Artigos de revistas: "High O2 pressure"

1

Azyazov, V. N., M. V. Zagidullin, V. D. Nikolaev, M. I. Svistun e N. A. Khvatov. "Transport of high-pressure O2(1Δ)". Quantum Electronics 24, n.º 3 (31 de março de 1994): 229–32. http://dx.doi.org/10.1070/qe1994v024n03abeh000059.

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van Blankenstein, J. H., C. J. Slager, L. K. Soei, H. Boersma e P. D. Verdouw. "Effect of arterial blood pressure and ventilation gases on cardiac depression induced by coronary air embolism". Journal of Applied Physiology 77, n.º 4 (1 de outubro de 1994): 1896–902. http://dx.doi.org/10.1152/jappl.1994.77.4.1896.

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In this study the time course of cardiac depression after selective intracoronary injection of air bubbles was investigated in six anesthetized pigs (30 +/- 2 kg) with different mixtures of ventilation gases and different mean arterial blood pressures (MAP). Air bubbles of 150 microns diam were injected into the left anterior descending coronary artery (LADCA) in a volume of 2 microliters/kg body wt. In each animal an injection of air bubbles was applied during ventilation with N2-O2 and a MAP of 77 +/- 3 mmHg (N2-O2/low pressure) or 111 +/- 3 mmHg (N2-O2/high pressure) and during ventilation with pure O2 and a MAP of 77 +/- 3 mmHg (O2/low pressure) or 110 +/- 3 mmHg (O2/high pressure). Systemic hemodynamic variables such as left ventricular pressure, its peak first derivatives, and MAP changed < 10% after injection of air bubbles. During N2-O2/low pressure, systolic segment length shortening in the LADCA region (SS-LADCA) decreased from baseline and did not return to baseline within the 10 min after injection of air bubbles. During N2-O2/high pressure and O2/low pressure, SS-LADCA was decreased between 60 and 120 s, whereas for O2/high pressure this period was from 60 to 90 s. By calculating the time integral of the deviation from baseline of SS-LADCA, it could be demonstrated that the depression of regional myocardial function was less severe during O2/high pressure and O2/low pressure than during N2-O2/low pressure. We conclude that, when coronary air embolism occurs during hypertension and during ventilation with pure O2 instead of a normal N2-O2 mixture, the resulting depression of regional myocardial function is reduced.

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Levi, A., e D. Sasselov. "Partitioning of Atmospheric O₂ into High-pressure Ice in Ocean Worlds". Astrophysical Journal 926, n.º 1 (1 de fevereiro de 2022): 72. http://dx.doi.org/10.3847/1538-4357/ac4500.

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Abstract Planets with a few percent water by mass may have a high-pressure ice mantle separating the rocky interior from both the ocean and atmosphere. Here we examine whether the partitioning of O2 into high-pressure ice can constrain the atmospheric abundance of O2 produced by water photolysis in the atmosphere. We find that the partition coefficient of dissolved O2 between high-pressure ice and liquid water is about unity. We show that the solubility of O2 in high-pressure water ice yields an upper value for the atmospheric abundance of O2 that depends on the ocean surface temperature. The atmospheric pressure of O2 has a maximum of approximately 3000 bars. The latter drops to a few hundred bars as the surface temperature of the ocean approaches supercritical conditions.

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Silva, S. M., R. C. Herner e R. M. Beaudry. "407 Regulation of Carbon Flux as a Function of O2 and CO2 Atmospheres in Asparagus Tips". HortScience 34, n.º 3 (junho de 1999): 514B—514. http://dx.doi.org/10.21273/hortsci.34.3.514b.

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The purpose of this work was to investigate the influence of O2 and CO2 partial pressures on glycolytic carbon flux, phosphorylated intermediates, phosphate, pyrophosphate, and phosporylated nucleotides in asparagus spears tips stores at 1 °C. The effects of CO2 (0, 5, 10, and 20 kPa) combined with O2 pressures ranging from 0.1 to 16 kPa (1% O2 = 1.013 kPa O2 at 1 atm) were investigated. Spears were enclosed within a low-density polyethylene (LDPE) package (for the 5-, 10-, and 20-kPa CO2 treatments) having a surface area of 462 cm2 and enclosed in 1.95-L glass jars. Low O2 enhanced the interconversion of phosphoenolpyruvate (PEP) to pyruvate (PYR) and F6P to F1,6P2 relative to high O2. When spears tips at 16 kPa O2 were compared to those at harvest, little change occurred in the adenylate or phosphate pools. PPi and ATP contents decreased as the O2 partial pressure declined below 16 kPa O2. In general, as CO2 increased, PPi and ATP decreased, while Pi, ADP, and AMP increased. The adenylate energy charge (AEC) declined with a decline in the O2 partial pressure, declining most rapidly below 2 kPa O2. Low O2 reduced AEC relative to high O2. Increasing CO2 partial pressure reduced AEC, an effect not evident at lower O2. The data suggest low O2 and elevated CO2 impair oxidative phosphorylation and induce nonsustaining carbon metabolism, which may limit asparagus spear survival under O2-deficient conditions.

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Yang, Ming, Veena M. Bhopale e Stephen R. Thom. "Separating the roles of nitrogen and oxygen in high pressure-induced blood-borne microparticle elevations, neutrophil activation, and vascular injury in mice". Journal of Applied Physiology 119, n.º 3 (1 de agosto de 2015): 219–22. http://dx.doi.org/10.1152/japplphysiol.00384.2015.

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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.

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Howland, R. J., e K. Newman. "A high-precision automatic closed-circuit respirometer for small animals". Journal of Applied Physiology 58, n.º 3 (1 de março de 1985): 1031–33. http://dx.doi.org/10.1152/jappl.1985.58.3.1031.

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An automatic apparatus for the continuous measurement of O2 consumption of small laboratory animals is described. By use of a high-sensitivity pressure transducer with associated circuitry together with a peristaltic O2 delivery system, the closed respirometer chamber is maintained at atmospheric pressure +/- 0.5 mmH2O. O2 delivery is measured to within 0.25 ml by recording rotations of the peristaltic pump, following calibration by the withdrawal of a preset volume of air from the chamber. Static trials (with the chamber empty) indicate a high degree of reproducibility of data with the chamber pressure remaining at atmospheric pressure +/- 0.5 mmH2O as a result of the proportional, as opposed to fixed-volume, delivery of O2. Trials with mice and rats have likewise produced data with a high degree of reproducibility.

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Rostain, J. C., M. C. Gardette-Chauffour e R. Naquet. "Occurrence of high-pressure nervous syndrome at constant pressure during change of mixture". Journal of Applied Physiology 63, n.º 5 (1 de novembro de 1987): 1919–25. http://dx.doi.org/10.1152/jappl.1987.63.5.1919.

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Three professional divers have performed a dive to 450 msw. From 200 msw and during the first 64 h on the bottom, they breathed a H2-He-O2 mixture with 54–56% H2. At this time a switch was performed to a mixture with 30% H2, and 8 h later a second switch was performed to 0% H2. In the H2-He-O2 mixture the clinical symptoms of high-pressure nervous syndrome (HPNS) were not present and the electroencephalogram changes were slight. The switch of the mixture induced an isobaric HPNS of high intensity. Twenty-four hours later the HPNS decreased, but the clinical symptoms persisted throughout the stay in the He-O2 mixture. The appearance of isobaric HPNS during the switch might be due to the disappearance of the narcotic substance which suppressed or masked the clinical symptoms; it might also be due to the sudden increase in the partial pressure of He, which was equivalent to a fast compression.

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Loubeyre, Paul, e René LeToullec. "Stability of O2/H2 mixtures at high pressure". Nature 378, n.º 6552 (novembro de 1995): 44–46. http://dx.doi.org/10.1038/378044a0.

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9

Mills, S. J., e F. Nestola. "Elasticity and high-pressure structure of arsenoflorencite-(La): insights into the high-pressure behaviour of the alunite supergroup". Mineralogical Magazine 76, n.º 4 (agosto de 2012): 975–85. http://dx.doi.org/10.1180/minmag.2012.076.4.13.

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AbstractArsenoflorencite-(La), ideally LaAl3(AsO4)2(OH)6, was studied at high pressure by single-crystal X-ray diffractometry. The unit cell was determined at nine pressures up to 7.471(8) GPa; no evidence of a phase transformation was found in this range. The pressure volume data (refined simultaneously) were fitted to a third-order Birch Murnaghan equation of state which gave V0 = 710.71(8) Å3, KT0 = 106(2) GPa and K' = 9.2(9). These values were confirmed independently from an FE–fE plot. The crystal structure was refined at 1.596, 3.622, 5.749 and 7.471 GPa, the first time this has been done for a member the alunite supergroup. The compressibility of arsenoflorencite-(La) is strongly anisotropic, with βc > βa. The main compression mechanism was found to be governed by the internal angle O3 La O2 of the La polyhedron, where the O2 and O3 atoms move toward the c axis during compression.

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10

Lundegaard, Lars F., Christophe Guillaume, Malcolm I. McMahon, Eugene Gregoryanz e Marco Merlini. "On the structure of high-pressure high-temperature η-O2". Journal of Chemical Physics 130, n.º 16 (28 de abril de 2009): 164516. http://dx.doi.org/10.1063/1.3118970.

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Obrenovitch, T. P., e J. L. Gillard. "Decreased brain levels of ascorbic acid in rats exposed to high pressures". Journal of Applied Physiology 58, n.º 3 (1 de março de 1985): 839–43. http://dx.doi.org/10.1152/jappl.1985.58.3.839.

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Ascorbic acid was repeatedly monitored in vivo in the striatum of rats subjected to an increasing pressure (100 bar/h compression rate; 0.5 bar partial pressure of O2 He-O2 mixture, up to 120 bar (121 ATA), to which they were exposed for 1 h. Measurements were performed using differential pulse voltammetry and carbon fiber microelectrodes. High-pressure-exposed animals exhibited a dramatic decrease of striatal ascorbic acid. This decrease was detectable at pressures as low as 50 bar and significant over 70 bar (75% of the control level), and the lower level (25% of the control level) was reached shortly after the end of the compression period. This finding is discussed in relation to the physiological role of ascorbic acid in the brain, e.g., its participation in the defense mechanisms against reactive O2 intermediates and lipid peroxidations and its probable involvement in neurotransmission. Emphasis is placed on a possible increased sensitivity of nerve cell membrane phospholipids to peroxidation under stressful hyperbaric situations.

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12

Babaeva, Natalia Y., Ramesh Arakoni e Mark J. Kushner. "O2(Δ1) production in high pressure flowing He∕O2 plasmas: Scaling and quenching". Journal of Applied Physics 101, n.º 12 (15 de junho de 2007): 123306. http://dx.doi.org/10.1063/1.2743878.

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Reeves, J. T., B. M. Groves, J. R. Sutton, P. D. Wagner, A. Cymerman, M. K. Malconian, P. B. Rock, P. M. Young e C. S. Houston. "Operation Everest II: preservation of cardiac function at extreme altitude". Journal of Applied Physiology 63, n.º 2 (1 de agosto de 1987): 531–39. http://dx.doi.org/10.1152/jappl.1987.63.2.531.

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Hypoxia at high altitude could depress cardiac function and decrease exercise capacity. If so, impaired cardiac function should occur with the extreme, chronic hypoxemia of the 40-day simulated climb of Mt. Everest (8,840 m, barometric pressure of 240 Torr, inspiratory O2 pressure of 43 Torr). In the five of eight subjects having resting and exercise measurements at the barometric pressures of 760 Torr (sea level), 347 Torr (6,100 m), 282 Torr (7,620 m), and 240 Torr, heart rate for a given O2 uptake was higher with more severe hypoxia. Slight (6 beats/min) slowing of the heart rate occurred only during exercise at the lowest barometric pressure when arterial blood O2 saturations were less than 50%. O2 breathing reversed hypoxemia but never increased heart rate, suggesting that hypoxic depression of rate, if present, was slight. For a given O2 uptake, cardiac output was maintained. The decrease in stroke volume appeared to reflect decreased ventricular filling (i.e., decreased right atrial and wedge pressures). O2 breathing did not increase stroke volume for a given filling pressure. We concluded that extreme, chronic hypoxemia caused little or no impairment of cardiac rate and pump functions.

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Groves, B. M., J. T. Reeves, J. R. Sutton, P. D. Wagner, A. Cymerman, M. K. Malconian, P. B. Rock, P. M. Young e C. S. Houston. "Operation Everest II: elevated high-altitude pulmonary resistance unresponsive to oxygen". Journal of Applied Physiology 63, n.º 2 (1 de agosto de 1987): 521–30. http://dx.doi.org/10.1152/jappl.1987.63.2.521.

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High altitude increases pulmonary arterial pressure (PAP), but no measurements have been made in humans above 4,500 m. Eight male athletic volunteers were decompressed in a hypobaric chamber for 40 days to a barometric pressure (PB) of 240 Torr, equivalent to the summit of Mt. Everest. Serial hemodynamic measurements were made at PB 760 (sea level), 347 (6,100 m), and 282/240 Torr (7,620/8,840 m). Resting PAP and pulmonary vascular resistance (PVR) increased from sea level to maximal values at PB 282 Torr from 15 +/- 0.9 to 34 +/- 3.0 mmHg and from 1.2 +/- 0.1 to 4.3 +/- 0.3 mmHg.l–1 X min, respectively. During near maximal exercise PAP increased from 33 +/- 1 mmHg at sea level to 54 +/- 2 mmHg at PB 282 Torr. Right atrial and wedge pressures were not increased with altitude. Acute 100% O2 breathing lowered cardiac output and PAP but not PVR. Systemic arterial pressure and resistance did not rise with altitude but did increase with O2 breathing, indicating systemic control differed from the lung circulation. We concluded that severe chronic hypoxia caused elevated pulmonary resistance not accompanied by right heart failure nor immediately reversed by O2 breathing.

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Yamada, Y., A. Ito, K. Kuono, H. Yoshida e Y. Kobayashi. "Laser deposition of iron in oxygen atmosphere". Proceedings in Radiochemistry 1, n.º 1 (1 de setembro de 2011): 429–33. http://dx.doi.org/10.1524/rcpr.2011.0078.

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AbstractIron oxide films were produced by pulsed laser deposition (PLD) of 57Fe metal in an oxygen atmosphere and their compositions were studied by Mössbauer spectroscopy. The effects of gas-phase reactions were investigated by varying the pressure of O2 gas or an O2/Ar gas mixture. When PLD was performed in a high-pressure O2 atmosphere, the main product in the film was trivalent iron oxide particles. When the O2 pressure was reduced, hematite Fe2O3 became dominant in the film, while wüstite FeO was produced at very low O2 pressures. PLD in an O2/Ar gas mixture produced films of trivalent iron oxide particles and hematite solid, but wüstite was not produced. Increasing the substrate temperature during deposition induced annealing of the films, reducing the lattice defect density. X-ray diffraction patterns were obtained to confirm the assignments, and the surface morphologies of the films were investigated by scanning electron microscopy.

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Petracek, Peter D., D. Frank Kelsey e Craig Davis. "Response of Citrus Fruit to High-pressure Washing". Journal of the American Society for Horticultural Science 123, n.º 4 (julho de 1998): 661–67. http://dx.doi.org/10.21273/jashs.123.4.661.

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The effect of high-pressure washing (HPW) on the surface morphology and physiology of citrus fruit was examined. Mature white (Citrus paradisi Macf. `Marsh') and red (Citrus paradisi Macf. `Ruby Red') grapefruit, oranges (Citrus sinensis L. `Hamlin'), and tangelos (Citrus reticulata Blanco × Citrus paradisi Macf. `Orlando') were washed on a roller brush bed and under a water spraying system for which water pressure was varied. Washing white grapefruit and oranges for 10 seconds under conventional low water pressure (345 kPa at cone nozzle) had little effect on peel wax fine structure. Washing fruit for 10 seconds under high water pressure (1380 or 2760 kPa at veejet nozzle) removed most epicuticular wax platelets from the surface as well as other surface debris such as sand grains. Despite the removal of epicuticular wax, HPW did not affect whole fruit mass loss or exchange of water, O2, or CO2 at the midsection of the fruit. Analysis of the effect of nozzle pressure (345, 1380, or 2760 kPa), period of exposure (10 or 60 seconds), and wax application on internal gas concentrations 18 hours after washing showed that increasing nozzle pressure increased internal CO2 concentrations while waxing increased internal ethylene and CO2 concentrations and decreased O2 concentrations. An apparent wound ethylene response was often elicited from fruit washed under high pressures (≥2070 kPa) or for long exposure times (≥30 seconds).

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Burke, Michael P., Marcos Chaos, Yiguang Ju, Frederick L. Dryer e Stephen J. Klippenstein. "Comprehensive H2 /O2 kinetic model for high-pressure combustion". International Journal of Chemical Kinetics 44, n.º 7 (6 de dezembro de 2011): 444–74. http://dx.doi.org/10.1002/kin.20603.

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Lin, Xueqiang, Wei Liu, Fei Wu, Chuanchuan Xu, Juanjuan Dou e Minxu Lu. "Effect of O2 on corrosion of 3Cr steel in high temperature and high pressure CO2–O2 environment". Applied Surface Science 329 (fevereiro de 2015): 104–15. http://dx.doi.org/10.1016/j.apsusc.2014.12.109.

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Petracek, Peter D., e D. Frank Kelsey. "Physiological Responses of Citrus to High-pressure Washing". HortScience 30, n.º 4 (julho de 1995): 804C—804. http://dx.doi.org/10.21273/hortsci.30.4.804c.

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High-pressure washing (>689 to 3446 kPa or 100 to 500 psi at the spray nozzle) has been used recently in citrus packinghouses to improve the action of surfactant solution and brushing on the removal of dirt and superficial molds. Although high-pressure washing has no obvious detrimental effect on citrus fruit (e.g., no cellular breakage), its effects on physiology have not been fully examined. In this study gas samples were taken from the fruit core of `Orlando' tangelos, `Hamlin' oranges, and `Ruby Red' and white `Marsh' grapefruit prior to and following washing. An apparent wound ethylene response was measured for all varieties and was a function of prolonged exposure (>20 s) and excessive pressure (>2067 kPa). For the responding fruit, internal ethylene was initially detected about 3 h after washing, reached a maximum around 24 h (range: 0.1 to 0.6 ppm), and diminished to near background levels (0.0 ppm) after 48 h. No wound ethylene was observed when fruit were washed for the recommended exposure time (10 s) and pressure (1379 kPa). Concurrent decreases in internal O2 and increases in CO2 were observed for white and red grapefruit. High-pressure washing (1379 or 2757 kPa) did not affect water loss and water, O2, and CO2 exchange. The effects of subsequent waxing of the fruit (increased internal ethylene and CO2 levels and reduced of internal O2 levels) were amplified by washing at the higher pressure (2757 kPa).

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Fujiwara, Atsushi, Naoyuki Hatayama, Natsumi Matsuura, Naoya Yokota, Kaori Fukushige, Tomiko Yakura, Shintaro Tarumi et al. "High-Pressure Carbon Monoxide and Oxygen Mixture is Effective for Lung Preservation". International Journal of Molecular Sciences 20, n.º 11 (3 de junho de 2019): 2719. http://dx.doi.org/10.3390/ijms20112719.

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(1) Background: Heme oxygenase-1 (HO-1) degrades heme and generates carbon monoxide (CO), producing various anti-inflammatory, anti-oxidative, and anti-apoptotic effects. This study aimed to confirm the effects of CO on the ischemia–reperfusion injury (IRI) of donor lungs using a high-pressure gas (HPG) preservation method. (2) Methods: Donor rat and canine lungs were preserved in a chamber filled with CO (1.5 atm) and oxygen (O2; 2 atm) and were ventilated with either CO and O2 mixture (CO/O2 group) or air (air group) immediately before storage. Rat lungs were subjected to heterotopic cervical transplantation and evaluated after reperfusion, whereas canine lungs were subjected to allogeneic transplantation and evaluated. (3) Results: Alveolar hemorrhage in the CO/O2 group was significantly milder than that in the air group. mRNA expression levels of HO-1 remained unchanged in both the groups; however, inflammatory mediator levels were significantly lower in the CO/O2 group than in the air group. The oxygenation of graft lungs was comparable between the two groups, but lactic acid level tended to be higher in the air group. (4) Conclusions: The HO-1/CO system in the HPG preservation method is effective in suppressing IRI and preserving donor lungs.

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Norins, Nan A., Karen Wendelberger, Raymond G. Hoffman, Peter A. Keller e Jane A. Madden. "Effects of Indomethacin on Myogenic Contractile Activation and Responses to Changes in O2 and CO2 in Isolated Feline Cerebral Arteries". Journal of Cerebral Blood Flow & Metabolism 12, n.º 5 (setembro de 1992): 866–72. http://dx.doi.org/10.1038/jcbfm.1992.118.

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We used an isolated, pressurized, and perfused feline middle cerebral artery preparation to measure how changes in intraluminal pressure and alterations in O2 and CO2 affect vessel diameter and myogenic contractile activation before and after treatment with indomethacin (IND). Vessel diameters were measured over the pressure range 60–140 mm Hg. The arteries were then exposed to low O2 (50 torr) and/or high CO2 (65 torr) and diameters remeasured over the same range. Under control conditions, the arteries exhibited myogenic contractile activation. Exposure to low O2, high CO2, or a mixture of low O2/high CO2, increased vessel diameter but did not change the vessels' myogenic contractile responsiveness to changes in pressure. Arteries exposed to IND decreased in diameter but retained myogenic contractile activity. In the presence of IND, vessels dilated to both low O2 and a mixture of low O2/high CO2, but did not dilate to high CO2 alone. Under all conditions, vessels retained myogenic contractile activity. Results obtained under control conditions and low O2 confirm those of others using similar systems. Myogenic contractile activity in the presence of high CO2 or a mixture of low O2/high CO2 has not been previously reported. The dilation to low O2 but not to high CO2 in the presence of IND suggests that this drug's effects in cerebral arteries are not limited solely to inhibition of prostaglandin synthesis.

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Qu, Lina, Zhenzhen Wang e Long Liu. "Molecular Simulation Study Based on Adsorption of Gas (CO2,O2,CH4) on Coal". Fire 6, n.º 9 (11 de setembro de 2023): 355. http://dx.doi.org/10.3390/fire6090355.

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This study aimed to further explore the adsorption properties of different gases (CO2, O2, and CH4) on the coking coal surface by establishing a molecular model. Changes in the absolute adsorption capacity and the isosteric heat of adsorption of gases under different temperatures, pressures, and compositions were simulated using grand canonical Monte Carlo (GCMC) and molecular dynamics simulations. Interaction energy and energy distribution were used to analyze the adsorption behavior of gases, and the diffusion properties were investigated using the diffusion coefficient and diffusion activation energy. The absolute adsorption results fit well with the Langmuir–Freundlich model. The absolute adsorption capacity had a significant positive correlation with pressure and the corresponding mole fraction, and a significant negative correlation with temperature. The competitiveness, based on binary adsorption selectivity, was in the order of CO2 > O2 > CH4. The isosteric heat of adsorption of CH4 was slightly higher than that of O2, and that of CO2 was 1.49–1.64 times that of O2 and CH4. The isosteric heat of the adsorption of gases was also barely influenced by temperature and pressure. The interaction energy between CO2 and coal was greater than that of O2 or CH4, but the high pressure and high content were not conducive to the adsorption of O2 by CO2. The preferred adsorption site for CO2 was stronger than that for O2 and CH4, and its peak value negatively correlated with the molar fraction. The diffusion coefficient for single component gases initially increased and then decreased with increased pressure, showing a positive correlation with temperature. A close inverse correlation existed between diffusion activation energy and pressure. These results revealed the microscopic adsorption and diffusion regularities of CO2, O2, and CH4 in the coal model, indicating great significance in accurately predicting coal fires.

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Brauer, R. W., J. A. Dutcher, W. Hinson e W. S. Vorus. "Prolonged exposure of mice to He-O2 at high pressure: effects on seizure and anesthesia liability". Journal of Applied Physiology 61, n.º 6 (1 de dezembro de 1986): 2005–11. http://dx.doi.org/10.1152/jappl.1986.61.6.2005.

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Multiday exposures of CD-1 mice to He-O2 atmospheres at pressures from 30 to 100 atm result in marked increases of threshold pressures for type I high-pressure neurological syndrome seizures. The effect develops with a half time (t1/2) of 12 h and is reversible (t1/2 = 7 h). The maximum enhancement of Pc is attained at a conditioning pressure of 80 ATA. Pressure conditioning also results in suppression of the compression rate effect on Pc. Furthermore, reserpine blocks the increase in Pc during prolonged pressure exposure. The entire effect thus appears to be an extension in time of the monoaminergic compression rate effect on Pc. Pressure conditioning does not modify anesthesia tolerance, unlike N2 habituation which affects anesthesia threshold pressure as well as Pc. The results are compared with the effects of habituation to inert-gas narcotics and the implications of the data for an understanding of inert-gas high-pressure antagonism in intact animals are discussed.

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Beaudry, Randolph M. "EFFECT OF ELEVATED CARBON DIOXIDE LEVELS ON BLUEBERRY FRUIT RESPIRATION AND RESPIRATORY QUOTIENT". HortScience 27, n.º 6 (junho de 1992): 676f—676. http://dx.doi.org/10.21273/hortsci.27.6.676f.

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Blueberry fruit were sealed in 0.00254 cm (1 mil) thick, 200 cm2 low density polyethylene pouches, which, in turn, were sealed in containers continually purged with gas mixtures containing 0, 20, 40 or 60 kPa CO2 and held at 15C. Sampling the gas composition of the enclosed package permitted accurate determination of O2 uptake, CO2 production and the respiratory quotient (RQ) despite the high background CO2 levels. O2 uptake was minimally affected by the CO2 treatments. CO2 production, however, increased at CO2 partial pressures over 20 kPa, resulting in an elevated RQ at 40 and 60 kPa CO2. Raising the CO2 partial pressure caused the fruit to become more sensitive to lowered O2, raising the O2 partial pressure associated with the RQ breakpoint.

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Cowman, J., C. I. Torres e B. E. Rittmann. "Total nitrogen removal in an aerobic/anoxic membrane biofilm reactor system". Water Science and Technology 52, n.º 7 (1 de outubro de 2005): 115–20. http://dx.doi.org/10.2166/wst.2005.0189.

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The hydrogen-based membrane biofilm reactor (MBfR) is effective for reducing nitrate-N to N2 gas, but most wastewaters contain ammonium-N. Here, we document that an aerobic/anoxic MBfR system achieves nearly total N removal (<2 mgN/L) when the influent N is ammonium. The aerobic/anoxic MBfR couples two MBfR modules. The aerobic MBfR is supplied O2 and brings about nitrification of ammonium to nitrate or nitrite. The anoxic MBfR is supplied H2 and brings about denitrification to N2 gas. Total N removal is most strongly influenced by the O2 pressure in the aerobic module: too low O2 caused poor nitrification, while too high O2 inhibited denitrification in the anoxic module. Hydrogen pressure does not strongly affect total-N removal, and the best total-N removal occurs when the H2 and O2 pressures are similar.

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Peng Qingjun, 彭庆军, 司马文霞 Sima Wenxia, 杨庆 Yang Qing, 袁涛 Yuan Tao, 刘兴华 Liu Xinghua, 邹立峰 Zou Lifeng e 李玉森 Li Yusen. "Simulation of capacitively coupled high-pressure glow discharge in He-O2". High Power Laser and Particle Beams 24, n.º 12 (2012): 2841–47. http://dx.doi.org/10.3788/hplpb20122412.2841.

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Malyshenko, S. "High-pressure H2/O2-steam generators and their possible applications". International Journal of Hydrogen Energy 29, n.º 6 (maio de 2004): 589–96. http://dx.doi.org/10.1016/j.ijhydene.2003.08.004.

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Akashi, T., Miho Kasajima, Chiharu Muraoka e Hajime Kiyono. "High Temperature Oxidation of SiC Powder in Oxidizing Atmosphere Containing Water Vapor". Key Engineering Materials 403 (dezembro de 2008): 197–200. http://dx.doi.org/10.4028/www.scientific.net/kem.403.197.

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Oxidation of SiC powder was studied at 1373 K to 1873 K in Ar-O2, Ar-H2O, and Ar-O2-H2O using thermogravimetry. At 1373 K to 1573K, the weight gain increased with increasing water vapor pressure. The oxidation rate was evaluated on the basis of the Ginstering-Brounshtein kinetic model. In this temperature region, the apparent activation energy for the oxidation was almost the same (139-191 kJmol-1) independent of the atmosphere, suggesting that the same oxidation process proceeds. On the other hand, at temperatures >1673 K, the weight gain in the dry O2 (Ar-O2) was greater than that in the wet and wet O2 (Ar-H2O and Ar-O2-H2O). The apparent activation energy in the dry O2 (442 kJmol-1) was much greater than that in the wet and wet O2. We propose that water molecule diffused in silica layer in the wet and wet O2 atmosphere at 1373 K to 1873 K.

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Groves, B. M., T. Droma, J. R. Sutton, R. G. McCullough, R. E. McCullough, J. Zhuang, G. Rapmund, S. Sun, C. Janes e L. G. Moore. "Minimal hypoxic pulmonary hypertension in normal Tibetans at 3,658 m". Journal of Applied Physiology 74, n.º 1 (1 de janeiro de 1993): 312–18. http://dx.doi.org/10.1152/jappl.1993.74.1.312.

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Elevated pulmonary arterial pressure in high-altitude residents may be a maladaptive response to chronic hypoxia. If so, well-adapted populations would be expected to have pulmonary arterial pressures that are similar to sea-level values. Five normal male 22-yr-old lifelong residents of > or = 3,600 m who were of Tibetan descent were studied in Lhasa (3,658 m) at rest and during near-maximal upright ergometer exercise. We found that resting mean pulmonary arterial pressure [15 +/- 1 (SE) mmHg] and pulmonary vascular resistance (1.8 +/- 0.2 Wood units) were within sea-level norms and were little changed while subjects breathed a hypoxic gas mixture [arterial O2 pressure (PaO2) = 36 +/- 2 Torr]. Near-maximal exercise [87 +/- 13% maximal O2 uptake (VO2max)] increased cardiac output more than threefold to values of 18.3 +/- 1.2 l/min but did not elevate pulmonary vascular resistance. Breathing 100% O2 during near-maximal exercise did not reduce pulmonary arterial pressure or vascular resistance. We concluded that this small sample of healthy Tibetans with lifelong residence > or = 3,658 m had resting pulmonary arterial pressures that were normal by sea-level standards and exhibited minimal hypoxic pulmonary vasoconstriction, both at rest and during exercise. These findings are consistent with remarkable cardiac performance and high-altitude adaptation.

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Samaja, Michele, Sonia Allibardi, Giuseppina Milano, Gabriella Neri, Bruno Grassi, L. Bruce Gladden e Michael C. Hogan. "Differential depression of myocardial function and metabolism by lactate and H+". American Journal of Physiology-Heart and Circulatory Physiology 276, n.º 1 (1 de janeiro de 1999): H3—H8. http://dx.doi.org/10.1152/ajpheart.1999.276.1.h3.

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The effects of both high blood H+ concentration ([H+]) and high blood lactate concentration ([lactate]) under ischemia-reperfusion conditions are receiving attention, but little is known about their effects in nonischemic hearts. Isolated rat hearts were Langendorff perfused at constant flow with media at two pH values (7.4 and 7.0) and two [lactate] (0 and 20 mM) in various sequences ( n = 6/group). Coronary flow and arterial O2content were kept constant at levels that allowed hearts to function without O2 supply limitation. We measured contractility, O2 uptake, diastolic pressure, and at the end of the protocol, tissue [lactate] and pH. Perfusion with high [lactate] raised tissue [lactate] from 5.5 ± 0.1 to 17.5 ± 2.6 μmol/heart ( P < 0.0001), whereas decreasing the pH of the medium decreased tissue pH from 6.94 ± 0.02 to 6.81 ± 0.06 ( P = 0.002). Heart rate was not affected by high [lactate] but was reversibly depressed by high [H+] ( P = 0.004). Developed pressure declined by 20% in response to high [lactate], high [H+], and high [lactate] + high [H+] ( P = 0.002). After the high-[lactate] challenge was withdrawn, pressure continued to decline. In contrast, withdrawing the high [H+] challenge allowed partial recovery. The behavior of diastolic pressure mirrored that of developed pressure. Although unaffected by high [lactate], the O2 uptake was reversibly depressed by high [H+]. This suggests higher O2 cost per contraction in the presence of high [lactate]. We conclude that for similar acute contractility depression, high [lactate] induces irreversible damage, likely at some point in the pathway of O2 utilization. In contrast, the effect of high [H+] appears reversible. These differential behaviors may have implications for heart function during heavy exercise and ischemia-reperfusion events.

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Lafumat, Bénédicte, Christoph Mueller-Dieckmann, Gordon Leonard, Nathalie Colloc'h, Thierry Prangé, Thierry Giraud, Fabien Dobias, Antoine Royant, Peter van der Linden e Philippe Carpentier. "Gas-sensitive biological crystals processed in pressurized oxygen and krypton atmospheres: deciphering gas channels in proteins using a novel `soak-and-freeze' methodology". Journal of Applied Crystallography 49, n.º 5 (16 de agosto de 2016): 1478–87. http://dx.doi.org/10.1107/s1600576716010992.

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Molecular oxygen (O2) is a key player in many fundamental biological processes. However, the combination of the labile nature and poor affinity of O2 often makes this substrate difficult to introduce into crystals at sufficient concentrations to enable protein/O2 interactions to be deciphered in sufficient detail. To overcome this problem, a gas pressure cell has been developed specifically for the `soak-and-freeze' preparation of crystals of O2-dependent biological molecules. The `soak-and-freeze' method uses high pressure to introduce oxygen molecules or krypton atoms (O2 mimics) into crystals which, still under high pressure, are then cryocooled for X-ray data collection. Here, a proof of principle of the gas pressure cell and the methodology developed is demonstrated with crystals of enzymes (lysozyme, thermolysin and urate oxidase) that are known to absorb and bind molecular oxygen and/or krypton. The successful results of these experiments lead to the suggestion that the soak-and-freeze method could be extended to studies involving a wide range of gases of biological, medical and/or environmental interest, including carbon monoxide, ethylene, methane and many others.

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Jacobson, Azita, Changdong Yan, Qun Gao, Tibisay Rincon-Skinner, Aracelie Rivera, John Edwards, An Huang, Gabor Kaley e Dong Sun. "Aging enhances pressure-induced arterial superoxide formation". American Journal of Physiology-Heart and Circulatory Physiology 293, n.º 3 (setembro de 2007): H1344—H1350. http://dx.doi.org/10.1152/ajpheart.00413.2007.

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The purpose of this study was to investigate the mechanisms that regulate superoxide (O2•−) production as a function of an acute elevation of intravascular pressure and age. Mesenteric arteries isolated from young (6 mo) and aged (24 mo) male Fischer 344 rats were used. O2•− production in vessels in response to 80 (normal pressure, NP) and 180 (high pressure, HP) mmHg was determined by the superoxide dismutase-inhibitable nitroblue tetrazolium (NBT) reduction assay. In vessels exposed to NP, O2•− production was significantly higher in aged than in young vessels (32.7 ± 7.0 vs. 15.4 ± 2.4 nmol·mg−1·30 min−1). HP enhanced O2•− production in vessels of both groups, but the enhancement was significantly greater in aged than in young vessels (63.4 ± 6.7 vs. 32.7 ± 4.3 nmol·mg−1·30 min−1). Apocynin (100 μmol/l) attenuated HP-induced increases in O2•− production in both groups, whereas allopurinol (100 μmol/l) and Nω-nitro-l-arginine methyl ester (100 μmol/l) inhibited the response only in aged vessels. Confocal microscopy showed increases in O2•− in response to HP in endothelial and smooth muscle layers of both groups, with much greater fluorescent staining in aged than in young rats and in the endothelium than in smooth muscle cells. No significant changes in NAD(P)H oxidase gene and protein expressions were observed in vessels of the two groups. Upregulation of protein expression of xanthine oxidase was detected in aged vessels. We conclude that NAD(P)H oxidase contributes importantly to HP-induced enhanced O2•− production in vessels of both young and aged rats, whereas xanthine oxidase and nitric oxide synthase-dependent O2•− production also contribute to the enhancement in mesenteric arteries of aged rats.

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Li, Jun, Raheel Ahmed e Xiaochun Li. "Thermodynamic Modeling of CO2-N2-O2-Brine-Carbonates in Conditions from Surface to High Temperature and Pressure". Energies 11, n.º 10 (1 de outubro de 2018): 2627. http://dx.doi.org/10.3390/en11102627.

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Nitrogen (N2) and oxygen (O2) are important impurities obtained from carbon dioxide (CO2) capture procedures. Thermodynamic modeling of CO2-N2-O2-brine-minerals is important work for understanding the geochemical change of CO2 geologic storage with impurities. In this work, a thermodynamic model of the CO2-N2-O2-brine-carbonate system is established using the “fugacity-activity” method, i.e., gas fugacity coefficients are calculated using a cubic model and activity coefficients are calculated using the Pitzer model. The model can calculate the properties at an equilibrium state of the CO2-N2-O2-brine-carbonate system in terms of gas solubilities, mineral solubilities, H2O solubility in gas-rich phase, species concentrations in each phase, pH and alkalinity. The experimental data of this system can be well reproduced by the presented model, as validated by careful comparisons in conditions from surface to high temperature and pressure. The model established in this work is suitable for CO2 geologic storage simulation with N2 or O2 present as impurities.

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Jin, Zhao, Jing Liu e Yichao Ma. "Explosible Oxygen Concentration and Lower Explosion Limit of RP-3 Aviation Kerosene Vapor/O₂/N₂ Mixtures at Elevated Pressure and High temperature". Journal of Physics: Conference Series 2569, n.º 1 (1 de agosto de 2023): 012024. http://dx.doi.org/10.1088/1742-6596/2569/1/012024.

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Abstract RP-3 aviation kerosene is widely used in China, and the critical explosible oxygen concentration (COC) and lower explosion limit (LEL) are important parameters concerned about aviation safety. The COC and LEL characteristics of RP-3 aviation kerosene vapor/O2/N2 mixtures at different initial temperatures and pressure were investigated experimentally. The LEL for RP-3 vapor/O2/N2 mixtures ranges from 0.5 vol% to 0.6 vol%, with the ambient pressure ranging from 40 kPa to 100 kPa, temperature from 60°C to 150°C, which is almost unchanged. The COC decreases as the temperature and pressure increase, and the COC of RP-3 vapor/O2/N2 mixtures is 9.7 vol% under the pressure of 100 kPa and 150°C. The suppression performance of N2 on the RP-3 vapor/O2/N2 mixtures was discussed, and the suppression performance model was defined in this paper, the suppression performance on COC condition is about 77%.

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Khedekar, Kaustubh, Christopher Evan Van Pelt, Ryan Gebhardt, Iryna V. Zenyuk, Guido Bender, Rangachary Mukundan, Andrew M. Park, Rod L. Borup e Siddharth Komini Babu. "Understanding Gas Permeation during High Pressure Operation of PEM Water Electrolyzers". ECS Meeting Abstracts MA2022-02, n.º 44 (9 de outubro de 2022): 1662. http://dx.doi.org/10.1149/ma2022-02441662mtgabs.

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Governments and industries across the world have initiated implementation of clean hydrogen (H2) to achieve zero emissions, yet significant challenges remain for large scale adoption. With the decreasing renewable electricity cost PEM water electrolyzers (PEMWEs) show significant potential for at scale deployment due to their high faradaic efficiency and high operating current density. To reduce the per kilogram price of hydrogen and increase the overall energy efficiency, PEMWEs need to be operated at high differential pressures (30 to 50 bar) to eliminate the need for compression during storage and transportation1. To achieve high faradaic efficiency, thinner membranes are required to reduce voltage losses within the cell. However, thinner membranes exhibit a higher gas permeation rate which leads to increased crossover of hydrogen from the cathode through the membrane to the anode. Such increased crossover of H2 not only reduces the efficiency but can also result in flammable gas mixtures (lower flammability limit for H2 in O2 is 4 %) as Iridium/Iridium oxide (anode catalyst) is inefficient in oxidizing H2 1. The addition of a gas recombination catalyst (GRC) to the membrane is an useful strategy to oxidize permeating H2 and minimize the H2:O2 ratio at the anode. In this study, a high pressure (up to 30 bar) electrolyzer setup is coupled with online gas chromatography-mass spectrometry to understand the H2 gas permeation in membranes as a function of H2 partial pressure and operating current density (simulated by varying the flow rates) as shown in Figure 1 . Effect of the GRC, its loading, and its location on the H2 permeation will be elucidated. Differences induced by the addition of anode and cathode catalyst layers on H2 permeation rates will also be presented. Figure 1. Ex-situ H2 permeation rate at different cathode operating pressure at 80 °C. The anode was maintained at 1 bar of O2 partial pressure Acknowledgement This research is supported by the U.S. Department of Energy (DOE) through the Hydrogen and Fuel Cell Technologies Office, program manager Dave Peterson Reference Bernt, M., Schröter, J., Möckl, M. & Gasteiger, H. A. Analysis of Gas Permeation Phenomena in a PEM Water Electrolyzer Operated at High Pressure and High Current Density. J. Electrochem. Soc. 167, 124502 (2020). Figure 1

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Zagidullin, M. V., N. V. Erasov, A. Yu Kurov, V. D. Nikolaev, M. I. Svistun e N. A. Khvatov. "An oxygen–iodine laser utilizing a high-pressure O2(1Δ) generator". Soviet Journal of Quantum Electronics 21, n.º 12 (31 de dezembro de 1991): 1303–4. http://dx.doi.org/10.1070/qe1991v021n12abeh004527.

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Grosso Ferreira, R., B. Carvalho, J. Rodrigues, R. Rodrigues, A. Smith, L. Marraffa e M. Lino da Silva. "Unfocused laser ignition of high-pressure He–H2-O2 combustible mixtures". International Journal of Hydrogen Energy 58 (março de 2024): 948–53. http://dx.doi.org/10.1016/j.ijhydene.2024.01.271.

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Piliai, Lesia, David Tomeček, Martin Hruška, Ivan Khalakhan, Jaroslava Nováková, Přemysl Fitl, Roman Yatskiv et al. "New Insights towards High-Temperature Ethanol-Sensing Mechanism of ZnO-Based Chemiresistors". Sensors 20, n.º 19 (30 de setembro de 2020): 5602. http://dx.doi.org/10.3390/s20195602.

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In this work, we investigate ethanol (EtOH)-sensing mechanisms of a ZnO nanorod (NRs)-based chemiresistor using a near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS). First, the ZnO NRs-based sensor was constructed, showing good performance on interaction with 100 ppm of EtOH in the ambient air at 327 °C. Then, the same ZnO NRs film was investigated by NAP-XPS in the presence of 1 mbar oxygen, simulating the ambient air atmosphere and O2/EtOH mixture at the same temperature. The partial pressure of EtOH was 0.1 mbar, which corresponded to the partial pressure of 100 ppm of analytes in the ambient air. To better understand the EtOH-sensing mechanism, the NAP-XPS spectra were also studied on exposure to O2/EtOH/H2O and O2/MeCHO (MeCHO = acetaldehyde) mixtures. Our results revealed that the reaction of EtOH with chemisorbed oxygen on the surface of ZnO NRs follows the acetaldehyde pathway. It was also demonstrated that, during the sensing process, the surface becomes contaminated by different products of MeCHO decomposition, which decreases dc-sensor performance. However, the ac performance does not seem to be affected by this phenomenon.

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Sahin, Mazlum, Helin El e Ibrahim Akkoç. "Comparison of Mask Oxygen Therapy and High-Flow Oxygen Therapy after Cardiopulmonary Bypass in Obese Patients". Canadian Respiratory Journal 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/1039635.

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Background. To clarify the efficiency of mask O2 and high-flow O2 (HFO) treatments following cardiopulmonary bypass (CPB) in obese patients. Methods. During follow-up, oxygenization parameters including arterial pressure of oxygen (PaO2), peripheral oxygen saturation (SpO2), and arterial partial pressure of carbon dioxide (PaCO2) and physical examination parameters including respiratory rate, heart rate, and arterial pressure were recorded respectively. Presence of atelectasia and dyspnea was noted. Also, comfort scores of patients were evaluated. Results. Mean duration of hospital stay was 6.9 ± 1.1 days in the mask O2 group, whereas the duration was significantly shorter (6.5 ± 0.7 days) in the HFO group (p=0.034). The PaO2 values and SpO2 values were significantly higher, and PaCO2 values were significantly lower in patients who received HFO after 4th, 12th, 24th, 36th, and 48th hours. In postoperative course, HFO leads patients to achieve better postoperative FVC (p<0.001). Also, dyspnea scores and comfort scores were significantly better in patients who received HFO in both postoperative day 1 and day 2 (p<0.001,p<0.001 and p=0.002,p=0.001, resp.). Conclusion. Our study demonstrated that HFO following CPB in obese patients improved postoperative PaO2, SpO2, and PaCO2 values and decreased the atelectasis score, reintubation, and mortality rates when compared with mask O2.

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Dong, Zicheng, Aihan Feng, Hao Wang, Shoujiang Qu e Hao Wang. "Thermodynamic Study on Initial Oxidation Behavior of TiAl-Nb Alloys at High Temperature". Metals 13, n.º 3 (26 de fevereiro de 2023): 485. http://dx.doi.org/10.3390/met13030485.

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The initial oxidation behavior of TiAl-Nb alloys was systematically investigated against the composition, temperature, and partial pressure of O2 with the CALculation of PHAse Diagrams (CALPHAD) technique. The mole fraction of each oxidation product at the initial oxidation stage of the alloys at the corresponding temperatures was predicted. The initial oxidation products of the alloys are oxides of Al, Ti, and Nb, with the oxidation order of Al, Ti, and Nb. As P(O2) increases, the Ti and Nb oxidation products move towards a high oxygen content, and the mole fractions of the Al and Ti oxides gradually decrease and increase, respectively. It was found that the temperature and partial pressure of O2 determined the types of the oxides and the oxidation order, while the concentration of Nb and Al determined the mole fraction of the oxides. The CALPHAD results are in good agreement with the experiments.

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Cala, S. J., J. Edyvean, M. Rynn e L. A. Engel. "O2 cost of breathing: ventilatory vs. pressure loads". Journal of Applied Physiology 73, n.º 5 (1 de novembro de 1992): 1720–27. http://dx.doi.org/10.1152/jappl.1992.73.5.1720.

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We compared the O2 cost of breathing (VO2resp) at high levels of ventilation (HV) with that against high inspiratory pressure loads (HP) using an external elastance when end-expiratory volume, work rate (W), and pressure-time product (P) were matched at two levels of ventilation and elastic loading. Each of five normal subjects performed three pairs of loaded runs (one HV and one HP) bracketed by two resting runs. Mean O2 consumption from the pairs of resting runs was subtracted from that of each of the loaded runs to give VO2resp during loaded breathing. Matching for W and P was within 15% in all 15 pairs of runs. During HV runs, ventilation was 398 +/- 24% of corresponding values during HP runs (P < 0.01). Although there was no difference in W (P > 0.05), the VO2resp during HV runs was 237 +/- 33% of that during HP (P < 0.01) and efficiency of HV was 51 +/- 5% of that during HP (P < 0.01). When W was normalized for the decrease in maximum inspiratory pressure with increased mean lung volume, efficiency during HV and HP runs did not differ (P > 0.05). In the second series of experiments, when both HV and HP runs were matched for W but P was allowed to vary, efficiency increased by 1.42 +/- 0.42% (P < 0.05) for each percent decrease in P during HV runs but was unchanged (P > 0.05) during HP runs despite a 193 +/- 10% increase in P.(ABSTRACT TRUNCATED AT 250 WORDS)

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Gran, Christopher D., e Randolph M. Beaudry. "DETERMINATION OF LOW OXYGEN TOLERANCE LIMITS FOR SEVERAL APPLE CULTIVARS". HortScience 27, n.º 6 (junho de 1992): 592g—593. http://dx.doi.org/10.21273/hortsci.27.6.592g.

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The oxygen partial pressure associated with the respiratory quotient (RQ) breakpoint (ie., lower oxygen limit) was determined for fruits of several apple cultivars stored at 0°C. Fruits were sealed in low density polyethylene pouches of various thicknesses and known permeability to determine O2 uptake, CO2 production, and respiratory quotients (RQ) at various O2 partial pressures. There were differences in the shape of O2 uptake versus steady state O2 curves between cultivars. While some cultivars showed steady declines in respiration rate from 8 kPa O2 to < 1 kPa, other cultivars showed no decline in respiration until O2 levels fell below 3 to 4 kPa. Fruits having elevated RQ values had greater levels of headspace ethanol in the polyethylene pouches, which confirmed anaerobic respiration. The lower oxygen limit ranged from a low of approximately 0.75 kPa for cultivars Northern Spy and Law Rome to high of 1.5 kPa for McIntosh.

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Kuznetsov, A. Yu, L. Dubrovinsky, A. Kurnosov, M. M. Lucchese, W. Crichton e C. A. Achete. "High-Pressure Synthesis and Study of NO+NO3− and NO2+NO3− Ionic Solids". Advances in Physical Chemistry 2009 (4 de janeiro de 2009): 1–11. http://dx.doi.org/10.1155/2009/180784.

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Nitrosonium-nitrate NO+NO3− and dinitrogen pentoxide NO2+NO3− ionic crystals were synthesized by laser heating of a condensed oxygen-rich O2-N2 mixture compressed to different pressures, up to 40 GPa, in a diamond anvil cell (DAC). High-pressure/high-temperature Raman and X-ray diffraction studies of synthesized samples disclosed a transformation of NO+NO3− compound to NO2+NO3− crystal at temperatures above ambient and pressures below 9 GPa. High-pressure experiments revealed previously unreported bands in Raman spectra of NO+NO3− and NO2+NO3− ionic crystals. Structural properties of both ionic compounds are analyzed. Obtained experimental results support a hypothesis of a rotational disorder of NO+ complexes in NO+NO3− and indicate a rotational disorder of ionic complexes in NO2+NO3− solid.

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Guilloy, Kevin, Nicolas Pauc, Alban Gassenq e Vincent Calvo. "High aspect ratio germanium nanowires obtained by dry etching". MRS Advances 1, n.º 13 (2016): 875–80. http://dx.doi.org/10.1557/adv.2016.159.

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ABSTRACTWe present here a reactive ion etching recipe to fabricate germanium nanowires. We used a combination of Cl2, N2 and O2 and studied the influence of both the gas pressure and the O2 mass flow on the morphology of the nanowires. 5 µm long nanowires with an aspect ratio of 20 are demonstrated with smooth surfaces and a tapering below 20 nm/µm. We also show that both gold and aluminum can be used as hard mask; the latter achieving a selectivity with germanium above 100.

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Argo, William R., John A. Biernbaum e William C. Fonteno. "Root Medium Carbon Dioxide and Oxygen Partial Pressures for Container-grown Chrysanthemums". HortScience 31, n.º 3 (junho de 1996): 385–88. http://dx.doi.org/10.21273/hortsci.31.3.385.

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Medium CO2 and O2 partial pressures were measured at three locations [3.8 (top layer), 7.5 (middle layer), and 10.3 (bottom layer) cm below the rim] in 15-cm-tall pots containing flowering chrysanthemums [Dendranthem×grandiflorum (Ramat.) Kitamura] grown in one of three root media. Average ambient medium CO2 and O2 partial pressures were 63 Pa and 21 kPa, respectively, and were similar in the three sampled layers in root media with an average moisture content of 50% to 60% of container capacity. Within 10 minutes after a drip-irrigation application of well water containing a titratable alkalinity to pH 4.5 of 320 mg CaCO3/liter, the partial pressure of medium CO2 increased to ≤1600 Pa and medium O2 decreased to 20.5 kPa in the top and middle layers of the pot. With subirrigation, medium CO2 partial pressures increased to ≤170 Pa and medium O2 remained at 21 kPa. When reverse-osmosis purified water (titratable alkalinity to pH 4.5 of <20 mg CaCO3/liter) was used instead of well water, the large increase in medium CO2 did not occur, indicating that the bicarbonate alkalinity in the irrigation water was the source of CO2. The high medium CO2 partial pressure measured after irrigation was not persistent; within 180 minutes, it returned to levels averaging 45% higher (100 Pa) than that measured before the irrigation. Medium O2 also had returned to ambient levels 180 minutes after the irrigation.

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Grzesik, Z., e S. Mrowec. "High Temperature Corrosion of Metallic Materials in Composed Oxidizing Environments". High Temperature Materials and Processes 31, n.º 4-5 (30 de outubro de 2012): 539–51. http://dx.doi.org/10.1515/htmp-2012-0091.

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AbstractBasing on actual theoretical approach and experimental results, the mechanism of sulphide formation beneath the oxide scale grown on metals in SO2-O2 atmospheres has been described. It has been shown that in spite of much lower sulphur partial pressure in the oxidizing atmosphere than the dissociation pressure of the sulphide to be formed, the sulphidation process takes place beneath the oxide scale. This, at the first sight, unexpected behavior results from the fact that sulphur is diffusing inwards through the primary oxide scale in the molecular form, i.e. SO2 molecules. Reaching thus metal-scale interface, where the oxygen partial pressure is very low, virtually equal to the dissociation pressure of the oxide forming the scale, SO2 ⇔ O2 + ½S2 equilibrium is shifted to the right, as a result of which the partial pressure of sulphur vapor dramatically increases, reaching the value several orders of magnitude higher than that needed for sulphide formation.Analogous situation is observed during oxidation of chromium steels in CO2-O2 atmospheres. In this case, namely, carburisation process is observed beneath the oxide scale, in spite of the fact that carbon activity in this environment is several order of magnitude lower than that required for chromium carbide formation. This again unexpected situation becomes understandable if one assumes – like in the case of metal oxidation in SO2 containing atmosphere – that carbon is transported through the oxide scale in the form of CO2 molecules.The final conclusion is, that the explanation of the mechanism of sulphide formation beneath the oxide scale on metals and of carburization beneath the oxide scales on steels constitutes the important step forward, leading to the better understanding of high temperature corrosion mechanisms of metallic materials, observed in multicomponent agresive gases.

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Peterson, Sharon J., Werner J. Lipton e Masami Uota. "Methods for Premixing Gases in Pressurized Cylinders for Use in Controlled Atmosphere Experiments". HortScience 24, n.º 2 (abril de 1989): 328–31. http://dx.doi.org/10.21273/hortsci.24.2.328.

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Abstract Methods for mixing various concentrations of O2, CO2, N2, and C2H4 in high-pressure cylinders are described. The concentrations are mixed by partial pressure or partial volume and then are verified by gas chromatography. The procedures generally allow for a precision of ±5% when either 1.0% O2 or CO2 or higher concentrations are mixed with N2 or when C2H4 at 100 µl·liter-1, or more, is added. For lower concentrations, or when both O2 and CO2 are combined with N2, then the precision is ±10%.

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48

Geçici, Birol, Şadan Korkmaz, Soner Özen, Volkan Şenay e Suat Pat. "Influence of oxygen partial pressure on the metastable copper oxide thin films". Modern Physics Letters B 30, n.º 35 (20 de dezembro de 2016): 1530012. http://dx.doi.org/10.1142/s0217984915300124.

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Paramelaconite (Cu4O3) is a metastable copper oxide. Metastable copper oxide thin films were deposited on glass substrates by reactive RF magnetron sputtering in argon (Ar) and oxygen (O2) gas mixture atmospheres. Ar/O2 gas ratios in the sputtering ambient were chosen as 1/1 and 1/9. The surface and optical properties were determined by X-ray diffractometer (XRD), atomic force microscope (AFM) and UV-Vis spectrophotometer. The XRD patterns of the samples exhibited single strong diffraction peaks at 35.39[Formula: see text] and 35.49[Formula: see text], corresponding to the (202) peak of Cu4O3. The mean thickness values were measured as 100 nm and 80 nm for the films deposited at 1/1 and 1/9 Ar/O2 gas ratios, respectively. The samples showed low transmittance and high absorbance in the high frequency region.

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Makarov, A. F., M. A. Kotsky, А. А. Ton'shin e I. V. Bukhtiyarov. "ARTIFICIAL HYPOBIOSIS AS A METHOD TO MITIGATE THE NEGATIVE EFFECT OF OXYGEN AT AN ELEVATED PARTIAL PRESSURE". Aerospace and Environmental Medicine 55, n.º 5 (2021): 64–68. http://dx.doi.org/10.21687/0233-528x-2021-55-5-64-68.

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To assess how hypobiosis modifies the negative effect of a high partial pressure of oxygen, goldhamsters were put into artificial hypobiosis followed by a simulated O2 poisoning at absolute gas pressure of 7 kgf/cm2. The experiment showed an increase in 1.4 times (p = 0.0579) of the period preceding convulsions; reduction in 3.7 times (p = 0.0009) of the period of stabilization on return to normal O2 pressure, reduction of the total convulsions period in 2.3 times (p = 0.0003).

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50

Winslow, Robert M., Armando Gonzales, Maria L. Gonzales, Michael Magde, Michael McCarthy, Ronald J. Rohlfs e Kim D. Vandegriff. "Vascular resistance and the efficacy of red cell substitutes in a rat hemorrhage model". Journal of Applied Physiology 85, n.º 3 (1 de setembro de 1998): 993–1003. http://dx.doi.org/10.1152/jappl.1998.85.3.993.

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We have compared polyethylene glycol-modified bovine hemoglobin (PEG-Hb; high O2 affinity, high viscosity, high oncotic pressure) and human hemoglobin cross-linked between the α-chains (αα-Hb; low O2affinity, low viscosity, low oncotic pressure) with a non-O2-carrying plasma expander (pentastarch, high viscosity and oncotic pressure) after a 50% (by volume) exchange transfusion followed by a severe (60% of blood volume) hemorrhage. Mean arterial pressure and systemic vascular resistance rose significantly in the αα-Hb but not in the PEG-Hb animals. Two-hour survival was greater in the PEG-Hb animals (93%) than in control (35%), pentastarch (8%), or αα-Hb (6%) animals. In the PEG-Hb animals, there was no disturbance of acid-base balance, significantly less accumulation of lactic acid, and higher cardiac output than in the other groups. The data suggest that the rise in vascular resistance that follows αα-Hb exchange transfusion offsets the additional O2 transport provided by the cell-free hemoglobin. When resistance does not rise, as with PEG-Hb, even relatively small amounts of cell-free hemoglobin appear to be a very effective blood replacement.

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