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Letteratura scientifica selezionata sul tema "Oxygen (O2)"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 6 febbraio 2022

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Articoli di riviste sul tema "Oxygen (O2)"

Reading, Stacey A., and Maggie Yeomans. "Oxygen absorption by skin exposed to oxygen supersaturated water." Canadian Journal of Physiology and Pharmacology 90, no. 5 (May 2012): 515–24. http://dx.doi.org/10.1139/y2012-020.

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The present study tests the hypothesis that skin on the plantar surface of the foot absorbs oxygen (O2) when immersed in water that has a high dissolved O2 content. Healthy male and female subjects (24.2 ± 1.4 years) soaked each foot in tap water (1.7 ± 0.1 mg O2·L–1; 30.7 ± 0.3 °C) or O2-infused water (50.2 ± 1.7 mg O2·L–1; 32.1 ± 0.5 °C) for up to 30 min in 50 different experiments. Transcutaneous oximetry and near infrared spectroscopy were used to evaluate changes in skin PO2, oxygenated haemoglobin, and cytochrome oxidase aa3 that resulted from treatment. Compared with the tap water condition, tissue oxygenation index was 3.5% ± 1.3% higher in feet treated for 30 min with O2-infused water. This effect persisted after treatment, as skin PO2 was higher in feet treated with O2-infused water at 2 min (237 ± 9 vs. 112 ± 5 mm HG) and 15 min (131 ± 1 vs. 87 ± 4 mm HG) post-treatment. When blood flow to the foot was occluded for 5 min, feet resting in O2-infused water maintained a 3-fold higher O2 consumption rate than feet treated with tap water (9.1 ± 1.4 vs. 3.0 ± 1.0 µL·100 g–1·min–1). We estimate that skin absorbs 4.5 mL of O2·m–2·min–1 from O2-infused water. Thus, skin absorbs appreciable amounts of O2 from O2-infused water. This finding may prove useful and assist development of treatments targeting skin diseases with ischemic origin.

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Mangum, C. P. "Oxygen transport in invertebrates." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 248, no. 5 (May 1, 1985): R505—R514. http://dx.doi.org/10.1152/ajpregu.1985.248.5.r505.

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The distribution of the O2 carrying proteins suggests that the original transport system was a hemoglobin similar to the alpha-chain of hemoglobin A and packaged in a nucleated red blood cell. These molecules, which occur in large open fluid compartments, function as O2 stores for regular periods of hypoxia as well as carriers between sites of gas exchange. When the closed circulatory system first arose, the red blood cell was abandoned in favor of extracellular heme proteins, and the O2 storage function became less important. Alternative O2 carriers, hemerythrins, appear in the blood at about the same phylogenetic level as the intracellular hemoglobins, and their respiratory functions appear to be similar. The presence of hemoglobins instead of hemerythrins in the vertebrates may be an evolutionary accident. Still other O2 carriers, hemocyanins, arose separately in two specialized groups that left no descendants. Their O2 binding has all the adaptive features of vertebrate hemoglobin O2 binding, with unique features also. The respiratory function of the hemocyanins is largely limited to O2 transport, which makes a far greater contribution to aerobic metabolism than the O2 carriers found in simpler systems.

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Hochachka, P. W. "Metabolic suppression and oxygen availability." Canadian Journal of Zoology 66, no. 1 (January 1, 1988): 152–58. http://dx.doi.org/10.1139/z88-021.

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The aerobic metabolic rates of cells, tissues, and even whole organisms remain relatively constant down to very low values (O2-regulating response) or decline steadily with O2 availability (O2-conforming response). (O2-regulating systems attempt to make up the energy deficit arising when O2 uptake begins to decline by activating anaerobic metabolism; this process is termed the Pasteur effect and typically involves 5- to 15-fold increases in glucose utilization rates. O2 conformers do not make up the energy deficit and thus enter a metabolically arrested state as O2 availability declines. Current data suggest that O2 conformers can maintain coupled metabolism–membrane functions at metabolically arrested states while O2 regulators cannot, presumably because of more permeable membranes and thus higher energy-dependent ion pumping requirements. These fundamental differences in response to, and tolerance of, hypoxia may be related to qualitative or quantitative differences in inducible stress proteins during O2 deprivation.

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Hoffman, David L., and Paul S. Brookes. "Oxygen Sensitivity of Mitochondrial Reactive Oxygen Species Generation Depends on Metabolic Conditions." Journal of Biological Chemistry 284, no. 24 (April 14, 2009): 16236–45. http://dx.doi.org/10.1074/jbc.m809512200.

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The mitochondrial generation of reactive oxygen species (ROS) plays a central role in many cell signaling pathways, but debate still surrounds its regulation by factors, such as substrate availability, [O2] and metabolic state. Previously, we showed that in isolated mitochondria respiring on succinate, ROS generation was a hyperbolic function of [O2]. In the current study, we used a wide variety of substrates and inhibitors to probe the O2 sensitivity of mitochondrial ROS generation under different metabolic conditions. From such data, the apparent Km for O2 of putative ROS-generating sites within mitochondria was estimated as follows: 0.2, 0.9, 2.0, and 5.0 μm O2 for the complex I flavin site, complex I electron backflow, complex III QO site, and electron transfer flavoprotein quinone oxidoreductase of β-oxidation, respectively. Differential effects of respiratory inhibitors on ROS generation were also observed at varying [O2]. Based on these data, we hypothesize that at physiological [O2], complex I is a significant source of ROS, whereas the electron transfer flavoprotein quinone oxidoreductase may only contribute to ROS generation at very high [O2]. Furthermore, we suggest that previous discrepancies in the assignment of effects of inhibitors on ROS may be due to differences in experimental [O2]. Finally, the data set (see supplemental material) may be useful in the mathematical modeling of mitochondrial metabolism.

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Kizaki, Z., and R. G. Thurman. "Stimulation of oxygen uptake by glucagon is oxygen dependent in perfused rat liver." American Journal of Physiology-Gastrointestinal and Liver Physiology 256, no. 2 (February 1, 1989): G369—G376. http://dx.doi.org/10.1152/ajpgi.1989.256.2.g369.

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Livers from well-fed female Sprague-Dawley rats (100-150 g) were perfused at flow rates of 4 or 8 ml.g liver-1.min-1 to deliver O2 to the organ at various rates. During perfusion at normal flow rates (4 ml.g-1.min-1), glucagon (10 nM) increased O2 uptake in perfused liver by approximately 40 mumol.g-1.h-1. In contrast, glucagon increased O2 uptake by nearly 100 mumol.g-1.h-1 when livers were perfused at high flow rates. Increase in O2 uptake was directly proportional to flow rate and was blocked partially by infusion of phorbol myristate acetate (100 nM) before glucagon. Increase in O2 uptake due to elevated flow was not due to enhanced glucagon delivery, since infusion of 120 nM glucagon at normal flow rates only increased O2 uptake by approximately 40 mumol.g-1.h-1. On the other hand, when O2 tension in the perfusate was manipulated at normal flow rates, the stimulation of O2 uptake by glucagon increased proportional to the average O2 tension in the liver. Infusion of 8-bromo-adenosine 3',5'-cyclic monophosphate (BrcAMP; 25 microM) also increased O2 uptake more than twice as much at high compared with normal flow rates. In the presence of angiotensin II (5 nM), a hormone that increases intracellular calcium, glucagon increased O2 uptake by nearly 100 mumol.g-1.h-1 at normal flow rates. Infusion of glucagon or BrcAMP into livers perfused at normal flow rates increased state 3 rates of O2 uptake of subsequently isolated mitochondria significantly by approximately 25%. In contrast, perfusion with glucagon or BrcAMP at high flow rates increased mitochondrial respiration by 50-60%. Glucagon addition acutely to suspensions of mitochondria, however, had no effect on O2 uptake. These data are consistent with reports that glucagon administration in vivo or treatment of intact cells with glucagon increases O2 uptake of subsequently isolated mitochondria, a phenomenon that can account for the observed increase in O2 uptake in livers perfused at high flow rates with glucagon. Furthermore, these results are consistent with the hypothesis that the effect of glucagon on mitochondria is O2 dependent in the perfused liver. This is most likely due to an effect of intracellular calcium on a mechanism mediated via cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)

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Nakagawa, Y., T. Matsumura, M. Goto, W. Qu, F. C. Kauffman, and R. G. Thurman. "Increase in oxygen uptake due to arachidonic acid is oxygen dependent in the perfused liver." American Journal of Physiology-Gastrointestinal and Liver Physiology 266, no. 5 (May 1, 1994): G953—G959. http://dx.doi.org/10.1152/ajpgi.1994.266.5.g953.

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The purpose of this study was to determine whether the effect of arachidonic acid on hepatic O2 uptake is O2 dependent and which region of the liver lobule it affects. In livers perfused at normal flow rates, infusion of arachidonate increased O2 uptake significantly by about 20-25 mumol.g-1.h-1. When the flow rate was doubled to make the hepatic O2 gradient shallower, the increase in O2 uptake due to arachidonate was two to three times larger (i.e., approximately 50 mumol.g-1.h-1). In livers perfused in the retrograde direction, maximal rates of O2 uptake were about twofold higher in upstream pericentral than in downstream periportal regions, and arachidonic acid nearly doubled O2 uptake in downstream areas without affecting rates in upstream regions. Thus it is concluded that arachidonate stimulates O2 uptake in an O2-dependent manner. This effect was sensitive to an inhibitor of the lipoxygenase, nordihydroguaiaretic acid, in perfused liver but not in isolated hepatocytes. In addition, conditioned medium from Kupffer cells incubated at high O2 tension stimulated parenchymal cell O2 uptake. Furthermore, arachidonate increased intracellular Ca2+ in isolated Kupffer cells in a dose-dependent manner. These findings suggest that eicosanoids produced by nonparenchymal cells participate in a hepatic O2 sensor mechanism involving Ca2+ that regulates O2 uptake by parenchymal cells in the liver.

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Puntarulo, S., and A. I. Cederbaum. "Effect of oxygen concentration on microsomal oxidation of ethanol and generation of oxygen radicals." Biochemical Journal 251, no. 3 (May 1, 1988): 787–94. http://dx.doi.org/10.1042/bj2510787.

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The iron-catalysed production of hydroxyl radicals, by rat liver microsomes (microsomal fractions), assessed by the oxidation of substrate scavengers and ethanol, displayed a biphasic response to the concentration of O2 (varied from 3 to 70%), reaching a maximal value with 20% O2. The decreased rates of hydroxyl-radical generation at lower O2 concentrations correlates with lower rates of production of H2O2, the precursor of hydroxyl radical, whereas the decreased rates at elevated O2 concentrations correlate with lower rates (relative to 20% O2) of activity of NADPH-cytochrome P-450 reductase, which reduces iron and is responsible for redox cycling of iron by the microsomes. The oxidation of aniline or aminopyrine and the cytochrome P-450/oxygen-radical-independent oxidation of ethanol also displayed a biphasic response to the concentration of O2, reaching a maximum at 20% O2, which correlates with the dithionite-reducible CO-binding spectra of cytochrome P-450. Microsomal lipid peroxidation increased as the concentration of O2 was raised from 3 to 7 to 20% O2, and then began to level off. This different pattern of malondialdehyde generation compared with hydroxyl-radical production probably reflects the lack of a role for hydroxyl radical in microsomal lipid peroxidation. These results point to the complex role for O2 in microsomal generation of oxygen radicals, which is due in part to the critical necessity for maintaining the redox state of autoxidizable components of the reaction system.

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Han, Jiuli, Lu Bai, Bingbing Yang, Yinge Bai, Shuangjiang Luo, Shaojuan Zeng, Hongshuai Gao, et al. "Highly Selective Oxygen/Nitrogen Separation Membrane Engineered Using a Porphyrin-Based Oxygen Carrier." Membranes 9, no. 9 (September 3, 2019): 115. http://dx.doi.org/10.3390/membranes9090115.

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Air separation is very important from the viewpoint of the economic and environmental advantages. In this work, defect-free facilitated transport membranes based on poly(amide-12-b-ethylene oxide) (Pebax-2533) and tetra(p-methoxylphenyl)porphyrin cobalt chloride (T(p-OCH3)PPCoCl) were fabricated in systematically varied compositions for O2/N2 separation. T(p-OCH3)PPCoCl was introduced as carriers that selectively and reversibly interacted with O2 and facilitated O2 transport in the membrane. The T(p-OCH3)PPCoCl had good compatibility with the Pebax-2533 via the hydrogen bond interaction and formed a uniform and thin selective layer on the substrate. The O2 separation performance of the thin film composite (TFC) membranes was improved by adding a small amount of the T(p-OCH3)PPCoCl and decreasing the feed pressure. At the pressure of 0.035 MPa, the O2 permeability and O2/N2 selectivity of the 0.6 wt % T(p-OCH3)PPCoCl/Pebax-2533 was more than 3.5 times that of the Pebax-2533 TFC membrane, which reached the 2008 Robeson upper bound. It provides a candidate membrane material for O2/N2 efficient separation in moderate conditions.

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Zhou, J., B. Delille, F. Brabant, and J. L. Tison. "Insights into oxygen transport and net community production in sea ice from oxygen, nitrogen and argon concentrations." Biogeosciences 11, no. 18 (September 18, 2014): 5007–20. http://dx.doi.org/10.5194/bg-11-5007-2014.

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Abstract. We present and compare the dynamics (i.e., changes in standing stocks, saturation levels and concentrations) of O2, Ar and N2 in landfast sea ice, collected in Barrow (Alaska), from February through June 2009. The comparison suggests that the dynamic of O2 in sea ice strongly depends on physical processes (gas incorporation and subsequent transport). Since Ar and N2 are only sensitive to the physical processes in the present study, we then discuss the use of O2 / Ar and O2 / N2 to correct for the physical contribution to O2 supersaturations, and to determine the net community production (NCP). We conclude that O2 / Ar suits better than O2 / N2, due to the relative abundance of O2, N2 and Ar, and the lower biases when gas bubble formation and gas diffusion are maximized. We further estimate NCP in the impermeable layers during ice growth, which ranged from −6.6 to 3.6 μmol O2 L−1 d−1, and the concentrations of O2 due to biological activity in the permeable layers during ice decay (3.8 to 122 μmol O2 L−1). We finally highlight the key issues to solve for more accurate NCP estimates in the future.

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Trushina, Aleksandra P., Veniamin G. Goldort, Sergei A. Kochubei та Alexey V. Baklanov. "UV-photoexcitation of encounter complexes of oxygen O2–O2 as a source of singlet oxygen O2(1Δg) in gas phase". Chemical Physics Letters 485, № 1-3 (січень 2010): 11–15. http://dx.doi.org/10.1016/j.cplett.2009.11.058.

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Più fonti

Tesi sul tema "Oxygen (O2)"

Arcidiacono, Paul. "Nouvelles électrodes pour électrolyseurs H2/O2." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT196.

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L’efficacité énergétique d’un électrolyseur alcalin est liée aux surtensions de réactions aux électrodes. Dans le but d’améliorer cette efficacité, nous avons développé de nouvelles électrodes composites polymère/particules maximisant la surface active des meilleurs catalyseurs, les propriétés de conductivité électrique et de transport des espèces en choisissant le polymère-liant le plus avantageux pour la cinétique réactionnelle. Les notions théoriques et l’état de l’art des principaux matériaux d’anodes et de cathodes et des différents paramètres régissant le fonctionnement d’un électrolyseur alcalin sont présentés afin de faire une synthèse des nombreux travaux réalisés. Des méthodes de fabrication d’électrodes au laboratoire ou lors d’essais préindustriels ont été explorées et comparées. Les performances électrochimiques des cathodes et anodes composites développées pour les réactions de l’évolution d’hydrogène et d’oxygène en milieu alcalin concentré sont étudiées par voltammétrie cyclique, polarisation linéaire et spectroscopie d’impédance électrochimique. Ce travail donne lieu à la description des différents paramètres clés du fonctionnement des électrodes composites polymère/particules. Différentes formulations de cathodes et d’anodes ont donc été étudiées afin d’établir des corrélations entre les propriétés physico-chimiques des polymères liants et des particules sur le comportement électrochimique des électrodes réalisées. Ces résultats sont discutés en termes de surtension de réactions, de cinétique électrochimique et de densités de sites actifs. Enfin, les résultats de la mise à l’échelle des cathodes composites et de leur procédé de fabrication pour une application industrielle sont rapportés avec l’objectif d’intégrer celles qui ont démontré des performances supérieures à celles de l’état de l’art dans un dispositif prototype industriel d’électrolyse. La démarche de la mise à l’échelle, les moyens expérimentaux développés, et une partie des résultats des essais y sont présentés<br>The electrolyzer efficiency is directly related to the electrode reaction overpotentials. To improve this efficiency, new composite electrodes with selected binders and electrocatalysts showing large active area have been formulated to enhance the electrochemical kinetics. First, a state of the art of electrode materials and electrolysis parameters have been reported in a relevant literature survey about different topics developed in the thesis manuscript. Then, a few laboratory and preindustrial electrode fabrication processes were explored and compared on both technical and economical aspects. Moreover, the electrochemical performances of composite cathodes and anodes for hydrogen and oxygen evolution reactions have been studied by cyclic voltammetry, linear polarization and electrochemical impedance spectroscopy. This comprehensive study leads to a precise description of the interfacial phenomena at the microscopic scale during gas production and the evaluation of key parameters for the formulation of advanced electrodes. Many electrode formulations were studied for the correlation of physicochemical properties of components and corresponding electrochemical behaviors. These results are discussed in terms of overpotentials, electrochemical kinetics and active site density. Finally, scale-up of composite cathode is reported. The aim of this work is to integrate the best formulated composite electrodes in a real scale prototype. The scale-up process, experimental devices developed and some electrochemical results are presented

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Liu, Jia. "The O2 electrode performance in the Li-O2 battery." Doctoral thesis, Uppsala universitet, Strukturkemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-259589.

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Li-O2 batteries have been attracting increasing attention and R&D efforts as promising power sources for electric vehicles (EVs) due to their significantly higher theoretical energy densities compared to conventional Li-ion batteries. The research presented in this thesis covers the investigation of factors influencing the decomposition of Li2O2, the development of highly active electrocatalysts, and the design of low-cost and easy-operation binder-free O2 electrodes for Li-O2 batteries. Being the main technique, SR-PXD was used both as a continuous light source to advance the electrochemical decomposition of Li2O2 under the X-ray illumination and an operando tool that allowed us to probe the degradation of Li2O2. Since XRD was intensively used in my thesis work, the effect of X-ray irradiation on the stability of Li2O2 was studied. The accelerating effect of X-rays on the electrochemical decomposition of Li2O2 was, for the first time, explored. The electrochemical decomposition rate of Li2O2 was proportional to the X-ray intensity used. It is proposed that the decomposition might involve a three-step reaction with [Li2O2]x+ and Li2-xO2* as intermediates, which followed pseudo-zero-order kinetics. Then, three electrocatalysts (Pt/MNT, Ru/MNT and Li2C8H2O6) were developed, which exhibited good electrocatalytic performances during the OER. Their activities were evaluated by following the Li2O2 decomposition in electrodes during the charging processes. In addition, the time-resolved OER kinetics for the electrocatalyst-containing Li-O2 cells charged galvanostatically and potentiostatically was systematically investigated using operando SR-PXD. It was found that a small amount of Pt or Ru decoration on the MNTs enhanced the OER efficiency in a Li-O2 cell. The Li2O2 decomposition of an electrode with 5 wt% Pt/MNT, 2 wt% Ru/MNT or Li2C8H2O6 in a Li-O2 cell followed pseudo-zero-order kinetics. Finally, a novel binder-free NCPE for Li-O2 batteries was presented. It displayed a bird’s nest microstructure, which could provide the self-standing electrode with considerable mechanic durability, fast O2 diffusion and enough space for the discharge product deposition. The NCPE contained N-containing functional groups, which may promote the electrochemical reactions.

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Zhang, Wensheng. "SO2/O2 as an oxidant in hydrometallurgy." Murdoch University, 2000. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20080115.141151.

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Chen, Guo. "O2 Carrier Facilitated O2 Transport in a Hepatic Hollow Fiber Bioreactor." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1283207065.

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Liu, Zheng. "Synthesis and battery application of nanomaterials and the mechanism of O2 reduction in aprotic Li-O2 batteries." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/15694.

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Hunting for improved energy storage devices based on rechargeable Li-ion batteries and other advanced rechargeable batteries is one of the hottest topics in today's society. Both Li- ion batteries and Li-O2 batteries have been studied within the thesis. The research work of this thesis contains two different parts. Part 1. The controlled synthesis of the extreme small sized nanoparticles and their application for Li-ion batteries; Part 2. The study of the O2 reduction mechanism in Li-O2 batteries with aprotic electrolytes. In the first part, two different types of extremely small-sized TiO2 nanoparticles with at lease on dimension less than 3 nm was synthesised via solvothermal/hydrothermal reaction, i.e., anatase nanosheets and TiO2(B). These nanoparticles were obtained without any contamination of long chain organic surfactants. A series of systematic characterisation methods were employed to analyse the size, phase purity, and surface condition. These extremely small-sized nanoparticles exhibit improved capacity, rate performance as anode materials for Li-ion batteries. The shapes of load curves of charge and discharge are significantly modified due to the reduced size of TiO2 nanoparticles. In chapter 3, we will see the variation of the capacity and the load curve shape of the anatase nanosheets according to their thickness and surface conditions. The origin of the excessive capacity is analysed based on the electrochemical data. It has been identified that both pseudocapacitive (interfacial) Li+ storage and the excessive Li+ -storage from the bulk contribute to the increased capacity. In chapter 4, the shape and size of the sub-3 nm TiO2(B) nanoparticles are studied, a method based the PXRD data is established. These nanoparticles demonstrate a reversible capacity of 221 mAh/g at a rate of 600 mA/g and remain 135 mAh/g at 18000 mA/g without significant capacity fading during cycling. In the last part, a systematic study of O2 reduction mechanism for aprotic Li-O2 batteries based on the combination of a series of electrochemical and spectroscopic data is presented. The novel mechanism unifies two previous models for the growth of Li2O2 during discharge, i.e., Li2O2 particle formation in the solution phase and Li2O2 film formation on the electrode surface. The new mechanism provides fundamental conceptions for the improvement of Li2O2 batteries and shed light on the future research of Li2O2 batteries.

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Zhou, Haiying. "Multi-scale model analysis of O2 transport and metabolism effects of hypoxia and exercise /." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1254502393.

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Laferty, Edward Alan. "Oxygen and Carbon Dioxide Levels During Qualitative Respirator Fit Testing." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1086808006.

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Bresolí, Obach Roger. "Novel strategies for singlet molecular oxygen O2(1Δg) generation and detection in cells". Doctoral thesis, Universitat Ramon Llull, 2018. http://hdl.handle.net/10803/662972.

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En aquesta tesi s'han utilitzat diferents estratègies per obtenir control en la producció i detecció de diferents espècies reactives d'oxigen (ROS), especialment per a l'oxigen singlet (1O2). En la primera part de la tesi, l'enfoc principal consisteix en entendre la generació de ROS i intentar potenciar-ne el seu efecte. En primer lloc, demostrem que la modificació de diferents fotosensibilitzadors afegint-hi un catió de trifenilfosfoni com a element diana produeix derivats amb una excel·lent activitat fotoantimicrobiana contra bacteris Gram-positius (S. aureus i E. faecalis). En segon lloc, descobrim una sèrie de nous aspectes de la reacció de “-phenyl quenching” per derivats de 9-fenilfenalenona. La fototoxicitat d’aquests derivats ja es troba esmentada en el llibre: “L'origen de les espècies” de C. Darwin. També es suggereix una via metabòlica mediada per la reacció BPQ en la biosíntesi dels pigments vegetals derivats de fluorones. A més, si el grup fenil és substituït per altres grups arils, s'observa diferencies en la reacció de BPQ. En tercer lloc, s’ha demostrat que diferents antraquinones d’origen natural indueixen fototoxicitat en biofilms de C. tropicalis a causa de la generació de O2•, tenint l’1O2 un rol menor. En quart lloc, es demostra el fàrmac antitumoral Doxorubicina produeix quantitats significants d’1O2, però es redueix la seva generació quan es complexa amb el ADN. En cinquè lloc, s’ha estudiat l’efecte d’adsorció o unió covalent d’un fotosensibilitzador a nanopartícules mesoporoses de sílice. A més a més, s’han derivatitzat per afegir-hi elements diana. Sisè i últim, s’ha estudiat les propietats fotoquímiques d’una nova diada que conté un bromo-bodipy com a fotosensibilitzador i trampa química de ROS (que desactiva la capacitat del bromo-bodipy de generar 1O2). Un cop oxidada la trampa química, la diada recupera la capacitat de generar 1O2 i causar dany cel·lular. S’observa diferents propietats foto-antitumorals d’aquesta diada en funció de l’estrès cel·lular o de la localització cel·lular. En la segona part de la tesi, s'ha centrat en la detecció de ROS. En primer lloc, s’han dissenyat, sintetitzat i caracteritzat nanosondes fluorescents per la detecció d'1O2 en sistemes biològics. La nanovehiculització elimina algunes de les limitacions de les diferents sondes fluorescents d’1O2. En aquest sentit, diverses sondes tals com SOSG, ADPA o furil-vinil-naftooxazol s’han unit covalentment a nanopartícules utilitzant diferents cadenes espaiadores per tal d’optimitzar la seva reactivitat front 1O2. A diferència de quan es troben lliures en solució, les nanosondes són fàcilment internalitzades per cèl·lules eucariotes i procariotes i es minimitza la interacció amb proteïnes (com per exemple, l’albúmina de sèrum boví). Les diferents nanosondes responen a l’1O2 generat intracel·lular. Com a prova de concepte, també s’ha desenvolupat una nanosonda fluorescent per la detecció no selectiva de ROS, basada en 2’,7’-diclorodihidrofluoresceina. En segon lloc, s’ha caracteritzat la estructura i reactivitat de la sonda fluorescent: CellROX Deep Red. En tercer lloc, s’ha desenvolupat la primera sonda d’optoacústica per la detecció de ROS basada en l’oxidació de la tetrametilbenzidina. S’ha aconseguit detectar 1O2 produït per bacteris utilitzant tal sonda. Finalment i com a prova de concepte, s’ha dissenyat un “self-reporter” nanofotosensibilitzador. El nanosistema és capaç de produir i detectar 1O2 simultàniament. Aquest nanodispositiu s'ha utilitzat amb èxit per la fotoinactivació de S. aureus, observant-se una correlació entre el canvi de fluorescència de la sonda i la mort bacteriana.<br>En esta tesis se han utilizado distintas estrategias para obtener el control en la producción y detección de diferentes especies reactivas de oxígeno (ROS), especialmente para el oxígeno singlete (1O2). En la primera parte de la tesis, el enfoque principal consiste en entender la generación de ROS e intentar potenciar su efecto. En primer lugar, demostramos que la modificación de distintos fotosensibilizadores, añadiendo un catión de trifenilfosfonio como elemento diana, produce derivados con una excelente actividad fotoantimicrobiana contra bacterias Gram-positivas (S. aureus y E. faecalis). En segundo lugar, descubrimos una serie de nuevos aspectos de la reacción de "-phenyl quenching" por derivados de 9-fenilfenalenona. La fototoxicidad de estos derivados ya se encuentra mencionada en el libro: "el origen de las especies" de C. Darwin. También se sugiere una vía metabólica mediada por la reacción BPQ en la biosíntesis de los pigmentos vegetales derivados de fluorenonas. Además, si el grupo fenilo es sustituido por otros grupos arilos, se observan diferencias en la reacción de BPQ. En tercer lugar, se ha demostrado que distintas antraquinonas de origen natural inducen fototoxicidad en biofilms de C. tropicalis debido a la generación de O2•, teniendo el 1O2 un rol menor. En cuarto lugar, se demuestra que el fármaco antitumoral Doxorubicina produce cantidades significantes de 1O2, pero se reduce su generación cuando se compleja con el ADN. En quinto lugar, se ha estudiado el efecto de adsorción o unión covalente de un fotosensibilizador a nanopartículas mesoporosas de sílice. Además, se han derivatizado para añadir elementos diana. Sexto y último, se han estudiado las propiedades fotoquímicas de una nueva diada que contiene un bromo-bodipy como fotosensibilizador y trampa química de ROS (que desactiva la capacidad del bromo-bodipy para generar 1O2). Una vez oxidada la trampa química, la diada recupera la capacidad para generar 1O2 y causar daño celular. Se observan diferentes propiedades foto-antitumorales de esta diada en función del estrés celular o de la localización celular. La segunda parte de la tesis, se ha centrado en la detección de ROS. En primer lugar, se han diseñado, sintetizado y caracterizado nanosondas fluorescentes para la detección de 1O2 en sistemas biológicos. La nanovehiculización elimina algunas de las limitaciones de las distintas sondas fluorescentes de 1O2. En este sentido, varias sondas tales como SOSG, ADPA o furilo-vinilo-naftooxazol se han unido covalentemente a nanopartículas utilizando distintas cadenas espaciadoras para optimizar su reactividad frente 1O2. A diferencia de cuando se encuentran libres en solución, las nanosondas son fácilmente internalizadas por células eucariotas y procariotas y se minimiza la interacción con proteínas (como por ejemplo con la albúmina de suero bovino). Las distintas nanosondas responden al 1O2 generado intracelular. Como prueba de concepto, también se ha desarrollado una nanosonda fluorescente para la detección no selectiva de ROS, basada en 2',7'-diclorodihidrofluoresceina. En segundo lugar, se ha caracterizado la estructura y reactividad de la sonda fluorescente: CellROX Deep Red. En tercer lugar, se ha desarrollado la primera sonda de optoacústica para la detección de ROS basada en la oxidación de la tetrametilbenzidina. Se ha logrado detectar 1O2 producido por bacterias emprando tal sonda. Finalmente, y como prueba de concepto, se ha diseñado un "self-reporter" nanofotosensibilitzador. El nanosistema es capaz de producir y detectar 1O2 simultáneamente. Este nanodispositivo ha sido utilizado con éxito para la fotoinactivación de S. aureus, observándose una correlación entre el cambio de fluorescencia de la sonda y la muerte bacteriana.<br>In this thesis, different strategies have been used in order to gain control in reactive oxygen species (ROS) production and detection, especially for singlet oxygen (1O2). In the first part of the thesis, the main focus is towards understanding ROS generation and try to potentiate its effect. First, we demonstrate that modification of different photosensitisers with the triphenylphosphonium cation yields derivatives with an excellent photoantimicrobial activity against Gram‐positive bacteria (i.e., S. aureus and E. faecalis). Second, we uncover a number of new aspects of -phenyl quenching reaction in 9-phenylphenalenone scaffold, whose phototoxicity was already mentioned in Darwin’s Origin of Species. It is suggested an excited state-mediated metabolic pathway in the biosynthesis of fluorone plant pigments. Moreover, if phenyl moiety is substituted for other aryl groups, it is observed that the electrocyclic ring opening back to ground state ketones have lifetimes between miliseconds and picoseconds. Third, we demonstrate that the main photosensitizing mechanism, involved in the photo-induced C. tropicalis antibiofilm activity by natural anthraquinones, is via O2• production, whereas 1O2 participation seems of lesser importance. Fourth, we demonstrate that doxorubicin produces significant amounts of 1O2, however, this is largely suppressed when bound to DNA. Fifth, we studied the effect of PS adsorption or covalently bond onto the surface of mesoporous silica nanoparticles. Moreover, we further derivatitze them for attach targeting elements. Sixth and last, we studied the activation a new dyad comprising a bromo-bodipy, which acts as PS, plus a non-selective ROS chemical trap, which quenches the ability of bromo-bodipy to produce 1O2. For that aPS we observe a differential behaviour in function of the cellular stress or even in function of the organelle. In the second part of the thesis, focus has been shifted towards ROS detection. First, we designed, synthesized, and characterized biocompatible fluorescent nanoprobes for 1O2 detection in biological systems that circumvents many of the limitations of the different molecular 1O2 fluorescent probes. Under that purpose different 1O2 probes (Singlet Oxygen Sensor Green, anthracene dipropionic acid and furyl-vinyl-naphthoxazole) were covalently linked to nanoparticles core using different architectures to optimize their response to 1O2. In contrast to its molecular counterpart, the optimum nanoprobes are readily internalized by prokaryotic and eukaryotic cells and they do not interact with proteins (i.e. bovine serum albumin). Furthermore, the spectral characteristics do not change inside cells, and the probe responds to intracellular generated 1O2 with the corresponding change in fluorescence. As a proof of concept, a non-selective ROS fluorescent nanoprobe, based on diacetyl 2’,7’-dichlorodihydrofluorescein, has been synthetized and successfully used for detecting intracellular ROS. Second, we have performed the chemical characterization of the CellROX Deep Red, a new commercial non-selective ROS fluorescent probe, ascertained its putative chemical structure and evaluated its reactivity towards different reactive oxygen/nitrogen species and light in solution. Third, we developed the first ROS optoacoustic probe based on the oxidation of tetramethylbenzidine and successfully used for detecting 1O2 produced by bacteria. Finally, as proof of concept we have designed a self-reporter nanophotosensitizer. The nanosystem is capable to produce and detect the 1O2 generated simultaneously. It has been successfully used for S. aureus photoinactivation in which a correlation was observed between fluorescent change of the probe and bacterial cellular death.

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Rabie, Samuel Liversage. "SO2 and O2 separation by using ionic liquid absorption / S.L. Rabie." Thesis, North-West University, 2012. http://hdl.handle.net/10394/9100.

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In order to reduce the amount of pollution that is generated by burning fossil fuels alternative energy sources should be explored. Hydrogen has been identified as the most promising replacement for fossil fuels and can be produced by using the Hybrid Sulphur (HyS) cycle. Currently the SO2/O2 separation step in the HyS process has a large amount of knock out drums. The aim of this study was to investigate new technology to separate the SO2 and O2. The technology that was identified and investigated was to separate the SO2 and O2 by absorbing the SO2 into an ionic liquid. In this study the maximum absorption, absorption rate and desorption rate of SO2 from the ionic liquid [BMIm][MeSO4] with purities of 95% and 98% was investigated. These ionic liquid properties were investigated for pure O2 at pressures ranging from 1.5 to 9 bar(a) and for pure SO2 at pressures from 1.5 to 3 bar(a) at ambient temperature. Experiments were also carried out where the composition of the feed-stream to the ionic liquid was varied with compositions of 0, 25, 50, 75 and 100 mol% SO2 with O2 as the balance. For each of these compositions the temperature of the ionic liquid was changed from 30oC to 60oC, in increments of 10oC. The absorption rate of SO2 in the ionic liquid increased when the mole percentage SO2 in the feed stream was increased. When the temperature of the ionic liquid was decreased the maximum amount of SO2 that the ionic liquid absorbed increased dramatically. However, the absorption rate was not influenced by a change in the absorption temperature. The experimental results for the maximum SO2 absorption were modelled with the Langmuir absorption model. The model fitted the data well, with an average standard deviation of 17.07% over all the experiments. In order to determine if the absorption reaction was endothermic or exothermic the Clausius-Clapeyron equation was used to calculate the heat of desorption for the desorption step. The heat of desorption data indicated that the desorption of SO2 from this ionic liquid was an endothermic reaction because the heat of desorption values was positive. Therefore the absorption reaction was exothermic. From the pressure-change experiments the results showed that the mole percentage of O2 gas that was absorbed into the ionic liquid was independent of the pressure of the O2 feed.On the other hand, there was a clear correlation between the mole percentage SO2 that was absorbed into the ionic liquid and the feed pressure of the SO2. When the feed pressure of the SO2 was increased the amount of SO2 absorbed also increased, this trend was explained with Fick’s law. In the study the effect of the ionic liquid purity on the SO2 absorption capacity was investigated. The experimental results for the pressure experiments showed that the 95% and 98% pure ionic liquid absorbed about the same amount of SO2. During the temperature experiments the 95% pure ionic liquid absorbed more SO2 than the 98% pure ionic liquid for all but two of the experiments. However the 95% pure ionic liquid also absorbed small amounts of O2 at 30 and 40oC which indicated that the 95% pure ionic liquid had a lower selectivity than the 98% pure ionic liquid. Therefore, the 95% pure ionic liquid had better SO2 absorption capabilities than the 98% pure ionic liquid. These result showed that the 98% pure ionic liquid did not absorb more SO2 than the 95% pure ionic liquid, but it did, however, show that the 98% pure ionic liquid had a better selectivity towards the SO2. Hence, it can be concluded that even with the O2 that is absorbed it would be economically more advantageous to use the less expensive 95% pure ionic liquid rather than the expensive 98% pure ionic liquid, because the O2 would not influence the performance of the process negatively in such low quantities.<br>Thesis (MIng (Chemical Engineering))--North-West University, Potchefstroom Campus, 2013

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Liu, Chenjuan. "Exploration of Non-Aqueous Metal-O2 Batteries via In Operando X-ray Diffraction." Doctoral thesis, Uppsala universitet, Strukturkemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-330889.

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Non-aqueous metal-air (Li-O2 and Na-O2) batteries have been emerging as one of the most promising high-energy storage systems to meet the requirements for demanding applications due to their high theoretical specific energy. In the present thesis work, advanced characterization techniques are demonstrated for the exploration of metal-O2 batteries. Prominently, the electrochemical reactions occurring within the Li-O2 and Na-O2 batteries upon cycling are studied by in operando powder X-ray diffraction (XRD). In the first part, a new in operando cell with a combined form of coin cell and pouch cell is designed. In operando synchrotron radiation powder X-ray diffraction (SR-PXD) is applied to investigate the evolution of Li2O2 inside the Li-O2 cells with carbon and Ru-TiC cathodes. By quantitatively tracking the Li2O2 evolution, a two-step process during growth and oxidation is observed. This newly developed analysis technique is further applied to the Na-O2 battery system. The formation of NaO2 and the influence of the electrolyte salt are followed quantitatively by in operando SR-PXD. The results indicate that the discharge capacity of Na-O2 cells containing a weak solvating ether solvent depends heavily on the choice of the conducting salt anion, which also has impact on the growth of NaO2 particles. In addition, the stability of the discharge product in Na-O2 cells is studied. Using both ex situ and in operando XRD, the influence of sodium anode, solvent, salt and oxygen on the stability of NaO2 are quantitatively identified. These findings bring new insights into the understanding of conflicting observations of different discharge products in previous studies. In the last part, a binder-free graphene based cathode concept is developed for Li-O2 cells. The formation of discharge products and their decomposition upon charge, as well as different morphologies of the discharge products on the electrode, are demonstrated. Moreover, considering the instability of carbon based cathode materials, a new type of titanium carbide on carbon cloth cathode is designed and fabricated. With a surface modification by loading Ru nanoparticles, the titanium carbide shows enhanced oxygen reduction/evolution activity and stability. Compared with the carbon based cathode materials, titanium carbide demonstrated a higher discharge and charge efficiency.

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Libri sul tema "Oxygen (O2)"

Swift, Kerry. Microwave excitation of oxygen O2(super 1 delta) for an oxygen-iodine laser. Koln: DFVLR, 1989.

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Hitch, B. D. Reduced H2-O2 mechanisms for use in reacting flow simulation. New York: AIAA, 1988.

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1946-, Frimer Aryeh A., ed. Singlet O2. Boca Raton, Fla: CRC Press, 1985.

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Fawkner, Samantha G., and Neil Armstrong. Oxygen uptake kinetics. Oxford University Press, 2013. http://dx.doi.org/10.1093/med/9780199232482.003.0022.

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The two main purposes of Chapter 22 are to (i) explore the methodological issues involved in assessing the O2 kinetic response to exercise in children, and (ii) explain the O2 kinetic response to exercise in children and review the literature regarding changes with age and sex and with respect to conventional markers of aerobic fitness.

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Kato, Masato. Oxygen Potentials and Defect Chemistry in Nonstoichiometric (U, Pu)O2. INTECH Open Access Publisher, 2012.

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Temperature dependence of the collisional removal of O2(A(sup 3)Sigma(sup +)(sub u), upsilon=9) with O2 and N2. [Washington, DC: National Aeronautics and Space Administration, 1997.

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A, Copeland Richard, and United States. National Aeronautics and Space Administration., eds. Temperature dependence of the collisional removal of O2(A(sup 3)Sigma(sup +)(sub u), upsilon=9) with O2 and N2. [Washington, DC: National Aeronautics and Space Administration, 1997.

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Zhang, Wensheng. SO 2/O2 as an oxidant in hydrometallurgy. Murdoch University, 2000.

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Kreit, John W. Gas Exchange. Edited by John W. Kreit. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190670085.003.0002.

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Gas Exchange explains how four processes—delivery of oxygen, excretion of carbon dioxide, matching of ventilation and perfusion, and diffusion—allow the respiratory system to maintain normal partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) in the arterial blood. Partial pressure is important because O2 and CO2 molecules diffuse between alveolar gas and pulmonary capillary blood and between systemic capillary blood and the tissues along their partial pressure gradients, and diffusion continues until the partial pressures are equal. Ventilation is an essential part of gas exchange because it delivers O2, eliminates CO2, and determines ventilation–perfusion ratios. This chapter also explains how and why abnormalities in each of these processes may reduce PaO2, increase PaCO2, or both.

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Capitoli di libri sul tema "Oxygen (O2)"

Baak, Marleen A., Bernard Gutin, Kim A. Krawczewski Carhuatanta, Stephen C. Woods, Heinz W. Harbach, Megan M. Wenner, Nina S. Stachenfeld, et al. "Oxygen (O2)." In Encyclopedia of Exercise Medicine in Health and Disease, 683. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-540-29807-6_2827.

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Baak, Marleen A., Bernard Gutin, Kim A. Krawczewski Carhuatanta, Stephen C. Woods, Heinz W. Harbach, Megan M. Wenner, Nina S. Stachenfeld, et al. "Oxygen (O2) Debt." In Encyclopedia of Exercise Medicine in Health and Disease, 683. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-540-29807-6_2826.

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A, S. L., E. K. W, H. L. R, and E. M. "Molecular Identification of O2 Sensors and O2-Sensitive Potassium Channels in the Pulmonary Circulation." In Oxygen Sensing, 219–40. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/0-306-46825-5_21.

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O’Kelly, Ita, Chris Peers, and Paul J. Kemp. "O2-Sensing by Model Airway Chemoreceptors." In Oxygen Sensing, 611–22. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/0-306-46825-5_59.

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Jue, Thomas, Youngran Chung, Paul Mole, Tuan Khan Tran, Ulrike Kreutzer, Napapon Sailasuta, and Ralph Hurd. "O2 and Respiration in Exercising Human Muscle." In Oxygen Sensing, 769–83. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/0-306-46825-5_77.

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Sawyer, Donald T. "The Chemistry and Activation of Dioxygen Species (O2, O2 -., and HOOH) in Biology." In Oxygen Complexes and Oxygen Activation by Transition Metals, 131–48. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0955-0_11.

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Bocci, Velio. "Rectal Insufflation of O2-O3 (RI)." In Oxygen-Ozone Therapy, 213–22. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-015-9952-8_19.

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Fercher, Andreas, Alexander V. Zhdanov, and Dmitri B. Papkovsky. "O2 Imaging in Biological Specimens." In Phosphorescent Oxygen-Sensitive Probes, 71–101. Basel: Springer Basel, 2012. http://dx.doi.org/10.1007/978-3-0348-0525-4_3.

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Haddad, Gabriel G., and Huajun Liu. "Different O2-Sensing Mechanisms by Different K+ Channels." In Oxygen Sensing, 441–52. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/0-306-46825-5_43.

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Thompson, Roger J., and Colin A. Nurse. "O2-Chemosensitivity in Developing Rat Adrenal Chromaffin Cells." In Oxygen Sensing, 601–9. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/0-306-46825-5_58.

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Atti di convegni sul tema "Oxygen (O2)"

ALLEN, ROBERT C. "MOLECULAR OXYGEN (O2): REACTIVITY AND LUMINESCENCE." In Bioluminescence and Chemiluminescence - Progress and Current Applications - 12th International Symposium on Bioluminescence (BL) and Chemiluminescence (CL). WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812776624_0049.

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Torbin, A. P., M. C. Heaven, V. N. Azyazov, A. A. Pershin, and A. M. Mebel. "O2(a1∆) vibrational kinetics in oxygen-iodine laser." In Saratov Fall Meeting 2017: Fifth International Symposium on Optics and Biophotonics: Laser Physics and Photonics XIX; Computational Biophysics and Analysis of Biomedical Data IV, edited by Vladimir L. Derbov and Dmitry E. Postnov. SPIE, 2018. http://dx.doi.org/10.1117/12.2317881.

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McGillis, Wade R., Chris Langdon, Albert J. Williams, and Brice Loose. "O2-MAVS: An instrument for measuring oxygen flux." In OCEANS 2009. IEEE, 2009. http://dx.doi.org/10.23919/oceans.2009.5422166.

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Rakhimova, T., A. Kovalev, A. Rakhimov, K. Klopovsky, D. Lopaev, Y. Mankelevich, and O. Braginsky. "Radio-Frequency Plasma Generation of Singlet Oxygen in O2 and O2:AR (HE) Mixtures." In 34th AIAA Plasmadynamics and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2003. http://dx.doi.org/10.2514/6.2003-4306.

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Deshpande, Girish, Gautham Oroskar, and Derek Oswald. "A Portable Handheld Oxygen Blender: A Novel Design to Reduce Early Oxygen Toxicity." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-36619.

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Oxygen is an essential therapeutic agent used extensively in all hospitals for patients with compromised function of the respiratory or cardiac systems. All patients (with the exception of neonates with certain heart diseases) are resuscitated with 100% oxygen. The American Heart Association Guidelines for Resuscitation state that it is essential in the post-resuscitative phase to decrease the concentration of O2 provided to keep oxyhemoglobin saturation (SpO2) > 94%, with a goal of avoiding hyperoxia while ensuring adequate oxygen delivery. Hyperoxia has been shown to be responsible for worsening tissue injury via oxidative damage following ischemia-reperfusion. Therefore, it is important in the post-resuscitative phase to use the lowest inspired oxygen concentration (FiO2) that will maintain SpO2 ≥ 94%. To address this, clinicians use oxygen blenders: devices that mix room air (21% O2) and medical grade oxygen (100% O2) to create a desirable FiO2. Current oxygen blenders have the disadvantage of being wall-mounted, bulky, and are limited to a small set of oxygen delivery devices (nebulizers, mechanical ventilators) with which they can interface. We developed an oxygen blending device capable of mixing room air and 100% O2 using the venturi principle. The device features a cylindrical body with a venturi nozzle and an entrainment window. It is handheld, portable, and machined from acrylic plastic. An oxygen blender with these features allows for appropriate oxygen therapy during patient transport. As oxygen flows through the device from the inlet orifice, atmospheric air is drawn in through the window, mixed, and then delivered to the patient through the outlet orifice. We designed the outlet orifice to have the same dimensions as the inlet orifice, allowing for universal integration with any device that connects to standard oxygen tubing. The entrainment window area can be adjusted by twisting a cover over the body of the blender, thus adjusting the FiO2 delivery. Using a venturi nozzle of 6.35 mm in diameter and an entrainment window area of 97 mm2, we achieved FiO2 ranging from 40% to 50% using input flow of 100% O2 at 6 L/min at 50 psi (via rotameter). The key feature of this device is that it can be interposed between any standard oxygen tubing allowing control of FiO2 at the bedside of the patient in hospital or during transport. Further work is needed to achieve a wider FiO2 range.

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Kobtsev, V. D., S. A. Kostritsa, V. V. Smirnov, N. S. Titova, and S. A. Torokhov. "IGNITION DELAY REDUCTION IN THE SYNGAS-O2 MIXTURE DUE TO EXCITATION OF O2 MOLECULES TO THE A1-G STATE." In 8TH INTERNATIONAL SYMPOSIUM ON NONEQUILIBRIUM PROCESSES, PLASMA, COMBUSTION, AND ATMOSPHERIC PHENOMENA. TORUS PRESS, 2020. http://dx.doi.org/10.30826/nepcap2018-2-05.

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Experimental studies of the influence of singlet delta oxygen on the ignition delay of syngas-oxygen mixture are performed in a low-pressure flow reactor at a pressure of 16 mbar in a temperature range of 860-930 K. Glow discharge is used for the production of O2(a1As) molecules. The discharge cell and ducts for oxygen plasma supply are covered by HgO in order to decrease the concentrations of oxygen atoms and ozone molecules which are the effective deactivators of O2(a1As) molecules. Diagnostics of O2(a1 -g) and O3 concentrations both in the mixer and along the flow reactor is executed. It is shown that the presence of a small amount of O2(a1As) molecules (4% of the total oxygen) result in the 10%-20% reduction of the induction length in the temperature range 860-930 K. The effect of such an amount of O2(a1 -g) molecules is equivalent to the 30-kelvin heating of the whole mixture. It is revealed on the basis of combined experimental and numerical studies that at low pressure (at least at ~ 10-20 bar), the deactivation of O2(a1As) molecules on the reactor walls contributes significantly to a decrease in the singlet oxygen concentration along the reactor. This effect should be taken into consideration during modeling of the ignition process at low-pressure conditions.

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Vasilchenko, S. S., L. N. Sinitsa, V. I. Serdyukov, B. A. Voronin, and E. R. Polovtseva. "Ground-based spectroscopic measurements of atmospheric oxygen complexes (O2)2." In Eighteenth International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics, edited by Oleg A. Romanovskii. SPIE, 2012. http://dx.doi.org/10.1117/12.2008450.

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Zagidullin, Marsel V. "Liquid-jet O2(1Delta) generator for chemical oxygen-iodine laser." In Gas Flow and Chemical Lasers: Tenth International Symposium, edited by Willy L. Bohn and Helmut Huegel. SPIE, 1995. http://dx.doi.org/10.1117/12.204916.

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Kumar, B. Karthik, James P. Cassell, and Robin N. Coger. "Computational Model to Predict Oxygen Availability for Cells Cultured Under Flow Conditions." In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19334.

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Abstract (sommario):

Tissue bioreactors are flow systems able to support cultured cells over time. Consequently the functionality of these in vivo systems require the cells to be provided with the required substrate, nutrient, and O2. When a bioreactor is used for liver support, the latter requirement is particularly critical since hepatocyte functionalities are highly dependent on O2 [1]. So for bioreactor designers, computational models would serve as a powerful tool for predicting O2 transport dynamics. In the current study, such a model is developed to predict the level of O2 available to hepatocytes dispersed within a porous collagen substrate, for varying flow conditions. This is carried out by intially verifying the model’s accuracy through experiments conducted using a customized flow device and then extending the model to clarify the sensitivity of O2 transport through the cellular space with respect to the flow conditions, the cells’ O2 consumption rates and dissolved O2 levels in the media.

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Shi, Gengbei, and Robin N. Coger. "Enhanced Oxygen Delivery to Liver Tissue Equivalent by Perfluorocarbon." In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19190.

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Bioartificial Liver Devices (BALs) have the potential to serve as a bridge strategy for patients awaiting liver transplants, and also show promise as drug testing platforms for the pharmaceutical industry [1]. Yet the limitations of O2 transport through the 3D tissue structures of current designs continue to present engineering challenges. In previous work our group successfully improved O2 availability for hepatocytes by introducing micropathways within the BAL’s cellular space [3–5]. The current study investigates the benefits of increasing O2 availability of the flow medium via perfluorocarbons (PFCs). PFCs were chosen since they have demonstrated effectiveness in increasing the overall oxygen solubility of their carrier liquids, e.g., artificial blood [2]. The study seeks to clarify the effects of PFCs on hepatocyte viability and functional performance under various culture conditions.

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Rapporti di organizzazioni sul tema "Oxygen (O2)"

Andersson, Anders D., and Xiang-Yang Liu. Oxygen diffusion in UO2+x and (U,Pu)O2+-x. Office of Scientific and Technical Information (OSTI), May 2012. http://dx.doi.org/10.2172/1040018.

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Zhou, James. O2 Binding Materials and highly Efficient Modular System for Oxygen Production. Office of Scientific and Technical Information (OSTI), November 2019. http://dx.doi.org/10.2172/1578151.

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Factory, Fish. Evaluation of Pure Oxygen Systems at the Umatilla Hatchery: Task 1-Review and Evaluation of Supplemental O2 Systems, Final Report. Office of Scientific and Technical Information (OSTI), March 1991. http://dx.doi.org/10.2172/753986.

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