High rate reactive sputtering of MoN(x) coatings

NASA Technical Reports Server (NTRS)

Rudnik, Paul J.; Graham, Michael E.; Sproul, William D.

1991-01-01

High rate reactive sputtering of MoN(x) films was performed using feedback control of the nitorgen partial pressure. Coatings were made at four different target powers: 2.5, 5.0, 7.5 and 10 kW. No hysteresis was observed in the nitrogen partial pressure vs. flow plot, as is typically seen for the Ti-N system. Four phases were determined by X-ray diffraction: molybdenum, Mo-N solid solution, Beta-Mo2N and gamma-Mo2N. The hardness of the coatings depended upon composition, substrate bias, and target power. The phases present in the hardest films differed depending upon deposition parameters. For example, the Beta-Mo2N phase was hardest (load 25 gf) at 5.0 kW with a value of 3200 kgf/sq mm, whereas the hardest coatings at 10 kW were the gamma-Mo2N phase (3000 kgf/sq mm). The deposition rate generally decreased with increasing nitrogen partial pressure, but there was a range of partial pressures where the rate was relatively constant. At a target power of 5.0 kW, for example, the deposition rates were 3300 A/min for a N2 partial pressure of 0.05 - 1.0 mTorr.

Lunar mass spectrometer test program

NASA Technical Reports Server (NTRS)

Torney, F. L.; Dobrott, J. R.

1972-01-01

The procedures are described along with results obtained in a test program conducted to demonstrate the performance of a candidate lunar mass spectrometer. The instrument was designed to sample and measure gases believed to exist in the lunar atmosphere at the surface. The subject instrument consists of a cold cathode ion source, a small quadrupole mass analyzer and an off axis electron multiplier ion counting detector. The major program emphasis was placed on demonstrating instrument resolution, sensitivity and S/N ratio over the mass range 0-150 amu and over a partial pressure range from 10 to the minus 9th power to 10 to the minus 13th power torr. Ultrahigh vacuum tests were conducted and the minimum detectable partial pressure for neon, argon, krypton and xenon was successfully determined for the spectrometer using isotopes of these gases. With the exception of neon, the minimum detectable partial pressure is approximately 4 x 10 to the minus 14th power torr for the above gases.

Solubilities of carbon dioxide in aqueous potassium carbonate solutions mixed with physical solvents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, S.B.; Lee, H.; Lee, K.H.

1998-09-01

The removal of acidic gases such as CO{sub 2}, H{sub 2}S, and COS from gas streams is a very important operation for petrochemical, oil refineries, ammonia manufacture, coal gasification, and natural gas purification plants. Here, the solubilities of carbon dioxide in aqueous potassium carbonate (K{sub 2}CO{sub 3}) solutions mixed with physical solvents were measured at 298.2 and 323.2 K with a CO{sub 2} partial-pressure range of 5 kPa to 2 MPa. 1,2-propanediol and propylene carbonate were selected as physical solvents. The aqueous solutions treated in this study were 5 mass% K{sub 2}CO{sub 3}-15 mass% 1,2-propanediol and propylene carbonate were selectedmore » as physical solvents. The aqueous solutions treated in this study were 5 mass% K{sub 2}CO{sub 3}-15 mass% propylene carbonate. The experimental solubility results were presented by the mole ratio of CO{sub 2} and K{sub 2}CO{sub 3} contained in the liquid mixture. The addition of 1,2-propanediol to 5 mass% K{sub 2}CO{sub 3} solution lowered the solubility of CO{sub 2} at constant temperature and pressure conditions when CO{sub 2} partial-pressure range of 5 kPa to 2 MPa. In the case of propylene carbonate the addition of propylene carbonate increased the experimental solubilities in the region of low CO{sub 2} partial pressures and decreased as the CO{sub 2} partial pressure was increased above atmospheric. The solubilities of CO{sub 2} decreased with increasing temperature in the range of 298.2 to 323.2 K.« less

A Double-Blinded, Randomized Comparison of Medetomidine-Tiletamine-Zolazepam and Dexmedetomidine-Tiletamine-Zolazepam Anesthesia in Free-Ranging Brown Bears (Ursus Arctos)

PubMed Central

Cattet, Marc; Zedrosser, Andreas; Stenhouse, Gordon B.; Küker, Susanne; Evans, Alina L.; Arnemo, Jon M.

2017-01-01

We compared anesthetic features, blood parameters, and physiological responses to either medetomidine-tiletamine-zolazepam or dexmedetomidine-tiletamine-zolazepam using a double-blinded, randomized experimental design during 40 anesthetic events of free-ranging brown bears (Ursus arctos) either captured by helicopter in Sweden or by culvert trap in Canada. Induction was smooth and predictable with both anesthetic protocols. Induction time, the need for supplemental drugs to sustain anesthesia, and capture-related stress were analyzed using generalized linear models, but anesthetic protocol did not differentially affect these variables. Arterial blood gases and acid-base status, and physiological responses were examined using linear mixed models. We documented acidemia (pH of arterial blood < 7.35), hypoxemia (partial pressure of arterial oxygen < 80 mmHg), and hypercapnia (partial pressure of arterial carbon dioxide ≥ 45 mmHg) with both protocols. Arterial pH and oxygen partial pressure were similar between groups with the latter improving markedly after oxygen supplementation (p < 0.001). We documented dose-dependent effects of both anesthetic protocols on induction time and arterial oxygen partial pressure. The partial pressure of arterial carbon dioxide increased as respiratory rate increased with medetomidine-tiletamine-zolazepam, but not with dexmedetomidine-tiletamine-zolazepam, demonstrating a differential drug effect. Differences in heart rate, respiratory rate, and rectal temperature among bears could not be attributed to the anesthetic protocol. Heart rate increased with increasing rectal temperature (p < 0.001) and ordinal day of capture (p = 0.002). Respiratory rate was significantly higher in bears captured by helicopter in Sweden than in bears captured by culvert trap in Canada (p < 0.001). Rectal temperature significantly decreased over time (p ≤ 0.05). Overall, we did not find any benefit of using dexmedetomidine-tiletamine-zolazepam instead of medetomidine-tiletamine-zolazepam in the anesthesia of brown bears. Both drug combinations appeared to be safe and reliable for the anesthesia of free-ranging brown bears captured by helicopter or by culvert trap. PMID:28118413

Modeling the Effect of Modified Atmospheres on Conidial Germination of Fungi from Dairy Foods

PubMed Central

Nguyen Van Long, Nicolas; Vasseur, Valérie; Couvert, Olivier; Coroller, Louis; Burlot, Marion; Rigalma, Karim; Mounier, Jérôme

2017-01-01

Modified atmosphere packaging (MAP) is commonly applied to extend food shelf-life. Despite growth of a wide variety of fungal contaminants has been previously studied in relation to modified-atmospheres, few studies aimed at quantifying the effects of dioxygen (O2) and carbon dioxide (CO2) partial pressures on conidial germination in solid agar medium. In the present study, an original culture method was developed, allowing microscopic monitoring of conidial germination under modified-atmospheres in static conditions. An asymmetric model was utilized to describe germination kinetics of Paecilomyces niveus, Mucor lanceolatus, Penicillium brevicompactum, Penicillium expansum, and Penicillium roquefoti, using two main parameters, i.e., median germination time (τ) and maximum germination percentage (Pmax). These two parameters were subsequently modeled as a function of O2 partial pressure ranging from 0 to 21% and CO2 partial pressure ranging from 0.03 to 70% (8 tested levels for both O2 and CO2). Modified atmospheres with residual O2 or CO2 partial pressures below 1% and up to 70%, respectively, were not sufficient to totally inhibit conidial germination,. However, O2 levels < 1% or CO2 levels > 20% significantly increased τ and/or reduced Pmax, depending on the fungal species. Overall, the present method and results are of interest for predictive mycology applied to fungal spoilage of MAP food products. PMID:29163403

Oxygen Partial Pressure Is a Rate-Limiting Parameter for Cell Proliferation in 3D Spheroids Grown in Physioxic Culture Condition.

PubMed

Gomes, Aurélie; Guillaume, Ludivine; Grimes, David Robert; Fehrenbach, Jérôme; Lobjois, Valérie; Ducommun, Bernard

2016-01-01

The in situ oxygen partial pressure in normal and tumor tissues is in the range of a few percent. Therefore, when studying cell growth in 3D culture systems, it is essential to consider how the physiological oxygen concentration, rather than the one in the ambient air, influences the proliferation parameters. Here, we investigated the effect of reducing oxygen partial pressure from 21% to 5% on cell proliferation rate and regionalization in a 3D tumor spheroid model. We found that 5% oxygen concentration strongly inhibited spheroid growth, changed the proliferation gradient and reduced the 50% In Depth Proliferation index (IDP50), compared with culture at 21% oxygen. We then modeled the oxygen partial pressure profiles using the experimental data generated by culturing spheroids in physioxic and normoxic conditions. Although hypoxia occurred at similar depth in spheroids grown in the two conditions, oxygen partial pressure was a major rate-limiting factor with a critical effect on cell proliferation rate and regionalization only in spheroids grown in physioxic condition and not in spheroids grown at atmospheric normoxia. Our findings strengthen the need to consider conducting experiment in physioxic conditions (i.e., tissue normoxia) for proper understanding of cancer cell biology and the evaluation of anticancer drugs in 3D culture systems.

Petrologic Constraints on Magma Plumbing Systems Beneath Hawaiian Volcanoes

NASA Astrophysics Data System (ADS)

Li, Y.; Peterman, K. J.; Scott, J. L.; Barton, M.

2016-12-01

We have calculated the pressures of partial crystalliztion of basaltic magmas from Hawaii using a petrological method. A total of 1576 major oxide analyses of glasses from four volcanoes (Kilauea and the Puna Ridge, Loihi, Mauna Loa, and Mauna Kea, on the Big Island) were compiled and used as input data. Glasses represent quenched liquid compositions and are ideal for calculation of pressures of partial crystallization. The results were filtered to exclude samples that yielded unrealistic high errors associated with the calculated pressure or negative value of pressure, and to exclude samples with non-basaltic compositions. Calculated pressures were converted to depths of partial crystallization. The majority (68.2%) of pressures for the shield-stage subaerial volcanoes Kilauea, Mauna Loa, and Mauna Kea, fall in the range 0-140 MPa, corresponding to depths of 0-5 km. Glasses from the Puna Ridge yield pressures ranging from 18 to 126 MPa and are virtually identical to pressures determined from glasses from Kilauea (0 to 129 MPa). These results are consistent with the presence of magma reservoirs at depths of 0-5 km beneath the large shield volcanoes. The inferred depth of the magma reservoir beneath the summit of Kilauea (average = 1.8 km, maximum = 5 km) agrees extremely well with depths ( 2-6 km) estimated from seismic studies. The results for Kilauea and Mauna Kea indicate that significant partial crystallization also occurs beneath the summit reservoirs at depths up to 11 km. These results are consistent with seismic evidence for the presence of a magma reservoir at 8-11 km beneath Kilauea at the base of the volcanic pile. The results for Loihi indicate crystallization at higher average pressures (100-400 MPa) and depths (3-14 km) than the large shield volcanoes, suggesting that the plumbing system is not yet fully developed, and that the Hawaiian volcanic plumbing systems evolve over time.

Thermodynamic models for bounding pressurant mass requirements of cryogenic tanks

NASA Technical Reports Server (NTRS)

Vandresar, Neil T.; Haberbusch, Mark S.

1994-01-01

Thermodynamic models have been formulated to predict lower and upper bounds for the mass of pressurant gas required to pressurize a cryogenic tank and then expel liquid from the tank. Limiting conditions are based on either thermal equilibrium or zero energy exchange between the pressurant gas and initial tank contents. The models are independent of gravity level and allow specification of autogenous or non-condensible pressurants. Partial liquid fill levels may be specified for initial and final conditions. Model predictions are shown to successfully bound results from limited normal-gravity tests with condensable and non-condensable pressurant gases. Representative maximum collapse factor maps are presented for liquid hydrogen to show the effects of initial and final fill level on the range of pressurant gas requirements. Maximum collapse factors occur for partial expulsions with large final liquid fill fractions.

Oxygen partial pressure dependence of thermoelectric power factor in polycrystalline n-type SrTiO3: Consequences for long term stability in thermoelectric oxides

NASA Astrophysics Data System (ADS)

Sharma, Peter A.; Brown-Shaklee, Harlan J.; Ihlefeld, Jon F.

2017-04-01

The Seebeck coefficient and electrical conductivity have been measured as functions of oxygen partial pressure over the range of 10-22 to 10-1 atm at 1173 K for a 10% niobium-doped SrTiO3 ceramic with a grain size comparable to the oxygen diffusion length. Temperature-dependent measurements performed from 320 to 1275 K for as-prepared samples reveal metallic-like conduction and good thermoelectric properties. However, upon exposure to progressively increasing oxygen partial pressure, the thermoelectric power factor decreased over time scales of 24 h, culminating in a three order of magnitude reduction over the entire operating range. Identical measurements on single crystal samples show negligible changes in the power factor so that the instability of ceramic samples is primarily tied to the kinetics of grain boundary diffusion. This work provides a framework for understanding the stability of thermoelectric properties in oxides under different atmospheric conditions. The control of the oxygen atmosphere remains a significant challenge in oxide thermoelectrics.

Comparing CT perfusion with oxygen partial pressure in a rabbit VX2 soft-tissue tumor model.

PubMed

Sun, Chang-Jin; Li, Chao; Lv, Hai-Bo; Zhao, Cong; Yu, Jin-Ming; Wang, Guang-Hui; Luo, Yun-Xiu; Li, Yan; Xiao, Mingyong; Yin, Jun; Lang, Jin-Yi

2014-01-01

The aim of this study was to evaluate the oxygen partial pressure of the rabbit model of the VX2 tumor using a 64-slice perfusion CT and to compare the results with that obtained using the oxygen microelectrode method. Perfusion CT was performed for 45 successfully constructed rabbit models of a VX2 brain tumor. The perfusion values of the brain tumor region of interest, the blood volume (BV), the time to peak (TTP) and the peak enhancement intensity (PEI) were measured. The results were compared with the partial pressure of oxygen (PO2) of that region of interest obtained using the oxygen microelectrode method. The perfusion values of the brain tumor region of interest in 45 successfully constructed rabbit models of a VX2 brain tumor ranged from 1.3-127.0 (average, 21.1 ± 26.7 ml/min/ml); BV ranged from 1.2-53.5 ml/100g (average, 22.2 ± 13.7 ml/100g); PEI ranged from 8.7-124.6 HU (average, 43.5 ± 28.7 HU); and TTP ranged from 8.2-62.3 s (average, 38.8 ± 14.8 s). The PO2 in the corresponding region ranged from 0.14-47 mmHg (average, 16 ± 14.8 mmHg). The perfusion CT positively correlated with the tumor PO2, which can be used for evaluating the tumor hypoxia in clinical practice.

Measurements of Pressure Distributions and Force Coefficients in a Squeeze Film Damper. Part 2: Partially Sealed Configuration

NASA Technical Reports Server (NTRS)

Jung, S. Y.; Sanandres, Luis A.; Vance, J. M.

1991-01-01

Experimental results from a partially sealed squeeze film damper (SFD) test rig, executing a circular centered orbit are presented and discussed. A serrated piston ring is installed at the damper exit. This device involves a new sealing concept which produces high damping values while allowing for oil flow to cool the damper. In the partially sealed damper, large cavitation regions are observed in the pressure fields at orbit radii epsilon equals 0.5 and epsilon equals 0.8. The cavitated pressure distributions and the corresponding force coefficients are compared with a cavitated bearing solution. The experimental results show the significance of fluid inertia and vapor cavitation in the operation of squeeze film dampers. Squeeze film Reynolds numbers tested reach up to Re equals 50, spanning the range of contemporary applications.

Oxygen Partial Pressure Is a Rate-Limiting Parameter for Cell Proliferation in 3D Spheroids Grown in Physioxic Culture Condition

PubMed Central

Gomes, Aurélie; Guillaume, Ludivine; Grimes, David Robert; Fehrenbach, Jérôme; Lobjois, Valérie; Ducommun, Bernard

2016-01-01

The in situ oxygen partial pressure in normal and tumor tissues is in the range of a few percent. Therefore, when studying cell growth in 3D culture systems, it is essential to consider how the physiological oxygen concentration, rather than the one in the ambient air, influences the proliferation parameters. Here, we investigated the effect of reducing oxygen partial pressure from 21% to 5% on cell proliferation rate and regionalization in a 3D tumor spheroid model. We found that 5% oxygen concentration strongly inhibited spheroid growth, changed the proliferation gradient and reduced the 50% In Depth Proliferation index (IDP50), compared with culture at 21% oxygen. We then modeled the oxygen partial pressure profiles using the experimental data generated by culturing spheroids in physioxic and normoxic conditions. Although hypoxia occurred at similar depth in spheroids grown in the two conditions, oxygen partial pressure was a major rate-limiting factor with a critical effect on cell proliferation rate and regionalization only in spheroids grown in physioxic condition and not in spheroids grown at atmospheric normoxia. Our findings strengthen the need to consider conducting experiment in physioxic conditions (i.e., tissue normoxia) for proper understanding of cancer cell biology and the evaluation of anticancer drugs in 3D culture systems. PMID:27575790

Infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide.

PubMed

Kong, Chang Yi; Siratori, Tomoya; Funazukuri, Toshitaka; Wang, Guosheng

2014-10-03

The effects of temperature and density on retention of platinum(II) 2,4-pentanedionate in supercritical fluid chromatography were investigated at temperatures of 308.15-343.15K and pressure range from 8 to 40MPa by the chromatographic impulse response method with curve fitting. The retention factors were utilized to derive the infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide. The determined partial molar volumes were small and positive at high pressures but exhibited very large and negative values in the highly compressible near critical region of carbon dioxide. Copyright © 2014 Elsevier B.V. All rights reserved.

Experimental study of catalytic hydrogenation by using an in-situ hydrogen measuring technique. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiang, S.H.; Klinzing, G.E.; Cheng, Y.S.

1984-12-01

An in-situ technique for measuring hydrogen concentration (partial pressure) had been previously used to measure static properties (hydrogen solubilities, vapor pressures of hydrocarbons, etc.). Because of its good precision (2% relative error) and relatively short respond time (9.7 to 2.0 seconds at 589 to 728K), the technique was successfully applied to a dynamic study of hydrogenation reactions in this work. Furthermore, the technique is to be tested for industrial uses. Hydrogen/1-methylnaphthalene system was experimentally investigated in a one-liter autoclave equipped with a magnetically driven stirrer and temperature controlling devices. Catalytic hydrogenation of 1-methylnaphthalene was studied in the presence of sulfidedmore » Co-Mo-Al2O3 catalyst. In addition, the vapor/liquid equilibrium relationship was determined by using this technique. Hydrogenation reaction runs were performed at temperatures of 644.1, 658.0 and 672.0K and pressures up to 9.0 MPa. The ring hydrogenation, resulting in 1- and 5-methyltetralin, was found to be the dominant reaction. This is in agreement with cited literature. Effects of hydrogen partial pressure, operating temperature, as well as presulfided catalyst are also investigated and discussed in this work. The vapor pressure of 1-methylnaphthalene was measured over a temperature range of 555.2 to 672.0K. The results are in good agreement with literature data. Measurements for hydrogen solubility in 1-methylnaphthalene were conducted over temperature and pressure range of 598 to 670K and 5.2 to 8.8 MPa, respectively. Similar to previously reported results, the hydrogen solubility increases with increasing temperature when total pressure is held constant. A linear relation is found between the hydrogen solubility and hydrogen partial pressure. 21 refs., 13 figs., 10 tabs.« less

The Relationship of Mucus Concentration (Hydration) to Mucus Osmotic Pressure and Transport in Chronic Bronchitis

PubMed Central

Coakley, Raymond D.; Button, Brian; Henderson, Ashley G.; Zeman, Kirby L.; Alexis, Neil E.; Peden, David B.; Lazarowski, Eduardo R.; Davis, C. William; Bailey, Summer; Fuller, Fred; Almond, Martha; Qaqish, Bahjat; Bordonali, Elena; Rubinstein, Michael; Bennett, William D.; Kesimer, Mehmet; Boucher, Richard C.

2015-01-01

Rationale: Chronic bronchitis (CB) is characterized by persistent cough and sputum production. Studies were performed to test whether mucus hyperconcentration and increased partial osmotic pressure, in part caused by abnormal purine nucleotide regulation of ion transport, contribute to the pathogenesis of CB. Objectives: We tested the hypothesis that CB is characterized by mucus hyperconcentration, increased mucus partial osmotic pressures, and reduced mucus clearance. Methods: We measured in subjects with CB as compared with normal and asymptomatic smoking control subjects indices of mucus concentration (hydration; i.e., percentage solids) and sputum adenine nucleotide/nucleoside concentrations. In addition, sputum partial osmotic pressures and mucus transport rates were measured in subjects with CB. Measurements and Results: CB secretions were hyperconcentrated as indexed by an increase in percentage solids and total mucins, in part reflecting decreased extracellular nucleotide/nucleoside concentrations. CB mucus generated concentration-dependent increases in partial osmotic pressures into ranges predicted to reduce mucus transport. Mucociliary clearance (MCC) in subjects with CB was negatively correlated with mucus concentration (percentage solids). As a test of relationships between mucus concentration and disease, mucus concentrations and MCC were compared with FEV1, and both were significantly correlated. Conclusions: Abnormal regulation of airway surface hydration may slow MCC in CB and contribute to disease pathogenesis. PMID:25909230

Vapor-Phase Stoichiometry and Heat Treatment of CdTe Starting Material for Physical Vapor Transport

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Sha, Yi-Gao; Lehoczky, S. L.; Liu, Hao-Chieh; Fang, Rei; Brebrick, R. F.

1998-01-01

Six batches of CdTe, having total amounts of material from 99 to 203 g and gross mole fraction of Te, X(sub Te), 0.499954-0.500138, were synthesized from pure Cd and Te elements. The vapor-phase stoichiometry of the assynthesized CdTe batches was determined from the partial pressure of Te2, P(sub Te2) using an optical absorption technique. The measured vapor compositions at 870 C were Te-rich for all of the batches with partial pressure ratios of Cd to Te2, P(sub Cd)/P(sub Te2), ranging from 0.00742 to 1.92. After the heat treatment of baking under dynamic vacuum at 870 C for 8 min, the vapor-phase compositions moved toward that of the congruent sublimation, i.e. P(sub Cd)/P(sub Te2) = 2.0, with the measured P(sub Cd)/P(sub Te2) varying from 1.84 to 3.47. The partial pressure measurements on one of the heat-treated samples also showed that the sample remained close to the congruent sublimation condition over the temperature range 800-880 C.

Oxidation of SiC Fiber-Reinforced SiC Matrix Composites with a BN Interphase

NASA Technical Reports Server (NTRS)

Opila, Elizabeth; Boyd, Meredith K.

2010-01-01

SiC-fiber reinforced SiC matrix composites with a BN interphase were oxidized in reduced oxygen partial pressures of oxygen to simulate the environment for hypersonic vehicle leading edge applications. The constituent fibers as well as composite coupons were oxidized in oxygen partial pressures ranging from 1000 ppm O2 to 5% O2 balance argon. Exposure temperatures ranged from 816 C to 1353 C (1500 F to 2450 F). The oxidation kinetics of the coated fibers were monitored by thermogravimetric analysis (TGA). An initial rapid transient weight gain was observed followed by parabolic kinetics. Possible mechanisms for the transient oxidation are discussed. One edge of the composite coupon seal coat was ground off to simulate damage to the composite which allowed oxygen ingress to the interior of the composite. Oxidation kinetics of the coupons were characterized by scanning electron microscopy since the weight changes were minimal. It was found that sealing of the coupon edge by silica formation occurred. Differences in the amount and morphology of the sealing silica as a function of time, temperature and oxygen partial pressure are discussed. Implications for use of these materials for hypersonic vehicle leading edge materials are summarized.

Nonflat equilibrium liquid shapes on flat surfaces.

PubMed

Starov, Victor M

2004-01-15

The hydrostatic pressure in thin liquid layers differs from the pressure in the ambient air. This difference is caused by the actions of surface forces and capillary pressure. The manifestation of the surface force action is the disjoining pressure, which has a very special S-shaped form in the case of partial wetting (aqueous thin films and thin films of aqueous electrolyte and surfactant solutions, both free films and films on solid substrates). In thin flat liquid films the disjoining pressure acts alone and determines their thickness. However, if the film surface is curved then both the disjoining and the capillary pressures act simultaneously. In the case of partial wetting their simultaneous action results in the existence of nonflat equilibrium liquid shapes. It is shown that in the case of S-shaped disjoining pressure isotherm microdrops, microdepressions, and equilibrium periodic films exist on flat solid substrates. Criteria are found for both the existence and the stability of these nonflat equilibrium liquid shapes. It is shown that a transition from thick films to thinner films can go via intermediate nonflat states, microdepressions and periodic films, which both can be more stable than flat films within some range of hydrostatic pressure. Experimental investigations of shapes of the predicted nonflat layers can open new possibilities of determination of disjoining pressure in the range of thickness in which flat films are unstable.

Biological nitrogen fixation under primordial Martian partial pressures of dinitrogen

NASA Technical Reports Server (NTRS)

Klingler, J. M.; Mancinelli, R. L.; White, M. R.

1989-01-01

One of the most striking differences between the conditions on early Mars and earth was a low (18 mb) partial pressure of N2 (pN2) on early Mars, as opposed to 780 mb N2 on earth. To investigate the possibility of biological nitrogen fixation under conditions of early Mars, experiments were carried out on the growth of Azotobacter vinelandii and Azomonas agilis in nitrogen-free synthetic medium under various partial pressures of N2 (ranging from 780 to 0 mb). It was found that, although the biomass, cell number, and growth rate of these bacteria decreased with decreasing pN2 values below pN2 of 400 mb, both microorganisms were capable of growing at pN2 as low as 5 mb (but not at of below 1 mb), indicating that biological fixation of nitrogen could have occurred on primordial Mars.

A defect model for UO2+x based on electrical conductivity and deviation from stoichiometry measurements

NASA Astrophysics Data System (ADS)

Garcia, Philippe; Pizzi, Elisabetta; Dorado, Boris; Andersson, David; Crocombette, Jean-Paul; Martial, Chantal; Baldinozzi, Guido; Siméone, David; Maillard, Serge; Martin, Guillaume

2017-10-01

Electrical conductivity of UO2+x shows a strong dependence upon oxygen partial pressure and temperature which may be interpreted in terms of prevailing point defects. A simulation of this property along with deviation from stoichiometry is carried out based on a model that takes into account the presence of impurities, oxygen interstitials, oxygen vacancies, holes, electrons and clusters of oxygen atoms. The equilibrium constants for each defect reaction are determined to reproduce the experimental data. An estimate of defect concentrations and their dependence upon oxygen partial pressure can then be determined. The simulations carried out for 8 different temperatures (973-1673 K) over a wide range of oxygen partial pressures are discussed and resulting defect equilibrium constants are plotted in an Arrhenius diagram. This provides an estimate of defect formation energies which may further be compared to other experimental data or ab-initio and empirical potential calculations.

Germination and growth of lettuce (Lactuca sativa) at low atmospheric pressure

NASA Technical Reports Server (NTRS)

Spanarkel, Robert; Drew, Malcolm C.

2002-01-01

The response of lettuce (Lactuca sativa L. cv. Waldmann's Green) to low atmospheric pressure was examined during the initial 5 days of germination and emergence, and also during subsequent growth to vegetative maturity at 30 days. Growth took place inside a 66-l-volume low pressure chamber maintained at 70 kPa, and plant response was compared to that of plants in a second, matching chamber that was at ambient pressure (approximately 101 kPa) as a control. In other experiments, to determine short-term effects of low pressure transients, plants were grown at ambient pressure until maturity and then subjected to alternating periods of 24 h of low and ambient atmospheric pressures. In all treatments the partial pressure of O2 was maintained at 21 kPa (approximately the partial pressure in air at normal pressure), and the partial pressure of CO2 was in the range 66.5-73.5 Pa (about twice that in normal air) in both chambers, with the addition of CO2 during the light phase. With continuous exposure to low pressure, shoot and root growth was at least as rapid as at ambient pressure, with an overall trend towards slightly greater performance at the lower pressure. Dark respiration rates were greater at low pressure. Transient periods at low pressure decreased transpiration and increased dark respiration but only during the period of exposure to low pressure. We conclude that long-term or short-term exposure to subambient pressure (70 kPa) was without detectable detriment to vegetative growth and development.

Effects of Environmental Oxygen Content and Dissolved Oxygen on the Surface Tension and Viscosity of Liquid Nickel

NASA Astrophysics Data System (ADS)

SanSoucie, M. P.; Rogers, J. R.; Kumar, V.; Rodriguez, J.; Xiao, X.; Matson, D. M.

2016-07-01

The NASA Marshall Space Flight Center's electrostatic levitation (ESL) laboratory has recently added an oxygen partial pressure controller. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled in the range from approximately 10^{-28} {to} 10^{-9} bar, while in a vacuum atmosphere. The oxygen control system installed in the ESL laboratory's main chamber consists of an oxygen sensor, oxygen pump, and a control unit. The sensor is a potentiometric device that determines the difference in oxygen activity in two gas compartments (inside the chamber and the air outside of the chamber) separated by an electrolyte. The pump utilizes coulometric titration to either add or remove oxygen. The system is controlled by a desktop control unit, which can also be accessed via a computer. The controller performs temperature control for the sensor and pump, has a PID-based current loop and a control algorithm. Oxygen partial pressure has been shown to play a significant role in the surface tension of liquid metals. Oxide films or dissolved oxygen may lead to significant changes in surface tension. The effects on surface tension and viscosity by oxygen partial pressure in the surrounding environment and the melt dissolved oxygen content will be evaluated, and the results will be presented. The surface tension and viscosity will be measured at several different oxygen partial pressures while the sample is undercooled. Surface tension and viscosity will be measured using the oscillating droplet method.

CO.sub.2 Pretreatment prevents calcium carbonate formation

DOEpatents

Neavel, Richard C.; Brunson, Roy J.; Chaback, Joseph J.

1980-01-01

Scale formation during the liquefaction of lower ranking coals and similar carbonaceous materials is significantly reduced and/or prevented by pretreatment with carbon dioxide. The carbon dioxide pretreatment is believed to convert the scale-forming components to the corresponding carbonate prior to liquefaction. The pretreatment is accomplished at a total pressure within the range from about 14 to about 68 atmospheres and a carbon dioxide partial pressure within the range from about 14 to about 34 atmospheres. Temperature during pretreatment will generally be within the range from about 100.degree. to about 200.degree. C.

Flow-independent dynamics in aneurysm (FIDA): pressure measurements following partial and complete flow impairment in experimental aneurysm model

PubMed Central

Watanabe, Masaki; Chaudhry, Saqib A; Qureshi, Adnan I

2014-01-01

Background: There have been growing concerns regarding delayed aneurysm rupture subsequent to the flow-diverting stent deployment. Therefore, more investigations are needed regarding hemodynamic changes secondary to flow-diverting stent deployment. Objective: To study intra-aneurysmal and perianeurysmal pressures after partial and complete flow impairment into the aneurysm. Methods A silicone model of an 8-mm-sized aneurysm (neck diameter: 5 mm, vessel size: 4 mm) was used. The aneurysm wall was encapsulated and sealed within a 5 ml syringe filled with saline and a pressure sensor guide wire (ComboWire, Volcano Corp.) to detect pressure changes in the perivascular compartment (outer aneurysm wall). A second pressure sensor guide wire was advanced inside the aneurysm sac. Both pressure sensors were continuously measuring pressure inside and outside the aneurysm under pulsatile flow under the following conditions: 1) baseline (reference); 2) a 16 mm by 3.75 mm flow-diverting stent (ev3/Covidien Vascular, Mansfield, MA) deployed in front of the aneurysm; 3) two flow-diverting stents (16 mm by 3.5 mm) were deployed; and 4) a covered stent (4 mm by 16 mm VeriFlex coronary artery stent covered with rubber sheet) was deployed. Results: Mean (±SD) baseline pressures inside and outside the aneurysm were 53.9 (±2.4) mmHg (range 120–40 mmHg) and 15.4 (±0.7) mmHg (range 40–8mmHg), respectively. There was no change in pressure inside and outside the aneurysm after deploying the first and second flow-diverting stents (partial flow impairment) and it remained at 53.9 (±2.7) mmHg and 14.9 (±1) mmHg for the pressure inside and outside the aneurysm, respectively. The pressure recording from outside the aneurysm dropped from 15.4 (±0.7) mmHg to 0.3 (±0.7) mmHg after deploying the covered stent (complete flow impairment). There was no change in pressure inside the aneurysm after deploying the covered stent. Mean (±SD) pressure within the aneurysm was 55.1 (±1.7) mmHg and it remained 54.7 (±1.7) mmHg after covered stent deployment. Conclusion: Our findings suggest a major discordance between the pressures within the aneurysm and partial or complete flow impairment (flow independent). The outer wall pressure is reduced after covered stent placement. These finding may assist clinicians in better understanding of aneurysm hemodynamics and rupture after flow-diverting stent deployment. PMID:25298859

Partial melting of metagreywackes, Part II. Compositions of minerals and melts

NASA Astrophysics Data System (ADS)

Montel, Jean-Marc; Vielzeuf, Daniel

A series of experiments on the fluid-absent melting of a quartz-rich aluminous metagreywacke has been carried out. In this paper, we report the chemical composition of the phases present in the experimental charges as determined by electron microprobe. This analytical work includes biotite, plagioclase, orthopyroxene, garnet, cordierite, hercynite, staurolite, gedrite, oxide, and glass, over the range 100-1000MPa, 780-1025°C. Biotites are Na- and Mg-rich, with Ti contents increasing with temperature. The compositions of plagioclase range from An17 to An35, with a significant orthoclase component, and are always different from the starting minerals. At high temperature, plagioclase crystals correspond to ternary feldspars with Or contents in the range 11-20 mol%. Garnets are almandine pyrope grossular spessartine solid solutions, with a regular and significant increase of the grossular content with pressure. All glasses are silicic (SiO2=67.6-74.4 wt%), peraluminous, and leucocratic (FeO+MgO=0.9-2.9 wt%), with a bulk composition close to that of peraluminous leucogranites, even for degrees of melting as high as 60 vol.%. With increasing pressure, SiO2 contents decrease while K2O increases. At any pressure, the melt compositions are more potassic than the water-saturated granitic minima. The H2O contents estimated by mass balance are in the range 2.5-5.6 wt%. These values are higher than those predicted by thermodynamic models. Modal compositions were estimated by mass balance calculations and by image processing of the SEM photographs. The positions of the 20 to 70% isotects (curves of equal proportion of melt) have been located in the pressure-temperature space between 100MPa and 1000MPa. With increasing pressure, the isotects shift toward lower temperature between 100 and 200MPa, then bend back toward higher temperature. The melting interval increases with pressure; the difference in temperature between the 20% and the 70% isotects is 40°C at 100MPa, and 150°C at 800MPa. The position of the isotects is interpreted in terms of both the solubility of water in the melt and the nature of the reactions involved in the melting process. A comparison with other partial melting experiments suggests that pelites are the most fertile source rocks above 800MPa. The difference in fertility between pelites and greywackes decreases with decreasing pressure. A review of the glass compositions obtained in experimental studies demonstrates that partial melting of fertile rock types in the crust (greywackes, pelites, or orthogneisses) produces only peraluminous leucogranites. More mafic granitic compositions such as the various types of calk-alkaline rocks, or mafic S-type rocks, have never been obtained during partial melting experiments. Thus, only peraluminous leucogranites may correspond to liquids directly formed by partial melting of metasediments. Other types of granites involve other components or processes, such as restite unmixing from the source region, and/or interaction with mafic mantle-derived materials.

Effect of water on the composition of partial melts of greenstone and amphibolite

NASA Technical Reports Server (NTRS)

Beard, James S.; Lofgren, Gary E.

1989-01-01

Closed-system partial melts of hydrated, metamorphosed arc basalts and andesites (greenstones and amphibolites), where only water structurally bound in metamorphic minerals is available for melting (dehydration melting), are generally water-undersaturated, coexist with plagioclase-rich, anhydrous restites, and have compositions like island arc tonalites. In contrast, water-saturated melting at water pressures of 3 kilobars yields strongly peraluminous, low iron melts that coexist with an amphibole-bearing, plagioclase-poor restite. These melt compositions are unlike those of most natural silicic rocks. Thus, dehydration melting over a range of pressures in the crust of island arcs is a plausible mechanism for the petrogenesis of islands arc tonalite, whereas water-saturated melting at pressure of 3 kilobars and above is not.

Carbon acceptor incorporation in GaAs grown by metalorganic chemical vapor deposition: Arsine versus tertiarybutylarsine

NASA Astrophysics Data System (ADS)

Watkins, S. P.; Haacke, G.

1991-10-01

Undoped p-type GaAs epilayers were grown by low-pressure metalorganic chemical vapor deposition (MOCVD) at 650 °C and 76 Torr using either arsine or tertiarybutylarsine (TBA), and trimethylgallium (TMG). Extremely high-purity precursors were used in order to eliminate extrinsic doping effects. Carbon acceptors from the TMG were the dominant residual electrical impurities under all growth conditions. Temperature-dependent Hall measurements were used to make a quantitative comparison of the carbon acceptor concentrations for arsine- and TBA-grown epilayers over a range of As partial pressures. For a given group V partial pressure, we report a significant reduction in carbon acceptor incorporation using TBA compared with arsine under identical growth conditions.

Rapid Liver Hypertrophy After Portal Vein Occlusion Correlates with the Degree of Collateralization Between Lobes-a Study in Pigs.

PubMed

Deal, Rebecca; Frederiks, Charles; Williams, Lauren; Olthof, Pim B; Dirscherl, Konstantin; Keutgen, Xavier; Chan, Edie; Deziel, Daniel; Hertl, Martin; Schadde, Erik

2018-02-01

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) induces more rapid liver growth than portal vein ligation (PVL). Transection of parenchyma in ALPPS may prevent the formation of collaterals between lobes. The aim of this study was to determine if abrogating the formation of collaterals through parenchymal transection impacted growth rate. Twelve Yorkshire Landrace pigs were randomized to undergo ALPPS, PVL, or "partial ALPPS" by varying degrees of parenchymal transection. Hepatic volume was measured after 7 days. Portal blood flow and pressure were measured. Portal vein collaterals were examined from epoxy casts. PVL, ALPPS, and partial ALPPS led to volume increases of the RLL by 15.5% (range 3-22), 64% (range 45-76), and 32% (range 18-77), respectively, with significant differences between PVL and ALPPS/partial ALPPS (p < 0.05). In PVL and partial ALPPS, substantial new portal vein collaterals were found. The number of collaterals correlated inversely with the growth rate (p = 0.039). Portal vein pressure was elevated in all models after ligation suggesting hyperflow to the portal vein-supplied lobe (p < 0.05). These data suggest that liver hypertrophy following PVL is inversely proportional to the development of collaterals. Hypertrophy after ALPPS is likely more rapid due to reduction of collaterals through transection.

Some flow phenomena in a constant area duct with a Borda type inlet including the critical region

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Simoneau, R. J.

1978-01-01

Mass limiting flow characteristics for a 55 L/D tube with a Borda type inlet were assessed over large ranges of temperature and pressure, using fluid nitrogen. Under certain conditions, separation and pressure drop at the inlet was sufficiently strong to permit partial vaporization and the remaining fluid flowed through the tube as if it were a free jet. An empirical relation was determined which defines conditions under which this type of flow can occur. A flow coefficient is presented which enables estimations of flow rates over the experimental range. A flow rate stagnation pressure map for selected stagnation isotherms and pressure profiles document these flow phenomena.

Formulation of steam-methane reforming rate in Ni-YSZ porous anode of solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Sugihara, Shinichi; Kawamura, Yusuke; Iwai, Hiroshi

2018-02-01

The steam-methane reforming reaction on a Ni-YSZ (yttria-stabilized zirconia) cermet was experimentally investigated under atmospheric pressure and in the temperature range from 650 to 750 °C. We examined the effects of the partial pressures of methane and steam in the supply gas on the reaction rate. The experiments were conducted with a low Ni contained Ni-YSZ cermet sheet of thickness 0.1 mm. Its porous microstructure and accompanied parameters were quantified using the FIB-SEM (focused ion beam scanning electron microscopy) technique. A power-law-type rate equation incorporating the reaction-rate-limiting conditions was obtained on the basis of the unit surface area of the Ni-pore contact surface in the cermet. The kinetics indicated a strong positive dependence on the methane partial pressure and a negative dependence on the steam partial pressure. The obtained rate equation successfully reproduced the experimental results for Ni-YSZ samples having different microstructures in the case of low methane consumption. The equation also reproduced the limiting-reaction behaviours at different temperatures.

Novel application of lower body positive-pressure in the rehabilitation of an individual with multiple lower extremity fractures.

PubMed

Takacs, Judit; Leiter, Jeff R S; Peeler, Jason D

2011-06-01

Lower extremity fractures, if not treated appropriately, can increase the risk of morbidity. Partial weight-bearing after surgical repair is recommended; however, current methods of partial weight-bearing may cause excessive loads through the lower extremity. A new rehabilitation tool that uses lower body positive-pressure is described, that may allow partial weight-bearing while preventing excessive loads, thereby improving functional outcomes. A patient with multiple lower extremity fractures underwent a 6-month rehabilitation programme using bodyweight support technology 3 times per week, post-surgery. The patient experienced a reduction in pain and an improvement in ankle range of motion (p=0.002), walking speed (p>0.05) and physical function (p=0.004), as assessed by the Foot and Ankle Module of the American Academy of Orthopaedic Surgeons Lower Limb Outcomes Assessment Instrument. Training did not appear to affect fracture healing, as was evident on radiograph. The effect of lower body positive-pressure on effusion, which has not previously been reported in the literature, was also investigated. No significant difference in effusion of the foot and ankle when using lower body positive-pressure was found. Initial results suggest that this new technology may be a useful rehabilitation tool that allows partial weight-bearing during the treatment of lower extremity injuries.

Measurement and Control of Oxygen Partial Pressure in an Electrostatic Levitator

NASA Technical Reports Server (NTRS)

SanSoucie, Michael P.; Rogers, Jan R.

2014-01-01

Recently the NASA Marshall Space Flight Center electrostatic levitation (ESL) laboratory has been upgraded to include an oxygen control system. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled, at elevated temperatures, theoretically in the range from 10(exp -36) to 10(exp 0) bar. The role of active surface agents in liquid metals is fairly well known; however, published surface tension data typically has large scatter, which has been hypothesized to be caused by the presence of oxygen. The surface tension of metals is affected by even a small amount of adsorption of oxygen. It has even been shown that oxygen partial pressures may need to be as low as 10(exp -24) bar to avoid oxidation. While electrostatic levitation is done under high vacuum, oxide films or dissolved oxygen may have significant effects on materials properties, such as surface tension and viscosity. Therefore, the ability to measure and control the oxygen partial pressure within the chamber is highly desirable. The oxygen control system installed at MSFC contains a potentiometric sensor, which measures the oxygen partial pressure, and an oxygen ion pump. In the pump, a pulse-width modulated electric current is applied to yttrium-stabilized zirconia, resulting in oxygen transfer into or out of the system. Also part of the system is a control unit, which consists of temperature controllers for the sensor and pump, PID-based current loop for the ion pump, and a control algorithm. This system can be used to study the effects of oxygen on the thermophysical properties of metals, ceramics, glasses, and alloys. It can also be used to provide more accurate measurements by processing the samples at very low oxygen partial pressures. The oxygen control system will be explained in more detail and an overview of its use and limitations in an electrostatic levitator will be described. Some preliminary measurements have been made, and the results to date will be provided.

Electrical conductivity of cobalt doped La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ

NASA Astrophysics Data System (ADS)

Wang, Shizhong; Wu, Lingli; Liang, Ying

La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ (LSGM8282), La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ (LSGMC5) and La 0.8Sr 0.2Ga 0.8Mg 0.115Co 0.085O 3- δ (LSGMC8.5) were prepared using a conventional solid-state reaction. Electrical conductivities and electronic conductivities of the samples were measured using four-probe impedance spectrometry, four-probe dc polarization and Hebb-Wagner polarization within the temperature range of 973-1173 K. The electrical conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high (>10 -5 atm) and low oxygen partial pressure regions (<10 -15 atm). However, the electrical conductivity in LSGM8282 had no dependency on the oxygen partial pressure. At temperatures higher than 1073 K, PO2 dependencies of the free electron conductivities in LSGM8282, LSGMC5 and LSGMC8.5 were about -1/4, and PO2 dependencies of the electron hole conductivities were about 0.25, 0.12 and 0.07, respectively. Oxygen ion conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high and low oxygen partial pressure regions, which was due to the increase in the concentration of oxygen vacancies. The change in the concentration of oxygen vacancies and the valence of cobalt with oxygen partial pressure were determined using a thermo-gravimetric technique. Both the electronic conductivity and oxygen ion conductivity in cobalt doped lanthanum gallate samples increased with increasing concentration of cobalt, suggesting that the concentration of cobalt should be optimized carefully to maintain a high electrical conductivity and close to 1 oxygen ion transference number.

Chemical reactions and morphological stability at the Cu/Al2O3 interface.

PubMed

Scheu, C; Klein, S; Tomsia, A P; Rühle, M

2002-10-01

The microstructures of diffusion-bonded Cu/(0001)Al2O3 bicrystals annealed at 1000 degrees C at oxygen partial pressures of 0.02 or 32 Pa have been studied with various microscopy techniques ranging from optical microscopy to high-resolution transmission electron microscopy. The studies revealed that for both oxygen partial pressures a 20-35 nm thick interfacial CuAlO2 layer formed, which crystallises in the rhombohedral structure. However, the CuAlO2 layer is not continuous, but interrupted by many pores. In the samples annealed in the higher oxygen partial pressure an additional reaction phase with a needle-like structure was observed. The needles are several millimetres long, approximately 10 microm wide and approximately 1 microm thick. They consist of CuAlO2 with alternating rhombohedral and hexagonal structures. Solid-state contact angle measurements were performed to derive values for the work of adhesion. The results show that the adhesion is twice as good for the annealed specimen compared to the as-bonded sample.

CTR Fuel recovery system using regeneration of a molecular sieve drying bed

DOEpatents

Folkers, Charles L.

1981-01-01

A primary molecular sieve drying bed is regenerated by circulating a hot inert gas through the heated primary bed to desorb water held on the bed. The inert gas plus water vapor is then cooled and passed through an auxiliary molecular sieve bed which adsorbs the water originally desorbed from the primary bed. The main advantage of the regeneration technique is that the partial pressure of water can be reduced to the 10.sup.-9 atm. range. This is significant in certain CTR applications where tritiated water (T.sub.2 O, HTO) must be collected and kept at very low partial pressure.

Low Pressure Flame Blowoff from the Forward Stagnation Region of a Blunt-Nosed Cast PMMA Cylinder in Axial Mixed Convective Flow

NASA Technical Reports Server (NTRS)

Marcum, J. W.; Rachow, P.; Ferkul, P. V.; Olson, S. L.

2017-01-01

Low-pressure blowoff experiments were conducted with a stagnation flame stabilized on the forward tip of cast PMMA rods in a vertical wind tunnel. Pressure, forced flow velocity, gravity, and ambient oxygen concentration were varied. Stagnation flame blowoff is determined from a time-stamped video recording of the test. The blowoff pressure is determined from test section pressure transducer data that is synchronized with the time stamp. The forced flow velocity is also determined from the choked flow orifice pressure. Most of the tests were performed in normal gravity, but a handful of microgravity tests were also conducted to determine the influence of buoyant flow velocity on the blowoff limits. The blowoff limits are found to have a linear dependence between the partial pressure of oxygen and the total pressure, regardless of forced flow velocity and gravity level. The flow velocity (forced and/or buoyant) affects the blowoff pressure through the critical Damkohler number residence time, which dictates the partial pressure of oxygen at blowoff. This is because the critical stretch rate increases linearly with increasing pressure at low pressure (sub-atmospheric pressures) since a second-order overall reaction rate with two-body reactions dominates in this pressure range.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Groenen, Rik; Smit, Jasper; Orsel, Kasper

The oxidation of species in the plasma plume during pulsed laser deposition controls both the stoichiometry as well as the growth kinetics of the deposited SrTiO{sub 3} thin films, instead of the commonly assumed mass distribution in the plasma plume and the kinetic energy of the arriving species. It was observed by X-ray diffraction that SrTiO{sub 3} stoichiometry depends on the composition of the background gas during deposition, where in a relative small pressure range between 10{sup −2} mbars and 10{sup −1} mbars oxygen partial pressure, the resulting film becomes fully stoichiometric. Furthermore, upon increasing the oxygen (partial) pressure, themore » growth mode changes from 3D island growth to a 2D layer-by-layer growth mode as observed by reflection high energy electron diffraction.« less

High pressure effects on U L 3 x-ray absorption in partial fluorescence yield mode and single crystal x-ray diffraction in the heavy fermion compound UCd 11

DOE PAGES

Nasreen, Farzana; Antonio, Daniel; VanGennep, Derrick; ...

2016-02-15

© 2016 IOP Publishing Ltd. We report a study of high pressure x-ray absorption (XAS) performed in the partial fluorescence yield mode (PFY) at the U L 3 edge (0-28.2 GPa) and single crystal x-ray diffraction (SXD) (0-20 GPa) on the UCd 11 heavy fermion compound at room temperature. Under compression, the PFY-XAS results show that the white line is shifted by +4.1(3) eV at the highest applied pressure of 28.2 GPa indicating delocalization of the 5f electrons. The increase in full width at half maxima and decrease in relative amplitude of the white line with respect to the edgemore » jump point towards 6d band broadening under high pressure. A bulk modulus of K 0 = 62(1) GPa and its pressure derivative, = 4.9(2) was determined from high pressure SXD results. Both the PFY-XAS and diffraction results do not show any sign of a structural phase transition in the applied pressure range.« less

Gas-liquid equilibrium in a CO{sub 2}-MDEA-H{sub 2}O system and the effect of piperazine on it

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, G.W.; Zhang, C.F.; Qin, S.J.

1998-04-01

Aqueous N-methyldiethanolamine (MDEA) solutions are widely used for removal of the acid gas (H{sub 2}S and CO{sub 2}) from natural gas synthesis and refinery gas streams. Solubility data of CO{sub 2} and vapor pressure of water in 3.04--4.28 kmol/m{sup 3} aqueous N-methyldiethanolamine (MDEA) solutions were obtained at temperatures ranging from 40 to 100 C and CO{sub 2} partial pressures ranging from 0.876 to 1,013 kPa. A thermodynamic model was proposed and used for predicting CO{sub 2} solubility and water vapor pressure. An enthalpy change of absorption of CO{sub 2} in 4.28 kmol/m{sup 3} MDEA solution was estimated. The effect ofmore » piperazine (PZ) concentration on CO{sub 2} loading in MDEA solutions was determined at piperazine concentration ranging from 0 to 0.515 kmol/m{sup 3}. The results show that piperazine is beneficial to the CO{sub 2} loading. The equilibrium partial pressure of piperazine in the PZ-MDEA-H{sub 2}O system was measured in an Ellis Cell. Results show that the PZ-MDEA-H{sub 2}O system is a typical negative deviation system, with the strength of deviation decreasing with MDEA solutions.« less

Direct computation of thermodynamic properties of chemically reacting air with consideration to CFD

NASA Astrophysics Data System (ADS)

Iannelli, Joe

2003-10-01

This paper details a two-equation procedure to calculate exactly mass and mole fractions, pressure, temperature, specific heats, speed of sound and the thermodynamic and jacobian partial derivatives of pressure and temperature for a five-species chemically reacting equilibrium air. The procedure generates these thermodynamic properties using as independent variables either pressure and temperature or density and internal energy, for CFD applications. An original element in this procedure consists in the exact physically meaningful solution of the mass-fraction and mass-action equations. Air-equivalent molecular masses for oxygen and nitrogen are then developed to account, within a mixture of only oxygen and nitrogen, for the presence of carbon dioxide, argon and the other noble gases within atmospheric air. The mathematical formulation also introduces a versatile system non-dimensionalization that makes the procedure uniformly applicable to flows ranging from shock-tube flows with zero initial velocity to aerothermodynamic flows with supersonic/hypersonic free-stream Mach numbers. Over a temperature range of more than 10000 K and pressure and density ranges corresponding to an increase in altitude in standard atmosphere of 30000 m above sea level, the predicted distributions of mole fractions, constant-volume specific heat, and speed of sound for the model five species agree with independently published results, and all the calculated thermodynamic properties, including their partial derivatives, remain continuous, smooth, and physically meaningful.

Oxygen Exposure Resulting in Arterial Oxygen Tensions Above the Protocol Goal Was Associated With Worse Clinical Outcomes in Acute Respiratory Distress Syndrome.

PubMed

Aggarwal, Neil R; Brower, Roy G; Hager, David N; Thompson, B Taylor; Netzer, Giora; Shanholtz, Carl; Lagakos, Adrian; Checkley, William

2018-04-01

High fractions of inspired oxygen may augment lung damage to exacerbate lung injury in patients with acute respiratory distress syndrome. Participants enrolled in Acute Respiratory Distress Syndrome Network trials had a goal partial pressure of oxygen in arterial blood range of 55-80 mm Hg, yet the effect of oxygen exposure above this arterial oxygen tension range on clinical outcomes is unknown. We sought to determine if oxygen exposure that resulted in a partial pressure of oxygen in arterial blood above goal (> 80 mm Hg) was associated with worse outcomes in patients with acute respiratory distress syndrome. Longitudinal analysis of data collected in these trials. Ten clinical trials conducted at Acute Respiratory Distress Syndrome Network hospitals between 1996 and 2013. Critically ill patients with acute respiratory distress syndrome. None. We defined above goal oxygen exposure as the difference between the fraction of inspired oxygen and 0.5 whenever the fraction of inspired oxygen was above 0.5 and when the partial pressure of oxygen in arterial blood was above 80 mm Hg. We then summed above goal oxygen exposures in the first five days to calculate a cumulative above goal oxygen exposure. We determined the effect of a cumulative 5-day above goal oxygen exposure on mortality prior to discharge home at 90 days. Among 2,994 participants (mean age, 51.3 yr; 54% male) with a study-entry partial pressure of oxygen in arterial blood/fraction of inspired oxygen that met acute respiratory distress syndrome criteria, average cumulative above goal oxygen exposure was 0.24 fraction of inspired oxygen-days (interquartile range, 0-0.38). Participants with above goal oxygen exposure were more likely to die (adjusted interquartile range odds ratio, 1.20; 95% CI, 1.11-1.31) and have lower ventilator-free days (adjusted interquartile range mean difference of -0.83; 95% CI, -1.18 to -0.48) and lower hospital-free days (adjusted interquartile range mean difference of -1.38; 95% CI, -2.09 to -0.68). We observed a dose-response relationship between the cumulative above goal oxygen exposure and worsened clinical outcomes for participants with mild, moderate, or severe acute respiratory distress syndrome, suggesting that the observed relationship is not primarily influenced by severity of illness. Oxygen exposure resulting in arterial oxygen tensions above the protocol goal occurred frequently and was associated with worse clinical outcomes at all levels of acute respiratory distress syndrome severity.

Thermodynamic Equilibrium Solubility of Diethanolamine – N-Butyl-1-Methylpyrrolidinium Dicyanamide [DEABMPYRR DCA] Mixtures for Carbon Dioxide Capture

NASA Astrophysics Data System (ADS)

Salleh, R. M.; Jamaludin, S. N.

2018-05-01

Solubility data of carbon dioxide (CO2) in aqueous Diethanolamine (DEA) blended with pyrrolidinium-based ionic liquid: N-Butyl-1-Methylpyrrolidinium Dıcyanamıde [Bmpyrr][DCA] are presented at various temperatures (313.15K-333.15K) and pressure up to about 700 psi. The concentration of [Bmpyrr][DCA] ranges from 0-10wt% and 30-40wt% for DEA. The solubility of CO2 was evaluated by measuring the pressure drop in high pressure stirred absorption cell reactor. The CO2 loading in all studied mixtures increases with an increase in CO2 partial pressure and decreases with temperature. It was also found that the CO2 loading capacity decrease as the concentration of [Bmpyrr][DCA] increases. The experimental data were correlated as a function of temperature and CO2 partial pressure to predict the solubility of CO2 in the mixtures. It was found that the model predicted results in a good agreement with experimental value.

Oxygen stoichiometry, phase stability, and thermodynamic behavior of the lead-doped and lead-free Bi-2212 systems

NASA Astrophysics Data System (ADS)

Tetenbaum, M.; Hash, M.; Tani, B. S.; Maroni, V. A.

1996-02-01

Electromotive-force (EMF) measurements of oxygen fugacities as a function of stoichiometry have been made on lead-doped and lead-free Bi 2- zPb zSr 2Ca 1Cu 2O x superconducting ceramics in the temperature range ≈ 700-815°C by means of an oxygen-titration techique that employs an yttria-stabilized zirconia electrolyte. Equations for the variation of oxygen partial pressure with composition and temperature have been derived from our EMF measurements. Thermodynamic assessments of the partial molar quantities Δ overlineH(O 2) and Δ overlineS(O 2) for lead-doped Bi-2212 and lead-free Bi-2212 indicate that the solid-state decomposition of these bismuth cuprates at low oxygen partial pressure can be represented by the diphasic CuOCu 2O system.

Some aspects of the thermodynamic behaviour of the lead-doped Bi-2223 system

NASA Astrophysics Data System (ADS)

Tetenbaum, M.; Maroni, V. A.

1996-02-01

A thermodynamic assessment of lead-doped Bi-2223 with emphasis on compositions and oxygen partial pressures within the homogeneity region prior to solid-state decomposition is presented. Equations for the variation of oxygen partial pressure with composition and temperature have been derived from our EMF measurements. Long-term metastability was indicated during cycling over a temperature range of ∼ 700-815°C of a lead-doped Bi-2223 sample having an oxygen-deficient stoichiometry of 9.64 prior to solid-state decomposition corresponding to the diphasic CuOCu 2O system. A trend of increasing negative values of the partial molar enthalpy Δ overlineH( O 2) and entropy Δ overlineS( O2 with increasing oxygen deficiency of the condensed phase indicated an increase in ordering of the cuprate structure prior to solid-state decomposition.

Spectral properties of gaseous uranium hexafluoride at high temperature

NASA Technical Reports Server (NTRS)

Krascella, N. L.

1980-01-01

A study to determine relative spectral emission and spectral absorption data for UF6-argon mixtures at elevated temperatures is discussed. These spectral data are required to assist in the theoretical analysis of radiation transport in the nuclear fuel-buffer gas region of a plasma core reactor. Relative emission measurements were made for UF6-argon mixtures over a range of temperatures from 650 to 1900 K and in the wavelength range from 600 to 5000 nanometers. All emission results were determined for a total pressure of 1.0 atm. Uranium hexafluoride partial pressures varied from about 3.5 to 12.7 mm Hg. Absorption measurements were attempted at 600, 625, 650 and 675 nanometers for a temperature of 1000 K. The uranium partial pressure for these determinations was 25 mm Hg. The results exhibit appreciable emission for hot UF6-argon mixtures at wavelengths between 600 and 1800 nanometers and no measurable absorption. The equipment used to evaluate the spectral properties of the UF6-argon mixtures included a plasma torch-optical plenum assembly, the monochromator, and the UF6 transfer system. Each is described.

Competitive sorption of carbonate and arsenic to hematite: combined ATR-FTIR and batch experiments.

PubMed

Brechbühl, Yves; Christl, Iso; Elzinga, Evert J; Kretzschmar, Ruben

2012-07-01

The competitive sorption of carbonate and arsenic to hematite was investigated in closed-system batch experiments. The experimental conditions covered a pH range of 3-7, arsenate concentrations of 3-300 μM, and arsenite concentrations of 3-200 μM. Dissolved carbonate concentrations were varied by fixing the CO(2) partial pressure at 0.39 (atmospheric), 10, or 100 hPa. Sorption data were modeled with a one-site three plane model considering carbonate and arsenate surface complexes derived from ATR-FTIR spectroscopy analyses. Macroscopic sorption data revealed that in the pH range 3-7, carbonate was a weak competitor for both arsenite and arsenate. The competitive effect of carbonate increased with increasing CO(2) partial pressure and decreasing arsenic concentrations. For arsenate, sorption was reduced by carbonate only at slightly acidic to neutral pH values, whereas arsenite sorption was decreased across the entire pH range. ATR-FTIR spectra indicated the predominant formation of bidentate binuclear inner-sphere surface complexes for both sorbed arsenate and sorbed carbonate. Surface complexation modeling based on the dominant arsenate and carbonate surface complexes indicated by ATR-FTIR and assuming inner-sphere complexation of arsenite successfully described the macroscopic sorption data. Our results imply that in natural arsenic-contaminated systems where iron oxide minerals are important sorbents, dissolved carbonate may increase aqueous arsenite concentrations, but will affect dissolved arsenate concentrations only at neutral to alkaline pH and at very high CO(2) partial pressures. Copyright © 2012 Elsevier Inc. All rights reserved.

REVIEW: High pressure NMR study of proteins - seeking roots for function, evolution, disease and food applications

NASA Astrophysics Data System (ADS)

Akasaka, Kazuyuki

2010-12-01

NMR experiments at variable pressure reveal a wide range of conformation of a globular protein spanning from within the folded ensemble to the fully unfolded ensemble, herewith collectively called "high-energy conformers". The observation of "high-energy conformers" in a wide variety of globular proteins has led to the "volume theorem": the partial molar volume of a protein decreases with the decrease in its conformational order. Since "high-energy conformers" are intrinsically more reactive than the basic folded conformer, they could play decisive roles in all phenomena of proteins, namely function, environmental adaptation and misfolding. Based on the information on high-energy conformers and the rules on their partial volume in its monomeric state and amyloidosis, one may have a general view on what is happening on proteins under pressure. Moreover, one may even choose a high-energy conformer of a protein with pressure as variable for a particular purpose. Bridging "high-energy conformers" to macroscopic pressure effects could be a key to success in pressure application to biology, medicine, food technology and industry in the near future.

Experimental validation of Critical Temperature-Pressure theory of scuffing

NASA Astrophysics Data System (ADS)

Lee, Si C.; Chen, Huanliang

1995-07-01

A series of experiments was conducted for validating a newly developed theory of scuffing. The Critical temperature-Pressure (CTP) theory is based on the physisorption behavior of lubricants and is capable of predicting the onset of scuffing failures over a wide range of operating conditions, including the contacts operating in the boundary lubrication and in the partial elastohydrodynamic lubrication (EHL) regimes. According to the CTP theory, failures occur when the contact temperature exceeds a certain critical value which is a function of the lubricant pressure generated by the hydrodynamic action of the EHL contact. A special device capable of simulating the ambient conditions of the partial EHL conjunctions (of contact temperature, pressure, and the lubricant pressure) was constructed. A ball-on-flat type wear tester was put inside a pressure vessel, completely immersed in a highly pressurized bath of mineral oil. The temperature on the flat specimen was gradually increased while the ball was slowly traversed. At a certain critical temmperature, the friction force abruptly jumped indicating the incipiency of the lubrication breakdown. This experiment was repeated for several levels of hydrostatic pressure and the corresponding critical temperatures were obtained. The test results showed an excellent correlation with the newly developed CTP theory.

Thin film devices used as oxygen partial pressure sensors

NASA Technical Reports Server (NTRS)

Canady, K. S.; Wortman, J. J.

1970-01-01

Electrical conductivity of zinc oxide films to be used in an oxygen partial pressure sensor is measured as a function of temperature, oxygen partial pressure, and other atmospheric constituents. Time response following partial pressure changes is studied as a function of temperature and environmental changes.

Plasma polymerization of ethylene in an atmospheric pressure-pulsed discharge

NASA Technical Reports Server (NTRS)

Donohoe, K.; Wydeven, T.

1979-01-01

The polymerization of ethylene in an atmospheric pressure-pulsed discharge has been studied. Partial pressures of ethylene up to 4 kN/sq m were used with helium as a diluent. Deposition rates (on glass slides) were the same throughout the discharge volume over a wide range of operating conditions. These rates were in the 1-2 A/sec range. The films were clear, soft, and showed good adhesion to the glass substrates. Oligomers large enough to visibly scatter 637.8-nm light were observed in the gas phase under all conditions in which film deposition occurred. The experimental results suggest that Brownian diffusion of these oligomers was the rate-limiting step in the film deposition process.

Investigation of uranium plasma emission from 1050 to 6000 A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mack, J.M. Jr.

1977-12-01

Absolute emission coefficient measurements on arc-generated uranium plasmas in local thermodynamic equilibrium are described for a wavelength bandwidth of 1050 to 6000A. Low- and high-pressure arcs were investigated for their emission properties, characteristic temperatures and uranium partial pressures. Temperatures from 5500 to 8000 K and uranium partial pressures from 0.001 to 0.01 atm were found at the arc centerline. The new emission data are compared with other similar experimental results and to existing theoretical calculations. The effects of cold-layer UF/sub 6/ photoabsorption on uranium plasma emission characteristics are established for UF/sub 6/ molecular densities ranging from 1.0 x 10/sup 16/more » to 1.0 x 10/sup 17/ cm/sup -3/ and layer thickness from 1.0 to 5.0 cm.« less

Correction to the gas phase pressure term in the continuum model for partially saturated granular media presented by Pietruszczak and co-workers

NASA Astrophysics Data System (ADS)

Iveson, Simon M.

2003-06-01

Pietruszczak and coworkers (Internat. J. Numer. Anal. Methods Geomech. 1994; 18(2):93-105; Comput. Geotech. 1991; 12( ):55-71) have presented a continuum-based model for predicting the dynamic mechanical response of partially saturated granular media with viscous interstitial liquids. In their model they assume that the gas phase is distributed uniformly throughout the medium as discrete spherical air bubbles occupying the voids between the particles. However, their derivation of the air pressure inside these gas bubbles is inconsistent with their stated assumptions. In addition the resultant dependence of gas pressure on liquid saturation lies outside of the plausible range of possible values for discrete air bubbles. This results in an over-prediction of the average bulk modulus of the void phase. Corrected equations are presented.

Touch-mode capacitive pressure sensor with graphene-polymer heterostructure membrane

NASA Astrophysics Data System (ADS)

Berger, Christian; Phillips, Rory; Pasternak, Iwona; Sobieski, Jan; Strupinski, Wlodek; Vijayaraghavan, Aravind

2018-01-01

We describe the fabrication and characterisation of a touch-mode capacitive pressure sensor (TMCPS) with a robust design that comprises a graphene-polymer heterostructure film, laminated onto the silicon dioxide surface of a silicon wafer, incorporating a SU-8 spacer grid structure. The spacer grid structure allows the flexible graphene-polymer film to be partially suspended above the substrate, such that a pressure on the membrane results in a reproducible deflection, even after exposing the membrane to pressures over 10 times the operating range. Sensors show reproducible pressure transduction in water submersion at varying depths under static and dynamic loading. The measured capacitance change in response to pressure is in good agreement with an analytical model of clamped plates in touch mode. The device shows a pressure sensitivity of 27.1 +/- 0.5 fF Pa-1 over a pressure range of 0.5 kPa-8.5 kPa. In addition, we demonstrate the operation of this device as a force-touch sensor in air.

Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model.

PubMed

Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

2016-01-01

The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin.

Fischer-Tropsch activity for non-promoted cobalt-on-alumina catalysts

DOEpatents

Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

2001-01-01

Cobalt catalysts, and processes employing these inventive catalysts, for hydrocarbon synthesis. The inventive catalyst comprises cobalt on an alumina support and is not promoted with any noble or near noble metals. In one aspect of the invention, the alumina support preferably includes a dopant in an amount effective for increasing the activity of the inventive catalyst. The dopant is preferably a titanium dopant. In another aspect of the invention, the cobalt catalyst is preferably reduced in the presence of hydrogen at a water vapor partial pressure effective to increase the activity of the cobalt catalyst for hydrocarbon synthesis. The water vapor partial pressure is preferably in the range of from 0 to about 0.1 atmospheres.

Uranium plasma emission coefficient in the visible and near UV.

NASA Technical Reports Server (NTRS)

Mack, J. M., Jr.; Usher, J. L.; Schneider, R. T.; Campbell, H. D.

1971-01-01

Measurements of the specific emission coefficient in the near ultra-violet and visible region of a uranium arc plasma are reported. Spatial unfolding of the intensity profile is used to determine the emission coefficient in the spectral range of 2000 A to 6000 A. The uranium partial pressure is estimated to range between .001 and .01 atmosphere, and the corresponding temperature range is 5000 - 10,000 K.

Effect of adding postoperative noninvasive ventilation to usual care to prevent pulmonary complications in patients undergoing coronary artery bypass grafting: a randomized controlled trial.

PubMed

Al Jaaly, Emad; Fiorentino, Francesca; Reeves, Barnaby C; Ind, Philip W; Angelini, Gianni D; Kemp, Scott; Shiner, Robert J

2013-10-01

We compared the efficacy of noninvasive ventilation with bilevel positive airway pressure added to usual care versus usual care alone in patients undergoing coronary artery bypass grafting. We performed a 2-group, parallel, randomized controlled trial. The primary outcome was time until fit for discharge. Secondary outcomes were partial pressure of carbon dioxide, forced expiratory volume in 1 second, atelectasis, adverse events, duration of intensive care stay, and actual postoperative stay. A total of 129 patients were randomly allocated to bilevel positive airway pressure (66) or usual care (63). Three patients allocated to bilevel positive airway pressure withdrew. The median duration of bilevel positive airway pressure was 16 hours (interquartile range, 11-19). The median duration of hospital stay until fit for discharge was 5 days for the bilevel positive airway pressure group (interquartile range, 4-6) and 6 days for the usual care group (interquartile range, 5-7; hazard ratio, 1.68; 95% confidence interval, 1.08-2.31; P = .019). There was no significant difference in duration of intensive care, actual postoperative stay, and mean percentage of predicted forced expiratory volume in 1 second on day 3. Mean partial pressure of carbon dioxide was significantly reduced 1 hour after bilevel positive airway pressure application, but there was no overall difference between the groups up to 24 hours. Basal atelectasis occurred in 15 patients (24%) in the usual care group and 2 patients (3%) in the bilevel positive airway pressure group. Overall, 30% of patients in the bilevel positive airway pressure group experienced an adverse event compared with 59% in the usual care group. Among patients undergoing elective coronary artery bypass grafting, the use of bilevel positive airway pressure at extubation reduced the recovery time. Supported by trained staff, more than 75% of all patients allocated to bilevel positive airway pressure tolerated it for more than 10 hours. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Sickling of red blood cells through rapid oxygen exchange in microfluidic drops.

PubMed

Abbyad, Paul; Tharaux, Pierre-Louis; Martin, Jean-Louis; Baroud, Charles N; Alexandrou, Antigoni

2010-10-07

We have developed a microfluidic approach to study the sickling of red blood cells associated with sickle cell anemia by rapidly varying the oxygen partial pressure within flowing microdroplets. By using the perfluorinated carrier oil as a sink or source of oxygen, the oxygen level within the water droplets quickly equilibrates through exchange with the surrounding oil. This provides control over the oxygen partial pressure within an aqueous drop ranging from 1 kPa to ambient partial pressure, i.e. 21 kPa. The dynamics of the oxygen exchange is characterized through fluorescence lifetime measurements of a ruthenium compound dissolved in the aqueous phase. The gas exchange is shown to occur primarily during and directly after droplet formation, in 0.1 to 0.5 s depending on the droplet diameter and speed. The controlled deoxygenation is used to trigger the polymerization of hemoglobin within sickle red blood cells, encapsulated in drops. This process is observed using polarization microscopy, which yields a robust criterion to detect polymerization based on transmitted light intensity through crossed polarizers.

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a catheter-tip...

In situ metrology to characterize water vapor delivery during atomic layer deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmido, Tariq, E-mail: tariq.ahmido@nist.gov; Kimes, William A.; Sperling, Brent A.

Water is often employed as the oxygen source in metal oxide atomic layer deposition (ALD) processes. It has been reported that variations in the amount of water delivered during metal oxide ALD can impact the oxide film properties. Hence, one contribution to optimizing metal oxide ALD processes would be to identify methods to better control water dose. The development of rapid, quantitative techniques for in situ water vapor measurements during ALD processes would be beneficial to achieve this goal. In this report, the performance of an in situ tunable diode laser absorption spectroscopy (TDLAS) scheme for performing rapid, quantitative watermore » partial pressure measurements in a representative quarter-inch ALD delivery line is described. This implementation of TDLAS, which utilizes a near-infrared distributed-feedback diode laser and wavelength modulation spectroscopy, provides measurements of water partial pressure on a timescale comparable to or shorter than the timescale of the gas dynamics in typical ALD systems. Depending on the degree of signal averaging, this TDLAS system was capable of measuring the water partial pressure with a detection limit in the range of ∼0.80 to ∼0.08 Pa. The utility of this TDLAS scheme was demonstrated by using it to identify characteristics of a representative water delivery system that otherwise would have been difficult to predict. Those characteristics include (1) the magnitude and time dependence of the pressure transient that can occur during water injection, and (2) the dependence of the steady-state water partial pressure on the carrier gas flow rate and the setting of the water ampoule flow restriction.« less

Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model

PubMed Central

Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

2016-01-01

Objective The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. Methods The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Results Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). Conclusion In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin. PMID:27096671

Study of the phase transformations and equation of state of magnesium by synchrotron x-ray diffraction

NASA Astrophysics Data System (ADS)

Errandonea, Daniel; Meng, Yue; Häusermann, Daniel; Uchida, Takeyuki

2003-03-01

We studied the phase behaviour and the P - V - T equation of state of Mg by in situ energy-dispersive x-ray diffraction in a multi-anvil apparatus in the pressure-temperature range up to 18.6 GPa and 1527 K. At high temperatures, an hcp to dhcp transition was found above 9.6 GPa, which differs from the hcp to bcc transformation predicted by theoretical calculations. At room temperature, the hcp phase remains stable within the pressure range of this study with an axial ratio, c/a, close to the ideal. The melting of Mg was determined at 2.2, 10 and 12 GPa; the detected melting temperatures are in good agreement with previous diamond anvil cell results. The P - V - T equation of state determined based on the data of this study gives B0 = (36.8 ± 3) GPa, B0 ' = 4.3 ± 0.4, alpha0 = 25 × 10-6 K-1, partialalpha/partialT = (2.3 ± 0.2) × 10-7 K-2 and partialB0,T /partialT = (-2.08 ± 0.09) × 10-2 GPa K-1.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kagan, D. N., E-mail: d.n.kagan@mtu-net.ru; Krechetova, G. A.; Shpil'rain, E. E.

A detailed procedural analysis is given and results of implementation of the new version of the effusion method for determining the Gibbs energy (thermodynamic activity) of binary and ternary systems of alkali metals Cs-Na, K-Na, Cs-K, and Cs-K-Na are presented. The activity is determined using partial pressures of the components measured according the effusion method by the intensity of their atomic beams. The pressure range used in the experiment is intermediate between the Knudsen and hydrodynamic effusion modes. A generalized version of the effusion method involves the pressure range beyond the limits of the applicability of the Hertz-Knudsen equation. Employmentmore » of this method provides the differential equation of chemical thermodynamics; solution of this equation makes it possible to construct the Gibbs energy in the range of temperatures 400 {<=} T {<=} 1200 K and concentrations 0 {<=} x{sub i} {<=} 1.« less

Uptake of HNO3 on water-ice and coadsorption of HNO3 and HCl in the temperature range 210-235 K

NASA Astrophysics Data System (ADS)

Hynes, Robert G.; Fernandez, Miguel A.; Cox, R. Anthony

2002-12-01

The uptake of HNO3 on water-ice films was investigated in a coated wall flow reactor under tropospheric temperature conditions. Experiments were performed in the "ice" region of the HNO3-H2O phase diagram. With HNO3 partial pressures in the range of (0.3-2.0) × 10-6 Torr, continuous uptake was observed below 215 K; whereas above 215 K, the uptake was time dependent. Using the geometric surface area of the ice film, the surface coverage at 218 K was 3.0 × 1014 molecules/cm2, decreasing to 1.5 × 1014 molecules/cm2 at 233 K; the timescales for saturation were 700 and 800 s at 218 and 233 K, respectively. The surface coverage was found to change by a factor of 2 over a 10-fold change in HNO3 partial pressure. By assuming that the surface coverage can be represented by a Langmuir isotherm for dissociative adsorption, the enthalpy of adsorption of HNO3 onto ice was found to be -(54.0 ± 2.6) kJ/mol. At a constant HNO3 partial pressure, the maximum uptake coefficients, γ, were measured as a function of temperature, decreasing from 0.03 at 215 K down to 0.006 at 235 K. The uptake coefficients at 218 K were not significantly affected by changes in HNO3 partial pressure. The uptake of HCl at 218 K on ice surfaces previously dosed with HNO3 was found to be reversible, and the coadsorption of HNO3 with HCl indicates that HCl is displaced from surface sites by HNO3 molecules. Uptake of HNO3 on HCl-dosed surfaces showed that HNO3 molecules displace ˜1013 molecules/cm3 of HCl. The efficiency of cirrus clouds in scavenging HNO3 is discussed, as well as the implications for chlorine activation reactions under tropospheric temperature conditions.

21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid in...

21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid in...

21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid in...

21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid in...

21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid in...

Cold air performance of a tip turbine designed to drive a lift fan. 2: Partial admission

NASA Technical Reports Server (NTRS)

Haas, J. E.; Kofskey, M. G.; Hotz, G. M.; Futral, S. M., Jr.

1977-01-01

Partial admission performance was obtained for a 0.4 linear scale version of the LF460 lift fan turbine over a range of speed from 40 to 140 percent of design equivalent speed and a range of scroll inlet total to diffuser exit static pressure ratio from 2.2 to 5.0. The investigation was conducted in two parts, with each part using a different side of the turbine scroll to simulate loss of a gas generator. Each side had an arc of admission of 180. Results are presented in terms of specific work, torque, mass flow, and efficiency.

Standard partial molar volumes of some aqueous alkanolamines and alkoxyamines at temperatures up to 325 degrees C: functional group additivity in polar organic solutes under hydrothermal conditions.

PubMed

Bulemela, E; Tremaine, Peter R

2008-05-08

Apparent molar volumes of dilute aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), N,N-dimethylethanolamine (DMEA), ethylethanolamine (EAE), 2-diethylethanolamine (2-DEEA), and 3-methoxypropylamine (3-MPA) and their salts were measured at temperatures from 150 to 325 degrees C and pressures as high as 15 MPa. The results were corrected for the ionization and used to obtain the standard partial molar volumes, Vo2. A three-parameter equation of state was used to describe the temperature and pressure dependence of the standard partial molar volumes. The fitting parameters were successfully divided into functional group contributions at all temperatures to obtain the standard partial molar volume contributions. Including literature results for alcohols, carboxylic acids, and hydroxycarboxylic acids yielded the standard partial molar volume contributions of the functional groups >CH-, >CH2, -CH3, -OH, -COOH, -O-, -->N, >NH, -NH2, -COO-Na+, -NH3+Cl-, >NH2+Cl-, and -->NH+Cl- over the range (150 degrees C

Two Regimes of Bandgap Red Shift and Partial Ambient Retention in Pressure-Treated Two-Dimensional Perovskites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Gang; Kong, Lingping; Guo, Peijun

The discovery of elevated environmental stability in two-dimensional (2D) Ruddlesden–Popper hybrid perovskites represents a significant advance in low-cost, high-efficiency light absorbers. In comparison to 3D counterparts, 2D perovskites of organo-lead-halides exhibit wider, quantum-confined optical bandgaps that reduce the wavelength range of light absorption. Here, we characterize the structural and optical properties of 2D hybrid perovskites as a function of hydrostatic pressure. We observe bandgap narrowing with pressure of 633 meV that is partially retained following pressure release due to an atomic reconfiguration mechanism. We identify two distinct regimes of compression dominated by the softer organic and less compressible inorganic sublattices.more » Our findings, which also include PL enhancement, correlate well with density functional theory calculations and establish structure–property relationships at the atomic scale. These concepts can be expanded into other hybrid perovskites and suggest that pressure/strain processing could offer a new route to improved materials-by-design in applications.« less

Low-pressure oxidation of Cb-1Zr alloy.

NASA Technical Reports Server (NTRS)

Lyon, T. F.

1971-01-01

Resistively heated strip specimens of Cb-1Zr alloy were exposed at 927 C in a vacuum chamber at various levels of total pressure in the 1-microtorr range and at various oxygen partial pressures in the .1-microtorr range. Oxygen reaction rates (sticking probabilities) were found to depend on whether or not the specimens were annealed immediately before the test exposure. It is shown that a normally undetectable oxide film exists on the Cb-1Zr surface as a result of oxidation by ambient air, and this film reduces the sticking probability as compared with a clean metal surface. The alloy is considerably strengthened by addition of oxygen to a level of about 6000 ppm, while still maintaining reasonably good room temperature ductility.

Neutron and X-ray investigations of the Jahn–Teller switch in partially deuterated ammonium copper Tutton salt, (NH 4 ) 2 [Cu(H 2 O) 6 ](SO 4 ) 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jørgensen, Mads R. V.; Piccoli, Paula M. B.; Hathwar, Venkatesha R.

2017-01-31

The structural phase transition accompanied by a Jahn–Teller switch has been studied over a range of H/D ratios in (NH 4) 2[Cu(H 2O) 6](SO 4) 2(ACTS). In particular, single-crystal neutron diffraction investigations of crystals with deuteration in the range 50 to 82% are shown to be consistent with previous electron paramagnetic resonance (EPR) experiments exhibiting a phase boundary at 50% deuteration under ambient pressure. Polycrystalline samples show that the two phases can co-exist. In addition, single-crystal neutron and polycrystalline X-ray diffraction pressure experiments show a shift to lower pressure at 60% deuterationversusprevious measurements at 100% deuteration.

Phase equilibria constraints on models of subduction zone magmatism

NASA Astrophysics Data System (ADS)

Myers, James D.; Johnston, Dana A.

Petrologic models of subduction zone magmatism can be grouped into three broad classes: (1) predominantly slab-derived, (2) mainly mantle-derived, and (3) multi-source. Slab-derived models assume high-alumina basalt (HAB) approximates primary magma and is derived by partial fusion of the subducting slab. Such melts must, therefore, be saturated with some combination of eclogite phases, e.g. cpx, garnet, qtz, at the pressures, temperatures and water contents of magma generation. In contrast, mantle-dominated models suggest partial melting of the mantle wedge produces primary high-magnesia basalts (HMB) which fractionate to yield derivative HAB magmas. In this context, HMB melts should be saturated with a combination of peridotite phases, i.e. ol, cpx and opx, and have liquid-lines-of-descent that produce high-alumina basalts. HAB generated in this manner must be saturated with a mafic phase assemblage at the intensive conditions of fractionation. Multi-source models combine slab and mantle components in varying proportions to generate the four main lava types (HMB, HAB, high-magnesia andesites (HMA) and evolved lavas) characteristic of subduction zones. The mechanism of mass transfer from slab to wedge as well as the nature and fate of primary magmas vary considerably among these models. Because of their complexity, these models imply a wide range of phase equilibria. Although the experiments conducted on calc-alkaline lavas are limited, they place the following limitations on arc petrologic models: (1) HAB cannot be derived from HMB by crystal fractionation at the intensive conditions thus far investigated, (2) HAB could be produced by anhydrous partial fusion of eclogite at high pressure, (3) HMB liquids can be produced by peridotite partial fusion 50-60 km above the slab-mantle interface, (4) HMA cannot be primary magmas derived by partial melting of the subducted slab, but could have formed by slab melt-peridotite interaction, and (5) many evolved calc-alkaline lavas could have been formed by crystal fractionation at a range of crustal pressures.

Proximate nutritional composition of CELSS crops grown at different CO2 partial pressures

NASA Technical Reports Server (NTRS)

Wheeler, R. M.; Mackowiak, C. L.; Sager, J. C.; Knott, W. M.; Berry, W. L.

1994-01-01

Two Controlled Ecological Life Support System (CELSS) candidate crops, soybean (Glycine max) and potato (Solanum tuberosum), were grown hydroponically in controlled environments maintained at carbon dioxide (CO2) partial pressures ranging from 0.05 to 1.00 kPa (500 to 10,000 ppm at 101 kPa atmospheric pressure). Plants were harvested at maturity (90 days for soybean and 105 days for potato) and all tissues analyzed for proximate nutritional composition (i.e. protein, fat, carbohydrate, crude fiber, and ash content). Soybean seed ash and crude fiber were higher and carbohydrate was lower than values reported for field-grown seed. Potato tubers showed little difference from field-grown tubers. Crude fiber of soybean stems and leaves increased with increased CO2, as did soybean leaf protein (total nitrogen). Potato leaf and stem (combined) protein levels also increased with increased CO2, while leaf and stem carbohydrates decreased. Values for leaf and stem protein and ash were higher than values generally reported for field-grown plants for both species. Results suggest that CO2 partial pressure should have little influence on proximate composition of potato tubers or soybean seed, but that high ash and protein levels might be expected from leaves and stems of crops grown in controlled environments of a CELSS.

Compositional dependent partial molar volume and compressibility of CO2 in rhyolite, phonolite and basalt glasses

NASA Astrophysics Data System (ADS)

Lerch, P.; Seifert, R.; Malfait, W. J.; Sanchez-Valle, C.

2012-12-01

Carbon dioxide is the second most abundant volatile in magmatic systems and plays an important role in many magmatic processes, e.g. partial melting, volatile saturation, outgassing. Despite this relevance, the volumetric properties of carbon-bearing silicates at relevant pressure and temperature conditions remain largely unknown because of considerable experimental difficulties associated with in situ measurements. Density and elasticity measurements on quenched glasses can provide an alternative source of information. For dissolved water, such measurements indicate that the partial molar volume is independent of compositions at ambient pressure [1], but the partial molar compressibility is not [2, 3]. Thus the partial molar volume of water may depend on melt composition at elevated pressure. For dissolved CO2, no such data is available. In order to constrain the effect of magma composition on the partial molar volume and compressibility of dissolved carbon, we determined the density and elasticity for three series of carbon-bearing basalt, phonolite and rhyolite glasses, quenched from 3.5 GPa and relaxed at ambient pressure. The CO2 content varies between 0 to 3.90 wt% depending on the glass composition. Glass densities were determined using the sink/float method in a diiodomethane (CH2I2) - acetone mixture. Brillouin measurements were conducted on relaxed and unrelaxed silicate glasses in platelet geometry to determine the compressional (VP) and shear (VS) wave velocities and elastic moduli. The partial molar volume of CO2 in rhyolite, phonolite and basalt glasses is 25.4 ± 0.9, 22.1 ± 0.6 and 26.6 ±1.8 cm3/mol, respectively. Thus, unlike for dissolved water, the partial molar volume of CO2 displays a resolvable compositional effect. Although the composition and CO2/carbonate speciation of the phonolite glasses is intermediate between that of the rhyolite and basalt glasses, the molar volume is not. Similar to dissolved water, the partial molar bulk modulus of CO2 displays a strong compositional effect. If these compositional dependencies persist in the analogue melts, the partial molar volume of dissolved CO2 will depend on melt composition, both at low and elevated pressure. Thus, for CO2-bearing melts, a full quantitative understanding of density dependent magmatic processes, such as crystal fractionation, magma mixing and melt extraction will require in situ measurements for a range of melt compositions. [1] Richet, P. et al., 2000, Contrib Mineral Petrol, 138, 337-347. [2] Malfait et al. 2011, Am. Mineral. 96, 1402-1409. [3] Whittington et al., 2012, Am. Mineral. 97, 455-467.

Gd Ba Cu O bulk superconductors fabricated by a seeded infiltration growth technique under reduced oxygen partial pressure

NASA Astrophysics Data System (ADS)

Iida, K.; Babu, N. H.; Shi, Y. H.; Cardwell, D. A.; Murakami, M.

2006-06-01

Single-grain Gd-Ba-Cu-O (GdBCO) bulk superconductors have been grown by a seeded infiltration and growth (SIG) technique under a 1% O2+N2 atmosphere using a generic MgO-doped Nd-Ba-Cu-O (MgO-NdBCO) seed placed on the sample surface at room temperature (the so-called the cold-seeding method). Partial melting of the MgO-NdBCO seeds fabricated in air under notionally identical thermal processing conditions, however, limited the reliability of this bulk GdBCO single-grain process. The observed seed decomposition is attributed to the dependence of the peritectic temperature Tp of MgO-doped Nd1+xBa2-xCu3Oy solid solution (MgO-doped Nd-123ss, where ss indicates solid solution) compounds on both oxygen partial pressure during the melt process and the level of solid solution (x). The peritectic decomposition temperature of MgO-doped Nd-123ss, with x ranging from 0 to 0.5 under p(O2) = 1.00 atm, was observed to remain constant at 1120 °C. Tp was observed to decrease linearly as a function of solid solution level, on the other hand, under oxygen partial pressures of both p(O2) = 0.21 and 0.01 atm. Based on these results, MgO-doped NdBCO seed crystals should be grown under reduced oxygen partial pressure in order to obtain a stable MgO-doped NdBCO seed crystal suitable for cold-seeding processes of large-grain (RE)BCO bulk superconductors (where RE is a rare earth element).

Absorption of Carbon Dioxide in the aqueous solution of Diethanolamine (DEA) blended with 1-Butyl-1-Methylpyrrolidinium Trifluoromethanesulfonate [BmPyrr][OTf] at high pressure

NASA Astrophysics Data System (ADS)

Jamaludin, S. N.; Salleh, R. M.

2018-03-01

Solubility data of carbon dioxide (CO2) in aqueous Diethanolamine (DEA) blended with 1-Butyl-1-Methylpyrrolidinium Trifluoromethanesulfonate [Bmpyrr][OTf] were measured at temperature 313.15K, 323.15K, 333.15K and pressure from 500psi up to 700 psi. The experiments covered over the concentration range of 0-10wt% for [Bmpyrr][OTf] and 30-40wt% for DEA. The solubility of CO2 was evaluated by measuring the pressure drop in high pressure stirred absorption cell reactor. The experimental results showed that CO2 loading in all DEA-[BmPyrr][OTf] mixtures studied increases with increasing of CO2 partial pressure and temperature. It was also found that the CO2 loading capacity increase significantly as the concentration of [Bmpyrr][OTf] increases. Jou and Mather model was used to predict the solubility of CO2 in the mixtures where the experimental data were correlated as a function of temperature and CO2 partial pressure. It was found that the model was successful in predicting the solubility behavior of the aqueous DEA-[Bmpyrr][OTf] systems considered in this study.

One-man electrochemical air revitalization system evaluation

NASA Technical Reports Server (NTRS)

Schbert, F. H.; Marshall, R. D.; Hallick, T. M.; Woods, R. R.

1976-01-01

A program to evaluate the performance of a one man capacity, self contained electrochemical air revitalization system was successfully completed. The technology readiness of this concept was demonstrated by characterizing the performance of this one man system over wide ranges in cabin atmospheric conditions. The electrochemical air revitalization system consists of a water vapor electrolysis module to generate oxygen from water vapor in the cabin air, and an electrochemical depolarized carbon dioxide concentrator module to remove carbon dioxide from the cabin air. A control/monitor instrumentation package that uses the electrochemical depolarized concentrator module power generated to partially offset the water vapor electrolysis module power requirements and various structural fluid routing components are also part of the system. The system was designed to meet the one man metabolic oxygen generation and carbon dioxide removal requirements, thereby controlling cabin partial pressure of oxygen at 22 kN/sq m and cabin pressure of carbon dioxide at 400 N/sq m over a wide range in cabin air relative humidity conditions.

Vapor-liquid-solid epitaxial growth of Si 1-xGe x alloy nanowires. Composition dependence on precursor reactivity and morphology control for vertical forests

DOE PAGES

Choi, S. G.; Manandhar, P.; Picraux, S. T.

2015-07-07

The growth of high-density group IV alloy nanowire forests is critical for exploiting their unique functionalities in many applications. Here, the compositional dependence on precursor reactivity and optimized conditions for vertical growth are studied for Si 1- x Ge x alloy nanowires grown by the vapor-liquid-solid method. The nanowire composition versus gas partial-pressure ratio for germane-silane and germane-disilane precursor combinations is obtained at 350°C over a wide composition range (0.05 ≤ x ≤ 0.98) and a generalized model to predict composition for alloy nanowires is developed based on the relative precursor partial pressures and reactivity ratio. In combination with germane,more » silane provides more precise compositional control at high Ge concentrations (x > 0.7), whereas disilane greatly increases the Si concentration for a given gas ratio and enables more precise alloy compositional control at small Ge concentrations (x < 0.3). Vertically oriented, non-kinking nanowire forest growth on Si (111) substrates is then discussed for silane/germane over a wide range of compositions, with temperature and precursor partial pressure optimized by monitoring the nanowire growth front using in-situ optical reflectance. For high Ge compositions (x ≈ 0.9), a “two-step” growth approach with nucleation at higher temperatures results in nanowires with high-density and uniform vertical orientation. Furthermore, increasing Si content (x ≈ 0.8), the optimal growth window is shifted to higher temperatures, which minimizes nanowire kinking morphologies. For Si-rich Si 1- x Ge x alloys (x ≈ 0.25), vertical nanowire growth is enhanced by single-step, higher-temperature growth at reduced pressures.« less

Modeling of termokinetic oscillations at partial oxidation of methane

NASA Astrophysics Data System (ADS)

Arutyunov, A. V.; Belyaev, A. A.; Inovenkov, I. N.; Nefedov, V. V.

2017-12-01

Partial oxidation of natural gas at moderate temperatures below 1500 K has significant interest for a number of industrial applications. But such processes can proceed at different unstable regimes including oscillating modes. Nonlinear phenomena at partial oxidation of methane were observed at different conditions. The investigation of the complex nonlinear system of equations that describes this process is a real method to insure its stability at industrial conditions and, at the same time, is an effective tool for its further enhancement. Numerical analysis of methane oxidation kinetics in the continuous stirred-tank reactor, with the use of detailed kinetic model has shown the possibility of the appearance of oscillating modes in the appropriate range of reaction parameters that characterize the composition, pressure, reagents flow, thermophysical features of the system, and geometry of the reactor. The appearance of oscillating modes is connected both with the reaction kinetics, heat release and sink and reagents introduction and removing. At that, oscillations appear only at a limited range of parameters, but can be accompanied by significant change in the yield of products. We have determined the range of initial temperature and pressure at which oscillations can be observed, if all other parameters remained fixed. The boundaries of existence of oscillations on the phase plane were calculated. It was shown that depending on the position inside the oscillation region the oscillations have different frequency and amplitude. It was reviled the role of heat exchange with the environment: at the absence of heat exchange the oscillating modes are impossible. In the vicinity of the boundary of phase range, where oscillations exist, significant change of concentration of some products were observed, for example, that of CO2, which in this case one of the principal products is. At that, insignificant increase in pressure not only change the character of CO2 behaving with time, but as well lead to significant increase of its mole fraction simultaneously twice decreasing the mole fraction of CO.

[Pedicled superior gluteal artery perforator bilateral quadrilobed flaps for repair of large sacrococcygeal pressure sores].

PubMed

Hai, Henglin; Li, Huatao; Chen, Yang; Li, Qiang; Wu, Shenggang; Lili, Wang; Yan, Lei; Xiaoying, Zhou

2013-03-01

To investigate the effectiveness of pedicled superior gluteal artery perforator bilateral quadrilobed flaps for repairing large sacrococcygeal pressure sores. Between June 2003 and August 2011, 6 paraplegia patients with large sacrococcygeal pressure sores were repaired with the pedicled superior gluteal artery perforator bilateral quadrilobed flaps. There were 2 males and 4 females with an average age of 45.6 years (range, 37-62 years). The mean disease duration was 8.4 months (range, 3-26 months). According to National Pressure Ulcer Advisory Panel (NPUAP) standard, 6 cases rated as degree IV. The size of pressure sores ranged from 15 cm x 13 cm to 18 cm x 16 cm. The size of flaps ranged from 18 cm x 14 cm to 21 cm x 15 cm. After operation, all flaps survived successfully. The wounds healed by first intention in 5 cases; partial dehiscence of incision occurred in 1 case, which was cured after dressing change for 26 days. Six patients were followed up 6-24 months (mean, 12.5 months). The appearance and texture of the flaps were smooth and soft with good elasticity and no ulceration. Pedicled superior gluteal artery perforator bilateral quadrilobed flaps can repair large sacrococcygeal pressure sores. The appearance of flaps is smooth and has good compression-resistance effect.

Partial Pressures of Te2 and Thermodynamic Properties of Ga-Te System

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Curreri, Peter A. (Technical Monitor)

2001-01-01

The partial pressures of Te2 in equilibrium with Ga(1-x)Te(x) samples were measured by optical absorption technique from 450 to 1100 C for compositions, x, between 0.333 and 0.612. To establish the relationship between the partial pressure of Te, and the measured optical absorbance, the calibration runs of a pure Te sample were also conducted to determine the Beer's Law constants. The partial pressures of Te2 in equilibrium with the GaTe(s) and Ga2Te3(s)compounds, or the so-called three-phase curves, were established. These partial pressure data imply the existence of the Ga3Te4(s) compound. From the partial pressures of Te2 over the Ga-Te melts, partial molar enthalpy and entropy of mixing for Te were derived and they agree reasonable well with the published data. The activities of Te in the Ga-Te melts were also derived from the measured partial pressures of Te2. These data agree well with most of the previous results. The possible reason for the high activity of Te measured for x less than 0.60 is discussed.

FirefOx Design Reference fO2 Sensor for Hot, Deep Atmospheres

NASA Astrophysics Data System (ADS)

Izenberg, N.; Papadakis, S.; Deglau, D.; Francomacaro, A. S.

2016-12-01

Understanding the composition of the lowest portion of Venus' atmosphere is critical to knowing the stable mineralogy of the rocks there. Oxygen gas is a critical trace component, with fugacity, or partial pressure, estimated in the range of 10-19 to 10-22 from early probe measurements down to 22km altitude (Pioneer Venus, Venera), chemical equilibrium measurements, and other modeling. "FirefOx" is a simple oxygen fugacity sensor with the express purpose of determining the partial pressure of oxygen in the lowest scale heights of the Venus atmosphere, and especially the lowest hundreds of meters; the surface atmosphere interface, where the atmosphere and surface move to thermodynamic equilibrium. Knowledge of the fO2 at the surface atmosphere interface is crucial to determining the stable mineralogy of surface materials (e.g. magnetite vs. hematite) and gas chemistry in the near-surface atmosphere FirefOx is a Metal/Metal Oxide oxygen fugacity sensor intended to be mounted on the outside of a Venus descent probe, with electronics housed inside a thermally controlled environment. The sole sensor capability is the precise, accurate detection of the partial pressure of oxygen gas (fO2) in the near-surface environment of Venus, at up to 95-bar pressure (predominantly CO2. Surface temperatures at mean planetary elevation are near 735 K, thus a required operational temperature range of 710-740 K covers a range of near-surface elevations. FirefOx system requirements are low ( 100-200 grams, mass, milliwatt power, several kilobytes total science data). A design reference sensor, composed of custom, Yittria-ZrO ceramic electrolyte, with an encapsulated Pd/PdO standard and patterned Pt electrodes has demonstrated scientifically useful signal-to-noise millivolt level potential at temperatures as low as 620 K, relatable to fO2 by a Nernst equation E = RT/4F ln(PO2/PrefO2) where E = open circuit potential across the sensor electrolyte, R = universal gas constant, T = temperature, F = Faraday constant, PrefO2 = reference oxygen pressure, and PO2 = unknown oxygen pressure of the outside environment. The FirefOx sensor shows promise for direct fO2 measurement on potential upcoming Venus in situ and other deep atmosphere probes.

Environmental Resistance in the Mars Atmosphere

NASA Astrophysics Data System (ADS)

Pint, Bruce A.; Tortorelli, Peter F.

2005-02-01

The atmosphere of Mars is ~6mbar of total pressure (compared to ~1 bar on Earth) and 95%CO2. Thermodynamic calculations have been made of the partial pressure of oxygen as a function of temperature assuming various impurities in the remaining 5%. These oxygen pressures are sufficient to oxidize most common metals in the 900-1300K range. Therefore, oxidation resistance will be a concern for materials of construction in a high temperature fission reactor on Mars. An additional environmental resistance consideration is internal carburization during exposures in CO2. The effect of low pressure CO2 exposures on the mechanical properties of austenitic alloys is being investigated.

Determination of Activities of Niobium in Cu-Nb Melts Containing Dilute Nb

NASA Astrophysics Data System (ADS)

Wang, Daya; Yan, Baijun; Sichen, Du

2015-04-01

The activity coefficients of niobium in Cu-Nb melts were measured by equilibrating solid NbO2 with liquid copper under controlled oxygen potentials in the temperature range of 1773 K to 1898 K (1500 °C to 1625 °C). Either CO-CO2 gas mixture or H2-CO2 gas mixture was employed to obtain the desired oxygen partial pressures. Cu-Nb system was found to follow Henry's law in the composition range studied. The temperature dependence of Henry's constant in the Cu-Nb melts could be expressed as follows: The partial molar excess Gibbs energy change of niobium in Cu-Nb melts can be expressed as follows:

Chlorination of lanthanum oxide.

PubMed

Gaviría, Juan P; Navarro, Lucas G; Bohé, Ana E

2012-03-08

The reactive system La(2)O(3)(s)-Cl(2)(g) was studied in the temperature range 260-950 °C. The reaction course was followed by thermogravimetry, and the solids involved were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the reaction leads to the formation of solid LaOCl, and for temperatures above 850 °C, the lanthanum oxychloride is chlorinated, producing LaCl(3)(l). The formation of the oxychloride progresses through a nucleation and growth mechanism, and the kinetic analysis showed that at temperatures below 325 °C the system is under chemical control. The influence of diffusive processes on the kinetics of production of LaOCl was evaluated by studying the effect of the reactive gas flow rate, the mass of the sample, and the chlorine diffusion through the boundary layer surrounding the solid sample. The conversion curves were analyzed and fitted according to the Johnson-Mehl-Avrami description, and the reaction order with respect to the chlorine partial pressure was obtained by varying this partial pressure between 10 and 70 kPa. The rate equation was obtained, which includes the influence of the temperature, chlorine partial pressure, and reaction degree.

Studying pressure denaturation of a protein by molecular dynamics simulations.

PubMed

Sarupria, Sapna; Ghosh, Tuhin; García, Angel E; Garde, Shekhar

2010-05-15

Many globular proteins unfold when subjected to several kilobars of hydrostatic pressure. This "unfolding-up-on-squeezing" is counter-intuitive in that one expects mechanical compression of proteins with increasing pressure. Molecular simulations have the potential to provide fundamental understanding of pressure effects on proteins. However, the slow kinetics of unfolding, especially at high pressures, eliminates the possibility of its direct observation by molecular dynamics (MD) simulations. Motivated by experimental results-that pressure denatured states are water-swollen, and theoretical results-that water transfer into hydrophobic contacts becomes favorable with increasing pressure, we employ a water insertion method to generate unfolded states of the protein Staphylococcal Nuclease (Snase). Structural characteristics of these unfolded states-their water-swollen nature, retention of secondary structure, and overall compactness-mimic those observed in experiments. Using conformations of folded and unfolded states, we calculate their partial molar volumes in MD simulations and estimate the pressure-dependent free energy of unfolding. The volume of unfolding of Snase is negative (approximately -60 mL/mol at 1 bar) and is relatively insensitive to pressure, leading to its unfolding in the pressure range of 1500-2000 bars. Interestingly, once the protein is sufficiently water swollen, the partial molar volume of the protein appears to be insensitive to further conformational expansion or unfolding. Specifically, water-swollen structures with relatively low radii of gyration have partial molar volume that are similar to that of significantly more unfolded states. We find that the compressibility change on unfolding is negligible, consistent with experiments. We also analyze hydration shell fluctuations to comment on the hydration contributions to protein compressibility. Our study demonstrates the utility of molecular simulations in estimating volumetric properties and pressure stability of proteins, and can be potentially extended for applications to protein complexes and assemblies. Proteins 2010. (c) 2009 Wiley-Liss, Inc.

Evaluation of Neurophysiologic and Systematic Changes during Aeromedical Evacuation and en Route Care of Combat Casualties in a Swine Polytrauma

DTIC Science & Technology

2017-02-01

ambient conditions such as cabin pressure and temperature could potentially have detrimental effects on the already vulnerable brain. There is evidence...long-range aero-medical evacuation has adverse effects on brain blood flow and tissue oxygenation , as well as lung function in swine models of...differences in partial pressure of arterial oxygen or oxygen delivery, extraction and consumption data. This suggests that in this particular model

Dual-Band Optical Bench for Terahertz Radiometer for Outer Planet Atmospheres (TROPA)

NASA Technical Reports Server (NTRS)

Schlecht, Erich; Jamnejad, Vahraz

2012-01-01

We have developed a wide-band dual frequency spectrometer for use in deep space planetary atmospheric spectroscopy. The instrument uses a dual-band architecture, both to be able to observe spectral lines from a wide range of atmospheric species, and to allow a higher precision retrieval of temperature/pressure/partial pressure and wind profiles. This dual-band approach requires a new design for the optical bench to couple both frequencies into their respective receivers.

Oxygen Partial Pressure and Oxygen Concentration Flammability: Can They Be Correlated?

NASA Technical Reports Server (NTRS)

Harper, Susana A.; Juarez, Alfredo; Perez, Horacio, III; Hirsch, David B.; Beeson, Harold D.

2016-01-01

NASA possesses a large quantity of flammability data performed in ISS airlock (30% Oxygen 526mmHg) and ISS cabin (24.1% Oxygen 760 mmHg) conditions. As new programs develop, other oxygen and pressure conditions emerge. In an effort to apply existing data, the question arises: Do equivalent oxygen partial pressures perform similarly with respect to flammability? This paper evaluates how material flammability performance is impacted from both the Maximum Oxygen Concentration (MOC) and Maximum Total Pressures (MTP) perspectives. From these studies, oxygen partial pressures can be compared for both the MOC and MTP methods to determine the role of partial pressure in material flammability. This evaluation also assesses the influence of other variables on flammability performance. The findings presented in this paper suggest flammability is more dependent on oxygen concentration than equivalent partial pressure.

Pressure (Or No Royal Road)

ERIC Educational Resources Information Center

Bradley, J.

1973-01-01

Discusses how difficult the various problems of pressure, partial pressure, gas laws, and vapor pressure are for students. Outlines the evolution of the concept of pressure, the gas equation for a perfect gas, partial pressures, saturated vapor pressure, Avogadro's hypothesis, Raoult's law, and the vapor pressure of ideal solutions. (JR)

Sensor for measuring hydrogen partial pressure in parabolic trough power plant expansion tanks

NASA Astrophysics Data System (ADS)

Glatzmaier, Greg C.; Cooney, Daniel A.

2017-06-01

The National Renewable Energy Laboratory and Acciona Energy North America are working together to design and implement a process system that provides a permanent solution to the issue of hydrogen buildup at parabolic trough power plants. We are pursuing a method that selectively removes hydrogen from the expansion tanks that serve as reservoirs for the heat transfer fluid (HTF) that circulates in the collector field and power block components. Our modeling shows that removing hydrogen from the expansion tanks at a design rate reduces and maintains dissolved hydrogen in the circulating HTF to a selected target level. Our collaborative work consists of several tasks that are needed to advance this process concept to a development stage, where it is ready for implementation at a commercial power plant. Our main effort is to design and evaluate likely process-unit operations that remove hydrogen from the expansion tanks at a specified rate. Additionally, we designed and demonstrated a method and instrumentation to measure hydrogen partial pressure and concentration in the expansion-tank headspace gas. We measured hydrogen partial pressure in the headspace gas mixture using a palladium-alloy membrane, which is permeable exclusively to hydrogen. The membrane establishes a pure hydrogen gas phase that is in equilibrium with the hydrogen in the gas mixture. We designed and fabricated instrumentation, and demonstrated its effectiveness in measuring hydrogen partial pressures over a range of three orders of magnitude. Our goal is to install this instrument at the Nevada Solar One power plant and to demonstrate its effectiveness in measuring hydrogen levels in the expansion tanks under normal plant operating conditions.

Generation, ascent and eruption of magma on the Moon: New insights into source depths, magma supply, intrusions and effusive/explosive eruptions (Part 1: Theory)

NASA Astrophysics Data System (ADS)

Wilson, Lionel; Head, James W.

2017-02-01

We model the ascent and eruption of lunar mare basalt magmas with new data on crustal thickness and density (GRAIL), magma properties, and surface topography, morphology and structure (Lunar Reconnaissance Orbiter). GRAIL recently measured the broad spatial variation of the bulk density structure of the crust of the Moon. Comparing this with the densities of lunar basaltic and picritic magmas shows that essentially all lunar magmas were negatively buoyant everywhere within the lunar crust. Thus positive excess pressures must have been present in melts at or below the crust-mantle interface to enable them to erupt. The source of such excess pressures is clear: melt in any region experiencing partial melting or containing accumulated melt, behaves as though an excess pressure is present at the top of the melt column if the melt is positively buoyant relative to the host rocks and forms a continuously interconnected network. The latter means that, in partial melt regions, probably at least a few percent melting must have taken place. Petrologic evidence suggests that both mare basalts and picritic glasses may have been derived from polybaric melting of source rocks in regions extending vertically for at least a few tens of km. This is not surprising: the vertical extent of a region containing inter-connected partial melt produced by pressure-release melting is approximately inversely proportional to the acceleration due to gravity. Translating the ∼25 km vertical extent of melting in a rising mantle diapir on Earth to the Moon then implies that melting could have taken place over a vertical extent of up to 150 km. If convection were absent, melting could have occurred throughout any region in which heat from radioisotope decay was accumulating; in the extreme this could have been most of the mantle. The maximum excess pressure that can be reached in a magma body depends on its environment. If melt percolates upward from a partial melt zone and accumulates as a magma reservoir, either at the density trap at the base of the crust or at the rheological trap at the base of the elastic lithosphere, the excess pressure at the top of the magma body will exert an elastic stress on the overlying rocks. This will eventually cause them to fail in tension when the excess pressure has risen to close to twice the tensile strength of the host rocks, perhaps up to ∼10 MPa, allowing a dike to propagate upward from this point. If partial melting occurs in a large region deep in the mantle, however, connections between melt pockets and veins may not occur until a finite amount, probably a few percent, of melting has occurred. When interconnection does occur, the excess pressure at the top of the partial melt zone will rise abruptly to a high value, again initiating a brittle fracture, i.e. a dike. That sudden excess pressure is proportional to the vertical extent of the melt zone, the difference in density between the host rocks and the melt, and the acceleration due to gravity, and could readily be ∼100 MPa, vastly greater than the value needed to initiate a dike. We therefore explored excess pressures in the range ∼10 to ∼100 MPa. If eruptions take place through dikes extending upward from the base of the crust, the mantle magma pressure at the point where the dike is initiated must exceed the pressure due to the weight of the magmatic liquid column. This means that on the nearside the excess pressure must be at least ∼19 ± 9 MPa and on the farside must be ∼29 ± 15 MPa. If the top of the magma body feeding an erupting dike is a little way below the base of the crust, slightly smaller excess pressures are needed because the magma is positively buoyant in the part of the dike within the upper mantle. Even the smallest of these excess pressures is greater than the ∼10 MPa likely maximum value in a magma reservoir at the base of the crust or elastic lithosphere, but the values are easily met by the excess pressures in extensive partial melt zones deeper within the mantle. Thus magma accumulations at the base of the crust would have been able to intrude dikes part-way through the crust, but not able to feed eruptions to the surface; in order to be erupted, magma must have been extracted from deeper mantle sources, consistent with petrologic evidence. Buoyant dikes growing upward from deep mantle sources of partial melt can disconnect from their source regions and travel through the mantle as isolated bodies of melt that encounter and penetrate the crust-mantle density boundary. They adjust their lengths and internal pressure excesses so that the stress intensity at the lower tip is zero. The potential total vertical extent of the resulting melt body depends on the vertical extent of the source region from which it grew. For small source extents, the upper tip of the resulting dike crossing the crust-mantle boundary cannot reach the surface anywhere on the Moon and therefore can only form a dike intrusion; for larger source extents, the dike can reach the surface and erupt on the nearside but still cannot reach the surface on the farside; for even larger source extents, eruptions could occur on both the nearside and the farside. The paucity of farside eruptions therefore implies a restricted range of vertical extents of partial melt source region sizes, between ∼16 and ∼36 km. When eruptions can occur, the available pressure in excess of what is needed to support a static magma column to the surface gives the pressure gradient driving magma flow. The resulting typical turbulent magma rise speeds are ∼10 to a few tens of m s-1, dike widths are of order 100 m, and eruption rates from 1 to 10 km long fissure vents are of order 105 to 106 m3 s-1. Volume fluxes in lunar eruptions derived from lava flow thicknesses and surface slopes or rille lengths and depths are found to be of order 105 to 106 m3 s-1 for volume-limited lava flows and >104 to 105 m3 s-1 for sinuous rilles, with dikes widths of ∼50 m. The lower end of the volume flux range for sinuous rilles corresponds to magma rise speeds approaching the limit set by the fact that excessive cooling would occur during flow up a 30 km long dike kept open by a very low excess pressure. These eruptions were thus probably fed by partial melt zones deep in the mantle. Longer eruption durations, rather than any subtle topographic slope effects, appear to be the key to the ability of these flows to erode sinuous rille channels. We conclude that: (1) essentially all lunar magmas were negatively buoyant everywhere within the crust; (2) positive excess pressures of at least 20-30 MPa must have been present in mantle melts at or below the crust-mantle interface to drive magmas to the surface; (3) such pressures are easily produced in zones of partial melting by pressure-release during mantle convection or simple heat accumulation from radioisotopes; (4) magma volume fluxes available from dikes forming at the tops of partial melt zones are consistent with the 105 to 106 m3 s-1 volume fluxes implied by earlier analyses of surface flows; (5) eruptions producing thermally-eroded sinuous rille channels involved somewhat smaller volume fluxes of magma where the supply rate may be limited by the rate of extraction of melt percolating through partial melt zones.

Single-component and binary CO2 and H2O adsorption of amine-functionalized cellulose.

PubMed

Gebald, Christoph; Wurzbacher, Jan A; Borgschulte, Andreas; Zimmermann, Tanja; Steinfeld, Aldo

2014-02-18

A fundamental analysis of single-component and binary CO2 and H2O adsorption of amine-functionalized nanofibrillated cellulose is carried out in the temperature range of 283-353 K and at CO2 partial pressures in the range of 0.02-105 kPa, where the ultralow partial pressure range is relevant for the direct capture of CO2 from atmospheric air. Single-component CO2 and H2O adsorption experimental data are fitted to the Toth and Guggenheim-Anderson-de Boer models, respectively. Corresponding heats of adsorption, derived from explicit solutions of the van't Hoff equation, are -50 kJ/mol CO2 and -48.8 kJ/mol H2O. Binary CO2/H2O adsorption measurements for humid air reveal that the presence of H2O at 2.55 kPa enhances CO2 adsorption, while the presence of CO2 at 0.045 kPa does not influence H2O adsorption. The energy demand of the temperature-vacuum-swing adsorption/desorption cycle for delivering pure CO2 from air increases significantly with H2O adsorption and indicates the need to reduce the hygroscopicity of the adsorbent.

Phase equilibrium constraints on the origin of basalts, picrites, and komatiites

NASA Astrophysics Data System (ADS)

Herzberg, C.; O'Hara, M. J.

1998-07-01

Experimental phase equilibrium studies at pressures ranging from 1 atm to 10 GPa are sufficient to constrain the origin of igneous rocks formed along oceanic ridges and in hotspots. The major element geochemistry of MORB is dominated by partial crystallization at low pressures in the oceanic crust and uppermost mantle, forcing compliance with liquid compositions in low-pressure cotectic equilibrium with olivine, plagioclase and often augite too; parental magmas to MORB formed by partial melting, mixing, and pooling have not survived these effects. Similarly, picrites and komatiites can transform to basalts by partial crystallization in the crust and lithosphere. However, parental picrites and komatiites that were successful in erupting to the surface typically have compositions that can be matched to experimentally-observed anhydrous primary magmas in equilibrium with harzburgite [L+Ol+Opx] at 3.0 to 4.5 GPa. This pressure is likely to represent an average for pooled magmas that collected at the top of a plume head as it flattened below the lithosphere. There is substantial uniformity in the normative olivine content of primary magmas at all depths in a plume melt column, and this results in pooled komatiitic magmas that are equally uniform in normative olivine. However, the imposition of pressure above 3 GPa produces picrites and komatiites with variations in normative enstatite and Al 2O 3 that reveal plume potential temperature and depths of initial melting. Hotter plumes begin to melt deeper than cooler plumes, yielding picrites and komatiites that are enriched in normative enstatite and depleted in Al 2O 3 because of a deeper column within which orthopyroxene can dissolve during decompression. Pressures of initial melting span the 4 to 10 GPa range, increasing in the following order: Iceland, Hawaii, Gorgona, Belingwe, Barberton. Parental komatiites and picrites from a single plume also exhibit internal variability in normative enstatite and Al 2O 3, indicating either a poorly mixed partial melt aggregation process in the plume or the imposition of partial crystallization of olivine-orthopyroxenite on a well-mixed parental magma. Plume shape and thermal structure can also influence the petrology and geochemistry of picrites and komatiites. Liquids extracted from harzburgite residues [L+Ol+Opx] will dominate magmatism in a plume head, and can erupt to form komatiites in oceanic plateaus. Liquids extracted from garnet peridotite residues in a plume axis will gain in importance when the plume head partially solidifies and is removed from the hotspot by a moving lithosphere, as is the case for Hawaii. The paradoxical involvement of garnet indicated by the heavy rare earth elements in picrites that otherwise have a harzburgite signature in Hawaii can be explained by the mixing and collection of magmas from the plume axis. Volcanic rocks from Hawaii and Gorgona and xenoliths from cratonic mantle provide evidence for the importance of partial crystallization of plume magmas when they encounter a cold lithosphere. Harzburgite residua and olivine-orthopyroxene cumulates formed in plumes can yield compositionally distinct lithospheric mantle which is buoyant, and this could have provided an important foundation for the stabilization of the first continents.

Highly oriented NdFeCoB nanocrystalline magnets from partially disproportionated compacts by reactive deformation under low pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Qing; Li, Jun; Liu, Ying, E-mail: liuying5536@163.com

2014-05-07

In the present investigation, we take advantage of the ultrafine grain size of NdFeCoB partially hydrogen-disproportionated phases, and prepare anisotropic nanocrystalline magnets with full density and homogenous microstructure and texture by reactive deformation under low pressure. Our results suggest that the pressure could properly promote an occurrence of desorption-recombination reaction due to a shorter-range rearrangement of the atoms, and the newly recombined Nd{sub 2}Fe{sub 14}B grains with fine grain size could undergo deformation immediately after the phase transformation, and then an obvious anisotropy and uniform alignment would be obtained. The maximum magnetic properties, (BH){sub max} = 25.8 MGOe, Br = 11.8 kG, H{sub cj} = 5.5more » kOe, were obtained after being treated for 5 min at 820 °C in vacuum. The present study highlights the feasibility to prepare anisotropic nanocrystalline magnets with homogeneous microstructure and a strong (00l) texture of uniform grain size under low pressure.« less

Adsorption of 2-propanol on ice probed by ambient pressure X-ray photoelectron spectroscopy

DOE PAGES

Newberg, John T.; Bluhm, Hendrik

2015-08-18

The interaction of 2-propanol with ice was examined via ambient pressure X-ray photoelectron spectroscopy (APXPS), a surface sensitive technique that probes the adsorbed 2-propanol directly with submonolayer resolution. Isothermal uptake experiments were performed on vapor deposited ice at 227 K in the presence of the equilibrium water vapor pressure of 0.05 Torr and 2-propanol partial pressures ranging from 5 × 10 -5 to 2 × 10 -3 Torr. The C 1s APXPS spectra of adsorbed 2-propanol showed two characteristic peaks associated with the C OH alcohol group and C Me methyl groups in a 1 : 2 ratio, respectively. Coveragemore » increased with 2-propanol partial pressure and followed first order Langmuir kinetics with a Langmuir constant of K = 6.3 × 10 3 Torr -1. The 1 : 2 ratio of C OH : C Me remained constant with increasing coverage, indicating there is no chemical reaction upon adsorption. The observed Langmuir kinetics using APXPS is consistent with previous observations of other small chain alcohols via indirect adsorption methods using, e.g., Knudsen cell and coated wall flow tube reactors.« less

Parametric study of orthopedic insole of valgus foot on partial foot amputation.

PubMed

Guo, Jun-Chao; Wang, Li-Zhen; Chen, Wei; Du, Cheng-Fei; Mo, Zhong-Jun; Fan, Yu-Bo

2016-01-01

Orthopedic insole was important for partial foot amputation (PFA) to achieve foot balance and avoid foot deformity. The inapposite insole orthosis was thought to be one of the risk factors of reamputation for foot valgus patient, but biomechanical effects of internal tissues on valgus foot had not been clearly addressed. In this study, plantar pressure on heel and metatarsal regions of PFA was measured using F-Scan. The three-dimensional finite element (FE) model of partial foot evaluated different medial wedge angles (MWAs) (0.0°-10.0°) of orthopedic insole on valgus foot. The effect of orthopedic insole on the internal bone stress, the medial ligament tension of ankle, plantar fascia tension, and plantar pressure was investigated. Plantar pressure on medial heel region was about 2.5 times higher than that of lateral region based on the F-Scan measurements. FE-predicted results showed that the tension of medial ankle ligaments was the lowest, and the plantar pressure was redistributed around the heel, the first metatarsal, and the lateral longitudinal arch regions when MWA of orthopedic insole ranged from 7.5° to 8.0°. The plantar fascias maintained about 3.5% of the total load bearing on foot. However, the internal stresses from foot bones increased. The simulation in this study would provide the suggestion of guiding optimal design of orthopedic insole and therapeutic planning to pedorthist.

Instrument for stable high temperature Seebeck coefficient and resistivity measurements under controlled oxygen partial pressure

DOE PAGES

Ihlefeld, Jon F.; Brown-Shaklee, Harlan James; Sharma, Peter Anand

2015-04-28

The transport properties of ceramic materials strongly depend on oxygen activity, which is tuned by changing the partial oxygen pressure (pO 2) prior to and during measurement. Within, we describe an instrument for highly stable measurements of Seebeck coefficient and electrical resistivity at temperatures up to 1300 K with controlled oxygen partial pressure. An all platinum construction is used to avoid potential materials instabilities that can cause measurement drift. Two independent heaters are employed to establish a small temperature gradient for Seebeck measurements, while keeping the average temperature constant and avoiding errors associated with pO 2-induced drifts in thermocouple readings.more » Oxygen equilibrium is monitored using both an O 2 sensor and the transient behavior of the resistance as a proxy. A pO 2 range of 10 -25–10 0 atm can be established with appropriate gas mixtures. Seebeck measurements were calibrated against a high purity platinum wire, Pt/Pt–Rh thermocouple wire, and a Bi 2Te3 Seebeck coefficient Standard Reference Material. To demonstrate the utility of this instrument for oxide materials we present measurements as a function of pO 2 on a 1 % Nb-doped SrTiO 3 single crystal, and show systematic changes in properties consistent with oxygen vacancy defect chemistry. Thus, an approximately 11% increase in power factor over a pO 2 range of 10 -19–10 -8 atm at 973 K for the donor-doped single crystals is observed.« less

Photosynthetic responses to altitude: an explanation based on optimality principles

NASA Astrophysics Data System (ADS)

Wang, Han; Prenticce, Iain Colin; Davis, Tyler; Keenan, Trevor; Wright, Ian; Peng, Changhui

2017-04-01

Increasing altitude is commonly accompanied by a declining ratio of leaf-internal to ambient CO2 partial pressures (ci:ca; hereafter, χ) and an increase in carboxylation capacity (Vcmax), while carbon assimilation (A) shows little to no change. Here we provide a consistent, quantitative explanation for these responses based on the 'least-cost hypothesis' for the regulation of χ and the 'co-ordination hypothesis' for the regulation of Vcmax. With leaf temperature held constant, our analysis predicts that the cost of maintaining water transport capacity increases with altitude (due to declining atmospheric pressure and increasing vapour pressure deficit, VPD) while the cost of maintaining carboxylation capacity decreases (due to the enhanced affinity of Rubisco for CO2 at low O2 partial pressures). Both effects favour investment in carboxylation capacity rather than water transport capacity. The response of A then reflects the competing effects of stronger CO2 limitation at low ci versus increased radiation penetration through a thinner atmosphere. These effects of atmospheric pressure are expected to be most strongly expressed in herbaceous plants that can maintain leaf temperatures in a narrow range. In leaves closely coupled to the atmosphere additional effects of declining temperature on photosynthesis are expected to modify but not obliterate those of pressure.

Mass Flux of ZnSe by Physical Vapor Transport

NASA Technical Reports Server (NTRS)

Sha, Yi-Gao; Su, Ching-Hua; Palosz, W.; Volz, M. P.; Gillies, D. C.; Szofran, F. R.; Lehoczky, S. L.; Liu, Hao-Chieh; Brebrick, R. F.

1995-01-01

Mass fluxes of ZnSe by physical vapor transport (PVT) were measured in the temperature range of 1050 to 1160 C using an in-situ dynamic technique. The starting materials were either baked out or distilled under vacuum to obtain near-congruently subliming compositions. Using an optical absorption technique Zn and Se, were found to be the dominant vapor species. Partial pressures of Zn and Se, over the starting materials at temperatures between 960 and 1140 C were obtained by measuring the optical densities of the vapor phase at the wavelengths of 2138, 3405, 3508, 3613, and 3792 A. The amount and composition of the residual gas inside the experimental ampoules were measured after the run using a total pressure gauge. For the first time, the experimentally determined partial pressures of Zn and Se, and the amount and composition of the residual gas were used in a one-dimensional diffusion limited analysis of the mass transport rates for a PVT system. Reasonable agreement between the experimental and theoretical results was observed.

Influence of N2 partial pressure on structural and microhardness properties of TiN/ZrN multilayers deposited by Ar/N2 vacuum arc discharge

NASA Astrophysics Data System (ADS)

Naddaf, M.; Abdallah, B.; Ahmad, M.; A-Kharroub, M.

2016-08-01

The influence of N2 partial pressure on structural, mechanical and wetting properties of multilayered TiN/ZrN thin films deposited on silicon substrates by vacuum arc discharge of (N2 + Ar) gas mixtures is investigated. X-ray diffraction (XRD) results show that the average texturing coefficient of (1 1 1) orientation and the grain size of both TiN and ZrN individual layers increase with increasing the N2 partial pressure. The Rutherford back scattering (RBS) measurements and analysis reveal that incorporation of the nitrogen in the film increases with increasing the N2 partial pressure and both TiN and ZrN individual layers have a nitrogen over-stoichiometry for N2 partial pressure ⩾50%. The change in the film micro-hardness is correlated to the changes in crystallographic texture, grain size, stoichiometry and the residual stress in the film as a function of the N2 partial pressure. In particular, stoichiometry of ZrN and TiN individual is found to play the vital role in determining the multilayer hardness. The multilayer film deposited at N2 partial pressure of 25% has the best stoichiometric ratio of both TiN and ZrN layers and the highest micro-hardness of about 32 GPa. In addition, water contact angle (WCA) measurements and analysis show a decrease in the work of adhesion on increasing the N2 partial pressure.

Irradiated ignition of solid materials in reduced pressure atmosphere with various oxygen concentrations for fire safety in space habitats

NASA Astrophysics Data System (ADS)

Nakamura, Y.; Aoki, A.

Effects of sub-atmospheric ambient pressure and oxygen content on irradiated ignition characteristics of solid combustibles were examined experimentally in order to elucidate the flammability and chance of fire in depressurized systems and give ideas for the fire safety and fire fighting strategies for such environments. Thin cellulosic paper was used as the solid combustible since cellulose is one of major organic compounds and flammables in the nature. Applied atmospheres consisted of inert gases (either CO 2 or N 2) and oxygen at various mixture ratios. Total ambient pressure ( P) was varied from 101 kPa (standard atmospheric pressure, P0) to 20 kPa. Ignition was initiated by external thermal radiation with CO 2 laser (10 W total; 21.3 W/cm 2 of the corresponding peak flux) onto the solid surface. Thermal degradation of the solid produced combustible gaseous products (e.g. CO, H 2, or other low weight of HCs) and these products mixed with ambient oxygen to form the combustible mixture over the solid. Heat transfer from the irradiated surface into the mixture accelerated the exothermic reaction in the gas phase and finally thermal runaway (ignition) was achieved. A digital video camera was used to analyze the ignition characteristics. Flammability maps in partial pressure of oxygen (ppO 2) and normalized ambient pressure ( P/ P0) plane were made to reveal the fire hazard in depressurized environments. Results showed that a wider flammable range was obtained in sub-atmospherics conditions. In middle pressure range (101-40 kPa), the required ppO 2 for ignition decreased almost linearly as the total pressure decreased, indicating that higher fire risk is expected. In lower pressure range (<40 kPa), the required partial pressure of oxygen increased dramatically, then ignition was eventually not achieved at pressures less than 20 kPa under the conditions studied here. The findings suggest that it might be difficult to satisfy safety in space agriculture since it has been reported that higher oxygen concentrations are preferable for plant growth in depressurized environments. Our results imply that there is an optimum pressure level to achieve less fire chance with acceptable plant growth. An increase of the flammable range in middle pressure level might be explained by following two effects: one is a physical effect, such as a weak convective thermal removal from ignitable domain (near the hot surface) to the ambient of atmosphere, and the other is chemical effect which causes so-called "explosion peninsula" as a result of depleting radical consumption due to third-body recombination reaction. Further studies are necessary to determine the controlling factor on the observed flammable trend in depressurized conditions.

Coal liquefaction process

DOEpatents

Carr, Norman L.; Moon, William G.; Prudich, Michael E.

1983-01-01

A C.sub.5 -900.degree. F. (C.sub.5 -482.degree. C.) liquid yield greater than 50 weight percent MAF feed coal is obtained in a coal liquefaction process wherein a selected combination of higher hydrogen partial pressure, longer slurry residence time and increased recycle ash content of the feed slurry are controlled within defined ranges.

Toward Martian agriculture: responses of plants to hypobaria

NASA Technical Reports Server (NTRS)

Corey, Kenneth A.; Barta, Daniel J.; Wheeler, Raymond M.

2002-01-01

The recent surge of interest in human missions to Mars has also generated considerable interest in the responses of plants to hypobaria (reduced atmospheric pressure), particularly among those in the advanced life support community. Potential for in situ resource utilization, challenges in meeting engineering constraints for mass and energy, the prospect of using lightweight plant growth structures on Mars, and the minimal literature on plant responses to low pressure all suggest much needed research in this area. However, the limited literature on hypobaria combined with previous findings on plant responses to atmospheric composition and established principles of mass transfer of gases suggest that some plants will be capable of tolerating and growing at pressures below 20 kPa; and for other species, perhaps as low as 5-10 kPa. In addition, normal and perhaps enhanced growth of many plants will likely occur at reduced partial pressures of oxygen (e.g., 5 kPa). Growth of plants at such low and partial pressures indicates the feasibility of cultivating plants in lightweight, transparent "greenhouses" on the surface of Mars or in other extraterrestrial or extreme environment locations. There are numerous, accessible terrestrial analogs for moderately low pressure ranges, but not for very low and extremely low atmospheric pressures. Research pertaining to very low pressures has been historically restricted to the use of vacuum chambers. Future research prospects, approaches, and priorities for plant growth experiments at low pressure are considered and discussed as they apply to prospects for Martian agriculture.

Comparison of 2 cuff inflation methods of laryngeal mask airway Classic for safe use without cuff manometer in adults.

PubMed

Kim, Min-Soo; Lee, Jeong-Rim; Shin, Yang-Sik; Chung, Ji-Won; Lee, Kyu-Ho; Ahn, Ki Ryang

2014-03-01

This single-center, prospective, randomized, double-blind, 2-arm, parallel group comparison trial was performed to establish whether the adult-sized laryngeal mask airway (LMA) Classic (The Laryngeal Mask Company Ltd, Henley-on-Thames, UK) could be used safely without any consideration of cuff hyperinflation when a cuff of the LMA Classic was inflated using half the maximum inflation volume or the resting volume before insertion of device. Eighty patients aged 20 to 70 years scheduled for general anesthesia using the LMA Classic were included. Before insertion, the cuff was partially filled with half the maximum inflation volume in the half volume group or the resting volume created by opening the pilot balloon valve to equalize with atmospheric pressure in the resting volume group. Several parameters regarding insertion, intracuff pressure, airway leak pressure, and leakage volume/fraction were collected after LMA insertion. The LMA Classic with a partially inflated cuff was successfully inserted in all enrolled patients. Both groups had the same success rate of 95% at the first insertion attempt. The half volume group had a lower mean intracuff pressure compared with the resting volume group (54.5 ± 16.1 cm H2O vs 61.8 ± 16.1 cm H2O; P = .047). There was no difference in airway leak pressure or leakage volume/fraction between the 2 groups under mechanical ventilation. The partially inflated cuff method using half the maximum recommended inflation volume or the resting volume is feasible with the adult-sized LMA Classic, resulting in a high success rate of insertion and adequate range of intracuff pressures. Copyright © 2014 Elsevier Inc. All rights reserved.

Sensor for Measuring Hydrogen Partial Pressure in Parabolic Trough Power Plant Expansion Tanks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glatzmaier, Greg C.; Cooney, Daniel A.

The National Renewable Energy Laboratory and Acciona Energy North America are working together to design and implement a process system that provides a permanent solution to the issue of hydrogen buildup at parabolic trough power plants. We are pursuing a method that selectively removes hydrogen from the expansion tanks that serve as reservoirs for the heat transfer fluid (HTF) that circulates in the collector field and power block components. Our modeling shows that removing hydrogen from the expansion tanks at a design rate reduces and maintains dissolved hydrogen in the circulating HTF to a selected target level. Our collaborative workmore » consists of several tasks that are needed to advance this process concept to a development stage, where it is ready for implementation at a commercial power plant. Our main effort is to design and evaluate likely process-unit operations that remove hydrogen from the expansion tanks at a specified rate. Additionally, we designed and demonstrated a method and instrumentation to measure hydrogen partial pressure and concentration in the expansion-tank headspace gas. We measured hydrogen partial pressure in the headspace gas mixture using a palladium-alloy membrane, which is permeable exclusively to hydrogen. The membrane establishes a pure hydrogen gas phase that is in equilibrium with the hydrogen in the gas mixture. We designed and fabricated instrumentation, and demonstrated its effectiveness in measuring hydrogen partial pressures over a range of three orders of magnitude. Our goal is to install this instrument at the Nevada Solar One power plant and to demonstrate its effectiveness in measuring hydrogen levels in the expansion tanks under normal plant operating conditions.« less

Three-step labyrinth seal for high-performance turbomachines

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.

1987-01-01

A three-step labyrinth seal with 12, 11, and 10 labyrinth teeth per step, respectively, was tested under static (nonrotating) conditions. The configuration represented the seal for a high-performance turbopump (e.g., the space shuttle main engine fuel pump). The test data included critical mass flux and pressure profiles over a wide range of fluid conditions at concentric, partially eccentric, and fully eccentric seal positions. The seal mass fluxes (leakage rates) were lower over the entire range of fluid conditions tested than those for data collected for similar straight and three-step cylindrical seals, and this conformed somewhat to expectations. However, the pressure profiles for the eccentric positions indicated little, if any, direct stiffness for this configuration in contrast to significant direct stiffness reported for the straight and three-step cylindrical seals over the range of test conditions. Seal dynamics depend on geometric configuration, inlet and exit parameters, fluid phase, and rotation. The method of corresponding states was applied to the mass flux data, which were found to have a pressure dependency for helium.

On the Experimental and Theoretical Investigations of Lean Partially Premixed Combustion, Burning Speed, Flame Instability and Plasma Formation of Alternative Fuels at High Temperatures and Pressures

NASA Astrophysics Data System (ADS)

Askari, Omid

This dissertation investigates the combustion and injection fundamental characteristics of different alternative fuels both experimentally and theoretically. The subjects such as lean partially premixed combustion of methane/hydrogen/air/diluent, methane high pressure direct-injection, thermal plasma formation, thermodynamic properties of hydrocarbon/air mixtures at high temperatures, laminar flames and flame morphology of synthetic gas (syngas) and Gas-to-Liquid (GTL) fuels were extensively studied in this work. These subjects will be summarized in three following paragraphs. The fundamentals of spray and partially premixed combustion characteristics of directly injected methane in a constant volume combustion chamber have been experimentally studied. The injected fuel jet generates turbulence in the vessel and forms a turbulent heterogeneous fuel-air mixture in the vessel, similar to that in a Compressed Natural Gas (CNG) Direct-Injection (DI) engines. The effect of different characteristics parameters such as spark delay time, stratification ratio, turbulence intensity, fuel injection pressure, chamber pressure, chamber temperature, Exhaust Gas recirculation (EGR) addition, hydrogen addition and equivalence ratio on flame propagation and emission concentrations were analyzed. As a part of this work and for the purpose of control and calibration of high pressure injector, spray development and characteristics including spray tip penetration, spray cone angle and overall equivalence ratio were evaluated under a wide range of fuel injection pressures of 30 to 90 atm and different chamber pressures of 1 to 5 atm. Thermodynamic properties of hydrocarbon/air plasma mixtures at ultra-high temperatures must be precisely calculated due to important influence on the flame kernel formation and propagation in combusting flows and spark discharge applications. A new algorithm based on the statistical thermodynamics was developed to calculate the ultra-high temperature plasma composition and thermodynamic properties. The method was applied to compute the thermodynamic properties of hydrogen/air and methane/air plasma mixtures for a wide range of temperatures (1,000-100,000 K), pressures (10-6-100 atm) and different equivalence ratios within flammability limit. In calculating the individual thermodynamic properties of the atomic species, the Debye-Huckel cutoff criterion has been used for terminating the series expression of the electronic partition function. A new differential-based multi-shell model was developed in conjunction with Schlieren photography to measure laminar burning speed and to study the flame instabilities for different alternative fuels such as syngas and GTL. Flame instabilities such as cracking and wrinkling were observed during flame propagation and discussed in terms of the hydrodynamic and thermo-diffusive effects. Laminar burning speeds were measured using pressure rise data during flame propagation and power law correlations were developed over a wide range of temperatures, pressures and equivalence ratios. As a part of this work, the effect of EGR addition and substitution of nitrogen with helium in air on flame morphology and laminar burning speed were extensively investigated. The effect of cell formation on flame surface area of syngas fuel in terms of a newly defined parameter called cellularity factor was also evaluated. In addition to that the experimental onset of auto-ignition and theoretical ignition delay times of premixed GTL/air mixture were determined at high pressures and low temperatures over a wide range of equivalence ratios.

Effects of Chamber Pressure and Partial Pressure of Water Vapor on Secondary Drying in Lyophilization.

PubMed

Searles, James A; Aravapalli, Sridhar; Hodge, Cody

2017-10-01

Secondary drying is the final step of lyophilization before stoppering, during which water is desorbed from the product to yield the final moisture content. We studied how chamber pressure and partial pressure of water vapor during this step affected the time course of water content of aqueous solutions of polyvinylpyrrolidone (PVP) in glass vials. The total chamber pressure had no effect when the partial pressure of water vapor was very low. However, when the vapor phase contained a substantial fraction of water vapor, the PVP moisture content was much higher. We carried out dynamic vapor sorption experiments (DVS) to demonstrate that the higher PVP moisture content was a straightforward result of the higher water vapor content in the lyophilizer. The results highlight that the partial pressure of water vapor is extremely important during secondary drying in lyophilization, and that lower chamber pressure set points for secondary drying may sometimes be justified as a strategy for ensuring low partial pressure of water vapor, especially for lyophilizers that do not inject dry gas to control pressure. These findings have direct application for process transfers/scale ups from freeze-dryers that do not inject dry gas for pressure control to those that do, and vice versa.

Applying Chemical Potential and Partial Pressure Concepts to Understand the Spontaneous Mixing of Helium and Air in a Helium-Inflated Balloon

ERIC Educational Resources Information Center

Jee-Yon Lee; Hee-Soo Yoo; Jong Sook Park; Kwang-Jin Hwang; Jin Seog Kim

2005-01-01

The spontaneous mixing of helium and air in a helium-inflated balloon is described in an experiment in which the partial pressure of the gases in the balloon are determined from the mole factions and the total pressure measured in the balloon. The results described provide a model for teaching concepts of partial pressure, chemical potential, and…

In-reactor oxidation of zircaloy-4 under low water vapor pressures

NASA Astrophysics Data System (ADS)

Luscher, Walter G.; Senor, David J.; Clayton, Kevin K.; Longhurst, Glen R.

2015-01-01

Complementary in- and ex-reactor oxidation tests have been performed to evaluate the oxidation and hydrogen absorption performance of Zircaloy-4 (Zr-4) under relatively low partial pressures (300 and 1000 Pa) of water vapor at specified test temperatures (330 and 370 °C). Data from these tests will be used to support the fabrication of components intended for isotope-producing targets and provide information regarding the temperature and pressure dependence of oxidation and hydrogen absorption of Zr-4 over the specified range of test conditions. Comparisons between in- and ex-reactor test results were performed to evaluate the influence of irradiation.

Combined hydraulic and regenerative braking system

DOEpatents

Venkataperumal, R.R.; Mericle, G.E.

1979-08-09

A combined hydraulic and regenerative braking system and method for an electric vehicle is disclosed. The braking system is responsive to the applied hydraulic pressure in a brake line to control the braking of the vehicle to be completely hydraulic up to a first level of brake line pressure, to be partially hydraulic at a constant braking force and partially regenerative at a linearly increasing braking force from the first level of applied brake line pressure to a higher second level of brake line pressure, to be partially hydraulic at a linearly increasing braking force and partially regenerative at a linearly decreasing braking force from the second level of applied line pressure to a third and higher level of applied line pressure, and to be completely hydraulic at a linearly increasing braking force from the third level to all higher applied levels of line pressure.

Combined hydraulic and regenerative braking system

DOEpatents

Venkataperumal, Rama R.; Mericle, Gerald E.

1981-06-02

A combined hydraulic and regenerative braking system and method for an electric vehicle, with the braking system being responsive to the applied hydraulic pressure in a brake line to control the braking of the vehicle to be completely hydraulic up to a first level of brake line pressure, to be partially hydraulic at a constant braking force and partially regenerative at a linearly increasing braking force from the first level of applied brake line pressure to a higher second level of brake line pressure, to be partially hydraulic at a linearly increasing braking force and partially regenerative at a linearly decreasing braking force from the second level of applied line pressure to a third and higher level of applied line pressure, and to be completely hydraulic at a linearly increasing braking force from the third level to all higher applied levels of line pressure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Pei; Fang, Z. Zak; Koopman, Mark

Hydrogen has been investigated for decades as a temporary alloying element to refine the microstructure of Ti-6Al-4V, and is now being used in a novel powder metallurgy method known as "hydrogen sintering and phase transformation". Pseudo-binary phase diagrams of (Ti-6Al-4V)-xH have been studied and developed, but are not well established due to methodological limitations. In this paper, in situ studies of phase transformations during hydrogenation and dehydrogenation of (Ti-6Al-4V)-xH alloys were conducted using high-energy synchrotron X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The eutectoid phase transformation of β ↔ α + δ was observed in themore » (Ti-6Al-4V)-xH alloy via in situ synchrotron XRD at 211 °C with a hydrogen concentration of 37.5 at.% (measured using TGA-DSC). The relationships of hydrogen composition to partial pressure and temperature were investigated in the temperature range 450-900°C. Based on these results, a partial pseudo-binary phase diagram of (Ti-6Al-4V)-xH is proposed for hydrogen compositions up to 60 at.% in the temperature range 100-900°C. Using the data collected in real time under controlled parameters of temperature, composition and hydrogen partial pressure, this work characterizes relevant phase transformations and microstructural evolution for practical titanium-hydrogen technologies of Ti-6Al-4V.« less

When immiscible becomes miscible-Methane in water at high pressures.

PubMed

Pruteanu, Ciprian G; Ackland, Graeme J; Poon, Wilson C K; Loveday, John S

2017-08-01

At low pressures, the solubility of gases in liquids is governed by Henry's law, which states that the saturated solubility of a gas in a liquid is proportional to the partial pressure of the gas. As the pressure increases, most gases depart from this ideal behavior in a sublinear fashion, leveling off at pressures in the 1- to 5-kbar (0.1 to 0.5 GPa) range with solubilities of less than 1 mole percent (mol %). This contrasts strikingly with the well-known marked increase in solubility of simple gases in water at high temperature associated with the critical point (647 K and 212 bar). The solubility of the smallest hydrocarbon, the simple gas methane, in water under a range of pressure and temperature is of widespread importance, because it is a paradigmatic hydrophobe and occurs widely in terrestrial and extraterrestrial geology. We report measurements up to 3.5 GPa of the pressure dependence of the solubility of methane in water at 100°C-well below the latter's critical temperature. Our results reveal a marked increase in solubility between 1 and 2 GPa, leading to a state above 2 GPa where the maximum solubility of methane in water exceeds 35 mol %.

Simulation of gas bubbles in hypobaric decompressions: roles of O2, CO2, and H2O.

PubMed

Van Liew, H D; Burkard, M E

1995-01-01

To gain insight into the special features of bubbles that may form in aviators and astronauts, we simulated the growth and decay of bubbles in two hypobaric decompressions and a hyperbaric one, all with the same tissue ratio (TR), where TR is defined as tissue PN2 before decompression divided by barometric pressure after. We used an equation system which is solved by numerical methods and accounts for simultaneous diffusion of any number of gases as well as other major determinants of bubble growth and absorption. We also considered two extremes of the number of bubbles which form per unit of tissue. A) Because physiological mechanisms keep the partial pressures of the "metabolic" gases (O2, CO2, and H2O) nearly constant over a range of hypobaric pressures, their fractions in bubbles are inversely proportional to pressure and their large volumes at low pressure add to bubble size. B) In addition, the large fractions facilitate the entry of N2 into bubbles, and when bubble density is low, enhance an autocatalytic feedback on bubble growth due to increasing surface area. C) The TR is not closely related to bubble size; that is when two different decompressions have the same TR, metabolic gases cause bubbles to grow larger at lower hypobaric pressures. We conclude that the constancy of partial pressures of metabolic gases, unimportant in hyperbaric decompressions, affects bubble size in hypobaric decompressions in inverse relation to the exposure pressure.

Hydrogen Permeability of Incoloy 800H, Inconel 617, and Haynes 230 Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pattrick Calderoni

A potential issue in the design of the NGNP reactor and high-temperature components is the permeation of fission generated tritium and hydrogen product from downstream hydrogen generation through high-temperature components. Such permeation can result in the loss of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system. The issue will be addressed in the engineering design phase, and requires knowledge of permeation characteristics of the candidate alloys. Of three potential candidates for high-temperature components of the NGNP reactor design, the hydrogen permeability has been documented well onlymore » for Incoloy 800H, but at relatively high partial pressures of hydrogen. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. The hydrogen permeability of Haynes 230 has not been published. To support engineering design of the NGNP reactor components, the hydrogen permeability of Inconel 617 and Haynes 230 were determined using a measurement system designed and fabricated at the Idaho National Laboratory. The performance of the system was validated using Incoloy 800H as reference material, for which the permeability has been published in several journal articles. The permeability of Incoloy 800H, Inconel 617 and Haynes 230 was measured in the temperature range 650 to 950 °C and at hydrogen partial pressures of 10-3 and 10-2 atm, substantially lower pressures than used in the published reports. The measured hydrogen permeability of Incoloy 800H and Inconel 617 were in good agreement with published values obtained at higher partial pressures of hydrogen. The hydrogen permeability of Inconel 617 and Haynes 230 were similar, about 50% greater than for Incoloy 800H and with similar temperature dependence.« less

Measurement and interpretation of the oxygen isotope composition of carbon dioxide respired by leaves in the dark.

PubMed

Cernusak, Lucas A; Farquhar, Graham D; Wong, S Chin; Stuart-Williams, Hilary

2004-10-01

We measured the oxygen isotope composition (delta(18)O) of CO(2) respired by Ricinus communis leaves in the dark. Experiments were conducted at low CO(2) partial pressure and at normal atmospheric CO(2) partial pressure. Across both experiments, the delta(18)O of dark-respired CO(2) (delta(R)) ranged from 44 per thousand to 324 per thousand (Vienna Standard Mean Ocean Water scale). This seemingly implausible range of values reflects the large flux of CO(2) that diffuses into leaves, equilibrates with leaf water via the catalytic activity of carbonic anhydrase, then diffuses out of the leaf, leaving the net CO(2) efflux rate unaltered. The impact of this process on delta(R) is modulated by the delta(18)O difference between CO(2) inside the leaf and in the air, and by variation in the CO(2) partial pressure inside the leaf relative to that in the air. We developed theoretical equations to calculate delta(18)O of CO(2) in leaf chloroplasts (delta(c)), the assumed location of carbonic anhydrase activity, during dark respiration. Their application led to sensible estimates of delta(c), suggesting that the theory adequately accounted for the labeling of CO(2) by leaf water in excess of that expected from the net CO(2) efflux. The delta(c) values were strongly correlated with delta(18)O of water at the evaporative sites within leaves. We estimated that approximately 80% of CO(2) in chloroplasts had completely exchanged oxygen atoms with chloroplast water during dark respiration, whereas approximately 100% had exchanged during photosynthesis. Incorporation of the delta(18)O of leaf dark respiration into ecosystem and global scale models of C(18)OO dynamics could affect model outputs and their interpretation.

[Evaluation of super dwarf wheat growth and development in greenhouse "Svet" during cultivation in inhabited pressurized chamber

NASA Technical Reports Server (NTRS)

Sychev, V. N.; Levinskikh, M. A.; Podol'skii, I. G.; Ivanova, I. E.; Nefedova, E. L.; Livanskaia, O. G.; Derendiaeva, T. A.; Mikhailov, N. I.; Salisbury, F. B.; Bingham, G. E.;

Characteristics of a Sealed Internally Balanced Aileron from Tests of a 1/4-Scale Partial-Span Model of the Republic XF-12 Airplane in the Langley 19-Foot Pressure Tunnel

NASA Technical Reports Server (NTRS)

Graham, Robert R.; Martina, Albert P.; Salmi, Reino J.

1946-01-01

This paper presents the results of the aileron investigation and includes rolling-moment, yawing-moment, and aileron hinge-moment coefficients and pressure coefficients across the aileron-balance seal through a range of angle of attack, tab deflection, and aileron deflection with flaps neutral and deflected 20 degrees and 55 degrees. Some of the effects of wing roughness and balance seal leakage on the aileron and tab characteristics are also presented.

Structural, mechanical, electrical and wetting properties of ZrNx films deposited by Ar/N2 vacuum arc discharge: Effect of nitrogen partial pressure

NASA Astrophysics Data System (ADS)

Abdallah, B.; Naddaf, M.; A-Kharroub, M.

2013-03-01

Non-stiochiometric zirconium nitride (ZrNx) thin films have been deposited on silicon substrates by vacuum arc discharge of (N2 + Ar) gas mixtures at different N2 partial pressure ratio. The microstructure, mechanical, electrical and wetting properties of these films are studied by means of X-ray diffraction (XRD), micro-Raman spectroscopy, Rutherford back scattering (RBS) technique, conventional micro-hardness testing, electrical resistivity, atomic force microscopy (AFM) and contact angle (CA) measurements. RBS results and analysis show that the (N/Zr) ratio in the film increases with increasing the N2 partial pressure. A ZrNx film with (Zr/N) ratio in the vicinity of stoichiometric ZrN is obtained at N2 partial pressure of 10%. XRD and Raman results indicate that all deposited films have strained cubic crystal phase of ZrN, regardless of the N2 partial pressure. On increasing the N2 partial pressure, the relative intensity of (1 1 1) orientation with respect to (2 0 0) orientation is seen to decrease. The effect of N2 partial pressure on micro-hardness and the resistivity of the deposited film is revealed and correlated to the alteration of grain size, crystallographic texture, stoichiometry and residual stress developed in the film. In particular, it is found that residual stress and nitrogen incorporation in the film play crucial role in the alteration of micro-hardness and resistivity respectively. In addition, CA and AFM results demonstrate that as N2 partial pressure increases, both the surface hydrophobicity and roughness of the deposited film increase, leading to a significant decrease in the film surface free energy (SFE).

Sulfur control in ion-conducting membrane systems

DOEpatents

Stein, VanEric Edward; Richards, Robin Edward; Brengel, David Douglas; Carolan, Michael Francis

2003-08-05

A method for controlling the sulfur dioxide partial pressure in a pressurized, heated, oxygen-containing gas mixture which is contacted with an ion-conducting metallic oxide membrane which permeates oxygen ions. The sulfur dioxide partial pressure in the oxygen-depleted non-permeate gas from the membrane module is maintained below a critical sulfur dioxide partial pressure, p.sub.SO2 *, to protect the membrane material from reacting with sulfur dioxide and reducing the oxygen flux of the membrane. Each ion-conducting metallic oxide material has a characteristic critical sulfur dioxide partial pressure which is useful in determining the required level of sulfur removal from the feed gas and/or from the fuel gas used in a direct-fired feed gas heater.

Shoot dieback during prolonged drought in Ceanothus (Rhamnaceae) chaparral of California: a possible case of hydraulic failure.

PubMed

Davis, Stephen D; Ewers, Frank W; Sperry, John S; Portwood, Kimberly A; Crocker, Michelle C; Adams, Gerard C

2002-05-01

Progressive diebacks of outer canopy branchlets of Ceanothus crassifolius were repeatedly observed after rainless periods up to 9 mo in duration in the Santa Monica Mountains of southern California. Mean xylem pressures of branchlets near the end of drought were as low as -11.2 MPa (N = 22) with a mean of about 60 dead branchlets per shrub. Inoculation (N = 15) with three species of fungi previously isolated from the same population of C. crassifolius did not promote dieback, suggesting that the observed decline was not fungal induced, as had been proposed. Further, at least 50% of healthy-appearing twigs, without symptoms of dieback, contained isolatible endophytic fungi. We used a centrifugal force method to determine the range of xylem pressure causing cavitation (vulnerability curves) for branchlets (N = 12) and roots (N = 16). We combined vulnerability curves with soil texture data (N = 6) into a water transport model that estimated the critical values (P(Lcrit)) of leaf xylem pressure associated with the loss of water from soil to foliage. Maximum P(Lcrit) was between -10 and -11 MPa and within the range of minimum measured xylem pressures of branchlets during drought and dieback. Branchlet dieback correlated with seasonal declines in xylem pressure in concert with declining safety margins from hydraulic failure. Symptoms of dieback were duplicated in the field by partially severing stem xylem that normally supplied branchlets with water. Taken together, these results indicate that loss of hydraulic conductance to foliage was the probable cause of the observed dieback in C. crassifolius. Partial dieback of peripheral branchlets, and its attendant reduction in evaporative surface area, may be a last-resort mechanism for whole-plant water conservation and drought survival in this species.

Performance data of the new free-piston shock tunnel at GALCIT

NASA Technical Reports Server (NTRS)

Hornung, Hans G.

1992-01-01

The new free-piston shock tunnel has been partially calibrated, and a range of operating conditions has been found. A large number of difficulties were encountered during the shake-down period, of which the ablation of various parts was the most severe. Solutions to these problems were found. The general principles of high-enthalpy simulation are outlined, and the parameter space covered by T5 is given. Examples of the operating data show that, with care, excellent repeatability may be obtained. The temporal uniformity of the reservoir pressure is very good, even at high enthalpy, because it is possible to operate at tailored-interface and tuned-piston conditions over the whole enthalpy range. Examples of heat transfer and Pitot-pressure measurements are also presented.

Partial discharge detection and analysis in low pressure environments

NASA Astrophysics Data System (ADS)

Liu, Xin

Typical aerospace vehicles (aircraft and spacecraft) experience a wide range of operating pressures during ascending and returning to earth. Compared to the sea-level atmospheric pressure (760 Torr), the pressure at about 60 km altitude is 2 Torr. The performance of the electric power system components of the aerospace vehicles must remain reliable even under such sub-atmospheric operating conditions. It is well known that the dielectric strength of gaseous insulators, while the electrode arrangement remains unchanged, is pressure dependent. Therefore, characterization of the performance and behavior of the electrical insulation in flight vehicles in low-pressure environments is extremely important. Partial discharge testing is one of the practical methods for evaluating the integrity of electrical insulation in aerospace vehicles. This dissertation describes partial discharge (PD) measurements performed mainly with 60 Hz ac energization in air, argon and helium, for pressures between 2 and 760 Torr. Two main electrode arrangements were used. One was a needle-plane electrode arrangement with a Teflon insulating barrier. The other one was a twisted pair of insulated conductors taken from a standard aircraft wiring harness. The measurement results are presented in terms of typical PD current pulse waveforms and waveform analysis for both main electrode arrangements. The evaluation criteria are the waveform polarity, magnitude, shape, rise time, and phase angle (temporal location) relative to the source voltage. Two-variable histograms and statistical averages of the PD parameters are presented. The PD physical mechanisms are analyzed. For PD pattern recognition, both statistical methods (such as discharge parameter dot pattern representation, discharge parameter phase distribution, statistical operator calculations, and PD fingerprint development) and wavelet transform applications are investigated. The main conclusions of the dissertation include: (1) The PD current pulse waveforms are dependent on the pressure. (2) The rise time of the waveform is another effective PD current pulse characteristic indicator. (3) PD fingerprint patterns that are already available for atmospheric pressure (760 Torr) conditions are inadequate for the evaluation of PD pulses at low pressures. (4) Various wavelet transform techniques can be used effectively for PD pulse signal denoising purposes, and for PD pulse waveform transient feature recognition.

Effect of substrate temperature and oxygen partial pressure on RF sputtered NiO thin films

NASA Astrophysics Data System (ADS)

Cheemadan, Saheer; Santhosh Kumar, M. C.

2018-04-01

Nickel oxide (NiO) thin films were deposited by RF sputtering process and the physical properties were investigated for varying substrate temperatures and oxygen partial pressure. The variation of the crystallographic orientation and microstructure of the NiO thin films with an increase in substrate temperature were studied. It was observed that NiO thin films deposited at 350 °C shows relatively good crystalline characteristics with a preferential orientation along (111) plane. With the optimum substrate temperature of 350 °C, the NiO thin films were deposited under various oxygen partial pressures at the same experimental conditions. The structural, optical and electrical properties of NiO thin films under varying oxygen partial pressure of 10%–50% were investigated. From XRD it is clear that the films prepared in the pure argon atmosphere were amorphous while the films in oxygen partial pressure exhibited polycrystalline NiO phase. SEM and AFM investigations unveil that the higher substrate temperature improves the microstructure of the thin films. It is revealed that the NiO thin films deposited at oxygen partial pressure of 40% and a substrate temperature of 350 °C, showed higher electrical conductivity with p-type characteristics.

Partial Pressures for Several In-Se Compositions from Optical Absorbance of the Vapor

NASA Technical Reports Server (NTRS)

Brebrick, R. F.; Su, Ching-Hua

2001-01-01

The optical absorbance of the vapor phase over various In-Se compositions between 33.3-60.99 at.% Se and 673-1418 K was measured and used to obtain the partial pressures of Se2(g) and In2Se(g). The results are in agreement with silica Bourdon gauge measurements for compositions between 50-61 at.%, but significantly higher than those from Knudsen cell and simultaneous Knudsen-torsion cell measurements. It is found that 60.99 at.% Se lies outside the sesquiselenide homogeneity range and 59.98 at.% Se lies inside and is the congruently melting composition. The Gibbs energy of formation of the liquid from its pure liquid elements between 1000-1300 K is essentially independent of temperature and falls between -36 to -38 kJ per g atomic weight for 50 and 56% Se at 1200 and 1300 K.

Hugoniot measurements of double-shocked precompressed dense xenon plasmas

NASA Astrophysics Data System (ADS)

Zheng, J.; Chen, Q. F.; Gu, Y. J.; Chen, Z. Y.

2012-12-01

The current partially ionized plasmas models for xenon show substantial differences since the description of pressure and thermal ionization region becomes a formidable task, prompting the need for an improved understanding of dense xenon plasmas behavior at above 100 GPa. We performed double-shock compression experiments on dense xenon to determine accurately the Hugoniot up to 172 GPa using a time-resolved optical radiation method. The planar strong shock wave was produced using a flyer plate impactor accelerated up to ˜6 km/s with a two-stage light-gas gun. The time-resolved optical radiation histories were acquired by using a multiwavelength channel optical transience radiance pyrometer. Shock velocity was measured and mass velocity was determined by the impedance-matching methods. The experimental equation of state of dense xenon plasmas are compared with the self-consistent fluid variational calculations of dense xenon in the region of partial ionization over a wide range of pressures and temperatures.

Diving under a microscope--a new simple and versatile in vitro diving device for fluorescence and confocal microscopy allowing the controls of hydrostatic pressure, gas pressures, and kinetics of gas saturation.

PubMed

Wang, Qiong; Belhomme, Marc; Guerrero, François; Mazur, Aleksandra; Lambrechts, Kate; Theron, Michaël

2013-06-01

How underwater diving effects the function of the arterial wall and the activities of endothelial cells is the focus of recent studies on decompression sickness. Here we describe an in vitro diving system constructed to achieve real-time monitoring of cell activity during simulated dives under fluorescent microscopy and confocal microscopy. A 1-mL chamber with sapphire windows on both sides and located on the stage of an inverted microscope was built to allow in vitro diving simulation of isolated cells or arteries in which activities during diving are monitored in real-time via fluorescent microscopy and confocal microscopy. Speed of compression and decompression can range from 20 to 2000 kPa/min, allowing systemic pressure to range up to 6500 kPa. Diving temperature is controlled at 37°C. During air dive simulation oxygen partial pressure is optically monitored. Perfusion speed can range from 0.05 to 10 mL/min. The system can support physiological viability of in vitro samples for real-time monitoring of cellular activity during diving. It allows regulations of pressure, speeds of compression and decompression, temperature, gas saturation, and perfusion speed. It will be a valuable tool for hyperbaric research.

Oxygen partial pressure effects on the RF sputtered p-type NiO hydrogen gas sensors

NASA Astrophysics Data System (ADS)

Turgut, Erdal; Çoban, Ömer; Sarıtaş, Sevda; Tüzemen, Sebahattin; Yıldırım, Muhammet; Gür, Emre

2018-03-01

NiO thin films were grown by Radio Frequency (RF) Magnetron Sputtering method under different oxygen partial pressures, which are 0.6 mTorr, 1.3 mTorr and 2.0 mTorr. The effects of oxygen partial pressures on the thin films were analyzed through Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Hall measurements. The change in the surface morphology of the thin films has been observed with the SEM and AFM measurements. While nano-pyramids have been obtained on the thin film grown at the lowest oxygen partial pressure, the spherical granules lower than 60 nm in size has been observed for the samples grown at higher oxygen partial pressures. The shift in the dominant XRD peak is realized to the lower two theta angle with increasing the oxygen partial pressures. XPS measurements showed that the Ni2p peak involves satellite peaks and two oxidation states of Ni, Ni2+ and Ni3+, have been existed together with the corresponding splitting in O1s spectrum. P-type conductivity of the grown NiO thin films are confirmed by the Hall measurements with concentrations on the order of 1013 holes/cm-3. Gas sensor measurements revealed minimum of 10% response to the 10 ppm H2 level. Enhanced responsivity of the gas sensor devices of NiO thin films is shown as the oxygen partial pressure increases.

Distribution of gases in the unsaturated zone at a low-level radioactive-waste disposal site near Sheffield, Illinois

USGS Publications Warehouse

Striegl, Robert G.

1988-01-01

The unsaturated zone is a medium that provides pneumatic communication for the movement of gases from wastes buried in landfills to the atmosphere, biota, and groundwater. Gases in unsaturated glacial and eolian deposits near a waste-disposal trench at the low-level radioactive-waste disposal site near Sheffield, Bureau County, Illinois, were identified, and the spatial and temporal distributions of the partial pressures of those gases were determined for the period January 1984 through January 1986. Methods for the collection and analyses of the gases are described, as are geologic and hydrologic characteristics of the unsaturated zone that affect gas transport. The identified gases, which are of natural and of waste origin, include nitrogen, oxygen, and argon, carbon dioxide, methane, propane, butane, tritiated water vapor, 14carbon dioxide, and 222 radon. Concentrations of methane and 14carbon dioxide originated at the waste, as shown by partial-pressure gradients of the gases; 14carbon dioxide partial pressures exceeded natural background partial pressures by factors greater than 1 million at some locations. Variations in partial pressures of oxygen and carbon dioxide were seasonal among piezometers because of increased root and soil-microbe respiration during summer. Variations in methane and 14carbon dioxide partial pressures were apparently related to discrete releases from waste sources at unpredictable intervals of time. No greater than background partial pressures for tritiated water vapor or 222 radon were measured. (USGS)

[Effects of gap junction blocking on the oxygen partial pressure in acupoints of the bladder meridian].

PubMed

Wang, Qi; Yu, Wei-Chang; Jiang, Hong-Zhi; Chen, Sheng-Li; Zhang, Ming-Min; Kong, E-Sheng; Huang, Guang-Ying

2010-12-01

To explore the relation between gap junction and meridian phenomenon. The oxygen partial pressure in acupoints [see text for formula] and in their corresponding non-acupoints of the Bladder Meridian was observed with the needle-type tissue oxygen tension sensor in the gap junction blocking goats by 1-Heptanol injection and the Connexin 43 (Cx43) gene knockout mice. (1) The oxygen partial pressure in acupoints of Bladder Meridian on goats was higher than that in non-acupoints after 1-Heptanol injection with significant differences between them (both P < 0.01). (2) The oxygen partial pressure in acupoints of Bladder Meridian on goats increased significantly after injecting 1-Heptanol as compare with that either injecting normal saline or injecting nothing with significant differences between them (all P < 0.01). (3) The oxygen partial pressure in acupoints of the Bladder Meridian was significantly higher than that in the non-acupoint controls in Cx43 wild type (WT) mice (all P < 0.01). In Cx43 heterozygote (HT) mice, the oxygen partial pressure between acupoints and non-acupoint controls showed no significant differences (all P > 0.05). (4) In acupoints, the oxygen partial pressure in Cx43 WT mice was significantly higher than that in Cx43 HT mice (all P < 0.05), while in the corresponding non-acupoints, this difference had no statistically significant (all P > 0.05). Gap junction maybe the essential factor in signal transduction of acupuncture.

Surface pressure field mapping using luminescent coatings

NASA Technical Reports Server (NTRS)

Mclachlan, B. G.; Kavandi, J. L.; Callis, J. B.; Gouterman, M.; Green, E.; Khalil, G.; Burns, D.

1993-01-01

In recent experiments we demonstrated the feasibility of using the oxygen dependence of luminescent molecules for surface pressure measurement in aerodynamic testing. This technique is based on the observation that for many luminescent molecules the light emitted increases as the oxygen partial pressure, and thus the air pressure, the molecules see decreases. In practice the surface to be observed is coated with an oxygen permeable polymer containing a luminescent molecule and illuminated with ultraviolet radiation. The airflow induced surface pressure field is seen as a luminescence intensity distribution which can be measured using quantitative video techniques. Computer processing converts the video data into a map of the surface pressure field. The experiments consisted of evaluating a trial luminescent coating in measuring the static surface pressure field over a two-dimensional NACA-0012 section model airfoil for Mach numbers ranging from 0.3 and 0.66. Comparison of the luminescent coating derived pressures were made to those obtained from conventional pressure taps. The method along with the experiment and its results will be described.

Partial Cavity Flows at High Reynolds Numbers

NASA Astrophysics Data System (ADS)

Makiharju, Simo; Elbing, Brian; Wiggins, Andrew; Dowling, David; Perlin, Marc; Ceccio, Steven

2009-11-01

Partial cavity flows created for friction drag reduction were examined on a large-scale. Partial cavities were investigated at Reynolds numbers up to 120 million, and stable cavities with frictional drag reduction of more than 95% were attained at optimal conditions. The model used was a 3 m wide and 12 m long flat plate with a plenum on the bottom. To create the partial cavity, air was injected at the base of an 18 cm backwards-facing step 2.1 m from the leading edge. The geometry at the cavity closure was varied for different flow speeds to optimize the closure of the cavity. Cavity gas flux, thickness, frictional loads, and cavity pressures were measured over a range of flow speeds and air injection fluxes. High-speed video was used extensively to investigate the unsteady three dimensional cavity closure, the overall cavity shape and oscillations.

Intraluminal pressure response in Baerveldt tube shunts: a comparison of modification techniques.

PubMed

Gilbert, David D; Bond, Brent

2007-01-01

To design an apparatus for in vitro quantification of effects of modifications to nonvalved tube shunts, and to compare the effects of these modifications done to prevent early postoperative hypotony. A testing apparatus was designed and constructed to measure intraluminal pressure (ILP) during constant infusion of balanced salt solution at 2 microL/min through Baerveldt tube shunts mounted on cadaver eyes. Three different modifications were performed and 3 shunts were used for each modification. The modifications were partial tube occlusion with a 3-0 Supramid suture, tube perforation with a 27-gauge needle on an occluded tube, and a 1.2 mm longitudinal venting slit on an occluded tube. The final steady state ILP for the 3-0 Supramid partially occluded tube ranged between 1.6 and 2.8 mm Hg over 3 trials with an average final steady state ILP of 2.0 mm Hg. The 27-gauge needle perforation produced ILPs of 4.6 to 8.2 mm Hg over 3 trials with an average final steady state pressure of 5.9 mm Hg. The 1.2 mm longitudinal venting slit produced an ILP range of 12.6 to 17.3 mm Hg over 3 trials with an average final steady state ILP of 14.8 mm Hg. The differences in final steady state ILP between the 3 modification techniques were statistically significant (P=0.00036). The 3-0 Supramid occlusion and the 27-gauge perforation techniques produced hypotony, whereas the 1.2 mm longitudinal venting slit produced acceptable pressures in vitro.

Temperature dependence of partial conductivities of the BaZr0.7Ce0.2Y0.1O3-δ proton conductor

NASA Astrophysics Data System (ADS)

Heras-Juaristi, Gemma; Pérez-Coll, Domingo; Mather, Glenn C.

2017-10-01

Partial conductivities are presented for BaZr0.7Ce0.2Y0.1O3-δ, an important proton conductor for protonic-ceramic fuel cells and membrane reactors. Atmospheric dependencies of impedance performed in humidified and dry O2, air, N2 and H2(10%)/N2(90%) in the temperature range 300-900 °C, supported by the modified emf method, confirm significant electron-hole and protonic contributions to transport. For very reducing and wet atmospheres, the conductivity is predominantly ionic, with a higher participation of protons with decreasing temperature and increasing water-vapour partial pressure (pH2O). From moderately reducing conditions of wet N2 to wet O2, however, the conductivity is considerably influenced by electron holes as revealed by a significant dependence of total conductivity on oxygen partial pressure (pO2). With higher pH2O, proton transport increases, with a concomitant decrease of holes and oxygen vacancies. However, the effect of pH2O is also influenced by temperature, with a greater protonic contribution at both lower temperature and pO2. Values of proton transport number tH ≈ 0.63 and electronic transport number th ≈ 0.37 are obtained at 600 °C for pH2O = 0.022 atm and pO2 = 0.2 atm, whereas tH ≈ 0.95 and th ≈ 0.05 for pO2 = 10-5 atm. A hydration enthalpy of -109 kJ mol-1 is obtained in the range 600-900 °C.

String of turquoise: The future of Sacred Mountain Peaks in the southwest U.S.

Treesearch

Linda Moon Stumpff

2011-01-01

The Southwest is the birthplace of wilderness policy in the United States, yet the unique ecological environments of its peaks, cordilleras, and ranges that dot the high desert remain only partially protected. Some areas are relatively secure, yet midcentury Federal policy responded to multiple development pressures, from ski basins to roads, that sliced these peaks...

Biomechanical analysis of articular-sided partial-thickness rotator cuff tear and repair.

PubMed

Mihata, Teruhisa; McGarry, Michelle H; Ishihara, Yoko; Bui, Christopher N H; Alavekios, Damon; Neo, Masashi; Lee, Thay Q

2015-02-01

Articular-sided partial-thickness rotator cuff tears are common injuries in throwing athletes. The superior shoulder capsule beneath the supraspinatus and infraspinatus tendons works as a stabilizer of the glenohumeral joint. To assess the effect of articular-sided partial-thickness rotator cuff tear and repair on shoulder biomechanics. The hypothesis was that shoulder laxity might be changed because of superior capsular plication in transtendon repair of articular-sided partial-thickness rotator cuff tears. Controlled laboratory study. Nine fresh-frozen cadaveric shoulders were tested by using a custom shoulder-testing system at the simulated late-cocking phase and acceleration phase of throwing motion. Maximum glenohumeral external rotation angle, anterior translation, position of the humeral head apex with respect to the glenoid, internal impingement area, and glenohumeral and subacromial contact pressures were measured. Each specimen underwent 3 stages of testing: stage 1, with the intact shoulder; stage 2, after creation of articular-sided partial-thickness tears of the supraspinatus and infraspinatus tendons; and stage 3, after transtendon repair of the torn tendons by using 2 suture anchors. Articular-sided partial-thickness tears did not significantly change any of the shoulder biomechanical measurements. In the simulated late-cocking phase, transtendon rotator cuff repair resulted in decreased maximum external rotation angle by 4.2° (P = .03), posterior shift of the humeral head (1.1-mm shift; P = .02), decreased glenohumeral contact pressure by 1.7 MPa (56%; P = .004), and decreased internal impingement area by 26.4 mm(2) (65%; P < .001) compared with values in the torn shoulder. In the acceleration phase, the humeral head shifted inferiorly (1.2-mm shift; P = .03 vs torn shoulder), and glenohumeral anterior translation (1.5-mm decrease; P = .03 vs torn shoulder) and subacromial contact pressure (32% decrease; P = .004 vs intact shoulder) decreased significantly after transtendon repair. Transtendon repair of articular-sided partial-thickness supraspinatus and infraspinatus tears decreased glenohumeral and subacromial contact pressures at time zero; these changes might lead to reduced secondary subacromial and internal impingements and consequently progression to full-thickness rotator cuff tear. However, repair of the tendons decreased anterior translation and external rotation and changed the positional relationship between the humeral head and the glenoid. Careful attention should be paid to shoulder laxity and range of motion when transtendon repair is chosen to treat articular-sided partial-thickness rotator cuff tears, specifically in throwing athletes. © 2014 The Author(s).

The inference of atmospheric ozone using satellite horizon measurements in the 1042 per cm band.

NASA Technical Reports Server (NTRS)

Russell, J. M., III; Drayson, S. R.

1972-01-01

Description of a method for inferring atmospheric ozone information using infrared horizon radiance measurements in the 1042 per cm band. An analysis based on this method proves the feasibility of the horizon experiment for determining ozone information and shows that the ozone partial pressure can be determined in the altitude range from 50 down to 25 km. A comprehensive error study is conducted which considers effects of individual errors as well as the effect of all error sources acting simultaneously. The results show that in the absence of a temperature profile bias error, it should be possible to determine the ozone partial pressure to within an rms value of 15 to 20%. It may be possible to reduce this rms error to 5% by smoothing the solution profile. These results would be seriously degraded by an atmospheric temperature bias error of only 3 K; thus, great care should be taken to minimize this source of error in an experiment. It is probable, in view of recent technological developments, that these errors will be much smaller in future flight experiments and the altitude range will widen to include from about 60 km down to the tropopause region.

Low tritium partial pressure permeation system for mass transport measurement in lead lithium eutectic

DOE PAGES

Pawelko, R. J.; Shimada, M.; Katayama, K.; ...

2015-11-28

This paper describes a new experimental system designed to investigate tritium mass transfer properties in materials important to fusion technology. Experimental activities were carried out at the Safety and Tritium Applied Research (STAR) facility located at the Idaho National Laboratory (INL). The tritium permeation measurement system was developed as part of the Japan/US TITAN collaboration to investigate tritium mass transfer properties in liquid lead lithium eutectic (LLE) alloy. The experimental system is configured to measure tritium mass transfer properties at low tritium partial pressures. Initial tritium permeation scoping tests were conducted on a 1 mm thick α-Fe plate to determinemore » operating parameters and to validate the experimental technique. A second series of permeation tests was then conducted with the α-Fe plate covered with an approximately 8.5 mm layer of liquid lead lithium eutectic alloy (α-Fe/LLE). We present preliminary tritium permeation data for α-Fe and α-Fe/LLE at temperatures between 400 and 600°C and at tritium partial pressures between 1.7E-3 and 2.5 Pa in helium. Preliminary results for the α-Fe plate and α-Fe/LLE indicate that the data spans a transition region between the diffusion-limited regime and the surface-limited regime. In conclusion, additional data is required to determine the existence and range of a surface-limited regime.« less

The effect of partial portal decompression on portal blood flow and effective hepatic blood flow in man: a prospective study.

PubMed

Rosemurgy, A S; McAllister, E W; Godellas, C V; Goode, S E; Albrink, M H; Fabri, P J

1995-12-01

With the advent of transjugular intrahepatic porta-systemic stent shunt and the wider application of the surgically placed small diameter prosthetic H-graft portacaval shunt (HGPCS), partial portal decompression in the treatment of portal hypertension has received increased attention. The clinical results supporting the use of partial portal decompression are its low incidence of variceal rehemorrhage due to decreased portal pressures and its low rate of hepatic failure, possibly due to maintenance of blood flow to the liver. Surprisingly, nothing is known about changes in portal hemodynamics and effective hepatic blood flow following partial portal decompression. To prospectively evaluate changes in portal hemodynamics and effective hepatic blood flow brought about by partial portal decompression, the following were determined in seven patients undergoing HGPCS: intraoperative pre- and postshunt portal vein pressures and portal vein-inferior vena cava pressure gradients, intraoperative pre- and postshunt portal vein flow, and pre- and postoperative effective hepatic blood flow. With HGPCS, portal vein pressures and portal vein-inferior vena cava pressure gradients decreased significantly, although portal pressures remained above normal. In contrast to the significant decreases in portal pressures, portal vein blood flow and effective hepatic blood flow do not decrease significantly. Changes in portal vein pressures and portal vein-inferior vena cava pressure gradients are great when compared to changes in portal vein flow and effective hepatic blood flow. Reduction of portal hypertension with concomitant maintenance of hepatic blood flow may explain why hepatic dysfunction is avoided following partial portal decompression.

The Effect of Oxygen Partial Pressure on Microstructure and Properties of Fe40Al Alloy Sintered under Vacuum

PubMed Central

Siemiaszko, Dariusz; Kowalska, Beata; Jóźwik, Paweł; Kwiatkowska, Monika

2015-01-01

This paper presents the results of studies on the influence of oxygen partial pressure (vacuum level in the chamber) on the properties of FeAl intermetallics. One of the problems in the application of classical methods of prepared Fe-Al intermetallic is the occurrence of oxides. Applying a vacuum during sintering should reduce this effect. In order to analyze the effect of oxygen partial pressure on sample properties, five samples were processed (by a pressure-assisted induction sintering—PAIS method) under the following pressures: 3, 8, 30, 80, and 300 mbar (corresponding to oxygen partial pressures of 0.63, 1.68, 6.3, 16.8, and 63 mbar, respectively). The chemical and phase composition, hardness, density, and microstructure observations indicate that applying a vacuum significantly impacts intermetallic samples. The compact sintered at pressure 3 mbar is characterized by the most homogeneous microstructure, the highest density, high hardness, and nearly homogeneous chemical composition. PMID:28788015

Exposure of Arabidopsis thaliana to Hypobaric Environments: Implications for Low-Pressure Bioregenerative Life Support Systems for Human Exploration Missions and Terraforming on Mars

NASA Astrophysics Data System (ADS)

Richards, Jeffrey T.; Corey, Kenneth A.; Paul, Anna-Lisa; Ferl, Robert J.; Wheeler, Raymond M.; Schuerger, Andrew C.

2006-12-01

Understanding how hypobaria can affect net photosynthetic (P net) and net evapotranspiration rates of plants is important for the Mars Exploration Program because low-pressured environments may be used to reduce the equivalent system mass of near-term plant biology experiments on landers or future bioregenerative advanced life support systems. Furthermore, introductions of plants to the surface of a partially terraformed Mars will be constrained by the limits of sustainable growth and reproduction of plants to hypobaric conditions. To explore the effects of hypobaria on plant physiology, a low-pressure growth chamber (LPGC) was constructed that maintained hypobaric environments capable of supporting short-term plant physiological studies. Experiments were conducted on Arabidopsis thaliana maintained in the LPGC with total atmospheric pressures set at 101 (Earth sea-level control), 75, 50, 25 or 10 kPa. Plants were grown in a separate incubator at 101 kPa for 6 weeks, transferred to the LPGC, and acclimated to low-pressure atmospheres for either 1 or 16 h. After 1 or 16 h of acclimation, CO2 levels were allowed to drawdown from 0.1 kPa to CO2 compensation points to assess P net rates under different hypobaric conditions. Results showed that P net increased as the pressures decreased from 101 to 10 kPa when CO2 partial pressure (pp) values were below 0.04 kPa (i.e., when ppCO2 was considered limiting). In contrast, when ppCO2 was in the nonlimiting range from 0.10 to 0.07 kPa, the P net rates were insensitive to decreasing pressures. Thus, if CO2 concentrations can be kept elevated in hypobaric plant growth modules or on the surface of a partially terraformed Mars, P net rates may be relatively unaffected by hypobaria. Results support the conclusions that (i) hypobaric plant growth modules might be operated around 10 kPa without undue inhibition of photosynthesis and (ii) terraforming efforts on Mars might require a surface pressure of at least 10 kPa (100 mb) for normal growth of deployed plant species.

Exposure of Arabidopsis thaliana to hypobaric environments: implications for low-pressure bioregenerative life support systems for human exploration missions and terraforming on Mars.

PubMed

Richards, Jeffrey T; Corey, Kenneth A; Paul, Anna-Lisa; Ferl, Robert J; Wheeler, Raymond M; Schuerger, Andrew C

2006-12-01

Understanding how hypobaria can affect net photosynthetic (P (net)) and net evapotranspiration rates of plants is important for the Mars Exploration Program because low-pressured environments may be used to reduce the equivalent system mass of near-term plant biology experiments on landers or future bioregenerative advanced life support systems. Furthermore, introductions of plants to the surface of a partially terraformed Mars will be constrained by the limits of sustainable growth and reproduction of plants to hypobaric conditions. To explore the effects of hypobaria on plant physiology, a low-pressure growth chamber (LPGC) was constructed that maintained hypobaric environments capable of supporting short-term plant physiological studies. Experiments were conducted on Arabidopsis thaliana maintained in the LPGC with total atmospheric pressures set at 101 (Earth sea-level control), 75, 50, 25 or 10 kPa. Plants were grown in a separate incubator at 101 kPa for 6 weeks, transferred to the LPGC, and acclimated to low-pressure atmospheres for either 1 or 16 h. After 1 or 16 h of acclimation, CO(2) levels were allowed to drawdown from 0.1 kPa to CO(2) compensation points to assess P (net) rates under different hypobaric conditions. Results showed that P (net) increased as the pressures decreased from 101 to 10 kPa when CO(2) partial pressure (pp) values were below 0.04 kPa (i.e., when ppCO2 was considered limiting). In contrast, when ppCO(2) was in the nonlimiting range from 0.10 to 0.07 kPa, the P (net) rates were insensitive to decreasing pressures. Thus, if CO(2 )concentrations can be kept elevated in hypobaric plant growth modules or on the surface of a partially terraformed Mars, P (net) rates may be relatively unaffected by hypobaria. Results support the conclusions that (i) hypobaric plant growth modules might be operated around 10 kPa without undue inhibition of photosynthesis and (ii) terraforming efforts on Mars might require a surface pressure of at least 10 kPa (100 mb) for normal growth of deployed plant species.

Influence of oxygen partial pressure on the microstructural and magnetic properties of Er-doped ZnO thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Wei-Bin; Li, Fei; Chen, Hong-Ming

2015-06-15

Er-doped ZnO thin films have been prepared by using inductively coupled plasma enhanced physical vapor deposition at different O{sub 2}:Ar gas flow ratio (R = 0:30, 1:30, 1:15, 1:10 and 1:6). The influence of oxygen partial pressure on the structural, optical and magnetic properties was studied. It is found that an appropriate oxygen partial pressure (R=1:10) can produce the best crystalline quality with a maximum grain size. The internal strain, estimated by fitting the X-ray diffraction peaks, varied with oxygen partial pressure during growth. PL measurements show that plenty of defects, especially zinc vacancy, exist in Er-doped ZnO films. Allmore » the samples show room-temperature ferromagnetism. Importantly, the saturation magnetization exhibits similar dependency on oxygen partial pressure with the internal strain, which indicates that internal strain has an important effect on the magnetic properties of Er-doped ZnO thin films.« less

Anatomic partial nephrectomy: technique evolution.

PubMed

Azhar, Raed A; Metcalfe, Charles; Gill, Inderbir S

2015-03-01

Partial nephrectomy provides equivalent long-term oncologic and superior functional outcomes as radical nephrectomy for T1a renal masses. Herein, we review the various vascular clamping techniques employed during minimally invasive partial nephrectomy, describe the evolution of our partial nephrectomy technique and provide an update on contemporary thinking about the impact of ischemia on renal function. Recently, partial nephrectomy surgical technique has shifted away from main artery clamping and towards minimizing/eliminating global renal ischemia during partial nephrectomy. Supported by high-fidelity three-dimensional imaging, novel anatomic-based partial nephrectomy techniques have recently been developed, wherein partial nephrectomy can now be performed with segmental, minimal or zero global ischemia to the renal remnant. Sequential innovations have included early unclamping, segmental clamping, super-selective clamping and now culminating in anatomic zero-ischemia surgery. By eliminating 'under-the-gun' time pressure of ischemia for the surgeon, these techniques allow an unhurried, tightly contoured tumour excision with point-specific sutured haemostasis. Recent data indicate that zero-ischemia partial nephrectomy may provide better functional outcomes by minimizing/eliminating global ischemia and preserving greater vascularized kidney volume. Contemporary partial nephrectomy includes a spectrum of surgical techniques ranging from conventional-clamped to novel zero-ischemia approaches. Technique selection should be tailored to each individual case on the basis of tumour characteristics, surgical feasibility, surgeon experience, patient demographics and baseline renal function.

Effects of oxygen partial pressure on Li-air battery performance

NASA Astrophysics Data System (ADS)

Kwon, Hyuk Jae; Lee, Heung Chan; Ko, Jeongsik; Jung, In Sun; Lee, Hyun Chul; Lee, Hyunpyo; Kim, Mokwon; Lee, Dong Joon; Kim, Hyunjin; Kim, Tae Young; Im, Dongmin

2017-10-01

For application in electric vehicles (EVs), the Li-air battery system needs an air intake system to supply dry oxygen at controlled concentration and feeding rate as the cathode active material. To facilitate the design of such air intake systems, we have investigated the effects of oxygen partial pressure (≤1 atm) on the performance of the Li-air cell, which has not been systematically examined. The amounts of consumed O2 and evolved CO2 from the Li-air cell are measured with a custom in situ differential electrochemical gas chromatography-mass spectrometry (DEGC-MS). The amounts of consumed O2 suggest that the oxygen partial pressure does not affect the reaction mechanism during discharge, and the two-electron reaction occurs under all test conditions. On the other hand, the charging behavior varies by the oxygen partial pressure. The highest O2 evolution ratio is attained under 70% O2, along with the lowest CO2 evolution. The cell cycle life also peaks at 70% O2 condition. Overall, an oxygen partial pressure of about 0.5-0.7 atm maximizes the Li-air cell capacity and stability at 1 atm condition. The findings here indicate that the appropriate oxygen partial pressure can be a key factor when developing practical Li-air battery systems.

Human respiration at rest in rapid compression and at high pressures and gas densities

NASA Technical Reports Server (NTRS)

Gelfand, R.; Lambertsen, C. J.; Strauss, R.; Clark, J. M.; Puglia, C. D.

1983-01-01

The ventilation (V), end-tidal PCO2 (PACO2), and CO2 elimination rate were determined in men at rest breathing CO2-free gas over the pressure range 1-50 ATA and the gas density range 0.4-25 g/l, during slow and rapid compressions, at stable elevated ambient pressures and during slow decompressions. Progressive increase in pulmonary gas flow resistance due to elevation of ambient pressure and inspired gas density to the He-O2 equivalent of 5000 feet of seawater was found to produce a complex pattern of change in PACO2. It was found that as both ambient pressure and pulmonary gas flow resistance were progressively raised, PACO2 at first increased, went through a maximum, and then declined towards values near the 1 ATA level. It is concluded that this pattern of PACO2 change results from the interaction on ventilation of the increase in pulmonary resistance due to the elevation of gas density with the increase in respiratory drive postulated as due to generalized central nervous system excitation associated with exposure to high hydrostatic pressure. It is suggested that a similar interaction exists between increased gas flow resistance and the increase in respiratory drive related to nitrogen partial pressure and the resulting narcosis.

Sapwood development in Pinus radiata trees grown for three years at ambient and elevated carbon dioxide partial pressures.

PubMed

Atwell, B J; Henery, M L; Whitehead, D

2003-01-01

Clonal trees of Pinus radiata D. Don were grown in open-top chambers at a field site in New Zealand for 3 years at ambient (37 Pa) or elevated (65 Pa) carbon dioxide (CO2) partial pressure. Nitrogen (N) was supplied to half of the trees in each CO2 treatment, at 15 g N m-2 in the first year and 60 g N m-2 in the subsequent 2 years (high-N treatment). Trees in the low-N treatment were not supplied with N but received the same amount of other nutrients as trees in the high-N treatment. In the first year, stem basal area increased more in trees growing at elevated CO2 partial pressure and high-N supply than in control trees, suggesting a positive interaction between these resources. However, the relative rate of growth became the same across trees in all treatments after 450 days, resulting in trees growing at elevated CO2 partial pressure and high-N supply having larger basal areas than trees in the other treatments. Sapwood N content per unit dry mass was consistently about 0.09% in all treatments, indicating that N status was not suppressed by elevated CO2 partial pressure. Thus, during the first year of growth, an elevated CO2 partial pressure enhanced carbon (C) and N storage in woody stems, but there was no further stimulus to C and N deposition after the first year. The chemical composition of sapwood was unaffected by elevated CO2 partial pressure, indicating that no additional C was sequestered through lignification. However, independent of the treatments, early wood was 13% richer in lignin than late wood. Elevated CO2 partial pressure decreased the proportion of sapwood occupied by the lumina of tracheids by up to 12%, indicating increased sapwood density in response to CO2 enrichment. This effect was probably a result of thicker tracheid walls rather than narrower lumina.

Alternative backing up pump for turbomolecular pumps

DOEpatents

Myneni, Ganapati Rao

2003-04-22

As an alternative to the use of a mechanical backing pump in the application of wide range turbomolecular pumps in ultra-high and extra high vacuum applications, palladium oxide is used to convert hydrogen present in the evacuation stream and related volumes to water with the water then being cryo-pumped to a low pressure of below about 1.e.sup.-3 Torr at 150.degree. K. Cryo-pumping is achieved using a low cost Kleemenco cycle cryocooler, a somewhat more expensive thermoelectric cooler, a Venturi cooler or a similar device to achieve the required minimization of hydrogen partial pressure.

Using Dalton's Law of Partial Pressures to Determine the Vapor Pressure of a Volatile Liquid

ERIC Educational Resources Information Center

Hilgeman, Fred R.; Bertrand, Gary; Wilson, Brent

2007-01-01

This experiment, designed for a general chemistry laboratory, illustrates the use of Dalton's law of partial pressures to determine the vapor pressure of a volatile liquid. A predetermined volume of air is injected into a calibrated tube filled with a liquid whose vapor pressure is to be measured. The volume of the liquid displaced is greater than…

Bio-syngas production from agro-industrial biomass residues by steam gasification.

PubMed

Pacioni, Tatiana Ramos; Soares, Diniara; Domenico, Michele Di; Rosa, Maria Fernanda; Moreira, Regina de Fátima Peralta Muniz; José, Humberto Jorge

2016-12-01

This study evaluated the steam gasification potential of three residues from Brazilian agro-industry by assessing their reaction kinetics and syngas production at temperatures from 650 to 850°C and a steam partial pressure range of 0.05 to 0.3bar. The transition temperature between kinetic control and diffusion control regimes was identified. Prior to the gasification tests, the raw biomasses, namely apple pomace, spent coffee grounds and sawdust, were pyrolyzed in a fixed-bed quartz tubular reactor under controlled conditions. Gasification tests were performed isothermally in a magnetic suspension thermobalance and the reaction products were analyzed by a gas chromatograph with TCD/FID detectors. According to the characterization results, the samples presented higher carbon and lower volatile matter contents than the biomasses. Nevertheless, all of the materials had high calorific value. Syngas production was influenced by both temperature and steam partial pressure. Higher concentrations of H 2 and CO were found in the conversion range of 50-80% and higher concentrations of CO 2 in conversions around 10%, for all the gasified biochars. The H 2 /CO decreased with increasing temperature, mainly in kinetic control regime, in the lower temperature range. The results indicate the gasification potential of Brazilian biomass residues and are an initial and important step in the development of gasification processes in Brazil. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of nacelles on aerodynamic characteristics of an executive-jet model with simulated, partial-chord, laminar-flow-control wing glove

NASA Technical Reports Server (NTRS)

Campbell, R. L.

1982-01-01

Tests were conducted in the Langley High-Speed 7- by 10-Foot Tunnel using a 1/10-scale model of an executive jet to examine the effects of the nacelles on the wing pressures and model longitudinal aerodynamic characteristics. For the present investigation, each wing panel was modified with a simulated, partial-chord, laminar-flow-control glove. Horizontal-tail effects were also briefly examined. The tests covered a range of Mach numbers from 0.40 to 0.82 and lift coefficients from 0.20 to 0.55. Oil-flow photographs of the wing at selected conditions are included.

Oxygen partial pressure sensor

DOEpatents

Dees, D.W.

1994-09-06

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

Oxygen partial pressure sensor

DOEpatents

Dees, Dennis W.

1994-01-01

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

Tibiofemoral contact pressures in radial tears of the meniscus treated with all-inside repair, inside-out repair and partial meniscectomy.

PubMed

Zhang, Alan L; Miller, Stephanie L; Coughlin, Dezba G; Lotz, Jeffrey C; Feeley, Brian T

2015-10-01

To test contact pressures in the knee after treatment of a radial meniscus tear with an all-inside meniscal repair technique and compare the results with inside-out repair and partial meniscectomy. Six non-paired cadaveric knees were analyzed with intra-compartment pressures measured at loads of 250 N, 500 N and 1000 N at 0°, eight degrees, 15°, and 30° of knee flexion. Compartmental contact pressures were measured for the intact medial meniscus, radial tear in the posterior horn, all-inside repair using the NovoStitch suture passer device (Ceterix Orthopaedics Inc., Menlo Park, CA), inside-out repair method, and partial meniscectomy. One-way ANOVA was used for statistical analysis. The greatest differences in peak pressures between treatments were observed under 1000 N load at 30° flexion (0.8± (SD) 0.1 MPa (intact meniscus), 0.8± (SD) 0.1 MPa (all-inside), 0.9± (SD) 0.1 MPa (inside-out) and 1.6± (SD) 0.2 MPa (partial meniscectomy)). Treatment with partial meniscectomy resulted in the highest peak pressures compared to all other states (p<0.0001 at each angle). Repair of the radial tear using the all-inside technique as well as the inside-out technique resulted in significantly decreased compartment pressures compared to partial meniscectomies (p<0.0001 at each angle). There were no significant differences between peak pressures in the intact state and after repair with the all-inside or inside-out techniques. An all-inside repair technique using the NovoStitch suture passer can decrease contact pressures for a radial meniscus tear similarly to the inside-out repair technique when compared to partial meniscectomy. This novel arthroscopic suture passer warrants further analysis in the clinical setting as it may be a reliable method for repair of radial meniscal tears through an arthroscopic all-inside technique. Copyright © 2015 Elsevier B.V. All rights reserved.

The influence of participant characteristics on the relationship between cuff pressure and level of blood flow restriction.

PubMed

Hunt, Julie E A; Stodart, Clare; Ferguson, Richard A

2016-07-01

Previous investigations to establish factors influencing the blood flow restriction (BFR) stimulus have determined cuff pressures required for complete arterial occlusion, which does not reflect the partial restriction prescribed for this training technique. This study aimed to establish characteristics that should be accounted for when prescribing cuff pressures required for partial BFR. Fifty participants were subjected to incremental blood flow restriction of the upper and lower limbs by proximal pneumatic cuff inflation. Popliteal and brachial artery diameter, blood velocity and blood flow was assessed with Doppler ultrasound. Height, body mass, limb circumference, muscle-bone cross-sectional area, adipose thickness (AT) and arterial blood pressure were measured and used in different models of hierarchical linear regression to predict the pressure at which 60 % BFR (partial occlusion) occurred. Combined analysis revealed a difference in cuff pressures required to elicit 60 % BFR in the popliteal (111 ± 12 mmHg) and brachial arteries (101 ± 12 mmHg). MAP (r = 0.58) and AT (r = -0.45) were the largest independent determinants of lower and upper body partial occlusion pressures. However, greater variance was explained by upper and lower limb regression models composed of DBP and BMI (48 %), and arm AT and DBP (30 %), respectively. Limb circumference has limited impact on the cuff pressure required for partial blood flow restriction which is in contrast to its recognised relationship with complete arterial occlusion. The majority of the variance in partial occlusion pressure remains unexplained by the predictor variables assessed in the present study.

Physical and chemical properties of San Francisco Bay, California, 1980

USGS Publications Warehouse

Ota, Allan Y.; Schemel, L.E.; Hager, S.W.

1989-01-01

The U.S. Geological Survey conducted hydrologic investigations in both the deep water channels and the shallow-water regions of the San Francisco Bay estuarine system during 1980. Cruises were conducted regularly, usually at two-week intervals. Physical and chemical properties presented in this report include temperature , salinity, suspended particulate matter, turbidity, extinction coefficient, partial pressure of CO2, partial pressure of oxygen , dissolved organic carbon, particulate organic carbon, discrete chlorophyll a, fluorescence of photosynthetic pigments, dissolved silica, dissolved phosphate, nitrate plus nitrite, nitrite, ammonium, dissolved inorganic nitrogen, dissolved nitrogen, dissolved phosphorus, total nitrogen, and total phosphorus. Analytical methods are described. The body of data contained in this report characterizes hydrologic conditions in San Francisco Bay during a year with an average rate of freshwater inflow to the estuary. Concentrations of dissolved silica (discrete-sample) ranged from 3.8 to 310 micro-M in the northern reach of the bay, whereas the range in the southern reach was limited to 63 to 150 micro-M. Concentrations of phosphate (discrete-sample) ranged from 1.3 to 4.4 micro-M in the northern reach, which was narrow in comparison with that of 2.2 to 19.0 micro-M in the southern reach. Concentrations of nitrate plus nitrite (discrete-sample) ranged from near zero to 53 micro-M in the northern reach, and from 2.3 to 64 micro-M in the southern reach. Concentrations of nitrite (discrete-sample) were low in both reaches, exhibiting a range from nearly zero to approximately 2.3 micro-M. Concentrations of ammonium (discrete-sample) ranged from near zero to 14.2 micro-M in the northern reach, and from near zero to 8.3 micro-M in the southern reach. (USGS)

Interparticle collision of natural sediment grains in water

USGS Publications Warehouse

Schmeeckle, Mark W.; Nelson, Jonathan M.; Pitlick, John; Bennett, James P.

2001-01-01

Elastohydrodynamic theory and measurements of particle impacts on an inclined glass plane in water are used to investigate the mechanics of interparticle collisions in sediment‐transporting flows. A collision Stokes number is proposed as a measure of the momentum of an interparticle collision versus the viscous pressure force in the interstitial gap between colliding particles. The viscous pressure force opposes motion of the particles on approach and rebound. A Stokes number of between 39 and 105 is estimated as the critical range below which particle impacts are completely viscously damped and above which impacts are partially elastic. The critical Stokes number is shown to roughly coincide with the Bagnold number transition between macroviscous and grain inertial debris flows and the transition between damped and partially elastic bed load transport saltation impacts. The nonspherical nature of natural particles significantly alters the motion of the center of mass after a partially elastic collision. The normal to the point of contact between the particles does not necessarily go through the center of mass. Thus normal rebound of the center of mass may not occur. A model of particle motion after rebound for particles of arbitrary shape, conserving both linear and angular momentum, is proposed.

Alumina Volatility in Water Vapor at Elevated Temperatures: Application to Combustion Environments

NASA Technical Reports Server (NTRS)

Opila, Elizabeth J.; Myers, Dwight L.

2003-01-01

The volatility of alumina in high temperature water vapor was determined by measuring weight loss of sapphire coupons at temperatures between 1250 and 1500 C, water vapor partial pressures between 0.15 and 0.68 atm in oxygen, at one atmosphere total pressure, and a gas velocity of 4.4 centimeters per second. The variation of the volatility with water vapor partial pressure was consistent with Al(OH)3(g) formation. The enthalpy of reaction to form Al(OH)3(g) from alumina and water vapor was found to be 210 plus or minus 20 kJ/mol. Surface rearrangement of ground sapphire surfaces increased with water vapor partial pressure, temperature and volatility rate. Recession rates of alumina due to volatility were determined as a function of water vapor partial pressure and temperature to evaluate limits for use of alumina in long term applications in combustion environments.

Non-invasive multiwavelength photoplethysmography under low partial pressure of oxygen.

PubMed

Fang, Yung Chieh; Tai, Cheng-Chi

2016-08-01

A reduction in partial pressure of oxygen in the environment may be caused by a gain in altitude, which reduces the atmospheric pressure; it may also be caused by the carbon dioxide generated from breathing in an enclosed space. Does inhaling oxygen of lower partial pressure affect the oxygen-carrying function of haemoglobin in vivo? This study uses non-invasive multiwavelength photoplethysmography to measure the effects that inhaling this type of oxygen can have on the plethysmography of the appendages of the body (fingertips). The results indicate that under low partial pressure of oxygen, be it the result of a gain in carbon dioxide concentration or altitude, the change in visible light absorption is the biggest for short wavelengths (approximately 620 or 640 nm) near deoxyhaemoglobin, which has higher absorption coefficient. Moreover, increasing carbon dioxide concentration from 5000 to 10,000 ppm doubly reduces the absorption rate of these short wavelengths.

Performance Evaluation of an Oxygen Sensor as a Function of the Samaria Doped Ceria Film Thickness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanghavi, Rahul P.; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T

The current demand in the automobile industry is in the control of air-fuel mixture in the combustion engine of automobiles. Oxygen partial pressure can be used as an input parameter for regulating or controlling systems in order to optimize the combustion process. Our goal is to identify and optimize the material system that would potentially function as the active sensing material for such a device that monitors oxygen partial pressure in these systems. We have used thin film samaria doped ceria (SDC) as the sensing material for the sensor operation, exploiting the fact that at high temperatures, oxygen vacancies generatedmore » due to samarium doping act as conducting medium for oxygen ions which hop through the vacancies from one side to the other contributing to an electrical signal. We have recently established that 6 atom % Sm doping in ceria films has optimum conductivity. Based on this observation, we have studied the variation in the overall conductivity of 6 atom % samaria doped ceria thin films as a function of thickness in the range of 50 nm to 300 nm at a fixed bias voltage of 2 volts. A direct proportionality in the increase in the overall conductivity is observed with the increase in sensing film thickness. For a range of oxygen pressure values from 1 mTorr to 100 Torr, a tolerable hysteresis error, good dynamic response and a response time of less than 10 seconds was observed« less

Thermal equation of state of TiC: A synchrotron x-ray diffraction study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu Xiaohui; National Lab for Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080; Department of Physics, University of Science and Technology of China, Hefei 230026

2010-06-15

The pressure-volume-temperature measurements were carried out for titanium carbide (TiC) at pressures and temperatures up to 8.1 GPa and 1273 K using energy-dispersive synchrotron x-ray diffraction. Thermoelastic parameters were derived for TiC based on a modified high-temperature Birch-Murnaghan equation of state and a thermal pressure approach. With the pressure derivative of the bulk modulus, K{sub 0}{sup '}, fixed at 4.0, we obtain: the ambient bulk modulus K{sub 0}=268(6) GPa, which is comparable to previously reported value; temperature derivative of bulk modulus at constant pressure ({partial_derivative}K{sub T}/{partial_derivative}T){sub P}=-0.026(9) GPa K{sup -1}, volumetric thermal expansivity {alpha}{sub T}(K{sup -1})=a+bT with a=1.62(12)x10{sup -5} K{supmore » -1} and b=1.07(17)x10{sup -8} K{sup -2}, pressure derivative of thermal expansion ({partial_derivative}{alpha}/{partial_derivative}P){sub T}=(-3.62{+-}1.14)x10{sup -7} GPa{sup -1} K{sup -1}, and temperature derivative of bulk modulus at constant volume ({partial_derivative}K{sub T}/{partial_derivative}T){sub V}=-0.015(8) GPa K{sup -1}. These results provide fundamental thermophysical properties for TiC for the first time and are important to theoretical and computational modeling of transition metal carbides.« less

Thermal equation-of-state of TiC: a synchrotron x-ray diffraction study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Xiaohui; Lin, Zhijun; Zhang, Jianzhong

2009-01-01

The pressure (P)-volume (V)-temperature (T) measurements were carried out for titanium carbide at pressures and temperatures up to 8.1 GPa and 1273 K using energy-dispersive synchrotron x-ray diffraction. Thermoelastic parameters were derived for TiC based on a modified high-temperature Birch-Murnaghan equation of state and a thermal-pressure approach. With the pressure derivative of the bulk modulus, K'{sub 0}, fixed at 4.0, we obtain: the ambient bulk modulus K{sub 0} = 268(6) GPa, temperature derivative of bulk modulus at constant pressure ({partial_derivative}K{sub T}/{partial_derivative}T){sub p} = -0.026(9) GPa K{sup -1}, volumetric thermal expansivity a{sub T}(K{sup -1}) = a + bT with a =more » 1.62(12) x 10{sup -5} K{sup -1} and b = 1.07(17) x 10{sup -8} K{sup -2}, pressure derivative of thermal expansion ({partial_derivative}a/{partial_derivative}P){sub T} = (-3.62 {+-} 1.14) x 10{sup -7} GPa{sup -1} K{sup -1}, and temperature derivative of bulk modulus at constant volume ({partial_derivative}K{sub T}/{partial_derivative}T){sub v} = -0.015 (8) GPa K{sup -1}. These results provide fundamental thermo physical properties for TiC and are important to theoretical and computational modeling of transition metal carbides.« less

Effect of O 2 gas partial pressure on structures and dielectric characteristics of rf sputtered ZrO 2 thin films

NASA Astrophysics Data System (ADS)

Ma, C. Y.; Lapostolle, F.; Briois, P.; Zhang, Q. Y.

2007-08-01

Amorphous and polycrystalline zirconium oxide thin films have been deposited by reactive rf magnetron sputtering in a mixed argon/oxygen or pure oxygen atmosphere with no intentional heating of the substrate. The films were characterized by high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and capacitance versus voltage ( C- V) measurements to investigate the variation of structure, surface morphology, thickness of SiO 2-like interfacial layer as well as dielectric characteristics with different oxygen partial pressures. The films deposited at low oxygen partial pressures (less than 15%) are amorphous and dense with a smooth surface. In contrast, the films prepared at an oxygen partial pressure higher than 73% are crystallized with the microstructure changing from the mixture of monoclinic and tetragonal phases to a single monoclinic structure. The film structural transition is believed to be consequences of decrease in the oxygen vacancy concentration in the film and of increase of the energetically neutral particles in the plasma due to an increased oxygen partial pressure. SE measurements showed that significant interfacial SiO 2 growth has taken place above approximately 51%. The best C- V results in terms of relative dielectric constant values are obtained for thin films prepared at an oxygen partial pressure of 15%.

Precise predictions of H2O line shapes over a wide pressure range using simulations corrected by a single measurement

NASA Astrophysics Data System (ADS)

Ngo, N. H.; Nguyen, H. T.; Tran, H.

2018-03-01

In this work, we show that precise predictions of the shapes of H2O rovibrational lines broadened by N2, over a wide pressure range, can be made using simulations corrected by a single measurement. For that, we use the partially-correlated speed-dependent Keilson-Storer (pcsdKS) model whose parameters are deduced from molecular dynamics simulations and semi-classical calculations. This model takes into account the collision-induced velocity-changes effects, the speed dependences of the collisional line width and shift as well as the correlation between velocity and internal-state changes. For each considered transition, the model is corrected by using a parameter deduced from its broadening coefficient measured for a single pressure. The corrected-pcsdKS model is then used to simulate spectra for a wide pressure range. Direct comparisons of the corrected-pcsdKS calculated and measured spectra of 5 rovibrational lines of H2O for various pressures, from 0.1 to 1.2 atm, show very good agreements. Their maximum differences are in most cases well below 1%, much smaller than residuals obtained when fitting the measurements with the Voigt line shape. This shows that the present procedure can be used to predict H2O line shapes for various pressure conditions and thus the simulated spectra can be used to deduce the refined line-shape parameters to complete spectroscopic databases, in the absence of relevant experimental values.

Preparation and characterization of ceramic sensors for use at elevated temperatures

NASA Astrophysics Data System (ADS)

You, Tao

Ceramic ITO strain sensors were prepared by reactive sputtering in various nitrogen/oxygen/argon partial pressures. The thickness of the active ITO strain elements played a significant role in the high temperature stability and piezoresistive properties, specifically, these results indicated that both gauge factor and drift rate were affected by the thickness of ITO films comprising the active strain elements. The influence of nitrogen in the reactive sputtered ITO films on the microstructure and the high temperature piezoresistive properties was also investigated. Scanning electron microscopy (SEM) revealed a partially sintered microstructure consisting of a contiguous network of sub-micron ITO particles with well-defined necks and isolated nanoporosity. Sintering and densification of the ITO particles containing these nitrogen rich grain boundaries was retarded and a contiguous network of nano-sized ITO particles was established. Aluminum doped indium tin oxide thin film exhibited an enhanced high temperature stability compared with undoped ITO thin film. The effect of aluminum doped ITO was investigated under various preparation and testing environments. Electron spectroscopy for chemical analysis (ESCA) studies indicated that interfacial reactions between ITO and aluminum increased the stability of ITO at elevated temperatures. These binding energies of indium-indium are significantly higher than those associated with stoichiometric indium oxide. A robust ceramic temperature sensor was fabricated by two different ITO elements, each with substantially different charge carrier concentrations. Thermal cycling of ITO thin films in a varied of partial oxygen pressures conditions showed that temperature coefficient of resistance (TCR) was nearly independent of oxygen partial pressure. A thermoelectric power of 6.0muV/°C and a linear voltage-temperature response were measured for an ITO thin film ceramic thermocouple over the temperature range 25--1250°C.

A high-resolution superconducting pressure control system for use at low temperatures

NASA Astrophysics Data System (ADS)

Geng, Z. K.; Swanson, D. R.; Nissen, J. A.; Lipa, J. A.

2000-01-01

We have developed a high resolution superconducting pressure gauge and controller system capable of stabilizing pressure to within +/-10-8 bar in the range 0-30 bars at temperatures below about 6K. The system consists of two parts: a transducer and a pressure actuator. The transducer is based on the inductive sensing of the position of a diaphragm using superconducting techniques. A rod attached to the center of the diaphragm supports a superconducting plate which is in close proximity to a flat, spiral superconducting coil. A persistent current of about 1 A is trapped in the coil and is coupled to a dc SQUID magnetometer. The magnetometer produces a partially digitized dc output proportional to the change of pressure applied to the diaphragm. Because of the ability of the magnetometer to count magnetic flux quanta, an extremely wide dynamic range can be achieved with high sensitivity and repeatability. The transducer was used to control the pressure of a sample of liquid helium at temperatures near 2 K and pressures from 1-25 bars. The actuator consisted of two parts: a thermally isolated chamber filled with 3He that could be heated and cooled as desired over the range 1.5 to 10 K, and a beryllium-copper diaphragm assembly. This diaphragm had the 3He on one side and the sample helium on the other. A simple servomechanism was used to convert the output signal from the magnetometer to heat applied to the 3He chamber. The system has been operated routinely over the full range of pressures and so far no significant drift has been detected. It is somewhat sensitive to vibration and EMI, but otherwise appears quite robust. Plans have been made to improve the shielding to reduce the EMI susceptibility. The vibration sensitivity can be reduced by making use of a pair of pressure sensing diaphragms acting in opposite directions. .

Effects of hydrogen partial pressure on autotrophic growth and product formation of Acetobacterium woodii.

PubMed

Kantzow, Christina; Weuster-Botz, Dirk

2016-08-01

Low aqueous solubility of the gases for autotrophic fermentations (e.g., hydrogen gas) results in low productivities in bioreactors. A frequently suggested approach to overcome mass transfer limitation is to increase the solubility of the limiting gas in the reaction medium by increasing the partial pressure in the gas phase. An increased inlet hydrogen partial pressure of up to 2.1 bar (total pressure of 3.5 bar) was applied for the autotrophic conversion of hydrogen and carbon dioxide with Acetobacterium woodii in a batch-operated stirred-tank bioreactor with continuous gas supply. Compared to the autotrophic batch process with an inlet hydrogen partial pressure of 0.4 bar (total pressure of 1.0 bar) the final acetate concentration after 3.1 days was reduced to 50 % (29.2 g L(-1) compared to 59.3 g L(-1)), but the final formate concentration was increased by a factor of 18 (7.3 g L(-1) compared to 0.4 g L(-1)). Applying recombinant A. woodii strains overexpressing either genes for enzymes in the methyl branch of the Wood-Ljungdahl pathway or the genes phosphotransacetylase and acetate kinase at an inlet hydrogen partial pressure of 1.4 bar reduced the final formate concentration by up to 40 % and increased the final dry cell mass and acetate concentrations compared to the wild type strain. Solely the overexpression of the two genes for ATP regeneration at the end of the Wood-Ljungdahl pathway resulted in an initial switch off of formate production at increased hydrogen partial pressure until the maximum of the hydrogen uptake rate was reached.

Photosynthetic induction and its diffusional, carboxylation and electron transport processes as affected by CO2 partial pressure, temperature, air humidity and blue irradiance.

PubMed

Kaiser, Elias; Kromdijk, Johannes; Harbinson, Jeremy; Heuvelink, Ep; Marcelis, Leo F M

2017-01-01

Plants depend on photosynthesis for growth. In nature, factors such as temperature, humidity, CO 2 partial pressure, and spectrum and intensity of irradiance often fluctuate. Whereas irradiance intensity is most influential and has been studied in detail, understanding of interactions with other factors is lacking. We tested how photosynthetic induction after dark-light transitions was affected by CO 2 partial pressure (20, 40, 80 Pa), leaf temperatures (15·5, 22·8, 30·5 °C), leaf-to-air vapour pressure deficits (VPD leaf-air ; 0·5, 0·8, 1·6, 2·3 kPa) and blue irradiance (0-20 %) in tomato leaves (Solanum lycopersicum). Rates of photosynthetic induction strongly increased with CO 2 partial pressure, due to increased apparent Rubisco activation rates and reduced diffusional limitations. High leaf temperature produced slightly higher induction rates, and increased intrinsic water use efficiency and diffusional limitation. High VPD leaf-air slowed down induction rates and apparent Rubisco activation and (at 2·3 kPa) induced damped stomatal oscillations. Blue irradiance had no effect. Slower apparent Rubisco activation in elevated VPD leaf-air may be explained by low leaf internal CO 2 partial pressure at the beginning of induction. The environmental factors CO 2 partial pressure, temperature and VPD leaf-air had significant impacts on rates of photosynthetic induction, as well as on underlying diffusional, carboxylation and electron transport processes. Furthermore, maximizing Rubisco activation rates would increase photosynthesis by at most 6-8 % in ambient CO 2 partial pressure (across temperatures and humidities), while maximizing rates of stomatal opening would increase photosynthesis by at most 1-3 %. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Bulk YBa2Cu3O(x) superconductors through pressurized partial melt growth processing

NASA Technical Reports Server (NTRS)

Hu, S.; Hojaji, H.; Barkatt, A.; Boroomand, M.; Hung, M.; Buechele, A. C.; Thorpe, A. N.; Davis, D. D.; Alterescu, S.

1992-01-01

A novel pressurized partial melt growth process has been developed for producing large pieces of bulk Y-Ba-Cu-O superconductors. During long-time partial melt growth stage, an additional driving force for solidification is obtained by using pressurized oxygen gas. The microstructure and superconducting properties of the resulting samples were investigated. It was found that this new technique can eliminate porosity and inhomogeneity, promote large-scale grain-texturing, and improve interdomain coupling as well.

Annealing temperature and O2 partial pressure dependence of T(sub c) in HgBa2CuO(4+delta)

NASA Technical Reports Server (NTRS)

Xiong, Q.; Cao, Y.; Chen, F.; Xue, Y. Y.; Chu, C. W.

1994-01-01

Samples of HgBa2CuO(4+delta) (Hg-1201) were annealed under various conditions. After carefully controlling annealing time, annealing temperature (T(sub a)) and O2 partial pressure (P(sub 0)), we were able to find the reversible annealing conditions for Hg-1201. Under 1 atm O2 at 260 C less than or equal to T(sub a) less than or equal to 400 C, the obtained T(sub c) is nearly the same (approximately 97 K). However, it decreases quickly with T(sub a) greater than 300 C in high vacuum (P(sub 0) approximately 10(exp -8) atm), and reaches zero at T(sub a) = 400 C. On the other hand, T(sub c) decreases with the decrease of T(sub a) in high-pressure O2 (approximately 500 atm) and reaches approximately 20 K at about 240 C. In the entire annealing region, the oxygen surplus varies significantly from 0.03 to 0.4, and a wide range of T(sub c) variation (0 goes to 97 K goes to 20 K) was obtained with anion doping alone.

Extreme high temperature redox kinetics in ceria: exploration of the transition from gas-phase to material-kinetic limitations

DOE PAGES

Ji, Ho-Il; Davenport, Timothy C.; Gopal, Chirranjeevi Balaji; ...

2016-07-18

The redox kinetics of undoped ceria (CeO 2-δ) are investigated by the electrical conductivity relaxation method in the oxygen partial pressure range of -4.3 ≤ log(pO 2/atm) ≤ -2.0 at 1400 °C. It is demonstrated that extremely large gas flow rates, relative to the mass of the oxide, are required in order to overcome gas phase limitations and access the material kinetic properties. Using these high flow rate conditions, the surface reaction rate constant k chem is found to obey the correlation log(k chem/cm s -1) = (0.84 ± 0.02) × log(pO 2/atm) - (0.99 ± 0.05) and increases withmore » oxygen partial pressure. This increase contrasts the known behavior of the dominant defect species, oxygen vacancies and free electrons, which decrease in concentration with increasing oxygen partial pressure. For the sample geometries employed, diffusion was too fast to be detected. At low gas flow rates, the relaxation process becomes limited by the capacity of the sweep gas to supply/remove oxygen to/from the oxide. An analytical expression is derived for the relaxation in the gas-phase limited regime, and the result reveals an exponential decay profile, identical in form to that known for a surface reaction limited process. Thus, measurements under varied gas flow rates are required to differentiate between surface reaction limited and gas flow limited behavior.« less

Thin-film nano-thermogravimetry applied to praseodymium-cerium oxide films at high temperatures

NASA Astrophysics Data System (ADS)

Schröder, Sebastian; Fritze, Holger; Bishop, Sean; Chen, Di; Tuller, Harry L.

2018-05-01

High precision measurements of oxygen nonstoichiometry δ in thin film metal oxides MaOb±δ at elevated temperatures and controlled oxygen partial pressures pO2 are reported with the aid of resonant microbalances. The resonant microbalances applied here consisted of y-cut langasite (La3Ga5SiO14) and CTGS (Ca3TaGa3Si2O14) piezoelectric resonators, operated in the thickness shear mode at ˜5 MHz. Measurements of variations in δ of Pr0.1Ce0.9O2-δ (PCO) films are reported for the oxygen partial pressure range from 10-8 bar to 0.2 bar at 700 °C, and these results were found to be in good agreement with previously reported oxygen nonstoichiometry δ data derived from chemical capacitance studies. The PCO thin-films were deposited via pulsed laser deposition on both sides of the resonators, whose series resonance frequency was tracked, converted into mass changes and, finally, into nonstoichiometry. The nonstoichiometry was observed to reach a plateau as the oxygen partial pressure dropped below about 10-5 bar, the behavior being attributed to the full reduction of Pr to the trivalent state. These resonators enable stable operation up to temperatures above 1000 °C, thereby maintaining high mass resolution suitable for determining oxygen nonstoichiometry variations in thin films deposited on such resonators. For the given experimental conditions, a mass resolution of ˜50 ng was achieved at 700 °C with the CTGS resonator.

Electrical conductivity and thermopower of (1 - x) BiFeO(3) - xBi(0.5)K(0.5)TiO3 (x = 0.1, 0.2) ceramics near the ferroelectric to paraelectric phase transition.

PubMed

Wefring, E T; Einarsrud, M-A; Grande, T

2015-04-14

Ferroelectric BiFeO3 has attractive properties such as high strain and polarization, but a wide range of applications of bulk BiFeO3 are hindered due to high leakage currents and a high coercive electric field. Here, we report on the thermal behaviour of the electrical conductivity and thermopower of BiFeO3 substituted with 10 and 20 mol% Bi0.5K0.5TiO3. A change from p-type to n-type conductivity in these semi-conducting materials was demonstrated by the change in the sign of the Seebeck coefficient and the change in the slope of the isothermal conductivity versus partial pressure of O. A minimum in the isothermal conductivity was observed at ∼10(-2) bar O2 partial pressure for both solid solutions. The strong dependence of the conductivity on the partial pressure of O2 was rationalized by a point defect model describing qualitatively the conductivity involving oxidation/reduction of Fe(3+), the dominating oxidation state of Fe in stoichiometric BiFeO3. The ferroelectric to paraelectric phase transition of 80 and 90 mol% BiFeO3 was observed at 648 ± 15 and 723 ± 15 °C respectively by differential thermal analysis and confirmed by dielectric spectroscopy and high temperature powder X-ray diffraction.

Extreme high temperature redox kinetics in ceria: exploration of the transition from gas-phase to material-kinetic limitations.

PubMed

Ji, Ho-Il; Davenport, Timothy C; Gopal, Chirranjeevi Balaji; Haile, Sossina M

2016-08-03

The redox kinetics of undoped ceria (CeO2-δ) are investigated by the electrical conductivity relaxation method in the oxygen partial pressure range of -4.3 ≤ log(pO2/atm) ≤ -2.0 at 1400 °C. It is demonstrated that extremely large gas flow rates, relative to the mass of the oxide, are required in order to overcome gas phase limitations and access the material kinetic properties. Using these high flow rate conditions, the surface reaction rate constant kchem is found to obey the correlation log(kchem/cm s(-1)) = (0.84 ± 0.02) × log(pO2/atm) - (0.99 ± 0.05) and increases with oxygen partial pressure. This increase contrasts the known behavior of the dominant defect species, oxygen vacancies and free electrons, which decrease in concentration with increasing oxygen partial pressure. For the sample geometries employed, diffusion was too fast to be detected. At low gas flow rates, the relaxation process becomes limited by the capacity of the sweep gas to supply/remove oxygen to/from the oxide. An analytical expression is derived for the relaxation in the gas-phase limited regime, and the result reveals an exponential decay profile, identical in form to that known for a surface reaction limited process. Thus, measurements under varied gas flow rates are required to differentiate between surface reaction limited and gas flow limited behavior.

Alloy catalysts with monolith supports for methanation of coal-derived gases. Quarterly technical progress report, September 21-December 20, 1979

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartholomew, C.H.

1980-01-05

Tests for catalyst deactivation by carbon deposition in a Berty reactor showed that CO partial pressure exerted a greater influence on deactivation than H/sub 2/ partial pressure. In kinetic studies in which H/sub 2/O vapor was added to the reactant gases, H/sub 2/O was found to inhibit the methanation reaction. H/sub 2/O inhibition was found to increase with temperature and loss of activity was observed at H/sub 2/O/CO ratios greater than one. The order of methanation with respect to H/sub 2/ and CO varies over the range of temperature from 498 to 598/sup 0/K. Rate data indicate a change inmore » mechanism or rate determining step at higher temperatures. Our experience with a quartz CFSTR has shown that this reactor is very delicate and needs near constant attention to maintain proper working order.« less

Solubility of hydrogen sulfide in aqueous mixtures of monoethanolamine with N-methyldiethanolamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng Hui Li; Keh Perng Shen

1993-01-01

Alkanolamine aqueous solutions are frequently used for the removal of acidic gases, such as CO[sub 2] and H[sub 2]S, from gas streams in the natural gas and synthetic ammonia industries and petroleum chemical plants. The solubilities of hydrogen sulfide in aqueous mixtures of monoethanolamine (MEA) with N-methyl-diethanolamine (MDEA) have been measured at 40, 60, 80, and 100C and at partial pressures of hydrogen sulfide ranging from 1.0 to 450 kPa. The mixtures of alkanolamines studied are 4.95 kmol/m[sup 3] MEA, 3.97 kmol/m[sup 3] MEA + 0.51 kmol/m[sup 3] MDEA, 2.0 kmol/m[sup 3] MEA + 1.54 kmol/m[sup 3] MDEA, and 2.57more » kmol/m[sup 3] MDEA aqueous solutions. The solubilities of hydrogen sulfide in aqueous alkanolamine solutions are reported as functions of the partial pressure of hydrogen sulfide at the temperatures of 40-100C.« less

Post-combustion CO2 capture with activated carbons using fixed bed adsorption

NASA Astrophysics Data System (ADS)

Al Mesfer, Mohammed K.; Danish, Mohd; Fahmy, Yasser M.; Rashid, Md. Mamoon

2018-03-01

In the current work, the capturing of carbon dioxide from flue gases of post combustion emission using fixed bed adsorption has been carried out. Two grades of commercial activated carbon (sorbent-1 and sorbent-2) were used as adsorbent. Feed consisting of CO2 and N2 mixture was used for carrying out the adsorption. The influence of bed temperature, feed rate, equilibrium partial pressure and initial % CO2 in feed were considered for analyzing adsorption-desorption process. It was found that the total adsorption-desorption cycle time decreases with increased column temperature and feed rates. The time required to achieve the condition of bed saturation decreases with increased bed temperature and feed rates. The amount of CO2 adsorbed/Kg of the adsorbent declines with increased bed temperature with in studied range for sorbent-1 and sorbent-2. It was suggested that the adsorption capacity of the both the sorbents increases with increased partial pressure of the gas.

Turbulent flow in a partially filled pipe

NASA Astrophysics Data System (ADS)

Ng, Henry; Cregan, Hope; Dodds, Jonathan; Poole, Robert; Dennis, David

2017-11-01

Turbulent flow in a pressure driven pipe running partially full has been investigated using high-speed 2D-3C Stereoscopic Particle Imaging Velocimetry. With the field-of-view spanning the entire pipe cross section we are able to reconstruct the full three dimensional quasi-instantaneous flow field by invoking Taylor's hypothesis. The measurements were carried out over a range of flow depths at a constant Reynolds number based on hydraulic diameter and bulk velocity of Re = 32 , 000 . In agreement with previous studies, the ``velocity dip'' phenomenon, whereby the location of the maximum streamwise velocity occurs below the free surface was observed. A mean flow secondary current is observed near the free surface with each of the counter-rotating rollers filling the half-width of the pipe. Unlike fully turbulent flow in a rectangular open channel or pressurized square duct flow where the secondary flow cells appear in pairs about a corner bisector, the mean secondary motion observed here manifests only as a single pair of vortices mirrored about the pipe vertical centreline.

Growth responses of Neurospora crassa to increased partial pressures of the noble gases and nitrogen.

PubMed

Buchheit, R G; Schreiner, H R; Doebbler, G F

1966-02-01

Buchheit, R. G. (Union Carbide Corp., Tonawanda, N.Y.), H. R. Schreiner, and G. F. Doebbler. Growth responses of Neurospora crassa to increased partial pressures of the noble gases and nitrogen. J. Bacteriol. 91:622-627. 1966.-Growth rate of the fungus Neurospora crassa depends in part on the nature of metabolically "inert gas" present in its environment. At high partial pressures, the noble gas elements (helium, neon, argon, krypton, and xenon) inhibit growth in the order: Xe > Kr> Ar > Ne > He. Nitrogen (N(2)) closely resembles He in inhibitory effectiveness. Partial pressures required for 50% inhibition of growth were: Xe (0.8 atm), Kr (1.6 atm), Ar (3.8 atm), Ne (35 atm), and He ( approximately 300 atm). With respect to inhibition of growth, the noble gases and N(2) differ qualitatively and quantitatively from the order of effectiveness found with other biological effects, i.e., narcosis, inhibition of insect development, depression of O(2)-dependent radiation sensitivity, and effects on tissue-slice glycolysis and respiration. Partial pressures giving 50% inhibition of N. crassa growth parallel various physical properties (i.e., solubilities, solubility ratios, etc.) of the noble gases. Linear correlation of 50% inhibition pressures to the polarizability and of the logarithm of pressure to the first and second ionization potentials suggests the involvement of weak intermolecular interactions or charge-transfer in the biological activity of the noble gases.

Sulfuric Acid Monohydrate: Formation and Heterogeneous Chemistry in the Stratosphere

NASA Technical Reports Server (NTRS)

Zhang, Renyi; Leu, Ming-Taun; Keyser, Leon F.

1995-01-01

We have investigated some thermodynamic properties (i.e., freezing/melting points) and heterogeneous chemistry of sulfuric acid monohydrate (SAM, H2SO4.H2O), using a fast flow reactor coupled to a quadrupole mass spectrometer. The freezing point observations of thin liquid sulfuric acid films show that for acid contents between 75 and 85 wt % the monohydrate crystallizes readily at temperatures between 220 and 240 K on a glass substrate. Once formed, SAM can be thermodynamically stable in the H2O partial pressure range of (1-4) x 10(exp -4) torr and in the temperature range of 220-240 K. For a constant H2O partial pressure, lowering the temperature causes SAM to melt when the temperature and water partial pressure conditions are out of its stability regime. The reaction probability measurements indicate that the hydrolysis of N2O5 is significantly suppressed owing to the formation of crystalline SAM: The reaction probability on water-rich SAM (with higher relative humidity, or RH) is of the order of 10(exp -3) at 210 K and decreases by more than an order of magnitude for the acid-rich form (with lower RH). The hydrolysis rate of ClONO2 on water-rich SAM is even smaller, of the order of 10(exp -4) at 195 K. These reported values on crystalline SAM are much smaller than those on liquid solutions. No enhancement of these reactions is observed in the presence of HCl vapor at the stratospheric concentrations. In addition, Brunauer, Emmett, and Teller analysis of gas adsorption isotherms and photomicrography have been performed to characterize the surface roughness and porosities of the SAM substrate. The results suggest the possible formation of SAM in some regions of the middle- or low-latitude stratosphere and, consequently, much slower heterogeneous reactions on the frozen aerosols.

High-temperature mass spectrometric study of the vaporization processes and thermodynamic properties of melts in the PbO-B2O3-SiO2 system.

PubMed

Stolyarova, V L; Lopatin, S I; Shilov, A L; Shugurov, S M

2013-07-15

The unique properties of the PbO-B2O3-SiO2 system, especially its extensive range of glass-forming compositions, make it valuable for various practical applications. The thermodynamic properties and vaporization of PbO-B2O3-SiO2 melts are not well established so far and the data obtained on these will be useful for optimization of technology and thermodynamic modeling of glasses. High-temperature Knudsen effusion mass spectrometry was used to study vaporization processes and to determine the partial pressures of components of the PbO-B2O3-SiO2 melts. Measurements were performed with a MS-1301 mass spectrometer. Vaporization was carried out using two quartz effusion cells containing the sample under study and pure PbO (reference substance). Ions were produced by electron ionization at an energy of 25 eV. To facilitate interpretation of the mass spectra, the appearance energies of ions were also measured. Pb, PbO and O2 were found to be the main vapor species over the samples studied at 1100 K. The PbO activities as a function of the composition of the system were derived from the measured PbO partial pressures. The B2O3 and SiO2 activities, the Gibbs energy of formation, the excess Gibbs energy of formation and mass losses in the samples studied were calculated. Partial pressures of the vapor species over PbO-B2O3-SiO2 melts were measured at 1100 K in the wide range of compositions using the Knudsen mass spectrometric method. The data enabled the PbO, B2O3, and SiO2 activities in these melts to be derived and provided evidence of their negative deviations from ideal behavior. Copyright © 2013 John Wiley & Sons, Ltd.

A System for Incubations at High Gas Partial Pressure

PubMed Central

Sauer, Patrick; Glombitza, Clemens; Kallmeyer, Jens

2012-01-01

High-pressure is a key feature of deep subsurface environments. High partial pressure of dissolved gasses plays an important role in microbial metabolism, because thermodynamic feasibility of many reactions depends on the concentration of reactants. For gases, this is controlled by their partial pressure, which can exceed 1 MPa at in situ conditions. Therefore, high hydrostatic pressure alone is not sufficient to recreate true deep subsurface in situ conditions, but the partial pressure of dissolved gasses has to be controlled as well. We developed an incubation system that allows for incubations at hydrostatic pressure up to 60 MPa, temperatures up to 120°C, and at high gas partial pressure. The composition and partial pressure of gasses can be manipulated during the experiment. To keep costs low, the system is mainly made from off-the-shelf components with only very few custom-made parts. A flexible and inert PVDF (polyvinylidene fluoride) incubator sleeve, which is almost impermeable for gases, holds the sample and separates it from the pressure fluid. The flexibility of the incubator sleeve allows for sub-sampling of the medium without loss of pressure. Experiments can be run in both static and flow-through mode. The incubation system described here is usable for versatile purposes, not only the incubation of microorganisms and determination of growth rates, but also for chemical degradation or extraction experiments under high gas saturation, e.g., fluid–gas–rock-interactions in relation to carbon dioxide sequestration. As an application of the system we extracted organic compounds from sub-bituminous coal using H2O as well as a H2O–CO2 mixture at elevated temperature (90°C) and pressure (5 MPa). Subsamples were taken at different time points during the incubation and analyzed by ion chromatography. Furthermore we demonstrated the applicability of the system for studies of microbial activity, using samples from the Isis mud volcano. We could detect an increase in sulfate reduction rate upon the addition of methane to the sample. PMID:22347218

Thermal Equation of State of TiC: A Synchrotron X-ray Diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, X.; Lin, Z; Zhang, J

2010-01-01

The pressure-volume-temperature measurements were carried out for titanium carbide (TiC) at pressures and temperatures up to 8.1 GPa and 1273 K using energy-dispersive synchrotron x-ray diffraction. Thermoelastic parameters were derived for TiC based on a modified high-temperature Birch-Murnaghan equation of state and a thermal pressure approach. With the pressure derivative of the bulk modulus, K{prime}{sub 0}, fixed at 4.0, we obtain: the ambient bulk modulus K{sub 0} = 268(6) GPa, which is comparable to previously reported value; temperature derivative of bulk modulus at constant pressure ({partial_derivative}K{sub T}/{partial_derivative}T){sub P} = -0.026(9) GPa K{sup -1}, volumetric thermal expansivity {alpha}{sub T}(K{sup -1}) =more » a+b T with a = 1.62(12) x 10{sup -5} K{sup -1} and b = 1.07(17) x 10{sup -8}K{sup -2}, pressure derivative of thermal expansion ({partial_derivative}{sub {alpha}}/{partial_derivative}{sub P}){sub T} = (-3.62 {+-} 1.14) x 10{sup -7} GPa{sup -1} K{sup -1}, and temperature derivative of bulk modulus at constant volume ({partial_derivative}K{sub T}/{partial_derivative}T){sub V} = -0.015(8) GPa K{sup -1}. These results provide fundamental thermophysical properties for TiC for the first time and are important to theoretical and computational modeling of transition metal carbides.« less

Partial phase diagram for the system NH3-H2O - The water-rich region

NASA Technical Reports Server (NTRS)

Johnson, M. L.; Schwake, A.; Nicol, M.

1984-01-01

Phase boundaries of the H2O-NH3 system for (NH3)/x/(H2O)/1-x/ have been determined with diamond-anvil cells for mixtures in two composition ranges: (1) for x in the range from 0 to 0.3, at pressures up to 4 GPa at 21 C, and (2) for x in the range from 0.46 to 0.50, at pressures up to 5 GPa from 150 to 400 K. Phases were identified visually with a microscope and polarized optics. The NH3.2(H2O) phase is strongly anisotropic with a much smaller refractive index than that of ice VII and cracks in two nonperpendicular networks. NH3.H2O has a refractive index closer to that of Ice VII and does not appear to form cracks. Both phases are colorless. Phase boundaries were determined on both increasing and decreasing pressures, and compositions of the ammonia ices were determined by estimating relative amounts of water and ammonia ices at known overall compositions. For low-ammonia compositions (x equal to or less than 0.15), the following assemblages succedd one another as pressure increases: liquid; liquid and Ice VI (at 1.0 + GPa); liquid and Ice VII (at 2.1 GPa); Ice VII and NH3.H2O (at 3.5 GPa). For x in the range from 0.15 to 0.30, the water ice and liquid fields are replaced by the NH3.2(H2O) and liquid field at pressures down to 1.0 GPa and lower.

Spatial Characteristics of F/A-18 Vertical Tail Buffet Pressures Measured in Flight

NASA Technical Reports Server (NTRS)

Moses, Robert W.; Shah, Gautam H.

1998-01-01

Buffeting is an aeroelastic phenomenon which plagues high performance aircraft, especially those with twin vertical tails, at high angles of attack. Previous wind-tunnel and flight tests were conducted to characterize the buffet loads on the vertical tails by measuring surface pressures, bending moments, and accelerations. Following these tests, buffeting estimates were computed using the measured buffet pressures and compared to the measured responses. The estimates did not match the measured data because the assumed spatial correlation of the buffet pressures was not correct. A better understanding of the partial (spatial) correlation of the differential buffet pressures on the tail was necessary to improve the buffeting estimates. Several wind-tunnel investigations were conducted for this purpose. When combined and compared, the results of these tests show that the partial correlation depends on and scales with flight conditions. One of the remaining questions is whether the windtunnel data is consistent with flight data. Presented herein, cross-spectra and coherence functions calculated from pressures that were measured on the high alpha research vehicle (HARV) indicate that the partial correlation of the buffet pressures in flight agrees with the partial correlation observed in the wind tunnel.

Correlation of Fin Buffet Pressures on an F/A-18 with Scaled Wind-Tunnel Measurements

NASA Technical Reports Server (NTRS)

Moses, Robert W.; Shah, Gautam H.

1999-01-01

Buffeting is an aeroelastic phenomenon occurring at high angles of attack that plagues high performance aircraft, especially those with twin vertical tails. Previous wind-tunnel and flight tests were conducted to characterize the buffet loads on the vertical tails by measuring surface pressures, bending moments, and accelerations. Following these tests, buffeting responses were computed using the measured buffet pressures and compared to the measured buffeting responses. The calculated results did not match the measured data because the assumed spatial correlation of the buffet pressures was not correct. A better understanding of the partial (spatial) correlation of the differential buffet pressures on the tail was necessary to improve the buffeting predictions. Several wind-tunnel investigations were conducted for this purpose. When compared, the results of these tests show that the partial correlation scales with flight conditions. One of the remaining questions is whether the wind-tunnel data is consistent with flight data. Presented herein, cross-spectra and coherence functions calculated from pressures that were measured on the High Alpha Research Vehicle indicate that the partial correlation of the buffet pressures in flight agrees with the partial correlation observed in the wind tunnel.

Effect of pressure on the Raman-active modes of zircon (ZrSiO4): a first-principles study

NASA Astrophysics Data System (ADS)

Sheremetyeva, Natalya; Cherniak, Daniele J.; Watson, E. Bruce; Meunier, Vincent

2018-02-01

Density-functional theory (DFT) was employed in a first-principles study of the effects of pressure on the Raman-active modes of zircon (ZrSiO4), using both the generalized gradient and local density approximations (GGA and LDA, respectively). Beginning with the equilibrium structure at zero pressure, we conducted a calibration of the effect of pressure in a manner procedurally similar to an experimental calibration. For pressures between 0 and 7 GPa, we find excellent qualitative agreement of frequency-pressure slopes partial ω /partial P calculated from GGA DFT with results of previous experimental studies. In addition, we were able to rationalize the ω vs. P behavior based on details of the vibrational modes and their atomic displacements. Most of the partial ω /partial P slopes are positive as expected, but the symmetry of the zircon lattice also results in two negative slopes for modes that involve slight shearing and rigid rotation of SiO4 tetrahedra. Overall, LDA yields absolute values of the frequencies of the Raman-active modes in good agreement with experimental values, while GGA reproduces the shift in frequency with pressure especially well.

Oxidation kinetics of a continuous carbon phase in a nonreactive matrix

NASA Technical Reports Server (NTRS)

Eckel, Andrew J.; Cawley, James D.; Parthasarathy, Triplicane A.

1995-01-01

Analytical solutions of and experimental results on the oxidation kinetics of carbon in a pore are presented. Reaction rate, reaction sequence, oxidant partial pressure, total system pressure, pore/crack dimensions, and temperature are analyzed with respect to the influence of each on an overall linear-parabolic rate relationship. Direct measurement of carbon recession is performed using two microcomposite model systems oxidized in the temperature range of 700 to 1200 C, and for times to 35 h. Experimental results are evaluated using the derived analytical solutions. Implications on the oxidation resistance of continuous-fiber-reinforced ceramic-matrix composites containing a carbon constituent are discussed.

Experimental petrology and origin of Fra Mauro rocks and soil

NASA Technical Reports Server (NTRS)

Walker, D.; Longhi, J.; Hays, J. F.

1972-01-01

Melting experiments over the pressure range 0 to 20 kilobars were conducted on Apollo 14 igneous rocks 14310 and 14072 and on comprehensive fines 14259. The mineralogy and textures of rocks 14310 and 14072 are presumed to be the result of near-surface crystallization. The chemical compositions of the samples show special relationships to multiply-saturated liquids in the system: anorthite-forsterite-fayalite-silica at low pressure. Partial melting of a lunar crust consisting largely of plagioclase, low calcium pyroxene, and olivine, followed by crystal fractionation at the lunar surface is proposed as a mechanism for the production of the igneous rocks and soil glasses sampled by Apollo 14.

Growth of the microalgae Neochloris oleoabundans at high partial oxygen pressures and sub-saturating light intensity.

PubMed

Sousa, Cláudia; de Winter, Lenneke; Janssen, Marcel; Vermuë, Marian H; Wijffels, René H

2012-01-01

The effect of partial oxygen pressure on growth of Neochloris oleoabundans was studied at sub-saturating light intensity in a fully-controlled stirred tank photobioreactor. At the three partial oxygen pressures tested (P(O)₂= 0.24; 0.63; 0.84 bar), the specific growth rate was 1.38; 1.36 and 1.06 day(-1), respectively. An increase of the P(CO)₂from 0.007 to 0.02 bar at P(O₂) of 0.84 bar resulted in an increase in the growth rate from 1.06 to 1.36 day(-1). These results confirm that the reduction of algal growth at high oxygen concentrations at sub-saturating light conditions is mainly caused by competitive inhibition of Rubisco. This negative effect on growth can be overcome by restoring the O(2)/CO(2) ratio by an increase in the partial carbon dioxide pressure. In comparison to general practice (P(O(2)) = 0.42 bar), working at partial O(2) pressure of 0.84 bar could reduce the energy requirement for degassing by a factor of 3-4. Copyright © 2011 Elsevier Ltd. All rights reserved.

Decline in arterial partial pressure of oxygen after exercise: a surrogate marker of pulmonary vascular obstructive disease in patients with atrial septal defect and severe pulmonary hypertension.

PubMed

Laksmivenkateshiah, Srinivas; Singhi, Anil K; Vaidyanathan, Balu; Francis, Edwin; Karimassery, Sundaram R; Kumar, Raman K

2011-06-01

To examine the utility of decline in arterial partial pressure of oxygen after exercise as a marker of pulmonary vascular obstructive disease in patients with atrial septal defect and pulmonary hypertension. Treadmill exercise was performed in 18 patients with atrial septal defect and pulmonary hypertension. Arterial blood gas samples were obtained before and after peak exercise. A decline in the arterial pressure of oxygen of more than 10 millimetres of mercury after exercise was considered significant based on preliminary tests conducted on the controls. Cardiac catheterisation was performed in all patients and haemodynamic data sets were obtained on room air, oxygen, and a mixture of oxygen and nitric oxide (30-40 parts per million). There were 10 patients who had more than a 10 millimetres of mercury drop in arterial partial pressure of oxygen after exercise and who had a basal pulmonary vascular resistance index of more than 7 Wood units per square metre. Out of eight patients who had less than a 10 millimetres of mercury drop in arterial partial pressure of oxygen after exercise, seven had a basal pulmonary vascular resistance index of less than 7 Wood units per square metre, p equals 0.0001. A decline in arterial partial pressure of oxygen of more than 10 millimetres of mercury predicted a basal pulmonary vascular resistance index of more than 7 Wood units per square metre with a specificity of 100% and a sensitivity of 90%. A decline in arterial partial pressure of oxygen following exercise appears to predict a high pulmonary vascular resistance index in patients with atrial septal defect and pulmonary hypertension. This test is a useful non-invasive marker of pulmonary vascular obstructive disease in this subset.

Subatmospheric vapor pressures for fluoromethane (R41), 1,1-difluoroethane (R152a), and 1,1,1-trifluoroethane (R143a) evaluated from internal-energy measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duarte-Garza, H.A.; Magee, J.W.

1999-09-01

Vapor pressures were evaluated from measured internal-energy changes {Delta}U{sup (2)} in the vapor + liquid two-phase region. The method employed a thermodynamic relationship between the derivative quantity ({partial_derivative}U{sup (2)}/{partial_derivative}V){sub T}, the vapor pressure p{sub {sigma}}, and its temperature derivative ({partial_derivative}p/{partial_derivative}T){sub {sigma}}. This method was applied at temperatures between the triple point and the normal boiling point of three substances: fluoromethane (R41), 1,1-difluoroethane (R152a), and 1,1,1-trifluoroethane (R143a). In the case of R41, vapor pressures up to 1 MPa were calculated to validate the technique at higher pressures. For R152a, the calculated vapor pressure at the triple-point temperature differed from a directmore » experimental measurement by less than the claimed uncertainty (5 Pa) of the measurement. The calculated vapor pressures for R41 helped to resolve discrepancies in several published vapor pressure sources. Agreement with experimentally measured vapor pressures for R152a and for R143a near the normal boiling point (101.325 kPa) was within the experimental uncertainty of approximately 0.04 kPa (0.04%) for the published measurements.« less

Effect of partial meniscectomy at the medial posterior horn on tibiofemoral contact mechanics and meniscal hoop strains in human knees.

PubMed

Seitz, Andreas Martin; Lubomierski, Anja; Friemert, Benedikt; Ignatius, Anita; Dürselen, Lutz

2012-06-01

We examined the influence of partial meniscectomy of 10 mm width on 10 human cadaveric knee joints, as it is performed during the treatment of radial tears in the posterior horn of the medial meniscus, on maximum contact pressure, contact area (CA), and meniscal hoop strain in the lateral and medial knee compartments. In case of 0° and 30° flexion angle, 20% and 50% partial meniscectomy did not influence maximum contact pressure and area. Only in case of 60° knee flexion, 50% partial resection increased medial maximum contact pressure and decreased the medial CA statistically significant. However, 100% partial resection increased maximum contact pressure and decreased CA significantly in the meniscectomized medial knee compartment in all tested knee positions. No significant differences were noted for meniscal hoop strain. From a biomechanical point of view, our in vitro study suggests that the medial joint compartment is not in danger of accelerated cartilage degeneration up to a resection limit of 20% meniscal depth and 10 mm width. Contact mechanics are likely to be more sensitive to partial meniscectomy at higher flexion angles, which has to be further investigated. Copyright © 2011 Orthopaedic Research Society.

Impact of plunging breaking waves on a partially submerged cube

NASA Astrophysics Data System (ADS)

Wang, A.; Ikeda, C.; Duncan, J. H.

2013-11-01

The impact of a deep-water plunging breaking wave on a partially submerged cube is studied experimentally in a tank that is 14.8 m long and 1.2 m wide with a water depth of 0.91 m. The breakers are created from dispersively focused wave packets generated by a programmable wave maker. The water surface profile in the vertical center plane of the cube is measured using a cinematic laser-induced fluorescence technique with movie frame rates ranging from 300 to 4,500 Hz. The pressure distribution on the front face of the cube is measured with 24 fast-response sensors simultaneously with the wave profile measurements. The cube is positioned vertically at three heights relative to the mean water level and horizontally at a distance from the wave maker where a strong vertical water jet is formed. The portion of the water surface between the contact point on the front face of the cube and the wave crest is fitted with a circular arc and the radius and vertical position of the fitted circle is tracked during the impact. The vertical acceleration of the contact point reaches more than 50 times the acceleration of gravity and the pressure distribution just below the free surface shows a localized high-pressure region with a very high vertical pressure gradient. This work is supported by the Office of Naval Research under grant N000141110095.

Point Defect Structure of Cr203

DTIC Science & Technology

1987-10-01

Calculation of Electron Hole Mobility ........................ 104 6.2.3 Construction of the Defect Concentration vs. Oxygen Pressure Diagram...1000’ to 16000C ............ 123 7.7 Calculated diffusion coefficient vs. oxygen partial pressure diagram for pure Cr203 at 1100 0 C...127 7.10 Calculated parabolic rate constant vs. oxygen partial pressure diagram for pure Cr203 at

Growth Responses of Neurospora crassa to Increased Partial Pressures of the Noble Gases and Nitrogen

PubMed Central

Buchheit, R. G.; Schreiner, H. R.; Doebbler, G. F.

1966-01-01

Buchheit, R. G. (Union Carbide Corp., Tonawanda, N.Y.), H. R. Schreiner, and G. F. Doebbler. Growth responses of Neurospora crassa to increased partial pressures of the noble gases and nitrogen. J. Bacteriol. 91:622–627. 1966.—Growth rate of the fungus Neurospora crassa depends in part on the nature of metabolically “inert gas” present in its environment. At high partial pressures, the noble gas elements (helium, neon, argon, krypton, and xenon) inhibit growth in the order: Xe > Kr> Ar ≫ Ne ≫ He. Nitrogen (N2) closely resembles He in inhibitory effectiveness. Partial pressures required for 50% inhibition of growth were: Xe (0.8 atm), Kr (1.6 atm), Ar (3.8 atm), Ne (35 atm), and He (∼ 300 atm). With respect to inhibition of growth, the noble gases and N2 differ qualitatively and quantitatively from the order of effectiveness found with other biological effects, i.e., narcosis, inhibition of insect development, depression of O2-dependent radiation sensitivity, and effects on tissue-slice glycolysis and respiration. Partial pressures giving 50% inhibition of N. crassa growth parallel various physical properties (i.e., solubilities, solubility ratios, etc.) of the noble gases. Linear correlation of 50% inhibition pressures to the polarizability and of the logarithm of pressure to the first and second ionization potentials suggests the involvement of weak intermolecular interactions or charge-transfer in the biological activity of the noble gases. PMID:5883104

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

NASA Technical Reports Server (NTRS)

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

1973-01-01

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

Fiber Optic Sensor for Acoustic Detection of Partial Discharges in Oil-Paper Insulated Electrical Systems

PubMed Central

Posada-Roman, Julio; Garcia-Souto, Jose A.; Rubio-Serrano, Jesus

2012-01-01

A fiber optic interferometric sensor with an intrinsic transducer along a length of the fiber is presented for ultrasound measurements of the acoustic emission from partial discharges inside oil-filled power apparatus. The sensor is designed for high sensitivity measurements in a harsh electromagnetic field environment, with wide temperature changes and immersion in oil. It allows enough sensitivity for the application, for which the acoustic pressure is in the range of units of Pa at a frequency of 150 kHz. In addition, the accessibility to the sensing region is guaranteed by immune fiber-optic cables and the optical phase sensor output. The sensor design is a compact and rugged coil of fiber. In addition to a complete calibration, the in-situ results show that two types of partial discharges are measured through their acoustic emissions with the sensor immersed in oil. PMID:22666058

Fatigue crack growth in 7475-T651 aluminum alloy plate in hard vacuum and water vapor. M.S. Thesis - George Washington Univ.

NASA Technical Reports Server (NTRS)

Dicus, D. L.

1981-01-01

Compact specimens of 25 mm thick aluminum alloy plate were subjected to constant amplitude fatigue testing at a load ratio of 0.2. Crack growth rates were determined at frequencies of 1 Hz and 10 Hz in hard vacuum and laboratory air, and in mixtures of water vapor and nitrogen at water vapor partial pressures ranging from 94 Pa to 3.8 kPa. A significant effect of water vapor on fatigue crack growth rates was observed at the lowest water vapor pressure tested. Crack rates changed little for pressures up to 1.03 kPa, but abruptly accelerated at higher pressures. At low stress intensity factor ranges, cracking rates at the lowest and highest water vapor pressure tested were, respectively, two and five times higher than rates in vacuum. Although a frequency was observed in laboratory air, cracking rates in water vapor and vacuum are insensitive to a ten-fold change in frequency. Surfaces of specimens tested in water vapor and vacuum exhibited different amounts of residual deformation. Reduced deformation on the fracture surfaces of the specimens tested in water vapor suggests embrittlement of the plastic zone ahead of the crack tip as a result of environmental interaction.

Multi-species sensing using multi-mode absorption spectroscopy with mid-infrared interband cascade lasers

NASA Astrophysics Data System (ADS)

O'Hagan, S.; Northern, J. H.; Gras, B.; Ewart, P.; Kim, C. S.; Kim, M.; Merritt, C. D.; Bewley, W. W.; Canedy, C. L.; Vurgaftman, I.; Meyer, J. R.

2016-06-01

The application of an interband cascade laser, ICL, to multi-mode absorption spectroscopy, MUMAS, in the mid-infrared region is reported. Measurements of individual mode linewidths of the ICL, derived from the pressure dependence of lineshapes in MUMAS signatures of single, isolated, lines in the spectrum of HCl, were found to be in the range 10-80 MHz. Multi-line spectra of methane were recorded using spectrally limited bandwidths, of approximate width 27 cm-1, defined by an interference filter, and consist of approximately 80 modes at spectral locations spanning the 100 cm-1 bandwidth of the ICL output. Calibration of the methane pressures derived from MUMAS data using a capacitance manometer provided measurements with an uncertainty of 1.1 %. Multi-species sensing is demonstrated by the simultaneous detection of methane, acetylene and formaldehyde in a gas mixture. Individual partial pressures of the three gases are derived from best fits of model MUMAS signatures to the data with an experimental error of 10 %. Using an ICL, with an inter-mode interval of ~10 GHz, MUMAS spectra were recorded at pressures in the range 1-10 mbar, and, based on the data, a potential minimum detection limit of the order of 100 ppmv is estimated for MUMAS at atmospheric pressure using an inter-mode interval of 80 GHz.

Effect of high hydrostatic pressure on the supramolecular structure of corn starch with different amylose contents.

PubMed

Yang, Zhi; Swedlund, Peter; Hemar, Yacine; Mo, Guang; Wei, Yanru; Li, Zhihong; Wu, Zhonghua

2016-04-01

Corn starches with amylose contents ranging from 0 to 80% were suspended in 60 wt% water or ethanol and subjected to high hydrostatic pressure (HHP) up to 600 MPa. The impact of HHP treatment on the granule morphology, lamellae structures, and crystalline characteristics were examined with a combination of SAXS, WAXS and optical microscopy. All starch dispersed in water showed a decrease in area of the lamellar peak in the SAXS data at q∼0.6 nm(-1). The lamellae thickness (d) increased for pressurized waxy, normal, and Gelose80 corn starches, suggesting water is forced into starch lamellae during HHP. However, for Gelose50 corn starch, the d remained constant over the whole pressure range and light microscopy showed no obvious granule swelling. WAXS studies demonstrated that HHP partially converted A-type starches (waxy and normal corn) to starches with a faint B-type pattern while starches with a B+V-type pattern (Gelose50 and Gelose80), were not affected by HHP. All corn starches suspended in ethanol showed no detectable changes in either granule morphology, or the fractal, the lamellae, and the crystalline structures. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of water vapor on fatigue crack growth in 7475-T651 aluminum alloy plate. [for aerospace applications

NASA Technical Reports Server (NTRS)

Dicus, D. L.

1984-01-01

The effects of water vapor on fatigue crack growth in 7475-T651 aluminum alloy plate at frequencies of 1 Hz and 10 Hz were investigated. Twenty-five mm thick compact specimens were subjected to constant amplitude fatigue testing at a load ratio of 0.2. Fatigue crack growth rates were calculated from effective crack lengths determined using a compliance method. Tests were conducted in hard vacuum and at water vapor partial pressures ranging from 94 Pa to 3.8 kPa. Fatigue crack growth rates were frequency insensitive under all environment conditions tested. For constant stress intensity factor ranges crack growth rate transitions occurred at low and high water vapor pressures. Crack growth rates at intermediate pressures were relatively constant and showed reasonable agreement with published data for two Al-Cu-Mg alloys. The existence of two crack growth rate transitions suggests either a change in rate controlling kinetics or a change in corrosion fatigue mechanism as a function of water vapor pressure. Reduced residual deformation and transverse cracking specimens tested in water vapor versus vacuum may be evidence of embrittlement within the plastic zone due to environmental interaction.

The effect of water vapor on fatigue crack Growth in 7475-t651 aluminum alloy plate. [for aerospace applications

NASA Technical Reports Server (NTRS)

Dicus, D. L.

1982-01-01

The effects of water vapor on fatigue crack growth in 7475-T651 aluminum alloy plate at frequencies of 1 Hz and 10 Hz were investigated. Twenty-five mm thick compact specimens were subjected to constant amplitude fatigue testing at a load ratio of 0.2. Fatigue crack growth rates were calculated from effective crack lengths determined using a compliance method. Tests were conducted in hard vacuum and at water vapor partial pressures ranging from 94 Pa to 3.8 kPa. Fatigue crack growth rates were frequency insensitive under all environment conditions tested. For constant stress intensity factor ranges crack growth rate transitions occurred at low and high water vapor pressures. Crack growth rates at intermediate pressures were relatively constant and showed reasonable agreement with published data for two Al-Cu-Mg alloys. The existence of two crack growth rate transitions suggests either a change in rate controlling kinetics or a change in corrosion fatigue mechanism as a function of water vapor pressure. Reduced residual deformation and transverse cracking specimens tested in water vapor versus vacuum may be evidence of embrittlement within the plastic zone due to environmental interaction.

Influence of oxygen partial pressure on the composition and orientation of strontium-doped lead zirconate titanate thin films.

PubMed

Sriram, S; Bhaskaran, M; du Plessis, J; Short, K T; Sivan, V P; Holland, A S

2009-01-01

The influence of oxygen partial pressure during the deposition of piezoelectric strontium-doped lead zirconate titanate thin films is reported. The thin films have been deposited by RF magnetron sputtering in an atmosphere of high purity argon and oxygen (in the ratio of 9:1), on platinum-coated silicon substrates (heated to 650 degrees C). The influence of oxygen partial pressure is studied to understand the manner in which the stoichiometry of the thin films is modified, and to understand the influence of stoichiometry on the perovskite orientation. This article reports on the results obtained from films deposited at oxygen partial pressures of 1-5 mTorr. The thin films have been studied using a combination of X-ray photoelectron spectroscopy (XPS), glancing angle X-ray diffraction (GA-XRD), and atomic force microscopy (AFM). XPS analysis highlights the marked influence of variations in oxygen pressure during sputtering, observed by variations in oxygen concentration in the thin films, and in some cases by the undesirable decrease in lead concentration in the thin films. GA-XRD is used to study the relative variations in perovskite peak intensities, and has been used to determine the deposition conditions to attain the optimal combination of stoichiometry and orientation. AFM scans show the marked influence of the oxygen partial pressure on the film morphology.

Evaluation of a butorphanol, detomidine, and midazolam combination for immobilization of captive Nile lechwe antelopes (Kobus magaceros).

PubMed

Laricchiuta, Pietro; De Monte, Valentina; Campolo, Marco; Grano, Fabio; Iarussi, Fabrizio; Crovace, Antonio; Staffieri, Francesco

2012-07-01

Field immobilization of captive antelope may be required for medical examination, blood sample collection, and animal identification. The aim of this study was to evaluate the effects of a combination of butorphanol, detomidine, and midazolam (BDM) and its partial reversibility in Nile lechwe antelope (Kobus megaceros). Nine captive lechwes, weighing 28-64 kg, were immobilized, in February 2011, with butorphanol 0.20 ± 0.05 (mean ± SD) mg/kg, detomidine 0.20 ± 0.05 mg/kg, and midazolam 0.31 ± 0.08 mg/kg administered intramuscularly (IM) with a blowpipe. Physiologic parameters and depth of anesthesia were recorded when the animals became recumbent at 19.55 ± 8.36 min after darting (T0) and after 10 (T10), 20 (T20), and 30 (T30) min. An arterial blood sample was collected at T20. At the end of the procedures, immobilization was partially reversed with atipamezole 0.25 mg/kg IM. Quality of induction, immobilization, and recovery was scored. The BDM combination induced immobilization and lateral recumbency in 13.44 ± 5.61 min. Median induction score (scored 1 [excellent] to 4 [poor]) was 1 (range 1-2). Heart rate varied 40-104 beats/min, respiratory rate 16-108 breaths/min, and rectal temperature 36.5-40.3 C. Hyperthermia was observed and rapidly treated in three animals that demonstrated insufficient immobilization after darting. Arterial blood gas analyses revealed a mean pH of 7.43 ± 0.07, partial arterial pressure of CO(2) of 44.1 ± 6.0 mmHg, partial arterial pressure of O(2) of 74.0 ± 13.5 mmHg, and an arterial O(2) saturation of 94.77 ± 3.96%. Recovery was smooth and animals were walking in 13.44 ± 7.85 min. Median recovery score (1 = excellent to 4 = poor) was 1 (range 1-2). The BDM was effective in immobilizing captive healthy lechwes with minimal cardiorespiratory changes.

Effect of elimination of nitrogen and/or hypoxia or restricted visual environment on color vision and range of accommodation

NASA Technical Reports Server (NTRS)

Wolbarsht, M. L.; White, C. W.; Anderson, W. B., Jr.

1973-01-01

The effects upon range of accommodation and color vision of reduced atmospheric pressure, at partial and complete elimination of nitrogen, of hypoxia, and of exposure for varying periods of time to restricted visual environment, have been studied alone or in various combinations. Measurements were made on the electroretinogram, the electrooculogram, and the diameter of the retinal vessels as an indicator of blood flow to the retina at the time of total elimination of nitrogen. An objective method was used to test range of accommodation. In the color vision test the flicker colors of a Benham's top were matched with a colorimeter.

Measuring Ancient Air Pressure Using Fossilized Cyanobacteria

NASA Astrophysics Data System (ADS)

Silverman, S. N.; Som, S. M.; Gordon, R.; Bebout, B.

2016-12-01

The evolution of Earth's atmosphere has been governed by biological evolution. The dominant air component, nitrogen, has undergone substantial variation over geological time. Today, the partial pressure of nitrogen is 0.79 bar, but this value could have been much higher during early Earth1. The nitrogen partial pressure is postulated to have dropped to a maximum of 0.5 bar before the Great Oxidation Event 2.4 billion years ago, and subsequently recovered to the 0.8 bar value of our modern atmosphere over the next 330 million years2. We are placing constraints on the trajectory of this recovery by investigating how nitrogen partial pressure influences the morphology of a certain species of filamentous cyanobacteria that has been found fossilized in 2 billion year old rocks. These filamentous cyanobacteria convert nitrogen from its dissolved gaseous state (N2) to a biologically useful state (i.e. NH3) when the latter is present at growth-limiting concentrations in their aquatic environment. Such cyanobacteria develop heterocysts (specialized, visually distinct cells), which fix the nitrogen and laterally distribute it to neighboring cells along the one-dimensional filament. We suggest that the distance between heterocysts reflects the nitrogen partial pressure dissolved in water, which is related to atmospheric pN2 by Henry's law. In the laboratory, we are quantifying the relationship between heterocyst distance, variance and covariance to atmospheric pN2 by subjecting cyanobacteria (in media devoid of nitrate) to different partial pressures of N2 at a constant temperature and lighting for the representative species Anabaena variabilis. As far as we know, such experiments have not been previously conducted. This new geobarometer will complement existing methods of quantifying ancient nitrogen partial pressure. 1Goldblatt, Colin, et al. "Nitrogen-enhanced greenhouse warming on early Earth." Nature Geoscience 2 (2009): 891-896. 2Som, S., et al. "Earth's air pressure 2.7 billion years ago constrained to less than half of modern levels." Nature Geoscience 9 (2016): 448-451.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karabourniotis, D.; Couris, S.; Damelincourt, J.J.

The partial pressure of thallium in high-pressure Hg-TlI discharges with different mercury, thallium, and electron pressures has been measured by using the optically thin line Tl 655 nm and the self-reversed line Tl 535 nm. The partial pressure of the arc axis has been measured from the line Tl 655nm. The effective partial pressure has been measured from the self-reversed line Tl 535 nm on the basis of the multiparameter method, and it has been calculated from the known axis pressure of thallium and the calculation of its radial variation by taking into account the chemical reactions. The experimental resultsmore » confirm the dispersion character of the blue wing of the line Tl 535 nm. The systematic difference obtained between the measured and calculated effective pressure, particularly at the moment of minimum electron density, may be interpreted by deviations from the local thermodynamic equilibrium (LTE) caused by overpopulation of the upper level of the line Tl 535 nm.« less

Methods and apparatus for reducing corrosion in refractory linings

DOEpatents

Poeppel, Roger B.; Greenberg, Sherman; Diercks, Dwight R.

1987-01-01

Methods and apparatus are provided for reducing corrosion in a refractory lining of a liquid-containing vessel used in direct steelmaking processes. The vessel operates at between about 1600.degree. C. and about 1800.degree. C. and an oxygen partial pressure of about 10.sup.-12 atmospheres, creating slag which is rich in FeO. The refractory lining includes a significant level of chromium oxide (Cr.sub.2 O.sub.3), and has small interconnected pores which may be filled with a gas mixture having a higher total pressure and oxygen partial pressure than the total pressure and oxygen partial pressure associted with the liquid against the lining of the vessel. The gas mixture is forced through the pores of the lining so that the pores are continuously filled with the mixture. In this manner, the gas mixture creates a blanket which increases the oxygen partial pressure at the lining enough to maintain the chromium in the lining in a selected valence state in which the chromium has decreased solubility in the FeO slag, thereby reducing corrosion by the FeO and increasing the useful life of the refractory lining.

High-pressure applications in medicine and pharmacology

NASA Astrophysics Data System (ADS)

Silva, Jerson L.; Foguel, Debora; Suarez, Marisa; Gomes, Andre M. O.; Oliveira, Andréa C.

2004-04-01

High pressure has emerged as an important tool to tackle several problems in medicine and biotechnology. Misfolded proteins, aggregates and amyloids have been studied, which point toward the understanding of the protein misfolding diseases. High hydrostatic pressure (HHP) has also been used to dissociate non-amyloid aggregates and inclusion bodies. The diverse range of diseases that result from protein misfolding has made this theme an important research focus for pharmaceutical and biotech companies. The use of high pressure promises to contribute to identifying the mechanisms behind these defects and creating therapies against these diseases. High pressure has also been used to study viruses and other infectious agents for the purpose of sterilization and in the development of vaccines. Using pressure, we have detected the presence of a ribonucleoprotein intermediate, where the coat protein is partially unfolded but bound to RNA. These intermediates are potential targets for antiviral compounds. The ability of pressure to inactivate viruses, prions and bacteria has been evaluated with a view toward the applications of vaccine development and virus sterilization. Recent studies demonstrate that pressure causes virus inactivation while preserving the immunogenic properties. There is increasing evidence that a high-pressure cycle traps a virus in the 'fusion intermediate state', not infectious but highly immunogenic.

Incidence and Determinants of Port Occlusions in Cancer Outpatients: A Prospective Cohort Study.

PubMed

Milani, Alessandra; Mazzocco, Ketti; Gandini, Sara; Pravettoni, Gabriella; Libutti, Livio; Zencovich, Claudia; Sbriglia, Ada; Pari, Chiara; Magon, Giorgio; Saiani, Luisa

Normal saline is considered a safe alternative for heparin as a locking solution in totally implantable venous access devices. The incidence rate of partial occlusion with the use of normal saline (easy injection, impossible aspiration) is estimated at 4%. The aim of this study was to investigate determinants of partial occlusions with the use of normal saline solution and the maintenance of positive pressure in the catheter. We enrolled 218 patients with different solid tumors who underwent pharmacologic treatment through the port with different frequencies: from once every week to at least once every month. The port was flushed with normal saline solution keeping a positive pressure in the catheter. We performed 4111 observations and documented normal port functioning in 99% of observations (n = 4057) and partial occlusions in 1% of observations (n = 54). Partial occlusions were significantly associated with frequency of port flushing (P < .05), chemotherapy (P < .001), and blood sample collection (P < .001). The use of positive pressure in addition to normal saline reduces the incidence rate of partial occlusions. The type of treatment, blood sample collection, and treatment schedule are important determinants of partial occlusions. Nurses play a key role in maintaining a functioning port using positive pressure during the flushing techniques. Certain risk factors must be monitored to prevent partial occlusions, and certain patients are more likely to present with port-related problems.

Effects of Shock-Breakout Pressure on Ejection of Micron-Scale Material from Shocked Tin Surfaces

NASA Astrophysics Data System (ADS)

Zellner, Michael; Hammerberg, James; Hixson, Robert; Morley, Kevin; Obst, Andrew; Olson, Russell; Payton, Jeremy; Rigg, Paulo; Buttler, William; Grover, Michael; Iverson, Adam; Macrum, Gregory; Stevens, Gerald; Turley, William; Veeser, Lynn; Routley, Nathan

2007-06-01

Los Alamos National Lab (LANL) is actively engaged in the development of a model to predict the formation of micron-scale fragments ejected (ejecta) from shocked metal surfaces. The LANL ejecta model considers that the amount of ejecta is mainly related to the material's phase on shock release at the free-surface. This effort investigates the relation between ejecta production and shock-breakout pressure for Sn shocked with high explosives to pressures near the solid-on-release/partial-liquid-on-release phase transition region. We found that the amount of ejecta produced for shock-breakout pressures that resulted in partial-liquid-on-release increased significantly compared to that which resulted in solid-on-release. Additionally, we found that the amount of ejecta remained relatively constant within the partial-liquid-on-release, regardless of shock-breakout pressure.

Pressure Effects on the Ejection of Material from Shocked Tin Surfaces

NASA Astrophysics Data System (ADS)

Zellner, M. B.; Grover, M.; Hammerberg, J. E.; Hixson, R. S.; Iverson, A. J.; Macrum, G. S.; Morley, K. B.; Obst, A. W.; Olson, R. T.; Payton, J. R.; Rigg, P. A.; Routley, N.; Stevens, G. D.; Turley, W. D.; Veeser, L.; Buttler, W. T.

2007-12-01

Los Alamos National Lab (LANL) is actively engaged in the development of a model to predict the formation of micron-scale fragments ejected (ejecta) from shocked metals that have surface defects. The LANL ejecta model considers that the amount of ejecta is mainly related to the material's phase on shock release at the free-surface. This effort investigates the relation between ejecta production and shock-breakout pressure for Sn shocked with high explosives to pressures near the solid-on-release/partial-liquid-on-release phase transition region. We found that the amount of ejecta produced for shock-breakout pressures that resulted in partial-liquid-on-release increased significantly compared to that which resulted in solid-on-release. Additionally, we found that the amount of ejecta remained relatively constant within the partial-liquid-on-release, regardless of shock-breakout pressure.

Fuel cell serves as oxygen level detector

NASA Technical Reports Server (NTRS)

1965-01-01

Monitoring the oxygen level in the air is accomplished by a fuel cell detector whose voltage output is proportional to the partial pressure of oxygen in the sampled gas. The relationship between output voltage and partial pressure of oxygen can be calibrated.

Method of enhancing selective isotope desorption from metals

DOEpatents

Knize, Randall J.; Cecchi, Joseph L.

1984-01-01

A method of enhancing the thermal desorption of a first isotope of a diatomic gas from a metal comprises the steps of (a) establishing a partial pressure of a second isotope of the diatomic gas in vicinity of the metal; heating the metal to a temperature such that the first isotope is desorbed from the metal; and reducing the partial pressure of the desorbed first isotope while maintaining the partial pressure of the second isotope substantially constant. The method is especially useful for enhancing the desorption of tritium from the Zr-Al getter in a plasma confinement device.

Study on the intrinsic defects in ZnO by combing first-principle and thermodynamic calculations

NASA Astrophysics Data System (ADS)

Ma, Changmin; Liu, Tingyu; Chang, Qiuxiang

2015-11-01

In this paper, the intrinsic point defects in ZnO crystal have been studied by the approach that integrates first-principles, thermodynamic calculations and the contributions of vibrational entropy. With temperature increasing and oxygen partial pressure decreasing, the formation energies of oxygen vacancy (VO), zinc interstitial (Zni) and zinc anti-site (ZnO) are decreasing, while it increases for zinc vacancy (VZn), oxygen interstitial (Oi) and oxygen anti-site (OZn). They are more sensitive to temperature than oxygen partial pressure. There are two interesting phenomena. First, VO or VZn have the lowest formation energies for whole Fermi level at special environment condition (such as at T = 300K, about PO2 = 10-10atm or T = 1500K, about PO2 = 104atm) and intrinsic p-type doping of ZnO is possible by VZn at these special conditions. Second, VO as donors have lowest formation energy for all Fermi level at high temperature and low oxygen partial pressure (T = 1500K, PO2 = 10-10atm). According to our analysis, the VO could produce n-type doping in ZnO at these special conditions and change p-type ZnO to n-type ZnO at condition from low temperature and high oxygen partial pressure to high temperature and low oxygen partial pressure.

Development and evaluation of gas-pressurized elastic sleeves for extravehicular activity.

PubMed

Tanaka, Kunihiko; Tohnan, Momoka; Abe, Chikara; Iwata, Chihiro; Yamagata, Kenji; Tanaka, Masao; Tanaka, Nobuyuki; Morita, Hironobu

2010-07-01

In space, mobility of the current extravehicular activity space suit is limited due to the pressure differential between the inside and outside of the suit. We have previously demonstrated that an elastic glove increased mobility when compared with a non-elastic glove such as that found in the current suit. Extending this work, we hypothesized that an elastic sleeve would also have more mobility compared to a non-elastic sleeve, but a partially elastic sleeve, consisting of elastic joints sewn to non-elastic parts in low mobility areas, might generate similar mobility to a wholly elastic sleeve. The right arms of 10 volunteers were studied with wholly elastic, partially elastic, and non-elastic sleeves in a chamber pressure of -220 mmHg. Range of motion (ROM) of the wrist and electromyography (EMG) of the flexor carpi radialis muscle and the biceps brachii muscle during wrist and elbow flexion were measured. ROM of the wrist was similar among all the sleeves. However, EMG amplitudes during wrist flexion with both elastic sleeves were significantly smaller than that with the non-elastic sleeve. EMG amplitudes during 90 degrees of elbow flexion were also significantly smaller in both elastic sleeves. However, no significant difference in EMG amplitudes was observed between the two elastic sleeves (0.53 +/- 0.06, 0.56 +/- 0.07, 1.14 +/- 0.10 V for wholly elastic, partially elastic, and non-elastic sleeves, respectively). The mobility of elastic sleeves is better than that of a non-elastic sleeve. Elasticity over the joints is important; however the elasticity of the other parts does not appear to affect mobility.

The last stage of Earth's formation: Increasing the pressure

NASA Astrophysics Data System (ADS)

Lock, S. J.; Stewart, S. T.; Mukhopadhyay, S.

2017-12-01

A range of high-energy, high-angular momentum (AM) giant impacts have been proposed as a potential trigger for lunar origin. High-energy, high-AM collisions create a previously unrecognized planetary object, called a synestia. Terrestrial synestias exceed the corotation limit for a rocky planet, forming an extended structure with a corotating inner region and disk-like outer region. We demonstrate that the internal pressures of Earth-like planets do not increase monotonically during the giant impact stage, but can vary substantially in response to changes in rotation and thermal state. The internal pressures in an impact-generated synestia are much lower than in condensed, slowly rotating planets of the same mass. For example, the core-mantle boundary (CMB) pressure can be as low as 60 GPa for a synestia with Earth mass and composition, compared to 136 GPa in the present-day Earth. The lower pressures are due to the low density and rapid rotation of the post-impact structure. After a high-AM Moon-forming impact, the internal pressures in the interior of the synestia would have increased to present-day Earth values in two stages: first by vapor condensation and second by removal of AM from the Earth during the tidal evolution of the Moon. The pressure evolution of the Earth has several implications. Metal-silicate equilibration after the impact would have occurred at much lower pressures than has previously been assumed. The observed moderately siderophile element abundances in the mantle may be consistent with equilibration at the bottom of a deep, lower-pressure magma ocean. In addition, the pressure at the CMB during cooling is coincident with, or lower than, the proposed intersection of liquid adiabats with the mantle liquidus. The mantle would hence freeze from the bottom up and there would be no basal magma ocean. The subsequent pressure increase and tidal heating due to the Moon's orbital evolution likely induces melting in the lowermost mantle. Increasing pressure in the upper mantle also leads to exothermic and endothermic phase changes potentially producing partial melts in the mid-mantle. High-pressure partial melts could produce precursor material for the seismically and chemically anomalous regions that are observed in the lower mantle today.

One man electrochemical air revitalization system

NASA Technical Reports Server (NTRS)

Huddleston, J. C.; Aylward, J. R.

1975-01-01

An integrated water vapor electrolysis (WVE) hydrogen depolarized CO2 concentrator (HDC) system sized for one man support over a wide range of inlet air conditions was designed, fabricated, and tested. Data obtained during 110 days of testing verified that this system can provide the necessary oxygen, CO2 removal, and partial humidity control to support one man (without exceeding a cabin partial pressure of 3.0 mmHg for CO2 and while maintaining a 20% oxygen level), when operated at a WVE current of 50 amperes and an HDC current of 18 amperes. An evaluation to determine the physical properties of tetramethylammonium bicarbonate (TMAC) and hydroxide was made. This provides the necessary electrolyte information for designing an HDC cell using TMAC.

Magnetism of Amorphous and Nano-Crystallized Dc-Sputter-Deposited MgO Thin Films

PubMed Central

Mahadeva, Sreekanth K.; Fan, Jincheng; Biswas, Anis; Sreelatha, K.S.; Belova, Lyubov; Rao, K.V.

2013-01-01

We report a systematic study of room-temperature ferromagnetism (RTFM) in pristine MgO thin films in their amorphous and nano-crystalline states. The as deposited dc-sputtered films of pristine MgO on Si substrates using a metallic Mg target in an O2 containing working gas atmosphere of (N2 + O2) are found to be X-ray amorphous. All these films obtained with oxygen partial pressure (PO2) ~10% to 80% while maintaining the same total pressure of the working gas are found to be ferromagnetic at room temperature. The room temperature saturation magnetization (MS) value of 2.68 emu/cm3 obtained for the MgO film deposited in PO2 of 10% increases to 9.62 emu/cm3 for film deposited at PO2 of 40%. However, the MS values decrease steadily for further increase of oxygen partial pressure during deposition. On thermal annealing at temperatures in the range 600 to 800 °C, the films become nanocrystalline and as the crystallite size grows with longer annealing times and higher temperature, MS decreases. Our study clearly points out that it is possible to tailor the magnetic properties of thin films of MgO. The room temperature ferromagnetism in MgO films is attributed to the presence of Mg cation vacancies. PMID:28348346

Multi-Fidelity Simulation of a Turbofan Engine With Results Zoomed Into Mini-Maps for a Zero-D Cycle Simulation

NASA Technical Reports Server (NTRS)

Turner, Mark G.; Reed, John A.; Ryder, Robert; Veres, Joseph P.

2004-01-01

A Zero-D cycle simulation of the GE90-94B high bypass turbofan engine has been achieved utilizing mini-maps generated from a high-fidelity simulation. The simulation utilizes the Numerical Propulsion System Simulation (NPSS) thermodynamic cycle modeling system coupled to a high-fidelity full-engine model represented by a set of coupled 3D computational fluid dynamic (CFD) component models. Boundary conditions from the balanced, steady state cycle model are used to define component boundary conditions in the full-engine model. Operating characteristics of the 3D component models are integrated into the cycle model via partial performance maps generated from the CFD flow solutions using one-dimensional mean line turbomachinery programs. This paper highlights the generation of the high-pressure compressor, booster, and fan partial performance maps, as well as turbine maps for the high pressure and low pressure turbine. These are actually "mini-maps" in the sense that they are developed only for a narrow operating range of the component. Results are compared between actual cycle data at a take-off condition and the comparable condition utilizing these mini-maps. The mini-maps are also presented with comparison to actual component data where possible.

In situ measurement of tritium permeation through stainless steel

NASA Astrophysics Data System (ADS)

Luscher, Walter G.; Senor, David J.; Clayton, Kevin K.; Longhurst, Glen R.

2013-06-01

The TMIST-2 irradiation experiment was conducted in the Advanced Test Reactor at Idaho National Laboratory to evaluate tritium permeation through Type 316 stainless steel (316 SS). The interior of a 316 SS seamless tube specimen was exposed to a 4He carrier gas mixed with a specified quantity of tritium (T2) to yield partial pressures of 0.1, 5, and 50 Pa at 292 °C and 330 °C. In situ tritium permeation measurements were made by passing a He-Ne sweep gas over the outer surface of the specimen to carry the permeated tritium to a bubbler column for liquid scintillation counting. Results from in situ permeation measurements were compared with predictions based on an ex-reactor permeation correlation in the literature. In situ permeation data were also used to derive an in-reactor permeation correlation as a function of temperature and pressure over the ranges considered in this study. In addition, the triton recoil contribution to tritium permeation, which results from the transmutation of 3He to T, was also evaluated by introducing a 4He carrier gas mixed with 3He at a partial pressure of 1013 Pa at 330 °C. Less than 3% of the tritium resulting from 3He transmutation contributed to tritium permeation.

Reactor cell assembly for use in spectroscopy and microscopy applications

DOEpatents

Grindstaff, Quirinus; Stowe, Ashley Clinton; Smyrl, Norm; Powell, Louis; McLane, Sam

2015-08-04

The present disclosure provides a reactor cell assembly that utilizes a novel design and that is wholly or partially manufactured from Aluminum, such that reactions involving Hydrogen, for example, including solid-gas reactions and thermal decomposition reactions, are not affected by any degree of Hydrogen outgassing. This reactor cell assembly can be utilized in a wide range of optical and laser spectroscopy applications, as well as optical microscopy applications, including high-temperature and high-pressure applications. The result is that the elucidation of the role of Hydrogen in the reactions studied can be achieved. Various window assemblies can be utilized, such that high temperatures and high pressures can be accommodated and the signals obtained can be optimized.

Theory of low transitions in CO discharge lasers

NASA Technical Reports Server (NTRS)

Sidney, B. D.; Mcinuille, R. M.; Smith, N. S.; Hassan, H. A.

1976-01-01

A self consistent theoretical model which couples the electron and heavy particle finite rate kinetics with the optical and fluid dynamic processes has been employed to identify the various parameters and explain the mechanism responsible for producing low lying transitions in slow flowing CO lasers. It is found that lasing on low lying transitions can be achieved at low temperatures for low pressures (or low flow rates) together with high partial pressures of the He and N2. The role of N2 has been identified as an additive responsible for reducing the electron temperature to a range where the transfer of electrical power to the lower vibrational modes of CO is optimum.

Sea-level haemoglobin concentration is associated with greater exercise capacity in Tibetan males at 4200 m.

PubMed

Wagner, P D; Simonson, T S; Wei, G; Wagner, H E; Wuren, T; Qin, G; Yan, M; Ge, R L

2015-11-01

What is the topic of this review? Recent developments link relatively lower hemoglobin concentration in Tibetans at high altitude to exercise capacity and components of oxygen transport. What advances does it highlight? Haemoglobin concentration (ranging from 15.2 to 22.9 g dl(-1) ) in Tibetan males was negatively associated with peak oxygen (O2 ) uptake per kilogram, cardiac output and muscle O2 diffusion conductance. Most variance in the peak O2 uptake per kilogram of Tibetan males was attributed to cardiac output, muscle diffusional conductance and arterial partial pressure of CO2 . The mechanisms underlying these differences in oxygen transport in Tibetans require additional analyses. Despite residence at >4000 m above sea level, many Tibetan highlanders, unlike Andean counterparts and lowlanders at altitude, exhibit haemoglobin concentration ([Hb]) within the typical sea-level range. Genetic adaptations in Tibetans are associated with this relatively low [Hb], yet the functional relevance of the lower [Hb] remains unknown. To address this, we examined each major step of the oxygen transport cascade [ventilation (VE), cardiac output (QT) and diffusional conductance in lung (DL) and muscle (DM)] in Tibetan males at maximal exercise on a cycle ergometer. Ranging from 15.2 to 22.9 g dl(-1) , [Hb] was negatively associated with peak O2 uptake per kilogram (r = -0.45, P < 0.05) and both cardiac output (QT/kg: r = -0.54, P < 0.02) and muscle O2 diffusion conductance (DM/kg: r = -0.44, P < 0.05) but not ventilation, arterial partial pressure of O2 or pulmonary diffusing capacity. Most variance in peak O2 uptake per kilogram was attributed to QT, DM and arterial partial pressure of CO2 (r(2)  = 0.90). In summary, lack of polycythaemia in Tibetans is associated with increased exercise capacity, which is explained by elevated cardiac, muscle and, to a small extent, ventilatory responses rather than pulmonary gas exchange. Whether lower [Hb] is the cause or result of these changes in O2 transport or is causally unrelated will require additional study. © 2015 The Authors. Experimental Physiology © 2015 The Physiological Society.

Reversible effects of oxygen partial pressure on genes associated with placental angiogenesis and differentiation in primary-term cytotrophoblast cell culture.

PubMed

Debiève, F; Depoix, C; Gruson, D; Hubinont, C

2013-09-01

Timely regulated changes in oxygen partial pressure are important for placental formation. Disturbances could be responsible for pregnancy-related diseases like preeclampsia and intrauterine growth restriction. We aimed to (i) determine the effect of oxygen partial pressure on cytotrophoblast differentiation; (ii) measure mRNA expression and protein secretion from genes associated with placental angiogenesis; and (iii) determine the reversibility of these effects at different oxygen partial pressures. Term cytotrophoblasts were incubated at 21% and 2.5% O2 for 96 hr, or were switched between the two oxygen concentrations after 48 hr. Real-time PCR and enzyme-linked immunosorbent assays (ELISAs) were used to evaluate cell fusion and differentiation, measuring transcript levels for those genes involved in cell fusion and placental angiogenesis, including VEGF, PlGF, VEGFR1, sVEGFR1, sENG, INHA, and GCM1. Cytotrophoblasts underwent fusion and differentiation in 2.5% O2 . PlGF expression was inhibited while sVEGFR1 expression increased. VEGF and sENG mRNA expressions increased in 2.5% compared to 21% O2 , but no protein was detected in the cell supernatants. Finally, GCM1 mRNA expression increased during trophoblast differentiation at 21% O2 , but was inhibited at 2.5% O2 . These mRNA expression effects were reversed by returning the cells to 21% O2 . Thus, low-oxygen partial pressure does not inhibit term-cytotrophoblast cell fusion and differentiation in vitro. Lowering the oxygen partial pressure from 21% to 2.5% caused normal-term trophoblasts to reversibly modify their expression of genes associated with placental angiogenesis. This suggests that modifications observed in pregnancy diseases such as preeclampsia or growth retardation are probably due to an extrinsic effect on trophoblasts. Copyright © 2013 Wiley Periodicals, Inc.

Measurement of alveolar oxygen partial pressure in the rat lung using Carr-Purcell-Meiboom-Gill spin-spin relaxation times of hyperpolarized 3He and 129Xe at 74 mT.

PubMed

Kraayvanger, Ryan J; Bidinosti, Christopher P; Dominguez-Viqueira, William; Parra-Robles, Juan; Fox, Matthew; Lam, Wilfred W; Santyr, Giles E

2010-11-01

Regional measurement of alveolar oxygen partial pressure can be obtained from the relaxation rates of hyperpolarized noble gases, (3) He and (129) Xe, in the lungs. Recently, it has been demonstrated that measurements of alveolar oxygen partial pressure can be obtained using the spin-spin relaxation rate (R(2) ) of (3) He at low magnetic field strengths (<0.1 T) in vivo. R(2) measurements can be achieved efficiently using the Carr-Purcell-Meiboom-Gill pulse sequence. In this work, alveolar oxygen partial pressure measurements based on Carr-Purcell-Meiboom-Gill R(2) values of hyperpolarized (3) He and (129) Xe in vitro and in vivo in the rat lung at low magnetic field strength (74 mT) are presented. In vitro spin-spin relaxivity constants for (3) He and (129) Xe were determined to be (5.2 ± 0.6) × 10(-6) Pa(-1) sec(-1) and (7.3 ± 0.4) × 10(-6) Pa(-1) s(-1) compared with spin-lattice relaxivity constants of (4.0 ± 0.4) × 10(-6) Pa(-1) s(-1) and (4.3 ± 1.3) × 10(-6) Pa(-1) s(-1), respectively. In vivo experimental measurements of alveolar oxygen partial pressure using (3) He in whole rat lung show good agreement (r(2) = 0.973) with predictions based on lung volumes and ventilation parameters. For (129) Xe, multicomponent relaxation was observed with one component exhibiting an increase in R(2) with decreasing alveolar oxygen partial pressure. Copyright © 2010 Wiley-Liss, Inc.

A novel method of measuring the concentration of anaesthetic vapours using a dew-point hygrometer.

PubMed

Wilkes, A R; Mapleson, W W; Mecklenburgh, J S

1994-02-01

The Antoine equation relates the saturated vapour pressure of a volatile substance, such as an anaesthetic agent, to the temperature. The measurement of the 'dew-point' of a dry gas mixture containing a volatile anaesthetic agent by a dew-point hygrometer permits the determination of the partial pressure of the anaesthetic agent. The accuracy of this technique is limited only by the accuracy of the Antoine coefficients and of the temperature measurement. Comparing measurements by the dew-point method with measurements by refractometry showed systematic discrepancies up to 0.2% and random discrepancies with SDS up to 0.07% concentration in the 1% to 5% range for three volatile anaesthetics. The systematic discrepancies may be due to errors in available data for the vapour pressures and/or the refractive indices of the anaesthetics.

The effect of compression on individual pressure vessel nickel/hydrogen components

NASA Technical Reports Server (NTRS)

Manzo, Michelle A.; Perez-Davis, Marla E.

1988-01-01

Compression tests were performed on representative Individual Pressure Vessel (IPV) Nickel/Hydrogen cell components in an effort to better understand the effects of force on component compression and the interactions of components under compression. It appears that the separator is the most easily compressed of all of the stack components. It will typically partially compress before any of the other components begin to compress. The compression characteristics of the cell components in assembly differed considerably from what would be predicted based on individual compression characteristics. Component interactions played a significant role in the stack response to compression. The results of the compression tests were factored into the design and selection of Belleville washers added to the cell stack to accommodate nickel electrode expansion while keeping the pressure on the stack within a reasonable range of the original preset.

The effects of endothelin-1 on the cardiorespiratory physiology of the freshwater trout (Oncorhynchus mykiss) and the marine dogfish (Squalus acanthias).

PubMed

Perry, S F; Montpetit, C J; McKendry, J; Desforges, P R; Gilmour, K M; Wood, C M; Olson, K R

2001-11-01

The aim of the present study was to evaluate the effects of endothelin-l-elicited cardiovascular events on respiratory gas transfer in the freshwater rainbow trout (Oncorhynchus mykiss) and the marine dogfish (Squalus acanthias). In both species, endothelin-1 (666 pmol kg(-1)) caused a rapid (within 4 min) reduction (ca. 30-50 mmHg) in arterial blood partial pressure of O2. The effects of endothelin-1 on arterial blood partial pressure of CO2 were not synchronised with the changes in O2 partial pressure and the responses were markedly different in trout and dogfish. In trout, arterial CO2 partial pressure was increased transiently by approximately 1.0 mmHg but the onset of the response was delayed and occurred 12 min after endothelin-1 injection. In contrast, CO2 partial pressure remained more-or-less constant in dogfish after injection of endothelin-1 and was increased only slightly (approximately 0.1 mmHg) after 60 min. Pre-treatment of trout with bovine carbonic anhydrase (5 mg ml(-1)) eliminated the increase in CO2 partial pressure that was normally observed after endothelin-1 injection. In both species, endothelin-1 injection caused a decrease in arterial blood pH that mirrored the changes in CO2 partial pressure. Endothelin-1 injection was associated with transient (trout) or persistent (dogfish) hyperventilation as indicated by pronounced increases in breathing frequency and amplitude. In trout, arterial blood pressure remained constant or was decreased slightly and was accompanied by a transient increase in systemic resistance, and a temporary reduction in cardiac output. The decrease in cardiac output was caused solely by a reduction in cardiac frequency; cardiac stroke volume was unaffected. In dogfish, arterial blood pressure was lowered by approximately 10 mmHg at 6-10 min after endothelin-1 injection but then was rapidly restored to pre-injection levels. The decrease in arterial blood pressure reflected an increase in branchial vascular resistance (as determined using in situ perfused gill preparations) that was accompanied by simultaneous decreases in systemic resistance and cardiac output. Cardiac frequency and stroke volume were reduced by endothelin-1 injection and thus both variables contributed to the changes in cardiac output. We conclude that the net consequences of endothelin-1 on arterial blood gases result from the opposing effects of reduced gill functional surface area (caused by vasoconstriction) and an increase in blood residence time within the gill (caused by decreased cardiac output.

Feasibility of measuring dissolved carbon dioxide based on head space partial pressures

USGS Publications Warehouse

Watten, B.J.; Boyd, C.E.; Schwartz, M.F.; Summerfelt, S.T.; Brazil, B.L.

2004-01-01

We describe an instrument prototype that measures dissolved carbon dioxide (DC) without need for standard wetted probe membranes or titration. DC is calculated using Henry's Law, water temperature, and the steady-state partial pressure of carbon dioxide that develops within the instrument's vertical gas-liquid contacting chamber. Gas-phase partial pressures were determined with either an infrared detector (ID) or by measuring voltage developed by a pH electrode immersed in an isolated sodium carbonate solution (SC) sparged with recirculated head space gas. Calculated DC concentrations were compared with those obtained by titration over a range of DC (2, 4, 8, 12, 16, 20, 24, and 28mg/l), total alkalinity (35, 120, and 250mg/l as CaCO3), total dissolved gas pressure (-178 to 120 mmHg), and dissolved oxygen concentrations (7, 14, and 18 mg/l). Statistically significant (P < 0.001) correlations were established between head space (ID) and titrimetrically determined DC concentrations (R2 = 0.987-0.999, N = 96). Millivolt and titrimetric values from the SC solution tests were also correlated (P < 0.001, R 2 = 0.997, N = 16). The absolute and relative error associated with the use of the ID and SC solution averaged 0.9mg/l DC and 7.0% and 0.6 mg/l DC and 9.6%, respectively. The precision of DC estimates established in a second test series was good; coefficients of variation (100(SD/mean)) for the head space (ID) and titration analyses were 0.99% and 1.7%. Precision of the SC solution method was 1.3%. In a third test series, a single ID was coupled with four replicate head space units so as to permit sequential monitoring (15 min intervals) of a common water source. Here, appropriate gas samples were secured using a series of solenoid valves (1.6 mm bore) activated by a time-based controller. This system configuration reduced the capital cost per sample site from US$ 2695 to 876. Absolute error averaged 2.9, 3.1, 3.7, and 2.7 mg/ l for replicates 1-4 (N = 36) during a 21-day test period (DC range, 36-40 mg/l). The ID meter was then modified so as to provide for DO as well as DC measurements across components of an intensive fish production system. ?? 2003 Elsevier B.V. All rights reserved.

Desulphurization of coal using borax

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yaman, S.; Kuecuekbayrak, S.

1996-12-31

In this study, a high sulphur Turkish lignite was mixed with various amounts of solid borax [Na{sub 2}B{sub 4}O{sub 7}10H{sub 2}O] and then these mixtures were subjected to various oxydesulphurization processes. Effects of amount of borax, temperature and partial pressure of oxygen on sulphur removal and coal recovery were investigated in the ranges of 0.625--15.000 g for 5 g lignite, 423--498 K, 0.0--1.5 MPa, respectively.

Krikalev at work in Node 1

NASA Image and Video Library

2001-02-07

STS098-346-0032 (7-20 February 2001) --- Cosmonaut Sergei K. Krikalev, Expedition One flight engineer representing the Russian Aviation and Space Agency, carries the Vozdukh in the Unity node. Vozdukh is designed to maintain the partial pressure of carbon dioxide in the cabin air within the medically permissible range for long-duration exposure. It provides the primary means of removing CO2 from the outpost's atmosphere, and its operation is based on the use of regenerated adsorbers of CO2.

Airway exchange of highly soluble gases.

PubMed

Hlastala, Michael P; Powell, Frank L; Anderson, Joseph C

2013-03-01

Highly blood soluble gases exchange with the bronchial circulation in the airways. On inhalation, air absorbs highly soluble gases from the airway mucosa and equilibrates with the blood before reaching the alveoli. Highly soluble gas partial pressure is identical throughout all alveoli. At the end of exhalation the partial pressure of a highly soluble gas decreases from the alveolar level in the terminal bronchioles to the end-exhaled partial pressure at the mouth. A mathematical model simulated the airway exchange of four gases (methyl isobutyl ketone, acetone, ethanol, and propylene glycol monomethyl ether) that have high water and blood solubility. The impact of solubility on the relative distribution of airway exchange was studied. We conclude that an increase in water solubility shifts the distribution of gas exchange toward the mouth. Of the four gases studied, ethanol had the greatest decrease in partial pressure from the alveolus to the mouth at end exhalation. Single exhalation breath tests are inappropriate for estimating alveolar levels of highly soluble gases, particularly for ethanol.

Airway exchange of highly soluble gases

PubMed Central

Powell, Frank L.; Anderson, Joseph C.

2013-01-01

Highly blood soluble gases exchange with the bronchial circulation in the airways. On inhalation, air absorbs highly soluble gases from the airway mucosa and equilibrates with the blood before reaching the alveoli. Highly soluble gas partial pressure is identical throughout all alveoli. At the end of exhalation the partial pressure of a highly soluble gas decreases from the alveolar level in the terminal bronchioles to the end-exhaled partial pressure at the mouth. A mathematical model simulated the airway exchange of four gases (methyl isobutyl ketone, acetone, ethanol, and propylene glycol monomethyl ether) that have high water and blood solubility. The impact of solubility on the relative distribution of airway exchange was studied. We conclude that an increase in water solubility shifts the distribution of gas exchange toward the mouth. Of the four gases studied, ethanol had the greatest decrease in partial pressure from the alveolus to the mouth at end exhalation. Single exhalation breath tests are inappropriate for estimating alveolar levels of highly soluble gases, particularly for ethanol. PMID:23305981

Oxidation Behavior of Carbon Fiber-Reinforced Composites

NASA Technical Reports Server (NTRS)

Sullivan, Roy M.

2008-01-01

OXIMAP is a numerical (FEA-based) solution tool capable of calculating the carbon fiber and fiber coating oxidation patterns within any arbitrarily shaped carbon silicon carbide composite structure as a function of time, temperature, and the environmental oxygen partial pressure. The mathematical formulation is derived from the mechanics of the flow of ideal gases through a chemically reacting, porous solid. The result of the formulation is a set of two coupled, non-linear differential equations written in terms of the oxidant and oxide partial pressures. The differential equations are solved simultaneously to obtain the partial vapor pressures of the oxidant and oxides as a function of the spatial location and time. The local rate of carbon oxidation is determined at each time step using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The non-linear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual finite element method, allowing for the solution of the differential equations numerically.

Effects of various oxygen partial pressures on Ti-doped ZnO thin film transistors fabricated on flexible plastic substrate

NASA Astrophysics Data System (ADS)

Cui, Guodong; Han, Dedong; Yu, Wen; Shi, Pan; Zhang, Yi; Huang, Lingling; Cong, Yingying; Zhou, Xiaoliang; Zhang, Xiaomi; Zhang, Shengdong; Zhang, Xing; Wang, Yi

2016-04-01

By applying a novel active layer of titanium zinc oxide (TiZO), we have successfully fabricated fully transparent thin-film transistors (TFTs) with a bottom gate structure fabricated on a flexible plastic substrate at low temperatures. The effects of various oxygen partial pressures during channel deposition were studied to improve the device performance. We found that the oxygen partial pressure during channel deposition has a significant impact on the performance of TiZO TFTs, and that the TFT developed under 10% oxygen partial pressure exhibits superior performance with a low threshold voltage (V th) of 2.37 V, a high saturation mobility (μsat) of 125.4 cm2 V-1 s-1, a steep subthreshold swing (SS) of 195 mV/decade and a high I on/I off ratio of 3.05 × 108. These results suggest that TiZO thin films are promising for high-performance fully transparent flexible TFTs and displays.

[Correlation between the inspired fraction of oxygen, maternal partial oxygen pressure, and fetal partial oxygen pressure during cesarean section of normal pregnancies].

PubMed

Castro, Carlos Henrique Viana de; Cruvinel, Marcos Guilherme Cunha; Carneiro, Fabiano Soares; Silva, Yerkes Pereira; Cabral, Antônio Carlos Vieira; Bessa, Roberto Cardoso

2009-01-01

Despite changes in pulmonary function, maternal oxygenation is maintained during obstetric regional blocks. But in those situations, the administration of supplementary oxygen to parturients is a common practice. Good fetal oxygenation is the main justification; however, this has not been proven. The objective of this randomized, prospective study was to test the hypothesis of whether maternal hyperoxia is correlated with an increase in fetal gasometric parameters in elective cesarean sections. Arterial blood gases of 20 parturients undergoing spinal block with different inspired fractions of oxygen were evaluated and correlated with fetal arterial blood gases. An increase in maternal inspired fraction of oxygen did not show any correlation with an increase of fetal partial oxygen pressure. Induction of maternal hyperoxia by the administration of supplementary oxygen did not increase fetal partial oxygen pressure. Fetal gasometric parameters did not change even when maternal parameters changed, induced by hyperoxia, during cesarean section under spinal block.

Respiratory gas exchange of high altitude adapted chick embryos

NASA Technical Reports Server (NTRS)

Wangensteen, O. D.; Rahn, H.; Burton, R. R.; Smith, A. H.

1974-01-01

Study of gas exchange by embryos from chickens acclimatized to an altitude of 3800 m. The oxygen partial pressure and carbon dioxide partial pressure differences across the egg shell were measured and found to be less than the values previously reported for sea-level eggs by about a factor of two. Further measurements of embryonic oxygen consumption and shell conductivity to oxygen indicated that, compared to eggs at sea level, oxygen consumption was reduced by a factor of 0.58 while conductivity to oxygen was increased only by a factor of 1.07 in the high-altitude eggs. These independent measurements predict the change in oxygen partial pressure across the egg shell of the high-altitude eggs to be only 0.54 times that of sea-level eggs; the directly measured factor was 0.53. The authors conclude that at high altitude, a major adaptation of the chick embryo is a reduced metabolism which decreases the change in oxygen partial pressure across the egg shell since its gas conductivity remains essentially unchanged.

Biomass hydrolysis inhibition at high hydrogen partial pressure in solid-state anaerobic digestion.

PubMed

Cazier, E A; Trably, E; Steyer, J P; Escudie, R

2015-08-01

In solid-state anaerobic digestion, so-called ss-AD, biogas production is inhibited at high total solids contents. Such inhibition is likely caused by a slow diffusion of dissolved reaction intermediates that locally accumulate. In this study, we investigated the effect of H2 and CO2 partial pressure on ss-AD. Partial pressure of H2 and/or CO2 was artificially fixed, from 0 to 1 557mbars for H2 and from 0 to 427mbars for CO2. High partial pressure of H2 showed a significant effect on methanogenesis, while CO2 had no impact. At high [Formula: see text] , the overall substrate degradation decreased with no accumulation of metabolites from acidogenic bacteria, indicating that the hydrolytic activity was specifically impacted. Interestingly, such inhibition did not occur when CO2 was added with H2. This result suggests that CO2 gas transfer is probably a key factor in ss-AD from biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

Quantitation of dissolved gas content in emulsions and in blood using mass spectrometric detection

PubMed Central

Grimley, Everett; Turner, Nicole; Newell, Clayton; Simpkins, Cuthbert; Rodriguez, Juan

2011-01-01

Quantitation of dissolved gases in blood or in other biological media is essential for understanding the dynamics of metabolic processes. Current detection techniques, while enabling rapid and convenient assessment of dissolved gases, provide only direct information on the partial pressure of gases dissolved in the aqueous fraction of the fluid. The more relevant quantity known as gas content, which refers to the total amount of the gas in all fractions of the sample, can be inferred from those partial pressures, but only indirectly through mathematical modeling. Here we describe a simple mass spectrometric technique for rapid and direct quantitation of gas content for a wide range of gases. The technique is based on a mass spectrometer detector that continuously monitors gases that are rapidly extracted from samples injected into a purge vessel. The accuracy and sample processing speed of the system is demonstrated with experiments that reproduce within minutes literature values for the solubility of various gases in water. The capability of the technique is further demonstrated through accurate determination of O2 content in a lipid emulsion and in whole blood, using as little as 20 μL of sample. The approach to gas content quantitation described here should greatly expand the range of animals and conditions that may be used in studies of metabolic gas exchange, and facilitate the development of artificial oxygen carriers and resuscitation fluids. PMID:21497566

Infragravity waves on fringing reefs in the tropical Pacific: Dynamic setup

NASA Astrophysics Data System (ADS)

Becker, J. M.; Merrifield, M. A.; Yoon, H.

2016-05-01

Cross-shore pressure and current observations from four fringing reefs of lengths ranging from 135 to 420 m reveal energetic low-frequency (˜0.001-0.05 Hz) motions. The spatial structure and temporal amplitudes of an empirical orthogonal function analysis of the pressure measurements suggest the dominant low-frequency variability is modal. Incoming and outgoing linear flux estimates also support partially standing modes on the reef flat during energetic events. A cross-covariance analysis suggests that breakpoint forcing excites these partially standing modes, similar to previous findings at other steep reefs. The dynamics of Symonds et al. (1982) with damping are applied to a step reef, with forcing obtained by extending a point break model of Vetter et al. (2010) for breaking wave setup to the low-frequency band using the shoaled envelope of the incident free surface elevation. A one parameter, linear analytical model for the reef flat free surface elevation is presented, which describes between 75% and 97% of the variance of the observed low-frequency shoreline significant wave height for all reefs considered over a range of conditions. The linear model contains a single dimensionless parameter that is the ratio of the inertial to dissipative time scales, and the observations from this study exhibit more low-frequency variability when the dissipative time scale is greater than the inertial time scale for the steep reefs considered.

Influence of oxygen partial pressure on surface tension and its temperature coefficient of molten iron

NASA Astrophysics Data System (ADS)

Ozawa, S.; Suzuki, S.; Hibiya, T.; Fukuyama, H.

2011-01-01

Influences of oxygen partial pressure, PO2, of ambient atmosphere and temperature on surface tension and its temperature coefficient for molten iron were experimentally investigated by an oscillating droplet method using an electromagnetic levitation furnace. We successfully measured the surface tension of molten iron over a very wide temperature range of 780 K including undercooling condition in a well controlled PO2 atmosphere. When PO2 is fixed at 10-2 Pa at the inlet of the chamber, a "boomerang shape" temperature dependence of surface tension was experimentally observed; surface tension increased and then decreased with increasing temperature. The pure surface tension of molten iron was deduced from the negative temperature coefficient in the boomerang shape temperature dependence. When the surface tension was measured under the H2-containing gas atmosphere, surface tension did not show a linear relationship against temperature. The temperature dependence of the surface tension shows anomalous kink at around 1850 K due to competition between the temperature dependence of PO2 and that of the equilibrium constant of oxygen adsorption.

[Relation between ultrasound-measured diaphragm movement and partial pressure of carbon dioxide in blood from patients with acute hypercapnic respiratory failure after the start of noninvasive ventilation in an emergency department].

PubMed

Sánchez-Nicolás, José Andrés; Cinesi-Gómez, César; Villén-Villegas, Tomás; Piñera-Salmerón, Pascual; García-Pérez, Bartolo

2016-10-01

To evaluate the correlation between variations in ultrasound-measured diaphragm movement and changes in the arterial partial pressure of carbon dioxide (PCO2) after the start of noninvasive ventilation (NIV). RDescriptive study of a prospective case series comprised of nonconsecutive patients aged 18 years or older with hypercapnic respiratory failure who were placed on NIV in an emergency department. We recorded clinical data, blood gas measurements, and ultrasound measurements of diaphragm movement. Twenty-one patients with a mean (SD) age of 83 (13) years were studied; 11 (52.4%) were women. The mean (SD) range of diaphragm movement and PCO2 values at 4 moments were as follows: 1) at baseline: diaphragm movement, 13.90 (7.7) mm and PCO2, 71.75 (11.4) mm Hg; 2) after 15 minutes on NIV: diaphragm movement, 17.10 (9.1) mm; 3) at 1 hour: diaphragm movement, 22.40 (10.4) mm and PCO2, 63.45 (16.0) mm Hg; and 4) at 3 hours: diaphragm movement, 26.60 (19.5) mm and PCO2, 61.85 (13.0) mm Hg. We detected a statistically significant correlation between the difference in range of diaphragm movement at baseline and at 15 minutes and the decrease in PCO2 after 1 hour of NIV (r=-0.489, P=.035). In patients with hypercapnic respiratory failure, the increase in range of diaphragm movement 15 minutes after starting NIV is associated with a decrease in PCO2 after 1 hour.

Measurement of partial pressures in vacuum technology and vacuum physics

NASA Technical Reports Server (NTRS)

Huber, W. K.

1986-01-01

It is pointed out that the measurement of gaseous pressures of less than 0.0001 torr is based on the ionization of gas atoms and molecules due to collisions with electrons. The particle density is determined in place of the pressure. The ionization cross sections for molecules of various gases are discussed. It is found that the true pressure in a vacuum system cannot be determined with certainty if it is unknown which gas is present. Effects of partial pressure determination on the condition of the vacuum system are discussed together with ion sources, systems of separation, and ion detection.

Partial Molar Volumes of Aqua Ions from First Principles.

PubMed

Wiktor, Julia; Bruneval, Fabien; Pasquarello, Alfredo

2017-08-08

Partial molar volumes of ions in water solution are calculated through pressures obtained from ab initio molecular dynamics simulations. The correct definition of pressure in charged systems subject to periodic boundary conditions requires access to the variation of the electrostatic potential upon a change of volume. We develop a scheme for calculating such a variation in liquid systems by setting up an interface between regions of different density. This also allows us to determine the absolute deformation potentials for the band edges of liquid water. With the properly defined pressures, we obtain partial molar volumes of a series of aqua ions in very good agreement with experimental values.

Densification and Electrical Properties of Zinc Oxide Varistors Microwave-Sintered Under Different Oxygen Partial Pressures

NASA Astrophysics Data System (ADS)

Lin, Cong; Wang, Bo; Xu, Zheng; Peng, Hu

2012-11-01

ZnO varistors were prepared by microwave sintering under different oxygen partial pressures. The temperature profile and the densification behavior in different atmospheres were investigated. It was found that the density of ZnO varistors during sintering was the key factor affecting the absorption of microwave energy. The electrical properties, including the nonlinear properties and capacitance-voltage ( C- V) characteristics, were also carefully studied. The results showed that the oxygen partial pressure has significant effects on the electrical properties of ZnO varistors by changing the concentration of defects through a series of reactions involving oxygen during sintering.

Control of magnetization reversal in oriented strontium ferrite thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roy, Debangsu, E-mail: debangsu@physics.iisc.ernet.in; Anil Kumar, P. S.

2014-02-21

Oriented Strontium Ferrite films with the c axis orientation were deposited with varying oxygen partial pressure on Al{sub 2}O{sub 3}(0001) substrate using Pulsed Laser Deposition technique. The angle dependent magnetic hysteresis, remanent coercivity, and temperature dependent coercivity had been employed to understand the magnetization reversal of these films. It was found that the Strontium Ferrite thin film grown at lower (higher) oxygen partial pressure shows Stoner-Wohlfarth type (Kondorsky like) reversal. The relative importance of pinning and nucleation processes during magnetization reversal is used to explain the type of the magnetization reversal with different oxygen partial pressure during growth.

DEVICE FOR CONTROL OF OXYGEN PARTIAL PRESSURE

DOEpatents

Bradner, H.; Gordon, H.S.

1957-12-24

A device is described that can sense changes in oxygen partial pressure and cause a corresponding mechanical displacement sufficient to actuate meters, valves and similar devices. A piston and cylinder arrangement contains a charge of crystalline metal chelate pellets which have the peculiar property of responding to variations in the oxygen content of the ambient atmosphere by undergoing a change in dimension. A lever system amplifies the relative displacement of the piston in the cylinder, and actuates the controlled valving device. This partial pressure oxygen sensing device is useful in controlled chemical reactions or in respiratory devices such as the oxygen demand meters for high altitude aircraft.

Compressional ULF waves in the outer magnetosphere. 2: A case study of Pc 5 type wave activity

NASA Technical Reports Server (NTRS)

Zhu, Xiaoming; Kivelson, Margaret G.

1994-01-01

In previously published work (Zhu and Kivelson, 1991) the spatial distribution of compressional magnetic pulsations of period 2 - 20 min in the outer magnetosphere was described. In this companion paper, we study some specific compressional events within our data set, seeking to determine the structure of the waves and identifying the wave generation mechanism. We use both the magnetic field and three-dimensional plasma data observed by the International Sun-Earth Explorer (ISEE) 1 and/or 2 spacecraft to characterize eight compressional ultra low frequency (ULF) wave events with frequencies below 8 mHz in the outer magnetosphere. High time resolution plasma data for the event of July 24, 1978, made possible a detailed analysis of the waves. Wave properties specific to the event of July 24, 1978, can be summarized as follows: (1) Partial plasma pressures in the different energy ranges responded to the magnetic field pressure differently. In the low-energy range they oscillated in phase with the magnetic pressure, while oscillations in higher-energy ranges were out-of-phase; (2) Perpendicular wavelengths for the event were determined to be 60,000 and 30,000 km in the radial and azimuthal directions, respectively. Wave properties common to all events can be summarized as follows: (1) Compressional Pc 5 wave activity is correlated with Beta, the ratio of the plasma pressure to the magnetic pressure; the absolute magnitude of the plasma pressure plays a minor role for the wave activity; (2) The magnetic equator is a node of the compressional perturbation of the magnetic field; (3) The criterion for the mirror mode instability is often satisfied near the equator in the outer magnetosphere when the compressional waves are present. We believe these waves are generated by internal magnetohydrodynamic (MHD) instabilities.

Mass separation of deuterium and helium with conventional quadrupole mass spectrometer by using varied ionization energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Yaowei; Hu, Jiansheng, E-mail: hujs@ipp.ac.cn; Wan, Zhao

2016-03-15

Deuterium pressure in deuterium-helium mixture gas is successfully measured by a common quadrupole mass spectrometer (model: RGA200) with a resolution of ∼0.5 atomic mass unit (AMU), by using varied ionization energy together with new developed software and dedicated calibration for RGA200. The new software is developed by using MATLAB with the new functions: electron energy (EE) scanning, deuterium partial pressure measurement, and automatic data saving. RGA200 with new software is calibrated in pure deuterium and pure helium 1.0 × 10{sup −6}–5.0 × 10{sup −2} Pa, and the relation between pressure and ion current of AMU4 under EE = 25 eVmore » and EE = 70 eV is obtained. From the calibration result and RGA200 scanning with varied ionization energy in deuterium and helium mixture gas, both deuterium partial pressures (P{sub D{sub 2}}) and helium partial pressure (P{sub He}) could be obtained. The result shows that deuterium partial pressure could be measured if P{sub D{sub 2}} > 10{sup −6} Pa (limited by ultimate pressure of calibration vessel), and helium pressure could be measured only if P{sub He}/P{sub D{sub 2}} > 0.45, and the measurement error is evaluated as 15%. This method is successfully employed in EAST 2015 summer campaign to monitor deuterium outgassing/desorption during helium discharge cleaning.« less

Synthesis and Characterization of Hexagonal Boron Nitride as a Gate Dielectric

PubMed Central

Jang, Sung Kyu; Youn, Jiyoun; Song, Young Jae; Lee, Sungjoo

2016-01-01

Two different growth modes of large-area hexagonal boron nitride (h-BN) film, a conventional chemical vapor deposition (CVD) growth mode and a high-pressure CVD growth mode, were compared as a function of the precursor partial pressure. Conventional self-limited CVD growth was obtained below a critical partial pressure of the borazine precursor, whereas a thick h-BN layer (thicker than a critical thickness of 10 nm) was grown beyond a critical partial pressure. An interesting coincidence of a critical thickness of 10 nm was identified in both the CVD growth behavior and in the breakdown electric field strength and leakage current mechanism, indicating that the electrical properties of the CVD h-BN film depended significantly on the film growth mode and the resultant film quality. PMID:27458024

UV absorption control of thin film growth

DOEpatents

Biefeld, Robert M.; Hebner, Gregory A.; Killeen, Kevin P.; Zuhoski, Steven P.

1991-01-01

A system for monitoring and controlling the rate of growth of thin films in an atmosphere of reactant gases measures the UV absorbance of the atmosphere and calculates the partial pressure of the gases. The flow of reactant gases is controlled in response to the partial pressure.

NBS: Materials measurements

NASA Technical Reports Server (NTRS)

1980-01-01

Measurements in an Auger spectrometer of surface impurity concentrations on liquid gallium showed that the principle impurities were oxygen and carbon. The impurities showed a tendency to collect into plates or clumps. In Pb rich Pb-Sn off eutectic alloys, macrosegration caused by solutal convection was not reduced by vertical or horizontal fields of 0.1 T, but downward solidification virtually eliminated macrosegration in small diameter samples. Phase assemblages of selected compositions on the joints K(Fe0.5 Si-0.5) O2 -SiO2 and KFeO2 - SiO2 were determined over a large range of oxygen partial pressures and the temperature range 800 C to 1400 C.

Photosynthesis and growth response of almond to increased atmospheric ozone partial pressures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Retzlaff, W.A.; Williams, L.E.; DeJong, T.M.

Uniform nursery stock of five almond cultivars [Prunus dulcis (Mill) D.A. Webb syn. P. amygdalus Batsch, cv. Butte, Carmel, Mission, Nonpareil, and Sonora] propagated on peach (P. domstica L. Batsch.) rootstock were exposed to three different atmospheric ozone (O[sub 3]) partial pressures. The trees were planted in open-top fumigation chambers on 19 Apr. 1989 at the University of California Kearny Agricultural Center located in the San Joaquin Valley of California. Exposures of the trees to three atmospheric O[sub 3] partial pressures lasted from 1 June to 2 Nov. 1989. The mean 12-h [0800-2000 h Pacific Daylight Time (PDT)] O[sub 3]more » partial pressures measured in the open-top chambers during the experimental period were 0.038, 0.060, and 0.112 [mu]Pa Pa[sup [minus]1] O[sub 3] in the charcoal filtered, ambient, and ambient + O[sub 3] treatments, respectively. Leaf net CO[sub 2] assimilation, trunk cross-sectional area growth, and root, trunk, foliage, and total dry weight of Nonpareil were reduced by increased atmospheric O[sub 3] partial pressures. Mission was unaffected by O[sub 3] and Butte, Carmel, and Sonora were intermediate in their responses. Foliage of Nonpareil also abscised prematurely in the ambient and ambient + O[sub 3] treatments. The results indicate that there are almond cultivars that are sensitive to O[sub 3] exposure.« less

Measurements of Pressure Distributions and Force Coefficients in a Squeeze Film Damper. Part 1: Fully Open Ended Configuration

NASA Technical Reports Server (NTRS)

Jung, S. Y.; Sanandres, Luis A.; Vance, J. M.

1991-01-01

Measurements of pressure distributions and force coefficients were carried out in two types of squeeze film dampers, executing a circular centered orbit, an open-ended configuration, and a partially sealed one, in order to investigate the effect of fluid inertia and cavitation on pressure distributions and force coefficients. Dynamic pressure measurements were carried out for two orbit radii, epsilon 0.5 and 0.8. It was found that the partially sealed configuration was less influenced by fluid inertia than the open ended configuration.

Gas pressure and electron density at the level of the active zone of hollow cathode arc discharges

NASA Technical Reports Server (NTRS)

Minoo, M. H.

1984-01-01

A model for the longitudinal variations of the partial pressures of electrons, ions, and neutral particles is proposed as a result of an experimental study of pressure variations at the level of the active zone as a function of the various discharge parameters of a hollow cathode arc. The cathode region where the temperature passes through its maximum is called active zone. The proposed model embodies the very important variations which the partial electron and neutral particles pressures undergo at the level of the active zone.

One-dimensional Ar-SF{sub 6} hydromodel at low-pressure in e-beam generated plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrov, George M., E-mail: george.petrov@nrl.navy.mil; Boris, David R.; Petrova, Tzvetelina B.

2016-03-15

A one-dimensional steady-state hydrodynamic model of electron beam generated plasmas produced in Ar-SF{sub 6} mixtures at low pressure in a constant magnetic field was developed. Simulations were performed for a range of SF{sub 6} partial pressures at constant 30 mTorr total gas pressure to determine the spatial distribution of species densities and fluxes. With the addition of small amount of SF{sub 6} (∼1%), the confining electrostatic field sharply decreases with respect to the pure argon case. This effect is due to the applied magnetic field inhibiting electron diffusion. The hallmark of electronegative discharge plasmas, positive ion—negative ion core and positivemore » ion—electron edge, was not observed. Instead, a plasma with large electronegativity (∼100) is formed throughout the volume, and only a small fraction (≈30%) of the parent SF{sub 6} molecules were dissociated to F{sub 2}, SF{sub 2}, and SF{sub 4}. Importantly, F radical densities were found to be very low, on the order of the ion density. Model predictions for the electron density, ion density, and plasma electronegativity are in good agreement with experimental data over the entire range of SF{sub 6} concentrations investigated.« less

Solubility of oxygen in a seawater medium in equilibrium with a high-pressure oxy-helium atmosphere.

PubMed

Taylor, C D

1979-06-01

The molar oxygen concentration in a seawater medium in equilibrium with a high-pressure oxygen-helium atmosphere was measured directly in pressurized subsamples, using a modified version of the Winkler oxygen analysis. At a partial pressure of oxygen of 1 atm or less, its concentration in the aqueous phase was adequately described by Henry's Law at total pressures up to 600 atm. This phenomenon, which permits a straightforward determination of dissolved oxygen within hyperbaric systems, resulted from pressure-induced compensatory alterations in the Henry's Law variables rather than from a true obedience to the Ideal Gas Law. If the partial pressure of a gas contributes significantly to the hydrostatic pressure, Henry's Law is no longer adequate for determining its solubility within the compressed medium.

Randomized trial of low versus high carbon dioxide insufflation pressures in posterior retroperitoneoscopic adrenalectomy.

PubMed

Fraser, Sheila; Norlén, Olov; Bender, Kyle; Davidson, Joanne; Bajenov, Sonya; Fahey, David; Li, Shawn; Sidhu, Stan; Sywak, Mark

2018-05-01

Posterior retroperitoneoscopic adrenalectomy has gained widespread acceptance for the removal of benign adrenal tumors. Higher insufflation pressures using carbon dioxide (CO 2 ) are required, although the ideal starting pressure is unclear. This prospective, randomized, single-blinded, study aims to compare physiologic differences with 2 different CO 2 insufflation pressures during posterior retroperitoneoscopic adrenalectomy. Participants were randomly assigned to a starting insufflation pressure of 20 mm Hg (low pressure) or 25 mm Hg (high pressure). The primary outcome measure was partial pressure of arterial CO 2 at 60 minutes. Secondary outcomes included end-tidal CO 2 , arterial pH, blood pressure, and peak airway pressure. Breaches of protocol to change insufflation pressure were permitted if required and were recorded. A prospective randomized trial including 31 patients (low pressure: n = 16; high pressure: n = 15) was undertaken. At 60 minutes, the high pressure group had greater mean partial pressure of arterial CO 2 (64 vs 50 mm Hg, P = .003) and end-tidal CO 2 (54 vs 45 mm Hg, P = .008) and a lesser pH (7.21 vs 7.29, P = .0005). There were no significant differences in base excess, peak airway pressure, operative time, or duration of hospital stay. Clinically indicated protocol breaches were more common in the low pressure than the high pressure group (8 vs 3, P = .03). In posterior retroperitoneoscopic adrenalectomy, greater insufflation pressures are associated with greater partial pressure of arterial CO 2 and end-tidal CO 2 and lesser pH at 60 minutes, be significant. Commencing with lesser CO 2 insufflation pressures decreases intraoperative acidosis. Copyright © 2017 Elsevier Inc. All rights reserved.

Methods for producing silicon carbide fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garnier, John E.; Griffith, George W.

Methods of producing silicon carbide fibers. The method comprises reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500.degree. C. to approximately 2000.degree. C. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01.times.10.sup.2 Pascal to produce continuous alpha silicon carbide fibers. Continuous alpha silicon carbide fibers and articles formed from the continuous alpha silicon carbide fibers are also disclosed.

Silicon carbide fibers and articles including same

DOEpatents

Garnier, John E; Griffith, George W

2015-01-27

Methods of producing silicon carbide fibers. The method comprises reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500.degree. C. to approximately 2000.degree. C. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01.times.10.sup.2 Pascal to produce continuous alpha silicon carbide fibers. Continuous alpha silicon carbide fibers and articles formed from the continuous alpha silicon carbide fibers are also disclosed.

Bionanomaterials and Bioinspired Nanostructures for Selective Vapor Sensing

DTIC Science & Technology

2013-04-03

with the current baseline shown with yellow points. DNA sequence: 5′ GAG TCT GTG GAG GAG GTA GTC 3′. Green and black arrows in panels a–c show the...SWCNT transducer to TNT (red circles), RDX ( gray triangles), and HPT (black squares). Blue arrows in panels b and c show introduction of analyte vapors...increasing partial pressure ranging from 0 to 0.07 P/P0. Vapor concentrations are 0 ( gray dashed lines), 0.02 (red curves), 0.04 ( gold curves), and 0.07

The teaching of fixed partial dentures in undergraduate dental schools in Ireland and the United Kingdom.

PubMed

Lynch, C D; Singhrao, H; Addy, L D; Gilmour, A S M

2010-12-01

All areas of the practice of dentistry are evolving at a considerable pace. One area in particular which has seen a rapid revolution is the oral rehabilitation of partially dentate adults. The aim of this study was to describe the contemporary teaching of fixed partial dentures (FPDs) in dental schools in Ireland and the United Kingdom. An online questionnaire which sought information in relation to the current teaching of FPDs was developed and distributed to 15 Irish and UK dental schools with undergraduate teaching programmes in Spring 2009. Responses were received from 12 schools (response rate=80%). All schools offer teaching programmes in relation to FPDs. The number of hours devoted to pre-clinical/phantom head teaching of FPDs ranged from 3 to 42h (mean: 16h). The staff/student ratio for pre-clinical teaching courses in FPDs ranged from 1:6 to 1:18 (mode: 1:12). Cantilever resin-retained FPDs were the most popular type of FPD provided clinically (average=0·83 per school; range=1-2). Five schools (42%) report that they have requirements (e.g. targets, quotas, competencies) which students must complete prior to graduation in relation to FPDs. Fixed partial dentures form an important part of the undergraduate teaching programme in UK and Irish dental schools. While this teaching is subjected to contemporary pressures such as lack of curriculum time and a lack of available clinical facilities and teachers, there is evidence that teaching programmes in this area are evolving and are sensitive to current clinical practice trends and evidence-based practice. © 2010 Blackwell Publishing Ltd.

Modeling the exhumation path of partially melted ultrahigh-pressure metapelites, North-East Greenland Caledonides

NASA Astrophysics Data System (ADS)

Lang, Helen M.; Gilotti, Jane A.

2015-06-01

Pseudosection modeling constrains the pressure-temperature (P-T) exhumation path of partially melted ultrahigh-pressure (UHP) metapelites exposed in the North-East Greenland UHP terrane. A robust peak P and T estimate of 3.6 GPa and 970 °C based on mineral assemblages in nearby kyanite eclogites is the starting point for the P-T path. Although the peak assemblage for the metapelite is not preserved, the calculated modeled peak assemblage contained substantial clinopyroxene, garnet, phengite, K-feldspar and coesite with minor kyanite and rutile. Combining the pseudosection and observed textures, the decompression path crosses the coesite-quartz transition before reaching the dry phengite dehydration melting reaction where phengite is abruptly consumed. In the range of 2.5 to 2.2 GPa, clinopyroxene is completely consumed and garnet grows to its maximum volume and grossular content, matching the high grossular rims of relict megacrysts. Plagioclase joins the assemblage and the pseudosection predicts up to 12-13 vol.% melt in the supersolidus assemblage, which contained garnet, liquid, K-feldspar, plagioclase, kyanite, quartz and rutile. At this stage, the steep decompression path flattened out and became nearly isobaric. The melt crystallization assemblage that formed when the path crossed the solidus with decreasing temperature contains phengite, garnet, biotite, 2 feldspars, kyanite, quartz and rutile. Therefore, the path must have intersected the solidus at approximately 1.2 GPa, 825 °C. The pseudosection predicts that garnet is consumed on the cooling path, but little evidence of late garnet consumption or other retrograde effects is observed. This may be due to partial melt loss from the rock. Isochemical PT-n and PT-X sections calculated along the P-T path display changes in mineral assemblage and composition that are consistent with preserved assemblages.

Pressure dependence of the electro-optic response function in partially exposed polymer dispersed ferroelectric liquid crystals

NASA Technical Reports Server (NTRS)

Parmar, D. S.; Holmes, H. K.

1993-01-01

Ferroelectric liquid crystals in a new configuration, termed partially exposed polymer dispersed ferroelectric liquid crystal (PEPDFLC), respond to external pressures and demonstrate pressure-induced electro-optic switching response. When the PEPDFLC thin film is sandwiched between two transparent conducting electrodes, one a glass plate and the other a flexible sheet such as polyvenylidene fluoride, the switching characteristics of the thin film are a function of the pressure applied to the flexible transparent electrode and the bias voltage across the electrodes. Response time measurements reveal a linear dependence of the change in electric field with external pressure.

Delayed pressure urticaria: response to treatment with sulfasalazine in a case series of seventeen patients.

PubMed

Swerlick, Robert A; Puar, Neha

2015-01-01

We retrospectively identified 17 patients with delayed pressure urticaria (DPU), diagnosed by history and confirmed with provocative pressure testing. The average age in the cohort was 42.6 years with 10 women and seven men. The mean duration of disease before diagnosis was 19.7 months (range, 1-60 months). The diagnosis of DPU was not included in the differential diagnosis of referring physicians and was not a diagnostic consideration in any of seven biopsies obtained. None of the patients responded adequately to treatment with antihistamines, but all 17 responded transiently when treated with either oral or intramuscular steroids. Eleven patients experienced complete or near complete resolution of DPU with treatment with sulfasalazine (SZ). Four patients had a partial response while two were unable to continue therapy because of drug intolerance. SZ appears to be a low cost and effective treatment for DPU. © 2015 Wiley Periodicals, Inc.

Effects of bleed-hole geometry and plenum pressure on three-dimensional shock-wave/boundary-layer/bleed interactions

NASA Technical Reports Server (NTRS)

Chyu, Wei J.; Rimlinger, Mark J.; Shih, Tom I.-P.

1993-01-01

A numerical study was performed to investigate 3D shock-wave/boundary-layer interactions on a flat plate with bleed through one or more circular holes that vent into a plenum. This study was focused on how bleed-hole geometry and pressure ratio across bleed holes affect the bleed rate and the physics of the flow in the vicinity of the holes. The aspects of the bleed-hole geometry investigated include angle of bleed hole and the number of bleed holes. The plenum/freestream pressure ratios investigated range from 0.3 to 1.7. This study is based on the ensemble-averaged, 'full compressible' Navier-Stokes (N-S) equations closed by the Baldwin-Lomax algebraic turbulence model. Solutions to the ensemble-averaged N-S equations were obtained by an implicit finite-volume method using the partially-split, two-factored algorithm of Steger on an overlapping Chimera grid.

Molecular Packing of Functionalized Fluorinated Lipids in Langmuir Monolayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landsberg, Michael J.; Ruggles, Jeremy L.; Hussein, Waleed M.

2012-01-20

Fluorinated amphipaths are a fascinating class of compounds, which, despite significant challenges associated with their syntheses, have found use across a number of areas of biotechnology. Applications range from the in vitro stabilization of membrane proteins to the development of enhanced stability intravenous drug and gene delivery systems. More recently, monolayer-forming fluorinated lipids have found use in the 2D crystallization of detergent-solubilized hydrophobic or partially hydrophobic proteins at the air-water interface. In this study, we investigate the surface properties of a novel suite of monolayer forming, partially fluorinated lipids. These modular lipid structures contain a densely fluorinated insertion in themore » hydrocarbon tail and a synthetically modifiable headgroup. Analyses of surface-pressure area isotherms and X-ray reflectometry profiles reveal that the lipids spread into fluid monolayers and are more compressible than their non-fluorinated counterparts. Furthermore, the data support a model whereby the partially fluorinated chains of the lipid tails form a film which is fundamentally incompatible with detergents and other destabilizing amphipaths.« less

Geometry of α-Cr2O3(0001) as a Function of H2O Partial Pressure

PubMed Central

2015-01-01

Surface X-ray diffraction has been employed to elucidate the surface structure of α-Cr2O3(0001) as a function of water partial pressure at room temperature. In ultra high vacuum, following exposure to ∼2000 Langmuir of H2O, the surface is found to be terminated by a partially occupied double layer of chromium atoms. No evidence of adsorbed OH/H2O is found, which is likely due to either adsorption at minority sites, or X-ray induced desorption. At a water partial pressure of ∼30 mbar, a single OH/H2O species is found to be bound atop each surface Cr atom. This adsorption geometry does not agree with that predicted by ab initio calculations, which may be a result of some differences between the experimental conditions and those modeled. PMID:26877825

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. 868.1150 Section 868.1150 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... “Class II Special Controls Guidance Document: Indwelling Blood Gas Analyzers; Final Guidance for Industry...

Classifying Acute Respiratory Distress Syndrome Severity: Correcting the Arterial Oxygen Partial Pressure to Fractional Inspired Oxygen at Altitude.

PubMed

Pérez-Padilla, Rogelio; Hernández-Cárdenas, Carmen Margarita; Lugo-Goytia, Gustavo

2016-01-01

In the well-known Berlin definition of acute respiratory distress syndrome (ARDS), there is a recommended adjustment for arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FIO2) at altitude, but without a reference as to how it was derived.

Solubility of carbon dioxide in aqueous mixtures of alkanolamines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dawodu, O.F.; Meisen, A.

1994-07-01

The solubility of CO[sub 2] in water + N-methyldiethanolamine + monoethanolamine (MDEA + MEA) and water + N-methyldiethanolamine + diethanolamine (MDEA + DEA) are reported at two compositions of 3.4 M MDEA + 0.8 M MEA or DEA and 2.1 M MDEA + 2.1 M MEA or DEA at temperatures from 70 to 180 C and CO[sub 2] partial pressures from 100 to 3,850 kPa. The solubility of CO[sub 2] in the blends decreased with an increase in temperature but increased with an increase in CO[sub 2] partial pressure. At low partial pressures of CO[sub 2] and the same totalmore » amine concentration, the equilibrium CO[sub 2] loadings were in the order MDEA + MEA > MDEA + DEA > MDEA. However, at high CO[sub 2] partial pressures, the equilibrium CO[sub 2] loadings in the MDEA solutions were higher than those of the MDEA + MEA and MDEA + DEA blends of equal molar strengths due to the stoichiometric loading limitations of MEA and DEA. The nonadditivity of the equilibrium loadings for single amine systems highlights the need for independent measurements on amine blends.« less

Method for sensing and measuring a concentration or partial pressure of a reactant used in a redox reaction

DOEpatents

Findl, E.

1984-12-21

A method for sensing or measuring the partial pressure or concentration of an electroactive species used in conjunction with an electrolyte, the method being characterized by providing a constant current between an anode and a cathode of an electrolyte-containing cell, while measuring changes in voltage that occur between either the anode and cathode or between a reference electrode and one of the main electrodes of the cell, thereby to determine the concentration or partial pressure of the electro-active species as a function of said measured voltage changes. The method of the invention can be practiced using either a cell having only an anode and a cathode, or using a cell having an anode and a cathode in combination with a reference electrode. Accurate measurements of small concentrations or partial pressures of electro-active species are obtainable with the method of the invention, by using constant currents of only a few microamperes between the anode and cathode of the cell, while the concentration-determining voltage is measured.

Oxidation of C/SiC Composites at Reduced Oxygen Partial Pressures

NASA Technical Reports Server (NTRS)

Opila, E. J.; Serra, J. L.

2007-01-01

T-300 carbon fibers and T-300 carbon fiber reinforced silicon carbide composites (C/SiC) were oxidized in flowing reduced oxygen partial pressure environments at a total pressure of one atmosphere (0.5 atm O2, 0.05 atm O2 and 0.005 atm O2, balance argon). Experiments were conducted at four temperatures (816deg, 1149deg, 1343deg, and 1538 C). The oxidation kinetics were monitored using thermogravimetric analysis. T-300 fibers were oxidized to completion for times between 0.6 and 90 h. Results indicated that fiber oxidation kinetics were gas phase diffusion controlled. Oxidation rates had an oxygen partial pressure dependence with a power law exponent close to one. In addition, oxidation rates were only weakly dependent on temperature. The C/SiC coupon oxidation kinetics showed some variability, attributed to differences in the number and width of cracks in the SiC seal coat. In general, weight losses were observed indicating oxidation of the carbon fibers dominated the oxidation behavior. Low temperatures and high oxygen pressures resulted in the most rapid consumption of the carbon fibers. At higher temperatures, the lower oxidation rates were primarily attributed to crack closure due to SiC thermal expansion, rather than oxidation of SiC since these reduced rates were observed even at the lowest oxygen partial pressures where SiC oxidation is minimal.

Pressure effects on the structure, kinetic, and thermodynamic properties of heat-induced aggregation of protein studied by FT-IR spectroscopy

NASA Astrophysics Data System (ADS)

Taniguchi, Y.; Okuno, A.; Kato, M.

2010-03-01

Pressure can retrain the heat-induced aggregation and dissociate the heat-induced aggregates. We observed the aggregation-preventing pressure effect and the aggregates-dissociating pressure effect to characterize the heat-induced aggregation of equine serum albumin (ESA) by FT-IR spectroscopy. The results suggest the α-helical structure collapses at the beginning of heat-induced aggregation through the swollen structure, and then the rearrangement of structure to the intermolecular β-sheet takes place through partially unfolded structure. We determined the activation volume for the heat-induced aggregation (ΔV# = +93 ml/mol) and the partial molar volume difference between native state and heat-induced aggregates (ΔV=+32 ml/mol). This positive partial molar volume difference suggests that the heat-induced aggregates have larger internal voids than the native structure. Moreover, the positive volume change implies that the formation of the intermolecular β-sheet is unfavorable under high pressure.

Optimizing the physical ergonomics indices for the use of partial pressure suits.

PubMed

Ding, Li; Li, Xianxue; Hedge, Alan; Hu, Huimin; Feathers, David; Qin, Zhifeng; Xiao, Huajun; Xue, Lihao; Zhou, Qianxiang

2015-03-01

This study developed an ergonomic evaluation system for the design of high-altitude partial pressure suits (PPSs). A total of twenty-one Chinese males participated in the experiment which tested three types of ergonomics indices (manipulative mission, operational reach and operational strength) were studied using a three-dimensional video-based motion capture system, a target-pointing board, a hand dynamometer, and a step-tread apparatus. In total, 36 ergonomics indices were evaluated and optimized using regression and fitting analysis. Some indices that were found to be linearly related and redundant were removed from the study. An optimal ergonomics index system was established that can be used to conveniently and quickly evaluate the performance of different pressurized/non-pressurized suit designs. The resulting ergonomics index system will provide a theoretical basis and practical guidance for mission planners, suit designers and engineers to design equipment for human use, and to aid in assessing partial pressure suits. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Analyzing the dependence of oxygen incorporation current density on overpotential and oxygen partial pressure in mixed conducting oxide electrodes.

PubMed

Guan, Zixuan; Chen, Di; Chueh, William C

2017-08-30

The oxygen incorporation reaction, which involves the transformation of an oxygen gas molecule to two lattice oxygen ions in a mixed ionic and electronic conducting solid, is a ubiquitous and fundamental reaction in solid-state electrochemistry. To understand the reaction pathway and to identify the rate-determining step, near-equilibrium measurements have been employed to quantify the exchange coefficients as a function of oxygen partial pressure and temperature. However, because the exchange coefficient contains contributions from both forward and reverse reaction rate constants and depends on both oxygen partial pressure and oxygen fugacity in the solid, unique and definitive mechanistic assessment has been challenging. In this work, we derive a current density equation as a function of both oxygen partial pressure and overpotential, and consider both near and far from equilibrium limits. Rather than considering specific reaction pathways, we generalize the multi-step oxygen incorporation reaction into the rate-determining step, preceding and following quasi-equilibrium steps, and consider the number of oxygen ions and electrons involved in each. By evaluating the dependence of current density on oxygen partial pressure and overpotential separately, one obtains the reaction orders for oxygen gas molecules and for solid-state species in the electrode. We simulated the oxygen incorporation current density-overpotential curves for praseodymium-doped ceria for various candidate rate-determining steps. This work highlights a promising method for studying the exchange kinetics far away from equilibrium.

Efficient absorption of SO2 with low-partial pressures by environmentally benign functional deep eutectic solvents.

PubMed

Zhang, Kai; Ren, Shuhang; Hou, Yucui; Wu, Weize

2017-02-15

Sulfur dioxide (SO 2 ) emitted from the burning of fossil fuels is one of the main air contaminants. In this work, we found that environmentally benign solvents, deep eutectic solvents (DESs) could be designed with a function to absorb low-partial pressure SO 2 from simulated flue gas. Two kinds of biodegradable functional DESs based on betaine (Bet) and l-carnitine (L-car) as hydrogen bond accepters (HBA) and ethylene glycol (EG) as a hydrogen bond donor (HBD) were prepared with mole ratios of HBA to HBD from 1:3 to 1:5, and they were investigated to absorb SO 2 with different partial pressures at various temperatures. The results showed that the two DESs could absorb low-partial pressure SO 2 efficiently. SO 2 absorption capacities of the DESs with HBA/HBD mole ratio of 1:3 were 0.332mol SO 2 /mol HBA for Bet+EG DES and 0.820mol SO 2 /mol HBA for L-car+EG DES at 40°C with a SO 2 partial pressure of 0.02atm. In addition, the regeneration experiments demonstrated that the absorption capacities of DESs did not change after five absorption and desorption cycles. Furthermore, the absorption mechanism of SO 2 by DESs was studied by FT-IR, 1 H NMR and 13 C NMR spectra. It was found that there are strong acid-base interactions between SO 2 and -COO - on HBA. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of oxygen on responses to heating in two lizard species sampled along an elevational gradient.

PubMed

DuBois, P Mason; Shea, Tanner K; Claunch, Natalie M; Taylor, Emily N

2017-08-01

Thermal tolerance is an important variable in predictive models about the effects of global climate change on species distributions, yet the physiological mechanisms responsible for reduced performance at high temperatures in air-breathing vertebrates are not clear. We conducted an experiment to examine how oxygen affects three variables exhibited by ectotherms as they heat-gaping threshold, panting threshold, and loss of righting response (the latter indicating the critical thermal maximum)-in two lizard species along an elevational (and therefore environmental oxygen partial pressure) gradient. Oxygen partial pressure did not impact these variables in either species. We also exposed lizards at each elevation to severely hypoxic gas to evaluate their responses to hypoxia. Severely low oxygen partial pressure treatments significantly reduced the gaping threshold, panting threshold, and critical thermal maximum. Further, under these extreme hypoxic conditions, these variables were strongly and positively related to partial pressure of oxygen. In an elevation where both species overlapped, the thermal tolerance of the high elevation species was less affected by hypoxia than that of the low elevation species, suggesting the high elevation species may be adapted to lower oxygen partial pressures. In the high elevation species, female lizards had higher thermal tolerance than males. Our data suggest that oxygen impacts the thermal tolerance of lizards, but only under severely hypoxic conditions, possibly as a result of hypoxia-induced anapyrexia. Copyright © 2017. Published by Elsevier Ltd.

Oxygen vacancy induced phase formation and room temperature ferromagnetism in undoped and Co-doped TiO2 thin films

NASA Astrophysics Data System (ADS)

Mohanty, P.; Mishra, N. C.; Choudhary, R. J.; Banerjee, A.; Shripathi, T.; Lalla, N. P.; Annapoorni, S.; Rath, Chandana

2012-08-01

TiO2 and Co-doped TiO2 (CTO) thin films deposited at various oxygen partial pressures by pulsed laser deposition exhibit room temperature ferromagnetism (RTFM) independent of their phase. Films deposited at 0.1 mTorr oxygen partial pressure show a complete rutile phase confirmed from glancing angle x-ray diffraction and Raman spectroscopy. At the highest oxygen partial pressure, i.e. 300 mTorr, although the TiO2 film shows a complete anatase phase, a small peak corresponding to the rutile phase along with the anatase phase is identified in the case of CTO film. An increase in O to Ti/(Ti+Co) ratio with increase in oxygen partial pressure is observed from Rutherford backscattering spectroscopy. It is revealed from x-ray photoelectron spectroscopy (XPS) that oxygen vacancies are found to be higher in the CTO film than TiO2, while the valency of cobalt remains in the +2 state. Therefore, the CTO film deposited at 300 mTorr does not show a complete anatase phase unlike the TiO2 film deposited at the same partial pressure. We conclude that RTFM in both films is not due to impurities/contaminants, as confirmed from XPS depth profiling and cross-sectional transmission electron microscopy (TEM), but due to oxygen vacancies. The magnitude of moment, however, depends not only on the phase of TiO2 but also on the crystallinity of the films.

Reproducing early Martian atmospheric carbon dioxide partial pressure by modeling the formation of Mg-Fe-Ca carbonate identified in the Comanche rock outcrops on Mars

NASA Astrophysics Data System (ADS)

Berk, Wolfgang; Fu, Yunjiao; Ilger, Jan-Michael

2012-10-01

The well defined composition of the Comanche rock's carbonate (Magnesite0.62Siderite0.25Calcite0.11Rhodochrosite0.02) and its host rock's composition, dominated by Mg-rich olivine, enable us to reproduce the atmospheric CO2partial pressure that may have triggered the formation of these carbonates. Hydrogeochemical one-dimensional transport modeling reveals that similar aqueous rock alteration conditions (including CO2partial pressure) may have led to the formation of Mg-Fe-Ca carbonate identified in the Comanche rock outcrops (Gusev Crater) and also in the ultramafic rocks exposed in the Nili Fossae region. Hydrogeochemical conditions enabling the formation of Mg-rich solid solution carbonate result from equilibrium species distributions involving (1) ultramafic rocks (ca. 32 wt% olivine; Fo0.72Fa0.28), (2) pure water, and (3) CO2partial pressures of ca. 0.5 to 2.0 bar at water-to-rock ratios of ca. 500 molH2O mol-1rock and ca. 5°C (278 K). Our modeled carbonate composition (Magnesite0.64Siderite0.28Calcite0.08) matches the measured composition of carbonates preserved in the Comanche rocks. Considerably different carbonate compositions are achieved at (1) higher temperature (85°C), (2) water-to-rock ratios considerably higher and lower than 500 mol mol-1 and (3) CO2partial pressures differing from 1.0 bar in the model set up. The Comanche rocks, hosting the carbonate, may have been subjected to long-lasting (>104 to 105 years) aqueous alteration processes triggered by atmospheric CO2partial pressures of ca. 1.0 bar at low temperature. Their outcrop may represent a fragment of the upper layers of an altered olivine-rich rock column, which is characterized by newly formed Mg-Fe-Ca solid solution carbonate, and phyllosilicate-rich alteration assemblages within deeper (unexposed) units.

Oxygen-Partial-Pressure Sensor for Aircraft Oxygen Mask

NASA Technical Reports Server (NTRS)

Kelly, Mark; Pettit, Donald

2003-01-01

A device that generates an alarm when the partial pressure of oxygen decreases to less than a preset level has been developed to help prevent hypoxia in a pilot or other crewmember of a military or other high-performance aircraft. Loss of oxygen partial pressure can be caused by poor fit of the mask or failure of a hose or other component of an oxygen distribution system. The deleterious physical and mental effects of hypoxia cause the loss of a military aircraft and crew every few years. The device is installed in the crewmember s oxygen mask and is powered via communication wiring already present in all such oxygen masks. The device (see figure) includes an electrochemical sensor, the output potential of which is proportional to the partial pressure of oxygen. The output of the sensor is amplified and fed to the input of a comparator circuit. A reference potential that corresponds to the amplified sensor output at the alarm oxygen-partial-pressure level is fed to the second input of the comparator. When the sensed partial pressure of oxygen falls below the minimum acceptable level, the output of the comparator goes from the low state (a few millivolts) to the high state (near the supply potential, which is typically 6.8 V for microphone power). The switching of the comparator output to the high state triggers a tactile alarm in the form of a vibration in the mask, generated by a small 1.3-Vdc pager motor spinning an eccentric mass at a rate between 8,000 and 10,000 rpm. The sensation of the mask vibrating against the crewmember s nose is very effective at alerting the crewmember, who may already be groggy from hypoxia and is immersed in an environment that is saturated with visual cues and sounds. Indeed, the sensation is one of rudeness, but such rudeness could be what is needed to stimulate the crewmember to take corrective action in a life-threatening situation.

Carbon Monoxide, Hydrogen, and Formate Metabolism during Methanogenesis from Acetate by Thermophilic Cultures of Methanosarcina and Methanothrix Strains.

PubMed

Zinder, S H; Anguish, T

1992-10-01

CO and H(2) have been implicated in methanogenesis from acetate, but it is unclear whether they are directly involved in methanogenesis or electron transfer in acetotrophic methanogens. We compared metabolism of H(2), CO, and formate by cultures of the thermophilic acetotrophic methanogens Methanosarcina thermophila TM-1 and Methanothrix sp. strain CALS-1. M. thermophila accumulated H(2) to partial pressures of 40 to 70 Pa (1 Pa = 0.987 x 10 atm), as has been previously reported for this and other Methanosarcina cultures. In contrast, Methanothrix sp. strain CALS-1 accumulated H(2) to maximum partial pressures near 1 Pa. Growing cultures of Methanothrix sp. strain CALS-1 initially accumulated CO, which reached partial pressures near 0.6 Pa (some CO came from the rubber stopper) during the middle of methanogenesis; this was followed by a decrease in CO partial pressures to less than 0.01 Pa by the end of methanogenesis. Accumulation or consumption of CO by cultures of M. thermophila growing on acetate was not detected. Late-exponential-phase cultures of Methanothrix sp. strain CALS-1, in which the CO partial pressure was decreased by flushing with N(2)-CO(2), accumulated CO to 0.16 Pa, whereas cultures to which ca. 0.5 Pa of CO was added consumed CO until it reached this partial pressure. Cyanide (1 mM) blocked CO consumption but not production. High partial pressures of H(2) (40 kPa) inhibited methanogenesis from acetate by M. thermophila but not by Methanothrix sp. strain CALS-1, and 2 kPa of CO was not inhibitory to M. thermophila but was inhibitory to Methanothrix sp. strain CALS-1. Levels of CO dehydrogenase, hydrogenase, and formate dehydrogenase in Methanothrix sp. strain CALS-1 were 9.1, 0.045, and 5.8 mumol of viologen reduced min mg of protein. These results suggest that CO plays a role in Methanothrix sp. strain CALS-1 similar to that of H(2) in M. thermophila and are consistent with the conclusion that CO is an intermediate in a catabolic or anabolic pathway in Methanothrix sp. strain CALS-1; however, they could also be explained by passive equilibration of CO with a metabolic intermediate.

Carbon Monoxide, Hydrogen, and Formate Metabolism during Methanogenesis from Acetate by Thermophilic Cultures of Methanosarcina and Methanothrix Strains

PubMed Central

Zinder, S. H.; Anguish, T.

1992-01-01

CO and H2 have been implicated in methanogenesis from acetate, but it is unclear whether they are directly involved in methanogenesis or electron transfer in acetotrophic methanogens. We compared metabolism of H2, CO, and formate by cultures of the thermophilic acetotrophic methanogens Methanosarcina thermophila TM-1 and Methanothrix sp. strain CALS-1. M. thermophila accumulated H2 to partial pressures of 40 to 70 Pa (1 Pa = 0.987 × 10-5 atm), as has been previously reported for this and other Methanosarcina cultures. In contrast, Methanothrix sp. strain CALS-1 accumulated H2 to maximum partial pressures near 1 Pa. Growing cultures of Methanothrix sp. strain CALS-1 initially accumulated CO, which reached partial pressures near 0.6 Pa (some CO came from the rubber stopper) during the middle of methanogenesis; this was followed by a decrease in CO partial pressures to less than 0.01 Pa by the end of methanogenesis. Accumulation or consumption of CO by cultures of M. thermophila growing on acetate was not detected. Late-exponential-phase cultures of Methanothrix sp. strain CALS-1, in which the CO partial pressure was decreased by flushing with N2-CO2, accumulated CO to 0.16 Pa, whereas cultures to which ca. 0.5 Pa of CO was added consumed CO until it reached this partial pressure. Cyanide (1 mM) blocked CO consumption but not production. High partial pressures of H2 (40 kPa) inhibited methanogenesis from acetate by M. thermophila but not by Methanothrix sp. strain CALS-1, and 2 kPa of CO was not inhibitory to M. thermophila but was inhibitory to Methanothrix sp. strain CALS-1. Levels of CO dehydrogenase, hydrogenase, and formate dehydrogenase in Methanothrix sp. strain CALS-1 were 9.1, 0.045, and 5.8 μmol of viologen reduced min-1 mg of protein-1. These results suggest that CO plays a role in Methanothrix sp. strain CALS-1 similar to that of H2 in M. thermophila and are consistent with the conclusion that CO is an intermediate in a catabolic or anabolic pathway in Methanothrix sp. strain CALS-1; however, they could also be explained by passive equilibration of CO with a metabolic intermediate. PMID:16348788

Spatial and Temporal Variations in the Partial Pressure and Emission of CO2 and CH4 in and Amazon Floodplain Lake

NASA Astrophysics Data System (ADS)

Forsberg, B. R.; Amaral, J. H.; Barbosa, P.; Kasper, D.; MacIntyre, S.; Cortes, A.; Sarmento, H.; Borges, A. V.; Melack, J. M.; Farjalla, V.

2015-12-01

The Amazon floodplain contains a variety of wetland environments which contribute CO2 and CH4 to the regional and global atmospheres. The partial pressure and emission of these greenhouse gases (GHGs) varies: 1) between habitats, 2) seasonally, as the characteristics these habitats changes and 3) diurnally, in response to diurnal stratification. In this study, we investigated the combined influence of these factors on the partial pressure and emission of GHGs in Lago Janauacá, a central Amazon floodplain lake (3o23' S; 60o18' O). All measurements were made between August of 2014 and April of 2015 at two different sites and in three distinct habitats: open water, flooded forest, flooded macrophytes. Concentrations of CO2 and CH4 in air were measured continuously with a cavity enhanced absorption spectrometer, Los Gatos Research´s Ultraportable Greenhouse Gas Analyzer (UGGA). Vertical profiles o pCO2 and pCH4 were measured using the UGGA connected to an electric pump and equilibrator. Diffusive surface emissions were estimated with the UGGA connected to a static floating chamber. To investigate the influence of vertical stratification and mixing on GHG partial pressure and emissions, a meteorological station and submersible sensor chain were deployed at each site. Meteorological sensors included wind speed and direction. The submersible chains included thermistors and oxygen sensors. Depth profiles of partial pressure and diffusive emissions for both CO2 and CH4 varied diurnally, seasonally and between habitats. Both pCO2 and pCH4 were consistently higher in bottom than surface waters with the largest differences occurring at high water when thermal stratification was most stable. Methane emissions and partial pressures were highest at low water while pCO2 and CO2 fluxes were highest during high water periods, with 35% of CO2 fluxes at low water being negative. The highest average surface value of pCO2 (5491 μatm), encountered during rising water, was ~3 times higher than that encountered at low water (1708 μatm). Partial pressures and emissions of both CO2 and CH4 were greatest in open water habitats and consistently higher at night. These patterns reflected the higher levels of wind driven mixing and turbulence in open water environments and higher convective mixing at night which promoted diffusive emission.

Interpretation of trace element and isotope features of basalts: relevance of field relations, petrology, major element data, phase equilibria, and magma chamber modeling in basalt petrogenesis

NASA Astrophysics Data System (ADS)

O'Hara, M. J.; Herzberg, C.

2002-06-01

The concentrations and ratios of the major elements determine the physical properties and the phase equilibria behavior of peridotites and basalts in response to the changing energy contents of the systems. The behavior of the trace elements and isotopic features are influenced in their turn by the phase equilibria, by the physical character of the partial melting and partial crystallization processes, and by the way in which a magma interacts with its wall rocks. Concentrating on the trace element and isotope contents of basalts to the exclusion of the field relations, petrology, major element data, and phase equilibria is as improvident as slaughtering the buffalo for the sake of its tongue. The crust is a cool boundary layer and a density filter, which impedes the upward transfer of hot, dense "primary" picritic and komatiitic liquids. Planetary crusts are sites of large-scale contamination and extensive partial crystallization of primitive melts striving to escape to the surface. Escape of truly unmodified primitive melts to the surface is a rare event, requiring the resolution of daunting problems in chemical and mechanical engineering. Primary status for volumetrically abundant basalts such as mid-ocean ridge basalt, ocean island basalt, and continental flood basalts is denied by their low-pressure cotectic character, first remarked upon on petrological grounds in 1928 and on experimental grounds in 1962. These basalt liquids are products of crystal-liquid separation at low pressure. Primary status for these common basalts is further denied by the phase equilibria of such compositions at elevated pressures, when the required residual mantle mineralogy (magnesian olivine and orthopyroxene) is not stable at the liquidus. It is also denied by the picritic or komatiitic nature of partial melts of candidate upper-mantle compositions at high pressures - a conclusion supported by calculation of the melt composition, which would need to be extracted in order to explain the chemical variation between fertile and residual peridotite in natural ultramafic rock suites. The subtleties of magma chamber partial crystallization processes can produce an astounding array of "pseudospidergrams," a small selection of which have been explored here. Major modification of the trace element geochemistry and trace element ratios, even those of the highly incompatible elements, must always be entertained whenever the evidence suggests the possibility of partial crystallization. At one extreme, periodically recharged, periodically tapped magma chambers might undergo partial crystallization by ˜95% consolidation of a succession of small packets of the magma. Refluxing of the 5% residual melts from such a process into the main body of melt would lead to eventual discrimination between highly incompatible elements in that residual liquid comparable with that otherwise achieved by 0.1 to 0.3% liquid extraction in equilibrium partial melting. Great caution needs to be exercised in attempting the reconstruction of more primitive compositions by addition of troctolite, gabbro, and olivine to apparently primitive lava compositions. Special attention is focussed on the phase equilibria involving olivine, plagioclase (i.e., troctolite), and liquid because a high proportion of erupted basalts carry these two phases as phenocrysts, yet the equilibria are restricted to crustal pressures and are only encountered by wide ranges of basaltic compositions at pressures less than 0.5 GPa. The mere presence of plagioclase phenocrysts may be sufficient to disqualify candidate primitive magmas. Determination of the actual contributions of crustal processes to petrogenesis requires a return to detailed field, experimental, and forensic petrologic studies of individual erupted basalt flows; of a multitude of cumulate gabbros and their contacts; and of upper-mantle outcrops.

Characterisation of an ion source on the Helix MC Plus noble gas mass spectrometer - pressure dependent mass discrimination

NASA Astrophysics Data System (ADS)

Zhang, X.

2017-12-01

Characterisation of an ion source on the Helix MC Plusnoble gas mass spectrometer - pressure dependent mass discrimination Xiaodong Zhang* dong.zhang@anu.edu.au Masahiko Honda Masahiko.honda@anu.edu.au Research School of Earth Sciences, The Australian National University, Canberra, Australia To obtain reliable measurements of noble gas elemental and isotopic abundances in a geological sample it is essential that the mass discrimination (instrument-induced isotope fractionation) of the mass spectrometer remain constant over the working range of noble gas partial pressures. It is known, however, that there are pressure-dependent variations in sensitivity and mass discrimination in conventional noble gas mass spectrometers [1, 2, 3]. In this study, we discuss a practical approach to ensuring that the pressure effect in the Helix MC Plus high resolution, multi-collector noble gas mass spectrometer is minimised. The isotopic composition of atmospheric Ar was measured under a range of operating conditions to test the effects of different parameters on Ar mass discrimination. It was found that the optimised ion source conditions for pressure independent mass discrimination for Ar were different from those for maximised Ar sensitivity. The optimisation can be achieved by mainly adjusting the repeller voltage. It is likely that different ion source settings will be required to minimise pressure-dependent mass discrimination for different noble gases. A recommended procedure for tuning an ion source to reduce pressure dependent mass discrimination will be presented. References: Honda M., et al., Geochim. Cosmochim. Acta, 57, 859 -874, 1993. Burnard P. G., and Farley K. A., Geochemistry Geophysics Geosystems, Volume 1, 2000GC00038, 2000. Mabry J., et al., Journal of Analytical Atomic Spectrometry, 27, 1012 - 1017, 2012.

High-pressure NaCl-phase of tetrahedral compounds

NASA Astrophysics Data System (ADS)

Soma, T.; -Matsuo Kagaya, H.

1984-04-01

The phase transition of tetrahedral compounds such as GaP, InP, ZnS, ZnSe, ZnTe and CdTe under pressure is investigated from the electronic theory of solids by using our recently presented binding force, which includes mainly covalent interactions in the pseudopotential formalism and partially ionic interactions. The partially ionic forces give the important contributions to the high-pressure phase and stabilize the NaCl-type structure for the high-pressure phase of these compounds, although not reported for GaP experimentally. Then, the numerical results such as the transition pressure, the volume-discontinuity, the transition heat with respect to the pressure-induced phase transition from the zinc-blende-to the NaCl-type lattice are obtained theoretically.

Percutaneous Dilational Tracheotomy in Solid-Organ Transplant Recipients.

PubMed

Ozdemirkan, Aycan; Ersoy, Zeynep; Zeyneloglu, Pinar; Gedik, Ender; Pirat, Arash; Haberal, Mehmet

2015-11-01

Solid-organ transplant recipients may require percutaneous dilational tracheotomy because of prolonged mechanical ventilation or airway issues, but data regarding its safety and effectiveness in solid-organ transplant recipients are scarce. Here, we evaluated the safety, effectiveness, and benefits in terms of lung mechanics, complications, and patient comfort of percutaneous dilational tracheotomy in solid-organ transplant recipients. Medical records from 31 solid-organ transplant recipients (median age of 41.0 years [interquartile range, 18.0-53.0 y]) who underwent percutaneous dilational tracheotomy at our hospital between January 2010 and March 2015 were analyzed, including primary diagnosis, comorbidities, duration of orotracheal intubation and mechanical ventilation, length of intensive care unit and hospital stays, the time interval between transplant to percutaneous dilational tracheotomy, Acute Physiology and Chronic Health Evaluation II score, tracheotomy-related complications, and pulmonary compliance and ratio of partial pressure of arterial oxygen to fraction of inspired oxygen. The median Acute Physiology and Chronic Health Evaluation II score on admission was 24.0 (interquartile range, 18.0-29.0). The median interval from transplant to percutaneous dilational tracheotomy was 105.5 days (interquartile range, 13.0-2165.0 d). The only major complication noted was left-sided pneumothorax in 1 patient. There were no significant differences in ratio of partial pressure of arterial oxygen to fraction of inspired oxygen before and after procedure (170.0 [interquartile range, 102.2-302.0] vs 210.0 [interquartile range, 178.5-345.5]; P = .052). However, pulmonary compliance results preprocedure and postprocedure were significantly different (0.020 L/cm H2O [interquartile range, 0.015-0.030 L/cm H2O] vs 0.030 L/cm H2O [interquartile range, 0.020-0.041 L/cm H2O); P = .001]). Need for sedation significantly decreased after tracheotomy (from 17 patients [54.8%] to 8 patients [25.8%]; P = .004]). Percutaneous dilational tracheotomy with bronchoscopic guidance is an efficacious and safe technique for maintaining airways in solidorgan transplant recipients who require prolonged mechanical ventilation, resulting in possible improvements in ventilatory mechanics and patient comfort.

Design and Operation of Cryogenic Distillation Research Column for Ultra-Low Background Experiments

NASA Astrophysics Data System (ADS)

Chiller, Christopher; Alanson Chiller, Angela; Jasinski, Benjamin; Snyder, Nathan; Mei, Dongming

2013-04-01

Motivated by isotopically enriched germanium (76Ge and 73Ge) for monocrystalline crystal growth for neutrinoless double-beta decay and dark matter experiments, a cryogenic distillation research column was developed. Without market availability of distillation columns in the temperature range of interest with capabilities necessary for our purposes, we designed, fabricated, tested, refined and operated a two-meter research column for purifying and separating gases in the temperature range from 100-200K. Due to interest in defining stratification, purity and throughput optimization, capillary lines were integrated at four equidistant points along the length of the column such that real-time residual gas analysis could guide the investigation. Interior gas column temperatures were monitored and controlled within 0.1oK accuracy at the top and bottom. Pressures were monitored at the top of the column to four significant figures. Subsequent impurities were measured at partial pressures below 2E-8torr. We report the performance of the column in this paper.

Chemical strain engineering of magnetism in PrVO3 thin films

NASA Astrophysics Data System (ADS)

Prellier, Wilfrid; Copie, Olivier; Varignon, Julien; Rotella, Helene; Steciuk, Gwladys; Boullay, Philippe; Pautrat, Alain; David, Adrian; Mercey, Bernard; Ghosez, Philippe

Transition metal oxides having a perovskite structure present a wide range of functional properties ranging from insulator-to-metal, ferroelectricity, colossal magnetoresistance, high-temperature superconductivity and multiferroicity. Such systems are generally characterized by strong electronic correlations, complex phase diagrams and competing ground states. In addition, small perturbation induced by external stimuli (electric or magnetic field, temperature, strain, pressure..) may change structure, and ultimately modify the physical properties. Here, we synthetize an orthorhombic perovskite praseodymium vanadate (PrVO3), which is grown on strontium titanate substrate. We show that the control of the content of oxygen vacancies, the so-called chemical strain, can indeed result in unexpected properties. We further demonstrate that the Néel temperature can be tuned using the same substrate in agreement with first-principles calculations, and demonstrate that monitoring the concentration of oxygen vacancies through the oxygen partial pressure or the growth temperature can produce a substantial macroscopic tensile strain of a few percents.

Oxygen partial pressure influence on the character of InGaZnO thin films grown by PLD

NASA Astrophysics Data System (ADS)

Lu, Yi; Wang, Li

2012-11-01

The amorphous oxide semiconductors (AOSs) are promising for emerging large-area optoelectronic applications because of capability of large-area, uniform deposition at low temperatures such as room temperature (RT). Indium-gallium-zinc oxide (InGaZnO) thin film is a promising amorphous semiconductors material in thin film transistors (TFT) for its excellent electrical properties. In our work, the InGaZnO thin films are fabricated on the SiO2 glass using pulsed laser deposition (PLD) in the oxygen partial pressure altered from 1 to 10 Pa at RT. The targets were prepared by mixing Ga2O3, In2O3, and ZnO powder at a mol ratio of 1: 7: 2 before the solid-state reactions in a tube furnace at the atmospheric pressure. The targets were irradiated by an Nd:YAG laser(355nm). Finally, we have three films of 270nm, 230nm, 190nm thick for 1Pa, 5Pa, 10Pa oxygen partial pressure. The product thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), Hall-effect investigation. The comparative study demonstrated the character changes of the structure and electronic transport properties, which is probably occurred as a fact of the different oxygen partial pressure used in the PLD.

O 1s core levels in Bi2Sr2CaCu2O8+δ single crystals

NASA Astrophysics Data System (ADS)

Parmigiani, F.; Shen, Z. X.; Mitzi, D. B.; Lindau, I.; Spicer, W. E.; Kapitulnik, A.

1991-02-01

High-quality Bi2Sr2CaCu2O8+δ superconducting single crystals, annealed at different oxygen partial pressures, have been studied using angular-resolved x-ray photoelectron spectroscopy with a resolution higher than that used in any previous study. Two states of the oxygen, separated by ~=0.7 eV, are unambiguously observed. Examining these components at different angles makes it possible to distinguish bulk from surface components. Using this capability we discover that annealing under lower oxygen partial pressure (1 atm) results in oxygen intercalation beneath the Bi-O surface layer of the crystal, whereas for higher-pressure anneals (12 atm) additional oxygen is found on the Bi-O surfaces. This steplike intercalation mechanism is also confirmed by the changes observed in the Cu and Bi core lines as a function of the annealing oxygen partial pressure.

Theoretical study of the partial molar volume change associated with the pressure-induced structural transition of ubiquitin

PubMed Central

Imai, Takashi; Ohyama, Shusaku; Kovalenko, Andriy; Hirata, Fumio

2007-01-01

The partial molar volume (PMV) change associated with the pressure-induced structural transition of ubiquitin is analyzed by the three-dimensional reference interaction site model (3D-RISM) theory of molecular solvation. The theory predicts that the PMV decreases upon the structural transition, which is consistent with the experimental observation. The volume decomposition analysis demonstrates that the PMV reduction is primarily caused by the decrease in the volume of structural voids in the protein, which is partially canceled by the volume expansion due to the hydration effects. It is found from further analysis that the PMV reduction is ascribed substantially to the penetration of water molecules into a specific part of the protein. Based on the thermodynamic relation, this result implies that the water penetration causes the pressure-induced structural transition. It supports the water penetration model of pressure denaturation of proteins proposed earlier. PMID:17660257

Theoretical study of the partial molar volume change associated with the pressure-induced structural transition of ubiquitin.

PubMed

Imai, Takashi; Ohyama, Shusaku; Kovalenko, Andriy; Hirata, Fumio

2007-09-01

The partial molar volume (PMV) change associated with the pressure-induced structural transition of ubiquitin is analyzed by the three-dimensional reference interaction site model (3D-RISM) theory of molecular solvation. The theory predicts that the PMV decreases upon the structural transition, which is consistent with the experimental observation. The volume decomposition analysis demonstrates that the PMV reduction is primarily caused by the decrease in the volume of structural voids in the protein, which is partially canceled by the volume expansion due to the hydration effects. It is found from further analysis that the PMV reduction is ascribed substantially to the penetration of water molecules into a specific part of the protein. Based on the thermodynamic relation, this result implies that the water penetration causes the pressure-induced structural transition. It supports the water penetration model of pressure denaturation of proteins proposed earlier.

Petrogenesis of high-Ti and low-Ti basalts: high-pressure and high-temperature experimental study

NASA Astrophysics Data System (ADS)

Yang, J.; WANG, C.; Jin, Z.

2017-12-01

Geochemical and petrological studies have revealed the existence of high-Ti and low-Ti basalts in large igneous provinces. However, the petrogenesis of them are still under debate. Several different mechanisms have been proposed: (1) the high-Ti basalts are formed by the melting of mantle plume containing recycled oceanic crust or delaminated lower crust (Spandler et al., 2008) while low-Ti basalts are formed by the melting of subcontinental lithospheric mantle (Xiao et al., 2004); (2) both of them are from mantle plume or asthenospheric source, but the production of high-Ti basalts are associated with the thick lithosphere and relevant low degrees of melting while the low-Ti basalts are controlled by the thin lithosphere with high degrees of melting (Arndt et al., 1993; Xu et al., 2001). Almost all authors emphasize the role of partial melting but less discuss the crystallization differentiation process. The low Mg# (< 0.7) of these basalts provides that they are far away from direct melting of mantle peridotite. In addition, seismic data indicate unusually high seismic velocities bodies beneath LIPs which explained by the fractionated cumulates from picritic magmas (Farnetani et al., 1996). Therefore, we believed that the crystallization differentiation process might play a more significant role in the genesis of high-Ti and low-Ti basalts. In order to investigate the generation of these basalts, a series of high pressure and high temperature partial crystallization experiments were performed by using piston-cylinder and multi-anvil press at pressures of 1.5, 3.0 and 5.0 GPa and a temperature range of 1200-1700°. Two synthetic picrite glass with different chemical compositions were used as starting materials. Our experimental results show that Ti is preferred to be concentrated in the residual melt during crystallization differentiation. For the same melt fraction, the residual melt of higher pressure experiments has relatively higher TiO2 concentration and higher Mg#. Thus, we propose that most of the high-Ti and low-Ti basalts are inherited from picritic parental magmas which could be formed by high degree partial melting of garnet peridotite. The high-Ti basalts are generated through relatively high pressure crystallization process while the low-Ti basalts are generated at relatively low pressure.

Treatment of ischial pressure sores using a modified gracilis myofasciocutaneous flap.

PubMed

Lin, Haodong; Hou, Chunlin; Chen, Aimin; Xu, Zhen

2010-04-01

Despite the availability of a variety of flap reconstruction options, ischial pressure sores continue to be the most difficult pressure sores to treat. This article describes a successful surgical procedure for the coverage of ischial ulcers using a modified gracilis myofasciocutaneous flap. From August 2000 to April 2004, 12 patients with ischial sores were enrolled in the study. All patients underwent early aggressive surgical debridement followed by surgical reconstruction with a modified gracilis myofasciocutaneous flap. The follow-up period ranged from 13 to 86 months, with a mean of 44 months. Overall, 91.7% of the flaps (11 of 12) survived primarily. Partial flap necrosis occurred in one patient. Primary wound healing occurred without complications at both the donor and recipient sites in all cases. In one patient, grade II ischial pressure sores recurred 13 months after the operation. There was no recurrence in other 11 patients. A modified gracilis myofasciocutaneous flap provides a good cover for ischial pressure sores. Because it is easy to use and has favorable results, it can be used in the primary treatment for large and deep ischial pressure sores. Copyright Thieme Medical Publishers.

Spatial Distribution of Oxygen Chemical Potential under Potential Gradients and Theoretical Maximum Power Density with 8YSZ Electrolyte

NASA Astrophysics Data System (ADS)

Lim, Dae-Kwang; Im, Ha-Ni; Song, Sun-Ju

2016-01-01

The maximum power density of SOFC with 8YSZ electrolyte as the function of thickness was calculated by integrating partial conductivities of charge carriers under various DC bias conditions at a fixed oxygen chemical potential gradient at both sides of the electrolyte. The partial conductivities were successfully taken using the Hebb-Wagner polarization method as a function of temperature and oxygen partial pressure, and the spatial distribution of oxygen partial pressure across the electrolyte was calculated based on Choudhury and Patterson’s model by considering zero electrode polarization. At positive voltage conditions corresponding to SOFC and SOEC, the high conductivity region was expanded, but at negative cell voltage condition, the low conductivity region near n-type to p-type transition was expanded. In addition, the maximum power density calculated from the current-voltage characteristic showed approximately 5.76 W/cm2 at 700 oC with 10 μm thick-8YSZ, while the oxygen partial pressure of the cathode and anode sides maintained ≈0.21 and 10-22 atm.

The Role of the Pressure in the Partial Regularity Theory for Weak Solutions of the Navier-Stokes Equations

NASA Astrophysics Data System (ADS)

Chamorro, Diego; Lemarié-Rieusset, Pierre-Gilles; Mayoufi, Kawther

2018-04-01

We study the role of the pressure in the partial regularity theory for weak solutions of the Navier-Stokes equations. By introducing the notion of dissipative solutions, due to D uchon and R obert (Nonlinearity 13:249-255, 2000), we will provide a generalization of the Caffarelli, Kohn and Nirenberg theory. Our approach sheels new light on the role of the pressure in this theory in connection to Serrin's local regularity criterion.

Solubility of carbon monoxide in n-hexane between 293 and 473 K and CO pressures up to 200 bar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koelliker, R.; Thies, H.

The solubility of carbon monoxide, CO, in n-hexane was measured at 293, 323, 373, 423, and 473 K for CO partial pressures up to 200 bar. The enthalpy of solution was calculated between 293 and 473 K. Using the Krichevsky-Ilinskaya equation of state, the solubility of CO in n-hexane can be calculated between 293 and 423 K for CO partial pressures up to 200 bar with an accuracy better than 5%.

Validation of the i-STAT system for the analysis of blood parameters in fish

PubMed Central

Harter, T. S.; Shartau, R. B.; Brauner, C. J.; Farrell, A. P.

2014-01-01

Portable clinical analysers, such as the i-STAT system, are increasingly being used for blood analysis in animal ecology and physiology because of their portability and easy operation. Although originally conceived for clinical application and to replace robust but lengthy techniques, researchers have extended the use of the i-STAT system outside of humans and even to poikilothermic fish, with only limited validation. The present study analysed a range of blood parameters [pH, haematocrit (Hct), haemoglobin (Hb), HCO3−, partial pressure of CO2 (PCO2), partial pressure of O2 (PO2), Hb saturation (sO2) and Na+ concentration] in a model teleost fish (rainbow trout, Oncorhynchus mykiss) using the i-STAT system (CG8+ cartridges) and established laboratory techniques. This methodological comparison was performed at two temperatures (10 and 20°C), two haematocrits (low and high) and three PCO2 levels (0.5, 1.0 and 1.5%). Our results indicate that pH was measured accurately with the i-STAT system over a physiological pH range and using the i-STAT temperature correction. Haematocrit was consistently underestimated by the i-STAT, while the measurements of Na+, PCO2, HCO3− and PO2 were variably inaccurate over the range of values typically found in fish. The algorithm that the i-STAT uses to calculate sO2 did not yield meaningful results on rainbow trout blood. Application of conversion factors to correct i-STAT measurements is not recommended, due to significant effects of temperature, Hct and PCO2 on the measurement errors and complex interactions may exist. In conclusion, the i-STAT system can easily generate fast results from rainbow trout whole blood, but many are inaccurate values. PMID:27293658

Quantitation of dissolved gas content in emulsions and in blood using mass spectrometric detection.

PubMed

Grimley, Everett; Turner, Nicole; Newell, Clayton; Simpkins, Cuthbert; Rodriguez, Juan

2011-06-01

Quantitation of dissolved gases in blood or in other biological media is essential for understanding the dynamics of metabolic processes. Current detection techniques, while enabling rapid and convenient assessment of dissolved gases, provide only direct information on the partial pressure of gases dissolved in the aqueous fraction of the fluid. The more relevant quantity known as gas content, which refers to the total amount of the gas in all fractions of the sample, can be inferred from those partial pressures, but only indirectly through mathematical modeling. Here we describe a simple mass spectrometric technique for rapid and direct quantitation of gas content for a wide range of gases. The technique is based on a mass spectrometer detector that continuously monitors gases that are rapidly extracted from samples injected into a purge vessel. The accuracy and sample processing speed of the system is demonstrated with experiments that reproduce within minutes literature values for the solubility of various gases in water. The capability of the technique is further demonstrated through accurate determination of O(2) content in a lipid emulsion and in whole blood, using as little as 20 μL of sample. The approach to gas content quantitation described here should greatly expand the range of animals and conditions that may be used in studies of metabolic gas exchange, and facilitate the development of artificial oxygen carriers and resuscitation fluids. Copyright © 2011 Elsevier B.V. All rights reserved.

Case 254: Posttraumatic Migrating Fat Embolus Causing Fat Emboli Syndrome.

PubMed

Molière, Sébastien; Kremer, Stéphane; Bierry, Guillaume

2018-06-01

History An otherwise healthy 18-year-old man was admitted to the emergency department with a closed displaced fracture of the left femoral shaft ( Fig 1 ) after a high-velocity motorbike accident. At admission, other physical examination findings were unremarkable. Initial unenhanced and contrast material-enhanced (120 mL of Iomeron 400; Bracco Imaging, Milan, Italy) computed tomography (CT) was performed in the arterial and venous phases from the head to the knees. No abnormalities were noted in the brain or chest at initial CT. [Figure: see text] Within a few hours, the patient developed sudden mental confusion and severe hypoxemia, with rapidly worsening tachypnea and perturbed arterial blood gas with low partial pressure of oxygen (61 mmHg [8.1 kPa]; normal range, 75-100 mmHg [10.0-13.3 kPa]) and low partial pressure of carbon dioxide (32 mmHg [4.3 kPa]; normal range, 38-42 mmHg [5.1-5.6 kPa]). A second contrast-enhanced chest CT examination and initial brain magnetic resonance (MR) imaging were performed. Femoral fracture was stabilized with external fixation, and the patient was admitted to the intensive care unit, with progressive neurologic recovery at day 3 and respiratory improvement at day 4. Treatment included intubation with mechanical ventilation and intravenous administration of steroids and noradrenaline. Afterward, the femoral fracture was stabilized with an intramedullary nail. The patient made a full neurologic recovery 1 month after the accident.

[Device to assess in-socket pressure distribution for partial foot amputation].

PubMed

Alvarez-Camacho, Michelín; Urrusti, José Luis; Acero, María Del Carmen; Galván Duque-Gastélum, Carlos; Rodríguez-Reyes, Gerardo; Mendoza-Cruz, Felipe

2014-07-01

A device for dynamic acquisition and distribution analysis of in-socket pressure for patients with partial foot amputation is presented in this work. By using the developed system, we measured and generated pressure distribution graphs, obtained maximal pressure, and calculated pressure-time integral (PTI) of three subjects with partial foot amputation and of a group of Healthy subjects (Hs) (n = 10). Average maximal pressure in the healthy group was 19.4 ± 4.11 PSI, while for the three amputated patients, this was 27.8 ± 1.38, 17.6 ± 1.15, 29.10 ± 3.9 PSI, respectively. Maximal pressure-time integral for healthy subjects was 11.56 ± 2.83 PSI*s, and for study subjects was 19.54 ± 1.9, 12.35 ± 1.48, and 13.17 ± 1.31 PSI*s, respectively. The results of the control group agree with those previously reported in the literature. The pressure distribution pattern showed clear differences between study subjects and those of the control group; these graphs allowed us to identify the pressure in regions-of-interest that could be critical, such as surgical scars. The system presented in this work will aid to assess the effectiveness with which prosthetic systems distribute load, given that the formation of ulcers is highly linked to the pressure exercised at the point of contact; in addition, these results will help to investigate the comfort perception of the prosthesis, a factor directly influenced by the stump's pressure distribution.

A Pressure-Based Analysis of Vortex Ring Pinch-Off

NASA Astrophysics Data System (ADS)

Schlueter, Kristy; Braun, Noah; Dabiri, John

2014-11-01

This study investigated the development of vortex rings over a range of maximum stroke ratios, and analyzed vorticity and pressure data for clues to the physical mechanisms underlying vortex pinch-off. An impulsive piston velocity profile and Reynolds number of 3000 were used for all cases. The formation number was consistently found to be 3.6 +/-0.3. A recently developed algorithm was used to generate pressure fields by integrating the pressure gradient along several paths through the velocity field and taking the median to get explicit values for pressure. The formation time at the occurrence of a local maximum in the pressure between the vortex ring and the lip of the nozzle, known as the trailing pressure maximum, was found to occur concurrently with the formation number for each case, within the error associated with the temporal resolution of the data. This suggests that the trailing pressure maximum is an indicator of vortex ring pinch-off. This is consistent with the results of Lawson and Dawson (2014), who found that the appearance of the trailing pressure maximum was coincident with the formation number. This pressure based approach to determining vortex ring pinch-off will be applied to a biological flow to examine the efficiency of such a flow. This research was partially supported by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.

Evaluation of thiosulfate as a substitute for hydrogen sulfide in sour corrosion fatigue studies

NASA Astrophysics Data System (ADS)

Kappes, Mariano Alberto

This work evaluates the possibility of replacing hydrogen sulfide (H 2S) with thiosulfate anion (S2O32- ) in sour corrosion fatigue studies. H2S increases the corrosion fatigue crack growth rate (FCGR) and can be present in carbon steel risers and flowlines used in off-shore oil production. Corrosion tests with gaseous H2S require special facilities with safety features, because H2S is a toxic and flammable gas. The possibility of replacing H2S with S2O32-, a non-toxic anion, for studying stress corrosion cracking of stainless and carbon steels in H2S solutions was first proposed by Tsujikawa et al. ( Tsujikawa et al., Corrosion, 1993. 49(5): p. 409-419). In this dissertation, Tsujikawa work will be extended to sour corrosion fatigue of carbon steels. H2S testing is often conducted in deareated condition to avoid oxygen reaction with sulfide that yields sulfur and to mimic oil production conditions. Nitrogen deareation was also adopted in S2O3 2- testing, and gas exiting the cell was forced through a sodium hydroxide trap. Measurements of the sulfide content of this trap were used to estimate the partial pressure of H2S in nitrogen, and Henry's law was used to estimate the content of H2S in the solution in the cell. H2S was produced by a redox reaction of S2O 32-, which required electrons from carbon steel corrosion. This reaction is spontaneous at the open circuit potential of steel. Therefore, H2S concentration was expected to be maximum at the steel surface, and this concentration was estimated by a mass balance analysis. Carbon steel specimens exposed to S2O32- containing solutions developed a film on their surface, composed by iron sulfide and cementite. The film was not passivating and a good conductor of electrons. Hydrogen permeation experiments proved that this film controls the rate of hydrogen absorption of steels exposed to thiosulfate containing solutions. The absorption of hydrogen in S2O3 2- solutions was compared with the absorption of hydrogen in solutions saturated with different H2S partial pressures. The partial pressure was selected so that the concentration of H2S in the solution saturated with the gas would be the same as that reached in the surface of steel freely corroding in the thiosulfate solution. For solutions obtained by bubbling H2S, the rate of hydrogen absorption increased with the partial pressure of the gas, but the rate of hydrogen absorption reached a maximum at 10-3 M S2O3 2-, despite the surface concentration of H2S increased with the concentration of S2O32-. This effect was associated with the formation of thicker films, which inhibited the absorption of hydrogen. FCGR were evaluated at constant stress intensity factor range. Crack length was monitored in-situ by the direct current potential drop (DCPD) method. FCGR increased with the partial pressure of H2S in nitrogen. FCGR was controlled not only by the amount of hydrogen present in the steel, but also by inhibiting contributions like crack closure and crack tip blunting. FCGR in dilute thiosulfate solutions was near that measured in a solution saturated with a partial pressure of H2S equal to 0.56 kPa, in accord with hydrogen permeation results.

Analytical and Experimental Studies of Leak Location and Environment Characterization for the International Space Station

NASA Technical Reports Server (NTRS)

Woronowicz, Michael; Abel, Joshua; Autrey, David; Blackmon, Rebecca; Bond, Tim; Brown, Martin; Buffington, Jesse; Cheng, Edward; DeLatte, Danielle; Garcia, Kelvin;

Analytical and Experimental Studies of Leak Location and Environment Characterization for the International Space Station

NASA Technical Reports Server (NTRS)

Woronowicz, Michael S.; Abel, Joshua C.; Autrey, David; Blackmon, Rebecca; Bond, Tim; Brown, Martin; Buffington, Jesse; Cheng, Edward; DeLatte, Danielle; Garcia, Kelvin;

Microwave plasma torches used for hydrogen production

NASA Astrophysics Data System (ADS)

Dias, F. M.; Bundaleska, N.; Henriques, J.; Tatarova, E.; Ferreira, C. M.

2014-06-01

A microwave plasma torch operating at 2.45 GHz and atmospheric pressure has been used as a medium and a tool for decomposition of alcohol in order to produce molecular hydrogen. Plasma in a gas mixture of argon and ethanol/methanol, with or without water, has been created using a waveguide surfatron launcher and a microwave generator delivering a power in the range 0.2-2.0 kW. Mass, Fourier Transform Infrared, and optical emission spectrometry have been applied as diagnostic tools. The decomposition yield of methanol was nearly 100 % with H2, CO, CO2, H2O, and solid carbon as the main reaction products. The influence of the fraction of Ar flow through the liquid ethanol/methanol on H2, CO, and CO2 partial pressures has been investigated, as well as the dependence of the produced H2 flow on the total flow and power. The optical emission spectrum in the range 250-700 nm has also been detected. There is a decrease of the OH(A-X) band intensity with the increase of methanol in the mixture. The emission of carbon atoms in the near UV range (240-300 nm) exhibits a significant increase as the amount of alcohol in the mixture grows. The obtained results clearly show that this microwave plasma torch at atmospheric pressure provides an efficient plasma environment for hydrogen production.

Aerodynamic forces and flows of the full and partial clap-fling motions in insects

PubMed Central

Sun, Mao

2017-01-01

Most of the previous studies on Weis-Fogh clap-fling mechanism have focused on the vortex structures and velocity fields. Detailed pressure distribution results are provided for the first time in this study to reveal the differences between the full and the partial clap-fling motions. The two motions are studied by numerically solving the Navier–Stokes equations in moving overset grids. The Reynolds number is set to 20, relevant to the tiny flying insects. The following has been shown: (1) During the clap phase, the wings clap together and create a high pressure region in the closing gap between wings, greatly increasing the positive pressure on the lower surface of wing, while pressure on the upper surface is almost unchanged by the interaction; during the fling phase, the wings fling apart and create a low pressure region in the opening gap between wings, greatly increasing the suction pressure on the upper surface of wing, while pressure on the lower surface is almost unchanged by the interaction; (2) The interference effect between wings is most severe at the end of clap phase and the start of the fling phase: two sharp force peaks (8–9 times larger than that of the one-winged case) are generated. But the total force peaks are manifested mostly as drag and barely as lift of the wing, owing to the vertical orientation of the wing section; (3) The wing–wing interaction effect in the partial clap-fling case is much weaker than that in the full clap-fling case, avoiding the generation of huge drag. Compared with a single wing flapping with the same motion, mean lift in the partial case is enhanced by 12% without suffering any efficiency degradation, indicating that partial clap-fling is a more practical choice for tiny insects to employ. PMID:28289562

A simulation model of the oxygen alveolo-capillary exchange in normal and pathological conditions.

PubMed

Brighenti, Chiara; Gnudi, Gianni; Avanzolini, Guido

2003-05-01

This paper presents a mathematical model of the oxygen alveolo-capillary exchange to provide the capillary oxygen partial pressure profile in normal and pathological conditions. In fact, a thickening of the blood-gas barrier, heavy exercise or a low oxygen partial pressure (PO2) in the alveolar space can reduce the O2 alveolo-capillary exchange. Since the reversible binding between haemoglobin and oxygen makes it impossible to determine the closed form for the mathematical description of the PO2 profile along the pulmonary capillaries, an approximate analytical solution of the capillary PO2 profile is proposed. Simulation results are compared with the capillary PO2 profile obtained by numerical integration and by a piecewise linear interpolation of the oxyhaemoglobin dissociation curve. Finally, the proposed model is evaluated in a large range of physiopathological diffusive conditions. The good fit to numerical solutions in all experimental conditions seems to represent a substantial improvement with respect to the approach based on a linear approximation of the oxyhaemoglobin dissociation curve, and makes this model a candidate to be incorporated into the integrated descriptions of the entire respiratory system, where the datum of primary interest is the value of end capillary PO2.

Phase Equilibria of ``Cu2O''-``FeO''-CaO-MgO-Al2O3 Slags at PO2 of 10-8.5 atm in Equilibrium with Metallic Copper for a Copper Slag Cleaning Production

NASA Astrophysics Data System (ADS)

Henao, Hector M.; Pizarro, Claudio; Font, Jonkion; Moyano, Alex; Hayes, Peter C.; Jak, Evgueni

2010-12-01

Limited data are available on phase equilibria of the multicomponent slag system at the oxygen partial pressures used in the copper smelting, converting, and slag-cleaning processes. Recently, experimental procedures have been developed and have been applied successfully to characterize several complex industrial slags. The experimental procedures involve high-temperature equilibration on a substrate and quenching followed by electron probe X-ray microanalysis. This technique has been used to construct the liquidus for the “Cu2O”-“FeO”-SiO2-based slags with 2 wt pct of CaO, 0.5 wt pct of MgO, and 4.0 wt pct of Al2O3 at controlled oxygen partial pressures in equilibrium with metallic copper. The selected ranges of compositions and temperatures are directly relevant to the copper slag-cleaning processes. The new experimental equilibrium results are presented in the form of ternary sections and as a liquidus temperature vs Fe/SiO2 weight ratio diagram. The experimental results are compared with the FactSage thermodynamic model calculations.

The study of excited oxygen molecule gas species production and quenching on thermal protection system materials

NASA Technical Reports Server (NTRS)

Nordine, Paul C.; Fujimoto, Gordon T.; Greene, Frank T.

1987-01-01

The detection of excited oxygen and ozone molecules formed by surface catalyzed oxygen atom recombination and reaction was investigated by laser induced fluorescence (LIF), molecular beam mass spectrometric (MBMS), and field ionization (FI) techniques. The experiment used partially dissociated oxygen flows from a microwave discharge at pressures in the range from 60 to 400 Pa or from an inductively coupled RF discharge at atmospheric pressure. The catalyst materials investigated were nickel and the reaction cured glass coating used for Space Shuttle reusable surface insulation tiles. Nonradiative loss processes for the laser excited states makes LIF detection of O2 difficult such that formation of excited oxygen molecules could not be detected in the flow from the microwave discharge or in the gaseous products of atom loss on nickel. MBMS experiments showed that ozone was a product of heterogeneous O atom loss on nickel and tile surfaces at low temperatures and that ozone is lost on these materials at elevated temperatures. FI was separately investigated as a method by which excited oxygen molecules may be conveniently detected. Partial O2 dissociation decreases the current produced by FI of the gas.

Hydrogen uptake characteristics of mischmetal based alloy

NASA Astrophysics Data System (ADS)

Jain, Ankur; Jain, R. K.; Jain, I. P.

Hydrogen storage properties of Mm 39.2Ni 42.1Mn 4.9Al 1.25Co 10.2Fe 2.35 alloy have been systematically studied in the present work. An attempt is made to relate the content of hydrogen with change in resistance. It is found that the resistance of material increases with the increase in value of H/ M due to hydrogen absorption. Pressure composition (P-C-T) isotherm using water displacement method has been investigated in the temperature and pressure ranges of 308 ≤ T ≤ 338 K and 0.5 ≤ P ≤ 10 bar, respectively. The P-C isotherms show the presence of two single α and β regions one mixed α + β phase. The maximum H (wt%) was found to be around 1.53 at 308 K and around 6 bar. Since enthalpy is an index of thermochemical stability of metal hydride the thermo dynamical parameters viz., the relative partial molar enthalpy (Δ H) and relative partial molar entropy (Δ S) of dissolved hydrogen have been calculated by plotting the Van't Hoff plot. The variation of Δ H and Δ S with the hydrogen concentration confirm the phase boundaries.

Seasonal changes in blood oxygen transport and acid-base status in the tegu lizard, Tupinambis merianae.

PubMed

Andrade, Denis V; Brito, Simone P; Toledo, Luís Felipe; Abe, Augusto S

2004-05-20

Oxygen-binding properties, blood gases, and acid-base parameters were studied in tegu lizards, Tupinambis merianae, at different seasons and temperatures. Independent of temperature and pH, blood oxygen affinity was higher in dormant lizards than in those active during the summer. Haematocrit (Hct) and hemoglobin content ([Hb]) were greater in active lizards resulting in a higher oxygen-carrying capacity. Nucleoside triphosphate content ([NTP]) was reduced during dormancy, but the ratio between [NTP] and [Hb] remained unchanged. Dormancy was accompanied by an increase in plasma bicarbonate ([HCO-(3)]pl) and an elevation of arterial CO2 partial pressure (PaCO2) and CO2 content in the plasma (CplCO2). These changes in acid-base parameters persist over a broad range of body temperatures. In vivo, arterial O2 partial pressure (PaO2) and O2 content (CaO2) were not affected by season and tended to increase with temperature. Arterial pH (pHa) of dormant animals is reduced compared to active lizards at body temperatures below 15 degrees C, while no significant difference was noticed at higher temperatures. Copyright 2003 Elsevier B.V.

Lead zirconate titanate thin films directly on copper electrodes for ferroelectric, dielectric and piezoelectric applications

NASA Astrophysics Data System (ADS)

Kingon, Angus I.; Srinivasan, Sudarsan

2005-03-01

Replacement of noble metal electrodes by base metals significantly lowers the cost of ferroelectric, piezoelectric and dielectric devices. Here, we demonstrate that it is possible to process lead zirconate (Pb(Zr0.52Ti0.48)O3, or PZT) thin films directly on base metal copper foils. We explore the impact of the oxygen partial pressure during processing, and demonstrate that high-quality films and interfaces can be achieved through control of the oxygen partial pressure within a narrow window predicted by thermodynamic stability considerations. This demonstration has broad implications, opening up the possibility of the use of low-cost, high-conductivity copper electrodes for a range of Pb-based perovskite materials, including PZT films in embedded printed circuit board applications for capacitors, varactors and sensors; multilayer PZT piezoelectric stacks; and multilayer dielectric and electrostrictive devices based on lead magnesium niobate-lead titanate. We also point out that the capacitors do not fatigue on repeated switching, unlike those with Pt noble metal electrodes. Instead, they appear to be fatigue-resistant, like capacitors with oxide electrodes. This may have implications for ferroelectric non-volatile memories.

The e[sup [minus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holroyd, R.A.; Schwarz, H.A.; Stradowska, E.

The rate constants for attachment of excess electrons to 1,3-butadiene (k[sub a]) and detachment from the butadiene anion (k[sub d]) in n-hexane are reported. The equilibrium constant, K[sub eq] = k[sub a]/k[sub d], increases rapidly with pressure and decreases as the temperature increases. At -7[degree]C attachment is observed at 1 bar. At high pressures the attachment rate is diffusion controlled. The activation energy for detachment is about 21 kcal/mol; detachment is facilitated by the large entropy of activation. The reaction volumes for attachment range from -181 cm[sup 3]/mol at 400 bar to-122 cm[sup 3]/mol at 1500 bar and are largelymore » attributed to the electrostriction volume of the butadiene anion ([Delta][bar V][sub el]). Values of [Delta][bar V][sub el] calculated by a model, which includes a glassy shell of solvent molecules around the ion, are in agreement with experimental reaction volumes. The analysis indicates the partial molar volume of the electron in hexane is small and probably negative. It is shown that the entropies of reaction are closely related to the partial molar volumes of reaction. 22 refs., 5 figs., 5 tabs.« less

Chlorine-containing salts as water ice nucleating particles on Mars

NASA Astrophysics Data System (ADS)

Santiago-Materese, D. L.; Iraci, L. T.; Clapham, M. E.; Chuang, P. Y.

2018-03-01

Water ice cloud formation on Mars largely is expected to occur on the most efficient ice nucleating particle available. Salts have been observed on the Martian surface and have been known to facilitate water cloud formation on Earth. We examined heterogeneous ice nucleation onto sodium chloride and sodium perchlorate substrates under Martian atmospheric conditions, in the range of 150 to 180 K and 10-7 to 10-5 Torr water partial pressure. Sub-155 K data for the critical saturation ratio (Scrit) suggests an exponential model best describes the temperature-dependence of nucleation onset of water ice for all substrates tested. While sodium chloride does not facilitate water ice nucleation more easily than bare silicon, sodium perchlorate does support depositional nucleation at lower saturation levels than other substrates shown and is comparable to smectite-rich clay in its ability to support cloud initiation. Perchlorates could nucleate water ice at partial pressures up to 40% lower than other substrates examined to date under Martian atmospheric conditions. These findings suggest air masses on Mars containing uplifted salts such as perchlorates could form water ice clouds at lower saturation ratios than in air masses absent similar particles.

Roles of air stored in burrows of the mudskipper Boleophthalmus pectinirostris for adult respiration and embryonic development.

PubMed

Toba, A; Ishimatsu, A

2014-03-01

Air was stored in 90% of Boleophthalmus pectinirostris burrows in summer breeding months when fish were active on the mudflat surface during low tide but only in 50% of burrows in overwintering months when the fish confined themselves to burrows. The volume of gas recovered from the burrows ranged from 30 to > 400 ml. The partial pressure of oxygen (PO₂) of the gas varied from 5 to 20 kPa and was inversely related to the partial pressure of carbon dioxide (PCO₂) in all but the wintering periods. Sampling in July demonstrated that gas was stored in both male and female burrows with no difference in volume, PO₂ or PCO₂ between them. Adult fish were able to survive total submersion in hypoxic (PO₂ = 1.96 kPa) water for 8 h, but no embryos survived to hatch in the hypoxic aquatic environment. Thus, the deposited air appears to be a crucial source of oxygen for the embryos developing in the egg chamber of the burrow, but may play only a subsidiary role for adult respiration during presumed high-tide confinement. © 2014 The Fisheries Society of the British Isles.

Chromium Distribution between Liquid Slag and Matte Phases

NASA Astrophysics Data System (ADS)

Eric, R. Hurman

The distribution of chromium between liquid silicate slags and copper-iron-nickel matte phases encountered in electric smelting of PGM containing South African sulphide concentrates were experimentally studied under controlled partial pressures of oxygen and sulphur. The reported experiments were conducted under silica saturation through the use of silica crucibles. Seven representative slag compositions were equilibrated with a typical sulphur deficient matte containing 18% Ni, 11% Cu, 42% Fe and 29% S. The slag constituents varied in the following ranges: SiO2: 42-58%, Al2O3: 3.5-9.0%, Fe2O3: 13-21%, MgO: 15.6-25%, CaO: 2-15%, Cr2O3: 0.2-3.5%. The slag and matte samples were synthetically prepared from pure components. The chromium content of the two phases was analysed chemically. According to the present available results of this ongoing research it was found that the partition of chromium to the matte phase decreased with an increase in the partial pressures of both oxygen and sulphur where the value of the distribution coefficient of chromium between the matte and the slag phase varied from as low as 0.07 to as high as 5.5.

Zero-Boil-Off Tank (ZBOT) Experiment: Ground-Based Validation of Self-Pressurization and Pressure Control Two-Phase CFD Model

NASA Technical Reports Server (NTRS)

Kassemi, Mohammad; Hylton, Sonya; Kartuzova, Olga

2017-01-01

Integral to all phases of NASA's projected space and planetary expeditions is affordable and reliable cryogenic fluid storage for use in propellant or life support systems. Cryogen vaporization due to heat leaks into the tank from its surroundings and support structure can cause self-pressurization relieved through venting. This has led to a desire to develop innovative pressure control designs based on mixing of the bulk tank fluid together with some form of active or passive cooling to allow storage of the cryogenic fluid with zero or reduced boil-off. The Zero-Boil-Off Tank (ZBOT) Experiments are a series of small scale tank pressurization and pressure control experiments aboard the International Space Station (ISS) that use a transparent volatile simulant fluid in a transparent sealed tank to delineate various fundamental fluid flow, heat and mass transport, and phase change phenomena that control storage tank pressurization and pressure control in microgravity. The hardware for ZBOT-1 flew to ISS on the OA-7 flight in April 2017 and operations are planned to begin in September 2017, encompassing more than 90 tests. This paper presents preliminary results from ZBOT's ground-based research delineating both pressurization and pressure reduction trends in the sealed test tank. Tank self-pressurization tests are conducted under three modes: VJ heating, strip heating and simultaneous VJ and strip heating in attempt to simulate heat leaks from the environment, the support structure and both. The jet mixing pressure control studies are performed either from an elevated uniform temperature condition or from thermally stratified conditions following a self-pressurization run. Jet flow rates are varied from 2-25 cm/s spanning a range of jet Re number in laminar, transitional, and turbulent regimes and a range of Weber numbers covering no ullage penetration, partial penetration and complete ullage penetration and break-up (only in microgravity). Numerical prediction of a two-phase CFD model are compared to experimental 1g results to both validate the model and also indicate the effect of the residual non-condensable gas on evolution of pressure and temperature distributions in the tank during pressurization and pressure control.

Experimental investigation of insolation-driven dust ejection from Mars' CO2 ice caps

NASA Astrophysics Data System (ADS)

Kaufmann, E.; Hagermann, A.

2017-01-01

Mars' polar caps are - depending on hemisphere and season - partially or totally covered with CO2 ice. Icy surfaces such as the polar caps of Mars behave differently from surfaces covered with rock and soil when they are irradiated by solar light. The latter absorb and reflect incoming solar radiation within a thin layer beneath the surface. In contrast, ices are partially transparent in the visible spectral range and opaque in the infrared. Due to this fact, the solar radiation can penetrate to a certain depth and raise the temperature of the ice or dust below the surface. This may play an important role in the energy balance of icy surfaces in the solar system, as already noted in previous investigations. We investigated the temperature profiles inside CO2 ice samples including a dust layer under Martian conditions. We have been able to trigger dust eruptions, but also demonstrated that these require a very narrow range of temperature and ambient pressure. We discuss possible implications for the understanding of phenomena such as arachneiform patterns or fan shaped deposits as observed in Mars' southern polar region.

Separating the roles of nitrogen and oxygen in high pressure-induced blood-borne microparticle elevations, neutrophil activation, and vascular injury in mice.

PubMed

Yang, Ming; Bhopale, Veena M; Thom, Stephen R

2015-08-01

An elevation in levels of circulating microparticles (MPs) due to high air pressure exposure and the associated inflammatory changes and vascular injury that occur with it may be due to oxidative stress. We hypothesized that these responses arise due to elevated partial pressures of N2 and not because of high-pressure O2. A comparison was made among high-pressure air, normoxic high-pressure N2, and high-pressure O2 in causing an elevation in circulating annexin V-positive MPs, neutrophil activation, and vascular injury by assessing the leakage of high-molecular-weight dextran in a murine model. After mice were exposed for 2 h to 790 kPa air, there were over 3-fold elevations in total circulating MPs as well as subgroups bearing Ly6G, CD41, Ter119, CD31, and CD142 surface proteins-evidence of neutrophil activation; platelet-neutrophil interaction; and vascular injury to brain, omentum, psoas, and skeletal muscles. Similar changes were found in mice exposed to high-pressure N2 using a gas mixture so that O2 partial pressure was the same as that of ambient air, whereas none of these changes occurred after exposures to 166 kPa O2, the same partial pressure that occurs during high-pressure air exposures. We conclude that N2 plays a central role in intra- and perivascular changes associated with exposure to high air pressure and that these responses appear to be a novel form of oxidative stress. Copyright © 2015 the American Physiological Society.

Real-Time Monitoring of Singlet Oxygen and Oxygen Partial Pressure During the Deep Photodynamic Therapy In Vitro.

PubMed

Li, Weitao; Huang, Dong; Zhang, Yan; Liu, Yangyang; Gu, Yueqing; Qian, Zhiyu

2016-09-01

Photodynamic therapy (PDT) is an effective noninvasive method for the tumor treatment. The major challenge in current PDT research is how to quantitatively evaluate therapy effects. To our best knowledge, this is the first time to combine multi-parameter detection methods in PDT. More specifically, we have developed a set of system, including the high-sensitivity measurement of singlet oxygen, oxygen partial pressure and fluorescence image. In this paper, the detection ability of the system was validated by the different concentrations of carbon quantum dots. Moreover, the correlation between singlet oxygen and oxygen partial pressure with laser irradiation was observed. Then, the system could detect the signal up to 0.5 cm tissue depth with 660 nm irradiation and 1 cm tissue depth with 980 nm irradiation by using up-conversion nanoparticles during PDT in vitro. Furthermore, we obtained the relationship among concentration of singlet oxygen, oxygen partial pressure and tumor cell viability under certain conditions. The results indicate that the multi-parameter detection system is a promising asset to evaluate the deep tumor therapy during PDT. Moreover, the system might be potentially used for the further study in biology and molecular imaging.

Positron beam study of indium tin oxide films on GaN

NASA Astrophysics Data System (ADS)

Cheung, C. K.; Wang, R. X.; Beling, C. D.; Djurisic, A. B.; Fung, S.

2007-02-01

Variable energy Doppler broadening spectroscopy has been used to study open-volume defects formed during the fabrication of indium tin oxide (ITO) thin films grown by electron-beam evaporation on n-GaN. The films were prepared at room temperature, 200 and 300 °C without oxygen and at 200 °C under different oxygen partial pressures. The results show that at elevated growth temperatures the ITO has fewer open volume sites and grows with a more crystalline structure. High temperature growth, however, is not sufficient in itself to remove open volume defects at the ITO/GaN interface. Growth under elevated temperature and under partial pressure of oxygen is found to further reduce the vacancy type defects associated with the ITO film, thus improving the quality of the film. Oxygen partial pressures of 6 × 10-3 mbar and above are found to remove open volume defects associated with the ITO/GaN interface. The study suggests that, irrespective of growth temperature and oxygen partial pressure, there is only one type of defect in the ITO responsible for trapping positrons, which we tentatively attribute to the oxygen vacancy.

Near 7-day response of ocean bottom pressure to atmospheric surface pressure and winds in the northern South China Sea

NASA Astrophysics Data System (ADS)

Zhang, Kun; Zhu, Xiao-Hua; Zhao, Ruixiang

2018-02-01

Ocean bottom pressures, observed by five pressure-recording inverted echo sounders (PIESs) from October 2012 to July 2014, exhibit strong near 7-day variability in the northern South China Sea (SCS) where long-term in situ bottom pressure observations are quite sparse. This variability was strongest in October 2013 during the near two years observation period. By joint analysis with European Center for Medium-Range Weather Forecasts (ECMWF) data, it is shown that the near 7-day ocean bottom pressure variability is closely related to the local atmospheric surface pressure and winds. Within a period band near 7 days, there are high coherences, exceeding 95% significance level, of observed ocean bottom pressure with local atmospheric surface pressure and with both zonal and meridional components of the wind. Ekman pumping/suction caused by the meridional component of the wind in particular, is suggested as one driving mechanism. A Kelvin wave response to the near 7-day oscillation would propagate down along the continental slope, observed at the Qui Nhon in the Vietnam. By multiple and partial coherence analyses, we find that local atmospheric surface pressure and Ekman pumping/suction show nearly equal influence on ocean bottom pressure variability at near 7-day periods. A schematic diagram representing an idealized model gives us a possible mechanism to explain the relationship between ocean bottom pressure and local atmospheric forcing at near 7-day periods in the northern SCS.

High pressure solubility of carbon dioxide (CO2) in aqueous solution of piperazine (PZ) activated N-methyldiethanolamine (MDEA) solvent for CO2 capture

NASA Astrophysics Data System (ADS)

Khan, Saleem Nawaz; Hailegiorgis, Sintayehu Mekuria; Man, Zakaria; Shariff, Azmi Mohd

2017-10-01

In this study, the solubility of carbon dioxide (CO2) in the aqueous solution of piperazine (PZ) activated N-methyldiethanolamine (MDEA) was investigated. In the aqueous solution the concentrations of the N-methyldiethanolamine (MDEA) and piperazine (PZ) were kept constant at 30 wt. % and 3 wt. %, respectively. The solubility experiments were carried out between the temperatures ranges of 303.15 to 333.15 K. The pressure range was selected as 2-50 bar for solubility of carbon dioxide in the aqueous solution. The solubility of the CO2 is reported in terms of CO2 loading capacity of the solvent. The loading capacity of the solvent is the ratio between the numbers of moles of CO2 absorbed to the numbers of moles of solvent used. The experimental data showed that the CO2 loading increased with increase in CO2 partial pressure, while it decreased with increase in system's temperature. It was also observed from the experimental data that the higher pressure favors the absorption process while the increased temperature hinders the absorption process of CO2 capture. The loading capacity of the investigated solvent was compared with the loading capacity of the solvents reported in the literature. The investigated solvent showed better solubility in terms of loading capacity.

Improving the sensitivity of a torsion pendulum by using an optical spring method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Qinglan; Yeh Hsienchi; Zhou Zebing

We present a scheme aiming at improving the sensitivity of a torsion pendulum by means of radiation-pressure-induced optical spring. Two partial-reflective mirrors are installed on the opposite sides of a torsion pendulum, and one high-reflective mirror is mounted at the end of the torsion beam so that two identical Fabry-Perot cavities can be formed and aligned in series. Due to the antisymmetric radiation pressures acting on the opposite sides of the torsion beam, a negative restoring coefficient can be generated within a certain dynamic range, such that both the resultant torsional rigidity and the resonant frequency of the torsion pendulummore » are reduced, and the minimum detectable response torque in high-frequency region can be reduced accordingly.« less

Fuel quality combustion analysis

NASA Technical Reports Server (NTRS)

Naegeli, D. W.; Moses, C. A.

1979-01-01

A high pressure research combustor operating over a wide range of burner inlet conditions was used to determine the effects of fuel molecular structure on soot formation. Six test fuels with equal hydrogen content (12.8%) were blended to stress different molecular components and final boiling points. The fuels containing high concentrations (20%) of polycyclic aromatics and partially saturated polycyclic structures such as tetralin, produced more soot than would be expected from a hydrogen content correlation for typical petroleum based fuels. Fuels containing naphthenes such as decalin agreed with the hydrogen content correlation. The contribution of polycyclic aromatics to soot formation was equivalent to a reduction in fuel hydrogen content of about one percent. The fuel sensitivity to soot formation due to the polycyclic aromatic contribution decreased as burner inlet pressure and fuel/air ratio increased.

Structure and microhardness of Al-Si-Cu-Ni alloy after severe plastic deformation and high-temperature annealing

NASA Astrophysics Data System (ADS)

Shvets, Karina; Khalikova, Gulnara; Korznikova, Elena; Trifonov, Vadim

2015-10-01

The effect of severe plastic deformation by high-pressure torsion (HPT) and subsequent annealing on the microstructure and microhardness of squeeze casting Al-22%Si-3%Cu-1.7%Ni alloy was investigated. HPT was performed at room temperature with 5 rotations under the pressure of 4 GPa. Annealing temperature range varied from 300 to 500°C for 5 min. HPT resulted in refinement and partial dissolution of the primary silicon and intermetallic particles in aluminum matrix and structure fragmentation that caused the microhardness increase. Subsequent annealing lead to the decomposition of the supersaturated solid solution that took place simultaneously with recovery and recrystallization of the fragmented structure. Increase of annealing temperature resulted in decrease of microhardness values.

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

NASA Astrophysics Data System (ADS)

Hofmann, A. F.; Peltzer, E. T.; Brewer, P. G.

2012-10-01

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

Measurement of Local Partial Pressure of Oxygen in the Brain Tissue under Normoxia and Epilepsy with Phosphorescence Lifetime Microscopy.

PubMed

Zhang, Cong; Bélanger, Samuel; Pouliot, Philippe; Lesage, Frédéric

2015-01-01

In this work a method for measuring brain oxygen partial pressure with confocal phosphorescence lifetime microscopy system is reported. When used in conjunction with a dendritic phosphorescent probe, Oxyphor G4, this system enabled minimally invasive measurements of oxygen partial pressure (pO2) in cerebral tissue with high spatial and temporal resolution during 4-AP induced epileptic seizures. Investigating epileptic events, we characterized the spatio-temporal distribution of the "initial dip" in pO2 near the probe injection site and along nearby arterioles. Our results reveal a correlation between the percent change in the pO2 signal during the "initial dip" and the duration of seizure-like activity, which can help localize the epileptic focus and predict the length of seizure.

Pressure induced swelling in microporous materials

DOEpatents

Vogt, Thomas; Hriljac, Joseph A.; Lee, Yongjae

2006-07-11

A method for capturing specified materials which includes contacting a microporous material with a hydrostatic fluid having at least one specified material carried therein, under pressure which structurally distorts the lattice sufficiently to permit entry of the at least one specified material. The microporous material is capable of undergoing a temporary structural distortion which alters resting lattice dimensions under increased ambient pressure and at least partially returning to rest lattice dimensions when returned to ambient pressure. The pressure of the fluid is then reduced to permit return to at least partial resting lattice dimension while the at least one specified material is therein. By this method, at least one specified material is captured in the microporous material to form a modified microporous material.

CO2 Solubility in Natural Rhyolitic Melts at High Pressures - Implications for Carbon Flux in Subduction Zones by Sediment Partial Melts

NASA Astrophysics Data System (ADS)

Duncan, M. S.; Dasgupta, R.

2011-12-01

Partial melts of subducting sediments is thought to be a critical agent in carrying trace elements and water to arc basalt source regions. For subduction zones that contain significant amount of carbonates in ocean-floor sediments, sediment melts likely also act as a carrier of CO2. However, the CO2 carrying capacity of natural rhyolitic melts at sub-arc depths remains unconstrained. We conducted experiments on a synthetic composition, similar to average, low-degree experimental partial melt of pelitic sediments. The composition was constructed with reagent grade oxides and carbonates, the source of excess CO2. Experiments were conducted between 1 and 3 GPa at 1200 °C in Au80Pd20 capsules using a piston cylinder apparatus with a half-inch BaCO3 assembly at Rice University. Quench products showed glasses with bubbles, the latter suggesting saturation of the melt with a CO2-rich vapor phase. Oxygen fugacity during the experiments was not strictly controlled but the presence of CO2 bubbles and absence of graphite indicates fO2 above the CCO buffer. Major element concentrations of glasses were measured using EPMA. The CO2 and H2O contents of experimental doubly polished (50-110 μm), bubble-free portions of the glass chips were determined using a Thermo Nicolet Fourier Transform Infrared Spectrometer. Spectra were recorded with a resolution of 4 cm-1, 512 scans, from 650 to 4000 cm-1, under a nitrogen purge to eliminate atmospheric gases. Dissolved volatile concentrations were quantified using the Beer-Lambert law and linear molar absorption coefficients from previous studies [1, 2]. Total dissolved carbon dioxide of experimental glasses was determined from the intensity of the ν3 antisymmetric stretch bands of CO32- at 1430 cm-1 and CO2mol at 2348 cm-1. Dissolved water content of experimental glasses was determined from the intensity of O-H stretching at 3520 cm-1. Estimated total CO2 concentrations at 3 GPa are in the range of 1-2 wt%, for melts with H2O contents between 1.5 and 2.5 wt%. Compared to previous work on CO2 solubility in complex rhyolitic melts at lower pressures [3-5], there is a general trend of increasing CO2 solubility with pressure. Dissolved CO2 is present both as molecular CO2 and as CO32-, consistent with previous, simple system studies at high pressures [e.g. 2, 6]. The CO2mol/CO2Tot values are within the range of previous high pressure studies [e.g. 7] and range from 0.35 to 0.55. Experiments at variable P, T, and melt water content are underway. [1] Fine and Stolper (1985), CMP, 91, 105-121; [2] Stolper et al. (1987), AM, 72, 1071-1085; [3] Blank et al. (1993), EPSL, 119, 27-36; [4] Fogel and Rutherford (1990), AM, 75, 1331-1326; [5] Tamic et al. (2001), CG, 174, 333-347; [6] Mysen and Virgo (1980), AM, 65, 855-899; [7] Mysen (1976), AJS, 276, 969-996.

Melting Efficiency During Plasma Arc Welding

NASA Technical Reports Server (NTRS)

McClure, J.C.; Evans, D. M.; Tang, W.; Nunes, A. C.

1999-01-01

A series of partial penetration Variable Polarity Plasma Arc welds were made at equal power but various combinations of current and voltage on 2219 aluminum. Arc Efficiency was measured calorimetrically and ranged between 48% and 66%. Melting efficiency depends on the weld pool shape. Increased current increases the melting efficiency as it increases the depth to width ratio of the weld pool. Higher currents are thought to raise arc pressure and depress the liquid at the bottom of the weld pool causing a more nearly two dimensional heat flow condition.

Clinical recommendations for high altitude exposure of individuals with pre-existing cardiovascular conditions

PubMed Central

Parati, Gianfranco; Agostoni, Piergiuseppe; Basnyat, Buddha; Bilo, Grzegorz; Brugger, Hermann; Coca, Antonio; Festi, Luigi; Giardini, Guido; Lironcurti, Alessandra; Luks, Andrew M; Maggiorini, Marco; Modesti, Pietro A; Swenson, Erik R; Williams, Bryan; Bärtsch, Peter; Torlasco, Camilla

2018-01-01

Abstract Take home figureAdapted from Bärtsch and Gibbs2 Physiological response to hypoxia. Life-sustaining oxygen delivery, in spite of a reduction in the partial pressure of inhaled oxygen between 25% and 60% (respectively at 2500 m and 8000 m), is ensured by an increase in pulmonary ventilation, an increase in cardiac output by increasing heart rate, changes in vascular tone, as well as an increase in haemoglobin concentration. BP, blood pressure; HR, heart rate; PaCO2, partial pressure of arterial carbon dioxide. PMID:29340578

Liquidus Phases of the Richardson H5 Chondrite at High Pressures and Temperatures

NASA Technical Reports Server (NTRS)

Channon, M.; Garber, J.; Danielson, L. R.; Righter, K.

2007-01-01

Part of early mantle evolution may include a magma ocean, where core formation began before the proto-Earth reached half of its present radius. Temperatures were high and bombardment and accretion were still occurring, suggesting that the proto-Earth consisted of a core and an at least partially liquid mantle, the magma ocean. As the Earth accreted, pressure near the core increased and the magma ocean decreased in volume and became shallower as it began to cool and solidify. As crystals settled, or floated, the composition of the magma ocean could change significantly and begin to crystallize different minerals from the residual liquid. Therefore, the mantle may be stratified following the P-T phase diagram for the bulk silicate Earth. To understand mantle evolution, it is necessary to know liquidus phase relations at high pressures and temperatures. In order to model the evolution of the magma ocean, high pressure and temperature experiments have been conducted to simulate the crystallization process using a range of materials that most likely resemble the bulk composition of the early Earth.

Electrospray-printed nanostructured graphene oxide gas sensors

NASA Astrophysics Data System (ADS)

Taylor, Anthony P.; Velásquez-García, Luis F.

2015-12-01

We report low-cost conductometric gas sensors that use an ultrathin film made of graphene oxide (GO) nanoflakes as transducing element. The devices were fabricated by lift-off metallization and near-room temperature, atmospheric pressure electrospray printing using a shadow mask. The sensors are sensitive to reactive gases at room temperature without requiring any post heat treatment, harsh chemical reduction, or doping with metal nanoparticles. The sensors’ response to humidity at atmospheric pressure tracks that of a commercial sensor, and is linear with changes in humidity in the 10%-60% relative humidity range while consuming <6 μW. Devices with GO layers printed by different deposition recipes yielded nearly identical response characteristics, suggesting that intrinsic properties of the film control the sensing mechanism. The gas sensors successfully detected ammonia at concentrations down to 500 ppm (absolute partial pressure of ˜5 × 10-4 T) at ˜1 T pressure, room temperature conditions. The sensor technology can be used in a great variety of applications including air conditioning and sensing of reactive gas species in vacuum lines and abatement systems.

Electrospray-printed nanostructured graphene oxide gas sensors.

PubMed

Taylor, Anthony P; Velásquez-García, Luis F

2015-12-18

We report low-cost conductometric gas sensors that use an ultrathin film made of graphene oxide (GO) nanoflakes as transducing element. The devices were fabricated by lift-off metallization and near-room temperature, atmospheric pressure electrospray printing using a shadow mask. The sensors are sensitive to reactive gases at room temperature without requiring any post heat treatment, harsh chemical reduction, or doping with metal nanoparticles. The sensors' response to humidity at atmospheric pressure tracks that of a commercial sensor, and is linear with changes in humidity in the 10%-60% relative humidity range while consuming <6 μW. Devices with GO layers printed by different deposition recipes yielded nearly identical response characteristics, suggesting that intrinsic properties of the film control the sensing mechanism. The gas sensors successfully detected ammonia at concentrations down to 500 ppm (absolute partial pressure of ∼5 × 10(-4) T) at ∼1 T pressure, room temperature conditions. The sensor technology can be used in a great variety of applications including air conditioning and sensing of reactive gas species in vacuum lines and abatement systems.

LIF measurements and chemical kinetic analysis of methylidyne formation in high-pressure counter-flow partially premixed and non-premixed flames

NASA Astrophysics Data System (ADS)

Naik, S. V.; Laurendeau, N. M.

2004-11-01

We report quantitative, spatially resolved, linear laser-induced fluorescence (LIF) measurements of methylidyne concentration ([CH]) in laminar, methane air, counter-flow partially premixed and non-premixed flames using excitation near 431.5 nm in the A X (0,0) band. For partially premixed flames, fuel-side equivalence ratios (ϕB) of 1.45, 1.6 and 2.0 are studied at pressures of 1, 3, 6, 9 and 12 atm. For non-premixed flames, the fuel-side mixture consists of 25% CH4 and 75% N2; measurements are obtained at pressures of 1, 2, 3, 4, 5, 6, 9 and 12 atm. The quantitative CH measurements are compared with predictions from an opposed-flow flame code utilizing two GRI chemical kinetic mechanisms (versions 2.11 and 3.0). LIF measurements of [CH] are corrected for variations in the quenching rate coefficient by using major species concentrations and temperatures generated by the code along with suitable quenching cross sections for CH available from the literature. A pathway analysis provides relative contributions from important elementary reactions to the total amount of CH produced at various pressures. Key reactions controlling peak CH concentrations are also identified by using a sensitivity analysis. For the partially premixed flames, measured CH profiles are reproduced reasonably well by GRI 3.0, although some quantitative disagreement exists at all pressures. Two CH radical peaks are observed for ϕB=1.45 and ϕB=1.6 at pressures above 3 atm. Peak CH concentrations for the non-premixed flames are significantly underpredicted by GRI 3.0. The latter agrees with previously reported NO concentrations, which are also underpredicted in these same high-pressure counter-flow diffusion flames.

Introduction to total- and partial-pressure measurements in vacuum systems

NASA Technical Reports Server (NTRS)

Outlaw, R. A.; Kern, F. A.

1989-01-01

An introduction to the fundamentals of total and partial pressure measurement in the vacuum regime (760 x 10 to the -16th power Torr) is presented. The instrument most often used in scientific fields requiring vacuum measurement are discussed with special emphasis on ionization type gauges and quadrupole mass spectrometers. Some attention is also given to potential errors in measurement as well as calibration techniques.

A negative feedback mechanism for the long-term stabilization of the earth's surface temperature

NASA Technical Reports Server (NTRS)

Walker, J. C. G.; Hays, P. B.; Kasting, J. F.

1981-01-01

It is suggested that the partial pressure of carbon dioxide in the atmosphere is buffered, over geological time scales, by a negative feedback mechanism, in which the rate of weathering of silicate minerals (followed by deposition of carbonate minerals) depends on surface temperature, which in turn depends on the carbon dioxide partial pressure through the greenhouse effect. Although the quantitative details of this mechanism are speculative, it appears able to partially stabilize the earth's surface temperature against the steady increase of solar luminosity, believed to have occurred since the origin of the solar system.

Design development and test: Two-gas atmosphere control subsystem

NASA Technical Reports Server (NTRS)

Jackson, J. K.

1974-01-01

An atmosphere control subsystem (ACS) was developed for NASA-IBJSC which is designed to measure the major atmospheric constituents in the manned cabin of the space shuttle orbiter and control the addition of oxygen and nitrogen to maintain the partial pressures of these gases within very close limits. The ACS includes a mass spectrometer sensor (MSS) which analyzes the atmosphere of a shuttle vehicle pressurized cabin, and an electronic control assembly (ECA). The MSS was built and tested to meet the requirements for flight equipment for the M-171 Metabolic Analyzer experiment for the Skylab flight program. The instrument analyzes an atmospheric gas sample and produces continuous 0-5 vdc analog signals proportional to the partial pressures of H2, O2, N2, H2O, CO2 and total hydrocarbons having a m/e ratio between 50 and 120. It accepts signals from the MSS proportional to the partial pressures of N2 and O2 and controls the supply of these gases to the closed cabin.

Preflight studies on tolerance of pocket mice to oxygen and heat. IV - Observations on the brain

NASA Technical Reports Server (NTRS)

Bailey, O. T.; Ordy, J. M.; Haymaker, W.

1975-01-01

Experiments designed to ascertain the effects of oxygen at 8, 10, and 12 psi partial pressure on the brains of pocket mice (Perognathus longimembris) were carried out at room temperature (24 C, 75 F) and at 32 C (90 F). The animals exposed to 8-12 psi at 32 C had been in earlier KO2 oxygen tests. Five animals exposed either to 10 or 12 psi (517 mm or 620 mm Hg) O2 partial pressure at 32 C died during the course of the tests, possibly as a consequence of injury sustained by the earlier O2 partial pressure testing. Autopsy was not carried out. In the other 36 exposed animals, no pathological changes were observed in the brain. It is thus highly probable that oxygen pressures at the hyperbaric levels to which the pocket mice would be exposed during the Apollo XVII mission would not result in any lesions in the brain.

An ion interaction model for the volumetric properties of natural waters: Density of the solution and partial molal volumes of electrolytes to high concentrations at 25°C

NASA Astrophysics Data System (ADS)

Monnin, Christophe

1989-06-01

Literature density data for binary and common ion ternary solutions in the Na-K-Ca-Mg-Cl-SO 4-HCO 3-CO3-H 2O system at 25°C have been analysed with Pitzer's ion interaction model, which provides an adequate representation of the experimental data for binary and common ion ternary solutions up to high concentration. This analysis yields Pitzer's interaction parameters for the apparent and partial molal volumes, which are the first derivatives with respect to pressure of the interaction parameters for the free energy. From this information, densities of natural waters as well as partial molal volumes of their solutes can be predicted with good accuracy, as shown by several comparisons of calculated and measured values. It is shown that V¯MX - V¯0mx, the excess partial molal volume of the salt MX, depends more on the type of salt than on the electrolyte itself and that it increases with the charges of the salt components. The influence of concentration and composition on the variation of activity coefficients with pressure and on the partial molal volumes of the salts is discussed, using as an example the partial molal volume of CaSO 4(aq) in solutions of various compositions. The increase of V¯CaSO 4, with ionic strength is very large but is not very different for a NaCl-dominated natural water like the Red Sea lower brine than for a simple NaCl solution. Although the variation of activity coefficients with pressure is usually ignored for moderate pressures, like those found in hydrothermal environments, the present example shows that it can be as large as 30% for a 2-2 salt for a pressure increase from 1 to 500 bars at high ionic strength.

Study of Chromium Oxide Activities in EAF Slags

NASA Astrophysics Data System (ADS)

Yan, Baijun; Li, Fan; Wang, Hui; Sichen, Du

2016-02-01

The activity coefficients of chromium in Cu-Cr melts were determined by equilibrating liquid copper with solid Cr2O3 in CO-CO2 atmosphere. The temperature dependence of the activity coefficients of chromium in Cu-Cr melts could be expressed as lg γ_{Cr}(s)^{0} = { 3 2 5 9( ± 1 8 6} )/T - 0. 5 9( { ± 0. 1} ). Based on the above results, the activities of bivalent and trivalent chromium oxide in some slags at 1873 K (1600 °C) were measured. The slags were equilibrated with Cu-Cr melts under two oxygen partial pressures ( {p_{O}_{ 2} }} } = 6.9 × 10-4 and 1.8 × 10-6 Pa, respectively). The morphology of the quenched slags and the solubility of chromium oxide in the melts were investigated by EPMA, SEM, and XRD. Under both oxygen partial pressures, the slags were saturated by the solid solution MgAl2- x Cr x O4- δ . At the low oxygen partial pressure (1.8 × 10-6 Pa), the content of Cr in the liquid phase varied from 0.4 to 1.6 mass pct with the total Cr content in the slags increasing from 1.3 to 10.8 mass pct. At the high oxygen partial pressure (6.9 × 10-4 Pa), the content of Cr in the liquid phase decreased to the level of 0.2 to 0.6 mass pct. Both the activities of CrO and Cr2O3 in slag were found to increase approximately linearly with the increase of the total Cr content in slag. While the oxygen partial pressure had minor effect on the activity of Cr2O3 in the slag, it had significant effect on the activity of CrO.

Oxygen supply in aquatic ectotherms: partial pressure and solubility together explain biodiversity and size patterns.

PubMed

Verberk, Wilco C E P; Bilton, David T; Calosi, Piero; Spicer, John I

2011-08-01

Aquatic ectotherms face the continuous challenge of capturing sufficient oxygen from their environment as the diffusion rate of oxygen in water is 3 x 10(5) times lower than in air. Despite the recognized importance of oxygen in shaping aquatic communities, consensus on what drives environmental oxygen availability is lacking. Physiologists emphasize oxygen partial pressure, while ecologists emphasize oxygen solubility, traditionally expressing oxygen in terms of concentrations. To resolve the question of whether partial pressure or solubility limits oxygen supply in nature, we return to first principles and derive an index of oxygen supply from Fick's classic first law of diffusion. This oxygen supply index (OSI) incorporates both partial pressure and solubility. Our OSI successfully explains published patterns in body size and species across environmental clines linked to differences in oxygen partial pressure (altitude, organic pollution) or oxygen solubility (temperature and salinity). Moreover, the OSI was more accurately and consistently related to these ecological patterns than other measures of oxygen (oxygen saturation, dissolved oxygen concentration, biochemical oxygen demand concentrations) and similarly outperformed temperature and altitude, which covaried with these environmental clines. Intriguingly, by incorporating gas diffusion rates, it becomes clear that actually more oxygen is available to an organism in warmer habitats where lower oxygen concentrations would suggest the reverse. Under our model, the observed reductions in aerobic performance in warmer habitats do not arise from lower oxygen concentrations, but instead through organismal oxygen demand exceeding supply. This reappraisal of how organismal thermal physiology and oxygen demands together shape aerobic performance in aquatic ectotherms and the new insight of how these components change with temperature have broad implications for predicting the responses of aquatic communities to ongoing global climate shifts.

Boiling regimes of impacting drops on a heated substrate under reduced pressure

NASA Astrophysics Data System (ADS)

van Limbeek, Michiel A. J.; Hoefnagels, Paul B. J.; Shirota, Minori; Sun, Chao; Lohse, Detlef

2018-05-01

We experimentally investigate the boiling behavior of impacting ethanol drops on a heated smooth sapphire substrate at pressures ranging from P =0.13 bar to atmospheric pressure. We employ frustrated total internal reflection imaging to study the wetting dynamics of the contact between the drop and the substrate. The spreading drop can be in full contact (contact boiling), it can partially touch (transition boiling), or the drop can be fully levitated (Leidenfrost boiling). We show that the temperature of the boundary between contact and transition boiling shows at most a weak dependence on the impact velocity, but a significant decrease with decreasing ambient gas pressure. A striking correspondence is found between the temperature of this boundary and the static Leidenfrost temperature for all pressures. We therefore conclude that both phenomena share the same mechanism and are dominated by the dynamics taking place at the contact line. On the other hand, the boundary between transition boiling and Leidenfrost boiling, i.e., the dynamic Leidenfrost temperature, increases for increasing impact velocity for all ambient gas pressures. Moreover, the dynamic Leidenfrost temperature coincides for pressures between P =0.13 and 0.54 bar, whereas for atmospheric pressure the dynamic Leidenfrost temperature is slightly elevated. This indicates that the dynamic Leidenfrost temperature is at most weakly dependent on the enhanced evaporation by the lower saturation temperature of the liquid.

The chemical energy unit partial oxidation reactor operation simulation modeling

NASA Astrophysics Data System (ADS)

Mrakin, A. N.; Selivanov, A. A.; Batrakov, P. A.; Sotnikov, D. G.

2018-01-01

The chemical energy unit scheme for synthesis gas, electric and heat energy production which is possible to be used both for the chemical industry on-site facilities and under field conditions is represented in the paper. The partial oxidation reactor gasification process mathematical model is described and reaction products composition and temperature determining algorithm flow diagram is shown. The developed software product verification showed good convergence of the experimental values and calculations according to the other programmes: the temperature determining relative discrepancy amounted from 4 to 5 %, while the absolute composition discrepancy ranged from 1 to 3%. The synthesis gas composition was found out practically not to depend on the supplied into the partial oxidation reactor (POR) water vapour enthalpy and compressor air pressure increase ratio. Moreover, air consumption coefficient α increase from 0.7 to 0.9 was found out to decrease synthesis gas target components (carbon and hydrogen oxides) specific yield by nearly 2 times and synthesis gas target components required ratio was revealed to be seen in the water vapour specific consumption area (from 5 to 6 kg/kg of fuel).

Computation of transonic flow past projectiles at angle of attack

NASA Technical Reports Server (NTRS)

Reklis, R. P.; Sturek, W. B.; Bailey, F. R.

1978-01-01

Aerodynamic properties of artillery shell such as normal force and pitching moment reach peak values in a narrow transonic Mach number range. In order to compute these quantities, numerical techniques have been developed to obtain solutions to the three-dimensional transonic small disturbance equation about slender bodies at angle of attack. The computation is based on a plane relaxation technique involving Fourier transforms to partially decouple the three-dimensional difference equations. Particular care is taken to assure accurate solutions near corners found in shell designs. Computed surface pressures are compared to experimental measurements for circular arc and cone cylinder bodies which have been selected as test cases. Computed pitching moments are compared to range measurements for a typical projectile shape.

Measurement of Local Partial Pressure of Oxygen in the Brain Tissue under Normoxia and Epilepsy with Phosphorescence Lifetime Microscopy

PubMed Central

Zhang, Cong; Bélanger, Samuel; Pouliot, Philippe; Lesage, Frédéric

2015-01-01

In this work a method for measuring brain oxygen partial pressure with confocal phosphorescence lifetime microscopy system is reported. When used in conjunction with a dendritic phosphorescent probe, Oxyphor G4, this system enabled minimally invasive measurements of oxygen partial pressure (pO2) in cerebral tissue with high spatial and temporal resolution during 4-AP induced epileptic seizures. Investigating epileptic events, we characterized the spatio-temporal distribution of the "initial dip" in pO2 near the probe injection site and along nearby arterioles. Our results reveal a correlation between the percent change in the pO2 signal during the "initial dip" and the duration of seizure-like activity, which can help localize the epileptic focus and predict the length of seizure. PMID:26305777

Gas concentration measurement instrument based on the effects of a wave-mixing interference on stimulated emissions

DOEpatents

Garrett, W. Ray

1997-01-01

A method and apparatus for measuring partial pressures of gaseous components within a mixture. The apparatus comprises generally at least one tunable laser source, a beam splitter, mirrors, optical filter, an optical spectrometer, and a data recorder. Measured in the forward direction along the path of the laser, the intensity of the emission spectra of the gaseous component, at wavelengths characteristic of the gas component being measured, are suppressed. Measured in the backward direction, the peak intensities characteristic of a given gaseous component will be wavelength shifted. These effects on peak intensity wavelengths are linearly dependent on the partial pressure of the compound being measured, but independent of the partial pressures of other gases which are present within the sample. The method and apparatus allow for efficient measurement of gaseous components.

Gas concentration measurement instrument based on the effects of a wave-mixing interference on stimulated emissions

DOEpatents

Garrett, W.R.

1997-11-11

A method and apparatus are disclosed for measuring partial pressures of gaseous components within a mixture. The apparatus comprises generally at least one tunable laser source, a beam splitter, mirrors, optical filter, an optical spectrometer, and a data recorder. Measured in the forward direction along the path of the laser, the intensity of the emission spectra of the gaseous component, at wavelengths characteristic of the gas component being measured, are suppressed. Measured in the backward direction, the peak intensities characteristic of a given gaseous component will be wavelength shifted. These effects on peak intensity wavelengths are linearly dependent on the partial pressure of the compound being measured, but independent of the partial pressures of other gases which are present within the sample. The method and apparatus allow for efficient measurement of gaseous components. 9 figs.

Isochoric Burn, an Internally Consistent Method for the Reactant to Product Transformation in Reactive Flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reaugh, J E; Lee, E L

2002-07-01

Mixture rules for partially reacted explosives differ amongst various models. For instance, JWL++ uses a partial pressure addition to compute an average zonal pressure, Ignition and Growth requires pressure equilibration and thermal equilibration of temperature dependent JWL EOSs, CHEETAH In Line RF also assumes temperature and pressure equilibration. It has been suggested in the past that a more realistic equilibration scheme should comprise isentropic pressure equilibration of the separate reacted and unreacted phases. This turns out not to be a proper path for equilibration. Rather, we find that the only internally consistent method is the evaluation of the equilibrium pressuremore » that satisfies the particular conditions of reactant and product resulting from deflagration in a fixed volume.« less

Shock effects on hydrous minerals and implications for carbonaceous meteorites

NASA Technical Reports Server (NTRS)

Lange, M. A.; Ahrens, T. J.; Lambert, P.

1985-01-01

The effect of shock loading over the pressure range of 29-59 GPa on the shock-recovered specimens of antigorite serpentine, Mg3Si2O5(OH)4, were investigated employing infrared (IR) spectroscopy, thermogravimetric analysis, and optical and scanning electron microscopy. With increasing shock pressure, there was an increase in H2O IR absorption peaks at the expense of OH peaks, while the changes in SiO bond vibration modes were identical to those seen for other, nonhydrous minerals. Thermogravimetric results on vented assembly samples showed linear relationships between the shock pressure and both the length of dehydration interval and the effective activation energy for releasing post-shock structural water. Optical and scanning electron microscopy revealed gas bubbles, which appeared to be injected into zones of partial melting, and vesicular dark veins distributed throughout the shocked samples. It is suggested that shock loading of hydrous minerals would release and redistribute free water in the regoliths of carbonaceous chondrite parent bodies, giving rise to observed hydrous alterations.

Vaporization of liquid Pb-Li eutectic alloy from 1000K to 1200K - A high temperature mass spectrometric study

NASA Astrophysics Data System (ADS)

Jain, U.; Mukherjee, A.; Dey, G. K.

2017-09-01

Liquid lead-lithium eutectic will be used as a coolant in fusion reactor blanket loop. Vapor pressure of the eutectic is an important parameter to accurately predict its in-loop behavior. Past measurements of vapor pressure of the eutectic relied on indirect methods. In this paper, we report for the first time the in-situ vaporization behavior of the liquid alloy between 1042 and 1176 K by Knudsen effusion mass spectrometry (KEMS). It was seen that the vaporization occurred by independent evaporation of lead and lithium. No complex intermetallic vapor was seen in the mass spectra. The partial pressures and enthalpy of vaporization of Pb and Li were evaluated directly from the measured ion intensities formed from the equilibrium vapor over the alloy. The activity of Li over a temperature range of 1042-1176 K was found to be 4.8 × 10-5 to that of pure Li, indicating its very low activity in the alloy.

Precise new shock temperatures in forsterite and in silicate liquids: phase transitions and heat capacity at high pressure

NASA Astrophysics Data System (ADS)

Asimow, P. D.; Fat'yanov, O. V.; Su, C.; Ma, X. J.

2017-12-01

Shock temperature measurements in transparent samples provide key constraints on the phase transitions and thermodynamic properties of materials at high pressure and temperature. Such measurements are necessary, for example, to allow equation of state measurements taken along the Hugoniot to be translated to P-V-T space. We have recently completed a detailed study of the accuracy and reproducibility of calibration of our 6-channel fast pyrometer. We have also introduced improved analysis procedures of the time-dependent multi-wavelength radiance signal that avoid the need for a greybody assumption and therefore have better precision than earlier results. This has motivated (a) renewed study of the shock temperature of forsterite in the superheating, partial melting, and complete melting regimes, (b) pre-heated diopside-anorthite glass shock temperature experiments for comparison to pre-heated silicate liquid equation of state results, and (c) new soda-lime glass shock temperature experiments. Single-crystal synthetic forsterite samples were shocked along (100) to pressures between 120 and 210 GPa on the Caltech two-stage light gas gun. Uncertainties on most results are 50 K. Results above the onset of partial melting at 130 GPa are consistent with Lyzenga and Ahrens (1980) data and show a low P-T slope consistent with a partial melting interval. Complete melting may occur, given sufficient time, at about 210 GPa. The experiment at 120-130 GPa is anomalous, showing two-wave structure and time- and wavelength-dependent scattering suggesting a subsolidus phase transition behind the shock front. The amount of super-heating, if any, is far smaller than claimed by Holland and Ahrens (1997). Steady radiation profiles, high emissivity, and consistency from channel to channel provide high precision (±40 K) in diopside-anorthite liquid shocked from just above the glass transition to high pressure. Temperatures are colder than expected for a model with constant heat capacity, providing direct evidence that multicomponent silicate liquids show a major increase in heat capacity in the P-T range appropriate to terrestrial magma oceans (<150 GPa, <5000 K).

Thermodynamic equilibrium calculations of hydrogen production from the combined processes of dimethyl ether steam reforming and partial oxidation

NASA Astrophysics Data System (ADS)

Semelsberger, Troy A.; Borup, Rodney L.

Thermodynamic analyses of producing a hydrogen-rich fuel-cell feed from the combined processes of dimethyl ether (DME) partial oxidation and steam reforming were investigated as a function of oxygen-to-carbon ratio (0.00-2.80), steam-to-carbon ratio (0.00-4.00), temperature (100 °C-600 °C), pressure (1-5 atm) and product species. Thermodynamically, dimethyl ether processed with air and steam generates hydrogen-rich fuel-cell feeds; however, the hydrogen concentration is less than that for pure DME steam reforming. Results of the thermodynamic processing of dimethyl ether indicate the complete conversion of dimethyl ether to hydrogen, carbon monoxide and carbon dioxide for temperatures greater than 200 °C, oxygen-to-carbon ratios greater than 0.00 and steam-to-carbon ratios greater than 1.25 at atmospheric pressure (P = 1 atm). Increasing the operating pressure has negligible effects on the hydrogen content. Thermodynamically, dimethyl ether can produce concentrations of hydrogen and carbon monoxide of 52% and 2.2%, respectively, at a temperature of 300 °C, and oxygen-to-carbon ratio of 0.40, a pressure of 1 atm and a steam-to-carbon ratio of 1.50. The order of thermodynamically stable products (excluding H 2, CO, CO 2, DME, NH 3 and H 2O) in decreasing mole fraction is methane, ethane, isopropyl alcohol, acetone, n-propanol, ethylene, ethanol and methyl-ethyl ether; trace amounts of formaldehyde, formic acid and methanol are observed. Ammonia and hydrogen cyanide are also thermodynamically favored products. Ammonia is favored at low temperatures in the range of oxygen-to-carbon ratios of 0.40-2.50 regardless of the steam-to-carbon ratio employed. The maximum ammonia content (i.e., 40%) occurs at an oxygen-to-carbon ratio of 0.40, a steam-to-carbon ratio of 1.00 and a temperature of 100 °C. Hydrogen cyanide is favored at high temperatures and low oxygen-to-carbon ratios with a maximum of 3.18% occurring at an oxygen-to-carbon ratio of 0.40 and a steam-to-carbon ratio of 0.00 in the temperature range of 400 °C-500 °C. Increasing the system pressure shifts the equilibrium toward ammonia and hydrogen cyanide.

Feasibility of Lettuce Growth at Hypoxic and Sub-Ambient Total Gas Pressures

NASA Technical Reports Server (NTRS)

Hoffman, Anne

1997-01-01

Lettuce (Lactuca saliva L. cv. 'Waldmann's Green') plants were grown (1) either from seed to 5 days old to study the effect of low atmospheric pressure (70 kPa) on their germination and early growth, or (2) until maturity at 30 days old to determine any long-term growth effects. The data were compared to plants grown in a second matching chamber which was maintained at ambient pressure (101 kPa) that served as a control. In other experiments, plants were grown at ambient pressure until maturity and then subjected to low atmospheric pressure for periods of 24 hours to determine possible effects of intermittent low pressure. The O2 and CO2 partial pressures in the low pressure chamber were adjusted to levels equal to those in the ambient pressure chamber to prevent differences in plant response which would have resulted from differences in the partial pressure of those gasses. The O2 partial pressure in the ambient chamber was maintained at 21 kPa and provision was made for additional CO2 during the fight phase. The germination rate and early seedling growth were insensitive to a low pressure environment. The rate of root elongation of plants grown at 70 kPa and at 101 kPa was also approximately the same. The rate of net carbon assimilation (per unit leaf area) of plants grown at low atmospheric pressure was unaffected at all growth stages even though plants grown at 70 kPa had slightly greater fresh and dry weights. There were consistent differences in assimilate partitioning, as shown by higher root/shoot ratios of plants grown at low pressure. Transpiration rates of plants grown until maturity under either constant or intermittent low pressure were reduced. Dark respiration rates of plants grown until maturity under either constant or intermittent low pressure were approximately 20% higher than the control plants.

The erosion/corrosion of small superalloy turbine rotors operating in the effluent of a PFB coal combustor

NASA Technical Reports Server (NTRS)

Zellars, G. R.; Benfold, S. M.; Rowe, A. P.; Lowell, C. E.

1979-01-01

Superalloy turbine rotors in a single stage turbine with 6 percent partial admittance were operated in the effluent of a pressurized fluidized bed coal combustor for up to 164 hours. Total mass flow was 300 kg/hr and average particulate loadings ranged from 600 to 2800 ppm for several coal/sorbent combinations. A 5.5 atm turbine inlet gas pressure and inlet gas temperatures from 700 to 800 C yielded absolute gas velocities at the stator exit of about 500 m/s. The angular rotation speed (40,000 rpm) of the six inch diameter rotors was equivalent to a tip speed of about 300 m/s, and average gas velocities relative to the rotating surface ranged from 260 to 330 m/s at mean radius. The rotor erosion pattern reflects heavy particle separation with severe (5 to 500 cm/yr) erosion at the leading edge, pressure side center, and suction side trailing edge at the tip. The erosion distribution pattern provides a spectrum of erosion/oxidation/deposition as a function of blade position. This spectrum includes enhanced oxidation (10 to 100 x air), mixed oxides in exposed depletion zones, sulfur rich oxides in deposition zones, and rugged areas of erosive oxide removal.

Internal friction quality-factor Q under confining pressure. [of lunar rocks

NASA Technical Reports Server (NTRS)

Tittmann, B. R.; Ahlberg, L.; Nadler, H.; Curnow, J.; Smith, T.; Cohen, E. R.

1977-01-01

It has been found in previous studies that small amounts of adsorbed volatiles can have a profound effect on the internal friction quality-factor Q of rocks and other porous media. Pandit and Tozer (1970) have suggested that the laboratory-measured Q of volatile-free rocks should be similar to the in situ seismic Q values of near-surface lunar rocks which according to Latham et al. (1970) are in the range of 3000-5000. Observations of dramatic increases in Q with outgassing up to values approaching 2000 in the seismic frequency range confirm this supposition. Measurements under confining pressures with the sample encapsulated under hard vacuum are reported to aid in the interpretation of seismic data obtained below the lunar surface. It has been possible to achieve in the experiments Q values just under 2000 at about 1 kbar for a terrestrial analog of lunar basalt. It was found that a well-outgassed sample maintains a high Q whereas one exposed to moisture maintains a low Q as the confining pressure is raised to 2.5 kbar. This result suggests that volatiles can indeed affect Q when cracks are partially closed and the high lunar seismic Q values reported are concomitant with very dry rock down to depths of at least 50 km.

Filterability of freshly-collected sickle erythrocytes under venous oxygen pressure without exposure to air.

PubMed

Shah, Siddharth; Acholonu, Rhonda Graves; Ohene-Frempong, Kwaku; Asakura, Toshio

2015-12-01

We previously found that blood samples collected from steady-state patients with sickle cell disease (SCD) without exposure to air contain a new type of reversibly sickled cells (RSCs) with blunt edges at a level of as high as 78%. Since partial oxygenation of once-deoxygenated sickled cells with pointy edges to near venous oxygen pressure generates similar sickled cells with blunt edges in vitro, we named them as partially oxygenated sickled cells (POSCs). On the other hand, partial deoxygenation of once-oxygenated SS cells to venous oxygen pressure generates partially deoxygenated sickled cells (PDSCs) with pointy edges. In this study, we obtained blood samples from 6 steady-state patients with SCD under venous oxygen pressure without exposure to air, subjected them to various oxygenation/deoxygenation/reoxygenation cycles, and studied their filterability through a membrane filter with pore diameter of 3μm, the theoretical minimum diameter of a capillary. Our results indicated that discocytes, POSCs with blunt edges, and irreversibly sickled cells could deform and pass through the filter, while PDSCs with pointy edges were rigid and could not. The filterability of SS cells seems to be related to the length and amount of deoxy-hemoglobin S fibers in the cells. Copyright © 2015. Published by Elsevier Inc.

The defect chemistry of UO2 ± x from atomistic simulations

NASA Astrophysics Data System (ADS)

Cooper, M. W. D.; Murphy, S. T.; Andersson, D. A.

2018-06-01

Control of the defect chemistry in UO2 ± x is important for manipulating nuclear fuel properties and fuel performance. For example, the uranium vacancy concentration is critical for fission gas release and sintering, while all oxygen and uranium defects are known to strongly influence thermal conductivity. Here the point defect concentrations in thermal equilibrium are predicted using defect energies from density functional theory (DFT) and vibrational entropies calculated using empirical potentials. Electrons and holes have been treated in a similar fashion to other charged defects allowing for structural relaxation around the localized electronic defects. Predictions are made for the defect concentrations and non-stoichiometry of UO2 ± x as a function of oxygen partial pressure and temperature. If vibrational entropy is omitted, oxygen interstitials are predicted to be the dominant mechanism of excess oxygen accommodation over only a small temperature range (1265 K-1350 K), in contrast to experimental observation. Conversely, if vibrational entropy is included oxygen interstitials dominate from 1165 K to 1680 K (Busker potential) or from 1275 K to 1630 K (CRG potential). Below these temperature ranges, excess oxygen is predicted to be accommodated by uranium vacancies, while above them the system is hypo-stoichiometric with oxygen deficiency accommodated by oxygen vacancies. Our results are discussed in the context of oxygen clustering, formation of U4O9, and issues for fuel behavior. In particular, the variation of the uranium vacancy concentrations as a function of temperature and oxygen partial pressure will underpin future studies into fission gas diffusivity and broaden the understanding of UO2 ± x sintering.

Carbon dioxide partial pressure and 13C content of north temperate and boreal lakes at spring ice melt

USGS Publications Warehouse

Striegl, Robert G.; Kortelainen, Pirkko; Chanton, J.P.; Wickland, K.P.; Bugna, G.C.; Rantakari, M.

2001-01-01

Carbon dioxide (CO2) accumulates under lake ice in winter and degasses to the atmosphere after ice melt. This large springtime CO2 pulse is not typically considered in surface-atmosphere flux estimates, because most field studies have not sampled through ice during late winter. Measured CO2 partial pressure (pCO2) of lake surface water ranged from 8.6 to 4,290 Pa (85-4,230 ??atm) in 234 north temperate and boreal lakes prior to ice melt during 1998 and 1999. Only four lakes had surface pCO2 less than or equal to atmospheric pCO2, whereas 75% had pCO2 >5 times atmospheric. The ??13CDIC (DIC = ??CO2) of 142 of the lakes ranged from -26.28??? to +0.95.???. Lakes with the greatest pCO2 also had the lightest ??13CDIC, which indicates respiration as their primary CO2 source. Finnish lakes that received large amounts of dissolved organic carbon from surrounding peatlands had the greatest pCO2. Lakes set in noncarbonate till and bedrock in Minnesota and Wisconsin had the smallest pCO2 and the heaviest ??13CDIC, which indicates atmospheric and/or mineral sources of C for those lakes. Potential emissions for the period after ice melt were 2.36 ?? 1.44 mol CO2 m-2 for lakes with average pCO2 values and were as large as 13.7 ?? 8.4 mol CO2 m-2 for lakes with high pCO2 values.

Digital Architecture for a Trace Gas Sensor Platform

NASA Technical Reports Server (NTRS)

Gonzales, Paula; Casias, Miguel; Vakhtin, Andrei; Pilgrim, Jeffrey

2012-01-01

A digital architecture has been implemented for a trace gas sensor platform, as a companion to standard analog control electronics, which accommodates optical absorption whose fractional absorbance equivalent would result in excess error if assumed to be linear. In cases where the absorption (1-transmission) is not equivalent to the fractional absorbance within a few percent error, it is necessary to accommodate the actual measured absorption while reporting the measured concentration of a target analyte with reasonable accuracy. This requires incorporation of programmable intelligence into the sensor platform so that flexible interpretation of the acquired data may be accomplished. Several different digital component architectures were tested and implemented. Commercial off-the-shelf digital electronics including data acquisition cards (DAQs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), and microcontrollers have been used to achieve the desired outcome. The most completely integrated architecture achieved during the project used the CPLD along with a microcontroller. The CPLD provides the initial digital demodulation of the raw sensor signal, and then communicates over a parallel communications interface with a microcontroller. The microcontroller analyzes the digital signal from the CPLD, and applies a non-linear correction obtained through extensive data analysis at the various relevant EVA operating pressures. The microcontroller then presents the quantitatively accurate carbon dioxide partial pressure regardless of optical density. This technique could extend the linear dynamic range of typical absorption spectrometers, particularly those whose low end noise equivalent absorbance is below one-part-in-100,000. In the EVA application, it allows introduction of a path-length-enhancing architecture whose optical interference effects are well understood and quantified without sacrificing the dynamic range that allows quantitative detection at the higher carbon dioxide partial pressures. The digital components are compact and allow reasonably complete integration with separately developed analog control electronics without sacrificing size, mass, or power draw.

Effects of hypobaria and hypoxia on seed germination of six plant species

NASA Astrophysics Data System (ADS)

Tang, Yongkang; Gao, Feng; Guo, Shuangsheng; Li, Fang

2014-10-01

Hypobaria (low pressure) is typically associated with hypoxia (low oxygen partial pressure). There are several advantages of growing higher plants under hypobaria in the moon or mars habitat. The objectives of this research were to investigate the seed germination of six plant species under hypobaric and ambient total pressure conditions. Seeds were sown and germinated under three levels of total atmospheric pressure (101, 30 and 10 kPa) and three levels of oxygen partial pressures (21, 6 and 2 kPa) in an 8-day study. Hypoxia (6 or 2 kPa) significantly inhibited all seed germination under three levels of total atmospheric pressure by increasing the electrical conductivity and the optical density, decreasing the seed germination percentage and seed dehydrogenase activity and inhibiting the growth of the shoots and roots. Hypobaria (30 or 10 kPa) markedly improved seed germination and root growth by enhancing the oxygen diffusion rate under hypoxic conditions (6 or 2 kPa). The seeds of three dicot plants (lettuce, Chinese cabbage and cucumber) were more sensitive to hypoxia caused by hypobaria than were those of three monocot plants (maize, wheat and rice); lettuce and cucumber seeds had the highest sensitivity, whereas rice seeds had the lowest sensitivity. This research demonstrates that six experimental seeds can germinate normally under hypobaria (30 kPa), but the oxygen partial pressure should not be less than 6 kPa.

Calculation of three dimensional viscous flows in annular cascades using parabolized Navier-Stokes equations

NASA Astrophysics Data System (ADS)

Lawerenz, M.

Numerical algorithms for describing the endwall boundary layers and secondary flows in high turning turbine cascades are described. Partially-parabolic methods which cover three-dimensional viscous flow effects are outlined. Introduction of tip-clearance models and modifications of no-slip conditions without the use of wall functions expand the range of application and improve accuracy. Simultaneous computation of the profile boundary layers by refinement of the mesh size in the circumferential direction makes it possible to describe the boundary layer interaction in the corners formed by the bladings and the endwalls. The partially-parabolic method means that the streamwise elliptic coupling is well represented by the given pressure field and that separation does not occur, but it is not possible to describe the separation of the endwall boundary layer near the leading edge and the horse-shoe vortex there properly.

Preprototype independent air revitalization subsystem

NASA Technical Reports Server (NTRS)

Schubert, F. H.; Hallick, T. M.; Woods, R. R.

1982-01-01

The performance and maturity of a preprototype, three-person capacity, automatically controlled and monitored, self-contained independent air revitalization subsystem were evaluated. The subsystem maintains the cabin partial pressure of oxygen at 22 kPa (3.2 psia) and that of carbon dioxide at 400 Pa (3 mm Hg) over a wide range of cabin air relative humidity conditions. Consumption of water vapor by the water vapor electrolysis module also provides partial humidity control of the cabin environment. During operation, the average carbon dioxide removal efficiency at baseline conditions remained constant throughout the test at 84%. The average electrochemical depolarized concentrator cell voltage at the end of the parametric/endurance test was 0.41 V, representing a very slowly decreasing average cell voltage. The average water vapor electrolysis cell voltage increased only at a rate of 20 mu/h from the initial level of 1.67 V to the final level of 1.69 V at conclusion of the testing.

The effect of pressure on the structural, electronic, magnetic, and thermodynamic properties of the Mn2RuGe inverse Heusler alloy

NASA Astrophysics Data System (ADS)

Song, Ting; Sun, Xiao-Wei; Tian, Jun-Hong; Wei, Xiao-Ping; Wan, Gui-Xin; Ma, Qin

2017-04-01

In the frame of density functional theory, first-principles calculations based on generalized gradient approximation and quasi-harmonic Debye approximation model in which the phononic effects are taken into account have been carried out to investigate the structural, electronic, magnetic, and thermodynamic properties of full-Heusler alloy Mn2RuGe in CuHg2Ti-type structure in the pressure range of 0-50 GPa. Present calculations predict that Mn2RuGe is a ferrimagnet with an optimized lattice parameter of 5.854 Å. The calculated total magnetic moment of 2.01 μB per formula unit is very close to integer value and agree well with the Slater-Pauling rule, where the partial spin moments of Mn (A) and Mn (B) which mainly contribute to the total magnetic moment are 2.66 μB and -0.90 μB, respectively. In the study of the energy band structures and density of states, Mn2RuGe exhibits half-metallicity with an indirect gap of 0.235 eV in the spin-down channels, and the shifting of bands towards higher energies in spin-down channel under high pressure. Meanwhile, the high-pressure thermodynamic properties of Mn2RuGe, such as the pressure-volume-temperature relationship, bulk modulus, thermal expansivity, heat capacity, Debye temperature, and Grüneisen parameter are evaluated systematically in the temperature range of 0-900 K. This set of data is considered as the useful information to understand the high-pressure and high-temperature properties for the Mn2RuZ-type Heusler alloy family.

Melt-Vapor Phase Diagram of the Te-S System

NASA Astrophysics Data System (ADS)

Volodin, V. N.; Trebukhov, S. A.; Kenzhaliyev, B. K.; Nitsenko, A. V.; Burabaeva, N. M.

2018-03-01

The values of partial pressure of saturated vapor of the constituents of the Te-S system are determined from boiling points. The boundaries of the melt-vapor phase transition at atmospheric pressure and in vacuum of 2000 and 100 Pa are calculated on the basis of partial pressures. A phase diagram that includes vapor-liquid equilibrium fields whose boundaries allow us to assess the behavior of elements upon distillation fractioning is plotted. It is established that the separation of elements is possible at the first evaporation-condensation cycle. Complications can be caused by crystallization of a sulfur solid solution in tellurium.

Dynamic calibration of fast-response probes in low-pressure shock tubes

NASA Astrophysics Data System (ADS)

Persico, G.; Gaetani, P.; Guardone, A.

2005-09-01

Shock tube flows resulting from the incomplete burst of the diaphragm are investigated in connection with the dynamic calibration of fast-response pressure probes. As a result of the partial opening of the diaphragm, pressure disturbances are observed past the shock wave and the measured total pressure profile deviates from the envisaged step signal required by the calibration process. Pressure oscillations are generated as the initially normal shock wave diffracts from the diaphragm's orifice and reflects on the shock tube walls, with the lowest local frequency roughly equal to the ratio of the sound speed in the perturbed region to the shock tube diameter. The energy integral of the perturbations decreases with increasing distance from the diaphragm, as the diffracted leading shock and downwind reflections coalesce into a single normal shock. A procedure is proposed to calibrate fast-response pressure probes downwind of a partially opened shock tube diaphragm.

Olivine and chromian spinel in primitive calc-alkaline and tholeiitic lavas from the southernmost cascade range, California: A reflection of relative fertility of the source

USGS Publications Warehouse

Clynne, M.A.; Borg, L.E.

1997-01-01

Chromian spinel and coexisting olivine phenocrysts from a geochemically diverse suite of primitive tholeiitic and calc-alkaline basalts and magnesian andesites from the Lassen region, in the southernmost Cascade Range, in California, show that the sub-arc mantle is zoned. Depleted calc-alkaline basalts and magnesian andesites erupt in the forearc region, and calc-alkaline basalts contain increasing abundances of incompatible elements toward the backarc. High-alumina olivine tholeiites erupt from the arc and backarc areas. Olivine from all these lavas displays a limited compositional range, from Fo86 to Fo91, and crystallized at high temperature, generally 1225-1275??C. Chromian spinel trapped in the olivine phenocrysts displays a large range of composition: Cr# values span the range 9-76. Excess Al in the spinel relative to that in 1-atm spinel suggests that it crystallized at elevated pressure. The phenocrysts in these lavas are in equilibrium with their host liquids. The full range of Cr# of the spinel compositions cannot be explained by differentiation or variable pressure, variations in f(O2), subsolidus equilibration or variations in degree of partial melting of a single peridotitic source. Rather, the systematic compositional differences among phenocrysts in these primitive lavas result from bulk chemical variability in their mantle sources. Correlations between spinel and host-rock compositions support the assertion that the geochemical diversity of Lassen basalts reflects the relative fertility of their mantle sources.

Analytical and experimental studies of leak location and environment characterization for the international space station

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woronowicz, Michael; Blackmon, Rebecca; Brown, Martin

2014-12-09

The International Space Station program is developing a robotically-operated leak locator tool to be used externally. The tool would consist of a Residual Gas Analyzer for partial pressure measurements and a full range pressure gauge for total pressure measurements. The primary application is to demonstrate the ability to detect NH{sub 3} coolant leaks in the ISS thermal control system. An analytical model of leak plume physics is presented that can account for effusive flow as well as plumes produced by sonic orifices and thruster operations. This model is used along with knowledge of typical RGA and full range gauge performancemore » to analyze the expected instrument sensitivity to ISS leaks of various sizes and relative locations (“directionality”). The paper also presents experimental results of leak simulation testing in a large thermal vacuum chamber at NASA Goddard Space Flight Center. This test characterized instrument sensitivity as a function of leak rates ranging from 1 lb{sub m/}/yr. to about 1 lb{sub m}/day. This data may represent the first measurements collected by an RGA or ion gauge system monitoring off-axis point sources as a function of location and orientation. Test results are compared to the analytical model and used to propose strategies for on-orbit leak location and environment characterization using the proposed instrument while taking into account local ISS conditions and the effects of ram/wake flows and structural shadowing within low Earth orbit.« less

Partial pressure analysis in space testing

NASA Technical Reports Server (NTRS)

Tilford, Charles R.

1994-01-01

For vacuum-system or test-article analysis it is often desirable to know the species and partial pressures of the vacuum gases. Residual gas or Partial Pressure Analyzers (PPA's) are commonly used for this purpose. These are mass spectrometer-type instruments, most commonly employing quadrupole filters. These instruments can be extremely useful, but they should be used with caution. Depending on the instrument design, calibration procedures, and conditions of use, measurements made with these instruments can be accurate to within a few percent, or in error by two or more orders of magnitude. Significant sources of error can include relative gas sensitivities that differ from handbook values by an order of magnitude, changes in sensitivity with pressure by as much as two orders of magnitude, changes in sensitivity with time after exposure to chemically active gases, and the dependence of the sensitivity for one gas on the pressures of other gases. However, for most instruments, these errors can be greatly reduced with proper operating procedures and conditions of use. In this paper, data are presented illustrating performance characteristics for different instruments and gases, operating parameters are recommended to minimize some errors, and calibrations procedures are described that can detect and/or correct other errors.

Acute pressure on the sciatic nerve results in rapid inhibition of the wide dynamic range neuronal response

PubMed Central

2012-01-01

Background Acute pressure on the sciatic nerve has recently been reported to provide rapid short-term relief of pain in patients with various pathologies. Wide dynamic range (WDR) neurons transmit nociceptive information from the dorsal horn to higher brain centers. In the present study, we examined the effect of a 2-min application of sciatic nerve pressure on WDR neuronal activity in anesthetized male Sprague–Dawley rats. Results Experiments were carried out on 41 male Sprague–Dawley albino rats weighing 160–280 grams. Dorsal horn WDR neurons were identified on the basis of characteristic responses to mechanical stimuli applied to the cutaneous receptive field. Acute pressure was applied for 2 min to the sciatic nerve using a small vascular clip. The responses of WDR neurons to three mechanical stimuli applied to the cutaneous receptive field were recorded before, and 2, 5 and 20 min after cessation of the 2-min pressure application on the sciatic nerve. Two-min pressure applied to the sciatic nerve caused rapid attenuation of the WDR response to pinching, pressure and brushing stimuli applied to the cutaneous receptive field. Maximal attenuation of the WDR response to pinching and pressure was noted 5 min after release of the 2-min pressure on the sciatic nerve. The mean firing rate decreased from 31.7±1.7 Hz to 13±1.4 Hz upon pinching (p < 0.001), from 31.2±2.3 Hz to 10.9±1.4 Hz (p < 0.001) when pressure was applied, and from 18.9±1.2 Hz to 7.6±1.1 Hz (p < 0.001) upon brushing. Thereafter, the mean firing rates gradually recovered. Conclusions Our results indicate that acute pressure applied to the sciatic nerve exerts a rapid inhibitory effect on the WDR response to both noxious and innocuous stimuli. Our results may partially explain the rapid analgesic effect of acute sciatic nerve pressure noted in clinical studies, and also suggest a new model for the study of pain. PMID:23211003

Melt production in large-scale impact events: Implications and observations at terrestrial craters

NASA Technical Reports Server (NTRS)

Grieve, Richard A. F.; Cintala, Mark J.

1992-01-01

The volume of impact melt relative to the volume of the transient cavity increases with the size of the impact event. Here, we use the impact of chondrite into granite at 15, 25, and 50 km s(sup -1) to model impact-melt volumes at terrestrial craters in crystalline targets and explore the implications for terrestrial craters. Figures are presented that illustrate the relationships between melt volume and final crater diameter D(sub R) for observed terrestrial craters in crystalline targets; also included are model curves for the three different impact velocities. One implication of the increase in melt volumes with increasing crater size is that the depth of melting will also increase. This requires that shock effects occurring at the base of the cavity in simple craters and in the uplifted peaks of central structures at complex craters record progressively higher pressures with increasing crater size, up to a maximum of partial melting (approx. 45 GPa). Higher pressures cannot be recorded in the parautochthonous rocks of the cavity floor as they will be represented by impact melt, which will not remain in place. We have estimated maximum recorded pressures from a review of the literature, using such observations as planar features in quartz and feldspar, diaplectic glasses of feldspar and quartz, and partial fusion and vesiculation, as calibrated with estimates of the pressures required for their formation. Erosion complicates the picture by removing the surficial (most highly shocked) rocks in uplifted structures, thereby reducing the maximum shock pressures observed. In addition, the range of pressures that can be recorded is limited. Nevertheless, the data define a trend to higher recorded pressures with crater diameter, which is consistent with the implications of the model. A second implication is that, as the limit of melting intersects the base of the cavity, central topographic peaks will be modified in appearance and ultimately will not occur. That is, the peak will first develop a central depression, due to the flow of low-strength melted materials, when the melt volume begins to intersect the transient-cavity base.

Process for the manufacture of low density bis-maleimide-carbon microballoon composites

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A. (Inventor); Parker, John A. (Inventor)

1980-01-01

A process for the preparation of composite laminate structures of glass cloth preimpregnated with polybismaleimide resin and adhered to a polybismaleimide-glass or aromatic polyamide paper honeycomb cell structure filled or partially filled with a syntactic foam consisting of a mixture of bismaleimide resin and carbon microballoons. The carbon microballoons are prepared by pyrolyzing phenolic microballoons and subsequently bonded using a 2% bismaleimide solution. The laminate structures are cured for two hours at 477.degree. K. and are adhered to the honeycomb bismaleimide adhesive using a pressure of 700 kN/m.sup.2 pressure at 450.degree. K. The laminate composite is then post-cured for two hours at 527.degree. K. to produce a composite laminate having a density in the range from about 95 kilograms per cubic meter to 130 kilograms per cubic meter.

Slow slip near the trench at the Hikurangi subduction zone, New Zealand.

PubMed

Wallace, Laura M; Webb, Spahr C; Ito, Yoshihiro; Mochizuki, Kimihiro; Hino, Ryota; Henrys, Stuart; Schwartz, Susan Y; Sheehan, Anne F

2016-05-06

The range of fault slip behaviors near the trench at subduction plate boundaries is critical to know, as this is where the world's largest, most damaging tsunamis are generated. Our knowledge of these behaviors has remained largely incomplete, partially due to the challenging nature of crustal deformation measurements at offshore plate boundaries. Here we present detailed seafloor deformation observations made during an offshore slow-slip event (SSE) in September and October 2014, using a network of absolute pressure gauges deployed at the Hikurangi subduction margin offshore New Zealand. These data show the distribution of vertical seafloor deformation during the SSE and reveal direct evidence for SSEs occurring close to the trench (within 2 kilometers of the seafloor), where very low temperatures and pressures exist. Copyright © 2016, American Association for the Advancement of Science.

Vapor pressure and vapor fractionation of silicate melts of tektite composition

USGS Publications Warehouse

Walter, Louis S.; Carron, M.K.

1964-01-01

The total vapor pressure of Philippine tektite melts of approximately 70 per cent silica has been determined at temperatures ranging from 1500 to 2100??C. This pressure is 190 ?? 40 mm Hg at 1500??C, 450 ?? 50 mm at 1800??C and 850 ?? 70 mm at 2100?? C. Determinations were made by visually observing the temperature at which bubbles began to form at a constant low ambient pressure. By varying the ambient pressure, a boiling point curve was constructed. This curve differs from the equilibrium vapor pressure curve due to surface tension effects. This difference was evaluated by determining the equilibrium bubble size in the melt and calculating the pressure due to surface tension, assuming the latter to be 380 dyn/cm. The relative volatility from tektite melts of the oxides of Na, K, Fe, Al and Si has been determined as a function of temperature, total pressure arid roughly, of oxygen fugacity. The volatility of SiO2 is decreased and that of Na2O and K2O is increased in an oxygen-poor environment. Preliminary results indicate that volatilization at 2100??C under atmospheric pressure caused little or no change in the percentage Na2O and K2O. The ratio Fe3 Fe2 of the tektite is increased in ambient air at a pressure of 9 ?? 10-4 mm Hg (= 106.5 atm O2, partial pressure) at 2000??C. This suggests that tektites were formed either at lower oxygen pressures or that they are a product of incomplete oxidation of parent material with a still lower ferricferrous ratio. ?? 1964.

Thermodynamics Behavior of Germanium During Equilibrium Reactions between FeOx-CaO-SiO2-MgO Slag and Molten Copper

NASA Astrophysics Data System (ADS)

Shuva, M. A. H.; Rhamdhani, M. A.; Brooks, G. A.; Masood, S.; Reuter, M. A.

2016-10-01

The distribution ratio of germanium (Ge), L_{{Ge}}^{s/m} during equilibrium reactions between magnesia-saturated FeOx-CaO-SiO2 (FCS) slag and molten copper has been measured under oxygen partial pressures from 10-10 to 10-7 atm and at temperatures 1473 to 1623 K (1200 to 1350 °C). It was observed that the Ge distribution ratio increases with increasing oxygen partial pressure, and with decreasing temperature. It was also observed that the distribution ratio is strongly dependent on slag basicity. The distribution ratio was observed to increase with increasing optical basicity. At fixed CaO concentration in the slag, the distribution ratio was found to increase with increasing Fe/SiO2 ratio, tending to a plateau at L_{{Ge}}^{s/m} = 0.8. This behavior is consistent with the assessment of ionic bond fraction carried out in this study, and suggested the acidic nature of germanium oxide (GeO2) in the slag system studied. The characterisation results of the quenched slag suggested that Ge is present in the FeOx-CaO-SiO2-MgO slag predominantly as GeO2. At 1573 K (1300 °C) and p_{{{{O}}2 }} = 10-8 atm, the activity coefficient of GeO2 in the slag was calculated to be in the range of 0.24 to 1.50. The results from the current study suggested that less-basic slag, high operating temperature, and low oxygen partial pressure promote a low Ge distribution ratio. These conditions are desired for maximizing Ge recovery, for example, during pyrometallurgical processing of Ge-containing e-waste through secondary copper smelting. Overall, the thermodynamics data generated from this study can be used for process modeling purposes for improving recovery of Ge in primary and secondary copper smelting processes.

Influence of defunctionalization and mechanical forces on intestinal epithelial wound healing

PubMed Central

Kovalenko, Pavlo L.; Flanigan, Thomas L.; Chaturvedi, Lakshmi

2012-01-01

The influence on mucosal healing of luminal nutrient flow and the forces it creates are poorly understood. We hypothesized that altered deformation and extracellular pressure mediate, in part, the effects of defunctionalization on mucosal healing. We created patent or partially obstructing defunctionalizing jejunal Roux-en-Y anastomoses in rats to investigate mucosal healing in the absence or presence of luminal nutrient flow and measured luminal pressures to document partial obstruction. We used serosal acetic acid to induce ulcers in the proximal, distal, and defunctionalized intestinal segments. After 3 days, we assessed ulcer area, proliferation, and phosphorylated ERK. In vitro, we measured proliferation and migration in Caco-2 and IEC-6 intestinal epithelial cells subjected to cyclic strain, increased extracellular pressure, or strain and pressure together. Defunctionalization of intestine without obstruction reduced phosphorylated ERK, slowed ulcer healing, and inhibited mucosal proliferation. This outcome was blocked by PD-98059. Partial obstruction delayed ulcer healing but stimulated proliferation independently of ERK. In vitro, strain increased Caco-2 and IEC-6 proliferation and reduced migration across collagen but reduced proliferation and increased migration across fibronectin. In contrast, increased pressure and the combination of pressure and strain increased proliferation and reduced migration independently of substrate. PD-98059 reduced basal migration but increased migration under pressure. These results suggest that loss of the repetitive distension may decrease mucosal healing in defunctionalized bowel, while increased luminal pressure above anastomoses or in spastic bowel disease could further inhibit mucosal healing, despite peristaltic repetitive strain. ERK may mediate the effects of repetitive deformation but not the effects of pressure. PMID:22997197

CO2 solubility and speciation in rhyolitic sediment partial melts at 1.5-3.0 GPa - Implications for carbon flux in subduction zones

NASA Astrophysics Data System (ADS)

Duncan, Megan S.; Dasgupta, Rajdeep

2014-01-01

Partial melts of subducting sediments are thought to be critical agents in carrying trace elements and water to arc basalt source regions. Sediment partial melts may also act as a carrier of CO2. However, the CO2 carrying capacity of natural rhyolitic melts that derive from partial fusion of downgoing sediment at sub-arc depths remains unconstrained. We conducted CO2-solubility experiments on a rhyolitic composition similar to average, low-degree experimental partial melt of pelitic sediments between 1.5 and 3.0 GPa at 1300 °C and containing variable water content. Concentrations of water and carbon dioxide were measured using FTIR. Molecular CO2(CO2mol.) and carbonate anions (CO32-) both appear as equilibrium species in our experimental melts. Estimated total CO2 concentrations (CO2mol.+CO32-) increased with increasing pressure and water content. At 3.0 GPa, the bulk CO2 solubility are in the range of ∼1-2.5 wt.%, for melts with H2O contents between 0.5 and 3.5 wt.%. For melts with low H2O content (∼0.5 wt.%), CO2mol. is the dominant carbon species, while in more H2O-rich melts CO32- becomes dominant. The experimentally determined, speciation-specific CO2 solubilities yielded thermodynamic parameters that control dissolution of CO2 vapor both as CO2mol. and as CO32- in silicate melt for each of our compositions with different water content; CO2vapor ↔CO2melt :lnK0=-15 to -18, ΔV0 = 29 to 14 cm3 mol-1 and CO2vapor +Omelt →CO32-melt :lnK0=-20 to -14, ΔV0 = 9 to 27 cm3 mol-1, with ΔV0 of reaction being larger for formation of CO2mol. in water-poor melts and for formation of CO32- in water-rich melts. Our bulk CO2 solubility data, [CO2] (in wt.%) can be fitted as a function of pressure, P (in GPa) and melt water content, [H2O] (in wt.%) with the following function: [CO2](wt.%)=(-0.01108[H2O]+0.03969)P2+(0.10328[H2O]+0.41165)P. This parameterization suggests that over the range of sub-arc depths of 72-173 km, water-rich sediment partial melt may carry as much as 2.6-5.5 wt.% CO2 to the sub-arc mantle source regions. At saturation, 1.6-3.3 wt.% sediment partial melt relative to the mantle wedge is therefore sufficient to bring up the carbon budget of the mantle wedge to produce primary arc basalts with 0.3 wt.% CO2. Sediment plumes in mantle wedge: Sediment plumes or diapirs may form from the downgoing slab because the sediment layer atop the slab is buoyant relative to the overlying, hanging wall mantle (Currie et al., 2007; Behn et al., 2011). Via this process, sediment layers with carbonates would carry CO2 to the arc source region. Owing to the higher temperature in the mantle wedge, carbonate can breakdown. Behn et al. (2011) suggested that sediment layers as thin as 100 m, appropriate for modern arcs, could form sediment diapirs. They predicted that diapirs would form from the slab in the sub-arc region for most subduction zones today without requiring hydrous melting. H2O-rich fluid driven carbonate breakdown: Hydrous fluid flushing of the slab owing to the breakdown of hydrous minerals could drive carbonate breakdown (Kerrick and Connolly, 2001b; Grove et al., 2002; Gorman et al., 2006). The addition of water would cause decarbonation creating an H2O-CO2-rich fluid that would then flux through the overlying sediment layer, lower the solidus temperature, and trigger melting. Recent geochemical (Cooper et al., 2012) and geodynamic (van Keken, 2003; Syracuse et al., 2010) constraints suggest that the sub-arc slab top temperatures are above the hydrous fluid-present sediment solidus, thus in the presence of excess fluid, both infiltration induced decarbonation and sediment melting may occur. Hot subduction: This is relevant for subduction zones such as Cascadia and Mexico, where slab-surface temperatures are estimated to be higher (Syracuse et al., 2010). A higher temperature could cause carbonate breakdown and sediment partial melting without requiring a hydrous fluid flux. In this case a relatively dry silicate sediment melt will have the opportunity to dissolve and carry CO2. For hot subduction zones, even if sedimentary layer itself does not carry carbonate, CO2 released from basalt-hosted carbonates may be dissolved in sediment partial melt. Experiments conducted on subducted sediment compositions show that the partial melt compositions are generally rhyolitic (Johnson and Plank, 1999; Hermann and Green, 2001; Schmidt et al., 2004; Auzanneau et al., 2006; Hermann and Spandler, 2008; Spandler et al., 2010; Tsuno and Dasgupta, 2011). Therefore, solubility of CO2 in rhyolitic sediment partial melts needs to be known. Previous studies on rhyolitic melts experimentally determined CO2 solubility from 0.05 to 0.66 GPa (Fig. 1; Fogel and Rutherford, 1990; Blank et al., 1993; Tamic et al., 2001). This pressure range is not appropriate for global sub-arc depth range of 72-173 km (Syracuse and Abers, 2006) settings (P = 2-5 GPa). Carbon dioxide solubility experiments at pressures from 1.5 to 3.5 GPa are available but only on simple compositions - i.e., albite, which does not have the chemical complexity of natural sediment partial melts (Fig. 1; Brey, 1976; Mysen, 1976; Mysen et al., 1976; Mysen and Virgo, 1980; Stolper et al., 1987; Brooker et al., 1999). For example, natural rhyolitic melt derived from partial fusion of pelitic sediments contain non-negligible concentrations of Ca2+, Mg2+, Fe2+. Many of these studies were also conducted under mixed-volatile conditions (CO2 + H2O) with H2O contents from 0.06 to 3.3 wt.%. These studies were used in calculating various solubility models: Volatile-Calc (Newman and Lowenstern, 2002), that of Liu et al. (2005), and that of Papale et al. (2006). Volatile-Calc can be used to calculate CO2 solubility only on a generic rhyolite composition up to 0.5 GPa. The model of Liu et al. (2005) is also on a generic rhyolite up to 0.5 GPa, but can calculate mixed volatile concentrations provided the vapor composition is known. The model of Papale et al. (2006) can be used to calculate mixed volatile concentrations for a melt composition of interest, but only up to 1.0 GPa.The literature data show that CO2 solubility increases with increasing pressure and decreases with increasing melt silica content (decreasing NBO/T; e.g., Brooker et al., 2001). The effect of temperature remains somewhat ambiguous, but is thought to be relatively smaller than the pressure or compositional effects, with Mysen (1976) measuring increasing CO2 solubility with temperature for albite melt, Brooker et al. (2001) and Fogel and Rutherford (1990) noticing decreasing CO2 solubility with increasing temperature, and Stolper et al. (1987) concluding that temperature has essentially no effect on total melt CO2 concentration at saturation. The presence of water in the melt also is known to affect CO2 solution (e.g., Mysen, 1976; Eggler and Rosenhauer, 1978), yet quantitative effect of water on CO2 solution in natural rhyolitic melt has only been investigated up to 0.5 GPa (Tamic et al., 2001). In order to determine the CO2 carrying capacity of sediment partial melts, experiments must be conducted at conditions (pressure, temperature, major element compositions, and XH2O) relevant to sub-arc settings.In this study we measured the solubility and speciation of CO2 in rhyolitic sediment partial melts. Experiments were conducted from 1.5 to 3.0 GPa at 1300 °C with variable water contents and synthesized glasses were analyzed for water and carbon speciation using Fourier-transformed infrared spectroscopy. Our measured solubility data allowed us to constrain volume change and equilibrium constant of the CO2 dissolution reactions. Moreover, we parameterize CO2 solubility in sediment partial melt as a function of pressure and melt water content. Our data and empirical model suggest that the CO2 carrying capacity of sediment partial melts is sufficiently high at sub-arc depths and hydrous sediment melt can potentially carry the necessary dose of CO2 to arc mantle source regions.

[Generation of Superoxide Radicals by Complex III in Heart Mitochondria and Antioxidant Effect of Dinitrosyl Iron Complexes at Different Partial Pressure of Oxygen].

PubMed

Dudylina, A L; Ivanova, M V; Shumaev, K B; Ruuge, E K

2016-01-01

The EPR spin-trapping technique and EPR-oximetry were used to study generation of superoxide radicals in heart mitochondria isolated from Wistar rats under conditions of variable oxygen concentration. Lithium phthalocyanine and TEMPONE-15N-D16 were chosen to determine oxygen content in a gas-permeable capillary tube containing mitochondria. TIRON was used as a spin trap. We investigated the influence of different oxygen concentrations in incubation mixture and demonstrated that heart mitochondria can generate superoxide in complex III at different partial pressure of oxygen as well as under the conditions of deep hypoxia (< 5% O2). Dinitrosyl iron complexes with glutathione (the pharmaceutical drug "Oxacom") exerted an antioxidant effect, regardless of the value of the partial pressure of oxygen, but the magnitude and kinetic characteristics of the effect depended on the concentration of the drug.

Method for forming bismuth-based superconducting ceramics

DOEpatents

Maroni, Victor A.; Merchant, Nazarali N.; Parrella, Ronald D.

2005-05-17

A method for reducing the concentration of non-superconducting phases during the heat treatment of Pb doped Ag/Bi-2223 composites having Bi-2223 and Bi-2212 superconducting phases is disclosed. A Pb doped Ag/Bi-2223 composite having Bi-2223 and Bi-2212 superconducting phases is heated in an atmosphere having an oxygen partial pressure not less than about 0.04 atmospheres and the temperature is maintained at the lower of a non-superconducting phase take-off temperature and the Bi-2223 superconducting phase grain growth take-off temperature. The oxygen partial pressure is varied and the temperature is varied between about 815.degree. C. and about 835.degree. C. to produce not less than 80 percent conversion to Pb doped Bi-2223 superconducting phase and not greater than about 20 volume percent non-superconducting phases. The oxygen partial pressure is preferably varied between about 0.04 and about 0.21 atmospheres. A product by the method is disclosed.

Oxygen partial pressure modulates 67-kDa laminin receptor expression, leading to altered activity of the green tea polyphenol, EGCG.

PubMed

Tsukamoto, Shuntaro; Yamashita, Shuya; Kim, Yoon Hee; Kumazoe, Motofumi; Huang, Yuhui; Yamada, Koji; Tachibana, Hirofumi

2012-09-21

(-)-Epigallocatechin-3-O-gallate (EGCG) exhibits anti-tumor activity mediated via the 67-kDa laminin receptor (67LR). In this study, we found that 67LR protein levels are reduced by exposure to low O(2) levels (5%), without affecting the expression of HIF-1α. We also found that EGCG-induced anti-cancer activity is abrogated under low O(2) levels (5%) in various cancer cells. Notably, treatment with the proteasome inhibitor, prevented down-regulation of 67LR and restored sensitivity to EGCG under 5% O(2). In summary, 67LR expression is highly sensitive to O(2) partial pressure, and the activity of EGCG can be regulated in cancer cells by O(2) partial pressure. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

The change of steel surface chemistry regarding oxygen partial pressure and dew point

NASA Astrophysics Data System (ADS)

Norden, Martin; Blumenau, Marc; Wuttke, Thiemo; Peters, Klaus-Josef

2013-04-01

By investigating the surface state of a Ti-IF, TiNb-IF and a MnCr-DP after several series of intercritical annealing, the impact of the annealing gas composition on the selective oxidation process is discussed. On behalf of the presented results, it can be concluded that not the general oxygen partial pressure in the annealing furnace, which is a result of the equilibrium reaction of water and hydrogen, is the main driving force for the selective oxidation process. It is shown that the amounts of adsorbed gases at the strip surface and the effective oxygen partial pressure resulting from the adsorbed gases, which is mainly dependent on the water content of the annealing furnace, is driving the selective oxidation processes occurring during intercritical annealing. Thus it is concluded, that for industrial applications the dew point must be the key parameter value for process control.

Two Phase Flow Modeling: Summary of Flow Regimes and Pressure Drop Correlations in Reduced and Partial Gravity

NASA Technical Reports Server (NTRS)

Balasubramaniam, R.; Rame, E.; Kizito, J.; Kassemi, M.

2006-01-01

The purpose of this report is to provide a summary of state-of-the-art predictions for two-phase flows relevant to Advanced Life Support. We strive to pick out the most used and accepted models for pressure drop and flow regime predictions. The main focus is to identify gaps in predictive capabilities in partial gravity for Lunar and Martian applications. Following a summary of flow regimes and pressure drop correlations for terrestrial and zero gravity, we analyze the fully developed annular gas-liquid flow in a straight cylindrical tube. This flow is amenable to analytical closed form solutions for the flow field and heat transfer. These solutions, valid for partial gravity as well, may be used as baselines and guides to compare experimental measurements. The flow regimes likely to be encountered in the water recovery equipment currently under consideration for space applications are provided in an appendix.

Development of a three-man preprototype CO2 collection subsystem for spacecraft application

NASA Technical Reports Server (NTRS)

Schubert, F. H.; Wynveen, R. A.; Quattrone, P. D.; Marshall, R. D.

1977-01-01

Future long-duration manned space missions will require regenerable carbon dioxide (CO2) collection concepts such as the Electrochemical Depolarized CO2 Concentrator (EDC). A three-man-capacity preprototype CO2 Collection Subsystem (CS-3) is being developed for eventual flight demonstration as part of the Air Revitalization System (ARS) of the Regenerative Life Support Evaluation (RLSE) experiment. The CS-3 employs an EDC to concentrate CO2 from the low partial-pressure levels required of spacecraft atmospheres to high partial-pressure levels needed for oxygen (O2) recovery through CO2 reduction processes. The CS-3 is sized to remove a nominal 3.0 kg/day (6.6 lb/day) of the CO2 to maintain the CO2 partial pressure (pCO2) of the cabin atmosphere at 400 Pa (3 mm Hg) or less. This paper presents the preprototype design, configuration, operation, and projected performance characteristics.

Pathophysiological effect of fat embolism in a canine model of pulmonary contusion.

PubMed

Elmaraghy, A W; Aksenov, S; Byrick, R J; Richards, R R; Schemitsch, E H

1999-08-01

The objective of this study was to determine the individual and combined effects of pulmonary contusion and fat embolism on the hemodynamics and pulmonary pathophysiology in a canine model of acute traumatic pulmonary injury. After a thoracotomy, twenty-one skeletally mature dogs were randomly assigned to one of three groups. Unilateral pulmonary contusion alone was produced in Group 1 (seven dogs); pulmonary contusion and fat embolism, in Group 2 (seven dogs); and fat embolism alone, in Group 3 (seven dogs). Pulmonary contusion was produced by standardized compression of the left lung with a piezoelectric force transducer. Fat embolism was produced by femoral and tibial reaming followed by pressurization of the intramedullary canals. Cardiac output, systolic blood pressure, peak airway pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure, partial pressure of arterial oxygen, and partial pressure of carbon dioxide were monitored for all groups. From these data, several outcome parameters were calculated: total thoracic compliance, alveolar-arterial oxygen gradient, and ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration. All of the dogs were killed after eight hours, and tissue samples were obtained from the brain, kidneys, and lungs for histological analysis. Lung samples were assigned scores for pulmonary edema (the presence of fluid in the alveoli) and inflammation (the presence of neutrophils or hyaline membranes, or both). The percentage of the total area occupied by fat was determined. Pulmonary contusion alone caused a significant increase in the alveolar-arterial oxygen gradient but only after seven hours (p = 0.034). Fat embolism alone caused a significant transient decrease in systolic blood pressure (p = 0.001) and a significant transient increase in pulmonary arterial pressure (p = 0.01) and pulmonary capillary wedge pressure (p = 0.015). Fat embolism alone also caused a significant sustained decrease in the ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration (p = 0.0001) and a significant increase in the alveolar-arterial oxygen gradient (p = 0.0001). The combination of pulmonary contusion and fat embolism caused a significant transient increase in pulmonary capillary wedge pressure (p = 0.0013) as well as a significant sustained decrease in partial pressure of arterial oxygen (p = 0.0001) and a significant decrease in systolic blood pressure (p = 0.001) that lasted for an hour. Pulmonary contusion followed by fat embolism caused a significant increase in peak airway pressure (p = 0.015), alveolar-arterial oxygen gradient (p = 0.0001), and pulmonary arterial pressure (p = 0.01), and these effects persisted for five hours. Total thoracic compliance was decreased 6.4 percent by pulmonary contusion alone, 4.6 percent by fat embolism alone, and 23.5 percent by pulmonary contusion followed by fat embolism. The ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration was decreased 23.7 percent by pulmonary contusion alone, 52.3 percent by fat embolism alone, and 65.8 percent by pulmonary contusion followed by fat embolism. The mean pulmonary edema score was significantly higher with the combined injury than with either injury alone (p = 0.0001). None of the samples from the lungs demonstrated inflammation. Fat embolism combined with pulmonary contusion resulted in a significantly greater mean percentage of the area occupied by fat in the noncontused right lung than in the contused left lung (p = 0.001); however, no significant difference between the right and left lungs could be detected with fat embolism alone. The mean percentage of the glomerular and cerebral areas occupied by fat was greater with fat embolism combined with pulmonary contusion than with fat embolism alone (p = 0.0001 and p = 0.01, respectively). (ABSTRACT TRUNCATED)

Effect of Nitrogen Content on Physical and Chemical Properties of TiN Thin Films Prepared by DC Magnetron Sputtering with Supported Discharge

NASA Astrophysics Data System (ADS)

Kavitha, A.; Kannan, R.; Gunasekhar, K. R.; Rajashabala, S.

2017-10-01

Amorphous titanium nitride (TiN) thin films have been prepared on silicon (Si) and glass substrates by direct-current (DC) reactive magnetron sputtering with a supported discharge (triode). Nitrogen gas (N2) at partial pressure of 0.3 Pa, 0.4 Pa, 0.5 Pa, and 0.6 Pa was used to prepare the TiN thin films, maintaining total pressure of argon and N2 of about 0.7 Pa. The chemical, microstructural, optical, and electrical properties of the TiN thin films were systematically studied. Presence of different phases of Ti with nitrogen (N), oxygen (O2), and carbon (C) elements was revealed by x-ray photoelectron spectroscopy characterization. Increase in the nitrogen pressure from 0.3 Pa to 0.6 Pa reduced the optical bandgap of the TiN thin film from 2.9 eV to 2.7 eV. Photoluminescence study showed that TiN thin film deposited at N2 partial pressure of 0.3 Pa exhibited three shoulder peaks at 330 nm, 335 nm, and 340 nm, which disappeared when the sample was deposited with N2 partial pressure of 0.6 Pa. Increase in the nitrogen content decreased the electrical resistivity of the TiN thin film from 3200 μΩ cm to 1800 μΩ cm. Atomic force microscopy studies of the TiN thin films deposited with N2 partial pressure of 0.6 Pa showed a uniform surface pattern associated with accumulation of fine grains. The results and advantages of this method of preparing TiN thin films are also reported.

Predicting Intracranial Pressure and Brain Tissue Oxygen Crises in Patients With Severe Traumatic Brain Injury.

PubMed

Myers, Risa B; Lazaridis, Christos; Jermaine, Christopher M; Robertson, Claudia S; Rusin, Craig G

2016-09-01

To develop computer algorithms that can recognize physiologic patterns in traumatic brain injury patients that occur in advance of intracranial pressure and partial brain tissue oxygenation crises. The automated early detection of crisis precursors can provide clinicians with time to intervene in order to prevent or mitigate secondary brain injury. A retrospective study was conducted from prospectively collected physiologic data. intracranial pressure, and partial brain tissue oxygenation crisis events were defined as intracranial pressure of greater than or equal to 20 mm Hg lasting at least 15 minutes and partial brain tissue oxygenation value of less than 10 mm Hg for at least 10 minutes, respectively. The physiologic data preceding each crisis event were used to identify precursors associated with crisis onset. Multivariate classification models were applied to recorded data in 30-minute epochs of time to predict crises between 15 and 360 minutes in the future. The neurosurgical unit of Ben Taub Hospital (Houston, TX). Our cohort consisted of 817 subjects with severe traumatic brain injury. Our algorithm can predict the onset of intracranial pressure crises with 30-minute advance warning with an area under the receiver operating characteristic curve of 0.86 using only intracranial pressure measurements and time since last crisis. An analogous algorithm can predict the start of partial brain tissue oxygenation crises with 30-minute advanced warning with an area under the receiver operating characteristic curve of 0.91. Our algorithms provide accurate and timely predictions of intracranial hypertension and tissue hypoxia crises in patients with severe traumatic brain injury. Almost all of the information needed to predict the onset of these events is contained within the signal of interest and the time since last crisis.

[Effect of oxygen tubing connection site on percutaneous oxygen partial pressure and percutaneous carbon dioxide partial pressure in patients with chronic obstructive pulmonary disease during noninvasive positive pressure ventilation].

PubMed

Mi, S; Zhang, L M

2017-04-12

Objective: We evaluated the effects of administering oxygen through nasal catheters inside the mask or through the mask on percutaneous oxygen partial pressure (PcO(2))and percutaneous carbon dioxide partial pressure (PcCO(2)) during noninvasive positive pressure ventilation (NPPV) to find a better way of administering oxygen, which could increase PcO(2) by increasing the inspired oxygen concentration. Methods: Ten healthy volunteers and 9 patients with chronic obstructive pulmonary disease complicated by type Ⅱ respiratory failure were included in this study. Oxygen was administered through a nasal catheter inside the mask or through the mask (oxygen flow was 3 and 5 L/min) during NPPV. PcO(2) and PcCO(2) were measured to evaluate the effects of administering oxygen through a nasal catheter inside the mask or through the mask, indirectly reflecting the effects of administering oxygen through nasal catheter inside the mask or through the mask on inspired oxygen concentration. Results: Compared to administering oxygen through the mask during NPPV, elevated PcO(2) was measured in administering oxygen through the nasal catheter inside the mask, and the differences were statistically significant ( P <0.05). At the same time, there was no significant change in PcCO(2) ( P >0.05). Conclusion: Administering oxygen through a nasal catheter inside the mask during NPPV increased PcO(2) by increasing the inspired oxygen concentration but did not increase PcCO(2). This method of administering oxygen could conserve oxygen and be suitable for family NPPV. Our results also provided theoretical basis for the development of new masks.

Defect formation in LaGa(Mg,Ni)O3-δ : A statistical thermodynamic analysis validated by mixed conductivity and magnetic susceptibility measurements

NASA Astrophysics Data System (ADS)

Naumovich, E. N.; Kharton, V. V.; Yaremchenko, A. A.; Patrakeev, M. V.; Kellerman, D. G.; Logvinovich, D. I.; Kozhevnikov, V. L.

2006-08-01

A statistical thermodynamic approach to analyze defect thermodynamics in strongly nonideal solid solutions was proposed and validated by a case study focused on the oxygen intercalation processes in mixed-conducting LaGa0.65Mg0.15Ni0.20O3-δ perovskite. The oxygen nonstoichiometry of Ni-doped lanthanum gallate, measured by coulometric titration and thermogravimetric analysis at 923-1223K in the oxygen partial pressure range 5×10-5to0.9atm , indicates the coexistence of Ni2+ , Ni3+ , and Ni4+ oxidation states. The formation of tetravalent nickel was also confirmed by the magnetic susceptibility data at 77-600K , and by the analysis of p -type electronic conductivity and Seebeck coefficient as function of the oxygen pressure at 1023-1223K . The oxygen thermodynamics and the partial ionic and hole conductivities are strongly affected by the point-defect interactions, primarily the Coulombic repulsion between oxygen vacancies and/or electron holes and the vacancy association with Mg2+ cations. These factors can be analyzed by introducing the defect interaction energy in the concentration-dependent part of defect chemical potentials expressed by the discrete Fermi-Dirac distribution, and taking into account the probabilities of local configurations calculated via binomial distributions.

Critical hematocrit and oxygen partial pressure in the beating heart of pigs.

PubMed

Hiebl, B; Mrowietz, C; Ploetze, K; Matschke, K; Jung, F

2010-12-01

In cardiac surgery the substitution of lost blood volume by plasma substitutes is a common therapeutical approach. None of the currently available blood substitutes has a sufficient oxygen transport capacity. This can limit the functional integrity of the myocardium known as highly oxygen consumptive. The study was aimed to get information about the minimal hematocrit, also known as critical hematocrit (cHct), which guarantees a stable and adequate oxygen partial pressure in the myocardium (pO2). In adult female pigs (n=7) the hematocrit was reduced by isovolemic blood dilution with an intravenous infusion of isotonic 4% gelatine polysuccinate solution, The substituted blood volume ranged between 3000ml and 7780ml (mean: 5254±1672ml). In all animals the pO2 of the myocardium of the beating heart and of the resting skeletal muscle increased until blood dilution resulted in a Hct decrease down to 15%. Further blood dilution resulted in a decrease of the pO2. Only after the Hct was <10% the pO2 was lower than before blood dilution and accompanied by a lethal ischemia of the myocardium. These data indicate a cHct of about 10% in the pig animal model. Copyright © 2010 Elsevier Inc. All rights reserved.

High Temperature Corrosion of Silicon Carbide and Silicon Nitride in Water Vapor

NASA Technical Reports Server (NTRS)

Opila, E. J.; Robinson, Raymond C.; Cuy, Michael D.; Gray, Hugh R. (Technical Monitor)

2002-01-01

Silicon carbide (SiC) and silicon nitride (Si3N4) are proposed for applications in high temperature combustion environments containing water vapor. Both SiC and Si3N4 react with water vapor to form a silica (SiO2) scale. It is therefore important to understand the durability of SiC, Si3N4 and SiO2 in water vapor. Thermogravimetric analyses, furnace exposures and burner rig results were obtained for these materials in water vapor at temperatures between 1100 and 1450 C and water vapor partial pressures ranging from 0.1 to 3.1 atm. First, the oxidation of SiC and Si3N4 in water vapor is considered. The parabolic kinetic rate law, rate dependence on water vapor partial pressure, and oxidation mechanism are discussed. Second, the volatilization of silica to form Si(OH)4(g) is examined. Mass spectrometric results, the linear kinetic rate law and a volatilization model based on diffusion through a gas boundary layer are discussed. Finally, the combined oxidation and volatilization reactions, which occur when SiC or Si3N4 are exposed in a water vapor-containing environment, are presented. Both experimental evidence and a model for the paralinear kinetic rate law are shown for these simultaneous oxidation and volatilization reactions.

Carbon dioxide exchange of lettuce plants under hypobaric conditions

NASA Technical Reports Server (NTRS)

Corey, K. A.; Bates, M. E.; Adams, S. L.; MacElroy, R. D. (Principal Investigator)

1996-01-01

Growth of plants in a Controlled Ecological Life Support System (CELSS) may involve the use of hypobaric pressures enabling lower mass requirements for atmospheres and possible enhancement of crop productivity. A controlled environment plant growth chamber with hypobaric capability designed and built at Ames Research Center was used to determine if reduced pressures influence the rates of photosynthesis (Ps) and dark respiration (DR) of hydroponically grown lettuce plants. The chamber, referred to as a plant volatiles chamber (PVC), has a growing area of about 0.2 m2, a total gas volume of about 0.7 m3, and a leak rate at 50 kPa of <0.1%/day. When the pressure in the chamber was reduced from ambient to 51 kPa, the rate of net Ps increased by 25% and the rate of DR decreased by 40%. The rate of Ps increased linearly with decreasing pressure. There was a greater effect of reduced pressure at 41 Pa CO2 than at 81 Pa CO2. This is consistent with reports showing greater inhibition of photorespiration (Pr) in reduced O2 at low CO2 concentrations. When the partial pressure of O2 was held constant but the total pressure was varied between 51 and 101 kPa, the rate of CO2 uptake was nearly constant, suggesting that low pressure enhancement of Ps may be mainly attributable to lowered partial pressure of O2 and the accompanying reduction in Pr. The effects of lowered partial pressure of O2 on Ps and DR could result in substantial increases in the rates of biomass production, enabling rapid throughput of crops or allowing flexibility in the use of mass and energy resources for a CELSS.

PH2O and simulated hypobaric hypoxia.

PubMed

Conkin, Johnny

2011-12-01

Some manufacturers of reduced oxygen (O2) breathing devices claim a comparable hypobaric hypoxia (HH) training experience by providing F1O2 < 0.209 at or near sea level pressure to match the ambient oxygen partial pressure (iso-PO2) of the target altitude. I conclude after a review of literature from investigators and manufacturers that these devices may not properly account for the 47 mmHg of water vapor partial pressure that reduces the inspired partial pressure of oxygen (P1O2), which is substantial at higher altitude relative to sea level. Consequently, some devices claiming an equivalent HH experience under normobaric conditions would significantly overestimate the HH condition, especially when simulating altitudes above 10,000 ft (3048 m). At best, the claim should be that the devices provide an approximate HH experience since they only duplicate the ambient PO2 at sea level as at altitude. An approach to reduce the overestimation and standardize the operation is to at least provide machines that create the same P1O2 conditions at sea level as at the target altitude, a simple software upgrade.

Transonic control effectiveness for full and partial span elevon configurations on a 0.0165 scale model space shuttle orbiter tested in the LaRC 8-foot transonic wind tunnel (LA48)

NASA Technical Reports Server (NTRS)

1977-01-01

A transonic pressure tunnel test is reported on an early version of the space shuttle orbiter (designated 089B-139) 0.0165 scale model to systematically determine both longitudinal and lateral control effectiveness associated with various combinations of inboard, outboard, and full span wing trailing edge controls. The test was conducted over a Mach number range from 0.6 to 1.08 at angles of attack from -2 deg to 23 deg at 0 deg sideslip.

Chromium basalts - Experimental determination of redox states and partitioning among synthetic silicate phases

NASA Technical Reports Server (NTRS)

Schreiber, H. D.; Haskin, L. A.

1976-01-01

Experiments were performed on silicate compositions in the forsterite-anorthite-silica and forsterite-anorthite-diopside systems to determine the relative amounts of Cr(II), Cr(III), and Cr(VI) over a wide range of oxygen partial pressures from 10 to the -10th to 1 atm at 1500 and 1550 C. Redox states were measured by visible absorption spectroscopy and electron paramagnetic resonance spectroscopy and titration. It was found that Cr is present almost exclusively as Cr(III) in terrestrial basaltic liquids and as a mixture of Cr(III) and Cr(II) in lunar basaltic liquids.

Method for preparing high transition temperature Nb.sub.3 Ge superconductors

DOEpatents

Newkirk, Lawrence R.; Valencia, Flavio A.

1977-01-01

Bulk coatings of Nb.sub.3 Ge superconductors having transition temperatures in excess of 20 K are readily formed by a chemical vapor deposition technique involving the coreduction of NbCl.sub.5 and GeCl.sub.4 in the presence of hydrogen. The NbCl.sub.5 vapor may advantageously be formed quantitatively in the temperature range of about 250.degree. to 260.degree. C by the chlorination of Nb metal provided the partial pressure of the product NbCl.sub.5 vapor is maintained at or below about 0.1 atm.

Method for preparing high transition temperature Nb/sub 3/Ge superconductors. [Patent application

DOEpatents

Newkirk, L.R.; Valencia, F.A.

1975-06-26

Bulk coatings of Nb/sub 3/Ge superconductors having transition temperatures in excess of 20/sup 0/K are readily formed by a chemical vapor deposition technique involving the coreduction of NbCl/sub 5/ and GeCl/sub 4/ in the presence of hydrogen. The NbCl/sub 5/ vapor may advantageously be formed quantitatively in the temperature range of about 250 to 260/sup 0/C by the chlorination of Nb metal provided the partial pressure of the product NbCl/sub 5/ vapor is maintained at or below about 0.1 atm.

Solubility of mixtures of hydrogen sulfide and carbon dioxide in aqueous N-methyldiethanolamine solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jou, Fang Yuan; Carroll, J.J.; Mather, A.E.

1993-01-01

Aqueous solutions of alkanolamines are commonly used to strip acid gases (H[sub 2]S and CO[sub 2]) from streams contaminated with these components. The two most widely used amines are monoethanolamine (MEA) and diethanolamine (DEA). The solubilities of mixtures of hydrogen sulfide and carbon dioxide in a 35 wt% (3.04 kmol/m[sup 3]) aqueous solution of N-methyldiethanolamine at 40 and 100C have been measured. Partial pressures of the acid gases ranged from 0.006 to 101 kPa at 40C and from 4 to 530 kPa at 100C.

Carbon dioxide sensor. [partial pressure measurement using monochromators

NASA Technical Reports Server (NTRS)

1975-01-01

Analytical techniques for measuring CO2 were evaluated and rated for use with the advanced extravehicular mobility unit. An infrared absorption concept using a dual-wavelength monochromator was selected for investigation. A breadboard carbon dioxide sensor (CDS) was assembled and tested. The CDS performance showed the capability of measuring CO2 over the range of 0 to 4.0 kPa (0 to 30 mmHg) P sub (CO2). The volume and weight of a flight configured CDS should be acceptable. It is recommended that development continue to complete the design of a flight prototype.

Elastic electron differential cross sections for argon atom in the intermediate energy range from 40 eV to 300 eV

NASA Astrophysics Data System (ADS)

Ranković, Miloš Lj.; Maljković, Jelena B.; Tökési, Károly; Marinković, Bratislav P.

2018-02-01

Measurements and calculations for electron elastic differential cross sections (DCS) of argon atom in the energy range from 40 to 300 eV are presented. DCS have been measured in the crossed beam arrangement of the electron spectrometer with an energy resolution of 0.5 eV and angular resolution of 1.5∘ in the range of scattering angles from 20∘ to 126∘. Both angular behaviour and energy dependence of DCS are obtained in a separate sets of experiments, while the absolute scale is achieved via relative flow method, using helium as a reference gas. All data is corrected for the energy transmission function, changes of primary electron beam current and target pressure, and effective path length (volume correction). DCSs are calculated in relativistic framework by expressing the Mott's cross sections in partial wave expansion. Our results are compared with other available data.

The timing of high-temperature retrogression in the Reynolds Range, central Australia: constraints from garnet and epidote Pb-Pb dating

NASA Astrophysics Data System (ADS)

Buick, Ian S.; Frei, Robert; Cartwright, Ian

Lower Calcsilicate Unit metasediments and underlying migmatitic Napperby Gneiss metagranite at Conical Hill in the Reynolds Range, central Australia, underwent regional high-grade ( 680 to 720°C), low-pressure/high-temperature metamorphism at 1594+/- 6Ma. The Lower Calcsilicate Unit is extensively quartz veined and epidotised, and discordant grandite garnet+epidote quartz veins may be traced over tens of metres depth into pegmatites that pooled at the Lower Calcsilicate Unit-Napperby Gneiss contact. The quartz veins were probably precipitated by water-rich fluids that exsolved from partial melts derived from the Napperby Gneiss during cooling from the peak of regional metamorphism to the wet granite solidus. Pb stepwise leaching (PbSL) on garnet from three discordant quartz veins yielded comparable single mineral isochrons of 1566+/-32Ma, 1576+/-3Ma and 1577+/-5Ma, which are interpreted as the age of garnet growth in the veins. These dates are in good agreement with previous Sensitive High Resolution Ion Microprobe (SHRIMP) ages of zircon and monazite formed during high-temperature retrogression (1586+/-5 to 1568+/-4Ma) elsewhere in the Reynolds Range. The relatively small age difference between peak metamorphism and retrograde veining suggests that partial melting and melt crystallisation controlled fluid recycling in the high-grade rocks. However, PbSL experiments on epidote intergrown with, and partially replacing, garnet in two of the veins yielded isochrons of 1454+/-34 and 1469+/- 26Ma. The 100-120Ma age difference between intergrown garnet and late epidote from the same vein suggests that the vein systems may have experienced multiple episodes of fluid flow.

Synthesis, crystal structure, and properties of KSbO{sub 3}-type Bi{sub 3}Mn{sub 1.9}Te{sub 1.1}O{sub 11}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Manrong; Retuerto, Maria; Bok Go, Yong

2013-01-15

Single crystals of Bi{sub 3}Mn{sub 1.9}Te{sub 1.1}O{sub 11} were prepared from NaCl+KCl flux. This compound adopts KSbO{sub 3}-type crystal structure as evidenced by electron and single crystal X-ray diffraction analysis. The three-dimensional channel structure is formed by corner-sharing octahedral (Mn{sub 0.63}Te{sub 0.37}){sub 2}O{sub 10} dimers and two identical (Bi1){sub 4}(Bi2){sub 2} interpenetrating lattices. The intra-dimer Mn/Te-Mn/Te distances in Bi{sub 3}Mn{sub 1.9}Te{sub 1.1}O{sub 11} are short and are consistent with weak metal-metal interactions. The mixed oxidation state of manganese and the edge-sharing octahedral features are confirmed by X-ray near edge absorption spectroscopy measurements, which indicate Bi{sub 3}(Mn{sup III}{sub 1.1}Mn{sup IV}{sub 0.8})Te{supmore » VI}{sub 1.1}O{sub 11} with 57.7% Mn{sup 3+} and 42.3% Mn{sup 4+}. The partial substitution of Te for Mn perturbs long-range magnetic interactions, thereby destroying the ferromagnetic ordering found in Bi{sub 3}Mn{sub 3}O{sub 11} (T{sub C}=150 K). - Graphical abstract: Single crystal of Bi{sub 3}Mn{sub 1.9}Te{sub 1.1}O{sub 11} was grown from NaCl+KCl binary flux, suggesting that the high pressure Bi{sub 3}Mn{sub 3}O{sub 11} phase can be stabilized by partial substitution of Mn by Te at ambient pressure. Bi{sub 3}Mn{sub 1.9}Te{sub 1.1}O{sub 11} adopts a typical three dimensional KSbO{sub 3}-type crystal structure with three interpenetrating lattices and weak intra-dimmer metal-metal interaction caused by the d electrons of Mn. The edge-shared (Mn{sub 0.63}Te{sub 0.37}){sub 2}O{sub 10} octahedral dimer and mixed oxidation state of manganese (Bi{sub 3}(Mn{sup III}{sub 1.1}Mn{sup IV}{sub 0.8})Te{sup VI}{sub 1.1}O{sub 11} with 57.7% Mn{sup 3+} and 42.3% Mn{sup 4+}) features were evidenced by X-ray absorption near edge spectroscopy. Compared with Bi{sub 3}Mn{sub 3}O{sub 11}, the Te substituted Bi{sub 3}Mn{sub 1.9}Te{sub 1.1}O{sub 11} relaxes the crystal structure, but destroys the long-range magnetic ordering and gives short-range magnetic ordering below 5 K. Highlights: Black-Right-Pointing-Pointer High pressure Bi{sub 3}Mn{sub 3}O{sub 11} is stabilized by partial Te substitution at ambient pressure. Black-Right-Pointing-Pointer New KSbO{sub 3}-type Bi{sub 3}Mn{sub 1.9}Te{sub 1.1}O{sub 11} single crystal was grown from binary flux. Black-Right-Pointing-Pointer The presence of mixed oxidation state of manganese is evidenced by XANES study. Black-Right-Pointing-Pointer The Te-substitution destroys the long-range magnetic ordering and relaxes the structure.« less

Measured pressure distributions inside nonaxisymmetric nozzles with partially deployed thrust reversers

NASA Technical Reports Server (NTRS)

Green, Robert S.; Carson, George T., Jr.

1987-01-01

An investigation was conducted in the Langley 16-Foot Transonic Tunnel at static conditions to measure the pressure distributions inside a nonaxisymmetric nozzle with simultaneous partial thrust reversing (50-percent deployment) and thrust vectoring of the primary (forward-thrust) nozzle flow. Geometric forward-thrust-vector angles of 0 and 15 deg. were tested. Test data were obtained at static conditions while nozzle pressure ratio was varied from 2.0 to 4.0. Results indicate that, unlike the 0 deg. vector angle nozzle, a complicated, asymmetric exhaust flow pattern exists in the primary-flow exhaust duct of the 15 deg. vectored nozzle.

Hydrostatic Paradox: Experimental Verification of Pressure Equilibrium

ERIC Educational Resources Information Center

Kodejška, C.; Ganci, S.; Ríha, J.; Sedlácková, H.

2017-01-01

This work is focused on the experimental verification of the balance between the atmospheric pressure acting on the sheet of paper, which encloses the cylinder completely or partially filled with water from below, where the hydrostatic pressure of the water column acts against the atmospheric pressure. First of all this paper solves a theoretical…

40 CFR 86.344-79 - Humidity calculations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... = Molecular weight of air = 28.9645 M H2O = Molecular weight of water = 18.01534 P DB = Saturation vapor pressure of water at the dry bulb temperature (Pa) P DP = saturation vapor pressure of water at the dewpoint temperature (Pa) P v = partial pressure of water vapor (Pa) P WB = saturation vapor pressure of...

40 CFR 86.344-79 - Humidity calculations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... = Molecular weight of air = 28.9645 M H2O = Molecular weight of water = 18.01534 P DB = Saturation vapor pressure of water at the dry bulb temperature (Pa) P DP = saturation vapor pressure of water at the dewpoint temperature (Pa) P v = partial pressure of water vapor (Pa) P WB = saturation vapor pressure of...

Effects of ambient temperature and water vapor on chamber pressure and oxygen level during low atmospheric pressure stunning of poultry.

PubMed

Holloway, Paul H; Pritchard, David G

2017-08-01

The characteristics of the vacuum used in a low atmospheric pressure stunning system to stun (render unconscious) poultry prior to slaughter are described. A vacuum chamber is pumped by a wet screw compressor. The vacuum pressure is reduced from ambient atmospheric pressure to an absolute vacuum pressure of ∼250 Torr (∼33 kPa) in ∼67 sec with the vacuum gate valve fully open. At ∼250 Torr, the sliding gate valve is partially closed to reduce effective pumping speed, resulting in a slower rate of decreasing pressure. Ambient temperature affects air density and water vapor pressure and thereby oxygen levels and the time at the minimum total pressure of ∼160 Torr (∼21 kPa) is varied from ∼120 to ∼220 sec to ensure an effective stun within the 280 seconds of each cycle. The reduction in total pressure results in a gradual reduction of oxygen partial pressure that was measured by a solid-state electrochemical oxygen sensor. The reduced oxygen pressure leads to hypoxia, which is recognized as a humane method of stunning poultry. The system maintains an oxygen concentration of <5% for at least 2 minutes, which ensures that birds are irreversibly stunned. Calculated pump down (pressure versus time) data match experimental data very closely because the programmable logic controller and the human machine interface enable precise and accurate control. The vacuum system operates in the turbulent viscous flow regime, and is best characterized by absolute vacuum pressure rather than gauge pressure. Neither the presence of broiler chickens nor different fore-line pipe designs of four parallel commercial systems affected the pressure-time data. Water in wet air always reduces the oxygen concentrations to a value lower than in dry air. The partial pressure of water and oxygen were found to depend on the pump down parameters due to the formation of fog in the chamber and desorption of water from the birds and the walls of the vacuum chamber. © The Author 2017. Published by Oxford University Press on behalf of Poultry Science Association.

Effects of ambient temperature and water vapor on chamber pressure and oxygen level during low atmospheric pressure stunning of poultry

PubMed Central

Holloway, Paul H.; Pritchard, David G.

2017-01-01

Abstract The characteristics of the vacuum used in a low atmospheric pressure stunning system to stun (render unconscious) poultry prior to slaughter are described. A vacuum chamber is pumped by a wet screw compressor. The vacuum pressure is reduced from ambient atmospheric pressure to an absolute vacuum pressure of ∼250 Torr (∼33 kPa) in ∼67 sec with the vacuum gate valve fully open. At ∼250 Torr, the sliding gate valve is partially closed to reduce effective pumping speed, resulting in a slower rate of decreasing pressure. Ambient temperature affects air density and water vapor pressure and thereby oxygen levels and the time at the minimum total pressure of ∼160 Torr (∼21 kPa) is varied from ∼120 to ∼220 sec to ensure an effective stun within the 280 seconds of each cycle. The reduction in total pressure results in a gradual reduction of oxygen partial pressure that was measured by a solid-state electrochemical oxygen sensor. The reduced oxygen pressure leads to hypoxia, which is recognized as a humane method of stunning poultry. The system maintains an oxygen concentration of <5% for at least 2 minutes, which ensures that birds are irreversibly stunned. Calculated pump down (pressure versus time) data match experimental data very closely because the programmable logic controller and the human machine interface enable precise and accurate control. The vacuum system operates in the turbulent viscous flow regime, and is best characterized by absolute vacuum pressure rather than gauge pressure. Neither the presence of broiler chickens nor different fore-line pipe designs of four parallel commercial systems affected the pressure-time data. Water in wet air always reduces the oxygen concentrations to a value lower than in dry air. The partial pressure of water and oxygen were found to depend on the pump down parameters due to the formation of fog in the chamber and desorption of water from the birds and the walls of the vacuum chamber. PMID:28521045

Cullin 5 Expression in the Rat: Cellular and Tissue Distribution, and Changes in Response to Water Deprivation and Hemorrhagic Shock

DTIC Science & Technology

2003-02-28

of Health p53 tumor suppressor PBS phosphate buffered saline PCO2 partial pressure of carbon dioxide PO2 partial pressure of oxygen PCR...buffered saline TTBS tween-20 tris buffered saline TonEBP tonicity-response enhancer binding protein TSNRP TriService Nursing Research Program...growth and metabolism (Hochstrasser, 1995; Deshaies, 1999). Although traditionally seen as no more than a means of eliminating no longer needed

A partial pressure monitor and controller for stable ozone flow from a silica gel trap

NASA Astrophysics Data System (ADS)

Stevens, R. E.; Hsiao, C.-W.; Le, Linh; Curro, N. J.; Monton, B. J.; Chang, B.-Y.; Kung, C.-Y.; Kittrell, C.; Kinsey, J. L.

1998-06-01

A new ozone trapping system designed for safe and consistent delivery to a reaction vessel is described. Silica gel is used to trap the ozone because of its known safety advantages over traps that store ozone in liquid form. The new design is free of any liquid baths, such as freon or flammable solvents. A circuit design for monitoring and controlling the ozone partial pressure of 6-25 Torr is also described.

A new approach to non-invasive oxygenated mixed venous PCO(sub)2

NASA Technical Reports Server (NTRS)

Fisher, Joseph A.; Ansel, Clifford A.

1986-01-01

A clinically practical technique was developed to calculate mixed venous CO2 partial pressure for the calculation of cardiac output by the Fick technique. The Fick principle states that the cardiac output is equal to the CO2 production divided by the arterio-venous CO2 content difference of the pulmonary vessels. A review of the principles involved in the various techniques used to estimate venous CO2 partial pressure is presented.

Mechanical Integrity of Flexible In-Zn-Sn-O Film for Flexible Transparent Electrode

NASA Astrophysics Data System (ADS)

Kim, Young Sung; Oh, Se-In; Choa, Sung-Hoon

2013-05-01

The mechanical integrity of transparent In-Zn-Sn-O (IZTO) films is investigated using outer/inner bending, stretching, and twisting tests. Amorphous IZTO films are grown using a pulsed DC magnetron sputtering system with an IZTO target on a polyimide substrate at room temperature. Changes in the optical and electrical properties of IZTO films depend on the oxygen partial pressure applied during the film deposition process. In the case of 3% oxygen partial pressure, the IZTO films exhibit s resistivity of 8.3×10-4 Ω cm and an optical transmittance of 86%. The outer bending test shows that the critical bending radius decreases from 10 to 7.5 mm when the oxygen partial pressure is increased from 1 to 3%. The inner bending test reveals that the critical bending radius of all IZTO films is 3.5 mm regardless of oxygen partial pressure. The IZTO films also show excellent mechanical reliability in the bending fatigue tests of more than 10,000 cycles. In the uniaxial stretching tests, the electrical resistance of the IZTO film does not change until a strain of 2.4% is reached. The twisting tests demonstrate that the electrical resistance of IZTO films remains unchanged up to 25°. These results suggest that IZTO films have excellent mechanical durability and flexibility in comparison with already reported crystallized indium tin oxide (ITO) films.

Oxygen availability and spreading depolarizations provide complementary prognostic information in neuromonitoring of aneurysmal subarachnoid hemorrhage patients.

PubMed

Winkler, Maren Kl; Dengler, Nora; Hecht, Nils; Hartings, Jed A; Kang, Eun J; Major, Sebastian; Martus, Peter; Vajkoczy, Peter; Woitzik, Johannes; Dreier, Jens P

2017-05-01

Multimodal neuromonitoring in neurocritical care increasingly includes electrocorticography to measure epileptic events and spreading depolarizations. Spreading depolarization causes spreading depression of activity (=isoelectricity) in electrically active tissue. If the depression is long-lasting, further spreading depolarizations occur in still isoelectric tissue where no activity can be suppressed. Such spreading depolarizations are termed isoelectric and are assumed to indicate energy compromise. However, experimental and clinical recordings suggest that long-lasting spreading depolarization-induced depression and isoelectric spreading depolarizations are often recorded outside of the actual ischemic zones, allowing the remote diagnosis of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage. Here, we analyzed simultaneous electrocorticography and tissue partial pressure of oxygen recording in 33 aneurysmal subarachnoid hemorrhage patients. Multiple regression showed that both peak total depression duration per recording day and mean baseline tissue partial pressure of oxygen were independent predictors of outcome. Moreover, tissue partial pressure of oxygen preceding spreading depolarization was similar and differences in tissue partial pressure of oxygen responses to spreading depolarization were only subtle between isoelectric spreading depolarizations and spreading depressions. This further supports that, similar to clustering of spreading depolarizations, long spreading depolarization-induced periods of isoelectricity are useful to detect energy compromise remotely, which is valuable because the exact location of future developing pathology is unknown at the time when the neurosurgeon implants recording devices.

Derivation of intermediate to silicic magma from the basalt analyzed at the Vega 2 landing site, Venus.

PubMed

Shellnutt, J Gregory

2018-01-01

Geochemical modeling using the basalt composition analyzed at the Vega 2 landing site indicates that intermediate to silicic liquids can be generated by fractional crystallization and equilibrium partial melting. Fractional crystallization modeling using variable pressures (0.01 GPa to 0.5 GPa) and relative oxidation states (FMQ 0 and FMQ -1) of either a wet (H2O = 0.5 wt%) or dry (H2O = 0 wt%) parental magma can yield silicic (SiO2 > 60 wt%) compositions that are similar to terrestrial ferroan rhyolite. Hydrous (H2O = 0.5 wt%) partial melting can yield intermediate (trachyandesite to andesite) to silicic (trachydacite) compositions at all pressures but requires relatively high temperatures (≥ 950°C) to generate the initial melt at intermediate to low pressure whereas at high pressure (0.5 GPa) the first melts will be generated at much lower temperatures (< 800°C). Anhydrous partial melt modeling yielded mafic (basaltic andesite) and alkaline compositions (trachybasalt) but the temperature required to produce the first liquid is very high (≥ 1130°C). Consequently, anhydrous partial melting is an unlikely process to generate derivative liquids. The modeling results indicate that, under certain conditions, the Vega 2 composition can generate silicic liquids that produce granitic and rhyolitic rocks. The implication is that silicic igneous rocks may form a small but important component of the northeast Aphrodite Terra.

Derivation of intermediate to silicic magma from the basalt analyzed at the Vega 2 landing site, Venus

PubMed Central

2018-01-01

Geochemical modeling using the basalt composition analyzed at the Vega 2 landing site indicates that intermediate to silicic liquids can be generated by fractional crystallization and equilibrium partial melting. Fractional crystallization modeling using variable pressures (0.01 GPa to 0.5 GPa) and relative oxidation states (FMQ 0 and FMQ -1) of either a wet (H2O = 0.5 wt%) or dry (H2O = 0 wt%) parental magma can yield silicic (SiO2 > 60 wt%) compositions that are similar to terrestrial ferroan rhyolite. Hydrous (H2O = 0.5 wt%) partial melting can yield intermediate (trachyandesite to andesite) to silicic (trachydacite) compositions at all pressures but requires relatively high temperatures (≥ 950°C) to generate the initial melt at intermediate to low pressure whereas at high pressure (0.5 GPa) the first melts will be generated at much lower temperatures (< 800°C). Anhydrous partial melt modeling yielded mafic (basaltic andesite) and alkaline compositions (trachybasalt) but the temperature required to produce the first liquid is very high (≥ 1130°C). Consequently, anhydrous partial melting is an unlikely process to generate derivative liquids. The modeling results indicate that, under certain conditions, the Vega 2 composition can generate silicic liquids that produce granitic and rhyolitic rocks. The implication is that silicic igneous rocks may form a small but important component of the northeast Aphrodite Terra. PMID:29584745

SSMILES.

ERIC Educational Resources Information Center

Sunal, Dennis W., Ed.; Tracy, Dyanne M., Ed.

1993-01-01

Describes an activity in which the students utilize the mathematics concepts of ratio, proportion, and data tabulation to examine the relationship between air pressure, temperature, and humidity. Students learn to approximate partial pressure by using humidity and temperature readings and by interpolating from the vapor pressure-temperature table.…

Method to Estimate the Dissolved Air Content in Hydraulic Fluid

NASA Technical Reports Server (NTRS)

Hauser, Daniel M.

2011-01-01

In order to verify the air content in hydraulic fluid, an instrument was needed to measure the dissolved air content before the fluid was loaded into the system. The instrument also needed to measure the dissolved air content in situ and in real time during the de-aeration process. The current methods used to measure the dissolved air content require the fluid to be drawn from the hydraulic system, and additional offline laboratory processing time is involved. During laboratory processing, there is a potential for contamination to occur, especially when subsaturated fluid is to be analyzed. A new method measures the amount of dissolved air in hydraulic fluid through the use of a dissolved oxygen meter. The device measures the dissolved air content through an in situ, real-time process that requires no additional offline laboratory processing time. The method utilizes an instrument that measures the partial pressure of oxygen in the hydraulic fluid. By using a standardized calculation procedure that relates the oxygen partial pressure to the volume of dissolved air in solution, the dissolved air content is estimated. The technique employs luminescent quenching technology to determine the partial pressure of oxygen in the hydraulic fluid. An estimated Henry s law coefficient for oxygen and nitrogen in hydraulic fluid is calculated using a standard method to estimate the solubility of gases in lubricants. The amount of dissolved oxygen in the hydraulic fluid is estimated using the Henry s solubility coefficient and the measured partial pressure of oxygen in solution. The amount of dissolved nitrogen that is in solution is estimated by assuming that the ratio of dissolved nitrogen to dissolved oxygen is equal to the ratio of the gas solubility of nitrogen to oxygen at atmospheric pressure and temperature. The technique was performed at atmospheric pressure and room temperature. The technique could be theoretically carried out at higher pressures and elevated temperatures.

Contributions of aortic pulse wave velocity and backward wave pressure to variations in left ventricular mass are independent of each other.

PubMed

Bello, Hamza; Norton, Gavin R; Ballim, Imraan; Libhaber, Carlos D; Sareli, Pinhas; Woodiwiss, Angela J

2017-05-01

Aortic pulse wave velocity (PWV) and backward waves, as determined from wave separation analysis, predict cardiovascular events beyond brachial blood pressure. However, the extent to which these aortic hemodynamic variables contribute independent of each other is uncertain. In 749 randomly selected participants of African ancestry, we therefore assessed the extent to which relationships between aortic PWV or backward wave pressures (Pb) (and hence central aortic pulse pressure [PPc]) and left ventricular mass index (LVMI) occur independent of each other. Aortic PWV, PPc, forward wave pressure (Pf), and Pb were determined using radial applanation tonometry and SphygmoCor software and LVMI using echocardiography; 44.5% of participants had an increased left ventricular mass indexed to height 1.7 . With adjustments for age, brachial systolic blood pressure or PP, and additional confounders, PPc and Pb, but not Pf, were independently related to LVMI and left ventricular hypertrophy (LVH) in both men and women. However, PWV was independently associated with LVMI in women (partial r = 0.16, P < .001), but not in men (partial r = 0.03), and PWV was independently associated with LVH in women (P < .05), but not in men (P = .07). With PWV and Pb included in the same multivariate regression models, PWV (partial r = 0.14, P < .005) and Pb (partial r = 0.10, P < .05) contributed to a similar extent to variations in LVMI in women. In addition, with PWV and Pb included in the same multivariate regression models, PWV (P < .05) and Pb (P < .02) contributed to LVH in women. In conclusion, aortic PWV and Pb (and hence pulse pressure) although both associated with LVMI and LVH produce effects which are independent of each other. Copyright © 2017 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

Scaling of Two-Phase Flows to Partial-Earth Gravity

NASA Technical Reports Server (NTRS)

Hurlbert, Kathryn M.; Witte, Larry C.

2003-01-01

A report presents a method of scaling, to partial-Earth gravity, of parameters that describe pressure drops and other characteristics of two-phase (liquid/ vapor) flows. The development of the method was prompted by the need for a means of designing two-phase flow systems to operate on the Moon and on Mars, using fluid-properties and flow data from terrestrial two-phase-flow experiments, thus eliminating the need for partial-gravity testing. The report presents an explicit procedure for designing an Earth-based test bed that can provide hydrodynamic similarity with two-phase fluids flowing in partial-gravity systems. The procedure does not require prior knowledge of the flow regime (i.e., the spatial orientation of the phases). The method also provides for determination of pressure drops in two-phase partial-gravity flows by use of a generalization of the classical Moody chart (previously applicable to single-phase flow only). The report presents experimental data from Mars- and Moon-activity experiments that appear to demonstrate the validity of this method.

A Theoretical Study of Methanol Oxidation on RuO 2(110): Bridging the Pressure Gap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Latimer, Allegra A.; Abild-Pedersen, Frank; Norskov, Jens K.

Partial oxidation catalysis is often fraught with selectivity problems, largely because there is a tendency of oxidation products to be more reactive than the starting material. One industrial process that has successfully overcome this problem is partial oxidation of methanol to formaldehyde. This process has become a global success, with an annual production of 30 million tons. Although ruthenium catalysts have not shown activity as high as the current molybdena or silver-based industrial standards, the study of ruthenium systems has the potential to elucidate which catalyst properties facilitate the desired partial oxidation reaction as opposed to deep combustion due tomore » a pressure-dependent selectivity “switch” that has been observed in ruthenium-based catalysts. In this work, we find that we are able to successfully rationalize this “pressure gap” using near-ab initio steady-state microkinetic modeling on RuO 2(110). We obtain molecular desorption prefactors from experiment and determine all other energetics using density functional theory. We show that, under ambient pressure conditions, formaldehyde production is favored on RuO 2(110), whereas under ultrahigh vacuum pressure conditions, full combustion to CO 2 takes place. We glean from our model several insights regarding how coverage effects, oxygen activity, and rate-determining steps influence selectivity and activity. As a result, we believe the understanding gained in this work might advise and inspire the greater partial oxidation community and be applied to other catalytic processes which have not yet found industrial success.« less

A Theoretical Study of Methanol Oxidation on RuO 2(110): Bridging the Pressure Gap

DOE PAGES

Latimer, Allegra A.; Abild-Pedersen, Frank; Norskov, Jens K.

2017-05-26

Partial oxidation catalysis is often fraught with selectivity problems, largely because there is a tendency of oxidation products to be more reactive than the starting material. One industrial process that has successfully overcome this problem is partial oxidation of methanol to formaldehyde. This process has become a global success, with an annual production of 30 million tons. Although ruthenium catalysts have not shown activity as high as the current molybdena or silver-based industrial standards, the study of ruthenium systems has the potential to elucidate which catalyst properties facilitate the desired partial oxidation reaction as opposed to deep combustion due tomore » a pressure-dependent selectivity “switch” that has been observed in ruthenium-based catalysts. In this work, we find that we are able to successfully rationalize this “pressure gap” using near-ab initio steady-state microkinetic modeling on RuO 2(110). We obtain molecular desorption prefactors from experiment and determine all other energetics using density functional theory. We show that, under ambient pressure conditions, formaldehyde production is favored on RuO 2(110), whereas under ultrahigh vacuum pressure conditions, full combustion to CO 2 takes place. We glean from our model several insights regarding how coverage effects, oxygen activity, and rate-determining steps influence selectivity and activity. As a result, we believe the understanding gained in this work might advise and inspire the greater partial oxidation community and be applied to other catalytic processes which have not yet found industrial success.« less

Evaluation of anticipatory signal to steam generator pressure control program for 700 MWe Indian pressurized heavy water reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pahari, S.; Hajela, S.; Rammohan, H. P.

2012-07-01

700 MWe Indian Pressurized Heavy Water Reactor (IPHWR) is horizontal channel type reactor with partial boiling at channel outlet. Due to boiling, it has a large volume of vapor present in the primary loops. It has two primary loops connected with the help of pressurizer surge line. The pressurizer has a large capacity and is partly filled by liquid and partly by vapor. Large vapor volume improves compressibility of the system. During turbine trip or load rejection, pressure builds up in Steam Generator (SG). This leads to pressurization of Primary Heat Transport System (PHTS). To control pressurization of SG andmore » PHTS, around 70% of the steam generated in SG is dumped into the condenser by opening Condenser Steam Dump Valves (CSDVs) and rest of the steam is released to the atmosphere by opening Atmospheric Steam Discharge Valves (ASDVs) immediately after sensing the event. This is accomplished by adding anticipatory signal to the output of SG pressure controller. Anticipatory signal is proportional to the thermal power of reactor and the proportionality constant is set so that SG pressure controller's output jacks up to ASDV opening range when operating at 100% FP. To simulate this behavior for 700 MWe IPHWR, Primary and secondary heat transport system is modeled. SG pressure control and other process control program have also been modeled to capture overall plant dynamics. Analysis has been carried out with 3-D neutron kinetics coupled thermal hydraulic computer code ATMIKA.T to evaluate the effect of the anticipatory signal on PHT pressure and over all plant dynamics during turbine trip in 700 MWe IPHWR. This paper brings out the results of the analysis with and without considering anticipatory signal in SG pressure control program during turbine trip. (authors)« less

Double and multiple contacts of similar elastic materials

NASA Astrophysics Data System (ADS)

Sundaram, Narayan K.

Ongoing fretting fatigue research has focussed on developing robust contact mechanics solutions for complicated load histories involving normal, shear, moment and bulk loads. For certain indenter profiles and applied loads, the contact patch separates into two disconnected regions. Existing Singular Integral Equation (SIE) techniques do not address these situations. A fast numerical tool is developed to solve such problems for similar elastic materials for a wide range of profiles and load paths including applied moments and remote bulk-stress effects. This tool is then used to investigate two problems in double contacts. The first, to determine the shear configuration space for a biquadratic punch for the generalized Cattaneo-Mindlin problem. The second, to obtain quantitative estimates of the interaction between neighboring cylindrical contacts for both the applied normal load and partial slip problems up to the limits of validity of the halfspace assumption. In double contact problems without symmetry, obtaining a unique solution requires the satisfaction of a condition relating the contact ends, rigid-body rotation and profile function. This condition has the interpretation that a rigid-rod connecting the inner contact ends of an equivalent frictionless double contact of a rigid indenter and halfspace may only undergo rigid body motions. It is also found that the ends of stick-zones, local slips and remote-applied strains in double contact problems are related by an equation expressing tangential surface-displacement continuity. This equation is essential to solve partial-slip problems without contact equivalents. Even when neighboring cylindrical contacts may be treated as non-interacting for the purpose of determining the pressure tractions, this is not generally true if a shear load is applied. The mutual influence of neighboring contacts in partial slip problems is largest at small shear load fractions. For both the pressure and partial slip problems, the interactions are stronger with increasing strength of loading and contact proximity. A new contact algorithm is developed and the SIE method extended to tackle contact problems with an arbitrary number of contact patches with no approximations made about contact interactions. In the case of multiple contact problems determining the correct contact configuration is significantly more complicated than in double contacts, necessitating a new approach. Both the normal contact and partial slip problems are solved. The tool is then used to study contacts of regular rough cylinders, a flat with rounded punch with superimposed sinusoidal roughness and is also applied to analyze the contact of an experimental rough surface with a halfspace. The partial slip results for multiple-contacts are generally consistent with Cattaneo-Mindlin continuum scale results, in that the outermost contacts tend to be in full sliding. Lastly, the influence of plasticity on frictionless multiple contact problems is studied using FEM for two common steel and aluminum alloys. The key findings are that the plasticity decreases the peak pressure and increases both real and apparent contact areas, thus 'blunting' the sharp pressures caused by the contact asperities in pure elasticity. Further, it is found that contact plasticity effects and load for onset of first yield are strongly dependent on roughness amplitude, with higher plasticity effects and lower yield-onset load at higher roughness amplitudes.

Flight test evaluation of an RAF high altitude partial pressure protective assembly

NASA Technical Reports Server (NTRS)

Ashworth, G. R.; Putnam, T. W.; Dana, W. J.; Enevoldson, E. K.; Winter, W. R.

1979-01-01

A partial pressure suit was evaluated during tests in an F-104 and F-15 as a protective garment for emergency descents. The garment is an pressure jerkin and modified anti-g suit combined with an oronasal mask. The garment can be donned and doffed at the aircraft to minimize thermal buildup. The oronasal mask was favored by the pilots due to its immobility on the face during high g-loading. The garment was chosen to provide optimum dexterity for the pilot, which is not available in a full pressure suit, while protecting the pilot at altitudes up to 18,288 meters, during a cabin decompression, and subsequent aircraft descent. During cabin decompressions in the F-104 and F-15, cabin pressure altitude was measured at various aircraft angles of attack, Mach numbers, and altitudes to determine the effect of the aerodynamic slipstream on the cabin altitude.

Diaphragm electrical activity during negative lower torso pressure in quadriplegic men.

PubMed

Banzett, R B; Inbar, G F; Brown, R; Goldman, M; Rossier, A; Mead, J

1981-09-01

We recorded the diaphragm electromyogram (EMG) of quadriplegic men before and during exposure of the lower torso to continuous negative pressure, which caused shortening of the inspiratory muscles by expanding the respiratory system by one tidal volume. The moving-time-averaged diaphragm EMG was larger during expansion of the respiratory system. When we repeated the experiment with subjects who breathed through a mouthpiece, we found qualitatively similar EMG changes and little or no change in tidal volume or end-tidal CO2 partial pressure. When the pressure was applied or removed rapidly, changes in EMG occurred within one or two breaths. Because end-tidal CO2 partial pressure did not increase, and because the response was rapid, we suggest that the response results from proprioceptive, rather than chemoreceptive, reflexes. As most of these men had complete spinal lesions at C6 or C7 the afferent pathways are likely to be vagal or phrenic.

Study of the velocity distribution influence upon the pressure pulsations in draft tube model of hydro-turbine

NASA Astrophysics Data System (ADS)

Sonin, V.; Ustimenko, A.; Kuibin, P.; Litvinov, I.; Shtork, S.

2016-11-01

One of the mechanisms of generation of powerful pressure pulsations in the circuit of the turbine is a precessing vortex core, formed behind the runner at the operation points with partial or forced loads, when the flow has significant residual swirl. To study periodic pressure pulsations behind the runner the authors of this paper use approaches of experimental modeling and methods of computational fluid dynamics. The influence of velocity distributions at the output of the hydro turbine runner on pressure pulsations was studied based on analysis of the existing and possible velocity distributions in hydraulic turbines and selection of the distribution in the extended range. Preliminary numerical calculations have showed that the velocity distribution can be modeled without reproduction of the entire geometry of the circuit, using a combination of two blade cascades of the rotor and stator. Experimental verification of numerical results was carried out in an air bench, using the method of 3D-printing for fabrication of the blade cascades and the geometry of the draft tube of hydraulic turbine. Measurements of the velocity field at the input to a draft tube cone and registration of pressure pulsations due to precessing vortex core have allowed building correlations between the velocity distribution character and the amplitude-frequency characteristics of the pulsations.

Long-term outcome of using posterior-thigh fasciocutaneous flaps for the treatment of ischial pressure sores.

PubMed

Lin, Haodong; Hou, Chunlin; Chen, Aimin; Xu, Zhen

2010-08-01

Among the many difficult problems presented by patients with spinal cord injuries, management of ischial pressure ulcers remains challenging for reconstructive surgeons. This study describes the long-term outcome of using posterior-thigh fasciocutaneous flaps for the treatment of ischial pressure sores. Between January 1999 and June 2003, 12 patients with ischial sores were enrolled in this study. All the patients underwent early aggressive surgical debridement followed by surgical reconstruction with a laterally based posterior-thigh fasciocutaneous flap. The follow-up period ranged from 24 months to 97 months (mean, 62 months). All the flaps survived, and there were no partial flap losses. Primary-wound healing occurred in all the cases. In two patients, Grade II ischial pressure sores recurred 24 months and 27 months after the operation. There was no recurrence in the other 10 patients. The posterior-thigh fasciocutaneous pedicled flap was a good method for treating ischial bed sores. This flap could be used to treat recurrences observed after primary bed-sore treatment with other methods. The flap was easy to raise, and it did not cause any donor-site morbidity. The long-term outcome of using posterior-thigh fasciocutaneous flaps for the treatment of ischial pressure sores was generally good. (c) Thieme Medical Publishers.

Transition Within Leeward Plane of Axisymmetric Bodies at Incidence in Supersonic Flow

NASA Technical Reports Server (NTRS)

Tokugawa, Naoko; Choudhari, Meelan; Ishikawa, Hiroaki; Ueda, Yoshine; Fujii, Keisuke; Atobe, Takashi; Li, Fei; Chang, Chau-Lyan; White, Jeffery

2012-01-01

Boundary layer transition along the leeward symmetry plane of axisymmetric bodies at nonzero angle of attack in supersonic flow was investigated experimentally and numerically as part of joint research between the Japan Aerospace Exploration Agency (JAXA) and National Aeronautics and Space Administration (NASA). Transition over four axisymmetric bodies (namely, Sears-Haack body, semi-Sears-Haack body, straight cone and flared cone) with different axial pressure gradients was measured in two different facilities with different unit Reynolds numbers. The semi-Sears-Haack body and flared cone were designed at JAXA to broaden the range of axial pressure distributions. For a body shape with an adverse pressure gradient (i.e., flared cone), the experimentally measured transition patterns show an earlier transition location along the leeward symmetry plane in comparison with the neighboring azimuthal locations. For nearly zero pressure gradient (i.e.,straight cone), this feature is only observed at the larger unit Reynolds number. Later transition along the leeward plane was observed for the remaining two body shapes with a favorable pressure gradient. The observed transition patterns are only partially consistent with the numerical predictions based on linear stability analysis. Additional measurements are used in conjunction with the stability computations to explore the phenomenon of leeward line transition and the underlying transition mechanism in further detail.

Glaucoma (image)

MedlinePlus

Glaucoma is a condition of increased fluid pressure inside the eye. The increased pressure causes compression of ... nerve which can eventually lead to nerve damage. Glaucoma can cause partial vision loss, with blindness as ...

The Finite-Surface Method for incompressible flow: a step beyond staggered grid

NASA Astrophysics Data System (ADS)

Hokpunna, Arpiruk; Misaka, Takashi; Obayashi, Shigeru

2017-11-01

We present a newly developed higher-order finite surface method for the incompressible Navier-Stokes equations (NSE). This method defines the velocities as a surface-averaged value on the surfaces of the pressure cells. Consequently, the mass conservation on the pressure cells becomes an exact equation. The only things left to approximate is the momentum equation and the pressure at the new time step. At certain conditions, the exact mass conservation enables the explicit n-th order accurate NSE solver to be used with the pressure treatment that is two or four order less accurate without loosing the apparent convergence rate. This feature was not possible with finite volume of finite difference methods. We use Fourier analysis with a model spectrum to determine the condition and found that the range covers standard boundary layer flows. The formal convergence and the performance of the proposed scheme is compared with a sixth-order finite volume method. Finally, the accuracy and performance of the method is evaluated in turbulent channel flows. This work is partially funded by a research colloaboration from IFS, Tohoku university and ASEAN+3 funding scheme from CMUIC, Chiang Mai University.

The effect of processing on the mechanical properties of self-reinforced composites

NASA Astrophysics Data System (ADS)

Hassani, Farzaneh; Martin, Peter J.; Falzon, Brian G.

2018-05-01

Hot-compaction is one of the most common manufacturing methods for creating recyclable all thermoplastic composites. The current work investigates the compaction of highly oriented self-reinforced fabrics with three processing methods to study the effect of pressure and temperature in the tensile mechanical properties of the consolidated laminates. Hot-press, calender roller and vacuum bag technique were adopted to consolidate bi-component polypropylene woven fabrics in a range of pressures and compaction temperatures. Hot-pressed samples exhibited the highest quality of compaction. The modulus of the hot-pressed samples increased with compaction temperature initially due to the improved interlayer bonding and decreased after a maximum at 150°C because of partial melting of the reinforcement phase. The calender roller technique exhibited to have smaller processing temperature window as the pressure is only applied for a short time and the fabrics start to shrink with increasing the processing temperature. The need for constraining the fabrics through the process is therefore found to be paramount. The Vacuum bag results showed this technique to be the least efficient method because of the low compaction pressure. Microscopic images and void content measurement of the consolidated samples further validate the results from tensile testing.

Role of low O 2 pressure and growth temperature on electrical transport of PLD grown ZnO thin films on Si substrates

NASA Astrophysics Data System (ADS)

Pandis, Ch.; Brilis, N.; Tsamakis, D.; Ali, H. A.; Krishnamoorthy, S.; Iliadis, A. A.

2006-06-01

Undoped ZnO thin films have been grown on (100) Si substrates by pulsed laser deposition. The effect of growth parameters such as temperature, O 2 partial pressure and laser fluence on the structural and electrical properties of the films has been investigated. It is shown that the well-known native n-type conductivity, attributed to the activation of hydrogenic donor states, exhibits a conversion from n-type to p-type when the O 2 partial pressure is reduced from 10 -4 to 10 -7 Torr at growth temperatures lower than 400 °C. The p-type conductivity could be attributed to the dominant role of the acceptor Zn vacancies for ZnO films grown at very low O 2 pressures.

Oxygen transport membrane based advanced power cycle with low pressure synthesis gas slip stream

DOEpatents

Kromer, Brian R.; Litwin, Michael M.; Kelly, Sean M.

2016-09-27

A method and system for generating electrical power in which a high pressure synthesis gas stream generated in a gasifier is partially oxidized in an oxygen transport membrane based reactor, expanded and thereafter, is combusted in an oxygen transport membrane based boiler. A low pressure synthesis gas slip stream is split off downstream of the expanders and used as the source of fuel in the oxygen transport membrane based partial oxidation reactors to allow the oxygen transport membrane to operate at low fuel pressures with high fuel utilization. The combustion within the boiler generates heat to raise steam to in turn generate electricity by a generator coupled to a steam turbine. The resultant flue gas can be purified to produce a carbon dioxide product.

Simultaneous velocity and pressure quantification using pressure-sensitive flow tracers in air

NASA Astrophysics Data System (ADS)

Zhang, Peng; Peterson, Sean; Porfiri, Maurizio

2017-11-01

Particle-based measurement techniques for assessing the velocity field of a fluid have advanced rapidly over the past two decades. Full-field pressure measurement techniques have remained elusive, however. In this work, we aim to demonstrate the possibility of direct simultaneous planar velocity and pressure measurement of a high speed aerodynamic flow by employing novel pressure-sensitive tracer particles for particle image velocimetry (PIV). Specifically, the velocity and pressure variations of an airflow through a converging-diverging channel are studied. Polystyrene microparticles embedded with a pressure-sensitive phosphorescent dye-platinum octaethylporphyrin (PtOEP)-are used as seeding particles. Due to the oxygen quenching effect, the emission lifetime of PtOEP is highly sensitive to the oxygen concentration, that is, the partial pressure of oxygen, in the air. Since the partial pressure of oxygen is linearly proportional to the air pressure, we can determine the air pressure through the phosphorescence emission lifetime of the dye. The velocity field is instead obtained using traditional PIV methods. The particles have a pressure resolution on the order of 1 kPa, which may be improved by optimizing the particle size and dye concentration to suit specific flow scenarios. This work was supported by the National Science Foundation under Grant Number CBET-1332204.

Partial recovery of peristalsis after myotomy for achalasia; more the rule than the exception

PubMed Central

Roman, Sabine; Kahrilas, Peter J; Mion, François; Nealis, Thomas B; Soper, Nathaniel J; Poncet, Gilles; Nicodème, Frédéric; Hungness, Eric; Pandolfino, John E

2013-01-01

Hypothesis: Myotomy that alleviates the esophagogastric junction (EGJ) outflow obstruction in achalasia might improve peristalsis. Design: Retrospective study Setting: Two tertiary hospitals (Chicago, USA and Lyon, France) Patients: Thirty patients (18 males; mean age 43 years, range 17-78) were included from 2004 to 2012: 8 type 1 achalasia (27%), 17 type 2 (57%) and 5 type 3 (16%) according to the Chicago Classification. Interventions: Esophageal high resolution manometry (HRM) before and after laparoscopic or endoscopic myotomy. Main outcomes measures: The integrity of peristalsis was characterized as intact, weak, frequent failed, absent, or premature contractions. Results: Whereas peristaltic fragments were evident only in patients with type 3 achalasia before treatment, intact, weak, or frequent failed peristalsis was encountered in 63% of type 1, 47% of type 2 and 80% of type 3 achalasia after myotomy. One type 3 patient had distal esophageal spasm after treatment. In patients with a post-myotomy integrated relaxation pressure (IRP) <15 mmHg, only 10 (40%) persisted in having absent peristalsis. Panesophageal pressurization disappeared after myotomy in 16 of 19 patients. In the 5 patients with post-myotomy IRP >15 mmHg, 4 had weak peristalsis and one had absent peristalsis. Conclusion: Reduction or normalization of the EGJ relaxation pressure achieved by myotomy in achalasia patients was associated with partial recovery of peristalsis in some patients suggesting that the disease process progresses from the EGJ to the esophageal body. Whether or not the return of peristalsis is predictive of an improved therapeutic outcome requires further study. PMID:23426591

Ureilite petrogenesis: A limited role for smelting during anatexis and catastrophic disruption

NASA Astrophysics Data System (ADS)

Warren, Paul H.; Huber, Heinz

2006-06-01

A popular model for ureilites assumes that during anatexis in an asteroidal mantle, pressure-buffered equilibrium smelting (partial reduction coincident with partial melting) engendered their conspicuous mafic-silicate-core mg diversity (75-96 mol%). Several mass-balance problems arise from this hypothesis. Smelting inevitably consumes a large proportion of any plausible initial carbon while generating significant proportions of Fe metal and copious proportions of CO gas. The most serious problem concerns the yield of CO gas. If equilibrium smelting produced the ureilites' entire 21 mol% range in olivine-core mg, the proportion of gas within the asteroidal mantle (assuming plausibly low pressure <˜80 bar) should have reached ≥85 vol%. Based on the remarkably stepwise cooling history inferred from ureilite texture and mineralogy, a runaway, CO-leaky process that can loosely be termed smelting appears to have occurred, probably triggered by a major impact. The runaway scenario appears likely because, by Le Châtelier's principle, CO leakage would tend to accelerate the smelting process. Also, the copious volumes of gas produced by smelting would have led to explosive, mass-leaky eruptions into the vacuum surrounding the asteroid. Loss of mass would mean diminution of interior pressure, which would induce further smelting, leading to further loss of mass (basalt), and so on. Such a disruptive runaway process may have engendered the ureilites' distinctive reduced olivine rims. But the only smelting, according to this scenario, was a short-lived disequilibrium process that reduced only the olivine rims, not the cores; and the ureilites were cooling, not melting, during the abortive "smelting" episode.

Bronchoalveolar lavage with diluted porcine surfactant in mechanically ventilated term infants with meconium aspiration syndrome.

PubMed

Lista, Gianluca; Bianchi, Silvia; Castoldi, Francesca; Fontana, Paola; Cavigioli, Francesco

2006-01-01

To evaluate the efficacy and safety of bronchoalveolar lavage (BAL) with diluted porcine surfactant in mechanically ventilated term infants with severe acute respiratory distress syndrome (ARDS) due to meconium aspiration syndrome (MAS). Eight consecutive mechanically ventilated term infants with severe ARDS due to MAS underwent BAL with 15 mL/kg of diluted (5.3mg phospholipid/mL) surfactant saline suspension (porcine surfactant [Curosurf]). Treatment was administered slowly in aliquots of 2.5 mL. The mean age of neonates at treatment was 3.5 (range 1-8) hours. Heart rate, systemic blood pressure and oxygen saturation were monitored continuously. Arterial blood gases were measured immediately before treatment, and again at 3 and 6 hours post-treatment. Chest x-rays were taken 6 and 24 hours after treatment. Radiological improvement was evident in all eight patients 6 hours post-treatment. Compared with pre-BAL values, significant improvements (p < 0.05) in mean values for partial pressure of oxygen in arterial blood, partial pressure of carbon dioxide in arterial blood, pH, arterial/alveolar O2 ratio and oxygenation index were documented at 3 and 6 hours after BAL. In all patients, tracheal fluids that had been meconium-stained prior to BAL were clear of meconium after BAL. Only one patient required nitric oxide therapy for transient pulmonary hypertension. No adverse sequelae of treatment occurred during the study. BAL with dilute porcine surfactant administered slowly in 2.5 mL aliquots improved oxygenation and chest x-ray findings, without causing major adverse effects, in mechanically ventilated term infants with ARDS due to MAS.

Low Pressure-High Temperature Metamorphism and the Advection of Heat to the Continental Crust: A Case Study from Northwest New Guinea

NASA Astrophysics Data System (ADS)

Jost, B.; Webb, M.; White, L. T.

2017-12-01

In northwest New Guinea, Palaeozoic basement rocks forming part of the northern margin of the Australian continent are exposed in a rugged mountain range. This remote and understudied region provides a unique window into the complex Palaeozoic evolution and tectonic history of this region, which we help unravel with new field, petrographic, geochemical, and geochronological data. The basement rocks consist of extensive meta-turbidites that were subject to low pressure-high temperature metamorphism along their eastern margin. They are cross-cut by predominantly acidic granitoids. U-Pb zircon dating reveals that these granitoids intruded in three episodes in the Devonian-Carboniferous, the Carboniferous, and the Triassic. The first episode has not previously been reported in the region. The granitoids are strongly peraluminous, suggesting that partial melting of the meta-sedimentary country rock contributed to their petrogenesis (S-type). The occurrence and character of country rock xenoliths and migmatites supports this interpretation. Equilibrium thermodynamic modelling of the metapelites and the migmatites indicates that a substantial amount of heat was added to the lower and middle crust to cause partial melting and regional metamorphism at relatively low pressure. We propose repeated intrusion of hot magma as the mechanism responsible for advecting the necessary heat from the mantle. This likely occurred in an active continental margin setting during the Devonian-Carboniferous and the Triassic, possibly separated by an interval of magmatic quiescence during most of the Permian. New biostratigraphic and low-temperature thermochronological data reveal very recent Pliocene-Pleistocene uplift and unroofing of these basement rocks.

Cystic fibrosis airway secretions exhibit mucin hyperconcentration and increased osmotic pressure

PubMed Central

Henderson, Ashley G.; Ehre, Camille; Button, Brian; Abdullah, Lubna H.; Cai, Li-Heng; Leigh, Margaret W.; DeMaria, Genevieve C.; Matsui, Hiro; Donaldson, Scott H.; Davis, C. William; Sheehan, John K.; Boucher, Richard C.; Kesimer, Mehmet

2014-01-01

The pathogenesis of mucoinfective lung disease in cystic fibrosis (CF) patients likely involves poor mucus clearance. A recent model of mucus clearance predicts that mucus flow depends on the relative mucin concentration of the mucus layer compared with that of the periciliary layer; however, mucin concentrations have been difficult to measure in CF secretions. Here, we have shown that the concentration of mucin in CF sputum is low when measured by immunologically based techniques, and mass spectrometric analyses of CF mucins revealed mucin cleavage at antibody recognition sites. Using physical size exclusion chromatography/differential refractometry (SEC/dRI) techniques, we determined that mucin concentrations in CF secretions were higher than those in normal secretions. Measurements of partial osmotic pressures revealed that the partial osmotic pressure of CF sputum and the retained mucus in excised CF lungs were substantially greater than the partial osmotic pressure of normal secretions. Our data reveal that mucin concentration cannot be accurately measured immunologically in proteolytically active CF secretions; mucins are hyperconcentrated in CF secretions; and CF secretion osmotic pressures predict mucus layer–dependent osmotic compression of the periciliary liquid layer in CF lungs. Consequently, mucin hypersecretion likely produces mucus stasis, which contributes to key infectious and inflammatory components of CF lung disease. PMID:24892808

Surfactant-free synthesis of silica aerogel microspheres with hierarchically porous structure.

PubMed

Zhang, Yulu; Wang, Jin; Zhang, Xuetong

2018-04-01

In this work, we developed a new method to synthesize silica aerogel microspheres via ambient pressure drying (APD) process without applying any surfactants and mechanical stirring. An ethanol solution of partially hydrolyzed, partially condensed silica (CS) was used as precursor in the synthesis, the water-repellent n-Heptane as solvent, while the water-soluble ammonia gas (NH 3 ) as catalyst. After a fast sol-gel process and APD process, aerogel microspheres were obtained in the form of white powder with packing density ranged from 62 mg/cm 3 to 230 mg/cm 3 for different samples. The SEM images exhibited fine spherical morphology for these aerogel microparticles, and their statistical average particle diameter ranged from 0.8 μm to 1.5 μm. Besides, according to the analysis of N 2 adsorption-desorption isotherms, the BET surface area of these aerogel microspheres was in the range of 800-960 m 2 /g, and a considerable volume of micropores was detected along with the abundant mesospores in these microspheres, which was further confirmed by the TEM image and SAXS curve. Based on the very limited solubility of NH 3 in the reaction system, a non-emulsion formation mechanism was proposed to illustrate the formation of these aerogel microspheres. Copyright © 2018 Elsevier Inc. All rights reserved.

Partial melting of TTG gneisses: crustal contamination and the production of granitic melts

NASA Astrophysics Data System (ADS)

Meade, F. C.; Masotta, M.; Troll, V. R.; Freda, C.; Johnson, T. E.; Dahren, B.

2011-12-01

Understanding partial melting of ancient TTG gneiss terranes is crucial when considering crustal contamination in volcanic systems, as these rocks are unlikely to melt completely at magmatic temperatures (1000-1200 °C) and crustal pressures (<500 MPa). Variations in the bulk composition of the gneiss, magma temperature, pressure (depth) and the composition and abundance of any fluids present will produce a variety of melt compositions, from partial melts enriched in incompatible elements to more complete melts, nearing the bulk chemistry of the parent gneiss. We have used piston cylinder experiments to simulate partial melting in a suite of 12 gneisses from NW Scotland (Lewisian) and Eastern Greenland (Ammassalik, Liverpool Land) under magma chamber temperature and pressure conditions (P=200 MPa, T=975 °C). These gneisses form the basement to much of the North Atlantic Igneous Province, where crustal contamination of magmas was commonplace but the composition of the crustal partial melts are poorly constrained [1]. The experiments produced partial melts in all samples (e.g. Fig 1). Electron microprobe analyses of glasses indicate they are compositionally heterogeneous and are significantly different from the whole rock chemistry of the parent gneisses. The melts have variably evolved compositions but are typically trachy-dacitic to rhyolitic (granitic). This integrated petrological, experimental and in-situ geochemical approach allows quantification of the processes of partial melting of TTG gneiss in a volcanic context, providing accurate major/trace element and isotopic (Sr, Pb) end-members for modeling crustal contamination. The experimental melts and restites will be compared geochemically with a suite of natural TTG gneisses, providing constraints on the extent to which the gneisses have produced and subsequently lost melt. [1] Geldmacher et al. (2002) Scottish Journal of Geology, v.38, p.55-61.

Experimental study and thermodynamic modeling of the phase relation in the Fe-S-Si system with implications for the distribution of S and Si in a partially solidified core

NASA Astrophysics Data System (ADS)

Tao, R.; Fei, Y.

2017-12-01

Planetary cooling leads to solidification of any initially molten metallic core. Some terrestrial cores (e.g. Mercury) are formed and differentiated under relatively reduced conditions, and they are thought to be composed of Fe-S-Si. However, there are limited understanding of the phase relations in the Fe-S-Si system at high pressure and temperature. In this study, we conducted high-pressure experiments to investigate the phase relations in the Fe-S-Si system up to 25 GPa. Experimental results show that the liquidus and solidus in this study are slightly lower than those in the Fe-S binary system for the same S concentration in liquid at same pressure. The Fe3S, which is supposed to be the stable sub-solidus S-bearing phase in the Fe-S binary system above 17 GPa, is not observed in the Fe-S-Si system at 21 GPa. Almost all S prefers to partition into liquid, while the distribution of Si between solid and liquid depends on experimental P and T conditions. We obtained the partition coefficient log(KDSi) by fitting the experimental data as a function of P, T and S concentration in liquid. At a constant pressure, the log(KDSi) linearly decreases with 1/T(K). With increase of pressure, the slopes of linear correlation between log(KDSi) and 1/T(K) decreases, indicating that more Si partitions into solid at higher pressure. In order to interpolate and extrapolate the phase relations over a wide pressure and temperature range, we established a comprehensive thermodynamic model in the Fe-S-Si system. The results will be used to constrain the distribution of S and Si between solid inner core and liquid outer core for a range of planet sizes. A Si-rich solid inner core and a S-rich liquid outer core are suggested for an iron-rich core.

The Stability of Hydrous Silicates in Earth's Lower Mantle: Experimental constraints from the System MgO-Al2O3-SiO2-H2O

NASA Astrophysics Data System (ADS)

Walter, M. J.; Thomson, A. R.; Wang, W.; Lord, O. T.; Kleppe, A. K.; Ross, J.; Kohn, S. C.

2014-12-01

Laser-heated diamond anvil cell experiments were performed at pressures from ~ 30 to 125 GPa on bulk compositions in the system MgO-Al2O3-SiO2-H2O (MASH) to constrain the stability of hydrous phases in Earth's lower mantle. Phase identification in run products by synchrotron powder diffraction reveals a consistent set of stability relations for the high-pressure, dense hydrous silicate phases D and H. Experiments show that aluminous phase D is stable to ~ 55 GPa. Aluminous phase H becomes stable at ~ 40 GPa and remains stable to higher pressures throughout the lower mantle depth range in both model peridotitic and basaltic lithologies. Preliminary FEG-probe analyses indicate that Phase H is alumina-rich at ~ 50 GPa, with only 5 to 10 wt% each of MgO and SiO2. Variations in ambient unit cell volumes show that Mg-perovskite becomes more aluminous with pressure throughout the pressure range studied, and that Phase H may become more Mg- and Si-rich with pressure. We also find that at pressures above ~ 90 GPa stishovite is replaced in Si-rich compositions by seifertite, at which point there is a corresponding increase in the Al-content of phase H. The melting curves of MASH compositions have been determined using thermal perturbations in power versus temperature curves, and are observed to be shallow with dT/dP slopes of ~ 4K/GPa. Our results show that hydrated peridotitic or basaltic compositions in the lower mantle should be partially molten at all depths along an adiabatic mantle geotherm. Aluminous Phase H will be stable in colder, hydrated subducting slabs, potentially to the core-mantle boundary. Thus, aluminous phase H is the primary vessel for transport of hydrogen to the deepest mantle, but hydrous silicate melt will be the host of hydrogen at ambient mantle temperatures.

Measurement of entropy generation within bypass transitional flow

NASA Astrophysics Data System (ADS)

Skifton, Richard; Budwig, Ralph; McEligot, Donald; Crepeau, John

2012-11-01

A flat plate made from quartz was submersed in the Idaho National Laboratory's Matched Index of Refraction (MIR) flow facility. PIV was utilized to capture spatial vectors maps at near wall locations with five to ten points within the viscous sublayer. Entropy generation was calculated directly from measured velocity fluctuation derivatives. Two flows were studied: a zero pressure gradient and an adverse pressure gradient (β = -0.039). The free stream turbulence intensity to drive bypass transition ranged between 3% (near trailing edge) and 8% (near leading edge). The pointwise entropy generation rate will be utilized as a design parameter to systematically reduce losses. As a second observation, the pointwise entropy can be shown to predict the onset of transitional flow. This research was partially supported by the DOE EPSCOR program, grant DE-SC0004751 and by the Idaho National Laboratory. Center for Advanced Energy Studies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dyachenko, Sergey A.; Zlotnik, Anatoly; Korotkevich, Alexander O.

Here, we develop an operator splitting method to simulate flows of isothermal compressible natural gas over transmission pipelines. The method solves a system of nonlinear hyperbolic partial differential equations (PDEs) of hydrodynamic type for mass flow and pressure on a metric graph, where turbulent losses of momentum are modeled by phenomenological Darcy-Weisbach friction. Mass flow balance is maintained through the boundary conditions at the network nodes, where natural gas is injected or withdrawn from the system. Gas flow through the network is controlled by compressors boosting pressure at the inlet of the adjoint pipe. Our operator splitting numerical scheme ismore » unconditionally stable and it is second order accurate in space and time. The scheme is explicit, and it is formulated to work with general networks with loops. We test the scheme over range of regimes and network configurations, also comparing its performance with performance of two other state of the art implicit schemes.« less

Shock-induced CO2 loss from CaCO3: Implications for early planetary atmospheres

NASA Technical Reports Server (NTRS)

Lange, M. A.; Ahrens, T. J.

1984-01-01

Recovered samples from shock recovery experiments on single crystal calcite were subjected to thermogravimetric analysis to determine the amount of post-shock CO2, the decarbonization interval and the activation energy, for the removal of remaining CO2 in shock-loaded calcite. Comparison of post-shock CO2 with that initially present determines shock-induced CO2 loss as a function of shock pressure. Incipient to complete CO2 loss occurs over a pressure range of approximately 10 to approximately 70 GPa. Optical and scanning electron microscopy reveal structural changes, which are related to the shock-loading. The occurrence of dark, diffuse areas, which can be resolved as highly vesicular areas as observed with a scanning electron microscope are interpreted as representing quenched partial melts, into which shock-released CO2 was injected. The experimental results are used to constrain models of shock-produced, primary CO2 atmospheres on the accreting terrestrial planets.

Contrast Gain Control in Auditory Cortex

PubMed Central

Rabinowitz, Neil C.; Willmore, Ben D.B.; Schnupp, Jan W.H.; King, Andrew J.

2011-01-01

Summary The auditory system must represent sounds with a wide range of statistical properties. One important property is the spectrotemporal contrast in the acoustic environment: the variation in sound pressure in each frequency band, relative to the mean pressure. We show that neurons in ferret auditory cortex rescale their gain to partially compensate for the spectrotemporal contrast of recent stimulation. When contrast is low, neurons increase their gain, becoming more sensitive to small changes in the stimulus, although the effectiveness of contrast gain control is reduced at low mean levels. Gain is primarily determined by contrast near each neuron's preferred frequency, but there is also a contribution from contrast in more distant frequency bands. Neural responses are modulated by contrast over timescales of ∼100 ms. By using contrast gain control to expand or compress the representation of its inputs, the auditory system may be seeking an efficient coding of natural sounds. PMID:21689603

STRUCTURE AND PHYSICAL PROPERTIES OF SOLID AND LIQUID VANADIUM PENTOXIDE.

DTIC Science & Technology

The electrical resistivity of near-stoichiometric crystalline V2O5 was measured as a function of crystal orientation and oxygen partial pressure from...25C to 300C. Conductivity is insensitive to ambient atmosphere. The activation energy for conduction is 0.20 ev. Molten V2O5 , however, is...sensitive to oxygen partial pressure. Its conductivity is proportional to P-O2 to the -1/6th power. Anomalously high electrical resistivity was observed for glassy V2O5 films. (Author)

Assessment of Correlation of Distal Mean Arterial Pressure with Aortic Blood Flow during Partial Resuscitative Endovascular Balloon Aortic Occlusion (P-REBOA) in a Swine (Sus scrofa) Controlled Hemorrhage Model

DTIC Science & Technology

2017-11-06

60th Medical Group (AMC), Travis AFB, CA INSTITUTIONAL ANIMAL CARE AND USE COMMITTEE (IACUC) FINAL REPORT SUMMARY (Please type all information. Use...Pressure with Aortic Blood Flow during Partial Resuscitative Endovascular Balloon Aortic Occlusion (P-REBOA) in a Swine (Sus scrofa) Controlled Hemorrhage...to Date Sus scrofa 8 8 2. PROTOCOL TYPE /CHARACTERISTICS: (Check all applicable terms in EACH column) _ Training: Live Animal Medical Readiness

Shear Banding in a Partially Molten Mantle

NASA Astrophysics Data System (ADS)

Alisic, L.; Rudge, J. F.; Wells, G.; Katz, R. F.; Rhebergen, S.

2013-12-01

We investigate the nonlinear behaviour of partially molten mantle material under shear. Numerical models of compaction and advection-diffusion of a porous matrix with a spherical inclusion are built using the automated code generation package FEniCS. The time evolution of melt distribution with increasing shear in these models is compared to laboratory experiments that show high-porosity shear banding in the medium and pressure shadows around the inclusion. We focus on understanding the interaction between these shear bands and pressure shadows as a function of rheological parameters.

The Pacman Perforator-Based V-Y Advancement Flap for Reconstruction of Pressure Sores at Different Locations.

PubMed

Bonomi, Stefano; Salval, André; Brenta, Federica; Rapisarda, Vincenzo; Settembrini, Fernanda

2016-09-01

Many procedures have been proposed for the treatment of pressure sores, and V-Y advancement flaps are widely used to repair a defect. Unfortunately, the degree of mobility of a V-Y advancement flap is dependent on the laxity of the underlying subcutaneous tissue. This is an important disadvantage of traditional V-Y advancement flap and limits its use.We used V-Y advancement flaps as perforator-based to overcome mobility restriction problem, with a further modification (Pacman-like shape) to improve the covering surface area of the flap. Between January 2012 and December 2014, the authors used 37 V-Y Pacman perforator-based flaps in 33 consecutive patients for coverage of defects located at sacral (n = 21), ischial (n = 13), trochanter (n = 1) regions. There were 27 male and 6 female patients with a mean age of 49.9 years (range, 15-74 years). All flaps survived completely (92.3%) except 3 in which one of them had undergone total necrosis due to hematoma and the other 2 had partial necrosis. No venous congestion was observed. The mean follow-up period was 14.9 months (range, 2-38 months). No flap surgery-related mortality or recurrence of pressure sores was noted. The V-Y Pacman perforator-based advancement flaps are safe and very effective for reconstruction of pressure sores at various regions. The advantage of our modification procedure include shorter operative time, lesser pedicle dissection, low donor site morbidity, good preservation of muscle, and offers remarkable excursion to the V-Y flap, which make the V-Y Pacman perforator-based flaps an excellent choice for large pressure sore coverage.

Kinetics and selectivity of 2-propanol conversion on oxidized anatase TiO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rekoske, J.E.; Barteau, M.A.

1997-01-01

The steady-state kinetics of 2-propanol decomposition on oxidized anatase TiO{sub 2} have been determined at temperatures ranging from 448 to 598 K and 2-propanol partial pressures from 8.9 to 102.7 Torr. The effects of the addition of O{sub 2} and water to the carrier gas were also investigated. The steady-state reaction results primarily in the formation of a dehydration product, propylene, and a dehydrogenation product, acetone, with small amounts of carbon oxides also being observed. Depending on the reaction conditions, the selectivity to either propylene or acetone can range between 5 and 95%. The rate of dehydrogenation increases dramatically withmore » the addition of both O{sub 2} and water, while the dehydration rate is unaffected by their presence. Accordingly, the kinetics of 2-propanol decomposition were investigated using both air and an inert carrier. Using air as the carrier gas, the dehydration and dehydrogenation reactions were determined to be approximately one-half order with respect to 2-propanol partial pressure. The activation energies determined for the two processes are substantially different, 68 kJ mol{sup -1} for dehydrogenation and 130 kJ mol{sup -1} for dehydration, as evidenced by the strong temperature dependence of the decomposition selectivity. Using an inert carrier, the reaction kinetics depend in a complex fashion on the conversion of 2-propanol. The dependence on conversion was found to arise from the influence of water on the dehydrogenation kinetics. The presence of water, whether produced by 2-propanol dehydration or added independently, was found to increase the rate of 2-propanol dehydrogenation. 48 refs., 9 figs., 6 tabs.« less

Geochemistry of peraluminous tonalite and trondhjemite, the Cornucopia stock, Blue Mountains, NE Oregon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, K.; Barnes, C.G.; Kistler, R.W.

1993-04-01

The Cretaceous Cornucopia stock was emplaced into a greenschist-facies Permo-Triassic arc terrane. The stock comprises five distinct units: hornblende biotite tonalite, biotite trondhjemite, and three cordierite biotite trondhjemites, all with late dacitic and granitic dikes. Tonalite and trondhjemites span a narrow range of SiO[sub 2] contents and exhibit characteristics of a high-Al tonalite-trondhjemite-dacite (TTD) suite: LREE enrichment, low Y (< 15 ppm), Nb (< 10 ppm), Rb/Sr ([le]0.04), and high Sr (550--800 ppm). Euhedral cordierite phenocrysts imply the trondhjemites were H[sub 2]O-rich and were emplaced at pressures of < 2 kbars. Trace element and REE models are consistent with anmore » origin for the tonalite and trondhjemites by variable degrees (< 40%) of partial melting of a low-K tholeiitic source, with a garnet amphibolite residuum. Individual units are not related by fractional crystallization, but instead represent distinct partial melts. High Sr contents in the TTD rocks, the presence of residual garnet, and abundant residual amphibole implied by partial melting models suggest that melting occurred under H[sub 2]O-rich conditions at P [ge] 8--10 kbars.« less

The development of a three-dimensional partially elliptic flow computer program for combustor research

NASA Technical Reports Server (NTRS)

Pan, Y. S.

1978-01-01

A three dimensional, partially elliptic, computer program was developed. Without requiring three dimensional computer storage locations for all flow variables, the partially elliptic program is capable of predicting three dimensional combustor flow fields with large downstream effects. The program requires only slight increase of computer storage over the parabolic flow program from which it was developed. A finite difference formulation for a three dimensional, fully elliptic, turbulent, reacting, flow field was derived. Because of the negligible diffusion effects in the main flow direction in a supersonic combustor, the set of finite-difference equations can be reduced to a partially elliptic form. Only the pressure field was governed by an elliptic equation and requires three dimensional storage; all other dependent variables are governed by parabolic equations. A numerical procedure which combines a marching integration scheme with an iterative scheme for solving the elliptic pressure was adopted.

Measuring N2 Pressure Using Cyanobacteria

NASA Astrophysics Data System (ADS)

Silverman, S. N.; Kopf, S.; Gordon, R.; Bebout, B.; Som, S.

2017-11-01

We have shown that cyanobacteria can record information about N2 partial pressure both morphologically and isotopically, and thus may serve as useful geobarometers to help us better understand Earth's ancient atmosphere.

Effects of changing body position on oxygenation and arterial blood pressures in foals anesthetized with guaifenesin, ketamine, and xylazine.

PubMed

Braun, Christina; Trim, Cynthia M; Eggleston, Randy B

2009-01-01

To investigate the impact of a change in body position on blood gases and arterial blood pressures in foals anesthetized with guaifenesin, ketamine, and xylazine. Prospective, randomized experimental study. Twelve Quarter Horse foals, age of 5.4 +/-0.9 months and weighing 222 +/- 48 kg. Foals were anesthetized with guaifenesin, ketamine, and xylazine for 40 minutes in lateral recumbency and then assigned to a change in lateral recumbency after hoisting (Group 1, n = 6), or no change (Group 2, n = 6). Oxygen 15 L minute(-1) was insufflated into the endotracheal tube throughout anesthesia. Arterial blood pressure, heart rate, respiratory rate (f(R)), inspired fraction of oxygen (FIO(2)), and end-tidal carbon dioxide (PE'CO(2)) were measured every 5 minutes. Arterial pH and blood gases [arterial partial pressure of oxygen (PaO(2)), arterial partial pressure of carbon dioxide (PaCO(2))] were measured at 10, 30, and 40 minutes after induction, and 5 minutes after hoisting. Alveolar dead space ventilation and PaO(2)/FIO(2) were calculated. Two repeated measures models were used. All hypothesis tests were two-sided and significance level was alpha = 0.05. All values are presented as least square means +/- SE. Values at time-matched points from the two groups were not significantly different so they were combined. Arterial partial pressure of oxygen decreased significantly from 149 +/- 14.4 mmHg before hoisting to 92 +/- 11.6 mmHg after hoisting (p = 0.0013). The PaO(2)/FIO(2) ratio decreased from 275 +/- 30 to 175 +/- 24 (p = 0.0055). End-tidal carbon dioxide decreased significantly from 48.7 +/- 1.6 to 44.5 +/- 1.2 mmHg (p = 0.021). Arterial partial pressure of carbon dioxide, blood pressures and heart rates measured 5 minutes after hoisting were not different from measurements obtained before hoisting. Hoisting decreased PaO(2) in anesthetized healthy foals. Administration of supplemental oxygen is recommended to counter the decrease in oxygenation and PaO(2) measurement is necessary to detect early changes.

The System Forsterite-Diopside-Enstatite up to 70 kbar and its Significance to the Genesis of Komatiites

NASA Astrophysics Data System (ADS)

Dasgupta, S.; Gupta, A. K.

2011-12-01

Liquidus phase relations in the system forsterite-diopside-enstatite has been made at 70 kbar under anhydrous conditions using a Walker-type multi-anvil high pressure apparatus. Positions of the pseudoeutectic/ invariant, minimum points and amount of solid solutions of appearing phases are summarized in table 1. Comparison of these phase relations with those conducted by previous investigators at lower pressures and temperatures shows that the fosterite-pyroxene liquidus boundary shifts toward forsterite and away from the diopside apex with increasing pressure. Microprobe analyses indicate that the maximum amount of MgSiO3 that can be incorporated in diopside increases with pressure, and at the solidus (70 kbar, 2010°C), it is about 82%. On the basis of EPMA analyses of coexisting liquid and crystalline phases, three-phase triangles have been constructed. It is observed that at 70 kbar, the early partial melt generated from a model peridotite does not precipitate orthopyroxene. If such a melt instead of crystallizing in-situ, ascend to the surface, then the polybaric-polythermal crystallization path should never intersect the liquidus phase field of orthopyroxene, enstatitess may then appear in the solidus as an exsolution product. Our calculation shows that at 31% partial melting of a model mantle, orthopyroxene should appear as a liquidus phase. With further increase in the degree of partial melting (42-60%), proportion of orthopyroxene crystallizing from the melt progressively increases. With reference to the above discussion we propose that the Gorgona komatiites which are primarily orthopyroxene-deficient komatiites, are an outcome of low degree of partial melting, whereas the orthopyroxene-bearing Commondale komatiites of the southern Kaapvaal Craton, South Africa, are the outcome of a larger degree of partial melting, both generated from melting of an anhydrous mantle.

Characterization of Single Phase and Two Phase Heat and Momentum Transport in a Spiraling Radial Inow Microchannel Heat Sink

NASA Astrophysics Data System (ADS)

Ruiz, Maritza

Thermal management of systems under high heat fluxes on the order of hundreds of W/cm2 is important for the safety, performance and lifetime of devices, with innovative cooling technologies leading to improved performance of electronics or concentrating solar photovoltaics. A novel, spiraling radial inflow microchannel heat sink for high flux cooling applications, using a single phase or vaporizing coolant, has demonstrated enhanced heat transfer capabilities. The design of the heat sink provides an inward swirl flow between parallel, coaxial disks that form a microchannel of 1 cm radius and 300 micron channel height with a single inlet and a single outlet. The channel is heated on one side through a conducting copper surface, and is essentially adiabatic on the opposite side to simulate a heat sink scenario for electronics or concentrated photovoltaics cooling. Experimental results on the heat transfer and pressure drop characteristics in the heat sink, using single phase water as a working fluid, revealed heat transfer enhancements due to flow acceleration and induced secondary flows when compared to unidirectional laminar fully developed flow between parallel plates. Additionally, thermal gradients on the surface are small relative to the bulk fluid temperature gain, a beneficial feature for high heat flux cooling applications. Heat flux levels of 113 W/cm2 at a surface temperature of 77 deg C were reached with a ratio of pumping power to heat rate of 0.03%. Analytical models on single phase flow are used to explore the parametric trends of the flow rate and passage geometry on the streamlines and pressure drop through the device. Flow boiling heat transfer and pressure drop characteristics were obtained for this heat sink using water at near atmospheric pressure as the working fluid for inlet subcooling levels ranging from 20 to 80 deg C and mean mass flux levels ranging from 184-716 kg/m. 2s. Flow enhancements similar to singlephase flow were expected, as well as enhancements due to increased buoyant forces on vapor bubbles resulting from centripetal acceleration in the flow which will tend to draw the vapor towards the outlet. This can also aid in the reduction of vapor obstruction of the flow. The flow was identified as transitioning through three regimes as the heat rate was increased: partial subcooled flow boiling, oscillating boiling and fully developed flow boiling. During partial subcooled flow boiling, both forced convective and nucleate boiling effects are important. During oscillating boiling, the system fluctuated between partial subcooled flow boiling and fully developed nucleate boiling. Temperature and pressure oscillations were significant in this regime and are likely due to bubble constriction of flow in the microchannel. This regime of boiling is generally undesirable due to the large oscillations in temperatures and pressure and design constraints should be established to avoid large oscillations from occurring. During fully developed flow boiling, water vapor rapidly leaves the surface and the flow does not sustain large oscillations. Reducing inlet subcooling levels was found to reduce the magnitude of oscillations in the oscillating boiling regime. Additionally, reduced inlet subcooling levels reduced the average surface temperature at the highest heat flux levels tested when heat transfer was dominated by nucleate boiling, yet increased the average surface temperatures at low heat flux levels when heat transfer was dominated by forced convection. Experiments demonstrated heat fluxes up to 301 W/cm. 2at an average surface temperature of 134 deg C under partial subcooled flow boiling conditions. At this peak heat flux, the system required a pumping power to heat rate ratio of 0.01%. This heat flux is 2.4 times the typical values for critical heat flux in pool boiling under similar conditions.

Tested Demonstrations.

ERIC Educational Resources Information Center

Gilbert, George L.

1983-01-01

An apparatus is described in which effects of pressure, volume, and temperature changes on a gas can be observed simultaneously. Includes use of the apparatus in demonstrating Boyle's, Gay-Lussac's, and Charles' Laws, attractive forces, Dalton's Law of Partial pressures, and in illustrating measurable vapor pressures of liquids and some solids.…

Effect of prolonged hypokinesia on resistance of resistive vessels in rats

NASA Technical Reports Server (NTRS)

Saltykova, V. A.

1982-01-01

Under the effect of prolonged hypokinesia, the perfusion pressure in resistive vessels, measured under conditions of deep anesthesia and complete denervation, increased by approximately the same degree as arterial pressure in non-anesthetized animals. The increase in arterial, perfusion pressure and the resistance of resistive vessels in animals subjected to prolonged hypokinesia was accompanied by an increase in adrenoreactivity. During prolonged hypokinesia, partial obliteration of the vascular bed of the skeletal muscles plays a significant role in the observed increase in resistance of vessels of the extremities. The increase in adrenoreactivity of the vessels during hypokinesia may be realized as a partial case of an increase in the adrenoreactivity of structures whose innervation is disturbed.

Solution and shock-induced exsolution of argon in vitreous carbon

NASA Technical Reports Server (NTRS)

Gazis, Carey; Ahrens, Thomas J.

1991-01-01

To add to the knowledge of noble gas solution and exsolution in carbonaceus material, experiments were performed on vitreous carbon. Ar-rich vitreous carbon samples were prepared under vapor-saturated conditions using argon as the pressurizing medium. Solubility data were obtained for temperatures of 773 to 973 K and pressures of 250 to 1500 bars. Up to 7 wt pct Ar was dissolved in the carbon. The solubility data were compared to a thermodynamic model of argon atoms dissolving into a fixed population of 'holes' in the carbon. Two variations of the model yielded estimates of the enthalpy of solution of Ar in vitreous carbon equal to about -4700 cal/mole. Preliminary shock experiments showed that 28 percent of the total argon was released by driving 4 GPa shocks into the argon-rich carbon. It was demonstrated that shock-induced argon loss is not simply caused by the impact-induced diminution of grain size. The present value of shock pressure required for partial impact devolatilization of Ar from carbon is below the range (5-30 GPa) at which H2O is released from phyllosilicates.

Determination of oral mucosal Poisson's ratio and coefficient of friction from in-vivo contact pressure measurements.

PubMed

Chen, Junning; Suenaga, Hanako; Hogg, Michael; Li, Wei; Swain, Michael; Li, Qing

2016-01-01

Despite their considerable importance to biomechanics, there are no existing methods available to directly measure apparent Poisson's ratio and friction coefficient of oral mucosa. This study aimed to develop an inverse procedure to determine these two biomechanical parameters by utilizing in vivo experiment of contact pressure between partial denture and beneath mucosa through nonlinear finite element (FE) analysis and surrogate response surface (RS) modelling technique. First, the in vivo denture-mucosa contact pressure was measured by a tactile electronic sensing sheet. Second, a 3D FE model was constructed based on the patient CT images. Third, a range of apparent Poisson's ratios and the coefficients of friction from literature was considered as the design variables in a series of FE runs for constructing a RS surrogate model. Finally, the discrepancy between computed in silico and measured in vivo results was minimized to identify the best matching Poisson's ratio and coefficient of friction. The established non-invasive methodology was demonstrated effective to identify such biomechanical parameters of oral mucosa and can be potentially used for determining the biomaterial properties of other soft biological tissues.

Mass flow and velocity profiles in Neurospora hyphae: partial plug flow dominates intra-hyphal transport.

PubMed

Abadeh, Aryan; Lew, Roger R

2013-11-01

Movement of nuclei, mitochondria and vacuoles through hyphal trunks of Neurospora crassa were vector-mapped using fluorescent markers and green fluorescent protein tags. The vectorial movements of all three were strongly correlated, indicating the central role of mass (bulk) flow in cytoplasm movements in N. crassa. Profiles of velocity versus distance from the hyphal wall did not match the parabolic shape predicted by the ideal Hagen-Poiseuille model of flow at low Reynolds number. Instead, the profiles were flat, consistent with a model of partial plug flow due to the high concentration of organelles in the flowing cytosol. The intra-hyphal pressure gradients were manipulated by localized external osmotic treatments to demonstrate the dependence of velocity (and direction) on pressure gradients within the hyphae. The data support the concept that mass transport, driven by pressure gradients, dominates intra-hyphal transport. The transport occurs by partial plug flow due to the organelles in the cytosol.

Undergraduate students' misconceptions about respiratory physiology.

PubMed

Michael, J A; Richardson, D; Rovick, A; Modell, H; Bruce, D; Horwitz, B; Hudson, M; Silverthorn, D; Whitescarver, S; Williams, S

1999-12-01

Approximately 700 undergraduates studying physiology at community colleges, a liberal arts college, and universities were surveyed to determine the prevalence of our misconceptions about respiratory phenomena. A misconception about the changes in breathing frequency and tidal volume (physiological variables whose changes can be directly sensed) that result in increased minute ventilation was found to be present in this population with comparable prevalence (approximately 60%) to that seen in a previous study. Three other misconceptions involving phenomena that cannot be experienced directly and therefore were most likely learned in some educational setting were found to be of varying prevalence. Nearly 90% of the students exhibited a misconception about the relationship between arterial oxygen partial pressure and hemoglobin saturation. Sixty-six percent of the students believed that increasing alveolar oxygen partial pressure leads to a decrease in alveolar carbon dioxide partial pressure. Nearly 33% of the population misunderstood the relationship between metabolism and ventilation. The possible origins of these respiratory misconceptions are discussed and suggestions for how to prevent and/or remediate them are proposed.

Nanocrystalline films for gas-reactive applications

DOEpatents

Eastman, Jeffrey A.; Thompson, Loren J.

2004-02-17

A gas sensor for detection of oxidizing and reducing gases, including O.sub.2, CO.sub.2, CO, and H.sub.2, monitors the partial pressure of a gas to be detected by measuring the temperature rise of an oxide-thin-film-coated metallic line in response to an applied electrical current. For a fixed input power, the temperature rise of the metallic line is inversely proportional to the thermal conductivity of the oxide coating. The oxide coating contains multi-valent cation species that change their valence, and hence the oxygen stoichiometry of the coating, in response to changes in the partial pressure of the detected gas. Since the thermal conductivity of the coating is dependent on its oxygen stoichiometry, the temperature rise of the metallic line depends on the partial pressure of the detected gas. Nanocrystalline (<100 nm grain size) oxide coatings yield faster sensor response times than conventional larger-grained coatings due to faster oxygen diffusion along grain boundaries rather than through grain interiors.

A comparative study on NbOx films reactively sputtered from sintered and cold gas sprayed targets

NASA Astrophysics Data System (ADS)

Lorenz, Roland; O'Sullivan, Michael; Fian, Alexander; Sprenger, Dietmar; Lang, Bernhard; Mitterer, Christian

2018-04-01

The aim of this work is to evaluate novel cold gas sprayed Nb targets in a reactive sputter deposition process of thin films with respect to the widely used sintered Nb targets. With the exception of a higher target discharge voltage of ∼100 V for the cold gas sprayed targets and the thus higher film growth rate compared to sintered targets, NbOx films with comparable microstructure and properties were obtained for both target variants. The amorphous films with thicknesses between 2.9 and 4.9 μm present an optical shift from dark and non-transparent towards transparent properties, as the oxygen partial pressure increases. X-ray photoelectron spectroscopy confirms the occurrence of the Nb5+ oxidation state for the highest oxygen partial pressure, while Nb4+ is additionally present at lower oxygen partial pressure settings. With a maximal transparency of ∼80% and a refractive index of ∼2.5, the transparent films show characteristics similar to Nb2O5.

A flowing liquid test system for assessing the linearity and time-response of rapid fibre optic oxygen partial pressure sensors.

PubMed

Chen, R; Hahn, C E W; Farmery, A D

2012-08-15

The development of a methodology for testing the time response, linearity and performance characteristics of ultra fast fibre optic oxygen sensors in the liquid phase is presented. Two standard medical paediatric oxygenators are arranged to provide two independent extracorporeal circuits. Flow from either circuit can be diverted over the sensor under test by means of a system of rapid cross-over solenoid valves exposing the sensor to an abrupt change in oxygen partial pressure, P O2. The system is also capable of testing the oxygen sensor responses to changes in temperature, carbon dioxide partial pressure P CO2 and pH in situ. Results are presented for a miniature fibre optic oxygen sensor constructed in-house with a response time ≈ 50 ms and a commercial fibre optic sensor (Ocean Optics Foxy), when tested in flowing saline and stored blood. Copyright © 2012 Elsevier B.V. All rights reserved.