the image of the sun spectroscopically. For this purpose I used a spectroscope furnished with

Henry Draper

1878-01-01

390

Oxygen consumption in Diaptomus  

Microsoft Academic Search

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,

GABRIEL W. COMITA

1968-01-01

391

Durability of oxygen sensors  

Microsoft Academic Search

This report describes the results of dynamometer and vehicle durability testing from a variety of sources, as well as common causes of failure for oxygen sensors. The data indicates that oxygen sensors show low failure rates, even at mileages of 80,000 miles and beyond.

L. Snapp

1985-01-01

392

Durability of Oxygen Sensors.  

National Technical Information Service (NTIS)

This report describes the results of dynamometer and vehicle durability testing from a variety of sources, as well as common causes of failures for oxygen sensors. The data indicates that oxygen sensors show low failure rates, even at mileages of 80,000 m...

L. Snapp

1985-01-01

393

Durability of oxygen sensors  

NASA Astrophysics Data System (ADS)

This report describes the results of dynamometer and vehicle durability testing from a variety of sources, as well as common causes of failure for oxygen sensors. The data indicates that oxygen sensors show low failure rates, even at mileages of 80,000 miles and beyond.

Snapp, L.

1985-03-01

394

Reversible Oxygen Electrodes.  

National Technical Information Service (NTIS)

A method for determining the role of H2O2 in oxygen reduction was developed. Preliminary results indicate that H2O2 is a true intermediate in KOH solution and is a product of a parallel reaction in H2SO4 solution. The catalytic activity for the oxygen red...

M. Genshaw V. Brusic A. Damjanovic

1964-01-01

395

Tissue oxygenation with graded dissolved oxygen delivery during cardiopulmonary bypass  

Microsoft Academic Search

Background: Intravascular perfluorochemical emulsions together with a high oxygen tension may increase the delivery of dissolved oxygen to useful levels. The hypothesis of this study is that increasing the dissolved oxygen content of blood with incremental doses of a perfluorochemical emulsion improves tissue oxygenation during cardiopulmonary bypass in a dose-related fashion. Methods and Results: Oxygen utilization was studied in a

William L. Holman; Russell D. Spruell; Edward R. Ferguson; Janice J. Clymer; Walter V. A. Vicente; C. Patrick Murrah; Albert D. Pacifico

1995-01-01

396

Accuracy of oxygen delivery by liquid oxygen canisters  

Microsoft Academic Search

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

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

397

Pumping oxygen into gasoline  

SciTech Connect

To reduce atmospheric concentration of certain pollutants notably carbon monoxide (CO), incompletely combusted hydrocarbons and nitrogen oxides (NOx), EPA as early as January 1988 began testing oxygenated fuels in such cities as Denver and Albuquerque, N.M. The CAA Amendments require using oxygenated gasoline in cities where CO levels exceed National Ambient Air Quality standards. The law, which became effective Nov. 2, affects about 40 urban areas during the winter, when CO levels are higher. Methyl tertiary butyl ether (MTBE), methanol, ethyl tertiary butyl ether (ETBE) or ethanol are used to increase the oxygen content of motor fuel. Do these additives improve air quality The answer is a qualified no. Although oxygenated fuels reduce emissions from older automobiles, there is no statistical improvement in automotive emissions for newer vehicles equipped with three-way catalytic converters. Oxygenates have increased overall fuel cost $14 million annually in the Denver area but have not improved air quality as expected.

Wray, T.K.

1993-10-01

398

Wildlife monitoring, modeling, and fugacity  

SciTech Connect

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.

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

1988-02-01

399

Peroxidase-catalyzed S-oxygenation: Mechanism of oxygen transfer for lactoperoxidase  

SciTech Connect

The mechanism of organosulfur oxygenation by peroxidases (lactoperoxidase (LPX), chloroperoxidase, thyroid peroxidase, and horseradish peroxidase) and hydrogen peroxide was investigated by use of para-substituted thiobenzamides and thioanisoles. The rate constants for thiobenzamide oxygenation by LPX/H{sub 2}O{sub 2} were found to correlate with calculated vertical ionization potentials, suggesting rate-limiting single-electron transfer between LPX compound I and the organosulfur substrate. The incorporation of oxygen from {sup 18}O-labeled hydrogen peroxide, water, and molecular oxygen into sulfoxides during peroxidase-catalyzed S-oxygenation reactions was determined by LC- and GC-MS. All peroxidases tested catalyzed essentially quantitative oxygen transfer from {sup 18}O-labeled hydrogen peroxide into thiobenzamide S-oxide, suggesting that oxygen rebound from the oxoferryl heme is tightly coupled with the initial electron transfer in the active site. Experiments using H{sub 2}{sup 18}O{sub 2}, and H{sub 2}{sup 18}O showed the LPX catalyzed approximately 85,22, and 0% {sup 18}O-incorporation into thioanisole sulfoxide oxygen, respectively. These results are consistent with an active site controlled mechanism in which the protein radical form of LPX compound I is an intermediate in LPX-mediated sulfoxidation reactions.

Doerge, D.R.; Cooray, N.M. (Univ. of Hawaii, Honolulu (United States)); Brewster, M.E. (Pharmatec Inc., Alachua, FL (United States))

1991-09-17

400

Oxidation-Reduction Calculations in the Biochemistry Course  

ERIC Educational Resources Information Center

|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…

Feinman, Richard D.

2004-01-01

401

Predicting oxygen transfer and water flow rate in airlift aerators  

Microsoft Academic Search

Water flow rate, gas-phase holdup, and dissolved oxygen (DO) profiles are measured in a full-scale airlift aerator as a function of applied air flow rate. A model that predicts oxygen transfer based on discrete-bubble principles is applied. The riser DO profiles are used to calculate the initial bubble size. The range of calculated bubble diameters obtained using the model is

Vickie L Burris; Daniel F McGinnis; John C Little

2002-01-01

402

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

Microsoft Academic Search

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

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

2002-01-01

403

Integrated calculator programs for pharmacokinetic calculations.  

PubMed

A package of integrated programs for calculating pharmacokinetic variables and drug-dosing regimens using a hand-held programmable calculator is described. Twelve pharmacokinetic programs, which were based on previously published pharmacokinetic equations, were developed for use in a HP-41C hand-held calculator (Hewlett-Packard). The programs perform, pharmacokinetic calculations for many drugs, including digoxin, theophylline, phenytoin, nd the aminoglycosides. Also programs for ideal body weight, body surface area, and creatinine clearance calculations are included. Eleven of the 12 programs can be stored in the calculator at any time. Values generated in one program are stored in memory registers and can be recalled directly for use in other programs. The calculator has a continuous memory; therefore, all stored data, programs, and functions are maintained when the calculator is turned off. The integrated calculator programs provide a quick and reliable means of applying pharmacokinetic principles to everyday hospital pharmacy practice. PMID:7081256

Robb, R A; Bauer, L A; Koup, J R

1982-05-01

404

Chorangiosis and placental oxygenation.  

PubMed

Chorangiosis is a vascular hyperplasia in the terminal chorionic villi, usually diagnosed histologically using the criteria of Altshuler. Its true etiology has not been fully identified, but chorangiosis has been proposed to result from a longstanding, rather low-grade hypoxia in the placental tissue. To clarify a possible association of placental oxygenation status with the development of chorangiosis, we measured placental tissue oxygen index (TOI) values using near-infrared spectroscopy (NIRS) before delivery and retrospectively compared them to the detection of placental chorangiosis, in a total of 47 (46 singleton and one set of dichorionic diamniotic twins) pregnant women. Small for gestational age (SGA) and/or maternal complications were observed in all cases of placental chorangiosis. Placental TOI values were significantly elevated in cases of chorangiosis. This indicates high oxygen saturation in the intervillous spaces because placental TOI values are expected to represent the oxygenation of maternal blood in the placental tissue. A possible preceding low efficiency of oxygen transfer to the fetal circulation in the villi might not only augment the oxygen saturation of maternal blood in intervillous spaces, but also cause rather low oxygenation in the capillaries of the villi and result in chorangiosis. PMID:19489958

Suzuki, Kazunao; Itoh, Hiroaki; Kimura, Satoshi; Sugihara, Kazuhiro; Yaguchi, Chizuko; Kobayashi, Yukiko; Hirai, Kyuya; Takeuchi, Kinya; Sugimura, Motoi; Kanayama, Naohiro

2009-06-01

405

Oxygen, hypoxia, and stress.  

PubMed

Since cyanobacteria began to photosynthesize and introduce the colorless and odorless gas oxygen into the earth's atmosphere some 2.5 billion years ago, human evolution has been intrinsically linked to this critical molecule. Initially, the electrophilic chemical properties of oxygen rendered it a formidable toxic challenge to organisms; however, eukaryotic cells, following the incorporation of bacterial-derived mitochondria, evolved to make beneficial use of the chemical properties of molecular oxygen as the final electron acceptor in the highly efficient production of cellular energy supplies in the form of adenosine triphosphate. Because of both its necessity for eukaryotic life and its reactive chemical nature, however, a delicate balance exists between the supply of oxygen to a cell/tissue/organism and the beneficial or harmful outcome. In this minireview, we shall discuss the role of oxygen in metabolism with a particular emphasis on outcomes when oxygen supply is significantly altered. Furthermore, we will describe endogenous mechanisms that have evolved to protect cells and tissues during such adverse conditions and may prove useful as novel therapeutic targets in a range of disease states where oxygen-related stress occurs. PMID:17483207

Taylor, Cormac T; Pouyssegur, Jacques

2007-05-04

406

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.

407

Biphasic oxygen kinetics of cellular respiration and linear oxygen dependence of antimycin A inhibited oxygen consumption.  

PubMed

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 basis for the maintenance of a high aerobic scope at physiological low-oxygen levels, whereas further pronounced depression of oxygen pressure induces energetic stress under hypoxia. PMID:12241081

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

2002-01-01

408

Why Do I Need Oxygen Therapy?  

MedlinePLUS

... delivered by three types of devices: oxygen concentrator, liquid system or oxygen in a metal cylinder. What ... low concentrations of oxygen being delivered. What is liquid oxygen? Liquid oxygen is oxygen that is cooled ...

409

Excitation of the [sup 3][ital P][sub [ital J]=0,1,2] fine-structure levels of atomic oxygen in collisions with oxygen atoms  

SciTech Connect

A fully quantal calculation of the excitation cross sections for the fine-structure levels of ground-state atomic oxygen, in collisions with oxygen atoms at low energies, is presented. The results are compared with the cross sections obtained in a previous calculation.

Zygelman, B. (Department of Physics, University of Nevada at Las Vegas, Las Vegas, Nevada 89154 (United States)); Dalgarno, A. (Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States)); Sharma, R.D. (Optical Environment Division, Phillips Laboratory, 29 Randolph Road, Hanscom Air Force Base, Massachusetts 01731-3010 (United States))

1994-11-01

410

Vibrations of the Interstitial Oxygen Pairs in Silicon  

NASA Astrophysics Data System (ADS)

First-principles methods are used to calculate the structures and local vibrational modes of interstitial oxygen pairs in silicon. The staggered Oi-Si-Oi and skewed Oi-Si-Si-Oi structures are nearly degenerate in energy. The calculated local vibration frequencies and their pure and mixed 18O-->16O isotopic shifts agree closely with experiments: the highest frequency is assigned to the skewed and the four lower ones to the staggered structure. This result may clear up the controversy of oxygen dimers in silicon, and also suggests a mechanism for fast oxygen diffusion.

Pesola, M.; von Boehm, J.; Nieminen, R. M.

1999-05-01

411

[The kinetics of oxygen transport by the blood].  

PubMed

A method for calculation of oxygen metabolism kinetics in vivo for different blood pH and for different inhaled air pressure is proposed. It is based on joint solution of equations of oxygen balance in lungs and in capillaries of oxygen-consuming tissues. All calculations were carried out within the physiological range of the above parameters. The value of maximum physical load was estimated for each set of the parameters. This load was evaluated in respect to the maximal oxygen consumption possible under conditions selected. Only data borrowed from normal physiology were used in calculations. It was shown that oxyhemoglobin dissociation curve shifts (for example, caused by blood pH deviation from its norm) does not have substantial influence on the organism ability to produce work, on its supplement with the oxygen, and can not cause pathologies at acidosis and alkalosis. This new result was obtained due to adoption of strict equality of the oxygen flows absorbed by blood in the lungs and of the oxygen given back by the blood in capillaries of the oxygen-consuming tissues. PMID:8160489

Fok, M V; Zaritski?, A R; Prokopenko, G A; Lobchenko, I M

412

Medical Oxygen Safety  

MedlinePLUS

... Medical Oxygen Medical Safety Post “No Smoking” “No Open Flames” in and outside the home to remind people not to smoke. Your Source for SAFETY Information NFPA Public Education Division | www. ...

413

Designing blood oxygenators.  

PubMed

Extracorporeal blood oxygenators are used to provide cardiopulmonary support during open heart surgery. In the study reported here, mass transfer correlations were determined for commercially available blood oxygenators. Two configurations used commercially, flow outside and across bundles of hollow fibers and flow in thin channels between parallel flat sheet membranes, were investigated. Water and glycerol/water mixtures were used as a substitute for blood. Diffusion of oxygen into and out of these solutions was studied. For flow across bundles of hollow fibers, the mass transfer correlations derived here are in agreement with analogous correlations for crossflow heat exchangers. However, for flow in thin channels, the rate of mass transfer is often less than predicted from theory. This compromised mass transfer can be explained by considering slight variations in the thickness of the blood flow channels. The mass transfer correlations developed here could be used to design better blood oxygenators. PMID:12783841

Wickramasinghe, S R; Goerke, A R; Garcia, J D; Han, Binbing

2003-03-01

414

Oxygen and Biological Evolution.  

ERIC Educational Resources Information Center

|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)|

Baugh, Mark A.

1990-01-01

415

OXYGEN TRANSPORT CERAMIC MEMBRANES  

SciTech Connect

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.

Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

2002-07-01

416

Hyperbaric oxygen therapy  

MedlinePLUS

... units may be available in outpatient center. The air pressure inside a hyperbaric oxygen chamber is about two and a half times greater than the normal pressure in the ... Air or gas embolism Bone infections ( osteomyelitis ) that have ...

417

Collect Oxygen Over Water  

NSDL National Science Digital Library

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).

Ragan, Sean M.

2011-01-01

418

Oxygen from lunar regolith  

NASA Astrophysics Data System (ADS)

We summarise the various methods that have been explored for the production of oxygen from lunar materials. Our main focus in this paper is on a novel approach developed at the University of Cambridge that employs molten salt electrochemistry to achieve the combined winning of oxygen and metal from solid lunar materials of varying composition. This makes the Cambridge process attractive because it will work equally well in mare as in highland regions.

Schwandt, C.; Hamilton, J. A.; Fray, D. J.; Crawford, I. A.

419

Oxygen Movement in Seagrasses  

Microsoft Academic Search

Seagrasses are, like all vascular plants, obligate aerobes, which require a continuous supply of oxygen to sustain aerobic\\u000a metabolism of both above- and below-ground tissues. Compared to their leaves, seagrass roots and rhizomes may experience oxygen\\u000a deprivation for shorter periods, but these below-ground tissues exhibit physiological adaptations which allow them to rely\\u000a temporarily on anaerobic fermentative metabolism (Pregnall et al.,

Jens Borum; Kaj Sand-Jensen; Thomas Binzer; Ole Pedersen; Tina Maria Greve

420

The compositional evolution of differentiated liquids from the Skaergaard Layered Series as determined by geochemical thermometry  

Microsoft Academic Search

Based on the COMAGMAT-3.65 crystallization model a set of phase equilibria calculations (called geochemical thermometry) have been conducted at P=1 kbar and closed conditions with respect to oxygen for 65 rocks representing the principle units of the Layered Series of the Skaergaard intrusion. It allowed us to define the range of initial temperatures (1145 to 1085 C) and oxygen fugacities

A. A. Ariskin

2003-01-01

421

Interactions of oxygen with Zr(0001)  

SciTech Connect

Interaction of oxygen with Zr(0001) have been studied using low energy electron diffraction (LEED), work function ([Delta][phi]), static and dynamic secondary ion mass spectrometry (SSIMS, DSIMS), thermal desorption spectroscopy (TDS), Auger electron spectroscopy (AES) and nuclear reaction analysis (NRA). The initial sticking coefficient of oxygen is close to unity up to [approximately]0.75 ML at 90, 293 and 473 K. Oxygen chemisorption is disordered at room temperature and below. Heating the disordered surface to [approximately]473 K causes all oxygen to move to subsurface sites. A (1x2) ordered oxygen underlayer is formed consisting of three rotated domains of (1x2) superstructure with the oxygen atoms located between the first and second planes of zirconium atoms. This structure is stable up to about 573 K, above which temperature oxygen diffuses into the bulk. AES measurements employing oxide and metal signals were used to model the growth of oxide which was found to be temperature dependent. Both NRA and AES indicate linear oxygen uptake kinetics at 90 K with abrupt passivation as the limiting thickness is reached. SSIMS ion yield data taken during the oxidation of Zr(0001) at 90, 293 and 473 K was interpretable in the context of the oxygen coverage. Dissolution into the bulk of the saturated oxide layer grown at 90 K appears to occur by an island-type mechanism rather than layer-by-layer dissolution from the oxide-metal interface. Large [Delta][phi] changes that occur upon oxidation at 90 K and temperature ramping of the saturated oxide to 300 K are attributable to reversible molecular oxygen adsorption on the oxide. The diffusion of oxygen normal to the [0001] plane of zirconium has been measured by AES: D[sub 0] = (4.14.[+-]1.92) x 10[sup [minus]2] cm[sup [minus]2] s[sup [minus]1] and E[sub a]= 199.1 [+-]2.6 kJ mol[sup [minus]1]. The fundamental vibrational frequency for the [alpha]-Zr lattice was calculated to be (6.3 [+-] 2.9) x 10[sup 13]s[sup [minus]1].

Flinn, B.J.

1992-01-01

422

Vintage Calculators Web Museum  

NSDL National Science Digital Library

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.

Tout, Nigel

423

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

Microsoft Academic Search

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

J. A. Tomaszek; E. Czerwieniec

2003-01-01

424

Oxygen electrode in molten carbonate fuel cells  

NASA Astrophysics Data System (ADS)

Effects of partial pressure of oxygen and temperature on oxygen reduction kinetics on a submerged gold electrode in lithium carbonate melt were investigated using cyclic voltammetry and impedance analysis. Cyclic voltammetry measurements show that the peroxide reduction reaction in Li2CO3 melt is reversible up to 200 mV/s. The impedance analysis was carried out using a Complex Nonlinear Least Square (CNLS) parameter estimation program based upon the Randles-Ershler equivalent circuit. This analysis estimated electrode kinetics and mass transfer related parameters such as charge transfer resistance and Warburg coefficient. The mass transfer related parameters obtained from cyclic voltammetry and impedance analysis show good agreement. The oxygen reaction orders for mass transfer parameter and exchange current density at 800 C were calculated to be 0.5 and 0.377 respectively; these values are consistent with the peroxide mechanism.

Dave, B. B.; Adanuvor, P. K.; Enayetullah, M. A.; White, R. E.; Srinivasan, S.; Appleby, A. J.

425

Activation of molecular oxygen in trifluoroacetic acid  

NASA Astrophysics Data System (ADS)

The interaction of molecular oxygen with aqueous trifluoroacetic acid (TFA) led to an increase in pH. This effect was explained by a decrease in the concentration of the protonated CF3CO2H{2/+} and H3O+ species after oxygen was fed in the reactor. Quantum-chemical calculations show that a radical pair can be formed in an activation-free exothermal reaction involving the radical residue of the acid, the CF3CO2H{2/+}...3O2...CF3CO{2/-} peroxide radical, and the acid molecule in the CF3C{2/·}...HOO· collision complex. It was assumed that the activation of molecular oxygen in aqueous TFA solutions, providing the activity of the system in oxidations of various organic and inorganic substrates, is related to the formation of peroxide radicals in them.

Vishnetskaya, M. V.; Vasin, A. V.; Solkan, V. N.; Zhidomirov, G. M.; Mel'Nikov, M. Ya.

2010-11-01

426

EXPERIMENTAL STUDY OF CONCENTRATION DEPENDENCE OF Ta2O5 SOLUBILITY IN THE ALKALINE SOLUTIONS AT T=550 o C, P=1000 BAR AND LOW OXYGEN FUGACITY (Co-CoO BUFFER)  

Microsoft Academic Search

To estimate quantitatively a possible role of postmagmatic processes in genesis of rare-metal de- posits of tantalum and niobium we performed systematic experimental investigations on mineral solu- bility of Ta and Nb under hydrothermal conditions, because the available experimental data are not enough to solve this problem. Earlier we investigated Ta oxide solubility in fluoride and chloride solu- tions what

IEM RAS

427

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.  

National Technical Information Service (NTIS)

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. That paper was followed by several on QUE94201 melt composition and specifically on Cr,...

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

2013-01-01

428

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  

Microsoft Academic Search

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} conditions. D{sub Eu} augite\\/melt shows a steady increase with f{sub O} 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

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

2010-01-01

429

42 CFR 414.226 - Oxygen and oxygen equipment.  

Code of Federal Regulations, 2010 CFR

...Health 3 2009-10-01 2009-10-01 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...

2009-10-01

430

42 CFR 414.226 - Oxygen and oxygen equipment.  

Code of Federal Regulations, 2010 CFR

...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...

2010-10-01

431

Alphalike calculations with MCNP  

SciTech Connect

Alpha (time-absorption eigenvalue) calculations are not an explicit calculational option in MCNP. However, alpha-like calculations can easily be performed with MCNP using the KCODE option with neutron energy or time cutoffs. These alphalike calculations are described and tested here. Approximate alpha flux distributions may easily be calculated by this method.

Parsons, D.K. [Los Alamos National Lab., NM (United States)

1997-12-01

432

Regulation of tissue oxygen levels in the mammalian lens.  

PubMed

Opacification of the lens nucleus is a major cause of blindness and is thought to result from oxidation of key cellular components. Thus, long-term preservation of lens clarity may depend on the maintenance of hypoxia in the lens nucleus. We mapped the distribution of dissolved oxygen within isolated bovine lenses and also measured the rate of oxygen consumption (QO2) by lenses, or parts thereof. To assess the contribution of mitochondrial metabolism to the lens oxygen budget, we tested the effect of mitochondrial inhibitors on (QO2) and partial pressure of oxygen (PO2). The distribution of mitochondria was mapped in living lenses by 2-photon microscopy. We found that a steep gradient of PO2 was maintained within the tissue, leading to PO2 < 2 mmHg in the core. Mitochondrial respiration accounted for approximately 90% of the oxygen consumed by the lens; however, PO2 gradients extended beyond the boundaries of the mitochondria-containing cell layer, indicating the presence of non-mitochondrial oxygen consumers. Time constants for oxygen consumption in various regions of the lens and an effective oxygen diffusion coefficient were calculated from a diffusion-consumption model. Typical values were 3 x 10(-5) cm(2) s(-1) for the effective diffusion coefficient and a 5 min time constant for oxygen consumption. Surprisingly, the calculated time constants did not differ between differentiating fibres (DF) that contained mitochondria and mature fibres (MF) that did not. Based on these parameters, DF cells were responsible for approximately 88% of lens oxygen consumption. A modest reduction in tissue temperature resulted in a marked decrease in (QO2) and the subsequent flooding of the lens core with oxygen. This phenomenon may be of clinical relevance because cold, oxygen-rich solutions are often infused into the eye during intraocular surgery. Such procedures are associated with a strikingly high incidence of postsurgical nuclear cataract. PMID:15272034

McNulty, Richard; Wang, Huan; Mathias, Richard T; Ortwerth, Beryl J; Truscott, Roger J W; Bassnett, Steven

2004-07-22

433

Oxygen consumption in heifers three months of age related to lactation milk energy.  

PubMed

Calibration techniques were developed for a modified commercial oxygen consumption computer. Oxygen consumption over 5 min by 130 3-mo-old dairy calves was measured 3 h after feeding. Subsequently, Estimated Transmitting Abilities were used to calculate the production potential for lactation milk energy (kcal/305-day lactation) for 88 of the animals. Correlations between lactation milk energy and oxygen consumption or oxygen consumption corrected for weight of calf were calculated by breed. Breed correlations were tested for homogeneity and pooled. The correlation coefficient between oxygen consumption and lactation milk energy was .20 with a 95% confidence interval of -.02 to .40. PMID:7198658

Congleton, W R; Coffin, D R; Rowe, R J; Sniffen, C J; Dickey, H C; Musgrave, S D; Leonard, H A

1981-09-01

434

OXYGEN POISONING IN MAMMALS  

PubMed Central

1. Oxygen in concentrations of over 70 per cent of an atmosphere is poisonous to dogs, rabbits, guinea pigs and mice. 2. The poisonous effects manifest themselves in drowsiness, anorexia, loss of weight, increasing dyspnea, cyanosis and death from oxygen want. 3. The cause of oxygen want is a destructive lesion of the lungs. 4. The lesion may be characterized grossly as an hemorrhagic edema. Microscopically there is to be seen in varying degrees of intensity (a) capillary engorgement with hemorrhage, (b) the presence of interstitial and intraalveolar serum, (c) hypertrophy and desquamation of alveolar cells, (d) interstitial and alveolar infiltration of mononuclear cells. 5. The type of tissue reaction is not characteristic of an infectious process and no organisms have been recovered at autopsy from the heart's blood or from lung puncture. 6. The poisonous effects of inhalations of oxygen-rich mixtures do not appear to be related to impurities in the oxygen, nor are they related to faulty ventilation, excessive moisture or increased carbon dioxide in the atmosphere of the chambers in which the experimental animals were confined.

Binger, Carl A. L.; Faulkner, James M.; Moore, Richmond L.

1927-01-01

435

Optical oxygen concentration monitor  

DOEpatents

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.

Kebabian, P.

1997-07-22

436

Dissolved oxygen and fish behavior  

Microsoft Academic Search

Synopsis This essay reviews the behavioral responses of fish to reduced levels of dissolved oxygen from the perspective of optimization theory as used in contemporary behavioral ecology. A consideration of oxygen as a resource suggests that net oxygen gain per unit of energy expenditure will be the most useful currency for ecological models of breathing. In the process of oxygen

Donald L. Kramer

1987-01-01

437

The Empirical Calculation of the Fugacities in Gaseous Mixtures. II. Its Relation to the Tangents on Certain Thermodynamic Diagrams. Approximate Equations For Some Important Thermodynamic Properties of Gas Mixtures  

Microsoft Academic Search

The thermodynamic account of the behavior of mixtures of real gases at constant temperature may be resolved into two problems: (1) The p-v-T relationships for pure gases, as embraced in equations of state; and (2) The behavior of gases on mixing at constant temperature and volume, as expressed for example by the excess v¯1-v1 of the partial molal volume of

Louis J. Gillespie

1929-01-01

438

Monolithic solid electrolyte oxygen pump  

DOEpatents

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

Fee, Darrell C. (2529 Lee St., Woodridge, IL 60517); Poeppel, Roger B. (67 Stephanie La., Glen Ellyn, IL 60137); Easler, Timothy E. (564 N. Pinecrest, Bolingbrook, IL 60439); Dees, Dennis W. (6224 Middaugh Ave., Downers Grove, IL 60517)

1989-01-01

439

Role of oxygen-related defects in hafnia  

NASA Astrophysics Data System (ADS)

Hafnia has recently received much attention because of its potential application as high-k dielectric material replacing silica in microelectronic devices. Point defects in hafnia - in particular oxygen vacancies and interstitials - can play an important role as traps or sources of fixed charge. In this study, we perform electronic structure calculations on oxygen-related defects in monoclinic hafnia using a combined density functional theory (DFT) and GW formalism. We have previously shown that upon including quasiparticle defect levels and the appropriate electrostatic corrections within a supercell calculation, this formalism corrects for the error in calculating formation energy and charge transition levels using standard DFT. In this study, we calculate the formation energy of these defects as a function of the Fermi level and the chemical potential of oxygen to determine which of these defects are most stable.

Jain, Manish; Chelikowsky, James R.; Louie, Steven G.

2012-02-01

440

Theory of negative corona in oxygen  

Microsoft Academic Search

Theoretical predictions are given of the development of the current and the distributions of charge and electric field in negative corona, or Trichel current pulses [G. W. Trichel, Phys. Rev. 54, 1078 (1938)], in oxygen at a pressure of 6.67 kPa (50 Torr). For a 10-mm-diam negative sphere located 20 mm from a positive plane, the calculated current pulse has

R. Morrow

1985-01-01

441

The oxygen enrichment of the Galaxy  

Microsoft Academic Search

Oxygen-to-hydrogen ratios are calculated for the 97 planetary nebulae for which there are sufficient data and for which the correction for unobserved ionization states is not too large. The ratios are strongly correlated with population type. Almost all planetaries with absolute LSR radial velocity greater than about 85 km\\/s and distance from the galactic plane greater than 1 kpc have

J. B. Kaler

1980-01-01

442

The oxygen enrichment of the galaxy  

Microsoft Academic Search

Oxygen-to-hydrogen ratios are calculated for the 97 planetary nebulae for which there are sufficient data and for which the correction for unobserved ionization states is not too large. As a part of this study, emission-line fluxes are presented for 19 planetaries. The ratios are strongly correlated with population type. Almost all planetaries with absolute LSR radial velocity greater than about

J. B. Kaler

1980-01-01

443

Interactions of Oxygen and Hydrogen on Pd(111) surface  

SciTech Connect

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).

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

2008-06-25