Sample records for high oxygen levels
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High oxygen levels promote peel spotting in banana fruit
Maneenuam, T.; Ketsa, S.; Doorn, van W.G.
2007-01-01
We studied the effect of high oxygen on early peel spotting in `Sucrier¿ bananas held at 25 °C and 90% RH. Fruit first ripened to colour index 3¿4 (about as yellow as green) and were then held in containers with a continuous gas flow of 18 ± 2 kPa (control) or 90 ± 2 kPa oxygen. High oxygen promoted
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Burning of forest materials under late Paleozoic high atmospheric oxygen levels
Richard A., Jr. Wildman; Leo J. Hickey; Matthew B. Dickinson; Robert A. Berner; Jennifer M. Robinson; Michael Dietrich; Robert H. Essenhigh; Craig B. Wildman
2004-01-01
Theoretical models suggest that atmospheric oxygen reached concentrations as high as 35% O2 during the past 550 m.y. Previous burning experiments using strips of paper have challenged this idea, concluding that ancient wildfires would have decimated plant life if O2 significantly exceeded its present level of 21%. New...
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Effects of anesthetic agents on brain blood oxygenation level revealed with ultra-high field MRI
International Nuclear Information System (INIS)
Ciobanu, Luisa; Reynaud, Olivier; Le Bihan, Denis; Uhrig, Lynn; Jarraya, Bechir
2012-01-01
During general anesthesia it is crucial to control systemic hemodynamics and oxygenation levels. However, anesthetic agents can affect cerebral hemodynamics and metabolism in a drug-dependent manner, while systemic hemodynamics is stable. Brain-wide monitoring of this effect remains highly challenging. Because T2'*-weighted imaging at ultra-high magnetic field strengths benefits from a dramatic increase in contrast to noise ratio, we hypothesized that it could monitor anesthesia effects on brain blood oxygenation. We scanned rat brains at 7 T and 17.2 T under general anesthesia using different anesthetics (isoflurane, ketamine-xylazine, medetomidine). We showed that the brain/vessels contrast in T2'*- weighted images at 17.2 T varied directly according to the applied pharmacological anesthetic agent, a phenomenon that was visible, but to a much smaller extent at 7 T. This variation is in agreement with the mechanism of action of these agents. These data demonstrate that preclinical ultra-high field MRI can monitor the effects of a given drug on brain blood oxygenation level in the absence of systemic blood oxygenation changes and of any neural stimulation. (authors)
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Effects of anesthetic agents on brain blood oxygenation level revealed with ultra-high field MRI.
Directory of Open Access Journals (Sweden)
Luisa Ciobanu
Full Text Available During general anesthesia it is crucial to control systemic hemodynamics and oxygenation levels. However, anesthetic agents can affect cerebral hemodynamics and metabolism in a drug-dependent manner, while systemic hemodynamics is stable. Brain-wide monitoring of this effect remains highly challenging. Because T(2*-weighted imaging at ultra-high magnetic field strengths benefits from a dramatic increase in contrast to noise ratio, we hypothesized that it could monitor anesthesia effects on brain blood oxygenation. We scanned rat brains at 7T and 17.2T under general anesthesia using different anesthetics (isoflurane, ketamine-xylazine, medetomidine. We showed that the brain/vessels contrast in T(2*-weighted images at 17.2T varied directly according to the applied pharmacological anesthetic agent, a phenomenon that was visible, but to a much smaller extent at 7T. This variation is in agreement with the mechanism of action of these agents. These data demonstrate that preclinical ultra-high field MRI can monitor the effects of a given drug on brain blood oxygenation level in the absence of systemic blood oxygenation changes and of any neural stimulation.
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Price, Michael; Heilbrun, Lance; Kessel, David
2013-01-01
We examined the effect of the oxygenation level on efficacy of two photosensitizing agents, both of which target lysosomes for photodamage, but via different photochemical pathways. Upon irradiation, the chlorin termed NPe6 forms singlet oxygen in high yield while the bacteriopheophorbide WST11 forms only oxygen radicals (in an aqueous environment). Photokilling efficacy by WST11 in cell culture was impaired when the atmospheric oxygen concentration was reduced from 20% to 1%, while photokilling by NPe6 was unaffected. Studies in a cell-free system revealed that the rates of photobleaching of these agents, as a function of the oxygenation level, were correlated with results described above. Moreover, the rate of formation of oxygen radicals by either agent was more sensitive to the level of oxygenation than was singlet oxygen formation by NPe6. These data indicate that the photochemical process that leads to oxygen radical formation is more dependent on the oxygenation level than is the pathway leading to formation of singlet oxygen. © 2013 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2013 The American Society of Photobiology.
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Low oxygen level increases proliferation and metabolic changes in bovine granulosa cells.
Shiratsuki, Shogo; Hara, Tomotaka; Munakata, Yasuhisa; Shirasuna, Koumei; Kuwayama, Takehito; Iwata, Hisataka
2016-12-05
The present study addresses molecular backgrounds underlying low oxygen induced metabolic changes and 1.2-fold change in bovine granulosa cell (GCs) proliferation. RNA-seq revealed that low oxygen (5%) upregulated genes associated with HIF-1 and glycolysis and downregulated genes associated with mitochondrial respiration than that in high oxygen level (21%). Low oxygen level induced high glycolytic activity and low mitochondrial function and biogenesis. Low oxygen level enhanced GC proliferation with high expression levels of HIF-1, VEGF, AKT, mTOR, and S6RP, whereas addition of anti-VEGF antibody decreased cellular proliferation with low phosphorylated AKT and mTOR expression levels. Low oxygen level reduced SIRT1, whereas activation of SIRT1 by resveratrol increased mitochondrial replication and decreased cellular proliferation with reduction of phosphorylated mTOR. These results suggest that low oxygen level stimulates the HIF1-VEGF-AKT-mTOR pathway and up-regulates glycolysis, which contributes to GC proliferation, and downregulation of SIRT1 contributes to hypoxia-associated reduction of mitochondria and cellular proliferation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
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Price, Michael; Heilbrun, Lance; Kessel, David
2013-01-01
We examined the effect of the oxygenation level on efficacy of two photosensitizing agents, both of which target lysosomes for photodamage but via different photochemical pathways. Upon irradiation, the chlorin termed NPe6 forms singlet oxygen in high yield while the bacteriopheophorbide WST11 forms only oxygen radicals (in an aqueous environment). Photokilling efficacy by WST11 in cell culture was impaired when the atmospheric oxygen concentration was reduced from 20% to 1%, while photokilli...
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Anaerobic nitrogen turnover by sinking diatom aggregates at varying ambient oxygen levels
DEFF Research Database (Denmark)
Stief, Peter; Kamp, Anja; Thamdrup, Bo
2016-01-01
nitrate supply. Sinking diatom aggregates can contribute directly to fixed-nitrogen loss in low-oxygen environments in the ocean and vastly expand the ocean volume in which anaerobic nitrogen turnover is possible, despite relatively high ambient oxygen levels. Depending on the extent of intracellular......In the world’s oceans, even relatively low oxygen levels inhibit anaerobic nitrogen cycling by free-living microbes. Sinking organic aggregates, however, might provide oxygen-depleted microbial hotspots in otherwise oxygenated surface waters. Here, we show that sinking diatom aggregates can host...
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Oxygen tension level and human viral infections
Energy Technology Data Exchange (ETDEWEB)
Morinet, Frédéric, E-mail: frederic.morinet@sls.aphp.fr [Centre des Innovations Thérapeutiques en Oncologie et Hématologie (CITOH), CHU Saint-Louis, Paris (France); Université Denis Diderot, Sorbonne Paris Cité Paris, Paris (France); Casetti, Luana [Institut Cochin INSERM U1016, Paris (France); François, Jean-Hugues; Capron, Claude [Institut Cochin INSERM U1016, Paris (France); Laboratoire d' Hématologie, Hôpital Ambroise Paré, Boulogne (France); Université de Versailles Saint-Quentin en Yvelynes, Versailles (France); Pillet, Sylvie [Laboratoire de Bactériologie-Virologie-Hygiène, CHU de Saint-Etienne, Saint-Etienne (France); Université de Lyon et Université de Saint-Etienne, Jean Monnet, GIMAP EA3064, F-42023 Saint-Etienne, Lyon (France)
2013-09-15
The role of oxygen tension level is a well-known phenomenon that has been studied in oncology and radiotherapy since about 60 years. Oxygen tension may inhibit or stimulate propagation of viruses in vitro as well as in vivo. In turn modulating oxygen metabolism may constitute a novel approach to treat viral infections as an adjuvant therapy. The major transcription factor which regulates oxygen tension level is hypoxia-inducible factor-1 alpha (HIF-1α). Down-regulating the expression of HIF-1α is a possible method in the treatment of chronic viral infection such as human immunodeficiency virus infection, chronic hepatitis B and C viral infections and Kaposi sarcoma in addition to classic chemotherapy. The aim of this review is to supply an updating concerning the influence of oxygen tension level in human viral infections and to evoke possible new therapeutic strategies regarding this environmental condition. - Highlights: • Oxygen tension level regulates viral replication in vitro and possibly in vivo. • Hypoxia-inducible factor 1 (HIF-1α) is the principal factor involved in Oxygen tension level. • HIF-1α upregulates gene expression for example of HIV, JC and Kaposi sarcoma viruses. • In addition to classical chemotherapy inhibition of HIF-1α may constitute a new track to treat human viral infections.
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A theoretical model for oxygen transport in skeletal muscle under conditions of high oxygen demand.
McGuire, B J; Secomb, T W
2001-11-01
Oxygen transport from capillaries to exercising skeletal muscle is studied by use of a Krogh-type cylinder model. The goal is to predict oxygen consumption under conditions of high demand, on the basis of a consideration of transport processes occurring at the microvascular level. Effects of the decline in oxygen content of blood flowing along capillaries, intravascular resistance to oxygen diffusion, and myoglobin-facilitated diffusion are included. Parameter values are based on human skeletal muscle. The dependence of oxygen consumption on oxygen demand, perfusion, and capillary density are examined. When demand is moderate, the tissue is well oxygenated and consumption is slightly less than demand. When demand is high, capillary oxygen content declines rapidly with axial distance and radial oxygen transport is limited by diffusion resistance within the capillary and the tissue. Under these conditions, much of the tissue is hypoxic, consumption is substantially less than demand, and consumption is strongly dependent on capillary density. Predicted consumption rates are comparable with experimentally observed maximal rates of oxygen consumption.
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Inhibition of fungal growth with extreme low oxygen levels
DEFF Research Database (Denmark)
Nielsen, Per Væggemose; Haasum, Iben
1998-01-01
Fungal spoilage of foods is effectively controlled by removal of oxygen from the package, especially if this is combined with elevated carbon dioxide (CO2) levels. However, great uncertainty exist on just how low the residual oxygen levels in the package must be especially when carbon dioxide lev...... food with low CO2 levels. Active packaging with oxygen absorbers may be considered for these products. The packaging solution must also reflect the micro flora of the product.......Fungal spoilage of foods is effectively controlled by removal of oxygen from the package, especially if this is combined with elevated carbon dioxide (CO2) levels. However, great uncertainty exist on just how low the residual oxygen levels in the package must be especially when carbon dioxide...... Penicillia and Aspergilli were also inhibited by oxygen levels less than 0.5%, but less than 0.01% was required to efficiently inhibit these fungi. Most resistant to very low oxygen levels was the Fusarium species.These results shows that very low oxygen levels are required to avoid fungal growth in package...
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The Complex Transcriptional Response of Acaryochloris marina to Different Oxygen Levels
Directory of Open Access Journals (Sweden)
Miguel A. Hernández-Prieto
2017-02-01
Full Text Available Ancient oxygenic photosynthetic prokaryotes produced oxygen as a waste product, but existed for a long time under an oxygen-free (anoxic atmosphere, before an oxic atmosphere emerged. The change in oxygen levels in the atmosphere influenced the chemistry and structure of many enzymes that contained prosthetic groups that were inactivated by oxygen. In the genome of Acaryochloris marina, multiple gene copies exist for proteins that are normally encoded by a single gene copy in other cyanobacteria. Using high throughput RNA sequencing to profile transcriptome responses from cells grown under microoxic and hyperoxic conditions, we detected 8446 transcripts out of the 8462 annotated genes in the Cyanobase database. Two-thirds of the 50 most abundant transcripts are key proteins in photosynthesis. Microoxic conditions negatively affected the levels of expression of genes encoding photosynthetic complexes, with the exception of some subunits. In addition to the known regulation of the multiple copies of psbA, we detected a similar transcriptional pattern for psbJ and psbU, which might play a key role in the altered components of photosystem II. Furthermore, regulation of genes encoding proteins important for reactive oxygen species-scavenging is discussed at genome level, including, for the first time, specific small RNAs having possible regulatory roles under varying oxygen levels.
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The Complex Transcriptional Response of Acaryochloris marina to Different Oxygen Levels
Hernández-Prieto, Miguel A.; Lin, Yuankui; Chen, Min
2016-01-01
Ancient oxygenic photosynthetic prokaryotes produced oxygen as a waste product, but existed for a long time under an oxygen-free (anoxic) atmosphere, before an oxic atmosphere emerged. The change in oxygen levels in the atmosphere influenced the chemistry and structure of many enzymes that contained prosthetic groups that were inactivated by oxygen. In the genome of Acaryochloris marina, multiple gene copies exist for proteins that are normally encoded by a single gene copy in other cyanobacteria. Using high throughput RNA sequencing to profile transcriptome responses from cells grown under microoxic and hyperoxic conditions, we detected 8446 transcripts out of the 8462 annotated genes in the Cyanobase database. Two-thirds of the 50 most abundant transcripts are key proteins in photosynthesis. Microoxic conditions negatively affected the levels of expression of genes encoding photosynthetic complexes, with the exception of some subunits. In addition to the known regulation of the multiple copies of psbA, we detected a similar transcriptional pattern for psbJ and psbU, which might play a key role in the altered components of photosystem II. Furthermore, regulation of genes encoding proteins important for reactive oxygen species-scavenging is discussed at genome level, including, for the first time, specific small RNAs having possible regulatory roles under varying oxygen levels. PMID:27974439
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Fuel cell serves as oxygen level detector
1965-01-01
Monitoring the oxygen level in the air is accomplished by a fuel cell detector whose voltage output is proportional to the partial pressure of oxygen in the sampled gas. The relationship between output voltage and partial pressure of oxygen can be calibrated.
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Wang, Lin; Acosta, Miguel A; Leach, Jennie B; Carrier, Rebecca L
2013-04-21
Capability of measuring and monitoring local oxygen concentration at the single cell level (tens of microns scale) is often desirable but difficult to achieve in cell culture. In this study, biocompatible oxygen sensing beads were prepared and tested for their potential for real-time monitoring and mapping of local oxygen concentration in 3D micro-patterned cell culture systems. Each oxygen sensing bead is composed of a silica core loaded with both an oxygen sensitive Ru(Ph2phen3)Cl2 dye and oxygen insensitive Nile blue reference dye, and a poly-dimethylsiloxane (PDMS) shell rendering biocompatibility. Human intestinal epithelial Caco-2 cells were cultivated on a series of PDMS and type I collagen based substrates patterned with micro-well arrays for 3 or 7 days, and then brought into contact with oxygen sensing beads. Using an image analysis algorithm to convert florescence intensity of beads to partial oxygen pressure in the culture system, tens of microns-size oxygen sensing beads enabled the spatial measurement of local oxygen concentration in the microfabricated system. Results generally indicated lower oxygen level inside wells than on top of wells, and local oxygen level dependence on structural features of cell culture surfaces. Interestingly, chemical composition of cell culture substrates also appeared to affect oxygen level, with type-I collagen based cell culture systems having lower oxygen concentration compared to PDMS based cell culture systems. In general, results suggest that oxygen sensing beads can be utilized to achieve real-time and local monitoring of micro-environment oxygen level in 3D microfabricated cell culture systems.
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Jahnke, L.; Klein, H. P.
1979-01-01
A comparative study of the effects of varying levels of oxygen on some of the metabolic functions of the primitive eukaryote, Saccharomyces cerevisiae, has shown that these cells are responsive to very low levels of oxygen: the level of palmitoyl-Co A desaturase was greatly enhanced by only 0.03 vol % oxygen. Similarly, an acetyl-CoA synthetase associated predominantly with anaerobic growth was stimulated by as little as 0.1% oxygen, while an isoenzyme correlated with aerobic growth was maximally active at much higher oxygen levels (greater than 1%). Closely following this latter pattern were three mitochondrial enzymes that attained maximal activity only under atmospheric levels of oxygen.
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The relation between oxygen saturation level and retionopathy of prematurity
Directory of Open Access Journals (Sweden)
Mohammad Gharavi Fard
2016-03-01
Full Text Available Introduction: Oxygen therapy used for preterm infant disease might be associated with oxygen toxicity or oxidative stress. The exact oxygen concentration to control and maintain the arterial oxygen saturation balance is not certainly clear. We aimed to compare the efficacy of higher or lower oxygen saturations on the development of severe retinopathy of prematurity which is a major cause of blindness in preterm neonates. Methods: PubMed was searched for obtaining the relevant articles. A total of seven articles were included after studying the titles, abstracts, and the full text of retrieved articles at initial search. Inclusion criteria were all the English language human clinical randomized controlled trials with no time limitation, which studied the efficacy of low versus high oxygen saturation measured by pulse oximetry in preterm infants.Result: It can be suggested that lower limits of oxygen saturations have higher efficacy at postmesetural age of ≤28 weeks in preterm neonates. This relation has been demonstrated in five large clinical trials including three Boost trials, COT, and Support.Discussion: Applying higher concentrations of oxygen supplementations at mesentural age ≥32 weeks reduced the development of retinopathy of prematurity. Lower concentrations of oxygen saturation decreased the incidence and the development of retinopathy of prematurity in preterm neonates while applied soon after the birth.Conclusions: Targeting levels of oxygen saturation in the low or high range should be performed cautiously with attention to the postmesentural age in preterm infants at the time of starting the procedures.
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High-Energy-Density Metal-Oxygen Batteries: Lithium-Oxygen Batteries vs Sodium-Oxygen Batteries.
Song, Kyeongse; Agyeman, Daniel Adjei; Park, Mihui; Yang, Junghoon; Kang, Yong-Mook
2017-12-01
The development of next-generation energy-storage devices with high power, high energy density, and safety is critical for the success of large-scale energy-storage systems (ESSs), such as electric vehicles. Rechargeable sodium-oxygen (Na-O 2 ) batteries offer a new and promising opportunity for low-cost, high-energy-density, and relatively efficient electrochemical systems. Although the specific energy density of the Na-O 2 battery is lower than that of the lithium-oxygen (Li-O 2 ) battery, the abundance and low cost of sodium resources offer major advantages for its practical application in the near future. However, little has so far been reported regarding the cell chemistry, to explain the rate-limiting parameters and the corresponding low round-trip efficiency and cycle degradation. Consequently, an elucidation of the reaction mechanism is needed for both lithium-oxygen and sodium-oxygen cells. An in-depth understanding of the differences and similarities between Li-O 2 and Na-O 2 battery systems, in terms of thermodynamics and a structural viewpoint, will be meaningful to promote the development of advanced metal-oxygen batteries. State-of-the-art battery design principles for high-energy-density lithium-oxygen and sodium-oxygen batteries are thus reviewed in depth here. Major drawbacks, reaction mechanisms, and recent strategies to improve performance are also summarized. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Zhang, Jiaxing; Zhang, Haiyan; Chen, Ji; Fan, Ming; Gong, Qiyong
2013-01-01
The present study aimed to investigate structural modulation of brain by high level of oxygen during its peak period of development. Voxel-based morphometry analysis of gray matter (GM) and white matter (WM) volumes and Tract-Based Spatial Statistics analysis of WM fractional anisotropy (FA) and mean diffusion (MD) based on MRI images were carried out on 21 Tibetan adolencents (15-18 years), who were born and raised in Qinghai-Tibetan Plateau (2900-4700 m) and have lived at sea level (SL) in the last 4 years. The control group consisted of matched Tibetan adolescents born and raised at high altitude all the time. SL immigrants had increased GM volume in the left insula, left inferior parietal gyrus, and right superior parietal gyrus and decreased GM in the left precentral cortex and multiple sites in cerebellar cortex (left lobule 8, bilateral lobule 6 and crus 1/2). Decreased WM volume was found in the right superior frontal gyrus in SL immigrants. SL immigrants had higher FA and lower MD at multiple sites of WM tracts. Moreover, we detected changes in ventilation and circulation. GM volume in cerebellum lobule 8 positively correlated with diastolic pressure, while GM volume in insula positively correlated vital capacity and hypoxic ventilatory response. Our finding indicate that the structural modulations of GM by high level of oxygen during its peak period of development are related to respiratory and circulatory regulations, while the modulation in WM mainly exhibits an enhancement in myelin maturation.
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Surface core level shifts of clean and oxygen covered Ir(111)
Energy Technology Data Exchange (ETDEWEB)
Bianchi, M; Cassese, D; Cavallin, A; Comin, R; Orlando, F; Postregna, L [Universita degli Studi di Trieste, Via A Valerio 2, 34127, Trieste (Italy); Golfetto, E; Baraldi, A [Dipartimento di Fisica e CENMAT, Universita degli Studi di Trieste, Via A Valerio 2, 34127, Trieste (Italy); Lizzit, S [Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34012 Trieste (Italy)], E-mail: alessandro.baraldi@elettra.trieste.it
2009-06-15
We present the results of high resolution core level photoelectron spectroscopy employed to investigate the electronic structure of clean and oxygen covered Ir(111) surface. Ir 4f{sub 7/2} core level spectra are shown to be very sensitive to the local atomic environment. For the clean surface we detected two distinct components shifted by 550 meV, originated by surface and bulk atoms. The larger Gaussian width of the bulk component is explained as due to experimentally unresolved subsurface components. In order to determine the relevance of the phonon contribution we examined the thermal behaviour of the core level lineshape using the Hedin-Rosengren theory. From the phonon-induced spectral broadening we found the Debye temperature of bulk and surface atoms to be 298 and 181 K, respectively, which confirms the softening of the vibrational modes at the surface. Oxygen adsorption leads to the appearance of new surface core level components at -200 meV and +230 meV, which are interpreted as due to first-layer Ir atoms differently coordinated with oxygen. The coverage dependence of these components demonstrates that the oxygen saturation corresponds to 0.38 ML, in good agreement with recent density functional theory calculations.
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Energy Technology Data Exchange (ETDEWEB)
Gladys, M.J.; Ermanoski, I.; Jackson, G.; Quinton, J.S.; Rowe, J.E.; Madey, T.E. E-mail: madey@physics.rutgers.edu
2004-04-01
High resolution soft X-ray photoemission electron spectroscopy (SXPS), using synchrotron radiation, is employed to investigate 4f core-level features of four differently-prepared Ir(2 1 0) surfaces: clean planar, oxygen-covered planar, oxygen-induced faceted, and clean faceted surfaces. Surface and bulk peak identifications are supported by measurements at different photon energies (thus probing different electron escape depths) and variable emission angles. Iridium 4f{sub 7/2} photoemission spectra are fitted with Doniach-Sunjic lineshapes. The surface components are identified with core levels positioned at lower binding energies than the bulk components, in contrast to previous reports of binding energy inversion on Ir(1 0 0) (1x1) and (5x1) surfaces. For clean planar Ir(2 1 0) three surface Ir 4f{sub 7/2} features are observed with core-level shifts of -765, -529, and -281 meV, with respect to the bulk; these are associated with the first, second and third layers of atoms, respectively, for atomically rough Ir(2 1 0). Adsorption of oxygen onto the planar Ir(2 1 0) surface is found to cause a suppression and shift of the surface features to higher binding energies. Annealing at T{>=}600 K in oxygen produces a faceted surface as verified by low energy electron diffraction (LEED). A comparison of planar and faceted oxygen-covered surfaces reveals minor differences in the normal emission SXPS spectra, while grazing emission spectra exhibit differences. The SXPS spectrum of the clean, faceted Ir(2 1 0) exhibits small differences in comparison to the clean planar case, with surface features having binding energy shifts of -710, -450, and -230 meV.
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International Nuclear Information System (INIS)
Wagatsuma, Kazuaki
2015-01-01
This paper describes several interesting excitation phenomena occurring in a microwave-induced plasma (MIP) excited with Okamoto-cavity, especially when a small amount of oxygen was mixed with nitrogen matrix in the composition of the plasma gas. An ion-to-atom ratio of iron, which was estimated from the intensity ratio of ion to atomic lines having almost the same excitation energy, was reduced by adding oxygen gas to the nitrogen MIP, eventually contributing to an enhancement in the emission intensities of the atomic lines. Furthermore, Boltzmann plots for iron atomic lines were observed in a wide range of the excitation energy from 3.4 to 6.9 eV, indicating that plots of the atomic lines having lower excitation energies (3.4 to 4.8 eV) were well fitted on a straight line while those having more than 5.5 eV deviated upwards from the linear relationship. This overpopulation would result from any other excitation process in addition to the thermal excitation that principally determines the Boltzmann distribution. A Penning-type collision with excited species of nitrogen molecules probably explains this additional excitation mechanism, in which the resulting iron ions recombine with captured electrons, followed by cascade de-excitations between closely-spaced excited levels just below the ionization limit. As a result, these high-lying levels might be more populated than the low-lying levels of iron atom. The ionization of iron would be caused less actively in the nitrogen–oxygen plasma than in a pure nitrogen plasma, because excited species of nitrogen molecule, which can provide the ionization energy in a collision with iron atom, are consumed through collisions with oxygen molecules to cause their dissociation. It was also observed that the overpopulation occurred to a lesser extent when oxygen gas was added to the nitrogen plasma. The reason for this was also attributed to decreased number density of the excited nitrogen species due to collisions with oxygen
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Ketogenic diet for high partial pressure oxygen diving.
Valadao, Jason M; Vigilante, John A; DiGeorge, Nicholas W; O'Connor, Sunila E; Bear, Alexandria; Kenyon, Jeffrey; Annis, Heather; Dituri, Joseph; Dituri, Amy E; Whelan, Harry T
2014-01-01
A ketogenic diet (KD) may decrease central nervous system oxygen toxicity symptoms in divers, and in view of this implication a feasibility/ toxicity pilot study was performed to demonstrate tolerance of KD while performing normal diving profiles. The exact mechanism of neuroprotection from the KD remains unknown; however, evidence to support the efficacy of the KD in reducing seizures is present in epilepsy and oxygen toxicity studies, and may provide valuable insight in diving activities. Three divers (two males and one female ages 32-45 with a history of deep diving and high pO2 exposure) on the KD made dives to varying depths in Hawaii using fully closed-circuit MK-15 and Inspiration rebreathers. These rebreathers have an electronically controlled set point, allowing the divers to monitor and control the oxygen level in the breathing loop, which can be varied manually by the divers. Oxygen level was varied during descent, bottom depth and ascent (decompression). Divers fasted for 12-18 hours before diet initiation. The ketosis level was verified by urinating on a Ketostix (reagent strips for urinalysis). Ketosis was achieved and was easily monitored with Ketostix in the simulated operational environment. The KD did not interfere with the diving mission; no seizure activity or signs or symptoms of CNS toxicity were observed, and there were no adverse effects noted by the divers while on the KD.
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Hydrogen peroxide production is affected by oxygen levels in mammalian cell culture.
Maddalena, Lucas A; Selim, Shehab M; Fonseca, Joao; Messner, Holt; McGowan, Shannon; Stuart, Jeffrey A
2017-11-04
Although oxygen levels in the extracellular space of most mammalian tissues are just a few percent, under standard cell culture conditions they are not regulated and are often substantially higher. Some cellular sources of reactive oxygen species, like NADPH oxidase 4, are sensitive to oxygen levels in the range between 'normal' physiological (typically 1-5%) and standard cell culture (up to 18%). Hydrogen peroxide in particular participates in signal transduction pathways via protein redox modifications, so the potential increase in its production under standard cell culture conditions is important to understand. We measured the rates of cellular hydrogen peroxide production in some common cell lines, including C2C12, PC-3, HeLa, SH-SY5Y, MCF-7, and mouse embryonic fibroblasts (MEFs) maintained at 18% or 5% oxygen. In all instances the rate of hydrogen peroxide production by these cells was significantly greater at 18% oxygen than at 5%. The increase in hydrogen peroxide production at higher oxygen levels was either abolished or substantially reduced by treatment with GKT 137831, a selective inhibitor of NADPH oxidase subunits 1 and 4. These data indicate that oxygen levels experienced by cells in culture influence hydrogen peroxide production via NADPH oxidase 1/4, highlighting the importance of regulating oxygen levels in culture near physiological values. However, we measured pericellular oxygen levels adjacent to cell monolayers under a variety of conditions and with different cell lines and found that, particularly when growing at 5% incubator oxygen levels, pericellular oxygen was often lower and variable. Together, these observations indicate the importance, and difficulty, of regulating oxygen levels experienced by cells in culture. Copyright © 2017 Elsevier Inc. All rights reserved.
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Pulsating potentiometric titration technique for assay of dissolved oxygen in water at trace level.
Sahoo, P; Ananthanarayanan, R; Malathi, N; Rajiniganth, M P; Murali, N; Swaminathan, P
2010-06-11
A simple but high performance potentiometric titration technique using pulsating sensors has been developed for assay of dissolved oxygen (DO) in water samples down to 10.0 microg L(-1) levels. The technique involves Winkler titration chemistry, commonly used for determination of dissolved oxygen in water at mg L(-1) levels, with modification in methodology for accurate detection of end point even at 10.0 microg L(-1) levels DO present in the sample. An indigenously built sampling cum pretreatment vessel has been deployed for collection and chemical fixing of dissolved oxygen in water samples from flowing water line without exposure to air. A potentiometric titration facility using pulsating sensors developed in-house is used to carry out titration. The power of the titration technique has been realised in estimation of very dilute solution of iodine equivalent to 10 microg L(-1) O(2). Finally, several water samples containing dissolved oxygen from mg L(-1) to microg L(-1) levels were successfully analysed with excellent reproducibility using this new technique. The precision in measurement of DO in water at 10 microg L(-1) O(2) level is 0.14 (n=5), RSD: 1.4%. Probably for the first time a potentiometric titration technique has been successfully deployed for assay of dissolved oxygen in water samples at 10 microg L(-1) levels. Copyright 2010 Elsevier B.V. All rights reserved.
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Pulsating potentiometric titration technique for assay of dissolved oxygen in water at trace level
International Nuclear Information System (INIS)
Sahoo, P.; Ananthanarayanan, R.; Malathi, N.; Rajiniganth, M.P.; Murali, N.; Swaminathan, P.
2010-01-01
A simple but high performance potentiometric titration technique using pulsating sensors has been developed for assay of dissolved oxygen (DO) in water samples down to 10.0 μg L -1 levels. The technique involves Winkler titration chemistry, commonly used for determination of dissolved oxygen in water at mg L -1 levels, with modification in methodology for accurate detection of end point even at 10.0 μg L -1 levels DO present in the sample. An indigenously built sampling cum pretreatment vessel has been deployed for collection and chemical fixing of dissolved oxygen in water samples from flowing water line without exposure to air. A potentiometric titration facility using pulsating sensors developed in-house is used to carry out titration. The power of the titration technique has been realised in estimation of very dilute solution of iodine equivalent to 10 μg L -1 O 2 . Finally, several water samples containing dissolved oxygen from mg L -1 to μg L -1 levels were successfully analysed with excellent reproducibility using this new technique. The precision in measurement of DO in water at 10 μg L -1 O 2 level is 0.14 (n = 5), RSD: 1.4%. Probably for the first time a potentiometric titration technique has been successfully deployed for assay of dissolved oxygen in water samples at 10 μg L -1 levels.
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Wang, Lin; Acosta, Miguel A.; Leach, Jennie B.; Carrier, Rebecca L.
2013-01-01
Capability of measuring and monitoring local oxygen concentration at the single cell level (tens of microns scale) is often desirable but difficult to achieve in cell culture. In this study, biocompatible oxygen sensing beads were prepared and tested for their potential for real-time monitoring and mapping of local oxygen concentration in 3D micro-patterned cell culture systems. Each oxygen sensing bead is composed of a silica core loaded with both an oxygen sensitive Ru(Ph2phen3)Cl2 dye and ...
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Growth of jaguar cichlid (Cichlasoma managuense juveniles at different oxygen levels
Directory of Open Access Journals (Sweden)
Marco Acosta Nassar
2016-03-01
Full Text Available The dependence of growth on the disolved oxygen level was analyzed in juveniles of the guapote tigre, Cichlasoma managuense, in a recirculated system. The guapote tigre is relatively tolerant to low oxygen levels, averaging only a 17% reduction in growth rate per ppm oxygen in the range between 2 and 5 ppm.
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High Selectivity Oxygen Delignification
Energy Technology Data Exchange (ETDEWEB)
Arthur J. Ragauskas
2005-09-30
The overall objective of this program was to develop improved extended oxygen delignification (EOD) technologies for current U.S. pulp mill operations. This was accomplished by: (1) Identifying pulping conditions that optimize O and OO performance; (2) Identifying structural features of lignin that enhance reactivity towards EOD of high kappa pulps; (3) Identifying factors minimizing carbohydrate degradation and improve pulp strength of EOD high kappa pulps; (4) Developing a simple, reproducible method of quantifying yield gains from EOD; and (5) Developing process conditions that significantly reduce the capital requirements of EOD while optimizing the yield benefits. Key research outcomes included, demonstrating the use of a mini-O sequence such as (E+O)Dkf:0.05(E+O) or Dkf:0.05(E+O)(E+O) without interstage washing could capture approximately 60% of the delignification efficiency of a conventional O-stage without the major capital requirements associated with an O-stage for conventional SW kraft pulps. The rate of formation and loss of fiber charge during an O-stage stage can be employed to maximize net fiber charge. Optimal fiber charge development and delignification are two independent parameters and do not parallel each other. It is possible to utilize an O-stage to enhance overall cellulosic fiber charge of low and high kappa SW kraft pulps which is beneficial for physical strength properties. The application of NIR and multi-variant analysis was developed into a rapid and simple method of determining the yield of pulp from an oxygen delignification stage that has real-world mill applications. A focus point of this program was the demonstration that Kraft pulping conditions and oxygen delignification of high and low-kappa SW and HW pulps are intimately related. Improved physical pulp properties and yield can be delivered by controlling the H-factor and active alkali charge. Low AA softwood kraft pulp with a kappa number 30 has an average improvement of 2% in
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Hydrogen gas alleviates oxygen toxicity by reducing hydroxyl radical levels in PC12 cells.
Directory of Open Access Journals (Sweden)
Junchao Yu
Full Text Available Hyperbaric oxygen (HBO therapy through breathing oxygen at the pressure of above 1 atmosphere absolute (ATA is useful for varieties of clinical conditions, especially hypoxic-ischemic diseases. Because of generation of reactive oxygen species (ROS, breathing oxygen gas at high pressures can cause oxygen toxicity in the central nervous system, leading to multiple neurological dysfunction, which limits the use of HBO therapy. Studies have shown that Hydrogen gas (H2 can diminish oxidative stress and effectively reduce active ROS associated with diseases. However, the effect of H2 on ROS generated from HBO therapy remains unclear. In this study, we investigated the effect of H2 on ROS during HBO therapy using PC12 cells. PC12 cells cultured in medium were exposed to oxygen gas or mixed oxygen gas and H2 at 1 ATA or 5 ATA. Cells viability and oxidation products and ROS were determined. The data showed that H2 promoted the cell viability and inhibited the damage in the cell and mitochondria membrane, reduced the levels of lipid peroxidation and DNA oxidation, and selectively decreased the levels of •OH but not disturbing the levels of O2•-, H2O2, or NO• in PC12 cells during HBO therapy. These results indicated that H2 effectively reduced •OH, protected cells against oxygen toxicity resulting from HBO therapy, and had no effect on other ROS. Our data supported that H2 could be potentially used as an antioxidant during HBO therapy.
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Sheard, Michael A; Ghent, Matthew V; Cabral, Daniel J; Lee, Joanne C; Khankaldyyan, Vazgen; Ji, Lingyun; Wu, Samuel Q; Kang, Min H; Sposto, Richard; Asgharzadeh, Shahab; Reynolds, C Patrick
2015-05-15
Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. Copyright © 2015. Published by Elsevier Inc.
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International Nuclear Information System (INIS)
Guerra-Garcia, J.M.; Garcia-Gomez, J.C.
2005-01-01
Generally, harbours are polluted zones characterised by low values of hydrodynamism and oxygen in the water column and high concentrations of pollutants in sediments. The harbour of Ceuta, North Africa, has an unusual structure; it is located between two bays connected by a channel, which increases the water movement and exchange in the harbour, maintaining moderate oxygen levels in the water-sediment interface. Nevertheless, high concentration of organic matter, nutrients and heavy metals were measured in sediments from this harbour. Under these unusual conditions (high levels of pollution but total saturation of oxygen in the water column) we studied the responses of soft-bottom macrobenthic communities using uni and multivariate analyses. The number of species was similar inside and outside the harbour but the species composition differed between internal and external stations; oxygen levels seem to control the 'quantity' of species whereas pollutants control the 'quality' of them. - A high diversity of benthic animals was found in a polluted harbour where high oxygen levels occurred
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Energy Technology Data Exchange (ETDEWEB)
Sheard, Michael A., E-mail: msheard@chla.usc.edu [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Ghent, Matthew V., E-mail: mattghent@gmail.com [Department of Pathology, Keck School of Medicine, University of Southern California, Health Sciences Campus, Los Angeles, CA 90089 (United States); Cabral, Daniel J., E-mail: dcabral14@gmail.com [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); Lee, Joanne C., E-mail: joannebarnhart@gmail.com [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); Khankaldyyan, Vazgen, E-mail: khangaldian@yahoo.com [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Ji, Lingyun, E-mail: lingyun.ji@med.usc.edu [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Wu, Samuel Q., E-mail: swu@chla.usc.edu [Medical Genetics, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Kang, Min H., E-mail: min.kang@ttuhsc.edu [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); and others
2015-05-15
Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. - Highlights: • Establishing new ALL cell lines in 5% oxygen resulted in higher glycolytic expression and function. • Establishing new ALL cell lines in 5% oxygen resulted in higher proliferation and lower cell death. • The divergent metabolic phenotypes selected in 5% and 20% oxygen are semi-permanent.
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International Nuclear Information System (INIS)
Sheard, Michael A.; Ghent, Matthew V.; Cabral, Daniel J.; Lee, Joanne C.; Khankaldyyan, Vazgen; Ji, Lingyun; Wu, Samuel Q.; Kang, Min H.
2015-01-01
Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. - Highlights: • Establishing new ALL cell lines in 5% oxygen resulted in higher glycolytic expression and function. • Establishing new ALL cell lines in 5% oxygen resulted in higher proliferation and lower cell death. • The divergent metabolic phenotypes selected in 5% and 20% oxygen are semi-permanent
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Deep levels in silicon–oxygen superlattices
International Nuclear Information System (INIS)
Simoen, E; Jayachandran, S; Delabie, A; Caymax, M; Heyns, M
2016-01-01
This work reports on the deep levels observed in Pt/Al 2 O 3 /p-type Si metal-oxide-semiconductor capacitors containing a silicon–oxygen superlattice (SL) by deep-level transient spectroscopy. It is shown that the presence of the SL gives rise to a broad band of hole traps occurring around the silicon mid gap, which is absent in reference samples with a silicon epitaxial layer. In addition, the density of states of the deep layers roughly scales with the number of SL periods for the as-deposited samples. Annealing in a forming gas atmosphere reduces the maximum concentration significantly, while the peak energy position shifts from close-to mid-gap towards the valence band edge. Based on the flat-band voltage shift of the Capacitance–Voltage characteristics it is inferred that positive charge is introduced by the oxygen atomic layers in the SL, indicating the donor nature of the underlying hole traps. In some cases, a minor peak associated with P b dangling bond centers at the Si/SiO 2 interface has been observed as well. (paper)
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Robust high temperature oxygen sensor electrodes
DEFF Research Database (Denmark)
Lund, Anders
Platinum is the most widely used material in high temperature oxygen sensor electrodes. However, platinum is expensive and the platinum electrode may, under certain conditions, suffer from poisoning, which is detrimental for an oxygen sensor. The objective of this thesis is to evaluate electrode...... materials as candidates for robust oxygen sensor electrodes. The present work focuses on characterising the electrochemical properties of a few electrode materials to understand which oxygen electrode processes are limiting for the response time of the sensor electrode. Three types of porous platinum......-Dansensor. The electrochemical properties of the electrodes were characterised by electrochemical impedance spectroscopy (EIS), and the structures were characterised by x-ray diffraction and electron microscopy. At an oxygen partial pressures of 0.2 bar, the response time of the sensor electrode was determined by oxygen...
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Formation of neutrophil extracellular traps under low oxygen level
Directory of Open Access Journals (Sweden)
Katja Branitzki-Heinemann
2016-11-01
Full Text Available Since their discovery, neutrophil extracellular traps (NETs have been characterized as a fundamental host innate immune defense mechanism. Conversely, excessive NET release may have a variety of detrimental consequences for the host. A fine balance between NET formation and elimination is necessary to sustain a protective effect during an infectious challenge. Our own recently published data revealed that stabilization of hypoxia inducible factor 1α (HIF-1α by the iron chelating HIF-1α-agonist desferoxamine or AKB-4924 enhanced the release of phagocyte extracellular traps. Since HIF-1α is a global regulator of the cellular response to low oxygen, we hypothesized that NET formation may be similarly increased under low oxygen conditions. Hypoxia occurs in tissues during infection or inflammation, mostly due to overconsumption of oxygen by pathogens and recruited immune cells. Therefore, experiments were performed to characterize the formation of NETs under hypoxic oxygen conditions compared to normoxia. Human blood-derived neutrophils were isolated and incubated under normoxic (21% oxygen level and compared to hypoxic (1% conditions. Dissolved oxygen levels were monitored in the primary cell culture using a Fibox4-PSt3 measurement system. The formation of NETs was quantified by fluorescence microscopy in response to the known NET-inducer phorbol 12-myristate 13-acetate (PMA or S. aureus wildtype and a nuclease-deficient mutant. In contrast to our hypothesis, spontaneous NET formation of neutrophils incubated under hypoxia was distinctly reduced compared to control neutrophils incubated under normoxia. Furthermore, neutrophils incubated under hypoxia showed significantly reduced formation of NETs in response to PMA. Gene expression analysis revealed that mRNA level of hif-1α as well as hif-1α target genes was not altered. However, in good correlation to the decreased NET formation under hypoxia, the cholesterol content of the neutrophils was
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Kim-Hak, D.; Hoffnagle, J.; Rella, C.; Sun, M.
2016-12-01
Oxygen is a major and vital component of the Earth atmosphere representing about 21% of its composition. It is consumed or produced through biochemical processes such as combustion, respiration, and photosynthesis. Although atmospheric oxygen is not a greenhouse gas, it can be used as a top-down constraint on the carbon cycle. The variation observations of oxygen in the atmosphere are very small, in the order of the few ppm's. This presents the main technical challenge for measurement as a very high level of precision is required and only few methods including mass spectrometry, fuel cell, and paramagnetic are capable of overcoming it. Here we present new developments of a high-precision gas analyzer that utilizes the technique of Cavity Ring-Down Spectroscopy to measure oxygen concentration and oxygen isotope. Its compact and ruggedness design combined with high precision and long-term stability allows the user to deploy the instrument in the field for continuous monitoring of atmospheric oxygen level. Measurements have a 1-σ 5-minute averaging precision of 1-2 ppm for O2 over a dynamic range of 0-20%. We will present supplemental data acquired from our 10m tower measurements in Santa Clara, CA.
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Introduction of high oxygen concentrations into silicon wafers by high-temperature diffusion
International Nuclear Information System (INIS)
Casse, G.; Glaser, M.; Lemeilleur, F.; Ruzin, A.; Wegrzecki, M.
1999-01-01
The tolerance of silicon detectors to hadron irradiation can be improved by the introduction of a high concentration of oxygen into the starting material. High-resistivity Floating-Zone (FZ) silicon is required for detectors used in particle physics applications. A significantly high oxygen concentration (>10 17 atoms cm -3 ) cannot readily be achieved during the FZ silicon refinement. The diffusion of oxygen at elevated temperatures from a SiO 2 layer grown on both sides of a silicon wafer is a simple and effective technique to achieve high and uniform concentrations of oxygen throughout the bulk of a 300 μm thick silicon wafer
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Energy Technology Data Exchange (ETDEWEB)
Maimaitijiang, Alimujiang; Zhuang, Xinyu; Jiang, Xiaofei; Li, Yong, E-mail: 11211220031@fudan.edu.cn
2016-03-18
Hyperproliferation of vascular smooth muscle cells is a pathogenic mechanism common in diabetic vascular complications and is a putatively important therapeutic target. This study investigated multiple levels of biology, including cellular and organellar changes, as well as perturbations in protein synthesis and morphology. Quantitative and qualitative analysis was utilized to assess the effect of mitochondrial dynamic changes and reactive oxygen species(ROS) levels on high-glucose-induced hyperproliferation of vascular smooth muscle cells. The data demonstrated that the mitochondrial fission inhibitor Mdivi-1 and downregulation of ROS levels both effectively inhibited the high-glucose-induced hyperproliferation of vascular smooth muscle cells. Downregulation of ROS levels played a more direct role and ROS levels were also regulated by mitochondrial dynamics. Increased ROS levels induced excessive mitochondrial fission through dynamin-related protein (Drp 1), while Mdivi-1 suppressed the sensitivity of Drp1 to ROS levels, thus inhibiting excessive mitochondrial fission under high-glucose conditions. This study is the first to propose that mitochondrial dynamic changes and ROS levels interact with each other and regulate high-glucose-induced hyperproliferation of vascular smooth muscle cells. This finding provides novel ideas in understanding the pathogenesis of diabetic vascular remodeling and intervention. - Highlights: • Mdivi-1 inhibits VSMC proliferation by lowering ROS level in high-glucose condition. • ROS may be able to induce mitochondrial fission through Drp1 regulation. • Mdivi-1 can suppress the sensitivity of Drp1 to ROS.
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Pancreas Oxygen Persufflation Increases ATP Levels as Shown by Nuclear Magnetic Resonance
Scott, W.E.; Weegman, B.P.; Ferrer-Fabrega, J.; Stein, S.A.; Anazawa, T.; Kirchner, V.A.; Rizzari, M.D.; Stone, J.; Matsumoto, S.; Hammer, B.E.; Balamurugan, A.N.; Kidder, L.S.; Suszynski, T.M.; Avgoustiniatos, E.S.; Stone, S.G.; Tempelman, L.A.; Sutherland, D.E.R.; Hering, B.J.; Papas, K.K.
2010-01-01
Background Islet transplantation is a promising treatment for type 1 diabetes. Due to a shortage of suitable human pancreata, high cost, and the large dose of islets presently required for long-term diabetes reversal; it is important to maximize viable islet yield. Traditional methods of pancreas preservation have been identified as suboptimal due to insufficient oxygenation. Enhanced oxygen delivery is a key area of improvement. In this paper, we explored improved oxygen delivery by persufflation (PSF), ie, vascular gas perfusion. Methods Human pancreata were obtained from brain-dead donors. Porcine pancreata were procured by en bloc viscerectomy from heparinized donation after cardiac death donors and were either preserved by either two-layer method (TLM) or PSF. Following procurement, organs were transported to a 1.5-T magnetic resonance (MR) system for 31P nuclear magnetic resonance spectroscopy to investigate their bioenergetic status by measuring the ratio of adenosine triphosphate to inorganic phosphate (ATP:Pi) and for assessing PSF homogeneity by MRI. Results Human and porcine pancreata can be effectively preserved by PSF. MRI showed that pancreatic tissue was homogeneously filled with gas. TLM can effectively raise ATP:Pi levels in rat pancreata but not in larger porcine pancreata. ATP:Pi levels were almost undetectable in porcine organs preserved with TLM. When human or porcine organs were preserved by PSF, ATP:Pi was elevated to levels similar to those observed in rat pancreata. Conclusion The methods developed for human and porcine pancreas PSF homogeneously deliver oxygen throughout the organ. This elevates ATP levels during preservation and may improve islet isolation outcomes while enabling the use of marginal donors, thus expanding the usable donor pool. PMID:20692395
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Anaerobic Nitrogen Turnover by Sinking Diatom Aggregates at Varying Ambient Oxygen Levels
Directory of Open Access Journals (Sweden)
Peter eStief
2016-02-01
Full Text Available In the world’s oceans, even relatively low oxygen (O2 levels inhibit anaerobic nitrogen cycling by free-living microbes. Sinking organic aggregates, however, might provide oxygen-depleted microbial hotspots in otherwise oxygenated surface waters. Here we show that sinking diatom aggregates can host anaerobic nitrogen cycling at ambient O2 levels well above the hypoxic threshold. Aggregates were produced from the ubiquitous diatom Skeletonema marinoi and the natural microbial community of seawater. Microsensor profiling through the center of sinking aggregates revealed internal anoxia at ambient 40% air saturation (~100 µmol O2 L-1 and below. Accordingly, anaerobic nitrate turnover inside the aggregates was evident within this range of ambient O2 levels. In incubations with 15N-labeled nitrate, individual Skeletonema aggregates produced NO2- (up to 10.7 nmol N h-1 per aggregate, N2 (up to 7.1 nmol N h-1, NH4+ (up to 2.0 nmol N h-1, and N2O (up to 0.2 nmol N h-1. Intriguingly, nitrate stored inside the diatom cells served as an additional, internal nitrate source for N2 production, which may partially uncouple anaerobic nitrate turnover by diatom aggregates from direct ambient nitrate supply. Sinking diatom aggregates can contribute directly to fixed-nitrogen loss in low-oxygen environments in the ocean and vastly expand the ocean volume in which anaerobic nitrogen turnover is possible, despite relatively high ambient O2 levels. Depending on the extent of intracellular nitrate consumption during the sinking process, diatom aggregates may also be involved in the long-distance export of nitrate to the deep ocean.
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Energy Technology Data Exchange (ETDEWEB)
Nissen, Johanna C.; Haneder, Stefan; Schoenberg, Stefan O.; Michaely, Henrik J. [Heidelberg Univ. Medizinische Fakultaet Mannheim (Germany). Inst. fuer Klinische Radiologie und Nuklearmedizin; Mie, Moritz B.; Zoellner, Frank G. [Heidelberg Univ. Medizinische Fakultaet Mannheim (DE). Inst. fuer Computerunterstuetzte Klinische Medizin (CKM)
2010-07-01
Many renal diseases as well as several pharmacons cause a change in renal blood flow and/or renal oxygenation. The blood oxygenation level dependent (BOLD) imaging takes advantage of local field inhomogeneities and is based on a T2{sup *}-weighted sequence. BOLD is a non-invasive method allowing an estimation of the renal, particularly the medullary oxygenation, and an indirect measurement of blood flow without administration of contrast agents. Thus, effects of different drugs on the kidney and various renal diseases can be controlled and observed. This work will provide an overview of the studies carried out so far and identify ways how BOLD can be used in clinical studies. (orig.)
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Oxygen binding properties, capillary densities and heart weights in high altitude camelids.
Jürgens, K D; Pietschmann, M; Yamaguchi, K; Kleinschmidt, T
1988-01-01
The oxygen binding properties of the blood of the camelid species vicuna, llama, alpaca and dromedary camel were measured and evaluated with respect to interspecific differences. The highest blood oxygen affinity, not only among camelids but of all mammals investigated so far, was found in the vicuna (P50 = 17.6 Torr compared to 20.3-21.6 Torr in the other species). Low hematocrits (23-34%) and small red blood cells (21-30 microns 3) are common features of all camelids, but the lowest values are found in the Lama species. Capillary densities were determined in heart and soleus muscle of vicuna and llama. Again, the vicuna shows exceptional values (3720 cap/mm2 on average in the heart) for a mammal of this body size. Finally, heart weight as percent of body weight is higher in the vicuna (0.7-0.9%) than in the other camelids studied (0.5-0.7%). The possibility that these parameters, measured in New World tylopodes at sea level, are not likely to change considerably with transfer to high altitude, is discussed. In the vicuna, a unique combination of the following features seems to be responsible for an outstanding physical capability at high altitude: saturation of blood with oxygen in the lung is favored by a high blood oxygen affinity, oxygen supply being facilitated by low diffusion distances in the muscle tissue. Loading, as well as unloading, of oxygen is improved by a relatively high oxygen transfer conductance of the red blood cells, which is due to their small size and which compensates the negative effect of a low hematocrit on the oxygen conductance of blood.(ABSTRACT TRUNCATED AT 250 WORDS)
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Directory of Open Access Journals (Sweden)
Isaac Cano
Full Text Available The production of reactive oxygen species (ROS from the inner mitochondrial membrane is one of many fundamental processes governing the balance between health and disease. It is well known that ROS are necessary signaling molecules in gene expression, yet when expressed at high levels, ROS may cause oxidative stress and cell damage. Both hypoxia and hyperoxia may alter ROS production by changing mitochondrial Po2 (PmO2. Because PmO2 depends on the balance between O2 transport and utilization, we formulated an integrative mathematical model of O2 transport and utilization in skeletal muscle to predict conditions to cause abnormally high ROS generation. Simulations using data from healthy subjects during maximal exercise at sea level reveal little mitochondrial ROS production. However, altitude triggers high mitochondrial ROS production in muscle regions with high metabolic capacity but limited O2 delivery. This altitude roughly coincides with the highest location of permanent human habitation. Above 25,000 ft., more than 90% of exercising muscle is predicted to produce abnormally high levels of ROS, corresponding to the "death zone" in mountaineering.
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Directory of Open Access Journals (Sweden)
Pål Lagestad
2018-03-01
Full Text Available Several studies have investigated activity levels among adolescents, but no study has examined longitudinal changes in physical activity (PA level, body mass, and oxygen uptake among the same adolescents from the age of 14 to 19 years. The present study examined data from a research project that included a group of randomly selected students (N = 116 with objective measurements of PA (accelerometer data, self-reported PA level, and body mass and oxygen uptake during a 5-year period. The results show a significant decrease in the accelerometer-based PA level over time, from age 14 to 19. At 14 years of age, the minutes of moderate and/or vigorous PA was 66.7 min·day−1, but was less than half, at only 24.4 min·day−1, at 19 years of age. The self-reported activity data show a decrease in girls’ general activity level over time, while boys’ activity level during school breaks decreased strongly during the period: at age 14, 61% of the boys were classified as active, while at age 19, only 11% were physically active. Furthermore, body mass index increased during the period for both genders, while oxygen uptake decreased. Since both BMI and maximal oxygen uptake are important risk factors for future CVD, these findings point toward the importance of maintaining a high activity level during childhood and adolescence, in order to keep fit later in life.
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NOx emissions from high swirl turbulent spray flames with highly oxygenated fuels
Bohon, Myles
2013-01-01
Combustion of fuels with fuel bound oxygen is of interest from both a practical and a fundamental viewpoint. While a great deal of work has been done studying the effect of oxygenated additives in diesel and gasoline engines, much less has been done examining combustion characteristics of fuels with extremely high mass fractions of fuel bound oxygen. This work presents an initial investigation into the very low NOx emissions resulting from the combustion of a model, high oxygen mass fraction fuel. Glycerol was chosen as a model fuel with a fuel bound oxygen mass fraction of 52%, and was compared with emissions measured from diesel combustion at similar conditions in a high swirl turbulent spray flame. This work has shown that high fuel bound oxygen mass fractions allow for combustion at low global equivalence ratios with comparable exhaust gas temperatures due to the significantly lower concentrations of diluting nitrogen. Despite similar exhaust gas temperatures, NOx emissions from glycerol combustion were up to an order of magnitude lower than those measured using diesel fuel. This is shown to be a result not of specific burner geometry, but rather is influenced by the presence of higher oxygen and lower nitrogen concentrations at the flame front inhibiting NOx production. © 2012 The Combustion Institute.
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Liu, Min; Liu, Jingjun; Li, Zhilin; Wang, Feng
2018-02-28
Developing atomic-level transition oxides may be one of the most promising ways for providing ultrahigh electrocatalytic performance for oxygen reduction reaction (ORR), compared with their bulk counterparts. In this article, we developed a set of atomically thick Co 3 O 4 layers covered on Co nanoparticles through partial reduction of Co 3 O 4 nanoparticles using melamine as a reductive additive at an elevated temperature. Compared with the original Co 3 O 4 nanoparticles, the synthesized Co 3 O 4 with a thickness of 1.1 nm exhibits remarkably enhanced ORR activity and durability, which are even higher than those obtained by a commercial Pt/C in an alkaline environment. The superior activity can be attributed to the unique physical and chemical structures of the atomic-level oxide featuring the narrowed band gap and decreased work function, caused by the escaped lattice oxygen and the enriched coordination-unsaturated Co 2+ in this atomic layer. Besides, the outstanding durability of the catalyst can result from the chemically epitaxial deposition of the Co 3 O 4 on the cobalt surface. Therefore, the proposed synthetic strategy may offer a smart way to develop other atomic-level transition metals with high electrocatalytic activity and stability for energy conversion and storage devices.
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Zhu, Hai-tao; Bian, Chen; Yuan, Ji-chao; Liao, Xiao-jun; Liu, Wei; Zhu, Gang; Feng, Hua; Lin, Jiang-kai
2015-06-15
Intracerebral hemorrhage (ICH) at high altitude is not well understood to date. This study investigates the effects of high altitude on ICH, and examines the acute neuroprotection of hyperbaric oxygen (HBO) therapy against high-altitude ICH. Minipigs were placed in a hypobaric chamber for 72 h before the operation. ICH was induced by an infusion of autologous arterial blood (3 ml) into the right basal ganglia. Animals in the high-altitude ICH group received HBO therapy (2.5 ATA for 60 min) 30 min after ICH. Blood gas, blood glucose and brain tissue oxygen partial pressure (PbtO2) were monitored continuously for animals from all groups, as were microdialysis products including glucose, lactate, pyruvate and glutamate in perihematomal tissue from 3 to 12 h post-ICH. High-altitude ICH animals showed significantly lower PbtO2, higher lactate/pyruvate ratio (LPR) and glutamate levels than low-altitude ICH animals. More severe neurological deficits, brain edema and neuronal damage were also observed in high-altitude ICH. After HBO therapy, PbtO2 was significantly increased and LPR and glutamate levels were significantly decreased. Brain edema, neurological deficits and neuronal damage were also ameliorated. The data suggested a more serious disturbance of tissue oxygenation and cerebral metabolism in the acute stage after ICH at high altitude. Early HBO treatment reduced acute brain injury, perhaps through a mechanism involving the amelioration of the derangement of cerebral oxygenation and metabolism following high-altitude ICH.
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Are macroinvertebrates in high altitude streams affected by oxygen deficiency?
DEFF Research Database (Denmark)
Jacobsen, Dean; Rostgaard, S.; Vásconez, J. J.
2003-01-01
1. The solubility of oxygen in water increases with decreasing temperature. This has led to a general perception of cold, high mountain streams as more oxygen rich than warmer lowland streams, and that macroinvertebrates inhabiting high altitude streams have had no need to adapt to critical oxygen...... conditions. However, this fails to take into account that oxygen solubility declines with decreasing atmospheric pressure, which may be of importance at high altitudes. 2. Based on samples of macroinvertebrate benthos and in situ measurements of respiratory oxygen demand of macroinvertebrates in small...... the mean weight-specific respiratory rate of macroinvertebrates declined by only 50%, from 400 to 3800 m. We suggest that this disproportionately large gap between availability and demand of oxygen at high altitudes may imply a potential oxygen deficiency for the fauna, and we discuss how oxygen deficiency...
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Wang, Pengbo; Sun, Jiajing; Meng, Lingkang; Li, Zebin; Li, Ting
2018-02-01
Low level light/laser therapy (LLLT) is considered as a novel, non-invasive, and potential therapy in a variety of psychological and physical conditions, due to its effective intricate photobiomodulation. The mechanism of LLLT is that when cells are stimulated by photons, mitochondria produce a large quantity of ATP, which accelerates biochemical responses in the cell. It is of great significance to gain a clear insight into the change or interplay of various physiological parameters. In this study, we used functional near-infrared spectroscopy (fNIRS) and venous-occlusion plethysmography to measure the LLLT-induced changes in blood flow, oxygenation, and oxygen consumption in human forearms in vivo. Six healthy human participants (4 males and 2 females) were administered with 810-nm light emitted by LED array in ten minutes and blood flow, oxygenation and oxygen consumption were detected in the entire experiment. We found that LLLT induced an increase of blood flow and oxygen consumption on the treated site. Meanwhile, LLLT took a good role in promoting oxygenation of regional tissue, which was indicated by a significant increase of oxygenated hemoglobin concentration (Δ[HbO2]), a nearly invariable deoxygenated hemoglobin concentration (Δ[Hb]) and a increase of differential hemoglobin concentration (Δ[HbD] = Δ[HbO2] - Δ[Hb]). These results not only demonstrate enormous potential of LLLT, but help to figure out mechanisms of photobiomodulation.
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Directory of Open Access Journals (Sweden)
Farhatul Inayah Adiputri
2016-03-01
Full Text Available Background: Hemoglobin and hematocrit levels increase in Tetralogy of Fallot (TOF but the oxygen saturation declines. Reduced hemoglobin in circulating blood as a parameter of cyanosis does not indicate rising hemoglobin due to the ‘not-working’ hemoglobins that affect the oxygen saturation. Increasing hematocrit is the result of secondary erythrocytosis caused by declining oxygen level in blood, which is related to the oxygen saturation. This study was conducted to find the correlation between oxygen saturation and hemoglobin and hematocrite levels in TOF patients. Methods: This study was undertaken at Dr. Hasan Sadikin General Hospital in the period of January 2011 to December 2012 using the cross-sectional analytic method with total sampling technique. Inclusion criteria were medical records of TOF patients diagnosed based on echocardiography that included data on oxygen saturation, hemoglobin, and hematocrite. Exclusion criteria was the history of red blood transfusion. Results: Thirty medical records of TOF patiens from Dr. Hasan Sadikin General Hospital Bandung were included in this study. Due to skewed data distribution, Spearman correlation test was used to analyze the data. There was a significant negative correlation between oxygen saturation and hematocrit level (r= -0.412; p=0.024 and insignificant correlation between oxygen saturation and hemoglobin (r=-0.329; p= 0.076. Conclusions: There is a weak negative correlation between oxygen saturation and hematocrite levels
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Measurement and interpretation of low levels of dissolved oxygen in ground water
White, A.F.; Peterson, M.L.; Solbau, R.D.
1990-01-01
A Rhodazine-D colorimetric technique was adapted to measure low-level dissolved oxygen concentrations in ground water. Prepared samples containing between 0 and 8.0 ??moles L-1 dissolved oxygen in equilibrium with known gas mixtures produced linear spectrophotometric absorbance with a lower detection limit of 0.2 ??moles L-1. Excellent reproducibility was found for solutions ranging in composition from deionized water to sea water with chemical interferences detected only for easily reduced metal species such as ferric ion, cupric ion, and hexavalent chromium. Such effects were correctable based on parallel reaction stoichiometries relative to oxygen. The technique, coupled with a downhole wire line tool, permitted low-level monitoring of dissolved oxygen in wells at the selenium-contaminated Kesterson Reservoir in California. Results indicated a close association between low but measurable dissolved oxygen concentrations and mobility of oxidized forms of selenium. -from Authors
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DEFF Research Database (Denmark)
Randsoe, Thomas; Hyldegaard, Ole
2012-01-01
The standard treatment of altitude decompression sickness (aDCS) caused by nitrogen bubble formation is oxygen breathing and recompression. However, micro air bubbles (containing 79% nitrogen), injected into adipose tissue, grow and stabilize at 25 kPa regardless of continued oxygen breathing...... at 101.3 kPa (sea level) or at 25 kPa altitude exposures during continued oxygen breathing. In keeping with previous observations and bubble kinetic models, we hypothesize that oxygen breathing may contribute to oxygen bubble growth at altitude. Anesthetized rats were exposed to 3 h of oxygen...... prebreathing at 101.3 kPa (sea level). Micro oxygen bubbles of 500-800 nl were then injected into the exposed abdominal adipose tissue. The oxygen bubbles were studied for up to 3.5 h during continued oxygen breathing at either 101.3 or 25 kPa ambient pressures. At 101.3 kPa, all bubbles shrank consistently...
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Oxygen Handling and Cooling Options in High Temperature Electrolysis Plants
Energy Technology Data Exchange (ETDEWEB)
Manohar S. Sohal; J. Stephen Herring
2008-07-01
Idaho National Laboratory is working on a project to generate hydrogen by high temperature electrolysis (HTE). In such an HTE system, safety precautions need to be taken to handle high temperature oxygen at ~830°C. This report is aimed at addressing oxygen handling in a HTE plant.. Though oxygen itself is not flammable, most engineering material, including many gases and liquids, will burn in the presence of oxygen under some favorable physicochemical conditions. At present, an absolute set of rules does not exist that can cover all aspects of oxygen system design, material selection, and operating practices to avoid subtle hazards related to oxygen. Because most materials, including metals, will burn in an oxygen-enriched environment, hazards are always present when using oxygen. Most materials will ignite in an oxygen-enriched environment at a temperature lower than that in air, and once ignited, combustion rates are greater in the oxygen-enriched environment. Even many metals, if ignited, burn violently in an oxygen-enriched environment. However, these hazards do not preclude the operations and systems involving oxygen. Oxygen can be safely handled and used if all the materials in a system are not flammable in the end-use environment or if ignition sources are identified and controlled. In fact, the incidence of oxygen system fires is reported to be low with a probability of about one in a million. This report is a practical guideline and tutorial for the safe operation and handling of gaseous oxygen in high temperature electrolysis system. The intent is to provide safe, practical guidance that permits the accomplishment of experimental operations at INL, while being restrictive enough to prevent personnel endangerment and to provide reasonable facility protection. Adequate guidelines are provided to govern various aspects of oxygen handling associated with high temperature electrolysis system to generate hydrogen. The intent here is to present acceptable
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Directory of Open Access Journals (Sweden)
Sergio Galdames-Maliqueo
2017-12-01
Full Text Available Introduction: The low levels of maximum oxygen consumption (VO2max evaluated in Chilean schoolchildren suggest the startup of trainings that improve the aerobic capacity. Objective: To analyze the effect of a High-intensity Interval Training method on maximum oxygen consumption in Chilean schoolchildren. Materials and methods: Thirty-two high school students from the eighth grade, who were divided into two groups, were part of the study (experimental group = 16 students and control group = 16 students. The main analyzed variable was the maximum oxygen consumption through the Course Navette Test. A High-intensity Interval training method was applied based on the maximum aerobic speed obtained through the Test. A mixed ANOVA was used for statistical analysis. Results: The experimental group showed a significant increase in the Maximum Oxygen Consumption between the pretest and posttest when compared with the control group (p < 0.0001. Conclusion: The results of the study showed a positive effect of the High-intensity Interval Training on the maximum consumption of oxygen. At the end of the study, it is concluded that High-intensity Interval Training is a good stimulation methodology for Chilean schoolchildren.
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Directory of Open Access Journals (Sweden)
Alexis Espinoza Salinas
2014-06-01
Full Text Available Introduction A number of cardiovascular risk factors characterizes the metabolic syndrome: insulin resistance (IR, low HDL cholesterol and high triglycerides. The aforementioned risk factors lead to elevated levels of abdominal adipose tissue, resulting in oxygen consumption deficiency. Purpose To verify the validity and applicability of using high intensity interval training (HIIT in subjects with metabolic syndrome and to answer the following question: Can HIIT improve peak oxygen consumption? Method The systematic review "Effects of aerobic interval training on exercise capacity and metabolic risk factors in individuals with cardiometabolic disorders" was analyzed. Results Data suggests high intensity aerobic interval training increases peak oxygen consumption by a standardized mean difference of 3.60 mL/kg-1/min-1 (95% confidence interval, 0.28-4.91. Conclusion In spite of the methodological shortcomings of the primary studies included in the systematic review, we reasonably conclude that implementation of high intensity aerobic interval training in subjects with metabolic syndrome, leads to increases in peak oxygen consumption.
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Oxygen-Partial-Pressure Sensor for Aircraft Oxygen Mask
Kelly, Mark; Pettit, Donald
2003-01-01
A device that generates an alarm when the partial pressure of oxygen decreases to less than a preset level has been developed to help prevent hypoxia in a pilot or other crewmember of a military or other high-performance aircraft. Loss of oxygen partial pressure can be caused by poor fit of the mask or failure of a hose or other component of an oxygen distribution system. The deleterious physical and mental effects of hypoxia cause the loss of a military aircraft and crew every few years. The device is installed in the crewmember s oxygen mask and is powered via communication wiring already present in all such oxygen masks. The device (see figure) includes an electrochemical sensor, the output potential of which is proportional to the partial pressure of oxygen. The output of the sensor is amplified and fed to the input of a comparator circuit. A reference potential that corresponds to the amplified sensor output at the alarm oxygen-partial-pressure level is fed to the second input of the comparator. When the sensed partial pressure of oxygen falls below the minimum acceptable level, the output of the comparator goes from the low state (a few millivolts) to the high state (near the supply potential, which is typically 6.8 V for microphone power). The switching of the comparator output to the high state triggers a tactile alarm in the form of a vibration in the mask, generated by a small 1.3-Vdc pager motor spinning an eccentric mass at a rate between 8,000 and 10,000 rpm. The sensation of the mask vibrating against the crewmember s nose is very effective at alerting the crewmember, who may already be groggy from hypoxia and is immersed in an environment that is saturated with visual cues and sounds. Indeed, the sensation is one of rudeness, but such rudeness could be what is needed to stimulate the crewmember to take corrective action in a life-threatening situation.
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Bak, Kathrine Holmgaard; Lindahl, Gunilla; Karlsson, Anders H; Lloret, Elsa; Gou, Pere; Arnau, Jacint; Orlien, Vibeke
2013-10-01
Color stability of minced cured restructured ham was studied by considering the effects of high pressure (HP) (600 MPa, 13°C, 5 min), raw meat pH24 (low, normal, high), salt content (15, 30 g/kg), drying (20%, 50% weight loss), and residual oxygen level (0.02%-0.30%). Raw hams were selected by pH24 in Semimembranosus, mixed with additives, frozen, sliced, and dried by the Quick-Dry-Slice® (QDS) process followed by HP treatment or not (control). Packaging and storage simulated industrial packaging: modified atmosphere containing 80% N2, 20% CO2, and residual O2 in one of three intervals: hams, while the stabilizing effect on 50% QDS hams was smaller, concluding that water has the dominating role. Raw meat pH24, salt content, and residual oxygen level had varying effects on the stability of the red color. Copyright © 2013 Elsevier Ltd. All rights reserved.
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Futalan, Diahnn; Huang, Chien-Tze; Schmidt-Wolf, Ingo G H; Larsson, Marie; Messmer, Davorka
2011-01-01
Dendritic cell (DC)-based adoptive tumor immunotherapy approaches have shown promising results, but the incidence of tumor regression is low and there is an evident call for identifying culture conditions that produce DCs with a more potent Th1 potential. Routinely, DCs are differentiated in CO(2) incubators under atmospheric oxygen conditions (21% O(2)), which differ from physiological oxygen levels of only 3-5% in tissue, where most DCs reside. We investigated whether differentiation and maturation of DCs under physiological oxygen levels could produce more potent T-cell stimulatory DCs for use in adoptive immunotherapy. We found that immature DCs differentiated under physiological oxygen levels showed a small but significant reduction in their endocytic capacity. The different oxygen levels did not influence their stimuli-induced upregulation of cluster of differentiation 54 (CD54), CD40, CD83, CD86, C-C chemokine receptor type 7 (CCR7), C-X-C chemokine receptor type 4 (CXCR4) and human leukocyte antigen (HLA)-DR or the secretion of interleukin (IL)-6, tumor necrosis factor (TNF)-α and IL-10 in response to lipopolysaccharide (LPS) or a cytokine cocktail. However, DCs differentiated under physiological oxygen level secreted higher levels of IL-12(p70) after exposure to LPS or CD40 ligand. Immature DCs differentiated at physiological oxygen levels caused increased T-cell proliferation, but no differences were observed for mature DCs with regard to T-cell activation. In conclusion, we show that although DCs generated under atmospheric or physiological oxygen conditions are mostly similar in function and phenotype, DCs differentiated under physiological oxygen secrete larger amounts of IL-12(p70). This result could have implications for the use of ex vivo-generated DCs for clinical studies, since DCs differentiated at physiological oxygen could induce increased Th1 responses in vivo.
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Limitations of potentiometric oxygen sensors operating at low oxygen levels
DEFF Research Database (Denmark)
Lund, Anders; Jacobsen, Torben; Hansen, Karin Vels
2011-01-01
The electrochemical processes that limit the range of oxygen partial pressures in which potentiometric oxygen sensors can be used, were analysed using a theoretical and an experimental approach. Electrochemical impedance spectroscopy was performed on porous Pt/yttria stabilised zirconia (YSZ......) electrodes between 10−6 and 0.2 bar and at temperatures between 500 and 950 °C. The flow of oxide ions and electron holes through a sensor cell, with a YSZ electrolyte, were calculated under similar conditions. The oxygen permeation of the sensor cell was insignificant at an oxygen partial pressure of 10......−6 bar for an inlet flow rate higher than 2 L h−1 between 600 and 800 °C. The polarisation resistance measured between 10−6 and 10−4 bar was found to be inversely proportional to the oxygen partial pressure, nearly temperature independent and inversely proportional to the inlet gas flow rate, which shows...
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Henneberry, Hugh M.; Snyder, Christopher A.
1993-01-01
An analysis of gas turbine engines using water and oxygen injection to enhance performance by increasing Mach number capability and by increasing thrust is described. The liquids are injected, either separately or together, into the subsonic diffuser ahead of the engine compressor. A turbojet engine and a mixed-flow turbofan engine (MFTF) are examined, and in pursuit of maximum thrust, both engines are fitted with afterburners. The results indicate that water injection alone can extend the performance envelope of both engine types by one and one-half Mach numbers at which point water-air ratios reach 17 or 18 percent and liquid specific impulse is reduced to some 390 to 470 seconds, a level about equal to the impulse of a high energy rocket engine. The envelope can be further extended, but only with increasing sacrifices in liquid specific impulse. Oxygen-airflow ratios as high as 15 percent were investigated for increasing thrust. Using 15 percent oxygen in combination with water injection at high supersonic Mach numbers resulted in thrust augmentation as high as 76 percent without any significant decrease in liquid specific impulse. The stoichiometric afterburner exit temperature increased with increasing oxygen flow, reaching 4822 deg R in the turbojet engine at a Mach number of 3.5. At the transonic Mach number of 0.95 where no water injection is needed, an oxygen-air ratio of 15 percent increased thrust by some 55 percent in both engines, along with a decrease in liquid specific impulse of 62 percent. Afterburner temperature was approximately 4700 deg R at this high thrust condition. Water and/or oxygen injection are simple and straightforward strategies to improve engine performance and they will add little to engine weight. However, if large Mach number and thrust increases are required, liquid flows become significant, so that operation at these conditions will necessarily be of short duration.
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Maximal exercise and muscle oxygen extraction in acclimatizing lowlanders and high altitude natives
DEFF Research Database (Denmark)
Lundby, Carsten; Sander, Mikael; van Hall, Gerrit
2006-01-01
, and is the focus of the present study. We have studied six lowlanders during maximal exercise at sea level (SL) and with acute (AH) exposure to 4,100 m altitude, and again after 2 (W2) and 8 weeks (W8) of altitude sojourn, where also eight high altitude native (Nat) Aymaras were studied. Fractional arterial muscle...... O(2) extraction at maximal exercise was 90.0+/-1.0% in the Danish lowlanders at sea level, and remained close to this value in all situations. In contrast to this, fractional arterial O(2) extraction was 83.2+/-2.8% in the high altitude natives, and did not change with the induction of normoxia....... The capillary oxygen conductance of the lower extremity, a measure of oxygen diffusing capacity, was decreased in the Danish lowlanders after 8 weeks of acclimatization, but was still higher than the value obtained from the high altitude natives. The values were (in ml min(-1) mmHg(-1)) 55.2+/-3.7 (SL), 48...
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Blood oxygenation level dependent (BOLD). Renal imaging. Concepts and applications
International Nuclear Information System (INIS)
Nissen, Johanna C.; Haneder, Stefan; Schoenberg, Stefan O.; Michaely, Henrik J.
2010-01-01
Many renal diseases as well as several pharmacons cause a change in renal blood flow and/or renal oxygenation. The blood oxygenation level dependent (BOLD) imaging takes advantage of local field inhomogeneities and is based on a T2 * -weighted sequence. BOLD is a non-invasive method allowing an estimation of the renal, particularly the medullary oxygenation, and an indirect measurement of blood flow without administration of contrast agents. Thus, effects of different drugs on the kidney and various renal diseases can be controlled and observed. This work will provide an overview of the studies carried out so far and identify ways how BOLD can be used in clinical studies. (orig.)
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The use of oxygen in hazardous waste incineration
International Nuclear Information System (INIS)
Ho, M.D.; Ding, M.G.
1989-01-01
The use of advanced oxygen combustion technologies in hazardous waste (such as PCBs and hydrocarbons) incineration has emerged in the last two years as one of the most significant breakthroughs among all the competing treatment technologies. For many years, industrial furnaces have used oxygen enrichment of the combustion air and oxygen-fuel burners, but with conventional technologies a high oxygen level generally poses problems. The flame temperature is high, leading to high NOx formation and local overeating. Different technical approaches to overcome these problems and their respective effectiveness will be reviewed. Previously, commercial oxygen enrichment in incinerators was limited to a rather modest level applications of much higher oxygen enrichment levels in hazardous waste incinerators
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Experimental studies on radiation effects under high pressure oxygen
Energy Technology Data Exchange (ETDEWEB)
Fujimura, E [Osaka Univ. (Japan). School of Dentistry
1974-06-01
The effect of oxygen tension on the radiosensitivity of tumor cells is well known, but its clinical application for radiotherapy is not yet established. Rabbits with V x 2 carcinoma in the maxilla were irradiated by /sup 60/Co under high pressure oxygen (experimental group), and compared with those treated in air (control group). For the purpose of examining the clinical effects of high pressure oxygen, an experiment was made in vivo. The following items were compared respectively: a) Tumor regression effect b) Tumor clearance rate c) Survival days d) Half size reduction time e) Inhibition of DNA synthesis in the tumor tissue. Results obtained were as follows: a) 56 per cent of animals showed tumor regression in the experimental group, whereas it occured 26 per cent in the control group. b) 53 per cent of animals showed tumor disappearance in the experimental group, while it was observed only in 13 per cent in the control group. c) Only 2 of 30 rabbits irradiated in air survived over 180 days, whereas 11 of 30 rabbits survived meanwhile in the group irradiated under high pressure oxygen. d) About 11 days were necessary to reduce the tumor size by half after irradiation in the group under high pressure oxygen, while it took 17 days in the group treated in normal air. e) DNA synthesis was inhibited more prominently in the group irradiated under high pressure oxygen in normal air.
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High oxygen as an additional factor in food preservation
Amanatidou, A.
2001-01-01
In this thesis, the efficacy of high oxygen as an additional hurdle for food preservation is studied. At high oxygen conditions and at low temperature, significant impairment of growth and viability of bacterial cells is found to occur as the result of free
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International Nuclear Information System (INIS)
Epp, E.R.; Ling, C.C.; Weiss, H.
1976-01-01
This paper discusses advances made on both experimental and theoretical approaches involving single and double pulses of high intensity ionizing radiation delivered to cultured bacterial and mammalian cells where the effect of oxygen is concerned. Information gained on the lifetime of oxygen-sensitive species suspected to be produced in critical molecules in irradiated cells and perhaps intimately related to the still unknown mechanisms of oxygen sensitization is described. The diffusion characteristics of oxygen at the cellular level obtained from experimental data are discussed. Current knowledge on intracellular radiolytic oxygen depletion is also presented. Future work on the use of high intensity pulsed radiation as a tool in cellular radiobiological research is outlined. It is expected that obtaining knowledge of the time available for damaged molecules to enter into chemical reactions may lead to insights into the mechanisms of radiation injury in cells, such as those involved in the oxygen effect. (Auth.)
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Shi, D; Li, X; Chen, H; Che, N; Zhou, S; Lu, Z; Shi, S; Sun, L
2014-12-01
Some lines of evidence have demonstrated abnormalities of bone marrow mesenchymal stem cells (MSCs) in systemic lupus erythematosus (SLE) patients, characterized by defective phenotype of MSCs and slower growth with enhanced apoptosis and senescence. However, whether SLE MSCs demonstrate aberrant migration capacity or abnormalities in cytoskeleton are issues that remain poorly understood. In this study, we found that MSCs from SLE patients did show impairment in migration capacity as well as abnormalities in F-actin cytoskeleton, accompanied by a high level of intracellular reactive oxygen species (ROS). When normal MSCs were treated in vitro with H2O2, which increases intracellular ROS level as an oxidant, both reorganization of F-actin cytoskeleton and impairment of migration capability were observed. On the other hand, treatment with N-acetylcysteine (NAC), as an exogenous antioxidant, made F-actin more orderly and increased migration ratio in SLE MSCs. In addition, oral administration of NAC markedly reduced serum autoantibody levels and ameliorated lupus nephritis (LN) in MRL/lpr mice, partially reversing the abnormalities of MSCs. These results indicate that overpolymerization of F-actin cytoskeleton, which may be associated with high levels of ROS, causes impairment in the migration capacity of SLE MSCs and that oral administration of NAC may have potential therapeutic effects on MRL/lpr mice. Copyright © 2014 Elsevier Masson SAS. All rights reserved.
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High Selectivity Oxygen Delignification
Energy Technology Data Exchange (ETDEWEB)
Lucian A. Lucia
2005-11-15
Project Objective: The objectives of this project are as follows: (1) Examine the physical and chemical characteristics of a partner mill pre- and post-oxygen delignified pulp and compare them to lab generated oxygen delignified pulps; (2) Apply the chemical selectivity enhancement system to the partner pre-oxygen delignified pulps under mill conditions (with and without any predetermined amounts of carryover) to determine how efficiently viscosity is preserved, how well selectivity is enhanced, if strength is improved, measure any yield differences and/or bleachability differences; and (3) Initiate a mill scale oxygen delignification run using the selectivity enhancement agent, collect the mill data, analyze it, and propose any future plans for implementation.
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High temperature properties of Zircaloy--oxygen alloys
International Nuclear Information System (INIS)
Mellinger, G.B.; Bates, J.L.
1977-03-01
The effect of oxygen on three properties of Zircaloy-4 cladding relevant to LOCA evaluation codes was determined. Thermal expansion, elastic moduli, and thermal diffusivity were measured over the range room temperature--1200 0 C (2192 0 F) and 0.7 to 28 at.% oxygen. Thermal expansion and elastic moduli showed increases with oxygen concentration, while thermal diffusivity tended to decrease. Zircaloy-2 was examined over the same temperature range, but only to 5 at.% oxygen, differences in the properties between the two alloys were minor. The thermal emittance of Zircaloy-4 was measured in argon over the wavelength range 1.5 to 2.5 μm on previously oxidized tubing and on surfaces in the process of oxidizing in unlimited steam. For the latter, a high emittance (approximately 0.9) was reached at an oxide thickness of about 100 mg/dm 2 , and the tubing surface remained black and substoichiometric as oxidation continued at temperatures to 1200 0 C
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Ren, Si-Hua; He, Yu-Xin; Ma, Yi-Ran; Jin, Jing-Chun; Kang, Dan
2016-02-01
To investigate the effects of oxygen concentration and reactive oxygen species (ROS) on the biological characteristics of hematopoietic stem cells (HSC) and to analyzed the relationship among the oxygen concentration, ROS and the biological characteristics of mouse HSC through simulation of oxygen environment experienced by PB HSC during transplantation. The detection of reactive oxygen species (ROS), in vitro amplification, directional differentiation (BFU-E, CFU-GM, CFU-Mix), homing of adhesion molecules (CXCR4, CD44, VLA4, VLA5, P-selectin), migration rate, CFU-S of NOD/SCID mice irradiated with sublethal dose were performed to study the effect of oxgen concentration and reactive oxygen species on the biological characteristics of mouse BM-HSC and the relationship among them. The oxygen concentrations lower than normal oxygen concentration (especially hypoxic oxygen environment) could reduce ROS level and amplify more Lin(-) c-kit(+) Sca-1(+) BM HSC, which was more helpful to the growth of various colonies (BFU-E, CFU-GM, CFU-Mix) and to maintain the migratory ability of HSC, thus promoting CFU-S growth significantly after the transplantation of HSC in NOD/SCID mice irradiated by a sublethal dose. BM HSC exposed to oxygen environments of normal, inconstant oxygen level and strenuously thanging of oxygen concentration could result in higher level of ROS, at the same time, the above-mentioned features and functional indicators were relatively lower. The ROS levels of BM HSC in PB HSCT are closely related to the concentrations and stability of oxygen surrounding the cells. High oxygen concentration results in an high level of ROS, which is not helpful to maintain the biological characteristics of BM HSC. Before transplantation and in vitro amplification, the application of antioxidancs and constant oxygen level environments may be beneficial for transplantation of BMMSC.
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Balance of oxygen throughout the conversion of a high-level waste melter feed to glass
Czech Academy of Sciences Publication Activity Database
Lee, S.M.; Hrma, P.; Kloužek, Jaroslav; Pokorný, R.; Hujová, Miroslava; Dixon, D.R.; Schweiger, M. J.; Kruger, A.A.
2017-01-01
Roč. 43, č. 16 (2017), s. 13113-13118 ISSN 0272-8842 Institutional support: RVO:67985891 Keywords : oxygen mass balance * feed-to-glass conversion * evolved gas * oxygen partial pressure * Fe redox ratio Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass OBOR OECD: Ceramics Impact factor: 2.986, year: 2016
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High-pressure oxygenation of thin-wall YBCO single-domain samples
International Nuclear Information System (INIS)
Chaud, X; Savchuk, Y; Sergienko, N; Prikhna, T; Diko, P
2008-01-01
The oxygen annealing of ReBCO bulk material, necessary to achieve superconducting properties, usually induces micro- and macro-cracks. This leads to a crack-assisted oxygenation process that allows oxygenating large bulk samples faster than single crystals. But excellent superconducting properties are cancelled by the poor mechanical ones. More progressive oxygenation strategy has been shown to reduce drastically the oxygenation cracks. The problem then arises to keep a reasonable annealing time. The concept of bulk Y123 single-domain samples with thin-wall geometry has been introduced to bypass the inherent limitation due to a slow oxygen diffusion rate. But it is not enough. The use of a high oxygen pressure (16 MPa) enables to speed up further the process. It introduces a displacement in the equilibrium phase diagram towards higher temperatures, i.e., higher diffusion rates, to achieve a given oxygen content in the material. Remarkable results were obtained by applying such a high pressure oxygen annealing process on thin-wall single-domain samples. The trapped field of 16 mm diameter Y123 thin-wall single-domain samples was doubled (0.6T vs 0.3T at 77K) using an annealing time twice shorter (about 3 days). The initial development was made on thin bars. The advantage of thin-wall geometry is that such an annealing can be applied directly to a much larger sample
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Badiger, S; John, M; Fearnley, R A; Ahmad, I
2015-10-01
Awake fibre-optic intubation is a widely practised technique for anticipated difficult airway management. Despite the administration of supplemental oxygen during the procedure, patients are still at risk of hypoxia because of the effects of sedation, local anaesthesia, procedural complications, and the presence of co-morbidities. Traditionally used oxygen-delivery devices are low flow, and most do not have a sufficient reservoir or allow adequate fresh gas flow to meet the patient's peak inspiratory flow rate, nor provide an adequate fractional inspired oxygen concentration to prevent desaturation should complications arise. A prospective observational study was conducted using a high-flow humidified transnasal oxygen-delivery system during awake fibre-optic intubation in 50 patients with anticipated difficult airways. There were no episodes of desaturation or hypercapnia using the high-flow system, and in all patients the oxygen saturation improved above baseline values, despite one instance of apnoea resulting from over-sedation. All patients reported a comfortable experience using the device. The high-flow nasal oxygen-delivery system improves oxygenation saturation, decreases the risk of desaturation during the procedure, and potentially, optimizes conditions for awake fibre-optic intubation. The soft nasal cannulae uniquely allow continuous oxygenation and simultaneous passage of the fibrescope and tracheal tube. The safety of the procedure may be increased, because any obstruction, hypoventilation, or periods of apnoea that may arise may be tolerated for longer, allowing more time to achieve ventilation in an optimally oxygenated patient. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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The effects of oxygen level and glucose concentration on the metabolism of porcine TMJ disc cells.
Cisewski, S E; Zhang, L; Kuo, J; Wright, G J; Wu, Y; Kern, M J; Yao, H
2015-10-01
To determine the combined effect of oxygen level and glucose concentration on cell viability, ATP production, and matrix synthesis of temporomandibular joint (TMJ) disc cells. TMJ disc cells were isolated from pigs aged 6-8 months and cultured in a monolayer. Cell cultures were preconditioned for 48 h with 0, 1.5, 5, or 25 mM glucose DMEM under 1%, 5%, 10%, or 21% O2 level, respectively. The cell viability was measured using the WST-1 assay. ATP production was determined using the Luciferin-Luciferase assay. Collagen and proteoglycan synthesis were determined by measuring the incorporation of [2, 3-(3)H] proline and [(35)S] sulfate into the cells, respectively. TMJ disc cell viability significantly decreased (P oxygen levels significantly increased viability (P oxygen levels significantly reduced ATP production (P oxygen was significant in regards to cell viability (P oxygen are important, glucose is the limiting nutrient for TMJ disc cell survival. At low oxygen levels, the production of ATP, collagen, and proteoglycan are severely inhibited. These results suggest that steeper nutrient gradients may exist in the TMJ disc and it may be vulnerable to pathological events that impede nutrient supply. Copyright © 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
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High-Pressure Oxygen Generation for Outpost EVA Study
Jeng, Frank F.; Conger, Bruce; Ewert, Michael K.; Anderson, Molly S.
2009-01-01
The amount of oxygen consumption for crew extravehicular activity (EVA) in future lunar exploration missions will be significant. Eight technologies to provide high pressure EVA O2 were investigated. They are: high pressure O2 storage, liquid oxygen (LOX) storage followed by vaporization, scavenging LOX from Lander followed by vaporization, LOX delivery followed by sorption compression, water electrolysis followed by compression, stand-alone high pressure water electrolyzer, Environmental Control and Life Support System (ECLSS) and Power Elements sharing a high pressure water electrolyzer, and ECLSS and In-Situ Resource Utilization (ISRU) Elements sharing a high pressure electrolyzer. A trade analysis was conducted comparing launch mass and equivalent system mass (ESM) of the eight technologies in open and closed ECLSS architectures. Technologies considered appropriate for the two architectures were selected and suggested for development.
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Heinonen, Ilkka; Kudomi, Nobuyuki; Kemppainen, Jukka; Kiviniemi, Antti; Noponen, Tommi; Luotolahti, Matti; Luoto, Pauliina; Oikonen, Vesa; Sipilä, Hannu T; Kopra, Jaakko; Mononen, Ilkka; Duncker, Dirk J; Knuuti, Juhani; Kalliokoski, Kari K
2014-07-01
Highly endurance-trained athlete's heart represents the most extreme form of cardiac adaptation to physical stress, but its circulatory alterations remain obscure. In the present study, myocardial blood flow (MBF), blood mean transit time (MTT), oxygen extraction fraction (OEF) and consumption (MVO2), and efficiency of cardiac work were quantified in highly trained male endurance athletes and control subjects at rest and during supine cycling exercise using [(15)O]-labeled radiotracers and positron emission tomography. Heart rate and MBF were lower in athletes both at rest and during exercise. OEF increased in response to exercise in both groups, but was higher in athletes (70 ± 21 vs. 63 ± 11 % at rest and 86 ± 13 vs. 73 ± 10 % during exercise). MTT was longer and vascular resistance higher in athletes both at rest and during exercise, but arterial content of 2,3-diphosphoglycerate (oxygen affinity) was unchanged. MVO2 per gram of myocardium trended (p = 0.08) lower in athletes both at rest and during exercise, while myocardial efficiency of work and MVO2 per beat were not different between groups. Arterial levels of free fatty acids were ~twofold higher in athletes likely leading to higher myocardial fatty acid oxidation and hence oxygen cost, which may have blunted the bradycardia-induced decrease in MVO2. Finally, the observed group differences in MBF, OEF, MTT and vascular resistance remained significant also after they were controlled for differences in MVO2. In conclusion, in highly endurance-trained human heart, increased myocardial blood transition time enables higher oxygen extraction levels with a lower myocardial blood flow and higher vascular resistance. These physiological adaptations to exercise training occur independently of the level of oxygen consumption and together with training-induced bradycardia may serve as mechanisms to increase functional reserve of the human heart.
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Reduced oxygen at high altitude limits maximum size.
Peck, L S; Chapelle, G
2003-11-07
The trend towards large size in marine animals with latitude, and the existence of giant marine species in polar regions have long been recognized, but remained enigmatic until a recent study showed it to be an effect of increased oxygen availability in sea water of a low temperature. The effect was apparent in data from 12 sites worldwide because of variations in water oxygen content controlled by differences in temperature and salinity. Another major physical factor affecting oxygen content in aquatic environments is reduced pressure at high altitude. Suitable data from high-altitude sites are very scarce. However, an exceptionally rich crustacean collection, which remains largely undescribed, was obtained by the British 1937 expedition from Lake Titicaca on the border between Peru and Bolivia in the Andes at an altitude of 3809 m. We show that in Lake Titicaca the maximum length of amphipods is 2-4 times smaller than other low-salinity sites (Caspian Sea and Lake Baikal).
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Limited oxygen index levels of impregnated Scots pine wood
International Nuclear Information System (INIS)
Tomak, Eylem Dizman; Cavdar, Ayfer Donmez
2013-01-01
Highlights: • Scots pine samples were treated with 4 wood preservatives with various concentrations. • Limited oxygen index level was evaluated both for leached and un-leached samples. • All treatments improved fire retardance of samples despite some chemicals leached out. • Samples treated with fireproof agent showed the best results. • LOI of samples treated with boron powder and silicon oil was not changed by leaching. - Abstract: In this study, effect of various concentrations of boron powder, mixture of boric acid and borax, fireproof agent based on liquid blend of limestone, and silicon oil on limited oxygen index levels (LOI) of S. pine wood was investigated. Wood samples were first vacuum treated with the preservatives, and then were subjected to leaching procedure. Samples treated with fireproof agent showed the best results for improving the fire retardancy of wood, furthermore, samples treated with 25%, 50% and 100% of the solution did not burn. Leaching did not considerably change the LOI of wood samples treated with boron powder and silicon oil; however, LOI levels of samples treated with the mixture of boric acid and borax and fireproof agent were affected by leaching procedure probably arising those preservatives did not chemically bond to main wood components. All treatments improved fire retardancy of samples despite some amount of preservatives leached out from wood
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Limited oxygen index levels of impregnated Scots pine wood
Energy Technology Data Exchange (ETDEWEB)
Tomak, Eylem Dizman, E-mail: eylemdizman@yahoo.com [Forest Industry Engineering Department, Faculty of Forestry, Bursa Technical University, 16200 Bursa (Turkey); Cavdar, Ayfer Donmez [Interior Architecture Department, Faculty of Architecture, Karadeniz Technical University, 61080 Trabzon (Turkey)
2013-12-10
Highlights: • Scots pine samples were treated with 4 wood preservatives with various concentrations. • Limited oxygen index level was evaluated both for leached and un-leached samples. • All treatments improved fire retardance of samples despite some chemicals leached out. • Samples treated with fireproof agent showed the best results. • LOI of samples treated with boron powder and silicon oil was not changed by leaching. - Abstract: In this study, effect of various concentrations of boron powder, mixture of boric acid and borax, fireproof agent based on liquid blend of limestone, and silicon oil on limited oxygen index levels (LOI) of S. pine wood was investigated. Wood samples were first vacuum treated with the preservatives, and then were subjected to leaching procedure. Samples treated with fireproof agent showed the best results for improving the fire retardancy of wood, furthermore, samples treated with 25%, 50% and 100% of the solution did not burn. Leaching did not considerably change the LOI of wood samples treated with boron powder and silicon oil; however, LOI levels of samples treated with the mixture of boric acid and borax and fireproof agent were affected by leaching procedure probably arising those preservatives did not chemically bond to main wood components. All treatments improved fire retardancy of samples despite some amount of preservatives leached out from wood.
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A high reliability oxygen deficiency monitoring system
International Nuclear Information System (INIS)
Parry, R.; Claborn, G.; Haas, A.; Landis, R.; Page, W.; Smith, J.
1993-05-01
The escalating use of cryogens at national laboratories in general and accelerators in particular, along with the increased emphasis placed on personnel safety, mandates the development and installation of oxygen monitoring systems to insure personnel safety in the event of a cryogenic leak. Numerous vendors offer oxygen deficiency monitoring systems but fail to provide important features and/or flexibility. This paper describes a unique oxygen monitoring system developed for the Magnet Test Laboratory (MTL) at the Superconducting Super Collider Laboratory (SSCL). Features include: high reliability, oxygen cell redundancy, sensor longevity, simple calibration, multiple trip points, offending sensor audio and visual indication, global alarms for building evacuation, local and remote analog readout, event and analog data logging, EMAIL event notification, phone line voice status system, and multi-drop communications network capability for reduced cable runs. Of particular importance is the distributed topology of the system which allows it to operate in a stand-alone configuration or to communicate with a host computer. This flexibility makes it ideal for small applications such as a small room containing a cryogenic dewar, as well as larger systems which monitor many offices and labs in several buildings
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A high reliability oxygen deficiency monitoring system
International Nuclear Information System (INIS)
Parry, R.; Claborn, G.; Haas, A.; Landis, R.; Page, W.; Smith, J.
1993-01-01
The escalating use of cryogens at national laboratories in general and accelerators in particular, along with the increased emphasis placed on personnel safety, mandates the development and installation of oxygen monitoring systems to insure personnel safety in the event of a cryogenic leak. Numerous vendors offer oxygen deficiency monitoring systems but fail to provide important features and/or flexibility. This paper describes a unique oxygen monitoring system developed for the Magnet Test Laboratory (MTL) at the Superconducting Super Collider Laboratory (SSCL). Features include: high reliability, oxygen cell redundancy, sensor longevity, simple calibration, multiple trip points, offending sensor audio and visual indication, global alarms for building evacuation, local and remote analog readout, event and analog data logging, EMAIL event notification, phone line voice status system, and multi-drop communications network capability for reduced cable runs. Of particular importance is the distributed topology of the system which allows it to operate in a stand-alone configuration or to communicate with a host computer. This flexibility makes it ideal for small applications such as a small room containing a cryogenic dewar, as well as larger systems which monitor many offices and labs in several buildings
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Stahl, J; Lindström, G; Pintilie, I
2003-01-01
Capacitance Deep Level Transient Spectroscopy (C-DLTS) measurements have been performed on standard and oxygen-doped silicon detectors manufactured from high-resistivity n-type float zone material with left angle bracket 111 right angle bracket and left angle bracket 100 right angle bracket orientation. Three different oxygen concentrations were achieved by the so-called diffusion oxygenated float zone (DOFZ) process initiated by the CERN-RD48 (ROSE) collaboration. Before the irradiation a material characterization has been performed. In contrast to radiation damage by neutrons or high- energy charged hadrons, were the bulk damage is dominated by a mixture of clusters and point defects, the bulk damage caused by **6**0Co-gamma-radiation is only due to the introduction of point defects. The dominant electrically active defects which have been detected after **6**0Co-gamma-irradiation by C-DLTS are the electron traps VO//i, C//iC//s, V//2( = /-), V //2(-/0) and the hole trap C//i O//i. The main difference betwe...
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Graf, John; Taylor, Dale; Martinez, James
2014-01-01
More than a metric ton of water is transported to the International Space Station (ISS) each year to provide breathing oxygen for the astronauts. Water is a safe and compact form of stored oxygen. The water is electrolyzed on ISS and ambient pressure oxygen is delivered to the cabin. A much smaller amount of oxygen is used each year in spacesuits to conduct Extra Vehicular Activities (EVAs). Space suits need high pressure (>1000 psia) high purity oxygen (must meet Aviator Breathing Oxygen "ABO" specifications, >99.5% O2). The water / water electrolysis system cannot directly provide high pressure, high purity oxygen, so oxygen for EVAs is transported to ISS in high pressure gas tanks. The tanks are relatively large and heavy, and the majority of the system launch weight is for the tanks and not the oxygen. Extracting high purity oxygen from cabin air and mechanically compressing the oxygen might enable on-board production of EVA grade oxygen using the existing water / water electrolysis system. This capability might also benefit human spaceflight missions, where oxygen for EVAs could be stored in the form of water, and converted into high pressure oxygen on-demand. Cerium oxide solid electrolyte-based ion transport membranes have been shown to separate oxygen from air, and a supported monolithic wafer form of the CeO2 electrolyte membrane has been shown to deliver oxygen at pressures greater than 300 psia. These supported monolithic wafers can withstand high pressure differentials even though the membrane is very thin, because the ion transport membrane is supported on both sides (Fig 1). The monolithic supported wafers have six distinct layers, each with matched coefficients of thermal expansion. The wafers are assembled into a cell stack which allows easy air flow across the wafers, uniform current distribution, and uniform current density (Fig 2). The oxygen separation is reported to be "infinitely selective" to oxygen [1] with reported purity of 99.99% [2
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Bimodular high temperature planar oxygen gas sensor
Directory of Open Access Journals (Sweden)
Xiangcheng eSun
2014-08-01
Full Text Available A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs thin film coated yttria-stabilized zirconia (YSZ substrate. The thin film was prepared by radio frequency (r.f. magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO nanoparticles film was characterized by atomic force microscopy (AFM and scanning electron microscopy (SEM. X-ray diffraction (XRD patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500 °C, 600 °C and 800 °C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors.
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Cross, Jane L; Boulos, Sherif; Shepherd, Kate L; Craig, Amanda J; Lee, Sharon; Bakker, Anthony J; Knuckey, Neville W; Meloni, Bruno P
2012-07-01
In this study we have assessed sodium-calcium exchanger (NCX) protein over-expression on cell viability in primary rat cortical neuronal and HEK293 cell cultures when subjected to oxygen-glucose deprivation (OGD). In cortical neuronal cultures, NCX2 and NCX3 over-expression was achieved using adenoviral vectors, and following OGD increased neuronal survival from ≈20% for control vector treated cultures to ≈80% for both NCX isoforms. In addition, we demonstrated that NCX2 and NCX3 over-expression in cortical neuronal cultures enables neurons to maintain intracellular calcium at significantly lower levels than control vector treated cultures when exposed to high (9mM) extracellular calcium challenge. Further assessment of NCX activity during OGD was performed using HEK293 cell lines generated to over-express NCX1, NCX2 or NCX3 isoforms. While it was shown that NCX isoform expression differed considerably in the different HEK293 cell lines, high levels of NCX over-expression was associated with increased resistance to OGD. Taken together, our findings show that high levels of NCX over-expression increases neuronal and HEK293 cell survival following OGD, improves calcium management in neuronal cultures and provides additional support for NCX as a therapeutic target to reduce ischemic brain injury. Copyright © 2012 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.
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Matharoo, Harpreet; Dabaghi, Mohammadhossein; Rochow, Niels; Fusch, Gerhard; Saraei, Neda; Tauhiduzzaman, Mohammed; Veldhuis, Stephen; Brash, John; Fusch, Christoph; Selvaganapathy, P Ravi
2018-01-01
Respiratory distress syndrome (RDS) is one of the main causes of fatality in newborn infants, particularly in neonates with low birth-weight. Commercial extracorporeal oxygenators have been used for low-birth-weight neonates in neonatal intensive care units. However, these oxygenators require high blood volumes to prime. In the last decade, microfluidics oxygenators using enriched oxygen have been developed for this purpose. Some of these oxygenators use thin polydimethylsiloxane (PDMS) membranes to facilitate gas exchange between the blood flowing in the microchannels and the ambient air outside. However, PDMS is elastic and the thin membranes exhibit significant deformation and delamination under pressure which alters the architecture of the devices causing poor oxygenation or device failure. Therefore, an alternate membrane with high stability, low deformation under pressure, and high gas exchange was desired. In this paper, we present a novel composite membrane consisting of an ultra-thin stainless-steel mesh embedded in PDMS, designed specifically for a microfluidic single oxygenator unit (SOU). In comparison to homogeneous PDMS membranes, this composite membrane demonstrated high stability, low deformation under pressure, and high gas exchange. In addition, a new design for oxygenator with sloping profile and tapered inlet configuration has been introduced to achieve the same gas exchange at lower pressure drops. SOUs were tested by bovine blood to evaluate gas exchange properties. Among all tested SOUs, the flat design SOU with composite membrane has the highest oxygen exchange of 40.32 ml/min m 2 . The superior performance of the new device with composite membrane was demonstrated by constructing a lung assist device (LAD) with a low priming volume of 10 ml. The LAD was achieved by the oxygen uptake of 0.48-0.90 ml/min and the CO 2 release of 1.05-2.27 ml/min at blood flow rates ranging between 8 and 48 ml/min. This LAD was shown to increase the
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High-power generator of singlet oxygen
Czech Academy of Sciences Publication Activity Database
Jirásek, Vít; Čenský, Miroslav; Špalek, Otomar; Kodymová, Jarmila
2013-01-01
Roč. 36, č. 10 (2013), s. 1755-1763 ISSN 0930-7516 Grant - others:Laser Science and Technology Centre(IN) LASTEC/FE/RKT/54/10-11 Institutional research plan: CEZ:AV0Z10100523 Keywords : high-pressure singlet oxygen generator * spray generator * centrifugal separation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.175, year: 2013
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The effects of high perioperative inspiratory oxygen fraction for adult surgical patients
DEFF Research Database (Denmark)
Wetterslev, Jørn; Meyhoff, Christian S; Jørgensen, Lars N
2015-01-01
BACKGROUND: Available evidence on the effects of a high fraction of inspired oxygen (FIO2) of 60% to 90% compared with a routine fraction of inspired oxygen of 30% to 40%, during anaesthesia and surgery, on mortality and surgical site infection has been inconclusive. Previous trials and meta......-analyses have led to different conclusions on whether a high fraction of supplemental inspired oxygen during anaesthesia may decrease or increase mortality and surgical site infections in surgical patients. OBJECTIVES: To assess the benefits and harms of an FIO2 equal to or greater than 60% compared...... and reran the searches in March 2015. We will consider two studies of interest when we update the review. SELECTION CRITERIA: We included randomized clinical trials that compared a high fraction of inspired oxygen with a routine fraction of inspired oxygen during anaesthesia, surgery and recovery...
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Spectroscopic Determination of Trace Contaminants in High Purity Oxygen
Hornung, Steven D.
2011-01-01
Oxygen used for extravehicular activities (EVA) must be free of contaminants because a difference in a few tenths of a percent of argon or nitrogen content can mean significant reduction in available EVA time. These inert gases build up in the extravehicular mobility unit because they are not metabolized or scrubbed from the atmosphere. Measurement of oxygen purity above 99.5% is problematic, and currently only complex instruments such as gas chromatographs or mass spectrometers are used for these determinations. Because liquid oxygen boil-off from the space shuttle will no longer be available to supply oxygen for EVA use, other concepts are being developed to produce and validate high purity oxygen from cabin air aboard the International Space Station. A prototype optical emission technique capable of detecting argon and nitrogen below 0.1% in oxygen was developed at White Sands Test Facility. This instrument uses a glow discharge in reduced pressure gas to produce atomic emission from the species present. Because the atomic emission lines from oxygen, nitrogen, and argon are discrete and in many cases well-separated, trace amounts of argon and nitrogen can be detected in the ultraviolet and visible spectrum. This is a straightforward, direct measurement of the target contaminants and may lend itself to a device capable of on-orbit verification of oxygen purity. System design and optimized measurement parameters are presented.
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Wu, Shichao; Qiao, Yu; Yang, Sixie; Ishida, Masayoshi; He, Ping; Zhou, Haoshen
2017-06-01
Reducing the high charge potential is a crucial concern in advancing the performance of lithium-oxygen batteries. Here, for water-containing lithium-oxygen batteries with lithium hydroxide products, we find that a hydrogen peroxide aqueous solution added in the electrolyte can effectively promote the decomposition of lithium hydroxide compounds at the ultralow charge potential on a catalyst-free Ketjen Black-based cathode. Furthermore, for non-aqueous lithium-oxygen batteries with lithium peroxide products, we introduce a urea hydrogen peroxide, chelating hydrogen peroxide without any water in the organic, as an electrolyte additive in lithium-oxygen batteries with a lithium metal anode and succeed in the realization of the low charge potential of ~3.26 V, which is among the best levels reported. In addition, the undesired water generally accompanying hydrogen peroxide solutions is circumvented to protect the lithium metal anode and ensure good battery cycling stability. Our results should provide illuminating insights into approaches to enhancing lithium-oxygen batteries.
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Guo, Chunxian; Zheng, Yao; Ran, Jingrun; Xie, Fangxi; Jaroniec, Mietek; Qiao, Shi-Zhang
2017-07-10
Engineering high-energy interfacial structures for high-performance electrocatalysis is achieved by chemical coupling of active CoO nanoclusters and high-index facet Mn 3 O 4 nano-octahedrons (hi-Mn 3 O 4 ). A thorough characterization, including synchrotron-based near edge X-ray absorption fine structure, reveals that strong interactions between both components promote the formation of high-energy interfacial Mn-O-Co species and high oxidation state CoO, from which electrons are drawn by Mn III -O present in hi-Mn 3 O 4 . The CoO/hi-Mn 3 O 4 demonstrates an excellent catalytic performance over the conventional metal oxide-based electrocatalysts, which is reflected by 1.2 times higher oxygen evolution reaction (OER) activity than that of Ru/C and a comparable oxygen reduction reaction (ORR) activity to that of Pt/C as well as a better stability than that of Ru/C (95 % vs. 81 % retained OER activity) and Pt/C (92 % vs. 78 % retained ORR activity after 10 h running) in alkaline electrolyte. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Improvement of lipase production at different stirring speeds and oxygen levels
Directory of Open Access Journals (Sweden)
F.O.M. Alonso
2005-03-01
Full Text Available Lipase production by a Brazilian wild strain of Yarrowia lipolytica at different stirring speeds and air flow rates was studied. The relationship among lipid consumption, cell growth and lipase production by this microorganism is presented. The most pronounced effect of oxygen on lipase production was determined by stirring speed. Maximum lipase activity was detected in the late stationary phase at 200 rpm and an air flow rate of 1-2 dm³/min (0.8-1.7 vvm when the lipid source had been fully consumed. Higher stirring speeds resulted in mechanical and/or oxidative stress, while lower stirring speeds seemed to limit oxygen levels. An increase in the availability of oxygen at higher air flow rates led to faster lipid uptake and anticipation of enzyme release into the culture medium. The highest lipase production was obtained at 200 rpm and 1 dm³/min (0.8 vvm.
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Effect of oxygen supplementation in a hatchery at high altitude and ...
African Journals Online (AJOL)
The objective of this study was to investigate the effect of oxygen supplementation on broiler eggs in a hatchery at high altitude on the growth performance and ascites syndrome of broilers reared at low altitude. The treatment groups were low altitude with no oxygen supplemented in the hatchery (LA-NOX); high altitude with ...
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Serum Reactive Oxygen Metabolite Levels Predict Severe Exacerbations of Asthma
Nakamoto, Keitaro; Watanabe, Masato; Sada, Mitsuru; Inui, Toshiya; Nakamura, Masuo; Honda, Kojiro; Wada, Hiroo; Mikami, Yu; Matsuzaki, Hirotaka; Horie, Masafumi; Noguchi, Satoshi; Yamauchi, Yasuhiro; Koyama, Hikari; Kogane, Toshiyuki; Kohyama, Tadashi; Takizawa, Hajime
2016-01-01
Background and Purpose Bronchial asthma (BA) is a chronic airway disease characterized by airway hyperresponsiveness and remodeling, which are intimately linked to chronic airway inflammation. Reactive oxygen species (ROS) such as hydrogen peroxide are generated by inflammatory cells that are involved in the pathogenesis of BA. However, the role of ROS in the management of BA patients is not yet clear. We attempted to determine the role of ROS as a biomarker in the clinical setting of BA. Subjects and Methods We enrolled patients with BA from 2013 through 2015 and studied the degrees of asthma control, anti-asthma treatment, pulmonary function test results, fractional exhaled nitric oxide (FeNO), serum reactive oxygen metabolite (ROM) levels, and serum levels of interleukin (IL)-6 and IL-8. Results We recruited 110 patients with BA. Serum ROM levels correlated with white blood cell (WBC) count (rs = 0.273, p = 0.004), neutrophil count (rs = 0.235, p = 0.014), CRP (rs = 0.403, p < 0.001), and IL-6 (rs = 0.339, p < 0.001). Serum ROM levels and IL-8 and CRP levels negatively correlated with %FEV1 (rs = -0.240, p = 0.012, rs = -0.362, p < 0.001, rs = -0.197, p = 0.039, respectively). Serum ROM levels were significantly higher in patients who experienced severe exacerbation within 3 months than in patients who did not (339 [302–381] vs. 376 [352–414] CARR U, p < 0.025). Receiver-operating characteristics analysis showed that ROM levels correlated significantly with the occurrence of severe exacerbation (area under the curve: 0.699, 95% CI: 0.597–0.801, p = 0.025). Conclusions Serum levels of ROM were significantly associated with the degrees of airway obstruction, WBC counts, neutrophil counts, IL-6, and severe exacerbations. This biomarker may be useful in predicting severe exacerbations of BA. PMID:27776186
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Vianen, GJ; Van den Thillart, GEEJM; Van Kampen, M; Van Heel, TI; Steffens, AB
By measuring the lactate response it is possible to determine whether a teleost is able to adapt to a certain oxygen level. It is hypothesized that recovery will occur at oxygen levels above the critical oxygen level (PO2)(crit) reflected by a transient lactate increase. In contrast, continuous
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High Temperature Oxidation of Steel in an Oxygen-enriched Low NOX Furnace Environment
Energy Technology Data Exchange (ETDEWEB)
Poirier, D.; Grandmaison, E.W. [Department of Chemical Engineering, Queen' s University, Kingston, ON K7L 3N6 (Canada); Matovic, M.D. [Department of Mechanical and Materials Engineering, Queen' s University, Kingston, ON K7L 3N6 (Canada); Barnes, K.R. [KB Technical Services, Inc (formerly) Stelco Inc, Research Manager, Stelco Inc., P.O. Box 2030, Hamilton, ON L8N 3T1 (Canada); Nelson, B.D. [Department of Chemical Engineering, Senior Researcher, Dofasco Inc., P.O. Box 2460, Hamilton, ON L8N 3J5 (Canada)
2006-09-15
Steel scaling tests have been performed in a research furnace utilizing an oxygen-enriched, low NOX, burner. This work was performed in conjunction with a study of the combustion characteristics for the Canadian Gas Research Institute (CGRI) low NOX burner. The furnace (a facility of the Centre for Advanced Gas Combustion Technology (CAGCT)) was fired with the burner mounted in a sidewall configuration similar to the geometry encountered in steel reheat furnaces. Scale habit, intactness, adhesion and oxidation rates were examined for five grades of steel over a range of stack oxygen concentrations ({approx}0.8% - {approx}4.3%) and oxygen enrichment levels (0-90%) at 1100C. Steel grade had the largest effect on scaling properties examined in this work. Within the tests for each grade, stack oxygen concentration had the largest effect on the scaling properties while oxygen enrichment level had only a small effect.
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International Nuclear Information System (INIS)
Schouborg, Jakob; Raarup, Merete K; Balling, Peter
2009-01-01
A high-resolution core-level spectroscopy investigation of the adsorption of oxygen on Al(111) at variable oxygen exposure demonstrates a low surface reactivity for an intensively cleaned surface. The threshold for oxide formation is as high as ∼200 L (langmuirs), at which point the coverage of the chemisorbed oxygen exceeds half a monolayer. A simple model is presented, using which it is possible to deduce the oxygen coverage from the core-level spectra and determine the initial sticking probability. For our data a value of 0.018 ± 0.004 is obtained. The changes in core-level spectra following low-temperature annealing of low-coverage O/Al(111) reflect the formation of gradually larger islands of oxygen atoms (Ostwald ripening). The island formation is consistent with a random-walk model from which the diffusion barrier can be deduced to be in the range of 0.80-0.90 eV.
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25(OHD3 Levels Relative to Muscle Strength and Maximum Oxygen Uptake in Athletes
Directory of Open Access Journals (Sweden)
Książek Anna
2016-04-01
Full Text Available Vitamin D is mainly known for its effects on the bone and calcium metabolism. The discovery of Vitamin D receptors in many extraskeletal cells suggests that it may also play a significant role in other organs and systems. The aim of our study was to assess the relationship between 25(OHD3 levels, lower limb isokinetic strength and maximum oxygen uptake in well-trained professional football players. We enrolled 43 Polish premier league soccer players. The mean age was 22.7±5.3 years. Our study showed decreased serum 25(OHD3 levels in 74.4% of the professional players. The results also demonstrated a lack of statistically significant correlation between 25(OHD3 levels and lower limb muscle strength with the exception of peak torque of the left knee extensors at an angular velocity of 150°/s (r=0.41. No significant correlations were found between hand grip strength and maximum oxygen uptake. Based on our study we concluded that in well-trained professional soccer players, there was no correlation between serum levels of 25(OHD3 and muscle strength or maximum oxygen uptake.
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Energy Technology Data Exchange (ETDEWEB)
Sedlacik, Jan [St. Jude Children' s Research Hospital, Memphis, TN (United States). Div. of Translational Imaging Research; University Clinics Jena (Germany). Medical Physics Group; Rauscher, Alexander [University Clinics Jena (Germany). Medical Physics Group; British Columbia Univ., Vancouver (Canada). MRI Research Centre; Reichenbach, Juergen R. [University Clinics Jena (Germany). Medical Physics Group
2009-07-01
The transverse magnetization of a single vein and its surrounding tissue is subject to spin dephasing caused by the local magnetic field inhomogeneity which is induced by the very same vessel. This phenomenon can be approximated and simulated by applying the model of an infinitely long and homogeneously magnetized cylinder embedded in a homogeneous tissue background. It is then possible to estimate the oxygenation level of the venous blood by fitting the simulated magnetization-time-course to the measured signal decay. In this work we demonstrate the ability of this approach to quantify the blood oxygenation level (Y) of small cerebral veins in vivo, not only under normal physiologic conditions (Y{sub native}=0.5-0.55) but also during induced changes of physiologic conditions which affect the cerebral venous blood oxygenation level. Changes of blood's oxygenation level induced by carbogen (5% CO{sub 2}, 95% O{sub 2}) and caffeine were observed and quantified, resulting in values of Y{sub carbogen}=0.7 and Y{sub caffeine}=0.42, respectively. The proposed technique may ultimately help to better understand local changes in cerebral physiology during neuronal activation by quantifying blood oxygenation in veins draining active brain areas. It may also be beneficial in clinical applications where it may improve diagnosis of cerebral pathologies as well as monitoring of responses to therapy. (orig.)
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High performance platinum single atom electrocatalyst for oxygen reduction reaction
Liu, Jing; Jiao, Menggai; Lu, Lanlu; Barkholtz, Heather M.; Li, Yuping; Wang, Ying; Jiang, Luhua; Wu, Zhijian; Liu, Di-Jia; Zhuang, Lin; Ma, Chao; Zeng, Jie; Zhang, Bingsen; Su, Dangsheng; Song, Ping; Xing, Wei; Xu, Weilin; Wang, Ying; Jiang, Zheng; Sun, Gongquan
2017-07-01
For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm-2 at 80 °C with a low platinum loading of 0.09 mgPt cm-2, corresponding to a platinum utilization of 0.13 gPt kW-1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.
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Clinical studies with high flow nasal cannula oxygen delivery in 2015
Directory of Open Access Journals (Sweden)
David Sotello
2016-04-01
Full Text Available HFNC devices can provide humidified oxygen at high flow rates with high FiO2s. This method of oxygen delivery appears to be more comfortable than using noninvasive ventilation, and it does improve oxygenation, reduce respiratory rates, and reduce the sense of dyspnea. This modality has been studied most in patients with acute hypoxemic respiratory failure. The study reported by Frat et al provides good evidence that patients with moderate to severe respiratory failure (PaO2/FiO2 < 200 may benefit the most. The more complex the patient’s underlying medical problems are the more likely HFNC therapy to fail
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Orlova, A. G.; Kirillin, M. Yu.; Volovetsky, A. B.; Shilyagina, N. Yu.; Sergeeva, E. A.; Golubiatnikov, G. Yu.; Turchin, I. V.
2017-07-01
Using diffuse optical spectroscopy the level of oxygenation and hemoglobin concentration in experimental tumor in comparison with normal muscle tissue of mice have been studied. Subcutaneously growing SKBR-3 was used as a tumor model. Continuous wave fiber probe diffuse optical spectroscopy system was employed. Optical properties extraction approach was based on diffusion approximation. Decreased blood oxygen saturation level and increased total hemoglobin content were demonstrated in the neoplasm. The main reason of such differences between tumor and norm was significant elevation of deoxyhemoglobin concentration in SKBR-3. The method can be useful for diagnosis of tumors as well as for study of blood flow parameters of tumor models with different angiogenic properties.
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HIGH PERFORMANCE CERIA BASED OXYGEN MEMBRANE
DEFF Research Database (Denmark)
2014-01-01
The invention describes a new class of highly stable mixed conducting materials based on acceptor doped cerium oxide (CeO2-8 ) in which the limiting electronic conductivity is significantly enhanced by co-doping with a second element or co- dopant, such as Nb, W and Zn, so that cerium and the co......-dopant have an ionic size ratio between 0.5 and 1. These materials can thereby improve the performance and extend the range of operating conditions of oxygen permeation membranes (OPM) for different high temperature membrane reactor applications. The invention also relates to the manufacturing of supported...
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Lee, Seung Yeob; Yang, Sung
2018-04-25
Most conventional hypoxic cell culture systems undergo reoxygenation during experimental manipulations, resulting in undesirable effects including the reduction of cell viability. A lid device was developed herein for conventional cell culture dishes to resolve this limitation. The integration of multilayered microfluidic channels inside a thin membrane was designed to prevent the reoxygenation caused by reagent infusion and automatically control the oxygen level. The experimental data clearly show the reducibility of the dissolved oxygen in the infusing reagent and the controllability of the oxygen level inside the dish. The feasibility of the device for hypoxia studies was confirmed by HIF-1α experiments. Therefore, the device could be used as a compact and convenient hypoxic cell culture system to prevent reoxygenation-related issues.
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Lajoie, Isabelle; Tancredi, Felipe B; Hoge, Richard D
2017-01-01
Recent calibrated fMRI techniques using combined hypercapnia and hyperoxia allow the mapping of resting cerebral metabolic rate of oxygen (CMRO2) in absolute units, oxygen extraction fraction (OEF) and calibration parameter M (maximum BOLD). The adoption of such technique necessitates knowledge about the precision and accuracy of the model-derived parameters. One of the factors that may impact the precision and accuracy is the level of oxygen provided during periods of hyperoxia (HO). A high level of oxygen may bring the BOLD responses closer to the maximum M value, and hence reduce the error associated with the M interpolation. However, an increased concentration of paramagnetic oxygen in the inhaled air may result in a larger susceptibility area around the frontal sinuses and nasal cavity. Additionally, a higher O2 level may generate a larger arterial blood T1 shortening, which require a bigger cerebral blood flow (CBF) T1 correction. To evaluate the impact of inspired oxygen levels on M, OEF and CMRO2 estimates, a cohort of six healthy adults underwent two different protocols: one where 60% of O2 was administered during HO (low HO or LHO) and one where 100% O2 was administered (high HO or HHO). The QUantitative O2 (QUO2) MRI approach was employed, where CBF and R2* are simultaneously acquired during periods of hypercapnia (HC) and hyperoxia, using a clinical 3 T scanner. Scan sessions were repeated to assess repeatability of results at the different O2 levels. Our T1 values during periods of hyperoxia were estimated based on an empirical ex-vivo relationship between T1 and the arterial partial pressure of O2. As expected, our T1 estimates revealed a larger T1 shortening in arterial blood when administering 100% O2 relative to 60% O2 (T1LHO = 1.56±0.01 sec vs. T1HHO = 1.47±0.01 sec, P < 4*10-13). In regard to the susceptibility artifacts, the patterns and number of affected voxels were comparable irrespective of the O2 concentration. Finally, the model
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Directory of Open Access Journals (Sweden)
Isabelle Lajoie
Full Text Available Recent calibrated fMRI techniques using combined hypercapnia and hyperoxia allow the mapping of resting cerebral metabolic rate of oxygen (CMRO2 in absolute units, oxygen extraction fraction (OEF and calibration parameter M (maximum BOLD. The adoption of such technique necessitates knowledge about the precision and accuracy of the model-derived parameters. One of the factors that may impact the precision and accuracy is the level of oxygen provided during periods of hyperoxia (HO. A high level of oxygen may bring the BOLD responses closer to the maximum M value, and hence reduce the error associated with the M interpolation. However, an increased concentration of paramagnetic oxygen in the inhaled air may result in a larger susceptibility area around the frontal sinuses and nasal cavity. Additionally, a higher O2 level may generate a larger arterial blood T1 shortening, which require a bigger cerebral blood flow (CBF T1 correction. To evaluate the impact of inspired oxygen levels on M, OEF and CMRO2 estimates, a cohort of six healthy adults underwent two different protocols: one where 60% of O2 was administered during HO (low HO or LHO and one where 100% O2 was administered (high HO or HHO. The QUantitative O2 (QUO2 MRI approach was employed, where CBF and R2* are simultaneously acquired during periods of hypercapnia (HC and hyperoxia, using a clinical 3 T scanner. Scan sessions were repeated to assess repeatability of results at the different O2 levels. Our T1 values during periods of hyperoxia were estimated based on an empirical ex-vivo relationship between T1 and the arterial partial pressure of O2. As expected, our T1 estimates revealed a larger T1 shortening in arterial blood when administering 100% O2 relative to 60% O2 (T1LHO = 1.56±0.01 sec vs. T1HHO = 1.47±0.01 sec, P < 4*10-13. In regard to the susceptibility artifacts, the patterns and number of affected voxels were comparable irrespective of the O2 concentration. Finally, the
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García-Lomillo, Javier; Viegas, Olga; Gonzalez-SanJose, Maria L; Ferreira, Isabel M P L V O
2017-03-01
Polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatic amines (HAs) are carcinogenic compounds formed in barbecued meat. Conditions that reduce their formation are of major interest. This study aims to evaluate the influence of red wine pomace seasoning (RWPS) and high-oxygen atmosphere storage on the formation of PAHs and HAs in barbecued beef patties. In general, the levels of PAHs and HAs quantified were low. The storage (9days) promoted higher formation of PAHs in control patties without increase of HAs. RWPS patties cooked at preparation day presented higher levels of PAHs and HAs than control. Nevertheless, RWPS patties cooked after storage presented lower levels of PAHs and HAs than control. ABTS assay pointed out that higher radical scavenging activity may be related to with lower PAHs or HAs formation. In conclusion, RWPS can be an interesting ingredient to inhibit the formation of cooking carcinogens in barbecued patties stored at high-oxygen atmosphere. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Directory of Open Access Journals (Sweden)
Chun Guo
2015-12-01
Full Text Available The low atmospheric pressure and low oxygen content in high-altitude environment have great impacts on the functions of human body. Especially for the personnel engaged in complicated physical labor such as tunnel construction, high altitude can cause a series of adverse physiological reactions, which may result in multiple high-altitude diseases and even death in severe cases. Artificial oxygen supply is required to ensure health and safety of construction personnel in hypoxic environments. However, there are no provisions for oxygen supply standard for tunnel construction personnel in high-altitude areas in current tunnel construction specifications. As a result, this paper has theoretically studied the impacts of high-altitude environment on human bodies, analyzed the relationship between labor intensity and oxygen consumption in high-altitude areas and determined the critical oxygen-supply altitude values for tunnel construction based on two different standard evaluation systems, i.e., variation of air density and equivalent PIO2. In addition, it has finally determined the oxygen supply standard for construction personnel in high-altitude areas based on the relationship between construction labor intensity and oxygen consumption.
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Directory of Open Access Journals (Sweden)
Hao-Jiang Yang
2013-07-01
Full Text Available AIM: To evaluate the outcome of high oxygen permeable contact lens used after photorefractive keratectomy(PRKsurgery.METHODS: Totally 95 patients(190 eyesafter PRK were included. Patients were randomly assigned to wear high oxygen permeable contact lens in one eye and normal lens in the fellow eye after surgery. The subjective symptoms and corneal epithelial status after PRK were evaluated. Uncorrected visual acuity(UCVAand haze were assessed at 6 months after PRK.RESULTS: Complaints of blurred vision, pain and photophobia were statistically more among the normal lens group than high oxygen permeable contact lens group(PPP=0.35. There was no difference in UCVA and haze 6 months after surgery(P=0.55. CONCLUSION: High oxygen permeable contact lens can significantly produce less the corneal irritated symptoms, reduce the discomfort feeling and promote healing of corneal epithelium after PRK.
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Structure of Greyhound hemoglobin: origin of high oxygen affinity.
Bhatt, Veer S; Zaldívar-López, Sara; Harris, David R; Couto, C Guillermo; Wang, Peng G; Palmer, Andre F
2011-05-01
This study presents the crystal structure of Greyhound hemoglobin (GrHb) determined to 1.9 Å resolution. GrHb was found to crystallize with an α₁β₁ dimer in the asymmetric unit and belongs to the R2 state. Oxygen-affinity measurements combined with the fact that GrHb crystallizes in the R2 state despite the high-salt conditions used for crystallization strongly indicate that GrHb can serve as a model high-oxygen-affinity hemoglobin (Hb) for higher mammals, especially humans. Structural analysis of GrHb and its comparison with the R2-state of human Hb revealed several regions that can potentially contribute to the high oxygen affinity of GrHb and serve to rationalize the additional stability of the R2-state of GrHb. A previously well studied hydrophobic cluster of bar-headed goose Hb near α119 was also incorporated in the comparison between GrHb and human Hb. Finally, a structural comparison with generic dog Hb and maned wolf Hb was conducted, revealing that in contrast to GrHb these structures belong to the R state of Hb and raising the intriguing possibility of an additional allosteric factor co-purifying with GrHb that can modulate its quaternary structure.
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Daines, Stuart J.; Mills, Benjamin J. W.; Lenton, Timothy M.
2017-02-01
It is unclear why atmospheric oxygen remained trapped at low levels for more than 1.5 billion years following the Paleoproterozoic Great Oxidation Event. Here, we use models for erosion, weathering and biogeochemical cycling to show that this can be explained by the tectonic recycling of previously accumulated sedimentary organic carbon, combined with the oxygen sensitivity of oxidative weathering. Our results indicate a strong negative feedback regime when atmospheric oxygen concentration is of order pO2~0.1 PAL (present atmospheric level), but that stability is lost at pO2counterbalancing changes in the weathering of isotopically light organic carbon. This can explain the lack of secular trend in the Precambrian δ13C record, and reopens the possibility that increased biological productivity and resultant organic carbon burial drove the Great Oxidation Event.
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Directory of Open Access Journals (Sweden)
Fen Chen
2018-03-01
Full Text Available Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI has recently been utilized as a noninvasive tool for evaluating renal oxygenation. Several methods have been proposed for analyzing BOLD images. Regional ROI selection is the earliest and most widely used method for BOLD analysis. In the last 20 years, many investigators have used this method to evaluate cortical and medullary oxygenation in patients with ischemic nephropathy, hypertensive nephropathy, diabetic nephropathy, chronic kidney disease (CKD, acute kidney injury and renal allograft rejection. However, clinical trials of BOLD MRI using regional ROI selection revealed that it was difficult to distinguish the renal cortico-medullary zones with this method, and that it was susceptible to observer variability. To overcome these deficiencies, several new methods were proposed for analyzing BOLD images, including the compartmental approach, fractional hypoxia method, concentric objects (CO method and twelve-layer concentric objects (TLCO method. The compartmental approach provides an algorithm to judge whether the pixel belongs to the cortex or medulla. Fractional kidney hypoxia, measured by using BOLD MRI, was negatively correlated with renal blood flow, tissue perfusion and glomerular filtration rate (GFR in patients with atherosclerotic renal artery stenosis. The CO method divides the renal parenchyma into six or twelve layers of thickness in each coronal slice of BOLD images and provides a R2* radial profile curve. The slope of the R2* curve associated positively with eGFR in CKD patients. Indeed, each method invariably has advantages and disadvantages, and there is generally no consensus method so far. Undoubtedly, analytic approaches for BOLD MRI with better reproducibility would assist clinicians in monitoring the degree of kidney hypoxia and thus facilitating timely reversal of tissue hypoxia.
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High Performance Electrocatalytic Reaction of Hydrogen and Oxygen on Ruthenium Nanoclusters
Energy Technology Data Exchange (ETDEWEB)
Ye, Ruquan; Liu, Yuanyue; Peng, Zhiwei; Wang, Tuo; Jalilov, Almaz S.; Yakobson, Boris I.; Wei, Su-Huai; Tour, James M.
2017-01-18
The development of catalytic materials for the hydrogen oxidation, hydrogen evolution, oxygen reduction or oxygen evolution reactions with high reaction rates and low overpotentials are key goals for the development of renewable energy. We report here Ru(0) nanoclusters supported on nitrogen-doped graphene as high-performance multifunctional catalysts for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR), showing activities similar to that of commercial Pt/C in alkaline solution. For HER performance in alkaline media, sample Ru/NG-750 reaches 10 mA cm-2 at an overpotential of 8 mV with a Tafel slope of 30 mV dec-1. The high HER performance in alkaline solution is advantageous because most catalysts for ORR and oxygen evolution reaction (OER) also prefer alkaline solution environment whereas degrade in acidic electrolytes. For ORR performance, Ru/NG effectively catalyzes the conversion of O2 into OH- via a 4e process at a current density comparable to that of Pt/C. The unusual catalytic activities of Ru(0) nanoclusters reported here are important discoveries for the advancement of renewable energy conversion reactions.
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High Pressure Electrochemical Oxygen Generation for ISS, Phase II
National Aeronautics and Space Administration — Giner, Inc. has developed an advanced high pressure electrochemical oxygen concentrator (EOC) that offers a simple alternative to the use of pressure swing...
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Breakdown of highly excited oxygen in a DC electric field
International Nuclear Information System (INIS)
Vagin, N.P.; Ionin, A.A.; Klimachev, Yu.M.; Sinitsin, D.V.; Yuryshev, N.N.; Deryugin, A.A.; Kochetov, I.V.; Napartovich, A.P.
2000-01-01
The breakdown of oxygen in a dc electric field is studied. A high concentration of oxygen molecules in the a 1 Δ g excited state is obtained in a purely chemical reactor. A decrease in the breakdown voltage at degrees of excitation exceeding 50% is observed. The theoretical decrement in the breakdown voltage obtained by solving the Boltzmann equation is in good agreement with the experimental data
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High or low oxygen saturation and severe retinopathy of prematurity: a meta-analysis.
Chen, Minghua L; Guo, Lei; Smith, Lois E H; Dammann, Christiane E L; Dammann, Olaf
2010-06-01
Low oxygen saturation appears to decrease the risk of severe retinopathy of prematurity (ROP) in preterm newborns when administered during the first few weeks after birth. High oxygen saturation seems to reduce the risk at later postmenstrual ages (PMAs). However, previous clinical studies are not conclusive individually. To perform a systematic review and meta-analysis to report the association between severe ROP incidence of premature infants with high or low target oxygen saturation measured by pulse oximetry. Studies were identified through PubMed and Embase literature searches through May 2009 by using the terms "retinopathy of prematurity and oxygen" or "retinopathy of prematurity and oxygen therapy." We selected 10 publications addressing the association between severe ROP and target oxygen saturation measured by pulse oximetry. Using a random-effects model we calculated the summary-effect estimate. We visually inspected funnel plots to examine possible publication bias. Low oxygen saturation (70%-96%) in the first several postnatal weeks was associated with a reduced risk of severe ROP (risk ratio [RR]: 0.48 [95% confidence interval (CI): 0.31-0.75]). High oxygen saturation (94%-99%) at > or = 32 weeks' PMA was associated with a decreased risk for progression to severe ROP (RR: 0.54 [95% CI: 0.35-0.82]). Among preterm infants with a gestational age of large randomized clinical trial with long-term developmental follow-up is warranted to confirm this meta-analytic result.
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A Cabin Air Separator for EVA Oxygen
Graf, John C.
2011-01-01
Presently, the Extra-Vehicular Activities (EVAs) conducted from the Quest Joint Airlock on the International Space Station use high pressure, high purity oxygen that is delivered to the Space Station by the Space Shuttle. When the Space Shuttle retires, a new method of delivering high pressure, high purity oxygen to the High Pressure Gas Tanks (HPGTs) is needed. One method is to use a cabin air separator to sweep oxygen from the cabin air, generate a low pressure/high purity oxygen stream, and compress the oxygen with a multistage mechanical compressor. A main advantage to this type of system is that the existing low pressure oxygen supply infrastructure can be used as the source of cabin oxygen. ISS has two water electrolysis systems that deliver low pressure oxygen to the cabin, as well as chlorate candles and compressed gas tanks on cargo vehicles. Each of these systems can feed low pressure oxygen into the cabin, and any low pressure oxygen source can be used as an on-board source of oxygen. Three different oxygen separator systems were evaluated, and a two stage Pressure Swing Adsorption system was selected for reasons of technical maturity. Two different compressor designs were subjected to long term testing, and the compressor with better life performance and more favorable oxygen safety characteristics was selected. These technologies have been used as the basis of a design for a flight system located in Equipment Lock, and taken to Preliminary Design Review level of maturity. This paper describes the Cabin Air Separator for EVA Oxygen (CASEO) concept, describes the separator and compressor technology trades, highlights key technology risks, and describes the flight hardware concept as presented at Preliminary Design Review (PDR)
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Autoionizing states in highly ionized oxygen, fluorine and silicon
International Nuclear Information System (INIS)
Forester, J.P.; Peterson, R.S.; Griffin, P.M.; Pegg, D.J.; Haselton, H.H.; Liao, K.H.; Sellin, I.A.; Mowat, J.R.; Thoe, R.S.
1975-01-01
Autoionizing states in high Z 3-electron ions associated with core excited configurations of the type 1s2snl and 1s2pnl are reported. The electron decay-in-flight spectra of lithium-like oxygen, fluorine, and silicon ions are presented. Initial beam energies of 6.75-MeV oxygen and fluorine ions and 22.5-MeV silicon ions were used. Stripping and excitation were done by passing the beams through a thin carbon foil. The experimental technique is described. 4 figs, 1 table, 7 refs
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... breathe increased amounts of oxygen to get normal levels of oxygen in their blood. Oxygen therapy provides babies with the extra oxygen. Information Oxygen is a gas that the cells in your body need to work properly. The ...
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Pérez, A G; Sanz, C
2001-05-01
The effect of high-oxygen atmospheres on strawberry flavor was studied. Strawberry fruits (Fragariax ananassa Duch. cv. Camarosa) were stored at 8 degrees C in four different atmospheres: air, 5% O(2)/20% CO(2), 80% O(2)/20% CO(2), and 90% O(2)/10% CO(2). Changes in several quality parameters were evaluated. Atmospheres combining high O(2) and high CO(2) were the most effective in preventing fungal growth and enhancing strawberry firmness. Other quality parameters such as color, titrable acidity, sugars and organic acids distribution, off-flavor development, and aroma were only mildly affected by superatmospheric O(2) levels. After one week of storage, unexpected high contents of off-flavor related compounds were found in the 80% O(2)/20% CO(2) and 90% O(2)/10% CO(2) atmospheres. Evidence of an altered ester biosynthesis was also found in fruits stored under these high-O(2) atmospheres. Data obtained suggest that stress induced by high CO(2) and stress induced by high O(2) have an additive effect on strawberry flavor alteration.
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International Nuclear Information System (INIS)
Fukuoka, Noboru; Kambe, Yoshiyuki; Saito, Haruo; Matsuda, Koji.
1984-05-01
Deep level transient spectroscopy was applied to the electron trapping levels which are associated with the irradiation induced lattice defects in germanium crystals. The germanium crystals used in the study were doped with oxygen, antimony or arsenic and the defects were formed by electron irradiation of 1.5MeV or 10MeV. The nature of so called ''thermal defect'' formed by heat treatment at about 670K was also studied. The trapping levels at Esub(c)-0.13eV, Esub(c)-0.25eV and Esub(c)-0.29eV were found to be associated with defects containing oxygen atoms. From the experimental results the Esub(c)-0.25eV level was attributed to the germanium A-center (interstitial oxygen atom-vacancy pair). Another defect associated with the 715cm -1 infrared absorption band was found to have a trapping level at the same position at Esub(c)-0.25eV. The Esub(c)-0.23eV and Esub(c)-0.1eV levels were revealed to be associated with thermal donors formed by heat treatment at about 670K. Additional two peaks (levels) were observed in the DLTS spectrum. The annealing behavior of the levels suggests that the thermal donors originate from not a single type but several types of defects. (author)
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Directory of Open Access Journals (Sweden)
Persi Bruno
2010-10-01
Full Text Available Abstract Introduction High frequency percussive ventilation is a ventilatory technique that delivers small bursts of high flow respiratory gas into the lungs at high rates. It is classified as a pneumatically powered, pressure-regulated, time-cycled, high-frequency flow interrupter modality of ventilation. High frequency percussive ventilation improves the arterial partial pressure of oxygen with the same positive end expiratory pressure and fractional inspiratory oxygen level as conventional ventilation using a minor mean airway pressure in an open circuit. It reduces the barotraumatic events in a hypoxic patient who has low lung-compliance. To the best of our knowledge, there have been no papers published about this ventilation modality in patients with severe hypoxaemia after cardiac surgery. Case presentation A 75-year-old Caucasian man with an ejection fraction of 27 percent, developed a lung infection with severe hypoxaemia [partial pressure of oxygen/fractional inspiratory oxygen of 90] ten days after cardiac surgery. Conventional ventilation did not improve the gas exchange. He was treated with high frequency percussive ventilation for 12 hours with a low conventional respiratory rate (five per minute. His cardiac output and systemic and pulmonary pressures were monitored. Compared to conventional ventilation, high frequency percussive ventilation gives an improvement of the partial pressure of oxygen from 90 to 190 mmHg with the same fractional inspiratory oxygen and positive end expiratory pressure level. His right ventricular stroke work index was lowered from 19 to seven g-m/m2/beat; his pulmonary vascular resistance index from 267 to 190 dynes•seconds/cm5/m2; left ventricular stroke work index from 28 to 16 gm-m/m2/beat; and his pulmonary arterial wedge pressure was lowered from 32 to 24 mmHg with a lower mean airway pressure compared to conventional ventilation. His cardiac index (2.7 L/min/m2 and ejection fraction (27 percent
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International Nuclear Information System (INIS)
Nishi, Toshio; Kanai, Kaname; Ouchi, Yukio; Willis, Martin R.; Seki, Kazuhiko
2006-01-01
The effect of oxygen doping on titanyl phthalocyanine (TiOPc) film was investigated by ultraviolet photoelectron spectroscopy (UPS). The electronic structure of the interface formed between TiOPc films deposited on highly oriented pyrolytic graphite (HOPG) was clearly different between the films prepared in ultrahigh vacuum (UHV) and under O 2 atmosphere (1.3 x 10 -2 Pa). The film deposited in UHV showed downward band bending characteristic of n-type semiconductor, possibly due to residual impurities working as unintentional n-type dopants. On the other hand, the film deposited under O 2 atmosphere showed upward band bending characteristic of p-type semiconductor. Such trends, including the conversion from n- to p-type, are in excellent correspondence with reported field effect transistor characteristics of TiOPc, and clearly demonstrates that bulk TiOPc film was p-doped with oxygen. In order to examine the Fermi level alignment between TiOPc film and the substrate, the energy of the highest occupied molecular orbital (HOMO) of TiOPc relative to the Fermi level of the conductive substrate was determined for various substrates. The alignment between the Fermi level of conductive substrate and Fermi level of TiOPc film at fixed energy in the bandgap was not observed for the TiOPc film prepared in UHV, possibly because of insufficient charge density in the TiOPc film. This situation was drastically changed when the TiOPc film exposed to O 2 , and clear alignment of the Fermi level fixed at 0.6 eV above the HOMO with the Fermi level of the conducting substrate was observed, probably by p-type doping effect of oxygen. These are the first direct and quantitative information about bulk oxygen doping from the viewpoint of the electronic structure. These results suggest that similar band bending with Fermi level alignment may be also achieved for other organic semiconductors under practical device conditions, and also call for caution at the comparison of experimental
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Composite Sr- and V-doped LaCrO3/YSZ sensor electrode operating at low oxygen levels
DEFF Research Database (Denmark)
Lund, Anders; Jacobsen, Torben; Hansen, Karin Vels
2012-01-01
A porous composite electrode of La0.8Sr0.2Cr0.97V0.03O3 -delta (LSCV) and yttria-stabilised zirconia (YSZ) was evaluated as a possible candidate for high-temperature potentiometric oxygen sensor measuring electrodes. The oxygen processes at the electrode were characterised by performing electroch....... The relatively low response time at 700º C at an oxygen partial pressure of around 5x10-6 bar and an inlet gas flow rate of 8 L h-1 makes the LSCV/YSZ electrode suitable for use as an potentiometric oxygen sensor electrodes.......A porous composite electrode of La0.8Sr0.2Cr0.97V0.03O3 -delta (LSCV) and yttria-stabilised zirconia (YSZ) was evaluated as a possible candidate for high-temperature potentiometric oxygen sensor measuring electrodes. The oxygen processes at the electrode were characterised by performing...... and 400 nm. At oxygen partial pressures around 0.2 bar at 700º C, the oxygen reaction is dominated by solid-state diffusion of oxide ions and surface reaction kinetics. At oxygen partial pressures around 10-5 bar above 800º C, gas phase mass transport processes dominate the impedance spectra...
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Mixing Processes in High-Level Waste Tanks - Final Report
International Nuclear Information System (INIS)
Peterson, P.F.
1999-01-01
The mixing processes in large, complex enclosures using one-dimensional differential equations, with transport in free and wall jets is modeled using standard integral techniques. With this goal in mind, we have constructed a simple, computationally efficient numerical tool, the Berkeley Mechanistic Mixing Model, which can be used to predict the transient evolution of fuel and oxygen concentrations in DOE high-level waste tanks following loss of ventilation, and validate the model against a series of experiments
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Chaillou, Thomas; Lanner, Johanna T
2016-12-01
Reduced oxygen (O 2 ) levels (hypoxia) are present during embryogenesis and exposure to altitude and in pathologic conditions. During embryogenesis, myogenic progenitor cells reside in a hypoxic microenvironment, which may regulate their activity. Satellite cells are myogenic progenitor cells localized in a local environment, suggesting that the O 2 level could affect their activity during muscle regeneration. In this review, we present the idea that O 2 levels regulate myogenesis and muscle regeneration, we elucidate the molecular mechanisms underlying myogenesis and muscle regeneration in hypoxia and depict therapeutic strategies using changes in O 2 levels to promote muscle regeneration. Severe hypoxia (≤1% O 2 ) appears detrimental for myogenic differentiation in vitro, whereas a 3-6% O 2 level could promote myogenesis. Hypoxia impairs the regenerative capacity of injured muscles. Although it remains to be explored, hypoxia may contribute to the muscle damage observed in patients with pathologies associated with hypoxia (chronic obstructive pulmonary disease, and peripheral arterial disease). Hypoxia affects satellite cell activity and myogenesis through mechanisms dependent and independent of hypoxia-inducible factor-1α. Finally, hyperbaric oxygen therapy and transplantation of hypoxia-conditioned myoblasts are beneficial procedures to enhance muscle regeneration in animals. These therapies may be clinically relevant to treatment of patients with severe muscle damage.-Chaillou, T. Lanner, J. T. Regulation of myogenesis and skeletal muscle regeneration: effects of oxygen levels on satellite cell activity. © FASEB.
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Powers, Daryl E; Millman, Jeffrey R; Bonner-Weir, Susan; Rappel, Michael J; Colton, Clark K
2010-01-01
Oxygen level in mammalian cell culture is often controlled by placing culture vessels in humidified incubators with a defined gas phase partial pressure of oxygen (pO(2gas)). Because the cells are consuming oxygen supplied by diffusion, a difference between pO(2gas) and that experienced by the cells (pO(2cell)) arises, which is maximal when cells are cultured in vessels with little or no oxygen permeability. Here, we demonstrate theoretically that highly oxygen-permeable silicone rubber membranes can be used to control pO(2cell) during culture of cells in monolayers and aggregates much more accurately and can achieve more rapid transient response following a disturbance than on polystyrene and fluorinated ethylene-propylene copolymer membranes. Cell attachment on silicone rubber was achieved by physical adsorption of fibronectin or Matrigel. We use these membranes for the differentiation of mouse embryonic stem cells to cardiomyocytes and compare the results with culture on polystyrene or on silicone rubber on top of polystyrene. The fraction of cells that are cardiomyocyte-like increases with decreasing pO(2) only when using oxygen-permeable silicone membrane-based dishs, which contract on silicone rubber but not polystyrene. The high permeability of silicone rubber results in pO(2cell) being equal to pO(2gas) at the tissue-membrane interface. This, together with geometric information from histological sections, facilitates development of a model from which the pO(2) distribution within the resulting aggregates is computed. Silicone rubber membranes have significant advantages over polystyrene in controlling pO(2cell), and these results suggest they are a valuable tool for investigating pO(2) effects in many applications, such as stem cell differentiation. Copyright 2009 American Institute of Chemical Engineers
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High-temperature reaction of ''anisotropic'' pyrolitic graphite with oxygen
International Nuclear Information System (INIS)
Lavrenko, V.A.; Pomytkin, A.P.; Neshpor, V.S.; Vinokur, F.L.
1980-01-01
Investigated is the kinetics of initial interaction stages of highly dense crystalloorientated pyrographite with oxygen. Oxidation was carried out in pure oxygen within 0.1-740 mm Hg pressure range and 500-1100 deg C temperature range. It is stated, that at the temperatures below 700 deg C pyrographite oxidation is subjected to a linear law. Above 700-800 deg C the linear law is preserved only at the initial oxidation stage, then the process is described by a parabolic law. Extension of the linear site is decreased in time with the reduction of oxygen pressure. The reaction has apparent fractional order. Activation energy of pyrogrpahite oxidation by the linear low constitutes approximately 58 kcal/mol within 600-800 deg C range and 14 kcal/mol within 800-1100 deg C range. The apparent activation energy constitutes approximately 13 kcal/mol in the region of correspondence to the parabolic law
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Earth history. Low mid-Proterozoic atmospheric oxygen levels and the delayed rise of animals.
Planavsky, Noah J; Reinhard, Christopher T; Wang, Xiangli; Thomson, Danielle; McGoldrick, Peter; Rainbird, Robert H; Johnson, Thomas; Fischer, Woodward W; Lyons, Timothy W
2014-10-31
The oxygenation of Earth's surface fundamentally altered global biogeochemical cycles and ultimately paved the way for the rise of metazoans at the end of the Proterozoic. However, current estimates for atmospheric oxygen (O2) levels during the billion years leading up to this time vary widely. On the basis of chromium (Cr) isotope data from a suite of Proterozoic sediments from China, Australia, and North America, interpreted in the context of data from similar depositional environments from Phanerozoic time, we find evidence for inhibited oxidation of Cr at Earth's surface in the mid-Proterozoic (1.8 to 0.8 billion years ago). These data suggest that atmospheric O2 levels were at most 0.1% of present atmospheric levels. Direct evidence for such low O2 concentrations in the Proterozoic helps explain the late emergence and diversification of metazoans. Copyright © 2014, American Association for the Advancement of Science.
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Effect of altitude on oxygen binding by hemoglobin and on organic phosphate levels
Lenfant, Claude; Torrance, John; English, Eugenia; Finch, Clement A.; Reynafarje, Cesar; Ramos, Jose; Faura, Jose
1968-01-01
The relationship between oxygen dissociation and 2,3-diphosphoglycerate (2,3-DPG) in the red cell has been studied in subjects moving from low to high altitude and vice versa. Within 24 hr following the change in altitude there was a change in hemoglobin affinity for oxygen; this modification therefore represents an important rapid adaptive mechanism to anoxia. A parallel change occurred in the organic phosphate content of the red cell. While this study does not provide direct evidence of a cause-effect relationship, the data strongly suggest that with anoxia, the observed rise in organic phosphate content of the red cell is responsible for increased availability of oxygen to tissues. Images PMID:5725278
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International Nuclear Information System (INIS)
Hartmann, T.
1996-01-01
In the vitrification process of high-level waste concentrates (HLWC) from the reprocessing of nuclear spent fuel elements, about 30 different elements have to be immobilized in a solid matrix consisting of an alkali borosilicate glass. Most of the waste oxides are dissolved in the alkali borosilicate melt and become structural elements of the glasses when cooled. This, however, applies only partly to the platinum metals Ru, which forms RuO 2 , and palladium and rhodium, which deposit as sparingly soluble and electrically conducting tellurides. This might considerably impair the technical process of HLWC vitrification. Therefore, constitutional studies on the Pd-Rh-Te system became necessary. The phase diagram of the Pd-Rh-Te ternary system at temperatures of 1150, 1100, 1050, 1000, 950, 900 and 750 C was determined under inertial conditions. Oxygen exerts a major influence on the system. Already under limited availability of oxygen, the rhodium contents of the solid solution phases α 1 and α 2 are clearly diminished. Rhodium of the phases becomes oxidized selectively. The three-phase field α 1 +α 2 +L is shifted to higher palladium and tellurium contents, even oxygen is available to a limited extend only. With the oxygen in the air, the extension of the three-phase space is reduced markedly. The complex process chemistry of Pf, Rh and Te during the vitrification can be described by the state of the Pd-Rh-Te ternary system after annealing in (air) oxygen for limited periods of time. (orig./MM) [de
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International Nuclear Information System (INIS)
Nakayama, Norio; Uchida, Shunsuke
1984-01-01
A pressure balanced type membrane covered polarographic oxygen detector was developed to determine directly oxygen concentrations in high temperature, high pressure water without cooling and pressure reducing procedures. The detector is characterized by the following features: (1) The detector body and the membrane for oxygen penetration are made of heat resistant resin. (2) The whole detector body is contained in a pressure chamber where interior and exterior pressures of the detector are balanced. (3) Thermal expansion of the electrolyte is absorbed by deformation of a diaphragm attached to the detector bottom. (4) The effect of dissolved Ag + on the signal current is eliminated by applying a guard electrode. As a result of performance tests at elevated temperature, it was demonstrated that a linear relationship between oxygen concentration and signal current was obtained up to 285 0 C, which was stabilized by the guard electrode. The minimum O 2 concentration detectable was 0.03ppm (9.4 x 10 -7 mol/kg). (author)
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International Nuclear Information System (INIS)
Prikhna, Tatiana; Chaud, Xavier; Gawalek, Wolfgang; Rabier, Jaques; Savchuk, Yaroslav; Joulain, Anne; Vlasenko, Andrey; Moshchil, Viktor; Sergienko, Nina; Dub, Sergey; Melnikov, Vladimir; Litzkendorf, Doris; Habisreuther, Tobias; Sverdun, Vladimir
2007-01-01
The high pressure-high temperature oxygenation of thin-walled MT-YBCO (with artificially produced holes) allows decreasing the amount of macrocracks and increasing j c of the material. The MT-YBCO produced from Y123 and Y211 in the fields higher than 2 T showed higher j c in the ab-planes and lower j c in the c-direction than the MT-YBCO manufactured from Y123 and Y 2 O 3 and can be explained by the difference in twin and microcrack density that in turn can be affected by the difference in Y211 phase distribution
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International Nuclear Information System (INIS)
Di Bari, Chiara; Goñi-Urtiaga, Asier; Pita, Marcos; Shleev, Sergey; Toscano, Miguel D.; Sainz, Raquel; De Lacey, Antonio L.
2016-01-01
High surface area graphene electrodes were prepared by simultaneous electrodeposition and electroreduction of graphene oxide. The electrodeposition process was optimized in terms of pH and conductivity of the solution and the obtained graphene electrodes were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy and electrochemical methods (cyclic voltammetry and impedance spectroscopy). Electrodeposited electrodes were further functionalized to carry out covalent immobilization of two oxygen-reducing multicopper oxidases: laccase and bilirubin oxidase. The enzymatic electrodes were tested as direct electron transfer based biocathodes and catalytic currents as high as 1 mA/cm 2 were obtained. Finally, the mechanism of the enzymatic oxygen reduction reaction was studied for both enzymes calculating the Tafel slopes and transfer coefficients.
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Escape of high-energy oxygen ions through magnetopause reconnection under northward IMF
Directory of Open Access Journals (Sweden)
S. Kasahara
2008-12-01
Full Text Available During a storm recovery phase on 15 May 2005, the Geotail spacecraft repeatedly observed high-energy (>180 keV oxygen ions in the dayside magnetosheath near the equatorial plane. We focused on the time period from 11:20 UT to 13:00 UT, when Geotail observed the oxygen ions and the interplanetary magnetic field (IMF was constantly northward. The magnetic reconnection occurrence northward and duskward of Geotail is indicated by the Walén analysis and convective flows in the magnetopause boundary layer. Anisotropic pitch angle distributions of ions suggest that high-energy oxygen ions escaped from the northward of Geotail along the reconnected magnetic field lines. From the low-energy particle precipitation in the polar cap observed by DMSP, which is consistent with magnetic reconnection occurring between the magnetosheath field lines and the magnetospheric closed field lines, we conclude that these oxygen ions are of ring current origin. Our results thus suggest a new escape route of oxygen ions during northward IMF. In the present event, this escape mechanism is more dominant than the leakage via the finite Larmor radius effect across the dayside equatorial magnetopause.
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IMPACT OF OXYGEN CONCENTRATION ON ZEBRA MUSSEL MORTALITY
Energy Technology Data Exchange (ETDEWEB)
Daniel P. Molloy
2003-01-27
These tests have indicated that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels in environments having dissolved oxygen (DO) concentrations ranging from very low to very high. The results suggest that the highest mussel kill can be achieved in moderately to highly aerated environments, while kill may be 0-20% lower under conditions of very low oxygen. For example, under highly oxygenated conditions 97% kill was achieved while conditions having low DO produced 79% mussel kill. Service water measured in a local power plant indicated that DO concentrations were in the range of 8-9 ppm (e.g., highly aerated) within their pipes. Therefore, we will not expect to see decreases in the efficacy of CL0145A treatments due to oxygen levels within such power plant pipes.
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IMPACT OF OXYGEN CONCENTRATION ON ZEBRA MUSSEL MORTALITY
International Nuclear Information System (INIS)
Molloy, Daniel P.
2003-01-01
These tests have indicated that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels in environments having dissolved oxygen (DO) concentrations ranging from very low to very high. The results suggest that the highest mussel kill can be achieved in moderately to highly aerated environments, while kill may be 0-20% lower under conditions of very low oxygen. For example, under highly oxygenated conditions 97% kill was achieved while conditions having low DO produced 79% mussel kill. Service water measured in a local power plant indicated that DO concentrations were in the range of 8-9 ppm (e.g., highly aerated) within their pipes. Therefore, we will not expect to see decreases in the efficacy of CL0145A treatments due to oxygen levels within such power plant pipes
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Late Archean Surface Ocean Oxygenation (Invited)
Kendall, B.; Reinhard, C.; Lyons, T. W.; Kaufman, A. J.; Anbar, A. D.
2009-12-01
Oxygenic photosynthesis must have evolved by 2.45-2.32 Ga, when atmospheric oxygen abundances first rose above 0.001% present atmospheric level (Great Oxidation Event; GOE). Biomarker evidence for a time lag between the evolution of cyanobacterial oxygenic photosynthesis and the GOE continues to be debated. Geochemical signatures from sedimentary rocks (redox-sensitive trace metal abundances, sedimentary Fe geochemistry, and S isotopes) represent an alternative tool for tracing the history of Earth surface oxygenation. Integrated high-resolution chemostratigraphic profiles through the 2.5 Ga Mt. McRae Shale (Pilbara Craton, Western Australia) suggest a ‘whiff’ of oxygen in the surface environment at least 50 M.y. prior to the GOE. However, the geochemical data from the Mt. McRae Shale does not uniquely constrain the presence or extent of Late Archean ocean oxygenation. Here, we present high-resolution chemostratigraphic profiles from 2.6-2.5 Ga black shales (upper Campbellrand Subgroup, Kaapvaal Craton, South Africa) that provide the earliest direct evidence for an oxygenated ocean water column. On the slope beneath the Campbellrand - Malmani carbonate platform (Nauga Formation), a mildly oxygenated water column (highly reactive iron to total iron ratios [FeHR/FeT] ≤ 0.4) was underlain by oxidizing sediments (low Re and Mo abundances) or mildly reducing sediments (high Re but low Mo abundances). After drowning of the carbonate platform (Klein Naute Formation), the local bottom waters became anoxic (FeHR/FeT > 0.4) and intermittently sulphidic (pyrite iron to highly reactive iron ratios [FePY/FeHR] > 0.8), conducive to enrichment of both Re and Mo in sediments, followed by anoxic and Fe2+-rich (ferruginous) conditions (high FeT, FePY/FeHR near 0). Widespread surface ocean oxygenation is suggested by Re enrichment in the broadly correlative Klein Naute Formation and Mt. McRae Shale, deposited ~1000 km apart in the Griqualand West and Hamersley basins
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Nasal high flow therapy: a novel treatment rather than a more expensive oxygen device
Directory of Open Access Journals (Sweden)
Eleni Ischaki
2017-09-01
Full Text Available Nasal high flow is a promising novel oxygen delivery device, whose mechanisms of action offer some beneficial effects over conventional oxygen systems. The administration of a high flow of heated and humidified gas mixture promotes higher and more stable inspiratory oxygen fraction values, decreases anatomical dead space and generates a positive airway pressure that can reduce the work of breathing and enhance patient comfort and tolerance. Nasal high flow has been used as a prophylactic tool or as a treatment device mostly in patients with acute hypoxaemic respiratory failure, with the majority of studies showing positive results. Recently, its clinical indications have been expanded to post-extubated patients in intensive care or following surgery, for pre- and peri-oxygenation during intubation, during bronchoscopy, in immunocompromised patients and in patients with “do not intubate” status. In the present review, we differentiate studies that suggest an advantage (benefit from other studies that do not suggest an advantage (no benefit compared to conventional oxygen devices or noninvasive ventilation, and propose an algorithm in cases of nasal high flow application in patients with acute hypoxaemic respiratory failure of almost any cause.
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Brotfain, Evgeni; Zlotnik, Alexander; Schwartz, Andrei; Frenkel, Amit; Koyfman, Leonid; Gruenbaum, Shaun E; Klein, Moti
2014-11-01
Optimal oxygen supply is the cornerstone of the management of critically ill patients after extubation, especially in patients at high risk for extubation failure. In recent years, high flow oxygen system devices have offered an appropriate alternative to standard oxygen therapy devices such as conventional face masks and nasal prongs. To assess the clinical effects of high flow nasal cannula (HFNC) compared with standard oxygen face masks in Intensive Care Unit (ICU) patients after extubation. We retrospectively analyzed 67 consecutive ventilated critical care patients in the ICU over a period of 1 year. The patients were allocated to two treatment groups: HFNC (34 patients, group 1) and non-rebreathing oxygen face mask (NRB) (33 patients, group 2). Vital respiratory and hemodynamic parameters were assessed prior to extubation and 6 hours after extubation. The primary clinical outcomes measured were improvement in oxygenation, ventilation-free days, re-intubation, ICU length of stay, and mortality. The two groups demonstrated similar hemodynamic patterns before and after extubation. The respiratory rate was slightly elevated in both groups after extubation with no differences observed between groups. There were no statistically significant clinical differences in PaCO2. However, the use of HFNC resulted in improved PaO2/FiO2 post-extubation (P < 0.05). There were more ventilator-free days in the HFNC group (P< 0.05) and fewer patients required reintubation (1 vs. 6). There were no differences in ICU length of stay or mortality. This study demonstrated better oxygenation for patients treated with HFNC compared with NRB after extubation. HFNC may be more effective than standard oxygen supply devices for oxygenation in the post-extubation period.
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High temperature microcalorimetry. Study of metal-oxygen systems
International Nuclear Information System (INIS)
Tetot, R.; Picard, C.; Boureau, G.; Gerdanian, P.
1981-01-01
Determination of partial molar enthalpy in metal-oxygen systems at 1050 0 C. Three representative systems are studied: the solution of oxygen in titanium, the titanium-oxygen system and the uranium-oxygen system from UOsub(2.00) to UOsub(2.60) [fr
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... their breathing to dangerously low levels. Will I need oxygen when I sleep? Usually if you use supplemental oxygen during the ... your health care provider tells you you only need to use oxygen for exercise or sleep. Even if you feel “fine” off of your ...
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Development of high power chemical oxygen lodine laser
Energy Technology Data Exchange (ETDEWEB)
Kim, Cheol Jung; Choi, Y. D.; Chung, C. M.; Kim, M. S.; Baik, S. H.; Kwon, S. O.; Park, S. K.; Kim, T. S
2001-10-01
This project is directed to construct 10kW Chemical Oxygen Iodine Laser (COIL) for decommissioning of old nuclear facilities, and to get the key technology that can be used for the development of high energy laser weapon. COIL is possible up to MW class in proportion to the amount of chemical reaction. For this reason, high energy laser weapon including Airborne Laser (ABL) and Airborne Tactical Laser (ATL) has been developed as a military use in USA. Recently, many research group have been doing a development study of COIL for nuclear and industrial use in material processing such as cutting and decommissioning by combining laser beam delivery through optical fiber. The Chemical Oxygen Iodine Laser of 6 kW output power has been developed in this project. The main technologies of chemical reaction and supersonic fluid control were developed. This technology can be applied for construction of 10 kW laser system. This laser can be used for old nuclear facilities and heavy industry by combining laser beam delivery through optical fiber. The development of High Energy Laser (HEL) weapon is necessary as a military use, and we conclude that Airborne Tactical Laser should be developed in our country.
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Lin, Chi-Wen; Wu, Chih-Hung; Guo, Pei-Yu; Chang, Shih-Hsien
2017-12-15
Both a low concentration of dissolved oxygen and the toxicity of a high concentration of BTEX inhibit the bioremediation of BTEX in groundwater. A novel method of preparing encapsulated oxygen-releasing beads (encap-ORBs) for the biodegradation of BTEX in groundwater was developed. Experimental results show that the integrality and oxygen-releasing capacity of encap-ORBs exceeded those of ORBs. The use of polyvinyl alcohol (PVA) with high M.W. to prepare encap-ORBs improved their integrality. The encap-ORBs effectively released oxygen for 128 days. High concentration of BTEX (480 mg L -1 ) inhibited the biodegradation by the free cells. Immobilization of degraders in the encap-ORB alleviated the inhibition. Scanning electron microscope analysis reveals that the BTEX degraders grew on the surface of encap-ORB after bioremediation. The above results indicate that the encap-ORBs were effective in the bioremediation of BTEX at high concentration in groundwater. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Oxygen concentration inside a functioning photosynthetic cell.
Kihara, Shigeharu; Hartzler, Daniel A; Savikhin, Sergei
2014-05-06
The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic photosynthetic bacteria in solitary form could have evolved ∼2.8 billion years ago without special mechanisms to protect them against reactive oxygen species. These mechanisms instead could have been developed during the following ∼500 million years while the oxygen level in the Earth's atmosphere was slowly rising. Excess oxygen concentrations within individual cells of the apomorphic cyanobacteria Synechocystis and Synechococcus are 0.064 and 0.25 μM, respectively. These numbers suggest that intramembrane and intracellular proteins in isolated oxygenic photosynthetic cells are not subjected to excessively high oxygen levels. The situation is different for closely packed colonies of photosynthetic cells. Calculations show that the excess concentration within colonies that are ∼40 μm or larger in diameter can be comparable to the oxygen concentration in air-saturated water, suggesting that species forming colonies require protection against reactive oxygen species even in the absence of oxygen in the surrounding atmosphere. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.
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International Space Station (ISS) Oxygen High Pressure Storage Management
Lewis, John R.; Dake, Jason; Cover, John; Leonard, Dan; Bohannon, Carl
2004-01-01
High pressure oxygen onboard the ISS provides support for Extra Vehicular Activities (EVA) and contingency metabolic support for the crew. This high pressure 02 is brought to the ISS by the Space Shuttle and is transferred using the Oxygen Recharge Compressor Assembly (ORCA). There are several drivers that must be considered in managing the available high pressure 02 on the ISS. The amount of O2 the Shuttle can fly up is driven by manifest mass limitations, launch slips, and on orbit Shuttle power requirements. The amount of 02 that is used from the ISS high pressure gas tanks (HPGT) is driven by the number of Shuttle docked and undocked EVAs, the type of EVA prebreath protocol that is used and contingency use of O2 for metabolic support. Also, the use of the ORCA must be managed to optimize its life on orbit and assure that it will be available to transfer the planned amount of O2 from the Shuttle. Management of this resource has required long range planning and coordination between Shuttle manifest on orbit plans. To further optimize the situation hardware options have been pursued.
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Directory of Open Access Journals (Sweden)
Olivier eDupuy
2015-02-01
Full Text Available Aim: Many studies have suggested that physical exercise training improves cognition and more selectively executive functions. There is a growing interest to clarify the neurophysiological mechanisms that underlie this effect. The aim of the current study was to evaluate the neurophysiological changes in cerebral oxygenation associated with physical fitness level and executive functions. Method: In this study, 22 younger and 36 older women underwent a maximal graded continuous test (i.e., O2max in order to classifyassign them into a fitness group (higher vs. lower fit. All participants completed neuropsychological paper and pencil testing and a computerized Stroop task (which contained executive and non-executive conditions in which the change in pPrefrontal cortex oxygenation change was evaluated in all participants with a near infrared spectroscopy (NIRS. system during a computerized Stroop task (which contains executive and non-executive conditions. Results: Our findings revealed a Fitness x Condition interaction (p < .05 such that higher fit women scored better on measures of executive functions than lower fit women. In comparison to lower fit women, higher fit women had faster reaction times in the switching (executiveExecutive condition of the computerized Stroop task. No significant effect was observed ion the non-executive condition of the test and no interactions were found with age. In measures of cerebral oxygenation (ΔHbT and ΔHbO2, we found a main effect of fitness on cerebral oxygenation during the Stroop task such that only high fit women demonstrated a significant increase in the right inferior frontal gyrus. Discussion/Conclusion:Higher fit individuals who demonstrate better cardiorespiratory functions (as measured by O2max show faster reaction times and greater cerebral oxygenation in the right inferior frontal gyrus than women with lower fitness levels. The lack of interaction with age, suggests that good
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Energy Technology Data Exchange (ETDEWEB)
Moreno, J.B.
1983-07-01
A field test of an oxygen/diesel fuel, direct contact steam generator has been completed. The field test, which was a part of Project DEEP STEAM and was sponsored by the US Department of Energy, involved the thermal stimulation of a well pattern in the Tar Zone of the Wilmington Oil Field. The activity was carried out in cooperation with the City of Long Beach and the Long Beach Oil Development Company. The steam generator was operated at ground level, with the steam and combustion products delivered to the reservoir through 2022 feet of calcium-silicate insulated tubing. The objectives of the test included demonstrations of safety, operational ease, reliability and lifetime; investigations of reservoir response, environmental impact, and economics; and comparison of those points with a second generator that used air rather than oxygen. The test was extensively instrumented to provide the required data. Excluding interruptions not attributable to the oxygen/diesel system, steam was injected 78% of the time. System lifetime was limited by the combustor, which required some parts replacement every 2 to 3 weeks. For the conditions of this particular test, the use of trucked-in LOX resulted in liess expense than did the production of the equivalent amount of high pressure air using on site compressors. No statistically significant production change in the eight-acre oxygen system well pattern occurred during the test, nor were any adverse effects on the reservoir character detected. Gas analyses during the field test showed very low levels of SOX (less than or equal to 1 ppM) in the generator gaseous effluent. The SOX and NOX data did not permit any conclusion to be drawn regarding reservoir scrubbing. Appreciable levels of CO (less than or equal to 5%) were measured at the generator, and in this case produced-gas analyses showed evidence of significant gas scrubbing. 64 figures, 10 tables.
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Energy Technology Data Exchange (ETDEWEB)
Prikhna, Tatiana [Institute for Superhard Materials, 2 Avtozavodskaya Street, Kiev 04074 (Ukraine)], E-mail: prikhna@iptelecom.net.ua; Chaud, Xavier [CNRS/CRETA, 25, Avenue des Martyrs BP 166, 38042 Grenoble, Cedex 9 (France); Gawalek, Wolfgang [Institut fuer Physikalische Hochtechnologie, Albert-Einstein-Strasse 9, Jena (Germany); Rabier, Jaques [Universite de Poitiers, CNRS/Lab. de Metallurgie Physique, UMR 6630 CNRS-Universite de Poitiers SP2MI, BP 30179, F-86962 Chasseneuil Futuroscope Cedex (France); Savchuk, Yaroslav [Institute for Superhard Materials, 2 Avtozavodskaya Street, Kiev 04074 (Ukraine); Joulain, Anne [Universite de Poitiers, CNRS/Lab. de Metallurgie Physique, UMR 6630 CNRS-Universite de Poitiers SP2MI, BP 30179, F-86962 Chasseneuil Futuroscope Cedex (France); Vlasenko, Andrey; Moshchil, Viktor; Sergienko, Nina; Dub, Sergey; Melnikov, Vladimir [Institute for Superhard Materials, 2 Avtozavodskaya Street, Kiev 04074 (Ukraine); Litzkendorf, Doris; Habisreuther, Tobias [Institut fuer Physikalische Hochtechnologie, Albert-Einstein-Strasse 9, Jena (Germany); Sverdun, Vladimir [Institute for Superhard Materials, 2 Avtozavodskaya Street, Kiev 04074 (Ukraine)
2007-09-01
The high pressure-high temperature oxygenation of thin-walled MT-YBCO (with artificially produced holes) allows decreasing the amount of macrocracks and increasing j{sub c} of the material. The MT-YBCO produced from Y123 and Y211 in the fields higher than 2 T showed higher j{sub c} in the ab-planes and lower j{sub c} in the c-direction than the MT-YBCO manufactured from Y123 and Y{sub 2}O{sub 3} and can be explained by the difference in twin and microcrack density that in turn can be affected by the difference in Y211 phase distribution.
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Jaworske, D. A.; Degroh, Kim K.; Podojil, G.; McCollum, T.; Anzic, J.
1992-11-01
Pinholes or other defect sites in a protective oxide coating provide pathways for atomic oxygen in low Earth orbit to reach underlying material. One concept of enhancing the lifetime of materials in low Earth orbit is to apply a leveling coating to the material prior to applying any reflective and protective coatings. Using a surface tension leveling coating concept, a low viscosity epoxy was applied to the surface of several composite coupons. A protective layer of 1000 A of SiO2 was deposited on top of the leveling coating, and the coupons were exposed to an atomic oxygen environment in a plasma asher. Pinhole populations per unit area were estimated by counting the number of undercut sites observed by scanning electron microscopy. Defect density values of 180,000 defects/sq cm were reduced to about 1000 defects/sq cm as a result of the applied leveling coating. These improvements occur at a mass penalty of about 2.5 mg/sq cm.
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High-Flow Nasal Interface Improves Oxygenation in Patients Undergoing Bronchoscopy
Directory of Open Access Journals (Sweden)
Umberto Lucangelo
2012-01-01
Full Text Available During bronchoscopy hypoxemia is commonly found and oxygen supply can be delivered by interfaces fed with high gas flows. Recently, the high-flow nasal cannula (HFNC has been introduced for oxygen therapy in adults, but they have not been used so far during bronchoscopy in adults. Forty-five patients were randomly assigned to 3 groups receiving oxygen: 40 L/min through a Venturi mask (V40, N=15, nasal cannula (N40, N=15, and 60 L/min through a nasal cannula (N60, N=15 during bronchoscopy. Gas exchange and circulatory variables were sampled before (FiO2 = 0.21, at the end of bronchoscopy (FiO2 = 0.5, and thereafter (V40, FiO2 = 0.35. In 8 healthy volunteers oxygen was randomly delivered according to V40, N40, and N60 settings, and airway pressure was measured. At the end of bronchoscopy, N60 presented higher PaO2, PaO2/FiO2, and SpO2 than V40 and N40 that did not differ between them. In the volunteers (N60 median airway pressure amounted to 3.6 cmH2O. Under a flow rate of 40 L/min both the Venturi mask and HFNC behaved similarly, but nasal cannula associated with a 60 L/min flow produced the better results, thus indicating its use in mild respiratory dysfunctions.
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Oxygen stoichiometry and the high Tc superconducting oxides
International Nuclear Information System (INIS)
Tarascon, J.M.; Bagley, B.G.
1989-01-01
Methods for determining the oxygen content in high Tc materials, such as thermogravimetric analysis and chemical analysis, are discussed. Consideration is given to La-based cuprates, Y-based cuprates, and Bi-based cuprates. Superconducting transition temperatures are analyzed as a function of the Cu(1)-O(4) bond lengths for several different compositions in the Y-based system. 28 references
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Bosch Reactor Development for High Percentage Oxygen Recovery from Carbon Dioxide
Howard, David; Abney, Morgan
2015-01-01
This next Generation Life Support Project entails the development and demonstration of Bosch reaction technologies to improve oxygen recovery from metabolically generated oxygen and/or space environments. A primary focus was placed on alternate carbon formation reactor concepts to improve useful catalyst life for space vehicle applications, and make use of in situ catalyst resources for non-terrestrial surface missions. Current state-of-the-art oxygen recovery systems onboard the International Space Station are able to effectively recover approximately 45 percent of the oxygen consumed by humans and exhausted in the form of carbon dioxide (CO2). Excess CO2 is vented overboard and the oxygen contained in the molecules is lost. For long-duration missions beyond the reaches of Earth for resupply, it will be necessary to recover greater amounts of constituents such as oxygen that are necessary for sustaining life. Bosch technologies theoretically recover 100 percent of the oxygen from CO2, producing pure carbon as the sole waste product. Challenges with this technology revolve around the carbon product fouling catalyst materials, drastically limiting catalyst life. This project successfully demonstrated techniques to extend catalyst surface area exposure times to improve catalyst life for vehicle applications, and demonstrated the use of Martian and lunar regolith as viable catalyst Bosch Reactor Development for High Percentage Oxygen Recovery From Carbon Dioxide materials for surface missions. The Bosch process generates carbon nanotube formation within the regolith, which has been shown to improve mechanical properties of building materials. Production of bricks from post reaction regolith for building and radiation shielding applications were also explored.
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Mixed oxygen ion/electron-conducting ceramics for oxygen separation
Energy Technology Data Exchange (ETDEWEB)
Stevenson, J.W.; Armstrong, T.R.; Armstrong, B.L. [Pacific Northwest National Lab., Richland, WA (United States)
1996-08-01
Mixed oxygen ion and electron-conducting ceramics are unique materials that can passively separate high purity oxygen from air. Oxygen ions move through a fully dense ceramic in response to an oxygen concentration gradient, charge-compensated by an electron flux in the opposite direction. Compositions in the system La{sub 1{minus}x}M{sub x}Co{sub 1{minus}y{minus}z}Fe{sub y}N{sub z}O{sub 3{minus}{delta}}, perovskites where M=Sr, Ca, and Ba, and N=Mn, Ni, Cu, Ti, and Al, have been prepared and their electrical, oxygen permeation, oxygen vacancy equilibria, and catalytic properties evaluated. Tubular forms, disks, and asymmetric membrane structures, a thin dense layer on a porous support of the same composition, have been fabricated for testing purposes. In an oxygen partial gradient, the passive oxygen flux through fully dense structures was highly dependent on composition. An increase in oxygen permeation with increased temperature is attributed to both enhanced oxygen vacancy mobility and higher vacancy populations. Highly acceptor-doped compositions resulted in oxygen ion mobilities more than an order of magnitude higher than yttria-stabilized zirconia. The mixed conducting ceramics have been utilized in a membrane reactor configuration to upgrade methane to ethane and ethylene. Conditions were established to balance selectivity and throughput in a catalytic membrane reactor constructed from mixed conducting ceramics.
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Search for Fractionally Charged Nuclei in High-Energy Oxygen-Lead Collisions
2002-01-01
We propose to use stacks of CR-39 plastic track detectors to look for fractionally charged projectile fragments produced in collisions of high-energy oxygen, sulfur, and calcium nuclei with a lead target. The expected charge resolution is @s^z~=~0.06e for fragments with 17e/3~@$<$~Z~@$<$~23e/3. We request that two target + stack assemblies be exposed to 1~x~10|5 oxygen nuclei at maximum available energy.
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Gagnon, Louis; Smith, Amy F; Boas, David A; Devor, Anna; Secomb, Timothy W; Sakadžić, Sava
2016-01-01
Oxygen is delivered to brain tissue by a dense network of microvessels, which actively control cerebral blood flow (CBF) through vasodilation and contraction in response to changing levels of neural activity. Understanding these network-level processes is immediately relevant for (1) interpretation of functional Magnetic Resonance Imaging (fMRI) signals, and (2) investigation of neurological diseases in which a deterioration of neurovascular and neuro-metabolic physiology contributes to motor and cognitive decline. Experimental data on the structure, flow and oxygen levels of microvascular networks are needed, together with theoretical methods to integrate this information and predict physiologically relevant properties that are not directly measurable. Recent progress in optical imaging technologies for high-resolution in vivo measurement of the cerebral microvascular architecture, blood flow, and oxygenation enables construction of detailed computational models of cerebral hemodynamics and oxygen transport based on realistic three-dimensional microvascular networks. In this article, we review state-of-the-art optical microscopy technologies for quantitative in vivo imaging of cerebral microvascular structure, blood flow and oxygenation, and theoretical methods that utilize such data to generate spatially resolved models for blood flow and oxygen transport. These "bottom-up" models are essential for the understanding of the processes governing brain oxygenation in normal and disease states and for eventual translation of the lessons learned from animal studies to humans.
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Luo, Junming; Tang, Haibo; Tian, Xinlong; Hou, Sanying; Li, Xiuhua; Du, Li; Liao, Shijun
2018-01-31
The severe dissolution of the cathode catalyst, caused by an undesired oxygen reduction reaction at the anode during startup and shutdown, is a fatal challenge to practical applications of polymer electrolyte membrane fuel cells. To address this important issue, according to the distinct structure-sensitivity between the σ-type bond in H 2 and the π-type bond in O 2 , we design a HD-Pt/TiN material by highly dispersing Pt on the TiN surface to inhibit the unwanted oxygen reduction reaction. The highly dispersed Pt/TiN catalyst exhibits excellent selectivity toward hydrogen oxidation and oxygen reduction reactions. With a Pt loading of 0.88 wt %, our catalyst shows excellent hydrogen oxidation reaction activity, close to that of commercial 20 wt % Pt/C catalyst, and much lower oxygen reduction reaction activity than the commercial 20 wt % Pt/C catalyst. The lack of well-ordered Pt facets is responsible for the excellent selectivity of the HD-Pt/TiN materials toward hydrogen oxidation and oxygen reduction reactions. Our work provides a new and cost-effective solution to design selective catalysts toward hydrogen oxidation and oxygen reduction reactions, making the strategy of using oxygen-tolerant anode catalyst to improve the stability of polymer electrolyte membrane fuel cells during startup and shutdown more affordable and practical.
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Environmentally-assisted cracking behavior of a high level nuclear waste container alloy
International Nuclear Information System (INIS)
James, L.A.; Duncan, D.R.
1987-06-01
The environmentally assisted cracking behavior of cast American Society for Testing and Materials A27 steel in a simulated groundwater environment was studied using both statically loaded and cyclically loaded specimens. Compared to other aqueous environments, the groundwater environment is relatively nonaggressive, probably because of its high pH and low level of dissolved oxygen. 18 refs., 5 figs., 1 tab
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International Nuclear Information System (INIS)
Jantzen, Kim; Møller, Peter; Karottki, Dorina Gabriela; Olsen, Yulia; Bekö, Gabriel; Clausen, Geo; Hersoug, Lars-Georg; Loft, Steffen
2016-01-01
Exposure to particles in the fine and ultrafine size range has been linked to induction of low-grade systemic inflammation, oxidative stress and development of cardiovascular diseases. Declining levels of endothelial progenitor cells within systemic circulation have likewise been linked to progression of cardiovascular diseases. The objective was to determine if exposure to fine and ultrafine particles from indoor and outdoor sources, assessed by personal and residential indoor monitoring, is associated with altered levels of endothelial progenitor cells, and whether such effects are related to leukocyte-mediated oxidative stress. The study utilized a cross sectional design performed in 58 study participants from a larger cohort. Levels of circulating endothelial progenitor cells, defined as either late (CD34 + KDR + cells) or early (CD34 + CD133 + KDR + cells) subsets were measured using polychromatic flow cytometry. We additionally measured production of reactive oxygen species in leukocyte subsets (lymphocytes, monocytes and granulocytes) by flow cytometry using intracellular 2′,7′-dichlorofluoroscein. The measurements encompassed both basal levels of reactive oxygen species production and capacity for reactive oxygen species production for each leukocyte subset. We found that the late endothelial progenitor subset was negatively associated with levels of ultrafine particles measured within the participant residences and with reactive oxygen species production capacity in lymphocytes. Additionally, the early endothelial progenitor cell levels were positively associated with a personalised measure of ultrafine particle exposure and negatively associated with both basal and capacity for reactive oxygen species production in lymphocytes and granulocytes, respectively. Our results indicate that exposure to fine and ultrafine particles derived from indoor sources may have adverse effects on human vascular health.
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Formation of SIMOX–SOI structure by high-temperature oxygen implantation
International Nuclear Information System (INIS)
Hoshino, Yasushi; Kamikawa, Tomohiro; Nakata, Jyoji
2015-01-01
We have performed oxygen ion implantation in silicon at very high substrate-temperatures (⩽1000 °C) for the purpose of forming silicon-on-insulator (SOI) structure. We have expected that the high-temperature implantation can effectively avoids ion-beam-induced damages in the SOI layer and simultaneously stabilizes the buried oxide (BOX) and SOI-Si layer. Such a high-temperature implantation makes it possible to reduce the post-implantation annealing temperature. In the present study, oxygen ions with 180 keV are incident on Si(0 0 1) substrates at various temperatures from room temperature (RT) up to 1000 °C. The ion-fluencies are in order of 10"1"7–10"1"8 ions/cm"2. Samples have been analyzed by atomic force microscope, Rutherford backscattering, and micro-Raman spectroscopy. It is found in the AFM analysis that the surface roughness of the samples implanted at 500 °C or below are significantly small with mean roughness of less than 1 nm, and gradually increased for the 800 °C-implanted sample. On the other hand, a lot of dents are observed for the 1000 °C-implanted sample. RBS analysis has revealed that stoichiometric SOI-Si and BOX-SiO_2 layers are formed by oxygen implantation at the substrate temperatures of RT, 500, and 800 °C. However, SiO_2-BOX layer has been desorbed during the implantation. Raman spectra shows that the ion-beam-induced damages are fairly suppressed by such a high-temperatures implantation.
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Energy Technology Data Exchange (ETDEWEB)
James, Garth A. [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Ge Zhao, Alice [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Usui, Marcia [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Underwood, Robert A. [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Nguyen, Hung [The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman Washington; Beyenal, Haluk [The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman Washington; deLancey Pulcini, Elinor [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Agostinho Hunt, Alessandra [Department of Microbiology and Molecular Genetics, 5180 Biomedical and Physical Sciences, Michigan State University, East Lansing Michigan; Bernstein, Hans C. [Pacific Northwest National Laboratory, Chemical and Biological Signature Science, Richland Washington; Fleckman, Philip [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Olerud, John [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Williamson, Kerry S. [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Franklin, Michael J. [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Stewart, Philip S. [Center for Biofilm Engineering, Montana State University, Bozeman Montana
2016-02-16
Polymicrobial biofilms have been implicated in delayed wound healing, although the mechanisms by which biofilms impair wound healing are poorly understood. Many species of bacteria produce exotoxins and exoenzymes that may inhibit healing. In addition, oxygen consumption by biofilms may impede wound healing. In this study, we used oxygen microsensors to measure oxygen transects through in vitro-cultured biofilms, biofilms formed in vivo in a diabetic (db/db) mouse model, and ex vivo human chronic wound specimens. The results show that oxygen levels within both euthanized and live mouse wounds had steep gradients that reached minima ranging from 19 to 61% oxygen partial pressure, compared to atmospheric oxygen levels. The oxygen gradients in the mouse wounds were similar to those observed for clinical isolates cultured in vitro and for human ex vivo scabs. No oxygen gradients were observed for heat-killed scabs, suggesting that active metabolism by the viable bacteria contributed to the reduced oxygen partial pressure of the wounds. To characterize the metabolic activities of the bacteria in the mouse wounds, we performed transcriptomics analyses of Pseudomonas aeruginosa biofilms associated with the db/db mice wounds using Affymetrix microarrays. The results demonstrated that the bacteria expressed genes for metabolic activities associated with cell growth. Interestingly, the transcriptome results indicated that the bacteria within the wounds also experienced oxygen-limitation stress. Among the bacterial genes that were expressed in vivo were genes associated with the Anr-mediated hypoxia-stress response. Other bacterial stress response genes highly expressed in vivo were genes associated with stationary-phase growth, osmotic stress, and RpoH-mediated heat shock stress. Overall, the results support the hypothesis that the metabolic activities of bacteria in biofilms act as oxygen sinks in chronic wounds and that the depletion of oxygen contributes to the
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Roder, H. M.
1974-01-01
Information is presented on instrumentation for density measurement, liquid level measurement, quantity gauging, and phase measurement. Coverage of existing information directly concerned with oxygen was given primary emphasis. A description of the physical principle of measurement for each instrumentation type is included. The basic materials of construction are listed if available from the source document for each instrument discussed. Cleaning requirements, procedures, and verification techniques are included.
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Effect of high hydrostatic pressure on small oxygen-related clusters in silicon: LVM studies
International Nuclear Information System (INIS)
Murin, L.I.; Lindstroem, J.L.; Misiuk, A.
2003-01-01
Local vibrational mode (LVM) spectroscopy is used to explore the effect of high hydrostatic pressure (HP) on the formation of small oxygen-related clusters (dimers, trimers, thermal donors, and C-O complexes) at 450 deg. C and 650 deg. C in Cz-Si crystals with different impurity content and prehistory. It is found, in agreement with previous studies, that HP enhances the oxygen clustering in Cz-Si at elevated temperatures. The effect of HP is related mainly to enhancement in the diffusivity of single oxygen atoms and small oxygen aggregates. HP does not noticeably increase the binding energies of the most simple oxygen related complexes like O 2i , C s O ni . The biggest HP effect on the thermal double donor (TDDs) generation is revealed in hydrogenated samples. Heat-treatment of such samples at 450 deg. C under HP results in extremely high TDD introduction rates as well as in a strong increase in the concentration of the first TDD species
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Salehmin, M N I; Annuar, M S M; Chisti, Y
2013-11-01
This review is focused on the production of microbial lipases by high cell density fermentation. Lipases are among the most widely used of the enzyme catalysts. Although lipases are produced by animals and plants, industrial lipases are sourced almost exclusively from microorganisms. Many of the commercial lipases are produced using recombinant species. Microbial lipases are mostly produced by batch and fed-batch fermentation. Lipases are generally secreted by the cell into the extracellular environment. Thus, a crude preparation of lipases can be obtained by removing the microbial cells from the fermentation broth. This crude cell-free broth may be further concentrated and used as is, or lipases may be purified from it to various levels. For many large volume applications, lipases must be produced at extremely low cost. High cell density fermentation is a promising method for low-cost production: it allows a high concentration of the biomass and the enzyme to be attained rapidly and this eases the downstream recovery of the enzyme. High density fermentation enhances enzyme productivity compared with the traditional submerged culture batch fermentation. In production of enzymes, a high cell density is generally achieved through fed-batch operation, not through perfusion culture which is cumbersome. The feeding strategies used in fed-batch fermentations for producing lipases and the implications of these strategies are discussed. Most lipase-producing microbial fermentations require oxygen. Oxygen transfer in such fermentations is discussed.
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Wang, Zhandong
2017-11-28
Decades of research on the autooxidation of organic compounds have provided fundamental and practical insights into these processes; however, the structure of many key autooxidation intermediates and the reactions leading to their formation still remain unclear. This work provides additional experimental evidence that highly oxygenated intermediates with one or more hydroperoxy groups are prevalent in the autooxidation of various oxygenated (e.g., alcohol, aldehyde, keto compounds, ether, and ester) and nonoxygenated (e.g., normal alkane, branched alkane, and cycloalkane) organic compounds. These findings improve our understanding of autooxidation reaction mechanisms that are routinely used to predict fuel ignition and oxidative stability of liquid hydrocarbons, while also providing insights relevant to the formation mechanisms of tropospheric aerosol building blocks. The direct observation of highly oxygenated intermediates for the autooxidation of alkanes at 500–600 K builds upon prior observations made in atmospheric conditions for the autooxidation of terpenes and other unsaturated hydrocarbons; it shows that highly oxygenated intermediates are stable at conditions above room temperature. These results further reveal that highly oxygenated intermediates are not only accessible by chemical activation but also by thermal activation. Theoretical calculations on H-atom migration reactions are presented to rationalize the relationship between the organic compound’s molecular structure (n-alkane, branched alkane, and cycloalkane) and its propensity to produce highly oxygenated intermediates via extensive autooxidation of hydroperoxyalkylperoxy radicals. Finally, detailed chemical kinetic simulations demonstrate the influence of these additional reaction pathways on the ignition of practical fuels.
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Wang, Zhandong; Popolan-Vaida, Denisia M.; Chen, Bingjie; Moshammer, Kai; Mohamed, Samah; Wang, Heng; Sioud, Salim; Raji, Misjudeen; Kohse-Hö inghaus, Katharina; Hansen, Nils; Dagaut, Philippe; Leone, Stephen R.; Sarathy, Mani
2017-01-01
Decades of research on the autooxidation of organic compounds have provided fundamental and practical insights into these processes; however, the structure of many key autooxidation intermediates and the reactions leading to their formation still remain unclear. This work provides additional experimental evidence that highly oxygenated intermediates with one or more hydroperoxy groups are prevalent in the autooxidation of various oxygenated (e.g., alcohol, aldehyde, keto compounds, ether, and ester) and nonoxygenated (e.g., normal alkane, branched alkane, and cycloalkane) organic compounds. These findings improve our understanding of autooxidation reaction mechanisms that are routinely used to predict fuel ignition and oxidative stability of liquid hydrocarbons, while also providing insights relevant to the formation mechanisms of tropospheric aerosol building blocks. The direct observation of highly oxygenated intermediates for the autooxidation of alkanes at 500–600 K builds upon prior observations made in atmospheric conditions for the autooxidation of terpenes and other unsaturated hydrocarbons; it shows that highly oxygenated intermediates are stable at conditions above room temperature. These results further reveal that highly oxygenated intermediates are not only accessible by chemical activation but also by thermal activation. Theoretical calculations on H-atom migration reactions are presented to rationalize the relationship between the organic compound’s molecular structure (n-alkane, branched alkane, and cycloalkane) and its propensity to produce highly oxygenated intermediates via extensive autooxidation of hydroperoxyalkylperoxy radicals. Finally, detailed chemical kinetic simulations demonstrate the influence of these additional reaction pathways on the ignition of practical fuels.
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Hentz, F; Kozloski, G V; Zeni, D; Brun, M V; Stefanello, S
2017-02-01
Four Polwarth castrated male sheep (42 ± 4.4 kg live weight (LW) surgically implanted with chronic indwelling catheters into the mesenteric, portal and hepatic veins, housed in metabolism cages and offered Cynodon sp. hay at rates (g of dry matter (DM)/kg LW) of 7, 14, 21 or ad libitum, were used in a 4 × 4 Latin square experiment to evaluate the effect of the level of forage intake on blood flow and oxygen consumption by the portal-drained viscera (PDV), liver and total splanchnic tissues (ST). The portal blood flow and the oxygen consumption by PDV linearly increased at increased organic matter (OM) intake. No effect of level of OM intake was obtained for the hepatic artery blood flow and oxygen consumption by liver. As a consequence, the level of OM intake only tended to directly affect hepatic blood flow and oxygen consumption by total ST. Oxygen consumption was linearly and positively related to blood flow across PDV, liver and total ST. The heat production by PDV and total ST, as proportion of metabolizable energy (ME) intake, decreased curvilinearly at increased ME intake. In conclusion, the oxygen consumption by PDV, but not by liver, was directly related to the level of forage intake by sheep. Moreover, when ingested at levels below maintenance, most of ME was spent as heat produced by ST. Journal of Animal Physiology and Animal Nutrition © 2016 Blackwell Verlag GmbH.
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Lavoute, Cécile; Weiss, Michel; Risso, Jean-Jacques; Rostain, Jean-Claude
2014-02-01
The purpose of this study was to investigate the change in the striatal dopamine (DA) level in freely-moving rat exposed to different partial pressure of oxygen (from 1 to 5 ATA). Some works have suggested that DA release by the substantia nigra pars compacta (SNc) neurons in the striatum could be disturbed by hyperbaric oxygen (HBO) exposure, altering therefore the basal ganglia activity. Such changes could result in a change in glutamatergic and GABAergic control of the dopaminergic neurons into the SNc. Such alterations could provide more information about the oxygen-induced seizures observed at 5 ATA in rat. DA-sensitive electrodes were implanted into the striatum under general anesthesia. After 1 week rest, awaked rats were exposed to oxygen-nitrogen mixture at a partial pressure of oxygen of 1, 2, 3, 4 and 5 ATA. DA level was monitored continuously (every 3 min) by in vivo voltammetry before and during HBO exposure. HBO induced a decrease in DA level in relationship to the increase in partial pressure of oxygen from 1 ATA to 4 ATA (-15 % at 1 ATA, -30 % at 2 ATA, -40 % at 3 ATA, -45 % at 4 ATA), without signs of oxygen toxicity. At 5 ATA, DA level strongly decreases (-75 %) before seizure which occurred after 27 min ± 7 HBO exposure. After the epileptic seizure the decrease in DA level disappeared. These changes and the biphasic effect of HBO were discussed in function of HBO action on neurochemical regulations of the nigro striatal pathway.
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Jaswal, Rajeshwer S.; Yaseen, Mohammad A.; Fu, Buyin; Boas, David A.; Sakadžic, Sava
2016-03-01
Due to a lack of imaging tools for high-resolution imaging of cortical tissue oxygenation, the detailed maps of the oxygen partial pressure (PO2) around arterioles, venules, and capillaries remain largely unknown. Therefore, we have limited knowledge about the mechanisms that secure sufficient oxygen delivery in microvascular domains during brain activation, and provide some metabolic reserve capacity in diseases that affect either microvascular networks or the regulation of cerebral blood flow (CBF). To address this challenge, we applied a Two-Photon PO2 Microscopy to map PO2 at different depths in mice cortices. Measurements were performed through the cranial window in the anesthetized healthy mice as well as in the mouse models of microvascular dysfunctions. In addition, microvascular morphology was recorded by the two-photon microscopy at the end of each experiment and subsequently segmented. Co-registration of the PO2 measurements and exact microvascular morphology enabled quantification of the tissue PO2 dependence on distance from the arterioles, capillaries, and venules at various depths. Our measurements reveal significant spatial heterogeneity of the cortical tissue PO2 distribution that is dominated by the high oxygenation in periarteriolar spaces. In cases of impaired oxygen delivery due to microvascular dysfunction, significant reduction in tissue oxygenation away from the arterioles was observed. These tissue domains may be the initial sites of cortical injury that can further exacerbate the progression of the disease.
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International Nuclear Information System (INIS)
Dinguizli, M; Beghein, N; Gallez, B
2008-01-01
Tissue oxygenation is a crucial parameter in various physiopathological situations and can influence the therapeutic response of tumours. EPR oximetry is a reliable method for assessing and monitoring oxygen levels in vivo over long periods of time. Among the different paramagnetic oxygen sensors available for EPR oximetry, lithium phthalocyanine (LiPc) is a serious candidate for in vivo applications because of its narrow linewidth and its high signal-to-noise ratio. To enhance the biocompatibility of the sensors, fluoropolymer Teflon AF2400 was used to make cylindrical micro-inserts containing LiPc crystals. This new micro-pellet design has several advantages for in vivo studies, including the possibility of being able to choose the implant size, a high sensor content, the facility of in vivo insertion and complete protection with preservation of the oxygen sensor's characteristics. The response to oxygen and the kinetics of this response were tested using in vivo EPR: no differences were observed between micro-inserts and uncoated LiPc crystals. Pellets implanted in vivo in muscles conserved their responsiveness over a long period of time (∼two months), which is much longer than the few days of stability observed using LiPc crystals without protection by the implant. Finally, evaluation of the biocompatibility of the implants revealed no inflammatory reaction around the implantation area
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Determination of oxygen content in high Tc superconductors by deuteron particle activation analysis
International Nuclear Information System (INIS)
Tao Zhenlan; Yao, Y.D.; Kao, Y.H.
1993-01-01
The experimental method for determining the oxygen content in high T c superconductors is described in detail. This method is applied to determination of oxygen content in high T c Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O samples in which the stoichiometry is varied by reducing the copper and bismuth concentrations. The oxygen concentration is found to vary linearly with Cu(x = 0-0.2) and Bi (x = 0-0.4) deficiencies in YBa 2 Cu 3(1-x )O y and Bi 2(1-x) Sr 2 CaCu 2 O y respectively. X-ray powder diffraction measurements show that the compound of YBa 2 Cu 3(1-x) O y is orthorhombic in the variation range of x = 0-0.2
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Lv, Lin; Zha, Dace; Ruan, Yunjun; Li, Zhishan; Ao, Xiang; Zheng, Jie; Jiang, Jianjun; Chen, Hao Ming; Chiang, Wei-Hung; Chen, Jun; Wang, Chundong
2018-03-27
Oxygen is the most abundant element in the Earth's crust. The oxygen reduction reaction (ORR) is also the most important reaction in life processes and energy converting/storage systems. Developing techniques toward high-efficiency ORR remains highly desired and a challenge. Here, we report a N-doped carbon (NC) encapsulated CeO 2 /Co interfacial hollow structure (CeO 2 -Co-NC) via a generalized strategy for largely increased oxygen species adsorption and improved ORR activities. First, the metallic Co nanoparticles not only provide high conductivity but also serve as electron donors to largely create oxygen vacancies in CeO 2 . Second, the outer carbon layer can effectively protect cobalt from oxidation and dissociation in alkaline media and as well imparts its higher ORR activity. In the meanwhile, the electronic interactions between CeO 2 and Co in the CeO 2 /Co interface are unveiled theoretically by density functional theory calculations to justify the increased oxygen absorption for ORR activity improvement. The reported CeO 2 -Co-NC hollow nanospheres not only exhibit decent ORR performance with a high onset potential (922 mV vs RHE), half-wave potential (797 mV vs RHE), and small Tafel slope (60 mV dec -1 ) comparable to those of the state-of-the-art Pt/C catalysts but also possess long-term stability with a negative shift of only 7 mV of the half-wave potential after 2000 cycles and strong tolerance against methanol. This work represents a solid step toward high-efficient oxygen reduction.
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International Nuclear Information System (INIS)
Chu, Cheng-Shane; Chuang, Chih-Yung
2014-01-01
A simple, low-cost technique for fabrication of highly sensitive fiber-optic oxygen sensor is described. An organically modified silicate (ORMOSIL) as a matrix for the fabrication of oxygen sensing film was produced. The technique is based on coating the end of a plastic optical fiber with ormosil composite xerogel film sequestered with luminophore palladium (II) meso-tetra(4-carboxyphenyl)porphyrin (PdTCPP) prepared by a sol–gel process. The composite xerogel studied is tetraethylorthosilane (TEOS)/n-octyltriethoxysilane (Octyl-triEOS). Result shows that, expect for PdTCPP-doped TEOS/Octyl-triEOS composite xerogel show the high sensitivity and linear Stern–Volmer relationship which indicate the homogenous environment of the luminophore. The sensitivity of the optical oxygen sensor is quantified in terms of the ratio I N2 /I O2 , where I N2 and I O2 represent the detected fluorescence intensities in pure nitrogen and pure oxygen environments, respectively. The experimental result reveals that the PdTCPP-doped TEOS/Octyl-triEOS oxygen sensor has sensitivity of 153. - Highlights: • A simple, low-cost technique for fabrication of highly sensitive fiber-optic oxygen sensor is described. • ORMOSIL was produced to serve as a matrix for the fabrication of oxygen sensing film. • The fiber-optic oxygen sensor has sensitivity of I N2 /I 100O2 =153. • The stable and reproducible signals were obtained with the fiber-optic oxygen sensor
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Su, Liqiu; Shen, Yanbing; Gao, Tian; Luo, Jianmei; Wang, Min
2017-08-01
In steroid biotransformation, soybean oil can improve the productivity of steroids by increasing substrate solubility and strengthen the cell membrane permeability. However, little is known of its role as oxygen carrier and its mechanism of promoting the steroid biotransformation. In this work, soybean oil used as oxygen vector for the enhancement of androst-4-ene-3,17-dione (AD) production by Mycobacterium neoaurum TCCC 11979 (MNR) was investigated. Upon the addition of 16% (v/v) soybean oil, the volumetric oxygen transfer coefficient (K L a) value increased by 44%, and the peak molar yield of AD (55.76%) was achieved. Analysis of intracellular cofactor levels showed high NAD + , ATP level, and a low NADH/NAD + ratio. Meanwhile, the two key enzymes of the tricarboxylic acid (TCA) cycle, namely, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase, were upregulated after incubation with soybean oil. These enhancements induced by the increasing of oxygen supply showed positive effects on phytosterol (PS) bioconversion. Results could contribute to the understanding of effects of soybean oil as oxygen vector on steroid biotransformation and provided a convenient method for enhancing the efficiency of aerobic steroid biocatalysis.
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High-oxygen and high-carbon dioxide containing atmospheres inhibit growth of food associated moulds
Hoogerwerf, S.W.; Kets, E.P.W.; Dijksterhuis, J.
2002-01-01
Aims: The objective of this study was to determine the relationship between the growth of three foodborne fungi and high-oxygen modified atmosphere. Methods and Results: Petri dishes were incubated in a series of connected flasks, which were placed in a climatized room and flushed continuously with
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Kim, Mikael; Brodersen, Kasper Elgetti; Szabó, Milán; Larkum, Anthony W D; Raven, John A; Ralph, Peter J; Pernice, Mathieu
2018-05-01
Seagrasses are a diverse group of angiosperms that evolved to live in shallow coastal waters, an environment regularly subjected to changes in oxygen, carbon dioxide and irradiance. Zostera muelleri is the dominant species in south-eastern Australia, and is critical for healthy coastal ecosystems. Despite its ecological importance, little is known about the pathways of carbon fixation in Z. muelleri and their regulation in response to environmental changes. In this study, the response of Z. muelleri exposed to control and very low oxygen conditions was investigated by using (i) oxygen microsensors combined with a custom-made flow chamber to measure changes in photosynthesis and respiration, and (ii) reverse transcription quantitative real-time PCR to measure changes in expression levels of key genes involved in C 4 metabolism. We found that very low levels of oxygen (i) altered the photophysiology of Z. muelleri, a characteristic of C 3 mechanism of carbon assimilation, and (ii) decreased the expression levels of phosphoenolpyruvate carboxylase and carbonic anhydrase. These molecular-physiological results suggest that regulation of the photophysiology of Z. muelleri might involve a close integration between the C 3 and C 4 , or other CO 2 concentrating mechanisms metabolic pathways. Overall, this study highlights that the photophysiological response of Z. muelleri to changing oxygen in water is capable of rapid acclimation and the dynamic modulation of pathways should be considered when assessing seagrass primary production.
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Oxygen effect and intracellular oxygen content (adaptation hypothesis)
Energy Technology Data Exchange (ETDEWEB)
Yarmonenko, S P; Ehpshtejn, I M [Akademiya Meditsinskikh Nauk SSSR, Moscow. Onkologicheskij Tsentr
1977-01-01
Experimental data indicating that a radiomodifying action of hypoxia is dependent on the ''prehistory'' of the irradiated object are considered. This dependence manifests itself in a decreased protective action of acute hypoxia on the hypoxia-adapted objects. To explain this a hypothesis is proposed connecting a degree of cell radiosensitivity modification, determined by the oxygen effect, with the intracellular oxygen content. The latter, in accord with current ideas, is regulated by variations in the diffusion resistance to oxygen shown by the cytoplasmic membranes depending on the energy level of the cell and the degree of its oxygenation.
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Oxygen effect and intracellular oxygen content (adaptation hypothesis)
International Nuclear Information System (INIS)
Yarmonenko, S.P.; Ehpshtejn, I.M.
1977-01-01
Experimental data indicating that a radiomodifying action of hypoxia is dependent on the ''prehistory'' of the irradiated object are considered. This dependence manifests itself in a decreased protective action of acute hypoxia on the hypoxia-adapted objects. To explain this a hypothesis is proposed connecting a degree of cell radiosensitivity modification, determined by the oxygen effect, with the intracellular oxygen content. The latter, in accord with current ideas, is regulated by variations in the diffusion resistance to oxygen shown by the cytoplasmic membranes depending on the energy level of the cell and the degree of its oxygenation
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Gardner, Hope Patterson; Fink, Barbara A; Mitchell, Lynn G; Hill, Richard M
2005-06-01
The human corneal oxygen uptake responses associated with the static (nonblinking) and dynamic (blinking) wear of five rigid gas-permeable materials with high oxygen permeabilities were determined for three different center thicknesses and compared with the responses for the normal open eye and severe hypoxic stress (static wear of polymethylmethacrylate). Corneal oxygen uptake rates were measured with a Clark-type polarographic electrode during two sessions with each of 10 human subjects. Measurements were made on the right eye for the normal open eye (air) and after 5 minutes of static and dynamic wear of polymethylmethacrylate and five rigid gas-permeable contact lens materials: Fluoroperm 92 (paflufocon A, Dk = 92), Fluoroperm 151 (paflufocon D, Dk = 151), 1992 Menicon SF-P (melafocon A, Dk = 102), 1995 Menicon SF-P (melafocon A, Dk = 159), and Menicon Z (tisilfocon A, Dk = 163-250). Lenses were manufactured in three different center thicknesses (0.12, 0.16, and 0.20 mm), with all other parameters remaining constant. Repeated-measures analysis of variance was used and included lens material (five levels), blinking condition (two levels), and lens thickness (three levels) as within-subject effects. Significant differences were found in corneal oxygen responses to lens material (p Dk rigid lens materials studied here, moderate changes in lens thickness or material permeability may result in modest differences in corneal hypoxic relief, whereas blinking results in no significant improvement to corneal oxygenation.
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Directory of Open Access Journals (Sweden)
Hong-Zhuan Song
Full Text Available OBJECTIVE: To investigate the value of high-flow nasal cannula oxygen therapy after extubation in patients with acute respiratory failure. METHODS: A single-center, prospective, randomized, controlled pilot trial was conducted between January 2013 and December 2014. Sixty enrolled patients were randomized immediately after extubation into either a high-flow nasal cannula group (n=30 or an air entrainment mask group (n=30 at a fixed inspired oxygen fraction (40%. The success rate of oxygen therapy, respiratory and hemodynamic parameters and subjective discomfort (using a visual analogue scale were assessed at 24h after extubation. RESULTS: The two groups were comparable at extubation. A total of 46 patients were successfully treated including 27 patients in the high-flow nasal cannula group and 19 patients in the air entrainment mask group. Compared to the air entrainment mask group, the success rate of oxygen therapy and the partial pressure of arterial oxygen were significantly higher and the respiratory rate was lower in the high-flow nasal cannula group. In addition, less discomfort related to interface displacement and airway dryness was observed in the high-flow nasal cannula group than in the air entrainment mask group. CONCLUSIONS: At a fixed inspired oxygen fraction, the application of a high-flow nasal cannula after extubation achieves a higher success rate of oxygen therapy and less discomfort at 24h than an air entrainment mask in patients with acute respiratory failure.
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Investigation on the improved radiation hardness of silicon detectors with high oxygen concentration
Moll, Michael; Lindström, G
2000-01-01
We present an investigation on the influence of the oxygen concentration on radiation-induced changes in the effective doping concentration of silicon detectors. Diodes fabricated from silicon with interstitial oxygen content ranging from below 2*10/sup 14/ to 9*10/sup 17/ cm/sup -3/ have been irradiated with fast neutrons up to a fluence of 2*10/sup 15/ cm/sup -2/. Our main interest focused on the so-called stable damage component in the change of the effective doping concentration being of prime importance for the application of silicon detectors in high-energy physics experiments. We demonstrate, that with a high oxygen enrichment the donor removal is appreciably reduced, reaching a value of only 10601130f the initial doping concentration for [O/sub i/]=9*10/sup 17/ cm/sup -3/, while for normal detector grade material with [O/sub i/] below 5*10/sup 16/ cm /sup -3/ that value is 60-90Furthermore, we show that the fluence proportional introduction of stable acceptors is independent of the oxygen concentratio...
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High Pressure and High Temperature State of Oxygen Enriched Ice
LI, M.; Zhang, S.; Jeanloz, R.; Militzer, B.
2016-12-01
Interior models for Uranus and Neptune include a hydrogen/helium/water outer envelope and a core of rock and metal at the center, with superionic water-rich ice proposed as comprising an intermediate layer. Here we consider an oxygen-enriched ice, such as H2O2 hydrogen peroxide (± water), that could form through chemical reaction between water-rich and underlying rocky (i.e., oxygen-rich) layers. As oxygen and its compounds (e.g., H2O, SiO2) form metallic fluids at pressures above 100-150 GPa, the problem amounts to considering oxygen alloying of semiconducting or metallic water. The density of H2O2 is 1.45 g/cc at ambient pressure and 0° C, increasing to 1.71 g/cc in the solid state at about -20° C. There are no Hugoniot data beyond 30 GPa, so we estimated Hugoniots for H2O2 with different initial densities, using both a mixing model based on Hugoniot data for H2O2 and 1/2 O2 (molar volume summation under pressure) and ab initio calculations for unreacted H2O2. The results agree with each other to pressures of about 200 GPa, and the ab initio calculations show evidence of a superionic state at temperatures as low as 500 K, much lower than for water ice. Hydrogen peroxide is expected to be liquid along planetary isentropes for Uranus and Neptune, suggesting that H2O2 may not be present as a pure compound in these planets. Instead, oxygen-enriched H2O ice may be the relevant form of water and oxygen, and might be produced in the laboratory by way of dynamic compression of H2O2 or laser-heating of statically compressed H2O + O2 and/or H2O2.
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International Nuclear Information System (INIS)
Griffiths, L.; Stratford, I.J.
1998-01-01
Purpose: Investigation of the effect of platelet-derived endothelial cell growth factor/thymidine phosphorylase (PD-ECGF/TP) on various aspects of tumour growth in a xenograft model, including growth rate, tumourigenicity and oxygenation levels. Methods and Materials: MDA 231 breast cancer cells overexpressing PD-ECGF/TP protein were made by retroviral transduction. These cells were grown in vitro and in vivo as xenografts. Direct measurement of tumours was used to record growth parameters, while the comet assay with the bioreductive drug RSU 1069 was used to assess tumour cell oxygenation. Results: We report that MDA 231 breast tumour cell lines expressing an increased range of levels of PD-ECGF/TP have increased tumourigenicity positively related to the level of PD-ECGF/TP when implanted in nude mice. As previously reported, tumours grown from these overexpressing cell lines grew faster than the parental line. These tumours expressed higher levels of TP activity and showed increased immunocytochemical staining for PD-ECGF. In addition, the rate of growth was found to be positively related to the level of PD-ECGF/TP expressed by the tumour cells. When the comet assay was used to compare the oxygenation status of cells between the parental and PD-ECGF/TP overexpressing tumours, the latter were found to have a larger proportion of well oxygenated cells. This is consistent with these tumours having an increased and functionally competent vascular supply in response to the expression of PD-ECGF/TP. Conclusion: PD-ECGF/TP appears to be capable of influencing tumourigenicity, angiogenesis and tumour growth in a proportional manner and can directly influence tumour oxygenation levels via its role in formation of functional vasculature
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Ding, Jiule; Xing, Wei; Wu, Dongmei; Chen, Jie; Pan, Liang; Sun, Jun; Xing, Shijun; Dai, Yongming
2015-01-01
To assess the feasibility of susceptibility-weighted imaging (SWI) while monitoring changes in renal oxygenation level after water loading. Thirty-two volunteers (age, 28.0 ± 2.2 years) were enrolled in this study. SWI and multi-echo gradient echo sequence-based T2(*) mapping were used to cover the kidney before and after water loading. Cortical and medullary parameters were measured using small regions of interest, and their relative changes due to water loading were calculated based on baseline and post-water loading data. An intraclass correlation coefficient analysis was used to assess inter-observer reliability of each parameter. A receiver operating characteristic curve analysis was conducted to compare the performance of the two methods for detecting renal oxygenation changes due to water loading. Both medullary phase and medullary T2(*) values increased after water loading (p T2(*) changes (p > 0.05). Interobserver reliability was excellent for the T2(*) values, good for SWI cortical phase values, and moderate for the SWI medullary phase values. The area under receiver operating characteristic curve of the SWI medullary phase values was 0.85 and was not different from the medullary T2(*) value (0.84). Susceptibility-weighted imaging enabled monitoring changes in the oxygenation level in the medulla after water loading, and may allow comparable feasibility to detect renal oxygenation level changes due to water loading compared with that of T2(*) mapping.
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Zolpidem reduces the blood oxygen level-dependent signal during visual system stimulation
Licata, Stephanie C.; Lowen, Steven B.; Trksak, George H.; MacLean, Robert R.; Lukas, Scott E.
2011-01-01
Zolpidem is a short-acting imidazopyridine hypnotic that binds at the benzodiazepine binding site on specific GABAA receptors to enhance fast inhibitory neurotransmission. The behavioral and receptor pharmacology of zolpidem has been studied extensively, but little is known about its neuronal substrates in vivo. In the present within-subject, double-blind, and placebo-controlled study, blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) at 3 Tesla was used to assess...
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Comparison of the effect of neutron irradiation on high purity vanadium and vanadium oxygen alloys
International Nuclear Information System (INIS)
Arsenault, R.J.; Bressers, J.
1977-01-01
An investigation of the effect of neutron damage on the low temperature deformation characteristics of high purity vanadium (R/sub 300K//R/sub 4.2K/ = 1100) was undertaken for two purposes. One purpose was to determine if reducing the purity interstitial content to a lower level would result in a large difference in the effective stress between irradiated and non-irradiated samples. The present data along with previously obtained data does indicate that the difference increases as the impurity interstitial content is reduced. The explanation of this observation is based on the rapid increase of the non-irradiated yield stress at 77 0 K due to small increases in the oxygen content; however, the increase of the yield stress of the irradiated samples is much less with the same increase in oxygen content. A second purpose of this investigation was to determine the size and density of observable neutron produced defects as a function of oxygen content by transmission electron microscopy, and to relate the changes in density with changes in the yield stress. It was found that the density decreases and the size increases as the oxygen content decreases. There is qualitative agreement between the increase in yield stress at 300 0 K and the observable defect density. However, the change in the yield stress at 77 0 K due to neutron irradiation cannot be related to defect density and size
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High temperature, oxygen, and performance: Insights from reptiles and amphibians.
Gangloff, Eric J; Telemeco, Rory S
2018-04-25
Much recent theoretical and empirical work has sought to describe the physiological mechanisms underlying thermal tolerance in animals. Leading hypotheses can be broadly divided into two categories that primarily differ in organizational scale: 1) high temperature directly reduces the function of subcellular machinery, such as enzymes and cell membranes, or 2) high temperature disrupts system-level interactions, such as mismatches in the supply and demand of oxygen, prior to having any direct negative effect on the subcellular machinery. Nonetheless, a general framework describing the contexts under which either subcellular component or organ system failure limits organisms at high temperatures remains elusive. With this commentary, we leverage decades of research on the physiology of ectothermic tetrapods (amphibians and non-avian reptiles) to address these hypotheses. Available data suggest both mechanisms are important. Thus, we expand previous work and propose the Hierarchical Mechanisms of Thermal Limitation (HMTL) hypothesis, which explains how subcellular and organ system failures interact to limit performance and set tolerance limits at high temperatures. We further integrate this framework with the thermal performance curve paradigm commonly used to predict the effects of thermal environments on performance and fitness. The HMTL framework appears to successfully explain diverse observations in reptiles and amphibians and makes numerous predictions that remain untested. We hope that this framework spurs further research in diverse taxa and facilitates mechanistic forecasts of biological responses to climate change.
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International Nuclear Information System (INIS)
Izak, Pavel; Hrma, Pavel R.; Wilson, Benjamin K.; Vienna, John D.
2000-01-01
The redox state of iron affects spinal crystallization in vitrified high-level waste (HLW) glass. Simulated HLW glass with spinel as the primary crystalline phase field was heat treated at constant temperatures within the interval from 850 C to 1300 C under varying atmospheres with oxygen partial pressure, Po2, ranging from 1x10-16 kPa (pure CO) to 101 kPa (pure O2). Liquidus temperature (TL) of glass increased with decreasing Po2 up to Po2 > 3 x 10-9 kPa. At Po2 < 3 x 10-9 kPa, Ni-Fe alloy precipitated from the glass, and TL decreased. Samples were analyzed with optical microscope and scanning electron microscope. The mass fraction of spinel in glass was determined using quantitative X-ray diffraction. Spinel composition was investigated with energy disperse spectroscopy. Ferrous-ferric equilibrium at TL was calculated in a HLW glass as a function of temperature and Po2, based on the previous studies by Schreiber. TL/FeO over the interval 0.0063 < gFeO < 0.051 (1x10-2 kPa < Po2 < 3x10-9 kPa) was estimated from calculated ferrous-ferric equilibrium at TL as 1835 C
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Single-cell measurement of red blood cell oxygen affinity.
Di Caprio, Giuseppe; Stokes, Chris; Higgins, John M; Schonbrun, Ethan
2015-08-11
Oxygen is transported throughout the body by hemoglobin (Hb) in red blood cells (RBCs). Although the oxygen affinity of blood is well-understood and routinely assessed in patients by pulse oximetry, variability at the single-cell level has not been previously measured. In contrast, single-cell measurements of RBC volume and Hb concentration are taken millions of times per day by clinical hematology analyzers, and they are important factors in determining the health of the hematologic system. To better understand the variability and determinants of oxygen affinity on a cellular level, we have developed a system that quantifies the oxygen saturation, cell volume, and Hb concentration for individual RBCs in high throughput. We find that the variability in single-cell saturation peaks at an oxygen partial pressure of 2.9%, which corresponds to the maximum slope of the oxygen-Hb dissociation curve. In addition, single-cell oxygen affinity is positively correlated with Hb concentration but independent of osmolarity, which suggests variation in the Hb to 2,3-diphosphoglycerate (2-3 DPG) ratio on a cellular level. By quantifying the functional behavior of a cellular population, our system adds a dimension to blood cell analysis and other measurements of single-cell variability.
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Murakami, Takashi; Sreenivas, Bulusu; Sharma, Subrata Das; Sugimori, Hirokazu
2011-07-01
, and short-term fluctuations of both temperature and P during the possible, multiple global-scale glaciations. The calculations indicate that P increased gradually, linearly on the logarithmic scale, from ˜10 -3 atm between 2.5 and 2.0 Ga. Our calculations show that the P levels would have fluctuated significantly, if intense, global glaciation(s) followed by period(s) of high temperature occurred during the Paleoproterozoic. This gradual rise model proposes a distinct, quantitative pattern for the first atmospheric oxygen rise with important implications for the evolution of life.
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DEFF Research Database (Denmark)
Stefánsson, Einar; Pedersen, Daniella Bach; Jensen, Peter Koch
2005-01-01
The oxygen tension of the optic nerve is regulated by the intraocular pressure and systemic blood pressure, the resistance in the blood vessels and oxygen consumption of the tissue. The oxygen tension is autoregulated and moderate changes in intraocular pressure or blood pressure do not affect...... the optic nerve oxygen tension. If the intraocular pressure is increased above 40 mmHg or the ocular perfusion pressure decreased below 50 mmHg the autoregulation is overwhelmed and the optic nerve becomes hypoxic. A disturbance in oxidative metabolism in the cytochromes of the optic nerve can be seen...... at similar levels of perfusion pressure. The levels of perfusion pressure that lead to optic nerve hypoxia in the laboratory correspond remarkably well to the levels that increase the risk of glaucomatous optic nerve atrophy in human glaucoma patients. The risk for progressive optic nerve atrophy in human...
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Celina Selvakumari, J.; Dhanalakshmi, J.; Pathinettam Padiyan, D.
2016-10-01
The intention of this work is to reduce the oxygen level in graphene oxide. The reduction process was initiated while preparing graphene oxide using modified Hummer’s method. In this new method, increase in hydrogen peroxide concentration during the preparation process results in the oxygen content reduction. Adding green tea (camellia sinensis) extract with increased hydrogen peroxide results in further reduction of oxygen content and changed the graphene oxide to reduced graphene oxide. The structural and optical properties of the new found reduced graphene oxide was analysed using XRD, FTIR, TEM, Raman and UV-vis spectra. The overall observation reflects that the sp3 carbon network of graphene oxide changed into sp2 carbon lattice of graphene which is very handful in supercapacitor and biosensor fields.
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Wong, Jaclyn W M; Kong, Amy H S; Lam, Sau Yee; Woo, Peter Y M
2017-12-15
Patients with obstructive sleep apnea are frequently considered unsuitable candidates for awake craniotomy due to anticipated problems with oxygenation, ventilation, and a potentially difficult airway. At present, only a handful of such accounts exist in the literature. Our report describes the novel use of high-flow nasal oxygen therapy for a patient with moderate obstructive sleep apnea who underwent an awake craniotomy under deep sedation. The intraoperative application of high-flow nasal oxygen therapy achieved satisfactory oxygenation, maintained the partial carbon dioxide pressure within a reasonable range even during periods of deep sedation, permitted responsive patient monitoring during mapping, and provided excellent patient and surgeon satisfaction.
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Silicon Micropore-Based Parallel Plate Membrane Oxygenator.
Dharia, Ajay; Abada, Emily; Feinberg, Benjamin; Yeager, Torin; Moses, Willieford; Park, Jaehyun; Blaha, Charles; Wright, Nathan; Padilla, Benjamin; Roy, Shuvo
2018-02-01
Extracorporeal membrane oxygenation (ECMO) is a life support system that circulates the blood through an oxygenating system to temporarily (days to months) support heart or lung function during cardiopulmonary failure until organ recovery or replacement. Currently, the need for high levels of systemic anticoagulation and the risk for bleeding are main drawbacks of ECMO that can be addressed with a redesigned ECMO system. Our lab has developed an approach using microelectromechanical systems (MEMS) fabrication techniques to create novel gas exchange membranes consisting of a rigid silicon micropore membrane (SμM) support structure bonded to a thin film of gas-permeable polydimethylsiloxane (PDMS). This study details the fabrication process to create silicon membranes with highly uniform micropores that have a high level of pattern fidelity. The oxygen transport across these membranes was tested in a simple water-based bench-top set-up as well in a porcine in vivo model. It was determined that the mass transfer coefficient for the system using SµM-PDMS membranes was 3.03 ± 0.42 mL O 2 min -1 m -2 cm Hg -1 with pure water and 1.71 ± 1.03 mL O 2 min -1 m -2 cm Hg -1 with blood. An analytic model to predict gas transport was developed using data from the bench-top experiments and validated with in vivo testing. This was a proof of concept study showing adequate oxygen transport across a parallel plate SµM-PDMS membrane when used as a membrane oxygenator. This work establishes the tools and the equipoise to develop future generations of silicon micropore membrane oxygenators. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
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A highly accurate method for determination of dissolved oxygen: Gravimetric Winkler method
International Nuclear Information System (INIS)
Helm, Irja; Jalukse, Lauri; Leito, Ivo
2012-01-01
Highlights: ► Probably the most accurate method available for dissolved oxygen concentration measurement was developed. ► Careful analysis of uncertainty sources was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. ► This development enables more accurate calibration of dissolved oxygen sensors for routine analysis than has been possible before. - Abstract: A high-accuracy Winkler titration method has been developed for determination of dissolved oxygen concentration. Careful analysis of uncertainty sources relevant to the Winkler method was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. The most important improvements were: gravimetric measurement of all solutions, pre-titration to minimize the effect of iodine volatilization, accurate amperometric end point detection and careful accounting for dissolved oxygen in the reagents. As a result, the developed method is possibly the most accurate method of determination of dissolved oxygen available. Depending on measurement conditions and on the dissolved oxygen concentration the combined standard uncertainties of the method are in the range of 0.012–0.018 mg dm −3 corresponding to the k = 2 expanded uncertainty in the range of 0.023–0.035 mg dm −3 (0.27–0.38%, relative). This development enables more accurate calibration of electrochemical and optical dissolved oxygen sensors for routine analysis than has been possible before.
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DEFF Research Database (Denmark)
Meyhoff, Christian Sylvest; Jorgensen, Lars N; Wetterslev, Jørn
2012-01-01
A high perioperative inspiratory oxygen fraction (80%) has been recommended to prevent postoperative wound infections. However, the most recent and one of the largest trials, the PROXI trial, found no reduction in surgical site infection, and 30-day mortality was higher in patients given 80% oxygen...
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Alexsandra da Silva Neto Trajano, Larissa; da Silva, Camila Luna; de Carvalho, Simone Nunes; Cortez, Erika; Mencalha, André Luiz; de Souza da Fonseca, Adenilson; Stumbo, Ana Carolina
2016-07-01
Low-level infrared laser is considered safe and effective for treatment of muscle injuries. However, the mechanism involved on beneficial effects of laser therapy are not understood. The aim was to evaluate cell viability, reactive oxygen species, apoptosis, and necrosis in myoblast cultures exposed to low-level infrared laser at therapeutic fluences. C2C12 myoblast cultures at different (2 and 10 %) fetal bovine serum (FBS) concentrations were exposed to low-level infrared laser (808 nm, 100 mW) at different fluences (10, 35, and 70 J/cm(2)) and evaluated after 24, 48, and 72 h. Cell viability was evaluated by WST-1 assay; reactive oxygen species (ROS), apoptosis, and necrosis were evaluated by flow cytometry. Cell viability was decreased atthe lowest FBS concentration. Laser exposure increased the cell viability in myoblast cultures at 2 % FBS after 48 and 72 h, but no significant increase in ROS was observed. Apoptosis was decreased at the higher fluence and necrosis was increased at lower fluence in myoblast cultures after 24 h of laser exposure at 2 % FBS. No laser-induced alterations were obtained at 10 % FBS. Results show that level of reactive oxygen species is not altered, at least to those evaluated in this study, but low-level infrared laser exposure affects cell viability, apoptosis, and necrosis in myoblast cultures depending on laser fluence and physiologic conditions of cells.
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Directory of Open Access Journals (Sweden)
Bonnie Solmes
2000-01-01
Full Text Available LTOT is prescribed for people with chronic lung disease in whom there is a decrease in the ability of the lungs to supply enough oxygen to the body. The heart is obliged to pump faster to meet the body's oxygen requirements. This may place undue stress on the heart, resulting in palpitations, dizziness and fatigue. A low oxygen level in arterial blood is also harmful to the heart, the brain and the pulmonary blood vessels. Oxygen therapy is used to break this cycle. A person with low blood oxygen will often be able to accomplish more with less fatigue with the help of supplemental oxygen therapy. Shortness of breath is a mechanical problem resulting from the effects of chronic obstructive pulmonary disease. Oxygen therapy may or may not reduce shortness of breath, but it will help the lungs and heart to function with less stress.
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Directory of Open Access Journals (Sweden)
Michael eEderer
2014-03-01
Full Text Available The efficient redesign of bacteria for biotechnological purposes, such as biofuel production, waste disposal or specific biocatalytic functions, requires a quantitative systems-level understanding of energy supply, carbon and redox metabolism. The measurement of transcript levels, metabolite concentrations and metabolic fluxes per se gives an incomplete picture. An appreciation of the interdependencies between the different measurement values is essential for systems-level understanding. Mathematical modeling has the potential to provide a coherent and quantitative description of the interplay between gene expression, metabolite concentrations and metabolic fluxes. Escherichia coli undergoes major adaptations in central metabolism when the availability of oxygen changes. Thus, an integrated description of the oxygen response provides a benchmark of our understanding of carbon, energy and redox metabolism. We present the first comprehensive model of the central metabolism of E. coli that describes steady-state metabolism at different levels of oxygen availability. Variables of the model are metabolite concentrations, gene expression levels, transcription factor activities, metabolic fluxes and biomass concentration. We analyze the model with respect to the production capabilities of central metabolism of E. coli. In particular, we predict how precursor and biomass concentration are affected by product formation.
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A DLTS study of the evolution of oxygen precipitates in Si at high temperature and high pressure
International Nuclear Information System (INIS)
Antonova, I.V.; Popov, V.P.; Fedina, L.I.; Shaimeev, S.S.; Misiuk, A.
1996-01-01
The effect of high hydrostatic pressure on the dissolution of oxygen precipitates introduced beforehand into Si at temperatures of 920-1000 K (over period of 96 h) is investigated by the DLTS method. A measurement procedure, based on the formation of electrically active complexes (interstitial oxygen atom-vacancy) during electron irradiation of the samples, is proposed. It is shown that the precipitates do not decompose when point defects are introduced at room temperature. As the treatment temperature increases (to 1220-1650 K), for the same values of the hydrostatic pressure (up to 1.3 GPa) the intensity of the decomposition of oxygen precipitates increases and at 1650 K they are completely dissolved. Study of the decomposition kinetics showed that hydrostatic pressure raises the limit of solubility of the oxygen atoms Oi and slows down their diffusion. It is determined that the diffusion activation energy Ea, just as the preexponential factor D0, in the expression for the diffusion decrease with increasing hydrostatic pressure, resulting in a lower diffusion. Possible mechanisms for the effect of hydrostatic pressure on oxygen diffusion near a precipitate are discussed
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Zhou, Bao-Chun; Liu, Li-Jun; Liu, Bing
2016-09-01
Although hyperbaric oxygen (HBO) therapy can promote the recovery of neural function in patients who have suffered traumatic brain injury (TBI), the underlying mechanism is unclear. We hypothesized that hyperbaric oxygen treatment plays a neuroprotective role in TBI by increasing regional transcranial oxygen saturation (rSO 2 ) and oxygen partial pressure (PaO 2 ). To test this idea, we compared two groups: a control group with 20 healthy people and a treatment group with 40 TBI patients. The 40 patients were given 100% oxygen of HBO for 90 minutes. Changes in rSO 2 were measured. The controls were also examined for rSO 2 and PaO 2 , but received no treatment. rSO 2 levels in the patients did not differ significantly after treatment, but levels before and after treatment were significantly lower than those in the control group. PaO 2 levels were significantly decreased after the 30-minute HBO treatment. Our findings suggest that there is a disorder of oxygen metabolism in patients with sub-acute TBI. HBO does not immediately affect cerebral oxygen metabolism, and the underlying mechanism still needs to be studied in depth.
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Radiation hardening of oxygen-doped niobium by 14-MeV neutrons
International Nuclear Information System (INIS)
Bradley, E.R.; Jones, R.H.
1983-09-01
The flow properties of niobium containing 185 and 480 wt ppM oxygen have been studied following irradiation at 300K with T(d,n) neutrons to fluence levels ranging from 6 x 10 20 to 2 x 10 22 m -2 . Two hardening stages connected by a plateau region were observed in the niobium containing 185 wt ppM oxygen. Increasing the oxygen content by 300 wt ppM oxygen shifted the beginning of the high-fluence hardening stage from 6 x 10 21 to 1 x 10 21 m -2 , thereby eliminating the plateau region. This shift resulted in 1.5 times more hardening in the oxygen-doped niobium irradiated to fluence levels above 5 x 10 21 m -2
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Growth enhancement and gene expression of Arabidopsis thaliana irradiated with active oxygen species
Watanabe, Satoshi; Ono, Reoto; Hayashi, Nobuya; Shiratani, Masaharu; Tashiro, Kosuke; Kuhara, Satoru; Inoue, Asami; Yasuda, Kaori; Hagiwara, Hiroko
2016-07-01
The characteristics of plant growth enhancement effect and the mechanism of the enhancement induced by plasma irradiation are investigated using various active species in plasma. Active oxygen species in oxygen plasma are effective for growth enhancement of plants. DNA microarray analysis of Arabidopsis thaliana indicates that the genes coding proteins that counter oxidative stresses by eliminating active oxygen species are expressed at significantly high levels. The size of plant cells increases owing to oxygen plasma irradiation. The increases in gene expression levels and cell size suggest that the increase in the expression level of the expansin protein is essential for plant growth enhancement phenomena.
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Bibby, Susan R S; Jones, Deborah A; Ripley, Ruth M; Urban, Jill P G
2005-03-01
In vitro measurements of metabolic rates of isolated bovine nucleus pulposus cells at varying levels of oxygen, glucose, and pH. To obtain quantitative information on the interactions between oxygen and glucose concentrations and pH, and the rates of oxygen and glucose consumption and lactic acid production, for disc nucleus cells. Disc cells depend on diffusion from blood vessels at the disc margins for supply of nutrients. Loss of supply is thought to lead to disc degeneration, but how loss of supply affects nutrient concentrations in the disc is not known; nutrient concentrations within discs can normally only be calculated, because concentration measurements are invasive. However, realistic predictions cannot be made until there are data from measurements of metabolic rates at conditions found in the disc in vivo, i.e., at low levels of oxygen, glucose, and pH. A metabolism chamber was designed to allow simultaneous recording of oxygen and glucose concentrations and of pH. These concentrations were measured electrochemically with custom-built glucose and oxygen sensors; lactic acid was measured biochemically. Bovine nucleus pulposus cells were isolated and inserted into the chamber, and simultaneous rates of oxygen and glucose consumption and of lactic acid production were measured over a range of glucose, oxygen, and pH levels. There were strong interactions between rates of metabolism and oxygen consumption and pH. At atmospheric oxygen levels, oxygen consumption rate at pH 6.2 was 32% of that at pH 7.4. The rate fell by 60% as oxygen concentration was decreased from 21 to 5% at pH 7.4, but only by 20% at pH 6.2. Similar interactions were seen for lactic acid production and glucose consumption rates; we found that glycolysis rates fell at low oxygen and glucose concentrations and low pH. Equations were derived that satisfactorily predict the effect of nutrient and metabolite concentrations on rates of lactic acid production rate and oxygen consumption. Disc
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Oxygen and animal evolution: Did a rise of atmospheric oxygen trigger the origin of animals?
DEFF Research Database (Denmark)
Mills, Daniel Brady; Canfield, Donald Eugene
2014-01-01
Recent studies challenge the classical view that the origin of animal life was primarily controlled by atmospheric oxygen levels. For example, some modern sponges, representing early-branching animals, can live under 200 times less oxygen than currently present in the atmosphere - levels commonly...... thought to have been maintained prior to their origination. Furthermore, it is increasingly argued that the earliest animals, which likely lived in low oxygen environments, played an active role in constructing the well-oxygenated conditions typical of the modern oceans. Therefore, while oxygen is still...
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The Not-So-Global Blood Oxygen Level-Dependent Signal.
Billings, Jacob; Keilholz, Shella
2018-04-01
Global signal regression is a controversial processing step for resting-state functional magnetic resonance imaging, partly because the source of the global blood oxygen level-dependent (BOLD) signal remains unclear. On the one hand, nuisance factors such as motion can readily introduce coherent BOLD changes across the whole brain. On the other hand, the global signal has been linked to neural activity and vigilance levels, suggesting that it contains important neurophysiological information and should not be discarded. Any widespread pattern of coordinated activity is likely to contribute appreciably to the global signal. Such patterns may include large-scale quasiperiodic spatiotemporal patterns, known also to be tied to performance on vigilance tasks. This uncertainty surrounding the separability of the global BOLD signal from concurrent neurological processes motivated an examination of the global BOLD signal's spatial distribution. The results clarify that although the global signal collects information from all tissue classes, a diverse subset of the BOLD signal's independent components contribute the most to the global signal. Further, the timing of each network's contribution to the global signal is not consistent across volunteers, confirming the independence of a constituent process that comprises the global signal.
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Yeast alter micro-oxygenation of wine: oxygen consumption and aldehyde production.
Han, Guomin; Webb, Michael R; Richter, Chandra; Parsons, Jessica; Waterhouse, Andrew L
2017-08-01
Micro-oxygenation (MOx) is a common winemaking treatment used to improve red wine color development and diminish vegetal aroma, amongst other effects. It is commonly applied to wine immediately after yeast fermentation (phase 1) or later, during aging (phase 2). Although most winemakers avoid MOx during malolactic (ML) fermentation, it is often not possible to avoid because ML bacteria are often present during phase 1 MOx treatment. We investigated the effect of common yeast and bacteria on the outcome of micro-oxygenation. Compared to sterile filtered wine, Saccharomyces cerevisiae inoculation significantly increased oxygen consumption, keeping dissolved oxygen in wine below 30 µg L -1 during micro-oxygenation, whereas Oenococcus oeni inoculation was not associated with a significant impact on the concentration of dissolved oxygen. The unfiltered baseline wine also had both present, although with much higher populations of bacteria and consumed oxygen. The yeast-treated wine yielded much higher levels of acetaldehyde, rising from 4.3 to 29 mg L -1 during micro-oxygenation, whereas no significant difference was found between the bacteria-treated wine and the filtered control. The unfiltered wine exhibited rapid oxygen consumption but no additional acetaldehyde, as well as reduced pyruvate. Analysis of the acetaldehyde-glycerol acetal levels showed a good correlation with acetaldehyde concentrations. The production of acetaldehyde is a key outcome of MOx and it is dramatically increased in the presence of yeast, although it is possibly counteracted by the metabolism of O. oeni bacteria. Additional controlled experiments are necessary to clarify the interaction of yeast and bacteria during MOx treatments. Analysis of the glycerol acetals may be useful as a proxy for acetaldehyde levels. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.
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High temperature thermodynamics of solutions of oxygen in vanadium, niobium and tantalum
International Nuclear Information System (INIS)
Boureau, G.; Gerdanian, P.
1981-01-01
The Tian-Calvet microcalorimetric method has been applied to the determination at 1323 K of ΔH(O 2 ), the partial molar enthalpy of mixing of oxygen in vanadium, niobium and tantalum. The present results are in good agreement with earlier studies using e.m.f. techniques. Nevertheless in the first two solutions, ΔH(O 2 ) has been found somewhat more negative than previously reported. The partial molar entropies of mixing have been recalculated. The low values of the excess entropies are explained by a strong increase of the Debye temperature and a decrease of the electronic density of states at the Fermi level as the oxygen content increases. (author)
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Baker, J L; Derr, A M; Karuppaiah, K; MacGilvray, M E; Kajfasz, J K; Faustoferri, R C; Rivera-Ramos, I; Bitoun, J P; Lemos, J A; Wen, Z T; Quivey, R G
2014-06-01
NADH oxidase (Nox, encoded by nox) is a flavin-containing enzyme used by the oral pathogen Streptococcus mutans to reduce diatomic oxygen to water while oxidizing NADH to NAD(+). The critical nature of Nox is 2-fold: it serves to regenerate NAD(+), a carbon cycle metabolite, and to reduce intracellular oxygen, preventing formation of destructive reactive oxygen species (ROS). As oxygen and NAD(+) have been shown to modulate the activity of the global transcription factors Spx and Rex, respectively, Nox is potentially poised at a critical junction of two stress regulons. In this study, microarray data showed that either addition of oxygen or loss of nox resulted in altered expression of genes involved in energy metabolism and transport and the upregulation of genes encoding ROS-metabolizing enzymes. Loss of nox also resulted in upregulation of several genes encoding transcription factors and signaling molecules, including the redox-sensing regulator gene rex. Characterization of the nox promoter revealed that nox was regulated by oxygen, through SpxA, and by Rex. These data suggest a regulatory loop in which the roles of nox in reduction of oxygen and regeneration of NAD(+) affect the activity levels of Spx and Rex, respectively, and their regulons, which control several genes, including nox, crucial to growth of S. mutans under conditions of oxidative stress. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
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Effects of acetazolamide on cerebral blood flow and brain tissue oxygenation
DEFF Research Database (Denmark)
Lassen, N A; Friberg, L; Kastrup, J
1987-01-01
Oral administration of 1 g of acetazolamide to 8 normal subjects studied at sea level and in normoxia caused an acute increase in cerebral blood flow (CBF). During the subsequent prolonged oral treatment with 1 g of acetazolamide daily, CBF returned to normal within 2 days. The alveolar CO2 tension...... decreased gradually to 70% of the control value, indicating hyperventilation. At sea level hyperventilation will not increase brain oxygenation significantly in normal man, as the arterial oxygen content only increases minimally, while CBF is unchanged. At high altitude the beneficial effects...... of acetazolamide on the symptoms of acute mountain sickness may well be due to an improved oxygen supply to the brain, as hyperventilation will, at the low ambient PO2, cause a significant increase of the arterial oxygen content, while CBF presumably is unaffected by the drug. During hypoxia at high altitude...
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Oxygen diffusion in high-Tc superconductors
International Nuclear Information System (INIS)
Rothman, S.J.; Routbort, J.L.
1992-07-01
The cuprate superconductors are fascinating not only because of their technical promise, but also because of their structures, especially the anisotropy of the crystal lattice. There are some structural similarities among these compounds, but also significant differences. Measurements of the oxygen tracer diffusion coefficients have been carried out as a function of temperature, oxygen partial pressure, crystal orientation, and doping in the La-Sr-Cu-0, Y-Ba-Cu-0, and Bi-Sr-Ca-Cu-0 systems. These measurements have revealed a variety of defect mechanisms operating in these compounds; the exact nature of the mechanism depends on the details of the structure
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Mitzi, David Brian
1990-01-01
A directional solidification method for growing large single crystals in the Bi_2Sr _2CaCu_2O _{8+delta} system is reported. Ion substitutions, with replacement of La for Sr and Y for Ca, as well as oxygen doping in these crystals has been explored. Ion doping results in little change of the superconducting transition for substitution levels below 20-25% (as a result of simultaneous oxygen intercalation), while beyond this level, the Meissner signal broadens and the low temperature Meissner signal decreases. Microprobe analysis and x-ray diffraction performed on these more highly substituted single crystals, provides evidence for inhomogeneity and phase segregation into regions of distinct composition. Annealing unsubstituted crystals in increasing partial pressures of oxygen reversibly depresses the superconducting transition temperature from 90K (as made) to 77K (oxygen pressure annealed) while the Hall concentrations increase from n = 3.1(3) times 10 ^{21} cm^{ -3} (0.34 holes/Cu site) to 4.6(3) times 10^{21} cm^{-3} (0.50 holes/Cu site). Further suppression of T_{c} to 72K is possible by annealing in oxygen pressures up to 100atm. No degradation of the Meissner transition or other indications of inhomogeneity or phase segregation with doping are noted, suggesting that oxygen doped Bi_2Sr _2CaCu_2O _{8+delta} is a suitable system for pursuing doping studies. The decrease in T _{c} with concentration for 0.34 <=q n <=q 0.50 indicates that a high carrier concentration regime exists where T_{c} decreases with n and suggests that this decrease does not arise from material inhomogeneity or other materials problems. The physical properties of these Bi _2Sr_2CaCu _2O_{8+delta} crystals, in this high carrier concentration regime, will be discussed.
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Hakim, Farzana; Kaitsuka, Taku; Raeed, Jamiruddin Mohd; Wei, Fan-Yan; Shiraki, Nobuaki; Akagi, Tadayuki; Yokota, Takashi; Kume, Shoen; Tomizawa, Kazuhito
2014-04-04
Pluripotent stem cells have potential applications in regenerative medicine for diabetes. Differentiation of stem cells into insulin-producing cells has been achieved using various protocols. However, both the efficiency of the method and potency of differentiated cells are insufficient. Oxygen tension, the partial pressure of oxygen, has been shown to regulate the embryonic development of several organs, including pancreatic β-cells. In this study, we tried to establish an effective method for the differentiation of induced pluripotent stem cells (iPSCs) into insulin-producing cells by culturing under high oxygen (O2) conditions. Treatment with a high O2 condition in the early stage of differentiation increased insulin-positive cells at the terminus of differentiation. We found that a high O2 condition repressed Notch-dependent gene Hes1 expression and increased Ngn3 expression at the stage of pancreatic progenitors. This effect was caused by inhibition of hypoxia-inducible factor-1α protein level. Moreover, a high O2 condition activated Wnt signaling. Optimal stage-specific treatment with a high O2 condition resulted in a significant increase in insulin production in both mouse embryonic stem cells and human iPSCs and yielded populations containing up to 10% C-peptide-positive cells in human iPSCs. These results suggest that culturing in a high O2 condition at a specific stage is useful for the efficient generation of insulin-producing cells.
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High-temperature vaporization behavior of oxygen-deficient thoria
International Nuclear Information System (INIS)
Ackermann, R.J.; Tetenbaum, M.
1979-01-01
The experimental results of the present study on the vaporization behavior of oxygen-deficient thoria are directed toward a more precise and detailed study of the lower phase boundary (l.p.b.) and congruently vaporizing composition (c.v.c), and intermediate compositions, and the corresponding oxygen potentials and total pressure at temperatures above 2000K. The l.p.b. and c.v.c. values were found to fit an equation of the form log x = A + (B/T), where x is the stoichiometric defect in ThO 2 -x. Oxygen potentials corresponding to the l.p.b. and c.v.c. have been estimated from vapor pressures and thermodynamic data. A very sharp decrease in oxygen potential occurs when thoria isreduced only slightly from the stoichiometric composition. In the temperature range from 2400 to 2655 K, the oxygen partial pressure dependency of x in ThO 2 -x was found to be approximately proportional to PO 2 - 1 /4to PO 2 - 1 /. The small extent of reduction over a wide range of oxygen potentials at these temperatures is a clear illustration of the higher stability of the ThO 2 -x phase compared with that of UO 2 -x. Values of ΔHO 2 and ΔSO 2 have been estimated for selected compositions from the dependence of the measured oxygen potential on temperature. Estimates of the standard free energy of formation of bivariant ThO 2 -x compositions have been made. A substantial increase in the total pressure of thorium-bearing species occurs when stoichiometric thoria is reduced toward the lower phase boundary. (orig.) [de
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Directory of Open Access Journals (Sweden)
Sanjay Singhal
2017-01-01
Full Text Available Objectives: To evaluate the safety and efficacy of treating high-altitude pulmonary edema (HAPE by bed rest and supplemental oxygen in hospital setting at high altitude. Materials and Methods: In a prospective case series, all patients who were diagnosed clinically with HAPE on admission to our hospital located at a height of 11,500 ft were evaluated and managed with bed rest and oxygen supplementation. Results: A total of 43 patients of HAPE with mean age of 31 years (range 20–48 years were admitted to our hospital. Infections followed by unaccustomed physical exertion were the predominant risk factors. 95.35% of the patients improved successfully with oxygen and bed rest alone with mean hospital stay of 2.67 ± 1.06 (1–6 days. Two patients (4.65% required nifedipine and evacuation to lower altitude. Of this, one patient suffering from concomitant viral infection expired 4 days after evacuation to near sea level. Conclusion: Majority of the patients with HAPE where medical facilities are available can be safely treated with bed rest and oxygen supplementation at moderate high altitude without descent.
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DEFF Research Database (Denmark)
Bolic, Andrijana; Larsson, Hilde Kristina; Hugelier, Siewert
2016-01-01
solution and replacement for existing microtiter plates, shaken flasks and bench scale bioreactors. In this work, a new design of a milliliter-scale bioreactor system is presented and characterized. The entire system consists of a platform with gas connections, heater, temperature sensor and optical fibers...... on the one side and a bioreactor with special designed magnetic stirrer and non-invasive optical sensors for measurement of pH, dissolved oxygen and optical density on the other side. The system has a high level of flexibility in terms of volume (0.5–2 mL), aeration (sparging and surface aeration) and mixing...
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High-resolution spectra of stars in globular clusters. VI - Oxygen-deficient red giant stars in M13
International Nuclear Information System (INIS)
Brown, J.A.; Wallerstein, G.; Oke, J.B.
1991-01-01
From high-resolution, high signal-to-noise spectra, abundances of carbon, nitrogen, and oxygen and the C-12/C-13 ratio for five red giants in M13, including star II-67, which has previously been reported to be deficient in oxygen have been determined. Three of the five stars exhibit substantial oxygen deficiencies; O/Fe values range from +0.5 to less than about 0.3. The sum of the CNO nuclides is the same for all stars, which is interpreted as evidence that mixing of CNO-cycled material into the envelope is the cause of the variations in oxygen abundance. 41 refs
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Evaluation of hydrogen and oxygen impurity levels on silicon surfaces
Energy Technology Data Exchange (ETDEWEB)
Kenny, M.J.; Wielunski, L.S.; Netterfield, R.P.; Martin, P.J.; Leistner, A. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics
1996-12-31
This paper reports on surface analytical techniques used to quantify surface concentrations of impurities such as oxygen and hydrogen. The following analytical techniques were used: Rutherford and Backscattering, elastic recoil detection, time-of-flight SIMS, spectroscopic ellipsometry, x-ray photoelectron spectroscopy. The results have shown a spread in thickness of oxide layer, ranging from unmeasurable to 1.6 nm. The data must be considered as preliminary at this stage, but give some insight into the suitability of the techniques and a general idea of the significance of impurities at the monolayer level. These measurements have been carried out on a small number of silicon surfaces both semiconductor grade <111> crystalline material and silicon which has been used in sphere fabrication. 5 refs., 1 fig.
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Evaluation of hydrogen and oxygen impurity levels on silicon surfaces
Energy Technology Data Exchange (ETDEWEB)
Kenny, M J; Wielunski, L S; Netterfield, R P; Martin, P J; Leistner, A [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics
1997-12-31
This paper reports on surface analytical techniques used to quantify surface concentrations of impurities such as oxygen and hydrogen. The following analytical techniques were used: Rutherford and Backscattering, elastic recoil detection, time-of-flight SIMS, spectroscopic ellipsometry, x-ray photoelectron spectroscopy. The results have shown a spread in thickness of oxide layer, ranging from unmeasurable to 1.6 nm. The data must be considered as preliminary at this stage, but give some insight into the suitability of the techniques and a general idea of the significance of impurities at the monolayer level. These measurements have been carried out on a small number of silicon surfaces both semiconductor grade <111> crystalline material and silicon which has been used in sphere fabrication. 5 refs., 1 fig.
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Long term high flow heated oxygen treatment in COPD – lung function and physical ability
DEFF Research Database (Denmark)
Weinreich, Ulla; Storgaard, Line; Hockey, Hans
2017-01-01
Introduction: Long term oxygen therapy (LTOT) improves survival in patients with COPD with resting hypoxemia. Despite this, a progressive loss of lung function and physical ability is expected in COPD. The AIRVO device delivers nasal high flow (NHF) warmed and humidified oxygen-enriched air, 20...
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The use of high-flow nasal oxygen in COPD patients
Directory of Open Access Journals (Sweden)
Silva Santos P
2016-09-01
Full Text Available Pedro Silva Santos,1 Antonio M Esquinas21Pulmonology Unit, Centro Hospitalar e Universitário de Coimbra – Hospitais da Universidade de Coimbra, Coimbra, Portugal; 2Internsive Care Unit, Hospital Morales Meseguer, Múrcia, SpainHigh-flow nasal cannula (HFNC oxygen therapy is an innovative and useful mode for the treatment of patients with respiratory failure.1–3 It delivers heated and humidified air providing higher and more expected gas flow rates and fraction inspired oxygen (FiO2 than traditional oxygen therapy.2 We read the article by Bräunlich et al1 carefully and congratulate the authors on their study about the use of nasal high-flow therapy in COPD patients. There are, however, some limitations to the study that need to be considered. First, this study has a small number of patients, particularly in groups A and B, which in our opinion will affect the comparison of data with the group C that contains a greater variety of patients with more severe outcomes, including forced expiratory volume in 1 second and forced vital capacity. Second, as a study on mean airway pressure, it would be interesting to evaluate partial pressure of CO2 with higher flows. Third, one of the aims of this study was to characterize changes in hypercapnia, so it is not correct to include nonhypercapnic patients. Fourth, it would be interesting to know the FiO2 that was given and whether the patients had domiciliary oxygen or noninvasive ventilation, as most of them are hypercapnic patients. Finally, regarding comfort and dyspnea scale, HFNC showed better results, which may increase its use when intolerant to noninvasive ventilation. In short, HFNC is an interesting mode for the future treatment of COPD patients with respiratory failure, which may lead to larger and randomized trials to confirm this indication.View original paper by Bräunlich et al.
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Differences in breast tissue oxygenation following radiotherapy
International Nuclear Information System (INIS)
Dornfeld, Ken; Gessert, Charles E.; Renier, Colleen M.; McNaney, David D.; Urias, Rodolfo E.; Knowles, Denise M.; Beauduy, Jean L.; Widell, Sherry L.; McDonald, Bonita L.
2011-01-01
Tissue perfusion and oxygenation changes following radiotherapy may result from and/or contribute to the toxicity of treatment. Breast tissue oxygenation levels were determined in the treated and non-treated breast 1 year after radiotherapy for breast conserving treatment. Transcutaneous oxygenation varied between subjects in both treated and non-treated breast. Subjects without diabetes mellitus (n = 16) had an average oxygenation level of 64.8 ± 19.9 mmHg in the irradiated breast and an average of 72.3 ± 18.1 mmHg (p = 0.018) at the corresponding location in the control breast. Patients with diabetes (n = 4) showed a different oxygenation pattern, with lower oxygenation levels in control tissue and no decrease in the irradiated breast. This study suggests oxygenation levels in normal tissues vary between patients and may respond differently after radiotherapy.
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International Nuclear Information System (INIS)
Hackbarth, S; Schlothauer, J; Preuss, A; Röder, B
2013-01-01
For the first time singlet oxygen luminescence kinetics in living cells were detected at high precision using LED light for excitation. As LED technology evolves, the light intensity emitted by standard LEDs allows photosensitized singlet oxygen luminescence detection in solution and cell suspensions. We present measurements superior to those of most actual laser powered setups regarding precision of singlet oxygen kinetics in solutions and cell suspensions. Data presented here show that LED based setups allow the determination of the photosensitizer triplet and singlet oxygen decay times in vitro with an accuracy of 0.1 μs. This enables monitoring of the photosensitizer efficiency and interaction with the cellular components using illumination doses small enough not to cause cell death. (letter)
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Ambient oxygen promotes tumorigenesis.
Directory of Open Access Journals (Sweden)
Ho Joong Sung
2011-05-01
Full Text Available Oxygen serves as an essential factor for oxidative stress, and it has been shown to be a mutagen in bacteria. While it is well established that ambient oxygen can also cause genomic instability in cultured mammalian cells, its effect on de novo tumorigenesis at the organismal level is unclear. Herein, by decreasing ambient oxygen exposure, we report a ∼50% increase in the median tumor-free survival time of p53-/- mice. In the thymus, reducing oxygen exposure decreased the levels of oxidative DNA damage and RAG recombinase, both of which are known to promote lymphomagenesis in p53-/- mice. Oxygen is further shown to be associated with genomic instability in two additional cancer models involving the APC tumor suppressor gene and chemical carcinogenesis. Together, these observations represent the first report directly testing the effect of ambient oxygen on de novo tumorigenesis and provide important physiologic evidence demonstrating its critical role in increasing genomic instability in vivo.
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Brain magnetic resonance imaging with contrast dependent on blood oxygenation
International Nuclear Information System (INIS)
Ogawa, S.; Lee, T.M.; Kay, A.R.; Tank, D.W.
1990-01-01
Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradient-echo techniques in high yields, the authors demonstrate in vivo images of brain microvasculature with image contrast reflecting the blood oxygen level. This blood oxygenation level-dependent (BOLD) contrast follows blood oxygen changes induced by anesthetics, by insulin-induced hypoglycemia, and by inhaled gas mixtures that alter metabolic demand or blood flow. The results suggest that BOLD contrast can be used to provide in vivo real-time maps of blood oxygenation in the brain under normal physiological conditions. BOLD contrast adds an additional feature to magnetic resonance imaging and complement other techniques that are attempting to provide position emission tomography-like measurements related to regional neural activity
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Capillary-oxygenation-level-dependent near-infrared spectrometry in frontal lobe of humans
Rasmussen, Peter; Dawson, Ellen A.; Nybo, Lars; van Lieshout, Johannes J.; Secher, Niels H.; Gjedde, Albert
2007-01-01
Brain function requires oxygen and maintenance of brain capillary oxygenation is important. We evaluated how faithfully frontal lobe near-infrared spectroscopy (NIRS) follows haemoglobin saturation (SCap) and how calculated mitochondrial oxygen tension (PMitoO2) influences motor performance. Twelve
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International Nuclear Information System (INIS)
Bullen, D.B.; Gdowski, G.E.
1988-08-01
Three copper-based alloys and three iron- to nickel-based austenitic alloys are being considered as possible materials for fabrication of high-level radioactive-waste disposal containers. The waste will include spent fuel assemblies from reactors as well as high-level waste in borosilicate glass and will be sent to the prospective site at Yucca Mountain, Nevada, for disposal. The copper-based alloy materials are CDA 102 (oxygen-free copper), CDA 613 (Cu-7Al), and CDA 715 (Cu-30Ni). The austenitic materials are Types 304L and 316L stainless steels and Alloy 825. The waste-package containers must maintain substantially complete containment for at least 300 yr and perhaps as long as 1000 yr, and they must be retrievable from the disposal site during the first 50 yr after emplacement. The containers will be exposed to high temperatures and high gamma radiation fields from the decay of high-level waste. This volume surveys the available data on the phase stability of both groups of candidate alloys. The austenitic alloys are reviewed in terms of the physical metallurgy of the iron-chromium-nickel system, martensite transformations, carbide formation, and intermetallic-phase precipitation. The copper-based alloys are reviewed in terms of their phase equilibria and the possibility of precipitation of the minor alloying constituents. For the austenitic materials, the ranking based on phase stability is: Alloy 825 (best), Type 316L stainless steel, and then Type 304L stainless steel (worst). For the copper-based materials, the ranking is: CDA 102 (oxygen-free copper) (best), and then both CDA 715 and CDA 613. 75 refs., 24 figs., 6 tabs
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Natural oxygenation of Champagne wine during ageing on lees: A metabolomics picture of hormesis.
Roullier-Gall, Chloé; Witting, Michael; Moritz, Franco; Gil, Ryan B; Goffette, Delphine; Valade, Michel; Schmitt-Kopplin, Philippe; Gougeon, Régis D
2016-07-15
The oxygenation of Champagne wine after 4 and 6 years of aging on lees in bottle was investigated by FTICR-MS and UPLC-Q-TOF-MS. Three levels of permeability were considered for the stoppers, ranging from 0.2 to 1.8 mg/L/year of oxygen transfer rate. Our results confirmed a good repeatability of ultra-high resolution FTICR-MS, both in terms of m/z and coefficient of variation of peak intensities among biological replicates. Vintages appeared to be the most discriminated features, and metabolite annotations suggested that the oldest wines (2006) were characterized by a higher sensitivity towards oxygenation. Within each vintage, the oxygenation mechanisms appeared to be different for low and high ingresses of oxygen, in agreement with the hormesis character of wine oxygenation. In the particular case of single variety wines and for a given level of stopper permeability, our results also showed that variety discrimination could be easily achieved among wines. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Effects of massive transfusion on oxygen availability
Directory of Open Access Journals (Sweden)
José Otávio Costa Auler Jr
Full Text Available OBJECTIVE: To determine oxygen derived parameters, hemodynamic and biochemical laboratory data (2,3 Diphosphoglycerate, lactate and blood gases analysis in patients after cardiac surgery who received massive blood replacement. DESIGN: Prospective study. SETTING: Heart Institute (Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Brazil. PARTICIPANTS: Twelve patients after cardiac surgery who received massive transfusion replacement; six of them evolved to a fatal outcome within the three-day postoperative follow-up. MEASUREMENTS AND MAIN RESULTS: The non-survivors group (n=6 presented high lactate levels and low P50 levels, when compared to the survivors group (p<0.05. Both groups presented an increase in oxygen consumption and O2 extraction, and there were no significant differences between them regarding these parameters. The 2,3 DPG levels were slightly reduced in both groups. CONCLUSIONS: This study shows that patients who are massively transfused following cardiovascular surgery present cell oxygenation disturbances probably as a result of O2 transport inadequacy.
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Experimental and analytical study of oxygen depletion in stirred cell suspensions
International Nuclear Information System (INIS)
Whillans, D.W.; Rauth, A.M.
1980-01-01
The determination and maintenance of constant low but non-zero levels of oxygen is critical in the study of the radiation chemical interactions of nitroimidazoles in mammalian cells in vitro. As well, many of these chemicals have increased toxicity toward hypoxic compared to aerobic cells, although absolute hypoxia probably is not required. Both of these phenomena must be investigated in systems where significant consumption of oxygen takes place, either through radiation depletion or by cellular metabolism. In this paper an analysis has been made of the form of oxygen depletion in stirred cell suspensions with overlying gas phase, and it has been found to conform to the relationship (C[t] - C/sub infinity/) = (C[0] - C/sub infinity/) exp(-k 1 t), where C/sub infinity/ = C/sub g/ - R/k 1 . Here C[t] is the oxygen tension throughout the solution; C/sub g/, the equivalent level in the overlying gas phase; R (concentration units per sec), the depletion rate; k 1 (sec/sup -1/), a physical constant independent of oxygen concentration and depletion rate; and C/sub infinity/, the oxygen level in solution approached at long times. This relationship has been confirmed in detail using a Clark-type oxygen sensor and a high-stability amplifier design due to Koch. Since oxygen levels down to a few hundred parts per million can be determined with accuracy, it has been possible to measure precisely the oxygen levels present in our experimental systems. Implications of these results for the interpretation of data obtained in stirred cell suspension with overlying gas phase under conditions of consumption are discussed
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Mitani, K.; Seki, K.; Keika, K.; Gkioulidou, M.; Lanzerotti, L. J.; Mitchell, D. G.; Kletzing, C.
2017-12-01
It is known that proton is main contributor of the ring current and oxygen ions can make significant contribution during major magnetic storms. Ions are supplied to the ring current by radial transport from the plasma sheet. Convective transport of lower-energy protons and diffusive transport of higher-energy protons were reported to contribute to the storm-time and quiet-time ring current respectively [e.g., Gkioulidou et al., 2016]. However, supply mechanisms of the oxygen ions are not clear. To characterize the supply of oxygen ions to the ring current during magnetic storms, we studied the properties of energetic proton and oxygen ion phase space densities (PSDs) for specific magnetic moment (μ) during the April 23-25, 2013, geomagnetic storm observed by the Van Allen Probes mission. We here report on radial transport of high-energy (μ ≥ 0.5 keV/nT) oxygen ions into the deep inner magnetosphere during the late main phase of the magnetic storm. Since protons show little change during this period, this oxygen radial transport is inferred to cause the development of the late main phase. Enhancement of poloidal magnetic fluctuations is simultaneously observed. We estimated azimuthal mode number ≤5 by using cross wavelet analysis with ground-based observation of IMAGE ground magnetometers. The fluctuations can resonate with drift and bounce motions of the oxygen ions. The results suggest that combination of the drift and drift-bounce resonances is responsible for the radial transport of high-energy oxygen ions into the deep inner magnetosphere. We also report on the radial transport of the high-energy oxygen ions into the deep inner magnetosphere during other magnetic storms.
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Energy Technology Data Exchange (ETDEWEB)
Duan, Li; Du, Lili; Liu, Wenyuan; Liu, Zhichao [Northwest Institute of Nuclear Technology, Xi' an, Shaanxi (China); Jia, Yi; Li, Junbai [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Colloid Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing (China)
2015-01-07
The effect of radioactive UO{sub 2}{sup 2+} on the oxygen-transporting capability of hemoglobin-based oxygen carriers has been investigated in vitro. The hemoglobin (Hb) microspheres fabricated by the porous template covalent layer-by-layer (LbL) assembly were utilized as artificial oxygen carriers and blood substitutes. Magnetic nanoparticles of iron oxide (Fe{sub 3}O{sub 4}) were loaded in porous CaCO{sub 3} particles for magnetically assisted chemical separation (MACS). Through the adsorption spectrum of magnetic Hb microspheres after adsorbing UO{sub 2}{sup 2+}, it was found that UO{sub 2}{sup 2+} was highly loaded in the magnetic Hb microspheres, and it shows that the presence of UO{sub 2}{sup 2+} in vivo destroys the structure and oxygen-transporting capability of Hb microspheres. In view of the high adsorption capacity of UO{sub 2}{sup 2+}, the as-assembled magnetic Hb microspheres can be considered as a novel, highly effective adsorbent for removing metal toxins from radiation-contaminated bodies, or from nuclear-power reactor effluent before discharge into the environment. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
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2015-10-13
412TW-PA-15560 Electrochemical Separation, Pumping, and Storage of Hydrogen or Oxygen into Nanocapillaries Via High Pressure MEA Seals...TITLE AND SUBTITLE Electrochemical Separation, Pumping, and Storage of Hydrogen or Oxygen into Nanocapillaries Via High Pressure MEA Seals...density storage of gases remains a major technological hurdle for many fields. The U.S. Department of Energy (DOE), for example, reduced their hydrogen
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Energy Technology Data Exchange (ETDEWEB)
Ding, Jiule; Xing, Wei; Chen, Jie; Pan, Liang; Sun, Jun; Xing, Shi Jun [Dept. of Radiology, Third Affiliated Hospital of Suzhou University, Changzhou (China); Wu, Dong Mei [Shanghai Key Laboratory of Magnetic Resonance Imaging, East China Normal University, Shanghai (China); Dai, Yong Ming [Philips Healthcare, Shanghai (China)
2015-08-15
To assess the feasibility of susceptibility-weighted imaging (SWI) while monitoring changes in renal oxygenation level after water loading. Thirty-two volunteers (age, 28.0 ± 2.2 years) were enrolled in this study. SWI and multi-echo gradient echo sequence-based T2{sup *} mapping were used to cover the kidney before and after water loading. Cortical and medullary parameters were measured using small regions of interest, and their relative changes due to water loading were calculated based on baseline and post-water loading data. An intraclass correlation coefficient analysis was used to assess inter-observer reliability of each parameter. A receiver operating characteristic curve analysis was conducted to compare the performance of the two methods for detecting renal oxygenation changes due to water loading. Both medullary phase and medullary T2{sup *} values increased after water loading (p < 0.001), although poor correlations were found between the phase changes and the T2{sup *} changes (p > 0.05). Interobserver reliability was excellent for the T2{sup *} values, good for SWI cortical phase values, and moderate for the SWI medullary phase values. The area under receiver operating characteristic curve of the SWI medullary phase values was 0.85 and was not different from the medullary T2{sup *} value (0.84). Susceptibility-weighted imaging enabled monitoring changes in the oxygenation level in the medulla after water loading, and may allow comparable feasibility to detect renal oxygenation level changes due to water loading compared with that of T2{sup *} mapping.
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Jones, B; Cooper, C E
2016-01-01
To date, measurements of oxygen status during swim exercise have focused upon systemic aerobic capacity. The development of a portable, waterproof NIRS device makes possible a local measurement of muscle hemodynamics and oxygenation that could provide a novel insight into the physiological changes that occur during swim exercise. The purpose of this study was to observe changes in muscle oxygenation in the vastus lateralis (VL) and latissimus dorsi (LD) of club level swimmers and triathletes. Ten subjects, five club level swimmers and five club level triathletes (three men and seven women) were used for assessment. Swim group; mean±SD=age 21.2±1.6 years; height 170.6±7.5 cm; weight 62.8±6.9 kg; vastus lateralis skin fold 13.8±5.6 mm; latissimus dorsi skin fold 12.6±3.7. Triathlete group; mean±SD=age 44.0±10.5 years; height 171.6±7.0 cm; weight 68.6±12.7 kg; vastus lateralis skin fold 11.8±3.5 mm; latissimus dorsi skin fold 11.2±3.1. All subjects completed a maximal 200 m freestyle swim, with the PortaMon, a portable NIR device, attached to the subject's dominant side musculature. ΔTSI% between the vastus lateralis and latissimus dorsi were analysed using either paired (2-tailed) t-tests or Wilcoxon signed rank test. The level of significance for analysis was set at pswim significantly faster (p=0.04) than club level triathletes. Club level swimmers use both the upper and lower muscles to a similar extent during a maximal 200 m swim. Club level triathletes predominately use the upper body for propulsion during the same exercise. The data produced by NIRS in this study are the first of their kind and provide insight into muscle oxygenation changes during swim exercise which can indicate the contribution of one muscle compared to another. This also enables a greater understanding of the differences in swimming techniques seen between different cohorts of swimmers and potentially within individual swimmers.
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Nature of oxygen donors and radiation defects in oxygen-doped germanium
International Nuclear Information System (INIS)
Fukuoka, Noboru; Atobe, Kozo; Honda, Makoto; Matsuda, Koji.
1991-01-01
The nature of oxygen donors and radiation defects in oxygen-doped germanium were studied through measurements of the infrared absorption spectrum, deep level transient spectroscopy spectrum and carrier concentration. It is revealed that a new donor is not formed in oxygen-doped germanium. An A-center (interstitial oxygen-vacancy pair) forms a complex with a thermal donor in its annealing stage at 60degC-140degC. The introduction rate of defects by 1.5 MeV electron irradiation was enhanced in thermal-donor-doped samples. (author)
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NOx emissions from high swirl turbulent spray flames with highly oxygenated fuels
Bohon, Myles; Roberts, William L.
2013-01-01
Combustion of fuels with fuel bound oxygen is of interest from both a practical and a fundamental viewpoint. While a great deal of work has been done studying the effect of oxygenated additives in diesel and gasoline engines, much less has been done
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International Nuclear Information System (INIS)
Tao, Z.; Alburger, D.E.; Jones, K.W.; Yao, Y.D.; Kao, Y.H.
1988-01-01
A new method for determining the oxygen content in high T/sub c/ superconductors has been demonstrated using a charged particle activation technique. This method allows a measurement of the concentration of 16 O atoms in the superconducting material by detection of the 17 F produced with the 16 O(d,n) 17 F nuclear reaction. By way of example, this technique is applied to the determination of oxygen content in a series of high T/sub c/ Y-Ba-Cu-O samples in which the stoichiometry is varied by reducing the copper concentration. The stabilized oxygen content shows a nonlinear dependence on the copper deficiency in these specimens
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International Nuclear Information System (INIS)
Maerk, T.D.; Matejcik, S.; Kiendler, A.; Cicman, P.; Senn, G.; Skalny, J.; Stampfli, P.; Illenberger, E.; Chu, Y.; Stamatovic, A.
1996-01-01
The processes of electron attachment to oxygen, ozone, ozone/oxygen cluster and oxygen cluster as well as other compounds of atmospheric relevance (CF 2 Cl 2 , CHCl 3 and CCl 3 Br) were studied with ultra-high energy resolution crossed beam technique
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Negative blood oxygen level dependent signals during speech comprehension.
Rodriguez Moreno, Diana; Schiff, Nicholas D; Hirsch, Joy
2015-05-01
Speech comprehension studies have generally focused on the isolation and function of regions with positive blood oxygen level dependent (BOLD) signals with respect to a resting baseline. Although regions with negative BOLD signals in comparison to a resting baseline have been reported in language-related tasks, their relationship to regions of positive signals is not fully appreciated. Based on the emerging notion that the negative signals may represent an active function in language tasks, the authors test the hypothesis that negative BOLD signals during receptive language are more associated with comprehension than content-free versions of the same stimuli. Regions associated with comprehension of speech were isolated by comparing responses to passive listening to natural speech to two incomprehensible versions of the same speech: one that was digitally time reversed and one that was muffled by removal of high frequencies. The signal polarity was determined by comparing the BOLD signal during each speech condition to the BOLD signal during a resting baseline. As expected, stimulation-induced positive signals relative to resting baseline were observed in the canonical language areas with varying signal amplitudes for each condition. Negative BOLD responses relative to resting baseline were observed primarily in frontoparietal regions and were specific to the natural speech condition. However, the BOLD signal remained indistinguishable from baseline for the unintelligible speech conditions. Variations in connectivity between brain regions with positive and negative signals were also specifically related to the comprehension of natural speech. These observations of anticorrelated signals related to speech comprehension are consistent with emerging models of cooperative roles represented by BOLD signals of opposite polarity.
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Rodenas-Rochina, Joaquin; Kelly, Daniel J; Gómez Ribelles, Jose Luis; Lebourg, Myriam
2017-06-01
Chondrogenesis of mesenchymal stem cells (MSCs) is known to be regulated by a number of environmental factors, including local oxygen levels. The hypothesis of this study is that the response of MSCs to hypoxia is dependent on the physical and chemical characteristics of the substrate used. The objective of this study was to explore how different modifications to polycaprolactone (PCL) scaffolds influenced the response of MSCs to hypoxia. PCL, PCL-hyaluronic acid (HA), and PCL-Bioglass ® (BG) scaffolds were seeded with MSCs derived from bone marrow and cultured for 35 days under normoxic or low oxygen conditions, and the resulting biochemical properties of the MSC laden construct were assessed. Low oxygen tension has a positive effect over cell proliferation and macromolecules biosynthesis. Furthermore, hypoxia enhanced the distribution of collagen and glycosaminoglycans (GAGs) deposition through the scaffold. On the other hand, MSCs displayed certain material dependent responses to hypoxia. Low oxygen tension had a positive effect on cell proliferation in BG and HA scaffolds, but only a positive effect on GAGs synthesis in PCL and HA scaffolds. In conclusion, hypoxia increased cell viability and expression of chondrogenic markers but the cell response was modulated by the type of scaffold used. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1684-1691, 2017. © 2017 Wiley Periodicals, Inc.
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Directory of Open Access Journals (Sweden)
Lee Na
2011-05-01
Full Text Available Abstract Background Helicobacter pylori (Hp, a human pathogen that is associated with gastritis, peptic ulcer, and gastric cancer, has been considered a microaerophile, but there is no general consensus about its specific O2 requirements. A clear understanding of Hp physiology is needed to elucidate the pathogenic mechanism(s of Hp infection. Results We cultured Hp under a range of O2 levels with or without 10% CO2 and evaluated growth profiles, morphology, intracellular pH, and energy metabolism. We found that, in the presence of 10% CO2, the normal atmospheric level of O2 inhibited Hp growth at low density but stimulated growth at a higher density. Field emission scanning electron microscopy and fluorescence microscopy of Hp cells cultured under 20% O2 tension revealed live spiral-shaped bacteria with outer membrane vesicles on a rugged cell surface, which became smooth during the stationary phase. Fermentation products including acetate, lactate, and succinate were detected in cell culture media grown under microaerobic conditions, but not under the aerobic condition. CO2 deprivation for less than 24 h did not markedly change cytoplasmic or periplasmic pH, suggesting that cellular pH homeostasis alone cannot account for the capnophilic nature of Hp. Further, CO2 deprivation significantly increased intracellular levels of ppGpp and ATP but significantly decreased cellular mRNA levels, suggesting induction of the stringent response. Conclusions We conclude, unlike previous reports, that H. pylori may be a capnophilic aerobe whose growth is promoted by atmospheric oxygen levels in the presence of 10% CO2. Our data also suggest that buffering of intracellular pH alone cannot account for the CO2 requirement of H. pylori and that CO2 deprivation initiates the stringent response in H. pylori. Our findings may provide new insight into the physiology of this fastidious human pathogen.
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Yang, Wenge; Kim, Duck Young; Yang, Liuxiang; Li, Nana; Tang, Lingyun; Amine, Khalil; Mao, Ho-Kwang
2017-09-01
The lithium-air battery has great potential of achieving specific energy density comparable to that of gasoline. Several lithium oxide phases involved in the charge-discharge process greatly affect the overall performance of lithium-air batteries. One of the key issues is linked to the environmental oxygen-rich conditions during battery cycling. Here, the theoretical prediction and experimental confirmation of new stable oxygen-rich lithium oxides under high pressure conditions are reported. Three new high pressure oxide phases that form at high temperature and pressure are identified: Li 2 O 3 , LiO 2 , and LiO 4 . The LiO 2 and LiO 4 consist of a lithium layer sandwiched by an oxygen ring structure inherited from high pressure ε-O 8 phase, while Li 2 O 3 inherits the local arrangements from ambient LiO 2 and Li 2 O 2 phases. These novel lithium oxides beyond the ambient Li 2 O, Li 2 O 2 , and LiO 2 phases show great potential in improving battery design and performance in large battery applications under extreme conditions.
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Figoni, Stephen F.
The purpose of this study was to assess selected central cardiovascular functions of spinal cord injured, quadriplegic subjects at varying levels of oxygen uptake (VO sub 2). Subjects included 11 untrained, male college students with C5, C6, or C7 complete quadriplegia and 11 able-bodied reference subjects. Exercise was performed on a Monark cycle…
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Low-Flammability PTFE for High-Oxygen Environments
Walle, E.; Fallon, B.; Sheppard, A.
1986-01-01
Modified forming process removes volatile combustible materials. Flammability of cable-wrapping tape reduced by altering tape-manufacturing process. In new manufacturing process, tape formed by proprietary process of screw extrusion, followed by washing in solvent and drying. Tape then wrapped as before. Spectrogram taken after extrusion, washing, and drying shows lower hydrocarbon content. PTFE formed by new process suited to oxygen-rich environments. Safe in liquid oxygen of Space Shuttle tank and in medical uses; thin-wall shrinkable tubing in hospital test equipment, surgical instruments, and implants.
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DEFF Research Database (Denmark)
Kjærgaard, Christian Hauge; Rossmeisl, Jan; Nørskov, Jens Kehlet
2010-01-01
In this paper, we present a method to directly compare the energy levels of intermediates in enzymatic and inorganic oxygen reduction catalysts. We initially describe how the energy levels of a Pt(111) catalyst, operating at pH = 0, are obtained. By a simple procedure, we then convert the energy...... levels of cytochrome c oxidase (CcO) models obtained at physiological pH = 7 to the energy levels at pH = 0, which allows for comparison. Furthermore, we illustrate how different bias voltages will affect the free-energy landscapes of the catalysts. This allows us to determine the so-called theoretical...
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Kinetics of the high temperature oxygen exchange reaction on 238PuO2 powder
International Nuclear Information System (INIS)
Whiting, Christofer E.; Du, Miting; Felker, L. Kevin; Wham, Robert M.; Barklay, Chadwick D.; Kramer, Daniel P.
2015-01-01
Oxygen exchange reactions performed on PuO 2 suggest the reaction is influenced by at least three mechanisms: an internal chemical reaction, surface mobility of active species/defects, and surface exchange of gaseous oxygen with lattice oxygen. Activation energies for the surface mobility and internal chemical reaction are presented. Determining which mechanism is dominant appears to be a complex function including at least specific surface area and temperature. Thermal exposure may also impact the oxygen exchange reaction by causing reductions in the specific surface area of PuO 2 . Previous CeO 2 surrogate studies exhibit similar behavior, confirming that CeO 2 is a good qualitative surrogate for PuO 2 , in regards to the oxygen exchange reaction. Comparison of results presented here with previous work on the PuO 2 oxygen exchange reaction allows complexities in the previous work to be explained. These explanations allowed new conclusions to be drawn, many of which confirm the conclusions presented here. - Highlights: • PuO 2 Oxygen exchange kinetics can be influenced by at least 3 different mechanisms. • An internal chemical reaction controls the rate at high temperature and large SSA. • Surface mobility and surface exchange influence rate at lower temperatures and SSA. • Exchange temperatures may alter SSA and make data difficult to interpret.
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International Nuclear Information System (INIS)
Vizkelethy, G.; Revesz, P.
1993-01-01
The quantification of oxygen and carbon in high-temperature (T c ) superconducting oxide thin films was made by employing elastic resonance in He backscattering analysis. A method combining the oxygen resonance technique and channeling was presented for measuring the nature of the oxygen disorder near the surface and the interface in a YBCO superconducting film grown on an MgO substrate. The oxygen resonance technique was used to quantify the oxygen profiling in the metal/YBCO contacts, showing that Zr and Nb act as sinks to oxygen from YBCO films and are oxidized in the forms Zr/ZrO 2 /YBCO/MgO and Nb 0.2 O/YBCO/MgO after annealing in a vacuum at 350 o C. We combined the carbon and oxygen resonances to determine the carbon contamination and oxygen concentration changes on the YBCO surface after coating and baking the photoresist. Residual carbon on the surface and a thin layer of oxygen depletion near the YBCO surface have been observed. The residual carbon in Bi 2 Sr 2 CaCu 2 O 8 films made by the decomposition of metallo-organic precursors was quantified using carbon resonance. (author)
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Keskin, Kudret; Kilci, Hakan; Aksan, Gökhan; Çetinkal, Gökhan; Yıldız, Süleyman Sezai; Kocaman Türk, Füsun; Bingöl, Gülsüm
2017-09-01
Oxidative stress (OS) is involved in the pathogenesis of atherosclerosis. Hyperbaric oxygen therapy (HBOT), in which 100% oxygen is inhaled under hyperbaric pressure, may create OS. Therefore, the aim of this research was to measure the serum oxidized low-density lipoprotein (oxLDL) level in patients undergoing HBOT. Twenty-nine patients who underwent HBOT to treat various diseases were enrolled in this study. The serum oxLDL level was measured at the beginning of the first and after the 10th therapy session. There was no significant difference between the oxLDL level of patients before and after HBOT (4.96±0.1 vs. 4.94±0.1 U/mL; p=0.36). HBOT seems to be safe in terms of oxLDL production up to 10 sessions. However, further large-scale studies investigating longer duration of HBOT treatment are required to understand the role of OS.
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Lerner, Sorin; Kundu, Sudipta
2011-01-01
Given the growing size and heterogeneity of Systems on Chip (SOC), the design process from initial specification to chip fabrication has become increasingly complex. This growing complexity provides incentive for designers to use high-level languages such as C, SystemC, and SystemVerilog for system-level design. While a major goal of these high-level languages is to enable verification at a higher level of abstraction, allowing early exploration of system-level designs, the focus so far for validation purposes has been on traditional testing techniques such as random testing and scenario-based
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Solubility of oxygen in a seawater medium in equilibrium with a high-pressure oxy-helium atmosphere.
Taylor, C D
1979-06-01
The molar oxygen concentration in a seawater medium in equilibrium with a high-pressure oxygen-helium atmosphere was measured directly in pressurized subsamples, using a modified version of the Winkler oxygen analysis. At a partial pressure of oxygen of 1 atm or less, its concentration in the aqueous phase was adequately described by Henry's Law at total pressures up to 600 atm. This phenomenon, which permits a straightforward determination of dissolved oxygen within hyperbaric systems, resulted from pressure-induced compensatory alterations in the Henry's Law variables rather than from a true obedience to the Ideal Gas Law. If the partial pressure of a gas contributes significantly to the hydrostatic pressure, Henry's Law is no longer adequate for determining its solubility within the compressed medium.
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Coherent spin-rotational dynamics of oxygen superrotors
Milner, Alexander A.; Korobenko, Aleksey; Milner, Valery
2014-09-01
We use state- and time-resolved coherent Raman spectroscopy to study the rotational dynamics of oxygen molecules in ultra-high rotational states. While it is possible to reach rotational quantum numbers up to N≈ 50 by increasing the gas temperature to 1500 K, low population levels and gas densities result in correspondingly weak optical response. By spinning {{O}2} molecules with an optical centrifuge, we efficiently excite extreme rotational states with N≤slant 109 in high-density room temperature ensembles. Fast molecular rotation results in the enhanced robustness of the created rotational wave packets against collisions, enabling us to observe the effects of weak spin-rotation coupling in the coherent rotational dynamics of oxygen. The decay rate of spin-rotational coherence due to collisions is measured as a function of the molecular angular momentum and its dependence on the collisional adiabaticity parameter is discussed. We find that at high values of N, the rotational decoherence of oxygen is much faster than that of the previously studied non-magnetic nitrogen molecules, pointing at the effects of spin relaxation in paramagnetic gases.
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Study of high energy ion implantation of boron and oxygen in silicon
International Nuclear Information System (INIS)
Thevenin, P.
1991-06-01
Three aspects of high energy (0.5-3 MeV) light ions ( 11 B + and 16 O + ) implantation in silicon are examined: (1)Spatial repartition; (2) Target damage and (3) Synthesis by oxygen implantation of a buried silicon oxide layer
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Numeric Simulation of Oxygen Enriched Combustion in a Frit Melting Kiln
Directory of Open Access Journals (Sweden)
Bernardo A. Herrera-Múnera
2013-11-01
Full Text Available In this paper, a numerical study of air enriched combustion on a natural gas rotary furnace for frita melting is presented. This study was done with the aim of determining an oxygen concentration to ensure economic feasibility of the process without affecting quality requirements. The simulations were conducted using the commercial software ANSYS FLUENT as a design tool to predict the behavior of the thermal system and to establish operations conditions with different oxygen enrichment levels. Finite Rate / Eddy Dissipation model was used for combustion simulation, while k - ε Realizable and Discrete Ordinates models were utilized for turbulence and radiation simulation, respectively. It was found that an enrichment level close to 31% of oxygen in the air allows for reaching temperatures for frita melting larger than 1700 K. In this way, current consumption of high purity oxygen can be diminished without affecting the production levels and the quality of the product.
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International Nuclear Information System (INIS)
Mao, L.F.; Wang, Z.O.
2008-01-01
HfO 2 high-K gate dielectric has been used as a new gate dielectric in metal-oxide-semiconductor structures. First-principles simulations are used to study the effects of oxygen vacancies on the tunneling current through the oxide. A level which is nearly 1.25 eV from the bottom of the conduction band is introduced into the bandgap due to the oxygen vacancies. The tunneling current calculations show that the tunneling currents through the gate oxide with different defect density possess the typical characteristic of stress-induced leakage current. Further analysis shows that the location of oxygen vacancies will have a marked effect on the tunneling current. The largest increase in the tunneling current caused by oxygen vacancies comes about at the middle oxide field when defects are located at the middle of the oxide. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
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Clinical evidence on high flow oxygen therapy and active humidification in adults.
Gotera, C; Díaz Lobato, S; Pinto, T; Winck, J C
2013-01-01
Recently there has been growing interest in an alternative to conventional oxygen therapy: the heated, humidified high flow nasal cannula oxygen therapy (HFNC). A number of physiological effects have been described with HFNC: pharyngeal dead space washout, reduction of nasopharyngeal resistance, a positive expiratory pressure effect, an alveolar recruitment, greater humidification, more comfort and better tolerance by the patient, better control of FiO2 and mucociliary clearance. There is limited experience of HFNC in adults. There are no established guidelines or decision-making pathways to guide use of the HFNC therapy for adults. In this article we review the existing evidence of HFNC oxygen therapy in adult patients, its advantages, limitations and the current literature on clinical applications. Further research is required to determine the long-term effect of this therapy and identify the adult patient population to whom it is most beneficial. Copyright © 2013 Sociedade Portuguesa de Pneumologia. Published by Elsevier España. All rights reserved.
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Material Usage in High Pressure Oxygen Systems for the International Space Station
Kravchenko, Michael; Sievers, D. Elliott
2014-01-01
The Nitrogen/Oxygen Recharge System (NORS) for the International Space Station (ISS) Program was required as part of the Space Shuttle retirement efforts to sustain the ISS life support systems. The system is designed around a 7000 psia Oxygen or Nitrogen Recharge Tank Assembly which is able to be utilized both internally and externally to the ISS. Material selection and usage were critical to ensure oxygen compatibility for the design, while taking into consideration toxicity, weldability, brazability and general fabrication and assembly techniques. The system uses unique hardware items such a composite overwrap pressure vessel (COPV), high pressure mechanical gauges, compact regulators and valves, quick disconnects, metal tubing and flexhoses. Numerous challenges and anomalies were encountered due to the exotic nature of this project which will be discussed in detail. The knowledge gained from these anomalies and failure resolutions can be applied to more than space applications, but can also be applicable to industry pressurized systems.
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Pássaro, Caroline P; Silva, Pedro L; Rzezinski, Andréia F; Abrantes, Simone; Santiago, Viviane R; Nardelli, Liliane; Santos, Raquel S; Barbosa, Carolina M L; Morales, Marcelo M; Zin, Walter A; Amato, Marcelo B P; Capelozzi, Vera L; Pelosi, Paolo; Rocco, Patricia R M
2009-03-01
To investigate the effects of low and high levels of positive end-expiratory pressure (PEEP), without recruitment maneuvers, during lung protective ventilation in an experimental model of acute lung injury (ALI). Prospective, randomized, and controlled experimental study. University research laboratory. Wistar rats were randomly assigned to control (C) [saline (0.1 mL), intraperitoneally] and ALI [paraquat (15 mg/kg), intraperitoneally] groups. After 24 hours, each group was further randomized into four groups (six rats each) at different PEEP levels = 1.5, 3, 4.5, or 6 cm H2O and ventilated with a constant tidal volume (6 mL/kg) and open thorax. Lung mechanics [static elastance (Est, L) and viscoelastic pressure (DeltaP2, L)] and arterial blood gases were measured before (Pre) and at the end of 1-hour mechanical ventilation (Post). Pulmonary histology (light and electron microscopy) and type III procollagen (PCIII) messenger RNA (mRNA) expression were measured after 1 hour of mechanical ventilation. In ALI group, low and high PEEP levels induced a greater percentage of increase in Est, L (44% and 50%) and DeltaP2, L (56% and 36%) in Post values related to Pre. Low PEEP yielded alveolar collapse whereas high PEEP caused overdistension and atelectasis, with both levels worsening oxygenation and increasing PCIII mRNA expression. In the present nonrecruited ALI model, protective mechanical ventilation with lower and higher PEEP levels than required for better oxygenation increased Est, L and DeltaP2, L, the amount of atelectasis, and PCIII mRNA expression. PEEP selection titrated for a minimum elastance and maximum oxygenation may prevent lung injury while deviation from these settings may be harmful.
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Directory of Open Access Journals (Sweden)
Gurkirat Sandhu
2017-01-01
Full Text Available Context: Periodontal surgical procedures produce varying degree of stress in all patients. Nitrous oxide-oxygen inhalation sedation is very effective for adult patients with mild-to-moderate anxiety due to dental procedures and needle phobia. Aim: The present study was designed to perform periodontal surgical procedures under nitrous oxide-oxygen inhalation sedation and assess whether this technique actually reduces stress physiologically, in comparison to local anesthesia alone (LA during lengthy periodontal surgical procedures. Settings and Design: This was a randomized, split-mouth, cross-over study. Materials and Methods: A total of 16 patients were selected for this randomized, split-mouth, cross-over study. One surgical session (SS was performed under local anesthesia aided by nitrous oxide-oxygen inhalation sedation, and the other SS was performed on the contralateral quadrant under LA. For each session, blood samples to measure and evaluate serum cortisol levels were obtained, and vital parameters including blood pressure, heart rate, respiratory rate, and arterial blood oxygen saturation were monitored before, during, and after periodontal surgical procedures. Statistical Analysis Used: Paired t-test and repeated measure ANOVA. Results: The findings of the present study revealed a statistically significant decrease in serum cortisol levels, blood pressure and pulse rate and a statistically significant increase in respiratory rate and arterial blood oxygen saturation during periodontal surgical procedures under nitrous oxide inhalation sedation. Conclusion: Nitrous oxide-oxygen inhalation sedation for periodontal surgical procedures is capable of reducing stress physiologically, in comparison to LA during lengthy periodontal surgical procedures.
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Biogeochemistry: Oxygen burrowed away
Meysman, F.J.R.
2014-01-01
Multicellular animals probably evolved at the seafloor after a rise in oceanic oxygen levels. Biogeochemical model simulations suggest that as these animals started to rework the seafloor, they triggered a negative feedback that reduced global oxygen.
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Directory of Open Access Journals (Sweden)
Kathryn Maitland
2018-01-01
Full Text Available Background: In Africa, the clinical syndrome of pneumonia remains the leading cause of morbidity and mortality in children in the post-neonatal period. This represents a significant burden on in-patient services. The targeted use of oxygen and simple, non-invasive methods of respiratory support may be a highly cost-effective means of improving outcome, but the optimal oxygen saturation threshold that results in benefit and the best strategy for delivery are yet to be tested in adequately powered randomised controlled trials. There is, however, an accumulating literature about the harms of oxygen therapy across a range of acute and emergency situations that have stimulated a number of trials investigating permissive hypoxia. Methods: In 4200 African children, aged 2 months to 12 years, presenting to 5 hospitals in East Africa with respiratory distress and hypoxia (oxygen saturation or = 80% (permissive hypoxia; and High flow using AIrVO2TM compared with low flow delivery (routine care. Discussion: The overarching objective is to address the key research gaps in the therapeutic use of oxygen in resource-limited setting in order to provide a better evidence base for future management guidelines. The trial has been designed to address the poor outcomes of children in sub-Saharan Africa, which are associated with high rates of in-hospital mortality, 9-10% (for those with oxygen saturations of 80-92% and 26-30% case fatality for those with oxygen saturations <80%. Clinical trial registration: ISRCTN15622505 Trial status: Recruiting
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Highly Oxygenated Flavonoids from the Leaves of Nicotiana plumbaginifolia (Solanaceae)
Md. Shafiullah Shajib; Bidyut Kanti Datta; Md. Hossain Sohrab; Mohammad Abdur Rashid; Lutfun Nahar; Satyajit Dey Sarker
2017-01-01
Nicotiana plumbaginifolia Viv. is an annual herb of the family Solanaceae, which grows abundantly in the weedy lands of Bangladesh . This plant possesses analgesic, antibacterial, anti-anxiety and hepatoprotective properties, and produces various phenolic compounds including flavonoids. The present study afforded determination of total phenolic and flavonoid contents, and for the first time, the isolation and characterization of highly oxygenated flavonoids, e.g., 3,3' ,5,6,7,8-hexamethoxy- 4...
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Macroscopic results for a novel oxygenated silicon material
International Nuclear Information System (INIS)
Watts, S.J.; Da Via', C.; Karpenko, A.
2002-01-01
High-resistivity FZ silicon diodes have been processed in order to increase their oxygen dimer (O 2i ) concentration. Deep level transient spectroscopy measurements have been performed after proton irradiation showing that the formation of the VO centre is suppressed. The substrates had a starting resistivity of 2-4 kΩ cm, with an oxygen concentration of 10 15 and 10 17 cm -3 . Results for doping changes, leakage current and annealing behaviour after irradiation with 24 GeV/c protons are shown
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Retinal Vessel Oxygen Saturation during 100% Oxygen Breathing in Healthy Individuals.
Directory of Open Access Journals (Sweden)
Olof Birna Olafsdottir
Full Text Available To detect how systemic hyperoxia affects oxygen saturation in retinal arterioles and venules in healthy individuals.Retinal vessel oxygen saturation was measured in 30 healthy individuals with a spectrophotometric retinal oximeter (Oxymap T1. Oximetry was performed during breathing of room air, 100% oxygen (10 minutes, 6L/min and then again room air (10 minutes recovery.Mean oxygen saturation rises modestly in retinal arterioles during 100% oxygen breathing (94.5%±3.8 vs. 92.0%±3.7% at baseline, p<0.0001 and dramatically in retinal venules (76.2%±8.0% vs. 51.3%±5.6%, p<0.0001. The arteriovenous difference decreased during 100% oxygen breathing (18.3%±9.0% vs. 40.7%±5.7%, p<0.0001. The mean diameter of arterioles decreased during 100% oxygen breathing compared to baseline (9.7±1.4 pixels vs. 10.3±1.3 pixels, p<0.0001 and the same applies to the mean venular diameter (11.4±1.2 pixels vs. 13.3±1.5 pixels, p<0.0001.Breathing 100% oxygen increases oxygen saturation in retinal arterioles and more so in venules and constricts them compared to baseline levels. The dramatic increase in oxygen saturation in venules reflects oxygen flow from the choroid and the unusual vascular anatomy and oxygen physiology of the eye.
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Woods, H. Arthur; Moran, Amy L.; Arango, Claudia P.; Mullen, Lindy; Shields, Chris
2008-01-01
Compared to temperate and tropical relatives, some high-latitude marine species are large-bodied, a phenomenon known as polar gigantism. A leading hypothesis on the physiological basis of gigantism posits that, in polar water, high oxygen availability coupled to low metabolic rates relieves constraints on oxygen transport and allows the evolution of large body size. Here, we test the oxygen hypothesis using Antarctic pycnogonids, which have been evolving in very cold conditions (−1.8–0°C) for several million years and contain spectacular examples of gigantism. Pycnogonids from 12 species, spanning three orders of magnitude in body mass, were collected from McMurdo Sound, Antarctica. Individual sea spiders were forced into activity and their performance was measured at different experimental levels of dissolved oxygen (DO). The oxygen hypothesis predicts that, all else being equal, large pycnogonids should perform disproportionately poorly in hypoxia, an outcome that would appear as a statistically significant interaction between body size and oxygen level. In fact, although we found large effects of DO on performance, and substantial interspecific variability in oxygen sensitivity, there was no evidence for size×DO interactions. These data do not support the oxygen hypothesis of Antarctic pycnogonid gigantism and suggest that explanations must be sought in other ecological or evolutionary processes. PMID:19129117
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Testing and performance of electrolytic oxygen meters for use in liquid sodium
International Nuclear Information System (INIS)
Taylor, R.G.; Thompson, R.
1983-01-01
The performance of yttria-doped thoria ceramic electrochemical oxygen meters in liquid sodium is described. Tests were carried out using laboratory loops. Temperature coefficients of the oxygen meters have been measured between 380 0 C and 480 0 C, and the response to changes in oxygen level using cold-trap temperatures from 125 0 C to 250 0 C was determined. The ceramic has been shown to give good performance over lifetimes exceeding 400 days in some cases. The temperature coefficients and response to oxygen level changes are in good agreement with thermodynamic predictions. The effect of running the meters in high-oxygen sodium has been studied and a general mode of failure has been shown to be grain-boundary attack by oxygen/sodium solutions. The effect of #betta#-radiation on the meters has been studied. The meters with a metal/metal oxide reference electrode were unaffected by dose rates up to 52860 mGy h - 1 . Meters with an air reference electrode do show an effect as a voltage reduction at levels down to 2420 mGy h - 1 . This effect was temperature-dependent and was insignificant at 500 0 C. (orig.)
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Action of carbon monoxide on the affinity of hemoglobin for oxygen
Energy Technology Data Exchange (ETDEWEB)
Vanuxem, D.; Weiller, P.J.; Guillot, C.; Grimaud, C.
1982-01-01
The authors have studied the action of carbon monoxide on the affinity of hemoglobin for oxygen by measuring P50 in whole blood and in stripped hemoglobin before and after exposition of blood samples from heavy smokers and polycythemic patients with high levels of HbCO to hyperbaric oxygen (2.2 ata). The concentration of 2,3-diphosphoglycerate was normal although P50 was significantly lowered, not only in whole blood but also in stripped hemoglobin. Hyperbaric oxygen normalized P50 by removing CO radicals from stripped hemoglobin. This may indicate that CO radicals exert a direct action on the hemoglobin molecule, at least at the HbCO levels studied in this work.
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Olsson, Mats; Wilson, Mark; Uller, Tobias; Mott, Beth; Isaksson, Caroline
2009-01-01
Many organisms show differences between males and females in growth rate and crucial life history parameters, such as longevity. Considering this, we may expect levels of toxic metabolic by-products of the respiratory chain, such as reactive oxygen species (ROS), to vary with age and sex. Here, we analyse ROS levels in female Australian painted dragon lizards ( Ctenophorus pictus) and their offspring using fluorescent probes and flow cytometry. Basal level of four ROS species (singlet oxygen, peroxynitrite, superoxide and H2O2) measured with a combined marker, and superoxide measured specifically, varied significantly among families but not between the sexes. When blood cells from offspring were chemically encouraged to accelerate the electron transport chain by mitochondrial uncoupling, net superoxide levels were three times higher in daughters than sons (resulting in levels outside of the normal ROS range) and varied among mothers depending on offspring sex (significant interaction between maternal identity and offspring sex). In offspring, there were depressive effects on ROS of size-controlled relative clutch size, which relies directly on circulating levels of vitellogenin, a confirmed antioxidant in some species. Thus, levels of reactive oxygen species varies among females, offspring and in relation to reproductive investment in a manner that makes its regulatory processes likely targets of selection.
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The role of oxygen-increased respirator in humans ascending to high altitude
Directory of Open Access Journals (Sweden)
Shen Guanghao
2012-08-01
Full Text Available Abstract Background Acute mountain sickness (AMS is common for people who live in low altitude areas ascending to the high altitude. Many instruments have been developed to treat mild cases of AMS. However, long-lasting and portable anti-hypoxia equipment for individual is not yet available. Methods Oxygen-increased respirator (OIR has been designed to reduce the risk of acute mountain sickness in acute exposure to low air pressure. It can increase the density of oxygen by increasing total atmospheric pressure in a mask. Male subjects were screened, and eighty-eight were qualified to perform the experiments. The subjects were divided into 5 groups and were involved in some of the tests at 4 different altitudes (Group 1, 2: 3700 m; Group 3,4,5: 4000 m, 4700 m, 5380 m with and without OIR. These tests include heart rate, saturation of peripheral oxygen (SpO2, malondialdehyde (MDA, superoxide dismutase (SOD, blood lactate (BLA and PWC (physical work capacity -170. Results The results showed that higher SpO2, lower heart rate (except during exercise and better recovery of heart rate were observed from all the subjects ’with OIR’ compared with ’without OIR’ (P Conclusions We suggested that OIR may play a useful role in protecting people ascending to high altitude before acclimatization.
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High speed diagnostics for characterization of oxygen / hydrogen rocket injector flowfields
Locke, Justin M.
Temporally-resolved diagnostics are needed to characterize the highly-turbulent flowfields of rocket engine combustors. Two different high speed diagnostic techniques have been applied successfully to study the combustion and mixing characteristics of single-element shear-coaxial injector flowfield in a rocket combustor. Tunable diode laser absorption spectroscopy (TDLAS) is applied to make in-situ measurements with combusting gas-gas propellants, and high speed imaging incorporating backlighting is applied to combusting and non-combusting liquid-gas and gas-gas propellants. Tunable diode laser absorption spectroscopy has been used to make path-integrated temperature and H2O mole fraction measurements in a gaseous oxygen / gaseous hydrogen uni-element rocket chamber with hot background flow. Four mixture conditions were studied at a nominal chamber pressure of 115 psia. Near infrared diode lasers were utilized to target rovibrational transitions of water vapor, which is created through the combustion processes. Both direct absorption spectroscopy and wavelength modulation spectroscopy with second harmonic normalized by first harmonic (1f-normalized WMS-2 f) techniques were applied, with the harmonic detection technique found to yield the best results. Centerline measurements were made at two axial locations, in the near-injector region and far-field region further downstream. Time-resolved measurements of temperature and H2O mole fraction in the rocket chamber are presented. The TDLAS measurements shows clear differences between the near-injector and downstream measurement locations. Mean path-integrated temperatures and H2O mole fractions in the near-injector region are lower than the downstream measurement location. Fluctuations in path-integrated temperature and H2O mole fraction in the downstream location are significantly greater than the near-injector region. This suggests increased turbulence and larger-scale mixing processes are occurring in the downstream
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Directory of Open Access Journals (Sweden)
Can Konca
2018-05-01
Full Text Available Background: Staple-line leak is the most frightening complication of laparoscopic sleeve gastrectomy and several predisposing factors such as using improper staple sizes regardless of gastric wall thickness, narrower bougie diameter and ischemia of the staple line are asserted. Aims: To evaluate the effects of different bougie diameters on tissue oxygen partial pressure at the esophagogastric junction after sleeve gastrectomy. Study Design: A randomized and controlled animal experiment with 1:1:1:1 allocation ratio. Methods: Thirty-two male Wistar Albino rats were randomly divided into 4 groups of 8 each. While 12-Fr bougies were used in groups 1 and 3, 8-Fr bougies were used in groups 2 and 4. Fibrin sealant application was also carried out around the gastrectomy line after sleeve gastrectomy in groups 3 and 4. Burst pressure of gastrectomy line, tissue oxygen partial pressure and hydroxyproline levels at the esophagogastric junction were measured and compared among groups. Results: Mortality was detected in 2 out of 32 rats (6.25% and one of them was in group 2 and the cause of this mortality was gastric leak. Gastric leak was detected in 2 out of 32 rats (6.25%. There was no significant difference in terms of burst pressures, tissue oxygen partial pressure and tissue hydroxyproline levels among the 4 groups. Conclusion: The use of narrower bougie along with fibrin sealant has not had a negative effect on tissue perfusion and wound healing.
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Su, Liwei; Xu, Yawei; Xie, Jian; Wang, Lianbang; Wang, Yuanhao
2016-12-28
The challenging problems of SnO 2 anode material for lithium ion batteries are the poor electronic conductivity and the low oxygen reutilization due to the irreversibility of Li 2 O generated in the initial discharge leading to a theoretical initial Coulombic efficiency (ICE) of only 52.4%. Different from these strategies, this work proposes a novel strategy to level up the oxygen reutilization in SnO 2 by introducing Co 3 Sn 2 nanoalloys which can release Co atoms to reversibly react with Li 2 O instead. According to this protocol, multi-yolk-shell SnO 2 /Co 3 Sn 2 @C nanocubes are designed and successfully prepared using hollow CoSn(OH) 6 nanocubes as precursors followed a hydrothermal carbon coating and calcination treatment. The unique multi-yolk-shell nanostructure offers adequate breathing space for the volumetric deformation during long-term cycling. Moreover, the removal of Li 2 O allows a high electronic conductivity and resultant rate performance. As a result, the efficient reutilization of oxygen enables a high ICE of 71.7% and a reversible capacity of 1003 mA h g -1 after 200 cycles at 100 mA g -1 . Cyclic voltammetry, cycling performance at different voltage windows, and X-ray photoelectron spectroscopy confirm the proposed mechanism. This strategy employing oxygen-poor metals or alloys provides a novel approach to enhance the oxygen reutilization in SnO 2 for higher reversibility.
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Kiko, Rainer; Hauss, Helena; Buchholz, Friedrich; Melzner, Frank
2016-04-01
E. gibboides (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4; E. mucronata not tested). Exposure to differing carbon dioxide levels had no overall significant impact on the respiration or excretion rates. Species from the ETNA were less tolerant to low oxygen levels than E. mucronata from the ETSP, which survived exposure to anoxia at 13 °C. Respiration and excretion rates were reduced upon exposure to low oxygen levels, albeit at different species-specific levels. Reduction of the excretion and respiration rates in ETNA species occurred at a pO2 of 0.6 (P. abdominalis) and 2.4 kPa (U. vulgaris and E. gibboides) at OMZ temperatures. Such low oxygen levels are normally not encountered by these species in the ETNA. E. mucronata however regularly migrates into the strongly hypoxic to anoxic core of the ETSP OMZ. Exposure to low oxygen levels led to a strong reduction of respiration and ammonium excretion in E. mucronata (pcrit respiration = 0.6, pcrit NH4-excretion = 0.73). A drastic reduction of respiratory activity was also observed by other authors for euphausiids, squat lobsters and calanoid copepods, but was not yet accounted for when calculating DVM-mediated active fluxes into the ETSP OMZ. Current estimates of DVM-mediated active export of carbon and nitrogen into the ETSP OMZ are therefore likely too high and future efforts to calculate these export rates should take the physiological responses of migratory species to OMZ conditions into account.
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Dalsgaard, Tage; Stewart, Frank J.; Thamdrup, Bo; De Brabandere, Loreto; Revsbech, Niels Peter; Ulloa, Osvaldo; Canfield, Don E.; DeLong, Edward
2014-01-01
A major percentage (20 to 40%) of global marine fixed-nitrogen loss occurs in oxygen minimum zones (OMZs). Concentrations of O[subscript 2] and the sensitivity of the anaerobic N[subscript 2]-producing processes of anammox and denitrification determine where this loss occurs. We studied experimentally how O[subscript 2] at nanomolar levels affects anammox and denitrification rates and the transcription of nitrogen cycle genes in the anoxic OMZ off Chile. Rates of anammox and denitrification w...
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Modification of radiation sensitivity: the oxygen effect
International Nuclear Information System (INIS)
Quintiliani, M.
1979-01-01
Four fundamental aspects of the oxygen effect in radiobiology are reviewed, with emphasis on single cell systems: (1) Radiosensitivity in relation to oxygen concentration. In many biological systems, this relationship is remarkably well represented by the well-known Howard-Flanders/Alper formula. Often, however, the degree of uncertainty associated with the estimation of the value of K in the formula is fairly high. Recent data on V79-753B cells indicate a biphasic influence of oxygen concentration on radiosensitivity that cannot be described in terms of the Howard-Flanders/Alper model. (2) The oxygen effect in relation to survival level. The influence of very low oxygen concentrations on the shoulder of the survival curves of irradiated cells is still controversial. Also, the oxygen dependence of repair processes for sublethal and potentially lethal damage need to be better defined. (3) Time-scale of the oxygen effect. All the experimental data obtained with the use of fast techniques indicate that the time scale of the oxygen effect is consistent with that of free radical reactions. This appears to be compatible with the hypothesis that oxygen acts by fixation of a radiation-induced reversible damage. The existence of two types of damage with different rates of decay is suggested, both in bacterial and mammalian cells. (4) Molecular mechanisms of the oxygen effect. In spite of the very large literature on this subject, the identification of the detailed molecular mechanisms of the oxygen effect must still be considered goals for future research
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Zolpidem reduces the blood oxygen level-dependent signal during visual system stimulation.
Licata, Stephanie C; Lowen, Steven B; Trksak, George H; Maclean, Robert R; Lukas, Scott E
2011-08-15
Zolpidem is a short-acting imidazopyridine hypnotic that binds at the benzodiazepine binding site on specific GABA(A) receptors to enhance fast inhibitory neurotransmission. The behavioral and receptor pharmacology of zolpidem has been studied extensively, but little is known about its neuronal substrates in vivo. In the present within-subject, double-blind, and placebo-controlled study, blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) at 3 Tesla was used to assess the effects of zolpidem within the brain. Healthy participants (n=12) were scanned 60 min after acute oral administration of zolpidem (0, 5, 10, or 20mg), and changes in BOLD signal were measured in the visual cortex during presentation of a flashing checkerboard. Heart rate and oxygen saturation were monitored continuously throughout the session. Zolpidem (10 and 20mg) reduced the robust visual system activation produced by presentation of this stimulus, but had no effects on physiological activity during the fMRI scan. Zolpidem's modulation of the BOLD signal within the visual cortex is consistent with the abundant distribution of GABA(A) receptors localized in this region, as well as previous studies showing a relationship between increased GABA-mediated neuronal inhibition and a reduction in BOLD activation. Copyright © 2011 Elsevier Inc. All rights reserved.
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Zolpidem reduces the blood oxygen level-dependent signal during visual system stimulation
Licata, Stephanie C.; Lowen, Steven B.; Trksak, George H.; MacLean, Robert R.; Lukas, Scott E.
2011-01-01
Zolpidem is a short-acting imidazopyridine hypnotic that binds at the benzodiazepine binding site on specific GABAA receptors to enhance fast inhibitory neurotransmission. The behavioral and receptor pharmacology of zolpidem has been studied extensively, but little is known about its neuronal substrates in vivo. In the present within-subject, double-blind, and placebo-controlled study, blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) at 3 Tesla was used to assess the effects of zolpidem within the brain. Healthy participants (n=12) were scanned 60 minutes after acute oral administration of zolpidem (0, 5, 10, or 20 mg), and changes in BOLD signal were measured in the visual cortex during presentation of a flashing checkerboard. Heart rate and oxygen saturation were monitored continuously throughout the session. Zolpidem (10 and 20 mg) reduced the robust visual system activation produced by presentation of this stimulus, but had no effects on physiological activity during the fMRI scan. Zolpidem’s modulation of the BOLD signal within the visual cortex is consistent with the abundant distribution of GABAA receptors localized in this region, as well as previous studies showing a relationship between increased GABA-mediated neuronal inhibition and a reduction in BOLD activation. PMID:21640782
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Development of an oxygen carrier nanoemulsion for organ preservation
CSIR Research Space (South Africa)
Barnard, A
2010-08-31
Full Text Available high levels of chemical stability and biological inertness which makes them suitable for biological use1,2. Perfluorooctyl bromide (PFOB) is the particular PFC used in the CSIR oxygen carrier emulsion1,2....
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Yang, Wenmin; Hong, Jie; Zeng, Qiyi; Tao, Jianping; Chen, Feiyan; Dang, Run; Liang, Yufeng; Wu, Zhiyuan; Yang, Yiyu
2016-01-01
The efficacy and therapeutic mechanisms of continuous renal replacement therapy (CRRT) for improvement of oxygenation in acute respiratory distress syndrome (ARDS) remain controversial. These questions were addressed by retrospective analysis of severe ARDS patients admitted to the pediatric intensive care unit of our hospital from 2009 to 2015 who received high-volume continuous veno-venous hemofiltration during mechanical ventilation. There was a significant improvement in partial oxygen pressure/fraction of inspired oxygen (PaO2/FiO2) 24 hours after CRRT onset compared with baseline (median change = 51.5; range = -19 to 450.5; P Improvement in oxygenation is likely related to both restoration of fluid balance and clearance of inflammatory mediators.
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Oxygen doping of the high T/sub c/ superconducting perovskites
International Nuclear Information System (INIS)
Tarascon, J.M.; McKinnon, W.R.; Greene, L.H.; Hull, G.W.; Bagley, B.G.; Vogel, E.M.; Le Page, Y.
1987-01-01
Oxygen defect perovskites are studied because of their ability to reversibly intercalate oxygen atoms. Our previous studies of the La/sub 2-y/Sr/sub y/CuO/sub 4-x/ system shows that T/sub c/ is dramatically affected by subtle changes in oxygen content. However since this study did not achieve large values of x, a systematic study was not undertaken. The authors have found by thermogravimetric analysis (TGA) that a wide range of oxygen non-stoichiometry in the 90K superconductor YBa/sub 2/Cu/sub 3/O/sub 7-x/ is obtainable. This study of the effect of oxygen doping on the transport properties of the 40K material, and a systematic analysis of this over a broader range in the 90K superconductor is presented
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Investigation on the improved radiation hardness of silicon detectors with high oxygen concentration
International Nuclear Information System (INIS)
Moll, M.; Fretwurst, E.; Lindstroem, G.
2000-01-01
We present an investigation on the influence of the oxygen concentration on radiation-induced changes in the effective doping concentration of silicon detectors. Diodes fabricated from silicon with interstitial oxygen content ranging from below 2x10 14 to 9x10 17 cm -3 have been irradiated with fast neutrons up to a fluence of 2x10 15 cm -2 . Our main interest focused on the so-called stable damage component in the change of the effective doping concentration being of prime importance for the application of silicon detectors in high-energy physics experiments. We demonstrate, that with a high oxygen enrichment the donor removal is appreciably reduced, reaching a value of only 10% of the initial doping concentration for [O i ]=9x10 17 cm -3 , while for normal detector grade material with [O i ] below 5x10 16 cm -3 that value is 60-90%. Furthermore, we show that the fluence proportional introduction of stable acceptors is independent of the oxygen concentration with an averaged introduction rate of (1.49±0.03)x10 -2 cm -1 . Only one material was found exhibiting a significantly smaller value of about 0.6x10 -2 cm -1 and thus indicating the possibility to suppress the radiation-induced acceptor creation by material modification. Finally, we show that the experimental findings disagree in several important aspects with predictions made by microscopic defect kinetics models, leaving the physical background of some of the measured data as an open question
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Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy
International Nuclear Information System (INIS)
Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V.
2001-01-01
The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E c ) and at 415 K (0.9 below E c ); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E c known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E c is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species
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Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy
Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S. V.
2001-10-01
The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below Ec) and at 415 K (0.9 below Ec); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below Ec known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below Ec is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species.
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Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy
International Nuclear Information System (INIS)
Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V.
2004-01-01
The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E c ) and at 415 K (0.9 below E c ); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E c known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E c is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species. (author)
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Biogeochemical Modeling of the Second Rise of Oxygen
Smith, M. L.; Catling, D.; Claire, M.; Zahnle, K.
2014-03-01
The rise of atmospheric oxygen set the tempo for the evolution of complex life on Earth. Oxygen levels are thought to have increased in two broad steps: one step occurred in the Archean ~ 2.45 Ga (the Great Oxidation Event or GOE), and another step occured in the Neoproterozoic ~750-580 Ma (the Neoprotoerozoic Oxygenation Event or NOE). During the NOE, oxygen levels increased from ~1-10% of the present atmospheric level (PAL) (Holland, 2006), to ~15% PAL in the late Neoproterozoic, to ~100% PAL later in the Phanerozoic. Complex life requires O2, so this transition allowed complex life to evolve. We seek to understand what caused the NOE. To explore causes for the NOE, we build upon the biogeochemical model of Claire et al. (2006), which calculates the redox evolution of the atmosphere, ocean, biosphere, and crust in the Archean through to the early Proterozoic. In this model, the balance between oxygenconsuming and oyxgen-producing fluxes evolves over time such that at ~2.4 Ga, the rapidly acting sources of oxygen outweigh the rapidly-acting sinks. Or, in other words, at ~2.4 Ga, the flux of oxygen from organic carbon burial exceeds the sinks of oxygen from reaction with reduced volcanic and metamoprphic gases. The model is able to drive oxygen levels to 1-10% PAL in the Proterozoic; however, the evolving redox fluxes in the model cannot explain how oxygen levels pushed above 1-10% in the late Proterozoic. The authors suggest that perhaps another buffer, such as sulfur, is needed to describe Proterozoic and Phanerozoic redox evolution. Geologic proxies show that in the Proterozoic, up to 10% of the deep ocean may have been sulfidic. With this ocean chemistry, the global sulfur cycle would have worked differently than it does today. Because the sulfur and oxygen cycles interact, the oxygen concentration could have permanently changed due to an evolving sulfur cycle (in combination with evolving redox fluxes associated with other parts of the oxygen cycle and carbon
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Directory of Open Access Journals (Sweden)
Bill R. Christian
2018-02-01
Full Text Available Patients requiring emergency airway management may be at greater risk of acute hypoxemic events because of underlying lung pathology, high metabolic demands, insufficient respiratory drive, obesity, or the inability to protect their airway against aspiration. Emergency tracheal intubation is often required before complete information needed to assess the risk of procedural hypoxia is acquired (i.e., arterial blood gas level, hemoglobin value, or chest radiograph. During pre-oxygenation, administering high-flow nasal oxygen in addition to a non-rebreather face mask can significantly boost the effective inspired oxygen. Similarly, with the apnea created by rapid sequence intubation (RSI procedures, the same high-flow nasal cannula can help maintain or increase oxygen saturation during efforts to secure the tube (oral intubation. Thus, the use of nasal oxygen during pre-oxygenation and continued during apnea can prevent hypoxia before and during intubation, extending safe apnea time, and improve first-pass success attempts. We conducted a literature review of nasal-cannula apneic oxygenation during intubation, focusing on two components: oxygen saturation during intubation, and oxygen desaturation time. We performed an electronic literature search from 1980 to November 2017, using PubMed, Elsevier, ScienceDirect, and EBSCO. We identified 14 studies that pointed toward the benefits of using nasal cannula during emergency intubation.
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High energy-intensity atomic oxygen beam source for low earth orbit materials degradation studies
International Nuclear Information System (INIS)
Cross, J.B.; Blais, N.C.
1988-01-01
A high intensity (10 19 O-atoms/s-sr) high energy (5 eV) source of oxygen atoms has been developed that produces a total fluence of 10 22 O-atoms/cm 2 in less than 100 hours of continuous operation at a distance of 15 cm from the source. The source employs a CW CO 2 laser sustained discharge to form a high temperature (15,000 K) plasma in the throat of a 0.3-mm diameter nozzle using 3--8 atmospheres of rare gas/O 2 mixtures. Visible and infrared photon flux levels of 1 watt/cm 2 have been measured 15 cm downstream of the source while vacuum UV (VUV) fluxes are comparable to that measured in low earth orbit. The reactions of atomic oxygen with kapton, Teflon, silver, and various coatings have been studied. The oxidation of kapton (reaction efficiency = 3 /times/ 10/sup /minus/24/ cm /+-/ 50%) has an activation energy of 0.8 Kcal/mole over the temperature range of 25/degree/C to 100/degree/C at a beam energy of 1.5 eV and produces low molecular weight gas phase reaction products (H 2 O, NO, CO 2 ). Teflon reacts with ∼0.1--0.2 efficiency to that of kapton at 25/degree/C and both surfaces show a rug-like texture after exposure to the O-atom beam. Angular scattering distribution measurements of O-atoms show a near cosine distribution from reactive surfaces indicating complete accommodation of the translational energy with the surface while a nonreactive surface (nickel oxide) shows specular-like scattering with 50% accommodation of the translational energy with the surface. A technique for simple on orbit chemical experiments using resistance measurements of coated silver strips is described. 9 figs
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Zheng, Yao
2017-02-21
Organometallic complexes with metal-nitrogen/carbon (M-N/C) coordination are the most important alternatives to precious metal catalysts for oxygen reduction and evolution reactions (ORR and OER) in energy conversion devices. Here, we designed and developed a range of molecule-level graphitic carbon nitride (g-C3N4) coordinated transition metals (M-C3N4) as a new generation of M-N/C catalysts for these oxygen electrode reactions. As a proof-of-concept example, we conducted theoretical evaluation and experimental validation on a cobalt-C3N4 catalyst with a desired molecular configuration, which possesses comparable electrocatalytic activity to that of precious metal benchmarks for the ORR and OER in alkaline media. The correlation of experimental and computational results confirms that this high activity originates from the precise M-N2 coordination in the g-C3N4 matrix. Moreover, the reversible ORR/OER activity trend for a wide variety of M-C3N4 complexes has been constructed to provide guidance for the molecular design of this promising class of catalysts.
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Pinning by oxygen vacancies in high-Tc superconductors
International Nuclear Information System (INIS)
Chudnovsky, E.M.
1990-01-01
It is shown that recent data of Murray et al. on spatial correlations in flux lattices of Bi-Sr-Ca-Cu-O (BSCCO) may be explained if one assumes that 1% of oxygen atoms in CuO 2 layers are missing. This estimate, being in remarkable agreement with that deduced by Kes and van der Beek from ac-susceptibility measurements, provides strong confidence that oxygen vacancies are the major source of pinning in BSCCO
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Sterilization by pure oxygen plasma and by oxygen-hydrogen peroxide plasma: an efficacy study.
Boscariol, M R; Moreira, A J; Mansano, R D; Kikuchi, I S; Pinto, T J A
2008-04-02
Plasma is an innovative sterilization method characterized by a low toxicity to operators and patients, and also by its operation at temperatures close to room temperatures. The use of different parameters for this method of sterilization and the corresponding results were analyzed in this study. A low-pressure inductive discharge was used to study the plasma sterilization processes. Oxygen and a mixture of oxygen and hydrogen peroxide were used as plasma source gases. The efficacy of the processes using different combinations of parameters such as plasma-generation method, type of gas, pressure, gas flow rate, temperature, power, and exposure time was evaluated. Two phases were developed for the processes, one using pure oxygen and the other a mixture of gases. Bacillus subtilis var. niger ATCC 9372 (Bacillus atrophaeus) spores inoculated on glass coverslips were used as biological indicators to evaluate the efficacy of the processes. All cycles were carried out in triplicate for different sublethal exposure times to calculate the D value by the enumeration method. The pour-plate technique was used to quantify the spores. D values of between 8 and 3 min were obtained. Best results were achieved at high power levels (350 and 400 W) using pure oxygen, showing that plasma sterilization is a promising alternative to other sterilization methods.
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Low oxygen levels slow embryonic development of Limulus polyphemus
DEFF Research Database (Denmark)
Funch, Peter; Wang, Tobias; Pertoldi, Cino
2016-01-01
The American horseshoe crab Limulus polyphemus typically spawns in the upper intertidal zone, where the developing embryos are exposed to large variations in abiotic factors such as temperature, humidity, salinity, and oxygen, which affect the rate of development. It has been shown that embryonic...... pronounced hypoxia in later embryonic developmental stages, but also in earlier, previously unexplored, developmental stages....... development is slowed at both high and low salinities and temperatures, and that late embryos close to hatching tolerate periodic hypoxia. In this study we investigated the influence of hypoxia on both early and late embryonic development in L. polyphemus under controlled laboratory conditions. Embryos were...
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High-affinity hemoglobin and blood oxygen saturation in diving emperor penguins.
Meir, Jessica U; Ponganis, Paul J
2009-10-01
The emperor penguin (Aptenodytes forsteri) thrives in the Antarctic underwater environment, diving to depths greater than 500 m and for durations longer than 23 min. To examine mechanisms underlying the exceptional diving ability of this species and further describe blood oxygen (O2) transport and depletion while diving, we characterized the O2-hemoglobin (Hb) dissociation curve of the emperor penguin in whole blood. This allowed us to (1) investigate the biochemical adaptation of Hb in this species, and (2) address blood O2 depletion during diving, by applying the dissociation curve to previously collected partial pressure of O2 (PO2) profiles to estimate in vivo Hb saturation (SO2) changes during dives. This investigation revealed enhanced Hb-O2 affinity (P50=28 mmHg, pH 7.5) in the emperor penguin, similar to high-altitude birds and other penguin species. This allows for increased O2 at low blood PO2 levels during diving and more complete depletion of the respiratory O2 store. SO2 profiles during diving demonstrated that arterial SO2 levels are maintained near 100% throughout much of the dive, not decreasing significantly until the final ascent phase. End-of-dive venous SO2 values were widely distributed and optimization of the venous blood O2 store resulted from arterialization and near complete depletion of venous blood O2 during longer dives. The estimated contribution of the blood O2 store to diving metabolic rate was low and highly variable. This pattern is due, in part, to the influx of O2 from the lungs into the blood during diving, and variable rates of tissue O2 uptake.
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Sub-sets of cancer stem cells differ intrinsically in their patterns of oxygen metabolism.
Directory of Open Access Journals (Sweden)
Luke Gammon
Full Text Available The glycolytic response of hypoxic cells is primarily mediated by the hypoxia inducible factor alpha (HIF-1α but even in the presence of abundant oxygen tumours typically show high rates of glycolysis. Higher levels of HIF-1α in tumours are associated with a poorer prognosis and up-regulation of markers of epithelial mesenchymal transition (EMT due to HIF-1α actions. We have recently shown that EMT occurs within the CD44(high cancer stem cell (CSC fraction and that epithelial and EMT CSCs are distinguished by high and low ESA expression, respectively. We here show that hypoxia induces a marked shift of the CSC fraction towards EMT leading to altered cell morphology, an increased proportion of CD44(high/ESA(low cells, patterns of gene expression typical of EMT, and enhanced sphere-forming ability. The size of EMT fractions returned to control levels in normoxia indicating a reversible process. Surprisingly, however, even under normoxic conditions a fraction of EMT CSCs was present and maintained high levels of HIF-1α, apparently due to actions of cytokines such as TNFα. Functionally, this EMT CSC fraction showed decreased mitochondrial mass and membrane potential, consumed far less oxygen per cell, and produced markedly reduced levels of reactive oxygen species (ROS. These differences in the patterns of oxygen metabolism of sub-fractions of tumour cells provide an explanation for the general therapeutic resistance of CSCs and for the even greater resistance of EMT CSCs. They also identify potential mechanisms for manipulation of CSCs.
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Directory of Open Access Journals (Sweden)
D'Souza Olympio
2010-02-01
Full Text Available Abstract Introduction Cerebral misery perfusion represents a failure of cerebral autoregulation. It is an important differential diagnosis in post-stroke patients presenting with collapses in the presence of haemodynamically significant cerebrovascular stenosis. This is particularly the case when cortical or internal watershed infarcts are present. When this condition occurs, further investigation should be done immediately. Case presentation A 50-year-old Caucasian man presented with a stroke secondary to complete occlusion of his left internal carotid artery. He went on to suffer recurrent seizures. Neuroimaging demonstrated numerous new watershed-territory cerebral infarcts. No source of arterial thromboembolism was demonstrable. Hypercapnic blood-oxygenation-level-dependent-contrast functional magnetic resonance imaging was used to measure his cerebrovascular reserve capacity. The findings were suggestive of cerebral misery perfusion. Conclusions Blood-oxygenation-level-dependent-contrast functional magnetic resonance imaging allows the inference of cerebral misery perfusion. This procedure is cheaper and more readily available than positron emission tomography imaging, which is the current gold standard diagnostic test. The most evaluated treatment for cerebral misery perfusion is extracranial-intracranial bypass. Although previous trials of this have been unfavourable, the results of new studies involving extracranial-intracranial bypass in high-risk patients identified during cerebral perfusion imaging are awaited. Cerebral misery perfusion is an important and under-recognized condition in which emerging imaging and treatment modalities present the possibility of practical and evidence-based management in the near future. Physicians should thus be aware of this disorder and of recent developments in diagnostic tests that allow its detection.
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Non-self-sustained electric discharge in oxygen gas mixtures: singlet delta oxygen production
Ionin, A A; Kotkov, A A; Kochetov, I V; Napartovich, A P; Seleznev, L V; Sinitsyn, D V; Hager, G D
2003-01-01
The possibility of obtaining a high specific input energy in an electron-beam sustained discharge ignited in oxygen gas mixtures O sub 2 : Ar : CO (or H sub 2) at the total gas pressures of 10-100 Torr was experimentally demonstrated. The specific input energy per molecular component exceeded approx 6 kJ l sup - sup 1 atm sup - sup 1 (150 kJ mol sup - sup 1) as a small amount of carbon monoxide was added into a gas mixture of oxygen and argon. It was theoretically demonstrated that one might expect to obtain a singlet delta oxygen yield of 25% exceeding its threshold value needed for an oxygen-iodine laser operation at room temperature, when maintaining a non-self-sustained discharge in oxygen gas mixtures with molecular additives CO, H sub 2 or D sub 2. The efficiency of singlet delta oxygen production can be as high as 40%.
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Influence of oxygen at high pressure on the induction of damage in barley seeds by gamma radiation
International Nuclear Information System (INIS)
Donaldson, E.; Nilan, R.A.; Konzak, C.F.
1978-01-01
The influence of oxygen pressure prior to, during, and after irradiation on the induction of radiation damage was investigated using Himalaya (C.I. 620) barley seeds. Seeds were adjusted to water contents of 2 to 14% and then irradiated with 60 Co gamma rays in vacuo or under various oxygen tensions. After irradiation, the seeds were rehydrated at approximately 0 0 C in water continuously bubbled with oxygen or nitrogen. Biological effects of the treatments were recorded as M 1 seedling injury. Seeds irradiated in oxygen pressure sustained two or three times more damage than those irradiated in vacuo followed by rehydrating in oxygenated water. Greater damage occurred when seeds were (a) exposed to oxygen pressure and the pressure released before irradiation, (b) irradiated under oxygen pressure, or (c) irradiated in vacuo and then exposed to oxygen pressure than when irradiated in vacuo and rehydrated in oxygenated water. These results suggest that seeds can be saturated with oxygen before irradiation and also that the radiation-induced sites (presumably free radicals) which react with the oxygen are somewhat stable in very dry seeds. That the reaction probably occurs before the seeds are rehydrated was demonstrated by the failure to remove the effect of oxygen pressure between high oxygen pressure treatment and irradiation. The results indicate that placing the seeds under oxygen pressure may increase the rate and extent of the reactions occurring during post-radiation storage of seeds in the presence of oxygen. The increase in damage associated with aerobic rehydration is partially lost during aerobic storage and is largely pre-empted when seeds are placed under oxygen pressure. The decrease in damage associated with aerobic rehydration is accompanied by an increase in damage occurring with anaerobic rehydration, suggesting that the reaction which leads to damage was initiated before rehydration and to the same oxygen sensitive sites
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Energy Technology Data Exchange (ETDEWEB)
Gersing, Alexandra S.; Schwaiger, Benedikt J. [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); University of California, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Ankenbrank, Monika; Toth, Vivien; Bauer, Jan S.; Zimmer, Claus [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); Janssen, Insa [Technical University Munich, Department of Neurosurgery, Munich (Germany); Kooijman, Hendrik [Philips Healthcare, Hamburg (Germany); Wunderlich, Silke [Technical University Munich, Department of Neurology, Munich (Germany); Preibisch, Christine [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); Technical University Munich, Department of Neurology, Munich (Germany)
2015-12-15
MR-derived cerebral metabolic rate of oxygen utilization (CMRO{sub 2}) has been suggested to be analogous to PET-derived CMRO{sub 2} and therefore may be used for detection of viable tissue at risk for infarction. The purpose of this study was to evaluate MR-derived CMRO{sub 2} mapping in acute ischemic stroke in relation to established diffusion- and perfusion-weighted imaging. In 23 patients (mean age 63 ± 18.7 years, 11 women) with imaging findings for acute ischemic stroke, relative oxygen extraction fraction was calculated from quantitative transverse relaxation times (T2, T2*) and relative cerebral blood volume using a quantitative blood oxygenation level dependent (BOLD) approach in order to detect a local increase of deoxyhemoglobin. Relative CMRO{sub 2} (rCMRO{sub 2}) maps were calculated by multiplying relative oxygen extraction fraction (rOEF) by cerebral blood flow, derived from PWI. After co-registration, rCMRO{sub 2} maps were evaluated in comparison with apparent diffusion coefficient (ADC) and time-to-peak (TTP) maps. Mean rCMRO{sub 2} values in areas with diffusion-restriction or TTP/ADC mismatch were compared with rCMRO{sub 2} values in the contralateral tissue. In tissue with diffusion restriction, mean rCMRO{sub 2} values were significantly decreased compared to perfusion-impaired (17.9 [95 % confidence interval 10.3, 25.0] vs. 58.1 [95 % confidence interval 50.1, 70.3]; P < 0.001) and tissue in the contralateral hemisphere (68.2 [95 % confidence interval 61.4, 75.0]; P < 0.001). rCMRO{sub 2} in perfusion-impaired tissue showed no significant change compared to tissue in the contralateral hemisphere (58.1 [95 % confidence interval 50.1, 70.3] vs. 66.7 [95 % confidence interval 53.4, 73.4]; P = 0.34). MR-derived CMRO{sub 2} was decreased within diffusion-restricted tissue and stable within perfusion-impaired tissue, suggesting that this technique may be adequate to reveal different pathophysiological stages in acute stroke. (orig.)
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Highly Graphitic Carbon Nanofibers Web as a Cathode Material for Lithium Oxygen Batteries
Directory of Open Access Journals (Sweden)
Hyungkyu Han
2018-01-01
Full Text Available The lithium oxygen battery is a promising energy storage system due to its high theoretical energy density and ability to use oxygen from air as a “fuel”. Although various carbonaceous materials have been widely used as a cathode material due to their high electronic conductivity and facial processability, previous studies mainly focused on the electrochemical properties associated with the materials (such as graphene and carbon nanotubes and the electrode configuration. Recent reports demonstrated that the polarization associated with cycling could be significantly increased by lithium carbonates generated from the reaction between the carbon cathode and an electrolyte, which indicates that the physicochemical properties of the carbon cathode could play an important role on the electrochemical performances. However, there is no systematic study to understand these phenomena. Here, we systematically explore the electrochemical properties of carbon nanofibers (CNF webs with different graphitization degree as a cathode for Li oxygen batteries. The physicochemical properties and electrochemical properties of CNF webs were carefully monitored before and after cycling. CNF webs are prepared at 1000, 1200 and 1400 °C. CNF web pyrolyzed at 1400 °C shows lowered polarization and improved cycle retention compared to those of CNF webs pyrolyzed at 1000 and 1200 °C.
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The oxic degradation of sedimentary organic matter 1400 Ma constrains atmospheric oxygen levels
DEFF Research Database (Denmark)
Zhang, Shuichang; Wang, Xiaomei; Wang, Huajian
2017-01-01
shales are enriched in redox-sensitive trace metals, have high concentrations of total organic carbon (TOC), high hydrogen index (HI) and iron speciation indicating deposition under anoxic conditions. In contrast, the green-gray shales show no trace metal enrichments, have low TOC, low HI and iron...... speciation consistent with an oxygenated depositional setting. Altogether, unit 1 displays alternations between oxic and anoxic depositional environments, driving differences in carbon preservation consistent with observations from the modern ocean. We combined our TOC and HI results to calculate...
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High-level fluorescence labeling of gram-positive pathogens.
Directory of Open Access Journals (Sweden)
Simone Aymanns
Full Text Available Fluorescence labeling of bacterial pathogens has a broad range of interesting applications including the observation of living bacteria within host cells. We constructed a novel vector based on the E. coli streptococcal shuttle plasmid pAT28 that can propagate in numerous bacterial species from different genera. The plasmid harbors a promoterless copy of the green fluorescent variant gene egfp under the control of the CAMP-factor gene (cfb promoter of Streptococcus agalactiae and was designated pBSU101. Upon transfer of the plasmid into streptococci, the bacteria show a distinct and easily detectable fluorescence using a standard fluorescence microscope and quantification by FACS-analysis demonstrated values that were 10-50 times increased over the respective controls. To assess the suitability of the construct for high efficiency fluorescence labeling in different gram-positive pathogens, numerous species were transformed. We successfully labeled Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus dysgalactiae subsp. equisimilis, Enterococcus faecalis, Enterococcus faecium, Streptococcus mutans, Streptococcus anginosus and Staphylococcus aureus strains utilizing the EGFP reporter plasmid pBSU101. In all of these species the presence of the cfb promoter construct resulted in high-level EGFP expression that could be further increased by growing the streptococcal and enterococcal cultures under high oxygen conditions through continuous aeration.
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Macroscopic results for a novel oxygenated silicon material
Watts, S J; Karpenko, A
2002-01-01
High-resistivity FZ silicon diodes have been processed in order to increase their oxygen dimer (O sub 2 sub i) concentration. Deep level transient spectroscopy measurements have been performed after proton irradiation showing that the formation of the VO centre is suppressed. The substrates had a starting resistivity of 2-4 k OMEGA cm, with an oxygen concentration of 10 sup 1 sup 5 and 10 sup 1 sup 7 cm sup - sup 3. Results for doping changes, leakage current and annealing behaviour after irradiation with 24 GeV/c protons are shown.
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Fire feedbacks over geological time and the evolution of atmospheric oxygen concentration
Mills, B.; Belcher, C.; Lenton, T. M.
2017-12-01
During the 4.5 billion year history of the Earth, the concentration of oxygen in the atmosphere has risen from trace levels to today's 21%. Yet over the last 400 million years, O2 concentration appears to have remained within a relatively narrow range (around 15% - 30%), despite dramatic changes in the nature of global biogeochemical cycling. This stability has been crucial for continued animal evolution, and is thought to have arisen through feedbacks between oxygen, wildfire and plant productivity: the strong oxygen- dependence of fire initiation and spread means that global photosynthetic primary productivity is suppressed when oxygen levels are high, and enhanced when levels are low. We present biogeochemical modelling of the long term carbon and oxygen cycles, which aims to capture the operation of the wildfire feedback alongside other key processes. We find that wildfire can effectively stabilize long term oxygen concentrations, but that the nature of this feedback has changed as plant evolution has provided different fuels. Specifically, the evolution of early angiosperms during the Cretaceous period provided new understory fuels that more easily facilitated crown and canopy fires. Adding these dynamics to our model produces a more stable system over long timescales, and the model predicts that oxygen concentration has declined towards the present day - a prediction that is supported by other independent estimates.
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Plant hemoglobins: Important players at the crossroads between oxygen and nitric oxide
DEFF Research Database (Denmark)
Gupta, Kapuganti J; Hebelstrup, Kim; Mur, Luis A J
2011-01-01
Plant hemoglobins constitute a diverse group of hemeproteins and evolutionarily belong to three different classes. Class 1 hemoglobins possess an extremely high affinity to oxygen and their main function consists in scavenging of nitric oxide (NO) at very low oxygen levels. Class 2 hemoglobins have...... at high O2 concentrations. Depending on their physical properties, hemoglobins belong either to hexacoordinate non-symbiotic or pentacoordinate symbiotic groups. Plant hemoglobins are plausible targets for improving resistance to multiple stresses....
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Hempel, Andreas W; O'Sullivan, Maurice G; Papkovsky, Dmitri B; Kerry, Joseph P
2013-05-22
Optical oxygen sensors were used to ascertain the level of oxygen consumed by individual salad leaves for optimised packaging of ready-to-eat (RTE) Italian salad mixes during refrigerated storage. Seven commonly found leaves in Italian salad mixes were individually assessed for oxygen utilisation in packs. Each leaf showed varying levels of respiration throughout storage. Using the information obtained, an experimental salad mix was formulated (termed Mix 3) which consisted of the four slowest respiring salad leaves-Escarole, Frisee, Red Batavia, Lollo Rosso. Mix 3 was then compared against two commercially available Italian salads; Mix 1 (Escarole, Frisee, Radicchio, Lollo Rosso) and Mix 2 (Cos, Frisee, Radicchio, Lollo Rosso). Optical sensors were used to non-destructively monitor oxygen usage in all mixes throughout storage. In addition to oxygen consumption, all three salad mixes were quality assessed in terms of microbial load and sensorial acceptability. In conclusion, Mix 3 was found to consume the least amount of oxygen over time, had the lowest microbial load and was most sensorially preferred ( p products.
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A role for haemolymph oxygen capacity in heat tolerance of eurythermal crabs.
Directory of Open Access Journals (Sweden)
Folco eGiomi
2013-05-01
Full Text Available Heat tolerance in aquatic ectotherms is constrained by a mismatch, occurring at high temperatures, between oxygen delivery and demand which compromises the maintenance of aerobic scope. The present study analyses how the wide thermal tolerance range of an eurythermal model species, the green crab Carcinus maenas is supported and limited by its ability to sustain efficient oxygen transport to tissues. Similar to other eurytherms, C. maenas sustains naturally occurring acute warming events through the integrated response of circulatory and respiratory systems. The response of C. maenas to warming is characterized by two phases. During initial warming, oxygen consumption and heart rate increase while stroke volume and haemolymph oxygen partial pressures decrease. During further warming, dissolved oxygen levels in the venous compartment decrease below the threshold of full haemocyanin oxygen saturation. The progressive release of haemocyanin bound oxygen with further warming follows an exponential pattern, thereby saving energy in oxygen transport and causing an associated leveling off of metabolic rate. According to the concept of oxygen and capacity limited thermal tolerance, this indicates that the thermal tolerance window is widened by the increasing contribution of haemocyanin oxygen transport and associated energy savings in cardiocirculation. Haemocyanin bound oxygen sustains cardiac performance to cover the temperature range experienced by C. maenas in the field. To our knowledge this is the first study providing evidence of a relationship between thermal tolerance and blood (haemolymph oxygen transport in eurythermal invertebrates.
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A role for haemolymph oxygen capacity in heat tolerance of eurythermal crabs.
Giomi, Folco; Pörtner, Hans-Otto
2013-01-01
Heat tolerance in aquatic ectotherms is constrained by a mismatch, occurring at high temperatures, between oxygen delivery and demand which compromises the maintenance of aerobic scope. The present study analyses how the wide thermal tolerance range of an eurythermal model species, the green crab Carcinus maenas is supported and limited by its ability to sustain efficient oxygen transport to tissues. Similar to other eurytherms, C. maenas sustains naturally occurring acute warming events through the integrated response of circulatory and respiratory systems. The response of C. maenas to warming can be characterized by two phases. During initial warming, oxygen consumption and heart rate increase, while stroke volume and haemolymph oxygen partial pressure decrease. During further warming, dissolved oxygen levels in the venous compartment decrease below the threshold of full haemocyanin oxygen saturation. The progressive release of haemocyanin bound oxygen with further warming follows an exponential pattern, thereby saving energy in oxygen transport and causing an associated leveling off of metabolic rate. According to the concept of oxygen and capacity limited thermal tolerance (OCLTT), this indicates that the thermal tolerance window is widened by the increasing contribution of haemocyanin oxygen transport and associated energy savings in cardiocirculation. Haemocyanin bound oxygen sustains cardiac performance to cover the temperature range experienced by C. maenas in the field. To our knowledge this is the first study providing evidence of a relationship between thermal tolerance and blood (haemolymph) oxygen transport in a eurythermal invertebrate.
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Cho, Junghun; Kee, Youngwook; Spincemaille, Pascal; Nguyen, Thanh D; Zhang, Jingwei; Gupta, Ajay; Zhang, Shun; Wang, Yi
2018-03-07
To map the cerebral metabolic rate of oxygen (CMRO 2 ) by estimating the oxygen extraction fraction (OEF) from gradient echo imaging (GRE) using phase and magnitude of the GRE data. 3D multi-echo gradient echo imaging and perfusion imaging with arterial spin labeling were performed in 11 healthy subjects. CMRO 2 and OEF maps were reconstructed by joint quantitative susceptibility mapping (QSM) to process GRE phases and quantitative blood oxygen level-dependent (qBOLD) modeling to process GRE magnitudes. Comparisons with QSM and qBOLD alone were performed using ROI analysis, paired t-tests, and Bland-Altman plot. The average CMRO 2 value in cortical gray matter across subjects were 140.4 ± 14.9, 134.1 ± 12.5, and 184.6 ± 17.9 μmol/100 g/min, with corresponding OEFs of 30.9 ± 3.4%, 30.0 ± 1.8%, and 40.9 ± 2.4% for methods based on QSM, qBOLD, and QSM+qBOLD, respectively. QSM+qBOLD provided the highest CMRO 2 contrast between gray and white matter, more uniform OEF than QSM, and less noisy OEF than qBOLD. Quantitative CMRO 2 mapping that fits the entire complex GRE data is feasible by combining QSM analysis of phase and qBOLD analysis of magnitude. © 2018 International Society for Magnetic Resonance in Medicine.
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Directory of Open Access Journals (Sweden)
Yuetian Yu
2017-01-01
Full Text Available Objective. To investigate whether high-flow nasal cannula (HFNC oxygen therapy is superior to conventional oxygen therapy for reducing hypoxemia and postoperative pulmonary complications (PPC in patients with thoracoscopic lobectomy after extubation. Methods. Patients with intermediate to high risk for PPC were enrolled in this study. Subjects were randomly assigned to HFNC group (HFNCG or conventional oxygen group (COG following extubation. Arterial blood samples were collected after extubation at 1, 2, 6, 12, 24, 48, and 72 h. Patients with postoperative hypoxemia and PPC were recorded. Adverse events were also documented. Results. Totally 110 patients were randomly assigned to HFNCG (n=56 and COG (n=54. The occurrence rate of hypoxemia in COG was twice more than that in HFNCG (29.62% versus 12.51%, P0.05. Adverse effects as throat and nasal pain occurred more frequently in COG. Conclusions. HFNC application improves oxygenation and reduces the risk of reintubation following thoracoscopic lobectomy but cannot decrease the incidence of PPC.
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The effect of oxygen-doping on the electrical resistivity of vanadium
International Nuclear Information System (INIS)
Lang, E.; Bressers, J.
1975-01-01
High-purity vanadium single crystals characterized by resistance ratios in the range of 1,100 were doped to different oxygen levels and their electrical resistivity increase was measured as a function of the oxygen concentration. In the temperature range investigated, 77 to 293 K, the Matthiessen rule is obeyed. The increase in electrical resistivity per atomic percent oxygen is shown to be 5.16 μΩcm. For the ideal resistivity ratio rhosub(i) (77 K)/rhosub(i) (293 K) a value of 0.116 could be determined. (orig.) [de
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Ma, Yi-Ran; Ren, Si-Hua; He, Yu-Xin; Wang, Lin-Lin; Jin, Li; Hao, Yi-Wen
2012-10-01
This study purposed to investigate the effects of different oxygen concentrations and reactive oxygen species (ROS) on the biological characteristics of hematopoietic stem cells (HSC) and their possible mechanisms through simulating oxygen environment to which the peripheral blood HSC are subjected in peripheral blood HSCT. The proliferation ability, cell cycle, directed differentiation ability, ROS level and hematopoietic reconstitution ability of Lin(-)c-kit(+)Sca-1(+) BMHSC were detected by using in vitro amplification test, directional differentiation test, cell cycle analysis, ROS assay and transplantation of Lin(-)c-kit(+)Sca-1(+) HSC from sublethally irradiated mice respectively. The results showed that oxygen concentrations lower than normal oxygen concentration, especially in hypoxic oxygen environment, could reduce ROS generation and amplify more primitive CD34(+)AC133(+) HSC and active CD34(+) HSC, and maintain more stem cells in the G(0)/G(1) phase, which is more helpful to the growth of CFU-S and viability of mice. At the same time, BMHSC exposed to normal oxygen level or inconstant and greatly changed oxygen concentrations could produce a high level of ROS, and the above-mentioned features and functional indicators are relatively low. It is concluded that ROS levels of HSC in BMHSCT are closely related with the oxygen concentration surrounding the cells and its stability. Low oxygen concentration and antioxidant intervention are helpful to transplantation of BMHSC.
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Directory of Open Access Journals (Sweden)
Rao Govind
2009-01-01
Full Text Available Abstract Background Small-scale microbial fermentations are often assumed to be homogeneous, and oxygen limitation due to inadequate micromixing is often overlooked as a potential problem. To assess the relative degree of micromixing, and hence propensity for oxygen limitation, a new cellular oxygen sensor has been developed. The oxygen responsive E. coli nitrate reductase (nar promoter was used to construct an oxygen reporter plasmid (pNar-GFPuv which allows cell-based reporting of oxygen limitation. Because there are greater than 109 cells in a fermentor, one can outfit a vessel with more than 109 sensors. Our concept was tested in high density, lab-scale (5 L, fed-batch, E. coli fermentations operated with varied mixing efficiency – one verses four impellers. Results In both cases, bioreactors were maintained identically at greater than 80% dissolved oxygen (DO during batch phase and at approximately 20% DO during fed-batch phase. Trends for glucose consumption, biomass and DO showed nearly identical behavior. However, fermentations with only one impeller showed significantly higher GFPuv expression than those with four, indicating a higher degree of fluid segregation sufficient for cellular oxygen deprivation. As the characteristic time for GFPuv expression (approx 90 min. is much larger than that for mixing (approx 10 s, increased specific fluorescence represents an averaged effect of oxygen limitation over time and by natural extension, over space. Conclusion Thus, the pNar-GFPuv plasmid enabled bioreactor-wide oxygen sensing in that bacterial cells served as individual recirculating sensors integrating their responses over space and time. We envision cell-based oxygen sensors may find utility in a wide variety of bioprocessing applications.
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An evaluation of oxygen systems for treatment of childhood pneumonia
Directory of Open Access Journals (Sweden)
Rudan Igor
2011-04-01
Full Text Available Abstract Background Oxygen therapy is recommended for all of the 1.5 – 2.7 million young children who consult health services with hypoxemic pneumonia each year, and the many more with other serious conditions. However, oxygen supplies are intermittent throughout the developing world. Although oxygen is well established as a treatment for hypoxemic pneumonia, quantitative evidence for its effect is lacking. This review aims to assess the utility of oxygen systems as a method for reducing childhood mortality from pneumonia. Methods Aiming to improve priority setting methods, The Child Health and Nutrition Research Initiative (CHNRI has developed a common framework to score competing interventions into child health. That framework involves the assessment of 12 different criteria upon which interventions can be compared. This report follows the proposed framework, using a semi-systematic literature review and the results of a structured exercise gathering opinion from experts (leading basic scientists, international public health researchers, international policy makers and representatives of pharmaceutical companies, to assess and score each criterion as their “collective optimism” towards each, on a scale from 0 to 100%. Results A rough estimate from an analysis of the literature suggests that global strengthening of oxygen systems could save lives of up to 122,000 children from pneumonia annually. Following 12 CHNRI criteria, the experts expressed very high levels of optimism (over 80% for answerability, low development cost and low product cost; high levels of optimism (60-80% for low implementation cost, likelihood of efficacy, deliverability, acceptance to end users and health workers; and moderate levels of optimism (40-60% for impact on equity, affordability and sustainability. The median estimate of potential effectiveness of oxygen systems to reduce the overall childhood pneumonia mortality was ~20% (interquartile range: 10-35%, min
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International Nuclear Information System (INIS)
Burke, T.R.; Johnson, R.J.; Krishnamsetty, C.B.; Sako, K.; Karakousis, C.; Wojtas, F.
1980-01-01
Teflon-covered platinum oxygen probes were used to monitor tissue oxygen levels in post-surgical cancer patients and those treated with radiotherapy. Progressive wound healing was usually accompanied by a decrease in tissue pO2. Radiotherapy produced a slight increase in pO2 while hyperthermia effected a significant increase in the oxygen level during 100% oxygen breathing
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International Nuclear Information System (INIS)
Li, Zheng; Kraner, H.W.; Verbitskaya, E.; Eremin, V.; Ivanov, A.; Rubinelli, F.A.; Fonash, S.J.
1992-02-01
Distributions of the A-center (oxygen-vacancy) in neutron silicon detectors have been studied using Deep Level Transient Spectroscopy. A-centers have been found to be nearly uniformly distributed in the silicon water depth for medium resistivity (0.1 - 0.2 kΩ-cm) silicon detectors. A positive filling pulse was needed to detect the A-centers in high resistivity (>4 kΩ-cm) silicon detectors, and this effect was found to be dependent on the oxidation temperature. A discussion of this effect is presented. 16 refs
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Coping with cyclic oxygen availability: evolutionary aspects.
Flück, Martin; Webster, Keith A; Graham, Jeffrey; Giomi, Folco; Gerlach, Frank; Schmitz, Anke
2007-10-01
Both the gradual rise in atmospheric oxygen over the Proterozoic Eon as well as episodic fluctuations in oxygen over several million-year time spans during the Phanerozoic Era, have arguably exerted strong selective forces on cellular and organismic respiratory specialization and evolution. The rise in atmospheric oxygen, some 2 billion years after the origin of life, dramatically altered cell biology and set the stage for the appearance of multicelluar life forms in the Vendian (Ediacaran) Period of the Neoproterozoic Era. Over much of the Paleozoic, the level of oxygen in the atmosphere was near the present atmospheric level (21%). In the Late Paleozoic, however, there were extended times during which the level of atmospheric oxygen was either markedly lower or markedly higher than 21%. That these Paleozoic shifts in atmospheric oxygen affected the biota is suggested by the correlations between: (1) Reduced oxygen and the occurrences of extinctions, a lowered biodiversity and shifts in phyletic succession, and (2) During hyperoxia, the corresponding occurrence of phenomena such as arthropod gigantism, the origin of insect flight, and the evolution of vertebrate terrestriality. Basic similarities in features of adaptation to hyopoxia, manifest in living organisms at levels ranging from genetic and cellular to physiological and behavioral, suggest the common and early origin of a suite of adaptive mechanisms responsive to fluctuations in ambient oxygen. Comparative integrative approaches addressing the molecular bases of phenotypic adjustments to cyclic oxygen fluctuation provide broad insight into the incremental steps leading to the early evolution of homeostatic respiratory mechanisms and to the specialization of organismic respiratory function.
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2017-10-01
AWARD NUMBER: W81XWH-12-1-0588 TITLE: Supplemental Perioperative Oxygen to Reduce Surgical Site Infection after High- Energy Fracture Surgery...High- Energy Fracture Surgery 5a. CONTRACT NUMBER W81XWH-12-1-0588 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Robert V. O’Toole, MD...14 4 1. INTRODUCTION: The overall scope of this project is to address the treatment of high- energy military fractures, which has
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Liu, Rongrong; Spicer, Graham; Chen, Siyu; Zhang, Hao F.; Yi, Ji; Backman, Vadim
2017-02-01
Oxygen saturation (sO2) of red blood cells (RBCs) in capillaries can indirectly assess local tissue oxygenation and metabolic function. For example, the altered retinal oxygenation in diabetic retinopathy and local hypoxia during tumor development in cancer are reflected by abnormal sO2 of local capillary networks. However, it is far from clear whether accurate label-free optical oximetry (i.e., measuring hemoglobin sO2) is feasible from dispersed RBCs at the single capillary level. The sO2-dependent hemoglobin absorption contrast present in optical scattering signal is complicated by geometry-dependent scattering from RBCs. We present a numerical study of backscattering spectra from single RBCs based on the first-order Born approximation, considering practical factors: RBC orientations, size variation, and deformations. We show that the oscillatory spectral behavior of RBC geometries is smoothed by variations in cell size and orientation, resulting in clear sO2-dependent spectral contrast. In addition, this spectral contrast persists with different mean cellular hemoglobin content and different deformations of RBCs. This study shows for the first time the feasibility of, and provides a theoretical model for, label-free optical oximetry at the single capillary level using backscattering-based imaging modalities, challenging the popular view that such measurements are impossible at the single capillary level.
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Directory of Open Access Journals (Sweden)
A. I. Lenkin
2012-01-01
Full Text Available Objective: to evaluate the relationship between cerebral oxygenation and hemodynamic and oxygen transport parameters in surgical correction of concomitant acquired heart diseases. Subjects and methods. Informed consent was received from 40 patients who required surgery because of concomitant (two or more acquired heart defects. During procedure, perioperative monitoring of oxygen transport and cerebral oxygenation was performed with the aid of PiCCO2 monitor (Pulsion Medical Systems, Germany and a Fore-Sight cerebral oximeter (CASMED, USA. Anesthesia was maintained with propofol and fen-tanyl, by monitoring the depth of anesthesia. Early postoperative intensive therapy was based on the protocol for early targeted correction of hemodynamic disorders. Oxygen transport and cerebral oxygenation parameters were estimated intraopera-tively and within 24 postoperative hours. A statistical analysis including evaluation of Spearman correlations was performed with the aid of SPSS 15.0. Results. During perfusion, there was a relationship between cerebral oximetry values and hemat-ocrit levels, and oxygen partial pressure in the venous blood. Furthermore, a negative correlation between cerebral oximetry values and blood lactate levels was found 30 minutes after initiation of extracorporeal circulation (EC. During the study, there was a positive correlation between cerebral oxygenation and values of cardiac index, central venous saturation, and oxygen delivery index. There was a negative relationship between cerebral oxygenation and extravascular lung water at the beginning of surgery and a correlation between cerebral oximetry values and oxygenation index by the end of the first 24 postoperative hours. Conclusion. The cerebral oxygenation values correlate -with the main determinants of oxygen transport during EC and after cardiac surgical procedures. Cerebral oximetry may be used in early targeted therapy for the surgical correction of acquired combined
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Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V. E-mail: svb@physics.unipune.ernet.in
2001-10-01
The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E{sub c}) and at 415 K (0.9 below E{sub c}); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E{sub c} known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E{sub c} is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species.
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Novel Membranes and Processes for Oxygen Enrichment
Energy Technology Data Exchange (ETDEWEB)
Lin, Haiqing
2011-11-15
using a Bloom baffle burner at GTI. The results are positive and confirm that oxygen-enriched combustion can be carried out without producing higher levels of NOx than normal air firing, if lancing of combustion air is used and the excess air levels are controlled. A simple economic study shows that the membrane processes can produce O{sub 2} at less than $40/ton EPO{sub 2} and an energy cost of 1.1-1.5 MMBtu/ton EPO{sub 2}, which are very favorable compared with conventional technologies such as cryogenics and vacuum pressure swing adsorption processes. The benefits of integrated membrane processes/combustion process trains have been evaluated, and show good savings in process costs and energy consumption, as well as reduced CO{sub 2} emissions. For example, if air containing 30% oxygen is used in natural gas furnaces, the net natural gas savings are an estimated 18% at a burner temperature of 2,500 F, and 32% at a burner temperature of 3,000 F. With a 20% market penetration of membrane-based oxygen-enriched combustion in all combustion processes by 2020, the energy savings would be 414-736 TBtu/y in the U.S. The comparable net cost savings are estimated at $1.2-2.1 billion per year by 2020, calculated as the value of fuel savings subtracted from the cost of oxygen production. The fuel savings of 18%-32% by the membrane/oxygen-enriched combustion corresponds to an 18%-32% reduction in CO{sub 2} emissions, or 23-40 MM ton/y less CO{sub 2} from natural gas-fired furnaces by 2020. In summary, results from this project (Concept Definition phase) are highly promising and clearly demonstrate that membrane processes can produce oxygen-enriched air in a low cost manner that will lower operating costs and energy consumption in industrial combustion processes. Future work will focus on proof-of-concept bench-scale demonstration in the laboratory.
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International Nuclear Information System (INIS)
Congleton, J.; Shih, H.C.; Shoji, T.; Parkins, R.N.
1985-01-01
Slow strain rate stress corrosion tests have been performed on Type 316 stainless steel in 265 C water containing from 0 to 45 ppm oxygen and from < 0.1 to 1000 ppm chloride. The main difference between the present data and previously published results, the latter mainly for Type 304 stainless steel, is that as well as cracking occurring in water containing high oxygen and chloride, it is shown that a cracking regime exists at very low oxygen contents for a wide range of chloride contents. The type of cracking varies with the oxygen and chloride content of the water and the most severe cracking was of comparable extent in both the gauge length and the necked region of the specimen. The least severe cracking only caused cracks to occur in the necked region of the specimen and there was a range of oxygen and chloride contents in which no cracking occurred. The rest potential for annealed Type 316 stainless steel has been mapped for a wide range of oxygen and chloride content waters and it is shown that at 265 C the 'no-cracking' regime of the oxygen-chloride diagram corresponds to potentials in the range -200 to +150 mV(SHE). (author)
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International Nuclear Information System (INIS)
Bache, Matthias; Reddemann, Rolf; Said, Harun M.; Holzhausen, Hans-Juergen; Taubert, Helge; Becker, Axel; Kuhnt, Thomas; Haensgen, Gabriele; Dunst, Juergen; Vordermark, Dirk
2006-01-01
Purpose: The tumor-associated glycoprotein osteopontin (OPN) is discussed as a plasma marker of tumor hypoxia. However, the association of immunohistochemical OPN expression in tumor sections with tumor oxygenation parameters (HF5, median pO 2 ), the hypoxia-related markers hypoxia-inducible factor-1α (HIF-1α) and carbonic anhydrase IX (CAIX), or hemoglobin and systemic vascular endothelial growth factor (VEGF) levels has not been investigated. Methods and Materials: Tumor tissue sections of 34 patients with advanced head-and-neck cancer treated with radiotherapy were assessed by immunochemistry for the expression of OPN, HIF-1α, and CA IX. Relationship of OPN expression with tumor oxygenation parameters (HF5, median pO 2 ), HIF-1α and CA IX expression, hemoglobin and serum VEGF level, and clinical parameters was studied. Results: Bivariate analysis showed a significant correlation of positive OPN staining with low hemoglobin level (p = 0.02), high HIF-1α expression (p = 0.02), and high serum vascular endothelial growth factor level (p = 0.02) for advanced head-and-neck cancer. Furthermore, considering the 31 Stage IV patients, the median pO 2 correlated significantly with the OPN expression (p = 0.02). OPN expression alone had only a small impact on prognosis. However, in a univariate Cox proportional hazard regression model, the expression of either OPN or HIF-1α or CA IX was associated with a 4.1-fold increased risk of death (p = 0.02) compared with negativity of all three markers. Conclusion: Osteopontin expression detected immunohistochemically is associated with oxygenation parameters in advanced head-and-neck cancer. When the results of OPN, HIF-1α, and CA IX immunohistochemistry are combined into a hypoxic profile, a strong and statistically significant impact on overall survival is found
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How oxygen attacks [FeFe] hydrogenases from photosynthetic organisms
Stripp, Sven T.; Goldet, Gabrielle; Brandmayr, Caterina; Sanganas, Oliver; Vincent, Kylie A.; Haumann, Michael; Armstrong, Fraser A.; Happe, Thomas
2009-01-01
Green algae such as Chlamydomonas reinhardtii synthesize an [FeFe] hydrogenase that is highly active in hydrogen evolution. However, the extreme sensitivity of [FeFe] hydrogenases to oxygen presents a major challenge for exploiting these organisms to achieve sustainable photosynthetic hydrogen production. In this study, the mechanism of oxygen inactivation of the [FeFe] hydrogenase CrHydA1 from C. reinhardtii has been investigated. X-ray absorption spectroscopy shows that reaction with oxygen results in destruction of the [4Fe-4S] domain of the active site H-cluster while leaving the di-iron domain (2FeH) essentially intact. By protein film electrochemistry we were able to determine the order of events leading up to this destruction. Carbon monoxide, a competitive inhibitor of CrHydA1 which binds to an Fe atom of the 2FeH domain and is otherwise not known to attack FeS clusters in proteins, reacts nearly two orders of magnitude faster than oxygen and protects the enzyme against oxygen damage. These results therefore show that destruction of the [4Fe-4S] cluster is initiated by binding and reduction of oxygen at the di-iron domain—a key step that is blocked by carbon monoxide. The relatively slow attack by oxygen compared to carbon monoxide suggests that a very high level of discrimination can be achieved by subtle factors such as electronic effects (specific orbital overlap requirements) and steric constraints at the active site. PMID:19805068
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Chung, Soon Cheol; Kim, Ik Hyeon; Tack, Gye Rae; Sohn, Jin Hun
2004-04-01
This study investigated the effects of 30% oxygen administration on the visuospatial cognitive performance using fMRI. Eight college students (right-handed, average age 23.5) were selected as subjects for this study. Oxygen supply equipment which gives 21% and 30% oxygen at a constant rate of 8L/min was developed for this study. To measure the performance of visuospatial cognition, two questionnaires with similar difficulty containing 20 questions each were also developed. Experiment was designed as two runs: run for visuospatial cognition test with normal air (21% of oxygen) and run for visuospatial cognition test with highly concentrated air (30% of oxygen). Run consists of 4 blocks and each block has 8 control problems and 5 visuospatial problems. Functional brain images were taken from 3T MRI using single-shot EPI method. Activities of neural network due to performing visuospatial cognition test were identified using subtraction procedure, and activation areas while performing visuospatial cognition test were extracted using double subtraction procedure. Activities were observed at occipital lobe, parietal lobe, and frontal lobe when performing visuospatial cognition test following both 21% and 30% oxygen administration. But in case of only 30% oxygen administration there were more activities at left precuneus, left cuneus, right postcentral gyrus, bilateral middle frontal gyri, right inferior frontal gyrus, left superior frontal gyrus, bilateral uvula, bilateral pyramis, and nodule compared with 21% oxygen administration. From results of visuospatial cognition test, accuracy rate increased in case of 30% oxygen administration. Thus it could be concluded that highly concentrated oxygen administration has positive effects on the visuospatial cognitive performance.
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International Nuclear Information System (INIS)
Mitamura, Yoshinori; Okamoto, Eiji
2015-01-01
This study was carried out to clarify the effect of a high gradient magnetic field on pressure characteristics of blood in a hollow fiber membrane oxygenator in a solenoid coil by means of numerical analysis. Deoxygenated erythrocytes are paramagnetic, and oxygenated erythrocytes are diamagnetic. Blood changes its magnetic susceptibility depending on whether it is carrying oxygen or not. Motion of blood was analyzed by solving the continuous equation and the Navier–Stokes equation. It was confirmed that oxygenation of deoxygenated blood in the downstream side of the applied magnetic field was effective for pressure rise in a non-uniform magnetic field. The pressure rise was enhanced greatly by an increase in magnetic field intensity. The results suggest that a membrane oxygenator works as an actuator and there is a possibility of self-circulation of blood through an oxygenator in a non-uniform magnetic field. - Highlights: • Effects of a gradient magnetic field on erythrocytes in an oxygenator were analyzed. • Blood changes magnetic susceptibility depending on if it is carrying oxygen or not. • Oxygenation of deoxygenated blood is effective for pressure rise in a magnetic field. • A membrane oxygenator works as an actuator. • There is a possibility of self-circulation of blood through an oxygenator
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Energy Technology Data Exchange (ETDEWEB)
Mitamura, Yoshinori, E-mail: ymitamura@par.odn.ne.jp; Okamoto, Eiji, E-mail: okamoto@tspirit.tokai-u.jp
2015-04-15
This study was carried out to clarify the effect of a high gradient magnetic field on pressure characteristics of blood in a hollow fiber membrane oxygenator in a solenoid coil by means of numerical analysis. Deoxygenated erythrocytes are paramagnetic, and oxygenated erythrocytes are diamagnetic. Blood changes its magnetic susceptibility depending on whether it is carrying oxygen or not. Motion of blood was analyzed by solving the continuous equation and the Navier–Stokes equation. It was confirmed that oxygenation of deoxygenated blood in the downstream side of the applied magnetic field was effective for pressure rise in a non-uniform magnetic field. The pressure rise was enhanced greatly by an increase in magnetic field intensity. The results suggest that a membrane oxygenator works as an actuator and there is a possibility of self-circulation of blood through an oxygenator in a non-uniform magnetic field. - Highlights: • Effects of a gradient magnetic field on erythrocytes in an oxygenator were analyzed. • Blood changes magnetic susceptibility depending on if it is carrying oxygen or not. • Oxygenation of deoxygenated blood is effective for pressure rise in a magnetic field. • A membrane oxygenator works as an actuator. • There is a possibility of self-circulation of blood through an oxygenator.
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Electrochemical extraction of oxygen using PEM electrolysis technology
Directory of Open Access Journals (Sweden)
BOULBABA ELADEB
2012-11-01
Full Text Available Electrochemical extraction of oxygen from air can be carried out by chemical reduction of oxygen at the cathode and simultaneous oxygen evolution by water anode oxidation. The present investigation deals with the use of an electrolysis cell of PEM technology for this purpose. A dedicated 25 cm2 cell provided with a commercial water electrolysis MEA and titanium grooved plates has been designed for continuous operation at pressures close to the ambient level. The MEA consisted of a Nafion 117 membrane sandwiched between a Pt/C cathode and a non-supported Pt-Ir anode. Oxygen partial consumption in long-term runs was evaluated by analysis of the outlet air by gas chromatography, depending on the cell voltage - or the current density - and the excess in air oxygen fed to the cathode. Runs over more 50 hours indicated the relative stability of the components used for current densities ranging from 0.1 to 0.2 A cm-2 with high efficiency of oxygen reduction. Higher current density could be envisaged with more efficient MEA’s, exhibiting lower overpotentials for oxygen evolution to avoid too significant degradation of the anode material and the membrane. Interpretation of the data has been carried out by calculation of the cathode current efficiency.
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Molecular Orbital Principles of Oxygen-Redox Battery Electrodes.
Okubo, Masashi; Yamada, Atsuo
2017-10-25
Lithium-ion batteries are key energy-storage devices for a sustainable society. The most widely used positive electrode materials are LiMO 2 (M: transition metal), in which a redox reaction of M occurs in association with Li + (de)intercalation. Recent developments of Li-excess transition-metal oxides, which deliver a large capacity of more than 200 mAh/g using an extra redox reaction of oxygen, introduce new possibilities for designing higher energy density lithium-ion batteries. For better engineering using this fascinating new chemistry, it is necessary to achieve a full understanding of the reaction mechanism by gaining knowledge on the chemical state of oxygen. In this review, a summary of the recent advances in oxygen-redox battery electrodes is provided, followed by a systematic demonstration of the overall electronic structures based on molecular orbitals with a focus on the local coordination environment around oxygen. We show that a π-type molecular orbital plays an important role in stabilizing the oxidized oxygen that emerges upon the charging process. Molecular orbital principles are convenient for an atomic-level understanding of how reversible oxygen-redox reactions occur in bulk, providing a solid foundation toward improved oxygen-redox positive electrode materials for high energy-density batteries.
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Gilkey, Kelly M.; Olson, Sandra L.
2015-01-01
An oxygen concentrator is needed to provide enriched oxygen in support of medical contingency operations for future exploration human spaceflight programs. It would provide continuous oxygen to an ill or injured crew member in a closed cabin environment. Oxygen concentration technology is being pursued to concentrate oxygen from the ambient environment so oxygen as a consumable resource can be reduced. Because oxygen is a critical resource in manned spaceflight, using an oxygen concentrator to pull oxygen out of the ambient environment instead of using compressed oxygen can provide better optimization of resources. The overall goal of this project is to develop an oxygen concentrator module that minimizes the hardware mass, volume, and power footprint while still performing at the required clinical capabilities. Should a medical event occur that requires patient oxygenation, the release of 100 percent oxygen into a small closed cabin environment can rapidly raise oxygen levels to the vehicles fire limit. The use of an oxygen concentrator to enrich oxygen from the ambient air and concentrate it to the point where it can be used for medical purposes means no oxygen is needed from the ultra-high purity (99.5+% O2) oxygen reserve tanks. By not adding oxygen from compressed tanks to the cabin environment, oxygen levels can be kept below the vehicle fire limit thereby extending the duration of care provided to an oxygenated patient without environmental control system intervention to keep the cabin oxygen levels below the fire limits. The oxygen concentrator will be a Food and Drug Administration (FDA) clearable device. A demonstration unit for the International Space Station (ISS) is planned to verify the technology and provide oxygen capability. For the ISS, the demonstration unit should not exceed 10 kg (approximately 22 lb), which is the soft stowage mass limit for launch on resupply vehicles for the ISS. The unit's size should allow for transport within the
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Deep Nitrate Deficit Observed in the Highly Oxygenated East/Japan Sea and Its Possible Cause
Directory of Open Access Journals (Sweden)
Il-Nam Kim
2012-01-01
Full Text Available We present evidence of denitrification on the continental slopes of the Ulleung Basin (UB and the Eastern Japan Basin (EJB near the Tatar Strait (TtS in the East/Japan Sea (EJS, despite its high water column dissolved oxygen concentrations. Some nutrient concentration data deviate significantly from the fitted regression line of nitrate (N vs. phosphate (P in deep waters, indicating a loss of nitrate in the region. The EJS has a lower N/P ratio (ca. 12.4 below 300 dbar than a traditional Redfield ratio (16. The N/P ratio and oxygen concentration are substantially lower at several locations whose depths are close to the sediment-water interface, near TtS (500 - 1100 dbar and in UB (1100 - 2200 dbar. The decreased nitrate concentration is smaller than the expected nitrate level (a low N/P ratio of < 12.4, and a secondary nitrite peak near the bottom of these two regions: taken collectively, both indicate the presence of denitrification in the bottom layer. It is speculated that active re-mineralization and denitrification may occur simultaneously along the rich organic matter bottom layer on the slope environment. Denitrification rates are estimated at ~3 - 33 μmol N m-2 d-1. Current estimates do not support the previous idea of basin-wide denitrification in EJS, although the N/P ratio is low like in other hypoxic/anoxic seas. A better understanding of the denitrification process is necessary for predicting future changes of nitrogen cycle in the well-oxygenated EJS considering the decadal-scale physical and biogeochemical changes that have occurred.
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DEFF Research Database (Denmark)
Jensen, Pia; Gramsbergen, Jan-Bert; Zimmer, Jens
2011-01-01
Effective numerical expansion of dopaminergic precursors might overcome the limited availability of transplantable cells in replacement strategies for Parkinson's disease. Here we investigated the effect of fibroblast growth factor-2 (FGF2) and FGF8 on expansion and dopaminergic differentiation o...... enzyme activity, which may explain the elevated dopamine levels. Our findings demonstrate that modulation of oxygen tension is a recognizable factor for in vitro expansion and dopaminergic differentiation of rat embryonic midbrain precursor cells....... of rat embryonic ventral mesencephalic neuroblasts cultured at high (20%) and low (3%) oxygen tension. More cells incorporated bromodeoxyuridine in cultures expanded at low as compared to high oxygen tension, and after 6 days of differentiation there were significantly more neuronal cells in low than......, switching FGF2-expanded cultures from low to high oxygen tension during the last two days of differentiation significantly enhanced dopamine release and intracellular dopamine levels as compared to all other treatment groups. In addition, the short-term exposure to high oxygen enhanced in situ assessed TH...
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Guo, Bingkun; Kong, Qingyu; Zhu, Ying; Mao, Ya; Wang, Zhaoxiang; Wan, Meixiang; Chen, Liquan
2011-12-23
Current lithium-ion battery (LIB) technologies are all based on inorganic electrode materials, though organic materials have been used as electrodes for years. Disadvantages such as limited thermal stability and low specific capacity hinder their applications. On the other hand, the transition metal oxides that provide high lithium-storage capacity by way of electrochemical conversion reaction suffer from poor cycling stability. Here we report a novel high-performance, organic, lithium-storage material, a polypyrrole-cobalt-oxygen (PPy-Co-O) coordination complex, with high lithium-storage capacity and excellent cycling stability. Extended X-ray absorption fine structure and Raman spectroscopy and other physical and electrochemical characterizations demonstrate that this coordination complex can be electrochemically fabricated by cycling PPy-coated Co(3)O(4) between 0.0 V and 3.0 V versus Li(+)/Li. Density functional theory (DFT) calculations indicate that each cobalt atom coordinates with two nitrogen atoms within the PPy-Co coordination layer and the layers are connected with oxygen atoms between them. Coordination weakens the C-H bonds on PPy and makes the complex a novel lithium-storage material with high capacity and high cycling stability. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Avni, Reut; Golani, Ofra; Akselrod-Ballin, Ayelet; Cohen, Yonni; Biton, Inbal; Garbow, Joel R; Neeman, Michal
2016-07-01
Purpose To generate magnetic resonance (MR) imaging-derived, oxygen-hemoglobin dissociation curves and to map fetal-placental oxygen-hemoglobin affinity in pregnant mice noninvasively by combining blood oxygen level-dependent (BOLD) T2* and oxygen-weighted T1 contrast mechanisms under different respiration challenges. Materials and Methods All procedures were approved by the Weizmann Institutional Animal Care and Use Committee. Pregnant mice were analyzed with MR imaging at 9.4 T on embryonic days 14.5 (eight dams and 58 fetuses; imprinting control region ICR strain) and 17.5 (21 dams and 158 fetuses) under respiration challenges ranging from hyperoxia to hypoxia (10 levels of oxygenation, 100%-10%; total imaging time, 100 minutes). A shorter protocol with normoxia to hyperoxia was also performed (five levels of oxygenation, 20%-100%; total imaging time, 60 minutes). Fast spin-echo anatomic images were obtained, followed by sequential acquisition of three-dimensional gradient-echo T2*- and T1-weighted images. Automated registration was applied to align regions of interest of the entire placenta, fetal liver, and maternal liver. Results were compared by using a two-tailed unpaired Student t test. R1 and R2* values were derived for each tissue. MR imaging-based oxygen-hemoglobin dissociation curves were constructed by nonlinear least square fitting of 1 minus the change in R2*divided by R2*at baseline as a function of R1 to a sigmoid-shaped curve. The apparent P50 (oxygen tension at which hemoglobin is 50% saturated) value was derived from the curves, calculated as the R1 scaled value (x) at which the change in R2* divided by R2*at baseline scaled (y) equals 0.5. Results The apparent P50 values were significantly lower in fetal liver than in maternal liver for both gestation stages (day 14.5: 21% ± 5 [P = .04] and day 17.5: 41% ± 7 [P hemoglobin dissociation curves with a shorter protocol that excluded the hypoxic periods was demonstrated. Conclusion MR imaging
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Some Applications of Fast Neutron Activation Analysis of Oxygen
Energy Technology Data Exchange (ETDEWEB)
Owrang, Farshid
2003-07-01
In this thesis we focus on applications of neutron activation of oxygen for several purposes: A) measuring the water level in a laboratory tank, B) measuring the water flow in a pipe system set-up, C) analysing the oxygen in combustion products formed in a modern gasoline SI engine, and D) measuring on-line the amount of oxygen in bulk liquids. A) Water level measurements. The purpose of this work was to perform radiation based water level measurements, aimed at nuclear reactor vessels, on a laboratory scale. A laboratory water tank was irradiated by fast neutrons from a neutron generator. The water was activated at different water levels and the water level was decreased. The produced gamma radiation was measured using two detectors at different heights. The results showed that the method is suitable for measurement of water level and that a relatively small experimental set-up can be used for developing methods for water level measurements in real boiling water reactors based on activated oxygen in the water. B) Water flows in pipe. The goal in this work was to investigate the asymmetric distribution of activity in flow measurements with pulsed neutron activation (PNA) in a laboratory piping system. Earlier investigations had shown a discrepancy between the measured velocity of the activated water by PNA and the true mean velocity in the pipe. This discrepancy decreased with larger distances from the activation point. It was speculated that the induced activity in the pipe did not distribute homogeneously. With inhomogeneous radial distribution of activity in combination with a velocity profile in the pipe, the activated water may not have the same velocity as the mean velocity of water in the pipe. To study this phenomenon, a water-soluble colour was injected into a transparent pipe for simulation of the transport of the activated water. The radial concentration of the colour, at different distances from the activation point, was determined. The result
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Some Applications of Fast Neutron Activation Analysis of Oxygen
International Nuclear Information System (INIS)
Owrang, Farshid
2003-01-01
In this thesis we focus on applications of neutron activation of oxygen for several purposes: A) measuring the water level in a laboratory tank, B) measuring the water flow in a pipe system set-up, C) analysing the oxygen in combustion products formed in a modern gasoline SI engine, and D) measuring on-line the amount of oxygen in bulk liquids. A) Water level measurements. The purpose of this work was to perform radiation based water level measurements, aimed at nuclear reactor vessels, on a laboratory scale. A laboratory water tank was irradiated by fast neutrons from a neutron generator. The water was activated at different water levels and the water level was decreased. The produced gamma radiation was measured using two detectors at different heights. The results showed that the method is suitable for measurement of water level and that a relatively small experimental set-up can be used for developing methods for water level measurements in real boiling water reactors based on activated oxygen in the water. B) Water flows in pipe. The goal in this work was to investigate the asymmetric distribution of activity in flow measurements with pulsed neutron activation (PNA) in a laboratory piping system. Earlier investigations had shown a discrepancy between the measured velocity of the activated water by PNA and the true mean velocity in the pipe. This discrepancy decreased with larger distances from the activation point. It was speculated that the induced activity in the pipe did not distribute homogeneously. With inhomogeneous radial distribution of activity in combination with a velocity profile in the pipe, the activated water may not have the same velocity as the mean velocity of water in the pipe. To study this phenomenon, a water-soluble colour was injected into a transparent pipe for simulation of the transport of the activated water. The radial concentration of the colour, at different distances from the activation point, was determined. The result
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A distributed chemosensory circuit for oxygen preference in C. elegans.
Directory of Open Access Journals (Sweden)
Andy J Chang
2006-09-01
Full Text Available The nematode Caenorhabditis elegans has complex, naturally variable behavioral responses to environmental oxygen, food, and other animals. C. elegans detects oxygen through soluble guanylate cyclase homologs (sGCs and responds to it differently depending on the activity of the neuropeptide receptor NPR-1: npr-1(lf and naturally isolated npr-1(215F animals avoid high oxygen and aggregate in the presence of food; npr-1(215V animals do not. We show here that hyperoxia avoidance integrates food with npr-1 activity through neuromodulation of a distributed oxygen-sensing network. Hyperoxia avoidance is stimulated by sGC-expressing oxygen-sensing neurons, nociceptive neurons, and ADF sensory neurons. In npr-1(215V animals, the switch from weak aerotaxis on food to strong aerotaxis in its absence requires close regulation of the neurotransmitter serotonin in the ADF neurons; high levels of ADF serotonin promote hyperoxia avoidance. In npr-1(lf animals, food regulation is masked by increased activity of the oxygen-sensing neurons. Hyperoxia avoidance is also regulated by the neuronal TGF-beta homolog DAF-7, a secreted mediator of crowding and stress responses. DAF-7 inhibits serotonin synthesis in ADF, suggesting that ADF serotonin is a convergence point for regulation of hyperoxia avoidance. Coalitions of neurons that promote and repress hyperoxia avoidance generate a subtle and flexible response to environmental oxygen.
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Ahn, Su Mi; Suk, Jungdon; Kim, Do Youb; Kang, Yongku; Kim, Hwan Kyu; Kim, Dong Wook
2017-10-01
To fabricate a sustainable lithium-oxygen (Li-O 2 ) battery, it is crucial to identify an optimum electrolyte. Herein, it is found that tetramethylene sulfone (TMS) and lithium nitrate (LiNO 3 ) form the optimum electrolyte, which greatly reduces the overpotential at charge, exhibits superior oxygen efficiency, and allows stable cycling for 100 cycles. Linear sweep voltammetry (LSV) and differential electrochemical mass spectrometry (DEMS) analyses reveal that neat TMS is stable to oxidative decomposition and exhibit good compatibility with a lithium metal. But, when TMS is combined with typical lithium salts, its performance is far from satisfactory. However, the TMS electrolyte containing LiNO 3 exhibits a very low overpotential, which minimizes the side reactions and shows high oxygen efficiency. LSV-DEMS study confirms that the TMS-LiNO 3 electrolyte efficiently produces NO 2 - , which initiates a redox shuttle reaction. Interestingly, this NO 2 - /NO 2 redox reaction derived from the LiNO 3 salt is not very effective in solvents other than TMS. Compared with other common Li-O 2 solvents, TMS seems optimum solvent for the efficient use of LiNO 3 salt. Good compatibility with lithium metal, high dielectric constant, and low donicity of TMS are considered to be highly favorable to an efficient NO 2 - /NO 2 redox reaction, which results in a high-performance Li-O 2 battery.
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Oxygen as a driver of early arthropod micro-benthos evolution.
Directory of Open Access Journals (Sweden)
Mark Williams
Full Text Available BACKGROUND: We examine the physiological and lifestyle adaptations which facilitated the emergence of ostracods as the numerically dominant Phanerozoic bivalve arthropod micro-benthos. METHODOLOGY/PRINCIPAL FINDINGS: The PO(2 of modern normoxic seawater is 21 kPa (air-equilibrated water, a level that would cause cellular damage if found in the tissues of ostracods and much other marine fauna. The PO(2 of most aquatic breathers at the cellular level is much lower, between 1 and 3 kPa. Ostracods avoid oxygen toxicity by migrating to waters which are hypoxic, or by developing metabolisms which generate high consumption of O(2. Interrogation of the Cambrian record of bivalve arthropod micro-benthos suggests a strong control on ecosystem evolution exerted by changing seawater O(2 levels. The PO(2 of air-equilibrated Cambrian-seawater is predicted to have varied between 10 and 30 kPa. Three groups of marine shelf-dwelling bivalve arthropods adopted different responses to Cambrian seawater O(2. Bradoriida evolved cardiovascular systems that favoured colonization of oxygenated marine waters. Their biodiversity declined during intervals associated with black shale deposition and marine shelf anoxia and their diversity may also have been curtailed by elevated late Cambrian (Furongian oxygen-levels that increased the PO(2 gradient between seawater and bradoriid tissues. Phosphatocopida responded to Cambrian anoxia differently, reaching their peak during widespread seabed dysoxia of the SPICE event. They lacked a cardiovascular system and appear to have been adapted to seawater hypoxia. As latest Cambrian marine shelf waters became well oxygenated, phosphatocopids went extinct. Changing seawater oxygen-levels and the demise of much of the seabed bradoriid micro-benthos favoured a third group of arthropod micro-benthos, the ostracods. These animals adopted lifestyles that made them tolerant of changes in seawater O(2. Ostracods became the numerically
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Wei, Cynthia; Zhu, Meifang; Petroll, W. Matthew; Robertson, Danielle M.
2014-01-01
Purpose. To establish a rabbit model of infectious Pseudomonas aeruginosa keratitis using ultrahigh oxygen transmissible rigid lenses and characterize the frequency and severity of infection when compared to a non–oxygen transmissible lens material. Methods. Rabbits were fit with rigid lenses composed of ultrahigh and non–oxygen transmissible materials. Prior to wear, lenses were inoculated with an invasive corneal isolate of P. aeruginosa stably conjugated to green fluorescent protein (GFP). Corneas were examined before and after lens wear using a modified Heidelberg Rostock Tomograph in vivo confocal microscope. Viable bacteria adherent to unworn and worn lenses were assessed by standard plate counts. The presence of P. aeruginosa-GFP and myeloperoxidase-labeled neutrophils in infected corneal tissue was evaluated using laser scanning confocal microscopy. Results. The frequency and severity of infectious keratitis was significantly greater with inoculated ultrahigh oxygen transmissible lenses. Infection severity was associated with increasing neutrophil infiltration and in severe cases, corneal melting. In vivo confocal microscopic analysis of control corneas following lens wear confirmed that hypoxic lens wear was associated with mechanical surface damage, whereas no ocular surface damage was evident in the high-oxygen lens group. Conclusions. These data indicate that in the absence of adequate tear clearance, the presence of P. aeruginosa trapped under the lens overrides the protective effects of oxygen on surface epithelial cells. These findings also suggest that alternative pathophysiological mechanisms exist whereby changes under the lens in the absence of frank hypoxic damage result in P. aeruginosa infection in the otherwise healthy corneal epithelium. PMID:25125601
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Kim, Sun Yee; Park, Jeen-Woo
2003-03-01
Singlet oxygen (1O2) is a highly reactive form of molecular oxygen that may harm living systems by oxidizing critical cellular macromolecules. Recently, we have shown that NADP+-dependent isocitrate dehydrogenase is involved in the supply of NADPH needed for GSH production against cellular oxidative damage. In this study, we investigated the role of cytosolic form of NADP+-dependent isocitrate dehydrogenase (IDPc) against singlet oxygen-induced cytotoxicity by comparing the relative degree of cellular responses in three different NIH3T3 cells with stable transfection with the cDNA for mouse IDPc in sense and antisense orientations, where IDPc activities were 2.3-fold higher and 39% lower, respectively, than that in the parental cells carrying the vector alone. Upon exposure to singlet oxygen generated from photoactivated dye, the cells with low levels of IDPc became more sensitive to cell killing. Lipid peroxidation, protein oxidation, oxidative DNA damage and intracellular peroxide generation were higher in the cell-line expressing the lower level of IDPc. However, the cells with the highly over-expressed IDPc exhibited enhanced resistance against singlet oxygen, compared to the control cells. The data indicate that IDPc plays an important role in cellular defense against singlet oxygen-induced oxidative injury.
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Radiolytic gas formation in high-level liquid waste solutions
International Nuclear Information System (INIS)
Brodda, B.-G.; Dix, Siegfried; Merz, E.R.
1989-01-01
High-level fission product waste solutions originating from the first-cycle raffinate stream of spent fast breeder reactor fuel reprocessing have been investigated gas chromatographically for their radiolytic and chemical gas production. The solutions showed considerable formation of hydrogen, carbon dioxide and dinitrogen oxide, whereas atmospheric oxygen was consumed completely within a short time. In particular, carbon dioxide resulted from the radiolytic degradation of entrained organic solvent. After nearly complete degradation of the organic solvent, the influence of hydrazine and nitrogen dioxide on hydrogen formation was investigated. Hydrazinium hydroxide led to the formation of dinitrogen oxide and nitrogen. After 60 d, the concentration of dinitrogen oxide had reduced to zero, whereas the amount of nitrogen formed had reached a maximum. This may be explained by simultaneous chemical and radiolytic reactions leading to the formation of dinitrogen oxide and nitrogen and photolytic fission of dinitrogen oxide. Addition of sodium nitrite resulted in the rapid formation of dinitrogen oxide. The rate of hydrogen production was not changed significantly after the addition of hydrazine or nitrite. The results indicate that under normal operating conditions no dangerous hydrogen radiolysis yields should develop in the course of reprocessing and high-level liquid waste tank storage. Organic entrainment may lead to enhanced radiolytic decomposition and thus to considerable hydrogen production rates and pressure build-up in closed systems. (author)
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Evolving Oxygen Landscape of the Early Atmosphere and Oceans
Lyons, T. W.; Reinhard, C. T.; Planavsky, N. J.
2013-12-01
The past decade has witnessed remarkable advances in our understanding of oxygen on the early Earth, and a new framework, the topic of this presentation, is now in place to address the controls on spatiotemporal distributions of oxygen and their potential relationships to deep-Earth processes. Recent challenges to the Archean biomarker record have put an added burden on inorganic geochemistry to fingerprint and quantify the early production, accumulation, and variation of biospheric oxygen. Fortunately, a wide variety of techniques now point convincingly to photosynthetic oxygen production and dynamic accumulation well before the canonical Great Oxidation Event (GOE). Recent modeling of sulfur recycling over this interval allows for transient oxygen accumulation in the atmosphere without the disappearance of non-mass-dependent (NMD) sulfur isotope anomalies from the stratigraphic record and further allows for persistent accumulation in the atmosphere well before the permanent disappearance of NMD signals. This recent work suggests that the initial rise of oxygen may have occurred in fits and starts rather than a single step, and that once permanently present in the atmosphere, oxygen likely rose to high levels and then plummeted, in phase with the Paleoproterozoic Lomagundi positive carbon isotope excursion. More than a billion years of oxygen-free conditions in the deep ocean followed and set a challenging course for life, including limited abundances and diversity of eukaryotic organisms. Despite this widespread anoxia, sulfidic (euxinic) conditions were likely limited to productive ocean margins. Nevertheless, euxinia was sufficiently widespread to impact redox-dependent nutrient relationships, particularly the availability of bioessential trace metals critical in the nitrogen cycle, which spawned feedbacks that likely maintained oxygen at very low levels in the ocean and atmosphere and delayed the arrival of animals. Then, in the mid, pre-glacial Neoproterozoic
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Dynamic mechanisms of cardiac oxygenation during brief ischemia and reperfusion
International Nuclear Information System (INIS)
Parsons, W.J.; Rembert, J.C.; Bauman, R.P.; Greenfield, J.C. Jr.; Piantadosi, C.A.
1990-01-01
Myocardial oxygenation may be altered markedly by changes in tissue blood flow. During brief ischemia and reperfusion produced by transient occlusion of the left anterior descending artery in 10 open-chest dogs, changes in the oxygenation of tissue hemoglobin (Hb) plus myoglobin (Mb) and the oxidation-reduction (redox) state of mitochondrial cytochrome aa3 were monitored continuously using near-infrared spectroscopy. The nondestructive optical technique indicated that coronary occlusion produced an abrupt drop in tissue oxygen stores (tHb02 + Mb02), tissue blood volume (tBV), and the oxidation level of cytochrome aa3. Changes in the cytochrome oxidation state were related inversely to transmural collateral blood flow within the ischemic region (r = 0.77) measured with radiolabeled microspheres. Furthermore, there was a direct relationship (r = 0.91) between collateral blood flow and the tissue level of desaturated Hb and Mb (tHb + Mb). Reperfusion after 2 min of ischemia led to a synchronous overshoot of baseline in coronary flow and tBV followed by supranormal increases in tHb + Mb02 and the oxidation level of cytochrome aa3. The tHb + Mb level increased transiently during reperfusion. This response correlated inversely with collateral flow during ischemia (r = 0.91). Accordingly, the time required to reach peak tHb + Mb levels was shortest in dogs with high collateral flows (r = 0.75). Thus collateral blood flow partially sustains myocardial oxygenation during coronary artery occlusion and influences tissue reoxygenation early during reperfusion
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Micro-texturing into DLC/diamond coated molds and dies via high density oxygen plasma etching
Directory of Open Access Journals (Sweden)
Yunata Ersyzario Edo
2015-01-01
Full Text Available Diamond-Like Carbon (DLC and Chemical Vapor Deposition (CVD-diamond films have been widely utilized not only as a hard protective coating for molds and dies but also as a functional substrate for bio-MEMS/NEMS. Micro-texturing into these hard coated molds and dies provides a productive tool to duplicate the original mother micro-patterns onto various work materials and to construct any tailored micro-textures for sensors and actuators. In the present paper, the high density oxygen plasma etching method is utilized to make micro-line and micro-groove patterns onto the DLC and diamond coatings. Our developing oxygen plasma etching system is introduced together with characterization on the plasma state during etching. In this quantitative plasma diagnosis, both the population of activated species and the electron and ion densities are identified through the emissive light spectroscopy and the Langmuir probe method. In addition, the on-line monitoring of the plasmas helps to describe the etching process. DLC coated WC (Co specimen is first employed to describe the etching mechanism by the present method. Chemical Vapor Deposition (CVD diamond coated WC (Co is also employed to demonstrate the reliable capacity of the present high density oxygen plasma etching. This oxygen plasma etching performance is discussed by comparison of the etching rates.
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Interaction of molecular oxygen with single wall nanotubes: Role of surfactant contamination
International Nuclear Information System (INIS)
Larciprete, R.; Goldoni, A.; Lizzit, S.
2003-01-01
The interaction of molecular oxygen with single wall nanotubes in the form of a commercial bucky paper was investigated by high resolution photoemission spectroscopy. Sodium contamination was found in the sample, which was completely removed only after prolonged heating at 1250 K. The C 1s core level spectrum measured on the sample annealed to 1020 K dramatically changed upon exposure to molecular oxygen. On the contrary, when exposing the Na-free SWNTs to several KL of O 2 , the sample remained oxygen free and no modification in the C 1s core level was observed. Therefore the observed sensitivity of the sample to O 2 was due to a Na mediated oxidation, determining a charge transfer from the C tubes to the Na-O complex
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Dieën, J.H. van; Westebring van der; Putten, E.P.; Kingma, I.; Looze, M.P. de
2009-01-01
This study was designed to determine whether trunk extensor fatigue occurs during low-level activity and whether this is associated with a drop in muscle tissue oxygenation. Electromyography (EMG) feedback was used to impose constant activity in a part of the trunk extensor muscles. We hypothesized
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Kinetics of the high temperature oxygen exchange reaction on {sup 238}PuO{sub 2} powder
Energy Technology Data Exchange (ETDEWEB)
Whiting, Christofer E., E-mail: chris.whiting@udri.udayton.edu [University of Dayton – Research Institute, 300 College Park, Dayton, OH 45469-0172 (United States); Du, Miting; Felker, L. Kevin; Wham, Robert M. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Barklay, Chadwick D.; Kramer, Daniel P. [University of Dayton – Research Institute, 300 College Park, Dayton, OH 45469-0172 (United States)
2015-12-15
Oxygen exchange reactions performed on PuO{sub 2} suggest the reaction is influenced by at least three mechanisms: an internal chemical reaction, surface mobility of active species/defects, and surface exchange of gaseous oxygen with lattice oxygen. Activation energies for the surface mobility and internal chemical reaction are presented. Determining which mechanism is dominant appears to be a complex function including at least specific surface area and temperature. Thermal exposure may also impact the oxygen exchange reaction by causing reductions in the specific surface area of PuO{sub 2}. Previous CeO{sub 2} surrogate studies exhibit similar behavior, confirming that CeO{sub 2} is a good qualitative surrogate for PuO{sub 2}, in regards to the oxygen exchange reaction. Comparison of results presented here with previous work on the PuO{sub 2} oxygen exchange reaction allows complexities in the previous work to be explained. These explanations allowed new conclusions to be drawn, many of which confirm the conclusions presented here. - Highlights: • PuO{sub 2} Oxygen exchange kinetics can be influenced by at least 3 different mechanisms. • An internal chemical reaction controls the rate at high temperature and large SSA. • Surface mobility and surface exchange influence rate at lower temperatures and SSA. • Exchange temperatures may alter SSA and make data difficult to interpret.
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Fang, Chengchi; Guan, Lihong; Zhong, Zaixuan; Gan, Xiaoni; He, Shunping
2015-08-01
One of the most important events in vertebrate evolutionary history is the water-to-land transition, during which some morphological and physiological changes occurred in concert with the loss of specific genes in tetrapods. However, the molecular mechanisms underlying this transition have not been well explored. To explore vertebrate adaptation to different oxygen levels during the water-to-land transition, we performed comprehensive bioinformatics and experimental analysis aiming to investigate the NAMPT family in vertebrates. NAMPT, a rate-limiting enzyme in the salvage pathway of NAD+ biosynthesis, is critical for cell survival in a hypoxic environment, and a high level of NAMPT significantly augments oxidative stress in normoxic environments. Phylogenetic analysis showed that NAMPT duplicates arose from a second round whole-genome duplication event. NAMPTA existed in all classes of vertebrates, whereas NAMPTB was only found in fishes and not tetrapods. Asymmetric evolutionary rates and purifying selection were the main evolutionary forces involved. Although functional analysis identified several functionally divergent sites during NAMPT family evolution, in vitro experimental data demonstrated that NAMPTA and NAMPTB were functionally conserved for NAMPT enzymatic function in the NAD+ salvage pathway. In situ hybridization revealed broad NAMPTA and NAMPTB expression patterns, implying regulatory functions over a wide range of developmental processes. The morpholino-mediated knockdown data demonstrated that NAMPTA was more essential than NAMPTB for vertebrate embryo development. We propose that the retention of NAMPTB in water-breathing fishes and its loss in air-breathing tetrapods resulted from vertebrate adaptation to different oxygen levels during the water-to-land transition. © 2015 FEBS.
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Electron loss from multiply protonated lysozyme ions in high energy collisions with molecular oxygen
DEFF Research Database (Denmark)
Hvelplund, P; Nielsen, SB; Sørensen, M
2001-01-01
We report on the electron loss from multiply protonated lysozyme ions Lys-Hn(n)+ (n = 7 - 17) and the concomitant formation of Lys-Hn(n+1)+. in high-energy collisions with molecular oxygen (laboratory kinetic energy = 50 x n keV). The cross section for electron loss increases with the charge state...... of the precursor from n = 7 to n = 11 and then remains constant when n increases further. The absolute size of the cross section ranges from 100 to 200 A2. The electron loss is modeled as an electron transfer process between lysozyme cations and molecular oxygen....
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Oxygen enrichment incineration
International Nuclear Information System (INIS)
Kim, Jeong Guk; Yang, Hee Chul; Park, Geun Il; Kim, Joon Hyung
2000-10-01
Oxygen enriched combustion technology has recently been used in waste incineration. To apply the oxygen enrichment on alpha-bearing waste incineration, which is being developed, a state-of-an-art review has been performed. The use of oxygen or oxygen-enriched air instead of air in incineration would result in increase of combustion efficiency and capacity, and reduction of off-gas product. Especially, the off-gas could be reduced below a quarter, which might reduce off-gas treatment facilities, and also increase an efficiency of off-gas treatment. However, the use of oxygen might also lead to local overheating and high nitrogen oxides (NOx) formation. To overcome these problems, an application of low NOx oxy-fuel burner and recycling of a part of off-gas to combustion chamber have been suggested
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Oxygen enrichment incineration
Energy Technology Data Exchange (ETDEWEB)
Kim, Jeong Guk; Yang, Hee Chul; Park, Geun Il; Kim, Joon Hyung
2000-10-01
Oxygen enriched combustion technology has recently been used in waste incineration. To apply the oxygen enrichment on alpha-bearing waste incineration, which is being developed, a state-of-an-art review has been performed. The use of oxygen or oxygen-enriched air instead of air in incineration would result in increase of combustion efficiency and capacity, and reduction of off-gas product. Especially, the off-gas could be reduced below a quarter, which might reduce off-gas treatment facilities, and also increase an efficiency of off-gas treatment. However, the use of oxygen might also lead to local overheating and high nitrogen oxides (NOx) formation. To overcome these problems, an application of low NOx oxy-fuel burner and recycling of a part of off-gas to combustion chamber have been suggested.
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Perovskite-related oxide materials for oxygen-permeable electrochemical membrans
Naumovich, E. N.; Yaremchenko, A. A.; Viskup, A. P.; Kharton, V. V.
2003-01-01
This brief review is focused on the studies of mixed ionic-electronic conductors on the basis of lanthanum gallate doped with transition metal cations in the В sublattice. The substitution of gallium with iron, cobalt or nickel results in greater electronic conductivity, simultaneously keeping high level of the oxy-gen ionic transport. In particular, La0 90Sr0 10Ga0 65Ni0 20Mg0 1503d perovskite exhib-its attractive oxygen permeability, which is quite similar to that of La2Ni04- and (...
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Environmental science: Oceans lose oxygen
Gilbert, Denis
2017-02-01
Oxygen is essential to most life in the ocean. An analysis shows that oxygen levels have declined by 2% in the global ocean over the past five decades, probably causing habitat loss for many fish and invertebrate species. See Letter p.335
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Directory of Open Access Journals (Sweden)
Chang-Soo Kim
2012-06-01
Full Text Available Utilizing a simple fluidic structure, we demonstrate the improved performance of oxidase-based enzymatic biosensors. Electrolysis of water is utilized to generate bubbles to manipulate the oxygen microenvironment close to the biosensor in a fluidic channel. For the proper enzyme reactions to occur, a simple mechanical procedure of manipulating bubbles was developed to maximize the oxygen level while minimizing the pH change after electrolysis. The sensors show improved sensitivities based on the oxygen dependency of enzyme reaction. In addition, this oxygen-rich operation minimizes the ratio of electrochemical interference signal by ascorbic acid during sensor operation (i.e., amperometric detection of hydrogen peroxide. Although creatinine sensors have been used as the model system in this study, this method is applicable to many other biosensors that can use oxidase enzymes (e.g., glucose, alcohol, phenol, etc. to implement a viable component for in-line fluidic sensor systems.
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Liu, Jie; Liu, Yang; Ren, Li-Hua; Li, Li; Wang, Zhen; Liu, Shan-Shan; Li, Su-Zhi; Cao, Tie-Sheng
2016-08-01
To assess racial, sexual, and regional differences in cerebral hemodynamic response to high altitude (HA, 3658 m). We performed cross-sectional comparisons on total cerebral blood flow (TCBF = sum of bilateral internal carotid and vertebral arterial blood flows = QICA + QVA), total cerebrovascular resistance (TCVR), total cerebral oxygen delivery (TCOD) and QVA/TCBF (%), among six groups of young healthy subjects: Tibetans (2-year staying) and Han (Han Chinese) at sea level, Han (2-day, 1-year and 5-year) and Tibetans at HA. Bilateral ICA and VA diameters and flow velocities were derived from duplex ultrasonography; and simultaneous measurements of arterial pressure, oxygen saturation, and hemoglobin concentration were conducted. Neither acute (2-day) nor chronic (>1 year) responses showed sex differences in Han, except that women showed lower TCOD compared with men. Tibetans and Han exhibited different chronic responses (percentage alteration relative to the sea-level counterpart value) in TCBF (-17% vs. 0%), TCVR (22% vs. 12%), TCOD (0% vs. 10%) and QVA/TCBF (0% vs. 2.4%, absolute increase), with lower resting TCOD found in SL- and HA-Tibetans. Our findings indicate racial but not sex differences in cerebral hemodynamic adaptations to HA, with Tibetans (but not Han) demonstrating an altitude-related change of CBF distribution.
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International Nuclear Information System (INIS)
Kossyi, I.A.; Silakov, V.P.; Tarasova, N.M.
2001-01-01
Results are presented from experimental studies of the destruction of chlorofluorocarbon (CF 2 Cl 2 ) molecules in a methane-oxygen (air) gas mixture whose combustion is initiated by a high-current slipping surface discharge. It is found that a three-component CH 4 + O 2 (air)+ CF 2 Cl 2 gas mixture (even with a considerable amount of the third component) demonstrates properties of explosive combustion involving chain reactions that are typical of two-component CH 4 + O 2 mixtures. Experiments show the high degree of destruction (almost complete decomposition) of chlorofluorocarbons contained in the mixture during one combustion event. The combustion dynamics is studied. It is shown that the combustion initiated by a slipping surface discharge has a number of characteristic features that make it impossible to identify the combustion dynamics with the formation of a combustion or detonation wave. The features of the effects observed can be related to intense UV radiation produced by a pulsed high-current surface discharge
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A microfluidic cell culture array with various oxygen tensions.
Peng, Chien-Chung; Liao, Wei-Hao; Chen, Ying-Hua; Wu, Chueh-Yu; Tung, Yi-Chung
2013-08-21
Oxygen tension plays an important role in regulating various cellular functions in both normal physiology and disease states. Therefore, drug testing using conventional in vitro cell models under normoxia often possesses limited prediction capability. A traditional method of setting an oxygen tension in a liquid medium is by saturating it with a gas mixture at the desired level of oxygen, which requires bulky gas cylinders, sophisticated control, and tedious interconnections. Moreover, only a single oxygen tension can be tested at the same time. In this paper, we develop a microfluidic cell culture array platform capable of performing cell culture and drug testing under various oxygen tensions simultaneously. The device is fabricated using an elastomeric material, polydimethylsiloxane (PDMS) and the well-developed multi-layer soft lithography (MSL) technique. The prototype device has 4 × 4 wells, arranged in the same dimensions as a conventional 96-well plate, for cell culture. The oxygen tensions are controlled by spatially confined oxygen scavenging chemical reactions underneath the wells using microfluidics. The platform takes advantage of microfluidic phenomena while exhibiting the combinatorial diversities achieved by microarrays. Importantly, the platform is compatible with existing cell incubators and high-throughput instruments (liquid handling systems and plate readers) for cost-effective setup and straightforward operation. Utilizing the developed platform, we successfully perform drug testing using an anti-cancer drug, triapazamine (TPZ), on adenocarcinomic human alveolar basal epithelial cell line (A549) under three oxygen tensions ranging from 1.4% to normoxia. The developed platform is promising to provide a more meaningful in vitro cell model for various biomedical applications while maintaining desired high throughput capabilities.
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Developmental Effects Determine Submaximal Arterial Oxygen Saturation in Peruvian Quechua.
Kiyamu, Melisa; León-Velarde, Fabiola; Rivera-Chira, María; Elías, Gianpietro; Brutsaert, Tom D
2015-06-01
Kiyamu, Melisa, Fabiola León-Velarde, María Rivera-Chira, Gianpietro Elías, and Tom D. Brutsaert. Developmental effects determine submaximal arterial oxygen saturation in Peruvian Quechua. High Alt Med Biol 16, 138-146, 2015.--Andean high altitude natives show higher arterial oxygen saturation (Sao(2)) during exercise in hypoxia, compared to acclimatized sojourners. In order to evaluate the effects of life-long exposure to high altitude on Sao(2), we studied two groups of well-matched, self-identified Peruvian Quechua natives who differed in their developmental exposure to hypoxia before and after a 2-month training period. Male and female volunteers (18-35 years) were recruited in Lima, Peru (150 m). The two groups were: a) Individuals who were born and raised at sea-level (BSL, n=34) and b) Individuals who were born and raised at high altitude (BHA, n=32), but who migrated to sea-level as adults (>16 years old). Exercise testing was conducted using a submaximal exercise protocol in normobaric hypoxia in Lima (BP=750 mmHg, Fio(2)=0.12), in order to measure Sao(2) (%), ventilation (VE L/min) and oxygen consumption (Vo(2), L/min). Repeated-measures ANOVA, controlling for VE/VO(2) (L/min) and sex during the submaximal protocol showed that BHA maintained higher Sao(2) (%) compared to BSL at all workloads before (p=0.005) and after training (p=0.017). As expected, both groups showed a decrease in Sao(2) (%) (p<0.001), as workload increased. Resting Sao(2) levels were not found to be different between groups. The results suggest that developmental exposure to altitude contributes to the maintenance of higher Sao(2) levels during submaximal exercise at hypoxia.
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Directory of Open Access Journals (Sweden)
Alessandra Puddu
2014-01-01
Full Text Available Glucagon-like peptide-1 (GLP-1, an intestinal hormone contributing to glucose homeostasis, is synthesized by proglucagon and secreted from intestinal neuroendocrine cells in response to nutrients. GLP-1 secretion is impaired in type 2 diabetes patients. Here, we aimed at investigating whether diabetic toxic products (glycated serum (GS or high levels of glucose (HG may affect viability, function, and insulin sensitivity of the GLP-1 secreting cell line GLUTag. Cells were cultured for 5 days in presence or absence of different dilutions of GS or HG. GS and HG (alone or in combination increased reactive oxygen species (ROS production and upregulated proglucagon mRNA expression as compared to control medium. Only HG increased total production and release of active GLP-1, while GS alone abrogated secretion of active GLP-1. HG-mediated effects were associated with the increased cell content of the prohormone convertase 1/3 (PC 1/3, while GS alone downregulated this enzyme. HG upregulated Glucokinase (GK and downregulated SYNTHAXIN-1. GS abrogated SYNTHAXIN-1 and SNAP-25. Finally, high doses of GS alone or in combination with HG reduced insulin-mediated IRS-1 phosphorylation. In conclusion, we showed that GS and HG might regulate different pathways of GLP-1 production in diabetes, directly altering the function of neuroendocrine cells secreting this hormone.
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Sarath Kumar, S. R.; Barasheed, Abeer Z.; Alshareef, Husam N.
2013-01-01
We report the evolution of high temperature thermoelectric properties of SrTiO3 thin films doped with Nb and oxygen vacancies. Structure-property relations in this important thermoelectric oxide are elucidated and the variation of transport properties with dopant concentrations is discussed. Oxygen vacancies are incorporated during growth or annealing in Ar/H2 above 800 K. An increase in lattice constant due to the inclusion of Nb and oxygen vacancies is found to result in an increase in carrier density and electrical conductivity with simultaneous decrease in carrier effective mass and Seebeck coefficient. The lattice thermal conductivity at 300 K is found to be 2.22 W m-1 K-1, and the estimated figure of merit is 0.29 at 1000 K. © 2013 American Chemical Society.
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Sarath Kumar, S. R.
2013-08-14
We report the evolution of high temperature thermoelectric properties of SrTiO3 thin films doped with Nb and oxygen vacancies. Structure-property relations in this important thermoelectric oxide are elucidated and the variation of transport properties with dopant concentrations is discussed. Oxygen vacancies are incorporated during growth or annealing in Ar/H2 above 800 K. An increase in lattice constant due to the inclusion of Nb and oxygen vacancies is found to result in an increase in carrier density and electrical conductivity with simultaneous decrease in carrier effective mass and Seebeck coefficient. The lattice thermal conductivity at 300 K is found to be 2.22 W m-1 K-1, and the estimated figure of merit is 0.29 at 1000 K. © 2013 American Chemical Society.
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A Rechargeable High-Temperature Molten Salt Iron-Oxygen Battery.
Peng, Cheng; Guan, Chengzhi; Lin, Jun; Zhang, Shiyu; Bao, Hongliang; Wang, Yu; Xiao, Guoping; Chen, George Zheng; Wang, Jian-Qiang
2018-06-11
The energy and power density of conventional batteries are far lower than their theoretical expectations, primarily because of slow reaction kinetics that are often observed under ambient conditions. Here we describe a low-cost and high-temperature rechargeable iron-oxygen battery containing a bi-phase electrolyte of molten carbonate and solid oxide. This new design merges the merits of a solid-oxide fuel cell and molten metal-air battery, offering significantly improved battery reaction kinetics and power capability without compromising the energy capacity. The as-fabricated battery prototype can be charged at high current density, and exhibits excellent stability and security in the highly charged state. It typically exhibits specific energy, specific power, energy density, and power density of 129.1 Wh kg -1 , 2.8 kW kg -1 , 388.1 Wh L -1 , and 21.0 kW L -1 , respectively, based on the mass and volume of the molten salt. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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High energy lithium-oxygen batteries - Transport barriers and thermodynamics
Das, Shyamal K.
2012-01-01
We show that it is possible to achieve higher energy density lithium-oxygen batteries by simultaneously lowering the discharge overpotential and increasing the discharge capacity via thermodynamic variables alone. By assessing the relative effects of temperature and pressure on the cell discharge profiles, we characterize and diagnose the critical roles played by multiple dynamic processes that have hindered implementation of the lithium-oxygen battery. © 2012 The Royal Society of Chemistry.
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Directory of Open Access Journals (Sweden)
Wael Seliem
Full Text Available Abstract Objective: The objective of this study is to evaluate the hypothesis that use of heliox would result in improvement of gas exchange when used with high flow nasal cannula in infants with RSV acute bronchiolitis. Methods: All patients that met the inclusion criteria were randomized to either heliox (70:30 or air-oxygen mixture 30% via high flow nasal cannula at 8 L/min for a continuous 24 h. Measurements were taken at baseline, after 2 h, and at the end of the 24 h. Results: This prospective study included 48 patients. After 2 h of treatment with heliox, the oxygen saturation and PaO2 significantly improved when compared with the air-oxygen group, 98.3% vs. 92.9%, 62.0 mmHg vs. 43.6 mmHg (p = 0.04 and 0.01, respectively. Furthermore, PaO2/FiO2 ratio was significantly higher in the heliox group when compared with the air-oxygen group, 206.7 vs. 145.3. Nevertheless, CO2 showed better elimination when heliox was used, without significance. MWCA score dropped significantly in the heliox group, 2.2 points vs. 4.0 points in air-oxygen (p = 0.04, 2 h after starting the therapy. Conclusion: Transient improvement of oxygenation in infants with RSV acute bronchiolitis during the initial phase of the therapy is associated with heliox when provided with HFNC, may provide a precious time for other therapeutic agents to work or for the disease to resolve naturally, avoiding other aggressive interventions.
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International Nuclear Information System (INIS)
Cui Shumao; Mattson, Eric C.; Lu, Ganhua; Hirschmugl, Carol; Gajdardziska-Josifovska, Marija; Chen Junhong
2012-01-01
Nanomaterials with controllable morphology and composition are synthesized by a simple one-step vapor condensation process using a mini-arc plasma source. Through systematic investigation of mini-arc reactor parameters, the roles of carrier gas, electrode material, and precursor on producing diverse nanomaterial products are revealed. Desired nanomaterial products, including tungsten oxide nanoparticles (NPs), tungsten oxide nanorods (NRs), tungsten oxide and tin oxide NP mixtures and pure tin dioxide NPs can thus be obtained by tailoring reaction conditions. The amount of oxygen in the reactor is critical to determining the final nanomaterial product. Without any precursor material present, a lower level of oxygen in the reactor favors the production of W 18 O 49 NRs with tungsten as cathode, while a high level of oxygen produces more round WO 3 NPs. With the presence of a precursor material, amorphous particles are favored with a high ratio of argon:oxygen. Oxygen is also found to affect tin oxide crystallization from its amorphous phase in the thermal annealing. Results from this study can be used for guiding gas phase nanomaterial synthesis in the future.
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Bajgar, Robert; Kolarova, Hana; Bolek, Lukas; Binder, Svatopluk; Pizova, Klara; Hanakova, Adela
2014-08-01
Photodynamic therapy (PDT) is linked with oxidative damage of biomolecules causing significant impairment of essential cellular functions that lead to cell death. It is the reason why photodynamic therapy has found application in treatment of different oncological, cardiovascular, skin and eye diseases. Efficacy of PDT depends on combined action of three components; sensitizer, light and oxygen. In the present study, we examined whether higher partial pressure of oxygen increases lethality in HeLa cell lines exposed to light in the presence of chloraluminium phthalocyanine disulfonate (ClAlPcS2). ClAlPcS2- sensitized HeLa cells incubated under different oxygen conditions were exposed to PDT. Production of singlet oxygen ((1)O2) and other forms of reactive oxygen species (ROS) as well as changes in mitochondrial membrane potential were determined by appropriately sensitive fluorescence probes. The effect of PDT on HeLa cell viability under different oxygen conditions was quantified using the standard methylthiazol tetrazolium (MTT) test. At the highest oxygen concentration of 28 ± 2 mg/l HeLa cells were significantly more sensitive to light-activated ClAlPcS2 (EC50=0.29 ± 0.05 μM) in comparison to cells incubated at lower oxygen concentrations of 8 ± 0.5 and 0.5 ± 0.1 mg/l, where the half maximal effective concentration was 0.42 ± 0.06 μM and 0.94 ± 0.14 μM, respectively. Moreover, we found that the higher presence of oxygen is accompanied with higher production of singlet oxygen, a higher rate of type II photodynamic reactions, and a significant drop in the mitochondrial membrane potential. These results demonstrate that the photodynamic effect in cervical cancer cells utilizing ClAlPcS2 significantly depends on oxygen level. Copyright© 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.
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The oxygen effect and cellular adaptation
International Nuclear Information System (INIS)
Meshcherikova, V.V.; Vajnson, A.A.; Yarmonenko, S.P.
1979-01-01
The radiomodifying effect of oxygen was shown to depend on the level of cellular oxygenation prior to irradiation. Acute hypoxia created at the time of irradiation protects previously normally oxygenated cells with DMF approximately 1.4 times larger than that of cells cultured for 24 hours under conditions of mild hypoxia. It is suggested that a decrease in the radioprotective effect of acute hypoxia on chronically hypoxic cells is correlated with an appreciable decrease in the rate of oxygen consumption by these cells, due to which the oxygen concentration near the intracellular targets in chronically hypoxic cells may be higher than in normal cells under conditions of poor oxygenation
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International Nuclear Information System (INIS)
Akashi, Masatsune; Kawamoto, Teruaki
1978-01-01
The effect of molybdenum addition on the SCC susceptibility of sensitized stainless steel in oxygenated high temperature water has been studied through the creviced bent beam SCC test (CBB test) and A262E intergranular corrosion test. The molybdenum addition improved the SCC susceptibility of sensitized stainless steels in oxygenated high temperature water not only by delaying the sensitization at lower temperatures but also by increasing the material resistance to the SCC under a given degree of sensitization. These laboratory test results reveal that the molybdenum addition is quite beneficial for improving the SCC susceptibility of stainless steel pipe weld joints in boiling water reactor environment. (auth.)
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Johnson, Sean C.; Large, Ross R.; Coveney, Raymond M.; Kelley, Karen D.; Slack, John F.; Steadman, Jeffrey A.; Gregory, Daniel D.; Sack, Patrick J.; Meffre, Sebastien
2017-08-01
Highly metalliferous black shales (HMBS) are enriched in organic carbon and a suite of metals, including Ni, Se, Mo, Ag, Au, Zn, Cu, Pb, V, As, Sb, Se, P, Cr, and U ± PGE, compared to common black shales, and are distributed at particular times through Earth history. They constitute an important future source of metals. HMBS are relatively thin units within thicker packages of regionally extensive, continental margin or intra-continental marine shales that are rich in organic matter and bio-essential trace elements. Accumulation and preservation of black shales, and the metals contained within them, usually require low-oxygen or euxinic bottom waters. However, whole-rock redox proxies, particularly Mo, suggest that HMBS may have formed during periods of elevated atmosphere pO2. This interpretation is supported by high levels of nutrient trace elements within these rocks and secular patterns of Se and Se/Co ratios in sedimentary pyrite through Earth history, with peaks occurring in the middle Paleoproterozoic, Early Cambrian to Early Ordovician, Middle Devonian, Middle to late Carboniferous, Middle Permian, and Middle to Late Cretaceous, all corresponding with time periods of HMBS deposition. This counter-intuitive relationship of strongly anoxic to euxinic, localized seafloor conditions forming under an atmosphere of peak oxygen concentrations is proposed as key to the genesis of HMBS. The secular peaks and shoulders of enriched Se in sedimentary pyrite through time correlate with periods of tectonic plate collision, which resulted in high nutrient supply to the oceans and consequently maximum productivity accompanying severe drawdown into seafloor muds of C, S, P, and nutrient trace metals. The focused burial of C and S over extensive areas of the seafloor, during these anoxic to euxinic periods, likely resulted in an O2 increase in the atmosphere, causing short-lived peaks in pO2 that coincide with the deposition of HMBS. As metals become scarce, particularly Mo
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Holloway, Paul H; Pritchard, David G
2017-08-01
The characteristics of the vacuum used in a low atmospheric pressure stunning system to stun (render unconscious) poultry prior to slaughter are described. A vacuum chamber is pumped by a wet screw compressor. The vacuum pressure is reduced from ambient atmospheric pressure to an absolute vacuum pressure of ∼250 Torr (∼33 kPa) in ∼67 sec with the vacuum gate valve fully open. At ∼250 Torr, the sliding gate valve is partially closed to reduce effective pumping speed, resulting in a slower rate of decreasing pressure. Ambient temperature affects air density and water vapor pressure and thereby oxygen levels and the time at the minimum total pressure of ∼160 Torr (∼21 kPa) is varied from ∼120 to ∼220 sec to ensure an effective stun within the 280 seconds of each cycle. The reduction in total pressure results in a gradual reduction of oxygen partial pressure that was measured by a solid-state electrochemical oxygen sensor. The reduced oxygen pressure leads to hypoxia, which is recognized as a humane method of stunning poultry. The system maintains an oxygen concentration of air always reduces the oxygen concentrations to a value lower than in dry air. The partial pressure of water and oxygen were found to depend on the pump down parameters due to the formation of fog in the chamber and desorption of water from the birds and the walls of the vacuum chamber. © The Author 2017. Published by Oxford University Press on behalf of Poultry Science Association.
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Oxygen and oxidative stress in the perinatal period
Directory of Open Access Journals (Sweden)
Isabel Torres-Cuevas
2017-08-01
Full Text Available Fetal life evolves in a hypoxic environment. Changes in the oxygen content in utero caused by conditions such as pre-eclampsia or type I diabetes or by oxygen supplementation to the mother lead to increased free radical production and correlate with perinatal outcomes.In the fetal-to-neonatal transition asphyxia is characterized by intermittent periods of hypoxia ischemia that may evolve to hypoxic ischemic encephalopathy associated with neurocognitive, motor, and neurosensorial impairment. Free radicals generated upon reoxygenation may notably increase brain damage. Hence, clinical trials have shown that the use of 100% oxygen given with positive pressure in the airways of the newborn infant during resuscitation causes more oxidative stress than using air, and increases mortality.Preterm infants are endowed with an immature lung and antioxidant system. Clinical stabilization of preterm infants after birth frequently requires positive pressure ventilation with a gas admixture that contains oxygen to achieve a normal heart rate and arterial oxygen saturation. In randomized controlled trials the use high oxygen concentrations (90% to 100% has caused more oxidative stress and clinical complications that the use of lower oxygen concentrations (30–60%. A correlation between the amount of oxygen received during resuscitation and the level of biomarkers of oxidative stress and clinical outcomes was established. Thus, based on clinical outcomes and analytical results of oxidative stress biomarkers relevant changes were introduced in the resuscitation policies. However, it should be underscored that analysis of oxidative stress biomarkers in biofluids has only been used in experimental and clinical research but not in clinical routine. The complexity of the technical procedures, lack of automation, and cost of these determinations have hindered the routine use of biomarkers in the clinical setting. Overcoming these technical and economical difficulties
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Spectroscopic Determination of Trace Contaminants in High-Purity Oxygen
Hornung, Steven
2013-01-01
Oxygen used for extravehicular activities (EVAs) must be free of contaminants because a difference in a few tenths of a percent of argon or nitrogen content can mean significant reduction in available EVA time. These inert gases build up in the extravehicular mobility unit because they are not metabolized or scrubbed from the atmosphere. A prototype optical emission technique capable of detecting argon and nitrogen below 0.1% in oxygen has been developed. This instrument uses a glow discharge in reduced-pressure gas to produce atomic emission from the species present. Because the atomic emission lines from oxygen, nitrogen, and argon are discrete, and in many cases well-separated, trace amounts of argon and nitrogen can be detected in the ultraviolet and visible spectrum. This is a straightforward, direct measurement of the target contaminants, and may lend itself to a device capable of on-orbit verification of oxygen purity. A glow discharge is a plasma formed in a low-pressure (1 to 10 Torr) gas cell between two electrodes. Depending on the configuration, voltages ranging from 200 V and above are required to sustain the discharge. In the discharge region, the gas is ionized and a certain population is in the excited state. Light is produced by the transitions from the excited states formed in the plasma to the ground state. The spectrum consists of discrete, narrow emission lines for the atomic species, and broader peaks that may appear as a manifold for molecular species such as O2 and N2, the wavelengths and intensities of which are a characteristic of each atom. The oxygen emission is dominated by two peaks at 777 and 844 nm.
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High-level language computer architecture
Chu, Yaohan
1975-01-01
High-Level Language Computer Architecture offers a tutorial on high-level language computer architecture, including von Neumann architecture and syntax-oriented architecture as well as direct and indirect execution architecture. Design concepts of Japanese-language data processing systems are discussed, along with the architecture of stack machines and the SYMBOL computer system. The conceptual design of a direct high-level language processor is also described.Comprised of seven chapters, this book first presents a classification of high-level language computer architecture according to the pr
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International Nuclear Information System (INIS)
Bray, G.R.
1976-01-01
The main emphasis of the work in the area of partitioning transuranic elements from waste has been in the area of high-level liquid waste. But there are ''other-than-high-level wastes'' generated by the back end of the nuclear fuel cycle that are both large in volume and contaminated with significant quantities of transuranic elements. The combined volume of these other wastes is approximately 50 times that of the solidified high-level waste. These other wastes also contain up to 75% of the transuranic elements associated with waste generated by the back end of the fuel cycle. Therefore, any detailed evaluation of partitioning as a viable waste management option must address both high-level wastes and ''other-than-high-level wastes.''
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Prospects for detecting oxygen, water, and chlorophyll on an exo-Earth.
Brandt, Timothy D; Spiegel, David S
2014-09-16
The goal of finding and characterizing nearby Earth-like planets is driving many NASA high-contrast flagship mission concepts, the latest of which is known as the Advanced Technology Large-Aperture Space Telescope (ATLAST). In this article, we calculate the optimal spectral resolution R = λ/δλ and minimum signal-to-noise ratio per spectral bin (SNR), two central design requirements for a high-contrast space mission, to detect signatures of water, oxygen, and chlorophyll on an Earth twin. We first develop a minimally parametric model and demonstrate its ability to fit synthetic and observed Earth spectra; this allows us to measure the statistical evidence for each component's presence. We find that water is the easiest to detect, requiring a resolution R ≳ 20, while the optimal resolution for oxygen is likely to be closer to R = 150, somewhat higher than the canonical value in the literature. At these resolutions, detecting oxygen will require approximately two times the SNR as water. Chlorophyll requires approximately six times the SNR as oxygen for an Earth twin, only falling to oxygen-like levels of detectability for a low cloud cover and/or a large vegetation covering fraction. This suggests designing a mission for sensitivity to oxygen and adopting a multitiered observing strategy, first targeting water, then oxygen on the more favorable planets, and finally chlorophyll on only the most promising worlds.
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Oxygen--a limiting factor for brain recovery.
Hadanny, Amir; Efrati, Shai
2015-09-01
Effective brain metabolism is highly dependent on a narrow therapeutic window of oxygen. In major insults to the brain (e.g., intracerebral hemorrhage), a slight decrease in oxygen supply, as occurs in a hypobaric environment at high altitude, has devastating effects on the injured brain tissue. Conversely, increasing brain oxygenation, by the use of hyperbaric oxygen therapy, can improve brain metabolism and its dependent regenerative processes.
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Oxygen - a limiting factor for brain recovery
Hadanny, Amir; Efrati, Shai
2015-01-01
Effective brain metabolism is highly dependent on a narrow therapeutic window of oxygen. In major insults to the brain (e.g., intracerebral hemorrhage), a slight decrease in oxygen supply, as occurs in a hypobaric environment at high altitude, has devastating effects on the injured brain tissue. Conversely, increasing brain oxygenation, by the use of hyperbaric oxygen therapy, can improve brain metabolism and its dependent regenerative processes.
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A rechargeable carbon-oxygen battery
DEFF Research Database (Denmark)
2014-01-01
The invention relates to a rechargeable battery and a method to operate a rechargeable battery having high efficiency and high energy density for storing energy. The battery stores electrical energy in the bonds of carbon and oxygen atoms by converting carbon dioxide into solid carbon and oxygen....
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DEFF Research Database (Denmark)
Bolumar Garcia, Jose Tomas; Lapena Gomez, David; Skibsted, Leif Horsfelt
2016-01-01
Three different packaging systems: vacuum packaging, rosemary active packaging, and oxygen scavenger packaging were compared for their ability to counteract lipid oxidation in pork patties upon storage at 5 °C for 60 days following high pressure processing (HPP) (700 MPa, 10 min, 5 °C). Lipid...... oxidation was studied at the surface and the inner part by measuring secondary lipid oxidation products (TBARs) and the tendency to form radicals by electron spin resonance (ESR) spectroscopy. Lipid oxidation was lower in the inner part than at the surface for all three packaging systems. Rosemary active...... packaging was the most effective method to protect pork patties from the HPP-induced lipid oxidation, while oxygen scavenger packaging was not effective since residual oxygen remained in the package in the initial period of storage. The kinetics of the oxygen trapping by oxygen scavengers appears...
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Oxygen sensitive polymeric nanocapsules for optical dissolved oxygen sensors
Sun, Zhijuan; Cai, Chenxin; Guo, Fei; Ye, Changhuai; Luo, Yingwu; Ye, Shuming; Luo, Jianchao; Zhu, Fan; Jiang, Chunyue
2018-04-01
Immobilization of the oxygen-sensitive probes (OSPs) in the host matrix greatly impacts the performance and long-term usage of the optical dissolved oxygen (DO) sensors. In this work, fluorescent dyes, as the OSPs, were encapsulated with a crosslinked fluorinated polymer shell by interfacial confined reversible addition fragmentation chain transfer miniemulsion polymerization to fabricate oxygen sensitive polymeric nanocapsules (NCs). The location of fluorescent dyes and the fluorescent properties of the NCs were fully characterized by fourier transform infrared spectrometer, x-ray photoelectron spectrometer and fluorescent spectrum. Dye-encapsulated capacity can be precisely tuned from 0 to 1.3 wt% without self-quenching of the fluorescent dye. The crosslinked fluorinated polymer shell is not only extremely high gas permeability, but also prevents the fluorescent dyes from leakage in aqueous as well as in various organic solvents, such as ethanol, acetone and tetrahydrofuran (THF). An optical DO sensor based on the oxygen sensitive NCs was fabricated, showing high sensitivity, short response time, full reversibility, and long-term operational stability of online monitoring DO. The sensitivity of the optical DO sensor is 7.02 (the ratio of the response value in fully deoxygenated and saturated oxygenated water) in the range 0.96-14.16 mg l-1 and the response time is about 14.3 s. The sensor’s work curve was fit well using the modified Stern-Volmer equation by two-site model, and its response values are hardly affected by pH ranging from 2 to 12 and keep constant during continuous measurement for 3 months. It is believed that the oxygen sensitive polymeric NCs-based optical DO sensor could be particularly useful in long-term online DO monitoring in both aqueous and organic solvent systems.
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Palla, A D; Zimmerman, J W; Woodard, B S; Carroll, D L; Verdeyen, J T; Lim, T C; Solomon, W C
2007-07-26
Laser oscillation at 1315 nm on the I(2P1/2)-->I(2P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1Delta) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels of complexity to the singlet oxygen generator (SOG) kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. The advanced model BLAZE-IV has been introduced to study the energy-transfer laser system dynamics and kinetics. Levels of singlet oxygen, oxygen atoms, and ozone are measured experimentally and compared with calculations. The new BLAZE-IV model is in reasonable agreement with O3, O atom, and gas temperature measurements but is under-predicting the increase in O2(a1Delta) concentration resulting from the presence of NO in the discharge and under-predicting the O2(b1Sigma) concentrations. A key conclusion is that the removal of oxygen atoms by NOX species leads to a significant increase in O2(a1Delta) concentrations downstream of the discharge in part via a recycling process; however, there are still some important processes related to the NOX discharge kinetics that are missing from the present modeling. Further, the removal of oxygen atoms dramatically inhibits the production of ozone in the downstream kinetics.
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Hitzfeld, Kristina L; Gehre, Matthias; Richnow, Hans-Hermann
2017-05-01
In this study conversion conditions for oxygen gas chromatography high temperature conversion (HTC) isotope ratio mass spectrometry (IRMS) are characterised using qualitative mass spectrometry (IonTrap). It is shown that physical and chemical properties of a given reactor design impact HTC and thus the ability to accurately measure oxygen isotope ratios. Commercially available and custom-built tube-in-tube reactors were used to elucidate (i) by-product formation (carbon dioxide, water, small organic molecules), (ii) 2nd sources of oxygen (leakage, metal oxides, ceramic material), and (iii) required reactor conditions (conditioning, reduction, stability). The suitability of the available HTC approach for compound-specific isotope analysis of oxygen in volatile organic molecules like methyl tert-butyl ether is assessed. Main problems impeding accurate analysis are non-quantitative HTC and significant carbon dioxide by-product formation. An evaluation strategy combining mass spectrometric analysis of HTC products and IRMS 18 O/ 16 O monitoring for future method development is proposed.
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Mcdonald, Gary H.
1988-01-01
The Space Shuttle Main Engine (SSME) is basically comprised of a combustion chamber and nozzle, high and low pressure oxygen turbopumps and high and low pressure fuel turbopumps. In the current configuration, the high pressure fuel (HPTFP) and high pressure oxygen turbopumps (HPOTP) have experienced a history of ball bearing wear. The wear problem can be attributed to numerous factors including the hydrodynamic axial and radial loads caused by the flow of liquid oxygen and liquid hydrogen through the turbopump impellers and turbine. Also, friction effects between the rolling elements, races, and cage can create thermally induced bearing geometry changes. To alleviate some of the current configuration problems, an alternate turbopump development (ATD) was proposed. However, the ATD HPOTP and HPTFP are constrained to operate interchangeably with the current turbopumps, thus, the operation conditions must be similar. The ATD configuration features a major change in bearings used to support the integrated shaft, impeller, and turbine system. A single ball and single roller will replace the pump-end and turbine and duplex ball bearings. The Shaft-Bearing-Thermal (SHABERTH) computer code was used to model the ATD HPOTP and ATD HPFTP configurations. A two bearing model was used to simulate the HPOTP and HPFTP bearings and shaft geometry. From SHABERTH, a comparison of bearing reaction loads, frictional heat generation rates, and Hertz contact stresses will be attempted with analysis at the 109 percent and 65 percent power levels.
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La2CuO4+δ: Synthesis under high oxygen pressure and study of phase relations and energetics
International Nuclear Information System (INIS)
Rapp, R.P.; Mehta, A.; DiCarlo, J.; Navrotsky, A.
1994-01-01
High oxygen pressures have been achieved in a piston-cylinder apparatus using a double capsule assembly consisting of a sealed outer Au capsule, containing an oxygen source (KMnO 4 ), and an inner, open Pt capsule containing the sample. Using this technique, La 2 CuO 4 was annealed at 800 degree C, 5--25 kbar for 2--4 h. Transposed temperature drop calorimetry at 704 degree C was used to determine the enthalpy of oxidation, and weight loss measurements characterized the oxygen nonstoichiometry, δ, in La 2 CuO 4+δ , in the high-pressure, oxygen annealed samples. For samples analyzed at room temperature, x-ray diffraction measurements show that beyond δ∼0.10--0.13, additional oxygen is accommodated in a perovskite-like LaCuO 3-α phase. An analysis of the thermochemical measurements indicates that the nature of holes in La 2 CuO 4+δ could change in the range of δ∼0.03--0.06. 16,17 It is further suggested that the observed change in the thermochemical behavior in the range of δ∼0.01--0.06 could be the driving influence behind the spinodal decomposition of La 2 CuO 4+δ at low temperatures (Dabrowski et al. 10 )
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Li, Zhuo; Gao, Chunjin; Wang, Yanxue; Liu, Fujia; Ma, Linlin; Deng, Changlei; Niu, Ko-Chi; Lin, Mao-Tsun; Wang, Chen
2011-09-01
Hyperbaric oxygen preconditioning (HBO₂P + HAE) has been found to be beneficial in preventing the occurrence of ischemic damage to brain, spinal cord, heart, and liver in several disease models. In addition, pulmonary inflammation and edema are associated with a marked reduction in the expression levels of both aquaporin (AQP) 1 and AQP5 in the lung. Here, the aims of this study are first to ascertain whether acute lung injury can be induced by simulated high altitude in rats and second to assess whether HBO2P + HAE is able to prevent the occurrence of the proposed high altitude-induced ALI. Rats were randomly divided into the following three groups: the normobaric air (NBA; 21% O₂ at 1 ATA) group, the HBO₂P + high altitude exposure (HAE) group, and the NBA + HAE group. In HBO₂P + HAE group, animals received 100% O₂ at 2.0 ATA for 1 hour per day, for five consecutive days. In HAE groups, animals were exposed to a simulated HAE of 6,000 m in a hypobaric chamber for 24 hours. Right after being taken out to the ambient, animals were anesthetized generally and killed and thoroughly exsanguinated before their lungs were excised en bloc. The lungs were used for both histologic and molecular evaluation and analysis. In NBA + HAE group, the animals displayed higher scores of alveolar edema, neutrophil infiltration, and hemorrhage compared with those of NBA controls. In contrast, the levels of both AQP1 and AQP5 proteins and mRNA expression in the lung in the NBA + HAE group were significantly lower than those of NBA controls. However, the increased lung injury scores and the decreased levels of both AQP1 and AQP5 proteins and mRNA expression in the lung caused by HAE was significantly reduced by HBO₂P + HAE. Our results suggest that high altitude pulmonary injury may be prevented by HBO2P + HAE in rats.
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Directory of Open Access Journals (Sweden)
Songyue Yin
Full Text Available Mitochondria are the primary organelles that consume oxygen and provide energy for cellular activities. To investigate the mitochondrial mechanisms underlying adaptation to extreme oxygen conditions, we generated Drosophila strains that could survive in low- or high-oxygen environments (LOF or HOF, respectively, examined their mitochondria at the ultrastructural level via transmission electron microscopy, studied the activity of their respiratory chain complexes, and quantitatively analyzed the protein abundance responses of the mitochondrial proteomes using Isobaric tag for relative and absolute quantitation (iTRAQ. A total of 718 proteins were identified with high confidence, and 55 and 75 mitochondrial proteins displayed significant differences in abundance in LOF and HOF, respectively, compared with the control flies. Importantly, these differentially expressed mitochondrial proteins are primarily involved in respiration, calcium regulation, the oxidative response, and mitochondrial protein translation. A correlation analysis of the changes in the levels of the mRNAs corresponding to differentially regulated mitochondrial proteins revealed two sets of proteins with different modes of regulation (transcriptional vs. post-transcriptional in both LOF and HOF. We believe that these findings will not only enhance our understanding of the mechanisms underlying adaptation to extreme oxygen conditions in Drosophila but also provide a clue in studying human disease induced by altered oxygen tension in tissues and cells.
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Carbon-hydrogen defects with a neighboring oxygen atom in n-type Si
Gwozdz, K.; Stübner, R.; Kolkovsky, Vl.; Weber, J.
2017-07-01
We report on the electrical activation of neutral carbon-oxygen complexes in Si by wet-chemical etching at room temperature. Two deep levels, E65 and E75, are observed by deep level transient spectroscopy in n-type Czochralski Si. The activation enthalpies of E65 and E75 are obtained as EC-0.11 eV (E65) and EC-0.13 eV (E75). The electric field dependence of their emission rates relates both levels to single acceptor states. From the analysis of the depth profiles, we conclude that the levels belong to two different defects, which contain only one hydrogen atom. A configuration is proposed, where the CH1BC defect, with hydrogen in the bond-centered position between neighboring C and Si atoms, is disturbed by interstitial oxygen in the second nearest neighbor position to substitutional carbon. The significant reduction of the CH1BC concentration in samples with high oxygen concentrations limits the use of this defect for the determination of low concentrations of substitutional carbon in Si samples.
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Hyperbaric oxygen preconditioning protects against traumatic brain injury at high altitude.
Hu, S L; Hu, R; Li, F; Liu, Z; Xia, Y Z; Cui, G Y; Feng, H
2008-01-01
Recent studies have shown that preconditioning with hyperbaric oxygen (HBO) can reduce ischemic and hemorrhagic brain injury. We investigated effects of HBO preconditioning on traumatic brain injury (TBI) at high altitude and examined the role of matrix metalloproteinase-9 (MMP-9) in such protection. Rats were randomly divided into 3 groups: HBO preconditioning group (HBOP; n = 13), high-altitude group (HA; n = 13), and high-altitude sham operation group (HASO; n = 13). All groups were subjected to head trauma by weight-drop device, except for HASO group. HBOP rats received 5 sessions of HBO preconditioning (2.5 ATA, 100% oxygen, 1 h daily) and then were kept in hypobaric chamber at 0.6 ATA (to simulate pressure at 4000m altitude) for 3 days before operation. HA rats received control pretreatment (1 ATA, room air, 1 h daily), then followed the same procedures as HBOP group. HASO rats were subjected to skull opening only without brain injury. Twenty-four hours after TBI, 7 rats from each group were examined for neurological function and brain water content; 6 rats from each group were killed for analysis by H&E staining and immunohistochemistry. Neurological outcome in HBOP group (0.71 +/- 0.49) was better than HA group (1.57 +/- 0.53; p < 0.05). Preconditioning with HBO significantly reduced percentage of brain water content (86.24 +/- 0.52 vs. 84.60 +/- 0.37; p < 0.01). Brain morphology and structure seen by light microscopy was diminished in HA group, while fewer pathological injuries occurred in HBOP group. Compared to HA group, pretreatment with HBO significantly reduced the number of MMP-9-positive cells (92.25 +/- 8.85 vs. 74.42 +/- 6.27; p < 0.01). HBO preconditioning attenuates TBI in rats at high altitude. Decline in MMP-9 expression may contribute to HBO preconditioning-induced protection of brain tissue against TBI.
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Theory and development of fluorescence-based optochemical oxygen sensors: oxygen optodes.
Opitz, N; Lübbers, D W
1987-01-01
range of PO2 values, resulting in a higher resolution. Use of suitable polymer alloys as indicator matrices can even enhance oxygen sensitivity; therefore, the application of optodes for trace analysis of oxygen might be possible, especially with regard to the application of highly oxygen-sensitive phosphorescent indicators. Finally, owing to the reversibility of fluorescence quenching, monitoring of oxygen by fluorescence optical sensors allows a continuous and remote control of biomedical parameters as well as regulation of biotechnological processes.(ABSTRACT TRUNCATED AT 400 WORDS)
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Sakadzić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A; Mandeville, Emiri T; Srinivasan, Vivek J; Arai, Ken; Ruvinskaya, Svetlana; Devor, Anna; Lo, Eng H; Vinogradov, Sergei A; Boas, David A
2010-09-01
Measurements of oxygen partial pressure (pO(2)) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO(2) measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here we report to our knowledge the first practical in vivo two-photon high-resolution pO(2) measurements in small rodents' cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 microm, sub-second temporal resolution and requires low probe concentration. The properties of the probe allowed for direct high-resolution measurement of cortical extravascular (tissue) pO(2), opening many possibilities for functional metabolic brain studies.
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Sakadžić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A.; Mandeville, Emiri T.; Srinivasan, Vivek J.; Arai, Ken; Ruvinskaya, Svetlana; Devor, Anna; Lo, Eng H.; Vinogradov, Sergei A.; Boas, David A.
2010-01-01
The ability to measure oxygen partial pressure (pO2) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO2 measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here, we report the first practical in vivo two-photon high-resolution pO2 measurements in small rodents’ cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 µm, sub-second temporal resolution and requires low probe concentration. Most importantly, the properties of the probe allowed for the first direct high-resolution measurement of cortical extravascular (tissue) pO2, opening numerous possibilities for functional metabolic brain studies. PMID:20693997
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Yuan, Lixia; Chen, Yaqiong; Song, Chongfu; Ye, Tongqi; Guo, Qingxiang; Zhu, Qingshi; Torimoto, Youshifumi; Li, Quanxin
2008-11-07
A novel approach to produce hydrogen from bio-oil was obtained with high carbon conversion (>90%) and hydrogen yield (>90%) at Tcatalytic reforming of oxygenated-organic compounds over 18%NiO/Al(2)O(3) reforming catalyst; thermal electrons play important promoting roles in the decomposition and reforming of the oxygenated-organic compounds in the bio-oil.
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Rusu, Cristian; Morisi, Rita; Boschetto, Davide; Dharmakumar, Rohan; Tsaftaris, Sotirios A
2014-07-01
This paper aims to identify approaches that generate appropriate synthetic data (computer generated) for cardiac phase-resolved blood-oxygen-level-dependent (CP-BOLD) MRI. CP-BOLD MRI is a new contrast agent- and stress-free approach for examining changes in myocardial oxygenation in response to coronary artery disease. However, since signal intensity changes are subtle, rapid visualization is not possible with the naked eye. Quantifying and visualizing the extent of disease relies on myocardial segmentation and registration to isolate the myocardium and establish temporal correspondences and ischemia detection algorithms to identify temporal differences in BOLD signal intensity patterns. If transmurality of the defect is of interest pixel-level analysis is necessary and thus a higher precision in registration is required. Such precision is currently not available affecting the design and performance of the ischemia detection algorithms. In this work, to enable algorithmic developments of ischemia detection irrespective to registration accuracy, we propose an approach that generates synthetic pixel-level myocardial time series. We do this by 1) modeling the temporal changes in BOLD signal intensity based on sparse multi-component dictionary learning, whereby segmentally derived myocardial time series are extracted from canine experimental data to learn the model; and 2) demonstrating the resemblance between real and synthetic time series for validation purposes. We envision that the proposed approach has the capacity to accelerate development of tools for ischemia detection while markedly reducing experimental costs so that cardiac BOLD MRI can be rapidly translated into the clinical arena for the noninvasive assessment of ischemic heart disease.
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A model for oxygen conservation associated with titration during pediatric oxygen therapy.
Directory of Open Access Journals (Sweden)
Grace Wu
Full Text Available Continuous oxygen treatment is essential for managing children with hypoxemia, but access to oxygen in low-resource countries remains problematic. Given the high burden of pneumonia in these countries and the fact that flow can be gradually reduced as therapy progresses, oxygen conservation through routine titration warrants exploration.To determine the amount of oxygen saved via titration during oxygen therapy for children with hypoxemic pneumonia.Based on published clinical data, we developed a model of oxygen flow rates needed to manage hypoxemia, assuming recommended flow rate at start of therapy, and comparing total oxygen used with routine titration every 3 minutes or once every 24 hours versus no titration.Titration every 3 minutes or every 24 hours provided oxygen savings estimated at 11.7% ± 5.1% and 8.1% ± 5.1% (average ± standard error of the mean, n = 3, respectively. For every 100 patients, 44 or 30 kiloliters would be saved-equivalent to 733 or 500 hours at 1 liter per minute.Ongoing titration can conserve oxygen, even performed once-daily. While clinical validation is necessary, these findings could provide incentive for the routine use of pulse oximeters for patient management, as well as further development of automated systems.
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International Nuclear Information System (INIS)
Gurwitz, Ron; Cohen, Rotem; Shalish, Ilan
2014-01-01
ZnO surfaces adsorb oxygen in the dark and emit CO 2 when exposed to white light, reminiscent of the lungs of living creatures. We find that this exchange of oxygen with the ambient affects the integrity of the ZnO surface. Thus, it forms a basis for several interesting surface phenomena in ZnO, such as photoconductivity, photovoltage, and gas sensing, and has a role in ZnO electrical conduction. Using x-ray photoelectron spectroscopy on ZnO nanowires, we observed a decomposition of ZnO under white light and formation of oxygen-depleted surface, which explains photoconductivity by the electron donation of oxygen vacancies. Our findings suggest that the observed decomposition of the ZnO lattice may only take place due to photon-induced reduction of ZnO by carbon containing molecules (or carbo-photonic reduction), possibly from the ambient gas, accounting in a consistent way for both the reduced demands on the energy required for decomposition and for the observed emission of lattice oxygen in the form of CO 2 . The formation of oxygen-vacancy rich surface is suggested to induce surface delta doping, causing accumulation of electrons at the surface, which accounts for both the increase in conductivity and the flattening of the energy bands. Using surface photovoltage spectroscopy in ultra high vacuum, we monitored changes in the deep level spectrum. We observe a wide optical transition from a deep acceptor to the conduction band, which energy position coincides with the position of the so called “green luminescence” in ZnO. This green transition disappears with the formation of surface oxygen vacancies. Since the oxygen vacancies are donors, while the green transition involves surface acceptors, the results suggest that the initial emission of oxygen originates at the defect sites of the latter, thereby eliminating each other. This suggests that the green transition originates at surface Zn vacancy acceptors. Removing an oxygen atom from a Zn vacancy completes
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Energy Technology Data Exchange (ETDEWEB)
Gurwitz, Ron; Cohen, Rotem; Shalish, Ilan, E-mail: shalish@ee.bgu.ac.il [Ben Gurion University, Beer Sheva 84105 (Israel)
2014-01-21
ZnO surfaces adsorb oxygen in the dark and emit CO{sub 2} when exposed to white light, reminiscent of the lungs of living creatures. We find that this exchange of oxygen with the ambient affects the integrity of the ZnO surface. Thus, it forms a basis for several interesting surface phenomena in ZnO, such as photoconductivity, photovoltage, and gas sensing, and has a role in ZnO electrical conduction. Using x-ray photoelectron spectroscopy on ZnO nanowires, we observed a decomposition of ZnO under white light and formation of oxygen-depleted surface, which explains photoconductivity by the electron donation of oxygen vacancies. Our findings suggest that the observed decomposition of the ZnO lattice may only take place due to photon-induced reduction of ZnO by carbon containing molecules (or carbo-photonic reduction), possibly from the ambient gas, accounting in a consistent way for both the reduced demands on the energy required for decomposition and for the observed emission of lattice oxygen in the form of CO{sub 2}. The formation of oxygen-vacancy rich surface is suggested to induce surface delta doping, causing accumulation of electrons at the surface, which accounts for both the increase in conductivity and the flattening of the energy bands. Using surface photovoltage spectroscopy in ultra high vacuum, we monitored changes in the deep level spectrum. We observe a wide optical transition from a deep acceptor to the conduction band, which energy position coincides with the position of the so called “green luminescence” in ZnO. This green transition disappears with the formation of surface oxygen vacancies. Since the oxygen vacancies are donors, while the green transition involves surface acceptors, the results suggest that the initial emission of oxygen originates at the defect sites of the latter, thereby eliminating each other. This suggests that the green transition originates at surface Zn vacancy acceptors. Removing an oxygen atom from a Zn vacancy
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Oxygen, nitric oxide and articular cartilage
Directory of Open Access Journals (Sweden)
B Fermor
2007-04-01
Full Text Available Molecular oxygen is required for the production of nitric oxide (NO, a pro-inflammatory mediator that is associated with osteoarthritis and rheumatoid arthritis. To date there has been little consideration of the role of oxygen tension in the regulation of nitric oxide production associated with arthritis. Oxygen tension may be particularly relevant to articular cartilage since it is avascular and therefore exists at a reduced oxygen tension. The superficial zone exists at approximately 6% O2, while the deep zone exists at less than 1% O2. Furthermore, oxygen tension can alter matrix synthesis, and the material properties of articular cartilage in vitro.The increase in nitric oxide associated with arthritis can be caused by pro-inflammatory cytokines and mechanical stress. Oxygen tension significantly alters endogenous NO production in articular cartilage, as well as the stimulation of NO in response to both mechanical loading and pro-inflammatory cytokines. Mechanical loading and pro-inflammatory cytokines also increase the production of prostaglandin E2 (PGE2. There is a complex interaction between NO and PGE2, and oxygen tension can alter this interaction. These findings suggest that the relatively low levels of oxygen within the joint may have significant influences on the metabolic activity, and inflammatory response of cartilage as compared to ambient levels. A better understanding of the role of oxygen in the production of inflammatory mediators in response to mechanical loading, or pro-inflammatory cytokines, may aid in the development of strategies for therapeutic intervention in arthritis.
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Petrozziello, Maurizio; Torchio, Fabrizio; Piano, Federico; Giacosa, Simone; Ugliano, Maurizio; Bosso, Antonella; Rolle, Luca
2018-01-01
Since the end of the last century, many works have been carried out to verify the effect of controlled oxygen intake on the chemical and organoleptic characteristics of red wines. In spite of the large number of studies on this subject, oxygen remains a cutting-edge research topic in oenology. Oxygen consumption leads to complex and not univocal changes in wine composition, sometimes positive such as color stabilization, softening of mouthfeel, increase of aroma complexity. However, the variability of these effects, which depend both on the oxygenation conditions and the composition of the wine, require more efforts in this research field to effectively manage wine oxygen exposure. The present study is focused on the evolution of the chemical composition of four different Nebbiolo wines, each of them added with 4 different doses of oxygen (7, 14, 21, and 28 mg/L total intake) during the first month of storage. In this perspective, the evolution over time of wine color and polyphenols was studied. Acetaldehyde, glyceraldehyde and glyoxylic acid were quantified by HPLC. These compounds can play a role in wine aging creating condensed colored and stable products involving anthocyanins with or without tannins. Moreover, some volatile aldehydes correlated with oxidized olfactory notes, including methional and (E)-2-alkenals, have been quantified by GC-MS. Overall, during storage a decrease of color intensity, total and free anthocyanins and an increase in polymeric pigments (in particular the contribution to the red color of pigments not-bleachable by SO 2 or dTAT%) and some minor aldehydes was observed. Nevertheless, the differences in color parameters between the samples with different doses of oxygen were modest. These evidences were in contrast with an evident and detectable increase of free acetaldehyde content at increasing doses of oxygen measured after 60 days of storage. The effect of oxygen on color and production of SO 2 non-bleachable pigments during aging
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Petrozziello, Maurizio; Torchio, Fabrizio; Piano, Federico; Giacosa, Simone; Ugliano, Maurizio; Bosso, Antonella; Rolle, Luca
2018-01-01
Since the end of the last century, many works have been carried out to verify the effect of controlled oxygen intake on the chemical and organoleptic characteristics of red wines. In spite of the large number of studies on this subject, oxygen remains a cutting-edge research topic in oenology. Oxygen consumption leads to complex and not univocal changes in wine composition, sometimes positive such as color stabilization, softening of mouthfeel, increase of aroma complexity. However, the variability of these effects, which depend both on the oxygenation conditions and the composition of the wine, require more efforts in this research field to effectively manage wine oxygen exposure. The present study is focused on the evolution of the chemical composition of four different Nebbiolo wines, each of them added with 4 different doses of oxygen (7, 14, 21, and 28 mg/L total intake) during the first month of storage. In this perspective, the evolution over time of wine color and polyphenols was studied. Acetaldehyde, glyceraldehyde and glyoxylic acid were quantified by HPLC. These compounds can play a role in wine aging creating condensed colored and stable products involving anthocyanins with or without tannins. Moreover, some volatile aldehydes correlated with oxidized olfactory notes, including methional and (E)-2-alkenals, have been quantified by GC-MS. Overall, during storage a decrease of color intensity, total and free anthocyanins and an increase in polymeric pigments (in particular the contribution to the red color of pigments not-bleachable by SO2 or dTAT%) and some minor aldehydes was observed. Nevertheless, the differences in color parameters between the samples with different doses of oxygen were modest. These evidences were in contrast with an evident and detectable increase of free acetaldehyde content at increasing doses of oxygen measured after 60 days of storage. The effect of oxygen on color and production of SO2 non-bleachable pigments during aging
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Arbib, Zouhayr; de Godos Crespo, Ignacio; Corona, Enrique Lara; Rogalla, Frank
2017-06-01
Microalgae culture in high rate algae ponds (HRAP) is an environmentally friendly technology for wastewater treatment. However, for the implementation of these systems, a better understanding of the oxygenation potential and the influence of climate conditions is required. In this work, the rates of oxygen production, consumption, and exchange with the atmosphere were calculated under varying conditions of solar irradiance and dilution rate during six months of operation in a real scale unit. This analysis allowed determining the biological response of these dynamic systems. The rates of oxygen consumption measured were considerably higher than the values calculated based on the organic loading rate. The response to light intensity in terms of oxygen production in the bioreactor was described with one of the models proposed for microalgae culture in dense concentrations. This model is based on the availability of light inside the culture and the specific response of microalgae to this parameter. The specific response to solar radiation intensity showed a reasonable stability in spite of the fluctuations due to meteorological conditions. The methodology developed is a useful tool for optimization and prediction of the performance of these systems.
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Temperature effects on hemocyanin oxygen binding in an antarctic cephalopod.
Zielinski, S; Sartoris, F J; Pörtner, H O
2001-02-01
The functional relevance of oxygen transport by hemocyanin of the Antarctic octopod Megaleledone senoi and of the eurythermal cuttlefish Sepia officinalis was analyzed by continuous and simultaneous recordings of changes in pH and hemocyanin oxygen saturation in whole blood at various temperatures. These data were compared to literature data on other temperate and cold-water cephalopods (octopods and giant squid). In S. officinalis, the oxygen affinity of hemocyanin changed at deltaP50/degrees C = 0.12 kPa (pH 7.4) with increasing temperatures; this is similar to observations in temperate octopods. In M. senoi, thermal sensitivity was much smaller (delta log P50/delta pH) increased with increasing temperature in both the cuttlefish and the Antarctic octopod. At low PO2 (1.0 kPa) and pH (7.2), the presence of a large venous oxygen reserve (43% saturation) insensitive to pH reflects reduced pH sensitivity and high oxygen affinity in M. senoi hemocyanin at 0 degrees C. In S. officinalis, this reserve was 19% at pH 7.4, 20 degrees C, and 1.7 kPa O2, a level still higher than in squid. These findings suggest that the lower metabolic rate of octopods and cuttlefish compared to squid is reflected in less pH-dependent oxygen transport. Results of the hemocyanin analysis for the Antarctic octopod were similar to those reported for Vampyroteuthis--an extremely high oxygen affinity supporting a very low metabolic rate. In contrast to findings in cold-adapted giant squid, the minimized thermal sensitivity of oxygen transport in Antarctic octopods will reduce metabolic scope and thereby contribute to their stenothermality.
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International Nuclear Information System (INIS)
Brumboiu, Iulia Emilia; Eriksson, Olle; Brena, Barbara; Ericsson, Leif; Hansson, Rickard; Moons, Ellen
2015-01-01
Fullerenes have been a main focus of scientific research since their discovery due to the interesting possible applications in various fields like organic photovoltaics (OPVs). In particular, the derivative [6,6]-phenyl-C 60 -butyric acid methyl ester (PCBM) is currently one of the most popular choices due to its higher solubility in organic solvents compared to unsubstituted C 60 . One of the central issues in the field of OPVs is device stability, since modules undergo deterioration (losses in efficiency, open circuit voltage, and short circuit current) during operation. In the case of fullerenes, several possibilities have been proposed, including dimerization, oxidation, and impurity related deterioration. We have studied by means of density functional theory the possibility of oxygen adsorption on the C 60 molecular moiety of PCBM. The aim is to provide guidelines for near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) measurements which can probe the presence of atomic or molecular oxygen on the fullerene cage. By analysing several configurations of PCBM with one or more adsorbed oxygen atoms, we show that a joint core level XPS and O1s NEXAFS investigation could be effectively used not only to confirm oxygen adsorption but also to pinpoint the bonding configuration and the nature of the adsorbate
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Oxygen dosing the surface of SrTiO{sub 3}
Energy Technology Data Exchange (ETDEWEB)
Dudy, L.; Scheiderer, P.; Schuetz, P.; Gabel, J.; Buchwald, M.; Sing, M.; Claessen, R. [Physikalisches Institut, Universitaet Wuerzburg (Germany); Denlinger, J.D. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94270 (United States); Schlueter, C.; Lee, T.L. [Diamond Light Source Ltd., Didcot, Oxfordshire (United Kingdom)
2015-07-01
The highly mobile two-dimensional electron system (2DES) on the surface of the insulating SrTiO{sub 3}(STO) offers exciting perspectives for advanced material design. This 2DES resides in a depletion layer caused by oxygen deficiency of the surface. With photoemission spectroscopy, we monitor the appearance of quasi-particle weight (QP) at the Fermi energy and oxygen vacancy induced states in the band gap (IG). Both, QP and IG weight, increase and decrease respectively upon exposure to extreme ultraviolet (XUV) light and in-situ oxygen dosing. By a proper adjustment of oxygen dosing, any intermediate state can be stabilized providing full control over the charge carrier density. From a comparison of the charge carrier concentrations obtained from an analysis of core-level spectra and the Fermi-surface volume, we conclude on a spatially inhomogeneous surface electronic structure with at least two different phases.
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DEFF Research Database (Denmark)
Smeeing, Diederik P J; Hendrikse, Jeroen; Petersen, Esben T
2016-01-01
BACKGROUND: The cerebrovascular reactivity (CVR) results of blood oxygen level-dependent (BOLD) and arterial spin labeling (ASL) MRI studies performed in patients with cerebrovascular disease (steno-occlusive vascular disease or stroke) were systematically reviewed. SUMMARY: Thirty-one articles...... found a significant lower ASL CVR in the ipsilateral hemispheres of patients compared to controls. KEY MESSAGES: This review brings support for a reduced BOLD and ASL CVR in the ipsilateral hemisphere of patients with cerebrovascular disease. We suggest that future studies will be performed in a uniform...... way so reference values can be established and could be used to guide treatment decisions in patients with cerebrovascular disease....
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Groot, S. P. C.; Surki, A. A.; de Vos, R. C. H.; Kodde, J.
2012-01-01
Background and Aims Despite differences in physiology between dry and relative moist seeds, seed ageing tests most often use a temperature and seed moisture level that are higher than during dry storage used in commercial practice and gene banks. This study aimed to test whether seed ageing under dry conditions can be accelerated by storing under high-pressure oxygen. Methods Dry barley (Hordeum vulgare), cabbage (Brassica oleracea), lettuce (Lactuca sativa) and soybean (Glycine max) seeds were stored between 2 and 7 weeks in steel tanks under 18 MPa partial pressure of oxygen. Storage under high-pressure nitrogen gas or under ambient air pressure served as controls. The method was compared with storage at 45 °C after equilibration at 85 % relative humidity and long-term storage at the laboratory bench. Germination behaviour, seedling morphology and tocopherol levels were assessed. Key Results The ageing of the dry seeds was indeed accelerated by storing under high-pressure oxygen. The morphological ageing symptoms of the stored seeds resembled those observed after ageing under long-term dry storage conditions. Barley appeared more tolerant of this storage treatment compared with lettuce and soybean. Less-mature harvested cabbage seeds were more sensitive, as was the case for primed compared with non-primed lettuce seeds. Under high-pressure oxygen storage the tocopherol levels of dry seeds decreased, in a linear way with the decline in seed germination, but remained unchanged in seeds deteriorated during storage at 45 °C after equilibration at 85 % RH. Conclusions Seed storage under high-pressure oxygen offers a novel and relatively fast method to study the physiology and biochemistry of seed ageing at different seed moisture levels and temperatures, including those that are representative of the dry storage conditions as used in gene banks and commercial practice. PMID:22967856
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Groot, S P C; Surki, A A; de Vos, R C H; Kodde, J
2012-11-01
Despite differences in physiology between dry and relative moist seeds, seed ageing tests most often use a temperature and seed moisture level that are higher than during dry storage used in commercial practice and gene banks. This study aimed to test whether seed ageing under dry conditions can be accelerated by storing under high-pressure oxygen. methods: Dry barley (Hordeum vulgare), cabbage (Brassica oleracea), lettuce (Lactuca sativa) and soybean (Glycine max) seeds were stored between 2 and 7 weeks in steel tanks under 18 MPa partial pressure of oxygen. Storage under high-pressure nitrogen gas or under ambient air pressure served as controls. The method was compared with storage at 45 °C after equilibration at 85 % relative humidity and long-term storage at the laboratory bench. Germination behaviour, seedling morphology and tocopherol levels were assessed. The ageing of the dry seeds was indeed accelerated by storing under high-pressure oxygen. The morphological ageing symptoms of the stored seeds resembled those observed after ageing under long-term dry storage conditions. Barley appeared more tolerant of this storage treatment compared with lettuce and soybean. Less-mature harvested cabbage seeds were more sensitive, as was the case for primed compared with non-primed lettuce seeds. Under high-pressure oxygen storage the tocopherol levels of dry seeds decreased, in a linear way with the decline in seed germination, but remained unchanged in seeds deteriorated during storage at 45 °C after equilibration at 85 % RH. Seed storage under high-pressure oxygen offers a novel and relatively fast method to study the physiology and biochemistry of seed ageing at different seed moisture levels and temperatures, including those that are representative of the dry storage conditions as used in gene banks and commercial practice.
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The management of high-level radioactive wastes
International Nuclear Information System (INIS)
Lennemann, Wm.L.
1979-01-01
The definition of high-level radioactive wastes is given. The following aspects of high-level radioactive wastes' management are discussed: fuel reprocessing and high-level waste; storage of high-level liquid waste; solidification of high-level waste; interim storage of solidified high-level waste; disposal of high-level waste; disposal of irradiated fuel elements as a waste
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Li, Xuechun; Li, Dian; Wang, Younian
2016-09-01
A dielectric barrier discharge (DBD) can generate a low-temperature plasma easily at atmospheric pressure and has been investigated for applications in trials in cancer therapy, sterilization, air pollution control, etc. It has been confirmed that reactive oxygen species (ROS) play a key role in the processes. In this work, we use a fluid model to simulate the plasma characteristics for DBD in argon-oxygen mixture. The effects of oxygen concentration on the plasma characteristics have been discussed. The evolution mechanism of ROS has been systematically analyzed. It was found that the ground state oxygen atoms and oxygen molecular ions are the dominated oxygen species under the considered oxygen concentrations. With the oxygen concentration increasing, the densities of electrons, argon atomic ions, resonance state argon atoms, metastable state argon atoms and excited state argon atoms all show a trend of decline. The oxygen molecular ions density is high and little influenced by the oxygen concentration. Ground state oxygen atoms density tends to increase before falling. The ozone density increases significantly. Increasing the oxygen concentration, the discharge mode begins to change gradually from the glow discharge mode to Townsend discharge mode. Project supported by the National Natural Science Foundation of China (Grant No. 11175034).
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Photoacoustic microscopy of cerebral hemodynamic and oxygen-metabolic responses to anesthetics
Cao, Rui; Li, Jun; Ning, Bo; Sun, Naidi; Wang, Tianxiong; Zuo, Zhiyi; Hu, Song
2017-02-01
General anesthetics are known to have profound effects on cerebral hemodynamics and neuronal activities. However, it remains a challenge to directly assess anesthetics-induced hemodynamic and oxygen-metabolic changes from the true baseline under wakefulness at the microscopic level, due to the lack of an enabling technology for high-resolution functional imaging of the awake mouse brain. To address this challenge, we have developed head-restrained photoacoustic microscopy (PAM), which enables simultaneous imaging of the cerebrovascular anatomy, total concentration and oxygen saturation of hemoglobin (CHb and sO2), and blood flow in awake mice. From these hemodynamic measurements, two important metabolic parameters, oxygen extraction fraction (OEF) and the cerebral metabolic rate of oxygen (CMRO2), can be derived. Side-by-side comparison of the mouse brain under wakefulness and anesthesia revealed multifaceted cerebral responses to isoflurane, a volatile anesthetic widely used in preclinical research and clinical practice. Key observations include elevated cerebral blood flow (CBF) and reduced oxygen extraction and metabolism.
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Sakadžić, Sava; Mandeville, Emiri T; Gagnon, Louis; Musacchia, Joseph J; Yaseen, Mohammad A; Yucel, Meryem A; Lefebvre, Joel; Lesage, Frédéric; Dale, Anders M; Eikermann-Haerter, Katharina; Ayata, Cenk; Srinivasan, Vivek J; Lo, Eng H; Devor, Anna; Boas, David A
2014-12-08
What is the organization of cerebral microvascular oxygenation and morphology that allows adequate tissue oxygenation at different activity levels? We address this question in the mouse cerebral cortex using microscopic imaging of intravascular O2 partial pressure and blood flow combined with numerical modelling. Here we show that parenchymal arterioles are responsible for 50% of the extracted O2 at baseline activity, and the majority of the remaining O2 exchange takes place within the first few capillary branches. Most capillaries release little O2 at baseline acting as an O2 reserve that is recruited during increased neuronal activity or decreased blood flow. Our results challenge the common perception that capillaries are the major site of O2 delivery to cerebral tissue. The understanding of oxygenation distribution along arterio-capillary paths may have profound implications for the interpretation of blood-oxygen-level dependent (BOLD) contrast in functional magnetic resonance imaging and for evaluating microvascular O2 delivery capacity to support cerebral tissue in disease.
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DEFF Research Database (Denmark)
Jongberg, Sisse; Wen, Jinzhu; Tørngren, Mari Ann
2014-01-01
The oxidative stability and sensory quality of chicken breast (m. pectoralis) and thigh (m. peroneus longus) stored in high-oxygen modified atmosphere (MAP-O), non-oxygen modified atmosphere (MAP-N), or vacuum for up to 9 days at 5°C were investigated. Protein thiol concentration in breasts and t...
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Compact, High-Accuracy Oxygen Flow Meter, Phase I
National Aeronautics and Space Administration — Life support systems for future space suits will require advanced instrumentation to enable use of the suit for multiple missions. We propose to develop an oxygen...
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Directory of Open Access Journals (Sweden)
Yan Zhao
2017-11-01
Full Text Available In this work, a facile strategy to synthesize oxygen and nitrogen co-doped porous carbon (ONPC is reported by one-step pyrolysis of waste coffee grounds. As-prepared ONPC possesses highly rich micro/mesopores as well as abundant oxygen and nitrogen co-doping, which is applied to sulfur hosts as lithium/sulfur batteries’ appropriate cathodes. In battery testing, the sulfur/oxygen and nitrogen co-doped porous carbon (S/ONPC composite materials reveal a high initial capacity of 1150 mAh·g−1 as well as a reversible capacity of 613 mAh·g−1 after the 100th cycle at 0.2 C. Furthermore, when current density increases to 1 C, a discharge capacity of 331 mAh·g−1 is still attainable. Due to the hierarchical porous framework and oxygen/nitrogen co-doping, the S/ONPC composite exhibits a high utilization of sulfur and good electrochemical performance via the immobilization of the polysulfides through strong chemical binding.
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Oxygen status during haemodialysis. The Cord-Group
DEFF Research Database (Denmark)
Nielsen, A L; Jensen, H Æ; Hegbrant, J
1995-01-01
Hypoxia during haemodialysis, mainly acetate, has been reported several times. In our study we have monitored oxygen status during 258 bicarbonate haemodialyses. A significant drop below 80 mmHg in mean oxygen tension occurred. Mean oxygen saturation reflected this drop but did not reach levels...... below 90%. The mean oxygen concentration was on the whole critical low, though slightly increasing during each haemodialysis session due to ultrafiltration. It is concluded that both hypoxia and hypoxaemia do occur during bicarbonate haemodialysis. To a group of patients generally having limited cardiac...... reserves, a poor oxygen status is a potentially serious complication to haemodialysis. Monitoring oxygen status is thus advisable....
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Directory of Open Access Journals (Sweden)
Suzuki Katsuhiko
2008-10-01
Full Text Available Abstract Background Reactive oxygen species (ROS, including free radicals, oxygen ions, and peroxides, are implicated in cell damage. The objective of this study was to investigate whether the spontaneous production of ROS from neutrophils changes with age and is associated with the conventional inflammatory markers. Results Thirty-seven elderly subjects (median age, 87, range 70–95 years and 22 young subjects (median age, 26, range 21–37 years participated in this study. Circulating levels of C-reactive protein, serum amyloid A, tumor necrosis factor-α, interleukin (IL-1, IL-6, IL-8, monocyte chemotactic protein-1, and heat shock protein (HSP70 were measured with enzyme-linked immunosorbent assays. The N-formyl-methionyl-leucyl-phenylalanine and lipopolysaccharide-stimulated ROS of neutrophils were quantified by flow cytometry. Both spontaneous ROS production and circulating levels of inflammatory markers were higher in the elderly group than in the younger group. In addition, spontaneous ROS production by neutrophils was negatively associated with HSP70 in plasma. We could not find the association between spontaneous ROS production by neutrophils and the other inflammatory markers including cytokines. Conclusion The results suggest that spontaneous ROS production from neutrophils may increase with age and represent the different aspect of age-associated immune dysregulation.
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International Nuclear Information System (INIS)
Chowdhury, D.P.; Pal, S.; Arunachalam, J.; Verma R.; Gangadharan, S.
1992-01-01
40 MeV α-particles have been used to determine oxygen impurity at ppm levels in silicon, copper, and stainless steel, through the radiochemical separation of 18 F from the matrix. The separation of 18 F has been carried out by two techniques, viz. distillation of H 2 SiF 6 and precipitation of KBF 4 and some modification has been applied in the separation, depending on the nature of interferences from the matrix. Instrumental approach was also carried out to determine the oxygen impurity at ≥ 100 ppm in Si matrix because this approach is not possible in Cu and stainless steel samples due to matrix activity. (author) 10 refs.; 1 fig.; 5 tabs
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Detection of Acute Tubular Necrosis Using Blood Oxygenation Level-Dependent (BOLD MRI
Directory of Open Access Journals (Sweden)
Frederic Bauer
2017-12-01
Full Text Available Background/Aims: To date, there is no imaging technique to assess tubular function in vivo. Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI measures tissue oxygenation based on the transverse relaxation rate (R2*. The present study investigates whether BOLD MRI can assess tubular function using a tubule-specific pharmacological maneuver. Methods: Cross sectional study with 28 participants including 9 subjects with ATN-induced acute kidney injury (AKI, 9 healthy controls, and 10 subjects with nephron sparing tumor resection (NSS with clamping of the renal artery serving as a model of ischemia/reperfusion (I/R-induced subclinical ATN (median clamping time 15 min, no significant decrease of eGFR, p=0.14. BOLD MRI was performed before and 5, 7, and 10 min after intravenous administration of 40 mg furosemide. Results: Urinary neutrophil gelatinase-associated lipocalin was significantly higher in ATN-induced AKI and NSS subjects than in healthy controls (p=0.03 and p=0.01, respectively. Before administration of furosemide, absolute medullary R2*, cortical R2*, and medullary/cortical R2* ratio did not significantly differ between ATN-induced AKI vs. healthy controls and between NSS-I/R vs. contralateral healthy kidneys (p>0.05 each. Furosemide led to a significant decrease in the medullary and cortical R2* of healthy subjects and NSS contralateral kidneys (p<0.05 each, whereas there was no significant change of R2* in ATN-induced AKI and the NSS-I/R kidneys (p>0.05 each. Conclusion: BOLD-MRI is able to detect even mild tubular injury but necessitates a tubule-specific pharmacological maneuver, e.g. blocking the Na+-K+-2Cl- transporter by furosemide.
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Limitations of quantitative photoacoustic measurements of blood oxygenation in small vessels
International Nuclear Information System (INIS)
Sivaramakrishnan, Mathangi; Maslov, Konstantin; Zhang, Hao F; Stoica, George; Wang, Lihong V
2007-01-01
We investigate the feasibility of obtaining accurate quantitative information, such as local blood oxygenation level (sO 2 ), with a spatial resolution of about 50 μm from spectral photoacoustic (PA) measurements. The optical wavelength dependence of the peak values of the PA signals is utilized to obtain the local blood oxygenation level. In our in vitro experimental models, the PA signal amplitude is found to be linearly proportional to the blood optical absorption coefficient when using ultrasonic transducers with central frequencies high enough such that the ultrasonic wavelengths are shorter than the light penetration depth into the blood vessels. For an optical wavelength in the 578-596 nm region, with a transducer central frequency that is above 25 MHz, the sensitivity and accuracy of sO 2 inversion is shown to be better than 4%. The effect of the transducer focal position on the accuracy of quantifying blood oxygenation is found to be negligible. In vivo oxygenation measurements of rat skin microvasculature yield results consistent with those from in vitro studies, although factors specific to in vivo measurements, such as the spectral dependence of tissue optical attenuation, dramatically affect the accuracy of sO 2 quantification in vivo
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Santos, Carla Santana; Kowaltowski, Alicia J.; Bertotti, Mauro
2017-01-01
We developed a highly sensitive oxygen consumption scanning microscopy system using platinized platinum disc microelectrodes. The system is capable of reliably detecting single-cell respiration, responding to classical regulators of mitochondrial oxygen consumption activity as expected. Comparisons with commercial multi-cell oxygen detection systems show that the system has comparable errors (if not smaller), with the advantage of being able to monitor inter and intra-cell heterogeneity in ox...
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Overgaard, Johannes; Andersen, Jonas L; Findsen, Anders; Pedersen, Pil B M; Hansen, Kasper; Ozolina, Karlina; Wang, Tobias
2012-10-15
Numerous recent studies convincingly correlate the upper thermal tolerance limit of aquatic ectothermic animals to reduced aerobic scope, and ascribe the decline in aerobic scope to failure of the cardiovascular system at high temperatures. In the present study we investigate whether this 'aerobic scope model' applies to an air-breathing and semi-terrestrial vertebrate Rhinella marina (formerly Bufo marinus). To quantify aerobic scope, we measured resting and maximal rate of oxygen consumption at temperatures ranging from 10 to 40°C. To include potential effects of acclimation, three groups of toads were acclimated chronically at 20, 25 and 30°C, respectively. The absolute difference between resting and maximal rate of oxygen consumption increased progressively with temperature and there was no significant decrease in aerobic scope, even at temperature immediately below the lethal limit (41-42°C). Haematological and cardiorespiratory variables were measured at rest and immediately after maximal activity at benign (30°C) and critically high (40°C) temperatures. Within this temperature interval, both resting and active heart rate increased, and there was no indication of respiratory failure, judged from high arterial oxygen saturation, P(O2) and [Hb(O2)]. With the exception of elevated resting metabolic rate for cold-acclimated toads, we found few differences in the thermal responses between acclimation groups with regard to the cardiometabolic parameters. In conclusion, we found no evidence for temperature-induced cardiorespiratory failure in R. marina, indicating that maintenance of aerobic scope and oxygen transport is unrelated to the upper thermal limit of this air-breathing semi-terrestrial vertebrate.
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Morsing, IE; Tinnevelt, Marcel; Jansen, Nicolaas J.G.; Koomen, E
2015-01-01
High Flow Nasal Cannula oxygen therapy (HFNC) is nowadays widely used at paediatric intensive care units (PICU) to provide a safe and comfortable (warm and humidified) oxygen delivery in children with respiratory distress. At general paediatric wards HFNC is hardly used because intensive observation
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International Nuclear Information System (INIS)
Sakai, Tetsuya; Kuniyoshi, Yuji; Aoki, Wataru; Ezoe, Sho; Endo, Tatsuya; Hoshi, Yoichi
2008-01-01
High-rate deposition of titanium dioxide (TiO 2 ) film was attempted using oxygen plasma assisted reactive evaporation (OPARE) method. Photocatalytic properties of the film were investigated. During the deposition, the substrate temperature was fixed at 400 deg. C. The film deposition rate can be increased by increasing the supply of titanium atoms to the substrate, although oversupply of the titanium atoms causes oxygen deficiency in the films, which limits the deposition rate. The film structure depends strongly on the supply ratio of oxygen molecules to titanium atoms O 2 /Ti and changes from anatase to rutile structure as the O 2 /Ti supply ratio increased. Consequently, the maximum deposition rates of 77.0 nm min -1 and 145.0 nm min -1 were obtained, respectively, for the anatase and rutile film. Both films deposited at such high rates showed excellent hydrophilicity and organic decomposition performance. Even the film with rutile structure deposited at 145.0 nm min -1 had a contact angle of less than 2.5 deg. by UV irradiation for 5.0 h and an organics-decomposition performance index of 8.9 [μmol l -1 min -1 ] for methylene blue
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Widespread functional anoxia in the oxygen minimum zone of the Eastern South Pacific
Thamdrup, Bo; Dalsgaard, Tage; Revsbech, Niels Peter
Oxygen minimum zones (OMZs) as found in the Eastern Pacific and Indian Ocean are biogeochemical hot spots with a disproportionately large role in the marine nitrogen cycle, and they are important components of the highly productive ecosystems in which they occur. Although the oxygen-depleted waters have been known for a century, oxygen levels inside them are not well constrained and the regulation of their anaerobic processes by oxygen is poorly understood. We deployed highly sensitive STOX oxygen sensors with a detection limit of 10 nmol kg-1 in combination with conventional hydrographic oxygen sensors along a cruise track transecting the Eastern South Pacific OMZ from South to North along the coast of Chile and Peru. Oxygen was below the detection limit throughout the ˜200 m thick OMZ core in most casts with STOX sensors. The only exception was an offshore location off Peru where oxygen was 10-50 nmol kg-1 in the core, likely as the result of a transient intrusion. Oxygen was also not detected in the OMZ core in further casts with conventional sensors, which had a detection limit of 90 nmol kg-1 after STOX-based zero calibration. Our measurements tighten the constraints on typical oxygen concentrations in the inner part of the OMZ by at least an order of magnitude relative to previous reports. Nitrite only accumulated when oxygen was depleted below 50 nmol kg-1, which indicates that nitrogen cycling is much more sensitive to oxygen than previously estimated. We argue that extreme oxygen depletion to low nanomalar or even picomolar concentrations is a normal condition in the South Pacific OMZ, and suggest that the OMZ core is in fact functionally anoxic over wide regions for extended periods. Our results further indicate that oxygen dynamics in the low nanomolar range play an important role in OMZ biogeochemistry.
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DEFF Research Database (Denmark)
Haase, Nicolai; Perner, Anders
2011-01-01
Shock therapy aims at increasing central venous oxygen saturation (ScvO2), which is a marker of inadequate oxygen delivery. In this issue of Critical Care, Textoris and colleagues challenge this notion by reporting that high levels of ScvO2 are associated with mortality in patients with septic sh...
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Cieszewski, Radoslaw; Linczuk, Maciej
2016-09-01
The development of FPGA technology and the increasing complexity of applications in recent decades have forced compilers to move to higher abstraction levels. Compilers interprets an algorithmic description of a desired behavior written in High-Level Languages (HLLs) and translate it to Hardware Description Languages (HDLs). This paper presents a RPython based High-Level synthesis (HLS) compiler. The compiler get the configuration parameters and map RPython program to VHDL. Then, VHDL code can be used to program FPGA chips. In comparison of other technologies usage, FPGAs have the potential to achieve far greater performance than software as a result of omitting the fetch-decode-execute operations of General Purpose Processors (GPUs), and introduce more parallel computation. This can be exploited by utilizing many resources at the same time. Creating parallel algorithms computed with FPGAs in pure HDL is difficult and time consuming. Implementation time can be greatly reduced with High-Level Synthesis compiler. This article describes design methodologies and tools, implementation and first results of created VHDL backend for RPython compiler.
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Directory of Open Access Journals (Sweden)
Long Ho
2018-02-01
Full Text Available Dissolved oxygen is an essential controlling factor in the performance of facultative and maturation ponds since both take many advantages of algal photosynthetic oxygenation. The rate of this photosynthesis strongly depends on the time during the day and the location in a pond system, whose roles have been overlooked in previous guidelines of pond operation and maintenance (O&M. To elucidate these influences, a linear mixed effect model (LMM was built on the data collected from three intensive sampling campaigns in a waste stabilization pond in Cuenca, Ecuador. Within two parallel lines of facultative and maturation ponds, nine locations were sampled at two depths in each pond. In general, the output of the mixed model indicated high spatial autocorrelations of data and wide spatiotemporal variations of the oxygen level among and within the ponds. Particularly, different ponds showed different patterns of oxygen dynamics, which were associated with many factors including flow behavior, sludge accumulation, algal distribution, influent fluctuation, and pond function. Moreover, a substantial temporal change in the oxygen level between day and night, from zero to above 20 mg O2·L−1, was observed. Algal photosynthetic activity appeared to be the main reason for these variations in the model, as it was facilitated by intensive solar radiation at high altitude. Since these diurnal and spatial patterns can supply a large amount of useful information on pond performance, insightful recommendations on dissolved oxygen (DO monitoring and regulations were delivered. More importantly, as a mixed model showed high predictive performance, i.e., high goodness-of-fit (R2 of 0.94, low values of mean absolute error, we recommended this advanced statistical technique as an effective tool for dealing with high autocorrelation of data in pond systems.
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International Nuclear Information System (INIS)
Bullen, D.B.; Gdowski, G.E.; Weiss, H.
1988-06-01
Three copper-based alloys, CDA 102 (oxygen-free copper), CDA 613 (Cu-7Al), and CDA 715 (Cu-30Ni), are being considered along with three austenitic candidates as possible materials for fabrication of containers for disposal of high-level radioactive waste. The waste will include spent fuel assemblies from reactors as well as high-level reprocessing wastes in borosilicate glass and will be sent to the prospective repository at Yucca Mountain, Nevada, for disposal. The containers must maintain mechanical integrity for 50 yr after emplacement to allow for retrieval of waste during the preclosure phase of repository operation. Containment is required to be substantially complete for up to 300 to 1000 yr. During the early period, the containers will be exposed to high temperatures and high gamma radiation fields from the decay of high-level waste. The final closure joint will be critical to the integrity of the containers. This volume surveys the available data on the metallurgy of the copper-based candidate alloys and the welding techniques employed to join these materials. The focus of this volume is on the methods applicable to remote-handling procedures in a hot-cell environment with limited possibility of postweld heat treatment. The three copper-based candidates are ranked on the basis of the various closure techniques. On the basis of considerations regarding welding, the following ranking is proposed for the copper-based alloys: CDA 715 (best) > CDA 102 > CDA 613 (worst). 49 refs., 15 figs., 1 tab
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Oxygen regulation of nitrate uptake in denitrifying Pseudomonas aeruginosa.
Hernandez, D; Rowe, J J
1987-01-01
Oxygen had an immediate and reversible inhibitory effect on nitrate respiration by denitrifying cultures of Pseudomonas aeruginosa. Inhibition of nitrate utilization by oxygen appeared to be at the level of nitrate uptake, since nitrate reduction to nitrite in cell extracts was not affected by oxygen. The degree of oxygen inhibition was dependent on the concentration of oxygen, and increasing nitrate concentrations could not overcome the inhibition. The inhibitory effect of oxygen was maximal...
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Clerbaux, T; Frans, A
1985-02-01
Clinical and pharmacological studies have shown that almitrine increased arterial blood oxygen partial pressure (PaO2) and tissular oxygenation. We have verified whether this drug could also increase the 2,3 diphosphoglycerate (DPG) level and so modify the oxyhemoglobin dissociation curve (ODC). Determinations performed 3 hours and 5 days after daily oral administration (1,5 mg/kg) of the drug showed no alterations of DPG and ODC in normal subjects. The presence of almitrine does not explain the observed PaO2 increase by means of a direct effect on the hemoglobin oxygen affinity. However, one cannot exclude almitrine long term effect; indeed, after 15 days, DPG levels and Hill coefficient increased significantly (p less than 0.05) but no the P50 (respectively + 1,5 mumole/gHb; +0.1 and 26.0 vs 26.5 mmHg).
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Langmuir, C. H.
2014-12-01
The history of oxygen and the fluxes and feedbacks that lead to its evolution through time remain poorly constrained. It is not clear whether oxygen has had discrete steady state levels at different times in Earth's history, or whether oxygen evolution is more progressive, with trigger points that lead to discrete changes in markers such as mass independent sulfur isotopes. Whatever this history may have been, ocean ridges play an important and poorly recognized part in the overall mass balance of oxidants and reductants that contribute to electron mass balance and the oxygen budget. One example is the current steady state O2 in the atmosphere. The carbon isotope data suggest that the fraction of carbon has increased in the Phanerozoic, and CO2 outgassing followed by organic matter burial should continually supply more O2 to the surface reservoirs. Why is O2 not then increasing? A traditional answer to this question would relate to variations in the fraction of burial of organic matter, but this fraction appears to have been relatively high throughout the Phanerozoic. Furthermore, subduction of carbon in the 1/5 organic/carbonate proportions would contribute further to an increasingly oxidized surface. What is needed is a flux of oxidized material out of the system. One solution would be a modern oxidized flux to the mantle. The current outgassing flux of CO2 is ~3.4*1012 moles per year. If 20% of that becomes stored organic carbon, that is a flux of .68*1012 moles per year of reduced carbon. The current flux of oxidized iron in subducting ocean crust is ~2*1012 moles per year of O2 equivalents, based on the Fe3+/Fe2+ ratios in old ocean crust compared to fresh basalts at the ridge axis. This flux more than accounts for the incremental oxidizing power produced by modern life. It also suggests a possible feedback through oxygenation of the ocean. A reduced deep ocean would inhibit oxidation of ocean crust, in which case there would be no subduction flux of oxidized
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Directory of Open Access Journals (Sweden)
Maurizio Petrozziello
2018-04-01
Full Text Available Since the end of the last century, many works have been carried out to verify the effect of controlled oxygen intake on the chemical and organoleptic characteristics of red wines. In spite of the large number of studies on this subject, oxygen remains a cutting-edge research topic in oenology. Oxygen consumption leads to complex and not univocal changes in wine composition, sometimes positive such as color stabilization, softening of mouthfeel, increase of aroma complexity. However, the variability of these effects, which depend both on the oxygenation conditions and the composition of the wine, require more efforts in this research field to effectively manage wine oxygen exposure. The present study is focused on the evolution of the chemical composition of four different Nebbiolo wines, each of them added with 4 different doses of oxygen (7, 14, 21, and 28 mg/L total intake during the first month of storage. In this perspective, the evolution over time of wine color and polyphenols was studied. Acetaldehyde, glyceraldehyde and glyoxylic acid were quantified by HPLC. These compounds can play a role in wine aging creating condensed colored and stable products involving anthocyanins with or without tannins. Moreover, some volatile aldehydes correlated with oxidized olfactory notes, including methional and (E-2-alkenals, have been quantified by GC-MS. Overall, during storage a decrease of color intensity, total and free anthocyanins and an increase in polymeric pigments (in particular the contribution to the red color of pigments not-bleachable by SO2 or dTAT% and some minor aldehydes was observed. Nevertheless, the differences in color parameters between the samples with different doses of oxygen were modest. These evidences were in contrast with an evident and detectable increase of free acetaldehyde content at increasing doses of oxygen measured after 60 days of storage. The effect of oxygen on color and production of SO2 non-bleachable pigments
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Wang, Yu; Hu, Song; Maslov, Konstantin; Zhang, Yu; Xia, Younan; Wang, Lihong V
2011-04-01
We developed dual-modality microscope integrating photoacoustic microscopy (PAM) and fluorescence confocal microscopy (FCM) to noninvasively image hemoglobin oxygen saturation (sO₂) and oxygen partial pressure (pO₂) in vivo in single blood vessels with high spatial resolution. While PAM measures sO₂ by imaging hemoglobin optical absorption at two wavelengths, FCM quantifies pO₂ using phosphorescence quenching. The variations of sO₂ and pO₂ values in multiple orders of vessel branches under hyperoxic (100% oxygen) and normoxic (21% oxygen) conditions correlate well with the oxygen-hemoglobin dissociation curve. In addition, the total concentration of hemoglobin is imaged by PAM at an isosbestic wavelength.
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Aggarwal, Neil R; Brower, Roy G; Hager, David N; Thompson, B Taylor; Netzer, Giora; Shanholtz, Carl; Lagakos, Adrian; Checkley, William
2018-04-01
High fractions of inspired oxygen may augment lung damage to exacerbate lung injury in patients with acute respiratory distress syndrome. Participants enrolled in Acute Respiratory Distress Syndrome Network trials had a goal partial pressure of oxygen in arterial blood range of 55-80 mm Hg, yet the effect of oxygen exposure above this arterial oxygen tension range on clinical outcomes is unknown. We sought to determine if oxygen exposure that resulted in a partial pressure of oxygen in arterial blood above goal (> 80 mm Hg) was associated with worse outcomes in patients with acute respiratory distress syndrome. Longitudinal analysis of data collected in these trials. Ten clinical trials conducted at Acute Respiratory Distress Syndrome Network hospitals between 1996 and 2013. Critically ill patients with acute respiratory distress syndrome. None. We defined above goal oxygen exposure as the difference between the fraction of inspired oxygen and 0.5 whenever the fraction of inspired oxygen was above 0.5 and when the partial pressure of oxygen in arterial blood was above 80 mm Hg. We then summed above goal oxygen exposures in the first five days to calculate a cumulative above goal oxygen exposure. We determined the effect of a cumulative 5-day above goal oxygen exposure on mortality prior to discharge home at 90 days. Among 2,994 participants (mean age, 51.3 yr; 54% male) with a study-entry partial pressure of oxygen in arterial blood/fraction of inspired oxygen that met acute respiratory distress syndrome criteria, average cumulative above goal oxygen exposure was 0.24 fraction of inspired oxygen-days (interquartile range, 0-0.38). Participants with above goal oxygen exposure were more likely to die (adjusted interquartile range odds ratio, 1.20; 95% CI, 1.11-1.31) and have lower ventilator-free days (adjusted interquartile range mean difference of -0.83; 95% CI, -1.18 to -0.48) and lower hospital-free days (adjusted interquartile range mean difference of -1.38; 95
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Sudhakar, Uma; Thyagarajan, Ramakrishnan; Jeyapal, Bhagyameena; Jagadeesh, Sushuruthi; Jayakumar, Parvathee
2017-01-01
Periodontal disease is not a conventional bacterial infection but is an inflammatory disease initiated by immune response against a group of microorganisms in susceptible hosts. There are many intriguing researches that unfold the secrets of chronic periodontitis. The current researches in chronic periodontitis are directed toward an approach that respects the scientific relationship between the various risk factors, the genetic factors, and the progression of the disease. This study aims to evaluate the cortisol and reactive oxygen metabolites (ROM) concentration in serum and to find out their association in periodontal health and disease. In this study, totally thirty patients have been taken and divided into two groups of chronic periodontitis (Group I) and stress-induced chronic periodontitis (Group II) and evaluated the correlation between the ROM and cortisol levels in them. This is the first study, where both the levels of ROM and cortisol are checked in the serum and saliva. The analysis is done to check the association between them. The data were statistically analyzed using software program (SPSSV 16), Pearson correlation, and paired t -test. Comparison of the mean ROM levels in Group I and Group II showed that mean ROM level in Group II is highly significant than Group I. Our study suggests that stress can have a role in the progression of periodontal disease by increasing the cortisol and ROM levels.
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1,5-Asymmetric induction in the boron-mediated aldol reaction of β-oxygenated methyl ketones
International Nuclear Information System (INIS)
Dias, Luiz C.
2007-01-01
High levels of substrate-based 1,5-stereo induction are obtained in the boron-mediated aldol reactions of β-oxygenated methyl ketones with achiral and chiral aldehydes. Remote induction from the boron enolates gives the 1,5-anti adducts, with the enolate pi-facial selectivity critically dependent upon the nature of the beta-alkoxy protecting group. This 1,5-anti aldol methodology has been strategically employed in the total synthesis of several natural products. At present, the origin of the high level of 1,5-anti induction obtained with the boron enolates is unclear, although a model based on a hydrogen bonding between the alkoxy oxygen and the formyl hydrogen has been recently proposed. (author)
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High level of oxygen treatment causes cardiotoxicity with arrhythmias and redox modulation
Energy Technology Data Exchange (ETDEWEB)
Chapalamadugu, Kalyan C.; Panguluri, Siva K. [Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, FL (United States); Bennett, Eric S. [Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL (United States); Kolliputi, Narasaiah [Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL (United States); Tipparaju, Srinivas M., E-mail: stippara@health.usf.edu [Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, FL (United States)
2015-01-01
Hyperoxia exposure in mice leads to cardiac hypertrophy and voltage-gated potassium (Kv) channel remodeling. Because redox balance of pyridine nucleotides affects Kv function and hyperoxia alters cellular redox potential, we hypothesized that hyperoxia exposure leads to cardiac ion channel disturbances and redox changes resulting in arrhythmias. In the present study, we investigated the electrical changes and redox abnormalities caused by 72 h hyperoxia treatment in mice. Cardiac repolarization changes were assessed by acquiring electrocardiogram (ECG) and cardiac action potentials (AP). Biochemical assays were employed to identify the pyridine nucleotide changes, Kv1.5 expression and myocardial injury. Hyperoxia treatment caused marked bradycardia, arrhythmia and significantly prolonged (ms) the, RR (186.2 ± 10.7 vs. 146.4 ± 6.2), PR (46.8 ± 3.1 vs. 39.3 ± 1.6), QRS (10.8 ± 0.6 vs. 8.5 ± 0.2), QTc (57.1 ± 3.5 vs. 40 ± 1.4) and JT (13.4 ± 2.1 vs. 7.0 ± 0.5) intervals, when compared with normoxia group. Hyperoxia treatment also induced significant increase in cardiac action potential duration (APD) (ex-APD{sub 90}; 73.8 ± 9.5 vs. 50.9 ± 3.1 ms) and elevated levels of serum markers of myocardial injury; cardiac troponin I (TnI) and lactate dehydrogenase (LDH). Hyperoxia exposure altered cardiac levels of mRNA/protein expression of; Kv1.5, Kvβ subunits and SiRT1, and increased ratios of reduced pyridine nucleotides (NADH/NAD and NADPH/NADP). Inhibition of SiRT1 in H9C2 cells using Splitomicin resulted in decreased SiRT1 and Kv1.5 expression, suggesting that SiRT1 may mediate Kv1.5 downregulation. In conclusion, the cardiotoxic effects of hyperoxia exposure involve ion channel disturbances and redox changes resulting in arrhythmias. - Highlights: • Hyperoxia treatment leads to arrhythmia with prolonged QTc and action potential duration. • Hyperoxia treatment alters cardiac pyridine nucleotide [NAD(P)H/NAD(P)] levels. • SiRT1 and Kv1.5 are co
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High level of oxygen treatment causes cardiotoxicity with arrhythmias and redox modulation
International Nuclear Information System (INIS)
Chapalamadugu, Kalyan C.; Panguluri, Siva K.; Bennett, Eric S.; Kolliputi, Narasaiah; Tipparaju, Srinivas M.
2015-01-01
Hyperoxia exposure in mice leads to cardiac hypertrophy and voltage-gated potassium (Kv) channel remodeling. Because redox balance of pyridine nucleotides affects Kv function and hyperoxia alters cellular redox potential, we hypothesized that hyperoxia exposure leads to cardiac ion channel disturbances and redox changes resulting in arrhythmias. In the present study, we investigated the electrical changes and redox abnormalities caused by 72 h hyperoxia treatment in mice. Cardiac repolarization changes were assessed by acquiring electrocardiogram (ECG) and cardiac action potentials (AP). Biochemical assays were employed to identify the pyridine nucleotide changes, Kv1.5 expression and myocardial injury. Hyperoxia treatment caused marked bradycardia, arrhythmia and significantly prolonged (ms) the, RR (186.2 ± 10.7 vs. 146.4 ± 6.2), PR (46.8 ± 3.1 vs. 39.3 ± 1.6), QRS (10.8 ± 0.6 vs. 8.5 ± 0.2), QTc (57.1 ± 3.5 vs. 40 ± 1.4) and JT (13.4 ± 2.1 vs. 7.0 ± 0.5) intervals, when compared with normoxia group. Hyperoxia treatment also induced significant increase in cardiac action potential duration (APD) (ex-APD 90 ; 73.8 ± 9.5 vs. 50.9 ± 3.1 ms) and elevated levels of serum markers of myocardial injury; cardiac troponin I (TnI) and lactate dehydrogenase (LDH). Hyperoxia exposure altered cardiac levels of mRNA/protein expression of; Kv1.5, Kvβ subunits and SiRT1, and increased ratios of reduced pyridine nucleotides (NADH/NAD and NADPH/NADP). Inhibition of SiRT1 in H9C2 cells using Splitomicin resulted in decreased SiRT1 and Kv1.5 expression, suggesting that SiRT1 may mediate Kv1.5 downregulation. In conclusion, the cardiotoxic effects of hyperoxia exposure involve ion channel disturbances and redox changes resulting in arrhythmias. - Highlights: • Hyperoxia treatment leads to arrhythmia with prolonged QTc and action potential duration. • Hyperoxia treatment alters cardiac pyridine nucleotide [NAD(P)H/NAD(P)] levels. • SiRT1 and Kv1.5 are co-regulated in
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Internal-reference solid-electrolyte oxygen sensor
International Nuclear Information System (INIS)
Haaland, D.M.
1977-01-01
A new solid-electrolyte oxygen sensor has been developed that eliminates the conventional oxygen reference in previous solid-electrolyte oxygen sensor designs and is, therefore, ideally suited as an insertion device for remote oxygen monitoring applications. It is constructed with two cells of stabilized zirconia sealed into a small unit using a new high-temperature platinum-zirconia seal. One electrochemical cell monitors the ratio of oxygen partial pressures inside and outside the sensor while the other solid-electrolyte cell is used for quantitative electrochemical pumping of oxygen. The internal oxygen reference is generated by initially pumping all oxygen out of the known internal volume of the sensor and then quantitatively pumping oxygen back in until oxygen partial pressures are equal inside and out. This information is used with the ideal gas law to calculate oxygen partial pressures. Tests were conducted from 400 to 1000 0 C in mixtures of oxygen and nitrogen spanning approximately 0.2 to 21 percent oxygen concentration range. Sensors with sputtered platinum and porous platinum paste electrodes were compared
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Modelling of zircaloy-4 degradation in oxygen and nitrogen mixtures at high temperature
International Nuclear Information System (INIS)
Lasserre-Gagnaire, Marina
2013-01-01
Zircaloy-4 claddings provide the first containment of UO 2 fuel in Pressurised Water Reactors. It has been demonstrated that the fuel assemblies cladding could be exposed to air at high temperature in several accidental situations such as a loss of cooling accident in a spent fuel storage When mixed to oxygen at high temperature, the nitrogen, usually used as an inert gas, causes the accelerated corrosion of the cladding. The kinetic curves obtained by thermogravimetry reveal two stages: a pre-transition and a post-transition one. The pre-transition stage corresponds to the growth of a protective dense oxide layer: the kinetic rate decreases with time and is controlled by oxygen vacancy diffusion in the oxide layer. In the post-transition stage, the oxide layer is no longer protective and the kinetic rate increases with time. Images obtained by optical microscopy of a sample in the post-transition stage reveal the presence of corroded zones characterized by a porous scale with zirconium nitride precipitates at metal - oxide interface. Corrosion of Zy4 plates at 850 deg. C under mixed oxygen - nitrogen atmospheres has been studied during the post-transition stage. A sequence of three reactions is proposed to explain the mechanism of nitrogen-enhanced corrosion and the porosity of the corroded regions. The accelerating effect of nitrogen in the corrosion scale can therefore be described on the basis of an autocatalytic effect of the zirconium nitride precipitates. Then, it is demonstrated that the steady-state approximation as well as the existence of an elementary step controlling the growth process are valid during the post-transition stage. Thanks to the study of the variations of the surface rate of growth with the oxygen and nitrogen partial pressure, the rate-determining step is identified as the external interface reaction step of the oxidation of the zirconium nitride precipitates. Finally, a nucleation and growth model used for thermal reactions in powders
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Oxygen - A Four Billion Year History
DEFF Research Database (Denmark)
Canfield, Donald Eugene
The air we breathe is twenty-one percent oxygen, an amount higher than on any other known world. While we may take our air for granted, Earth was not always an oxygenated planet. How did it become this way? Oxygen is the most current account of the history of atmospheric oxygen on Earth. Donald...... Canfield--one of the world's leading authorities on geochemistry, earth history, and the early oceans--covers this vast history, emphasizing its relationship to the evolution of life and the evolving chemistry of the Earth. With an accessible and colorful first-person narrative, he draws from a variety...... of fields, including geology, paleontology, geochemistry, biochemistry, animal physiology, and microbiology, to explain why our oxygenated Earth became the ideal place for life. Describing which processes, both biological and geological, act to control oxygen levels in the atmosphere, Canfield traces...
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Intraoperative transfusion threshold and tissue oxygenation
DEFF Research Database (Denmark)
Nielsen, K; Dahl, B; Johansson, P I
2012-01-01
Transfusion with allogeneic red blood cells (RBCs) may be needed to maintain oxygen delivery during major surgery, but the appropriate haemoglobin (Hb) concentration threshold has not been well established. We hypothesised that a higher level of Hb would be associated with improved subcutaneous...... oxygen tension during major spinal surgery....
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Energy Technology Data Exchange (ETDEWEB)
Liu, Bin; Yan, Pengfei; Xu, Wu; Zheng, Jianming; He, Yang; Luo, Langli; Bowden, Mark E.; Wang, Chong-Min; Zhang, Ji-Guang
2016-08-10
Lithium-oxygen (Li-O2) battery has an extremely high theoretical specific energy density as compared with conventional energy storage systems. However, practical application of Li-O2 battery system still faces significant challenges, especially its poor cyclability. In this work, we report a new approach to synthesis ultrafine metal oxide nanocatalysts through an electrochemical pre-lithiation process. This process reduces the size of NiCo2O4 (NCO) particles from 20~30 nm to a uniformly distributed domain of ~ 2 nm and largely improved their catalytic activity. Structurally, the pre-lithiated NCO NWs are featured by ultrafine NiO/CoO nanoparticles, which show high stability during prolonged cycles in terms of morphology and the particle size, therefore maintaining an excellent catalytic effect to oxygen reduction and evolution reactions. Li-O2 battery using this catalyst has demonstrated an initial capacity of 29,280 mAh g-1 and has retained a stable capacity of over 1,000 mAh g-1 after 100 cycles based on the weight of NCO active material. Direct in-situ TEM observation conclusively reveals the lithiation/delithiation process of as-prepared NCO NWs, clarifying the NCO/Li electrochemical reaction mechanism that can be extended to other transition-metal oxides and providing the in depth understandings on the catalysts and battery chemistries of other ternary transition-metal oxides.
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Takayanagi, Masayoshi; Kurisaki, Ikuo; Nagaoka, Masataka
2014-04-08
Protein allostery is essential for vital activities. Allosteric regulation of human hemoglobin (HbA) with two quaternary states T and R has been a paradigm of allosteric structural regulation of proteins. It is widely accepted that oxygen molecules (O2) act as a "site-specific" homotropic effector, or the successive O2 binding to the heme brings about the quaternary regulation. However, here we show that the site-specific allosteric effect is not necessarily only a unique mechanism of O2 allostery. Our simulation results revealed that the solution environment of high O2 partial pressure enhances the quaternary change from T to R without binding to the heme, suggesting an additional "non-site-specific" allosteric effect of O2. The latter effect should play a complementary role in the quaternary change by affecting the intersubunit contacts. This analysis must become a milestone in comprehensive understanding of the allosteric regulation of HbA from the molecular point of view.
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Directory of Open Access Journals (Sweden)
M Tanweer Khan
Full Text Available The beneficial human gut microbe Faecalibacterium prausnitzii is a 'probiotic of the future' since it produces high amounts of butyrate and anti-inflammatory compounds. However, this bacterium is highly oxygen-senstive, making it notoriously difficult to cultivate and preserve. This has so far precluded its clinical application in the treatment of patients with inflammatory bowel diseases. The present studies were therefore aimed at developing a strategy to keep F. prausnitzii alive at ambient air. Our previous research showed that F. prausnitzii can survive in moderately oxygenized environments like the gut mucosa by transfer of electrons to oxygen. For this purpose, the bacterium exploits extracellular antioxidants, such as riboflavin and cysteine, that are abundantly present in the gut. We therefore tested to what extent these antioxidants can sustain the viability of F. prausnitzii at ambient air. The present results show that cysteine can facilitate the survival of F. prausnitzii upon exposure to air, and that this effect is significantly enhanced the by addition of riboflavin and the cryoprotectant inulin. The highly oxygen-sensitive gut bacterium F. prausnitzii can be kept alive at ambient air for 24 h when formulated with the antioxidants cysteine and riboflavin plus the cryoprotectant inulin. Improved formulations were obtained by addition of the bulking agents corn starch and wheat bran. Our present findings pave the way towards the biomedical exploitation of F. prausnitzii in redox-based therapeutics for treatment of dysbiosis-related inflammatory disorders of the human gut.
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International Nuclear Information System (INIS)
Chen Yu; Tailor, Dharmesh R; Intes, Xavier; Chance, Britton
2003-01-01
We measure the tissue oxygen and haemoglobin concentrations in the rat brain during modulation of inhaled oxygen concentration (FiO 2 ), using non-invasive frequency domain near-infrared oximetry. The rise in oxygenated haemoglobin concentration and the decline in deoxygenated haemoglobin concentration are demonstrated in correspondence with the modulation of FiO 2 , which is changed from 20% to 100% in increments of 20%. Furthermore, the tissue oxygenation saturation also shows the corresponding trend and changes ranging from approximately 70% to 90%. The relative changes in deoxygenated haemoglobin concentration are compared to the blood-oxygenation-level-dependent (BOLD) MRI signal recorded during a similar FiO 2 protocol. A linear relationship with high correlation coefficient between the relative changes in the BOLD MRI signal and the NIRS signal is observed
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Energy Technology Data Exchange (ETDEWEB)
Chen Yu [Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA (United States); Tailor, Dharmesh R [Department of Bioengineering, University of Pennsylvania, Philadelphia, PA (United States); Intes, Xavier [Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA (United States); Chance, Britton [Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA (United States)
2003-02-21
We measure the tissue oxygen and haemoglobin concentrations in the rat brain during modulation of inhaled oxygen concentration (FiO{sub 2}), using non-invasive frequency domain near-infrared oximetry. The rise in oxygenated haemoglobin concentration and the decline in deoxygenated haemoglobin concentration are demonstrated in correspondence with the modulation of FiO{sub 2}, which is changed from 20% to 100% in increments of 20%. Furthermore, the tissue oxygenation saturation also shows the corresponding trend and changes ranging from approximately 70% to 90%. The relative changes in deoxygenated haemoglobin concentration are compared to the blood-oxygenation-level-dependent (BOLD) MRI signal recorded during a similar FiO{sub 2} protocol. A linear relationship with high correlation coefficient between the relative changes in the BOLD MRI signal and the NIRS signal is observed.
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Díaz-Lobato, Salvador; Folgado, Miguel Angel; Chapa, Angel; Mayoralas Alises, Sagrario
2013-12-01
The treatment of choice for patients with respiratory failure of neuromuscular origin, especially in patients with hypercapnic respiratory acidosis, is noninvasive ventilation (NIV). Endotracheal intubation and invasive ventilation are indicated for patients with severe respiratory compromise or failure of NIV. In recent years, high-flow oxygen therapy and active humidification devices have been introduced, and emerging evidence suggests that high-flow oxygen may be effective in various clinical settings, such as acute respiratory failure, after cardiac surgery, during sedation and analgesia, in acute heart failure, in hypoxemic respiratory distress, in do-not-intubate patients, in patients with chronic cough and copious secretions, pulmonary fibrosis, or cancer, in critical areas and the emergency department. We report on a patient with amyotrophic lateral sclerosis who arrived at the emergency department with acute hypercapnic respiratory failure. She did not tolerate NIV and refused intubation, but was treated successfully with heated, humidified oxygen via high-flow nasal cannula. Arterial blood analysis after an hour on high-flow nasal cannula showed improved pH, P(aCO2), and awareness. The respiratory acidosis was corrected, and she was discharged after 5 days of hospitalization. Her response to high-flow nasal cannula was similar to that expected with NIV. We discuss the mechanisms of action of heated, humidified high-flow oxygen therapy.
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Wine evolution and spatial distribution of oxygen during storage in high-density polyethylene tanks.
del Alamo-Sanza, María; Laurie, V Felipe; Nevares, Ignacio
2015-04-01
Porous plastic tanks are permeable to oxygen due to the nature of the polymers with which they are manufactured. In the wine industry, these types of tanks are used mainly for storing wine surpluses. Lately, their use in combination with oak pieces has also been proposed as an alternative to mimic traditional barrel ageing. In this study, the spatial distribution of dissolved oxygen in a wine-like model solution, and the oxygen transfer rate (OTR) of high-density polyethylene tanks (HDPE), was analysed by means of a non-invasive opto-luminescence detector. Also, the chemical and sensory evolution of red wine, treated with oak pieces, and stored in HDPE tanks was examined and compared against traditional oak barrel ageing. The average OTR calculated for these tanks was within the commonly accepted amounts reported for new barrels. With regards to wine evolution, a number of compositional and sensory differences were observed between the wines aged in oak barrels and those stored in HDPE tanks with oak barrel alternatives. The use of HDPE tanks in combination with oak wood alternatives is a viable alternative too for ageing wine. © 2014 Society of Chemical Industry.
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Lankhorst, M.H.R.; Lankhorst, M.H.R.; Bouwmeester, Henricus J.M.
1997-01-01
The oxygen nonstoichiometry of La0.8Sr0.2CoO3-delta has been determined as a function of oxygen partial pressure and temperature using a high-temperature coulometric titration cell. For each measured value of the oxygen chemical potential, the oxygen nonstoichiometry is found to be nearly
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Tidrow, Steven Clay
Two primary concerns, in the sputter deposition of high T_{c} material films, are the prevention of oxygen deficiency in the films and the elimination of the negative ion effect. "Oxygen deficiency" occurs when the amount of oxygen incorporated into the film is less than the amount of oxygen required to form the superconducting material lattice. Oxygen deficiency is due to the volatile nature of oxygen. The negative ion effect occurs when an atom or molecule (typically oxygen) gains an extra electron, is accelerated away from the target and impinges upon a film being grown directly in front of the sputtering target. The impinging particle has enough energy to cause resputtering of the deposited film. The presence of Sr and to a greater extent Ba, may enhance the negative ion effect in these materials. However, it is oxygen which readily forms negative ions that is primarily responsible for the negative ion effect. Thus, oxygen must be given special attention in the sputter deposition of high T_{c} material films. A specially designed sputtering system is used to demonstrate that the negative ion effect can be reduced such that large uniform high T_{c} material films possessing predicted and repeated composition can be grown in an on-axis arrangement. Utilizing this same sputtering system and the volatile nature of oxygen, it is demonstrated that oxygen processes occurring in the chamber during growth of high T_ {c} material films can be investigated using the tracer ^{18}O. In particular, it is shown that ^{18}O can be utilized as a tool for (1) investigating the negative ion effect, (2) investigating oxygen incorporation into high T_{c} material films, (3) investigating oxygen incorporation into the target, (4) tailoring films for oxygen migration and interface investigations and (5) tailoring films for the other specific oxygen investigations. Such sputtering systems that utilize the tracer ^{18}O are necessary for systematic growth of high T_ {c} material films
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Kinetics of highly vibrationally excited O2(X) molecules in inductively-coupled oxygen plasmas
Annušová, Adriana; Marinov, Daniil; Booth, Jean-Paul; Sirse, Nishant; Lino da Silva, Mário; Lopez, Bruno; Guerra, Vasco
2018-04-01
The high degree of vibrational excitation of O2 ground state molecules recently observed in inductively coupled plasma discharges is investigated experimentally in more detail and interpreted using a detailed self-consistent 0D global kinetic model for oxygen plasmas. Additional experimental results are presented and used to validate the model. The vibrational kinetics considers vibrational levels up to v = 41 and accounts for electron impact excitation and de-excitation (e-V), vibration-to-translation relaxation (V-T) in collisions with O2 molecules and O atoms, vibration-to-vibration energy exchanges (V-V), excitation of electronically excited states, dissociative electron attachment, and electron impact dissociation. Measurements were performed at pressures of 10–80 mTorr (1.33 and 10.67 Pa) and radio frequency (13.56 MHz) powers up to 500 W. The simulation results are compared with the absolute densities in each O2 vibrational level obtained by high sensitivity absorption spectroscopy measurements of the Schumann–Runge bands for O2(X, v = 4–18), O(3 P) atom density measurements by two-photon absorption laser induced fluorescence (TALIF) calibrated against Xe, and laser photodetachment measurements of the O‑ negative ions. The highly excited O2(X, v) distribution exhibits a shape similar to a Treanor-Gordiets distribution, but its origin lies in electron impact e-V collisions and not in V-V up-pumping, in contrast to what happens in all other molecular gases known to date. The relaxation of vibrational quanta is mainly due to V-T energy-transfer collisions with O atoms and to electron impact dissociation of vibrationally excited molecules, e+O2(X, v)→O(3P)+O(3P).
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Direct imaging of fractional oxygen Oδ in Hg-based high-Tc superconductors
International Nuclear Information System (INIS)
Papoular, R.J.; Collin, G.; Colson, D.; Viallet, V.
2002-01-01
Maximum Entropy is applied to the crystallographic imaging of x-ray diffraction data in order to reveal reliable model-free weak electron density features (if any) in newly discovered high-T c superconductors. The use of suitably computed non-uniform priors turns out to be essential. The suggested maxentropic procedure shows that about .2 oxygen atoms [1.6 electrons] can unambiguously be evidenced near the much heavier mercury atoms [harboring 80 electrons each], and this from standard laboratory [non-synchrotron] x-ray data
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The antioxidant level of Alaska's wild berries: high, higher and highest
Directory of Open Access Journals (Sweden)
Roxie Rodgers Dinstel
2013-08-01
Full Text Available Background . In the last few years, antioxidants have become the stars of the nutritional world. Antioxidants are important in terms of their ability to protect against oxidative cell damage that can lead to conditions, such as Alzheimer's disease, cancer and heart disease – conditions also linked with chronic inflammation. The antioxidant and anti-inflammatory effects of Alaska's wild berries may have the potential to help prevent these diseases. Objective . To discover the antioxidant levels of Alaska wild berries and the ways these antioxidant levels translate when preservation methods are applied to the berry. Design . This research centred on both the raw berries and products made from the berries. In the first year, a variety of wild berries were tested to discover their oxygen radical absorption capacity (ORAC in the raw berries. The second level of the research project processed 4 different berries – blueberries, lingonberries, salmonberries, highbush cranberries – into 8 or 9 products made from these berries. The products were tested for both ORAC as well as specific antioxidants. Results . The Alaska wild berries collected and tested in the first experiment ranged from 3 to 5 times higher in ORAC value than cultivated berries from the lower 48 states. For instance, cultivated blueberries have an ORAC scale of 30. Alaska wild dwarf blueberries measure 85. This is also higher than lower 48 wild blueberries, which had a score of 61. All of the Alaskan berries tested have a level of antioxidant considered nutritionally valuable, ranging from 19 for watermelon berries to 206 for lingonberries on the ORAC scale. With the processed products made from 4 Alaska wild berries, one of the unexpected outcomes of the research was that the berries continued to have levels of antioxidants considered high, despite the effects of commonly used heat-processing techniques. When berries were dehydrated, per gram ORAC values increased. Conclusion
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The Synergetic Effects of Hydrogen and Oxygen on the Strength and Ductility of Vanadium Alloys
Institute of Scientific and Technical Information of China (English)
Chen Jiming(谌继明); Xu Ying(徐颖); Deng Ying(邓颖); Yang Ling(杨霖); Qiu Shaoyu(邱绍宇)
2003-01-01
A V4Ti alloy and several V4Cr4Ti alloys with different oxygen contents were studied on their tensile properties with the effect of hydrogen concentrations. The ductility of the alloys showed a successive decrease in a varied rate with an increased hydrogen concentration, while the ultimate tensile strength remained unchanged or even decreased for the high oxygen content alloy in spite of the occurrence of hardening in the low oxygen content alloy. Oxygen in the alloy causes grain boundary weakening, increasing the possibility of intergranular fractures and thus enhancing the hydrogen embrittlement. V4Ti showed a higher resistance to the hydrogen embrittlement as compared to the V4Cr4Ti alloys on a similar oxygen content level.
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Optimal oxygen saturation in premature infants
Directory of Open Access Journals (Sweden)
Meayoung Chang
2011-09-01
Full Text Available There is a delicate balance between too little and too much supplemental oxygen exposure in premature infants. Since underuse and overuse of supplemental oxygen can harm premature infants, oxygen saturation levels must be monitored and kept at less than 95% to prevent reactive oxygen species-related diseases, such as retinopathy of prematurity and bronchopulmonary dysplasia. At the same time, desaturation below 80 to 85% must be avoided to prevent adverse consequences, such as cerebral palsy. It is still unclear what range of oxygen saturation is appropriate for premature infants; however, until the results of further studies are available, a reasonable target for pulse oxygen saturation (SpO2 is 90 to 93% with an intermittent review of the correlation between SpO2 and the partial pressure of arterial oxygen tension (PaO2. Because optimal oxygenation depends on individuals at the bedside making ongoing adjustments, each unit must define an optimal target range and set alarm limits according to their own equipment or conditions. All staff must be aware of these values and adjust the concentration of supplemental oxygen frequently.
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Herald, Stephen D.; Frisby, Paul M.; Davis, Samuel Eddie
2009-01-01
Safe and reliable seal materials for high-pressure oxygen systems sometimes appear to be extinct species when sought out by oxygen systems designers. Materials that seal well are easy to find, but these materials are typically incompatible with oxygen, especially in cryogenic liquid form. This incompatibility can result in seals that leak, or much worse, seals that easily ignite and burn during use. Materials that are compatible with oxygen are easy to find, such as the long list of compatible metals, but these metallic materials are limiting as seal materials. A material that seals well and is oxygen compatible has been the big game in the designer's safari. Scientists at the Materials Combustion Research Facility (MCRF), part of NASA/Marshall Space Flight Center (MSFC), are constantly searching for better materials and processes to improve the safety of oxygen systems. One focus of this effort is improving the characteristics of polymers used in the presence of an oxygen enriched environment. Very few systems can be built which contain no polymeric materials; therefore, materials which have good impact resistance, low heat of combustion, high auto-ignition temperature and that maintain good mechanical properties are essential. The scientists and engineers at the Materials Combustion Research Facility, in cooperation with seal suppliers, are currently testing a new formulation of polytetrafluoroethylene (PTFE) with Brass filler. This Brass-filled PTFE is showing great promise as a seal and seat material for high pressure oxygen systems. Early research has demonstrated very encouraging results, which could rank this material as one of the best fluorinated polymers ever tested. This paper will compare the data obtained for Brass-filled PTFE with other fluorinated polymers, such as TFE-Teflon (PTFE) , Kel-F 81, Viton A, Viton A-500, Fluorel , and Algoflon . A similar metal filled fluorinated polymer, Salox-M , was tested in comparison to Brass-filled PTFE to
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Cui, Xingkai; Yang, Xiaofei; Xian, Xiaozhai; Tian, Lin; Tang, Hua; Liu, Qinqin
2018-04-01
Oxygen evolution has been considered as the rate-determining step in photocatalytic water splitting due to its sluggish four-electron half-reaction rate, the development of oxygen-evolving photocatalysts with well-defined morphologies and superior interfacial contact is highly important for achieving high-performance solar water splitting. Herein, we report the fabrication of Ag3PO4/MoS2 nanocomposites and, for the first time, their use in photocatalytic water splitting into oxygen under LED light illumination. Ag3PO4 nanoparticles were found to be anchored evenly on the surface of MoS2 nanosheets, confirming an efficient hybridization of two semiconductor materials. A maximum oxygen-generating rate of 201.6 mol L-1 g-1 h-1 was determined when 200 mg MoS2 nanosheets were incorporated into Ag3PO4 nanoparticles, which is around 5 times higher than that of bulk Ag3PO4. Obvious enhancements in light-harvesting property, as well as electron-hole separation and charge transportation are revealed by the combination of different characterizations. ESR analysis verified that more active oxygen-containing radicals generate over illuminated Ag3PO4/MoS2 composite photocatalysts rather than irradiated Ag3PO4. The improvement in oxygen evolution performance of Ag3PO4/MoS2 composite photocatalysts is ascribed to wide spectra response in the visible-light region, more efficient charge separation and enhanced oxidation capacity in the valence band (VB). This study provides new insights into the design and development of novel composite photocatalytic materials for solar-to-fuel conversion.
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CHROMOSPHERIC MODELS AND THE OXYGEN ABUNDANCE IN GIANT STARS
Energy Technology Data Exchange (ETDEWEB)
Dupree, A. K.; Avrett, E. H.; Kurucz, R. L., E-mail: dupree@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
2016-04-10
Realistic stellar atmospheric models of two typical metal-poor giant stars in Omega Centauri, which include a chromosphere (CHR), influence the formation of optical lines of O i: the forbidden lines (λ6300, λ6363) and the infrared triplet (λλ7771−7775). One-dimensional semi-empirical non-local thermodynamic equilibrium (LTE) models are constructed based on observed Balmer lines. A full non-LTE formulation is applied for evaluating the line strengths of O i, including photoionization by the Lyman continuum and photoexcitation by Lyα and Lyβ. Chromospheric models (CHR) yield forbidden oxygen transitions that are stronger than those in radiative/convective equilibrium (RCE) models. The triplet oxygen lines from high levels also appear stronger than those produced in an RCE model. The inferred oxygen abundance from realistic CHR models for these two stars is decreased by factors of ∼3 as compared to values derived from RCE models. A lower oxygen abundance suggests that intermediate-mass AGB stars contribute to the observed abundance pattern in globular clusters. A change in the oxygen abundance of metal-poor field giants could affect models of deep mixing episodes on the red giant branch. Changes in the oxygen abundance can impact other abundance determinations that are critical to astrophysics, including chemical tagging techniques and galactic chemical evolution.
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Conductor of high electrical current at high temperature in oxygen and liquid metal environment
Powell, IV, Adam Clayton; Pati, Soobhankar; Derezinski, Stephen Joseph; Lau, Garrett; Pal, Uday B.; Guan, Xiaofei; Gopalan, Srikanth
2016-01-12
In one aspect, the present invention is directed to apparatuses for and methods of conducting electrical current in an oxygen and liquid metal environment. In another aspect, the invention relates to methods for production of metals from their oxides comprising providing a cathode in electrical contact with a molten electrolyte, providing a liquid metal anode separated from the cathode and the molten electrolyte by a solid oxygen ion conducting membrane, providing a current collector at the anode, and establishing a potential between the cathode and the anode.
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Oxygen Tension in the Aqueous Humor of Human Eyes under Different Oxygenation Conditions
Directory of Open Access Journals (Sweden)
Farideh Sharifipour
2013-01-01
Full Text Available Purpose: To measure oxygen tension in the aqueous humor of human eyes under different oxygenation conditions. Methods: This prospective comparative interventional case series consisted of two parts. In the first part, 120 consecutive patients scheduled for cataract surgery were randomized into group I (control group in which surgery was performed under local anesthesia inhaling 21% oxygen; group II in whom general anesthesia using 50% oxygen was employed; and group III receiving general anesthesia with 100% oxygen. After aspirating 0.2 ml aqueous humor under sterile conditions, the aqueous sample and a simultaneously drawn arterial blood sample were immediately analyzed using a blood gas analyzer. In part II the same procedures were performed in 10 patients after fitting a contact lens and patching the eye for 20 minutes (group IV and in 10 patients after transcorneal delivery of oxygen at a flow rate of 5 L/min (group V. Results: Mean aqueous PO2 in groups I, II and III was 112.3±6.2, 141.1±20.4, and 170.1±27 mmHg, respectively (P values <0.001 and mean arterial PO2 was 85.7±7.9, 184.6±46, and 379.1±75.9 mmHg, respectively (P values <0.001. Aqueous PO2 was 77.2±9.2 mmHg in group IV and 152.3±10.9 mmHg in group V (P values <0.001. There was a significant correlation between aqueous and blood PO2 (r=0.537, P<0.001. The contribution of atmospheric oxygen to aqueous PO2 was 23.7%. Conclusion: Aqueous oxygen tension is mostly dependent on the systemic circulation and in part on the atmosphere. Increasing inspiratory oxygen and transcorneal oxygen delivery both increase aqueous PO2 levels.
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Electron attachment to molecules and clusters of atmospheric relevance: oxygen and ozone
International Nuclear Information System (INIS)
Matejcik, S.; Cicman, P.; Skalny, J.; Kiendler, A.; Stampfli, P.; Maerk, T.D.; Illenberger, E.; Chu, Y.; Stamatovic, A.
1996-01-01
Highly monochromatized electrons are used in a crossed beams experiment to investigate electron attachment to oxygen clusters (O 2 )-n at electron energies from approximately zero eV up to 2 eV. At energies close to zero the attachment cross section for the reaction (O 2 ) n + e → O 2 - varies inversely with the electron energy, indicative of s-wave electron capture to (O 2 ) n . Peaks in the attachment cross section present at higher energies can be ascribed to vibrational levels of the oxygen anion. The vibrational spacings observed can be quantitatively accounted for. In addition electron attachment to ozone and mixed oxygen/ozone clusters has been studied in the energy range up to 4 eV. Absolute attachment cross sections for both fragment ions anions, O - and O 2 - , from ozone could be deduced. Moreover, despite the initially large excess of oxygen molecules in the neutral oxygen/ozone clusters the dominant attachment products are un-dissociated cluster ions (O 3 ) m - including the O 3 - monomer while oxygen cluster ions (O 2 ) n appear with comparatively low intensity. (authors)
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International Nuclear Information System (INIS)
Gauquelin, Nicolas
2010-01-01
La 2 NiO 4+δ was first studied due to its structural similarities with the High Temperature superconductor La 2 NiO 4+δ and more recently due to its promise as a cathode material in Solid Oxide Fuel Cells as well as an oxygen exchange membrane. It crystallizes in the K 2 NiF 4 layered structure and accommodates highly mobile oxygen at its ground state and is therefore overstoichiometric. During this thesis, pure single crystals of La 2 NiO 4+δ were successfully grown using the floating-zone method, subsequently characterized using neutron and Laue Backscattering diffraction and oriented pieces of single crystal with [100] and [001] orientation were prepared. The surface morphology behavior after long term exposure to high temperature in different atmospheres was observed using microscopy techniques because stability at high temperature is required for application purposes and it was discovered a structural change to nickel-rich phases at T>1173 K. The sensibility of the oxygen non-stoichiometry to cooling was studied and subsequently a new 18 O- 18 O exchange apparatus allowing quenching of the samples using liquid nitrogen was developed. Oxygen selfdiffusion was studied using SIMS in the range 673-873K in both [100] and [001] crystallographic directions. The effect of the disorientation of the sample surface on the determination of the slowest diffusion coefficient was discovered and revealed the very strong anisotropy (>5 orders of magnitude difference) between the different diffusion paths. Finally using HTXRD and oxygen release experiments, it was shown that oxygen diffusion from interstitial oxygen starts to be relevant at 550-600 K and a change of behavior is observed around 700 K, corresponding to a possible change in the diffusion mechanism from interstitial to interstitialcy.
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... level is very high, or if you have danger signs, such as changes in an ECG . Emergency ... Seifter JL. Potassium disorders. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine . 25th ed. Philadelphia, PA: ...
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Girard, Olivier; Brocherie, Franck; Morin, Jean-Benoit; Millet, Grégoire P
2017-01-01
To examine mechanical alterations during interval-training treadmill runs in high-level team-sport players. Within-participants repeated measures. Twenty high-level male field-hockey players performed six 30-s runs at 5.53±0.19ms -1 corresponding to 115% of their velocity associated with maximal oxygen uptake (vVO 2max ) with 30-s passive recovery on an instrumented treadmill. Continuous measurement of running kinetics/kinematics and spring-mass characteristics were performed and values were subsequently averaged over 20s (8th-28ths) for comparison. Contact time (+1.1±4.3%; p=0.044), aerial time (+4.1±5.3%; p=0.001), step length (+2.4±2.2%; pteam-sport players modified their mechanical behaviour towards lower vertical stiffness while preserving a constant leg stiffness. Maintenance of running velocity induced longer step lengths and decreased step frequencies that were also accompanied by increased impact loading rates. These mechanical alterations occurred early during the set. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
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Strategies toward High-Performance Cathode Materials for Lithium-Oxygen Batteries.
Wang, Kai-Xue; Zhu, Qian-Cheng; Chen, Jie-Sheng
2018-05-11
Rechargeable aprotic lithium (Li)-O 2 batteries with high theoretical energy densities are regarded as promising next-generation energy storage devices and have attracted considerable interest recently. However, these batteries still suffer from many critical issues, such as low capacity, poor cycle life, and low round-trip efficiency, rendering the practical application of these batteries rather sluggish. Cathode catalysts with high oxygen reduction reaction (ORR) and evolution reaction activities are of particular importance for addressing these issues and consequently promoting the application of Li-O 2 batteries. Thus, the rational design and preparation of the catalysts with high ORR activity, good electronic conductivity, and decent chemical/electrochemical stability are still challenging. In this Review, the strategies are outlined including the rational selection of catalytic species, the introduction of a 3D porous structure, the formation of functional composites, and the heteroatom doping which succeeded in the design of high-performance cathode catalysts for stable Li-O 2 batteries. Perspectives on enhancing the overall electrochemical performance of Li-O 2 batteries based on the optimization of the properties and reliability of each part of the battery are also made. This Review sheds some new light on the design of highly active cathode catalysts and the development of high-performance lithium-O 2 batteries. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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DEFF Research Database (Denmark)
various journals and collections. As a result, much of this knowledge is not readily available to people who may be interested in using high-level nets. Within the Petri net community this problem has been discussed many times, and as an outcome this book has been compiled. The book contains reprints...... of some of the most important papers on the application and theory of high-level Petri nets. In this way it makes the relevant literature more available. It is our hope that the book will be a useful source of information and that, e.g., it can be used in the organization of Petri net courses. To make......High-level Petri nets are now widely used in both theoretical analysis and practical modelling of concurrent systems. The main reason for the success of this class of net models is that they make it possible to obtain much more succinct and manageable descriptions than can be obtained by means...
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DEFF Research Database (Denmark)
Rosenberg, J; Pedersen, U; Erichsen, C J
1994-01-01
The effect of oxygen therapy (37% by face mask) and epidural local anesthetic blockade (9 ml 0.5% bupivacaine at Th9-11 level) on wound oxygenation was evaluated in eight otherwise healthy patients undergoing elective colorectal resection. The patients were monitored continuously for subcutaneous...... without epidural blockade and 15 (10-20) min with blockade (P surgery....
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Laser absorption spectroscopy of oxygen confined in highly porous hollow sphere xerogel.
Yang, Lin; Somesfalean, Gabriel; He, Sailing
2014-02-10
An Al2O3 xerogel with a distinctive microstructure is studied for the application of laser absorption spectroscopy of oxygen. The xerogel has an exceptionally high porosity (up to 88%) and a large pore size (up to 3.6 µm). Using the method of gas-in-scattering media absorption spectroscopy (GASMAS), a long optical path length (about 3.5m) and high enhancement factor (over 300 times) are achieved as the result of extremely strong multiple-scattering when the light is transmitted through the air-filled, hollow-sphere alumina xerogel. We investigate how the micro-physical feature influences the optical property. As part of the optical sensing system, the material's gas exchange dynamics are also experimentally studied.
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Mechanisms for regulating oxygen toxicity in phytophagous insects.
Ahmad, S; Pardini, R S
1990-01-01
The antioxidant enzymatic defense of insects for the regulation of oxygen toxicity was investigated. Insect species examined were lepidopterous larvae of the cabbage looper (Trichoplusia ni), southern armyworm (Spodoptera eridania), and black swallowtail (Papilio polyxenes). These phytophagous species are subject to both endogenous and exogenous sources of oxidative stress from toxic oxygen radicals, hydrogen peroxide (H2O2) and lipid peroxides (LOOH). In general, the constitutive levels of the enzymes superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GT), and its peroxidase activity (GTpx), and glutathione reductase (GR), correlate well with natural feeding habits of these insects and their relative susceptibility to prooxidant plant allelochemicals, quercetin (a flavonoid), and xanthotoxin (a photoactive furanocoumarin). Induction of SOD activity which rapidly destroys superoxide radicals, appears to be the main response to dietary prooxidant exposure. A unique observation includes high constitutive activity of CAT and a broader subcellular distribution in all three insects than observed in most mammalian species. These attributes of CAT appear to be important in the prevention of excessive accumulation of cytotoxic H2O2. Unlike mammalian species, insects possess very low levels of a GPOX-like activity toward H2O2. Irrefutable proof that this activity is due to a selenium-dependent GPOX found in mammals, is lacking at this time. However, the activity of selenium-independent GTpx is unusually high in insects, suggesting that GTpx and not GPOX plays a prominent role in scavenging deleterious LOOHs. The GSSG generated from the GPOX and GTpx reactions may be reduced to GSH by GR activity. A key role of SOD in protecting insects from prooxidant toxicity was evident when its inhibition resulted in enhanced toxicity towards prooxidants. The role of antioxidant compounds in protecting these insects from toxic forms of oxygen has not been explored in
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Impurities of oxygen in silicon
International Nuclear Information System (INIS)
Gomes, V.M.S.
1985-01-01
The electronic structure of oxygen complex defects in silicon, using molecular cluster model with saturation by watson sphere into the formalism of Xα multiple scattering method is studied. A systematic study of the simulation of perfect silicon crystal and an analysis of the increasing of atom number in the clusters are done to choose the suitable cluster for the calculations. The divacancy in three charge states (Si:V 2 + , Si:V 2 0 , Si:V 2 - ), of the oxygen pair (Si:O 2 ) and the oxygen-vacancy pair (Si:O.V) neighbours in the silicon lattice, is studied. Distortions for the symmetry were included in the Si:V 2 + and Si:O 2 systems. The behavior of defect levels related to the cluster size of Si:V 2 0 and Si:O 2 systems, the insulated oxygen impurity of silicon in interstitial position (Si:O i ), and the complexes involving four oxygen atoms are analysed. (M.C.K.) [pt
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Directory of Open Access Journals (Sweden)
Giulia Bottani
2018-03-01
Full Text Available High flow oxygen with nasal cannula (HFONC is a relatively new mode of oxygen delivery. Advantages of HFONC versus conventional oxygen therapy (COT encompass carbon dioxide washout, generation of a slight positive end-expiratory pressure and maintenance of humidified gas flow through airways. These features are mostly shared with non-invasive mechanical ventilation (NIMV, although with lack of a clearly comparable efficacy. In the last few years, HFONC has gained interest as a third alternative to COT and NIMV in the management of acute hypoxemic respiratory failure in the critically ill patient, both in intensive care units and emergency departments. The aim of this article is to review indications, effects and existing evidence on HFONC, COT and NIMV in the setting of acute hypoxemic respiratory failure.
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Characterization of carbonaceous solids by oxygen chemisorption
Energy Technology Data Exchange (ETDEWEB)
Furimsky, E.; Palmer, A.; Duguay, D.G.; McConnell, D.G.; Henson, D.E.
1988-06-01
Oxygen chemisorption of high and low carbon carbonaceous solids was measured in an electro-microbalance at 200 degrees C in air. A linear correlation between the amount of chemisorbed oxygen and H/C ratio as well as aromaticity was established for the high carbon solids. For the low carbon solids a linear correlation was established between the amount of chemisorbed oxygen and the content of organic matter. Experimental observations are discussed in terms of structural aspects of the solids. Oxygen chemisorption is a suitable technique for a rapid characterization of carbonaceous solids including coal. 15 refs., 7 figs., 3 tabs.
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Liu, Yong-Biao
2012-06-01
Low temperature regular phosphine fumigations under the normal oxygen level and oxygenated phosphine fumigations under superatmospheric oxygen levels were compared for efficacy against the aphid, Nasonovia ribisnigri (Mosley), and effects on postharvest quality of romaine and head lettuce. Low temperature regular phosphine fumigation was effective against the aphid. However, a 3 d treatment with high phosphine concentrations of > or = 2,000 ppm was needed for complete control of the aphid. Oxygen greatly increased phosphine toxicity and significantly reduced both treatment time and phosphine concentration for control of N. ribisnigri. At 1,000 ppm phosphine, 72 h regular fumigations at 6 degrees C did not achieve 100% mortality of the aphid. The 1,000 ppm phosphine fumigation under 60% O2 killed all aphids in 30 h. Both a 72 h regular fumigation with 2,200 ppm phosphine and a 48 h oxygenated fumigation with 1,000 ppm phosphine under 60% O2 were tested on romaine and head lettuce at 3 degrees C. Both treatments achieved complete control of N. ribisnigri. However, the 72 h regular fumigation resulted in significantly higher percentages of lettuce with injuries and significantly lower lettuce internal quality scores than the 48 h oxygenated phosphine fumigation. Although the oxygenated phosphine fumigation also caused injuries to some treated lettuce, lettuce quality remained very good and the treatment is not expected to have a significant impact on marketability of the lettuce. This study demonstrated that oxygenated phosphine fumigation was more effective and less phytotoxic for controlling N. ribisnigri on harvested lettuce than regular phosphine fumigation and is promising for practical use.
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Celebi, H; Bozkirli, F; Günaydin, B; Bilgihan, A
2000-01-01
We report on the use of intravenous (IV) high-dose lidocaine to relieve diabetic neuropathic pain, and the technique's effects on clinical measures of lipid peroxidation. Under continuous electrocardiogram monitoring, IV lidocaine (5 mg kg(-1) in 100 mL saline) was administered over 30 minutes to 7 non-insulin-dependent diabetic patients suffering from neuropathic pain who reported increased pain within the preceding 6 months. This treatment was performed once a week for 1 month. Blood samples were collected from the contralateral limb to determine plasma superoxide dismutase (SOD) and malondialdehyde (MDA) levels on admission and following the final lidocaine administration. Plasma MDA concentrations significantly decreased after the final IV lidocaine treatment (P < .05, paired t-test), whereas SOD levels did not show a statistically significant difference compared with baseline levels. High-dose lidocaine treatment lessens MDA levels, a marker of free-radical-mediated cell damage. This suggests that one of lidocaine's mechanism of action may be its effect on oxygen free radicals, which in turn impacts lipid peroxidation.
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DEFF Research Database (Denmark)
Revsbech, Inge Grønvall
2016-01-01
The aim of this thesis is to broaden the knowledge of molecular mechanisms of adjustment in oxygen (O2) uptake, conduction, delivery and consumption in mammals adapted to extreme conditions. For this end, I have worked with animals living at high altitude as an example of environmental hypoxia...... of the repeatedly found adaptive traits in animals living at high altitude and in hibernating mammals during hibernation compared with the active state. Factors that affect O2 affinity of Hb include temperature, H+/CO2 via the Bohr effect as well as Cl- and organic phosphates, in mammals mainly 2...
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Recombination and detachment in oxygen discharges: the role of metastable oxygen molecules
International Nuclear Information System (INIS)
Gudmundsson, J T
2004-01-01
A global (volume averaged) model of oxygen discharges is used to study the transition from a recombination dominated discharge to a detachment dominated discharge. The model includes the metastable oxygen molecules O 2 (a 1 Δ g ) and O 2 (b 1 Σ g + ) and the three Herzberg states O 2 (A 3 Σ u + , A' 3 Δ u , c 1 Σ u - ). Dissociative attachment of the oxygen molecule in the ground state O 2 ( 3 Σ g - ) and the metastable oxygen molecule O 2 (a 1 Δ g ) are the dominating channels for creation of the negative oxygen ion O - . At high pressures, dissociative attachment of the Herzberg states contributes significantly to the creation of the negative oxygen ion, O - . The detachment by a collision of the metastable oxygen molecule O 2 (b 1 Σ g + ) with the oxygen ion, O - , is a significant loss process for the O - at pressures above 10 mTorr. Its contribution to the loss is more significant at a lower applied power, but at the higher pressures it is always significant. Detachment by collision with O( 3 P) is also an important loss mechanism for O - . We find that ion-ion recombination is the dominating loss process for negative ions in oxygen discharges at low pressures and calculate the critical pressure where the contributions of recombination reactions and detachment reactions are equal. This critical pressure depends on the applied power, increases with applied power and is in the range 5-14 mTorr in the pressure and power range investigated
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ET-1 increases reactive oxygen species following hypoxia and high-salt diet in the mouse glomerulus.
Heimlich, J B; Speed, J S; Bloom, C J; O'Connor, P M; Pollock, J S; Pollock, D M
2015-03-01
This study was designed to determine whether ET-1 derived from endothelial cells contributes to oxidative stress in the glomerulus of mice subjected to a high-salt diet and/or hypoxia. C57BL6/J control mice or vascular endothelial cell ET-1 knockout (VEET KO) mice were subjected to 3-h exposure to hypoxia (8% O₂) and/or 2 weeks of high-salt diet (4% NaCl) prior to metabolic cage assessment of renal function and isolation of glomeruli for the determination of reactive oxygen species (ROS). In control mice, hypoxia significantly increased urinary protein excretion during the initial 24 h, but only in animals on a high-salt diet. Hypoxia increased glomerular ET-1 mRNA expression in control, but not in vascular endothelial cell ET-1 knockout (VEET KO) mice. Under normoxic conditions, mice on a high-salt diet had approx. 150% higher glomerular ET-1 mRNA expression compared with a normal-salt diet (P ET-1 (osmotic pumps) significantly increased the levels of glomerular ROS that were prevented by ETA antagonist treatment. These data suggest that both hypoxia and a high-salt diet increase glomerular ROS production via endothelial-derived ET-1-ETA receptor activation and provide a potential mechanism for ET-1-induced nephropathy. © 2014 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.
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In Situ Bioreduction of Uranium (VI) to Submicromolar Levels and Reoxidation by Dissolved Oxygen
International Nuclear Information System (INIS)
Wu, Weimin; Carley, Jack M.; Luo, Jian; Ginder-Vogel, Matthew A.; Cardenas, Erick; Leigh, Mary Beth; Hwang, Chaichi; Kelly, Shelly D.; Ruan, Chuanmin; Wu, Liyou; Van Nostrand, Joy; Gentry, Terry J.; Lowe, Kenneth Alan; Mehlhorn, Tonia L.; Carroll, Sue L.; Luo, Wensui; Fields, Matthew Wayne; Gu, Baohua; Watson, David B.; Kemner, Kenneth M.; Marsh, Terence; Tiedje, James; Zhou, Jizhong; Fendorf, Scott; Kitanidis, Peter K.; Jardine, Philip M.; Criddle, Craig
2007-01-01
Groundwater within Area 3 of the U.S. Department of Energy (DOE) Environmental Remediation Sciences Program (ERSP) Field Research Center at Oak Ridge, TN (ORFRC) contains up to 135 (micro)M uranium as U(VI). Through a series of experiments at a pilot scale test facility, we explored the lower limits of groundwater U(VI) that can be achieved by in-situ biostimulation and the effects of dissolved oxygen on immobilized uranium. Weekly 2 day additions of ethanol over a 2-year period stimulated growth of denitrifying, Fe(III)-reducing, and sulfate-reducing bacteria, and immobilization of uranium as U(IV), with dissolved uranium concentrations decreasing to low levels. Following sulfite addition to remove dissolved oxygen, aqueous U(VI) concentrations fell below the U.S. Environmental Protection Agency maximum contaminant limit (MCL) for drinking water ( -1 or 0.126 (micro)M). Under anaerobic conditions, these low concentrations were stable, even in the absence of added ethanol. However, when sulfite additions stopped, and dissolved oxygen (4.0-5.5 mg L -1 ) entered the injection well, spatially variable changes in aqueous U(VI) occurred over a 60 day period, with concentrations increasing rapidly from <0.13 to 2.0 (micro)M at a multilevel sampling (MLS) well located close to the injection well, but changing little at an MLS well located further away. Resumption of ethanol addition restored reduction of Fe(III), sulfate, and U(VI) within 36 h. After 2 years of ethanol addition, X-ray absorption near-edge structure spectroscopy (XANES) analyses indicated that U(IV) comprised 60-80% of the total uranium in sediment samples. At the completion of the project (day 1260), U concentrations in MLS wells were less than 0.1 (micro)M. The microbial community at MLS wells with low U(VI) contained bacteria that are known to reduce uranium, including Desulfovibrio spp. and Geobacter spp., in both sediment and groundwater. The dominant Fe(III)-reducing species were Geothrix spp
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Intra-particle oxygen diffusion limitation in solid-state fermentation
Oostra, J.; Comte, le E.P.; Heuvel, van den J.C.; Tramper, J.; Rinzema, A.
2001-01-01
Oxygen limitation in solid-state fermentation (SSF) has been the topic of modeling studies, but thus far, there has been no experimental elucidation on oxygen-transfer limitation at the particle level. Therefore, intra-particle oxygen transfer was experimentally studied in cultures of Rhizopus
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CSIR Research Space (South Africa)
Zheng, H
2010-08-31
Full Text Available Alloyed electrocatalysts such as PtNi/C[1-2], PtCo/C[3], PtCr/C[4], PtFe/C [5-6], and non-alloyed Pt-TiO2/C were reportedly investigated for methanol tolerance during Oxygen reduction reaction (ORR). The high methanol tolerance...
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Neunhäuserer, Daniel; Steidle-Kloc, Eva; Weiss, Gertraud; Kaiser, Bernhard; Niederseer, David; Hartl, Sylvia; Tschentscher, Marcus; Egger, Andreas; Schönfelder, Martin; Lamprecht, Bernd; Studnicka, Michael; Niebauer, Josef
2016-11-01
Physical exercise training is an evidence-based treatment in chronic obstructive pulmonary disease, and patients' peak work rate is associated with reduced chronic obstructive pulmonary disease mortality. We assessed whether supplemental oxygen during exercise training in nonhypoxemic patients with chronic obstructive pulmonary disease might lead to superior training outcomes, including improved peak work rate. This was a randomized, double-blind, controlled, crossover trial. Twenty-nine patients with chronic obstructive pulmonary disease (aged 63.5 ± 5.9 years; forced expiratory volume in 1 second percent predicted, 46.4 ± 8.6) completed 2 consecutive 6-week periods of endurance and strength training with progressive intensity, which was performed 3 times per week with supplemental oxygen or compressed medical air (flow via nasal cannula: 10 L/min). Each session of electrocardiography-controlled interval cycling lasted 31 minutes and consisted of a warm-up, 7 cycles of 1-minute intervals at 70% to 80% of peak work rate alternating with 2 minutes of active recovery, and final cooldown. Thereafter, patients completed 8 strength-training exercises of 1 set each with 8 to 15 repetitions to failure. Change in peak work rate was the primary study end point. The increase in peak work rate was more than twice as high when patients exercised with supplemental oxygen compared with medical air (0.16 ± 0.02 W/kg vs 0.07 ± 0.02 W/kg; P work rate was 39.1% of the overall training effect, whereas it had no influence on strength gain (P > .1 for all exercises). We report that supplemental oxygen in nonhypoxemic chronic obstructive pulmonary disease doubled the effect of endurance training but had no effect on strength gain. Copyright © 2016 Elsevier Inc. All rights reserved.
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The impact of oxygen on the final alcohol content of wine fermented by a mixed starter culture.
Morales, Pilar; Rojas, Virginia; Quirós, Manuel; Gonzalez, Ramon
2015-05-01
We have developed a wine fermentation procedure that takes advantage of the metabolic features of a previously characterized Metschnikowia pulcherrima strain in order to reduce ethanol production. It involves the use of M. pulcherrima/Saccharomyces cerevisiae mixed cultures, controlled oxygenation conditions during the first 48 h of fermentation, and anaerobic conditions thereafter. The influence of different oxygenation regimes and initial inoculum composition on yeast physiology and final ethanol content was studied. The impact of oxygenation on yeast physiology goes beyond the first aerated step and influences yields and survival rates during the anaerobic stage. The activity of M. pulcherrima in mixed oxygenated cultures resulted in a clear reduction in ethanol yield, as compared to S. cerevisiae. Despite relatively low initial cell numbers, S. cerevisiae always predominated in mixed cultures by the end of the fermentation process. Strain replacement was faster under low oxygenation levels. M. pulcherrima confers an additional advantage in terms of dissolved oxygen, which drops to zero after a few hours of culture, even under highly aerated conditions, and this holds true for mixed cultures. Alcohol reduction values about 3.7 % (v/v) were obtained for mixed cultures under high aeration, but they were associated to unacceptable volatile acidity levels. In contrast, under optimized conditions, only 0.35 g/L acetic acid was produced, for an alcohol reduction of 2.2 % (v/v), and almost null dissolved oxygen during the process.
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Schmidt, Matthieu; Stewart, Claire; Bailey, Michael; Nieszkowska, Ania; Kelly, Joshua; Murphy, Lorna; Pilcher, David; Cooper, D James; Scheinkestel, Carlos; Pellegrino, Vincent; Forrest, Paul; Combes, Alain; Hodgson, Carol
2015-03-01
To describe mechanical ventilation settings in adult patients treated for an acute respiratory distress syndrome with extracorporeal membrane oxygenation and assess the potential impact of mechanical ventilation settings on ICU mortality. Retrospective observational study. Three international high-volume extracorporeal membrane oxygenation centers. A total of 168 patients treated with extracorporeal membrane oxygenation for severe acute respiratory distress syndrome from January 2007 to January 2013. We analyzed the association between mechanical ventilation settings (i.e. plateau pressure, tidal volume, and positive end-expiratory pressure) on ICU mortality using multivariable logistic regression model and Cox-proportional hazards model. We obtained detailed demographic, clinical, daily mechanical ventilation settings and ICU outcome data. One hundred sixty-eight patients (41 ± 14 years old; PaO2/FIO2 67 ± 19 mm Hg) fulfilled our inclusion criteria. Median duration of extracorporeal membrane oxygenation and ICU stay were 10 days (6-18 d) and 28 days (16-42 d), respectively. Lower positive end-expiratory pressure levels and significantly lower plateau pressures during extracorporeal membrane oxygenation were used in the French center than in both Australian centers (23.9 ± 1.4 vs 27.6 ± 3.7 and 27.8 ± 3.6; p Protective mechanical ventilation strategies were routinely used in high-volume extracorporeal membrane oxygenation centers. However, higher positive end-expiratory pressure levels during the first 3 days on extracorporeal membrane oxygenation support were independently associated with improved survival. Further prospective trials on the optimal mechanical ventilation strategy during extracorporeal membrane oxygenation support are warranted.
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Experimental Research Into High Barometric Oxygen Prevention of Guinea Pig Hearing Loss,
1992-08-28
PREVENTION OF GUINEA PIG HEARING LOSS by Yin Jiacai, Sun Fang ren, et al. DTIC MLECTE •<• EP 2 9 1992 Approved for public release, Distribution unlimited...PREVENTION OF GUINEA PIG HEARING LOSS By: Yin Jiacai, Sun Fang ren, et al. English pages: 9 Source: Chung-Hua I Shueh Tsa Chih, Vol. 65, Nr. 11, Nov.eember...Distributionf._DL~~~t .•b • / or __ Dlist szeccat .lef ’ ~1 EXPERIMENTAL RESEARCH INTO HIGH BAROMETRIC OXYGEN PREVENTION OF GUINEA PIG HEARING LOSS BY: Yin
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Zhang, Hong-Tao; Zhan, Xiao-Bei; Zheng, Zhi-Yong; Wu, Jian-Rong; Yu, Xiao-Bin; Jiang, Yun; Lin, Chi-Chung
2011-07-01
Expression at the mRNA level of ten selected genes in Agrobacterium sp. ATCC 31749 under various dissolved oxygen (DO) levels during curdlan fermentation related to electron transfer chain (ETC), tricarboxylic acid (TCA) cycle, peptidoglycan/lipopolysaccharide biosynthesis, and uridine diphosphate (UDP)-glucose biosynthesis were determined by qRT-PCR. Experiments were performed at DO levels of 30%, 50%, and 75%, as well as under low-oxygen conditions. The effect of high cell density on transcriptional response of the above genes under low oxygen was also studied. Besides cytochrome d (cyd A), the transcription levels of all the other genes were increased at higher DO and reached maximum at 50% DO. Under 75% DO, the transcriptional levels of all the genes were repressed. In addition, transcription levels of icd, sdh, cyo A, and fix N genes did not exhibit significant fluctuation with high cell density culture under low oxygen. These results suggested a mechanism for DO regulation of curdlan synthesis through regulation of transcriptional levels of ETCs, TCA, and UDP-glucose synthesis genes during curdlan fermentation. To our knowledge, this is the first report that DO concentration apparently regulates curdlan biosynthesis in Agrobacterium sp. ATCC 31749 providing essential lead for the optimization of the fermentation at the industrial scale.
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Oxygen dynamics in the aftermath of the Great Oxidation of Earth’s atmosphere
DEFF Research Database (Denmark)
Canfield, Donald Eugene; Ngombi-Pemba, Lauriss; Hammarlund, Emma
2013-01-01
-oxygenated deep waters whereas the youngest were deposited in euxinic waters, which were globally extensive. These fluctuations in oxygenation were likely driven by the comings and goings of the Lomagundi carbon isotope excursion, the longest–lived positive δ13C excursion in Earth history, generating a huge......The oxygen content of Earth’s atmosphere has varied greatly through time, progressing from exceptionally low levels before about 2.3 billion years ago, to much higher levels afterward. In the absence of better information, we usually view the progress in Earth’s oxygenation as a series of steps...... oxygen source to the atmosphere. As the Lomagundi event waned, the oxygen source became a net oxygen sink as Lomagundi organic matter became oxidized, driving oxygen to low levels; this state may have persisted for 200 million years....
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Oxygen - A Four Billion Year History
DEFF Research Database (Denmark)
Canfield, Donald Eugene
of fields, including geology, paleontology, geochemistry, biochemistry, animal physiology, and microbiology, to explain why our oxygenated Earth became the ideal place for life. Describing which processes, both biological and geological, act to control oxygen levels in the atmosphere, Canfield traces...... guides readers through the various lines of scientific evidence, considers some of the wrong turns and dead ends along the way, and highlights the scientists and researchers who have made key discoveries in the field. Showing how Earth's atmosphere developed over time, Oxygen takes readers...
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Hidalgo, P.; Escribano, R.
2015-12-01
A shallow oxygen minimum zone (OMZ) is a critical component in the coastal upwelling ecosystem off Chile. This OMZ causes oxygen-deficient water entering the photic layer and affecting plankton communities having low tolerance to hypoxia. Variable, and usually species-dependent, responses of zooplankton to hypoxia condition can be found. Most dominant species avoid hypoxia by restricting their vertical distribution, while others can temporarily enter and even spent part of their life cycle within the OMZ. Whatever the case, low-oxygen conditions appear to affect virtually all vital rates of zooplankton, such as mortality, fecundity, development and growth and metabolism, and early developmental stages seem more sensitive, with significant consequences for population and community dynamics. For most study cases, these effects are negative at individual and population levels. Observations and predictions upon increasing upwelling intensity over the last 20-30 years indicate a gradual shoaling of the OMZ, and so that an expected enhancement of these negative effects of hypoxia on the zooplankton community. Unknown processes of adaptation and community-structure adjustments are expected to take place with uncertain consequences for the food web of this highly productive eastern boundary current ecosystem.
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Aerobic growth at nanomolar oxygen concentrations
DEFF Research Database (Denmark)
Stolper, Daniel Aaron; Revsbech, Niels Peter; Canfield, Donald Eugene
2010-01-01
that Escherichia coli K-12, chosen for its well-understood biochemistry, rapid growth rate, and low-oxygen-affinity terminal oxidase, grows at oxygen levels of ≤ 3 nM, two to three orders of magnitude lower than previously observed for aerobes. Our study expands both the environmental range and temporal history...... of aerobic organisms....
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Nordøy, Erling S; Lager, Anne R; Schots, Pauke C
2017-12-01
The aim of this study was to monitor seasonal changes in stable isotopes of pool freshwater and harp seal ( Phoca groenlandica ) body water, and to study whether these potential seasonal changes might bias results obtained using the doubly labelled water (DLW) method when measuring energy expenditure in animals with access to freshwater. Seasonal changes in the background levels of deuterium and oxygen-18 in the body water of four captive harp seals and in the freshwater pool in which they were kept were measured over a time period of 1 year. The seals were offered daily amounts of capelin and kept under a seasonal photoperiod of 69°N. Large seasonal variations of deuterium and oxygen-18 in the pool water were measured, and the isotope abundance in the body water showed similar seasonal changes to the pool water. This shows that the seals were continuously equilibrating with the surrounding water as a result of significant daily water drinking. Variations in background levels of deuterium and oxygen-18 in freshwater sources may be due to seasonal changes in physical processes such as precipitation and evaporation that cause fractionation of isotopes. Rapid and abrupt changes in the background levels of deuterium and oxygen-18 may complicate calculation of energy expenditure by use of the DLW method. It is therefore strongly recommended that analysis of seasonal changes in background levels of isotopes is performed before the DLW method is applied on (free-ranging) animals, and to use a control group in order to correct for changes in background levels. © 2017. Published by The Company of Biologists Ltd.
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Cretenet, Marina; Le Gall, Gwenaëlle; Wegmann, Udo; Even, Sergine; Shearman, Claire; Stentz, Régis; Jeanson, Sophie
2014-12-03
Lactococcus lactis is the most used species in the dairy industry. Its ability to adapt to technological stresses, such as oxidative stress encountered during stirring in the first stages of the cheese-making process, is a key factor to measure its technological performance. This study aimed to understand the response to oxidative stress of Lactococcus lactis subsp. cremoris MG1363 at the transcriptional and metabolic levels in relation to acidification kinetics and growth conditions, especially at an early stage of growth. For those purposes, conditions of hyper-oxygenation were initially fixed for the fermentation. Kinetics of growth and acidification were not affected by the presence of oxygen, indicating a high resistance to oxygen of the L. lactis MG1363 strain. Its resistance was explained by an efficient consumption of oxygen within the first 4 hours of culture, leading to a drop of the redox potential. The efficient consumption of oxygen by the L. lactis MG1363 strain was supported by a coherent and early adaptation to oxygen after 1 hour of culture at both gene expression and metabolic levels. In oxygen metabolism, the over-expression of all the genes of the nrd (ribonucleotide reductases) operon or fhu (ferrichrome ABC transports) genes was particularly significant. In carbon metabolism, the presence of oxygen led to an early shift at the gene level in the pyruvate pathway towards the acetate/2,3-butanediol pathway confirmed by the kinetics of metabolite production. Finally, the MG1363 strain was no longer able to consume oxygen in the stationary growth phase, leading to a drastic loss of culturability as a consequence of cumulative stresses and the absence of gene adaptation at this stage. Combining metabolic and transcriptomic profiling, together with oxygen consumption kinetics, yielded new insights into the whole genome adaptation of L. lactis to initial oxidative stress. An early and transitional adaptation to oxidative stress was revealed for L
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Directory of Open Access Journals (Sweden)
Sara Diab
2014-01-01
Full Text Available Bronchoscopy is an important diagnostic and therapeutic intervention for a variety of patients displaying pulmonary pathology. The heterogeneity of the patients undergoing bronchoscopy affords a challenge for providing minimal and safe respiratory support during anesthesia. Currently, options are intubation and general anesthesia versus frequently inadequate sedation or local anaesthesia with low flow oxygen through nasal prongs or mouthpiece. The advent of high flow nasal cannula allows the clinician to have a “middle man” that allows high flow oxygen delivery as well as a degree of respiratory support, which in some cases has been noted to be between 3 and 4 cm of continuous positive airway pressure-like effect. There are minimal data analyzing the use of high flow nasal cannula during anesthesia for bronchoscopy. We present a case report of orthotropic lung transplant recipient undergoing diagnostic bronchoscopy whilst being supported with high flow nasal oxygen in the intensive care unit.
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Modification of radiation-induced DNA lesions by oxygen
International Nuclear Information System (INIS)
Meyn, R.E.; Jenkins, W.T.
1984-01-01
The efficiency of DNA strand break production by radiation under aerated and hypoxic conditions was determined in CHO cells using the technique of alkaline elution. The resulting oxygen enhancement ratio was surprisingly high, 7.8. When the pH of the elution was increased from 12.1, the normally used pH, to 12.8, a substantial increase in the strand breaks produced in the hypoxic cells was observed, resulting in an OER of 4.8. This difference in susceptibility of DNA strand break detection as a function of pH suggested a difference in the type of lesions produced in DNA when irradiated under aerated and hypoxic conditions. Further experiments to examine the DNA-protein crosslinks produced by radiation suggested that the apparent lower level of strand breaks in hypoxic cells may be due to a higher level of DNA-protein crosslinks produced under hypoxic conditions. Thus, oxygen may not only act by modifying the quantity of radiation-induced DNA lesions but may also cause qualitative changes. If the different types of DNA lesions have different contributions to lethality, the OER for cell survival may represent a complex composite of these changes at the molecular level
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DEFF Research Database (Denmark)
Fuglø, Dan; Pedersen, Henrik; Rostrup, Egill
2012-01-01
in different occipital and extraoccipital cortical areas not explained by the boxcar regressor. The results suggest that the P1-N2 regressor is the best EEG-based regressor to model the visual paradigm, but when looking for additional effects like habituation or attention modulation that cannot be modeled......To compare different electroencephalography (EEG)-based regressors and their ability to predict the simultaneously recorded blood oxygenation level dependent response during blocked visual stimulation, simultaneous EEG-functional magnetic resonance imaging in 10 healthy volunteers was performed....... The performance of different single-trial EEG regressors was compared in terms of predicting the measured blood oxygenation level dependent response. The EEG-based regressors were the amplitude and latency of the primary positive (P1) and negative (N2) peaks of the visual evoked potential, the combined P1-N2...
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Oxygen dependency of porfiromycin cytotoxicity
International Nuclear Information System (INIS)
Marshall, R.S.; Rauth, A.M.
1987-01-01
The authors determined the oxygen dependency of toxicity for the bioreductive alkylating agents mitomycin C (MMC) and porfiromycin (PM) to investigate whether the toxicities of these agents increase in the range of oxygen tensions over which cells become increasingly radioresistant. In the present work the oxygen dependency of PM in CHO cells was determined by assaying survival as a function of time of exposure to 1.0 μg/ml PM under various known levels of oxygen. While PM demonstrated preferential hypoxic cell toxicity, aerobic cell survival was reduced ten-fold after five hours of exposure. Conversely, PM toxicity after a five hour hypoxic exposure to <0.001% oxygen appeared to be greater than that observed for similar MMC exposures, suggesting that PM may be more selective than MMC in killing hypoxic rather than aerobic cells. The authors are currently investigating this preferential toxicity in two human cell lines, one of which is resistant to these agents. At present, these observations suggest that PM may be more effective than MMC at destroying tumour cells in regions of intermediate and low oxygen tensions which may survive radiotherapy, though the range of oxygen tensions which mediate toxicity is similar for both agents
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Non-Fermi Liquids as Highly Active Oxygen Evolution Reaction Catalysts.
Hirai, Shigeto; Yagi, Shunsuke; Chen, Wei-Tin; Chou, Fang-Cheng; Okazaki, Noriyasu; Ohno, Tomoya; Suzuki, Hisao; Matsuda, Takeshi
2017-10-01
The oxygen evolution reaction (OER) plays a key role in emerging energy conversion technologies such as rechargeable metal-air batteries, and direct solar water splitting. Herein, a remarkably low overpotential of ≈150 mV at 10 mA cm -2 disk in alkaline solutions using one of the non-Fermi liquids, Hg 2 Ru 2 O 7 , is reported. Hg 2 Ru 2 O 7 displays a rapid increase in current density and excellent durability as an OER catalyst. This outstanding catalytic performance is realized through the coexistence of localized d-bands with the metallic state that is unique to non-Fermi liquids. The findings indicate that non-Fermi liquids could greatly improve the design of highly active OER catalysts.
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Hydrogen-Enhanced Lunar Oxygen Extraction and Storage Using Only Solar Power
Burton, rodney; King, Darren
2013-01-01
oxidation of the shielding and HE, and reacting with the oxygen to form water vapor. The water vapor is filtered through solid regolith to remove unwanted extraction byproducts, and then condensed to a liquid state and stored at 300 to 325 K. Conversion to usable oxygen is achieved by pumping liquid water into a high-pressure electrolyzer, storing the gaseous oxygen at high pressure for use, and diverting the hydrogen back to the reactor or to storage. The results from this design effort show that this oxygen-generating concept can be developed in an efficient system with low specific mass. Advantages include use of regolith as an oxygen source, filter, and thermal insulator. The system can be tested in Earth gravity and can be expected to operate similarly in lunar gravity. The system is scalable, either by increasing the power level and output of a standard module, or by employing multiple modules.
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Directory of Open Access Journals (Sweden)
Yuri Kriel
Full Text Available High intensity interval training (HIIT has been proposed as a time-efficient format of exercise to reduce the chronic disease burden associated with sedentary behaviour. Changes in oxygen utilisation at the local tissue level during an acute session of HIIT could be the primary stimulus for the health benefits associated with this format of exercise. The recovery periods of HIIT effect the physiological responses that occur during the session. It was hypothesised that in sedentary individuals, local and systemic oxygen utilisation would be higher during HIIT interspersed with active recovery periods, when compared to passive recovery periods.Twelve sedentary males (mean ± SD; age 23 ± 3 yr completed three conditions on a cycle ergometer: 1 HIIT with passive recovery periods between four bouts (HIITPASS 2 HIIT with active recovery periods between four bouts (HIITACT 3 HIITACT with four HIIT bouts replaced with passive periods (REC. Deoxygenated haemoglobin (HHb in the vastus lateralis (VL and gastrocnemius (GN muscles and the pre-frontal cortex (FH, oxygen consumption (VO2, power output and heart rate (HR were measured continuously during the three conditions.There was a significant increase in HHb at VL during bouts 2 (p = 0.017, 3 (p = 0.035 and 4 (p = 0.035 in HIITACT, compared to HIITPASS. Mean power output was significantly lower in HIITACT, compared to HIITPASS (p < 0.001. There was a significant main effect for site in both HIITPASS (p = 0.029 and HIITACT (p = 0.005. There were no significant differences in VO2 and HR between HIITPASS and HIITACT.The increase in HHb at VL and the lower mean power output during HIITACT could indicate that a higher level of deoxygenation contributes to decreased mechanical power in sedentary participants. The significant differences in HHb between sites indicates the specificity of oxygen utilisation.