IMPACT OF OXYGEN CONCENTRATION ON ZEBRA MUSSEL MORTALITY

Energy Technology Data Exchange (ETDEWEB)

Daniel P. Molloy

2003-01-27

These tests have indicated that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels in environments having dissolved oxygen (DO) concentrations ranging from very low to very high. The results suggest that the highest mussel kill can be achieved in moderately to highly aerated environments, while kill may be 0-20% lower under conditions of very low oxygen. For example, under highly oxygenated conditions 97% kill was achieved while conditions having low DO produced 79% mussel kill. Service water measured in a local power plant indicated that DO concentrations were in the range of 8-9 ppm (e.g., highly aerated) within their pipes. Therefore, we will not expect to see decreases in the efficacy of CL0145A treatments due to oxygen levels within such power plant pipes.

IMPACT OF OXYGEN CONCENTRATION ON ZEBRA MUSSEL MORTALITY

International Nuclear Information System (INIS)

Molloy, Daniel P.

2003-01-01

These tests have indicated that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels in environments having dissolved oxygen (DO) concentrations ranging from very low to very high. The results suggest that the highest mussel kill can be achieved in moderately to highly aerated environments, while kill may be 0-20% lower under conditions of very low oxygen. For example, under highly oxygenated conditions 97% kill was achieved while conditions having low DO produced 79% mussel kill. Service water measured in a local power plant indicated that DO concentrations were in the range of 8-9 ppm (e.g., highly aerated) within their pipes. Therefore, we will not expect to see decreases in the efficacy of CL0145A treatments due to oxygen levels within such power plant pipes

Reinforcement corrosion in alkaline chloride media with reduced oxygen concentrations

International Nuclear Information System (INIS)

Andrade, C.; Fullea, J.; Toro, L.; Martinez, I.; Rebolledo, N.

2013-01-01

It is commonly considered that the corrosion of steel in concrete is controlled by the oxygen content of the pore solution and there are service life models that relate the corrosion rate to the amount of oxygen. It is also commonly believed that in water saturated conditions the oxygen content in the pores is negligible and that underwater there is no risk of depassivation and the corrosion rate is very low. However, the available data on corrosion rates in immersed conditions do not indicate such performance; on the contrary corrosion develops when sufficient chloride reaches the reinforcement. In the present paper, results are presented for tests performed in alkaline chloride solutions that were purged with nitrogen to reduce the oxygen content. The results indicate that at very low oxygen concentrations, corrosion may develop in the presence of chlorides. The presence or absence of corrosion is influenced by the amount of chloride, the corrosion potential and the steel surface condition. (authors)

Dislocation behavior of surface-oxygen-concentration controlled Si wafers

International Nuclear Information System (INIS)

Asazu, Hirotada; Takeuchi, Shotaro; Sannai, Hiroya; Sudo, Haruo; Araki, Koji; Nakamura, Yoshiaki; Izunome, Koji; Sakai, Akira

2014-01-01

We have investigated dislocation behavior in the surface area of surface-oxygen-concentration controlled Si wafers treated by a high temperature rapid thermal oxidation (HT-RTO). The HT-RTO process allows us to precisely control the interstitial oxygen concentration ([O i ]) in the surface area of the Si wafers. Sizes of rosette patterns, generated by nano-indentation and subsequent thermal annealing at 900 °C for 1 h, were measured for the Si wafers with various [O i ]. It was found that the rosette size decreases in proportion to the − 0.25 power of [O i ] in the surface area of the Si wafers, which were higher than [O i ] of 1 × 10 17 atoms/cm 3 . On the other hand, [O i ] of lower than 1 × 10 17 atoms/cm 3 did not affect the rosette size very much. These experimental results demonstrate the ability of the HT-RTO process to suppress the dislocation movements in the surface area of the Si wafer. - Highlights: • Surface-oxygen-concentration controlled Si wafers have been made. • The oxygen concentration was controlled by high temperature rapid thermal oxidation. • Dislocation behavior in the surface area of the Si wafers has been investigated. • Rosette size decreased with increasing of interstitial oxygen atoms. • The interstitial oxygen atoms have a pinning effect of dislocations at the surface

Application of Nanosize Zeolite Molecular Sieves for Medical Oxygen Concentration

Directory of Open Access Journals (Sweden)

Mingfei Pan

2017-07-01

Full Text Available The development of a portable oxygen concentrator is of prime significance for patients with respiratory problems. This paper presents a portable concentrator prototype design using the pressure/vacuum swing adsorption (PVSA cycle with a deep evacuation step (−0.82 barg instead of desorption with purge flow to simplify the oxygen production process. The output of the oxygen concentrator is a ~90 vol % enriched oxygen stream in a continuous adsorption and desorption cycle (cycle time ~90 s. The size of the adsorption column is 3 cm in diameter and 20 cm in length. A Li+ exchanged 13X nanosize zeolite is used as the adsorbent to selectively adsorb nitrogen from air. A dynamic model of the pressure and vacuum swing adsorption units was developed to study the pressurization and depressurization process inside the microporous area of nanosized zeolites. The describing equations were solved using COMSOL Multiphysics Chemical Engineering module. The output flow rate and oxygen concentration results from the simulation model were compared with the experimental data. Velocity and concentration profiles were obtained to study the adsorption process and optimize the operational parameters.

Radiation survival of cells from spheroids grown in different oxygen concentrations

International Nuclear Information System (INIS)

Franko, A.J.; Sutherland, R.M.

1979-01-01

The position of the internal, chronically hypoxic cells in spheroids was varied by alterations in the oxygen concentration in the growth medium. Such alterations were expected to cause large changes in the size of the radiobiologically hypoxic fraction. This was tested by growing and irradiating spheroids in oxygen concentrations between 5 and 20.3%, ensuring that the irradiation and growth conditions were as similar as possible. The survival curves appeared to be linear below a surviving fraction of 3 x 10 -2 , and the slopes were intermediate between the slopes of control curves for cells from spheroids irradiated in nitrogen or when fully oxygenated. Thus direct estimates of the hypoxic fractions could not be made. Two models of oxygen diffusion might explain the data. One model assumes that a large fraction of cells was fully hypoxic (radiobiologically) and that these internal, G 1 -confined, chronically hypoxic cells had a lower inherent radioresistance than the outer proliferating cells. Evidence was presented which indicated that this model was unlikely to be correct. The other model assumes that the inherent radioresistance was equal throughout the spheroid, and that the innermost cells died before the oxygen concentration was reduced sufficiently to cause full hypoxic protection. Theoretical survival curves based on this model were generated using the measured geometries ofthe spheroids and multitarget single-hit survival theory. Acceptable agreement with the postulate that the innermost cells of spheroids die at between 0.2 and 0.4% oxygen was obtained. These data may have implications regarding the relative contributions of chronic and acute hypoxia to the fraction of hypoxic cells in tumors

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

Science.gov (United States)

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.

Use of an oxygen concentrator in a Nigerian neonatal unit: economic implications and reliability.

Science.gov (United States)

Mokuolu, Olugbenga A; Ajayi, Oluade A

2002-09-01

A 3-year experience of using an oxygen concentrator in a Nigerian newborn unit and economic appraisal of its effectiveness is reported. The oxygen concentrator is a device that absorbs nitrogen from ambient air, with a resultant oxygen concentration of 85 to 95% at different flow rates. The oxygen concentrator met our oxygen needs which averaged 18 hours a day, and had a huge cost advantage over the oxygen cylinders. The cost of oxygen via cylinder for just one patient for a year exceeds the initial capital outlay for a concentrator. The Puritan-Bennett oxygen concentrator has a lifespan of at least 7 years and is virtually maintenance-free for the 1st 26,400 hours of use, after which some major components might need replacement. We conclude that in developing countries oxygen concentrators are a more cost-effective, reliable and convenient means of oxygen supply than oxygen cylinders, and recommend their use where there is a high demand for oxygen.

Evaluation of the Oxygen Concentrator Prototypes: Pressure Swing Adsorption Prototype and Electrochemical Prototype

Science.gov (United States)

Gilkey, Kelly M.; Olson, Sandra L.

2015-01-01

An oxygen concentrator is needed to provide enriched oxygen in support of medical contingency operations for future exploration human spaceflight programs. It would provide continuous oxygen to an ill or injured crew member in a closed cabin environment. Oxygen concentration technology is being pursued to concentrate oxygen from the ambient environment so oxygen as a consumable resource can be reduced. Because oxygen is a critical resource in manned spaceflight, using an oxygen concentrator to pull oxygen out of the ambient environment instead of using compressed oxygen can provide better optimization of resources. The overall goal of this project is to develop an oxygen concentrator module that minimizes the hardware mass, volume, and power footprint while still performing at the required clinical capabilities. Should a medical event occur that requires patient oxygenation, the release of 100 percent oxygen into a small closed cabin environment can rapidly raise oxygen levels to the vehicles fire limit. The use of an oxygen concentrator to enrich oxygen from the ambient air and concentrate it to the point where it can be used for medical purposes means no oxygen is needed from the ultra-high purity (99.5+% O2) oxygen reserve tanks. By not adding oxygen from compressed tanks to the cabin environment, oxygen levels can be kept below the vehicle fire limit thereby extending the duration of care provided to an oxygenated patient without environmental control system intervention to keep the cabin oxygen levels below the fire limits. The oxygen concentrator will be a Food and Drug Administration (FDA) clearable device. A demonstration unit for the International Space Station (ISS) is planned to verify the technology and provide oxygen capability. For the ISS, the demonstration unit should not exceed 10 kg (approximately 22 lb), which is the soft stowage mass limit for launch on resupply vehicles for the ISS. The unit's size should allow for transport within the

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

Energy Technology Data Exchange (ETDEWEB)

Sheard, Michael A., E-mail: msheard@chla.usc.edu [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Ghent, Matthew V., E-mail: mattghent@gmail.com [Department of Pathology, Keck School of Medicine, University of Southern California, Health Sciences Campus, Los Angeles, CA 90089 (United States); Cabral, Daniel J., E-mail: dcabral14@gmail.com [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); Lee, Joanne C., E-mail: joannebarnhart@gmail.com [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); Khankaldyyan, Vazgen, E-mail: khangaldian@yahoo.com [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Ji, Lingyun, E-mail: lingyun.ji@med.usc.edu [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Wu, Samuel Q., E-mail: swu@chla.usc.edu [Medical Genetics, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Kang, Min H., E-mail: min.kang@ttuhsc.edu [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); and others

2015-05-15

Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. - Highlights: • Establishing new ALL cell lines in 5% oxygen resulted in higher glycolytic expression and function. • Establishing new ALL cell lines in 5% oxygen resulted in higher proliferation and lower cell death. • The divergent metabolic phenotypes selected in 5% and 20% oxygen are semi-permanent.

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

International Nuclear Information System (INIS)

Sheard, Michael A.; Ghent, Matthew V.; Cabral, Daniel J.; Lee, Joanne C.; Khankaldyyan, Vazgen; Ji, Lingyun; Wu, Samuel Q.; Kang, Min H.

2015-01-01

Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. - Highlights: • Establishing new ALL cell lines in 5% oxygen resulted in higher glycolytic expression and function. • Establishing new ALL cell lines in 5% oxygen resulted in higher proliferation and lower cell death. • The divergent metabolic phenotypes selected in 5% and 20% oxygen are semi-permanent

The relation between oxygen saturation level and retionopathy of prematurity

Directory of Open Access Journals (Sweden)

Mohammad Gharavi Fard

2016-03-01

Full Text Available Introduction: Oxygen therapy used for preterm infant disease might be associated with oxygen toxicity or oxidative stress. The exact oxygen concentration to control and maintain the arterial oxygen saturation balance is not certainly clear. We aimed to compare the efficacy of higher or lower oxygen saturations on the development of severe retinopathy of prematurity which is a major cause of blindness in preterm neonates. Methods: PubMed was searched for obtaining the relevant articles. A total of seven articles were included after studying the titles, abstracts, and the full text of retrieved articles at initial search. Inclusion criteria were all the English language human clinical randomized controlled trials with no time limitation, which studied the efficacy of low versus high oxygen saturation measured by pulse oximetry in preterm infants.Result: It can be suggested that lower limits of oxygen saturations have higher efficacy at postmesetural age of ≤28 weeks in preterm neonates. This relation has been demonstrated in five large clinical trials including three Boost trials, COT, and Support.Discussion: Applying higher concentrations of oxygen supplementations at mesentural age ≥32 weeks reduced the development of retinopathy of prematurity. Lower concentrations of oxygen saturation decreased the incidence and the development of retinopathy of prematurity in preterm neonates while applied soon after the birth.Conclusions: Targeting levels of oxygen saturation in the low or high range should be performed cautiously with attention to the postmesentural age in preterm infants at the time of starting the procedures.

Oxygen diffusion-concentration in phospholipidic model membranes. An ESR-saturation study

International Nuclear Information System (INIS)

Vachon, A.; Lecomte, C.; Berleur, F.

1986-04-01

Fully hydrated liposomes of dipalmitoyl-phosphatidylcholine were labelled with 5 (or 7, 10, 12, 16)-doxyl stearic acid at pH 6 and 8, and studied by the continuous wave ESR-saturation technique. The ESR spectral magnitude depends on the hyperfrequency power P and on both T 1 and T 2 relaxation times. Saturation, i.e. the non linearity of the spectral magnitude plotted versus √P can be quantified by a P1/2 parameter (power at which the signal is half as great as it would be without saturation). If we assume T 2 weakly modified by spin exchange between paramagnetic spin probe and oxygen in triplet state, P1/2 is inversely proportional to T 1 , and becomes a sensitive parameter to appreciate the oxygen transport (oxygen diffusion-concentration product) inside the bilayers. According to the DPPC bilayer phase transition diagrams, P1/2 (oxygen diffusion-concentration) is related to the thermodynamic state of the membrane. This technique provides further informations on a particular property of a radioprotective agent, cysteamine, which seems to inhibit spin-triplet exchange and hence maximizes T 1 (minimizes P1/2). Since radioprotective agents are known to act by scavenging radiation-induced free radicals and by inhibiting oxygen-dependent free radical processes, such a result may contribute to elucidate radioprotecting mechanisms

Determination of the Minimal Fresh Gas Flow to Maintain a Therapeutic Inspired Oxygen Concentration in a Semi-Closed Anesthesia Circle System Using an Oxygen Concentrator as the Oxygen Source

National Research Council Canada - National Science Library

Grano, Joan

2001-01-01

The purpose of this study was to determine the rate of oxygen dilution, resulting from argon accumulation, using 3 low fresh gas flow rates using an oxygen concentrator in a semi-closed anesthesia circle system...

Sulfide-inhibition of mitochondrial respiration at very low oxygen concentrations.

Science.gov (United States)

Matallo, J; Vogt, J; McCook, O; Wachter, U; Tillmans, F; Groeger, M; Szabo, C; Georgieff, M; Radermacher, P; Calzia, E

2014-09-15

Our aim was to study the ability of an immortalized cell line (AMJ2-C11) to sustain aerobic cell respiration at decreasing oxygen concentrations under continuous sulfide exposure. We assumed that the rate of elimination of sulfide through the pathway linked to the mitochondrial respiratory chain and therefore operating under aerobic conditions, should decrease with limiting oxygen concentrations. Thus, sulfide's inhibition of cellular respiration would occur faster under continuous sulfide exposure when the oxygen concentration is in the very low range. The experiments were performed with an O2K-oxygraph (Oroboros Instruments) by suspending 0.5-1×10(6) cells in 2 ml of continuously stirred respiration medium at 37 °C and calculating the oxygen flux (JO2) as the negative derivative of the oxygen concentration in the medium. The cells were studied in two different metabolic states, namely under normal physiologic respiration (1) and after uncoupling of mitochondrial respiration (2). Oxygen concentration was controlled by means of a titration-injection pump, resulting in average concentration values of 0.73±0.05 μM, 3.1±0.2 μM, and 6.2±0.2 μM. Simultaneously we injected a 2 mM Na2S solution at a continuous rate of 10 μl/s in order to quantify the titration-time required to reduce the JO2 to 50% of the initial respiratory activity. Under the lowest oxygen concentration this effect was achieved after 3.5 [0.3;3.5] and 11.7 [6.2;21.2]min in the uncoupled and coupled state, respectively. This time was statistically significantly shorter when compared to the intermediate and the highest O2 concentrations tested, which yielded values of 24.6 [15.5;28.1]min (coupled) and 35.9 [27.4;59.2]min (uncoupled), as well as 42.4 [27.5;42.4]min (coupled) and 51.5 [46.4;51.7]min (uncoupled). All data are medians [25%, and 75% percentiles]. Our results confirm that the onset of inhibition of cell respiration by sulfide occurs earlier under a continuous exposure when approaching

Relationship between oxygen concentration, respiration and filtration rate in blue mussel Mytilus edulis

Science.gov (United States)

Tang, Baojun; Riisgård, Hans Ulrik

2018-03-01

The large water-pumping and particle-capturing gills of the filter-feeding blue mussel Mytilus edulis are oversized for respiratory purposes. Consequently, the oxygen uptake rate of the mussel has been suggested to be rather insensitive to decreasing oxygen concentrations in the ambient water, since the diffusion rate of oxygen from water flowing through the mussel determines oxygen uptake. We tested this hypothesis by measuring the oxygen uptake in mussels exposed to various oxygen concentrations. These concentrations were established via N2-bubbling of the water in a respiration chamber with mussels fed algal cells to stimulate fully opening of the valves. It was found that mussels exposed to oxygen concentrations decreasing from 9 to 2 mg O2/L resulted in a slow but significant reduction in the respiration rate, while the filtration rate remained high and constant. Thus, a decrease of oxygen concentration by 78% only resulted in a 25% decrease in respiration rate. However, at oxygen concentrations below 2 mg O2/L M. edulis responded by gradually closing its valves, resulting in a rapid decrease of filtration rate, concurrent with a rapid reduction of respiration rate. These observations indicated that M. edulis is no longer able to maintain its normal aerobic metabolism at oxygen concentration below 2 mg O2/L, and there seems to be an energy-saving mechanism in bivalve molluscs to strongly reduce their activity when exposed to low oxygen conditions.

Monitoring and measurement of oxygen concentrations in liquid sodium

International Nuclear Information System (INIS)

Smith, D.L.

1976-01-01

The measurement of oxygen concentrations in sodium at levels of interest for LMFBR applications is reviewed. Additional data are presented to support the validity of the vanadium-equilibration method as a reference for determination of oxygen concentrations in sodium at levels equal to or less than 15 ppM. Operating experience with electrochemical oxygen meters that have a thoria-yttria electrolyte and a Na--Na 2 O reference electrode is described. Meter lifetimes in excess of one year have generally been achieved for operating temperatures of 352 and 402 0 C, and fairly stable emfs have been observed for periods of several months. 7 fig, 21 references

Estimate of oxygen consumption and intracellular zinc concentration of human spermatozoa in relation to motility.

Science.gov (United States)

Henkel, Ralf R; Defosse, Kerstin; Koyro, Hans-Wilhelm; Weissmann, Norbert; Schill, Wolf-Bernhard

2003-03-01

To investigate the human sperm oxygen/energy consumption and zinc content in relation to motility. In washed spermatozoa from 67 ejaculates, the oxygen consumption was determined. Following calculation of the total oxygen consumed by the Ideal Gas Law, the energy consumption of spermatozoa was calculated. In addition, the zinc content of the sperm was determined using an atomic absorption spectrometer. The resulting data were correlated to the vitality and motility. The oxygen consumption averaged 0.24 micromol/10(6) sperm x 24h, 0.28 micromol/10(6) live sperm x 24h and 0.85 micromol/10(6) live motile sperm x 24h. Further calculations revealed that sperm motility was the most energy consuming process (164.31 mJ/10(6) motile spermatozoa x 24h), while the oxygen consumption of the total spermatozoa was 46.06 mJ/10(6) spermatozoa x 24h. The correlation of the oxygen/energy consumption and zinc content with motility showed significant negative correlations (r= -0.759; P<0.0001 and r=-0.441; P<0.0001, respectively). However, when correlating sperm energy consumption with the zinc content, a significant positive relation (r=0.323; P=0.01) was observed. Poorly motile sperm are actually wasting the available energy. Moreover, our data clearly support the "Geometric Clutch Model" of the axoneme function and demonstrate the importance of the outer dense fibers for the generation of sperm motility, especially progressive motility.

About Error in Measuring Oxygen Concentration by Solid-Electrolyte Sensors

Directory of Open Access Journals (Sweden)

V. I. Nazarov

2008-01-01

Full Text Available The paper evaluates additional errors while measuring oxygen concentration in a gas mixture by a solid-electrolyte cell. Experimental dependences of additional errors caused by changes in temperature in a sensor zone, discharge of gas mixture supplied to a sensor zone, partial pressure in the gas mixture and fluctuations in oxygen concentrations in the air.

Methane oxidation and formation of EPS in compost: effect of oxygen concentration

International Nuclear Information System (INIS)

Wilshusen, J.H.; Hettiaratchi, J.P.A.; Visscher, A. de; Saint-Fort, R.

2004-01-01

Oxygen concentration plays an important role in the regulation of methane oxidation and the microbial ecology of methanotrophs. However, this effect is still poorly quantified in soil and compost ecosystems. The effect of oxygen on the formation of exopolymeric substances (EPS) is as yet unknown. We studied the effect of oxygen on the evolution of methanotrophic activity. At both high and low oxygen concentrations, peak activity was observed twice within a period of 6 months. Phospholipid fatty acid analysis showed that there was a shift from type I to type II methanotrophs during this period. At high oxygen concentration, EPS production was about 250% of the amount at low oxygen concentration. It is hypothesized that EPS serves as a carbon cycling mechanism for type I methanotrophs when inorganic nitrogen is limiting. Simultaneously, EPS stimulates nitrogenase activity in type II methanotrophs by creating oxygen-depleted zones. The kinetic results were incorporated in a simulation model for gas transport and methane oxidation in a passively aerated biofilter. Comparison between the model and experimental data showed that, besides acting as a micro-scale diffusion barrier, EPS can act as a barrier to macro-scale diffusion, reducing the performance of such biofilters. - 1.5% oxygen resulted in a slightly higher and more stable methane oxidation activity

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

International Nuclear Information System (INIS)

Casse, G.; Glaser, M.; Lemeilleur, F.; Ruzin, A.; Wegrzecki, M.

1999-01-01

The tolerance of silicon detectors to hadron irradiation can be improved by the introduction of a high concentration of oxygen into the starting material. High-resistivity Floating-Zone (FZ) silicon is required for detectors used in particle physics applications. A significantly high oxygen concentration (>10 17 atoms cm -3 ) cannot readily be achieved during the FZ silicon refinement. The diffusion of oxygen at elevated temperatures from a SiO 2 layer grown on both sides of a silicon wafer is a simple and effective technique to achieve high and uniform concentrations of oxygen throughout the bulk of a 300 μm thick silicon wafer

Combustion of pulverized fuel under oxycoal conditions at low oxygen concentrations

Energy Technology Data Exchange (ETDEWEB)

Toporov D.; Foerster M.; Kneer R. [RWTH Aachen University, Aachen (Germany). Institute of Heat and Mass Transfer

2007-07-01

Oxycoal combustion followed by post-combustion CO{sub 2} sequestration has gained justified interest as an option for significant and relatively quick reduction of emissions from fossil fuel power generation, while taking advantage of the existing power plant infrastructure. Burning pulverised coal in a mixture of CO{sub 2}/O{sub 2} instead of air, however, will lead to modified distributions of temperature, species, and radiation fluxes inside the combustion chamber causing a retroaction on the homogeneous and heterogeneous reactions. Utilizing a burner design, which was optimised for coal combustion in air, for oxycoal combustion will lead to flame instability and poor burnout. Stabilisation of the combustion process can be obtained by: i) an increased oxygen concentration (more than 21% vol.) in the oxidiser mixture, thus achieving similar reaction rates and temperature levels to a pulverised fuel-air flame without significant changes to the flame aerodynamics. ii) modifications to the burner aerodynamics, as presented here. The results in this study are obtained in the frame of OXYCOAL-AC, the research project, having the aim to burn a pulverised coal in a CO{sub 2}/O{sub 2}-atmosphere with oxygen, produced from high-temperature ceramic membrane thus leading to higher efficiency of the whole oxycoal process. Numerical and experimental investigations of a stable oxycoal flame, obtained with {le} 21% oxygen concentration in the burning mixture at the RWTH test facility are reported. Two different burner designs are considered, conclusions concerning the achievement of a stable oxycoal flame at O{sub 2} volume concentrations equal and less to the one of oxygen in air are derived. 8 refs., 7 figs., 1 tab.

Influence of oxygen partial pressure on defect concentrations and on oxygen diffusion in UO2+x

International Nuclear Information System (INIS)

Pizzi, Elisabetta

2013-01-01

The hyper-stoichiometric uranium dioxide (UO 2+x ) is stable over a wide range of temperature and compositions. Such variations of composition and the eventual presence of doping elements or impurities lead to a variation of anionic and electronic defect concentrations. Moreover, many properties of this material are affected by its composition modifications, in particular their atomic transport properties. Firstly we developed a point defect model to evaluate the dependence of the electronic and oxygen defect concentrations upon temperature, equilibrium oxygen partial pressure and impurity content. The physical constants of the model, in particular the equilibrium constants of the defect formation reactions were determined from deviation from stoichiometry and electrical conductivity measurements of literature. This work enabled us to interpret our measures of conductivity, oxygen chemical and self- diffusion coefficients. From a quantitative standpoint, the analysis of our experimental results allows to evaluate the oxygen interstitial diffusion coefficient but also its formation energy. Moreover, an estimate of oxygen di-interstitial formation energy is also provided. Presence of oxygen clusters leads oxygen self- and chemical diffusion to decrease. X-ray Absorption Spectroscopy characterization shows the presence of the same defect in the entire deviation from stoichiometry studied, confirming the approach used to develop the model. (author) [fr

Radiation-induced lipid peroxidation: influence of oxygen concentration and membrane lipid composition

International Nuclear Information System (INIS)

Wolters, H.; Tilburg, C.A.M. van; Konings, A.W.T.

1987-01-01

Radiation -induced lipid peroxidation phospholipid liposomes was investigated in terms of its dependence on lipid composition and oxygen concentration. Non-peroxidizable lipid incorporated in the liposomes reduced the rate of peroxidation of the peroxidizable phospholipid acyl chains, possibly by restricting the length of chain reactions. The latter effect is believed to be caused by interference of the non-peroxidizable lipids in the bilayer. At low oxygen concentration lipid peroxidation was reduced. The cause of this limited peroxidation may be a reduced number of radical initiation reactions possibly involving oxygen-derived superoxide radicals. Killing of proliferating mammalian cells, irradiated at oxygen concentrations ranging from 0 to 100%, appeared to be independent of the concentration of peroxidizable phospholipids in the cell membranes. This indicates that lipid peroxidation is not the determining process in radiation-induced reproductive cell death. (author)

Correlation of Oxygenated Hemoglobin Concentration and Psychophysical Amount on Speech Recognition

Science.gov (United States)

Nozawa, Akio; Ide, Hideto

The subjective understanding on oral language understanding task is quantitatively evaluated by the fluctuation of oxygenated hemoglobin concentration measured by the near-infrared spectroscopy. The English listening comprehension test wihch consists of two difficulty level was executed by 4 subjects during the measurement. A significant correlation was found between the subjective understanding and the fluctuation of oxygenated hemoglobin concentration.

Characterization of reaction products in sodium-oxygen batteries : An electrolyte concentration study

OpenAIRE

Hedman, Jonas

2017-01-01

In this thesis, the discharge products formed at the cathode and the performance and cell chemistry of sodium-oxygen batteries have been studied. This was carried out using different NaOTf salt concentrations. The influence of different salt concentrations on sodium-oxygen batteries was investigated since it has been shown that increasing the salt concentration beyond conventional concentrations could result in advantages such as increased stability of the electrolytes towards decomposition, ...

Effects of Hyperoxia on Oxygen-Related Inflammation with a Focus on Obesity

Directory of Open Access Journals (Sweden)

Pedro González-Muniesa

2016-01-01

Full Text Available Several studies have shown a pathological oxygenation (hypoxia/hyperoxia on the adipose tissue in obese subjects. Additionally, the excess of body weight is often accompanied by a state of chronic low-degree inflammation. The inflammation phenomenon is a complex biological response mounted by tissues to combat injurious stimuli in order to maintain cell homeostasis. Furthermore, it is believed that the abnormal oxygen partial pressure occurring in adipose tissue is involved in triggering inflammatory processes. In this context, oxygen is used in modern medicine as a treatment for several diseases with inflammatory components. Thus, hyperbaric oxygenation has demonstrated beneficial effects, apart from improving local tissue oxygenation, on promoting angiogenesis, wound healing, providing neuroprotection, facilitating glucose uptake, appetite, and others. Nevertheless, an excessive hyperoxia exposure can lead to deleterious effects such as oxidative stress, pulmonary edema, and maybe inflammation. Interestingly, some of these favorable outcomes occur under high and low oxygen concentrations. Hereby, we review a potential therapeutic approach to the management of obesity as well as the oxygen-related inflammation accompanying expanded adipose tissue, based on elevated oxygen concentrations. To conclude, we highlight at the end of this review some areas that need further clarification.

Fluorescence measurement of atomic oxygen concentration in a dielectric barrier discharge

Science.gov (United States)

Dvořák, P.; Mrkvičková, M.; Obrusník, A.; Kratzer, J.; Dědina, J.; Procházka, V.

2017-06-01

Concentration of atomic oxygen was measured in a volume dielectric barrier discharge (DBD) ignited in mixtures of Ar + O2(+ H2) at atmospheric pressure. Two-photon absorption laser induced fluorescence (TALIF) of atomic oxygen was used and this method was calibrated by TALIF of Xe in a mixture of argon and a trace of xenon. The calibration was performed at atmospheric pressure and it was shown that quenching by three-body collisions has negligible effect on the life time of excited Xe atoms. The concentration of atomic oxygen in the DBD was around 1021 m-3 and it was stable during the whole discharge period. The concentration did not depend much on the electric power delivered to the discharge provided that the power was sufficiently high so that the visible discharge filled the whole reactor volume. Both the addition of hydrogen or replacing of argon by helium led to a significant decrease of atomic oxygen concentration. The TALIF measurements of O concentration levels in the DBD plasma performed in this work are made use of e.g. in the field analytical chemistry. The results contribute to understanding the processes of analyte hydride preconcentration and subsequent atomization in the field of trace element analysis where DBD plasma atomizers are employed.

Validation of NIRS in measuring tissue hemoglobin concentration and oxygen saturation on ex vivo and isolated limb models

Science.gov (United States)

Xu, Xiaorong; Zhu, Wen; Padival, Vikram; Xia, Mengna; Cheng, Xuefeng; Bush, Robin; Christenson, Linda; Chan, Tim; Doherty, Tim; Iatridis, Angelo

2003-07-01

Photonify"s tissue spectrometer uses Near-Infrared Spectroscopy for real-time, noninvasive measurement of hemoglobin concentration and oxygen saturation [SO2] of biological tissues. The technology was validated by a series of ex vivo and animal studies. In the ex vivo experiment, a close loop blood circulation system was built, precisely controlling the oxygen saturation and the hemoglobin concentration of a liquid phantom. Photonify"s tissue spectrometer was placed on the surface of the liquid phantom for real time measurement and compared with a gas analyzer, considered the gold standard to measure oxygen saturation and hemoglobin concentration. In the animal experiment, the right hind limb of each dog accepted onto the study was surgically removed. The limb was kept viable by connecting the femoral vein and artery to a blood-primed extracorporeal circuit. Different concentrations of hemoglobin were obtained by adding designated amount of saline solution into the perfusion circuit. Photonify"s tissue spectrometers measured oxygen saturation and hemoglobin concentration at various locations on the limb and compared with gas analyzer results. The test results demonstrated that Photonify"s tissue spectrometers were able to detect the relative changes in tissue oxygen saturation and hemoglobin concentration with a high linear correlation compared to the gas analyzer

Monitor hemoglobin concentration and oxygen saturation in living mouse tail using photoacoustic CT scanner

Science.gov (United States)

Liu, Bo; Kruger, Robert; Reinecke, Daniel; Stantz, Keith M.

2010-02-01

Purpose: The purpose of this study is to use PCT spectroscopy scanner to monitor the hemoglobin concentration and oxygen saturation change of living mouse by imaging the artery and veins in a mouse tail. Materials and Methods: One mouse tail was scanned using the PCT small animal scanner at the isosbestic wavelength (796nm) to obtain its hemoglobin concentration. Immediately after the scan, the mouse was euthanized and its blood was extracted from the heart. The true hemoglobin concentration was measured using a co-oximeter. Reconstruction correction algorithm to compensate the acoustic signal loss due to the existence of bone structure in the mouse tail was developed. After the correction, the hemoglobin concentration was calculated from the PCT images and compared with co-oximeter result. Next, one mouse were immobilized in the PCT scanner. Gas with different concentrations of oxygen was given to mouse to change the oxygen saturation. PCT tail vessel spectroscopy scans were performed 15 minutes after the introduction of gas. The oxygen saturation values were then calculated to monitor the oxygen saturation change of mouse. Results: The systematic error for hemoglobin concentration measurement was less than 5% based on preliminary analysis. Same correction technique was used for oxygen saturation calculation. After correction, the oxygen saturation level change matches the oxygen volume ratio change of the introduced gas. Conclusion: This living mouse tail experiment has shown that NIR PCT-spectroscopy can be used to monitor the oxygen saturation status in living small animals.

The effect of inhaling concentrated oxygen on performance during repeated anaerobic exercise

Directory of Open Access Journals (Sweden)

J Heller

2010-09-01

Full Text Available The objective of the pilot study was to test the effect of inhaling 99.5% oxygen on recovery. The source of concentrated oxygen was O-PUR (Oxyfit. Research subjects completed two thirty-second Wingate tests at an interval of ten minutes, and in the interval between the tests the subjects inhaled either oxygen or a placebo in random order. This procedure was then repeated. The pilot study revealed a significantly (p<0.03 smaller performance drop in the second Wingate test following the inhalation of 99.5% oxygen when compared with the placebo. The results of the study indicate that inhaling concentrated oxygen may have a positive effect on short-term recovery processes.

Reduction of oxygen concentration by heater design during Czochralski Si growth

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Zhou, Bing; Chen, Wenliang; Li, Zhihui; Yue, Ruicun; Liu, Guowei; Huang, Xinming

2018-02-01

Oxygen is one of the highest-concentration impurities in single crystals grown by the Czochralski (CZ) process, and seriously impairs the quality of the Si wafer. In this study, computer simulations were applied to design a new CZ system. A more appropriate thermal field was acquired by optimization of the heater structure. The simulation results showed that, compared with the conventional system, the oxygen concentration in the newly designed CZ system was reduced significantly throughout the entire CZ process because of the lower crucible wall temperature and optimized convection. To verify the simulation results, experiments were conducted on an industrial single-crystal furnace. The experimental results showed that the oxygen concentration was reduced significantly, especially at the top of the CZ-Si ingot. Specifically, the oxygen concentration was 6.19 × 1017 atom/cm3 at the top of the CZ-Si ingot with the newly designed CZ system, compared with 9.22 × 1017 atom/cm3 with the conventional system. Corresponding light-induced degradation of solar cells based on the top of crystals from the newly designed CZ system was 1.62%, a reduction of 0.64% compared with crystals from the conventional system (2.26%).

Numerical simulation of the oxygen concentration distribution in silicon melt for different crystal lengths during Czochralski growth with a transverse magnetic field

Science.gov (United States)

Chen, Jyh-Chen; Chiang, Pei-Yi; Nguyen, Thi Hoai Thu; Hu, Chieh; Chen, Chun-Hung; Liu, Chien-Cheng

2016-10-01

A three-dimensional simulation model is used to study the oxygen concentration distribution in silicon crystal during the Czochralski growth process under a transverse uniform magnetic field. The flow, temperature, and oxygen concentration distributions inside the furnace are calculated for different crystal lengths. There is significant variation in the flow structure in the melt with the growth length. The results show that in the initial stages, there is a decrease in the oxygen concentration at the crystal-melt interface as the length of the growing crystal increases. As the crystal lengthens further, a minimum value is reached after which the oxygen concentration increases continuously. This trend is consistent with that shown in the experimental results. The variation of the oxygen concentration with the growth length is strongly related to the depth of the melt in the crucible and the flow structure inside the melt. Better uniformity of the axial oxygen concentration can be achieved by proper adjustment of the crucible rotation rate during the growth process.

One year of Seaglider dissolved oxygen concentration profiles at the PAP site

Science.gov (United States)

Binetti, Umberto; Kaiser, Jan; Heywood, Karen; Damerell, Gillian; Rumyantseva, Anna

2015-04-01

Oxygen is one of the most important variables measured in oceanography, influenced both by physical and biological factors. During the OSMOSIS project, 7 Seagliders were used in 3 subsequent missions to measure a multidisciplinary suite of parameters at high frequency in the top 1000 m of the water column for one year, from September 2012 to September 2013. The gliders were deployed at the PAP time series station (nominally at 49° N 16.5° W) and surveyed the area following a butterfly-shaped path. Oxygen concentration was measured by Aanderaa optodes and calibrated using ship CTD O2 profiles during 5 deployment and recovery cruises, which were in turn calibrated by Winkler titration of discrete samples. The oxygen-rich mixed layer deepens in fall and winter and gets richer in oxygen when the temperature decreases. The spring bloom did not happen as expected, but instead the presence of a series of small blooms was measured throughout spring and early summer. During the summer the mixed layer become very shallow and oxygen concentrations decreased. A Deep Oxygen Maximum (DOM) developed along with a deep chlorophyll maximum during the summer and was located just below the mixed layer . At this depth, phytoplankton had favourable light and nutrient conditions to grow and produce oxygen, which was not subject to immediate outgassing. The oxygen concentration in the DOM was not constant, but decreased, then increased again until the end of the mission. Intrusions of oxygen rich water are also visible throughout the mission. These are probably due to mesoscale events through the horizontal transport of oxygen and/or nutrients that can enhance productivity, particularly at the edge of the fronts. We calculate net community production (NCP) by analysing the variation in oxygen with time. Two methods have been proposed. The classical oxygen budget method assumes that changes in oxygen are due to the sum of air-sea flux, isopycnal advection, diapycnal mixing and NCP. ERA

Radiosensitivity of Hela cells in various O2 concentrations and consideration of oxygen effect in radiotherapy

International Nuclear Information System (INIS)

Kuroda, Yoshikazu; Nyunoya, Koichiro

1979-01-01

The aim of this paper is the study of the radiosensitivity of HeLa cells in vitro in various oxygen concentrations and the consideration of the utilization of oxygen effect in radiation therapy, based on the data of HeLa cells and tumor oxygen tension. Survival curves of HeLa cells are found to be exponential as a function of radiation dose and the radiosensitivity is dependent on oxygen tension of culture medium. Relative radiosensitivity decreases remarkably at low level of oxygen, especially under 9 mmHg pO 2 . The utilization of oxygen effect in radiation may be useful in hyperbaric oxygen inhalation and not useful under local tissue hypoxia induced by tourniquet application. Reoxygenation occurs with shrinkage of tumor after irradiation and this phenomenon will diminish the value of hyperbaric oxygen in radiation therapy. (author)

Relating oxygen partial pressure, saturation and content: the haemoglobin-oxygen dissociation curve.

Science.gov (United States)

Collins, Julie-Ann; Rudenski, Aram; Gibson, John; Howard, Luke; O'Driscoll, Ronan

2015-09-01

The delivery of oxygen by arterial blood to the tissues of the body has a number of critical determinants including blood oxygen concentration (content), saturation (S O2 ) and partial pressure, haemoglobin concentration and cardiac output, including its distribution. The haemoglobin-oxygen dissociation curve, a graphical representation of the relationship between oxygen satur-ation and oxygen partial pressure helps us to understand some of the principles underpinning this process. Historically this curve was derived from very limited data based on blood samples from small numbers of healthy subjects which were manipulated in vitro and ultimately determined by equations such as those described by Severinghaus in 1979. In a study of 3524 clinical specimens, we found that this equation estimated the S O2 in blood from patients with normal pH and S O2 >70% with remarkable accuracy and, to our knowledge, this is the first large-scale validation of this equation using clinical samples. Oxygen saturation by pulse oximetry (S pO2 ) is nowadays the standard clinical method for assessing arterial oxygen saturation, providing a convenient, pain-free means of continuously assessing oxygenation, provided the interpreting clinician is aware of important limitations. The use of pulse oximetry reduces the need for arterial blood gas analysis (S aO2 ) as many patients who are not at risk of hypercapnic respiratory failure or metabolic acidosis and have acceptable S pO2 do not necessarily require blood gas analysis. While arterial sampling remains the gold-standard method of assessing ventilation and oxygenation, in those patients in whom blood gas analysis is indicated, arterialised capillary samples also have a valuable role in patient care. The clinical role of venous blood gases however remains less well defined.

Relating oxygen partial pressure, saturation and content: the haemoglobin–oxygen dissociation curve

Directory of Open Access Journals (Sweden)

Julie-Ann Collins

2015-09-01

The delivery of oxygen by arterial blood to the tissues of the body has a number of critical determinants including blood oxygen concentration (content, saturation (SO2 and partial pressure, haemoglobin concentration and cardiac output, including its distribution. The haemoglobin–oxygen dissociation curve, a graphical representation of the relationship between oxygen satur­ation and oxygen partial pressure helps us to understand some of the principles underpinning this process. Historically this curve was derived from very limited data based on blood samples from small numbers of healthy subjects which were manipulated in vitro and ultimately determined by equations such as those described by Severinghaus in 1979. In a study of 3524 clinical specimens, we found that this equation estimated the SO2 in blood from patients with normal pH and SO2 >70% with remarkable accuracy and, to our knowledge, this is the first large-scale validation of this equation using clinical samples. Oxygen saturation by pulse oximetry (SpO2 is nowadays the standard clinical method for assessing arterial oxygen saturation, providing a convenient, pain-free means of continuously assessing oxygenation, provided the interpreting clinician is aware of important limitations. The use of pulse oximetry reduces the need for arterial blood gas analysis (SaO2 as many patients who are not at risk of hypercapnic respiratory failure or metabolic acidosis and have acceptable SpO2 do not necessarily require blood gas analysis. While arterial sampling remains the gold-standard method of assessing ventilation and oxygenation, in those patients in whom blood gas analysis is indicated, arterialised capillary samples also have a valuable role in patient care. The clinical role of venous blood gases however remains less well defined.

Microfabricated Collector-Generator Electrode Sensor for Measuring Absolute pH and Oxygen Concentrations.

Science.gov (United States)

Dengler, Adam K; Wightman, R Mark; McCarty, Gregory S

2015-10-20

Fast-scan cyclic voltammetry (FSCV) has attracted attention for studying in vivo neurotransmission due to its subsecond temporal resolution, selectivity, and sensitivity. Traditional FSCV measurements use background subtraction to isolate changes in the local electrochemical environment, providing detailed information on fluctuations in the concentration of electroactive species. This background subtraction removes information about constant or slowly changing concentrations. However, determination of background concentrations is still important for understanding functioning brain tissue. For example, neural activity is known to consume oxygen and produce carbon dioxide which affects local levels of oxygen and pH. Here, we present a microfabricated microelectrode array which uses FSCV to detect the absolute levels of oxygen and pH in vitro. The sensor is a collector-generator electrode array with carbon microelectrodes spaced 5 μm apart. In this work, a periodic potential step is applied at the generator producing transient local changes in the electrochemical environment. The collector electrode continuously performs FSCV enabling these induced changes in concentration to be recorded with the sensitivity and selectivity of FSCV. A negative potential step applied at the generator produces a transient local pH shift at the collector. The generator-induced pH signal is detected using FSCV at the collector and correlated to absolute solution pH by postcalibration of the anodic peak position. In addition, in oxygenated solutions a negative potential step at the generator produces hydrogen peroxide by reducing oxygen. Hydrogen peroxide is detected with FSCV at the collector electrode, and the magnitude of the oxidative peak is proportional to absolute oxygen concentrations. Oxygen interference on the pH signal is minimal and can be accounted for with a postcalibration.

A theoretical evaluation of the oxygen concentration in a corrosion-fatigue crack

International Nuclear Information System (INIS)

Turnbull, A.

1981-01-01

The oxygen concentration in a corrosion-fatigue crack has been evaluated theoretically by assuming that oxygen was consumed by cathodic reduction on the walls of the crack and mass transport occurred by diffusion and advection (forced convection), with the latter resulting from the sinusoidal variation of the displacement of the crack walls. By using parameters relevant to a compact tension specimen, the time-dependent distribution of the oxygen concentration in the crack was calculated as a function of ΔK (the range of the stress intensity factor), R-value (minimum load/maximum load), frequency, crack length, and electrode potential. The influence of advection was to significantly enhance the mass transport of oxygen in the crack compared with ''diffusion-only'' even at low frequencies and low ΔK. Regions in the crack were identified in which advection dominance or diffusion dominance of the mass transport of oxygen occurred

Spectral filtering modulation method for estimation of hemoglobin concentration and oxygenation based on a single fluorescence emission spectrum in tissue phantoms.

Science.gov (United States)

Liu, Quan; Vo-Dinh, Tuan

2009-10-01

Hemoglobin concentration and oxygenation in tissue are important biomarkers that are useful in both research and clinical diagnostics of a wide variety of diseases such as cancer. The authors aim to develop simple ratiometric method based on the spectral filtering modulation (SFM) of fluorescence spectra to estimate the total hemoglobin concentration and oxygenation in tissue using only a single fluorescence emission spectrum, which will eliminate the need of diffuse reflectance measurements and prolonged data processing as required by most current methods, thus enabling rapid clinical measurements. The proposed method consists of two steps. In the first step, the total hemoglobin concentration is determined by comparing a ratio of fluorescence intensities at two emission wavelengths to a calibration curve. The second step is to estimate oxygen saturation by comparing a double ratio that involves three emission wavelengths to another calibration curve that is a function of oxygen saturation for known total hemoglobin concentration. Theoretical derivation shows that the ratio in the first step is linearly proportional to the total hemoglobin concentrations and the double ratio in the second step is related to both total hemoglobin concentration and hemoglobin oxygenation for the chosen fiber-optic probe geometry. Experiments on synthetic fluorescent tissue phantoms, which included hemoglobin with both constant and varying oxygenation as the absorber, polystyrene spheres as scatterers, and flavin adenine dinucleotide as the fluorophore, were carried out to validate the theoretical prediction. Tissue phantom experiments confirm that the ratio in the first step is linearly proportional to the total hemoglobin concentration and the double ratio in the second step is related to both total hemoglobin concentrations and hemoglobin oxygenation. Furthermore, the relations between the two ratios and the total hemoglobin concentration and hemoglobin oxygenation are insensitive

Bulk manufacture of concentrated oxygen gas-filled microparticles for intravenous oxygen delivery.

Science.gov (United States)

Kheir, John N; Polizzotti, Brian D; Thomson, Lindsay M; O'Connell, Daniel W; Black, Katherine J; Lee, Robert W; Wilking, James N; Graham, Adam C; Bell, David C; McGowan, Francis X

2013-08-01

Self-assembling, concentrated, lipid-based oxygen microparticles (LOMs) have been developed to administer oxygen gas when injected intravenously, preventing organ injury and death from systemic hypoxemia in animal models. Distinct from blood substitutes, LOMs are a one-way oxygen carrier designed to rescue patients who experience life-threatening hypoxemia, as caused by airway obstruction or severe lung injury. Here, we describe methods to manufacture large quantities of LOMs using an in-line, recycling, high-shear homogenizer, which can create up to 4 liters of microparticle emulsion in 10 minutes, with particles containing a median diameter of 0.93 microns and 60 volume% of gas phase. Using this process, we screen 30 combinations of commonly used excipients for their ability to form stable LOMs. LOMs composed of DSPC and cholesterol in a 1:1 molar ratio are stable for a 100 day observation period, and the number of particles exceeding 10 microns in diameter does not increase over time. When mixed with blood in vitro, LOMs fully oxygenate blood within 3.95 seconds of contact, and do not cause hemolysis or complement activation. LOMs can be manufactured in bulk by high shear homogenization, and appear to have a stability and size profile which merit further testing. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

CERN Document Server

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...

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

International Nuclear Information System (INIS)

Murin, L.I.; Lindstroem, J.L.; Misiuk, A.

2003-01-01

Local vibrational mode (LVM) spectroscopy is used to explore the effect of high hydrostatic pressure (HP) on the formation of small oxygen-related clusters (dimers, trimers, thermal donors, and C-O complexes) at 450 deg. C and 650 deg. C in Cz-Si crystals with different impurity content and prehistory. It is found, in agreement with previous studies, that HP enhances the oxygen clustering in Cz-Si at elevated temperatures. The effect of HP is related mainly to enhancement in the diffusivity of single oxygen atoms and small oxygen aggregates. HP does not noticeably increase the binding energies of the most simple oxygen related complexes like O 2i , C s O ni . The biggest HP effect on the thermal double donor (TDDs) generation is revealed in hydrogenated samples. Heat-treatment of such samples at 450 deg. C under HP results in extremely high TDD introduction rates as well as in a strong increase in the concentration of the first TDD species

Influence of variable oxygen concentration on the response of cells to heat or x irradiation

International Nuclear Information System (INIS)

Gerweck, L.E.; Richards, B.; Jennings, M.

1981-01-01

The influence of oxygen concentration on the lethal response of cells exposed to 43 0 C hyperthermia was determined and compared to the response of cells exposed to radiation under equivalent culturing and environmental conditions. Chinese hamster ovary (CHO) cells were heated or irradiated 0.5 h after induction of hypoxia and then reoxygenated following treatment. The oxygen enhancement ratio (OER) for heat or radiation was determined at the 1% survival level from least-squares fit of survival curves. A maximum OER of 3.1 +- 0.2 was observed in the 20 to 95% oxygen concentration range. The OER for heat, however, was 1.0 +- 0.1 irrespective of the gas-phase oxygen concentration. These results show that the lethal effects of heat are not influenced by the oxygen concentration at the time of treatment in CHO cells exposed to 43 0 C hyperthermia

Automatic measuring device for atomic oxygen concentrations (1962); Dispositif de mesure automatique de concentrations d'oxygene atomique (1962)

Energy Technology Data Exchange (ETDEWEB)

Weill, J; Deiss, M; Mercier, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1962-07-01

Within the framework of the activities of the Autonomous Reactor Electronics Section we have developed a device, which renders automatic one type of measurement carried out in the Physical Chemistry Department at the Saclay Research Centre. We define here: - the physico-chemical principle of the apparatus which is adapted to the measurement of atomic oxygen concentrations; - the physical principle of the automatic measurement; - the properties, performance, constitution, use and maintenance of the automatic measurement device. It is concluded that the principle of the automatic device, whose tests have confirmed the estimation of the theoretical performance, could usefully be adapted to other types of measurement. (authors) [French] Dans le cadre des activites de la Section Autonome d'Electronique des Reacteurs, il a ete realise et mis au point un dispositif permettant de rendre automatique un type de mesures effectuees au Departement de Physico-Chimie du C.E.N. SACLAY. On definit ici: - le principe physico-chimique de l'appareillage, adapte a la mesure de concentrations de l'oxygene atomique; - le principe physique de la mesure automatique; - les qualites, performances, constitution, utilisation, et maintenance du dispositif de mesure automatique. Il est porte en conclusion, que le principe du dispositif automatique realise, dont les essais ont sensiblement confirme l'evaluation des performances theoriques, pourrait etre utilement adapte a d'autres types de mesures courantes. (auteurs)

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

Science.gov (United States)

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.

Testing the fidelity of laminations as a proxy for oxygen concentration in the Bering Sea over millennial to orbital timescales

Science.gov (United States)

Black, A. E.; Baranow, N.; Amdur, S.; Cook, M. S.

2017-12-01

Ocean circulation and biological productivity play an important role in the climate system through their contribution to global heat transport and air-sea exchange of CO­2. Oceanic oxygen concentration provides insight to ocean circulation and biological productivity. Sediment laminations provide a valuable proxy for local oceanic oxygen concentration. Many sediment cores from the Pacific Ocean are laminated from the last deglaciation, but previous studies have not provided an in-depth examination of laminations over many glacial and interglacial (G/IG) cycles. Typically, studies to date that consider bioturbation as a proxy for oxygen concentration have only considered one sediment core from a site, leaving ambiguity as to whether laminations faithfully record local oxygen levels. With sediment cores from three different holes (A, C, D) on the northern Bering Slope from IODP site U1345 (1008m), we investigate how faithfully laminations record oxygen concentration. We assign a bioturbation index from 1 to 4 for 1-cm intervals for the cores from each of the three holes and align the holes based on physical properties data. We find that the bioturbation is relatively consistent (within one bioturbation unit) between holes, suggesting that laminations may be a faithful, if not perfect, proxy for local oxygen concentration. After examining laminations from a complete hole, representing over 500,000 years, there seems to be no consistent pattern of laminations during the past five glacial cycles, suggesting there is no consistent pattern to oxygen concentration during glacial periods in the northern Bering Slope. Thus, hypotheses on ocean circulation and productivity in the northern Bering Sea from the last deglaciation may not apply to previous G/IG cycles.

Process design and simulation for optimizing the oxygen concentration in Czochralski-grown single-crystal silicon

International Nuclear Information System (INIS)

Jung, Y. J.; Kim, W. K.; Jung, J. H.

2014-01-01

The highest-concentration impurity in a single-crystal silicon ingot is oxygen, which infiltrates the ingot during growth stage. This oxygen adversely affects the wafer is quality. This study was aimed at finding an optimal design for the Czochralski (Cz) process to enable high-quality and low cost (by reducing power consumption) wafer production by controlling the oxygen concentration in the silicon ingots. In the Cz process, the characteristics of silicon ingots during crystallization are greatly influenced by the design and the configuration of the hot zone, and by crystallization rate. In order to identify process conditions for obtaining an optimal oxygen concentration of 11 - 13 ppma (required for industrial-grade ingots), designed two shield shapes for the hot zone. Furthermore, oxygen concentrations corresponding to these two shapes were compared by evaluating each shape at five different production speeds. In addition, simulations were performed to identify the optimal shield design for industrial applications.

Process design and simulation for optimizing the oxygen concentration in Czochralski-grown single-crystal silicon

Energy Technology Data Exchange (ETDEWEB)

Jung, Y. J.; Kim, W. K.; Jung, J. H. [Yeungnam University, Gyeongsan (Korea, Republic of)

2014-08-15

The highest-concentration impurity in a single-crystal silicon ingot is oxygen, which infiltrates the ingot during growth stage. This oxygen adversely affects the wafer is quality. This study was aimed at finding an optimal design for the Czochralski (Cz) process to enable high-quality and low cost (by reducing power consumption) wafer production by controlling the oxygen concentration in the silicon ingots. In the Cz process, the characteristics of silicon ingots during crystallization are greatly influenced by the design and the configuration of the hot zone, and by crystallization rate. In order to identify process conditions for obtaining an optimal oxygen concentration of 11 - 13 ppma (required for industrial-grade ingots), designed two shield shapes for the hot zone. Furthermore, oxygen concentrations corresponding to these two shapes were compared by evaluating each shape at five different production speeds. In addition, simulations were performed to identify the optimal shield design for industrial applications.

Effect of Mechanical Alloying Atmospheres and Oxygen Concentration on Mechanical Properties of ODS Ferritic Steels

International Nuclear Information System (INIS)

Noh, Sanghoon; Choi, Byoungkwon; Han, Changhee; Kim, Kibaik; Kang, Sukhoon; Chun, Youngbum; Kim, Taekyu

2013-01-01

Finely dispersed nano-oxide particles with a high number density in the homogeneous grain matrix are essential to achieve superior mechanical properties at high temperatures, and these unique microstructures can be obtained through the mechanical alloying (MA) and hot consolidation process. The microstructure and mechanical property of ODS steel significantly depends on its powder property and the purity after the MA process. These contents should be carefully controlled to improve the mechanical property at elevated temperature. In particular, appropriate the control of oxygen concentration improves the mechanical property of ODS steel at high temperature. An effective method is to control the mechanical alloying atmosphere by high purity inert gas. In the present study, the effects of mechanical alloying atmospheres and oxygen concentration on the mechanical property of ODS steel were investigated. ODS ferritic alloys were fabricated in various atmospheres, and the HIP process was used to investigate the effects of MA atmospheres and oxygen concentration on the microstructure and mechanical property. ODS ferritic alloys milled in an Ar-H 2 mixture, and He is effective to reduce the excess oxygen concentration. The YH 2 addition made an extremely reduced oxygen concentration by the internal oxygen reduction reaction and resulted in a homogeneous microstructure and superior creep strength

Effects of ambient oxygen concentration on biodiesel and diesel spray combustion under simulated engine conditions

KAUST Repository

Zhang, Ji

2013-08-01

This study investigates the effect of ambient oxygen concentration on biodiesel and diesel spray combustion under simulated compression-ignition engine conditions in a constant-volume chamber. The apparent heat release rate (AHRR) is calculated based on the measured pressure. High-speed imaging of OH* chemiluminescence and natural luminosity (NL) is employed to visualize the combustion process. Temporally and spatially resolved NL and OH* contour plots are obtained. The result indicates that AHRR depends monotonically on the ambient oxygen concentration for both fuels. A lower oxygen concentration yields a slower AHRR increase rate, a lower peak AHRR value, but a higher AHRR value during the burn-out stage when compared with higher ambient oxygen concentration conditions. OH* chemiluminescence and NL contours indicate that biodiesel may experience a longer premixed-combustion duration. The 18% ambient O2 condition works better for biodiesel than diesel in reducing soot luminosity. With 12% O2, diesel combustion is significantly degraded. However, both fuels experience low temperature combustion at 10% O2. These results may imply that biodiesel is able to achieve the desired lower soot production under a moderate oxygen level with higher combustion efficiency, while diesel needs to be burned under very low ambient oxygen concentration for low soot production. © 2013 Elsevier Ltd.

Effects of ambient oxygen concentration on biodiesel and diesel spray combustion under simulated engine conditions

KAUST Repository

Zhang, Ji; Jing, Wei; Roberts, William L.; Fang, Tiegang

2013-01-01

This study investigates the effect of ambient oxygen concentration on biodiesel and diesel spray combustion under simulated compression-ignition engine conditions in a constant-volume chamber. The apparent heat release rate (AHRR) is calculated based on the measured pressure. High-speed imaging of OH* chemiluminescence and natural luminosity (NL) is employed to visualize the combustion process. Temporally and spatially resolved NL and OH* contour plots are obtained. The result indicates that AHRR depends monotonically on the ambient oxygen concentration for both fuels. A lower oxygen concentration yields a slower AHRR increase rate, a lower peak AHRR value, but a higher AHRR value during the burn-out stage when compared with higher ambient oxygen concentration conditions. OH* chemiluminescence and NL contours indicate that biodiesel may experience a longer premixed-combustion duration. The 18% ambient O2 condition works better for biodiesel than diesel in reducing soot luminosity. With 12% O2, diesel combustion is significantly degraded. However, both fuels experience low temperature combustion at 10% O2. These results may imply that biodiesel is able to achieve the desired lower soot production under a moderate oxygen level with higher combustion efficiency, while diesel needs to be burned under very low ambient oxygen concentration for low soot production. © 2013 Elsevier Ltd.

Effect of hyperbaric oxygen therapy combined with autologous platelet concentrate applied in rabbit fibula fraction healing

Directory of Open Access Journals (Sweden)

Paulo Cesar Fagundes Neves

2013-09-01

Full Text Available OBJECTIVES: The purpose is to study the effects of hyperbaric oxygen therapy and autologous platelet concentrates in healing the fibula bone of rabbits after induced fractures. METHODS: A total of 128 male New Zealand albino rabbits, between 6-8 months old, were subjected to a total osteotomy of the proximal portion of the right fibula. After surgery, the animals were divided into four groups (n = 32 each: control group, in which animals were subjected to osteotomy; autologous platelet concentrate group, in which animals were subjected to osteotomy and autologous platelet concentrate applied at the fracture site; hyperbaric oxygen group, in which animals were subjected to osteotomy and 9 consecutive daily hyperbaric oxygen therapy sessions; and autologous platelet concentrate and hyperbaric oxygen group, in which animals were subjected to osteotomy, autologous platelet concentrate applied at the fracture site, and 9 consecutive daily hyperbaric oxygen therapy sessions. Each group was divided into 4 subgroups according to a pre-determined euthanasia time points: 2, 4, 6, and 8 weeks postoperative. After euthanasia at a specific time point, the fibula containing the osseous callus was prepared histologically and stained with hematoxylin and eosin or picrosirius red. RESULTS: Autologous platelet concentrates and hyperbaric oxygen therapy, applied together or separately, increased the rate of bone healing compared with the control group. CONCLUSION: Hyperbaric oxygen therapy and autologous platelet concentrate combined increased the rate of bone healing in this experimental model.

Effects of vacuum suctioning and strategic drape tenting on oxygen concentration in a simulated surgical field.

Science.gov (United States)

Kung, Theodore A; Kong, Sarah W; Aliu, Oluseyi; Azizi, Jahan; Kai, Salim; Cederna, Paul S

2016-02-01

To investigate the isolated and combined effects of vacuum suctioning and strategic drape tenting on oxygen concentration in an experimental setting. Experimental. Clinical simulation center of a university-affiliated hospital. Mannequin simulation of a patient undergoing facial surgery under sedation anesthesia. Supplemental oxygen was delivered via nasal cannula. Vacuum suctioning and strategic drape tenting. The experimental trials entailed measuring oxygen concentration around the nasal cannula continuously either in the presence or absence of a standard operating room vacuum suction system and strategic tenting of surgical drapes. The primary outcome was the time required for oxygen concentration to reach 21%. In the control group (without suction or strategic tenting), a mean time of 180 seconds elapsed until the measured oxygen concentration reached 21% after cessation of oxygen delivery. Use of a vacuum suction device alone (110 seconds; P strategic tenting (110 seconds; P strategic tenting of surgical drapes has a theoretical benefit to decreasing the pooling of oxygen around the surgical site, further investigation is necessary before its routine use is recommended. Copyright © 2016 Elsevier Inc. All rights reserved.

Dissolved oxygen concentration in the medium during cell culture: Defects and improvements.

Science.gov (United States)

Zhang, Kuan; Zhao, Tong; Huang, Xin; He, Yunlin; Zhou, Yanzhao; Wu, Liying; Wu, Kuiwu; Fan, Ming; Zhu, Lingling

2016-03-01

In vitro cell culture has provided a useful model to study the effects of oxygen on cellular behavior. However, it remains unknown whether the in vitro operations themselves affect the medium oxygen levels and the living states of cells. In addition, a prevailing controversy is whether reactive oxygen species (ROS) production is induced by continuous hypoxia or reoxygenation. In this study, we have measured the effects of different types of cell culture containers and the oxygen environment where medium replacement takes place on the actual oxygen tension in the medium. We found that the deviations of oxygen concentrations in the medium are much greater in 25-cm(2) flasks than in 24-well plates and 35-mm dishes. The dissolved oxygen concentrations in the medium were increased after medium replacement in normoxia, but remained unchanged in glove boxes in which the oxygen tension remained at a low level (11.4, 5.7, and 0.5% O2 ). We also found that medium replacement in normoxia increased the number of ROS-positive cells and reduced the cell viability; meanwhile, medium replacement in a glove box did not produce the above effects. Therefore, we conclude that the use of 25-cm(2) flasks should be avoided and demonstrate that continuous hypoxia does not produce ROS, whereas the reoxygenation that occurs during the harvesting of cells leads to ROS and induces cell death. © 2015 International Federation for Cell Biology.

Detection of ultra-low oxygen concentration based on the fluorescence blinking dynamics of single molecules

Science.gov (United States)

Wu, Ruixiang; Chen, Ruiyun; Zhou, Haitao; Qin, Yaqiang; Zhang, Guofeng; Qin, Chengbing; Gao, Yan; Gao, Yajun; Xiao, Liantuan; Jia, Suotang

2018-01-01

We present a sensitive method for detection of ultra-low oxygen concentrations based on the fluorescence blinking dynamics of single molecules. The relationship between the oxygen concentration and the fraction of time spent in the off-state, stemming from the population and depopulation of triplet states and radical cationic states, can be fitted with a two-site quenching model in the Stern-Volmer plot. The oxygen sensitivity is up to 43.42 kPa-1 in the oxygen partial pressure region as low as 0.01-0.25 kPa, which is seven times higher than that of the fluorescence intensity indicator. This method avoids the limitation of the sharp and non-ignorable fluctuations that occur during the measurement of fluorescence intensity, providing potential applications in the field of low oxygen-concentration monitoring in life science and industry.

Short-term molecular acclimation processes of legume nodules to increased external oxygen concentration

Directory of Open Access Journals (Sweden)

Ulrike eAvenhaus

2016-01-01

Full Text Available Nitrogenase is an oxygen labile enzyme. Microaerobic conditions within the infected zone of nodules are maintained primarily by an oxygen diffusion barrier located in the nodule cortex. Flexibility of the oxygen diffusion barrier is important for the acclimation processes of nodules in response to changes in external oxygen concentration. The hypothesis of the present study was that there are additional molecular mechanisms involved. Nodule activity of Medicago truncatula plants were continuously monitored during a change from 21 to 25 or 30 % oxygen around root nodules by measuring nodule H2 evolution. Within about two minutes of the increase in oxygen concentration, a steep decline in nitrogenase activity occurred. A quick recovery commenced about eight minutes later. A qPCR-based analysis of the expression of genes for nitrogenase components showed a tendency towards upregulation during the recovery. The recovery resulted in a new constant activity after about 30 minutes, corresponding to approximately 90 % of the pre-treatment level. An RNAseq-based comparative transcriptome profiling of nodules at that point in time revealed that genes for nodule-specific cysteine-rich (NCR peptides, defensins, leghaemoglobin and chalcone and stilbene synthase were significantly upregulated when considered as a gene family. A gene for a nicotianamine synthase-like protein (Medtr1g084050 showed a strong increase in count number. The gene appears to be of importance for nodule functioning, as evidenced by its consistently high expression in nodules and a strong reaction to various environmental cues that influence nodule activity. A Tnt1-mutant that carries an insert in the coding sequence (cds of that gene showed reduced nitrogen fixation and less efficient acclimation to an increased external oxygen concentration. It was concluded that sudden increases in oxygen concentration around nodules destroy nitrogenase, which is quickly counteracted by an increased

Evaluation of dissolved oxygen and organic substances concentrations in water of the nature reserve Alluvium Zitavy

International Nuclear Information System (INIS)

Palaticka, A.; Noskovic, J.; Babosova, M.

2007-01-01

In 2006 concentrations of dissolved oxygen and organic substances were evaluated in water in the Nature Reserve Alluvium Zitavy (indirect method based on their oxidation by K 2 Cr 2 0 7 was used). The results are represented in mg of O 2 · dm -3 . Taking of samples took place in 6 sampling sites in regular month intervals. Based on obtained data and according to the standard STN 75 7221 (Water quality -The classification of the water surface quality) water in individual sampling sites was ranked into the classes of the .water surface quality. From the data it is clear that the concentrations of dissolved oxygen and organic substances in the Nature Reserve Alluvium Zitavy changed in dependence on sampling sites and time. The highest mean concentrations of dissolved oxygen in dependence on sampling time were found out in spring months and the lowest concentrations in summer months. They ranged from 1.6 mg 0 2 · dm -3 (July) to 9.0 mg O 2 · dm -3 (March). Falling dissolved oxygen values can be related to successive increase of water temperature, thus good conditions were created for decomposition of organic matter by microorganisms in water and sediments in which they use dissolved oxygen. In dependence on sampling place the highest mean concentration of dissolved oxygen was in sampling site No. 4 (6.0 mg 0 2 · dm -3 ) which is situated in the narrowest place in the NR. The lowest value was in sampling site No. 2 (3.6 mg 0 2 · dm -3 ) which is a typical wetland ecosystem. High mean values of COD Cr in dependence on sampling time were determined in summer months and low values during winter moths. Dependence of COD Cr values on sampling site was also manifested. The lowest mean value was obtained in sampling site No. 4 (59.5 mg · dm -3 ) and the highest value in sampling site No. 5 (97.1 mg · dm -3 ) which is also a typical wetland. Based on the results and according to the STN 75 7221 we ranked water in all sampling sites into the 5 th class of the water

Mapping oxygen concentration in the awake mouse brain

Science.gov (United States)

Lyons, Declan G; Parpaleix, Alexandre; Roche, Morgane; Charpak, Serge

2016-01-01

Although critical for brain function, the physiological values of cerebral oxygen concentration have remained elusive because high-resolution measurements have only been performed during anesthesia, which affects two major parameters modulating tissue oxygenation: neuronal activity and blood flow. Using measurements of capillary erythrocyte-associated transients, fluctuations of oxygen partial pressure (Po2) associated with individual erythrocytes, to infer Po2 in the nearby neuropil, we report the first non-invasive micron-scale mapping of cerebral Po2 in awake, resting mice. Interstitial Po2 has similar values in the olfactory bulb glomerular layer and the somatosensory cortex, whereas there are large capillary hematocrit and erythrocyte flux differences. Awake tissue Po2 is about half that under isoflurane anesthesia, and within the cortex, vascular and interstitial Po2 values display layer-specific differences which dramatically contrast with those recorded under anesthesia. Our findings emphasize the importance of measuring energy parameters non-invasively in physiological conditions to precisely quantify and model brain metabolism. DOI: http://dx.doi.org/10.7554/eLife.12024.001 PMID:26836304

The dynamics of dissolved oxygen concentration for water quality monitoring and assessment in polder ditches

NARCIS (Netherlands)

Veeningen, R.

1983-01-01

This study deals with the use of the dynamics of dissolved oxygen concentration for water quality assessment in polder ditches. The dynamics of the dissolved oxygen concentration, i.e. the temporal and spatial variations in a few polder ditches under a range of natural, pollution and management

Deep vs shallow nature of oxygen vacancies and consequent n -type carrier concentrations in transparent conducting oxides

Science.gov (United States)

Buckeridge, J.; Catlow, C. R. A.; Farrow, M. R.; Logsdail, A. J.; Scanlon, D. O.; Keal, T. W.; Sherwood, P.; Woodley, S. M.; Sokol, A. A.; Walsh, A.

2018-05-01

The source of n -type conductivity in undoped transparent conducting oxides has been a topic of debate for several decades. The point defect of most interest in this respect is the oxygen vacancy, but there are many conflicting reports on the shallow versus deep nature of its related electronic states. Here, using a hybrid quantum mechanical/molecular mechanical embedded cluster approach, we have computed formation and ionization energies of oxygen vacancies in three representative transparent conducting oxides: In2O3 ,SnO2, and ZnO. We find that, in all three systems, oxygen vacancies form well-localized, compact donors. We demonstrate, however, that such compactness does not preclude the possibility of these states being shallow in nature, by considering the energetic balance between the vacancy binding electrons that are in localized orbitals or in effective-mass-like diffuse orbitals. Our results show that, thermodynamically, oxygen vacancies in bulk In2O3 introduce states above the conduction band minimum that contribute significantly to the observed conductivity properties of undoped samples. For ZnO and SnO2, the states are deep, and our calculated ionization energies agree well with thermochemical and optical experiments. Our computed equilibrium defect and carrier concentrations, however, demonstrate that these deep states may nevertheless lead to significant intrinsic n -type conductivity under reducing conditions at elevated temperatures. Our study indicates the importance of oxygen vacancies in relation to intrinsic carrier concentrations not only in In2O3 , but also in SnO2 and ZnO.

The role of changes in the oxygen concentration in modification of reproductive death of cells in vitro

International Nuclear Information System (INIS)

Korystov, Yu.N.

1983-01-01

In this report the data are discussed and summarized concerning cell oxygenation in culture. Formulae are proposed for calculation of the oxygen concentration in suspension, monolayer and spheroid, as well as numerical parameters are submitted determining the oxygenation of cells in vitro. This permits to estimate quantitatively the oxygen concentration at the cell surface upon irradiation in different experimental conditions

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

International Nuclear Information System (INIS)

Moll, M.; Fretwurst, E.; Lindstroem, G.

2000-01-01

We present an investigation on the influence of the oxygen concentration on radiation-induced changes in the effective doping concentration of silicon detectors. Diodes fabricated from silicon with interstitial oxygen content ranging from below 2x10 14 to 9x10 17 cm -3 have been irradiated with fast neutrons up to a fluence of 2x10 15 cm -2 . Our main interest focused on the so-called stable damage component in the change of the effective doping concentration being of prime importance for the application of silicon detectors in high-energy physics experiments. We demonstrate, that with a high oxygen enrichment the donor removal is appreciably reduced, reaching a value of only 10% of the initial doping concentration for [O i ]=9x10 17 cm -3 , while for normal detector grade material with [O i ] below 5x10 16 cm -3 that value is 60-90%. Furthermore, we show that the fluence proportional introduction of stable acceptors is independent of the oxygen concentration with an averaged introduction rate of (1.49±0.03)x10 -2 cm -1 . Only one material was found exhibiting a significantly smaller value of about 0.6x10 -2 cm -1 and thus indicating the possibility to suppress the radiation-induced acceptor creation by material modification. Finally, we show that the experimental findings disagree in several important aspects with predictions made by microscopic defect kinetics models, leaving the physical background of some of the measured data as an open question

Effects of ambient oxygen concentration on soot temperature and concentration for biodiesel and diesel spray combustion

KAUST Repository

Zhang, Ji; Jing, Wei; Roberts, William L.; Fang, Tiegang

2015-01-01

during biodiesel and diesel spray combustion. The experiment was implemented in a constant volume chamber system, where the ambient oxygen concentration varied from 21 to 10% and the ambient temperature was kept to 1,000 K. A high speed two-color

Influence of the dissolved oxygen concentration on the penicillin biosynthetic pathway in steady-state cultures of Penicillium chrysogenum

DEFF Research Database (Denmark)

Henriksen, Claus Maxel; Nielsen, Jens Bredal; Villadsen, John

1997-01-01

The influence the of dissolved oxygen concentration on penicillin biosynthesis was studied in steady-state continuous cultures of a high-yielding strain of Penicillium chrysogenum operated at a dilution rate of 0.05 h-l. The dissolved oxygen concentration was varied between 0.019 and 0.344 m...... penicillin productivity decreases, and a value of 17 (mu mol/g of DW)/h was obtained when the dissolved oxygen concentration was 0.042 mM. A further lowering of the dissolved oxygen concentration to 0.019 mM resulted in the loss of penicillin production. However, penicillin productivity was instantly...

Control systems for the dissolved oxygen concentration in condensate- and feed-water systems in nuclear power plants

International Nuclear Information System (INIS)

Mikajiri, Motohiko; Hosaka, Seiichi.

1981-01-01

Purpose: To surely prevent the generation of corrosion products and contaminations in the systems thereby decreasing the exposure dose to operators in BWR type nuclear power plants. Constitution: Dissolved oxygen concentration in condensates is measured by a dissolved oxygen concentration meter disposed to the pipeway down stream of the condensator and the measured value is sent to an injection amount control mechanism for heater drain water. The control mechanism controls the injection amount from the injection mechanism that injection heater drain water from a feed-water heater to the liquid phase in the hot wall of the condensator. Thus, heater drawin water at high dissolved oxygen is injected to the condensates in the condensator which is de-airated and reduced with dissolved oxygen concentration, to maintain the dissolved oxygen concentration at a predetermined level, whereby stable oxide films are formed to the inner surface of the pipeways to prevent the generation of corrosion products such as rusts. (Furukawa, Y.)

Effect of varying concentrations of caffeine and ascorbic acid on the radiosensitivity of barley seed irradiated in oxygenated or oxygen-free hydration medium at 25 and 3700C

International Nuclear Information System (INIS)

Afzal, S.M.J.; Kesavan, P.C.

1977-01-01

The modification of radiosensitivity of barley seed with 1.75 x 10 -3 M and 3.8 x 10 -3 M concentrations of caffeine and ascorbic acid during irradiation in oxygenated and oxygen-free hydration medium was studied at 25 and 37 0 C, respectively. Both concentrations of caffeine and ascorbic acid afforded protection against oxic radiation damage which was maximal at 25 0 C. Caffeine effectively potentiated the anoxic component of damage but ascorbic acid had no influence at all. At 25 0 C there was no concentration-dependent effect of caffeine or ascorbic acid. At 37 0 C, there was no effect, whatsoever, of either concentration of ascorbic acid, whereas caffeine dramatically potentiated the radiation damage under both oxygenated and oxygen-free conditions, and the magnitude of potentiation was concentration-dependent. The possible reactivity of caffeine and ascorbic acid towards the precursors of oxygen-dependent and -independent components of damage in determining the mode and magnitudes of modification is discussed briefly. (author)

75 FR 739 - Use of Additional Portable Oxygen Concentrator Devices on Board Aircraft

Science.gov (United States)

2010-01-06

...;Prices of new books are listed in the first FEDERAL REGISTER issue of each #0;week. #0; #0; #0; #0;#0... approved by the Food and Drug Administration (FDA) reduce the risks typically associated with compressed... developed small portable oxygen concentrators (POC) that work by separating oxygen from nitrogen and other...

Hydrogen and oxygen concentrations in IXCs: A compilation

International Nuclear Information System (INIS)

Liljegren, L.M.; Terrones, G.T.; Melethil, P.K.

1996-06-01

This paper contains four reports and two internal letters that address the estimation of hydrogen and oxygen concentrations in ion exchange columns that treat the water of the K-East and K-West Basins at Hanford. The concern is the flammability of this mixture of gases and planning for safe transport during decommissioning. A transient will occur when the hydrogen filter is temporarily blocked by a sandbag. Analyses are provided for steady-state, transients, and for both wet and dry resins

Effect of different concentrations of oxygen on expression of sigma 1 receptor and superoxide dismutases in human colon adenocarcinoma cell lines.

Science.gov (United States)

Skrzycki, Michał; Czeczot, Hanna; Mielczarek-Puta, Magdalena; Otto-Ślusarczyk, Dagmara; Graboń, Wojciech

2017-06-01

Tumor cells due to distance from capillary vessels exist in different oxygenation conditions (anoxia, hypoxia, normoxia). Changes in cell oxygenation lead to reactive oxygen species production and oxidative stress. Sigma 1 receptor (Sig1R) is postulated to be stress responding agent and superoxide dismutases (SOD1 and SOD2) are key antioxidant enzymes. It is possible that they participate in tumor cells adaptation to different concentrations of oxygen. Evaluation of Sig1R, SOD1, and SOD2 expression in different concentrations of oxygen (1%, 10%, 21%) in colon adenocarcinoma cell lines. SW480 (primary adenocarcinoma) and SW620 (metastatic) cell lines were cultured in standard conditions in Dulbecco's modified Eagle's medium for 5 days, and next cultured in Hypoxic Chamber in 1% O 2 , 10% O 2 , 21% O 2 . Number of living cells was determined by trypan blue assay. Level of mRNA for Sig1R, SOD1, and SOD2 was determined by standard PCR method. Statistical analysis was conducted using Statistica 10.1 software. We observed significant changes in expression of Sig1R, SOD1, SOD2 due to different oxygen concentrations. ANOVA analysis revealed significant interactions between studied parameters mainly in hypoxia conditions in SW480 cells and between Sig1R and SOD2 in SW620 cells. It also showed that changes in expression of studied proteins depend significantly on type of the cell line. Changes of Sig1R and SOD2 expression point to mitochondria as main organelle responsible for survival of tumor cells exposed to hypoxia or oxidative stress. Studied proteins are involved in intracellular response to stress related with different concentrations of oxygen.

Ammonium and nitrite oxidation at nanomolar oxygen concentrations in oxygen minimum zone waters.

Science.gov (United States)

Bristow, Laura A; Dalsgaard, Tage; Tiano, Laura; Mills, Daniel B; Bertagnolli, Anthony D; Wright, Jody J; Hallam, Steven J; Ulloa, Osvaldo; Canfield, Donald E; Revsbech, Niels Peter; Thamdrup, Bo

2016-09-20

A major percentage of fixed nitrogen (N) loss in the oceans occurs within nitrite-rich oxygen minimum zones (OMZs) via denitrification and anammox. It remains unclear to what extent ammonium and nitrite oxidation co-occur, either supplying or competing for substrates involved in nitrogen loss in the OMZ core. Assessment of the oxygen (O2) sensitivity of these processes down to the O2 concentrations present in the OMZ core (Chile at manipulated O2 levels between 5 nmol⋅L(-1) and 20 μmol⋅L(-1) Rates of both processes were detectable in the low nanomolar range (5-33 nmol⋅L(-1) O2), but demonstrated a strong dependence on O2 concentrations with apparent half-saturation constants (Kms) of 333 ± 130 nmol⋅L(-1) O2 for ammonium oxidation and 778 ± 168 nmol⋅L(-1) O2 for nitrite oxidation assuming one-component Michaelis-Menten kinetics. Nitrite oxidation rates, however, were better described with a two-component Michaelis-Menten model, indicating a high-affinity component with a Km of just a few nanomolar. As the communities of ammonium and nitrite oxidizers were similar to other OMZs, these kinetics should apply across OMZ systems. The high O2 affinities imply that ammonium and nitrite oxidation can occur within the OMZ core whenever O2 is supplied, for example, by episodic intrusions. These processes therefore compete with anammox and denitrification for ammonium and nitrite, thereby exerting an important control over nitrogen loss.

The design of a PC-based real-time system for monitoring Methane and Oxygen concentration in biogas production

Science.gov (United States)

Yantidewi, M.; Muntini, M. S.; Deta, U. A.; Lestari, N. A.

2018-03-01

Limited fossil fuels nowadays trigger the development of alternative energy, one of which is biogas. Biogas is one type of bioenergy in the form of fermented gases of organic materials such as animal waste. The components of gases present in biogas and affect the biogas production are various, such as methane and oxygen. The biogas utilization will be more optimal if both gases concentration (in this case is methane and oxygen concentration) can be monitored. Therefore, this research focused on designing the monitoring system of methane and oxygen concentration in biogas production in real-time. The results showed that the instrument system was capable of monitoring and recording the data of gases (methane and oxygen) concentration in biogas production in every second.

Comparison of portable oxygen concentrators in a simulated airplane environment.

Science.gov (United States)

Fischer, Rainald; Wanka, Eva R; Einhaeupl, Franziska; Voll, Klaus; Schiffl, Helmut; Lang, Susanne M; Gruss, Martin; Ferrari, Uta

2013-01-01

Portable oxygen concentrators (POC) are highly desirable for patients with lung disease traveling by airplane, as these devices allow theoretically much higher travel times if additional batteries can be used. However, it is unclear whether POCs produce enough oxygen in airplanes at cruising altitude, even if complying with aviation regulations. We evaluated five frequently used POCs (XPO2 (Invacare, USA), Freestyle (AirSep C., USA), Evergo (Philipps Healthcare, Germany), Inogen One (Inogen, USA), Eclipse 3 (Sequal, USA)) at an altitude of 2650 m (as simulated airplane environment) in 11 patients with chronic obstructive lung disease (COPD) and compared theses POCs with the standard oxygen system (WS120, EMS Ltd., Germany) used by Lufthansa. Oxygen was delivered by each POC for 30 min to each patient at rest, blood gases were then drawn from the arterialized ear lobe. All POCs were able to deliver enough oxygen to increase the PaO(2) of our subjects by at least 1.40 kPa (10 mmHg). However, to achieve this increase, the two most lightweight POCs (Freestyle and Invacare XPO2) had to be run at their maximum level. This causes a significant reduction of battery life. The three other POCs (EverGo, Inogen One, Eclipse 3) and the WS120 were able to increase the PaO(2) by more than 2.55 kPa (20 mmHg), which provides extra safety for patients with more severe basal hypoxemia. When choosing the right oxygen system for air travel in patients in COPD, not only weight, but also battery life and maximum possible oxygen output must be considered carefully. Copyright © 2012 Elsevier Ltd. All rights reserved.

Water quality and processes affecting dissolved oxygen concentrations in the Blackwater River, Canaan Valley, West Virginia

Science.gov (United States)

Waldron, M.C.; Wiley, J.B.

1996-01-01

The water quality and environmental processes affecting dissolved oxygen were determined for the Blackwater River in Canaan Valley, West Virginia. Canaan Valley is oval-shaped (14 miles by 5 miles) and is located in the Allegheny Mountains at an average elevation of 3,200 feet above sea level. Tourism, population, and real estate development have increased in the past two decades. Most streams in Canaan Valley are a dilute calcium magnesium bicarbonate-type water. Streamwater typicaly was soft and low in alkalinity and dissolved solids. Maximum values for specific conductance, hardness, alkalinity, and dissolved solids occurred during low-flow periods when streamflow was at or near baseflow. Dissolved oxygen concentrations are most sensitive to processes affecting the rate of reaeration. The reaeration is affected by solubility (atmospheric pressure, water temperature, humidity, and cloud cover) and processes that determine stream turbulence (stream depth, width, velocity, and roughness). In the headwaters, photosynthetic dissolved oxygen production by benthic algae can result in supersaturated dissolved oxygen concentrations. In beaver pools, dissolved oxygen consumption from sediment oxygen demand and carbonaceous biochemical oxygen demand can result in dissolved oxygen deficits.

Startup and oxygen concentration effects in a continuous granular mixed flow autotrophic nitrogen removal reactor.

Science.gov (United States)

Varas, Rodrigo; Guzmán-Fierro, Víctor; Giustinianovich, Elisa; Behar, Jack; Fernández, Katherina; Roeckel, Marlene

2015-08-01

The startup and performance of the completely autotrophic nitrogen removal over nitrite (CANON) process was tested in a continuously fed granular bubble column reactor (BCR) with two different aeration strategies: controlling the oxygen volumetric flow and oxygen concentration. During the startup with the control of oxygen volumetric flow, the air volume was adjusted to 60mL/h and the CANON reactor had volumetric N loadings ranging from 7.35 to 100.90mgN/Ld with 36-71% total nitrogen removal and high instability. In the second stage, the reactor was operated at oxygen concentrations of 0.6, 0.4 and 0.2mg/L. The best condition was 0.2 mgO2/L with a total nitrogen removal of 75.36% with a CANON reactor activity of 0.1149gN/gVVSd and high stability. The feasibility and effectiveness of CANON processes with oxygen control was demonstrated, showing an alternative design tool for efficiently removing nitrogen species. Copyright © 2015 Elsevier Ltd. All rights reserved.

Oxygenation level and hemoglobin concentration in experimental tumor estimated by diffuse optical spectroscopy

Science.gov (United States)

Orlova, A. G.; Kirillin, M. Yu.; Volovetsky, A. B.; Shilyagina, N. Yu.; Sergeeva, E. A.; Golubiatnikov, G. Yu.; Turchin, I. V.

2017-07-01

Using diffuse optical spectroscopy the level of oxygenation and hemoglobin concentration in experimental tumor in comparison with normal muscle tissue of mice have been studied. Subcutaneously growing SKBR-3 was used as a tumor model. Continuous wave fiber probe diffuse optical spectroscopy system was employed. Optical properties extraction approach was based on diffusion approximation. Decreased blood oxygen saturation level and increased total hemoglobin content were demonstrated in the neoplasm. The main reason of such differences between tumor and norm was significant elevation of deoxyhemoglobin concentration in SKBR-3. The method can be useful for diagnosis of tumors as well as for study of blood flow parameters of tumor models with different angiogenic properties.

Dependence of Initial Oxygen Concentration on Ozone Yield Using Inductive Energy Storage System Pulsed Power Generator

Science.gov (United States)

Go, Tomio; Tanaka, Yasushi; Yamazaki, Nobuyuki; Mukaigawa, Seiji; Takaki, Koichi; Fujiwara, Tamiya

Dependence of initial oxygen concentration on ozone yield using streamer discharge reactor driven by an inductive energy storage system pulsed power generator is described in this paper. Fast recovery type diodes were employed as semiconductor opening switch to interrupt a circuit current within 100 ns. This rapid current change produced high-voltage short pulse between a secondary energy storage inductor. The repetitive high-voltage short pulse was applied to a 1 mm diameter center wire electrode placed in a cylindrical pulse corona reactor. The streamer discharge successfully occurred between the center wire electrode and an outer cylinder ground electrode of 2 cm inner diameter. The ozone was produced with the streamer discharge and increased with increasing pulse repetition rate. The ozone yield changed in proportion to initial oxygen concentration contained in the injected gas mixture at 800 ns forward pumping time of the current. However, the decrease of the ozone yield by decreasing oxygen concentration in the gas mixture at 180 ns forward pumping time of the current was lower than the decrease at 800 ns forward pumping time of the current. This dependence of the initial oxygen concentration on ozone yield at 180 ns forward pumping time is similar to that of dielectric barrier discharge reactor.

Steady-state ozone concentration in radiation induced noble gas-oxygen discharges

International Nuclear Information System (INIS)

Elsayed-Ali, H.E.; Miley, G.H.

1985-01-01

Measurements of steady-state ozone concentrations in continuous radiation induced noble gas-O 2 and noble gas-O 2 -SF 6 mixtures has been accomplished. The discharges were created through the bombardment of the gases with energetic particles from the boron-10 (n,α) lithium-7 nuclear reaction. Three noble gases were studied, He, Ne, and Ar at partial pressures of few hundred Torr. The dose rates studied were in the order of 10 15 eV.cm -3 .s -1 . The experimental apparatus and proceedure were previously described. The experimentally observed stead-state ozone concentrations in noble gas-O 2 discharges were about an order of magnitude lower than that observed for oxygen radiolysis at similar dose rates. These results were physically explained by an enhanced role of negative ionic reactions with ozone causing its destruction. In noble gas-O 2 -SF 6 mixtures, the steady-state ozone concentrations were found to be significantly higher (3-6 times) than that without the SF 6 addition. This observation was contrary to only a small increase observed after SF 6 addition to a few hundred Torr oxygen and is explained by an enhanced rate of electron dissociative attachment of ozone in noble gas-O 2 discharges

Oxygen concentration modulates cellular senescence and autophagy in human trophoblast cells.

Science.gov (United States)

Seno, Kotomi; Tanikawa, Nao; Takahashi, Hironori; Ohkuchi, Akihide; Suzuki, Hirotada; Matsubara, Shigeki; Iwata, Hisataka; Kuwayama, Takehito; Shirasuna, Koumei

2018-02-15

We investigated the effect of oxygen concentrations on cellular senescence and autophagy and examined the role of autophagy in human trophoblast cells. Human first-trimester trophoblast cells (Sw.71) were incubated under 21%, 5%, or 1% O 2 concentrations for 24 hours. We examined the extent of senescence caused using senescence-associated β-galactosidase (SA-β-Gal) and senescence-associated secretory phenotype (SASP) as markers. Moreover, we examined the role of autophagy in causing cellular senescence using an autophagy inhibitor (3-methyladenine, 3MA). Physiological normoxia (5% O 2 ) decreased SA-β-Gal-positive cells and SASP including interleukin-6 (IL-6) and IL-8 compared with cultured cells in 21% O 2 . Pathophysiological hypoxia (1% O 2 ) caused cytotoxicity, including extracellular release of ATP and lactate dehydrogenase, and decreased senescence phenotypes. 3MA-treated trophoblast cells significantly suppressed senescence markers (SA-β-Gal-positive cells and SASP secretion) in O 2 -independent manner. We conclude that O 2 concentration modulates cellular senescence phenotypes regulating autophagy in the human trophoblast cells. Moreover, inhibiting autophagy suppresses cellular senescence, suggesting that autophagy contributes to oxygen stress-induced cellular senescence. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Radiation-induced strand-breaks and DNA-protein crosslinks depend predominantly on the dose, oxygen concentration and repair time

International Nuclear Information System (INIS)

Wheeler, K.T.; Miyagi, Y.; Zhang, H.

1995-01-01

It has been known for many years that the DNA damage produced by ionizing radiation depends upon the oxygen concentration around the DNA. For example, the number of DNA strand-breaks (SBs) formed per unit dose decreases at low oxygen concentrations, and the number of DNA-protein crosslinks formed per unit dose increases at low oxygen concentrations. If radiation-induced SBs and DPCs are to be useful for detecting and/or quantifying hypoxic cells in solid tumors, the formation of these lesions must depend predominantly on the oxygen concentration around the DNA. All other physical, biological, and physiological factors must either be controllable or have little influence on the assay used to measure these lesions. This paper is a summary of the authors' recent experiments to determine if the radiation-induced SBs and DPCs measured by alkaline elution may be used to estimate the hypoxic fraction or fractional hypoxic volume of solid tumors

Detection of Molecular Oxygen at Low Concentrations Using Quartz Enhanced Photoacoustic Spectroscopy

Directory of Open Access Journals (Sweden)

Andreas Pohlkötter

2010-09-01

Full Text Available Molecular oxygen is detected at low concentrations using photoacoustic spectroscopy despite its unfavorable photoacoustic properties. The system consists of a seed laser diode, a tapered amplifier and a quartz tuning fork based spectrophone, thus employing quartz enhanced photoacoustic spectroscopy (QEPAS. With this system a detection limit of 13 ppm is reached with a compact and long term stable setup. Further improvement of the detection limit is possible by adding suitable gases to the sample gas that promote the radiationless de-excitation of the oxygen molecules.

Singlet oxygen quenching by oxygen in tetraphenyl-porphyrin solutions

International Nuclear Information System (INIS)

Dedic, Roman; Korinek, Miloslav; Molnar, Alexander; Svoboda, Antonin; Hala, Jan

2006-01-01

Time-resolved measurement of singlet oxygen infrared phosphorescence is a powerful tool for determination of quantum yields and kinetics of its photosensitization. This technique was employed to investigate in detail the previously observed effect of singlet oxygen quenching by oxygen. The question whether the singlet oxygen is quenched by oxygen in ground or in excited state was addressed by study of two complementary dependencies of singlet oxygen lifetimes: on dissolved oxygen concentration and on excitation intensity. Oxygen concentration dependence study of meso-tetra(4-sulphonato)phenylporphyrin (TPPS 4 ) phosphorescence kinetics showed linearity of the dependence of TPPS 4 triplet state rate-constant. Corresponding bimolecular quenching constant of (1.5±0.1)x10 9 l/mol s was obtained. On the other hand, rate constants of singlet oxygen depopulation exhibit nonlinear dependence on oxygen concentration. Comparison of zero oxygen concentration-extrapolated value of singlet oxygen lifetime of (6.5±0.4) μs to (3.7±0.1) μs observed under air-saturated conditions indicates importance of the effect of quenching of singlet oxygen by oxygen. Upward-sloping dependencies of singlet oxygen depopulation rate-constant on excitation intensity evidence that singlet oxygen is predominantly quenched by oxygen in excited singlet state

An in silico analysis of oxygen uptake of a mild COPD patient during rest and exercise using a portable oxygen concentrator

Directory of Open Access Journals (Sweden)

Katz I

2016-09-01

Full Text Available Ira Katz,1,2 Marine Pichelin,1 Spyridon Montesantos,1 Min-Yeong Kang,3 Bernard Sapoval,3,4 Kaixian Zhu,5 Charles-Philippe Thevenin,5 Robert McCoy,6 Andrew R Martin,7 Georges Caillibotte1 1Medical R&D, Air Liquide Santé International, Centre de Recherche Paris-Saclay, Les Loges-en-Josas, France; 2Department of Mechanical Engineering, Lafayette College, Easton, PA, USA; 3Physique de la Matière Condensée, CNRS, Ecole Polytechnique, Palaiseau, 4Centre de Mathématiques et de leurs Applications, CNRS, UniverSud, Cachan, 5Centre Explor!, Air Liquide Healthcare, Gentilly, France; 6Valley Inspired Products, Inc, Apple Valley, MN, USA; 7Department of Mechanical Engineering, University of Alberta, Edmonton, AB, Canada Abstract: Oxygen treatment based on intermittent-flow devices with pulse delivery modes available from portable oxygen concentrators (POCs depends on the characteristics of the delivered pulse such as volume, pulse width (the time of the pulse to be delivered, and pulse delay (the time for the pulse to be initiated from the start of inhalation as well as a patient’s breathing characteristics, disease state, and respiratory morphology. This article presents a physiological-based analysis of the performance, in terms of blood oxygenation, of a commercial POC at different settings using an in silico model of a COPD patient at rest and during exercise. The analysis encompasses experimental measurements of pulse volume, width, and time delay of the POC at three different settings and two breathing rates related to rest and exercise. These experimental data of device performance are inputs to a physiological-based model of oxygen uptake that takes into account the real dynamic nature of gas exchange to illustrate how device- and patient-specific factors can affect patient oxygenation. This type of physiological analysis that considers the true effectiveness of oxygen transfer to the blood, as opposed to delivery to the nose (or mouth, can be

Physiological oxygen concentration alters glioma cell malignancy and responsiveness to photodynamic therapy in vitro.

Science.gov (United States)

Albert, Ina; Hefti, Martin; Luginbuehl, Vera

2014-11-01

The partial pressure of oxygen (pO2) in brain tumors ranges from 5 to 15%. Nevertheless, the majority of in vitro experiments with glioblastoma multiforme (GBM) cell lines are carried out under an atmospheric pO2 of 19 to 21%. Recently, 5-aminolevulinic acid (5-ALA), a precursor of protoporphyrin IX (PpIX), has been introduced to neurosurgery to allow for photodynamic diagnosis and photodynamic therapy (PDT) in high-grade gliomas. Here, we investigate whether low pO2 affects GBM cell physiology, PpIX accumulation, or PDT efficacy. GBM cell lines (U-87 MG and U-251 MG) were cultured under atmospheric (pO2  =  19%) and physiological (pO2  =  9%) oxygen concentrations. PpIX accumulation and localization were investigated, and cell survival and cell death were observed following in vitro PDT. A physiological pO2 of 9% stimulated GBM cell migration, increased hypoxia-inducible factor (HIF)-1 alpha levels, and elevated resistance to camptothecin in U-87 MG cells compared to cultivation at a pO2 of 19%. This oxygen reduction did not alter 5-ALA-induced intracellular PpIX accumulation. However, physiological pO2 changed the responsiveness of U-87 MG but not of U-251 MG cells to in vitro PDT. Around 20% more irradiation light was required to kill U-87 MG cells at physiological pO2, resulting in reduced lactate dehydrogenase (LDH) release (one- to two-fold) and inhibition of caspase 3 activation. Reduction of oxygen concentration from atmospheric to a more physiological level can influence the malignant behavior and survival of GBM cell lines after in vitro PDT. Therefore, precise oxygen concentration control should be considered when designing and performing experiments with GBM cells.

Comparison of domiciliary oxygen using liquid oxygen and concentrator in northern Taiwan

Directory of Open Access Journals (Sweden)

Chien-Ling Su

2014-01-01

Conclusion: Patients in the LOG used oxygen for longer hours, went on more outings, and were more likely to travel with oxygen than patients in the OCG. Being ambulatory with liquid oxygen might enable patients with COPD to walk more effectively.

Steady-state ozone concentrations in radiation induced noble gas-oxygen discharges

International Nuclear Information System (INIS)

Elsayed-Ali, H.E.; Miley, G.H.

1985-01-01

Measurements of steady-state ozone concentrations in continuous radiation induced noble gas-O/sub 2/ and noble gas-o/sub 2/-SF/sub 6/ mixtures has been accomplished. The discharges were created through the bombardment of the gases with energetic particles from the boron-10 (n,α) lithium-7 nuclear reaction. Three noble gases were studied, He, Ne, and Ar at partial pressures of few hundred Torr. The dose rates studied were in the order of 10/sup 15/ eV . cm/sup -3/ . s/sup -1/. The experimental apparatus and procedure were previously described. The experimentally observed steady-state ozone concentrations in noble gas-O/sub 2/ discharges were about an order of magnitude lower than that observed for oxygen radiolysis at similar dose rates. These results were physically explained by an enhanced role of negative ionic reactions with ozone causing its destruction. In noble gas-O/sub 2/-SF/sub 6/ mixtures, the steady-state ozone concentrations were found to be significantly higher (3-6 times) than that without the SF/sub 6/ addition. This observation was contrary to only a small increase observed after SF/sub 6/ addition to a few hundred Torr oxygen and is explained by an enhanced rate of electron dissociative attachment of ozone in noble gas-O/sub 2/ discharges

Physiology of Aspergillus niger in Oxygen-Limited Continuous Cultures: Influence of Aeration, Carbon Source Concentration and Dilution Rate

DEFF Research Database (Denmark)

Diano, Audrey; Peeters, J.; Dynesen, Jens Østergaard

2009-01-01

In industrial production of enzymes using the filamentous fungus Aspergilhis niger supply of sufficient oxygen is often a limitation, resulting in the formation of by-products such as polyols. In order to identify the mechanisms behind formation of the different by-products we studied the effect...... of low oxygen availability, at different carbon source concentrations and at different specific growth rates, on the metabolism of A. niger, using continuous cultures. The results show that there is an increase in the production of tricarboxylic acid (TCA) cycle intermediates at low oxygen concentrations...

Adsorption/desorption of low concentration of carbonyl sulfide by impregnated activated carbon under micro-oxygen conditions

International Nuclear Information System (INIS)

Wang, Xueqian; Qiu, Juan; Ning, Ping; Ren, Xiaoguang; Li, Ziyan; Yin, Zaifei; Chen, Wei; Liu, Wei

2012-01-01

Highlights: ► Carbonyl sulfide can be catalytic oxidized by micro-oxygen in the off-gas. ► How to use the trace oxygen for the oxidation of carbonyl sulfide was a challenge. ► The SO 4 2− species in the adsorbent sample were generated by a catalytic oxidation process. - Abstract: Activated carbon modified with different impregnants has been studied for COS removal efficiency under micro-oxygen conditions. Activated carbon modified with Cu(NO 3 ) 2 –CoPcS–KOH (denoted as Cu–Co–KW) is found to have markedly enhanced adsorption purification ability. In the adsorption purification process, the reaction temperature, oxygen concentration, and relative humidity of the gas are determined to be three crucial factors. A breakthrough of 43.34 mg COS/g adsorbent at 60 °S and 30% relative humidity with 1.0% oxygen is shown in Cu–Co–KW for removing COS. The structures of the activated carbon samples are characterized using nitrogen adsorption, and their surface chemical structures are analyzed with X-ray photoelectron spectroscopy (XPS). Modification of Cu(NO 3 ) 2 –CoPcS–KOH appears to improve the COS removal capacity significantly, during which, SO 4 2− is presumably formed, strongly adsorbed, and present in the micropores ranging from 0.7 to 1.5 nm. TPD is used to identify the products containing sulfur species on the carbon surface, where SO 2 and COS are detected in the effluent gas generated from exhausted Cu–Co–KW (denoted Cu–Co–KWE). According to the current study results, the activated carbon impregnated with Cu(NO 3 ) 2 –CoPcS–KOH promises a good candidate for COS adsorbent, with the purified gas meeting requirements for desirable chemical feed stocks.

Adsorption/desorption of low concentration of carbonyl sulfide by impregnated activated carbon under micro-oxygen conditions

Energy Technology Data Exchange (ETDEWEB)

Wang, Xueqian, E-mail: wxqian3000@yahoo.com.cn [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Qiu, Juan; Ning, Ping; Ren, Xiaoguang; Li, Ziyan; Yin, Zaifei; Chen, Wei; Liu, Wei [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

2012-08-30

Highlights: Black-Right-Pointing-Pointer Carbonyl sulfide can be catalytic oxidized by micro-oxygen in the off-gas. Black-Right-Pointing-Pointer How to use the trace oxygen for the oxidation of carbonyl sulfide was a challenge. Black-Right-Pointing-Pointer The SO{sub 4}{sup 2-} species in the adsorbent sample were generated by a catalytic oxidation process. - Abstract: Activated carbon modified with different impregnants has been studied for COS removal efficiency under micro-oxygen conditions. Activated carbon modified with Cu(NO{sub 3}){sub 2}-CoPcS-KOH (denoted as Cu-Co-KW) is found to have markedly enhanced adsorption purification ability. In the adsorption purification process, the reaction temperature, oxygen concentration, and relative humidity of the gas are determined to be three crucial factors. A breakthrough of 43.34 mg COS/g adsorbent at 60 Degree-Sign S and 30% relative humidity with 1.0% oxygen is shown in Cu-Co-KW for removing COS. The structures of the activated carbon samples are characterized using nitrogen adsorption, and their surface chemical structures are analyzed with X-ray photoelectron spectroscopy (XPS). Modification of Cu(NO{sub 3}){sub 2}-CoPcS-KOH appears to improve the COS removal capacity significantly, during which, SO{sub 4}{sup 2-} is presumably formed, strongly adsorbed, and present in the micropores ranging from 0.7 to 1.5 nm. TPD is used to identify the products containing sulfur species on the carbon surface, where SO{sub 2} and COS are detected in the effluent gas generated from exhausted Cu-Co-KW (denoted Cu-Co-KWE). According to the current study results, the activated carbon impregnated with Cu(NO{sub 3}){sub 2}-CoPcS-KOH promises a good candidate for COS adsorbent, with the purified gas meeting requirements for desirable chemical feed stocks.

Aerobic growth at nanomolar oxygen concentrations

DEFF Research Database (Denmark)

Stolper, Daniel Aaron; Revsbech, Niels Peter; Canfield, Donald Eugene

2010-01-01

that Escherichia coli K-12, chosen for its well-understood biochemistry, rapid growth rate, and low-oxygen-affinity terminal oxidase, grows at oxygen levels of ≤ 3 nM, two to three orders of magnitude lower than previously observed for aerobes. Our study expands both the environmental range and temporal history...... of aerobic organisms....

Aerobic growth at nanomolar oxygen concentrations

DEFF Research Database (Denmark)

Stolper, Daniel; Revsbech, Niels Peter; Canfield, Donald Eugene

2010-01-01

that Escherichia coli K-12, chosen for its well-understood biochemistry, rapid growth rate, and low-oxygen-affinity terminal oxidase, grows at oxygen levels of ≤ 3 nM, two to three orders of magnitude lower than previously observed for aerobes. Our study expands both the environmental range and temporal history...... of aerobic organisms....

Relation between flows and dissolved oxygen in the Roanoke River between Roanoke Rapids Dam and Jamesville, North Carolina, 2005-2009

Science.gov (United States)

Wehmeyer, Loren L.; Wagner, Chad R.

2011-01-01

The relation between dam releases and dissolved-oxygen concentration, saturation and deficit, downstream from Roanoke Rapids Dam in North Carolina was evaluated from 2005 to 2009. Dissolved-oxygen data collected at four water-quality monitoring stations downstream from Roanoke Rapids Dam were used to determine if any statistical relations or discernible quantitative or qualitative patterns linked Roanoke River in-stream dissolved-oxygen levels to hydropower peaking at Roanoke Rapids Dam. Unregulated tributaries that inundate and drain portions of the Roanoke River flood plain are crucial in relation to in-stream dissolved oxygen. Hydropower peaking from 2005 to 2009 both inundated and drained portions of the flood plain independently of large storms. The effects of these changes in flow on dissolved-oxygen dynamics are difficult to isolate, however, because of (1) the variable travel time for water to move down the 112-mile reach of the Roanoke River from Roanoke Rapids Dam to Jamesville, North Carolina, and (2) the range of in-situ conditions, particularly inundation history and water temperature, in the flood plain. Statistical testing was conducted on the travel-time-adjusted hourly data measured at each of the four water-quality stations between May and November 2005-2009 when the weekly mean flow was 5,000-12,000 cubic feet per second (a range when Roanoke Rapids Dam operations likely affect tributary and flood-plain water levels). Results of this statistical testing indicate that at the 99-percent confidence interval dissolved-oxygen levels downstream from Roanoke Rapids Dam were lower during peaking weeks than during non-peaking weeks in three of the five years and higher in one of the five years; no data were available for weeks with peaking in 2007. For the four years of statistically significant differences in dissolved oxygen between peaking and non-peaking weeks, three of the years had statistically signficant differences in water temperature. Years

Modification of radiation sensitivity: the oxygen effect

International Nuclear Information System (INIS)

Quintiliani, M.

1979-01-01

Four fundamental aspects of the oxygen effect in radiobiology are reviewed, with emphasis on single cell systems: (1) Radiosensitivity in relation to oxygen concentration. In many biological systems, this relationship is remarkably well represented by the well-known Howard-Flanders/Alper formula. Often, however, the degree of uncertainty associated with the estimation of the value of K in the formula is fairly high. Recent data on V79-753B cells indicate a biphasic influence of oxygen concentration on radiosensitivity that cannot be described in terms of the Howard-Flanders/Alper model. (2) The oxygen effect in relation to survival level. The influence of very low oxygen concentrations on the shoulder of the survival curves of irradiated cells is still controversial. Also, the oxygen dependence of repair processes for sublethal and potentially lethal damage need to be better defined. (3) Time-scale of the oxygen effect. All the experimental data obtained with the use of fast techniques indicate that the time scale of the oxygen effect is consistent with that of free radical reactions. This appears to be compatible with the hypothesis that oxygen acts by fixation of a radiation-induced reversible damage. The existence of two types of damage with different rates of decay is suggested, both in bacterial and mammalian cells. (4) Molecular mechanisms of the oxygen effect. In spite of the very large literature on this subject, the identification of the detailed molecular mechanisms of the oxygen effect must still be considered goals for future research

Relations between oxygen and hydrogen generated by radiolysis in the systems of a CANDU 600

International Nuclear Information System (INIS)

Romano, Christian; Chocron, Mauricio; Urrutia, Guillermo

1999-01-01

The water that constitutes the coolant of the primary heat transport system, the moderator and the liquid control zones, decomposed under radiation producing as stable products oxygen, hydrogen and hydrogen peroxide throughout a complex mechanisms of radiolysis that involves ions and free radicals. These compound formed in different proportions alters the chemical control established for each system which purpose is to minimize the corrosion of the structural materials. In the present paper have been presented results of the modelling of the mentioned processes and it has been found that in the absence of a vapor phase, a relatively low concentration of hydrogen added to the water would be sufficient to control the formation of oxygen and hydrogen peroxide. The last species however, would remain in relatively high values inside a coolant fuel channel in the reactor core. (author)

Numerical modelling of pyrolysis in normal and reduced oxygen concentration

International Nuclear Information System (INIS)

Kacem, Ahmed

2016-01-01

The predictive capability of computational fluid dynamics (CFD) fire models depends on the accuracy with which the source term due to fuel pyrolysis can be determined. The pyrolysis rate is a key parameter controlling fire behavior, which in turn drives the heat feedback from the flame to the fuel surface. In the present study an in-depth pyrolysis model of a semi-transparent solid fuel (here, clear polymethyl methacrylate or PMMA) with spectrally-resolved radiation and a moving gas/solid interface was coupled with the CFD code ISIS of the IRSN which included turbulence, combustion and radiation for the gas phase. A combined genetic algorithm/pyrolysis model was used with Cone Calorimeter data from a pure pyrolysis experiment to estimate a unique set of kinetic parameters for PMMA pyrolysis. In order to validate the coupled model, ambient air flaming experiments were conducted on square slabs of PMMA with side lengths of 10, 20 and 40 cm. From measurements at the center of the slab, it was found that i) for any sample size, the experimental regression rate becomes almost constant with time, and ii) although the radiative and total heat transfers increase significantly with the sample size, the radiative contribution to the total heat flux remains almost constant (∼80%). Coupled model results show a fairly good agreement with the literature and with current measurements of the heat fluxes, gas temperature and regressing surface rate at the center of the slabs. Discrepancies between predicted and measured total pyrolysis rate are observed, which result from the underestimation of the flame heat flux feedback at the edges of the slab, as confirmed by the comparison between predicted and observed topography of burned samples. Predicted flame heights based on a threshold temperature criterion were found to be close to those deduced from the correlation of Heskestad. Finally, in order to predict the pyrolysis of PMMA under reduced ambient oxygen concentration, a two

Plasma ATP concentration and venous oxygen content in the forearm during dynamic handgrip exercise

Directory of Open Access Journals (Sweden)

Askew Christopher D

2009-12-01

Full Text Available Abstract Background It has been proposed that adenosine triphosphate (ATP released from red blood cells (RBCs may contribute to the tight coupling between blood flow and oxygen demand in contracting skeletal muscle. To determine whether ATP may contribute to the vasodilatory response to exercise in the forearm, we measured arterialised and venous plasma ATP concentration and venous oxygen content in 10 healthy young males at rest, and at 30 and 180 seconds during dynamic handgrip exercise at 45% of maximum voluntary contraction (MVC. Results Venous plasma ATP concentration was elevated above rest after 30 seconds of exercise (P Conclusions Collectively these results indicate that ATP in the plasma originated from the muscle microcirculation, and are consistent with the notion that deoxygenation of the blood perfusing the muscle acts as a stimulus for ATP release. That ATP concentration was elevated just 30 seconds after the onset of exercise also suggests that ATP may be a contributing factor to the blood flow response in the transition from rest to steady state exercise.

Fluorescence lifetime imaging of oxygen in dental biofilm

Science.gov (United States)

Gerritsen, Hans C.; de Grauw, Cees J.

2000-12-01

Dental biofilm consists of micro-colonies of bacteria embedded in a matrix of polysaccharides and salivary proteins. pH and oxygen concentration are of great importance in dental biofilm. Both can be measured using fluorescence techniques. The imaging of dental biofilm is complicated by the thickness of the biofilms that can be up to several hundred micrometers thick. Here, we employed a combination of two-photon excitation microscopy with fluorescence lifetime imaging to quantify the oxygen concentration in dental biofilm. Collisional quenching of fluorescent probes by molecular oxygen leads to a reduction of the fluorescence lifetime of the probe. We employed this mechanism to measure the oxygen concentration distribution in dental biofilm by means of fluorescence lifetime imaging. Here, TRIS Ruthenium chloride hydrate was used as an oxygen probe. A calibration procedure on buffers was use to measure the lifetime response of this Ruthenium probe. The results are in agreement with the Stern-Volmer equation. A linear relation was found between the ratio of the unquenched and the quenched lifetime and the oxygen concentration. The biofilm fluorescence lifetime imaging results show a strong oxygen gradient at the buffer - biofilm interface and the average oxygen concentration in the biofilm amounted to 50 μM.

Impacts of nitric oxide and superoxide on renal medullary oxygen transport and urine concentration

Science.gov (United States)

Edwards, Aurélie; Layton, Anita T.

2015-01-01

The goal of this study was to investigate the reciprocal interactions among oxygen (O2), nitric oxide (NO), and superoxide (O2−) and their effects on medullary oxygenation and urinary output. To accomplish that goal, we developed a detailed mathematical model of solute transport in the renal medulla of the rat kidney. The model represents the radial organization of the renal tubules and vessels, which centers around the vascular bundles in the outer medulla and around clusters of collecting ducts in the inner medulla. Model simulations yield significant radial gradients in interstitial fluid oxygen tension (Po2) and NO and O2− concentration in the OM and upper IM. In the deep inner medulla, interstitial fluid concentrations become much more homogeneous, as the radial organization of tubules and vessels is not distinguishable. The model further predicts that due to the nonlinear interactions among O2, NO, and O2−, the effects of NO and O2− on sodium transport, osmolality, and medullary oxygenation cannot be gleaned by considering each solute's effect in isolation. An additional simulation suggests that a sufficiently large reduction in tubular transport efficiency may be the key contributing factor, more so than oxidative stress alone, to hypertension-induced medullary hypoxia. Moreover, model predictions suggest that urine Po2 could serve as a biomarker for medullary hypoxia and a predictor of the risk for hospital-acquired acute kidney injury. PMID:25651567

Digitized Onondaga Lake Dissolved Oxygen Concentrations and Model Simulated Values using Bayesian Monte Carlo Methods

Data.gov (United States)

U.S. Environmental Protection Agency — The dataset is lake dissolved oxygen concentrations obtained form plots published by Gelda et al. (1996) and lake reaeration model simulated values using Bayesian...

Influence of dissolved oxygen concentration on the toxicity of potassium cyanide to rainbow trout. [Salmo gairdneri

Energy Technology Data Exchange (ETDEWEB)

Downing, K M

1954-01-01

The present work was undertaken to see if similar results were obtained when fish were tested in a continuous flow of water in which the concentrations of oxygen and cyanide were kept constant. Periods of survival were measured this way to minimize distortion of results by accumulation of metabolic waste, depletion of oxygen or depletion of poison. Results are summarized as follows: rainbow trout survival in potassium cyanide increased with increase in dissolved oxygen; increase in survival times did not decline as oxygen saturation was approached; and medium survival times of 3.3 minutes or less were normally distributed while those of greater than 13 minutes were log normally distributed. 6 references, 1 figure.

Image analyzing method to evaluate in situ bioluminescence from an obligate anaerobe cultivated under various dissolved oxygen concentrations.

Science.gov (United States)

Ninomiya, Kazuaki; Yamada, Ryuji; Matsumoto, Masami; Fukiya, Satoru; Katayama, Takane; Ogino, Chiaki; Shimizu, Nobuaki

2013-02-01

An image analyzing method was developed to evaluate in situ bioluminescence expression, without exposing the culture sample to the ambient oxygen atmosphere. Using this method, we investigated the effect of dissolved oxygen concentration on bioluminescence from an obligate anaerobe Bifidobacterium longum expressing bacterial luciferase which catalyzes an oxygen-requiring bioluminescent reaction. Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Role of oxygen concentration distribution and microstructure in luminescent properties of laser-irradiated silicon

International Nuclear Information System (INIS)

Zhu, Min; Li, Xiaohong; Li, Guoqiang; Xie, Changxin; Qiu, Rong; Li, Jiawen; Huang, Wenhao

2015-01-01

Graphical abstract: Photoluminescence (PL) of monocrystalline silicon irradiated by femtosecond laser pulses was studied. The visible blue luminescence is observed both from the deionized water and air. The position and shape of emission luminescence peaks in the visible range are same at 330 nm. The PL is confirmed to be not merely induced by the oxygen defects or quantum confinement effects, but is commonly decided by the concentration distribution of SiO x and the depth of the surface microstructure. The PL gets strongest only when depth of the surface microstructure is not deeper and the distribution of the shallow SiO x is more intensive. - Highlights: • Different morphologies and compositions of the surface microstructures are formed. • The SiO x concentration and surface microstructure depth commonly decide the PL. • The PL intensity can be controlled by changing the experimental conditions. - Abstract: We study the photoluminescence (PL) of monocrystalline silicon irradiated by femtosecond laser pulses in different environments (deionized water and air) and energy intensities. The fluorescence spectroscopy measurement results indicate that the visible blue luminescence is observed both from the silicon surfaces ablated in the deionized water and air. The more interesting phenomenon is that the position and shape of the emission luminescence peaks in the visible range are substantially the same at the same excitation wavelength 330 nm. Compared with the granular-like microstructure generated on the silicon surface in air, the smaller and stripe-like microstructure is formed in the deionized water as the field emission scanning electron microscope (FESEM) measures. The results of the energy dispersive spectroscopy (EDS) show that silicon and oxygen is the main elemental composition on laser-induced silicon surfaces, and the oxygen content on the sample surfaces formed in air is nearly four times more than that in the deionized water. The studies confirm

Correlation between near-infrared spectroscopy and magnetic resonance imaging of rat brain oxygenation modulation

International Nuclear Information System (INIS)

Chen Yu; Tailor, Dharmesh R; Intes, Xavier; Chance, Britton

2003-01-01

We measure the tissue oxygen and haemoglobin concentrations in the rat brain during modulation of inhaled oxygen concentration (FiO 2 ), using non-invasive frequency domain near-infrared oximetry. The rise in oxygenated haemoglobin concentration and the decline in deoxygenated haemoglobin concentration are demonstrated in correspondence with the modulation of FiO 2 , which is changed from 20% to 100% in increments of 20%. Furthermore, the tissue oxygenation saturation also shows the corresponding trend and changes ranging from approximately 70% to 90%. The relative changes in deoxygenated haemoglobin concentration are compared to the blood-oxygenation-level-dependent (BOLD) MRI signal recorded during a similar FiO 2 protocol. A linear relationship with high correlation coefficient between the relative changes in the BOLD MRI signal and the NIRS signal is observed

Correlation between near-infrared spectroscopy and magnetic resonance imaging of rat brain oxygenation modulation

Energy Technology Data Exchange (ETDEWEB)

Chen Yu [Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA (United States); Tailor, Dharmesh R [Department of Bioengineering, University of Pennsylvania, Philadelphia, PA (United States); Intes, Xavier [Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA (United States); Chance, Britton [Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA (United States)

2003-02-21

We measure the tissue oxygen and haemoglobin concentrations in the rat brain during modulation of inhaled oxygen concentration (FiO{sub 2}), using non-invasive frequency domain near-infrared oximetry. The rise in oxygenated haemoglobin concentration and the decline in deoxygenated haemoglobin concentration are demonstrated in correspondence with the modulation of FiO{sub 2}, which is changed from 20% to 100% in increments of 20%. Furthermore, the tissue oxygenation saturation also shows the corresponding trend and changes ranging from approximately 70% to 90%. The relative changes in deoxygenated haemoglobin concentration are compared to the blood-oxygenation-level-dependent (BOLD) MRI signal recorded during a similar FiO{sub 2} protocol. A linear relationship with high correlation coefficient between the relative changes in the BOLD MRI signal and the NIRS signal is observed.

Control of oxygen vacancies and Ce+3 concentrations in doped ceria nanoparticles via the selection of lanthanide element

International Nuclear Information System (INIS)

Shehata, N.; Meehan, K.; Hudait, M.; Jain, N.

2012-01-01

The effect of lanthanides that have positive association energies with oxygen vacancies, such as samarium and neodymium, and the elements with negative association energies, such as holmium and erbium, on ionization state of cerium and, consequentially, the oxygen vacancy concentration in doped ceria nanoparticles are investigated in this article. Structural and optical characterizations of the doped and undoped ceria nanoparticles, synthesized using chemical precipitation, are carried out using transmission electron microscopy, X-ray diffractometry, optical absorption spectroscopy, and fluorescence spectroscopy. It is deduced that the negative association energy dopants decrease the conversion of Ce +4 into Ce +3 and, hence, scavenge the oxygen vacancies, evidenced by the observed increase in the allowed direct bandgap, decrease in the integrated fluorescence intensity, and increased the size of doped nanoparticles. The opposite trends are obtained when the positive association dopants are used. It is concluded that the determining factor as to whether a lanthanide dopant in ceria acts as a generator or scavenger of oxygen vacancies in ceria nanoparticles is the sign of the association energy between the element and the oxygen vacancies. The ability to tailor the ionization state of cerium and the oxygen vacancy concentration in ceria has applications in a broad range of fields, which include catalysis, biomedicine, electronics, and environmental sensing.

Oxygen Transport Membranes

Energy Technology Data Exchange (ETDEWEB)

S. Bandopadhyay

2008-08-30

The focus of this research was to develop new membrane materials by synthesizing different compounds and determining their defect structures, crystallographic structures and electrical properties. In addition to measuring electrical conductivity, oxygen vacancy concentration was also evaluated using thermogravimetry, Neutron diffraction and Moessbauer Spectroscopy. The reducing conditions (CO{sub 2}/CO/H{sub 2} gas mixtures with steam) as encountered in a reactor environment can be expected to have significant influence on the mechanical properties of the oxides membranes. Various La based materials with and without Ti were selected as candidate membrane materials for OTM. The maximum electrical conductivity of LSF in air as a function of temperature was achieved at < 600 C and depends on the concentration of Sr (acceptor dopant). Oxygen occupancy in LSF was estimated using Neutron diffractometry and Moessbauer Spectroscopy by measuring magnetic moment changes depending on the Fe{sup 3+} and Fe{sup 4+} ratio. After extensive studies of candidate materials, lanthanum ferrites (LSF and LSFT) were selected as the favored materials for the oxygen transport membrane (OTM). LSF is a very good material for an OTM because of its high electronic and oxygen ionic conductivity if long term stability and mechanical strength are improved. LSFT not only exhibits p-type behavior in the high oxygen activity regime, but also has n-type conduction in reducing atmospheres. Higher concentrations of oxygen vacancies in the low oxygen activity regime may improve the performance of LSFT as an OTM. The hole concentration is related to the difference in the acceptor and donor concentration by the relation p = [Sr'{sub La}]-[Ti{sm_bullet}{sub Fe}]. The chemical formulation predicts that the hole concentration is, p = 0.8-0.45 or 0.35. Experimental measurements indicated that p is about {approx} 0.35. The activation energy of conduction is 0.2 eV which implies that LSCF conducts via the

Impact of oxygen concentration on time to resolution of spontaneous pneumothorax in term infants: a population based cohort study

Science.gov (United States)

2014-01-01

Background Little evidence exists regarding the optimal concentration of oxygen to use in the treatment of term neonates with spontaneous pneumothorax (SP). The practice of using high oxygen concentrations to promote “nitrogen washout” still exists at many centers. The aim of this study was to identify the time to clinical resolution of SP in term neonates treated with high oxygen concentrations (HO: FiO2 ≥ 60%), moderate oxygen concentrations (MO: FiO2 pneumothorax admitted to all neonatal intensive care units in Calgary, Alberta, Canada, within 72 hours of birth between 2006 and 2010. Newborns with congenital and chromosomal anomalies, meconium aspiration, respiratory distress syndrome, and transient tachypnea of newborn, pneumonia, tension pneumothorax requiring thoracocentesis or chest tube drainage or mechanical ventilation before the diagnosis of pneumothorax were excluded. The primary outcome was time to clinical resolution (hours) of SP. A Cox proportional hazards model was developed to assess differences in time to resolution of SP between treatment groups. Results Neonates were classified into three groups based on the treatment received: HO (n = 27), MO (n = 35) and RA (n = 30). There was no significant difference in time to resolution of SP between the three groups, median (range 25th-75th percentile) for HO = 12 hr (8–27), MO = 12 hr (5–24) and RA = 11 hr (4–24) (p = 0.50). A significant difference in time to resolution of SP was also not observed after adjusting for inhaled oxygen concentration [MO (a HR = 1.13, 95% CI 0.54-2.37); RA (a HR = 1.19, 95% CI 0.69-2.05)], gender (a HR = 0.87, 95% CI 0.53-1.43) and ACoRN respiratory score (a HR = 0.7, 95% CI 0.41-1.34). Conclusions Supplemental oxygen use or nitrogen washout was not associated with faster resolution of SP. Infants treated with room air remained stable and did not require supplemental oxygen at any point of their admission. PMID

Electrical property studies of oxygen in Czochralski-grown neutron-transmutation-doped silicon

International Nuclear Information System (INIS)

Cleland, J.W.; Fukuoka, N.

1980-10-01

Electically active oxygen-related donors can be formed in Czochralski (Cz) Si either during crystal growth or during subsequent heat treatment; conventional n- or p-type dopant carrier concentrations are altered if these oxygen donors are present. Neutron transmutation doping (NTD) has been used to introduce a uniform concentration of 31 P in Si. However, oxygen donors can also be formed in NTD Cz Si during the process of annealing to remove NTD radiation damage. In the present experiments, the carrier concentration of Cz and NTD Cz Si samples was determined as a function of the initial dopant, oxygen, and 31 P concentration before and after isothermal or isochronal annealing. It is shown that low temperature (350 to 500 0 C) heat treatment can introduce a significant oxygen donor concentration in Cz Si and in NTD Cz Si that contains radiation-induced lattice defects. Intermediate temperature (550 to 750 0 C) heat treatment, which is intended to remove oxygen donors or lattice defects, can introduce other oxygen donors; annealing above 750 0 C is required to remove any of these oxygen donors. Extended (20 h) high-temperature (1000 to 1200 0 C) annealing can remove oxygen donors and lattice defects, but a significant concentration of oxygen donors can still be introduced by subsequent low temperature heat treatment. These results suggest that oxygen-related donor formation in NTD Cz Si at temperatures below 750 0 C may serve to mask any annealing study of lattice defects. It is concluded that annealing for 30 min at 750 0 C is sufficient to remove radiation damage in NTD Cz Si when the separate effects of oxygen donor formation are included

Corrosion behavior of steels in liquid lead bismuth with low oxygen concentrations

Science.gov (United States)

Kurata, Yuji; Futakawa, Masatoshi; Saito, Shigeru

2008-02-01

Corrosion tests in pots were conducted to elucidate corrosion behavior of various steels in liquid lead-bismuth for 3000 h under the condition of an oxygen concentration of 5 × 10 -8 wt% at 450 °C and an oxygen concentration of 3 × 10 -9 wt% at 550 °C, respectively. Significant corrosion was not observed at 450 °C for ferritic/martensitic steels, F82H, Mod.9Cr-1Mo steel, 410SS, 430SS except 2.25Cr-1Mo steel. Pb-Bi penetration into steels and dissolution of elements into Pb-Bi were severe at 550 °C even for ferritic/martensitic steels. Typical dissolution attack occurred for pure iron both at 550 °C without surface Fe 3O 4 and at 450 °C with a thin Fe 3O 4 film. Ferritization due to dissolution of Ni and Cr, and Pb-Bi penetration were recognized for austenitic stainless steels, 316SS and 14Cr-16Ni-2Mo steel at both temperatures of 450 °C and 550 °C. The phenomena were mitigated for 18Cr-20Ni-5Si steel. In some cases oxide films could not be a corrosion barrier in liquid lead-bismuth.

Effects of fulvic acid concentration and origin on photodegradation of polycyclic aromatic hydrocarbons in aqueous solution: Importance of active oxygen

International Nuclear Information System (INIS)

Xia Xinghui; Li Gongchen; Yang Zhifeng; Chen Yumin; Huang, Gordon H.

2009-01-01

With an Xe arc lamp house as simulated sunlight, the influences of fulvic acid (FA) concentration and origins on photodegradation of acenaphthene, fluorine, phenanthrene, fluoranthene and pyrene in aqueous solution have been studied. Similar effects of FAs, collected from five places around China, on polycyclic aromatic hydrocarbon (PAH) photodegradation have been observed. Active oxygen was of significance in PAH photodegradation with the presence of FAs. For systems with 1.25 mg L -1 FAs, the contributions of ·OH to PAH photodegradation rates were from 33% to 69%. FAs had two opposite effects, i.e., stimulating the generation of active oxygen and advancing PAH photodegradation; competing with PAHs for energy and photons and restraining PAH photodegradation. Generally, photodegradation rates of the 5 PAHs decreased with the increase of FAs concentration; except fluoranthene and pyrene were advanced in solutions with low FA concentration. The influences of FA concentration on PAH photodegradation were more significant than FA origin. - Influences of fulvic acid (FA) concentration on PAH photodegradation were more significant than FA origin, and active oxygen played an important role in PAH photodegradation

Ion measurements in premixed methane-oxygen flames

KAUST Repository

Alquaity, Awad

2014-07-25

Ions are formed as a result of chemi-ionization processes in combustion systems. Recently, there has been an increasing interest in understanding flame ion chemistry due to the possible application of external electric fields to reduce emissions and improve combustion efficiency by active control of combustion process. In order to predict the effect of external electric fields on combustion plasma, it is critical to gain a good understanding of the flame ion chemistry. In this work, a Molecular Beam Mass Spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane-oxygen-argon burner-stabilized flames. Lean, stoichiometric and rich flames at atmospheric pressure are used to study the dependence of ion chemistry on equivalence ratio of premixed flames. The relative ion concentration profiles are compared qualitatively with previous methane-oxygen studies and show good agreement. The relative ion concentration data obtained in the present study can be used to validate and improve ion chemistry models for methane-oxygen flames.

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

Science.gov (United States)

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.

Oxygen discharge and post-discharge kinetics experiments and modeling for the electric oxygen-iodine laser system.

Science.gov (United States)

Palla, A D; Zimmerman, J W; Woodard, B S; Carroll, D L; Verdeyen, J T; Lim, T C; Solomon, W C

2007-07-26

Laser oscillation at 1315 nm on the I(2P1/2)-->I(2P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1Delta) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels of complexity to the singlet oxygen generator (SOG) kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. The advanced model BLAZE-IV has been introduced to study the energy-transfer laser system dynamics and kinetics. Levels of singlet oxygen, oxygen atoms, and ozone are measured experimentally and compared with calculations. The new BLAZE-IV model is in reasonable agreement with O3, O atom, and gas temperature measurements but is under-predicting the increase in O2(a1Delta) concentration resulting from the presence of NO in the discharge and under-predicting the O2(b1Sigma) concentrations. A key conclusion is that the removal of oxygen atoms by NOX species leads to a significant increase in O2(a1Delta) concentrations downstream of the discharge in part via a recycling process; however, there are still some important processes related to the NOX discharge kinetics that are missing from the present modeling. Further, the removal of oxygen atoms dramatically inhibits the production of ozone in the downstream kinetics.

THE EFFECT OF THE STATIC RELATIVE STRENGTH ON THE MAXIMUM RELATIVE RECEIVING OF OXYGEN

Directory of Open Access Journals (Sweden)

Abdulla Elezi

2011-09-01

Full Text Available Based on research on the sample of 263 students of age- 18 years, and used batteries of 9 tests for evaluation of the static relative strength and the criterion variable- maximum relative receiving of oxygen (VO2 ml / kg / min based on the Astrand test ,and on regression analysis to determine the influence of the static relative strength on the criterion variable maximum relative oxygen receiving, can be generally concluded that from 9 predictor variables statistically significant partial effect have 2variables. In hierarchical order, they are: the variable of static relative leg strength - endurance of the fingers (the angle of the lower leg and thigh 900 (SRL2 which arithmetic mean is 25.04 seconds and variable ctatic relative strength of arms and shoulders – push-up endurance in the balance beam (angle of the forearm and upper arm 900 ( SRA2 with arithmetic mean of 17.75 seconds. From the statistically influential significant predictor variables on the criterion variable one is from the static relative leg strength (SRL2 and the other is from the static relative strength of arm and shoulder area (SRA2. With the analysis of these relations we can conclude that the isometric contractions of the four headed thigh muscle and the isometric contractions of the three headed upper arm muscle are predominantly responsible for the successful execution of doing actions on a bicycle ergometer and not on the maximum relative receiving of oxygen.

Irradiation of mammalian cells in the presence of diamide and low concentrations of oxygen at conventional and at ultrahigh dose rates

International Nuclear Information System (INIS)

Clark, E.P.; Michaels, H.B.; Peterson, E.C.; Epp, E.R.

1983-01-01

The response of cultured CHO cells to ultrahigh-dose-radiation (approx.10 9 Gy/sec) has been previously studied extensively using the thin-layer cell-handling technique developed in this laboratory. When the cells are equilibrated with a low concentration of oxygen, e.g., 0.44% O 2 , a breaking survival curve, due to radiolytic depletion of the oxygen, is observed. Hypoxic cells irradiated in the presence of the nitroimidazoles (e.g., misonidazole) are sensitized at ultrahigh dose rates in a dose-modifying manner, similar to that observed at conventional dose rates. These radiosensitizer compounds, if present in cells equilibrated with a low concentration of oxygen, prevent the breaking behavior of the survival curve, an observation believed to be due to the sensitizer interfering with the oxygen depletion process, leaving oxygen free to sensitize. Such experiments have recently been extended to studies with diamide, which, unlike the other sensitizers tested, acts primarily as a shoulder-modifying rather than a dose-modifying agent in hypoxic mammalian cells. These data indicate that diamide is active as a sensitizer at ultrahigh dose rates in a manner similar to that observed at conventional dose rates, and does modify the shape of the breaking survival curve observed with low concentrations of oxygen

Quantitative relations between chemical oxygen demand concentration and its influence factors in the sluice-controlled river reaches of Shaying River, China.

Science.gov (United States)

Dou, Ming; Li, Guiqiu; Li, Congying

2015-01-01

Recent research on the effects of dam and sluice construction on the water environment has attracted extensive attention from academia and governments alike. Because the operation of sluices greatly alters environmental factors such as water flow and sediment load, the water quality in sluice-controlled river reaches (SCRRs) undergoes complex changes compared with those in normal reaches. This work used river reaches near the Huaidian Sluice in Shaying River of China as a case study to analyse the effects of sluice operation on water quality evolution in SCRRs. The most influential factors affecting the rate of change in chemical oxygen demand (COD) concentration in SCRRs were identified through water quality monitoring experiments performed under various modes of sluice operation and by applying a statistical method 'partial correlation analysis'. Then, a hydrodynamic model incorporating sluice operation and a water quality transport and transform model incorporating the release of endogenous loads were developed. Using these two models, the processes of temporal and spatial change of COD concentrations in the SCRRs were simulated under various scenarios designed to represent the dominant factors of influence. Finally, the simulation results were used to develop empirical relationships between the rate of change in COD concentrations and the dominant factors of influence. The results reveal that three factors, i.e., water inflow concentration, gate opening size, and gate opening number, are the dominant factors of influence, and there are logarithmic relationships between the rate of change in COD concentration in the SCRRs and these factors.

Quantitative spatially resolved measurement of tissue chromophore concentrations using photoacoustic spectroscopy: application to the measurement of blood oxygenation and haemoglobin concentration

Science.gov (United States)

Laufer, Jan; Delpy, Dave; Elwell, Clare; Beard, Paul

2007-01-01

A new approach based on pulsed photoacoustic spectroscopy for non-invasively quantifying tissue chromophore concentrations with high spatial resolution has been developed. The technique is applicable to the quantification of tissue chromophores such as oxyhaemoglobin (HbO2) and deoxyhaemoglobin (HHb) for the measurement of physiological parameters such as blood oxygen saturation (SO2) and total haemoglobin concentration. It can also be used to quantify the local accumulation of targeted contrast agents used in photoacoustic molecular imaging. The technique employs a model-based inversion scheme to recover the chromophore concentrations from photoacoustic measurements. This comprises a numerical forward model of the detected time-dependent photoacoustic signal that incorporates a multiwavelength diffusion-based finite element light propagation model to describe the light transport and a time-domain acoustic model to describe the generation, propagation and detection of the photoacoustic wave. The forward model is then inverted by iteratively fitting it to measurements of photoacoustic signals acquired at different wavelengths to recover the chromophore concentrations. To validate this approach, photoacoustic signals were generated in a tissue phantom using nanosecond laser pulses between 740 nm and 1040 nm. The tissue phantom comprised a suspension of intralipid, blood and a near-infrared dye in which three tubes were immersed. Blood at physiological haemoglobin concentrations and oxygen saturation levels ranging from 2% to 100% was circulated through the tubes. The signal amplitude from different temporal sections of the detected photoacoustic waveforms was plotted as a function of wavelength and the forward model fitted to these data to recover the concentrations of HbO2 and HHb, total haemoglobin concentration and SO2. The performance was found to compare favourably to that of a laboratory CO-oximeter with measurement resolutions of ±3.8 g l-1 (±58 µM) and ±4

Quantitative spatially resolved measurement of tissue chromophore concentrations using photoacoustic spectroscopy: application to the measurement of blood oxygenation and haemoglobin concentration

Energy Technology Data Exchange (ETDEWEB)

Laufer, Jan; Delpy, Dave; Elwell, Clare; Beard, Paul [Department of Medical Physics and Bioengineering, University College London, Malet Place Engineering Building, London WC1E 6BT (United Kingdom)

2007-01-07

A new approach based on pulsed photoacoustic spectroscopy for non-invasively quantifying tissue chromophore concentrations with high spatial resolution has been developed. The technique is applicable to the quantification of tissue chromophores such as oxyhaemoglobin (HbO{sub 2}) and deoxyhaemoglobin (HHb) for the measurement of physiological parameters such as blood oxygen saturation (SO{sub 2}) and total haemoglobin concentration. It can also be used to quantify the local accumulation of targeted contrast agents used in photoacoustic molecular imaging. The technique employs a model-based inversion scheme to recover the chromophore concentrations from photoacoustic measurements. This comprises a numerical forward model of the detected time-dependent photoacoustic signal that incorporates a multiwavelength diffusion-based finite element light propagation model to describe the light transport and a time-domain acoustic model to describe the generation, propagation and detection of the photoacoustic wave. The forward model is then inverted by iteratively fitting it to measurements of photoacoustic signals acquired at different wavelengths to recover the chromophore concentrations. To validate this approach, photoacoustic signals were generated in a tissue phantom using nanosecond laser pulses between 740 nm and 1040 nm. The tissue phantom comprised a suspension of intralipid, blood and a near-infrared dye in which three tubes were immersed. Blood at physiological haemoglobin concentrations and oxygen saturation levels ranging from 2% to 100% was circulated through the tubes. The signal amplitude from different temporal sections of the detected photoacoustic waveforms was plotted as a function of wavelength and the forward model fitted to these data to recover the concentrations of HbO{sub 2} and HHb, total haemoglobin concentration and SO{sub 2}. The performance was found to compare favourably to that of a laboratory CO-oximeter with measurement resolutions of {+-}3

Quantitative spatially resolved measurement of tissue chromophore concentrations using photoacoustic spectroscopy: application to the measurement of blood oxygenation and haemoglobin concentration

International Nuclear Information System (INIS)

Laufer, Jan; Delpy, Dave; Elwell, Clare; Beard, Paul

2007-01-01

A new approach based on pulsed photoacoustic spectroscopy for non-invasively quantifying tissue chromophore concentrations with high spatial resolution has been developed. The technique is applicable to the quantification of tissue chromophores such as oxyhaemoglobin (HbO 2 ) and deoxyhaemoglobin (HHb) for the measurement of physiological parameters such as blood oxygen saturation (SO 2 ) and total haemoglobin concentration. It can also be used to quantify the local accumulation of targeted contrast agents used in photoacoustic molecular imaging. The technique employs a model-based inversion scheme to recover the chromophore concentrations from photoacoustic measurements. This comprises a numerical forward model of the detected time-dependent photoacoustic signal that incorporates a multiwavelength diffusion-based finite element light propagation model to describe the light transport and a time-domain acoustic model to describe the generation, propagation and detection of the photoacoustic wave. The forward model is then inverted by iteratively fitting it to measurements of photoacoustic signals acquired at different wavelengths to recover the chromophore concentrations. To validate this approach, photoacoustic signals were generated in a tissue phantom using nanosecond laser pulses between 740 nm and 1040 nm. The tissue phantom comprised a suspension of intralipid, blood and a near-infrared dye in which three tubes were immersed. Blood at physiological haemoglobin concentrations and oxygen saturation levels ranging from 2% to 100% was circulated through the tubes. The signal amplitude from different temporal sections of the detected photoacoustic waveforms was plotted as a function of wavelength and the forward model fitted to these data to recover the concentrations of HbO 2 and HHb, total haemoglobin concentration and SO 2 . The performance was found to compare favourably to that of a laboratory CO-oximeter with measurement resolutions of ±3.8 g l -1 (±58 �

Impact of oxygen concentration on yields of DNA damages caused by ionizing radiation

Czech Academy of Sciences Publication Activity Database

Štěpán, Václav; Davídková, Marie

2008-01-01

Roč. 101, 012015 (2008), s. 1-4 ISSN 1742-6588. [Radiation Damage in Biomolecular Systems, RADAM'07. Dublin, 19.06.2007-22.06.2007] R&D Projects: GA ČR(CZ) GD202/05/H031; GA ČR GA202/05/2728 Institutional research plan: CEZ:AV0Z10480505 Keywords : radiation damage to DNA * oxygen concentration * theoretical modeling Subject RIV: BO - Biophysics

Removal method of fluorescent dyes as pretreatment for measurement of major ion concentrations and hydrogen and oxygen isotopic ratios

International Nuclear Information System (INIS)

Nakata, Kotaro; Hasegawa, Takuma; Kashiwaya, Koki; Kodama, Hiroki; Miyajima, Tohru

2011-01-01

The major ion concentration and isotope ratio of hydrogen and oxygen can provide important information for migration of groundwater. Sometimes, quantitative estimation of these chemical and isotopic characteristics of solution is necessary for groundwater containing fluorescent dyes, which are used in drilling borehole and tracer experiments. However, sometimes correct estimation is disturbed by dyes and they become a cause of troubles for measurement equipments. Thus development of method to remove dyes is required so that the characteristics of groundwater can be estimated without the negative effect of dyes on measurement or equipments. In this study, removal of four representative dyes (Uranin, Eosin, Naphthalenesulfonic acid sodium(NAP) and Amino G acid potassium salt (AG)) was investigated. Uranin and Eosin were found to be removed by non-ionic synthetic resin: HP2MG. 99.99% of the dyes were removed from initial solutions containing dyes with 10 mg/L after contact with resin, while the contact had little effect on ion concentrations and oxygen and hydrogen isotope ratios. Thus the chemical and isotopic characteristics of groundwater samples containing Uranin and Eosin can be obtained by using the HP2MG resin. On the other hand, the NAP and AG were found to be difficult to remove by the HP2MG resin but they were able to be removed by anion exchange resin (Dowex 1x8). Though contact of solution with Dowex 1x8 did not affect cation concentrations and hydrogen and oxygen isotope ratios, anion concentrations were changed by the contact. Therefore the Dowex 1x8 is only applicable to estimation of the cation concentrations and isotope ratio of hydrogen and oxygen. When both anion and cation concentrations from the samples were necessary, Uranin or Eosin were recommended as a tracer in drilling or tracer experiments. (author)

Oxygen-related 1-platinum defects in silicon: An electron paramagnetic resonance study

Science.gov (United States)

Juda, U.; Scheerer, O.; Höhne, M.; Riemann, H.; Schilling, H.-J.; Donecker, J.; Gerhardt, A.

1996-09-01

A monoclinic 1-platinum defect recently detected was investigated more thoroughly by electron paramagnetic resonance (EPR). The defect is one of the dominating defects in platinum doped silicon. With a perfect reproducibility it is observed in samples prepared from n-type silicon as well as from p-type silicon, in float zone (FZ) silicon as well as in Czochralski (Cz) silicon. Its concentration varies with the conditions of preparation and nearly reaches that of isolated substitutional platinum in Cz silicon annealed for 2 h at 540 °C after quenching from the temperature of platinum diffusion. Because of its concentration which in Cz-Si exceeds that in FZ-Si the defect is assumed to be oxygen-related though a hyperfine structure with 17O could not be resolved. The defect causes a level close to the valence band. This is concluded from variations of the Fermi level and from a discussion of the spin Hamiltonian parameters. In photo-EPR experiments the defect is coupled to recently detected acceptorlike self-interstitial related defects (SIRDs); their level position turns out to be near-midgap. These defects belong to the lifetime limiting defects in Pt-doped Si.

BaSi2 formation mechanism in thermally evaporated films and its application to reducing oxygen impurity concentration

Science.gov (United States)

Hara, Kosuke O.; Yamamoto, Chiaya; Yamanaka, Junji; Arimoto, Keisuke; Nakagawa, Kiyokazu; Usami, Noritaka

2018-04-01

Thermal evaporation is a simple and rapid method to fabricate semiconducting BaSi2 films. In this study, to elucidate the BaSi2 formation mechanism, the microstructure of a BaSi2 epitaxial film fabricated by thermal evaporation has been investigated by transmission electron microscopy. The BaSi2 film is found to consist of three layers with different microstructural characteristics, which is well explained by assuming two stages of film deposition. In the first stage, BaSi2 forms through the diffusion of Ba atoms from the deposited Ba-rich film to the Si substrate while in the second stage, the mutual diffusion of Ba and Si atoms in the film leads to BaSi2 formation. On the basis of the BaSi2 formation mechanism, two issues are addressed. One is the as-yet unclarified reason for epitaxial growth. It is found important to quickly form BaSi2 in the first stage for the epitaxial growth of upper layers. The other issue is the high oxygen concentration in BaSi2 films around the BaSi2-Si interface. Two routes of oxygen incorporation, i.e., oxidation of the Si substrate surface and initially deposited Ba-rich layer by the residual gas, are identified. On the basis of this knowledge, oxygen concentration is decreased by reducing the holding time of the substrate at high temperatures and by premelting of the source. In addition, X-ray diffraction results show that the decrease in oxygen concentration can lead to an increased proportion of a-axis-oriented grains.

A Solar Powered, Ceramic Oxygen Concentrator

Data.gov (United States)

National Aeronautics and Space Administration — Childhood pneumonia, which is treated with oxygen therapy, is a leading cause of death in children. Many children in developing countries lack access to medical...

Radiation accelerated formation of oxygen and carbon related complexes in silicon

International Nuclear Information System (INIS)

Lazrak, A.; Magnea, N.; Pautrat, J.L.

1984-06-01

During the pulling of silicon monocrystals by the Czochralsky method, oxygen is incorporated into the lattice. It is known from early works that low temperature annealings (400-1000 0 C) make this oxygen to precipitate and a number of different defects to be generated. In order to check whether the fast diffusivity of an oxygen silicon interstitial complex has to be taken in consideration it was interesting to examinate the possible role of radiation damage on the formation of oxygen related defects. Experimental results of an experiment are presented and discussed

Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

International Nuclear Information System (INIS)

Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V.

2001-01-01

The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E c ) and at 415 K (0.9 below E c ); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E c known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E c is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species

Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

Science.gov (United States)

Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S. V.

2001-10-01

The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below Ec) and at 415 K (0.9 below Ec); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below Ec known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below Ec is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species.

Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

International Nuclear Information System (INIS)

Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V.

2004-01-01

The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E c ) and at 415 K (0.9 below E c ); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E c known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E c is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species. (author)

Determination of optical properties, drug concentration, and tissue oxygenation in human pleural tissue before and after Photofrin-mediated photodynamic therapy

Science.gov (United States)

Ong, Yi Hong; Padawer-Curry, Jonah; Finlay, Jarod C.; Kim, Michele M.; Dimofte, Andreea; Cengel, Keith; Zhu, Timothy C.

2018-02-01

PDT efficacy depends on the concentration of photosensitizer, oxygen, and light delivery in patient tissues. In this study, we measure the in-vivo distribution of important dosimetric parameters, namely the tissue optical properties (absorption μa (λ) and scattering μs ' (λ) coefficients), photofrin concentration (cphotofrin), blood oxygen saturation (%StO2), and total hemoglobin concentration (THC), before and after PDT. We characterize the inter- and intra-patient heterogeneity of these quantities and explore how these properties change as a result of PDT treatment. The result suggests the need for real-time dosimetry during PDT to optimize the treatment condition depending on the optical and physiological properties.

About the 'enlightenment' of nonideal hydrogen-oxygen plasma at a electron concentration Ne19 cm-3

International Nuclear Information System (INIS)

Fedorovich, O.A.

2013-01-01

The results of experimental determination of the emissivity of the hydrogen-oxygen plasma pulsed discharge in water and their comparison with calculations. It is shown that when concentrations nonideal plasma N e >3 centre dot 10 18 cm -3 , is observed 'enlightenment' of plasma. The reduction of a emitting ability . can be more order in the N e =3 centre dot 10 19 cm -3 and increases with increasing electron concentration.

[Domiciliary oxygen therapy].

Science.gov (United States)

Abdel Kafi, S

2010-09-01

In Belgium, oxygen therapy is becoming more and more accessible. When oxygen is needed for short periods or for special indications as palliative care, an agreement between mutual insurance companies and pharmacists allows the practitioner the home installation of gazeous oxygen cylinder or of oxygen concentrator. When long term oxygen therapy (LTOT) is indicated for patients with respiratory insufficiency, the pneumologist must first ask the INAMI the authorization to install one of the following modalities: oxygen concentrator with or without demand oxygen delivery cylinder and liquid oxygen. The goal of LTOT is to increase survival and quality of life. The principal and well accepted indication for LTOT is severe hypoxemia. The beneficial effects of oxygen therapy limited at night or on exertion are controversial. In order to increase patient's autonomy, oxygen can be prescribed for ambulation, respecting prescription's rules. At each step of oxygen therapy implementing (indication, choice of the device and follow-up) the patient under oxygen may benefit from a joint approach between the general practitioner and the chest specialist.

Effect of reduced light and low oxygen concentration on germination, growth and establishment of some plants

DEFF Research Database (Denmark)

Yasin, Muhammad

Many abiotic factors effect plants germination, growth, and development. This Ph.D. study elucidates the effect of reduced light, low oxygen and seed dormancy on germination and growth of some weed species, field crops and vegetables. One study describes the growth and developmental responses...... of some common, invasive and rare weed species to reduced light levels in greenhouse experiments. The seed germination response of some weed species, field crops, and vegetables to different oxygen concentrations was also quantified in the laboratory experiments. The effect of east-west (EW) and north...

Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V. E-mail: svb@physics.unipune.ernet.in

2001-10-01

The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E{sub c}) and at 415 K (0.9 below E{sub c}); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E{sub c} known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E{sub c} is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species.

The effects of oxygen level and glucose concentration on the metabolism of porcine TMJ disc cells.

Science.gov (United States)

Cisewski, S E; Zhang, L; Kuo, J; Wright, G J; Wu, Y; Kern, M J; Yao, H

2015-10-01

To determine the combined effect of oxygen level and glucose concentration on cell viability, ATP production, and matrix synthesis of temporomandibular joint (TMJ) disc cells. TMJ disc cells were isolated from pigs aged 6-8 months and cultured in a monolayer. Cell cultures were preconditioned for 48 h with 0, 1.5, 5, or 25 mM glucose DMEM under 1%, 5%, 10%, or 21% O2 level, respectively. The cell viability was measured using the WST-1 assay. ATP production was determined using the Luciferin-Luciferase assay. Collagen and proteoglycan synthesis were determined by measuring the incorporation of [2, 3-(3)H] proline and [(35)S] sulfate into the cells, respectively. TMJ disc cell viability significantly decreased (P oxygen levels significantly increased viability (P oxygen levels significantly reduced ATP production (P oxygen was significant in regards to cell viability (P oxygen are important, glucose is the limiting nutrient for TMJ disc cell survival. At low oxygen levels, the production of ATP, collagen, and proteoglycan are severely inhibited. These results suggest that steeper nutrient gradients may exist in the TMJ disc and it may be vulnerable to pathological events that impede nutrient supply. Copyright © 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

The Oxygen Paradox, the French Paradox, and age-related diseases.

Science.gov (United States)

Davies, Joanna M S; Cillard, Josiane; Friguet, Bertrand; Cadenas, Enrique; Cadet, Jean; Cayce, Rachael; Fishmann, Andrew; Liao, David; Bulteau, Anne-Laure; Derbré, Frédéric; Rébillard, Amélie; Burstein, Steven; Hirsch, Etienne; Kloner, Robert A; Jakowec, Michael; Petzinger, Giselle; Sauce, Delphine; Sennlaub, Florian; Limon, Isabelle; Ursini, Fulvio; Maiorino, Matilde; Economides, Christina; Pike, Christian J; Cohen, Pinchas; Salvayre, Anne Negre; Halliday, Matthew R; Lundquist, Adam J; Jakowec, Nicolaus A; Mechta-Grigoriou, Fatima; Mericskay, Mathias; Mariani, Jean; Li, Zhenlin; Huang, David; Grant, Ellsworth; Forman, Henry J; Finch, Caleb E; Sun, Patrick Y; Pomatto, Laura C D; Agbulut, Onnik; Warburton, David; Neri, Christian; Rouis, Mustapha; Cillard, Pierre; Capeau, Jacqueline; Rosenbaum, Jean; Davies, Kelvin J A

2017-12-01

transduction pathways to increase expression of protective genes, by mechanisms that are completely different from those by which the same agent induces toxicity at high concentrations. In this review, we explore the influences and effects of paradoxes such as the Oxygen Paradox and the French Paradox on the etiology, progression, and outcomes of many of the major human age-related diseases, as well as the basic biological phenomenon of ageing itself.

Thermodynamics of oxygen in solid solution in vanadium and niobium--vanadium alloys

International Nuclear Information System (INIS)

Steckel, G.L.

1977-01-01

A thermodynamic study was made of the vanadium-oxygen and niobium-vanadium-oxygen systems utilizing the solid state galvanic cell technique. Investigations were made with a ThO 2 /Y 2 O 3 electrolyte over the temperature ranges 700 to 1200 0 C (973 to 1473 K) for the binary system and 650 to 1150 0 C (923 to 1423 K) for the ternary system. The activity of oxygen in vanadium obeys Henry's law for the temperatures of this investigation for concentrations up to 3.2 at. percent oxygen. For higher concentrations the activity coefficient shows positive deviations from Henry's law. The terminal solubility of oxygen in vanadium was determined. The activity of oxygen in Nb--V alloys obeys Henry's law for the temperatures of this study for oxygen concentrations less than approximately 2 at. percent. For certain Nb/V ratios Henry's law is obeyed for concentrations as high as 6.5 at. percent oxygen. First order entropy and enthalpy interaction coefficients have been determined to describe the effect on the oxygen activity of niobium additions to vanadium-rich alloys with dilute oxygen concentrations. Niobium causes relatively small decreases in the oxygen activity of V-rich alloys and increases the oxygen solubility limit. Vanadium additions to Nb-rich alloys also increases the oxygen solubility and causes substantial decreases in the dilute solution oxygen activities. The change in the thermodynamic properties when molecular oxygen dissolves in vanadium and niobium--vanadium alloys and the equilibrium oxygen pressure over the binary and ternary systems were also determined

Cytotoxicity of InP/ZnS quantum dots related to reactive oxygen species generation

Science.gov (United States)

Chibli, Hicham; Carlini, Lina; Park, Soonhyang; Dimitrijevic, Nada M.; Nadeau, Jay L.

2011-06-01

Indium phosphide (InP) quantum dots (QDs) have emerged as a presumably less hazardous alternative to cadmium-based particles, but their cytotoxicity has not been well examined. Although their constituent elements are of very low toxicity to cells in culture, they nonetheless exhibit phototoxicity related to generation of reactive oxygen species by excited electrons and/or holes interacting with water and molecular oxygen. Using spin-trap electron paramagnetic resonance (EPR) spectroscopy and reporter assays, we find a considerable amount of superoxide and a small amount of hydroxyl radical formed under visible illumination of biocompatible InP QDs with a single ZnS shell, comparable to what is seen with CdTe. A double thickness shell reduces the reactive oxygen species concentration approximately two-fold. Survival assays in five cell lines correspondingly indicate a distinct reduction in toxicity with the double-shell InP QDs. Toxicity varies significantly across cell lines according to the efficiency of uptake, being overall significantly less than what is seen with CdTe or CdSe/ZnS. This indicates that InP QDs are a useful alternative to cadmium-containing QDs, while remaining capable of electron-transfer processes that may be undesirable or which may be exploited for photosensitization applications.

Cytotoxicity of InP/ZnS quantum dots related to reactive oxygen species generation.

Energy Technology Data Exchange (ETDEWEB)

Chibli, H.; Carlini, L.; Park, S.; Dimitrijevic, N. M.; Nadeau, J. L. (Center for Nanoscale Materials); ( CSE); (McGill Univ.)

2011-01-01

Indium phosphide (InP) quantum dots (QDs) have emerged as a presumably less hazardous alternative to cadmium-based particles, but their cytotoxicity has not been well examined. Although their constituent elements are of very low toxicity to cells in culture, they nonetheless exhibit phototoxicity related to generation of reactive oxygen species by excited electrons and/or holes interacting with water and molecular oxygen. Using spin-trap electron paramagnetic resonance (EPR) spectroscopy and reporter assays, we find a considerable amount of superoxide and a small amount of hydroxyl radical formed under visible illumination of biocompatible InP QDs with a single ZnS shell, comparable to what is seen with CdTe. A double thickness shell reduces the reactive oxygen species concentration approximately two-fold. Survival assays in five cell lines correspondingly indicate a distinct reduction in toxicity with the double-shell InP QDs. Toxicity varies significantly across cell lines according to the efficiency of uptake, being overall significantly less than what is seen with CdTe or CdSe/ZnS. This indicates that InP QDs are a useful alternative to cadmium-containing QDs, while remaining capable of electron-transfer processes that may be undesirable or which may be exploited for photosensitization applications.

Oxygen enhancement of groundwater using an oxygen releasing compound in a funnel-and-gate system

Energy Technology Data Exchange (ETDEWEB)

Thomas, D G

1994-01-01

ORC is a fine white MgO[sub 2] powder treated with a patented process so that a slow, relatively steady release of oxygen occurs when the powder is in contact with water. Recent work suggests ORC could potentially be used to increase the dissolved oxygen (DO) concentration of ground water, thereby enhancing the biodegradation of dissolved phase contaminants such as benzene and toluene from gasoline spills. Field and laboratory tests were performed to evaluate the oxygen release characteristics of ORC when mixed with filter sand and exposed to groundwater from an aquifer in Ontario. Quasi steady state oxygen release rates of 0.013-0.030 and 0.030 mg O[sub 2]/d per g of ORC were determined from the column and field tests respectively. The column tests indicated that steady state oxygen release conditions from the ORC required ca 90 d after initial contact with water, but field data indicated that oxygen release rate may continue to decrease. Falling head permeameter tests indicated that a maximum drop in hydraulic conductivity occurred within the first 48 h of exposure of ORC to water. Both laboratory and field studies indicated that ORC-contacted water increased in pH. Field studies further suggested an inverse correlation between pH increases and the ability of ORC to enhance DO concentration of ground water. The use of ORC in a funnel-and-gate scheme appears to be an effective means of increasing the DO concentration in ground water, thereby stimulating the in-situ bioremediation of many organic contaminants. 30 refs., 17 figs., 12 tabs.

Investigation of oxygen distribution in HTSC-insulator in film structures on light ion beam

International Nuclear Information System (INIS)

Verbitskaya, E.M.; Grekhov, I.V.; Eremin, V.K.; Konnikov, S.G.; Linijchuk, I.A.; Razumov, S.V.; Semchinova, O.K.; Strokan, N.B.; Dyumin, A.N.; Lebedev, V.M.

1992-01-01

Use of nuclear reaction method on accelerated ions for profiling of oxygen concentration in thin-film HTSC structures is considered. Reaction on 16 O(d, α) 14 N deuterons, in course of which ∼ 2.6 MeV α-particles are generated, is used. Detected in experiment 2.0-2.6 MeV α-particle spectrum permits to recognstruct oxygen concentration profile in sample depth. Results obtained on YBa 2 Cu 3 O 7-δ and Y 2 BaCuO 5 film om MgO sunstrates, relating to the case of both uniform and nonuniform oxygen distribution, are presented. Resolution in the depth ∼ 200 A and accuracy of concentration measurement (relatively MgO substrate) of several percents are attained during oxygen profiling

Fast removal of oxygen from biological systems

International Nuclear Information System (INIS)

Dewey, D.L.; Michael, B.D.

1975-01-01

Reference is made to the fact that if radiation is given at a high enough dose rate, the biological effect of oxygen is less than at low dose rates. Examples are given of 'break-point' experiments showing the effect. It is stated that the rapid removal of a substance by radiation is not confined to oxygen: the only criterion required to demonstrate the effect is that the chemical causes a measurable sensitization or protection at a concentration small enough so that it can be depleted at a relatively low dose of radiation. Sufficient confidence is now placed in the effect that it can be used the other way round; that is, to measure the position of the break-point and from this measurement determine the oxygen concentration at the target site at the instant before irradiation. Examples are given of the use of the high dose rate technique for measuring the oxygen concentration inside mammalian cells (Chinese hamster cells). The effects of partial pressures of inert gases, and the effect of elevated gas pressures, are discussed. (U.K.)

Oxygen: the two-faced elixir of life.

Science.gov (United States)

Biddle, Chuck

2008-02-01

Take a moment and consider our planet without oxygen. Imagine the earth some 2.5 billion years ago when oxygen first appeared as a waste product of early anaerobes. Oxygen, as we know it today, is essential for life. Abundant and relatively inexpensive to manufacture, oxygen has widespread use in industry and healthcare. Anesthesia providers routinely administer oxygen in concentrations exceeding that in ambient air to ensure clinical safety and to offset the predictable sequelae associated with patient, drug-related, and procedural factors. Understanding the history of this unique element is critical in evaluating the often contentious body of contemporary research that has illuminated its efficacy (as elixir) and its attendant complications (its "two-faced" nature). Of particular interest is its role in free radical formation as etiogenic in developing complications. Oxygen is a mainstay in the perioperative management of patients, but its administration should be guided by thoughtful and rational goal-directed outcomes to maximize efficacy and minimize complications associated with its use.

Local Cytokine Concentrations and Oxygen Pressure Are Related to Maturation of the Collateral Circulation in Humans

NARCIS (Netherlands)

Schirmer, Stephan H.; van Royen, Niels; Moerland, Perry D.; Fledderus, Joost O.; Henriques, José P.; van der Schaaf, René J.; Vis, Marije M.; Baan, Jan; Koch, Karel T.; Horrevoets, Anton J. G.; Hoefer, Imo E.; Piek, Jan J.

2009-01-01

Objectives Our aim was to determine cytokine and oxygen gradients over the collateral circulation in humans. Background The molecular background of the maturation of the collateral circulation in response to coronary narrowing is poorly understood in humans, partly because of difficulties in

Radiosensitization of CHO cells by the combination of glutathione depletion and low concentrations of oxygen: The effect of different levels of GSH depletion

International Nuclear Information System (INIS)

Clark, E.P.; Epp, E.R.; Zachgo, E.A.; Biaglow, J.E.

1984-01-01

Recently, the authors have examined the effect of GSH depletion by BSO on CHO cells equilibrated with oxygen at various concentrations (0.05-4.0%) and irradiated with 50 kVp x-rays. This is of interest because of the uncertain radiosensitizing effect GSH depletion may have on cells equilibrated with low oxygen concentrations. GSH depletion (0.1 mM BSO/24 hrs reduced [GSH] ≅ 10% of control) enhanced the radiosensitizing action of moderate (0.4-4.0%) concentrations of oxygen, i.e., GSH depletion reduced the [O/sub 2/] necessary to achieve an equivalent ER by ≅ 2-3 fold. However, GSH depletion was much more effective as a rediosensitizer when cells were equilibrated with low (<0.4%) concentrations of oxygen, i.e., GSH depletion reduced the [O/sub 2/] necessary to achieve an equivalent ER by 8-10 fold. Furthermore, while the addition of exogenous 5 mM GSH restored the ER to that observed when GSH was not depleted, the intracellular [GSH] was not increased. The results of these studies carried out at different levels of GSH depletion are presented

Microbial respiration and gene expression as a function of very low oxygen concentration

DEFF Research Database (Denmark)

Tiano, Laura

and denitrification, were only partially described. In spite of the importance of aerobic respiration as a key process in the global carbon cycle, the available data are still few, and highly biased with respect to season, latitude and depth. The main aims of this Ph.D were to: i) develop and test a highly...... to pure cultures (Manuscript III), in order to assess the response of three species of NOB (Nitrospira defluvvi, N. moscoviensis and Nitrospina gracilis) to low O2 concentrations, and the oxygen regulation on the expression of the terminal oxidases genes in N.moscoviensis. The oxygen affinities...... of these pure cultures were lower than found for natural communities of NOB (apparent Km values~ 1- 4 µM), but higher than the ones from the well-studied opportunistic NOB Nitrobacter. The expression of high-affinity terminal oxidases in these NOB could, however, not be confirmed. Overall the results of this Ph...

The oxygen effect and adaptive response of cells. Report 3. Simulation of respiratory oxygenation and oxygen permeability of cells

International Nuclear Information System (INIS)

Ehpshtejn, I.M.

1978-01-01

Variations in the oxygen concentration in extracellural [O 2 ] 0 and intracellular [Osub(2)]sub(i) media of cells small in size (d = 2 ] 0 - t-curves). It is shown that the Value of [Osub(2)]sub(i) may be expressed by four variants of its functional dependence: (a) on enzymic reaction of oxygen consumption, (b) on the order of reaction with respect to oxygen, (c) on physiological parameters of cells, and (d) on characteristic oxygen concentrations in the system. Items (c) and (d) are based on the postulated diffusion-kinetic model of oxygen consumption by an idealized cell of small size that consists of a drop of homogenous solution of the respiratory enzyme which is characterized by an equivalent Michaelis constant. The drop is enveloped in a uniform membrane that possesses a definite diffuse resistance to oxygen

Spatially monitoring oxygen level in 3D microfabricated cell culture systems using optical oxygen sensing beads.

Science.gov (United States)

Wang, Lin; Acosta, Miguel A; Leach, Jennie B; Carrier, Rebecca L

2013-04-21

Capability of measuring and monitoring local oxygen concentration at the single cell level (tens of microns scale) is often desirable but difficult to achieve in cell culture. In this study, biocompatible oxygen sensing beads were prepared and tested for their potential for real-time monitoring and mapping of local oxygen concentration in 3D micro-patterned cell culture systems. Each oxygen sensing bead is composed of a silica core loaded with both an oxygen sensitive Ru(Ph2phen3)Cl2 dye and oxygen insensitive Nile blue reference dye, and a poly-dimethylsiloxane (PDMS) shell rendering biocompatibility. Human intestinal epithelial Caco-2 cells were cultivated on a series of PDMS and type I collagen based substrates patterned with micro-well arrays for 3 or 7 days, and then brought into contact with oxygen sensing beads. Using an image analysis algorithm to convert florescence intensity of beads to partial oxygen pressure in the culture system, tens of microns-size oxygen sensing beads enabled the spatial measurement of local oxygen concentration in the microfabricated system. Results generally indicated lower oxygen level inside wells than on top of wells, and local oxygen level dependence on structural features of cell culture surfaces. Interestingly, chemical composition of cell culture substrates also appeared to affect oxygen level, with type-I collagen based cell culture systems having lower oxygen concentration compared to PDMS based cell culture systems. In general, results suggest that oxygen sensing beads can be utilized to achieve real-time and local monitoring of micro-environment oxygen level in 3D microfabricated cell culture systems.

Reduced muscle activation during exercise related to brain oxygenation and metabolism in humans

DEFF Research Database (Denmark)

Rasmussen, Peter; Nielsen, Jannie; Overgaard, M

2010-01-01

Maximal exercise may be limited by central fatigue defined as an inability of the central nervous system to fully recruit the involved muscles. This study evaluated whether a reduction in the cerebral oxygen-to-carbohydrate index (OCI) and in the cerebral mitochondrial oxygen tension relate to th...... indicating that reduced cerebral oxygenation may play a role in the development of central fatigue and may be an exercise capacity limiting factor.......Maximal exercise may be limited by central fatigue defined as an inability of the central nervous system to fully recruit the involved muscles. This study evaluated whether a reduction in the cerebral oxygen-to-carbohydrate index (OCI) and in the cerebral mitochondrial oxygen tension relate...... of perceived exertion (RPE), arm maximal voluntary force (MVC), and voluntary activation of elbow flexor muscles assessed with transcranial magnetic stimulation. Low intensity exercise did not produce any indication of central fatigue or marked cerebral metabolic deviations. Exercise in hypoxia (0.10) reduced...

Oxygen potentials, oxygen diffusion coefficients and defect equilibria of nonstoichiometric (U,Pu)O{sub 2±x}

Energy Technology Data Exchange (ETDEWEB)

Kato, Masato, E-mail: kato.masato@jaea.go.jp [Fukushima Fuels and Materials Department, Japan Atomic Energy Agency, 4002 Narita-chou, O-arai machi, Ibaraki 311-1919 (Japan); Fast Reactor Fuel Cycle Technology Development Division, Japan Atomic Energy Agency, 4-33 Muramatsu Tokai-mura, Ibaraki 319-1194 (Japan); Watanabe, Masashi [Fukushima Fuels and Materials Department, Japan Atomic Energy Agency, 4002 Narita-chou, O-arai machi, Ibaraki 311-1919 (Japan); Fast Reactor Fuel Cycle Technology Development Division, Japan Atomic Energy Agency, 4-33 Muramatsu Tokai-mura, Ibaraki 319-1194 (Japan); Matsumoto, Taku; Hirooka, Shun; Akashi, Masatoshi [Fast Reactor Fuel Cycle Technology Development Division, Japan Atomic Energy Agency, 4-33 Muramatsu Tokai-mura, Ibaraki 319-1194 (Japan)

2017-04-15

Oxygen potential of (U,Pu)O{sub 2±x} was evaluated based on defect chemistry using an updated experimental data set. The relationship between oxygen partial pressure and deviation x in (U,Pu)O{sub 2±x} was analyzed, and equilibrium constants of defect formation were determined as functions of Pu content and temperature. Brouwer's diagrams were constructed using the determined equilibrium constants, and a relational equation to determine O/M ratio was derived as functions of O/M ratio, Pu content and temperature. In addition, relationship between oxygen potential and oxygen diffusion coefficients were described. - Highlights: •Brouwer’s diagrams for (U,Pu)O2 were constructed using the updated oxygen potential experimental data set. •Equilibrium constants of defect formation were determined as functions of Pu content and temperature. •Oxygen potential, oxygen diffusion coefficients, point defect concentration were described as functions of O/M ratio, Pu content and temperature.

Measuring a 10,000-fold enhancement of singlet molecular oxygen (1O2*) concentration on illuminated ice relative to the corresponding liquid solution

Science.gov (United States)

Bower, Jonathan P.; Anastasio, Cort

2013-08-01

Much attention has focused on the highly reactive hydroxyl radical in the oxidation of trace organic compounds on snow and ice (and subsequent release of volatile organics to the atmospheric boundary layer) but other oxidants are likely also important in this processing. Here we examine the ice chemistry of singlet molecular oxygen (1O2*), which can be significant in atmospheric water drops but has not been examined in ice or snow. To examine 1O2* on ice we illuminate laboratory ices containing Rose Bengal (RB) as the source of 1O2*, furfuryl alcohol (FFA) as the probe, and Na2SO4 to control the total solute concentration. We find that the 1O2*-mediated loss of FFA (and, thus, the 1O2* concentration) is up to 11,000 times greater on ice than in the equivalent liquid sample at the same photon flux. We attribute this large increase in the 1O2* steady-state concentration to the freeze-concentration of solutes into liquid-like regions (LLRs) in/on ice: compared to the initial solution, in the LLRs of ice the sources for 1O2* are highly concentrated, while the concentration of the dominant sink for 1O2* (i.e., water) remains largely unchanged. Similar to results expected in liquid solution, rates of FFA loss in ice depend on both the initial sensitizer concentration and temperature, providing evidence that these reactions occur in LLRs. However, we find that the enhancement in 1O2* concentrations on ice does not follow predictions from freezing-point depression, likely because experiments were conducted below the eutectic temperature for sodium sulfate, where all of the salt should have precipitated. We also explore a method for separating 1O2* and rad OH contributions to FFA oxidation in laboratory ices and show its application to two natural snow samples. We find that 1O2* concentrations in these snows are approximately 100 times higher than observed in polluted, mid-latitude fog waters, showing that the enhancement of 1O2* on ice is environmentally relevant and that

Defect chemistry modelling of oxygen-stoichiometry, vacancy concentrations, and conductivity of (La1-xSrx)(y)MnO3 +/-delta

DEFF Research Database (Denmark)

Poulsen, F.W.

2000-01-01

model, based on delocalised electrons, electron holes and all B-ions being trivalent is given in Appendix A. The sequential mathematical method allows us to calculate the high temperature oxygen partial pressure dependent properties of (La1-xSrx)(y)MnO3+/-delta in a unified manner irrespective...... are calculated by the small polaron model containing only ionic species - the B-ion may be Mn-B' (Mn2+), Mn-B(x) (Mn3+), and Mn-B(Mn4+). The A/B-ratio = y greatly influences the oxygen stoichiometry, oxygen ion vacancy- and cation vacancy concentrations and the total conductivity. Calculations are given...

Measurement of excited oxygen (O2:[sup 1][Delta]g) concentration by spontaneous emission. Hakko kyodo ni yoru reiki sanso ([sup 1][Delta]g) nodo no sokutei

Energy Technology Data Exchange (ETDEWEB)

Takahashi, S.; Hasegawa, Y.; Yamashita, I. (Mechanical Engineering Laboratory, Tsukuba (Japan))

1993-11-25

The concentration of excited oxygen ([sup 1][Delta]g), which was generated by microwave discharge in a pure oxygen flow, was measured from the intensity of spontaneous emission. The conversion factor to density was determined by spectroscopic analysis of the rotational structure and calibration of the emission intensity using a black-body furnace as light source. Consequently, a good agreement was found between the observed profiles and those calculated from spectroscopic data, and it was illustrated that the absolute concentration can be obtained by coupling band analysis and the calibration method. In addition, even when the concentration was low, it was shown that the excited oxygen concentration can be measured by considering the reflection at the cell wall. The excited oxygen concentration at the microwave discharge cavity was estimated to be around 1% under the pressure ranging from 0.5 torr to 2 torr. Furthermore, the comparison of the profiles calculated at different temperature provided that the band profile can be a good indicator of gas temperature when the signal-to-noise ratio is high. 9 refs., 10 figs., 2 tabs.

Preliminary Study of Oxygen-Enhanced Longitudinal Relaxation in MRI: A Potential Novel Biomarker of Oxygenation Changes in Solid Tumors

International Nuclear Information System (INIS)

O'Connor, James P.B.; Naish, Josephine H.; Parker, Geoff J.M.; Waterton, John C.; Watson, Yvonne; Jayson, Gordon C.; Buonaccorsi, Giovanni A.; Cheung, Sue; Buckley, David L.; McGrath, Deirdre M.; West, Catharine M.L.; Davidson, Susan E.; Roberts, Caleb; Mills, Samantha J.; Mitchell, Claire L.; Hope, Lynn; Ton, N. Chan; Jackson, Alan

2009-01-01

Purpose: There is considerable interest in developing non-invasive methods of mapping tumor hypoxia. Changes in tissue oxygen concentration produce proportional changes in the magnetic resonance imaging (MRI) longitudinal relaxation rate (R 1 ). This technique has been used previously to evaluate oxygen delivery to healthy tissues and is distinct from blood oxygenation level-dependent (BOLD) imaging. Here we report application of this method to detect alteration in tumor oxygenation status. Methods and materials: Ten patients with advanced cancer of the abdomen and pelvis underwent serial measurement of tumor R 1 while breathing medical air (21% oxygen) followed by 100% oxygen (oxygen-enhanced MRI). Gadolinium-based dynamic contrast-enhanced MRI was then performed to compare the spatial distribution of perfusion with that of oxygen-induced ΔR 1 . Results: ΔR 1 showed significant increases of 0.021 to 0.058 s -1 in eight patients with either locally recurrent tumor from cervical and hepatocellular carcinomas or metastases from ovarian and colorectal carcinomas. In general, there was congruency between perfusion and oxygen concentration. However, regional mismatch was observed in some tumor cores. Here, moderate gadolinium uptake (consistent with moderate perfusion) was associated with low area under the ΔR 1 curve (consistent with minimal increase in oxygen concentration). Conclusions: These results provide evidence that oxygen-enhanced longitudinal relaxation can monitor changes in tumor oxygen concentration. The technique shows promise in identifying hypoxic regions within tumors and may enable spatial mapping of change in tumor oxygen concentration.

Modeling of Nonlinear Dynamics and Synchronized Oscillations of Microbial Populations, Carbon and Oxygen Concentrations, Induced by Root Exudation in the Rhizosphere

Science.gov (United States)

Molz, F. J.; Faybishenko, B.; Jenkins, E. W.

2012-12-01

Mass and energy fluxes within the soil-plant-atmosphere continuum are highly coupled and inherently nonlinear. The main focus of this presentation is to demonstrate the results of numerical modeling of a system of 4 coupled, nonlinear ordinary differential equations (ODEs), which are used to describe the long-term, rhizosphere processes of soil microbial dynamics, including the competition between nitrogen-fixing bacteria and those unable to fix nitrogen, along with substrate concentration (nutrient supply) and oxygen concentration. Modeling results demonstrate the synchronized patterns of temporal oscillations of competing microbial populations, which are affected by carbon and oxygen concentrations. The temporal dynamics and amplitude of the root exudation process serve as a driving force for microbial and geochemical phenomena, and lead to the development of the Gompetzian dynamics, synchronized oscillations, and phase-space attractors of microbial populations and carbon and oxygen concentrations. The nonlinear dynamic analysis of time series concentrations from the solution of the ODEs was used to identify several types of phase-space attractors, which appear to be dependent on the parameters of the exudation function and Monod kinetic parameters. This phase space analysis was conducted by means of assessing the global and local embedding dimensions, correlation time, capacity and correlation dimensions, and Lyapunov exponents of the calculated model variables defining the phase space. Such results can be used for planning experimental and theoretical studies of biogeochemical processes in the fields of plant nutrition, phyto- and bio-remediation, and other ecological areas.

Influences of dissolved oxygen concentration on biocathodic microbial communities in microbial fuel cells.

Science.gov (United States)

Rago, Laura; Cristiani, Pierangela; Villa, Federica; Zecchin, Sarah; Colombo, Alessandra; Cavalca, Lucia; Schievano, Andrea

2017-08-01

Dissolved oxygen (DO) at cathodic interface is a critical factor influencing microbial fuel cells (MFC) performance. In this work, three MFCs were operated with cathode under different DO conditions: i) air-breathing (A-MFC); ii) water-submerged (W-MFC) and iii) assisted by photosynthetic microorganisms (P-MFC). A plateau of maximum current was reached at 1.06±0.03mA, 1.48±0.06mA and 1.66±0.04mA, increasing respectively for W-MFC, P-MFC and A-MFC. Electrochemical and microbiological tools (Illumina sequencing, confocal microscopy and biofilm cryosectioning) were used to explore anodic and cathodic biofilm in each MFC type. In all cases, biocathodes improved oxygen reduction reaction (ORR) as compared to abiotic condition and A-MFC was the best performing system. Photosynthetic cultures in the cathodic chamber supplied high DO level, up to 16mg O2 L -1 , which sustained aerobic microbial community in P-MFC biocathode. Halomonas, Pseudomonas and other microaerophilic genera reached >50% of the total OTUs. The presence of sulfur reducing bacteria (Desulfuromonas) and purple non-sulfur bacteria in A-MFC biocathode suggested that the recirculation of sulfur compounds could shuttle electrons to sustain the reduction of oxygen as final electron acceptor. The low DO concentration limited the cathode in W-MFC. A model of two different possible microbial mechanisms is proposed which can drive predominantly cathodic ORR. Copyright © 2017 Elsevier B.V. All rights reserved.

Spatially monitoring oxygen level in 3D microfabricated cell culture systems using optical oxygen sensing beads

OpenAIRE

Wang, Lin; Acosta, Miguel A.; Leach, Jennie B.; Carrier, Rebecca L.

2013-01-01

Capability of measuring and monitoring local oxygen concentration at the single cell level (tens of microns scale) is often desirable but difficult to achieve in cell culture. In this study, biocompatible oxygen sensing beads were prepared and tested for their potential for real-time monitoring and mapping of local oxygen concentration in 3D micro-patterned cell culture systems. Each oxygen sensing bead is composed of a silica core loaded with both an oxygen sensitive Ru(Ph2phen3)Cl2 dye and ...

Radon concentration and its relation with some environmental conditions in the northern safaga bay

International Nuclear Information System (INIS)

Al-Arabi, A.M.; Tartor, B.A.; Bashter, I.I.; El-Saman, M.I.; Maiyza, I.A.

2005-01-01

The coastal zone along the Red Sea at Safaga town is a site for industrial development and accepting future establishment of dense recreational resorts. It includes Safaga harbour in which international trade depends. Until now most of the coastal area at Safaga is pristine and suffering from continuous increasing population densities. There is no idea about the distribution of hydro graphic parameters or radon level in the northern Safaga bay in spite of the area famous as the treatment area for Psoriases and Rheumatoid as will as attractive area for tourism. The relative high relations exist between the radioactivity component and the ph, specific conductivity, water salinity, water density and dissolved oxygen were calculated. The concentration of 226 R a, 232 T h and 40 K in sediment samples collected from bottom of the northern Safaga Bay fluctuated between 5 to 19 Bq.kg-1, 4 to 19 Bq.kg-1 and 1545 to 6122 Bq.kg-1, respectively. Whereas the concentration of radon air varies between 2 -11 Bq.cm-3

Atmospheric relative concentrations in building wakes

International Nuclear Information System (INIS)

Ramsdell, J.V. Jr.; Simonen, C.A.; Smyth, S.B.

1995-05-01

This report documents the ARCON95 computer code developed for the U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research for use in control room habitability assessments. The document includes a user's guide to the code, a description of the technical basis for the code, and a programmer's guide to the code. The ARCON95 code uses hourly meteorological data and recently developed methods for estimating dispersion in the vicinity of buildings to calculate relative concentrations at control room air intakes that would be exceeded no more five percent of the time. These concentrations are calculated for averaging periods ranging from one hour to 30 days in duration. Relative concentrations calculated by ARCON95 are significantly lower than concentrations calculated using the currently accepted procedure when winds are less than two meters per second. For higher wind speeds, ARCON95 calculates about the same concentrations as the current procedure

Optimal oxygen saturation in premature infants

Directory of Open Access Journals (Sweden)

Meayoung Chang

2011-09-01

Full Text Available There is a delicate balance between too little and too much supplemental oxygen exposure in premature infants. Since underuse and overuse of supplemental oxygen can harm premature infants, oxygen saturation levels must be monitored and kept at less than 95% to prevent reactive oxygen species-related diseases, such as retinopathy of prematurity and bronchopulmonary dysplasia. At the same time, desaturation below 80 to 85% must be avoided to prevent adverse consequences, such as cerebral palsy. It is still unclear what range of oxygen saturation is appropriate for premature infants; however, until the results of further studies are available, a reasonable target for pulse oxygen saturation (SpO2 is 90 to 93% with an intermittent review of the correlation between SpO2 and the partial pressure of arterial oxygen tension (PaO2. Because optimal oxygenation depends on individuals at the bedside making ongoing adjustments, each unit must define an optimal target range and set alarm limits according to their own equipment or conditions. All staff must be aware of these values and adjust the concentration of supplemental oxygen frequently.

Kinetics of oxygen species in an electrically driven singlet oxygen generator

International Nuclear Information System (INIS)

Azyazov, V.N.; Torbin, A.P.; Pershin, A.A.; Mikheyev, P.A.; Heaven, M.C.

2015-01-01

Highlights: • Vibrational excitation of O_3 increases the rate constant for O_3 + O_2(a) → 2O_2(X) + O. • Vibrationally excited O_3 is produced by the O + O_2(X) + M → O_3 + M reaction. • Ozone concentrations are impacted by the reactions of vibrationally excited O_3. • Relevant to ozone concentrations in oxygen discharges and the upper atmosphere. - Abstract: The kinetics of oxygen species in the gaseous medium of a discharge singlet oxygen generator has been revisited. Vibrationally excited ozone O_3(υ) formed in O + O_2 recombination is thought to be a significant agent in the deactivation of singlet oxygen O_2(a"1Δ), oxygen atom removal and ozone formation. It is shown that the process O_3(υ ⩾ 2) + O_2(a"1Δ) → 2O_2 + O is the main O_2(a"1Δ) deactivation channel in the post-discharge zone. If no measures are taken to decrease the oxygen atom concentration, the contribution of this process to the overall O_2(a"1Δ) removal is significant, even in the discharge zone. A simplified model for the kinetics of vibrationally excited ozone is proposed. Calculations based on this model yield results that are in good agreement with the experimental data.

Thermodynamic Analysis of Oxygen-Enriched Direct Smelting of Jamesonite Concentrate

Science.gov (United States)

Zhang, Zhong-Tang; Dai, Xi; Zhang, Wen-Hai

2017-12-01

Thermodynamic analysis of oxygen-enriched direct smelting of jamesonite concentrate is reported in this article. First, the occurrence state of lead, antimony and other metallic elements in the smelting process was investigated theoretically. Then, the verification test was carried out. The results indicate that lead and antimony mainly exist in the alloy in the form of metallic lead and metallic antimony. Simultaneously, lead and antimony were also oxidized into the slag in the form of lead-antimony oxide. Iron and copper could be oxidized into the slag in the form of oxides in addition to combining with antimony in the alloy, while zinc was mainly oxidized into the slag in the form of zinc oxide. The verification test indicates that the main phases in the alloy contain metallic lead, metallic antimony and a small amount of Cu2Sb, FeSb2 intermetallic compounds, and the slag is mainly composed of kirschsteinite, fayalite and zinc oxide, in agreement with the thermodynamic analysis.

Differential concentration-specific effects of caffeine on cell viability, oxidative stress, and cell cycle in pulmonary oxygen toxicity in vitro

International Nuclear Information System (INIS)

Tiwari, Kirti Kumar; Chu, Chun; Couroucli, Xanthi; Moorthy, Bhagavatula; Lingappan, Krithika

2014-01-01

Highlights: • Caffeine at 0.05 mM decreases oxidative stress in hyperoxia. • Caffeine at 1 mM decreases cell viability, increases oxidative stress in hyperoxia. • Caffeine at 1 but not 0.05 mM, abrogates hyperoxia-induced G2/M arrest. - Abstract: Caffeine is used to prevent bronchopulmonary dysplasia (BPD) in premature neonates. Hyperoxia contributes to the development of BPD, inhibits cell proliferation and decreases cell survival. The mechanisms responsible for the protective effect of caffeine in pulmonary oxygen toxicity remain largely unknown. A549 and MLE 12 pulmonary epithelial cells were exposed to hyperoxia or maintained in room air, in the presence of different concentrations (0, 0.05, 0.1 and 1 mM) of caffeine. Caffeine had a differential concentration-specific effect on cell cycle progression, oxidative stress and viability, with 1 mM concentration being deleterious and 0.05 mM being protective. Reactive oxygen species (ROS) generation during hyperoxia was modulated by caffeine in a similar concentration-specific manner. Caffeine at 1 mM, but not at the 0.05 mM concentration decreased the G2 arrest in these cells. Taken together this study shows the novel funding that caffeine has a concentration-specific effect on cell cycle regulation, ROS generation, and cell survival in hyperoxic conditions

Differential concentration-specific effects of caffeine on cell viability, oxidative stress, and cell cycle in pulmonary oxygen toxicity in vitro

Energy Technology Data Exchange (ETDEWEB)

Tiwari, Kirti Kumar; Chu, Chun; Couroucli, Xanthi; Moorthy, Bhagavatula; Lingappan, Krithika, E-mail: lingappa@bcm.edu

2014-08-08

Highlights: • Caffeine at 0.05 mM decreases oxidative stress in hyperoxia. • Caffeine at 1 mM decreases cell viability, increases oxidative stress in hyperoxia. • Caffeine at 1 but not 0.05 mM, abrogates hyperoxia-induced G2/M arrest. - Abstract: Caffeine is used to prevent bronchopulmonary dysplasia (BPD) in premature neonates. Hyperoxia contributes to the development of BPD, inhibits cell proliferation and decreases cell survival. The mechanisms responsible for the protective effect of caffeine in pulmonary oxygen toxicity remain largely unknown. A549 and MLE 12 pulmonary epithelial cells were exposed to hyperoxia or maintained in room air, in the presence of different concentrations (0, 0.05, 0.1 and 1 mM) of caffeine. Caffeine had a differential concentration-specific effect on cell cycle progression, oxidative stress and viability, with 1 mM concentration being deleterious and 0.05 mM being protective. Reactive oxygen species (ROS) generation during hyperoxia was modulated by caffeine in a similar concentration-specific manner. Caffeine at 1 mM, but not at the 0.05 mM concentration decreased the G2 arrest in these cells. Taken together this study shows the novel funding that caffeine has a concentration-specific effect on cell cycle regulation, ROS generation, and cell survival in hyperoxic conditions.

Oxygen supply in aquatic ectotherms: partial pressure and solubility together explain biodiversity and size patterns.

Science.gov (United States)

Verberk, Wilco C E P; Bilton, David T; Calosi, Piero; Spicer, John I

2011-08-01

Aquatic ectotherms face the continuous challenge of capturing sufficient oxygen from their environment as the diffusion rate of oxygen in water is 3 x 10(5) times lower than in air. Despite the recognized importance of oxygen in shaping aquatic communities, consensus on what drives environmental oxygen availability is lacking. Physiologists emphasize oxygen partial pressure, while ecologists emphasize oxygen solubility, traditionally expressing oxygen in terms of concentrations. To resolve the question of whether partial pressure or solubility limits oxygen supply in nature, we return to first principles and derive an index of oxygen supply from Fick's classic first law of diffusion. This oxygen supply index (OSI) incorporates both partial pressure and solubility. Our OSI successfully explains published patterns in body size and species across environmental clines linked to differences in oxygen partial pressure (altitude, organic pollution) or oxygen solubility (temperature and salinity). Moreover, the OSI was more accurately and consistently related to these ecological patterns than other measures of oxygen (oxygen saturation, dissolved oxygen concentration, biochemical oxygen demand concentrations) and similarly outperformed temperature and altitude, which covaried with these environmental clines. Intriguingly, by incorporating gas diffusion rates, it becomes clear that actually more oxygen is available to an organism in warmer habitats where lower oxygen concentrations would suggest the reverse. Under our model, the observed reductions in aerobic performance in warmer habitats do not arise from lower oxygen concentrations, but instead through organismal oxygen demand exceeding supply. This reappraisal of how organismal thermal physiology and oxygen demands together shape aerobic performance in aquatic ectotherms and the new insight of how these components change with temperature have broad implications for predicting the responses of aquatic communities to

Dependence of nitrite oxidation on nitrite and oxygen in low-oxygen seawater

Science.gov (United States)

Sun, Xin; Ji, Qixing; Jayakumar, Amal; Ward, Bess B.

2017-08-01

Nitrite oxidation is an essential step in transformations of fixed nitrogen. The physiology of nitrite oxidizing bacteria (NOB) implies that the rates of nitrite oxidation should be controlled by concentration of their substrate, nitrite, and the terminal electron acceptor, oxygen. The sensitivities of nitrite oxidation to oxygen and nitrite concentrations were investigated using 15N tracer incubations in the Eastern Tropical North Pacific. Nitrite stimulated nitrite oxidation under low in situ nitrite conditions, following Michaelis-Menten kinetics, indicating that nitrite was the limiting substrate. The nitrite half-saturation constant (Ks = 0.254 ± 0.161 μM) was 1-3 orders of magnitude lower than in cultivated NOB, indicating higher affinity of marine NOB for nitrite. The highest rates of nitrite oxidation were measured in the oxygen depleted zone (ODZ), and were partially inhibited by additions of oxygen. This oxygen sensitivity suggests that ODZ specialist NOB, adapted to low-oxygen conditions, are responsible for apparently anaerobic nitrite oxidation.

MANAGEMENT PROCESS OF CULTIVATION OF MICROORGANISMS ON DYNAMICS OF TEMPERATURE OF A BIOMASS AND CONCENTRATION OF OXYGEN IN EXHAUST GASES

Directory of Open Access Journals (Sweden)

B. A. Golodenko

2012-01-01

Full Text Available On an example of industrial production of baking yeast the way of automatic control of process of cultivation of microorganisms is stated. The way provides management of aeration of a biomass on the set speed of change of its concentration and temperatures in view of speed of change of concentration of oxygen in the fulfilled gases.

Crossed Optical Fiber Sensor Arrays for High-Spatial-Resolution Sensing: Application to Dissolved Oxygen Concentration Measurements

Directory of Open Access Journals (Sweden)

M. Veronica Rigo

2012-01-01

Full Text Available Optical fiber sensors using luminescent probes located along an optical fiber in the cladding of this fiber are of great interest for monitoring physical and chemical properties in their environment. The interrogation of a luminophore with a short laser pulse propagating through the fiber core allows for the measurement of the location of these luminophores. To increase the spatial resolution of such a measurements and to measure multiple analytes and properties in a confined space, a crossed optical fiber sensing platform can be employed. Here we describe the application of this platform to measuring the concentration of dissolved oxygen. The sensor is based on luminescence quenching of a ruthenium complex immobilized in a highly crosslinked film and covalently attached to the optical fibers. Both luminescence-intensity and luminescence-lifetime changes of the sensor molecules in response to changes in the concentration of oxygen dissolved in water are reported. For luminescence-intensity measurements, a second adjacent sensor region is employed as reference to account for laser pulse energy fluctuations. Enhanced quenching response in water is demonstrated by the use of organically modified poly(ethylene glycol precursors, which increase the hydrophobicity of the film surface.

Osmotic phenomena in application for hyperbaric oxygen treatment.

Science.gov (United States)

Babchin, A; Levich, E; Melamed M D, Y; Sivashinsky, G

2011-03-01

Hyperbaric oxygen (HBO) treatment defines the medical procedure when the patient inhales pure oxygen at elevated pressure conditions. Many diseases and all injuries are associated with a lack of oxygen in tissues, known as hypoxia. HBO provides an effective method for fast oxygen delivery in medical practice. The exact mechanism of the oxygen transport under HBO conditions is not fully identified. The objective of this article is to extend the colloid and surface science basis for the oxygen transport in HBO conditions beyond the molecular diffusion transport mechanism. At a pressure in the hyperbaric chamber of two atmospheres, the partial pressure of oxygen in the blood plasma increases 10 times. The sharp increase of oxygen concentration in the blood plasma creates a considerable concentration gradient between the oxygen dissolved in the plasma and in the tissue. The concentration gradient of oxygen as a non-electrolyte solute causes an osmotic flow of blood plasma with dissolved oxygen. In other words, the molecular diffusion transport of oxygen is supplemented by the convective diffusion raised due to the osmotic flow, accelerating the oxygen delivery from blood to tissue. A non steady state equation for non-electrolyte osmosis is solved asymptotically. The solution clearly demonstrates two modes of osmotic flow: normal osmosis, directed from lower to higher solute concentrations, and anomalous osmosis, directed from higher to lower solute concentrations. The fast delivery of oxygen from blood to tissue is explained on the basis of the strong molecular interaction between the oxygen and the tissue, causing an influx of oxygen into the tissue by convective diffusion in the anomalous osmosis process. The transport of the second gas, nitrogen, dissolved in the blood plasma, is also taken into the consideration. As the patient does not inhale nitrogen during HBO treatment, but exhales it along with oxygen and carbon dioxide, the concentration of nitrogen in blood

Radiosensitizers and the oxygen effects in mammalian cells

International Nuclear Information System (INIS)

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.)

Atmospheric relative concentrations in building wakes

International Nuclear Information System (INIS)

Ramsdell, J.V. Jr.; Simonen, C.A.

1997-05-01

This report documents the ARCON96 computer code developed for the U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation for potential use in control room habitability assessments. It includes a user's guide to the code, a description of the technical basis for the code, and a programmer's guide to the code. The ARCON96 code uses hourly meteorological data and recently developed methods for estimating dispersion in the vicinity of buildings to calculate relative concentrations at control room air intakes that would be exceeded no more than five percent of the time. The concentrations are calculated for averaging periods ranging from one hour to 30 days in duration. ARCON96 is a revised version of ARCON95, which was developed for the NRC Office of Nuclear Regulatory Research. Changes in the code permit users to simulate releases from area sources as well as point sources. The method of averaging concentrations for periods longer than 2 hours has also been changed. The change in averaging procedures increases relative concentrations for these averaging periods. In general, the increase in concentrations is less than a factor of two. The increase is greatest for relatively short averaging periods, for example 0 to 8 hours and diminishes as the duration of the averaging period increases

Oxygen dependency of germinating Brassica seeds

Science.gov (United States)

Park, Myoung Ryoul; Hasenstein, Karl H.

2016-02-01

Establishing plants in space, Moon or Mars requires adaptation to altered conditions, including reduced pressure and composition of atmospheres. To determine the oxygen requirements for seed germination, we imbibed Brassica rapa seeds under varying oxygen concentrations and profiled the transcription patterns of genes related to early metabolism such as starch degradation, glycolysis, and fermentation. We also analyzed the activity of lactate dehydrogenase (LDH) and alcohol dehydrogenase (ADH), and measured starch degradation. Partial oxygen pressure (pO2) greater than 10% resulted in normal germination (i.e., protrusion of radicle about 18 hours after imbibition) but lower pO2 delayed and reduced germination. Imbibition in an oxygen-free atmosphere for three days resulted in no germination but subsequent transfer to air initiated germination in 75% of the seeds and the root growth rate was transiently greater than in roots germinated under ambient pO2. In hypoxic seeds soluble sugars degraded faster but the content of starch after 24 h was higher than at ambient oxygen. Transcription of genes related to starch degradation, α-amylase (AMY) and Sucrose Synthase (SUS), was higher under ambient O2 than under hypoxia. Glycolysis and fermentation pathway-related genes, glucose phosphate isomerase (GPI), 6-phosphofructokinase (PFK), fructose 1,6-bisphosphate aldolase (ALD), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate decarboxylase (PDC), LDH, and ADH, were induced by low pO2. The activity of LDH and ADH was the highest in anoxic seeds. Germination under low O2 conditions initiated ethanolic fermentation. Therefore, sufficient oxygen availability is important for germination before photosynthesis provides necessary oxygen and the determination of an oxygen carrying capacity is important for uniform growth in space conditions.

On the Go with Oxygen

Science.gov (United States)

... for both the patient and the oxygen supply company. There are two types of concentrators: Stationary concentrators plug into an electrical ... stationary unit. If your oxygen needs change, the type of system can ... supply company should explain and demonstrate whatever system you choose. ...

Effect of SO2 concentration on polyphenol development during red wine micro-oxygenation.

Science.gov (United States)

Tao, Jianxiong; Dykes, Stuart I; Kilmartin, Paul A

2007-07-25

A Merlot wine in 15 L research tanks was subjected to micro-oxygenation at 10 mL O2 per liter of wine per month over a 16 week period with additions of 0, 50, 100, and 200 mg/L SO2. A large decrease in monomeric anthocyanins and flavan-3-ols was seen in wines with a lower concentration of SO2, coupled with an increase in nonbleachable pigments; an increase in tannin, measured using precipitation with methyl cellulose; and a greater size and red coloration of a proanthocyanidin extract obtained using Sephadex LH-20. These changes were largely suppressed in wines initially treated with 200 mg/L SO2 and occurred more slowly in wines stored in bottles in the absence of O2. The concentration of SO2 is shown to regulate the polyphenol chemistry involved in the formation of polymeric pigments and changes in tannin structure affecting wine astringency.

Kinetics of oxygen species in an electrically driven singlet oxygen generator

Energy Technology Data Exchange (ETDEWEB)

Azyazov, V.N., E-mail: azyazov@fian.smr.ru [Samara State Aerospace University, 443086 (Russian Federation); Lebedev Physical Institute of RAS, Samara 443011 (Russian Federation); Torbin, A.P.; Pershin, A.A. [Samara State Aerospace University, 443086 (Russian Federation); Lebedev Physical Institute of RAS, Samara 443011 (Russian Federation); Mikheyev, P.A., E-mail: mikheyev@fian.smr.ru [Samara State Aerospace University, 443086 (Russian Federation); Lebedev Physical Institute of RAS, Samara 443011 (Russian Federation); Heaven, M.C., E-mail: mheaven@emory.edu [Emory University, Atlanta, GA 30322 (United States)

2015-12-16

Highlights: • Vibrational excitation of O{sub 3} increases the rate constant for O{sub 3} + O{sub 2}(a) → 2O{sub 2}(X) + O. • Vibrationally excited O{sub 3} is produced by the O + O{sub 2}(X) + M → O{sub 3} + M reaction. • Ozone concentrations are impacted by the reactions of vibrationally excited O{sub 3}. • Relevant to ozone concentrations in oxygen discharges and the upper atmosphere. - Abstract: The kinetics of oxygen species in the gaseous medium of a discharge singlet oxygen generator has been revisited. Vibrationally excited ozone O{sub 3}(υ) formed in O + O{sub 2} recombination is thought to be a significant agent in the deactivation of singlet oxygen O{sub 2}(a{sup 1}Δ), oxygen atom removal and ozone formation. It is shown that the process O{sub 3}(υ ⩾ 2) + O{sub 2}(a{sup 1}Δ) → 2O{sub 2} + O is the main O{sub 2}(a{sup 1}Δ) deactivation channel in the post-discharge zone. If no measures are taken to decrease the oxygen atom concentration, the contribution of this process to the overall O{sub 2}(a{sup 1}Δ) removal is significant, even in the discharge zone. A simplified model for the kinetics of vibrationally excited ozone is proposed. Calculations based on this model yield results that are in good agreement with the experimental data.

Effect of phytoremediation on concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site, Charleston, South Carolina, USA, 1998–2014

Science.gov (United States)

Landmeyer, James E.; Effinger, Thomas N.

2016-01-01

Concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site near Charleston, South Carolina, USA, have been monitored since the installation of a phytoremediation system of hybrid poplar trees in 1998. Between 2000 and 2014, the concentrations of benzene, toluene, and naphthalene (BT&N) in groundwater in the planted area have decreased. For example, in the monitoring well containing the highest concentrations of BT&N, benzene concentrations decreased from 10,200 µg/L to less than 4000 µg/L, toluene concentrations decreased from 2420 µg/L to less than 20 µg/L, and naphthalene concentrations decreased from 6840 µg/L to less than 3000 µg/L. Concentrations of BT&N in groundwater in all wells were observed to be lower during the summer months relative to the winter months of a particular year during the first few years after installing the phytoremediation system, most likely due to increased transpiration and contaminant uptake by the hybrid poplar trees during the warm summer months; this pathway of uptake by trees was confirmed by the detection of benzene, toluene, and naphthalene in trees during sampling events in 2002, and later in the study in 2012. These data suggest that the phytoremediation system affects the groundwater contaminants on a seasonal basis and, over multiple years, has resulted in a cumulative decrease in dissolved-phase contaminant concentrations in groundwater. The removal of dissolved organic contaminants from the aquifer has resulted in a lower demand on dissolved oxygen supplied by recharge and, as a result, the redox status of the groundwater has changed from anoxic to oxic conditions. This study provides much needed information for water managers and other scientists on the viability of the long-term effectiveness of phytoremediation in decreasing groundwater contaminants and increasing dissolved oxygen at sites contaminated by benzene, toluene, and naphthalene.

Efficacy of a portable oxygen concentrator with pulsed delivery for treatment of hypoxemia during equine field anesthesia.

Science.gov (United States)

Coutu, Paige; Caulkett, Nigel; Pang, Daniel; Boysen, Søren

2015-09-01

Hypoxemia is common during equine field anesthesia. Our hypothesis was that oxygen therapy from a portable oxygen concentrator would increase PaO2 during field anesthesia compared with the breathing of ambient air. Prospective clinical study. Fifteen yearling (250 - 400 kg) horses during field castration. Horses were maintained in dorsal recumbency during anesthesia with an intravenous infusion of 2000 mg ketamine and 500 mg xylazine in 1 L of 5% guaifenesin. Arterial samples for blood gas analysis were collected immediately post-induction (PI), and at 15 and 30 minutes PI. The control group (n = 6) breathed ambient air. The treatment group (n = 9) were administered pulsed-flow oxygen (192 mL per bolus) by nasal insufflation during inspiration for 15 minutes PI, then breathed ambient air. The study was performed at 1300 m above sea level. One-way and two-way repeated-measures anova with post-hoc Bonferroni tests were used for within and between-group comparisons, respectively. Significance was set at p ≤ 0.05. Mean ± SD PaO2 in controls at 0, 15 and 30 minutes PI were 46 ± 7 mmHg (6.1 ± 0.9 kPa), 42 ± 9 mmHg (5.6 ± 1.1 kPa), and 48 ± 7 mmHg (6.4 ± 0.1 kPa), respectively (p = 0.4). In treatment animals, oxygen administration significantly increased PaO2 at 15 minutes PI to 60 ± 13 mmHg (8.0 ± 1.7 kPa), compared with baseline values of 46 ± 8 mmHg (6.1 ± 1 kPa) (p = 0.007), and 30 minute PI values of 48 ± 7 mmHg (6.5 ± 0.9 kPa) (p = 0.003). These data show that a pulsed-flow delivery of oxygen can increase PaO2 in dorsally recumbent horses during field anesthesia with ketamine-xylazine-guaifenesin. The portable oxygen concentrator may help combat hypoxemia during field anesthesia in horses. © 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

Proterozoic atmospheric oxygen

DEFF Research Database (Denmark)

Canfield, Donald Eugene

2014-01-01

This article is concerned with the evolution of atmospheric oxygen concentrations through the Proterozoic Eon. In particular, this article will seek to place the history of atmospheric oxygenation through the Proterozoic Eon in the context of the evolving physical environment including the history...... of continental growth and volcanic outgassing, as well as biogeochemical processing of elements within the oceans. The author will seek to explore constraints on the history of oxygenation and understand which processes have regulated oxygen through this eon....

Investigation of concentration overpotential distribution in a polymer electrolyte fuel cell. Paper no. IGEC-1-081

International Nuclear Information System (INIS)

Tajiri, K.; Yang, X.-G.; Wang, C.-Y.; Shinohara, K.

2005-01-01

Simultaneous measurement of current and high frequency resistance (HFR) distributions has been performed using a segmented polymer electrolyte fuel cell operated with H 2 /air. Each flow plate consisted of twelve segments along a serpentine flow field. Two types of gas diffusion layer (GDL), a treated hydrophobic carbon cloth coated with a microporous layer (MPL) on one side, and an untreated hydrophilic carbon cloth without MPL, were studied and contrasted. The total voltage loss is divided into three overpotentials: the activation, ohmic and concentration; and the concentration overpotential and its distribution are analyzed in detail. While the fuel cell using the GDL with MPL features a nearly uniform concentration overpotential profile, the one without-MPL shows an increase in concentration overpotential along the cathode flow. When the local concentration overpotential is plotted against the local oxygen concentration, the carbon cloth GDL without MPL showed a steeply increasing concentration overpotential with decreasing oxygen concentration, indicating a high sensitivity to the oxygen content. The same trend was observed for the GDL without MPL under lower relative humidity gases. It is thus found that the increase in concentration overpotential with decreasing oxygen concentration is related to the absence of MPL. (author)

Solar Energy Systems for Lunar Oxygen Generation

Science.gov (United States)

Colozza, Anthony J.; Heller, Richard S.; Wong, Wayne A.; Hepp, Aloysius F.

2010-01-01

An evaluation of several solar concentrator-based systems for producing oxygen from lunar regolith was performed. The systems utilize a solar concentrator mirror to provide thermal energy for the oxygen production process. Thermal energy to power a Stirling heat engine and photovoltaics are compared for the production of electricity. The electricity produced is utilized to operate the equipment needed in the oxygen production process. The initial oxygen production method utilized in the analysis is hydrogen reduction of ilmenite. Utilizing this method of oxygen production a baseline system design was produced. This baseline system had an oxygen production rate of 0.6 kg/hr with a concentrator mirror size of 5 m. Variations were performed on the baseline design to show how changes in the system size and process (rate) affected the oxygen production rate. An evaluation of the power requirements for a carbothermal lunar regolith reduction reactor has also been conducted. The reactor had a total power requirement between 8,320 to 9,961 W when producing 1000 kg/year of oxygen. The solar concentrator used to provide the thermal power (over 82 percent of the total energy requirement) would have a diameter of less than 4 m.

Analysis of Relative Concentration of Ethanol and Other Odorous Compounds (OCs) Emitted from the Working Surface at a Landfill in China

Science.gov (United States)

Li, Dong; Lu, Wenjing; Liu, Yanjun; Guo, Hanwen; Xu, Sai; Ming, Zhongyuan; Wang, Hongtao

2015-01-01

Estimating odor emissions from landfill sites is a complicated task because of the various chemical and biological species that exist in landfill gases. In this study, the relative concentration of ethanol and other odorous compounds emitted from the working surface at a landfill in China was analyzed. Gas sampling was conducted at the landfill on a number of selected days from March 2012 to March 2014, which represented different periods throughout the two years. A total of 41, 59, 66, 54, 63, 54, 41, and 42 species of odorous compounds were identified and quantified in eight sampling activities, respectively; a number of 86 species of odorous compounds were identified and quantified all together in the study. The measured odorous compounds were classified into six different categories (Oxygenated compounds, Halogenated compounds, Terpenes, Sulfur compounds, Aromatics, and Hydrocarbons). The total average concentrations of the oxygenated compounds, sulfur compounds, aromatics, halogenated compounds, hydrocarbons, and terpenes were 2.450 mg/m3, 0.246 mg/m3, 0.203 mg/m3, 0.319 mg/m3, 0.530 mg/m3, and 0.217 mg/m3, respectively. The relative concentrations of 59 odorous compounds with respect to the concentration of ethyl alcohol (1000 ppm) were determined. The dominant contaminants that cause odor pollution around the landfill are ethyl sulfide, methyl mercaptan, acetaldehyde, and hydrogen sulfide; dimethyl disulfide and dimethyl sulfide also contribute to the pollution to a certain degree. PMID:25769100

Growth of the obligate anaerobe Desulfovibrio vulgaris Hildenborough under continuous low oxygen concentration sparging: impact of the membrane-bound oxygen reductases.

Science.gov (United States)

Ramel, Fanny; Brasseur, Gael; Pieulle, Laetitia; Valette, Odile; Hirschler-Réa, Agnès; Fardeau, Marie Laure; Dolla, Alain

2015-01-01

Although obligate anaerobe, the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough (DvH) exhibits high aerotolerance that involves several enzymatic systems, including two membrane-bound oxygen reductases, a bd-quinol oxidase and a cc(b/o)o3 cytochrome oxidase. Effect of constant low oxygen concentration on growth and morphology of the wild-type, single (Δbd, Δcox) and double deletion (Δcoxbd) mutant strains of the genes encoding these oxygen reductases was studied. When both wild-type and deletion mutant strains were cultured in lactate/sulfate medium under constant 0.02% O2 sparging, they were able to grow but the final biomasses and the growth yield were lower than that obtained under anaerobic conditions. At the end of the growth, lactate was not completely consumed and when conditions were then switched to anaerobic, growth resumed. Time-lapse microscopy revealed that a large majority of the cells were then able to divide (over 97%) but the time to recover a complete division event was longer for single deletion mutant Δbd than for the three other strains. Determination of the molar growth yields on lactate suggested that a part of the energy gained from lactate oxidation was derived toward cells protection/repairing against oxidative conditions rather than biosynthesis, and that this part was higher in the single deletion mutant Δbd and, to a lesser extent, Δcox strains. Our data show that when DvH encounters oxidative conditions, it is able to stop growing and to rapidly resume growing when conditions are switched to anaerobic, suggesting that it enters active dormancy sate under oxidative conditions. We propose that the pyruvate-ferredoxin oxidoreductase (PFOR) plays a central role in this phenomenon by reversibly switching from an oxidative-sensitive fully active state to an oxidative-insensitive inactive state. The oxygen reductases, and especially the bd-quinol oxidase, would have a crucial function by maintaining reducing conditions

Growth of the obligate anaerobe Desulfovibrio vulgaris Hildenborough under continuous low oxygen concentration sparging: impact of the membrane-bound oxygen reductases.

Directory of Open Access Journals (Sweden)

Fanny Ramel

Full Text Available Although obligate anaerobe, the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough (DvH exhibits high aerotolerance that involves several enzymatic systems, including two membrane-bound oxygen reductases, a bd-quinol oxidase and a cc(b/oo3 cytochrome oxidase. Effect of constant low oxygen concentration on growth and morphology of the wild-type, single (Δbd, Δcox and double deletion (Δcoxbd mutant strains of the genes encoding these oxygen reductases was studied. When both wild-type and deletion mutant strains were cultured in lactate/sulfate medium under constant 0.02% O2 sparging, they were able to grow but the final biomasses and the growth yield were lower than that obtained under anaerobic conditions. At the end of the growth, lactate was not completely consumed and when conditions were then switched to anaerobic, growth resumed. Time-lapse microscopy revealed that a large majority of the cells were then able to divide (over 97% but the time to recover a complete division event was longer for single deletion mutant Δbd than for the three other strains. Determination of the molar growth yields on lactate suggested that a part of the energy gained from lactate oxidation was derived toward cells protection/repairing against oxidative conditions rather than biosynthesis, and that this part was higher in the single deletion mutant Δbd and, to a lesser extent, Δcox strains. Our data show that when DvH encounters oxidative conditions, it is able to stop growing and to rapidly resume growing when conditions are switched to anaerobic, suggesting that it enters active dormancy sate under oxidative conditions. We propose that the pyruvate-ferredoxin oxidoreductase (PFOR plays a central role in this phenomenon by reversibly switching from an oxidative-sensitive fully active state to an oxidative-insensitive inactive state. The oxygen reductases, and especially the bd-quinol oxidase, would have a crucial function by maintaining

Effects of bottom water oxygen concentrations on mercury distribution and speciation in sediments below the oxygen minimum zone of the Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Chakraborty, P.; Mason, R.P.; Jayachandran, S.; Vudamala, K.; Armoury, K.; Sarkar, Arindam; Chakraborty, S.; Bardhan, P.; Naik, R.

benthic flux of MeHg to the overlying water (Hollweg et al., 2010; Balcom et al., 2008). On the contrary, however, a study in the Gulf of Mexico did not find that MeHg in bottom waters correlated with the extent of hypoxia (Liu et al., 2015... in the sediments of the so-called “dead zone” in the Gulf of Mexico. Others (Mason et al., 2006; Emili et al., 2011) have shown that total Hg and MeHg fluxes from sediments are enhanced by low oxygen concentrations in the overlying waters. The aim of this study...

3-D Numerical Investigation on Oxygen Transfer in a Horizontal Venturi Flow with Two Holes

Directory of Open Access Journals (Sweden)

Zegao Yin

2018-02-01

Full Text Available In order to investigate the dissolved oxygen increase caused by air suction in a horizontal Venturi flow with two holes, a 3-D computational fluid dynamics model was used to explore the water and bubble mixture flow, coupled with a dissolved oxygen transfer model. A series of experiments were conducted to validate the mathematical model. A relative saturation coefficient correlation was examined factoring in dissolved oxygen concentration at the inlet, water velocity at the inlet, the hole’s diameter, contraction ratio at throat section, and the downstream length of Venturi pipe. It was found that the relative saturation coefficient increases with increasing dissolved oxygen concentration at the inlet and downstream length of Venturi pipe respectively. However, it increases with decreasing water velocity at the inlet and contraction ratio at the throat section to some extent. The hole’s diameter plays a complex role in the relative saturation coefficient. The dimensional analysis method and the least square method were used to deduce a simple formula for the relative saturation coefficient, and this was consistent with related data.

Micro-oxygenation of red wine: techniques, applications, and outcomes.

Science.gov (United States)

Schmidtke, Leigh M; Clark, Andrew C; Scollary, Geoff R

2011-02-01

Wine micro-oxygenation (MOX) is the controlled addition of oxygen to wine in a manner designed to ensure that complete mass transfer of molecular oxygen from gaseous to dissolved state occurs. MOX was initially developed to improve the body, structure, and fruitfulness in red wines with high concentrations of tannins and anthocyanins, by replicating the ingress of oxygen thought to arise from barrel maturation, but without the need for putting all wine to barrel. This review describes the operational parameters essential for the effective performance of the micro-oxidation process as well as the chemical and microbiological outcomes. The methodologies for introducing oxygen into the wine, the rates of oxygen addition, and their relationship to oxygen solubility in the wine matrix are examined. The review focuses on the techniques used for monitoring the MOX process, including sensory assessment, physicochemical properties, and the critical balance of the rate of oxygen addition in relation to maintaining the sulfur dioxide concentration. The chemistry of oxygen reactivity with wine components, the changes in wine composition that occur as a consequence of MOX, and the potential for wine spoilage if proper monitoring is not adopted are examined. Gaps in existing knowledge are addressed focusing on the limitations associated with the transfer of concepts from research trials in small volume tanks to commercial practice, and the dearth of kinetic data for the various chemical and physical processes that are claimed to occur during MOX.

Feedforward-feedback control of dissolved oxygen concentration in a predenitrification system.

Science.gov (United States)

Yong, Ma; Yongzhen, Peng; Shuying, Wang

2005-07-01

As the largest single energy-consuming component in most biological wastewater treatment systems, aeration control is of great interest from the point of view of saving energy and improving wastewater treatment plant efficiency. In this paper, three different strategies, including conventional constant dissolved oxygen (DO) set-point control, cascade DO set-point control, and feedforward-feedback DO set-point control were evaluated using the denitrification layout of the IWA simulation benchmark. Simulation studies showed that the feedforward-feedback DO set-point control strategy was better than the other control strategies at meeting the effluent standards and reducing operational costs. The control strategy works primarily by feedforward control based on an ammonium sensor located at the head of the aerobic process. It has an important advantage over effluent measurements in that there is no (or only a very short) time delay for information; feedforward control was combined with slow feedback control to compensate for model approximations. The feedforward-feedback DO control was implemented in a lab-scale wastewater treatment plant for a period of 60 days. Compared to operation with constant DO concentration, the required airflow could be reduced by up to 8-15% by employing the feedforward-feedback DO-control strategy, and the effluent ammonia concentration could be reduced by up to 15-25%. This control strategy can be expected to be accepted by the operating personnel in wastewater treatment plants.

The effects of oxygen on process rates and gene expression of anammox and denitrification in the Eastern South Pacific oxygen minimum zone

DEFF Research Database (Denmark)

Dalsgaard, Tage; Stewart, Frank; De Brabandere, Loreto

Oxygen concentrations were consistently below our detection limit of 90 nM for a distance of > 2000 km in the oxygen minimum zone (OMZ) along the coasts of Chile and Peru. In most cases, anammox and denitrification were only detected when in situ oxygen concentrations were below detection...... differently to oxygen. When normalized to a housekeeping gene (rpoB), the expression of 4 out of 9 N-cycle-genes changed with increasing oxygen concentration: The expression of ammonium monooxygenase (amoC) was stimulated, whereas expression of nitrite reductase (nirS), nitric oxide reductase (nor...

Measurement and interpretation of low levels of dissolved oxygen in ground water

Science.gov (United States)

White, A.F.; Peterson, M.L.; Solbau, R.D.

1990-01-01

A Rhodazine-D colorimetric technique was adapted to measure low-level dissolved oxygen concentrations in ground water. Prepared samples containing between 0 and 8.0 ??moles L-1 dissolved oxygen in equilibrium with known gas mixtures produced linear spectrophotometric absorbance with a lower detection limit of 0.2 ??moles L-1. Excellent reproducibility was found for solutions ranging in composition from deionized water to sea water with chemical interferences detected only for easily reduced metal species such as ferric ion, cupric ion, and hexavalent chromium. Such effects were correctable based on parallel reaction stoichiometries relative to oxygen. The technique, coupled with a downhole wire line tool, permitted low-level monitoring of dissolved oxygen in wells at the selenium-contaminated Kesterson Reservoir in California. Results indicated a close association between low but measurable dissolved oxygen concentrations and mobility of oxidized forms of selenium. -from Authors

Direct measurement of oxygen in brown coals and carbochemical products by means of fast neutron analysis

International Nuclear Information System (INIS)

Raeppel, P.; Foerster, H.

1990-01-01

Analyses of elemental oxygen by means of fast neutron activation permit high-accuracy measurements of oxygen concentrations in East German brown coal; this applies to run-of-mine brown coal as well as to demineralized brown coal. The relative error was 4% in the first case and 2% in the latter case. Pre-washing with 1n ammonium acetate solution permits direct analyses of the oxygen bonded to the coal minerals. The method is applicable to other carbonaceous materials, e.g. coal ashes, solid hydrogenation residues, cokes, coal extracts, asphaltenes, oils, etc., at oxygen concentrations of 1-50%. (orig.) [de

Nature of oxygen donors and radiation defects in oxygen-doped germanium

International Nuclear Information System (INIS)

Fukuoka, Noboru; Atobe, Kozo; Honda, Makoto; Matsuda, Koji.

1991-01-01

The nature of oxygen donors and radiation defects in oxygen-doped germanium were studied through measurements of the infrared absorption spectrum, deep level transient spectroscopy spectrum and carrier concentration. It is revealed that a new donor is not formed in oxygen-doped germanium. An A-center (interstitial oxygen-vacancy pair) forms a complex with a thermal donor in its annealing stage at 60degC-140degC. The introduction rate of defects by 1.5 MeV electron irradiation was enhanced in thermal-donor-doped samples. (author)

Optical noninvasive calculation of hemoglobin components concentrations and fractional oxygen saturation using a ring-scattering pulse oximeter

Science.gov (United States)

Abdallah, Omar; Stork, Wilhelm; Muller-Glaser, Klaus

2004-06-01

The deficiencies of the currently used pulse oximeter are discussed in diverse literature. A hazardous pitfalls of this method is that the pulse oximeter will not detect carboxyhemoglobin (COHb) and methemoglobin (metHb) concentrations. This leads to incorrect measurement of oxygen saturation by carbon monoxide poisoning and methemoglobinemia. Also the total hemoglobin concentration will not be considered and can only be measured in-vitro up to now. A second pitfall of the standard pulse oximetry is that it will not be able to show a result by low perfusion of tissues. This case is available inter alia when the patient is under shock or has a low blood pressure. The new non-invasive system we designed measures the actual (fractional) oxygen saturation and hemoglobin concentration. It will enable us also to measure COHb and metHb. The measurement can be applied at better perfused body central parts. Four or more light emitting diodes (LEDs) or laser diodes (LDs) and five photodiodes (PDs) are used. The reflected light signal detected by photodiodes is processed using a modified Lambert-Beer law (I=I0×e-α.d ). According to this law, when a non scattering probe is irradiated with light having the incident intensity I0, the intensity of transmitted light I decays exponentially with the absorption coefficient a of that probe and its thickness d. Modifications of this law have been performed following the theoretical developed models in literature, Monte Carlo simulation and experimental measurement.

Oxygen Transfer Model for a Flow-Through Hollow-Fiber Membrane Biofilm Reactor

DEFF Research Database (Denmark)

Gilmore, K. R.; Little, J. C.; Smets, Barth F.

2009-01-01

overpredicted the oxygen transfer by a factor of 1.3 relative to the result calculated from the outlet gas oxygen concentration, which was considered the most accurate of the measured benchmarks. A mass transfer coefficient derived from the clean water testing with oxygen sensors at the membrane......-liquid interface was the most accurate of the predictive models (overpredicted by a factor of 1.1) while a coefficient determined by measuring bulk liquid dissolved oxygen underpredicted the oxygen transfer by a factor of 3. The mechanistic model was found to be an adequate tool for design because it used...

Study of the defects related to oxygen in Czochralski silicon destined to photovoltaic solar cells - Influence of isovalent impurities

International Nuclear Information System (INIS)

Tanay, Florent

2013-01-01

This study aims at understanding the effects of two main defects related to oxygen, the boron-oxygen complexes (responsible for light-induced degradation of the carrier lifetime) and the thermal donors (among other things, responsible for variations of the conductivity), on the electric and photovoltaic properties of silicon. More precisely, the interactions of isovalent impurities, known for modifying the oxygen spatial distribution, with these defects were studied. Two experimental protocols were first developed to evaluate the light-induced degradation of the carrier lifetime in iron-rich silicon. Then, the introduction in silicon of germanium and tin in high quantity were shown not to significantly influence the conversion efficiency of the cells. However, contrary to recent studies from the literature, no reduction due to germanium co-doping or to tin co-doping of the light-induced degradation of the photovoltaic performances was observed. However carbon was shown to lead to a slowdown of the degradation due to boron-oxygen complexes. Moreover contrary to tin which has no influence on the thermal donor generation, germanium slows down their formation. An empirical expression has been proposed to take into account this effect for a large range of germanium concentrations. Eventually in highly doped and compensated silicon, the thermal donor generation is identical as in conventional silicon, which experimentally confirms that the thermal donor formation is limited by the electron density. (author) [fr

Oxygen Transport: A Simple Model for Study and Examination.

Science.gov (United States)

Gaar, Kermit A., Jr.

1985-01-01

Describes an oxygen transport model computer program (written in Applesoft BASIC) which uses such variables as amount of time lapse from beginning of the simulation, arterial blood oxygen concentration, alveolar oxygen pressure, and venous blood oxygen concentration and pressure. Includes information on obtaining the program and its documentation.…

Therapeutic effect of forearm low level light treatment on blood flow, oxygenation, and oxygen consumption

Science.gov (United States)

Wang, Pengbo; Sun, Jiajing; Meng, Lingkang; Li, Zebin; Li, Ting

2018-02-01

Low level light/laser therapy (LLLT) is considered as a novel, non-invasive, and potential therapy in a variety of psychological and physical conditions, due to its effective intricate photobiomodulation. The mechanism of LLLT is that when cells are stimulated by photons, mitochondria produce a large quantity of ATP, which accelerates biochemical responses in the cell. It is of great significance to gain a clear insight into the change or interplay of various physiological parameters. In this study, we used functional near-infrared spectroscopy (fNIRS) and venous-occlusion plethysmography to measure the LLLT-induced changes in blood flow, oxygenation, and oxygen consumption in human forearms in vivo. Six healthy human participants (4 males and 2 females) were administered with 810-nm light emitted by LED array in ten minutes and blood flow, oxygenation and oxygen consumption were detected in the entire experiment. We found that LLLT induced an increase of blood flow and oxygen consumption on the treated site. Meanwhile, LLLT took a good role in promoting oxygenation of regional tissue, which was indicated by a significant increase of oxygenated hemoglobin concentration (Δ[HbO2]), a nearly invariable deoxygenated hemoglobin concentration (Δ[Hb]) and a increase of differential hemoglobin concentration (Δ[HbD] = Δ[HbO2] - Δ[Hb]). These results not only demonstrate enormous potential of LLLT, but help to figure out mechanisms of photobiomodulation.

Suppression of aqueous corrosion of La(Fe0.88Si0.12)13 by reducing dissolved oxygen concentration for high-performance magnetic refrigeration

International Nuclear Information System (INIS)

Fujieda, S.; Fukamichi, K.; Suzuki, S.

2014-01-01

Highlights: • The aqueous corrosion of La(Fe 0.88 Si 0.12 ) 13 and its suppression were investigated. • The lattice expansion after immersion was caused by the hydrogen absorption. • The itinerant-electron metamagnetic transition became indistinct after immersion. • The aqueous corrosion was suppressed by reducing the dissolved oxygen concentration. - Abstract: The itinerant-electron metamagnetic transition of La(Fe 0.88 Si 0.12 ) 13 becomes indistinct after immersion in distilled-water containing about 8 ppm of the dissolved oxygen (DO) concentration because of aqueous corrosion. However, the aqueous corrosion of La(Fe 0.88 Si 0.12 ) 13 is significantly suppressed by reducing the DO concentration. Thus, isothermal magnetic entropy change after immersion for 30 days in deaerated distilled-water with a DO concentration less than 0.1 ppm is larger than that after immersion for 5 days in distilled-water containing about 8 ppm of the DO concentration. Consequently, the reduction of the DO concentration is effective for preservation of the excellent magnetocaloric effects of La(Fe 0.88 Si 0.12 ) 13 in an aqueous solution, which is a promising heat transfer fluid of room-temperature magnetic refrigeration

Oxygen regulation of nitrate uptake in denitrifying Pseudomonas aeruginosa.

OpenAIRE

Hernandez, D; Rowe, J J

1987-01-01

Oxygen had an immediate and reversible inhibitory effect on nitrate respiration by denitrifying cultures of Pseudomonas aeruginosa. Inhibition of nitrate utilization by oxygen appeared to be at the level of nitrate uptake, since nitrate reduction to nitrite in cell extracts was not affected by oxygen. The degree of oxygen inhibition was dependent on the concentration of oxygen, and increasing nitrate concentrations could not overcome the inhibition. The inhibitory effect of oxygen was maximal...

Alarm points for fixed oxygen monitors

International Nuclear Information System (INIS)

Miller, G.C.

1987-05-01

Oxygen concentration monitors were installed in a vault where numerous pipes carried inert cryogens and gases to the Mirror Fusion Test Facility (MFTF-B) experimental vessel at Lawrence Livermore National Laboratory (LLNL). The problems associated with oxygen-monitoring systems and the reasons why such monitors were installed were reviewed. As a result of this review, the MFTF-B monitors were set to sound an evacuation alarm when the oxygen concentration fell below 18%. We chose the 18% alarm criterion to minimize false alarms and to allow time for personnel to escape in an oxygen-deficient environment

Effect of tin doping on oxygen- and carbon-related defects in Czochralski silicon

International Nuclear Information System (INIS)

Chroneos, A.; Londos, C. A.; Sgourou, E. N.

2011-01-01

Experimental and theoretical techniques are used to investigate the impact of tin doping on the formation and the thermal stability of oxygen- and carbon-related defects in electron-irradiated Czochralski silicon. The results verify previous reports that Sn doping reduces the formation of the VO defect and suppresses its conversion to the VO 2 defect. Within experimental accuracy, a small delay in the growth of the VO 2 defect is observed. Regarding carbon-related defects, it is determined that Sn doping leads to a reduction in the formation of the C i O i , C i C s , and C i O i (Si I ) defects although an increase in their thermal stability is observed. The impact of strain induced in the lattice by the larger tin substitutional atoms, as well as their association with intrinsic defects and carbon impurities, can be considered as an explanation to account for the above observations. The density functional theory calculations are used to study the interaction of tin with lattice vacancies and oxygen- and carbon-related clusters. Both experimental and theoretical results demonstrate that tin co-doping is an efficient defect engineering strategy to suppress detrimental effects because of the presence of oxygen- and carbon-related defect clusters in devices.

Oxygenation and cracking in melt-textured YBCO bulk superconductors

International Nuclear Information System (INIS)

Kracunovska, S; Diko, P; Litzkendorf, D; Habisreuther, T; Bierlich, J; Gawalek, W

2005-01-01

Microstructural changes during the oxygenation of YBCO bulks were studied. It was shown that a lower temperature of oxygenation leads to the formation of a denser structure of a/b- and c-macrocracks and causes faster and more homogeneous oxygenation of the sample. The opening of created macrocracks is the way in which the macroscopic stresses induced by macroscopic 211 particle concentration inhomogeneity are released. This is very important, because it prevents the formation of fatal c-macrocracks, which divide the sample into more domains, during cooling from oxygenation temperature or during sample performance. Oxygenation with a multistage programme causes the oxygen concentration difference between the oxygenated layer and the tetragonal matrix to be smaller, and consequently fewer macrocracks are formed. This leads to the prolongation of oxygenation times for full oxygenation and to the insufficient release of macroscopic stresses. 211 low concentration regions and pores also enhance the oxygenation rate of YBCO bulks

Cell physiology regulation by hypoxia inducible factor-1: Targeting oxygen-related nanomachineries of hypoxic cells.

Science.gov (United States)

Eskandani, Morteza; Vandghanooni, Somayeh; Barar, Jaleh; Nazemiyeh, Hossein; Omidi, Yadollah

2017-06-01

Any dysfunctionality in maintaining the oxygen homeostasis by mammalian cells may elicit hypoxia/anoxia, which results in inescapable oxidative stress and possible subsequent detrimental impacts on certain cells/tissues with high demands to oxygen molecules. The ischemic damage in turn can trigger initiation of a number of diseases including organs ischemia, metabolic disorders, inflammatory diseases, different types of malignancies, and alteration in wound healing process. Thus, full comprehension of molecular mechanism(s) and cellular physiology of the oxygen homeostasis is the cornerstone of the mammalian cells metabolism, energetic pathways and health and disease conditions. An imbalance in oxygen content within the cellular microenvironment activates a cascade of molecular events that are often compensated, otherwise pathologic condition occurs through a complexed network of biomolecules. Hypoxia inducible factor-1 (HIF-1) plays a key transcriptional role in the adaptation of cell physiology in relation with the oxygen content within a cell. In this current study, we provide a comprehensive review on the molecular mechanisms of oxygen sensing and homeostasis and the impacts of HIF-1 in hypoxic/anoxic conditions. Moreover, different molecular and biochemical responses of the cells to the surrounding environment are discussed in details. Finally, modern technological approaches for targeting the hypoxia related proteins are articulated. Copyright © 2017. Published by Elsevier B.V.

Mixed oxygen ion/electron-conducting ceramics for oxygen separation

Energy Technology Data Exchange (ETDEWEB)

Stevenson, J.W.; Armstrong, T.R.; Armstrong, B.L. [Pacific Northwest National Lab., Richland, WA (United States)

1996-08-01

Mixed oxygen ion and electron-conducting ceramics are unique materials that can passively separate high purity oxygen from air. Oxygen ions move through a fully dense ceramic in response to an oxygen concentration gradient, charge-compensated by an electron flux in the opposite direction. Compositions in the system La{sub 1{minus}x}M{sub x}Co{sub 1{minus}y{minus}z}Fe{sub y}N{sub z}O{sub 3{minus}{delta}}, perovskites where M=Sr, Ca, and Ba, and N=Mn, Ni, Cu, Ti, and Al, have been prepared and their electrical, oxygen permeation, oxygen vacancy equilibria, and catalytic properties evaluated. Tubular forms, disks, and asymmetric membrane structures, a thin dense layer on a porous support of the same composition, have been fabricated for testing purposes. In an oxygen partial gradient, the passive oxygen flux through fully dense structures was highly dependent on composition. An increase in oxygen permeation with increased temperature is attributed to both enhanced oxygen vacancy mobility and higher vacancy populations. Highly acceptor-doped compositions resulted in oxygen ion mobilities more than an order of magnitude higher than yttria-stabilized zirconia. The mixed conducting ceramics have been utilized in a membrane reactor configuration to upgrade methane to ethane and ethylene. Conditions were established to balance selectivity and throughput in a catalytic membrane reactor constructed from mixed conducting ceramics.

Optical measurements of atomic oxygen concentration, temperature and nitric oxide production rate in flames

Science.gov (United States)

Myhr, Franklin Henry

An optical method for measuring nitric oxide (NO) production rates in flames was developed and characterized in a series of steady, one-dimensional, atmospheric-pressure laminar flames of 0.700 Hsb2/0.199 Nsb2/0.101 COsb2 or 0.700 CHsb4/0.300 Nsb2 (by moles) with dry air, with equivalence ratios from 0.79 to 1.27. Oxygen atom concentration, (O), was measured by two-photon laser-induced fluorescence (LIF), temperature was measured by ultraviolet Rayleigh scattering, and nitrogen concentration was calculated from supplied reactant flows; together this information was used to calculate the NO production rate through the thermal (Zel'dovich) mechanism. Measurements by two other techniques were compared with results from the above method. In the first comparison, gas sampling was used to measure axial NO concentration profiles, the slopes of which were multiplied by velocity to obtain total NO production rates. In the second comparison, LIF measurements of hydroxyl radical (OH) were used with equilibrium water concentrations and a partial equilibrium assumption to find (O). Nitric oxide production rates from all three methods agreed reasonably well. Photolytic interference was observed during (O) LIF measurements in all of the flames; this is the major difficulty in applying the optical technique. Photolysis of molecular oxygen in lean flames has been well documented before, but the degree of interference observed in the rich flames suggests that some other molecule is also dissociating; the candidates are OH, CO, COsb2 and Hsb2O. An extrapolative technique for removing the effects of photolysis from (O) LIF measurements worked well in all flames where NO production was significant. Using the optical method to measure NO production rates in turbulent flames will involve a tradeoff among spatial resolution, systematic photolysis error, and random shot noise. With the conventional laser system used in this work, a single pulse with a resolution of 700 mum measured NO

Effects of inoculum type and bulk dissolved oxygen concentration on achieving partial nitrification by entrapped-cell-based reactors.

Science.gov (United States)

Rongsayamanont, Chaiwat; Limpiyakorn, Tawan; Khan, Eakalak

2014-07-01

An entrapment of nitrifiers into gel matrix is employed as a tool to fulfill partial nitrification under non-limiting dissolved oxygen (DO) concentrations in bulk solutions. This study aims to clarify which of these two attributes, inoculum type and DO concentration in bulk solutions, is the decisive factor for partial nitrification in an entrapped-cell based system. Four polyvinyl alcohol entrapped inocula were prepared to have different proportions of nitrite-oxidizing bacteria (NOB) and nitrite-oxidizing activity. At a DO concentration of 3 mg l(-1), the number of active NOB cells in an inoculum was the decisive factor for partial nitrification enhancement. However, when the DO concentration was reduced to 2 mg l(-1), all entrapped cell inocula showed similar degrees of partial nitrification. The results suggested that with the lower bulk DO concentration, the preparation of entrapped cell inocula is not useful as the DO level becomes the decisive factor for achieving partial nitrification. Copyright © 2014 Elsevier Ltd. All rights reserved.

Relative effectiveness of ionizing radiations in relation to LET and the influence of oxygen

International Nuclear Information System (INIS)

Barendsen, G.W.

1966-01-01

phenomena in terms of a specific model is its potentiality to account for the modification of radiation-induced effects by protecting and potentiating agents. It has been demonstrated with various systems that cells in anoxic conditions are less sensitive to ionizing radiations than oxygenated cells. In addition, it has been observed that this enhancing action of oxygen depends on the type of ionizing radiation used and generally decreases with increasing LET. The present contribution describes a comparison and analysis of the RBE- LET relations for impairment of the proliferative capacity of cultured human cells irradiated in oxygenated and anoxic conditions

Steady-state oxygen-solubility in niobium

International Nuclear Information System (INIS)

Schulze, K.; Jehn, H.

1977-01-01

During annealing of niobium in oxygen in certain temperature and pressure ranges steady states are established between the absorption of molecular oxygen and the evaporation of volatile oxides. The oxygen concentration in the niobium-oxygen α-solid solution is a function of oxygen pressure and temperature and has been redetermined in the ranges 10 -5 - 10 -2 Pa O 2 and 2,070 - 2,470 K. It follows differing from former results the equation csub(o) = 9.1 x 10 -6 x sub(po2) x exp (502000/RT) with csub(o) in at.-ppm, sub(po2) in Pa, T in K, R = 8.31 J x mol -1 x K -1 . The existence of steady states is limited to a temperature range from 1870 to 2470 K and to oxygen concentrations below the solubility limit given by solidus and solvus lines in the T-c diagram. In the experiments high-purity niobium wires with a specific electrical ratio rho (273 K)/rho(4.2 K) > 5,000 have been gassed under isothermal-isobaric conditions until the steady state has been reached. The oxygen concentration has been determined analytically by vacuum fusion extraction with platinum-flux technique as well as by electrical residual resistivity measurements at 4.2 K. (orig.) [de

Correlated lifetimes of free paraexcitons and excitons trapped at oxygen vacancies in cuprous oxide

International Nuclear Information System (INIS)

Koirala, Sandhaya; Naka, Nobuko; Tanaka, Koichiro

2013-01-01

We have studied transients of luminescence due to free excitons and excitons trapped at oxygen vacancies in cuprous oxide. We find that both trapped and free paraexcitons have lifetime dependent on temperature and on the oxygen concentration. By using samples containing much less copper vacancies relative to oxygen vacancies, we find out the direct correlation between the free paraexciton lifetime and trapped exciton lifetime. - Highlights: ► We have investigated trapping of free excitons at oxygen vacancies in cuprous oxide. ► Lifetimes of free and trapped excitons exhibit correlative temperature dependence. ► Four-level model with the activation energy of 33 meV well explains the observation. ► Comparison is made using the four samples with different vacancy concentrations. ► We clarified the crucial role of the oxygen vacancy in shortening the lifetimes.

Should direct measurements of tumor oxygenation relate to the radiobiological hypoxic fraction of a tumor?

International Nuclear Information System (INIS)

Fenton, Bruce M.; Kiani, Mohammad F.; Siemann, Dietmar W.

1995-01-01

Purpose: Numerous previous studies have attempted to relate the radiobiological hypoxic fraction (HF) to direct measures of tumor oxygenation such as HbO 2 saturations, tumor pO 2 levels, or hypoxic cell labeling. Although correlations have been found within tumor lines, no overall relationships were seen across tumor lines. The current objective was to examine the effect on HF of changes in the fractions of the oxygenated and anoxic tumor cells that remain clonogenic. Methods and Materials: A mathematical model was developed that relates the HF to direct measures of tumor oxygenation. The primary assumptions were that: (a) the tumor is divided into distinct compartments of either fully oxygenated or fully anoxic cells, and (b) the survival of the oxygenated cells is negligible compared to that of the anoxic cells. Based on these assumptions, the HF is plotted as a function of the fractions of clonogenic or nonclonogenic, and oxygenated or anoxic cells. Results: If all cells are clonogenic, then the HF equals the fraction of anoxic cells. If a higher fraction of anoxic than oxygenated cells are nonclonogenic, then the HF will be overestimated by the fraction of the tumor measured to be anoxic using direct measuring techniques. If a higher fraction of the oxygenated than anoxic cells are nonclonogenic, the HF will be underestimated by the fraction of anoxic cells. Conclusion: Correlations between the HF and direct measures of tumor oxygenation have been described within tumor lines evaluated under different physiological condition. However, such relationships can be totally unpredictable between different tumors if the fraction of the anoxic cells that is clonogenic varies substantially. Clearly, if tumor anoxia cannot be detected using direct measures, this is an accurate indication that the tumor is well oxygenated. When tumor anoxia is present, however, the conclusions are ambiguous. Even when a small fraction of the tumor is measured as anoxic, direct measures

Controlling factors of the oxygen balance in the Arabian Sea's OMZ

Directory of Open Access Journals (Sweden)

L. Resplandy

2012-12-01

Full Text Available The expansion of OMZs (oxygen minimum zones due to climate change and their possible evolution and impacts on the ecosystems and the atmosphere are still debated, mostly because of the unability of global climate models to adequatly reproduce the processes governing OMZs. In this study, we examine the factors controlling the oxygen budget, i.e. the equilibrium between oxygen sources and sinks in the northern Arabian Sea OMZ using an eddy-resolving biophysical model.

Our model confirms that the biological consumption of oxygen is most intense below the region of highest productivity in the western Arabian Sea. The oxygen drawdown in this region is counterbalanced by the large supply of oxygenated waters originated from the south and advected horizontally by the western boundary current. Although the biological sink and the dynamical sources of oxygen compensate on annual average, we find that the seasonality of the dynamical transport of oxygen is 3 to 5 times larger than the seasonality of the biological sink. In agreement with previous findings, the resulting seasonality of oxygen concentration in the OMZ is relatively weak, with a variability of the order of 15% of the annual mean oxygen concentration in the oxycline and 5% elsewhere. This seasonality primarily arises from the vertical displacement of the OMZ forced by the monsoonal reversal of Ekman pumping across the basin. In coastal areas, the oxygen concentration is also modulated seasonally by lateral advection. Along the western coast of the Arabian Sea, the Somali Current transports oxygen-rich waters originated from the south during summer and oxygen-poor waters from the northeast during winter. Along the eastern coast of the Arabian Sea, we find that the main contributor to lateral advection in the OMZ is the Indian coastal undercurrent that advects southern oxygenated waters during summer and northern low-oxygen waters during winter. In this region, our model indicates that

Characterization of water quality and simulation of temperature, nutrients, biochemical oxygen demand, and dissolved oxygen in the Wateree River, South Carolina, 1996-98

Science.gov (United States)

Feaster, Toby D.; Conrads, Paul

2000-01-01

In May 1996, the U.S. Geological Survey entered into a cooperative agreement with the Kershaw County Water and Sewer Authority to characterize and simulate the water quality in the Wateree River, South Carolina. Longitudinal profiling of dissolved-oxygen concentrations during the spring and summer of 1996 revealed dissolved-oxygen minimums occurring upstream from the point-source discharges. The mean dissolved-oxygen decrease upstream from the effluent discharges was 2.0 milligrams per liter, and the decrease downstream from the effluent discharges was 0.2 milligram per liter. Several theories were investigated to obtain an improved understanding of the dissolved-oxygen dynamics in the upper Wateree River. Data suggest that the dissolved-oxygen concentration decrease is associated with elevated levels of oxygen-consuming nutrients and metals that are flowing into the Wateree River from Lake Wateree. Analysis of long-term streamflow and water-quality data collected at two U.S. Geological Survey gaging stations suggests that no strong correlation exists between streamflow and dissolved-oxygen concentrations in the Wateree River. However, a strong negative correlation does exist between dissolved-oxygen concentrations and water temperature. Analysis of data from six South Carolina Department of Health and Environmental Control monitoring stations for 1980.95 revealed decreasing trends in ammonia nitrogen at all stations where data were available and decreasing trends in 5-day biochemical oxygen demand at three river stations. The influence of various hydrologic and point-source loading conditions on dissolved-oxygen concentrations in the Wateree River were determined by using results from water-quality simulations by the Branched Lagrangian Transport Model. The effects of five tributaries and four point-source discharges were included in the model. Data collected during two synoptic water-quality samplings on June 23.25 and August 11.13, 1997, were used to calibrate

Study of oxygen mass transfer coefficient and oxygen uptake rate in a stirred tank reactor for uranium ore bioleaching

International Nuclear Information System (INIS)

Zokaei-Kadijani, S.; Safdari, J.; Mousavian, M.A.; Rashidi, A.

2013-01-01

Highlights: ► Mass transfer coefficient does not depend on biomass concentration. ► The pulp density has a negative effect on mass transfer coefficient. ► The pulp density is the unique factor that affects maximum OUR. ► In this work, Neale’s correlation is corrected for prediction of mass transfer coefficient. ► Biochemical reaction is a limiting factor in the uranium bioleaching process. - Abstract: In this work, the volumetric oxygen mass transfer coefficient and the oxygen uptake rate (OUR) were studied for uranium ore bioleaching process by Acidthiobacillus ferrooxidans in a stirred tank reactor. The Box-Bohnken design method was used to study the effect of operating parameters on the oxygen mass transfer coefficient. The investigated factors were agitation speed (rpm), aeration rate (vvm) and pulp density (% weight/volume) of the stirred tank reactor. Analysis of experimental results showed that the oxygen mass transfer coefficient had low dependence on biomass concentration but had higher dependence on the agitation speed, aeration rate and pulp density. The obtained biological enhancement factors were equal to ones in experiments. On the other hand, the obtained values for Damkohler number (Da < 0.468) indicated that the process was limited by the biochemical reaction rate. Experimental results obtained for oxygen mass transfer coefficient were correlated with the empirical relations proposed by Garcia-Ochoa and Gomez (2009) and Neale and Pinches (1994). Due to the high relative error in the correlation of Neale and Pinches, that correlation was corrected and the coefficient of determination was calculated to be 89%. The modified correlation has been obtained based on a wide range of operating conditions, which can be used to determine the mass transfer coefficient in a bioreactor

Determination of respiration rates in water with sub-micromolar oxygen concentrations

Directory of Open Access Journals (Sweden)

Emilio Garcia-Robledo

2016-11-01

Full Text Available It is crucial for our study and understanding of element transformations in low-oxygen waters that we are able to reproduce the in situ conditions during laboratory incubations to an extent that does not result in unacceptable artefacts. In this study we have explored how experimental conditions affect measured rates of O2 consumption in low-O2 waters from the anoxic basin of Golfo Dulce (Costa Rica and oceanic waters off Chile-Peru. High-sensitivity optode dots placed within all-glass incubation containers allowed for high resolution O2 concentration measurements in the nanomolar and low µmolar range and thus also for the determination of rates of oxygen consumption by microbial communities. Consumption rates increased dramatically (from 3 and up to 60 times by prolonged incubations, and started to increase after 4-5 hours in surface waters and after 10-15 h in water from below the upper mixed layer. Estimated maximum growth rates during the incubations suggest the growth of opportunistic microorganism with doubling times as low as 2.8 and 4.6 h for the coastal waters of Golfo Dulce (Costa Rica and oceanic waters off Chile and Peru, respectively. Deoxygenation by inert gas bubbling led to increases in subsequently determined rates, possibly by liberation of organics from lysis of sensitive organisms, particle or aggregate alterations or other processes mediated by the strong turbulence. Stirring of the water during the incubation led to an about 50% increase in samples previously deoxygenated by bubbling, but had no effect in untreated samples. Our data indicate that data for microbial activity obtained by short incubations of minimally manipulated water are most reliable, but deoxygenation is a prerequisite for many laboratory experiments, such as determination of denitrification rates, as O2 contamination by sampling is practically impossible to avoid.

VASCULAR PLANTS AS ENGINEERS OF OXYGEN IN AQUATIC SYSTEMS

Science.gov (United States)

The impact of organisms on oxygen is one of the most dramatic examples of ecosystem engineering on Earth. In aquatic systems, which have much lower oxygen concentrations than the atmosphere, vascular aquatic plants can affect oxygen concentrations significantly not only on long t...

Yeast alter micro-oxygenation of wine: oxygen consumption and aldehyde production.

Science.gov (United States)

Han, Guomin; Webb, Michael R; Richter, Chandra; Parsons, Jessica; Waterhouse, Andrew L

2017-08-01

Micro-oxygenation (MOx) is a common winemaking treatment used to improve red wine color development and diminish vegetal aroma, amongst other effects. It is commonly applied to wine immediately after yeast fermentation (phase 1) or later, during aging (phase 2). Although most winemakers avoid MOx during malolactic (ML) fermentation, it is often not possible to avoid because ML bacteria are often present during phase 1 MOx treatment. We investigated the effect of common yeast and bacteria on the outcome of micro-oxygenation. Compared to sterile filtered wine, Saccharomyces cerevisiae inoculation significantly increased oxygen consumption, keeping dissolved oxygen in wine below 30 µg L -1 during micro-oxygenation, whereas Oenococcus oeni inoculation was not associated with a significant impact on the concentration of dissolved oxygen. The unfiltered baseline wine also had both present, although with much higher populations of bacteria and consumed oxygen. The yeast-treated wine yielded much higher levels of acetaldehyde, rising from 4.3 to 29 mg L -1 during micro-oxygenation, whereas no significant difference was found between the bacteria-treated wine and the filtered control. The unfiltered wine exhibited rapid oxygen consumption but no additional acetaldehyde, as well as reduced pyruvate. Analysis of the acetaldehyde-glycerol acetal levels showed a good correlation with acetaldehyde concentrations. The production of acetaldehyde is a key outcome of MOx and it is dramatically increased in the presence of yeast, although it is possibly counteracted by the metabolism of O. oeni bacteria. Additional controlled experiments are necessary to clarify the interaction of yeast and bacteria during MOx treatments. Analysis of the glycerol acetals may be useful as a proxy for acetaldehyde levels. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

The effect of temperature and oxygen content on coal burnout

Energy Technology Data Exchange (ETDEWEB)

K. Milenkova; A.G. Borrego; D. Alvarez; J. Xiberta; R. Menendez [Instituto Nacional del Carbon, CSIC, Oviedo (Spain)

2003-07-01

In this study chars from six coals differing in rank and maceral composition have been prepared at 1100 and 1300{sup o}C in a drop tube reactor using four oxygen concentrations (0, 2.5, 10 and 21% oxygen). Char burnout, reactivity, morphology and optical texture have been considered in an attempt to understand the effect of temperature and oxygen concentration in relation to coal characteristics. Temperature has shown to have a different effect on conversion depending on coal rank. The high volatile coals showed similar conversions at 1100 and 1300{sup o}C at the various atmospheres tested, whereas higher rank coals showed higher conversions at 1300 than at 1100{sup o}C. The presence of oxygen in the reacting gas appears to have two opposite effects on coal combustion. On the one hand it prevents swelling and devolatilisation and on the other it enhances combustion. The burnout will depend on which process dominates. In addition, this effect appears to be temperature dependant and the inhibiting effect of oxygen on coal devolatilisation has shown to be higher at higher temperature, since at low temperature it only affects the lowest ranked coals. The presence of oxygen also affects the structure of carbonaceous material since the lower the oxygen concentration the higher the anisotropy development. The difference in temperature separating the two series of experiments (1000 and 1300{sup o}C) did not have a positive effect on the conversion of coals yielding highly porous chars whereas for coals yielding more dense structures higher conversions were achieved at higher temperatures. 7 refs., 5 figs., 1 tab.

Multi-regional investigation of the relationship between functional MRI blood oxygenation level dependent (BOLD activation and GABA concentration.

Directory of Open Access Journals (Sweden)

Ashley D Harris

Full Text Available Several recent studies have reported an inter-individual correlation between regional GABA concentration, as measured by MRS, and the amplitude of the functional blood oxygenation level dependent (BOLD response in the same region. In this study, we set out to investigate whether this coupling generalizes across cortex. In 18 healthy participants, we performed edited MRS measurements of GABA and BOLD-fMRI experiments using regionally related activation paradigms. Regions and tasks were the: occipital cortex with a visual grating stimulus; auditory cortex with a white noise stimulus; sensorimotor cortex with a finger-tapping task; frontal eye field with a saccade task; and dorsolateral prefrontal cortex with a working memory task. In contrast to the prior literature, no correlation between GABA concentration and BOLD activation was detected in any region. The origin of this discrepancy is not clear. Subtle differences in study design or insufficient power may cause differing results; these and other potential reasons for the discrepant results are discussed. This negative result, although it should be interpreted with caution, has a larger sample size than prior positive results, and suggests that the relationship between GABA and the BOLD response may be more complex than previously thought.

Geographic variation in long-term oxygen therapy in Denmark : factors related to adherence to guidelines for long-term oxygen therapy

DEFF Research Database (Denmark)

Ringbæk, Thomas Jørgen; Lange, Peter; Viskum, K

2001-01-01

STUDY OBJECTIVES: To evaluate regional differences in adherence to guidelines for long-term oxygen therapy (LTOT) in Denmark and to determine factors related to compliance with these guidelines. DESIGN: Cross-sectional study and analysis of a nationwide database (Danish Oxygen Register). SETTING...... to national guidelines for LTOT was found in 34.4% of the patients for the whole of Denmark and varied regionally from 14 to 63%. Mean compliance with guidelines was 5.3 (range, 2.9 to 9.1) times as likely if the oxygen was prescribed by a pulmonary department compared to LTOT initiated by a GP. CONCLUSIONS......: Marked geographic variations in compliance with LTOT guidelines are present even in a small country as Denmark. In general, the adherence to the guidelines is poor, especially when non-chest physicians prescribe LTOT. We therefore recommend that local and national thoracic societies together with health...

Theoretical analysis of ozone generation by pulsed dielectric barrier discharge in oxygen

Science.gov (United States)

Wei, L. S.; Zhou, J. H.; Wang, Z. H.; Cen, K. F.

2007-08-01

The use of very short high-voltage pulses combined with a dielectric layer results in high-energy electrons that dissociate oxygen molecules into atoms, which are a prerequisite for the subsequent production of ozone by collisions with oxygen molecules and third particles. The production of ozone depends on both the electrical and the physical parameters. For ozone generation by pulsed dielectric barrier discharge in oxygen, a mathematical model, which describes the relation between ozone concentration and these parameters that are of importance in its design, is developed according to dimensional analysis theory. A formula considering the ozone destruction factor is derived for predicting the characteristics of the ozone generation, within the range of the corona inception voltage to the gap breakdown voltage. The trend showing the dependence of the concentration of ozone in oxygen on these parameters generally agrees with the experimental results, thus confirming the validity of the mathematical model.

Variability and Dynamics of Dissolved Oxygen in the Transition Zone of the North Sea and the Baltic Sea

DEFF Research Database (Denmark)

Jonasson, Lars

information about the seasonal to decadal oxygen variations in the bottom water of the Kattegat, the Danish Straits, the Sound and the Western Baltic Sea and investigates the relative importance of physical and biogeochemical processes, climate change and nutrient load reductions on the oxygen variability......The bottom water in the transition zone of the North Sea and Baltic Sea suffers from seasonal hypoxia, usually during late summer and autumn. Hypoxia is a natural phenomenon in this region because of the strong vertical stratification which prevents the bottom water to be ventilated by atmospheric...... concentrations by 15-30 μmol O2 l−1 yr−1 while the reduced nutrient concentration has increased the oxygen concentration with approximately the same amount. Thus, the positive effect on oxygen conditions from reduced nutrient concentrations have been counteracted by increased water temperatures. This has made...

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

International Nuclear Information System (INIS)

Helm, Irja; Jalukse, Lauri; Leito, Ivo

2012-01-01

Highlights: ► Probably the most accurate method available for dissolved oxygen concentration measurement was developed. ► Careful analysis of uncertainty sources was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. ► This development enables more accurate calibration of dissolved oxygen sensors for routine analysis than has been possible before. - Abstract: A high-accuracy Winkler titration method has been developed for determination of dissolved oxygen concentration. Careful analysis of uncertainty sources relevant to the Winkler method was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. The most important improvements were: gravimetric measurement of all solutions, pre-titration to minimize the effect of iodine volatilization, accurate amperometric end point detection and careful accounting for dissolved oxygen in the reagents. As a result, the developed method is possibly the most accurate method of determination of dissolved oxygen available. Depending on measurement conditions and on the dissolved oxygen concentration the combined standard uncertainties of the method are in the range of 0.012–0.018 mg dm −3 corresponding to the k = 2 expanded uncertainty in the range of 0.023–0.035 mg dm −3 (0.27–0.38%, relative). This development enables more accurate calibration of electrochemical and optical dissolved oxygen sensors for routine analysis than has been possible before.

Theory of oxygen isotope exchange

NARCIS (Netherlands)

den Otter, M.W.; Boukamp, Bernard A.; Bouwmeester, Henricus J.M.

2001-01-01

Transients for oxygen molecular mass numbers 32, 34 and 36 are derived which can be used for the interpretation of oxygen isotope exchange data based on measurement of concentrations of 16O2, 16O18O and 18O2 in the gas phase. Key parameters in the theory are the rate at which oxygen molecules are

A Low-Pressure Oxygen Storage System for Oxygen Supply in Low-Resource Settings.

Science.gov (United States)

Rassool, Roger P; Sobott, Bryn A; Peake, David J; Mutetire, Bagayana S; Moschovis, Peter P; Black, Jim Fp

2017-12-01

Widespread access to medical oxygen would reduce global pneumonia mortality. Oxygen concentrators are one proposed solution, but they have limitations, in particular vulnerability to electricity fluctuations and failure during blackouts. The low-pressure oxygen storage system addresses these limitations in low-resource settings. This study reports testing of the system in Melbourne, Australia, and nonclinical field testing in Mbarara, Uganda. The system included a power-conditioning unit, a standard oxygen concentrator, and an oxygen store. In Melbourne, pressure and flows were monitored during cycles of filling/emptying, with forced voltage fluctuations. The bladders were tested by increasing pressure until they ruptured. In Mbarara, the system was tested by accelerated cycles of filling/emptying and then run on grid power for 30 d. The low-pressure oxygen storage system performed well, including sustaining a pressure approximately twice the standard working pressure before rupture of the outer bag. Flow of 1.2 L/min was continuously maintained to a simulated patient during 30 d on grid power, despite power failures totaling 2.9% of the total time, with durations of 1-176 min (mean 36.2, median 18.5). The low-pressure oxygen storage system was robust and durable, with accelerated testing equivalent to at least 2 y of operation revealing no visible signs of imminent failure. Despite power cuts, the system continuously provided oxygen, equivalent to the treatment of one child, for 30 d under typical power conditions for sub-Saharan Africa. The low-pressure oxygen storage system is ready for clinical field trials. Copyright © 2017 by Daedalus Enterprises.

Interaction of nitroimidazole sensitizers and oxygen in the radiosensitization of mammalian cells at ultrahigh dose rates

International Nuclear Information System (INIS)

Michaels, H.B.; Ling, C.C.; Epp, E.R.; Peterson, E.C.

1981-01-01

When CHO cells, equilibrated with 0.44% oxygen, are irradiated with single 3-nsec pulses of electrons from a 600-kV-field emission source, a breaking survival curve is observed. The breaking behavior, believed to be the result of radiolytic oxygen depletion, can be prevented by the presence of a relatively low concentration of the hypoxic cell sensitizer misonidazole; similar results are obtained with metronidazole and Ro-05-9963. The resulting survival curves exhibit a sensitized response similar to that obtained with conventional dose rate radiation for CHO cells under this oxygen concentration. This degree of sensitization is greater than that observed for CHO cells irradiated at ultrahigh dose rates under the same concentration of sensitizer in nitrogen. The data suggest that the nitroimidazole compounds interfere with the radiation chemical oxygen depletion process and that the radiosensitization observed in the nonbreaking survival curve is the consequence of sensitization by both the nitroimidazole and, primarily, the oxygen rather than a direct subsitution for oxygen by the sensitizer. This conclusion is also supported by data obtained in double-pulse experiments. The results are discussed with regard to the mechanisms of the oxygen depletion process and radiosensitization

The effect of chlorine and oxygen concentrations on the removal of mercury at an FGD-batch reactor

Energy Technology Data Exchange (ETDEWEB)

Carolina Acuna-Caro; Kevin Brechtel; Guenter Scheffknecht; Manuel Brass [University of Stuttgart, Stuttgart (Germany). Institute of Process Engineering and Power Plant Technology (IVD)

2009-12-15

A series of laboratory scale experiments were conducted in an FGD-batch reactor. A synthetic flue gas was produced and directed through a CaCO{sub 3} suspension contained in a glass reactor vessel. The suspension temperature was set at 54{sup o}C through a water bath. In order to observe the distribution of mercury species in the system, solid, liquid and gaseous samples were taken and analysed. For gaseous mercury determination, continuous measurements were carried out, up and downstream the reactor. Furthermore, the concentration of chlorine in the scrubber solution of the system was varied from 0 to 62 g/l under different oxidative conditions. In a first approach, a concentration drop of elemental mercury coming out of the system was observed. The latter occurs only when high concentrations of Cl{sup -} are present, combined with a high O{sub 2} availability in the scrubber. It was also observed that mercury species distribution in the different phases varies, depending on the available chemical form of chlorine and oxygen concentration. 14 refs., 7 figs., 1 tab.

Effects of the Oxygenation level on Formation of Different Reactive Oxygen Species During Photodynamic Therapy

OpenAIRE

Price, Michael; Heilbrun, Lance; Kessel, David

2013-01-01

We examined the effect of the oxygenation level on efficacy of two photosensitizing agents, both of which target lysosomes for photodamage but via different photochemical pathways. Upon irradiation, the chlorin termed NPe6 forms singlet oxygen in high yield while the bacteriopheophorbide WST11 forms only oxygen radicals (in an aqueous environment). Photokilling efficacy by WST11 in cell culture was impaired when the atmospheric oxygen concentration was reduced from 20% to 1%, while photokilli...

Mathematical modeling of dissolved oxygen in fish ponds

African Journals Online (AJOL)

TUOYO

A mathematical model was developed to predict the effects of wind speed, light, pH, Temperature, dissolved carbon dioxide .... chlorophyll, the energy obtained splits water, and oxygen ... is a function of temperature T, light L, substrate, and pH as shown in ..... plants and its relation to the concentration of carbon dioxide and.

Density functional theory investigation of oxygen interaction with boron-doped graphite

Energy Technology Data Exchange (ETDEWEB)

Liu, Juan; Wang, Chen [State Key Lab of New Ceramic and Fine Processing, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Liang, Tongxiang, E-mail: txliang@tsinghua.edu.cn [State Key Lab of New Ceramic and Fine Processing, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Lai, Wensheng [Advanced Material Laboratory, School of Materials Science & Engineering, Tsinghua University, Beijing, 100084 (China)

2016-12-30

Highlights: • Density-functional approach is applied to study the interaction of oxygen with boron-doped graphite. • Adsorption and diffusion of oxygen atoms on boron doped graphite surfaces are studied. • Recombination of oxygen is investigated by ER and LH mechanisms. • Low boron concentration facilitates O{sub 2} formation while high boron loading inhibits the recombination. • The presence of B−B bonds due to boron accumulation makes it impossible for oxygen recombination. - Abstract: Boron inserted as impurity by substitution of carbon atoms in graphite is known to change (improve or deteriorate) oxidation resistance of nuclear graphite, but the reason for both catalytic and inhibiting oxidation is still uncertain. As a first step, this work is more specially devoted to the adsorption and diffusion of oxygen atoms on the surface and related to the problem of oxygen retention on the pure and boron-containing graphite surfaces. Adsorption energies and energy barriers associated to the diffusion for molecular oxygen recombination are calculated in the density functional theory framework. The existence of boron modifies the electronic structure of the surface, which results in an increase of the adsorption energy for O. However, low boron loading makes it easier for the recombination into molecular oxygen. For high boron concentration, it induces a better O retention capability in graphite because the presence of B-B bonds decreases recombination of the adsorbed oxygen atoms. A possible explanation for both catalytic and inhibiting effects of boron in graphite is proposed.

Effects of drying methods on the low temperature reactivity of Victorian brown coal to oxygen

Energy Technology Data Exchange (ETDEWEB)

Unal, S.; Wood, D.G.; Harris, I.J. (University of Marmara, Istanbul (Turkey). Ataturk Faculty of Education, Division of Science Education)

1992-02-01

The effects of air drying and thermal dewatering on the low temperature oxygen reactivity of Victorian brown coal have been investigated in the temperature range 35-55{degree}C and at 100 kPa oxygen pressure using coal samples ground to {lt} 100 mesh. An attempt has also been made to relate the low temperature oxygen reactivity of the coal to its free radical concentration as measured prior to oxidation. Two rate models, the Schmidt and Winmill models, have been adapted to include the initial free radical concentration of the coal samples as the drying method sensitivity parameter in lieu of the concentration of oxygen-reactive sites in the coal material. The experimental results show that air drying, which reduces the free radical concentration of the coal, causes a decline in its oxygen reactivity whereas thermal dewatering, which causes an increase in the free radical concentration of the coal, enhances its oxygen reactivity. Air drying does not affect the distribution of the consumed oxygen in the oxidation products. A difference is observed in the case of the thermally dewatered coal samples. The correlation of the two rate models adopted is considered equally satisfactory. However, only the values obtained for the two activation energies in the Winmill model reflect the changes caused by thermal dewatering in the oxidation pattern of the coal. The activation energy values obtained from the two models are within the range of those quoted in the literature for the abstraction of hydrogen from various arene structures by free radicals. 35 refs., 10 figs., 8 tabs.

Oxygen and diverse nutrients influence the water kefir fermentation process.

Science.gov (United States)

Laureys, David; Aerts, Maarten; Vandamme, Peter; De Vuyst, Luc

2018-08-01

Eight water kefir fermentation series differing in the presence of oxygen, the nutrient concentration, and the nutrient source were studied during eight consecutive backslopping steps. The presence of oxygen allowed the proliferation of acetic acid bacteria, resulting in high concentrations of acetic acid, and decreased the relative abundance of Bifidobacterium aquikefiri. Low nutrient concentrations resulted in slow water kefir fermentation and high pH values, which allowed the growth of Comamonas testosteroni/thiooxydans. Further, low nutrient concentrations favored the growth of Lactobacillus hilgardii and Dekkera bruxellensis, whereas high nutrient concentrations favored the growth of Lactobacillus nagelii and Saccharomyces cerevisiae. Dried figs, dried apricots, and raisins resulted in stable water kefir fermentation. Water kefir fermentation with dried apricots resulted in the highest pH and water kefir grain growth, whereas that with raisins resulted in the lowest pH and water kefir grain growth. Further, water kefir fermentation with raisins resembled fermentations with low nutrient concentrations, that with dried apricots resembled fermentations with normal nutrient concentrations, and that with fresh figs or a mixture of yeast extract and peptone resembled fermentations with high nutrient concentrations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Oxygen and Perfusion Kinetics in Response to Fractionated Radiation Therapy in FaDu Head and Neck Cancer Xenografts Are Related to Treatment Outcome

Energy Technology Data Exchange (ETDEWEB)

Hu, Fangyao [Department of Biomedical Engineering, Duke University, Durham, North Carolina (United States); Vishwanath, Karthik [Department of Physics, Miami University, Oxford, Ohio (United States); Salama, Joseph K. [Department of Radiation Oncology, Duke University, Durham, North Carolina (United States); Division of Radiation Oncology, Veterans Administration Medical Center, Durham, North Carolina (United States); Erkanli, Alaattin; Peterson, Bercedis [Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, North Carolina (United States); Oleson, James R. [Department of Radiation Oncology, Duke University, Durham, North Carolina (United States); Division of Radiation Oncology, Veterans Administration Medical Center, Durham, North Carolina (United States); Lee, Walter T. [Department of Radiation Oncology, Duke University, Durham, North Carolina (United States); Division of Head and Neck Surgery and Communicative Sciences, Duke University Medical Center, Durham, North Carolina (United States); Section of Otolaryngology Head and Neck Surgery, Veterans Administration Medical Center, Durham, North Carolina (United States); Brizel, David M. [Department of Radiation Oncology, Duke University, Durham, North Carolina (United States); Division of Head and Neck Surgery and Communicative Sciences, Duke University Medical Center, Durham, North Carolina (United States); Ramanujam, Nimmi [Department of Biomedical Engineering, Duke University, Durham, North Carolina (United States); Dewhirst, Mark W., E-mail: mark.dewhirst@duke.edu [Department of Radiation Oncology, Duke University, Durham, North Carolina (United States)

2016-10-01

Purpose: To test whether oxygenation kinetics correlate with the likelihood for local tumor control after fractionated radiation therapy. Methods and Materials: We used diffuse reflectance spectroscopy to noninvasively measure tumor vascular oxygenation and total hemoglobin concentration associated with radiation therapy of 5 daily fractions (7.5, 9, or 13.5 Gy/d) in FaDu xenografts. Spectroscopy measurements were obtained immediately before each daily radiation fraction and during the week after radiation therapy. Oxygen saturation and total hemoglobin concentration were computed using an inverse Monte Carlo model. Results: First, oxygenation kinetics during and after radiation therapy, but before tumor volumes changed, were associated with local tumor control. Locally controlled tumors exhibited significantly faster increases in oxygenation after radiation therapy (days 12-15) compared with tumors that recurred locally. Second, within the group of tumors that recurred, faster increases in oxygenation during radiation therapy (day 3-5 interval) were correlated with earlier recurrence times. An area of 0.74 under the receiver operating characteristic curve was achieved when classifying the local control tumors from all irradiated tumors using the oxygen kinetics with a logistic regression model. Third, the rate of increase in oxygenation was radiation dose dependent. Radiation doses ≤9.5 Gy/d did not initiate an increase in oxygenation, whereas 13.5 Gy/d triggered significant increases in oxygenation during and after radiation therapy. Conclusions: Additional confirmation is required in other tumor models, but these results suggest that monitoring tumor oxygenation kinetics could aid in the prediction of local tumor control after radiation therapy.

Oxygen and Perfusion Kinetics in Response to Fractionated Radiation Therapy in FaDu Head and Neck Cancer Xenografts Are Related to Treatment Outcome

International Nuclear Information System (INIS)

Hu, Fangyao; Vishwanath, Karthik; Salama, Joseph K.; Erkanli, Alaattin; Peterson, Bercedis; Oleson, James R.; Lee, Walter T.; Brizel, David M.; Ramanujam, Nimmi; Dewhirst, Mark W.

2016-01-01

Purpose: To test whether oxygenation kinetics correlate with the likelihood for local tumor control after fractionated radiation therapy. Methods and Materials: We used diffuse reflectance spectroscopy to noninvasively measure tumor vascular oxygenation and total hemoglobin concentration associated with radiation therapy of 5 daily fractions (7.5, 9, or 13.5 Gy/d) in FaDu xenografts. Spectroscopy measurements were obtained immediately before each daily radiation fraction and during the week after radiation therapy. Oxygen saturation and total hemoglobin concentration were computed using an inverse Monte Carlo model. Results: First, oxygenation kinetics during and after radiation therapy, but before tumor volumes changed, were associated with local tumor control. Locally controlled tumors exhibited significantly faster increases in oxygenation after radiation therapy (days 12-15) compared with tumors that recurred locally. Second, within the group of tumors that recurred, faster increases in oxygenation during radiation therapy (day 3-5 interval) were correlated with earlier recurrence times. An area of 0.74 under the receiver operating characteristic curve was achieved when classifying the local control tumors from all irradiated tumors using the oxygen kinetics with a logistic regression model. Third, the rate of increase in oxygenation was radiation dose dependent. Radiation doses ≤9.5 Gy/d did not initiate an increase in oxygenation, whereas 13.5 Gy/d triggered significant increases in oxygenation during and after radiation therapy. Conclusions: Additional confirmation is required in other tumor models, but these results suggest that monitoring tumor oxygenation kinetics could aid in the prediction of local tumor control after radiation therapy.

Temperature-Corrected Oxygen Detection Based on Multi-Mode Diode Laser Correlation Spectroscopy

Directory of Open Access Journals (Sweden)

Xiutao Lou

2013-01-01

Full Text Available Temperature-corrected oxygen measurements were performed by using multi-mode diode laser correlation spectroscopy at temperatures ranging between 300 and 473 K. The experiments simulate in situ monitoring of oxygen in coal-combustion exhaust gases at the tail of the flue. A linear relationship with a correlation coefficient of −0.999 was found between the evaluated concentration and the gas temperature. Temperature effects were either auto-corrected by keeping the reference gas at the same conditions as the sample gas, or rectified by using a predetermined effective temperature-correction coefficient calibrated for a range of absorption wavelengths. Relative standard deviations of the temperature-corrected oxygen concentrations obtained by different schemes and at various temperatures were estimated, yielding a measurement precision of 0.6%.

Growth and chemosensory behavior of sulfate-reducing bacteria in oxygen-sulfide gradients

DEFF Research Database (Denmark)

Sass, Andrea M.; Wieland, Andrea Eschemann; Kühl, Michael

2002-01-01

Growth and chemotactic behavior in oxic–anoxic gradients were studied with two freshwater and four marine strains of sulfate-reducing bacteria related to the genera Desulfovibrio, Desulfomicrobium or Desulfobulbus. Cells were grown in oxygen–sulfide counter-gradients within tubes filled with agar...... chemotactically to lactate, nitrate, sulfate and thiosulfate, and even sulfide functioned as an attractant. In oxic–anoxic gradients the bacteria moved away from high oxygen concentrations and formed bands at the outer edge of the oxic zone at low oxygen concentration (... to actively change the extension and slope of the gradients by oxygen reduction with lactate or even sulfide as electron donor. Generally, the chemotactic behavior was in agreement with a defense strategy that re-establishes anoxic conditions, thus promoting anaerobic growth and, in a natural community...

Comparison between model-predicted tumor oxygenation dynamics and vascular-/flow-related Doppler indices.

Science.gov (United States)

Belfatto, Antonella; Vidal Urbinati, Ailyn M; Ciardo, Delia; Franchi, Dorella; Cattani, Federica; Lazzari, Roberta; Jereczek-Fossa, Barbara A; Orecchia, Roberto; Baroni, Guido; Cerveri, Pietro

2017-05-01

Mathematical modeling is a powerful and flexible method to investigate complex phenomena. It discloses the possibility of reproducing expensive as well as invasive experiments in a safe environment with limited costs. This makes it suitable to mimic tumor evolution and response to radiotherapy although the reliability of the results remains an issue. Complexity reduction is therefore a critical aspect in order to be able to compare model outcomes to clinical data. Among the factors affecting treatment efficacy, tumor oxygenation is known to play a key role in radiotherapy response. In this work, we aim at relating the oxygenation dynamics, predicted by a macroscale model trained on tumor volumetric data of uterine cervical cancer patients, to vascularization and blood flux indices assessed on Ultrasound Doppler images. We propose a macroscale model of tumor evolution based on three dynamics, namely active portion, necrotic portion, and oxygenation. The model parameters were assessed on the volume size of seven cervical cancer patients administered with 28 fractions of intensity modulated radiation therapy (IMRT) (1.8 Gy/fraction). For each patient, five Doppler ultrasound tests were acquired before, during, and after the treatment. The lesion was manually contoured by an expert physician using 4D View ® (General Electric Company - Fairfield, Connecticut, United States), which automatically provided the overall tumor volume size along with three vascularization and/or blood flow indices. Volume data only were fed to the model for training purpose, while the predicted oxygenation was compared a posteriori to the measured Doppler indices. The model was able to fit the tumor volume evolution within 8% error (range: 3-8%). A strong correlation between the intrapatient longitudinal indices from Doppler measurements and oxygen predicted by the model (about 90% or above) was found in three cases. Two patients showed an average correlation value (50-70%) and the remaining

On-line determination of glucose and lactate concentrations in animal cell culture based on fibre optic detection of oxygen in flow-injection analysis.

Science.gov (United States)

Dremel, B A; Li, S Y; Schmid, R D

1992-01-01

A flow-injection analysis (FIA) system based on fibre optic detection of oxygen consumption using immobilized glucose oxidase (GOD) and lactate oxidase (LOD) is described for the on-line monitoring of glucose and lactate concentrations in animal cell cultures. The consumption of oxygen was determined via dynamic quenching by molecular oxygen of the fluorescence of an indicator. GOD and LOD were immobilized on controlled pore glass (CPG) in enzyme reactors which were directly linked to a specially designed fibre optic flow-through cell covering the oxygen optrode. The system is linear for 0-30 mM glucose, with an r.s.d. of 5% at 30 mM (five measurements) and for 0-30 mM lactate, with an r.s.d. of 5% at 30 mM (five measurements). The enzyme reactors used were stable for more than 4 weeks in continuous operation, and it was possible to analyse up to 20 samples per hour. The system has been successfully applied to the on-line monitoring of glucose and lactate concentrations of an animal cell culture designed for the production of recombinant human antithrombine III (AT-III). Results of the on-line measurement obtained by the FIA system were compared with the off-line results obtained by a glucose and lactate analyser from Yellow Springs Instrument Company (YSI).

An atomistic vision of the Mass Action Law: Prediction of carbon/oxygen defects in silicon

Energy Technology Data Exchange (ETDEWEB)

Brenet, G.; Timerkaeva, D.; Caliste, D.; Pochet, P. [CEA, INAC-SP2M, Atomistic Simulation Laboratory, F-38000 Grenoble (France); Univ. Grenoble Alpes, INAC-SP2M, L-Sim, F-38000 Grenoble (France); Sgourou, E. N.; Londos, C. A. [University of Athens, Solid State Physics Section, Panepistimiopolis Zografos, Athens 157 84 (Greece)

2015-09-28

We introduce an atomistic description of the kinetic Mass Action Law to predict concentrations of defects and complexes. We demonstrate in this paper that this approach accurately predicts carbon/oxygen related defect concentrations in silicon upon annealing. The model requires binding and migration energies of the impurities and complexes, here obtained from density functional theory (DFT) calculations. Vacancy-oxygen complex kinetics are studied as a model system during both isochronal and isothermal annealing. Results are in good agreement with experimental data, confirming the success of the methodology. More importantly, it gives access to the sequence of chain reactions by which oxygen and carbon related complexes are created in silicon. Beside the case of silicon, the understanding of such intricate reactions is a key to develop point defect engineering strategies to control defects and thus semiconductors properties.

Kinetics of oxygen exchange between bisulfite ion and water as studied by oxygen-17 nuclear magnetic resonance spectroscopy

International Nuclear Information System (INIS)

Horner, D.A.

1984-08-01

The nuclear magnetic relaxation times of oxygen-17 have been measured in aqueous sodium bisulfite solutions in the pH range from 2.5 to 5 as a function of temperature, pH, and S(IV) concentration, at an ionic strength of 1.0 m. The rate law for oxygen exchange between bisulfite ion and water was obtained from an analysis of the data, and is consistent with oxygen exchange occurring via the reaction SO 2 + H 2 O right reversible H + + SHO 3 - . The value of k/sub -1/ is in agreement with relaxation measurements. Direct spectroscopic evidence was found for the existence of two isomers of bisulfite ion: one with the proton bonded to the sulfur (HSO 3 - ) and the other with the proton bonded to an oxygen (SO 3 H - ). (The symbol SHO 3 - in the above chemical equation refers to both isomeric forms of bisulfite ion.) The relative amounts of the two isomers were determined as a function of temperature, and the rate and mechanism of oxygen exchange between the two was investigated. One of the two isomers, presumably SO 3 H - , exchanges oxygens with water much more rapidly than does the other. A two-pulse sequence was developed which greatly diminished the solvent peak in the NMR spectrum

Oxygenation decreases elastin secretion from rat ductus arteriosus smooth muscle cells.

Science.gov (United States)

Kawakami, Shoji; Minamisawa, Susumu

2015-08-01

The ductus arteriosus (DA), a fetal arterial connection between the main pulmonary artery and the descending aorta, normally closes immediately after birth. The oxygen concentration in the blood rises after birth, and in the DA this increase in oxygen concentration causes functional closure, which is induced by smooth muscle contraction. Previous studies have demonstrated that hypoxia and/or oxygenation affect vascular remodeling of various vessels. Therefore, we hypothesized that the rise in oxygen concentration would affect the vascular structure of the DA due to production of proteins secreted from DA smooth muscle cells (SMC). Liquid chromatography-tandem mass spectrometry was used to comprehensively investigate the secreted proteins in the supernatant of rat DA SMC harvested under hypoxic conditions (1% oxygen) or under normoxic conditions (21% oxygen). We found that the rise in oxygen concentration reduced the secretion of elastin from DA SMC. On reverse transcription-polymerase chain reaction, the expression of elastin mRNA was not significantly changed in DA SMC from hypoxic to normoxic conditions. Given that elastin forms internal elastic lamina and elastic fibers in the vascular muscle layers, and that a rise in oxygen concentration reduced the secretion of elastin, this suggests that the rise in blood oxygen concentration after birth reduces the secretion of elastin, and therefore may play a role in DA structural remodeling after birth. © 2015 Japan Pediatric Society.

Investigation of the singlet delta oxygen and ozone yields from the pulsed radiolysis of oxygen and oxygen-noble gas mixtures

International Nuclear Information System (INIS)

Zediker, M.S.

1984-01-01

The experiments discussed herein were performed with a flowing gas apparatus coupled to the University of Illinois TRIGA reactor. The detectors (lambda = 1.27 μ 634 nm) were calibrated with a novel NO 2 titration scheme and the absorbed dose was estimated from the ozone concentrations measured in pure oxygen. The results of these experiments revealed an O 2 (a 1 Δ) production efficiency of 0.14% for direct nuclear pumping in an argon-oxygen mixture. Extensive modeling of the oxygen and argon-oxygen mixtures were benchmarked against these and other experiments. However, good agreement over a broad absorbed dose range was only possible if the O 4 + + O 4 - neutralization reaction was assumed to be nondissociative. In a second set of experiments with a nuclear sustained electrical discharge (low E/N), the O 2 (a 1 Δ) production efficiency was approx.0.40% for the electrical power densities examined. In addition, the O 2 (a 1 Δ) was observed to scale with the square root of the electrical power deposition but was independent of the oxygen concentration. A simple analytic model was developed which explains this behavior as a characteristic of an externally sustained discharge involving an electron attaching gas such as oxygen. The results of these experiments and the modeling of the chemical kinetics are discussed with an emphasis on optimizing the O 2 (a 1 Δ) and O 3 yields

Formation and Migration of Oxygen Vacancies in SrCoO3 and their effect on Oxygen Evolution Reactions

KAUST Repository

Tahini, Hassan A.; Tan, Xin; Schwingenschlö gl, Udo; Smith, Sean C.

2016-01-01

Perovskite SrCoO3 is a potentially useful material for promoting the electrocatalytic oxygen evolution reaction, with high activities predicted theoretically and observed experimentally for closely related doped perovskite materials. However, complete stoichiometric oxidation is very difficult to realize experimentally – in almost all cases there are significant fractions of oxygen vacancies present. Here, using first principles calculations we study oxygen vacancies in perovskite SrCoO3 from thermodynamic, electronic and kinetic points of view. We find that an oxygen vacancy donates two electrons to neighboring Co sites in the form of localized charge. The formation energy of a single vacancy is very low and estimated to be 1.26 eV in the dilute limit. We find that a vacancy is quite mobile with a migration energy of ~0.5 eV. Moreover, we predict that oxygen vacancies exhibit a tendency towards clustering which is in accordance with the material’s ability to form a variety of oxygen-deficient structures. These vacancies have a profound effect on the material’s ability to facilitate OER, increasing the overpotential from ~0.3 V for the perfect material to ~0.7 for defective surfaces. A moderate compressive biaxial strain (2%) is predicted here to increase the surface oxygen vacancy formation energy by ca. 30%, thus reducing the concentration of surface vacancies and thereby preserving the OER activity of the material.

Formation and Migration of Oxygen Vacancies in SrCoO3 and their effect on Oxygen Evolution Reactions

KAUST Repository

Tahini, Hassan A.

2016-07-18

Perovskite SrCoO3 is a potentially useful material for promoting the electrocatalytic oxygen evolution reaction, with high activities predicted theoretically and observed experimentally for closely related doped perovskite materials. However, complete stoichiometric oxidation is very difficult to realize experimentally – in almost all cases there are significant fractions of oxygen vacancies present. Here, using first principles calculations we study oxygen vacancies in perovskite SrCoO3 from thermodynamic, electronic and kinetic points of view. We find that an oxygen vacancy donates two electrons to neighboring Co sites in the form of localized charge. The formation energy of a single vacancy is very low and estimated to be 1.26 eV in the dilute limit. We find that a vacancy is quite mobile with a migration energy of ~0.5 eV. Moreover, we predict that oxygen vacancies exhibit a tendency towards clustering which is in accordance with the material’s ability to form a variety of oxygen-deficient structures. These vacancies have a profound effect on the material’s ability to facilitate OER, increasing the overpotential from ~0.3 V for the perfect material to ~0.7 for defective surfaces. A moderate compressive biaxial strain (2%) is predicted here to increase the surface oxygen vacancy formation energy by ca. 30%, thus reducing the concentration of surface vacancies and thereby preserving the OER activity of the material.

Oxygen negative glow: reactive species and emissivity

International Nuclear Information System (INIS)

Sahli, Khaled

1991-01-01

This research thesis addresses the study of a specific type of oxygen plasma created by electron beams (1 keV, 20 mA/cm"2), negative glow of a luminescent discharge in abnormal regime. The objective is to test the qualities of this plasma as source of two 'active' species of oxygen (singlet molecular oxygen and atomic oxygen) which are useful in applications. The experiment mainly bears on the use of VUV (120 to 150 nm) absorption spectroscopy measurements of concentrations of these both species, and on the recording of plasma emissivity space profiles in the visible region (450 to 850 nm). It appears that low concentrations of singlet oxygen definitely exclude this type of discharge for iodine laser applications. On the contrary, concentrations measured for atomic oxygen show it is a good candidate for the oxidation of large surfaces by sheets of beams. The satisfying comparison of emissivity results with a published model confirm the prevailing role of fast electrons, and gives evidence of an important effect of temperature: temperature can reach 1000 K, and this is in agreement with the presented measurement [fr

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

National Research Council Canada - National Science Library

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...

Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

Science.gov (United States)

Gurley, Katelyn; Shang, Yu; Yu, Guoqiang

2012-07-01

This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (\\Vdot O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and \\Vdot O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (r\\Vdot O2). The rBF and r\\Vdot O2 signals were calibrated with absolute baseline BF and \\Vdot O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology.

Direct measurement of local oxygen concentration in the bone marrow of live animals

Science.gov (United States)

Spencer, Joel A.; Ferraro, Francesca; Roussakis, Emmanuel; Klein, Alyssa; Wu, Juwell; Runnels, Judith M.; Zaher, Walid; Mortensen, Luke J.; Alt, Clemens; Turcotte, Raphaël; Yusuf, Rushdia; Côté, Daniel; Vinogradov, Sergei A.; Scadden, David T.; Lin, Charles P.

2014-04-01

Characterization of how the microenvironment, or niche, regulates stem cell activity is central to understanding stem cell biology and to developing strategies for the therapeutic manipulation of stem cells. Low oxygen tension (hypoxia) is commonly thought to be a shared niche characteristic in maintaining quiescence in multiple stem cell types. However, support for the existence of a hypoxic niche has largely come from indirect evidence such as proteomic analysis, expression of hypoxia inducible factor-1α (Hif-1α) and related genes, and staining with surrogate hypoxic markers (for example, pimonidazole). Here we perform direct in vivo measurements of local oxygen tension (pO2) in the bone marrow of live mice. Using two-photon phosphorescence lifetime microscopy, we determined the absolute pO2 of the bone marrow to be quite low (hypoxic as it is perfused with small arteries that are often positive for the marker nestin. These pO2 values change markedly after radiation and chemotherapy, pointing to the role of stress in altering the stem cell metabolic microenvironment.

Oxygen optodes as fast sensors for eddy correlation measurements in aquatic systems

DEFF Research Database (Denmark)

Chipman, Lindsay; Huettel, Markus; Berg, Peter

2012-01-01

The aquatic eddy-correlation technique can be used to noninvasively determine the oxygen exchange across the sediment-water interface by analyzing the covariance of vertical flow velocity and oxygen concentration in a small measuring volume above the sea bed. The method requires fast sensors...... that combine the advantages of noninvasive measurements and integration of fluxes over a large footprint area, using a relatively rugged and less expensive sensor....

Crosstalk between nitrite, myoglobin and reactive oxygen species to regulate vasodilation under hypoxia.

Directory of Open Access Journals (Sweden)

Matthias Totzeck

Full Text Available The systemic response to decreasing oxygen levels is hypoxic vasodilation. While this mechanism has been known for more than a century, the underlying cellular events have remained incompletely understood. Nitrite signaling is critically involved in vessel relaxation under hypoxia. This can be attributed to the presence of myoglobin in the vessel wall together with other potential nitrite reductases, which generate nitric oxide, one of the most potent vasodilatory signaling molecules. Questions remain relating to the precise concentration of nitrite and the exact dose-response relations between nitrite and myoglobin under hypoxia. It is furthermore unclear whether regulatory mechanisms exist which balance this interaction. Nitrite tissue levels were similar across all species investigated. We then investigated the exact fractional myoglobin desaturation in an ex vivo approach when gassing with 1% oxygen. Within a short time frame myoglobin desaturated to 58±12%. Given that myoglobin significantly contributes to nitrite reduction under hypoxia, dose-response experiments using physiological to pharmacological nitrite concentrations were conducted. Along all concentrations, abrogation of myoglobin in mice impaired vasodilation. As reactive oxygen species may counteract the vasodilatory response, we used superoxide dismutase and its mimic tempol as well as catalase and ebselen to reduce the levels of reactive oxygen species during hypoxic vasodilation. Incubation of tempol in conjunction with catalase alone and catalase/ebselen increased the vasodilatory response to nitrite. Our study shows that modest hypoxia leads to a significant nitrite-dependent vessel relaxation. This requires the presence of vascular myoglobin for both physiological and pharmacological nitrite levels. Reactive oxygen species, in turn, modulate this vasodilation response.

A Low-Power Medical Oxygen Generator, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — An on-board oxygen concentrator is required during long duration manned space missions to supply medical oxygen. The commercial medical oxygen generators based on...

A Low-Power Medical Oxygen Generator, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — An on-board oxygen concentrator is required during long duration manned space missions to supply medical oxygen. The commercial medical oxygen generators based on...

A laser-based sensor for measurement of off-gas composition and temperature in basic oxygen steelmaking

International Nuclear Information System (INIS)

Ottesen, D.; Allendorf, S.; Ludowise, P.; Hardesty, D.; Miller, T.; Goldstein, D.; Smith, C.; Bonin, M.

1999-01-01

We are developing an optical sensor for process control in basic oxygen steelmaking. The sensor measures gas temperature and relative CO/CO 2 concentration ratios in the furnace off-gas by transmitting the laser probe beam directly above the furnace lip and below the exhaust hood during oxygen blowing. Dynamic off-gas information is being evaluated for optimizing variables such as lance height, oxygen flow, post-combustion control, and prediction of final melt-carbon content. The non-invasive nature of the optical sensor renders it robust and relatively maintenance-free. Additional potential applications of the method are process control for electric arc furnace and bottom-blown oxygen steelmaking processes. (author)

Efficient simultaneous partial nitrification, anammox and denitrification (SNAD) system equipped with a real-time dissolved oxygen (DO) intelligent control system and microbial community shifts of different substrate concentrations.

Science.gov (United States)

Wen, Xin; Gong, Benzhou; Zhou, Jian; He, Qiang; Qing, Xiaoxia

2017-08-01

Simultaneous partial nitrification, anammox and denitrification (SNAD) process was studied in a sequencing batch biofilm reactor (SBBR) fed with synthetic wastewater in a range of 2200 mgN/L ∼ 50 mgN/L. Important was an external real-time precision dissolved oxygen (DO) intelligent control system that consisted of feed forward control system and feedback control system. This DO control system permitted close control of oxygen supply according to influent concentration, effluent quality and other environmental factors in the reactor. In this study the operation was divided into six phases according to influent nitrogen applied. SNAD system was successfully set up after adding COD into a CANON system. And the presence of COD enabled the survival of denitrifiers, and made Thauera and Pseudomonas predominant as functional denitrifiers in this system. Denaturing gradient gel electrophoresis (DGGE), fluorescence in situ hybridization (FISH) and 16S rRNA amplicon pyrosequencing were used to analyze the microbial variations of different substrate concentrations. Results indicated that the relative population of ammonia oxidizing bacteria (AOB) members decreased when influent ammonia concentration decreased from 2200 mg/L to 50 mg/L, while no dramatic drop of the percent of anammox bacteria was seen. And Nitrosomonas europaea was the predominant AOB in SNAD system treating sewage, while Candidatus Brocadia was the dominant anammox bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

Single-dose relative biological effectiveness and toxicity studies under conditions of hypothermia and hyperbaric oxygen

International Nuclear Information System (INIS)

Hering, E.R.; Blekkenhorst, G.; Harrison, G.G.; Morrell, D.; Korrubel, J.; Gregory, A.; Phillips, J.; Manca, V.; Sealy, R.; Cape Town Univ.

1986-01-01

An approach to using hyperbaric oxygen with radiation in a clinical situation has been described in the preceding paper in this issue. To ascertain whether there might be a change in the relative biological effectiveness of radiation on normal mammalian tissue treated under conditions of hypothermia and hyperbaric oxygen, the acute reaction to radiation of pig skin was studied. A single dose enhancement ratio at the erythema reaction level of 1.4+-0.08 was obtained when compared with irradiation at normal body temperature in air. The authors studied also a series of antioxidant enzymes in rat liver and lung after exposure to hypothermia and hyperbaric oxygen. Enzyme changes were such as to combat oxygen toxicity which might develop as a result of the pre-treatment. (author)

Oxygen consumption by hydrazine in long sample lines

International Nuclear Information System (INIS)

Chi, Lisheng; Turner, Carl-W.

2012-09-01

In nuclear power plants secondary side system dissolved oxygen concentration is a strictly controlled chemistry parameter intended to minimize corrosion and fouling of steam cycle components. Low dissolved oxygen concentration is maintained by a combination of mechanical de-aeration and chemical reaction. The dissolved oxygen concentration in feedwater is monitored by sampling systems to ensure it remains within station specification during operation. The sample lines in a nuclear power plant's sampling system can be from 5 to nearly 200 meters in length, resulting in sample residence times between the take-off point to the analyzer from a few seconds to several minutes, depending on the flow rate and the length of the sample line. For many chemical parameters the residence time is of no concern. For measurements of dissolved oxygen and hydrazine in the secondary coolant, however, for residence times longer than one minute, it is uncertain whether the sample is representative of conditions in the secondary coolant, especially for samples taken from locations where the temperature is well over 100 deg. C. To address this concern, a series of tests were conducted under both warm-up and power operation conditions, respectively, to investigate the effect of temperature, residence time, sample line length, surface area, hydrazine-to-oxygen ratio, and the concentrations of dissolved oxygen and hydrazine on the consumption of oxygen by hydrazine. The test results revealed that dissolved oxygen measurements in CANDU plants are underestimated to various degrees, depending on the sampling system operating conditions. Two distinct types of behaviours are observed for the oxygen removal rate: 1) the percentage removal of dissolved oxygen is invariant with time during the tests, and increases with increasing residence time in the test section, when the reaction between hydrazine and oxygen is better described by a homogenous reaction mechanism, and 2) the percentage oxygen

Evaluation of Oxygen Concentrators and Chemical Oxygen Generators at Altitude and Temperature Extremes

Science.gov (United States)

2015-04-22

Current COGs typically contain one or more of the following solid compounds: sodium chlorate , sodium perchlorate, potassium superoxide, or...produces heat. The COGs evaluated in this study are the O2PAK, TraumAid, and BOB. 3.2.1 O2PAK. The main ingredient in the O2PAK is sodium chlorate ...In 1902, the Lancet reported on Kamm’s oxygen generator invention for medical use. The device used chlorate cakes and manganese oxide and, when

Interactions between oxygen permeation and homogeneous-phase fuel conversion on the sweep side of an ion transport membrane

KAUST Repository

Hong, Jongsup

2013-02-01

The interactions between oxygen permeation and homogeneous fuel oxidation reactions on the sweep side of an ion transport membrane (ITM) are examined using a comprehensive model, which couples the dependency of the oxygen permeation rate on the membrane surface conditions and detailed chemistry and transport in the vicinity of the membrane. We assume that the membrane surface is not catalytic to hydrocarbon or syngas oxidation. Results show that increasing the sweep gas inlet temperature and fuel concentration enhances oxygen permeation substantially. This is accomplished through promoting oxidation reactions (oxygen consumption) and the transport of the products and reaction heat towards the membrane, which lowers the oxygen concentration and increases the gas temperature near the membrane. Faster reactions at higher fuel concentration and higher inlet gas temperature support substantial fuel conversion and lead to a higher oxygen permeation flux without the contribution of surface catalytic activity. Beyond a certain maximum in the fuel concentration, extensive heat loss to the membrane (and feed side) reduces the oxidation kinetic rates and limits oxygen permeation as the reaction front reaches the membrane. The sweep gas flow rate and channel height have moderate impacts on oxygen permeation and fuel conversion due to the residence time requirements for the chemical reactions and the location of the reaction zone relative to the membrane surface. © 2012 Elsevier B.V.

Variations of dissolved oxygen in Mandovi and Zuari estuaries

Digital Repository Service at National Institute of Oceanography (India)

DeSousa, S.N.; SenGupta, R.

During non-monsoon months the estuaries were well mixed showing uniform oxygen concentrations from surface to bottom. However, during monsoon months both the estuaries showed stratified conditions with surface water showing high oxygen concentration...

Oxygen enriched air using membrane for palm oil wastewater treatment

Directory of Open Access Journals (Sweden)

Ramlah Mohd Tajuddin

2002-11-01

Full Text Available A research aimed to explore new method of aeration using oxygen enriched air performance on BOD reduction of palm oil wastewater was conducted. The oxygen enriched air was obtained from an Oxygen Enriched System (OES developed using asymmetric polysulfone hollow fiber membrane with composition consisting of PSF: 22%, DMAc: 31.8%, THF: 31.8%, EtOH: 14.4%. Palm oil wastewater samples were taken from facultative pond effluent. These samples were tested for its initial biochemical oxygen demand (BOD, total suspended solids (TSS, pH, conductivity, turbidity, dissolved oxygen (DO, suspended solids (SS, and total dissolved solids (TDS before being subjected to two modes of aeration system, that is diffused air and oxygen enriched air. These water quality concentrations were tested for every 20 minutes for two-hour period during the aeration process. Results of BOD, TSS, pH, conductivity, DO, SS and TDS concentrations against time of samples from the two modes of aeration were then compared. It was found that DO concentration achieved in oxygen enriched air aeration was better than aeration using diffused air system. Aeration using OES improve the DO concentration in the wastewater and thus improve the BOD reduction and also influence other physical characteristics of wastewater. This phenomenon indicates the advantage of using air with higher oxygen concentration for wastewater aeration instead of diffused air system.

Inhaled nitric oxide and high concentrations of oxygen in pediatrics patients with congenital cardiopathy and pulmonary hypertension: report of five cases

Directory of Open Access Journals (Sweden)

Werther Brunow de Carvalho

Full Text Available Five patients with ages ranging from 6 months to 3 years were analyzed. All received inhaled nitric oxide (NO - 20 parts per million (ppm and oxygen (0(2 - at a concentration of 90-95% by means of an oxygen hood. Mean Pulmonary Artery Pressure (MPAP, Mean Aortic Pressure (MAoP, Pulmonary Vascular Resistance (PVR and Systemic Vascular Resistance (SVR were measured and the calculation of their relationship to pulmonary/systemic flow (Qp/Qs was performed by the catheterization' of the femoral artery vein. Three patients presented reduction in PVR and increase in Qp/Qs. There were no systemic alterations or any side effect from using NO.

Photoplethysmography for blood volumes and oxygenation changes during intermittent vascular occlusions.

Science.gov (United States)

Abay, T Y; Kyriacou, P A

2018-06-01

Photoplethysmography (PPG) is an optical technique that measures blood volume variations. The main application of dual-wavelength PPG is pulse oximetry, in which the arterial oxygen saturation (SpO[Formula: see text]) is calculated noninvasively. However, the PPG waveform contains other significant physiological information that can be used in conjunction to SpO[Formula: see text] for the assessment of oxygenation and blood volumes changes. This paper investigates the use of near infrared spectroscopy (NIRS) processing techniques for extracting relative concentration changes of oxygenated ([Formula: see text]HbO[Formula: see text]), reduced ([Formula: see text]HHb) and total haemoglobin ([Formula: see text]tHb) from dual-wavelength PPG signals during intermittent pressure-increasing vascular occlusions. A reflectance PPG sensor was attached on the left forearm of nineteen (n = 19) volunteers, along with a reference NIRS sensor positioned on the same forearm, above the left brachioradialis. The investigation protocol consisted of seven intermittent and pressure-increasing vascular occlusions. Relative changes in haemoglobin concentrations were obtained by applying the modified Beer-Lambert law to PPG signals, while oxygenation changes were estimated by the difference between red and infrared attenuations of DC PPGs (A[Formula: see text] = [Formula: see text]A[Formula: see text] - [Formula: see text]A[Formula: see text]) and by the conventional SpO[Formula: see text]. The [Formula: see text]HbO[Formula: see text], [Formula: see text]HHb, [Formula: see text]tHb from the PPG signals indicated significant changes in perfusion induced by either partial and complete occlusions (p < 0.05). The trends in the variables extracted from PPG showed good correlation with the same parameters measured by the reference NIRS monitor. Bland and Altman analysis of agreement between PPG and NIRS showed underestimation of the magnitude of changes by the PPG. A[Formula: see text

O mínimo de oxigênio na costa leste do Brasil entre 7-22ºS The minimum oxygen concentration in easthern Brasilian coast between 7-22ºS

Directory of Open Access Journals (Sweden)

Argeo Magliocca

1978-01-01

Full Text Available In the South Atlantic nearly the Brazilian coast, at low latitudes, the layer of minimum oxygen concentration shows distinct values between the Equatorial region (7ºS and the region limited by latitudes of 18-22ºS. In the vicinity of the Equator the minimum concentration is remarkably clear (2,0 ml/l at 7ºS and at 22ºS the minima values raise up to 4.0-4.5 ml/l. The minimum oxygen layer follows the isopynics surfaces (σt = 26.8-27.2 in depths of 300-400 m (7ºS and 600-800 m (22ºS . The oxygen concentration in this area results from a biochemical and physical processes, due to the presence of poor water Brazil Current southward and the rich one Intermediate Antartic water flowing northward.

Blood oxygen and carbon dioxide transport in man

OpenAIRE

McElderry, Linda A.

1981-01-01

The effect of long term domiciliary oxygen therapy on the position and shape of the oxygen dissociation curve, together with other haematologic variables such as 2,3- diphosphoglycerate (2,3-DPG), haemoglobin concentration, packed cell volume, mean corpuscular haemoglobin concentration, and arterial blood gas and pH values, has been studied in patients with chronic bronchitis. Twenty-six patients were randomly allocated to receive either no oxygen therapy or 15 hours p...

Expression of T helper cell-associated inflammatory mediator mRNAs in cells of bronchoalveolar lavage fluid samples and oxygen concentration in arterial blood samples from healthy horses exposed to hyperbaric oxygen.

Science.gov (United States)

Looijen, Maty G P; New, Dallas J; Fischer, Carrie D; Dardari, Rkia; Irwin, Karyn M; Berezowski, Christopher J; Bond, Stephanie L; Léguillette, Renaud

2016-10-01

OBJECTIVE To evaluate the mRNA expression of T helper (Th)1, Th2, and Th17 cell-associated inflammatory mediators in cells of bronchoalveolar lavage fluid samples collected from healthy horses exposed to hyperbaric oxygen (HBO) and to monitor blood oxygen concentration during and following HBO therapy. ANIMALS 8 healthy horses. PROCEDURES In a randomized controlled crossover design study, each horse was exposed (beginning day 1) to 100% oxygen at a maximum of 3 atmospheres absolute (304 kPa) daily for 10 days or ambient air at atmospheric pressure in the HBO chamber for an equivalent amount of time (control). Bronchoalveolar lavage fluid samples were collected on days 0 and 10. After validation of candidate reference genes, relative mRNA expressions of various innate inflammatory, Th1 cell-derived, Th2 cell-derived (including eotaxin-2), Th17 cell-derived, and regulatory cytokines were measured by quantitative PCR assays. For 3 horses, arterial blood samples were collected for blood gas analysis during a separate HBO session. RESULTS The optimal combination of reference genes was glyceraldehyde-3-phosphate dehydrogenase, hypoxanthine ribosyltransferase, and ribosomal protein L32. Compared with day 0 findings, expression of eotaxin-2 mRNA was significantly lower (0.12-fold reduction) and the percentage of neutrophils in bronchoalveolar lavage fluid samples was significantly lower on day 10 when horses received HBO therapy. Values of Pao2 rapidly increased (> 800 mm Hg) but immediately decreased to pretreatment values when HBO sessions ended. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that HBO therapy does not increase mRNA expression of inflammatory cytokines, but reduces eotaxin-2 mRNA transcription. The Pao2 increase was transient with no cumulative effects of HBO.

Oxygen sensitization of mammalian cells under different irradiation conditions

International Nuclear Information System (INIS)

Ling, C.C.; Michaels, H.B.; Gerweck, L.E.; Epp, E.R.; Peterson, E.C.

1981-01-01

The oxygen dependence of the radiosensitivity of cultured CHO cells was examined in detail with particular attention paid to avoiding possible artifacts due to radiolytic oxygen depletion. Two methods of gas equilibration and irradiation were used. In the first approach, cells were irradiated with 50-kVp X rays in a thin-layer geometry which offered maximum interchange between the cells and the surrounding gas. The second technique employed 280-kVp X irradiation of cells under full-medium conditions with mechanical agitation to minimize the effect of radiochemical oxygen consumption by promoting rapid oxygen replenishment. With these techniques oxygen radiosensitization was clearly resolved at an oxygen concentration of 0.03% in the gas phase. The oxygen K curves measured by these two methods were similar in shape over a wide range of oxygen concentration

The Upside-Down Biosphere: Evidence for the Partially Oxygenated Oceans During the Archean Eon

Science.gov (United States)

Domagal-Goldman, Shawn

2014-01-01

This is a commentary on the preceding chapter by Ohmoto et al., in which it is suggested that oxygen concentrations have been high throughout Earth history. This is a contentious suggestion at odds with the prevailing view in the field, which contends that atmospheric oxygen concentrations rose from trace levels to a few percent of modern-day levels around 2.5 b.y. ago. This comment notes that many of the data sets cited by Ohmoto et al. as evidence for a relatively oxidized environment come from deep-ocean settings. This presents a possibility to reconcile some of these data and suggestions with the overwhelming evidence for an atmosphere free of oxygen at that time. Specifically, it is possible that deep-ocean waters were relatively oxidized with respect to certain redox pairs. These deep-ocean waters would have been more oxidized than surface waters, thus representing an "upside-down biosphere," as originally proposed 25 years ago by Jim Walker.

Kinetics of oxygen species in an electrically driven singlet oxygen generator

Science.gov (United States)

Azyazov, V. N.; Torbin, A. P.; Pershin, A. A.; Mikheyev, P. A.; Heaven, M. C.

2015-12-01

The kinetics of oxygen species in the gaseous medium of a discharge singlet oxygen generator has been revisited. Vibrationally excited ozone O3(υ) formed in O + O2 recombination is thought to be a significant agent in the deactivation of singlet oxygen O2(a1Δ), oxygen atom removal and ozone formation. It is shown that the process O3(υ ⩾ 2) + O2(a1Δ) → 2O2 + O is the main O2(a1Δ) deactivation channel in the post-discharge zone. If no measures are taken to decrease the oxygen atom concentration, the contribution of this process to the overall O2(a1Δ) removal is significant, even in the discharge zone. A simplified model for the kinetics of vibrationally excited ozone is proposed. Calculations based on this model yield results that are in good agreement with the experimental data.

Real time continuous oxygen concentration monitoring system during malaxation for the production of Virgin Olive Oil

Directory of Open Access Journals (Sweden)

Aiello, G.

2012-10-01

Full Text Available During the mechanical extraction process of Virgin Olive Oil (VOO some important physical phenomena and enzymatic transformations occur which influence the quality of the final product. The control of process parameters is crucial to ensure the quality of VOO, therefore process monitoring and control is a fundamental requirement in the modern VOO processing industry. The present work proposes an innovative Real-Time Monitoring System (RTMS aimed at continuously measuring the oxygen concentration during the malaxation process in order to establish a correlation with the quality of the final product obtained. This monitoring system is based on an oxygen concentration sensor directly connected to the malaxation chamber and a data acquisition system to analyze and store the measured values in a process database. The experimental results obtained show that the use of oxygen during malaxation improves some qualitative parameters of VOO such as free fatty acids and total polyphenols while others (peroxide values and spectrophotometric indexes worsen. These results are similar to those obtained by employing nitrogen, which is the traditional technique to avoid the wellknown oxidation processes studied by several researchers, thus demonstrating that the presence of oxygen during the malaxation process can have beneficial effects on the quality of VOO when its concentration is properly controlled.

Durante el proceso de extracción mecánica del aceite de oliva virgen ocurren importantes fenómenos físicos y transformaciones enzimáticas que influyen en la calidad del producto final. El control de los parámetros del proceso es crucial para garantizar la calidad del aceite de oliva virgen, por tanto la monitorización y el control del proceso son requisitos fundamentales en el moderno tratamiento industrial del aceite de oliva virgen. El presente trabajo propone un sistema de monitorización innovador en tiempo real dirigido a medir continuamente

Time required for partial pressure of arterial oxygen equilibration during mechanical ventilation after a step change in fractional inspired oxygen concentration.

Science.gov (United States)

Cakar, N; Tuŏrul, M; Demirarslan, A; Nahum, A; Adams, A; Akýncý, O; Esen, F; Telci, L

2001-04-01

To determine the time required for the partial pressure of arterial oxygen (PaO2) to reach equilibrium after a 0.20 increment or decrement in fractional inspired oxygen concentration (FIO2) during mechanical ventilation. A multi-disciplinary ICU in a university hospital. Twenty-five adult, non-COPD patients with stable blood gas values (PaO2/FIO2 > or = 180 on the day of the study) on pressure-controlled ventilation (PCV). Following a baseline PaO2 (PaO2b) measurement at FIO2 = 0.35, the FIO2 was increased to 0.55 for 30 min and then decreased to 0.35 without any other change in ventilatory parameters. Sequential blood gas measurements were performed at 3, 5, 7, 9, 11, 15, 20, 25 and 30 min in both periods. The PaO2 values measured at the 30th min after a step change in FIO2 (FIO2 = 0.55, PaO2[55] and FIO2 = 0.35, PaO2[35]) were accepted as representative of the equilibrium values for PaO2. Each patient's rise and fall in PaO2 over time, PaO2(t), were fitted to the following respective exponential equations: PaO2b + (PaO2[55]-PaO2b)(1-e-kt) and PaO2[55] + (PaO2[35]-PaO2[55])(e-kt) where "t" refers to time, PaO2[55] and PaO2[35] are the final PaO2 values obtained at a new FIO2 of 0.55 and 0.35, after a 0.20 increment and decrement in FIO2, respectively. Time constant "k" was determined by a non-linear fitting curve and 90% oxygenation times were defined as the time required to reach 90% of the final equilibrated PaO2 calculated by using the non-linear fitting curves. Time constant values for the rise and fall periods were 1.01 +/- 0.71 min-1, 0.69 +/- 0.42 min-1, respectively, and 90% oxygenation times for rises and falls in PaO2 periods were 4.2 +/- 4.1 min-1 and 5.5 +/- 4.8 min-1, respectively. There was no significant difference between the rise and fall periods for the two parameters (p > 0.05). We conclude that in stable patients ventilated with PCV, after a step change in FIO2 of 0.20, 5-10 min will be adequate for obtaining a blood gas sample to measure a Pa

Major, Trace Element Concentration and Triple-Oxygen Isotope Compositions of G- and I-Type Spherules from the Sør Rondane Mountains, East Antarctica

Science.gov (United States)

Soens, B.; Goderis, S.; Greenwood, R. C.; McKibbin, S.; Van Ginneken, M.; Vanhaecke, F.; Debaille, V.; Franchi, I. A.; Claeys, Ph.

2017-07-01

We present new major, trace element concentration (LA-ICP-MS) and triple-oxygen isotope (LF-IRMS) data for G- and I-type cosmic spherules. This study suggests that both types of micrometeorites may originate from ordinary chondrite parent bodies.

Oxygen transport membrane

DEFF Research Database (Denmark)

2015-01-01

The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof.......The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof....

Sodium fire test at broad ranges of temperature and oxygen concentration. 4. Low temperature sodium spray fire tests

International Nuclear Information System (INIS)

Kawata, Koji; Miyahara, Shinya

2005-08-01

Sodium spray fire tests at the initial sodium temperature of 250degC were conducted under the atmospheric conditions of air and 3% oxygen containing nitrogen to determine the sodium burning rate and the aerosol release fraction and compare them with the test results at the initial sodium temperature of 500degC in air atmosphere. In the tests, sodium was supplied using a commercial spray nozzle into a stainless steel vessel of 100 m 3 volume (SOLFA-2). The sodium burning rate was calculated from two independent methods: the consumption rate of oxygen in the vessel and the enthalpy change of vessel components during the test. The aerosol release fraction was determined from the comparison between the measured aerosol concentrations and the calculated ones by the ABC-INTG code. The main conclusions were as follows, (1) In air atmosphere, a) sodium droplets ignited instantaneously and the spray fire was observed, and b) the sodium burning rate was about 440 g-Na/s and the fraction of supplied sodium was about 70%. (2) In 3% oxygen containing nitrogen, a) ignition of sodium droplets was not observed, and b) the sodium burning rate was about 44 g-Na/s and the fraction of supplied sodium was less than 10%. (author)

Carbon-hydrogen defects with a neighboring oxygen atom in n-type Si

Science.gov (United States)

Gwozdz, K.; Stübner, R.; Kolkovsky, Vl.; Weber, J.

2017-07-01

We report on the electrical activation of neutral carbon-oxygen complexes in Si by wet-chemical etching at room temperature. Two deep levels, E65 and E75, are observed by deep level transient spectroscopy in n-type Czochralski Si. The activation enthalpies of E65 and E75 are obtained as EC-0.11 eV (E65) and EC-0.13 eV (E75). The electric field dependence of their emission rates relates both levels to single acceptor states. From the analysis of the depth profiles, we conclude that the levels belong to two different defects, which contain only one hydrogen atom. A configuration is proposed, where the CH1BC defect, with hydrogen in the bond-centered position between neighboring C and Si atoms, is disturbed by interstitial oxygen in the second nearest neighbor position to substitutional carbon. The significant reduction of the CH1BC concentration in samples with high oxygen concentrations limits the use of this defect for the determination of low concentrations of substitutional carbon in Si samples.

Oxygen permeation modelling of perovskites

NARCIS (Netherlands)

van Hassel, Bart A.; van Hassel, B.A.; Kawada, Tatsuya; Sakai, Natsuko; Yokokawa, Harumi; Dokiya, Masayuki; Bouwmeester, Henricus J.M.

1993-01-01

A point defect model was used to describe the oxygen nonstoichiometry of the perovskites La0.75Sr0.25CrO3, La0.9Sr0.1FeO3, La0.9Sr0.1CoO3 and La0.8Sr0.2MnO3 as a function of the oxygen partial pressure. Form the oxygen vacancy concentration predicte by the point defect model, the ionic conductivity

In vivo integrated photoacoustic and confocal microscopy of hemoglobin oxygen saturation and oxygen partial pressure.

Science.gov (United States)

Wang, Yu; Hu, Song; Maslov, Konstantin; Zhang, Yu; Xia, Younan; Wang, Lihong V

2011-04-01

We developed dual-modality microscope integrating photoacoustic microscopy (PAM) and fluorescence confocal microscopy (FCM) to noninvasively image hemoglobin oxygen saturation (sO₂) and oxygen partial pressure (pO₂) in vivo in single blood vessels with high spatial resolution. While PAM measures sO₂ by imaging hemoglobin optical absorption at two wavelengths, FCM quantifies pO₂ using phosphorescence quenching. The variations of sO₂ and pO₂ values in multiple orders of vessel branches under hyperoxic (100% oxygen) and normoxic (21% oxygen) conditions correlate well with the oxygen-hemoglobin dissociation curve. In addition, the total concentration of hemoglobin is imaged by PAM at an isosbestic wavelength.

Measurement of oxygen transfer from air into organic solvents

DEFF Research Database (Denmark)

Ramesh, Hemalata; Mayr, Torsten; Hobisch, Mathias

2016-01-01

biological reactions require the supply of oxygen, most normally from air. However, reliable on-line measurements of oxygen concentration in organic solvents (and hence oxygen transfer rates from air to the solvent) has to date proven impossible due limitations in the current analytical methods. Results...... applications). Subsequently, we measured the oxygen transfer rates from air into these organic solvents. Conclusion The measurement of oxygen transfer rates from air into organic solvents using the dynamic method was established using the solvent resistant optical sensor. The feasibility of online oxygen...... For the first time, we demonstrate on-line oxygen measurements in non-aqueous media using a novel optical sensor. The sensor was used to measure oxygen concentration in various organic solvents including toluene, THF, isooctane, DMF, heptane and hexane (which have all been shown suitable for several biological...

Hydrostatic pressure effects on oxygen-related irradiation-produced defects in silicon

International Nuclear Information System (INIS)

Stein, H.J.; Samara, G.A.

1989-01-01

Hydrostatic pressure has been used to investigate the E c -0.164 eV acceptor level for the oxygen-vacancy (O-V) defect in γ-ray irradiated Si, and the annealing/formation of oxygen-related defects in neutron-irradiated Si. The acceptor level is found to move closer to the conduction band and away from the valence band. There is also a relatively large inward (outward) breathing mode lattice relaxation accompanying electron emission (capture) from this level. Both results reflect the antibonding nature of the level and are qualitatively consistent with the Watkins-Corbett model for the O-V defect. The annealing rate was found to increase with pressure for the O-V defect at 350 0 C with a derived activation volume of -4.5A 3 /defect, where the negative sign implies inward relaxation (contraction) on annealing. Pressure has relatively little effect on annealing of the C-Si-O C(3) defect which is interstitial in nature, but strongly favors the formation of the dioxygen defect. The intensity of the O 2 -V band after annealing at 20 kbar is 5 times higher than that following similar annealing at 0 kbar. This intensity is higher than that achievable by any isochronal or isothermal annealing steps at 0 kbar. These results are discussed qualitatively in terms of models for the various defects. (author)

Detection of atomic oxygen in flames by absorption spectroscopy

International Nuclear Information System (INIS)

Cheskis, S.; Kovalenko, S.A.

1994-01-01

The absolute concentration of atomic oxygen in an atmospheric pressure hydrogen/air flame has been measured using Intracavity Laser Spectroscopy (ICLS) based on a dye laser pumped by an argon-ion laser. Absorptions at the highly forbidden transitions at 630.030 nm and 636.380 nm were observed at an equivalent optical length of up to 10 km. The relatively low intensity of the dye laser avoids photochemical interferences that are inherent to some other methods for detecting atomic oxygen. The detection sensitivity is about 6x10 14 atom/cm 3 and can be improved with better flame and laser stabilization. (orig.)

Roles of Bulk and Surface Chemistry in the Oxygen Exchange Kinetics and Related Properties of Mixed Conducting Perovskite Oxide Electrodes

Directory of Open Access Journals (Sweden)

Nicola H. Perry

2016-10-01

Full Text Available Mixed conducting perovskite oxides and related structures serving as electrodes for electrochemical oxygen incorporation and evolution in solid oxide fuel and electrolysis cells, respectively, play a significant role in determining the cell efficiency and lifetime. Desired improvements in catalytic activity for rapid surface oxygen exchange, fast bulk transport (electronic and ionic, and thermo-chemo-mechanical stability of oxygen electrodes will require increased understanding of the impact of both bulk and surface chemistry on these properties. This review highlights selected work at the International Institute for Carbon-Neutral Energy Research (I2CNER, Kyushu University, set in the context of work in the broader community, aiming to characterize and understand relationships between bulk and surface composition and oxygen electrode performance. Insights into aspects of bulk point defect chemistry, electronic structure, crystal structure, and cation choice that impact carrier concentrations and mobilities, surface exchange kinetics, and chemical expansion coefficients are emerging. At the same time, an understanding of the relationship between bulk and surface chemistry is being developed that may assist design of electrodes with more robust surface chemistries, e.g., impurity tolerance or limited surface segregation. Ion scattering techniques (e.g., secondary ion mass spectrometry, SIMS, or low energy ion scattering spectroscopy, LEIS with high surface sensitivity and increasing lateral resolution are proving useful for measuring surface exchange kinetics, diffusivity, and corresponding outer monolayer chemistry of electrodes exposed to typical operating conditions. Beyond consideration of chemical composition, the use of strain and/or a high density of active interfaces also show promise for enhancing performance.

A Compact Medical Oxygen Generator for Spacecraft, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — An on-board oxygen concentrator is required during long duration manned space missions to supply medical oxygen. Commercial medical oxygen generators are pressure...

Experimental study on ceramic membrane technology for onboard oxygen generation

Directory of Open Access Journals (Sweden)

Jiang Dongsheng

2016-08-01

Full Text Available The ceramic membrane oxygen generation technology has advantages of high concentration of produced oxygen and potential nuclear and biochemical protection capability. The present paper studies the ceramic membrane technology for onboard oxygen generation. Comparisons are made to have knowledge of the effects of two kinds of ceramic membrane separation technologies on oxygen generation, namely electricity driven ceramic membrane separation oxygen generation technology (EDCMSOGT and pressure driven ceramic membrane separation oxygen generation technology (PDCMSOGT. Experiments were conducted under different temperatures, pressures of feed air and produced oxygen flow rates. On the basis of these experiments, the flow rate of feed air, electric power provided, oxygen recovery rate and concentration of produced oxygen are compared under each working condition. It is concluded that the EDCMSOGT is the oxygen generation means more suitable for onboard conditions.

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

Science.gov (United States)

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.

Seasonal and interannual variability of dissolved oxygen around the Balearic Islands from hydrographic data

Science.gov (United States)

Balbín, R.; López-Jurado, J. L.; Aparicio-González, A.; Serra, M.

2014-10-01

Oceanographic data obtained between 2001 and 2011 by the Spanish Institute of Oceanography (IEO, Spain) have been used to characterise the spatial distribution and the temporal variability of the dissolved oxygen around the Balearic Islands (Mediterranean Sea). The study area includes most of the Western Mediterranean Sea, from the Alboran Sea to Cape Creus, at the border between France and Spain. Dissolved oxygen (DO) at the water surface is found to be in a state of equilibrium exchange with the atmosphere. In the spring and summer a subsurface oxygen supersaturation is observed due to the biological activity, above the subsurface fluorescence maximum. Minimum observed values of dissolved oxygen are related to the Levantine Intermediate Waters (LIW). An unusual minimum of dissolved oxygen concentrations was also recorded in the Alboran Sea Oxygen Minimum Zone. The Western Mediterranean Deep Waters (WMDW) and the Western Intermediate Waters (WIW) show higher values of dissolved oxygen than the Levantine Intermediate Waters due to their more recent formation. Using these dissolved oxygen concentrations it is possible to show that the Western Intermediate Waters move southwards across the Ibiza Channel and the deep water circulates around the Balearic Islands. It has also been possible to characterise the seasonal evolution of the different water masses and their dissolved oxygen content in a station in the Algerian sub-basin.

The oxycoal process with cryogenic oxygen supply

Science.gov (United States)

Kather, Alfons; Scheffknecht, Günter

2009-09-01

Due to its large reserves, coal is expected to continue to play an important role in the future. However, specific and absolute CO2 emissions are among the highest when burning coal for power generation. Therefore, the capture of CO2 from power plants may contribute significantly in reducing global CO2 emissions. This review deals with the oxyfuel process, where pure oxygen is used for burning coal, resulting in a flue gas with high CO2 concentrations. After further conditioning, the highly concentrated CO2 is compressed and transported in the liquid state to, for example, geological storages. The enormous oxygen demand is generated in an air-separation unit by a cryogenic process, which is the only available state-of-the-art technology. The generation of oxygen and the purification and liquefaction of the CO2-enriched flue gas consumes significant auxiliary power. Therefore, the overall net efficiency is expected to be lowered by 8 to 12 percentage points, corresponding to a 21 to 36% increase in fuel consumption. Oxygen combustion is associated with higher temperatures compared with conventional air combustion. Both the fuel properties as well as limitations of steam and metal temperatures of the various heat exchanger sections of the steam generator require a moderation of the temperatures during combustion and in the subsequent heat-transfer sections. This is done by means of flue gas recirculation. The interdependencies among fuel properties, the amount and the temperature of the recycled flue gas, and the resulting oxygen concentration in the combustion atmosphere are investigated. Expected effects of the modified flue gas composition in comparison with the air-fired case are studied theoretically and experimentally. The different atmosphere resulting from oxygen-fired combustion gives rise to various questions related to firing, in particular, with regard to the combustion mechanism, pollutant reduction, the risk of corrosion, and the properties of the fly

The oxycoal process with cryogenic oxygen supply.

Science.gov (United States)

Kather, Alfons; Scheffknecht, Günter

2009-09-01

Due to its large reserves, coal is expected to continue to play an important role in the future. However, specific and absolute CO2 emissions are among the highest when burning coal for power generation. Therefore, the capture of CO2 from power plants may contribute significantly in reducing global CO2 emissions. This review deals with the oxyfuel process, where pure oxygen is used for burning coal, resulting in a flue gas with high CO2 concentrations. After further conditioning, the highly concentrated CO2 is compressed and transported in the liquid state to, for example, geological storages. The enormous oxygen demand is generated in an air-separation unit by a cryogenic process, which is the only available state-of-the-art technology. The generation of oxygen and the purification and liquefaction of the CO2-enriched flue gas consumes significant auxiliary power. Therefore, the overall net efficiency is expected to be lowered by 8 to 12 percentage points, corresponding to a 21 to 36% increase in fuel consumption. Oxygen combustion is associated with higher temperatures compared with conventional air combustion. Both the fuel properties as well as limitations of steam and metal temperatures of the various heat exchanger sections of the steam generator require a moderation of the temperatures during combustion and in the subsequent heat-transfer sections. This is done by means of flue gas recirculation. The interdependencies among fuel properties, the amount and the temperature of the recycled flue gas, and the resulting oxygen concentration in the combustion atmosphere are investigated. Expected effects of the modified flue gas composition in comparison with the air-fired case are studied theoretically and experimentally. The different atmosphere resulting from oxygen-fired combustion gives rise to various questions related to firing, in particular, with regard to the combustion mechanism, pollutant reduction, the risk of corrosion, and the properties of the fly

Catalyst evaluation for oxygen reduction reaction in concentrated phosphoric acid at elevated temperatures

Science.gov (United States)

Hu, Yang; Jiang, Yiliang; Jensen, Jens Oluf; Cleemann, Lars N.; Li, Qingfeng

2018-01-01

Phosphoric acid is the common electrolyte for high-temperature polymer electrolyte fuel cells (HT-PEMFCs) that have advantages such as enhanced CO tolerance and simplified heat and water management. The currently used rotating disk electrode technique is limited to tests in dilute solutions at low temperatures and hence is not suitable for catalyst evaluation for HT-PEMFCs. In this study, we have designed and constructed a half-cell setup to measure the intrinsic activities of catalysts towards the oxygen reduction reaction (ORR) in conditions close to HT-PEMFC cathodes. By optimization of the hydrophobic characteristics of electrodes and the catalyst layer thickness, ORR activities of typical Pt/C catalysts are successfully measured in concentrated phosphoric acid at temperatures above 100 °C. In terms of mass-specific activities, the catalyst exhibits about two times higher activity in the half-cell electrode than that observed in fuel cells, indicating the feasibility of the technique as well as the potential for further improvement of fuel cell electrode performance.

The oxygen effect and cellular adaptation

International Nuclear Information System (INIS)

Meshcherikova, V.V.; Vajnson, A.A.; Yarmonenko, S.P.

1979-01-01

The radiomodifying effect of oxygen was shown to depend on the level of cellular oxygenation prior to irradiation. Acute hypoxia created at the time of irradiation protects previously normally oxygenated cells with DMF approximately 1.4 times larger than that of cells cultured for 24 hours under conditions of mild hypoxia. It is suggested that a decrease in the radioprotective effect of acute hypoxia on chronically hypoxic cells is correlated with an appreciable decrease in the rate of oxygen consumption by these cells, due to which the oxygen concentration near the intracellular targets in chronically hypoxic cells may be higher than in normal cells under conditions of poor oxygenation

Oxygen requirement of separated hybrid catfish eggs

Science.gov (United States)

Channel catfish egg masses require hatchery water with over 7.8 ppm dissolved oxygen at 80° F (95% air saturation) to maintain maximum oxygen consumption as they near hatching. This concentration is called the critical oxygen requirement by scientists but for the purpose of this article we will call...

Effects of the oxygenation level on formation of different reactive oxygen species during photodynamic therapy.

Science.gov (United States)

Price, Michael; Heilbrun, Lance; Kessel, David

2013-01-01

We examined the effect of the oxygenation level on efficacy of two photosensitizing agents, both of which target lysosomes for photodamage, but via different photochemical pathways. Upon irradiation, the chlorin termed NPe6 forms singlet oxygen in high yield while the bacteriopheophorbide WST11 forms only oxygen radicals (in an aqueous environment). Photokilling efficacy by WST11 in cell culture was impaired when the atmospheric oxygen concentration was reduced from 20% to 1%, while photokilling by NPe6 was unaffected. Studies in a cell-free system revealed that the rates of photobleaching of these agents, as a function of the oxygenation level, were correlated with results described above. Moreover, the rate of formation of oxygen radicals by either agent was more sensitive to the level of oxygenation than was singlet oxygen formation by NPe6. These data indicate that the photochemical process that leads to oxygen radical formation is more dependent on the oxygenation level than is the pathway leading to formation of singlet oxygen. © 2013 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2013 The American Society of Photobiology.

Ethanol flame synthesis of carbon nanotubes in deficient oxygen environments

Science.gov (United States)

Hu, Wei-Chieh; Lin, Ta-Hui

2016-04-01

In this study, carbon nanotubes (CNTs) were synthesized using ethanol diffusion flames in a stagnation-flow system composed of an upper oxidizer duct and a lower liquid pool. In the experiments, a gaseous mixture of oxygen and nitrogen flowed from the upper oxidizer duct, and then impinged onto the vertically aligned ethanol pool to generate a planar and steady diffusion flame in a deficient oxygen environment. A nascent nickel mesh was used as the catalytic metal substrate to collect deposited materials. The effect of low oxygen concentration on the formation of CNTs was explored. The oxygen concentration significantly influenced the flame environment and thus the synthesized carbon products. Lowering the oxygen concentration increased the yield, diameter, and uniformity of CNTs. The optimal operating conditions for CNT synthesis were an oxygen concentration in the range of 15%-19%, a flame temperature in the range of 460 °C-870 °C, and a sampling position of 0.5-1 mm below the upper edge of the blue flame front. It is noteworthy that the concentration gradient of C2 species and CO governed the CNT growth directly. CNTs were successfully fabricated in regions with uniform C2 species and CO distributions.

Reaeration of oxygen in shallow, macrophyte rich streams. 1

International Nuclear Information System (INIS)

Thyssen, N.; Erlandsen, M.; Jeppesen, E.

1987-01-01

The rate coefficient K 2 for the exchange of oxygen between flowing water and the atmosphere (reaeration) has been studied in six Danish streams covering a relatively wide range of hydraulic conditions, pollutional loading, and macrophyte abundance. 103 K 2 measurements were performed in 1978-85. 82 measurements were obtained applying 5 different indirect methods all balancing the sources and sinks of stream dissolved oxygen under conditions of normal operation of the system (3 methods) and under artificial depletion of the oxygen concentration of the stream water by addition of sodium sulfite (2 methods). 21 K 2 values were determined directly applying the gaseous tracer 85 Kr for reaeration. Guidelines for selecting a proper method to determine K 2 knowing macrophyte biomass and loading characteristics of the particular stream are provided. (author)

Real-Time Monitoring of Singlet Oxygen and Oxygen Partial Pressure During the Deep Photodynamic Therapy In Vitro.

Science.gov (United States)

Li, Weitao; Huang, Dong; Zhang, Yan; Liu, Yangyang; Gu, Yueqing; Qian, Zhiyu

2016-09-01

Photodynamic therapy (PDT) is an effective noninvasive method for the tumor treatment. The major challenge in current PDT research is how to quantitatively evaluate therapy effects. To our best knowledge, this is the first time to combine multi-parameter detection methods in PDT. More specifically, we have developed a set of system, including the high-sensitivity measurement of singlet oxygen, oxygen partial pressure and fluorescence image. In this paper, the detection ability of the system was validated by the different concentrations of carbon quantum dots. Moreover, the correlation between singlet oxygen and oxygen partial pressure with laser irradiation was observed. Then, the system could detect the signal up to 0.5 cm tissue depth with 660 nm irradiation and 1 cm tissue depth with 980 nm irradiation by using up-conversion nanoparticles during PDT in vitro. Furthermore, we obtained the relationship among concentration of singlet oxygen, oxygen partial pressure and tumor cell viability under certain conditions. The results indicate that the multi-parameter detection system is a promising asset to evaluate the deep tumor therapy during PDT. Moreover, the system might be potentially used for the further study in biology and molecular imaging.

Instrumented impact properties of zircaloy-oxygen and zircaloy-hydrogen alloys

Energy Technology Data Exchange (ETDEWEB)

Garde, A.M.; Kassner, T.F.

1980-04-01

Instrumented-impact tests were performed on subsize Charpy speciments of Zircaloy-2 and -4 with up to approx. 1.3 wt % oxygen and approx. 2500 wt ppM hydrogen at temperatures between 373 and 823/sup 0/K. Self-consistent criteria for the ductile-to-brittle transition, based upon a total absorbed energy of approx. 1.3 x 10/sup 4/ J/m/sup 2/, a dynamic fracture toughness of approx. 10 MPa.m/sup 1/2/, and a ductility index of approx. 0, were established relative to the temperature and oxygen concentration of the transformed BETA-phase material. The effect of hydrogen concentration and hydride morphology, produced by cooling Zircaloy-2 specimens through the temperature range of the BETA ..-->.. ..cap alpha..' = hydride phase transformation at approx. 0.3 and 3 K/s, on the impact properties was determined at temperatures between 373 and 673 K. On an atom fraction basis, oxygen has a greater effect than hydrogen on the impact properties of Zircaloy at temperatures between approx. 400 and 600 K. 34 figures.

Dissolved hydrogen and oxygen sensors using semiconductor devices

International Nuclear Information System (INIS)

Hara, Nobuyoshi; Sugimoto, Katsuhisa

1995-01-01

The concentrations of DH and DO in aqueous solution are the factors that determine the equilibrium potential of hydrogen and oxygen electrode reactions, respectively, and are the quantities which directly related to the rates of hydrogen generation type and oxygen consumption type corrosion reactions, therefore, they have the important meaning in the electrochemistry of corrosion. In the hydrogen injection into BWR cooling water, the concentration of hydrogen must be controlled strictly, accordingly DH and DO sensors and electrochemical potential sensors are required. For the chemical sensors used in reactor cooling water, the perfectly solid state sensors made of high corrosion resistance materials, which are small size and withstand high temperature and high pressure, must be developed. The structure and the characteristics of the semiconductor devices used as gas sensors, and the principles of DH and DO sensors are described. If the idea of porous or discontinuous membrane gate is developed, the ion sensor of solid structure with one-body reference electrode may be made. (K.I.)

Element Distribution in the Oxygen-Rich Side-Blow Bath Smelting of a Low-Grade Bismuth-Lead Concentrate

Science.gov (United States)

Yang, Tianzu; Xiao, Hui; Chen, Lin; Chen, Wei; Liu, Weifeng; Zhang, Duchao

2018-03-01

Oxygen-rich side-blow bath smelting (OSBS) technology offers an efficient method for processing complex bismuth-lead concentrates; however, the element distributions in the process remain unclear. This work determined the distributions of elements, i.e., bismuth, lead, silver, copper, arsenic and antimony, in an industrial-scale OSBS process. The feed, oxidized slag and final products were collected from the respective sampling points and analyzed. For the oxidative smelting process, 65% of bismuth and 76% of silver in the concentrate report to the metal alloy, whereas less lead reports to the metal ( 31%) than the oxidized slag ( 44%). Approximately 50% of copper enters the matte, while more than 63% of arsenic and antimony report to the slag. For the reductive smelting process, less than 4.5% of bismuth, lead, silver and copper in the oxidized slag enter the reduced slag, indicating high recoveries of these metal values.

Correlation between air flow rate and pollutant concentrations during two-stage oak log combustion in a 25 KW residential boiler

Directory of Open Access Journals (Sweden)

Juszczak Marek

2016-09-01

Full Text Available It can be expected that there is a considerable correlation between combustion air flow rate and the concentrations of carbon monoxide, hydrocarbons and nitrogen oxide in the flue gas. The influence of temperature and oxygen concentration in the combustion zone on the concentrations of carbon monoxide, hydrocarbons and nitrogen oxide in the flue gas, for high and low combustion air flow, was analysed. Oxygen concentration for which the concentration of carbon monoxide is the lowest was determined, as well as the mutual relation between carbon monoxide and nitrogen oxide concentration.

Dissolved oxygen sensing using organometallic dyes deposited within a microfluidic environment

Science.gov (United States)

Chen, Q. L.; Ho, H. P.; Jin, L.; Chu, B. W.-K.; Li, M. J.; Yam, V. W.-W.

2008-02-01

This work primarily aims to integrate dissolved oxygen sensing capability with a microfluidic platform containing arrays of micro bio-reactors or bio-activity indicators. The measurement of oxygen concentration is of significance for a variety of bio-related applications such as cell culture and gene expression. Optical oxygen sensors based on luminescence quenching are gaining much interest in light of their low power consumption, quick response and high analyte sensitivity in comparison to similar oxygen sensing devices. In our microfluidic oxygen sensor device, a thin layer of oxygen-sensitive luminescent organometallic dye is covalently bonded to a glass slide. Micro flow channels are formed on the glass slide using patterned PDMS (Polydimethylsiloxane). Dissolved oxygen sensing is then performed by directing an optical excitation probe beam to the area of interest within the microfluidic channel. The covalent bonding approach for sensor layer formation offers many distinct advantages over the physical entrapment method including minimizing dye leaching, ensuring good stability and fabrication simplicity. Experimental results confirm the feasibility of the device.

Oxygen 18 concentration profile measurements near the surface by 18O(p,α)15N resonance reaction

International Nuclear Information System (INIS)

Amsel, G.; David, D.

1975-01-01

The method of spectrum reduction in nuclear reaction microanalysis does not allow to obtain depth resolutions better than the order of 2000A. Resolutions of the order of 200A may be obtained by using the narrow resonance technique, when applied to thin films. The latter technique was extended to thick targets, with deep concentration profiles presenting a sharp gradient near the surface. This method is presented and illustrated by the study of 18 O profiles in oxygen diffusion measurements in growing ZrO 2 , using the 629keV resonance of the reaction 18 O(p,α) 15 N [fr

Aberrant patterns of X chromosome inactivation in a new line of human embryonic stem cells established in physiological oxygen concentrations.

Science.gov (United States)

de Oliveira Georges, Juliana Andrea; Vergani, Naja; Fonseca, Simone Aparecida Siqueira; Fraga, Ana Maria; de Mello, Joana Carvalho Moreira; Albuquerque, Maria Cecília R Maciel; Fujihara, Litsuko Shimabukuro; Pereira, Lygia Veiga

2014-08-01

One of the differences between murine and human embryonic stem cells (ESCs) is the epigenetic state of the X chromosomes in female lines. Murine ESCs (mESCs) present two transcriptionally active Xs that will undergo the dosage compensation process of XCI upon differentiation, whereas most human ESCs (hESCs) spontaneously inactivate one X while keeping their pluripotency. Whether this reflects differences in embryonic development of mice and humans, or distinct culture requirements for the two kinds of pluripotent cells is not known. Recently it has been shown that hESCs established in physiological oxygen levels are in a stable pre-XCI state equivalent to that of mESCs, suggesting that culture in low oxygen concentration is enough to preserve that epigenetic state of the X chromosomes. Here we describe the establishment of two new lines of hESCs under physiological oxygen level and the characterization of the XCI state in the 46,XX line BR-5. We show that a fraction of undifferentiated cells present XIST RNA accumulation and single H3K27me foci, characteristic of the inactive X. Moreover, analysis of allele specific gene expression suggests that pluripotent BR-5 cells present completely skewed XCI. Our data indicate that physiological levels of oxygen are not sufficient for the stabilization of the pre-XCI state in hESCs.

Oxygen vacancies enabled enhancement of catalytic property of Al reduced anatase TiO{sub 2} in the decomposition of high concentration ozone

Energy Technology Data Exchange (ETDEWEB)

Ding, Yanhua; Zhang, Xiaolei [Shanghai Institute of Technology, Shanghai 200235 (China); Chen, Li [East China Normal University, Shanghai 200062 (China); Wang, Xiaorui [Shanghai Institute of Technology, Shanghai 200235 (China); Zhang, Na, E-mail: nzhang@sit.edu.cn [Shanghai Institute of Technology, Shanghai 200235 (China); Liu, Yufeng [Shanghai Institute of Technology, Shanghai 200235 (China); Fang, Yongzheng, E-mail: fyz1003@sina.com [Shanghai Institute of Technology, Shanghai 200235 (China)

2017-06-15

The catalytic decomposition of gaseous ozone (O{sub 3}) is investigated using anatase TiO{sub 2} (A-TiO{sub 2}) and Aluminum-reduced A-TiO{sub 2} (ARA-TiO{sub 2}) at high concentration and high relative humidity (RH) without light illumination. Compared with the pristine A-TiO{sub 2}, the ARA-TiO{sub 2} sample possesses a unique crystalline core-amorphous shell structure. It is proved to be an excellent solar energy “capture” for solar thermal collectors due to lots of oxygen vacancies. The results indicate that the overall decomposition efficiency of O{sub 3} without any light irradiation has been greatly improved from 4.8% on A-TiO{sub 2} to 100% on ARA-TiO{sub 2} under the RH=100% condition. The ozone conversion over T500/ARA-TiO{sub 2} catalyst is still maintained at 95% after a 72 h test under the reaction condition of 18.5 g/m{sup 3} ozone initial concentration, and RH=90%. The results can be explained that T500/ARA-TiO{sub 2} possesses the largest amorphous contour, the lowest crystallinity, the most surface-active Ti{sup 3+}/T{sup i4+}couples, and the most oxygen vacancies. This result opens a new door to widen the application of TiO{sub 2} in the thermal-catalytic field. - Graphical abstract: The anatase-TiO{sub 2} with various oxidation states and oxygen vacancies have been obtained by aluminum-reduction, and the decomposition efficiency of O{sub 3} has been greatly improved from 4.8% to 100% without irradiation under the RH=100% condition. - Highlights: • The decomposition of gaseous ozone over Al reduced TiO2 (ARA-TiO{sub 2}) is firstly reported. • The decomposition efficiency is up to 100% without any light irradiation on ARA-TiO{sub 2} under RH=100% condition. • The ozone conversion is maintained at 95% after a 72 h test, when C{sub inlet}=18.5 g/m{sup 3} and RH=90%.

Oxygen plasma etching of silver-incorporated diamond-like carbon films

International Nuclear Information System (INIS)

Marciano, F.R.; Bonetti, L.F.; Pessoa, R.S.; Massi, M.; Santos, L.V.; Trava-Airoldi, V.J.

2009-01-01

Diamond-like carbon (DLC) film as a solid lubricant coating represents an important area of investigation related to space devices. The environment for such devices involves high vacuum and high concentration of atomic oxygen. The purpose of this paper is to study the behavior of silver-incorporated DLC thin films against oxygen plasma etching. Silver nanoparticles were produced through an electrochemical process and incorporated into DLC bulk during the deposition process using plasma enhanced chemical vapor deposition technique. The presence of silver does not affect significantly DLC quality and reduces by more than 50% the oxygen plasma etching. Our results demonstrated that silver nanoparticles protect DLC films against etching process, which may increase their lifetime in low earth orbit environment.

Oxygen plasma etching of silver-incorporated diamond-like carbon films

Energy Technology Data Exchange (ETDEWEB)

Marciano, F.R., E-mail: fernanda@las.inpe.b [Instituto Nacional de Pesquisas Espaciais (INPE), Laboratorio Associado de Sensores e Materiais (LAS), Av. dos Astronautas 1758, Sao Jose dos Campos, 12227-010, SP (Brazil); Instituto Tecnologico de Aeronautica (ITA), Centro Tecnico Aeroespacial (CTA), Pca. Marechal Eduardo Gomes, 50-Sao Jose dos Campos, 12228-900, SP (Brazil); Bonetti, L.F. [Clorovale Diamantes Industria e Comercio Ltda, Estr. do Torrao de Ouro, 500-Sao Jose dos Campos, 12229-390, SP (Brazil); Pessoa, R.S.; Massi, M. [Instituto Tecnologico de Aeronautica (ITA), Centro Tecnico Aeroespacial (CTA), Pca. Marechal Eduardo Gomes, 50-Sao Jose dos Campos, 12228-900, SP (Brazil); Santos, L.V.; Trava-Airoldi, V.J. [Instituto Nacional de Pesquisas Espaciais (INPE), Laboratorio Associado de Sensores e Materiais (LAS), Av. dos Astronautas 1758, Sao Jose dos Campos, 12227-010, SP (Brazil)

2009-08-03

Diamond-like carbon (DLC) film as a solid lubricant coating represents an important area of investigation related to space devices. The environment for such devices involves high vacuum and high concentration of atomic oxygen. The purpose of this paper is to study the behavior of silver-incorporated DLC thin films against oxygen plasma etching. Silver nanoparticles were produced through an electrochemical process and incorporated into DLC bulk during the deposition process using plasma enhanced chemical vapor deposition technique. The presence of silver does not affect significantly DLC quality and reduces by more than 50% the oxygen plasma etching. Our results demonstrated that silver nanoparticles protect DLC films against etching process, which may increase their lifetime in low earth orbit environment.

Modeling and experimental methods to predict oxygen distribution in bone defects following cell transplantation.

Science.gov (United States)

Heylman, Christopher M; Santoso, Sharon; Krebs, Melissa D; Saidel, Gerald M; Alsberg, Eben; Muschler, George F

2014-04-01

We have developed a mathematical model that allows simulation of oxygen distribution in a bone defect as a tool to explore the likely effects of local changes in cell concentration, defect size or geometry, local oxygen delivery with oxygen-generating biomaterials (OGBs), and changes in the rate of oxygen consumption by cells within a defect. Experimental data for the oxygen release rate from an OGB and the oxygen consumption rate of a transplanted cell population are incorporated into the model. With these data, model simulations allow prediction of spatiotemporal oxygen concentration within a given defect and the sensitivity of oxygen tension to changes in critical variables. This information may help to minimize the number of experiments in animal models that determine the optimal combinations of cells, scaffolds, and OGBs in the design of current and future bone regeneration strategies. Bone marrow-derived nucleated cell data suggest that oxygen consumption is dependent on oxygen concentration. OGB oxygen release is shown to be a time-dependent function that must be measured for accurate simulation. Simulations quantify the dependency of oxygen gradients in an avascular defect on cell concentration, cell oxygen consumption rate, OGB oxygen generation rate, and OGB geometry.

In situ measurements of oxygen dynamics in unsaturated archaeological deposits

DEFF Research Database (Denmark)

Matthiesen, Henning; Hollesen, Jørgen; Dunlop, Rory

2015-01-01

Oxygen is a key parameter in the degradation of archaeological material, but little is known of its dynamics in situ. In this study, 10 optical oxygen sensors placed in a 2 m deep test pit in the cultural deposits at Bryggen in Bergen have monitored oxygen concentrations every half hour for more ...... of the soil exceeds 10–15% vol, while oxygen dissolved in infiltrating rainwater is of less importance for the supply of oxygen in the unsaturated zone....... than a year. It is shown that there is a significant spatial and temporal variation in the oxygen concentration, which is correlated to measured soil characteristics, precipitation, soil water content and degradation of organic material. In these deposits oxygen typically occurs when the air content...

Glow discharge in singlet oxygen

International Nuclear Information System (INIS)

Vagin, N.P.; Ionin, A.A.; Klimachev, Yu.M.; Sinitsyn, D.V.; Yuryshev, N.N.; Kochetov, I.V.; Napartovich, A.P.

2003-01-01

Currently, there is no experimental data on the plasma balance in gas mixtures with a high content of singlet delta oxygen O 2 ( 1 Δ g ). These data can be obtained by studying the parameters of an electric discharge in singlet oxygen produced by a chemical generator. The O 2 ( 1 Δ g ) molecules significantly change the kinetics of electrons and negative ions in plasma. Hence, the discharge conditions at low and high O 2 ( 1 Δ g ) concentrations are very different. Here, the parameters of the positive column of a glow discharge in a gas flow from a chemical singlet-oxygen generator are studied. It is experimentally shown that, at an O 2 ( 1 Δ g ) concentration of 50% and at pressures of 1.5 and 2 torr, the electric field required to sustain the discharge is considerably lower than in the case when all of the oxygen molecules are in the ground state. A theoretical model of the glow discharge is proposed whose predictions are in good agreement with the experimental data

Determination, through titration with NO, of the concentration of oxygen atoms in the flowing afterglow of Ar-O2 and N2-O2 plasmas used for sterilization purposes

Science.gov (United States)

Ricard, A.; Moisan, M.; Moreau, S.

2001-04-01

Les méthodes existantes de titrage de N et O d'une post-décharge au moyen de l'intensité d'émission de la molécule NO excitée ne permettant pas d'aller au-delà de x = 5% dans un mélange xO2-(100%-x)N2, nous présentons une démarche valable pour x≤20%. Cette technique est fondée sur la mesure de l'intensité d'émission de NO2(A), en fonction du débit de NO introduit, en relation avec une dérivation analytique des équations des concentrations [N] et [O]. La concentration d'oxygène atomique obtenue par cette méthode est validée de façon indépendante à partir de la mesure du rapport des intensités d'émission de NO(B) et de N2(B, 11) (celle-ci détectable pour x≤8%). Enfin, la méthode proposée est mise en oeuvre pour apprécier l'influence de la valeur de la concentration d'oxygène atomique sur le temps de stérilisation dans une post-décharge en flux à partir d'un plasma de N2-O2. \\engabstract Existing titration methods of N and O in an afterglow based on the emission intensity of the excited NO molecule cannot be used at x values exceeding 5% in the xO2-(100%-x)N2 mixture. Our technique extends the x range to 20%. It utilizes the emission intensity measurement of NO2(A), as a function of the introduced NO flow, in relation with analytically derived equations for the O and N concentrations. The atomic oxygen concentration obtained in this way is validated independently through measurements of the emission intensity ratio of NO(B) and N2(B, 11) (detectable for x≤8%). Finally, the proposed method is used to assess the influence of the oxygen atom concentration on the sterilization time in the flowing afterglow of an N2-O2 plasma.

Influence of nitrogen oxides NO and NO2 on singlet delta oxygen production in pulsed discharge

International Nuclear Information System (INIS)

Ionin, A A; Klimachev, Yu M; Kozlov, A Yu; Kotkov, A A; Rulev, O A; Seleznev, L V; Sinitsyn, D V; Vagin, N P; Yuryshev, N N; Kochetov, I V; Napartovich, A P

2009-01-01

The influence of nitrogen oxides NO and NO 2 on the specific input energy (SIE) and the time behaviour of singlet delta oxygen (SDO) luminescence excited by a pulsed e-beam sustained discharge in oxygen were experimentally and theoretically studied. NO and NO 2 addition into oxygen results in a small increase and decrease in the SIE, respectively, the latter being connected with a large energy of electron affinity to NO 2 . The addition of 0.1-0.3% nitrogen oxides was experimentally and theoretically demonstrated to result in a notable enhancement of the SDO lifetime, which is related to a decrease in the atomic oxygen concentration in afterglow. It was experimentally demonstrated that to get a high SDO concentration at the gas pressure 30-60 Torr for a time interval of less than ∼0.5 s one needs to add not less than 0.2% nitrogen oxides into oxygen. The temperature dependence of the relaxation constant for SDO quenching by unexcited oxygen was estimated by using experimental data on the time behaviour of SDO luminescence.

Suppression of aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} by reducing dissolved oxygen concentration for high-performance magnetic refrigeration

Energy Technology Data Exchange (ETDEWEB)

Fujieda, S., E-mail: fujieda@tagen.tohoku.ac.jp; Fukamichi, K.; Suzuki, S.

2014-07-05

Highlights: • The aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} and its suppression were investigated. • The lattice expansion after immersion was caused by the hydrogen absorption. • The itinerant-electron metamagnetic transition became indistinct after immersion. • The aqueous corrosion was suppressed by reducing the dissolved oxygen concentration. - Abstract: The itinerant-electron metamagnetic transition of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} becomes indistinct after immersion in distilled-water containing about 8 ppm of the dissolved oxygen (DO) concentration because of aqueous corrosion. However, the aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} is significantly suppressed by reducing the DO concentration. Thus, isothermal magnetic entropy change after immersion for 30 days in deaerated distilled-water with a DO concentration less than 0.1 ppm is larger than that after immersion for 5 days in distilled-water containing about 8 ppm of the DO concentration. Consequently, the reduction of the DO concentration is effective for preservation of the excellent magnetocaloric effects of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} in an aqueous solution, which is a promising heat transfer fluid of room-temperature magnetic refrigeration.

White Matter Damage Relates to Oxygen Saturation in Children With Sickle Cell Anemia Without Silent Cerebral Infarcts.

Science.gov (United States)

Kawadler, Jamie M; Kirkham, Fenella J; Clayden, Jonathan D; Hollocks, Matthew J; Seymour, Emma L; Edey, Rosanna; Telfer, Paul; Robins, Andrew; Wilkey, Olu; Barker, Simon; Cox, Tim C S; Clark, Chris A

2015-07-01

Sickle cell anemia is associated with compromised oxygen-carrying capability of hemoglobin and a high incidence of overt and silent stroke. However, in children with no evidence of cerebral infarction, there are changes in brain morphometry relative to healthy controls, which may be related to chronic anemia and oxygen desaturation. A whole-brain tract-based spatial statistics analysis was carried out in 25 children with sickle cell anemia with no evidence of abnormality on T2-weighted magnetic resonance imaging (13 male, age range: 8-18 years) and 14 age- and race-matched controls (7 male, age range: 10-19 years) to determine the extent of white matter injury. The hypotheses that white matter damage is related to daytime peripheral oxygen saturation and steady-state hemoglobin were tested. Fractional anisotropy was found to be significantly lower in patients in the subcortical white matter (corticospinal tract and cerebellum), whereas mean diffusivity and radial diffusivity were higher in patients in widespread areas. There was a significant negative relationship between radial diffusivity and oxygen saturation (Plevel negative relationship between radial diffusivity and hemoglobin (Pcell anemia, and provides for the first time direct evidence of a relationship between brain microstructure and markers of disease severity (eg, peripheral oxygen saturation and steady-state hemoglobin). This study suggests that diffusion tensor imaging metrics may serve as a biomarker for future trials of reducing hypoxic exposure. © 2015 American Heart Association, Inc.

Widespread functional anoxia in the oxygen minimum zone of the Eastern South Pacific

Science.gov (United States)

Thamdrup, Bo; Dalsgaard, Tage; Revsbech, Niels Peter

Oxygen minimum zones (OMZs) as found in the Eastern Pacific and Indian Ocean are biogeochemical hot spots with a disproportionately large role in the marine nitrogen cycle, and they are important components of the highly productive ecosystems in which they occur. Although the oxygen-depleted waters have been known for a century, oxygen levels inside them are not well constrained and the regulation of their anaerobic processes by oxygen is poorly understood. We deployed highly sensitive STOX oxygen sensors with a detection limit of 10 nmol kg-1 in combination with conventional hydrographic oxygen sensors along a cruise track transecting the Eastern South Pacific OMZ from South to North along the coast of Chile and Peru. Oxygen was below the detection limit throughout the ˜200 m thick OMZ core in most casts with STOX sensors. The only exception was an offshore location off Peru where oxygen was 10-50 nmol kg-1 in the core, likely as the result of a transient intrusion. Oxygen was also not detected in the OMZ core in further casts with conventional sensors, which had a detection limit of 90 nmol kg-1 after STOX-based zero calibration. Our measurements tighten the constraints on typical oxygen concentrations in the inner part of the OMZ by at least an order of magnitude relative to previous reports. Nitrite only accumulated when oxygen was depleted below 50 nmol kg-1, which indicates that nitrogen cycling is much more sensitive to oxygen than previously estimated. We argue that extreme oxygen depletion to low nanomalar or even picomolar concentrations is a normal condition in the South Pacific OMZ, and suggest that the OMZ core is in fact functionally anoxic over wide regions for extended periods. Our results further indicate that oxygen dynamics in the low nanomolar range play an important role in OMZ biogeochemistry.

A biphasic radiation survival response of mammalian cells to molecular oxygen

International Nuclear Information System (INIS)

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

1979-01-01

A study has been made of the responses of exponentially growing monolayers of Chinese hamster cells to γ-irradiation at low oxygen concentrations. Survival data showed progressively more sensitization with increasing oxygen concentration in the range 0.4 to 1.5 μM, but a constant amount of sensitization between 1.5 and 7.0 μM. Further sensitization was achieved at greater oxygen concentrations. The data imply that there are at least two components to the radiation inactivation of this cell line, and the full oxygen effect curve cannot be described in terms of a single competitive mechanism. (UK)

Relations between fatty acid synthesis, pyruvate concentration and cell concentration of suspensions of isolated rat hepatocytes

NARCIS (Netherlands)

Beynen, A.C.; Geelen, M.J.H.

1984-01-01

1. 1. The cell concentration of suspensions of isolated rat hepatocytes affects both the rate of pyruvate accumulation in the incubation medium and the rate of fatty acid synthesis. 2. 2. At low cell concentrations pyruvate accumulation is directly related to the cell concentration but levels off

Monitoring bioremediation of weathered diesel NAPL using oxygen depletion profiles

International Nuclear Information System (INIS)

Davis, G.B.; Johnston, C.D.; Patterson, B.M.; Barber, C.; Bennett, M.

1995-01-01

Semicontinuous logging of oxygen concentrations at multiple depths has been used to evaluate the progress of an in situ bioremediation trial at a site contaminated by weathered diesel nonaqueous-phase liquid (NAPL). The evaluation trial consisted of periodic addition of nutrients and aeration of a 100-m 2 trial plot. During the bioremediation trial, aeration was stopped periodically, and decreases in dissolved and gaseous oxygen concentrations were monitored using data loggers attached to in situ oxygen sensors placed at multiple depths above and within a thin NAPL-contaminated zone. Oxygen usage rate coefficients were determined by fitting zero- and first-order rate equations to the oxygen depletion curves. For nutrient-amended sites within the trial plot, estimates of oxygen usage rate coefficients were significantly higher than estimates from unamended sites. These rates also converted to NPL degradation rates, comparable to those achieved in previous studies, despite the high concentrations and weathered state of the NAPL at this test site

Internal-reference solid-electrolyte oxygen sensor

International Nuclear Information System (INIS)

Haaland, D.M.

1977-01-01

A new solid-electrolyte oxygen sensor has been developed that eliminates the conventional oxygen reference in previous solid-electrolyte oxygen sensor designs and is, therefore, ideally suited as an insertion device for remote oxygen monitoring applications. It is constructed with two cells of stabilized zirconia sealed into a small unit using a new high-temperature platinum-zirconia seal. One electrochemical cell monitors the ratio of oxygen partial pressures inside and outside the sensor while the other solid-electrolyte cell is used for quantitative electrochemical pumping of oxygen. The internal oxygen reference is generated by initially pumping all oxygen out of the known internal volume of the sensor and then quantitatively pumping oxygen back in until oxygen partial pressures are equal inside and out. This information is used with the ideal gas law to calculate oxygen partial pressures. Tests were conducted from 400 to 1000 0 C in mixtures of oxygen and nitrogen spanning approximately 0.2 to 21 percent oxygen concentration range. Sensors with sputtered platinum and porous platinum paste electrodes were compared

Microgradients of microbial oxygen consumption in a barley rhizosphere model system

DEFF Research Database (Denmark)

Højberg, Ole; Sorensen, J.

1993-01-01

A microelectrode technique was used to map the radial distribution of oxygen concentrations and oxygen consumption rates around single roots of 7- day-old barley seedlings. The seedlings were grown in gel-stabilized medium containing a nutrient solution, a soil extract, and an inert polymer. Oxygen...... consumption by microbial respiration in the rhizosphere (30 mm from the root) was determined by using Fick's laws of diffusion and an analytical approach with curve fitting to measured microprofiles of oxygen concentration. A marked increase of microbial respiration...... was observed in the inner 0- to 3-mm-thick, concentric zone around the root (rhizosphere). The volume-specific oxygen consumption rate (specific activity) was thus 30 to 60 times higher in the innermost 0 to 0.01 mm (rhizoplane) than in the bulk medium. The oxygen consumption rate in the root tissue...

Modeled long-term changes of DIN:DIP ratio in the Changjiang River in relation to Chl-α and DO concentrations in adjacent estuary

Science.gov (United States)

Wang, Jianing; Yan, Weijin; Chen, Nengwang; Li, Xinyan; Liu, Lusan

2015-12-01

In the past four decades (1970-2013), nitrogen and phosphorous inputs to the Changjiang River basin, mainly from human activities, have increased 3-fold and 306-fold, respectively. The riverine nutrient fluxes to the estuary have also grown exponentially. Dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorous (DIP) fluxes of the Changjiang River increased by 338% and 574% during 1970-2013 period, and red tides and benthic hypoxia have been observed in the outflow region of the Changjiang River in the East China Sea (ECS). We assumed that time series changes in the DIN:DIP ratio from the Changjiang River could have a significant impact on Chlorophyll-α (Chl-α) concentration in the surface sea water and dissolved oxygen (DO) concentration in the bottom sea water of the Changjiang estuary. Our study showed that the DIN:DIP ratio from the Changjiang River increased from 76 to 384 between 1970 and 1985, and decreased from 255 to 149 between 1986 and 2013. The observed Chl-α concentration increased by 146% from 1992 to 2010 in the Changjiang estuary, and was negatively related to the DIN:DIP ratio in 1992-2010. Bottom sea water DO concentration decreased by 24.6% during 1992-2010 and a "low oxygen zone" (122°∼123°E, 32°∼33°N) was observed during summer since 1999. The anthropogenically enhanced nutrient inputs dominated river DIN and DIP fluxes and influenced Chl-α concentrations as well as bottom DO concentrations in the estuary. Scenarios emphasizing global collaboration and proactive environmental problem-solving may result in reductions in the river nutrient exports and in Chl-α and DO concentration in the Changjiang estuary by 2050.

Diffusion coefficients of oxygen and hemoglobin as obtained simultaneously from photometric determination of the oxygenation of layers of hemoglobin solutions

NARCIS (Netherlands)

Spaan, J. A.; Kreuzer, F.; van Wely, F. K.

1980-01-01

The oxygenation of layers of deoxygenated hemoglobin solutions after a sudden exposure to a gas containing oxygen at a partial pressure P1 has been studied by a photometric method. Layer thicknesses varied between 50 and 250 micron, hemoglobin concentrations between 0.1 and 0.34kg/l, and oxygen

Biological phosphorus and nitrogen removal in sequencing batch reactors: effects of cycle length, dissolved oxygen concentration and influent particulate matter.

Science.gov (United States)

Ginige, Maneesha P; Kayaalp, Ahmet S; Cheng, Ka Yu; Wylie, Jason; Kaksonen, Anna H

2013-01-01

Removal of phosphorus (P) and nitrogen (N) from municipal wastewaters is required to mitigate eutrophication of receiving water bodies. While most treatment plants achieve good N removal using influent carbon (C), the use of influent C to facilitate enhanced biological phosphorus removal (EBPR) is poorly explored. A number of operational parameters can facilitate optimum use of influent C and this study investigated the effects of cycle length, dissolved oxygen (DO) concentration during aerobic period and influent solids on biological P and N removal in sequencing batch reactors (SRBs) using municipal wastewaters. Increasing cycle length from 3 to 6 h increased P removal efficiency, which was attributed to larger portion of N being removed via nitrite pathway and more biodegradable organic C becoming available for EBPR. Further increasing cycle length from 6 to 8 h decreased P removal efficiencies as the demand for biodegradable organic C for denitrification increased as a result of complete nitrification. Decreasing DO concentration in the aerobic period from 2 to 0.8 mg L(-1) increased P removal efficiency but decreased nitrification rates possibly due to oxygen limitation. Further, sedimented wastewater was proved to be a better influent stream than non-sedimented wastewater possibility due to the detrimental effect of particulate matter on biological nutrient removal.

Single-cell measurement of red blood cell oxygen affinity.

Science.gov (United States)

Di Caprio, Giuseppe; Stokes, Chris; Higgins, John M; Schonbrun, Ethan

2015-08-11

Oxygen is transported throughout the body by hemoglobin (Hb) in red blood cells (RBCs). Although the oxygen affinity of blood is well-understood and routinely assessed in patients by pulse oximetry, variability at the single-cell level has not been previously measured. In contrast, single-cell measurements of RBC volume and Hb concentration are taken millions of times per day by clinical hematology analyzers, and they are important factors in determining the health of the hematologic system. To better understand the variability and determinants of oxygen affinity on a cellular level, we have developed a system that quantifies the oxygen saturation, cell volume, and Hb concentration for individual RBCs in high throughput. We find that the variability in single-cell saturation peaks at an oxygen partial pressure of 2.9%, which corresponds to the maximum slope of the oxygen-Hb dissociation curve. In addition, single-cell oxygen affinity is positively correlated with Hb concentration but independent of osmolarity, which suggests variation in the Hb to 2,3-diphosphoglycerate (2-3 DPG) ratio on a cellular level. By quantifying the functional behavior of a cellular population, our system adds a dimension to blood cell analysis and other measurements of single-cell variability.

Intraoperative transfusion threshold and tissue oxygenation

DEFF Research Database (Denmark)

Nielsen, K; Dahl, B; Johansson, P I

2012-01-01

Transfusion with allogeneic red blood cells (RBCs) may be needed to maintain oxygen delivery during major surgery, but the appropriate haemoglobin (Hb) concentration threshold has not been well established. We hypothesised that a higher level of Hb would be associated with improved subcutaneous...... oxygen tension during major spinal surgery....

Fate of leaf litter deposits and impacts on oxygen availability in bank filtration column studies.

Science.gov (United States)

Bayarsaikhan, Uranchimeg; Filter, Josefine; Gernert, Ulrich; Jekel, Martin; Ruhl, Aki Sebastian

2018-07-01

Degradation of particulate organic carbon (POC) such as leaf litter might deplete dissolved oxygen within the upper layers of bank filtration, an efficient and robust barrier for pathogens and for various organic micro-pollutants (OMP) in water supply systems worldwide. The degradation of OMP during bank filtration depends on the redox conditions. The present study aimed at identifying the impacts and fates of different local leaves on the oxygen consumption and the possible biological degradation of indicator OMP. Oxygen concentrations initially decreased within the columns from around 8 mg/L in the influent to low concentrations indicating extensive consumption within a short travel distance. Still a substantial oxygen consumption was observed after 250 days. OMP concentrations were not significantly affected by the microbial processes. A layer of calcium carbonate crystallites was observed on the POC layer. Some leaf fragments appeared to be persistant towards degradation and the carbon content relative to nitrogen and sulfur contents decreased within 250 days. The results demonstrate that trees at bank filtration sites might have a strong long-term impact on the subsurface redox conditions. Copyright © 2018 Elsevier Inc. All rights reserved.

Evidence of sub-10 nm aluminum-oxygen precipitates in silicon

International Nuclear Information System (INIS)

Moutanabbir, Oussama; Isheim, Dieter; Mao, Zugang; Seidman, David N

2016-01-01

In this research, ultraviolet laser-assisted atom-probe tomography (APT) was utilized to investigate precisely the behavior at the atomistic level of aluminum impurities in ultrathin epitaxial silicon layers. Aluminum atoms were incorporated in situ during the growth process. The measured average aluminum concentration in the grown layers exceeds by several orders of magnitude the equilibrium bulk solubility. Three-dimensional atom-by-atom mapping demonstrates that aluminum atoms precipitate in the silicon matrix and form nanoscopic precipitates with lateral dimensions in the 1.3 to 6.2 nm range. These precipitates were found to form only in the presence of oxygen impurity atoms, thus providing clear evidence of the long-hypothesized role of oxygen and aluminum-oxygen complexes in facilitating the precipitation of aluminum in a silicon lattice. The measured average aluminum and oxygen concentrations in the precipitates are ∼10 ± 0.5 at.% and ∼4.4 ± 0.5 at.%, respectively. This synergistic interaction is supported by first-principles calculations of the binding energies of aluminum-oxygen dimers in silicon. The calculations demonstrate that there is a strong binding between aluminum and oxygen atoms, with Al-O-Al and O-Al-Al as the energetically favorable sequences corresponding to precipitates in which the concentration of aluminum is twice as large as the oxygen concentration in agreement with APT data. (paper)

Oxygen-dependent growth of the obligate anaerobe Desulfovibrio vulgaris Hildenborough.

OpenAIRE

Johnson, M S; Zhulin, I B; Gapuzan, M E; Taylor, B L

1997-01-01

Desulfovibrio vulgaris Hildenborough, a sulfate-reducing bacterium classified as an obligate anaerobe, swam to a preferred oxygen concentration of 0.02 to 0.04% (0.24 to 0.48 microM), a level which also supported growth. Oxygen concentrations of 0.08% and higher arrested growth. We propose that in zones of transition from an oxic to an anoxic environment, D. vulgaris protects anoxic microenvironments from intrusion of oxygen.

The role of nitrogen in the formation of oxygen-related thermal donors in silicon

International Nuclear Information System (INIS)

Griffin, J.A.; Hartung, J.; Weber, J.

1989-01-01

Nitrogen doped silicon is investigated by Photothermal Ionisation Spectroscopy (PTIS) and Infrared Absorption (IR). The Shallow Thermal Donors (STD) are observed in this nitrogen doped Cz-silicon as well as the deeper Thermal Donors (TD). The Thermal Donor Growth in nitrogen doped material is reduced in comparison to nominally undoped oxygen-rich silicon. The half-widths of the spectral lines arising from the STD-transitions are observed to be dependent on the nitrogen concentration. The results suggest only a catalytic role of N in the STD-growth. (author) 13 refs., 3 figs., 1 tab

Oxygen diffusion in monazite

Science.gov (United States)

Cherniak, D. J.; Zhang, X. Y.; Nakamura, M.; Watson, E. B.

2004-09-01

We report measurements of oxygen diffusion in natural monazites under both dry, 1-atm conditions and hydrothermal conditions. For dry experiments, 18O-enriched CePO4 powder and monazite crystals were sealed in Ag-Pd capsules with a solid buffer (to buffer at NNO) and annealed in 1-atm furnaces. Hydrothermal runs were conducted in cold-seal pressure vessels, where monazite grains were encapsulated with 18O-enriched water. Following the diffusion anneals, oxygen concentration profiles were measured with Nuclear Reaction Analysis (NRA) using the reaction 18O(p,α)15N. Over the temperature range 850-1100 °C, the Arrhenius relation determined for dry diffusion experiments on monazite is given by: Under wet conditions at 100 MPa water pressure, over the temperature range 700-880 °C, oxygen diffusion can be described by the Arrhenius relationship: Oxygen diffusion under hydrothermal conditions has a significantly lower activation energy for diffusion than under dry conditions, as has been found the case for many other minerals, both silicate and nonsilicate. Given these differences in activation energies, the differences between dry and wet diffusion rates increase with lower temperatures; for example, at 600 °C, dry diffusion will be more than 4 orders of magnitude slower than diffusion under hydrothermal conditions. These disparate diffusivities will result in pronounced differences in the degree of retentivity of oxygen isotope signatures. For instance, under dry conditions (presumably rare in the crust) and high lower-crustal temperatures (∼800 °C), monazite cores of 70-μm radii will preserve O isotope ratios for about 500,000 years; by comparison, they would be retained at this temperature under wet conditions for about 15,000 years.

Fast Oxidation Processes in a Naturally Reduced Aquifer Zone Caused by Dissolved Oxygen

Science.gov (United States)

Davis, J. A.; Jemison, N. E.; Williams, K. H.; Hobson, C.; Bush, R. P.

2014-12-01

The occurrence of naturally reduced zones is quite common in alluvial aquifers in the western U.S.A. due to the burial of woody debris in flood plains. The naturally reduced zones are heterogeneously dispersed in such aquifers and are characterized by high concentrations of organic carbon and reduced phases, including iron sulfides and reduced forms of metals, including uranium(IV). The persistence of high concentrations of dissolved uranium(VI) at uranium-contaminated aquifers on the Colorado Plateau has been attributed to slow oxidation of insoluble uranium(IV) mineral phases that are found in association with these natural reducing zones, although there is little understanding of the relative importance of various potential oxidants. Three field experiments were conducted within an alluvial aquifer adjacent to the Colorado River near Rifle, CO wherein groundwater associated with naturally reduced zones was pumped into a gas-impermeable tank, mixed with a conservative tracer (Br-), bubbled with a gas phase composed of 97% O2 and 3% CO2, and then returned to the subsurface in the same well from which it was withdrawn. Within minutes of re-injection of the oxygenated groundwater, dissolved uranium(VI) concentrations increased from less than 1 μM to greater than 2.5 μM, demonstrating that oxygen can be an important oxidant for uranium in these field systems if supplied to the naturally reduced zones. Small concentrations of nitrate were also observed in the previously nitrate-free groundwater, and Fe(II) decreased to the detection limit. These results contrast with other laboratory and field results in which oxygen was introduced to systems containing high concentrations of mackinawite (FeS) rather than the more crystalline iron sulfides found in aged, naturally reduced zones. The flux of oxygen to the naturally reduced zones in the alluvial aquifers occurs mainly through interactions between groundwater and gas phases at the water table, and seasonal variations

Acute supramaximal exercise increases the brain oxygenation in relation to cognitive workload

Directory of Open Access Journals (Sweden)

Cem Seref Bediz

2016-04-01

Full Text Available Single bout of exercise can improve the performance on cognitive tasks. However, cognitive responses may be controversial due to different type, intensity, and duration of exercise. In addition, the mechanism of the effect of acute exercise on brain is still unclear. This study was aimed to investigate the effects of supramaximal exercise on cognitive tasks by means of brain oxygenation monitoring. The brain oxygenation of Prefrontal cortex (PFC was measured on 35 healthy male volunteers via functional Near Infrared Spectroscopy (fNIRS system. Subjects performed 2-Back test before and after the supramaximal exercise (Wingate Anaerobic Test lasting 30-s on cycle ergometer. The PFC oxygenation change evaluation revealed that PFC oxygenation rise during post-exercise 2-Back task was considerably higher than those in pre-exercise 2-Back task. In order to describe the relationship between oxygenation change and exercise performance, subjects were divided into two groups as high performers (HP and low performers (LP according to their peak power values (PP obtained from the supramaximal test. The oxy-hemoglobin (oxy-Hb values were compared between pre- and post-exercise conditions within subjects and also between subjects according to peak power. When performers were compared, in the HP group, the oxy-Hb values in post-exercise 2-Back test were significantly higher than those in pre-exercise 2-Back test. HP had significantly higher post-exercise oxy-Hb change (Δ than those of LP. In addition, peak power values of the total group were significantly correlated with Δoxy-Hb. The key findings of the present study revealed that acute supramaximal exercise has an impact on the brain oxygenation during a cognitive task. Also, the higher the anaerobic PP describes the larger the oxy-Hb response in post-exercise cognitive task. The current study also demonstrated a significant correlation between peak power (exercise load and post-exercise hemodynamic

Effects of Acute Bleeding Followed by Hydroxyethyl Starch 130/0.4 or a Crystalloid on Propofol Concentrations, Cerebral Oxygenation, and Electroencephalographic and Haemodynamic Variables in Pigs

Directory of Open Access Journals (Sweden)

Aura Silva

2014-01-01

Full Text Available Bleeding changes the haemodynamics, compromising organ perfusion. In this study, the effects of bleeding followed by replacement with hydroxyethyl starch 130/0.4 (HES or lactated Ringer’s (LR on cerebral oxygenation and electroencephalogram-derived parameters were investigated. Twelve young pigs under propofol-remifentanil anaesthesia were bled 30 mL/kg and, after a 20-minute waiting period, volume replacement was performed with HES (GHES; N=6 or LR (GRL; N=6. Bleeding caused a decrease of more than 50% in mean arterial pressure (P<0.01 and a decrease in cerebral oximetry (P=0.039, bispectral index, and electroencephalogram total power (P=0.04 and P<0.01, resp., while propofol plasma concentrations increased (P<0.01. Both solutions restored the haemodynamics and cerebral oxygenation similarly and were accompanied by an increase in electroencephalogram total power. No differences between groups were found. However, one hour after the end of the volume replacement, the cardiac output (P=0.03 and the cerebral oxygenation (P=0.008 decreased in the GLR and were significantly lower than in GHES (P=0.02. Volume replacement with HES 130/0.4 was capable of maintaining the cardiac output and cerebral oxygenation during a longer period than LR and caused a decrease in the propofol plasma concentrations.

Oxygen status during haemodialysis. The Cord-Group

DEFF Research Database (Denmark)

Nielsen, A L; Jensen, H Æ; Hegbrant, J

1995-01-01

Hypoxia during haemodialysis, mainly acetate, has been reported several times. In our study we have monitored oxygen status during 258 bicarbonate haemodialyses. A significant drop below 80 mmHg in mean oxygen tension occurred. Mean oxygen saturation reflected this drop but did not reach levels...... below 90%. The mean oxygen concentration was on the whole critical low, though slightly increasing during each haemodialysis session due to ultrafiltration. It is concluded that both hypoxia and hypoxaemia do occur during bicarbonate haemodialysis. To a group of patients generally having limited cardiac...... reserves, a poor oxygen status is a potentially serious complication to haemodialysis. Monitoring oxygen status is thus advisable....

Investigation of Molecular Structure and Thermal Properties of Thermo-Oxidative Aged SBS in Blends and Their Relations.

Science.gov (United States)

Xu, Xiong; Yu, Jianying; Xue, Lihui; Zhang, Canlin; Zha, Yagang; Gu, Yi

2017-07-07

Tri-block copolymer styrene-butadiene (SBS) is extensively applied in bituminous highway construction due to its high elasticity and excellent weather resistance. With the extension of time, tri-block structural SBS automatically degrades into bi-block structural SB- with some terminal oxygen-containing groups under the comprehensive effects of light, heat, oxygen, etc. In this paper, the effects of aging temperature, aging time and oxygen concentration on the molecular structure of thermo-oxidative aged SBS were mainly investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), and the correlation between oxygen-containing groups and thermal properties (TG-DTG) was further discussed. The FTIR and XPS results show that rapid decomposition of SBS will occur with increments of aging temperature, aging time and oxygen concentration, and a large number of oxygen-containing groups such as -OH, C=O, -COOH, etc. will be formed during thermo-oxidative aging. In short-term aging, changes in aging temperature and oxygen concentration have a significant impact on the structural damage of SBS. However, in long-term aging, it has no further effect on the molecular structure of SBS or on increasing oxygen concentration. The TG and DTG results indicate that the concentration of substances with low molecular weight gradually increases with the improvement of the degree of aging of the SBS, while the initial decomposition rate increases at the beginning of thermal weightlessness and the decomposition rate slows down in comparison with neat SBS. From the relation between the XPS and TG results, it can be seen that the initial thermal stability of SBS rapidly reduces as the relative concentration of the oxygen-containing groups accumulates around 3%, while the maximum decomposition temperature slowly decreases when the relative concentration of the oxygen-containing groups is more than 3%, due to the difficult damage to strong bonds

CLIMATE CHANGE. Long-term climate forcing by atmospheric oxygen concentrations.

Science.gov (United States)

Poulsen, Christopher J; Tabor, Clay; White, Joseph D

2015-06-12

The percentage of oxygen in Earth's atmosphere varied between 10% and 35% throughout the Phanerozoic. These changes have been linked to the evolution, radiation, and size of animals but have not been considered to affect climate. We conducted simulations showing that modulation of the partial pressure of oxygen (pO2), as a result of its contribution to atmospheric mass and density, influences the optical depth of the atmosphere. Under low pO2 and a reduced-density atmosphere, shortwave scattering by air molecules and clouds is less frequent, leading to a substantial increase in surface shortwave forcing. Through feedbacks involving latent heat fluxes to the atmosphere and marine stratus clouds, surface shortwave forcing drives increases in atmospheric water vapor and global precipitation, enhances greenhouse forcing, and raises global surface temperature. Our results implicate pO2 as an important factor in climate forcing throughout geologic time. Copyright © 2015, American Association for the Advancement of Science.

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

Science.gov (United States)

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.

[Differences and sources of CO2 concentration, carbon and oxygen stable isotope composition between inside and outside of a green space system and influencing factors in an urban area].

Science.gov (United States)

Sun, Shou-jia; Meng, Ping; Zhang, Jin-song; Shu, Jian-hua; Zheng, Ning

2015-10-01

The off-axis integrated cavity output spectroscopy technique was used to measure air CO2 concentration, stable carbon (δ13C) and oxygen (δ18C) isotope ratios on the Fourth Ring Road (FRR) and in the green space system of Beijing Institute of Landscape Architecture (BILA) in summer and winter seasons. The variations of CO2 concentration, δ13C value, δ18C value and the differences of them between the FRR and the BILA, which were correlated with traffic volume and meteorological factors, were analyzed at half-hour timescale. The results showed that traffic volume on the FRR was large both in summer and winter with obvious morning and evening rush hours, and more than 150 thousands vehicles were observed everyday during the observation periods. Diurnal variation of the CO2 concentration showed a two-peak curve both on the FRR and in the green space system of the BILA. In contrast, diurnal variation of δ13C value was a two-trough curve while diurnal variation of δ18O value was a single-trough curve. The differences of CO2 concentration, δ13C value and δ18O value between the FRR and the green space system of BILA in summer were greater than those in winter. The carbon isotope partitioning results showed that in summer vehicle exhaust contributed 64.9% to total atmospheric CO2 of the FRR during measurement time, while heterotrophic respiration contributed 56.3% to total atmospheric CO2 of the green space system in BILA. However, in winter atmospheric CO2 from both the FRR and green space system mostly came from vehicle exhaust. Stepwise regression analysis indicated that differences of CO2 concentration between the FRR and green space system were significantly related to vehicle volume and solar radiation at half-hour timescale, while solar radiation and relative humidity were the main meteorological factors causing δ13 and δ18O differences between the FRR and green space system. Plants in the green space system strongly assimilated CO2 from fossil fuel burning

Oxygen diffusion through soil covers on sulphidic mine tailings

International Nuclear Information System (INIS)

Yanful, E.K.

1993-01-01

Engineered soil covers are being evaluated under Canada's Mine Environment Neutral Drainage (MEND) program for their effectiveness in preventing and controlling acid generation in sulfidic mill tailings. A critical parameter for predicting the performance of these covers is the diffusion coefficient of gaseous oxygen in the cover materials. Laboratory experiments conducted to determine the effective diffusion coefficient of a candidate cover material, a glacial till from an active mine site, are described. The diffusion coefficient is determined by fitting a semianalytic solution of the one-dimensional, transient diffusion equation to experimental gaseous oxygen concentration versus time graphs. Effective diffusion coefficients determined at high water saturations (85%--95%) were of the order of 8 x 10 -8 m 2 /s. The diffusion coefficients decreased with increase in water saturation as a result of the low diffusivity of gaseous oxygen in water relative to that in air and the low solubility of oxygen in water. Placement of soil covers in high saturation conditions would ensure that the flux of oxygen into tailings underneath such covers is low, resulting in low acid flux. This is confirmed by combined laboratory, field, and modeling studies

Determination of oxygen in liquid sodium

International Nuclear Information System (INIS)

Torre, M. de la; Lapena, J.; Galindo, F.; Couchoud, M.; Celis, B. de; Lopez-Araquistain, J.L.

1976-01-01

The behaviour is analysed of a device for 'in-line' sampling and vacuum distillation. With this procedure 95 results were obtained for the solubility of oxygen in liquid sodium at temperatures between 125 0 and 300 0 C. The correlation between the concentration of oxygen in a saturation state and the corresponding temperature is represented by: 1g C = 6,17 - 2398/T, where C expressed ppm of oxygen by weight and T is the saturation temperature in 0 K. Reference is also made to the first results obtained with the electrochemical oxygen meter and the system for taking and recording data. (author)

Portable Cathode-Air-Vapor-Feed Electrochemical Medical Oxygen Concentrator, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Future space exploration missions present significant new challenges to crew health care capabilities, particularly in the efficient utilization of on-board oxygen...

Net community production from autonomous oxygen observations in the Sargasso Sea

Science.gov (United States)

Feen, M.; Estapa, M. L.

2016-02-01

Optical sensors on autonomous floats provide high-resolution profiles of oxygen concentration over time. Improved spatiotemporal resolution in our measurements of oxygen will allow for better estimates of net community production and a greater understanding of the biological pump. Two autonomous profiling floats (NAVIS BGCi, Sea-Bird) equipped with SBE-63 optodes to measure dissolved oxygen were deployed in the Sargasso Sea on a series of five Bermuda Atlantic Time-series Study (BATS) cruises from July 2013 to April 2014. In situ calibration of the oxygen sensors to Winkler titration bottle samples at BATS did not show systematic drift in the oxygen sensors over time. Calibrations were applied to determine oxygen concentrations in profiles collected in the Sargasso Sea at 1.5 to 2.5 day intervals over a year. Oxygen concentrations were used to quantify sub-mixed layer net community production. Changes in production rates from this study were compared with upper water column biology and particle flux measurements obtained independently from optical sensors on the profiling floats, allowing us to examine processes controlling carbon export into the deep ocean.

The neurovascular relation in oxygen-induced retinopathy.

Science.gov (United States)

Akula, James D; Mocko, Julie A; Benador, Ilan Y; Hansen, Ronald M; Favazza, Tara L; Vyhovsky, Tanya C; Fulton, Anne B

2008-01-01

Longitudinal studies in rat models of retinopathy of prematurity (ROP) have demonstrated that abnormalities of retinal vasculature and function change hand-in-hand. In the developing retina, vascular and neural structures are under cooperative molecular control. In this study of rats with oxygen-induced retinopathy (OIR) models of ROP, mRNA expression of vascular endothelial growth factor (VEGF), semaphorin (Sema), and their neuropilin receptor (NRP) were examined during the course of retinopathy to evaluate their roles in the observed neurovascular congruency. Oxygen exposures designed to induce retinopathy were delivered to Sprague-Dawley rat pups (n=36) from postnatal day (P) 0 to P14 or from P7 to P14. Room-air-reared controls (n=18) were also studied. Sensitivities of the rod photoreceptors (S(rod)) and the postreceptor cells (Sm) were derived from electroretinographic (ERG) records. Arteriolar tortuosity, T(A), was derived from digital fundus images using Retinal Image multi-Scale Analysis (RISA) image analysis software. mRNA expression of VEGF(164), semaphorin IIIA (Sema3A), and neuropilin-1 (NRP-1) was evaluated by RT-PCR of retinal extracts. Tests were performed at P15-P16, P18-P19, and P25-P26. Relations among ERG, RISA, and PCR parameters were evaluated using linear regression on log transformed data. Sm was low and T(A) was high at young ages, then both resolved by P25-P26. VEGF(164) and Sema3A mRNA expression were also elevated early and decreased with age. Low Sm was significantly associated with high VEGF(164) and Sema3A expression. Low S(rod) was also significantly associated with high VEGF(164). S(rod) and Sm were both correlated with T(A). NRP-1 expression was little affected by OIR. The postreceptor retina appears to mediate the vascular abnormalities that characterize OIR. Because of the relationships revealed by these data, early treatment that targets the neural retina may mitigate the effects of ROP.

Expression of death-related genes and reactive oxygen species production in Skeletonema tropicum upon exposure to the polyunsaturated aldehyde octadienal

Directory of Open Access Journals (Sweden)

Alessandra A. Gallina

2015-11-01

Full Text Available The effects of 4E/Z-octadienal (OCTA on ScDSP-1 and ScDSP-2 gene expression and reactive oxygen species (ROS production were investigated in the marine diatom Skeletonema tropicum (formerly costatum using qRTPCR and flow cytometry. ScDSP-1 and ScDSP-2 genes have been previously shown to be involved in cell death in ageing cells and in response to photosynthetic stress. OCTA induced a differential, concentration-dependent DSP gene expression associated to ROS production, 821.6 and 97.7 folds higher for ScDSP-1 and ScDSP-2, respectively. Among the concentrations tested, only 8 μM OCTA, which caused a reduction of 50% in cell concentrations at 24 h, was able to elicit an expression pattern consistent with a signalling role. Interestingly, only intermediate levels of reactive oxygen species (ROS (i.e., 1.5±0.1 increase were observed to be elicited by such concentration. These results suggest that ROS are key components of the molecular cascade triggered by polyunsaturated aldehydes (PUA and leading to cell death. This could have implications for bloom final stages at sea, where PUA may act as effectors of diatom population dynamics through ROS acting as modulators.

Uptake rate of cationic mitochondrial inhibitor MKT-077 determines cellular oxygen consumption change in carcinoma cells.

Directory of Open Access Journals (Sweden)

John L Chunta

Full Text Available OBJECTIVE: Since tumor radiation response is oxygen-dependent, radiosensitivity can be enhanced by increasing tumor oxygenation. Theoretically, inhibiting cellular oxygen consumption is the most efficient way to increase oxygen levels. The cationic, rhodacyanine dye-analog MKT-077 inhibits mitochondrial respiration and could be an effective metabolic inhibitor. However, the relationship between cellular MKT-077 uptake and metabolic inhibition is unknown. We hypothesized that rat and human mammary carcinoma cells would take up MKT-077, causing a decrease in oxygen metabolism related to drug uptake. METHODS: R3230Ac rat breast adenocarcinoma cells were exposed to MKT-077. Cellular MKT-077 concentration was quantified using spectroscopy, and oxygen consumption was measured using polarographic electrodes. MKT-077 uptake kinetics were modeled by accounting for uptake due to both the concentration and potential gradients across the plasma and mitochondrial membranes. These kinetic parameters were used to model the relationship between MKT-077 uptake and metabolic inhibition. MKT-077-induced changes in oxygen consumption were also characterized in MDA-MB231 human breast carcinoma cells. RESULTS: Cells took up MKT-077 with a time constant of ∼1 hr, and modeling showed that over 90% of intracellular MKT-077 was bound or sequestered, likely by the mitochondria. The uptake resulted in a rapid decrease in oxygen consumption, with a time constant of ∼30 minutes. Surprisingly the change in oxygen consumption was proportional to uptake rate, not cellular concentration. MKT-077 proved a potent metabolic inhibitor, with dose-dependent decreases of 45-73% (p = 0.003. CONCLUSIONS: MKT-077 caused an uptake rate-dependent decrease in cellular metabolism, suggesting potential efficacy for increasing tumor oxygen levels and radiosensitivity in vivo.

Singlet Oxygen and Free Radical Reactions of Retinoids and Carotenoids—A Review

Science.gov (United States)

Truscott, T. George

2018-01-01

We report on studies of reactions of singlet oxygen with carotenoids and retinoids and a range of free radical studies on carotenoids and retinoids with emphasis on recent work, dietary carotenoids and the role of oxygen in biological processes. Many previous reviews are cited and updated together with new data not previously reviewed. The review does not deal with computational studies but the emphasis is on laboratory-based results. We contrast the ease of study of both singlet oxygen and polyene radical cations compared to neutral radicals. Of particular interest is the switch from anti- to pro-oxidant behavior of a carotenoid with change of oxygen concentration: results for lycopene in a cellular model system show total protection of the human cells studied at zero oxygen concentration, but zero protection at 100% oxygen concentration. PMID:29301252

Implementing oxygen control in chip-based cell and tissue culture systems.

Science.gov (United States)

Oomen, Pieter E; Skolimowski, Maciej D; Verpoorte, Elisabeth

2016-09-21

Oxygen is essential in the energy metabolism of cells, as well as being an important regulatory parameter influencing cell differentiation and function. Interest in precise oxygen control for in vitro cultures of tissues and cells continues to grow, especially with the emergence of the organ-on-a-chip and the desire to emulate in vivo conditions. This was recently discussed in this journal in a Critical Review by Brennan et al. (Lab Chip (2014). DOI: ). Microfluidics can be used to introduce flow to facilitate nutrient supply to and waste removal from in vitro culture systems. Well-defined oxygen gradients can also be established. However, cells can quickly alter the oxygen balance in their vicinity. In this Tutorial Review, we expand on the Brennan paper to focus on the implementation of oxygen analysis in these systems to achieve continuous monitoring. Both electrochemical and optical approaches for the integration of oxygen monitoring in microfluidic tissue and cell culture systems will be discussed. Differences in oxygen requirements from one organ to the next are a challenging problem, as oxygen delivery is limited by its uptake into medium. Hence, we discuss the factors determining oxygen concentrations in solutions and consider the possible use of artificial oxygen carriers to increase dissolved oxygen concentrations. The selection of device material for applications requiring precise oxygen control is discussed in detail, focusing on oxygen permeability. Lastly, a variety of devices is presented, showing the diversity of approaches that can be employed to control and monitor oxygen concentrations in in vitro experiments.

Phenotypic plasticity in blood–oxygen transport in highland and lowland deer mice

Science.gov (United States)

Tufts, Danielle M.; Revsbech, Inge G.; Cheviron, Zachary A.; Weber, Roy E.; Fago, Angela; Storz, Jay F.

2013-01-01

SUMMARY In vertebrates living at high altitude, arterial hypoxemia may be ameliorated by reversible changes in the oxygen-carrying capacity of the blood (regulated by erythropoiesis) and/or changes in blood–oxygen affinity (regulated by allosteric effectors of hemoglobin function). These hematological traits often differ between taxa that are native to different elevational zones, but it is often unknown whether the observed physiological differences reflect fixed, genetically based differences or environmentally induced acclimatization responses (phenotypic plasticity). Here, we report measurements of hematological traits related to blood–O2 transport in populations of deer mice (Peromyscus maniculatus) that are native to high- and low-altitude environments. We conducted a common-garden breeding experiment to assess whether altitude-related physiological differences were attributable to developmental plasticity and/or physiological plasticity during adulthood. Under conditions prevailing in their native habitats, high-altitude deer mice from the Rocky Mountains exhibited a number of pronounced hematological differences relative to low-altitude conspecifics from the Great Plains: higher hemoglobin concentrations, higher hematocrits, higher erythrocytic concentrations of 2,3-diphosphoglycerate (an allosteric regulator of hemoglobin–oxygen affinity), lower mean corpuscular hemoglobin concentrations and smaller red blood cells. However, these differences disappeared after 6 weeks of acclimation to normoxia at low altitude. The measured traits were also indistinguishable between the F1 progeny of highland and lowland mice, indicating that there were no persistent differences in phenotype that could be attributed to developmental plasticity. These results indicate that the naturally occurring hematological differences between highland and lowland mice are environmentally induced and are largely attributable to physiological plasticity during adulthood. PMID

Studies on the rheology and oxygen mass transfer in the clavulanic acid production by Streptomyces clavuligerus

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E. R. Gouveia

2000-12-01

Full Text Available In the present work rheological characteristics and volumetric oxygen transfer coefficient (kLa were investigated during batch cultivations of Streptomyces clavuligerus NRRL 3585 for production of clavulanic acid. The experimental rheological data could be adequately described in terms of the power law model and logistic equation. Significant changes in the rheological parameters consistency index (K and flow behavior index (n were observed with the fermentation evolution. Interesting correlations between the consistency index (K/biomass concentration (C X and the flow behavior index (n/biomass concentration were proposed. Volumetric oxygen mass transfer coefficient (kLa was determined by the gas balance method. Classical correlation relating the volumetric oxygen mass transfer coefficient to the operating conditions, physical and to transport properties, including apparent viscosity (muap, could be applied to the experimental results.

The role of oxygen in the uptake of deuterium in lithiated graphite

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Taylor, C. N.; Luitjohan, K. E. [School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Dadras, J. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37998 (United States); Allain, J. P. [School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, West Lafayette, Indiana 47907 (United States); Krstic, P. S. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37998 (United States); Joint Institute of Computational Sciences, University of Tennessee, Knoxville, Tennessee 37998 (United States); Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Skinner, C. H. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2013-12-14

We investigate the mechanism of deuterium retention by lithiated graphite and its relationship to the oxygen concentration through surface sensitive experiments and atomistic simulations. Deposition of lithium on graphite yielded 5%–8% oxygen surface concentration and when subsequently irradiated with D ions at energies between 500 and 1000 eV/amu and fluences over 10{sup 16} cm{sup −2} the oxygen concentration rose to between 25% and 40%. These enhanced oxygen levels were reached in a few seconds compared to about 300 h when the lithiated graphite was allowed to adsorb oxygen from the ambient environment under equilibrium conditions. Irradiating graphite without lithium deposition, however, resulted in complete removal of oxygen to levels below the detection limit of XPS (e.g., <1%). These findings confirm the predictions of atomistic simulations, which had concluded that oxygen was the primary component for the enhanced hydrogen retention chemistry on the lithiated graphite surface.

Effect of hypolimnetic oxygenation on oxygen depletion rates in two water-supply reservoirs.

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Gantzer, Paul A; Bryant, Lee D; Little, John C

2009-04-01

Oxygenation systems, such as bubble-plume diffusers, are used to improve water quality by replenishing dissolved oxygen (DO) in the hypolimnia of water-supply reservoirs. The diffusers induce circulation and mixing, which helps distribute DO throughout the hypolimnion. Mixing, however, has also been observed to increase hypolimnetic oxygen demand (HOD) during system operation, thus accelerating oxygen depletion. Two water-supply reservoirs (Spring Hollow Reservoir (SHR) and Carvins Cove Reservoir (CCR)) that employ linear bubble-plume diffusers were studied to quantify diffuser effects on HOD. A recently validated plume model was used to predict oxygen addition rates. The results were used together with observed oxygen accumulation rates to evaluate HOD over a wide range of applied gas flow rates. Plume-induced mixing correlated well with applied gas flow rate and was observed to increase HOD. Linear relationships between applied gas flow rate and HOD were found for both SHR and CCR. HOD was also observed to be independent of bulk hypolimnion oxygen concentration, indicating that HOD is controlled by induced mixing. Despite transient increases in HOD, oxygenation caused an overall decrease in background HOD, as well as a decrease in induced HOD during diffuser operation, over several years. This suggests that the residual or background oxygen demand decreases from one year to the next. Despite diffuser-induced increases in HOD, hypolimnetic oxygenation remains a viable method for replenishing DO in thermally-stratified water-supply reservoirs such as SHR and CCR.

Chapter A7. Section 7.0. Five-Day Biochemical Oxygen Demand

Science.gov (United States)

Delzer, Gregory C.; McKenzie, Stuart W.

1999-01-01

The presence of a sufficient concentration of dissolved oxygen is critical to maintaining the aquatic life and aesthetic quality of streams and lakes. Determinng how organic matter affects the concentration of dissolved oxygen (DO) in a stream or lake is integral to water-quality management. The decay of organic matter in water is measured as biochemical or chemical oxygen demand. This report describes the field protocols used by U.S. Geological Survey (USGS) personnel to determine the five-day test for biochemical oxygen demand.

The reactions of oxygen and hydrogen with liquid sodium

International Nuclear Information System (INIS)

Ullmann, H.

1981-01-01

Results so far available as to the reactions and chemical equilibrium of oxygen and hydrogen with liquid sodium have been analyzed critically. The enthalpy values of the reactions have been discussed and supplemented on the basis of corresponding BORN-HABER cycles. The concentration and temperature functions of the hydrogen equilibrium pressure were deduced from experimental results. In relation to the solubility data the solid phases coexisting with liquid sodium in the ternary system Na-O-H have been discussed. The reaction of oxygen with hydrogen in diluted solution in liquid sodium has been investigated in more detail. Interaction coefficients, and the temperature functions of the free energy of formation and the equilibrium constant have been determined. (orig.)

[Recent technical advances in portable oxygen delivery systems].

Science.gov (United States)

Machida, K; Kawabe, Y; Mori, M; Haga, T

1992-08-01

According to a Japanese national survey (June 30, 1990), the number of patients receiving home oxygen therapy (HOT) has been greater than 18,000 since March 1985, when HOT was first covered by health insurance. The oxygen concentrator, especially the molecular sieve type, is the most common method of delivery (more than 90%). In April 1988, the portable oxygen cylinder was acknowledged by health insurance, and the liquid oxygen supply system in April 1990. Three types of portable oxygen delivery systems are available; oxygen cyclinder, liquid oxygen system, and oxygen concentrator (membrane type), of which the oxygen cylinder is most commonly used. In our hospital, portable oxygen supply systems were used in 80% of 168 HOT cases in 1990, and the use of 400 L aluminum oxygen cylinders at a flow rate of 1-2 L/min has been most popular. There is an strong desire from patients for lighter portable oxygen supply system of longer duration. In 19 patients with chronic respiratory failure, we evaluated a newly designed demand oxygen delivery system (DODS), which weighs 2.4 kg including the DOD device (TER-20 Teijin), 1.1 L oxygen cylinder made of ultressor, nasal cannula, and carrier. Arterial blood gases at rest (room air) were PaO2 61.9 +/- 6.3 torr, PaCO2 63.8 +/- 9.4 torr and pH 7.40 +/- 0.04. A crossover trial was performed under three conditions; breathing room air with no weight, and pulse oxygen flow and continuous oxygen flow each carrying 2.4 kg of weight. Both 6 minute walking (E1) and walking on a slow speed treadmill (E2) were studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Utilization of Renewable Oxygenates as Gasoline Blending Components

Energy Technology Data Exchange (ETDEWEB)

Yanowitz, J.; Christensen, E.; McCormick, R. L.

2011-08-01

This report reviews the use of higher alcohols and several cellulose-derived oxygenates as blend components in gasoline. Material compatibility issues are expected to be less severe for neat higher alcohols than for fuel-grade ethanol. Very little data exist on how blending higher alcohols or other oxygenates with gasoline affects ASTM Standard D4814 properties. Under the Clean Air Act, fuels used in the United States must be 'substantially similar' to fuels used in certification of cars for emission compliance. Waivers for the addition of higher alcohols at concentrations up to 3.7 wt% oxygen have been granted. Limited emission testing on pre-Tier 1 vehicles and research engines suggests that higher alcohols will reduce emissions of CO and organics, while NOx emissions will stay the same or increase. Most oxygenates can be used as octane improvers for standard gasoline stocks. The properties of 2-methyltetrahydrofuran, dimethylfuran, 2-methylfuran, methyl pentanoate and ethyl pentanoate suggest that they may function well as low-concentration blends with gasoline in standard vehicles and in higher concentrations in flex fuel vehicles.

Comparison of the OxyMask and Venturi Mask in the Delivery of Supplemental Oxygen: Pilot Study in Oxygen-Dependent Patients

Directory of Open Access Journals (Sweden)

Jaime M Beecroft

2006-01-01

Full Text Available BACKGROUND: The OxyMask (Southmedic Inc, Canada is a new face mask for oxygen delivery that uses a small ‘diffuser’ to concentrate and direct oxygen toward the mouth and nose. The authors hypothesized that this unique design would enable the OxyMask to deliver oxygen more efficiently than a Venturi mask (Hudson RCI, USA in patients with chronic hypoxemia.

Oxygen intrusion into anoxic fjords leads to increased methylmercury availability

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Veiteberg Braaten, Hans Fredrik; Pakhomova, Svetlana; Yakushev, Evgeniy

2013-04-01

surface layer to 6.5 ng/L at maximum depth (10 m). However, the pattern of MeHg concentrations in the water column changed with relatively high concentrations present already at 4.5 m depth (2.2 ng/L). The environmental consequence of this oxygen intrusion is the appearance in shallower water of toxic MeHg formed in the anoxic layer. As a result of this, MeHg can possibly undergo transport from the anoxic fjord to the surrounding areas.

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

International Nuclear Information System (INIS)

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

[Effect of oxygen tubing connection site on percutaneous oxygen partial pressure and percutaneous carbon dioxide partial pressure in patients with chronic obstructive pulmonary disease during noninvasive positive pressure ventilation].

Science.gov (United States)

Mi, S; Zhang, L M

2017-04-12

Objective: We evaluated the effects of administering oxygen through nasal catheters inside the mask or through the mask on percutaneous oxygen partial pressure (PcO(2))and percutaneous carbon dioxide partial pressure (PcCO(2)) during noninvasive positive pressure ventilation (NPPV) to find a better way of administering oxygen, which could increase PcO(2) by increasing the inspired oxygen concentration. Methods: Ten healthy volunteers and 9 patients with chronic obstructive pulmonary disease complicated by type Ⅱ respiratory failure were included in this study. Oxygen was administered through a nasal catheter inside the mask or through the mask (oxygen flow was 3 and 5 L/min) during NPPV. PcO(2) and PcCO(2) were measured to evaluate the effects of administering oxygen through a nasal catheter inside the mask or through the mask, indirectly reflecting the effects of administering oxygen through nasal catheter inside the mask or through the mask on inspired oxygen concentration. Results: Compared to administering oxygen through the mask during NPPV, elevated PcO(2) was measured in administering oxygen through the nasal catheter inside the mask, and the differences were statistically significant ( P 0.05). Conclusion: Administering oxygen through a nasal catheter inside the mask during NPPV increased PcO(2) by increasing the inspired oxygen concentration but did not increase PcCO(2). This method of administering oxygen could conserve oxygen and be suitable for family NPPV. Our results also provided theoretical basis for the development of new masks.

High-Energy-Density Metal-Oxygen Batteries: Lithium-Oxygen Batteries vs Sodium-Oxygen Batteries.

Science.gov (United States)

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.

Sensing performances of ZnO nanostructures grown under different oxygen pressures to hydrogen

International Nuclear Information System (INIS)

Chu, Jin; Peng, Xiaoyan; Wang, Zhenbo; Feng, Peter

2012-01-01

Graphical abstract: Display Omitted Highlights: ► Surface morphology depends on the oxygen pressure. ► Structural degradation was observed for the ZnO samples when oxygen pressure was overhigh. ► The sensitivity of the ZnO-based sensors increase with grown oxygen pressure. -- Abstract: For extensive use in an industrialized process of individual ZnO nanostructures applied in gas sensors, a simple, inexpensive, and safe synthesis process is required. Here, nanostructured ZnO films were grown by a pulsed laser deposition technique under different oxygen pressures. Scanning electron microscopy images show nanopores, nanotips, and nanoparticles are obtained and energy dispersive X-ray spectroscopy data indicate oxygen concentration of the synthesized samples increases monotonously with oxygen pressure. The sensor based on ZnO with high oxygen concentration has high sensitivity, rapid response (9 s) and recovery (80 s) behavior to 500 ppm hydrogen below 150 °C. Experimental data indicate that high oxygen concentration effectively improves the sensing properties of nanostructured ZnO.

Accumulation of Fe oxyhydroxides in the Peruvian oxygen deficient zone implies non-oxygen dependent Fe oxidation

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Heller, Maija I.; Lam, Phoebe J.; Moffett, James W.; Till, Claire P.; Lee, Jong-Mi; Toner, Brandy M.; Marcus, Matthew A.

2017-08-01

Oxygen minimum zones (OMZs) have been proposed to be an important source of dissolved iron (Fe) into the interior ocean. However, previous studies in OMZs have shown a sharp decrease in total dissolved Fe (dFe) and/or dissolved Fe(II) (dFe(II)) concentrations at the shelf-break, despite constant temperature, salinity and continued lack of oxygen across the shelf-break. The loss of both total dFe and dFe(II) suggests a conversion of the dFe to particulate form, but studies that have coupled the reduction-oxidation (redox) speciation of both dissolved and particulate phases have not previously been done. Here we have measured the redox speciation and concentrations of both dissolved and particulate forms of Fe in samples collected during the U.S. GEOTRACES Eastern tropical Pacific Zonal Transect (EPZT) cruise in 2013 (GP16). This complete data set allows us to assess possible mechanisms for loss of dFe. We observed an offshore loss of dFe(II) within the oxygen deficient zone (ODZ), where dissolved oxygen is undetectable, accompanied by an increase in total particulate Fe (pFe). Total pFe concentrations were highest in the upper ODZ. X-ray absorption spectroscopy revealed that the pFe maximum was primarily in the Fe(III) form as Fe(III) oxyhydroxides. The remarkable similarity in the distributions of total particulate iron and nitrite suggests a role for nitrite in the oxidation of dFe(II) to pFe(III). We present a conceptual model for the rapid redox cycling of Fe that occurs in ODZs, despite the absence of oxygen.

Growth and Properties of Oxygen and Ion Doped BISMUTH(2) STRONTIUM(2) Calcium COPPER(2) Oxygen (8+DELTA) Single Crystals

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Mitzi, David Brian

1990-01-01

A directional solidification method for growing large single crystals in the Bi_2Sr _2CaCu_2O _{8+delta} system is reported. Ion substitutions, with replacement of La for Sr and Y for Ca, as well as oxygen doping in these crystals has been explored. Ion doping results in little change of the superconducting transition for substitution levels below 20-25% (as a result of simultaneous oxygen intercalation), while beyond this level, the Meissner signal broadens and the low temperature Meissner signal decreases. Microprobe analysis and x-ray diffraction performed on these more highly substituted single crystals, provides evidence for inhomogeneity and phase segregation into regions of distinct composition. Annealing unsubstituted crystals in increasing partial pressures of oxygen reversibly depresses the superconducting transition temperature from 90K (as made) to 77K (oxygen pressure annealed) while the Hall concentrations increase from n = 3.1(3) times 10 ^{21} cm^{ -3} (0.34 holes/Cu site) to 4.6(3) times 10^{21} cm^{-3} (0.50 holes/Cu site). Further suppression of T_{c} to 72K is possible by annealing in oxygen pressures up to 100atm. No degradation of the Meissner transition or other indications of inhomogeneity or phase segregation with doping are noted, suggesting that oxygen doped Bi_2Sr _2CaCu_2O _{8+delta} is a suitable system for pursuing doping studies. The decrease in T _{c} with concentration for 0.34 <=q n <=q 0.50 indicates that a high carrier concentration regime exists where T_{c} decreases with n and suggests that this decrease does not arise from material inhomogeneity or other materials problems. The physical properties of these Bi _2Sr_2CaCu _2O_{8+delta} crystals, in this high carrier concentration regime, will be discussed.

Singlet oxygen treatment of tumor cells triggers extracellular singlet oxygen generation, catalase inactivation and reactivation of intercellular apoptosis-inducing signaling☆

Science.gov (United States)

Riethmüller, Michaela; Burger, Nils; Bauer, Georg

2015-01-01

Intracellular singlet oxygen generation in photofrin-loaded cells caused cell death without discrimination between nonmalignant and malignant cells. In contrast, extracellular singlet oxygen generation caused apoptosis induction selectively in tumor cells through singlet oxygen-mediated inactivation of tumor cell protective catalase and subsequent reactivation of intercellular ROS-mediated apoptosis signaling through the HOCl and the NO/peroxynitrite signaling pathway. Singlet oxygen generation by extracellular photofrin alone was, however, not sufficient for optimal direct inactivation of catalase, but needed to trigger the generation of cell-derived extracellular singlet oxygen through the interaction between H2O2 and peroxynitrite. Thereby, formation of peroxynitrous acid, generation of hydroxyl radicals and formation of perhydroxyl radicals (HO2.) through hydroxyl radical/H2O2 interaction seemed to be required as intermediate steps. This amplificatory mechanism led to the formation of singlet oxygen at a sufficiently high concentration for optimal inactivation of membrane-associated catalase. At low initial concentrations of singlet oxygen, an additional amplification step needed to be activated. It depended on singlet oxygen-dependent activation of the FAS receptor and caspase-8, followed by caspase-8-mediated enhancement of NOX activity. The biochemical mechanisms described here might be considered as promising principle for the development of novel approaches in tumor therapy that specifically direct membrane-associated catalase of tumor cells and thus utilize tumor cell-specific apoptosis-inducing ROS signaling. PMID:26225731