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Sample records for high oxygen tension

  1. Optic nerve oxygen tension

    la Cour, M; Kiilgaard, Jens Folke; Eysteinsson, T

    2000-01-01

    To investigate the influence of acute changes in intraocular pressure on the oxygen tension in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500 mg of the carbonic anhydrase inhibitor dorzolamide.......To investigate the influence of acute changes in intraocular pressure on the oxygen tension in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500 mg of the carbonic anhydrase inhibitor dorzolamide....

  2. Optic nerve oxygen tension

    Kiilgaard, Jens Folke; Pedersen, D B; Eysteinsson, T

    2004-01-01

    The authors have previously reported that carbonic anhydrase inhibitors such as acetazolamide and dorzolamide raise optic nerve oxygen tension (ONPO(2)) in pigs. The purpose of the present study was to investigate whether timolol, which belongs to another group of glaucoma drugs called beta...

  3. Mitochondrial Respiration and Oxygen Tension.

    Shaw, Daniel S; Meitha, Karlia; Considine, Michael J; Foyer, Christine H

    2017-01-01

    Measurements of respiration and oxygen tension in plant organs allow a precise understanding of mitochondrial capacity and function within the context of cellular oxygen metabolism. Here we describe methods that can be routinely used for the isolation of intact mitochondria, and the determination of respiratory electron transport, together with techniques for in vivo determination of oxygen tension and measurement of respiration by both CO 2 production and O 2 consumption that enables calculation of the respiratory quotient [CO 2 ]/[O 2 ].

  4. Multibreath alveolar oxygen tension imaging.

    Clapp, Justin; Hamedani, Hooman; Kadlecek, Stephen; Xin, Yi; Shaghaghi, Hoora; Siddiqui, Sarmad; Rossman, Milton D; Rizi, Rahim R

    2016-10-01

    This study tested the ability of a multibreath hyperpolarized HP (3) He MRI protocol to increase the accuracy of regional alveolar oxygen tension (PA O2 ) measurements by lessening the influence of gas-flow artifacts. Conventional single-breath PA O2 measurement has been susceptible to error induced by intervoxel gas flow, particularly when used to study subjects with moderate-to-severe chronic obstructive pulmonary disease (COPD). Both single-breath and multibreath PA O2 imaging schemes were implemented in seven human subjects (one healthy, three asymptomatic smokers, and three COPD). The number and location of voxels with nonphysiologic PA O2 values generated by intervoxel gas flow were compared between the two protocols. The multibreath scheme resulted in a significantly lower total percentage of nonphysiologic PA O2 values (6.0%) than the single-breath scheme (13.7%) (P = 0.006). PA O2 maps showed several patterns of gas-flow artifacts that were present in the single-breath protocol but mitigated by the multibreath approach. Multibreath imaging also allowed for the analysis of slow-filling areas that presented no signal after a single breath. A multibreath approach enhances the accuracy and completeness of noninvasive PA O2 measurement by significantly lessening the proportion of nonphysiologic values generated by intervoxel gas flow. Magn Reson Med 76:1092-1101, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  5. Oxygen tension level and human viral infections

    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.

  6. Transcutaneous oxygen tension in imminent foot gangrene

    Tønnesen, K H

    1978-01-01

    Transcutaneous oxygen tension at 44 degree C and maximal isotope clearance (90m Tc-pretechnetate + histramine) just proximal to the 1st toe and systolic toe blood pressure (strain gauge) were studied on a tilt table in patients with various degrees of obstructive arteriosclerotic disease. In legs...

  7. 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.

  8. Stimulation of growth of the human gastric pathogen Helicobacter pylori by atmospheric level of oxygen under high carbon dioxide tension

    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.

  9. Effects of Low and High Oxygen Tensions and Related Respiratory Conditions on Visual Performance: A Literature Review

    1988-07-01

    and of the same subject after a diet that made him deficient in Vitamin A. They used only one healthy well-trained observer. Measurementv of...background intensity. The authors do not discuss hypoxia changes in some other visual process, but this improvement above 15,000 feet may reflect hypo ...these studies, Gellhorn and Spiesman (1935) induced caloric nystagmus while subjects breathed mixtures high in CO2 and low in oxygen, and also after

  10. Dorzolamide increases retinal oxygen tension after branch retinal vein occlusion

    Noergaard, Michael Hove; Bach-Holm, Daniella; Scherfig, Erik

    2008-01-01

    To study the effect of dorzolamide on the preretinal oxygen tension (RPO(2)) in retinal areas affected by experimental branch retinal vein occlusion (BRVO) in pigs.......To study the effect of dorzolamide on the preretinal oxygen tension (RPO(2)) in retinal areas affected by experimental branch retinal vein occlusion (BRVO) in pigs....

  11. Low physiologic oxygen tensions reduce proliferation and differentiation of human multipotent mesenchymal stromal cells

    Handgretinger Rupert

    2010-01-01

    Full Text Available Abstract Background Human multipotent mesenchymal stromal cells (MSC can be isolated from various tissues including bone marrow. Here, MSC participate as bone lining cells in the formation of the hematopoietic stem cell niche. In this compartment, the oxygen tension is low and oxygen partial pressure is estimated to range from 1% to 7%. We analyzed the effect of low oxygen tensions on human MSC cultured with platelet-lysate supplemented media and assessed proliferation, morphology, chromosomal stability, immunophenotype and plasticity. Results After transferring MSC from atmospheric oxygen levels of 21% to 1%, HIF-1α expression was induced, indicating efficient oxygen reduction. Simultaneously, MSC exhibited a significantly different morphology with shorter extensions and broader cell bodies. MSC did not proliferate as rapidly as under 21% oxygen and accumulated in G1 phase. The immunophenotype, however, was unaffected. Hypoxic stress as well as free oxygen radicals may affect chromosomal stability. However, no chromosomal abnormalities in human MSC under either culture condition were detected using high-resolution matrix-based comparative genomic hybridization. Reduced oxygen tension severely impaired adipogenic and osteogenic differentiation of human MSC. Elevation of oxygen from 1% to 3% restored osteogenic differentiation. Conclusion Physiologic oxygen tension during in vitro culture of human MSC slows down cell cycle progression and differentiation. Under physiological conditions this may keep a proportion of MSC in a resting state. Further studies are needed to analyze these aspects of MSC in tissue regeneration.

  12. "Tissue oxygen tension, a determinant of resistance to infection and ...

    "Tissue oxygen tension, a determinant of resistance to infection and healing" - An Inaugural Lecture. K Jönsson. Abstract. An Inaugural Lecture Given in the University of Zimbabwe on 21 June 2001. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT.

  13. Changes in transcutaneous oxygen tension during exercise in pulmonary emphysema.

    Hughes, J A; Gray, B J; Hutchison, D C

    1984-01-01

    Continuous measurements of transcutaneous oxygen tension (tcPO2) were made in 23 patients with radiological evidence of emphysema, at rest and during a maximal progressive exercise test. tcPO2 during the final phase of exercise was compared with tcPO2 at rest; the mean change (exercising minus resting value) in tcPO2 (delta tcPO2) was -0.8 mm Hg (SD 10.5, range -18 to +25) (-0.1 kPa (SD 1.4, range -2.4 to +3.3]. delta tcPO2 was correlated with: resting arterial oxygen tension (PaO2) (r = 0.60...

  14. Oxygen Tension Regulates Human Mesenchymal Stem Cell Paracrine Functions

    Paquet, Joseph; Deschepper, Mickael; Moya, Adrien; Logeart-Avramoglou, Delphine; Boisson-Vidal, Catherine; Petite, Hervé

    2015-01-01

    This study examined the shift of the human mesenchymal stem cell (hMSC) cytokine signature induced by oxygen tension. Conditioned media obtained from hMSCs cultured under near anoxia exhibited significantly enhanced chemotactic and proangiogenic properties and a significant decrease in the inflammatory mediator content. These results elucidate important aspects of using MSCs in regenerative medicine, contribute to improving the efficacy of such therapies, and highlight the interest in using c...

  15. Hemodynamic parameters change earlier than tissue oxygen tension in hemorrhage.

    Pestel, Gunther J; Fukui, Kimiko; Kimberger, Oliver; Hager, Helmut; Kurz, Andrea; Hiltebrand, Luzius B

    2010-05-15

    Untreated hypovolemia results in impaired outcome. This study tests our hypothesis whether general hemodynamic parameters detect acute blood loss earlier than monitoring parameters of regional tissue beds. Eight pigs (23-25 kg) were anesthetized and mechanically ventilated. A pulmonary artery catheter and an arterial catheter were inserted. Tissue oxygen tension was measured with Clark-type electrodes in the jejunal and colonic wall, in the liver, and subcutaneously. Jejunal microcirculation was assessed by laser Doppler flowmetry (LDF). Intravascular volume was optimized using difference in pulse pressure (dPP) to keep dPP below 13%. Sixty minutes after preparation, baseline measurements were taken. At first, 5% of total blood volume was withdrawn, followed by another 5% increment, and then in 10% increments until death. After withdrawal of 5% of estimated blood volume, dPP increased from 6.1% +/- 3.0% to 20.8% +/- 2.7% (P < 0.01). Mean arterial pressure (MAP), mean pulmonary artery pressure (PAP) and pulmonary artery occlusion pressure (PAOP) decreased with a blood loss of 10% (P < 0.01). Cardiac output (CO) changed after a blood loss of 20% (P < 0.05). Tissue oxygen tension in central organs, and blood flow in the jejunal muscularis decreased (P < 0.05) after a blood loss of 20%. Tissue oxygen tension in the skin, and jejunal mucosa blood flow decreased (P < 0.05) after a blood loss of 40% and 50%, respectively. In this hemorrhagic pig model systemic hemodynamic parameters were more sensitive to detect acute hypovolemia than tissue oxygen tension measurements or jejunal LDF measurements. Acute blood loss was detected first by dPP. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  16. Renal transplantation induces mitochondrial uncoupling, increased kidney oxygen consumption, and decreased kidney oxygen tension

    Papazova, Diana A.; Friederich-Persson, Malou; Joles, Jaap A.; Verhaar, Marianne C.

    2015-01-01

    Hypoxia is an acknowledged pathway to renal injury and ischemia-reperfusion (I/R) and is known to reduce renal oxygen tension (PO2). We hypothesized that renal I/R increases oxidative damage and induces mitochondrial uncoupling, resulting in increased oxygen consumption and hence kidney

  17. Cerebral Microcirculation and Oxygen Tension in the Human Secondary Cortex

    Linninger, A. A.; Gould, I. G.; Marinnan, T.; Hsu, C.-Y.; Chojecki, M.; Alaraj, A.

    2013-01-01

    The three-dimensional spatial arrangement of the cortical microcirculatory system is critical for understanding oxygen exchange between blood vessels and brain cells. A three-dimensional computer model of a 3 × 3 × 3 mm3 subsection of the human secondary cortex was constructed to quantify oxygen advection in the microcirculation, tissue oxygen perfusion, and consumption in the human cortex. This computer model accounts for all arterial, capillary and venous blood vessels of the cerebral microvascular bed as well as brain tissue occupying the extravascular space. Microvessels were assembled with optimization algorithms emulating angiogenic growth; a realistic capillary bed was built with space filling procedures. The extravascular tissue was modeled as a porous medium supplied with oxygen by advection–diffusion to match normal metabolic oxygen demand. The resulting synthetic computer generated network matches prior measured morphometrics and fractal patterns of the cortical microvasculature. This morphologically accurate, physiologically consistent, multi-scale computer network of the cerebral microcirculation predicts the oxygen exchange of cortical blood vessels with the surrounding gray matter. Oxygen tension subject to blood pressure and flow conditions were computed and validated for the blood as well as brain tissue. Oxygen gradients along arterioles, capillaries and veins agreed with in vivo trends observed recently in imaging studies within experimental tolerances and uncertainty. PMID:23842693

  18. Effect of pneumatic tourniquet on muscle oxygen tension.

    Santavirta, S; Höckerstedt, K; Niinikoski, J

    1978-10-01

    Recent investigations suggest that circulation in a limb can be reduced with a tourniquet to less than 1 per cent of the control limb, or even completely occluded. The development of tissue oxygen tonometry with implanted silastic tubes has provided new possibilities for assessing muscle tissue oxygen tension. In the present work, this method was employed to register the effect of tourniquet blackade on the lower limb muscle PO2 in rabbits. The duration of the tourniquet blockade was 60, 120 and 180 minutes. The baseline muscle PO2 in the tibialis anterior muscle was 22.6 +/- 0.6 mmHg. During the tourniquet blockade the oxygen tension dropped to minimal values between 9.2 +/- 0.5 and 10.7 +/- 0.6 mmHg in these experimental groups, but the tissue microclimate never reached fully anoxic conditions. The rapid response of muscle PO2 to oxygen breathing after release of the blockade suggests that limb microcirculation tolerates tourniquet occlusion well.

  19. Oxygen tension during biofilm growth influences the efficacy antimicrobial agents

    Raquel Pippi ANTONIAZZI

    Full Text Available Abstract Objective To compare the antimicrobial efficacy of a 0.12% chlorhexidine (CHX and herbal green tea (Camellia sinensis solution on established biofilms formed at different oxygen tensions in an in situ model. Method Twenty-five dental students were eligible for the study. In situ devices with standardized enamel specimens (ES facing the palatal and buccal sides were inserted in the mouths of volunteers for a 7 day period. No agent was applied during the first four days. From the fifth day onward, both agents were applied to the test ES group and no agent was applied to the control ES group. After 7 days the ES fragments were removed from the devices, sonicated, plated on agar, and incubated for 24 h at 37 °C to determine and quantify the colony forming units (CFUs. Result CHX had significantly higher efficacy compared to green tea on the buccal (1330 vs. 2170 CFU/µL and palatal (2250 vs. 2520 CFU/µL ES. In addition, intragroup comparisons showed significantly higher efficacy in buccal ES over palatal ES (1330 vs. 2250 CFU/µL for CHX and 2170 vs, 2520 CFU/µL for CV for both solutions. Analysis of the ES controls showed significantly higher biofilm formation in palatal ES compared to buccal ES. Conclusion CHX has higher efficacy than green tea on 4-day biofilms. The efficacy of both agents was reduced for biofilms grown in a low oxygen tension environment. Therefore, the oxygen tension environment seems to influence the efficacy of the tested agents.

  20. Oxygen Tension Regulates Human Mesenchymal Stem Cell Paracrine Functions.

    Paquet, Joseph; Deschepper, Mickael; Moya, Adrien; Logeart-Avramoglou, Delphine; Boisson-Vidal, Catherine; Petite, Hervé

    2015-07-01

    : Mesenchymal stem cells (MSCs) have captured the attention and research endeavors of the scientific world because of their differentiation potential. However, there is accumulating evidence suggesting that the beneficial effects of MSCs are predominantly due to the multitude of bioactive mediators secreted by these cells. Because the paracrine potential of MSCs is closely related to their microenvironment, the present study investigated and characterized select aspects of the human MSC (hMSC) secretome and assessed its in vitro and in vivo bioactivity as a function of oxygen tension, specifically near anoxia (0.1% O2) and hypoxia (5% O2), conditions that reflect the environment to which MSCs are exposed during MSC-based therapies in vivo. In contrast to supernatant conditioned media (CM) obtained from hMSCs cultured at either 5% or 21% of O2, CM from hMSCs cultured under near anoxia exhibited significantly (p mesenchymal stem cell (hMSC) secretome and assessed its in vitro and in vivo biological bioactivity as a function of oxygen tension, specifically near anoxia (0.1% O2) and hypoxia (5% O2), conditions that reflect the environment to which MSCs are exposed during MSC-based therapies in vivo. The present study provided the first evidence of a shift of the hMSC cytokine signature induced by oxygen tension, particularly near anoxia (0.1% O2). Conditioned media obtained from hMSCs cultured under near anoxia exhibited significantly enhanced chemotactic and proangiogenic properties and a significant decrease in the inflammatory mediator content. These findings provide new evidence that elucidates aspects of great importance for the use of MSCs in regenerative medicine, could contribute to improving the efficacy of such therapies, and most importantly highlighted the interest in using conditioned media in therapeutic modalities. ©AlphaMed Press.

  1. Carbonic anhydrase inhibition increases retinal oxygen tension and dilates retinal vessels

    Pedersen, Daniella Bach; Koch Jensen, Peter; la Cour, Morten

    2005-01-01

    Carbonic anhydrase inhibitors (CAIs) increase blood flow in the brain and probably also in the optic nerve and retina. Additionally they elevate the oxygen tension in the optic nerve in the pig. We propose that they also raise the oxygen tension in the retina. We studied the oxygen tension in the...... in the pig retina and optic nerve before and after dorzolamide injection. Also the retinal vessel diameters during carbonic anhydrase inhibition were studied....

  2. A method for volumetric retinal tissue oxygen tension imaging.

    Felder, Anthony E; Wanek, Justin; Teng, Pang-Yu; Blair, Norman P; Shahidi, Mahnaz

    2018-01-01

    Inadequate retinal oxygenation occurs in many vision-threatening retinal diseases, including diabetic retinopathy, retinal vascular occlusions, and age-related macular degeneration. Therefore, techniques that assess retinal oxygenation are necessary to understand retinal physiology in health and disease. The purpose of the current study is to report a method for the three-dimensional (3D) imaging of retinal tissue oxygen tension (tPO 2 ) in rats. Imaging was performed in Long Evans pigmented rats under systemic normoxia (N = 6) or hypoxia (N = 3). A vertical laser line was horizontally scanned on the retina and a series of optical section phase-delayed phosphorescence images were acquired. From these images, phosphorescence volumes at each phase delay were constructed and a 3D retinal tPO 2 volume was generated. Retinal tPO 2 volumes were quantitatively analyzed by generating retinal depth profiles of mean tPO 2 (M tPO2 ) and the spatial variation of tPO 2 (SV tPO2 ). The effects of systemic condition (normoxia/hypoxia) and retinal depth on M tPO2 and SV tPO2 were determined by mixed linear model. Each 3D retinal tPO 2 volume was approximately 500 × 750 × 200 μm (horizontal × vertical × depth) and consisted of 45 en face tPO 2 images through the retinal depth. M tPO2 at the chorioretinal interface was significantly correlated with systemic arterial oxygen tension (P = 0.007; N = 9). There were significant effects of both systemic condition and retinal depth on M tPO2 and SV tPO2 , such that both were lower under hypoxia than normoxia and higher in the outer retina than inner retina (P < 0.001). For the first time, 3D imaging of retinal tPO 2 was demonstrated, with potential future application for assessment of physiological alterations in animal models of retinal diseases.

  3. Oxygen Tension in the Aqueous Humor of Human Eyes under Different Oxygenation Conditions

    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.

  4. Bladder urine oxygen tension for assessing renal medullary oxygenation in rabbits: experimental and modeling studies

    Sgouralis, Ioannis; Kett, Michelle M.; Ow, Connie P. C.; Abdelkader, Amany; Layton, Anita T.; Gardiner, Bruce S.; Smith, David W.; Lankadeva, Yugeesh R.; Evans, Roger G.

    2016-01-01

    Oxygen tension (Po2) of urine in the bladder could be used to monitor risk of acute kidney injury if it varies with medullary Po2. Therefore, we examined this relationship and characterized oxygen diffusion across walls of the ureter and bladder in anesthetized rabbits. A computational model was then developed to predict medullary Po2 from bladder urine Po2. Both intravenous infusion of [Phe2,Ile3,Orn8]-vasopressin and infusion of NG-nitro-l-arginine reduced urinary Po2 and medullary Po2 (8–1...

  5. Oxygen Tension Beneath Scleral Lenses of Different Clearances.

    Giasson, Claude J; Morency, Jeanne; Melillo, Marc; Michaud, Langis

    2017-04-01

    To evaluate the relative partial pressure in oxygen (pO2) at the corneal surface under Boston XO2 scleral lenses (SL) fitted with targeted clearances of 200 and 400 μm (SL200 and SL400). During this prospective study, the right eyes of eight normal subjects were fitted with SL200 and SL400. Clearance, validated after 5 minutes of wear with an optical coherence tomograph, was used with lens thicknesses to calculate transmissibility and estimate pO2. Corneal pO2s were measured with an oxygen electrode after 5 minutes of (1) corneal exposure to calibrating gases with various pO2 or of (2) SL wear. Decays in pO2 were modeled to an exponential. Linear regression between exponent k of these decays and calibrating gas pO2s allowed for the calculation of corneal pO2 under SL. Differences between pO2s beneath SL200 and SL400 were tested with a mixed ANOVA. The estimated transmissibility based on thicknesses and clearances (239.7 ± 34.7; 434.5 ± 33.2 μm) predicted a corneal pO2 of 8.52 ± 0.51 and 6.37 ± 0.28% for SL200 and SL400. These values were close to measured pO2: 9.07 ± 0.86 and 6.19 ± 0.87% (mean ± SEM) (P time, an 18-mm scleral lens fitted with a 400-μm clearance reduces the oxygen tension available to the cornea by 30% compared to a similar lens fitted with a 200-μm clearance after 5 minutes of wear.

  6. Optic nerve oxygen tension in pigs and the effect of carbonic anhydrase inhibitors

    Stefánsson, E; Jensen, P K; Eysteinsson, T

    1999-01-01

    To evaluate how the oxygen tension of the optic nerve (ONP(O)2) is affected by the administration of the carbonic anhydrase inhibitors dorzolamide and acetazolamide and by alterations in oxygen and carbon dioxide in the breathing mixture.......To evaluate how the oxygen tension of the optic nerve (ONP(O)2) is affected by the administration of the carbonic anhydrase inhibitors dorzolamide and acetazolamide and by alterations in oxygen and carbon dioxide in the breathing mixture....

  7. Effect of oxygen tension on bioenergetics and proteostasis in young and old myoblast precursor cells.

    Konigsberg, M; Pérez, V I; Ríos, C; Liu, Y; Lee, S; Shi, Y; Van Remmen, H

    2013-01-01

    In the majority of studies using primary cultures of myoblasts, the cells are maintained at ambient oxygen tension (21% O2), despite the fact that physiological O2 at the tissue level in vivo is much lower (~1-5% O2). We hypothesized that the cellular response in presence of high oxygen concentration might be particularly important in studies comparing energetic function or oxidative stress in cells isolated from young versus old animals. To test this, we asked whether oxygen tension plays a role in mitochondrial bioenergetics (oxygen consumption, glycolysis and fatty acid oxidation) or oxidative damage to proteins (protein disulfides, carbonyls and aggregates) in myoblast precursor cells (MPCs) isolated from young (3-4 m) and old (29-30 m) C57BL/6 mice. MPCs were grown under physiological (3%) or ambient (21%) O2 for two weeks prior to exposure to an acute oxidative insult (H2O2). Our results show significantly higher basal mitochondrial respiration in young versus old MPCs, an increase in basal respiration in young MPCs maintained at 3% O2 compared to cells maintained at 21% O2, and a shift toward glycolytic metabolism in old MPCs grown at 21% O2. H2O2 treatment significantly reduced respiration in old MPCs grown at 3% O2 but did not further repress respiration at 21% O2 in old MPCs. Oxidative damage to protein was higher in cells maintained at 21% O2 and increased in response to H2O2 in old MPCs. These data underscore the importance of understanding the effect of ambient oxygen tension in cell culture studies, in particular studies measuring oxidative damage and mitochondrial function.

  8. Oxygen tension and oocyte density during in vitro maturation affect the in vitro fertilization of bovine oocytes

    Angelo Bertani Giotto

    2015-12-01

    Full Text Available Oocyte maturation is the key factor affecting the fertilization and embryonic development. Factors such as oocyte density and oxygen tension can directly influence the IMV. Thus, the objective of this study was to evaluate the effect of the association of oxygen tensions (5% or 20% with different oocyte densities (1:10?l or 1:20?l in the in vitro maturation (IVM of bovine oocytes on maturation and fertilization rates, ROS production and antioxidant activity. Three experiments were performed with bovine oocytes that were obtained from slaughterhouse ovaries. After selection, the oocytes were randomly distributed in four treatments: 1:10/5%; 1:10/20%; 1:20/5%and 1:20/20% for each experiment. In experiment I, nuclear maturation status and cytoplasmic maturation were evaluated through detection of the first polar body by immunofluorescence and the mitochondrial reorganization assay. In experiment II, ROS production and antioxidant activity were analyzed in oocytes and IVM medium after 24 h of maturation through detection of ROS, reduced glutathione (GSH and Superoxide dismutase activity by spectrofluorimetric methods. In experiment III, fertilization was evaluated through pronucleus formation, sperm penetration with or without decondensation and polyspermy rates by immunofluorescence. In experiment I, the nuclear maturation and cytoplasmic maturation were similar among treatments (P>0.05. In experiment II, reactive oxygen species in oocytes were elevated in treatments with low oxygen tension which was independent of oocyte density (P<0.05. Additionally, ROS levels in IVM medium were higher in treatments with high oocyte density by volume of medium, which was independent of oxygen tension (P<0.05. In Experiment III, the fertilization and penetration rates were higher in the treatment with 20% oxygen tension and high oocyte density (P<0.05. Furthermore, a high incidence of polyspermy was observed in groups with high oxygen tension and low oocyte

  9. Simultaneous Monitoring of Vascular Oxygenation and Tissue Oxygen Tension of Breast Tumors Under Hyperbaric Oxygen Exposure

    2008-04-01

    28. Alagoz, T., R. Buller, B. Anderson, K. Terrell , R...and oxygenation Ann . New Acad. Sci. 838 29–45 Chapman J D, Stobbe C C, Arnfield M R, Santus R, Lee J and McPhee M S 1991 Oxygen dependency of tumor

  10. Enhanced proliferation and dopaminergic differentiation of ventral mesencephalic precursor cells by synergistic effect of FGF2 and reduced oxygen tension

    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...

  11. Oxygen tension in transplanted mouse osteosarcomas during fractionated high-LET- and low-LET radiotherapy - predictive aspects for choosing beam quality?

    Auberger, T.; Thuerriegel, B.; Freude, T.; Weissfloch, L.; Kneschaurek, P.; Molls, M.; Senekowitsch-Schmidtke, R.; Wagner, F.M.

    1999-01-01

    Murine OTS64 - osteosarcomas were tranplanted in 102 balb-C mice and irradiated by 36 Gy of photons in fractions of 3 Gy five times a week (group P-36/3) or by 12 Gy of reactor fission neutrons in fractions of 2 Gy two times a week (group N-12/2). Irradiations started at a tumor volume of 500 to 600 mm 3 . A third group received no radiotherapy, but all investigations (group CG). Tumor volume and tumor oxygenation were measured once a week under therapy and during three weeks after therapy. For in vivo-evaluation of oxygen status a computerized polarographic needle electrode system (KIMOC pO 2 histograph, Eppendorf) was used. The median pO 2 and the hypoxic fraction (pO 2 values 2 decreased from 20 mm to 8 mm Hg and the hypoxic fraction increased from 7% to 31%. After fractionated photon therapy a growth delay of three weeks was observed. Six weeks after beginning of the irradiation the median tumor volume had been doubled again. After fission neutron therapy growth delay continued until the end of the follow-up period. In both of the irradiated groups a significant decrease of median pO 2 values and an increase of the hypoxic fraction were observed under radiotherapy. Hypoxia was more intensive after neutrons with a decrease of the median pO 2 from 20 mm Hg to 1 mm Hg vs. 10 mm Hg after photon therapy and with an increase of the hypoxic fraction from 7% to 78% vs. 36% respectively. Two weeks after the end of therapy the median pO 2 and the hypoxic fraction of both treated groups reached the levels prior to irradiation indicating a complete reoxygenation. (orig.)

  12. Simultaneous Monitoring of Vascular Oxygenation and Tissue Oxygen Tension of Breast Tumors Under Hyperbaric Oxygen Exposure

    Xia, Mengna

    2005-01-01

    The goals of the study in the first stage are 1) to develop a mathematic model by which we can derive tumor blood flow and metabolic rate of oxygen from hemoglobin concentration during interventions, 2...

  13. In vivo mitochondrial oxygen tension measured by a delayed fluorescence lifetime technique

    Mik, Egbert G.; Johannes, Tanja; Zuurbier, Coert J.; Heinen, Andre; Houben-Weerts, Judith H. P. M.; Balestra, Gianmarco M.; Stap, Jan; Beek, Johan F.; Ince, Can

    2008-01-01

    Mitochondrial oxygen tension (mitoPO(2)) is a key parameter for cellular function, which is considered to be affected under various pathophysiological circumstances. Although many techniques for assessing in vivo oxygenation are available, no technique for measuring mitoPO(2) in vivo exists. Here we

  14. Radioprotection of mouse skin by WR-2721: the critical influence of oxygen tension

    Denekamp, J.; Michael, B.D.; Rojas, A.; Stewart, F.A.

    1982-01-01

    The epidermal clone assay has been used to study the radioprotective effect of WR-2721 on mouse skin under different conditions of oxygenation and under anoxia. The skin has shown a progressive decrease in sensitivity as the inspired gas has changed from 100% oxygen towards 0% oxygen. Compared with mice breathning 100% oxygen, those breathing air are partially protected. The inspired oxygen concentration to give half the full oxygen effect is 10-12%. The radioprotecton observed with 400 mg/kg WR-2721 is markedly dependent on the ambient oxygen concentration. The protection factor is 1.1 or less in mice breathing 5%, 1% or 0% oxygen. Protection is maximal (1.95) in air and in 50% oxygen and diminishes to 1.6 at higher oxygen tensions

  15. Bladder urine oxygen tension for assessing renal medullary oxygenation in rabbits: experimental and modeling studies

    Sgouralis, Ioannis; Kett, Michelle M.; Ow, Connie P. C.; Abdelkader, Amany; Layton, Anita T.; Gardiner, Bruce S.; Smith, David W.; Lankadeva, Yugeesh R.

    2016-01-01

    Oxygen tension (Po2) of urine in the bladder could be used to monitor risk of acute kidney injury if it varies with medullary Po2. Therefore, we examined this relationship and characterized oxygen diffusion across walls of the ureter and bladder in anesthetized rabbits. A computational model was then developed to predict medullary Po2 from bladder urine Po2. Both intravenous infusion of [Phe2,Ile3,Orn8]-vasopressin and infusion of NG-nitro-l-arginine reduced urinary Po2 and medullary Po2 (8–17%), yet had opposite effects on renal blood flow and urine flow. Changes in bladder urine Po2 during these stimuli correlated strongly with changes in medullary Po2 (within-rabbit r2 = 0.87–0.90). Differences in the Po2 of saline infused into the ureter close to the kidney could be detected in the bladder, although this was diminished at lesser ureteric flow. Diffusion of oxygen across the wall of the bladder was very slow, so it was not considered in the computational model. The model predicts Po2 in the pelvic ureter (presumed to reflect medullary Po2) from known values of bladder urine Po2, urine flow, and arterial Po2. Simulations suggest that, across a physiological range of urine flow in anesthetized rabbits (0.1–0.5 ml/min for a single kidney), a change in bladder urine Po2 explains 10–50% of the change in pelvic urine/medullary Po2. Thus, it is possible to infer changes in medullary Po2 from changes in urinary Po2, so urinary Po2 may have utility as a real-time biomarker of risk of acute kidney injury. PMID:27385734

  16. Unusual Growth Phase and Oxygen Tension Regulation of Oxidative Stress Protection Enzymes, Catalase and Superoxide Dismutase, in the Phytopathogen Xanthomonas oryzae pv. oryzae

    Chamnongpol, S.; Mongkolsuk, S.; Vattanaviboon, P.; Fuangthong, M.

    1995-01-01

    The enzymes catalase and superoxide dismutase play major roles in protecting phytopathogenic bacteria from oxidative stress. In Xanthomonas species, these enzymes are regulated by both growth phase and oxygen tension. The highest enzyme levels were detected within 1 h of growth. Continued growth resulted in a decline of both enzyme activities. High oxygen tension was an inducing signal for both enzyme activities. An 80,000-Da monofunctional catalase and a manganese superoxide dismutase were t...

  17. Oxygen tension measurements of tumors growing in mice

    Adam, Markus F.; Dorie, Mary Jo; Brown, J. Martin

    1999-01-01

    Purpose: Clinical studies using the Eppendorf histograph have shown that patients whose tumors have a low pO 2 have worse local control after radiotherapy, and have higher metastatic rates. Because preclinical studies of methods of overcoming, or exploiting, hypoxia generally use transplanted tumors in mice, we have compared the oxygenation of mouse tumors with human tumors to determine the appropriateness of the transplanted mouse model for such preclinical studies. Methods and Materials: We evaluated the oxygenation status of subcutaneous (s.c.) tissue and of 12 intradermally (i.d.)- and 7 s.c.-growing mouse or human transplanted tumors in mice using the Eppendorf histograph, and compared the values obtained with measurements of human head and neck nodes. Results: The normal tissue pO 2 profile of air-breathing mice showed a nearly Gaussian distribution (38.2 ± 14.9 mmHg). Breathing 10% O 2 or carbogen resulted in dramatic changes in normal tissue oxygenation. Tumors growing intradermally in the back of air-breathing mice were extremely hypoxic and resistant to expected changes in oxygenation (carbogen breathing, size, and use of anesthetics). Tumors growing s.c. in the foot showed higher oxygen profiles with marked changes in oxygenation when exposing the animals to different levels of oxygen. However, the oxygenation of the mouse tumors transplanted in either site was only a fraction of that of the majority of human tumors. Conclusion: Experimental mouse tumors are markedly hypoxic, with median values of 10-20% of those of human tumors. Hence, mouse tumors are probably good models for the most hypoxic human tumors that respond poorly to radiotherapy; however, caution has to be exercised in extrapolating data from mouse to man

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

    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

  19. Effect of body position and oxygen tension on foramen ovale recruitment.

    Moses, Kayla L; Beshish, Arij G; Heinowski, Nicole; Baker, Kim R; Pegelow, David F; Eldridge, Marlowe W; Bates, Melissa L

    2015-01-01

    While there is an increased prevalence of stroke at altitude in individuals who are considered to be low risk for thrombotic events, it is uncertain how venous thrombi reach the brain. The patent foramen ovale (PFO) is a recruitable intracardiac shunt between the right and left atrium. We aimed to determine whether body position and oxygen tension affect blood flow through the PFO in healthy adults. We hypothesized that hypoxia and body positions that promote right atrial filling would independently recruit the PFO. Subjects with a PFO (n = 11) performed 11 trials, combining four different fractions of inhaled oxygen (FiO₂) (1.0, 0.21, 0.15, and 0.10) and three positions (upright, supine, and 45° head down), with the exception of FiO₂ = 0.10, while 45° head down. After 5 min in each position, breathing the prescribed oxygen tension, saline bubbles were injected into an antecubital vein and a four-chamber echocardiogram was obtained to evaluate PFO recruitment. We observed a high incidence of PFO recruitment in all conditions, with increased recruitment in response to severe hypoxia and some contribution of body position at moderate levels of hypoxia. We suspect that increased pulmonary vascular pressure, secondary to hypoxia-induced pulmonary vasoconstriction, increased right atrial pressure enough to recruit the PFO. Additionally, we hypothesize that the minor increase in breathing resistance that was added by the mouthpiece, used during experimental trials, affected intrathoracic pressure and venous return sufficiently to recruit the PFO. Copyright © 2015 the American Physiological Society.

  20. A Method for Combined Retinal Vascular and Tissue Oxygen Tension Imaging.

    Felder, Anthony E; Wanek, Justin; Tan, Michael R; Blair, Norman P; Shahidi, Mahnaz

    2017-09-06

    The retina requires adequate oxygenation to maintain cellular metabolism and visual function. Inner retinal oxygen metabolism is directly related to retinal vascular oxygen tension (PO 2 ) and inner retinal oxygen extraction fraction (OEF), whereas outer retinal oxygen consumption (QO 2 ) relies on oxygen availability by the choroid and is contingent upon retinal tissue oxygen tension (tPO 2 ) gradients across the retinal depth. Thus far, these oxygenation and metabolic parameters have been measured independently by different techniques in separate animals, precluding a comprehensive and correlative assessment of retinal oxygenation and metabolism dynamics. The purpose of the current study is to report an innovative optical system for dual oxyphor phosphorescence lifetime imaging to near-simultaneously measure retinal vascular PO 2 and tPO 2 in rats. The use of a new oxyphor with different spectral characteristics allowed differentiation of phosphorescence signals from the retinal vasculature and tissue. Concurrent measurements of retinal arterial and venous PO 2 , tPO 2 through the retinal depth, inner retinal OEF, and outer retinal QO 2 were demonstrated, permitting a correlative assessment of retinal oxygenation and metabolism. Future application of this method can be used to investigate the relations among retinal oxygen content, extraction and metabolism under pathologic conditions and thus advance knowledge of retinal hypoxia pathophysiology.

  1. The relationship between alveolar oxygen tension and the single-breath carbon monoxide diffusing capacity.

    Kanner, R E; Crapo, R O

    1986-04-01

    The effects of alveolar oxygen tension (PAO2) on the single-breath carbon monoxide diffusing capacity (DLCO) were quantified and a factor was derived to accommodate for differences in PAO2 over commonly encountered altitudes and/or varying concentrations of oxygen in the test gas mixture (FIO2) We performed duplicate measurements of DLCO in 7 normal subjects with 6 different oxygen fractions (0.176, 0.196, 0.211, 0.22, 0.25, and 0.27). The PAO2 for each test was measured as the PO2 in the alveolar gas sample bag. DLCO varied inversely with PAO2 and changed by 0.35% for each mmHg change in PAO2 (r = -0.62, p less than 0.001). At an FIO2 of 0.25, PAO2 varied between subjects and was highly correlated with each subject's residual volume to total lung capacity ratio (r = -0.84, p less than 0.001). We suggest that laboratories can adjust the measured DLCO when PAO2 is not congruent to 120 mmHg by the following formula: DLCO (corrected = DLCO (measured) x [1.0 + 0.0035 (PAO2 - 120)].

  2. Indomethacin decreases optic nerve oxygen tension by a mechanism other than cyclo-oxygenase inhibition

    Noergaard, M Hove; Pedersen, D Bach; Bang, K

    2008-01-01

    We investigated the effect of several Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), on the preoptic nerve oxygen tension (ONPO2), as indomethacin previously has demonstrated a strong decreasing effect on ONPO2. We tested whether these NSAIDs, like indomethacin, also reduce the increasing effect...

  3. Methyl sterol and cyclopropane fatty acid composition of Methylococcus capsulatus grown at low oxygen tensions

    Jahnke, L. L.; Nichols, P. D.

    1986-01-01

    The sterol and fatty acid concentrations for M. capsulatus grown in fed-batch cultures over a wide range of oxygen tensions (0.1-10.6 percent) and at a constant methane level are evaluated. The analyses reveal that the biomass decreases as oxygen levels are lowered; the sterol concentration increases when the oxygen range is between 0.5-1.1 percent and decreases when the oxygen range is below 0.5 percent; and the amount of monounsaturated C16 decreases and the concentration of cyclopropane fatty acids increases after oxygen is reduced. It is noted that growth and membrane synthesis occur at low oxygen concentrations and that the synthesis of membrane lipids responds to growth conditions.

  4. Control of oxygen tension recapitulates zone-specific functions in human liver microphysiology systems.

    Lee-Montiel, Felipe T; George, Subin M; Gough, Albert H; Sharma, Anup D; Wu, Juanfang; DeBiasio, Richard; Vernetti, Lawrence A; Taylor, D Lansing

    2017-10-01

    This article describes our next generation human Liver Acinus MicroPhysiology System (LAMPS). The key demonstration of this study was that Zone 1 and Zone 3 microenvironments can be established by controlling the oxygen tension in individual devices over the range of ca. 3 to 13%. The oxygen tension was computationally modeled using input on the microfluidic device dimensions, numbers of cells, oxygen consumption rates of hepatocytes, the diffusion coefficients of oxygen in different materials and the flow rate of media in the MicroPhysiology System (MPS). In addition, the oxygen tension was measured using a ratiometric imaging method with the oxygen sensitive dye, Tris(2,2'-bipyridyl) dichlororuthenium(II) hexahydrate (RTDP) and the oxygen insensitive dye, Alexa 488. The Zone 1 biased functions of oxidative phosphorylation, albumin and urea secretion and Zone 3 biased functions of glycolysis, α1AT secretion, Cyp2E1 expression and acetaminophen toxicity were demonstrated in the respective Zone 1 and Zone 3 MicroPhysiology System. Further improvements in the Liver Acinus MicroPhysiology System included improved performance of selected nonparenchymal cells, the inclusion of a porcine liver extracellular matrix to model the Space of Disse, as well as an improved media to support both hepatocytes and non-parenchymal cells. In its current form, the Liver Acinus MicroPhysiology System is most amenable to low to medium throughput, acute through chronic studies, including liver disease models, prioritizing compounds for preclinical studies, optimizing chemistry in structure activity relationship (SAR) projects, as well as in rising dose studies for initial dose ranging. Impact statement Oxygen zonation is a critical aspect of liver functions. A human microphysiology system is needed to investigate the impact of zonation on a wide range of liver functions that can be experimentally manipulated. Because oxygen zonation has such diverse physiological effects in the liver, we

  5. High Selectivity Oxygen Delignification

    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

  6. Multiple oxygen tension environments reveal diverse patterns of transcriptional regulation in primary astrocytes.

    Wayne Chadwick

    Full Text Available The central nervous system normally functions at O(2 levels which would be regarded as hypoxic by most other tissues. However, most in vitro studies of neurons and astrocytes are conducted under hyperoxic conditions without consideration of O(2-dependent cellular adaptation. We analyzed the reactivity of astrocytes to 1, 4 and 9% O(2 tensions compared to the cell culture standard of 20% O(2, to investigate their ability to sense and translate this O(2 information to transcriptional activity. Variance of ambient O(2 tension for rat astrocytes resulted in profound changes in ribosomal activity, cytoskeletal and energy-regulatory mechanisms and cytokine-related signaling. Clustering of transcriptional regulation patterns revealed four distinct response pattern groups that directionally pivoted around the 4% O(2 tension, or demonstrated coherent ascending/decreasing gene expression patterns in response to diverse oxygen tensions. Immune response and cell cycle/cancer-related signaling pathway transcriptomic subsets were significantly activated with increasing hypoxia, whilst hemostatic and cardiovascular signaling mechanisms were attenuated with increasing hypoxia. Our data indicate that variant O(2 tensions induce specific and physiologically-focused transcript regulation patterns that may underpin important physiological mechanisms that connect higher neurological activity to astrocytic function and ambient oxygen environments. These strongly defined patterns demonstrate a strong bias for physiological transcript programs to pivot around the 4% O(2 tension, while uni-modal programs that do not, appear more related to pathological actions. The functional interaction of these transcriptional 'programs' may serve to regulate the dynamic vascular responsivity of the central nervous system during periods of stress or heightened activity.

  7. BIOELECTRIC POTENTIALS IN HALICYSTIS : VII. THE EFFECTS OF LOW OXYGEN TENSION.

    Blinks, L R; Darsie, M L; Skow, R K

    1938-11-20

    The potential difference across the protoplasm of impaled cells of Halicystis is not affected by increase of oxygen tension in equilibrium with the sea water, nor with decrease down to about 1/10 its tension in the air (2 per cent O(2) in N(2)). When bubbling of 2 per cent O(2) is stopped, the P.D. drifts downward, to be restored on stirring the sea water, or rebubbling the gas. Bubbling 0.2 per cent O(2) causes the P.D. to drop to 20 mv. or less; 1.1 per cent O(2) to about 50 mv. Restoration of 2 per cent or higher O(2) causes recovery to 70 or 80 mv. often with a preliminary cusp which decreases the P.D. before it rises. Perfusion of aerated sea water through the vacuole is just as effective in restoring the P.D. as external aeration, indicating that the direction of the oxygen gradient is not significant. Low O(2) tension also inhibits the reversed, negative P.D. produced by adding NH(4)Cl to sea water, 0.2 per cent O(2) bringing this P.D. back to the same low positive values found without ammonia. Restoration of 2 per cent O(2) or air, restores this latent negativity. At slightly below the threshold for ammonia reversal, low O(2) may induce a temporary negativity when first bubbled, and a negative cusp may occur on aeration before positive P.D. is regained. This may be due to a decreased consumption of ammonia, or to intermediate pH changes. The locus of the P.D. alteration was tested by applying increased KCl concentrations to the cell exterior; the large cusps produced in aerated solutions become greatly decreased when the P.D. has fallen in 0.2 per cent O(2). This indicates that the originally high relative mobility or concentration of K(+) ion has approached that of Na(+) in the external protoplasmic surface under reduced O(2) tension. Results obtained with sulfate sea water indicate that Na(+) mobility approaches that of SO(4) (-) in 0.2 per cent O(2). P.D. measurements alone cannot tell whether this is due to an increase of the slower ion or a decrease of

  8. Study on the makinq of Cockroft Walton high tension

    Hutapea, Sumihar.

    1976-01-01

    A prototype of a generator is being developed at the GAMA Research Center. Experience in working with some components, high voltage capacitor, column, and potential divider is discussed. High voltage diode, the type which is usually used in television, is used. The tension of the generator is measured by using the high ohmic resistence of 4000 megaohm. The maximum tension can be reached no more than 150000 volts. (author)

  9. The Role of Oxygen Tension in Penile Erection and Its Relationship to Erectile Dysfunction

    Jong-Kwan Park

    2004-01-01

    Full Text Available The corpus cavernosum of the penis is one of the few vascular beds in which there is a change in oxygen tension with function (blood PO2 25-40mm Hg in the flaccid state, and 90-100mm Hg in the erect state. This change in oxygen tension exposes the components of the corpus cavernosum to a variety of cytokines, humoral, vasoactive, and growth factors which may affect the structure and function of the endothelial cells, smooth muscle cells, neurons and extracellular matrix. Among these cell types, endothelial cells are the first line of defense to blood-borne stress and can affect the underlying smooth muscle via paracrine mechanisms. Impotence is defined as the inability to obtain or sustain an erection sufficient for vaginal penetration and can result from a variety of pathological conditions, vascular disease, endocrine disease, neurological disease, and psychogenic disorders. The penis is a vascular organ and as such is susceptible to the effects of vascular diseases. This review will discuss the basic etiology of erection and vasculogenic erectile dysfunction and explore the role oxygen tension in regulating various cellular and humoral factors as well as trabecular structure and function.

  10. [Effect of different oxygen tension on the cytoskeleton remodeling of goat temporomandibular joint disc cells].

    Xiaolan, He; Guangjie, Bao; Linglu, Sun; Xue, Zhang; Shanying, Bao; Hong, Kang

    2017-08-01

    Objective The effect of different oxygen tensions on the cytoskeleton remodeling of goat temporomandibular joint (TMJ) disc cells were investigated. Methods Goat TMJ disc cells were cultured under normoxia (21% O₂) and hypoxia (2%, 4%, and 8% O₂). Toluidine blue, picrosirius red, and type Ⅰ collagen immunocytochemical staining were performed to observe the changes in cell phenotype under different oxygen levels. Immunofluorescent staining and real-time reverse transcription-polymerase chain reaction analysis were then performed to identify actin, tubulin, and vimentin in the cultured disc cells. Results TMJ disc cells still displayed fibroblast characteristics under different oxygen levels and their cytoskeletons had regular arrangement. The fluorescence intensities of actin and vimentin were lowest at 4% O₂(P0.05). Actin mRNA levels were considerably decreased at 2% O₂ and 4% O₂ in hypoxic conditions, while actin mRNA expression was highest in 21% O₂. Tubulin mRNA levels considerably increased at 2% O₂, while tubulin mRNA expression was lowest in 8% O₂ (Plevels among these oxygen levels (Poxygen tensions, and 2% O₂ may be the optimal oxygen level required to proliferate TMJ disc cells.

  11. [Long-term expansion of multipotent mesenchymal stromal cells under reduced oxygen tension].

    Rylova, Iu V; Buravkova, L B

    2013-01-01

    We have shown that the decrease in oxygen tension in the culture medium of multipotent mesenchymal stromal cells (MMSCs) results in a short-term reduction in the proportion of CD73(+)-cells in the population, without effecting the number of cells expressing other constitutive surface markers (CD90 and CD105). In this case, the heterogeneity of the cell population declined: large spread cells disappeared. The proliferative activity of MMSCs significantly increased and remained stable in conditions in which the oxygen content was close to the tissue oxygen levels (5% O2). At lower oxygen concentration, proliferative activity of the cells gradually reduced from passages 3-4. The increase in proliferative activity was not accompanied by increased expression of telomerase gene indicateding the alsance of cell transformation. However, genome-wide analysis of MMSC gene expression level revealed changes in expression of cyclins (CCND2 and PCNA), regulatory subunit cyclin-dependent kinase (CKS2) and an inhibitor of cyclin-dependent kinase (CDKN2C), regulating the cell cycle, which is obviously facilitated the increase in the proliferative capacity of cells at lower oxygen tension.

  12. Oxidative stress under ambient and physiological oxygen tension in tissue culture

    Jagannathan, Lakshmanan; Cuddapah, Suresh; Costa, Max

    2016-01-01

    Oxygen (O2) levels range from 2–9% in vivo. However, cell culture experiments are performed at atmospheric O2 levels (21%). Oxidative stress due to generation of reactive oxygen species (ROS) in cells cultured at higher than physiological levels is implicated in multitude of deleterious effects including DNA damage, genomic instability and senescence. In addition, oxidative stress activates redox sensitive transcription factors related to inflammatory signaling and apoptotic signaling. Furthermore, several chromatin-modifying enzymes are affected by ROS, potentially impacting epigenetic regulation of gene expression. While primary cells are cultured at lower O2 levels due to their inability to grow at higher O2, the immortalized cells, which display no such apparent growth difficulties, are typically cultured at 21% O2. This review will provide an overview of issues associated with increased oxygen levels in in vitro cell culture and point out the benefits of using lower levels of oxygen tension even for immortalized cells. PMID:27034917

  13. Microcomputer-based system for registration of oxygen tension in peripheral muscle.

    Odman, S; Bratt, H; Erlandsson, I; Sjögren, L

    1986-01-01

    For registration of oxygen tension fields in peripheral muscle a microcomputer based system was designed on the M6800 microprocessor. The system was designed to record the signals from a multiwire oxygen electrode, MDO, which is a multiwire electrode for measuring oxygen on the surface of an organ. The system contained patient safety isolation unit built on optocopplers and the upper frequency limit was 0.64 Hz. Collected data were corrected for drift and temperature changes during the measurement by using pre- and after calibrations and a linear compensation technique. Measure drift of the electrodes were proved to be linear and thus the drift could be compensated for. The system was tested in an experiment on pig. To study the distribution of oxygen statistically mean, standard deviation, skewness and curtosis were calculated. To see changes or differences between histograms a Kolmogorv-Smirnov test was used.

  14. Effect of epidural blockade and oxygen therapy on changes in subcutaneous oxygen tension after abdominal surgery

    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....

  15. Oxygen tension regulates the osteogenic, chondrogenic and endochondral phenotype of bone marrow derived mesenchymal stem cells

    Sheehy, Eamon J.; Buckley, Conor T. [Trinity Centre for Bioengineering, School of Engineering, Trinity College Dublin, Dublin 2 (Ireland); Kelly, Daniel J., E-mail: kellyd9@tcd.ie [Trinity Centre for Bioengineering, School of Engineering, Trinity College Dublin, Dublin 2 (Ireland)

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Expansion in low oxygen enhances MSC proliferation and osteogenesis. Black-Right-Pointing-Pointer Differentiation in low oxygen enhances chondrogenesis and suppresses hypertrophy. Black-Right-Pointing-Pointer Oxygen can regulate the MSC phenotype for use in tissue engineering applications. -- Abstract: The local oxygen tension is a key regulator of the fate of mesenchymal stem cells (MSCs). The objective of this study was to investigate the effect of a low oxygen tension during expansion and differentiation on the proliferation kinetics as well as the subsequent osteogenic and chondrogenic potential of MSCs. We first hypothesised that expansion in a low oxygen tension (5% pO{sub 2}) would improve both the subsequent osteogenic and chondrogenic potential of MSCs compared to expansion in a normoxic environment (20% pO{sub 2}). Furthermore, we hypothesised that chondrogenic differentiation in a low oxygen environment would suppress hypertrophy of MSCs cultured in both pellets and hydrogels used in tissue engineering strategies. MSCs expanded at 5% pO{sub 2} proliferated faster forming larger colonies, resulting in higher cell yields. Expansion at 5% pO{sub 2} also enhanced subsequent osteogenesis of MSCs, whereas differentiation at 5% pO{sub 2} was found to be a more potent promoter of chondrogenesis than expansion at 5% pO{sub 2}. Greater collagen accumulation, and more intense staining for collagen types I and X, was observed in pellets maintained at 20% pO{sub 2} compared to 5% pO{sub 2}. Both pellets and hydrogels stained more intensely for type II collagen when undergoing chondrogenesis in a low oxygen environment. Differentiation at 5% pO{sub 2} also appeared to inhibit hypertrophy in both pellets and hydrogels, as demonstrated by reduced collagen type X and Alizarin Red staining and alkaline phosphatase activity. This study demonstrates that the local oxygen environment can be manipulated in vitro to either stabilise a

  16. Low Oxygen Tension Enhances Expression of Myogenic Genes When Human Myoblasts Are Activated from G0 Arrest

    Sellathurai, Jeeva; Nielsen, Joachim; Hejbøl, Eva Kildall

    2016-01-01

    -PCR, immunocytochemistry and western blot. RESULTS AND CONCLUSIONS: We found an increase in proliferation rate of myoblasts when activated at a low oxygen tension (1% O2) compared to 21% O2. In addition, the gene expression studies showed up regulation of the myogenesis related genes PAX3, PAX7, MYOD, MYOG (myogenin), MET......, NCAM, DES (desmin), MEF2A, MEF2C and CDH15 (M-cadherin), however, the fraction of DES and MYOD positive cells was not increased by low oxygen tension, indicating that 1% O2 may not have a functional effect on the myogenic response. Furthermore, the expression of genes involved in the TGFβ, Notch...... and Wnt signaling pathways were also up regulated in low oxygen tension. The differences in gene expression were most pronounced at day one after activation from G0-arrest, thus the initial activation of myoblasts seemed most sensitive to changes in oxygen tension. Protein expression of HES1 and β...

  17. Impact of low oxygen tension on stemness, proliferation and differentiation potential of human adipose-derived stem cells

    Choi, Jane Ru; Pingguan-Murphy, Belinda; Wan Abas, Wan Abu Bakar [Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Lembah Pantai, 50603 Kuala Lumpur (Malaysia); Noor Azmi, Mat Adenan; Omar, Siti Zawiah [Department of Obstetrics and Gynaecology, Faculty of Medicine, University of Malaya, Lembah Pantai, 50603 Kuala Lumpur (Malaysia); Chua, Kien Hui [Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur (Malaysia); Wan Safwani, Wan Kamarul Zaman, E-mail: wansafwani@um.edu.my [Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Lembah Pantai, 50603 Kuala Lumpur (Malaysia)

    2014-05-30

    Highlights: • Hypoxia maintains the stemness of adipose-derived stem cells (ASCs). • ASCs show an increased proliferation rate under low oxygen tension. • Oxygen level as low as 2% enhances the chondrogenic differentiation potential of ASCs. • HIF-1α may regulate the proliferation and differentiation activities of ASCs under hypoxia. - Abstract: Adipose-derived stem cells (ASCs) have been found adapted to a specific niche with low oxygen tension (hypoxia) in the body. As an important component of this niche, oxygen tension has been known to play a critical role in the maintenance of stem cell characteristics. However, the effect of O{sub 2} tension on their functional properties has not been well determined. In this study, we investigated the effects of O{sub 2} tension on ASCs stemness, differentiation and proliferation ability. Human ASCs were cultured under normoxia (21% O{sub 2}) and hypoxia (2% O{sub 2}). We found that hypoxia increased ASC stemness marker expression and proliferation rate without altering their morphology and surface markers. Low oxygen tension further enhances the chondrogenic differentiation ability, but reduces both adipogenic and osteogenic differentiation potential. These results might be correlated with the increased expression of HIF-1α under hypoxia. Taken together, we suggest that growing ASCs under 2% O{sub 2} tension may be important in expanding ASCs effectively while maintaining their functional properties for clinical therapy, particularly for the treatment of cartilage defects.

  18. High Selectivity Oxygen Delignification

    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.

  19. Indomethacin lowers optic nerve oxygen tension and reduces the effect of carbonic anhydrase inhibition and carbon dioxide breathing

    Pedersen, D B; Eysteinsson, T; Stefánsson, E

    2004-01-01

    Prostaglandins are important in blood flow regulation. Carbon dioxide (CO(2)) breathing and carbonic anhydrase inhibition increase the oxygen tension in the retina and optic nerve. To study the mechanism of this effect and the role of cyclo-oxygenase in the regulation of optic nerve oxygen tension...... (ONPO(2)), the authors investigated how indomethacin affects ONPO(2) and the ONPO(2) increases caused by CO(2) breathing and carbonic anhydrase inhibition in the pig....

  20. The role of tissue oxygen tension in the control of local blood flow in the microcirculation of skeletal muscles

    Ngo, Thuc Anh

    2010-01-01

    In the microcirculation blood flow is highly regulated dependent on the metabolic activity of the tissues. Among several mechanisms, mechanisms involved in the coupling of changes in tissue oxygen tension due to changes in the metabolic activity of the tissue play an important role. In the systemic...... (inhibitor of KATP channels) in the superfusate abolished both vasodilatation and constriction to low and high oxygen superfusate, indicating that KATP channels are involved in both hypoxic vasodilatation and hyperoxic vasoconstriction. Red blood cells (RBCs) have been proposed to release ATP and...... as in the intact blood-perfused arteriole. This indicates that RBCs are not essential for hypoxic vasodilatation. In addition several potential pathways were evaluated. Application of DPCPX (inhibitor of adenosine A1 and A2 receptors) and L-NAME (inhibitor of NO-synthase) did not affect vasomotor responses to low...

  1. Cerebral interstitial tissue oxygen tension, pH, HCO3, CO2.

    Charbel, F T; Hoffman, W E; Misra, M; Hannigan, K; Ausman, J I

    1997-10-01

    There are many techniques for monitoring the injured brain following trauma, subarachnoid hemorrhage, or surgery. It is thought that the major determinants for recovery of injured cerebral tissue are oxygen, glucose delivery, and the clearance of metabolites. These factors, at optimal levels, are probably responsible for the regaining of neuronal functions. These parameters are in turn dependent on the tissue's blood flow and metabolism. We have been using a single, compact, polyethylene sensor, the Paratrend 7 for the measurement of cerebral oxygen tension, CO2, pH, and temperature. This sensor is designed for continuous blood gas analysis to aid in monitoring neurosurgical patients, both during surgery and in the intensive care unit. Using the Paratrend 7 sensor, we found the normal range of values to be: PO2 33 +/- 11 mm Hg; PCO2 48 +/- 7 mm Hg; pH 7.19 +/- 0.11. Critical measurements are considered to be tissue PO2 60 mm Hg, and pH effective method of measuring tissue cerebral oxygen tension, along with carbon dioxide levels, pH, and temperature.

  2. Oxygen tension and prediction of the radiation response. Polarographic study in human breast cancer

    Pappova, N.; Siracka, E.

    1982-01-01

    Serial polarographic measurement of the tissue oxygen tension (pO 2 ) was made in the course of fractionated irradiation (preoperative or sole treatment) of advanced breast cancer in 24 patients. In responsive tumors an increase in pO 2 appeared sooner before expressive tumor size reduction became noticeable. Repeated recording of unchanged pO 2 values proved to be a good prognostic indicator of local failure. The study made on this tumor model showed that serial polarographic pO 2 determinations with suitable electrodes causing minimal trauma and providing consistent and reproductive data about changes in tumor microcirculation and oxygenation may enlarge the scale of indicators of radiation response. (author)

  3. Evaluation of multi-exponential curve fitting analysis of oxygen-quenched phosphorescence decay traces for recovering microvascular oxygen tension histograms

    Bezemer, Rick; Faber, Dirk J.; Almac, Emre; Kalkman, Jeroen; Legrand, Matthieu; Heger, Michal; Ince, Can

    2010-01-01

    Although it is generally accepted that oxygen-quenched phosphorescence decay traces can be analyzed using the exponential series method (ESM), its application until now has been limited to a few (patho)physiological studies, probably because the reliability of the recovered oxygen tension (pO(2))

  4. Effect of supplemental oxygen versus dobutamine administration on liver oxygen tension in dPP-guided normovolemic pigs.

    Pestel, G; Fukui, K; Hager, H; Kurz, A; Hiltebrand, L

    2009-01-01

    Difference in pulse pressure (dPP) confirms adequate intravascular filling as a prerequisite for tissue perfusion. We hypothesized that both oxygen and dobutamine increase liver tissue oxygen tension (ptO(2)). Eight anesthetized pigs received dPP-guided fluid management. Hepatic pO(2) was measured with Clark-type electrodes placed subcapsularly, and on the liver surface. Pigs received: (1) supplemental oxygen (F(i)O(2) 1.0); (2) dobutamine 2.5 microg/kg/min, and (3) dobutamine 5 microg/kg/min. Data were analyzed using repeated-measures ANOVA followed by a Tukey post-test for multiple comparisons. ptO(2 )measured subcapsularly and at the liver surface were compared using the Bland-Altman plot. Variation in F(i)O(2) changed local hepatic tissue ptO(2) [subcapsular measurement: 39 +/- 12 (F(i)O(2) 0.3), 89 +/- 35 mm Hg (F(i)O(2) 1.0, p = 0.01 vs. F(i)O(2) 0.3), 44 +/- 10 mm Hg (F(i)O(2) 0.3, p = 0.05 vs. F(i)O(2) 1.0); surface measurement: 52 +/- 35 (F(i)O(2) 0.3), 112 +/- 24 mm Hg (F(i)O(2) 1.0, p = 0.001 vs. F(i)O(2) 0.3), 54 +/- 24 mm Hg (F(i)O(2) 0.3, p = 0.001 vs. F(i)O(2) 1.0)]. Surface measurements were widely scattered compared to subcapsular measurements (bias: -15 mm Hg, precision: 76.3 mm Hg). Dobutamine did not affect hepatic oxygenation. Supplemental oxygen increased hepatic tissue pO(2) while dobutamine did not. Although less invasive, the use of surface measurements is discouraged. Copyright 2009 S. Karger AG, Basel.

  5. Electrical injuries due to railway high tension cables.

    Reichl, M; Kay, S

    1985-08-01

    We have noted a large number of young boys being admitted to our Unit with burns due to railway high tension cables. On review of these cases we have noted: most of the burns were due to arcing, there is a high level of ignorance among the population at risk. We propose some ways of preventing these injuries.

  6. Enhanced dopaminergic differentiation of human neural stem cells by synergistic effect of Bcl-xL and reduced oxygen tension

    Krabbe, Christina; Courtois, Elise; Jensen, Pia

    2009-01-01

    Neural stem cells constitute a promising source of cells for transplantation in Parkinson's disease, but a protocol for controlled dopaminergic differentiation is not yet available. Here we investigated the effect of the anti-apoptotic protein Bcl-x(L) and oxygen tension on dopaminergic different......Neural stem cells constitute a promising source of cells for transplantation in Parkinson's disease, but a protocol for controlled dopaminergic differentiation is not yet available. Here we investigated the effect of the anti-apoptotic protein Bcl-x(L) and oxygen tension on dopaminergic...... days at 20% oxygen, hVMbcl-x(L) cultures contained proportionally more tyrosine hydroxylase(TH)-positive cells than hVM1 control cultures. This difference was significantly potentiated from 11 +/- 0.8% to 17.2 +/- 0.2% of total cells when the oxygen tension was lowered to 3%. Immunocytochemistry and Q...

  7. Reactive oxygen species-driven HIF1α triggers accelerated glycolysis in endothelial cells exposed to low oxygen tension

    Paik, Jin-Young; Jung, Kyung-Ho; Lee, Jin-Hee; Park, Jin-Won; Lee, Kyung-Han

    2017-01-01

    Endothelial cells and their metabolic state regulate glucose transport into underlying tissues. Here, we show that low oxygen tension stimulates human umbilical vein endothelial cell 18 F–fluorodeoxyglucose ( 18 F–FDG) uptake and lactate production. This was accompanied by augmented hexokinase activity and membrane Glut-1, and increased accumulation of hypoxia-inducible factor-1α (HIF1α). Restoration of oxygen reversed the metabolic effect, but this was blocked by HIF1α stabilization. Hypoxia-stimulated 18 F–FDG uptake was completely abrogated by silencing of HIF1α expression or by a specific inhibitor. There was a rapid and marked increase of reactive oxygen species (ROS) by hypoxia, and ROS scavenging or NADPH oxidase inhibition completely abolished hypoxia-stimulated HIF1α and 18 F–FDG accumulation, placing ROS production upstream of HIF1α signaling. Hypoxia-stimulated HIF1α and 18 F–FDG accumulation was blocked by the protein kinase C (PKC) inhibitor, staurosporine. The phosphatidylinositol 3-kinase (PI3K) inhibitor, wortmannin, blocked hypoxia-stimulated 18 F–FDG uptake and attenuated hypoxia-responsive element binding of HIF1α without influencing its accumulation. Thus, ROS-driven HIF1α accumulation, along with PKC and PI3K signaling, play a key role in triggering accelerated glycolysis in endothelial cells under hypoxia, thereby contributing to 18 F–FDG transport.

  8. High tension generator for corona barrier discharge

    Baltag, O.; Costandache, D.; Gheorghiu, M.; Paraschivescu, A.; Popa, G.

    2001-01-01

    Different types of high-voltage generators are in use for the study of low pressure (or atmospheric) discharges. Mostly used are the Tesla coils generators or the power generators working in linear or switching regime. The Tesla coils generators have the advantage of a simple bloc diagram. In exchange, they have a number of short-comings, such as: the difficulty in modifying the frequency of the high voltage pulses, generation of a high voltage and frequency pulse train, the amplitude is not constant.This paper presents a high-voltage generator meant to be used in the study of the dielectric barrier discharges (DBD). The bloc diagram is presented. Performances obtained are as follows: - Generated frequency: 10 Hz - 100 Hz, 100 Hz - 1 KHz, 1 KHz - 10 KHz; - High voltage pulses control: a single pulse from an internal or external generator; - Synchronization with the oscilloscope, variable delay: 5 μs - 0.1 s; - Output voltage: variable both smoothly and in steps: 1 kV -15 kV; - High voltage polarity: mono and bipolar; - Output power during the continuous duty: 300 VA (maximum 600 VA for a short time); - Pulse energy: 0.23 J; - Pulse duration: 4 μs - 50 μs

  9. Towards a quantitative understanding of oxygen tension and cell density evolution in fibrin hydrogels.

    Demol, Jan; Lambrechts, Dennis; Geris, Liesbet; Schrooten, Jan; Van Oosterwyck, Hans

    2011-01-01

    The in vitro culture of hydrogel-based constructs above a critical size is accompanied by problems of unequal cell distribution when diffusion is the primary mode of oxygen transfer. In this study, an experimentally-informed mathematical model was developed to relate cell proliferation and death inside fibrin hydrogels to the local oxygen tension in a quantitative manner. The predictive capacity of the resulting model was tested by comparing its outcomes to the density, distribution and viability of human periosteum derived cells (hPDCs) that were cultured inside fibrin hydrogels in vitro. The model was able to reproduce important experimental findings, such as the formation of a multilayered cell sheet at the hydrogel periphery and the occurrence of a cell density gradient throughout the hydrogel. In addition, the model demonstrated that cell culture in fibrin hydrogels can lead to complete anoxia in the centre of the hydrogel for realistic values of oxygen diffusion and consumption. A sensitivity analysis also identified these two parameters, together with the proliferation parameters of the encapsulated cells, as the governing parameters for the occurrence of anoxia. In conclusion, this study indicates that mathematical models can help to better understand oxygen transport limitations and its influence on cell behaviour during the in vitro culture of cell-seeded hydrogels. Copyright © 2010 Elsevier Ltd. All rights reserved.

  10. Oxygen tension is a determinant of the matrix-forming phenotype of cultured human meniscal fibrochondrocytes.

    Adetola B Adesida

    Full Text Available BACKGROUND: Meniscal cartilage displays a poor repair capacity, especially when injury is located in the avascular region of the tissue. Cell-based tissue engineering strategies to generate functional meniscus substitutes is a promising approach to treat meniscus injuries. Meniscus fibrochondrocytes (MFC can be used in this approach. However, MFC are unable to retain their phenotype when expanded in culture. In this study, we explored the effect of oxygen tension on MFC expansion and on their matrix-forming phenotype. METHODOLOGY/PRINCIPAL FINDINGS: MFC were isolated from human menisci followed by basic fibroblast growth factor (FGF-2 mediated cell expansion in monolayer culture under normoxia (21%O(2 or hypoxia (3%O(2. Normoxia and hypoxia expanded MFC were seeded on to a collagen scaffold. The MFC seeded scaffolds (constructs were cultured in a serum free chondrogenic medium for 3 weeks under normoxia and hypoxia. Constructs containing normoxia-expanded MFC were subsequently cultured under normoxia while those formed from hypoxia-expanded MFC were subsequently cultured under hypoxia. After 3 weeks of in vitro culture, the constructs were assessed biochemically, histologically and for gene expression via real-time reverse transcription-PCR assays. The results showed that constructs under normoxia produced a matrix with enhanced mRNA ratio (3.5-fold higher; p<0.001 of collagen type II to I. This was confirmed by enhanced deposition of collagen II using immuno-histochemistry. Furthermore, the constructs under hypoxia produced a matrix with higher mRNA ratio of aggrecan to versican (3.5-fold, p<0.05. However, both constructs had the same capacity to produce a glycosaminoglycan (GAG -specific extracellular matrix. CONCLUSIONS: Our data provide evidence that oxygen tension is a key player in determining the matrix phenotype of cultured MFC. These findings suggest that the use of normal and low oxygen tension during MFC expansion and subsequent neo

  11. Differences of optic disc appearance between normal tension and high tension glaucoma patients

    Stojčić Milan

    2011-01-01

    Full Text Available Introduction. The term glaucoma is used to cover a wide range of diseases, whose main feature is optic neuropathy. According to the level of intraocular pressure (IOP, the open angle glaucoma is arbitrarily divided into high tension glaucoma (HTG and normal tension glaucoma (NTG. Objective. The aim of this study was to investigate the differences of optic disc cup appearance between patients with NTG and HTG. Methods. Prospective study included 30 patients (60 eyes with NTG and 30 patients (60 eyes with HTG. IOP was measured by Goldmann applanation tonometry. Examination of optic disc head was performed by indirect ophthalmoscopy with Volk 90 D superfield lens through a dilated pupil to observe qualitative and quantitative parameters. Visual fields were examined in all patients with the Octopus program G1, full threshold strategy (Octopus 500 EZ, Interzeag, Switzerland. Results. Vertical form of optic disc cup was present in 11 eyes with NTG (18.3% and three eyes with HTG (5% (p<0.05. A disc with localized tissue loss (polar notching on the inferior pole was observed in eight eyes with NTG (13.3% and in one eye with HTG (1.7% (p<0.01. Uniformly enlarged, round cup was more frequent in patients with HTG than NTG: 93.3% and 68.3% respectively (p<0.05. Conclusion. The perceived differences indicate a complex multifactorial nature of glaucoma disease and a possible existence of two pathophysiological ways of optic disc changes within the same basic disease.

  12. The effect of oxygen tension on porcine embryonic development is dependent on embryo type

    Booth, Paul; Holm, Peter; Callesen, Henrik

    2005-01-01

    of the embryos prior to culture--a study was performed to examine the effect of O2 tension during culture on three different types of porcine embryos, namely: in vivo flushed embryos, and in vitro matured oocytes either fertilized in vitro or parthenogenetically activated. In vivo embryos (n=208) were flushed...... supplemented with 10% calf serum until day 7. The gas environment for IVM/IVF was 5% CO2 in air, while that for IVC was either 5% CO2 in air or 5% O2, 5% CO2 and 90% N2. Low O2 tension increased both day 7 blastocyst rates (high versus low O2, respectively; 9.3+/-2.9%: 26/280; 23.9+/-4.2%: 71/293; P...

  13. Near-simultaneous hemoglobin saturation and oxygen tension maps in mouse brain using an AOTF microscope.

    Shonat, R D; Wachman, E S; Niu, W; Koretsky, A P; Farkas, D L

    1997-09-01

    A newly developed microscope using acousto-optic tunable filters (AOTFs) was used to generate in vivo hemoglobin saturation (SO2) and oxygen tension (PO2) maps in the cerebral cortex of mice. SO2 maps were generated from the spectral analysis of reflected absorbance images collected at different wavelengths, and PO2 maps were generated from the phosphorescence lifetimes of an injected palladium-porphyrin compound using a frequency-domain measurement. As the inspiratory O2 was stepped from hypoxia (10% O2), through normoxia (21% O2), to hyperoxia (60% O2), measured SO2 and PO2 levels rose accordingly and predictably throughout. A plot of SO2 versus PO2 in different arterial and venous regions of the pial vessels conformed to the sigmoidal shape of the oxygen-hemoglobin dissociation curve, providing further validation of the two mapping procedures. The study demonstrates the versatility of the AOTF microscope for in vivo physiologic investigation, allowing for the generation of nearly simultaneous SO2 and PO2 maps in the cerebral cortex, and the frequency-domain detection of phosphorescence lifetimes. This class of study opens up exciting new possibilities for investigating the dynamics of hemoglobin and O2 binding during functional activation of neuronal tissues.

  14. Effect of low oxygen tension on the biological characteristics of human bone marrow mesenchymal stem cells.

    Kim, Dae Seong; Ko, Young Jong; Lee, Myoung Woo; Park, Hyun Jin; Park, Yoo Jin; Kim, Dong-Ik; Sung, Ki Woong; Koo, Hong Hoe; Yoo, Keon Hee

    2016-11-01

    Culture of mesenchymal stem cells (MSCs) under ambient conditions does not replicate the low oxygen environment of normal physiological or pathological states and can result in cellular impairment during culture. To overcome these limitations, we explored the effect of hypoxia (1 % O 2 ) on the biological characteristics of MSCs over the course of different culture periods. The following biological characteristics were examined in human bone marrow-derived MSCs cultured under hypoxia for 8 weeks: proliferation rate, morphology, cell size, senescence, immunophenotypic characteristics, and the expression levels of stemness-associated factors and cytokine and chemokine genes. MSCs cultured under hypoxia for approximately 2 weeks showed increased proliferation and viability. During long-term culture, hypoxia delayed phenotypic changes in MSCs, such as increased cell volume, altered morphology, and the expression of senescence-associated-β-gal, without altering their characteristic immunophenotypic characteristics. Furthermore, hypoxia increased the expression of stemness and chemokine-related genes, including OCT4 and CXCR7, and did not decrease the expression of KLF4, C-MYC, CCL2, CXCL9, CXCL10, and CXCR4 compared with levels in cells cultured under normoxia. In conclusion, low oxygen tension improved the biological characteristics of MSCs during ex vivo expansion. These data suggest that hypoxic culture could be a useful method for increasing the efficacy of MSC cell therapies.

  15. [Extensive injuries due to high-tension electrical current].

    Tomásek, D; Königová, R; Snupárek, Z

    1989-03-01

    The authors submit a case of severe injury with high tension electric current. They emphasize the necessity of prevention of this injury which occurs most frequently when transformer stations are not adequately safeguarded, in case of inadequate protection when approaching trolley wires on the railway track, and when safety principles are not respected during work on the railway. The authors draw attention to the importance of immediate resuscitation and multidisciplinary comprehensive care.

  16. Exogenous and endogenous angiotensin-II decrease renal cortical oxygen tension in conscious rats by limiting renal blood flow

    Emans, Tonja W.; Janssen, Ben J.; Pinkham, Maximilian I.; Ow, Connie P. C.; Evans, Roger G.; Joles, Jaap A.; Malpas, Simon C.; Krediet, C. T. Paul; Koeners, Maarten P.

    2016-01-01

    Our understanding of the mechanisms underlying the role of hypoxia in the initiation and progression of renal disease remains rudimentary. We have developed a method that allows wireless measurement of renal tissue oxygen tension in unrestrained rats. This method provides stable and continuous

  17. Measuring oxygen tension modulation, induced by a new pre-radiotherapy therapeutic, in a mammary window chamber mouse model

    Schafer, Rachel; Gmitro, Arthur F.

    2015-03-01

    Tumor regions under hypoxic or low oxygen conditions respond less effectively to many treatment strategies, including radiation therapy. A novel investigational therapeutic, NVX-108 (NuvOx Pharma), has been developed to increase delivery of oxygen through the use of a nano-emulsion of dodecofluoropentane. By raising pO2 levels prior to delivering radiation, treatment efficacy may be improved. To aid in evaluating the novel drug, oxygen tension was quantitatively measured, spatially and temporally, to record the effect of administrating NVX-108 in an orthotopic mammary window chamber mouse model of breast cancer. The oxygen tension was measured through the use of an oxygen-sensitive coating, comprised of phosphorescent platinum porphyrin dye embedded in a polystyrene matrix. The coating, applied to the surface of the coverslip of the window chamber through spin coating, is placed in contact with the mammary fat pad to record the oxygenation status of the surface tissue layer. Prior to implantation of the window chamber, a tumor is grown in the SCID mouse model by injection of MCF-7 cells into the mammary fat pad. Two-dimensional spatial distributions of the pO2 levels were obtained through conversion of measured maps of phosphorescent lifetime. The resulting information on the spatial and temporal variation of the induced oxygen modulation could provide valuable insight into the optimal timing between administration of NVX-108 and radiation treatment to provide the most effective treatment outcome.

  18. Increase of tumor oxygen tension and potentiation of radiation effects using pentoxifylline, vinpocetine and ticlopidine hydrochloride

    Amano, Morikazu; Monzen, Hajime; Suzuki, Takatoshi; Hasegawa, Takeo

    2004-01-01

    The effects of pentoxifylline (PTX), vinpocetine (VPT) and ticlopidine hydrochloride (TCD), each drug commonly used for vascular disorders in humans, on the pO 2 in SCC-7 (squamous cell carcinoma) tumors of C3H/HeJ mice on the radioresponse of SCC-7 tumors were investigated. When the SCC-7 implanted in the leg of C3H/HeJ mice grew about 100 mm 3 , the effects of PTX, VPT and TCD on the increase oxygen tension in the tumor was determined with polarography. The mice were injected intraperitoneally (ip) with 5 ml/kg PTX, 5 ml/kg VPT, or 10 ml/kg TCD, the tumor pO 2 increased slowly, peaked about 20-50 min postinjection, and returned to its original level in 60-80 min. When the C3H/HeJ mice bearing SCC-7 tumors in the legs were injected ip with 5 ml/kg PTX, 5 ml/kg VPT or 10 ml/kg TCD and tumors were X-irradiated 30 min later, the radiation induced growth delay of the tumor was greater than that caused by X-irradiation alone. The results in the present study, PTX, VPT and TCD increase the tumor pO 2 in rodent tumors strongly suggest that each drug may be useful for increasing the radiosensitivity of human tumor. (author)

  19. Localized increase of tissue oxygen tension by magnetic targeted drug delivery

    Liong, Celine; Ortiz, Daniel; Ao-ieong, Eilleen; Navati, Mahantesh S.; Friedman, Joel M.; Cabrales, Pedro

    2014-07-01

    Hypoxia is the major hindrance to successful radiation therapy of tumors. Attempts to increase the oxygen (O2) tension (PO2) of tissue by delivering more O2 have been clinically disappointing, largely due to the way O2 is transported and released by the hemoglobin (Hb) within the red blood cells (RBCs). Systemic manipulation of O2 transport increases vascular resistance due to metabolic autoregulation of blood flow to prevent over oxygenation. This study investigates a new technology to increase O2 delivery to a target tissue by decreasing the Hb-O2 affinity of the blood circulating within the targeted tissue. As the Hb-O2 affinity decreases, the tissue PO2 to satisfy tissue O2 metabolic needs increases without increasing O2 delivery or extraction. Paramagnetic nanoparticles (PMNPs), synthetized using gadolinium oxide, were coated with the cell permeable Hb allosteric effector L35 (3,5-trichlorophenylureido-phenoxy-methylpropionic acid). L35 decreases Hb affinity for O2 and favors the release of O2. The L35-coated PMNPs (L35-PMNPs) were intravenously infused (10 mg kg-1) to hamsters instrumented with the dorsal window chamber model. A magnetic field of 3 mT was applied to localize the effects of the L35-PMNPs to the window chamber. Systemic O2 transport characteristics and microvascular tissue oxygenation were measured after administration of L35-PMNPs with and without magnetic field. The tissue PO2 in untreated control animals was 25.2 mmHg. L35-PMNPs without magnetic field decreased tissue PO2 to 23.4 mmHg, increased blood pressure, and reduced blood flow, largely due to systemic modification of Hb-O2 affinity. L35-PMNPs with magnetic field increased tissue PO2 to 27.9 mmHg, without systemic or microhemodynamic changes. These results indicate that localized modification of Hb-O2 affinity can increase PO2 of target tissue without affecting systemic O2 delivery or triggering O2 autoregulation mechanisms. This technology can be used to treat local hypoxia and to

  20. Characterization and validation of noninvasive oxygen tension measurements in human glioma xenografts by 19F-MR relaxometry

    Sanden, Boudewijn P.J. van der; Heerschap, Arend; Simonetti, Arjan W.; Rijken, Paul F.J.W.; Peters, Hans P.W.; Stbeen, Georg; Kogel, Albert J. van der

    1999-01-01

    Purpose: The aim of this study was to characterize and to validate noninvasive 19 F-magnetic resonance relaxometry for the measurement of oxygen tensions in human glioma xenografts in nude mice. The following three questions were addressed: 1. When perfluorocarbon compounds (PFCs) are administrated intravenously, which tumor regions are assessed by 19 F-MR relaxometry? 2. Are oxygen tension as detected by 19 F-MR relaxometry (pO 2/relaxo ) comparable to Eppendorf O 2 -electrode measurements (pO 2/electrode )? 3. Can 19 F-MR relaxometry be used to detect oxygen tension changes in tumor tissue during carbogen breathing? Methods and Materials: Slice-selective 19 F-MR relaxometry was carried out with perfluoro-15-crown-5-ether as oxygen sensor. The PFC was injected i.v. 3 days before the 19 F-MR experiments. Two datasets were acquired before and two after the start of carbogen breathing. The distribution of PFCs and necrotic areas were analyzed in 19 F-Spin Echo (SE) density MR images and T 2 -weighted 1 H-SE MR images, respectively. One day after the MR investigations, oxygen tensions were measured by oxygen electrodes in the same slice along two perpendicular tracks. These measurements were followed by (immuno)histochemical analysis of the 2D distribution of perfused microvessels, hypoxic cells, necrotic areas, and macrophages. Results: The PFCs mainly became sequestered in perfused regions at the tumor periphery; thus, 19 F-MR relaxometry probed mean oxygen tensions in these regions throughout the selected MR slice. In perfused regions of the tumor, mean pO 2/relaxo values were comparable to mean pO 2/electrode values, and varied from 0.03 to 9 mmHg. Median pO 2/electrode values of both tracks were lower than mean pO 2/relaxo values, because low pO 2/electrode values that originate from hypoxic and necrotic areas were also included in calculations of median pO 2/electrode values. After 8-min carbogen breathing, the average pO 2/relaxo increase was 3.3 ± 0.8 (SEM

  1. Development of bovine embryos cultured in CR1aa and IVD101 media using different oxygen tensions and culture systems.

    Somfai, Tamás; Inaba, Yasushi; Aikawa, Yoshio; Ohtake, Masaki; Kobayashi, Shuji; Konishi, Kazuyuki; Nagai, Takashi; Imai, Kei

    2010-12-01

    The aim of the present study was to optimise the culture conditions for the in vitro production of bovine embryos. The development of in vitro fertilised bovine oocytes in CR1aa supplemented with 5% calf serum and IVD101 culture media were compared using traditional microdrops and Well of the Well (WOW) culture systems either under 5% or 20% oxygen tension. After 7 days of culture, a significantly higher blastocyst formation rate was obtained for embryos cultured in CR1aa medium compared to those cultured in IVD101, irrespective of O2 tensions and culture systems. The blastocyst formation in IVD101 was suppressed under 20% O2 compared to 5% O2 . Despite their similar total cell numbers, higher rates of inner cell mass (ICM) cells were observed in blastocysts developed in IVD101 medium than in those developed in CR1aa, irrespective of O2 tensions. There was no significant difference in blastocyst formation, total, ICM and trophectoderm (TE) cell numbers between embryos obtained by microdrop and WOW culture systems irrespective of the culture media and O2 tensions used. In conclusion, CR1aa resulted in higher blastocyst formation rates irrespective of O2 tension, whereas IVD101 supported blastocyst formation only under low O2 levels but enhanced the proliferation of ICM cells.

  2. Postnatal follow-up of the oxygenation index, arterial to alveolar oxygen tension ratio and alveolar arterial oxygen tension difference values in neonates with the respiratory distress syndrome treated with conventional ventilatory support.

    Atanasov, A; Despotova-Toleva, L

    1997-01-01

    Recent development of sophisticated intensive care technique for use in newborn infants with the respiratory distress syndrome (RDS) has resulted in changes in the therapeutic strategies and moved the problem of neonatal survival into the realm of new therapeutic realities. At present, the mechanical ventilation methods form an integral part of the intensive care strategy of infants with RDS. They have come to the forefront of infant care because of their successful use in ventilatory support and children survival where other therapeutic modalities have failed. The present prospective observational longitudinal study was designed to assess the real-time convenience, reliability and accuracy of the changes in the oxygenation index (OI), arterial-to-alveolar oxygen tension ratio (a/A PO2) and alveolar-arterial oxygen gradient (A-a)DO2 in ventilator-dependent neonates with RDS, to analyze their feasibility and potential information yield in oxygen inhalation therapy as well as their prognostic implications and predictive value. Twenty neonates with RDS, heralded by respiratory failure which necessitated the initiation of oxygen inhalation therapy and ventilatory support within 24 hours of birth, were enrolled in the study. Ten of the infants survived and the remaining ten died. OI, (a/A PO2) and (A-a)DO2 were followed up sequentially and thoroughly analyzed as the primary outcome measures of the study. The indices were calculated on the basis of the complete monitoring of the ventilatory equipment parameters and acid-base status carried out on an hourly basis. Our results show that: 1. The combination of three indexes (OI, (a/A)PO2 and (A-a)DO2 we propose is a useful discriminating predictor of neonatal lung maturity reflecting arterial blood gas status in ventilator-dependent neonates with RDS. 2. The indices detect the efficacy of the modern conventional ventilatory support with real-time convenience and reliable accuracy forming the cornerstone of clinical decision

  3. High-tension corona controlled ozone generator for environment protection

    Vijayan, T; Patil, Jagadish G

    2010-01-01

    Engineering details of a high voltage driven corona-plasma ozone generator are described. The plasma diode of generator has coaxial cylindrical geometry with cathode located inside anode. Cathode is made of a large number of radial gas nozzles arranged on central tubular mast which admits oxygen gas. The sharp endings of the nozzles along with a set of corona rings create the high electric field at the cathode required for formation of dense corona plume responsible for O 3 evolution. A model of coronal plasma generation and ozone production is presented. The plasma formation is strongly dependent on the electric field and temperature in side diode where a high electron density in a low temperature negative corona is suited for high ozone yields. These are established by suitable regulation of A-K gap, voltage, oxygen pressure, and cathode-nozzle population.

  4. Experimental studies on radiation effects under high pressure oxygen

    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.

  5. Environmental oxygen tension regulates the energy metabolism and self-renewal of human embryonic stem cells.

    Forristal, Catherine E; Christensen, David R; Chinnery, Fay E; Petruzzelli, Raffaella; Parry, Kate L; Sanchez-Elsner, Tilman; Houghton, Franchesca D

    2013-01-01

    Energy metabolism is intrinsic to cell viability but surprisingly has been little studied in human embryonic stem cells (hESCs). The current study aims to investigate the effect of environmental O2 tension on carbohydrate utilisation of hESCs. Highly pluripotent hESCs cultured at 5% O2 consumed significantly more glucose, less pyruvate and produced more lactate compared to those maintained at 20% O2. Moreover, hESCs cultured at atmospheric O2 levels expressed significantly less OCT4, SOX2 and NANOG than those maintained at 5% O2. To determine whether this difference in metabolism was a reflection of the pluripotent state, hESCs were cultured at 5% O2 in the absence of FGF2 for 16 hours leading to a significant reduction in the expression of SOX2. In addition, these cells consumed less glucose and produced significantly less lactate compared to those cultured in the presence of FGF2. hESCs maintained at 5% O2 were found to consume significantly less O2 than those cultured in the absence of FGF2, or at 20% O2. GLUT1 expression correlated with glucose consumption and using siRNA and chromatin immunoprecipitation was found to be directly regulated by hypoxia inducible factor (HIF)-2α at 5% O2. In conclusion, highly pluripotent cells associated with hypoxic culture consume low levels of O2, high levels of glucose and produce large amounts of lactate, while at atmospheric conditions glucose consumption and lactate production are reduced and there is an increase in oxidative metabolism. These data suggest that environmental O2 regulates energy metabolism and is intrinsic to the self-renewal of hESCs.

  6. Modelling of L-valine Repeated Fed-batch Fermentation Process Taking into Account the Dissolved Oxygen Tension

    Tzanko Georgiev

    2009-03-01

    Full Text Available This article deals with synthesis of dynamic unstructured model of variable volume fed-batch fermentation process with intensive droppings for L-valine production. The presented approach of the investigation includes the following main procedures: description of the process by generalized stoichiometric equations; preliminary data processing and calculation of specific rates for main kinetic variables; identification of the specific rates takes into account the dissolved oxygen tension; establishment and optimisation of dynamic model of the process; simulation researches. MATLAB is used as a research environment.

  7. Oxygen tension and riboflavin gradients cooperatively regulate the migration of Shewanella oneidensis MR-1 revealed by a hydrogel-based microfluidic device

    Beum Jun Kim

    2016-09-01

    Full Text Available Shewanella oneidensis (S. oneidensis is a model bacterial strain for studies of bioelectrochemical systems (BESs. It has two extracellular electron transfer pathways: 1 shuttling electrons via an excreted mediator riboflavin; and 2 direct contact between the c-type cytochromes at the cell membrane and the electrode. Despite the extensive use of S. oneidensis in bioelectrochemical systems such as microbial fuel cells and biosensors, many basic microbiology questions about S. oneidensis in the context of BES remain unanswered. Here, we present studies of motility and chemotaxis of S. oneidensis under well controlled concentration gradients of two electron acceptors, oxygen and oxidized form of riboflavin (flavin+ using a newly developed microfluidic platform. Experimental results demonstrate that either oxygen or flavin+ is a chemoattractant to S. oneidensis. The chemotactic tendency of S. oneidensis in a flavin+ concentration gradient is significantly enhanced in an anaerobic in contrast to an aerobic condition. Furthermore, either a low oxygen tension or a high flavin+ concentration considerably enhances the speed of S. oneidensis. This work presents a robust microfluidic platform for generating oxygen and/or flavin+ gradients in an aqueous environment, and demonstrates that two important electron acceptors, oxygen and oxidized riboflavin, cooperatively regulate S. oneidensis migration patterns. The microfluidic tools presented as well as the knowledge gained in this work can be used to guide the future design of BESs for efficient electron production.

  8. Discrepancies between measured changes of radiobiological hypoxic fraction and oxygen tension monitoring using two assay systems

    Sasai, K.; Brown, J.M.

    1994-01-01

    This study was conducted to assess the ability of computerized pO 2 histography to measure changes in tumor oxygenation produced by low oxygen breathing. Female syngeneic C3H/Km mice bearing SCC VII/St carcinomas were used in these experiments. Changes in tumor oxygenation produced by the mice breathing 10% oxygen were assessed with computerized pO2 histography, 3 H-misonidazole binding, and the paired survival curve assay of radiosensitivity. The hypoxic cell fraction of the tumors in mice breathing 10% oxygen was 3.1 times higher than that of tumors in mice breathing normal air determined by an in vivo-in vitro clonogenic assay. Binding of radiolabeled misonidazole to the tumors in mice breathing 10% oxygen was also significantly higher than that to tumors in mice breathing normal air (p 2 value for the tumor. The number of pO 2 readings lower than 5 mmHg in the tumor was not affected by the 10% oxygen breathing. These findings indicate that increases in radiobiological hypoxic fraction produced by lower blood oxygen levels may not correlate well with the results of polarographic measurements of tumor pO 2 levels. 29 refs., 4 figs., 1 tab

  9. Comparison of Preterm and Term Wharton's Jelly-Derived Mesenchymal Stem Cell Properties in Different Oxygen Tensions.

    Balgi-Agarwal, Saloni; Winter, Caitlyn; Corral, Alexis; Mustafa, Shamimunisa B; Hornsby, Peter; Moreira, Alvaro

    2018-06-27

    Mesenchymal stem cells (MSCs) have shown promise as therapeutic agents in treating morbidities associated with premature birth. MSCs derived from the human umbilical cord are easy to isolate and have low immunogenicity and a robust ability to secrete paracrine factors. To date, there are no studies evaluating preterm versus term umbilical cord tissue-derived MSCs. Therefore, our aim was twofold: (1) to compare stem cell properties in preterm versus term MSCs and (2) to examine the impact of oxygen tension on stem cell behavior. Umbilical cord tissue was obtained from 5 preterm and 5 term neonates. The cells were isolated and characterized as MSCs in accordance with the International Society for Cellular Therapy. We exposed MSCs to different oxygen tensions to examine the impact of environmental factors on cell performance. We studied the following stem cell properties: (i) motility, (ii) proliferation, (iii) senescence, (iv) cell viability, (v) colony-forming unit efficiency, and (vi) inflammatory cytokine expression. Under normoxia (21% O2), cells from preterm and term infants had similar properties. Under hypoxic conditions (1% O2), term MSCs had better cell proliferation; however, cells exposed to hyperoxia (90% O2) had the slowest motility and lowest cell viability (p cytokine expression between the groups. The term cells demonstrated more colony-forming efficiency than the preterm cells. In sum, our preliminary findings suggest that MSCs derived from term and preterm umbilical cords have similar characteristics, offering the potential of future autologous/allogeneic MSC transplants in neonates. © 2018 S. Karger AG, Basel.

  10. Detection of cerebral arterial gas embolism using regional cerebral oxygen saturation, quantitative electroencephalography, and brain oxygen tension in the swine

    Weenink, R. P.; Hollmann, M. W.; Stevens, M. F.; Kager, J.; van Gulik, T. M.; van Hulst, R. A.

    2014-01-01

    Cerebral air emboli occur as a complication of invasive medical procedures. The sensitivity of cerebral monitoring methods for the detection of air emboli is not known. This study investigates the utility of electroencephalography and non-invasively measured cerebral oxygen saturation in the

  11. Exogenous and endogenous angiotensin-II decrease renal cortical oxygen tension in conscious rats by limiting renal blood flow.

    Emans, Tonja W; Janssen, Ben J; Pinkham, Maximilian I; Ow, Connie P C; Evans, Roger G; Joles, Jaap A; Malpas, Simon C; Krediet, C T Paul; Koeners, Maarten P

    2016-11-01

    Our understanding of the mechanisms underlying the role of hypoxia in the initiation and progression of renal disease remains rudimentary. We have developed a method that allows wireless measurement of renal tissue oxygen tension in unrestrained rats. This method provides stable and continuous measurements of cortical tissue oxygen tension (PO2) for more than 2 weeks and can reproducibly detect acute changes in cortical oxygenation. Exogenous angiotensin-II reduced renal cortical tissue PO2 more than equi-pressor doses of phenylephrine, probably because it reduced renal oxygen delivery more than did phenylephrine. Activation of the endogenous renin-angiotensin system in transgenic Cyp1a1Ren2 rats reduced cortical tissue PO2; in this model renal hypoxia precedes the development of structural pathology and can be reversed acutely by an angiotensin-II receptor type 1 antagonist. Angiotensin-II promotes renal hypoxia, which may in turn contribute to its pathological effects during development of chronic kidney disease. We hypothesised that both exogenous and endogenous angiotensin-II (AngII) can decrease the partial pressure of oxygen (PO2) in the renal cortex of unrestrained rats, which might in turn contribute to the progression of chronic kidney disease. Rats were instrumented with telemeters equipped with a carbon paste electrode for continuous measurement of renal cortical tissue PO2. The method reproducibly detected acute changes in cortical oxygenation induced by systemic hyperoxia and hypoxia. In conscious rats, renal cortical PO2 was dose-dependently reduced by intravenous AngII. Reductions in PO2 were significantly greater than those induced by equi-pressor doses of phenylephrine. In anaesthetised rats, renal oxygen consumption was not affected, and filtration fraction was increased only in the AngII infused animals. Oxygen delivery decreased by 50% after infusion of AngII and renal blood flow (RBF) fell by 3.3 ml min -1 . Equi-pressor infusion of

  12. Exogenous and endogenous angiotensin‐II decrease renal cortical oxygen tension in conscious rats by limiting renal blood flow

    Emans, Tonja W.; Janssen, Ben J.; Pinkham, Maximilian I.; Ow, Connie P. C.; Evans, Roger G.; Joles, Jaap A.; Malpas, Simon C.; Krediet, C. T. Paul

    2016-01-01

    Key points Our understanding of the mechanisms underlying the role of hypoxia in the initiation and progression of renal disease remains rudimentary.We have developed a method that allows wireless measurement of renal tissue oxygen tension in unrestrained rats.This method provides stable and continuous measurements of cortical tissue oxygen tension (PO2) for more than 2 weeks and can reproducibly detect acute changes in cortical oxygenation.Exogenous angiotensin‐II reduced renal cortical tissue PO2 more than equi‐pressor doses of phenylephrine, probably because it reduced renal oxygen delivery more than did phenylephrine.Activation of the endogenous renin–angiotensin system in transgenic Cyp1a1Ren2 rats reduced cortical tissue PO2; in this model renal hypoxia precedes the development of structural pathology and can be reversed acutely by an angiotensin‐II receptor type 1 antagonist.Angiotensin‐II promotes renal hypoxia, which may in turn contribute to its pathological effects during development of chronic kidney disease. Abstract We hypothesised that both exogenous and endogenous angiotensin‐II (AngII) can decrease the partial pressure of oxygen (PO2) in the renal cortex of unrestrained rats, which might in turn contribute to the progression of chronic kidney disease. Rats were instrumented with telemeters equipped with a carbon paste electrode for continuous measurement of renal cortical tissue PO2. The method reproducibly detected acute changes in cortical oxygenation induced by systemic hyperoxia and hypoxia. In conscious rats, renal cortical PO2 was dose‐dependently reduced by intravenous AngII. Reductions in PO2 were significantly greater than those induced by equi‐pressor doses of phenylephrine. In anaesthetised rats, renal oxygen consumption was not affected, and filtration fraction was increased only in the AngII infused animals. Oxygen delivery decreased by 50% after infusion of AngII and renal blood flow (RBF) fell by 3.3 ml min−1

  13. Cutaneous respirometry by dynamic measurement of mitochondrial oxygen tension for monitoring mitochondrial function in vivo.

    Harms, Floor A; Voorbeijtel, Wilhelmina J; Bodmer, Sander I A; Raat, Nicolaas J H; Mik, Egbert G

    2013-09-01

    Progress in diagnosis and treatment of mitochondrial dysfunction in chronic and acute disease could greatly benefit from techniques for monitoring of mitochondrial function in vivo. In this study we demonstrate the feasibility of in vivo respirometry in skin. Mitochondrial oxygen measurements by means of oxygen-dependent delayed fluorescence of protoporphyrin IX are shown to provide a robust basis for measurement of local oxygen disappearance rate (ODR). The fundamental principles behind the technology are described, together with an analysis method for retrievel of respirometry data. The feasibility and reproducibility of this clinically useful approach are demonstrated in a series of rats. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Membrane culture and reduced oxygen tension enhances cartilage matrix formation from equine cord blood mesenchymal stromal cells in vitro.

    Co, C; Vickaryous, M K; Koch, T G

    2014-03-01

    Ongoing research is aimed at increasing cartilage tissue yield and quality from multipotent mesenchymal stromal cells (MSC) for the purpose of treating cartilage damage in horses. Low oxygen culture has been shown to enhance chondrogenesis, and novel membrane culture has been proposed to increase tissue yield and homogeneity. The objective of this study was to evaluate and compare the effect of reduced oxygen and membrane culture during in vitro chondrogenesis of equine cord blood (CB) MSC. CB-MSC (n = 5 foals) were expanded at 21% oxygen prior to 3-week differentiation in membrane or pellet culture at 5% and 21% oxygen. Assessment included histological examination (H&E, toluidine Blue, immunohistochemistry (IHC) for collagen type I and II), protein quantification by hydroxyproline assay and dimethylmethylene assay, and mRNA analysis for collagen IA1, collagen IIA1, collagen XA1, HIF1α and Sox9. Among treatment groups, 5% membrane culture produced neocartilage most closely resembling hyaline cartilage. Membrane culture resulted in increased wet mass, homogenous matrix morphology and an increase in total collagen content, while 5% oxygen culture resulted in higher GAG and type II collagen content. No significant differences were observed for mRNA analysis. Membrane culture at 5% oxygen produces a comparatively larger amount of higher quality neocartilage. Matrix homogeneity is attributed to a uniform diffusion gradient and reduced surface tension. Membrane culture holds promise for scale-up for therapeutic purposes, for cellular preconditioning prior to cytotherapeutic applications, and for modeling system for gas-dependent chondrogenic differentiation studies. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

  15. Ion release from magnesium materials in physiological solutions under different oxygen tensions.

    Feyerabend, Frank; Drücker, Heiko; Laipple, Daniel; Vogt, Carla; Stekker, Michael; Hort, Norbert; Willumeit, Regine

    2012-01-01

    Although magnesium as degradable biomaterial already showed clinical proof of concepts, the design of new alloys requires predictive in vitro methods, which are still lacking. Incubation under cell culture conditions to obtain "physiological" corrosion may be a solution. The aim of this study was to analyse the influence of different solutions, addition of proteins and of oxygen availability on the corrosion of different magnesium materials (pure Mg, WE43, and E11) with different surface finishing. Oxygen content in solution, pH, osmolality and ion release were determined. Corrosion led to a reduction of oxygen in solution. The influence of oxygen on pH was enhanced by proteins, while osmolality was not influenced. Magnesium ion release was solution-dependent and enhanced in the initial phase by proteins with delayed release of alloying elements. The main corrosion product formed was magnesium carbonate. Therefore, cell culture conditions are proposed as first step toward physiological corrosion.

  16. A multislice single breath-hold scheme for imaging alveolar oxygen tension in humans.

    Hamedani, Hooman; Kadlecek, Stephen J; Emami, Kiarash; Kuzma, Nicholas N; Xu, Yinan; Xin, Yi; Mongkolwisetwara, Puttisarn; Rajaei, Jennia; Barulic, Amy; Wilson Miller, G; Rossman, Milton; Ishii, Masaru; Rizi, Rahim R

    2012-05-01

    Reliable, noninvasive, and high-resolution imaging of alveolar partial pressure of oxygen (p(A)O(2)) is a potentially valuable tool in the early diagnosis of pulmonary diseases. Several techniques have been proposed for regional measurement of p(A)O(2) based on the increased depolarization rate of hyperpolarized (3) He. In this study, we explore one such technique by applying a multislice p(A)O(2) -imaging scheme that uses interleaved-slice ordering to utilize interslice time-delays more efficiently. This approach addresses the low spatial resolution and long breath-hold requirements of earlier techniques, allowing p(A)O(2) measurements to be made over the entire human lung in 10-15 s with a typical resolution of 8.3 × 8.3 × 15.6 mm(3). PO(2) measurements in a glass syringe phantom were in agreement with independent gas analysis within 4.7 ± 4.1% (R = 0.9993). The technique is demonstrated in four human subjects (healthy nonsmoker, healthy former smoker, healthy smoker, and patient with COPD), each imaged six times on 3 different days during a 2-week span. Two independent measurements were performed in each session, consisting of 12 coronal slices. The overall p(A)O(2) mean across all subjects was 95.9 ± 12.2 Torr and correlated well with end-tidal O(2) (R = 0.805, P < 0.0001). The alveolar O(2) uptake rate was consistent with the expected range of 1-2 Torr/s. Repeatable visual features were observed in p(A)O(2) maps over different days, as were characteristic differences among the subjects and gravity-dependent effects. Copyright © 2011 Wiley Periodicals, Inc.

  17. Robust high temperature oxygen sensor electrodes

    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...

  18. Comparison Between Cerebral Tissue Oxygen Tension and Energy Metabolism in Experimental Subdural Hematoma

    Nielsen, Troels Halfeld; Engell, Susanne I; Johnsen, Rikke Aagaard

    2011-01-01

    BACKGROUND: An experimental swine model (n = 7) simulating an acute subdural hematoma (ASDH) was employed (1) to explore the relation between the brain tissue oxygenation (PbtO(2)) and the regional cerebral energy metabolism as obtained by microdialysis, and (2) to define the lowest level of PbtO(2...

  19. Oxygen-tension measurements - The first step towards prevention and early detection of anastomotic leakage

    Tanase, D.; French, P.J.; Komen, N.; Kleinrensink, G.J.; Jeekel, J.; Lange, J.F.; Draaijer, A.

    2007-01-01

    Many patients still die every year as a result of anastomotic leakage after surgery. The medical world needs an objective aid to detect leakage during surgery and during the critical recovery period. We propose a miniature measurement system to detect adequate tissue oxygenation pre- and

  20. Influence of hyperoxia on the number of nucleated cells and oxygen tension in rat bone marrow after whole-body irradiation

    Zima, M.; Vodicka, I.

    1987-01-01

    The cell number in the femur bone marrow of rats determined three days after X-ray or gamma irradiation is inversely proportional to the dose while oxygen tension in the marrow shows direct dependence on the dose. With fractionation of the lethal dose of gamma radiation (9 Gy) into two doses with different time intervals between them, a greater number of bone marrow cells and a smaller oxygen tension are reached on the 3rd day after the second dose, reflecting the extent of bone marrow repair. A short-term hyperoxia (95% O 2 + 5% CO 2 ) lasting 20 min from the end of exposure compared with the euoxic conditions induced, on the 3rd day after the second fraction, a nonsignificant but reproducible increase in the marrow cell number and a decrease in partial oxygen tension in the distal part of femur marrow. The results obtained testify that immediate short-term hyperoxia facilitates regeneration of the marrow and that a greater number of cells accompanied by greater metabolic activity and oxygen consumption decrease the partial oxygen tension measured on the 3rd day following the last exposure. (author). 7 figs., 16 refs

  1. Correlation of cutaneous tension distribution and tissue oxygenation with acute external tissue expansion

    Marquardt C

    2009-11-01

    Full Text Available Abstract Today, the biomechanical fundamentals of skin expansion are based on viscoelastic models of the skin. Although many studies have been conducted in vitro, analyses performed in vivo are rare. Here, we present in vivo measurements of the expansion at the skin surface as well as measurement of the corresponding intracutaneous oxygen partial pressure. In our study the average skin stretching was 24%, with a standard deviation of 11%, excluding age or gender dependency. The measurement of intracutaneous oxygen partial pressure produced strong inter-individual fluctuations, including initial values at the beginning of the measurement, as well as varying individual patient reactions to expansion of the skin. Taken together, we propose that even large defect wounds can be closed successfully using the mass displacement caused by expansion especially in areas where soft, voluminous tissue layers are present.

  2. Effect of low oxygen tension on the biological characteristics of human bone marrow mesenchymal stem cells

    Kim, Dae Seong; Ko, Young Jong; Lee, Myoung Woo; Park, Hyun Jin; Park, Yoo Jin; Kim, Dong-Ik; Sung, Ki Woong; Koo, Hong Hoe; Yoo, Keon Hee

    2016-01-01

    Culture of mesenchymal stem cells (MSCs) under ambient conditions does not replicate the low oxygen environment of normal physiological or pathological states and can result in cellular impairment during culture. To overcome these limitations, we explored the effect of hypoxia (1 % O2) on the biological characteristics of MSCs over the course of different culture periods. The following biological characteristics were examined in human bone marrow-derived MSCs cultured under hypoxia for 8 week...

  3. Adverse effects of reduced oxygen tension on the proliferative capacity of rat kidney and insulin-secreting cell lines involve DNA damage and stress responses

    Chen Jianhua; Jones, R. Huw; Tarry-Adkins, Jane; Smith, Noel H.; Ozanne, Susan E.

    2008-01-01

    Standard cell culture conditions do not reflect the physiological environment in terms of oxygen tension (20% vs 3%). The effects of lowering oxygen tension on cell proliferation in culture can be beneficial as well as detrimental depending on the cell line studied, but the molecular mechanism underlying such effects is not fully understood. We observed that the proliferative capacity of the rat cell lines NRK and INS-1 was inhibited when cultured under 3% oxygen as compared to 20% oxygen. Suppression of proliferation in NRK cells was accompanied by induction of DNA double strand breaks whereas in INS-1 cells it was accompanied by up-regulation of p53 and p27. Although Sirt1 was up-regulated in both cell lines by 3% oxygen the effects on antioxidant enzymes (MnSOD, CuZnSOD and catalase) were cell line specific. Marked up-regulation of heme oxygenase-1 (HO-1) was detected in both NRK and INS-1 cells when cultured in 3% oxygen. HO-1 expression can be readily induced by exposure to hydrogen peroxide in culture. These results suggest that reduced oxygen tension suppresses the proliferative capacity of these two cell lines through a stress response that is similar to an oxidative stress response but the molecular events that lead to the reduced cell proliferation are cell line specific

  4. Variations in tumour oxygen tension (pO2) during accelerated radiotherapy of head and neck carcinoma

    Guichard, M.; Eschwege, F.; Luboinski, B.; Wibault, P.; Weeger, P.; Lusinchi, A.; Lartigau, E.

    1998-01-01

    The study was performed to assess the effect of accelerated radiotherapy on oxygenation of primary tumours and metastatic nodes in patients with advanced head and neck tumours. In 14 patients with head and neck tumour, oxygen tension (pO 2 ) was evaluated in normal tissues and tumours (primary tumour or metastatic neck node) before (0 Gy) and after 2 weeks (32 Gy) of accelerated radiotherapy (70 Gy in 3.5 weeks, with three daily fractions). Radiotherapy was combined with carbogen breathing in 5 patients. pO 2 was measured using a polarographic technique. For pooled normal tissues, median pO 2 was 38 mmHg before treatment and 46 mmHg after 2 weeks. For tumours, very low values ( 2 12 mmHg before treatment versus 26 mmHg after 2 weeks, P 2 was 44 mmHg at 2 weeks, compared with 13.5 mmHg before treatment (P=0.05). Very low pO 2 values, corresponding to tumour hypoxia, were found in the tumours (primary and metastatic neck nodes) prior to accelerated treatment. During the first 2 weeks of accelerated treatment, an increase in median pO 2 was found in nine of the 14 tumours, together with a decrease in the frequency of very low values. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  5. IVF/ICSI outcomes after culture of human embryos at low oxygen tension: a meta-analysis

    Gomes Sobrinho David B

    2011-11-01

    Full Text Available Abstract Background Improved pregnancy, implantation, and birth rates have been reported after the use of reduced O2 concentration during embryo culture, mainly due to a reduction of the cumulative detrimental effects of reactive oxygen species. However, some studies have failed to report any positive effects. The objective of this meta-analysis was to evaluate the effect of a low-O2 environment on IVF/intracytoplasmic sperm injection (ICSI outcomes. Methods All available published and ongoing randomised trials that compared the effects of low (~5%; OC~5 and atmospheric (~20%; OC~20 oxygen concentrations on IVF/ICSI outcomes were included. Search strategies included online surveys of databases from 1980 to 2011. The outcomes measured were fertilisation rate, implantation rate and ongoing pregnancy rates. The fixed effects model was used to calculate the odds ratio. Results Seven studies were included in this analysis. The pooled fertilisation rate did not differ significantly (P = 0.54 between the group of oocytes cultured at low O2 tension and the group at atmospheric O2 tension. Concerning all cycles, the implantation (P = 0.06 and ongoing pregnancy (P = 0.051 rates were not significantly different between the group receiving transferred sets containing only OC~5 embryos and the group receiving transferred sets with only OC~20 embryos. In a meta-analysis performed for only those trials in which embryos were transferred on day 2/3, implantation (P = 0.63 and ongoing pregnancy (P = 0.19 rates were not significantly different between the groups. In contrast, when a meta-analysis was performed using only trials in which embryos were transferred on days 5 and 6 (at the blastocyst stage, the group with transferred sets of only OC~5 embryos showed a statistically significantly higher implantation rate (P = 0.006 than the group receiving transferred sets with only OC~20 embryos, although the ongoing pregnancy (P = 0.19 rates were not significantly

  6. Endothelial cell respiration is affected by the oxygen tension during shear exposure: role of mitochondrial peroxynitrite.

    Jones, Charles I; Han, Zhaosheng; Presley, Tennille; Varadharaj, Saradhadevi; Zweier, Jay L; Ilangovan, Govindasamy; Alevriadou, B Rita

    2008-07-01

    Cultured vascular endothelial cell (EC) exposure to steady laminar shear stress results in peroxynitrite (ONOO(-)) formation intramitochondrially and inactivation of the electron transport chain. We examined whether the "hyperoxic state" of 21% O(2), compared with more physiological O(2) tensions (Po(2)), increases the shear-induced nitric oxide (NO) synthesis and mitochondrial superoxide (O(2)(*-)) generation leading to ONOO(-) formation and suppression of respiration. Electron paramagnetic resonance oximetry was used to measure O(2) consumption rates of bovine aortic ECs sheared (10 dyn/cm(2), 30 min) at 5%, 10%, or 21% O(2) or left static at 5% or 21% O(2). Respiration was inhibited to a greater extent when ECs were sheared at 21% O(2) than at lower Po(2) or left static at different Po(2). Flow in the presence of an endothelial NO synthase (eNOS) inhibitor or a ONOO(-) scavenger abolished the inhibitory effect. EC transfection with an adenovirus that expresses manganese superoxide dismutase in mitochondria, and not a control virus, blocked the inhibitory effect. Intracellular and mitochondrial O(2)(*-) production was higher in ECs sheared at 21% than at 5% O(2), as determined by dihydroethidium and MitoSOX red fluorescence, respectively, and the latter was, at least in part, NO-dependent. Accumulation of NO metabolites in media of ECs sheared at 21% O(2) was modestly increased compared with ECs sheared at lower Po(2), suggesting that eNOS activity may be higher at 21% O(2). Hence, the hyperoxia of in vitro EC flow studies, via increased NO and mitochondrial O(2)(*-) production, leads to enhanced ONOO(-) formation intramitochondrially and suppression of respiration.

  7. Diet-induced weight loss decreases adipose tissue oxygen tension with parallel changes in adipose tissue phenotype and insulin sensitivity in overweight humans

    Vink, R.G.; Roumans, N.J.; Čajlaković, M.; Cleutjens, J.P.M.; Boekschoten, M.V.; Fazelzadeh, P.; Vogel, M.A.A.; Blaak, E.E.; Mariman, E.C.; Baak, van M.A.; Goossens, G.H.

    2017-01-01

    Background/objectives: Although adipose tissue (AT) hypoxia is present in rodent models of obesity, evidence for this in humans is limited. Here, we investigated the effects of diet-induced weight loss (WL) on abdominal subcutaneous AT oxygen tension (pO 2), AT blood flow (ATBF), AT capillary

  8. Matrix forming characteristics of inner and outer human meniscus cells on 3D collagen scaffolds under normal and low oxygen tensions.

    Croutze, Roger; Jomha, Nadr; Uludag, Hasan; Adesida, Adetola

    2013-12-13

    Limited intrinsic healing potential of the meniscus and a strong correlation between meniscal injury and osteoarthritis have prompted investigation of surgical repair options, including the implantation of functional bioengineered constructs. Cell-based constructs appear promising, however the generation of meniscal constructs is complicated by the presence of diverse cell populations within this heterogeneous tissue and gaps in the information concerning their response to manipulation of oxygen tension during cell culture. Four human lateral menisci were harvested from patients undergoing total knee replacement. Inner and outer meniscal fibrochondrocytes (MFCs) were expanded to passage 3 in growth medium supplemented with basic fibroblast growth factor (FGF-2), then embedded in porous collagen type I scaffolds and chondrogenically stimulated with transforming growth factor β3 (TGF-β3) under 21% (normal or normoxic) or 3% (hypoxic) oxygen tension for 21 days. Following scaffold culture, constructs were analyzed biochemically for glycosaminoglycan production, histologically for deposition of extracellular matrix (ECM), as well as at the molecular level for expression of characteristic mRNA transcripts. Constructs cultured under normal oxygen tension expressed higher levels of collagen type II (p = 0.05), aggrecan (p oxygen tension. There was no significant difference in expression of these genes between scaffolds seeded with MFCs isolated from inner or outer regions of the tissue following 21 days chondrogenic stimulation (p > 0.05). Cells isolated from inner and outer regions of the human meniscus demonstrated equivalent differentiation potential toward chondrogenic phenotype and ECM production. Oxygen tension played a key role in modulating the redifferentiation of meniscal fibrochondrocytes on a 3D collagen scaffold in vitro.

  9. Critical oxygen tension and the effect of hypoxia on the oxygen consumption of the striped catfish, Pangasius hypophthaimos (Pangasiidae)

    Lefevre, S.; Bayley, Mark; Wang, Tobias

    2008-01-01

    The striped catfish (Pangasius hypophthalmus) is an air-breathing teleost that uses a modified swim bladder for aerial gas exchange. Pangasius is of enormous importance for aquaculture industry in the Mekong Delta(Vietnam), but little is known about its physiology. We have initiated a series...... consumption (VO2), measured with intermittent closed respirometry, was 67.8 ± 5.1 mLO2/kg/h when the fish were maintained without access to air at 27 °C. The critical oxygen tension (Pcrit) at these conditions was 57.9 ± 8.9 mmHg (N = 7). The metabolic response to aquatic hypoxia was studied in fish subjected....... The ontogenetic effect of environmental PO2 on metabolism is currently under investigation with fish being reared in 30%, 60% and 100% saturation. Data on resting VO2and Pcrit will be presented and discussed for these animals....

  10. Improving corrosion resistance of post-tensioned substructures emphasizing high performance grouts

    Schokker, Andrea Jeanne

    The use of post-tensioning in bridges can provide durability and structural benefits to the system while expediting the construction process. When post-tensioning is combined with precast elements, traffic interference can be greatly reduced through rapid construction. Post-tensioned concrete substructure elements such as bridge piers, hammerhead bents, and straddle bents have become more prevalent in recent years. Chloride induced corrosion of steel in concrete is one of the most costly forms of corrosion each year. Coastal substructure elements are exposed to seawater by immersion or spray, and inland bridges may also be at risk due to the application of deicing salts. Corrosion protection of the post-tensioning system is vital to the integrity of the structure because loss of post-tensioning can result in catastrophic failure. Documentation for durability design of the grout, ducts, and anchorage systems is very limited. The objective of this research is to evaluate the effectiveness of corrosion protection measures for post-tensioned concrete substructures by designing and testing specimens representative of typical substructure elements using state-of-the-art practices in aggressive chloride exposure environments. This was accomplished through exposure testing of twenty-seven large-scale beam specimens and ten large-scale column specimens. High performance grout for post-tensioning tendon injection was also developed through a series of fresh property tests, accelerated exposure tests, and a large-scale pumping test to simulate field conditions. A high performance fly ash grout was developed for applications with small vertical rises, and a high performance anti-bleed grout was developed for applications involving large vertical rises such as tall bridge piers. Long-term exposure testing of the beam and column specimens is ongoing, but preliminary findings indicate increased corrosion protection with increasing levels of post-tensioning, although traditional

  11. The behavior of high-strength unidirectional composites under tension with superposed hydrostatic pressure

    Zinoviev, P.A.; Tsvetkov, S.V.; Kulish, G.G.; Berg, van den R.W.; Schepdael, van L.J.M.M.

    2001-01-01

    Three types of high-strength unidirectional composite materials were studied under longitudinal tension with superposed high hydrostatic pressure. Reinforcing fibers were T1000G carbon, S2 glass and Zylon PBO fibers; the Ciba 5052 epoxy resin was used as matrix. The composites were tested under

  12. Additive influence of extracellular pH, oxygen tension, and pressure on invasiveness and survival of human osteosarcoma cells

    Takao eMatsubara

    2013-07-01

    Full Text Available BACKGROUND/PURPOSE:The effects of chemical and physical interactions in the microenvironment of solid tumors have not been fully elucidated. We hypothesized that acidosis, hypoxia, and elevated interstitial fluid pressure (eIFP have additive effects on tumor cell biology and lead to more aggressive behavior during tumor progression. We investigated this phenomenon using 3 human osteosarcoma cell lines and a novel in vitro cell culture apparatus. MATERIALS AND METHODS:U2OS, SaOS, and MG63 cell lines were cultured in media adjusted to various pH levels, oxygen tension (hypoxia 2% O2, normoxia 20% O2, and hydrostatic gauge pressure (0 or 50 mm Hg. Growth rate, apoptosis, cell cycle parameters, and expression of mRNA for proteins associated with invasiveness and tumor microenvironment (CA IX, VEGF-A, HIF-1A, MMP-9, and TIMP-2 were analyzed. Levels of CA IX, HIF-1α, and MMP-9 were measured using immunofluorescence. The effect of pH on invasiveness was evaluated in a Matrigel chamber assay.RESULTS: Within the acidic–hypoxic–pressurized conditions that simulate the microenvironment at a tumor’s center, invasive genes were upregulated, but the cell cycle was downregulated. The combined influence of acidosis, hypoxia, and IFP promoted invasiveness and angiogenesis to a greater extent than did pH, pO2, or eIFP individually. Significant cell death after brief exposure to acidic conditions occurred in each cell line during acclimation to acidic media, while prolonged exposure to acidic media resulted in reduced cell death. Furthermore, 48-hour exposure to acidic conditions promoted tumor invasiveness in the Matrigel assay. CONCLUSION: Our findings demonstrate that tumor microenvironmental parameters—particularly pH, pO2, and eIFP—additively influence tumor proliferation, invasion, metabolism, and viability to enhance cell survival.

  13. Optimizing the calculation of DM,CO and VC via the single breath single oxygen tension DLCO/NO method.

    Coffman, Kirsten E; Taylor, Bryan J; Carlson, Alex R; Wentz, Robert J; Johnson, Bruce D

    2016-01-15

    Alveolar-capillary membrane conductance (D(M,CO)) and pulmonary-capillary blood volume (V(C)) are calculated via lung diffusing capacity for carbon monoxide (DL(CO)) and nitric oxide (DL(NO)) using the single breath, single oxygen tension (single-FiO2) method. However, two calculation parameters, the reaction rate of carbon monoxide with blood (θ(CO)) and the D(M,NO)/D(M,CO) ratio (α-ratio), are controversial. This study systematically determined optimal θ(CO) and α-ratio values to be used in the single-FiO2 method that yielded the most similar D(M,CO) and V(C) values compared to the 'gold-standard' multiple-FiO2 method. Eleven healthy subjects performed single breath DL(CO)/DL(NO) maneuvers at rest and during exercise. D(M,CO) and V(C) were calculated via the single-FiO2 and multiple-FiO2 methods by implementing seven θ(CO) equations and a range of previously reported α-ratios. The RP θ(CO) equation (Reeves, R.B., Park, H.K., 1992. Respiration Physiology 88 1-21) and an α-ratio of 4.0-4.4 yielded DM,CO and VC values that were most similar between methods. The RP θ(CO) equation and an experimental α-ratio should be used in future studies. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Oxygen tension in human tumours measured with polarographic needle electrodes and its relationship to vascular density, necrosis and hypoxia

    Lyng, Heidi; Sundfoer, Kolbein; Rofstad, Einar K.

    1997-01-01

    Background and purpose: The use of polarographic needle electrodes for measurement of oxygen tension (pO 2 ) in tumours requires documentation of the validity of the method. In the present work the pO 2 values measured polarographically with the Eppendorf pO 2 histograph in human tumours were compared with the histological appearance of the tumour tissue, i.e. vascular density, fraction of necrosis and fraction of hypoxic tissue, to investigate whether the measurements reflected the expected pO 2 . Materials and methods: The pO 2 was measured in cervix tumours in patients and in human melanoma xenografted tumours in athymic mice. Vascular density was determined in the cervix tumours by histological analysis of biopsies from the pO 2 measurement tracks. Fraction of necrosis and fraction of hypoxic tissue, i.e. tissue binding the hypoxia marker pimonidazole, were determined in the melanomas by analysis of histological sections from the tumour planes in which the pO 2 measurements were performed. Results: The pO 2 distributions showed large intratumour heterogeneity. In cervix tumours, tumour regions with vascular density (vascular length per unit tissue volume) in the range of 47-77 mm/mm 3 showed higher pO 2 than tumour regions with vascular density in the range of 20-47 mm/mm 3 , which in turn showed higher pO 2 than tumour regions with vascular density in the range of 0-20 mm/mm 3 . In melanomas, tumour regions in which necrosis and hypoxia constituted more than 50% of the tissue showed lower pO 2 than other tumour regions. Conclusions: The pO 2 measured in the tumours was consistent with the histological appearance of the tissue in which the measurements were performed, suggesting that reliable pO 2 distributions of tumours can be obtained with polarographic needle electrodes

  15. Modelling of tension stiffening for normal and high strength concrete

    Christiansen, Morten Bo; Nielsen, Mogens Peter

    1998-01-01

    form the model is extended to apply to biaxial stress fields as well. To determine the biaxial stress field, the theorem of minimum complementary elastic energy is used. The theory has been compared with tests on rods, disks, and beams of both normal and high strength concrete, and very good results...

  16. The effect of oxygen tension in the sediment on the behaviour of waste radionuclides at the NEA Atlantic dumpsite

    Rutgers van der Loeff, M.M.; Waijers, D.A.

    1985-01-01

    Predictions of the transport and fate of waste radionuclides at the NEA Atlantic dumpsite require a knowledge of the behaviour of these nuclides within the sediment. Since redox conditions are known to influence the mobility of many elements in deep-sea sediments, we have investigated the speciation of some trace elements in relation to the dissolved oxygen concentration in sediments from the dumpsite. Dissolved oxygen in these sediments penetrates mostly between 50 and 100 cm, although at topographic highs and on hillsides oxygen penetrates more than 2 m into the sediment because of the special hydrodynamic and sedimentological conditions there. Remobilization at lowered redox potentials below the depth where oxygen reaches zero causes an upward diffusive transport of Mn and the manganese-associated trace metals Co and Ni. Whether this diagenetic mobilization influences other elements such as rare earth elements and actinides as well, remains to be investigated. Under normal sedimentological condition this mobilization can not be expected to return radioactivity to the water column through an oxidized sediment layer of 50 cm. However, burial of radioactivity to depths beyond the reach of deep burrowing organisms can be significantly delayed. Kd values (solid/dissolved partition coefficients) of redox sensitive elements vary over orders of magnitude and are inappropriate to model the behaviour of these elements in sediments with redox gradients

  17. Prediction of inspired oxygen fraction for targeted arterial oxygen tension following open heart surgery in non-smoking and smoking patients.

    Bou-Khalil, Pierre; Zeineldine, Salah; Chatburn, Robert; Ayyoub, Chakib; Elkhatib, Farouk; Bou-Akl, Imad; El-Khatib, Mohamad

    2017-10-01

    Simple and accurate expressions describing the P a O 2 -F i O 2 relationship in mechanically ventilated patients are lacking. The current study aims to validate a novel mathematical expression for accurate prediction of the fraction of inspired oxygen that will result in a targeted arterial oxygen tension in non-smoking and smoking patients receiving mechanical ventilation following open heart surgeries. One hundred P a O 2 -F i O 2 data pairs were obtained from 25 non-smoking patients mechanically ventilated following open heart surgeries. One data pair was collected at each of F i O 2 of 40, 60, 80, and 100% while maintaining same mechanical ventilation support settings. Similarly, another 100 hundred P a O 2 -F i O 2 data pairs were obtained from 25 smoking patients mechanically ventilated following open heart surgeries. The utility of the new mathematical expression in accurately describing the P a O 2 -F i O 2 relationship in these patients was assessed by the regression and Bland-Altman analyses. Significant correlations were seen between the true and estimated F i O 2 values in non-smoking (r 2  = 0.9424; p < 0.05) and smoking (r 2  = 0.9466; p < 0.05) patients. Tight biases between the true and estimated F i O 2 values for non-smoking (3.1%) and smoking (4.1%) patients were observed. Also, significant correlations were seen between the true and estimated P a O 2 /F i O 2 ratios in non-smoking (r 2  = 0.9530; p < 0.05) and smoking (r 2  = 0.9675; p < 0.05) patients. Tight biases between the true and estimated P a O 2 /F i O 2 ratios for non-smoking (-18 mmHg) and smoking (-16 mmHg) patients were also observed. The new mathematical expression for the description of the P a O 2 -F i O 2 relationship is valid and accurate in non-smoking and smoking patients who are receiving mechanical ventilation for post cardiac surgery.

  18. Prices high, tensions ease and a new OPEC is formed

    Anon

    2006-01-01

    Crude oil prices rose on news that BP was to shut-in its 400,000 bpd Prudhoe Bay field, following the discovery of corrosion in a pipeline serving the field. Dated BFO went to a record high of $78.72/bbl on 8th August. Speculation that refiners on the US West Coast would seek to replace the lost Alaska North Slope crude with supplies from the Asia/Pacific region caused prices to rise there as well. US crude prices were rather less affected than elsewhere by events in Alaska as it rapidly became clear that stock levels were sufficient to deal with any loss of production. It also emerged that BP was able to keep about half of Prudhoe Bay in production. By that time, however, oil markets had latched on to an entirely different source of worry. The announcement in London that police had uncovered a plot to blow-up aeroplanes crossing the Atlantic led to concerns of a sharp fall in passenger travel. Traders were not simply worried about the effect of this on the demand for jet fuel, but expressed concerns of a more general loss of business confidence across the world. Fears over a fall in jet fuel consumption did not appear to have spread to Singapore, where jet kerosine traded at an all-time high of $91.75/bbl early in August. (author)

  19. A high reliability oxygen deficiency monitoring system

    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

  20. A high reliability oxygen deficiency monitoring system

    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

  1. Effect of tension lap splice on the behavior of high strength concrete (HSC beams

    Ahmed El-Azab

    2014-12-01

    Full Text Available In the recent years, many research efforts have been carried out on the bond strength between normal strength concrete (NSC and reinforcing bars spliced in tension zones in beams. Many codes gave a minimum splice length for tension and compression reinforcement as a factor of the bar diameter depending on many parameters such as concrete strength, steel yield stress, shape of bar end, shape of bar surface and also bar location. Also, codes gave another restriction about the percentage of total reinforcement to be spliced at the same time. Comparatively limited attention has been directed toward the bond between high strength concrete (HSC and reinforcing bars spliced in tension zones in beams. HSC has high modulus of elasticity, high density and long-term durability. This research presents an experimental study on the bond between high strength concrete (HSC and reinforcing bars spliced in tension zones in beams. It reports the influence of several parameters on bond in splices. The parameters covered are casting position, splice length as a factor of bar diameter, bar diameter and reinforcement ratio. The research involved tests on sixteen simply-supported beams of 1800 mm span, 200 mm width and 400 mm thickness made of HSC. In each beam, the total tensile steel bars were spliced in the constant moment zone. Crack pattern, crack propagation, cracking load, failure load and mi span deflection were recorded and analyzed to study the mentioned parameters effect.

  2. High-power generator of singlet oxygen

    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

  3. Bimodular high temperature planar oxygen gas sensor

    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.

  4. Evaluation of the clamping force in high tension bolt by using the ultrasonic nonlinearity

    Jang, Kyung Young; Cheon, Hae Wha; Ha, Hob; Park, Man Sick; Kim, No You

    2005-01-01

    High tension bolts have been used widely for the clamping of many kinds of large structure. Therefore, its estimation has been regarded as main issue in the maintenance of high tension bolts. This paper proposes a novel method using the ultrasonic nonlinearity, which is based on the dependency of sound speed on the stress. For this we introduce nonlinear elastic constants in the stress-strain relationship, and derive the sound speed as a linear function of stress. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out: The first one is to measure the sound speed when the bolt is stressed by the tension tester. The result showed good agreement with the expected linear relationship between the sound speed and the axial stress. The second one is to measure the sound speed when the bolt is stressed by the torque wrench. The results showed that the sound speed was decreased when the torque was increased. From these results we can say that the proposed method is enough useful to evaluate the clamping force in the high tension bolt.

  5. Tensions in the meeting between institutional logics and identities in Swedish folk high schools

    Runesdotter, Caroline

    2011-01-01

    Swedish folk high schools previously held an autonomous position with their own courses, specially trained teachers and the teachers’ association. With the introduction of market-like structures in adult education a variety of providers including folk high schools have become involved in the competition for public and private educational commissions. This article focuses on the tensions at folk high schools when perceived dependence on income from competitive commissions results in new practi...

  6. Oxygen tension regulates the miRNA profile and bioactivity of exosomes released from extravillous trophoblast cells - Liquid biopsies for monitoring complications of pregnancy.

    Grace Truong

    Full Text Available Our understanding of how cells communicate has undergone a paradigm shift since the recent recognition of the role of exosomes in intercellular signaling. In this study, we investigated whether oxygen tension alters the exosome release and miRNA profile from extravillous trophoblast (EVT cells, modifying their bioactivity on endothelial cells (EC. Furthermore, we have established the exosomal miRNA profile at early gestation in women who develop pre-eclampsia (PE and spontaneous preterm birth (SPTB. HTR-8/SVneo cells were used as an EVT model. The effect of oxygen tension (i.e. 8% and 1% oxygen on exosome release was quantified using nanocrystals (Qdot® coupled to CD63 by fluorescence NTA. A real-time, live-cell imaging system (Incucyte™ was used to establish the effect of exosomes on EC. Plasma samples were obtained at early gestation (<18 weeks and classified according to pregnancy outcomes. An Illumina TrueSeq Small RNA kit was used to construct a small RNA library from exosomal RNA obtained from EVT and plasma samples. The number of exosomes was significantly higher in EVT cultured under 1% compared to 8% oxygen. In total, 741 miRNA were identified in exosomes from EVT. Bioinformatic analysis revealed that these miRNA were associated with cell migration and cytokine production. Interestingly, exosomes isolated from EVT cultured at 8% oxygen increased EC migration, whilst exosomes cultured at 1% oxygen decreased EC migration. These changes were inversely proportional to TNF-α released from EC. Finally, we have identified a set of unique miRNAs in exosomes from EVT cultured at 1% oxygen and exosomes isolated from the circulation of mothers at early gestation, who later developed PE and SPTB. We suggest that aberrant exosomal signalling by placental cells is a common aetiological factor in pregnancy complications characterised by incomplete SpA remodeling and is therefore a clinically relevant biomarker of pregnancy complications.

  7. Interfacial tension measurement between CO2 and brines under high temperature and elevated pressure conditions

    Li, X.; Boek, E. S.; Maitland, G. C.; Trusler, J. P. M.

    2012-04-01

    We have investigated the dependence of interfacial tension of (CO2 + brine) on temperature, pressure and salinity (including both salt type and molality) over the range of conditions applicable to CO2 storage in saline aquifers. The study covered a wide range of measurements of the interfacial tensions between carbon dioxide and (NaCl + KCl)(aq), CaCl2(aq), MgCl2(aq), Na2SO4(aq), KHCO3(aq), NaHCO3(aq) and two laboratory constructed brines with molality ranging from (0.3 to 5.0) mol·kg-1. The measurements were made at temperatures between (298 and 448) K at various pressures up to 50 MPa, using the pendant drop method in a high-pressure view cell filled with water-saturated CO2. The drop to be imaged was created by injecting brine from a high-pressure syringe pump into a capillary sealed through the top of the cell. The expanded uncertainties of the experimental state variables at 95 % confidence are +0.05 K in temperature and +70 kPa in pressure. For the interfacial tension, the overall expanded relative uncertainty at 95 % confidence was +1.6%. The experimental results show that interfacial tension for all the systems increases linearly with molality, indicating that relatively few measurements and simple interpolation procedures are adequate for describing this property accurately over wide ranges of conditions.

  8. HIGH PERFORMANCE CERIA BASED OXYGEN MEMBRANE

    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...

  9. Single-Step Fabrication of High-Density Microdroplet Arrays of Low-Surface-Tension Liquids.

    Feng, Wenqian; Li, Linxian; Du, Xin; Welle, Alexander; Levkin, Pavel A

    2016-04-01

    A facile approach for surface patterning that enables single-step fabrication of high-density arrays of low-surface-tension organic-liquid microdroplets is described. This approach enables miniaturized and parallel high-throughput screenings in organic solvents, formation of homogeneous arrays of hydrophobic nanoparticles, polymer micropads of specific shapes, and polymer microlens arrays. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Simulation of press-forming for automobile part using ultra high tension steel

    Tanabe I.

    2012-08-01

    Full Text Available In recent years, ultra high tension steel has gradually been used in the automobile industry. The development of press-forming technology is now essential by reason of its high productivity and high product quality. In this study, tensile tests were performed with a view to understanding the material properties. Press-forming tests were then carried out with regard to the behaviors of spring back and deep-drawability, and manufacturing a real product. The ultra high tension steel used in the experiments had a thickness of 1 mm and a tensile strength of 1000 MPa. Finally, simulations of spring back, deep-drawability and manufacturing a real product in ultra high tension steel were conducted and evaluated in order to calculate the optimum-press-forming conditions and the optimum shape of the die. FEM with non-linear and dynamic analysis using Euler-Lagrange’s element was used for the simulations. It is concluded from the results that (1 the simulations conformed to the results of the experiments (2 the simulations proved very effective for calculating the optimum press conditions and die shape.

  11. Influence of copper high-tension lines on plants and soils

    Kraal, H.; Ernst, W.

    1976-09-01

    The copper contents of plants and soils were determined in relation to the distance from copper high-tension lines. In the vicinity of the cables clayey and fenny soils had demonstrably higher copper contents, due to corrosion of the cables, than regions 20 m and more outside the high-tension lines. On these soils, however, copper accumulation in the plants was low in comparison with those from a sandy soil, although this soil itself showed no copper increase in relation to the cables. The contaminated plants may present a risk of poisoning for sheep within a 20 m distance on both sides of the cables. No changes in plant species composition and in the copper tolerance of Agrostis tenuis were observed.

  12. "Train surfers": analysis of 23 cases of electrical burns caused by high tension railway overhead cables.

    Sternick, I; Gomes, R D; Serra, M C; Radwanski, H N; Pitanguy, I

    2000-08-01

    The term "train surfers" describes a group of adolescents from the outskirts of the city of Rio de Janeiro, who are compelled by the overcrowded railway trains to travel on the roofs of the wagons. Collision with electrical high-tension wires is a relatively frequent occurrence, causing extensive and complex injuries. This study analyzes this clinical and surgical phenomenon which has caused over 100 fatalities in more than 200 registered accidents over the past 10 years.

  13. Non-invasive high throughput approach for protein hydrophobicity determination based on surface tension.

    Amrhein, Sven; Bauer, Katharina Christin; Galm, Lara; Hubbuch, Jürgen

    2015-12-01

    The surface hydrophobicity of a protein is an important factor for its interactions in solution and thus the outcome of its production process. Yet most of the methods are not able to evaluate the influence of these hydrophobic interactions under natural conditions. In the present work we have established a high resolution stalagmometric method for surface tension determination on a liquid handling station, which can cope with accuracy as well as high throughput requirements. Surface tensions could be derived with a low sample consumption (800 μL) and a high reproducibility (content. The protein influence on the solutions' surface tension was correlated to the hydrophobicity of lysozyme, human lysozyme, BSA, and α-lactalbumin. Differences in proteins' hydrophobic character depending on pH and species could be resolved. Within this work we have developed a pH dependent hydrophobicity ranking, which was found to be in good agreement with literature. For the studied pH range of 3-9 lysozyme from chicken egg white was identified to be the most hydrophilic. α-lactalbumin at pH 3 exhibited the most pronounced hydrophobic character. The stalagmometric method occurred to outclass the widely used spectrophotometric method with bromophenol blue sodium salt as it gave reasonable results without restrictions on pH and protein species. © 2015 Wiley Periodicals, Inc.

  14. Interfacial Tension and Surface Pressure of High Density Lipoprotein, Low Density Lipoprotein, and Related Lipid Droplets

    Ollila, O. H. S.; Lamberg, A.; Lehtivaara, M.

    2012-01-01

    ) are essentially lipid droplets surrounded by specific proteins, their main function being to transport cholesterol. Interfacial tension and surface pressure of these particles are of great interest because they are related to the shape and the stability of the droplets and to protein adsorption at the interface....... Here we use coarse-grained molecular-dynamics simulations to consider a number of related issues by calculating the interfacial tension in protein-free lipid droplets, and in HDL and LDL particles mimicking physiological conditions. First, our results suggest that the curvature dependence......Lipid droplets play a central role in energy storage and metabolism on a cellular scale. Their core is comprised of hydrophobic lipids covered by a surface region consisting of amphiphilic lipids and proteins. For example, high and low density lipoproteins (HDL and LDL, respectively...

  15. Faraday forcing of high-temperature levitated liquid metal drops for the measurement of surface tension.

    Brosius, Nevin; Ward, Kevin; Matsumoto, Satoshi; SanSoucie, Michael; Narayanan, Ranga

    2018-01-01

    In this work, a method for the measurement of surface tension using continuous periodic forcing is presented. To reduce gravitational effects, samples are electrostatically levitated prior to forcing. The method, called Faraday forcing, is particularly well suited for fluids that require high temperature measurements such as liquid metals where conventional surface tension measurement methods are not possible. It offers distinct advantages over the conventional pulse-decay analysis method when the sample viscosity is high or the levitation feedback control system is noisy. In the current method, levitated drops are continuously translated about a mean position at a small, constant forcing amplitude over a range of frequencies. At a particular frequency in this range, the drop suddenly enters a state of resonance, which is confirmed by large executions of prolate/oblate deformations about the mean spherical shape. The arrival at this resonant condition is a signature that the parametric forcing frequency is equal to the drop's natural frequency, the latter being a known function of surface tension. A description of the experimental procedure is presented. A proof of concept is given using pure Zr and a Ti 39.5 Zr 39.5 Ni 21 alloy as examples. The results compare favorably with accepted literature values obtained using the pulse-decay method.

  16. Encouraging effects of a short-term, adapted Nordic diet intervention on skin microvascular function and skin oxygen tension in younger and older adults.

    Rogerson, David; McNeill, Scott; Könönen, Heidi; Klonizakis, Markos

    2018-05-01

    The microvascular benefits of regional diets appear in the literature; however, little is known about Nordic-type diets. We investigated the effects of a short-term, adapted, Nordic diet on microvascular function in younger and older individuals at rest and during activity. Thirteen young (mean age: 28 y; standard deviation: 5 y) and 15 older (mean age: 68 y; standard deviation: 6 y) participants consumed a modified Nordic diet for 4 wk. Laser Doppler flowmetry and transcutaneous oxygen monitoring were used to assess cutaneous microvascular function and oxygen tension pre- and postintervention; blood pressure, body mass, body fat percentage, ratings of perceived exertion, and peak heart rate during activity were examined concurrently. Axon-mediated vasodilation improved in older participants (1.17 [0.30] to 1.30 [0.30]; P Nordic diet might improve microvascular health. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Are macroinvertebrates in high altitude streams affected by oxygen deficiency?

    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...

  18. A hybrid multibreath wash-in wash-out lung function quantification scheme in human subjects using hyperpolarized 3 He MRI for simultaneous assessment of specific ventilation, alveolar oxygen tension, oxygen uptake, and air trapping.

    Hamedani, Hooman; Kadlecek, Stephen; Xin, Yi; Siddiqui, Sarmad; Gatens, Heather; Naji, Joseph; Ishii, Masaru; Cereda, Maurizio; Rossman, Milton; Rizi, Rahim

    2017-08-01

    To present a method for simultaneous acquisition of alveolar oxygen tension (P A O 2 ), specific ventilation (SV), and apparent diffusion coefficient (ADC) of hyperpolarized (HP) gas in the human lung, allowing reinterpretation of the P A O 2 and SV maps to produce a map of oxygen uptake (R). An imaging scheme was designed with a series of identical normoxic HP gas wash-in breaths to measure ADC, SV, P A O 2 , and R in less than 2 min. Signal dynamics were fit to an iterative recursive model that regionally solved for these parameters. This measurement was successfully performed in 12 subjects classified in three healthy, smoker, and chronic obstructive pulmonary disease (COPD) cohorts. The overall whole lung ADC, SV, P A O 2 , and R in healthy, smoker, and COPD subjects was 0.20 ± 0.03 cm 2 /s, 0.39 ± 0.06,113 ± 2 Torr, and 1.55 ± 0.35 Torr/s, respectively, in healthy subjects; 0.21 ± 0.03 cm 2 /s, 0.33 ± 0.06, 115.9 ± 4 Torr, and 0.97 ± 0.2 Torr/s, respectively, in smokers; and 0.25 ± 0.06 cm 2 /s, 0.23 ± 0.08, 114.8 ± 6.0Torr, and 0.94 ± 0.12 Torr/s, respectively, in subjects with COPD. Hetrogeneity of SV, P A O 2 , and R were indicators of both smoking-related changes and disease, and the severity of the disease correlated with the degree of this heterogeneity. Subjects with symptoms showed reduced oxygen uptake and specific ventilation. High-resolution, nearly coregistered and quantitative measures of lung function and structure were obtained with less than 1 L of HP gas. This hybrid multibreath technique produced measures of lung function that revealed clear differences among the cohorts and subjects and were confirmed by correlations with global lung measurements. Magn Reson Med 78:611-624, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  19. The state of emotional tension of tennis sportswomen-players of high qualification

    Uliz'ko V.M.

    2010-06-01

    Full Text Available An analysis and distributing of sportswomen is presented to on by the degree of expressed a personality and situation anxiety. 40 sportswomen took part in research. The psychophysiological functional state of man is studied in the conditions of high psychoemotional tension. The features of psychological mood are examined taking into account personality descriptions of every sportsman. Sporting achievement is the result of cooperation of external (financial, material and internal (attitude toward trainings, presence of genetic preconditions factors. External factors are mediated influence on success and cause for a sportsman the subjective states with the proper conduct.

  20. Formation and evolution of tweed structures on high-purity aluminum polycrystalline foils under cyclic tension

    Kuznetsov, P. V.; Vlasov, I. V.; Sklyarova, E. A.; Smekalina, T. V.

    2015-01-01

    Peculiarities of formation and evolution of tweed structures on the surface of high-purity aluminum polycrystalline foils under cyclic tension were studied using an atom force microscope and a white light interferometer. Tweed structures of micron and submicron sizes were found on the foils at different number of cycles. In the range of 42,000 < N < 95,000 cycles destruction of tweed patterns is observed, which leads to their disappearance from the surface of the foils. Formation of tweed structures of various scales is discussed in terms of the Grinfeld instability

  1. Influence of oxygen at high pressure on the induction of damage in barley seeds by gamma radiation

    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

  2. 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.

  3. High-tension electrical-arc-induced thermal burns caused by railway overhead cables.

    Koller, J

    1991-10-01

    Eleven patients with high-tension electrical-arc-induced thermal burns due to railway overhead cables were treated at the Bratislava Burn Department during a relatively short period of 18 months. All the injuries occurred by the same mechanism, that is persons climbing on top of railway carriages and approaching the 25,000 V a.c. overhead cables. All the burns were the result of an electrical arc passing externally to the body, with subsequent ignition of the victim's clothes. The cutaneous burns, ranging from 24 to 79 per cent of the BSA, were mostly deep partial to full skin thickness injuries. One patient died on day 5 postburn, the other survived. In spite of high-tension aetiology, no true electrical injuries appear to have occurred and no amputations were necessary. The pathophysiology and possible preventive measures are discussed. It must be stressed that arcing can be induced by an earthed object approaching, but not touching, a cable carrying a high voltage.

  4. 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.

  5. Modification of the radiation response of pig skin by manipulation of tissue oxygen tension using anesthetics and administration of BW12C

    van den Aardweg, G.J.; Hopewell, J.W.; Barnes, D.W.; Sansom, J.M.; Nethersell, A.B.

    1989-01-01

    The importance of tissue oxygen tension on radiosensitivity was studied by examining modifications in the incidence of moist desquamation in pig skin after irradiation with strontium-90 plaques. The effects were analyzed using quantal dose-response data and comparisons were made using ED50 values for moist desquamation. Under standard anesthetic conditions of 2% halothane, approximately 70% oxygen, and approximately 30% nitrous oxide, the ED50 value (+/- SE) for moist desquamation was 27.32 +/- 0.52 Gy with no significant variation in radiosensitivity between dorsal, lateral, and ventral skin sites on the flank. Irradiation with 2% halothane and air increased the ED50 to 31.25 +/- 0.94 Gy, primarily due to an increased radioresistance of the dorsal sites. When combined with BW12C, a drug which binds oxygen selectively to hemoglobin and hence reduced the oxygen availability to tissues, a further increase in the ED50 values was observed. This was approximately 39 Gy with BW12C concentrations of 30 mg/kg and 50 mg/kg b.w. of BW12C, indicating a dose modification factor (DMF) of approximately 1.26. However, when animals were breathing the standard gas mixture, this DMF was reduced to 1.15 for 30 mg/kg of BW12C, indicating that a higher level of oxygen partly counteracted the effects of the drug in these studies with BW12C. The greatest variability in radiosensitivity was seen in the dorsal fields. This suggested complex physiological adaptation, a phenomenon that might also explain the absence of any modification of the radiation response when 100 mg/kg of BW12C was used

  6. High-tension electricity network expansions in Argentina: decision mechanisms and willingness-to-pay revelation

    Chisari, O.O.; Dal-Bo, P.; Romero, C.A.

    2001-01-01

    This paper describes the procedures established by the present regulation for high-tension network expansions, studies its optimality and points its main problems. According to the present regulatory scheme, the decision to expand the high-tension network system is on the hands of the private sector. A simple model of the Argentine electricity system and its regulation allowed the simulation of cases in which the present 'Public Contest' method could result in the rejection of socially desirable projects and the acceptance of undesirable ones. Three main reasons for the existence of wrong incentives to investment are found. First, since consumers are not included in the mechanism, they have no way to reveal their willingness-to-pay for the investment. Second, the approximation of the future use of the line is done in such a way that it leaves important nodes under represented, thereby affecting the optimality of the mechanism. Third, the profit agents obtain from a line may not be related to their use, e.g. the generators profits depend also on generation costs

  7. High-tension electricity network expansions in Argentina: decision mechanisms and willingness-to-pay revelation

    Chisari, O.O. [Departamento de Economia y Finanzas, Universidad Argentina de la Empresa, Chile 1142 lo piso, 1073 Buenos Aires (Argentina); Dal-Bo, P. [Department of Economics, University of California, Los Angeles, CA (United States); Romero, C.A. [Departamento de Economia y Finanzas and Centro de Estudios Economicos de la Regulacion, Universidad Argentina de la Empresa, Buenos Aires (Argentina)

    2001-11-01

    This paper describes the procedures established by the present regulation for high-tension network expansions, studies its optimality and points its main problems. According to the present regulatory scheme, the decision to expand the high-tension network system is on the hands of the private sector. A simple model of the Argentine electricity system and its regulation allowed the simulation of cases in which the present 'Public Contest' method could result in the rejection of socially desirable projects and the acceptance of undesirable ones. Three main reasons for the existence of wrong incentives to investment are found. First, since consumers are not included in the mechanism, they have no way to reveal their willingness-to-pay for the investment. Second, the approximation of the future use of the line is done in such a way that it leaves important nodes under represented, thereby affecting the optimality of the mechanism. Third, the profit agents obtain from a line may not be related to their use, e.g. the generators profits depend also on generation costs.

  8. High-tension electrical injury to the heart as assessed by radionuclide imaging

    Iino, Hitoshi; Chikamori, Taishiro; Hatano, Tsuguhisa [Tokyo Medical Coll. (Japan)] [and others

    2002-12-01

    The purpose of this study was to evaluate cardiac complications associated with electrical injury, 7 patients with high-tension electrical injury (6,600 V alternating current) underwent {sup 201}Tl and {sup 123}I-metaiodobenzylguanidine (MIBG) imaging in addition to conventional electrocardiographic and echocardiographic assessments. Electrocardiography showed transient atrial fibrillation, second degree atrioventricular block, ST-segment depression, and sinus bradycardia in each patient. Echocardiography showed mild hypokinesis of the anterior wall in only 2 patients, but {sup 201}Tl and {sup 123}I-MIBG myocardial scintigraphy showed an abnormal scan image in 6/7 and 5/6 patients, respectively. Decreased radionuclide accumulation was seen primarily in areas extending from the anterior wall to the septum. Decreased radionuclide accumulation was smaller in extent and milder in degree in {sup 123}I-MIBG than in {sup 201}Tl imaging. These results suggest that even in patients without definite evidence of severe cardiac complications in conventional examinations, radionuclide imaging detects significant damage due to high-tension electrical injury, in which sympathetic nerve dysfunction might be milder than myocardial cell damage. (author)

  9. Tension Band Plating for Chronic Anterior Tibial Stress Fractures in High-Performance Athletes.

    Zbeda, Robert M; Sculco, Peter K; Urch, Ekaterina Y; Lazaro, Lionel E; Borens, Olivier; Williams, Riley J; Lorich, Dean G; Wellman, David S; Helfet, David L

    2015-07-01

    Anterior tibial stress fractures are associated with high rates of delayed union and nonunion, which can be particularly devastating to a professional athlete who requires rapid return to competition. Current surgical treatment strategies include intramedullary nailing, which has satisfactory rates of fracture union but an associated risk of anterior knee pain. Anterior tension band plating is a biomechanically sound alternative treatment for these fractures. Tension band plating of chronic anterior tibial stress fractures leads to rapid healing and return to physical activity and avoids the anterior knee pain associated with intramedullary nailing. Case series; Level of evidence, 4. Between 2001 and 2013, there were 13 chronic anterior tibial stress fractures in 12 professional or collegiate athletes who underwent tension band plating after failing nonoperative management. Patient charts were retrospectively reviewed for demographics, injury history, and surgical details. Radiographs were used to assess time to osseous union. Follow-up notes and phone interviews were used to determine follow-up time, return to training time, and whether the patient was able to return to competition. Cases included 13 stress fractures in 12 patients (9 females, 3 males). Five patients were track-and-field athletes, 4 patients played basketball, 2 patients played volleyball, and 1 was a ballet dancer. Five patients were Division I collegiate athletes and 7 were professional or Olympic athletes. Average age at time of surgery was 23.6 years (range, 20-32 years). Osseous union occurred on average at 9.6 weeks (range, 5.3-16.9 weeks) after surgery. Patients returned to training on average at 11.1 weeks (range, 5.7-20 weeks). Ninety-two percent (12/13) eventually returned to preinjury competition levels. Thirty-eight percent (5/13) underwent removal of hardware for plate prominence. There was no incidence of infection or nonunion. Anterior tension band plating for chronic tibial stress

  10. Oxygen diffusion in high-Tc superconductors

    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

  11. 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

  12. Anterior tibial stress fractures treated with anterior tension band plating in high-performance athletes.

    Cruz, Alexandre Santa; de Hollanda, João Paris Buarque; Duarte, Aires; Hungria Neto, José Soares

    2013-06-01

    The non-surgical treatment of anterior tibial cortex stress fractures requires long periods of abstention from sports activities and often results in non-union. Many different surgical techniques have already been previously described to treat these fractures, but there is no consensus on the best treatment. We describe the outcome of treatment using anterior tibial tension band plating in three high-performance athletes (4 legs) with anterior tibial cortex stress fractures. Tibial osteosynthesis with a 3.5-mm locking compression plate in the anterolateral aspect of the tibia was performed in all patients diagnosed with anterior tibial stress fracture after September 2010 at Santa Casa Hospital. All of the fractures were consolidated within a period of 3 months after surgery, allowing for an early return to pre-injury levels of competitive sports activity. There were no infection, non-union, malunion or anterior knee pain complications. Anterior tibial tension band plating leads to prompt fracture consolidation and is a good alternative for the treatment of anterior tibial cortex stress fractures. Bone grafts were shown to be unnecessary.

  13. Changes in the metabolic footprint of placental explant-conditioned medium cultured in different oxygen tensions from placentas of small for gestational age and normal pregnancies.

    Horgan, R P

    2012-01-31

    Being born small for gestational age (SGA) confers significantly increased risks of perinatal morbidity and mortality. Accumulating evidence suggests that an SGA fetus results from a poorly perfused and abnormally developed placenta. Some of the placental features seen in SGA, such as abnormal cell turnover and impaired nutrient transport, can be reproduced by culture of placental explants in hypoxic conditions. Metabolic footprinting offers a hypothesis-generating strategy to investigate factors absorbed by and released from this tissue in vitro. Previously, metabolic footprinting of the conditioned culture media has identified differences in placental explants cultured under normoxic and hypoxic conditions and between normal pregnancies and those complicated by pre-eclampsia. In this study we aimed to examine the differences in the metabolic footprint of placental villous explants cultured at different oxygen (O(2)) tensions between women who deliver an SGA baby (n = 9) and those from normal controls (n = 8). Placental villous explants from cases and controls were cultured for 96 h in 1% (hypoxic), 6% (normoxic) and 20% (hyperoxic) O(2). Metabolic footprints were analysed by Ultra Performance Liquid Chromatography coupled to an electrospray hybrid LTQ-Orbitrap Mass Spectrometry (UPLC-MS). 574 metabolite features showed significant difference between SGA and normal at one or more of the oxygen tensions. SGA explant media cultured under hypoxic conditions was observed, on a univariate level, to exhibit the same metabolic signature as controls cultured under normoxic conditions in 49% of the metabolites of interest, suggesting that SGA tissue is acclimatised to hypoxic conditions in vivo. No such behaviour was observed under hyperoxic culture conditions. Glycerophospholipid and tryptophan metabolism were highlighted as areas of particular interest.

  14. [Reduced muscular oxygen tension and nerve impulse transmission from antishock hose. Reduction of oxygen tension in the tibial muscle and impulse transmission in the peroneal nerve from pneumatic -1 pressure from antishock hose].

    Willy, C; Völker, H U; Weber, F; Albert, U; Sterk, J; Helm, M; Gerngross, H; Thomas, A

    1998-07-01

    The aim of the study was to assess, whether the pneumatic pressure of an antishock-trouser (AST) of 20-40 mm Hg induces a decreased oxygenation of the anterior tibial muscle and attenuates muscular response potential (MRP) of n. peronaeus profundus? Among 22 normotensive, healthy volunteers the AST were tested by applying pressure values between 0 and 100 mm Hg and measuring the intracompartmental pressure, the muscular oxygen pressure as well as the MRP by electroneurographic means within a period of 6 hours. The median initial intracompartmental pressure value of the m. tibialis anterior was 12.0 mm Hg (Q25%/Q75%: 8.9/17.3), the muscular oxygen pressure 14.8 mm Hg (Q25%/Q75%: 11.5/22.0). Transmission of the pneumatic AST-leg segment pressure to the muscle: 97.7% (Q25%/Q75%: 89.2/99.8). Already in the low AST pressure field (20-40 mm Hg) a severe hypoxia occurred in one case. A reduction of MRP was noticed at an AST pressure rate of 10 mm Hg. In 5 of 6 cases AST pressure values of 60 mm Hg led to pathological pO2-values within 5-20 minutes. Almost without exception AST-pressure rates < 60 mm Hg resulted in an anoxia of the muscle and loss of the MRP. We should demand that the AST are only applied with models where the pressure generated within the single segments can be controlled by pressure gauge. The application of the AST seems to be justified for polytraumatised in severe haemorrhagic shock where the risk of a local tissue ischemia with systemical consequences must deliberately be accepted.

  15. The development of the high-tension wire for nuclear fusion superconductive magnet measurement

    Yoshida, Kiyoshi; Morita, Yohsuke; Yamazaki, Takanori; Watanabe, Kiyoshi; Furusawa, Ken-ichi.

    1987-01-01

    Following on tokamak critical plasma testing device JT-60, experimental fusion reactor JT-100 is being developed. The 6 kV high-tension wire has been developed for use in JT-100 under ultra-low temperature and high radiation environment. Used for superconductive magnet measurement, the wire is inserted in the vacuum vessel, being immersed within the liquid helium. As the insulating material of this wire, polyetherimido was found to be most suitable in the respects of radiation resistance and voltage-withstand property. In an electric wire covered with polyetherimido, which was made in trial, its test in voltage-withstand and bending characteristics at ultra-low temperature showed the wire to be usable for the intended purpose. (Mori, K.)

  16. The insulation condition diagnosis of high tension generator stators; Diagnostico del estado de aislamiento de estatores de generadores de alta tension

    Robles Pimentel, Edgar Guillermo; Rosales Sedano, Inocente [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1990-12-31

    The high tension electrical generators are very high cost equipment, therefore they need to be very reliable. The generators preventive maintenance based in diagnosis techniques of the insulation condition might mean substantial savings for the user. In this article the most common techniques employed all over the world are presented, the greatest part of them already implemented in Mexico by the authors. The techniques and the equipment employed are analyzed and are exemplified with the results obtained in some field experiences. [Espanol] Los generadores electricos de alta tension son equipos de muy alto costo, por lo que necesitan ser muy confiables. El mantenimiento preventivo de los generadores basado en tecnicas de diagnostico del estado del aislamiento puede significar ahorros sustanciales al usuario. En este articulo se presentan las tecnicas mas comunes empleadas en el mundo, la mayor parte de ellas ya implantadas en Mexico por los autores. Se analizan las tecnicas y el equipo empleado, y se ejemplifica con resultados obtenidos de algunas de las experiencias en el campo.

  17. The insulation condition diagnosis of high tension generator stators; Diagnostico del estado de aislamiento de estatores de generadores de alta tension

    Robles Pimentel, Edgar Guillermo; Rosales Sedano, Inocente [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1989-12-31

    The high tension electrical generators are very high cost equipment, therefore they need to be very reliable. The generators preventive maintenance based in diagnosis techniques of the insulation condition might mean substantial savings for the user. In this article the most common techniques employed all over the world are presented, the greatest part of them already implemented in Mexico by the authors. The techniques and the equipment employed are analyzed and are exemplified with the results obtained in some field experiences. [Espanol] Los generadores electricos de alta tension son equipos de muy alto costo, por lo que necesitan ser muy confiables. El mantenimiento preventivo de los generadores basado en tecnicas de diagnostico del estado del aislamiento puede significar ahorros sustanciales al usuario. En este articulo se presentan las tecnicas mas comunes empleadas en el mundo, la mayor parte de ellas ya implantadas en Mexico por los autores. Se analizan las tecnicas y el equipo empleado, y se ejemplifica con resultados obtenidos de algunas de las experiencias en el campo.

  18. 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

  19. Oxygen Handling and Cooling Options in High Temperature Electrolysis Plants

    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

  20. Solving the tension between high-scale inflation and axion isocurvature perturbations

    Higaki, Tetsutaro; Takahashi, Fuminobu; Tokyo Univ., Kashiwa

    2014-03-01

    The BICEP2 experiment determined the Hubble parameter during inflation to be about 10 14 GeV. Such high inflation scale is in tension with the QCD axion dark matter if the Peccei-Quinn (PQ) symmetry remains broken during and after inflation, because too large axion isocurvature perturbations would be generated. The axion isocurvature perturbations can be suppressed if the axion acquires a sufficiently heavy mass during inflation. We show that this is realized if the PQ symmetry is explicitly broken down to a discrete symmetry and if the breaking is enhanced during inflation. We also show that, even when the PQ symmetry becomes spontaneously broken after inflation, such a temporarily enhanced PQ symmetry breaking relaxes the constraint on the axion decay constant.

  1. Surface tension-induced high aspect-ratio PDMS micropillars with concave and convex lens tips

    Li, Huawei

    2013-04-01

    This paper reports a novel method for the fabrication of 3-dimensional (3D) Polydimethylsiloxane (PDMS) micropillars with concave and convex lens tips in a one-step molding process, using a CO2 laser-machined Poly(methyl methacrylate) (PMMA) mold with through holes. The PDMS micropillars are 4 mm high and have an aspect ratio of 251. The micropillars are formed by capillary force drawing up PDMS into the through hole mold. The concave and convex lens tips of the PDMS cylindrical micropillars are induced by surface tension and are controllable by changing the surface wetting properties of the through holes in the PMMA mold. This technique eliminates the requirements of expensive and complicated facilities to prepare a 3D mold, and it provides a simple and rapid method to fabricate 3D PDMS micropillars with controllable dimensions and tip shapes. © 2013 IEEE.

  2. Surface tension-induced high aspect-ratio PDMS micropillars with concave and convex lens tips

    Li, Huawei; Fan, Yiqiang; Yi, Ying; Foulds, Ian G.

    2013-01-01

    This paper reports a novel method for the fabrication of 3-dimensional (3D) Polydimethylsiloxane (PDMS) micropillars with concave and convex lens tips in a one-step molding process, using a CO2 laser-machined Poly(methyl methacrylate) (PMMA) mold with through holes. The PDMS micropillars are 4 mm high and have an aspect ratio of 251. The micropillars are formed by capillary force drawing up PDMS into the through hole mold. The concave and convex lens tips of the PDMS cylindrical micropillars are induced by surface tension and are controllable by changing the surface wetting properties of the through holes in the PMMA mold. This technique eliminates the requirements of expensive and complicated facilities to prepare a 3D mold, and it provides a simple and rapid method to fabricate 3D PDMS micropillars with controllable dimensions and tip shapes. © 2013 IEEE.

  3. Dynamic high-temperature characterization of an iridium alloy in tension

    Song, Bo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nelson, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Jin, Helena [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bignell, John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); George, E. P. [Ruhr Univ., Bochum (Germany)

    2015-09-01

    Iridium alloys have been utilized as structural materials for certain high-temperature applications, due to their superior strength and ductility at elevated temperatures. The mechanical properties, including failure response at high strain rates and elevated temperatures of the iridium alloys need to be characterized to better understand high-speed impacts at elevated temperatures. A DOP-26 iridium alloy has been dynamically characterized in compression at elevated temperatures with high-temperature Kolsky compression bar techniques. However, the dynamic high-temperature compression tests were not able to provide sufficient dynamic high-temperature failure information of the iridium alloy. In this study, we modified current room-temperature Kolsky tension bar techniques for obtaining dynamic tensile stress-strain curves of the DOP-26 iridium alloy at two different strain rates (~1000 and ~3000 s-1) and temperatures (~750°C and ~1030°C). The effects of strain rate and temperature on the tensile stress-strain response of the iridium alloy were determined. The DOP-26 iridium alloy exhibited high ductility in stress-strain response that strongly depended on both strain rate and temperature.

  4. Vacuum ultraviolet spectra from highly ionized oxygen

    Sjoedin, R.; Pihl, J.; Hallin, R.; Lindskog, J.; Marelius, A.; Sharma, K.

    1976-03-01

    Transitions in Li-like, He-like and H-like oxygen have been observed in the wavelength region 350-1150 A. A number of lines assigned as transitions in the doubly excited quartet system of O VI are reported. Lifetimes for the 4f 3 F term in O VII, 4f 2 F, 4d 2 D, 4p 2 P terms and for the 2s4f 4 F term in O VI have been measured to 13+-6 ps, 48+-3 ps, 29+-4 ps, 73+-8 ps and 47+-4 ps respectively. (Auth.)

  5. Cellular and molecular repair of X-ray-induced damage: dependence on oxygen tension and nutritional status

    Spiro, I.J.; Kennedy, K.A.; Stickler, R.; Ling, C.C.

    1985-01-01

    Cellular and molecular repair was studied at 23 0 C using split-dose recovery and alkaline elution techniques, respectively, as a function of cellular oxygen and nutrient conditions. Hypoxic cells in full medium showed a partial reduction in the level of sublethal damage (SLD) repair relative to aerated cells; the respective repair kinetics were similar with a common repair half-time of 30 min. Similarly, hypoxic cells showed a slight reduction in strand break rejoining capacity compared to aerated cells. Under nutrient deprivation, anoxic cells displayed no SLD repair or strand break repair, while aerated cells exhibited the same level of SLD and strand break repair as for well-fed cells. In addition, nutrient deprived cells at low O 2 levels displayed normal SLD and strand break repair capability. These results indicate that both nutrient and O 2 deprivation are necessary for complete inhibition of cellular and molecular repair, and low levels of O 2 can effectively reverse this inhibition

  6. Tension Headache

    ... tight band around your head. A tension headache (tension-type headache) is the most common type of headache, and ... Headache after a head injury, especially if the headache gets worse ... tension or stress. But research suggests muscle contraction isn't the ...

  7. Artificial intelligence tools to support the analysis of the high tension insulator flaming; Herramientas de inteligencia artificial de apoyo al analisis de flameos en aisladores de alta tension

    Rodriguez Ortiz, Guillermo; Mejia Lavalle, Manuel; Montoya Tena, Gerardo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1996-12-31

    Four artificial intelligence tools developed at the Instituto de Investigaciones Electricas (IIE) to support the analysis of high tension insulator flaming are described. The first tool builds up a decision tree departing from historical data, the other 3 tools operate departing from the decision tree previously created to generate production rules, function as an expert system and make tests with many already known cases. These tools could predict the impending occurrence of flaming with enough time allowance for the insulators to be cleaned, since the traditional practice is the periodical cleaning of the insulators and this is not always adequate since the cleaning teams are limited, and the action of the environment is not always constant and for that reason insulators that do not need it are cleaned and vice-versa [Espanol] Se describen 4 herramientas de inteligencia artificial desarrolladas en el Instituto de Investigaciones Electricas (IIE) para apoyar al analisis de flameos en aisladores de alta tension. La primera herramienta construye el arbol de decision a partir de datos historicos; las otras 3 herramientas operan a partir del arbol de decision previamente creado para generar reglas de produccion, funcionar a la manera de un sistema experto y hacer pruebas con muchos casos conocidos. Estas herramientas podrian predecir la ocurrencia inminente del flameo con tiempo suficiente para que los aisladores se limpien, ya que la forma tradicional es limpiar periodicamente los aisladores y esto a veces no es adecuado debido a que las cuadrillas de limpieza son limitadas, ademas de que la accion del medio ambiente no es constante y es por eso que a veces se limpian aisladores que no lo necesitan o viceversa

  8. Artificial intelligence tools to support the analysis of the high tension insulator flaming; Herramientas de inteligencia artificial de apoyo al analisis de flameos en aisladores de alta tension

    Rodriguez Ortiz, Guillermo; Mejia Lavalle, Manuel; Montoya Tena, Gerardo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1997-12-31

    Four artificial intelligence tools developed at the Instituto de Investigaciones Electricas (IIE) to support the analysis of high tension insulator flaming are described. The first tool builds up a decision tree departing from historical data, the other 3 tools operate departing from the decision tree previously created to generate production rules, function as an expert system and make tests with many already known cases. These tools could predict the impending occurrence of flaming with enough time allowance for the insulators to be cleaned, since the traditional practice is the periodical cleaning of the insulators and this is not always adequate since the cleaning teams are limited, and the action of the environment is not always constant and for that reason insulators that do not need it are cleaned and vice-versa [Espanol] Se describen 4 herramientas de inteligencia artificial desarrolladas en el Instituto de Investigaciones Electricas (IIE) para apoyar al analisis de flameos en aisladores de alta tension. La primera herramienta construye el arbol de decision a partir de datos historicos; las otras 3 herramientas operan a partir del arbol de decision previamente creado para generar reglas de produccion, funcionar a la manera de un sistema experto y hacer pruebas con muchos casos conocidos. Estas herramientas podrian predecir la ocurrencia inminente del flameo con tiempo suficiente para que los aisladores se limpien, ya que la forma tradicional es limpiar periodicamente los aisladores y esto a veces no es adecuado debido a que las cuadrillas de limpieza son limitadas, ademas de que la accion del medio ambiente no es constante y es por eso que a veces se limpian aisladores que no lo necesitan o viceversa

  9. 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...

  10. 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.

  11. Effects of in vitro low oxygen tension preconditioning of adipose stromal cells on their in vivo chondrogenic potential: application in cartilage tissue repair.

    Sophie Portron

    Full Text Available PURPOSE: Multipotent stromal cell (MSC-based regenerative strategy has shown promise for the repair of cartilage, an avascular tissue in which cells experience hypoxia. Hypoxia is known to promote the early chondrogenic differentiation of MSC. The aim of our study was therefore to determine whether low oxygen tension could be used to enhance the regenerative potential of MSC for cartilage repair. METHODS: MSC from rabbit or human adipose stromal cells (ASC were preconditioned in vitro in control or chondrogenic (ITS and TGF-β medium and in 21 or 5% O2. Chondrogenic commitment was monitored by measuring COL2A1 and ACAN expression (real-time PCR. Preconditioned rabbit and human ASC were then incorporated into an Si-HPMC hydrogel and injected (i into rabbit articular cartilage defects for 18 weeks or (ii subcutaneously into nude mice for five weeks. The newly formed tissue was qualitatively and quantitatively evaluated by cartilage-specific immunohistological staining and scoring. The phenotype of ASC cultured in a monolayer or within Si-HPMC in control or chondrogenic medium and in 21 or 5% O2 was finally evaluated using real-time PCR. RESULTS/CONCLUSIONS: 5% O2 increased the in vitro expression of chondrogenic markers in ASC cultured in induction medium. Cells implanted within Si-HPMC hydrogel and preconditioned in chondrogenic medium formed a cartilaginous tissue, regardless of the level of oxygen. In addition, the 3D in vitro culture of ASC within Si-HPMC hydrogel was found to reinforce the pro-chondrogenic effects of the induction medium and 5% O2. These data together indicate that although 5% O2 enhances the in vitro chondrogenic differentiation of ASC, it does not enhance their in vivo chondrogenesis. These results also highlight the in vivo chondrogenic potential of ASC and their potential value in cartilage repair.

  12. Inverse Regulation of Early and Late Chondrogenic Differentiation by Oxygen Tension Provides Cues for Stem Cell-Based Cartilage Tissue Engineering

    Sophie Portron

    2015-01-01

    Full Text Available Background/Aims: Multipotent stem/stromal cells (MSC are considered promising for cartilage tissue engineering. However, chondrogenic differentiation of MSC can ultimately lead to the formation of hypertrophic chondrocytes responsible for the calcification of cartilage. To prevent the production of this calcified matrix at the articular site, the late hypertrophic differentiation of MSCs must be carefully controlled. Given that articular cartilage is avascular, we hypothesized that in addition to its stimulatory role in the early differentiation of chondrogenic cells, hypoxia may prevent their late hypertrophic conversion. Methods: Early and late chondrogenic differentiation were evaluated using human adipose MSC and murine ATDC5 cells cultured under either normoxic (21%O2 or hypoxic (5%O2 conditions. To investigate the effect of hypoxia on late chondrogenic differentiation, the transcriptional activity of hypoxia-inducible factor-1alpha (HIF-1α and HIF-2α were evaluated using the NoShift DNA-binding assay and through modulation of their activity (chemical inhibitor, RNA interference. Results: Our data demonstrate that low oxygen tension not only stimulates the early chondrogenic commitment of two complementary models of chondrogenic cells, but also inhibits their hypertrophic differentiation. Conclusion: These results suggest that hypoxia can be used as an instrumental tool to prevent the formation of a calcified matrix in MSC-based cartilage tissue engineering.

  13. End-Tidal CO2 Tension Is Predictive of Effective Nocturnal Oxygen Therapy in Patients with Chronic Heart Failure and Central Sleep Apnea.

    Sugimura, Koichiro; Shinozaki, Tsuyoshi; Fukui, Shigefumi; Ogawa, Hiromasa; Shimokawa, Hiroaki

    2016-05-01

    Central sleep apnea (CSA) is characterized by recurring cycles of crescendo-decrescendo ventilation during sleep, and enhances sympathetic nerve activity. Thus CSA has a prognostic impact in patients with chronic heart failure (CHF). Although nocturnal oxygen (O2) therapy decreases frequency of CSA and improves functional exercise capacity, it is also known that some non-responders to the therapy exist. We thus aimed to identify predictors of responders to nocturnal O2 therapy in CHF patients with CSA. In 12 CHF patients with CSA hospitalized at our department, sleep study was performed at 2 consecutive nights. Patients nasally inhaled O2 at either the first or second night in a randomized manner. To predict the percentage reduction in apnea-hypopnea index (%ΔAHI) in response to the nocturnal O2 therapy, we performed multiple regression analysis with a stepwise method with variables including age, brain-natriuretic peptide, circulation time, baseline AHI, hypercapnic ventilatory response and end-tidal carbon dioxide tension (PETCO2). Nocturnal O2 therapy significantly decreased AHI (from 32 ± 13 /h to 12 ± 10 /h, P 50% reduction of AHI), with 88.9% of sensitivity and 66.7% of specificity. In conclusion, PETCO2 is useful to predict the efficacy of O2 therapy in CHF patients with CSA, providing important information to the current nocturnal O2 therapy.

  14. Breakdown of highly excited oxygen in a DC electric field

    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

  15. Sitting and standing postures are corrected by adjustable furniture with lowered muscle tension in high-school students.

    Koskelo, R; Vuorikari, K; Hänninen, O

    2007-10-01

    This study compared the effect of 24 months of adjustable school desks and chairs usage (the intervention) and traditional non-adjustable usage (the control condition) on sitting and standing postures, muscle strength, classroom muscle tension, pain and learning in 15 (8 female and 7 male) high-school students and 15 anthropometrically and gender matched control students from neighbouring schools. It was assessed whether any responses took place after growth cessation. In comparison with controls, the intervention group of students' sitting postures standing kyphosis, scoliosis and lordosis became significantly better, both before and after growth cessation. Trunk muscle strength increased in the intervention students whose muscle tension during classes fell significantly in the trapezius and lumbar muscles, whereas in control students' lumbar tension increased. Headache and low-back pain correlated with neck-shoulder pain and trapezius muscle tension. Intervention students reported that they experienced benefits from the adjustable tables and chairs. They also received significantly better overall marks than the controls at the end of high school. It is concluded that the adjustable school desks and chairs promoted better sitting and standing postures, increased muscle strength, alleviated pain and appeared to be associated with better overall academic marks.

  16. Surface tension estimation of high temperature melts of the binary alloys Ag-Au

    Dogan, Ali; Arslan, Hüseyin

    2017-11-01

    Surface tension calculation of the binary alloys Ag-Au at the temperature of 1381 K, where Ag and Au have similar electronic structures and their atomic radii are comparable, are carried out in this study using several equations over entire composition range of Au. Apparently, the deviations from ideality of the bulk solutions, such as activities of Ag and Au are small and the maximum excess Gibbs free energy of mixing of the liquid phase is for instance -4500 J/mol at XAu = 0.5. Besides, the results obtained in Ag-Au alloys that at a constant temperature the surface tension increases with increasing composition while the surface tension decreases as the temperature increases for entire composition range of Au. Although data about surface tension of the Ag-Au alloy are limited, it was possible to make a comparison for the calculated results for the surface tension in this study with the available experimental data. Taken together, the average standard error analysis that especially the improved Guggenheim model in the other models gives the best agreement along with the experimental results at temperature 1383 K although almost all models are mutually in agreement with the other one.

  17. High rate response of ultra-high-performance fiber-reinforced concretes under direct tension

    Tran, Ngoc Thanh [Department of Civil and Environmental Engineering, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of); Tran, Tuan Kiet [Department of Civil and Environmental Engineering, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of); Department of Civil Engineering and Applied Mechanics, Ho Chi Minh City University of Technology and Education, 01 Vo Van Ngan, Thu Duc District, Ho Chi Minh City (Viet Nam); Kim, Dong Joo, E-mail: djkim75@sejong.ac.kr [Department of Civil and Environmental Engineering, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of)

    2015-03-15

    The tensile response of ultra-high-performance fiber-reinforced concretes (UHPFRCs) at high strain rates (5–24 s{sup −} {sup 1}) was investigated. Three types of steel fibers, including twisted, long and short smooth steel fibers, were added by 1.5% volume content in an ultra high performance concrete (UHPC) with a compressive strength of 180 MPa. Two different cross sections, 25 × 25 and 25 × 50 mm{sup 2}, of tensile specimens were used to investigate the effect of the cross section area on the measured tensile response of UHPFRCs. Although all the three fibers generated strain hardening behavior even at high strain rates, long smooth fibers produced the highest tensile resistance at high rates whereas twisted fiber did at static rate. The breakages of twisted fibers were observed from the specimens tested at high strain rates unlike smooth steel fibers. The tensile behavior of UHPFRCs at high strain rates was clearly influenced by the specimen size, especially in post-cracking strength.

  18. Swimming performance, venous oxygen tension and cardiac performance of coronary-ligated rainbow trout, Oncorhynchus mykiss, exposed to progressive hypoxia

    Steffensen, J F; Farrell, A P

    1998-01-01

    We performed in vivo studies to examine the idea that cardiac work is impaired in rainbow trout (Oncorhynchus mykiss) below a certain venous PO2 threshold. We hypothesized that coronary-ligated fish, swimming continuously at a reasonably high water velocity (1.5 body lengths x s(-1)) and exposed...... to progressive hypoxia, would fatigue at higher venous PO2 and ambient water PO2 compared with sham-operated fish. However, we found that both the lowest venous PO2 that supported hypoxic swimming (9.9 torr for coronary-ligated fish and 11.1 torr for sham-operated fish) and the venous PO2 at fatigue (7.8 torr...... and 8.6 torr, respectively) were the same for coronary-ligated and sham-operated fish. Also, both groups quit swimming at the same water PO2 heart rate and hematocrit. Nevertheless, significant differences in cardiac performance did exist between the two groups. Whereas ventral aortic blood pressure...

  19. 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.

  20. Oxygenation of the traditional and thin-walled MT-YBCO in flowing oxygen and under high evaluated oxygen pressure

    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

  1. Superiority of Transcutaneous Oxygen Tension Measurements in Predicting Limb Salvage After Below-the-Knee Angioplasty: A Prospective Trial in Diabetic Patients With Critical Limb Ischemia

    Redlich, Ulf; Xiong, Yan Y.; Pech, Maciej; Tautenhahn, Jörg; Halloul, Zuhir; Lobmann, Ralf; Adolf, Daniela; Ricke, Jens; Dudeck, Oliver

    2011-01-01

    Purpose: To assess postprocedural angiograms, the ankle–brachial index (ABI), and transcutaneous oxygen tension (TcPO 2 ) to predict outcome after infrageniculate angioplasty (PTA) in diabetic patients with critical limb ischemia (CLI) scheduled for amputation. Materials and Methods: PTA was performed in 28 diabetic patients with CLI confined to infrapopliteal vessels. We recorded patency of crural vessels, including the vascular supply of the foot as well as the ABI and TcPO 2 of the foot. Results: Technical success rate was 92.9% (n = 26), and limb-salvage rate at 12 months was 60.7% (n = 17). The number of patent straight vessels above and below the level of the malleoli increased significantly in patients avoiding amputation. Amputation was unnecessary in 88.2% (n = 15) patients when patency of at least one tibial artery was achieved. In 72.7% (n = 8) of patients, patency of the peroneal artery alone was not sufficient for limb salvage. ABI was of no predictive value for limb salvage. TcPO 2 values increased significantly only in patients not requiring amputation (P = 0.015). In patients with only one tibial artery supplying the foot or only a patent peroneal artery in postprocedural angiograms, TcPO 2 was capable of reliably predicting the outcome. Conclusion: Below-the-knee PTA as an isolated part of therapy was effective to prevent major amputation in more than a half of diabetic patients with CLI. TcPO 2 was a valid predictor for limb salvage, even when angiographic outcome criteria failed.

  2. Transcriptional and metabolic response of recombinant Escherichia coli to spatial dissolved oxygen tension gradients simulated in a scale-down system.

    Lara, Alvaro R; Leal, Lidia; Flores, Noemí; Gosset, Guillermo; Bolívar, Francisco; Ramírez, Octavio T

    2006-02-05

    Escherichia coli, expressing recombinant green fluorescent protein (GFP), was subjected to dissolved oxygen tension (DOT) oscillations in a two-compartment system for simulating gradients that can occur in large-scale bioreactors. Cells were continuously circulated between the anaerobic (0% DOT) and aerobic (10% DOT) vessels of the scale-down system to mimic an overall circulation time of 50 s, and a mean residence time in the anaerobic and aerobic compartments of 33 and 17 s, respectively. Transcription levels of mixed acid fermentation genes (ldhA, poxB, frdD, ackA, adhE, pflD, and fdhF), measured by quantitative RT-PCR, increased between 1.5- to over 6-fold under oscillatory DOT compared to aerobic cultures (constant 10% DOT). In addition, the transcription level of fumB increased whereas it decreased for sucA and sucB, suggesting that the tricarboxylic acid cycle was functioning as two open branches. Gene transcription levels revealed that cytrochrome bd, which has higher affinity to oxygen but lower energy efficiency, was preferred over cytochrome bO3 in oscillatory DOT cultures. Post-transcriptional processing limited heterologous protein production in the scale-down system, as inferred from similar gfp transcription but 19% lower GFP concentration compared to aerobic cultures. Simulated DOT gradients also affected the transcription of genes of the glyoxylate shunt (aceA), of global regulators of aerobic and anaerobic metabolism (fnr, arcA, and arcB), and other relevant genes (luxS, sodA, fumA, and sdhB). Transcriptional changes explained the observed alterations in overall stoichiometric and kinetic parameters, and production of ethanol and organic acids. Differences in transcription levels between aerobic and anaerobic compartments were also observed, indicating that E. coli can respond very fast to intermittent DOT conditions. The transcriptional responses of E. coli to DOT gradients reported here are useful for establishing rational scale-up criteria and

  3. 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).

  4. Introduction of high oxygen concentrations into silicon wafers by high-temperature diffusion

    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

  5. Oxygen stoichiometry and the high Tc superconducting oxides

    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

  6. Autoionizing states in highly ionized oxygen, fluorine and silicon

    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

  7. Abnormal pain processing in chronic tension-type headache: a high-density EEG brain mapping study

    Buchgreitz, L.; Egsgaard, L.L.; Jensen, R.

    2008-01-01

    Central sensitization caused by prolonged nociceptive input from muscles is considered to play an important role for chronification of tension-type headache. In the present study we used a new high-density EEG brain mapping technique to investigate spatiotemporal aspects of brain activity...... in response to muscle pain in 19 patients with chronic tension-type headache (CTTH) and 19 healthy, age- and sex-matched controls. Intramuscular electrical stimuli (single and train of five pulses delivered at 2 Hz) were applied to the trapezius muscle and somatosensory evoked potentials were recorded...... with 128-channel EEG both in- and outside a condition with induced tonic neck/shoulder muscle pain (glutamate injection into the trapezius muscle). Significant reduction in magnitude during and after induced tonic muscle pain was found in controls at the P200 dipole in response to both the first (baseline...

  8. 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.

  9. Optimal Cable Tension Distribution of the High-Speed Redundant Driven Camera Robots Considering Cable Sag and Inertia Effects

    Yu Su

    2014-03-01

    Full Text Available Camera robots are high-speed redundantly cable-driven parallel manipulators that realize the aerial panoramic photographing. When long-span cables and high maneuverability are involved, the effects of cable sags and inertias on the dynamics must be carefully dealt with. This paper is devoted to the optimal cable tension distribution (OCTD for short of the camera robots. Firstly, each fast varying-length cable is discretized into some nodes for computing the cable inertias. Secondly, the dynamic equation integrated with the cable inertias is set up regarding the large-span cables as catenaries. Thirdly, an iterative optimization algorithm is introduced for the cable tension distribution by using the dynamic equation and sag-to-span ratios as constraint conditions. Finally, numerical examples are presented to demonstrate the effects of cable sags and inertias on determining tensions. The results justify the convergence and effectiveness of the algorithm. In addition, the results show that it is necessary to take the cable sags and inertias into consideration for the large-span manipulators.

  10. High-temperature reaction of ''anisotropic'' pyrolitic graphite with oxygen

    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

  11. Oxygenation of the traditional and thin-walled MT-YBCO in flowing oxygen and under high evaluated oxygen pressure

    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.

  12. 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.

  13. High temperature properties of Zircaloy--oxygen alloys

    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

  14. Tension headache.

    Ziegler, D K

    1978-05-01

    Headache is an extremely common symptom, and many headaches undoubtedly have a relationship to stressful situations. The clear definition, however, of a "tension headache" complex and its differentiation from migraine in some patients is difficult. The problems are in the identification of a specific headache pattern induced by stress or "tension" and the relationship of the symptom to involuntary contraction of neck and scalp muscles. Treatment consists of analgesics and occasionally mild tranquilizers. Psychotherapy consists of reassurance and often other supportive measures, including modification of life styles. Various feedback techniques have been reported of value, but their superiority to suggestion and hypnosis is still problematic.

  15. 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...

  16. 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.

  17. 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.

  18. High temperature expansions for the free energy of vortices respectively the string tension in lattice gauge theories

    Muenster, G.

    1980-05-01

    We derive high temperature cluster expansions for the free energy of vortices in SU(2) and Z 2 lattice gauge theories in 3 and 4 dimensions. The expected behaviour of the vortex free energy is verified. It obeys an area law behaviour. The coefficient of the area is shown to be equal to the string tension between static quarks. We calculate its expansion up to 12th order. For SU(2) in 4 dimensions the result is compared with Monte Carlo calculations of Creutz and is in good agreement at strong and intermediate coupling. (orig.)

  19. L-lysine escinat, thiotriazolin, gordox and mydocalm influence on oxygen tension in the intestinal wall and acid-base balance and limited proteolysis in intestinal venous blood in terms of intraabdominal hypertension modeling

    Sapegin V.I.

    2014-11-01

    Full Text Available In acute experiments on rabbits there were studied changes in oxygen tension in the intestinal wall tissues, acid-base balance and limited proteolysis and its inhibitors in intestinal venous blood, protective action of L-lysine escinat (0,15 mg/kg / single dose, thiotriazolin (25 mg/kg / single dose, aprotinin (gordox (10,000 units/kg / single dose in sequential modeling of standard levels increasing of intra-abdominal hypertension (IAH — 50, 100, 150, 200, 250, 300, 350 m H2O, and also of tolperison (mydocalm (5 mg/kg / single dose on modeling of stable 3-hour IAH 200 m H2O. The IAH modeling was performed by means of stand of our construction. Under the influence of IAH the compensated metabolic acidosis in intestinal venous blood with a compensative hyperpnoe develops, decline of oxygen tension in tissues and activating of a limited proteolysis as well as decline of its inhibitors activity in intestinal venous blood occur. By the degree of metabolic acidosis prevention investigational preparations were distributed as follows gordox > thiotriazolin = L-lysine escinat = mydocalm, and by prevention of decline of oxygen tension in tissues — thiotriazolin > L-lysine escinat > mydocalm > gordox, it is is connected with different rate of methabolic products excretion into the blood, due to the influence on blood circulation and transcapilary exchange. By the degree of prevention of proteolytic activity and inhibitory potential changes, investigational preparations were distributed as follows: gordox > mydocalm > thiotriazolin > L-lysine escinat, this is connected with inhibition of proteolysis in gordox, and in other ones – with reduction of ischemic damage of tissues. Owing to different mechanism of action thiotriazolin, L-lysine escinat and mydocalm may be simultaneously recommended for a conservative treatment of patients with intraabdominal hypertension syndrome.

  20. Intra-operative tissue oxygen tension is increased by local insufflation of humidified-warm CO2 during open abdominal surgery in a rat model.

    Jean K Marshall

    Full Text Available Maintenance of high tissue oxygenation (PtO2 is recommended during surgery because PtO2 is highly predictive of surgical site infection and colonic anastomotic leakage. However, surgical site perfusion is often sub-optimal, creating an obstructive hurdle for traditional, systemically applied therapies to maintain or increase surgical site PtO2. This research tested the hypothesis that insufflation of humidified-warm CO2 into the abdominal cavity would increase sub-peritoneal PtO2 during open abdominal surgery.15 Wistar rats underwent laparotomy under general anesthesia. Three sets of randomized cross-over experiments were conducted in which the abdominal cavity was subjected to alternating exposure to 1 humidified-warm CO2 & ambient air; 2 humidified-warm CO2 & dry-cold CO2; and 3 dry-cold CO2 & ambient air. Sub-peritoneal PtO2 and tissue temperature were measured with a polarographic oxygen probe.Upon insufflation of humidified-warm CO2, PtO2 increased by 29.8 mmHg (SD 13.3; p<0.001, or 96.6% (SD 51.9, and tissue temperature by 3.0°C (SD 1.7 p<0.001, in comparison with exposure to ambient air. Smaller, but significant, increases in PtO2 were seen in experiments 2 and 3. Tissue temperature decreased upon exposure to dry-cold CO2 compared with ambient air (-1.4°C, SD 0.5, p = 0.001.In a rat model, insufflation of humidified-warm CO2 into the abdominal cavity during open abdominal surgery causes an immediate and potentially clinically significant increase in PtO2. The effect is an additive result of the delivery of CO2 and avoidance of evaporative cooling via the delivery of the CO2 gas humidified at body temperature.

  1. Uncovering behavioural diversity amongst high-strength Pseudomonas spp. surfactants at the limit of liquid surface tension reduction.

    Kabir, Kamaluddeen; Deeni, Yusuf Y; Hapca, Simona M; Moore, Luke; Spiers, Andrew J

    2018-02-01

    Bacterial biosurfactants have a wide range of biological functions and biotechnological applications. Previous analyses had suggested a limit to their reduction of aqueous liquid surface tensions (γMin), and here we confirm this in an analysis of 25 Pseudomonas spp. strains isolated from soil which produce high-strength surfactants that reduce surface tensions to 25.2 ± 0.1-26.5 ± 0.2 mN m-1 (the surface tension of sterile growth medium and pure water was 52.9 ± 0.4 mN m-1 and 72.1 ± 1.2 mN m-1, respectively). Comparisons of culture supernatants produced using different growth media and semi-purified samples indicate that the limit of 24.2-24.7 mN m-1 is not greatly influenced by culture conditions, pH or NaCl concentrations. We have used foam, emulsion and oil-displacement behavioural assays as a simple and cost-effective proxy for in-depth biochemical characterisation, and these suggest that there is significant structural diversity amongst these surfactants that may reflect different biological functions and offer new biotechnological opportunities. Finally, we obtained a draft genome for the strain producing the highest strength surfactant, and identified a cluster of non-ribosomal protein synthase genes that may produce a cyclic lipopeptide (CLP)-like surfactant. Further investigation of this group of related bacteria recovered from the same site will allow a better understanding of the significance of the great variety of surfactants produced by bacterial communities found in soil and elsewhere. © FEMS 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. High temperature microcalorimetry. Study of metal-oxygen systems

    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

  3. 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.

  4. Oxygen pathway modeling estimates high reactive oxygen species production above the highest permanent human habitation.

    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.

  5. Behaviour of high stretch bolts in tension working as part of elements of steel structures, and their tendency to delayed fracturing

    Moyseychik Evgeniy Alekseevich

    2014-12-01

    Full Text Available In the article, the author has proven that manufacturing and installation errors, as well as contact deformations of high strength bolts, if analyzed as part of tensile connections of steel structures, work in eccentric tension. In pursuance of the effective state standards, the analysis of these bolts is based on the axial tension. The author has analyzed the failure of a steel structure, caused by the fracture of eccentrically loaded bolts made of steel grade XC 42 (France, or C40 (Germany, that later followed the delayed fracturing pattern. The author provides the findings of the lab tests, whereby the above bolts were tested in the presence of an angle washer. The author has also analyzed the findings of low-temperature tests of bolts in tension. The author demonstrates that the strength of high strength bolts is driven by the material, the structure shape, and the thermal treatment pattern. Eccentric tension tests of bolts have proven that cracks emerge in the areas of maximal concentration of stresses (holes in shafts, etc. that coincide with the areas where fibers are in tension; cracks tend to follow the delayed fracturing pattern, and their development is accompanied by the deformation-induced metal heating in the fracture area. Therefore, the analysis of high strength bolts shall concentrate on the eccentric tension with account for contact-induced loads, while the tendency to delayed fracturing may be adjusted through the employment of both metallurgical and process techniques.

  6. 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.

  7. Development of high power chemical oxygen lodine laser

    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.

  8. Arterial oxygen tension and pulmonary ventilation in horses placed in the Anderson Sling suspension system after a period of lateral recumbency and anaesthetised with constant rate infusions of romifidine and ketamine.

    François, I; Lalèyê, F-X; Micat, M; Benredouane, K; Portier, K

    2014-09-01

    Some controversy exists over whether or not horses' recovery and cardiopulmonary function are affected by suspension in slings. To measure arterial oxygen tension and pulmonary ventilation in anaesthetised horses placed in a standing position in an Anderson Sling (AS) after a period of right lateral recumbency (RLR). Randomised crossover experimental study. Six Standardbred horses were anaesthetised twice. Catheters were inserted into the right jugular vein and the left carotid artery. After premedication with romifidine, anaesthesia was induced with diazepam and ketamine. Following 50 min in RLR, horses were maintained in either RLR or AS for an additional 60 min through to recovery. Anaesthesia was maintained i.v. with a constant rate infusion of romifidine and ketamine. Heart rate, respiratory rate, mean arterial pressure, expiratory tidal volume, minute volumes and end tidal CO2 were monitored continuously. Venous and arterial bloods were sampled for lactate concentration, creatine kinase activity and blood gas analysis before premedication, after induction, every 20 min for 100 min, as soon as the horse was standing (TR), and 24 h later. The data were averaged within 2 anaesthetic periods: P1, 0-20 min; and P2, 40-100 min. During P2, horses in the RLR group had lower arterial oxygen tension (P = 0.001), higher alveolar-arterial oxygen tension gradient (P = 0.005), higher respiratory rate (P = 0.04) and higher minute volumes (P = 0.04) than horses in the AS group. Arterial CO2 tension and mean arterial pressure increased in the AS group during P2 (P = 0.01 and 0.02 respectively). The recoveries were judged better in the AS group than in the RLR group (P = 0.01). During TR, lactate were higher in the RLR group than in the AS group (P = 0.007). Creatine kinase activities were higher in the AS group at 24 h vs. TR (P = 0.02). Anderson Sling suspension after a period of recumbency improves cardiopulmonary function and recovery quality in horses and

  9. Characterization of ZnO-degraded varistors used in high-tension devices

    Ramirez, M.A.; Simoes, A.Z.; Marquez, M.A.; Maniette, Y.; Cavalheiro, A.A; Varela, J.A.

    2007-01-01

    The effects of the degradation process on the structural, microstructural and electrical properties of ZnO-based varistors were analyzed. Rietveld refinement showed that the BiO 2-x phase is affected by the degradation process. Besides the changes in the spinel phase, the degradation process also affects the lattice microstrain in the ZnO phase. Scanning electron microscopy analysis showed electrode-melting failure, while wavelength dispersive X-ray spectroscopy qualitative analysis showed deficiency of oxygen species at the grain boundaries in the degraded samples. Atomic force microscopy using electrostatic mode force illustrated a decrease in the charge density at the grain boundaries of the degraded sample. Transmission electron microscopy showed submicrometric spinel grains embedded in a ZnO matrix, but their average grain size is smaller in the degraded sample than in the standard one. Long pulses appeared to be more harmful for the varistors' properties than short ones, causing higher leakage current values. The electrical characteristics of the degraded sample are partially restored after heat treatment in an oxygen-rich atmosphere

  10. A cohesion/tension mechanism explains the gating of water channels (aquaporins) in Chara internodes by high concentration.

    Ye, Qing; Wiera, Boguslaw; Steudle, Ernst

    2004-02-01

    Isolated internodes of Chara corallina have been used to study the gating of aquaporins (water channels) in the presence of high concentrations of osmotic solutes of different size (molecular weight). Osmolytes were acetone and three glycol ethers: ethylene glycol monomethyl ether (EGMME), diethylene glycol monomethyl ether (DEGMME), and triethylene glycol monoethyl ether (TEGMEE). The 'osmotic efficiency' of osmolytes was quite different. Their reflection coefficients ranged between 0.15 (acetone), 0.59 (EGMME), 0.78 (DEGMME), and 0.80 (TEGMEE). Bulk water permeability (Lp) and diffusive permeabilities (Ps) of heavy water (HDO), hydrogen peroxide (H2O2), acetone, and glycol ethers (EGMME, DEGMME, and TEGMEE) were measured using a cell pressure probe. Cells were treated with different concentrations of osmotic solutes of up to 800 mM ( approximately 2.0 MPa of osmotic pressure). Inhibition of aquaporin activity increased with both increasing concentration and size of solutes (reflection coefficients). As cell Lp decreased, Ps increased, indicating that water and solutes used different passages across the plasma membrane. Similar to earlier findings of an osmotic gating of ion channels, a cohesion/tension model of the gating of water channels in Chara internodes by high concentration is proposed. According to the model, tensions (negative pressures) within water channels affected the open/closed state by changing the free energy between states and favoured a distorted/collapsed rather than the open state. They should have differed depending on the concentration and size of solutes that are more or less excluded from aquaporins. The bigger the solute, the lower was the concentration required to induce a reversible closure of aquaporins, as predicted by the model.

  11. Non-site-specific allosteric effect of oxygen on human hemoglobin under high oxygen partial pressure.

    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.

  12. 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.

  13. Creating Tension in Writing.

    Folta, Bernarr

    This paper discusses the rationale and teaching methods for a six-week unit, for a high school freshman English Class, on perception, semantics, and writing, which places special focus on developing tension in student writing. The first four objectives of the course focus on perception and the next two focus on semantics. The seventh…

  14. Contemporary Bilingual Life at a Canadian High School: Choices, Risks, Tensions, and Dilemmas.

    Goldstein, Tara

    2003-01-01

    Reports on a ethnographic study that investigated how immigrant high school students used Cantonese and English to achieve academic and social success in a Canadian high school where English was the language of instruction. Argues that immigrant students found meaningful ways to acquire the cultural capital of the dominant society. (CAJ)

  15. Behaviour of Nano Silica in Tension Zone of High Performance Concrete Beams

    Jaishankar, P.; Vivek, D.

    2017-07-01

    High performance concrete (HPC) is similar to High strength concrete (HSC).It is because of lowering of water to cement ratio, which is needed to attain high strength and generally improves other properties. This concrete contains one or more cementitious materials such as fly ash, Silica fume or ground granulated blast furnace slag and usually a super plasticizer. The term ‘high performance’ is somewhat different because the essential feature of this concrete is that it’s ingredients and proportions are specifically chosen so as to have particularly appropriate properties for the expected use of the structure such as high strength and low permeability. Usage of nano scale properties such as Nano SiO2 can result in dramatically improved properties from conventional grain size materials of same chemical composition. This project is more interested in evaluate the behaviour of nano silica in concrete for 5%, 10%, and 15% volume fraction of cement. Flexural test for beams were conducted with two point loads, at different percentage as mentioned above. From results interpolated, Nano silica with higher order replacement gives optimized results compared to control specimens.

  16. Characterization of a New Fully Recycled Carbon Fiber Reinforced Composite Subjected to High Strain Rate Tension

    Meftah, H.; Tamboura, S.; Fitoussi, J.; BenDaly, H.; Tcharkhtchi, A.

    2018-06-01

    The aim of this study is the complete physicochemical characterization and strain rate effect multi-scale analysis of a new fully recycled carbon fiber reinforced composites for automotive crash application. Two composites made of 20% wt short recycled carbon fibers (CF) are obtained by injection molding. The morphology and the degree of dispersion of CF in the matrixes were examined using a new ultrasonic method and SEM. High strain tensile behavior up to 100 s-1 is investigated. In order to avoid perturbation due to inertial effect and wave propagation, the specimen geometry was optimized. The elastic properties appear to be insensitive to the strain rate. However, a high strain rate effect on the local visco-plasticity of the matrix and fiber/matrix interface visco-damageable behavior is emphasized. The predominant damage mechanisms evolve from generalized matrix local ductility at low strain rate regime to fiber/matrix interface debonding and fibers pull-out at high strain rate regime.

  17. The interfacial tension of the mercury —1 M HClO4− solution interface at high potentials; comparison with double-layer capacitance measurements

    Sluyters-Rehbach, M.; Woittiez, W.J.A.; Sluyters, J.H.

    Interfacial tension values have been measured in order to calculate the electrical charge density as a function of potential. The results are in accordance with those obtained from double-layer capacitance data reported earlier2,3, also at highly positive potentials.

  18. 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

  19. Formation of highly oxygenated organic molecules from aromatic compounds

    Molteni, Ugo; Bianchi, Federico; Klein, Felix; El Haddad, Imad; Frege, Carla; Rossi, Michel J.; Dommen, Josef; Baltensperger, Urs

    2018-02-01

    Anthropogenic volatile organic compounds (AVOCs) often dominate the urban atmosphere and consist to a large degree of aromatic hydrocarbons (ArHCs), such as benzene, toluene, xylenes, and trimethylbenzenes, e.g., from the handling and combustion of fuels. These compounds are important precursors for the formation of secondary organic aerosol. Here we show that the oxidation of aromatics with OH leads to a subsequent autoxidation chain reaction forming highly oxygenated molecules (HOMs) with an O : C ratio of up to 1.09. This is exemplified for five single-ring ArHCs (benzene, toluene, o-/m-/p-xylene, mesitylene (1,3,5-trimethylbenzene) and ethylbenzene), as well as two conjugated polycyclic ArHCs (naphthalene and biphenyl). We report the elemental composition of the HOMs and show the differences in the oxidation patterns of these ArHCs. A potential pathway for the formation of these HOMs from aromatics is presented and discussed. We hypothesize that AVOCs may contribute substantially to new particle formation events that have been detected in urban areas.

  20. Formation of highly oxygenated organic molecules from aromatic compounds

    U. Molteni

    2018-02-01

    Full Text Available Anthropogenic volatile organic compounds (AVOCs often dominate the urban atmosphere and consist to a large degree of aromatic hydrocarbons (ArHCs, such as benzene, toluene, xylenes, and trimethylbenzenes, e.g., from the handling and combustion of fuels. These compounds are important precursors for the formation of secondary organic aerosol. Here we show that the oxidation of aromatics with OH leads to a subsequent autoxidation chain reaction forming highly oxygenated molecules (HOMs with an O : C ratio of up to 1.09. This is exemplified for five single-ring ArHCs (benzene, toluene, o-/m-/p-xylene, mesitylene (1,3,5-trimethylbenzene and ethylbenzene, as well as two conjugated polycyclic ArHCs (naphthalene and biphenyl. We report the elemental composition of the HOMs and show the differences in the oxidation patterns of these ArHCs. A potential pathway for the formation of these HOMs from aromatics is presented and discussed. We hypothesize that AVOCs may contribute substantially to new particle formation events that have been detected in urban areas.

  1. Minor oxygenated cannabinoids from high potency Cannabis sativa L.

    Ahmed, Safwat A; Ross, Samir A; Slade, Desmond; Radwan, Mohamed M; Khan, Ikhlas A; ElSohly, Mahmoud A

    2015-09-01

    Nine oxygenated cannabinoids were isolated from a high potency Cannabis sativa L. variety. Structure elucidation was achieved using spectroscopic techniques, including 1D and 2D NMR, HRMS and GC-MS. These minor compounds include four hexahydrocannabinols, four tetrahydrocannabinols, and one hydroxylated cannabinol, namely 9α-hydroxyhexahydrocannabinol, 7-oxo-9α-hydroxyhexa-hydrocannabinol, 10α-hydroxyhexahydrocannabinol, 10aR-hydroxyhexahydrocannabinol, Δ(9)-THC aldehyde A, 8-oxo-Δ(9)-THC, 10aα-hydroxy-10-oxo-Δ(8)-THC, 9α-hydroxy-10-oxo-Δ(6a,10a)-THC, and 1'S-hydroxycannabinol, respectively. The latter compound showed moderate anti-MRSa (IC50 10.0 μg/mL), moderate antileishmanial (IC50 14.0 μg/mL) and mild antimalarial activity against Plasmodium falciparum (D6 clone) and P. falciparum (W2 clone) with IC50 values of 3.4 and 2.3 μg/mL, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Highly Oxygenated Flavonoids from the Leaves of Nicotiana plumbaginifolia (Solanaceae

    Md. Shafiullah Shajib

    2017-11-01

    Full Text Available 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',5'-methylenedioxyflavone (1, 3,3' ,4' ,5',5,6,7,8-octamethoxyflavone (2, exoticin, 6,7,4',5'-dimethylenedioxy-3,5,3'-trimethoxyflavone (3 and ( 3,3' ,4',5,5',8-hexamethoxy-6,7-methylenedioxyflavone (4 from the leaves of N. plumbaginifolia . All these flavonoids are rather rare natural products, and only found in a few genera, e.g.,Polygonum and Murraya. The structures of the isolated flavonoids were elucidated by comprehensive spectroscopic analyses, e.g., UV, 1H, 13C NMR, DEPT, HSQC, HMBC and MS.

  3. High Pressure Electrochemical Oxygen Generation for ISS, Phase I

    National Aeronautics and Space Administration — Giner, Inc. has developed an advanced electrochemical static vapor feed oxygen (O2) concentrator (SVFOC) that offers a simple alternative to the use of pressure...

  4. High Pressure Oxygen Generation for Future Exploration Missions, Phase II

    National Aeronautics and Space Administration — The proposed innovation is the development of a cathode feed electrolysis cell stack capable of generating 3600 psi oxygen at a relevant scale for future exploration...

  5. 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...

  6. Pinning by oxygen vacancies in high-Tc superconductors

    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

  7. 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.

  8. On developing a thesis for Reproductive Endocrinology and Infertility fellowship: a case study of ultra-low (2%) oxygen tension for extended culture of human embryos.

    Kaser, Daniel J

    2017-03-01

    Fellows in Reproductive Endocrinology and Infertility training are expected to complete 18 months of clinical, basic, or epidemiological research. The goal of this research is not only to provide the basis for the thesis section of the oral board exam but also to spark interest in reproductive medicine research and to provide the next generation of physician-scientists with a foundational experience in research design and implementation. Incoming fellows often have varying degrees of training in research methodology and, likewise, different career goals. Ideally, selection of a thesis topic and mentor should be geared toward defining an "answerable" question and building a practical skill set for future investigation. This contribution to the JARG Young Investigator's Forum revisits the steps of the scientific method through the lens of one recently graduated fellow and his project aimed to test the hypothesis that "sequential oxygen exposure (5% from days 1 to 3, then 2% from days 3 to 5) improves blastocyst yield and quality compared to continuous exposure to 5% oxygen among human preimplantation embryos."

  9. High-temperature vaporization behavior of oxygen-deficient thoria

    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

  10. 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.

  11. Acetazolamide improves cerebral oxygenation during exercise at high altitude

    Vuyk, J.; Bos, J. van den; Terhell, K.; Bos, R. de; Vletter, A.; Valk, P.; Beuzekom, M. van; Kleef, J. van; Dahan, A.

    2006-01-01

    Acute mountain sickness is thought to be triggered by cerebral hypoxemia and be prevented by acetazolamide (Actz). The effect of Actz on cerebral oxygenation at altitude remains unknown. In 16 members of the 2005 Dutch Cho Oyu (8201 m, Tibet) expedition, the influence of Actz and exercise (750 mg PO

  12. Fabrication of high surface area graphene electrodes with high performance towards enzymatic oxygen reduction

    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.

  13. 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.

  14. Width and string tension of the flux tube in SU(2) lattice gauge theory at high temperature

    Chagdaa, S.; Galsandorj, E.; Laermann, E.; Purev, B.

    2018-02-01

    We study the profiles of the flux tube between a static quark and an antiquark in quenched SU(2) lattice gauge theory at temperatures around the deconfinement phase transition. The physical width of the flux tube and the string tension have been determined from the transverse profiles and the q\\bar{q} potential, respectively. Exploiting the computational power of a GPU accelerator in our flux tube investigation, we achieve much higher statistics through which we can increase the signal to noise ratio of our observables in the simulation. This has allowed the investigation of larger lattices as well as larger separations between the quarks than in our previous work. The improved accuracy gives us better results for the width and the string tension. The physical width of the flux tube increases with the temperature up to around T c while keeping its increasing dependence on the q\\bar{q} separation. The string tension results are compared for two different sizes of the lattice. As the lattice becomes larger and finer together with the improved precision, the temperature dependent string tension tends to have a smaller value than the previous one.

  15. A highly precise frequency-based method for estimating the tension of an inclined cable with unknown boundary conditions

    Ma, Lin

    2017-11-01

    This paper develops a method for precisely determining the tension of an inclined cable with unknown boundary conditions. First, the nonlinear motion equation of an inclined cable is derived, and a numerical model of the motion of the cable is proposed using the finite difference method. The proposed numerical model includes the sag-extensibility, flexural stiffness, inclination angle and rotational stiffness at two ends of the cable. Second, the influence of the dynamic parameters of the cable on its frequencies is discussed in detail, and a method for precisely determining the tension of an inclined cable is proposed based on the derivatives of the eigenvalues of the matrices. Finally, a multiparameter identification method is developed that can simultaneously identify multiple parameters, including the rotational stiffness at two ends. This scheme is applicable to inclined cables with varying sag, varying flexural stiffness and unknown boundary conditions. Numerical examples indicate that the method provides good precision. Because the parameters of cables other than tension (e.g., the flexural stiffness and rotational stiffness at the ends) are not accurately known in practical engineering, the multiparameter identification method could further improve the accuracy of cable tension measurements.

  16. Effect of oxygen supplementation in a hatchery at high altitude and ...

    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 ...

  17. Effect of culture at low oxygen tension on the expression of heat shock proteins in a panel of melanoma cell lines.

    Christopher Shipp

    Full Text Available Tumours are commonly hypoxic and this can be associated with aggressive tumour type, metastasis and resistance to therapy. Heat shock proteins (hsps are induced in response to hypoxia, provide cancer cells with protection against tumour-associated stressors and chaperone oncoproteins that drive tumour proliferation. This study examined the effect of different oxygen concentrations on the expression of hsps in melanoma cell lines.Melanoma cell lines were cultured in 2% and 20% O(2. Expression of Hsp90, Hsp70, Hsp60, Hsp40 and Hsp32 proteins were determined by flow cytometry.Growth rates and viability were reduced in the majority of cell lines by culture in 2% O(2. Hsp expression was different in 2% compared to 20% O(2 and changes in Hsp90 expression correlated with cell line generation time (P<0.005 and viability (P<0.01. Greater total hsp expression correlated with improved viability in 2% but not 20% O(2 (P<0.05. Relative expression of the different hsps was consistent across cell lines and each correlated with the others (P = 0.0001 but not with Hsp32. Hsp expression was inversely correlated with cell line adhesion to laminin as well as collagen type IV and Breslow depth of the original primary tumour tissue (P<0.05, but not with Clark level or patient survival. All five hsps were identified on the cell surface.Culture in 2% O(2 variably altered hsp expression in a panel of melanoma cell lines. Hsp expression was associated with certain cell line characteristics and clinical parameters of the originating tumour.

  18. Effects of hyperoxia on 18F-fluoro-misonidazole brain uptake and tissue oxygen tension following middle cerebral artery occlusion in rodents: Pilot studies.

    Tim D Fryer

    Full Text Available Mapping brain hypoxia is a major goal for stroke diagnosis, pathophysiology and treatment monitoring. 18F-fluoro-misonidazole (FMISO positron emission tomography (PET is the gold standard hypoxia imaging method. Normobaric hyperoxia (NBO is a promising therapy in acute stroke. In this pilot study, we tested the straightforward hypothesis that NBO would markedly reduce FMISO uptake in ischemic brain in Wistar and spontaneously hypertensive rats (SHRs, two rat strains with distinct vulnerability to brain ischemia, mimicking clinical heterogeneity.Thirteen adult male rats were randomized to distal middle cerebral artery occlusion under either 30% O2 or 100% O2. FMISO was administered intravenously and PET data acquired dynamically for 3hrs, after which magnetic resonance imaging (MRI and tetrazolium chloride (TTC staining were carried out to map the ischemic lesion. Both FMISO tissue uptake at 2-3hrs and FMISO kinetic rate constants, determined based on previously published kinetic modelling, were obtained for the hypoxic area. In a separate group (n = 9, tissue oxygen partial pressure (PtO2 was measured in the ischemic tissue during both control and NBO conditions.As expected, the FMISO PET, MRI and TTC lesion volumes were much larger in SHRs than Wistar rats in both the control and NBO conditions. NBO did not appear to substantially reduce FMISO lesion size, nor affect the FMISO kinetic rate constants in either strain. Likewise, MRI and TTC lesion volumes were unaffected. The parallel study showed the expected increases in ischemic cortex PtO2 under NBO, although these were small in some SHRs with very low baseline PtO2.Despite small samples, the apparent lack of marked effects of NBO on FMISO uptake suggests that in permanent ischemia the cellular mechanisms underlying FMISO trapping in hypoxic cells may be disjointed from PtO2. Better understanding of FMISO trapping processes will be important for future applications of FMISO imaging.

  19. Graphene Oxide Bionanocomposite Coatings with High Oxygen Barrier Properties

    Ilke Uysal Unalan

    2016-12-01

    Full Text Available In this work, we present the development of bionanocomposite coatings on poly(ethylene terephthalate (PET with outstanding oxygen barrier properties. Pullulan and graphene oxide (GO were used as main polymer phase and nanobuilding block (NBB, respectively. The oxygen barrier performance was investigated at different filler volume fractions (ϕ and as a function of different relative humidity (RH values. Noticeably, the impermeable nature of GO was reflected under dry conditions, in which an oxygen transmission rate (OTR, mL·m−2·24 h−1 value below the detection limit of the instrument (0.01 mL·m−2·24 h−1 was recorded, even for ϕ as low as 0.0004. A dramatic increase of the OTR values occurred in humid conditions, such that the barrier performance was totally lost at 90% RH (the OTR of coated PET films was equal to the OTR of bare PET films. Modelling of the experimental OTR data by Cussler’s model suggested that the spatial ordering of GO sheets within the main pullulan phase was perturbed because of RH fluctuations. In spite of the presence of the filler, all the formulations allowed the obtainment of final materials with haze values below 3%, the only exception being the formulation with the highest loading of GO (ϕ ≈ 0.03. The mechanisms underlying the experimental observations are discussed.

  20. Ultimate stress increase in unbonded tendons in post-tensioned indeterminate I-beams cast with high strength normal and self compacting concrete

    Yousef Askari Dolatabad

    2018-06-01

    Full Text Available The use of un-bonded tendons is prevalent in post-tensioned concrete structures. Equations for prediction of stress in un-bonded tendons of post-tensioned normal (vibrating concrete flexural members have been given in various codes. They are based on experience and don’t account all of important parameters such as concrete strength (normal and high strength and its type (vibrating and non-vibrating concrete. Since self-compacting concrete (SCC is nearly a new innovation therefore, understanding the implementation of this type of non-vibrating concrete on the ultimate unbonded tendon stress is critical. For this aim, in this paper there are presented experimental results of six continuous un-bonded post-tensioned I-beams in two groups were casted and monitored by different electrical strain gauges. In the first tested group, the beams (UPN1-12, UPN1-18, UPN1-22 were consisting of high strength normal concrete (HSNC where as in the second group (UPS1-12, UPS1-18, UPS1-22 high strength self-compacting concrete (HSSCC were tested. The variables included the type of concrete and percentage of bounded non-prestressed steel. Experimental monitored results of ultimate stress increase in unbonded tendons are compared with predicted equations of different researchers and standards. It was found that, the proposed equation is in better agreement with the test results. The results of standard error of estimate Sy/x, indicates that for two types of HSCs, the ACI 318-2011 provides better estimates than AASHTO-2010 model whereas this model provides better estimates than BS 8110-97. Keywords: Post-tensioned, Unbonded tendons, Stress increase, High strength normal and self-compacting concrete, Continuous beams

  1. Estimated Trans-Lamina Cribrosa Pressure Differences in Low-Teen and High-Teen Intraocular Pressure Normal Tension Glaucoma: The Korean National Health and Nutrition Examination Survey

    Lee, Si Hyung; Kwak, Seung Woo; Kang, Eun Min; Kim, Gyu Ah; Lee, Sang Yeop; Bae, Hyoung Won; Seong, Gong Je; Kim, Chan Yun

    2016-01-01

    Background To investigate the association between estimated trans-lamina cribrosa pressure difference (TLCPD) and prevalence of normal tension glaucoma (NTG) with low-teen and high-teen intraocular pressure (IOP) using a population-based study design. Methods A total of 12,743 adults (? 40 years of age) who participated in the Korean National Health and Nutrition Examination Survey (KNHANES) from 2009 to 2012 were included. Using a previously developed formula, cerebrospinal fluid pressure (C...

  2. High-voltage-powered transistorized preamplifier; Pre-amplificateur transistorise avec alimentation haute tension; Vysokovol'tnyj ehnergeticheskij predvaritel'nyj usilitel' na tranzistorakh; Preamplificador transistorizado alimentado con alta tension

    Wilson, Jr, W E; Wakefield, A W [University of Washington, Seattle, WA (United States)

    1962-04-15

    One of the problems that is frequently met in the field of nuclear electronics is that of coupling the signal from a high-impedance pulse-type radiation detector to a low-impedance transmission line. Radiation detectors and their associated counting equipment are often separated by a considerable distance and some efficient means of transmitting the signal from the detector to the counting system must be provided. In practice, a low-impedance coaxial cable is used for the transmission line and a cathode-follower or emitter-follower circuit is used to achieve the required impedance match. This paper describes a unique emitter-follower circuit that has been utilized very successfully at the University of Washington. The emitter-follower circuit is unique in that power for the transistor circuit is derived from the high voltage that is supplied to the radiation detector. The two pnp alloy-junction transistors employed in the preamplifier yield.a voltage gain of unity over a dynamic range of from 1 mV to 5 V. Stabilization of the operating voltage for the emitter-follower circuit is provided by a small zener diode. The current drain of a typical remote-scintillation detector employing the circuit ranges from 0.35 to 0.65 mA when the high voltage is supplied to the scintillation detector is varied from 800 to 1 500 V. The unit will drive 500 ft of 52-{Omega} coaxial line with a 25% loss in pulse amplitude and has been used with remotely operated scintillation-type detectors and BF{sub 3}-type neutron detectors with excellent results. (author) [French] Un des problemes qui se posent frequemment en electronique nucleaire est celui de l'adaptation d'un detecteur d'impulsions a grande impedance a une ligne de transmission a basse impedance. La difficulte est la suivante: les detecteurs etant souvent sensiblement eloignes des appareils de comptage connexes, il faut prevoir un moyen efficace de transmettre le signal du detecteur au dispositif de comptage. En pratique, on

  3. Accuracy of tension and saturation-based oxygen indices in the assessment of disease severity and its progress in adults with acute respiratory distress syndrome

    Ghada F El-Baradey

    2016-01-01

    Conclusion: OSI can be used as a noninvasive index for the assessment of ARDS severity in adults as it correlates significantly with PF ratio and OI with high sensitivity and specificity to predict ICU mortality.

  4. The influence of high-heeled shoes on strain and tension force of the anterior talofibular ligament and plantar fascia during balanced standing and walking.

    Yu, Jia; Wong, Duo Wai-Chi; Zhang, Hongtao; Luo, Zong-Ping; Zhang, Ming

    2016-10-01

    High-heeled shoes have the capability to alter the strain and tension of ligamentous structures between the foot and ankle, which may result in ankle instability. However, high-heeled shoes can also reduce the strain on plantar fascia, which may be beneficial for the treatment of plantar fasciitis. In this study, the influence of heel height on strain and tension force applied to the anterior talofibular ligament (ATL) and plantar fascia were investigated. A three-dimensional finite element model of coupled foot-ankle-shoe complex was constructed. Four heel heights were studied in balanced standing: 0 in. (0cm), 1 in. (2.54cm), 2 in. (5.08cm), and 3 in. (7.62cm). A walking analysis was performed using 2-in. (5.08cm) high-heeled shoes. During balanced standing, the tension force on the ATL increased from 14.8N to 97.0N, with a six-fold increase in strain from 0 in. to 3 in. (0-7.62cm). The tension force and the average strain on the plantar fascia decreased from 151.0N (strain: 0.74%) to 59.6N (strain: 0.28%) when the heel height increased from 0 in. to 2 in. (0-5.08cm). When heel height reached 3 in. (7.62cm), the force and average strain increased to 278.3N (strain: 1.33%). The walking simulation showed that the fascia stretched out while the ATL loading decreased during push off. The simulation outcome demonstrated the influence of heel height on ATL alteration and plantar fascia strain, which implies risks for ankle injury and suggests guidance for the treatment of plantar fasciitis. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

  5. Engineering High-Energy Interfacial Structures for High-Performance Oxygen-Involving Electrocatalysis.

    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.

  6. Density and surface tension of high-temperature stratifying mixtures of alkali metal bromides and lithium fluoride

    Rukavishnikova, I.V.; Lokett, V.N.; Burukhin, A.S.; Stepanov, V.P.

    2006-01-01

    The density and interphase tension of molten mixtures of lithium fluoride with potassium, rubidium, and cesium bromides were measured over the temperature range 1120-1320 K in the region of limited mutual solubility by the hydrostatic weighing and meniscus weight methods. The dependences of properties on the size ratio between the mixed ions were determined. The critical order parameters for systems with the predominantly ionic character of interparticle interactions were estimated [ru

  7. High-pressure oxygenation of thin-wall YBCO single-domain samples

    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

  8. The effects of high perioperative inspiratory oxygen fraction for adult surgical patients

    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...

  9. Increased long-term mortality after a high perioperative inspiratory oxygen fraction during abdominal surgery

    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...

  10. Long term high flow heated oxygen treatment in COPD – lung function and physical ability

    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...

  11. Study on Oxygen Supply Standard for Physical Health of Construction Personnel of High-Altitude Tunnels

    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.

  12. High oxygen condition facilitates the differentiation of mouse and human pluripotent stem cells into pancreatic progenitors and insulin-producing cells.

    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.

  13. 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.

  14. Liquid oxygen liquid acquisition device bubble point tests with high pressure lox at elevated temperatures

    Jurns, J. M.; Hartwig, J. W.

    2012-04-01

    When transferring propellant in space, it is most efficient to transfer single phase liquid from a propellant tank to an engine. In earth's gravity field or under acceleration, propellant transfer is fairly simple. However, in low gravity, withdrawing single-phase fluid becomes a challenge. A variety of propellant management devices (PMDs) are used to ensure single-phase flow. One type of PMD, a liquid acquisition device (LAD) takes advantage of capillary flow and surface tension to acquire liquid. The present work reports on testing with liquid oxygen (LOX) at elevated pressures (and thus temperatures) (maximum pressure 1724 kPa and maximum temperature 122 K) as part of NASA's continuing cryogenic LAD development program. These tests evaluate LAD performance for LOX stored in higher pressure vessels that may be used in propellant systems using pressure fed engines. Test data shows a significant drop in LAD bubble point values at higher liquid temperatures, consistent with lower liquid surface tension at those temperatures. Test data also indicates that there are no first order effects of helium solubility in LOX on LAD bubble point prediction. Test results here extend the range of data for LOX fluid conditions, and provide insight into factors affecting predicting LAD bubble point pressures.

  15. Mentoring Preservice Teachers: Identifying Tensions and Possible Resolutions

    Hudson, Peter; Hudson, Sue

    2018-01-01

    Tensions can occur in the mentor-mentee relationship during school-based professional experiences that require problem solving. What are the tensions for mentor teachers in preservice teacher education and how might these tensions be resolved? This qualitative study collected data from 31 high school mentor teachers about tensions experienced with…

  16. Reactor vessel stud tensioner

    Malandra, L.J.; Beer, R.W.; Salton, R.B.; Spiegelman, S.R.; Cognevich, M.L.

    1982-01-01

    A quick-acting stud tensioner, for facilitating the loosening or tightening of a stud nut on a reactor vessel stud, has gripper jaws which when the tensioner is lowered into engagement with the upper end of the stud are moved inwards to grip the upper end and which when the tensioner is lifted move outward to release the upper end. (author)

  17. A model of the generation and transport of ozone in high-tension nozzle driven corona inside a novel diode

    Vijayan, T.; Patil, Jagadish G.

    2012-01-01

    The genesis and transport of ozone (O 3 ) are investigated in a novel plasma diode and described in this paper. The innovative cathode (K) of this axial symmetric diode which operated at the high voltage (φ 0 ), has a large number of sharpened nozzles located on different radial planes of its central tubular-mast and is encircled by the anode (A). The nozzles played the dual role of oxygen (O 2 ) injection as well as creation of high electric field (E) in the A-K gap, enabled the formation of a cold corona. Electrons in the corona under the influence of E moved towards anode, collided with O 2 and created the O radicals. O in turn joined the free O 2 and formed O 3 . The evolution of O 3 here is modeled in various O 2 pressure (P), electron density (n e ), and temperature (T) in terms of the major reaction modes involving e, O, O 2 , and O 3 . Typical steady state O 3 density attained so in P ∼ bar, n e ∼ 10 15 m −3 and T∼ 300 K is over 10 25 m −3 and that of O lower ∼10 20 m −3 . Both the O and O 3 densities increased with an enhanced n e of avalanche multiplications in corona. O 3 increased also with a higher P but the temporal O reversed in trend midway and reduced with P towards the steady state. A sharp decline in diode resistance with smaller A-K gap induced finite discharge current and led to the undesired heating of corona. It is shown that the O 3 density reduced with the temperature rise but O density reduced with the T rise up to 500 K and then rose modestly with the further T increase.

  18. A model of the generation and transport of ozone in high-tension nozzle driven corona inside a novel diode

    Vijayan, T.; Patil, Jagadish G.

    2012-12-01

    The genesis and transport of ozone (O3) are investigated in a novel plasma diode and described in this paper. The innovative cathode (K) of this axial symmetric diode which operated at the high voltage (ϕ0), has a large number of sharpened nozzles located on different radial planes of its central tubular-mast and is encircled by the anode (A). The nozzles played the dual role of oxygen (O2) injection as well as creation of high electric field (E) in the A-K gap, enabled the formation of a cold corona. Electrons in the corona under the influence of E moved towards anode, collided with O2 and created the O radicals. O in turn joined the free O2 and formed O3. The evolution of O3 here is modeled in various O2 pressure (P), electron density (ne), and temperature (T) in terms of the major reaction modes involving e, O, O2, and O3. Typical steady state O3 density attained so in P ˜ bar, ne ˜ 1015 m-3 and T ˜ 300 K is over 1025 m-3 and that of O lower ˜1020 m-3. Both the O and O3 densities increased with an enhanced ne of avalanche multiplications in corona. O3 increased also with a higher P but the temporal O reversed in trend midway and reduced with P towards the steady state. A sharp decline in diode resistance with smaller A-K gap induced finite discharge current and led to the undesired heating of corona. It is shown that the O3 density reduced with the temperature rise but O density reduced with the T rise up to 500 K and then rose modestly with the further T increase.

  19. Radiosensitizers and the oxygen effects in mammalian cells

    Millar, B.C.; Fielden, E.M.; Steele, J.J.

    1979-01-01

    The survival curves for Chinese Hamster cells irradiated under various oxygen tensions have been determined. The variation in OER with oxygen concentration shows two distinct components. Between 1.4 and 7.0 μM the OER is constant with a value of 1.9. Experiments with nitroaromatic radiosensitizers in combination with low concentrations of oxygen show that they can all mimic the 'low concentration' oxygen effect. Of the compounds tested only misonidazole can apparently mimic the 'high concentration' oxygen effect although the full OER cannot be obtained with the authors cell line because of toxicity by the sensitizer. (Auth.)

  20. Clinical research on high oxygen permeable contact lens used after photorefractive keratectomy surgery

    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.

  1. Diagnosis system for nozzles in high voltage equipment; Sistema de diagnostico para boquillas en equipos de alta tension

    Ramirez Nino, Jose; Escorsa Morales, Oscar [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico); Lopez Azamar, Ernesto [Comision Federal de Electricidad (Mexico)

    2000-07-01

    The nozzles used in high voltage electrical equipment, such as power transformers and circuit breakers, constitute the elements that present greater fault risk. On the other hand, the faults in the nozzles cause, in most of the cases catastrophic damages, that expose to risk the maintenance personnel of the plant and the peripheral equipment. With the purpose of contributing with on-line monitoring techniques that indicate the nozzles condition and allow to anticipate their possible fault, the Instituto de Investigaciones Electricas (IIE) performed for the laboratory of tests of equipment and materials (LAPEM) of Comision Federal de Electricidad (CFE), a project for the development of a system for the measurement of capacitive currents in these equipments. This system allows to determine the variation in capacitance and dielectric losses, and to determine the presence of internal partial discharges in nozzles of 115, 230 and 400 kV. With this information it is possible to determine the condition of the internal isolation of the nozzles and retire them from service before deterioration takes place that puts in danger the integrity of the equipment. The management of electrical equipment of the Instituto de Investigaciones Electricas developed for LAPEM a system that measures capacitive currents of power transformer nozzles. This system was designed with the purpose of installing it in a transformer of a 400 kV machine, in the fossil power station of Tula, Hidalgo, of the Comision Federal de Electricidad. [Spanish] Las boquillas empleadas en los equipos electricos de alta tension, como transformadores de potencia e interruptores, constituyen los elementos que presentan mayor riesgo de falla. Por otro lado, las fallas en las boquillas provocan en la mayoria de los casos danos catastroficos que ponen en riesgo al personal de mantenimiento de la planta y al equipo periferico. Con la finalidad de aportar tecnicas de monitoreo en linea que indiquen el estado de las

  2. Experiment to measure oxygen opacity at high density and temperature

    Keiter, Paul; Butler, Hannah; Trantham, Matt; Mussack, Katie; Colgan, James; Fontes, Chris; Guzik, Joyce; Kilcrease, David; Perry, Ted; Orban, Chris; Ducret, Jean-Eric; La Pennec, Maelle; Turck-Chieze, Sylvaine; Mancini, Roberto; Heeter, Robert

    2017-10-01

    In recent years, there has been a debate over the abundances of heavy elements (Z >2) in the solar interior. Recent solar atmosphere models [Asplund 2009] find a significantly lower abundance for C, N, and O compared to models used roughly a decade ago. Recent opacity measurements of iron disagree with opacity model predictions [Bailey et al., 2015]. Repeated scrutiny of the experiment and data has not produced a conclusive reason for the discrepancy. New models have been implemented in the ATOMIC opacity code for low-Z elements [Colgan, 2013, Armstrong 2014], however no data currently exists to test the low-Z material models in the regime relevant to the solar convection zone. We present an experimental design using the opacity platform developed at the National Ignition Facility to study the oxygen opacity at densities and temperatures near the solar convection zone conditions. This work is funded by the U.S. DOE, through the NNSA-DS and SC-OFES Joint Program in HEDLP, Grant Number DE-NA0002956, and the NLUF Program, Grant Number DE-NA0002719, and through the LLE, University of Rochester by the NNSA/OICF under No. DE-NA0001944.

  3. Electrochemical Separation, Pumping, and Storage of Hydrogen or Oxygen into Nanocapillaries Via High Pressure MEA Seals

    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

  4. Unraveling the structure and chemical mechanisms of highly oxygenated intermediates in oxidation of organic compounds

    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.

  5. Unraveling the structure and chemical mechanisms of highly oxygenated intermediates in oxidation of organic compounds

    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.

  6. Tension-controlled single-crystallization of copper foils for roll-to-roll synthesis of high-quality graphene films

    Jo, Insu; Park, Subeom; Kim, Dongjin; San Moon, Jin; Park, Won Bae; Kim, Tae Hyeong; Hyoun Kang, Jin; Lee, Wonbae; Kim, Youngsoo; Lee, Dong Nyung; Cho, Sung-Pyo; Choi, Hyunchul; Kang, Inbyeong; Park, Jong Hyun; Lee, Jeong Soo; Hong, Byung Hee

    2018-04-01

    It has been known that the crystalline orientation of Cu substrates plays a crucial role in chemical vapor deposition (CVD) synthesis of high-quality graphene. In particular, Cu (1 1 1) surface showing the minimum lattice mismatch with graphene is expected to provide an ideal catalytic reactivity that can minimize the formation of defects, which also induces larger single-crystalline domain sizes of graphene. Usually, the Cu (1 1 1) substrates can be epitaxially grown on single-crystalline inorganic substrates or can be recrystallized by annealing for more than 12 h, which limits the cost and time-effective synthesis of graphene. Here, we demonstrate a new method to optimize the crystalline orientations of vertically suspended Cu foils by tension control during graphene growth, resulting in large-area recrystallization into Cu (1 1 1) surface as the applied tension activates the grain boundary energy of Cu and promotes its abnormal grain growth to single crystals. In addition, we found a clue that the formation of graphene cooperatively assists the recrystallization into Cu (1 1 1) by minimizing the surface energy of Cu. The domain sizes and charge carrier mobility of graphene grown on the single-crystalline Cu (1 1 1) are 5 times and ~50% increased, respectively, in comparison with those of graphene from Cu (1 0 0), indicating that the less lattice mismatch and the lower interaction energy between Cu (1 1 1) and graphene allows the growth of larger single-crystalline graphene with higher charge carrier mobility. Thus, we believe that our finding provides a crucial idea to design a roll-to-roll (R2R) graphene synthesis system where the tension control is inevitably involved, which would be of great importance for the continuous production of high-quality graphene in the future.

  7. 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)

  8. 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.

  9. Steel reinforced composite silicone membranes and its integration to microfluidic oxygenators for high performance gas exchange.

    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

  10. The study and design of tension controller

    Jun, G.; Lamei, X.

    2018-02-01

    Tension control is a wide used technology in areas such as textiles, paper and plastic films. In this article, the tension control system release and winding process is analyzed and the mathematical model of tension control system is established, and a high performance tension controller is designed. In hardware design, STM32F130 single chip microcomputer is used as the control core, which has the characteristics of fast running speed and rich peripheral features. In software design, μC/OS-II operating system is introduced to improve the efficiency of single chip microcomputer, and enhance the independence of each module, and make development and maintenance more convenient. The taper tension control is adopted in the winding part, which can effectively solve the problem of rolling shrinkage. The results show that the tension controller has the characteristics of simple structure, easy operation and stable performance.

  11. Highly Selective TiN-Supported Highly Dispersed Pt Catalyst: Ultra Active toward Hydrogen Oxidation and Inactive toward Oxygen Reduction.

    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.

  12. The stress corrosion cracking of type 316 stainless steel in oxygenated and chlorinated high temperature water

    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)

  13. A highly accurate method for determination of dissolved oxygen: Gravimetric Winkler method

    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.

  14. Kinetics of the high temperature oxygen exchange reaction on 238PuO2 powder

    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.

  15. Voltage pre-regulator without insulation with high efficiency; Pre-regulador de tension sin aislamiento con alta eficiencia

    Lopez Ramos, Octaviano

    2003-04-15

    strokes it is illustrated that the results obtained in the proposed topology are satisfactory because it succeeds in maintaining a high efficiency and a high power factor. [Spanish] Actualmente existe una problematica por el uso inadecuado e ineficiente de la energia electrica en los sistemas de alimentacion, esta problematica se va complicando aun mas con el paso del tiempo, debido a la proliferacion de equipos electronicos que no incorporan alguna solucion para dicha problematica. Esto ha ocasionado una tendencia hacia el desarrollo de sistemas que procesen con mayor eficiencia ({eta}) la energia electrica. Ademas para hacer un buen uso de la energia, se les disena para que puedan corregir el factor de potencia (FP) y por lo tanto reducen la contaminacion de armonicos en la red; los cuales provocan fallas o destruccion en otros equipos electronicos. Adicionalmente se les puede disenar para obtener una buena respuesta dinamica, lo cual asegura que podran contrarrestar eficientemente cambios de carga. La caracteristica no lineal que esta presente en todas las fuentes de alimentacion, que basan su entrada en una etapa de rectificacion y filtrado, provocan un bajo factor de potencia (FP) y una alta distorsion armonica total (THD). El factor es contaminar la red electrica, lo cual puede provocar fallas o descomposturas de otros equipos. Desde hace aproximadamente 15 anos la preocupacion por resolver este problema de uso inadecuado de la energia ha tomado importancia, desarrollando convertidores que corrigen el FP (pre-regulador) y que tradicionalmente se conectan en cascada con la tipica etapa de conversion de corriente directa a corriente directa (CD-CD) usada para regular la tension; esta solucion tiene una baja eficiencia ({eta}) y alto costo, por el exceso de componentes conectados en cascada. Sin embargo la respuesta dinamica (RD) es adecuada ya que se cuenta con etapas separadas para la correccion del FP y la regulacion. A partir de una revision del estado del arte, en

  16. Effect of a High-intensity Interval Training method on maximum oxygen consumption in Chilean schoolchildren

    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.

  17. Effect of phosphate supplementation on oxygen delivery at high altitude

    Jain, S. C.; Singh, M. V.; Rawal, S. B.; Sharma, V. M.; Divekar, H. M.; Tyagi, A. K.; Panwar, M. R.; Swamy, Y. V.

    1987-09-01

    In the present communication, effect of low doses of phosphate supplementation on short-term high altitude adaptation has been examined. Studies were carried out in 36 healthy, male, sea-level residents divided in a double blind fashion into drug and placebo treated groups. 3.2 mmol of phosphate were given orally to each subject of the drug treated group once a day for 4 days on arrival at an altitude of 3,500 m. Sequential studies were done in the subjects in both groups on the 3rd, 7th, 14th and 21st day of their altitude stay. Haemoglobin, haematocrit, erythrocyte and reticulocyte counts increased to the similar extent in both groups. Blood pH, pO2 and adenosine tri-phosphate (ATP) did not differ between the two groups. On 3rd day of the altitude stay, inorganic phosphate and 2,3-diphosphoglycerate (2,3 DPG) levels in the drug treated group increased significantly as compared to the placebo group. No significant difference in inorganic phosphate and 2,3 DPG was observed later on in the two groups. Psychological and clinical tests also indicated that the drug treated subjects felt better as compared to the placebo treated subjects. The present study suggests that low doses of phosphate increases circulating 2,3-DPG concentration which in turn brings about beneficial effect towards short term high altitude adaptation.

  18. Highly sensitive time resolved singlet oxygen luminescence detection using LEDs as the excitation source

    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)

  19. High-spatial-resolution mapping of the oxygen concentration in cortical tissue (Conference Presentation)

    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.

  20. 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

  1. Nasal high flow therapy: a novel treatment rather than a more expensive oxygen device

    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.

  2. Combustion of methane-oxygen and methane-oxygen-CFC mixtures initiated by a high-current slipping surface discharge

    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

  3. Hyperbaric oxygen therapy ameliorates acute brain injury after porcine intracerebral hemorrhage at high altitude.

    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.

  4. Electrohydrodynamics: a high-voltage direct energy conversion process; L'electrohydrodynamique: Un procede de conversion directe d'energie a haute tension

    Brun, S [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-04-15

    This analysis consists of a theoretical and practical study of a high-tension electrical power generator based on the Van de Graaff generator principle, the main difference being that the charges produced are transported by a gas in motion and not by a belt. The electrical and thermal properties of such a generator are studied, as well as the difficult problem of the production of the ionised particles used in the conversion. A certain number of results already published on this process for converting kinetic energy into electrical energy is given, as well as some possible applications in the field of space technology. (author) [French] Cette analyse est une etude theorique et pratique d'un generateur de puissance electrique a haute tension, base sur le principe du generateur Van de Graaff, la difference principale etant que les charges produites sont transportees pur un gaz en mouvement et non par une courroie. Les proprietes electriques et thermiques d'un tel generateur sont etudiees ainsi que le probleme delicat de la production des particules ionisees utilisees dans la conversion. Un certain nombre de resultats publies sur ce procede de conversion d'energie cinetique en energie electrique sont reproduits, ainsi que les applications possibles aux problemes spatiaux. (auteur)

  5. 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.

  6. Tension type headache

    Debashish Chowdhury

    2012-01-01

    Full Text Available Tension type headaches are common in clinical practice. Earlier known by various names, the diagnosis has had psychological connotations. Recent evidence has helped clarify the neurobiological basis and the disorder is increasingly considered more in the preview of neurologists. The classification, clinical features, differential diagnosis and treatment of tension type headache are discussed in this paper.

  7. Tensions in Distributed Leadership

    Ho, Jeanne; Ng, David

    2017-01-01

    Purpose: This article proposes the utility of using activity theory as an analytical lens to examine the theoretical construct of distributed leadership, specifically to illuminate tensions encountered by leaders and how they resolved these tensions. Research Method: The study adopted the naturalistic inquiry approach of a case study of an…

  8. The effect of molybdenum addition on SCC susceptibility of stainless steels in oxygenated high temperature water

    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.)

  9. Electron attachment to oxygen, ozone and other compounds of atmospheric relevance as studied with ultra-high energy resolution

    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

  10. A Universal Method to Engineer Metal Oxide-Metal-Carbon Interface for Highly Efficient Oxygen Reduction.

    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.

  11. Clinical studies with high flow nasal cannula oxygen delivery in 2015

    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

  12. Determination of oxygen content in high Tc superconductors by deuteron particle activation analysis

    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

  13. Comparison of the effectiveness of high flow nasal oxygen cannula vs. standard non-rebreather oxygen face mask in post-extubation intensive care unit patients.

    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.

  14. Optimizing oxygenation and intubation conditions during awake fibre-optic intubation using a high-flow nasal oxygen-delivery system.

    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.

  15. Optic nerve oxygenation

    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...

  16. Escape of high-energy oxygen ions through magnetopause reconnection under northward IMF

    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.

  17. Effect of high hydrostatic pressure on small oxygen-related clusters in silicon: LVM studies

    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

  18. Measurement and modelling of high pressure density and interfacial tension of (gas + n-alkane) binary mixtures

    Pereira, Luís M.C.; Chapoy, Antonin; Burgass, Rod; Tohidi, Bahman

    2016-01-01

    Highlights: • (Density + IFT) measurements are performed in synthetic reservoir fluids. • Measured systems include CO_2, CH_4 and N_2 with n-decane. • Novel data are reported for temperatures up to 443 K and pressures up to 69 MPa. • Predictive models are tested in 16 (gas + n-alkane) systems. • Best modelling results are achieved with the Density Gradient Theory. - Abstract: The deployment of more efficient and economical extraction methods and processing facilities of oil and gas requires the accurate knowledge of the interfacial tension (IFT) of fluid phases in contact. In this work, the capillary constant a of binary mixtures containing n-decane and common gases such as carbon dioxide, methane and nitrogen was measured. Experimental measurements were carried at four temperatures (313, 343, 393 and 442 K) and pressures up to 69 MPa, or near the complete vaporisation of the organic phase into the gas-rich phase. To determine accurate IFT values, the capillary constants were combined with saturated phase density data measured with an Anton Paar densitometer and correlated with a model based on the Peng–Robinson 1978 equation of state (PR78 EoS). Correlated density showed an overall percentage absolute deviation (%AAD) to measured data of (0.2 to 0.5)% for the liquid phase and (1.5 to 2.5)% for the vapour phase of the studied systems and P–T conditions. The predictive capability of models to accurately describe both the temperature and pressure dependence of the saturated phase density and IFT of 16 (gas + n-alkane) binary mixtures was assessed in this work by comparison with data gathered from the literature and measured in this work. The IFT models considered include the Parachor, the Linear Gradient Theory (LGT) and the Density Gradient Theory (DGT) approaches combined with the Volume-Translated Predictive Peng–Robinson 1978 EoS (VT-PPR78 EoS). With no adjustable parameters, the VT-PPR78 EoS allowed a good description of both solubility and

  19. Supplemental Perioperative Oxygen to Reduce Surgical Site Infection after High Energy Fracture Surgery

    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

  20. Analysis of gas turbine engines using water and oxygen injection to achieve high Mach numbers and high thrust

    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.

  1. 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...

  2. High intensity aerobic interval training improves peak oxygen consumption in patients with metabolic syndrome: CAT

    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.

  3. Study of high energy ion implantation of boron and oxygen in silicon

    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

  4. Innovative encapsulated oxygen-releasing beads for bioremediation of BTEX at high concentration in groundwater.

    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.

  5. Electron loss from multiply protonated lysozyme ions in high energy collisions with molecular oxygen

    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....

  6. Closed Loop Control of Oxygen Delivery and Oxygen Generation

    2017-08-01

    were used for this study and were connected via a USB cable to allow communication. The ventilator was modified to allow closed loop control of oxygen...connected via a USB cable to allow communication. The ventilator was modified to allow closed loop control of oxygen based on the oxygen saturation...2017-4119, 28 Aug 2017. oximetry (SpO2) and intermittent arterial blood sampling for arterial oxygen tension (partial pressure of oxygen [PaO2]) and

  7. "I Feel Trapped": The Tension Between Personal and Structural Factors of Social Isolation and the Desire for Social Integration Among Older Residents of a High-Crime Neighborhood.

    Portacolone, Elena; Perissinotto, Carla; Yeh, Jarmin Christine; Greysen, S Ryan

    2018-01-18

    The aim of this study was to examine the factors contributing to the social isolation of older residents of a high-crime neighborhood through the in-depth examination of their lived experiences. A deeper understanding of factors contributing to social isolation can allow policymakers and health care providers to create policies and programs to alleviate the social isolation of these vulnerable and understudied individuals. Participants were recruited through the support of the Housing Authority and Police and Fire Departments of Richmond, California, a town with a high-crime rate. Fifty-nine ethnographic interviews were conducted with 20 individuals of 58-95 years of age. Transcripts and fieldnotes were analyzed with a focus on the specific factors contributing the social isolation of participants. An overarching theme of tension between personal and structural factors of social isolation and desire for social integration emerged from qualitative content analysis. A tension emerged between a longing to participate in society and the immersion in a reality so dense with obstacles that made participation in society difficult to attain. Four specific themes also emerged. Three themes demonstrated underlying factors of social isolation stemming from the personal sphere and the physical and social environment. The fourth theme illustrated participants' desire for social integration. Findings demonstrate the salience of interventions and programs to make neighborhoods safe and accessible to older residents. Findings also suggest a need to reframe the conceptual framework for social isolation to better measure and alleviate this public health problem. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Initial tension loss in cerclage cables.

    Ménard, Jérémie; Émard, Maxime; Canet, Fanny; Brailovski, Vladimir; Petit, Yvan; Laflamme, George Y

    2013-10-01

    Cerclage cables, frequently used in the management of fractures and osteotomies, are associated with a high failure rate and significant loosening during surgery. This study compared the capacity to maintain tension of different types of orthopaedic cable systems. Multifilament Cobalt-Chrome (CoCr) cables with four different crimp/clamp devices (DePuy, Stryker, Zimmer and Smith&Nephew) and one non-metallic Nylon (Ny) cable from Kinamed were instrumented with a load cell to measure tension during insertion. Significant tension loss was observed with crimping for all cables (Ptensioner led to an additional unexpected tension loss (CoCr-DePuy: 18%, CoCr-Stryker: 29%, CoCr-Smith&Nephew: 33%, Ny: 46%, and CoCr-Zimmer: 52%). The simple CoCr (DePuy) cable system outperformed the more sophisticated locking devices due to its significantly better ability to prevent tension loss. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. High temperature thermoelectric properties of strontium titanate thin films with oxygen vacancy and niobium doping

    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.

  10. High temperature thermoelectric properties of strontium titanate thin films with oxygen vacancy and niobium doping

    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.

  11. 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.

  12. Tension and robustness in multitasking cellular networks.

    Jeffrey V Wong

    Full Text Available Cellular networks multitask by exhibiting distinct, context-dependent dynamics. However, network states (parameters that generate a particular dynamic are often sub-optimal for others, defining a source of "tension" between them. Though multitasking is pervasive, it is not clear where tension arises, what consequences it has, and how it is resolved. We developed a generic computational framework to examine the source and consequences of tension between pairs of dynamics exhibited by the well-studied RB-E2F switch regulating cell cycle entry. We found that tension arose from task-dependent shifts in parameters associated with network modules. Although parameter sets common to distinct dynamics did exist, tension reduced both their accessibility and resilience to perturbation, indicating a trade-off between "one-size-fits-all" solutions and robustness. With high tension, robustness can be preserved by dynamic shifting of modules, enabling the network to toggle between tasks, and by increasing network complexity, in this case by gene duplication. We propose that tension is a general constraint on the architecture and operation of multitasking biological networks. To this end, our work provides a framework to quantify the extent of tension between any network dynamics and how it affects network robustness. Such analysis would suggest new ways to interfere with network elements to elucidate the design principles of cellular networks.

  13. Effects of anesthetic agents on brain blood oxygenation level revealed with ultra-high field MRI.

    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.

  14. High Performance Electrocatalytic Reaction of Hydrogen and Oxygen on Ruthenium Nanoclusters

    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.

  15. Effects of anesthetic agents on brain blood oxygenation level revealed with ultra-high field MRI

    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)

  16. 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.

  17. Parachute Cord Tension Sensor

    National Aeronautics and Space Administration — To design and fabricate a light weight (few oz), very small (~2 inch length) parachute cord tension sensor demonstrator device.A major challenge for the CPAS (The...

  18. Leadership. Using Creative Tension.

    Cook, David L.

    1986-01-01

    Leadership involves maintaining a balance of the variables which comprise leadership. Love and fear, types of power, success and effectiveness, and driving and restraining forces are discussed as sources of the creative tension a leader uses to influence others. (MT)

  19. Spontaneous tension haemopneumothorax

    Patterson, Benjamin Oliver; Itam, Sarah; Probst, Fey

    2008-01-01

    Abstract We present a patient with sudden onset progressive shortness of breath and no history of trauma, who rapidly became haemodynamically compromised with a pneumothorax and pleural effusion seen on chest radiograph. He was treated for spontaneous tension pneumothorax but this was soon revealed to be a tension haemopneumothorax. He underwent urgent thoracotomy after persistent bleeding to explore an apical vascular abnormality seen on CT scanning. To our knowledge this is the first such c...

  20. Surface Tension Guided Hanging-Drop: Producing Controllable 3D Spheroid of High-Passaged Human Dermal Papilla Cells and Forming Inductive Microtissues for Hair-Follicle Regeneration.

    Lin, Bojie; Miao, Yong; Wang, Jin; Fan, Zhexiang; Du, Lijuan; Su, Yongsheng; Liu, Bingcheng; Hu, Zhiqi; Xing, Malcolm

    2016-03-09

    Human dermal papilla (DP) cells have been studied extensively when grown in the conventional monolayer. However, because of great deviation from the real in vivo three-dimensional (3D) environment, these two-dimensional (2D) grown cells tend to lose the hair-inducible capability during passaging. Hence, these 2D caused concerns have motivated the development of novel 3D culture techniques to produce cellular microtissues with suitable mimics. The hanging-drop approach is based on surface tension-based technique and the interaction between surface tension and gravity field that makes a convergence of liquid drops. This study used this technique in a converged drop to form cellular spheroids of dermal papilla cells. It leads to a controllable 3Dspheroid model for scalable fabrication of inductive DP microtissues. The optimal conditions for culturing high-passaged (P8) DP spheroids were determined first. Then, the morphological, histological and functional studies were performed. In addition, expressions of hair-inductive markers including alkaline phosphatase, α-smooth muscle actin and neural cell adhesion molecule were also analyzed by quantitative RT-PCR, immunostaining and immunoblotting. Finally, P8-DP microtissues were coimplanted with newborn mouse epidermal cells (EPCs) into nude mice. Our results indicated that the formation of 3D microtissues not only endowed P8-DP microtissues many similarities to primary DP, but also confer these microtissues an enhanced ability to induce hair-follicle (HF) neogenesis in vivo. This model provides a potential to elucidate the native biology of human DP, and also shows the promising for the controllable and scalable production of inductive DP cells applied in future follicle regeneration.

  1. Effect of epidural tramadol and lignocaine on physiological and behavioural changes in goats subjected to castration with a high tension band.

    Ajadi, R A; Owanikin, A O; Martins, M M; Gazal, O S

    2012-11-01

    To compare the effect of a single epidural injection of either lignocaine or tramadol on behavioural changes, anaesthetic indices, leucocyte parameters, erythrocyte sedimentation rates and concentration of cortisol in plasma in goats subjected to castration by high tension band. Ten male goats weighing 14.4 (SD 0.7) kg were randomly allocated to anaesthesia with epidural injections of tramadol (3 mg/kg), or lignocaine (4 mg/kg). Following anaesthesia, a rubber ring was applied and tensioned to the scrotal neck of each goat. Behavioural changes were noted as they occurred, and the onset of drug action (time between epidural injection and loss of pedal reflex) and duration of antinociception (time interval between disappearance and reappearance of pedal withdrawal reflex) were determined. Hearts rates, respiratory rates and rectal temperatures were determined every 15 minutes for a 90-minute period, while blood was obtained for determination of white cell counts, erythrocyte sedimentation rates and concentrations of cortisol. Anaesthetic indices were compared using Student's t-test, while physiological parameters were compared using an ANOVA for repeated measurements. Goats treated with epidural tramadol were not recumbent and continued rumination while goats treated with epidural lignocaine were recumbent and did not continue rumination. The onset of analgesia was longer (p=0.01) in goats treated with epidural tramadol (5.0 minutes; SD 1.2) than goats treated with epidural lignocaine (3.0 minutes; SD 1.1), while duration of analgesia was shorter (p=0.003) in goats treated with epidural tramadol (47.2 minutes; SD 13.1) than goats treated with epidural lignocaine (89.8 minutes; SD 23.1). There was no significant difference in heart rates, respiratory rates and erythrocyte sedimentation rates, while the concentration of cortisol in plasma differed (pcattle and where the ability of the animal to maintain standing is desired.

  2. A DLTS study of the evolution of oxygen precipitates in Si at high temperature and high pressure

    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

  3. 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...

  4. Pseudomonas aeruginosa Infectious Keratitis in a High Oxygen Transmissible Rigid Contact Lens Rabbit Model

    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

  5. Robust Tensioned Kevlar Suspension Design

    Young, Joseph B.; Naylor, Bret J.; Holmes, Warren A.

    2012-01-01

    One common but challenging problem in cryogenic engineering is to produce a mount that has excellent thermal isolation but is also rigid. Such mounts can be achieved by suspending the load from a network of fibers or strings held in tension. Kevlar fibers are often used for this purpose owing to their high strength and low thermal conductivity. A suite of compact design elements has been developed to improve the reliability of suspension systems made of Kevlar.

  6. MUSCLE TENSION DYSPHONIA

    Irena Hočevar Boltežar

    2004-07-01

    Full Text Available Background. Muscle tension dysphonia (MTD is the cause of hoarseness in almost one half of the patients with voice disorders. The otorhinolaryngologic examination discovers no evident organic lesions in the larynx at least in the beginning of the voice problems. The reason for the hoarse voice is a disordered and maladjusted activity of the muscles taking part in phonation and/or articulation. In some patients, the irregular function of the larynx results in mucosal lesions on vocal folds. The factors participating in the development of MTD, directly or indirectly influence the quality of laryngeal mucosa, the activity of the phonatory muscles and/or increase of the vocal load. In the diagnostics and treatment of the MTD a phoniatrician, a speech and language therapist and a psychologist closely cooperate with the patient who must take an active role. The treatment is a long-lasting one but resulted in a high percentage of clinical success.Conclusions. Most likely, MTD is not a special disease but only a reflection of any disorder in the complicated system of regulation and realization of phonation. The prognosis of treatment is good when all unfavourable factors participating in development of MTD are eliminated and a proper professional voice- and psychotherapy started.

  7. Accountability Strain, College Readiness Drain: Sociopolitical Tensions Involved in Maintaining a College-Going Culture in a High "Minority", High Poverty, Texas High School

    Welton, Anjale; Williams, Montrischa

    2015-01-01

    Currently school reform discourse encourages states to adopt college readiness standards. Meanwhile, federal and state accountability and related mandated reforms remain a policy concern. As such, it is important to examine the interplay between accountability and the establishment of a college-going culture in high "minority", high…

  8. The Neuroprotection Effect of Oxygen Therapy: A Systematic Review ...

    2018-04-04

    Apr 4, 2018 ... investigating the neuroprotective effect of oxygen, but the outcomes as well as ...... Neuroprotective gases – Fantasy or reality for clinical use? Prog .... of oxygen on brain tissue oxygen tension in children with severe traumatic ...

  9. Pressure balanced type membrane covered polarographic oxygen detectors for use in high temperature-high pressure water, (1)

    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)

  10. Comparison of the effect of neutron irradiation on high purity vanadium and vanadium oxygen alloys

    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

  11. Understanding the biological activity of high rate algae ponds through the calculation of oxygen balances.

    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.

  12. Anterior tension band plating for anterior tibial stress fractures in high-performance female athletes: a report of 4 cases

    Borens, Olivier; Sen, Milan K.; Huang, Russel C.; Richmond, Jeffrey; Kloen, Peter; Jupiter, Jesse B.; Helfet, David L.

    2006-01-01

    Stress fracture of the anterior tibial cortex is an extremely challenging fracture to treat, especially in the high-performance female athlete who requires rapid return to competition. Previous reports have not addressed treating these fractures in the world-class athlete with anterior plating. We

  13. The Tension between Authoritative and Dialogic Discourse: A Fundamental Characteristic of Meaning Making Interactions in High School Science Lessons

    Scott, Philip H.; Mortimer, Eduardo F.; Aguiar, Orlando G.

    2006-01-01

    In this paper, we draw upon a framework for analyzing the discursive interactions of science classrooms (Mortimer & Scott, 2003, "Meaning Making in Secondary Science Classrooms," Maidenhead, UK: Open University Press), to probe the movement between authoritative and dialogic discourse in a Brazilian high school science class. More…

  14. Numerical analysis of the effects of a high gradient magnetic field on flowing erythrocytes in a membrane oxygenator

    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

  15. Numerical analysis of the effects of a high gradient magnetic field on flowing erythrocytes in a membrane oxygenator

    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.

  16. Gastrothorax or tension pneumothorax: A diagnostic dilemma

    Singh Sarvesh

    2011-01-01

    Full Text Available Gastrothorax, a rare complication following thoracoabdominal aortic aneurysm repair, is reported. The clinical features of a gastrothorax and tension pneumothorax are similar and thus, a gastrothorax can masquerade as a tension pneumothorax. The diagnosis is made by a high level of clinical suspicion, chest X-ray shows a distended stomach with air fluid levels and a computerised tomography is useful in assessing the diaphragm and establishing the positions of the various intra-abdominal organs. Also, the risk of an intercostal drainage tube placement and the role of nasogastric tube in avoiding the development of a tension gastrothorax is highlighted.

  17. High-Flow Nasal Oxygen in Patient With Obstructive Sleep Apnea Undergoing Awake Craniotomy: A Case Report.

    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.

  18. High-resolution spectra of stars in globular clusters. VI - Oxygen-deficient red giant stars in M13

    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

  19. Five willow varieties cultivated across diverse field environments reveal stem density variation associated with high tension wood abundance

    Nicolas eBerthod

    2015-10-01

    Full Text Available Sustainable and inexpensive production of biomass is necessary to make biofuel production feasible, but represents a challenge. Five short rotation coppice (SRC willow cultivars, selected for high biomass yield, were cultivated on sites at four diverse regions of Quebec to determine their bioenergy potential in contrasting environments. Wood composition and anatomical traits were characterized. Tree height and stem diameter were measured to evaluate growth performance of the cultivars according to the diverse pedoclimatic conditions. Each cultivar showed very specific responses to its environment. While no significant variation in lignin content was observed between sites, there was variation between cultivars. Surprisingly, the pattern of substantial genotype variability in stem density was maintained across all sites. However, wood anatomy did differ between sites in a cultivar (producing high and low density wood, suggesting a probable response to an abiotic stress. Furthermore, twice as many cellulose-rich G-fibers, comprising over 50 % of secondary xylem, were also found in the high density wood, a finding with potential to bring higher value to the lignocellulosic bioethanol industry

  20. Oxidation of Inconel 625 superalloy upon treatment with oxygen or hydrogen plasma at high temperature

    Vesel, A.; Drenik, A.; Elersic, K.; Mozetič, M.; Kovač, J.; Gyergyek, T.; Stöckel, Jan; Varju, Jozef; Pánek, Radomír; Balat-Pichelin, M.

    2014-01-01

    Roč. 305, June (2014), s. 674-682 ISSN 0169-4332 R&D Projects: GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : Inconel * Oxidation * High temperature * Oxygen plasma * Hydrogen plasma Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.711, year: 2014 https://www.sciencedirect.com/science/article/pii/S0169433214007119

  1. Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration

    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.

  2. Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration

    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

  3. Irradiation of cells by single and double pulses of high intensity radiation: oxygen sensitization and diffusion kinetics

    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.)

  4. Oxygen ordering and superconductivity in the high Tc superconductor YBa2Cu3O6+x

    Friis Poulsen, H.

    1991-12-01

    This report contains the result of an experimental and theoretical investigation of the oxygen ordering process in the High T c superconductor Y Ba 2 Cu 3 O 6+x . Neutron scattering is used in connection with in situ monitoring of the oxygen in-diffusion in a gas-volumetric equipment. Information on the variations of the structural phases, the twin domain sizes, the elastic forces, the chemical potential og oxygen as well as diffusion are provided. Using Monte Carlo simulations we find that a simple two-dimentional lattice gas model of the oxygen ordering process, the ASYNNNI model, gives an excellent description of the vast majority of these data. A systematic study of the relationship between the static and dynamic variations of the superconducting transition temperature, T c , and the corresponding variations of the low temperature oxygen ordering process is performed. Statistics from Monte Carlo simulations based on the ASYNNNI model are combined with experimental data from the literature. The combined static and dynamic analysis makes it evident that within a charge transfer model, a linear T c versus charge transfer relationship can only be rationalized if the description is based on extended coherent ordered domains and if the dynamic co-existence between the Ortho-I and the Ortho-II type of domains inherent to the ASYNNNI model is taken into account. A minimal model is proposed, where the total charge transfer is found as a weighted sum over the areas of the Ortho-I and the Ortho-II domains, and the minimal size of the two types of domains are given by a doubling og their unit cells in both directions. (au) 5 tabs., 35 ills., 108 refs

  5. Creep-fatigue life property of FBR high-temperature structural materials under tension-torsion loading and life evaluation method

    Ogata, Takashi; Nitta, Akito

    1994-01-01

    Creep-fatigue damage in high temperature structural components in a FBR progress under multiaxial stress condition depending on their operating conditions and configuration. Therefore, multiaxial stress effects on creep-fatigue damage evolution must be clarified to make precise creep-fatigue damage evaluation of these components. In this study, creep-fatigue tests in FBR high temperature materials such as SUS304, 316FR stainless steels and a modified 9Cr steel were conducted under biaxial stress subjecting tension-compression and torsion loading, in order to examine biaxial stress effects on failure mechanism and life property, and to discuss creep-fatigue life evaluation methods under biaxial stress. Main results obtained in this study are summarized as follows: 1. The main cracks under cyclic torsion loading propagated by shear mode in three materials. But intergranular failure was occurred in SUS304 and 316FR, and transgranular failure was observed in Mod.9Cr steel. 2. Nonlinear damage accumulation model proposed based on uniaxial creep-fatigue test results was extended to apply for creep-fatigue damage evaluation under biaxial stress state by considering the biaxial stress effects on fatigue and creep damage evolution. 3. It was confirmed that creep-fatigue life under biaxial stress could be predicted by the extended evaluation method with higher accuracy than existing methods. (author)

  6. MASH TEST NO. 3-10 OF A NON-PROPRIETARY, HIGH-TENSION CABLE MEDIAN BARRIER FOR USE IN 6H:1V V-DITCH (TEST NO. MWP-8)

    2017-05-10

    The Midwest States Pooled Fund Program has been developing a prototype design for a non-proprietary, high-tension cable median barrier for use in a 6H:1V V-ditch. This system incorporates four evenly spaced cables, Midwest Weak Posts (MWP) spaced at ...

  7. Highly sensitive fiber-optic oxygen sensor based on palladium tetrakis (4-carboxyphenyl)porphyrin doped in ormosil

    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

  8. Spontaneous tension haemopneumothorax.

    Patterson, Benjamin Oliver; Itam, Sarah; Probst, Fey

    2008-10-31

    We present a patient with sudden onset progressive shortness of breath and no history of trauma, who rapidly became haemodynamically compromised with a pneumothorax and pleural effusion seen on chest radiograph. He was treated for spontaneous tension pneumothorax but this was soon revealed to be a tension haemopneumothorax. He underwent urgent thoracotomy after persistent bleeding to explore an apical vascular abnormality seen on CT scanning. To our knowledge this is the first such case reported.Aetiology and current approach to spontaneous haemothorax are discussed briefly.

  9. Spontaneous tension haemopneumothorax

    Itam Sarah

    2008-10-01

    Full Text Available Abstract We present a patient with sudden onset progressive shortness of breath and no history of trauma, who rapidly became haemodynamically compromised with a pneumothorax and pleural effusion seen on chest radiograph. He was treated for spontaneous tension pneumothorax but this was soon revealed to be a tension haemopneumothorax. He underwent urgent thoracotomy after persistent bleeding to explore an apical vascular abnormality seen on CT scanning. To our knowledge this is the first such case reported. Aetiology and current approach to spontaneous haemothorax are discussed briefly.

  10. The role of oxygen-increased respirator in humans ascending to high altitude

    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.

  11. Highly Graphitic Carbon Nanofibers Web as a Cathode Material for Lithium Oxygen Batteries

    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.

  12. Oxygen sensing and conducted vasomotor responses in mouse cremaster arterioles in situ

    Ngo, Thuc Anh; Jensen, Lars Jørn; Riemann, Mads Achen

    2010-01-01

    .0 +/- 4.9 mum) when changing from high (PO(2) = 242.5 +/- 13.3 mm Hg) to low (PO(2) = 22.5 +/- 4.8 mm Hg) oxygen tension as seen in the intact cremaster circulation (DeltaD = 18.7 +/- 1.0 mum). Blockade of NO synthases by L: -NAME and adenosine receptors by DPCPX had no effects on vasomotor responses...... to low or high oxygen. Induction of localized low (PO(2) = 23.3 +/- 5.7 mmHg) or high (PO(2) = 300.0 +/- 25.7 mm Hg) oxygen tension caused vasodilatation or -constriction locally and at a site 1,000 mum upstream (distantly). Glibenclamide blocker of ATP-sensitive K(+) channels inhibited vasodilatation...... and -constriction to low (PO(2) = 16.0 +/- 6.4 mm Hg) and high (PO(2) = 337.4 +/- 12.8 mm Hg) oxygen tension. 1) ATP-sensitive K(+) channels seem to mediate, at least in part, vasodilatation and vasoconstriction to low and high oxygen tension; 2) Red blood cells are not necessary for inducing vasodilatation...

  13. Enhanced thermoelectric property of oxygen deficient nickel doped SnO2 for high temperature application

    Paulson, Anju; Sabeer, N. A. Muhammad; Pradyumnan, P. P.

    2018-04-01

    Motivated by the detailed investigation on the thermoelectric performance of oxide materials our work concentrated on the influence of acceptor dopants and defect density in the lattice plane for the enhancement of thermoelectric power. The series of Sn1‑x Nix O2 (0.01 ≤ x ≤ 0.05) compositions were prepared by solid state reaction mechanism and found that 3 atomic percentage Ni doped SnO2 can be considered as a good candidate due to its promising electrical and transport properties. Defect lattices were introduced in the sample and the deviation from oxygen stochiometry was ensured using photoluminescence measurement. High power factor was obtained for the 3 atomic percentage nickel doped SnO2 due to the effective number of charge carrier concentration and the depletion of oxygen rich layers. Defect centered and acceptor doped SnO2 lattice opens a new door for energy harvesting at higher temperatures.

  14. High-Flow Nasal Interface Improves Oxygenation in Patients Undergoing Bronchoscopy

    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.

  15. Investigation on the improved radiation hardness of silicon detectors with high oxygen concentration

    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

  16. New solution to the problem of the tension between the high-redshift and low-redshift measurements of the Hubble constant

    Bolejko, Krzysztof

    2018-01-01

    During my talk I will present results suggesting that the phenomenon of emerging spatial curvature could resolve the conflict between Planck's (high-redshift) and Riess et al. (low-redshift) measurements of the Hubble constant. The phenomenon of emerging spatial curvature is absent in the Standard Cosmological Model, which has a flat and fixed spatial curvature (small perturbations are considered in the Standard Cosmological Model but their global average vanishes, leading to spatial flatness at all times).In my talk I will show that with the nonlinear growth of cosmic structures the global average deviates from zero. As a result, the spatial curvature evolves from spatial flatness of the early universe to a negatively curved universe at the present day, with Omega_K ~ 0.1. Consequently, the present day expansion rate, as measured by the Hubble constant, is a few percent higher compared to the high-redshift constraints. This provides an explanation why there is a tension between high-redshift (Planck) and low-redshift (Riess et al.) measurements of the Hubble constant. In the presence of emerging spatial curvature these two measurements should in fact be different: high redshift measurements should be slightly lower than the Hubble constant inferred from the low-redshift data.The presentation will be based on the results described in arXiv:1707.01800 and arXiv:1708.09143 (which discuss the phenomenon of emerging spatial curvature) and on a paper that is still work in progress but is expected to be posted on arxiv by the AAS meeting (this paper uses mock low-redshift data to show that starting from the Planck's cosmological models (in the early universe) but with the emerging spatial curvature taken into account, the low-redshift Hubble constant should be 72.4 km/s/Mpc.

  17. Molecular mechanisms regulating oxygen transport and consumption in high altitude and hibernating mammals

    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...

  18. Combined special capsular tension ring and toric IOL implantation for management of post-DALK high regular astigmatism with subluxated traumatic cataract

    Asim Kumar Kandar

    2014-01-01

    Full Text Available We report a case of 18-year-old male who has undergone phacoemulsification with implantation of toric IOL (AcrySof IQ SN6AT9 after fixation of lens capsule with Cionni′s capsular tension ring (CTR for subluxated traumatic cataract with high astigmatism after deep anterior lamellar keratoplasty (DALK. He underwent right eye DALK for advanced keratoconus four years earlier. He had history of trauma one year later with displaced clear crystalline lens into  anterior chamber and graft dehiscence, which was repaired successfully. The graft survived, but patient developed cataract with subluxated lens, for which phacoemulsification with implantation of toric IOL was done. Serial  topography showed regular corneal astigmatism of -5.50 diopter (K 1 42.75 D @130°, K 2 48.25 D @40°. At 10-month follow-up, the patient has BCVA 20/30 with + 0.75 DS/- 1.75 DC @ 110°. The capsular bag is quite stable with well-centered IOL. Combination of Cionni′s ring with toric IOL could be a good option to manage such complex cases.

  19. Combined special capsular tension ring and toric IOL implantation for management of post-DALK high regular astigmatism with subluxated traumatic cataract.

    Kandar, Asim Kumar

    2014-07-01

    We report a case of 18-year-old male who has undergone phacoemulsification with implantation of toric IOL (AcrySof IQ SN6AT9) after fixation of lens capsule with Cionni's capsular tension ring (CTR) for subluxated traumatic cataract with high astigmatism after deep anterior lamellar keratoplasty (DALK). He underwent right eye DALK for advanced keratoconus four years earlier. He had history of trauma one year later with displaced clear crystalline lens into  anterior chamber and graft dehiscence, which was repaired successfully. The graft survived, but patient developed cataract with subluxated lens, for which phacoemulsification with implantation of toric IOL was done. Serial  topography showed regular corneal astigmatism of -5.50 diopter (K 1 42.75 D @130°, K 2 48.25 D @40°). At 10-month follow-up, the patient has BCVA 20/30 with + 0.75 DS/- 1.75 DC @ 110°. The capsular bag is quite stable with well-centered IOL. Combination of Cionni's ring with toric IOL could be a good option to manage such complex cases.

  20. Metal-free and Oxygen-free Graphene as Oxygen Reduction Catalysts for Highly Efficient Fuel Cells

    2013-06-30

    analysis was carried out by a TA instrument with a heating rate of 10 °C in N2. The Raman spectra were collected on a Raman spectrometer (Renishaw...kinematics viscosity for KOH (v = 0.01 cm 2 s -1 ) and CO2 is concentration of O2 in the solution (CO2 = 1.2 × 10 -6 mol cm -3 ). The constant 0.2 is...functionalizing graphene to impart electrocatalytic activity for oxygen reduction reaction (ORR) in fuel cells. Raman and X-ray photoelectron spectroscopic

  1. High Flow Nasal Cannula Oxygen Therapy can be used safely in the general paediatric ward using Paediatric Early Warning Scores

    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

  2. Electrochemical catalytic reforming of oxygenated-organic compounds: a highly efficient method for production of hydrogen from bio-oil.

    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.

  3. Effect of high-oxygen atmosphere packaging on oxidative stability and sensory quality of two chicken muscles during chill storage

    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...

  4. Tension-filled Governance?

    Celik, Tim Holst

    on the statesituated tension-filled functional relationship between legitimation and accumulation, the study both historically and theoretically reworks this approach and reapplies it for the post-1970s/1990s governance period. It asks whether and to what extent governance has served as a distinctive post- 1970s/1990s...

  5. Rein tension during canter

    Egenvall, Agneta; Eisersiö, Marie; Rhodin, Marie; van Weeren, P.R.; Roepstorff, Lars

    2015-01-01

    Riders generally use reins as a means for communication with the horse. At present, the signalling pattern is poorly understood. The aim of this study was to illustrate and analyse the rein tension patterns in a number of rider/horse combinations across a variety of exercises in the canter gait. Our

  6. Tension waves in tethered satellite cables

    Lallman, F. J.

    1984-01-01

    A one-degree-of-freedom simulation of the Tethered Satellite System (TSS) was programmed using a distributed system model of the tether based on the one-dimensional wave equation. This model represents the time varying tension profile along the tether as the sum of two traveling waves of tension moving in opposite directions. A control loop was devised which combines a deployment rate command with the measured tension at the deployer to produce a smooth, stable rate of deployment of the subsatellite. Simulation results show a buildup of periodic bursts of high frequency oscillation in tension. This report covers the mathematical modelling and simulation results and explains the reason for the observed oscillations. The design of a possible vibration damping device is discussed.

  7. High cell density fed-batch fermentations for lipase production: feeding strategies and oxygen transfer.

    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.

  8. Electrochemically fabricated polypyrrole-cobalt-oxygen coordination complex as high-performance lithium-storage materials.

    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.

  9. Hyperbaric Oxygen Therapy as a Sole Agent Is Not Immunosuppressant in a Highly Immunogenic Mouse Model

    Adam Gassas

    2011-01-01

    Full Text Available Background. Hyperbaric oxygen (HBO therapy, which is used for many conditions, may also have immunosuppressive effects and could be used for prevention or treatment of graft-versus-host disease (GvHD. If HBO is immunosuppressant, then we hypothesize that HBO therapy will delay the T-cell mediated skin graft rejection. Methods. C57/BL6 black-coated (H2B mice received skin graft from CBA (H2D white-coated mice. Mice were treated with either 19 session of 240 kpa oxygen or 29 session of 300 kpa oxygen, for 90 minutes. Mice were housed either 4 per cage or separately, to prevent friction and mechanical factors that may affect graft survival. Skin grafts were assessed daily. Results. There was no difference in length of graft survival between mice that received either regimens of HBO therapy and mice that did not receive HBO therapy. Conclusions. HBO therapy, as a sole agent, did not delay skin graft rejection in a highly immunogenic mouse model.

  10. 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.

  11. 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.

  12. Formation of SIMOX–SOI structure by high-temperature oxygen implantation

    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.

  13. Supplemental Oxygen During High-Intensity Exercise Training in Nonhypoxemic Chronic Obstructive Pulmonary Disease.

    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.

  14. The value of high-flow nasal cannula oxygen therapy after extubation in patients with acute respiratory failure

    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.

  15. Coulomb string tension, asymptotic string tension, and the gluon chain

    Greensite, Jeff; Szczepaniak, Adam P.

    2014-01-01

    We compute, via numerical simulations, the non-perturbative Coulomb potential of pure SU(3) gauge theory in Coulomb gauge. We find that that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

  16. Quantification of oxygen and carbon in high Tc superconducting films by (α,α) elastic resonance technique

    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)

  17. Estimated Trans-Lamina Cribrosa Pressure Differences in Low-Teen and High-Teen Intraocular Pressure Normal Tension Glaucoma: The Korean National Health and Nutrition Examination Survey.

    Si Hyung Lee

    Full Text Available To investigate the association between estimated trans-lamina cribrosa pressure difference (TLCPD and prevalence of normal tension glaucoma (NTG with low-teen and high-teen intraocular pressure (IOP using a population-based study design.A total of 12,743 adults (≥ 40 years of age who participated in the Korean National Health and Nutrition Examination Survey (KNHANES from 2009 to 2012 were included. Using a previously developed formula, cerebrospinal fluid pressure (CSFP in mmHg was estimated as 0.55 × body mass index (kg/m2 + 0.16 × diastolic blood pressure (mmHg-0.18 × age (years-1.91. TLCPD was calculated as IOP-CSFP. The NTG subjects were divided into two groups according to IOP level: low-teen NTG (IOP ≤ 15 mmHg and high-teen NTG (15 mmHg < IOP ≤ 21 mmHg groups. The association between TLCPD and the prevalence of NTG was assessed in the low- and high-teen IOP groups.In the normal population (n = 12,069, the weighted mean estimated CSFP was 11.69 ± 0.04 mmHg and the weighted mean TLCPD 2.31 ± 0.06 mmHg. Significantly higher TLCPD (p < 0.001; 6.48 ± 0.27 mmHg was found in the high-teen NTG compared with the normal group. On the other hand, there was no significant difference in TLCPD between normal and low-teen NTG subjects (p = 0.395; 2.31 ± 0.06 vs. 2.11 ± 0.24 mmHg. Multivariate logistic regression analysis revealed that TLCPD was significantly associated with the prevalence of NTG in the high-teen IOP group (p = 0.006; OR: 1.09; 95% CI: 1.02, 1.15, but not the low-teen IOP group (p = 0.636. Instead, the presence of hypertension was significantly associated with the prevalence of NTG in the low-teen IOP group (p < 0.001; OR: 1.65; 95% CI: 1.26, 2.16.TLCPD was significantly associated with the prevalence of NTG in high-teen IOP subjects, but not low-teen IOP subjects, in whom hypertension may be more closely associated. This study suggests that the underlying mechanisms may differ between low-teen and high-teen NTG patients.

  18. A Case of Pneumothorax due to High-Flow Nasal Cannula Oxygen Therapy

    Çapan Konca

    2017-08-01

    Full Text Available Invasive and noninvasive mechanical ventilation (MV applications are used for patients with respiratory insufficiency. Noninvasive MV has been increasingly used in pediatric intensive care units in recent years. For this purpose, high-flow nasal cannula (HFNC oxygen therapy is a treatment method that has been increasingly used. Despite the numerous studies reporting the advantages of this method, there are also a few studies reporting that undesirable conditions can be observed. In this paper, in order to contribute to the literature, we present a 3-month-old baby who developed pneumothorax during HFNC implementation.

  19. Direct imaging of fractional oxygen Oδ in Hg-based high-Tc superconductors

    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

  20. Magnetization and flux pinning in high-Tc cuprates: Irradiated and oxygen deficient materials

    Thompson, J.R.; Civale, L.; Marwick, A.D.; Holtzberg, F.

    1992-11-01

    This work surveys recent studies of the intragrain current density J and vortex pinning in high Tc superconductors. Materials include Y 1 Ba 2 Cu 3 O 7-δ and Bi 2 Sr 2 Ca 1 Cu 2 O 8 single crystals and aligned polycrystals. To probe the flux pinning, we modified the strength, number, and morphology of defects. Varying the oxygen content (7-δ) in YBa 2 Cu 3 O 7-δ or irradiating the materials with ions, having either light or heavy masses, gives systematic changes in the character of the all-important defects

  1. 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

  2. Maximal exercise and muscle oxygen extraction in acclimatizing lowlanders and high altitude natives

    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...

  3. Determination of oxygen content in high T/sub c/ superconductors by a charged particle activation method

    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

  4. High-performance a -Si/c-Si heterojunction photoelectrodes for photoelectrochemical oxygen and hydrogen evolution

    Wang, Hsin Ping

    2015-05-13

    Amorphous Si (a-Si)/crystalline Si (c-Si) heterojunction (SiHJ) can serve as highly efficient and robust photoelectrodes for solar fuel generation. Low carrier recombination in the photoelectrodes leads to high photocurrents and photovoltages. The SiHJ was designed and fabricated into both photoanode and photocathode with high oxygen and hydrogen evolution efficiency, respectively, by simply coating of a thin layer of catalytic materials. The SiHJ photoanode with sol-gel NiOx as the catalyst shows a current density of 21.48 mA/cm2 at the equilibrium water oxidation potential. The SiHJ photocathode with 2 nm sputter-coated Pt catalyst displays excellent hydrogen evolution performance with an onset potential of 0.640 V and a solar to hydrogen conversion efficiency of 13.26%, which is the highest ever reported for Si-based photocathodes. © 2015 American Chemical Society.

  5. Microbial nar-GFP cell sensors reveal oxygen limitations in highly agitated and aerated laboratory-scale fermentors

    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.

  6. Rosemary and oxygen scavenger in active packaging for prevention of high-pressure induced lipid oxidation in pork patties

    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...

  7. 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.

  8. Electrochemically Formed Ultrafine Metal Oxide Nanocatalysts for High-Performance Lithium–Oxygen Batteries

    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.

  9. High-sensitivity imaging method of singlet oxygen and superoxide anion in photodynamic and sonodynamic actions

    Xing, Da; He, Yonghong; Hao, Min; Chen, Qun

    2004-07-01

    A novel method of photodynamic diagnosis (PDD) of cancer mediated by chemiluminescence (CL) probe is presented. The mechanism for photodynamic therapy (PDT) involves reactive oxygen species (ROS), such as singlet oxygen (1O2) and superoxide (O2-), generated by during the photochemical process. Both 1O2 and O2- can react with Cypridina luciferin analogue (FCLA), a highly selective CL probe for detecting the ROS. Chemiluminescence from the reaction of FCLA with the ROS, at about 530 nm, was detected by a highly sensitive ICCD system. The CL was markedly inhibited by the addition of 10 mmol/L sodium azide (NaN3) in a sample solution. Similar phenomena, with lesser extents of changes, were observed at the additions of 10 μmol/L superoxide dismutase (SOD), 10 mmol/L mannitol, and 100 μg/mL catalase, respectively. This indicates that the detected CL signals were mainly from ROS generated during the photosensitization reactions. Also, the chemiluminescence method was used to detect the ROS during sonodynamic action, both in vitro and in vivo. ROS formation during sonosensitizations of HpD and ATX-70 were detected using our newly-developed imaging technique, in real time, on tumor bearing animals. This method can provide a new means in clinics for tumor diagnosis.

  10. Surface strontium enrichment on highly active perovskites for oxygen electrocatalysis in solid oxide fuel cells

    Crumlin, Ethan J.; Mutoro, Eva; Liu, Zhi; Grass, Michael E.; Biegalski, Michael D.; Lee, Yueh-Lin; Morgan, Dane; Christen, Hans M.; Bluhm, Hendrik; Shao-Horn, Yang

    2012-01-01

    Perovskite oxides have high catalytic activities for oxygen electrocatalysis competitive to platinum at elevated temperatures. However, little is known about the oxide surface chemistry that influences the activity near ambient oxygen partial pressures, which hampers the design of highly active catalysts for many clean-energy technologies such as solid oxide fuel cells. Using in situ synchrotron-based, ambient pressure X-ray photoelectron spectroscopy to study the surface chemistry changes, we show that the coverage of surface secondary phases on a (001)-oriented La 0.8Sr 0.2CoO 3-δ (LSC) film becomes smaller than that on an LSC powder pellet at elevated temperatures. In addition, strontium (Sr) in the perovskite structure enriches towards the film surface in contrast to the pellet having no detectable changes with increasing temperature. We propose that the ability to reduce surface secondary phases and develop Sr-enriched perovskite surfaces of the LSC film contributes to its enhanced activity for O 2 electrocatalysis relative to LSC powder-based electrodes. © 2012 The Royal Society of Chemistry.

  11. Facile synthesis of high strength hot-water wood extract films with oxygen-barrier performance

    Chen, Ge-Gu; Fu, Gen-Que; Wang, Xiao-Jun; Gong, Xiao-Dong; Niu, Ya-Shuai; Peng, Feng; Yao, Chun-Li; Sun, Run-Cang

    2017-01-01

    Biobased nanocomposite films for food packaging with high mechanical strength and good oxygen-barrier performance were developed using a hot-water wood extract (HWE). In this work, a facile approach to produce HWE/montmorillonite (MMT) based nanocomposite films with excellent physical properties is described. The focus of this study was to determine the effects of the MMT content on the structure and mechanical properties of nanocomposites and the effects of carboxymethyl cellulose (CMC) on the physical properties of the HWE-MMT films. The experimental results suggested that the intercalation of HWE and CMC in montmorillonite could produce compact, robust films with a nacre-like structure and multifunctional characteristics. This results of this study showed that the mechanical properties of the film designated FCMC0.05 (91.5 MPa) were dramatically enhanced because the proportion of HWE, MMT and CMC was 1:1.5:0.05. In addition, the optimized films exhibited an oxygen permeability below 2.0 cm3 μm/day·m2·kPa, as well as good thermal stability due to the small amount of CMC. These results provide a comprehensive understanding for further development of high-performance nanocomposites which are based on natural polymers (HWE) and assembled layered clays (MMT). These films offer great potential in the field of sustainable packaging.

  12. The use of high-flow nasal oxygen in COPD patients

    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.

  13. Modelling of zircaloy-4 degradation in oxygen and nitrogen mixtures at high temperature

    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

  14. An fMRI study on variation of visuospatial cognitive performance of young male due to highly concentrated oxygen administration

    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.

  15. Oxygen, nitric oxide and articular cartilage

    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.

  16. High-Flow Nasal Cannula versus Conventional Oxygen Therapy in Children with Respiratory Distress.

    Sitthikarnkha, Punthila; Samransamruajkit, Rujipat; Prapphal, Nuanchan; Deerojanawong, Jitladda; Sritippayawan, Suchada

    2018-05-01

    The aim of this study is to determine the clinical efficacy of high-flow nasal cannula (HFNC) therapy compared with conventional oxygen therapy in children presented with respiratory distress. This was a randomized controlled study. Infants and children aged between 1 month to 5 years who were admitted to our tertiary referral center for respiratory distress (July 1, 2014 to March 31, 2015) and met the inclusion criteria were recruited. Infants and children hospitalized with respiratory distress were randomized into two groups of interventions. All clinical data, for example, respiratory score, pulse rate, and respiratory rate were recorded. The results were subsequently analyzed. A total of 98 respiratory distress children were enrolled during the study period. Only 4 children (8.2%) failed in HFNC therapy, compared with 10 children (20.4%) in conventional oxygen therapy group ( P = 0.09). After adjusted for body weight, underlying diseases, and respiratory distress score, there was an 85% reduction in the odds of treatment failure in HFNC therapy group (adjusted odds ratio 0.15, 95% confidence interval 0.03-0.66, P = 0.01). Most children in HFNC therapy group had significant improvement in clinical respiratory score, heart rate, and respiratory rate at 240, 360, and 120 min compared with conventional oxygen therapy ( P = 0.03, 0.04, and 0.03). HFNC therapy revealed a potential clinical advantage in management children hospitalized with respiratory distress compared with conventional respiratory therapy. The early use of HFNC in children with moderate-to-severe respiratory distress may prevent endotracheal tube intubation. TCTR 20170222007.

  17. Deep Nitrate Deficit Observed in the Highly Oxygenated East/Japan Sea and Its Possible Cause

    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.

  18. High flow nasal cannula oxygen therapy, work in progress in respiratory critical care.

    Schreiber, Annia; DI Marco, Fabiano; Braido, Fulvio; Solidoro, Paolo

    2016-12-01

    After a planned extubation, the re-occurrence of acute respiratory distress needing the restoration of invasive mechanical support is a severe phenomenon associated with several important consequences, including increased morbidity, Intensive Care Unit mortality, and an enormous financial burden. So far, the most commonly used techniques to ameliorate gas exchange in the postextubation period were low-flow oxygen therapy and non-invasive ventilation (NIV). High flows through nasal cannulae (HFNC) is a system which allows increased CO2 wash-out of anatomical dead space, positive nasopharyngeal pressure, a relatively constant FiO2, and an improvement of mucociliary function. In a recently published paper by Hernandez et al. HFNC therapy, compared in the postextubation period to standard oxygen in patients at low risk of re-intubation, was associated with a lower re-intubation rate within 72 hours of extubation, with no evidence of any delays in re-intubation which may prove fatal, as previously reported in the context of NIV. Despite yielding some useful starting points and positive results with HFNC, some discrepancies have emerged in the findings of the studies in this field. As we await further more homogeneous and enlightening studies, at present we can only affirm that HFNC seems to be a useful means to prevent and treat postextubation hypoxemia. In fact no harmful or adverse effects related to HFNC emerged in any of the studies and globally, it was associated with better comfort and tolerance compared with NIV, which justifies its use as a first alternative to standard oxygen therapy.

  19. 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.

  20. Hydrogen/Oxygen Reactions at High Pressures and Intermediate Temperatures: Flow Reactor Experiments and Kinetic Modeling

    Hashemi, Hamid; Christensen, Jakob Munkholt; Glarborg, Peter

    A series of experimental and numerical investigations into hydrogen oxidation at high pressures and intermediate temperatures has been conducted. The experiments were carried out in a high pressure laminar flow reactor at 50 bar pressure and a temperature range of 600–900 K. The equivalence ratio......, the mechanism is used to simulate published data on ignition delay time and laminar burning velocity of hydrogen. The flow reactor results show that at reducing, stoichiometric, and oxidizing conditions, conversion starts at temperatures of 750–775 K, 800–825 K, and 800–825 K, respectively. In oxygen atmosphere......, ignition occurs at the temperature of 775–800 K. In general, the present model provides a good agreement with the measurements in the flow reactor and with recent data on laminar burning velocity and ignition delay time....

  1. 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.

  2. Radial transport of high-energy oxygen ions into the deep inner magnetosphere observed by Van Allen Probes

    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.

  3. Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration.

    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.

  4. Characterization and consequences of intermittent sediment oxygenation by macrofauna: interpretation of high-resolution data sets

    Meile, C. D.; Dwyer, I.; Zhu, Q.; Polerecky, L.; Volkenborn, N.

    2017-12-01

    Mineralization of organic matter in marine sediments leads to the depletion of oxygen, while activities of infauna introduce oxygenated seawater to the subsurface. In permeable sediments solutes can be transported from animals and their burrows into the surrounding sediment through advection over several centimeters. The intermittency of pumping leads to a spatially heterogeneous distribution of oxidants, with the temporal dynamics depending on sediment reactivity and activity patterns of the macrofauna. Here, we present results from a series of experiments in which these dynamics are studied at high spatial and temporal resolution using planar optodes. From O2, pH and pCO2 optode data, we quantify rates of O2 consumption and dissolved inorganic carbon production, as well alkalinity dynamics, with millimeter-scale resolution. Simulating intermittent irrigation by imposed pumping patterns in thin aquaria, we derive porewater flow patterns, which together with the production and consumption rates cause the chemical distributions and the establishment of reaction fronts. Our analysis thus establishes a quantitative connection between the locally dynamic redox conditions relevant for biogeochemical transformations and macroscopic observations commonly made with sediment cores.

  5. Calculation of Oxygen Fugacity in High Pressure Metal-Silicate Experiments and Comparison to Standard Approaches

    Righter, K.; Ghiorso, M.

    2009-01-01

    Calculation of oxygen fugacity in high pressure and temperature experiments in metal-silicate systems is usually approximated by the ratio of Fe in the metal and FeO in the silicate melt: (Delta)IW=2*log(X(sub Fe)/X(sub FeO)), where IW is the iron-wustite reference oxygen buffer. Although this is a quick and easy calculation to make, it has been applied to a huge variety of metallic (Fe- Ni-S-C-O-Si systems) and silicate liquids (SiO2, Al2O3, TiO2, FeO, MgO, CaO, Na2O, K2O systems). This approach has surely led to values that have little meaning, yet are applied with great confidence, for example, to a terrestrial mantle at "IW-2". Although fO2 can be circumvented in some cases by consideration of Fe-M distribution coefficient, these do not eliminate the effects of alloy or silicate liquid compositional variation, or the specific chemical effects of S in the silicate liquid, for example. In order to address the issue of what the actual value of fO2 is in any given experiment, we have calculated fO2 from the equilibria 2Fe (metal) + SiO2 (liq) + O2 = Fe2SiO4 (liq).

  6. Oxygen diffusion kinetics and reactive lifetimes in bacterial and mammalian cells irradiated with nanosecond pulses of high intensity electrons

    Epp, E.R.; Weiss, H.; Ling, C.C.; Djordjevic, B.; Kessaris, N.D.

    1975-01-01

    Experiaments have been designed to gain information on the lifetime of oxygen-sensitive species suspected to be produced in critical molecules in irradiated cells and on the time-diffusion of oxygen in cells. An approach developed in this laboratory involves the delivery of two high intensity electron pulses each of 3 ns duration to a thin layer of cells equilibrated with a known concentration of oxygen. The first pulse serves to render the cells totally anoxic by the radiochemical depletion of oxygen; the second is delivered at a time electronically delayed after the first allowing for diffusion of oxygen during this time. Under these conditions the radiosensitivity of E coli B/r has been measured over six decades of interpulse time. Cellular time-diffusion curves constructed from the measurements show that oxygen establishes its sensitizing effect within 10 -4 s after the creation of intracellular anoxia establishing this time as an upper limit to the lifetime of the species. Unusual behaviour of the diffusion curve observed for longer delay times can be explained by a model wherein it is postulated that a radiation-induced inhibiting agent slows down diffusion. Application of this model to the experimental data yields a value of 0.4x10 -5 cm 2 s -1 for the cellular oxygen diffusion coefficient. Similar experiments recently carried out for Serratia marcescens will also be described. The oxygen effect in cultured HeLa cells exposed to single short electron pulses has been examined over a range of oxygen concentrations. A family of breaking survival curves was obtained similar to those previously measured for E coli B/r by this laboratory. The data appear to be reasonably consistent with a physicochemical mechanism involving the radiochemical depletion of oxygen previously invoked for bacteria. (author)

  7. 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.

  8. High salt-induced excess reactive oxygen species production resulted in heart tube malformation during gastrulation.

    Gao, Lin-Rui; Wang, Guang; Zhang, Jing; Li, Shuai; Chuai, Manli; Bao, Yongping; Hocher, Berthold; Yang, Xuesong

    2018-09-01

    An association has been proved between high salt consumption and cardiovascular mortality. In vertebrates, the heart is the first functional organ to be formed. However, it is not clear whether high-salt exposure has an adverse impact on cardiogenesis. Here we report high-salt exposure inhibited basement membrane breakdown by affecting RhoA, thus disturbing the expression of Slug/E-cadherin/N-cadherin/Laminin and interfering with mesoderm formation during the epithelial-mesenchymal transition(EMT). Furthermore, the DiI + cell migration trajectory in vivo and scratch wound assays in vitro indicated that high-salt exposure restricted cell migration of cardiac progenitors, which was caused by the weaker cytoskeleton structure and unaltered corresponding adhesion junctions at HH7. Besides, down-regulation of GATA4/5/6, Nkx2.5, TBX5, and Mef2c and up-regulation of Wnt3a/β-catenin caused aberrant cardiomyocyte differentiation at HH7 and HH10. High-salt exposure also inhibited cell proliferation and promoted apoptosis. Most importantly, our study revealed that excessive reactive oxygen species(ROS)generated by high salt disturbed the expression of cardiac-related genes, detrimentally affecting the above process including EMT, cell migration, differentiation, cell proliferation and apoptosis, which is the major cause of malformation of heart tubes. © 2018 Wiley Periodicals, Inc.

  9. High energy-intensity atomic oxygen beam source for low earth orbit materials degradation studies

    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

  10. Tension-type headache

    Bendtsen, Lars; Jensen, Rigmor; Bendtsen, Lars

    2009-01-01

    The substantial societal and individual burdens associated with tension-type headache (TTH) constitute a previously overlooked major public health issue. TTH is prevalent, affecting up to 78% of the general population, and 3% suffer from chronic TTH. Pericranial myofascial nociception probably...... is important for the pathophysiology of episodic TTH, whereas sensitization of central nociceptive pathways seems responsible for the conversion of episodic to chronic TTH. Headache-related disability usually can be reduced by identification of trigger factors combined with nonpharmacologic and pharmacologic...... treatments, but effective treatment modalities are lacking. Benefits can be gained by development of specific and effective treatment strategies....

  11. Effect of high-oxygen and high-carbon-dioxide atmospheres on strawberry flavor and other quality traits.

    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.

  12. Monitoring of crack growth and crack mouth opening displacement in compact tension specimens at high temperatures : Development and implementation of the Direct Current Potential Drop (DCPD) method

    Malmqvist, Philip

    2016-01-01

    The mechanical engineering department at the University of Idaho is conducting a project with the purpose of developing a complete system for investigating creep-, creep-fatigue- and fatigue properties of metallic materials at elevated temperatures up to 650 ˚C with Compact Tension (CT) specimens. Considerable efforts have been made to study and understand these phenomena, although numerous problems still exist. It is important to explore more extensively the complicated phenomena of creep, f...

  13. Comparison of fracture toughness values of normal and high strength concrete determined by three point bend and modified disk-shaped compact tension specimens

    Seitl, Stanislav; Ríjos, J. D.; Cifuentes, H.

    2017-01-01

    Roč. 11, č. 42 (2017), s. 56-65 ISSN 1971-8993 R&D Projects: GA ČR(CZ) GA16-18702S; GA MŠk LM2015069 Institutional support: RVO:68081723 Keywords : Concrete * Stress intensity factors * T-stress * Compact tension test * Fracture behavior * Fracture toughness Subject RIV: JL - Materials Fatigue, Friction Mechanics OBOR OECD: Audio engineering, reliability analysis

  14. High Precision Continuous and Real-Time Measurement of Atmospheric Oxygen Using Cavity Ring-Down Spectroscopy.

    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.

  15. Kinetics of the high temperature oxygen exchange reaction on {sup 238}PuO{sub 2} powder

    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.

  16. Microstructure Characterization of WCCo-Mo Based Coatings Produced Using High Velocity Oxygen Fuel

    Serkan Islak

    2015-12-01

    Full Text Available The present study has been carried out in order to investigate the microstructural properties of WCCo-Mo composite coatings deposited onto a SAE 4140 steel substrate by high velocity oxygen fuel (HVOF thermal spray. For this purpose, the Mo quantity added to the WCCo was changed as 10, 20, 30 and 40 wt. % percents. The coatings are compared in terms of their phase composition, microstructure and hardness. Phase compound and microstructure of coating layers were examined using X-ray diffractometer (XRD and scanning electron microscope (SEM. XRD results showed that WCCo-Mo composite coatings were mainly composed of WC, W2C, Co3W3C, Mo2C, MoO2, Mo and Co phases. The average hardness of the coatings increased with increasing Mo content.

  17. A high-performance mesoporous carbon supported nitrogen-doped carbon electrocatalyst for oxygen reduction reaction

    Xu, Jingjing; Lu, Shiyao; Chen, Xu; Wang, Jianan; Zhang, Bo; Zhang, Xinyu; Xiao, Chunhui; Ding, Shujiang

    2017-12-01

    Investigating low-cost and highly active electrocatalysts for oxygen reduction reactions (ORR) is of crucial importance for energy conversion and storage devices. Herein, we design and prepare mesoporous carbon supported nitrogen-doped carbon by pyrolysis of polyaniline coated on CMK-3. This electrocatalyst exhibits excellent performance towards ORR in alkaline media. The optimized nitrogen-doped mesoporous electrocatalyst show an onset potential (E onset) of 0.95 V (versus reversible hydrogen electrode (RHE)) and half-wave potential (E 1/2) of 0.83 V (versus RHE) in 0.1 M KOH. Furthermore, the as-prepared catalyst presents superior durability and methanol tolerance compared to commercial Pt/C indicating its potential applications in fuel cells and metal-air batteries.

  18. Pt Monolayer Shell on Nitrided Alloy Core—A Path to Highly Stable Oxygen Reduction Catalyst

    Jue Hu

    2015-07-01

    Full Text Available The inadequate activity and stability of Pt as a cathode catalyst under the severe operation conditions are the critical problems facing the application of the proton exchange membrane fuel cell (PEMFC. Here we report on a novel route to synthesize highly active and stable oxygen reduction catalysts by depositing Pt monolayer on a nitrided alloy core. The prepared PtMLPdNiN/C catalyst retains 89% of the initial electrochemical surface area after 50,000 cycles between potentials 0.6 and 1.0 V. By correlating electron energy-loss spectroscopy and X-ray absorption spectroscopy analyses with electrochemical measurements, we found that the significant improvement of stability of the PtMLPdNiN/C catalyst is caused by nitrogen doping while reducing the total precious metal loading.

  19. 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.

  20. Radiation losses from oxygen and iron impurities in a high temperature plasma

    Breton, C.; Michelis, C. de; Mattioli, M.

    1976-06-01

    Radiation and ionization losses due to impurities present in a high temperature plasma have been calculated for a light element (oxygen), which is completely stripped in the core of existing Tokamak discharges, and a heavy one (iron), which is only partially stripped. Two extreme cases have been treated: in the first one coronal equilibrium is reached; the radiated power is then equal to the product of the electron density, the impurity density, and a function of the electron temperature; in the second one impurities recycle with a constant radial velocity v 0 in a background plasma; radiation and ionization losses are proportional to the impurity flux and are a decreasing function of the diffusion velocity. The results presented can be used to evaluate losses in a practical case [fr

  1. Tooth enamel oxygen "isoscapes" show a high degree of human mobility in prehistoric Britain.

    Pellegrini, Maura; Pouncett, John; Jay, Mandy; Pearson, Mike Parker; Richards, Michael P

    2016-10-07

    A geostatistical model to predict human skeletal oxygen isotope values (δ 18 O p ) in Britain is presented here based on a new dataset of Chalcolithic and Early Bronze Age human teeth. The spatial statistics which underpin this model allow the identification of individuals interpreted as 'non-local' to the areas where they were buried (spatial outliers). A marked variation in δ 18 O p is observed in several areas, including the Stonehenge region, the Peak District, and the Yorkshire Wolds, suggesting a high degree of human mobility. These areas, rich in funerary and ceremonial monuments, may have formed focal points for people, some of whom would have travelled long distances, ultimately being buried there. The dataset and model represent a baseline for future archaeological studies, avoiding the complex conversions from skeletal to water δ 18 O values-a process known to be problematic.

  2. Tooth enamel oxygen “isoscapes” show a high degree of human mobility in prehistoric Britain

    Pellegrini, Maura; Pouncett, John; Jay, Mandy; Pearson, Mike Parker; Richards, Michael P.

    2016-10-01

    A geostatistical model to predict human skeletal oxygen isotope values (δ18Op) in Britain is presented here based on a new dataset of Chalcolithic and Early Bronze Age human teeth. The spatial statistics which underpin this model allow the identification of individuals interpreted as ‘non-local’ to the areas where they were buried (spatial outliers). A marked variation in δ18Op is observed in several areas, including the Stonehenge region, the Peak District, and the Yorkshire Wolds, suggesting a high degree of human mobility. These areas, rich in funerary and ceremonial monuments, may have formed focal points for people, some of whom would have travelled long distances, ultimately being buried there. The dataset and model represent a baseline for future archaeological studies, avoiding the complex conversions from skeletal to water δ18O values-a process known to be problematic.

  3. Highly oxygenated lanostane-type triterpenoids and their bioactivity from the fruiting body of Ganoderma gibbosum.

    Pu, De-Bing; Zheng, Xi; Gao, Jun-Bo; Zhang, Xing-Jie; Qi, Yan; Li, Xiao-Si; Wang, Yong-Mei; Li, Xiao-Nian; Li, Xiao-Li; Wan, Chun-Ping; Xiao, Wei-Lie

    2017-06-01

    Eight new highly oxygenated lanostane triterpenes, gibbosic acids A-H (1-8), along with three known ones (9-11), were isolated from the fruiting body of Ganoderma gibbosum. The structures of new isolates were assigned by NMR and HRESIMS experiments. The absolute configurations of 1 were further confirmed by single crystal X-ray diffraction data and computational ECD methods. Immunoregulatory effect and anti-inflammatory activities of these compounds were screened in murine lymphocyte proliferation assay and in lipopolysaccharide (LPS)-stimulated RAW-264.7 macrophages, respectively. Compound 2 exhibited immunostimulatory effect both in lymphocyte proliferation assay without any induction and ConA-induced mitogenic activity of T-lymphocyte, and the proportion of lymphocyte proliferation at the concentration of 0.1μM are 20.01% and 21.40%, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Clinical evidence on high flow oxygen therapy and active humidification in adults

    C. Gotera

    2013-09-01

    Full Text Available 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. Resumo: Recentemente, uma alternativa à oxigenoterapia convencional tem recebido atenção crescente: trata-se da oxigenoterapia humidificada de alto débito com cânulas nasais (HFNC. Um número de efeitos fisiológicos têm sido descritos: «lavagem» do espaço morto faríngeo, redução da resistência da nasofarige, efeito tipo «CPAP», recrutamento alveolar, maior humidificação, maior conforto e melhor tolerância do doente, melhor controle do FiO2 e do «clearance» mucociliar. A experiência com HFNC em adultos ainda é limitada e de momento não há «guidelines» para o seu uso. Neste artigo revemos a evidência existente do uso da HFNC em adultos, as suas vantagens, limitações e a literatura mais recente sobre as suas aplicações clínicas. Mais investigação será necessária para determinar os efeitos a longo prazo desta terapêutica e identificar quais as populações em que é mais benéfica. Keywords: High flow nasal cannula, Non-invasive ventilation, Gas exchange, Respiratory

  5. Synthesis of highly active and dual-functional electrocatalysts for methanol oxidation and oxygen reduction reactions

    Zhao, Qi; Zhang, Geng; Xu, Guangran; Li, Yingjun [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Liu, Baocang [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Gong, Xia [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Zheng, Dafang [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Zhang, Jun [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Wang, Qin, E-mail: qinwang@imu.edu.cn [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China)

    2016-12-15

    Graphical abstract: Ternary RuMPt (M = Fe, Co, Ni, and Cu) nanodendrities (NDs) catalysts, are successfully synthesized by using a facile method. The as-obtained ternary catalysts manifest superior catalytic activity and stability both in terms of surface and mass specific activities toward the methanol oxidation and oxygen reduction reactions, as compared to the binary catalysts and the commercial Pt/C catalysts. - Highlights: • Ternary RuMPt catalysts are synthesized by using a facile method. • The catalysts manifest superior catalytic activity towards the MOR and ORR. • High activities are attributed to enhanced electron density and synergistic effects. - Abstract: The promising Pt-based ternary catalyst is crucial for polymer electrolyte membrane fuel cells (PEMFCs) due to improving catalytic activity and durability for both methanol oxidation reaction and oxygen reduction reaction. In this work, a facile strategy is used for the synthesis ternary RuMPt (M = Fe, Co, Ni, and Cu) nanodendrities catalysts. The ternary RuMPt alloys exhibit enhanced specific and mass activity, positive half-wave potential, and long-term stability, compared with binary Pt-based alloy and the commercial Pt/C catalyst, which is attributed to the high electron density and upshifting of the d-band center for Pt atoms, and synergistic catalytic effects among Pt, M, and Ru atoms by introducing a transition metal. Impressively, the ternary RuCoPt catalyst exhibits superior mass activity (801.59 mA mg{sup −1}) and positive half-wave potential (0.857 V vs. RHE) towards MOR and ORR, respectively. Thus, the RuMPt nanocomposite is a very promising material to be used as dual electrocatalyst in the application of PEMFCs.

  6. The tension of framed membranes from computer simulations

    Hamkens, Daniel; Jeppesen, Claus; Ipsen, John H.

    2018-01-01

    the membranes display power-law characteristics for the equation of state, while higher tension levels includes both an extended linear (elastic) as well as a highly non-linear stretching regime. For semi-flexible membranes a transition from extended to buckled conformations takes place at negative frame......Abstract.: We have analyzed the behavior of a randomly triangulated, self-avoiding surface model of a flexible, fluid membrane subject to a circular boundary by Wang-Landau Monte Carlo computer simulation techniques. The dependence of the canonical free energy and frame tension on the frame area...... is obtained for flexible membranes. It is shown that for low bending rigidities the framed membrane is only stable above a threshold tension, suggesting a discontinuous transition from the collapsed (branched polymer) state to a finite tension extended state. In a tension range above this threshold tension...

  7. Actin filaments as tension sensors.

    Galkin, Vitold E; Orlova, Albina; Egelman, Edward H

    2012-02-07

    The field of mechanobiology has witnessed an explosive growth over the past several years as interest has greatly increased in understanding how mechanical forces are transduced by cells and how cells migrate, adhere and generate traction. Actin, a highly abundant and anomalously conserved protein, plays a large role in forming the dynamic cytoskeleton that is so essential for cell form, motility and mechanosensitivity. While the actin filament (F-actin) has been viewed as dynamic in terms of polymerization and depolymerization, new results suggest that F-actin itself may function as a highly dynamic tension sensor. This property may help explain the unusual conservation of actin's sequence, as well as shed further light on actin's essential role in structures from sarcomeres to stress fibers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Flow Field Measurements of Methane-Oxygen Turbulent Nonpremixed Flames at High Pressure

    Iino, Kimio; Kikkawa, Hoshitaka; Akamatsu, Fumiteru; Katsuki, Masashi

    We carried out the flow field measurement of methane-oxygen turbulent nonpremixed flame in non-combusting and combusting situations at high pressures using LDV. The main objectives are to study the influences of combustion on the turbulence structure at high pressures and to provide detailed data on which numerical predictions on such flows can rely. Direct observation and CH* chemiluminescence detection are conducted at high pressures up to 1.0MPa. It was found that the flame length at elevated pressures became constant. From flow field measurements, the following features of flames at elevated pressure were found: (1) the existence of flame suppressed turbulence in the upstream region of the jet and enhanced it in the downstream region with increasing pressure; (2) Turbulence in the flame was more anisotropic than in the corresponding cold jet in all regions of the flow with increasing pressure; (3) Reynolds shear stresses did not change at elevated pressure; (4) Combustion processes had a marked influence on the turbulence macroscale under high pressures, however, the turbulence macroscale was not changed even with the increase in pressure.

  9. Unveiling the high-activity origin of single-atom iron catalysts for oxygen reduction reaction.

    Yang, Liu; Cheng, Daojian; Xu, Haoxiang; Zeng, Xiaofei; Wan, Xin; Shui, Jianglan; Xiang, Zhonghua; Cao, Dapeng

    2018-06-26

    It is still a grand challenge to develop a highly efficient nonprecious-metal electrocatalyst to replace the Pt-based catalysts for oxygen reduction reaction (ORR). Here, we propose a surfactant-assisted method to synthesize single-atom iron catalysts (SA-Fe/NG). The half-wave potential of SA-Fe/NG is only 30 mV less than 20% Pt/C in acidic medium, while it is 30 mV superior to 20% Pt/C in alkaline medium. Moreover, SA-Fe/NG shows extremely high stability with only 12 mV and 15 mV negative shifts after 5,000 cycles in acidic and alkaline media, respectively. Impressively, the SA-Fe/NG-based acidic proton exchange membrane fuel cell (PEMFC) exhibits a high power density of 823 mW cm -2 Combining experimental results and density-functional theory (DFT) calculations, we further reveal that the origin of high-ORR activity of SA-Fe/NG is from the Fe-pyrrolic-N species, because such molecular incorporation is the key, leading to the active site increase in an order of magnitude which successfully clarifies the bottleneck puzzle of why a small amount of iron in the SA-Fe catalysts can exhibit extremely superior ORR activity.

  10. Co- and defect-rich carbon nanofiber films as a highly efficient electrocatalyst for oxygen reduction

    Kim, Il To; Song, Myeong Jun; Shin, Seoyoon; Shin, Moo Whan

    2018-03-01

    Many efforts are continuously devoted to developing high-efficiency, low-cost, and highly scalable oxygen reduction reaction (ORR) electrocatalysts to replace precious metal catalysts. Herein, we successfully synthesize Co- and defect-rich carbon nanofibers (CNFs) using an efficient heat treatment approach involving the pyrolysis of electrospun fibers at 370 °C under air. The heat treatment process produces Co-decorated CNFs with a high Co mass ratio, enriched pyridinic N, Co-pyridinic Nx clusters, and defect-rich carbon structures. The synergistic effects from composition and structural changes in the designed material increase the number of catalytically active sites for the ORR in an alkaline solution. The prepared Co- and defect-rich CNFs exhibit excellent ORR activities with a high ORR onset potential (0.954 V vs. RHE), a large reduction current density (4.426 mA cm-2 at 0.40 V), and a nearly four-electron pathway. The catalyst also exhibits a better long-term durability than commercial Pt/C catalysts. This study provides a novel hybrid material as an efficient ORR catalyst and important insight into the design strategy for CNF-based hybrid materials as electrochemical electrodes.

  11. 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

  12. Improvement of Oxygenation in Severe Acute Respiratory Distress Syndrome With High-Volume Continuous Veno-venous Hemofiltration.

    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.

  13. Oxygen as a product of water radiolysis in high-LET tracks. II. Radiobiological implications

    Baverstock, K.F.; Burns, W.G.

    1981-01-01

    Consideration is given to the possibility that molecular oxygen generated in the tracks of energetic heavy ions is responsible for the reduction in oxygen enhancement ratio (OER) with increasing linear energy transfer (LET) observed for the loss of reproductive capacity caused by radiation in many cellular organisms. Yields of oxygen relationship of OER to LET for two organisms, Chlamydomonas reinhardii and Shigella flexneri, using a simple diffusion kinetic model for radiobiological action which takes account of the diffusion of oxygen after its formation. The results of these calculations show that the model accounts well for the shape of the OER vs. LET relationship

  14. Investigations on the kinetics of the oxygen reduction in high temperature fuel cells

    Erning, J.W.

    1998-07-01

    Lanthan-Strontium-Manganite perowskites are the most widespread materials in use for solid oxide fuel cell cathodes. The electrode reaction taking place, i.e. the reduction of oxygen supplied by air, was investigated by electrochemical means to obtain further knowledge about the electrode processes. The high activation energy of this reaction (200 kJ/mol), preventing lower operation temperatures of the SOFC, was the starting point for the investigation. Quasi steady state current voltage measurements and impedance spectroscopy were performed in a three electrode configuration. The electrodes were of circular shape with a diameter of 10 mm. The preparation was made by screen printing as well as wet powder spraying onto plates made of Yttria-stabilized zirconia. Perowskite powders of varying chemical and stoichiometric composition were used. To obtain higher power densities and, more important, lower apparent activation energies, catalytic layers were added at the interface electrode/electrolyte. Additionally, a less complex system, a model electrode/electrolyte setup made from single-crystal YSZ as electrolyte and gold in liquid and solid state as electrode was developed to create a better defined system. This setup was used to investigate the behaviour of the electrode/electrolyte interface. Reliable, reproducible results could be obtained using either setup. The experimental conditions i.e. oxygen partial pressure, temperature and overpotential were varied in order to determine the kinetic properties of the electrodes. Apparent activation energies, pre-exponential factors, apparent charge-transfer coefficients and electrochemical orders of reaction were calculated from the current-voltage data in order to propose possible reaction steps. (orig.)

  15. 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.

  16. Freestanding eggshell membrane-based electrodes for high-performance supercapacitors and oxygen evolution reaction

    Geng, Jing; Wu, Hao; Al-Enizi, Abdullah M.; Elzatahry, Ahmed A.; Zheng, Gengfeng

    2015-08-01

    A type of freestanding, light-weight eggshell membrane-based electrode is demonstrated for supercapacitors and for oxygen evolution reaction (OER) catalysis. As a widely available daily waste, eggshell membranes have unique porous three-dimensional grid-like fibrous structures with relatively high surface area and abundant macropores, allowing for effective conjugation of carbon nanotubes and growth of NiCo2O4 nanowire arrays, an effective supercapacitor material and OER catalyst. The three-dimensional fibrous eggshell membrane frameworks with carbon nanotubes offer efficient pathways for charge transport, and the macropores between adjacent fibers are fully accessible for electrolytes and bubble evolution. As a supercapacitor, the eggshell membrane/carbon nanotube/NiCo2O4 electrode shows high specific capacitances at current densities from 1 to 20 A g-1, with excellent capacitance retention (>90%) at 10 A g-1 for over 10 000 cycles. When employed as an OER catalyst, this eggshell membrane-based electrode exhibits an OER onset potential of 1.53 V vs. the reversible hydrogen electrode (RHE), and a stable catalytic current density of 20 mA cm-2 at 1.65 V vs. the RHE.A type of freestanding, light-weight eggshell membrane-based electrode is demonstrated for supercapacitors and for oxygen evolution reaction (OER) catalysis. As a widely available daily waste, eggshell membranes have unique porous three-dimensional grid-like fibrous structures with relatively high surface area and abundant macropores, allowing for effective conjugation of carbon nanotubes and growth of NiCo2O4 nanowire arrays, an effective supercapacitor material and OER catalyst. The three-dimensional fibrous eggshell membrane frameworks with carbon nanotubes offer efficient pathways for charge transport, and the macropores between adjacent fibers are fully accessible for electrolytes and bubble evolution. As a supercapacitor, the eggshell membrane/carbon nanotube/NiCo2O4 electrode shows high specific

  17. Singlet oxygen generation in a high pressure non-self-sustained electric discharge

    Hicks, Adam; Norberg, Seth; Shawcross, Paul; Lempert, Walter R; Rich, J William; Adamovich, Igor V

    2005-01-01

    This paper presents results of singlet oxygen generation experiments in a high-pressure, non-self-sustained crossed discharge. The discharge consists of a high-voltage, short pulse duration, high repetition rate pulsed discharge, which produces ionization in the flow, and a low-voltage dc discharge which sustains current in a decaying plasma between the pulses. The sustainer voltage can be independently varied to maximize the energy input into electron impact excitation of singlet delta oxygen (SDO). The results demonstrate operation of a stable and diffuse crossed discharge in O 2 -He mixtures at static pressures of at least up to P 0 = 380 Torr and sustainer discharge powers of at least up to 1200 W, achieved at P 0 = 120 Torr. The reduced electric field in the positive column of the sustainer discharge varies from E/N = 0.3 x 10 -16 to 0.65 X 10 -16 V cm 2 , which is significantly lower than E/N in self-sustained discharges and close to the theoretically predicted optimum value for O 2 (a 1 Δ) excitation. Measurements of visible emission spectra O 2 (b 1 Σ → X 3 Σ) in the discharge afterglow show the O 2 (b 1 Σ) concentration to increase with the sustainer discharge power and to decrease as the O 2 fraction in the flow is increased. Rotational temperatures inferred from these spectra in 10% O 2 -90% He flows at P 0 = 120 Torr and mass flow rates of m-dot = 2.2 are 365-465 K. SDO yield at these conditions, 1.7% to 4.4%, was inferred from the integrated intensity of the (0, 0) band of the O 2 (a 1 Δ → X 3 Σ) infrared emission spectra calibrated using a blackbody source. The yield remains nearly constant in the discharge afterglow, up to at least 15 cm distance from the discharge. Kinetic modelling calculations using a quasi-one-dimensional nonequilibrium pulser-sustainer discharge model coupled with the Boltzmann equation for plasma electrons predict gas temperature rise in the discharge in satisfactory agreement with the experimental measurements

  18. General definition of gravitational tension

    Harmark, T.; Obers, N.A.

    2004-01-01

    In this note we give a general definition of the gravitational tension in a given asymptotically translationally-invariant spatial direction of a space-time. The tension is defined via the extrinsic curvature in analogy with the Hawking-Horowitz definition of energy. We show the consistency with the ADM tension formulas for asymptotically-flat space-times, in particular for Kaluza-Klein black hole solutions. Moreover, we apply the general tension formula to near-extremal branes, constituting a check for non-asymptotically flat space-times. (author)

  19. Bilateral tension pneumothorax related to acupuncture.

    Tagami, Rumi; Moriya, Takashi; Kinoshita, Kosaku; Tanjoh, Katsuhisa

    2013-06-01

    We report on a patient with a rare case of bilateral tension pneumothorax that occurred after acupuncture. A 69-year-old large-bodied man, who otherwise had no risk factors for spontaneous pneumothorax, presented with chest pressure, cold sweats and shortness of breath. Immediately after bilateral pneumothorax had been identified on a chest radiograph in the emergency room, his blood pressure and percutaneous oxygen saturation suddenly decreased to 78 mm Hg and 86%, respectively. We confirmed deterioration in his cardiopulmonary status and diagnosed bilateral tension pneumothorax. We punctured his chest bilaterally and inserted chest tubes for drainage. His vital signs promptly recovered. After the bilateral puncture and drainage, we learnt that he had been treated with acupuncture on his upper back. We finally diagnosed a bilateral tension pneumothorax based on the symptoms that appeared 8 h after the acupuncture. Because the patient had no risk factors for spontaneous pneumothorax, no alternative diagnosis was proposed. We recommend that patients receiving acupuncture around the chest wall must be adequately informed of the possibility of complications and expected symptoms, as a definitive diagnosis can be difficult without complete information.

  20. Antioxidants keep the potentially probiotic but highly oxygen-sensitive human gut bacterium Faecalibacterium prausnitzii alive at ambient air

    Khan, M. Tanweer; van Dijl, Jan Maarten; Harmsen, Hermie J M

    2014-01-01

    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

  1. Real-Time, Non-Intrusive Detection of Liquid Nitrogen in Liquid Oxygen at High Pressure and High Flow

    Singh, Jagdish P.; Yueh, Fang-Yu; Kalluru, Rajamohan R.; Harrison, Louie

    2012-01-01

    An integrated fiber-optic Raman sensor has been designed for real-time, nonintrusive detection of liquid nitrogen in liquid oxygen (LOX) at high pressures and high flow rates in order to monitor the quality of LOX used during rocket engine ground testing. The integrated sensor employs a high-power (3-W) Melles Griot diode-pumped, solid-state (DPSS), frequency-doubled Nd:YAG 532- nm laser; a modified Raman probe that has built-in Raman signal filter optics; two high-resolution spectrometers; and photomultiplier tubes (PMTs) with selected bandpass filters to collect both N2 and O2 Raman signals. The PMT detection units are interfaced with National Instruments Lab- VIEW for fast data acquisition. Studies of sensor performance with different detection systems (i.e., spectrometer and PMT) were carried out. The concentration ratio of N2 and O2 can be inferred by comparing the intensities of the N2 and O2 Raman signals. The final system was fabricated to measure N2 and O2 gas mixtures as well as mixtures of liquid N2 and LOX

  2. The Largs high-latitude oxygen isotope anomaly (New Zealand) and climatic controls of oxygen isotopes in magma

    Blattner, P.; Williams, J.G.

    1991-01-01

    In northern Fiordland the Brook Street terrane of New Zealand consists of two units - the predominantly basaltic Plato and the predominantly andesitic Largs terrane. The Permian Plato terrane has normal to slightly enriched δ 18 O values, whereas the Largs terrane, which is of similar pre-early Triassic age, has not yielded a single normal δ 18 O SMOW result, with all of 17 total rocks showing less than 3.2per mille, seven less than -4per mille, and two less than -9per mille. These strongly anomalous data confirm an earlier suggested terrestrial character of Largs deposition, and demand the presence of Permo-Triassic geothermal systems running on subAntarctic to Antarctic meteoric water. The skewed data spectrum suggests a relatively immature flow system and likely values for the recharge water are -20per mille δ 18 O or less. For a climate distribution similar to the present one, inlcuding polar ice caps, this would indicate over 70deg of southern latitude. Rafts and xenoliths of Largs rocks have been entrained within Mackay Intrusives in the early Triassic. On field evidence the Mackay magmas have also intruded an early Darran Complex, but this complex has been substantially reactivated in the Cretaceous. It has δ 18 O values near 5.0per mille, which is distinctly low for island arc magmas. Since the complex is isotopically homogenous, its δ 18 O is unlikely to be a direct effect of the relatively shallow Largs terrane. More probable is a climate related slight depression of the δ 18 O of magma sources, in which other high-latitude, low-δ 18 O sediments and geothermal systems have been involved. (orig.)

  3. Balance of oxygen throughout the conversion of a high-level waste melter feed to glass

    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

  4. Solubility of corrosion products of plain steel in oxygen-containing water solutions at high parameters

    Martynova, O.I.; Samojlov, Yu.F.; Petrova, T.I.; Kharitonova, N.L.

    1983-01-01

    Technique for calculation of solubility of iron corrosion products in oxygen-containing aqueous solutions in the 298-573 K temperature range is presented. Solubility of corrosion products of plain steel in deeply-desalinizated water in the presence of oxygen for the such range of the temperatures is experimentally determined. Rather good convergence between calculated and experimental data is noted

  5. Oxygen adsorption on Pt(110)-(1x2): new high-coverage structures

    Helveg, Stig; Lorensen, Henrik Qvist; Horch, Sebastian

    1999-01-01

    From an interplay between scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations, a comprehensive picture is obtained for oxygen adsorption on the Pt(110)-(1 x 2) surface, from single isolated oxygen atoms chemisorbed in FCC sites along the platinum ridges...... adsorption and platinum lattice distortions. (C) 1999 Elsevier Science B.V. All rights reserved....

  6. Oxygen reduction on carbon supported platinum catalysts in high temperature polymer electrolytes

    Qingfeng, Li; Bergqvist, R. S.; Hjuler, H. A.

    1999-01-01

    Oxygen reduction on carbon supported platinum catalysts has been investigated in H3PO4, H3PO4-doped Nafion and PBI polymer electrolytes in a temperature range from 80 to 190°C. Compared with pure H3PO4, using the H3PO4 doped Nafion and PBI polymer electrolytes can significantly improve the oxygen...

  7. Secular distribution of highly metalliferous black shales corresponds with peaks in past atmosphere oxygenation

    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

  8. Characteristics of high altitude oxygen ion energization and outflow as observed by Cluster: a statistical study

    Nilsson, H.; Waara, M.; Arvelius, S.; Yamauchi, M.; Lundin, R. [Inst. of Space Physics, Kiruna (Sweden); Marghitu, O. [Max-Planck-Inst. fuer Extraterrestriche Physik, Garching (Germany); Inst. for Space Sciences, Bucharest (Romania); Bouhram, M. [Max-Planck-Inst. fuer Extraterrestriche Physik, Garching (Germany); CETP-CNRS, Saint-Maur (France); Hobara, Y. [Inst. of Space Physics, Kiruna (Sweden); Univ. of Sheffield, Sheffield (United Kingdom); Reme, H.; Sauvaud, J.A.; Dandouras, I. [Centre d' Etude Spatiale des Rayonnements, Toulouse (France); Balogh, A. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom); Kistler, L.M. [Univ. of New Hampshire, Durham (United States); Klecker, B. [Max-Planck-Inst. fuer Extraterrestriche Physik, Garching (Germany); Carlson, C.W. [Space Science Lab., Univ. of California, Berkeley (United States); Bavassano-Cattaneo, M.B. [Ist. di Fisica dello Spazio Interplanetario, Roma (Italy); Korth, A. [Max-Planck-Inst. fuer Sonnensystemforschung, Katlenburg-Lindau (Germany)

    2006-07-01

    The results of a statistical study of oxygen ion outflow using cluster data obtained at high altitude above the polar cap is reported. Moment data for both hydrogen ions (H{sup +}) and oxygen ions (O{sup +}) from 3 years (2001-2003) of spring orbits (January to May) have been used. The altitudes covered were mainly in the range 5-12 R{sub E} geocentric distance. It was found that O{sup +} is significantly transversely energized at high altitudes, indicated both by high perpendicular temperatures for low magnetic field values as well as by a tendency towards higher perpendicular than parallel temperature distributions for the highest observed temperatures. The O{sup +} parallel bulk velocity increases with altitude in particular for the lowest observed altitude intervals. O{sup +} parallel bulk velocities in excess of 60 km s{sup -1} were found mainly at higher altitudes corresponding to magnetic field strengths of less than 100 nT. For the highest observed parallel bulk velocities of O{sup +} the thermal velocity exceeds the bulk velocity, indicating that the beam-like character of the distribution is lost. The parallel bulk velocity of the H{sup +} and O{sup +} was found to typically be close to the same throughout the observation interval when the H{sup +} bulk velocity was calculated for all pitch-angles. When the H{sup +} bulk velocity was calculated for upward moving particles only the H{sup +} parallel bulk velocity was typically higher than that of O{sup +}. The parallel bulk velocity is close to the same for a wide range of relative abundance of the two ion species, including when the O{sup +} ions dominates. The thermal velocity of O{sup +} was always well below that of H{sup +}. Thus perpendicular energization that is more effective for O{sup +} takes place, but this is not enough to explain the close to similar parallel velocities. Further parallel acceleration must occur. The results presented constrain the models of perpendicular heating and parallel

  9. Characteristics of high altitude oxygen ion energization and outflow as observed by Cluster: a statistical study

    H. Nilsson

    2006-05-01

    Full Text Available The results of a statistical study of oxygen ion outflow using Cluster data obtained at high altitude above the polar cap is reported. Moment data for both hydrogen ions (H+ and oxygen ions (O+ from 3 years (2001-2003 of spring orbits (January to May have been used. The altitudes covered were mainly in the range 5–12 RE geocentric distance. It was found that O+ is significantly transversely energized at high altitudes, indicated both by high perpendicular temperatures for low magnetic field values as well as by a tendency towards higher perpendicular than parallel temperature distributions for the highest observed temperatures. The O+ parallel bulk velocity increases with altitude in particular for the lowest observed altitude intervals. O+ parallel bulk velocities in excess of 60 km s-1 were found mainly at higher altitudes corresponding to magnetic field strengths of less than 100 nT. For the highest observed parallel bulk velocities of O+ the thermal velocity exceeds the bulk velocity, indicating that the beam-like character of the distribution is lost. The parallel bulk velocity of the H+ and O+ was found to typically be close to the same throughout the observation interval when the H+ bulk velocity was calculated for all pitch-angles. When the H+ bulk velocity was calculated for upward moving particles only the H+ parallel bulk velocity was typically higher than that of O+. The parallel bulk velocity is close to the same for a wide range of relative abundance of the two ion species, including when the O+ ions dominates. The thermal velocity of O+ was always well below that of H+. Thus perpendicular energization that is more effective for O+ takes place, but this is not enough to explain the close to similar parallel velocities. Further

  10. Characteristics of high altitude oxygen ion energization and outflow as observed by Cluster: a statistical study

    H. Nilsson

    2006-05-01

    Full Text Available The results of a statistical study of oxygen ion outflow using Cluster data obtained at high altitude above the polar cap is reported. Moment data for both hydrogen ions (H+ and oxygen ions (O+ from 3 years (2001-2003 of spring orbits (January to May have been used. The altitudes covered were mainly in the range 5–12 RE geocentric distance. It was found that O+ is significantly transversely energized at high altitudes, indicated both by high perpendicular temperatures for low magnetic field values as well as by a tendency towards higher perpendicular than parallel temperature distributions for the highest observed temperatures. The O+ parallel bulk velocity increases with altitude in particular for the lowest observed altitude intervals. O+ parallel bulk velocities in excess of 60 km s-1 were found mainly at higher altitudes corresponding to magnetic field strengths of less than 100 nT. For the highest observed parallel bulk velocities of O+ the thermal velocity exceeds the bulk velocity, indicating that the beam-like character of the distribution is lost. The parallel bulk velocity of the H+ and O+ was found to typically be close to the same throughout the observation interval when the H+ bulk velocity was calculated for all pitch-angles. When the H+ bulk velocity was calculated for upward moving particles only the H+ parallel bulk velocity was typically higher than that of O+. The parallel bulk velocity is close to the same for a wide range of relative abundance of the two ion species, including when the O+ ions dominates. The thermal velocity of O+ was always well below that of H+. Thus perpendicular energization that is more effective for O+ takes place, but this is not enough to explain the close to similar parallel velocities. Further parallel acceleration must occur. The results presented constrain the models of perpendicular heating and parallel acceleration. In particular centrifugal acceleration of the outflowing ions, which may

  11. A new high accuracy non-polynomial tension spline method for the solution of one dimensional wave equation in polar co-ordinates

    Venu Gopal

    2014-07-01

    Full Text Available In this paper, we propose a new three-level implicit nine point compact finite difference formulation of O(k2 + h4 based on non-polynomial tension spline approximation in r-direction and finite difference approximation in t-direction for the numerical solution of one dimensional wave equation in polar co-ordinates. We describe the mathematical formulation procedure in details and also discuss the stability of the method. Numerical results are provided to justify the usefulness of the proposed method.

  12. Oxygen doping of the high T/sub c/ superconducting perovskites

    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

  13. Change in the work function of zirconium by oxidation at high temperatures and low oxygen pressures

    Maeno, Yutaka; Yamamoto, Masahiro; Naito, Shizuo; Mabuchi, Mahito; Hashino, Tomoyasu

    1991-01-01

    Changes in the work function of zirconium on oxidation are measured at oxygen pressures of 3.0 x 10 -6 - 3.0 x 10 -4 Pa and at temperatures in the range 426-775 K. The work function first decreases then increases until a final saturation stage is reached. Use of secondary-ion mass spectroscopy (SIMS) shows that the changes correspond to oxygen adsorption, oxide nucleation and oxide growth, respectively. The initial decrease in work function is interpreted by the incorporation of oxygen adatoms into the subsurface. The oxygen adsorption potential of zirconium is evaluated by an effective medium theory, and the physical origin of the incorporation of oxygen adatoms is discussed. The positive change in the work function caused by oxide formation and the temperature and pressure dependences of the change in the work function by oxidation are explained qualitatively. (author)

  14. High Temperature Oxidation of Steel in an Oxygen-enriched Low NOX Furnace Environment

    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.

  15. The law of corresponding states and surface tension of metals

    Digilov, R.

    2001-01-01

    Full Text: Surface tension of liquid metals is one of fundamental and most important quantities in theory and practice of material processing and its temperature dependence leads to the well-known Marangoni convection. Although currently methods are sufficiently precise to measure the surface tension, there are uncertainties in experimental data and its temperature dependence mainly due to impurity, which even a trace of it strongly affects the results of measurements. The theoretical treatment from the first principles is unwieldy and not always permits one to calculate the surface tension with certainty. Another active research field deals with empirical correlation between the surface tension and bulk thermodynamic properties, which we interpret as a simple consequence of the law of corresponding states. In order to relate the surface tension and to bulk properties of liquid metals the reduced formula is derived by scaling with the melting point T m (0) at p = 0 and atomic volume Ω 0 2/3 at T = 0 K as macroscopic parameters for scaling ε and a characterizing the interatomic potential in metals. The reduced surface tension and the reduced surface entropy obtained in high temperature limit are discussed and compared with the experiment. The reduced temperature coefficient of the surface tension found is a universal constant for the metals of the same structure. It is shown that pressure dependence of the surface tension, so called baric coefficient of the surface tension, can be described by pressure dependence of scaling parameters T m (p) and Ω 0 (p). (author)

  16. Freestanding eggshell membrane-based electrodes for high-performance supercapacitors and oxygen evolution reaction.

    Geng, Jing; Wu, Hao; Al-Enizi, Abdullah M; Elzatahry, Ahmed A; Zheng, Gengfeng

    2015-09-14

    A type of freestanding, light-weight eggshell membrane-based electrode is demonstrated for supercapacitors and for oxygen evolution reaction (OER) catalysis. As a widely available daily waste, eggshell membranes have unique porous three-dimensional grid-like fibrous structures with relatively high surface area and abundant macropores, allowing for effective conjugation of carbon nanotubes and growth of NiCo2O4 nanowire arrays, an effective supercapacitor material and OER catalyst. The three-dimensional fibrous eggshell membrane frameworks with carbon nanotubes offer efficient pathways for charge transport, and the macropores between adjacent fibers are fully accessible for electrolytes and bubble evolution. As a supercapacitor, the eggshell membrane/carbon nanotube/NiCo2O4 electrode shows high specific capacitances at current densities from 1 to 20 A g(-1), with excellent capacitance retention (>90%) at 10 A g(-1) for over 10,000 cycles. When employed as an OER catalyst, this eggshell membrane-based electrode exhibits an OER onset potential of 1.53 V vs. the reversible hydrogen electrode (RHE), and a stable catalytic current density of 20 mA cm(-2) at 1.65 V vs. the RHE.

  17. High-Performance Pyrochlore-Type Yttrium Ruthenate Electrocatalyst for Oxygen Evolution Reaction in Acidic Media

    Kim, Jaemin [Department; Shih, Pei-Chieh [Department; Tsao, Kai-Chieh [Department; Pan, Yung-Tin [Department; Yin, Xi [Department; Sun, Cheng-Jun [X-ray; Yang, Hong [Department

    2017-08-17

    Development of acid-stable electrocatalysts with low overpotential for oxygen evolution reaction (OER) is a major challenge for the production of hydrogen directly from water. We report in this paper a pyrochlore yttrium ruthenate (Y2Ru2O7-δ) electrocatalyst that has significantly enhanced performance towards OER in acid media over the best-known catalysts, with an onset overpotential of 190 mV and high stability in 0.1-M perchloric acid solution. X-ray absorption near-edge structure (XANES) indicates Y2Ru2O7-δ electrocatalyst had a low valence state that favors the high OER activity. Density functional theory (DFT) calculation shows this pyrochlore has lower band center energy for the overlap between Ru 4d and O 2p orbitals and therefore more stable Ru-O bond than RuO2, highlighting the effect of yttrium on the enhancement in stability. The Y2Ru2O7-δ pyrochlore is also free of expensive iridium metal, thus a cost-effective candidate for practical applications.

  18. High Oxygen Reduction Reaction Performances of Cathode Materials Combining Polyoxometalates, Coordination Complexes, and Carboneous Supports.

    Zhang, Shuangshuang; Oms, Olivier; Hao, Long; Liu, Rongji; Wang, Meng; Zhang, Yaqin; He, Hong-Yan; Dolbecq, Anne; Marrot, Jérôme; Keita, Bineta; Zhi, Linjie; Mialane, Pierre; Li, Bin; Zhang, Guangjin

    2017-11-08

    A series of carbonaceous-supported precious-metal-free polyoxometalate (POM)-based composites which can be easily synthesized on a large scale was shown to act as efficient cathode materials for the oxygen reduction reaction (ORR) in neutral or basic media via a four-electron mechanism with high durability. Moreover, exploiting the versatility of the considered system, its activity was optimized by the judicious choice of the 3d metals incorporated in the {(PW 9 ) 2 M 7 } (M = Co, Ni) POM core, the POM counterions and the support (thermalized triazine-based frameworks (TTFs), fluorine-doped TTF (TTF-F), reduced graphene oxide, or carbon Vulcan XC-72. In particular, for {(PW 9 ) 2 Ni 7 }/{Cu(ethylenediamine) 2 }/TTF-F, the overpotential required to drive the ORR compared well with those of Pt/C. This outstanding ORR electrocatalytic activity is linked with two synergistic effects due to the binary combination of the Cu and Ni centers and the strong interaction between the POM molecules and the porous and highly conducting TTF-F framework. To our knowledge, {(PW 9 ) 2 Ni 7 }/{Cu(ethylenediamine) 2 }/TTF-F represents the first example of POM-based noble-metal-free ORR electrocatalyst possessing both comparable ORR electrocatalytic activity and much higher stability than that of Pt/C in neutral medium.

  19. Reducing pulmonary injury by hyperbaric oxygen preconditioning during simulated high altitude exposure in rats.

    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.

  20. High time resolution measurements of the thermosphere from Fabry-Perot Interferometer measurements of atomic oxygen

    E. A. K. Ford

    2007-06-01

    Full Text Available Recent advances in the performance of CCD detectors have enabled a high time resolution study of the high latitude upper thermosphere with Fabry-Perot Interferometers (FPIs to be performed. 10-s integration times were used during a campaign in April 2004 on an FPI located in northern Sweden in the auroral oval. The FPI is used to study the thermosphere by measuring the oxygen red line emission at 630.0 nm, which emits at an altitude of approximately 240 km. Previous time resolutions have been 4 min at best, due to the cycle of look directions normally observed. By using 10 s rather than 40 s integration times, and by limiting the number of full cycles in a night, high resolution measurements down to 15 s were achievable. This has allowed the maximum variability of the thermospheric winds and temperatures, and 630.0 nm emission intensities, at approximately 240 km, to be determined as a few minutes. This is a significantly greater variability than the often assumed value of 1 h or more. A Lomb-Scargle analysis of this data has shown evidence of gravity wave activity with waves with short periods. Gravity waves are an important feature of mesosphere-lower thermosphere (MLT dynamics, observed using many techniques and providing an important mechanism for energy transfer between atmospheric regions. At high latitudes gravity waves may be generated in-situ by localised auroral activity. Short period waves were detected in all four clear nights when this experiment was performed, in 630.0 nm intensities and thermospheric winds and temperatures. Waves with many periodicities were observed, from periods of several hours, down to 14 min. These waves were seen in all parameters over several nights, implying that this variability is a typical property of the thermosphere.

  1. Tension type headaches: a review

    Location of the pain:There is often a typical location for tension- type headaches, as ... Cranial nerve abnormalities, including papilloedema. • Signs of ... peripheral and central mechanisms underlie tension-type ... Physiotherapy has been shown to be an effective management option for .... Acupuncture in primary headache.

  2. Inadequate cerebral oxygen delivery and central fatigue during strenuous exercise

    Nybo, Lars; Rasmussen, Peter

    2007-01-01

    Under resting conditions, the brain is protected against hypoxia because cerebral blood flow increases when the arterial oxygen tension becomes low. However, during strenuous exercise, hyperventilation lowers the arterial carbon dioxide tension and blunts the increase in cerebral blood flow, which...... can lead to an inadequate oxygen delivery to the brain and contribute to the development of fatigue....

  3. La2CuO4+δ: Synthesis under high oxygen pressure and study of phase relations and energetics

    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 )

  4. 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).

  5. Locomotor muscle fatigue does not alter oxygen uptake kinetics during high-intensity exercise

    James Hopker

    2016-10-01

    Full Text Available The slow component (VO2sc that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre fatigue condition or rest for 33 minutes (control condition according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-second maximal sprints at a fixed pedaling cadence of 90 rev·min-1. Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and VO2max determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue (P = 0.03, the VO2sc was not significantly different between the pre fatigue (464 ± 301 mL·min-1 and the control (556 ± 223 mL·min-1 condition (P = 0.50. Blood lactate response was not significantly different between conditions (P = 0.48 but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition (P < 0.01 suggesting higher muscle recruitment. These results demonstrate experimentally that locomotor muscle fatigue does not significantly alter the VO2 kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the VO2sc is strongly associated with locomotor muscle fatigue.

  6. Locomotor Muscle Fatigue Does Not Alter Oxygen Uptake Kinetics during High-Intensity Exercise.

    Hopker, James G; Caporaso, Giuseppe; Azzalin, Andrea; Carpenter, Roger; Marcora, Samuele M

    2016-01-01

    The [Formula: see text] slow component ([Formula: see text]) that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre-fatigue condition) or rest for 33 min (control condition) according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-s maximal sprints at a fixed pedaling cadence of 90 rev·min -1 . Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE) were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and [Formula: see text] determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue ( P = 0.03), the [Formula: see text] was not significantly different between the pre-fatigue (464 ± 301 mL·min -1 ) and the control (556 ± 223 mL·min -1 ) condition ( P = 0.50). Blood lactate response was not significantly different between conditions ( P = 0.48) but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition ( P locomotor muscle fatigue does not significantly alter the [Formula: see text] kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the [Formula: see text] is strongly associated with locomotor muscle fatigue.

  7. Nitrogen-doped graphene-wrapped iron nanofragments for high-performance oxygen reduction electrocatalysts

    Lee, Jang Yeol [Korea Institute of Science and Technology, Photo-Electronic Hybrid Research Center (Korea, Republic of); Kim, Na Young [Korea Institute of Science and Technology, Fuel Cell Research Center (Korea, Republic of); Shin, Dong Yun [Chungbuk National University, Department of Environmental Engineering (Korea, Republic of); Park, Hee-Young [Korea Institute of Science and Technology, Fuel Cell Research Center (Korea, Republic of); Lee, Sang-Soo [Korea Institute of Science and Technology, Photo-Electronic Hybrid Research Center (Korea, Republic of); Joon Kwon, S. [Korea Institute of Science and Technology, Nanophotonics Research Center (Korea, Republic of); Lim, Dong-Hee [Chungbuk National University, Department of Environmental Engineering (Korea, Republic of); Bong, Ki Wan [Korea University, Department of Chemical and Biological Engineering (Korea, Republic of); Son, Jeong Gon, E-mail: jgson@kist.re.kr [Korea Institute of Science and Technology, Photo-Electronic Hybrid Research Center (Korea, Republic of); Kim, Jin Young, E-mail: jinykim@kist.re.kr [Korea Institute of Science and Technology, Fuel Cell Research Center (Korea, Republic of)

    2017-03-15

    Transition metals, such as iron (Fe)- or cobalt (Co)-based nanomaterials, are promising electrocatalysts for oxygen reduction reactions (ORR) in fuel cells due to their high theoretical activity and low cost. However, a major challenge to using these metals in place of precious metal catalysts for ORR is their low efficiency and poor stability, thus new concepts and strategies should be needed to address this issue. Here, we report a hybrid aciniform nanostructures of Fe nanofragments embedded in thin nitrogen (N)-doped graphene (Fe@N-G) layers via a heat treatment of graphene oxide-wrapped iron oxide (Fe{sub 2}O{sub 3}) microparticles with melamine. The heat treatment leads to transformation of Fe{sub 2}O{sub 3} microparticles to nanosized zero-valent Fe fragments and formation of core-shell structures of Fe nanofragments and N-doped graphene layers. Thin N-doped graphene layers massively promote electron transfer from the encapsulated metals to the graphene surface, which efficiently optimizes the electronic structure of the graphene surface and thereby triggers ORR activity at the graphene surface. With the synergistic effect arising from the N-doped graphene and Fe nanoparticles with porous aciniform nanostructures, the Fe@N-G hybrid catalyst exhibits high catalytic activity, which was evidenced by high E{sub 1/2} of 0.82 V, onset potential of 0.93 V, and limiting current density of 4.8 mA cm{sup −2} indicating 4-electron ORR, and even exceeds the catalytic stability of the commercial Pt catalyst.

  8. Lanthanides-based graphene catalysts for high performance hydrogen evolution and oxygen reduction

    Shinde, S.S.; Sami, Abdul; Lee, Jung-Ho

    2016-01-01

    Highlights: • Facile, scalable in-situ synthesis of lanthanide (La, Eu, Yb) doped graphene frameworks. • Efficient electrocatalytic performance towards HER and ORR. • Eu-Gr hybrid shows HER performance; onset & overpotential (81 & 160 mV), & Tafel slope (52 mV dec −1 ). • Eu-Gr exhibits superior activity of ORR; onset potential (0.92 V), electron transfer number (4.03). • Excellent long-term stability in HER and ORR, comparable to those of commercial Pt/C catalysts. - Abstract: The design of efficient electrocatalysts for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) has received enormous consideration due to their effectiveness in modern renewable energy technologies such as fuel cells, electrolyzers, and metal–air batteries. Herein, we present a facile method to fabricate lanthanides (L = La, Eu, Yb)-doped graphene materials as catalyst for the HER and ORR that show desirable electrocatalytic activities as well as long-term stability. The Eu-graphene hybrid has showed unbeatable HER performance such as small values of onset potential (81 mV), overpotential (160 mV), and Tafel slope (52 mV dec −1 ), along with a high exchange current density (7.55 × 10 −6 A cm −2 ). The L-graphenes also exhibit superior electrocatalytic activity for ORR, including small Tafel slopes (96, 66, and 105 mV dec −1 for La-Gr, Eu-Gr, and Yb-Gr, respectively), positive onset potential (∼0.83–0.92 V), high electron transfer numbers (∼3.84–4.03), and excellent enduring strength, analogous to those of viable Pt/C catalysts. The excellent electrocatalytic performance is attributed to the synergistic effect of abundant edges and doping sites, high electrical conductivity, large active surface areas and fast charge transfer; which renders lanthanide-based graphene hybrids as potentially great candidate for energy conversion systems.

  9. Ultrafine and highly disordered Ni 2 Fe 1 nanofoams enabled highly efficient oxygen evolution reaction in alkaline electrolyte

    Fu, Shaofang; Song, Junhua; Zhu, Chengzhou; Xu, Gui-Liang; Amine, Khalil; Sun, Chengjun; Li, Xiaolin; Engelhard, Mark H.; Du, Dan; Lin, Yuehe

    2018-02-01

    Nickel iron hydroxides are the most promising non-noble electrocatalysts for oxygen evolution reaction (OER) in alkaline media. By in situ reduction of metal precursors, compositionally controlled three-dimensional (3D) NixFeyB nanofoams (NFs) are synthesized with high surface area and uniformly distributed bimetallic networks. The resultant ultrafine amorphous Ni2Fe1B NFs exhibit extraordinary electrocatalytic performance toward OER and overall water splitting in alkaline media. At a potential as low as 1.42 V (vs. RHE), Ni2Fe1B NFs can deliver a current density of 10 mA/cm2 and show negligible activity loss after 12 hours’ stability test. Even at large current flux of 100 mA/cm2, an ultralow overpotential of 0.27 V is achieved, which is about 0.18 V more negative than benchmark RuO2. Both ex-situ Mӧssbauer spectroscopy and X-ray Absorption Spectroscopy (XAS) reveal a phase separation and transformation for the Ni2Fe1B catalyst during OER process. The evolution of oxidation state and disordered structure of Ni2Fe1B might be a key to the high catalytic performance for OER.

  10. Selection for high and low oxygen consumption-induced differences in maintenance energy requirements of mice.

    Darhan, Hongyu; Kikusato, Motoi; Toyomizu, Masaaki; Roh, Sang-Gun; Katoh, Kazuo; Sato, Masahiro; Suzuki, Keiichi

    2017-07-01

    Maintenance energy requirements (MER) of mice selected for high (H) or low (L) oxygen consumption (OC) were compared. Forty-four mice from H and L OC lines were weaned at 3 weeks and divided into four experimental groups: group A were sacrificed at 4 weeks; group B were fed ad libitum, and groups C and D were fed 2.8 and 2.4 g/day, respectively, from 4 to 8 weeks of age. Groups B-D were sacrificed at 8 weeks. Chemical components were estimated for all groups. MER was estimated using a model that partitioned metabolizable energy intake into that used for maintenance, and protein and fat deposition. The feed conversion ratio for the B group was significantly higher in the H than in the L line. Feed intake for metabolic energy content per metabolic body size was significantly also higher in the H line, whereas accumulated energy content per metabolic body size was significantly higher in the L line. MER of the H line was greater than that of the L line (P < 0.10). These results suggest that selection for H or L OC produced differences in chemical components, feed efficiency, and MER between the H and L lines. © 2016 Japanese Society of Animal Science.

  11. EdF: high tension(s) metamorphosis

    Roussely, F.; Arnoux, P.; Baritault, A.; Alto, P.; Castets, C.; Secondi, J.

    2003-01-01

    Electricite de France, the French electric utility, has to face a formidable mutation. The deregulation of the power market will lead to a social, commercial, judicial, financial and international 'big-bang'. The company has been weakened by disappointing results and by an embarrassing running into debts. This dossier analyzes the consequences of the deregulation of the French power market on the future evolution of EdF. It includes the analysis made by a French economist, E. Cohen, an interview and a portrait of F. Roussely, head of EdF, a presentation of Easenergy, a start-up of EdF which makes partnerships with US energy-related companies, the worries of EdF's employees and the redistribution of the syndicates power inside the company, the controversy around EdF's 2002 results and the points that remained in the shade, EdF's European competitors and the progressive opening of the French power market, EDF's production tool and its availability (58 nuclear reactors, 538 hydroelectric power plants and 26 thermal power plants), the costly foreign markets strategy of EdF and the under-capitalization of the company. (J.S.)

  12. Oxygen isotope systematics of chondrules in the Allende CV3 chondrite: High precision ion microprobe studies

    Rudraswami, N.G.; Ushikubo, T.; Nakashima, D.; Kita, N.T.

    grains and some of them were derived from precursors related to refractory inclusions. However, most relict olivine grains show oxygen isotope ratios that overlap with those in homogeneous chondrules. The delta sup(17)O values of four barred olivine...

  13. Optimization of Glucose oxidase towards oxygen independency and high mediator activity for amperometric glucose determination in diabetes analytics

    Arango Gutierrez, Erik Uwe

    2015-01-01

    Glucose oxidase is an oxidoreductase exhibiting a high β-D-glucose specificity and high stability which renders glucose oxidase well-suited for applications in diabetes care. Nevertheless, GOx activity is highly oxygen dependent which can lead to inaccuracies in amperometric β-D-glucose determinations. Therefore a directed evolution campaign with two rounds of random mutagenesis (SeSaM followed by epPCR), site saturation mutagenesis studies, and one simultaneous site saturation library (OmniC...

  14. Effect of oxygen at low and high light intensities on the growth of Neochloris oleoabundans

    Sousa, C.A.; Compadre, A.; Vermuë, M.H.; Wijffels, R.H.

    2013-01-01

    The effect of partial oxygen pressure on growth of Neochloris oleoabundans was studied at near-saturating light intensity in a fully-controlled photobioreactor. At the partial oxygen pressures tested (PO2=0.24; 0.42; 0.63; 0.84 bar), the specific growth rate was 1.36; 1.16; 0.93 and 0.68 day-1,

  15. Perceptions of hyperbaric oxygen therapy among podiatrists practicing in high-risk foot clinics.

    Henshaw, Frances R; Brennan, Lauren; MacMillan, Freya

    2018-01-03

    Foot ulceration is a devastating and costly consequence of diabetes. Hyperbaric oxygen therapy is recognised as an adjunctive therapy to treat diabetes-related foot ulceration, yet uptake is low. Semi-structured interviews were conducted with 16 podiatrists who manage patients with foot ulcers related to diabetes to explore their perceptions of, and the barriers/facilitators to, referral for hyperbaric oxygen. Podiatrists cited logistical issues such as location of facilities as well as poor communication pathways, lack of delegation and lack of follow up when patients presented for hyperbaric treatment. In general, podiatrists had an understanding of the premise of hyperbaric oxygen therapy and evidence to support its use but could only provide very limited citations of key papers and guidelines to support their position. Podiatrists stated that they felt a patient was lost from their care when referred for hyperbaric oxygen and that aftercare might not be adequate. Improved referral and delegation pathways for patients presenting for hyperbaric oxygen, as well as the provision of easily accessible evidence to support this therapy, could help to increase podiatrists' confidence in deciding whether or not to recommend their patients for hyperbaric oxygen therapy. © 2018 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

  16. Oxygen reduction reaction on a highly-alloyed Pt-Ni supported carbon electrocatalyst in acid solution

    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...

  17. High-frequency climate linkages between the North Atlantic and the Mediterranean during marine oxygen isotope stage 100 (MIS100)

    Becker, Julia; Lourens, L.J.; Raymo, M.E.

    2006-01-01

    High-resolution records of Mediterranean and North Atlantic deep-sea sediments indicate that rapid changes in hydrology and climate occurred during marine oxygen isotope stage 100 (MIS100) (at ~2.52 Ma), which exhibits characteristics similar to late Pleistocene Dansgaard-Oeschger, Bond cycles and

  18. 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.

  19. Synergistic effects of liquid and gas phase discharges using pulsed high voltage for dyes degradation in the presence of oxygen.

    Yang, Bin; Zhou, Minghua; Lei, Lecheng

    2005-07-01

    The technology of combined liquid and gas phase discharges (LGD) using pulsed high voltage for dyes degradation was developed in this study. Apparent synergistic effects for Acid orange II (AO) degradation in the presence of oxygen were observed. The enhancement of AO degradation rate was around 302%. Furthermore, higher energy efficiency was obtained comparing with individual liquid phase discharge (LD) or gas phase discharge process (GD). The AO degradation in the presence of oxygen by LGD proceeded through the direct ozone oxidation and the ozone decomposition induced by LD. Important operating parameters such as electrode distance, applied voltage, pulse repetition rate, and types of dyes were further investigated.

  20. Membrane tension regulates clathrin-coated pit dynamics

    Liu, Allen

    2014-03-01

    Intracellular organization depends on close communication between the extracellular environment and a network of cytoskeleton filaments. The interactions between cytoskeletal filaments and the plasma membrane lead to changes in membrane tension that in turns help regulate biological processes. Endocytosis is thought to be stimulated by low membrane tension and the removal of membrane increases membrane tension. While it is appreciated that the opposing effects of exocytosis and endocytosis have on keeping plasma membrane tension to a set point, it is not clear how membrane tension affects the dynamics of clathrin-coated pits (CCPs), the individual functional units of clathrin-mediated endocytosis. Furthermore, although it was recently shown that actin dynamics counteracts membrane tension during CCP formation, it is not clear what roles plasma membrane tension plays during CCP initiation. Based on the notion that plasma membrane tension is increased when the membrane area increases during cell spreading, we designed micro-patterned surfaces of different sizes to control the cell spreading sizes. Total internal reflection fluorescence microscopy of living cells and high content image analysis were used to quantify the dynamics of CCPs. We found that there is an increased proportion of CCPs with short (<20s) lifetime for cells on larger patterns. Interestingly, cells on larger patterns have higher CCP initiation density, an effect unexpected based on the conventional view of decreasing endocytosis with increasing membrane tension. Furthermore, by analyzing the intensity profiles of CCPs that were longer-lived, we found CCP intensity decreases with increasing cell size, indicating that the CCPs are smaller with increasing membrane tension. Finally, disruption of actin dynamics significantly increased the number of short-lived CCPs, but also decreased CCP initiation rate. Together, our study reveals new mechanistic insights into how plasma membrane tension regulates

  1. Organic hydrogen peroxide-driven low charge potentials for high-performance lithium-oxygen batteries with carbon cathodes

    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.

  2. Studies on the oxygen precipitation in highly boron doped silicon; Untersuchungen zur Sauerstoffausscheidung in hoch bordotiertem Silicium

    Zschorsch, Markus

    2007-12-14

    The aim of this thesis was the getting of new knowledge on the elucidation of the oxygen precipitation in highly doped silicon. In the study of the early phases of the oxygen precipitation boron-oxygen complexes and their kinetics could be indirectly detected. These arise already during the cooling of the crystal and can be destroyed by subsequent temperature processes. The formation of the here as BO assumed species during the cooling after the silicon crystal fabrication could be numerically reproduced. Furthermore the study of early precipitation phases by means of neutron small angle scattering a maximum of the oxygen precipitation at {rho}=9 m{omega}cm. It could be shown that the decreasing of this at increasing boron concentration can be most probably reduced to boron precipitations. Furthermore it could be shown that after a tempering time of 24 hours at 700 C in silicon with {rho}=9 m{omega}cm platelet-shaped precipitates form. By the study of the precipitate growth could be shown that also in this phase the oxygen precipitation in silicon is strongest with a specific resistance of {rho}=9 m{omega}cm. By means of FTIR spectroscopy a new absorption band at a wave number of 1038 cm{sup -1} was found, which could be assigned to a boron species. By different experiments it is considered as probable that at this species it deals with BI respectively B{sub 2}I complexes.

  3. Current application of high flow oxygen nasal cannula in acute hypoxemic respiratory failure in the emergency department

    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.

  4. Study of the corrosion of metallic coatings and alloys containing aluminum in a mixed atmosphere - sulphur, oxygen - at high temperatures

    Fellmann, Daniel

    1982-01-01

    The objective of this research thesis is the development of materials for a sulphur experimental loop allowing the thermodynamic properties of such an energy cycle to be checked. As solutions must comply with industrial methods, rare materials are excluded as they are too expensive or difficult to implement. Iron-based materials have been tested but could not have at the same time a good corrosion resistance and high temperature forming and mechanical toughness properties. Therefore, metallic coatings have been chosen, specifically alumina. After having reported a bibliographical study on corrosion by sulphur vapour and by oxygen and by sulphur-oxygen, the author presents the experimental materials and methods. Then, the author reports the study of mixed corrosion (by sulphur and oxygen together) of metallic alloys (ferritic and austeno-ferritic alloys, aluminium and titanium alloys), and of the corrosion of FeAlx coatings, of AlTix alloys [fr

  5. Oxygen dependency of porfiromycin cytotoxicity

    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

  6. Heliox delivered by high flow nasal cannula improves oxygenation in infants with respiratory syncytial virus acute bronchiolitis

    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.

  7. High impact of uranyl ions on carrying-releasing oxygen capability of hemoglobin-based blood substitutes

    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)

  8. Antioxidants keep the potentially probiotic but highly oxygen-sensitive human gut bacterium Faecalibacterium prausnitzii alive at ambient air.

    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.

  9. A high precision method for quantitative measurements of reactive oxygen species in frozen biopsies.

    Kirsti Berg

    Full Text Available OBJECTIVE: An electron paramagnetic resonance (EPR technique using the spin probe cyclic hydroxylamine 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine (CMH was introduced as a versatile method for high precision quantification of reactive oxygen species, including the superoxide radical in frozen biological samples such as cell suspensions, blood or biopsies. MATERIALS AND METHODS: Loss of measurement precision and accuracy due to variations in sample size and shape were minimized by assembling the sample in a well-defined volume. Measurement was carried out at low temperature (150 K using a nitrogen flow Dewar. The signal intensity was measured from the EPR 1st derivative amplitude, and related to a sample, 3-carboxy-proxyl (CP• with known spin concentration. RESULTS: The absolute spin concentration could be quantified with a precision and accuracy better than ±10 µM (k = 1. The spin concentration of samples stored at -80°C could be reproduced after 6 months of storage well within the same error estimate. CONCLUSION: The absolute spin concentration in wet biological samples such as biopsies, water solutions and cell cultures could be quantified with higher precision and accuracy than normally achievable using common techniques such as flat cells, tissue cells and various capillary tubes. In addition; biological samples could be collected and stored for future incubation with spin probe, and also further stored up to at least six months before EPR analysis, without loss of signal intensity. This opens for the possibility to store and transport incubated biological samples with known accuracy of the spin concentration over time.

  10. High-resolution conodont oxygen isotope record of Ordovician climate change

    Chen, J.; Chen, Z.; Algeo, T. J.

    2013-12-01

    The Ordovician Period was characterized by several major events, including a prolonged 'super greenhouse' during the Early Ordovician, the 'Great Ordovician Biodiversification Event (GOBE)' of the Middle and early Late Ordovician, and the Hirnantian ice age and mass extinction of the latest Ordovician (Webby et al., 2004, The Great Ordovician Biodiversification Event, Columbia University Press). The cause of the rapid diversification of marine invertebrates during the GOBE is not clear, however, and several scenarios have been proposed including widespread development of shallow cratonic seas, strong magmatic and tectonic activity, and climate moderation. In order to investigate relationships between climate change and marine ecosystem evolution during the Ordovician, we measured the oxygen isotopic composition of single coniform conodonts using a Cameca secondary ion mass spectrometer. Our δ18O profile shows a shift at the Early/Middle Ordovician transition that is indicative of a rapid 6 to 8 °C cooling. This cooling event marks the termination of the Early Ordovician 'super greenhouse' and may have established cooler tropical seawater temperatures that were more favorable for invertebrate animals, setting the stage for the GOBE. Additional cooling episodes occurred during the early Sandbian, early Katian, and Hirnantian, the last culminating in a short-lived (extinction. Our results differ from those of Trotter et al. (2008, 'Did cooling oceans trigger Ordovician biodiversification? Evidence from conodont thermometry,' Science 321:550-554). Instead of a slow, protracted cooling through the Early and Middle Ordovician, our high-resolution record shows that cooling occurred in several discrete steps, with the largest step being at the Early/Middle Ordovician transition.

  11. Randomized Comparison of Helmet CPAP Versus High-Flow Nasal Cannula Oxygen in Pediatric Respiratory Distress.

    Vitaliti, Giovanna; Vitaliti, Maria Concetta; Finocchiaro, Maria Carla; Di Stefano, Vita Antonella; Pavone, Piero; Matin, Nassim; Motamed-Gorji, Nazgol; Lubrano, Riccardo; Falsaperla, Raffaele

    2017-08-01

    The current study aimed to compare the efficacy and safety of 2 noninvasive respiratory support methods, which included helmet CPAP and high-flow nasal cannula (HFNC) in children with respiratory distress admitted to a pediatric intermediate care unit. This study was a prospective observational study conducted on children with respiratory distress (age 1-24 months) who were admitted to our acute and emergency operative unit. All included subjects were randomly treated with helmet CPAP or HFNC in a 1:1 fashion until their clinical picture, oxygen saturation, and arterial blood gas (ABG) parameters resolved. The efficiencies of helmet CPAP and HFNC were evaluated by breathing frequency, S pO 2 , ABG pH, ABG P aCO 2 , ABG P aO 2 , and P aO 2 /F IO 2 , recorded once at baseline and then after 1 and 6 h of treatment. Both noninvasive respiratory support modalities were compared with a control group of subjects with respiratory distress under standard therapeutic pharmaceutical protocols. We found that both helmet CPAP and HFNC were efficient in improving the clinical conditions of subjects with mild-to-moderate respiratory distress, although clinical response to helmet CPAP was more efficient and rapid compared with HFNC. Children who received respiratory support had a better clinical course in terms of hospitalization, days of intravenous rehydration therapy, and days of drug administration compared with the control group ( P CPAP and HFNC in respiratory distress resolution in a pediatric intermediate care setting. It aims to identify the most efficient treatment to avoid pediatric ICU admissions and endotracheal intubation and reduce the administration of drugs and days of hospitalization. Copyright © 2017 by Daedalus Enterprises.

  12. Highly acid-durable carbon coated Co3O4 nanoarrays as efficient oxygen evolution electrocatalysts

    Yang, Xiulin; Li, Henan; Lu, Ang-Yu; Min, Shixiong; Idriss, Zacharie; Hedhili, Mohamed N.; Huang, Kuo-Wei; Idriss, Hicham; Li, Lain-Jong

    2016-01-01

    Most oxygen evolution reaction (OER) electrocatalysts are not stable in corrosive acids. Even the expensive RuO2 or IrO2, the most acid-resistant oxides, can be dissolved at an oxidative potential. Herein, we realize that the failures of OER catalysts are mostly caused by the weak interface between catalysts and the substrates. Hence, the study of the interface structure between catalysts and substrates is critical. In this work, we observe that the cheap OER catalysts Co3O4 can be more durable than the state-of-the-art RuO2 if the interface quality is good enough. The Co3O4 nanosheets deposited on carbon paper (Co3O4/CP) is prepared by electroplating of Co-species and followed by a two-step calcination process. The 1st step occurs in vacuum in order to maintain the surface integrity of the carbon paper and converts Co-species to Co(II)O. The 2nd step is a calcination in ambient conditions which enables the complete transformation of Co(II)O to Co3O4 without degrading the mechanical strength of the Co3O4-CP interface. Equally important, an in situ formation of a layer of amorphous carbon on top of Co3O4 further enhances the OER catalyst stability. Therefore, these key advances make the Co3O4 catalyst highly active toward the OER in 0.5 M H2SO4 with a small overpotential (370 mV), to reach 10 mA/cm2. The observed long lifetime for 86.8 h at a constant current density of 100 mA/cm2, is among the best of the reported in literature so far, even longer than the state-of-art RuO2 on CP. Overall, our study provides a new insight and methodology for the construction of a high-performance and high stability OER electrocatalysts in corrosive acidic environments.

  13. Highly acid-durable carbon coated Co3O4 nanoarrays as efficient oxygen evolution electrocatalysts

    Yang, Xiulin

    2016-04-21

    Most oxygen evolution reaction (OER) electrocatalysts are not stable in corrosive acids. Even the expensive RuO2 or IrO2, the most acid-resistant oxides, can be dissolved at an oxidative potential. Herein, we realize that the failures of OER catalysts are mostly caused by the weak interface between catalysts and the substrates. Hence, the study of the interface structure between catalysts and substrates is critical. In this work, we observe that the cheap OER catalysts Co3O4 can be more durable than the state-of-the-art RuO2 if the interface quality is good enough. The Co3O4 nanosheets deposited on carbon paper (Co3O4/CP) is prepared by electroplating of Co-species and followed by a two-step calcination process. The 1st step occurs in vacuum in order to maintain the surface integrity of the carbon paper and converts Co-species to Co(II)O. The 2nd step is a calcination in ambient conditions which enables the complete transformation of Co(II)O to Co3O4 without degrading the mechanical strength of the Co3O4-CP interface. Equally important, an in situ formation of a layer of amorphous carbon on top of Co3O4 further enhances the OER catalyst stability. Therefore, these key advances make the Co3O4 catalyst highly active toward the OER in 0.5 M H2SO4 with a small overpotential (370 mV), to reach 10 mA/cm2. The observed long lifetime for 86.8 h at a constant current density of 100 mA/cm2, is among the best of the reported in literature so far, even longer than the state-of-art RuO2 on CP. Overall, our study provides a new insight and methodology for the construction of a high-performance and high stability OER electrocatalysts in corrosive acidic environments.

  14. Detonation mode and frequency analysis under high loss conditions for stoichiometric propane-oxygen

    Jackson, Scott

    2016-03-24

    The propagation characteristics of galloping detonations were quantified with a high-time-resolution velocity diagnostic. Combustion waves were initiated in 30-m lengths of 4.1-mm inner diameter transparent tubing filled with stoichiometric propane-oxygen mixtures. Chemiluminescence from the resulting waves was imaged to determine the luminous wave front position and velocity every 83.3 μ. As the mixture initial pressure was decreased from 20 to 7 kPa, the wave was observed to become increasingly unsteady and transition from steady detonation to a galloping detonation. While wave velocities averaged over the full tube length smoothly decreased with initial pressure down to half of the Chapman-Jouguet detonation velocity (DCJ) at the quenching limit, the actual propagation mechanism was seen to be a galloping wave with a cycle period of approximately 1.0 ms, corresponding to a cycle length of 1.3-2.0 m or 317-488 tube diameters depending on the average wave speed. The long test section length of 7300 tube diameters allowed observation of up to 20 galloping cycles, allowing for statistical analysis of the wave dynamics. In the galloping regime, a bimodal velocity distribution was observed with peaks centered near 0.4 DCJ and 0.95 DCJ. Decreasing initial pressure increasingly favored the low velocity mode. Galloping frequencies ranged from 0.8 to 1.0 kHz and were insensitive to initial mixture pressure. Wave deflagration-to-detonation transition and detonation failure trajectories were found to be repeatable in a given test and also across different initial mixture pressures. The temporal duration of wave dwell at the low and high velocity modes during galloping was also quantified. It was found that the mean wave dwell duration in the low velocity mode was a weak function of initial mixture pressure, while the mean dwell time in the high velocity mode depended exponentially on initial mixture pressure. Analysis of the velocity histories using dynamical systems ideas

  15. The surface structure of SrTiO3 at high temperatures under influence of oxygen

    Hesselberth, M. B. S.; Molen, S. J. van der; Aarts, J.

    2014-01-01

    We use low energy electron microscopy to investigate the structure of the SrTiO 3 (001) surface at elevated temperatures and different oxygen pressures. Upon varying the temperature between 500 °C and 900 °C in oxygen pressures ranging from 10 −9 millibar to 10 −4 millibar, two surface transitions are found to be present. The lower temperature (1 × 1) → (2 × 1) transition that is known to occur in ultrahigh vacuum can be reversed by increasing the oxygen pressure. At higher temperatures, we observe a (2 × 1) → disordered (1 × 1) transition which is irreversible in the experimental parameter range. The observations are expected to have a strong bearing on the growth of interface structures

  16. Tension pneumocephalus: Mount Fuji sign

    Pulastya Sanyal

    2015-01-01

    Full Text Available A 13-year-old male was operated for a space occupying lesion in the brain. A noncontrast computed tomography scan done in the late postoperative period showed massive subdural air collection causing compression of bilateral frontal lobes with widening of interhemispheric fissure and the frontal lobes acquiring a peak like configuration - causing tension pneumocephalus-"Mount Fuji sign." Tension pneumocephalus occurs when air enters the extradural or intradural spaces in sufficient volume to exert a mass or pressure effect on the brain, leading to brain herniation. Tension pneumocephalus is a surgical emergency, which needs immediate intervention in the form of decompression of the cranial cavity by a burr hole or needle aspiration. The Mount Fuji sign differentiates tension pneumocephalus from pneumocephalus.

  17. High temperature thermodynamics of solutions of oxygen in zirconium and hafnium

    Boureau, G.; Gerdanian, P.

    1984-01-01

    The Tian-Calvet microcalorimetric method has been applied to the determination at 1323 Kelvin of ΔH(O 2 ), the partial molar enthalpy of mixing of oxygen in zirconium and in hafnium. No measurable departure from Henry's law has been found for dilute solutions (ratio oxygen over metal smaller than 0.1). For concentrated solutions repulsive interactions are found in agreement with the existence of ordered structures at lower temperatures. The domain of homogeneity of zirconium has been found larger than previously assumed. (author)

  18. Effect of High-Flow Nasal Cannula versus Conventional Oxygen Therapy for Patients with Thoracoscopic Lobectomy after Extubation

    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.

  19. Micro-texturing into DLC/diamond coated molds and dies via high density oxygen plasma etching

    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.

  20. Myocardial blood flow and its transit time, oxygen utilization, and efficiency of highly endurance-trained human heart.

    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.