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Sample records for oxygen production rate

  1. Oxygen transfer rate during the production of alginate by Azotobacter vinelandii under oxygen-limited and non oxygen-limited conditions

    Directory of Open Access Journals (Sweden)

    Peña Carlos F

    2011-02-01

    Full Text Available Abstract Background The oxygen transfer rate (OTR and dissolved oxygen tension (DOT play an important role in determining alginate production and its composition; however, no systematic study has been reported about the independent influence of the OTR and DOT. In this paper, we report a study about alginate production and the evolution of the molecular mass of the polymer produced by a wild-type A. vinelandii strain ATCC 9046, in terms of the maximum oxygen transfer rate (OTRmax in cultures where the dissolved oxygen tension (DOT was kept constant. Results The results revealed that in the two dissolved oxygen conditions evaluated, strictly controlled by gas blending at 0.5 and 5% DOT, an increase in the agitation rate (from 300 to 700 rpm caused a significant increase in the OTRmax (from 17 to 100 mmol L-1 h-1 for DOT of 5% and from 6 to 70 mmol L-1 h-1 for DOT of 0.5%. This increase in the OTRmax improved alginate production, as well as the specific alginate production rate (SAPR, reaching a maximal alginate concentration of 3.1 g L-1 and a SAPR of 0.031 g alg g biom-1 h-1 in the cultures at OTRmax of 100 mmol L-1 h-1. In contrast, the mean molecular mass (MMM of the alginate isolated from cultures developed under non-oxygen limited conditions increased by decreasing the OTRmax, reaching a maximal of 550 kDa at an OTRmax of 17 mmol L-1 h-1 . However, in the cultures developed under oxygen limitation (0.5% DOT, the MMM of the polymer was practically the same (around 200 kDa at 300 and 700 rpm, and this remained constant throughout the cultivation. Conclusions Overall, our results showed that under oxygen-limited and non oxygen-limited conditions, alginate production and its molecular mass are linked to the OTRmax, independently of the DOT of the culture.

  2. The determination and analysis of site-specific rates of mitochondrial reactive oxygen species production

    DEFF Research Database (Denmark)

    Quinlan, Casey L; Perevoschikova, Irina V; Goncalves, Renata L S

    2013-01-01

    Mitochondrial reactive oxygen species (ROS) are widely implicated in physiological and pathological pathways. We propose that it is critical to understand the specific sites of mitochondrial ROS production and their mechanisms of action. Mitochondria possess at least eight distinct sites of ROS...... production in the electron transport chain and matrix compartment. In this chapter, we describe the nature of the mitochondrial ROS-producing machinery and the relative capacities of each site. We provide detailed methods for the measurement of H2O2 release and the conditions under which maximal rates from...

  3. 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

  4. Characterization of Adipose Tissue Product Quality Using Measurements of Oxygen Consumption Rate.

    Science.gov (United States)

    Suszynski, Thomas M; Sieber, David A; Mueller, Kathryn; Van Beek, Allen L; Cunningham, Bruce L; Kenkel, Jeffrey M

    2018-03-14

    Fat grafting is a common procedure in plastic surgery but associated with unpredictable graft retention. Adipose tissue (AT) "product" quality is affected by the methods used for harvest, processing and transfer, which vary widely amongst surgeons. Currently, there is no method available to accurately assess the quality of AT. In this study, we present a novel method for the assessment of AT product quality through direct measurements of oxygen consumption rate (OCR). OCR has exhibited potential in predicting outcomes following pancreatic islet transplant. Our study aim was to reapportion existing technology for its use with AT preparations and to confirm that these measurements are feasible. OCR was successfully measured for en bloc and postprocessed AT using a stirred microchamber system. OCR was then normalized to DNA content (OCR/DNA), which represents the AT product quality. Mean (±SE) OCR/DNA values for fresh en bloc and post-processed AT were 149.8 (± 9.1) and 61.1 (± 6.1) nmol/min/mg DNA, respectively. These preliminary data suggest that: (1) OCR and OCR/DNA measurements of AT harvested using conventional protocol are feasible; and (2) standard AT processing results in a decrease in overall AT product quality. OCR measurements of AT using existing technology can be done and enables accurate, real-time, quantitative assessment of the quality of AT product prior to transfer. The availability and further validation of this type of assay could enable optimization of fat grafting protocol by providing a tool for the more detailed study of procedural variables that affect AT product quality.

  5. Rates and products of degradation for MTBE and other oxygenate fuel additives in the subsurface environment

    International Nuclear Information System (INIS)

    Tratnyek, P.G.; Church, C.D.; Pankow, J.F.

    1995-01-01

    The recent realization that oxygenated fuel additives such as MTBE are becoming widely distributed groundwater contaminants has created a sudden and pressing demand for data on the processes that control their environmental fate. Explaining and predicting the subsequent environmental fate of these compounds is going to require extrapolations over long time frames that will be very sensitive to the quality of input data on each compound. To provide such data, they have initiated a systematic study of the pathways and kinetics of fuel oxygenate degradation under subsurface conditions. Batch experiments in simplified model systems are being performed to isolate specific processes that may contribute to MTBE degradation. A variety of degradation pathways can be envisioned that lead to t-butyl alcohol (TBA) as the primary or secondary product. However, experiments to date with a facultative iron reducing bacteria showed no evidence for TBA formation. Continuing experiments include mixed cultures from a range of aquifer materials representative of NAWQA study sites

  6. Effects of dissolved oxygen and pH on nitrous oxide production rates in autotrophic partial nitrification granules.

    Science.gov (United States)

    Rathnayake, Rathnayake M L D; Oshiki, Mamoru; Ishii, Satoshi; Segawa, Takahiro; Satoh, Hisashi; Okabe, Satoshi

    2015-12-01

    The effects of dissolved oxygen (DO) and pH on nitrous oxide (N2O) production rates and pathways in autotrophic partial nitrification (PN) granules were investigated at the granular level. N2O was primarily produced by betaproteobacterial ammonia-oxidizing bacteria, mainly Nitrosomonas europaea, in the oxic surface layer (production increased with increasing bulk DO concentration owing to activation of the ammonia (i.e., hydroxylamine) oxidation in this layer. The highest N2O emissions were observed at pH 7.5, although the ammonia oxidation rate was unchanged between pH 6.5 and 8.5. Overall, the results of this study suggest that in situ analyses of PN granules are essential to gaining insight into N2O emission mechanisms in a granule. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. N2 production rates limited by nitrite availability in the Bay of Bengal oxygen minimum zone

    DEFF Research Database (Denmark)

    Bristow, Laura A.; Callbeck, C. M.; Larsen, M

    2017-01-01

    with isotopically labelled nitrogen compounds and analyse geochemical signatures of these processes in the water column. We find that the Bay of Bengal supports denitrifier and anammox microbial populations, mediating low, but significant N loss. Yet, unlike other oxygen minimum zones, our measurements using...

  8. N2 production rates limited by nitrite availability in the Bay of Bengal oxygen minimum zone

    Digital Repository Service at National Institute of Oceanography (India)

    Bristow, L.A; Callbeck, C.M.; Larsen, M.; Altabet, M.A; Dekaezemacker, J.; Forth, M.; Gauns, M.; Glud, R.N.; Kuypers, M.M.M.; Lavik, G.; Milucka, J.; Naqvi, S.W.A; Pratihary, A; Revsbech, N.P.; Thamdrup, B.; Treusch, A; Canfield, D.E.

    A third or more of the fixed nitrogen lost from the oceans as N2 is removed by anaerobic microbial processes in open ocean oxygen minimum zones. These zones have expanded over the past decades, and further anthropogenically induced...

  9. Respiration and substrate transport rates as well as reactive oxygen species production distinguish mitochondria from brain and liver.

    Science.gov (United States)

    Gusdon, Aaron M; Fernandez-Bueno, Gabriel A; Wohlgemuth, Stephanie; Fernandez, Jenelle; Chen, Jing; Mathews, Clayton E

    2015-09-10

    Aberrant mitochondrial function, including excessive reactive oxygen species (ROS) production, has been implicated in the pathogenesis of human diseases. The use of mitochondrial inhibitors to ascertain the sites in the electron transport chain (ETC) resulting in altered ROS production can be an important tool. However, the response of mouse mitochondria to ETC inhibitors has not been thoroughly assessed. Here we set out to characterize the differences in phenotypic response to ETC inhibitors between the more energetically demanding brain mitochondria and less energetically demanding liver mitochondria in commonly utilized C57BL/6J mice. We show that in contrast to brain mitochondria, inhibiting distally within complex I or within complex III does not increase liver mitochondrial ROS production supported by complex I substrates, and liver mitochondrial ROS production supported by complex II substrates occurred primarily independent of membrane potential. Complex I, II, and III enzymatic activities and membrane potential were equivalent between liver and brain and responded to ETC. inhibitors similarly. Brain mitochondria exhibited an approximately two-fold increase in complex I and II supported respiration compared with liver mitochondria while exhibiting similar responses to inhibitors. Elevated NADH transport and heightened complex II-III coupled activity accounted for increased complex I and II supported respiration, respectively in brain mitochondria. We conclude that important mechanistic differences exist between mouse liver and brain mitochondria and that mouse mitochondria exhibit phenotypic differences compared with mitochondria from other species.

  10. Production, oxygen respiration rates, and sinking velocity of copepod fecal pellets: Direct measurements of ballasting by opal and calcite

    DEFF Research Database (Denmark)

    Ploug, H.; Iversen, M.H.; Koski, Marja

    2008-01-01

    sp., T. weissflogii, and E. huxleyi, respectively. The average carbon-specific respiration rate was 0.15 d(-1) independent on diet (range: 0.08-0.21 d(-1)). Because of ballasting of opal and calcite, sinking velocities were significantly higher for pellets produced on T. weissflogii (322 +/- 169 m d...

  11. Oxygen uptake rate (OUR) control strategy for improving avermectin B

    African Journals Online (AJOL)

    Glucose metabolism plays a crucial role in the process of avermectin B1a biosynthesis. Controlling glucose feeding based on oxygen uptake rate (OUR) was established to improve the efficiency of avermectin B1a production. The result showed that avermectin B1a production was greatly enhanced by OUR control strategy.

  12. Mars oxygen production system design

    Science.gov (United States)

    Cotton, Charles E.; Pillow, Linda K.; Perkinson, Robert C.; Brownlie, R. P.; Chwalowski, P.; Carmona, M. F.; Coopersmith, J. P.; Goff, J. C.; Harvey, L. L.; Kovacs, L. A.

    1989-01-01

    The design and construction phase is summarized of the Mars oxygen demonstration project. The basic hardware required to produce oxygen from simulated Mars atmosphere was assembled and tested. Some design problems still remain with the sample collection and storage system. In addition, design and development of computer compatible data acquisition and control instrumentation is ongoing.

  13. Production of Lunar Oxygen Through Vacuum Pyrolysis

    National Research Council Canada - National Science Library

    Matchett, John

    2006-01-01

    .... The vacuum pyrolysis method of oxygen production from lunar regolith presents a viable option for in situ propellant production because of its simple operation involving limited resources from earth...

  14. Design of a lunar oxygen production plant

    Science.gov (United States)

    Radhakrishnan, Ramalingam

    1990-01-01

    To achieve permanent human presence and activity on the moon, oxygen is required for both life support and propulsion. Lunar oxygen production using resources existing on the moon will reduce or eliminate the need to transport liquid oxygen from earth. In addition, the co-products of oxygen production will provide metals, structural ceramics, and other volatile compounds. This will enable development of even greater self-sufficiency as the lunar outpost evolves. Ilmenite is the most abundant metal-oxide mineral in the lunar regolith. A process involving the reaction of ilmenite with hydrogen at 1000 C to produce water, followed by the electrolysis of this water to provide oxygen and recycle the hydrogen has been explored. The objective of this 1990 Summer Faculty Project was to design a lunar oxygen-production plant to provide 5 metric tons of liquid oxygen per year from lunar soil. The results of this study describe the size and mass of the equipment, the power needs, feedstock quantity and the engineering details of the plant.

  15. Determination of Biological Oxygen Demand Rate Constant and ...

    African Journals Online (AJOL)

    Determination of Biological Oxygen Demand Rate Constant and Ultimate Biological Oxygen Demand for Liquid Waste Generated from Student Cafeteria at Jimma University: A Tool for Development of Scientific Criteria to Protect Aquatic Health in the Region.

  16. Net Community and Gross Photosynthetic Production Rates in the Eastern Tropical South Pacific, as Determined from O2/AR Ratios and Triple Oxygen Isotopic Composition of Dissolved O2

    Science.gov (United States)

    Prokopenko, M. G.; Yeung, L. Y.; Berelson, W.; Fleming, J.; Rollins, N.; Young, E. D.; Haskell, W. Z.; Hammond, D. E.; Capone, D. G.

    2010-12-01

    This study assesses the rates of ocean carbon production and its fate with respect to recycling or export in the Eastern Tropical South Pacific (ETSP). ETSP has been previously identified as a region where N2 fixation and denitrification may be spatially coupled; this is also a region of localized CO2 outgassing. Using an Equilibrated Inlet Mass Spectrometer (EIMS) system, we obtained continuous measurements of the biological O2 supersaturation in the mixed layer along the ship track encompassing a region bounded by 10-20° S and 80-100° W in January - March, 2010. Vertical profiles were also taken at selected stations and analyzed for dissolved O2/Ar ratios on EIMS and triple oxygen isotope composition (17O excess) on a multi-collector IRMS (Isotope Ratio Mass Spectrometer) at UCLA. Gas exchange rates were estimated using two approaches: the Rn-222 deficit method and the wind parameterization method, which utilized wind speeds extracted from ASCAT satellite database. Oxygen Net Community Production (O-NCP) rates calculated based on biological O2 supersaturation ranged from slightly negative to ~ 0.3 - 15 mmol/m2d, with higher rates along the northern part of the transect. Oxygen Gross Community Production (O-GPP) rates calculated from 17O excess were between 50 ± 20 and 200 ± 40 mmol/m2d, with higher rates observed along the northern cruise transect as well. Notably, the NCP/GPP ratios along the northern transect were higher by the factor of 2 to 3 than their southern counterparts. The O2/Ar-based NCP rates were comparable to POC flux measured with floating traps deployed at the southern stations, but exceeded by a factor of 5-10 the trap POC fluxes obtained at the northern stations. A one-dimensional box model has been constructed to quantify the magnitude of oxygen primary production below the mixed layer. The results of this work will be integrated with measurements of 15-N2 uptake that are in progress, to constrain the potential contribution of N2 fixation

  17. Aquatic respiration rate measurements at low oxygen concentrations.

    Directory of Open Access Journals (Sweden)

    Moritz Holtappels

    Full Text Available Despite its huge ecological importance, microbial oxygen respiration in pelagic waters is little studied, primarily due to methodological difficulties. Respiration measurements are challenging because of the required high resolution of oxygen concentration measurements. Recent improvements in oxygen sensing techniques bear great potential to overcome these limitations. Here we compare 3 different methods to measure oxygen consumption rates at low oxygen concentrations, utilizing amperometric Clark type sensors (STOX, optical sensors (optodes, and mass spectrometry in combination with (18-18O2 labeling. Oxygen concentrations and consumption rates agreed well between the different methods when applied in the same experimental setting. Oxygen consumption rates between 30 and 400 nmol L(-1 h(-1 were measured with high precision and relative standard errors of less than 3%. Rate detection limits in the range of 1 nmol L(-1 h(-1 were suitable for rate determinations in open ocean water and were lowest at the lowest applied O2 concentration.

  18. Effect of oxygen treatment on heart rate after abdominal surgery

    DEFF Research Database (Denmark)

    Rosenberg-Adamsen, S; Lie, C; Bernhard, A

    1999-01-01

    BACKGROUND: Cardiac complications are common during the postoperative period and may be associated with hypoxemia and tachycardia. Preliminary studies in high-risk patients after operation have shown a possible beneficial effect of oxygen therapy on arterial oxygen saturation and heart rate....... METHODS: The authors studied the effect of oxygen therapy on arterial oxygen saturation and heart rate in 100 consecutive unselected patients randomly and double blindly allocated to receive air or oxygen therapy between the first and fourth day after major abdominal surgery. RESULTS: The median arterial...... oxygen saturation rate increased significantly from 96% to 99% (P heart rate decreased significantly from 85 beats/min to 81 beats/min (P heart rate occurred...

  19. Oxygen respiration rates of benthic foraminifera as measured with oxygen microsensors

    DEFF Research Database (Denmark)

    Geslin, E.; Risgaard-Petersen, N.; Lombard, Fabien

    2011-01-01

    of the foraminiferal specimens. The results show a wide range of oxygen respiration rates for the different species (from 0.09 to 5.27 nl cell−1 h−1) and a clear correlation with foraminiferal biovolume showed by the power law relationship: R = 3.98 10−3 BioVol0.88 where the oxygen respiration rate (R) is expressed......Oxygen respiration rates of benthic foraminifera are still badly known, mainly because they are difficult to measure. Oxygen respiration rates of seventeen species of benthic foraminifera were measured using microelectrodes and calculated on the basis of the oxygen fluxes measured in the vicinity...... groups (nematodes, copepods, ostracods, ciliates and flagellates) suggests that benthic foraminifera have a lower oxygen respiration rates per unit biovolume. The total contribution of benthic foraminifera to the aerobic mineralisation of organic matter is estimated for the studied areas. The results...

  20. Oxygen-controlled Biosurfactant Production in a Bench Scale Bioreactor

    Science.gov (United States)

    de Kronemberger, Frederico Araujo; Anna, Lidia Maria Melo Santa; Fernandes, Ana Carolina Loureiro Brito; de Menezes, Reginaldo Ramos; Borges, Cristiano Piacsek; Freire, Denise Maria Guimarães

    Rhamnolipids have been pointed out as promising biosurfactants. The most studied microorganisms for the aerobic production of these molecules are the bacteria of the genus Pseudomonas. The aim of this work was to produce a rhamnolipid-type biosurfactant in a bench-scale bioreactor by one strain of Pseudomonas aeruginosa isolated from oil environments. To study the microorganism growth and production dependency on oxygen, a nondispersive oxygenation device was developed, and a programmable logic controller (PLC) was used to set the dissolved oxygen (DO) concentration. Using the data stored in a computer and the predetermined characteristics of the oxygenation device, it was possible to evaluate the oxygen uptake rate (OUR) and the specific OUR (SOUR) of this microorganism. These rates, obtained for some different DO concentrations, were then compared to the bacterial growth, to the carbon source consumption, and to the rhamnolipid and other virulence factors production. The SOUR presented an initial value of about 60.0 mg02/gdw h. Then, when the exponential growth phase begins, there is a rise in this rate. After that, the SOUR reduces to about 20.0 mg02/gdw h. The carbon source consumption is linear during the whole process.

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

    Science.gov (United States)

    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.

  2. Sorbent-based Oxygen Production for Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Sethi, Vijay [Western Research Inst. (WRI), Laramie, WY (United States)

    2017-01-31

    Project DE-FE0024075 deals with the development of a moderate-temperature sorbent-based oxygen production technology. Sorbent-based oxygen production process utilizes oxygen-storage properties of Perovskites to (1) adsorb oxygen from air in a solid sorbent, and (2) release the adsorbed oxygen into a sweep gas such as CO2 and/or steam for gasification systems or recycled flue gas for oxy-combustion systems. Pure oxygen can be produced by the use of vacuum instead of a sweep gas to affect the pressure swing. By developing more efficient and stable, higher sorption capacity, newer class of materials operating at moderate temperatures this process represents a major advancement in air separation technology. Newly developed perovskite ceramic sorbent materials with order-disorder transition have a higher O2 adsorption capacity, potentially 200 °C lower operating temperatures, and up to two orders of magnitude faster desorption rates than those used in earlier development efforts. The performance advancements afforded by the new materials lead to substantial savings in capital investment and operational costs. Cost of producing oxygen using sorbents could be as much as 26% lower than VPSA and about 13% lower than a large cryogenic air separation unit. Cost advantage against large cryogenic separation is limited because sorbent-based separation numbers up sorbent modules for achieving the larger capacity.

  3. Thermal design of a Mars oxygen production plant

    Science.gov (United States)

    Sridhar, K. R.; Iyer, Venkatesh A.

    1991-01-01

    The optimal design of the thermal components of a system that uses carbon dioxide from the Martian atmosphere to produce oxygen for spacecraft propulsion and/or life support is discussed. The gases are pressurized, heated and passed through an electrochemical cell. Carbon dioxide is reduced to carbon monoxide and oxygen due to thermal dissociation and electrocatalysis. The oxygen thus formed is separated from the gas mixture by the electrochemical cell. The objective of the design is to optimize both the overall mass and the power consumption of the system. The analysis shows that at electrochemical cell efficiencies of about 50 percent and lower, the optimal system would require unspent carbon dioxide in the exhaust gases to be separated and recycled. Various methods of efficiently compressing the intake gases to system pressures of 0.1 MPa are investigated. The total power requirement for oxygen production rates of 1, 5, and 10 kg/day at various cell efficiencies are presented.

  4. Integration of oxygen membranes for oxygen production in cement plants

    DEFF Research Database (Denmark)

    Puig Arnavat, Maria; Søgaard, Martin; Hjuler, Klaus

    2015-01-01

    The present paper describes the integration of oxygen membranes in cement plants both from an energy, exergy and economic point of view. Different configurations for oxygen enrichment of the tertiary air for combustion in the pre-calciner and full oxy-fuel combustion in both pre-calciner and kiln...

  5. Ozone Production Using Pulsed Dielectric Barrier Discharge in Oxygen

    OpenAIRE

    Samaranayake, W. J. M.; Miyahara, Y.; Namihira, T.; Katsuki, S.; Hackam, R.; Akiyama, H.; ナミヒラ, タカオ; カツキ, スナオ; アキヤマ, ヒデノリ; 浪平, 隆男; 勝木, 淳; 秋山, 秀典

    2000-01-01

    The production of ozone was investigated using a dielectric barrier discharge in oxygen, and employing short-duration pulsed power. The dependence of the ozone concentration (parts per million, ppm) and ozone production yield (g(O3)/kWh) on the peak pulsed voltage (17.5 to 57.9 kV) and the pulse repetition rate (25 to 400 pulses/s, pps) were investigated. In the present study, the following parameters were kept constant: a pressure of 1.01×105 Pa, a temperature of 26±4°C a gas flow rate of 3....

  6. Recent advances in oxygen production for gasification

    Energy Technology Data Exchange (ETDEWEB)

    Gunardson, H.H. [Air Products Canada Ltd., Mississauga, ON (Canada)

    2005-07-01

    This paper described the Ionic Transport Membrane (ITM) technology that reduces the overall cost of the gasification process by 7 per cent. Gasification is a proven, but expensive technology for producing hydrogen and synthesis gas from low cost hydrocarbon feedstock. Gasification is also an alternative to conventional steam methane reforming based on natural gas. A key cost element in gasification is the production of oxygen. For that reason, Air Products Canada Limited developed a ceramic membrane air separation technology that can reduce the cost of pure oxygen by more than 30 per cent. The separation technology achieves a capital cost reduction of 30 per cent and an energy reduction of 35 per cent over conventional cryogenic air separation. ITM is an electrochemical process that integrates very well with the gasification process and an integrated gasification combined cycle (IGCC) option for production of electrical power from the waste heat generated from gasification. This paper described the integration of ITM technology with both the gasification and IGCC processes and showed how the superior economics of ITM can allow gasification to compete with steam methane reforming and thereby reduce dependency of oil sands development on increasingly scarce and costly natural gas.

  7. Rate of reaction of dimethylmercury with oxygen atoms in the gas phase

    DEFF Research Database (Denmark)

    Egsgaard, Helge

    1986-01-01

    The rate constant for the reaction of atomic oxygen (O(3P)) with dimethylmercury has been measured at room temperature at a pressure of about 1 Torr using a fast flow system with electron paramagnetic resonance and mass spectrometric detection. Some reaction products were identified. The rate...

  8. In-Situ Resource Utilization: Oxygen Production

    Data.gov (United States)

    National Aeronautics and Space Administration — The leading option for extracting oxygen from the Mars atmospheric carbon dioxide is to use a solid oxide electrolyzer, which removes one oxygen atom from the CO2...

  9. Report on ISS Oxygen Production, Resupply, and Partial Pressure Management

    Science.gov (United States)

    Schaezler, Ryan; Ghariani, Ahmed; Leonard, Daniel; Lehman, Daniel

    2011-01-01

    The majority of oxygen used on International Space Station (ISS) is for metabolic support and denitrogenation procedures prior to Extra-Vehicular Activities. Oxygen is supplied by various visiting vehicles such as the Progress and Shuttle in addition to oxygen production capability on both the United States On-Orbit Segment (USOS) and Russian Segment (RS). To maintain a habitable atmosphere the oxygen partial pressure is controlled between upper and lower bounds. The full range of the allowable oxygen partial pressure along with the increased ISS cabin volume is utilized as a buffer allowing days to pass between oxygen production or direct addition of oxygen to the atmosphere from reserves. This paper summarizes amount of oxygen supplied and produced from all of the sources and describes past experience of managing oxygen partial pressure along with the range of management options available to the ISS.

  10. Measurement of oxygen consumption rate of osteoblasts from ...

    African Journals Online (AJOL)

    The cells were evaluated through live/dead assay, hematoxylin-eosin (HE) and alkaline phosphatase (ALP) staining. Moreover, Von-Kossa staining and Alizarin Red S staining were carried out for mineralized nodule formation. Following this, the oxygen consumption rates of osteoblasts in the earlier mentioned different ...

  11. Dynamic molecular oxygen production in cometary comae

    Science.gov (United States)

    Yao, Yunxi; Giapis, Konstantinos P.

    2017-05-01

    Abundant molecular oxygen was discovered in the coma of comet 67P/Churyumov-Gerasimenko. Its origin was ascribed to primordial gaseous O2 incorporated into the nucleus during the comet's formation. This thesis was put forward after discounting several O2 production mechanisms in comets, including photolysis and radiolysis of water, solar wind-surface interactions and gas-phase collisions. Here we report an original Eley-Rideal reaction mechanism, which permits direct O2 formation in single collisions of energetic water ions with oxidized cometary surface analogues. The reaction proceeds by H2O+ abstracting a surface O-atom, then forming an excited precursor state, which dissociates to produce O2-. Subsequent photo-detachment leads to molecular O2, whose presence in the coma may thus be linked directly to water molecules and their interaction with the solar wind. This abiotic O2 production mechanism is consistent with reported trends in the 67P coma and raises awareness of the role of energetic negative ions in comets.

  12. Rate of oxygen isotope exchange between selenate and water.

    Science.gov (United States)

    Kaneko, Masanori; Poulson, Simon R

    2012-04-17

    The rate of oxygen isotope exchange between selenate and water was investigated at conditions of 10 to 80 °C and pH -0.6 to 4.4. Oxygen isotope exchange proceeds as a first-order reaction, and the exchange rate is strongly affected by reaction temperature and pH, with increased rates of isotope exchange at higher temperature and lower pH. Selenate speciation (HSeO(4)(-) vs SeO(4)(2-)) also has a significant effect on the rate of isotope exchange. The half-life for isotope exchange at example natural conditions (25 °C and pH 7) is estimated to be significantly in excess of 10(6) years. The very slow rate of oxygen isotope exchange between selenate and water under most environmental conditions demonstrates that selenate-δ(18)O signatures produced by biogeochemical processes will be preserved and hence that it will be possible to use the value of selenate-δ(18)O to investigate the biogeochemical behavior of selenate, in an analogous fashion to the use of sulfate-δ(18)O to study the biogeochemical behavior of sulfate.

  13. Determination of rate constants for the oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Racz, A.; Walter, T.; Stimming, U. [Munich Technical Univ., Garching (Germany). Dept. of Physics

    2008-07-01

    The oxygen reduction reaction (ORR) in fuel cells is a complex and fundamental electrochemical reaction. However, greater insight is needed into this multi-electron reaction in order to develop efficient and innovative catalysts. The rotating ring disc electrode (RRDE) is a useful tool for studying reaction intermediates of the ORR and to better understand the reaction pathway. Carbon materials such as carbon nanofilaments-platelets (CNF-PL) have high electrical conductivity and may be considered for fuel cells. In particular Pt and RuSe{sub x}, deposited on CNF-PL materials could act as efficient catalysts in fuel cells. This study used the RRDE to evaluate the oxygen reduction kinetics of these catalysts in oxygen-saturated, diluted sulphuric acid at room temperature. Kinetic data and hydrogen peroxide formation were determined by depositing a thin-film of the catalyst on the Au disc. The values for the constants k1, k2 and k3 were obtained using diagnostic criteria and expressions to calculate the rate constants of the cathodic oxygen reduction reaction for RuSe on new carbon supports. A potential dependency of the constants k1 and k2 for RuSe{sub x}/CNF-PL was observed. The transition of the Tafel slopes for this catalyst was obtained. 4 refs., 1 fig.

  14. Fluxes and exchange rates of radon and oxygen across an air-sea interface

    International Nuclear Information System (INIS)

    Duenas, C.; Fernandez, M.C.; La Torre, M. de

    1986-01-01

    The flux of 222 Rn and O 2 from shallow water off the Bay of Malaga has been measured. The mean value of flux of 222 Rn is evaluated to be 74 atoms/m 2 · s. The Bay is a weak source of oxygen to the atmosphere, where the net production of oxygen is found to be 1.82 mol/m 2 · y. Moreover, the gas exchange rates of 222 Rn and O 2 across the air-sea interface has been determined by the radon method. The gas exchange rates and the wind speed have been estimated. (author)

  15. Production of an accelerated oxygen-14 beam

    International Nuclear Information System (INIS)

    Powell, J.; O'Neil, J.P.; Cerny, Joseph

    2003-01-01

    BEARS is an ongoing project to provide a light-ion radioactive-beam capability at the 88-Inch Cyclotron at LBNL. Light radioactive isotopes are produced at a 10 MeV proton medical cyclotron, transported 350 m via a high-speed gas transport capillary, cryogenically separated, and injected into the 88-Inch Cyclotron's ion source. The first radioactive beam successfully accelerated was carbon-11 and beams of intensity more than 10 8 ions/s have been utilized for experiments. Development of oxygen-14 as the second BEARS beam presented considerable technical challenges, both due to its short half-life of 71 s and the radiation chemistry of oxygen in the target. The usual techniques developed for medical uses of oxygen-15 involve the addition of significant amounts of carrier oxygen, something that would overload the ion source. As a solution, oxygen-14 is produced as water in a carrier-free form, and is chemically converted in two steps to carbon dioxide, a form readily usable by the BEARS. This system has been built and is operational, and initial tests of accelerating an oxygen-14 beam have been performed

  16. Production of an accelerated oxygen-14 beam

    CERN Document Server

    Powell, J; Cerny, J

    2003-01-01

    BEARS is an ongoing project to provide a light-ion radioactive-beam capability at the 88-Inch Cyclotron at LBNL. Light radioactive isotopes are produced at a 10 MeV proton medical cyclotron, transported 350 m via a high-speed gas transport capillary, cryogenically separated, and injected into the 88-Inch Cyclotron's ion source. The first radioactive beam successfully accelerated was carbon-11 and beams of intensity more than 10 sup 8 ions/s have been utilized for experiments. Development of oxygen-14 as the second BEARS beam presented considerable technical challenges, both due to its short half-life of 71 s and the radiation chemistry of oxygen in the target. The usual techniques developed for medical uses of oxygen-15 involve the addition of significant amounts of carrier oxygen, something that would overload the ion source. As a solution, oxygen-14 is produced as water in a carrier-free form, and is chemically converted in two steps to carbon dioxide, a form readily usable by the BEARS. This system has bee...

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

    Science.gov (United States)

    Arbib, Zouhayr; de Godos Crespo, Ignacio; Corona, Enrique Lara; Rogalla, Frank

    2017-06-01

    Microalgae culture in high rate algae ponds (HRAP) is an environmentally friendly technology for wastewater treatment. However, for the implementation of these systems, a better understanding of the oxygenation potential and the influence of climate conditions is required. In this work, the rates of oxygen production, consumption, and exchange with the atmosphere were calculated under varying conditions of solar irradiance and dilution rate during six months of operation in a real scale unit. This analysis allowed determining the biological response of these dynamic systems. The rates of oxygen consumption measured were considerably higher than the values calculated based on the organic loading rate. The response to light intensity in terms of oxygen production in the bioreactor was described with one of the models proposed for microalgae culture in dense concentrations. This model is based on the availability of light inside the culture and the specific response of microalgae to this parameter. The specific response to solar radiation intensity showed a reasonable stability in spite of the fluctuations due to meteorological conditions. The methodology developed is a useful tool for optimization and prediction of the performance of these systems.

  18. Hydrogen peroxide production is affected by oxygen levels in mammalian cell culture.

    Science.gov (United States)

    Maddalena, Lucas A; Selim, Shehab M; Fonseca, Joao; Messner, Holt; McGowan, Shannon; Stuart, Jeffrey A

    2017-11-04

    Although oxygen levels in the extracellular space of most mammalian tissues are just a few percent, under standard cell culture conditions they are not regulated and are often substantially higher. Some cellular sources of reactive oxygen species, like NADPH oxidase 4, are sensitive to oxygen levels in the range between 'normal' physiological (typically 1-5%) and standard cell culture (up to 18%). Hydrogen peroxide in particular participates in signal transduction pathways via protein redox modifications, so the potential increase in its production under standard cell culture conditions is important to understand. We measured the rates of cellular hydrogen peroxide production in some common cell lines, including C2C12, PC-3, HeLa, SH-SY5Y, MCF-7, and mouse embryonic fibroblasts (MEFs) maintained at 18% or 5% oxygen. In all instances the rate of hydrogen peroxide production by these cells was significantly greater at 18% oxygen than at 5%. The increase in hydrogen peroxide production at higher oxygen levels was either abolished or substantially reduced by treatment with GKT 137831, a selective inhibitor of NADPH oxidase subunits 1 and 4. These data indicate that oxygen levels experienced by cells in culture influence hydrogen peroxide production via NADPH oxidase 1/4, highlighting the importance of regulating oxygen levels in culture near physiological values. However, we measured pericellular oxygen levels adjacent to cell monolayers under a variety of conditions and with different cell lines and found that, particularly when growing at 5% incubator oxygen levels, pericellular oxygen was often lower and variable. Together, these observations indicate the importance, and difficulty, of regulating oxygen levels experienced by cells in culture. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Effect of static magnetic field on the oxygen production of Scenedesmus obliquus cultivated in municipal wastewater.

    Science.gov (United States)

    Tu, Renjie; Jin, Wenbiao; Xi, Tingting; Yang, Qian; Han, Song-Fang; Abomohra, Abd El-Fatah

    2015-12-01

    Algal-bacterial symbiotic system, with biological synergism of physiological functions of both algae and bacteria, has been proposed for cultivation of microalgae in municipal wastewater for biomass production and wastewater treatment. The algal-bacterial symbiotic system can enhance dissolved oxygen production which enhances bacterial growth and catabolism of pollutants in wastewater. Therefore, the oxygen production efficiency of microalgae in algal-bacterial systems is considered as the key factor influencing the wastewater treatment efficiency. In the present study, we have proposed a novel approach which uses static magnetic field to enhance algal growth and oxygen production rate with low operational cost and non-toxic secondary pollution. The performance of oxygen production with the magnetic field was evaluated using Scenedesmus obliquus grown in municipal wastewater and was calculated based on the change in dissolved oxygen concentration. Results indicated that magnetic treatment stimulates both algal growth and oxygen production. Application of 1000 GS of magnetic field once at logarithmic growth phase for 0.5 h increased the chlorophyll-a content by 11.5% over the control after 6 days of growth. In addition, magnetization enhanced the oxygen production rate by 24.6% over the control. Results of the study confirmed that application of a proper magnetic field could reduce the energy consumption required for aeration during the degradation of organic matter in municipal wastewater in algal-bacterial symbiotic systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. 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...

  1. Non-self-sustained electric discharge in oxygen gas mixtures: singlet delta oxygen production

    CERN Document Server

    Ionin, A A; Kotkov, A A; Kochetov, I V; Napartovich, A P; Seleznev, L V; Sinitsyn, D V; Hager, G D

    2003-01-01

    The possibility of obtaining a high specific input energy in an electron-beam sustained discharge ignited in oxygen gas mixtures O sub 2 : Ar : CO (or H sub 2) at the total gas pressures of 10-100 Torr was experimentally demonstrated. The specific input energy per molecular component exceeded approx 6 kJ l sup - sup 1 atm sup - sup 1 (150 kJ mol sup - sup 1) as a small amount of carbon monoxide was added into a gas mixture of oxygen and argon. It was theoretically demonstrated that one might expect to obtain a singlet delta oxygen yield of 25% exceeding its threshold value needed for an oxygen-iodine laser operation at room temperature, when maintaining a non-self-sustained discharge in oxygen gas mixtures with molecular additives CO, H sub 2 or D sub 2. The efficiency of singlet delta oxygen production can be as high as 40%.

  2. Determination of Oxygen Production by Cyanobacteria in Desert Environment Soil

    Science.gov (United States)

    Bueno Prieto, J. E.

    2009-12-01

    The cyanobacteria have been characterized for being precursor in the production of oxygen. By means of photosynthetic reactions, they provide oxygen to the environment that surrounds them and they capture part of surrounding dioxide of carbon. This way it happened since the primitive Earth until today. Besides, these microorganisms can support the harmful effects of ultraviolet radiation. The presence of cyanobacterias in an environment like a dry tropical bioma, such as the geographical location called Desert of The Tatacoa (Huila - Colombia), is determinant to establish parameters in the search of biological origin of atmospheric oxygen detected in Mars. In that case, I work with a random sample of not rhizospheric soil, taken to 15 cm of depth. After determining the presence of cyanobacterias in the sample, this one was in laboratory to stimulate the oxygen production. The presence of oxygen in Mars is very interesting. Since oxygen gas is very reactive, it disappear if it is not renewed; the possibility that this renovation of oxygen has a biological origin is encouraging, bearing in mind that in a dry environment and high radiation such as the studied one, the production of oxygen by cyanobacterias is notable. Also it is necessary to keep in mind that the existence of cyanobacterias would determine water presence in Mars subsoil and the nutrients cycles renovation. An interesting exploration possibility for some future space probe to Mars might be the study of worldwide distribution of oxygen concentration in this planet and this way, indentify zones suitable for microbian life.

  3. NPP ATMS Snowfall Rate Product

    Science.gov (United States)

    Meng, Huan; Ferraro, Ralph; Kongoli, Cezar; Wang, Nai-Yu; Dong, Jun; Zavodsky, Bradley; Yan, Banghua

    2015-01-01

    Passive microwave measurements at certain high frequencies are sensitive to the scattering effect of snow particles and can be utilized to retrieve snowfall properties. Some of the microwave sensors with snowfall sensitive channels are Advanced Microwave Sounding Unit (AMSU), Microwave Humidity Sounder (MHS) and Advance Technology Microwave Sounder (ATMS). ATMS is the follow-on sensor to AMSU and MHS. Currently, an AMSU and MHS based land snowfall rate (SFR) product is running operationally at NOAA/NESDIS. Based on the AMSU/MHS SFR, an ATMS SFR algorithm has been developed recently. The algorithm performs retrieval in three steps: snowfall detection, retrieval of cloud properties, and estimation of snow particle terminal velocity and snowfall rate. The snowfall detection component utilizes principal component analysis and a logistic regression model. The model employs a combination of temperature and water vapor sounding channels to detect the scattering signal from falling snow and derive the probability of snowfall (Kongoli et al., 2015). In addition, a set of NWP model based filters is also employed to improve the accuracy of snowfall detection. Cloud properties are retrieved using an inversion method with an iteration algorithm and a two-stream radiative transfer model (Yan et al., 2008). A method developed by Heymsfield and Westbrook (2010) is adopted to calculate snow particle terminal velocity. Finally, snowfall rate is computed by numerically solving a complex integral. NCEP CMORPH analysis has shown that integration of ATMS SFR has improved the performance of CMORPH-Snow. The ATMS SFR product is also being assessed at several NWS Weather Forecast Offices for its usefulness in weather forecast.

  4. Response of Microbial Soil Carbon Mineralization Rates to Oxygen Limitations

    Science.gov (United States)

    Keiluweit, M.; Denney, A.; Nico, P. S.; Fendorf, S. E.

    2014-12-01

    The rate of soil organic matter (SOM) mineralization is known to be controlled by climatic factors as well as molecular structure, mineral-organic associations, and physical protection. What remains elusive is to what extent oxygen (O2) limitations impact overall rates of microbial SOM mineralization (oxidation) in soils. Even within upland soils that are aerobic in bulk, factors limiting O2 diffusion such as texture and soil moisture can result in an abundance of anaerobic microsites in the interior of soil aggregates. Variation in ensuing anaerobic respiration pathways can further impact SOM mineralization rates. Using a combination of (first) aggregate model systems and (second) manipulations of intact field samples, we show how limitations on diffusion and carbon bioavailability interact to impose anaerobic conditions and associated respiration constraints on SOM mineralization rates. In model aggregates, we examined how particle size (soil texture) and amount of dissolved organic carbon (bioavailable carbon) affect O2 availability and distribution. Monitoring electron acceptor profiles (O2, NO3-, Mn and Fe) and SOM transformations (dissolved, particulate, mineral-associated pools) across the resulting redox gradients, we then determined the distribution of operative microbial metabolisms and their cumulative impact on SOM mineralization rates. Our results show that anaerobic conditions decrease SOM mineralization rates overall, but those are partially offset by the concurrent increases in SOM bioavailability due to transformations of protective mineral phases. In intact soil aggregates collected from soils varying in texture and SOM content, we mapped the spatial distribution of anaerobic microsites. Optode imaging, microsensor profiling and 3D tomography revealed that soil texture regulates overall O2 availability in aggregate interiors, while particulate SOM in biopores appears to control the fine-scale distribution of anaerobic microsites. Collectively, our

  5. Improvement of lipase production at different stirring speeds and oxygen levels

    Directory of Open Access Journals (Sweden)

    F.O.M. Alonso

    2005-03-01

    Full Text Available Lipase production by a Brazilian wild strain of Yarrowia lipolytica at different stirring speeds and air flow rates was studied. The relationship among lipid consumption, cell growth and lipase production by this microorganism is presented. The most pronounced effect of oxygen on lipase production was determined by stirring speed. Maximum lipase activity was detected in the late stationary phase at 200 rpm and an air flow rate of 1-2 dm³/min (0.8-1.7 vvm when the lipid source had been fully consumed. Higher stirring speeds resulted in mechanical and/or oxidative stress, while lower stirring speeds seemed to limit oxygen levels. An increase in the availability of oxygen at higher air flow rates led to faster lipid uptake and anticipation of enzyme release into the culture medium. The highest lipase production was obtained at 200 rpm and 1 dm³/min (0.8 vvm.

  6. Hyperbaric Oxygen Therapy and Oxygen Compatibility of Skin and Wound Care Products.

    Science.gov (United States)

    Bernatchez, Stéphanie F; Tucker, Joseph; Chiffoleau, Gwenael

    2017-11-01

    Objective: Use test methods to assess the oxygen compatibility of various wound care products. Approach: There are currently no standard test methods specifically for evaluating the oxygen compatibility and safety of materials under hyperbaric oxygen (HBO) conditions. However, tests such as the oxygen index (OI), oxygen exposure (OE), and autogenous ignition temperature (AIT) can provide useful information. Results: The OI test measures the minimum oxygen concentration that will support candle-like burning, and it was used to test 44 materials. All but two exhibited an OI equal to or greater (safer) than a control material commonly used in HBO. The OE test exposes each material to an oxygen-enriched atmosphere (>99.5% oxygen) to monitor temperature and pressure for an extended duration. The results of the OE testing indicated that none of the 44 articles tested with this method self-ignited within the 60°C, 3 atm pressurized oxygen atmosphere. The AIT test exposes materials to a rapid ramp up in temperature in HBO conditions at 3 atm until ignition occurs. Ten wound care materials and seven materials usually avoided in HBO chambers were tested. The AIT ranged from 138°C to 384°C for wound care products and from 146°C to 420°C for the other materials. Innovation: This work provides useful data and recommendations to help develop a new standard approach for evaluating the HBO compatibility of wound care products to ensure safety for patients and clinicians. Conclusion: The development of an additional test to measure the risk of electrostatic discharge of materials in HBO conditions is needed.

  7. Production and use of metals and oxygen for lunar propulsion

    Science.gov (United States)

    Hepp, Aloysius F.; Linne, Diane L.; Groth, Mary F.; Landis, Geoffrey A.; Colvin, James E.

    1991-01-01

    Production, power, and propulsion technologies for using oxygen and metals derived from lunar resources are discussed. The production process is described, and several of the more developed processes are discussed. Power requirements for chemical, thermal, and electrical production methods are compared. The discussion includes potential impact of ongoing power technology programs on lunar production requirements. The performance potential of several possible metal fuels including aluminum, silicon, iron, and titanium are compared. Space propulsion technology in the area of metal/oxygen rocket engines is discussed.

  8. Hydrogen and oxygen production with nuclear heat

    International Nuclear Information System (INIS)

    Barnert, H.

    1979-09-01

    After some remarks on the necessity of producing secondary energy sources for the heat market, the thermodynamic fundamentals of the processes for producing hydrogen and oxygen from water on the basis of nuclear thermal energy are briefly explained. These processes are summarized as one class of the 'thermochemical cycle process' for the conversion of thermal into chemical energy. A number of thermochemical cycle processes are described. The results of the design work so far are illustrated by the example of the 'sulphuric acid hybrid process'. The nuclear heat source of the thermochemical cycle process is the high-temperature reactor. Statements concerning rentability are briefly commented upon, and the research and development efforts and expenditure required are sketched. (orig.) 891 GG/orig. 892 MB [de

  9. Singlet oxygen production and quenching mechanisms in travelling microwave discharges

    International Nuclear Information System (INIS)

    Savin, Yu V; Goryachev, L V; Adamenkov, Yu A; Rakhimova, T V; Mankelevich, Yu A; Popov, N A; Adamenkov, A A; Egorov, V V; Ilyin, S P; Kolobyanin, Yu V; Kudryashov, E A; Rogozhnikov, G S; Vyskubenko, B A

    2004-01-01

    Experimental and theoretical studies of singlet oxygen excitation in travelling microwave (TMW) discharges are presented. Singlet oxygen O 2 (a 1 Δ g ) concentrations and atomic oxygen mole fraction have been measured for different pressures, input powers and distances from the MW resonator. It was shown that a steady-state TMW discharge with a coaxial cavity resonator could provide a maximal O 2 (a 1 Δ g ) yield of 22% for 2 Torr of pure oxygen and 27-30% for He : O 2 = 1 : 1 mixture. The two-dimensional (r, z) model developed for calculations of plasma-chemical kinetics, heat and mass transfer was used for simulation of processes in the TMW discharge under study. Effects of gas pressure, gas flow rate and input power are studied and compared with experimental measurements of O 2 (a 1 Δ g ) concentrations and atomic oxygen mole fractions

  10. In situ measurement of the rate of oxygen consumption by the Callovo-Oxfordian argillaceous rock

    International Nuclear Information System (INIS)

    Vinsot, A.; Lundy, M.; Claret, F.; Wechner, S.

    2012-01-01

    fluid to protect the rock from any contact with air. The borehole equipment was installed just after the drilling and isolated the test interval with a packer. The equipment includes several lines, which link the test interval to the drift, and make it possible to circulate gas and collect the pore water flowing from the rock into the test interval. In the drift, a gas circulation module allows to circulate the gas and to monitor its composition. This module includes a circulation pump, an oxygen specific probe and cylinders which can be disconnected for gas sample analyses. In addition, the gas circulation module makes possible the injection of pure oxygen at a controlled flow rate. Another module is dedicated to water extraction at a controlled flow rate and permits water composition monitoring. Before the first oxygen injection, a stable water production flow rate between 30 and 40 mL/day was obtained in the borehole. This flow rate indicates that the test interval wall is presumably saturated with water. The water composition is similar to those previously obtained in the URL. The first oxygen injection was performed by replacing the previous circulating gas by a mixture of gases containing 14% O 2 , 5% He, 5% Ne and 76% Ar at a total pressure close to 1.5 bars. As a result the oxygen partial pressure was close to 0.2 bars just after the gas replacement. Helium and neon served as reference non-reactive gases: the evolution of their content should only depend on the dissolution and diffusion processes in the rock pore water. As a consequence, they will help to calibrate the transport part in a reactive transport model. Following its first injection in the test interval, oxygen totally disappeared in the time frame of less than three days. No immediate effect on the extracted water composition was observed. In October 2011, pure oxygen was added three times to the circulating gas to reach each time more an oxygen partial pressure of 0.2 bars in the test interval

  11. Oxygen transfer rate identifies priming compounds in parsley cells.

    Science.gov (United States)

    Schilling, Jana Viola; Schillheim, Britta; Mahr, Stefan; Reufer, Yannik; Sanjoyo, Sandi; Conrath, Uwe; Büchs, Jochen

    2015-11-25

    In modern agriculture, the call for an alternative crop protection strategy increases because of the desired reduction of fungicide and pesticide use and the continuously evolving resistance of pathogens and pests to agrochemicals. The direct activation of the plant immune system does not provide a promising plant protection measure because of high fitness costs. However, upon treatment with certain natural or synthetic compounds, plant cells can promote to a fitness cost-saving, primed state of enhanced defense. In the primed state, plants respond to biotic and abiotic stress with faster and stronger activation of defense, and this is often associated with immunity and abiotic stress tolerance. Until now, the identification of chemical compounds with priming-inducing activity (so-called plant activators) relied on tedious and invasive approaches, or required the late detection of secreted furanocoumarin phytoalexins in parsley cell cultures. Thus, simple, fast, straightforward, and noninvasive techniques for identifying priming-inducing compounds for plant protection are very welcome. This report demonstrates that a respiration activity-monitoring system (RAMOS) can identify compounds with defense priming-inducing activity in parsley cell suspension in culture. RAMOS relies on the quasi-continuous, noninvasive online determination of the oxygen transfer rate (OTR). Treatment of parsley culture cells with the known plant activator salicylic acid (SA), a natural plant defense signal, resulted in an OTR increase. Addition of the defense elicitor Pep13, a cell wall peptide of Phythophthora sojae, induced two distinctive OTR peaks that were higher in SA-primed cells than in unprimed cells upon Pep13 challenge. Both, the OTR increase after priming with SA and the Pep13 challenge were dose-dependent. Furthermore, there was a close correlation of a compound's activity to enhance the oxygen consumption in parsley cells and its capacity to prime Pep13-induced furanocoumarin

  12. 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.

  13. Effects of oxygen supply on the biodegradation rate in oil hydrocarbons contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Zawierucha, I [Institute of Chemistry and Environment Protection, Jan Dlugosz University of Czestochowa, Waszyngtona 4/8, 42-200 Czestochowa (Poland); Malina, G, E-mail: iwona_zawierucha@o2.pl [Faculty of Hydrogeology and Geology Engineering, Department of Geology, Geophysics and Environment Protection, AGH University of Science and Technology, Mickiewicza 30, 30-059 Cracow (Poland)

    2011-04-01

    Respirometry studies using the 10-chamber Micro-Oxymax respirometer (Columbus, Ohio) were conducted to determine the effect of biostimulation (by diverse ways of O{sub 2} supply) on enhancing biodegradation in soils contaminated with oil hydrocarbons. Soil was collected from a former military airport in Kluczewo, Poland. Oxygen was supplied by means of aerated water, aqueous solutions of H{sub 2}O{sub 2} and KMnO{sub 4}. The biodegradation was evaluated on the basis of O{sub 2} uptake and CO{sub 2} production. The O{sub 2} consumption and CO{sub 2} production rates during hydrocarbons biodegradation were estimated from the slopes of cumulative curve linear regressions. The pertinent intrinsic and enhanced biodegradation rates were calculated on the basis of mass balance equation and O{sub 2} uptake and CO{sub 2} production rates. The biodegradation rates of 5-7 times higher as compared to a control were observed when the aqueous solution of KMnO{sub 4} in concentration of 20 g L{sup -1} was applied. Permanganate is known to readily oxidize alkene carbon - carbon double bonds; so it can be successfully applied in remediation technology for soils contaminated with oil hydrocarbons. While hydrocarbons are not completely mineralized by permanganate oxidation reactions, their structure is altered by polar functional groups providing vast improvements in aqueous solubility and availability for biodegradation. The 3% aqueous solution of H{sub 2}O{sub 2} caused significant improvement of the biodegradation rates as compared to a control (on average about 260%). Aerobic biodegradation of hydrocarbons can benefit from the presence of oxygen released during H{sub 2}O{sub 2} decomposition. Adding of aerated water resulted in an increase of biodegradation rates (about 114 - 229%) as compared to a control. The aerated water can both be the source of oxygen for microorganisms and determine the transport of substrate to bacteria cells.

  14. Atomic oxygen production scaling in a nanosecond-pulsed externally grounded dielectric barrier plasma jet

    Science.gov (United States)

    Sands, Brian; Schmidt, Jacob; Ganguly, Biswa; Scofield, James

    2014-10-01

    Atomic oxygen production is studied in a capillary dielectric barrier plasma jet that is externally grounded and driven with a 20-ns risetime positive unipolar pulsed voltage at pulse repetition rates up to 25 kHz. The power coupled to the discharge can be easily increased by increasing the pulse repetition rate. At a critical turnover frequency, determined by the net energy density coupled to the discharge, the plasma chemistry abruptly changes. This is indicated by increased plasma conductance and a transition in reactive oxygen species production from an ozone-dominated production regime below the turnover frequency to atomic-oxygen-dominated production at higher pulse rates. Here, we characterize atomic oxygen production scaling using spatially- and temporally-resolved two-photon absorption laser-induced-fluorescence (TALIF). Quantitative results are obtained via calibration with xenon using a similar laser excitation and collection system. These results are compared with quantitative ozone and discharge power measurements using a helium gas flow with oxygen admixtures up to 3%.

  15. Effects of oxygen and catalyst on tetraphenylborate decomposition rate

    International Nuclear Information System (INIS)

    Walker, D.D.

    1999-01-01

    Previous studies indicate that palladium catalyzes rapid decomposition of alkaline tetraphenylborate slurries. Oxygen inhibits the reaction at low temperature (25 C), presumably by preventing activation of the catalyst. The present study investigated oxygen's inhibiting effectiveness at higher temperature (45 C) and catalyst concentrations

  16. Release of intracellular Calcium increase production of mitochondrial reactive oxygen species in renal distal epithelial cells

    DEFF Research Database (Denmark)

    Bjerregaard, Henning F.

    peroxide (H2O2) has traditionally been regarded as toxic by-products of aerobic metabolism. However, recent findings indicate that H2O2 act as a signalling molecule. The aim of the present study was to monitor, in real time, the rates of ROS generation in order to directly determine their production......Release of intracellular Calcium increase production of mitochondrial reactive oxygen species in renal distal epithelial cells. Henning F. Bjerregaard, Roskilde University, Department of Science, Systems and Models , 4000 Roskilde, Denmark. HFB@ RUC.DK Reactive oxygen species (ROS) like, hydrogen...... to G-protein stimulation of phospholipase C and release of inositol -3 phosphate. Cd (0.4 mM) treatment of A6 cells enhanced the ROS production after one minutes incubation. The production rate was constant for at least 10 to 20 min. Experiments showed that the Cd induced increase in ROS production...

  17. 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.

  18. Quantifying salinity and season effects on eastern oyster clearance and oxygen consumption rates

    Science.gov (United States)

    Casas, S.M.; Lavaud, Romain; LaPeyre, Megan K.; Comeau, L. A.; Filgueira, R.; LaPeyre, Jerome F.

    2018-01-01

    There are few data on Crassostrea virginica physiological rates across the range of salinities and temperatures to which they are regularly exposed, and this limits the applicability of growth and production models using these data. The objectives of this study were to quantify, in winter (17 °C) and summer (27 °C), the clearance and oxygen consumption rates of C. virginica from Louisiana across a range of salinities typical of the region (3, 6, 9, 15 and 25). Salinity and season (temperature and reproduction) affected C. virginica physiology differently; salinity impacted clearance rates with reduced feeding rates at low salinities, while season had a strong effect on respiration rates. Highest clearance rates were found at salinities of 9–25, with reductions ranging from 50 to 80 and 90 to 95% at salinities of 6 and 3, respectively. Oxygen consumption rates in summer were four times higher than in winter. Oxygen consumption rates were within a narrow range and similar among salinities in winter, but varied greatly among individuals and salinities in summer. This likely reflected varying stages of gonad development. Valve movements measured at the five salinities indicated oysters were open 50–60% of the time in the 6–25 salinity range and ~ 30% at a salinity of 3. Reduced opening periods, concomitant with narrower valve gap amplitudes, are in accord with the limited feeding at the lowest salinity (3). These data indicate the need for increased focus on experimental determination of optimal ranges and thresholds to better quantify oyster population responses to environmental changes.

  19. 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.

  20. Late Quaternary changes in surface productivity and oxygen ...

    Indian Academy of Sciences (India)

    Changes in the abundance of selected planktic foraminiferal species and some sedimentological parameters at ODP site 728A were examined to understand the fluctuations in the surface productivity and deep sea oxygenation in the NW Arabian Sea during last ∼540 kyr. The increased relative abundances of high fertility ...

  1. Changes in carbon storage and oxygen production in forest timber ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-05

    Oct 5, 2009 ... treaties and processes, has shown itself around the world and in our country as the concept of planning and ... Key words: Carbon storage, oxygen production, forest management, geographic information systems, land cover change. .... biomass transformation factors developed for the forests in Turkey are ...

  2. [Design of Oxygen Saturation, Heart Rate, Respiration Rate Detection System Based on Smartphone of Android Operating System].

    Science.gov (United States)

    Zhu, Mingshan; Zeng, Bixin

    2015-03-01

    In this paper, we designed an oxygen saturation, heart rate, respiration rate monitoring system based on smartphone of android operating system, physiological signal acquired by MSP430 microcontroller and transmitted by Bluetooth module.

  3. Photosynthetic oxygen production in a warmer ocean: the Sargasso Sea as a case study.

    Science.gov (United States)

    Richardson, Katherine; Bendtsen, Jørgen

    2017-09-13

    Photosynthetic O 2 production can be an important source of oxygen in sub-surface ocean waters especially in permanently stratified oligotrophic regions of the ocean where O 2 produced in deep chlorophyll maxima (DCM) is not likely to be outgassed. Today, permanently stratified regions extend across approximately 40% of the global ocean and their extent is expected to increase in a warmer ocean. Thus, predicting future ocean oxygen conditions requires a better understanding of the potential response of photosynthetic oxygen production to a warmer ocean. Based on our own and published observations of water column processes in oligotrophic regions, we develop a one-dimensional water column model describing photosynthetic oxygen production in the Sargasso Sea to quantify the importance of photosynthesis for the downward flux of O 2 and examine how it may be influenced in a warmer ocean. Photosynthesis is driven in the model by vertical mixing of nutrients (including eddy-induced mixing) and diazotrophy and is found to substantially increase the downward O 2 flux relative to physical-chemical processes alone. Warming (2°C) surface waters does not significantly change oxygen production at the DCM. Nor does a 15% increase in re-mineralization rate (assuming Q 10  = 2; 2°C warming) have significant effect on net sub-surface oxygen accumulation. However, changes in the relative production of particulate (POM) and dissolved organic material (DOM) generate relatively large changes in net sub-surface oxygen production. As POM/DOM production is a function of plankton community composition, this implies plankton biodiversity and food web structure may be important factors influencing O 2 production in a warmer ocean.This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'. © 2017 The Author(s).

  4. Determination of in vitro oxygen consumption rates for tumor cells

    International Nuclear Information System (INIS)

    Cardenas-Navia, L.I.; Moeller, B.J.; Kirkpatrick, J.P.; Laursen, T.A.; Dewhirst, M.W.

    2003-01-01

    To determine pO 2 at the surface of a monolayer of confluent HCT 116 cells, and to then determine consumption rate in vitro by examining the pO 2 profile in media above the cells. Materials and Methods: A recessed-tip polarographic oxygen microelectrode (diameter ∼10μm) was used to measure pO 2 profiles of media above a confluent monolayer of HCT 116 human colon adenocarcinoma cells in a T25 flask exposed to a 95% air, 5% CO 2 mixture. A two-dimensional finite element analysis of the diffusion equation was used to fit the data, thereby extracting a steady-state O 2 consumption rate. The diffusion equation was solved for zeroth and first-order expressions. No-flux boundary conditions were imposed on its bottom and side boundaries and experimental data was used for boundary conditions at the gas-media boundary. All flasks show an O 2 gradient in the media, with a mean (SE) media layer of 1677 (147) μm and a mean pO 2 at the cell layer/media interface of 44 (8) mm Hg (n=9). pO 2 gradient over the entire media layer is 630 (90) mm Hg/cm, equivalent to a consumption rate of 6.3 x 10 -4 (9.0 x 10 -5 ) mm Hg/s. The mean values for the zeroth and first order rate constants are 8.1 x 10 -9 (1.3 x 10 -9 ) g mol O 2 /cm 3 s and 1.0 x 10 3 (0.46 x 10 3 ) /s, respectively. Control experiments in flasks containing no cells show slight gradients in pO 2 of 38 (12) mm Hg/cm, resulting from some O 2 diffusion through the flask into the surrounding water bath. An addition of 10 -3 M NaCN to the media results in a dramatic increase in pO 2 at the cell layer, consistent with a shut-down in respiration. Under normal cell culture conditions there is an O 2 gradient present in the media of cull culture systems, resulting in physiologic O 2 concentrations at the cell layer, despite the non-physiologic O 2 concentration of the gas mixture to which the cell culture system is exposed. This significant (p -6 ) O 2 gradient in the media of cell culture systems is a result of cell O 2

  5. Heart Rate and Oxygen Uptake Recovery and the Level of Aerobic Capacity in Mountain Bikers

    Directory of Open Access Journals (Sweden)

    Michalik Kamil

    2017-12-01

    Full Text Available Introduction. Since mountain biking involves exercise of varying intensity, competitive performance may be affected by the rate of recovery. The aim of the current study was to determine whether maximal oxygen uptake is associated with the rate of heart rate and oxygen uptake recovery in mountain bike athletes.

  6. The economic production lot size model with several production rates

    DEFF Research Database (Denmark)

    Larsen, Christian

    should be chosen in the interval between the demand rate and the production rate, which minimize unit production costs, and should be used in an increasing order. Then, given the production rates, we derive closed form solutions for the optimal runtimes as well as the minimum average cost. Finally we...

  7. Atmospheric production rate of {sup 36}Cl

    Energy Technology Data Exchange (ETDEWEB)

    Parrat, Y.; Hajdas, W.; Baltensperger, U.; Synal, H.A.; Kubik, P.W.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Suter, M. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    Using experimental cross sections, a new calculation of the atmospheric production rate of {sup 36}Cl was carried out. A mean production rate of 20 atoms m{sup -2}s{sup -1} was obtained, which is lower than mean {sup 36}Cl deposition rates. (author) 2 figs., 7 refs.

  8. Atmospheric production rate of 36Cl

    International Nuclear Information System (INIS)

    Parrat, Y.; Hajdas, W.; Baltensperger, U.; Synal, H.A.; Kubik, P.W.; Gaeggeler, H.W.; Suter, M.

    1997-01-01

    Using experimental cross sections, a new calculation of the atmospheric production rate of 36 Cl was carried out. A mean production rate of 20 atoms m -2 s -1 was obtained, which is lower than mean 36 Cl deposition rates. (author) 2 figs., 7 refs

  9. Rates of oxygen uptake increase independently of changes in heart rate in late stages of development and at hatching in the green iguana, Iguana iguana.

    Science.gov (United States)

    Sartori, Marina R; Abe, Augusto S; Crossley, Dane A; Taylor, Edwin W

    2017-03-01

    Oxygen consumption (VO 2 ), heart rate (f H ), heart mass (M h ) and body mass (M b ) were measured during embryonic incubation and in hatchlings of green iguana (Iguana iguana). Mean f H and VO 2 were unvarying in early stage embryos. VO 2 increased exponentially during the later stages of embryonic development, doubling by the end of incubation, while f H was constant, resulting in a 2.7-fold increase in oxygen pulse. Compared to late stage embryos, the mean inactive level of VO 2 in hatchlings was 1.7 fold higher, while f H was reduced by half resulting in a further 3.6 fold increase in oxygen pulse. There was an overall negative correlation between mean f H and VO 2 when data from hatchlings was included. Thus, predicting metabolic rate as VO 2 from measurements of f H is not possible in embryonic reptiles. Convective transport of oxygen to supply metabolism during embryonic incubation was more reliably indicated as an index of cardiac output (CO i ) derived from the product of f H and M h . However, a thorough analysis of factors determining rates of oxygen supply during development and eclosion in reptiles will require cannulation of blood vessels that proved impossible in the present study, to determine oxygen carrying capacity by the blood and arteriovenous oxygen content difference (A-V diff), plus patterns of blood flow. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. NESDIS Blended Rain Rate (RR) Products

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The blended Rain Rate (RR) product is derived from multiple sensors/satellites. The blended products were merged from polar-orbiting and geostationary satellite...

  11. Seasonal Oxygen Dynamics in a Thermokarst Bog in Interior Alaska: Implications for Rates of Methane Oxidation

    Science.gov (United States)

    Neumann, R. B.; Moorberg, C.; Wong, A.; Waldrop, M. P.; Turetsky, M. R.

    2015-12-01

    Methane is a potent greenhouse gas, and wetlands represent the largest natural source of methane to the atmosphere. However, much of the methane generated in anoxic wetlands never gets emitted to the atmosphere; up to >90% of generated methane can get oxidized to carbon dioxide. Thus, oxidation is an important methane sink and changes in the rate of methane oxidation can affect wetland methane emissions. Most methane is aerobically oxidized at oxic-anoxic interfaces where rates of oxidation strongly depend on methane and oxygen concentrations. In wetlands, oxygen is often the limiting substrate. To improve understanding of belowground oxygen dynamics and its impact on methane oxidation, we deployed two planar optical oxygen sensors in a thermokarst bog in interior Alaska. Previous work at this site indicated that, similar to other sites, rates of methane oxidation decrease over the growing season. We used the sensors to track spatial and temporal patterns of oxygen concentrations over the growing season. We coupled these in-situ oxygen measurements with periodic oxygen injection experiments performed against the sensor to quantify belowground rates of oxygen consumption. We found that over the season, the thickness of the oxygenated water layer at the peatland surface decreased. Previous research has indicated that in sphagnum-dominated peatlands, like the one studied here, rates of methane oxidation are highest at or slightly below the water table. It is in these saturated but oxygenated locations that both methane and oxygen are available. Thus, a seasonal reduction in the thickness of the oxygenated water layer could restrict methane oxidation. The decrease in thickness of the oxygenated layer coincided with an increase in the rate of oxygen consumption during our oxygen injection experiments. The increase in oxygen consumption was not explained by temperature; we infer it was due to an increase in substrate availability for oxygen consuming reactions and

  12. Oxygen transfer rates and requirements in oxidative biocatalysis

    DEFF Research Database (Denmark)

    Pedersen, Asbjørn Toftgaard; Rehn, Gustav; Woodley, John

    2015-01-01

    Biocatalytic oxidation reactions offer several important benefits such as regio- and stereoselectivity, avoiding the use of toxic metal based catalysts and replacing oxidizing reagents by allowing the use of oxygen. However, the development of biocatalytic oxidation processes is a complex task......-up is relatively straight forward (Gabelman and Hwang, 1999), and membrane contactors are implemented for various industrial applications (Klaassen et al., 2005)....

  13. Oxygen production processes on the Moon: An overview

    Science.gov (United States)

    Taylor, Lawrence A.; Carrier, W. David, III

    1991-01-01

    The production of oxygen on the Moon utilizing indigenous material is paramount to a successful lunar colonization. Several processes were put forth to accomplish this. The lunar liquid oxygen (LLOX) generation schemes which have received the most study to date are those involving: (1) the reduction of ilmenite (FeTiO3) by H2, C, CO, CH4, CO-Cl2 plasma; (2) magma electrolysis, both unadulterated and fluoride-fluxed, and (3) several others, including carbo-chlorination, HF acid leaching, fluorine extraction, magma oxidation, and vapor pyrolysis. The H2 reduction of ilmenite and magma electrolysis processes have received the most study to date. At this stage of development, they both appear feasible schemes with various pros and cons. However, all processes should be addressed at least at the onset of the considerations. It is ultimatley the energy requirements of the entire process, including the acquisition of feedstock, which will determine the mode of oxygen productions. There is an obvious need for considerably more experimentation and study. Some of these requisite studies are in progress, and several of the most studied and feasible processes for winning oxygen from lunar materials are reviewed.

  14. Mapping {sup 15}O Production Rate for Proton Therapy Verification

    Energy Technology Data Exchange (ETDEWEB)

    Grogg, Kira; Alpert, Nathaniel M.; Zhu, Xuping [Center for Advanced Radiological Sciences, Nuclear Medicine and Molecular Imaging, Radiology Department, Massachusetts General Hospital, Boston, Massachusetts (United States); Min, Chul Hee [Department of Radiological Science, College of Health Science, Yonsei University, Wonju, Kangwon (Korea, Republic of); Testa, Mauro; Winey, Brian [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Normandin, Marc D. [Center for Advanced Radiological Sciences, Nuclear Medicine and Molecular Imaging, Radiology Department, Massachusetts General Hospital, Boston, Massachusetts (United States); Shih, Helen A.; Paganetti, Harald; Bortfeld, Thomas [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); El Fakhri, Georges, E-mail: elfakhri@pet.mgh.harvard.edu [Center for Advanced Radiological Sciences, Nuclear Medicine and Molecular Imaging, Radiology Department, Massachusetts General Hospital, Boston, Massachusetts (United States)

    2015-06-01

    Purpose: This work was a proof-of-principle study for the evaluation of oxygen-15 ({sup 15}O) production as an imaging target through the use of positron emission tomography (PET), to improve verification of proton treatment plans and to study the effects of perfusion. Methods and Materials: Dynamic PET measurements of irradiation-produced isotopes were made for a phantom and rabbit thigh muscles. The rabbit muscle was irradiated and imaged under both live and dead conditions. A differential equation was fitted to phantom and in vivo data, yielding estimates of {sup 15}O production and clearance rates, which were compared to live versus dead rates for the rabbit and to Monte Carlo predictions. Results: PET clearance rates agreed with decay constants of the dominant radionuclide species in 3 different phantom materials. In 2 oxygen-rich materials, the ratio of {sup 15}O production rates agreed with the expected ratio. In the dead rabbit thighs, the dynamic PET concentration histories were accurately described using {sup 15}O decay constant, whereas the live thigh activity decayed faster. Most importantly, the {sup 15}O production rates agreed within 2% (P>.5) between conditions. Conclusions: We developed a new method for quantitative measurement of {sup 15}O production and clearance rates in the period immediately following proton therapy. Measurements in the phantom and rabbits were well described in terms of {sup 15}O production and clearance rates, plus a correction for other isotopes. These proof-of-principle results support the feasibility of detailed verification of proton therapy treatment delivery. In addition, {sup 15}O clearance rates may be useful in monitoring permeability changes due to therapy.

  15. Comparison of specific oxygen uptake rates of two beach-scale ...

    African Journals Online (AJOL)

    The determined values of oxygen uptake rate during the endogenous reaction phase (between 0.1054 and 0.3564 mgO2/L.minute) and concentrations of mixed liquor suspended solids (between 1183 and 1957 mgMLSS/L) are comparable to those reported elsewhere in literature. Results of specific oxygen uptake rate of ...

  16. Microbial methane production in oxygenated water column of an oligotrophic lake

    Science.gov (United States)

    Grossart, Hans-Peter; Frindte, Katharina; Dziallas, Claudia; Eckert, Werner; Tang, Kam W.

    2011-01-01

    The prevailing paradigm in aquatic science is that microbial methanogenesis happens primarily in anoxic environments. Here, we used multiple complementary approaches to show that microbial methane production could and did occur in the well-oxygenated water column of an oligotrophic lake (Lake Stechlin, Germany). Oversaturation of methane was repeatedly recorded in the well-oxygenated upper 10 m of the water column, and the methane maxima coincided with oxygen oversaturation at 6 m. Laboratory incubations of unamended epilimnetic lake water and inoculations of photoautotrophs with a lake-enrichment culture both led to methane production even in the presence of oxygen, and the production was not affected by the addition of inorganic phosphate or methylated compounds. Methane production was also detected by in-lake incubations of lake water, and the highest production rate was 1.8–2.4 nM⋅h−1 at 6 m, which could explain 33–44% of the observed ambient methane accumulation in the same month. Temporal and spatial uncoupling between methanogenesis and methanotrophy was supported by field and laboratory measurements, which also helped explain the oversaturation of methane in the upper water column. Potentially methanogenic Archaea were detected in situ in the oxygenated, methane-rich epilimnion, and their attachment to photoautotrophs might allow for anaerobic growth and direct transfer of substrates for methane production. Specific PCR on mRNA of the methyl coenzyme M reductase A gene revealed active methanogenesis. Microbial methane production in oxygenated water represents a hitherto overlooked source of methane and can be important for carbon cycling in the aquatic environments and water to air methane flux. PMID:22089233

  17. Islet oxygen consumption rate (OCR) dose predicts insulin independence for first clinical islet allotransplants

    Science.gov (United States)

    Kitzmann, JP; O’Gorman, D; Kin, T; Gruessner, AC; Senior, P; Imes, S; Gruessner, RW; Shapiro, AMJ; Papas, KK

    2014-01-01

    Human islet allotransplant (ITx) for the treatment of type 1 diabetes is in phase III clinical registration trials in the US and standard of care in several other countries. Current islet product release criteria include viability based on cell membrane integrity stains, glucose stimulated insulin release (GSIR), and islet equivalent (IE) dose based on counts. However, only a fraction of patients transplanted with islets that meet or exceed these release criteria become insulin independent following one transplant. Measurements of islet oxygen consumption rate (OCR) have been reported as highly predictive of transplant outcome in many models. In this paper we report on the assessment of clinical islet allograft preparations using islet oxygen consumption rate (OCR) dose (or viable IE dose) and current product release assays in a series of 13 first transplant recipients. The predictive capability of each assay was examined and successful graft function was defined as 100% insulin independence within 45 days post-transplant. Results showed that OCR dose was most predictive of CTO. IE dose was also highly predictive, while GSIR and membrane integrity stains were not. In conclusion, OCR dose can predict CTO with high specificity and sensitivity and is a useful tool for evaluating islet preparations prior to clinical ITx. PMID:25131089

  18. Production of Singlet Oxygen in a Non-Self-Sustained Discharge

    International Nuclear Information System (INIS)

    Vasil'eva, A.N.; Klopovskii, K.S.; Kovalev, A.S.; Lopaev, D.V.; Mankelevich, Yu.A.; Popov, N.A.; Rakhimov, A.T.; Rakhimova, T.V.

    2005-01-01

    The production of O 2 (a 1 Δ g ) singlet oxygen in non-self-sustained discharges in pure oxygen and mixtures of oxygen with noble gases (Ar or He) was studied experimentally. It is shown that the energy efficiency of O 2 (a 1 Δ g ) production can be optimized with respect to the reduced electric field E/N. It is shown that the optimal E/N values correspond to electron temperatures of 1.2-1.4 eV. At these E/N values, a decrease in the oxygen percentage in the mixture leads to an increase in the excitation rate of singlet oxygen because of the increase in the specific energy deposition per O 2 molecule. The onset of discharge instabilities not only greatly reduces the energy efficiency of singlet oxygen production but also makes it impossible to achieve high energy deposition in a non-self-sustained discharge. A model of a non-self-sustained discharge in pure oxygen is developed. It is shown that good agreement between the experimental and computed results for a discharge in oxygen over a wide range of reduced electric fields can be achieved only by taking into account the ion component of the discharge current. The cross section for the electron-impact excitation of O 2 (a 1 Δ g ) and the kinetic scheme of the discharge processes with the participation of singlet oxygen are verified by comparing the experimental and computed data on the energy efficiency of the production of O 2 (a 1 Δ g ) and the dynamics of its concentration. It is shown that, in the dynamics of O 2 (a 1 Δ g ) molecules in the discharge afterglow, an important role is played by their deexcitation in a three-body reaction with the participation of O( 3 P) atoms. At high energy depositions in a non-self-sustained discharge, this reaction can reduce the maximal attainable concentration of singlet oxygen. The effect of a hydrogen additive to an Ar : O 2 mixture is analyzed based on the results obtained using the model developed. It is shown that, for actual electron beam current densities, a

  19. Nitrous oxide production by nitrification and denitrification in the Eastern Tropical South Pacific oxygen minimum zone

    Science.gov (United States)

    Ji, Qixing; Babbin, Andrew R.; Jayakumar, Amal; Oleynik, Sergey; Ward, Bess B.

    2015-12-01

    The Eastern Tropical South Pacific oxygen minimum zone (ETSP-OMZ) is a site of intense nitrous oxide (N2O) flux to the atmosphere. This flux results from production of N2O by nitrification and denitrification, but the contribution of the two processes is unknown. The rates of these pathways and their distributions were measured directly using 15N tracers. The highest N2O production rates occurred at the depth of peak N2O concentrations at the oxic-anoxic interface above the oxygen deficient zone (ODZ) because slightly oxygenated waters allowed (1) N2O production from both nitrification and denitrification and (2) higher nitrous oxide production yields from nitrification. Within the ODZ proper (i.e., anoxia), the only source of N2O was denitrification (i.e., nitrite and nitrate reduction), the rates of which were reflected in the abundance of nirS genes (encoding nitrite reductase). Overall, denitrification was the dominant pathway contributing the N2O production in the ETSP-OMZ.

  20. Metabolism of the intervertebral disc: effects of low levels of oxygen, glucose, and pH on rates of energy metabolism of bovine nucleus pulposus cells.

    Science.gov (United States)

    Bibby, Susan R S; Jones, Deborah A; Ripley, Ruth M; Urban, Jill P G

    2005-03-01

    In vitro measurements of metabolic rates of isolated bovine nucleus pulposus cells at varying levels of oxygen, glucose, and pH. To obtain quantitative information on the interactions between oxygen and glucose concentrations and pH, and the rates of oxygen and glucose consumption and lactic acid production, for disc nucleus cells. Disc cells depend on diffusion from blood vessels at the disc margins for supply of nutrients. Loss of supply is thought to lead to disc degeneration, but how loss of supply affects nutrient concentrations in the disc is not known; nutrient concentrations within discs can normally only be calculated, because concentration measurements are invasive. However, realistic predictions cannot be made until there are data from measurements of metabolic rates at conditions found in the disc in vivo, i.e., at low levels of oxygen, glucose, and pH. A metabolism chamber was designed to allow simultaneous recording of oxygen and glucose concentrations and of pH. These concentrations were measured electrochemically with custom-built glucose and oxygen sensors; lactic acid was measured biochemically. Bovine nucleus pulposus cells were isolated and inserted into the chamber, and simultaneous rates of oxygen and glucose consumption and of lactic acid production were measured over a range of glucose, oxygen, and pH levels. There were strong interactions between rates of metabolism and oxygen consumption and pH. At atmospheric oxygen levels, oxygen consumption rate at pH 6.2 was 32% of that at pH 7.4. The rate fell by 60% as oxygen concentration was decreased from 21 to 5% at pH 7.4, but only by 20% at pH 6.2. Similar interactions were seen for lactic acid production and glucose consumption rates; we found that glycolysis rates fell at low oxygen and glucose concentrations and low pH. Equations were derived that satisfactorily predict the effect of nutrient and metabolite concentrations on rates of lactic acid production rate and oxygen consumption. Disc

  1. 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

  2. Effect of temperature, of oxygen content and the downstream effect on corrosion rate of structural materials in liquid sodium

    International Nuclear Information System (INIS)

    Ilincev, G.

    1988-01-01

    The effects were experimentally tested of temperature and of oxygen content on the corrosion rate of structural materials in liquid sodium and on reducing the corrosion rate down the sodium stream. The results of the experiments are shown in graphs and tables and are discussed in detail. The duration of all tests was standard 1,000 hours. The test parameters were set such as to determine the effect of temperature on corrosion of a quantity of various materials in sodium with a low oxygen content (1.2 to 2 ppm) at temperatures of 500 to 800 degC and in sodium with a high oxygen content (345 ppm) at temperatures of 500 to 700 degC. More experiments served the determination of the effect of a different oxygen content varying between 1.2 and 2 ppm at a constant temperature of 600 degC. The materials being tested included main structural materials used for fast reactor construction and materials allowing to establish the effect of main alloying elements on their corrosion in liquid sodium of different temperatures and purity grades. The relationships showing the effects of temperature and oxygen content in sodium on the rate of corrosion of various structural materials in hot parts of the installation and on the reduction in the rate of corrosion downstream due to sodium saturation with corrosion products were constructed using the experimental results. (Z.M.). 15 figs., 2 tabs., 7 refs

  3. Technical note: Consistent calculation of aquatic gross production from oxygen triple isotope measurements

    Directory of Open Access Journals (Sweden)

    J. Kaiser

    2011-07-01

    Full Text Available Oxygen triple isotope measurements can be used to calculate aquatic gross oxygen production rates. Past studies have emphasised the appropriate definition of the 17O excess and often used an approximation to derive production rates from the 17O excess. Here, I show that the calculation can be phrased more consistently and without any approximations using the relative 17O/16O and 18O/16O isotope ratio differences (delta values directly. I call this the "dual delta method". The 17O excess is merely a mathematical construct and the derived production rate is independent of its definition, provided all calculations are performed with a consistent definition. I focus on the mixed layer, but also show how time series of triple isotope measurements below the mixed layer can be used to derive gross production.

    In the calculation of mixed layer productivity, I explicitly include isotopic fractionation during gas invasion and evasion, which requires the oxygen supersaturation s to be measured as well. I also suggest how bubble injection could be considered in the same mathematical framework. I distinguish between concentration steady state and isotopic steady state and show that only the latter needs to be assumed in the calculation. It is even possible to derive an estimate of the net production rate in the mixed layer that is independent of the assumption of concentration steady state.

    I review measurements of the parameters required for the calculation of gross production rates and show how their systematic uncertainties as well as the use of different published calculation methods can cause large variations in the production rates for the same underlying isotope ratios. In particular, the 17O excess of dissolved O2 in equilibrium with atmospheric O2 and the 17O excess of photosynthetic O2 need to

  4. Rate of oxygen consumption of hamster melanoma cells as a factor influencing their radioresistance

    International Nuclear Information System (INIS)

    Pajak, S.; Subczynski, W.; Panz, T.; Lukiewicz, S.

    1980-01-01

    It has been reported in recent years that the level of radiosensitivity of neoplasmic cells in vivo and of sphaeroids in vitro can be modified by controlling their rate of oxygen consumption. Thus, an attempt was made to compare this rate in the case of the melanotic and amelanotic lines of Bomirski hamster melanoma in vitro, as it is known that these two lines distinctly differ in their reactivity to ionizing radiations. The measurements carried out by the use of a new ESR method revealed that pigmented and pigmentless cells consume oxygen at significantly different rates. This means that oxygen utilization may contribute to the overall level of radioresistance of melanoma cells. (author)

  5. Effect of oxygen partial pressure on production of animal virus (VSV)

    OpenAIRE

    Lim, Hyun S.; Chang, Kern H.; Kim, Jung H.

    1999-01-01

    The effect of oxygen partial pressure on viral replication was investigated with Vero/VSV system. At 10% oxygen partial pressure in spinner culture, VSV titer was significantly increased 130 fold compared to that obtained at 21%. A similar result was obtained for viral production in 1liter bioreactor. This implies that oxygen partial pressure during viral production has to be low. In low oxygen partial pressure, malondialdehyde concentration was decreased about 5 fold. Thus, low oxygen partia...

  6. 40 CFR 415.490 - Applicability; description of the oxygen and nitrogen production subcategory.

    Science.gov (United States)

    2010-07-01

    ... oxygen and nitrogen production subcategory. 415.490 Section 415.490 Protection of Environment... POINT SOURCE CATEGORY Oxygen and Nitrogen Production Subcategory § 415.490 Applicability; description of the oxygen and nitrogen production subcategory. The provisions of this subpart are applicable to...

  7. Determining Permissible Oxygen and Water Vapor Transmission Rate for Non-Retort Military Ration Packaging

    Science.gov (United States)

    2011-11-01

    OXYGEN AND WATER VAPOR TRANSMISSION RATE FOR NON- RETORT MILITARY RATION PACKAGING by Danielle Froio Alan Wright Nicole Favreau and Sarah...ANSI Std. Z39.18 RETORT STORAGE SHELF LIFE RETORT POUCHES SENSORY ANALYSIS OXYGEN CRACKERS PACKAGING SENSORY... Packaging for MRE. (a) MRE Retort Pouch Quad-Laminate Structure; (b) MRE Non- retort Pouch Tri-Laminate Structure

  8. 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.

  9. A comparative study of oxygen transmission rates through polymer films based on fluorescence quenching

    DEFF Research Database (Denmark)

    Siró, Istvan; Plackett, David; Sommer-Larsen, Peter

    2010-01-01

    Information on oxygen permeability through polymer films is essential for some applications, especially in food packaging where the control of oxygen levels can be critical in avoiding food spoilage. A permeability testing device using fluorescence-based optical oxygen sensing was developed...... as a potential new instrument for measuring the oxygen permeability of packaging films. The fluorescence-based permeability tester was validated against two existing commercial oxygen permeability measuring devices, the Mocon Ox-Tran 2/20 and PBI-Dansensor OPT-5000. Oxygen transmission rates (OTR) of polylactide...... (PLA) and nanoclay-reinforced PLA films, as well as polyethylene/poly(ethylene terephthalate) (PE/PET) and polypropylene/poly(ethylene terephthalate) (PP/PET) laminated films were determined at 23°C and 50% relative humidity using each of these instruments. No significant differences were observed...

  10. Influence of methanol/sorbitol co-feeding rate on pAOX1 induction in a Pichia pastoris Mut+ strain in bioreactor with limited oxygen transfer rate.

    Science.gov (United States)

    Carly, F; Niu, H; Delvigne, F; Fickers, P

    2016-04-01

    High Pichia pastoris biomass density could be obtained using high co-feeding rate of methanol and sorbitol in a fed-batch or continuous culture, while further higher feeding rate finally leads to oxygen limitation in bioreactor. In the literature, there is lack of report about AOX1 promoter regulation with regard to dissolved oxygen level (DO). Therefore, in this work, chemostat cultures were performed to investigate the cell growth, metabolism and regulation of the AOX1 promoter (pAOX1) regarding co-feeding rate of optimized methanol/sorbitol mixture (methanol fraction 0.60 C-mol/C-mol) using a P. pastoris Mut+/pAOX1-lacZ strain. The oxygen transfer rates (OTR) in bioreactor were kept in the range of typical values of large bioreactor, i.e., 4-8 g/(L h) if DO equals 30 % saturation or 5-10 g/(L h) if DO nears zero. For DO >0, an increase of the carbon fed led to an increase of pAOX1 induction. By contrast, when dissolved oxygen was completely depleted, methanol accumulated, causing a 30 % decrease of pAOX1 induction. However, this decrease is more likely to be lined to methanol accumulation than to low level of dissolved oxygen (sorbitol co-feeding allowed cells to adapt to oxygen transient limitations that often occur at industrial scale with reduced effect on pAOX1 induction. The optimal feeding rate tested here was 6.6 mmol C (DCW h)(-1) at an OTR of 8.28 g O2(L h)(-1) with over fivefold pAOX1 induction (probably directly associated with target protein productivity) compared with previous work.

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

    Directory of Open Access Journals (Sweden)

    Isaac Cano

    Full Text Available The production of reactive oxygen species (ROS from the inner mitochondrial membrane is one of many fundamental processes governing the balance between health and disease. It is well known that ROS are necessary signaling molecules in gene expression, yet when expressed at high levels, ROS may cause oxidative stress and cell damage. Both hypoxia and hyperoxia may alter ROS production by changing mitochondrial Po2 (PmO2. Because PmO2 depends on the balance between O2 transport and utilization, we formulated an integrative mathematical model of O2 transport and utilization in skeletal muscle to predict conditions to cause abnormally high ROS generation. Simulations using data from healthy subjects during maximal exercise at sea level reveal little mitochondrial ROS production. However, altitude triggers high mitochondrial ROS production in muscle regions with high metabolic capacity but limited O2 delivery. This altitude roughly coincides with the highest location of permanent human habitation. Above 25,000 ft., more than 90% of exercising muscle is predicted to produce abnormally high levels of ROS, corresponding to the "death zone" in mountaineering.

  12. Seasonal Oxygen Dynamics in a Warm Temperate Estuary: Effects of Hydrologic Variability on Measurements of Primary Production, Respiration, and Net Metabolism

    Science.gov (United States)

    Seasonal responses in estuarine metabolism (primary production, respiration, and net metabolism) were examined using two complementary approaches. Total ecosystem metabolism rates were calculated from dissolved oxygen time series using Odum’s open water method. Water column rates...

  13. Oxygen consumption rates by different oenological tannins in a model wine solution.

    Science.gov (United States)

    Pascual, Olga; Vignault, Adeline; Gombau, Jordi; Navarro, Maria; Gómez-Alonso, Sergio; García-Romero, Esteban; Canals, Joan Miquel; Hermosín-Gutíerrez, Isidro; Teissedre, Pierre-Louis; Zamora, Fernando

    2017-11-01

    The kinetics of oxygen consumption by different oenological tannins were measured in a model wine solution using the non-invasive method based on luminiscence. The results indicate that the oxygen consumption rate follows second-order kinetics depending on tannin and oxygen concentrations. They also confirm that the oxygen consumption rate is influenced by temperature in accordance with Arrhenius law. The indications are that ellagitannins are the fastest oxygen consumers of the different oenological tannins, followed in decreasing order by quebracho tannins, skin tannins, seed tannins and finally gallotannins. This methodology can therefore be proposed as an index for determining the effectiveness of different commercial tannins in protecting wines against oxidation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Microbial degradation rates of small peptides and amino acids in the oxygen minimum zone of Chilean coastal waters

    Science.gov (United States)

    Pantoja, Silvio; Rossel, Pamela; Castro, Rodrigo; Cuevas, L. Antonio; Daneri, Giovanni; Córdova, Candy

    2009-07-01

    We found similar microbial degradation rates of labile dissolved organic matter in oxic and suboxic waters off northern Chile. Rates of peptide hydrolysis and amino acid uptake in unconcentrated water samples were not low in the water column where oxygen concentration was depleted. Hydrolysis rates ranged from 65 to 160 nmol peptide L -1 h -1 in the top 20 m, 8-28 nmol peptide L -1 h -1 between 100 and 300 m (O 2-depleted zone), and 14-19 nmol peptide L -1 h -1 between 600 and 800 m. Dissolved free amino acid uptake rates were 9-26, 3-17, and 6 nmol L -1 h -1 at similar depth intervals. Since these findings are consistent with a model of comparable potential activity of microbes in degrading labile substrates of planktonic origin, we suggest, as do other authors, that differences in decomposition rates with high and low oxygen concentrations may be a matter of substrate lability. The comparison between hydrolysis and uptake rates indicates that microbial peptide hydrolysis occurs at similar or faster rates than amino acid uptake in the water column, and that the hydrolysis of peptides is not a rate-limiting step for the complete remineralization of labile macromolecules. Low O 2 waters process about 10 tons of peptide carbon per h, double the amount processed in surface-oxygenated water. In the oxygen minimum zone, we suggest that the C balance may be affected by the low lability of the dissolved organic matter when this is upwelled to the surface. An important fraction of dissolved organic matter is processed in the oxygen minimum layer, a prominent feature of the coastal ocean in the highly productive Humboldt Current System.

  15. Effects of extracellular zinc ion on the rate of oxygen consumption of ...

    African Journals Online (AJOL)

    The inhibitory effect of extracellular zinc ion on the rate of oxygen consumption of rat brain mitochondria pre-incubated in 1.0 mM Ca2+EDTA were determined. There was a significant increase [P<0.01] in the rate of oxygen consumption in the rat brain mitochondria pre-incubated in 1.0 mM. Ca2+EDTA in a succinate ...

  16. Integrating spatial and temporal oxygen data to improve the quantification of in situ petroleum biodegradation rates.

    Science.gov (United States)

    Davis, Gregory B; Laslett, Dean; Patterson, Bradley M; Johnston, Colin D

    2013-03-15

    Accurate estimation of biodegradation rates during remediation of petroleum impacted soil and groundwater is critical to avoid excessive costs and to ensure remedial effectiveness. Oxygen depth profiles or oxygen consumption over time are often used separately to estimate the magnitude and timeframe for biodegradation of petroleum hydrocarbons in soil and subsurface environments. Each method has limitations. Here we integrate spatial and temporal oxygen concentration data from a field experiment to develop better estimates and more reliably quantify biodegradation rates. During a nine-month bioremediation trial, 84 sets of respiration rate data (where aeration was halted and oxygen consumption was measured over time) were collected from in situ oxygen sensors at multiple locations and depths across a diesel non-aqueous phase liquid (NAPL) contaminated subsurface. Additionally, detailed vertical soil moisture (air-filled porosity) and NAPL content profiles were determined. The spatial and temporal oxygen concentration (respiration) data were modeled assuming one-dimensional diffusion of oxygen through the soil profile which was open to the atmosphere. Point and vertically averaged biodegradation rates were determined, and compared to modeled data from a previous field trial. Point estimates of biodegradation rates assuming no diffusion ranged up to 58 mg kg(-1) day(-1) while rates accounting for diffusion ranged up to 87 mg kg(-1) day(-1). Typically, accounting for diffusion increased point biodegradation rate estimates by 15-75% and vertically averaged rates by 60-80% depending on the averaging method adopted. Importantly, ignoring diffusion led to overestimation of biodegradation rates where the location of measurement was outside the zone of NAPL contamination. Over or underestimation of biodegradation rate estimates leads to cost implications for successful remediation of petroleum impacted sites. Crown Copyright © 2013. Published by Elsevier Ltd. All rights

  17. Radiative losses and electron cooling rates for carbon and oxygen plasma impurities

    International Nuclear Information System (INIS)

    Marchand, R.; Bonnin, X.

    1992-01-01

    Radiative losses and electron cooling rates are calculated for carbon and oxygen ions under conditions relevant to fusion plasmas. Both rates are calculated with the most recent recommended atomic data. A modified coronal model which includes the effects of metastable states is described and used to calculate the rates. Comparisons with other approaches are also discussed. (author). 36 ref, figs

  18. Production of Oxygen from Lunar Regolith by Molten Oxide Electrolysis

    Science.gov (United States)

    Curreri, Peter A.

    2009-01-01

    This paper describes the use of the molten oxide electrolysis (MOE) process for the extraction of oxygen for life support and propellant, and silicon and metallic elements for use in fabrication on the Moon. The Moon is rich in mineral resources, but it is almost devoid of chemical reducing agents, therefore, molten oxide electrolysis is ideal for extraction, since the electron is the only practical reducing agent. MOE has several advantages over other extraction methods. First, electrolytic processing offers uncommon versatility in its insensitivity to feedstock composition. Secondly, oxide melts boast the twin key attributes of highest solubilizing capacity for regolith and lowest volatility of any candidate electrolytes. The former is critical in ensuring high productivity since cell current is limited by reactant solubility, while the latter simplifies cell design by obviating the need for a gas-tight reactor to contain evaporation losses as would be the case with a gas or liquid phase fluoride reagent operating at such high temperatures. Alternatively, MOE requires no import of consumable reagents (e.g. fluorine and carbon) as other processes do, and does not rely on interfacing multiple processes to obtain refined products. Electrolytic processing has the advantage of selectivity of reaction in the presence of a multi-component feed. Products from lunar regolith can be extracted in sequence according to the stabilities of their oxides as expressed by the values of the free energy of oxide formation (e.g. chromium, manganese, Fe, Si, Ti, Al, magnesium, and calcium). Previous work has demonstrated the viability of producing Fe and oxygen from oxide mixtures similar in composition to lunar regolith by molten oxide electrolysis (electrowinning), also called magma electrolysis having shown electrolytic extraction of Si from regolith simulant. This paper describes recent advances in demonstrating the MOE process by a joint project with participation by NASA KSC and

  19. Renal Blood Flow, Glomerular Filtration Rate, and Renal Oxygenation in Early Clinical Septic Shock.

    Science.gov (United States)

    Skytte Larsson, Jenny; Krumbholz, Vitus; Enskog, Anders; Bragadottir, Gudrun; Redfors, Bengt; Ricksten, Sven-Erik

    2018-06-01

    Data on renal hemodynamics, function, and oxygenation in early clinical septic shock are lacking. We therefore measured renal blood flow, glomerular filtration rate, renal oxygen consumption, and oxygenation in patients with early septic shock. Prospective comparative study. General and cardiothoracic ICUs. Patients with norepinephrine-dependent early septic shock (n = 8) were studied within 24 hours after arrival in the ICU and compared with postcardiac surgery patients without acute kidney injury (comparator group, n = 58). None. Data on systemic hemodynamics and renal variables were obtained during two 30-minute periods. Renal blood flow was measured by the infusion clearance of para-aminohippuric acid, corrected for renal extraction of para-aminohippuric acid. Renal filtration fraction was measured by renal extraction of chromium-51 labeled EDTA. Renal oxygenation was estimated from renal oxygen extraction. Renal oxygen delivery (-24%; p = 0.037) and the renal blood flow-to-cardiac index ratio (-21%; p = 0.018) were lower, renal vascular resistance was higher (26%; p = 0.027), whereas renal blood flow tended to be lower (-19%; p = 0.068) in the septic group. Glomerular filtration rate (-32%; p = 0.006) and renal sodium reabsorption (-29%; p = 0.014) were both lower in the septic group. Neither renal filtration fraction nor renal oxygen consumption differed significantly between groups. Renal oxygen extraction was significantly higher in the septic group (28%; p = 0.022). In the septic group, markers of tubular injury were elevated. In early clinical septic shock, renal function was lower, which was accompanied by renal vasoconstriction, a lower renal oxygen delivery, impaired renal oxygenation, and tubular sodium reabsorption at a high oxygen cost compared with controls.

  20. Kinetic bottlenecks to chemical exchange rates for deep-sea animals - Part 1: Oxygen

    Science.gov (United States)

    Hofmann, A. F.; Peltzer, E. T.; Brewer, P. G.

    2012-10-01

    Ocean warming will reduce dissolved oxygen concentrations which can pose challenges to marine life. Oxygen limits are traditionally reported simply as a static concentration thresholds with no temperature, pressure or flow rate dependency. Here we treat the oceanic oxygen supply potential for heterotrophic consumption as a dynamic molecular exchange problem analogous to familiar gas exchange processes at the sea surface. A combination of the purely physico-chemical oceanic properties temperature, hydrostatic pressure, and oxygen concentration defines the ability of the ocean to supply oxygen to any given animal. This general oceanic oxygen supply potential is modulated by animal specific properties such as the diffusive boundary layer thickness to define and limit maximal oxygen supply rates. Here we combine all these properties into formal, mechanistic equations defining novel oceanic properties that subsume various relevant classical oceanographic parameters to better visualize, map, comprehend, and predict the impact of ocean deoxygenation on aerobic life. By explicitly including temperature and hydrostatic pressure into our quantities, various ocean regions ranging from the cold deep-sea to warm, coastal seas can be compared. We define purely physico-chemical quantities to describe the oceanic oxygen supply potential, but also quantities that contain organism-specific properties which in a most generalized way describe general concepts and dependencies. We apply these novel quantities to example oceanic profiles around the world and find that temperature and pressure dependencies of diffusion and partial pressure create zones of greatest physical constriction on oxygen supply typically at around 1000 m depth, which coincides with oxygen concentration minimum zones. In these zones, which comprise the bulk of the world ocean, ocean warming and deoxygenation have a clear negative effect for aerobic life. In some shallow and warm waters the enhanced diffusion and

  1. Plants for water recycling, oxygen regeneration and food production

    Science.gov (United States)

    Bubenheim, D. L.

    1991-01-01

    During long-duration space missions that require recycling and regeneration of life support materials the major human wastes to be converted to usable forms are CO2, hygiene water, urine and feces. A Controlled Ecological Life Support System (CELSS) relies on the air revitalization, water purification and food production capabilities of higher plants to rejuvenate human wastes and replenish the life support materials. The key processes in such a system are photosynthesis, whereby green plants utilize light energy to produce food and oxygen while removing CO2 from the atmosphere, and transpiration, the evaporation of water from the plant. CELSS research has emphasized the food production capacity and efforts to minimize the area/volume of higher plants required to satisfy all human life support needs. Plants are a dynamic system capable of being manipulated to favour the supply of individual products as desired. The size and energy required for a CELSS that provides virtually all human needs are determined by the food production capacity. Growing conditions maximizing food production do not maximize transpiration of water; conditions favoring transpiration and scaling to recycle only water significantly reduces the area, volume, and energy inputs per person. Likewise, system size can be adjusted to satisfy the air regeneration needs. Requirements of a waste management system supplying inputs to maintain maximum plant productivity are clear. The ability of plants to play an active role in waste processing and the consequence in terms of degraded plant performance are not well characterized. Plant-based life support systems represent the only potential for self sufficiency and food production in an extra-terrestrial habitat.

  2. Rate of nova production in the Galaxy

    International Nuclear Information System (INIS)

    Liller, W.; Mayer, B.; PROBLICOM Sky Survey, Los Angeles, CA)

    1987-01-01

    The ongoing PROBLICOM program in the Southern Hemisphere now makes it possible to derive a reliable value for the overall production rate of Galactic novae. The results, 73 + or - 24/y, indicates that the Galaxy outproduces M 31 by a factor of two or three. It is estimated that the rate of supernova ejecta is one and a half orders of magnitude greater than that of novae in the Galaxy. 15 references

  3. Comparative oxygen consumption rates of subitaneous and delayed hatching eggs of the calanoid copepod Acartia tonsa (Dana)

    DEFF Research Database (Denmark)

    Hansen, Benni Winding; Drillet, Guillaume

    2013-01-01

    nanorespirometry to monitor initial oxygen consumption rate of individual eggs of the ubiquitous neritic calanoid copepod Acartia tonsa to distinguish between subitaneous and DHE. We hypothesized that subitaneous eggs exhibit higher initial oxygen consumption rates than DHE, and that initial egg oxygen consumption...... rate is correlated to the time for the individual egg to hatch. Subitaneous eggs exhibited higher initial oxygen consumption rates than DHE and there were no pattern in initial oxygen consumption rates vs. time to hatch or die from the eggs. Variability in initial oxygen consumption rates within...... batches of both subitaneous and DHE, as well as between these egg types, is prevalent. There was a continuum from sluggish- to fast metabolising eggs considering initial oxygen consumption rates most likely reflecting phenotypic variation within cohorts. No matter the individual initial egg oxygen...

  4. Net community production at Ocean Station Papa observed with nitrate and oxygen sensors on profiling floats

    Science.gov (United States)

    Plant, Joshua N.; Johnson, Kenneth S.; Sakamoto, Carole M.; Jannasch, Hans W.; Coletti, Luke J.; Riser, Stephen C.; Swift, Dana D.

    2016-06-01

    Six profiling floats equipped with nitrate and oxygen sensors were deployed at Ocean Station P in the Gulf of Alaska. The resulting six calendar years and 10 float years of nitrate and oxygen data were used to determine an average annual cycle for net community production (NCP) in the top 35 m of the water column. NCP became positive in February as soon as the mixing activity in the surface layer began to weaken, but nearly 3 months before the traditionally defined mixed layer began to shoal from its winter time maximum. NCP displayed two maxima, one toward the end of May and another in August with a summertime minimum in June corresponding to the historical peak in mesozooplankton biomass. The average annual NCP was determined to be 1.5 ± 0.6 mol C m-2 yr-1 using nitrate and 1.5 ± 0.7 mol C m-2 yr-1 using oxygen. The results from oxygen data proved to be quite sensitive to the gas exchange model used as well as the accuracy of the oxygen measurement. Gas exchange models optimized for carbon dioxide flux generally ignore transport due to gas exchange through the injection of bubbles, and these models yield NCP values that are two to three time higher than the nitrate-based estimates. If nitrate and oxygen NCP rates are assumed to be related by the Redfield model, we show that the oxygen gas exchange model can be optimized by tuning the exchange terms to reproduce the nitrate NCP annual cycle.

  5. 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.

  6. Direct Electrolysis of Molten Lunar Regolith for the Production of Oxygen and Metals on the Moon

    Science.gov (United States)

    Sirk, Aislinn H. C.; Sadoway, Donald R.; Sibille, Laurent

    2010-01-01

    When considering the construction of a lunar base, the high cost ($ 100,000 a kilogram) of transporting materials to the surface of the moon is a significant barrier. Therefore in-situ resource utilization will be a key component of any lunar mission. Oxygen gas is a key resource, abundant on earth and absent on the moon. If oxygen could be produced on the moon, this provides a dual benefit. Not only does it no longer need to be transported to the surface for breathing purposes; it can also be used as a fuel oxidizer to support transportation of crew and other materials more cheaply between the surface of the moon, and lower earth orbit (approximately $20,000/kg). To this end a stable, robust (lightly manned) system is required to produce oxygen from lunar resources. Herein, we investigate the feasibility of producing oxygen, which makes up almost half of the weight of the moon by direct electrolysis of the molten lunar regolith thus achieving the generation of usable oxygen gas while producing primarily iron and silicon at the cathode from the tightly bound oxides. The silicate mixture (with compositions and mechanical properties corresponding to that of lunar regolith) is melted at temperatures near 1600 C. With an inert anode and suitable cathode, direct electrolysis (no supporting electrolyte) of the molten silicate is carried out, resulting in production of molten metallic products at the cathode and oxygen gas at the anode. The effect of anode material, sweep rate, and electrolyte composition on the electrochemical behavior was investigated and implications for scale-up are considered. The activity and stability of the candidate anode materials as well as the effect of the electrolyte composition were determined. Additionally, ex-situ capture and analysis of the anode gas to calculate the current efficiency under different voltages, currents and melt chemistries was carried out.

  7. Oxygen permeation flux through La1-ySryFeO3 limited by the carbon monoxide oxidation rate

    NARCIS (Netherlands)

    van Hassel, B.A.; van Hassel, B.A.; ten Elshof, Johan E.; Bouwmeester, Henricus J.M.

    1995-01-01

    The oxygen permeation flux through La1-ySryFeO3-δ (y = 0.1, 0.2) in a large oxygen partial pressure gradient (air/CO, CO2 mixture) was found to be limited by the carbon monoxide oxidation rate at the low oxygen partial pressure side of the membrane. The oxygen permeation flux through the membrane

  8. 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

  9. Oxygen consumption rate and mitochondrial density in human melanoma monolayer cultures and multicellular spheroids.

    Science.gov (United States)

    Hystad, M E; Rofstad, E K

    1994-05-15

    Rate of oxygen consumption per cell has been shown in previous studies to decrease with increasing depth in the viable rim of multicellular spheroids initiated from rodent cells, human colon-carcinoma cells, and human glioma cells, due to progressive accumulation of quiescent cells during spheroid growth. The purpose of our work was to determine oxygen-consumption profiles in human melanoma spheroids. Monolayer cultures of 4 lines (BEX-c, COX-c, SAX-c, and WIX-c) and spheroid cultures of 2 lines (BEX-c and WIX-c) were subjected to investigation. Spheroids were initiated from monolayer cell cultures and grown in spinner flasks. Rate of oxygen consumption was measured with a Clarke-type electrode. Mitochondrial density was determined by stereological analysis of transmission electron micrographs. Thickness of viable rim and cell packing density were assessed by light microscopy of central spheroid sections. Cell-cycle distribution was determined by analysis of DNA histograms measured by flow cytometry. Cell volume was measured by an electronic particle counter. Rate of oxygen consumption per cell differed by a factor of approximately 1.8 between the 4 cell lines and was positively correlated to total volume of mitochondria per cell. Rate of oxygen consumption per cell and total volume of mitochondria per cell were equal for monolayer cell cultures, 600-microns spheroids and 1,200-microns spheroids of the same line. Mitochondrial density and location in the cell did not differ between cells at the spheroid surface, in the middle of the viable rim and adjacent to the central necrosis. Cell-cycle distribution, cell volume, and cell-packing density in the outer and inner halves of the viable rim were not significantly different. Consequently, the rate of oxygen consumption per cell in inner regions of the viable rim was probably equal to that at the spheroid surface, suggesting that oxygen diffusion distances may be shorter in some melanomas than in many other tumor

  10. Oxygen-15 labelled water production for positron emission tomography

    International Nuclear Information System (INIS)

    Janus, A.; Sachinidis, J.I.; Chan, J.G.; Tochon-Danguy, H.J.

    1998-01-01

    Full text: Functional imaging using positron emission tomography (PET) and 15 O-labelled compounds is both scientifically and clinically challenging. The short half-life of oxygen-15 (t 1/2 = 2 min) allows for multiple administration to a patient without exceeding acceptable levels of absorbed radiation dose and without excessive delay between administrations. The clinical usefulness of [ 15 O]-labelled water for cerebral blood flow measurements has been well established. Here we report the development and construction of a [ 15 O]water generator based on an earlier design from Hammersmith Hospital, London. The cyclotron produces a continuous flow of [ 15 O]O 2 gas by the irradiation of a natural nitrogen target (1% O 2 in N 2 ) with a 5 MeV deuteron beam, via the nuclear reaction ( 14 N(d,n) 15 O). The radioactive gas is then mixed with 5% hydrogen in nitrogen and piped to the water generator located in the scanner room. The O 2 /N 2 gas mixture is reacted over a palladium catalyst at 1500 deg C to produce [ 15 O]H 2 O vapour. The vapour passes through an exchanger where it diffuses across a semi-permeable membrane (cellulose acetate) into saline solution. At the optimum gas flow- rate of 500 mL/min, more than 95% of the radioactive oxygen is converted to radioactive water. Waste radioactive gas is piped back to the cyclotron vault to decay before release into the atmosphere. The saline solution (0.9% NaCl) is pumped continuously through the system at 6 mL/min with an infusion pump (3M AVI470). The present system has been in operation for more than a year and has been used for clinical evaluation of stroke patients and for brain activation research studies

  11. Oxygen transfer rate estimation in oxidation ditches from clean water measurements.

    Science.gov (United States)

    Abusam, A; Keesman, K J; Meinema, K; Van Straten, G

    2001-06-01

    Standard methods for the determination of oxygen transfer rate are based on assumptions that are not valid for oxidation ditches. This paper presents a realistic and simple new method to be used in the estimation of oxygen transfer rate in oxidation ditches from clean water measurements. The new method uses a loop-of-CSTRs model, which can be easily incorporated within control algorithms, for modelling oxidation ditches. Further, this method assumes zero oxygen transfer rates (KLa) in the unaerated CSTRs. Application of a formal estimation procedure to real data revealed that the aeration constant (k = KLaVA, where VA is the volume of the aerated CSTR) can be determined significantly more accurately than KLa and VA. Therefore, the new method estimates k instead of KLa. From application to real data, this method proved to be more accurate than the commonly used Dutch standard method (STORA, 1980).

  12. Predictive Finite Rate Model for Oxygen-Carbon Interactions at High Temperature

    Science.gov (United States)

    Poovathingal, Savio

    An oxidation model for carbon surfaces is developed to predict ablation rates for carbon heat shields used in hypersonic vehicles. Unlike existing empirical models, the approach used here was to probe gas-surface interactions individually and then based on an understanding of the relevant fundamental processes, build a predictive model that would be accurate over a wide range of pressures and temperatures, and even microstructures. Initially, molecular dynamics was used to understand the oxidation processes on the surface. The molecular dynamics simulations were compared to molecular beam experiments and good qualitative agreement was observed. The simulations reproduced cylindrical pitting observed in the experiments where oxidation was rapid and primarily occurred around a defect. However, the studies were limited to small systems at low temperatures and could simulate time scales only of the order of nanoseconds. Molecular beam experiments at high surface temperature indicated that a majority of surface reaction products were produced through thermal mechanisms. Since the reactions were thermal, they occurred over long time scales which were computationally prohibitive for molecular dynamics to simulate. The experiments provided detailed dynamical data on the scattering of O, O2, CO, and CO2 and it was found that the data from molecular beam experiments could be used directly to build a model. The data was initially used to deduce surface reaction probabilities at 800 K. The reaction probabilities were then incorporated into the direct simulation Monte Carlo (DSMC) method. Simulations were performed where the microstructure was resolved and dissociated oxygen convected and diffused towards it. For a gas-surface temperature of 800 K, it was found that despite CO being the dominant surface reaction product, a gas-phase reaction forms significant CO2 within the microstructure region. It was also found that surface area did not play any role in concentration of

  13. Controlled temperature expansion in oxygen production by molten alkali metal salts

    Science.gov (United States)

    Erickson, Donald C.

    1985-06-04

    A continuous process is set forth for the production of oxygen from an oxygen containing gas stream, such as air, by contacting a feed gas stream with a molten solution of an oxygen acceptor to oxidize the acceptor and cyclically regenerating the oxidized acceptor by releasing oxygen from the acceptor wherein the oxygen-depleted gas stream from the contact zone is treated sequentially to temperature reduction by heat exchange against the feed stream so as to condense out entrained oxygen acceptor for recycle to the process, combustion of the gas stream with fuel to elevate its temperature and expansion of the combusted high temperature gas stream in a turbine to recover power.

  14. Single Cell Responses to Spatially Controlled Photosensitized Production of Extracellular Singlet Oxygen

    DEFF Research Database (Denmark)

    Pedersen, Brian Wett; Sinks, Louise E.; Breitenbach, Thomas

    2011-01-01

    The response of individual HeLa cells to extracellularly produced singlet oxygen was examined. The spatial domain of singlet oxygen production was controlled using the combination of a membrane-impermeable Pd porphyrin-dendrimer, which served as a photosensitizer, and a focused laser, which served...... to localize the sensitized production of singlet oxygen. Cells in close proximity to the domain of singlet oxygen production showed morphological changes commonly associated with necrotic cell death. The elapsed post-irradiation “waiting period” before necrosis became apparent depended on (a) the distance...... between the cell membrane and the domain irradiated, (b) the incident laser fluence and, as such, the initial concentration of singlet oxygen produced, and (c) the lifetime of singlet oxygen. The data imply that singlet oxygen plays a key role in this process of light-induced cell death. The approach...

  15. Pleiotropic Effects of Biguanides on Mitochondrial Reactive Oxygen Species Production

    Directory of Open Access Journals (Sweden)

    Alena Pecinova

    2017-01-01

    Full Text Available Metformin is widely prescribed as a first-choice antihyperglycemic drug for treatment of type 2 diabetes mellitus, and recent epidemiological studies showed its utility also in cancer therapy. Although it is in use since the 1970s, its molecular target, either for antihyperglycemic or antineoplastic action, remains elusive. However, the body of the research on metformin effect oscillates around mitochondrial metabolism, including the function of oxidative phosphorylation (OXPHOS apparatus. In this study, we focused on direct inhibitory mechanism of biguanides (metformin and phenformin on OXPHOS complexes and its functional impact, using the model of isolated brown adipose tissue mitochondria. We demonstrate that biguanides nonspecifically target the activities of all respiratory chain dehydrogenases (mitochondrial NADH, succinate, and glycerophosphate dehydrogenases, but only at very high concentrations (10−2–10−1 M that highly exceed cellular concentrations observed during the treatment. In addition, these concentrations of biguanides also trigger burst of reactive oxygen species production which, in combination with pleiotropic OXPHOS inhibition, can be toxic for the organism. We conclude that the beneficial effect of biguanides should probably be associated with subtler mechanism, different from the generalized inhibition of the respiratory chain.

  16. Mitigating an increase of specific power consumption in a cryogenic air separation unit at reduced oxygen production

    Science.gov (United States)

    Singla, Rohit; Chowdhury, Kanchan

    2017-02-01

    Specific power consumed in a Linde double column air separation unit (ASU) increases as the quantity of oxygen produced at a given purity is decreased due to the changes of system requirement or market demand. As the plant operates in part load condition, the specific power consumption (SPC) increases as the total power consumption remains the same. In order to mitigate the increase of SPC at lower oxygen production, the operating pressure of high pressure column (HPC) can be lowered by extending the low pressure column (LPC) by a few trays and adding a second reboiler. As the duty of second reboiler in LPC is increased, the recovery of oxygen decreases with a lowering of the HPC pressure. This results in mitigation of the increase of SPC of the plant. A Medium pressure ASU with dual reboiler that produces pressurised gaseous and liquid products of oxygen and nitrogen is simulated in Aspen Hysys 8.6®, a commercial process simulator to determine SPC at varying oxygen production. The effects of reduced pressure of air feed into the cold box on the size of heat exchangers (HX) are analysed. Operation strategy to obtain various oxygen production rates at varying demand is also proposed.

  17. Effective oxygen-consumption rates in fermentation broths with filamentous organisms

    Energy Technology Data Exchange (ETDEWEB)

    Reuss, M; Bajpai, R K; Berke, W

    1982-01-01

    The concept of coupling molecular diffusion and reaction has been applied in the past to various biological systems with clearly defined geometrical properties like pellets and immobilised enzymes/microorganisms. This paper investigates the use of the same principle to characterise the diffusional limitation in suspensions of filamentous microorganisms. Experimental results of oxygen-uptake measurements from Aspergillus niger fermentations in a 50 cu.dm turbine-agitated fermentor are presented with theoretical predictions of coupled diffusion and oxygen kinetics. Results are discussed on the basis of turbulence theory so that the mycelial broth can be structured in hypothetical spherical elements. Consideration of local energy-dissipation rates in the impeller region provides reasonable explanation of the strong influence of the impeller/tank diameter ratio on the effective oxygen-uptake rate at a given power input. (Refs. 18).

  18. Preparation and use of nitrogen (2) oxide of special purity for production of oxygen and nitrogen isotopes

    International Nuclear Information System (INIS)

    Polevoj, A.S.

    1989-01-01

    Problems related with production of oxygen and nitrogen isotopes by means of low-temperature rectification of nitrogen (2) oxide are analyzed. Special attention, in particular, is payed to the techniques of synthesis and high purification of initial NO, utilization of waste flows formed during isotope separation. Ways to affect the initial isotope composition of nitrogen oxide and the rate of its homogeneous-isotope exchange, which provide for possibility of simultaneous production of oxygen and nitrogen isotopes by means of NO rectification, are considered. Description of a new technique for high purification of nitrogen oxide, prepared at decomposition of nitric acid by sulfurous anhydride, suggested by the author is presented

  19. Oxygen isotope exchange rate between dissolved sulfate and water at hydrothermal temperatures

    International Nuclear Information System (INIS)

    Chiba, H.; Sakai, H.

    1985-01-01

    Oxygen isotope exchange rate between dissolved sulfate and water was experimentally determined at 100, 200 and 300 deg C. The isotope exchange rate is strongly dependent on temperature and pH of the solution. Combining the temperature and pH dependence of the reaction rate, the exchange reaction was estimated to be first-order with respect to sulfate. The logarithm of apparent rate constant of exchange reaction at a given temperature is a function of the pH calculated at the experimental temperatures. From the pH dependence of the apparent rate constant, it was deduced that the isotope exchange reaction between dissolved sulfate and water proceeds through collision between H 2 SO 4 0 and H 2 O at low pH, and between HSO 4 - and H 2 O at intermediate pH. The isotope exchange rate obtained indicates that oxygen isotope geothermometry utilizing the studied isotope exchange is suitable for temperature estimation of geothermal reservoirs. The extrapolated half-life of this reaction to oceanic temperature is about 10 9 years, implying that exchange between oceanic sulfate and water cannot control the oxygen isotope ratio of oceanic sulfates. (author)

  20. Energy deposition and ion production from thermal oxygen ion precipitation during Cassini's T57 flyby

    Science.gov (United States)

    Snowden, Darci; Smith, Michael; Jimson, Theodore; Higgins, Alex

    2018-05-01

    Cassini's Radio Science Investigation (RSS) and Langmuir Probe observed abnormally high electron densities in Titan's ionosphere during Cassini's T57 flyby. We have developed a three-dimensional model to investigate how the precipitation of thermal magnetospheric O+ may have contributed to enhanced ion production in Titan's ionosphere. The three-dimensional model builds on previous work because it calculates both the flux of oxygen through Titan's exobase and the energy deposition and ion production rates in Titan's atmosphere. We find that energy deposition rates and ion production rates due to thermal O+ precipitation have a similar magnitude to the rates from magnetospheric electron precipitation and that the simulated ionization rates are sufficient to explain the abnormally high electron densities observed by RSS and Cassini's Langmuir Probe. Globally, thermal O+ deposits less energy in Titan's atmosphere than solar EUV, suggesting it has a smaller impact on the thermal structure of Titan's neutral atmosphere. However, our results indicate that thermal O+ precipitation can have a significant impact on Titan's ionosphere.

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

    International Nuclear Information System (INIS)

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

    1983-01-01

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

  2. Oxygen consumption rate v. rate of energy utilization of fishes: a comparison and brief history of the two measurements.

    Science.gov (United States)

    Nelson, J A

    2016-01-01

    Accounting for energy use by fishes has been taking place for over 200 years. The original, and continuing gold standard for measuring energy use in terrestrial animals, is to account for the waste heat produced by all reactions of metabolism, a process referred to as direct calorimetry. Direct calorimetry is not easy or convenient in terrestrial animals and is extremely difficult in aquatic animals. Thus, the original and most subsequent measurements of metabolic activity in fishes have been measured via indirect calorimetry. Indirect calorimetry takes advantage of the fact that oxygen is consumed and carbon dioxide is produced during the catabolic conversion of foodstuffs or energy reserves to useful ATP energy. As measuring [CO2 ] in water is more challenging than measuring [O2 ], most indirect calorimetric studies on fishes have used the rate of O2 consumption. To relate measurements of O2 consumption back to actual energy usage requires knowledge of the substrate being oxidized. Many contemporary studies of O2 consumption by fishes do not attempt to relate this measurement back to actual energy usage. Thus, the rate of oxygen consumption (M˙O2 ) has become a measurement in its own right that is not necessarily synonymous with metabolic rate. Because all extant fishes are obligate aerobes (many fishes engage in substantial net anaerobiosis, but all require oxygen to complete their life cycle), this discrepancy does not appear to be of great concern to the fish biology community, and reports of fish oxygen consumption, without being related to energy, have proliferated. Unfortunately, under some circumstances, these measures can be quite different from one another. A review of the methodological history of the two measurements and a look towards the future are included. © 2016 The Fisheries Society of the British Isles.

  3. Factors determining the oxygen consumption rate (VO2) on-kinetics in skeletal muscles.

    OpenAIRE

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2004-01-01

    Using a computer model of oxidative phosphorylation developed previously [Korzeniewski and Mazat (1996) Biochem. J. 319, 143-148; Korzeniewski and Zoladz (2001) Biophys. Chem. 92, 17-34], we analyse the effect of several factors on the oxygen-uptake kinetics, especially on the oxygen consumption rate (VO2) and half-transition time t(1/2), at the onset of exercise in skeletal muscles. Computer simulations demonstrate that an increase in the total creatine pool [PCr+/-Cr] (where Cr stands for c...

  4. Production of pulsed atomic oxygen beams via laser vaporization methods

    International Nuclear Information System (INIS)

    Brinza, D.E.; Coulter, D.R.; Liang, R.H.; Gupta, A.

    1987-01-01

    Energetic pulsed atomic oxygen beams were generated by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin films of indium-tin oxide (ITO). Mass and energy characterization of beams from the ozone/oxygen films were carried out by mass spectrometry. The peak flux, found to occur at 10 eV, is estimated from this data to be 3 x 10(20) m(-2) s(-1). Analysis of the time-of-flight data indicates a number of processes contribute to the formation of the atomic oxygen beam. The absence of metastable states such as the 2p(3) 3s(1) (5S) level of atomic oxygen blown off from ITO films is supported by the failure to observe emission at 777.3 nm from the 2p(3) 3p(1) (5P/sub J/) levels. Reactive scattering experiments with polymer film targets for atomic oxygen bombardment are planned using a universal crossed molecular beam apparatus

  5. Watershed Influences on Residence Time and Oxygen Reduction Rates in an Agricultural Landscape

    Science.gov (United States)

    Shope, C. L.; Tesoriero, A. J.

    2015-12-01

    Agricultural use of synthetic fertilizers and animal manure has led to increased crop production, but also elevated nitrogen concentrations in groundwater, resulting in impaired water quality. Groundwater oxygen concentrations are a key indicator of potential biogeochemical processes, which control water/aquifer interactions and contaminant transport. The U.S. Geological Survey's National Water-Quality Assessment Program has a long-history of studying nutrient transport and processing across the United States and the Glacial Aquifer system in particular. A series of groundwater well networks in Eastern Wisconsin is being used to evaluate the distribution of redox reaction rates over a range of scales with a focus on dissolved O2 reduction rates. An analysis of these multi-scale networks elucidates the influence of explanatory variables (i.e.: soil type, land use classification) on reduction rates and redox reactions throughout the Fox-Wolf-Peshtigo watersheds. Multiple tracers including dissolved gasses, tritium, helium, chlorofluorocarbons, sulfur hexafluoride, and carbon-14 were used to estimate groundwater ages (0.8 to 61.2 yr) at over 300 locations. Our results indicate O2 reduction rates along a flowpath study area (1.2 km2) of 0.15 mg O2 L-1 yr-1 (0.12 to 0.18 mg O2 L-1 yr-1) up to 0.41 mg O2 L-1 yr-1 (0.23 to 0.89 mg O2 L-1 yr-1) for a larger scale land use study area (3,300 km2). Preliminary explanatory variables that can be used to describe the variability in reduction rates include soil type (hydrologic group, bulk density) and chemical concentrations (nitrite plus nitrate, silica). The median residence time expected to reach suboxic conditions (≤ 0.4 mg O2 L-1) for the flowpath and the land use study areas was 66 and 25 yr, respectively. These results can be used to elucidate and differentiate the impact of residence time on groundwater quality vulnerability and sustainability in agricultural regions without complex flow models.

  6. Maximum entropy production rate in quantum thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Beretta, Gian Paolo, E-mail: beretta@ing.unibs.i [Universita di Brescia, via Branze 38, 25123 Brescia (Italy)

    2010-06-01

    In the framework of the recent quest for well-behaved nonlinear extensions of the traditional Schroedinger-von Neumann unitary dynamics that could provide fundamental explanations of recent experimental evidence of loss of quantum coherence at the microscopic level, a recent paper [Gheorghiu-Svirschevski 2001 Phys. Rev. A 63 054102] reproposes the nonlinear equation of motion proposed by the present author [see Beretta G P 1987 Found. Phys. 17 365 and references therein] for quantum (thermo)dynamics of a single isolated indivisible constituent system, such as a single particle, qubit, qudit, spin or atomic system, or a Bose-Einstein or Fermi-Dirac field. As already proved, such nonlinear dynamics entails a fundamental unifying microscopic proof and extension of Onsager's reciprocity and Callen's fluctuation-dissipation relations to all nonequilibrium states, close and far from thermodynamic equilibrium. In this paper we propose a brief but self-contained review of the main results already proved, including the explicit geometrical construction of the equation of motion from the steepest-entropy-ascent ansatz and its exact mathematical and conceptual equivalence with the maximal-entropy-generation variational-principle formulation presented in Gheorghiu-Svirschevski S 2001 Phys. Rev. A 63 022105. Moreover, we show how it can be extended to the case of a composite system to obtain the general form of the equation of motion, consistent with the demanding requirements of strong separability and of compatibility with general thermodynamics principles. The irreversible term in the equation of motion describes the spontaneous attraction of the state operator in the direction of steepest entropy ascent, thus implementing the maximum entropy production principle in quantum theory. The time rate at which the path of steepest entropy ascent is followed has so far been left unspecified. As a step towards the identification of such rate, here we propose a possible

  7. The relationship between heart rate and rate of oxygen consumption in Galapagos marine iguanas (Amblyrhynchus cristatus) at two different temperatures.

    Science.gov (United States)

    Butler, Patrick J; Frappell, Peter B; Wang, Tobias; Wikelski, Martin

    2002-07-01

    To enable the use of heart rate (fH) for estimating field metabolic rate (FMR) in free-ranging Galapagos marine iguanas Amblyrhynchus cristatus, we determined the relationships between fH and mass-specific rate of oxygen consumption (sVO2) in seven iguanas before and during exercise on a treadmill and during the post-exercise period. The experiments were conducted at 27 and 35 degrees C, which are the temperatures that represent the lowest and highest average body temperatures of these animals in the field during summer. There were linear and significant relationships between fH and sVO2 at both temperatures (r(2)=0.86 and 0.91 at 27 degrees C and 36 degrees C, respectively). The slopes of the two regression lines did not differ, but there were significant differences in their intercepts. Thus, while heart rate can be used to predict FMR, the effects of temperature on the intercept of the regression must be taken into account when converting fH to sVO2. On the basis of our data, this can be achieved by applying the following formula: sVO2=0.0113fH-0.2983Q(10)((T(b)-27)/10). The increase in sVO2 with elevated body temperature results from an increase in fH, with no significant change in mass-specific oxygen pulse (sO(2) pulse; cardiac stroke volume times the difference in oxygen content between arterial and mixed venous blood). However, during exercise at both temperatures, increases in fH are insufficient to provide all of the additional O(2) required and there are also significant increases in the sO(2) pulses. This creates the situation whereby the same fH at the two temperatures can represent different values of sVO2.

  8. Strategies to overcome oxygen transfer limitations during hairy root cultivation of Azadiracta indica for enhanced azadirachtin production.

    Science.gov (United States)

    Srivastava, Smita; Srivastava, Ashok Kumar

    2012-07-01

    The vast untapped potential of hairy root cultures as a stable source of biologically active chemicals has focused the attention of scientific community toward its commercial exploitation. However, the major bottleneck remains its successful scale-up. Due to branching, the roots form an interlocked matrix that exhibits resistance to oxygen transfer. Thus, present work was undertaken to develop cultivation strategies like optimization of inlet gas composition (in terms of % (v/v) O(2) in air), air-flow rate and addition of oxygen vectors in the medium, to curb the oxygen transfer limitations during hairy root cultivation of Azadirachta indica for in vitro azadirachtin (a biopesticide) production. It was found that increasing the oxygen fraction in the inlet air (in the range, 20-100% (v/v) O(2) in air) increased the azadirachtin productivity by approximately threefold, to a maximum of 4.42 mg/L per day (at 100% (v/v) O(2) in air) with respect to 1.68 mg/L per day in control (air with no oxygen supplementation). Similarly, increasing the air-flow rate (in the range, 0.3-2 vvm) also increased the azadirachtin productivity to a maximum of 1.84 mg/L per day at 0.8 vvm of air-flow rate. On the contrary, addition of oxygen vectors (in the range, 1-4% (v/v); hydrogen peroxide, toluene, Tween 80, kerosene, silicone oil, and n-hexadecane), decreased the azadirachtin productivity with respect to control (1.76 mg/L per day).

  9. Nitrous oxide production during nitrification from organic solid waste under temperature and oxygen conditions.

    Science.gov (United States)

    Nag, Mitali; Shimaoka, Takayuki; Komiya, Teppei

    2016-11-01

    Landfill aeration can accelerate the biological degradation of organic waste and reduce methane production; however, it induces nitrous oxide (N2O), a potent greenhouse gas. Nitrification is one of the pathways of N2O generation as a by-product during aerobic condition. This study was initiated to demonstrate the features of N2O production rate from organic solid waste during nitrification under three different temperatures (20°C, 30°C, and 40°C) and three oxygen concentrations (5%, 10%, and 20%) with high moisture content and high substrates' concentration. The experiment was carried out by batch experiment using Erlenmeyer flasks incubated in a shaking water bath for 72 h. A duplicate experiment was carried out in parallel, with addition of 100 Pa of acetylene as a nitrification inhibitor, to investigate nitrifiers' contribution to N2O production. The production rate of N2O ranged between 0.40 × 10(-3) and 1.14 × 10(-3) mg N/g-DM/h under the experimental conditions of this study. The rate of N2O production at 40°C was higher than at 20°C and 30°C. Nitrification was found to be the dominant pathway of N2O production. It was evaluated that optimization of O2 content is one of the crucial parameters in N2O production that may help to minimize greenhouse gas emissions and N turnover during aeration.

  10. Measurement of ozone production scaling in a helium plasma jet with oxygen admixture

    Science.gov (United States)

    Sands, Brian; Ganguly, Biswa

    2012-10-01

    Capillary dielectric barrier plasma jet devices that generate confined streamer-like discharges along a rare gas flow can produce significant quantities of reactive oxygen species with average input powers ranging from 100 mW to >1 W. We have measured spatially-resolved ozone production in a He plasma jet with O2 admixture concentrations up to 5% using absorption spectroscopy of the O3 Hartley band system. A 20-ns risetime, 10-13 kV positive unipolar voltage pulse train was used to power the discharge, with pulse repetition rates varied from 1-20 kHz. The discharge was operated in a transient glow mode to scale the input power by adjusting the gap width between the anode and downstream cathodic plane. Peak ozone number densities in the range of 10^16 - 10^17 cm-3 were measured. At a given voltage, the density of ozone increased monotonically up to 3% O2 admixture (6 mm gap) as the peak discharge current decreased by an order of magnitude. Ozone production increased with distance from the capillary, consistent with observations by other groups. Atomic oxygen production inferred from O-atom 777 nm emission intensity did not scale with ozone as the input power was increased. The spatial distribution of ozone and scaling with input power will be presented.

  11. Polymer growth rate in a wire chamber with oxygen, water, or alcohol gas additives

    International Nuclear Information System (INIS)

    Boyarski, Adam M.

    2009-01-01

    The rate of polymer growth on wires was measured in a wire chamber while the chamber was aged initially with helium:isobutane (80:20) gas, and then with either oxygen, water, or alcohol added to the gas. At the completion of the aging process for each gas mixture, the carbon content on the wires was measured in a scanning electron microscope/energy dispersive X-ray (SEM/EDX) instrument. The same physical wires were used in all the gas mixtures, allowing measurement of polymer build-up or polymer depletion by each gas additive. It is found that the rate of polymer growth is not changed by the presence of oxygen, water, or alcohol. Conjecture that oxygen reduces breakdown by removing polymer deposits on field wires is negated by these measurements. Instead, it appears that the reduced breakdown is due to lower resistance in the polymer from oxygen ions being transported into the polymer. It is also observed that field wires bombarded by the electrons in the SEM and then placed back into the chamber show an abundance of single electrons being emitted, indicating that electron charge is trapped in the polymer layer and that a high electric field is necessary to remove the charge.

  12. Apparent oxygen utilization rates calculated from tritium and helium-3 profiles at the Bermuda Atlantic Time-series Study site

    Directory of Open Access Journals (Sweden)

    R. H. R. Stanley

    2012-06-01

    Full Text Available We present three years of Apparent Oxygen Utilization Rates (AOUR estimated from oxygen and tracer data collected over the ocean thermocline at monthly resolution between 2003 and 2006 at the Bermuda Atlantic Time-series Study (BATS site. We estimate water ages by calculating a transit time distribution from tritium and helium-3 data. The vertically integrated AOUR over the upper 500 m, which is a regional estimate of export, during the three years is 3.1 ± 0.5 mol O2 m−2 yr−1. This is comparable to previous AOUR-based estimates of export production at the BATS site but is several times larger than export estimates derived from sediment traps or 234Th fluxes. We compare AOUR determined in this study to AOUR measured in the 1980s and show AOUR is significantly greater today than decades earlier because of changes in AOU, rather than changes in ventilation rates. The changes in AOU are likely a methodological artefact associated with problems with early oxygen measurements.

  13. Temperature controls oxidative phosphorylation and reactive oxygen species production through uncoupling in rat skeletal muscle mitochondria.

    Science.gov (United States)

    Jarmuszkiewicz, Wieslawa; Woyda-Ploszczyca, Andrzej; Koziel, Agnieszka; Majerczak, Joanna; Zoladz, Jerzy A

    2015-06-01

    Mitochondrial respiratory and phosphorylation activities, mitochondrial uncoupling, and hydrogen peroxide formation were studied in isolated rat skeletal muscle mitochondria during experimentally induced hypothermia (25 °C) and hyperthermia (42 °C) compared to the physiological temperature of resting muscle (35 °C). For nonphosphorylating mitochondria, increasing the temperature from 25 to 42 °C led to a decrease in membrane potential, hydrogen peroxide production, and quinone reduction levels. For phosphorylating mitochondria, no temperature-dependent changes in these mitochondrial functions were observed. However, the efficiency of oxidative phosphorylation decreased, whereas the oxidation and phosphorylation rates and oxidative capacities of the mitochondria increased, with increasing assay temperature. An increase in proton leak, including uncoupling protein-mediated proton leak, was observed with increasing assay temperature, which could explain the reduced oxidative phosphorylation efficiency and reactive oxygen species production. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. A new look at oxygen production on Mars - In situ propellant production (ISPP)

    Science.gov (United States)

    Frisbee, Robert H.; French, James R., Jr.; Lawton, Emil A.

    1987-01-01

    Consideration is given to the technique of producing oxygen on Mars from CO2 in the Martian atmosphere via in situ propellent production (ISPP). Mission implications of ISPP for both manned and unmanned Mars missions are described as well as ways to improve system reliability. Technology options that improve reliability and reduce power requirements include the use of adsorption pumps and advanced zirconia membranes. It is concluded that both manned and unmanned missions will benefit greatly from ISPP, especially in the context of a permanent manned base on Mars.

  15. Measurement of infiltration rates in urban sewer systems by use of oxygen isotopes.

    Science.gov (United States)

    De Bénédittis, J; Bertrand-Krajewski, J L

    2005-01-01

    The paper presents the principle of a method to measure infiltration rates in sewer systems based on the use of oxygen isotopes and its application in Lyon (France). In the urban area of Lyon, significant differences in delta 18O that can reach 3 per thousand are observed between the oxygen isotopic compositions of groundwater originating from Rhone, Saone and from their associated alluvial aquifers. Drinking water supplying Lyon results mainly from pumping in the Rhone alluvial aquifer. Therefore, in some areas, the difference of isotopic composition between wastewater resulting from the consumption of drinking water and local groundwater can be used to measure infiltration in sewer systems. The application in the catchment of Ecully shows that the infiltration flow rate presents strong fluctuations at an hourly scale: it varies between 15 and 40 m3/h. This variability could be explained by non-constant discharges of pumping and by variations of the water level in the sewer.

  16. Rate constant for the reaction of atomic oxygen with phosphine at 298 K

    Science.gov (United States)

    Stief, L. J.; Payne, W. A.; Nava, D. F.

    1987-01-01

    The rate constant for the reaction of atomic oxygen with phosphine has been measured at 298 K using flash photolysis combined with time-resolved detection of O(3P) via resonance fluorescence. Atomic oxygen was produced by flash photolysis of N2O or NO highly diluted in argon. The results were shown to be independent of (PH3), (O), total pressure and the source of O(3P). The mean value of all the experiments is k1 = (3.6 + or -0.8) x 10 to the -11th cu cm/s (1 sigma). Two previous measurements of k1 differed by more than an order of magnitude, and the results support the higher value obtained in a discharge flow-mass spectrometry study. A comparison with rate data for other atomic and free radical reactions with phosphine is presented, and the role of these reactions in the aeronomy or photochemistry of Jupiter and Saturn is briefly considered.

  17. Effect of oxygen supply on Monascus pigments and citrinin production in submerged fermentation.

    Science.gov (United States)

    Yang, Jian; Chen, Qi; Wang, Weiping; Hu, Jiajun; Hu, Chuan

    2015-05-01

    The influence of oxygen supply on Monascus pigments and citrinin production by Monascus ruber HS.4000 in submerged fermentation was studied. For Monascus cultivation with high pigments and low citrinin production, the initial growth phase, mid-stage phase, and later-stage production phase were separated by shifting oxygen supply. The optimal condition for the fermentation process in shake-flask fermentation was a three-stage rotating rate controlled strategy (0-48 h at 150 rpm, 48-108 h at 250 rpm, 108-120 h at 200 rpm) with medium volume of 100 mL added to 250 mL Erlenmeyer flasks at 30°C for 120 h cultivation. Compared to constant one-stage cultivation (medium volume of 100 mL, rotating rate of 250 rpm), the pigments were reduced by 40.4%, but citrinin was reduced by 64.2%. The most appropriate condition for the fermentation process in a 10 L fermentor is also a three-stage aeration process (0-48 h at 300 L/h, 48-96 h at 500 L/h, 96-120 h at 200 L/h) with agitation of 300 rpm at 30°C for 120 h cultivation, and 237.3 ± 5.7 U/mL pigments were produced in 120 h with 6.05 ± 0.19 mg/L citrinin in a 10 L fermentor. Compared to aeration-constant (500 L/h) cultivation, pigment production was increased by 29.6% and citrinin concentration was reduced by 79.5%. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  18. Chipping and grinding production rate calculator

    Science.gov (United States)

    Mathew. Smidt; Dana Mitchell

    2014-01-01

    The data for individual chipper and grinder production estimates were recorded with all the attributes available. If a study provided more than one production estimate and there was sufficient detail to describe each estimate, we entered multiple production estimates.

  19. Changes in carbon storage and oxygen production in forest timber ...

    African Journals Online (AJOL)

    Decrease in forest areas world wide and the damaging of its structures is hazardous to human health, hinders and dries up the spread of oxygen in the air and also destroys carbon storage. In recent years, global warming and changes in climates depending on the increase in the green house gases have been affecting the ...

  20. Lunar Oxygen Production and Metals Extraction Using Ionic Liquids

    Science.gov (United States)

    Marone, Matthew; Paley, Mark Steven; Donovan, David N.; Karr, Laurel J.

    2009-01-01

    Initial results indicate that ionic liquids are promising media for the extraction of oxygen from lunar regolith. IL acid systems can solubilize regolith and produce water with high efficiency. IL electrolytes are effective for water electrolysis, and the spent IL acid media are capable of regeneration.

  1. Changes of heart rate variability and prefrontal oxygenation during Tai Chi practice versus arm ergometer cycling

    OpenAIRE

    Lu, Xi; Hui-Chan, Christina Wan-Ying; Tsang, William Wai-Nam

    2016-01-01

    [Purpose] Exercise has been shown to improve cardiovascular fitness and cognitive function. Whether the inclusion of mind over exercise would increase parasympathetic control of the heart and brain activities more than general exercise at a similar intensity is not known. The aim of this study was to compare the effects of Tai Chi (mind-body exercise) versus arm ergometer cycling (body-focused exercise) on the heart rate variability and prefrontal oxygenation level. [Subjects and Methods] A T...

  2. Fuzzy production planning models for an unreliable production system with fuzzy production rate and stochastic/fuzzy demand rate

    Directory of Open Access Journals (Sweden)

    K. A. Halim

    2011-01-01

    Full Text Available In this article, we consider a single-unit unreliable production system which produces a single item. During a production run, the production process may shift from the in-control state to the out-of-control state at any random time when it produces some defective items. The defective item production rate is assumed to be imprecise and is characterized by a trapezoidal fuzzy number. The production rate is proportional to the demand rate where the proportionality constant is taken to be a fuzzy number. Two production planning models are developed on the basis of fuzzy and stochastic demand patterns. The expected cost per unit time in the fuzzy sense is derived in each model and defuzzified by using the graded mean integration representation method. Numerical examples are provided to illustrate the optimal results of the proposed fuzzy models.

  3. Oxygen in the deep-sea: The challenge of maintaining uptake rates in a changing ocean

    Science.gov (United States)

    Hofmann, A. F.; Peltzer, E. T.; Brewer, P. G.

    2011-12-01

    Although focused on recently, ocean acidification is not the only effect of anthropogenic CO2 emissions on the ocean. Ocean warming will reduce dissolved oxygen concentrations and at the hypoxic limit for a given species this can pose challenges to marine life. The limit is traditionally reported simply as the static mass concentration property [O2]; here we treat it as a dynamic gas exchange problem for the animal analogous to gas exchange at the sea surface. The diffusive limit and its relationship to water velocity is critical for the earliest stages of marine life (eggs, embryos), but the effect is present for all animals at all stages of life. We calculate the external limiting O2 conditions for several representative metabolic rates and their relationship to flow of the bulk fluid under different environmental conditions. Ocean O2 concentrations decline by ≈ 14 μmol kg-1 for a 2 °C rise in temperature. At standard 1000 m depth conditions in the Pacific, flow over the surface would have to increase by ≈ 60% from 2.0 to 3.2 cm s-1 to compensate for this change. The functions derived allow new calculations of depth profiles of limiting O2 concentrations, as well as maximal diffusively sustainable metabolic oxygen consumption rates at various places around the world. Our treatment shows that there is a large variability in the global ocean in terms of facilitating aerobic life. This variability is greater than the variability of the oxygen concentration alone. It becomes clear that temperature and pressure dependencies of diffusion and partial pressure create a region typically around 1000 m depth where a maximal [O2] is needed to sustain a given metabolic rate. This zone of greatest physical constriction on the diffusive transport in the boundary layer is broadly consistent with the oxygen minimum zone, i.e., the zone of least oxygen concentration supply, resulting in a pronounced minimum of maximal diffusively sustainable metabolic oxygen consumption

  4. Islet Oxygen Consumption Rate (OCR) Dose Predicts Insulin Independence in Clinical Islet Autotransplantation.

    Science.gov (United States)

    Papas, Klearchos K; Bellin, Melena D; Sutherland, David E R; Suszynski, Thomas M; Kitzmann, Jennifer P; Avgoustiniatos, Efstathios S; Gruessner, Angelika C; Mueller, Kathryn R; Beilman, Gregory J; Balamurugan, Appakalai N; Loganathan, Gopalakrishnan; Colton, Clark K; Koulmanda, Maria; Weir, Gordon C; Wilhelm, Josh J; Qian, Dajun; Niland, Joyce C; Hering, Bernhard J

    2015-01-01

    Reliable in vitro islet quality assessment assays that can be performed routinely, prospectively, and are able to predict clinical transplant outcomes are needed. In this paper we present data on the utility of an assay based on cellular oxygen consumption rate (OCR) in predicting clinical islet autotransplant (IAT) insulin independence (II). IAT is an attractive model for evaluating characterization assays regarding their utility in predicting II due to an absence of confounding factors such as immune rejection and immunosuppressant toxicity. Membrane integrity staining (FDA/PI), OCR normalized to DNA (OCR/DNA), islet equivalent (IE) and OCR (viable IE) normalized to recipient body weight (IE dose and OCR dose), and OCR/DNA normalized to islet size index (ISI) were used to characterize autoislet preparations (n = 35). Correlation between pre-IAT islet product characteristics and II was determined using receiver operating characteristic analysis. Preparations that resulted in II had significantly higher OCR dose and IE dose (p<0.001). These islet characterization methods were highly correlated with II at 6-12 months post-IAT (area-under-the-curve (AUC) = 0.94 for IE dose and 0.96 for OCR dose). FDA/PI (AUC = 0.49) and OCR/DNA (AUC = 0.58) did not correlate with II. OCR/DNA/ISI may have some utility in predicting outcome (AUC = 0.72). Commonly used assays to determine whether a clinical islet preparation is of high quality prior to transplantation are greatly lacking in sensitivity and specificity. While IE dose is highly predictive, it does not take into account islet cell quality. OCR dose, which takes into consideration both islet cell quality and quantity, may enable a more accurate and prospective evaluation of clinical islet preparations.

  5. Islet Oxygen Consumption Rate (OCR Dose Predicts Insulin Independence in Clinical Islet Autotransplantation.

    Directory of Open Access Journals (Sweden)

    Klearchos K Papas

    Full Text Available Reliable in vitro islet quality assessment assays that can be performed routinely, prospectively, and are able to predict clinical transplant outcomes are needed. In this paper we present data on the utility of an assay based on cellular oxygen consumption rate (OCR in predicting clinical islet autotransplant (IAT insulin independence (II. IAT is an attractive model for evaluating characterization assays regarding their utility in predicting II due to an absence of confounding factors such as immune rejection and immunosuppressant toxicity.Membrane integrity staining (FDA/PI, OCR normalized to DNA (OCR/DNA, islet equivalent (IE and OCR (viable IE normalized to recipient body weight (IE dose and OCR dose, and OCR/DNA normalized to islet size index (ISI were used to characterize autoislet preparations (n = 35. Correlation between pre-IAT islet product characteristics and II was determined using receiver operating characteristic analysis.Preparations that resulted in II had significantly higher OCR dose and IE dose (p<0.001. These islet characterization methods were highly correlated with II at 6-12 months post-IAT (area-under-the-curve (AUC = 0.94 for IE dose and 0.96 for OCR dose. FDA/PI (AUC = 0.49 and OCR/DNA (AUC = 0.58 did not correlate with II. OCR/DNA/ISI may have some utility in predicting outcome (AUC = 0.72.Commonly used assays to determine whether a clinical islet preparation is of high quality prior to transplantation are greatly lacking in sensitivity and specificity. While IE dose is highly predictive, it does not take into account islet cell quality. OCR dose, which takes into consideration both islet cell quality and quantity, may enable a more accurate and prospective evaluation of clinical islet preparations.

  6. Photo-excitation of carotenoids causes cytotoxicity via singlet oxygen production

    International Nuclear Information System (INIS)

    Yoshii, Hiroshi; Yoshii, Yukie; Asai, Tatsuya; Furukawa, Takako; Takaichi, Shinichi; Fujibayashi, Yasuhisa

    2012-01-01

    Highlights: ► Some photo-excited carotenoids have photosensitizing ability. ► They are able to produce ROS. ► Photo-excited fucoxanthin can produce singlet oxygen through energy transfer. -- Abstract: Carotenoids, natural pigments widely distributed in algae and plants, have a conjugated double bond system. Their excitation energies are correlated with conjugation length. We hypothesized that carotenoids whose energy states are above the singlet excited state of oxygen (singlet oxygen) would possess photosensitizing properties. Here, we demonstrated that human skin melanoma (A375) cells are damaged through the photo-excitation of several carotenoids (neoxanthin, fucoxanthin and siphonaxanthin). In contrast, photo-excitation of carotenoids that possess energy states below that of singlet oxygen, such as β-carotene, lutein, loroxanthin and violaxanthin, did not enhance cell death. Production of reactive oxygen species (ROS) by photo-excited fucoxanthin or neoxanthin was confirmed using a reporter assay for ROS production with HeLa Hyper cells, which express a fluorescent indicator protein for intracellular ROS. Fucoxanthin and neoxanthin also showed high cellular penetration and retention. Electron spin resonance spectra using 2,2,6,6-tetramethil-4-piperidone as a singlet oxygen trapping agent demonstrated that singlet oxygen was produced via energy transfer from photo-excited fucoxanthin to oxygen molecules. These results suggest that carotenoids such as fucoxanthin, which are capable of singlet oxygen production through photo-excitation and show good penetration and retention in target cells, are useful as photosensitizers in photodynamic therapy for skin disease.

  7. Dielectronic recombination rate coefficients to excited states of Be-like oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Izumi; Safronova, Ulyana I.; Kato, Takako

    2001-05-01

    We have calculated energy levels, radiative transition probabilities, and autoionization rates for Be-like oxygen (O{sup 4+}) including ls{sup 2}2lnl' (n=2 - 8, l {<=} n - 1) and 1s{sup 2}3l'nl (n=3 - 6, l {<=} n - l) states by multi-configurational Hartree-Fock method (Cowan code) and perturbation theory Z-expansion method (MZ code). The state selective dielectronic recombination rate coefficients to excited states of Be-like O ions are obtained. Configuration mixing plays an important role for the principal quantum number n distribution of the dielectronic recombination rate coefficients for 2snl (n {<=} 5) levels at low electron temperature. The orbital angular momentum quantum number l distribution of the rate coefficients shows a peak at l = 4. The total dielectronic recombination rate coefficient is derived as a function of electron temperature. (author)

  8. Design of generic coal conversion facilities: Production of oxygenates from synthesis gas---A technology review

    Energy Technology Data Exchange (ETDEWEB)

    1991-10-01

    This report concentrates on the production of oxygenates from coal via gasification and indirect liquefaction. At the present the majority of oxygenate synthesis programs are at laboratory scale. Exceptions include commercial and demonstration scale plants for methanol and higher alcohols production, and ethers such as MTBE. Research and development work has concentrated on elucidating the fundamental transport and kinetic limitations governing various reactor configurations. But of equal or greater importance has been investigations into the optimal catalyst composition and process conditions for the production of various oxygenates.

  9. Lyoluminescence of irradiated carbohydrates - the role of dissolution rate and oxygen

    International Nuclear Information System (INIS)

    Baugh, P.J.; Laflin, P.

    1980-01-01

    The lyoluminescent emission from γ-irradiated carbohydrates is shown to be strictly controlled by the rate of dissolution of the solid and the availability of oxygen for reaction during dissolution. These effects are explained in terms of oxidation of trapped radicals diffusing from the dissolving carbohydrate which react in an 'active volume' set up at the onset of dissolution at the crystal-water interface. At irradiation doses greater than 82.5 krad for mannose there is a suppression of the emission which results from an incomplete oxidation of the diffusing radicals due to insufficient O 2 in the active volume leading to a reaction involving unoxidised radicals and peroxyl radicals which are believed to be the precursors of the emission. This reaction is suppressed when the oxygen supply to the 'active volume' is increased. This can be achieved by increasing the oxygen content of the injector gas and indirectly by decreasing the solubility of the carbohydrate. Under these conditions the linear dose range of the lyoluminescence response is extended to ca. 330 krad close to the dose at which trapped radicals saturate in the irradiated solid carbohydrate. Although lyoluminescence is a liquid surface-layer effect as expected the generation of the emission is greatly influenced by oxygen present in the injection atmosphere. Quenching of lyoluminescence by adding peroxyl radical quenchers Cu(II) ions and hydroquinone, suggests that the reaction involving these quenchers also occurs in the 'active volume'. The results generally can be interpreted in terms of a diffusion model. (author)

  10. Validation of the Nonin 8600V Pulse Oximeter for heart rate and oxygen saturation measurements in rats.

    Science.gov (United States)

    Bernard, Susan L; An, Dowon; Glenny, Robb W

    2004-05-01

    This report validates the use and limitations of the Nonin Pulse Oximeter for measuring heart rate and oxygen saturation in rats. Eight anesthetized Sprague-Dawley rats were intubated and catheterized. Oxygen saturation was directly measured from arterial blood by using a Radiometer OSM3 Hemoximeter adjusted for rat blood as well as indirectly by using the Nonin Pulse Oximeter. Oxygen saturation was changed by varying the level of inhaled oxygen. Heart rate was measured in two ways: 1) by using the signal from the Nonin Pulse Oximeter and 2) by counting the pressure pulses from the transduced blood pressure. There was excellent agreement between heart rate values measured by the Nonin Pulse Oximeter and that measured by counting the pulses from the arterial blood pressure recording. The Nonin Pulse Oximeter underestimated oxygen saturations by about 3% to 5% compared to the Hemoximeter. Overall, the pulse oximeter reflected important trends in oxygen saturations, making it a useful tool for laboratory animal medicine.

  11. Estimating primary production from oxygen time series: A novel approach in the frequency domain

    NARCIS (Netherlands)

    Cox, T.J.S.; Maris, T.; Soetaert, K.; Kromkamp, J.C.; Meire, P.; Meysman, F.J.R.

    2015-01-01

    Based on an analysis in the frequency domain of the governing equation of oxygen dynamics in aquatic systems, we derive a new method for estimating gross primary production (GPP) from oxygen time series. The central result of this article is a relation between time averaged GPP and the amplitude of

  12. Hydrogen sulfide oxidation without oxygen - oxidation products and pathways

    International Nuclear Information System (INIS)

    Fossing, H.

    1992-01-01

    Hydrogen sulfide oxidation was studied in anoxic marine sediments-both in undisturbed sediment cores and in sediment slurries. The turn over of hydrogen sulfide was followed using 35 S-radiolabeled hydrogen sulfide which was injected into the sediment. However, isotope exchange reactions between the reduced sulfur compounds, in particular between elemental sulfur and hydrogen sulfide, influenced on the specific radioactivity of these pools. It was, therefore, not possible to measure the turn over rates of the reduced sulfur pools by the radiotracer technique but merely to use the radioisotope to demonstrate some of the oxidation products. Thiosulfate was one important intermediate in the anoxic oxidation of hydrogen sulfide and was continuously turned over by reduction, oxidation and disproportionation. The author discusses the importance of isotope exchange and also presents the results from experiments in which both 35 S-radiolabeled elemental sulfur, radiolabeled hydrogen sulfide and radiolabeled thiosulfate were used to study the intermediates in the oxidative pathways of the sulfur cycle

  13. Reactive oxygen species production and discontinuous gas exchange in insects

    OpenAIRE

    Boardman, Leigh; Terblanche, John S.; Hetz, Stefan K.; Marais, Elrike; Chown, Steven L.

    2011-01-01

    While biochemical mechanisms are typically used by animals to reduce oxidative damage, insects are suspected to employ a higher organizational level, discontinuous gas exchange mechanism to do so. Using a combination of real-time, flow-through respirometry and live-cell fluorescence microscopy, we show that spiracular control associated with the discontinuous gas exchange cycle (DGC) in Samia cynthia pupae is related to reactive oxygen species (ROS). Hyperoxia fails to increase mean ROS produ...

  14. The Productivity of Oxygenic Photosynthesis around Cool, M Dwarf Stars

    Science.gov (United States)

    Lehmer, Owen R.; Catling, David C.; Parenteau, Mary N.; Hoehler, Tori M.

    2018-06-01

    In the search for life around cool stars, the presence of atmospheric oxygen is a prominent biosignature, as it may indicate oxygenic photosynthesis (OP) on the planetary surface. On Earth, most oxygenic photosynthesizing organisms (OPOs) use photons between 400 and 750 nm, which have sufficient energy to drive the photosynthetic reaction that generates O2 from H2O and CO2. OPOs around cool stars may evolve similar biological machinery capable of producing oxygen from water. However, in the habitable zones (HZs) of the coolest M dwarf stars, the flux of 400–750 nm photons may be just a few percent that of Earth’s. We show that the reduced flux of 400–750 nm photons around M dwarf stars could result in Earth-like planets being growth limited by light, unlike the terrestrial biosphere, which is limited by nutrient availability. We consider stars with photospheric temperatures between 2300 and 4200 K and show that such light-limited worlds could occur at the outer edge of the HZ around TRAPPIST-1-like stars. We find that even if OP can use photons longer than 750 nm, there would still be insufficient energy to sustain the Earth’s extant biosphere throughout the HZ of the coolest stars. This is because such stars emit largely in the infrared and near-infrared, which provide sufficient energy to make the planet habitable, but limits the energy available for OP. TRAPPIST-1f and g may fall into this category. Biospheres on such planets, potentially limited by photon availability, may generate small biogenic signals, which could be difficult for future observations to detect.

  15. Incremental rate of prefrontal oxygenation determines performance speed during cognitive Stroop test: the effect of ageing.

    Science.gov (United States)

    Endo, Kana; Liang, Nan; Idesako, Mitsuhiro; Ishii, Kei; Matsukawa, Kanji

    2018-02-19

    Cognitive function declines with age. The underlying mechanisms responsible for the deterioration of cognitive performance, however, remain poorly understood. We hypothesized that an incremental rate of prefrontal oxygenation during a cognitive Stroop test decreases in progress of ageing, resulting in a slowdown of cognitive performance. To test this hypothesis, we identified, using multichannel near-infrared spectroscopy, the characteristics of the oxygenated-hemoglobin concentration (Oxy-Hb) responses of the prefrontal cortex to both incongruent Stroop and congruent word-reading test. Spatial distributions of the significant changes in the three components (initial slope, peak amplitude, and area under the curve) of the Oxy-Hb response were compared between young and elderly subjects. The Stroop interference time (as a difference in total periods for executing Stroop and word-reading test, respectively) approximately doubled in elderly as compared to young subjects. The Oxy-Hb in the rostrolateral, but not caudal, prefrontal cortex increased during the Stroop test in both age groups. The initial slope of the Oxy-Hb response, rather than the peak and area under the curve, had a strong correlation with cognitive performance speed. Taken together, it is likely that the incremental rate of prefrontal oxygenation may decrease in progress of ageing, resulting in a decline in cognitive performance.

  16. The role of oxygen and water on molybdenum nanoclusters for electro catalytic ammonia production

    Directory of Open Access Journals (Sweden)

    Jakob G. Howalt

    2014-01-01

    Full Text Available The presence of water often gives rise to oxygen adsorption on catalyst surfaces through decomposition of water and the adsorbed oxygen or hydroxide species often occupy important surfaces sites, resulting in a decrease or a total hindrance of other chemical reactions taking place at that site. In this study, we present theoretical investigations of the influence of oxygen adsorption and reduction on pure and nitrogen covered molybdenum nanocluster electro catalysts for electrochemical reduction of N2 to NH3 with the purpose of understanding oxygen and water poisoning of the catalyst. Density functional theory calculations are used in combination with the computational hydrogen electrode approach to calculate the free energy profile for electrochemical protonation of O and N2 species on cuboctahedral Mo13 nanoclusters. The calculations show that the molybdenum nanocluster will preferentially bind oxygen over nitrogen and hydrogen at neutral bias, but under electrochemical reaction conditions needed for nitrogen reduction, oxygen adsorption is severely weakened and the adsorption energy is comparable to hydrogen and nitrogen adsorption. The potentials required to reduce oxygen off the surface are −0.72 V or lower for all oxygen coverages studied, and it is thus possible to (reactivate (partially oxidized nanoclusters for electrochemical ammonia production, e.g., using a dry proton conductor or an aqueous electrolyte. At lower oxygen coverages, nitrogen molecules can adsorb to the surface and electrochemical ammonia production via the associative mechanism is possible at potentials as low as −0.45 V to −0.7 V.

  17. Solar light-induced production of reactive oxygen species by single walled carbon nanotubes in water

    Science.gov (United States)

    Photosensitizing processes of engineered nanomaterials (ENMs) which include photo-induced production of reactive oxygen species (ROS) convert light energy into oxidizing chemical energy that mediates transformations of nanomaterials. The oxidative stress associated with ROS may p...

  18. The slope of the oxygen pulse curve does not depend on the maximal heart rate in elite soccer players

    Directory of Open Access Journals (Sweden)

    Raphael Rodrigues Perim

    2011-01-01

    Full Text Available INTRODUCTION: It is unknown whether an extremely high heart rate can affect oxygen pulse profile during progressive maximal exercise in healthy subjects. OBJECTIVE: Our aim was to compare relative oxygen pulse (adjusted for body weight curves in athletes at their maximal heart rate during treadmill cardiopulmonary exercise testing. METHODS: A total of 180 elite soccer players were categorized in quartiles according to their maximum heart rate values (n = 45. Oxygen consumption, maximum heart rate and relative oxygen pulse curves in the extreme quartiles, Q1 and Q4, were compared at intervals corresponding to 10% of the total duration of a cardiopulmonary exercise testing. RESULTS: Oxygen consumption was similar among all subjects during cardiopulmonary exercise testing; however subjects in Q1 started to exhibit lower maximum heart rate values when 20% of the test was complete. Conversely, the relative oxygen pulse was higher in this group when cardiopulmonary exercise testing was 40% complete (p<.01. Although the slopes of the lines were similar (p = .25, the regression intercepts differed (p<.01 between Q1 and Q4. During the last two minutes of testing, a flat or decreasing oxygen pulse was identified in 20% of the soccer players, and this trend was similar between subjects in Q1 and Q4. CONCLUSION: Relative oxygen pulse curve slopes, which serve as an indirect and non-invasive surrogate for stroke volume, suggest that the stroke volume is similar in young and aerobically fit subjects regardless of the maximum heart rate reached.

  19. Association of apneic oxygenation with decreased desaturation rates during rapid sequence intubation by a Chinese emergency medicine service.

    Science.gov (United States)

    Mao, Yong; Qin, Zong-He

    2015-01-01

    Rapid and safe airway management has always been of paramount importance in successful management of critically ill and injured patients in the emergency department. The achievement rate of emergency medicine inhabitants in airway management improved enhanced essentially subsequent to finishing anaesthesiology turn. There was a slightly higher rate of quick sequence intubation in the postapneic oxygenation groups (preapneic oxygenation 6.4%; postapneic oxygenation 9.1%). The majority of patients intubated in both groups were men (preapneic oxygenation 72.3%; postapneic oxygenation 63.5%). A higher percentage of patients in the preapneic oxygenation group had a Cormack-Lehane grade III or worse view (23.2% versus 11.8%). Anaesthesiology turns should be considered as an essential component of emergency medicine training programs. A collateral curriculum of this nature should also focus on the acquisition of skills in airway management.

  20. Using rates of oxygen and nitrate reduction to map the subsurface distribution of groundwater denitrification

    Science.gov (United States)

    Kolbe, T.; De Dreuzy, J. R.; Abbott, B. W.; Aquilina, L.; Babey, T.; Green, C. T.; Fleckenstein, J. H.; Labasque, T.; Laverman, A.; Marçais, J.; Peiffer, S.; Thomas, Z.; Pinay, G.

    2017-12-01

    Widespread fertilizer application over the last 70 years has caused serious ecological and socioeconomic problems in aquatic and estuarine ecosystems. When surplus nitrogen leaches as nitrate (a major groundwater pollutant) to the aquifer, complex flow dynamics and naturally occurring degradation processes control its transport. Under the conditions of depleted oxygen and abundant electron donors, microorganisms reduce NO3- to N2 (denitrification). Denitrification rates vary over orders of magnitude among sites within the same aquifer, complicating estimation of denitrification capacity at the catchment scale. Because it is impractical or impossible to access the subsurface to directly quantify denitrification rates, reactivity is often assumed to occur continuous along flowlines, potentially resulting in substantial over- or underestimation of denitrification. Here we investigated denitrification in an unconfined crystalline aquifer in western France using a combination of common tracers (chlorofluorocarbons, O2, NO3-, and N2) measured in 16 wells to inform a time-based modeling approach. We found that spatially variable denitrification rates arise from the intersection of nitrate rich water with reactive zones defined by the abundance of electron donors (primarily pyrite). Furthermore, based on observed reaction rates of the sequential reduction of oxygen and nitrate, we present a general framework to estimate the location and intensity of the reactive zone in aquifers. Accounting for the vertical distribution of reaction rates results in large differences in estimations of net denitrification rates that assume homogeneous reactivity. This new framework provides a tractable approach for quantifying catchment and regional groundwater denitrification rates that could be used to improve estimation of groundwater resilience to nitrate pollution and develop more realistic management strategies.

  1. With medium-chain triglycerides, higher and faster oxygen radical production by stimulated polymorphonuclear leukocytes occurs.

    Science.gov (United States)

    Kruimel, J W; Naber, A H; Curfs, J H; Wenker, M A; Jansen, J B

    2000-01-01

    Parenteral lipid emulsions are suspected of suppressing the immune function. However, study results are contradictory and mainly concern the conventional long-chain triglyceride emulsions. Polymorphonuclear leukocytes were preincubated with parenteral lipid emulsions. The influence of the lipid emulsions on the production of oxygen radicals by these stimulated leukocytes was studied by measuring chemiluminescence. Three different parenteral lipid emulsions were tested: long-chain triglycerides, a physical mixture of medium- and long-chain triglycerides, and structured triglycerides. Structured triglycerides consist of triglycerides where the medium- and long-chain fatty acids are attached to the same glycerol molecule. Stimulated polymorphonuclear leukocytes preincubated with the physical mixture of medium- and long-chain triglycerides showed higher levels of oxygen radicals (p triglycerides or structured triglycerides. Additional studies indicated that differences in results of various lipid emulsions were not caused by differences in emulsifier. The overall production of oxygen radicals was significantly lower after preincubation with the three lipid emulsions compared with controls without lipid emulsion. A physical mixture of medium- and long-chain triglycerides induced faster production of oxygen radicals, resulting in higher levels of oxygen radicals, compared with long-chain triglycerides or structured triglycerides. This can be detrimental in cases where oxygen radicals play either a pathogenic role or a beneficial one, such as when rapid phagocytosis and killing of bacteria is needed. The observed lower production of oxygen radicals by polymorphonuclear leukocytes in the presence of parenteral lipid emulsions may result in immunosuppression by these lipids.

  2. The relationship between body temperature, heart rate, breathing rate, and rate of oxygen consumption, in the tegu lizard (Tupinambis merianae) at various levels of activity.

    Science.gov (United States)

    Piercy, Joanna; Rogers, Kip; Reichert, Michelle; Andrade, Denis V; Abe, Augusto S; Tattersall, Glenn J; Milsom, William K

    2015-12-01

    The present study determined whether EEG and/or EMG recordings could be used to reliably define activity states in the Brazilian black and white tegu lizard (Tupinambis merianae) and then examined the interactive effects of temperature and activity states on strategies for matching O2 supply and demand. In a first series of experiments, the rate of oxygen consumption (VO2), breathing frequency (fR), heart rate (fH), and EEG and EMG (neck muscle) activity were measured in different sleep/wake states (sleeping, awake but quiet, alert, or moving). In general, metabolic and cardio-respiratory changes were better indictors of the transition from sleep to wake than were changes in the EEG and EMG. In a second series of experiments, the interactive effects of temperature (17, 27 and 37 °C) and activity states on fR, tidal volume (VT), the fraction of oxygen extracted from the lung per breath (FIO2-FEO2), fH, and the cardiac O2 pulse were quantified to determine the relative roles of each of these variables in accommodating changes in VO2. The increases in oxygen supply to meet temperature- and activity-induced increases in oxygen demand were produced almost exclusively by increases in fH and fR. Regression analysis showed that the effects of temperature and activity state on the relationships between fH, fR and VO2 was to extend a common relationship along a single curve, rather than separate relationships for each metabolic state. For these lizards, the predictive powers of fR and fH were maximized when the effects of changes in temperature, digestive state and activity were pooled. However, the best r(2) values obtained were 0.63 and 0.74 using fR and fH as predictors of metabolic rate, respectively.

  3. Fermentation process using specific oxygen uptake rates as a process control

    Science.gov (United States)

    Van Hoek, Pim [Minnetonka, MN; Aristidou, Aristos [Maple Grove, MN; Rush, Brian [Minneapolis, MN

    2011-05-10

    Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

  4. Sperm Production Rate, Gonadal and Extragonadal Sperm ...

    African Journals Online (AJOL)

    Five healthy West African Dwarf (WAD) rams, 1.5 to 2.5 years of age and weighing between 15 kg to 20 kg were used to determine daily sperm production, gonadal and exragonadal sperm reserves. Gonadal and extragonadal sperm reserves were estimated by the haemocytometric method, while the daily sperm production ...

  5. Influence of Prolonged Spaceflight on Heart Rate and Oxygen Uptake Kinetics

    Science.gov (United States)

    Hoffmann, U.; Moore, A.; Drescher, U.

    2013-02-01

    During prolonged spaceflight, physical training is used to minimize cardiovascular deconditioning. Measurement of the kinetics of cardiorespiratory parameters, in particular the kinetic analysis of heart rate, respiratory and muscular oxygen uptake, provides useful information with regard to the efficiency and regulation of the cardiorespiratory system. Practically, oxygen uptake kinetics can only be measured at the lung site (V’O2 resp). The dynamics of V’O2 resp, however, is not identical with the dynamics at the site of interest: skeletal muscle. Eight Astronauts were tested pre- and post-flight using pseudo random binary workload changes between 30 and 80 W. Their kinetic responses of heart rate, respiratory as well as muscular V’O2 kinetics were estimated by using time-series analysis. Statistical analysis revealed that the kinetic responses of respiratory as well as muscular V’O2 kinetics are slowed post-flight than pre-flight. Heart rate seems not to be influenced following flight. The influence of other factors (e. g. astronauts’ exercise training) may impact these parameters and is an area for future studies.

  6. 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.

  7. Molecular Tuning of Phenylene-Vinylene Derivatives for Two-Photon Photosensitized Singlet Oxygen Production

    DEFF Research Database (Denmark)

    Nielsen, Christian B.; Arnbjerg, Jacob; Johnsen, Mette

    2009-01-01

    Substituent-dependent features and properties of the sensitizer play an important role in the photosensitized production of singlet oxygen, O2(a1Δg). In this work, we systematically examine the effect of molecular changes in the sensitizer on the efficiency of singlet oxygen production using......, as the sensitizer, oligophenylene-vinylene derivatives designed to optimally absorb light in a nonlinear two-photon process. We demonstrate that one cannot always rely on rule-of-thumb guidelines when attempting to construct efficient two-photon singlet oxygen sensitizers. Rather, as a consequence of behavior...... that can deviate from the norm, a full investigation of the photophysical properties of the system is generally required. For example, it is acknowledged that the introduction of a ketone moiety to the sensitizer chromophore often results in more efficient production of singlet oxygen. However, we show...

  8. The F-16 Onboard Oxygen Generating System: Performance Evaluation and Man Rating

    Science.gov (United States)

    1983-08-01

    OXYGEN GENERATING , YSTEM: PERFORMANCE EVALUATION AND MAN RATING Thomas C. Horch , Captain, USAF Richard L. Miller, Ph.D. John B. Bomar, Jr...C. Horch , Capt, USAF; R. L. Miller, 8. CONTRACT OR GRANT NUMBER(i) Ph.D.; J. B. Bomar, Jr., Lt Col, IJSAF, BSC; J. B. Tedor, Maj, USAF, BSC; R. D...limitation (as of 1983); however, the information may no longer need protection since it is 14 years. At the time of its publication, Capt Thomas Horch

  9. Oxygen consumption and mortality rate of mice after X radiation under the influence of magnetic fields

    International Nuclear Information System (INIS)

    Rekbi, M.

    1984-01-01

    In this work it was studied whether an influence on the oxygen use was to be expected as a result of a magnetic pulsating field. This could not be determined. An increased effect of the magnetic field with respect to the reduction of the mortality rate was, however, to be observed. Thereby the influence of similar constant and pulsating fields was discussed from various perspectives. The question of the biological effect mechanism of the magnetic field (main issue of the influence of the magnetic field during or after the irradiation) can only be answered by further comprehensive investigations. (orig./MG) [de

  10. Influence of Vitamins on Secondary Reactive Oxygen Species Production in Sera of Patients with Resectable NSCLC

    Directory of Open Access Journals (Sweden)

    Thierry Patrice

    2016-07-01

    Full Text Available Background: Singlet oxygen (1O2 oxidizes targets through the production of secondary reactive oxygen species (SOS. Cancers induce oxidative stress changing with progression, the resulting antioxidant status differing from one patient to the other. The aim of this study was to determine the oxidative status of patients with resectable Non-Small cell lung cancers (NSCLC and the potential influence of antioxidants, compared to sera from healthy donors. Materials and Methods: Serum samples from 10 women and 28 men, 19 adenocarcinomas (ADK, 15 patients N1 or M1 were submitted to a photoreaction producing 1O2. Then, samples were supplemented with vitamins (Vit C, Vit E, or glutathione (GSH. Results: Squamous cell carcinomas (SCC and metastatic SCCs induced a lower SOS rate. While Vit C increased SOS in controls as in patients with metastases, Vit E or the combination of Vit E and C strongly reduced SOS. GSH alone lightly decreased SOS in controls but had no effect in patients either alone or combined with Vit C. Conclusion: In “early” lung cancers, SOS are comparable or lower than for healthy persons. The role of Vitamins varies with gender, cancer type, and metastases. This suggests that an eventual supplementation should be performed on a per-patient basis to evidence any effect.

  11. Fetal programming alters reactive oxygen species production in sheep cardiac mitochondria.

    Science.gov (United States)

    von Bergen, Nicholas H; Koppenhafer, Stacia L; Spitz, Douglas R; Volk, Kenneth A; Patel, Sonali S; Roghair, Robert D; Lamb, Fred S; Segar, Jeffrey L; Scholz, Thomas D

    2009-04-01

    Exposure to an adverse intrauterine environment is recognized as an important risk factor for the development of cardiovascular disease later in life. Although oxidative stress has been proposed as a mechanism for the fetal programming phenotype, the role of mitochondrial O(2)(*-) (superoxide radical) production has not been explored. To determine whether mitochondrial ROS (reactive oxygen species) production is altered by in utero programming, pregnant ewes were given a 48-h dexamethasone (dexamethasone-exposed, 0.28 mg.kg(-1) of body weight.day(-1)) or saline (control) infusion at 27-28 days gestation (term=145 days). Intact left ventricular mitochondria and freeze-thaw mitochondrial membranes were studied from offspring at 4-months of age. AmplexRed was used to measure H(2)O(2) production. Activities of the antioxidant enzymes Mn-SOD (manganese superoxide dismutase), GPx (glutathione peroxidase) and catalase were measured. Compared with controls, a significant increase in Complex I H(2)O(2) production was found in intact mitochondria from dexamethasone-exposed animals. The treatment differences in Complex I-driven H(2)O(2) production were not seen in mitochondrial membranes. Consistent changes in H(2)O(2) production from Complex III in programmed animals were not found. Despite the increase in H(2)O(2) production in intact mitochondria from programmed animals, dexamethasone exposure significantly increased mitochondrial catalase activity, whereas Mn-SOD and GPx activities were unchanged. The results of the present study point to an increase in the rate of release of H(2)O(2) from programmed mitochondria despite an increase in catalase activity. Greater mitochondrial H(2)O(2) release into the cell may play a role in the development of adult disease following exposure to an adverse intrauterine environment.

  12. Real Exchange Rate and Productivity in an OLG Model

    OpenAIRE

    Thi Hong Thinh DOAN; Karine GENTE

    2013-01-01

    This article develops an overlapping generations model to show how demography and savings affect the relationship between real exchange rate (RER) and productivity. In high-saving (low-saving) countries and/or low-population-growth-rate countries, a rise in productivity leads to a real depreciation (appreciation) whereas the RER may appreciate or depreciate in highproduction-growth-rate. Using panel data, we conclude that a rise in productivity generally causes a real exchange rate appreciati...

  13. Topology and immersion depth of an integral membrane protein by paramagnetic rates from dissolved oxygen.

    Science.gov (United States)

    Al-Abdul-Wahid, M Sameer; Verardi, Raffaello; Veglia, Gianluigi; Prosser, R Scott

    2011-09-01

    In studies of membrane proteins, knowledge of protein topology can provide useful insight into both structure and function. In this work, we present a solution NMR method for the measurement the tilt angle and average immersion depth of alpha helices in membrane proteins, from analysis of the paramagnetic relaxation rate enhancements arising from dissolved oxygen. No modification to the micelle or protein is necessary, and the topology of both transmembrane and amphipathic helices are readily determined. We apply this method to the measure the topology of a monomeric mutant of phospholamban (AFA-PLN), a 52-residue membrane protein containing both an amphipathic and a transmembrane alpha helix. In dodecylphosphocholine micelles, the amphipathic helix of AFA-PLN was found to have a tilt angle of 87° ± 1° and an average immersion depth of 13.2 Å. The transmembrane helix was found to have an average immersion depth of 5.4 Å, indicating residues 41 and 42 are closest to the micelle centre. The resolution of paramagnetic relaxation rate enhancements from dissolved oxygen compares favourably to those from Ni (II), a hydrophilic paramagnetic species.

  14. Topology and immersion depth of an integral membrane protein by paramagnetic rates from dissolved oxygen

    International Nuclear Information System (INIS)

    Al-Abdul-Wahid, M. Sameer; Verardi, Raffaello; Veglia, Gianluigi; Prosser, R. Scott

    2011-01-01

    In studies of membrane proteins, knowledge of protein topology can provide useful insight into both structure and function. In this work, we present a solution NMR method for the measurement the tilt angle and average immersion depth of alpha helices in membrane proteins, from analysis of the paramagnetic relaxation rate enhancements arising from dissolved oxygen. No modification to the micelle or protein is necessary, and the topology of both transmembrane and amphipathic helices are readily determined. We apply this method to the measure the topology of a monomeric mutant of phospholamban (AFA-PLN), a 52-residue membrane protein containing both an amphipathic and a transmembrane alpha helix. In dodecylphosphocholine micelles, the amphipathic helix of AFA-PLN was found to have a tilt angle of 87° ± 1° and an average immersion depth of 13.2 Å. The transmembrane helix was found to have an average immersion depth of 5.4 Å, indicating residues 41 and 42 are closest to the micelle centre. The resolution of paramagnetic relaxation rate enhancements from dissolved oxygen compares favourably to those from Ni (II), a hydrophilic paramagnetic species.

  15. Oxygen activation at the plasma membrane: relation between superoxide and hydroxyl radical production by isolated membranes.

    Science.gov (United States)

    Heyno, Eiri; Mary, Véronique; Schopfer, Peter; Krieger-Liszkay, Anja

    2011-07-01

    Production of reactive oxygen species (hydroxyl radicals, superoxide radicals and hydrogen peroxide) was studied using EPR spin-trapping techniques and specific dyes in isolated plasma membranes from the growing and the non-growing zones of hypocotyls and roots of etiolated soybean seedlings as well as coleoptiles and roots of etiolated maize seedlings. NAD(P)H mediated the production of superoxide in all plasma membrane samples. Hydroxyl radicals were only produced by the membranes of the hypocotyl growing zone when a Fenton catalyst (FeEDTA) was present. By contrast, in membranes from other parts of the seedlings a low rate of spontaneous hydroxyl radical formation was observed due to the presence of small amounts of tightly bound peroxidase. It is concluded that apoplastic hydroxyl radical generation depends fully, or for the most part, on peroxidase localized in the cell wall. In soybean plasma membranes from the growing zone of the hypocotyl pharmacological tests showed that the superoxide production could potentially be attributed to the action of at least two enzymes, an NADPH oxidase and, in the presence of menadione, a quinone reductase.

  16. Value of cerebral blood flow rate and regional oxygen consumption studies in cerebral ischaemia

    Energy Technology Data Exchange (ETDEWEB)

    Clanet, M

    1987-06-18

    Studies of experimentally-induced ischaemia have shown that the intensity of neuronal suffering is related to the fall in perfusion rate. Below a certain level, called functional threshold, cerebral function is reversibly altered, whereas at a lower level (tissue necrosis threshold) the damage inflicted on neurons is irreversible. Between these two thresholds lies a ''penumbra zone''. This concept of thresholds must be mitigated by 2 parameters: duration of ischaemia and selective vulnerability of the various structures affected. Variations in blood flow rate only indirectly affect the state of tissues. Techniques developed from positron emission tomography make it possible to evaluate the metabolic activity of brain tissue in vivo: oxygen consumption (CMRO/sub 2/), oxygen extraction (EO/sub 2/) and glucose consumption (CMRG) which are thus correlated to cerebral blood flow and cerebral blood volume, sometimes also to tissue pH. Normal relations between blood flow rate and metabolism may be altered. Misery perfusion reflects a fall in cerebral blood flow with an increase in EO/sub 2/ and often a decrease in CMRO/sub 2/, whereas luxury perfusion reflects an increase in cerebral blood flow rate with reduction of CMRO/sub 2/, EO/sub 2/ and CMRG. The type of alteration encountered in human ischaemia varies according to the nature of the accident: studies of transient accidents emphasize the different haemodynamic aspects of occlusion of the wider arteries. The metabolic and haemodynamic profiles of established ischaemic accidents vary according to their type and to the time of the study, reflecting the complexity of the physiopathological mechanisms involved; they are frequently associated with metabolic repercussions at a distance from the ischaemic focus, which supports the concept of diaschisis.

  17. Value of cerebral blood flow rate and regional oxygen consumption studies in cerebral ischaemia

    International Nuclear Information System (INIS)

    Clanet, M.

    1987-01-01

    Studies of experimentally-induced ischaemia have shown that the intensity of neuronal suffering is related to the fall in perfusion rate. Below a certain level, called functional threshold, cerebral function is reversibly altered, whereas at a lower level (tissue necrosis threshold) the damage inflicted on neurons is irreversible. Between these two thresholds lies a ''penumbra zone''. This concept of thresholds must be mitigated by 2 parameters: duration of ischaemia and selective vulnerability of the various structures affected. Variations in blood flow rate only indirectly affect the state of tissues. Techniques developed from positron emission tomography make it possible to evaluate the metabolic activity of brain tissue in vivo: oxygen consumption (CMRO 2 ), oxygen extraction (EO 2 ) and glucose consumption (CMRG) which are thus correlated to cerebral blood flow and cerebral blood volume, sometimes also to tissue pH. Normal relations between blood flow rate and metabolism may be altered. Misery perfusion reflects a fall in cerebral blood flow with an increase in EO 2 and often a decrease in CMRO 2 , whereas luxury perfusion reflects an increase in cerebral blood flow rate with reduction of CMRO 2 , EO 2 and CMRG. The type of alteration encountered in human ischaemia varies according to the nature of the accident: studies of transient accidents emphasize the different haemodynamic aspects of occlusion of the wider arteries. The metabolic and haemodynamic profiles of established ischaemic accidents vary according to their type and to the time of the study, reflecting the complexity of the physiopathological mechanisms involved; they are frequently associated with metabolic repercussions at a distance from the ischaemic focus, which supports the concept of diaschisis [fr

  18. Analysis of heart rate and oxygen uptake kinetics studied by two different pseudo-random binary sequence work rate amplitudes.

    Science.gov (United States)

    Drescher, U; Koschate, J; Schiffer, T; Schneider, S; Hoffmann, U

    2017-06-01

    The aim of the study was to compare the kinetics responses of heart rate (HR), pulmonary (V˙O 2 pulm) and predicted muscular (V˙O 2 musc) oxygen uptake between two different pseudo-random binary sequence (PRBS) work rate (WR) amplitudes both below anaerobic threshold. Eight healthy individuals performed two PRBS WR protocols implying changes between 30W and 80W and between 30W and 110W. HR and V˙O 2 pulm were measured beat-to-beat and breath-by-breath, respectively. V˙O 2 musc was estimated applying the approach of Hoffmann et al. (Eur J Appl Physiol 113: 1745-1754, 2013) considering a circulatory model for venous return and cross-correlation functions (CCF) for the kinetics analysis. HR and V˙O 2 musc kinetics seem to be independent of WR intensity (p>0.05). V˙O 2 pulm kinetics show prominent differences in the lag of the CCF maximum (39±9s; 31±4s; p<0.05). A mean difference of 14W between the PRBS WR amplitudes impacts venous return significantly, while HR and V˙O 2 musc kinetics remain unchanged. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Conversion rate of para-hydrogen to ortho-hydrogen by oxygen: implications for PHIP gas storage and utilization.

    Science.gov (United States)

    Wagner, Shawn

    2014-06-01

    To determine the storability of para-hydrogen before reestablishment of the room temperature thermal equilibrium mixture. Para-hydrogen was produced at near 100% purity and mixed with different oxygen quantities to determine the rate of conversion to the thermal equilibrium mixture of 75: 25% (ortho: para) by detecting the ortho-hydrogen (1)H nuclear magnetic resonance using a 9.4 T imager. The para-hydrogen to ortho-hydrogen velocity constant, k, near room temperature (292 K) was determined to be 8.27 ± 1.30 L/mol · min(-1). This value was calculated utilizing four different oxygen fractions. Para-hydrogen conversion to ortho-hydrogen by oxygen can be minimized for long term storage with judicious removal of oxygen contamination. Prior calculated velocity rates were confirmed demonstrating a dependence on only the oxygen concentration.

  20. The role of oxygen and water on molybdenum nanoclusters for electro catalytic ammonia production

    DEFF Research Database (Denmark)

    Howalt, Jakob Geelmuyden; Vegge, Tejs

    2014-01-01

    are -0.72 V or lower for all oxygen coverages studied, and it is thus possible to (re)activate (partially) oxidized nanoclusters for electrochemical ammonia production, e.g., using a dry proton conductor or an aqueous electrolyte. At lower oxygen coverages, nitrogen molecules can adsorb to the surface...... and electrochemical ammonia production via the associative mechanism is possible at potentials as low as -0.45 V to -0.7 V. © 2014 Howalt and Vegge........ In this study, we present theoretical investigations of the influence of oxygen adsorption and reduction on pure and nitrogen covered molybdenum nanocluster electro catalysts for electrochemical reduction of N2 to NH3 with the purpose of understanding oxygen and water poisoning of the catalyst. Density...

  1. Production of sensitivity and false alarm rate

    International Nuclear Information System (INIS)

    Han Zijie; Kang Wu; Chu Chengsheng; Hao Fanhua; Liu Xiaoya; Cao Lin; Hu Yongbo; Gong Jian; Xiang Yongchun; Zhang Jianhua; Yang Xiangdong

    2007-01-01

    The false alarm rate and sensitivity in nuclear material monitoring system are affected by alarm principle. Two different alarm principles are studied with theory and experiment analysis in this paper. Our research shows that theory analysis and experiment result are accordant very much. This study provides technology support for designing better alarm principle in nuclear material monitoring system. (authors)

  2. Oxygen at nanomolar levels reversibly suppresses process rates and gene expression in anammox and denitrification in the oxygen minimum zone off northern Chile.

    Science.gov (United States)

    Dalsgaard, Tage; Stewart, Frank J; Thamdrup, Bo; De Brabandere, Loreto; Revsbech, Niels Peter; Ulloa, Osvaldo; Canfield, Don E; DeLong, Edward F

    2014-10-28

    A major percentage (20 to 40%) of global marine fixed-nitrogen loss occurs in oxygen minimum zones (OMZs). Concentrations of O2 and the sensitivity of the anaerobic N2-producing processes of anammox and denitrification determine where this loss occurs. We studied experimentally how O2 at nanomolar levels affects anammox and denitrification rates and the transcription of nitrogen cycle genes in the anoxic OMZ off Chile. Rates of anammox and denitrification were reversibly suppressed, most likely at the enzyme level. Fifty percent inhibition of N2 and N2O production by denitrification was achieved at 205 and 297 nM O2, respectively, whereas anammox was 50% inhibited at 886 nM O2. Coupled metatranscriptomic analysis revealed that transcripts encoding nitrous oxide reductase (nosZ), nitrite reductase (nirS), and nitric oxide reductase (norB) decreased in relative abundance above 200 nM O2. This O2 concentration did not suppress the transcription of other dissimilatory nitrogen cycle genes, including nitrate reductase (narG), hydrazine oxidoreductase (hzo), and nitrite reductase (nirK). However, taxonomic characterization of transcripts suggested inhibition of narG transcription in gammaproteobacteria, whereas the transcription of anammox narG, whose gene product is likely used to oxidatively replenish electrons for carbon fixation, was not inhibited. The taxonomic composition of transcripts differed among denitrification enzymes, suggesting that distinct groups of microorganisms mediate different steps of denitrification. Sulfide addition (1 µM) did not affect anammox or O2 inhibition kinetics but strongly stimulated N2O production by denitrification. These results identify new O2 thresholds for delimiting marine nitrogen loss and highlight the utility of integrating biogeochemical and metatranscriptomic analyses. The removal of fixed nitrogen via anammox and denitrification associated with low O2 concentrations in oceanic oxygen minimum zones (OMZ) is a major sink in

  3. 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, ...

  4. Biomarkers’ Responses to Reductive Dechlorination Rates and Oxygen Stress in Bioaugmentation Culture KB-1TM

    Directory of Open Access Journals (Sweden)

    Gretchen L. W. Heavner

    2018-02-01

    Full Text Available Using mRNA transcript levels for key functional enzymes as proxies for the organohalide respiration (OHR rate, is a promising approach for monitoring bioremediation populations in situ at chlorinated solvent-contaminated field sites. However, to date, no correlations have been empirically derived for chlorinated solvent respiring, Dehalococcoides mccartyi (DMC containing, bioaugmentation cultures. In the current study, genome-wide transcriptome and proteome data were first used to confirm the most highly expressed OHR-related enzymes in the bioaugmentation culture, KB-1TM, including several reductive dehalogenases (RDases and a Ni-Fe hydrogenase, Hup. Different KB-1™ DMC strains could be resolved at the RNA and protein level through differences in the sequence of a common RDase (DET1545-like homologs and differences in expression of their vinyl chloride-respiring RDases. The dominant strain expresses VcrA, whereas the minor strain utilizes BvcA. We then used quantitative reverse-transcriptase PCR (qRT-PCR as a targeted approach for quantifying transcript copies in the KB-1TM consortium operated under a range of TCE respiration rates in continuously-fed, pseudo-steady-state reactors. These candidate biomarkers from KB-1TM demonstrated a variety of trends in terms of transcript abundance as a function of respiration rate over the range: 7.7 × 10−12 to 5.9 × 10−10 microelectron equivalents per cell per hour (μeeq/cell∙h. Power law trends were observed between the respiration rate and transcript abundance for the main DMC RDase (VcrA and the hydrogenase HupL (R2 = 0.83 and 0.88, respectively, but not transcripts for 16S rRNA or three other RDases examined: TceA, BvcA or the RDase DET1545 homologs in KB1TM. Overall, HupL transcripts appear to be the most robust activity biomarker across multiple DMC strains and in mixed communities including DMC co-cultures such as KB1TM. The addition of oxygen induced cell stress that caused respiration

  5. Biomarkers' Responses to Reductive Dechlorination Rates and Oxygen Stress in Bioaugmentation Culture KB-1TM.

    Science.gov (United States)

    Heavner, Gretchen L W; Mansfeldt, Cresten B; Debs, Garrett E; Hellerstedt, Sage T; Rowe, Annette R; Richardson, Ruth E

    2018-02-08

    Using mRNA transcript levels for key functional enzymes as proxies for the organohalide respiration (OHR) rate, is a promising approach for monitoring bioremediation populations in situ at chlorinated solvent-contaminated field sites. However, to date, no correlations have been empirically derived for chlorinated solvent respiring, Dehalococcoides mccartyi (DMC) containing, bioaugmentation cultures. In the current study, genome-wide transcriptome and proteome data were first used to confirm the most highly expressed OHR-related enzymes in the bioaugmentation culture, KB-1 TM , including several reductive dehalogenases (RDases) and a Ni-Fe hydrogenase, Hup. Different KB-1™ DMC strains could be resolved at the RNA and protein level through differences in the sequence of a common RDase (DET1545-like homologs) and differences in expression of their vinyl chloride-respiring RDases. The dominant strain expresses VcrA, whereas the minor strain utilizes BvcA. We then used quantitative reverse-transcriptase PCR (qRT-PCR) as a targeted approach for quantifying transcript copies in the KB-1 TM consortium operated under a range of TCE respiration rates in continuously-fed, pseudo-steady-state reactors. These candidate biomarkers from KB-1 TM demonstrated a variety of trends in terms of transcript abundance as a function of respiration rate over the range: 7.7 × 10 -12 to 5.9 × 10 -10 microelectron equivalents per cell per hour (μeeq/cell∙h). Power law trends were observed between the respiration rate and transcript abundance for the main DMC RDase (VcrA) and the hydrogenase HupL (R² = 0.83 and 0.88, respectively), but not transcripts for 16S rRNA or three other RDases examined: TceA, BvcA or the RDase DET1545 homologs in KB1 TM . Overall, HupL transcripts appear to be the most robust activity biomarker across multiple DMC strains and in mixed communities including DMC co-cultures such as KB1 TM . The addition of oxygen induced cell stress that caused respiration rates

  6. Oxygen at Nanomolar Levels Reversibly Suppresses Process Rates and Gene Expression in Anammox and Denitrification in the Oxygen Minimum Zone off Northern Chile

    OpenAIRE

    Dalsgaard, Tage; Stewart, Frank J.; Thamdrup, Bo; De Brabandere, Loreto; Revsbech, Niels Peter; Ulloa, Osvaldo; Canfield, Don E.; DeLong, Edward

    2014-01-01

    A major percentage (20 to 40%) of global marine fixed-nitrogen loss occurs in oxygen minimum zones (OMZs). Concentrations of O[subscript 2] and the sensitivity of the anaerobic N[subscript 2]-producing processes of anammox and denitrification determine where this loss occurs. We studied experimentally how O[subscript 2] at nanomolar levels affects anammox and denitrification rates and the transcription of nitrogen cycle genes in the anoxic OMZ off Chile. Rates of anammox and denitrification w...

  7. Pleiotropic Effects of Biguanides on Mitochondrial Reactive Oxygen Species Production

    Czech Academy of Sciences Publication Activity Database

    Pecinová, Alena; Drahota, Zdeněk; Kovalčíková, Jana; Kovářová, Nikola; Pecina, Petr; Alán, Lukáš; Zima, Michal; Houštěk, Josef; Mráček, Tomáš

    2017-01-01

    Roč. 2017, č. 2017 (2017), č. článku 7038603. ISSN 1942-0900 R&D Projects: GA ČR(CZ) GA16-12726S; GA MŠk(CZ) LL1204 Institutional support: RVO:67985823 Keywords : brown adipose tissue * mitochondria * respiratory chain oxidoreductases * mitochondrial glycerophosphate dehydrogenase * superoxide production * biguanides * metformin Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 4.593, year: 2016

  8. Factors determining the oxygen consumption rate (VO2) on-kinetics in skeletal muscles.

    Science.gov (United States)

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2004-05-01

    Using a computer model of oxidative phosphorylation developed previously [Korzeniewski and Mazat (1996) Biochem. J. 319, 143-148; Korzeniewski and Zoladz (2001) Biophys. Chem. 92, 17-34], we analyse the effect of several factors on the oxygen-uptake kinetics, especially on the oxygen consumption rate (VO2) and half-transition time t(1/2), at the onset of exercise in skeletal muscles. Computer simulations demonstrate that an increase in the total creatine pool [PCr+/-Cr] (where Cr stands for creatine and PCr for phosphocreatine) and in glycolytic ATP supply lengthen the half-transition time, whereas increase in mitochondrial content, in parallel activation of ATP supply and ATP usage, in oxygen concentration, in proton leak, in resting energy demand, in resting cytosolic pH and in initial alkalization decrease this parameter. Theoretical studies show that a decrease in the activity of creatine kinase (CK) [displacement of this enzyme from equilibrium during on-transient (rest-to-work transition)] accelerates the first stage of the VO2 on-transient, but slows down the second stage of this transient. It is also demonstrated that a prior exercise terminated a few minutes before the principal exercise shortens the transition time. Finally, it is shown that at a given ATP demand, and under conditions where CK works near the thermodynamic equilibrium, the half-transition time of VO2 kinetics is determined by the amount of PCr that has to be transformed into Cr during rest-to-work transition; therefore any factor that diminishes the difference in [PCr] between rest and work at a given energy demand will accelerate the VO2 on-kinetics. Our conclusions agree with the general idea formulated originally by Easterby [(1981) Biochem. J. 199, 155-161] that changes in metabolite concentrations determine the transition times between different steady states in metabolic systems.

  9. Pedaling rate is an important determinant of human oxygen uptake during exercise on the cycle ergometer.

    Science.gov (United States)

    Formenti, Federico; Minetti, Alberto E; Borrani, Fabio

    2015-09-01

    Estimation of human oxygen uptake (V˙o2) during exercise is often used as an alternative when its direct measurement is not feasible. The American College of Sports Medicine (ACSM) suggests estimating human V˙o2 during exercise on a cycle ergometer through an equation that considers individual's body mass and external work rate, but not pedaling rate (PR). We hypothesized that including PR in the ACSM equation would improve its V˙o2 prediction accuracy. Ten healthy male participants' (age 19-48 years) were recruited and their steady-state V˙o2 was recorded on a cycle ergometer for 16 combinations of external work rates (0, 50, 100, and 150 W) and PR (50, 70, 90, and 110 revolutions per minute). V˙o2 was calculated by means of a new equation, and by the ACSM equation for comparison. Kinematic data were collected by means of an infrared 3-D motion analysis system in order to explore the mechanical determinants of V˙o2. Including PR in the ACSM equation improved the accuracy for prediction of sub-maximal V˙o2 during exercise (mean bias 1.9 vs. 3.3 mL O2 kg(-1) min(-1)) but it did not affect the accuracy for prediction of maximal V˙o2 (P > 0.05). Confirming the validity of this new equation, the results were replicated for data reported in the literature in 51 participants. We conclude that PR is an important determinant of human V˙o2 during cycling exercise, and it should be considered when predicting oxygen consumption. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

  10. Extracellular matrix production by nucleus pulposus and bone marrow stem cells in response to altered oxygen and glucose microenvironments.

    Science.gov (United States)

    Naqvi, Syeda M; Buckley, Conor T

    2015-12-01

    Bone marrow (BM) stem cells may be an ideal source of cells for intervertebral disc (IVD) regeneration. However, the harsh biochemical microenvironment of the IVD may significantly influence the biological and metabolic vitality of injected stem cells and impair their repair potential. This study investigated the viability and production of key matrix proteins by nucleus pulposus (NP) and BM stem cells cultured in the typical biochemical microenvironment of the IVD consisting of altered oxygen and glucose concentrations. Culture-expanded NP cells and BM stem cells were encapsulated in 1.5% alginate and ionically crosslinked to form cylindrical hydrogel constructs. Hydrogel constructs were maintained under different glucose concentrations (1, 5 and 25 mM) and external oxygen concentrations (5 and 20%). Cell viability was measured using the Live/Dead® assay and the production of sulphated glycosaminoglycans (sGAG), and collagen was quantified biochemically and histologically. For BM stem cells, IVD-like micro-environmental conditions (5 mM glucose and 5% oxygen) increased the accumulation of sGAG and collagen. In contrast, low glucose conditions (1 mM glucose) combined with 5% external oxygen concentration promoted cell death, inhibiting proliferation and the accumulation of sGAG and collagen. NP-encapsulated alginate constructs were relatively insensitive to oxygen concentration or glucose condition in that they accumulated similar amounts of sGAG under all conditions. Under IVD-like microenvironmental conditions, NP cells were found to have a lower glucose consumption rate compared with BM cells and may in fact be more suitable to adapt and sustain the harsh microenvironmental conditions. Considering the highly specialised microenvironment of the central NP, these results indicate that IVD-like concentrations of low glucose and low oxygen are critical and influential for the survival and biological behaviour of stem cells. Such findings may promote and accelerate

  11. A Stirred Microchamber for Oxygen Consumption Rate Measurements With Pancreatic Islets

    Science.gov (United States)

    Papas, Klearchos K.; Pisania, Anna; Wu, Haiyan; Weir, Gordon C.; Colton, Clark K.

    2010-01-01

    Improvements in pancreatic islet transplantation for treatment of diabetes are hindered by the absence of meaningful islet quality assessment methods. Oxygen consumption rate (OCR) has previously been used to assess the quality of organs and primary tissue for transplantation. In this study, we describe and characterize a stirred microchamber for measuring OCR with small quantities of islets. The device has a titanium body with a chamber volume of about 200 µL and is magnetically stirred and water jacketed for temperature control. Oxygen partial pressure (pO2) is measured by fluorescence quenching with a fiber optic probe, and OCR is determined from the linear decrease of pO2 with time. We demonstrate that measurements can be made rapidly and with high precision. Measurements with βTC3 cells and islets show that OCR is directly proportional to the number of viable cells in mixtures of live and dead cells and correlate linearly with membrane integrity measurements made with cells that have been cultured for 24 h under various stressful conditions. PMID:17497731

  12. Surface recombination of oxygen atoms in O2 plasma at increased pressure: II. Vibrational temperature and surface production of ozone

    Science.gov (United States)

    Lopaev, D. V.; Malykhin, E. M.; Zyryanov, S. M.

    2011-01-01

    Ozone production in an oxygen glow discharge in a quartz tube was studied in the pressure range of 10-50 Torr. The O3 density distribution along the tube diameter was measured by UV absorption spectroscopy, and ozone vibrational temperature TV was found comparing the calculated ab initio absorption spectra with the experimental ones. It has been shown that the O3 production mainly occurs on a tube surface whereas ozone is lost in the tube centre where in contrast the electron and oxygen atom densities are maximal. Two models were used to analyse the obtained results. The first one is a kinetic 1D model for the processes occurring near the tube walls with the participation of the main particles: O(3P), O2, O2(1Δg) and O3 molecules in different vibrational states. The agreement of O3 and O(3P) density profiles and TV calculated in the model with observed ones was reached by varying the single model parameter—ozone production probability (\\gamma_{O_{3}}) on the quartz tube surface on the assumption that O3 production occurs mainly in the surface recombination of physisorbed O(3P) and O2. The phenomenological model of the surface processes with the participation of oxygen atoms and molecules including singlet oxygen molecules was also considered to analyse \\gamma_{O_{3}} data obtained in the kinetic model. A good agreement between the experimental data and the data of both models—the kinetic 1D model and the phenomenological surface model—was obtained in the full range of the studied conditions that allowed consideration of the ozone surface production mechanism in more detail. The important role of singlet oxygen in ozone surface production was shown. The O3 surface production rate directly depends on the density of physisorbed oxygen atoms and molecules and can be high with increasing pressure and energy inputted into plasma while simultaneously keeping the surface temperature low enough. Using the special discharge cell design, such an approach opens up the

  13. Surface recombination of oxygen atoms in O2 plasma at increased pressure: II. Vibrational temperature and surface production of ozone

    International Nuclear Information System (INIS)

    Lopaev, D V; Malykhin, E M; Zyryanov, S M

    2011-01-01

    Ozone production in an oxygen glow discharge in a quartz tube was studied in the pressure range of 10-50 Torr. The O 3 density distribution along the tube diameter was measured by UV absorption spectroscopy, and ozone vibrational temperature T V was found comparing the calculated ab initio absorption spectra with the experimental ones. It has been shown that the O 3 production mainly occurs on a tube surface whereas ozone is lost in the tube centre where in contrast the electron and oxygen atom densities are maximal. Two models were used to analyse the obtained results. The first one is a kinetic 1D model for the processes occurring near the tube walls with the participation of the main particles: O( 3 P), O 2 , O 2 ( 1 Δ g ) and O 3 molecules in different vibrational states. The agreement of O 3 and O( 3 P) density profiles and T V calculated in the model with observed ones was reached by varying the single model parameter-ozone production probability (γ O 3 ) on the quartz tube surface on the assumption that O 3 production occurs mainly in the surface recombination of physisorbed O( 3 P) and O 2 . The phenomenological model of the surface processes with the participation of oxygen atoms and molecules including singlet oxygen molecules was also considered to analyse γ O 3 data obtained in the kinetic model. A good agreement between the experimental data and the data of both models-the kinetic 1D model and the phenomenological surface model-was obtained in the full range of the studied conditions that allowed consideration of the ozone surface production mechanism in more detail. The important role of singlet oxygen in ozone surface production was shown. The O 3 surface production rate directly depends on the density of physisorbed oxygen atoms and molecules and can be high with increasing pressure and energy inputted into plasma while simultaneously keeping the surface temperature low enough. Using the special discharge cell design, such an approach opens up

  14. Controls on O2 Production in Cyanobacterial Mats and Implications for Earth's Oxygenation

    Science.gov (United States)

    Dick, Gregory J.; Grim, Sharon L.; Klatt, Judith M.

    2018-05-01

    Cyanobacterial mats are widely assumed to have been globally significant hot spots of biogeochemistry and evolution during the Archean and Proterozoic, but little is known about their quantitative contributions to global primary productivity or Earth's oxygenation. Modern systems show that mat biogeochemistry is the outcome of concerted activities and intimate interactions between various microbial metabolisms. Emerging knowledge of the regulation of oxygenic and sulfide-driven anoxygenic photosynthesis by versatile cyanobacteria, and their interactions with sulfur-oxidizing bacteria and sulfate-reducing bacteria, highlights how ecological and geochemical processes can control O2 production in cyanobacterial mats in unexpected ways. This review explores such biological controls on O2 production. We argue that the intertwined effects of light availability, redox geochemistry, regulation and competition of microbial metabolisms, and biogeochemical feedbacks result in emergent properties of cyanobacterial mat communities that are all critical yet largely overlooked mechanisms to potentially explain the protracted nature of Earth's oxygenation.

  15. Comparison of Mitochondrial Reactive Oxygen Species Production of Ectothermic and Endothermic Fish Muscle

    Directory of Open Access Journals (Sweden)

    Lilian Wiens

    2017-09-01

    Full Text Available Recently we demonstrated that the capacity of isolated muscle mitochondria to produce reactive oxygen species, measured as H2O2 efflux, is temperature-sensitive in isolated muscle mitochondria of ectothermic fish and the rat, a representative endothermic mammal. However, at physiological temperatures (15° and 37°C for the fish and rat, respectively, the fraction of total mitochondrial electron flux that generated H2O2, the fractional electron leak (FEL, was far lower in the rat than in fish. Those results suggested that the elevated body temperatures associated with endothermy may lead to a compensatory decrease in mitochondrial ROS production relative to respiratory capacity. To test this hypothesis we compare slow twitch (red muscle mitochondria from the endothermic Pacific bluefin tuna (Thunnus orientalis with mitochondria from three ectothermic fishes [rainbow trout (Oncorhynchus mykiss, common carp (Cyprinus carpio, and the lake sturgeon (Acipenser fulvescens] and the rat. At a common assay temperature (25°C rates of mitochondrial respiration and H2O2 efflux were similar in tuna and the other fishes. The thermal sensitivity of fish mitochondria was similar irrespective of ectothermy or endothermy. Comparing tuna to the rat at a common temperature, respiration rates were similar, or lower depending on mitochondrial substrates. FEL was not different across fish species at a common assay temperature (25°C but was markedly higher in fishes than in rat. Overall, endothermy and warming of Pacific Bluefin tuna red muscle may increase the potential for ROS production by muscle mitochondria but the evolution of endothermy in this species is not necessarily associated with a compensatory reduction of ROS production relative to the respiratory capacity of mitochondria.

  16. Effect of oxygen flow rate on ITO thin films deposited by facing targets sputtering

    International Nuclear Information System (INIS)

    Kim, Youn J.; Jin, Su B.; Kim, Sung I.; Choi, Yoon S.; Choi, In S.; Han, Jeon G.

    2010-01-01

    Tin-doped indium oxide (ITO) thin films were deposited on glass substrates at various oxygen flow rates using a planar magnetron sputtering system with facing targets. In this system, the strong internal magnets inside the target holders confine the plasma between the targets. High resolution transmission electron microscopy revealed a combination of amorphous and crystalline phases on the glass substrate. X-ray photoelectron spectroscopy suggested that the decrease in carrier concentration and increase in mobility were caused by a decrease in the concentration of Sn 4+ states. The electrical and optical properties of the ITO films were examined by Hall measurements and UV-visible spectroscopy, which showed a film resistivity and transmittance of 4.26 x l0 -4 Ω cm, and > 80% in the visible region, respectively.

  17. Design a Wearable Device for Blood Oxygen Concentration and Temporal Heart Beat Rate

    Science.gov (United States)

    Myint, Cho Zin; Barsoum, Nader; Ing, Wong Kiing

    2010-06-01

    The wireless network technology is increasingly important in healthcare as a result of the aging population and the tendency to acquire chronic disease such as heart attack, high blood pressure amongst the elderly. A wireless sensor network system that has the capability to monitor physiological sign such as SpO2 (Saturation of Arterial Oxygen) and heart beat rate in real-time from the human's body is highlighted in this study. This research is to design a prototype sensor network hardware, which consists of microcontroller PIC18F series and transceiver unit. The sensor is corporate into a wearable body sensor network which is small in size and easy to use. The sensor allows a non invasive, real time method to provide information regarding the health of the body. This enables a more efficient and economical means for managing the health care of the population.

  18. Increasing arterial oxygen partial pressure during cardiopulmonary resuscitation is associated with improved rates of hospital admission.

    Science.gov (United States)

    Spindelboeck, Walter; Schindler, Otmar; Moser, Adrian; Hausler, Florian; Wallner, Simon; Strasser, Christa; Haas, Josef; Gemes, Geza; Prause, Gerhard

    2013-06-01

    As recent clinical data suggest a harmful effect of arterial hyperoxia on patients after resuscitation from cardiac arrest (CA), we aimed to investigate this association during cardiopulmonary resuscitation (CPR), the earliest and one of the most crucial phases of recirculation. We analysed 1015 patients who from 2003 to 2010 underwent out-of-hospital CPR administered by emergency medical services serving 300,000 inhabitants. Inclusion criteria for further analysis were nontraumatic background of CA and patients >18 years of age. One hundred and forty-five arterial blood gas analyses including oxygen partial pressure (paO2) measurement were obtained during CPR. We observed a highly significant increase in hospital admission rates associated with increases in paO2 in steps of 100 mmHg (13.3 kPa). Subsequently, data were clustered according to previously described cutoffs (≤ 60 mmHg [8 kPa

  19. Heart rate during basketball game play and volleyball drills accurately predicts oxygen uptake and energy expenditure.

    Science.gov (United States)

    Scribbans, T D; Berg, K; Narazaki, K; Janssen, I; Gurd, B J

    2015-09-01

    There is currently little information regarding the ability of metabolic prediction equations to accurately predict oxygen uptake and exercise intensity from heart rate (HR) during intermittent sport. The purpose of the present study was to develop and, cross-validate equations appropriate for accurately predicting oxygen cost (VO2) and energy expenditure from HR during intermittent sport participation. Eleven healthy adult males (19.9±1.1yrs) were recruited to establish the relationship between %VO2peak and %HRmax during low-intensity steady state endurance (END), moderate-intensity interval (MOD) and high intensity-interval exercise (HI), as performed on a cycle ergometer. Three equations (END, MOD, and HI) for predicting %VO2peak based on %HRmax were developed. HR and VO2 were directly measured during basketball games (6 male, 20.8±1.0 yrs; 6 female, 20.0±1.3yrs) and volleyball drills (12 female; 20.8±1.0yrs). Comparisons were made between measured and predicted VO2 and energy expenditure using the 3 equations developed and 2 previously published equations. The END and MOD equations accurately predicted VO2 and energy expenditure, while the HI equation underestimated, and the previously published equations systematically overestimated VO2 and energy expenditure. Intermittent sport VO2 and energy expenditure can be accurately predicted from heart rate data using either the END (%VO2peak=%HRmax x 1.008-17.17) or MOD (%VO2peak=%HRmax x 1.2-32) equations. These 2 simple equations provide an accessible and cost-effective method for accurate estimation of exercise intensity and energy expenditure during intermittent sport.

  20. The oxygen consumption rates of different life stages of the endoparasitic nematode

    Directory of Open Access Journals (Sweden)

    Willie van Aardt

    2010-01-01

    Full Text Available The oxygen consumption rates of different life stages of the endoparasitic nematode, Pratylenchus zeae (Nematoda: Tylenchida during non- and post-anhydrobiosisPratylenchus zeae, widely distributed in tropical and subtropical regions, is an endoparasite in roots of maize and other crop plants. The nematode is attracted to plant roots by CO2 and root exudates and feeds primarily on cells of the root cortex, making channels and openings where the eggs are deposited, with the result that secondary infection occurs due to bacteria and fungi. Nothing is known about the respiration physiology of this nematode and how it manages to survive during dry seasons. To measure the oxygen consumption rate (VO2 of individual P. zeae (less than half a millimeter long, a special measuring technique namely Cartesian diver micro-respirometry was applied. The Cartesian divers were machined from Perspex, and proved to be more accurate to measure VO2 compared with heavier glass divers used in similar experiments on free living nematodes. An accuracy of better than one nanoliter of oxygen consumed per hour was achieved with a single P. zeae inside the diver. Cartesian diver micro-respirometry measurements are based in principle on the manometric changes that occur in a fl otation tube in a manometer set-up when oxygen is consumed by P. zeae and CO2 from the animal is chemically absorbed. VO2 was measured for eggs (length: < 0.05 mm, larvae (length: 0.36 mm and adults (length: 0.47 mm before induction to anhydrobiosis. P. zeae from infected maize roots were extracted and exposed aseptically to in vitro maize root cultures in a grow cabinet at 50 % to 60% relative humidity at 28 ºC using eggs, larvae and adults. VO2 was also measured for post-anhydrobiotic eggs, larvae and adults by taking 50 individuals, eggs and larvae from the culture and placing them in Petri-dishes with 1% agar/water to dry out for 11 days at 28 ºC and 50% relative humidity. The VO2 was measured

  1. Changes of heart rate variability and prefrontal oxygenation during Tai Chi practice versus arm ergometer cycling.

    Science.gov (United States)

    Lu, Xi; Hui-Chan, Christina Wan-Ying; Tsang, William Wai-Nam

    2016-11-01

    [Purpose] Exercise has been shown to improve cardiovascular fitness and cognitive function. Whether the inclusion of mind over exercise would increase parasympathetic control of the heart and brain activities more than general exercise at a similar intensity is not known. The aim of this study was to compare the effects of Tai Chi (mind-body exercise) versus arm ergometer cycling (body-focused exercise) on the heart rate variability and prefrontal oxygenation level. [Subjects and Methods] A Tai Chi master was invited to perform Tai Chi and arm ergometer cycling with similar exercise intensity on two separate days. Heart rate variability and prefrontal oxyhemoglobin levels were measured continuously by a RR recorder and near-infrared spectroscopy, respectively. [Results] During Tai Chi exercise, spectral analysis of heart rate variability demonstrated a higher high-frequency power as well as a lower low-frequency/high-frequency ratio than during ergometer cycling, suggesting increased parasympathetic and decreased sympathetic control of the heart. Also, prefrontal oxyhemoglobin and total hemoglobin levels were higher than those during arm ergometer exercise. [Conclusion] These findings suggest that increased parasympathetic control of the heart and prefrontal activities may be associated with Tai Chi practice. Having a "mind" component in Tai Chi could be more beneficial for older adults' cardiac health and cognitive function than body-focused ergometer cycling.

  2. Recombination rates of hydrogen and oxygen over pure and impure plutonium oxides

    International Nuclear Information System (INIS)

    Morales, L.

    1999-01-01

    Long-term, safe storage of excess plutonium-bearing materials is required until stabilization and disposal methods are implemented or defined. The US Department of Energy (DOE) has established a plan to address the stabilization, packing, and storage of plutonium-bearing materials from around the complex. The DOE's standard method, DOE-STD-3013-96 and its proposed revision, for stabilizing pure and impure actinide materials is by calcination in air followed by sealing the material in welded stainless steel containers. The 3013 standard contains and equation that predicts the total pressure buildup in the can over the anticipated storage time of 50 yr. This equation was meant to model a worst-case scenario to ensure that pressures would not exceed the strength of the container at the end of 50 yr. As a result, concerns about pressure generation in the storage cans, both absolute values and rates, have been raised with regard to rupture and dispersal of nuclear materials. Similar issues have been raised about the transportation of these materials around the complex. The purpose of this work is to provide a stronger technical basis for the 3013 standard by measuring the recombination rates of hydrogen/oxygen mixtures in contact with pure and impure plutonium oxides. The goal of these experiments was to determine whether the rate of recombination is faster than the rate of water radiolysis under controlled conditions. This was accomplished by using a calibrated pressure-volume-temperature apparatus to measure the recombination rates in a fixed volume as the gas mixture was brought into contact with oxide powders whose temperatures ranged from 50 to 300 C. These conditions were selected in order to bracket the temperature conditions expected in a typical storage can. In addition, a 2% H 2 /air mixture encompasses scenarios in which the cans are sealed in air, and over time various amounts of hydrogen are formed

  3. Parabanic acid is the singlet oxygen specific oxidation product of uric acid.

    Science.gov (United States)

    Iida, Sayaka; Ohkubo, Yuki; Yamamoto, Yorihiro; Fujisawa, Akio

    2017-11-01

    Uric acid quenches singlet oxygen physically or reacts with it, but the oxidation product has not been previously characterized. The present study determined that the product is parabanic acid, which was confirmed by LC/TOFMS analysis. Parabanic acid was stable at acidic pH (acid at neutral or alkaline pH. The total yields of parabanic acid and oxaluric acid based on consumed uric acid were ~100% in clean singlet oxygen production systems such as UVA irradiation of Rose Bengal and thermal decomposition of 3-(1,4-dihydro-1,4-epidioxy-4-methyl-1-naphthyl)propionic acid. However, the ratio of the amount of uric acid consumed to the total amount of singlet oxygen generated was less than 1/180, indicating that most of the singlet oxygen was physically quenched. The total yields of parabanic acid and oxaluric acid were high in the uric acid oxidation systems with hydrogen peroxide plus hypochlorite or peroxynitrite. They became less than a few percent in peroxyl radical-, hypochlorite- or peroxynitrite-induced oxidation of uric acid. These results suggest that parabanic acid could be an in vivo probe of singlet oxygen formation because of the wide distribution of uric acid in human tissues and extracellular spaces. In fact, sunlight exposure significantly increased human skin levels of parabanic acid.

  4. Assessment of heart rate, acidosis, consciousness, oxygenation, and respiratory rate to predict noninvasive ventilation failure in hypoxemic patients.

    Science.gov (United States)

    Duan, Jun; Han, Xiaoli; Bai, Linfu; Zhou, Lintong; Huang, Shicong

    2017-02-01

    To develop and validate a scale using variables easily obtained at the bedside for prediction of failure of noninvasive ventilation (NIV) in hypoxemic patients. The test cohort comprised 449 patients with hypoxemia who were receiving NIV. This cohort was used to develop a scale that considers heart rate, acidosis, consciousness, oxygenation, and respiratory rate (referred to as the HACOR scale) to predict NIV failure, defined as need for intubation after NIV intervention. The highest possible score was 25 points. To validate the scale, a separate group of 358 hypoxemic patients were enrolled in the validation cohort. The failure rate of NIV was 47.8 and 39.4% in the test and validation cohorts, respectively. In the test cohort, patients with NIV failure had higher HACOR scores at initiation and after 1, 12, 24, and 48 h of NIV than those with successful NIV. At 1 h of NIV the area under the receiver operating characteristic curve was 0.88, showing good predictive power for NIV failure. Using 5 points as the cutoff value, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for NIV failure were 72.6, 90.2, 87.2, 78.1, and 81.8%, respectively. These results were confirmed in the validation cohort. Moreover, the diagnostic accuracy for NIV failure exceeded 80% in subgroups classified by diagnosis, age, or disease severity and also at 1, 12, 24, and 48 h of NIV. Among patients with NIV failure with a HACOR score of >5 at 1 h of NIV, hospital mortality was lower in those who received intubation at ≤12 h of NIV than in those intubated later [58/88 (66%) vs. 138/175 (79%); p = 0.03). The HACOR scale variables are easily obtained at the bedside. The scale appears to be an effective way of predicting NIV failure in hypoxemic patients. Early intubation in high-risk patients may reduce hospital mortality.

  5. Regulation of primary productivity rate in the equatorial Pacific

    International Nuclear Information System (INIS)

    Barber, R.T.; Chavez, F.P.

    1991-01-01

    Analysis of the Chl-specific rate of primary productivity (P B ) as a function of subsurface nutrient concentration at >300 equatorial stations provides an answer to the question: What processes regulate primary productivity rate in the high-nutrient, low-chlorophyll waters of the equatorial Pacific? In the western Pacific where there is a gradient in 60-m [NO 3 ] from 0 to ∼12 μM, the productivity rate is a linear function of nutrient concentration; in the eastern Pacific where the gradient is from 12 to 28 μM, the productivity rate is independent of nutrient concentration and limited to ∼36 mg C(mg Chl) -1 d -1 , or a mean euphotic zone C-specific growth rate (μ) of 0.47 d -1 . However, rates downstream of the Galapagos Islands are not limited; they are 46.4 mg C(mg Chl) -1 d -1 and μ = 0.57 d -1 , very close to the predicted nutrient-regulated rates in the absence of other limitation. This pattern of rate regulation can be accounted for by a combination of eolian Fe, subsurface nutrients, and sedimentary Fe derived from the Galapagos platform. In the low-nutrient western Pacific the eolian supply of Fe is adequate to allow productivity rate to be set by subsurface nutrient concentration. In the nutrient-rich easter equatorial region eolian Fe is inadequate to support productivity rates proportional to the higher nutrient concentrations, so in this region eolian Fe is rate limiting. Around the Galapagos Islands productivity rates reach levels consistent with nutrient concentrations; sedimentary Fe from the Galapagos platform seems adequate to support increased nutrient-regulated productivity rates in this region

  6. Oxygen consumption and heart rate responses to isolated ballet exercise sets.

    Science.gov (United States)

    Rodrigues-Krause, Josianne; Dos Santos Cunha, Giovani; Alberton, Cristine Lima; Follmer, Bruno; Krause, Mauricio; Reischak-Oliveira, Alvaro

    2014-01-01

    Ballet stage performances are associated with higher cardiorespiratory demand than rehearsals and classes. Hence, new interest is emerging to create periodized training that enhances dancers' fitness while minimizing delayed exercise-induced fatigue and possible injuries. Finding out in what zones of intensity dancers work during different ballet movements may support the use of supplemental training adjusted to the needs of the individual dancer. Therefore, the main purpose of this study was to describe dancers' oxygen consumption (VO2) and heart rate (HR) responses during the performance of nine isolated ballet exercise sets, as correlated with their first and second ventilatory thresholds (VT1 and VT2). Twelve female ballet dancers volunteered for the study. Their maximum oxygen consumption (VO2max), VT1, and VT2 were determined by use of an incremental treadmill test. Nine sets of ballet movements were assessed: pliés, tendus, jetés, rond de jambes, fondus, grand adage (adage), grand battements, temps levés, and sautés. The sets were randomly executed and separated by 5 minute rest periods. ANOVA for repeated measurements followed by the Bonferroni Post-hoc test were applied (p ballet sets. This stratification followed closely, but not exactly, the variation in HR. For example, rond de jambes (156.8 ± 19 b·min(-1)) did not show any significant difference from all the other ballet sets, nor VT1 or VT2. It is concluded that the workloads of isolated ballet sets, based on VO2 responses, vary between low and moderate aerobic intensity in relation to dancers' VT1 and VT2. However, ballet set workloads may be higher when based on HR responses, due to the intermittent and isometric components of dance.

  7. Dose-rate and oxygen effects in models of lipid membranes: linoleic acid

    Energy Technology Data Exchange (ETDEWEB)

    Raleigh, J A; Kremers, W; Gaboury, B [Atomic Energy of Canada Ltd., Pinawa, Manitoba. Whiteshell Nuclear Research Establishment

    1977-03-01

    Cellular membranes have been suggested as possible loci for the development of the oxygen effect in radiobiology. Unsaturated lipids from membranes are subject to very efficient radiation-induced peroxidation, and the deleterious effects generally associated with lipid autoxidation could be initiated by ionizing radiation. Oxidative damage in lipids was characterized not only by high yields but also by a profound dose-rate effect. At dose-rates of x irradiation below 100 rad/min, a very sharp rise occurred in oxidative damage. This damage has been quantified spectrophotometrically in terms of diene conjugation (O.D. 234 mm) and chromatographically in terms of specific 9- and 13-hydroperoxide formation in linoleic acid micelles. Radical scavenging experiments indicated that hydroxyl radical attack initiated the oxidative damage. Dimethyl sulphoxide is exceptional in that it did not protect, but sensitized, linoleic acid to radiation-induced peroxidation. The yields of hydroperoxides were substantial (G = 10 to 40) and could be related to biological changes known to be effected by autoxidizing lipids.

  8. Productivity Demand Shocks And Asia-Pacific Real Exchange Rates

    OpenAIRE

    Ordean Olson

    2011-01-01

    The evidence for a productivity-based explanation for real exchange rate behavior of East Asian currencies is examined using sectoral output and employment data, relative prices and relative productivities for China, Indonesia, Japan, Korea, Malaysia, Philippines, Singapore, Taiwan, and Thailand. Time series regressions of the real exchange rate on relative productivity ratios indicate significant relationships for the Philippines, Hong Kong, Thailand, Singapore, Taiwan and Korea. Only when a...

  9. Role of N2 molecules in pulse discharge production of I atoms for a pulsed chemical oxygen-iodine laser

    International Nuclear Information System (INIS)

    Kochetov, I V; Napartovich, A P; Vagin, N P; Yuryshev, N N

    2011-01-01

    A pulsed electric discharge is the most effective means to turn chemical oxygen-iodine laser (COIL) operation into the pulse mode by fast production of iodine atoms. Experimental studies and numerical simulations are performed on a pulsed COIL initiated by an electric discharge in a mixture CF 3 I : N 2 : O 2 ( 3 X) : O 2 (a 1 Δ g ) flowing out of a chemical singlet oxygen generator. A transverse pulsed discharge is realized at various iodide pressures. The model comprises a system of kinetic equations for neutral and charged species, the electric circuit equation, the gas thermal balance equation and the photon balance equation. Reaction rate coefficients for processes involving electrons are repeatedly re-calculated by the electron Boltzmann equation solver when the plasma parameters are changed. The processes accounted for in the Boltzmann equation include direct and stepwise excitation and ionization of atoms and molecules, dissociation of molecules, electron attachment processes, electron-ion recombination, electron-electron collisions and second-kind collisions. The last processes are particularly important because of a high singlet oxygen concentration in gas flow from the singlet oxygen chemical generator. A conclusion is drawn about satisfactory agreement between the theory and the experiment.

  10. Application of dimensional analysis to ozone production by pulsed streamer discharge in oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Buntat, Z; Harry, J E; Smith, I R [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)

    2003-07-07

    This paper describes the use of dimensional analysis in investigating the effects of the electrical and the discharge configuration parameters on ozone production in oxygen, by means of a pulsed streamer discharge. Ozone destruction factors are taken into account in the model, and predicted results are shown to be in good agreement with experimental findings.

  11. Application of dimensional analysis to ozone production by pulsed streamer discharge in oxygen

    CERN Document Server

    Buntat, Z; Smith, I R

    2003-01-01

    This paper describes the use of dimensional analysis in investigating the effects of the electrical and the discharge configuration parameters on ozone production in oxygen, by means of a pulsed streamer discharge. Ozone destruction factors are taken into account in the model, and predicted results are shown to be in good agreement with experimental findings.

  12. Application of dimensional analysis to ozone production by pulsed streamer discharge in oxygen

    International Nuclear Information System (INIS)

    Buntat, Z; Harry, J E; Smith, I R

    2003-01-01

    This paper describes the use of dimensional analysis in investigating the effects of the electrical and the discharge configuration parameters on ozone production in oxygen, by means of a pulsed streamer discharge. Ozone destruction factors are taken into account in the model, and predicted results are shown to be in good agreement with experimental findings

  13. Application of dimensional analysis to ozone production by pulsed streamer discharge in oxygen

    Science.gov (United States)

    Buntat, Z.; Harry, J. E.; Smith, I. R.

    2003-07-01

    This paper describes the use of dimensional analysis in investigating the effects of the electrical and the discharge configuration parameters on ozone production in oxygen, by means of a pulsed streamer discharge. Ozone destruction factors are taken into account in the model, and predicted results are shown to be in good agreement with experimental findings.

  14. The economic production lot size model extended to include more than one production rate

    DEFF Research Database (Denmark)

    Larsen, Christian

    2001-01-01

    btween the demand rate and the production rate which minimizes unit production costs, and should be used in an increasing order. Then, given the production rates, we derive closed-form expressions for all optimal runtimes as well as the minimum average cost. This analysis reveals that it is the size...... of the setup cost that determines the need for being able to use several production rates. Finally, we show how to derive a near-optimal solution of the general problem....

  15. Is the surface oxygen exchange rate linked to bulk ion diffusivity in mixed conducting Ruddlesden-Popper phases?

    Science.gov (United States)

    Tomkiewicz, Alex C; Tamimi, Mazin A; Huq, Ashfia; McIntosh, Steven

    2015-01-01

    The possible link between oxygen surface exchange rate and bulk oxygen anion diffusivity in mixed ionic and electronic conducting oxides is a topic of great interest and debate. While a large body of experimental evidence and theoretical analyses support a link, observed differences between bulk and surface composition of these materials are hard to reconcile with this observation. This is further compounded by potential problems with simultaneous measurement of both parameters. Here we utilize separate techniques, in situ neutron diffraction and pulsed isotopic surface exchange, to examine bulk ion mobility and surface oxygen exchange rates of three Ruddlesden-Popper phases, general form A(n-1)A(2)'B(n)O(3n+1), A(n-1)A(2)'B(n)X(3n+1); LaSrCo(0.5)Fe(0.5)O(4-δ) (n = 1), La(0.3)Sr(2.7)CoFeO(7-δ) (n = 2) and LaSr3Co(1.5)Fe(1.5)O(10-δ) (n = 3). These measurements are complemented by surface composition determination via high sensitivity-low energy ion scattering. We observe a correlation between bulk ion mobility and surface exchange rate between materials. The surface exchange rates vary by more than one order of magnitude with high anion mobility in the bulk of an oxygen vacancy-rich n = 2 Ruddlesden-Popper material correlating with rapid oxygen exchange. This is in contrast with the similar surface exchange rates which we may expect due to similar surface compositions across all three samples. We conclude that experimental limitations lead to inherent convolution of surface and bulk rates, and that surface exchange steps are not likely to be rate limiting in oxygen incorporation.

  16. Assessment of vehicle trip production rates in Ilorin (Nigeria) | Jimoh ...

    African Journals Online (AJOL)

    Occupation, age, gender, income lev-el, vehicle ownership, trip length and fare structure affected the total trip generation, with an average production rate of 3.5, in the range of 2.79 - 4.29. The lower rate was characteristic of school children (5 - 15 years), while the highest rate was attributed to affluent and elderly persons ...

  17. The study of excited oxygen molecule gas species production and quenching on thermal protection system materials

    Science.gov (United States)

    Nordine, Paul C.; Fujimoto, Gordon T.; Greene, Frank T.

    1987-01-01

    The detection of excited oxygen and ozone molecules formed by surface catalyzed oxygen atom recombination and reaction was investigated by laser induced fluorescence (LIF), molecular beam mass spectrometric (MBMS), and field ionization (FI) techniques. The experiment used partially dissociated oxygen flows from a microwave discharge at pressures in the range from 60 to 400 Pa or from an inductively coupled RF discharge at atmospheric pressure. The catalyst materials investigated were nickel and the reaction cured glass coating used for Space Shuttle reusable surface insulation tiles. Nonradiative loss processes for the laser excited states makes LIF detection of O2 difficult such that formation of excited oxygen molecules could not be detected in the flow from the microwave discharge or in the gaseous products of atom loss on nickel. MBMS experiments showed that ozone was a product of heterogeneous O atom loss on nickel and tile surfaces at low temperatures and that ozone is lost on these materials at elevated temperatures. FI was separately investigated as a method by which excited oxygen molecules may be conveniently detected. Partial O2 dissociation decreases the current produced by FI of the gas.

  18. Molecular Ions in Ion Upflows and their Effects on Hot Atomic Oxygen Production

    Science.gov (United States)

    Foss, V.; Yau, A. W.; Shizgal, B.

    2017-12-01

    We present new direct ion composition observations of molecular ions in auroral ion upflows from the CASSIOPE Enhanced Polar Outflow Probe (e-POP). These observed molecular ions are N2+, NO+, and possibly O2+, and are found to occur at all e-POP altitudes starting at about 400 km, during auroral substorms and the different phases of magnetic storms, sometimes with upflow velocities exceeding a few hundred meters per second and abundances of 5-10%. The dissociative recombination of both O2+ and NO+ was previously proposed as an important source of hot oxygen atoms in the topside thermosphere [Hickey et al., 1995]. We investigate the possible effect of the observed molecular ions on the production of hot oxygen atoms in the storm and substorm-time auroral thermosphere. We present numerical solutions of the Boltzmann equation for the steady-state oxygen energy distribution function, taking into account both the production of the hot atoms and their subsequent collisional relaxation. Our result suggests the formation of a hot oxygen population with a characteristic temperature on the order of 0.3 eV and constituting 1-5% of the oxygen density near the exobase. We discuss the implication of this result in the context of magnetosphere-ionosphere-thermosphere coupling.

  19. Oxygen Concentration Inside a Functioning Photosynthetic Cell

    OpenAIRE

    Kihara, Shigeharu; Hartzler, Daniel A.; Savikhin, Sergei

    2014-01-01

    The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic...

  20. Acute effect of ivabradine on heart rate and myocardial oxygen consumption in dogs with asymptomatic mitral valve degeneration.

    Science.gov (United States)

    Pirintr, Prapawadee; Limprasutr, Vudhiporn; Saengklub, Nakkawee; Pavinadol, Parnpradub; Yapao, Napat; Limvanicharat, Natthakarn; Kuecharoen, Hathaisiri; Kijtawornrat, Anusak

    2018-05-14

    Degenerative mitral valve disease (DMVD) is a common cardiac disease in geriatric dogs characterized by the degeneration of the mitral valve, leading to decreased cardiac output and activation of the sympathetic and renin-angiotensin-aldosterone system. This disease results in an increased resting heart rate (HR) and myocardial oxygen consumption (MVO 2 ). A recent publication demonstrated that dogs with asymptomatic DMVD had a significantly higher HR and systemic blood pressure (BP) than age-matched control dogs. This higher HR will eventually contribute to increased MVO 2 . This study aimed to determine the effects of a single oral dose of ivabradine on the HR, MVO 2 as assessed by the rate-pressure product, and BP in dogs with asymptomatic DMVD. Seven beagles with naturally occurring DMVD were instrumented by the Holter recorder and an oscillometric device to measure electrocardiogram and BP for 24 and 12 h, respectively. Each dog was randomly subjected to receive either placebo or ivabradine (0.5, 1.0 and 2.0 mg/kg). The results revealed that oral administration of ivabradine significantly decreased the HR and rate-pressure product in a dose-dependent manner without adverse effects. The highest dose of 2.0 mg/kg significantly reduced systolic and mean BP. Therefore, the findings imply that a single oral ivabradine administration at a dose of 1.0 mg/kg is suitable for dogs with asymptomatic DMVD to reduce the HR and MVO 2 without marked effects on BP. This may potentially make ivabradine promising for management of an elevated HR in DMVD dogs.

  1. Temperature dependence of electrocatalytic and photocatalytic oxygen evolution reaction rates using NiFe oxide

    KAUST Repository

    Nurlaela, Ela

    2016-01-25

    The present work compares oxygen evolution reaction (OER) in electrocatalysis and photocatalysis in aqueous solutions using nanostructured NiFeOx as catalysts. The impacts of pH and reaction temperature on the electrocatalytic and photocatalytic OER kinetics were investigated. For electrocatalysis, a NiFeOx catalyst was hydrothermally decorated on Ni foam. In 1 M KOH solution, the NiFeOx electrocatalyst achieved 10 mA cm-2 at an overpotential of 260 mV. The same catalyst was decorated on the surface of Ta3N5 photocatalyst powder. The reaction was conducted in the presence of 0.1 M Na2S2O8 as a strong electron scavenger, thus likely leading to the OER being kinetically relevant. When compared with the bare Ta3N5, NiFeOx/Ta3N5 demonstrated a 5-fold improvement in photocatalytic activity in the OER under visible light irradiation, achieving a quantum efficiency of 24 % at 480 nm. Under the conditions investigated, a strong correlation between the electrocatalytic and photocatalytic performances was identified: an improvement in electrocatalysis corresponded with an improvement in photocatalysis without altering the identity of the materials. The rate change at different pH was likely associated with electrocatalytic kinetics that accordingly influenced the photocatalytic rates. The sensitivity of the reaction rates with respective to the reaction temperature resulted in an apparent activation energy of 25 kJ mol-1 in electrocatalysis, whereas that in photocatalysis was 16 kJ mol-1. The origin of the difference in these activation energy values is likely attributed to the possible effects of temperature on the individual thermodynamic and kinetic parameters of the reaction process. The work described herein demonstrates a method of “transferring the knowledge of electrocatalysis to photocatalysis” as a strong tool to rationally and quantitatively understand the complex reaction schemes involved in photocatalytic reactions.

  2. Oxidation of D-glucose and D-fructose with oxygen in aqueous, alkaline solutions. III. Kinetic approach to the product distribution

    NARCIS (Netherlands)

    de Wilt, H.G.J.; Kuster, Ben

    1972-01-01

    Based on a previously reported, integral reaction-scheme for the homogeneous oxidation of -glucose and -fructose with oxygen in aqueous, alkaline solutions, a kinetic model covering the product distribution has been developed. The model consists of a repeated set of reactions with constant rate

  3. Evaluation of Primary Production in the Lower Amazon River Based on a Dissolved Oxygen Stable Isotopic Mass Balance

    Energy Technology Data Exchange (ETDEWEB)

    Gagne-Maynard, William C.; Ward, Nicholas D.; Keil, Richard G.; Sawakuchi, Henrique O.; Da Cunha, Alan C.; Neu, Vania; Brito, Daimio C.; Da Silva Less, Diani F.; Diniz, Joel E. M.; De Matos Valerio, Aline; Kampel, Milton; Krusche, Alex V.; Richey, Jeffrey E.

    2017-02-07

    The Amazon River outgasses nearly an equivalent amount of CO2 as the rainforest sequesters on an annual basis due to microbial decomposition of terrigenous and aquatic organic matter. Most research performed in the Amazon has been focused on unraveling the mechanisms driving CO2 production since the recognition of a persistent state of CO2 supersaturation. However, although the river system is clearly net heterotrophic, the interplay between primary production and respiration is an essential aspect to understanding the overall metabolism of the ecosystem and potential transfer of energy up trophic levels. For example, an efficient ecosystem is capable of both decomposing high amounts of organic matter at lower trophic levels, driving CO2 emissions, and accumulating energy/biomass in higher trophic levels, stimulating fisheries production. Early studies found minimal evidence for primary production in the Amazon River mainstem and it has since been assumed that photosynthesis is strongly limited by low light penetration attributed to the high sediment load. Here, we test this assumption by measuring the stable isotopic composition of O218O-O2) and O2 saturation levels in the lower Amazon River from Óbidos to the river mouth and its major tributaries, the Xingu and Tapajós rivers, during high and low water periods. An oxygen mass balance model was developed to estimate the input of photosynthetic oxygen in the discrete reach from Óbidos to Almeirim, midway to the river mouth. Based on the oxygen mass balance we estimate that primary production occurred at a rate of 0.39 ± 0.24 g O m3 d-1 at high water and 1.02 ± 0.55 g O m3 d-1 at low water. This translates to 41 ± 24% of the rate of O2 drawdown via respiration during high water and 67 ± 33% during low water. These primary production rates are 2-7 times higher than

  4. Oxygen consumption rate and Na+/K+-ATPase activity in early developmental stages of the sea urchin Paracentrotus lividus Lam.

    Science.gov (United States)

    Tomšić, Sanja; Stanković, Suzana; Lucu, Čedomil

    2011-09-01

    Changes in oxygen consumption rate and Na+/K+-ATPase activity during early development were studied in the sea urchin Paracentrotus lividus Lam. The oxygen consumption rate increased from 0.12 μmol O2 mg protein-1 h-1 in unfertilized eggs to 0.38 μmol O2 mg protein-1 h-1 25 min after fertilization. Specific activity of the Na+/K+-ATPase was significantly stimulated after fertilization, ranging up to 1.07 μmol Pi h-1 mg protein-1 in the late blastula stage and slightly lower values in the early and late pluteus stages.

  5. The economic production lot size model extended to include more than one production rate

    DEFF Research Database (Denmark)

    Larsen, Christian

    2005-01-01

    production rates should be chosen in the interval between the demand rate and the production rate which minimizes unit production costs, and should be used in an increasing order. Then, given the production rates, we derive closed-form expressions for all optimal runtimes as well as the minimum average cost....... This analysis reveals that it is the size of the setup cost that determines the need for being able to use several production rates. We also show how to derive a near-optimal solution of the general problem....

  6. Do individuals with intellectual disability have a lower peak heart rate and maximal oxygen uptake?

    Science.gov (United States)

    Hilgenkamp, Thessa Irena Maria; Baynard, Tracy

    2017-12-12

    Individuals with intellectual disability (ID) have very low physical activity and low peak oxygen uptake (VO 2peak ), potentially explained by physiologically lower peak heart rates (HR peak ). The present authors performed a retrospective analysis of a large data set of individuals with intellectual disability (n = 100), with Down syndrome (DS) (n = 48) and without intellectual disability (n = 224) using multiple linear regression analyses, to determine if individuals with intellectual disability exhibit lower HR peak and VO 2peak than individuals without intellectual disability, controlling for age, sex and body mass index (BMI). Individuals with intellectual disability on average have significantly lower HR peak and VO 2peak than individuals without intellectual disability, even when controlling VO 2peak for the lower HR peak . This study suggests potential physiological differences in individuals with intellectual disability and warrants further investigation to determine their relevance to physical activity promotion and exercise testing in individuals with intellectual disability. © 2017 John Wiley & Sons Ltd.

  7. Population densities and rate coefficients for electron impact excitation in singly ionized oxygen

    International Nuclear Information System (INIS)

    Awakowicz, P.; Behringer, K.

    1995-01-01

    In non-LTE arc plasmas, O II excited state number densities were measured relative to the O II ground and metastable states. The results were compared with collisional-radiative code calculations on the basis of the JET ADAS programs. Stationary He plasmas with small oxygen admixtures, generated in a 5 mm diameter cascade arc chamber (pressures 13-70 hPa, arc current 150 A), were investigated spectroscopically in the visible and the VUV spectral range. The continuum of a 2 mm diameter pure He arc (atmospheric pressure, current 100 A) served for calibration of the VUV system response. Plasma diagnostics on the basis of Hβ Stark broadening yielded electron densities between 2.4 x 10 14 and 2.0 x 10 15 cm -3 for the low-pressure O II mixture plasmas. The agreement of measured and calculated excited state populations is generally very satisfactory, thus confirming the rate coefficients in the code. This is of particular interest in this intermediate region between corona balance and LTE, where many atomic data are required in the simulation. Clear indications were found for the diffusion of metastables lowering their number densities significantly below their statistical values. (author)

  8. Physics and engineering of singlet delta oxygen production in low-temperature plasma

    International Nuclear Information System (INIS)

    Ionin, A A; Kochetov, I V; Napartovich, A P; Yuryshev, N N

    2007-01-01

    An overview is presented of experimental and theoretical research in the field of physics and engineering of singlet delta oxygen (SDO) production in low-temperature plasma of various electric discharges. Attention is paid mainly to the SDO production with SDO yield adequate for the development of an electric discharge oxygen-iodine laser (DOIL). The review comprises a historical sketch describing the main experimental results on SDO physics in low-temperature plasma obtained since the first detection of SDO in electric discharge in the 1950s and the first attempt to launch a DOIL in the 1970s up to the mid-1980s when several research groups started their activity aimed at DOIL development, stimulated by success in the development of a chemical oxygen-iodine laser (COIL). A detailed analysis of theoretical and experimental research on SDO production in electric discharge from the mid-1980s to the present, when the first DOIL has been launched, is given. Different kinetic models of oxygen low-temperature plasma are compared with the model developed by the authors. The latter comprises electron kinetics based on the accompanying solution of the electron Boltzmann equation, plasma chemistry including reactions of excited molecules and numerous ion-molecular reactions, thermal energy balance and electric circuit equation. The experimental part of the overview is focused on the experimental methods of SDO detection including experiments on the measurements of the Einstein coefficient for SDO transition a 1 Δ g - X 3 Σ g - and experimental procedures of SDO production in self-sustained and non-self-sustained discharges and analysis of different plasma-chemical processes occurring in oxygen low-temperature plasma which brings limitation to the maximum SDO yield and to the lifetime of the SDO in an electric discharge and its afterglow. Quite recently obtained results on gain and output characteristics of DOIL and some projects aimed at the development of high-power DOIL

  9. Paraffin as oxygen vector modulates tyrosine phenol lyase production by Citrobacter freundii MTCC 2424.

    Science.gov (United States)

    Azmi, Wamik; Kumar, Ajay; Dev, Varun

    2013-06-01

    The efficiency of three oxygen-vectors liquid paraffin, silicone oil and n-dodecane in the production of tyrosine phenol lyase (TPL) by Citrobacter freundii MTCC 2424 was evaluated at 4% (v/v) concentration. The liquid paraffin as oxygenvectors was found to exhibit a stimulatory effect on TPL synthesis. The liquid paraffin at 6% (v/v) resulted in 34% increase in the TPL synthesis accompanied by a 13% increase in the production of cell mass at a 10 L scale. This improvement in TPL and cell mass production in the presence of liquid paraffin can be related to the fact that liquid paraffin was capable of maintaining dissolved O2 concentration above 28% throughout the course of the fermentation. Maintenance of the dissolved O2 concentration above 28% could be viewed in terms of an adequate oxygen supply to the rapidly dividing cells of the bacterium, which in turn resulted in enhanced synthesis of TPL and cell mass.

  10. Reactive oxygen species production, induced by atmospheric modification, alter conidial quality of Beauveria bassiana.

    Science.gov (United States)

    Pérez-Guzmán, D; Montesinos-Matías, R; Arce-Cervantes, O; Gómez-Quiroz, L E; Loera, O; Garza-López, P M

    2016-08-01

    The aim of this study was to determine the relationship between reactive oxygen species (ROS) production and conidial infectivity in Beauveria bassiana. Beauveria bassiana Bb 882.5 was cultured in solid-state culture (SSC) using rice under three oxygen conditions (21%, or pulses at 16 and 26%). Hydrophobicity was determined using exclusion phase assay. Bioassays with larvae or adults of Tenebrio molitor allowed the measurements of infectivity parameters. A fluorometric method was used for ROS quantification (superoxide and total peroxides). NADPH oxidase (NOX) activity was determined by specific inhibition. Conidial hydrophobicity decreased by O2 pulses. Mortality of larvae was only achieved with conidia harvested from cultures under 21% O2 ; whereas for adult insects, the infectivity parameters deteriorated in conidia obtained after pulses at 16 and 26% O2 . At day 7, ROS production increased after 16 and 26% O2 treatments. NOX activity induced ROS production at early stages of the culture. Modification of atmospheric oxygen increases ROS production, reducing conidial quality and infectivity. This is the first study in which conidial infectivity and ROS production in B. bassiana has been related, enhancing the knowledge of the effect of O2 pulses in B. bassiana. © 2016 The Society for Applied Microbiology.

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

    Directory of Open Access Journals (Sweden)

    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.

  12. Relationship between work rate and oxygen uptake in mitochondrial myopathy during ramp-incremental exercise

    Directory of Open Access Journals (Sweden)

    A.C. Gimenes

    2011-04-01

    Full Text Available We determined the response characteristics and functional correlates of the dynamic relationship between the rate (Δ of oxygen consumption ( O2 and the applied power output (work rate = WR during ramp-incremental exercise in patients with mitochondrial myopathy (MM. Fourteen patients (7 males, age 35.4 ± 10.8 years with biopsy-proven MM and 10 sedentary controls (6 males, age 29.0 ± 7.8 years took a ramp-incremental cycle ergometer test for the determination of the O2 on-exercise mean response time (MRT and the gas exchange threshold (GET. The ΔO2/ΔWR slope was calculated up to GET (S1, above GET (S2 and over the entire linear portion of the response (S T. Knee muscle endurance was measured by isokinetic dynamometry. As expected, peak O2 and muscle performance were lower in patients than controls (P O2/ΔWR than controls, especially the S2 component (6.8 ± 1.5 vs 10.3 ± 0.6 mL·min-1·W-1, respectively; P O2/ΔWR (S T and muscle endurance, MRT-O2, GET and peak O2 in MM patients (P O2/ΔWR below 8 mL·min-1·W-1 had severely reduced peak O2 values (O2 had lower ΔO2/ΔWR (P O2/ΔWR is typically reduced in patients with MM, being related to increased functional impairment and higher cardiopulmonary stress.

  13. Using micro-patterned sensors and cell self-assembly for measuring the oxygen consumption rate of single cells

    International Nuclear Information System (INIS)

    Etzkorn, James R; Parviz, Babak A; Wu, Wen-Chung; Tian, Zhiyuan; Kim, Prince; Jang, Sei-Hum; Jen, Alex K-Y; Meldrum, Deirdre R

    2010-01-01

    We present a method for self-assembling arrays of live single cells on a glass chip using a photopatternable polymer to form micro-traps. We have studied the single-cell self-assembly method and optimized the process to obtain a 52% yield of single-trapped cells. We also report a method to measure the oxygen consumption rate of a single cell using micro-patterned sensors. These molecular oxygen sensors were fabricated around each micro-trap allowing optical interrogation of oxygen concentration in the immediate environment of the trapped cell. Micromachined micro-wells were then used to seal the trap, sensor and cell in order to determine the oxygen consumption rate of single cells. These techniques reported here add to the collection of tools for performing 'singe-cell' biology. An oxygen consumption rate of 1.05 ± 0.28 fmol min −1 was found for a data set consisting of 25 single A549 cells.

  14. empirical model for predicting rate of biogas production

    African Journals Online (AJOL)

    users

    Rate of biogas production using cow manure as substrate was monitored in two laboratory scale ... Biogas is a Gas obtained by anaerobic ... A. A. Adamu, Petroleum and Natural Gas Processing Department, Petroleum Training Institute, P.M.B..

  15. FORMING SELF-ASSEMBLED CELL ARRAYS AND MEASURING THE OXYGEN CONSUMPTION RATE OF A SINGLE LIVE CELL.

    Science.gov (United States)

    Etzkorn, James R; McQuaide, Sarah C; Anderson, Judy B; Meldrum, Deirdre R; Parviz, Babak A

    2009-06-01

    We report a method for forming arrays of live single cells on a chip using polymer micro-traps made of SU8. We have studied the toxicity of the microfabricated structures and the associated environment for two cell lines. We also report a method for measuring the oxygen consumption rate of a single cell using optical interrogation of molecular oxygen sensors placed in micromachined micro-wells by temporarily sealing the cells in the micro-traps. The new techniques presented here add to the collection of tools available for performing "single-cell" biology. A single-cell self-assembly yield of 61% was achieved with oxygen draw down rates of 0.83, 0.82, and 0.71 fmol/minute on three isolated live A549 cells.

  16. Dosimetric measurement of the disintegration rate of fission products

    International Nuclear Information System (INIS)

    Solymosi, J.; Nagy, L.G.; Zagyvai, P.

    1992-01-01

    Investigations on the disintegration rate of fission products of 238 U and 239 Pu are presented. The intensity of the β-and γ-radiation of fission products were measured continously in an interval of 1-1300 hours following the fission, offering the possibility for determining the general and specific characteristics of the individual fission products. A universal measuring procedure was elaborated for the rapid in situ determination of the dosimetric features of fission products, which is suitable for the accurate evaluation and prediction of external absorbed dose even in case of fission products of various origin and unknown composition. (author) 6 refs.; 7 figs.; 1 tab

  17. Comparison of Iron and Tungsten Based Oxygen Carriers for Hydrogen Production Using Chemical Looping Reforming

    Science.gov (United States)

    Khan, M. N.; Shamim, T.

    2017-08-01

    Hydrogen production by using a three reactor chemical looping reforming (TRCLR) technology is an innovative and attractive process. Fossil fuels such as methane are the feedstocks used. This process is similar to a conventional steam-methane reforming but occurs in three steps utilizing an oxygen carrier. As the oxygen carrier plays an important role, its selection should be done carefully. In this study, two oxygen carrier materials of base metal iron (Fe) and tungsten (W) are analysed using a thermodynamic model of a three reactor chemical looping reforming plant in Aspen plus. The results indicate that iron oxide has moderate oxygen carrying capacity and is cheaper since it is abundantly available. In terms of hydrogen production efficiency, tungsten oxide gives 4% better efficiency than iron oxide. While in terms of electrical power efficiency, iron oxide gives 4.6% better results than tungsten oxide. Overall, a TRCLR system with iron oxide is 2.6% more efficient and is cost effective than the TRCLR system with tungsten oxide.

  18. A CENSUS OF OXYGEN IN STAR-FORMING GALAXIES: AN EMPIRICAL MODEL LINKING METALLICITIES, STAR FORMATION RATES, AND OUTFLOWS

    International Nuclear Information System (INIS)

    Zahid, H. J.; Dima, G. I.; Kewley, L. J.; Erb, D. K.; Davé, R.

    2012-01-01

    In this contribution, we present the first census of oxygen in star-forming galaxies in the local universe. We examine three samples of galaxies with metallicities and star formation rates (SFRs) at z = 0.07, 0.8, and 2.26, including the Sloan Digital Sky Survey (SDSS) and DEEP2 survey. We infer the total mass of oxygen produced and mass of oxygen found in the gas-phase from our local SDSS sample. The star formation history is determined by requiring that galaxies evolve along the relation between stellar mass and SFR observed in our three samples. We show that the observed relation between stellar mass and SFR for our three samples is consistent with other samples in the literature. The mass-metallicity relation is well established for our three samples, and from this we empirically determine the chemical evolution of star-forming galaxies. Thus, we are able to simultaneously constrain the SFRs and metallicities of galaxies over cosmic time, allowing us to estimate the mass of oxygen locked up in stars. Combining this work with independent measurements reported in the literature, we conclude that the loss of oxygen from the interstellar medium of local star-forming galaxies is likely to be a ubiquitous process with the oxygen mass loss scaling (almost) linearly with stellar mass. We estimate the total baryonic mass loss and argue that only a small fraction of the baryons inferred from cosmological observations accrete onto galaxies.

  19. Real-time monitoring of specific oxygen uptake rates of embryonic stem cells in a microfluidic cell culture device.

    Science.gov (United States)

    Super, Alexandre; Jaccard, Nicolas; Cardoso Marques, Marco Paulo; Macown, Rhys Jarred; Griffin, Lewis Donald; Veraitch, Farlan Singh; Szita, Nicolas

    2016-09-01

    Oxygen plays a key role in stem cell biology as a signaling molecule and as an indicator of cell energy metabolism. Quantification of cellular oxygen kinetics, i.e. the determination of specific oxygen uptake rates (sOURs), is routinely used to understand metabolic shifts. However current methods to determine sOUR in adherent cell cultures rely on cell sampling, which impacts on cellular phenotype. We present real-time monitoring of cell growth from phase contrast microscopy images, and of respiration using optical sensors for dissolved oxygen. Time-course data for bulk and peri-cellular oxygen concentrations obtained for Chinese hamster ovary (CHO) and mouse embryonic stem cell (mESCs) cultures successfully demonstrated this non-invasive and label-free approach. Additionally, we confirmed non-invasive detection of cellular responses to rapidly changing culture conditions by exposing the cells to mitochondrial inhibiting and uncoupling agents. For the CHO and mESCs, sOUR values between 8 and 60 amol cell(-1) s(-1) , and 5 and 35 amol cell(-1) s(-1) were obtained, respectively. These values compare favorably with literature data. The capability to monitor oxygen tensions, cell growth, and sOUR, of adherent stem cell cultures, non-invasively and in real time, will be of significant benefit for future studies in stem cell biology and stem cell-based therapies. © 2016 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. BIG-10 fission product generation and reaction rates

    International Nuclear Information System (INIS)

    Rogers, J.W.

    1976-01-01

    Fission product generation rates for high quality fission foils and reaction rates of nonfission foils have been measured by gamma ray activation analyses. These foils were irradiated in the BIG-10 facility and the activities were measured by NaI counting techniques

  1. Temperature dependence of electrocatalytic and photocatalytic oxygen evolution reaction rates using NiFe oxide

    KAUST Repository

    Nurlaela, Ela; Shinagawa, Tatsuya; Qureshi, Muhammad; Dhawale, Dattatray Sadashiv; Takanabe, Kazuhiro

    2016-01-01

    The present work compares oxygen evolution reaction (OER) in electrocatalysis and photocatalysis in aqueous solutions using nanostructured NiFeOx as catalysts. The impacts of pH and reaction temperature on the electrocatalytic and photocatalytic OER

  2. Can the cerebral metabolic rate of oxygen be estimated with near-infrared spectroscopy?

    International Nuclear Information System (INIS)

    Boas, D A; Strangman, G; Culver, J P; Hoge, R D; Jasdzewski, G; Poldrack, R A; Rosen, B R; Mandeville, J B

    2003-01-01

    We have measured the changes in oxy-haemoglobin and deoxy-haemoglobin in the adult human brain during a brief finger tapping exercise using near-infrared spectroscopy (NIRS). The cerebral metabolic rate of oxygen (CMRO 2 ) can be estimated from these NIRS data provided certain model assumptions. The change in CMRO 2 is related to changes in the total haemoglobin concentration, deoxy-haemoglobin concentration and blood flow. As NIRS does not provide a measure of dynamic changes in blood flow during brain activation, we relied on a Windkessel model that relates dynamic blood volume and flow changes, which has been used previously for estimating CMRO 2 from functional magnetic resonance imaging (fMRI) data. Because of the partial volume effect we are unable to quantify the absolute changes in the local brain haemoglobin concentrations with NIRS and thus are unable to obtain an estimate of the absolute CMRO 2 change. An absolute estimate is also confounded by uncertainty in the flow-volume relationship. However, the ratio of the flow change to the CMRO 2 change is relatively insensitive to these uncertainties. For the finger tapping task, we estimate a most probable flow-consumption ratio ranging from 1.5 to 3 in agreement with previous findings presented in the literature, although we cannot exclude the possibility that there is no CMRO 2 change. The large range in the ratio arises from the large number of model parameters that must be estimated from the data. A more precise estimate of the flow-consumption ratio will require better estimates of the model parameters or flow information, as can be provided by combining NIRS with fMRI

  3. Effect of wearing clothes on oxygen uptake and ratings of perceived exertion while swimming.

    Science.gov (United States)

    Choi, S W; Kurokawa, T; Ebisu, Y; Kikkawa, K; Shiokawa, M; Yamasaki, M

    2000-07-01

    For a comparative study between swimming in swimwear (control-sw) and swimming in clothes (clothes-sw), oxygen uptake (VO2) and ratings of perceived exertion (RPE) were measured. The subjects were six male members of a university swimming team. Three swimming strokes--the breaststroke, the front crawl stroke and the elementary backstroke--were applied. With regards to clothes-sw, swimmers wore T-shirts, sportswear (shirt and pants) over swimwear and running shoes. In both cases of control-sw and clothes-sw, the VO2 was increased exponentially with increased swimming speed. The VO2 of the subjects during the clothed tests did not exceed 1.4 times of that in the case of control-sw at swimming speeds below 0.3 m/s. As swimming speeds increased, VO2 difference in both cases increased. Consequently, VO2 in the clothed tests was equal to 1.5-1.6 times and 1.5-1.8 times of that in the swimwear tests at speeds of 0.5 and 0.7 m/s, respectively. At speeds below 0.6 m/s in clothes-sw, the breaststroke showed lower VO2 than the front crawl stroke, and the elementary backstroke showed higher VO2 than the other two swimming strokes. RPE increased linearly with %peak VO2. In addition, any RPE differences among the three swimming strokes were not shown in the control-sw tests. At an exercise intensity above 60 %peak VO2, clothed swimmers showed slightly higher RPE in the front crawl stroke compared to that in the two other swimming strokes.

  4. Hydrodeoxygenation of aliphatic and aromatic oxygenates on sulphided catalysts for production of second generation biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Senol, O.I.

    2007-07-01

    Environmental concerns and diminishing petroleum reserves have increased the importance of biofuels for traffic fuel applications. Second generation biofuels produced from wood, vegetable oils and animal fats have been considered promising for delivering biofuels in large amount with low production cost. The abundance of oxygen in the form of various aliphatic and aromatic oxygenates decreases the quality of biofuels, however, and therefore the oxygen content of biofuels must be reduced. Upgrading of biofuels can be achieved by hydrodeoxygenation (HDO), which is similar to hydrodesulphurisation in oil refining. In HDO, oxygen-containing compounds are converted to hydrocarbons by eliminating oxygen in the form of water in the presence of hydrogen and a sulphided catalyst. Due to the low sulphur content of biofuels, a sulphiding agent is typically added to the HDO feed to maintain activity and stability of the catalyst. The aim of this work was to investigate HDO using aliphatic and aromatic oxygenates as model compounds on sulphided NiMo/gamma-Al{sub 2}O3 and CoMo/gamma-Al{sub 2}O3 catalysts. The effects of side product, water, and of sulphiding agents, H{sub 2}S and CS{sub 2}, on HDO were determined. The primary focus was on the HDO of aliphatic oxygenates, because a reasonable amount of data regarding the HDO of aromatic oxygenates already exists. The HDO of aliphatic esters produced hydrocarbons from intermediate alcohol, carboxylic acid, aldehyde and ether compounds. A few sulphur-containing compounds were also detected in trace amounts, and their formation caused desulphurisation of the catalysts. Hydrogenation reactions and acid-catalysed reactions (dehydration, hydrolysis, esterification, E{sub 2} elimination and SN{sub 2} nucleophilic substitution) played a major role in the HDO of aliphatic oxygenates. The NiMo catalyst showed a higher activity for HDO and hydrogenation reactions than the CoMo catalyst, but both catalysts became deactivated because of

  5. Dissolved natural organic matter (NOM) impacts photosynthetic oxygen production and electron transport in coontail Ceratophyllum demersum

    International Nuclear Information System (INIS)

    Pflugmacher, S.; Pietsch, C.; Rieger, W.; Steinberg, C.E.W.

    2006-01-01

    Dissolved natural organic matter (NOM) is dead organic matter exceeding, in freshwater systems, the concentration of organic carbon in all living organisms by far. 80-90% (w/w) of the NOM is made up of humic substances (HS). Although NOM possesses several functional groups, a potential effect on aquatic organisms has not been studied. In this study, direct effects of NOM from various origins on physiological and biochemical functions in the aquatic plant Ceratophyllum demersum are presented. Environmentally relevant concentrations of NOM cause inhibitory effects on the photosynthetic oxygen production of C. demersum. Various NOM sources and the synthetic humic substance HS1500 inhibit the photosynthetic oxygen production of the plant as observed with 1-amino-anthraquinone, a known inhibitor of plant photosynthesis. 1-Aminoanthraquinone may serve as an analogue for the quinoid structures in NOM and HS. Most likely, the effects of NOM may be related to quinoid structures and work downstream of photosynthesis at photosystem (PS) II

  6. Measurement of the variable track-etch rate of hydrogen, carbon and oxygen Ions in CR-39

    International Nuclear Information System (INIS)

    Lengar, I.; Skvarc, J.; Ilic, R.

    2003-01-01

    The ratio of the track-etch rate to the bulk-etch rate for hydrogen, carbon and oxygen ions was studied for the CR-39 detector with addition of dioctylphthalate. The response was reconstructed from etch-pit growth curves obtained by the multi-step etching technique. A theoretical analysis of the correctness of the method due to the 'missing track segment' is assessed and utilisation of the results obtained for the calibration of fast neutron dosimetry is discussed. (author)

  7. Norwegian resource policy: The production rate for Norwegian petroleum resources

    International Nuclear Information System (INIS)

    Schreiner, P.

    1995-01-01

    Petroleum activities have become a large industry in Norway. This has led to extensive changes in Norwegian economy and society. In the public debate on this activity there has been little discussion of what would be the most profitable production rate. However, it is generally agreed that the great wealth implied by the petroleum resources must be managed in ways suitable to both present and coming generations. This report discusses the production rate based on the following questions: (1) How high can the production rate be before the petroleum activities and the expenditure of the income from them influence the remaining Norwegian economy too strongly? (2) How much of this wealth should reasonably be used by present generations and how much should be left for future generations? There is much to gain from a high tempo and from relocating some of the petroleum wealth. The possibilities of influencing the production rate are mainly connected with the allotments of production licences. The consequences of uncertainties in the petroleum activities for the choice of exploitation tempo are unclear. The environment is not much affected by the production rate. The contractor activity has become Norway's largest industry. 42 refs., 14 figs., 2 tabs

  8. Engineering the oxygen sensing regulation results in an enhanced recombinant human hemoglobin production by Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Martinez Ruiz, José Luis; Liu, Lifang; Petranovic, Dina

    2015-01-01

    Efficient production of appropriate oxygen carriers for transfusions (blood substitutes or artificial blood) has been pursued for many decades, and to date several strategies have been used, from synthetic polymers to cell-free hemoglobin carriers. The recent advances in the field of metabolic en...... the transcription factor HAP1, which resulted in an increase of the final recombinant active hemoglobin titer exceeding 7% of the total cellular protein....

  9. Influence of Power Modulation on Ozone Production Using an AC Surface Dielectric Barrier Discharge in Oxygen

    Czech Academy of Sciences Publication Activity Database

    Šimek, Milan; Pekárek, S.; Prukner, Václav

    2010-01-01

    Roč. 30, č. 5 (2010), s. 607-617 ISSN 0272-4324 R&D Projects: GA ČR(CZ) GA202/09/0176 Institutional research plan: CEZ:AV0Z20430508 Keywords : Ozone * Surface DBD * Oxygen * Production efficiency Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.798, year: 2010 http://www.springerlink.com/content/28539775w5243513/

  10. Productivity variations, oxygen minimum zone and their impact on organic enrichment in the sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Paropkari, A.L.

    of Somalia, the Arabian Peninsula, Iran, Pakistan and Eastern and Western shelves of India (except a part of inner shelf), irrespective of primary productivity variation (Fig. 3), is mainly ascribed to decomposition of organic matter in contact.... Nevertheless, moderate to very high concentrations of organic carbon (Fig. 1) are invariably associated with the entire slope sediments, forming a long and wide band in contact with oxygen minima from Saurashtra to the southern tip of India. It may...

  11. Location and limitation of cellulose production by Acetobacter xylinum established from oxygen profiles

    NARCIS (Netherlands)

    Verschuren, P.G.; Cardona, T.D.; Nout, M.J.R.; Gooijer, de K.D.; Heuvel, van den J.C.

    2000-01-01

    The static fermentation of coconut water sucrose by Acetobacter xylinum was carried out at initial pH's of 3.0, 4.0, 5.0 or 6.0. Cellulose was produced at the surface, and its production was most favourable at pH's 4.0 and 5.0. These pH values also allowed for optimal bacterial growth. Oxygen

  12. The role of biology in planetary evolution: cyanobacterial primary production in low‐oxygen Proterozoic oceans

    Science.gov (United States)

    Bryant, Donald A.; Macalady, Jennifer L.

    2016-01-01

    Summary Understanding the role of biology in planetary evolution remains an outstanding challenge to geobiologists. Progress towards unravelling this puzzle for Earth is hindered by the scarcity of well‐preserved rocks from the Archean (4.0 to 2.5 Gyr ago) and Proterozoic (2.5 to 0.5 Gyr ago) Eons. In addition, the microscopic life that dominated Earth's biota for most of its history left a poor fossil record, consisting primarily of lithified microbial mats, rare microbial body fossils and membrane‐derived hydrocarbon molecules that are still challenging to interpret. However, it is clear from the sulfur isotope record and other geochemical proxies that the production of oxygen or oxidizing power radically changed Earth's surface and atmosphere during the Proterozoic Eon, pushing it away from the more reducing conditions prevalent during the Archean. In addition to ancient rocks, our reconstruction of Earth's redox evolution is informed by our knowledge of biogeochemical cycles catalysed by extant biota. The emergence of oxygenic photosynthesis in ancient cyanobacteria represents one of the most impressive microbial innovations in Earth's history, and oxygenic photosynthesis is the largest source of O 2 in the atmosphere today. Thus the study of microbial metabolisms and evolution provides an important link between extant biota and the clues from the geologic record. Here, we consider the physiology of cyanobacteria (the only microorganisms capable of oxygenic photosynthesis), their co‐occurrence with anoxygenic phototrophs in a variety of environments and their persistence in low‐oxygen environments, including in water columns as well as mats, throughout much of Earth's history. We examine insights gained from both the rock record and cyanobacteria presently living in early Earth analogue ecosystems and synthesize current knowledge of these ancient microbial mediators in planetary redox evolution. Our analysis supports the hypothesis that anoxygenic

  13. The impact of the oxygen scavenger on the dose-rate dependence and dose sensitivity of MAGIC type polymer gels

    Science.gov (United States)

    Khan, Muzafar; Heilemann, Gerd; Kuess, Peter; Georg, Dietmar; Berg, Andreas

    2018-03-01

    Recent developments in radiation therapy aimed at more precise dose delivery along with higher dose gradients (dose painting) and more efficient dose delivery with higher dose rates e.g. flattening filter free (FFF) irradiation. Magnetic-resonance-imaging based polymer gel dosimetry offers 3D information for precise dose delivery techniques. Many of the proposed polymer gels have been reported to exhibit a dose response, measured as relaxation rate ΔR2(D), which is dose rate dependent. A lack of or a reduced dose-rate sensitivity is very important for dosimetric accuracy, especially with regard to the increasing clinical use of FFF irradiation protocols with LINACs at high dose rates. Some commonly used polymer gels are based on Methacrylic-Acid-Gel-Initiated-by-Copper (MAGIC). Here, we report on the dose sensitivity (ΔR2/ΔD) of MAGIC-type gels with different oxygen scavenger concentration for their specific dependence on the applied dose rate in order to improve the dosimetric performance, especially for high dose rates. A preclinical x-ray machine (‘Yxlon’, E  =  200 kV) was used for irradiation to cover a range of dose rates from low \\dot{D} min  =  0.6 Gy min-1 to high \\dot{D} max  =  18 Gy min-1. The dose response was evaluated using R2-imaging of the gel on a human high-field (7T) MR-scanner. The results indicate that all of the investigated dose rates had an impact on the dose response in polymer gel dosimeters, being strongest in the high dose region and less effective for low dose levels. The absolute dose rate dependence \\frac{(Δ R2/Δ D)}{Δ \\dot{D}} of the dose response in MAGIC-type gel is significantly reduced using higher concentrations of oxygen scavenger at the expense of reduced dose sensitivity. For quantitative dose evaluations the relative dose rate dependence of a polymer gel, normalized to its sensitivity is important. Based on this normalized sensitivity the dose rate sensitivity was reduced distinctly

  14. Oxygen at nanomolar levels reversibly suppresses process rates and gene expression in anammox and denitrification in the oxygen minimum zone off Northern Chil

    DEFF Research Database (Denmark)

    Dalsgaard, Tage; Stewart, Frank J.; Thamdrup, Bo

    2014-01-01

    at nanomolar levels affects anammox and denitrification rates and the transcription of nitrogen cycle genes in the anoxic OMZ off Chile. Rates of anammox and denitrification were reversibly suppressed, most likely at the enzyme level. Fiftypercent inhibition of N2 and N2O production by denitrification...

  15. A foundational methodology for determining system static complexity using notional lunar oxygen production processes

    Science.gov (United States)

    Long, Nicholas James

    This thesis serves to develop a preliminary foundational methodology for evaluating the static complexity of future lunar oxygen production systems when extensive information is not yet available about the various systems under consideration. Evaluating static complexity, as part of a overall system complexity analysis, is an important consideration in ultimately selecting a process to be used in a lunar base. When system complexity is higher, there is generally an overall increase in risk which could impact the safety of astronauts and the economic performance of the mission. To evaluate static complexity in lunar oxygen production, static complexity is simplified and defined into its essential components. First, three essential dimensions of static complexity are investigated, including interconnective complexity, strength of connections, and complexity in variety. Then a set of methods is developed upon which to separately evaluate each dimension. Q-connectivity analysis is proposed as a means to evaluate interconnective complexity and strength of connections. The law of requisite variety originating from cybernetic theory is suggested to interpret complexity in variety. Secondly, a means to aggregate the results of each analysis is proposed to create holistic measurement for static complexity using the Single Multi-Attribute Ranking Technique (SMART). Each method of static complexity analysis and the aggregation technique is demonstrated using notional data for four lunar oxygen production processes.

  16. Determination of relative CMRO2 from CBF and BOLD changes: significant increase of oxygen consumption rate during visual stimulation

    DEFF Research Database (Denmark)

    Kim, S.G.; Rostrup, Egill; Larsson, H.B.

    1999-01-01

    signal changes were measured simultaneously using the flow-sensitive alternating inversion recovery (FAIR) technique. During hypercapnia established by an end-tidal CO2 increase of 1.46 kPa, CBF in the visual cortex increased by 47.3 +/- 17.3% (mean +/- SD; n = 9), and deltaR2* was -0.478 +/- 0.147 sec......The blood oxygenation level-dependent (BOLD) effect in functional magnetic resonance imaging depends on at least partial uncoupling between cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) changes. By measuring CBF and BOLD simultaneously, the relative change in CMRO2 can...

  17. Validity of using a 3-dimensional PET scanner during inhalation of 15O-labeled oxygen for quantitative assessment of regional metabolic rate of oxygen in man

    Science.gov (United States)

    Hori, Yuki; Hirano, Yoshiyuki; Koshino, Kazuhiro; Moriguchi, Tetsuaki; Iguchi, Satoshi; Yamamoto, Akihide; Enmi, Junichiro; Kawashima, Hidekazu; Zeniya, Tsutomu; Morita, Naomi; Nakagawara, Jyoji; Casey, Michael E.; Iida, Hidehiro

    2014-09-01

    Use of 15O labeled oxygen (15O2) and positron emission tomography (PET) allows quantitative assessment of the regional metabolic rate of oxygen (CMRO2) in vivo, which is essential to understanding the pathological status of patients with cerebral vascular and neurological disorders. The method has, however, been challenging, when a 3D PET scanner is employed, largely attributed to the presence of gaseous radioactivity in the trachea and the inhalation system, which results in a large amount of scatter and random events in the PET assessment. The present study was intended to evaluate the adequacy of using a recently available commercial 3D PET scanner in the assessment of regional cerebral radioactivity distribution during an inhalation of 15O2. Systematic experiments were carried out on a brain phantom. Experiments were also performed on a healthy volunteer following a recently developed protocol for simultaneous assessment of CMRO2 and cerebral blood flow, which involves sequential administration of 15O2 and C15O2. A particular intention was to evaluate the adequacy of the scatter-correction procedures. The phantom experiment demonstrated that errors were within 3% at the practically maximum radioactivity in the face mask, with the greatest radioactivity in the lung. The volunteer experiment demonstrated that the counting rate was at peak during the 15O gas inhalation period, within a verified range. Tomographic images represented good quality over the entire FOV, including the lower part of the cerebral structures and the carotid artery regions. The scatter-correction procedures appeared to be important, particularly in the process to compensate for the scatter originating outside the FOV. Reconstructed images dramatically changed if the correction was carried out using inappropriate procedures. This study demonstrated that accurate reconstruction could be obtained when the scatter compensation was appropriately carried out. This study also suggested the

  18. Oxygen toxicity

    Directory of Open Access Journals (Sweden)

    C. A. van der Westhuizen

    1990-07-01

    Full Text Available Oxygen has been discovered about 200 years ago. Since then the vital physiological involvement of oxygen in various biologi­cal processes, mainly energy production, has been established. However, in the body molecular oxygen can be converted to toxic oxygen metabolites such as superoxide anion, hydrogen peroxide, the hydroxyl radical and singlet oxygen. These toxic metabolites are produced mainly in the mitochondria, plasma membranes and endoplasmic reticulum.

  19. Detection of Cyclooxygenase-2-Derived Oxygenation Products of the Endogenous Cannabinoid 2-Arachidonoylglycerol in Mouse Brain.

    Science.gov (United States)

    Morgan, Amanda J; Kingsley, Philip J; Mitchener, Michelle M; Altemus, Megan; Patrick, Toni A; Gaulden, Andrew D; Marnett, Lawrence J; Patel, Sachin

    2018-05-09

    Cyclooxygenase-2 (COX-2) catalyzes the formation of prostaglandins, which are involved in immune regulation, vascular function, and synaptic signaling. COX-2 also inactivates the endogenous cannabinoid (eCB) 2-arachidonoylglycerol (2-AG) via oxygenation of its arachidonic acid backbone to form a variety of prostaglandin glyceryl esters (PG-Gs). Although this oxygenation reaction is readily observed in vitro and in intact cells, detection of COX-2-derived 2-AG oxygenation products has not been previously reported in neuronal tissue. Here we show that 2-AG is metabolized in the brain of transgenic COX-2-overexpressing mice and mice treated with lipopolysaccharide to form multiple species of PG-Gs that are detectable only when monoacylglycerol lipase is concomitantly blocked. Formation of these PG-Gs is prevented by acute pharmacological inhibition of COX-2. These data provide evidence that neuronal COX-2 is capable of oxygenating 2-AG to form a variety PG-Gs in vivo and support further investigation of the physiological functions of PG-Gs.

  20. High-rate deposition of photocatalytic TiO2 films by oxygen plasma assist reactive evaporation method

    International Nuclear Information System (INIS)

    Sakai, Tetsuya; Kuniyoshi, Yuji; Aoki, Wataru; Ezoe, Sho; Endo, Tatsuya; Hoshi, Yoichi

    2008-01-01

    High-rate deposition of titanium dioxide (TiO 2 ) film was attempted using oxygen plasma assisted reactive evaporation (OPARE) method. Photocatalytic properties of the film were investigated. During the deposition, the substrate temperature was fixed at 400 deg. C. The film deposition rate can be increased by increasing the supply of titanium atoms to the substrate, although oversupply of the titanium atoms causes oxygen deficiency in the films, which limits the deposition rate. The film structure depends strongly on the supply ratio of oxygen molecules to titanium atoms O 2 /Ti and changes from anatase to rutile structure as the O 2 /Ti supply ratio increased. Consequently, the maximum deposition rates of 77.0 nm min -1 and 145.0 nm min -1 were obtained, respectively, for the anatase and rutile film. Both films deposited at such high rates showed excellent hydrophilicity and organic decomposition performance. Even the film with rutile structure deposited at 145.0 nm min -1 had a contact angle of less than 2.5 deg. by UV irradiation for 5.0 h and an organics-decomposition performance index of 8.9 [μmol l -1 min -1 ] for methylene blue

  1. Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers

    Science.gov (United States)

    Anderson, I. C.; Levine, J. S.

    1986-01-01

    An account is given of the atmospheric chemical and photochemical effects of biogenic nitric and nitrous oxide emissions. The magnitude of the biogenic emission of NO is noted to remain uncertain. Possible soil sources of NO and N2O encompass nitrification by autotropic and heterotropic nitrifiers, denitrification by nitrifiers and denitrifiers, nitrate respiration by fermenters, and chemodenitrification. Oxygen availability is the primary determinant of these organisms' relative rates of activity. The characteristics of this major influence are presently investigated in light of the effect of oxygen partial pressure on NO and N2O production by a wide variety of common soil-nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The results obtained indicate that aerobic soils are primary sources only when there is sufficient moisture to furnish anaerobic microsites for denitrification.

  2. Filterability of corrosion products formed between carbon steel and water. Influence of temperature and oxygen content

    International Nuclear Information System (INIS)

    Kelen, T.; Falk, I.

    1975-09-01

    A laboratory investigation has been made for the purpose of studying the influence of temperature and oxygen content on the filterability of corrosion products formed between carbon-steel and water. The experiments were performed in a high temperature loop where the water is initially heated in a pre-heater, then cooled and finally filtered. The corrosion products were transferred to thewater from a carbon-steel surface that had previously been neutron activated and the amount of iron present was determined from measurements of the γ-radiation emitted by Fe-59. Filterability was then computed as the ratio between the total amount of iron in the water phase and the amount of iron retained on the filter. The investigation covers a series of experiments at filtering temperatures of 20, 90 and 160 dec G, pre-heater temperatures up to 300 deg C and oxygen contents of 10 and 300 ppb O 2 . In addition the extent of iron deposition in the pre-heater and heat regulator has been determined after each series of experiments. Filterability exhibited a pronounced dependence upon both the filter and pre-heater temperatures and also upon the oxygen content. Among the conclusions to which the results lead is the observation that a strict comparison of filterability values for the fraction of corrosion products in cooled water samples is impossible when these are taken from 1) different sections of a high temperature system 2) a single sampling point while the system is being run up 3) two separate systems (e.g. steam boilers) operated at different temperatures 4) two separate systems operated at different oxygen contents. It accordingly appears advizable to restrict the use of cold-filtered samples from conventional steam-raising plants to the comparison of values relating to a single sampling point under constant operating conditions. (author)

  3. A prospective population study of resting heart rate and peak oxygen uptake (the HUNT Study, Norway.

    Directory of Open Access Journals (Sweden)

    Javaid Nauman

    Full Text Available OBJECTIVES: We assessed the prospective association of resting heart rate (RHR at baseline with peak oxygen uptake (VO(2peak 23 years later, and evaluated whether physical activity (PA could modify this association. BACKGROUND: Both RHR and VO(2peak are strong and independent predictors of cardiovascular morbidity and mortality. However, the association of RHR with VO(2peak and modifying effect of PA have not been prospectively assessed in population studies. METHODS: In 807 men and 810 women free from cardiovascular disease both at baseline (1984-86 and follow-up 23 years later, RHR was recorded at both occasions, and VO(2peak was measured by ergospirometry at follow-up. We used Generalized Linear Models to assess the association of baseline RHR with VO(2peak, and to study combined effects of RHR and self-reported PA on later VO(2peak. RESULTS: There was an inverse association of RHR at baseline with VO(2peak (p<0.01. Men and women with baseline RHR greater than 80 bpm had 4.6 mL.kg(-1.min(-1 (95% confidence interval [CI], 2.8 to 6.3 and 1.4 mL.kg(-1.min(-1 (95% CI, -0.4 to 3.1 lower VO(2peak at follow-up compared with men and women with RHR below 60 bpm at baseline. We found a linear association of change in RHR with VO(2peak (p=0.03, suggesting that a decrease in RHR over time is likely to be beneficial for cardiovascular fitness. Participants with low RHR and high PA at baseline had higher VO(2peak than inactive people with relatively high RHR. However, among participants with relatively high RHR and high PA at baseline, VO(2peak was similar to inactive people with relatively low RHR. CONCLUSION: RHR is an important predictor of VO(2peak, and serial assessments of RHR may provide useful and inexpensive information on cardiovascular fitness. The results suggest that high levels of PA may compensate for the lower VO(2peak associated with a high RHR.

  4. Comparative Photoelectrochemical Study of PEC Solar Cell Fabricated with n-TiO2 Photo-electrodes at Different Temperatures and under Different Oxygen Flow Rates

    International Nuclear Information System (INIS)

    Mishra, P.R.; Srivastava, O.N.; Shukla, P.K.

    2006-01-01

    Photoelectrochemical splitting of water induced by solar energy for hydrogen production has been studied in the present investigation. PEC solar cell was fabricated with n-TiO 2 photo-electrodes synthesized at different oxidation temperatures e.g. 700 C, 750 C, 800 C and 850 C under oxygen flow rate 200 ml/min, 350 ml/min and 500 ml/min. The optimum oxygen flow rate for all the temperatures was found to be 350 ml/min. This is therefore kept invariant for synthesis of electrodes at different temperatures. The photo-electrochemical characterization of the PEC cell was done in the three-electrode configuration, i.e Ti/n-TiO 2 /1M-NaOH/Pt. It has been observed that the optimum values of the PEC solar cell parameters are exhibited by the solar cell employing the photo-electrodes prepared at ∼7500 C. The XRD and SEM explorations revealed that the TiO 2 prepared at ∼7500 C is in the nano-metric range (∼100-150 nm). The TiO 2 films formed at this temperature has been found to exhibit optimum PEC solar cell parameters. The PEC parameters, like photocurrent density, photo-conversion efficiency and hydrogen production rate, with this photo-electrode correspond to 0.93 mA/cm 2 , 0.472% and 4.00 l/hm 2 respectively. (authors)

  5. Copepod egg production, moulting and growth rates and secondary production in the Skagerrak in August 1988

    DEFF Research Database (Denmark)

    Peterson, W.T.; Tiselius, P.; Kiørboe, Thomas

    1991-01-01

    Measurements of hydrography, chlorophyll, moulting rates of juvenile copepods and egg production rates of adult female copepods were made at eight stations along a transect across the Skagerrak. The goals of the study were to determine (i) if there were correlations between spatial variations...... in hydrography, phytoplankton and copepod production rates, (ii) if copepod egg production rates were correlated with juvenile growth rates, and (iii) if there was evidence of food-niche separation among co-occurring female copepods. The 200 km wide Skagerrak had a stratified water column in the center...... is similar to maximum rates known from laboratory studies, thus were probably not food-limited. Egg production rates were food-limited with the degree of limitation varying among species: 75% of maximum for Centropages typicus, 50% for Calanus finmarchicus, 30% for Paracalanus parvus and 15% for Acartia...

  6. Laser diagnostics of atomic hydrogen and oxygen production in rf and microwave plasma discharges

    International Nuclear Information System (INIS)

    Preppernau, B.L.

    1993-01-01

    The research for this thesis involved the application of two-photon allowed laser-induced fluorescence (TALIF) to the study of atomic hydrogen and oxygen production in industrial scale radio-frequency and microwave plasma discharge apparatus. Absolute atomic hydrogen concentration profiles were measured in a Gaseous Electronics Conference Reference Cell installed at Wright-Patterson AFB, Ohio operating with a simple H 2 discharge. Two-dimensional atomic hydrogen concentration profiles were also measured in an ASTEX HPMM microwave plasma diamond deposition reactor during actual diamond growth. In addition absolute atomic oxygen concentrations were measured in the ASTEX system. Particular attention as paid to refining the concentration calibration technique and in determining a correction to account for the collisional quenching of excited state fluorescence in high pressure gases

  7. Hydrogen-oxygen steam generator applications for increasing the efficiency, maneuverability and reliability of power production

    Science.gov (United States)

    Schastlivtsev, A. I.; Borzenko, V. I.

    2017-11-01

    The comparative feasibility study of the energy storage technologies showed good applicability of hydrogen-oxygen steam generators (HOSG) based energy storage systems with large-scale hydrogen production. The developed scheme solutions for the use of HOSGs for thermal power (TPP) and nuclear power plants (NPP), and the feasibility analysis that have been carried out have shown that their use makes it possible to increase the maneuverability of steam turbines and provide backup power supply in the event of failure of the main steam generating equipment. The main design solutions for the integration of hydrogen-oxygen steam generators into the main power equipment of TPPs and NPPs, as well as their optimal operation modes, are considered.

  8. Study and development of a fluorescence based sensor system for monitoring oxygen in wine production : the WOW project

    NARCIS (Netherlands)

    Trivellin, Nicola; Barbisan, Diego; Badocco, Denis; Pastore, Paolo; Meneghesso, Gaudenzio; Meneghini, Matteo; Zanoni, Enrico; Belgioioso, Giuseppe; Cenedese, Angelo

    2018-01-01

    The importance of oxygen in the winemaking process is widely known, as it affects the chemical aspects and therefore the organoleptic characteristics of the final product. Hence, it is evident the usefulness of a continuous and real-time measurements of the levels of oxygen in the various stages of

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

    Science.gov (United States)

    Salehmin, M N I; Annuar, M S M; Chisti, Y

    2013-11-01

    This review is focused on the production of microbial lipases by high cell density fermentation. Lipases are among the most widely used of the enzyme catalysts. Although lipases are produced by animals and plants, industrial lipases are sourced almost exclusively from microorganisms. Many of the commercial lipases are produced using recombinant species. Microbial lipases are mostly produced by batch and fed-batch fermentation. Lipases are generally secreted by the cell into the extracellular environment. Thus, a crude preparation of lipases can be obtained by removing the microbial cells from the fermentation broth. This crude cell-free broth may be further concentrated and used as is, or lipases may be purified from it to various levels. For many large volume applications, lipases must be produced at extremely low cost. High cell density fermentation is a promising method for low-cost production: it allows a high concentration of the biomass and the enzyme to be attained rapidly and this eases the downstream recovery of the enzyme. High density fermentation enhances enzyme productivity compared with the traditional submerged culture batch fermentation. In production of enzymes, a high cell density is generally achieved through fed-batch operation, not through perfusion culture which is cumbersome. The feeding strategies used in fed-batch fermentations for producing lipases and the implications of these strategies are discussed. Most lipase-producing microbial fermentations require oxygen. Oxygen transfer in such fermentations is discussed.

  10. Cerebral Metabolic Rate of Oxygen (CMRO2 ) Mapping by Combining Quantitative Susceptibility Mapping (QSM) and Quantitative Blood Oxygenation Level-Dependent Imaging (qBOLD).

    Science.gov (United States)

    Cho, Junghun; Kee, Youngwook; Spincemaille, Pascal; Nguyen, Thanh D; Zhang, Jingwei; Gupta, Ajay; Zhang, Shun; Wang, Yi

    2018-03-07

    To map the cerebral metabolic rate of oxygen (CMRO 2 ) by estimating the oxygen extraction fraction (OEF) from gradient echo imaging (GRE) using phase and magnitude of the GRE data. 3D multi-echo gradient echo imaging and perfusion imaging with arterial spin labeling were performed in 11 healthy subjects. CMRO 2 and OEF maps were reconstructed by joint quantitative susceptibility mapping (QSM) to process GRE phases and quantitative blood oxygen level-dependent (qBOLD) modeling to process GRE magnitudes. Comparisons with QSM and qBOLD alone were performed using ROI analysis, paired t-tests, and Bland-Altman plot. The average CMRO 2 value in cortical gray matter across subjects were 140.4 ± 14.9, 134.1 ± 12.5, and 184.6 ± 17.9 μmol/100 g/min, with corresponding OEFs of 30.9 ± 3.4%, 30.0 ± 1.8%, and 40.9 ± 2.4% for methods based on QSM, qBOLD, and QSM+qBOLD, respectively. QSM+qBOLD provided the highest CMRO 2 contrast between gray and white matter, more uniform OEF than QSM, and less noisy OEF than qBOLD. Quantitative CMRO 2 mapping that fits the entire complex GRE data is feasible by combining QSM analysis of phase and qBOLD analysis of magnitude. © 2018 International Society for Magnetic Resonance in Medicine.

  11. Evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii.

    Directory of Open Access Journals (Sweden)

    Alvaro Díaz-Barrera

    Full Text Available Alginates are polysaccharides used as food additives and encapsulation agents in biotechnology, and their functional properties depend on its molecular weight. In this study, different steady-states in continuous cultures of A. vinelandii were established to determine the effect of the dilution rate (D and the agitation rate on alginate production and expression of genes involved in alginate polymerization and depolymerization. Both, the agitation and dilution rates, determined the partitioning of the carbon utilization from sucrose into alginate and CO2 under oxygen-limiting conditions. A low D (0.07 h(-1 and 500 rpm resulted in the highest carbon utilization into alginate (25%. Quantitative real-time polymerase chain reaction was used to determine the transcription level of six genes involved in alginate polymerization and depolymerization. In chemostat cultures at 0.07 h(-1, the gene expression was affected by changes in the agitation rate. By increasing the agitation rate from 400 to 600 rpm, the algE7 gene expression decreased tenfold, whereas alyA1, algL and alyA2 gene expression increased between 1.5 and 2.8 times under similar conditions evaluated. Chemostat at 0.07 h(-1 showed a highest alginate molecular weight (580 kDa at 500 rpm whereas similar molecular weights (480 kDa were obtained at 400 and 600 rpm. The highest molecular weight was not explained by changes in the expression of alg8 and alg44 (genes involved in alginate polymerization. Nonetheless, a different expression pattern observed for lyases could explain the highest alginate molecular weight obtained. Overall, the results suggest that the control of alginate molecular weight in A. vinelandii cells growing in continuous mode is determined by a balance between the gene expression of intracellular and extracellular lyases in response to oxygen availability. These findings better our understanding of the biosynthesis of bacterial alginate and help us progress toward obtain

  12. Soil Production and Erosion Rates and Processes in Mountainous Landscapes

    Science.gov (United States)

    Heimsath, A. M.; DiBiase, R. A.; Whipple, K. X.

    2012-12-01

    We focus here on high-relief, steeply sloped landscapes from the Nepal Himalaya to the San Gabriels of California that are typically thought to be at a critical threshold of soil cover. Observations reveal that, instead, there are significant areas mantled with soil that fit the conceptual framework of a physically mobile layer derived from the underlying parent material with some locally-derived organic content. The extent and persistence of such soils depends on the long-term balance between soil production and erosion despite the perceived discrepancy between high erosion and low soil production rates. We present cosmogenic Be-10-derived soil production and erosion rates that show that soil production increases with catchment-averaged erosion, suggesting a feedback that enhances soil-cover persistence, even in threshold landscapes. Soil production rates do decline systematically with increasing soil thickness, but hint at the potential for separate soil production functions for different erosional regimes. We also show that a process transistion to landslide-dominated erosion results in thinner, patchier soils and rockier topography, but find that there is no sudden transition to bedrock landscapes. Our landslide modeling is combined with a detailed quantification of bedrock exposure for these steep, mountainous landscapes. We also draw an important conclusion connecting the physical processes producing and transporting soil and the chemical processes weathering the parent material by measuring parent material strength across three different field settings. We observe that parent material strength increases with overlying soil thickness and, therefore, the weathered extent of the saprolite. Soil production rates, thus, decrease with increasing parent material competence. These observation highlight the importance of quantifying hillslope hydrologic processes where such multi-facted measurements are made.

  13. Proton-induced production cross-sections and production rates of 41Ca from Ni

    International Nuclear Information System (INIS)

    Schnabel, C.; Synal, H.-A.; Gartenmann, P.; Santos-Arevalo, F.J.; Gomez-Martinez, I.; Suter, M.; Tarabischi, A.; Bastian, T.; Sudbrock, F.; Herpers, U.; Leya, I.; Gloris, M.; Michel, R.

    2004-01-01

    Proton-induced production cross-sections of 41 Ca from Ni are presented. Moreover, depth-dependent production rates of 41 Ca from Ni were determined in a meteoroid simulation experiment. Based on these data, modelled production rates of 41 Ca from Ni in iron meteoroids are presented as a function of depth and size. These data are relevant for modelling the production rate ratio of 41 Ca/ 36 Cl in metal phases of meteoroids and thus for the application of the 41 Ca- 36 Cl method to determine terrestrial ages of meteorites

  14. EFFECTS OF IMMOBILIZATION IN Ba-ALGINATE ON NITRILE-DEPENDENT OXYGEN UPTAKE RATES OF CANDIDA GUILLIERMONDII

    Directory of Open Access Journals (Sweden)

    Dias João Carlos Teixeira

    2001-01-01

    Full Text Available Yeast cells immobilized by entrapment in Ba-alginate gel were investigated for growth pattern and respiratory activity. The oxygen uptake rates (OUR of cells entrapped in gels with 4% alginate were 5.2 and 23% lower than the OUR of 2% alginate and free cells, respectively. The mass-transfer resistance offered by the matrix and growth of the entrapped cells determine a gradient of nutrients throughout the gel which is responsible for both a lower specific growth rate of immobilized cells with respect to that of free ones, and a heterogeneous biomass distribution, with progressively increasing cellular density from the inside to the outside of the matrix. Gel-matrix polymer concentration affected the maximum oxygen uptake of immobilized growing yeast cells.

  15. Investigation of OxProduction Rates in the Mexico City Metropolitan Area during MILAGRO

    Science.gov (United States)

    Dusanter, S.; Molina, L. T.; Stevens, P. S.

    2009-12-01

    Understanding the oxidative capacity of the atmosphere and the formation of secondary pollutants are important issues in atmospheric chemistry. For instance, the photochemical production of tropospheric ozone (O3) is of particular interest due to its detrimental effects on both human health and agricultural ecosystems. A detailed characterization of tropospheric O3 production rates will help in the development of effective control strategies. The 2006 Mexico City Metropolitan Area field campaign (MCMA-2006) was one of four components of MILAGRO (Megacity Initiative: Local And Global Research Observations) intended to collect information on the impact of megacity emissions on local, regional and global scales. In this presentation, rates of production of Ox (Ox = O3 + NO2) species during MCMA-2006 at the supersite T0 (Instituto Mexicano del Petroleo) will be presented using different approaches based on measured and modeled concentrations of ROx (OH + HO2 + RO2) radicals. In addition, we will examine both the reactivity of OH and the contribution of specific peroxy radicals to the oxidation rate of NO to estimate the contribution of groups of VOCs (alkanes, alkenes, aromatics, oxygenated and biogenic VOCs) to the total production rate of Ox species.

  16. Comparative study of activities in reactive oxygen species production/defense system in mitochondria of rat brain and liver, and their susceptibility to methylmercury toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Mori, N.; Hirayama, K. [Kumamoto University, School of Health Science, Kumamoto (Japan); Yasutake, A. [National Institute for Minamata Disease, Minamata (Japan)

    2007-11-15

    The involvement of oxidative stress has been suggested as a mechanism for neurotoxicity caused by methylmercury (MeHg), but the mechanism for MeHg selective toxicity in the central nervous system is still unclear. In this research, to clarify the mechanism of selective neurotoxicity caused by MeHg, the oxygen consumption levels, the reactive oxygen species (ROS) production rates and several antioxidant levels in mitochondria were compared among the cerebrum, cerebellum and liver of male Wistar rats. In addition, the alterations of these indexes were examined in MeHg-intoxicated rats (oral administration of 10 mg/kg day, for 5 days). Although the cerebrum and cerebellum in intact rats showed higher mitochondrial oxygen consumption levels and ROS production rates than the liver, glutathione peroxidase (GPX) and superoxide dismutase (SOD) activities were much lower in the cerebrum and cerebellum than in the liver. Especially, the cerebellum showed the highest oxygen consumption and ROS production rate and the lowest mitochondrial glutathione (GSH) levels among the tissues examined. In the MeHg-treated rats, decrease in the oxygen consumption and increase in the ROS generation were found only in the cerebellum mitochondria, despite a lower Hg accumulation in the mitochondrial fraction compared to the liver. Since MeHg treatment produced an enhancement of ROS generation in cerebellum mitochondria supplemented with succinate substrates, MeHg-induced oxidative stress might affect the complex II-III mediated pathway in the electron transfer chain in the cerebellum mitochondria. Our study suggested that inborn factors, high production system activity and low defense system activity of ROS in the brain, would relate to the high susceptibility of the central nervous system to MeHg toxicity. (orig.)

  17. Mechanism of pulse discharge production of iodine atoms from CF3I molecules for a chemical oxygen-iodine laser

    International Nuclear Information System (INIS)

    Kochetov, I V; Napartovich, A P; Vagin, N P; Yuryshev, N N

    2009-01-01

    The pulsed chemical oxygen-iodine laser (COIL) development is aimed at many new applications. Pulsed electric discharge is most effective in turning COIL operation into the pulse mode by instant production of iodine atoms. A numerical model is developed for simulations of the pulsed COIL initiated by an electric discharge. The model comprises a system of kinetic equations for neutral and charged species, electric circuit equation, gas thermal balance equation and the photon balance equation. Reaction rate coefficients for processes involving electrons are found by solving the electron Boltzmann equation, which is re-calculated in a course of computations when plasma parameters changed. The processes accounted for in the Boltzmann equation include excitation and ionization of atoms and molecules, dissociation of molecules, electron attachment processes, electron-ion recombination, electron-electron collisions, second-kind collisions and stepwise excitation of molecules. The last processes are particularly important because of a high singlet oxygen concentration in gas flow from the singlet oxygen chemical generator. Results of numerical simulations are compared with experimental laser pulse waveforms. It is concluded that there is satisfactory agreement between theory and the experiment. The prevailing mechanism of iodine atom formation from the CF 3 I donor in a very complex kinetic system of the COIL medium under pulse discharge conditions, based on their detailed numerical modelling and by comparing these results both with experimental results of other authors and their own experiments, is established. The dominant iodine atom production mechanism for conditions under study is the electron-impact dissociation of CF 3 I molecules. It was proved that in the conditions of the experiment the secondary chemical reactions with O atoms play an insignificant role.

  18. Production of alkyl-aromatics from light oxygenates over zeolite catalysts for bio-oil refining

    Science.gov (United States)

    Hoang, Trung Q.

    Upgrading of light oxygenates derived from biomass conversion, such as propanal and glycerol, to more valuable aromatics for biofuels has been demonstrated on zeolite catalysts. Aromatics with a high ratio of C 9/(C8+C7) and little benzene are produced at much higher yield from oxygenates than from olefins at mild conditions over HZSM-5. It is proposed that C9 aromatics are predominantly produced via acid-catalyzed aldol condensation. This reaction pathway is different from the pathway of propylene and other hydrocarbon aromatization that occurs via a hydrocarbon pool at more severe conditions with major aromatic products C6 and C7. In fact, investigation on the effect of crystallite size HZSM-5 has shown a higher ratio of C9/(C8+C 7) aromatics on small crystallite. This is due to faster removal of products from the shorter diffusion path length. As a result, a longer catalyst lifetime, less isomerization, and less cracking were observed on small crystallites. Beside crystallite size, pore geometry of zeolites was also found to significantly affect aromatic production for both conversion of propanal and glycerol. It is shown that the structure of the HZSM-22, with a one-dimensional and narrower channel system, restricts the formation of aromatics. In contrast, a higher yield of aromatic products is observed over HZSM-5 with its three-dimensional channel system. By increasing channel dimension and connectivity of the channels, increasing catalyst activity was also observed due to more accessible acid sites. It was also found that glycerol is highly active for dehydration on zeolites to produce high yields of acrolein (propenal), a high value chemical. To maximize aromatics from glycerol conversion, HZSM-5 and HY were found to be effective. A two-bed reactor of Pd/ZnO and HZSM-5 was used to first deoxygenate/hydrogenate glycerol over Pd/ZnO to intermediate oxygenates that can further aromatize on HZSM-5. The end results are very promising with significant improvement

  19. Production and decay rates of the iota meson

    International Nuclear Information System (INIS)

    Frank, M.; O'Donnell, P.J.; Toronto Univ., Ontario

    1984-01-01

    We correlate the results for the mass spectrum of low lying isoscalar-pseudoscalar mesons with the production decay rates from J/psi->γP, with P=eta 1 , eta' 1 , eta 2 and iota and study the radiative decays of the iota meson. We conclude that the iota meson has to be interpreted as having a strong gluonium component. (orig.)

  20. Evaluation of biogas production rate and biochemical changes in ...

    African Journals Online (AJOL)

    The rate of biogas generation and biochemical changes in pig dung used in a simple mobile biogas digester designed and constructed at the Department of Environmental Technology, Federal University of Technology Owerri, Nigeria were evaluated. Measurable gas production started 4 days after feeding the digester with ...

  1. Empirical Model for Predicting Rate of Biogas Production | Adamu ...

    African Journals Online (AJOL)

    Rate of biogas production using cow manure as substrate was monitored in two laboratory scale batch reactors (13 liter and 108 liter capacities). Two empirical models based on the Gompertz and the modified logistic equations were used to fit the experimental data based on non-linear regression analysis using Solver tool ...

  2. Optimum stocking rate for goat production on improved highland ...

    African Journals Online (AJOL)

    The effects of four stocking rates (SR; 7.5, 15, 30 and 45 goats ha-1) on goat performance and herbage productivity were examined on the perennial pastures. The experiment was applied by grazing 65 six-months old Chinese Yunling black goat wethers for two years. Significant year × SR interactions were observed on ...

  3. Mapping of cerebral metabolic rate of oxygen using dynamic susceptibility contrast and blood oxygen level dependent MR imaging in acute ischemic stroke

    Energy Technology Data Exchange (ETDEWEB)

    Gersing, Alexandra S.; Schwaiger, Benedikt J. [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); University of California, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Ankenbrank, Monika; Toth, Vivien; Bauer, Jan S.; Zimmer, Claus [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); Janssen, Insa [Technical University Munich, Department of Neurosurgery, Munich (Germany); Kooijman, Hendrik [Philips Healthcare, Hamburg (Germany); Wunderlich, Silke [Technical University Munich, Department of Neurology, Munich (Germany); Preibisch, Christine [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); Technical University Munich, Department of Neurology, Munich (Germany)

    2015-12-15

    MR-derived cerebral metabolic rate of oxygen utilization (CMRO{sub 2}) has been suggested to be analogous to PET-derived CMRO{sub 2} and therefore may be used for detection of viable tissue at risk for infarction. The purpose of this study was to evaluate MR-derived CMRO{sub 2} mapping in acute ischemic stroke in relation to established diffusion- and perfusion-weighted imaging. In 23 patients (mean age 63 ± 18.7 years, 11 women) with imaging findings for acute ischemic stroke, relative oxygen extraction fraction was calculated from quantitative transverse relaxation times (T2, T2*) and relative cerebral blood volume using a quantitative blood oxygenation level dependent (BOLD) approach in order to detect a local increase of deoxyhemoglobin. Relative CMRO{sub 2} (rCMRO{sub 2}) maps were calculated by multiplying relative oxygen extraction fraction (rOEF) by cerebral blood flow, derived from PWI. After co-registration, rCMRO{sub 2} maps were evaluated in comparison with apparent diffusion coefficient (ADC) and time-to-peak (TTP) maps. Mean rCMRO{sub 2} values in areas with diffusion-restriction or TTP/ADC mismatch were compared with rCMRO{sub 2} values in the contralateral tissue. In tissue with diffusion restriction, mean rCMRO{sub 2} values were significantly decreased compared to perfusion-impaired (17.9 [95 % confidence interval 10.3, 25.0] vs. 58.1 [95 % confidence interval 50.1, 70.3]; P < 0.001) and tissue in the contralateral hemisphere (68.2 [95 % confidence interval 61.4, 75.0]; P < 0.001). rCMRO{sub 2} in perfusion-impaired tissue showed no significant change compared to tissue in the contralateral hemisphere (58.1 [95 % confidence interval 50.1, 70.3] vs. 66.7 [95 % confidence interval 53.4, 73.4]; P = 0.34). MR-derived CMRO{sub 2} was decreased within diffusion-restricted tissue and stable within perfusion-impaired tissue, suggesting that this technique may be adequate to reveal different pathophysiological stages in acute stroke. (orig.)

  4. Multi-Use Solar Thermal System for Oxygen Production from Lunar Regolith [7227-570], Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop an innovative solar thermal system for oxygen production from lunar regolith. In this system solar radiation is collected by the concentrator...

  5. Effects of oxygen supply condition and specific biofilm interfacial area on phenol removal rate in a three-phase fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, A.; Meutia, A. A.; Osawa, M.; Arai, M.; Tsuneda, S. [Waseda Univ., Dept. of Chemical Engineering, Tokyo (Japan)

    2000-02-01

    A theoretical and experimental evaluation of the effects of superficial gas velocity, oxygen concentration in the gas phase, and specific biofilm interfacial area on the volumetric removal rate of phenol is described. The reaction rate was found to follow first order reaction kinetics with respect to oxygen, and zero-order reaction kinetics with respect to phenol. A semi-theoretical equation was developed which is capable of predicting the volumetric removal rate and is used to explain the overall removal rate of phenol. Biological reaction as the rate-controlling step and oxygen absorption are both explicable by this equation. 14 refs., 5 figs.

  6. Method for the determination of oxygen consumption rates and diffusion coefficients in multicellular spheroids

    OpenAIRE

    Mueller-Klieser, W.

    1984-01-01

    A method has been developed for the quantitative evaluation of oxygen tension (PO2) distributions in multicellular spheroids measured with O2-sensitive microelectrodes. The experimental data showed that multicellular tumor spheroids in stirred growth media were characterized by a diffusion-depleted zone surrounding the spheroids. This zone was elicited by an unstirred layer of medium next to the spheroid leading to a continuous decrease in the PO2 values from the bulk medium towards the spher...

  7. Lunar Metal Oxide Electrolysis with Oxygen and Photovoltaic Array Production Applications

    Science.gov (United States)

    Curreri, P. A.; Ethridge, E.; Hudson, S.; Sen, S.

    2006-01-01

    This paper presents the results of a Marshall Space Flight Center funded effort to conduct an experimental demonstration of the processing of simulated lunar resources by the molten oxide electrolysis (MOE) process to produce oxygen and metal from lunar resources to support human exploration of space. Oxygen extracted from lunar materials can be used for life support and propellant, and silicon and metallic elements produced can be used for in situ fabrication of thin-film solar cells for power production. The Moon is rich in mineral resources, but it is almost devoid of chemical reducing agents, therefore, molten oxide electrolysis, MOE, is chosen for extraction, since the electron is the most practical reducing agent. MOE was also chosen for following reasons. First, electrolytic processing offers uncommon versatility in its insensitivity to feedstock composition. Secondly, oxide melts boast the twin key attributes of highest solubilizing capacity for regolith and lowest volatility of any candidate electrolytes. The former is critical in ensuring high productivity since cell current is limited by reactant solubility, while the latter simplifies cell design by obviating the need for a gas-tight reactor to contain evaporation losses as would be the case with a gas or liquid phase fluoride reagent operating at such high temperatures. In the experiments reported here, melts containing iron oxide were electrolyzed in a low temperature supporting oxide electrolyte (developed by D. Sadoway, MIT). The production of oxygen and reduced iron were observed. Electrolysis was also performed on the supporting electrolyte with JSC-1 Lunar Simulant. The cell current for the supporting electrolyte alone is negligible while the current for the electrolyte with JSC-1 shows significant current and a peak at about -0.6 V indicating reductive reaction in the simulant.

  8. Sinoporphyrin sodium, a novel sensitizer, triggers mitochondrial-dependent apoptosis in ECA-109 cells via production of reactive oxygen species

    Directory of Open Access Journals (Sweden)

    Wang H

    2014-06-01

    induced by SDT was effectively remitted by ROS scavengers. DVDMS located mainly to the mitochondria of ECA-109 cells, which were seriously damaged after exposure to SDT. Release of cytochrome C, an increased rate of apoptosis, and activated apoptosis protein were detected in the SDT group. In addition, relatively severe cell damage was observed on scanning electron microscopy after treatment with DVDMS and SDT. Conclusion: These results suggest that DVDMS could be activated by ultrasound, and that DVDMS mediates SDT-induced mitochondrial-dependent apoptosis in ECA-109 cells via production of ROS. Keywords: sonodynamic therapy, sinoporphyrin sodium, reactive oxygen species, mitochondrial damage, apoptosis, ECA-109 cells

  9. THE PRODUCTION RATE OF SN Ia EVENTS IN GLOBULAR CLUSTERS

    International Nuclear Information System (INIS)

    Washabaugh, Pearce C.; Bregman, Joel N.

    2013-01-01

    In globular clusters, dynamical evolution produces luminous X-ray emitting binaries at a rate about 200 times greater than in the field. If globular clusters also produce SN Ia at a high rate, it would account for many of the SN Ia production in early-type galaxies and provide insight into their formation. Here we use archival Hubble Space Telescope (HST) images of nearby galaxies that have hosted an SN Ia to examine the rate at which globular clusters produce these events. The location of the SN Ia is registered on an HST image obtained before the event or after the supernova (SN) faded. Of the 36 nearby galaxies examined, 21 had sufficiently good data to search for globular cluster hosts. None of the 21 SNe have a definite globular cluster counterpart, although there are some ambiguous cases. This places an upper limit to the enhancement rate of SN Ia production in globular clusters of about 42 at the 95% confidence level, which is an order of magnitude lower than the enhancement rate for luminous X-ray binaries. Even if all of the ambiguous cases are considered as having a globular cluster counterpart, the upper bound for the enhancement rate is 82 at the 95% confidence level, still a factor of several below that needed to account for half of the SN Ia events. Barring unforeseen selection effects, we conclude that globular clusters are not responsible for producing a significant fraction of the SN Ia events in early-type galaxies.

  10. Efficiencies for production of atomic nitrogen and oxygen by relativistic proton impact in air

    Science.gov (United States)

    Porter, H. S.; Jackman, C. H.; Green, A. E. S.

    1976-01-01

    Relativistic electron and proton impact cross sections are obtained and represented by analytic forms which span the energy range from threshold to 1 GeV. For ionization processes, the Massey-Mohr continuum generalized oscillator strength surface is parameterized. Parameters are determined by simultaneous fitting to (1) empirical data, (2) the Bethe sum rule, and (3) doubly differential cross sections for ionization. Branching ratios for dissociation and predissociation from important states of N2 and O2 are determined. The efficiency for the production of atomic nitrogen and oxygen by protons with kinetic energy less than 1 GeV is determined using these branching ratio and cross section assignments.

  11. The role of biology in planetary evolution: cyanobacterial primary production in low-oxygen Proterozoic oceans.

    Science.gov (United States)

    Hamilton, Trinity L; Bryant, Donald A; Macalady, Jennifer L

    2016-02-01

    Understanding the role of biology in planetary evolution remains an outstanding challenge to geobiologists. Progress towards unravelling this puzzle for Earth is hindered by the scarcity of well-preserved rocks from the Archean (4.0 to 2.5 Gyr ago) and Proterozoic (2.5 to 0.5 Gyr ago) Eons. In addition, the microscopic life that dominated Earth's biota for most of its history left a poor fossil record, consisting primarily of lithified microbial mats, rare microbial body fossils and membrane-derived hydrocarbon molecules that are still challenging to interpret. However, it is clear from the sulfur isotope record and other geochemical proxies that the production of oxygen or oxidizing power radically changed Earth's surface and atmosphere during the Proterozoic Eon, pushing it away from the more reducing conditions prevalent during the Archean. In addition to ancient rocks, our reconstruction of Earth's redox evolution is informed by our knowledge of biogeochemical cycles catalysed by extant biota. The emergence of oxygenic photosynthesis in ancient cyanobacteria represents one of the most impressive microbial innovations in Earth's history, and oxygenic photosynthesis is the largest source of O2 in the atmosphere today. Thus the study of microbial metabolisms and evolution provides an important link between extant biota and the clues from the geologic record. Here, we consider the physiology of cyanobacteria (the only microorganisms capable of oxygenic photosynthesis), their co-occurrence with anoxygenic phototrophs in a variety of environments and their persistence in low-oxygen environments, including in water columns as well as mats, throughout much of Earth's history. We examine insights gained from both the rock record and cyanobacteria presently living in early Earth analogue ecosystems and synthesize current knowledge of these ancient microbial mediators in planetary redox evolution. Our analysis supports the hypothesis that anoxygenic photosynthesis

  12. Experimental Determination of the Cosmogenic Ar Production Rate From Ca

    Science.gov (United States)

    Niedermann, S.; Schäfer, J. M.; Wieler, R.; Naumann, R.

    2005-12-01

    Cosmogenic 38Ar is produced in terrestrial surface rocks by spallation of target nuclides, in particular K and Ca. Though the presence of cosmogenic Ar in Ca-rich minerals has been demonstrated earlier [1], is has proven difficult to establish its production rate. To circumvent problems connected to 36Ar production by 35Cl neutron capture and different production rates from K and Ca, we have analyzed the noble gases in seven pyroxene separates (px) from the Antarctic Dry Valleys which are essentially free of Cl and K. The px were obtained from dolerite rocks, for which 3He and 21Ne exposure ages from 1.5 to 6.5 Ma have been reported [2]. The noble gases were extracted in two or three heating steps at GFZ Potsdam, yielding 38Ar/36Ar ratios up to 0.2283 ± 0.0008 (air: 0.1880). Ca (3.7-11.2 wt. %) is expected to be the only relevant target element for Ar production in the five pure px (ratio of 1.5 ± 0.2, we obtain cosmogenic 38Ar concentrations between 130 and 530x106 atoms/g. The 38Ar production rate was calculated based on 21Ne exposure ages [2], corrected for elevated nuclide production in Antarctica due to prevailing low air pressure and for the revised 21Ne production rate from Si. We obtain values between 188 ± 17 and 243 +110/-24 atoms (g Ca)-1 a-1 at sea level and high (northern) latitudes for four out of the five pure px, while one yields a very high value of 348 ± 70 atoms (g Ca)-1 a-1. Values above 250 atoms (g Ca)-1 a-1 are also obtained from two less pure px containing 0.3 and 0.9% K and from one feldspar/quartz accumulate, indicating that the production rate from K may be higher than that from Ca. The weighted mean (excluding the outlier) of ~200 atoms (g Ca)-1 a-1 is in excellent agreement with Lal's [3] theoretical estimate. [1] Renne et al., EPSL 188 (2001) 435. [2] Schäfer et al., EPSL 167 (1999) 215. [3] Lal, EPSL 104 (1991) 424.

  13. Feed-derived volatile basic nitrogen increases reactive oxygen species production of blood leukocytes in lactating dairy cows.

    Science.gov (United States)

    Tsunoda, Ei; Gross, Josef J; Kawashima, Chiho; Bruckmaier, Rupert M; Kida, Katsuya; Miyamoto, Akio

    2017-01-01

    The present study investigated over 9 months the changes of fermentative quality of total mixed rations (TMR) containing grass silage (GS) as a major component, associated with changes in the volatile basic nitrogen (VBN) levels in an experimental dairy farm. Effects of VBN levels in TMR on metabolic parameters, reactive oxygen species (ROS) production by blood polymorphonuclear leukocytes (PMNs) and conception rates for dairy cows were analyzed. According to VBN levels in TMR during survey periods, three distinct phases were identified; phase A with low VBN; phase B with high VBN; and phase C with mid-VBN. Metabolic parameters in blood were all within normal range. However, during phases B and C, nitrogen metabolic indices such as blood urea nitrogen and milk urea nitrogen showed higher levels compared to those in phase A, and a simultaneous increase in ROS production by blood PMNs and the load on hepatic function in metabolic parameters was observed in the cows with a lower conception rate. This suggests that feeding TMR with elevated VBN levels due to poor fermented GS results in stimulation of ROS production by PMNs by ammonia, and negatively affects metabolism and reproductive performance in lactating dairy cow. © 2016 Japanese Society of Animal Science.

  14. Mixomics analysis of Bacillus subtilis: effect of oxygen availability on riboflavin production.

    Science.gov (United States)

    Hu, Junlang; Lei, Pan; Mohsin, Ali; Liu, Xiaoyun; Huang, Mingzhi; Li, Liang; Hu, Jianhua; Hang, Haifeng; Zhuang, Yingping; Guo, Meijin

    2017-09-12

    Riboflavin, an intermediate of primary metabolism, is one kind of important food additive with high economic value. The microbial cell factory Bacillus subtilis has already been proven to possess significant importance for the food industry and have become one of the most widely used riboflavin-producing strains. In the practical fermentation processes, a sharp decrease in riboflavin production is encountered along with a decrease in the dissolved oxygen (DO) tension. Influence of this oxygen availability on riboflavin biosynthesis through carbon central metabolic pathways in B. subtilis is unknown so far. Therefore the unveiled effective metabolic pathways were still an unaccomplished task till present research work. In this paper, the microscopic regulation mechanisms of B. subtilis grown under different dissolved oxygen tensions were studied by integrating 13 C metabolic flux analysis, metabolomics and transcriptomics. It was revealed that the glucose metabolic flux through pentose phosphate (PP) pathway was lower as being confirmed by smaller pool sizes of metabolites in PP pathway and lower expression amount of ykgB at transcriptional level. The latter encodes 6-phosphogluconolactonase (6-PGL) under low DO tension. In response to low DO tension in broth, the glucose metabolic flux through Embden-Meyerhof-Parnas (EMP) pathway was higher and the gene, alsS, encoding for acetolactate synthase was significantly activated that may result due to lower ATP concentration and higher NADH/NAD + ratio. Moreover, ResE, a membrane-anchored protein that is capable of oxygen regulated phosphorylase activity, and ResD, a regulatory protein that can be phosphorylated and dephosphorylated by ResE, were considered as DO tension sensor and transcriptional regulator respectively. This study shows that integration of transcriptomics, 13 C metabolic flux analysis and metabolomics analysis provides a comprehensive understanding of biosynthesized riboflavin's regulatory mechanisms in

  15. Automated Production of High Rep Rate Foam Targets

    Science.gov (United States)

    Hall, F.; Spindloe, C.; Haddock, D.; Tolley, M.; Nazarov, W.

    2016-04-01

    Manufacturing low density targets in the numbers needed for high rep rate experiments is highly challenging. This report summarises advances from manual production to semiautomated and the improvements that follow both in terms of production time and target uniformity. The production process is described and shown to be improved by the integration of an xyz robot with dispensing capabilities. Results are obtained from manual and semiautomated production runs and compared. The variance in the foam thickness is reduced significantly which should decrease experimental variation due to target parameters and could allow for whole batches to be characterised by the measurement of a few samples. The work applies to both foil backed and free standing foam targets.

  16. Modeling Electric Discharges with Entropy Production Rate Principles

    Directory of Open Access Journals (Sweden)

    Thomas Christen

    2009-12-01

    Full Text Available Under which circumstances are variational principles based on entropy production rate useful tools for modeling steady states of electric (gas discharge systems far from equilibrium? It is first shown how various different approaches, as Steenbeck’s minimum voltage and Prigogine’s minimum entropy production rate principles are related to the maximum entropy production rate principle (MEPP. Secondly, three typical examples are discussed, which provide a certain insight in the structure of the models that are candidates for MEPP application. It is then thirdly argued that MEPP, although not being an exact physical law, may provide reasonable model parameter estimates, provided the constraints contain the relevant (nonlinear physical effects and the parameters to be determined are related to disregarded weak constraints that affect mainly global entropy production. Finally, it is additionally conjectured that a further reason for the success of MEPP in certain far from equilibrium systems might be based on a hidden linearity of the underlying kinetic equation(s.

  17. Modelling the bioconversion of cellulose into microbial products: rate limitations

    Energy Technology Data Exchange (ETDEWEB)

    Asenjo, J A

    1984-12-01

    The direct bioconversion of cellulose into microbial products carried out as a simultaneous saccharification and fermentation has a strong effect on the rates of cellulose degradation because cellobiose and glucose inhibition of the reaction are circumvented. A general mathematical model of the kinetics of this bioconversion has been developed. Its use in representing aerobic systems and in the analysis of the kinetic limitations has been investigated. Simulations have been carried out to find the rate limiting steps in slow fermentations and in rapid ones as determined by the specific rate of product formation. The requirements for solubilising and depolymerising enzyme activities (cellulase and cellobiase) in these systems has been determined. The activity that have been obtained for fungal cellulases are adequate for the kinetic requirements of the fastest fermentative strains. The results also show that for simultaneous bioconversions where strong cellobiose and glucose inhibition is overcome, no additional cellobiase is necessary to increase the rate of product formation. These results are useful for the selection of cellolytic micro-organisms and in the determination of enzymes to be cloned in recombinant strains. 17 references.

  18. High production rate of IBAD-MgO buffered substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizumi, M., E-mail: myoshizumi@istec.or.j [Superconductivity Research Laboratory, ISTEC, Shinonome 1-10-13, Koto-ku, Tokyo 135-0062 (Japan); Miyata, S.; Ibi, A.; Fukushima, H.; Yamada, Y.; Izumi, T.; Shiohara, Y. [Superconductivity Research Laboratory, ISTEC, Shinonome 1-10-13, Koto-ku, Tokyo 135-0062 (Japan)

    2009-10-15

    The conventional IBAD (Ion Beam Assisted Deposition) process using fluorite materials yields low production rates, resulting in high production cost, which reduces the motivation for practical application in spite of its high quality. The IBAD process using rock salt materials, e.g. MgO, is well known as a strong candidate of practical application due to its potential of high production rate and high in-plane grain alignment. In this work, the IBAD-MgO process was investigated for a newly developed architecture of PLD (Pulsed Laser Deposition)-CeO{sub 2}/sputter-LMO (LaMnO{sub 3})/IBAD-MgO/sputter-GZO (Gd{sub 2}Zr{sub 2}O{sub 7})/Hastelloy{sup TM} to make long buffered metal tapes with high properties and a high production rate. The 50 m-long IBAD-MgO substrates with about 4 deg. of DELTAphiCeO{sub 2} in an XRD phi scan could be fabricated repeatedly. A GdBCO (GdBa{sub 2}Cu{sub 3}O{sub x}) layer deposited on the buffered substrate showed the minimum I{sub c} value of 325 A/cm-w in a 41 m-long tape. Almost of the tape showed 500-600 A/cm-w of I{sub c} value. The deposition time for the IBAD-MgO layer was 60 s which was about 2 orders of magnitude shorter than the conventional IBAD process. The production rate of 24 m/h was realized at the IBAD-MgO process to fabricate the GdBCO coated conductor with high J{sub c} and I{sub c} properties.

  19. Reaction rate and energy-loss rate for photopair production by relativistic nuclei

    Science.gov (United States)

    Chodorowski, Michal J.; Zdziarski, Andrzej A.; Sikora, Marek

    1992-01-01

    The process of e(+/-) pair production by relativistic nuclei on ambient photons is considered. The process is important for cosmic-ray nuclei in interstellar and intergalactic space as well as in galactic and extragalactic compact objects. The rate of this process is given by an integral of the cross section over the photon angular and energy distribution. In the case of isotropic photons, the angular integration is performed to provide an expression for the rate at given photon energy in the nucleus rest frame. The total rate then becomes a single integral of that rate over the photon energy distribution. Formulas are also given for the fractional energy loss of a relativistic nucleus colliding with a photon of a given energy in the rest frame. The nucleus energy-loss rate is integrated over the photon angular distribution in the case of isotropic photons, and simple fits are provided.

  20. Live Candida albicans Suppresses Production of Reactive Oxygen Species in Phagocytes▿ †

    Science.gov (United States)

    Wellington, Melanie; Dolan, Kristy; Krysan, Damian J.

    2009-01-01

    Production of reactive oxygen species (ROS) is an important aspect of phagocyte-mediated host responses. Since phagocytes play a crucial role in the host response to Candida albicans, we examined the ability of Candida to modulate phagocyte ROS production. ROS production was measured in the murine macrophage cell line J774 and in primary phagocytes using luminol-enhanced chemiluminescence. J774 cells, murine polymorphonuclear leukocytes (PMN), human monocytes, and human PMN treated with live C. albicans produced significantly less ROS than phagocytes treated with heat-killed C. albicans. Live C. albicans also suppressed ROS production in murine bone marrow-derived macrophages from C57BL/6 mice, but not from BALB/c mice. Live C. albicans also suppressed ROS in response to external stimuli. C. albicans and Candida glabrata suppressed ROS production by phagocytes, whereas Saccharomyces cerevisiae stimulated ROS production. The cell wall is the initial point of contact between Candida and phagocytes, but isolated cell walls from both heat-killed and live C. albicans stimulated ROS production. Heat-killed C. albicans has increased surface exposure of 1,3-β-glucan, a cell wall component that can stimulate phagocytes. To determine whether surface 1,3-β-glucan exposure accounted for the difference in ROS production, live C. albicans cells were treated with a sublethal dose of caspofungin to increase surface 1,3-β-glucan exposure. Caspofungin-treated C. albicans was fully able to suppress ROS production, indicating that suppression of ROS overrides stimulatory signals from 1,3-β-glucan. These studies indicate that live C. albicans actively suppresses ROS production in phagocytes in vitro, which may represent an important immune evasion mechanism. PMID:18981256

  1. 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...

  2. Performance Testing of Molten Regolith Electrolysis with Transfer of Molten Material for the Production of Oxygen and Metals on the Moon

    Science.gov (United States)

    Sibille, Laurent; Sadoway, Donald; Tripathy, Prabhat; Standish, Evan; Sirk, Aislinn; Melendez, Orlando; Stefanescu, Doru

    2010-01-01

    Previously, we have demonstrated the production of oxygen by electrolysis of molten regolith simulants at temperatures near 1600 C. Using an inert anode and suitable cathode, direct electrolysis (no supporting electrolyte) of the molten silicate is carried out, resulting in the production of molten metallic products at the cathode and oxygen gas at the anode. Initial direct measurements of current efficiency have confirmed that the process offer potential advantages of high oxygen production rates in a smaller footprint facility landed on the moon, with a minimum of consumables brought from Earth. We now report the results of a scale-up effort toward the goal of achieving production rates equivalent to 1 metric ton O2/year, a benchmark established for the support of a lunar base. We previously reported on the electrochemical behavior of the molten electrolyte as dependent on anode material, sweep rate and electrolyte composition in batches of 20-200g and at currents of less than 0.5 A. In this paper, we present the results of experiments performed at currents up to 10 Amperes) and in larger volumes of regolith simulant (500 g - 1 kg) for longer durations of electrolysis. The technical development of critical design components is described, including: inert anodes capable of passing continuous currents of several Amperes, container materials selection, direct gas analysis capability to determine the gas components co-evolving with oxygen. To allow a continuous process, a system has been designed and tested to enable the withdrawal of cathodically-reduced molten metals and spent molten oxide electrolyte. The performance of the withdrawal system is presented and critiqued. The design of the electrolytic cell and the configuration of the furnace were supported by modeling the thermal environment of the system in an effort to realize a balance between external heating and internal joule heating. We will discuss the impact these simulations and experimental findings have

  3. Gas production and decline rates in the province of Alberta

    International Nuclear Information System (INIS)

    Samson, L.A.

    1999-01-01

    A detailed study was conducted to evaluate the gas production decline rates in Alberta. The study examined the producing gas wells that were place in production between 1990 and 1997. Three major assumptions were used to determine the number of wells necessary to meet future market demand. These were: (1) reserves have been declining at greater rates in the past several years. The current rate of decline is 12 per cent, (2) new reserves added in future will produce at 5.1 E6M3 per year, and (3) the decline rates for new gas wells will be 27 per cent in the first year, 16 per cent in the second year, 12 per cent in the third year and thereafter. With this information, the Alberta Energy and Utilities Board estimates that the annual total deliveries of gas from Alberta in the year 2002 will be 177.4 E9M3 compared to 127 E9M3 in 1997. In order to meet this supply, drilling activity for successful gas wells will have to double the 1997 rate because it is predicted that more than 6400 new wells will be needed per year to meet future demand. 2 refs., 2 tabs., 20 figs

  4. Influence of oxygen flow rate on metal-insulator transition of vanadium oxide thin films grown by RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xu; Liu, Xinkun; Li, Haizhu; Huang, Mingju [Henan University, Key Lab of Informational Opto-Electronical Materials and Apparatus, School of Physics and Electronics, Kaifeng (China); Zhang, Angran [South China Normal University, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, Guangzhou (China)

    2017-03-15

    High-quality vanadium oxide (VO{sub 2}) films have been fabricated on Si (111) substrates by radio frequency (RF) magnetron sputtering deposition method. The sheet resistance of VO{sub 2} has a significant change (close to 5 orders of magnitude) in the process of the metal-insulator phase transition (MIT). The field emission-scanning electron microscope (FE-SEM) results show the grain size of VO{sub 2} thin films is larger with the increase of oxygen flow. The X-ray diffraction (XRD) results indicate the thin films fabricated at different oxygen flow rates grow along the (011) crystalline orientation. As the oxygen flow rate increases from 3 sccm to 6 sccm, the phase transition temperature of the films reduces from 341 to 320 K, the width of the thermal hysteresis loop decreases from 32 to 9 K. The thin films fabricated in the condition of 5 sccm have a high temperature coefficient of resistance (TCR) -3.455%/K with a small resistivity of 2.795 ρ/Ω cm. (orig.)

  5. The effect of oxygen content during an initial sustained inflation on heart rate in asphyxiated near-term lambs.

    Science.gov (United States)

    Sobotka, K S; Ong, T; Polglase, G R; Crossley, K J; Moss, T J M; Hooper, S B

    2015-07-01

    At birth, an initial sustained inflation (SI) uniformly aerates the lungs, increases arterial oxygenation and rapidly improves circulatory recovery in asphyxiated newborns. We hypothesised that lung aeration, in the absence of an increase in arterial oxygenation, can increase heart rate (HR) in asphyxiated near-term lambs. Lambs were delivered and instrumented at 139±2 days of gestation. Asphyxia was induced by umbilical cord clamping and then delaying the onset of ventilation until mean carotid arterial pressures (CAPs) had decreased <20 mm Hg. Lambs then received a single 30-s SI using nitrogen (N2; n=6), 5% oxygen (O2; n=6), 21% O2 (n=6) or 100% O2 (n=6) followed by ventilation in air for 30 min. HR, CAP and pulmonary blood flow (PBF) were continuously recorded. HR and PBF increased more quickly in lambs resuscitated with 100% and 21% O2 than with 5% O2 or N2. HR and PBF recovery in the 5% O2 group was delayed relative to all other oxygen SI groups. HR in 5%, 21% and 100% O2 groups reached 100 bpm before the SI was complete. HR and PBF in the N2 group did not increase until 10 s after the SI was completed and ventilation was initiated with air. CAP tended to increase quicker in all O2 groups than in N2 group. Oxygen content during an SI is important for circulatory recovery in asphyxiated lambs. This increase in HR is likely driven by the increase in PBF and venous return to the heart. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  6. 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.

  7. Elevated global cerebral blood flow, oxygen extraction fraction and unchanged metabolic rate of oxygen in young adults with end-stage renal disease: an MRI study

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Gang; Lou, Yaxian; Pan, Zhiying; Liu, Ya [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China); Nanjing University of Aeronautics and Astronautics, College of Aivil Aviation, Nanjing, Jiangsu (China); Wen, Jiqiu; Li, Xue; Zhang, Zhe [Medical School of Nanjing University, National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing, Jiangsu (China); Lu, Hanzhang [University of Texas Southwestern Medical Center, Advanced Imaging Research Center, Dallas, TX (United States); Liu, Wei [Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, Guangdong (China); Liu, Hui [Siemens MR NEA Collaboration, Siemens Ltd., Shanghai (China); Chen, Huijuan; Kong, Xiang; Luo, Song; Jiang, Xiaolu; Zhang, Zongjun; Zhang, Long Jiang; Lu, Guang Ming [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China)

    2016-06-15

    To noninvasively assess global cerebral blood flow (CBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO{sub 2}) in young adults with end-stage renal disease (ESRD). Thirty-six patients and 38 healthy volunteers were included and took part in MR examinations, blood and neuropsychological tests. CBF and OEF were measured by phase-contrast and T2-relaxation-under-spin-tagging MRI techniques, respectively. CMRO{sub 2} was computed from CBF, OEF and hematocrit according to Fick's principle. Correlations were performed between MR measurements, blood biochemistry measurements and neuropsychological test scores. Compared with controls, ESRD patients had elevated CBF (72.9 ± 12.5 vs. 63.8 ± 8.5 ml min{sup -1} 100 g{sup -1}, P < 0.001), elevated OEF (47.2 ± 10.2 vs. 35.8 ± 5.4 %, P < 0.001), but unaffected CMRO{sub 2} (199.5 ± 36.4 vs. 193.8 ± 28.6 μmol O{sub 2} min{sup -1} 100 g{sup -1}, P = 0.879). Hematocrit negatively correlated with CBF (r = -0.640, P < 0.001) and OEF (r = -0.701, P < 0.001), but not with CMRO{sub 2}. Altered neuropsychological test scores of ESRD patients were associated with OEF and CBF, but not with CMRO{sub 2}. There were weak relationships between eGFR and hematocrit (r = 0.308, P = 0.068) or CBF (r = 0.318, P = 0.059). Our findings suggested that anaemic young adults with ESRD may afford higher CBF and OEF to maintain a normal CMRO{sub 2}. Despite this compensatory process, however, cognitive function was still impaired and its severity was correlated with their CBF and OEF abnormality. (orig.)

  8. Elevated global cerebral blood flow, oxygen extraction fraction and unchanged metabolic rate of oxygen in young adults with end-stage renal disease: an MRI study

    International Nuclear Information System (INIS)

    Zheng, Gang; Lou, Yaxian; Pan, Zhiying; Liu, Ya; Wen, Jiqiu; Li, Xue; Zhang, Zhe; Lu, Hanzhang; Liu, Wei; Liu, Hui; Chen, Huijuan; Kong, Xiang; Luo, Song; Jiang, Xiaolu; Zhang, Zongjun; Zhang, Long Jiang; Lu, Guang Ming

    2016-01-01

    To noninvasively assess global cerebral blood flow (CBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO 2 ) in young adults with end-stage renal disease (ESRD). Thirty-six patients and 38 healthy volunteers were included and took part in MR examinations, blood and neuropsychological tests. CBF and OEF were measured by phase-contrast and T2-relaxation-under-spin-tagging MRI techniques, respectively. CMRO 2 was computed from CBF, OEF and hematocrit according to Fick's principle. Correlations were performed between MR measurements, blood biochemistry measurements and neuropsychological test scores. Compared with controls, ESRD patients had elevated CBF (72.9 ± 12.5 vs. 63.8 ± 8.5 ml min -1 100 g -1 , P < 0.001), elevated OEF (47.2 ± 10.2 vs. 35.8 ± 5.4 %, P < 0.001), but unaffected CMRO 2 (199.5 ± 36.4 vs. 193.8 ± 28.6 μmol O 2 min -1 100 g -1 , P = 0.879). Hematocrit negatively correlated with CBF (r = -0.640, P < 0.001) and OEF (r = -0.701, P < 0.001), but not with CMRO 2 . Altered neuropsychological test scores of ESRD patients were associated with OEF and CBF, but not with CMRO 2 . There were weak relationships between eGFR and hematocrit (r = 0.308, P = 0.068) or CBF (r = 0.318, P = 0.059). Our findings suggested that anaemic young adults with ESRD may afford higher CBF and OEF to maintain a normal CMRO 2 . Despite this compensatory process, however, cognitive function was still impaired and its severity was correlated with their CBF and OEF abnormality. (orig.)

  9. The effect of seeding with bacteria on biogas production rate

    Energy Technology Data Exchange (ETDEWEB)

    Dangoggo, S.M. [Usmanu Danfodiyo University, Sokoto (Nigeria). Dept. of Chemistry; Aliyu, M.; Atiku, A.T. [Usmanu Danfodiyo University, Sokoto (Nigeria). Energy Research Centre

    1996-09-01

    Biogas as a clean and cheap fuel is studied with the aim of determining the effect of seeding with bacteria on its production rate using four different substrates. The seeding with four different digesters was carried out with 5g of digested cowdung sludge obtained from a working digester. Results indicate that of all the substrates used for the studies, ipomea asarifobia produced the highest amount of biogas over a period of 40 days. (Author)

  10. Enhanced photon production rate on the light-cone

    International Nuclear Information System (INIS)

    Aurenche, P.; Grenoble-1 Univ., 74 - Annecy; Gelis, F.; Kobes, R.; Petitgirard, E.

    1996-01-01

    Recent studies of the high temperature soft photon production rate on the light cone using Braaten-Pisarski resummation techniques have found collinear divergences present. It is shown that there exist a class of terms outside the Braaten-Pisarski framework which, although also divergent, dominate over these previously considered terms. The divergences in these new terms may be alleviated by application of a recently developed resummation scheme for processes sensitive to the light-cone. (author)

  11. Overexpression of Genes Encoding Glycolytic Enzymes in Corynebacterium glutamicum Enhances Glucose Metabolism and Alanine Production under Oxygen Deprivation Conditions

    Science.gov (United States)

    Yamamoto, Shogo; Gunji, Wataru; Suzuki, Hiroaki; Toda, Hiroshi; Suda, Masako; Jojima, Toru; Inui, Masayuki

    2012-01-01

    We previously reported that Corynebacterium glutamicum strain ΔldhAΔppc+alaD+gapA, overexpressing glyceraldehyde-3-phosphate dehydrogenase-encoding gapA, shows significantly improved glucose consumption and alanine formation under oxygen deprivation conditions (T. Jojima, M. Fujii, E. Mori, M. Inui, and H. Yukawa, Appl. Microbiol. Biotechnol. 87:159–165, 2010). In this study, we employ stepwise overexpression and chromosomal integration of a total of four genes encoding glycolytic enzymes (herein referred to as glycolytic genes) to demonstrate further successive improvements in C. glutamicum glucose metabolism under oxygen deprivation. In addition to gapA, overexpressing pyruvate kinase-encoding pyk and phosphofructokinase-encoding pfk enabled strain GLY2/pCRD500 to realize respective 13% and 20% improved rates of glucose consumption and alanine formation compared to GLY1/pCRD500. Subsequent overexpression of glucose-6-phosphate isomerase-encoding gpi in strain GLY3/pCRD500 further improved its glucose metabolism. Notably, both alanine productivity and yield increased after each overexpression step. After 48 h of incubation, GLY3/pCRD500 produced 2,430 mM alanine at a yield of 91.8%. This was 6.4-fold higher productivity than that of the wild-type strain. Intracellular metabolite analysis showed that gapA overexpression led to a decreased concentration of metabolites upstream of glyceraldehyde-3-phosphate dehydrogenase, suggesting that the overexpression resolved a bottleneck in glycolysis. Changing ratios of the extracellular metabolites by overexpression of glycolytic genes resulted in reduction of the intracellular NADH/NAD+ ratio, which also plays an important role on the improvement of glucose consumption. Enhanced alanine dehydrogenase activity using a high-copy-number plasmid further accelerated the overall alanine productivity. Increase in glycolytic enzyme activities is a promising approach to make drastic progress in growth-arrested bioprocesses. PMID

  12. High-rate fermentative hydrogen production from beverage wastewater

    International Nuclear Information System (INIS)

    Sivagurunathan, Periyasamy; Sen, Biswarup; Lin, Chiu-Yue

    2015-01-01

    Highlights: • Hybrid immobilized-bacterial cells show stable operation over 175 days. • Low HRT of 1.5 h shows peak hydrogen production rate of 55 L/L-d. • Electricity generation is 9024 kW-d from 55 L/L-d hydrogen using beverage wastewater. • Granular sludge formed only at 2–3 h HRT with presence of Selenomonas sp. - Abstract: Hydrogen production from beverage industry wastewater (20 g/L hexose equivalent ) using an immobilized cell reactor with a continuous mode of operation was studied at various hydraulic retention times (HRT, 8–1.5 h). Maximum hydrogen production rate (HPR) of 55 L/L-d was obtained at HRT 1.5 h (an organic loading of 320 g/L-d hexose equivalent ). This HPR value is much higher than those of other industrial wastewaters employed in fermentative hydrogen production. The cell biomass concentration peaked at 3 h HRT with a volatile suspended solids (VSS) concentration of 6.31 g/L (with presence of self-flocculating Selenomonas sp.), but it dropped to 3.54 gVSS/L at 1.5 h HRT. With the shortening of HRT, lactate concentration increased but the concentration of the dominant metabolite butyrate did not vary significantly. The Clostridium species dynamics was not significantly affected, but total microbial community structure changed with respect to HRT variation as evident from PCR–DGGE analyses. Analysis of energy production rate suggests that beverage wastewater is a high energy yielding feedstock, and can replace 24% of electricity consumption in a model beverage industry

  13. The production of carbon nanofibers and thin films on palladium catalysts from ethylene oxygen mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Jonathan [Los Alamos National Laboratory; Doorn, Stephen [Los Alamos National Laboratory; Atwater, Mark [UNM MECH.ENG.; Leseman, Zayd [UNM MECH.ENG.; Luhrs, Claudia C [UNM ENG.MECH; Diez, Yolanda F [SPAIN; Diaz, Angel M [SPAIN

    2009-01-01

    The characteristics of carbonaceous materials deposited in fuel rich ethylene-oxygen mixtures on three types of palladium: foil, sputtered film, and nanopowder, are reported. It was found that the form of palladium has a dramatic influence on the morphology of the deposited carbon. In particular, on sputtered film and powder, tight 'weaves' of sub-micron filaments formed quickly. In contrast, on foils under identical conditions, the dominant morphology is carbon thin films with basal planes oriented parallel to the substrate surface. Temperature, gas flow rate, reactant flow ratio (C2H4:02), and residence time (position) were found to influence both growth rate and type for all three forms of Pd. X-ray diffraction, high-resolution transmission electron microscopy, temperature-programmed oxidation, and Raman spectroscopy were used to assess the crystallinity of the as-deposited carbon, and it was determined that transmission electron microscopy and x-ray diffraction were the most reliable methods for determining crystallinity. The dependence of growth on reactor position, and the fact that no growth was observed in the absence of oxygen support the postulate that the carbon deposition proceeds by combustion generated radical species.

  14. Biphasic effect of oxygen radicals on prostaglandin production by rat mesangial cells

    International Nuclear Information System (INIS)

    Adler, S.; Stahl, R.A.K.; Baker, P.J.; Chen, Y.P.; Pritzl, P.M.; Couser, W.G.

    1987-01-01

    Cultured rat mesangial cells were exposed to a reactive oxygen species (ROS) generating system (xanthine plus xanthine oxidase) to explore the effect of ROS on their metabolism of arachidonic acid (AA). Cell viability, as assessed by 51 Cr release, was not affected by the concentrations of xanthine plus xanthine oxidase used. Prostaglandin E 2 (PGE 2 ) production following exposure to increasing quantities of xanthine plus xanthine oxidase was significantly decreased when cells were stimulated with the calcium ionophore A23187 or AA. Maximum suppression of production was seen within 10 min of ROS exposure. Thromboxane B 2 production was similarly decreased. This effect was reversed by addition of catalase to the ROS generating system but not by superoxide dismutase or mannitol, which suggested that H 2 O 2 was the responsible metabolite. High levels of H 2 O 2 suppressed PGE 2 production. Lower levels of H 2 O 2 resulted in significant stimulation of base-line PGE 2 production. Analysis of release of 3 H]AA-labeled metabolites from A23187-stimulated cells showed no effect of H 2 O 2 on phospholipase activity. Thus ROS can stimulate or inhibitor AA metabolism in the glomerular mesangium, which may have important effects on glomerular hemodynamics during glomerular injury

  15. Oxygen consumption rates in hovering hummingbirds reflect substrate-dependent differences in P/O ratios: carbohydrate as a 'premium fuel'.

    Science.gov (United States)

    Welch, Kenneth C; Altshuler, Douglas L; Suarez, Raul K

    2007-06-01

    The stoichiometric relationship of ATP production to oxygen consumption, i.e. the P/O ratio, varies depending on the nature of the metabolic substrate used. The latest estimates reveal a P/O ratio approximately 15% higher when glucose is oxidized compared with fatty acid oxidation. Because the energy required to produce aerodynamic lift for hovering is independent of the metabolic fuel oxidized, we hypothesized that the rate of oxygen consumption, VO2, should decline as the respiratory quotient, RQ (VCO2/VO2), increases from 0.71 to 1.0 as hummingbirds transition from a fasted to a fed state. Here, we show that hovering VO2 values in rufous (Selasphorus rufus) and Anna's hummingbirds (Calypte anna) are significantly greater when fats are metabolized (RQ=0.71) than when carbohydrates are used (RQ=1.0). Because hummingbirds gained mass during our experiments, making mass a confounding variable, we estimated VO2 per unit mechanical power output. Expressed in this way, the difference in VO2 when hummingbirds display an RQ=0.71 (fasted) and an RQ=1.0 (fed) is between 16 and 18%, depending on whether zero or perfect elastic energy storage is assumed. These values closely match theoretical expectations, indicating that a combination of mechanical power estimates and ;indirect calorimetry', i.e. the measurement of rates of gas exchange, enables precise estimates of ATP turnover and metabolic flux rates in vivo. The requirement for less oxygen when oxidizing carbohydrate suggests that carbohydrate oxidation may facilitate hovering flight in hummingbirds at high altitude.

  16. Rate and Product Studies of Solvolyses of Benzyl Fluoroformate

    Directory of Open Access Journals (Sweden)

    Dennis N. Kevill

    2006-07-01

    Full Text Available The specific rates of solvolysis of benzyl fluoroformate have been measured inseveral hydroxylic solvents at 25.0 °C. For methanolysis, the solvent deuterium isotopeeffect and activation parameters were determined and activation parameters were alsodetermined for solvolyses in ethanol and 80% ethanol. For several of the binary hydroxylicsolvents, measurement of product ratios allowed selectivity values to be determined. Anextended Grunwald–Winstein treatment of the data led to sensitivities to changes in solventnucleophilicity and ionizing power. Comparison with previously determined specific ratesfor solvolysis of the chloroformate gave fluorine/chlorine rate ratios greater than unity. Allof the determinations made were consistent with an addition–elimination (association–dissociation mechanism, with addition rate-determining.

  17. Success rates for product development strategies in new drug development.

    Science.gov (United States)

    Dahlin, E; Nelson, G M; Haynes, M; Sargeant, F

    2016-04-01

    While research has examined the likelihood that drugs progress across phases of clinical trials, no research to date has examined the types of product development strategies that are the most likely to be successful in clinical trials. This research seeks to identify the strategies that are most likely to reach the market-those generated using a novel product development strategy or strategies that combine a company's expertise with both drugs and indications, which we call combined experience strategies. We evaluate the success of product development strategies in the drug development process for a sample of 2562 clinical trials completed by 406 US pharmaceutical companies. To identify product development strategies, we coded each clinical trial according to whether it consisted of an indication or a drug that was new to the firm. Accordingly, a clinical trial that consists of both an indication and a drug that were both new to the firm represents a novel product development strategy; indication experience is a product development strategy that consists of an indication that a firm had tested previously in a clinical trial, but with a drug that was new to the firm; drug experience is a product development strategy that consists of a drug that the firm had prior experience testing in clinical trials, but with an indication that was new to the firm; combined experience consists of both a drug and an indication that the firm had experience testing in clinical trials. Success rates for product development strategies across clinical phases were calculated for the clinical trials in our sample. Combined experience strategies had the highest success rate. More than three and a half percent (0·036) of the trials that combined experience with drugs and indications eventually reached the market. The next most successful strategy is drug experience (0·025) with novel strategies trailing closely (0·024). Indication experience strategies are the least successful (0·008

  18. Cadmium accumulation in and tolerance of rice (Oryza sativa L.) varieties with different rates of radial oxygen loss

    International Nuclear Information System (INIS)

    Wang, M.Y.; Chen, A.K.; Wong, M.H.; Qiu, R.L.; Cheng, H.; Ye, Z.H.

    2011-01-01

    Cadmium (Cd) uptake and tolerance were investigated among 20 rice cultivars based on a field experiment (1.2 mg Cd kg -1 in soil) and a soil pot trial (control, 100 mg Cd kg -1 ), and rates of radial oxygen loss (ROL) were measured under a deoxygenated solution. Significant differences were found among the cultivars in: (1) brown rice Cd concentrations (0.11-0.29 mg kg -1 ) in a field soil, (2) grain Cd tolerance (34-113%) and concentrations (2.1-6.5 mg kg -1 ) in a pot trial, and (3) rates of ROL (15-31 mmol O 2 kg -1 root d.w. h -1 ). Target hazard quotients were calculated for the field experiment to assess potential Cd risk. Significant negative relationships were found between rates of ROL and concentrations of Cd in brown rice or straw under field and greenhouse conditions, indicating that rice cultivars with higher rates of ROL had higher capacities for limiting the transfer of Cd to rice and straw. - Highlights: → There are significant differences in brown rice Cd concentrations and rates of ROL among the rice cultivars. → The rates of ROL are significantly correlated with concentrations of Cd in brown rice. → Rice cultivars with higher rates of ROL have higher capacities for limiting the transfer of Cd to rice and straw. - Rice cultivars with high rates of ROL tended to accumulate low Cd in grains.

  19. Flow Rate Through Pigtail Catheter Used for Left Heart Decompression in an Artificial Model of Extracorporeal Membrane Oxygenation Circuit.

    Science.gov (United States)

    Kim, Won Ho; Hong, Tae Hee; Byun, Joung Hun; Kim, Jong Woo; Kim, Sung Hwan; Moon, Sung Ho; Park, Hyun Oh; Choi, Jun Young; Yang, Jun Ho; Jang, In Seok; Lee, Chung Eun; Yun, Jeong Hee

    In refractory cardiogenic shock, veno-arterial extracorporeal membrane oxygenation (ECMO) can be initiated. Although left heart decompression can be accomplished by insertion of a left atrial (LA) or left ventricular (LV) cannula using a percutaneous pigtail catheter, the venting flow rate according to catheter size and ECMO flow rate is unknown. We developed an artificial ECMO circuit. One liter saline bag with its pressure set to 20 mm Hg was connected to ECMO to mimic LV failure. A pigtail catheter was inserted into the 1 L saline bag to simulate LV unloading. For each pigtail catheter size (5-8 Fr) and ECMO flow rate (2.0-4.0 L/min), the moving distance of an air bubble that was injected through a three-way stopcock was measured in the arterial pressure line between the pigtail catheter and ECMO inflow limb. The flow rate was then calculated. We obtained the following equation to estimate the pigtail catheter flow rate.Pigtail vent catheter flow rate (ml/min) = 8×ECMOflow rate(L /min)+9×pigtail catheter size(Fr)- 57This equation would aid in designing of a further study to determine optimal venting flow rate. To achieve optimal venting flow, our equation would enable selection of an adequate catheter size.

  20. Rate constants for the reactions of free radicals with oxygen in solution

    International Nuclear Information System (INIS)

    Maillard, B.; Ingold, K.U.; Scaiano, J.C.

    1983-01-01

    The kinetics of the rections of several free radicals with oxygen have been examined in solution at 300 K using laser flash photolysis techniques. The reactions of resonance-stabilized radicals are only slightly slower than those of nonstabilized radicals: for example, for tert-butyl (in cyclohexane), 4.93 x 10 9 ; benzyl, 2.36 x 10 9 (in cyclohexane); cyclohexadienyl (in benzene), 1.64 x 10 9 M -1 s -1 . The reaction of butyl-tin (n-Bu 3 Sn.) radicals is unusually fast (7.5 x 10 9 M -1 s -1 ), a fact that has been tentatively attributed to a relaxation of spin selection rules due to heavy atom effects. 1 table

  1. [Evaluation of heart impact in the 100 m extreme intensity sport using near-infrared non-invasive muscle oxygen detecting device and sports heart rate detection technology].

    Science.gov (United States)

    Wang, Pei-Yong; Long, Fei-Xiao; Fu, Lan-Ying; Li, Yue; Ding, Hai-Shu; Qu, An-Lian; Zhou, Xiao-Ping

    2010-02-01

    Using continuous two wavelength near-infrared technology to detect the variation in the consistency of oxygen hemoglobin in the muscle and the sports heart rate wireless real time collection technology, we devised the real time muscle tissue oxygenation and instantaneous heart rate experiment scheme and implemented it for the process of the 100 m run with two parameters given simultaneously. The experiment shows that the concentration of the oxygen hemoglobin in the muscle tissue continues decreasing after the end of the 100 m run, and the time interval between the moment when the concentration of the oxygen hemoglobin attains the minimum value and the moment when the athletes finish the 100 m run is (6.65 +/- 1.10) sec; while the heart rate continues increasing after the end of the 100 m run, and the time interval between the moment when the heart rate attains the maximum value and the moment when the athletes finish the 100 m run is (8.00 +/- 1.57) sec. The results show that the two wavelength near-infrared tissue oxygenation detection technology and the sports heart rate real time collection equipment can accurately measure the sports tissue oxygenation and the heart rate in the extreme intensity sport, and reveal the process of muscle oxygen transportation and consumption and its dynamic character with the heart rate in the extreme intensity sport.

  2. Reactive Oxygen Species Production by Forward and Reverse Electron Fluxes in the Mitochondrial Respiratory Chain

    Science.gov (United States)

    Selivanov, Vitaly A.; Votyakova, Tatyana V.; Pivtoraiko, Violetta N.; Zeak, Jennifer; Sukhomlin, Tatiana; Trucco, Massimo; Roca, Josep; Cascante, Marta

    2011-01-01

    Reactive oxygen species (ROS) produced in the mitochondrial respiratory chain (RC) are primary signals that modulate cellular adaptation to environment, and are also destructive factors that damage cells under the conditions of hypoxia/reoxygenation relevant for various systemic diseases or transplantation. The important role of ROS in cell survival requires detailed investigation of mechanism and determinants of ROS production. To perform such an investigation we extended our rule-based model of complex III in order to account for electron transport in the whole RC coupled to proton translocation, transmembrane electrochemical potential generation, TCA cycle reactions, and substrate transport to mitochondria. It fits respiratory electron fluxes measured in rat brain mitochondria fueled by succinate or pyruvate and malate, and the dynamics of NAD+ reduction by reverse electron transport from succinate through complex I. The fitting of measured characteristics gave an insight into the mechanism of underlying processes governing the formation of free radicals that can transfer an unpaired electron to oxygen-producing superoxide and thus can initiate the generation of ROS. Our analysis revealed an association of ROS production with levels of specific radicals of individual electron transporters and their combinations in species of complexes I and III. It was found that the phenomenon of bistability, revealed previously as a property of complex III, remains valid for the whole RC. The conditions for switching to a state with a high content of free radicals in complex III were predicted based on theoretical analysis and were confirmed experimentally. These findings provide a new insight into the mechanisms of ROS production in RC. PMID:21483483

  3. Temperature response of denitrification rate and greenhouse gas production in agricultural river marginal wetland soils.

    Science.gov (United States)

    Bonnett, S A F; Blackwell, M S A; Leah, R; Cook, V; O'Connor, M; Maltby, E

    2013-05-01

    Soils are predicted to exhibit significant feedback to global warming via the temperature response of greenhouse gas (GHG) production. However, the temperature response of hydromorphic wetland soils is complicated by confounding factors such as oxygen (O2 ), nitrate (NO3-) and soil carbon (C). We examined the effect of a temperature gradient (2-25 °C) on denitrification rates and net nitrous oxide (N2 O), methane (CH4 ) production and heterotrophic respiration in mineral (Eutric cambisol and Fluvisol) and organic (Histosol) soil types in a river marginal landscape of the Tamar catchment, Devon, UK, under non-flooded and flooded with enriched NO3- conditions. It was hypothesized that the temperature response is dependent on interactions with NO3--enriched flooding, and the physicochemical conditions of these soil types. Denitrification rate (mean, 746 ± 97.3 μg m(-2)  h(-1) ), net N2 O production (mean, 180 ± 26.6 μg m(-2)  h(-1) ) and net CH4 production (mean, 1065 ± 183 μg m(-2)  h(-1) ) were highest in the organic Histosol, with higher organic matter, ammonium and moisture, and lower NO3- concentrations. Heterotrophic respiration (mean, 127 ± 4.6 mg m(-2)  h(-1) ) was not significantly different between soil types and dominated total GHG (CO2 eq) production in all soil types. Generally, the temperature responses of denitrification rate and net N2 O production were exponential, whilst net CH4 production was unresponsive, possibly due to substrate limitation, and heterotrophic respiration was exponential but limited in summer at higher temperatures. Flooding with NO3- increased denitrification rate, net N2 O production and heterotrophic respiration, but a reduction in net CH4 production suggests inhibition of methanogenesis by NO3- or N2 O produced from denitrification. Implications for management and policy are that warming and flood events may promote microbial interactions in soil between distinct microbial communities and increase

  4. Dust appearance rates during neutral beam injection and after oxygen bake in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Yu, J.H.; Smirnov, R.D.; Rudakov, D.L.

    2011-01-01

    A simple model to quantify source and sink terms of dust observed in tokamaks using fast visible imaging is presented. During neutral beam injection (NBI), dust appearance rates increase in front of the neutral beam port by up to a factor of 5. The images show dust streaming from the port box as previously settled dust becomes mobilized during beam injection. Following an oxygen bake and vent, the dust observation rate is a factor of 2 lower than that after a vessel entry vent with no oxygen bake. Detected dust levels decay on a shot-to-shot basis in a roughly exponential fashion, with a decay time of approximately 20 s of plasma exposure. Appearance rates of dust mass are estimated using assumed lognormal and power law functional forms for the dust size distribution. The two dust size distributions differ significantly on the amount the dust material carried by the largest particles, highlighting the need for further dust studies in order to make accurate forecasts to ITER.

  5. Friend or foe? Reactive oxygen species production, scavenging and signaling in plant response to environmental stresses.

    Science.gov (United States)

    Czarnocka, Weronika; Karpiński, Stanisław

    2018-01-10

    In the natural environment, plants are exposed to a variety of biotic and abiotic stress conditions that trigger rapid changes in the production and scavenging of reactive oxygen species (ROS). The production and scavenging of ROS is compartmentalized, which means that, depending on stimuli type, they can be generated and eliminated in different cellular compartments such as the apoplast, plasma membrane, chloroplasts, mitochondria, peroxisomes, and endoplasmic reticulum. Although the accumulation of ROS is generally harmful to cells, ROS play an important role in signaling pathways that regulate acclimatory and defense responses in plants, such as systemic acquired acclimation (SAA) and systemic acquired resistance (SAR). However, high accumulations of ROS can also trigger redox homeostasis disturbance which can lead to cell death, and in consequence, to a limitation in biomass and yield production. Different ROS have various half-lifetimes and degrees of reactivity toward molecular components such as lipids, proteins, and nucleic acids. Thus, they play different roles in intra- and extra-cellular signaling. Despite their possible damaging effect, ROS should mainly be considered as signaling molecules that regulate local and systemic acclimatory and defense responses. Over the past two decades it has been proven that ROS together with non-photochemical quenching (NPQ), hormones, Ca 2+ waves, and electrical signals are the main players in SAA and SAR, two physiological processes essential for plant survival and productivity in unfavorable conditions. Copyright © 2018. Published by Elsevier Inc.

  6. A Quantitative Method to Monitor Reactive Oxygen Species Production by Electron Paramagnetic Resonance in Physiological and Pathological Conditions

    Science.gov (United States)

    Mrakic-Sposta, Simona; Gussoni, Maristella; Montorsi, Michela; Porcelli, Simone; Vezzoli, Alessandra

    2014-01-01

    The growing interest in the role of Reactive Oxygen Species (ROS) and in the assessment of oxidative stress in health and disease clashes with the lack of consensus on reliable quantitative noninvasive methods applicable. The study aimed at demonstrating that a recently developed Electron Paramagnetic Resonance microinvasive method provides direct evidence of the “instantaneous” presence of ROS returning absolute concentration levels that correlate with “a posteriori” assays of ROS-induced damage by means of biomarkers. The reliability of the choice to measure ROS production rate in human capillary blood rather than in plasma was tested (step I). A significant (P < 0.01) linear relationship between EPR data collected on capillary blood versus venous blood (R 2 = 0.95), plasma (R 2 = 0.82), and erythrocytes (R 2 = 0.73) was found. Then (step II) ROS production changes of various subjects' categories, young versus old and healthy versus pathological at rest condition, were found significantly different (range 0.0001–0.05 P level). The comparison of the results with antioxidant capacity and oxidative damage biomarkers concentrations showed that all changes indicating increased oxidative stress are directly related to ROS production increase. Therefore, the adopted method may be an automated technique for a lot of routine in clinical trials. PMID:25374651

  7. Ameliorative effects of low dose/low dose-rate irradiation on reactive oxygen species-related diseases model mice

    International Nuclear Information System (INIS)

    Nomura, Takaharu

    2008-01-01

    Living organisms have developed complex biological system which protects themselves against environmental radiation, and irradiation with proper dose, dose-rate and irradiation time can stimulate their biological responses against oxidative stress evoked by the irradiation. Because reactive oxygen species are involved in various human diseases, non-toxic low dose/low dose-rate radiation can be utilized for the amelioration of such diseases. In this study, we used mouse experimental models for fatty liver, nephritis, diabetes, and ageing to elucidate the ameliorative effect of low dose/low dose-rate radiation in relation to endogenous antioxidant activity. Single irradiation at 0.5 Gy ameliorates carbon tetrachloride-induced fatty liver. The irradiation increases hepatic anti-oxidative system involving glutathione and glutathione peroxidase, suggesting that endogenous radical scavenger is essential for the ameliorative effect of low dose radiation on carbon tetrachloride-induced fatty liver. Single irradiation at 0.5 Gy ameliorates ferric nitrilotriacetate-induced nephritis. The irradiation increases catalase and decreases superoxide dismutase in kidney. The result suggests that low dose radiation reduced generation of hydroxide radical generation by reducing cellular hydroperoxide level. Single irradiation at 0.5 Gy at 12 week of age ameliorates incidence of type I diabetes in non-obese diabetic (NOD) mice through the suppression of inflammatory activity of splenocytes, and resultant apoptosis of β-cells in pancreas. The irradiation activities of superoxide dismutase and catalase, which coordinately diminish intracellular reactive oxygen species. Continuous irradiation at 0.70 mGy/hr from 10 week of age elongates life span, and suppresses alopecia in type II diabetesmice. The irradiation improved glucose clearance without affecting insulin-resistance, and increased pancreatic catalase activity. The results suggest that continuous low dose-rate irradiation protect

  8. Activity of the respiratory electron transport system and respiration rates within the oxygen minimum layer of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Shailaja, M.S.

    rates. The depth profiles representing observations off Peru and Mexico are also shown. It may be noted that the measurements off Mexico were made with a method similar to that followed by us (GARFIELD et al., 1983). On the other hand, the Peruvian... judging from the nitrate deficit, nitrite and nitrous oxide distributions (NAQvI and NORONHA, 1991). OXYGEN CONSUMPTION (nl./t/h) 0 q 20 40 60 80 , n i I i I00 Off Mexico • • /~ "f~ Off Peru o o / 200 ,o ~ ~ - o o I • " e o //-o-./ - - 400 tR~•7...

  9. A survey of the reaction rate constants for the thermal dissociation and recombination of nitrogen and oxygen

    Science.gov (United States)

    Marraffa, Lionel; Dulikravich, George S.; Keeney, Timothy C.; Deiwert, George S.

    1988-01-01

    The objective of the present report is to survey the various values of forward and backward reaction rate constants used by investigators in the field of high-temperature (T greater than 2000 K) gas reactions involving nitrogen and oxygen only. The objective is to find those values that correlate well so that they can be used for the studies of hypersonic flow and supersonic combustion with reasonable confidence. Relatively good agreement among these various values is observed for temperatures lower than 10,000 K.

  10. [Proceeding: Production rate, metabolic clearance rate and mean plasma concentration of cortisol in hyperthyroidism (author's transl)].

    Science.gov (United States)

    Linquette, M; Lefebvre, J; Racadot, A; Cappoen, J P

    1975-01-01

    The adrenocortical function was studied in 23 patients with hyperthyroidism and compared with a group of 15 normal subjects. Parameters of adrenal function were determined with 1,2(3)H-cortisol. The half-life of cortisol is significantly shortened in hyperthyroidism, as compared to normal subjects (49,5 +/- 6,6 min vs 68,3 +/- 10,5 min) and metabolic clearance rate is increased (418,5 +/- 89,5 L/24 h vs 237,5 +/- 48,5 L/24 h, for normal subjects). The production rate of cortisol, calculated from specific and cumulate activities of THE and THF is increased in hyperthyroidism expressed as mg/24 h or mg/m2/24 h (respectively : 26,7 +/- 7,8 mg/24 h vs 15,7 +/- 3 mg/24 h and 16,9 +/- 4,6 mg/m2/24 h vs 9,5 +/- 1,8 mg/m2/24 h). The mean plasma concentration, calculated as the radio (see article) is not statiscally different in hyperthyroid and normal subjects (6,8 +/- 2,1 microg/100 ml vs 7,3 +/- 1,9 microg/100 ml). 7 patients were reinvestigated after treatment of thyrotoxicosis when they were clinically and biologically in euthyroid state. All the values were normalized, without statistically significant difference from control (T 1/2 = 65,4 +/- 18 min, Metb Cl. Rate : 255 +/- 64,5 L/24 h, production rate : 15,6 +/- 1,8 mg/24 h and 9 +/- 1,4 mg/m2/24 h. mean plasma concentration : 6,8 +/- 2,8 microg/100 ml). Shortened cortisol half life, increased metabolic clearance rate and production rate, and normal mean plasma concentration have been reported in hyperthyroidism (Peterson, Copinschi, Gallagher). These changes, secondary to thyroid hormone excess, are the consequences of increased hepatic catabolism of cortisol. The activity of 11 OH steroid deshydrogenase is increased, as demonstrated by increased ratio (see article) in normal subjects (0,001 less than p less than 0,005). There is a high proportion of 17 kéto metabolites (E, DHE, THE) whose feed-back effect is weak as compared to 17 OH metabolites (F, DHF, THF). The hypothalamo-hypophyso-adrenal system is

  11. The production rate of cosmogenic deuterium at the Moon's surface

    Science.gov (United States)

    Füri, Evelyn; Deloule, Etienne; Trappitsch, Reto

    2017-09-01

    The hydrogen (D/H) isotope ratio is a key tracer for the source of planetary water. However, secondary processes such as solar wind implantation and cosmic ray induced spallation reactions have modified the primordial D/H signature of 'water' in all rocks and soils recovered on the Moon. Here, we re-evaluate the production rate of cosmogenic deuterium (D) at the Moon's surface through ion microprobe analyses of hydrogen isotopes in olivines from eight Apollo 12 and 15 mare basalts. These in situ measurements are complemented by CO2 laser extraction-static mass spectrometry analyses of cosmogenic noble gas nuclides (3He, 21Ne, 38Ar). Cosmic ray exposure (CRE) ages of the mare basalts, derived from their cosmogenic 21Ne content, range from 60 to 422 Ma. These CRE ages are 35% higher, on average, than the published values for the same samples. The amount of D detected in the olivines increases linearly with increasing CRE ages, consistent with a production rate of (2.17 ± 0.11) ×10-12 mol(g rock)-1 Ma-1. This value is more than twice as high as previous estimates for the production of D by galactic cosmic rays, indicating that for water-poor lunar samples, i.e., samples with water concentrations ≤50 ppm, corrected D/H ratios have been severely overestimated.

  12. Reactive oxygen species and lipid peroxidation product-scavenging ability of yogurt organisms.

    Science.gov (United States)

    Lin, M Y; Yen, C L

    1999-08-01

    The antioxidative activity of the intracellular extracts of yogurt organisms was investigated. All 11 strains tested, including five strains of Streptococcus thermophilus and six strains of Lactobacillus delbrueckii ssp. bulgaricus, demonstrated an antioxidative effect on the inhibition of linoleic acid peroxidation. The antioxidative effect of intracellular extracts of 10(8) cells of yogurt organisms was equivalent to 25 to 96 ppm butylated hydroxytoluene, which indicated that all strains demonstrated excellent antioxidative activity. The scavenging of reactive oxygen species, hydroxyl radical, and hydrogen peroxide was studied for intracellular extracts of yogurt organisms. All strains showed reactive oxygen species-scavenging ability. Lactobacillus delbrueckii ssp. bulgaricus Lb demonstrated the highest hydroxyl radical-scavenging ability at 234 microM. Streptococcus thermophilus MC and 821 and L. delbrueckii ssp. bulgaricus 448 and 449 scavenged the most hydrogen peroxide at approximately 50 microM. The scavenging ability of lipid peroxidation products, t-butylhydroperoxide and malondialdehyde, was also evaluated. Results showed that the extracts were not able to scavenge the t-butylhydroperoxide. Nevertheless, malondialdehyde was scavenged well by most strains.

  13. From Oxygen Generation to Metals Production: In Situ Resource Utilization by Molten Oxide Electrolysis

    Science.gov (United States)

    Khetpal, Deepak; Ducret, Andrew C.; Sadoway, Donald R.

    2003-01-01

    For the exploration of other bodies in the solar system, electrochemical processing is arguably the most versatile technology for conversion of local resources into usable commodities: by electrolysis one can, in principle, produce (1) breathable oxygen, (2) silicon for the fabrication of solar cells, (3) various reactive metals for use as electrodes in advanced storage batteries, and (4) structural metals such as steel and aluminum. Even so, to date there has been no sustained effort to develop such processes, in part due to the inadequacy of the database. The objective here is to identify chemistries capable of sustaining molten oxide electrolysis in the cited applications and to examine the behavior of laboratory-scale cells designed to generate oxygen and to produce metal. The basic research includes the study of the underlying high-temperature physical chemistry of oxide melts representative of lunar regolith and of Martian soil. To move beyond empirical approaches to process development, the thermodynamic and transport properties of oxide melts are being studied to help set the limits of composition and temperature for the processing trials conducted in laboratory-scale electrolysis cells. The goal of this investigation is to deliver a working prototype cell that can use lunar regolith and Martian soil to produce breathable oxygen along with metal by-product. Additionally, the process can be generalized to permit adaptation to accommodate different feedstock chemistries, such as those that will be encountered on other bodies in the solar system. The expected results of this research include: (1) the identification of appropriate electrolyte chemistries; (2) the selection of candidate anode and cathode materials compatible with electrolytes named above; and (3) performance data from a laboratory-scale cell producing oxygen and metal. On the strength of these results it should be possible to assess the technical viability of molten oxide electrolysis for in

  14. Lifetime and production rate of beauty baryons from Z decays

    CERN Document Server

    Abreu, P; Adye, T; Agasi, E; Ajinenko, I; Aleksan, Roy; Alekseev, G D; Allport, P P; Almehed, S; Alvsvaag, S J; Amaldi, Ugo; Amato, S; Andreazza, A; Andrieux, M L; Antilogus, P; Apel, W D; Arnoud, Y; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barão, F; Barate, R; Barbiellini, Guido; Bardin, Dimitri Yuri; Barker, G J; Baroncelli, A; Bärring, O; Barrio, J A; Bartl, Walter; Bates, M J; Battaglia, Marco; Baubillier, M; Baudot, J; Becks, K H; Begalli, M; Beillière, P; Belokopytov, Yu A; Benvenuti, Alberto C; Berggren, M; Bertrand, D; Bianchi, F; Bigi, M; Bilenky, S M; Billoir, P; Bloch, D; Blume, M; Blyth, S; Bocci, V; Bolognese, T; Bonesini, M; Bonivento, W; Booth, P S L; Borisov, G; Bosio, C; Bosworth, S; Botner, O; Bouquet, B; Bourdarios, C; Bowcock, T J V; Bozzo, M; Branchini, P; Brand, K D; Brenner, R A; Bricman, C; Brillault, L; Brown, R C A; Brückman, P; Brunet, J M; Bugge, L; Buran, T; Buys, A; Caccia, M; Calvi, M; Camacho-Rozas, A J; Camporesi, T; Canale, V; Canepa, M; Cankocak, K; Cao, F; Carena, F; Carrilho, P; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Cerrito, L; Chabaud, V; Chapkin, M M; Charpentier, P; Chaussard, L; Chauveau, J; Checchia, P; Chelkov, G A; Chierici, R; Chliapnikov, P V; Chochula, P; Chorowicz, V; Cindro, V; Collins, P; Contreras, J L; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Crawley, H B; Crennell, D J; Crosetti, G; Cuevas-Maestro, J; Czellar, S; Dahl-Jensen, Erik; Dahm, J; D'Almagne, B; Dam, M; Damgaard, G; Daum, A; Dauncey, P D; Davenport, Martyn; Da Silva, W; Defoix, C; Della Ricca, G; Delpierre, P A; Demaria, N; De Angelis, A; De Boeck, H; de Boer, Wim; De Brabandere, S; De Clercq, C; La Vaissière, C de; De Lotto, B; De Min, A; De Paula, L S; De Saint-Jean, C; Dijkstra, H; Di Ciaccio, Lucia; Djama, F; Dolbeau, J; Dönszelmann, M; Doroba, K; Dracos, M; Drees, J; Drees, K A; Dris, M; Dufour, Y; Dupont, F; Edsall, D M; Ehret, R; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Elsing, M; Engel, J P; Ershaidat, N; Erzen, B; Espirito-Santo, M C; Falk, E; Fassouliotis, D; Feindt, Michael; Fenyuk, A; Ferrer, A; Filippas-Tassos, A; Firestone, A; Föth, H; Fokitis, E; Fontanelli, F; Formenti, F; Franek, B J; Frenkiel, P; Fries, D E C; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fürstenau, H; Fuster, J A; Galloni, A; Gamba, D; Gandelman, M; García, C; García, J; Gaspar, C; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Gerber, J P; Gibbs, M; Gillespie, D; Gokieli, R; Golob, B; Gopal, Gian P; Gorn, L; Górski, M; Gracco, Valerio; Graziani, E; Grosdidier, G; Gunnarsson, P; Günther, M; Guy, J; Haedinger, U; Hahn, F; Hahn, M; Hahn, S; Hajduk, Z; Hallgren, A; Hamacher, K; Hao, W; Harris, F J; Hedberg, V; Henriques, R P; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Higón, E; Hilke, Hans Jürgen; Hill, T S; Holmgren, S O; Holt, P J; Holthuizen, D J; Houlden, M A; Hrubec, Josef; Huet, K; Hultqvist, K; Ioannou, P; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Jönsson, L B; Jönsson, P E; Joram, Christian; Juillot, P; Kaiser, M; Kalmus, George Ernest; Kapusta, F; Karlsson, M; Karvelas, E; Katsanevas, S; Katsoufis, E C; Keränen, R; Khomenko, B A; Khovanskii, N N; King, B J; Kjaer, N J; Klein, H; Klovning, A; Kluit, P M; Köhne, J H; Köne, B; Kokkinias, P; Koratzinos, M; Kostyukhin, V; Kourkoumelis, C; Kuznetsov, O; Kramer, P H; Krammer, Manfred; Kreuter, C; Królikowski, J; Kronkvist, I J; Krumshtein, Z; Krupinski, W; Kubinec, P; Kucewicz, W; Kurvinen, K L; Lacasta, C; Laktineh, I; Lamblot, S; Lamsa, J; Lanceri, L; Lane, D W; Langefeld, P; Lapin, V; Last, I; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Legan, C K; Leitner, R; Lemoigne, Y; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Liko, D; Lindner, R; Lipniacka, A; Lippi, I; Lörstad, B; Lokajícek, M; Loken, J G; López, J M; López-Fernandez, A; López-Aguera, M A; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J N; Maehlum, G; Maio, A; Malychev, V; Mandl, F; Marco, J; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Maron, T; Martínez-Rivero, C; Martínez-Vidal, F; Martí i García, S; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Mazzucato, M; McCubbin, M L; McKay, M; McNulty, M; Medbo, J; Meroni, C; Meyer, W T; Michelotto, M; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Møller, R; Mönig, K; Monge, M R; Morettini, P; Müller, H; Mundim, L M; Murray, W J; Muryn, B; Myatt, Gerald; Naraghi, F; Navarria, Francesco Luigi; Navas, S; Negri, P; Némécek, S; Neumann, W; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nieuwenhuizen, M; Nikolaenko, V; Niss, P; Nomerotski, A; Normand, Ainsley; Oberschulte-Beckmann, W; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Ostankov, A P; Österberg, K; Ouraou, A; Paganini, P; Paganoni, M; Pagès, P; Palka, H; Papadopoulou, T D; Pape, L; Parkes, C; Parodi, F; Passeri, A; Pegoraro, M; Peralta, L; Pernegger, H; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Phillips, H T; Piana, G; Pierre, F; Plaszczynski, S; Podobrin, O; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Prest, M; Privitera, P; Pukhaeva, N; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Rames, J; Ratoff, P N; Read, A L; Reale, M; Rebecchi, P; Redaelli, N G; Reid, D; Renton, P B; Resvanis, L K; Richard, F; Richardson, J; Rídky, J; Rinaudo, G; Ripp, I; Romero, A; Roncagliolo, I; Ronchese, P; Roos, L; Rosenberg, E I; Rosso, E; Roudeau, Patrick; Rovelli, T; Rückstuhl, W; Ruhlmann-Kleider, V; Ruiz, A; Rybicki, K; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sajot, G; Salt, J; Sánchez, J; Sannino, M; Schneider, H; Schyns, M A E; Sciolla, G; Scuri, F; Sedykh, Yu; Segar, A M; Seitz, A; Sekulin, R L; Shellard, R C; Siccama, I; Siegrist, P; Simonetti, S; Simonetto, F; Sissakian, A N; Sitár, B; Skaali, T B; Smadja, G; Smirnov, N; Smirnova, O G; Smith, G R; Sosnowski, R; Souza-Santos, D; Spassoff, Tz; Spiriti, E; Squarcia, S; Stäck, H; Stanescu, C; Stapnes, Steinar; Stavitski, I; Stepaniak, K; Stichelbaut, F; Stocchi, A; Strauss, J; Strub, R; Stugu, B; Szczekowski, M; Szeptycka, M; Tabarelli de Fatis, T; Tavernet, J P; Chikilev, O G; Tilquin, A; Timmermans, J; Tkatchev, L G; Todorov, T; Toet, D Z; Tomaradze, A G; Tomé, B; Torassa, E; Tortora, L; Tranströmer, G; Treille, D; Trischuk, W; Tristram, G; Trombini, A; Troncon, C; Tsirou, A L; Turluer, M L; Tyapkin, I A; Tyndel, M; Tzamarias, S; Überschär, B; Überschär, S; Ullaland, O; Uvarov, V; Valenti, G; Vallazza, E; van Apeldoorn, G W; van Dam, P; Van Doninck, W K; Van Eldik, J; Vassilopoulos, N; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Vilanova, D; Vincent, P; Vitale, L; Vlasov, E; Vodopyanov, A S; Vrba, V; Wahlen, H; Walck, C; Wehr, A; Weierstall, M; Weilhammer, Peter; Wetherell, Alan M; Wicke, D; Wickens, J H; Wielers, M; Wilkinson, G R; Williams, W S C; Winter, M; Witek, M; Wormser, G; Woschnagg, K; Yip, K; Zach, F; Zacharatou-Jarlskog, C; Zaitsev, A; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zito, M; Zontar, D; Zuberi, R; Zucchelli, G C; Zumerle, G

    1995-01-01

    The production and decay of beauty baryons (b-baryons) have been studied using 1.7 \\times 10^6 Z hadronic decays collected by the DELPHI detector at LEP. Three different techniques were used to identify the b-baryons. The first method used pairs of a \\Lambda and a lepton to tag the b-baryon decay. The second method associated fully reconstructed \\Lambda_c baryons with leptons. The third analysis reconstructed the b-baryon decay points by forming secondary vertices from identified protons and muons of opposite sign. Using these methods the following production rates were measured: \\begin{eqnarray*} f(\\qb \\ra \\Bb) \\times \\BR(\\Bb \\ra \\mLs \\ell\\bar{\

  15. The Production Rate and Employment of Ph.D. Astronomers

    Science.gov (United States)

    Metcalfe, Travis S.

    2008-02-01

    In an effort to encourage self-regulation of the astronomy job market, I examine the supply of, and demand for, astronomers over time. On the supply side, I document the production rate of Ph.D. astronomers from 1970 to 2006 using the UMI Dissertation Abstracts database, along with data from other independent sources. I compare the long-term trends in Ph.D. production with federal astronomy research funding over the same time period, and I demonstrate that additional funding is correlated with higher subsequent Ph.D. production. On the demand side, I monitor the changing patterns of employment using statistics about the number and types of jobs advertised in the AAS Job Register from 1984 to 2006. Finally, I assess the sustainability of the job market by normalizing this demand by the annual Ph.D. production. The most recent data suggest that there are now annual advertisements for about one postdoctoral job, half a faculty job, and half a research/support position for every new domestic Ph.D. recipient in astronomy and astrophysics. The average new astronomer might expect to hold up to 3 jobs before finding a steady position.

  16. Visible-light activate Ag/WO3 films based on wood with enhanced negative oxygen ions production properties

    Science.gov (United States)

    Gao, Likun; Gan, Wentao; Cao, Guoliang; Zhan, Xianxu; Qiang, Tiangang; Li, Jian

    2017-12-01

    The Ag/WO3-wood was fabricated through a hydrothermal method and a silver mirror reaction. The system of visible-light activate Ag/WO3-wood was used to produce negative oxygen ions, and the effect of Ag nanoparticles on negative oxygen ions production was investigated. From the results of negative oxygen ions production tests, it can be observed that the sample doped with Ag nanoparticles, the concentration of negative oxygen ions is up to 1660 ions/cm3 after 60 min visible light irradiation. Moreover, for the Ag/WO3-wood, even after 60 min without irradiation, the concentration of negative oxygen ions could keep more than 1000 ions/cm3, which is up to the standard of the fresh air. Moreover, due to the porous structure of wood, the wood acted as substrate could promote the nucleation of nanoparticles, prevent the agglomeration of the particles, and thus lead the improvement of photocatalytic properties. And such wood-based functional materials with the property of negative oxygen ions production could be one of the most promising materials in the application of indoor decoration materials, which would meet people's pursuit of healthy, environment-friendly life.

  17. Substrates and oxygen dependent citric acid production by Yarrowia lipolytica: insights through transcriptome and fluxome analyses.

    Science.gov (United States)

    Sabra, Wael; Bommareddy, Rajesh Reddy; Maheshwari, Garima; Papanikolaou, Seraphim; Zeng, An-Ping

    2017-05-08

    Unlike the well-studied backer yeast where catabolite repression represents a burden for mixed substrate fermentation, Yarrowia lipolytica, an oleaginous yeast, is recognized for its potential to produce single cell oils and citric acid from different feedstocks. These versatilities of Y. lipolytica with regards to substrate utilization make it an attractive host for biorefinery application. However, to develop a commercial process for the production of citric acid by Y. lipolytica, it is necessary to better understand the primary metabolism and its regulation, especially for growth on mixed substrate. Controlling the dissolved oxygen concentration (pO 2 ) in Y. lipolytica cultures enhanced citric acid production significantly in cultures grown on glucose in mono- or dual substrate fermentations, whereas with glycerol as mono-substrate no significant effect of pO 2 was found on citrate production. Growth on mixed substrate with glucose and glycerol revealed a relative preference of glycerol utilization by Y. lipolytica. Under optimized conditions with pO 2 control, the citric acid titer on glucose in mono- or in dual substrate cultures was 55 and 50 g/L (with productivity of 0.6 g/L*h in both cultures), respectively, compared to a maximum of 18 g/L (0.2 g/L*h) with glycerol in monosubstrate culture. Additionally, in dual substrate fermentation, glycerol limitation was found to trigger citrate consumption despite the presence of enough glucose in pO 2 -limited culture. The metabolic behavior of this yeast on different substrates was investigated at transcriptomic and 13 C-based fluxomics levels. Upregulation of most of the genes of the pentose phosphate pathway was found in cultures with highest citrate production with glucose in mono- or in dual substrate fermentation with pO 2 control. The activation of the glyoxylate cycle in the oxygen limited cultures and the imbalance caused by glycerol limitation might be the reason for the re-consumption of citrate in

  18. Elevated global cerebral blood flow, oxygen extraction fraction and unchanged metabolic rate of oxygen in young adults with end-stage renal disease: an MRI study.

    Science.gov (United States)

    Zheng, Gang; Wen, Jiqiu; Lu, Hanzhang; Lou, Yaxian; Pan, Zhiying; Liu, Wei; Liu, Hui; Li, Xue; Zhang, Zhe; Chen, Huijuan; Kong, Xiang; Luo, Song; Jiang, Xiaolu; Liu, Ya; Zhang, Zongjun; Zhang, Long Jiang; Lu, Guang Ming

    2016-06-01

    To noninvasively assess global cerebral blood flow (CBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) in young adults with end-stage renal disease (ESRD). Thirty-six patients and 38 healthy volunteers were included and took part in MR examinations, blood and neuropsychological tests. CBF and OEF were measured by phase-contrast and T2-relaxation-under-spin-tagging MRI techniques, respectively. CMRO2 was computed from CBF, OEF and hematocrit according to Fick's principle. Correlations were performed between MR measurements, blood biochemistry measurements and neuropsychological test scores. Compared with controls, ESRD patients had elevated CBF (72.9 ± 12.5 vs. 63.8 ± 8.5 ml min(-1) 100 g(-1), P < 0.001), elevated OEF (47.2 ± 10.2 vs. 35.8 ± 5.4 %, P < 0.001), but unaffected CMRO2 (199.5 ± 36.4 vs. 193.8 ± 28.6 μmol O2 min(-1) 100 g(-1), P = 0.879). Hematocrit negatively correlated with CBF (r = -0.640, P < 0.001) and OEF (r = -0.701, P < 0.001), but not with CMRO2. Altered neuropsychological test scores of ESRD patients were associated with OEF and CBF, but not with CMRO2. There were weak relationships between eGFR and hematocrit (r = 0.308, P = 0.068) or CBF (r = 0.318, P = 0.059). Our findings suggested that anaemic young adults with ESRD may afford higher CBF and OEF to maintain a normal CMRO2. Despite this compensatory process, however, cognitive function was still impaired and its severity was correlated with their CBF and OEF abnormality. • Anaemic young adults with ESRD may afford higher CBF and OEF. • Anaemic young adults with ESRD maintain a normal CMRO 2 . • Cognitive function was still impaired in young ESRD adults. • The severity of cognitive dysfunction correlated with CBF and OEF changes.

  19. Heart Rate and Oxygen Uptake Kinetics in Type 2 Diabetes Patients - A Pilot Study on the Influence of Cardiovascular Medication on Regulatory Processes.

    Science.gov (United States)

    Koschate, Jessica; Drescher, Uwe; Baum, Klaus; Brinkmann, Christian; Schiffer, Thorsten; Latsch, Joachim; Brixius, Klara; Hoffmann, Uwe

    2017-05-01

    The aim of this pilot study was to investigate whether there are differences in heart rate and oxygen uptake kinetics in type 2 diabetes patients, considering their cardiovascular medication. It was hypothesized that cardiovascular medication would affect heart rate and oxygen uptake kinetics and that this could be detected using a standardized exercise test. 18 subjects were tested for maximal oxygen uptake. Kinetics were measured in a single test session with standardized, randomized moderate-intensity work rate changes. Time series analysis was used to estimate kinetics. Greater maxima in cross-correlation functions indicate faster kinetics. 6 patients did not take any cardiovascular medication, 6 subjects took peripherally acting medication and 6 patients were treated with centrally acting medication. Maximum oxygen uptake was not significantly different between groups. Significant main effects were identified regarding differences in muscular oxygen uptake kinetics and heart rate kinetics. Muscular oxygen uptake kinetics were significantly faster than heart rate kinetics in the group with no cardiovascular medication (maximum in cross-correlation function of muscular oxygen uptake vs. heart rate; 0.32±0.08 vs. 0.25±0.06; p=0.001) and in the group taking peripherally acting medication (0.34±0.05 vs. 0.28±0.05; p=0.009) but not in the patients taking centrally acting medication (0.28±0.05 vs. 0.30±0.07; n.s.). It can be concluded that regulatory processes for the achievement of a similar maximal oxygen uptake are different between the groups. The used standardized test provided plausible results for heart rate and oxygen uptake kinetics in a single measurement session in this patient group. © Georg Thieme Verlag KG Stuttgart · New York.

  20. [Comparison of reactive oxygen species production in neat semen and washed spermatozoa].

    Science.gov (United States)

    Svobodová, M; Oborná, I; Fingerová, H; Novotný, J; Brezinová, J; Radová, L; Vyslouzilová, J; Horáková, J; Grohmannová, J

    2009-12-01

    To determine Reactive Oxygen Species (ROS) production in neat semen and spermatozoa suspension using chemiluminescence and to examine correlation between both methods. Prospective laboratory study. Department of Obstetric and Gynecology, University Hospital, Olomouc. The study included fertile volunteers (FV, n = 17), men from infertile couples (NM, n = 19) and men with idiopathic infertility (NMI, n = 15). ROS levels were determined by the same method in neat and washed semen samples. The ROS production in neat semen was lower than that in spermatozoa suspension. There was no significant diference in ROS production between volunteers and males from infertile couples. There was a significant correlation between log ROS in neat semen and in spermatozoa suspension in studied groups (FV r = 0.85, p = 1.5 x 10(-5); NM r = 0.76, p neat semen is simpler, faster and better reflecting the actual level of oxidative stress than the same measurement in spermatozoa suspension. The implementation of this method can complement the algorithm of diagnostics and treatment of male infertility and be helpful in selection of patients for antioxidant or antibiotic treatment.

  1. Air-adapted Methanosarcina acetivorans shows high methane production and develops resistance against oxygen stress.

    Directory of Open Access Journals (Sweden)

    Ricardo Jasso-Chávez

    Full Text Available Methanosarcina acetivorans, considered a strict anaerobic archaeon, was cultured in the presence of 0.4-1% O2 (atmospheric for at least 6 months to generate air-adapted cells; further, the biochemical mechanisms developed to deal with O2 were characterized. Methane production and protein content, as indicators of cell growth, did not change in air-adapted cells respect to cells cultured under anoxia (control cells. In contrast, growth and methane production significantly decreased in control cells exposed for the first time to O2. Production of reactive oxygen species was 50 times lower in air-adapted cells versus control cells, suggesting enhanced anti-oxidant mechanisms that attenuated the O2 toxicity. In this regard, (i the transcripts and activities of superoxide dismutase, catalase and peroxidase significantly increased; and (ii the thiol-molecules (cysteine + coenzyme M-SH + sulfide and polyphosphate contents were respectively 2 and 5 times higher in air-adapted cells versus anaerobic-control cells. Long-term cultures (18 days of air-adapted cells exposed to 2% O2 exhibited the ability to form biofilms. These data indicate that M. acetivorans develops multiple mechanisms to contend with O2 and the associated oxidative stress, as also suggested by genome analyses for some methanogens.

  2. Singlet Oxygen Production by Illuminated Road Dust and Winter Street Sweepings

    Science.gov (United States)

    Schneider, S.; Gan, L.; Gao, S.; Hoy, K. S.; Kwasny, J. R.; Styler, S. A.

    2017-12-01

    Road dust is an important urban source of primary particulate matter, especially in cities where sand and other traction materials are applied to roadways in winter. Although the composition and detrimental health effects of road dust are reasonably well characterized, little is currently known regarding its chemical behaviour. Motivated by our previous work, in which we showed that road dust is a photochemical source of singlet oxygen (1O2), we investigated 1O2 production by bulk winter street sweepings and by road dust collected in a variety of urban, industrial, and suburban locations in both autumn and spring. In all cases, the production of 1O2 by road dust was greater than that by Arizona test dust and desert-sourced dust, which highlights the unique photochemical environment afforded by this substrate. Mechanistically, we observed correlations between 1O2 production and the UV absorbance properties of dust extracts, which suggests the involvement of chromophoric dissolved organic matter in the observed photochemistry. Taken together, this work provides evidence that road dust-mediated photochemistry may influence the environmental lifetime of pollutants that react via 1O2-mediated pathways, including polycyclic aromatic hydrocarbons.

  3. Nicorandil prevents sirolimus-induced production of reactive oxygen species, endothelial dysfunction, and thrombus formation

    Directory of Open Access Journals (Sweden)

    Ken Aizawa

    2015-03-01

    Full Text Available Sirolimus (SRL is widely used to prevent restenosis after percutaneous coronary intervention. However, its beneficial effect is hampered by complications of thrombosis. Several studies imply that reactive oxygen species (ROS play a critical role in endothelial dysfunction and thrombus formation. The present study investigated the protective effect of nicorandil (NIC, an anti-angina agent, on SRL-associated thrombosis. In human coronary artery endothelial cells (HCAECs, SRL stimulated ROS production, which was prevented by co-treatment with NIC. The preventive effect of NIC on ROS was abolished by 5-hydroxydecanoate but not by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. NIC also inhibited SRL-induced up-regulation of NADPH oxidase subunit p22phox mRNA. Co-treatment with NIC and SRL significantly up-regulated superoxide dismutase 2. NIC treatment significantly improved SRL-induced decrease in viability of HCAECs. The functional relevance of the preventive effects of NIC on SRL-induced ROS production and impairment of endothelial viability was investigated in a mouse model of thrombosis. Pretreatment with NIC inhibited the SRL-induced acceleration of FeCl3-initiated thrombus formation and ROS production in the testicular arteries of mice. In conclusion, NIC prevented SRL-induced thrombus formation, presumably due to the reduction of ROS and to endothelial protection. The therapeutic efficacy of NIC could represent an additional option in the prevention of SRL-related thrombosis.

  4. Heat Pipe Solar Receiver for Oxygen Production of Lunar Regolith, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Researchers have determined that lunar soil contains approximately 43% oxygen in the lunar soil oxides, which could be extracted to provide breathable oxygen for...

  5. Effect of magnesium on reactive oxygen species production in the thigh muscles of broiler chickens.

    Science.gov (United States)

    Liu, Y X; Guo, Y M; Wang, Z

    2007-02-01

    1. The objective of the present study was to investigate the effect of magnesium (Mg) on reactive oxygen species (ROS) production in the thigh muscles of broiler chickens. A total of 96 1-d-old male Arbor Acre broiler chickens were randomly allocated into two groups, fed either on low-Mg or control diets containing about 1.2 g/kg or 2.4 g Mg/kg dry matter. 2. The low-Mg diet significantly increased malondialdehyde (MDA) concentration and decreased glutathione (GSH) in the thigh muscles of broiler chickens. ROS production in the thigh muscle homogenate was significantly higher in the low-Mg group than in the control group. Compared with the control, muscle Mg concentration of broiler chickens from the low-Mg group decreased by 9.5%. 3. Complex II and III activities of the mitochondrial electron transport chain in broilers on low-Mg diet increased by 23 and 35%, respectively. Significant negative correlations between ROS production and the activities of mitochondrial electron transport chain (ETC) complexes were observed. 4. The low-Mg diet did not influence contents of iron (Fe) or calcium (Ca) in the thigh muscles of broiler chickens and did not influence unsaturated fatty acid composition (except C18:2) in the thigh muscles. 5. A low-Mg diet decreased Mg concentration in the thigh muscles of broiler chickens and then induced higher activities of mitochondrial ETC, consequently increasing ROS production. These results suggest that Mg modulates the oxidation-anti-oxidation system of the thigh muscles at least partly through affecting ROS production.

  6. The relation between in vivo ethylene production and oxygen partial pressure

    NARCIS (Netherlands)

    Sanders, M.G.; Wild, de H.P.J.

    2003-01-01

    Modelling in vivo ethylene production rate in relation to O2 partial pressure was used to improve understanding of enzyme kinetics of 1-aminocyclopropane-1-carboxylate oxidase (ACC oxidase). Tomato fruit were stored in an extensive range of O2 partial pressures at 8, 13 and 18 °C. Ethylene

  7. Biomass characterization by dielectric monitoring of viability and oxygen uptake rate measurements in a novel membrane bioreactor.

    Science.gov (United States)

    Shariati, Farshid Pajoum; Heran, Marc; Sarrafzadeh, Mohammad Hossein; Mehrnia, Mohammad Reza; Sarzana, Gabriele; Ghommidh, Charles; Grasmick, Alain

    2013-07-01

    The application of permittivity and oxygen uptake rate (OUR) as biological process control parameters in a wastewater treatment system was evaluated. Experiments were carried out in a novel airlift oxidation ditch membrane bioreactor under different organic loading rates (OLR). Permittivity as representative of activated sludge viability was measured by a capacitive on-line sensor. OUR was also measured as a representative for respirometric activity. Results showed that the biomass concentration increases with OLR and all biomass related measurements and simulators such as MLSS, permittivity, OUR, ASM1 and ASM3 almost follow the same increasing trends. The viability of biomass decreased when the OLR was reduced from 5 to 4 kg COD m(-3)d(-1). During decreasing of OLR, biomass related parameters generally decreased but not in a similar manner. Also, protein concentration in the system during OLR decreasing changed inversely with the activated sludge viability. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Estimation of Viable Biomass In Wastewater And Activated Sludge By Determination of ATP, Oxygen Utilization Rate And FDA Hydrolysis

    DEFF Research Database (Denmark)

    Jørgensen, Poul-Erik; Eriksen, T.; Jensen, B.K.

    1992-01-01

    ATP content, oxygen utilization rate (OUR) and fluorescein diacetate (FDA) hydrolysis were tested for the ability to express the amount of viable biomass in wastewater and activated sludge. The relationship between biomass and these activity parameters was established in growth cultures made...... with biomass, while FDA hydrolysis in the sludge failed to show any such correlation. Conversion factors of 3 mg ATP/g dw, 300 mg O2/h g dw and 0.4 A/h (mg dw/ml) for ATP, OUR and FDA methods, respectively, were calculated. When the methods were applied for in situ determinations in four different wastewater...... plants, it was found that ATP content and respiration rate estimated viable biomass to range from 81 to 293 mg dw/g SS for raw wastewater and from 67 to 187 mg dw/g SS for activated sludge with a rather weak correlation between ATP and respiration measurements. The FDA hydrolysis estimated viable biomass...

  9. Denitrification rates and excess nitrogen gas concentrations in the Arabian Sea oxygen deficient zone

    Digital Repository Service at National Institute of Oceanography (India)

    Devol, A; Uhlenhopp, A; Naqvi, S.W.A; Brandes, J.A; Jayakumar, D.A; Naik, H.; Gaurin, S.; Codispoti, L.A.; Yoshinari, T.

    Rates of canonical, i.e. heterotrophic, water-column denitrification were measured by sup(15)N incubation techniques at a number of coastal and open ocean stations in the Arabian Sea. Measurements of N2 :Ar gas ratios were also made to obtain...

  10. Memory behaviors of entropy production rates in heat conduction

    Science.gov (United States)

    Li, Shu-Nan; Cao, Bing-Yang

    2018-02-01

    Based on the relaxation time approximation and first-order expansion, memory behaviors in heat conduction are found between the macroscopic and Boltzmann-Gibbs-Shannon (BGS) entropy production rates with exponentially decaying memory kernels. In the frameworks of classical irreversible thermodynamics (CIT) and BGS statistical mechanics, the memory dependency on the integrated history is unidirectional, while for the extended irreversible thermodynamics (EIT) and BGS entropy production rates, the memory dependences are bidirectional and coexist with the linear terms. When macroscopic and microscopic relaxation times satisfy a specific relationship, the entropic memory dependences will be eliminated. There also exist initial effects in entropic memory behaviors, which decay exponentially. The second-order term are also discussed, which can be understood as the global non-equilibrium degree. The effects of the second-order term are consisted of three parts: memory dependency, initial value and linear term. The corresponding memory kernels are still exponential and the initial effects of the global non-equilibrium degree also decay exponentially.

  11. Oxygen production by molten alkali metal salts using multiple absorption-desorption cycles

    Science.gov (United States)

    Cassano, Anthony A.

    1985-01-01

    A continuous chemical air separation is performed wherein oxygen is recovered with a molten alkali metal salt oxygen acceptor in a series of absorption zones which are connected to a plurality of desorption zones operated in separate parallel cycles with the absorption zones. A greater recovery of high pressure oxygen is achieved at reduced power requirements and capital costs.

  12. Oxygen production by molten alkali metal salts using multiple absorption-desorption cycles

    Science.gov (United States)

    Cassano, A.A.

    1985-07-02

    A continuous chemical air separation is performed wherein oxygen is recovered with a molten alkali metal salt oxygen acceptor in a series of absorption zones which are connected to a plurality of desorption zones operated in separate parallel cycles with the absorption zones. A greater recovery of high pressure oxygen is achieved at reduced power requirements and capital costs. 3 figs.

  13. Buyer-vendor coordination for fixed lifetime product with quantity discount under finite production rate

    Science.gov (United States)

    Zhang, Qinghong; Luo, Jianwen; Duan, Yongrui

    2016-03-01

    Buyer-vendor coordination has been widely addressed; however, the fixed lifetime of the product is seldom considered. In this paper, we study the coordination of an integrated production-inventory system with quantity discount for a fixed lifetime product under finite production rate and deterministic demand. We first derive the buyer's ordering policy and the vendor's production batch size in decentralised and centralised systems. We then compare the two systems and show the non-coordination of the ordering policies and the production batch sizes. To improve the supply chain efficiency, we propose quantity discount contract and prove that the contract can coordinate the buyer-vendor supply chain. Finally, we present analytically tractable solutions and give a numerical example to illustrate the benefits of the proposed quantity discount strategy.

  14. Tailoring nanomaterial products through electrode material and oxygen partial pressure in a mini-arc plasma reactor

    International Nuclear Information System (INIS)

    Cui Shumao; Mattson, Eric C.; Lu, Ganhua; Hirschmugl, Carol; Gajdardziska-Josifovska, Marija; Chen Junhong

    2012-01-01

    Nanomaterials with controllable morphology and composition are synthesized by a simple one-step vapor condensation process using a mini-arc plasma source. Through systematic investigation of mini-arc reactor parameters, the roles of carrier gas, electrode material, and precursor on producing diverse nanomaterial products are revealed. Desired nanomaterial products, including tungsten oxide nanoparticles (NPs), tungsten oxide nanorods (NRs), tungsten oxide and tin oxide NP mixtures and pure tin dioxide NPs can thus be obtained by tailoring reaction conditions. The amount of oxygen in the reactor is critical to determining the final nanomaterial product. Without any precursor material present, a lower level of oxygen in the reactor favors the production of W 18 O 49 NRs with tungsten as cathode, while a high level of oxygen produces more round WO 3 NPs. With the presence of a precursor material, amorphous particles are favored with a high ratio of argon:oxygen. Oxygen is also found to affect tin oxide crystallization from its amorphous phase in the thermal annealing. Results from this study can be used for guiding gas phase nanomaterial synthesis in the future.

  15. Induction of Apoptosis in Human Multiple Myeloma Cell Lines by Ebselen via Enhancing the Endogenous Reactive Oxygen Species Production

    Directory of Open Access Journals (Sweden)

    Liang Zhang

    2014-01-01

    Full Text Available Ebselen a selenoorganic compound showing glutathione peroxidase like activity is an anti-inflammatory and antioxidative agent. Its cytoprotective activity has been investigated in recent years. However, experimental evidence also shows that ebselen causes cell death in several cancer cell types whose mechanism has not yet been elucidated. In this study, we examined the effect of ebselen on multiple myeloma (MM cell lines in vitro. The results showed that ebselen significantly enhanced the production of reactive oxygen species (ROS accompanied by cell viability decrease and apoptosis rate increase. Further studies revealed that ebselen can induce Bax redistribution from the cytosol to mitochondria leading to mitochondrial membrane potential ΔΨm changes and cytochrome C release from the mitochondria to cytosol. Furtherly, we found that exogenous addition of N-acetyl cysteine (NAC completely diminished the cell damage induced by ebselen. This result suggests that relatively high concentration of ebselen can induce MM cells apoptosis in culture by enhancing the production of endogenous ROS and triggering mitochondria mediated apoptotic pathway.

  16. Induction of apoptosis in human multiple myeloma cell lines by ebselen via enhancing the endogenous reactive oxygen species production.

    Science.gov (United States)

    Zhang, Liang; Zhou, Liwei; Du, Jia; Li, Mengxia; Qian, Chengyuan; Cheng, Yi; Peng, Yang; Xie, Jiayin; Wang, Dong

    2014-01-01

    Ebselen a selenoorganic compound showing glutathione peroxidase like activity is an anti-inflammatory and antioxidative agent. Its cytoprotective activity has been investigated in recent years. However, experimental evidence also shows that ebselen causes cell death in several cancer cell types whose mechanism has not yet been elucidated. In this study, we examined the effect of ebselen on multiple myeloma (MM) cell lines in vitro. The results showed that ebselen significantly enhanced the production of reactive oxygen species (ROS) accompanied by cell viability decrease and apoptosis rate increase. Further studies revealed that ebselen can induce Bax redistribution from the cytosol to mitochondria leading to mitochondrial membrane potential ΔΨm changes and cytochrome C release from the mitochondria to cytosol. Furtherly, we found that exogenous addition of N-acetyl cysteine (NAC) completely diminished the cell damage induced by ebselen. This result suggests that relatively high concentration of ebselen can induce MM cells apoptosis in culture by enhancing the production of endogenous ROS and triggering mitochondria mediated apoptotic pathway.

  17. Study and Development of a Fluorescence Based Sensor System for Monitoring Oxygen in Wine Production: The WOW Project.

    Science.gov (United States)

    Trivellin, Nicola; Barbisan, Diego; Badocco, Denis; Pastore, Paolo; Meneghesso, Gaudenzio; Meneghini, Matteo; Zanoni, Enrico; Belgioioso, Giuseppe; Cenedese, Angelo

    2018-04-07

    The importance of oxygen in the winemaking process is widely known, as it affects the chemical aspects and therefore the organoleptic characteristics of the final product. Hence, it is evident the usefulness of a continuous and real-time measurements of the levels of oxygen in the various stages of the winemaking process, both for monitoring and for control. The WOW project (Deployment of WSAN technology for monitoring Oxygen in Wine products) has focused on the design and the development of an innovative device for monitoring the oxygen levels in wine. This system is based on the use of an optical fiber to measure the luminescent lifetime variation of a reference metal/porphyrin complex, which decays in presence of oxygen. The developed technology results in a high sensitivity and low cost sensor head that can be employed for measuring the dissolved oxygen levels at several points inside a wine fermentation or aging tank. This system can be complemented with dynamic modeling techniques to provide predictive behavior of the nutrient evolution in space and time given few sampled measuring points, for both process monitoring and control purposes. The experimental validation of the technology has been first performed in a controlled laboratory setup to attain calibration and study sensitivity with respect to different photo-luminescent compounds and alcoholic or non-alcoholic solutions, and then in an actual case study during a measurement campaign at a renown Italian winery.

  18. Study and Development of a Fluorescence Based Sensor System for Monitoring Oxygen in Wine Production: The WOW Project

    Science.gov (United States)

    Trivellin, Nicola; Barbisan, Diego; Badocco, Denis; Pastore, Paolo; Meneghini, Matteo; Zanoni, Enrico; Belgioioso, Giuseppe

    2018-01-01

    The importance of oxygen in the winemaking process is widely known, as it affects the chemical aspects and therefore the organoleptic characteristics of the final product. Hence, it is evident the usefulness of a continuous and real-time measurements of the levels of oxygen in the various stages of the winemaking process, both for monitoring and for control. The WOW project (Deployment of WSAN technology for monitoring Oxygen in Wine products) has focused on the design and the development of an innovative device for monitoring the oxygen levels in wine. This system is based on the use of an optical fiber to measure the luminescent lifetime variation of a reference metal/porphyrin complex, which decays in presence of oxygen. The developed technology results in a high sensitivity and low cost sensor head that can be employed for measuring the dissolved oxygen levels at several points inside a wine fermentation or aging tank. This system can be complemented with dynamic modeling techniques to provide predictive behavior of the nutrient evolution in space and time given few sampled measuring points, for both process monitoring and control purposes. The experimental validation of the technology has been first performed in a controlled laboratory setup to attain calibration and study sensitivity with respect to different photo-luminescent compounds and alcoholic or non-alcoholic solutions, and then in an actual case study during a measurement campaign at a renown Italian winery. PMID:29642468

  19. Vascular smooth muscle modulates endothelial control of vasoreactivity via reactive oxygen species production through myoendothelial communications.

    Directory of Open Access Journals (Sweden)

    Marie Billaud

    Full Text Available BACKGROUND: Endothelial control of vascular smooth muscle plays a major role in the resulting vasoreactivity implicated in physiological or pathological circulatory processes. However, a comprehensive understanding of endothelial (EC/smooth muscle cells (SMC crosstalk is far from complete. Here, we have examined the role of gap junctions and reactive oxygen species (ROS in this crosstalk and we demonstrate an active contribution of SMC to endothelial control of vasomotor tone. METHODOLOGY/PRINCIPAL FINDINGS: In small intrapulmonary arteries, quantitative RT-PCR, Western Blot analyses and immunofluorescent labeling evidenced connexin (Cx 37, 40 and 43 in EC and/or SMC. Functional experiments showed that the Cx-mimetic peptide targeted against Cx 37 and Cx 43 ((37,43Gap27 (1 reduced contractile and calcium responses to serotonin (5-HT simultaneously recorded in pulmonary arteries and (2 abolished the diffusion in SMC of carboxyfluorescein-AM loaded in EC. Similarly, contractile and calcium responses to 5-HT were decreased by superoxide dismutase and catalase which, catabolise superoxide anion and H(2O(2, respectively. Both Cx- and ROS-mediated effects on the responses to 5-HT were reversed by L-NAME, a NO synthase inhibitor or endothelium removal. Electronic paramagnetic resonance directly demonstrated that 5-HT-induced superoxide anion production originated from the SMC. Finally, whereas 5-HT increased NO production, it also decreased cyclic GMP content in isolated intact arteries. CONCLUSIONS/SIGNIFICANCE: These data demonstrate that agonist-induced ROS production in SMC targeting EC via myoendothelial gap junctions reduces endothelial NO-dependent control of pulmonary vasoreactivity. Such SMC modulation of endothelial control may represent a signaling pathway controlling vasoreactivity under not only physiological but also pathological conditions that often implicate excessive ROS production.

  20. Measurements of the potential ozone production rate in a forest

    Science.gov (United States)

    Crilley, L.; Sklaveniti, S.; Kramer, L.; Bloss, W.; Flynn, J. H., III; Alvarez, S. L.; Erickson, M.; Dusanter, S.; Locoge, N.; Stevens, P. S.; Millet, D. B.; Alwe, H. D.

    2017-12-01

    Biogenic volatile organic compounds (BVOC) are a significant source of organic compounds globally and alongside NOx play a key role in the formation of ozone in the troposphere. Understanding how changes in NOx concentrations feed through to altered ozone production in BVOC dominated environments will aid our understanding of future atmospheric composition, notably as developing nations transition from NOx dominated to NOx limited chemistry as a result of mitigation strategies. Here we empirically investigate this ambient ozone formation potential. We report deployment of a custom built instrument to measure in near real time the potential for in situ chemical ozone production, using an artificial light source. Our results are thus indicative of the ozone formation potential for a sampled ambient air mixture, including full VOC complexity, i.e. independent of characterization of individual organic compounds. Ground level measurements were performed as part of the PROPHET-AMOS 2016 field campaign, at a site located within a Northern Michigan forest that has typically low NOx abundance, but high isoprene and terpenoid loadings. As the ambient NOx concentrations were low during the campaign, experiments were performed in which NO was artificially added to the sampled ambient air mixture, to quantify changes in the potential ozone production rate as a function of NOx, and hence the ozone forming characteristics of the ambient air. Preliminarily results from these experiments are presented, and indicate that while ozone production increases with added NO, significant variation was observed for a given NO addition, reflecting differences in the ambient VOC chemical reactivity and ozone formation tendency.

  1. 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

  2. Sintering of porous silver compacts at controlled heating rates in oxygen or argon

    International Nuclear Information System (INIS)

    Oliber, E.A; Cugno, C; Moreno, M; Esquivel, M; Haberkon, N; Fiscina, J.E; Gonzalez Oliver, C.J.R

    2002-01-01

    A submicronic (- 0.4μm grain size) spherical silver powder was mixed with 2wt% PVB and pressed into pellets (body A) of relative density (ρr) close to 0.54. The pellets were given a heat treatment at 235 o C for 4 hours (body B) in static air, after which the ρr values were increased by ∼2%. The preheated pellets (B) were densified in a vertical differential dilatometer, fitted with a silica head, at heating rates (hr) of 2, 4 and 10 o C min -1 under Ar or O 2 pure atmospheres. The total lineal densification [Δl(T)/lo, ΔI=Io-1(T) instantaneous thickness and lo: the initial thickness of the pellet] of the Ag-skeletons (B, of similar starting porosity) varied significantly upon changing either the (hr) or the atmosphere. It ranged from 8 to 12% giving still porous bodies of ρr∼0.80. After a small densification (stage (i)) each curve showed a clear Ti ( o C ) at which the densification (AD(T) exhibited a rapid increase (jump; stage (ii), and had a characteristic peak in densification rate (DR(T)). Then the AD continued by another mechanism (stage (iii)), related to grain growth, till the densification rate started to decrease probably due to densification (stage (iv)) of closed pores located at 4-grain corners. For every atmosphere the Ti increased with heating rate, and the Ti values for O 2 were 79- 105 o C lower than those for Ar. From DR kinetics analysis it is concluded that under O 2 stage (ii) is due to grain boundary diffusivity (gb) whereas for stage (iii) the volume (vol) diffusion is the main process. From detail densification fits it is shown for stage (iii) there is an initial contribution to densification coming up from an initial stage controlled by (gb) diffusion, and that the main process is still the intermediate stage with simultaneous grain growth controlled by volume self-diffusivity. For the Ar case the whole densification range appears to be controlled by (gb) diffusivity. Some impurity contamination of the Ag could produce a (gb

  3. Effects of structure and oxygen flow rate on the photo-response of amorphous IGZO-based photodetector devices

    Science.gov (United States)

    Jang, Jun Tae; Ko, Daehyun; Choi, Sungju; Kang, Hara; Kim, Jae-Young; Yu, Hye Ri; Ahn, Geumho; Jung, Haesun; Rhee, Jihyun; Lee, Heesung; Choi, Sung-Jin; Kim, Dong Myong; Kim, Dae Hwan

    2018-02-01

    In this study, we investigated how the structure and oxygen flow rate (OFR) during the sputter-deposition affects the photo-responses of amorphous indium-gallium-zinc-oxide (a-IGZO)-based photodetector devices. As the result of comparing three types of device structures with one another, which are a global Schottky diode, local Schottky diode, and thin-film transistor (TFT), the IGZO TFT with the gate pulse technique suppressing the persistent photoconductivity (PPC) is the most promising photodetector in terms of a high photo-sensitivity and uniform sensing characteristic. In order to analyze the IGZO TFT-based photodetectors more quantitatively, the time-evolution of sub-gap density-of-states (DOS) was directly observed under photo-illumination and consecutively during the PPC-compensating period with applying the gate pulse. It shows that the increased ionized oxygen vacancy (VO2+) defects under photo-illumination was fully recovered by the positive gate pulse and even overcompensated by additional electron trapping. Based on experimentally extracted sub-gap DOS, the origin on PPC was successfully decomposed into the hole trapping and the VO ionization. Although the VO ionization is enhanced in lower OFR (O-poor) device, the PPC becomes more severe in high OFR (O-rich) device because the hole trapping dominates the PPC in IGZO TFT under photo-illumination rather than the VO ionization and more abundant holes are trapped into gate insulator and/or interface in O-rich TFTs. Similarly, the electron trapping during the PPC-compensating period with applying the positive gate pulse becomes more prominent in O-rich TFTs. It is attributed to more hole/electron traps in the gate insulator and/or interface, which is associated with oxygen interstitials, or originates from the ion bombardment-related lower quality gate oxide in O-rich devices.

  4. Sulfur Isotope Trends in Archean Microbialite Facies Record Early Oxygen Production and Consumption

    Science.gov (United States)

    Zerkle, A.; Meyer, N.; Izon, G.; Poulton, S.; Farquhar, J.; Claire, M.

    2014-12-01

    The major and minor sulfur isotope composition (δ34S and Δ33S) of pyrites preserved in ~2.65-2.5 billion-year-old (Ga) microbialites record localized oxygen production and consumption near the mat surface. These trends are preserved in two separate drill cores (GKF01 and BH1-Sacha) transecting the Campbellrand-Malmani carbonate platform (Ghaap Group, Transvaal Supergroup, South Africa; Zerkle et al., 2012; Izon et al., in review). Microbialite pyrites possess positive Δ33S values, plotting parallel to typical Archean trends (with a Δ33S/δ34S slope of ~0.9) but enriched in 34S by ~3 to 7‰. We propose that these 34S-enriched pyrites were formed from a residual pool of sulfide that was partially oxidized via molecular oxygen produced by surface mat-dwelling cyanobacteria. Sulfide, carrying the range of Archean Δ33S values, could have been produced deeper within the microbial mat by the reduction of sulfate and elemental sulfur, then fractionated upon reaction with O2 produced by oxygenic photosynthesis. Preservation of this positive 34S offset requires that: 1) sulfide was only partially (50­­-80%) consumed by oxidation, meaning H2S was locally more abundant (or more rapidly produced) than O2, and 2) the majority of the sulfate produced via oxidation was not immediately reduced to sulfide, implying either that the sulfate pool was much larger than the sulfide pool, or that the sulfate formed near the mat surface was transported and reduced in another part of the system. Contrastingly, older microbialite facies (> 2.7 Ga; Thomazo et al., 2013) appear to lack these observed 34S enrichments. Consequently, the onset of 34S enrichments could mark a shift in mat ecology, from communities dominated by anoxygenic photosynthesizers to cyanobacteria. Here, we test these hypotheses with new spatially resolved mm-scale trends in sulfur isotope measurements from pyritized stromatolites of the Vryburg Formation, sampled in the lower part of the BH1-Sacha core. Millimeter

  5. The radiolysis of uracil in oxygenated aqueous solutions. A study by product analysis and pulse radiolysis

    International Nuclear Information System (INIS)

    Schuchnmann, M.N.; Sonntag, C. von

    1983-01-01

    Hydroxyl radicals are generated by the radiolysis of N 2 O-O 2 (4:1 v/v)-saturated aqueous solutions of uracil. They add to the 5,6-double bond of the substrate. These radicals are converted by oxygen into the corresponding peroxyl radicals (I) and (II), respectively. Peroxyl radical (I) undergoes a base-induced O 2 - elimination. As an intermediate 5-hydroxyisopyrimidine is formed which rearranges into isobarbituric acid and adds water forming 5,6-dihydro-5,6-dihydroxyuracil. Competing with this base-induced reaction of radical (I) there is a bimolecular decay of radicals (I) and (II). These processes become predominant at low pH. For this reason a strong pH dependence of G (products) is observed. The major products are (G values at pH 3 and 10 in parentheses) 5,6-dihydroxy-5,6-dihydrouracil (1.1; 2.4), isobarbituric acid (0; 1.2), N-formyl-5-hydroxyhydantoin (1.6; 0.2), 5-hydroxybarbituric acid (0.9; 0.2). 5-Hydroxybarbituric acid is formed in its keto form. Its deprotonation has been followed by pulse conductometry. Details of the reaction mechanism, e.g. the involvement of oxyl radicals in the bimolecular decay of (I) and (II), are discussed. (author)

  6. Sibutramine provokes apoptosis of aortic endothelial cells through altered production of reactive oxygen and nitrogen species.

    Science.gov (United States)

    Morikawa, Yoshifumi; Shibata, Akinobu; Okumura, Naoko; Ikari, Akira; Sasajima, Yasuhide; Suenami, Koichi; Sato, Kiyohito; Takekoshi, Yuji; El-Kabbani, Ossama; Matsunaga, Toshiyuki

    2017-01-01

    Overdose administration of sibutramine, a serotonin-noradrenalin reuptake inhibitor, is considered to elicit severe side effects including hypertension, whose pathogenic mechanism remains unclear. Here, we found that 48-h incubation with >10μM sibutramine provokes apoptosis of human aortic endothelial (HAE) cells. Treatment with the lethal concentration of sibutramine facilitated production of reactive oxygen species (ROS), altered expression of endoplasmic reticulum stress response genes (heat shock protein 70 and C/EBP homologous protein), and inactivated 26S proteasome-based proteolysis. The treatment also decreased cellular level of nitric oxide (NO) through lowering of expression and activity of endothelial NO synthase. These results suggest that ROS production and depletion of NO are crucial events in the apoptotic mechanism and may be linked to the pathogenesis of vasoconstriction elicited by the drug. Compared to sibutramine, its metabolites (N-desmethylsibutramine and N-didesmethylsibutramine) were much less cytotoxic to HAE cells, which hardly metabolized sibutramine. In contrast, both the drug and metabolites showed low cytotoxicity to hepatic HepG2 cells with high metabolic potency and expression of cytochrome P450 (CYP) 3A4. The cytotoxicity of sibutramine to HepG2 and Chang Liver cells was remarkably augmented by inhibition and knockdown of CYP3A4. This study also suggests an inverse relationship between sibutramine cytotoxicity and CYP3A4-mediated metabolism into the N-desmethyl metabolites. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Heart Rate and Oxygen Saturation Change Patterns During 6-min Walk Test in Subjects With Chronic Thromboembolic Pulmonary Hypertension.

    Science.gov (United States)

    Inagaki, Takeshi; Terada, Jiro; Yahaba, Misuzu; Kawata, Naoko; Jujo, Takayuki; Nagashima, Kengo; Sakao, Seiichiro; Tanabe, Nobuhiro; Tatsumi, Koichiro

    2017-12-26

    The 6-min walk test (6MWT) is commonly performed to assess functional status in patients with chronic thromboembolic pulmonary hypertension. However, changes in heart rate and oxygen saturation ( S pO 2 ) patterns during 6MWT in patients with chronic thromboembolic pulmonary hypertension remain unclear. Thirty-one subjects with chronic thromboembolic pulmonary hypertension were retrospectively evaluated to examine the relationships between the change in heart rate (Δheart rate), heart rate acceleration time, slope of heart rate acceleration, heart rate recovery during the first minute after 6MWT (HRR1), change in S pO 2 (Δ S pO 2 ), S pO 2 reduction time, and S pO 2 recovery time during 6MWT, and the severity of pulmonary hemodynamics assessed by right heart catheterization and echocardiography. Subjects with severe chronic thromboembolic pulmonary hypertension had significantly longer heart rate acceleration time (144.9 ± 63.9 s vs 96.0 ± 42.5 s, P = .033), lower Δheart rate (47.4 ± 16.9 vs 61.8 ± 13.6 beats, P = .02), and lower HRR1 (13.3 ± 9.0 beats vs 27.1 ± 9.2 beats, P pulmonary hypertension. Subjects with severe chronic thromboembolic pulmonary hypertension also had significantly longer S pO 2 reduction time (178.3 ± 70.3 s vs 134.3 ± 58.4 s, P = .03) and S pO 2 recovery time (107.6 ± 35.3 s vs 69.8 ± 32.7 s, P = .004) than did subjects with mild chronic thromboembolic pulmonary hypertension. Multivariate linear regression analysis showed only mean pulmonary arterial pressure independently was associated with heart rate acceleration time and slope of heart rate acceleration. Heart rate and S pO 2 change patterns during 6MWT is predominantly associated with pulmonary hemodynamics in subjects with chronic thromboembolic pulmonary hypertension. Evaluating heart rate and S pO 2 change patterns during 6MWT may serve a safe and convenient way to follow the change in pulmonary hemodynamics. Copyright © 2017 by Daedalus Enterprises.

  8. The change of longitudinal relaxation rate in oxygen enhanced pulmonary MRI depends on age and BMI but not diffusing capacity of carbon monoxide in healthy never-smokers.

    Directory of Open Access Journals (Sweden)

    Simon Sven Ivan Kindvall

    Full Text Available Oxygen enhanced pulmonary MRI is a promising modality for functional lung studies and has been applied to a wide range of pulmonary conditions. The purpose of this study was to characterize the oxygen enhancement effect in the lungs of healthy, never-smokers, in light of a previously established relationship between oxygen enhancement and diffusing capacity of carbon monoxide in the lung (DL,CO in patients with lung disease.In 30 healthy never-smoking volunteers, an inversion recovery with gradient echo read-out (Snapshot-FLASH was used to quantify the difference in longitudinal relaxation rate, while breathing air and 100% oxygen, ΔR1, at 1.5 Tesla. Measurements were performed under multiple tidal inspiration breath-holds.In single parameter linear models, ΔR1 exhibit a significant correlation with age (p = 0.003 and BMI (p = 0.0004, but not DL,CO (p = 0.33. Stepwise linear regression of ΔR1 yields an optimized model including an age-BMI interaction term.In this healthy, never-smoking cohort, age and BMI are both predictors of the change in MRI longitudinal relaxation rate when breathing oxygen. However, DL,CO does not show a significant correlation with the oxygen enhancement. This is possibly because oxygen transfer in the lung is not diffusion limited at rest in healthy individuals. This work stresses the importance of using a physiological model to understand results from oxygen enhanced MRI.

  9. Cadmium accumulation in and tolerance of rice (Oryza sativa L.) varieties with different rates of radial oxygen loss.

    Science.gov (United States)

    Wang, M Y; Chen, A K; Wong, M H; Qiu, R L; Cheng, H; Ye, Z H

    2011-06-01

    Cadmium (Cd) uptake and tolerance were investigated among 20 rice cultivars based on a field experiment (1.2 mg Cd kg⁻¹ in soil) and a soil pot trial (control, 100 mg Cd kg⁻¹), and rates of radial oxygen loss (ROL) were measured under a deoxygenated solution. Significant differences were found among the cultivars in: (1) brown rice Cd concentrations (0.11-0.29 mg kg⁻¹) in a field soil, (2) grain Cd tolerance (34-113%) and concentrations (2.1-6.5 mg kg⁻¹) in a pot trial, and (3) rates of ROL (15-31 mmol O₂ kg⁻¹ root d.w. h⁻¹). Target hazard quotients were calculated for the field experiment to assess potential Cd risk. Significant negative relationships were found between rates of ROL and concentrations of Cd in brown rice or straw under field and greenhouse conditions, indicating that rice cultivars with higher rates of ROL had higher capacities for limiting the transfer of Cd to rice and straw. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. A COMPARISON BETWEEN VENTILATION AND HEART RATE AS INDICATOR OF OXYGEN UPTAKE DURING DIFFERENT INTENSITIES OF EXERCISE

    Directory of Open Access Journals (Sweden)

    Jacques Prioux

    2010-03-01

    Full Text Available The aim of this study is to compare the relation between ventilation (VE and oxygen uptake (VO2 [VO2=ƒ(VE] and between heart rate (HR and VO2 [VO2=ƒ(HR]. Each one of the subjects performed three types of activities of different intensities (walking without load, walking with load and intermittent work. VO2, VE, and HR were measured continuously by using indirect calorimetry and an electrocardiogram. Linear regressions and coefficients of determination (r² were calculated to compare the relation VO2 =ƒ(VE and VO2 =ƒ(HR for two different regroupings: by session duration (r²session and by subject (r²subject. Results showed that r²session of the relation VO2 =ƒ(VE were significantly higher than those of the relation VO2 =ƒ(HR for steady state activities (walking with or without load during 3 or 6 min, p < 0.01 and for activities without oxygen consumption steady state (walking with or without load during 1 min, p < 0.01 and intermittent work, p < 0.05. VE is more strongly correlated with VO2 than with HR. This is a very promising approach to develop a new method to estimate energy expenditure

  11. Oxygen-Vacancy Abundant Ultrafine Co3O4/Graphene Composites for High-Rate Supercapacitor Electrodes.

    Science.gov (United States)

    Yang, Shuhua; Liu, Yuanyue; Hao, Yufeng; Yang, Xiaopeng; Goddard, William A; Zhang, Xiao Li; Cao, Bingqiang

    2018-04-01

    The metal oxides/graphene composites are one of the most promising supercapacitors (SCs) electrode materials. However, rational synthesis of such electrode materials with controllable conductivity and electrochemical activity is the topical challenge for high-performance SCs. Here, the Co 3 O 4 /graphene composite is taken as a typical example and develops a novel/universal one-step laser irradiation method that overcomes all these challenges and obtains the oxygen-vacancy abundant ultrafine Co 3 O 4 nanoparticles/graphene (UCNG) composites with high SCs performance. First-principles calculations show that the surface oxygen vacancies can facilitate the electrochemical charge transfer by creating midgap electronic states. The specific capacitance of the UCNG electrode reaches 978.1 F g -1 (135.8 mA h g -1 ) at the current densities of 1 A g -1 and retains a high capacitance retention of 916.5 F g -1 (127.3 mA h g -1 ) even at current density up to 10 A g -1 , showing remarkable rate capability (more than 93.7% capacitance retention). Additionally, 99.3% of the initial capacitance is maintained after consecutive 20 000 cycles, demonstrating enhanced cycling stability. Moreover, this proposed laser-assisted growth strategy is demonstrated to be universal for other metal oxide/graphene composites with tuned electrical conductivity and electrochemical activity.

  12. A comparison of measured radionuclide release rates from Three Mile Island Unit-2 core debris for different oxygen chemical potentials

    International Nuclear Information System (INIS)

    Baston, V.F.; Hofstetter, K.J.; Ryan, R.F.

    1987-01-01

    Chemical and radiochemical analyses of reactor coolant samples taken during defueling of the Three Mile Island Unit-2 (TMI-2) reactor provide relevant data to assist in understanding the solution chemistry of the radionuclides retained within the TMI-2 reactor coolant system. Hydrogen peroxide was added to various plant systems to provide disinfection for microbial contamination and has provided the opportunity to observe radionuclide release under different oxygen chemical potentials. A comparison of the radionuclide release rates with and without hydrogen peroxide has been made for these separate but related cases, i.e., the fuel transfer canal and connecting spent-fuel pool A with the TMI-2 reactor plenum in the fuel transfer canal, core debris grab sample laboratory experiments, and the reactor vessel fluid and associated core debris. Correlation and comparison of these data indicate a physical parameter dependence (surface-to-volume ratio) affecting all radionuclide release; however, selected radionuclides also demonstrate a chemical dependence release under the different oxygen chemical potentials. Chemical and radiochemical analyses of reactor coolant samples taken during defueling of the Three Mile Island Unit-2 (TMI-2) reactor provide relevant data to assist in understanding the solution chemistry of the radionuclides retained within the TMI-2 reactor coolant system

  13. Plutonium-239 production rate study using a typical fusion reactor

    International Nuclear Information System (INIS)

    Faghihi, F.; Havasi, H.; Amin-Mozafari, M.

    2008-01-01

    The purpose of the present paper is to compute fissile 239 Pu material by supposed typical fusion reactor operation to make the fuel requirement for other purposes (e.g. MOX fissile fuel, etc.). It is assumed that there is a fusion reactor has a cylindrical geometry and uses uniformly distributed deuterium-tritium as fuel so that neutron wall load is taken at 10(MW)/(m 2 ) . Moreover, the reactor core is surrounded by six suggested blankets to make best performance of the physical conditions described herein. We determined neutron flux in each considered blanket as well as tritium self-sufficiency using two groups neutron energy and then computation is followed by the MCNP-4C code. Finally, material depletion according to a set of dynamical coupled differential equations is solved to estimate 239 Pu production rate. Produced 239 Pu is compared with two typical fission reactors to find performance of plutonium breeding ratio in the case of the fusion reactor. We found that 0.92% of initial U is converted into fissile Pu by our suggested fusion reactor with thermal power of 3000 MW. For comparison, 239 Pu yield of suggested large scale PWR is about 0.65% and for LMFBR is close to 1.7%. The results show that the fusion reactor has an acceptable efficiency for Pu production compared with a large scale PWR fission reactor type

  14. Plutonium-239 production rate study using a typical fusion reactor

    Energy Technology Data Exchange (ETDEWEB)

    Faghihi, F. [Research Center for Radiation Protection, Shiraz University, Shiraz (Iran, Islamic Republic of)], E-mail: faghihif@shirazu.ac.ir; Havasi, H.; Amin-Mozafari, M. [Department of Nuclear Engineering, School of Engineering, Shiraz University, 71348-51154 Shiraz (Iran, Islamic Republic of)

    2008-05-15

    The purpose of the present paper is to compute fissile {sup 239}Pu material by supposed typical fusion reactor operation to make the fuel requirement for other purposes (e.g. MOX fissile fuel, etc.). It is assumed that there is a fusion reactor has a cylindrical geometry and uses uniformly distributed deuterium-tritium as fuel so that neutron wall load is taken at 10(MW)/(m{sup 2}) . Moreover, the reactor core is surrounded by six suggested blankets to make best performance of the physical conditions described herein. We determined neutron flux in each considered blanket as well as tritium self-sufficiency using two groups neutron energy and then computation is followed by the MCNP-4C code. Finally, material depletion according to a set of dynamical coupled differential equations is solved to estimate {sup 239}Pu production rate. Produced {sup 239}Pu is compared with two typical fission reactors to find performance of plutonium breeding ratio in the case of the fusion reactor. We found that 0.92% of initial U is converted into fissile Pu by our suggested fusion reactor with thermal power of 3000 MW. For comparison, {sup 239}Pu yield of suggested large scale PWR is about 0.65% and for LMFBR is close to 1.7%. The results show that the fusion reactor has an acceptable efficiency for Pu production compared with a large scale PWR fission reactor type.

  15. Oxygen Partial Pressure Is a Rate-Limiting Parameter for Cell Proliferation in 3D Spheroids Grown in Physioxic Culture Condition.

    Science.gov (United States)

    Gomes, Aurélie; Guillaume, Ludivine; Grimes, David Robert; Fehrenbach, Jérôme; Lobjois, Valérie; Ducommun, Bernard

    2016-01-01

    The in situ oxygen partial pressure in normal and tumor tissues is in the range of a few percent. Therefore, when studying cell growth in 3D culture systems, it is essential to consider how the physiological oxygen concentration, rather than the one in the ambient air, influences the proliferation parameters. Here, we investigated the effect of reducing oxygen partial pressure from 21% to 5% on cell proliferation rate and regionalization in a 3D tumor spheroid model. We found that 5% oxygen concentration strongly inhibited spheroid growth, changed the proliferation gradient and reduced the 50% In Depth Proliferation index (IDP50), compared with culture at 21% oxygen. We then modeled the oxygen partial pressure profiles using the experimental data generated by culturing spheroids in physioxic and normoxic conditions. Although hypoxia occurred at similar depth in spheroids grown in the two conditions, oxygen partial pressure was a major rate-limiting factor with a critical effect on cell proliferation rate and regionalization only in spheroids grown in physioxic condition and not in spheroids grown at atmospheric normoxia. Our findings strengthen the need to consider conducting experiment in physioxic conditions (i.e., tissue normoxia) for proper understanding of cancer cell biology and the evaluation of anticancer drugs in 3D culture systems.

  16. The mechanics of granitoid systems and maximum entropy production rates.

    Science.gov (United States)

    Hobbs, Bruce E; Ord, Alison

    2010-01-13

    A model for the formation of granitoid systems is developed involving melt production spatially below a rising isotherm that defines melt initiation. Production of the melt volumes necessary to form granitoid complexes within 10(4)-10(7) years demands control of the isotherm velocity by melt advection. This velocity is one control on the melt flux generated spatially just above the melt isotherm, which is the control valve for the behaviour of the complete granitoid system. Melt transport occurs in conduits initiated as sheets or tubes comprising melt inclusions arising from Gurson-Tvergaard constitutive behaviour. Such conduits appear as leucosomes parallel to lineations and foliations, and ductile and brittle dykes. The melt flux generated at the melt isotherm controls the position of the melt solidus isotherm and hence the physical height of the Transport/Emplacement Zone. A conduit width-selection process, driven by changes in melt viscosity and constitutive behaviour, operates within the Transport Zone to progressively increase the width of apertures upwards. Melt can also be driven horizontally by gradients in topography; these horizontal fluxes can be similar in magnitude to vertical fluxes. Fluxes induced by deformation can compete with both buoyancy and topographic-driven flow over all length scales and results locally in transient 'ponds' of melt. Pluton emplacement is controlled by the transition in constitutive behaviour of the melt/magma from elastic-viscous at high temperatures to elastic-plastic-viscous approaching the melt solidus enabling finite thickness plutons to develop. The system involves coupled feedback processes that grow at the expense of heat supplied to the system and compete with melt advection. The result is that limits are placed on the size and time scale of the system. Optimal characteristics of the system coincide with a state of maximum entropy production rate. This journal is © 2010 The Royal Society

  17. Influence of residual elements in lead on oxygen- and hydrogen-gassing rates of lead-acid batteries

    Science.gov (United States)

    Lam, L. T.; Ceylan, H.; Haigh, N. P.; Lwin, T.; Rand, D. A. J.

    Raw lead materials contain many residual elements. With respect to setting 'safe' levels for these elements, each country has its own standard, but the majority of the present specifications for the lead used to prepare battery oxide apply to flooded batteries that employ antimonial grids. In these batteries, the antimony in the positive and negative grids dominates gassing characteristics so that the influence of residual elements is of little importance. This is, however, not the case for valve-regulated lead-acid (VRLA) batteries, which use antimony-free grids and less sulfuric acid solution. Thus, it is necessary to specify 'acceptable' levels of residual elements for the production of VRLA batteries. In this study, 17 elements are examined, namely: antimony, arsenic, bismuth, cadmium, chromium, cobalt, copper, germanium, iron, manganese, nickel, selenium, silver, tellurium, thallium, tin, and zinc. The following strategy has been formulated to determine the acceptable levels: (i) selection of a control oxide; (ii) determination of critical float, hydrogen and oxygen currents; (iii) establishment of a screening plan for the elements; (iv) development of a statistical method for analysis of the experimental results. The critical values of the float, hydrogen and oxygen currents are calculated from a field survey of battery failure data. The values serve as a base-line for comparison with the corresponding measured currents from cells using positive and negative plates produced either from the control oxide or from oxide doped with different levels of the 17 elements in combination. The latter levels are determined by means of a screening plan which is based on the Plackett-Burman experimental design. Following this systematic and thorough exercise, two specifications are proposed for the purity of the lead to be used in oxide production for VRLA technology.

  18. Composition, production rate and characterization of Greek dental solid waste.

    Science.gov (United States)

    Mandalidis, Alexandros; Topalidis, Antonios; Voudrias, Evangelos A; Iosifidis, Nikolaos

    2018-05-01

    The overall objective of this work is to determine the composition, characterization and production rate of Greek dental solid waste (DSW). This information is important to design and cost management systems for DSW, for safety and health considerations and for assessing environmental impact. A total of 141 kg of DSW produced by a total of 2542 patients in 20 dental practices from Xanthi, Greece was collected, manually separated and weighed over a period of four working weeks. The waste was separated in 19 sub fractions, which were classified in 2 major categories, according to Greek regulations: Domestic-type waste comprising 8% and hazardous waste comprising 92% by weight of total DSW. The latter was further classified in infectious waste, toxic waste and mixed type waste (infectious and toxic together), accounting for 88.5%, 3.5% and 0.03% of total DSW by weight, respectively. The overall unit production rates (mean ± standard error of the mean) were 381 ± 15 g/practice/d and 53.3 ± 1.4 g/patient/d for total DSW, 337 ± 14 g/practice/d and 46.6 ± 1.2 g/patient/d for total infectious DSW, 13.4 ± 0.7 g/practice/d and 2.1 ± 0.1 g/patient/d for total toxic DSW and 30.4 ± 2.5 g/practice/d and 4.6 ± 0.4 g/patient/d for domestic-type waste. Daily DSW production was correlated with daily number of patients and regression correlations were produced. DSW was subject to laboratory characterization in terms of bulk density, calorific value, moisture, ash and volatile solids content. Measured calorific values were compared to predictions from empirical models. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. 50 CFR Table 3 to Part 679 - Product Recovery Rates for Groundfish Species and Conversion Rates for Pacific Halibut

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Product Recovery Rates for Groundfish Species and Conversion Rates for Pacific Halibut 3 Table 3 to Part 679 Wildlife and Fisheries FISHERY... Rates for Groundfish Species and Conversion Rates for Pacific Halibut ER28JA02.074 ER10JY02.000 ER28JA02...

  20. Diffusion and Monod kinetics model to determine in vivo human corneal oxygen-consumption rate during soft contact lens wear

    Directory of Open Access Journals (Sweden)

    Luis F. Del Castillo

    2015-01-01

    Conclusion: Present results are relevant for the calculation on the partial pressure of oxygen, available at different depths into the corneal tissue behind contact lenses of different oxygen transmissibility.

  1. 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

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

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  3. The hydrolytic stage in high solids temperature phased anaerobic digestion improves the downstream methane production rate.

    Science.gov (United States)

    Buffière, P; Dooms, M; Hattou, S; Benbelkacem, H

    2018-07-01

    The role of the hydrolytic stage in high solids temperature phased anaerobic digestion was investigated with a mixture of cattle slurry and maize silage with variable ratios (100, 70 and 30% volatile solids coming from cattle slurry). It was incubated for 48 h at 37, 55, 65 and 72 °C. Soluble chemical oxygen demand and biochemical methane potential were measured at 0, 24 and 48 h. Higher temperatures improved the amount of solubilized COD, which confirmed previously reported results. Nevertheless, solubilization mostly took place during the first 24 h. The rate of methane production in post-hydrolysis BMPs increased after 48 h hydrolysis time, but not after 24 h. The first order kinetic constant rose by 40% on average. No correlation was observed between soluble COD and downstream methane production rate, indicating a possible modification of the physical structure of the particulate solids during the hydrolytic stage. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Effects of zilpaterol hydrochloride on methane production, total body oxygen consumption, and blood metabolites in finishing beef steers

    Science.gov (United States)

    An indirect calorimetry experiment was conducted to determine the effects of feeding zilpaterol hydrochloride (ZH) for 20 d on total body oxygen consumption, respiratory quotient, methane production, and blood metabolites in finishing beef steers. Sixteen Angus steers (initial BW = 555 ± 12.7 kg) w...

  5. Acetylene and oxygen as inhibitors of nitrous oxide production in Nitrosomonas europaea and Nitrosospira briensis: a cautionary tale

    NARCIS (Netherlands)

    Wrage, N.; Velthof, G.L.; Oenema, O.; Laanbroek, H.J.

    2004-01-01

    Autotrophic ammonia-oxidizing bacteria produce nitrous oxide (N2O) as a by-product of nitrification or as an intermediate of nitrifier denitrification. In soil incubations, acetylene (C2H2) and large partial pressures of oxygen (O2) are used to distinguish between these sources. C2H2 inhibits

  6. URCA neutrino-loss rates under conditions found in the carbon-oxygen cores of intermediate-mass stars

    International Nuclear Information System (INIS)

    Iben, I. Jr.

    1978-01-01

    In the hope of uncovering additional Urca-active nuclei that might appear during carbon burning in the electron-degenerate carbon-oxygen core of an asymptotic-branch star and avert a thermonuclear runaway, a nuclear-reaction matrix connecting 244 nuclear species has been constructed. Analytic expressions for rates of all relevant β-transitions are also presented and used. It is shown that in matter which is composed initially of elements in a solar-system distribution and which has undergone first complete hydrogen burning and then complete helium burning, neutrino-loss rates due to 11 Urca pairs either rival or exceed neutrino losses predicted by the charge- and neutral-current theories of weak interactions. Most remarkably, no new Urca pairs of any consequence appear as a result of several thousand reactions that are allowed to occur during carbon burning. The dominant Urca-loss rates are still due to the pairs 21 F- 21 Ne, 23 Ne- 23 Na, 25 Na- 25 Mg, and 25 Ne- 25 Na, as in matter containing a solar-system distribution of elements that has undergone prior processing during hydrogen- and helium-burning phases. The abundances of these Urca-active pairs are enhanced by one to three orders of magnitude as a consequence of carbon-burning reactions

  7. Relationship between oxygen uptake slow component and surface EMG during heavy exercise in humans: influence of pedal rate.

    Science.gov (United States)

    Vercruyssen, Fabrice; Missenard, Olivier; Brisswalter, Jeanick

    2009-08-01

    The aim of this study was to test the hypothesis that extreme pedal rates contributed to the slow component of oxygen uptake (VO(2) SC) in association with changes in surface electromyographic (sEMG) during heavy-cycle exercise. Eight male trained cyclists performed two square-wave transitions at 50 and 110 rpm at a work rate that would elicit a VO(2) corresponding to 50% of the difference between peak VO(2) and the ventilatory threshold. Pulmonary gas exchange was measured breath-by-breath and sEMG was obtained from the vastus lateralis and medialis muscles. Integrated EMG flow (QiEMG) and mean power frequency (MPF) were computed. The relative amplitude of the VO(2) SC was significantly higher during the 110-rpm bout (556+/-186 ml min(-1), Pexercise only during the 110-rpm bout and were associated with the greater amplitude of the VO(2) SC observed for this condition (Pmotor units recruitment pattern, muscle energy turnover and muscle temperature have been suggested to explain the different VO(2) SC to heavy pedal rate bouts.

  8. 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

  9. Shelf erosion and submarine river canyons: implications for deep-sea oxygenation and ocean productivity during glaciation

    Directory of Open Access Journals (Sweden)

    I. Tsandev

    2010-06-01

    Full Text Available The areal exposure of continental shelves during glacial sea level lowering enhanced the transfer of erodible reactive organic matter to the open ocean. Sea level fall also activated submarine canyons thereby allowing large rivers to deposit their particulate load, via gravity flows, directly in the deep-sea. Here, we analyze the effects of shelf erosion and particulate matter re-routing to the open ocean during interglacial to glacial transitions, using a coupled model of the marine phosphorus, organic carbon and oxygen cycles. The results indicate that shelf erosion and submarine canyon formation may significantly lower deep-sea oxygen levels, by up to 25%, during sea level low stands, mainly due to the supply of new material from the shelves, and to a lesser extent due to particulate organic matter bypassing the coastal zone. Our simulations imply that deep-sea oxygen levels can drop significantly if eroded shelf material is deposited to the seafloor. Thus the glacial ocean's oxygen content could have been significantly lower than during interglacial stages. Primary production, organic carbon burial and dissolved phosphorus inventories are all affected by the erosion and rerouting mechanisms. However, re-routing of the continental and eroded shelf material to the deep-sea has the effect of decoupling deep-sea oxygen demand from primary productivity in the open ocean. P burial is also not affected showing a disconnection between the biogeochemical cycles in the water column and the P burial record.

  10. Production of perhydroxy radical (HO2) and oxygen in the radiolysis of aqueous solution and the LET effects

    International Nuclear Information System (INIS)

    Imamura, Masashi

    1987-01-01

    This article aims to review the results concerning the production of perhydroxy radical (HO 2 ) and oxygen from irradiated aqueous solutions and the LET effects on these products, beginning with a brief introduction to the elementary primary processes in radiolysis of aqueous solution. Oxygen, if produced in the radiolysis of aqueous solution, may be considered responsible for the decreased oxygen enhancement ratio (OER) in biological systems exposed to high LET radiation. A Harwell's group has determined oxygen generated from aqueous ferrous solutions irradiated with heavy ions and concluded that the oxygen is a precursor of perhydroxy radicals. The LET-dependent yields for perhydroxy radical have been determined by LaVerne and Schuler; the analysis of their results sheds light into the reactions taking place in high-LET track cores. In conjunction with these results, the possible contributions to the LET effects are pointed out and discussed of the energetic secondary electrons ejected from the track core by knock-on collision with heavy ions and of the variation in the track core size with energy of the heavy particles. (author)

  11. Analysis of two production inventory systems with buffer, retrials and different production rates

    Science.gov (United States)

    Jose, K. P.; Nair, Salini S.

    2017-09-01

    This paper considers the comparison of two ( {s,S} ) production inventory systems with retrials of unsatisfied customers. The time for producing and adding each item to the inventory is exponentially distributed with rate β. However, a production rate α β higher than β is used at the beginning of the production. The higher production rate will reduce customers' loss when inventory level approaches zero. The demand from customers is according to a Poisson process. Service times are exponentially distributed. Upon arrival, the customers enter into a buffer of finite capacity. An arriving customer, who finds the buffer full, moves to an orbit. They can retry from there and inter-retrial times are exponentially distributed. The two models differ in the capacity of the buffer. The aim is to find the minimum value of total cost by varying different parameters and compare the efficiency of the models. The optimum value of α corresponding to minimum total cost is an important evaluation. Matrix analytic method is used to find an algorithmic solution to the problem. We also provide several numerical or graphical illustrations.

  12. Selective conversion of synthesis gas into C2-oxygenated products using mixed-metal homogeneous catalysts

    International Nuclear Information System (INIS)

    Whyman, R.

    1986-01-01

    A feature which is a key to any wider utilization of chemistry based on synthesis gas is an understanding of, and more particularly, an ability to control, those factors which determine the selectivity of the C 1 to C 2 transformation during the hydrogenation of carbon monoxide. With the exception of the rhodium-catalyzed conversion of carbon monoxide and hydrogen into ethylene glycol and methanol, in which molar ethylene glycol/methanol selectivities of ca 2/1 may be achieved, other catalyst systems containing metals such as cobalt or ruthenium exhibit only poor selectivities to ethylene glycol. The initial studies in this area were based on the reasoning that, since the reduction of carbon monoxide to C 2 products is a complex, multi-step process, the use of appropriate combinations of metals could generate synergistic effects which might prove more effective (in terms of both catalytic activity and selectivity) than simply the sum of the individual metal components. In particular, the concept of the combination of a good hydrogenation catalyst with a good carbonylation, or ''CO insertion'', catalyst seemed particularly germane. As a result of this approach the authors discovered an unprecedented example of the effect of catalyst promoters, particularly in the enhancement of C 2 /C 1 selectivity, and one which has led to the development of composite mixed-metal homogeneous catalyst systems for the conversion of CO/H 2 into C 2 -oxygenate esters

  13. Reactive oxygen species production and Brugia pahangi survivorship in Aedes polynesiensis with artificial Wolbachia infection types.

    Directory of Open Access Journals (Sweden)

    Elizabeth S Andrews

    Full Text Available Heterologous transinfection with the endosymbiotic bacterium Wolbachia has been shown previously to induce pathogen interference phenotypes in mosquito hosts. Here we examine an artificially infected strain of Aedes polynesiensis, the primary vector of Wuchereria bancrofti, which is the causative agent of Lymphatic filariasis (LF throughout much of the South Pacific. Embryonic microinjection was used to transfer the wAlbB infection from Aedes albopictus into an aposymbiotic strain of Ae. polynesiensis. The resulting strain (designated "MTB" experiences a stable artificial infection with high maternal inheritance. Reciprocal crosses of MTB with naturally infected wild-type Ae. polynesiensis demonstrate strong bidirectional incompatibility. Levels of reactive oxygen species (ROS in the MTB strain differ significantly relative to that of the wild-type, indicating an impaired ability to regulate oxidative stress. Following a challenge with Brugia pahangi, the number of filarial worms achieving the infective stage is significantly reduced in MTB as compared to the naturally infected and aposymbiotic strains. Survivorship of MTB differed significantly from that of the wild-type, with an interactive effect between survivorship and blood feeding. The results demonstrate a direct correlation between decreased ROS levels and decreased survival of adult female Aedes polynesiensis. The results are discussed in relation to the interaction of Wolbachia with ROS production and antioxidant expression, iron homeostasis and the insect immune system. We discuss the potential applied use of the MTB strain for impacting Ae. polynesiensis populations and strategies for reducing LF incidence in the South Pacific.

  14. Photoreactivity of Metal-Organic Frameworks in Aqueous Solutions: Metal Dependence of Reactive Oxygen Species Production.

    Science.gov (United States)

    Liu, Kai; Gao, Yanxin; Liu, Jing; Wen, Yifan; Zhao, Yingcan; Zhang, Kunyang; Yu, Gang

    2016-04-05

    Promising applications of metal-organic frameworks (MOFs) in various fields have raised concern over their environmental fate and safety upon inevitable discharge into aqueous environments. Currently, no information regarding the transformation processes of MOFs is available. Due to the presence of repetitive π-bond structure and semiconductive property, photochemical transformations are an important fate process that affects the performance of MOFs in practical applications. In the current study, the generation of reactive oxygen species (ROS) in isoreticular MIL-53s was studied. Scavengers were employed to probe the production of (1)O2, O2(•-), and •OH, respectively. In general, MIL-53(Cr) and MIL-53(Fe) are dominated by type I and II photosensitization reactions, respectively, and MIL-53(Al) appears to be less photoreactive. The generation of ROS in MIL-53(Fe) may be underestimated due to dismutation. Further investigation of MIL-53(Fe) encapsulated diclofenac transformation revealed that diclofenac can be easily transformed by MIL-53(Fe) generated ROS. However, the cytotoxicity results implied that the ROS generated from MIL-53s have little effect on the viability of the human hepatocyte (HepG2) cell line. These results suggest that the photogeneration of ROS by MOFs may be metal-node dependent, and the application of MIL-53s as drug carriers needs to be carefully considered due to their high photoreactivity.

  15. Scoparone attenuates RANKL-induced osteoclastic differentiation through controlling reactive oxygen species production and scavenging

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang-Hyun; Jang, Hae-Dong, E-mail: haedong@hnu.kr

    2015-02-15

    Scoparone, one of the bioactive components of Artemisia capillaris Thunb, has various biological properties including immunosuppressive, hepatoprotective, anti-allergic, anti-inflammatory, and antioxidant effects. This study aims at evaluating the anti-osteoporotic effect of scoparone and its underlying mechanism in vitro. Scoparone demonstrated potent cellular antioxidant capacity. It was also found that scoparone inhibited the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation and suppressed cathepsin K and tartrate-resistant acid phosphatase (TRAP) expression via c-jun N-terminal kinase (JNK)/extracellular signal-regulated kinase (ERK)/p38-mediated c-Fos–nuclear factor of activated T cells, cytoplasmic 1 (NFATc1) signaling pathway. During osteoclast differentiation, the production of general reactive oxygen species (ROS) and superoxide anions was dose-dependently attenuated by scoparone. In addition, scoparone diminished NADPH (nicotinamide adenine dinucleotide phosphate) oxidase 1 (Nox1) expression and activation via the tumor necrosis factor receptor-associated factor 6 (TRAF6)–cSrc–phosphatidylinositol 3-kinase (PI3k) signaling pathway and prevented the disruption of mitochondrial electron transport chain system. Furthermore, scoparone augmented the expression of superoxide dismutase 1 (SOD1) and catalase (CAT). The overall results indicate that the inhibitory effect of scoparone on RANKL-induced osteoclast differentiation is attributed to the suppressive effect on ROS and superoxide anion production by inhibiting Nox1 expression and activation and protecting the mitochondrial electron transport chain system and the scavenging effect of ROS resulting from elevated SOD1 and CAT expression. - Highlights: • Scoparone dose-dependently inhibited RANKL-induced osteoclast differentiation. • Scoparone diminished general ROS and superoxide anions in a dose-dependent manner. • Scoparone inhibited Nox1 expression and

  16. Sibutramine provokes apoptosis of aortic endothelial cells through altered production of reactive oxygen and nitrogen species

    Energy Technology Data Exchange (ETDEWEB)

    Morikawa, Yoshifumi [Forensic Science Laboratory, Gifu Prefectural Police Headquarters, Gifu 500-8501 (Japan); Shibata, Akinobu; Okumura, Naoko; Ikari, Akira [Laboratory of Biochemistry, Gifu Pharmaceutical University, Gifu 501-1196 (Japan); Sasajima, Yasuhide; Suenami, Koichi; Sato, Kiyohito; Takekoshi, Yuji [Forensic Science Laboratory, Gifu Prefectural Police Headquarters, Gifu 500-8501 (Japan); El-Kabbani, Ossama [Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Matsunaga, Toshiyuki, E-mail: matsunagat@gifu-pu.ac.jp [Laboratory of Biochemistry, Gifu Pharmaceutical University, Gifu 501-1196 (Japan)

    2017-01-01

    Overdose administration of sibutramine, a serotonin-noradrenalin reuptake inhibitor, is considered to elicit severe side effects including hypertension, whose pathogenic mechanism remains unclear. Here, we found that 48-h incubation with > 10 μM sibutramine provokes apoptosis of human aortic endothelial (HAE) cells. Treatment with the lethal concentration of sibutramine facilitated production of reactive oxygen species (ROS), altered expression of endoplasmic reticulum stress response genes (heat shock protein 70 and C/EBP homologous protein), and inactivated 26S proteasome-based proteolysis. The treatment also decreased cellular level of nitric oxide (NO) through lowering of expression and activity of endothelial NO synthase. These results suggest that ROS production and depletion of NO are crucial events in the apoptotic mechanism and may be linked to the pathogenesis of vasoconstriction elicited by the drug. Compared to sibutramine, its metabolites (N-desmethylsibutramine and N-didesmethylsibutramine) were much less cytotoxic to HAE cells, which hardly metabolized sibutramine. In contrast, both the drug and metabolites showed low cytotoxicity to hepatic HepG2 cells with high metabolic potency and expression of cytochrome P450 (CYP) 3A4. The cytotoxicity of sibutramine to HepG2 and Chang Liver cells was remarkably augmented by inhibition and knockdown of CYP3A4. This study also suggests an inverse relationship between sibutramine cytotoxicity and CYP3A4-mediated metabolism into the N-desmethyl metabolites. - Highlights: • Treatment with sibutramine, an anorexiant, induces endothelial cell apoptosis. • The apoptotic mechanism includes induction of ROS and NO depletion. • There is an inverse relationship between sibutramine cytotoxicity and its metabolism.

  17. Exposure to ultrafine particles, intracellular production of reactive oxygen species in leukocytes and altered levels of endothelial progenitor cells

    International Nuclear Information System (INIS)

    Jantzen, Kim; Møller, Peter; Karottki, Dorina Gabriela; Olsen, Yulia; Bekö, Gabriel; Clausen, Geo; Hersoug, Lars-Georg; Loft, Steffen

    2016-01-01

    Exposure to particles in the fine and ultrafine size range has been linked to induction of low-grade systemic inflammation, oxidative stress and development of cardiovascular diseases. Declining levels of endothelial progenitor cells within systemic circulation have likewise been linked to progression of cardiovascular diseases. The objective was to determine if exposure to fine and ultrafine particles from indoor and outdoor sources, assessed by personal and residential indoor monitoring, is associated with altered levels of endothelial progenitor cells, and whether such effects are related to leukocyte-mediated oxidative stress. The study utilized a cross sectional design performed in 58 study participants from a larger cohort. Levels of circulating endothelial progenitor cells, defined as either late (CD34 + KDR + cells) or early (CD34 + CD133 + KDR + cells) subsets were measured using polychromatic flow cytometry. We additionally measured production of reactive oxygen species in leukocyte subsets (lymphocytes, monocytes and granulocytes) by flow cytometry using intracellular 2′,7′-dichlorofluoroscein. The measurements encompassed both basal levels of reactive oxygen species production and capacity for reactive oxygen species production for each leukocyte subset. We found that the late endothelial progenitor subset was negatively associated with levels of ultrafine particles measured within the participant residences and with reactive oxygen species production capacity in lymphocytes. Additionally, the early endothelial progenitor cell levels were positively associated with a personalised measure of ultrafine particle exposure and negatively associated with both basal and capacity for reactive oxygen species production in lymphocytes and granulocytes, respectively. Our results indicate that exposure to fine and ultrafine particles derived from indoor sources may have adverse effects on human vascular health.

  18. HIV antiretroviral drug combination induces endothelial mitochondrial dysfunction and reactive oxygen species production, but not apoptosis

    International Nuclear Information System (INIS)

    Jiang Bo; Hebert, Valeria Y.; Li, Yuchi; Mathis, J. Michael; Alexander, J. Steven; Dugas, Tammy R.

    2007-01-01

    Numerous reports now indicate that HIV patients administered long-term antiretroviral therapy (ART) are at a greater risk for developing cardiovascular diseases. Endothelial dysfunction is an initiating event in atherogenesis and may contribute to HIV-associated atherosclerosis. We previously reported that ART induces direct endothelial dysfunction in rodents. In vitro treatment of human umbilical vein endothelial cells (HUVEC) with ART indicated endothelial mitochondrial dysfunction and a significant increase in the production of reactive oxygen species (ROS). In this study, we determined whether ART-induced endothelial dysfunction is mediated via mitochondria-derived ROS and whether this mitochondrial injury culminates in endothelial cell apoptosis. Two major components of ART combination therapy, a nucleoside reverse transcriptase inhibitor and a protease inhibitor, were tested, using AZT and indinavir as representatives for each. Microscopy utilizing fluorescent indicators of ROS and mitochondria demonstrated the mitochondrial localization of ART-induced ROS. MnTBAP, a cell-permeable metalloporphyrin antioxidant, abolished ART-induced ROS production. As a final step in confirming the mitochondrial origin of the ART-induced ROS, HUVEC were transduced with a cytosolic- compared to a mitochondria-targeted catalase. Transduction with the mitochondria-targeted catalase was more effective than cytoplasmic catalase in inhibiting the ROS and 8-isoprostane (8-iso-PGF 2α ) produced after treatment with either AZT or indinavir. However, both mitochondrial and cytoplasmic catalase attenuated ROS and 8-iso-PGF 2α production induced by the combination treatment, suggesting that in this case, the formation of cytoplasmic ROS may also occur, and thus, that the mechanism of toxicity in the combination treatment group may be different compared to treatment with AZT or indinavir alone. Finally, to determine whether ART-induced mitochondrial dysfunction and ROS production

  19. Hekla Volcano, Iceland, in the 20th Century: Lava Volumes, Production Rates, and Effusion Rates

    Science.gov (United States)

    Pedersen, G. B. M.; Belart, J. M. C.; Magnússon, E.; Vilmundardóttir, O. K.; Kizel, F.; Sigurmundsson, F. S.; Gísladóttir, G.; Benediktsson, J. A.

    2018-02-01

    Lava flow thicknesses, volumes, and effusion rates provide essential information for understanding the behavior of eruptions and their associated deformation signals. Preeruption and posteruption elevation models were generated from historical stereo photographs to produce the lava flow thickness maps for the last five eruptions at Hekla volcano, Iceland. These results provide precise estimation of lava bulk volumes: V1947-1948 = 0.742 ± 0.138 km3, V1970 = 0.205 ± 0.012 km3, V1980-1981 = 0.169 ± 0.016 km3, V1991 = 0.241 ± 0.019 km3, and V2000 = 0.095 ± 0.005 km3 and reveal variable production rate through the 20th century. These new volumes improve the linear correlation between erupted volume and coeruption tilt change, indicating that tilt may be used to determine eruption volume. During eruptions the active vents migrate 325-480 m downhill, suggesting rough excess pressures of 8-12 MPa and that the gradient of this excess pressure increases from 0.4 to 11 Pa s-1 during the 20th century. We suggest that this is related to increased resistance along the eruptive conduit.

  20. Modeling gallic acid production rate by empirical and statistical analysis

    Directory of Open Access Journals (Sweden)

    Bratati Kar

    2000-01-01

    Full Text Available For predicting the rate of enzymatic reaction empirical correlation based on the experimental results obtained under various operating conditions have been developed. Models represent both the activation as well as deactivation conditions of enzymatic hydrolysis and the results have been analyzed by analysis of variance (ANOVA. The tannase activity was found maximum at incubation time 5 min, reaction temperature 40ºC, pH 4.0, initial enzyme concentration 0.12 v/v, initial substrate concentration 0.42 mg/ml, ionic strength 0.2 M and under these optimal conditions, the maximum rate of gallic acid production was 33.49 mumoles/ml/min.Para predizer a taxa das reações enzimaticas uma correlação empírica baseada nos resultados experimentais foi desenvolvida. Os modelos representam a ativação e a desativativação da hydrolise enzimatica. Os resultados foram avaliados pela análise de variança (ANOVA. A atividade máxima da tannase foi obtida após 5 minutos de incubação, temperatura 40ºC, pH 4,0, concentração inicial da enzima de 0,12 v/v, concentração inicial do substrato 0,42 mg/ml, força iônica 0,2 M. Sob essas condições a taxa máxima de produção ácido galico foi de 33,49 µmoles/ml/min.

  1. Metabolic clearance and blood production rates of estradiol in hyperthyroidism.

    Science.gov (United States)

    Ridgway, E C; Longcope, C; Maloof, F

    1975-09-01

    The metabolic clearance rate of 17beta-estradiol (MCR2), the plasma levels of 17beta-estradiol (E2)1, sex-steroid binding globulin (SSBG), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured in 10 hyperthyroid subjects (7 men and 3 women). The blood production rate of 17beta-estradiol (PB2) was calculated for all subjects. Nine of the 10 hyperthyroid subjects had a decreased MCR2 which returned towards normal in 5 of the 6 subjects restudied following therapy. In all 10 subjects the levels of SSBG were increased when they were hyperthyroid and returned toward normal with therapy. It is concluded that the decrease in MCR2 is largely due to the increased binding of 17beta-estradiol to SSBG. In 7 of the 10 hyperthyroid the plasma E2 concentrations were normal whereas 3 had slightly elevated levels. In 8 of the 10 hyperthyroid the PB2 was within the normal range. Only 2 hyperthyroid subjects had slightly elevated PB2. In the 6 subjects who were restudied after therapy, there was no consistent change in PB2 which remained in the normal range in all cases. It is concluded that the MCR2 is decreased in most subjects with hyperthyroidism in association with an increase of SSBG. Despite this change in MCR2 there is no significant change in PB2. The increase in SSBG levels in hyperthyroidism appears to be a direct effect of the elevation of thyroid hormone activity and is not mediated through estrogen.

  2. Low energy consumption method for separating gaseous mixtures and in particular for medium purity oxygen production

    Science.gov (United States)

    Jujasz, Albert J.; Burkhart, James A.; Greenberg, Ralph

    1988-01-01

    A method for the separation of gaseous mixtures such as air and for producing medium purity oxygen, comprising compressing the gaseous mixture in a first compressor to about 3.9-4.1 atmospheres pressure, passing said compressed gaseous mixture in heat exchange relationship with sub-ambient temperature gaseous nitrogen, dividing the cooled, pressurized gaseous mixture into first and second streams, introducing the first stream into the high pressure chamber of a double rectification column, separating the gaseous mixture in the rectification column into a liquid oxygen-enriched stream and a gaseous nitrogen stream and supplying the gaseous nitrogen stream for cooling the compressed gaseous mixture, removing the liquid oxygen-enriched stream from the low pressure chamber of the rectification column and pumping the liquid, oxygen-enriched steam to a predetermined pressure, cooling the second stream, condensing the cooled second stream and evaporating the oxygen-enriched stream in an evaporator-condenser, delivering the condensed second stream to the high pressure chamber of the rectification column, and heating the oxygen-enriched stream and blending the oxygen-enriched stream with a compressed blend-air stream to the desired oxygen concentration.

  3. Photosensitized production of singlet oxygen: spatially-resolved optical studies in single cells

    DEFF Research Database (Denmark)

    Breitenbach, Thomas; Kuimova, Marina; Gbur, Peter

    2009-01-01

    be monitored using viability assays. Time- and spatially-resolved optical measurements of both singlet oxygen and its precursor, the excited state sensitizer, reflect the complex and dynamic morphology of the cell. These experiments help elucidate photoinduced, oxygen-dependent events that compromise cell...

  4. Metabolic clearance and production rates of human growth hormone

    Science.gov (United States)

    Taylor, Andrew L.; Finster, Joseph L.; Mintz, Daniel H.

    1969-01-01

    The metabolic clearance rate (MCR) of human growth hormone (HGH) was determined by the constant infusion to equilibrium technique utilizing HGH-125I. 22 control subjects had a MCR of 229 ±52 ml/min (mean ±SD). No difference was evident between sexes, or between various age groups. Patients with acromegaly demonstrated normal MCR's. Moreover, acute elevations of plasma growth hormone concentrations in normal subjects did not alter the MCR of HGH. The MCR was relatively constant from day to day and within the day when subjects were evaluated in the supine position. In contrast, the assumption of the upright position was associated with a mean 24% decrease in the MCR. These results were contrasted with the MCR of HGH observed in a small number of patients with altered thyroid function or diabetes mellitus. In six patients with hypothyroidism the MCR (131 ±36 ml/min) was significantly decreased (P < 0.001); whereas the MCR in eight patients with hyperthyroidism (240 ±57 ml/min) did not differ from control subjects. The MCR in eight patients with insulin-independent diabetes mellitus (IID) (185 ±41 ml/min) and in eight patients with insulin-dependent diabetes mellitus (IDD) (136 ±31 ml/min) were significantly different from control subjects (P = < 0.05 and P = < 0.001, respectively). These data were interpreted to indicate that the plasma HGH-removing mechanism(s) is not saturated at physiologic plasma HGH levels, that plasma HGH levels alone may not permit distinction between variations in pituitary release of the hormone and its rate of clearance from the plasma, and that the estimation of the MCR of HGH may help clarify the mechanism of abnormal plasma HGH responses to various stimuli. Production rates of HGH (PR) in control subjects (347 ±173 mμg/min) were contrasted with hyperthyroid patients (529 ±242 mμg/min, P < 0.05), hypothyroid patients (160 ±69 mμg/min, P < 0.02), IID (245 ±100 mμg/min, NS), and IDD (363 ±153 mμg/min, NS). Considerable

  5. Mobile phone radiation induces reactive oxygen species production and DNA damage in human spermatozoa in vitro.

    Directory of Open Access Journals (Sweden)

    Geoffry N De Iuliis

    Full Text Available BACKGROUND: In recent times there has been some controversy over the impact of electromagnetic radiation on human health. The significance of mobile phone radiation on male reproduction is a key element of this debate since several studies have suggested a relationship between mobile phone use and semen quality. The potential mechanisms involved have not been established, however, human spermatozoa are known to be particularly vulnerable to oxidative stress by virtue of the abundant availability of substrates for free radical attack and the lack of cytoplasmic space to accommodate antioxidant enzymes. Moreover, the induction of oxidative stress in these cells not only perturbs their capacity for fertilization but also contributes to sperm DNA damage. The latter has, in turn, been linked with poor fertility, an increased incidence of miscarriage and morbidity in the offspring, including childhood cancer. In light of these associations, we have analyzed the influence of RF-EMR on the cell biology of human spermatozoa in vitro. PRINCIPAL FINDINGS: Purified human spermatozoa were exposed to radio-frequency electromagnetic radiation (RF-EMR tuned to 1.8 GHz and covering a range of specific absorption rates (SAR from 0.4 W/kg to 27.5 W/kg. In step with increasing SAR, motility and vitality were significantly reduced after RF-EMR exposure, while the mitochondrial generation of reactive oxygen species and DNA fragmentation were significantly elevated (P<0.001. Furthermore, we also observed highly significant relationships between SAR, the oxidative DNA damage bio-marker, 8-OH-dG, and DNA fragmentation after RF-EMR exposure. CONCLUSIONS: RF-EMR in both the power density and frequency range of mobile phones enhances mitochondrial reactive oxygen species generation by human spermatozoa, decreasing the motility and vitality of these cells while stimulating DNA base adduct formation and, ultimately DNA fragmentation. These findings have clear implications

  6. Maximum Plant Uptakes for Water, Nutrients, and Oxygen Are Not Always Met by Irrigation Rate and Distribution in Water-based Cultivation Systems

    NARCIS (Netherlands)

    Blok, Chris; Jackson, Brian E.; Guo, Xianfeng; Visser, De Pieter H.B.; Marcelis, Leo F.M.

    2017-01-01

    Growing on rooting media other than soils in situ -i.e., substrate-based growing- allows for higher yields than soil-based growing as transport rates of water, nutrients, and oxygen in substrate surpass those in soil. Possibly water-based growing allows for even higher yields as transport rates of

  7. Cortisol production rates measured by liquid chromatography/mass spectrometry

    International Nuclear Information System (INIS)

    Esteban, N.V.; Yergey, A.L.

    1990-01-01

    Cortisol production rates (FPRs) in physiologic and pathologic states in humans have been investigated over the past 30 years. However, there has been conflicting evidence concerning the validity of the currently accepted value of FPRs in humans (12 to 15 mg/m2/d) as determined by radiotracer methodology. The present study reviews previous methods proposed for the measurement of FPRs in humans and discusses the applications of the first method for the direct determination of 24-hour plasma FPRs during continuous administration of a stable isotope, using a thermospray high-pressure liquid chromatography-mass spectrometry technique. The technique is fast, sensitive, and, unlike gas chromatography-mass spectrometry methods, does not require derivatization, allowing on-line detection and quantification of plasma cortisol after a simple extraction procedure. The results of determination of plasma FPRs by stable tracer/mass spectrometry are directly in units of mass/time and, unlike radiotracer methods, are independent of any determination of volume of distribution or cortisol concentration. Our methodology offers distinct advantages over radiotracer techniques in simplicity and reliability since only single measurements of isotope ratios are required. The technique was validated in adrenalectomized patients. Circadian variations in daily FRPs were observed in normal volunteers, and, to date, results suggest a lower FRP in normal children and adults than previously believed. 88 references

  8. MATHEMATICAL MODELING OF HEATING RATE PRODUCT AT HIGH HEAT TREATMENT

    Directory of Open Access Journals (Sweden)

    M. M. Akhmedova

    2014-01-01

    Full Text Available Methods of computing and mathematical modeling are all widely used in the study of various heat exchange processes that provide the ability to study the dynamics of the processes, as well as to conduct a reasonable search for the optimal technological parameters of heat treatment.This work is devoted to the identification of correlations among the factors that have the greatest effect on the rate of heating of the product at hightemperature heat sterilization in a stream of hot air, which are chosen as the temperature difference (between the most and least warming up points and speed cans during heat sterilization.As a result of the experimental data warming of the central and peripheral layers compote of apples in a 3 liter pot at high-temperature heat treatment in a stream of hot air obtained by the regression equation in the form of a seconddegree polynomial, taking into account the effects of pair interaction of these parameters. 

  9. The compositional study of nitrogen and oxygen compounds in products of heavy oil primary and secondary upgrading processes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Chmielowiec, J.

    1986-02-01

    The primary objective was to characterize nitrogen and oxygen compound types in the upgraded products derived from Athabasca bitumen. Nitrogen compounds, depending on their nature and concentrations, in charge stocks to catalytic processess (hydro-processes and reforming) can severely limit or poison the catalyst activity. Oxygen compounds are corrosive (especially naphthenic acids) and can promote gum formation as part of the deterioration of the hydrocarbons in the petroleum product. A secondary objective was to evaluate the advantages and limitations of in-house mass spectrometry and infrared spectroscopy methods for analyzing specific classes of polar compounds in naphthas, middle distillates, and gas oils. An analytical procedure that was based on the discrimination of polar compound classes using liquid chromatography followed by mass spectrometric analysis was tested. The chemical intelligence on the fractions obtained from Athabasca bitumen and its upgrading products has been advanced by determining structural characteristics of the nitrogen and oxygen components. This report describes the determination of the distributions of nitrogen and oxygen compounds in samples from various process streams. This procedure is capable of providing information useful for evaluating hydrodenitrogenation and hydrodeoxygenation reactions.

  10. Do interindividual differences in cardiac output during submaximal exercise explain differences in exercising muscle oxygenation and ratings of perceived exertion?

    Science.gov (United States)

    Bentley, Robert F; Jones, Joshua H; Hirai, Daniel M; Zelt, Joel T; Giles, Matthew D; Raleigh, James P; Quadrilatero, Joe; Gurd, Brendon J; Neder, J Alberto; Tschakovsky, Michael E

    2018-01-01

    Considerable interindividual differences in the Q˙-V˙O2 relationship during exercise have been documented but implications for submaximal exercise tolerance have not been considered. We tested the hypothesis that these interindividual differences were associated with differences in exercising muscle deoxygenation and ratings of perceived exertion (RPE) across a range of submaximal exercise intensities. A total of 31 (21 ± 3 years) healthy recreationally active males performed an incremental exercise test to exhaustion 24 h following a resting muscle biopsy. Cardiac output (Q˙ L/min; inert gas rebreathe), oxygen uptake (V˙O2 L/min; breath-by-breath pulmonary gas exchange), quadriceps saturation (near infrared spectroscopy) and exercise tolerance (6-20; Borg Scale RPE) were measured. The Q˙-V˙O2 relationship from 40 to 160 W was used to partition individuals post hoc into higher (n = 10; 6.3 ± 0.4) versus lower (n = 10; 3.7 ± 0.4, P exercise (all P > 0.4). Lower cardiac responders had greater leg (P = 0.027) and whole body (P = 0.03) RPE only at 185 W, but this represented a higher %peak V˙O2 in lower cardiac responders (87 ± 15% vs. 66 ± 12%, P = 0.005). Substantially lower Q˙-V˙O2 in the lower responder group did not result in altered RPE or exercising muscle deoxygenation. This suggests substantial recruitment of blood flow redistribution in the lower responder group as part of protecting matching of exercising muscle oxygen delivery to demand. © 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  11. The tripeptide feG regulates the production of intracellular reactive oxygen species by neutrophils

    Directory of Open Access Journals (Sweden)

    Davison Joseph S

    2006-06-01

    Full Text Available Abstract Background The D-isomeric form of the tripeptide FEG (feG is a potent anti-inflammatory agent that suppresses type I hypersensitivity (IgE-mediated allergic reactions in several animal species. One of feG's primary actions is to inhibit leukocyte activation resulting in loss of their adhesive and migratory properties. Since activation of neutrophils is often associated with an increase in respiratory burst with the generation of reactive oxygen species (ROS, we examined the effect of feG on the respiratory burst in neutrophils of antigen-sensitized rats. A role for protein kinase C (PKC in the actions of feG was evaluated by using selective isoform inhibitors for PKC. Results At 18h after antigen (ovalbumin challenge of sensitized Sprague-Dawley rats a pronounced neutrophilia occurred; a response that was reduced in animals treated with feG (100 μg/kg. With antigen-challenged animals the protein kinase C (PKC activator, PMA, significantly increased intracellular ROS of circulating neutrophils, as determined by flow cytometry using the fluorescent probe dihydrorhodamine-123. This increase was prevented by treatment with feG at the time of antigen challenge. The inhibitor of PKCδ, rottlerin, which effectively prevented intracellular ROS production by circulating neutrophils of animals receiving a naïve antigen, failed to inhibit PMA-stimulated ROS production if the animals were challenged with antigen. feG treatment, however, re-established the inhibitory effects of the PKCδ inhibitor on intracellular ROS production. The extracellular release of superoxide anion, evaluated by measuring the oxidative reduction of cytochrome C, was neither modified by antigen challenge nor feG treatment. However, hispidin, an inhibitor of PKCβ, inhibited the release of superoxide anion from circulating leukocytes in all groups of animals. feG prevented the increased expression of the β1-integrin CD49d on the circulating neutrophils elicited by antigen

  12. Production of reactive oxygen species from abraded silicates. Implications for the reactivity of the Martian soil

    Science.gov (United States)

    Bak, Ebbe N.; Zafirov, Kaloyan; Merrison, Jonathan P.; Jensen, Svend J. Knak; Nørnberg, Per; Gunnlaugsson, Haraldur P.; Finster, Kai

    2017-09-01

    The results of the Labeled Release and the Gas Exchange experiments conducted on Mars by the Viking Landers show that compounds in the Martian soil can cause oxidation of organics and a release of oxygen in the presence of water. Several sources have been proposed for the oxidizing compounds, but none has been validated in situ and the cause of the observed oxidation has not been resolved. In this study, laboratory simulations of saltation were conducted to examine if and under which conditions wind abrasion of silicates, a process that is common on the Martian surface, can give rise to oxidants in the form of hydrogen peroxide (H2O2) and hydroxyl radicals (ṡOH). We found that silicate samples abraded in simulated Martian atmospheres gave rise to a significant production of H2O2 and ṡOH upon contact with water. Our experiments demonstrated that abraded silicates could lead to a production of H2O2 facilitated by atmospheric O2 and inhibited by carbon dioxide. Furthermore, during simulated saltation the silicate particles became triboelectrically charged and at pressures similar to the Martian surface pressure we observed glow discharges. Electrical discharges can cause dissociation of CO2 and through subsequent reactions lead to a production of H2O2. These results indicate that the reactions linked to electrical discharges are the dominant source of H2O2 during saltation of silicates in a simulated Martian atmosphere, given the low pressure and the relatively high concentration of CO2. Our experiments provide evidence that wind driven abrasion could enhance the reactivity of the Martian soil and thereby could have contributed to the oxidation of organic compounds and the O2 release observed in the Labeled Release and the Gas Exchange experiments. Furthermore, the release of H2O2 and ṡOH from abraded silicates could have a negative effect on the persistence of organic compounds in the Martian soil and the habitability of the Martian surface.

  13. Amplifying the manganese scavenging potential of Streptococcus zooepidemicus to reactive oxygen species during production of hyaluronic acid.

    Science.gov (United States)

    Mashitah, M D; Masitah, H; Ramachandran, K B

    2004-05-01

    Streptococcus zooepidemicus (SZ) is an aerotolerant bacteria and its ability to survive under reactive oxidant challenge raises the question of the existence of a defense system. Thus growth, hyaluronic acid (HA) and hydrogen peroxide (H2O2) production by SZ in the presence of increasing concentration of Mn2+ were studied. The results suggested that the tested strain supported growth and HA production in cultures treated with 1 and 10 mM of Mn2+ regardless of H2O2 presence in the medium. This showed that SZ have acquired elaborate defense mechanisms to scavenge oxygen toxicity and thus protect cells from direct and indirect effect of this radical. In contrast, cells treated with 25 mM Mn2+ were sensitive, in which, the HA production was reduced considerably. Thus showing that the oxygen scavenger systems of the cells may be fully saturated at this concentration.

  14. Sirtuin-3 (Sirt3) regulates skeletal muscle metabolism and insulin signaling via altered mitochondrial oxidation and reactive oxygen species production

    DEFF Research Database (Denmark)

    Jing, Enxuan; Emanuelli, Brice; Hirschey, Matthew D

    2011-01-01

    Sirt3 is a member of the sirtuin family of protein deacetylases that is localized in mitochondria and regulates mitochondrial function. Sirt3 expression in skeletal muscle is decreased in models of type 1 and type 2 diabetes and regulated by feeding, fasting, and caloric restriction. Sirt3 knockout...... mice exhibit decreased oxygen consumption and develop oxidative stress in skeletal muscle, leading to JNK activation and impaired insulin signaling. This effect is mimicked by knockdown of Sirt3 in cultured myoblasts, which exhibit reduced mitochondrial oxidation, increased reactive oxygen species......, activation of JNK, increased serine and decreased tyrosine phosphorylation of IRS-1, and decreased insulin signaling. Thus, Sirt3 plays an important role in diabetes through regulation of mitochondrial oxidation, reactive oxygen species production, and insulin resistance in skeletal muscle....

  15. Fuzzy control of dissolved oxygen, pH and temperature of bubble column bioreactor for Candida utilis biomass production

    Directory of Open Access Journals (Sweden)

    Hubert Arteaga Miñano

    2012-06-01

    Full Text Available An automatic control system by dissolved oxygen (DO fuzzy logic, pH and temperature in a bubble column bioreactor (BCB for Candida utilis CECT 10704 biomass production was implemented. Their performance was compared with the classical proportional control. A data acquisition card for the control was designed, built and programmed, using the 4.14 Eagle software for the design and the 3.0 Microcode Studio Plus for programming. A program in 6.0 Visual Basic, which linked up with 7.0 MatLab for fuzzy control was developed; using Mandani inference, membership functions of input and output trapezoidal and triangular; 4 rules for the DO, 3 for pH and 3 for temperature, with connector and type and for defuzzifying the centroid method. Evaluation of biomass production was performed by determining dry weight and growth kinetics with the Gompertz model.The fuzzy control performance of DO, pH and temperature showed superiority in proportional control, characterized by a very close control to set point and a low standard deviation. DO Fuzzy control at 6 ppm, pH of 6 and 30°C, allowed to have the greatest dry weight of 7.65±0.02 g/L and the highest maximum growth of 1.51±0.2, the lowest adaptation phase of 0.27±0.01 h and the greatest specific speed of Candida utilis growth rate of 0.7±0.01 h-1.

  16. Effects of oxygen and ethanol on recombinant yeast fermentation for hepatitis B virus surface antigen production: modeling and simulation studies.

    Science.gov (United States)

    Shi, Y; Ryu, D D; Yuan, W K

    1993-01-05

    A model was formulated to examine the competitive growth of two phenotypes (Leu(+) and Leu(-)) and the product formation with recombinant Saccharomyces cerevisiae strain DBY-745, which contains the shuttle vector pYGH3-16-s with the foreign gene HBsAg (hepatitis B virus surface antigen) as well as experimental fedbatch fermentation data. The important state variables and the process parameters evaluated include (1) the ratio of the plasmid-free cell concentration to the plasmid-containing cell concentration (rho = X(-)X(+)), (2) the expression of human hepatitis B surface antigen g (CH), (3) the glucose consumption (S), (4) the ethanol production (/), (5) the change of working volume (V) in the fermentor, (6) the different specific growth rates of two phenotype cells, and (7) the plasmid loss frequency coefficient (alpha ). These variables and other parameters were carefully defined, their correlations were studied, and a mathematical model using a set of nonlinear ordinary differential equations (ODEs) for fed-batch fermentation was then obtained based on the theoretical considerations and the experimental results. The extended Kalman filter (EKF) methods was applied for the best estimate of these variables based on the experimentally observable variables: rhoV, and g (CH). Each of these variable was affected by random measuring errors under the different operating conditions. Simulation results presented for verification of the model agreed with our observations and provided useful information relevant to the operation and the control of the fedbatch recombinant yeast fermentation. The method of predicting an optimal profile of the cell growth was also demonstrated under the different dissolved oxygen concentrations.

  17. 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.

  18. Formation of nitrous oxide in a gradient of oxygenation and nitrogen loading rate during denitrification of nitrite and nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Gong, You-Kui; Peng, Yong-Zhen [School of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China); Yang, Qing, E-mail: gykren@163.com [School of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China); Wu, Wei-Min [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090 (China); Wang, Shu-Ying [School of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer The correlation of DO to N{sub 2}O emission under denitrification via nitrite was confirmed. Black-Right-Pointing-Pointer The higher nitrite ratio in NO{sub x} (nitrite and nitrate) caused the more N{sub 2}O emission. Black-Right-Pointing-Pointer Reactor feed mode and nitrite loading rate had significant impact on N{sub 2}O emission which was related to nitrite level. - Abstract: Nitrous oxide (N{sub 2}O) emission has been observed during denitrification of nitrate via nitrite as intermediate. With a laboratory-scale reactor (2.4 L), the N{sub 2}O emission was characterized under a gradient of DO concentration from 0 to 0.7 mg/L, different ratio of nitrite versus nitrate and different nitrite feed mode. The N{sub 2}O emission was influenced by the level of dissolved oxygen (DO) and nitrite accumulation. The higher DO level and the higher ratio of nitrite versus nitrate resulted in the higher N{sub 2}O emission. Using nitrite as sole electron acceptor at the same loading rate, the sequence of N{sub 2}O emission with three different feed modes was: pulse > step-wise > continuous feed. The N{sub 2}O emitted in pulse feed reactors was 3.1-4.2 and 8.2-11.7 folds of that in the step-wise feed and continuous feed reactors, respectively. With continuous feed mode, the impact of DO concentration on the mass of N{sub 2}O emitted was limited while the higher N{sub 2}O emission occurred at the higher nitrite loading rate.

  19. Pentose Phosphate Shunt Modulates Reactive Oxygen Species and Nitric Oxide Production Controlling Trypanosoma cruzi in Macrophages

    Directory of Open Access Journals (Sweden)

    Sue-jie Koo

    2018-02-01

    Full Text Available Metabolism provides substrates for reactive oxygen species (ROS and nitric oxide (NO generation, which are a part of the macrophage (Mφ anti-microbial response. Mφs infected with Trypanosoma cruzi (Tc produce insufficient levels of oxidative species and lower levels of glycolysis compared to classical Mφs. How Mφs fail to elicit a potent ROS/NO response during infection and its link to glycolysis is unknown. Herein, we evaluated for ROS, NO, and cytokine production in the presence of metabolic modulators of glycolysis and the Krebs cycle. Metabolic status was analyzed by Seahorse Flux Analyzer and mass spectrometry and validated by RNAi. Tc infection of RAW264.7 or bone marrow-derived Mφs elicited a substantial increase in peroxisome proliferator-activated receptor (PPAR-α expression and pro-inflammatory cytokine release, and moderate levels of ROS/NO by 18 h. Interferon (IFN-γ addition enhanced the Tc-induced ROS/NO release and shut down mitochondrial respiration to the levels noted in classical Mφs. Inhibition of PPAR-α attenuated the ROS/NO response and was insufficient for complete metabolic shift. Deprivation of glucose and inhibition of pyruvate transport showed that Krebs cycle and glycolysis support ROS/NO generation in Tc + IFN-γ stimulated Mφs. Metabolic profiling and RNAi studies showed that glycolysis-pentose phosphate pathway (PPP at 6-phosphogluconate dehydrogenase was essential for ROS/NO response and control of parasite replication in Mφ. We conclude that IFN-γ, but not inhibition of PPAR-α, supports metabolic upregulation of glycolytic-PPP for eliciting potent ROS/NO response in Tc-infected Mφs. Chemical analogs enhancing the glucose-PPP will be beneficial in controlling Tc replication and dissemination by Mφs.

  20. Enhanced Production of carboxymethylcellulase by a marine bacterium, Bacillus velezensis A-68, by using rice hulls in pilot-scale bioreactor under optimized conditions for dissolved oxygen.

    Science.gov (United States)

    Gao, Wa; Kim, Hye-Jin; Chung, Chung-Han; Lee, Jin-Woo

    2014-09-01

    The optimal conditions for the production of carboxymethylcellulase (CMCase) by Bacillus velezensis A-68 at a flask scale have been previously reported. In this study, the parameters involved in dissolved oxygen in 7 and 100 L bioreactors were optimized for the pilot-scale production of CMCase. The optimal agitation speed and aeration rate for cell growth of B. velezensis A-68 were 323 rpm and 1.46 vvm in a 7 L bioreactor, whereas those for the production of CMCase were 380 rpm and 0.54 vvm, respectively. The analysis of variance (ANOVA) implied that the highly significant factor for cell growth was the aeration rate, whereas that for the production of CMCase was the agitation speed. The optimal inner pressures for cell growth and the production of CMCase by B. velezensis A-68 in a 100 L bioreactor were 0.00 and 0.04 MPa, respectively. The maximal production of CMCase in a 100 L bioreactor under optimized conditions using rice hulls was 108.1 U/ml, which was 1.8 times higher than that at a flask scale under previously optimized conditions.

  1. Effects of levosimendan on glomerular filtration rate, renal blood flow, and renal oxygenation after cardiac surgery with cardiopulmonary bypass: a randomized placebo-controlled study.

    Science.gov (United States)

    Bragadottir, Gudrun; Redfors, Bengt; Ricksten, Sven-Erik

    2013-10-01

    Acute kidney injury develops in a large proportion of patients after cardiac surgery because of the low cardiac output syndrome. The inodilator levosimendan increases cardiac output after cardiac surgery with cardiopulmonary bypass, but a detailed analysis of its effects on renal perfusion, glomerular filtration, and renal oxygenation in this group of patients is lacking. We therefore evaluated the effects of levosimendan on renal blood flow, glomerular filtration rate, renal oxygen consumption, and renal oxygen demand/supply relationship, i.e., renal oxygen extraction, early after cardiac surgery with cardiopulmonary bypass. Prospective, placebo-controlled, and randomized trial. Cardiothoracic ICU of a tertiary center. Postcardiac surgery patients (n=30). The patients were randomized to receive levosimendan, 0.1 µg/kg/min after a loading dose of 12 µg/kg (n=15), or placebo (n=15). The experimental procedure started 4-6 hours after surgery in the ICU during propofol sedation and mechanical ventilation. Systemic hemodynamic were evaluated by a pulmonary artery thermodilution catheter. Renal blood flow and glomerular filtration rate were measured by the renal vein retrograde thermodilution technique and by renal extraction of Cr-EDTA, respectively. Central venous pressure was kept constant by colloid/crystalloid infusion. Compared to placebo, levosimendan increased cardiac index (22%), stroke volume index (15%), and heart rate (7%) and decreased systemic vascular resistance index (21%), whereas mean arterial pressure was not affected. Levosimendan induced significant increases in renal blood flow (12%, prenal vascular resistance (18%, prenal oxygen consumption, or renal oxygen extraction, compared to placebo. After cardiac surgery with cardiopulmonary bypass, levosimendan induces a vasodilation, preferentially of preglomerular resistance vessels, increasing both renal blood flow and glomerular filtration rate without jeopardizing renal oxygenation. Due to its

  2. 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.

  3. Oxygen vacancy rich Cu2O based composite material with nitrogen doped carbon as matrix for photocatalytic H2 production and organic pollutant removal.

    Science.gov (United States)

    Lu, Lele; Xu, Xinxin; Yan, Jiaming; Shi, Fa-Nian; Huo, Yuqiu

    2018-02-06

    A nitrogen doped carbon matrix supported Cu 2 O composite material (Cu/Cu2O@NC) was fabricated successfully with a coordination polymer as precursor through calcination. In this composite material, Cu 2 O particles with a size of about 6-10 nm were dispersed evenly in the nitrogen doped carbon matrix. After calcination, some coordinated nitrogen atoms were doped in the lattice of Cu 2 O and replace oxygen atoms, thus generating a large number of oxygen vacancies. In Cu/Cu2O@NC, the existence of oxygen vacancies has been confirmed by electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS). Under visible light irradiation, Cu/Cu2O@NC exhibits excellent H 2 production with the rate of 379.6 μmol h -1 g -1 . Its photocatalytic activity affects organic dyes, such as Rhodamine B (RhB) and methyl orange (MO). In addition to photocatalysis, Cu/Cu2O@NC also exhibits striking catalytic activity in reductive conversion of 4-nitrophenol to 4-aminophenol with in presence of sodium borohydride (NaBH 4 ). The conversion efficiency reaches almost 100% in 250 s with the quantity of Cu/Cu2O@NC as low as 5 mg. The outstanding H 2 production and organic pollutants removal are attributed to the oxygen vacancy. We expect that Cu/Cu2O@NC will find its way as a new resource for hydrogen energy as well as a promising material in water purification.

  4. Electrolyte Engineering Toward Efficient Hydrogen Production Electrocatalysis with Oxygen-crossover Regulation under Densely Buffered Near-neutral pH Conditions

    KAUST Repository

    Shinagawa, Tatsuya; Takanabe, Kazuhiro

    2015-01-01

    This study tackles the core issues associated with near-neutral pH water splitting, particularly regarding electrolyte engineering in the electrocatalysis and product cross-over. We demonstrate that solute engineering has a major impact on water splitting electrocatalysis because the diffusion component, often not well integrated into performance descriptions, largely determines the overall performance. The hydrogen evolution reaction (HER) was investigated on Pt, Ni and NiMo catalysts in various concentrations of cations (Li+, K+, Na+) and anions (H2PO4−, HPO42−, PO43− and HCO3−) to describe its performance by quantifying kinetics, diffusion and solution resistance. In fact, the choice of electrolyte in terms of its identity and activity drastically altered the HER rate and oxygen mass-transport flux at near-neutral pH. Electrolyte properties (activity coefficient, kinematic viscosity and diffusion coefficient) accurately described the diffusion contribution, which can be easily isolated when a highly active Pt catalyst was used for the HER. By analyzing these properties, we maximized the HER rate on the Pt by tuning the solute concentration (typically 1.5 – 2.0 M). Moreover, the kinematic viscosity and oxygen solubility in such densely buffered conditions governed the oxygen mass-transport flux in the electrolyte, which in turn tuned the cross-over flux. At near-neutral pH, as high as 90 % selectivity toward the HER was achieved even under an oxygen saturated condition, where only a 40 mV overpotential was needed to achieve 10 mA cm−2 for the HER. This information can be regarded as an important milestone for achieving a highly efficient water splitting system at near-neutral pH.

  5. Electrolyte Engineering Toward Efficient Hydrogen Production Electrocatalysis with Oxygen-crossover Regulation under Densely Buffered Near-neutral pH Conditions

    KAUST Repository

    Shinagawa, Tatsuya

    2015-12-30

    This study tackles the core issues associated with near-neutral pH water splitting, particularly regarding electrolyte engineering in the electrocatalysis and product cross-over. We demonstrate that solute engineering has a major impact on water splitting electrocatalysis because the diffusion component, often not well integrated into performance descriptions, largely determines the overall performance. The hydrogen evolution reaction (HER) was investigated on Pt, Ni and NiMo catalysts in various concentrations of cations (Li+, K+, Na+) and anions (H2PO4−, HPO42−, PO43− and HCO3−) to describe its performance by quantifying kinetics, diffusion and solution resistance. In fact, the choice of electrolyte in terms of its identity and activity drastically altered the HER rate and oxygen mass-transport flux at near-neutral pH. Electrolyte properties (activity coefficient, kinematic viscosity and diffusion coefficient) accurately described the diffusion contribution, which can be easily isolated when a highly active Pt catalyst was used for the HER. By analyzing these properties, we maximized the HER rate on the Pt by tuning the solute concentration (typically 1.5 – 2.0 M). Moreover, the kinematic viscosity and oxygen solubility in such densely buffered conditions governed the oxygen mass-transport flux in the electrolyte, which in turn tuned the cross-over flux. At near-neutral pH, as high as 90 % selectivity toward the HER was achieved even under an oxygen saturated condition, where only a 40 mV overpotential was needed to achieve 10 mA cm−2 for the HER. This information can be regarded as an important milestone for achieving a highly efficient water splitting system at near-neutral pH.

  6. Latitudinal variations in intermediate depth ventilation and biological production over northeastern Pacific Oxygen Minimum Zones during the last 60 ka

    Science.gov (United States)

    Cartapanis, Olivier; Tachikawa, Kazuyo; Bard, Edouard

    2012-10-01

    Mechanisms affecting past variability in the Oxygen Minimum Zone (OMZ) in the Eastern Tropical North Pacific (ETNP) are poorly known. We analyzed core MD02-2524, obtained from the Nicaragua Margin in the present ETNP OMZ for major and minor elements (titanium (Ti), brome (Br), silicon (Si), potassium (K), and calcium (Ca)) using an X-ray Fluorescence (XRF) core scanner, and redox-sensitive trace elements (uranium (U), molybdenum (Mo), and nickel (Ni)) determined by ICP-MS. The U and Mo content was higher during the deglaciation than during the Holocene and the last glacial maximum, whereas enrichment was not observed for Ni, an element closely associated with organic matter. High-resolution XRF scanning indicated that the Ca-based carbonate content had millennial-scale variability inversely correlated with Br-based organic matter and Si/K-based opal content during the last glacial period. The available data suggest no clear regional trend in biological productivity during the last deglaciation, but significant local variability in the coastal eastern equatorial Pacific. The trace element enrichment and the lack of a concomitant increase in biogenic phases indicated that an enhanced ETNP OMZ, at least between 15°N and 12°N at a water depth of 500-900 m, was principally caused by a reduced oxygen supply driven by oceanic circulation to the Nicaragua Basin during the deglaciation. The observed patterns can be interpreted as the distinct changes in the oxygenation state of northern and southern water masses at intermediate depths. We also found evidence for a decoupling between local productivity and pore water oxygenation for several millennial-scale events during Marine Isotopic Stage 3, indicating that remote oxygen consumption and/or oceanic ventilation impacted OMZ intensity. Multi-millennial scale variations of the productivity at Papagayo upwelling cell displayed an opposite trend from productivity at the Costa Rica Dome, in relation with the latitudinal shift

  7. A multiplexed electronic architecture for opto-electronic patch sensor to effectively monitor heart rate and oxygen saturation

    Science.gov (United States)

    Yan, Liangwen; Hu, Sijung; Alharbi, Samah; Blanos, Panagiotis

    2018-02-01

    To effectively capture human vital signs, a multi-wavelength optoelectronic patch sensor (MOEPS), together with a schematic architecture of electronics, was developed to overcome the drawbacks of present photoplethysmographic (PPG) sensors. To obtain a better performance of in vivo physiological measurement, the optimal illuminations, i.e., light emitting diodes (LEDs) in the MOEPS, whose wavelength is automatically adjusted to each specific subject, were selected to capture better PPG signals. A multiplexed electronic architecture has been well established to properly drive the MOEPS and effectively capture pulsatile waveforms at rest. The protocol was designed to investigate its performance with the participation of 11 healthy subjects aged between 18 and 30. The signals obtained from green (525nm) and orange (595nm) illuminations were used to extract heart rate (HR) and oxygen saturation (SpO2%). These results were compared with data, simultaneously acquired, from a commercial ECG and a pulse oximeter. Considering the difficulty for current devices to attain the SpO2%, a new computing method, to obtain the value of SpO2%, is proposed depended on the green and orange wavelength illuminations. The values of SpO2% between the MOEPS and the commercial Pulse Oximeter devics showed that the results were in good agreement. The values of HR showed close correlation between commercial devices and the MOEPS (HR: r1=0.994(Green); r2=0.992(Orange); r3=0.975(Red); r4=0.990(IR)).

  8. Effect of membranes on oxygen transfer rate and consumption within a newly developed three-compartment bioartificial liver device: Advanced experimental and theoretical studies.

    Science.gov (United States)

    Hilal-Alnaqbi, Ali; Mourad, Abdel-Hamid I; Yousef, Basem F

    2014-01-01

    A mathematical model is developed to predict oxygen transfer in the fiber-in-fiber (FIF) bioartificial liver device. The model parameters are taken from the constructed and tested FIF modules. We extended the Krogh cylinder model by including one more zone for oxygen transfer. Cellular oxygen uptake was based on Michaelis-Menten kinetics. The effect of varying a number of important model parameters is investigated, including (1) oxygen partial pressure at the inlet, (2) the hydraulic permeability of compartment B (cell region), (3) the hydraulic permeability of the inner membrane, and (4) the oxygen diffusivity of the outer membrane. The mathematical model is validated by comparing its output against the experimentally acquired values of an oxygen transfer rate and the hydrostatic pressure drop. Three governing simultaneous linear differential equations are derived to predict and validate the experimental measurements, e.g., the flow rate and the hydrostatic pressure drop. The model output simulated the experimental measurements to a high degree of accuracy. The model predictions show that the cells in the annulus can be oxygenated well even at high cell density or at a low level of gas phase PG if the value of the oxygen diffusion coefficient Dm is 16 × 10(-5) . The mathematical model also shows that the performance of the FIF improves by increasing the permeability of polypropylene membrane (inner fiber). Moreover, the model predicted that 60% of plasma has access to the cells in the annulus within the first 10% of the FIF bioreactor axial length for a specific polypropylene membrane permeability and can reach 95% within the first 30% of its axial length. © 2013 International Union of Biochemistry and Molecular Biology, Inc.

  9. Reply to Nicholson's comment on "Consistent calculation of aquatic gross production from oxygen triple isotope measurements" by Kaiser (2011

    Directory of Open Access Journals (Sweden)

    J. Kaiser

    2012-08-01

    Full Text Available The comment by Nicholson (2011a questions the "consistency" of the "definition" of the "biological end-member" used by Kaiser (2011a in the calculation of oxygen gross production. "Biological end-member" refers to the relative oxygen isotope ratio difference between photosynthetic oxygen and Air-O2 (abbreviated 17δP and 18δP for 17O/16O and 18O/16O, respectively. The comment claims that this leads to an overestimate of the discrepancy between previous studies and that the resulting gross production rates are "30% too high". Nicholson recognises the improved accuracy of Kaiser's direct calculation ("dual-delta" method compared to previous approximate approaches based on 17O excess (17Δ and its simplicity compared to previous iterative calculation methods. Although he correctly points out that differences in the normalised gross production rate (g are largely due to different input parameters used in Kaiser's "base case" and previous studies, he does not acknowledge Kaiser's observation that iterative and dual-delta calculation methods give exactly the same g for the same input parameters (disregarding kinetic isotope fractionation during air-sea exchange. The comment is based on misunderstandings with respect to the "base case" 17δP and 18δP values. Since direct measurements of 17δP and 18δPdo not exist or have been lost, Kaiser constructed the "base case" in a way that was consistent and compatible with literature data. Nicholson showed that an alternative reconstruction of 17δP gives g values closer to previous studies. However, unlike Nicholson, we refrain from interpreting either reconstruction as a benchmark for the accuracy of g. A number of publications over the last 12 months

  10. Nutrient utilization and oxygen production by Chlorella Vulgaris in a hybrid membrane bioreactor and algal membrane photobioreactor system

    KAUST Repository

    Najm, Yasmeen Hani Kamal

    2017-02-17

    This work studied oxygen production and nutrient utilization by Chlorella Vulgaris at different organic/inorganic carbon (OC/IC) and ammonium/nitrate (NH4+-N/NO3--N) ratios to design a hybrid aerobic membrane bioreactor (MBR) and membrane photobioreactor (MPBR) system. Specific oxygen production by C. vulgaris was enough to support the MBR if high growth is accomplished. Nearly 100% removal (or utilization) of PO43--P and IC was achieved under all conditions tested. Optimal growth was achieved at mixotrophic carbon conditions (0.353 d-1) and the highest NH4+-N concentration (0.357 d-1), with preferable NH4+-N utilization rather than NO3--N. The results indicate the potential of alternative process designs to treat domestic wastewater by coupling the hybrid MBR - MPBR systems.

  11. Nutrient utilization and oxygen production by Chlorella Vulgaris in a hybrid membrane bioreactor and algal membrane photobioreactor system

    KAUST Repository

    Najm, Yasmeen Hani Kamal; Jeong, Sanghyun; Leiknes, TorOve

    2017-01-01

    This work studied oxygen production and nutrient utilization by Chlorella Vulgaris at different organic/inorganic carbon (OC/IC) and ammonium/nitrate (NH4+-N/NO3--N) ratios to design a hybrid aerobic membrane bioreactor (MBR) and membrane photobioreactor (MPBR) system. Specific oxygen production by C. vulgaris was enough to support the MBR if high growth is accomplished. Nearly 100% removal (or utilization) of PO43--P and IC was achieved under all conditions tested. Optimal growth was achieved at mixotrophic carbon conditions (0.353 d-1) and the highest NH4+-N concentration (0.357 d-1), with preferable NH4+-N utilization rather than NO3--N. The results indicate the potential of alternative process designs to treat domestic wastewater by coupling the hybrid MBR - MPBR systems.

  12. Event-Associated Oxygen Consumption Rate Increases ca. Five-Fold When Interictal Activity Transforms into Seizure-Like Events In Vitro

    Directory of Open Access Journals (Sweden)

    Karl Schoknecht

    2017-09-01

    Full Text Available Neuronal injury due to seizures may result from a mismatch of energy demand and adenosine triphosphate (ATP synthesis. However, ATP demand and oxygen consumption rates have not been accurately determined, yet, for different patterns of epileptic activity, such as interictal and ictal events. We studied interictal-like and seizure-like epileptiform activity induced by the GABAA antagonist bicuculline alone, and with co-application of the M-current blocker XE-991, in rat hippocampal slices. Metabolic changes were investigated based on recording partial oxygen pressure, extracellular potassium concentration, and intracellular flavine adenine dinucleotide (FAD redox potential. Recorded data were used to calculate oxygen consumption and relative ATP consumption rates, cellular ATP depletion, and changes in FAD/FADH2 ratio by applying a reactive-diffusion and a two compartment metabolic model. Oxygen-consumption rates were ca. five times higher during seizure activity than interictal activity. Additionally, ATP consumption was higher during seizure activity (~94% above control than interictal activity (~15% above control. Modeling of FAD transients based on partial pressure of oxygen recordings confirmed increased energy demand during both seizure and interictal activity and predicted actual FAD autofluorescence recordings, thereby validating the model. Quantifying metabolic alterations during epileptiform activity has translational relevance as it may help to understand the contribution of energy supply and demand mismatches to seizure-induced injury.

  13. Engineering Ralstonia eutropha for Production of Isobutanol (IBT) Motor Fuel from Carbon Dioxide, Hydrogen, and Oxygen Project Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Sinskey, Anthony J. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Worden, Robert Mark [Michigan State Univ., East Lansing, MI (United States); Brigham, Christopher [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Lu, Jingnan [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Quimby, John Westlake [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Gai, Claudia [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Speth, Daan [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Elliott, Sean [Boston Univ., MA (United States); Fei, John Qiang [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Bernardi, Amanda [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Li, Sophia [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Grunwald, Stephan [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Grousseau, Estelle [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Maiti, Soumen [Michigan State Univ., East Lansing, MI (United States); Liu, Chole [Michigan State Univ., East Lansing, MI (United States)

    2013-12-16

    E), the production titer of the improved to 270 mg/L isobutanol and 40 mg/L 3-methyl-1-butanol. Semicontinuous flask cultivation supplied the cells with sufficient nutrients while minimizing the toxicity caused by isobutanol. Under this cultivation, the R. eutropha mutant grew and produced more than 14 g/L branched-chain alcohols over the duration of 50 days. These results demonstrate that R. eutropha carbon flux can be redirected from PHB to branched-chain alcohols and that engineered R. eutropha can be cultivated over prolonged periods of time for product biosynthesis. While this bioengineering work was being done at the Sinskey laboratory at MIT, the researchers at the Worden laboratory at Michigan State were working on the design and construction of the required specialty bioreactor for incompatible gasses (BIG) that would allow the safe feeding of microbes on Carbon Dioxide, Hydrogen, and Oxygen without explosive results. The early design and assembly work in year 1 incorporated a novel microbubble generator to maximize the bioavailability of gasses within the system comprised of small scale hollow fiber reactors. The early success of the microbubble generator eliminated the need to investigate potentially toxic surfactants within the system. For operational control, the system design incorporated a Opto22-based control network. The researchers also selected the specific hollow fiber material suitable for the bioreactor application. A variety of commercially available hollow fiber membranes were compared with regard to their pore sizes, cell affinity, and potential interference to cell viability assays. The selected membrane with its spongy layer was then tested for diffusivity of O2 and CO2. The instrumented system was then fully assembled for experimentally measuring the heterotrophic growth rate of immobilized R. eutropha cells. The requisite procedures for inoculation, measurement, and cleaning were established enabling the system performance to be validated

  14. System analysis of dry black liquor gasification based synthetic gas production comparing oxygen and air blown gasification systems

    International Nuclear Information System (INIS)

    Naqvi, Muhammad; Yan, Jinyue; Dahlquist, Erik

    2013-01-01

    Highlights: ► Circulating fluidized bed system for black liquor gasification with direct causticization. ► Effects of gasifying medium i.e. oxygen or air, on gasification are studied. ► Direct causticization eliminates energy intensive limekiln reducing biomass use. ► Results show 10% higher SNG production from O 2 blown system than air blown system. ► SNG production is higher in O 2 blown system than air blown system. - Abstract: The black liquor gasification based bio-fuel production at chemical pulp mill is an attractive option to replace conventional recovery boilers increasing system energy efficiency. The present paper studies circulating fluidized bed system with direct causticization using TiO 2 for the gasification of the black liquor to the synthesis gas. The advantage of using direct causticization is the elimination of energy-intensive lime kiln which is an integral part of the conventional black liquor recovery system. The study evaluates the effects of gasifying medium i.e. oxygen or air, on the fluidized bed gasification system, the synthesis gas composition, and the downstream processes for the synthesis gas conversion to the synthetic natural gas (SNG). The results showed higher synthetic natural gas production potential with about 10% higher energy efficiency using oxygen blown gasification system than the air blown system. From the pulp mill integration perspective, the material and energy balance results in better integration of air blown system than the oxygen blown system, e.g. less steam required to be generated in the power boiler, less electricity import, and less additional biomass requirement. However, the air blown system still requires a significant amount of energy in terms of the synthesis gas handling and gas upgrading using the nitrogen rejection system

  15. The role of iron and reactive oxygen species in the production of CO2 in arctic soil waters

    Science.gov (United States)

    Trusiak, Adrianna; Treibergs, Lija A.; Kling, George W.; Cory, Rose M.

    2018-03-01

    Hydroxyl radical (radOH) is a highly reactive oxidant of dissolved organic carbon (DOC) in the environment. radOH production in the dark was observed through iron and DOC mediated Fenton reactions in natural environments. Specifically, when dissolved oxygen (O2) was added to low oxygen and anoxic soil waters in arctic Alaska, radOH was produced in proportion to the concentrations of reduced iron (Fe(II)) and DOC. Here we demonstrate that Fe(II) was the main electron donor to O2 to produce radOH. In addition to quantifying radOH production, hydrogen peroxide (H2O2) was detected in soil waters as a likely intermediate in radOH production from oxidation of Fe(II). For the first time in natural systems we detected carbon dioxide (CO2) production from radOH oxidation of DOC. More than half of the arctic soil waters tested showed production of CO2 under conditions conducive for production of radOH. Findings from this study strongly suggest that DOC is the main sink for radOH, and that radOH can oxidize DOC to yield CO2. Thus, this iron-mediated, dark chemical oxidation of DOC may be an important component of the arctic carbon cycle.

  16. Using rating to evaluate quality of peanut products | Ogunsanwo ...

    African Journals Online (AJOL)

    Peanuts seeds roasted at 140°C for 40 min for either 25 or 35 min were rated to be of comparable quality with locally available commercial samples. Peanut butter prepared from seeds roasted at160°C for 30 min was also rated to be comparable with commercial samples, while Kwulinkwulis from seeds dry roasted at 150°C ...

  17. Vagal activity and oxygen saturation response to hypoxia: Effects of aerobic fitness and rating of hypoxia tolerance

    Directory of Open Access Journals (Sweden)

    Tomáš Macoun

    2017-10-01

    Full Text Available Background: A reduction in the inspired oxygen fraction (FiO2 induces a decline in arterial oxygen saturation (SpO2 and changes of heart rate variability (HRV. It has been shown that SpO2 and HRV responses to similar levels of acute normobaric hypoxia are inter-individual variable. Variable response may be influenced by normoxia reached maximal oxygen uptake (VO2max value. Objective: The primary aim was to assess HRV and the SpO2 response to hypoxia, and examine the association with normoxic VO2max. Methods: Supine HRV and SpO2 were monitored during normobaric hypoxia (FiO2 = 9.6% for 10 minutes in 28 subjects, aged 23.7 ± 1.7 years. HRV was evaluated by using both spectral and time domain HRV analysis. Low frequency (LF, 0.05-0.15 Hz and high frequency (HF, 0.15-0.50 Hz power together with square root of the mean of the squares of the successive differences (rMSSD were calculated and transformed by natural logarithm (Ln. Based on the SpO2 in hypoxia, subjects were divided into Resistant (RG, SpO2 ≥ 70.9%, n = 14 and Sensitive (SG, SpO2 < 70.9%, n = 14 groups. Perceived hypoxia tolerance was self-scored on a 4-level scale. Results: VO2max was higher in SG (62.4 ± 7.2 ml ⋅ kg-1 ⋅ min-1 compared with RG (55.5 ± 7.1 ml ⋅ kg-1 ⋅ min-1, p = .017, d = 0.97. A significant relationship (r = -.45, p = .017 between hypoxic-normoxic difference in SpO2 and normoxic VO2max level was found. Vagal activity (Ln rMSSD was significantly decreased (SG: p < .001, d = 2.64; RG: p < .001, d = 1.22, while sympathetic activity (Ln LF/HF was relatively increased (p < .001, d = -1.40 in only the SG during hypoxia. Conclusions: Results show that subjects with a higher aerobic capacity exhibited a greater decline in SpO2, accompanied by greater autonomic cardiac disturbances during hypoxia. The SpO2 reduction was associated with perceived hypoxia comfort/discomfort. The hypoxia

  18. Plasma reactive oxygen metabolites and non-enzymatic antioxidant capacity are not affected by an acute increase of metabolic rate in zebra finches

    NARCIS (Netherlands)

    Beamonte Barrientos, Rene; Verhulst, Simon

    Understanding the sources of variation in oxidative stress level is a challenging issue due to the implications of oxidative stress for late age diseases, longevity and life-history trade-offs. Reactive oxygen species that cause oxidative stress are mostly a by-product of energy metabolism and it is

  19. Oxygen concentration inside a functioning photosynthetic cell.

    Science.gov (United States)

    Kihara, Shigeharu; Hartzler, Daniel A; Savikhin, Sergei

    2014-05-06

    The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic photosynthetic bacteria in solitary form could have evolved ∼2.8 billion years ago without special mechanisms to protect them against reactive oxygen species. These mechanisms instead could have been developed during the following ∼500 million years while the oxygen level in the Earth's atmosphere was slowly rising. Excess oxygen concentrations within individual cells of the apomorphic cyanobacteria Synechocystis and Synechococcus are 0.064 and 0.25 μM, respectively. These numbers suggest that intramembrane and intracellular proteins in isolated oxygenic photosynthetic cells are not subjected to excessively high oxygen levels. The situation is different for closely packed colonies of photosynthetic cells. Calculations show that the excess concentration within colonies that are ∼40 μm or larger in diameter can be comparable to the oxygen concentration in air-saturated water, suggesting that species forming colonies require protection against reactive oxygen species even in the absence of oxygen in the surrounding atmosphere. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  20. Radio-frequency wave enhanced runaway production rate

    International Nuclear Information System (INIS)

    Chan, V.S.; McClain, F.W.

    1983-01-01

    Enhancement of runaway electron production (over that of an Ohmic discharge) can be achieved by the addition of radio-frequency waves. This effect is studied analytically and numerically using a two-dimensional Fokker--Planck quasilinear equation

  1. Effect of oxygen level on the oxidative stability of two different retail pork products stored using modified atmosphere packaging (MAP)

    DEFF Research Database (Denmark)

    Spanos, Dimitrios; Ann Tørngren, Mari; Christensen, Mette

    2016-01-01

    The characteristics and the oxidative stability of pork steaks and of pork mince were investigated during 2, 5 and 7 days of refrigerated storage using oxygen (O2) levels of 0%, 20%, 50% and 80% in modified atmosphere packaging (MAP). Steaks stored during 7 days were not affected by an increase i......%) O2 MAP. The results show that fresh pork products are affected differently by the MAP O2 concentration and strongly indicate that optimisation of MAP based on the retail product type would be of considerable benefit to their oxidative stability....

  2. Hedging endowment assurance products under interest rate and mortality risk

    NARCIS (Netherlands)

    Chen, A.; Mahayni, A.

    2007-01-01

    This paper analyzes how model misspecification associated with both interest rate and mortality risk influences hedging decisions of insurance companies. For this purpose, diverse risk management strategies which are riskminimizing when model risk is ignored come into consideration. The

  3. Numerical investigation of a non-aqueous lithium-oxygen battery based on lithium superoxide as the discharge product

    International Nuclear Information System (INIS)

    Tan, Peng; Ni, Meng; Shao, Zongping; Chen, Bin; Kong, Wei

    2017-01-01

    Highlights: •A macroscopic model for Li-O 2 batteries based on LiO 2 is developed. •The electrode and electrolyte properties on discharge behaviors are investigated. •A thin cathode with a large porosity is favorable for a high specific capacity. •A high catalytic activity can lead to a high discharge voltage. •The oxygen solubility has larger impacts on the discharge performance. -- Abstract: It is reported lithium superoxide as the discharge product can largely decrease the charge voltage and enable a high round-trip efficiency of lithium-oxygen (Li-O 2 ) batteries. Here, we conduct a numerical investigation of the discharge behaviors of such batteries with LiO 2 as the discharge product. A mathematical model considering the mass transport and electrochemical reaction processes is first developed, which gives good agreement of the simulated discharge voltage with the experimental data. Then, with this model, the effects of electrode and electrolyte properties on the discharge performance are detailedly investigated. It is found that a thin cathode with a large porosity is favorable for a high specific capacity, and a high catalytic activity can lead to a high discharge voltage. For the cathode with different geometrical properties, it is found that the oxygen solubility and diffusivity have similar impacts on discharge capacities, but the oxygen solubility has a larger impact on energy densities. Besides, the limitations and further developments of the present model are also discussed. The results obtained from this work may give useful guidance for the discharge performance improvements of non-aqueous Li-O 2 batteries, and provide implications for other energy storage systems with solid product formation such as Na-O 2 batteries and Li-S batteries.

  4. Mechanisms of electron transfer from structrual Fe(II) in reduced nontronite to oxygen for production of hydroxyl radicals

    Science.gov (United States)

    Yuan, Songhu; Liu, Xixiang; Liao, Wenjuan; Zhang, Peng; Wang, Xiaoming; Tong, Man

    2018-02-01

    Production of hydroxyl radicals (radOH) has been recently revealed upon oxygenation of sediments in redox-dynamic subsurface environments. In particular, Fe(II)-bearing clay minerals are the major sediment components contributing to radOH production upon oxygenation, and the produced radOH can oxidize contaminants and inactivate bacteria. Whereas, the mechanisms of radOH production from oxygenation of Fe(II)-bearing clay minerals remain elusive. The objectives of this study were to identify the structural variation of Fe(II) entities during the oxidation of Fe(II)-bearing clay minerals by O2, and to unravel the mechanisms of electron transfer within the mineral structure and from mineral to O2 for radOH production. Nontronite (NAu-2, 23% Fe) which was chemically reduced to 54.5% Fe(II) in total Fe was used as a model Fe(II)-bearing clay mineral. Production of radOH and oxidation of Fe(II) were measured during the oxidation of reduced NAu-2 by O2. A wide spectrum of spectroscopic techniques, including Fourier transform infrared spectroscopy (FTIR), Fe K-edge X-ray absorption spectroscopy (XAS), Mössbauer spectra, and X-ray photoelectron spectroscopy (XPS), were employed to explore the structural variation of Fe(II) entities in NAu-2 and the electron transfer within NAu-2 and from NAu-2 to O2. For 180 min oxidation of 1 g/L reduced NAu-2, a biphasic radOH production was observed, being quick within the initial 15 min and slow afterwards. Production of radOH correlates well with oxidation of Fe(II) in the reduced NAu-2. Within the initial 15 min, trioctahedral Fe(II)-Fe(II)-Fe(II) entities and edge Fe(II) in the reduced NAu-2 were preferentially and quickly oxidized, and electrons from the interior Fe(II)-Fe(II)-Fe(II) entities were most likely ejected from the basal siloxane plane to O2. Meanwhile, trioctahedral Fe(II)-Fe(II)-Fe(II) entities were mainly transformed to dioctahedral Fe(II)-Fe(II) entities. When the time of oxygenation was longer than 15 min

  5. One hour effects of salbutamol and formoterol on blood pressure, heart rate and oxygen saturation in asthmatics

    Directory of Open Access Journals (Sweden)

    Geraldo Andrade Capuchinho-Júnior

    2008-05-01

    Full Text Available Aim: To analyse systolic (SBP and diastolic blood pressure (DBP, partial oxygen saturation (SpO2 and heart rate (HR disorders for an hour after short and long acting ß2-agonists. Material and methods: Twenty-four severe persistent asthma Pulmonology outpatients at Hospital Universitario Gaffree e Guinle were selected. SBP, DBP, SpO2 and HR values were determined before and after 400 μg of salbutamol and 12 μg of formoterol, on different days, with a minimum interval of 24 hours. Results: All patients showed ventilatory obstruction, as seen by a reduced FEV1/FVC ratio. There was no statistical SBP/DBP/HR difference after bronchodilator agents, but SpO2 increased with salbutamol. Conclusion: A standard dose of salbutamol and formoterol does not cause haemodynamic disorder. Resumo: Objectivo: Analisar os possíveis efeitos do uso de β-2-agonistas, de curta e longa duração, nas pressões arteriais sistólica (PAS e diastólica (PAD, na saturação parcial de oxigénio (SpO2 e na frequência cardíaca (FC, durante o período de uma hora. Material e métodos: Vinte e quatro doentes com asma persistente grave, em tratamento no ambulatório de Pneumologia do Hospital Universitário Gaffrée e Guinle, foram seleccionados para um ensaio clínico sequencial e cruzado. Os valores da PAS, PAD, SpO2 e FC foram registados antes e após o uso de broncodilatadores, salbutamol 400 μg e formoterol 12 μg, em dias diferentes, com intervalo mínimo de 24 horas. Resultados: Todos os doentes apresentaram distúrbio ventilatório obstrutivo, identificado pela redução da relação entre o volume expiratório forçado no primeiro segundo (VEMS e a capacidade vital forçada (CVF. Após o uso de substância broncodilatadora, não houve variação significativa nas PAS e PAD, nem na FC; porém, a SpO2 aumentou com o uso de salbutamol. Conclusão: Não foram observadas

  6. Maximum Plant Uptakes for Water, Nutrients, and Oxygen Are Not Always Met by Irrigation Rate and Distribution in Water-based Cultivation Systems.

    Science.gov (United States)

    Blok, Chris; Jackson, Brian E; Guo, Xianfeng; de Visser, Pieter H B; Marcelis, Leo F M

    2017-01-01

    Growing on rooting media other than soils in situ -i.e., substrate-based growing- allows for higher yields than soil-based growing as transport rates of water, nutrients, and oxygen in substrate surpass those in soil. Possibly water-based growing allows for even higher yields as transport rates of water and nutrients in water surpass those in substrate, even though the transport of oxygen may be more complex. Transport rates can only limit growth when they are below a rate corresponding to maximum plant uptake. Our first objective was to compare Chrysanthemum growth performance for three water-based growing systems with different irrigation. We compared; multi-point irrigation into a pond (DeepFlow); one-point irrigation resulting in a thin film of running water (NutrientFlow) and multi-point irrigation as droplets through air (Aeroponic). Second objective was to compare press pots as propagation medium with nutrient solution as propagation medium. The comparison included DeepFlow water-rooted cuttings with either the stem 1 cm into the nutrient solution or with the stem 1 cm above the nutrient solution. Measurements included fresh weight, dry weight, length, water supply, nutrient supply, and oxygen levels. To account for differences in radiation sum received, crop performance was evaluated with Radiation Use Efficiency (RUE) expressed as dry weight over sum of Photosynthetically Active Radiation. The reference, DeepFlow with substrate-based propagation, showed the highest RUE, even while the oxygen supply provided by irrigation was potentially growth limiting. DeepFlow with water-based propagation showed 15-17% lower RUEs than the reference. NutrientFlow showed 8% lower RUE than the reference, in combination with potentially limiting irrigation supply of nutrients and oxygen. Aeroponic showed RUE levels similar to the reference and Aeroponic had non-limiting irrigation supply of water, nutrients, and oxygen. Water-based propagation affected the subsequent

  7. The influence of ascorbic acid on the oxygen consumption and the heat production by the cells of wheat seedling roots with their mitochondrial electron transport chain inhibited at complexes I and III

    International Nuclear Information System (INIS)

    Gordon, L.K.; Rakhmatullina, D.F.; Ogorodnikova, T.I.; Alyabyev, A.J.; Minibayeva, F.V.; Loseva, N.L.; Mityashina, S.Y.

    2007-01-01

    The influence of exogenous ascorbic acid (AsA) on oxidative phosphorylation was studied using wheat seedling roots. Treatment of them with AsA stimulated the rates of oxygen consumption and the heat production and caused a decrease of the respiratory coefficient. The increase in respiration was prevented by inhibitors of ascorbate oxidase, diethyldithiocarbamate (DEDTC), and of cytochrome oxidase, cyanide (KCN). Exogenous AsA sharply stimulated the rate of oxygen consumption of roots when complexes I and III of the mitochondrial electron transport chain were inhibited by rotenone and antimycin A, respectively, while the rates of heat production did not change significantly. It is concluded that AsA is a potent energy substrate, which can be used in conditions of failing I and III complexes in the mitochondrial electron transport chain

  8. Simultaneous evaluation of substrate-dependent oxygen consumption rates and mitochondrial membrane potential by TMRM and safranin in cortical mitochondria.

    Science.gov (United States)

    Chowdhury, Subir Roy; Djordjevic, Jelena; Albensi, Benedict C; Fernyhough, Paul

    2015-12-08

    Mitochondrial membrane potential (mtMP) is critical for maintaining the physiological function of the respiratory chain to generate ATP. The present study characterized the inter-relationship between mtMP, using safranin and tetramethyl rhodamine methyl ester (TMRM), and mitochondrial respiratory activity and established a protocol for functional analysis of mitochondrial bioenergetics in a multi-sensor system. Coupled respiration was decreased by 27 and 30-35% in the presence of TMRM and safranin respectively. Maximal respiration was higher than coupled with Complex I- and II-linked substrates in the presence of both dyes. Safranin showed decreased maximal respiration at a higher concentration of carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP) compared with TMRM. FCCP titration revealed that maximal respiration in the presence of glutamate and malate was not sustainable at higher FCCP concentrations as compared with pyruvate and malate. Oxygen consumption rate (OCR) and mtMP in response to mitochondrial substrates were higher in isolated mitochondria compared with tissue homogenates. Safranin exhibited higher sensitivity to changes in mtMP than TMRM. This multi-sensor system measured mitochondrial parameters in the brain of transgenic mice that model Alzheimer's disease (AD), because mitochondrial dysfunction is believed to be a primary event in the pathogenesis of AD. The coupled and maximal respiration of electron transport chain were decreased in the cortex of AD mice along with the mtMP compared with age-matched controls. Overall, these data demonstrate that safranin and TMRM are suitable for the simultaneous evaluation of mtMP and respiratory chain activity using isolated mitochondria and tissue homogenate. However, certain care should be taken concerning the selection of appropriate substrates and dyes for specific experimental circumstances. © 2016 Authors.

  9. Energy productivity, fertilization rate and profitability of wheat production after various predecessors II.Profitability of wheat production

    Directory of Open Access Journals (Sweden)

    Z. Uhr

    2016-03-01

    Full Text Available Abstract. In the course of our study on the adaptation of modern genotypes common winter wheat (Triticum aestivum to the requirements of sustainable agriculture data were received concerning the influence of the predecessor and nitrogen fertilizer rate on energy efficiency and recyclable nitrogen fertilization and profitability of productivity.We share these data with the scientific community, as they are up-to-date and informative in both theoretical and practical aspects. The analyses are based on data from field experiments fertilizer derived after predecessor cereals – regular crop of sorghum, millet, maize and legumes after predecessor - separate sowing of chickpeas. Energy efficiency of nitrogen fertilization was calculated as the ratio between the energy supplied in the additional grain yield and energy input in the form of fertilizers. Refundable efficiency of nitrogen fertilization is the additional amount of nitrogen accumulated in the grain, with respect to the applied nitrogen fertilization. Economic profitability of production is evaluated by coefficient R = P/Ra (ratio of benefits/costs. The results show that energy efficiency and recyclable nitrogen fertilization are on average five times higher after cereal than after legumes predecessor, and decreased with increasing the fertilizer rate, the decrease was statistically significant only for the first item (exponent. Profitability ratio of production after the introduction of legumes predecessor in crop rotation increases by an average of 42% and retains maximum values of fertilization levels 0.06, 0.12 and 0.18 t/ha nitrogen. Profitability of wheat production using pre-legumes crop is not determined by the parameters nitrogen fertilizer rate and energy efficiency of nitrogen fertilization and refundable efficiency of nitrogen fertilization.

  10. Singlet oxygen production by combining erythrosine and halogen light for photodynamic inactivation of Streptococcus mutans.

    Science.gov (United States)

    Fracalossi, Camila; Nagata, Juliana Yuri; Pellosi, Diogo Silva; Terada, Raquel Sano Suga; Hioka, Noboru; Baesso, Mauro Luciano; Sato, Francielle; Rosalen, Pedro Luiz; Caetano, Wilker; Fujimaki, Mitsue

    2016-09-01

    Photodynamic inactivation of microorganisms is based on a photosensitizing substance which, in the presence of light and molecular oxygen, produces singlet oxygen, a toxic agent to microorganisms and tumor cells. This study aimed to evaluate singlet oxygen quantum yield of erythrosine solutions illuminated with a halogen light source in comparison to a LED array (control), and the photodynamic effect of erythrosine dye in association with the halogen light source on Streptococcus mutans. Singlet oxygen quantum yield of erythrosine solutions was quantified using uric acid as a chemical-probe in an aqueous solution. The in vitro effect of the photodynamic antimicrobial activity of erythrosine in association with the halogen photopolimerizing light on Streptococcus mutans (UA 159) was assessed during one minute. Bacterial cultures treated with erythrosine alone served as negative control. Singlet oxygen with 24% and 2.8% degradation of uric acid in one minute and a quantum yield of 0.59 and 0.63 was obtained for the erythrosine samples illuminated with the halogen light and the LED array, respectively. The bacterial cultures with erythrosine illuminated with the halogen light presented a decreased number of CFU mL(-1) in comparison with the negative control, with minimal inhibitory concentrations between 0.312 and 0.156mgmL(-1). The photodynamic response of erythrosine induced by the halogen light was capable of killing S. mutans. Clinical trials should be conducted to better ascertain the use of erythrosine in association with halogen light source for the treatment of dental caries. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Wii, Kinect, and Move. Heart Rate, Oxygen Consumption, Energy Expenditure, and Ventilation due to Different Physically Active Video Game Systems in College Students

    OpenAIRE

    SCHEER, KRISTA S.; SIEBRANT, SARAH M.; BROWN, GREGORY A.; SHAW, BRANDON S.; SHAW, INA

    2014-01-01

    Nintendo Wii, Sony Playstation Move, and Microsoft XBOX Kinect are home video gaming systems that involve player movement to control on-screen game play. Numerous investigations have demonstrated that playing Wii is moderate physical activity at best, but Move and Kinect have not been as thoroughly investigated. The purpose of this study was to compare heart rate, oxygen consumption, and ventilation while playing the games Wii Boxing, Kinect Boxing, and Move Gladiatorial Combat. Heart rate, o...

  12. Maximum production rate optimization for sulphuric acid decomposition process in tubular plug-flow reactor

    International Nuclear Information System (INIS)

    Wang, Chao; Chen, Lingen; Xia, Shaojun; Sun, Fengrui

    2016-01-01

    A sulphuric acid decomposition process in a tubular plug-flow reactor with fixed inlet flow rate and completely controllable exterior wall temperature profile and reactants pressure profile is studied in this paper by using finite-time thermodynamics. The maximum production rate of the aimed product SO 2 and the optimal exterior wall temperature profile and reactants pressure profile are obtained by using nonlinear programming method. Then the optimal reactor with the maximum production rate is compared with the reference reactor with linear exterior wall temperature profile and the optimal reactor with minimum entropy generation rate. The result shows that the production rate of SO 2 of optimal reactor with the maximum production rate has an increase of more than 7%. The optimization of temperature profile has little influence on the production rate while the optimization of reactants pressure profile can significantly increase the production rate. The results obtained may provide some guidelines for the design of real tubular reactors. - Highlights: • Sulphuric acid decomposition process in tubular plug-flow reactor is studied. • Fixed inlet flow rate and controllable temperature and pressure profiles are set. • Maximum production rate of aimed product SO 2 is obtained. • Corresponding optimal temperature and pressure profiles are derived. • Production rate of SO 2 of optimal reactor increases by 7%.

  13. The effect of lipid peroxidation products on reactive oxygen species formation and nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 macrophages

    Czech Academy of Sciences Publication Activity Database

    Ambrožová, Gabriela; Pekarová, Michaela; Lojek, Antonín

    2011-01-01

    Roč. 25, č. 1 (2011), s. 145-152 ISSN 0887-2333 R&D Projects: GA MŠk(CZ) OC08058; GA ČR(CZ) GA524/08/1753 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : lipid peroxidation products * reactive oxygen species * nitric oxide Subject RIV: BO - Biophysics Impact factor: 2.775, year: 2011

  14. Tapping Into Rate Flexibility: Musical Training Facilitates Synchronization Around Spontaneous Production Rates

    Directory of Open Access Journals (Sweden)

    Rebecca Scheurich

    2018-04-01

    Full Text Available The ability to flexibly adapt one’s behavior is critical for social tasks such as speech and music performance, in which individuals must coordinate the timing of their actions with others. Natural movement frequencies, also called spontaneous rates, constrain synchronization accuracy between partners during duet music performance, whereas musical training enhances synchronization accuracy. We investigated the combined influences of these factors on the flexibility with which individuals can synchronize their actions with sequences at different rates. First, we developed a novel musical task capable of measuring spontaneous rates in both musicians and non-musicians in which participants tapped the rhythm of a familiar melody while hearing the corresponding melody tones. The novel task was validated by similar measures of spontaneous rates generated by piano performance and by the tapping task from the same pianists. We then implemented the novel task with musicians and non-musicians as they synchronized tapping of a familiar melody with a metronome at their spontaneous rates, and at rates proportionally slower and faster than their spontaneous rates. Musicians synchronized more flexibly across rates than non-musicians, indicated by greater synchronization accuracy. Additionally, musicians showed greater engagement of error correction mechanisms than non-musicians. Finally, differences in flexibility were characterized by more recurrent (repetitive and patterned synchronization in non-musicians, indicative of greater temporal rigidity.

  15. Tapping Into Rate Flexibility: Musical Training Facilitates Synchronization Around Spontaneous Production Rates

    Science.gov (United States)

    Scheurich, Rebecca; Zamm, Anna; Palmer, Caroline

    2018-01-01

    The ability to flexibly adapt one’s behavior is critical for social tasks such as speech and music performance, in which individuals must coordinate the timing of their actions with others. Natural movement frequencies, also called spontaneous rates, constrain synchronization accuracy between partners during duet music performance, whereas musical training enhances synchronization accuracy. We investigated the combined influences of these factors on the flexibility with which individuals can synchronize their actions with sequences at different rates. First, we developed a novel musical task capable of measuring spontaneous rates in both musicians and non-musicians in which participants tapped the rhythm of a familiar melody while hearing the corresponding melody tones. The novel task was validated by similar measures of spontaneous rates generated by piano performance and by the tapping task from the same pianists. We then implemented the novel task with musicians and non-musicians as they synchronized tapping of a familiar melody with a metronome at their spontaneous rates, and at rates proportionally slower and faster than their spontaneous rates. Musicians synchronized more flexibly across rates than non-musicians, indicated by greater synchronization accuracy. Additionally, musicians showed greater engagement of error correction mechanisms than non-musicians. Finally, differences in flexibility were characterized by more recurrent (repetitive) and patterned synchronization in non-musicians, indicative of greater temporal rigidity. PMID:29681872

  16. Wii, Kinect, and Move. Heart Rate, Oxygen Consumption, Energy Expenditure, and Ventilation due to Different Physically Active Video Game Systems in College Students.

    Science.gov (United States)

    Scheer, Krista S; Siebrant, Sarah M; Brown, Gregory A; Shaw, Brandon S; Shaw, Ina

    Nintendo Wii, Sony Playstation Move , and Microsoft XBOX Kinect are home video gaming systems that involve player movement to control on-screen game play. Numerous investigations have demonstrated that playing Wii is moderate physical activity at best, but Move and Kinect have not been as thoroughly investigated. The purpose of this study was to compare heart rate, oxygen consumption, and ventilation while playing the games Wii Boxing, Kinect Boxing, and Move Gladiatorial Combat. Heart rate, oxygen consumption, and ventilation were measured at rest and during a graded exercise test in 10 males and 9 females (19.8 ± 0.33 y, 175.4 ± 2.0 cm, 80.2 ± 7.7 kg,). On another day, in a randomized order, the participants played Wii Boxing, K inect Boxing, and Move Gladiatorial Combat while heart rate, ventilation, and oxygen consumption were measured. There were no differences in heart rate (116.0 ± 18.3 vs. 119.3 ± 17.6 vs. 120.1 ± 17.6 beats/min), oxygen consumption (9.2 ± 3.0 vs. 10.6 ± 2.4 vs. 9.6 ± 2.4 ml/kg/min), or minute ventilation (18.9 ± 5.7 vs. 20.8 ± 8.0 vs. 19.7 ± 6.4 L/min) when playing Wii boxing, Kinect boxing, or Move Gladiatorial Combat (respectively). Playing Nintendo Wii Boxing, XBOX Kinect Boxing, and Sony PlayStation Move Gladiatorial Combat all increase heart rate, oxygen consumption, and ventilation above resting levels but there were no significant differences between gaming systems. Overall, playing a "physically active" home video game system does not meet the minimal threshold for moderate intensity physical activity, regardless of gaming system.

  17. r-PROCESS LANTHANIDE PRODUCTION AND HEATING RATES IN KILONOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Lippuner, Jonas; Roberts, Luke F., E-mail: jlippuner@tapir.caltech.edu [TAPIR, Walter Burke Institute for Theoretical Physics, California Institute of Technology, MC 350-17, 1200 E California Boulevard, Pasadena CA 91125 (United States)

    2015-12-20

    r-process nucleosynthesis in material ejected during neutron star mergers may lead to radioactively powered transients called kilonovae. The timescale and peak luminosity of these transients depend on the composition of the ejecta, which determines the local heating rate from nuclear decays and the opacity. Kasen et al. and Tanaka and Hotokezaka pointed out that lanthanides can drastically increase the opacity in these outflows. We use the new general-purpose nuclear reaction network SkyNet to carry out a parameter study of r-process nucleosynthesis for a range of initial electron fractions Y{sub e}, initial specific entropies s, and expansion timescales τ. We find that the ejecta is lanthanide-free for Y{sub e} ≳ 0.22−0.30, depending on s and τ. The heating rate is insensitive to s and τ, but certain, larger values of Y{sub e} lead to reduced heating rates, due to individual nuclides dominating the heating. We calculate approximate light curves with a simplified gray radiative transport scheme. The light curves peak at about a day (week) in the lanthanide-free (-rich) cases. The heating rate does not change much as the ejecta becomes lanthanide-free with increasing Y{sub e}, but the light-curve peak becomes about an order of magnitude brighter because it peaks much earlier when the heating rate is larger. We also provide parametric fits for the heating rates between 0.1 and 100 days, and we provide a simple fit in Y{sub e}, s, and τ to estimate whether or not the ejecta is lanthanide-rich.

  18. r-PROCESS LANTHANIDE PRODUCTION AND HEATING RATES IN KILONOVAE

    International Nuclear Information System (INIS)

    Lippuner, Jonas; Roberts, Luke F.

    2015-01-01

    r-process nucleosynthesis in material ejected during neutron star mergers may lead to radioactively powered transients called kilonovae. The timescale and peak luminosity of these transients depend on the composition of the ejecta, which determines the local heating rate from nuclear decays and the opacity. Kasen et al. and Tanaka and Hotokezaka pointed out that lanthanides can drastically increase the opacity in these outflows. We use the new general-purpose nuclear reaction network SkyNet to carry out a parameter study of r-process nucleosynthesis for a range of initial electron fractions Y e , initial specific entropies s, and expansion timescales τ. We find that the ejecta is lanthanide-free for Y e ≳ 0.22−0.30, depending on s and τ. The heating rate is insensitive to s and τ, but certain, larger values of Y e lead to reduced heating rates, due to individual nuclides dominating the heating. We calculate approximate light curves with a simplified gray radiative transport scheme. The light curves peak at about a day (week) in the lanthanide-free (-rich) cases. The heating rate does not change much as the ejecta becomes lanthanide-free with increasing Y e , but the light-curve peak becomes about an order of magnitude brighter because it peaks much earlier when the heating rate is larger. We also provide parametric fits for the heating rates between 0.1 and 100 days, and we provide a simple fit in Y e , s, and τ to estimate whether or not the ejecta is lanthanide-rich

  19. Traditional product rating in gastronomic circuits: lessons from the Cerrado

    Directory of Open Access Journals (Sweden)

    Moises Villamil Balestro

    2015-04-01

    Full Text Available The social construction of differentiated and nested markets and alternative agrifood systems in relation to conventional agribusiness systems of modern agriculture constitute a significant strategy to overcome the exclusion of millions of small farmers and peasants. On its turn, the growing demand and differentiated use of traditional products in the gastronomic circuit, as well as new forms of interaction between chefs and farmers who produce traditional products, can be a drive for the construction of these differentiated markets. One of the findings of this article is that the asymmetry between chefs and producers in the possession of symbolic capital necessary for the assessment process of the typical products has a negative impact for the distribution of economic capital and, as a result, there is great unevenness between the prices paid to produces and the prices of the dishes incorporating such products as delicacies. The appropriation of the economic result of the valuation decreases as a result of this process. The producer knowledge is often appropriated and reproduced in the assessment process and he does not take advantage of it. Departing from contributions of economic sociology and the economy of singularities, such issues are discussed by this article.

  20. Selective production of oxygenates from CO2 hydrogenation over mesoporous silica supported Cu-Ga nanocomposite catalyst

    KAUST Repository

    Huang, Kuo-Wei

    2017-11-23

    Carbon dioxide hydrogenation to oxygenates (methanol and dimethyl ether (DME)) was investigated over bifunctional supported copper catalysts promoted with gallium (Ga). Supported Cu-Ga nanocomposite catalysts were characterized by X-ray diffraction, transmission electron microscopy with energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and H2 temperature programmed reduction. In comparison with Cu-SBA-15 based catalysts, Ga promoted catalysts prepared by the urea deposition method (CuGa/SBA-15-UDP) was found active and selective for CO2 hydrogenation to oxygenates. The use of Ga as the promoter showed increased acidic sites as confirmed by the NH3-TPD, Pyridine-IR and 2,6-lutidine-IR studies. The favorable effect of Ga on CO2 conversion and selectivity to oxygenate may come from the strong interaction of Ga with silica, which is responsible for the enhanced metal surface area, formation of nanocomposite and metal dispersion. Notably, incorporation of Ga to Cu/SiO2 showed a several-fold higher rate for methanol formation (13.12 mol/gCu·sec) with a reasonable rate for the DME formation (2.15 mol/gCu·sec) as compared to those of Cu/SiO2 catalysts.

  1. Integrated rate expression for the production of glucose equivalent ...

    Indian Academy of Sciences (India)

    WINTEC

    green plants is discussed. The C4 plants are chosen and in these plants, the rate of photosynthesis does not .... overall CO2 assimilation process and glucose pro-. Figure 1. ..... Thus these plants show an optimal growth of an enzyme activity ...

  2. Price promotions and products with low consumer ratings

    OpenAIRE

    Kuo, H. C.; Kuo, H. C.; Nakhata, C.; Nakhata, C.

    2016-01-01

    Previous research indicates the aversive effect of low consumer ratings on consumers’ purchasing decisions. This paper aims to apply decision justifiability theory to investigate how price promotions – price discount and price bundling – can reduce this effect. 517-527.

  3. Production of a recombinant phospholipase A2 in Escherichia coli using resonant acoustic mixing that improves oxygen transfer in shake flasks.

    Science.gov (United States)

    Valdez-Cruz, Norma A; Reynoso-Cereceda, Greta I; Pérez-Rodriguez, Saumel; Restrepo-Pineda, Sara; González-Santana, Jesus; Olvera, Alejandro; Zavala, Guadalupe; Alagón, Alejandro; Trujillo-Roldán, Mauricio A

    2017-07-25

    Shake flasks are widely used during the development of bioprocesses for recombinant proteins. Cultures of recombinant Escherichia coli with orbital mixing (OM) have an oxygen limitation negatively affecting biomass growth and recombinant-protein production. With the aim to improve mixing and aeration in shake flask cultures, we analyzed cultures subjected to OM and the novel resonant acoustic mixing (RAM) by applying acoustic energy to E. coli BL21-Gold (DE3): a producer of recombinant phospholipase A2 (rPLA2) from Micrurus laticollaris snake venom. Comparing OM with RAM (200 rpm vs. 7.5g) at the same initial volumetric oxygen transfer coefficient (k L a ≈ 80 h -1 ) ~69% less biomass was obtained with OM compared with RAM. We analyzed two more conditions increasing agitation until maximal speed (12.5 and 20g), and ~1.6- and ~1.4-fold greater biomass was obtained as compared with cultures at 7.5g. Moreover, the specific growth rate was statistically similar in all cultures carried out in RAM, but ~1.5-fold higher than that in cultures carried out under OM. Almost half of the glucose was consumed in OM, whereas between 80 and 100% of the glucose was consumed in RAM cultures, doubling biomass per glucose yields. Differential organic acid production was observed, but acetate production was prevented at the maximal RAM (20g). The amount of rPLA2 in both, OM and RAM cultures, represented 38 ± 5% of the insoluble protein. A smaller proportion of α-helices and β-sheet of purified inclusion bodies (IBs) were appreciated by ATR-FTIR from cultures carried out under OM, than those from RAM. At maximal agitation by RAM, internal E. coli localization patterns of protein aggregation changed, as well as, IBs proteolytic degradation, in conjunction with the formation of small external vesicles, although these changes did not significantly affect the cell survival response. In moderate-cell-density recombinant E. coli BL21-Gold (DE3) cultures, the agitation increases in

  4. 78 FR 1277 - International Product Change-Global Expedited Package Services-Non-Published Rates

    Science.gov (United States)

    2013-01-08

    ... POSTAL SERVICE International Product Change--Global Expedited Package Services-- Non-Published...-- Non-Published Rates 4 (GEPS-NPR 4) to the Competitive Products List. DATES: Effective date: January 8... add Global Expedited Package Services-- Non-Published Rates 4 (GEPS-NPR 4) to the Competitive Products...

  5. Estimation of Sand Production Rate Using Geomechanical and Hydromechanical Models

    Directory of Open Access Journals (Sweden)

    Son Tung Pham

    2017-01-01

    Full Text Available This paper aims to develop a numerical model that can be used in sand control during production phase of an oil and gas well. The model is able to predict not only the onset of sand production using critical bottom hole pressure inferred from geomechanical modelling, but also the mass of sand produced versus time as well as the change of porosity versus space and time using hydromechanical modelling. A detailed workflow of the modelling was presented with each step of calculations. The empirical parameters were calibrated using laboratory data. Then the modelling was applied in a case study of an oilfield in Cuu Long basin. In addition, a sensitivity study of the effect of drawdown pressure was presented in this paper. Moreover, a comparison between results of different hydromechanical models was also addressed. The outcome of this paper demonstrated the possibility of modelling the sand production mass in real cases, opening a new approach in sand control in petroleum industry.

  6. Renewable Bio-Solar Hydrogen Production From Robust Oxygenic Phototrophs: The Second Generation

    Science.gov (United States)

    2014-07-14

    adds a layer of complexity due to oxygen’s natural prevalence in air. Furthermore, oxygenic photosynthesis, the most effective photosynthesis, is...between the oxic and anoxic layers as well as the anaerobic water and benthic layers . (c) We have tested the hypothesis that sequence variations...both hydrogenase and urease in Helicobacter pylori, Mol Microbiol, 39 (2001) 176-182. [199] L. Forzi, R.G. Sawers, Maturation of [NiFe]-hydrogenases

  7. Surface-Selective Preferential Production of Reactive Oxygen Species on Piezoelectric Ceramics for Bacterial Killing

    OpenAIRE

    Tan, Guoxin; Wang, Shuangying; Zhu, Ye; Zhou, Lei; Yu, Peng; Wang, Xiaolan; He, Tianrui; Chen, Junqi; Mao, Chuanbin; Ning, Chengyun

    2016-01-01

    Reactive oxygen species (ROS) can be used to kill bacterial cells, and thus the selective generation of ROS from material surfaces is an emerging direction in antibacterial material discovery. We found the polarization of piezoelectric ceramic causes the two sides of the disk to become positively and negatively charged, which translate into cathode and anode surfaces in an aqueous solution. Because of the microelectrolysis of water, ROS are preferentially formed on the cathode surface. Conseq...

  8. Hot oxygen atoms: Their generation and chemistry. [Production by sputtering; reaction with butenes

    Energy Technology Data Exchange (ETDEWEB)

    Ferrieri, R.A.; Chu, Yung Y.; Wolf, A.P.

    1987-01-01

    Oxygen atoms with energies between 1 and 10 eV have been produced through ion beam sputtering from metal oxide targets. Argon ion beams were used on Ta/sub 2/O/sub 5/ and V/sub 2/O/sub 5/. Results show that some control may be exerted over the atom's kinetic energy by changing the target. Reactions of the hot O(/sup 3/P) with cis- and trans-butenes were investigated. (DLC)

  9. Effects of oxygen content and heating rate on phase transition behavior in Bi2(V0.95Ti0.05)O5.475-x

    International Nuclear Information System (INIS)

    Taninouchi, Yu-ki; Uda, Tetsuya; Ichitsubo, Tetsu; Awakura, Yasuhiro; Matsubara, Eiichiro

    2011-01-01

    Highlights: → Phase transition behavior of oxide-ion conductor Bi 2 (V 0.95 Ti 0.05 )O 5.475-x , which has various thermal histories and physical forms. → At the same heating rate of 10 K min -1 , Bi 2 (V 0.95 Ti 0.05 )O 5.475-x with less oxygen content exhibits transition from α f to β f at a higher temperature and the transition from β f to γ f at a lower temperature. → α f directly transformed to β f at fast heating rates. At a slower heating rate of 2 K min -1 , β f precipitated from α f due to the sufficient diffusion of Ti and oxygen vacancies. - Abstract: The phase transition behavior of oxide-ion conductor Bi 2 (V 0.95 Ti 0.05 )O 5.475-x , which has various thermal histories and sample forms, has been studied by means of differential scanning calorimetry. Thermogravimetric analysis revealed that the oxygen content per compositional formula varied with the applied thermal treatment, although no significant structural difference was observed by X-ray diffraction (XRD) analysis. The phase transition behavior from α f to β f and from β f to γ f , observed at a heating rate of 10 K min -1 , are markedly affected by the sample preparation. For example, the endothermic peak of the transition from α f to β f appeared at around 400 deg. C for quenched powder and at around 320 deg. C for powder cooled at 0.5 K min -1 . The trend of the transition temperatures can be qualitatively explained in terms of oxygen content, i.e., Bi 2 (V 0.95 Ti 0.05 )O 5.475-x with less oxygen content exhibits the transition from α f to β f at a higher temperature and the transition from β f to γ f at a lower temperature. We confirmed the two types of transition behavior from α f to β f depending on heating rate of DSC and high-temperature X-ray diffraction (HT-XRD) analysis. At rapid heating rates of 10 and 40 K min -1 , α f transformed to β f directly. Meanwhile, at a slow heating rate of 2 K min -1 , the β f precipitated from α f because slow heating

  10. Continuous biohydrogen production using cheese whey: Improving the hydrogen production rate

    Energy Technology Data Exchange (ETDEWEB)

    Davila-Vazquez, Gustavo; Cota-Navarro, Ciria Berenice; Razo-Flores, Elias [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San Jose 2055, Lomas 4a seccion, C.P. 78216, San Luis Potosi, S.L.P (Mexico); Rosales-Colunga, Luis Manuel; de Leon-Rodriguez, Antonio [Division de Biologia Molecular, Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San Jose 2055, Lomas 4a seccion, C.P. 78216, San Luis Potosi, S.L.P (Mexico)

    2009-05-15

    Due to the renewed interest in finding sustainable fuels or energy carriers, biohydrogen (Bio-H{sub 2}) from biomass is a promising alternative. Fermentative Bio-H{sub 2} production was studied in a continuous stirred tank reactor (CSTR) operated during 65.6 d with cheese whey (CW) as substrate. Three hydraulic retention times (HRTs) were tested (10, 6 and 4 h) and the highest volumetric hydrogen production rate (VHPR) was attained with HRT of 6 h. Therefore, four organic loading rates (OLRs) at a fixed HRT of 6 h were tested thereafter, being: 92.4, 115.5, 138.6 and 184.4 g lactose/L/d. The highest VHPR (46.61 mmol H{sub 2}/L/h) and hydrogen molar yield (HMY) of 2.8 mol H{sub 2}/mol lactose were found at an OLR of 138.6 g lactose/L/d; a sharp fall in VHPR occurred at an OLR of 184.4 g lactose/L/d. Butyric, propionic and acetic acids were the main soluble metabolites found, with butyric-to-acetic ratios ranging from 1.0 to 2.4. Bacterial community was identified by partial sequence analysis of the 16S rRNA and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that at HRT of 10 h and 6 h were dominated by the Clostridium genus. The VHPR attained in this study is the highest reported value for a CSTR system using CW as substrate with anaerobic sludge as inoculum and represents a 33-fold increase compared to a previous study. Thus, it was demonstrated that continuous fermentative Bio-H{sub 2} production from CW can be significantly enhanced by an appropriate selection of parameters such as HRT and OLR. Enhancements in VHPR are significant because it is a critical parameter to determine the full-scale practical application of fermentation technologies that will be used for sustainable and clean energy generation. (author)

  11. Effects of Agitation, Aeration and Temperature on Production of a Novel Glycoprotein GP-1 by Streptomyces kanasenisi ZX01 and Scale-Up Based on Volumetric Oxygen Transfer Coefficient

    Directory of Open Access Journals (Sweden)

    Yong Zhou

    2018-01-01

    Full Text Available The effects of temperature, agitation and aeration on glycoprotein GP-1 production by Streptomyces kanasenisi ZX01 in bench-scale fermentors were systematically investigated. The maximum final GP-1 production was achieved at an agitation speed of 200 rpm, aeration rate of 2.0 vvm and temperature of 30 °C. By using a dynamic gassing out method, the effects of agitation and aeration on volumetric oxygen transfer coefficient (kLa were also studied. The values of volumetric oxygen transfer coefficient in the logarithmic phase increased with increase of agitation speed (from 14.53 to 32.82 h−1 and aeration rate (from 13.21 to 22.43 h−1. In addition, a successful scale-up from bench-scale to pilot-scale was performed based on volumetric oxygen transfer coefficient, resulting in final GP-1 production of 3.92, 4.03, 3.82 and 4.20 mg/L in 5 L, 15 L, 70 L and 500 L fermentors, respectively. These results indicated that constant volumetric oxygen transfer coefficient was appropriate for the scale-up of batch fermentation of glycoprotein GP-1 by Streptomyces kanasenisi ZX01, and this scale-up strategy successfully achieved 100-fold scale-up from bench-scale to pilot-scale fermentor.

  12. The Modeling of Logistics and Coordination of the Rate of Commodities Production with the Rate of their Disposal

    Directory of Open Access Journals (Sweden)

    Sherstennykov Yuriy V.

    2016-08-01

    Full Text Available The economic objective of the modern high-tech enterprise is the optimal expansion of its own market niche and bringing the production capacities in accordance with the current demand for the products. An important role in this respect is played by issues of optimal organization of the enterprise logistics, marketing analysis of the current demand and effective advertising campaign aimed at maximal use of the available production capacity and creation of proper conditions for developing, in particular for increasing the production capacities. The purpose of the article is the elaboration of economic and mathematical models of enterprise production activity taking into account the logistics and market demand; the use of the elaborated model to harmonize the rate of production of everyday commodities with the rate of their disposal. Two variants of the enterprise logistics schemes are analyzed. The influence of the advertising company on expanding the enterprise market niche is studied. A model that allows conducting a detailed study of the influence of market conditions on the pace of sales has been developed. It is appropriate to apply the model for the integrated coordination of the production rate of commodities of everyday demand with the dynamics of flows of commodities and services disposal.

  13. Methyl chavicol: characterization of its biogenic emission rate, abundance, and oxidation products in the atmosphere

    Directory of Open Access Journals (Sweden)

    N. C. Bouvier-Brown

    2009-03-01

    Full Text Available We report measurements of ambient atmospheric mixing ratios for methyl chavicol and determine its biogenic emission rate. Methyl chavicol, a biogenic oxygenated aromatic compound, is abundant within and above Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. Methyl chavicol was detected simultaneously by three in-situ instruments – a gas chromatograph with mass spectrometer detector (GC-MS, a proton transfer reaction mass spectrometer (PTR-MS, and a thermal desorption aerosol GC-MS (TAG – and found to be abundant within and above Blodgett Forest. Methyl chavicol atmospheric mixing ratios are strongly correlated with 2-methyl-3-buten-2-ol (MBO, a light- and temperature-dependent biogenic emission from the ponderosa pine trees at Blodgett Forest. Scaling from this correlation, methyl chavicol emissions account for 4–68% of the carbon mass emitted as MBO in the daytime, depending on the season. From this relationship, we estimate a daytime basal emission rate of 0.72–10.2 μgCg−1 h−1, depending on needle age and seasonality. We also present the first observations of its oxidation products (4-methoxybenzaldehyde and 4-methyoxy benzene acetaldehyde in the ambient atmosphere. Methyl chavicol is a major essential oil component of many plant species. This work suggests that methyl chavicol plays a significant role in the atmospheric chemistry of Blodgett Forest, and potentially other sites, and should be included explicitly in both biogenic volatile organic carbon emission and atmospheric chemistry models.

  14. Comparative techno-economic analysis and process design for indirect liquefaction pathways to distillate-range fuels via biomass-derived oxygenated intermediates upgrading: Liquid Transportation Fuel Production via Biomass-derived Oxygenated Intermediates Upgrading

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Eric C. D. [National Renewable Energy Laboratory, Golden CO USA; Snowden-Swan, Lesley J. [Pacific Northwest National Laboratory, Richland WA USA; Talmadge, Michael [National Renewable Energy Laboratory, Golden CO USA; Dutta, Abhijit [National Renewable Energy Laboratory, Golden CO USA; Jones, Susanne [Pacific Northwest National Laboratory, Richland WA USA; Ramasamy, Karthikeyan K. [Pacific Northwest National Laboratory, Richland WA USA; Gray, Michel [Pacific Northwest National Laboratory, Richland WA USA; Dagle, Robert [Pacific Northwest National Laboratory, Richland WA USA; Padmaperuma, Asanga [Pacific Northwest National Laboratory, Richland WA USA; Gerber, Mark [Pacific Northwest National Laboratory, Richland WA USA; Sahir, Asad H. [National Renewable Energy Laboratory, Golden CO USA; Tao, Ling [National Renewable Energy Laboratory, Golden CO USA; Zhang, Yanan [National Renewable Energy Laboratory, Golden CO USA

    2016-09-27

    This paper presents a comparative techno-economic analysis (TEA) of five conversion pathways from biomass to gasoline-, jet-, and diesel-range hydrocarbons via indirect liquefaction with specific focus on pathways utilizing oxygenated intermediates. The four emerging pathways of interest are compared with one conventional pathway (Fischer-Tropsch) for the production of the hydrocarbon blendstocks. The processing steps of the four emerging pathways include: biomass to syngas via indirect gasification, gas cleanup, conversion of syngas to alcohols/oxygenates followed by conversion of alcohols/oxygenates to hydrocarbon blendstocks via dehydration, oligomerization, and hydrogenation. Conversion of biomass-derived syngas to oxygenated intermediates occurs via three different pathways, producing: 1) mixed alcohols over a MoS2 catalyst, 2) mixed oxygenates (a mixture of C2+ oxygenated compounds, predominantly ethanol, acetic acid, acetaldehyde, ethyl acetate) using an Rh-based catalyst, and 3) ethanol from syngas fermentation. This is followed by the conversion of oxygenates/alcohols to fuel-range olefins in two approaches: 1) mixed alcohols/ethanol to 1-butanol rich mixture via Guerbet reaction, followed by alcohol dehydration, oligomerization, and hydrogenation, and 2) mixed oxygenates/ethanol to isobutene rich mixture and followed by oligomerization and hydrogenation. The design features a processing capacity of 2,000 tonnes/day (2,205 short tons) of dry biomass. The minimum fuel selling prices (MFSPs) for the four developing pathways range from $3.40 to $5.04 per gasoline-gallon equivalent (GGE), in 2011 US dollars. Sensitivity studies show that MFSPs can be improved with co-product credits and are comparable to the commercial Fischer-Tropsch benchmark ($3.58/GGE). Overall, this comparative TEA study documents potential economics for the developmental biofuel pathways via mixed oxygenates.

  15. Effects of dissolved oxygen concentration on photosynthetic bacteria wastewater treatment: Pollutants removal, cell growth and pigments production.

    Science.gov (United States)

    Meng, Fan; Yang, Anqi; Zhang, Guangming; Wang, Hangyao

    2017-10-01

    Dissolved oxygen (DO) is an important parameter in photosynthetic bacteria (PSB) wastewater treatment. This study set different DO levels and detected the pollutants removal, PSB growth and pigments production. Results showed that DO significantly influenced the performances of PSB wastewater treatment process. The highest COD (93%) and NH 3 -N removal (83%) was achieved under DO of 4-8mg/L, but DO of 2-4mg/L was recommended considering the aeration cost. PSB biomass reached 1645mg/L under DO of 4-8mg/L with satisfying co-enzyme Q10 content. The biomass yield was relatively stable at all DO levels. For bacteriochlorophyll and carotenoids, DO>1mg/L could satisfy their production. On the other hand, DOpigments production occurred at 24h; biomass reached peak at 48h; and the optimal time for pollutants removal was 72h. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Modulation of cisplatin-induced reactive oxygen species production by fullerene C(60 in normal and transformed lymphoid cells

    Directory of Open Access Journals (Sweden)

    D. V. Franskevych

    2016-02-01

    Full Text Available The early response of normal (Wistar rat thymocytes and transformed (mice lymphoid leukemia L1210 cells to treatment with anticancer drug cisplatin or to combined treatment with cisplatin and carbon nanostructure fullerene C60 was studied. We demonstra