WorldWideScience

Sample records for measuring oxygen carbon

  1. Range measurements of keV hydrogen ions in solid oxygen and carbon monoxide

    International Nuclear Information System (INIS)

    Schou, J.; Soerensen, H.; Andersen, H.H.; Nielsen, M.; Rune, J.

    1984-01-01

    Ranges of 1.3-3.5 keV/atom hydrogen and deuterium molecular ions have been measured by a thin-film reflection method. The technique, used here for range measurements in solid oxygen and carbon monoxide targets, is identical to the one used previously for range measurements in hydrogen and nitrogen. The main aim was to look for phase-effects, i.e. gas-solid differences in the stopping processes. While measured ranges in solid oxygen were in agreement with known gas data, the ranges in solid carbon monoxide were up to 50% larger than those calculated from gas-stopping data. The latter result agrees with that previously found for solid nitrogen. (orig.)

  2. Measurement of total-body oxygen, nitrogen, and carbon in vivo by photon activation analysis

    International Nuclear Information System (INIS)

    Ulin, K.

    1984-01-01

    With the aim of assessing nutritional status, the feasibility of measuring the total body quantities of the major body elements, i.e. oxygen, nitrogen, and carbon, using the photon beam of a 45 MV betatron and a whole-body counter, has been evaluated in detail. Following photon activation a single energy γ-radiation (.511 MeV) is observed from all three elements to be measured. The half-lives of 15 O, 13 N, and 11 C, however, are sufficiently different (20.5 min, 10.0 min, and 20.4 min. respectively) to permit their measurement from an analysis of the measured decay curve. Following corrections for interfering reactions, a computer curve-fitting algorithm is used to resolve the data into 15 O, 13 N, and 11 C components. Measurements of O, N, and C have been made both in phantoms and in live and dead rats. A comparison of the body composition results from this technique with results from chemical analysis indicates that measured carbon can quite accurately predict total body fat. The comparison of the total body nitrogen measurement by photon activation with total body protein by chemical analysis was inconclusive and suggests that further work be done to verify the estimated accuracy of the nitrogen measurement

  3. Measurement of characteristic prompt gamma rays emitted from oxygen and carbon in tissue-equivalent samples during proton beam irradiation.

    Science.gov (United States)

    Polf, Jerimy C; Panthi, Rajesh; Mackin, Dennis S; McCleskey, Matt; Saastamoinen, Antti; Roeder, Brian T; Beddar, Sam

    2013-09-07

    The purpose of this work was to characterize how prompt gamma (PG) emission from tissue changes as a function of carbon and oxygen concentration, and to assess the feasibility of determining elemental concentration in tissues irradiated with proton beams. For this study, four tissue-equivalent water-sucrose samples with differing densities and concentrations of carbon, hydrogen, and oxygen were irradiated with a 48 MeV proton pencil beam. The PG spectrum emitted from each sample was measured using a high-purity germanium detector, and the absolute detection efficiency of the detector, average beam current, and delivered dose distribution were also measured. Changes to the total PG emission from (12)C (4.44 MeV) and (16)O (6.13 MeV) per incident proton and per Gray of absorbed dose were characterized as a function of carbon and oxygen concentration in the sample. The intensity of the 4.44 MeV PG emission per incident proton was found to be nearly constant for all samples regardless of their carbon concentration. However, we found that the 6.13 MeV PG emission increased linearly with the total amount (in grams) of oxygen irradiated in the sample. From the measured PG data, we determined that 1.64 × 10(7) oxygen PGs were emitted per gram of oxygen irradiated per Gray of absorbed dose delivered with a 48 MeV proton beam. These results indicate that the 6.13 MeV PG emission from (16)O is proportional to the concentration of oxygen in tissue irradiated with proton beams, showing that it is possible to determine the concentration of oxygen within tissues irradiated with proton beams by measuring (16)O PG emission.

  4. Measurement of the isotopic composition of galactic cosmic ray carbon, nitrogen and oxygen

    International Nuclear Information System (INIS)

    Wiedenbeck, M.E.; Greiner, D.E.; Bieser, F.S.; Crawford, H.J.; Heckman, H.H.; Lindstrom, P.J.

    1979-06-01

    The results of an investigation of the isotopic composition of galactic cosmic ray carbon, nitrogen and oxygen (E approx. 80 to 230 MeV/amu) made using the U.C. Berkeley HKH instrument aboard the ISEE-3 spacecraft are reported. The combination of high mass resolution and a large statistical sample makes possible a precise determination of the relative isotopic abundances for these elements. In local interplanetary space we find: 13 C/C = 0.067 +- 0.008, 15 N/N = 0.54 +- 0.03, 17 O/O 18 O/O = 0.019 +- 0.003

  5. Oxygen and carbon dioxide sensing

    Science.gov (United States)

    Ren, Fan (Inventor); Pearton, Stephen John (Inventor)

    2012-01-01

    A high electron mobility transistor (HEMT) capable of performing as a CO.sub.2 or O.sub.2 sensor is disclosed, hi one implementation, a polymer solar cell can be connected to the HEMT for use in an infrared detection system. In a second implementation, a selective recognition layer can be provided on a gate region of the HEMT. For carbon dioxide sensing, the selective recognition layer can be, in one example, PEI/starch. For oxygen sensing, the selective recognition layer can be, in one example, indium zinc oxide (IZO). In one application, the HEMTs can be used for the detection of carbon dioxide and oxygen in exhaled breath or blood.

  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. Isotopic measurements of carbon and oxygen in carbonates from Bambui Group in the center-north region of Bahia State

    International Nuclear Information System (INIS)

    Torquato, J.R.; Misi, A.

    1978-01-01

    Analyses of 85 carbonate samples of the Bambui Group from the Chapada de Irece, Bahia, exhibit four distinct 13 C and 18 O isotopic ratio groupings. Based on these results the following sedimentation model for the Bambui Group is proposed: 1. A continental environment originating the basal dolomitic limestones and argillacceous dolomites. Isotopic ratios from these rocks fall within ranges considered typical of continental sedimentation: delta 18 C between -2.9 and -6.4%o, and delta 18 O from -5.3 to -10.7%o (PDB). 2. An alternating continental and restricted marine environment resulting in the deposition of laminated dolomitic limestones with thin interbeds of muddy sediments. Delta 13 C ratios of +0.1 to -4.9%o and a mean value of -8.2+-0.3%o delta 18 O are compatible with such an environment. 3. A restricted marine environment dominated by sedimentation of the black, fetid limestones of the upper portion of the sequence. Isotopic ratios for 13 C are all over -1.8%o, up to about +7.5%o, and 18 O ratios vary from-4.9 to -10.0%o. A number of light-grey sileceous dolomites is interbered with the lowermost black limestones of this sequence. Isotopic data for these rocks show a narrow range for delta 18 C values (-0.5 to 1.0%o) and a broader variation for delta 18 O ratios (0.0 to -8.3%o). This latter may be interpreted as indicative of intense evaporation during deposition of the dolomitic facies [pt

  8. Single-experiment simultaneous-measurement of elemental mass-attenuation coefficients of hydrogen, carbon and oxygen for 0.123-1.33 MeV gamma rays

    International Nuclear Information System (INIS)

    Teli, M.T.; Nathuram, R.; Mahajan, C.S.

    2000-01-01

    As it is inconvenient to use elements like hydrogen, carbon and oxygen in pure forms for measurement of their gamma mass-attenuation coefficients, the measurements are to be done indirectly, by using compounds of the elements or a mixture of them. We give here a simple method of measuring the total mass-attenuation coefficients μ/ρ of the elements in a compound simultaneously and in a single experiment through the measurements of the μ/ρ values of the concerned compounds and using the mixture rule. The method is applied for the measurement of μ/ρ of hydrogen, carbon and oxygen by using acetone, ethanol and 1-propanol. Our results (for E γ =0.123-1.33 MeV) are seen to be in better agreement with the theoretical values of Hubbell and Seltzer (1995) [Hubbell J.H. and Seltzer S.M. (1995). Tables of X-ray mass attenuation coefficients and mass energy-absorption coefficients 1 keV to 20 MeV for elements Z=1 to 92 and 48 additional substances of dosimetric interest. NISTIR 5632] as compared to the results of El-Kateb and Abdul-Hamid (1991) [El-Kateb, A.H., Abdul-Hamid, A.S., 1991. Photon attenuation coefficient study of some materials containing hydrogen, carbon, and oxygen. Appl. Rad. Isot. 42, 303-307

  9. A rechargeable carbon-oxygen battery

    DEFF Research Database (Denmark)

    2014-01-01

    The invention relates to a rechargeable battery and a method to operate a rechargeable battery having high efficiency and high energy density for storing energy. The battery stores electrical energy in the bonds of carbon and oxygen atoms by converting carbon dioxide into solid carbon and oxygen....

  10. Precision remote sensor for oxygen and carbon dioxide, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Mesa Photonics proposes development of a passive optical sensor for simultaneous high-precision measurement of oxygen and carbon dioxide profiles within the full...

  11. ON THE CARBON-TO-OXYGEN RATIO MEASUREMENT IN NEARBY SUN-LIKE STARS: IMPLICATIONS FOR PLANET FORMATION AND THE DETERMINATION OF STELLAR ABUNDANCES

    International Nuclear Information System (INIS)

    Fortney, Jonathan J.

    2012-01-01

    Recent high-resolution spectroscopic analysis of nearby FGK stars suggests that a high C/O ratio of greater than 0.8, or even 1.0, is relatively common. Two published catalogs find C/O > 0.8 in 25%-30% of systems, and C/O > 1.0 in ∼6%-10%. It has been suggested that in protoplanetary disks with C/O > 0.8 that the condensation pathways to refractory solids will differ from what occurred in our solar system, where C/O = 0.55. The carbon-rich disks are calculated to make carbon-dominated rocky planets, rather than oxygen-dominated ones. Here we suggest that the derived stellar C/O ratios are overestimated. One constraint on the frequency of high C/O is the relative paucity of carbon dwarf stars (10 –3 -10 –5 ) found in large samples of low-mass stars. We suggest reasons for this overestimation, including a high C/O ratio for the solar atmosphere model used for differential abundance analysis, the treatment of a Ni blend that affects the O abundance, and limitations of one-dimensional LTE stellar atmosphere models. Furthermore, from the estimated errors on the measured stellar C/O ratios, we find that the significance of the high C/O tail is weakened, with a true measured fraction of C/O > 0.8 in 10%-15% of stars, and C/O > 1.0 in 1%-5%, although these are still likely overestimates. We suggest that infrared T-dwarf spectra could show how common high C/O is in the stellar neighborhood, as the chemistry and spectra of such objects would differ compared to those with solar-like abundances. While possible at C/O > 0.8, we expect that carbon-dominated rocky planets are rarer than others have suggested.

  12. Carbon and oxygen isotope compositions of the carbonate facies

    Indian Academy of Sciences (India)

    The Vindhyan sedimentary succession in central India spans a wide time bracket from the Paleopro- terozoic to the Neoproterozoic period.Chronostratigraphic significance of stable carbon and oxygen isotope ratios of the carbonate phase in Vindhyan sediments has been discussed in some recent studies.However,the ...

  13. Insights into the importance of oxygen functional groups in carbon reactions with oxygen containing gases

    International Nuclear Information System (INIS)

    John Zhu, Max Lu

    2005-01-01

    treatment can significantly increase the amount of CO 2 -yielding functional groups (such as carboxyl and lactone groups) while HCl produced more unstable CO-yielding functional groups. The more powerful method for characterizing carbon surface functional groups may be DRIFT (Diffuse reflectance spectroscopy), which can distinguish types of functional groups effectively. To experimentally confirm the important roles of o-quinone and off-plane epoxy oxygen functional groups in gas-carbon reactions using DRIFT is currently under way in our group, which aims to gaining new insights into the importance of surface functional groups in gas-carbon reactions. Our generalized mechanism can also be extended to NO/N 2 O-carbon reactions, which can be successfully integrated into the random pore model by introducing a reactive site parameter B as a measure of the relative kinetic contributions from two different surface complexes. Its use in tandem with the pore structure parameter ψ is proposed as a means to achieving the much-desired integration of the theoretically derived pore structure models and fundamentally surface mechanism of carbon gasification reactions. Such fundamental studies are also providing strong support to the research on hydrogen storage by adsorption in carbon nano-materials. (authors)

  14. Kinetics of the exchange of oxygen between carbon dioxide and carbonate in aqueous solution

    International Nuclear Information System (INIS)

    Tu, C.K.; Silverman, D.N.

    1975-01-01

    A kinetic analysis of the exchange of oxygen between carbon dioxide and carbonate ion in alkaline, aqueous solutions is presented. The exchange was observed by placing 18 O-labeled carbonate, not enriched in 13 C, into solution with 13 C-enriched carbonate, not enriched in 18 O. The rate of depletion of 18 O from the 12 C-containing species and the rate of appearance of 18 O in the 13 C-containing species was measured by mass spectrometry. From these data, the second-order rate constant for the reaction between carbon dioxide and carbonate which results in the exchange of oxygen at 25 0 is 114 +- 11 M -1 sec -1 . It is emphasized that this exchange of oxygen between species of CO 2 in solution must be recognized in studies using 18 O labels to determine the fate of CO 2 in biochemical and physiological processes. (auth)

  15. Database of normal human cerebral blood flow, cerebral blood volume, cerebral oxygen extraction fraction and cerebral metabolic rate of oxygen measured by positron emission tomography with {sup 15}O-labelled carbon dioxide or water, carbon monoxide and oxygen: a multicentre study in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Hiroshi [Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita (Japan); Department of Nuclear Medicine and Radiology, Division of Brain Sciences, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-Machi, 980-8575, Aoba-Ku, Sendai (Japan); Kanno, Iwao [Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita (Japan); Kato, Chietsugu [Department of Nuclear Medicine, Hokkaido University School of Medicine, Sapporo (Japan); Sasaki, Toshiaki [Cyclotoron Research Center, Iwate Medical University, Morioka (Japan); Ishii, Kenji [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Tokyo (Japan); Ouchi, Yasuomi [Positron Medical Center, Hamamatsu Medical Center, Hamakita (Japan); Iida, Akihiko [Nagoya City Rehabilitation Center, Nagoya (Japan); Okazawa, Hidehiko [PET Unit, Research Institute, Shiga Medical Center, Moriyama (Japan); Hayashida, Kohei [Department of Radiology, National Cardiovascular Center, Suita, Osaka (Japan); Tsuyuguchi, Naohiro [Department of Neurosurgery, Osaka City University Medical School, Osaka (Japan); Ishii, Kazunari [Division of Imaging Research, Hyogo Institute for Aging Brain and Cognitive Disorders, Himeji, Hyogo (Japan); Kuwabara, Yasuo [Department of Radiology, Faculty of Medicine, Kyushu University, Fukuoka (Japan); Senda, Michio [Department of Image-based Medicine, Institute of Biomedical Research and Innovation, Kobe (Japan)

    2004-05-01

    Measurement of cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO{sub 2}) by positron emission tomography (PET) with oxygen-15 labelled carbon dioxide (C{sup 15}O{sub 2}) or {sup 15}O-labelled water (H{sub 2}{sup 15}O), {sup 15}O-labelled carbon monoxide (C{sup 15}O) and {sup 15}O-labelled oxygen ({sup 15}O{sub 2}) is useful for diagnosis and treatment planning in cases of cerebrovascular disease. The measured values theoretically depend on various factors, which may differ between PET centres. This study explored the applicability of a database of {sup 15}O-PET by examining between-centre and within-centre variation in values. Eleven PET centres participated in this multicentre study; seven used the steady-state inhalation method, one used build-up inhalation and three used bolus administration of C{sup 15}O{sub 2} (or H{sub 2}{sup 15}O) and {sup 15}O{sub 2}. All used C{sup 15}O for measurement of CBV. Subjects comprised 70 healthy volunteers (43 men and 27 women; mean age 51.8{+-}15.1 years). Overall mean{+-}SD values for cerebral cortical regions were: CBF=44.4{+-}6.5 ml 100 ml{sup -1} min{sup -1}; CBV=3.8{+-}0.7 ml 100 ml{sup -1}; OEF=0.44{+-}0.06; CMRO{sub 2}=3.3{+-}0.5 ml 100 ml{sup -1} min{sup -1}. Significant between-centre variation was observed in CBV, OEF and CMRO{sub 2} by one-way analysis of variance. However, the overall inter-individual variation in CBF, CBV, OEF and CMRO{sub 2} was acceptably small. Building a database of normal cerebral haemodynamics obtained by the{sup 15}O-PET methods may be practicable. (orig.)

  16. Measurement of carbon capture efficiency and stored carbon leakage

    Science.gov (United States)

    Keeling, Ralph F.; Dubey, Manvendra K.

    2013-01-29

    Data representative of a measured carbon dioxide (CO.sub.2) concentration and of a measured oxygen (O.sub.2) concentration at a measurement location can be used to determine whether the measured carbon dioxide concentration at the measurement location is elevated relative to a baseline carbon dioxide concentration due to escape of carbon dioxide from a source associated with a carbon capture and storage process. Optionally, the data can be used to quantify a carbon dioxide concentration increase at the first location that is attributable to escape of carbon dioxide from the source and to calculate a rate of escape of carbon dioxide from the source by executing a model of gas-phase transport using at least the first carbon dioxide concentration increase. Related systems, methods, and articles of manufacture are also described.

  17. Vibrationally Excited Carbon Monoxide Produced via a Chemical Reaction Between Carbon Vapor and Oxygen

    Science.gov (United States)

    Jans, Elijah R.; Eckert, Zakari; Frederickson, Kraig; Rich, Bill; Adamovich, Igor V.

    2017-06-01

    Measurements of the vibrational distribution function of carbon monoxide produced via a reaction between carbon vapor and molecular oxygen has shown a total population inversion on vibrational levels 4-7. Carbon vapor, produced using an arc discharge to sublimate graphite, is mixed with an argon oxygen flow. The excited carbon monoxide is vibrationally populated up to level v=14, at low temperatures, T=400-450 K, in a collision-dominated environment, 15-20 Torr, with total population inversions between v=4-7. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of the reaction enthalpy. Kinetic modeling of the flow reactor, including state specific vibrational processes, was performed to infer the vibrational distribution of the products of the reaction. The results show viability of developing of a new chemical CO laser from the reaction of carbon vapor and oxygen.

  18. Memristive effects in oxygenated amorphous carbon nanodevices

    Science.gov (United States)

    Bachmann, T. A.; Koelmans, W. W.; Jonnalagadda, V. P.; Le Gallo, M.; Santini, C. A.; Sebastian, A.; Eleftheriou, E.; Craciun, M. F.; Wright, C. D.

    2018-01-01

    Computing with resistive-switching (memristive) memory devices has shown much recent progress and offers an attractive route to circumvent the von-Neumann bottleneck, i.e. the separation of processing and memory, which limits the performance of conventional computer architectures. Due to their good scalability and nanosecond switching speeds, carbon-based resistive-switching memory devices could play an important role in this respect. However, devices based on elemental carbon, such as tetrahedral amorphous carbon or ta-C, typically suffer from a low cycling endurance. A material that has proven to be capable of combining the advantages of elemental carbon-based memories with simple fabrication methods and good endurance performance for binary memory applications is oxygenated amorphous carbon, or a-CO x . Here, we examine the memristive capabilities of nanoscale a-CO x devices, in particular their ability to provide the multilevel and accumulation properties that underpin computing type applications. We show the successful operation of nanoscale a-CO x memory cells for both the storage of multilevel states (here 3-level) and for the provision of an arithmetic accumulator. We implement a base-16, or hexadecimal, accumulator and show how such a device can carry out hexadecimal arithmetic and simultaneously store the computed result in the self-same a-CO x cell, all using fast (sub-10 ns) and low-energy (sub-pJ) input pulses.

  19. Oxygen evolution reaction in nanoconfined carbon nanotubes

    Science.gov (United States)

    Li, Ying; Lu, Xuefeng; Li, Yunfang; Zhang, Xueqing

    2018-05-01

    Improving oxygen electrochemistry through nanoscopic confinement has recently been highlighted as a promising strategy. In-depth understanding the role of confinement is therefore required. In this study, we simulate the oxygen evolution reaction (OER) on iron oxide nanoclusters under confinement of (7,7) and (8,8) armchair carbon nanotubes (CNTs). The free energies of the four proton coupled electron transfer (PCET) steps and the OER overpotentials are calculated. The Fe4O6 nanocluster confined in (7,7) CNT is found to be the most active for OER among the systems considered in this work. This leads to an increase in catalytic efficiency of OER compared to the hematite (110) surface, which was reported recently as an active surface towards OER. The calculated results show that the OER overpotential depends strongly on the magnetic properties of the iron oxide nanocluster. These findings are helpful for experimental design of efficient catalyst for water splitting applications.

  20. Phosphorus, and nitrogen co-doped carbon dots as a fluorescent probe for real-time measurement of reactive oxygen and nitrogen species inside macrophages.

    Science.gov (United States)

    Gong, Yunqian; Yu, Bin; Yang, Wen; Zhang, Xiaoling

    2016-05-15

    Phosphorus and nitrogen doped carbon dots (PN-CDs) were conveniently prepared by carbonization of adenosine-5'-triphosphate using a hydrothermal treatment. The PN-CDs with P/C atomic ratio of ca. 9.2/100 emit blue luminescence with high quantum yields of up to 23.5%. The PN-CDs were used as a novel sensing platform for live cell imaging of reactive oxygen species (ROS) and reactive nitrogen species (RNS), including ClO(-), ONOO(-), and NO in macrophages. The nanosensor design is based on our new finding that the strong fluorescence of the PN-CDs can be sensitively and selectively quenched by ROS and RNS both in vitro and in vivo. These results reveal that the PN-CDs can serve as a sensitive sensor for rapid imaging of ROS and RNS signaling with high selectivity and contrast. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Use of the Zetatron D-T neutron generator for the simultaneous measurement of carbon, oxygen, and hydrogen in vivo in humans

    International Nuclear Information System (INIS)

    Kehayias, J.J.; Zhuang, H.

    1993-01-01

    A small sealed D-T neutron generator is used for the pulsed (4-8 kHz) production of fast neutrons. Carbon and oxygen are detected in vivo by counting the 4.44 and 6.13 MeV gamma rays resulting from the inelastic scattering of the fast neutrons. Hydrogen is detected by thermal neutron capture. BGO detectors (127 mm diameter x 76 mm thick) were found more tolerant to neutron exposure and improved the signal to background ratio for the carbon detection by a factor of 6, compared to 152 x 152 mm NaI(Tl). The elemental analysis of the body is used to study the changes of body composition with aging. We investigate the causes of depletion of lean body mass and the development of ways of maintaining functional capacity and quality of life of the elderly. (orig.)

  2. Use of the Zetatron D-T neutron generator for the simultaneous measurement of carbon, oxygen, and hydrogen in vivo in humans

    Science.gov (United States)

    Kehayias, J. J.; Zhuang, H.

    1993-06-01

    A small sealed D-T neutron generator is used for the pulsed (4-8 kHz) production of fast neutrons. Carbon and oxygen are detected in vivo by counting the 4.44 and 6.13 MeV gamma rays resulting from the inelastic scattering of the fast neutrons. Hydrogen is detected by thermal neutron capture. BGO detectors (127 mm diameter × 76 mm thick) were found more tolerant to neutron exposure and improved the signal to background ratio for the carbon detection by a factor of 6, compared to 152 × 152 mm NaI(Tl). The elemental analysis of the body is used to study the changes of body composition with aging. We investigate the causes of depletion of lean body mass and the development of ways of maintaining functional capacity and quality of life of the elderly.

  3. The Range of 1-3 keV Electrons in Solid Oxygen and Carbon Monoxide

    DEFF Research Database (Denmark)

    Oehlenschlæger, M.; Andersen, H.H.; Schou, Jørgen

    1985-01-01

    The range of 1-3 keV electrons in films of solid oxygen and carbon monoxide has been measured by a mirror substrate method. The technique used here is identical to the one previously used for range measurements in solid hydrogen and nitrogen. The range in oxygen is slightly shorter than that in n......The range of 1-3 keV electrons in films of solid oxygen and carbon monoxide has been measured by a mirror substrate method. The technique used here is identical to the one previously used for range measurements in solid hydrogen and nitrogen. The range in oxygen is slightly shorter than...

  4. Oxygen activity measurements in simulated converter matte

    CSIR Research Space (South Africa)

    Tshilombo, KG

    2007-01-01

    Full Text Available to the composition of the gas atmosphere over the melt. The measured oxygen activity was generally close to that predicted by FactSage calculations. This indicates that such oxygen activity measurements could be useful to monitor iron removal during converting...

  5. Measurement of forearm oxygen consumption

    DEFF Research Database (Denmark)

    Astrup, A; Simonsen, L; Bülow, J

    1988-01-01

    The classical forearm technique widely used for studies of skeletal muscle metabolism requires arterial cannulation. To avoid arterial puncture it is becoming more common to arterialize blood from a contralateral hand vein by local heating. This modification and the classical method have produced...... blood flow and decreases skeletal muscle blood flow. This facilitates mixing of superficial blood with deep venous blood. Contralateral heating increased deep venous oxygen saturation and abolished the pronounced glucose-induced increase in oxygen consumption observed in the control experiments after...... contradictory results regarding the contribution of skeletal muscle to glucose-induced thermogenesis. The effect on forearm circulation and the metabolism of heating the contralateral hand was examined before and after an oral glucose load. The results suggest that contralateral heating increases subcutaneous...

  6. Carbon dioxide narcosis due to inappropriate oxygen delivery: a case report.

    Science.gov (United States)

    Herren, Thomas; Achermann, Eva; Hegi, Thomas; Reber, Adrian; Stäubli, Max

    2017-07-28

    Oxygen delivery to patients with chronic obstructive pulmonary disease may be challenging because of their potential hypoxic ventilatory drive. However, some oxygen delivery systems such as non-rebreathing face masks with an oxygen reservoir bag require high oxygen flow for adequate oxygenation and to avoid carbon dioxide rebreathing. A 72-year-old Caucasian man with severe chronic obstructive pulmonary disease was admitted to the emergency department because of worsening dyspnea and an oxygen saturation of 81% measured by pulse oximetry. Oxygen was administered using a non-rebreathing mask with an oxygen reservoir bag attached. For fear of removing the hypoxic stimulus to respiration the oxygen flow was inappropriately limited to 4L/minute. The patient developed carbon dioxide narcosis and had to be intubated and mechanically ventilated. Non-rebreathing masks with oxygen reservoir bags must be fed with an oxygen flow exceeding the patient's minute ventilation (>6-10 L/minute.). If not, the amount of oxygen delivered will be too small to effectively increase the arterial oxygen saturation. Moreover, the risk of carbon dioxide rebreathing dramatically increases if the flow of oxygen to a non-rebreathing mask is lower than the minute ventilation, especially in patients with chronic obstructive pulmonary disease and low tidal volumes. Non-rebreathing masks (with oxygen reservoir bags) must be used cautiously by experienced medical staff and with an appropriately high oxygen flow of 10-15 L/minute. Nevertheless, arterial blood gases must be analyzed regularly for early detection of a rise in partial pressure of carbon dioxide in arterial blood in patients with chronic obstructive pulmonary disease and a hypoxic ventilatory drive. These patients are more safely managed using a nasal cannula with an oxygen flow of 1-2L/minute or a simple face mask with an oxygen flow of 5L/minute.

  7. Carbon mineralization and oxygen dynamics in sediments with deep oxygen penetration, Lake Superior

    DEFF Research Database (Denmark)

    Li, Jiying; Crowe, Sean Andrew; Miklesh, David

    2012-01-01

    To understand carbon and oxygen dynamics in sediments with deep oxygen penetration, we investigated eight locations (160–318-m depth) throughout Lake Superior. Despite the 2–4 weight percent organic carbon content, oxygen penetrated into the sediment by 3.5 to > 12 cm at all locations. Such deep ...... volume-specific carbon degradation rates were 0.3–1.5 µmol cm−3 d−1; bioturbation coefficient near the sediment surface was 3–8 cm2 yr−1. These results indicate that carbon cycling in large freshwater systems conforms to many of the same trends as in marine systems.......To understand carbon and oxygen dynamics in sediments with deep oxygen penetration, we investigated eight locations (160–318-m depth) throughout Lake Superior. Despite the 2–4 weight percent organic carbon content, oxygen penetrated into the sediment by 3.5 to > 12 cm at all locations. Such deep......, suggesting that temporal variability in deeply oxygenated sediments may be greater than previously acknowledged. The oxygen uptake rates (4.4–7.7 mmol m−2 d−1, average 6.1 mmol m−2 d−1) and carbon mineralization efficiency (∼ 90% of deposited carbon) were similar to those in marine hemipelagic and pelagic...

  8. Oxygenation measurements in head and neck cancers during hyperbaric oxygenation

    International Nuclear Information System (INIS)

    Becker, A.; Kuhnt, T.; Dunst, J.; Liedtke, H.; Krivokuca, A.; Bloching, M.

    2002-01-01

    Background: Tumor hypoxia has proven prognostic impact in head and neck cancers and is associated with poor response to radiotherapy. Hyperbaric oxygenation (HBO) offers an approach to overcome hypoxia. We have performed pO 2 measurements in selected patients with head and neck cancers under HBO to determine in how far changes in the oxygenation occur and whether a possible improvement of oxygenation parameters is maintained after HBO. Patients and Methods: Seven patients (five male, two female, age 51-63 years) with squamous cell cancers of the head and neck were investigated (six primaries, one local recurrence). The median pO 2 prior to HBO was determined with the Eppendorf histograph. Sites of measurement were enlarged cervical lymph nodes (n = 5), the primary tumor (n = 1) and local recurrence (n = 1). Patients then underwent HBO (100% O 2 at 240 kPa for 30 minutes) and the continuous changes in the oxygenation during HBO were determined with a Licox probe. Patients had HBO for 30 minutes (n = 6) to 40 minutes (n = 1). HBO was continued because the pO 2 had not reached a steady state after 30 minutes. After decompression, patients ventilated pure oxygen under normobaric conditions and the course of the pO 2 was further measured over about 15 minutes. Results: Prior to HBO, the median tumor pO 2 in the Eppendorf histography was 8.6 ± 5.4 mm Hg (range 3-19 mm Hg) and the pO 2 measured with the Licox probe was 17.3 ± 25.5 mm Hg (range 0-73 mm Hg). The pO 2 increased significantly during HBO to 550 ± 333 mm Hg (range 85-984 mm Hg, p = 0.018). All patients showed a marked increase irrespective of the oxygenation prior to HBO. The maximum pO 2 in the tumor was reached after 10-33 minutes (mean 17 minutes). After leaving the hyperbaric chamber, the pO 2 was 282 ± 196 mm Hg. All patients maintained an elevated pO 2 for further 5-25 minutes (138 ± 128 mm Hg, range 42-334 mm Hg, p = 0.028 vs the pO 2 prior to HBO). Conclusions: Hyperbaric oxygenation resulted in a

  9. LBA-ECO CD-02 Carbon, Nitrogen, Oxygen Stable Isotopes in Organic Material, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set reports the measurement of stable carbon, nitrogen, and oxygen isotope ratios in organic material (plant, litter and soil samples) in forest canopy...

  10. LBA-ECO CD-02 Carbon, Nitrogen, Oxygen Stable Isotopes in Organic Material, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set reports the measurement of stable carbon, nitrogen, and oxygen isotope ratios in organic material (plant, litter and soil samples) in forest...

  11. Triple oxygen isotopes in biogenic and sedimentary carbonates

    Science.gov (United States)

    Passey, Benjamin H.; Hu, Huanting; Ji, Haoyuan; Montanari, Shaena; Li, Shuning; Henkes, Gregory A.; Levin, Naomi E.

    2014-09-01

    The 17O anomaly (Δ17O) of natural waters has been shown to be sensitive to evaporation in a way analogous to deuterium excess, with evaporated bodies of water (e.g., leaf waters, lake waters, animal body waters) tending to have lower Δ17O than primary meteoric waters. In animal body water, Δ17O relates to the intake of evaporated waters, evaporative effluxes of water, and the Δ17O value of atmospheric O2, which itself carries signatures of global carbon cycling and photochemical reactions in the stratosphere. Carbonates have the potential to record the triple oxygen isotope compositions of parent waters, allowing reconstruction of past water compositions, but such investigations have awaited development of methods for high-precision measurement of Δ17O of carbonate. We describe optimized methods based on a sequential acid digestion/reduction/fluorination approach that yield Δ17O data with the high precision (∼0.010‰, 1σ) needed to resolve subtle environmental signals. We report the first high-precision Δ17O dataset for terrestrial carbonates, focusing on vertebrate biogenic carbonates and soil carbonates, but also including marine invertebrates and high-temperature carbonates. We determine apparent three-isotope fractionation factors between the O2 analyte derived from carbonate and the parent waters of the carbonate. These in combination with appropriate temperature estimates (from clumped isotope thermometry, or known or estimated body temperatures) are used to calculate the δ18O and Δ17O of parent waters. The clearest pattern to emerge is the strong 17O-depletion in avian, dinosaurian, and mammalian body water (from analyses of eggshell and tooth enamel) relative to meteoric waters, following expected influences of evaporated water (e.g., leaf water) and atmospheric O2 on vertebrate body water. Parent waters of the soil carbonates studied here have Δ17O values that are similar to or slightly lower than global precipitation. Our results suggest

  12. Measurement of biological oxygen demand sandy beaches

    African Journals Online (AJOL)

    Measurements of biological oxygen demand in a sandy beach using conventional .... counting the cells present in a sample of aged seawater and comparing this with .... This activity peaked at 71 % above the undisturbed level after 16 hours.

  13. Oxygen measurements in thin ribbon silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hyland, S L; Ast, D G; Baghdadi, A

    1987-03-01

    The oxygen content of thin silicon ribbons grown by the dendritic web technique was measured using a modification of the ASTM method based on Fourier transform infrared spectroscopy. Web silicon was found to have a high oxygen content, ranging from 13 to 19 ppma, calculated from the absorption peak associated with interstitial oxygen and using the new ASTM conversion coefficient. The oxygen concentration changed by about 10% along the growth direction of the ribbon. In some samples, a shoulder was detected on the absorption peak. A similar shoulder in Czochralski grown material has been variously interpreted in the literature as due to a complex of silicon, oxygen, and vacancies, or to a phase of SiO/sub 2/ developed along dislocations in the material. In the case of web silicon, it is not clear which is the correct interpretation.

  14. A 1000-year record of dry conditions in the eastern Canadian prairies reconstructed from oxygen and carbon isotope measurements on Lake Winnipeg sediment organics

    Science.gov (United States)

    Buhay, W.M.; Simpson, S.; Thorleifson, H.; Lewis, M.; King, J.; Telka, A.; Wilkinson, Philip M.; Babb, J.; Timsic, S.; Bailey, D.

    2009-01-01

    A short sediment core (162 cm), covering the period AD 920-1999, was sampled from the south basin of Lake Winnipeg for a suite of multi-proxy analyses leading towards a detailed characterisation of the recent millennial lake environment and hydroclimate of southern Manitoba, Canada. Information on the frequency and duration of major dry periods in southern Manitoba, in light of the changes that are likely to occur as a result of an increasingly warming atmosphere, is of specific interest in this study. Intervals of relatively enriched lake sediment cellulose oxygen isotope values (??18Ocellulose) were found to occur from AD 1180 to 1230 (error range: AD 1104-1231 to 1160-1280), 1610-1640 (error range: AD 1571-1634 to 1603-1662), 1670-1720 (error range: AD 1643-1697 to 1692-1738) and 1750-1780 (error range: AD 1724-1766 to 1756-1794). Regional water balance, inferred from calculated Lake Winnipeg water oxygen isotope values (??18Oinf-lw), suggest that the ratio of lake evaporation to catchment input may have been 25-40% higher during these isotopically distinct periods. Associated with the enriched d??18Ocellulose intervals are some depleted carbon isotope values associated with more abundantly preserved sediment organic matter (d??13COM). These suggest reduced microbial oxidation of terrestrially derived organic matter and/or subdued lake productivity during periods of minimised input of nutrients from the catchment area. With reference to other corroborating evidence, it is suggested that the AD 1180-1230, 1610-1640, 1670-1720 and 1750-1780 intervals represent four distinctly drier periods (droughts) in southern Manitoba, Canada. Additionally, lower-magnitude and duration dry periods may have also occurred from 1320 to 1340 (error range: AD 1257-1363), 1530-1540 (error range: AD 1490-1565 to 1498-1572) and 1570-1580 (error range: AD 1531-1599 to 1539-1606). ?? 2009 John Wiley & Sons, Ltd.

  15. Electrochemical Reactor for Producing Oxygen From Carbon Dioxide, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — An electrochemical reactor is proposed by MicroCell Technologies, LLC to electrochemically reduce carbon dioxide to oxygen. In support of NASA's advanced life...

  16. Quantitative aspects of oxygen and carbon dioxide exchange ...

    African Journals Online (AJOL)

    Quantitative aspects of oxygen and carbon dioxide exchange through the ... ceratophthalmus (Crustacea: Decapoda) during rest and exercise in water and ... intersects zero time on the x-axis, indicating rapid gas exchange at the lung surface.

  17. Apparatus for simultaneously measuring electrical conductivity and oxygen fugacity

    Energy Technology Data Exchange (ETDEWEB)

    Netherton, R.; Duba, A.

    1978-01-31

    Electrical conductivity studies of silicates are useful in determining temperature vs depth in the earth. Realistic laboratory measurements of conduction mechanisms require that exact determinations of oxygen fugacity (fo{sub 2}) be made in the experimental environment. An apparatus is described that monitors system fo{sub 2} with a calcia-doped zirconia-oxygen cell while measuring electrical conductivity of iron-bearing silicates at high temperature (greater than 1000 K). The fo{sub 2} calculated thermodynamically from CO/CO{sub 2} mixing ratios agreed well with measurements made with the zirconia cell at 1473 K, except for fo{sub 2} greater than 10{sup -4} Pa, where, on a log{sub 10} scale, mixing-ratio errors were as large as +- 0.2. These errors are attributed to oxygen contamination in the CO{sub 2} and to mobile carbon deposits that formed in the apparatus.

  18. Kalahari groundwaters: Their hydrogen, carbon and oxygen isotopes

    International Nuclear Information System (INIS)

    Mazor, E.; Verhagen, B.T.; Sellschop, J.P.F.; Robins, N.S.; Hutton, L.G.

    1974-01-01

    Tritium and 14 C measurements have revealed several cases of post-nuclear bomb-test rain recharge of local groundwaters, along with values indicating recharge over larger, yet hydrologically active, time scales. In general, recharge seems to follow rain distribution in being more intense in the northern rather than in the southern Kalahari. Initial δ 13 C values vary over a wide range and reveal some correlation to pH and chemical composition of the water. They cannot be used to correct for fossil carbon dilution in 14 C-age calculations. Radiocarbon-deduced ages range from recent to 30,000 years. Stable hydrogen and oxygen isotopes indicate recharge from direct rain infiltration. (author)

  19. Agreement between arterial partial pressure of carbon dioxide and saturation of hemoglobin with oxygen values obtained by direct arterial blood measurements versus noninvasive methods in conscious healthy and ill foals.

    Science.gov (United States)

    Wong, David M; Alcott, Cody J; Wang, Chong; Bornkamp, Jennifer L; Young, Jessica L; Sponseller, Brett A

    2011-11-15

    To determine agreement between indirect measurements of end-tidal partial pressure of carbon dioxide (PetCO(2)) and saturation of hemoglobin with oxygen as measured by pulse oximetry (SpO(2)) with direct measurements of PaCO(2) and calculated saturation of hemoglobin with oxygen in arterial blood (SaO(2)) in conscious healthy and ill foals. Validation study. 10 healthy and 21 ill neonatal foals. Arterial blood gas analysis was performed on healthy and ill foals examined at a veterinary teaching hospital to determine direct measurements of PaCO(2) and PaO(2) along with SaO(2). Concurrently, PetCO(2) was measured with a capnograph inserted into a naris, and SpO(2) was measured with a reflectance probe placed at the base of the tail. Paired values were compared by use of Pearson correlation coefficients, and level of agreement was assessed with the Bland-Altman method. Mean ± SD difference between PaCO(2) and PetCO(2) was 0.1 ± 5.0 mm Hg. There was significant strong correlation (r = 0.779) and good agreement between PaCO(2) and PetCO(2). Mean ± SD difference between SaO(2) and SpO(2) was 2.5 ± 3.5%. There was significant moderate correlation (r = 0.499) and acceptable agreement between SaO(2) and SpO(2). Both PetCO(2) obtained by use of nasal capnography and SpO(2) obtained with a reflectance probe are clinically applicable and accurate indirect methods of estimating and monitoring PaCO(2) and SaO(2) in neonatal foals. Indirect methods should not replace periodic direct measurement of corresponding parameters.

  20. A metal-free electrocatalyst for carbon dioxide reduction to multi-carbon hydrocarbons and oxygenates

    Science.gov (United States)

    Wu, Jingjie; Ma, Sichao; Sun, Jing; Gold, Jake I.; Tiwary, ChandraSekhar; Kim, Byoungsu; Zhu, Lingyang; Chopra, Nitin; Odeh, Ihab N.; Vajtai, Robert; Yu, Aaron Z.; Luo, Raymond; Lou, Jun; Ding, Guqiao; Kenis, Paul J. A.; Ajayan, Pulickel M.

    2016-01-01

    Electroreduction of carbon dioxide into higher-energy liquid fuels and chemicals is a promising but challenging renewable energy conversion technology. Among the electrocatalysts screened so far for carbon dioxide reduction, which includes metals, alloys, organometallics, layered materials and carbon nanostructures, only copper exhibits selectivity towards formation of hydrocarbons and multi-carbon oxygenates at fairly high efficiencies, whereas most others favour production of carbon monoxide or formate. Here we report that nanometre-size N-doped graphene quantum dots (NGQDs) catalyse the electrochemical reduction of carbon dioxide into multi-carbon hydrocarbons and oxygenates at high Faradaic efficiencies, high current densities and low overpotentials. The NGQDs show a high total Faradaic efficiency of carbon dioxide reduction of up to 90%, with selectivity for ethylene and ethanol conversions reaching 45%. The C2 and C3 product distribution and production rate for NGQD-catalysed carbon dioxide reduction is comparable to those obtained with copper nanoparticle-based electrocatalysts. PMID:27958290

  1. A metal-free electrocatalyst for carbon dioxide reduction to multi-carbon hydrocarbons and oxygenates

    Science.gov (United States)

    Wu, Jingjie; Ma, Sichao; Sun, Jing; Gold, Jake I.; Tiwary, Chandrasekhar; Kim, Byoungsu; Zhu, Lingyang; Chopra, Nitin; Odeh, Ihab N.; Vajtai, Robert; Yu, Aaron Z.; Luo, Raymond; Lou, Jun; Ding, Guqiao; Kenis, Paul J. A.; Ajayan, Pulickel M.

    2016-12-01

    Electroreduction of carbon dioxide into higher-energy liquid fuels and chemicals is a promising but challenging renewable energy conversion technology. Among the electrocatalysts screened so far for carbon dioxide reduction, which includes metals, alloys, organometallics, layered materials and carbon nanostructures, only copper exhibits selectivity towards formation of hydrocarbons and multi-carbon oxygenates at fairly high efficiencies, whereas most others favour production of carbon monoxide or formate. Here we report that nanometre-size N-doped graphene quantum dots (NGQDs) catalyse the electrochemical reduction of carbon dioxide into multi-carbon hydrocarbons and oxygenates at high Faradaic efficiencies, high current densities and low overpotentials. The NGQDs show a high total Faradaic efficiency of carbon dioxide reduction of up to 90%, with selectivity for ethylene and ethanol conversions reaching 45%. The C2 and C3 product distribution and production rate for NGQD-catalysed carbon dioxide reduction is comparable to those obtained with copper nanoparticle-based electrocatalysts.

  2. First kinetic discrimination between carbon and oxygen reactivity of enols.

    Science.gov (United States)

    García-Río, Luis; Mejuto, Juan C; Parajó, Mercedes; Pérez-Lorenzo, Moisés

    2008-11-07

    Nitrosation of enols shows a well-differentiated behavior depending on whether the reaction proceeds through the carbon (nucleophilic catalysis is observed) or the oxygen atom (general acid-base catalysis is observed). This is due to the different operating mechanisms for C- and O-nitrosation. Nitrosation of acetylacetone (AcAc) shows a simultaneous nucleophilic and acid-base catalysis. This simultaneous catalysis constitutes the first kinetic evidence of two independent reactions on the carbon and oxygen atom of an enol. The following kinetic study allows us to determine the rate constants for both reaction pathways. A similar reactivity of the nucleophilic centers with the nitrosonium ion is observed.

  3. Chemical recycling of carbon fibers reinforced epoxy resin composites in oxygen in supercritical water

    International Nuclear Information System (INIS)

    Bai, Yongping; Wang, Zhi; Feng, Liqun

    2010-01-01

    The carbon fibers in carbon fibers reinforced epoxy resin composites were recovered in oxygen in supercritical water at 30 ± 1 MPa and 440 ± 10 o C. The microstructure of the recovered carbon fibers was observed using scanning electron microscopy (SEM) and atom force microscopy (AFM). The results revealed that the clean carbon fibers were recovered and had higher tensile strength relative to the virgin carbon fibers when the decomposition rate was above 85 wt.%, although the recovered carbon fibers have clean surface, the epoxy resin on the surface of the recovered carbon fibers was readily observed. As the decomposition rate increased to above 96 wt.%, no epoxy resin was observed on the surface of the carbon fibers and the oxidation of the recovered carbon fibers was readily measured by X-ray photoelectron spectroscopy (XPS) analysis. The carbon fibers were ideally recovered and have original strength when the decomposition rates were between 94 and 97 wt.%. This study clearly showed the oxygen in supercritical water is a promising way for recycling the carbon fibers in carbon fibers reinforced resin composites.

  4. The monitoring of oxygen, hydrogen and carbon in the sodium circuits of the PFR

    International Nuclear Information System (INIS)

    Mason, L.; Morrison, N.S.; Robertson, C.M.; Trevillion, E.A.

    1984-01-01

    The paper reviews the instrumentation available for monitoring oxygen, hydrogen, tritium and carbon impurity levels on the primary and secondary circuits of PFR. Circuit oxygen levels measured using electrochemical oxygen meters are compared to estimates from circuit plugging meters. The data are interpreted in the light of information from cold trap temperatures. Measurements of secondary circuit hydrogen levels using both the sodium and gas phase hydrogen detection equipment are compared to estimates of circuit hydrogen levels from plugging meters and variations in sodium phase hydrogen levels during power operation are discussed. (author)

  5. Hydrogen Oxidation on Gas Diffusion Electrodes for Phosphoric Acid Fuel Cells in the Presence of Carbon Monoxide and Oxygen

    DEFF Research Database (Denmark)

    Gang, Xiao; Li, Qingfeng; Hjuler, Hans Aage

    1995-01-01

    Hydrogen oxidation has been studied on a carbon-supported platinum gas diffusion electrode in a phosphoric acidelectrolyte in the presence of carbon monoxide and oxygen in the feed gas. The poisoning effect of carbon monoxide presentin the feed gas was measured in the temperature range from 80...... to 150°C. It was found that throughout the temperaturerange, the potential loss due to the CO poisoning can be reduced to a great extent by the injection of small amounts ofgaseous oxygen into the hydrogen gas containing carbon monoxide. By adding 5 volume percent (v/o) oxygen, an almost...

  6. Correlation analysis of Carbon Dioxide, Oxygen, Temperature and Humidity of Yadavaran Oil field in Khuzestan province

    Directory of Open Access Journals (Sweden)

    Mohammad velayatzadeh

    2018-02-01

    Full Text Available Background & Objective:Emission of Carbon dioxide in the atmosphere has an important role in increasing temperatures and, its higher concentration can effect on human health. Due to this issue, this study is aimed to measure the amount of the released carbon dioxide into the atmosphere in different part of Yadavaran Oil field and compare with international standards in 2017. Material & Methods:The present investigation was accomplished in Yadavaran oil field of Khuzestan province of Iran in 2017. In this study measurement of parameters including carbon dioxide, carbon monoxide, oxygen, relative humidity and temperature was done in 64 stations with 3 replications using ALTAIR 4X and Trotec BZ30. Data was analyzed by one-way ANOVA and Kolmogorov–Smirnov tests. Moreover, Correlation analysis was performed using Pearson and Spearman coefficients. Results:The results showed that concentration range of carbon dioxide and oxygen was 490-590 and 19-208ppm respectively. Also, the highest and lowest levels of carbon dioxide were 584.56±6.36 and 453.94±77.7 ppm in wet water camp and S10 wells (P 0.05 in the same order. Conclusion:Pearson and Spearman coefficient analysis showed no significant correlation between temperature, humidity, oxygen and carbon dioxide. According to the results, the concentration of carbon dioxide in different areas of the oil field of Yadavaran was acceptable.

  7. Oxygen etching mechanism in carbon-nitrogen (CNx) domelike nanostructures

    International Nuclear Information System (INIS)

    Acuna, J. J. S.; Figueroa, C. A.; Kleinke, M. U.; Alvarez, F.; Biggemann, D.

    2008-01-01

    We report a comprehensive study involving the ion beam oxygen etching purification mechanism of domelike carbon nanostructures containing nitrogen. The CN x nanodomes were prepared on Si substrate containing nanometric nickel islands catalyzed by ion beam sputtering of a carbon target and assisting the deposition by a second nitrogen ion gun. After preparation, the samples were irradiated in situ by a low energy ion beam oxygen source and its effects on the nanostructures were studied by x-ray photoelectron spectroscopy in an attached ultrahigh vacuum chamber, i.e., without atmospheric contamination. The influence of the etching process on the morphology of the samples and structures was studied by atomic force microscopy and field emission gun-secondary electron microscopy, respectively. Also, the nanodomes were observed by high resolution transmission electron microscopy. The oxygen atoms preferentially bond to carbon atoms by forming terminal carbonyl groups in the most reactive parts of the nanostructures. After the irradiation, the remaining nanostructures are grouped around two well-defined size distributions. Subsequent annealing eliminates volatile oxygen compounds retained at the surface. The oxygen ions mainly react with nitrogen atoms located in pyridinelike structures

  8. 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 ...

  9. 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 ...

  10. Ethanol flame synthesis of carbon nanotubes in deficient oxygen environments

    Science.gov (United States)

    Hu, Wei-Chieh; Lin, Ta-Hui

    2016-04-01

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

  11. Measuring oxidation processes: Atomic oxygen flux monitor

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Of the existing 95 high-energy accelerators in the world, the Stanford Linear Collider (SLC) at the Stanford Linear Accelerator Center (SLAC) is the only one of the linear-collider type, where electrons and positrons are smashed together at energies of 50 GeV using linear beams instead of beam rings for achieving interactions. Use of a collider eliminates energy losses in the form of x-rays due to the curved trajectory of the rings, a phenomena known as bremsstrauhlung. Because these losses are eliminated, higher interaction energies are reached. Consequently the SLC produced the first Z particle in quantities large enough to allow measurement of its physical properties with some accuracy. SLAC intends to probe still deeper into the structure of matter by next polarizing the electrons in the beam. The surface of the source for these polarized particles, typically gallium arsenide, must be kept clean of contaminants. One method for accomplishing this task requires the oxidation of the surface, from which the oxidized contaminants are later boiled off. The technique requires careful measurement of the oxidation process. SLAC researchers have developed a technique for measuring the atomic oxygen flux in this process. The method uses a silver film on a quartz-crystal, deposition-rate monitor. Measuring the initial oxidation rate of the silver, which is proportional to the atomic oxygen flux, determines a lower limit on that flux in the range of 10 13 to 10 17 atoms per square centimeter per second. Furthermore, the deposition is reversible by exposing the sensor to atomic hydrogen. This technique has wider applications to processes in solid-state and surface physics as well as surface chemistry. In semiconductor manufacturing where a precise thickness of oxide must be deposited, this technique could be used to monitor the critical flux of atomic oxygen in the process

  12. The Role of Oxygen Therapies in Carbon Monoxide Poisoning

    Directory of Open Access Journals (Sweden)

    Suleyman Metin

    2011-08-01

    Full Text Available Due to climate and socio-economic issues in Turkey, the incidence of carbon monoxide (CO poisoning is high, especially in winter. Clinical manifestations may vary depending on the type of CO source, concentration and duration of exposure. The symptoms of CO poisoning predominantly manifest in lots of organs and systems with high oxygen utilization, especially the brain and the heart. The primary aim in oxygen therapy is to eliminate CO and to reduce its toxic effects. In this context, normobaric and hyperbaric oxygen therapy are used to achieve these goals. Normobaric oxygen (NBO treatment is an easily accessible and relatively not expensive modality, where hyperbaric oxygen (HBO therapy requires specific equipment, certified staff and is available only in some centers. Additionally, HBO treatment has several additional advantages over NBO treatment. Despite its benefits, it is compulsory to search for some criteria in selecting patients to be treated because of the limited availability and access of hyperbaric facilities. For an effective evaluation and an optimal treatment, advanced education of the healthcare professionals on the use of oxygen delivery modalities in the management of CO poisoning is imperative. In this review, it has been aimed to outline the significance of oxygen treatment modalities and to determine patient selection criteria for HBO treatment in the management of CO poisoning which continues to be an important threat to community health care. [TAF Prev Med Bull 2011; 10(4.000: 487-494

  13. Clinical oxygen enhancement ratio of tumors in carbon ion radiotherapy: the influence of local oxygenation changes

    DEFF Research Database (Denmark)

    Antonovic, Laura; Lindblom, Emely; Dasu, Alexandru

    2014-01-01

    , using the repairable–conditionally repairable (RCR) damage model with parameters for human salivary gland tumor cells. The clinical oxygen enhancement ratio (OER) was defined as the ratio of doses required for a tumor control probability of 50% for hypoxic and well-oxygenated tumors. The resulting OER...... was well above unity for all fractionations. For the hypoxic tumor, the tumor control probability was considerably higher if LOCs were assumed, rather than static oxygenation. The beneficial effect of LOCs increased with the number of fractions. However, for very low fraction doses, the improvement related...... to LOCs did not compensate for the increase in total dose required for tumor control. In conclusion, our results suggest that hypoxia can influence the outcome of carbon ion radiotherapy because of the non-negligible oxygen effect at the low LETs in the SOBP. However, if LOCs occur, a relatively high...

  14. Oxygen Measurements in Liposome Encapsulated Hemoglobin

    Science.gov (United States)

    Phiri, Joshua Benjamin

    Liposome encapsulated hemoglobins (LEH's) are of current interest as blood substitutes. An analytical methodology for rapid non-invasive measurements of oxygen in artificial oxygen carriers is examined. High resolution optical absorption spectra are calculated by means of a one dimensional diffusion approximation. The encapsulated hemoglobin is prepared from fresh defibrinated bovine blood. Liposomes are prepared from hydrogenated soy phosphatidylcholine (HSPC), cholesterol and dicetylphosphate using a bath sonication method. An integrating sphere spectrophotometer is employed for diffuse optics measurements. Data is collected using an automated data acquisition system employing lock-in -amplifiers. The concentrations of hemoglobin derivatives are evaluated from the corresponding extinction coefficients using a numerical technique of singular value decomposition, and verification of the results is done using Monte Carlo simulations. In situ measurements are required for the determination of hemoglobin derivatives because most encapsulation methods invariably lead to the formation of methemoglobin, a nonfunctional form of hemoglobin. The methods employed in this work lead to high resolution absorption spectra of oxyhemoglobin and other derivatives in red blood cells and liposome encapsulated hemoglobin (LEH). The analysis using singular value decomposition method offers a quantitative means of calculating the fractions of oxyhemoglobin and other hemoglobin derivatives in LEH samples. The analytical methods developed in this work will become even more useful when production of LEH as a blood substitute is scaled up to large volumes.

  15. Pharmaceutical preparation of oxygen-15 labelled molecular oxygen and carbon monoxide gasses in a hospital setting.

    NARCIS (Netherlands)

    Luurtsema, Geert; Boellaard, Ronald; Greuter, Henri; Rijbroek, Abraham; Takkenkamp, Kevin; de Geest, Frank; Buijs, Fred; Hendrikse, NH; Franssen, Eric; van Lingen, Arthur; Lammertsma, Adriaan A.

    BACKGROUND: Clinical positron emission tomography (PET) requires safe and effective PET radiopharmaceuticals. Tracers used for measuring oxygen consumption and blood volume are [(15)O]O(2) and [(15)O]CO, respectively. In general, these oxygen-15 labelled tracers are produced using a cyclotron that

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

    International Nuclear Information System (INIS)

    Vizkelethy, G.; Revesz, P.

    1993-01-01

    The quantification of oxygen and carbon in high-temperature (T c ) superconducting oxide thin films was made by employing elastic resonance in He backscattering analysis. A method combining the oxygen resonance technique and channeling was presented for measuring the nature of the oxygen disorder near the surface and the interface in a YBCO superconducting film grown on an MgO substrate. The oxygen resonance technique was used to quantify the oxygen profiling in the metal/YBCO contacts, showing that Zr and Nb act as sinks to oxygen from YBCO films and are oxidized in the forms Zr/ZrO 2 /YBCO/MgO and Nb 0.2 O/YBCO/MgO after annealing in a vacuum at 350 o C. We combined the carbon and oxygen resonances to determine the carbon contamination and oxygen concentration changes on the YBCO surface after coating and baking the photoresist. Residual carbon on the surface and a thin layer of oxygen depletion near the YBCO surface have been observed. The residual carbon in Bi 2 Sr 2 CaCu 2 O 8 films made by the decomposition of metallo-organic precursors was quantified using carbon resonance. (author)

  17. Emissions & Measurements - Black Carbon

    Science.gov (United States)

    Emissions and Measurement (EM) research activities performed within the National Risk Management Research Lab NRMRL) of EPA's Office of Research and Development (ORD) support measurement and laboratory analysis approaches to accurately characterize source emissions, and near sour...

  18. Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model.

    Science.gov (United States)

    Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

    2016-01-01

    The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin.

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

    DEFF Research Database (Denmark)

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

    1999-01-01

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

  20. Water self-diffusion through narrow oxygenated carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Striolo, Alberto [School of Chemical Biological and Materials Engineering, University of Oklahoma, Norman, OK 73019 (United States)

    2007-11-28

    The hydrophobic interior of carbon nanotubes, which is reminiscent of ion channels in cellular membranes, has inspired scientific research directed towards the production of, for example, membranes for water desalination, drug-delivery devices, and nanosyringes. To develop these technologies it is crucial to understand and predict the equilibrium and transport properties of confined water. We present here a series of molecular dynamics simulation results conducted to understand the extent to which the presence of a few oxygenated active sites, modeled as carbonyls, affects the transport properties of confined water. The model for the carbon nanotube is not intended to be realistic. Its only purpose is to allow us to understand the effect of a few oxygenated sites on the transport properties of water confined in a narrow cylindrical pore, which is otherwise hydrophobic. At low hydration levels we found little, if any, water diffusion. The diffusion, which appears to be of the Fickian type for sufficiently large hydration levels, becomes faster as the number of confined water molecules increases, reaches a maximum, and slows as water fills the carbon nanotubes. We explain our findings on the basis of two collective motion mechanisms observed from the analysis of sequences of simulation snapshots. We term the two mechanisms 'cluster-breakage' and 'cluster-libration' mechanisms. We observe that the cluster-breakage mechanism produces longer displacements for the confined water molecules than the cluster-libration one, but deactivates as water fills the carbon nanotube. From a practical point of view, our results are particularly important for two reasons: (1) at low hydration levels the presence of only eight carbonyl groups can prevent the diffusion of water through (8, 8) carbon nanotubes; and (2) the extremely fast self-diffusion coefficients observed for water within narrow carbon nanotubes are significantly decreased in the presence of only a

  1. Water self-diffusion through narrow oxygenated carbon nanotubes

    International Nuclear Information System (INIS)

    Striolo, Alberto

    2007-01-01

    The hydrophobic interior of carbon nanotubes, which is reminiscent of ion channels in cellular membranes, has inspired scientific research directed towards the production of, for example, membranes for water desalination, drug-delivery devices, and nanosyringes. To develop these technologies it is crucial to understand and predict the equilibrium and transport properties of confined water. We present here a series of molecular dynamics simulation results conducted to understand the extent to which the presence of a few oxygenated active sites, modeled as carbonyls, affects the transport properties of confined water. The model for the carbon nanotube is not intended to be realistic. Its only purpose is to allow us to understand the effect of a few oxygenated sites on the transport properties of water confined in a narrow cylindrical pore, which is otherwise hydrophobic. At low hydration levels we found little, if any, water diffusion. The diffusion, which appears to be of the Fickian type for sufficiently large hydration levels, becomes faster as the number of confined water molecules increases, reaches a maximum, and slows as water fills the carbon nanotubes. We explain our findings on the basis of two collective motion mechanisms observed from the analysis of sequences of simulation snapshots. We term the two mechanisms 'cluster-breakage' and 'cluster-libration' mechanisms. We observe that the cluster-breakage mechanism produces longer displacements for the confined water molecules than the cluster-libration one, but deactivates as water fills the carbon nanotube. From a practical point of view, our results are particularly important for two reasons: (1) at low hydration levels the presence of only eight carbonyl groups can prevent the diffusion of water through (8, 8) carbon nanotubes; and (2) the extremely fast self-diffusion coefficients observed for water within narrow carbon nanotubes are significantly decreased in the presence of only a few oxygenated active

  2. Isotopes of carbon and oxygen in the carbonate impurities of coal have potential as palaeoenvironmental indicators

    International Nuclear Information System (INIS)

    Verhagen, B.T.; Falcon, R.M.

    1990-01-01

    The nature and systematics of impurities such as carbonates need to be established in order to understand their provenance in coal seams with reference to mining, beneficiation and ultimately their elimination or reduction. To this end, mineralogical and carbon-13 and oxygen-18 isotopic studies were undertaken on carbonate occurrences in coal from the eastern Transvaal highveld. Isotopic variations of considerable amplitude and individual values of extreme ''lightness'' are to be found in the carbonates in coal of the Witbank and adjacent basins. The observed isotopic ratios have a clear bearing on the nature and origins of the carbonates. 1 tab., 1 fig

  3. Geomagnetically trapped carbon, nitrogen, and oxygen nuclei.

    Science.gov (United States)

    Mogro-Campero, A.

    1972-01-01

    Results of measurements carried out with the University of Chicago nuclear composition telescope on the Ogo 5 satellite, establishing the presence of 13- to 33-MeV/nucleon geomagnetically trapped C and O nuclei, with some evidence for N nuclei. These trapped nuclei were found at L less than or equal to 5 and near the geomagnetic equator. The data cover the period from Mar. 3, 1968, to Dec. 31, 1969. The distribution of CNO flux as a function of L is given. No change in the intensity of the average trapped CNO flux was detected by comparing data for 1968 and 1969. The results reported set a new value for the observed high energy limit of trapping as described by the critical adiabaticity parameter. The penetration of solar flare CNO up to L = 4 was observed twice in 1968, in disagreement with Stormer theory predictions. The effects of these results on some models for the origin of the trapped radiation are discussed.

  4. Crystallization of carbon-oxygen mixtures in white dwarf stars.

    Science.gov (United States)

    Horowitz, C J; Schneider, A S; Berry, D K

    2010-06-11

    We determine the phase diagram for dense carbon-oxygen mixtures in white dwarf (WD) star interiors using molecular dynamics simulations involving liquid and solid phases. Our phase diagram agrees well with predictions from Ogata et al. and from Medin and Cumming and gives lower melting temperatures than Segretain et al. Observations of WD crystallization in the globular cluster NGC 6397 by Winget et al. suggest that the melting temperature of WD cores is close to that for pure carbon. If this is true, our phase diagram implies that the central oxygen abundance in these stars is less than about 60%. This constraint, along with assumptions about convection in stellar evolution models, limits the effective S factor for the 12C(α,γ)16O reaction to S(300)≤170  keV b.

  5. Differences in temperature, organic carbon and oxygen consumption among lowland streams

    DEFF Research Database (Denmark)

    Sand-Jensen, K.; Pedersen, N. L.

    2005-01-01

    1. Temperature, organic carbon and oxygen consumption were measured over a year at 13 sites in four lowlands streams within the same region in North Zealand, Denmark with the objectives of determining: (i) spatial and seasonal differences between open streams, forest streams and streams with or w......1. Temperature, organic carbon and oxygen consumption were measured over a year at 13 sites in four lowlands streams within the same region in North Zealand, Denmark with the objectives of determining: (i) spatial and seasonal differences between open streams, forest streams and streams...... the exponential increase of oxygen consumption rate between 4 and 20 °C averaged 0.121 °C-1 (Q10 of 3.35) in 70 measurements and showed no significant variations between seasons and stream sites or correlations with ambient temperature and organic content. 5. Oxygen consumption rate was enhanced downstream...... at ambient temperature by 30-40% and 80-130%, respectively. Faster consumption of organic matter and dissolved oxygen downstream of point sources should increase the likelihood of oxygen stress of the stream biota and lead to the export of less organic matter but more mineralised nutrients to the coastal...

  6. Activated carbon oxygen content influence on water and surfactant adsorption.

    Science.gov (United States)

    Pendleton, Phillip; Wu, Sophie Hua; Badalyan, Alexander

    2002-02-15

    This research investigates the adsorption properties of three activated carbons (AC) derived from coconut, coal, and wood origin. Each carbon demonstrates different levels of resistance to 2 M NaOH treatment. The coconut AC offers the greatest and wood AC the least resistance. The influence of base treatment is mapped in terms of its effects on specific surface area, micropore volume, water adsorption, and dodecanoic acid adsorption from both water and 2 M NaOH solution. A linear relationship exists between the number of water molecules adsorbed at the B-point of the water adsorption isotherm and the oxygen content determined from elemental analysis. Surfactant adsorption isotherms from water and 2 M NaOH indicate that the AC oxygen content effects a greater dependence on affinity for surfactant than specific surface area and micropore volume. We show a linear relationship between the plateau amount of surfactant adsorbed and the AC oxygen content in both water and NaOH phases. The higher the AC oxygen content, the lower the amount of surfactant adsorbed. In contrast, no obvious relationship could be drawn between the surfactant amount adsorbed and the surface area.

  7. Oxygen-carbon nanotubes as a chemotherapy sensitizer for paclitaxel in breast cancer treatment.

    Directory of Open Access Journals (Sweden)

    Yongkun Wang

    Full Text Available To study the in vivo and in vitro effects of adding oxygen carbon nanotubes (CNTs to chemotherapy for breast cancer.MCF-7 and SK-BR-3 breast cancer cells were co-cultured with paclitaxel and then exposed to oxygen-CNTs under hypoxic conditions. Cell proliferation, viability, and apoptosis rate were analyzed. Hypoxia-inducible factor-1 alpha (HIF-1α expression was measured using reverse transcription-polymerase chain reaction (RT-PCR and western blot. Nude mice were used as a human breast cancer model to explore the impact of oxygen-CNTs on the in vivo chemotherapeutic effect of paclitaxel.Oxygen-CNTs had no significant effects on the growth of breast cancer cells under normoxia and hypoxia. However, in the hypoxic environment, oxygen-CNTs significantly enhanced the inhibitory effect of paclitaxel on cell proliferation, as well as the apoptosis rate. Under hypoxia, downregulation of HIF-1α and upregulation of caspase-3, caspase-8, caspase-9, LC3 and Beclin-1 were observed when paclitaxel was combined with oxygen-CNT. Furthermore, addition of oxygen-CNTs to chemotherapy was found to significantly reduce tumor weight in the tumor-bearing mice model.Oxygen-CNTs can significantly increase the chemotherapeutic effect of paclitaxel on breast cancer cells. Oxygen-CNTs may be a potential chemosensitizer in breast cancer therapy.

  8. Amperometric micro pH measurements in oxygenated saliva.

    Science.gov (United States)

    Chaisiwamongkhol, Korbua; Batchelor-McAuley, Christopher; Compton, Richard G

    2017-07-24

    An amperometric micro pH sensor has been developed based on the chemical oxidation of carbon fibre surfaces (diameter of 9 μm and length of ca. 1 mm) to enhance the population of surface quinone groups for the measurement of salivary pH. The pH analysis utilises the electrochemically reversible two-electron, two-proton behaviour of surface quinone groups on the micro-wire electrodes. A Nernstian response is observed across the pH range 2-8 which is the pH range of many biological fluids. We highlight the measurement of pH in small volumes of biological fluids without the need for oxygen removal and specifically the micro pH electrode is examined by measuring the pH of commercial synthetic saliva and authentic human saliva samples. The results correspond well with those obtained by using commercial glass pH electrodes on large volume samples.

  9. Measurement of oxygen transfer from air into organic solvents

    DEFF Research Database (Denmark)

    Ramesh, Hemalata; Mayr, Torsten; Hobisch, Mathias

    2016-01-01

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

  10. Nitric oxide and carbon monoxide diffusing capacity after a 1-h oxygen dive to 9 m of sea water

    NARCIS (Netherlands)

    van Ooij, P. J. A. M.; van Hulst, R. A.; Houtkooper, A.; Sterk, P. J.

    2014-01-01

    To prevent extensive pulmonary lesions in submerged oxygen divers lung function like the forced vital capacity (FVC) or the diffusing capacity for carbon monoxide (DL,co) are used to monitor pulmonary oxygen toxicity (POT). As the diffusing capacity for nitric oxide (DL,no) measures more accurately

  11. Calculation on uranium carbon oxygen system molecular structure by DFT

    International Nuclear Information System (INIS)

    Zhang Guangfeng; Wang Xiaolin; Zou Lexi; Sun Ying; Xue Weidong; Zhu Zhenghe; Wang Hongyan

    2001-01-01

    The authors study on the possible molecular structures U-C-O, U-O-C, C-U-O (angular structure C a nd linear structure C ∞υ ) of carbon monoxide interacting on uranium metal surface by Density functional theory (DFT). The uranium atom is used RECP (Relativistic Effective Core Potential) and contracted valence basis sets (6s5p2d4f)/[3s3p2d2f], and for carbon and oxygen atoms all are 6-311G basis sets. The author presents the results of energy optimum which shows that triple and quintuple state are more stable. The authors get the electronic state, geometry structure, energy, harmonic frequency, mechanical property, etc. of these twelve triple and quintuple state relative stable structures. The normal vibrational analytical figure of angular structure (C s ) and linear structure (C ∞υ ) is given at the same time. It is indicated that angular structure has lower energy than linear structure, moreover the angular structure of U-C-O( 3 A ) has the lowest energy. The bond strength between uranium atom and carbon monoxide is weak and between uranium atom and oxygen atom is slightly stronger than between uranium atom and carbon atom which the authors can know by superposition population and bond energy analysis among atoms

  12. Quantitative Measurement of Oxygen in Microgravity Combustion

    Science.gov (United States)

    Silver, Joel A.

    1997-01-01

    A low-gravity environment, in space or in ground-based facilities such as drop towers, provides a unique setting for studying combustion mechanisms. Understanding the physical phenomena controlling the ignition and spread of flames in microgravity has importance for space safety as well as for better characterization of dynamical and chemical combustion processes which are normally masked by buoyancy and other gravity-related effects. Due to restrictions associated with performing measurements in reduced gravity, diagnostic methods which have been applied to microgravity combustion studies have generally been limited to capture of flame emissions on film or video, laser Schlieren imaging and (intrusive) temperature measurements using thermocouples. Given the development of detailed theoretical models, more sophisticated diagnostic methods are needed to provide the kind of quantitative data necessary to characterize the properties of microgravity combustion processes as well as provide accurate feedback to improve the predictive capabilities of the models. When the demands of space flight are considered, the need for improved diagnostic systems which are rugged, compact, reliable, and operate at low power becomes apparent. The objective of this research is twofold. First, we want to develop a better understanding of the relative roles of diffusion and reaction of oxygen in microgravity combustion. As the primary oxidizer species, oxygen plays a major role in controlling the observed properties of flames, including flame front speed (in solid or liquid flames), extinguishment characteristics, flame size and flame temperature. The second objective is to develop better diagnostics based on diode laser absorption which can be of real value in both microgravity combustion research and as a sensor on-board Spacelab as either an air quality monitor or as part of a fire detection system. In our prior microgravity work, an eight line-of-sight fiber optic system measured

  13. The effect of carbon and boron on the accumulation of vacancy-oxygen complexes in silicon

    International Nuclear Information System (INIS)

    Akhmetov, V.D.; Bolotov, V.V.

    1980-01-01

    By means of IR-absorption measurements the dose dependencies of the concentrations of vacancy-oxygen complexes (VO), interstitial oxygen atoms (Osub(I)), substitutional carbon atoms (Csub(S)) and interstitial carbon-oxygen complexes (Csub(I)Osub(I)) in n- and p-type silicon irradiated with 1.1 MeV electrons have been investigated. The observed increase of the production rate of VO-complexes with the rise of carbon and boron atoms concentrations (these impurities act as sinks for silicon interstitial atoms) has been explained in terms of annihilation of the vacancies and interstitials on the oxygen atoms. The results obtained show that boron atoms are more effective sinks than carbon atoms for the interstitial silicon atoms. That seems to be connected not only with the higher probability of boron injection into interstitial position but also with the further capture of interstitial silicon atoms on the interstitial boron, i.e. with the interstitial cluster formation. (author)

  14. Use of molecular oxygen to reduce EUV-induced carbon contamination of optics

    Science.gov (United States)

    Malinowski, Michael E.; Grunow, Philip A.; Steinhaus, Chip; Clift, W. Miles; Klebanoff, Leonard E.

    2001-08-01

    Carbon deposition and removal experiments on Mo/Si multilayer mirror (MLM) samples were performed using extreme ultraviolet (EUV) light on Beamline 12.0.1.2 of the Advanced Light Source, Lawrence Berkeley National Laboratory (LBNL). Carbon (C) was deposited onto Mo/Si multilayer mirror (MLM) samples when hydrocarbon vapors where intentionally introduced into the MLM test chamber in the presence of EUV at 13.44 nm (92.3eV). The carbon deposits so formed were removed by molecular oxygen + EUV. The MLM reflectivities and photoemission were measured in-situ during these carbon deposition and cleaning procedures. Auger Electron Spectroscopy (AES) sputter-through profiling of the samples was performed after experimental runs to help determine C layer thickness and the near-surface compositional-depth profiles of all samples studied. EUV powers were varied from ~0.2mW/mm2 to 3mW/mm2(at 13.44 nm) during both deposition and cleaning experiments and the oxygen pressure ranged from ~5x10-5 to 5x10-4 Torr during the cleaning experiments. C deposition rates as high as ~8nm/hr were observed, while cleaning rates as high as ~5nm/hr could be achieved when the highest oxygen pressure were used. A limited set of experiments involving intentional oxygen-only exposure of the MLM samples showed that slow oxidation of the MLM surface could occur.

  15. Carbon and Oxygen isotopic composition in paleoenvironmental determination

    International Nuclear Information System (INIS)

    Silva, J.R.M. da.

    1978-01-01

    This work reports that the carbon and oxygen isotopic composition separate the mollusks from marine environment of the mollusks from continental environment in two groups isotopically different, making the biological control outdone by environment control, in the isotopic fragmentation mechanisms. The patterns from the continental environment are more rich in O 16 than the patterns from marine environments. The C 12 is also more frequent in the mollusks from continental environments. The carbon isotopic composition in paterns from continental environments is situated betwen - 10.31 and - 4,05% and the oxygen isotopic composition is situated between - 6,95 and - 2,41%. To the marine environment patterns the carbon isotopic composition is between - 2,08 and + 2,65% and the oxigen isotopic composition is between - 2,08 and + 0,45%. Was also analysed fossil marine mollusks shells and their isotopic composition permit the formulation of hypothesis about the environment which they lived. (C.D.G.) [pt

  16. Electroreduction of oxygen on carbon-supported gold catalysts

    International Nuclear Information System (INIS)

    Erikson, Heiki; Juermann, Gea; Sarapuu, Ave; Potter, Robert J.; Tammeveski, Kaido

    2009-01-01

    The electrochemical reduction of oxygen was studied on Au/C catalysts (20 and 30 wt%) in 0.5 M H 2 SO 4 and 0.1 M KOH solutions using the rotating disk electrode (RDE) method. The thickness of the Au/C-Nafion layers was varied between 1.5 and 10 μm. The specific activity of Au was independent of catalyst loading in both solutions, indicating that the transport of reactants through the catalyst layer does not limit the process of oxygen reduction under these conditions. The mass activity of 20 wt% Au/C catalysts was higher due to smaller particle size. The number of electrons involved in the reaction and the Tafel slopes were found; the values of these parameters are similar to that of bulk polycrystalline gold and indicate that the mechanism of O 2 reduction is not affected by carbon support or the catalyst configuration.

  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. Convective mixing length and the galactic carbon to oxygen ratio

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, A; Peimbert, M [Universidad Nacional Autonoma de Mexico, Mexico City. Inst. de Astronomia

    1981-01-01

    We have studied chemical evolution models, assuming instantaneous recycling, and considering: a) the effects of mass loss both in massive stars and in intermediate mass stars, and b) the initial mass function of the solar neighbourhood (Serrano 1978). From these models we have derived the yields of carbon and oxygen. It is concluded that the condition C/O approximately 0.58 in the solar neighbourhood can only be satisfied if, during advanced stages of stellar evolution of intermediate mass stars, the ratio of the convective mixing length to the pressure scale height is > approximately 2.

  19. Optoacoustic measurements of human placenta and umbilical blood oxygenation

    Science.gov (United States)

    Nanovskaya, T. N.; Petrov, I. Y.; Petrov, Y.; Patrikeeva, S. L.; Ahmed, M. S.; Hankins, G. D. V.; Prough, D. S.; Esenaliev, R. O.

    2016-03-01

    Adequate oxygenation is essential for normal embryogenesis and fetal growth. Perturbations in the intrauterine oxidative environment during pregnancy are associated with several pathophysiological disorders such as pregnancy loss, preeclampsia, and intrauterine growth restriction. We proposed to use optoacoustic technology for monitoring placental and fetal umbilical blood oxygenation. In this work, we studied optoacoustic monitoring of oxygenation in placenta and umbilical cord blood ex vivo using technique of placenta perfusion. We used a medical grade, nearinfrared, tunable, optoacoustic system developed and built for oxygenation monitoring in blood vessels and in tissues. First, we calibrated the system for cord blood oxygenation measurements by using a CO-Oximeter (gold standard). Then we performed validation in cord blood circulating through the catheters localized on the fetal side of an isolated placental lobule. Finally, the oxygenation measurements were performed in the perfused placental tissue. To increase or decrease blood oxygenation, we used infusion of a gas mixture of 95% O2 + 5% CO2 and 95% N2 + 5% CO2, respectively. In placental tissue, up to four cycles of changes in oxygenation were performed. The optoacoustically measured oxygenation in circulating cord blood and in placental lobule closely correlated with the actual oxygenation data measured by CO-Oximeter. We plan to further test the placental and cord blood oxygenation monitoring with optoacoustics in animal and clinical studies.

  20. 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...

  1. CARBON AND OXYGEN ISOTOPIC RATIOS FOR NEARBY MIRAS

    Energy Technology Data Exchange (ETDEWEB)

    Hinkle, Kenneth H. [National Optical Astronomy Observatory P.O. Box 26732, Tucson, AZ 85726 (United States); Lebzelter, Thomas [Department of Astrophysics, University of Vienna Türkenschanzstrasse 17, A-1180 Vienna (Austria); Straniero, Oscar, E-mail: khinkle@noao.edu, E-mail: thomas.lebzelter@univie.ac.at, E-mail: straniero@oa-teramo.inaf.it [INAF, Osservatorio Astronomico di Collurania I-64100 Teramo (Italy)

    2016-07-01

    Carbon and oxygen isotopic ratios are reported for a sample of 46 Mira and SRa-type variable asymptotic giant branch (AGB) stars. Vibration–rotation first and second-overtone CO lines in 1.5–2.5 μ m spectra were measured to derive isotopic ratios for {sup 12}C/{sup 13}C, {sup 16}O/{sup 17}O, and {sup 16}O/{sup 18}O. Comparisons with previous measurements for individual stars and with various samples of evolved stars, as available in the extant literature, are discussed. Models for solar composition AGB stars of different initial masses are used to interpret our results. We find that the majority of M-stars have main sequence masses ≤2 M {sub ⊙} and have not experienced sizable third dredge-up (TDU) episodes. The progenitors of the four S-type stars in our sample are slightly more massive. Of the six C-stars in the sample three have clear evidence relating their origin to the occurrence of TDU. Comparisons with O-rich presolar grains from AGB stars that lived before the formation of the solar system reveal variations in the interstellar medium chemical composition. The present generation of low-mass AGB stars, as represented by our sample of long period variables (LPVs), shows a large spread of {sup 16}O/{sup 17}O ratios, similar to that of group 1 presolar grains and in agreement with theoretical expectations for the composition of mass 1.2–2 M {sub ⊙} stars after the first dredge-up. In contrast, the {sup 16}O/{sup 18}O ratios of present-day LPVs are definitely smaller than those of group 1 grains. This is most probably a consequence of the the decrease with time of the {sup 16}O/{sup 18}O ratio in the interstellar medium due to the chemical evolution of the Milky Way. One star in our sample has an O composition similar to that of group 2 presolar grains originating in an AGB star undergoing extra-mixing. This may indicate that the extra-mixing process is hampered at high metallicity, or, equivalently, favored at low metallicity. Similarly to O

  2. Effect of different chemical modification of carbon nanotubes for the oxygen reduction reaction in alkaline media

    International Nuclear Information System (INIS)

    Dumitru, Anca; Mamlouk, M.; Scott, K.

    2014-01-01

    The electrochemical reduction of oxygen on chemically modified multi-walled carbon nanotubes (CNTs) electrodes in 1 M KOH solution has been studied using the rotating ring disc electrode (RDE). The surface modification of CNTs has been estimated by XPS and Raman spectroscopy. The effect of different oxygen functionalities on the surface of carbon nanotube for the oxygen reduction reaction (ORR) is considered in terms of the number of electrons (n) involved. Electrochemical studies indicate that in the case of the modification of CNTs with citric acid and diazonium salts the n values were close to two in the measured potential range, and the electrochemical reduction is limited to the production of peroxide as the final product. In the case of the modification of carbon nanotubes with peroxymonosulphuric acid, in the measured potential range, the n value is close to 4 indicating the four-electron pathway for the ORR. By correlating ORR measurements with the XPS analysis, we propose that the increase in electrocatalytic activity towards the ORR, for CNT can be attributed to the increase in C-O groups on the surface of CNTs after modification with peroxymonosulphuric acid

  3. Hydrogen, carbon and oxygen determination in proxy material samples using a LaBr3:Ce detector

    International Nuclear Information System (INIS)

    Naqvi, A.A.; Al-Matouq, Faris A.; Khiari, F.Z.; Isab, A.A.; Raashid, M.; Khateeb-ur-Rehman

    2013-01-01

    Hydrogen, carbon and oxygen concentrations were measured in caffeine, urea, ammonium acetate and melamine bulk samples via 14 MeV neutron inelastic scattering using a LaBr 3 :Ce detector. The samples tested herein represent drugs, explosives and benign materials, respectively. Despite its intrinsic activity, the LaBr 3 :Ce detector performed well in detecting the hydrogen, carbon and oxygen elements. Because 5.1 MeV nitrogen gamma rays interfere with silicon and calcium prompt gamma rays from the room background, the nitrogen peak was not detected in the samples. An excellent agreement was observed between the experimental and theoretical yields of 2.22, 4.43 and 6.13 MeV gamma rays from the analyzed samples as a function of H, C and O concentrations, respectively. Within statistical errors, the minimum detectable concentration (MDC) of hydrogen, carbon and oxygen elements in the tested materials were consistent with previously reported MDC values for these elements measured in hydrocarbon samples. - Highlights: • Hydrogen, carbon and oxygen concentration measurement in bulk samples using 14 MeV neutrons induced prompt gamma rays. • Prompt gamma analysis of narcotics and explosive proxy materials e.g. ammonium acetate, caffeine, urea and melamine Bulk samples. • Prompt gamma detection using large cylindrical 76×76 mm 2 (diameter x height ) LaBr 3 :Ce detector. • Carbon/oxygen elemental ratio measurement from explosive and narcotics proxy material samples

  4. Oxygen Recovery via Carbon Dioxide Electrolysis with Microtubular Solid Oxide Cells

    Data.gov (United States)

    National Aeronautics and Space Administration — Carbon dioxide reduction is considered a major shortcoming for the current Atmosphere Revitalization System. Novel technologies are desired so that the oxygen...

  5. In situ measurements of oxygen dynamics in unsaturated archaeological deposits

    DEFF Research Database (Denmark)

    Matthiesen, Henning; Hollesen, Jørgen; Dunlop, Rory

    2015-01-01

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

  6. Oxygen-assisted multipass cutting of carbon fiber reinforced plastics with ultra-short laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Kononenko, T. V.; Komlenok, M. S.; Konov, V. I. [Natural Sciences Center, General Physics Institute, Vavilov str. 38, 119991 Moscow (Russian Federation); National Research Nuclear University, “MEPhI,” Kashirskoye shosse 31, 115409 Moscow (Russian Federation); Freitag, C. [Universität Stuttgart, Institut für Strahlwerkzeuge (IFSW), Pfaffenwaldring 43, 70569 Stuttgart (Germany); GSaME Graduate School of Excellence Advanced Manufacturing Engineering, Nobelstrasse 12, 70569 Stuttgart (Germany); Onuseit, V.; Weber, R.; Graf, T. [Universität Stuttgart, Institut für Strahlwerkzeuge (IFSW), Pfaffenwaldring 43, 70569 Stuttgart (Germany)

    2014-03-14

    Deep multipass cutting of bidirectional and unidirectional carbon fiber reinforced plastics (CFRP) with picosecond laser pulses was investigated in different static atmospheres as well as with the assistance of an oxygen or nitrogen gas flow. The ablation rate was determined as a function of the kerf depth and the resulting heat affected zone was measured. An assisting oxygen gas flow is found to significantly increase the cutting productivity, but only in deep kerfs where the diminished evaporative ablation due to the reduced laser fluence reaching the bottom of the kerf does not dominate the contribution of reactive etching anymore. Oxygen-supported cutting was shown to also solve the problem that occurs when cutting the CFRP parallel to the fiber orientation where a strong deformation and widening of the kerf, which temporarily slows down the process speed, is revealed to be typical for processing in standard air atmospheres.

  7. Oxygen-assisted multipass cutting of carbon fiber reinforced plastics with ultra-short laser pulses

    International Nuclear Information System (INIS)

    Kononenko, T. V.; Komlenok, M. S.; Konov, V. I.; Freitag, C.; Onuseit, V.; Weber, R.; Graf, T.

    2014-01-01

    Deep multipass cutting of bidirectional and unidirectional carbon fiber reinforced plastics (CFRP) with picosecond laser pulses was investigated in different static atmospheres as well as with the assistance of an oxygen or nitrogen gas flow. The ablation rate was determined as a function of the kerf depth and the resulting heat affected zone was measured. An assisting oxygen gas flow is found to significantly increase the cutting productivity, but only in deep kerfs where the diminished evaporative ablation due to the reduced laser fluence reaching the bottom of the kerf does not dominate the contribution of reactive etching anymore. Oxygen-supported cutting was shown to also solve the problem that occurs when cutting the CFRP parallel to the fiber orientation where a strong deformation and widening of the kerf, which temporarily slows down the process speed, is revealed to be typical for processing in standard air atmospheres

  8. Experimental study of negative corona discharge in pure carbon dioxide and its mixtures with oxygen

    International Nuclear Information System (INIS)

    Mikoviny, T; Kocan, M; Matejcik, S; Mason, N J; Skalny, J D

    2004-01-01

    The products of a negative corona discharge in both pure CO 2 and mixtures of CO 2 + O 2 have been studied using a coaxial cylindrical electrode geometry with particular emphasis on the production of ozone. The discharge current in pure CO 2 was found to be highly sensitive to the presence of trace concentrations of molecular oxygen and to changes in the flow speed through the discharge. The effect of dissociative electron attachment to ozone on the discharge current was studied by measurements of ozone and CO production. The ozone concentration increases monotonically with increasing content of oxygen in the mixture with carbon dioxide, whereas the CO concentration exhibits a flat maximum for oxygen concentrations of around 4%. A simple kinetic model of the dominant chemical processes is described and compared with the experimental results

  9. Action of carbon monoxide on the affinity of hemoglobin for oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Vanuxem, D.; Weiller, P.J.; Guillot, C.; Grimaud, C.

    1982-01-01

    The authors have studied the action of carbon monoxide on the affinity of hemoglobin for oxygen by measuring P50 in whole blood and in stripped hemoglobin before and after exposition of blood samples from heavy smokers and polycythemic patients with high levels of HbCO to hyperbaric oxygen (2.2 ata). The concentration of 2,3-diphosphoglycerate was normal although P50 was significantly lowered, not only in whole blood but also in stripped hemoglobin. Hyperbaric oxygen normalized P50 by removing CO radicals from stripped hemoglobin. This may indicate that CO radicals exert a direct action on the hemoglobin molecule, at least at the HbCO levels studied in this work.

  10. Cement Pastes and Mortars Containing Nitrogen-Doped and Oxygen-Functionalized Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Mauricio Martínez-Alanis

    2016-01-01

    Full Text Available Cement pastes and mortars based on ordinary Portland cement containing nitrogen-doped multiwalled carbon nanotubes (MWCNT-Nx or oxygen-functionalized multiwalled carbon nanotubes (MWCNT-Ox are investigated. To incorporate MWCNTs into the cementitious matrix, the as-produced carpets are dispersed over periods of 1 and 2 hours in distilled water at pH levels of 1 and 7. The cement pastes are prepared by adding 0.1 wt% of MWCNTs to cement powder, followed by characterization with SEM and X-ray diffraction (XRD at an early age (first hours of hydration. The mortars are mechanically characterized during the hydration process for a period of 28 days. SEM characterization of cement pastes revealed that the carbon nanotubes are well incorporated in the cementitious matrix, with the hydrated cement grains interconnected by long carbon nanotubes. XRD characterizations demonstrated that, during the hydration of cement pastes, different peaks emerged that were associated with ettringite, hydrated calcium silicate, and calcium hydroxide, among other structures. Results of the compressive strength measurements for mortars simultaneously mixed with MWCNT-Nx and MWCNT-Ox reached an increment of approximately 30% in compressive strength. In addition, density functional theory calculations were performed in nitrogen-doped and oxygen-functionalized carbon nanotubes interacting with a cement grain.

  11. Emissions & Measurements - Black Carbon | Science ...

    Science.gov (United States)

    Emissions and Measurement (EM) research activities performed within the National Risk Management Research Lab NRMRL) of EPA's Office of Research and Development (ORD) support measurement and laboratory analysis approaches to accurately characterize source emissions, and near source concentrations of air pollutants. They also support integrated Agency research programs (e.g., source to health outcomes) and the development of databases and inventories that assist Federal, state, and local air quality managers and industry implement and comply with air pollution standards. EM research underway in NRMRL supports the Agency's efforts to accurately characterize, analyze, measure and manage sources of air pollution. This pamphlet focuses on the EM research that NRMRL researchers conduct related to black carbon (BC). Black Carbon is a pollutant of concern to EPA due to its potential impact on human health and climate change. There are extensive uncertainties in emissions of BC from stationary and mobile sources. Emissions and Measurement (EM) research activities performed within the National Risk Management Research Lab NRMRL) of EPA's Office of Research and Development (ORD)

  12. Prediction of saturation using the carbon/oxygen log

    Energy Technology Data Exchange (ETDEWEB)

    Horner, S.C.; Sanyal, S.K.

    1984-09-01

    This project investigates the nature of Dresser-Atlas Carbon/Oxygen Log gamma ray spectra. It presents an attempt to improve the signal-to-noise ratio of the C/O and Si/Ca parameters used by Dresser-Atlas to determine oil saturation. Two techniques were developed to subtract the Compton background from the spectral data. Neither technique significantly improves the accuracy of the cased-hole prediction of oil saturation. However, it has been shown that it is possible to develop a satisfactory correlation for oil saturation on a well-by-well basis. This correlation can then be used to generate oil-in-place from the C/O and Si/Ca ratios. 17 references.

  13. Carbon substituting for oxygen in silicates: A novel mechanism for carbon incorporation in the deep Earth

    Science.gov (United States)

    Armentrout, M. M.; Tavakoli, A.; Ionescu, E.; Mera, G.; Riedel, R.; Navrotsky, A.

    2013-12-01

    Traditionally, carbon in the deep Earth has been thought of in terms of either carbonate at high oxygen fugacities or graphite or diamond under more reducing conditions. However, material science studies of amorphous Si-O-C polymer derived ceramics have demonstrated that carbon can be accommodated as an anion substituting for oxygen in mixed silica tetrahedra. Furthermore these structures are energetically favorable relative to a mixture of crystalline silica, silicon carbide, and graphite by ten or more kJ/g.atom. Thermodynamic stability suggests that these nano-structured composites are a potentially important storage mechanism for carbon under moderately reducing conditions. Here we expand the scope of the previous work by examining the compositional effect of geologically relevant cations (calcium and magnesium) on the thermodynamic stability, nanostructure, and ability to accommodate carbon of these composites. Silicon oxy-carbides doped with magnesium, magnesium and calcium or undoped resisted crystallization at 1100 C under inert atmosphere. 29Si NMR of the samples shows a similar distribution of silicon between end-member and mixed sites (Table 1). Results are presented from studies utilizing NMR, high temperature solution calorimetry, and microprobe. Table 1. Percentages of Si species in each material as determined by 29Si NMR.

  14. Analytical Method for Carbon and Oxygen Isotope of Small Carbonate Samples with the GasBench Ⅱ-IRMS Device

    Directory of Open Access Journals (Sweden)

    LIANG Cui-cui

    2015-01-01

    Full Text Available An analytical method for measuring carbon and oxygen isotopic compositions of trace amount carbonate (>15 μg was established by Delta V Advantage isotope Ratio MS coupled with GasBench Ⅱ. Different trace amount (5-50 μg carbonate standard samples (IAEA-CO-1 were measured by GasBench Ⅱ with 12 mL and 3.7 mL vials. When the weight of samples was less than 40 μg and it was acidified in 12 mL vials, most standard deviations of the δ13C and δ18O were more than 0.1‰, which couldn’t satisfied high-precision measurements. When the weight of samples was greater than 15 μg and it was acidified in 3.7 mL vials, standard deviations for the δ13C and δ18O were 0.01‰-0.07‰ and 0.01‰-0.08‰ respectively, which satisfied high-precision measurements. Therefore, small 3.7 mL vials were used to increase the concentration of carbon dioxide in headspace, carbonate samples even less as 15 μg can be analyzed routinely by a GasBench Ⅱ continuous-flow IRMS. Meanwhile, the linear relationship between sample’s weight and peak’s area was strong (R2>0.993 2 and it can be used to determine the carbon content of carbonate samples.

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

    DEFF Research Database (Denmark)

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

    2004-01-01

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

  16. 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

  17. HERSCHEL MEASUREMENTS OF MOLECULAR OXYGEN IN ORION

    International Nuclear Information System (INIS)

    Goldsmith, Paul F.; Chen, Jo-Hsin; Li Di; Liseau, Rene; Black, John H.; Bell, Tom A.; Hollenbach, David; Kaufman, Michael J.; Lis, Dariusz C.; Melnick, Gary; Neufeld, David; Pagani, Laurent; Encrenaz, Pierre; Snell, Ronald; Benz, Arnold O.; Bruderer, Simon; Bergin, Edwin; Caselli, Paola; Caux, Emmanuel; Falgarone, Edith

    2011-01-01

    We report observations of three rotational transitions of molecular oxygen (O 2 ) in emission from the H 2 Peak 1 position of vibrationally excited molecular hydrogen in Orion. We observed the 487 GHz, 774 GHz, and 1121 GHz lines using the Heterodyne Instrument for the Far Infrared on the Herschel Space Observatory, having velocities of 11 km s -1 to 12 km s -1 and widths of 3 km s -1 . The beam-averaged column density is N(O 2 ) = 6.5 x 10 16 cm -2 , and assuming that the source has an equal beam-filling factor for all transitions (beam widths 44, 28, and 19''), the relative line intensities imply a kinetic temperature between 65 K and 120 K. The fractional abundance of O 2 relative to H 2 is (0.3-7.3) x 10 -6 . The unusual velocity suggests an association with a ∼5'' diameter source, denoted Peak A, the Western Clump, or MF4. The mass of this source is ∼10 M sun and the dust temperature is ≥150 K. Our preferred explanation of the enhanced O 2 abundance is that dust grains in this region are sufficiently warm (T ≥ 100 K) to desorb water ice and thus keep a significant fraction of elemental oxygen in the gas phase, with a significant fraction as O 2 . For this small source, the line ratios require a temperature ≥180 K. The inferred O 2 column density ≅5 x 10 18 cm -2 can be produced in Peak A, having N(H 2 ) ≅ 4 x 10 24 cm -2 . An alternative mechanism is a low-velocity (10-15 km s -1 ) C-shock, which can produce N(O 2 ) up to 10 17 cm -2 .

  18. Water relations link carbon and oxygen isotope discrimination to phloem sap sugar concentration in eucalyptus globulus

    International Nuclear Information System (INIS)

    Cernusak, L.A.; Farquhar, G.D.; Arthur, D.J; Pate, J.S.

    2002-01-01

    Full text: The carbon isotope ratio of phloem sap sugars has been previously observed to correlate strongly with the phloem sap sugar concentration in Eucalyptus globulus. We hypothesized that the correspondence between these two parameters results from co-linearity in their responses to variation in plant water potential. Carbon isotope discrimination is expected to decrease with decreasing plant water potential due to the influence of stomatal conductance on the ratio of intercellular to ambient CO 2 , concentrations (c 1 /c a ). Conversely, we expected the phloem sap sugar concentration to increase with decreasing plant water potential, thereby maintaining positive turgor pressure within the sieve tubes. The study comprised 40 individual Eucalyptus globulus trees growing in three plantations situated on opposing ends of a rainfall gradient in southwestern Australia. A strong correlation was observed between the carbon isotope ratio in phloem sap sugars and phloem sap sugar concentration. Carbon isotope discrimination correlated positively with shoot water potential, whereas phloem sap sugar concentration correlated negatively with shoot water potential. The relationship between carbon isotope discrimination measured in phloem sap sugars collected from the stem and c 1 /c a measured instantaneously on subtending leaves was close to that theoretically predicted. Accordingly, a strong, negative relationship was observed between instantaneous c 1 /c a and the phloem sap sugar concentration. Oxygen isotope discrimination in phloem sap sugars also correlated strongly with phloem sap sugar concentration. A theoretical model suggested that the observed variation in stomatal conductance was sufficient to account for the variation observed in oxygen isotope discrimination across the study. Results strongly support the contention that water relations form a mechanistic link between phloem sap sugar concentration and both instantaneous and integrated measures of the

  19. Single electron detachment of carbon group and oxygen group elements incident on helium

    International Nuclear Information System (INIS)

    Huang Yongyi; Li Guangwu; Gao Yinghui; Yang Enbo; Gao Mei; Lu Fuquan; Zhang Xuemei

    2006-01-01

    The absolute single electron detachment (SED) cross sections of carbon group elements C - , Si - , Ge - in the energy range of 0.05-0.29 a.u. (5 keV-30 keV) and oxygen group elements O - and S - 0.08-0.27 a.u. (5 keV-30 keV), incident on helium are measured with growth rate method. In our energy region, the SED cross sections of C - , Si - , S - and Ge - increase with the projectiles velocity, at the same time, O - cross sections reach a conspicuous maximum at 0.18 a.u. Some abnormal behavior occurs in measurement of SED cross sections for the oxygen group collision with helium. Our results have been compared with a previous work

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

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  1. Ion measurements in premixed methane-oxygen flames

    KAUST Repository

    Alquaity, Awad; Hourani, Nadim; Chahine, May; Selim, Hatem; Sarathy, Mani; Farooq, Aamir

    2014-01-01

    Mass Spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane-oxygen-argon burner-stabilized flames. Lean, stoichiometric and rich flames at atmospheric pressure are used to study the dependence of ion chemistry

  2. Single-cell measurement of red blood cell oxygen affinity

    OpenAIRE

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

    2015-01-01

    Oxygen is transported throughout the body by hemoglobin in red blood cells. While the oxygen affinity of blood is well understood and is routinely assessed in patients by pulse oximetry, variability at the single-cell level has not been previously measured. In contrast, single-cell measurements of red blood cell volume and hemoglobin concentration are taken millions of times per day by clinical hematology analyzers and are important factors in determining the health of the hematologic system....

  3. Synthesis of 2D Nitrogen-Doped Mesoporous Carbon Catalyst for Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Zhipeng Yu

    2017-02-01

    Full Text Available 2D nitrogen-doped mesoporous carbon (NMC is synthesized by using a mesoporous silica film as hard template, which is then investigated as a non-precious metal catalyst for the oxygen reduction reaction (ORR. The effect of the synthesis conditions on the silica template and carbon is extensively investigated. In this work, we employ dual templates—viz. graphene oxide and triblock copolymer F127—to control the textural features of a 2D silica film. The silica is then used as a template to direct the synthesis of a 2D nitrogen-doped mesoporous carbon. The resultant nitrogen-doped mesoporous carbon is characterized by transmission electron microscopy (TEM, nitrogen ad/desorption isotherms, X-ray photoelectron spectroscopy (XPS, cyclic voltammetry (CV, and rotating disk electrode measurements (RDE. The electrochemical test reveals that the obtained 2D-film carbon catalyst yields a highly electrochemically active surface area and superior electrocatalytic activity for the ORR compared to the 3D-particle. The superior activity can be firstly attributed to the difference in the specific surface area of the two catalysts. More importantly, the 2D-film morphology makes more active sites accessible to the reactive species, resulting in a much higher utilization efficiency and consequently better activity. Finally, it is noted that all the carbon catalysts exhibit a higher ORR activity than a commercial Pt catalyst, and are promising for use in fuel cells.

  4. Regional myocardial oxygen consumption estimated by carbon-11 acetate and positron emission tomography before and after repetitive ischemia

    DEFF Research Database (Denmark)

    Kofoed, K F; Hansen, P R; Holm, S

    2000-01-01

    alternating with 5 minutes of reperfusion. Before and after repetitive coronary occlusions, oxygen 15 water/oxygen 15 carbon monoxide (blood flow), and 11C-acetate (oxygen consumption) PET imaging were performed. Left ventricular regional systolic wall thickening was measured with sonomicrometry. Forty......BACKGROUND: Preserved myocardial oxygen consumption estimated by carbon 11-acetate and positron emission tomography (PET) in myocardial regions with chronic but reversibly depressed contractile function in patients with ischemic heart disease have been suggested to be caused by repeated short......-five minutes after the ischemic episodes, systolic ventricular wall thickening was decreased by 90%, whereas myocardial blood flow was reduced by 21% compared with baseline values (P consumption was unaltered compared with the baseline level...

  5. [Effect of oxygen tubing connection site on percutaneous oxygen partial pressure and percutaneous carbon dioxide partial pressure in patients with chronic obstructive pulmonary disease during noninvasive positive pressure ventilation].

    Science.gov (United States)

    Mi, S; Zhang, L M

    2017-04-12

    Objective: We evaluated the effects of administering oxygen through nasal catheters inside the mask or through the mask on percutaneous oxygen partial pressure (PcO(2))and percutaneous carbon dioxide partial pressure (PcCO(2)) during noninvasive positive pressure ventilation (NPPV) to find a better way of administering oxygen, which could increase PcO(2) by increasing the inspired oxygen concentration. Methods: Ten healthy volunteers and 9 patients with chronic obstructive pulmonary disease complicated by type Ⅱ respiratory failure were included in this study. Oxygen was administered through a nasal catheter inside the mask or through the mask (oxygen flow was 3 and 5 L/min) during NPPV. PcO(2) and PcCO(2) were measured to evaluate the effects of administering oxygen through a nasal catheter inside the mask or through the mask, indirectly reflecting the effects of administering oxygen through nasal catheter inside the mask or through the mask on inspired oxygen concentration. Results: Compared to administering oxygen through the mask during NPPV, elevated PcO(2) was measured in administering oxygen through the nasal catheter inside the mask, and the differences were statistically significant ( P 0.05). Conclusion: Administering oxygen through a nasal catheter inside the mask during NPPV increased PcO(2) by increasing the inspired oxygen concentration but did not increase PcCO(2). This method of administering oxygen could conserve oxygen and be suitable for family NPPV. Our results also provided theoretical basis for the development of new masks.

  6. Low oxygen affects photophysiology and the level of expression of two-carbon metabolism genes in the seagrass Zostera muelleri.

    Science.gov (United States)

    Kim, Mikael; Brodersen, Kasper Elgetti; Szabó, Milán; Larkum, Anthony W D; Raven, John A; Ralph, Peter J; Pernice, Mathieu

    2018-05-01

    Seagrasses are a diverse group of angiosperms that evolved to live in shallow coastal waters, an environment regularly subjected to changes in oxygen, carbon dioxide and irradiance. Zostera muelleri is the dominant species in south-eastern Australia, and is critical for healthy coastal ecosystems. Despite its ecological importance, little is known about the pathways of carbon fixation in Z. muelleri and their regulation in response to environmental changes. In this study, the response of Z. muelleri exposed to control and very low oxygen conditions was investigated by using (i) oxygen microsensors combined with a custom-made flow chamber to measure changes in photosynthesis and respiration, and (ii) reverse transcription quantitative real-time PCR to measure changes in expression levels of key genes involved in C 4 metabolism. We found that very low levels of oxygen (i) altered the photophysiology of Z. muelleri, a characteristic of C 3 mechanism of carbon assimilation, and (ii) decreased the expression levels of phosphoenolpyruvate carboxylase and carbonic anhydrase. These molecular-physiological results suggest that regulation of the photophysiology of Z. muelleri might involve a close integration between the C 3 and C 4 , or other CO 2 concentrating mechanisms metabolic pathways. Overall, this study highlights that the photophysiological response of Z. muelleri to changing oxygen in water is capable of rapid acclimation and the dynamic modulation of pathways should be considered when assessing seagrass primary production.

  7. Single-cell measurement of red blood cell oxygen affinity.

    Science.gov (United States)

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

    2015-08-11

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

  8. Interactive effects of oxygen, carbon dioxide and flow on photosynthesis and respiration in the scleractinian coral Galaxea fascicularis

    NARCIS (Netherlands)

    Osinga, Ronald; Derksen-Hooijberg, Marlous; Wijgerde, Tim; Verreth, Johan A.J.

    2017-01-01

    Rates of dark respiration and net photosynthesis were measured for six replicate clonal fragments of the stony coral Galaxea fascicularis (Linnaeus 1767), which were incubated under 12 different combinations of dissolved oxygen (20%, 100% and 150% saturation), dissolved carbon dioxide (9.5 and

  9. Variability in hyperbaric oxygen treatment for acute carbon monoxide poisoning.

    Science.gov (United States)

    Byrne, Brendan T; Lu, Jenny J; Valento, Matthew; Bryant, Sean M

    2012-01-01

    In patients with acute carbon monoxide (CO) poisoning, we have noted wide clinical variability in both criteria for hyperbaric oxygen (HBO2) treatment as well as HBO2 treatment regimens. Our aim was to survey Midwest hyperbaric centers for insight into specific criteria and protocols for treating acute CO toxicity with HBO2. Hyperbaric centers were identified from the published list of the Undersea and Hyperbaric Medical Society. Ninety-three centers from nine Midwestern states were contacted via telephone. A standard script was used to minimize surveyor bias. Thirty centers that treat CO poisonings were identified. One did not participate in the study. Nineteen reported a specific level of carboxyhemoglobin (COHb) that served as an independent indication for initiation of HBO2 treatment. Four centers used the COHb level as the exclusive indication for HBO2 treatment. Ten centers relied solely on reported symptoms, while the remaining centers used a combination of symptoms plus COHb levels. There were 19 separate treatment protocols. No uniform practice for either the initiation or implementation of HBO2 therapy for CO poisoning exists among U.S. Midwest hyperbaric centers responding to a survey. We see opportunity for specific targeted educational programs as well as further study.

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

    Science.gov (United States)

    Kanner, R E; Crapo, R O

    1986-04-01

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

  11. Mechanical and Electrochemical Performance of Carbon Fiber Reinforced Polymer in Oxygen Evolution Environment

    Directory of Open Access Journals (Sweden)

    Ji-Hua Zhu

    2016-11-01

    Full Text Available Carbon fiber-reinforced polymer (CFRP is recognized as a promising anode material to prevent steel corrosion in reinforced concrete. However, the electrochemical performance of CFRP itself is unclear. This paper focuses on the understanding of electrochemical and mechanical properties of CFRP in an oxygen evolution environment by conducting accelerated polarization tests. Different amounts of current density were applied in polarization tests with various test durations, and feeding voltage and potential were measured. Afterwards, tensile tests were carried out to investigate the failure modes for the post-polarization CFRP specimens. Results show that CFRP specimens had two typical tensile-failure modes and had a stable anodic performance in an oxygen evolution environment. As such, CFRP can be potentially used as an anode material for impressed current cathodic protection (ICCP of reinforced concrete structures, besides the fact that CFRP can strengthen the structural properties of reinforced concrete.

  12. Monitoring and measurement of oxygen concentrations in liquid sodium

    International Nuclear Information System (INIS)

    Smith, D.L.

    1976-01-01

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

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

    Science.gov (United States)

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

    2017-12-01

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

  14. Preliminary results of oxygen isotope ratio measurement with a particle-gamma coincidence method

    Energy Technology Data Exchange (ETDEWEB)

    Borysiuk, Maciek, E-mail: maciek.borysiuk@pixe.lth.se; Kristiansson, Per; Ros, Linus; Abdel, Nassem S.; Elfman, Mikael; Nilsson, Charlotta; Pallon, Jan

    2015-04-01

    The possibility to study variations in the oxygen isotopic ratio with photon tagged nuclear reaction analysis (pNRA) is evaluated in the current work. The experiment described in the article was performed at Lund Ion Beam Analysis Facility (LIBAF) with a 2 MeV deuteron beam. Isotopic fractionation of light elements such as carbon, oxygen and nitrogen is the basis of many analytical tools in hydrology, geology, paleobiology and paleogeology. IBA methods provide one possible tool for measurement of isotopic content. During this experimental run we focused on measurement of the oxygen isotopic ratio. The measurement of stable isotopes of oxygen has a number of applications; the particular one driving the current investigation belongs to the field of astrogeology and specifically evaluation of fossil extraterrestrial material. There are three stable isotopes of oxygen: {sup 16}O, {sup 17}O and {sup 18}O. We procured samples highly enriched with all three isotopes. Isotopes {sup 16}O and {sup 18}O were easily detected in the enriched samples, but no significant signal from {sup 17}O was detected in the same samples. The measured yield was too low to detect {sup 18}O in a sample with natural abundances of oxygen isotopes, at least in the current experimental setup, but the spectral line from the reaction with {sup 16}O was clearly visible.

  15. Oxygen measurement by multimode diode lasers employing gas correlation spectroscopy.

    Science.gov (United States)

    Lou, Xiutao; Somesfalean, Gabriel; Chen, Bin; Zhang, Zhiguo

    2009-02-10

    Multimode diode laser (MDL)-based correlation spectroscopy (COSPEC) was used to measure oxygen in ambient air, thereby employing a diode laser (DL) having an emission spectrum that overlaps the oxygen absorption lines of the A band. A sensitivity of 700 ppm m was achieved with good accuracy (2%) and linearity (R(2)=0.999). For comparison, measurements of ambient oxygen were also performed by tunable DL absorption spectroscopy (TDLAS) technique employing a vertical cavity surface emitting laser. We demonstrate that, despite slightly degraded sensitivity, the MDL-based COSPEC-based oxygen sensor has the advantages of high stability, low cost, ease-of-use, and relaxed requirements in component selection and instrument buildup compared with the TDLAS-based instrument.

  16. Measurement of oxygen thermomigration in a hypostoichiometric mixed oxide

    International Nuclear Information System (INIS)

    Norris, D.I.R.; Coleman, S.C.; Kay, P.

    1978-08-01

    A method of determining oxygen to metal ratios in hypostoichiometric (U, Ce)Osub(2-x) by means of lattice parameter measurement and its application to thermomigration experiments is described. The technique is shown to compare favourably with other methods when a simple structure prevails. It is found that oxygen redistributes down an imposed temperature gradient, confirming theoretical predictions, and that the measured Arrhenius slope decreases as the cerium valency decreases. This effect is more marked than in (U, Pu)Osub(2-x). The results are attributable to solid state transport of oxygen vacancies and suggest that immobile complexes incorporating some oxygen deficiency are more easily formed in (U, Ce)Osub(2-x) than in (U, Pu)Osub(2-x). (author)

  17. Measuring carbon in shrubs. Chapter 5

    Science.gov (United States)

    David C. Chojnacky; Mikaila Milton

    2008-01-01

    Although shrubs are a small component of the overall carbon budget, shrub lands and shrub cover within forested lands warrant monitoring with consistent procedures to account for carbon in shrubs and to track carbon accumulation as communities change from shrubs to trees and vice versa. Many different procedures have been used to sample and measure shrubs (Bonham 1989...

  18. Electrocatalysis of oxygen reduction on nitrogen-containing multi-walled carbon nanotube modified glassy carbon electrodes

    International Nuclear Information System (INIS)

    Vikkisk, Merilin; Kruusenberg, Ivar; Joost, Urmas; Shulga, Eugene; Tammeveski, Kaido

    2013-01-01

    Highlights: ► Pyrolysis in the presence of urea was used for nitrogen doping of carbon nanotubes. ► N-doped carbon nanotubes were used as catalysts for the oxygen reduction reaction. ► N-doped carbon material showed a high catalytic activity for ORR in alkaline media. ► N-containing CNT material is an attractive cathode catalyst for alkaline membrane fuel cells. - Abstract: The electrochemical reduction of oxygen was studied on nitrogen-doped multi-walled carbon nanotube (NCNT) modified glassy carbon (GC) electrodes employing the rotating disk electrode (RDE) method. Nitrogen doping was achieved by simple pyrolysis of the carbon nanotube material in the presence of urea. The surface morphology and composition of the NCNT samples were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The SEM images revealed a rather uniform distribution of NCNTs on the GC electrode substrate. The XPS analysis showed a successful doping of carbon nanotubes with nitrogen species. The RDE results revealed that in alkaline solution the N-doped nanotube materials showed a remarkable electrocatalytic activity towards oxygen reduction. At low overpotentials the reduction of oxygen followed a two-electron pathway on undoped carbon nanotube modified GC electrodes, whereas on NCNT/GC electrodes a four-electron pathway of O 2 reduction predominated. The results obtained are significant for the development of nitrogen-doped carbon-based cathodes for alkaline membrane fuel cells.

  19. Diffuse reflectance spectroscopy for the measurement of tissue oxygen saturation

    International Nuclear Information System (INIS)

    Sircan-Kucuksayan, A; Canpolat, M; Uyuklu, M

    2015-01-01

    Tissue oxygen saturation (StO 2 ) is a useful parameter for medical applications. A spectroscopic method has been developed to detect pathologic tissues, due to a lack of normal blood circulation, by measuring StO 2 . In this study, human blood samples with different levels of oxygen saturation have been prepared and spectra were acquired using an optical fiber probe to investigate the correlation between the oxygen saturation levels and the spectra. A linear correlation between the oxygen saturation and ratio of the intensities (760 nm to 790 nm) of the spectra acquired from blood samples has been found. In a validation study, oxygen saturations of the blood samples were estimated from the spectroscopic measurements with an error of 2.9%. It has also been shown that the linear dependence between the ratio and the oxygen saturation of the blood samples was valid for the blood samples with different hematocrits. Spectra were acquired from the forearms of 30 healthy volunteers to estimate StO 2 prior to, at the beginning of, after 2 min, and at the release of total vascular occlusion. The average StO 2 of a forearm before and after the two minutes occlusion was significantly different. The results suggested that optical reflectance spectroscopy is a sensitive method to estimate the StO 2 levels of human tissue. The technique developed to measure StO 2 has potential to detect ischemia in real time. (paper)

  20. Temperature, salinity, nutrients, freons, oxygen, currents (ADCP), underway and other measurements collected in the Gulf of Mexico and Atlantic as part of the Gulf of Mexico and East Coast Carbon Cruise (GOMECC) 2007 (NODC Accession 0066603)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — GOMECC Gulf of Mexico and East Coast Carbon Cruise(RB 07-05). North American Carbon Program (NACP) Gulf of Mexico and East Coast Carbon (GOMECC) Cruise on board NOAA...

  1. Characterization of hydrogen, nitrogen, oxygen, carbon and sulfur in nuclear fuel (UO2) and cladding nuclear rod materials

    International Nuclear Information System (INIS)

    Crewe, Maria Teresa I.; Lopes, Paula Corain; Moura, Sergio C.; Sampaio, Jessica A.G.; Bustillos, Oscar V.

    2011-01-01

    The importance of Hydrogen, Nitrogen, Oxygen, Carbon and Sulfur gases analysis in nuclear fuels such as UO 2 , U 3 O 8 , U 3 Si 2 and in the fuel cladding such as Zircaloy, is a well known as a quality control in nuclear industry. In UO 2 pellets, the Hydrogen molecule fragilizes the metal lattice causing the material cracking. In Zircaloy material the H2 molecules cause the boiling of the cladding. Other gases like Nitrogen, Oxygen, Carbon and Sulfur affect in the lattice structure change. In this way these chemical compounds have to be measure within specify parameters, these measurement are part of the quality control of the nuclear industry. The analytical procedure has to be well established by a convention of the quality assurance. Therefore, the Oxygen, Carbon, Sulfur and Hydrogen are measured by infrared absorption (IR) and the nitrogen will be measured by thermal conductivity (TC). The gas/metal analyzer made by LECO Co. model TCHEN-600 is Hydrogen, Oxygen and Nitrogen analyzer in a variety of metals, refractory and other inorganic materials, using the principle of fusion by inert gas, infrared and thermo-coupled detector. The Carbon and Sulfur compounds are measure by LECO Co. model CS-400. A sample is first weighed and placed in a high purity graphite crucible and is casted on a stream of helium gas, enough to release the oxygen, nitrogen and hydrogen. During the fusion, the oxygen present in the sample combines with the carbon crucible to form carbon monoxide. Then, the nitrogen present in the sample is analyzed and released as molecular nitrogen and the hydrogen is released as gas. The hydrogen gas is measured by infrared absorption, and the sample gases pass through a trap of copper oxide which converts CO to CO 2 and hydrogen into water. The gases enter the cell where infrared water content is then converted making the measurement of total hydrogen present in the sample. The Hydrogen detection limits for the nuclear fuel is 1 μg/g for the Nitrogen

  2. Carbon fiber CVD coating by carbon nanostructured for space materials protection against atomic oxygen

    Science.gov (United States)

    Pastore, Roberto; Bueno Morles, Ramon; Micheli, Davide

    2016-07-01

    , by the purpose to integrate the carbon nanostructures in the carbon fibers by means of chemical vapor deposition (CVD) method, in order to develop the basic substrate of advanced carbon-based nanocomposite for atomic oxygen protection. The nanostructures grown onto the carbon fibers can be used to create multiscale hybrid carbon nanotube/carbon fiber composites where individual carbon fibers, which are several microns in diameter, are surrounded by nanotubes. The present objective is the setting-up of the CVD parameters for a reliable growth of carbon nanostructures on carbon fiber surface; after that, the results of a preliminary characterization related to atomic oxygen effects testing by means of a ground LEO simulation facility are reported and discussed.

  3. Microscopic oxygen imaging based on fluorescein bleaching efficiency measurements

    DEFF Research Database (Denmark)

    Beutler, Martin; Heisterkamp, Ines M.; Piltz, Bastian

    2014-01-01

    by a charge-coupled-device (ccd) camera mounted on a fluorescence microscope allowed a pixelwise estimation of the ratio function in a microscopic image. Use of a microsensor and oxygen-consuming bacteria in a sample chamber enabled the calibration of the system for quantification of absolute oxygen......Photobleaching of the fluorophore fluorescein in an aqueous solution is dependent on the oxygen concentration. Therefore, the time-dependent bleaching behavior can be used to measure of dissolved oxygen concentrations. The method can be combined with epi-fluorescence microscopy. The molecular...... states of the fluorophore can be expressed by a three-state energy model. This leads to a set of differential equations which describe the photobleaching behavior of fluorescein. The numerical solution of these equations shows that in a conventional wide-field fluorescence microscope, the fluorescence...

  4. Cerebral blood oxygenation measurements in neonates with optoacoustic technique

    Science.gov (United States)

    Herrmann, Stephen; Petrov, Irene Y.; Petrov, Yuriy; Richardson, C. Joan; Fonseca, Rafael A.; Prough, Donald S.; Esenaliev, Rinat O.

    2017-03-01

    Cerebral hypoxia is a major contributor to neonatal/infant mortality and morbidity including severe neurological complications such as mental retardation, cerebral palsy, motor impairment, and epilepsy. Currently, no technology is capable of accurate monitoring of neonatal cerebral oxygenation. We proposed to use optoacoustics for this application by probing the superior sagittal sinus (SSS), a large central cerebral vein. We developed and built a multi-wavelength, optical parametric oscillator (OPO) and laser diode optoacoustic systems for measurement of SSS blood oxygenation in the reflection mode through open anterior or posterior fontanelles and in the transmission mode through the skull in the occipital area. In this paper we present results of initial tests of the laser diode system for neonatal cerebral oxygenation measurements. First, the system was tested in phantoms simulating neonatal SSS. Then, using the data obtained in the phantoms, we optimized the system's hardware and software and tested it in neonates admitted in the Neonatal Intensive Care Unit. The laser diode system was capable of detecting SSS signals in the reflection mode through the open anterior and posterior fontanelles as well as in the transmission mode through the skull with high signal-to-noise ratio. Using the signals measured at different wavelengths and algorithms developed for oxygenation measurements, the laser diode system provided real-time, continuous oxygenation monitoring with high precision at all these locations.

  5. Blood oxygen and carbon dioxide transport in man

    OpenAIRE

    McElderry, Linda A.

    1981-01-01

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

  6. 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)

  7. Identification of catalytic sites in cobalt-nitrogen-carbon materials for the oxygen reduction reaction.

    Science.gov (United States)

    Zitolo, Andrea; Ranjbar-Sahraie, Nastaran; Mineva, Tzonka; Li, Jingkun; Jia, Qingying; Stamatin, Serban; Harrington, George F; Lyth, Stephen Mathew; Krtil, Petr; Mukerjee, Sanjeev; Fonda, Emiliano; Jaouen, Frédéric

    2017-10-16

    Single-atom catalysts with full utilization of metal centers can bridge the gap between molecular and solid-state catalysis. Metal-nitrogen-carbon materials prepared via pyrolysis are promising single-atom catalysts but often also comprise metallic particles. Here, we pyrolytically synthesize a Co-N-C material only comprising atomically dispersed cobalt ions and identify with X-ray absorption spectroscopy, magnetic susceptibility measurements and density functional theory the structure and electronic state of three porphyrinic moieties, CoN 4 C 12 , CoN 3 C 10,porp and CoN 2 C 5 . The O 2 electro-reduction and operando X-ray absorption response are measured in acidic medium on Co-N-C and compared to those of a Fe-N-C catalyst prepared similarly. We show that cobalt moieties are unmodified from 0.0 to 1.0 V versus a reversible hydrogen electrode, while Fe-based moieties experience structural and electronic-state changes. On the basis of density functional theory analysis and established relationships between redox potential and O 2 -adsorption strength, we conclude that cobalt-based moieties bind O 2 too weakly for efficient O 2 reduction.Nitrogen-doped carbon materials with atomically dispersed iron or cobalt are promising for catalytic use. Here, the authors show that cobalt moieties have a higher redox potential, bind oxygen more weakly and are less active toward oxygen reduction than their iron counterpart, despite similar coordination.

  8. Self-Cleaning Boudouard Reactor for Full Oxygen Recovery from Carbon Dioxide

    Science.gov (United States)

    Coutts, Janelle; Hintze, Paul E.; Muscatello, Anthony C.; Gibson, Tracy L.; Captain, James G.; Lunn, Griffin M.; Devor, Robert W.; Bauer, Brint; Parks, Steve

    2016-01-01

    Oxygen recovery from respiratory carbon dioxide is an important aspect of human spaceflight. Methods exist to sequester the carbon dioxide, but production of oxygen needs further development. The current International Space Station Carbon Dioxide Reduction System (CRS) uses the Sabatier reaction to produce water (and ultimately breathing air). Oxygen recovery is limited to 50 because half of the hydrogen used in the Sabatier reactor is lost as methane, which is vented overboard. The Bosch reaction, which converts carbon dioxide to oxygen and solid carbon is capable of recovering all the oxygen from carbon dioxide, and is the only real alternative to the Sabatier reaction. However, the last reaction in the cycle, the Boudouard reaction, produces solid carbon and the resulting carbon buildup will eventually foul the nickel or iron catalyst, reducing reactor life and increasing consumables. To minimize this fouling and increase efficiency, a number of self-cleaning catalyst designs have been created. This paper will describe recent results evaluating one of the designs.

  9. Imaging the Oxygen-Rich Disk Toward the Silicate Carbon Star EU Andromedae

    National Research Council Canada - National Science Library

    Ohnaka, K; Boboltz, D. A

    2007-01-01

    .... We present multi-epoch, high-angular resolution observations of 22 GHz H2O masers toward the silicate carbon star EU And to probe the spatio-kinematic distribution of oxygen-rich material. Methods...

  10. Magnetic susceptibility of oxygen adsorbed on the surface of spherical and fibrous activated carbon.

    Directory of Open Access Journals (Sweden)

    Kiyoshi Kawamura

    2009-02-01

    Full Text Available The magnetic susceptibilities of oxygen adsorbed on the surface of bead-shaped activated carbon and activated carbon fibers were evaluated as a function of temperature between 4.2 K and 300 K, and found to exhibit a sharp peak at around 50 K. This implies that the adsorbed oxygen molecules form an antiferromagnetic state. The relation between the susceptibility and the adsorbed mass suggest that the thickness of the adsorbed oxygen is thin enough to consider a two-dimensional structure for bead–shaped activated carbon and carbon fibers across the fiber axis but thick enough to regard it as three-dimensional along the fiber axis. The result is discussed with reference to the study on one-dimensional oxygen array.

  11. The effect of carbon-chain oxygenation in the carbon-carbon dissociation.

    Science.gov (United States)

    Dos Santos, Lisandra Paulino; Baptista, Leonardo

    2018-06-01

    Currently, there is a trend of moving away from the use of fossil fuels to the use of biofuels. This modification changes the molecular structure of gasoline and diesel constituents, which should impact pollutant emissions and engine efficiency. An important property of automotive fuels is the resistance to autoignition. The goal of the present work is to evaluate thermochemical and kinetic parameters that govern the carbon-carbon bond dissociation and relate these parameters, in conjunction with molecular properties, to autoignition resistance. Three model reactions were investigated in the present work: dissociation of ethane, ethanol, and ethanal. All studies were conducted at the multiconfigurational level of theory, and the rate coefficients were evaluated from 300 to 2000 K. The comparison of dissociation energies and Arrhenius expressions indicates that autoignition resistance is related to the kinetic control of dissociation reactions and it is possible to relate the higher octane number of ethanol based fuels to the kinetics parameters of carbon-carbon bond fission. Graphical abstract Effect of the functional group in the Arrhenius parameters of the C-C dissociation. Arrhenius curves calculated at NEVPT2(6,6)/6-311G(2df,2pd).

  12. Vibrational Relaxation of Ground-State Oxygen Molecules With Atomic Oxygen and Carbon Dioxide

    Science.gov (United States)

    Saran, D. V.; Pejakovic, D. A.; Copeland, R. A.

    2008-12-01

    Vertical water vapor profiles are key to understanding the composition and energy budget in the mesosphere and lower thermosphere (MLT). The SABER instrument onboard NASA's TIMED satellite measures such profiles by detecting H2O(ν2) emission in the 6.8 μm region. Collisional deactivation of vibrationally excited O2, O2(X3Σ-g, υ = 1) + H2O ↔ O2(X3Σ-g, υ = 0) + H2O(ν2), is an important source of H2O(ν2). A recent study has identified two other processes involving excited O2 that control H2O(ν2) population in the MLT: (1) the vibrational-translational (V-T) relaxation of O2(X3Σ-g, υ = 1) level by atomic oxygen and (2) the V-V exchange between CO2 and excited O2 molecules [1]. Over the past few years SRI researchers have measured the atomic oxygen removal process mentioned above at room temperature [2] and 240 K [3]. These measurements have been incorporated into the models for H2O(ν2) emission [1]. Here we report laboratory studies of the collisional removal of O2(X3Σ-g, υ = 1) by O(3P) at room temperature and below, reaching temperatures relevant to mesopause and polar summer MLT (~150 K). Instead of directly detecting the O2(X3Σ-g, υ = 1) population, a technically simpler approach is used in which the υ = 1 level of the O2(a1Δg) state is monitored. A two-laser method is employed, in which the pulsed output of the first laser near 285 nm photodissociates ozone to produce atomic oxygen and O2(a1Δg, υ = 1), and the pulsed output of the second laser detects O2(a1Δg, υ = 1) via resonance-enhanced multiphoton ionization. With ground-state O2 present, owing to the rapid equilibration of the O2(X3Σ-g, υ = 1) and O2(a1Δg, υ = 1) populations via the processes O2(a1Δg, υ = 1) + O2(X3Σ-g, υ = 0) ↔ O2(a1Δg, υ = 0) + O2(X3Σ-g, υ = 1), the information on the O2(X3Σ-g, υ = 1) kinetics is extracted from the O2(a1Δg, υ = 1) temporal evolution. In addition, measurements of the removal of O2(X3Σ-g, υ = 1) by CO2 at room temperature will also

  13. Oxygen tension measurements of tumors growing in mice

    International Nuclear Information System (INIS)

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

    1999-01-01

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

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

    DEFF Research Database (Denmark)

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

    1999-01-01

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

  15. Biomedical sensor for transcutaneous oxygen measurements using thick film technology

    OpenAIRE

    Lam, Yu-Zhi (Liza)

    2003-01-01

    The measurement of the partial pressure of oxygen in arterial blood is essential for the analysis of a patient's respiratory condition. There are several commercially available methods and systems to measure this parameter transcutaneously. However, they tend to be cumbersome and costly. To overcome the disadvantages presented, a new type of sensor for transcutaneous blood gas measurement was investigated, employing thick film technology, which is an excellent technique to produce sensors in ...

  16. Use of a combined oxygen and carbon dioxide transcutaneous electrode in the estimation of gas exchange during exercise.

    OpenAIRE

    Sridhar, M K; Carter, R; Moran, F; Banham, S W

    1993-01-01

    BACKGROUND--Accurate and reliable measurement of gas exchange during exercise has traditionally involved arterial cannulation. Non-invasive devices to estimate arterial oxygen (O2) and carbon dioxide (CO2) tensions are now available. A method has been devised and evaluated for measuring gas exchange during exercise with a combined transcutaneous O2 and CO2 electrode. METHODS--Symptom limited exercise tests were carried out in 24 patients reporting effort intolerance and breathlessness. Exerci...

  17. The effect of the oxygen dissolved in the adsorption of gold in activated carbon

    International Nuclear Information System (INIS)

    Navarro, P.; Wilkomirsky, I.

    1999-01-01

    The effect of the oxygen dissolved on the adsorption of gold in a activated carbon such as these used for carbon in pulp (CIP) and carbon in leach (CIL) processes were studied. The research was oriented to dilucidate the effect of the oxygen dissolved in the gold solution on the kinetics and distribution of the gold adsorbed in the carbon under different conditions of ionic strength, pH and gold concentration. It was found that the level of the oxygen dissolved influences directly the amount of gold adsorbed on the activated carbon, being this effect more relevant for low ionic strength solutions. The pH and initial gold concentration has no effect on this behavior. (Author) 16 refs

  18. Interactive effects of oxygen, carbon dioxide and flow on photosynthesis and respiration in the scleractinian coral Galaxea fascicularis.

    Science.gov (United States)

    Osinga, Ronald; Derksen-Hooijberg, Marlous; Wijgerde, Tim; Verreth, Johan A J

    2017-06-15

    Rates of dark respiration and net photosynthesis were measured for six replicate clonal fragments of the stony coral Galaxea fascicularis (Linnaeus 1767), which were incubated under 12 different combinations of dissolved oxygen (20%, 100% and 150% saturation), dissolved carbon dioxide (9.5 and 19.1 µmol l -1 ) and water flow (1-1.6 versus 4-13 cm s -1 ) in a repeated measures design. Dark respiration was enhanced by increased flow and increased oxygen saturation in an interactive way, which relates to improved oxygen influx into the coral tissue. Oxygen saturation did not influence net photosynthesis: neither hypoxia nor hyperoxia affected net photosynthesis, irrespective of flow and pH, which suggests that hyperoxia does not induce high rates of photorespiration in this coral. Flow and pH had a synergistic effect on net photosynthesis: at high flow, a decrease in pH stimulated net photosynthesis by 14%. These results indicate that for this individual of G. fascicularis , increased uptake of carbon dioxide rather than increased efflux of oxygen explains the beneficial effect of water flow on photosynthesis. Rates of net photosynthesis measured in this study are among the highest ever recorded for scleractinian corals and confirm a strong scope for growth. © 2017. Published by The Company of Biologists Ltd.

  19. New Active Optical Technique Developed for Measuring Low-Earth-Orbit Atomic Oxygen Erosion of Polymers

    Science.gov (United States)

    Banks, Bruce A.; deGroh, Kim K.; Demko, Rikako

    2003-01-01

    uniformly thick sheet of semitransparent polymer such as Kapton H polyimide, then as atomic oxygen erodes the polymer, the short-circuit current from the photodiode will increase in an exponential manner with fluence. This nonlinear response with fluence results in a lack of sensitivity for measuring low atomic oxygen fluences. However, if one uses a variable-thickness polymer or carbon sample, which is configured as shown in the preceding figure, then a linear response can be achieved for opaque materials using a parabolic well for a circular geometry detector or a V-shaped well for a rectangular-geometry detector. Variable-thickness samples can be fabricated using many thin polymer layers. For semitransparent polymers such as Kapton H polyimide, there is an initial short-circuit current that is greater than zero. This current has a slightly nonlinear dependence on atomic oxygen fluence in comparison to opaque materials such as black Kapton as shown in the graph. For this graph figure, the total thickness of Kapton H was assumed to be 0.03 cm. The photodiode short-circuit current shown in the graph was generated on the basis of preliminary measurements-a total reflectance rho of 0.0424 and an optical absorption coefficient a of 146.5 cm(sup -1). In addition to obtaining on-orbit data, the advantage of this active erosion and erosion yield measurement technique is its simplicity and reliance upon well-characterized fluence witness materials as well as a nearly linear photodiode short-circuit current dependence upon atomic oxygen fluence. The optical technique is useful for measuring either atomic oxygen fluence or erosion, depending on the information desired. To measure the atomic oxygen erosion yield of a test material, one would need to have two photodiode sensors, one for the test material and one that uses a known erosion yield material (such as Kapton) to measure the atomic oxygen fluence.

  20. Online Measurement of Oxygen-Dependent Enzyme Reaction Kinetics

    DEFF Research Database (Denmark)

    Meissner, Murray Peter; Nordblad, Mathias; Woodley, John M

    2018-01-01

    accurate measurement of the oxygen mass balance in the gas-phase of a reactor. The method was successfully validated and demonstrated using two model reactions: firstly the oxidation of glucose by glucose oxidase and secondly the Baeyer-Villiger oxidation of macrocyclic ketones to lactones. Initial...

  1. The analysis of irradiated nuclear fuel and cladding materials, determination of carbon, hydrogen and oxygen/metal ratio

    International Nuclear Information System (INIS)

    Jones, I.G.

    1976-02-01

    Equipment has been developed for the determination of carbon, hydrogen and oxygen/metal ratio on irradiated fuels, of carbon in stainless steel cladding materials and in graphite rich deposits, and of hydrogen in zircaloy. Carbon is determined by combustion to carbon dioxide which is collected and measured manometrically, hydrogen by vacuum extraction followed by diffusion through a palladium thimble, and oxygen/metal ratio by CO/CO 2 equilibration. A single set of equipment was devised in order to minimise the time and work involved in changing to a different set of equipment in a separate box, for each type of analysis. For each kind of analysis, alterations to the apparatus are involved but these can be carried out with the basic set in position in a shielded cell, although to do so it is necessary to obtain access via the gloves on the fibre-glass inner glove box. This requires a removal of samples emitting radiation, by transfer to an adjoining cell. A single vacuum system is employed. This is connected through a plug in the lead wall of the shielded cell, and couplings in the glove box wall to the appropriate furnaces. Carbon may be determined, in stainless steel containing 400 to 800 ppm C, with a coefficient of variation of +- 2%. On deposits containing carbon, the coefficient of variation is better than +- 1% for 2 to 30 mg of carbon. Hydrogen, at levels between 30 and 200 ppm in titanium can be determined with a coefficient of variation of better than +- 5%. Titanium has been used in lieu of zircaloy since standardised zircaloy specimens are not available. The precision for oxygen/metal ratio is estimated to be +- 0.001 Atoms oxygen. Sample weights of 200 mg are adequate for most analyses. (author)

  2. Pecan shell-based granular activated carbon for treatment of chemical oxygen demand (COD) in municipal wastewater.

    Science.gov (United States)

    Bansode, R R; Losso, J N; Marshall, W E; Rao, R M; Portier, R J

    2004-09-01

    The present investigation was undertaken to compare the adsorption efficiency of pecan shell-based granular activated carbon with the adsorption efficiency of the commercial carbon Filtrasorb 200 with respect to uptake of the organic components responsible for the chemical oxygen demand (COD) of municipal wastewater. Adsorption efficiencies for these two sets of carbons (experimental and commercial) were analyzed by the Freundlich adsorption model. The results indicate that steam-activated and acid-activated pecan shell-based carbons had higher adsorption for organic matter measured as COD, than carbon dioxide-activated pecan shell-based carbon or Filtrasorb 200 at all the carbon dosages used during the experiment. The higher adsorption may be related to surface area as the two carbons with the highest surface area also had the highest organic matter adsorption. These results show that granular activated carbons made from agricultural waste (pecan shells) can be used with greater effectiveness for organic matter removal from municipal wastewater than a coal-based commercial carbon. Copyright 2004 Elsevier Ltd.

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

    Science.gov (United States)

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

    2015-10-20

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

  4. Nonlinear optical and optical limiting properties of fullerene, multi-walled carbon nanotubes, graphene and their derivatives with oxygen-containing functional groups

    International Nuclear Information System (INIS)

    Zhang, Xiao-Liang; Li, Xiao-Chun; Liu, Zhi-Bo; Yan, Xiao-Qing; Tian, Jian-Guo; Chen, Yong-Sheng

    2015-01-01

    Nonlinear optical properties (NLO) and optical limiting effect of fullerene (C 60 ), multi-walled carbon nanotubes (MWNTs), reduced graphene oxide (RGO) and their oxygenated derivatives were investigated by open-aperture Z-scan technique with nanosecond pulses at 532 nm. C 60 functionalized by oxygen-containing functional groups exhibits weaker NLO properties than that of pristine C 60 . Graphene oxide (GO) with many oxygen-containing functional groups also shows weaker NLO properties than that of RGO. That can be attributed to the disruption of conjugative structures of C 60 and graphene by oxygen-containing functional groups. However, MWNTs and their oxygenated derivatives exhibit comparable NLO properties due to the small weight ratio of these oxygen-containing groups. To investigate the correlation between structures and NLO response for these carbon nanomaterials with different dimensions, nonlinear scattered signal spectra versus input fluence were also measured. (paper)

  5. Oxygenation measurement by multi-wavelength oxygen-dependent phosphorescence and delayed fluorescence: catchment depth and application in intact heart

    NARCIS (Netherlands)

    Balestra, Gianmarco M.; Aalders, Maurice C. G.; Specht, Patricia A. C.; Ince, Can; Mik, Egbert G.

    2015-01-01

    Oxygen delivery and metabolism represent key factors for organ function in health and disease. We describe the optical key characteristics of a technique to comprehensively measure oxygen tension (PO(2)) in myocardium, using oxygen-dependent quenching of phosphorescence and delayed fluorescence of

  6. Determinants of oxygen and carbon dioxide transfer during extracorporeal membrane oxygenation in an experimental model of multiple organ dysfunction syndrome.

    Science.gov (United States)

    Park, Marcelo; Costa, Eduardo Leite Vieira; Maciel, Alexandre Toledo; Silva, Débora Prudêncio E; Friedrich, Natalia; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Schettino, Guilherme; Azevedo, Luciano Cesar Pontes

    2013-01-01

    Extracorporeal membrane oxygenation (ECMO) has gained renewed interest in the treatment of respiratory failure since the advent of the modern polymethylpentene membranes. Limited information exists, however, on the performance of these membranes in terms of gas transfers during multiple organ failure (MOF). We investigated determinants of oxygen and carbon dioxide transfer as well as biochemical alterations after the circulation of blood through the circuit in a pig model under ECMO support before and after induction of MOF. A predefined sequence of blood and sweep flows was tested before and after the induction of MOF with fecal peritonitis and saline lavage lung injury. In the multivariate analysis, oxygen transfer had a positive association with blood flow (slope = 66, Pmembrane PaCO(2) (slope = -0.96, P = 0.001) and SatO(2) (slope = -1.7, Ptransfer had a positive association with blood flow (slope = 17, Pmembrane PaCO(2) (slope = 1.2, Ptransfers were significantly determined by blood flow. Oxygen transfer was modulated by the pre-membrane SatO(2) and CO(2), while carbon dioxide transfer was affected by the gas flow, pre-membrane CO(2) and hemoglobin.

  7. Bosch Reactor Development for High Percentage Oxygen Recovery from Carbon Dioxide

    Science.gov (United States)

    Howard, David; Abney, Morgan

    2015-01-01

    This next Generation Life Support Project entails the development and demonstration of Bosch reaction technologies to improve oxygen recovery from metabolically generated oxygen and/or space environments. A primary focus was placed on alternate carbon formation reactor concepts to improve useful catalyst life for space vehicle applications, and make use of in situ catalyst resources for non-terrestrial surface missions. Current state-of-the-art oxygen recovery systems onboard the International Space Station are able to effectively recover approximately 45 percent of the oxygen consumed by humans and exhausted in the form of carbon dioxide (CO2). Excess CO2 is vented overboard and the oxygen contained in the molecules is lost. For long-duration missions beyond the reaches of Earth for resupply, it will be necessary to recover greater amounts of constituents such as oxygen that are necessary for sustaining life. Bosch technologies theoretically recover 100 percent of the oxygen from CO2, producing pure carbon as the sole waste product. Challenges with this technology revolve around the carbon product fouling catalyst materials, drastically limiting catalyst life. This project successfully demonstrated techniques to extend catalyst surface area exposure times to improve catalyst life for vehicle applications, and demonstrated the use of Martian and lunar regolith as viable catalyst Bosch Reactor Development for High Percentage Oxygen Recovery From Carbon Dioxide materials for surface missions. The Bosch process generates carbon nanotube formation within the regolith, which has been shown to improve mechanical properties of building materials. Production of bricks from post reaction regolith for building and radiation shielding applications were also explored.

  8. The measurement of oxygen in vivo using EPR techniques

    International Nuclear Information System (INIS)

    Swartz, Harold M.; Clarkson, Robert B.

    1998-01-01

    The measurement of pO 2 in vivo using EPR has some features which have already led to very useful applications and this approach is likely to have increasingly wide and effective use. It is based on the effect of oxygen on EPR spectra which provides a sensitive and accurate means to measure pO 2 quantitatively. The development of oxygen-sensitive paramagnetic materials which are very stable, combined with instrumental developments, has been crucial to the in vivo applications of this technique. The physical basis and biological applications of in vivo EPR oximetry are reviewed, with particular emphasis on the use of EPR spectroscopy at 1 GHz using particulate paramagnetic materials for the repetitive and non-invasive measurement of pO 2 in tissues. In vivo EPR has already produced some very useful results which have contributed significantly to solving important biological problems. The characteristics of EPR oximetry which appear to be especially useful are often complementary to existing techniques for measuring oxygen in tissues. These characteristics include the capability of making repeated measurements from the same site, high sensitivity to low levels of oxygen, and non-invasive options. The existing techniques are especially useful for studies in small animals, where the depth of measurements is not an overriding issue. In larger animals and potentially in human subjects, non-invasive techniques seem to be immediately applicable to study phenomena very near the surface (within 10 mm) while invasive techniques have some very promising uses. The clinical uses of EPR oximetry which seem especially promising and likely to be undertaken in the near future are long-term monitoring of the status and response to treatment of peripheral vascular disease and optimizing cancer therapy by enabling it to be modified on the basis of the pO 2 measured in the tumour. (author)

  9. The Kinetics of Oxygen Atom Recombination in the Presence of Carbon Dioxide

    Science.gov (United States)

    Jamieson, C. S.; Garcia, R. M.; Pejakovic, D.; Kalogerakis, K.

    2009-12-01

    Understanding processes involving atomic oxygen is crucial for the study and modeling of composition, energy transfer, airglow, and transport dynamics in planetary atmospheres. Significant gaps and uncertainties exist in the understanding of these processes and often the relevant input from laboratory measurements is missing or outdated. We are conducting laboratory experiments to measure the rate coefficient for O + O + CO2 recombination and investigating the O2 excited states produced following the recombination. These measurements will provide key input for a quantitative understanding and reliable modeling of the atmospheres of the CO2 planets and their airglow. An excimer laser providing pulsed output at either 193 nm or 248 nm is employed to produce O atoms by dissociating carbon dioxide, nitrous oxide, or ozone. In an ambient-pressure background of CO2, O atoms recombine in a time scale of a few milliseconds. Detection of laser-induced fluorescence at 845 nm following two-photon excitation near 226 nm monitors the decay of the oxygen atom population. From the temporal evolution of the signal the recombination rate coefficient is extracted. Fluorescence spectroscopy is used to detect the products of O-atom recombination and subsequent relaxation in CO2. This work is supported by the US National Science Foundation’s (NSF) Planetary Astronomy Program. Rosanne Garcia’s participation was funded by the NSF Research Experiences for Undergraduates (REU) Program.

  10. Observer-based Coal Mill Control using Oxygen Measurements

    DEFF Research Database (Denmark)

    Andersen, Palle; Bendtsen, Jan Dimon; S., Tom

    2006-01-01

    This paper proposes a novel approach to coal flow estimation in pulverized coal mills, which utilizes measurements of oxygen content in the flue gas. Pulverized coal mills are typically not equipped with sensors that detect the amount of coal injected into the furnace. This makes control...... of the coal flow difficult, causing stability problems and limits the plant's load following capabilities. To alleviate this problem without having to rely on expensive flow measurement equipment, a novel observer-based approach is investigated. A Kalman filter based on measurements of combustion air flow led...... into the furnace and oxygen concentration in the flue gas is designed to estimate the actual coal flow injected into the furnace. With this estimate, it becomes possible to close an inner loop around the coal mill itself, thus giving a better disturbance rejection capability. The approach is validated against...

  11. Direct measurements of the light dependence of gross photosynthesis and oxygen consumption in the ocean

    Science.gov (United States)

    Bailleul, B.; Park, J.; Brown, C. M.; Bidle, K. D.; Lee, S.; Falkowski, P. G.

    2016-02-01

    For decades, a lack of understanding of how respiration is influenced by light has been stymying our ability to quantitatively analyze how phytoplankton allocate carbon in situ and the biological mechanisms that participate to the fate of blooms. Using membrane inlet mass spectrometry (MIMS), the light dependencies of gross photosynthesis and oxygen uptake rates were measured during the bloom demises of two prymnesiophytes, in two open ocean regions. In the North Atlantic, dominated by Emiliania huxleyi, respiration was independent of irradiance and was higher than the gross photosynthetic rate at all irradiances. In the Amundsen Sea (Antarctica), dominated by Phaeocystis antarctica, the situation was very different. Dark respiration was one order of magnitude lower than the maximal gross photosynthetic rate. ut the oxygen uptake rate increased by 10 fold at surface irradiances, where it becomes higher than gross photosynthesis. Our results suggest that the light dependence of oxygen uptake in P. antarctica has two sources: one is independent of photosynthesis, and is possibly associated with the photo-reduction of O2 mediated by dissolved organic matter; the second reflects the activity of an oxidase fueled in the light with photosynthetic electron flow. Interestingly, these dramatic light-dependent changes in oxygen uptake were not reproduced in nutrient-replete P. antarctica cultures, in the laboratory. Our measurements highlight the importance of improving our understanding of oxygen consuming reactions in the euphotic zone, which is critical to investigating the physiology of phytoplankton and tracing the fate of phytoplankton blooms.

  12. Measuring oxygen uptake in fishes with bimodal respiration.

    Science.gov (United States)

    Lefevre, S; Bayley, M; McKenzie, D J

    2016-01-01

    Respirometry is a robust method for measurement of oxygen uptake as a proxy for metabolic rate in fishes, and how species with bimodal respiration might meet their demands from water v. air has interested researchers for over a century. The challenges of measuring oxygen uptake from both water and air, preferably simultaneously, have been addressed in a variety of ways, which are briefly reviewed. These methods are not well-suited for the long-term measurements necessary to be certain of obtaining undisturbed patterns of respiratory partitioning, for example, to estimate traits such as standard metabolic rate. Such measurements require automated intermittent-closed respirometry that, for bimodal fishes, has only recently been developed. This paper describes two approaches in enough detail to be replicated by the interested researcher. These methods are for static respirometry. Measuring oxygen uptake by bimodal fishes during exercise poses specific challenges, which are described to aid the reader in designing experiments. The respiratory physiology and behaviour of air-breathing fishes is very complex and can easily be influenced by experimental conditions, and some general considerations are listed to facilitate the design of experiments. Air breathing is believed to have evolved in response to aquatic hypoxia and, probably, associated hypercapnia. The review ends by considering what realistic hypercapnia is, how hypercapnic tropical waters can become and how this might influence bimodal animals' gas exchange. © 2015 The Fisheries Society of the British Isles.

  13. The Reduction Reaction of Dissolved Oxygen in Water by Hydrazine over Platinum Catalyst Supported on Activated Carbon Fiber

    Energy Technology Data Exchange (ETDEWEB)

    Park, K.K.; Moon, J.S. [Korea Electric Power Research Institute, Taejon (Korea)

    1999-07-01

    The reduction reaction of dissolved oxygen (DO) by hydrazine was investigated on activated carbon fiber (ACF) and Pt/ACF catalysts using a batch reactor with an external circulating loop. The ACF itself showed catalytic activity and this was further improved by supporting platinum on ACF. The catalytic role platinum is ascribed to its acceleration of hydrazine decomposition, based on electric potential and current measurements as well as the kinetic study. (author). 15 refs., 13 figs.

  14. 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

  15. Oxygen-rich hierarchical porous carbon made from pomelo peel fiber as electrode material for supercapacitor

    Science.gov (United States)

    Li, Jing; Liu, Wenlong; Xiao, Dan; Wang, Xinhui

    2017-09-01

    Oxygen-rich hierarchical porous carbon has been fabricated using pomelo peel fiber as a carbon source via an improved KOH activation method. The morphology and chemical composition of the obtained carbon materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), electron microscopy (EM), Raman spectra and elemental analysis. The unique porous structure with abundant oxygen functional groups is favorable to capacitive behavior, and the as-prepared carbon material exhibits high specific capacitance of 222.6 F g-1 at 0.5 A g-1 in 6 M KOH and superior stability over 5000 cycles. This work not only describes a simple way to prepare high-performance carbon material from the discarded pomelo peel, but also provides a strategy for its disposal issue and contributes to the environmental improvement.

  16. Some TPC measurements in an oxygen beam at the AGS

    International Nuclear Information System (INIS)

    Love, W.A.; Etkin, A.; Foley, K.J.; Hackenburg, R.W.; Longacre, R.S.; Morris, T.W.; Platner, E.D.; Saulys, A.C.; Bonner, B.E.; Buchanan, J.A.; Chiou, C.N.; Clement, J.M.; Corcoran, M.D.; Krishna, N.; Kruk, J.W.; Miettinen, H.E.; Mutchler, G.S.; Nessi-Tedaldi, F.; Nessi, M.; Phillips, G.C.; Roberts, J.B.; Chan, C.S.; Kramer, M.A.; Hallman, T.J.; Madansky, L.; Lindenbaum, S.J.

    1989-01-01

    The principal detector for AGS Experiment 810 is a Time Projection Chamber (TPC) in which it is intended to measure momenta and angles of a major fraction of the charged particles from each light ion collision. This report describes the results of a test of a prototype of the TPC in a beam of (14.6x16=233.6 GeV/c) oxygen ions run in June of this year. (orig.)

  17. Effect of electron injection on defect reactions in irradiated silicon containing boron, carbon, and oxygen

    Science.gov (United States)

    Makarenko, L. F.; Lastovskii, S. B.; Yakushevich, H. S.; Moll, M.; Pintilie, I.

    2018-04-01

    Comparative studies employing Deep Level Transient Spectroscopy and C-V measurements have been performed on recombination-enhanced reactions between defects of interstitial type in boron doped silicon diodes irradiated with alpha-particles. It has been shown that self-interstitial related defects which are immobile even at room temperatures can be activated by very low forward currents at liquid nitrogen temperatures. Their activation is accompanied by the appearance of interstitial carbon atoms. It has been found that at rather high forward current densities which enhance BiOi complex disappearance, a retardation of Ci annealing takes place. Contrary to conventional thermal annealing of the interstitial boron-interstitial oxygen complex, the use of forward current injection helps to recover an essential part of charge carriers removed due to irradiation.

  18. Quantitative Romberg's test in acute carbon monoxide poisoning treated by hyperbaric oxygen

    DEFF Research Database (Denmark)

    Bidstrup, Daniel; Jansen, Erik Christian; Hyldegaard, Ole

    2017-01-01

    LMM, sway prior to HBO₂ therapy was set as the fixed effect and change in sway after HBO₂ therapy was set as the response variable. Patient, treatment number, weight and age were set as random effects for all LMMs. RESULTS: From the LMMs we found that larger values of sway prior to HBO₂ produced......OBJECTIVE: The aim of this study was to evaluate whether monitoring of acute carbon monoxide-poisoned (COP) patients by means of quantitative Romberg's test (QR-test) during a hyperbaric oxygen (HBO₂) therapy regimen could be a useful supplement in the evaluation of neurological status. METHODS: We...... conducted a retrospective study (2000-2014) in which we evaluated data containing quantitative sway measurements of acute COP patients (n = 58) treated in an HBO₂ regimen. Each patient was tested using QR-test before and after each HBO₂ treatment. Data were analyzed using linear mixed models (LMM). In each...

  19. Tissue oxygenation and haemodynamics measurement with spatially resolved NIRS

    Science.gov (United States)

    Zhang, Y.; Scopesi, F.; Serra, G.; Sun, J. W.; Rolfe, P.

    2010-08-01

    We describe the use of Near Infrared Spectroscopy (NIRS) for the non-invasive investigation of changes in haemodynamics and oxygenation of human peripheral tissues. The goal was to measure spatial variations of tissue NIRS oxygenation variables, namely deoxy-haemoglobin (HHb), oxy-haemoglobin (HbO2), total haemoglobin (HbT), and thereby to evaluate the responses of the peripheral circulation to imposed physiological challenges. We present a skinfat- muscle heterogeneous tissue model with varying fat thickness up to 15mm and a Monte Carlo simulation of photon transport within this model. The mean partial path length and the mean photon visit depth in the muscle layer were derived for different source-detector spacing. We constructed NIRS instrumentation comprising of light-emitting diodes (LED) as light sources at four wavelengths, 735nm, 760nm, 810nm and 850nm and sensitive photodiodes (PD) as the detectors. Source-detector spacing was varied to perform measurements at different depths within forearm tissue. Changes in chromophore concentration in response to venous and arterial occlusion were calculated using the modified Lambert-Beer Law. Studies in fat and thin volunteers indicated greater sensitivity in the thinner subjects for the tissue oxygenation measurement in the muscle layer. These results were consistent with those found using Monte Carlo simulation. Overall, the results of this investigation demonstrate the usefulness of the NIRS instrument for deriving spatial information from biological tissues.

  20. Carbon fiber content measurement in composite

    Science.gov (United States)

    Wang, Qiushi

    Carbon fiber reinforced polymers (CFRPs) have been widely used in various structural applications in industries such as aerospace and automotive because of their high specific stiffness and specific strength. Their mechanical properties are strongly influenced by the carbon fiber content in the composites. Measurement of the carbon fiber content in CFRPs is essential for product quality control and process optimization. In this work, a novel carbonization-in-nitrogen method (CIN) is developed to characterize the fiber content in carbon fiber reinforced thermoset and thermoplastic composites. In this method, a carbon fiber composite sample is carbonized in a nitrogen environment at elevated temperatures, alongside a neat resin sample. The carbon fibers are protected from oxidization while the resin (the neat resin and the resin matrix in the composite sample) is carbonized under the nitrogen environment. The residue of the carbonized neat resin sample is used to calibrate the resin carbonization rate and calculate the amount of the resin matrix in the composite sample. The new method has been validated on several thermoset and thermoplastic resin systems and found to yield an accurate measurement of fiber content in carbon fiber polymer composites. In order to further understand the thermal degradation behavior of the high temperature thermoplastic polymer during the carbonization process, the mechanism and the kinetic model of thermal degradation behavior of carbon fiber reinforced poly (phenylene sulfide) (CPPS) are studied using thermogravimetry analysis (TGA). The CPPS is subjected to TGA in an air and nitrogen atmosphere at heating rates from 5 to 40°C min--1. The TGA curves obtained in air are different from those in nitrogen. This demonstrates that weight loss occurs in a single stage in nitrogen but in two stages in air. To elucidate this difference, thermal decomposition kinetics is analyzed by applying the Kissinger, Flynn-Wall-Ozawa, Coat-Redfern and

  1. Long-term ocean oxygen depletion in response to carbon dioxide emissions from fossil fuels

    DEFF Research Database (Denmark)

    Shaffer, G.; Olsen, S.M.; Pedersen, Jens Olaf Pepke

    2009-01-01

    Ongoing global warming could persist far into the future, because natural processes require decades to hundreds of thousands of years to remove carbon dioxide from fossil-fuel burning from the atmosphere(1-3). Future warming may have large global impacts including ocean oxygen depletion and assoc......Ongoing global warming could persist far into the future, because natural processes require decades to hundreds of thousands of years to remove carbon dioxide from fossil-fuel burning from the atmosphere(1-3). Future warming may have large global impacts including ocean oxygen depletion...... solubility from surface-layer warming accounts for most of the enhanced oxygen depletion in the upper 500 m of the ocean. Possible weakening of ocean overturning and convection lead to further oxygen depletion, also in the deep ocean. We conclude that substantial reductions in fossil-fuel use over the next...

  2. Southern Ocean Carbon Dioxide and Oxygen Fluxes Detected by SOCCOM Biogeochemical Profiling Floats

    Science.gov (United States)

    Sarmiento, J. L.; Bushinksy, S.; Gray, A. R.

    2016-12-01

    The Southern Ocean is known to play an important role in the global carbon cycle, yet historically our measurements of this remote region have been sparse and heavily biased towards summer. Here we present new estimates of air-sea fluxes of carbon dioxide and oxygen calculated with measurements from autonomous biogeochemical profiling floats. At high latitudes in and southward of the Antarctic Circumpolar Current, we find a significant flux of CO2 from the ocean to the atmosphere during 2014-2016, which is particularly enhanced during winter months. These results suggest that previous estimates may be biased towards stronger Southern Ocean CO2 uptake due to undersampling in winter. We examine various implications of having a source of CO2 that is higher than previous estimates. We also find that CO2:O2 flux ratios north of the Subtropical Front are positive, consistent with the fluxes being driven by changes in solubility, while south of the Polar Front biological processes and upwelling of deep water combine to produce a negative CO2:O2 flux ratio.

  3. Atmospheric oxygen regulation at low Proterozoic levels by incomplete oxidative weathering of sedimentary organic carbon

    Science.gov (United States)

    Daines, Stuart J.; Mills, Benjamin J. W.; Lenton, Timothy M.

    2017-02-01

    It is unclear why atmospheric oxygen remained trapped at low levels for more than 1.5 billion years following the Paleoproterozoic Great Oxidation Event. Here, we use models for erosion, weathering and biogeochemical cycling to show that this can be explained by the tectonic recycling of previously accumulated sedimentary organic carbon, combined with the oxygen sensitivity of oxidative weathering. Our results indicate a strong negative feedback regime when atmospheric oxygen concentration is of order pO2~0.1 PAL (present atmospheric level), but that stability is lost at pO2counterbalancing changes in the weathering of isotopically light organic carbon. This can explain the lack of secular trend in the Precambrian δ13C record, and reopens the possibility that increased biological productivity and resultant organic carbon burial drove the Great Oxidation Event.

  4. Radiation hardness of silicon detectors manufactured on epitaxial material and FZ bulk enriched with oxygen, carbon, tin and platinum

    CERN Document Server

    Ruzin, A; Glaser, M; Lemeilleur, F; Talamonti, R; Watts, S; Zanet, A

    1999-01-01

    Recent results on the radiation hardness of silicon detectors fabricated on epitaxial and float zone bulk silicon enriched by various impurities, such as carbon, oxygen, tin and platinum are reported. A new methodology of measurements of electrical properties of the devices has been utilized in the experiment. It has been shown that in the case of irradiation by protons, oxygen enriched silicon has better radiation hardness than standard float zone silicon. The carbon enriched silicon detectors, on the other hand, exhibited significantly inferior radiation hardness compared to standard detectors. This study shows for the first time, a violation of the widely used normalization technique of the various particle irradiations by NIEL coefficients. The study has been carried out in the framework of the RD48 (ROSE) collaboration, which studies the radiation hardening of silicon detectors. (5 refs).

  5. [Cerebellar Infarction After Carbon Monoxide Poisoning and Hyperbaric Oxygen Therapy].

    Science.gov (United States)

    Wick, Matthias; Schneiker, André; Bele, Sylvia; Pawlik, Michael; Meyringer, Helmut; Graf, Bernhard; Wendl, Christina; Kieninger, Martin

    2017-06-01

    We report on a patient who developed a space-occupying cerebellar infarction with occlusive hydrocephalus after a poisoning with carbon monoxide with the intention to commit suicide. A neurosurgical and intensive care therapy were needed. The patient's survival without severe neurological deficits could be secured due to the early detection of the intracerebral lesions. Georg Thieme Verlag KG Stuttgart · New York.

  6. Hydrogen, carbon and oxygen determination in proxy material samples using a LaBr3:Ce detector.

    Science.gov (United States)

    Naqvi, A A; Al-Matouq, Faris A; Khiari, F Z; Isab, A A; Raashid, M; Khateeb-ur-Rehman

    2013-08-01

    Hydrogen, carbon and oxygen concentrations were measured in caffeine, urea, ammonium acetate and melamine bulk samples via 14 MeV neutron inelastic scattering using a LaBr3:Ce detector. The samples tested herein represent drugs, explosives and benign materials, respectively. Despite its intrinsic activity, the LaBr3:Ce detector performed well in detecting the hydrogen, carbon and oxygen elements. Because 5.1 MeV nitrogen gamma rays interfere with silicon and calcium prompt gamma rays from the room background, the nitrogen peak was not detected in the samples. An excellent agreement was observed between the experimental and theoretical yields of 2.22, 4.43 and 6.13 MeV gamma rays from the analyzed samples as a function of H, C and O concentrations, respectively. Within statistical errors, the minimum detectable concentration (MDC) of hydrogen, carbon and oxygen elements in the tested materials were consistent with previously reported MDC values for these elements measured in hydrocarbon samples. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Optical Absorptions of Oxygenated Carbon Chain Cations in the Gas Phase

    Science.gov (United States)

    Hardy, F.-X.; Rice, C. A.; Chakraborty, A.; Fulara, J.; Maier, J. P.

    2016-06-01

    The gas-phase electronic spectra of linear OC4O+ and a planar C6H2O+ isomer were obtained at a rotational temperature of ≈10 K. Absorption measurements in a 6 K neon matrix were followed by gas-phase observations in a cryogenic radiofrequency ion trap. The origin bands of the 1{}2{{{\\Pi }}}u ≤ftarrow X{}2{{{\\Pi }}}g transition of OC4O+ and the 1{}2A{}2 ≤ftarrow X{}2B1 of HCCC(CO)CCH+ lie at 417.31 ± 0.01 nm and 523.49 ± 0.01 nm, respectively. These constitute the first electronic spectra of oxygenated carbon chain cations studied under conditions that are relevant to the diffuse interstellar bands (DIBs), as both have a visible transition. The recent analysis of the 579.5 nm DIB indicates that small carriers, five to seven heavy atoms, continue to be possible candidates (Huang & Oka 2015). Astronomical implications are discussed regarding this kind of oxygenated molecules.

  8. Effect of inundation, oxygen and temperature on carbon mineralization in boreal ecosystems.

    Science.gov (United States)

    Kim, Youngil; Ullah, Sami; Roulet, Nigel T; Moore, Tim R

    2015-04-01

    The inundation of boreal forests and peatlands through the construction of hydroelectric reservoirs can increase carbon dioxide (CO2) and methane (CH4) emission. To establish controls on emission rates, we incubated samples of forest and peat soils, spruce litter, forest litter and peatland litter collected from boreal ecosystems in northern Quebec for 16 weeks and measured CO2 and CH4 production rates under flooded or non-flooded conditions and varying oxygen concentration and temperature. CO2 production under flooded conditions was less than under non-flooded conditions (5-71 vs. 5-85 mg Cg(-1) C), but CH4 production under flooded conditions was larger than under non-flooded conditions (1-8158 vs. 0-86 μg Cg(-1) C). The average CO2 and CH4 production rate factor for flooded:non-flooded conditions was 0.76 and 1.32, respectively. Under flooded conditions, high oxygen concentrations increased CO2 production in peat soils but decreased CH4 production in forest and peat soils and spruce litter. Warmer temperatures (from 4 to 22°C) raised both CO2 production in peat soils and peatland litter, and CH4 production in peat soils and spruce litter. This study shows that the direction and/or strength of CO2 and CH4 fluxes change once boreal forests and peatlands are inundated. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Low energy electron irradiation induced carbon etching: Triggering carbon film reacting with oxygen from SiO{sub 2} substrate

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Cheng [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China); Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Wang, Chao, E-mail: cwang367@szu.edu.cn, E-mail: dfdiao@szu.edu.cn; Diao, Dongfeng, E-mail: cwang367@szu.edu.cn, E-mail: dfdiao@szu.edu.cn [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China)

    2016-08-01

    We report low-energy (50–200 eV) electron irradiation induced etching of thin carbon films on a SiO{sub 2} substrate. The etching mechanism was interpreted that electron irradiation stimulated the dissociation of the carbon film and SiO{sub 2}, and then triggered the carbon film reacting with oxygen from the SiO{sub 2} substrate. A requirement for triggering the etching of the carbon film is that the incident electron penetrates through the whole carbon film, which is related to both irradiation energy and film thickness. This study provides a convenient electron-assisted etching with the precursor substrate, which sheds light on an efficient pathway to the fabrication of nanodevices and nanosurfaces.

  10. Oxygen and carbon isotopic compositions of gases respired by humans

    International Nuclear Information System (INIS)

    Epstein, S.; Zeiri, L.

    1988-01-01

    Oxygen-isotope fractionation associated with respiration in human individuals at rest is linearly related to the fraction of the O 2 utilized in the respiration process. The slope of this relationship is affected by a history of smoking, by vigorous exercise, and by the N 2 /O 2 ratio of the inhaled gas. For patients who suffer anemia-related diseases, the slope of this relationship is directly proportional to their level of hemoglobin. These results introduce a new approach for studying the mechanisms of O 2 consumption in human respiration and how they are affected by related diseases

  11. Oxygen- and nitrogen-co-doped activated carbon from waste particleboard for potential application in high-performance capacitance

    International Nuclear Information System (INIS)

    Shang, Tong-Xin; Ren, Ru-Quan; Zhu, Yue-Mei; Jin, Xiao-Juan

    2015-01-01

    Graphical abstract: All electrodes showed excellent capacitance and retention versus discharge current density from 0.05 to 5 A/g. - Abstract: Oxygen- and nitrogen-co-doped activated carbons were obtained from phosphoric acid treated nitrogen-doped activated carbons which were prepared from waste particleboard bonded with urea-formaldehyde resin adhesives. The activated carbon samples obtained were tested as supercapacitors in two-electrode cell and extensive wetting 7 M KOH electrolytes. Their structural properties and surface chemistry, before the electrical testing, were investigated using elemental analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, X-ray diffraction, Raman spectra, and adsorption of nitrogen. Activated carbon treated by 4 M phosphoric acid of the highest capacitance (235 F/g) was measured in spite of a relatively lower surface (1360 m 2 /g) than that of the activated carbon treated by 2 M phosphoric acid (1433 m 2 /g). The surface chemistry, and especially oxygen- and nitrogen-containing functional groups, was found of paramount importance for the capacitive behavior and for the effective pore space utilization by the electrolyte ions

  12. Application of carbon and oxygen stable isotopes to the study of Brazilian precambrian

    International Nuclear Information System (INIS)

    Torquato, J.R.F.

    1980-01-01

    Samples of carbonated rocks of precambrian age are studied. The stable carbon and oxygen isotopes are applied to the study of terrestrial materials considering the variations of some element isotopic composition in function of the environment of sedimentation. The isotopic analysis was done using mass spectrometers. The analytical results and the description of region geology of the site of each sample are presented. The isotopic data are interpreted aiming to the environment of sedimentation. New techniques for better improvement of carbon and oxygen ratios, are proposed, such as: to use the analysis of surface trend and the isotopic logging in mapping of surface and subsurface. A new method for approximated determination of the ages of precambrian carbonated rocks, considering the limitations of their new technique, is also presented. (M.C.K.) [pt

  13. Effect of dissolved oxygen on biological denitrification using biodegradable plastic as the carbon source

    Science.gov (United States)

    Zhang, Xucai; Zhang, Jianmei

    2018-02-01

    Biological denitrification is currently a common approach to remove nitrate from wastewater. This study was conducted to evaluate the influence of dissolved oxygen on denitrification in wastewater treatment using biodegradable plastic as carbon source by designing the aerated, anoxic, and low-oxygen experimental treatment groups. The results showed that the removal rates of nitrate in anoxic and low-oxygen groups were 30.6 g NO3 --Nm-3 d-1 and 30.8 g NO3 --N m-3 d-1 at 83 h, respectively, both of which were higher than that of the aerated group. There was no significant difference between the anoxic and low-oxygen treatment groups for the nitrate removal. Additional, the nitrite accumulated during the experiments, and the nitrite concentrations in anoxic and aerated groups were lower than those in low-oxygen group. No nitrite was detected in all groups at the end of the experiments. These findings indicated that dissolved oxygen has important influence on denitrification, and anoxic and low-oxygen conditions can support completely denitrification when using BP as carbon source in nitrate-polluted wastewater treatment.

  14. Integration of Carbon, Nitrogen, and Oxygen Metabolism in Escherichia coli

    Science.gov (United States)

    2012-10-22

    optimally, balancing effectively the conversion of carbon into energy versus biomass . To investigate the link between the metabolism of different nutrients...diverse nutrient conditions, E. coli  grows nearly optimally, balancing effectively the  conversion  of carbon  into energy versus  biomass . Here we  show... enzymatic  connections, with kinetic parameters taken from the  literature or computationally  inferred  based on  the data  from Aim 1. As proposed  initially

  15. Spontaneous oxygen isotope exchange between carbon dioxide and\

    Czech Academy of Sciences Publication Activity Database

    Knížek, Antonín; Zukalová, Markéta; Kavan, Ladislav; Zukal, Arnošt; Kubelík, Petr; Rojík, P.; Skřehot, P.; Ferus, Martin; Civiš, Svatopluk

    2017-01-01

    Roč. 137, MAR 2017 (2017), s. 6-10 ISSN 0169-1317 R&D Projects: GA MŠk LD14115; GA ČR(CZ) GA14-12010S; GA ČR GA13-07724S; GA MŠk(CZ) LM2015073 Institutional support: RVO:61388955 Keywords : clay * carbon dioxide * FTIR spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.101, year: 2016

  16. Synthesis of Heteroaromatic Compounds by Oxidative Aromatization Using an Activated Carbon/Molecular Oxygen System

    Directory of Open Access Journals (Sweden)

    Masahiko Hayashi

    2009-08-01

    Full Text Available A variety of heteroaromatic compounds, such as substituted pyridines, pyrazoles, indoles, 2-substituted imidazoles, 2-substituted imidazoles, 2-arylbenzazoles and pyrimidin-2(1H-ones are synthesized by oxidative aromatization using the activated carbon and molecular oxygen system. Mechanistic study focused on the role of activated carbon in the synthesis of 2-arylbenzazoles is also discussed. In the final section, we will disclose the efficient synthesis of substituted 9,10-anthracenes via oxidative aromatization.

  17. Get better cased well data with the carbon/oxygen log

    International Nuclear Information System (INIS)

    Fertl, W.H.; Frost, E.

    1982-01-01

    Using case studies from heavy oil environments in the U.S. and Canada, it is shown how the continuous carbon/oxygen log, a type of pulsed neutron log, has proven an effective cased-hole reservoir evaluation and monitoring device. The article is a follow-up to one last month that detailed how the C/O log operates and reviewed case studies of its use in sandstone and carbonate environments

  18. Ion measurements in premixed methane-oxygen flames

    KAUST Repository

    Alquaity, Awad

    2014-07-25

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

  19. N-Doped Carbon Xerogels as Pt Support for the Electro-Reduction of Oxygen

    Directory of Open Access Journals (Sweden)

    Cinthia Alegre

    2017-09-01

    Full Text Available Durability and limited catalytic activity are key impediments to the commercialization of polymer electrolyte fuel cells. Carbon materials employed as catalyst support can be doped with different heteroatoms, like nitrogen, to improve both catalytic activity and durability. Carbon xerogels are nanoporous carbons that can be easily synthesized in order to obtain N-doped materials. In the present work, we introduced melamine as a carbon xerogel precursor together with resorcinol for an effective in-situ N doping (3–4 wt % N. Pt nanoparticles were supported on nitrogen-doped carbon xerogels and their activity for the oxygen reduction reaction (ORR was evaluated in acid media along with their stability. Results provide new evidences of the type of N groups aiding the activity of Pt for the ORR and of a remarkable stability for N-doped carbon-supported Pt catalysts, providing appropriate physico-chemical features.

  20. Airborne Lidar Measurements of Atmospheric Pressure Made Using the Oxygen A-Band

    Science.gov (United States)

    Riris, Haris; Rodriquez, Michael D.; Allan, Graham R.; Hasselbrack, William E.; Mao, Jianping; Stephen, Mark A.; Abshire, James B.

    2012-01-01

    Accurate measurements of greenhouse gas mixing ratios on a global scale are currently needed to gain a better understanding of climate change and its possible impact on our planet. In order to remotely measure greenhouse gas concentrations in the atmosphere with regard to dry air, the air number density in the atmosphere is also needed in deriving the greenhouse gas concentrations. Since oxygen is stable and uniformly mixed in the atmosphere at 20.95%, the measurement of an oxygen absorption in the atmosphere can be used to infer the dry air density and used to calculate the dry air mixing ratio of a greenhouse gas, such as carbon dioxide or methane. OUT technique of measuring Oxygen uses integrated path differential absorption (IPDA) with an Erbium Doped Fiber Amplifier (EDF A) laser system and single photon counting module (SPCM). It measures the absorbance of several on- and off-line wavelengths tuned to an O2 absorption line in the A-band at 764.7 nm. The choice of wavelengths allows us to maximize the pressure sensitivity using the trough between two absorptions in the Oxygen A-band. Our retrieval algorithm uses ancillary meteorological and aircraft altitude information to fit the experimentally obtained lidar O2 line shapes to a model atmosphere and derives the pressure from the profiles of the two lines. We have demonstrated O2 measurements from the ground and from an airborne platform. In this paper we will report on our airborne measurements during our 2011 campaign for the ASCENDS program.

  1. Controlling porosity of porous carbon cathode for lithium oxygen batteries: Influence of micro and meso porosity

    Science.gov (United States)

    Kim, Minjae; Yoo, Eunjoo; Ahn, Wha-Seung; Shim, Sang Eun

    2018-06-01

    In rechargeable lithium-oxygen (Li-O2) batteries, the porosity of porous carbon materials plays a crucial role in the electrochemical performance serving as oxygen diffusion path and Li ion transfer passage. However, the influence of optimization of porous carbon as an air electrode on cell electrochemical performance remains unclear. To understand the role of carbon porosity in Li-O2 batteries, carbon materials featuring controlled pore sizes and porosity, including C-800 (nearly 96% microporous) and AC-950 (55:45 micro/meso porosity), are designed and synthesized by carbonization using a triazine-based covalent organic polymer (TCOP). We find that the microporous C-800 cathode allows 120 cycles with a limited capacity of 1000 mAh g-1, about 2 and 10 times higher than that of mixed-porosity AC-950 and mesoporous CMK-3, respectively. Meanwhile, the specific discharge capacity of the C-800 electrode at 200 mA g-1 is 6003 mAh g-1, which is lower than that of the 8433 and 9960 mAh g-1 when using AC-950 and CMK-3, respectively. This difference in the electrochemical performance of the porous carbon cathode with different porosity causes to the generation and decomposition of Li2O2 during the charge and discharge cycle, which affects oxygen diffusion and Li ion transfer.

  2. Observer-Based Fuel Control Using Oxygen Measurement

    DEFF Research Database (Denmark)

    Andersen, Palle; Bendtsen, Jan Dimon; Mortensen, Jan Henrik

    is constructed and validated against data obtained at the plant. A Kalman filter based on measurements of combustion air flow led into the furnace and oxygen concentration in the flue gas is designed to estimate the actual coal flow. With this estimate, it becomes possible to close an inner loop around the coal......This report describes an attempt to improve the existing control af coal mills used at the Danish power plant Nordjyllandsværket Unit 3. The coal mills are not equipped with coal flow sensors; thus an observer-based approach is investigated. A nonlinear differential equation model of the boiler...

  3. Study by photoluminescence of centers associated to oxygen and carbon in silicon

    International Nuclear Information System (INIS)

    Lazrak, A.

    1984-12-01

    Results on analysis of luminescence of impurities in silicon are examined. Then in chapter 5, p. 76 to 91, irradiation of silicon by electrons is studied, interaction of defects created and diffusion, influence of carbon, oxygen and doping materials, annealing at 450 0 C, photoluminescence spectra are investigated [fr

  4. 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

  5. Oxygen and carbon isotope analyses of a Late Quaternary core in the Zaire (Congo) fan

    International Nuclear Information System (INIS)

    Olausson, E.

    1984-01-01

    Oxygen and carbon isotope analyses have been carried out on samples from a core of the Angola Basin (6 0 50'S, 10 0 45'E, depth 2100 m). The pelagic foraminifer Globigerinoides ruber, a species with a shallow water habitat, and two benthic species Uvigerina peregrina and Bulimina aculeata have been analysed. The data are given relative to PDB. (Auth.)

  6. ANALYTICAL EMPLOYMENT OF STABLE ISOTOPES OF CARBON, NITROGEN, OXYGEN AND HYDROGEN FOR FOOD AUTHENTICATION

    Directory of Open Access Journals (Sweden)

    E. Novelli

    2011-04-01

    Full Text Available Stable isotopes of carbon, nitrogen, oxygen and hydrogen were used for analytical purposes for the discrimination of the type of production (farming vs. fishing in the case of sea bass and for geographical origin in the case of milk. These results corroborate similar experimental evidences and confirm the potential of this analytical tool to support of food traceability.

  7. Using carbon emissions and oxygen consumption to estimate energetics parameters of cattle consuming forages

    Science.gov (United States)

    To evaluate newer indirect calorimetry system to quantify energetic parameters, 8 cross-bred beef steers (initial BW = 241 ± 4.10 kg) were used in a 77-d experiment to examine energetics parameters calculated from carbon dioxide (CO2), methane (CH4), and oxygen (O2) fluxes. Steers were individually ...

  8. Using carbon emissions, oxygen consumption, and retained energy to calculate dietary ME intake by beef steers

    Science.gov (United States)

    Eight cross-bred beef steers (initial BW = 241 ± 4.10 kg) were used in a 77-d feeding experiment to determine if ME intake can be determined from carbon emissions, oxygen consumption, and energy retention estimates. Steers were housed in a pen equipped with individual feed bunks and animal access w...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-28

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

  10. Carbon coated (carbonous) catalyst in ebullated bed reactor for production of oxygenated chemicals from syngas/CO2

    International Nuclear Information System (INIS)

    Peizheng Zhou

    2002-01-01

    This report summarizes the work completed under DOE's Support of Advanced Fuel Research program, Contract No. DE-FG26-99FT40681. The contract period was October 2000 through September 2002. This R and D program investigated the modification of the mechanical strength of catalyst extrudates using Hydrocarbon Technologies, Inc. (HTI) carbon-coated catalyst technology so that the ebullated bed technology can be utilized to produce valuable oxygenated chemicals from syngas/CO 2 efficiently and economically. Exothermic chemical reactions benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. The carbon-coated extrudates prepared using these procedures had sufficient attrition resistance and surface area for use in ebullated bed operation. The low cost of carbon coating makes the carbon-coated catalysts highly competitive in the market of catalyst extrudates

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

    Directory of Open Access Journals (Sweden)

    Hyungkyu Han

    2018-01-01

    Full Text Available The lithium oxygen battery is a promising energy storage system due to its high theoretical energy density and ability to use oxygen from air as a “fuel”. Although various carbonaceous materials have been widely used as a cathode material due to their high electronic conductivity and facial processability, previous studies mainly focused on the electrochemical properties associated with the materials (such as graphene and carbon nanotubes and the electrode configuration. Recent reports demonstrated that the polarization associated with cycling could be significantly increased by lithium carbonates generated from the reaction between the carbon cathode and an electrolyte, which indicates that the physicochemical properties of the carbon cathode could play an important role on the electrochemical performances. However, there is no systematic study to understand these phenomena. Here, we systematically explore the electrochemical properties of carbon nanofibers (CNF webs with different graphitization degree as a cathode for Li oxygen batteries. The physicochemical properties and electrochemical properties of CNF webs were carefully monitored before and after cycling. CNF webs are prepared at 1000, 1200 and 1400 °C. CNF web pyrolyzed at 1400 °C shows lowered polarization and improved cycle retention compared to those of CNF webs pyrolyzed at 1000 and 1200 °C.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  13. CARBON-TO-OXYGEN RATIOS IN M DWARFS AND SOLAR-TYPE STARS

    International Nuclear Information System (INIS)

    Nakajima, Tadashi; Sorahana, Satoko

    2016-01-01

    It has been suggested that high C/O ratios (>0.8) in circumstellar disks lead to the formation of carbon-dominated planets. Based on the expectation that elemental abundances in the stellar photospheres give the initial abundances in the circumstellar disks, the frequency distributions of C/O ratios of solar-type stars have been obtained by several groups. The results of these investigations are mixed. Some find C/O > 0.8 in more than 20% of stars, and C/O > 1.0 in more than 6%. Others find C/O > 0.8 in none of the sample stars. These works on solar-type stars are all differential abundance analyses with respect to the Sun and depend on the adopted C/O ratio in the Sun. Recently, a method of molecular line spectroscopy of M dwarfs, in which carbon and oxygen abundances are derived respectively from CO and H 2 O lines in the K band, has been developed. The resolution of the K- band spectrum is 20,000. Carbon and oxygen abundances of 46 M dwarfs have been obtained by this nondifferential abundance analysis. Carbon-to-oxygen ratios in M dwarfs derived by this method are more robust than those in solar-type stars derived from neutral carbon and oxygen lines in the visible spectra because of the difficulty in the treatment of oxygen lines. We have compared the frequency distribution of C/O distributions in M dwarfs with those of solar-type stars and have found that the low frequency of high-C/O ratios is preferred.

  14. CARBON-TO-OXYGEN RATIOS IN M DWARFS AND SOLAR-TYPE STARS

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Tadashi [Astrobiology Center, 2-21-1, Osawa, Mitaka, Tokyo, 181-8588 (Japan); Sorahana, Satoko, E-mail: tadashi.nakajima@nao.ac.jp, E-mail: sorahana@astron.s.u-tokyo.ac.jp [Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan)

    2016-10-20

    It has been suggested that high C/O ratios (>0.8) in circumstellar disks lead to the formation of carbon-dominated planets. Based on the expectation that elemental abundances in the stellar photospheres give the initial abundances in the circumstellar disks, the frequency distributions of C/O ratios of solar-type stars have been obtained by several groups. The results of these investigations are mixed. Some find C/O > 0.8 in more than 20% of stars, and C/O > 1.0 in more than 6%. Others find C/O > 0.8 in none of the sample stars. These works on solar-type stars are all differential abundance analyses with respect to the Sun and depend on the adopted C/O ratio in the Sun. Recently, a method of molecular line spectroscopy of M dwarfs, in which carbon and oxygen abundances are derived respectively from CO and H{sub 2}O lines in the K band, has been developed. The resolution of the K- band spectrum is 20,000. Carbon and oxygen abundances of 46 M dwarfs have been obtained by this nondifferential abundance analysis. Carbon-to-oxygen ratios in M dwarfs derived by this method are more robust than those in solar-type stars derived from neutral carbon and oxygen lines in the visible spectra because of the difficulty in the treatment of oxygen lines. We have compared the frequency distribution of C/O distributions in M dwarfs with those of solar-type stars and have found that the low frequency of high-C/O ratios is preferred.

  15. Biological fractionation of oxygen and carbon isotopes by recent benthic foraminifera

    International Nuclear Information System (INIS)

    Woodruff, F.; Douglas, R.G.

    1980-01-01

    Recent deep-sea benthic foraminifera from five East Pacific Rise box core tops have been analyzed for oxygen and carbon isotopic composition. The five equatorial stations, with water depths of between 3200 and 4600 m, yielded fourteen specific and generic taxonomic groups. Of the taxa analyzed, Uvigerina spp. most closely approaches oxygen isotopic equilibrium with ambient sea water. Pyrgo spp. was next closest to isotopic equilibrium, being on the average 0.59 per thousand depleted in 18 O relative to Uvigerina spp. Oridorsalis umbonatus also has relatively high delta 18 O values. Most other taxa were depleted in 18 O by large amounts. In no taxa was the carbon in the CaCO 3 secreted in carbon isotopic equilibrium with the dissolved HCO 3 - of ambient sea water. (Auth.)

  16. Methanol Droplet Extinction in Oxygen/Carbon-dioxide/Nitrogen Mixtures in Microgravity: Results from the International Space Station Experiments

    Science.gov (United States)

    Nayagam, Vedha; Dietrich, Daniel L.; Ferkul, Paul V.; Hicks, Michael C.; Williams, Forman A.

    2012-01-01

    Motivated by the need to understand the flammability limits of condensed-phase fuels in microgravity, isolated single droplet combustion experiments were carried out in the Combustion Integrated Rack Facility onboard the International Space Station. Experimental observations of methanol droplet combustion and extinction in oxygen/carbon-dioxide/nitrogen mixtures at 0.7 and 1 atmospheric pressure in quiescent microgravity environment are reported for initial droplet diameters varying between 2 mm to 4 mm in this study.The ambient oxygen concentration was systematically lowered from test to test so as to approach the limiting oxygen index (LOI) at fixed ambient pressure. At one atmosphere pressure, ignition and some burning were observed for an oxygen concentration of 13% with the rest being nitrogen. In addition, measured droplet burning rates, flame stand-off ratios, and extinction diameters are presented for varying concentrations of oxygen and diluents. Simplified theoretical models are presented to explain the observed variations in extinction diameter and flame stand-off ratios.

  17. Oxygen-rich hierarchical porous carbon derived from artemia cyst shells with superior electrochemical performance.

    Science.gov (United States)

    Zhao, Yufeng; Ran, Wei; He, Jing; Song, Yanfang; Zhang, Chunming; Xiong, Ding-Bang; Gao, Faming; Wu, Jinsong; Xia, Yongyao

    2015-01-21

    In this study, three-dimensional (3D) hierarchical porous carbon with abundant functional groups is produced through a very simple low-cost carbonization of Artemia cyst shells. The unique hierarchical porous structure of this material, combining large numbers of micropores and macropores, as well as reasonable amount of mesopores, is proven favorable to capacitive behavior. The abundant oxygen functional groups from the natural carbon precursor contribute stable pseudocapacitance. As-prepared sample exhibits high specific capacitance (369 F g(-1) in 1 M H2SO4 and 349 F g(-1) in 6 M KOH), excellent cycling stability with capacitance retention of 100% over 10 000 cycles, and promising rate performance. This work not only describes a simple way to produce high-performance carbon electrode materials for practical application, but also inspires an idea for future structure design of porous carbon.

  18. Oxygen reduction activity of N-doped carbon-based films prepared by pulsed laser deposition

    Science.gov (United States)

    Hakoda, Teruyuki; Yamamoto, Shunya; Kawaguchi, Kazuhiro; Yamaki, Tetsuya; Kobayashi, Tomohiro; Yoshikawa, Masahito

    2010-12-01

    Carbon-based films with nitrogen species on their surface were prepared on a glassy carbon (GC) substrate for application as a non-platinum cathode catalyst for polymer electrolyte fuel cells. Cobalt and carbon were deposited in the presence of N 2 gas using a pulsed laser deposition method and then the metal Co was removed by HCl-washing treatment. Oxygen reduction reaction (ORR) activity was electrochemically determined using a rotating disk electrode system in which the film samples on the GC substrate were replaceable. The ORR activity increased with the temperature of the GC substrate during deposition. A carbon-based film prepared at 600 °C in the presence of N 2 at 66.7 Pa showed the highest ORR activity among the tested samples (0.66 V vs. NHE). This film was composed of amorphous carbons doped with pyridine type nitrogen atoms on its surface.

  19. Electrochemical Reduction of Oxygen on Anthraquinone/Carbon Nanotubes Nanohybrid Modified Glassy Carbon Electrode in Neutral Medium

    Directory of Open Access Journals (Sweden)

    Zheng Gong

    2013-01-01

    Full Text Available The electrochemical behaviors of monohydroxy-anthraquinone/multiwall carbon nanotubes (MHAQ/MWCNTs nanohybrid modified glassy carbon (MHAQ/MWCNTs/GC electrodes in neutral medium were investigated; also reported was their application in the electrocatalysis of oxygen reduction reaction (ORR. The resulting MHAQ/MWCNTs nanohybrid was characterized by scanning electron microscope (SEM and transmission electron microscope (TEM. It was found that the ORR at the MHAQ/MWCNTs/GC electrode occurs irreversibly at a potential about 214 mV less negative than at a bare GC electrode in pH 7.0 buffer solution. Cyclic voltammetric and rotating disk electrode (RDE techniques indicated that the MHAQ/MWCNTs nanohybrid has high electrocatalytic activity for the two-electron reduction of oxygen in the studied potential range. The kinetic parameters of ORR at the MHAQ/MWCNTs nanohybrid modified GC electrode were also determined by RDE and EIS techniques.

  20. Carbon potential measurement on some actinide carbides

    International Nuclear Information System (INIS)

    Anthonysamy, S.; Ananthasivan, K.; Kaliappan, I.; Chandramouli, V.; Vasudeva Rao, P.R.; Mathews, C.K.; Jacob, K.T.

    1994-01-01

    Uranium-Plutonium mixed carbides with a Pu/(U+Pu) ratio of 0.55 are to be used as the fuel in the Fast Breeder Test Reactor (FBTR) at Kalpakkam, India. Carburization of the stainless steel clad by this fuel is determined by its carbon potential. Because the carbon potential of this fuel composition is not available in the literature, it was measured by the methane-hydrogen gas equilibration technique. The sample was equilibrated with purified hydrogen and the equilibrium methane-to-hydrogen ratio in the gas phase was measured with a flame ionization detector. The carbon potential of the ThC-ThC 2 as well as Mo-Mo 2 C system, which is an important binary in the actinide-fission product-carbon systems, were also measured by this technique in the temperature range 973 to 1,173 K. The data for the Mo-Mo 2 C system are in agreement with values reported in the literature. The results for the ThC-ThC 2 system are different from estimated values with large uncertainty limits given in the literature. The data on (U, Pu) mixed carbides indicates the possibility of stainless steel clad attack under isothermal equilibrium conditions

  1. Facultative Stabilization Pond: Measuring Biological Oxygen Demand using Mathematical Approaches

    Science.gov (United States)

    Wira S, Ihsan; Sunarsih, Sunarsih

    2018-02-01

    Pollution is a man-made phenomenon. Some pollutants which discharged directly to the environment could create serious pollution problems. Untreated wastewater will cause contamination and even pollution on the water body. Biological Oxygen Demand (BOD) is the amount of oxygen required for the oxidation by bacteria. The higher the BOD concentration, the greater the organic matter would be. The purpose of this study was to predict the value of BOD contained in wastewater. Mathematical modeling methods were chosen in this study to depict and predict the BOD values contained in facultative wastewater stabilization ponds. Measurements of sampling data were carried out to validate the model. The results of this study indicated that a mathematical approach can be applied to predict the BOD contained in the facultative wastewater stabilization ponds. The model was validated using Absolute Means Error with 10% tolerance limit, and AME for model was 7.38% (< 10%), so the model is valid. Furthermore, a mathematical approach can also be applied to illustrate and predict the contents of wastewater.

  2. Effects of diagenesis on strontium, carbon, nitrogen and oxygen concentration and isotopic composition of bone

    Science.gov (United States)

    Nelson, Bruce K.; Deniro, Michael J.; Schoeninger, Margaret J.; De Paolo, Donald J.; Hare, P. E.

    1986-09-01

    Paleodietary analysis based on variations in the trace element and stable isotopic composition of inorganic and organic phases in fossil bone depends on the assumption that measured values reflect in vivo values. To test for postmortem alteration, we measured 87Sr /86Sr , 13C /12C , 18O /16O and 15N /14N ratios and Sr concentrations in modern and prehistoric (610 to 5470 yr old) bones of animals with marine or terrestrial diets from Greenland. Bones from modern terrestrial feeders have substantially lower Sr concentrations and more radiogenic 87Sr /86Sr ratios than those from modern marine feeders. This contrast was not preserved in the prehistoric samples, which showed almost complete overlap for both Sr concentration and isotopic composition in bones from the two types of animals. Leaching experiments, X-ray diffraction analysis and infrared spectroscopy indicate that alteration of the Sr concentration and isotopic composition in prehistoric bone probably results from nearly complete exchange with groundwater. Oxygen isotope ratios in fossil apatite carbonate also failed to preserve the original discrimination between modern terrestrial and marine feeders. The C isotope ratio of apatite carbonate did not discriminate between animals with marine or terrestrial diets in the modern samples. Even so, the ranges of apatite δ 13C values in prehistoric bone are more scattered than in modern samples for both groups, suggesting alteration had occurred. δ 13C and δ 15N values of collagen in modern bone are distinctly different for the two feeding types, and this distinction is preserved in most of the prehistoric samples. Our results suggest that postmortem alteration of dietary tracers in the inorganic phases of bone may be a problem at all archaeological sites and must be evaluated in each case. While collagen analyzed in this study was resistant to alteration, evaluation of the possibility of diagenetic alteration of its isotopic composition in bones from other

  3. Cerebral oxygenation as measured by near-infrared spectroscopy in neonatal intensive care: correlation with arterial oxygenation.

    Science.gov (United States)

    Hunter, Carol Lu; Oei, Ju Lee; Lui, Kei; Schindler, Timothy

    2017-07-01

    To assess correlation between cerebral oxygenation (rScO 2 ), as measured by near-infrared spectroscopy (NIRS), and arterial oxygenation (PaO 2 ), as measured by arterial blood gases, in preterm neonates. Preterm neonates interpretation of NIRS values in neonatal intensive care, and further evaluation is needed to determine the applicability of NIRS to management of preterm infants. ©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  4. Heteroatom-doped porous carbon from methyl orange dye wastewater for oxygen reduction

    Directory of Open Access Journals (Sweden)

    Yiqing Wang

    2018-04-01

    Full Text Available Banana peel-derived porous carbon (BPPC was prepared from banana peel and used as an adsorbent for methyl orange (MO wastewater removal. BPPC-MO50 is a N,S-doped BPPC obtained via secondary carbonization. The BPPC-MO50 exhibited a high specific surface area of 1774.3 m2/g. Heteroatom-doped porous carbon (PC was successfully synthesized from the BPPC absorbed MO at high temperature and used for oxygen reduction. The BPPC-MO50 displayed the highest ORR onset potential among all carbon-based electrocatalysts, i.e., 0.93 V vs. reversible hydrogen electrode (RHE. This is the first report to describe porous carbon-activated materials from agriculture and forestry waste that is used for adsorption of dyes from wastewater via an enhanced heteroatom (N,S content. These results may contribute to the sustainable development of dye wastewater treatment by transforming saturated PC into an effective material and has potential applications in fuel cells or as energy sources. Keywords: Banana peel, Dye wastewater, Porous carbon, Heteroatom doping, Oxygen reduction reaction

  5. How the oxygen isotope ratio of rain water influences the isotope ratio of chicken eggshell carbonate

    Science.gov (United States)

    Price, Gregory; Grimes, Stephen

    2015-04-01

    The stable oxygen isotope ratio of chicken eggshell carbonate was analysed from chicken eggs laid under free range, and organic farming regimes from across the UK. The eggshell carbonate oxygen isotope data shows a clear depletion in delta18O distribution from the southwest to the northeast. Although consistently offset by around 1 permil, the same isotopic distribution as that seen in eggshell carbonate is observed in the delta18O ratio of rainfall and groundwater from across the UK. This distribution is related to the Rayleigh distillation of rainfall driven by westerly winds across the UK landmass. The clear relationship observed between eggshell delta18O values and that of rainwater presumably reflects the nature of free range chickens which must be drinking locally derived rainwater and supplementing their diet and water intake with locally derived food. These results suggest that the oxygen isotope value of chicken eggshells can be used as a forensic tool to identify the locality that free range and organic eggs were laid within the UK. Furthermore, if suitable material is preserved in the archaeological and geological record then such a relationship can potentially be used to establish the oxygen isotope value of rainwater from which ancient and / or ancestral birds lived.

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

    International Nuclear Information System (INIS)

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

    1999-01-01

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

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

    Science.gov (United States)

    Kim-Hak, D.; Hoffnagle, J.; Rella, C.; Sun, M.

    2016-12-01

    Oxygen is a major and vital component of the Earth atmosphere representing about 21% of its composition. It is consumed or produced through biochemical processes such as combustion, respiration, and photosynthesis. Although atmospheric oxygen is not a greenhouse gas, it can be used as a top-down constraint on the carbon cycle. The variation observations of oxygen in the atmosphere are very small, in the order of the few ppm's. This presents the main technical challenge for measurement as a very high level of precision is required and only few methods including mass spectrometry, fuel cell, and paramagnetic are capable of overcoming it. Here we present new developments of a high-precision gas analyzer that utilizes the technique of Cavity Ring-Down Spectroscopy to measure oxygen concentration and oxygen isotope. Its compact and ruggedness design combined with high precision and long-term stability allows the user to deploy the instrument in the field for continuous monitoring of atmospheric oxygen level. Measurements have a 1-σ 5-minute averaging precision of 1-2 ppm for O2 over a dynamic range of 0-20%. We will present supplemental data acquired from our 10m tower measurements in Santa Clara, CA.

  8. Brain Tissue Oxygen: In Vivo Monitoring with Carbon Paste Electrodes

    Directory of Open Access Journals (Sweden)

    John P. Lowry

    2005-11-01

    Full Text Available In this communication we review selected experiments involving the use ofcarbon paste electrodes (CPEs to monitor and measure brain tissue O2 levels in awakefreely-moving animals. Simultaneous measurements of rCBF were performed using the H2clearance technique. Voltammetric techniques used include both differential pulse (O2 andconstant potential amperometry (rCBF. Mild hypoxia and hyperoxia produced rapidchanges (decrease and increase respectively in the in vivo O2 signal. Neuronal activation(tail pinch and stimulated grooming produced similar increases in both O2 and rCBFindicating that CPE O2 currents provide an index of increases in rCBF when such increasesexceed O2 utilization. Saline injection produced a transient increase in the O2 signal whilechloral hydrate produced slower more long-lasting changes that accompanied the behavioralchanges associated with anaesthesia. Acetazolamide increased O2 levels through an increasein rCBF.

  9. Diiridium Bimetallic Complexes Function as a Redox Switch To Directly Split Carbonate into Carbon Monoxide and Oxygen.

    Science.gov (United States)

    Chen, Tsun-Ren; Wu, Fang-Siou; Lee, Hsiu-Pen; Chen, Kelvin H-C

    2016-03-23

    A pair of diiridium bimetallic complexes exhibit a special type of oxidation-reduction reaction that could directly split carbonate into carbon monoxide and molecular oxygen via a low-energy pathway needing no sacrificial reagent. One of the bimetallic complexes, Ir(III)(μ-Cl)2Ir(III), can catch carbonato group from carbonate and reduce it to CO. The second complex, the rare bimetallic complex Ir(IV)(μ-oxo)2Ir(IV), can react with chlorine to release O2 by the oxidation of oxygen ions with synergistic oxidative effect of iridium ions and chlorine atoms. The activation energy needed for the key reaction is quite low (∼20 kJ/mol), which is far less than the dissociation energy of the C═O bond in CO2 (∼750 kJ/mol). These diiridium bimetallic complexes could be applied as a redox switch to split carbonate or combined with well-known processes in the chemical industry to build up a catalytic system to directly split CO2 into CO and O2.

  10. Effect of Carbon Monoxide on Active Oxygen Metabolism of Postharvest Jujube

    OpenAIRE

    Shaoying Zhang; Qin Li; Yulan Mao

    2014-01-01

    To prolong the shelf life postharvest jujube, the effect of carbon monoxide (CO) on senescence of postharvest jujube in relation to active oxygen metabolism was investigated. Jujubes were fumigated with CO gas at 5, 10, 20 or 40μmol/L for 1 h, and then stored for 30 days at room temperature. Changes in membrane permeability, malonaldehyde (MDA), H2O2, O2•− content, and activities of active oxygen metabolism associated enzymes including superoxide dismutase (SOD), catalase (CAT) and peroxidase...

  11. Carbon and oxygen abundances of field RR Lyrae stars. I. Carbon abundances

    International Nuclear Information System (INIS)

    Butler, D.; Manduca, A.; Deming, D.; Bell, R.A.

    1982-01-01

    From an analysis of KPNO 4-m echelle plates and simultaneous uvbyβ photometry, we have determined carbon abundances and carbon-to-iron ratios for a large number of field RR Lyrae stars having [Fe/H]> or approx. =-1.2. It is found that these field RR Lyrae stars: stars which are known to be in an advanced evolutionary state: have carbon-to-iron ratios which are similar to those of unevolved stars

  12. Adsorption of ionizable organic contaminants on multi-walled carbon nanotubes with different oxygen contents

    International Nuclear Information System (INIS)

    Li Xiaona; Zhao Huimin; Quan Xie; Chen Shuo; Zhang Yaobin; Yu Hongtao

    2011-01-01

    Multi-walled carbon nanotubes (MWNTs), which are considered to be promising candidates for the adsorption of toxic organics, are released into aqueous environment with their increasing production and application. In this study, the adsorption behaviors of five structurally related ionizable organic contaminants namely perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonamide (PFOSA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-n-nonylphenol (4-NP) onto MWNTs with different oxygen contents (3.84-22.85%) were investigated. The adsorption kinetics was investigated and simulated with pseudo-second-order model. The adsorption isotherms were found to be fitted with Freundlich model and influenced by both the properties of organic chemicals and the oxygen contents of MWNTs. As adsorption capacity decreases dramatically with the increasing of oxygen contents, the MWNTs with the lowest oxygen contents possess the highest adsorption capacity among four MWNTs. For the MWNTs with the oxygen contents of 3.84%, the adsorption affinity related with hydrophobic interaction and π-electron polarizability decreased in the order of 4-NP > PFOSA > PFOS > 2,4-D > PFOA. Furthermore, the adsorption characters of five contaminants were affected by solution pH and solute pK a considering electrostatic repulse force and hydrogen bonding, which showed the adsorption of MWNTs with lower oxygen content is much sensitive to solution chemistry.

  13. General and localized corrosion of carbon and low-alloy steels in oxygenated high-temperature water. Final report

    International Nuclear Information System (INIS)

    Macdonald, D.D.; Smialowska, S.; Pednekar, S.

    1983-02-01

    The susceptibilities to stress corrosion cracking (SCC) of two carbon steels, SA106-grB and SA333-gr6, which are used in seamless BWR piping, and a low-alloy pressure vessel steel, A508-C12, were studied in high purity water as a function of oxygen concentration (0.16 to 8 ppM) and temperature (50 to 288 0 C) . The susceptibility to SCC was measured using the slow strain rate technique. The fracture surfaces of the test specimens were also examined using SEM to determine the mode of failure. In water containing 1 and 8 ppM oxygen and at temperatures above 135 0 C, transgranular stress corrosion cracking (TGSCC) was observed to occur in A508-C12, SA333-gr6 and SA106grB steels at very high stresses. The susceptibility to SCC increased with temperature

  14. Carbon-13 and oxygen-18 isotope effects in the decarboxylation of nicotinic acid of natural isotopic composition

    International Nuclear Information System (INIS)

    Zielinski, M.; Zielinska, A.; Papiernik-Zielinska, H.; McKenzie, J.A.; Bernasconi, S.; Paul, H.

    1998-01-01

    Carbon-13 and oxygen-18 isotope effects in the decarboxylation of nicotinic acid of natural isotopic composition above and below its melting temperature have been studied and compared with the primary (PKIE) and secondary kinetic isotope effects (SKIE) of 13 C and 18 O, respectively, in the decarboxylation of other heterocyclic acids. The temperature dependence of the secondary oxygen-18 isotope effects is negative in the total 221-255 deg C temperature interval investigated initially. The 13 C KIE measured above melting point of N.A. (temperature interval 235-270 deg C) are located in the range 1.007-1.009. Below melting point of nicotinic acid the 13 C KIE are larger and reveal the negative temperature dependence ( 13 C KIE decreases with decreasing the reaction temperature from 1.013/at 230 deg C to 1.0114/at 221 deg C). A discussion of the above isotopic results is presented. (author)

  15. Temperature measurements of Transdanubian Mesozoic rocks by the oxygen isotope method

    International Nuclear Information System (INIS)

    Cornides, I.; Csaszar, G.; Haas, J.; Jochane Edelenyi, E.

    1979-01-01

    Subjected to paleotemperature measurements with the use of oxygen and carbon isotopes were Upper Triassic, Jurassic and Cretaceous sedimentary rocks and their fossils from the Transdanubian Central Mountains, the Mecsek and the Villany Mts. In determining formation temperature, an important parameter of the environment of formation, the authors relied on the fact that the oxygen isotope composition of calcium carbonate precipitating from its aqueous solution deviates, in dependence on the temperature of the solution concerned, from that of the water. Consequently, the temperature of the water of the one-time seas must have been recorded by the 18 O/ 16 O ratio in the calcite of fossils or sediments. The results reported indicate smaller changes in temperature as compared to international results. In the Jurassic the values of temperature remain consistently below those quoted for Swiss and French territories, being around the values reported from/sroe/thern Germany. These u curves have their maxima in the Toarcian, Aalenian, sediments for which unfortunately no Hungarian results are available. The few results of Cretaceous belemnites are values higher than their international counterparts. The high temperature value obtained for the Albian correlates very well with the formation of rocks known from this stratigraphic stage (red clays, bauxites). (A.L.)

  16. Radiative muon capture on carbon, oxygen and calcium

    International Nuclear Information System (INIS)

    Armstrong, D.S.; Ahmad, S.; Burnham, R.A.; Gorringe, T.P.; Hasinoff, M.D.; Larabee, A.J.; Waltham, C.E.; Azuelos, G.; Macdonald, J.A.; Numao, T.; Poutissou, J.M.; Clifford, E.T.H.; Summhammer, J.; Blecher, M.; Wright, D.H.; Depommier, P.; Poutissou, R.; Mes, H.; Robertson, B.C.

    1990-05-01

    The photon energy spectra from radiative muon capture on 12 C, 16 O and 40 Ca have been measured using a time projection chamber as a pair spectrometer. The branching ratio for radiative muon capture is sensitive to g p , the induced pseudoscalar coupling constant of the weak interaction. Expressed in terms of the axial-vector weak coupling constant g a , values of g p /g a = 5.7 ± 0.8 and g p /g a = 7.3 ± 0.9 are obtained for 40 Ca and 16 O respectively, from comparison with phenomenological calculations of the nuclear response. From comparison with microscopic calculations, values of g p /g a = 4.6 ± 1.8, 13.6 +1.6 -1.9 and 16.2 +1.3 -0.7 for 40 Ca, 16 O and 12 C, respectively, are obtained. The microscopic results are suggestive of a renormalization of the nucleonic form factors within the nucleus. (Author) (78 refs., 14 tabs, 22 figs.)

  17. Manual or automated measuring of antipsychotics' chemical oxygen demand.

    Science.gov (United States)

    Pereira, Sarah A P; Costa, Susana P F; Cunha, Edite; Passos, Marieta L C; Araújo, André R S T; Saraiva, M Lúcia M F S

    2018-05-15

    Antipsychotic (AP) drugs are becoming accumulated in terrestrial and aqueous resources due to their actual consumption. Thus, the search of methods for assessing the contamination load of these drugs is mandatory. The COD is a key parameter used for monitoring water quality upon the assessment of the effect of polluting agents on the oxygen level. Thus, the present work aims to assess the chemical oxygen demand (COD) levels of several typical and atypical antipsychotic drugs in order to obtain structure-activity relationships. It was implemented the titrimetric method with potassium dichromate as oxidant and a digestion step of 2h, followed by the measurement of remained unreduced dichromate by titration. After that, an automated sequential injection analysis (SIA) method was, also, used aiming to overcome some drawbacks of the titrimetric method. The results obtained showed a relationship between the chemical structures of antipsychotic drugs and their COD values, where the presence of aromatic rings and oxidable groups give higher COD values. It was obtained a good compliance between the results of the reference batch procedure and the SIA system, and the APs were clustered in two groups, with the values ratio between the methodologies, of 2 or 4, in the case of lower or higher COD values, respectively. The SIA methodology is capable of operating as a screening method, in any stage of a synthetic process, being also more environmentally friendly, and cost-effective. Besides, the studies presented open promising perspectives for the improvement of the effectiveness of pharmaceutical removal from the waste effluents, by assessing COD values. Copyright © 2018 Elsevier Inc. All rights reserved.

  18. Polypyrrole/Co-tetraphenylporphyrin modified carbon fibre paper as a fuel cell electrocatalyst of oxygen reduction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Weimin; Chen, Jun; Wagner, Pawel; Wallace, Gordon G. [ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong NSW 2522 (Australia); Swiegers, Gerhard F. [CSIRO Molecular and Health Technologies, Bag 10, Clayton VIC 3169 (Australia)

    2008-04-15

    A thin-layer of polypyrrole (PPy) film, immobilized with neutral 5,10,15,20-tetraphenylporphyrinato cobalt (II) (Co-TPP), was successfully and uniformly deposited onto mesoporous carbon fibre paper (CFP) via vapor-phase polymerization. The resulting PPy/Co-TPP-modified carbon fibre paper (PPy/Co-TPP-CFP) electrode was characterized by cyclic voltammetry, SEM and EDX-ray mapping. Its electrochemical stability and long-term electrocatalytic performance were investigated in a half-fuel cell testing system. The electrode displayed significant electrocatalytic performance for oxygen reduction at 0.0 V (vs. Ag/AgCl), with notable long-term stability. (author)

  19. Measuring and predicting sooting tendencies of oxygenates, alkanes, alkenes, cycloalkanes, and aromatics on a unified scale

    Energy Technology Data Exchange (ETDEWEB)

    Das, Dhrubajyoti D.; St. John, Peter C.; McEnally, Charles S.; Kim, Seonah; Pfefferle, Lisa D.

    2018-04-01

    Databases of sooting indices, based on measuring some aspect of sooting behavior in a standardized combustion environment, are useful in providing information on the comparative sooting tendencies of different fuels or pure compounds. However, newer biofuels have varied chemical structures including both aromatic and oxygenated functional groups, which expands the chemical space of relevant compounds. In this work, we propose a unified sooting tendency database for pure compounds, including both regular and oxygenated hydrocarbons, which is based on combining two disparate databases of yield-based sooting tendency measurements in the literature. Unification of the different databases was made possible by leveraging the greater dynamic range of the color ratio pyrometry soot diagnostic. This unified database contains a substantial number of pure compounds (greater than or equal to 400 total) from multiple categories of hydrocarbons important in modern fuels and establishes the sooting tendencies of aromatic and oxygenated hydrocarbons on the same numeric scale for the first time. Using this unified sooting tendency database, we have developed a predictive model for sooting behavior applicable to a broad range of hydrocarbons and oxygenated hydrocarbons. The model decomposes each compound into single-carbon fragments and assigns a sooting tendency contribution to each fragment based on regression against the unified database. The model's predictive accuracy (as demonstrated by leave-one-out cross-validation) is comparable to a previously developed, more detailed predictive model. The fitted model provides insight into the effects of chemical structure on soot formation, and cases where its predictions fail reveal the presence of more complicated kinetic sooting mechanisms. This work will therefore enable the rational design of low-sooting fuel blends from a wide range of feedstocks and chemical functionalities.

  20. Recycling of rare earth magnet scraps: Carbon and oxygen removal from Nd magnet scraps

    International Nuclear Information System (INIS)

    Saguchi, A.; Asabe, K.; Fukuda, T.; Takahashi, W.; Suzuki, R.O.

    2006-01-01

    The decarburization and deoxidation technique for permanent Nd-Fe-B magnet scrap is investigated. The carbon and oxygen contamination damage the magnetic properties. The carbon content decreased less than 0.001% by heating in air. The two stage deoxidation is applied, iron oxides are reduced by heating in hydrogen thereafter rare earth oxides are removed by Ca-reduction and leaching. The appropriate conditions for deoxidation in the Ca-reduction and suppressing the re-oxidation in the leaching are investigated. The heating pattern in Ca-reduction and the leaching condition for the mixture composed of Ca compounds and Nd-Fe-B alloy powder greatly affects the oxygen content of recycled material. The decarburized and deoxidized Nd-Fe-B magnet scrap can be recycled as alloying elements by melting

  1. Influences of Air, Oxygen, Nitrogen, and Carbon Dioxide Nanobubbles on Seed Germination and Plant Growth.

    Science.gov (United States)

    Ahmed, Ahmed Khaled Abdella; Shi, Xiaonan; Hua, Likun; Manzueta, Leidy; Qing, Weihua; Marhaba, Taha; Zhang, Wen

    2018-05-23

    Nanobubbles (NBs) hold promise in green and sustainable engineering applications in diverse fields (e.g., water/wastewater treatment, food processing, medical applications, and agriculture). This study investigated the effects of four types of NBs on seed germination and plant growth. Air, oxygen, nitrogen, and carbon dioxide NBs were generated and dispersed in tap water. Different plants, including lettuce, carrot, fava bean, and tomato, were used in germination and growth tests. The seeds in water-containing NBs exhibited 6-25% higher germination rates. Especially, nitrogen NBs exhibited considerable effects in the seed germination, whereas air and carbon dioxide NBs did not significantly promote germination. The growth of stem length and diameter, leave number, and leave width were promoted by NBs (except air). Furthermore, the promotion effect was primarily ascribed to the generation of exogenous reactive oxygen species by NBs and higher efficiency of nutrient fixation or utilization.

  2. Modification of pure oxygen absorption equipment for concurrent stripping of carbon dioxide

    Science.gov (United States)

    Watten, B.J.; Sibrell, P.L.; Montgomery, G.A.; Tsukuda, S.M.

    2004-01-01

    The high solubility of carbon dioxide precludes significant desorption within commercial oxygen absorption equipment. This operating characteristic of the equipment limits its application in recirculating water culture systems despite its ability to significantly increase allowable fish loading rates (kg/(L min)). Carbon dioxide (DC) is typically removed by air stripping. This process requires a significant energy input for forced air movement, air heating in cold climates and water pumping. We developed a modification for a spray tower that provides for carbon dioxide desorption as well as oxygen absorption. Elimination of the air-stripping step reduces pumping costs while allowing dissolved nitrogen to drop below saturation concentrations. This latter response provides for an improvement in oxygen absorption efficiency within the spray tower. DC desorption is achieved by directing head-space gases from the spray tower (O2, N2, CO2) through a sealed packed tower scrubber receiving a 2 N NaOH solution. Carbon dioxide is selectively removed from the gas stream, by chemical reaction, forming the product Na 2CO3. Scrubber off-gas, lean with regard to carbon dioxide but still rich with oxygen, is redirected through the spray tower for further stripping of DC and absorption of oxygen. Make-up NaOH is metered into the scrubbing solution sump on an as needed basis as directed by a feedback control loop programmed to maintain a scrubbing solution pH of 11.4-11.8. The spent NaOH solution is collected, then regenerated for reuse, in a batch process that requires relatively inexpensive hydrated lime (Ca(OH)2). A by-product of the regeneration step is an alkaline filter cake, which may have use in bio-solids stabilization. Given the enhanced gas transfer rates possible with chemical reaction, the required NaOH solution flow rate through the scrubber represents a fraction of the spray tower water flow rate. Further, isolation of the water being treated from the atmosphere (1

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-08-03

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

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  5. Collisions of carbon and oxygen ions with electrons, H, H2 and He: Volume 5

    International Nuclear Information System (INIS)

    Phaneuf, R.A.; Janev, R.K.; Pindzola, M.S.

    1987-02-01

    This report provides a handbook for fusion research of recommended cross-section and rate-coefficient data for collisions of carbon and oxygen ions with electrons, hydrogen atoms and molecules, and helium atoms. Published experimental and theoretical data have been collected and evaluated, and recommended data are presented in tabular, graphical, and parametrized form. Processes considered include exciation, ionization, and charge exchange at collision energies appropriate to applications in fusion-energy research

  6. Investigation of lithium forward scattering for the analysis of carbon and oxygen in human amniotic fluid

    International Nuclear Information System (INIS)

    Liendo, J.A.; Instituto Venezolano de Investigaciones Cientificas, Caracas; Florida State University, Tallahasse, FL; Gonzalez, A.C.; Rojas, A.; Instituto Venezolano de Investigaciones Cientificas, Caracas; Fletcher, N.R.; Caussyn, D.D.; Barber, P.

    2006-01-01

    Lithium forward elastic scattering is investigated as an additional method for Z 6,7 Li beams and the elastically scattered beam is detected at 16.45 deg, 20.45 deg and 28.0 deg simultaneously. The quality of elastic spectra improves with sample dilution. The content of C and O in the backing is subtracted. Carbon and oxygen concentrations of the non-diluted AF sample are determined by assuming that elemental concentration varies linearly with dilution. (author)

  7. A universal carbonate ion effect on stable oxygen isotope ratios in unicellular planktonic calcifying organisms

    OpenAIRE

    Ziveri, P.; Thoms, S.; Probert, I.; Geisen, M.; Langer, H.

    2012-01-01

    The oxygen isotopic composition (δ18O) of calcium carbonate of planktonic calcifying organisms is a key tool for reconstructing both past seawater temperature and salinity. The calibration of paloeceanographic proxies relies in general on empirical relationships derived from field experiments on extant species. Laboratory experiments have more often than not revealed that variables other than the target parameter influence the proxy signal, which makes proxy c...

  8. Bio-inspired carbon electro-catalysis for the oxygen reduction reaction

    OpenAIRE

    Preuss, Kathrin; Kannuchamy, Vasanth Kumar; Marinovic, Adam; Isaacs, Mark; Wilson, Karen; Abrahams, Isaac; Titirici, Maria-Magdalena

    2016-01-01

    We report the synthesis, characterisation and catalytic performance of two nature-inspired biomass-derived electro-catalysts for the oxygen reduction reaction in fuel cells. The catalysts were prepared via pyrolysis of a real food waste (lobster shells) or by mimicking the composition of lobster shells using chitin and CaCO3 particles followed by acid washing. The simplified model of artificial lobster was prepared for better reproducibility. The calcium carbonate in both samples acts as a po...

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

    DEFF Research Database (Denmark)

    Qingfeng, Li; Hjuler, Hans Aage; Bjerrum, Niels

    2000-01-01

    Oxygen reduction on carbon supported platinum catalysts has been investigated in H3PO4, H3PO4-doped Nafion and polybenzimidazole (PBI) polymer electrolytes in a temperature range up to 190 degrees C. Compared with pure H3PO4, the combination of H3PO4 and polymer electrolytes can significantly...... membrane fuel cell based on H3PO4-doped PBI for operation at temperatures between 150 and 200 degrees C. (C) 2000 Elsevier Science Ltd. All rights reserved....

  10. Silicon solar cell performance deposited by diamond like carbon thin film ;Atomic oxygen effects;

    Science.gov (United States)

    Aghaei, Abbas Ail; Eshaghi, Akbar; Karami, Esmaeil

    2017-09-01

    In this research, a diamond-like carbon thin film was deposited on p-type polycrystalline silicon solar cell via plasma-enhanced chemical vapor deposition method by using methane and hydrogen gases. The effect of atomic oxygen on the functioning of silicon coated DLC thin film and silicon was investigated. Raman spectroscopy, field emission scanning electron microscopy, atomic force microscopy and attenuated total reflection-Fourier transform infrared spectroscopy were used to characterize the structure and morphology of the DLC thin film. Photocurrent-voltage characteristics of the silicon solar cell were carried out using a solar simulator. The results showed that atomic oxygen exposure induced the including oxidation, structural changes, cross-linking reactions and bond breaking of the DLC film; thus reducing the optical properties. The photocurrent-voltage characteristics showed that although the properties of the fabricated thin film were decreased after being exposed to destructive rays, when compared with solar cell without any coating, it could protect it in atomic oxygen condition enhancing solar cell efficiency up to 12%. Thus, it can be said that diamond-like carbon thin layer protect the solar cell against atomic oxygen exposure.

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

    Science.gov (United States)

    Lv, Lin; Zha, Dace; Ruan, Yunjun; Li, Zhishan; Ao, Xiang; Zheng, Jie; Jiang, Jianjun; Chen, Hao Ming; Chiang, Wei-Hung; Chen, Jun; Wang, Chundong

    2018-03-27

    Oxygen is the most abundant element in the Earth's crust. The oxygen reduction reaction (ORR) is also the most important reaction in life processes and energy converting/storage systems. Developing techniques toward high-efficiency ORR remains highly desired and a challenge. Here, we report a N-doped carbon (NC) encapsulated CeO 2 /Co interfacial hollow structure (CeO 2 -Co-NC) via a generalized strategy for largely increased oxygen species adsorption and improved ORR activities. First, the metallic Co nanoparticles not only provide high conductivity but also serve as electron donors to largely create oxygen vacancies in CeO 2 . Second, the outer carbon layer can effectively protect cobalt from oxidation and dissociation in alkaline media and as well imparts its higher ORR activity. In the meanwhile, the electronic interactions between CeO 2 and Co in the CeO 2 /Co interface are unveiled theoretically by density functional theory calculations to justify the increased oxygen absorption for ORR activity improvement. The reported CeO 2 -Co-NC hollow nanospheres not only exhibit decent ORR performance with a high onset potential (922 mV vs RHE), half-wave potential (797 mV vs RHE), and small Tafel slope (60 mV dec -1 ) comparable to those of the state-of-the-art Pt/C catalysts but also possess long-term stability with a negative shift of only 7 mV of the half-wave potential after 2000 cycles and strong tolerance against methanol. This work represents a solid step toward high-efficient oxygen reduction.

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

    Science.gov (United States)

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

    2017-07-01

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

  13. Noncovalently functionalized graphitic mesoporous carbon as a stable support of Pt nanoparticles for oxygen reduction

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Yuyan; Zhang, Sheng; Kou, Rong; Wang, Chongmin; Viswanathan, Vilayanur; Liu, Jun; Wang, Yong; Lin, Yuehe [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Wang, Xiqing; Dai, Sheng [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2010-04-02

    We report a durable electrocatalyst support, highly graphitized mesoporous carbon (GMPC), for oxygen reduction in polymer electrolyte membrane (PEM) fuel cells. GMPC is prepared through graphitizing the self-assembled soft-template mesoporous carbon (MPC) under high temperature. Heat-treatment at 2800 C greatly improves the degree of graphitization while most of the mesoporous structures and the specific surface area of MPC are retained. GMPC is then noncovalently functionalized with poly(diallyldimethylammonium chloride) (PDDA) and loaded with Pt nanoparticles by reducing Pt precursor (H{sub 2}PtCl{sub 6}) in ethylene glycol. Pt nanoparticles of {proportional_to}3.0 nm in diameter are uniformly dispersed on GMPC. Compared to Pt supported on Vulcan XC-72 carbon black (Pt/XC-72), Pt/GMPC exhibits a higher mass activity towards oxygen reduction reaction (ORR) and the mass activity retention (in percentage) is improved by a factor of {proportional_to}2 after 44 h accelerated degradation test under the potential step (1.4-0.85 V) electrochemical stressing condition which focuses on support corrosion. The enhanced activity and durability of Pt/GMPC are attributed to the graphitic structure of GMPC which is more resistant to corrosion. These findings demonstrate that GMPC is a promising oxygen reduction electrocatalyst support for PEM fuel cells. The approach reported in this work provides a facile, eco-friendly promising strategy for synthesizing stable metal nanoparticles on hydrophobic support materials. (author)

  14. Separation of krypton from carbon dioxide and oxygen with molecular sieves

    International Nuclear Information System (INIS)

    Forsberg, C.W.

    1976-01-01

    Molecular sieves were investigated to separate 1 percent mixtures of krypton in gas streams of a few percent oxygen and 90+ percent carbon dioxide. Such a system will be required to concentrate the krypton gas between radioactive krypton off-gas cleanup systems such as KALC (Krypton Absorption in Liquid Carbon Dioxide) and any krypton gas bottling station. Linde 5A molecular sieves were found capable of selectively removing the CO 2 from the gas stream while partially separating the oxygen from the krypton; i.e., effecting a three-component gas separation. This use of molecular sieves differs from standard practice in two respects. First, the bulk of the gas (greater than 90 percent) is removed by molecular sieves rather than the normal practice of using molecular sieves to remove trace impurities. Second, in a single bed two separations occur simultaneously, CO 2 from other gases and krypton from oxygen. The use of molecular sieves for separating krypton and carbon dioxide is superior to alternatives such as CO 2 freezeout and chemical traps when there are only moderate gas flows and there is a need for very high reliability and ease of maintenance

  15. Non-elastic cross-sections for neutron interactions with carbon and oxygen above 14 MeV

    International Nuclear Information System (INIS)

    Brenner, D.J.; Prael, R.E.

    1985-01-01

    In the light of the new generation of high energy (less than or equal to 80 MeV) neutron therapy facilities currently being tested, the need for neutron kerma factors in the range from 15 to 80 MeV on carbon and oxygen has become of urgent importance. Not enough experimental data currently exist or are likely to be measured soon, so a nuclear model is essential for interpolation or, less satisfactorily, extrapolation of available data. The use of a suitable model, applicable to light nuclei, is shown to be crucial. Such a model is described, and good agreement between its results and the experimental data in the energy range of interest is reported. Comparisons between the model predictions and the ENDF/B-V evaluation of the non-elastic cross section for carbon between 15 and 20 MeV indicate that a re-evaluation of ENDF is required. 35 refs., 12 figs., 6 tabs

  16. Effect of carbon on the oxidation of zirconium; Influence du carbone sur l'oxygenation du zirconium a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Chauvin, G; Boudouresques, B; Coriou, H; Hure, J [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    The study of specimens contaminated by different amounts of carbon shows a deleterious effect of this element in the resistance of zirconium to high temperature oxidation (700 to 900 deg. C). We drew the following results: a) the white spots or 'pimples' observed by numerous authors seem to be caused by the oxidation of precipitated carbides. We suggest a mechanism of formation and growth of these pimples; b) for a certain carbon content, the resistance to oxidation is increased by an uniform dispersion of the carbide phase and decreased, for instance, by extrusion textures. In this case, for the more marked textures, the more oriented corrosion was observed; c) by burning of the carbide phase it can result a second reaction increasing the corrosion rate; d) thin zirconium foils undergoes dimensional changes when scaling in oxygen. This unusual feature is also subordinated to carbon content and specially to the carbide phase dispersion. (author) [French] L'etude d'echantillons differemment contamines par le carbone nous a permis de mettre en evidence l'action particulierement nocive de cet element sur la resistance du zirconium a la corrosion par l'oxygene a haute temperature (700 a 900 deg. C). Nous avons pu degager les resultats essentiels suivants: a) l'origine des pustules d'oxyde blanc signalees par de nombreux auteurs doit etre recherchee dans l'oxydation des carbures precipites. Nous suggerons un mecanisme de formation et de croissance de ces pustules, b) la tenue du metal est d'autant meilleure que, pour une meme teneur en carbone, la phase 'carbure' est plus uniformement dispersee. En consequence, si la dispersion est mauvaise, on observe selon l'axe des textures de filage, par exemple, une corrosion preferentielle d'autant plus accentuee que les textures sont plus marquees, c) la combustion de la phase 'carbure' peut engendrer une reaction secondaire susceptible d'accroitre la cinetique de corrosion, d) l'expansion des grandes faces d

  17. Controllable synthesis of mesoporous carbon nanospheres and Fe-N/carbon nanospheres as efficient oxygen reduction electrocatalysts

    Science.gov (United States)

    Wei, Jing; Liang, Yan; Zhang, Xinyi; Simon, George P.; Zhao, Dongyuan; Zhang, Jin; Jiang, Sanping; Wang, Huanting

    2015-03-01

    The synthesis of mesoporous carbon nanospheres (MCNs), especially with diameters below 200 nm remains a great challenge due to weak interactions between the carbon precursors and soft templates, as well as the uncontrollable cross-linking rate of carbon precursors. Herein, we demonstrate a simple acid-assisted, hydrothermal synthesis approach to synthesizing such uniform MCNs with well controlled diameters ranging from 20 to 150 nm under highly acidic conditions (2 M HCl). Both the carbon precursor and the template are partly protonated under such conditions and show additional Coulombic interactions with chloride ions (acts as mediators). This kind of enhanced interaction is similar to that of the ``I+X-S+'' mechanism in the synthesis of mesoporous metal oxide, which can effectively retard the cross-linking rate of resol molecules and avoid macroscopic phase separation during the hydrothermal synthesis. Due to their uniform spherical morphology, small diameter, and high surface areas, MCNs can be modified with Fe and N species via impregnation of cheap precursors (ferric nitrate and dicyandiamide), which are further converted into nonprecious electrocatalysts for oxygen reduction reactions. The resulting Fe-N/MCNs exhibit high catalytic activities, long-term stability and improved methanol tolerance under alkaline conditions, which can be potentially used in direct methanol fuel cells and metal-air batteries.The synthesis of mesoporous carbon nanospheres (MCNs), especially with diameters below 200 nm remains a great challenge due to weak interactions between the carbon precursors and soft templates, as well as the uncontrollable cross-linking rate of carbon precursors. Herein, we demonstrate a simple acid-assisted, hydrothermal synthesis approach to synthesizing such uniform MCNs with well controlled diameters ranging from 20 to 150 nm under highly acidic conditions (2 M HCl). Both the carbon precursor and the template are partly protonated under such conditions

  18. The Rise of Oxygen in the Earth's Atmosphere Controlled by the Efficient Subduction of Organic Carbon

    Science.gov (United States)

    Duncan, M. S.; Dasgupta, R.

    2017-12-01

    Carbon cycling between the Earth's surface environment, i.e., the ocean-atmosphere system, and the Earth's interior is critical for differentiation, redox evolution, and long-term habitability of the planet. This carbon cycle is influenced heavily by the extent of carbon subduction. While the fate of carbonates during subduction has been discussed in numerous studies [e.g., 1], little is known how organic carbon is quantitatively transferred from the Earth's surface to the interior. Efficient subduction of organic carbon would remove reduced carbon from the surface environment over the long-term (≥100s Myrs) while release at subduction zone arc volcanoes would result in degassing of CO2. Here we conducted high pressure-temperature experiments to determine the carbon carrying capacity of slab derived, rhyolitic melts under graphite-saturated conditions over a range of P (1.5-3.0 GPa) and T (1100-1400 °C) at a fixed melt H2O content (2 wt.%) [2]. Based on our experimental data, we developed a thermodynamic model of CO2 dissolution in C-saturated slab melts, that allows us to quantify the extent of organic carbon mobility as a function of slab P, T, and fO2 during subduction through time. Our experimental data and thermodynamic model suggest that the subduction of graphitized organic C, and graphite/diamond formed by reduction of carbonates with depth [e.g., 3], remained efficient even in ancient, hotter subduction zones - conditions at which subduction of carbonates likely remained limited [1]. Considering the efficiency the subduction of organic C and potential conditions for ancient subduction, we suggest that the lack of remobilization in subduction zones and deep sequestration of organic C in the mantle facilitated the rise and maintenance atmospheric oxygen in the Paleoproterozoic and is causally linked to the Great Oxidation Event (GOE). Our modeling shows that episodic subduction and organic C sequestration pre-GOE may also explain occasional whiffs of

  19. Oxygen Transport Membrane Reactors for Oxy-Fuel Combustion and Carbon Capture Purposes

    Science.gov (United States)

    Falkenstein-Smith, Ryan L.

    research show that under a wide range of membrane temperatures and in a variety of atmospheres, a pure SSC OTM can achieve superior surface exchange and oxygen chemical diffusion coefficients compared to other commonly studied materials. SSC's high oxygen permeability (>1 ml.min -1.cm-2) demonstrates the material's candidacy for the application of oxy-fuel combustion. However, in the presence of rich CO 2 atmospheres, SSC shows mechanical and chemical instabilities due to the carbonate formation on the perovskite structure. The addition of SDC in the membrane composition produces a dual-phase OTM which is observed to improve the oxygen permeation flux when subjected to pure CO2 sweeping gases. When subjected to pure methane sweeping gases, dual-phase OTM compositions exhibits lower oxygen permeability compared to the single-phase SSC OTM. Despite the decline in the oxygen permeation flux, some dual-phase compositions still exhibit a high oxygen permeability, indicating their potential for the application of oxy-fuel combustion. Furthermore, a newly developed method for evaluating OTMs for the application of oxy-fuel combustion is presented in a portion of this work. This new method calculates key components such as the average oxygen permeation flux, approximate effective surface area, and the impact of additional recirculated exhaust into the incoming sweeping gas to provide a detailed understanding of OTM's application for oxy-fuel combustion. The development of this approach will aid in the evaluation of newly developed materials and create a new standard for implementing OTMs for the application of oxy-fuel combustion.

  20. Could a secular increase in organic burial explain the rise of oxygen? Insights from a geological carbon cycle model constrained by the carbon isotope record

    Science.gov (United States)

    Krissansen-Totton, J.; Kipp, M.; Catling, D. C.

    2017-12-01

    The stable isotopes of carbon in marine sedimentary rock provide a window into the evolution of the Earth system. Conventionally, a relatively constant carbon isotope ratio in marine sedimentary rocks has been interpreted as implying constant organic carbon burial relative to total carbon burial. Because organic carbon burial corresponds to net oxygen production from photosynthesis, it follows that secular changes in the oxygen source flux cannot explain the dramatic rise of oxygen over Earth history. Instead, secular declines in oxygen sink fluxes are often invoked as causes for the rise of oxygen. However, constant fractional organic burial is difficult to reconcile with tentative evidence for low phosphate concentrations in the Archean ocean, which would imply lower marine productivity and—all else being equal—less organic carbon burial than today. The conventional interpretation of the carbon isotope record rests on the untested assumption that the isotopic ratio of carbon inputs into the ocean reflect mantle isotopic values throughout Earth history. In practice, differing rates of carbonate and organic weathering will allow for changes in isotopic inputs, as suggested by [1] and [2]. However, these inputs can not vary freely because large changes in isotopic inputs would induce secular trends in carbon reservoirs, which are not observed in the isotope record. We apply a geological carbon cycle model to all Earth history, tracking carbon isotopes in crustal, mantle, and ocean reservoirs. Our model is constrained by the carbon isotope record such that we can determine the extent to which large changes in organic burial are permitted. We find both constant organic burial and 3-5 fold increases in organic burial since 4.0 Ga can be reconciled with the carbon isotope record. Changes in the oxygen source flux thus need to be reconsidered as a possible contributor to Earth's oxygenation. [1] L. A. Derry, Organic carbon cycling and the lithosphere, in Treatise on

  1. Method for obtaining more precise measures of excreted organic carbon

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    A new method for concentrating and measuring excreted organic carbon by lyophilization and scintillation counting is efficient, improves measurable radioactivity, and increases precision for estimates of organic carbon excreted by phytoplankton and macrophytes

  2. Effects of Changes in Arterial Carbon Dioxide and Oxygen Partial Pressures on Cerebral Oximeter Performance.

    Science.gov (United States)

    Schober, Andrew; Feiner, John R; Bickler, Philip E; Rollins, Mark D

    2018-01-01

    Cerebral oximetry (cerebral oxygen saturation; ScO2) is used to noninvasively monitor cerebral oxygenation. ScO2 readings are based on the fraction of reduced and oxidized hemoglobin as an indirect estimate of brain tissue oxygenation and assume a static ratio of arterial to venous intracranial blood. Conditions that alter cerebral blood flow, such as acute changes in PaCO2, may decrease accuracy. We assessed the performance of two commercial cerebral oximeters across a range of oxygen concentrations during normocapnia and hypocapnia. Casmed FORE-SIGHT Elite (CAS Medical Systems, Inc., USA) and Covidien INVOS 5100C (Covidien, USA) oximeter sensors were placed on 12 healthy volunteers. The fractional inspired oxygen tension was varied to achieve seven steady-state levels including hypoxic and hyperoxic PaO2 values. ScO2 and simultaneous arterial and jugular venous blood gas measurements were obtained with both normocapnia and hypocapnia. Oximeter bias was calculated as the difference between the ScO2 and reference saturation using manufacturer-specified weighting ratios from the arterial and venous samples. FORE-SIGHT Elite bias was greater during hypocapnia as compared with normocapnia (4 ± 9% vs. 0 ± 6%; P oxygen saturation and mixed venous oxygen tension, as well as increased oxygen extraction across fractional inspired oxygen tension levels (P oxygen extraction (P < 0.0001). Changes in PaCO2 affect cerebral oximeter accuracy, and increased bias occurs with hypocapnia. Decreased accuracy may represent an incorrect assumption of a static arterial-venous blood fraction. Understanding cerebral oximetry limitations is especially important in patients at risk for hypoxia-induced brain injury, where PaCO2 may be purposefully altered.

  3. 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.

  4. Anomalous cosmic ray carbon and oxygen tracks in CN-Kodak.

    Science.gov (United States)

    Kondratyeva, M A; Tretyakova, C A; Tretyakova, S P; Zhuravlev, D A

    2001-06-01

    For observation of low energy cosmic ray particles we used CN-Kodak nuclear track detectors on Cosmos satellites. In solar quiet periods during solar minima conditions the detectors registered anomalous cosmic rays (ACRs). The ACRs are characterized by flux enhancements of several elements and it is known that the carbon enhancement is small compared with that of oxygen. In all of our quiet-time exposures the relation between carbon and oxygen was extremely small (C/O ~ 0.03). But in two quiet-time periods of 14.03.96-11.06.96 and of 15.12.97-14.04.98 we have identified many tracks as carbon in a L-R diagram. As a result the observed C/O ratio appears to be more than 0.5, whereas other experiments show no evidence of enhanced flux of carbon during these periods. The reason for the unexpected response of CN-Kodak is discussed. c2001 Elsevier Science Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2017-10-01

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

  6. ASRDI oxygen technology survey. Volume 5: Density and liquid level measurement instrumentation for the cryogenic fluids oxygen, hydrogen, and nitrogen

    Science.gov (United States)

    Roder, H. M.

    1974-01-01

    Information is presented on instrumentation for density measurement, liquid level measurement, quantity gauging, and phase measurement. Coverage of existing information directly concerned with oxygen was given primary emphasis. A description of the physical principle of measurement for each instrumentation type is included. The basic materials of construction are listed if available from the source document for each instrument discussed. Cleaning requirements, procedures, and verification techniques are included.

  7. Nitrogen-doped carbon-supported cobalt-iron oxygen reduction catalyst

    Science.gov (United States)

    Zelenay, Piotr; Wu, Gang

    2014-04-29

    A Fe--Co hybrid catalyst for oxygen reaction reduction was prepared by a two part process. The first part involves reacting an ethyleneamine with a cobalt-containing precursor to form a cobalt-containing complex, combining the cobalt-containing complex with an electroconductive carbon supporting material, heating the cobalt-containing complex and carbon supporting material under conditions suitable to convert the cobalt-containing complex and carbon supporting material into a cobalt-containing catalyst support. The second part of the process involves polymerizing an aniline in the presence of said cobalt-containing catalyst support and an iron-containing compound under conditions suitable to form a supported, cobalt-containing, iron-bound polyaniline species, and subjecting said supported, cobalt-containing, iron bound polyaniline species to conditions suitable for producing a Fe--Co hybrid catalyst.

  8. Nitrogen-Doped Carbon Nanotube and Graphene Materials for Oxygen Reduction Reactions

    Directory of Open Access Journals (Sweden)

    Qiliang Wei

    2015-09-01

    Full Text Available Nitrogen-doped carbon materials, including nitrogen-doped carbon nanotubes (NCNTs and nitrogen-doped graphene (NG, have attracted increasing attention for oxygen reduction reaction (ORR in metal-air batteries and fuel cell applications, due to their optimal properties including excellent electronic conductivity, 4e− transfer and superb mechanical properties. Here, the recent progress of NCNTs- and NG-based catalysts for ORR is reviewed. Firstly, the general preparation routes of these two N-doped carbon-allotropes are introduced briefly, and then a special emphasis is placed on the developments of both NCNTs and NG as promising metal-free catalysts and/or catalyst support materials for ORR. All these efficient ORR electrocatalysts feature a low cost, high durability and excellent performance, and are thus the key factors in accelerating the widespread commercialization of metal-air battery and fuel cell technologies.

  9. Influence of Chemical and Physical Properties of Activated Carbon Powders on Oxygen Reduction and Microbial Fuel Cell Performance

    KAUST Repository

    Watson, Valerie J.; Nieto Delgado, Cesar; Logan, Bruce E.

    2013-01-01

    Commercially available activated carbon (AC) powders made from different precursor materials (coal, peat, coconut shell, hardwood, and phenolic resin) were electrochemically evaluated as oxygen reduction catalysts and tested as cathode catalysts

  10. Biological Apatite Formed from Polyphosphate and Alkaline Phosphatase May Exchange Oxygen Isotopes from Water through Carbonate

    Science.gov (United States)

    Omelon, S. J.; Stanley, S. Y.; Gorelikov, I.; Matsuura, N.

    2011-12-01

    The oxygen isotopic composition in bone mineral phosphate is known to reflect the local water composition, environmental humidity, and diet1. Once ingested, biochemical processes presumably equilibrate PO43- with "body water" by the many biochemical reactions involving PO43- 2. Blake et al. demonstrated that enzymatic release of PO43- from organophosphorus compounds, and microbial metabolism of dissolved orthophosphate, significantly exchange the oxygen in precipitated apatite within environmental water3,4, which otherwise does not exchange with water at low temperatures. One of the enzymes that can cleave phosphates from organic substrates is alkaline phosphastase5, the enzyme also associated with bone mineralization. The literature often states that the mineral in bone in hydroxylapatite, however the mineral in bone is carbonated apatite that also contains some fluoride6. Deprotonation of HPO32- occurs at pH 12, which is impossibly high for biological system, and the predominate carbonate species in solution at neutral pH is HCO3-. To produce an apatite mineral without a significant hydroxyl content, it is possible that apatite biomineralization occurs through a polyphosphate pathway, where the oxygen atom required to transform polyphosphate into individual phosphate ions is from carbonate: [PO3-]n + CO32- -> [PO3-]n-1 + PO43- + CO2. Alkaline phosphatase can depolymerise polyphosphate into orthophosphate5. If alkaline phosphatase cleaves an oxygen atom from a calcium-carbonate complex, then there is no requirement for removing a hydrogen atom from the HCO3- or HPO43- ions of body water to form bioapatite. A mix of 1 mL of 1 M calcium polyphosphate hydogel, or nano-particles of calcium polyphosphate, and amorphous calcium carbonate were reacted with alkaline phosphatase, and maintained at neutral to basic pH. After two weeks, carbonated apatite and other calcium phosphate minerals were identified by powder x-ray diffraction. Orthophosphate and unreacted

  11. Oxygen deficiency at CERN: Hazards, risks & mitigation measures

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Compressed and liquified gases are used at many places at CERN. If they are introduced to the atmosphere, they can present an oxygen deficiency hazard (ODH) and lead to reduced abilities, unconsciousness or even death. The CERN method for ODH risk assessments is done on a case-by-case basis as each situation is unique. It is crucial to make sure the personnel can evacuate safely in case of an ODH situation. My talk will explain human reactions to reduced oxygen levels and I will give some practical examples on how one can assess and control the hazards from a possible oxygen deficient atmosphere. Some real accidents involving oxygen deficiency will also be mentioned.

  12. The effect of the oxygen dissolved in the adsorption of gold in activated carbon; Efecto del oxigeno disuelto en la adsorcion de oro en carbon activado

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, P. [Universidad de Santiago. Chile (Chile); Wilkomirsky, I. [Universidad de Concepcion. Chile (Chile)

    1999-07-01

    The effect of the oxygen dissolved on the adsorption of gold in a activated carbon such as these used for carbon in pulp (CIP) and carbon in leach (CIL) processes were studied. The research was oriented to dilucidate the effect of the oxygen dissolved in the gold solution on the kinetics and distribution of the gold adsorbed in the carbon under different conditions of ionic strength, pH and gold concentration. It was found that the level of the oxygen dissolved influences directly the amount of gold adsorbed on the activated carbon, being this effect more relevant for low ionic strength solutions. The pH and initial gold concentration has no effect on this behavior. (Author) 16 refs.

  13. Enhanced electrocatalysis performance of amorphous electrolytic carbon from CO2 for oxygen reduction by surface modification in molten salt

    International Nuclear Information System (INIS)

    Chen, Zhigang; Gu, Yuxing; Du, Kaifa; Wang, Xu; Xiao, Wei; Mao, Xuhui; Wang, Dihua

    2017-01-01

    Highlights: •The potential of electrolytic carbon as catalyst for oxygen reduction was evaluated. •A molten salt method for electrolytic-carbon modification was demonstrated. •The electrolytic carbon was activated for the ORR by the molten salt sulfidation. •Sulfur and cobalt dual modification further improved the ORR activity of the carbon. -- Abstract: The electrolytic carbon (E-carbon) derived from greenhouse gas CO 2 in molten carbonates at mild temperature possesses high electrical conductivity and suitable specific surface area. In this work, its potential as catalyst is investigated towards oxygen reduction reaction (ORR). It is revealed that the pristine E-carbon has no electrocatalytic activity for the ORR due to its high surface content of carboxyl group. The carbon was then treated in a Li 2 SO 4 containing Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 molten salt at 550 °C. Sulfur modified E-carbon was obtained in the melt via a galvanic sulfidation reaction, in which Li 2 SO 4 served as a nontoxic sulfur source and an oxidant. The sulfur modified E-carbon showed a significantly improved electrocatalytic activity. Subsequently, a sulfur/cobalt dual modified carbon with much higher catalysis activity was successfully prepared by treating an E-carbon/CoSO 4 composite in the same melt. The dual modified E-carbon showed excellent catalytic performance with activity close to the commercial Pt/C catalyst but a high tolerance towards methanol.

  14. Carbon Valuation: Alternatives, Alternations and Lateral Measures?

    DEFF Research Database (Denmark)

    Dalsgaard, Steffen

    2016-01-01

    This article refers to carbon valuation as the practice of ascribing value to, and assessing the value of, actions and objects in terms of carbon emissions. Due to the pervasiveness of carbon emissions in the actions and objects of everyday lives of human beings, the making of carbon offsets and ...

  15. Carbon and oxygen isotopic composition of coal and carbon dioxide derived from laboratory coal combustion: A preliminary study

    Science.gov (United States)

    Warwick, Peter D.; Ruppert, Leslie F.

    2016-01-01

    The concentration of carbon dioxide (CO2) in the atmosphere has dramatically increased from the start of the industrial revolution in the mid-1700s to present levels exceeding 400 ppm. Carbon dioxide derived from fossil fuel combustion is a greenhouse gas and a major contributor to on-going climate change. Carbon and oxygen stable isotope geochemistry is a useful tool to help model and predict the contributions of anthropogenic sources of CO2 in the global carbon cycle. Surprisingly few studies have addressed the carbon and oxygen isotopic composition of CO2 derived from coal combustion. The goal of this study is to document the relationships between the carbon and oxygen isotope signatures of coal and signatures of the CO2 produced from laboratory coal combustion in atmospheric conditions.Six coal samples were selected that represent various geologic ages (Carboniferous to Tertiary) and coal ranks (lignite to bituminous). Duplicate splits of the six coal samples were ignited and partially combusted in the laboratory at atmospheric conditions. The resulting coal-combustion gases were collected and the molecular composition of the collected gases and isotopic analyses of δ13C of CO2, δ13C of CH4, and δ18O of CO2 were analysed by a commercial laboratory. Splits (~ 1 g) of the un-combusted dried ground coal samples were analyzed for δ13C and δ18O by the U.S. Geological Survey Reston Stable Isotope Laboratory.The major findings of this preliminary work indicate that the isotopic signatures of δ13C (relative to the Vienna Pee Dee Belemnite scale, VPDB) of CO2 resulting from coal combustion are similar to the δ13CVPDB signature of the bulk coal (− 28.46 to − 23.86 ‰) and are not similar to atmospheric δ13CVPDB of CO2 (~ − 8 ‰, see http://www.esrl.noaa.gov/gmd/outreach/isotopes/c13tellsus.html). The δ18O values of bulk coal are strongly correlated to the coal dry ash yields and appear to have little or no influence on the δ18O values of CO2

  16. Effects of Water Vapor on the Data Quality of the Stable Oxygen Isotopic Ratio of Atmospheric Carbon Dioxide

    Science.gov (United States)

    Evans, C. U.; White, J. W.; Vaughn, B.; Tans, P. P.; Pardo, L.

    2007-12-01

    The stable oxygen isotopic ratio of carbon dioxide can potentially track fundamental indicators of environmental change such as the balance between photosynthesis and respiration on regional to global scales. The Stable Isotope Laboratory (SIL) at the Institute of Arctic and Alpine Research (INSTAAR), University of Colorado at Boulder, has measured the stable isotopes of atmospheric carbon dioxide from more than 60 NOAA/Earth System Research Laboratory (ESRL) air flask-sampling sites since the early 1990s. If air is sampled without drying, oxygen can exchange between carbon dioxide and water in the flasks, entirely masking the desired signal. An attempt to investigate how water vapor is affecting the δ18O signal is accomplished by comparing the SIL measurements with specific humidity, calculated from the National Climatic Data Center (NCDC) global integrated surface hourly temperature and dew point database, at the time of sampling. Analysis of sites where samples have been collected initially without drying, and subsequently with a drying kit, in conjunction with the humidity data, has led to several conclusions. Samples that initially appear isotopically unaltered, in that their δ18O values are within the expected range, are being subtly influenced by the water vapor in the air. At Bermuda and other tropical to semi-tropical sites, the 'wet' sampling values have a seasonal cycle that is strongly anti-correlated to the specific humidity, while the 'dry' values have a seasonal cycle that is shifted earlier than the specific humidity cycle by 1-2 months. The latter phasing is expected given the seasonal phasing between climate over the ocean and land, while the former is consistent with a small, but measurable isotope exchange in the flasks. In addition, we note that there is a strong (r > 0.96) correlation between the average specific humidity and the percent of rejected samples for 'wet' sampling. This presents an opportunity for determining a threshold of

  17. 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.

  18. Seasonal variation in kangaroo tooth enamel oxygen and carbon isotopes in southern Australia

    Science.gov (United States)

    Brookman, Tom H.; Ambrose, Stanley H.

    2012-09-01

    Serial sampling of tooth enamel growth increments for carbon and oxygen isotopic analyses of Macropus (kangaroo) teeth was performed to assess the potential for reconstructing paleoseasonality. The carbon isotope composition of tooth enamel apatite carbonate reflects the proportional intake of C3 and C4 vegetation. The oxygen isotopic composition of enamel reflects that of ingested and metabolic water. Tooth enamel forms sequentially from the tip of the crown to the base, so dietary and environmental changes during the tooth's formation can be detected. δ13C and δ18O values were determined for a series of enamel samples drilled from the 3rd and 4th molars of kangaroos that were collected along a 900 km north-south transect in southern Australia. The serial sampling method did not yield pronounced seasonal isotopic variation patterns in Macropus enamel. The full extent of dietary isotopic variation may be obscured by attenuation of the isotopic signal during enamel mineralisation. Brachydont (low-crowned) Macropus teeth may be less sensitive to seasonal variation in isotopic composition due to time-averaging during mineralisation. However, geographic variations observed suggest that there may be potential for tracking latitudinal shifts in vegetation zones and seasonal environmental patterns in response to climate change.

  19. Aligned carbon nanotube with electro-catalytic activity for oxygen reduction reaction

    Science.gov (United States)

    Liu, Di-Jia; Yang, Junbing; Wang, Xiaoping

    2010-08-03

    A catalyst for an electro-chemical oxygen reduction reaction (ORR) of a bundle of longitudinally aligned carbon nanotubes having a catalytically active transition metal incorporated longitudinally in said nanotubes. A method of making an electro-chemical catalyst for an oxygen reduction reaction (ORR) having a bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes, where a substrate is in a first reaction zone, and a combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into the first reaction zone which is maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is then introduced to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes over the substrate with a catalytically active transition metal incorporated throughout the nanotubes.

  20. Synergistically enhanced activity of nitrogen-doped carbon dots/graphene composites for oxygen reduction reaction

    Science.gov (United States)

    Liu, Hui; Zhao, Qingshan; Liu, Jingyan; Ma, Xiao; Rao, Yuan; Shao, Xiaodong; Li, Zhongtao; Wu, Wenting; Ning, Hui; Wu, Mingbo

    2017-11-01

    With rapid dissociative adsorption of oxygen, nitrogen-doped carbon nanomaterials have been demonstrated to be efficient alternative catalysts for oxygen reduction reaction (ORR) in fuel cells. Herein, we developed a mild hydrothermal strategy to construct nitrogen-doped carbon dots/graphene (NCDs-NG) composites towards ORR. Carbon dots (CDs) were derived from petroleum coke via acid oxidation while graphene oxide (GO) was obtained from graphite by modified Hummer's method. Graphene was employed as a conductive substrate to disperse CDs during hydrothermal reducing reaction while ammonia was utilized as N source to dope both graphene and CDs. The synergistic effects, i.e. CDs as pillars for graphene and catalytic sites for ORR, the high conductivity of graphene, the quick O2 adsorption on doped pyridinic nitrogen endow the NCDs-NG composites with enhanced ORR catalytic performance in alkaline electrolyte. The onset potential of -95 mV and kinetic current density of 12.7 mA cm-2 at -0.7 V (vs. Ag/AgCl) can be compared to those of the commercial 20 wt% Pt/C catalyst. The electron transfer number is about 3.9, revealing a four-electron pathway for ORR. The optimal NCDs-NG catalyst shows superior durability and methanol tolerance than 20 wt% Pt/C. This work demonstrates a feasible and effective strategy to prepare metal-free efficient ORR electrocatalysts for fuel cell applications.

  1. Oxygen- and Nitrogen-Enriched 3D Porous Carbon for Supercapacitors of High Volumetric Capacity.

    Science.gov (United States)

    Li, Jia; Liu, Kang; Gao, Xiang; Yao, Bin; Huo, Kaifu; Cheng, Yongliang; Cheng, Xiaofeng; Chen, Dongchang; Wang, Bo; Sun, Wanmei; Ding, Dong; Liu, Meilin; Huang, Liang

    2015-11-11

    Efficient utilization and broader commercialization of alternative energies (e.g., solar, wind, and geothermal) hinges on the performance and cost of energy storage and conversion systems. For now and in the foreseeable future, the combination of rechargeable batteries and electrochemical capacitors remains the most promising option for many energy storage applications. Porous carbonaceous materials have been widely used as an electrode for batteries and supercapacitors. To date, however, the highest specific capacitance of an electrochemical double layer capacitor is only ∼200 F/g, although a wide variety of synthetic approaches have been explored in creating optimized porous structures. Here, we report our findings in the synthesis of porous carbon through a simple, one-step process: direct carbonization of kelp in an NH3 atmosphere at 700 °C. The resulting oxygen- and nitrogen-enriched carbon has a three-dimensional structure with specific surface area greater than 1000 m(2)/g. When evaluated as an electrode for electrochemical double layer capacitors, the porous carbon structure demonstrated excellent volumetric capacitance (>360 F/cm(3)) with excellent cycling stability. This simple approach to low-cost carbonaceous materials with unique architecture and functionality could be a promising alternative to fabrication of porous carbon structures for many practical applications, including batteries and fuel cells.

  2. Polyaniline-Derived Ordered Mesoporous Carbon as an Efficient Electrocatalyst for Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Kai Wan

    2015-06-01

    Full Text Available Nitrogen-doped ordered mesoporous carbon was synthesized by using polyaniline as the carbon source and SBA-15 as the template. The microstructure, composition and electrochemical behavior were extensively investigated by the nitrogen sorption isotherm, X-ray photoelectron spectroscopy, cyclic voltammetry and rotating ring-disk electrode. It is found that the pyrolysis temperature yielded a considerable effect on the pore structure, elemental composition and chemical configuration. The pyrolysis temperature from 800 to 1100 °C yielded a volcano-shape relationship with both the specific surface area and the content of the nitrogen-activated carbon. Electrochemical tests showed that the electrocatalytic activity followed a similar volcano-shape relationship, and the carbon catalyst synthesized at 1000 °C yielded the best performance. The post-treatment in NH3 was found to further increase the specific surface area and to enhance the nitrogen doping, especially the edge-type nitrogen, which favored the oxygen reduction reaction in both acid and alkaline media. The above findings shed light on electrocatalysis and offer more strategies for the controllable synthesis of the doped carbon catalyst.

  3. Collapse of accreting carbon-oxygen white dwarfs induced by carbon deflagration at high density

    International Nuclear Information System (INIS)

    Nomoto, K.

    1986-01-01

    A critical condition is obtained for which carbon deflagration induces collapse of an accreting C + O white dwarf, not explosion. If the carbon deflagration is initiated at central density as high as 10 10 g cm -3 and if the propagation of the deflagration wave is slower than ∼ 0.15 υ/sub s/ (υ/sub s/ is the sound speed), electron capture behind the burning front induces collapse to form a neutron star. This is the case for both conductive and convective deflagrations. Such a high central density can be reached if the white dwarf is sufficiently massive and cold at the onset of accretion and if the accretion rate is in the appropriate range. Models for Type Ia and Ib supernovae are also discussed. 66 refs., 8 figs

  4. Poster 9: Isotopic Ratios of Carbon and Oxygen in Titan's CO using ALMA

    Science.gov (United States)

    Serigano, Joseph; Nixion, Conor A.; Cordiner, Martin A.; Irwin, Patrick G. J.; Teanby, Nick A.; Charnley, Steven B.; Lindberg, Johan E.

    2016-06-01

    The advent of the Atacama Large Millimeter/Submillimeter Array (ALMA) has provided a new and powerful facility for probing the atmospheres of solar system targets at long wavelengths (84-720 GHz) where the rotational lines of small, polar molecules are prominent. In the complex atmosphere of Titan, photochemical processes dissociate and ionize molecular nitrogen and methane in the upper atmosphere, creating a complex inventory of trace hydrocarbons and nitriles. Additionally, the existence of oxygen on Titan facilitates the synthesis of molecules of potential astrobiological importance. Utilization of ground-based submillimeter observations of Titan has proven to be a powerful tool to complement results from spacecraft observations. ALMA provides the ability to probe this region in greater detail with unprecedented spectral and spatial resolution at high sensitivity, allowing for the derivation of vertical mixing profiles, molecular detections, and observations of latitudinal and seasonal variations. Recent ALMA studies of Titan have presented spectrally and spatially-resolved maps of HNC and HC3N emission (Cordiner et al. 2014), as well as the first spectroscopic detection of ethyl cyanide (C2H5CN) in Titan's atmosphere (Cordiner et al. 2015). This poster will focus on ALMA observations of carbon monoxide (CO) and its isotopologues 13CO, C18O, and C 17O in Titan's atmosphere. Molecular abundances and the vertical atmospheric temperature profile were derived by modeling the observed emission line profiles using NEMESIS, a line-by-line radiative transfer code (Irwin et al. 2008). This study reports the first spectroscopic detection of 17O in the outer solar system with C17O detected at >8σ confidence. The abundances of these molecules and isotopic ratios of 12C/13C, 16O/18O, and 16O/17O will be presented. General implications for the history of Titan from these measurements will be discussed.

  5. KOH-activated multi-walled carbon nanotubes as platinum supports for oxygen reduction reaction

    Science.gov (United States)

    He, Chaoxiong; Song, Shuqin; Liu, Jinchao; Maragou, Vasiliki; Tsiakaras, Panagiotis

    In the present investigation, multi-walled carbon nanotubes (MWCNTs) thermally treated by KOH were adopted as the platinum supporting material for the oxygen reduction reaction electrocatalysts. FTIR and Raman spectra were used to investigate the surface state of MWCNTs treated by KOH at different temperatures (700, 800, and 900 °C) and showed MWCNTs can be successfully functionalized. The structural properties of KOH-activated MWCNTs supported Pt were determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their electrochemical performance was evaluated by the aid of cyclic voltammetry (CV) and rotating disk electrode (RDE) voltammetry. According to the experimental findings of the present work, the surrface of MWCNTs can be successfully functionalized with oxygen-containing groups after activation by KOH, favoring the good dispersion of Pt nanoparticles with narrow size distribution. The as-prepared Pt catalysts supported on KOH treated MWCNTs at higher temperature, possess higher electrochemical surface area and exhibit desirable activity towards oxygen reduction reaction (ORR). More precisely, it has been found that the electrochemical active area of Pt/MWCNTs-900 is approximately two times higher than that of Pt/MWCNTs. It can be concluded that KOH activation is an effective way to decorate MWCNTs' surface with oxygen-containing groups and bigger surface area, which makes them more suitable as electrocatalyst support materials.

  6. Oxygen plasma assisted end-opening and field emission enhancement in vertically aligned multiwall carbon nanotubes

    International Nuclear Information System (INIS)

    Mathur, A.; Roy, S.S.; Hazra, K.S.; Wadhwa, S.; Ray, S.C.; Mitra, S.K.; Misra, D.S.; McLaughlin, J.A.

    2012-01-01

    Highlights: ► We showed Ar/O 2 plasma can be effective for the end opening of aligned CNTs. ► The field emission property was dramatically enhanced after plasma modification. ► Microstructures were clearly understood by Raman and SEM analysis. ► Surface wet-ability at various functionalised conditions was studied. - Abstract: This paper highlights the changes in micro-structural and field emission properties of vertically aligned carbon nanotubes (VACNTs) via oxygen plasma treatment. We find that exposure of very low power oxygen plasma (6 W) at 13.56 MHz for 15–20 min, opens the tip of vertically aligned CNTs. Scanning electron microscopy and transmission electron microscopy images were used to identify the quality and micro-structural changes of the nanotube morphology and surfaces. Raman spectra showed that the numbers of defects were increased throughout the oxygen plasma treatment process. In addition, the hydrophobic nature of the VACNTs is altered significantly and the contact angle decreases drastically from 110° to 40°. It was observed that the electron field emission (EFE) characteristics are significantly enhanced. The turn-on electric field (ETOE) of CNTs decreased from ∼0.80 V μm −1 (untreated) to ∼0.60 V μm −1 (oxygen treated). We believe that the open ended VACNTs would be immensely valuable for applications such as micro/nanofluidic based filtering elements and display devices.

  7. CARBON CHEMISTRY IN THE ENVELOPE OF VY CANIS MAJORIS: IMPLICATIONS FOR OXYGEN-RICH EVOLVED STARS

    International Nuclear Information System (INIS)

    Ziurys, L. M.; Tenenbaum, E. D.; Pulliam, R. L.; Woolf, N. J.; Milam, S. N.

    2009-01-01

    Observations of the carbon-bearing molecules CO, HCN, CS, HNC, CN, and HCO + have been conducted toward the circumstellar envelope of the oxygen-rich red supergiant star, VY Canis Majoris (VY CMa), using the Arizona Radio Observatory (ARO). CO and HCN were also observed toward the O-rich shells of NML Cyg, TX Cam, IK Tau, and W Hya. Rotational transitions of these species at 1 mm, 0.8 mm, and 0.4 mm were measured with the ARO Submillimeter Telescope, including the J = 6 → 5 line of CO at 691 GHz toward TX Cam and W Hya. The ARO 12 m was used for 2 mm and 3 mm observations. Four transitions were observed for HCO + in VY CMa, the first definitive identification of this ion in a circumstellar envelope. Molecular line profiles from VY CMa are complex, indicating three separate outflows: a roughly spherical flow and separate red- and blueshifted winds, as suggested by earlier observations. Spectra from the other sources appear to trace a single outflow component. The line data were modeled with a radiative transfer code to establish molecular abundances relative to H 2 and source distributions. Abundances for CO derived for these objects vary over an order of magnitude, f ∼ 0.4-5 x 10 -4 , with the lower values corresponding to the supergiants. For HCN, a similar range in abundance is found (f ∼ 0.9-9 x 10 -6 ), with no obvious dependence on the mass-loss rate. In VY CMa, HCO + is present in all three outflows with f ∼ 0.4-1.6 x 10 -8 and a spatial extent similar to that of CO. HNC is found only in the red- and blueshifted components with [HCN]/[HNC] ∼ 150-190, while [CN]/[HCN] ∼ 0.01 in the spherical flow. All three velocity components are traced in CS, which has a confined spatial distribution and f ∼ 2-6 x 10 -7 . These observations suggest that carbon-bearing molecules in O-rich shells are produced by a combination of photospheric shocks and photochemistry. Shocks may play a more prominent role in the supergiants because of their macroturbulent

  8. Carbon Chemistry in the Envelope of VY Canis Majoris: Implications for Oxygen-Rich Evolved Stars

    Science.gov (United States)

    Ziurys, L. M.; Tenenbaum, E. D.; Pulliam, R. L.; Woolf, N. J.; Milam, S. N.

    2009-04-01

    Observations of the carbon-bearing molecules CO, HCN, CS, HNC, CN, and HCO+ have been conducted toward the circumstellar envelope of the oxygen-rich red supergiant star, VY Canis Majoris (VY CMa), using the Arizona Radio Observatory (ARO). CO and HCN were also observed toward the O-rich shells of NML Cyg, TX Cam, IK Tau, and W Hya. Rotational transitions of these species at 1 mm, 0.8 mm, and 0.4 mm were measured with the ARO Submillimeter Telescope, including the J = 6 → 5 line of CO at 691 GHz toward TX Cam and W Hya. The ARO 12 m was used for 2 mm and 3 mm observations. Four transitions were observed for HCO+ in VY CMa, the first definitive identification of this ion in a circumstellar envelope. Molecular line profiles from VY CMa are complex, indicating three separate outflows: a roughly spherical flow and separate red- and blueshifted winds, as suggested by earlier observations. Spectra from the other sources appear to trace a single outflow component. The line data were modeled with a radiative transfer code to establish molecular abundances relative to H2 and source distributions. Abundances for CO derived for these objects vary over an order of magnitude, f ~ 0.4-5 × 10-4, with the lower values corresponding to the supergiants. For HCN, a similar range in abundance is found (f ~ 0.9-9 × 10-6), with no obvious dependence on the mass-loss rate. In VY CMa, HCO+ is present in all three outflows with f ~ 0.4-1.6 × 10-8 and a spatial extent similar to that of CO. HNC is found only in the red- and blueshifted components with [HCN]/[HNC] ~ 150-190, while [CN]/[HCN] ~ 0.01 in the spherical flow. All three velocity components are traced in CS, which has a confined spatial distribution and f ~ 2-6 × 10-7. These observations suggest that carbon-bearing molecules in O-rich shells are produced by a combination of photospheric shocks and photochemistry. Shocks may play a more prominent role in the supergiants because of their macroturbulent velocities.

  9. Assembly of Modified Ferritin Proteins on Carbon Nanotubes and its Electrocatalytic Activity for Oxygen Reduction

    Science.gov (United States)

    Kim, Jae-Woo; Lillehei, Peter T.; Park, Cheol

    2012-01-01

    Highly effective dispersions of carbon nanotubes (CNTs) can be made using a commercially available buffer solution. Buffer solutions of 3-(N-morpholino)-propanesulfonic acid (MOPS), which consists of a cyclic ring with nitrogen and oxygen heteroatoms, a charged group, and an alkyl chain greatly enhance the dispersibility and stability of CNTs in aqueous solutions. Additionally, the ability of biomolecules, especially cationized Pt-cored ferritins, to adhere onto the well-dispersed CNTs in the aqueous buffer solution is also improved. This was accomplished without the use of surfactant molecules, which are detrimental to the electrical, mechanical, and other physical properties of the resulting products. The assembled Pt-cored ferritin proteins on the CNTs were used as an electrocatalyst for oxygen reduction

  10. Formation of cerussite and hydrocerussite during adsorption of lead from aqueous solution on oxidized carbons by cold oxygen plasma

    Energy Technology Data Exchange (ETDEWEB)

    De Velasco Maldonado, Paola S. [Instituto Tecnologico de Aguascalientes, Av. Adolfo López Mateos No. 1801 Ote. C.P, Aguascalientes, Ags, 20256 (Mexico); Hernández-Montoya, Virginia, E-mail: virginia.hernandez@yahoo.com.mx [Instituto Tecnologico de Aguascalientes, Av. Adolfo López Mateos No. 1801 Ote. C.P, Aguascalientes, Ags, 20256 (Mexico); Concheso, A.; Montes-Morán, Miguel A. [Instituto Nacional del Carbon, INCAR-CSIC, Apartado 73, E-33080, Oviedo (Spain)

    2016-11-15

    Highlights: • The formation of cerussite and hydrocerussite was observed on the carbon surface. • Occurrence of CaCO{sub 3} on the carbons surface plays a crucial role in the formation. • The carbons were prepared by carbonization and oxidation with cold oxygen plasma. • Oxidation with cold oxygen plasma increases the formation of these compounds. - Abstract: A new procedure of elimination of Pb{sup 2+} from aqueous solution using carbon adsorbents, in which high amounts of cerussite and hydrocerussite are deposited on the carbon surfaces, is reported. The procedure includes the preparation of carbons from selected lignocellulosic wastes (pecan nut shells and peach stones) by single carbonization and further oxidation with cold oxygen plasma. The materials prior and after the oxidation treatment were characterized using elemental analysis, FT-IR spectroscopy, SEM/EDX analysis, adsorption of N{sub 2} at −196 °C and X-ray photoelectron spectroscopy. The adsorption of Pb{sup 2+} was carried out in batch systems under constant agitation. The formation of cerussite and hydrocerussite on the spent carbon surfaces was confirmed by XRD, SEM/EDX and FT-IR. A Pb{sup 2+} removal mechanism is proposed in which a co-precipitation of lead nitrate and calcium carbonate would render the formation of the lead carbonates. In such mechanism, the occurrence of CaCO{sub 3} on the surface of the adsorbents plays a crucial role. The presence of calcium carbonate on the precursors is understood on the basis of the thermal evolution of calcium oxalate originally present in the biomass. The oxygen plasma treatment helps to expose the calcium carbonate nanocrystals thus improving dramatically the removal capacity of Pb{sup 2+}. Accordingly, retention capacities as high as 63 mg of Pb{sup 2+} per gram of adsorbent have been attained.

  11. Formation of cerussite and hydrocerussite during adsorption of lead from aqueous solution on oxidized carbons by cold oxygen plasma

    International Nuclear Information System (INIS)

    De Velasco Maldonado, Paola S.; Hernández-Montoya, Virginia; Concheso, A.; Montes-Morán, Miguel A.

    2016-01-01

    Highlights: • The formation of cerussite and hydrocerussite was observed on the carbon surface. • Occurrence of CaCO_3 on the carbons surface plays a crucial role in the formation. • The carbons were prepared by carbonization and oxidation with cold oxygen plasma. • Oxidation with cold oxygen plasma increases the formation of these compounds. - Abstract: A new procedure of elimination of Pb"2"+ from aqueous solution using carbon adsorbents, in which high amounts of cerussite and hydrocerussite are deposited on the carbon surfaces, is reported. The procedure includes the preparation of carbons from selected lignocellulosic wastes (pecan nut shells and peach stones) by single carbonization and further oxidation with cold oxygen plasma. The materials prior and after the oxidation treatment were characterized using elemental analysis, FT-IR spectroscopy, SEM/EDX analysis, adsorption of N_2 at −196 °C and X-ray photoelectron spectroscopy. The adsorption of Pb"2"+ was carried out in batch systems under constant agitation. The formation of cerussite and hydrocerussite on the spent carbon surfaces was confirmed by XRD, SEM/EDX and FT-IR. A Pb"2"+ removal mechanism is proposed in which a co-precipitation of lead nitrate and calcium carbonate would render the formation of the lead carbonates. In such mechanism, the occurrence of CaCO_3 on the surface of the adsorbents plays a crucial role. The presence of calcium carbonate on the precursors is understood on the basis of the thermal evolution of calcium oxalate originally present in the biomass. The oxygen plasma treatment helps to expose the calcium carbonate nanocrystals thus improving dramatically the removal capacity of Pb"2"+. Accordingly, retention capacities as high as 63 mg of Pb"2"+ per gram of adsorbent have been attained.

  12. Myocardial oxygen extraction fraction measured using bolus inhalation of 15O-oxygen gas and dynamic PET

    NARCIS (Netherlands)

    Lubberink, Mark; Wong, YY; Raijmakers, P. G.; Huisman, Marc C.; Schuit, Robert C.; Luurtsema, Geert; Boellaard, Ronald; Knaapen, P; Vonk-Noordegraaf, Anton; Lammertsma, Adriaan A.

    Abstract The aim of this study was to determine the accuracy of oxygen extraction fraction (OEF) measurements using a dynamic scan protocol after bolus inhalation of 15O2. The method of analysis was optimized by investigating potential reuse of myocardial blood flow (MBF), perfusable tissue

  13. The influence of carbon and oxygen on the magnetic characteristics of press-less sintered NdFeB magnets

    DEFF Research Database (Denmark)

    Xia, Manlong; Abrahamsen, Asger Bech; Bahl, Christian

    2017-01-01

    The Pressless Process (PLP) was adopted to manufacture NdFeB sintered magnets, where the investigations on carbon and oxygen residues from heptane milling liquid media and graphite crucibles used for sintering were quantified to evaluate the influence on the magnetic characteristics. The carbon...

  14. Measurement of oxygen consumption during muscle flaccidity exercise by near-infrared spectroscopy

    Science.gov (United States)

    Fukuda, K.; Fukawa, Y.

    2013-03-01

    Quantitative measurement oxygen consumption in the muscles is important to evaluate the effect of the exercise. Near-infrared spectroscopy (NIRS) is a noninvasive method for measuring muscle oxygenation. However, measurement results are affected by blood volume change due to changes in the blood pressure. In order to evaluate changes in blood volume and to improve measurement accuracy, we proposed a calculation method of three-wavelength measurement with considering the scattering factor and the measurement with monitoring blood flow for measuring the temporal change of the oxygen concentration more precisely. We applied three-wavelength light source (680nm, 808nm and 830nm) for the continued wave measurement. Two detectors (targeted detector and the reference detector) were placed near the target muscle and apart from it. We measured the blood flow by controlling the intravascular pressure and the oxygen consumption with the handgrip exercise in the forearm. The measured results show that the scattering factor contains the artifact at the surface and the blood flow in the artery and the vein in the same phase. The artifact and the blood flow in the same phase are reduced from the oxygenated and the deoxygenated hemoglobin densities. Thus our proposed method is effective for reducing the influence of the artifact and the blood flow in the same phase from the oxygen consumption measurement. Further, it is shown that the oxygen consumption is measured more accurately by subtracting the blood flow measured by the reference detector.

  15. Formation and annealing of metastable (interstitial oxygen)-(interstitial carbon) complexes in n- and p-type silicon

    CERN Document Server

    Makarenko, L F; Lastovskii, S B; Murin, L I; Moll, M; Pintilie, I

    2014-01-01

    It is shown experimentally that, in contrast to the stable configuration of (interstitial carbon)-(interstitial oxygen) complexes (CiOi), the corresponding metastable configuration (CiOi{*}) cannot be found in n-Si based structures by the method of capacitance spectroscopy. The rates of transformation CiOi{*} -> CiOi are practically the same for both n- and p-Si with a concentration of charge carriers of no higher than 10(13) cm(-3). It is established that the probabilities of the simultaneous formation of stable and metastable configurations of the complex under study in the case of the addition of an atom of interstitial carbon to an atom of interstitial oxygen is close to 50\\%. This is caused by the orientation dependence of the interaction potential of an atom of interstitial oxygen with an interstitial carbon atom, which diffuses to this oxygen atom.

  16. Simultaneous determination of stable carbon, oxygen, and hydrogen isotopes in cellulose.

    Science.gov (United States)

    Loader, N J; Street-Perrott, F A; Daley, T J; Hughes, P D M; Kimak, A; Levanič, T; Mallon, G; Mauquoy, D; Robertson, I; Roland, T P; van Bellen, S; Ziehmer, M M; Leuenberger, M

    2015-01-06

    A technological development is described through which the stable carbon-, oxygen-, and nonexchangeable hydrogen-isotopic ratios (δ(13)C, δ(18)O, δ(2)H) are determined on a single carbohydrate (cellulose) sample with precision equivalent to conventional techniques (δ(13)C 0.15‰, δ(18)O 0.30‰, δ(2)H 3.0‰). This triple-isotope approach offers significant new research opportunities, most notably in physiology and medicine, isotope biogeochemistry, forensic science, and palaeoclimatology, when isotopic analysis of a common sample is desirable or when sample material is limited.

  17. Hetero-atom doped carbon nanotubes for dye degradation and oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Nandan, Ravi, E-mail: aerawat27@gmail.com; Nanda, Karuna Kar [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India)

    2015-06-24

    We report the synthesis of nitrogen doped vertically aligned multi-walled (MWNCNTs) carbon nanotubes by pyrolysis and its catalytic performance for degradation of methylene blue (MB) dye & oxygen reduction reaction (ORR). The degradation of MB was monitored spectrophotometrically with time. Kinetic studies show the degradation of MB follows a first order kinetic with rate constant k=0.0178 min{sup −1}. The present rate constant is better than that reported for various supported/non-supported semiconducting nanomaterials. Further ORR performance in alkaline media makes MWNCNTs a promising cost-effective, fuel crossover tolerance, metal-free, eco-friendly cathode catalyst for direct alcohol fuel cell.

  18. Microstructure and tribology of carbon, nitrogen, and oxygen implanted ferrous materials

    International Nuclear Information System (INIS)

    Williamson, D.L.

    1993-01-01

    Nitrogen, carbon, and oxygen ions have been implanted into ferrous materials under unusual conditions of elevated temperatures and very high dose rates. The tribological durabilities of the resulting surfaces are examined with a special type of pin-on-disc wear test apparatus and found in most cases to be dramatically improved compared to surfaces prepared with conventional implantation conditions. Near-surface microstructures and compositions are characterized after implantation and after wear testing by backscatter Moessbauer spectroscopy, X-ray diffraction, scanning electron microscopy, and Auger electron spectroscopy. These data provide evidence for the predominant mechanisms responsible for the observed sliding wear behavior induced by each of the three species. (orig.)

  19. Metal-phthalocyanine functionalized carbon nanotubes as catalyst for the oxygen reduction reaction: A theoretical study

    Science.gov (United States)

    Orellana, Walter

    2012-07-01

    The covalent functionalization of metallic single-walled carbon nanotubes (CNTs) with transition metal phthalocyanines (MPc, with M = Mn, Fe and Co) are addressed by density functional calculations. The CNT-MPc catalytic activity toward the oxygen reduction reaction (ORR) is investigated through the O2 stretching frequency adsorbed on the phthalocyanine metal center. We find better reduction abilities when the CNT functionalization occurs through sp2-like bonds. Multiple stable-spin states for the M-O2 adduct are also found for M = Mn and Fe, suggesting higher ORR rates. The CNT-MPc complexes show metallic characteristics, suggesting favorable conditions to work as ORR cathode catalysts in fuel cells.

  20. Locations of oxygen, nitrogen and carbon atoms in vanadium determined by neutron diffraction

    International Nuclear Information System (INIS)

    Hiraga, K.; Onozuka, T.; Hirabayashi, M.

    1977-01-01

    The occupation sites of oxygen, nitrogen, and carbon atoms dissolved interstitially in vanadium have been determined by means of neutron diffraction with use of single crystals of VOsub(0.032), VNsub(0.013) and VCsub(0.006). It is revealed that the interstitial atoms occupy, randomly, the octahedral sites in the b.c.c. host lattice of the three crystals. Neutron diffraction is advantageous for the present purpose, since the coherent scattering amplitudes of the solute atoms are much larger than that of the vanadium atom. (Auth.)

  1. Participation of oxygen and carbon in formation of oxidation-induced stacking faults in monocrystalline silicon

    Directory of Open Access Journals (Sweden)

    Иван Федорович Червоный

    2015-11-01

    Full Text Available It is experimentally established, that density of oxidation-induced stacking faults (OISF in the boron doped monocrystalline silicon plates, that above, than it is more relation of oxygen atoms concentration to carbon atoms concentration in them.On research results of geometry of OISF rings in the different sections of single-crystal geometry of areas is reconstructed with their different closeness. At adjustment of the growing modes of single-crystals of silicon the increase of output of suitable product is observed

  2. Dielectronic recombination of carbon, oxygen and iron in low-density and high-temperature plasmas

    International Nuclear Information System (INIS)

    Nakamura, Yukiharu; Kasai, Satoshi; Tazima, Teruhiko

    1977-03-01

    The coefficient of dielectronic recombination, which is one of the important atomic processes in tokamak plasmas, is evaluated by a semiclassical method neglecting the effects of the density and the radiation fields. Those of carbon, oxygen and iron, which play important roles in such as plasma resistivity and energy losses, are calculated numerically in the range of the electron temperature of 10 eV - 10 keV. Compared with the results obtained from Burgess equation, which is most useful for the ions with effective nuclear charge z 25 such as molybdenum. (auth.)

  3. Measurement of carbon-14 in hydrological samples

    International Nuclear Information System (INIS)

    Hussain, S.D.

    1991-11-01

    Thermal neutrons produced by cosmic rays or nuclear weapon tests interact with atmospheric nitrogen resulting in the formation of radiocarbon which, after oxidation into carbon dioxide, follows the natural carbon cycle. The partial pressure of carbon dioxide in the soil is several times that in the atmosphere due to plant root respiration and decay of organic matter. Water absorbs biogenic carbon dioxide while percolating through the unsaturated zone. The carbon content of groundwater is mainly in the form of bicarbonate ions. The extraction of carbon from water sample as barium carbonate is carried out in the field. Benzene is synthesised from the carbonate sample. The activity of radiocarbon in the synthesised benzene is determined by using a liquid scintillation analyzer. Details of sampling procedure, benzene synthesis, counter calibration and treatment of sample data have been given. 7 figs. (author)

  4. 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 ...

  5. Absolute quantum yield measurements for the formation of oxygen ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The dynamics of formation of oxygen atoms after UV photoexcitation of .... The SO2 pressure in the cell was typically 30–55 mTorr (monitored by an MKS .... With this value the quantum yield for O(3P) formation could be calculated to.

  6. Calcium and chemical looping technology for power generation and carbon dioxide (CO2) capture solid oxygen- and CO2-carriers

    CERN Document Server

    Fennell, Paul

    2015-01-01

    Calcium and Chemical Looping Technology for Power Generation and Carbon Dioxide (CO2) Capture reviews the fundamental principles, systems, oxygen carriers, and carbon dioxide carriers relevant to chemical looping and combustion. Chapters review the market development, economics, and deployment of these systems, also providing detailed information on the variety of materials and processes that will help to shape the future of CO2 capture ready power plants. Reviews the fundamental principles, systems, oxygen carriers, and carbon dioxide carriers relevant to calcium and chemical loopingProvi

  7. The hydrogen and oxygen content of self-supporting carbon foils prepared by dc glow discharge in ethylene

    International Nuclear Information System (INIS)

    Tait, N.R.S.; Tolfree, D.W.L.; John, P.; Odeh, I.M.; Thomas, M.J.K.; Tricker, M.J.; Wilson, J.J.B.; England, J.B.A.; Newton, D.

    1980-01-01

    The hydrogen and oxygen content of self-supporting carbon films produced by dc glow discharge have been determined using a precise method involving the elastic scattering of 25 MeV α-particles. The number of carbon-hydrogen bonds has been determined for similar samples using infrared spectroscopy. The results are compared with those for samples made by the carbon arc process. Assuming that the glow discharge carbon contains graphitic regions surrounded by amorphous tetrahedrally bonded material to which hydrogen can attach, a simple estimate is made of the relative numbers of carbon atoms in the two forms. (orig.)

  8. Outcome of mass transfer in a carbon-oxygen white dwarf binary system

    International Nuclear Information System (INIS)

    Khokhlov, A.M.

    1985-01-01

    The hydrostatic evolution of a carbon-oxygen white dwarf (COWD) experiencing accretion of matter from its companion, a second COWD, is calculated for accretion rates ranging from 10 to the -8th to 10 to the -5th solar masses per year. It is shown that, for accretion rates less than (3.3 + or - 1.5) x 10 to the -6th M/yr, the accretion of a C+O mixture by a COWD will ultimately lead to ignition of carbon at the center of the star, producing a thermonuclear explosion. For accretion rates greater than that value, the C-12 can be ignited near the white dwarf surface, followed by propagation of the thermonuclear burning front toward the center. It is concluded that a COWD accreting a C+O mixture is a highly plausible candidate for a type I presupernova. 18 references

  9. Carbon dots decorated vertical SnS{sub 2} nanosheets for efficient photocatalytic oxygen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Zhongzhou [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); Wang, Fengmei; Shifa, Tofik Ahmed; Liu, Kaili; Huang, Yun; Jiang, Chao; He, Jun, E-mail: hej@nanoctr.cn [CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190 (China); Liu, Quanlin [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2016-08-01

    Metal sulfides are highly desirable materials for photocatalytic water splitting because of their appropriate energy bands. However, the poor stability under light illumination in water hinders their wide applications. Here, two-dimensional SnS{sub 2} nanosheets, along with carbon dots of the size around 10 nm, are uniformly grown on fluorine doped tin oxide glasses with a layer of nickel nanoparticles. Significantly, strong light absorption and enhanced photocurrent density are achieved after integration of SnS{sub 2} nanosheets with carbon dots. Notably, the rate of oxygen evolution reached up to 1.1 mmol g{sup −1} h{sup −1} under simulated sunlight irradiation featuring a good stability.

  10. Carbon dots decorated vertical SnS_2 nanosheets for efficient photocatalytic oxygen evolution

    International Nuclear Information System (INIS)

    Cheng, Zhongzhou; Wang, Fengmei; Shifa, Tofik Ahmed; Liu, Kaili; Huang, Yun; Jiang, Chao; He, Jun; Liu, Quanlin

    2016-01-01

    Metal sulfides are highly desirable materials for photocatalytic water splitting because of their appropriate energy bands. However, the poor stability under light illumination in water hinders their wide applications. Here, two-dimensional SnS_2 nanosheets, along with carbon dots of the size around 10 nm, are uniformly grown on fluorine doped tin oxide glasses with a layer of nickel nanoparticles. Significantly, strong light absorption and enhanced photocurrent density are achieved after integration of SnS_2 nanosheets with carbon dots. Notably, the rate of oxygen evolution reached up to 1.1 mmol g"−"1 h"−"1 under simulated sunlight irradiation featuring a good stability.

  11. Effect of solvent on Se-modified ruthenium/carbon catalyst for oxygen reduction

    Directory of Open Access Journals (Sweden)

    Chuanxiang Zhang

    2014-12-01

    Full Text Available Se-modified ruthenium supporting on carbon (Sex–Ru/C electrocatalyst was prepared by solvothermal one-step synthesis method. The reaction mechanism was revealed after discussing impact of different solvents (i-propanol and EG in solvotermal reaction. The result showed that the grain size of Se-modified ruthenium electrocatalyst was as small as 1 to 3 nm and highly dispersed on carbon surface. X-ray photoelectron spectroscopy (XPS presented that selenium mainly existed in the catalyst in the form of elemental selenium and selenium oxides when the solvent was EG and i-propanol, respectively. The oxygen reduction reaction (ORR performance was improved by appearance of selenium oxides.

  12. The influence of carbon and oxygen on the magnetic characteristics of press-less sintered NdFeB magnets

    Science.gov (United States)

    Xia, M.; Abrahamsen, A. B.; Bahl, C. R. H.; Veluri, B.; Søegaard, A. I.; Bøjsøe, P.; Millot, S.

    2017-01-01

    The Pressless Process (PLP) was adopted to manufacture NdFeB sintered magnets, where the investigations on carbon and oxygen residues from heptane milling liquid media and graphite crucibles used for sintering were quantified to evaluate the influence on the magnetic characteristics. The carbon and oxygen content in the magnets produced from wet ball milling of strip cast flakes was found to be of the order 104 ppm and 4·104 ppm respectively, which resulted in soft magnetic behavior. However using jet milling the carbon and oxygen concentration were decreased by an order of magnitude resulting in coercivity of up to 829 kA/m. Thus the influence of the carbon from the graphite crucibles is small.

  13. A Simple Experiment To Measure the Content of Oxygen in the Air Using Heated Steel Wool

    Science.gov (United States)

    Vera, Francisco; Rivera, Rodrigo; Nunez, Cesar

    2011-01-01

    The typical experiment to measure the oxygen content in the atmosphere uses the rusting of steel wool inside a closed volume of air. Two key aspects of this experiment that make possible a successful measurement of the content of oxygen in the air are the use of a closed atmosphere and the use of a chemical reaction that involves the oxidation of…

  14. Measurement of carbon thermodynamic activity in sodium

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, F A; Zagorulko, Yu I; Kovalev, Yu P; Alekseev, V V [Institute of Physics and Power Engineering, Obninsk (USSR)

    1980-05-01

    The report presents the brief outline on system of carbon activity detecting system in sodium (SCD), operating on the carbon-permeable membrane, of the methods and the results of testing it under the experimental circulating loop conditions. The results of carbon activity sensor calibration with the use of equilibrium samples of XI8H9, Fe -8Ni, Fe -12Mn materials are listed. The behaviour of carbon activity sensor signals in sodium under various transitional conditions and hydrodynamic perturbation in the circulating loop, containing carbon bearing impurities in the sodium flow and their deposits on the surfaces flushed by sodium, are described. (author)

  15. Non-destructive estimates of soil carbonic anhydrase activity and associated soil water oxygen isotope composition

    Science.gov (United States)

    Jones, Sam P.; Ogée, Jérôme; Sauze, Joana; Wohl, Steven; Saavedra, Noelia; Fernández-Prado, Noelia; Maire, Juliette; Launois, Thomas; Bosc, Alexandre; Wingate, Lisa

    2017-12-01

    The contribution of photosynthesis and soil respiration to net land-atmosphere carbon dioxide (CO2) exchange can be estimated based on the differential influence of leaves and soils on budgets of the oxygen isotope composition (δ18O) of atmospheric CO2. To do so, the activity of carbonic anhydrases (CAs), a group of enzymes that catalyse the hydration of CO2 in soils and plants, needs to be understood. Measurements of soil CA activity typically involve the inversion of models describing the δ18O of CO2 fluxes to solve for the apparent, potentially catalysed, rate of CO2 hydration. This requires information about the δ18O of CO2 in isotopic equilibrium with soil water, typically obtained from destructive, depth-resolved sampling and extraction of soil water. In doing so, an assumption is made about the soil water pool that CO2 interacts with, which may bias estimates of CA activity if incorrect. Furthermore, this can represent a significant challenge in data collection given the potential for spatial and temporal variability in the δ18O of soil water and limited a priori information with respect to the appropriate sampling resolution and depth. We investigated whether we could circumvent this requirement by inferring the rate of CO2 hydration and the δ18O of soil water from the relationship between the δ18O of CO2 fluxes and the δ18O of CO2 at the soil surface measured at different ambient CO2 conditions. This approach was tested through laboratory incubations of air-dried soils that were re-wetted with three waters of different δ18O. Gas exchange measurements were made on these soils to estimate the rate of hydration and the δ18O of soil water, followed by soil water extraction to allow for comparison. Estimated rates of CO2 hydration were 6.8-14.6 times greater than the theoretical uncatalysed rate of hydration, indicating that CA were active in these soils. Importantly, these estimates were not significantly different among water treatments, suggesting

  16. Oxygen- and nitrogen-chemisorbed carbon nanostructures for Z-scheme photocatalysis applications

    International Nuclear Information System (INIS)

    Qian Zhao; Pathak, Biswarup; Nisar, Jawad; Ahuja, Rajeev

    2012-01-01

    Here focusing on the very new experimental finding on carbon nanomaterials for solid-state electron mediator applications in Z-scheme photocatalysis, we have investigated different graphene-based nanostructures chemisorbed by various types and amounts of species such as oxygen (O), nitrogen (N) and hydroxyl (OH) and their electronic structures using density functional theory. The work functions of different nanostructures have also been investigated by us to evaluate their potential applications in Z-scheme photocatalysis for water splitting. The N-, O–N-, and N–N-chemisorbed graphene-based nanostructures (32 carbon atoms supercell, corresponding to lattice parameter of about 1 nm) are found promising to be utilized as electron mediators between reduction level and oxidation level of water splitting. The O- or OH-chemisorbed nanostructures have potential to be used as electron conductors between H 2 -evolving photocatalysts and the reduction level (H + /H 2 ). This systematic study is proposed to understand the properties of graphene-based carbon nanostructures in Z-scheme photocatalysis and guide experimentalists to develop better carbon-based nanomaterials for more efficient Z-scheme photocatalysis applications in the future.

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

    International Nuclear Information System (INIS)

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

    1995-01-01

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

  18. An experimental study on the effect of carbonic anhydrase on the oxygen isotope exchange kinetics and equilibrium in the carbonic acid system

    Science.gov (United States)

    Uchikawa, J.; Zeebe, R. E.

    2011-12-01

    Stable oxygen isotopes of marine biogenic carbonates are often depleted in 18O relative to the values expected for thermodynamic equilibrium with ambient seawater. One possibility is that 18O-depletion in carbonates is kinetically controlled. The kinetic isotope effect associated with the hydration of CO2 results in 18O-depleted HCO3-. If the HCO3- is utilized before re-establishing equilibrium with ambient water under rapid calcification, the 18O-depletion will be recorded in carbonates. But one caveat in this kinetic model is the fact that many marine calcifiers posses carbonic anhydrase, a zinc-bearing enzyme that catalyzes the CO2 hydration reaction. It is expected that this enzyme accelerates 18O-equilibration in the carbonic acid system by facilitating direct oxygen isotope exchange between HCO3- and H2O via CO2 hydration. Clearly this argues against the conceptual framework of the kinetic model. Yet the critical variable here is the effectiveness of the carbonic anhydrase, which is likely to depend on its concentration and the carbonate chemistry of the aqueous medium. It is also hitherto unknown whether the presence of carbonic anhydrase alters the equilibrium oxygen isotope fractionations between dissolved carbonate species and water. We performed a series of quantitative inorganic carbonate precipitation experiments to examine the changes in the oxygen isotope equilibration time as a function of carbonic anhydrase concentrations. We conducted experiments at pH 8.3 and 8.9. These pH values are similar to the average surface ocean pH and the elevated pH levels observed within calcification microenvironments of certain corals and planktonic foraminifera. A summary of our new experimental results will be presented.

  19. Mesoporous N-doped carbons prepared with thermally removable nanoparticle templates: an efficient electrocatalyst for oxygen reduction reaction.

    Science.gov (United States)

    Niu, Wenhan; Li, Ligui; Liu, Xiaojun; Wang, Nan; Liu, Ji; Zhou, Weijia; Tang, Zhenghua; Chen, Shaowei

    2015-04-29

    Thermally removable nanoparticle templates were used for the fabrication of self-supported N-doped mesoporous carbons with a trace amount of Fe (Fe-N/C). Experimentally Fe-N/C was prepared by pyrolysis of poly(2-fluoroaniline) (P2FANI) containing a number of FeO(OH) nanorods that were prepared by a one-pot hydrothermal synthesis and homogeneously distributed within the polymer matrix. The FeO(OH) nanocrystals acted as rigid templates to prevent the collapse of P2FANI during the carbonization process, where a mesoporous skeleton was formed with a medium surface area of about 400 m(2)/g. Subsequent thermal treatments at elevated temperatures led to the decomposition and evaporation of the FeO(OH) nanocrystals and the formation of mesoporous carbons with the surface area markedly enhanced to 934.8 m(2)/g. Electrochemical measurements revealed that the resulting mesoporous carbons exhibited apparent electrocatalytic activity for oxygen reduction reactions (ORR), and the one prepared at 800 °C (Fe-N/C-800) was the best among the series, with a more positive onset potential (+0.98 V vs RHE), higher diffusion-limited current, higher selectivity (number of electron transfer n > 3.95 at +0.75 V vs RHE), much higher stability, and stronger tolerance against methanol crossover than commercial Pt/C catalysts in a 0.1 M KOH solution. The remarkable ORR performance was attributed to the high surface area and sufficient exposure of electrocatalytically active sites that arose primarily from N-doped carbons with minor contributions from Fe-containing species.

  20. Mass-spectrometric analysis of trace oxygen in carbon dioxide; Analyse de traces d'oxygene dans le gaz carbonique par spectrometrie de masse

    Energy Technology Data Exchange (ETDEWEB)

    Nief, G; Severin, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    The mass spectrum of pure CO{sub 2} contains a peak of weight 32 whose relationship to peak at 44 varies greatly depending on the previous history of the source of ions and even during the course of an analysis. The fact that this peak is more or less proportional to the pressure and that its appearance potential is the same as that of oxygen leads us to suppose that it is produced from oxygen formed by dissociation of the carbon dioxide on the tungsten filament. A prior treatment of the ion source with acetylene reduces the ratio 32/44 to a value of about 15.10{sup -5}. This same treatment also stabilises the spectrometer's sensitivity to oxygen. Two lines of introduction enable pure carbon dioxide, the specimen to be estimated and a reference mixture of known oxygen content to be sent into the mass spectrometer in quick succession. Oxygen in the carbon dioxide in amounts ranging between 0 and 500 p.p.m. can thus be determined to an accuracy of {+-} 5 p.p.m., the analysis taking 30 minutes. (author) [French] Le spectre de masse de CO{sub 2} pur contient un pic de masse 32 dont le rapport au pic 44 varie enormement suivant l'histoire anterieure de la source d'ions et meme au cours d'une analyse. Le fait que ce pic soit grossierement proportionnel a la pression et que son potentiel d'apparition soit le meme que celui de l'oxygene permet de supposer qu'il est engendre a partir de l'oxygene produit par dissociation du gaz carbonique sur le filament de tungstene. Un conditionnement prealable de la source d'ions avec de l'acetylene reduit le rapport 32/44 a une valeur d'environ 15.10{sup -5}. Ce meme traitement stabilise egalement la sensibilite du spectrometre vis-a-vis de l'oxygene. Une double ligne d'introduction de gaz permet d'envoyer en successions rapides dans le spectrometre de masse le gaz carbonique pur, l'echantillon a doser et un melange de reference de teneur en oxygene connue. On arrive ainsi a doser l'oxygene dans le gaz carbonique dans la gamme de 0 a

  1. Oxygen-induced Decrease in the Equilibrium Adsorptive Capacities of Activated Carbons

    OpenAIRE

    Ovín Ania, María Concepción; Parra Soto, José Bernardo; Pis Martínez, José Juan

    2004-01-01

    Special attention was paid in this work to the role of surface chemistry in the adsorption of phenol and salicylic acid onto activated carbons. To this end, two commercial activated carbons (granular and powdered) were oxidised using ammonium peroxodisulphate [(NH4) 2S2O8] and nitric acid in different concentrations. The structural and chemical properties of the oxidised adsorbents were characterised via nitrogen adsorption isotherms measured at –196 ° C and Boehm titrations. Phenol adsorptio...

  2. Competition for inorganic carbon between oxygenic and anoxygenic phototrophs in a hypersaline microbial mat, Guerrero Negro, Mexico

    DEFF Research Database (Denmark)

    Finke, Niko; Hoehler, Tori M.; Polerecky, Lubos

    2013-01-01

    While most oxygenic phototrophs harvest light only in the visible range (400-700 nm, VIS), anoxygenic phototrophs can harvest near infrared light (> 700 nm, NIR). To study interactions between the photosynthetic guilds we used microsensors to measure oxygen and gross oxygenic photosynthesis (gOP)...

  3. 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.

  4. Carbon 13 and oxygen 18 isotope record of the early eocene nammal formation, salt range, pakistan

    International Nuclear Information System (INIS)

    Ghazi, S.; Sajid, Z.

    2014-01-01

    The Nammal Formation is the lowermost unit of the Early Eocene succession in the Salt Range, Pakistan. It is well exposed throughout the Salt Range. The Nammal Formation having 30 to 35 meters thickness is predominantly composed of nodular limestone interbedded with marl and shale. The present study was focussed on stable carbon 13 and oxygen 18 isotopic analysis based on data from two stratigraphically important sections. The samples from the Nilawahan section provided with the delta 13C values varied between 1.34 to -1.56 (VPDB) and values of delta 18O fluctuated between -4.47 to -6.59 (VPDB). Likewise the sample analysis of BadshahPur section exhibited that the delta 13C values changes from 1.09 to -1.65 (VPDB) and delta 18O values range from -4.17 to -6.85 (VPDB). The isotopic records of carbon 13 and oxygen 18 indicated the shallow marine deposition of the Nammal Formation under tropical conditions. It highlighted the palaeo climatic and diagenetic conditions of the Nammal Formation at the time of deposition in the Salt Range region. (author)

  5. Carbon monoxide measurements at Mace Head, Ireland

    Science.gov (United States)

    Doddridge, Bruce G.; Dickerson, Russell R.; Spain, T. Gerard; Oltmans, Samuel J.; Novelli, Paul C.

    1994-01-01

    The North Atlantic Ocean is bordered by continents which may each, under the influence of seasonal weather patterns, act as sources of natural and anthropogenic trace gas and particulate species. Photochemically active species such as carbon monoxide (CO) react to form ozone (O3), a species of critical importance in global climate change. CO is sparingly soluble in water, and the relatively long lifetime of CO in the troposphere makes this species an ideal tracer of air masses with origin over land. We have measured CO using a nondispersive infrared gas filter correlation analyzer at Mace Head on the west coast of Ireland nearly continuously since August 9, 1991. Measurements of CO were acquired at 20-sec resolution and recorded as 60-sec averages. Daily, monthly, and diurnal variation data characteristics of CO mixing ratios observed at this site are reported. Depending on source regions of air parcels passing over this site, 60-min concentrations of CO range from clean air values of approximately 90 ppbv to values in excess of 300 ppbv. Data characterizing the correlation between 60-min CO and O3 mixing ratio data observed at this site are reported also.

  6. Oxygen- and Lithium-Doped Hybrid Boron-Nitride/Carbon Networks for Hydrogen Storage.

    Science.gov (United States)

    Shayeganfar, Farzaneh; Shahsavari, Rouzbeh

    2016-12-20

    Hydrogen storage capacities have been studied on newly designed three-dimensional pillared boron nitride (PBN) and pillared graphene boron nitride (PGBN). We propose these novel materials based on the covalent connection of BNNTs and graphene sheets, which enhance the surface and free volume for storage within the nanomaterial and increase the gravimetric and volumetric hydrogen uptake capacities. Density functional theory and molecular dynamics simulations show that these lithium- and oxygen-doped pillared structures have improved gravimetric and volumetric hydrogen capacities at room temperature, with values on the order of 9.1-11.6 wt % and 40-60 g/L. Our findings demonstrate that the gravimetric uptake of oxygen- and lithium-doped PBN and PGBN has significantly enhanced the hydrogen sorption and desorption. Calculations for O-doped PGBN yield gravimetric hydrogen uptake capacities greater than 11.6 wt % at room temperature. This increased value is attributed to the pillared morphology, which improves the mechanical properties and increases porosity, as well as the high binding energy between oxygen and GBN. Our results suggest that hybrid carbon/BNNT nanostructures are an excellent candidate for hydrogen storage, owing to the combination of the electron mobility of graphene and the polarized nature of BN at heterojunctions, which enhances the uptake capacity, providing ample opportunities to further tune this hybrid material for efficient hydrogen storage.

  7. Successful Treatment of Severe Carbon Monoxide Poisoning and Refractory Shock Using Extracorporeal Membrane Oxygenation.

    Science.gov (United States)

    Teerapuncharoen, Krittika; Sharma, Nirmal S; Barker, Andrew B; Wille, Keith M; Diaz-Guzman, Enrique

    2015-09-01

    Carbon monoxide (CO) is the most common cause of poisoning and poisoning-related death in the United States. It is a tasteless and odorless poisonous gas produced from incomplete combustion of hydrocarbons, such as those produced by cars and heating systems. CO rapidly binds to hemoglobin to form carboxyhemoglobin, leading to tissue hypoxia, multiple-organ failure, and cardiovascular collapse. CO also binds to myocardial myoglobin, preventing oxidative phosphorylation in cardiac mitochondria and resulting in cardiac ischemia or stunning and cardiogenic pulmonary edema. Treatment of CO poisoning is mainly supportive, and supplemental oxygen remains the cornerstone of therapy, whereas hyperbaric oxygen therapy is considered for patients with evidence of neurological and myocardial injury. Extracorporeal membrane oxygenation (ECMO) has been utilized effectively in patients with respiratory failure and hemodynamic instability, but its use has rarely been reported in patients with CO poisoning. We report the successful use of venoarterial ECMO in a patient with severe CO poisoning and multiple-organ failure. Copyright © 2015 by Daedalus Enterprises.

  8. Improving the capacity of lithium-sulfur batteries by tailoring the polysulfide adsorption efficiency of hierarchical oxygen/nitrogen-functionalized carbon host materials.

    Science.gov (United States)

    Schneider, Artur; Janek, Jürgen; Brezesinski, Torsten

    2017-03-22

    The use of monolithic carbons with structural hierarchy and varying amounts of nitrogen and oxygen functionalities as sulfur host materials in high-loading lithium-sulfur cells is reported. The primary focus is on the strength of the polysulfide/carbon interaction with the goal of assessing the effect of (surface) dopant concentration on cathode performance. The adsorption capacity - which is a measure of the interaction strength between the intermediate lithium polysulfide species and the carbon - was found to scale almost linearly with the nitrogen level. Likewise, the discharge capacity of lithium-sulfur cells increased linearly. This positive correlation can be explained by the favorable effect of nitrogen on both the chemical and electronic properties of the carbon host. The incorporation of additional oxygen-containing surface groups into highly nitrogen-functionalized carbon helped to further enhance the polysulfide adsorption efficiency, and therefore the reversible cell capacity. Overall, the areal capacity could be increased by almost 70% to around 3 mA h cm -2 . We believe that the design parameters described here provide a blueprint for future carbon-based nanocomposites for high-performance lithium-sulfur cells.

  9. Using Oxygen and Carbon Isotopic Signatures in Order to Infer Climatic and Dietary Information in Roman Edessa, Greece

    Science.gov (United States)

    Michael, Dimitra-Ermioni; Dotsika, Elissavet

    2017-12-01

    Even though many isotopic studies have been conducted on ancient populations from Greece for the purpose of dietary reconstruction; mostly through carbon and nitrogen isotopic signals of bone collagen, less attention has been given to the utility of apatite signatures (oxygen and carbon) as dietary and palaeoenvironmental tools. Moreover, until recently the isotopic signal of tooth enamel for both the purposes of environmental and dietary reconstructions has been rarely assessed in ancient Greek societies. Therefore, the present study aims to provide with novel isotopic information regarding Edessa; a town in Northern Greece, during the Roman period. The current study primarily aims to explore the possible differentiation between the present climatic conditions in Edessa in relation to those occurring at the Roman period. Secondly, this study aims to reveal the significant utility of enamel isotopic signatures (carbon and oxygen) in palaeoenvironmental and palaeodietary studies regarding ancient human remains. The isotopic analyses have been conducted at the Stable Isotope and Radiocarbon Unit of INN, NCSR “Demokritos”. The population of Roman Edessa (2nd-4th c. AD) consists of 22 individuals, providing with 19 bone samples and 16 enamel ones. The mean enamel oxygen value is at -7.7 ±1.1 %0, the bone apatite mean oxygen value at -9.2 ±1.9 %0, and finally the mean carbon enamel value is at -11.7 ±1.2 %0. Oxygen values probably indicate that Edessa had a cooler climate during the Roman times in relation to present conditions, even though more research should be carried out in order to be more certain. In addition, the possible existence of non-local individuals has been revealed through the oxygen teeth enamel-bone apatite spacing. Finally, the carbon enamel signature has pointed out possible differentiations between the adult and the juvenile diet. Based on Edessa’s findings, the stated study strongly encourages the enamel oxygen and carbon isotopic signals

  10. Carbon-14 measurements in aquifers with methane

    International Nuclear Information System (INIS)

    Barker, J.F.; Fritz, P.; Brown, R.M.

    1979-01-01

    A survey of various groundwater systems indicates that methane is a common trace constituent and occasionally a major carbon species in groundwaters. Thermocatalytic methane had delta 13 Csub(CH 4 )>-45 per mille and microbially produced or biogenic methane had delta 13 Csub(CH 4 ) 13 C values for the inorganic carbon. Thermocatalytic methane had no apparent effect on the inorganic carbon. Because methanogenesis seriously affects the carbon isotope geochemistry of groundwaters, the correction of raw 14 C ages of affected groundwaters must consider these effects. Conceptual models are developed which adjust the 14 C activity of the groundwater for the effects of methanogenesis and for the dilution of carbon present during infiltration by simple dissolution of rock carbonate. These preliminary models are applied to groundwaters from the Alliston sand aquifer where methanogenesis has affected most samples. In this system, methanogenic bacteria using organic matter present in the aquifer matrix as substrate have added inorganic carbon to the groundwater which has initiated further carbonate rock dissolution. These processes have diluted the inorganic carbon 14 C activity. The adjusted groundwater ages can be explained in terms of the complex hydrogeology of this aquifer, but also indicate that these conceptual models must be more rigorously tested to evaluate their appropriateness. (author)

  11. Measurement of carbon activity in sodium and steel and the behaviour of carbon-bearing species

    International Nuclear Information System (INIS)

    Rajendran Pillai, S.; Ranganathan, R.; Mathews, C.K.

    1988-01-01

    Carburization or decarburization of structural materials in a sodium system depends on the local differences in carbon activity. The behaviour of carbon-bearing species in sodium influences its carbon activity. In order to understand the behaviour of carbon in these systems, an electrochemical carbon meter was fabricated in our laboratory. The original version of this meter was capable of operating in the temperature range of 850-980 K. Studies are carried out to extend this lower limit of temperature. Employing the carbon meter, experiments were carried out to understand the behaviour of carbon-bearing species. Gas equilibration experiments were also carried out with the same view. A new method for measuring the carbon activity in steels are described which employs the carbon meter. A review on these investigations and the conclusions reached on the behaviour of carbon in fast reactor loops are described

  12. Stable carbon and oxygen isotope signatures in molluscan shells under ocean acidification

    Science.gov (United States)

    Nishida, K.; Hayashi, M.; Suzuki, A.; Sato, M.; Nojiri, Y.

    2017-12-01

    Stable carbon and oxygen isotope compositions (δ13C, δ18O) of biogenic carbonate have been widely used for many paleoclimate, paleoecological, and biomineralization studies. δ13C of molluscan shells reflects the mixing of δ13C of dissolved inorganic carbon (DIC) of seawater and respiratory carbon. Previous studies reported physiological effects on molluscs by ocean acidification, and thus the metabolic changes could potentially appear in shell δ13C as changes in a fraction of two carbon sources. In addition, shell δ18O, a commonly used proxy of seawater temperature and seawater δ18O, is also affected by seawater carbonate chemistry. As changes in the marine carbonate system, such as pH and pCO2, have occurred in the past 300 million years, to estimate pH effect on paleotemperature reconstruction is important. Here, we experimentally examined acidification effects on shell δ13C and δ18O of two species of clams for understanding of environmental and physiological proxies. Juvenile specimens of bloody clam Scapharca broughtonii and Japanese surf clam Pseudocardium sachalinense were cultured at five (400, 600, 800, 1000, and 1200 µatm, P. sachalinense) or six (280, 400, 600, 800, 1000, and 1200 µatm, S. broughtonii) different pCO2 levels using CO2 control system of the Demonstration Laboratory, MERI, Japan. Significant negative correlations between shell δ13C and pH appeared in S. broughtonii, which showed non-significant pH effects on calcification, and the slope of the relationship of shell carbonate was lower than that of seawater DIC. On the other hand, in P. sachalinense which showed a decrease in calcification at low-pH treatment, the slopes of the relationship between shell δ13C and pH was roughly the same as that of seawater DIC. Thus, the extrapallial fluid of P. sachalinense might more strongly affected by acidified seawater than S. broughtonii. The results of two species might be attributable to differences in physiological responses to

  13. Seasonal carbonate chemistry covariation with temperature, oxygen, and salinity in a fjord estuary: implications for the design of ocean acidification experiments.

    Directory of Open Access Journals (Sweden)

    Jonathan C P Reum

    Full Text Available Carbonate chemistry variability is often poorly characterized in coastal regions and patterns of covariation with other biologically important variables such as temperature, oxygen concentration, and salinity are rarely evaluated. This absence of information hampers the design and interpretation of ocean acidification experiments that aim to characterize biological responses to future pCO2 levels relative to contemporary conditions. Here, we analyzed a large carbonate chemistry data set from Puget Sound, a fjord estuary on the U.S. west coast, and included measurements from three seasons (winter, summer, and fall. pCO2 exceeded the 2008-2011 mean atmospheric level (392 µatm at all depths and seasons sampled except for the near-surface waters (< 10 m in the summer. Further, undersaturated conditions with respect to the biogenic carbonate mineral aragonite were widespread (Ωar<1. We show that pCO2 values were relatively uniform throughout the water column and across regions in winter, enriched in subsurface waters in summer, and in the fall some values exceeded 2500 µatm in near-surface waters. Carbonate chemistry covaried to differing levels with temperature and oxygen depending primarily on season and secondarily on region. Salinity, which varied little (27 to 31, was weakly correlated with carbonate chemistry. We illustrate potential high-frequency changes in carbonate chemistry, temperature, and oxygen conditions experienced simultaneously by organisms in Puget Sound that undergo diel vertical migrations under present-day conditions. We used simple calculations to estimate future pCO2 and Ωar values experienced by diel vertical migrators based on an increase in atmospheric CO2. Given the potential for non-linear interactions between pCO2 and other abiotic variables on physiological and ecological processes, our results provide a basis for identifying control conditions in ocean acidification experiments for this region, but also highlight

  14. Oxygen plasma assisted end-opening and field emission enhancement in vertically aligned multiwall carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mathur, A. [NIBEC, School of Engineering, University of Ulster, Jordanstown, BT37 0QB (United Kingdom); Roy, S.S., E-mail: sinharoy@ualberta.ca [Department of Mechanical Engineering, University of Alberta, Edmonton, T6T 2G8 (Canada); Hazra, K.S. [Department of Physics, IIT Bombay, Powai, Mumbai-400076 (India); Wadhwa, S. [NIBEC, School of Engineering, University of Ulster, Jordanstown, BT37 0QB (United Kingdom); Ray, S.C. [School of Physics, University of the Witwatersrand, WITS 2050, Johannesburg (South Africa); Mitra, S.K. [Department of Mechanical Engineering, University of Alberta, Edmonton, T6T 2G8 (Canada); Misra, D.S. [Department of Physics, IIT Bombay, Powai, Mumbai-400076 (India); McLaughlin, J.A. [NIBEC, School of Engineering, University of Ulster, Jordanstown, BT37 0QB (United Kingdom)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer We showed Ar/O{sub 2} plasma can be effective for the end opening of aligned CNTs. Black-Right-Pointing-Pointer The field emission property was dramatically enhanced after plasma modification. Black-Right-Pointing-Pointer Microstructures were clearly understood by Raman and SEM analysis. Black-Right-Pointing-Pointer Surface wet-ability at various functionalised conditions was studied. - Abstract: This paper highlights the changes in micro-structural and field emission properties of vertically aligned carbon nanotubes (VACNTs) via oxygen plasma treatment. We find that exposure of very low power oxygen plasma (6 W) at 13.56 MHz for 15-20 min, opens the tip of vertically aligned CNTs. Scanning electron microscopy and transmission electron microscopy images were used to identify the quality and micro-structural changes of the nanotube morphology and surfaces. Raman spectra showed that the numbers of defects were increased throughout the oxygen plasma treatment process. In addition, the hydrophobic nature of the VACNTs is altered significantly and the contact angle decreases drastically from 110 Degree-Sign to 40 Degree-Sign . It was observed that the electron field emission (EFE) characteristics are significantly enhanced. The turn-on electric field (ETOE) of CNTs decreased from {approx}0.80 V {mu}m{sup -1} (untreated) to {approx}0.60 V {mu}m{sup -1} (oxygen treated). We believe that the open ended VACNTs would be immensely valuable for applications such as micro/nanofluidic based filtering elements and display devices.

  15. Adsorption of volatile sulphur compounds onto modified activated carbons: Effect of oxygen functional groups

    International Nuclear Information System (INIS)

    Vega, Esther; Lemus, Jesús; Anfruns, Alba; Gonzalez-Olmos, Rafael; Palomar, José; Martin, María J.

    2013-01-01

    Highlights: • HNO 3 oxidation incorporates a higher amount of functionalities than O 3 oxidation. • The loss of porosity is compensated by the massive incorporation of oxygen groups. • HNO 3 oxidation increases OH groups in AC and the ETM and DMS adsorption capacities. • The oxygen functional groups in the AC surface did not affect the DMDS adsorption. • COSMO-RS predicts the important role of OH groups for VSC adsorption. -- Abstract: The effect of physical and chemical properties of activated carbon (AC) on the adsorption of ethyl mercaptan, dimethyl sulphide and dimethyl disulphide was investigated by treating a commercial AC with nitric acid and ozone. The chemical properties of ACs were characterised by temperature programme desorption and X-ray photoelectron spectroscopy. AC treated with nitric acid presented a larger amount of oxygen functional groups than materials oxidised with ozone. This enrichment allowed a significant improvement on adsorption capacities for ethyl mercaptan and dimethyl sulphide but not for dimethyl disulphide. In order to gain a deeper knowledge on the effect of the surface chemistry of AC on the adsorption of volatile sulphur compounds, the quantum-chemical COSMO-RS method was used to simulate the interactions between AC surface groups and the studied volatile sulphur compounds. In agreement with experimental data, this model predicted a greater affinity of dimethyl disulphide towards AC, unaffected by the incorporation of oxygen functional groups in the surface. Moreover, the model pointed out to an increase of the adsorption capacity of AC by the incorporation of hydroxyl functional groups in the case of ethyl mercaptan and dimethyl sulphide due to the hydrogen bond interactions

  16. Adsorption of volatile sulphur compounds onto modified activated carbons: Effect of oxygen functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Vega, Esther, E-mail: esther@lequia.udg.cat [LEQUIA, Institute of the Environment, University of Girona, Campus Montilivi, Girona, Catalonia E-17071 (Spain); Lemus, Jesús [Universidad de Madrid, Sección de Ingeniería Química, Cantoblanco, Madrid E-28049 (Spain); Anfruns, Alba; Gonzalez-Olmos, Rafael [LEQUIA, Institute of the Environment, University of Girona, Campus Montilivi, Girona, Catalonia E-17071 (Spain); Palomar, José [Universidad de Madrid, Sección de Ingeniería Química, Cantoblanco, Madrid E-28049 (Spain); Martin, María J. [LEQUIA, Institute of the Environment, University of Girona, Campus Montilivi, Girona, Catalonia E-17071 (Spain)

    2013-08-15

    Highlights: • HNO{sub 3} oxidation incorporates a higher amount of functionalities than O{sub 3} oxidation. • The loss of porosity is compensated by the massive incorporation of oxygen groups. • HNO{sub 3} oxidation increases OH groups in AC and the ETM and DMS adsorption capacities. • The oxygen functional groups in the AC surface did not affect the DMDS adsorption. • COSMO-RS predicts the important role of OH groups for VSC adsorption. -- Abstract: The effect of physical and chemical properties of activated carbon (AC) on the adsorption of ethyl mercaptan, dimethyl sulphide and dimethyl disulphide was investigated by treating a commercial AC with nitric acid and ozone. The chemical properties of ACs were characterised by temperature programme desorption and X-ray photoelectron spectroscopy. AC treated with nitric acid presented a larger amount of oxygen functional groups than materials oxidised with ozone. This enrichment allowed a significant improvement on adsorption capacities for ethyl mercaptan and dimethyl sulphide but not for dimethyl disulphide. In order to gain a deeper knowledge on the effect of the surface chemistry of AC on the adsorption of volatile sulphur compounds, the quantum-chemical COSMO-RS method was used to simulate the interactions between AC surface groups and the studied volatile sulphur compounds. In agreement with experimental data, this model predicted a greater affinity of dimethyl disulphide towards AC, unaffected by the incorporation of oxygen functional groups in the surface. Moreover, the model pointed out to an increase of the adsorption capacity of AC by the incorporation of hydroxyl functional groups in the case of ethyl mercaptan and dimethyl sulphide due to the hydrogen bond interactions.

  17. Oxygen Pickup Ions Measured by MAVEN Outside the Martian Bow Shock

    Science.gov (United States)

    Rahmati, A.; Cravens, T.; Larson, D. E.; Lillis, R. J.; Dunn, P.; Halekas, J. S.; Connerney, J. E. P.; Eparvier, F. G.; Thiemann, E.; Mitchell, D. L.; Jakosky, B. M.

    2015-12-01

    The MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft entered orbit around Mars on September 21, 2014 and has since been detecting energetic oxygen pickup ions by its SEP (Solar Energetic Particles) and SWIA (Solar Wind Ion Analyzer) instruments. The oxygen pickup ions detected outside the Martian bowshock and in the upstream solar wind are associated with the extended hot oxygen exosphere of Mars, which is created mainly by the dissociative recombination of molecular oxygen ions with electrons in the ionosphere. We use analytic solutions to the equations of motion of pickup ions moving in the undisturbed upstream solar wind magnetic and motional electric fields and calculate the flux of oxygen pickup ions at the location of MAVEN. Our model calculates the ionization rate of oxygen atoms in the exosphere based on the hot oxygen densities predicted by Rahmati et al. (2014), and the sources of ionization include photo-ionization, charge exchange, and electron impact ionization. The photo-ionization frequency is calculated using the FISM (Flare Irradiance Spectral Model) solar flux model, based on MAVEN EUVM (Extreme Ultra-Violet Monitor) measurements. The frequency of charge exchange between a solar wind proton and an oxygen atom is calculated using MAVEN SWIA solar wind proton flux measurements, and the electron impact ionization frequency is calculated based on MAVEN SWEA (Solar Wind Electron Analyzer) solar wind electron flux measurements. The solar wind magnetic field used in the model is from the measurements taken by MAVEN MAG (magnetometer) in the upstream solar wind. The good agreement between our predicted pickup oxygen fluxes and the MAVEN SEP and SWIA measured ones confirms detection of oxygen pickup ions and these model-data comparisons can be used to constrain models of hot oxygen densities and photochemical escape flux.

  18. ESR study on the interaction between carbon blacks and oxygen molecules; ESR ho ni yoru carbon black to sanso bunshi tono sogo sayo no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Okazaki, M.; Toriyama, K.; Konishi, Y. [National Industrial Research Institute of Nagoya, Nagoya (Japan)

    2000-02-24

    Interaction between carbon blacks and oxygen molecules has been studied by means of electron spin resonance (ESR) spectroscopy. The ESR spectra of the carbon blacks appears at the g-value of free spin, which are contributed by both isolated electrons and conduction electrons. Upon introducing oxygen to the system the ESR linewidth was broadened in proportion to the partial pressure of oxygen. In case of lampblack (LB 101, Degussa) the interaction was not so strong that it took a tong time at 77K for the linewidth to reach the maxmum value. In case of gassblack (P 140 V, Degussa), on the other hand, the oxygen was easily adsorbed at 298K and the linewidth at 77K became its maximum immediately after cooling. The number of unpaired electrons decreased when the system was kept at 298 K and the decrease was prominent for the local spins. These phenomena have been explained with a simple band model for the electron. (author)

  19. Synthesis and characterization of carbon supported PdNi nanocatalysts for electroreduction of oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Muhammad Sufaid; Milian, Rosendo Parra, E-mail: sufaidkhan1984@gmail.com [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil). Instituto de Química; Gallo, Irã Borges Coutinho; Villullas, Hebe Mercedes [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Sao Paulo, SP (Brazil). Instituto de Química

    2016-07-01

    Full text: In this work, PdNi nanoparticles were prepared by a modified polyol method [1] with different Pd:Ni nominal ratios (80:20, 70:30 and 50:50, in atoms) and then supported on carbon (Vulcan XC-72). The structural properties of all materials were characterized by X-ray diffraction (XRD). Data show the formation PdNi alloys, as indicated by the decreased of the Pd lattice parameter compared Pd/C. The Pd 4d band electronic occupancy was assessed by X-ray Absorption Spectroscopy measurements that were carried out around the Pd L3 edge. Results evidenced that the presence of Ni decreases the electronic vacancy of the Pd 4d band. The electrocatalytic activity for the oxygen reduction reaction (ORR) was studied using the rotating disk electrode technique in O{sub 2}-saturated H{sub 2}SO{sub 4} and NaOH solutions. Overall, all PdNi materials presented better catalytic performance for the ORR than pure Pd, in both acidic and alkaline media. The production of H{sub 2}O{sub 2} was quantified using the rotating ring-disk technique, which allowed detecting this reaction intermediate by oxidizing it at the ring electrode. In all cases, data indicate low production of H{sub 2}O{sub 2}, which suggests that the ORR occurs mainly through the 4 electron mechanism on all catalysts studied in this work. Additionally, all prepared materials were submitted to stability tests by continuous potential cycling up to 1.0 V (vs. RHE). These studies evidenced that stability of Pd against dissolution is affected by the presence of Ni, with significant improvement for the PdNi alloys containing 20 and 30% Ni. Acknowledgments. Thanks are due to FAPESP (2014/12255-6) and CNPq (407143/2013-0) for financial support, and to the Brazilian Synchrotron Light Laboratory (LNLS) for the XAS experiments. References [1] S. Sun, C.B. Murray, D. Weller, L. Folks, A. Moser. Science 287, 1989 (2000). (author)

  20. Kinetics of Several Oxygen-Containing Carbon-Centered Free Radical Reactions with Nitric Oxide.

    Science.gov (United States)

    Rissanen, Matti P; Ihlenborg, Marvin; Pekkanen, Timo T; Timonen, Raimo S

    2015-07-16

    Kinetics of four carbon-centered, oxygen-containing free radical reactions with nitric oxide (NO) were investigated as a function of temperature at a few Torr pressure of helium, employing flow tube reactors coupled to a laser-photolysis/resonance-gas-discharge-lamp photoionization mass spectrometer (LP-RPIMS). Rate coefficients were directly determined from radical (R) decay signals under pseudo-first-order conditions ([R]0 ≪ [NO]). The obtained rate coefficients showed negative temperature dependences, typical for a radical-radical association process, and can be represented by the following parametrizations (all in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO) = (4.76 × 10(-21)) × (T/300 K)(15.92) × exp[50700/(RT)] (T = 266-363 K, p = 0.79-3.44 Torr); k(CH3CHOH + NO) = (1.27 × 10(-16)) × (T/300 K)(6.81) × exp[28700/(RT)] (T = 241-363 K, p = 0.52-3.43 Torr); k(CH3OCH2 + NO) = (3.58 ± 0.12) × 10(-12) × (T/300 K)(-3.17±0.14) (T = 221-363 K, p = 0.50-0.80 Torr); k(T)3 = 9.62 × 10(-11) × (T/300 K)(-5.99) × exp[-7100/(RT)] (T = 221-473 K, p = 1.41-2.95 Torr), with the uncertainties given as standard errors of the fits and the overall uncertainties estimated as ±20%. The rate of CH3OCH2 + NO reaction was measured in two density ranges due to its observed considerable pressure dependence, which was not found in the studied hydroxyalkyl reactions. In addition, the CH3CO + NO rate coefficient was determined at two temperatures resulting in k298K(CH3CO + NO) = (5.6 ± 2.8) × 10(-13) cm(3) molecule(-1) s(-1). No products were found during these experiments, reasons for which are briefly discussed.

  1. Kinetics of several oxygenated carbon-centered free radical reactions with NO2.

    Science.gov (United States)

    Rissanen, Matti P; Arppe, Suula L; Timonen, Raimo S

    2013-05-16

    Five oxygenated carbon-centered free radical reactions with nitrogen dioxide (NO2) have been studied in direct time-resolved measurements. Experiments were conducted in a temperature-controlled flow tube reactor coupled to a 193 nm exciplex laser photolysis and a resonance gas lamp photoionization mass spectrometer. Reactions were investigated under pseudofirst-order conditions, with the NO2 concentrations of the experiments in great excess over the initial radical concentrations ([R]0 CH3CO radical reactions with NO2 and, hence, includes the three smallest hydroxyalkyl radical species (CH2OH, CH2CH2OH, and CH3CHOH). The obtained rate coefficients are high with the temperature-dependent rate coefficients given by a formula k(T) = k300K × (T/300 K)(-n) as (in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO2) = (8.95 ± 2.70) × 10(-11) × (T/300 K)(-0.54±0.27) (T = 298-363 K), k(CH2CH2OH + NO2) = (5.99 ± 1.80) × 10(-11) × (T/300 K)(-1.49±0.45)(T = 241-363 K), k(CH3CHOH + NO2) = (7.48 ± 2.24) × 10(-11) × (T/300 K)(-1.36±0.41) (T = 266-363 K), k(CH3OCH2 + NO2) = (7.85 ± 2.36) × 10(-11) × (T/300 K)(-0.93±0.28) (T = 243-363 K), and k(CH3CO + NO2) = (2.87 ± 0.57) × 10(-11) × (T/300 K)(-2.45±0.49) (T = 241-363 K), where the uncertainties refer to the estimated overall uncertainties of the values obtained. The determined rate coefficients show negative temperature dependence with no apparent bath gas pressure dependence under the current experimental conditions (241-363 K and about 1-3 Torr helium). This behavior is typical for a radical-radical addition mechanism with no potential energy barrier above the energy of the separated reactants in the entrance channel of the reaction. Unfortunately the absence of detected product signals prevented gaining deeper insight into the reaction mechanism.

  2. The influence of oxygen and carbon dioxide on diving behaviour of tufted ducks, Aythya fuligula.

    Science.gov (United States)

    Halsey, Lewis; Reed, Jane Z; Woakes, Anthony; Butler, Patrick

    2003-01-01

    While optimal diving models focus on the diver's oxygen (O(2)) stores as the predominant factor influencing diving behaviour, many vertebrate species surface from a dive before these stores are exhausted and may commence another dive well after their O(2) stores have been resaturated. This study investigates the influence of hypoxia and also hypercapnia on the dive cycle of tufted ducks, Aythya fuligula, in terms of surface duration and dive duration. The birds were trained to surface into a respirometer box after each dive to a feeding tray so that rates of O(2) uptake (VO2) and carbon dioxide output (VCO2) at the surface could be measured. Although Vco2 initially lagged behind Vo2, both respiratory gas stores were close to full adjustment after the average surface duration, indicating that they probably had a similar degree of influence on surface duration. Chemoreceptors, which are known to influence diving behaviour, detect changes in O(2) and CO(2) partial pressures in the arterial blood. Thus, the need to restore blood gas levels appears to be a strong stimulus to continue ventilation. Mean surface duration coincided with peak instantaneous respiratory exchange ratio due to predive anticipatory hyperventilation causing hypocapnia. For comparison, the relationship between surface duration and O(2) uptake in reanalysed data for two grey seals indicated that one animal tended to dive well after fully restocking its O(2) stores, while the other dived at the point of full restocking. More CO(2) is exchanged than O(2) in tufted ducks during the last few breaths before the first dive of a bout, serving to reduce CO(2) stores and suggesting that hypercapnia rather than hypoxia is more often the limiting factor on asphyxia tolerance during dives. Indeed, according to calculations of O(2) stores and O(2) consumption rates over modal diving durations, a lack of O(2) does not seem to be associated with the termination of a dive in tufted ducks. However, factors other

  3. Ordered hierarchically porous carbon codoped with iron and nitrogen as electrocatalyst for the oxygen reduction reaction.

    Science.gov (United States)

    Deng, Chengwei; Zhong, Hexiang; Yao, Lan; Liu, Sisi; Xu, Zhuang; Zhang, Huamin

    2014-12-01

    N-doped carbon catalysts have attracted great attention as potential alternatives to expensive Pt-based catalysts used in fuel cells. Herein, an ordered hierarchically porous carbon codoped with N and Fe (Fe-NOHPC) is prepared by an evaporation-induced self-assembly process followed by carbonization under ammonia. The soft template and Fe species promote the formation of the porous structure and facilitate the oxygen reduction reaction (ORR).The catalyst possesses an ordered hierarchically porous structure with a large surface area (1172.5 m(2) g(-1) ) and pore volume of 1.03 cm(3) g(-1) . Compared to commercial 20% Pt/C, it exhibits better ORR catalytic activity and higher stability as well as higher methanol tolerance in an alkaline electrolyte, which demonstrates its potential use in fuel cells as a nonprecious cathode catalyst. The N configuration, Fe species, and pore structure of the catalysts are believed to correlate with its high catalytic activity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Nitrogen and Fluorine-Codoped Carbon Nanowire Aerogels as Metal-Free Electrocatalysts for Oxygen Reduction Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Shaofang [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Zhu, Chengzhou [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Song, Junhua [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Engelhard, Mark H. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99352 USA; Xiao, Biwei [Energy and Environmental Directory, Pacific Northwest National Laboratory, Richland WA 99352 USA; Du, Dan [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Lin, Yuehe [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA

    2017-07-11

    The development of active, durable, and low-cost catalysts to replace noble metal-based materials is highly desirable to promote the sluggish oxygen reduction reaction in fuel cells. Herein, nitrogen and fluorine-codoped three-dimensional carbon nanowire aerogels, composed of interconnected carbon nanowires, were synthesized for the first time by a hydrothermal carbonization process. Owing to their porous nanostructures and heteroatom-doping, the as-prepared carbon nanowire aerogels, with optimized composition, present excellent electrocatalytic activity that is comparable to commercial Pt/C. Remarkably, the aerogels also exhibit superior stability and methanol tolerance. This synthesis procedure paves a new way to design novel heteroatomdoped catalysts.

  5. Partial pressure of carbon dioxide, pH, oxygen and other variables collected from time series observations using SAMI-CO2, SAMI-pH, and other instruments from Buoy NH-10 off the coast of Newport, Oregon, United States, at the near bottom depth of ~80 meters from 2011-08-16 to 2015-08-25 (NCEI Accession 0145162)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains time series measurements of near bottom partial pressure of carbon dioxide, pH, dissolved oxygen that are measured from SAMI-CO2, and...

  6. 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

  7. Effects of nitrogen- and oxygen-containing functional groups of activated carbon nanotubes on the electrochemical performance in supercapacitors

    Science.gov (United States)

    Liu, Haiyan; Song, Huaihe; Chen, Xiaohong; Zhang, Su; Zhou, Jisheng; Ma, Zhaokun

    2015-07-01

    A kind of nitrogen- and oxygen-containing activated carbon nanotubes (ACNTs) has been prepared by carbonization and activation of polyaniline nanotubes obtained by rapidly mixed reaction. The ACNTs show oxygen content of 15.7% and nitrogen content of 2.97% (atomic ratio). The ACNTs perform high capacitance and good rate capability (327 F g-1 at the current density of 10 A g-1) when used as the electrode materials for supercapacitors. Hydrogen reduction has been further used to investigate the effects of surface functional groups on the electrochemical performance. The changes for both structural component and electrochemical performance reveal that the quinone oxygen, pyridinic nitrogen, and pyrrolic nitrogen of carbon have the most obvious influence on the capacitive property because of their pseudocapacitive contributions.

  8. Preliminary study on the characteristics of carbon and oxygen isotopes in the Shiziping geothermal field groundwater in Emei Mountain

    International Nuclear Information System (INIS)

    Yu Xiujing; Jia Shuyuan

    2000-01-01

    Emei Mountain is a well-known scenic tourism spot in China. In order to promote the development of tourist trade, the authors have explored the hydrothermal water in Emei Mountain. At the beginning of 1998, the hydrothermal water was successfully drilled from the Shiziping geothermal field. In the process of prospecting the hydrothermal water, the authors adopted the geochemical method such as carbon and oxygen isotopes. The result indicates that the groundwater of different genetic types has different constitution characteristics of carbon and oxygen isotopes. This provides the important basis for finding out the forming conditions of underground hydrothermal water. So, it is prospective to study the growth characteristics of hydrothermal water with the carbon and oxygen isotopes of HCO 3 in groundwater

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  10. About Error in Measuring Oxygen Concentration by Solid-Electrolyte Sensors

    Directory of Open Access Journals (Sweden)

    V. I. Nazarov

    2008-01-01

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

  11. Definition, significance and measurement of quantities pertaining to the oxygen carrying properties of human blood

    NARCIS (Netherlands)

    Zijlstra, WG; Maas, AHJ; Moran, RF

    1996-01-01

    A consistent set of definitions is given of the principal quantities pertaining to the oxygen transport by the blood, and of their mutual relationships, in relation to the methods used in their measurement. At the core is the correct definition of oxygen saturation, the deviation of which has

  12. Microwave assisted synthesis of camellia oleifera shell-derived porous carbon with rich oxygen functionalities and superior supercapacitor performance

    Science.gov (United States)

    Liang, Jiyuan; Qu, Tingting; Kun, Xiang; Zhang, Yu; Chen, Shanyong; Cao, Yuan-Cheng; Xie, Mingjiang; Guo, Xuefeng

    2018-04-01

    Biomass-derived carbon (BDCs) materials are receiving extensive attention as electrode materials for energy storage because of the considerable economic value offering possibility for practical applications, but the electrochemical capacitance of BDCs are usually relatively low resulted from limited electric double layer capacitance. Herein, an oxygen-rich porous carbon (KMAC) was fabricated through a rapid and convenient microwave assisted carbonization and KOH activation of camellia oleifera shell. The obtained KMAC possesses three-dimensional porous architecture, large surface area (1229 m2/g) and rich oxygen functionalities (C/O ratio of 1.66). As the electrode materials for supercapacitor, KMAC exhibits superior supercapacitive performances as compared to the activated carbon (KAC) derived from direct carbonization/KOH activation method in 2.0 M H2SO4 (315 F/g vs. 202 F/g) and 6.0 M KOH (251 F/g vs. 214 F/g) electrolyte due to the rich oxygen-containing functional groups on the surface of porous carbon resulted from the developed microwave-assisted carbonization/activation approach.

  13. The influence of carbon and oxygen on the magnetic characteristics of press-less sintered NdFeB magnets

    International Nuclear Information System (INIS)

    Xia, M.; Abrahamsen, A.B.; Bahl, C.R.H.; Veluri, B.; Søegaard, A.I.; Bøjsøe, P.; Millot, S.

    2017-01-01

    The Pressless Process (PLP) was adopted to manufacture NdFeB sintered magnets, where the investigations on carbon and oxygen residues from heptane milling liquid media and graphite crucibles used for sintering were quantified to evaluate the influence on the magnetic characteristics. The carbon and oxygen content in the magnets produced from wet ball milling of strip cast flakes was found to be of the order 10 4 ppm and 4·10 4 ppm respectively, which resulted in soft magnetic behavior. However using jet milling the carbon and oxygen concentration were decreased by an order of magnitude resulting in coercivity of up to 829 kA/m. Thus the influence of the carbon from the graphite crucibles is small. - Highlights: • It is found that the carbon from graphite crucibles will not influence the NdFeB. • The carbon from heptane mixed with NdFeB powder will react with the NdFeB, which breaks the magnetic properties of NdFeB. • Pressless process works well with graphite crucibles, without worrying that carbon has damage on magnets.

  14. The influence of carbon and oxygen on the magnetic characteristics of press-less sintered NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Xia, M., E-mail: maxi@dtu.dk [Department of Energy Conversion and Storage, DTU Risø Campus, Technical University of Denmark, Roskilde (Denmark); Abrahamsen, A.B. [Department of Wind Energy, DTU Risø campus, Technical University of Denmark, Roskilde (Denmark); Bahl, C.R.H. [Department of Energy Conversion and Storage, DTU Risø Campus, Technical University of Denmark, Roskilde (Denmark); Veluri, B.; Søegaard, A.I. [Grundfos A/S, DK-8850 Bjerringbro (Denmark); Bøjsøe, P. [Holm Magnetics APS, 2800 Kongens Lyngby (Denmark); Millot, S. [FJ Industries A/S, 5863 Ferritslev (Denmark)

    2017-01-15

    The Pressless Process (PLP) was adopted to manufacture NdFeB sintered magnets, where the investigations on carbon and oxygen residues from heptane milling liquid media and graphite crucibles used for sintering were quantified to evaluate the influence on the magnetic characteristics. The carbon and oxygen content in the magnets produced from wet ball milling of strip cast flakes was found to be of the order 10{sup 4} ppm and 4·10{sup 4} ppm respectively, which resulted in soft magnetic behavior. However using jet milling the carbon and oxygen concentration were decreased by an order of magnitude resulting in coercivity of up to 829 kA/m. Thus the influence of the carbon from the graphite crucibles is small. - Highlights: • It is found that the carbon from graphite crucibles will not influence the NdFeB. • The carbon from heptane mixed with NdFeB powder will react with the NdFeB, which breaks the magnetic properties of NdFeB. • Pressless process works well with graphite crucibles, without worrying that carbon has damage on magnets.

  15. Oscillator-strength distributions for oxygen, carbon dioxide, water, methyl chloride, and carbon tetrachloride

    International Nuclear Information System (INIS)

    Person, J.C.; Nicole, P.P.

    1979-01-01

    New measurements of photoabsorption give oscillator-strength values for the following gases and energy regions: O 2 , 7.34 to 11.79 eV; CO 2 , 7.34 to 11.77 eV; H 2 O, 6.62 to 11.80 eV; CH 3 CL, 6.14 to 11.25 eV; and CCl 4 , 6.14 to 11.49 eV. Comparisons are made with some values from the literature

  16. Mid-depth respired carbon storage and oxygenation of the eastern equatorial Pacific over the last 25,000 years

    Science.gov (United States)

    Umling, Natalie E.; Thunell, Robert C.

    2018-06-01

    A growing body of evidence suggests that respired carbon was stored in mid-depth waters (∼1-3 km) during the last glacial maximum (LGM) and released to the atmosphere from upwelling regions during deglaciation. Decreased ventilation, enhanced productivity, and enhanced carbonate dissolution are among the mechanisms that have been cited as possible drivers of glacial CO2 drawdown. However, the relative importance of each of these mechanisms is poorly understood. New approaches to quantitatively constrain bottom water carbonate chemistry and oxygenation provide methods for estimating historic changes in respired carbon storage. While increased CO2 drawdown during the LGM should have resulted in decreased oxygenation and a shift in dissolved inorganic carbon (DIC) speciation towards lower carbonate ion concentrations, this is complicated by the interplay of carbonate compensation, export productivity, and circulation. To disentangle these processes, we use a multiproxy approach that includes boron to calcium (B/Ca) ratios of the benthic foraminifera Cibicidoides wuellerstorfi to reconstruct deep-water carbonate ion concentrations ([CO32-]) and the uranium to calcium (U/Ca) ratio of foraminiferal coatings in combination with benthic foraminiferal carbon isotopes to reconstruct changes in bottom water oxygen concentrations ([O2]) and organic carbon export. Our records indicate that LGM [CO32-] and [O2] was reduced at mid water depths of the eastern equatorial Pacific (EEP), consistent with increased respired carbon storage. Furthermore, our results suggest enhanced mixing of lower Circumpolar Deep Water (LCDW) to EEP mid water depths and provide evidence for the importance of circulation for oceanic-atmospheric CO2 exchange.

  17. 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

  18. Carbon Dioxide Fluctuations Are Associated with Changes in Cerebral Oxygenation and Electrical Activity in Infants Born Preterm.

    Science.gov (United States)

    Dix, Laura Marie Louise; Weeke, Lauren Carleen; de Vries, Linda Simone; Groenendaal, Floris; Baerts, Willem; van Bel, Frank; Lemmers, Petra Maria Anna

    2017-08-01

    To evaluate the effects of acute arterial carbon dioxide partial pressure changes on cerebral oxygenation and electrical activity in infants born preterm. This retrospective observational study included ventilated infants born preterm with acute fluctuations of continuous end-tidal CO 2 (etCO 2 ) as a surrogate marker for arterial carbon dioxide partial pressure, during the first 72 hours of life. Regional cerebral oxygen saturation and fractional tissue oxygen extraction were monitored with near-infrared spectroscopy. Brain activity was monitored with 2-channel electroencephalography. Spontaneous activity transients (SATs) rate (SATs/minute) and interval between SATs (in seconds) were calculated. Ten-minute periods were selected for analysis: before, during, and after etCO 2 fluctuations of ≥5  mm Hg. Thirty-eight patients (mean ± SD gestational age of 29 ± 1.8 weeks) were included, with 60 episodes of etCO 2 increase and 70 episodes of etCO 2 decrease. During etCO 2 increases, brain oxygenation increased (regional cerebral oxygen saturation increased, fractional tissue oxygen extraction decreased; P carbon dioxide partial pressure that may be harmful to the neonatal brain. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Facilitated Oxygen Chemisorption in Heteroatom-Doped Carbon for Improved Oxygen Reaction Activity in All-Solid-State Zinc-Air Batteries.

    Science.gov (United States)

    Liu, Sisi; Wang, Mengfan; Sun, Xinyi; Xu, Na; Liu, Jie; Wang, Yuzhou; Qian, Tao; Yan, Chenglin

    2018-01-01

    Driven by the intensified demand for energy storage systems with high-power density and safety, all-solid-state zinc-air batteries have drawn extensive attention. However, the electrocatalyst active sites and the underlying mechanisms occurring in zinc-air batteries remain confusing due to the lack of in situ analytical techniques. In this work, the in situ observations, including X-ray diffraction and Raman spectroscopy, of a heteroatom-doped carbon air cathode are reported, in which the chemisorption of oxygen molecules and oxygen-containing intermediates on the carbon material can be facilitated by the electron deficiency caused by heteroatom doping, thus improving the oxygen reaction activity for zinc-air batteries. As expected, solid-state zinc-air batteries equipped with such air cathodes exhibit superior reversibility and durability. This work thus provides a profound understanding of the reaction principles of heteroatom-doped carbon materials in zinc-air batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Industrial compatible re-growth of vertically aligned multiwall carbon nanotubes by ultrafast pure oxygen purification process

    DEFF Research Database (Denmark)

    Bu, Ian Y.Y.; Hou, Kai; Engstrøm, Daniel Southcott

    2011-01-01

    amorphous carbon and reactivate nickel catalyst. Controlling of the purification temperature is important for high yield CNTs, as excessive high annealing temperature results in deformation of the CNTs. Unlike hazardous wet purification treatments, purified CNTs remained vertically aligned and offer......Reproducible high-yield purification process of multiwalled carbon nanotubes (CNTs) was developed by thermal annealing in ultrapure oxygen. The optimized condition involves thermal annealing via a PID controlled heater in high purity oxygen at temperature of 450°C for 180s, which burns out...

  1. Carbon, nitrogen and oxygen isotope fractionation during food cooking: Implications for the interpretation of the fossil human record.

    Science.gov (United States)

    Royer, Aurélien; Daux, Valérie; Fourel, François; Lécuyer, Christophe

    2017-08-01

    Stable isotope data provide insight into the reconstruction of ancient human diet. However, cooking may alter the original stable isotope compositions of food due to losses and modifications of biochemical and water components. To address this issue, carbon, nitrogen and oxygen isotope ratios were measured on meat aliquots sampled from various animals such as pork, beef, duck and chicken, and also from the flesh of fishes such as salmon, European seabass, European pilchard, sole, gilt-head bream, and tuna. For each specimen, three pieces were cooked according to the three most commonly-known cooking practices: boiling, frying and roasting on a barbecue. Our data show that cooking produced isotopic shifts up to 1.8‰, 3.5‰, and 5.2‰ for δ 13 C, δ 15 N, and δ 18 O values, respectively. Such variations between raw and cooked food are much greater than previously estimated in the literature; they are more sensitive to the type of food rather than to the cooking process itself, except in the case of boiling. Reconstructions of paleodietary may thus suffer slight bias in cases of populations with undiversified diets that are restrained toward a specific raw or cooked product, or using a specific cooking mode. In cases of oxygen isotope compositions from skeletal remains (bones, teeth), they not only constitute a valuable proxy for reconstructing past climatic conditions, but they could also be used to improve our knowledge of past human diet. © 2017 Wiley Periodicals, Inc.

  2. Oxygen and Carbon Isotopic Composition of Carbonate Rocks of the Permian Qixia Formation, Sichuan Basin: Thermal Effects of Emeishan Basalt

    Directory of Open Access Journals (Sweden)

    Keke Huang

    2016-01-01

    Full Text Available The late Permian thermal events related to Emeishan Basalt has made a great impact on the underlying carbonate rock properties in the western margin of the Yangtze Platform. In this paper, we investigate the carbon and oxygen isotopic composition of the Qixia Formation carbonates from two sections: the Qiaoting Section in the northeastern part of the Sichuan Basin and the Changjianggou Section at the northwestern edge of the Basin. The data reveal that: (i Samples from Qiaoting section show a relatively narrow range of δ13C and δ18O, varying from 2.7‰ to 5.2‰ with an average of 4.2‰, and -3.8‰ to -7.8‰ with an average of -5.4‰, respectively. In contrast, Samples from Changjianggou section exhibit larger magnitude of variation in δ13C and δ18O, ranging from -1‰ to 3.8‰ with an average of 1.5‰, and -2.1 to -9.2‰, with an average of -6.0‰ respectively; (ii δ13C and δ18O records in carbonates from Qiaoting section are similar to those of Middle Permian seawater whereas carbonates from the Changjianggou section are depleted in 13C and 18O compared to contemporary seawater; (iii On the basis of combined petrographic and paleo-heat flow evidence, the lower carbon and oxygen isotopic composition of the carbonates from the Changjianggou section are interpreted to be the results of thermal effects of Emeishan Basalt because of its proximity to the eruption center of the basalt. The high temperature reduced the δ18O values of the carbonates and forced the organic matter to mature at an early stage, thus producing 13C-enriched carbon dioxide to participate in the formation of carbonates.     Composición Isotópica de Oxígeno y Carbón en Rocas de Carbonato de la Formación de Edad Pérmica Qixia, en la Cuenca de Sichuan: Efectos Térmicos del Basalto Emeishan   Resumen Los eventos térmicos del Pérmico tardío relacionados con el Basalto Emeishan han tenido un gran impacto en las propiedades de las rocas de carbonato

  3. Carbonate chemistry, water quality, coral measurements

    Data.gov (United States)

    U.S. Environmental Protection Agency — Carbonate chemistry parameters (pH, total alkalinity, and pCO2), water quality parameters (Temperature, salinity, Ca, Mg, PO4, NH3 and NO3) as well as all coral...

  4. Development of an oxygen saturation measuring system by using near-infrared spectroscopy

    Science.gov (United States)

    Kono, K.; Nakamachi, E.; Morita, Y.

    2017-08-01

    Recently, the hypoxia imaging has been recognized as the advanced technique to detect cancers because of a strong relationship with the biological characterization of cancer. In previous studies, hypoxia imaging systems for endoscopic diagnosis have been developed. However, these imaging technologies using the visible light can observe only blood vessels in gastric mucous membrane. Therefore, they could not detect scirrhous gastric cancer which accounts for 10% of all gastric cancers and spreads rapidly into submucous membrane. To overcome this problem, we developed a measuring system of blood oxygen saturation in submucous membrane by using near-infrared (NIR) spectroscopy. NIR, which has high permeability for bio-tissues and high absorbency for hemoglobin, can image and observe blood vessels in submucous membrane. NIR system with LED lights and a CCD camera module was developed to image blood vessels. We measured blood oxygen saturation using the optical density ratio (ODR) of two wavelengths, based on Lambert-Beer law. To image blood vessel clearly and measure blood oxygen saturation accurately, we searched two optimum wavelengths by using a multilayer human gastric-like phantom which has same optical properties as human gastric one. By using Monte Carlo simulation of light propagation, we derived the relationship between the ODR and blood oxygen saturation and elucidated the influence of blood vessel depth on measuring blood oxygen saturation. The oxygen saturation measuring methodology was validated with experiments using our NIR system. Finally, it was confirmed that our system can detect oxygen saturation in various depth blood vessels accurately.

  5. 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...

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

    Science.gov (United States)

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

    1990-01-01

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

  7. Seasonal carbonate chemistry covariation with temperature, oxygen, and salinity in a fjord estuary: implications for the design of ocean acidification experiments.

    Science.gov (United States)

    Reum, Jonathan C P; Alin, Simone R; Feely, Richard A; Newton, Jan; Warner, Mark; McElhany, Paul

    2014-01-01

    Carbonate chemistry variability is often poorly characterized in coastal regions and patterns of covariation with other biologically important variables such as temperature, oxygen concentration, and salinity are rarely evaluated. This absence of information hampers the design and interpretation of ocean acidification experiments that aim to characterize biological responses to future pCO2 levels relative to contemporary conditions. Here, we analyzed a large carbonate chemistry data set from Puget Sound, a fjord estuary on the U.S. west coast, and included measurements from three seasons (winter, summer, and fall). pCO2 exceeded the 2008-2011 mean atmospheric level (392 µatm) at all depths and seasons sampled except for the near-surface waters (Salinity, which varied little (27 to 31), was weakly correlated with carbonate chemistry. We illustrate potential high-frequency changes in carbonate chemistry, temperature, and oxygen conditions experienced simultaneously by organisms in Puget Sound that undergo diel vertical migrations under present-day conditions. We used simple calculations to estimate future pCO2 and Ωar values experienced by diel vertical migrators based on an increase in atmospheric CO2. Given the potential for non-linear interactions between pCO2 and other abiotic variables on physiological and ecological processes, our results provide a basis for identifying control conditions in ocean acidification experiments for this region, but also highlight the wide range of carbonate chemistry conditions organisms may currently experience in this and similar coastal ecosystems.

  8. Effect of low-oxygen-concentration layer on iron gettering capability of carbon-cluster ion-implanted Si wafer for CMOS image sensors

    Science.gov (United States)

    Onaka-Masada, Ayumi; Nakai, Toshiro; Okuyama, Ryosuke; Okuda, Hidehiko; Kadono, Takeshi; Hirose, Ryo; Koga, Yoshihiro; Kurita, Kazunari; Sueoka, Koji

    2018-02-01

    The effect of oxygen (O) concentration on the Fe gettering capability in a carbon-cluster (C3H5) ion-implanted region was investigated by comparing a Czochralski (CZ)-grown silicon substrate and an epitaxial growth layer. A high Fe gettering efficiency in a carbon-cluster ion-implanted epitaxial growth layer, which has a low oxygen region, was observed by deep-level transient spectroscopy (DLTS) and secondary ion mass spectroscopy (SIMS). It was demonstrated that the amount of gettered Fe in the epitaxial growth layer is approximately two times higher than that in the CZ-grown silicon substrate. Furthermore, by measuring the cathodeluminescence, the number of intrinsic point defects induced by carbon-cluster ion implantation was found to differ between the CZ-grown silicon substrate and the epitaxial growth layer. It is suggested that Fe gettering by carbon-cluster ion implantation comes through point defect clusters, and that O in the carbon-cluster ion-implanted region affects the formation of gettering sinks for Fe.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1962-07-01

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

  10. Carbon dioxide assist for non-aqueous sodium–oxygen batteries

    KAUST Repository

    Das, Shyamal K.

    2013-02-01

    We report a novel non-aqueous Na-air battery that utilizes a gas mixture of CO2 and O2. The battery exhibits a high specific energy of 6500-7000 Whkg- 1 (based on the carbon mass) over a range of CO2 feed compositions. The energy density achieved is higher, by 200% to 300%, than that obtained in pure oxygen. Ex-situ FTIR and XRD analysis reveal that Na2O2, Na2C2O 4 and Na2CO3 are the principal discharge products. The Na-CO2/O2 and Mg-CO2/O 2 battery platforms provide a promising, new approach for CO 2 capture and generation of electrical energy. © 2012 Elsevier B.V. All rights reserved.

  11. Isotopic-spectral determination of hydrogen, nitrogen, oxygen and carbon in semiconductor materials

    International Nuclear Information System (INIS)

    Dudich, G.K.; Eremeev, V.A.; Li, V.N.; Nemets, V.M.

    1981-01-01

    Techniques of low-temperature isotopic-spectral determination of impurities of hydrogen, nitrogen, oxygen and carbon in semiconductor materials Bi, Ge, Pb tellurides are developed. The techniques include selection into special vessel with the known volume (exchanger) of sample analyzed, dosed introduction into exchanger of rare isotope of the element determined ( 2 H, 15 N, 18 O, 13 C) in the form of isotope-containing gas, balancing of the determined element isotopes in the system sample-isotope, containing gas, spectroscopic, determination of its isotope composition in gaseous phase of the system and calculation of the amount of the element determined in the sample. The lower boundaries of the amounts determined constitute 10 -7 , 10 -7 , 10 -6 and 10 -5 mass % respectively when sample of 20 g are used [ru

  12. Constraining Phosphorus Chemistry in Carbon- and Oxygen-Rich Circumstellar Envelopes: Observations of PN, HCP, and CP

    Science.gov (United States)

    Milam, S. N.; Halfen, D. T.; Tenenbaum, E. D.; Apponi, A. J.; Woolf, N. J.; Ziurys, L. M.

    2008-09-01

    Millimeter-wave observations of PN, CP, and HCP have been carried out toward circumstellar envelopes of evolved stars using the Arizona Radio Observatory (ARO). HCP and PN have been identified in the carbon-rich source CRL 2688 via observations at 1 mm using the Submillimeter Telescope (SMT) and 2-3 mm with the Kitt Peak 12 m. An identical set of measurements were carried out toward IRC +10216, as well as observations of CP at 1 mm. PN was also observed toward VY Canis Majoris (VY CMa), an oxygen-rich supergiant star. The PN and HCP line profiles in CRL 2688 and IRC +10216 are roughly flat topped, indicating unresolved, optically thin emission; CP, in contrast, has a distinct "U" shape in IRC +10216. Modeling of the line profiles suggests abundances, relative to H2, of f(PN) ~ (3-5) × 10-9 and f(HCP) ~ 2 × 10-7 in CRL 2688, about an order of magnitude higher than in IRC +10216. In VY CMa, f(PN) is ~4 × 10-8. The data in CRL 2688 and IRC +10216 are consistent with LTE formation of HCP and PN in the inner envelope, as predicted by theoretical calculations, with CP a photodissociation product at larger radii. The observed abundance of PN in VY CMa is a factor of 100 higher than LTE predictions. In IRC +10216, the chemistry of HCP/CP mimics that of HCN/CN and suggests an N2 abundance of f ~ 1 × 10-7. The chemistry of phosphorus appears active in both carbon- and oxygen-rich envelopes of evolved stars.

  13. Seasonal Carbonate Chemistry Covariation with Temperature, Oxygen, and Salinity in a Fjord Estuary: Implications for the Design of Ocean Acidification Experiments

    Science.gov (United States)

    Reum, Jonathan C. P.; Alin, Simone R.; Feely, Richard A.; Newton, Jan; Warner, Mark; McElhany, Paul

    2014-01-01

    Carbonate chemistry variability is often poorly characterized in coastal regions and patterns of covariation with other biologically important variables such as temperature, oxygen concentration, and salinity are rarely evaluated. This absence of information hampers the design and interpretation of ocean acidification experiments that aim to characterize biological responses to future pCO2 levels relative to contemporary conditions. Here, we analyzed a large carbonate chemistry data set from Puget Sound, a fjord estuary on the U.S. west coast, and included measurements from three seasons (winter, summer, and fall). pCO2 exceeded the 2008–2011 mean atmospheric level (392 µatm) at all depths and seasons sampled except for the near-surface waters (aragonite were widespread (Ωar<1). We show that pCO2 values were relatively uniform throughout the water column and across regions in winter, enriched in subsurface waters in summer, and in the fall some values exceeded 2500 µatm in near-surface waters. Carbonate chemistry covaried to differing levels with temperature and oxygen depending primarily on season and secondarily on region. Salinity, which varied little (27 to 31), was weakly correlated with carbonate chemistry. We illustrate potential high-frequency changes in carbonate chemistry, temperature, and oxygen conditions experienced simultaneously by organisms in Puget Sound that undergo diel vertical migrations under present-day conditions. We used simple calculations to estimate future pCO2 and Ωar values experienced by diel vertical migrators based on an increase in atmospheric CO2. Given the potential for non-linear interactions between pCO2 and other abiotic variables on physiological and ecological processes, our results provide a basis for identifying control conditions in ocean acidification experiments for this region, but also highlight the wide range of carbonate chemistry conditions organisms may currently experience in this and similar coastal

  14. Combined oxygen- and carbon-isotope records through the Early Jurassic: multiple global events and two modes of carbon-cycle/temperature coupling

    DEFF Research Database (Denmark)

    Hesselbo, Stephen P.; Korte, Christoph

    2010-01-01

    , to the extent that meaningful comparisons between these events can begin to be made. Here we present new carbon and oxygen isotope data from mollusks (bivalves and belemnites) and brachiopods collected through the marine Early Jurassic succession of NE England, including the Sinemurian-Plienbachian boundary...... GSSP. All materials have been screened by chemical analysis and scanning electron microscopy to check for diagenetic alteration. Analysis of carbon isotopes from marine calcite is supplemented by analysis of carbon-isotope values from fossil wood collected through the same section. It is demonstrated...... that both long-term and short-term carbon-isotope shifts from the UK Early Jurassic represent global changes in carbon cycle balances. The Sinemurian-Pliensbachian boundary event is an event of global significance and shows several similarities to the Toarcian OAE (relative sea-level change, carbon-isotope...

  15. Temperature evolution and the oxygen isotope composition of Phanerozoic oceans from carbonate clumped isotope thermometry

    Science.gov (United States)

    Henkes, Gregory A.; Passey, Benjamin H.; Grossman, Ethan L.; Shenton, Brock J.; Yancey, Thomas E.; Pérez-Huerta, Alberto

    2018-05-01

    Surface temperature is among the most important parameters describing planetary climate and habitability, and yet there remains considerable debate about the temperature evolution of the Earth's oceans during the Phanerozoic Eon (541 million years ago to present), the time during which complex metazoan life radiated on Earth. Here we critically assess the emerging record of Phanerozoic ocean temperatures based on carbonate clumped isotope thermometry of fossil brachiopod and mollusk shells, and we present new data that fill important gaps in the Late Paleozoic record. We evaluate and reject the hypothesis that solid-state reordering of 13C-18O bonds has destroyed the primary clumped isotope temperature signal of most fossils during sedimentary burial at elevated temperatures. The resulting Phanerozoic record, which shows a general coupling between tropical seawater temperatures and atmospheric carbon dioxide (CO2) levels since the Paleozoic, indicates that tropical temperatures during the icehouse climate of the Carboniferous period were broadly similar to present (∼25-30 °C), and suggests that benthic metazoans were able to thrive at temperatures of 35-40 °C during intervals of the early and possibly the latest Paleozoic when CO2 levels were likely 5-10× higher than present-day values. Equally important, there is no resolvable trend in seawater oxygen isotope ratios (δ18 O) over the past ∼500 million years, indicating that the average temperature of oxygen exchange between seawater and the oceanic crust has been high (∼270 °C) since at least the early Paleozoic, which points to mid-ocean ridges as the dominant locus of water-rock interaction over the past half-billion years.

  16. The effects of arterial carbon dioxide partial pressure and sevoflurane on capillary venous cerebral blood flow and oxygen saturation during craniotomy.

    Science.gov (United States)

    Klein, Klaus Ulrich; Glaser, Martin; Reisch, Robert; Tresch, Achim; Werner, Christian; Engelhard, Kristin

    2009-07-01

    Intraoperative routine monitoring of cerebral blood flow and oxygenation remains a technological challenge. Using the physiological principle of carbon dioxide reactivity of cerebral vasculature, we investigated a recently developed neuromonitoring device (oxygen-to-see, O2C device) for simultaneous measurements of regional cerebral blood flow (rvCBF), blood flow velocity (rvVelo), oxygen saturation (srvO2), and hemoglobin amount (rvHb) at the capillary venous level in patients subjected to craniotomy. Twenty-six neurosurgical patients were randomly assigned to anesthesia with 1.4% or 2.0% sevoflurane end-tidal concentration. After craniotomy, a fiberoptic probe was applied on a macroscopically healthy surface of cerebral tissue next to the site of surgery. Simultaneous measurements in 2 and 8 mm cerebral depth were performed in each patient during lower (35 mm Hg) and higher (45 mm Hg) levels (random order) of arterial carbon dioxide partial pressure (PaCO2). The principle of these measurements relies on the combination of laser-Doppler flowmetry (rvCBF, rvVelo) and photo-spectrometry (srvO2, rvHb). Linear models were fitted to test changes of end points (rvCBF, rvVelo, srvO2, rvHb) in response to lower and higher levels of PaCO2, 1.4% and 2.0% sevoflurane end-tidal concentration, and 2 and 8 mm cerebral depth. RvCBF and rvVelo were elevated by PaCO2 independent of sevoflurane concentration in 2 and 8 mm depth of cerebral tissue (P oxygen was decreased by elevated PaCO2. Unchanged levels of rvHb signify that there was no blood loss during measurements. Data suggest that the device allows detection of local changes in blood flow and oxygen saturation in response to different PaCO2 levels in predominant venous cerebral microvessels.

  17. Thermodynamics of the hydrogen-carbon-oxygen-tungsten system, as applied to the manufacture of tungsten and tungsten carbide

    International Nuclear Information System (INIS)

    Schwenke, G.K.

    2001-01-01

    The thermodynamics of the quaternary hydrogen-carbon oxygen-tungsten system and its binary and ternary sub-systems are reviewed. Published thermodynamic data are evaluated, and expression for free energies of formation are chosen. These expressions are integrated with and equilibrium-calculating algorithm, producing a powerful tool for understanding and improving the manufacture of tungsten and tungsten carbide. Three examples are presented: reduction/carburization of tungstic oxide with hydrogen, carbon, and methane. (author)

  18. Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

    KAUST Repository

    Alquaity, Awad; Han, Jie; Chahine, May; Selim, Hatem; Belhi, Memdouh; Sarathy, Mani; Bisetti, Fabrizio; Farooq, Aamir

    2016-01-01

    chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon

  19. Supplementary Material for: Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

    KAUST Repository

    Alquaity, Awad B. S.; Han, Jie; Chahine, May; Selim, Hatem; Belhi, Memdouh; Sarathy, Mani; Bisetti, Fabrizio; Farooq, Aamir

    2017-01-01

    chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon

  20. Supernova SN 2011fe from an exploding carbon-oxygen white dwarf star.

    Science.gov (United States)

    Nugent, Peter E; Sullivan, Mark; Cenko, S Bradley; Thomas, Rollin C; Kasen, Daniel; Howell, D Andrew; Bersier, David; Bloom, Joshua S; Kulkarni, S R; Kandrashoff, Michael T; Filippenko, Alexei V; Silverman, Jeffrey M; Marcy, Geoffrey W; Howard, Andrew W; Isaacson, Howard T; Maguire, Kate; Suzuki, Nao; Tarlton, James E; Pan, Yen-Chen; Bildsten, Lars; Fulton, Benjamin J; Parrent, Jerod T; Sand, David; Podsiadlowski, Philipp; Bianco, Federica B; Dilday, Benjamin; Graham, Melissa L; Lyman, Joe; James, Phil; Kasliwal, Mansi M; Law, Nicholas M; Quimby, Robert M; Hook, Isobel M; Walker, Emma S; Mazzali, Paolo; Pian, Elena; Ofek, Eran O; Gal-Yam, Avishay; Poznanski, Dovi

    2011-12-14

    Type Ia supernovae have been used empirically as 'standard candles' to demonstrate the acceleration of the expansion of the Universe even though fundamental details, such as the nature of their progenitor systems and how the stars explode, remain a mystery. There is consensus that a white dwarf star explodes after accreting matter in a binary system, but the secondary body could be anything from a main-sequence star to a red giant, or even another white dwarf. This uncertainty stems from the fact that no recent type Ia supernova has been discovered close enough to Earth to detect the stars before explosion. Here we report early observations of supernova SN 2011fe in the galaxy M101 at a distance from Earth of 6.4 megaparsecs. We find that the exploding star was probably a carbon-oxygen white dwarf, and from the lack of an early shock we conclude that the companion was probably a main-sequence star. Early spectroscopy shows high-velocity oxygen that slows rapidly, on a timescale of hours, and extensive mixing of newly synthesized intermediate-mass elements in the outermost layers of the supernova. A companion paper uses pre-explosion images to rule out luminous red giants and most helium stars as companions to the progenitor.

  1. Oxygen and carbon transfer during solidification of semiconductor grade silicon in different processes

    Science.gov (United States)

    Ribeyron, P. J.; Durand, F.

    2000-03-01

    A model is established for comparing the solute distribution resulting from four solidification processes currently applied to semiconductor grade silicon: Czochralski pulling (CZ), floating zone (FZ), 1D solidification and electromagnetic continuous pulling (EMCP). This model takes into account solid-liquid interface exchange, evaporation to or contamination by the gas phase, container dissolution, during steady-state solidification, and in the preliminary preparation of the melt. For simplicity, the transfers are treated in the crude approximation of perfectly mixed liquid and boundary layers. As a consequence, only the axial ( z) distribution can be represented. Published data on oxygen and carbon transfer give a set of acceptable values for the thickness of the boundary layers. In the FZ and EMCP processes, oxygen evaporation can change the asymptotic behaviour of the reference Pfann law. In CZ and in 1D-solidification, a large variety of solute profile curves can be obtained, because they are very sensitive to the balance between crucible dissolution and evaporation. The CZ process clearly brings supplementary degrees of freedom via the geometry of the crucible, important for the dissolution phenomena, and via the rotation rate of the crystal and of the crucible, important for acting on transfer kinetics.

  2. Carbon-supported cubic CoSe2 catalysts for oxygen reduction reaction in alkaline medium

    International Nuclear Information System (INIS)

    Feng Yongjun; Alonso-Vante, Nicolas

    2012-01-01

    Highlights: ► Cubic CoSe 2 a non-precious metal electrocatalyst for oxygen reduction in KOH. ► The catalyst shows four-electron transfer pathway in overall reaction. ► Catalyst has higher methanol tolerance than commercial Pt/C catalyst. - Abstract: A Carbon-supported CoSe 2 nanocatalyst has been developed as an alternative non-precious metal electrocatalyst for oxygen reduction reaction (ORR) in alkaline medium. The catalyst was prepared via a surfactant-free route and its electrocatalytic activity for the ORR has been investigated in detail in 0.1 M KOH electrolyte at 25 °C using rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) techniques. The prepared catalyst showed promising catalytic activity towards ORR in a four-electron transfer pathway and higher tolerance to methanol compared to commercial Pt/C catalyst in 0.1 M KOH. To some extent, the increase of CoSe 2 loading on the electrode favors a faster reduction of H 2 O 2 intermediate to H 2 O.

  3. Oxygen reduction at platinum nanoparticles supported on carbon cryogel in alkaline solution

    Directory of Open Access Journals (Sweden)

    N. R. ELEZOVIC

    2007-07-01

    Full Text Available The oxygen reduction reaction was investigated in 0.1 M NaOH solution, on a porous coated electrode formed of Pt particles supported on carbon cryogel. The Pt/C catalyst was characterized by the X-ray diffraction (XRD, transmission electron microscopy (TEM and cyclic voltammetry techniques. The results demonstrated a successful reduction of Pt to metallic form and homogenous Pt particle size distribution with a mean particle size of about 2.7 nm. The ORR kinetics was investigated by linear sweep polarization at a rotating disc electrode. The results showed the existence of two E – log j regions, usually referred to polycrystalline Pt in acid and alkaline solution. At low current densities (lcd, the Tafel slope was found to be close to –2.3RT/F, while at high current densities (hcd it was found to be close to –2×2.3RT/F. It is proposed that the main path in the ORR mechanism on Pt particles was the direct four-electron process, with the transfer of the first electron as the rate determining step. If the activities are expressed through the specific current densities, a small enhancement of the catalytic activity for Pt/C was observed compared to that of polycrystalline Pt. The effect of the Pt particle size on the electrocatalysis of oxygen reduction was ascribed to the predominant (111 facets of the platinum crystallites.

  4. Extreme diel dissolved oxygen and carbon cycles in shallow vegetated lakes.

    Science.gov (United States)

    Andersen, Mikkel R; Kragh, Theis; Sand-Jensen, Kaj

    2017-09-13

    A common perception in limnology is that shallow lakes are homogeneously mixed owing to their small water volume. However, this perception is largely gained by downscaling knowledge from large lakes to their smaller counterparts. Here we show that shallow vegetated lakes (less than 0.6 m), in fact, undergo recurring daytime stratification and nocturnal mixing accompanied by extreme chemical variations during summer. Dense submerged vegetation effectively attenuates light and turbulence generating separation between warm surface waters and much colder bottom waters. Photosynthesis in surface waters produces oxygen accumulation and CO 2 depletion, whereas respiration in dark bottom waters causes anoxia and CO 2 accumulation. High daytime pH in surface waters promotes precipitation of CaCO 3 which is re-dissolved in bottom waters. Nocturnal convective mixing re-introduces oxygen into bottom waters for aerobic respiration and regenerated inorganic carbon into surface waters, which supports intense photosynthesis. Our results reconfigure the basic understanding of local environmental gradients in shallow lakes, one of the most abundant freshwater habitats globally. © 2017 The Author(s).

  5. Stratigraphy on Oxygen and Carbon Isotope of Paciran Formation East Java

    International Nuclear Information System (INIS)

    Premonowati; R P Koesoemadinata; Harsono-Pringgoprawiro; Wahyoe-S-Hantoro

    2004-01-01

    Paleotemperature fluctuation in tropical zone (centennial and decad al scale) has been known. It's based on stable isotopic analysis from each of unconformity zones. Those boundaries have derived on reef units of shallows marine reef complex of Paciran Formation, Tuban area in Northeast Java Basin. From 25 samples have been choosen on undeformed calcite and analyzed by oxygen and carbon stable isotope. It used to validizing a sea level changes during the formation to Reef 1 to Reef 17 from Paciran formation with sea surface temperature (SST) since 4 Ma until now. On early forming of Reef 1 to Reef 3 (since 4 Ma - 2,88 Ma), sea level occurred marine flooding surface. Since the formation of reef 4 (2,59 Ma) to Reef 8 (1,4 Ma) occurred stagnant temperature and almost to warmer condition. Then, δ 18 O have arise up drastically to 5 0/00 and shows warmer condition to Reef 8 formation, in contrary, the sea level have been arised to Reef 10 formation (0,7 Ma). The temperature have been fluctuated between 0,5 o and 1 o C until the formation of Reef 17 (Early Holocene) and continued to Reef 17 formation at 2 o C based on the rapidity sampling of Po rites sp. Wholly, in centennial scale, since the formation of Reef 4 (2,59 Ma) to Reef 17 (1 Ma), the curve of oxygen stable isotope shows decrease or cooler condition. Those condition have conducted to sea level drop since the formation to Reef 7 and Reef 8. There are 4 periods of interglacial since the formation of Reef 4. The warmer condition indicated since the formation of Reef 9, Reef 11 and Reef 17. Recently, a curve of oxygen isotopes reveals warmer drastically or sea level have been arisen. (author)

  6. A new method to measure and model dynamic oxygen microdistributions in moving biofilms.

    Science.gov (United States)

    Wang, Jian-Hui; Chen, You-Peng; Dong, Yang; Wang, Xi-Xi; Guo, Jin-Song; Shen, Yu; Yan, Peng; Ma, Teng-Fei; Sun, Xiu-Qian; Fang, Fang; Wang, Jing

    2017-10-01

    Biofilms in natural environments offer a superior solution to mitigate water pollution. Artificially intensified biofilm reactors represented by rotating biological contactors (RBCs) are widely applied and studied. Understanding the oxygen transfer process in biofilms is an important aspect of these studies, and describing this process in moving biofilms (such as biofilms in RBCs) is a particular challenge. Oxygen transfer in RBCs behaves differently than in other biological reactors due to the special oxygen supply mode that results from alternate exposure of the biofilm to wastewater and air. The study of oxygen transfer in biofilms is indispensable for understanding biodegradation in RBCs. However, the mechanisms are still not well known due to a lack of effective tools to dynamically analyze oxygen diffusion, reaction, and microdistribution in biofilms. A new experimental device, the Oxygen Transfer Modeling Device (OTMD), was designed and manufactured for this purpose, and a mathematical model was developed to model oxygen transfer in biofilm produced by an RBC. This device allowed the simulation of the local environment around the biofilm during normal RBC operation, and oxygen concentrations varying with time and depth in biofilm were measured using an oxygen microelectrode. The experimental data conformed well to the model description, indicating that the OTMD and the model were stable and reliable. Moreover, the OTMD offered a flexible approach to study the impact of a single-factor on oxygen transfer in moving biofilms. In situ environment of biofilm in an RBC was simulated, and dynamic oxygen microdistributions in the biofilm were measured and well fitted to the built model description. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Influence of oxygen, nitrogen and carbon on the lattice parameter of uranium mono-carbide; Influence de l'oxygene, de l'azote et du carbone sur le parametre reticulaire du monocarbure d'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Magnier, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-04-15

    The author studies the influence of oxygen and nitrogen contents on the lattice parameter of U(C,O,N) solid solutions around UC composition. The whole data conducts to a determination of the solubility of oxygen in UC: a U(C(1-x)O(x)) solid solution exist if x if smaller than 0.37. The author studies also the influence of carbon content on the lattice parameter of U-UC solid solutions around UC. This study conducts to the determination of the solubility of U in UC at the different temperatures. Consequences upon uranium-carbon diagram are envisaged. (author) [French] L'auteur etudie quantitativement l'influence de l'oxygene et de l'azote sur le parametre reticulaire des solutions solides U(C,O,N) proches de UC. Cette etude permet la determination de la solubilite de l'oxygene dans UC: on montre l'existence d'une solution solide U(C(1-x)O(x)) lorsque x est compris entre 0 et 0,37. Par ailleurs l'auteur etudie l'influence de la teneur en carbone sur le parametre des solutions solides U-UC proches de UC. Cette etude permet la determination de la solubilite de l'uranium dans UC aux differentes temperatures. On envisage enfin les modifications apportees par cette etude au diagramme uranium-carbone. (auteur)

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

    Science.gov (United States)

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

    2013-09-01

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

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

    International Nuclear Information System (INIS)

    Sasai, K.; Brown, J.M.

    1994-01-01

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

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

    DEFF Research Database (Denmark)

    Chipman, Lindsay; Huettel, Markus; Berg, Peter

    2012-01-01

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

  11. Drought sensitivity of Amazonian carbon balance revealed by atmospheric measurements

    Science.gov (United States)

    Gatti, L. V.; Gloor, M.; Miller, J. B.; Doughty, C. E.; Malhi, Y.; Domingues, L. G.; Basso, L. S.; Martinewski, A.; Correia, C. S. C.; Borges, V. F.; Freitas, S.; Braz, R.; Anderson, L. O.; Rocha, H.; Grace, J.; Phillips, O. L.; Lloyd, J.

    2014-02-01

    Feedbacks between land carbon pools and climate provide one of the largest sources of uncertainty in our predictions of global climate. Estimates of the sensitivity of the terrestrial carbon budget to climate anomalies in the tropics and the identification of the mechanisms responsible for feedback effects remain uncertain. The Amazon basin stores a vast amount of carbon, and has experienced increasingly higher temperatures and more frequent floods and droughts over the past two decades. Here we report seasonal and annual carbon balances across the Amazon basin, based on carbon dioxide and carbon monoxide measurements for the anomalously dry and wet years 2010 and 2011, respectively. We find that the Amazon basin lost 0.48+/-0.18 petagrams of carbon per year (PgCyr-1) during the dry year but was carbon neutral (0.06+/-0.1PgCyr-1) during the wet year. Taking into account carbon losses from fire by using carbon monoxide measurements, we derived the basin net biome exchange (that is, the carbon flux between the non-burned forest and the atmosphere) revealing that during the dry year, vegetation was carbon neutral. During the wet year, vegetation was a net carbon sink of 0.25+/-0.14PgCyr-1, which is roughly consistent with the mean long-term intact-forest biomass sink of 0.39+/-0.10PgCyr-1 previously estimated from forest censuses. Observations from Amazonian forest plots suggest the suppression of photosynthesis during drought as the primary cause for the 2010 sink neutralization. Overall, our results suggest that moisture has an important role in determining the Amazonian carbon balance. If the recent trend of increasing precipitation extremes persists, the Amazon may become an increasing carbon source as a result of both emissions from fires and the suppression of net biome exchange by drought.

  12. Validation of a novel device to objectively measure adherence to long-term oxygen therapy

    Directory of Open Access Journals (Sweden)

    Sun-Kai V Lin

    2008-10-01

    Full Text Available Sun-Kai V Lin1, Daniel K Bogen1, Samuel T Kuna2,31Department of Bioengineering; 2Department of Medicine, Pulmonary, Allergy and Critical Care Division, and Center for Sleep and Respiratory Neurobiology, University of Pennsylvania, Pennsylvania, USA; 3Department of Medicine, Philadelphia Veterans Affairs Medical Center Philadelphia, Pennsylvania, USARationale: We have developed a novel oxygen adherence monitor that objectively measures patient use of long-term oxygen therapy. The monitor attaches to the oxygen source and detects whether or not the patient is wearing the nasal cannula.Objective: The study’s purpose was to validate the monitor’s performance in patients with chronic obstructive pulmonary disease during wakefulness and sleep.Methods: Ten adult males with stable chronic obstructive pulmonary disease (mean ± SD FEV1 37.7 ± 14.9% of predicted on long-term continuous oxygen therapy were tested in a sleep laboratory over a 12–13 hour period that included an overnight polysomnogram.Measurements: The monitor’s measurements were obtained at 4-minute intervals and compared to actual oxygen use determined by review of time-synchronized video recordings.Main results: The monitor made 1504/1888 (79.7% correct detections (unprocessed data across all participants: 957/1,118 (85.6% correct detections during wakefulness and 546/770 (70.9% during sleep. All errors were false negatives, ie, the monitor failed to detect that the participant was actually wearing the cannula. Application of a majority-vote filter to the raw data improved overall detection accuracy to 84.9%.Conclusions: The results demonstrate the monitor’s ability to objectively measure whether or not men with chronic obstructive pulmonary disease are receiving their oxygen treatment. The ability to objectively measure oxygen delivery, rather than oxygen expended, may help improve the management of patients on long-term oxygen therapy.Keywords: chronic obstructive pulmonary

  13. [Measurement model of carbon emission from forest fire: a review].

    Science.gov (United States)

    Hu, Hai-Qing; Wei, Shu-Jing; Jin, Sen; Sun, Long

    2012-05-01

    Forest fire is the main disturbance factor for forest ecosystem, and an important pathway of the decrease of vegetation- and soil carbon storage. Large amount of carbonaceous gases in forest fire can release into atmosphere, giving remarkable impacts on the atmospheric carbon balance and global climate change. To scientifically and effectively measure the carbonaceous gases emission from forest fire is of importance in understanding the significance of forest fire in the carbon balance and climate change. This paper reviewed the research progress in the measurement model of carbon emission from forest fire, which covered three critical issues, i. e., measurement methods of forest fire-induced total carbon emission and carbonaceous gases emission, affecting factors and measurement parameters of measurement model, and cause analysis of the uncertainty in the measurement of the carbon emissions. Three path selections to improve the quantitative measurement of the carbon emissions were proposed, i. e., using high resolution remote sensing data and improving algorithm and estimation accuracy of burned area in combining with effective fuel measurement model to improve the accuracy of the estimated fuel load, using high resolution remote sensing images combined with indoor controlled environment experiments, field measurements, and field ground surveys to determine the combustion efficiency, and combining indoor controlled environment experiments with field air sampling to determine the emission factors and emission ratio.

  14. Oxygen reduction reaction on carbon-supported CoSe2 nanoparticles in an acidic medium

    International Nuclear Information System (INIS)

    Feng Yongjun; He Ting; Alonso-Vante, Nicolas

    2009-01-01

    We investigated the effect of CoSe 2 /C nanoparticle loading rate on oxygen reduction reaction (ORR) activity and H 2 O 2 production using the rotating disk electrode and the rotating ring-disk electrode techniques. We prepared carbon-supported CoSe 2 nanoparticles with different nominal loading rates and evaluated these samples by means of powder X-ray diffraction. All the catalysts had an OCP value of 0.81 V vs. RHE. H 2 O 2 production during the ORR process decreased with an increase in catalytic layer thickness. This decrease was related to the CoSe 2 loading on the disk electrode. H 2 O 2 production also decreased with increasing catalytic site density, a phenomenon related to the CoSe 2 loading rate on the carbon substrate. The cathodic current density significantly increased with increasing catalytic layer thickness, but decreased with increasing catalytic site density. In the case of 20 wt% CoSe 2 /C nanoparticles at 22 μg cm -2 , we determined that the transfer process involves about 3.5 electrons.

  15. A Pt-free Electrocatalyst Based on Pyrolized Vinazene-Carbon Composite for Oxygen Reduction Reaction

    International Nuclear Information System (INIS)

    Akinpelu, Akeem; Merzougui, Belabbes; Bukola, Saheed; Azad, Abdul-Majeed; Basheer, Rafil A.; Swain, Greg M.; Chang, Qiaowan; Shao, Minhua

    2015-01-01

    The 2-vinyl-4, 5-dicyanoimidazole (Vinazene) was used as a nitrogen precursor to synthesize a promising non-precious metal (NPM) catalyst for oxygen reduction reaction (ORR). Vinazene together with an iron source was impregnated into a carbon matrix and pyrolyzed at 900 °C in N 2 atmosphere. The structure of the resulting Fe–N–C nanocomposite was analyzed by X-ray photoelectron spectroscopy, Raman spectroscopy and X-ray diffraction. Both rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) experiments showed excellent ORR activity for the obtained catalyst with low H 2 O 2 formation (∼3.0%) in 0.1 M KOH. The catalyst was found to be rich in mesoporous structure along with high percentage of pyrrolic-N function with surface area of about 673 m 2 g −1 and pore size of 4.2 nm. In addition to its excellent ORR activity, the catalyst showed remarkable tolerance towards methanol oxidation and demonstrates good stability over 10,000 potential cycles (0.6–1.0 V Vs RHE). We believe that this N-rich Vinazene molecule will be beneficial to further development of nitrogen doped carbon electrocatalysts

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

    Science.gov (United States)

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

    2018-03-01

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

  17. Measurement of carbon activity of sodium using nickel tabs and the Harwell Carbon Meter - Preliminary experience

    International Nuclear Information System (INIS)

    Blundell, A.; Thorley, A.W.

    1980-01-01

    Carbon can have an important effect on the mechanical properties of certain constructional materials likely to be used in the LMFBRs. Transfer of carbon will occur between the metal and the sodium at any particular location to bring the chemical potential of carbon in both components to the sam: value. Thus, in a mixed system containing austenitic stainless steel and unstabilized ferritic steel, carbon could be transferred by the sodium from the high carbon activity ferritic to the lower activity austenitic steel. Loss of carbon from the unstabilized ferritic steel leads to a weaker, more ductile material, while carburization of the stainless steel could lead to its embrittlement. Similarly carbon entering the coolant in the form of oil from leaking mechanical pumps could have similar effects on the mechanical property of stainless steels. In the light of these possibilities it is essential to measure the carbon activity of the sodium so that its effect on materials properties can be predicted

  18. Measurement of carbon activity of sodium using nickel tabs and the Harwell Carbon Meter - Preliminary experience

    Energy Technology Data Exchange (ETDEWEB)

    Blundell, A; Thorley, A W [UKAEA, Risley, Warrington, Cheshire (United Kingdom)

    1980-05-01

    Carbon can have an important effect on the mechanical properties of certain constructional materials likely to be used in the LMFBRs. Transfer of carbon will occur between the metal and the sodium at any particular location to bring the chemical potential of carbon in both components to the sam: value. Thus, in a mixed system containing austenitic stainless steel and unstabilized ferritic steel, carbon could be transferred by the sodium from the high carbon activity ferritic to the lower activity austenitic steel. Loss of carbon from the unstabilized ferritic steel leads to a weaker, more ductile material, while carburization of the stainless steel could lead to its embrittlement. Similarly carbon entering the coolant in the form of oil from leaking mechanical pumps could have similar effects on the mechanical property of stainless steels. In the light of these possibilities it is essential to measure the carbon activity of the sodium so that its effect on materials properties can be predicted.

  19. LUMOS - A Sensitive and Reliable Optode System for Measuring Dissolved Oxygen in the Nanomolar Range

    DEFF Research Database (Denmark)

    Lehner, Philipp; Larndorfer, Christoph; Garcia-Robledo, Emilio

    2015-01-01

    Most commercially available optical oxygen sensors target the measuring range of 300 to 2 mu mol L-1. However these are not suitable for investigating the nanomolar range which is relevant for many important environmental situations. We therefore developed a miniaturized phase fluorimeter based...... for read out of less sensitive optical oxygen sensors based on the same or similar indicator dyes, for example for monitoring oxygen at physiological conditions. The presented sensor system exhibits lower noise, higher resolution and higher sensitivity than the electrochemical STOX sensor previously used...... measurement system called the LUMOS (Luminescence Measuring Oxygen Sensor). It consists of a readout device and specialized "sensing chemistry" that relies on commercially available components. The sensor material is based on palladium(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin embedded...

  20. Oceanic acidification affects marine carbon pump and triggers extended marine oxygen holes.

    Science.gov (United States)

    Hofmann, Matthias; Schellnhuber, Hans-Joachim

    2009-03-03

    Rising atmospheric CO(2) levels will not only drive future global mean temperatures toward values unprecedented during the whole Quaternary but will also lead to massive acidification of sea water. This constitutes by itself an anthropogenic planetary-scale perturbation that could significantly modify oceanic biogeochemical fluxes and severely damage marine biota. As a step toward the quantification of such potential impacts, we present here a simulation-model-based assessment of the respective consequences of a business-as-usual fossil-fuel-burning scenario where a total of 4,075 Petagrams of carbon is released into the atmosphere during the current millennium. In our scenario, the atmospheric pCO(2) level peaks at approximately 1,750 microatm in the year 2200 while the sea-surface pH value drops by >0.7 units on global average, inhibiting the growth of marine calcifying organisms. The study focuses on quantifying 3 major concomitant effects. The first one is a significant (climate-stabilizing) negative feedback on rising pCO(2) levels as caused by the attenuation of biogenic calcification. The second one is related to the biological carbon pump. Because mineral ballast, notably CaCO(3), is found to play a dominant role in carrying organic matter through the water column, a reduction of its export fluxes weakens the strength of the biological carbon pump. There is, however, a third effect with severe consequences: Because organic matter is oxidized in shallow waters when mineral-ballast fluxes weaken, oxygen holes (hypoxic zones) start to expand considerably in the oceans in our model world--with potentially harmful impacts on a variety of marine ecosystems.

  1. UV-Vis, infrared, and mass spectroscopy of electron irradiated frozen oxygen and carbon dioxide mixtures with water

    International Nuclear Information System (INIS)

    Jones, Brant M.; Kaiser, Ralf I.; Strazzulla, Giovanni

    2014-01-01

    Ozone has been detected on the surface of Ganymede via observation of the Hartley band through the use of ultraviolet spectroscopy and is largely agreed upon to be formed by radiolytic processing via interaction of magnetospheric energetic ions and/or electrons with oxygen-bearing ices on Ganymede's surface. Interestingly, a clearly distinct band near 300 nm within the shoulder of the UV-Vis spectrum of Ganymede was also observed, but currently lacks an acceptable physical or chemical explanation. Consequently, the primary motivation behind this work was the collection of UV-Vis absorption spectroscopy of ozone formation by energetic electron bombardment of a variety of oxygen-bearing ices (oxygen, carbon dioxide, water) relevant to this moon as well as other solar system. Ozone was indeed synthesized in pure ices of molecular oxygen, carbon dioxide and a mixture of water and oxygen, in agreement with previous studies. The Hartley band of the ozone synthesized in these ice mixtures was observed in the UV-Vis spectra and compared with the spectrum of Ganymede. In addition, a solid state ozone absorption cross section of 6.0 ± 0.6 × 10 –17 cm 2 molecule –1 was obtained from the UV-Vis spectral data. Ozone was not produced in the irradiated carbon dioxide-water mixtures; however, a spectrally 'red' UV continuum is observed and appears to reproduce well what is observed in a large number of icy moons such as Europa.

  2. Unlocking the Electrocatalytic Activity of Chemically Inert Amorphous Carbon-Nitrogen for Oxygen Reduction: Discerning and Refactoring Chaotic Bonds

    DEFF Research Database (Denmark)

    Zhang, Caihong; Zhang, Wei; Wang, Dong

    2017-01-01

    Mild annealing enables inactive nitrogen (N)-doped amorphous carbon (a-C) films abundant with chaotic bonds prepared by magnetron sputtering to become effective for the oxygen reduction reaction (ORR) by virtue of generating pyridinic N. The rhythmic variation of ORR activity elaborates well...... on the subtle evolution of the amorphous C−N bonds conferred by spectroscopic analysis....

  3. Regional myocardial oxygen consumption estimated by carbon-11 acetate and positron emission tomography before and after repetitive ischemia

    DEFF Research Database (Denmark)

    Kofoed, K F; Hansen, P R; Holm, S

    2011-01-01

    Preserved myocardial oxygen consumption estimated by carbon 11-acetate and positron emission tomography (PET) in myocardial regions with chronic but reversibly depressed contractile function in patients with ischemic heart disease have been suggested to be caused by repeated short episodes of acu...

  4. Study on carbon-fixing,oxygen-releasing,temperature-reducing and humidity-increasing effects of evergreen plants in south highway

    Directory of Open Access Journals (Sweden)

    LIU Minmin

    2014-04-01

    Full Text Available Li-6400 portable photosynthesis system,was used to test the diurnal variations of photosynthetic rate and stomatal conductance of evergreen plants in Southern Highway,and to calculate their ability of absorbing carbon dioxide and releasing oxygen and to calculate the transpiring water volume and absorbing heat quantity of plants.Results showed that Euonymus fortunei Hand-Mazz,Hedera helix.Aucuba eriobotryaefolia had better carbon-fixing and oxygen-releasing effects,while Photinia serrulata,Trachycarpus fortunei,Radix Ophiopogonis had worse carbon-fixing and oxygen-releasing effects.Radix Ophiopogonis,Photinia glabra,Euonymus fortunei Hand.-Mazz had higher cooling and humidification ability,while Photinia serrulata,Trachycarpus fortunei did not act as well as them.Euonymus fortunei Hand.-Mazz and Hedera helix had higher leaf chlorophyll in per unit mass,values are 12.91、10.34、9.93 mg·g-1.Radix Ophiopogonis、Cinnamomum camphora(Linn. Presl and Trachycarpus fortunei had lower leaf chlorophyll in per unit mass,value is 3.55、2.67、2.06 mg·g-1.Releasing oxygen,fixing carbon,net assimilation and chlorophyll content has good correlation(P<0.05.

  5. Determination of oxygen content and carbonate impurity in YBa2Cu3O7-x by diffuse reflectance infrared spectroscopy

    International Nuclear Information System (INIS)

    Merzbacher, C.I.; Bonner, B.P.

    1991-01-01

    Samples of YBa 2 Cu 3 O 7-x with x ranging from ∼0 to 0.65 have been analyzed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) in the midinfrared region (400--6000 cm -1 ). Spectral line shapes vary gradually as a function of oxygen stoichiometry, and the reflectance at 400 and 1000 cm -1 decreases linearly with decreasing oxygen content. Spectra of samples that were incompletely synthesized or exposed to a 4% CO 2 atmosphere at 650 degree C clearly indicated the presence of carbonate. DRIFTS is therefore a quick, nondestructive method for determining oxygen content in YBa 2 Cu 3 O 7-x powders, and for detecting carbonate species due to synthesis error or reaction with CO 2 -bearing atmosphere

  6. Experimental reduction of simulated lunar glass by carbon and hydrogen and implications for lunar base oxygen production

    International Nuclear Information System (INIS)

    Mckay, D.S.; Morris, R.V.; Jurewicz, A.J.

    1991-01-01

    The most abundant element in lunar rocks and soils is oxygen which makes up approximately 45 percent by weight of the typical lunar samples returned during the Apollo missions. This oxygen is not present as a gas but is tightly bound to other elements in mineral or glass. When people return to the Moon to explore and live, the extraction of this oxygen at a lunar outpost may be a major goal during the early years of operation. Among the most studied processes for oxygen extraction is the reduction of ilmenite by hydrogen gas to form metallic iron, titanium oxide, and oxygen. A related process is proposed which overcomes some of the disadvantages of ilmenite reduction. It is proposed that oxygen can be extracted by direct reduction of native lunar pyroclactic glass using either carbon, carbon monoxide, or hydrogen. In order to evaluate the feasibility of this proposed process a series of experiments on synthetic lunar glass are presented. The results and a discussion of the experiments are presented

  7. Effect of oxygen co-injected with carbon dioxide on Gothic shale caprock–CO2–brine interaction during geologic carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hun Bok; Um, Wooyong; Cantrell, Kirk J.

    2013-09-01

    Co-injection of oxygen, a significant component in CO2 streams produced by the oxyfuel combustion process, can cause a significant alteration of the redox state in deep geologic formations during geologic carbon sequestration. The potential impact of co-injected oxygen on the interaction between synthetic CO2–brine (0.1 M NaCl) and shale caprock (Gothic shale from the Aneth Unit in Utah) and mobilization of trace metals was investigated at ~ 10 MPa and ~ 75 °C. A range of relative volume percentages of O2 to CO2 (0, 1, 4 and 8%) were used in these experiments to address the effect of oxygen on shale–CO2–brine interaction under various conditions. Major mineral phases in Gothic shale are quartz, calcite, dolomite, montmorillonite, and pyrite. During Gothic shale–CO2–brine interaction in the presence of oxygen, pyrite oxidation occurred extensively and caused enhanced dissolution of calcite and dolomite. Pyrite oxidation and calcite dissolution subsequently resulted in the precipitation of Fe(III) oxides and gypsum (CaSO4·2H2O). In the presence of oxygen, dissolved Mn and Ni were elevated because of oxidative dissolution of pyrite. The mobility of dissolved Ba was controlled by barite (BaSO4) precipitation in the presence of oxygen. Dissolved U in the experimental brines increased to ~ 8–14 μg/L, with concentrations being slightly higher in the absence of oxygen than in the presence of oxygen. Experimental and modeling results indicate the interaction between shale caprock and oxygen co-injected with CO2 during geologic carbon sequestration can exert significant impacts on brine pH, solubility of carbonate minerals, stability of sulfide minerals, and mobility of trace metals. The major impact of oxygen is most likely to occur in the zone near CO2 injection wells where impurity gases can accumulate. Finally, oxygen in CO2

  8. Influence of Micropore and Mesoporous in Activated Carbon Air-cathode Catalysts on Oxygen Reduction Reaction in Microbial Fuel Cells

    International Nuclear Information System (INIS)

    Liu, Yi; Li, Kexun; Ge, Baochao; Pu, Liangtao; Liu, Ziqi

    2016-01-01

    In this study, carbon samples with different micropore and mesoporous structures are prepared as air-cathode catalyst layer to explore the role of pore structure on oxygen reduction reaction. The results of linear sweep voltammetry and power density show that the commercially-produced activated carbon (CAC) has the best electrochemical performance, and carbon samples with only micropore or mesoporous show lower performance than CAC. Nitrogen adsorption-desorption isotherms analysis confirm that CAC has highest surface area (1616 m 2 g −1 ) and a certain amount of micropore and mesoporous. According to Tafel plot and rotating disk electrode, CAC behaves the highest kinetic activity and electron transfer number, leading to the improvement of oxygen reduction reaction. The air permeability test proves that mesoporous structure enhance oxygen permeation. Carbon materials are also analyzed by In situ Fourier Transform Infrared Spectroscopy and H 2 temperature programmed reduction, which indicate that micropore provide active sites for catalysis. In a word, micropore and mesoporous together would improve the electrochemical performance of carbon materials.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-30

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

  11. Noninvasive determination of myocardial blood flow, oxygen consumption and efficiency in normal humans by carbon-11 acetate positron emission tomography imaging

    International Nuclear Information System (INIS)

    Porenta, G.; Cherry, S.; Czernin, J.; Brunken, R.; Kuhle, W.; Hashimoto, T.; Schelbert, H.R.

    1999-01-01

    The aims of this study were: (1) to measure noninvasively and near simultaneously myocardial blood flow, oxygen consumption, and contractile function and (2) to analyze myocardial energy expenditure and efficiency at rest and during dobutamine stress in normal humans. Dynamic and gated carbon-11 acetate positron emission tomography (PET) imaging was performed in 11 normal subjects. The initial uptake of 11 C-acetate was measured to estimate myocardial blood flow. Oxygen consumption was derived from the monoexponential slope of the 11 C-clearance curve recorded during myocardial washout. ECG-gated systolic and diastolic images were acquired during the peak myocardial 11 C activity to measure left ventricular radius, myocardial wall thickness, and long axis length. Myocardial oxygen consumption and parameters of cardiac geometry were used to determine myocardial energetics and cardiac efficiency by tension-area area analysis. Myocardial blood flow averaged 0.8±0.06 ml min -1 g -1 at rest and 1.48±0.15 ml min -1 g -1 during dobutamine stress. Oxygen delivery and consumption were 151±13 and 88±15 μl O 2 min -1 g -1 at rest and increased to 291±31 and 216±31 μl O 2 min -1 g -1 , respectively, during pharmacological stress (P 11 C acetate imaging provides the unique capability to study noninvasively determinants of myocardial energy delivery, expenditure, and efficiency. (orig.)

  12. Carbon 14, carbon 13 and oxygen 18 in carbonate sediments from lake Titicaca. Preliminary estimates of sedimentation rate and paleoclimatological attempt

    International Nuclear Information System (INIS)

    Fontes, J.-C.; Boulange, Bruno; Rodrigo, L.-A.

    1981-01-01

    Stable isotope and radiocarbon measurements in carbonates from Titicaca lake indicate equilibrium with lake water and atmospheric CO 2 . Average sedimentation rate is close to 0,5 mm.yr -1 for the last millenium which was marked by large fluctuations of the hydrologic balance and lake level [fr

  13. Carbon 14, carbon 13 and oxygen 18 in carbonate sediments from Lake Titicaca. Preliminary estimates of sedimentation rate and paleoclimatological attempt

    Energy Technology Data Exchange (ETDEWEB)

    Fontes, J.C. (Paris-11 Univ., 91 - Orsay (France)); Boulange, B. (Orstom, 75 - Paris (France)); Rodrigo, L.A. (Universidad Mayor de San Andres, La Paz (Bolivia). Lab. de Fisica Cosmica de Chacaltaya)

    1981-07-06

    Stable isotope and radiocarbon measurements in carbonates from Lake Titicaca indicate equilibrium with lake water and atmospheric CO/sub 2/. Average sedimentation rate is close to 0,5 mm.yr/sup -1/ for the last millenium which was marked by large fluctuations of the hydrologic balance and lake level.

  14. A bio-inspired N-doped porous carbon electrocatalyst with hierarchical superstructure for efficient oxygen reduction reaction

    Science.gov (United States)

    Miao, Yue-E.; Yan, Jiajie; Ouyang, Yue; Lu, Hengyi; Lai, Feili; Wu, Yue; Liu, Tianxi

    2018-06-01

    The bio-inspired hierarchical "grape cluster" superstructure provides an effective integration of one-dimensional carbon nanofibers (CNF) with isolated carbonaceous nanoparticles into three-dimensional (3D) conductive frameworks for efficient electron and mass transfer. Herein, a 3D N-doped porous carbon electrocatalyst consisting of carbon nanofibers with grape-like N-doped hollow carbon particles (CNF@NC) has been prepared through a simple electrospinning strategy combined with in-situ growth and carbonization processes. Such a bio-inspired hierarchically organized conductive network largely facilitates both the mass diffusion and electron transfer during the oxygen reduction reactions (ORR). Therefore, the metal-free CNF@NC catalyst demonstrates superior catalytic activity with an absolute four-electron transfer mechanism, strong methanol tolerance and good long-term stability towards ORR in alkaline media.

  15. Heavily Graphitic-Nitrogen Self-doped High-porosity Carbon for the Electrocatalysis of Oxygen Reduction Reaction

    Science.gov (United States)

    Feng, Tong; Liao, Wenli; Li, Zhongbin; Sun, Lingtao; Shi, Dongping; Guo, Chaozhong; Huang, Yu; Wang, Yi; Cheng, Jing; Li, Yanrong; Diao, Qizhi

    2017-11-01

    Large-scale production of active and stable porous carbon catalysts for oxygen reduction reaction (ORR) from protein-rich biomass became a hot topic in fuel cell technology. Here, we report a facile strategy for synthesis of nitrogen-doped porous nanocarbons by means of a simple two-step pyrolysis process combined with the activation of zinc chloride and acid-treatment process, in which kidney bean via low-temperature carbonization was preferentially adopted as the only carbon-nitrogen sources. The results show that this carbon material exhibits excellent ORR electrocatalytic activity, and higher durability and methanol-tolerant property compared to the state-of-the-art Pt/C catalyst for the ORR, which can be mainly attributed to high graphitic-nitrogen content, high specific surface area, and porous characteristics. Our results can encourage the synthesis of high-performance carbon-based ORR electrocatalysts derived from widely-existed natural biomass.

  16. Proton RBS measurement of the oxygen in heavy-metal oxides

    International Nuclear Information System (INIS)

    Xie, T.; Ryan, S.R.; Fischbeck, H.J.

    1989-01-01

    Although the stoichoimetry of high-T c superconductors is often measured using alpha-particle RBS, the small Rutherford cross section for oxygen relative to the high-Z components makes a determination of the oxygen content difficult. Above 1 MeV, the cross section for proton backscattering from oxygen becomes significantly greater than the Rutherford cross section. Studies of proton backscattering in CuO between 0.6 and 2.0 MeV show that it is possible to measure the oxygen content of high-Z metal oxides. RBS simulations using the Bragg-rule stopping power consistently underestimate the low-energy yield. Scaling the stopping power by a linear function of energy to reduce loss at low energy improves the simulation in CuO, Cu and Au. This general result suggests that the standard RBS simulation procedure may omit some relevant physics. (orig.)

  17. [Peroxynitrite effect on the haemoglobin oxygen affinity in vitro in presence of different partial pressure of carbon dioxide].

    Science.gov (United States)

    Stepuro, T L; Zinchuk, V V

    2011-08-01

    Peroxynitrite (ONOO-) besides its toxic possesses regulatory action that includes the modulation of oxygen binding properties of blood. The aim of this work was to estimate ONOO- effect on the haemoglobin oxygen affinity (HOA) in vitro in presence of different partial pressure of carbon dioxide (CO2). The ONOO- presence in venous blood in conditions of hypercapnia induced oxyhaemoglobin dissociation curve shift leftward while in hypocapnic conditions the result of a different character was obtained. The revealed effect of ONOO- is realized, possibly, through various modifications ofhaemoglobin whose formation is dependent on the CO2 pressure. The ONOO- influences the HOA in different manner that can be important in regulation of blood oxygenation in lungs and maintenance of oxygen consumption in tissues.

  18. Soil-Carbon Measurement System Based on Inelastic Neutron Scattering

    International Nuclear Information System (INIS)

    Orion, I.; Wielopolski, L.

    2002-01-01

    Increase in the atmospheric CO 2 is associated with concurrent increase in the amount of carbon sequestered in the soil. For better understanding of the carbon cycle it is imperative to establish a better and extensive database of the carbon concentrations in various soil types, in order to develop improved models for changes in the global climate. Non-invasive soil carbon measurement is based on Inelastic Neutron Scattering (INS). This method has been used successfully to measure total body carbon in human beings. The system consists of a pulsed neutron generator that is based on D-T reaction, which produces 14 MeV neutrons, a neutron flux monitoring detector and a couple of large NaI(Tl), 6'' diameter by 6'' high, spectrometers [4]. The threshold energy for INS reaction in carbon is 4.8 MeV. Following INS of 14 MeV neutrons in carbon 4.44 MeV photons are emitted and counted during a gate pulse period of 10 μsec. The repetition rate of the neutron generator is 104 pulses per sec. The gamma spectra are acquired only during the neutron generator gate pulses. The INS method for soil carbon content measurements provides a non-destructive, non-invasive tool, which can be optimized in order to develop a system for in field measurements

  19. Carbon-Coated Perovskite BaMnO3 Porous Nanorods with Enhanced Electrocatalytic Perporites for Oxygen Reduction and Oxygen Evolution

    International Nuclear Information System (INIS)

    Xu, Yujiao; Tsou, Alvin; Fu, Yue; Wang, Jin; Tian, Jing-Hua; Yang, Ruizhi

    2015-01-01

    A thin carbon layer has been introduced to coat on the perovskite BaMnO 3 nanorods by a facile method, which exhibit significantly enhanced electrocatalytic activity for both the ORR and OER with excellent stability. - Highlights: • A non-rare-earth element based perovskite BaMnO 3 nanorods as an active electrocatalyst for the ORR and OER have been prepared and investigated for the first time. • A thin carbon-coating layer with thickness of approximately 10 nm has been successfully introduced to enhance the electrical conductivity and the electrocatalytic activities of the bare perovskite for both ORR and OER. • The stabilities of bare BaMnO 3 nanorods for both ORR and OER have also been improved dramatically with the help of carbon coating, especially for the OER process. - Abstract: Highly efficient, low-cost catalysts, especially with bifunctional electrocatalytic capabilities for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are vital for the wide commercialization of fuel cells and metal-air batteries. In this study, BaMnO 3 - a non-rare-earth element based perovskite nanorods have been prepared and investigated for the first time, and a thin carbon-coating with a thickness of approximately 10 nm has been successfully introduced to enhance the electrical conductivity of the bare perovskite. Electrochemical tests reveal that bare BaMnO 3 nanorods exhibit very good catalytic activity. More interestingly, a remarkably enhanced ORR activity for the perovskite BaMnO 3 nanorods was observed after coating with a thin layer of carbon, which dominated with a direct four-electron pathway. Meanwhile, the OER process has also been enhanced extraordinarily with the carbon-coating, reaching a maximum of 14.8 mA cm −2 at 1.0 V (vs. Ag/AgCl), which is far superior to both the bare BaMnO 3 nanorods and commercial Pt/C (20 wt%) catalysts. Furthermore, the stabilities of bare BaMnO 3 nanorods for both ORR and OER have also been improved

  20. Spontaneous Oxygen Isotope Exchange between Carbon Dioxide and Oxygen-Containing Minerals: Do the Minerals "breathe" CO2?

    Czech Academy of Sciences Publication Activity Database

    Civiš, Svatopluk; Bouša, Milan; Zukal, Arnošt; Knížek, Antonín; Kubelík, Petr; Rojík, P.; Nováková, Jana; Ferus, Martin

    2016-01-01

    Roč. 120, č. 1 (2016), s. 508-516 ISSN 1932-7447 R&D Projects: GA MŠk LD14115; GA MŠk(CZ) LD13060; GA ČR(CZ) GA14-12010S Grant - others:COST(XE) CM1104 Institutional support: RVO:61388955 Keywords : Absorption spectroscopy * Infrared spectrometers * Oxygen Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.536, year: 2016

  1. Synthesis and reactivity of compounds containing ruthenium-carbon, -nitrogen, and -oxygen bonds

    International Nuclear Information System (INIS)

    Hartwig, J.F.

    1990-12-01

    The products and mechanisms of the thermal reactions of several complexes of the general structure (PMe 3 ) 4 Ru(X)(Y) and (DMPM) 2 Ru(X)(Y) where X and Y are hydride, aryl, and benzyl groups, have been investigated. The mechanism of decomposition depends critically on the structure of the complex and the medium in which the thermolysis is carried out. The alkyl hydride complexes are do not react with alkane solvent, but undergo C-H activation processes with aromatic solvents by several different mechanisms. Thermolysis of (PMe 3 ) 4 Ru(Ph)(Me) or (PMe 3 ) 4 Ru(Ph) 2 leads to the ruthenium benzyne complex (PMe 3 ) 4 Ru(η 2 -C 6 H 4 ) (1) by a mechanism which involves reversible dissociation of phosphine. In many ways its chemistry is analogous to that of early rather than late organo transition metal complexes. The synthesis, structure, variable temperature NMR spectroscopy and reactivity of ruthenium complexes containing aryloxide or arylamide ligands are reported. These complexes undergo cleavage of a P-C bond in coordinated trimethylphosphine, insertion of CO and CO 2 and hydrogenolysis. Mechanistic studies on these reactions are described. The generation of a series of reactive ruthenium complexes of the general formula (PMe 3 ) 4 Ru(R)(enolate) is reported. Most of these enolates have been shown to bind to the ruthenium center through the oxygen atom. Two of the enolate complexes 8 and 9 exist in equilibrium between the O- and C-bound forms. The reactions of these compounds are reported, including reactions to form oxygen-containing metallacycles. The structure and reactivity of these ruthenium metallacycles is reported, including their thermal chemistry and reactivity toward protic acids, electrophiles, carbon monoxide, hydrogen and trimethylsilane. 243 refs., 10 tabs

  2. Synthesis and reactivity of compounds containing ruthenium-carbon, -nitrogen, and -oxygen bonds

    Energy Technology Data Exchange (ETDEWEB)

    Hartwig, J.F.

    1990-12-01

    The products and mechanisms of the thermal reactions of several complexes of the general structure (PMe{sub 3}){sub 4}Ru(X)(Y) and (DMPM){sub 2}Ru(X)(Y) where X and Y are hydride, aryl, and benzyl groups, have been investigated. The mechanism of decomposition depends critically on the structure of the complex and the medium in which the thermolysis is carried out. The alkyl hydride complexes are do not react with alkane solvent, but undergo C-H activation processes with aromatic solvents by several different mechanisms. Thermolysis of (PMe{sub 3}){sub 4}Ru(Ph)(Me) or (PMe{sub 3}){sub 4}Ru(Ph){sub 2} leads to the ruthenium benzyne complex (PMe{sub 3}){sub 4}Ru({eta}{sup 2}-C{sub 6}H{sub 4}) (1) by a mechanism which involves reversible dissociation of phosphine. In many ways its chemistry is analogous to that of early rather than late organo transition metal complexes. The synthesis, structure, variable temperature NMR spectroscopy and reactivity of ruthenium complexes containing aryloxide or arylamide ligands are reported. These complexes undergo cleavage of a P-C bond in coordinated trimethylphosphine, insertion of CO and CO{sub 2} and hydrogenolysis. Mechanistic studies on these reactions are described. The generation of a series of reactive ruthenium complexes of the general formula (PMe{sub 3}){sub 4}Ru(R)(enolate) is reported. Most of these enolates have been shown to bind to the ruthenium center through the oxygen atom. Two of the enolate complexes 8 and 9 exist in equilibrium between the O- and C-bound forms. The reactions of these compounds are reported, including reactions to form oxygen-containing metallacycles. The structure and reactivity of these ruthenium metallacycles is reported, including their thermal chemistry and reactivity toward protic acids, electrophiles, carbon monoxide, hydrogen and trimethylsilane. 243 refs., 10 tabs.

  3. Integrating the pulse of the riverscape and landscape: modelling stream metabolism using continuous dissolved oxygen measurements

    Science.gov (United States)

    Soulsby, C.; Birkel, C.; Malcolm, I.; Tetzlaff, D.

    2013-12-01

    Stream metabolism is a fundamental pulse of the watershed which reflects both the in-stream environment and its connectivity with the wider landscape. We used high quality, continuous (15 minute), long-term (>3 years) measurement of stream dissolved oxygen (DO) concentrations to estimate photosynthetic productivity (P) and system respiration (R) in forest and moorland reaches of an upland stream with peaty soils. We calibrated a simple five parameter numerical oxygen mass balance model driven by radiation, stream and air temperature, stream depth and re-aeration capacity. This used continuous 24-hour periods for the whole time series to identify behavioural simulations where DO simulations were re-produced sufficiently well to be considered reasonable representations of ecosystem functioning. Results were evaluated using a seasonal Regional Sensitivity Analysis and a co-linearity index for parameter sensitivity. This showed that >95 % of the behavioural models for the moorland and forest sites were identifiable and able to infer in-stream processes from the DO time series for almost half of all measured days at both sites. Days when the model failed to simulate DO levels successfully provided invaluable insight into time periods when other factors are likely to disrupt in-stream metabolic processes; these include (a) flood events when scour reduces the biomass of benthic primary producers, (b) periods of high water colour in higher summer/autumn flows and (c) low flow periods when hyporheic respiration is evident. Monthly P/R ratios <1 indicate a heterotrophic system with both sites exhibiting similar temporal patterns; with a maximum in February and a second peak during summer months. However, the estimated net ecosystem productivity (NPP) suggests that the moorland reach without riparian tree cover is likely to be a much larger source of carbon to the atmosphere (122 mmol C m-2 d-1) compared to the forested reach (64 mmol C m-2 d-1). The study indicates the value

  4. Measuring the Carbon Intensity of the South African Economy

    DEFF Research Database (Denmark)

    Arndt, Channing; Davies, Rob; Makrelov, Konstantin

    2013-01-01

    We estimate the carbon intensity of industries, products and households in South Africa using data from a high resolution supply-use table. Direct and indirect carbon usage is measured using multiplier methods that capture inter-industry linkages and multi-product supply chains. Carbon intensity ...... or poorer households. Seven percent of emissions arise through marketing margins, implying that carbon pricing should be accompanied by supporting public policies and investments.......We estimate the carbon intensity of industries, products and households in South Africa using data from a high resolution supply-use table. Direct and indirect carbon usage is measured using multiplier methods that capture inter-industry linkages and multi-product supply chains. Carbon intensity...... is found to be high for exports but low for major employing sectors. Middle-income households are the most carbon-intensive consumers. These results suggest that carbon pricing policies (without border tax adjustments) would adversely affect export earnings, but should not disproportionately hurt workers...

  5. Measurements of electron attachment by oxygen molecule in proportional counter

    Energy Technology Data Exchange (ETDEWEB)

    Tosaki, M., E-mail: tosaki.mitsuo.3v@kyoto-u.ac.jp [Radioisotope Research Center, Kyoto University, Kyoto 606-8501 (Japan); Kawano, T. [National Institute for Fusion Science, 322-6 Oroshi, Toki 509-5292 (Japan); Isozumi, Y. [Radioisotope Research Center, Kyoto University, Kyoto 606-8501 (Japan)

    2013-11-15

    We present pulse height measurements for 5-keV Auger electrons from a radioactive {sup 55}Fe source mounted at the inner cathode surface of cylindrical proportional counter, which is operated with CH{sub 4} admixed dry air or N{sub 2}. A clear shift of the pulse height has been observed by varying the amount of the admixtures; the number of electrons, created in the primary ionization by Auger electrons, is decreased by the electron attachment of the admixtures during their drift from the place near the source to the anode wire. The large gas amplification (typically 10{sup 4}) in the secondary ionization of proportional counter makes it possible to investigate a small change in the number of primary electrons. The electron attenuation cross-section of O{sub 2} has been evaluated by analyzing the shifts of the pulse height caused by the electron attachment to dry air and N{sub 2}.

  6. Standardization for oxygen isotope ratio measurement - still an unsolved problem.

    Science.gov (United States)

    Kornexl; Werner; Gehre

    1999-07-01

    Numerous organic and inorganic laboratory standards were gathered from nine European and North American laboratories and were analyzed for their delta(18)O values with a new on-line high temperature pyrolysis system that was calibrated using Vienna standard mean ocean water (VSMOW) and standard light Antartic precipitation (SLAP) internationally distributed reference water samples. Especially for organic materials, discrepancies between reported and measured values were high, ranging up to 2 per thousand. The reasons for these discrepancies are discussed and the need for an exact and reliable calibration of existing reference materials, as well as for the establishment of additional organic and inorganic reference materials is stressed. Copyright 1999 John Wiley & Sons, Ltd.

  7. Carbon supported Pd-Co-Mo alloy as an alternative to Pt for oxygen reduction in direct ethanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Ch. Venkateswara [National Centre for Catalysis Research, Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, TN (India); Viswanathan, B., E-mail: bvnathan@acer.iitm.ernet.i [National Centre for Catalysis Research, Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, TN (India)

    2010-03-01

    Carbon black (CDX975) supported Pd and Pd-Co-Mo alloy nanoparticles are prepared by the reduction of metal precursors with hydrazine in reverse microemulsion of water/Triton-X-100/propanol-2/cyclohexane. The as-synthesized Pd-Co-Mo/CDX975 is heat treated at 973, 1073 and 1173 K to promote alloy formation. The prepared materials are characterized by powder XRD and EDX. Face-centred cubic structure of Pd is evident from XRD. The chemical composition of the respective elements in the catalysts is evaluated from the EDX analysis and observed that it is in good agreement with initial metal precursor concentrations. Oxygen reduction measurements performed by linear sweep voltammetry indicate the good catalytic activity of Pd-Co-Mo alloys compared to Pd. This is due to the suppression of (hydr)oxy species on Pd surface by the presence of alloying elements, Co and Mo. Among the investigated catalysts, heat-treated Pd-Co-Mo/CDX975 at 973 K exhibited good ORR activity compared to the catalysts heat treated at 1073 and 1173 K. This is due to the small crystallite size and high surface area. Rotating disk electrode (RDE) measurements indicated the comparable ORR activity of heat-treated Pd-Co-Mo/CDX975 at 973 K with that of commercial Pt/C. Kinetic analysis reveals that the ORR on Pd-Co-Mo/CDX975 follows the four-electron pathway leading to water. Moreover, Pd-Co-Mo/CDX975 exhibited substantially higher ethanol tolerance during the ORR than Pt/C. Good dispersion of metallic nanoparticles on the carbon support is observed from HRTEM images. Single-cell direct ethanol fuel cell tests indicated the comparable performance of Pd-Co-Mo/CDX975 with that of commercial Pt/C. Stability under DEFC operating conditions for 50 h indicated the good stability of Pd-Co-Mo/CDX975 compared with that of Pt/C.

  8. Measurements of oxygenated volatile organic compounds in the oil sands region of Alberta

    Science.gov (United States)

    Moussa, S. G.; Leithead, A.; Li, S. M.; Gordon, M.; Hayden, K. L.; Wang, D. K.; Staebler, R. M.; Liu, P.; O'Brien, J.; Mittermeier, R.; Liggio, J.

    2014-12-01

    Oxygenated volatile organic compounds (OVOCs) are ubiquitous in the atmosphere, and represent an important fraction of volatile organic compounds. Additionally some OVOC species may pose health risks. OVOCs can affect the oxidative and radiative budget of the atmosphere since they are precursors to ground level ozone, hydroxyl radicals and secondary organic aerosols (SOA). OVOCs such as methanol, formaldehyde, acetaldehyde, acetone, crotonaldehyde, methylvinylketone (MVK), methylethylketone (MEK) and acrolein can be emitted from anthropogenic and biogenic sources. Additionally, they are the secondary products of the photo-oxidation of hydrocarbons (biogenic and anthropogenic). Understanding the magnitude of these sources is a prerequisite for accurate representations of radical cycling, ozone production and SOA formation in air quality models. The sources of OVOCs in the Alberta Oil Sands (OS) region have not previously been well characterized. In the summer of 2013, airborne measurements of various OVOCs were made in the Athabasca oil sands region between August 13 and September 7, 2013. Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) was used to measure methanol, formaldehyde, acetaldehyde, acetone, crotonaldehyde, MVK, MEK, acrolein as well as other hydrocarbons. Emission ratios (ER) for several OVOCs (relative to carbon monoxide; CO) were used to estimate direct anthropogenic emissions from OS industrial sources, while the calculated OH radical exposures were used to estimate the production and removal of secondary anthropogenic OVOCs. The results indicate that OVOCs such as acetaldehyde, crotonaldehyde and MVK have both primary and secondary anthropogenic and biogenic sources. However, species such as methanol and acrolein are from biogenic and anthropogenic sources, respectively. The results of this work will help to characterize sources of OVOCs and the factors influencing their atmospheric fate in the Oil Sands region.

  9. Dissolved inorganic carbon, total alkalinity, pH, dissolved oxygen, and nutrients collected from profile, discrete sampling, and time series observations using CTD, Niskin bottle, and other instruments from R/V Gulf Challenger near a buoy off the coast of New Hampshire, U.S. in the Gulf of Maine from 2011-01-11 to 2015-11-18 (NCEI Accession 0142327)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains discrete measurements of dissolved inorganic carbon, total alkalinity, pH, dissolved oxygen, and nutrients collected at the buoy off...

  10. Diurnal dynamics of oxygen and carbon dioxide concentrations in shoots and rhizomes of a perennial in a constructed wetland indicate down-regulation of below ground oxygen consumption

    Czech Academy of Sciences Publication Activity Database

    Fausser, A. C.; Dušek, Jiří; Čížková, Hana; Kazda, M.

    2016-01-01

    Roč. 8, JUL (2016), č. článku plw025. ISSN 2041-2851 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA MŠk(CZ) LM2010007 Institutional support: RVO:86652079 Keywords : typha-latifolia l * internal gas-transport * phragmites-australis * convective throughflow * pressurized ventilation * angustifolia l * ex steud * roots * flow * respiration * Aeration * constructed wetland * in-situ field study * internal carbon dioxide * internal oxygen dynamics * Phragmites australis Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 2.238, year: 2016

  11. Isotopic strontium, carbon and oxygen study on neoproterozoic marbles from Sierra de Umango, Andean Foreland, Argentina

    International Nuclear Information System (INIS)

    Varela, R; Valencio, S.; Ramos, A; Sato, K; Gonzalez, P; Panarello, H; Roverano, D

    2001-01-01

    The Umango Hill (La Rioja Province, 29 o 00'S-68 o 40'W) is one of the mountain blocks of Sierras Pampeanas Occidentales (Caminos, 1979), bounded by thrust faults and surrounded by Upper Devonian to Tertiary marine and continental sedimentites. The exposed crystalline basement is composed of basic igneous rocks and a siliciclastic-limestone sequence, both affected by amphibolite facies metamorphic peak. In the southern area (Juchi creek), the metamorphic complex carries relics of granitic orthogneisses, with Rb/Sr and U/Pb dates of ∼1000 Ma (Varela et al., 1996). These ancient inliers were asigned to a Mesoproterozoic Grenville Orogenic Cycle. Granitic bodies, intrusives at different ages in the Metamorphic Complex, have also been distinguished. The most ancient is El Penon Granite, with 469±9 Ma Rb/Sr age (Varela et al., 2000) and 523±26 Ma U/Pb zircon age (unpublished data). In this way it is possible to point out broadly that the siliciclastic-limestone sequence belongs to the Neoproterozoic-Early Palaeozoic times. It was a platform cover over grenvillian cratonic basement. The metamorphism and deformation, we understand, took place in the Early Palaeozoic, related to the Pampean-Famatinian Orogenic Cycle. In this work, compositional and isotopic data of Strontium ( 87 Sr/ 86 Sr), Carbon (δ 13 Cv PDB ) and Oxygen (δ 18 Ov PDB ) of the marbles derived from the siliciclastic-limestone sequence are presented. The results are interpreted and correlated with the temporal variation curves of 87 Sr/ 86 Sr and δ 13 C from Neoproterozoic marine carbonates (Jacobsen and Kaufman, 1999) (au)

  12. Effects of spinal immobilization at a 20° angle on cerebral oxygen saturations measured by INVOS™.

    Science.gov (United States)

    Aksel, Gökhan

    2018-01-01

    In this study, we aimed to investigate whether performing the immobilization at 20° instead of 0° changes cerebral oxygenation. 33 volunteers were put in a hard cervical collar and backboard at 0° and immobilized for 30min. The cerebral oxygen saturations of the volunteers were measured at 1, 5, and 30min after the start of the procedure (Group 1). The volunteers were asked to return the day after the Group 1 procedure but at the same time. Serial cerebral oxygen saturations were obtained at the same time intervals as in Group 1, but for Group 2, the backboard was set to 20°. When the cerebral oxygen saturations of the two groups were compared, there was a slight decrease when the backboard position was changed from 0° to 20°, but it was not statistically significant (P=0.220 and P=0.768, respectively). The results revealed that immobilizing the patients with a spinal backboard at 20° instead of 0° did not alter the cerebral oxygen saturations. Our study results revealed that spinal immobilization at 20°, which was a new suggestion for spinal immobilization following a report that this position reduced the decrease in pulmonary function secondary to spinal immobilization, did not alter the cerebral oxygenation, so this suggestion is safe at least from the standpoint of cerebral oxygenation. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Chemical forms of the fluorine, chlorine, oxygen and carbon in coal fly ash and their correlations with mercury retention

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Shuang [State Key Laboratory of Environmental Criteria and Risk Assessment (China); Research Academy of Environmental Sciences, Beijing 100012 (China); Shu, Yun [Research Academy of Environmental Sciences, Beijing 100012 (China); Li, Songgeng, E-mail: sgli@ipe.ac.cn [State Key Laboratory of Multi-phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Tian, Gang; Huang, Jiayu [Research Academy of Environmental Sciences, Beijing 100012 (China); Zhang, Fan, E-mail: zhangfan5188@vip.sina.com [Research Academy of Environmental Sciences, Beijing 100012 (China)

    2016-01-15

    Highlights: • Chlorine and fluorine are present mainly in an inorganic form on ash. • Correlations of carbon–oxygen complexes with mercury retention are established. • Concentrations of carbon–oxygen complexes on ash are related to coal type. • No effect of fluorine on mercury retention is observed. • Chlorine, fluorine and carbon in ash are enriched on surface. - Abstract: Fly ashes recovered from the particulate control devices at six pulverized coal boiler unites of China, are studied using an X-ray photoelectron spectroscopy (XPS) with a particular focus on the functionalities of fluorine (F), chlorine (Cl), carbon and oxygen on fly ash. It is found that the inorganic forms of F and Cl are predominant on the ash surface in comparison with their organics, and the proportion of organic Cl is relatively higher than that of organic F. Similar results are also obtained in the bulk by correlating the F and Cl contents with those of the unburnt carbon and other compositions in ash. Strong correlations of mercury retention with surface carbon–oxygen functional groups indicate that the C=O, OH/C−O and (O−C=O)−O on surface are of significant importance for mercury retention in fly ash. Their surface concentrations are related to coal type. The presence of Cl in fly ash helps with mercury retention. No obvious effect of F is observed.

  14. Active packaged lamb with oxygen scavenger/carbon dioxide emitter sachet: physical-chemical and microbiological stability during refrigerated storage

    Directory of Open Access Journals (Sweden)

    Marco Antonio Trindade

    2013-09-01

    Full Text Available Lamb meat has been commercialized in Brazil almost exclusively as a frozen product due to the longer shelf life provided by freezing when compared to refrigeration. However, as a result of the current trend of increased demand for convenience products, a need has emerged for further studies to facilitate the marketing of refrigerated lamb cuts. The aim of the present study was to evaluate the contribution of active packaging technology in extending the shelf life of lamb loins (Longissimus lumborum stored under refrigeration (1±1 ° C when compared to the traditional vacuum packaging. For this purpose, two kinds of sachets were employed: oxygen scavenger sachet and oxygen scavenger/carbon dioxide emitter sachet. Experiments were conducted in three treatments: 1 Vacuum (Control, 2 Vacuum + oxygen scavenger sachet and 3 Vacuum + oxygen scavenger/carbon dioxide emitter sachet. Microbiological (counts of anaerobic psychrotrophs, coliform at 45 ° C, coagulase-positive staphylococci, Salmonella and lactic acid bacteria and physical-chemical (thiobarbituric acid reactive substances, objective color, pH value, water loss from cooking and shear force analyses were carried out weekly for a total storage period of 28 days. The experiment was performed three times for all treatments. Results showed that the lamb meat remained stable with respect to the majority of the evaluated physical and chemical indexes and remained within the standards established by Brazilian legislation for pathogenic microorganisms throughout the storage period in all three packaging systems. However, all treatments presented elevated counts of anaerobic psychrotrophic microorganisms and lactic acid bacteria, reaching values above 10(7 CFU/g at 28 days of storage. Thus, under the conditions tested, neither the oxygen scavenger sachet nor the dual function sachet (oxygen scavenger/carbon dioxide emitter were able to extend the shelf life of refrigerated lamb loin when added to this

  15. High time resolution measurements of the thermosphere from Fabry-Perot Interferometer measurements of atomic oxygen

    Directory of Open Access Journals (Sweden)

    E. A. K. Ford

    2007-06-01

    Full Text Available Recent advances in the performance of CCD detectors have enabled a high time resolution study of the high latitude upper thermosphere with Fabry-Perot Interferometers (FPIs to be performed. 10-s integration times were used during a campaign in April 2004 on an FPI located in northern Sweden in the auroral oval. The FPI is used to study the thermosphere by measuring the oxygen red line emission at 630.0 nm, which emits at an altitude of approximately 240 km. Previous time resolutions have been 4 min at best, due to the cycle of look directions normally observed. By using 10 s rather than 40 s integration times, and by limiting the number of full cycles in a night, high resolution measurements down to 15 s were achievable. This has allowed the maximum variability of the thermospheric winds and temperatures, and 630.0 nm emission intensities, at approximately 240 km, to be determined as a few minutes. This is a significantly greater variability than the often assumed value of 1 h or more. A Lomb-Scargle analysis of this data has shown evidence of gravity wave activity with waves with short periods. Gravity waves are an important feature of mesosphere-lower thermosphere (MLT dynamics, observed using many techniques and providing an important mechanism for energy transfer between atmospheric regions. At high latitudes gravity waves may be generated in-situ by localised auroral activity. Short period waves were detected in all four clear nights when this experiment was performed, in 630.0 nm intensities and thermospheric winds and temperatures. Waves with many periodicities were observed, from periods of several hours, down to 14 min. These waves were seen in all parameters over several nights, implying that this variability is a typical property of the thermosphere.

  16. The Choroidal Eye Oximeter - An instrument for measuring oxygen saturation of choroidal blood in vivo

    Science.gov (United States)

    Laing, R. A.; Danisch, L. A.; Young, L. R.

    1975-01-01

    The Choroidal Eye Oximeter is an electro-optical instrument that noninvasively measures the oxygen saturation of choroidal blood in the back of the human eye by a spectrophotometric method. Since choroidal blood is characteristic of blood which is supplied to the brain, the Choroidal Eye Oximeter can be used to monitor the amount of oxygen which is supplied to the brain under varying external conditions. The instrument consists of two basic systems: the optical system and the electronic system. The optical system produces a suitable bi-chromatic beam of light, reflects this beam from the fundus of the subject's eye, and onto a low-noise photodetector. The electronic system amplifies the weak composite signal from the photodetector, computes the average oxygen saturation from the area of the fundus that was sampled, and displays the value of the computed oxygen saturation on a panel meter.

  17. Carbon, hydrogen oxygen isotope studies on imbedded old tree ring and paleoclimate reconstruction

    International Nuclear Information System (INIS)

    Sun Yanrong; Mu Zhiguo; Cui Haiting

    2002-01-01

    Tree ring is a kind of natural archives, on which the isotopic analysis is important to study global climate and environmental change. The authors mainly provide a comprehensive introduction to the fractionation models of carbon, hydrogen and oxygen isotope in plants, their research technique and the extract methods from cellulose. That results show isotopic tracer can record the message of climatic variation and has become a powerful tool for paleoclimate reconstruction and for the modern environment changing research. Especially studying on PAGES. the cellulose isotopic analyses of imbedded old tree ring have become the mainly quantitative means of environmental evolvement. In addition, China is a typical monsoon country, research in tree ring stable isotope seasonal variation can give a lot of important information on that. Up to now, the research techniques and works on tree ring in China are still in its earlier stage, and remain many limitations. It needs further accumulate basic research materials, intensity regional contrast and intercross studies on relative subjects

  18. Study of the carbon and oxygen isotopic compositions in marine shells of Salvador-Bahia, Brazil

    International Nuclear Information System (INIS)

    Freitas, J.C.B. de.

    1977-01-01

    The carbon and oxygen isotopic composition of 68 samples of marine shells from the region of Salvador was determined. These samples are from points on the open coast and in the interior of the Todos os Santos Bay and they are composed in part by recent specimens and in part by old specimens taken from Quaternary sediments. The results for δ 18 O are in the range of -2,83per mille to + 1,21per mille (PDB) and for δ 13 C in the range of -3,10per mille to +2,63per mille (PDB). The reults for the recent shells from the interior of the Todos os Santos Bay show variations in the δ 13 C values associated to the dominance of organic matter in some regions. For the old samoles, gathered in te variations in the δ 13 C values was associated to the existence in points of that region of deposits of fluvio-lagunar sediments, originated during the last marine transgression. It was identified, for a few species with the same age and location, the effect of biological fractionations. Nevertheless, the observed dominant factor on the isotopic differentiation was the environmental fractionation. (Author) [pt

  19. Functionalised Oximes: Emergent Precursors for Carbon-, Nitrogen- and Oxygen-Centred Radicals

    Directory of Open Access Journals (Sweden)

    John C. Walton

    2016-01-01

    Full Text Available Oxime derivatives are easily made, are non-hazardous and have long shelf lives. They contain weak N–O bonds that undergo homolytic scission, on appropriate thermal or photochemical stimulus, to initially release a pair of N- and O-centred radicals. This article reviews the use of these precursors for studying the structures, reactions and kinetics of the released radicals. Two classes have been exploited for radical generation; one comprises carbonyl oximes, principally oxime esters and amides, and the second comprises oxime ethers. Both classes release an iminyl radical together with an equal amount of a second oxygen-centred radical. The O-centred radicals derived from carbonyl oximes decarboxylate giving access to a variety of carbon-centred and nitrogen-centred species. Methods developed for homolytically dissociating the oxime derivatives include UV irradiation, conventional thermal and microwave heating. Photoredox catalytic methods succeed well with specially functionalised oximes and this aspect is also reviewed. Attention is also drawn to the key contributions made by EPR spectroscopy, aided by DFT computations, in elucidating the structures and dynamics of the transient intermediates.

  20. Synthesis of Fe nanoparticles on polyaniline covered carbon nanotubes for oxygen reduction reaction

    Science.gov (United States)

    Hu, Tian-Hang; Yin, Zhong-Shu; Guo, Jian-Wei; Wang, Cheng

    2014-12-01

    Fe nanoparticles immobilized on polyaniline-covered carbon nanotube (CNT) surfaces (Fe NPs-PANI/CNT) are prepared by reducing FeCl3 in the mixing solution of aniline and CNT. Significantly, the structure of such composites can be effectively optimized by pretreating FeCl3 with sodium citrate (CA). In the absence of CNTs, we found these two routes have large differences in reduction behaviors and different PANI states with varied conductivities. Therefore, the self-assembly mechanism in the preparation is proposed and the controlled self-assembly manner in the pretreating route is disclosed. Under acid condition, both catalysts demonstrate high oxygen reduction reaction (ORR) activity with four-electron pathway, and high electrochemical durability, revealing a promising application in the proton exchange membrane fuel cells. However, the high Tafel slopes relating to the surface red-ox couple and porous conductivity are still the main obstacles to improve their ORR dynamic, and more efforts on these aspects are needed to drive non-noble catalyst application in future.

  1. Selection criteria utilized for hyperbaric oxygen treatment of carbon monoxide poisoning.

    Science.gov (United States)

    Hampson, N B; Dunford, R G; Kramer, C C; Norkool, D M

    1995-01-01

    Medical directors of North American hyperbaric oxygen (HBO) facilities were surveyed to assess selection criteria applied for treatment of acute carbon monoxide (CO) poisoning within the hyperbaric medicine community. Responses were received from 85% of the 208 facilities in the United States and Canada. Among responders, 89 monoplace and 58 multiplace chamber facilities treat acute CO poisoning, managing a total of 2,636 patients in 1992. A significant majority of facilities treat CO-exposed patients with coma (98%), transient loss of consciousness (LOC) (77%), ischemic changes on electrocardiogram (91%), focal neurologic deficits (94%), or abnormal psychometric testing (91%), regardless of carboxyhemoglobin (COHb) level. Although 92% would use HBO for a patient presenting with headache, nausea, and COHb 40%, only 62% of facilities utilize a specified minimum COHb level as the sole criterion for HBO therapy of an asymptomatic patient. When COHb is used as an independent criterion to determine HBO treatment, the level utilized varies widely between institutions. Half of responding facilities place limits on the delay to treatment for patients with only transient LOC. Time limits are applied less often in cases with persistent neurologic deficits. While variability exists, majority opinions can be derived for many patient selection criteria regarding the use of HBO in acute CO poisoning.

  2. Requests for emergency hyperbaric oxygen treatment for carbon monoxide poisoning in Ankara, Turkey.

    Science.gov (United States)

    Özgök-Kangal, Münïre Kübra; Karatop-Cesur, Iclal; Akcali, Gökhan; Yildiz, Senol; Uzun, Günalp

    2016-09-01

    Carbon monoxide (CO) poisoning is common in Turkey. Our department is the main provider of emergency hyperbaric oxygen therapy (HBOT) in Ankara and neighboring cities. In this study, we analyzed the characteristics of CO-poisoned patients who were referred by phone to our department for emergency HBOT. We retrospectively reviewed the records of phone consultations with emergency departments regarding the need for treatment of CO-poisoned patients with HBOT between 14 January 2014 and 14 January 2015. The following information was extracted from medical records: age, gender, CO source, exposure duration, carboxyhemoglobin (COHb) level, symptoms, electrocardiography (ECG) findings, cardiac enzymes, pregnancy, the distance of referring hospital to our centre, time between admission and consultation and HBOT decision. Over the one-year period, 562 patients with CO poisoning were referred for HBOT. We recommended HBOT for 289 (51%) patients. HBOT was recommended for 58% (n = 194) of the patients with COHb ≥ 25%, 72% (n = 163) of the patients with a history of syncope, 67% (n = 35) of the patients with ECG abnormality, and 67% (n = 14) of pregnant patients. Patients for whom HBOT was not recommended despite having positive signs of severe poisoning were referred significantly later compared to patients for whom HBOT was recommended. We found that the duration from admission to an emergency department to HBOT consultation affected our decision-making.

  3. High Oxygen Reduction Reaction Performances of Cathode Materials Combining Polyoxometalates, Coordination Complexes, and Carboneous Supports.

    Science.gov (United States)

    Zhang, Shuangshuang; Oms, Olivier; Hao, Long; Liu, Rongji; Wang, Meng; Zhang, Yaqin; He, Hong-Yan; Dolbecq, Anne; Marrot, Jérôme; Keita, Bineta; Zhi, Linjie; Mialane, Pierre; Li, Bin; Zhang, Guangjin

    2017-11-08

    A series of carbonaceous-supported precious-metal-free polyoxometalate (POM)-based composites which can be easily synthesized on a large scale was shown to act as efficient cathode materials for the oxygen reduction reaction (ORR) in neutral or basic media via a four-electron mechanism with high durability. Moreover, exploiting the versatility of the considered system, its activity was optimized by the judicious choice of the 3d metals incorporated in the {(PW 9 ) 2 M 7 } (M = Co, Ni) POM core, the POM counterions and the support (thermalized triazine-based frameworks (TTFs), fluorine-doped TTF (TTF-F), reduced graphene oxide, or carbon Vulcan XC-72. In particular, for {(PW 9 ) 2 Ni 7 }/{Cu(ethylenediamine) 2 }/TTF-F, the overpotential required to drive the ORR compared well with those of Pt/C. This outstanding ORR electrocatalytic activity is linked with two synergistic effects due to the binary combination of the Cu and Ni centers and the strong interaction between the POM molecules and the porous and highly conducting TTF-F framework. To our knowledge, {(PW 9 ) 2 Ni 7 }/{Cu(ethylenediamine) 2 }/TTF-F represents the first example of POM-based noble-metal-free ORR electrocatalyst possessing both comparable ORR electrocatalytic activity and much higher stability than that of Pt/C in neutral medium.

  4. Inorganic Carbon and Oxygen Dynamics in a Marsh-dominated Estuary

    Science.gov (United States)

    Wang, S. R.; Di Iorio, D.; Cai, W. J.; Hopkinson, C.

    2017-12-01

    A free-water mass balance-based study was conducted to address the rate of metabolism and net carbon exchange for the tidal wetland and estuarine portion of the coastal ocean and the uncertainties associated with this approach were assessed. Open water diurnal O2 and dissolved inorganic carbon (DIC) were measured seasonally in a salt marsh-estuary in Georgia, U.S.A. with a focus on the marsh-estuary linkage associated with tidal flooding. We observed that the overall estuarine system was a net source of CO2 to the atmosphere and coastal ocean and a net sink for oceanic and atmospheric O2. Rates of metabolism were extremely high, with respiration (43 mol m-2 yr-1) greatly exceeding gross primary production (28 mol m-2 yr-1), such that the overall system was net heterotrophic. Metabolism measured with DIC were higher than with O2, which we attribute to high rates of anaerobic respiration and reduced sulfur storage in salt marsh sediments, and we assume substantial levels of anoxygenic photosynthesis. We found gas exchange from a flooded marsh is substantial, accounting for about 28% of total O2 and CO2 air-water exchange. A significant percentage of the overall estuarine aquatic metabolism is attributable to metabolism of marsh organisms during inundation. Our study suggests not rely on oceanographic stoichiometry to convert from O2to C based measurements when constructing C balances for the coastal ocean. We also suggest eddy covariance measurements of salt marsh net ecosystem exchange underestimate net ecosystem production as they do not account for lateral DIC exchange associated with marsh tidal inundation. With the increase of global temperature and sea level rise, salt marshes are likely to export more inorganic carbon to the atmosphere and the coastal ocean due to the decrease of solubility, the increase of aquatic and benthic metabolic activities and the longer marsh inundation.

  5. New principle for measuring arterial blood oxygenation, enabling motion-robust remote monitoring

    OpenAIRE

    Mark van Gastel; Sander Stuijk; Gerard de Haan

    2016-01-01

    Finger-oximeters are ubiquitously used for patient monitoring in hospitals worldwide. Recently, remote measurement of arterial blood oxygenation (SpO2) with a camera has been demonstrated. Both contact and remote measurements, however, require the subject to remain static for accurate SpO2 values. This is due to the use of the common ratio-of-ratios measurement principle that measures the relative pulsatility at different wavelengths. Since the amplitudes are small, they are easily corrupted ...

  6. Highly acid-durable carbon coated Co3O4 nanoarrays as efficient oxygen evolution electrocatalysts

    KAUST Repository

    Yang, Xiulin; Li, Henan; Lu, Ang-Yu; Min, Shixiong; Idriss, Zacharie; Hedhili, Mohamed N.; Huang, Kuo-Wei; Idriss, Hicham; Li, Lain-Jong

    2016-01-01

    Most oxygen evolution reaction (OER) electrocatalysts are not stable in corrosive acids. Even the expensive RuO2 or IrO2, the most acid-resistant oxides, can be dissolved at an oxidative potential. Herein, we realize that the failures of OER catalysts are mostly caused by the weak interface between catalysts and the substrates. Hence, the study of the interface structure between catalysts and substrates is critical. In this work, we observe that the cheap OER catalysts Co3O4 can be more durable than the state-of-the-art RuO2 if the interface quality is good enough. The Co3O4 nanosheets deposited on carbon paper (Co3O4/CP) is prepared by electroplating of Co-species and followed by a two-step calcination process. The 1st step occurs in vacuum in order to maintain the surface integrity of the carbon paper and converts Co-species to Co(II)O. The 2nd step is a calcination in ambient conditions which enables the complete transformation of Co(II)O to Co3O4 without degrading the mechanical strength of the Co3O4-CP interface. Equally important, an in situ formation of a layer of amorphous carbon on top of Co3O4 further enhances the OER catalyst stability. Therefore, these key advances make the Co3O4 catalyst highly active toward the OER in 0.5 M H2SO4 with a small overpotential (370 mV), to reach 10 mA/cm2. The observed long lifetime for 86.8 h at a constant current density of 100 mA/cm2, is among the best of the reported in literature so far, even longer than the state-of-art RuO2 on CP. Overall, our study provides a new insight and methodology for the construction of a high-performance and high stability OER electrocatalysts in corrosive acidic environments.

  7. Highly acid-durable carbon coated Co3O4 nanoarrays as efficient oxygen evolution electrocatalysts

    KAUST Repository

    Yang, Xiulin

    2016-04-21

    Most oxygen evolution reaction (OER) electrocatalysts are not stable in corrosive acids. Even the expensive RuO2 or IrO2, the most acid-resistant oxides, can be dissolved at an oxidative potential. Herein, we realize that the failures of OER catalysts are mostly caused by the weak interface between catalysts and the substrates. Hence, the study of the interface structure between catalysts and substrates is critical. In this work, we observe that the cheap OER catalysts Co3O4 can be more durable than the state-of-the-art RuO2 if the interface quality is good enough. The Co3O4 nanosheets deposited on carbon paper (Co3O4/CP) is prepared by electroplating of Co-species and followed by a two-step calcination process. The 1st step occurs in vacuum in order to maintain the surface integrity of the carbon paper and converts Co-species to Co(II)O. The 2nd step is a calcination in ambient conditions which enables the complete transformation of Co(II)O to Co3O4 without degrading the mechanical strength of the Co3O4-CP interface. Equally important, an in situ formation of a layer of amorphous carbon on top of Co3O4 further enhances the OER catalyst stability. Therefore, these key advances make the Co3O4 catalyst highly active toward the OER in 0.5 M H2SO4 with a small overpotential (370 mV), to reach 10 mA/cm2. The observed long lifetime for 86.8 h at a constant current density of 100 mA/cm2, is among the best of the reported in literature so far, even longer than the state-of-art RuO2 on CP. Overall, our study provides a new insight and methodology for the construction of a high-performance and high stability OER electrocatalysts in corrosive acidic environments.

  8. Effect of hyperbaric oxygen therapy on whole blood cyanide concentrations in carbon monoxide intoxicated patients from fire accidents

    DEFF Research Database (Denmark)

    Lawson-Smith, Pia; Jansen, Erik C; Hilsted, Linda

    2010-01-01

    Hydrogen cyanide (HCN) and carbon monoxide (CO) may be important components of smoke from fire accidents. Accordingly, patients admitted to hospital from fire accidents may have been exposed to both HCN and CO. Cyanide (CN) intoxication results in cytotoxic hypoxia leading to organ dysfunction...... and possibly death. While several reports support the use of hyperbaric oxygen therapy (HBO) for the treatment of severe CO poisoning, limited data exist on the effect of HBO during CN poisoning. HBO increases the elimination rate of CO haemoglobin in proportion to the increased oxygen partial pressure...

  9. Apneic oxygenation combined with extracorporeal arteriovenous carbon dioxide removal provides sufficient gas exchange in experimental lung injury

    DEFF Research Database (Denmark)

    Nielsen, Niels Dalsgaard; Kjærgaard, Benedict; Nielsen, Jakob Koefoed

    In this porcine lung injury model, apneic oxygenation with arteriovenous CO2 removal provided sufficient gas exchange and stable hemodynamics, indicating that the method might have a potential in the treatment of severe ARDS.   Acknowledgements The membrane lungs were kindly provided by Novalung GmbH, Germany.......Background and aim of study We hypothesized that continuous high airway pressure without ventilatory movements (apneic oxygenation), using an open lung approach, combined with extracorporeal, pumpless, arterio-venous, carbon dioxide (CO2) removal would provide adequate gas exchange in acute lung...

  10. Quantitative Analysis of Oxygen Gas Exhausted from Anode through In Situ Measurement during Electrolytic Reduction

    Directory of Open Access Journals (Sweden)

    Eun-Young Choi

    2017-01-01

    Full Text Available Quantitative analysis by in situ measurement of oxygen gas evolved from an anode was employed to monitor the progress of electrolytic reduction of simulated oxide fuel in a molten Li2O–LiCl salt. The electrolytic reduction of 0.6 kg of simulated oxide fuel was performed in 5 kg of 1.5 wt.% Li2O–LiCl molten salt at 650°C. Porous cylindrical pellets of simulated oxide fuel were used as the cathode by loading a stainless steel wire mesh cathode basket. A platinum plate was employed as the anode. The oxygen gas evolved from the anode was exhausted to the instrumentation for in situ measurement during electrolytic reduction. The instrumentation consisted of a mass flow controller, pump, wet gas meter, and oxygen gas sensor. The oxygen gas was successfully measured using the instrumentation in real time. The measured volume of the oxygen gas was comparable to the theoretically calculated volume generated by the charge applied to the simulated oxide fuel.

  11. Flexible Sheet-Type Sensor for Noninvasive Measurement of Cellular Oxygen Metabolism on a Culture Dish.

    Directory of Open Access Journals (Sweden)

    Mari Kojima

    Full Text Available A novel flexible sensor was developed for the noninvasive oxygen metabolism measurement of cultivated cells and tissues. This device is composed of a transparent double-layered polymer sheet of ethylene-vinyl alcohol (EVOH and poly(dimethylsiloxane (PDMS having an array of microhole structures of 90 μm diameter and 50 μm depth on its surface. All the microhole structures were equipped with a 1-μm-thick optical chemical sensing layer of platinum porphyrin-fluoropolymer on their bottom. The three-dimensional microstructures of the sensor were fabricated by a newly developed simple and low-cost production method named self-aligned hot embossing. The device was designed to be attached slightly above the cells cultivated on a dish to form a temporarily closed microspace over the target cells during measurement. Since the change in oxygen concentration is relatively fast in the microcompartmentalized culture medium, a rapid evaluation of the oxygen consumption rate is possible by measuring the phosphorescence lifetime of the platinum porphyrin-fluoropolymer. The combined use of the device and an automated optical measurement system enabled the high-throughput sensing of cellular oxygen consumption (100 points/min. We monitored the oxygen metabolism of the human breast cancer cell line MCF7 on a Petri dish and evaluated the oxygen consumption rate to be 0.72 ± 0.12 fmol/min/cell. Furthermore, to demonstrate the utility of the developed sensing system, we demonstrated the mapping of the oxygen consumption rate of rat brain slices and succeeded in visualizing a clear difference among the layer structures of the hippocampus, i.e., the cornu ammonis (CA1 and CA3 and dentate gyrus (DG.

  12. Spatial and temporal oxygen distribution measured with oxygen microsensors in growing media with different levels of compaction

    DEFF Research Database (Denmark)

    Dresbøll, Dorte; Thorup-Kristensen, Kristian

    2011-01-01

    % compacted, respectively). The water distribution in the pot was determined as water content (gcm-3) in the top, middle and bottom layers of the peat. Oxygen content was also determined after a standard subirrigation cycle and after excessive irrigation where the bottom of the pots were left waterlogged...... for 24 h. Measurements were carried out at 5.5 weeks during the production phase and at 12 weeks at the end of the production. The results showed that with increasing compaction and density, more water was transported to the upper layers of the pot. After a standard irrigation cycle there was no effect...... in growing media and how this was affected by the physical characteristics of the growing media....

  13. Development of micro-coulometry for measuring oxygen content in copper oxides

    International Nuclear Information System (INIS)

    Sato, Fumiaki; Fujihara, Masaaki; Kambe, Shiro; Ishii, Osamu

    2006-01-01

    A micro-coulometry system was newly developed and employed for measuring the oxygen content in copper oxides using a reduced amount of material. To achieve this reduction in sample size, Ar flow rate, and coulometric current were optimized. When using 5.0 mg of YBa 2 Cu 3 O 6.71 , which is about 1/10 the amount used in conventional coulometry, the oxygen content was successfully determined to be 6.68 ± 0.03, Ar flow rate, and coulometric current were 0.1 l/min, and 1.0 mA, respectively. It was found to be necessary to continue to pass Ar through the solution before coulometry more than ten minutes and during the coulometric measurement. This method will be useful for measuring the oxygen content of oxide samples smaller than 10 mg, i.e. oxide materials produced in small quantities for electronic applications

  14. Game Changing Development Program - Next Generation Life Support Project: Oxygen Recovery From Carbon Dioxide Using Ion Exchange Membrane Electrolysis Technology

    Science.gov (United States)

    Burke, Kenneth A.; Jiao, Feng

    2016-01-01

    This report summarizes the Phase I research and development work performed during the March 13, 2015 to July 13, 2016 period. The proposal for this work was submitted in response to NASA Research Announcement NNH14ZOA001N, "Space Technology Research, Development, Demonstration, and Infusion 2014 (SpaceTech-REDDI-2014)," Appendix 14GCD-C2 "Game Changing Development Program, Advanced Oxygen Recovery for Spacecraft Life Support Systems Appendix" The Task Agreement for this Phase I work is Document Control Number: GCDP-02-TA-15015. The objective of the Phase I project was to demonstrate in laboratories two Engineering Development Units (EDU) that perform critical functions of the low temperature carbon dioxide electrolysis and the catalytic conversion of carbon monoxide into carbon and carbon dioxide. The low temperature carbon dioxide electrolysis EDU was built by the University of Delaware with Dr. Feng Jiao as the principal investigator in charge of this EDU development (under NASA Contract NNC15CA04C). The carbon monoxide catalytic conversion EDU was built by the NASA Glenn Research Center with Kenneth Burke as the principal investigator and overall project leader for the development of both EDUs. Both EDUs were successfully developed and demonstrated the critical functions for each process. The carbon dioxide electrolysis EDU was delivered to the NASA Johnson Space Center and the carbon monoxide catalytic conversion EDU was delivered to the NASA Marshall Spaceflight Center.

  15. Measuring Urban Carbon Footprint from Carbon Flows in the Global Supply Chain.

    Science.gov (United States)

    Hu, Yuanchao; Lin, Jianyi; Cui, Shenghui; Khanna, Nina Zheng

    2016-06-21

    A global multiregional input-output (MRIO) model was built for eight Chinese cities to track their carbon flows. For in-depth understanding of urban carbon footprint from the perspectives of production, consumption, and trade balance, four kinds of footprints and four redefined measurement indicators were calculated. From the global supply chain, urban carbon inflows from Mainland China were larger than outflows, while the carbon outflows to European, principal North American countries and East Asia were much larger than inflows. With the rapid urbanization of China, Construction was the largest consumer and Utilities was the largest producer. Cities with higher consumption (such as Dalian, Tianjin, Shanghai, and Beijing) should change their consumption patterns, while cities with lower production efficiency (such as Dalian, Shanghai, Ningbo, and Chongqing) should improve their technology. The cities of net carbon consumption tended to transfer carbon emissions out of them by trading in carbon-intensive products, while the cities of net carbon production tended to produce carbon-intensive products for nonlocal consumers. Our results indicated that urban carbon abatement requires not only rational consumption and industrial symbiosis at the city level, but also tighter collaboration along all stages of the global supply chain.

  16. Use of O2 airglow for calibrating direct atomic oxygen measurements from sounding rockets

    Directory of Open Access Journals (Sweden)

    G. Witt

    2009-12-01

    Full Text Available Accurate knowledge about the distribution of atomic oxygen is crucial for many studies of the mesosphere and lower thermosphere. Direct measurements of atomic oxygen by the resonance fluorescence technique at 130 nm have been made from many sounding rocket payloads in the past. This measurement technique yields atomic oxygen profiles with good sensitivity and altitude resolution. However, accuracy is a problem as calibration and aerodynamics make the quantitative analysis challenging. Most often, accuracies better than a factor 2 are not to be expected from direct atomic oxygen measurements. As an example, we present results from the NLTE (Non Local Thermodynamic Equilibrium sounding rocket campaign at Esrange, Sweden, in 1998, with simultaneous O2 airglow and O resonance fluorescence measurements. O number densities are found to be consistent with the nightglow analysis, but only within the uncertainty limits of the resonance fluorescence technique. Based on these results, we here describe how better atomic oxygen number densities can be obtained by calibrating direct techniques with complementary airglow photometer measurements and detailed aerodynamic analysis. Night-time direct O measurements can be complemented by photometric detection of the O2 (b1∑g+−X3∑g- Atmospheric Band at 762 nm, while during daytime the O2 (a1Δg−X3∑g- Infrared Atmospheric Band at 1.27 μm can be used. The combination of a photometer and a rather simple resonance fluorescence probe can provide atomic oxygen profiles with both good accuracy and good height resolution.

  17. Structural and compositional characterization of X-cut LiNbO3 crystals implanted with high energy oxygen and carbon ions

    International Nuclear Information System (INIS)

    Bentini, G.G.; Bianconi, M.; Cerutti, A.; Chiarini, M.; Pennestri, G.; Sada, C.; Argiolas, N.; Bazzan, M.; Mazzoldi, P.; Guzzi, R.

    2005-01-01

    High energy implantation of medium-light elements such as oxygen and carbon was performed in X-cut LiNbO 3 single crystals in order to prepare high quality optical waveguides. The compositional and damage profiles, obtained by exploiting the secondary ion mass spectrometry and Rutherford back-scattering techniques respectively, were correlated to the structural properties measured by the high resolution X-ray diffraction. This study evidences the development of tensile strain induced by the ion implantation that can contribute to the decrease of the ordinary refractive index variation through the photo-elastic effect

  18. Effect of carbogen on tumor oxygenation: combined fluorine-19 and proton MRI measurements

    International Nuclear Information System (INIS)

    Fan Xiaobing; River, Jonathan N.; Zamora, Marta; Al-Hallaq, Hania A.; Karczmar, Gregory S.

    2002-01-01

    Purpose: Blood oxygen level dependent (BOLD) contrast in magnetic resonance imaging (MRI) has been widely used for noninvasive evaluation of the effects of tumor-oxygenating agents. However, there have been few tests of the validity of this method. The goal of the present work was to use the T 1 of fluorine-19 in perfluorocarbon (PFC) emulsions as a 'gold standard' for comparison with BOLD MRI. Methods and Materials: Rats bearing R3230AC tumors implanted in the hind limb were injected with an emulsion of perfluoro-15-crown-5-ether for 2-3 days before experiments, which ensured that the PFC emulsion concentrated in the tumors. We correlated changes in tumor oxygenation caused by carbogen inhalation measured by 1 H BOLD MRI with quantitative 19 F measurements. The 19 F spin-lattice relaxation rate R 1 (= 1/T 1 ) was measured to determine initial oxygen tension (pO 2 ) in each image pixel containing the PFC, and changes in pO 2 during carbogen (95% O 2 , 5% CO 2 ) breathing. In a second carbogen breathing period, changes in water signal linewidth were measured using high spectral and spatial resolution imaging. 19 F and 1 H measurements were used to classify pixels as responders to carbogen (pixels where oxygen increased significantly) or nonresponders (no significant change in tumor oxygenation). Results: The 19 F and 1 H measurements agreed in 65% ± 11% of pixels (n = 14). Agreement was even stronger among pixels where 1 H showed increased oxygenation; 19 F measurements agreed with 1 H measurements in over 79% ± 11% of these pixels. Similarly, there was strong agreement between the two modalities in pixels where 19 F reported no change in pO 2 ; 1 H also showed no changes in 76% ± 18% of these pixels. Quantitative correlation of changes T 2 * (ΔT 2 *) in 1 H and changes R 1 (ΔR 1 ) in 19 F was weak during carbogen breathing, and averaged over the whole tumor was ∼0.40 for 14 experiments. However, the spatial patterns of 1 H and 19 F changes were qualitatively

  19. Retinal hemodynamic oxygen reactivity assessed by perfusion velocity, blood oximetry and vessel diameter measurements

    DEFF Research Database (Denmark)

    Klefter, Oliver Niels; Lauritsen, Anne Øberg; Larsen, Michael

    2015-01-01

    PURPOSE: To test the oxygen reactivity of a fundus photographic method of measuring macular perfusion velocity and to integrate macular perfusion velocities with measurements of retinal vessel diameters and blood oxygen saturation. METHODS: Sixteen eyes in 16 healthy volunteers were studied at two...... is a valid method for assessing macular perfusion. Results were consistent with previous observations of hyperoxic blood flow reduction using blue field entoptic and laser Doppler velocimetry. Retinal perfusion seemed to be regulated around individual set points according to blood glucose levels. Multimodal...

  20. Measuring reactive oxygen and nitrogen species with fluorescent probes: challenges and limitations

    Science.gov (United States)

    Kalyanaraman, Balaraman; Darley-Usmar, Victor; Davies, Kelvin J.A.; Dennery, Phyllis A.; Forman, Henry Jay; Grisham, Matthew B.; Mann, Giovanni E.; Moore, Kevin; Roberts, L. Jackson; Ischiropoulos, Harry

    2013-01-01

    The purpose of this position paper is to present a critical analysis of the challenges and limitations of the most widely used fluorescent probes for detecting and measuring reactive oxygen and nitrogen species. Where feasible, we have made recommendations for the use of alternate probes and appropriate analytical techniques that measure the specific products formed from the reactions between fluorescent probes and reactive oxygen and nitrogen species. We have proposed guidelines that will help present and future researchers with regard to the optimal use of selected fluorescent probes and interpretation of results. PMID:22027063

  1. Carbon Nanotubes’ Effect on Mitochondrial Oxygen Flux Dynamics: Polarography Experimental Study and Machine Learning Models using Star Graph Trace Invariants of Raman Spectra

    Directory of Open Access Journals (Sweden)

    Michael González-Durruthy

    2017-11-01

    Full Text Available This study presents the impact of carbon nanotubes (CNTs on mitochondrial oxygen mass flux (Jm under three experimental conditions. New experimental results and a new methodology are reported for the first time and they are based on CNT Raman spectra star graph transform (spectral moments and perturbation theory. The experimental measures of Jm showed that no tested CNT family can inhibit the oxygen consumption profiles of mitochondria. The best model for the prediction of Jm for other CNTs was provided by random forest using eight features, obtaining test R-squared (R2 of 0.863 and test root-mean-square error (RMSE of 0.0461. The results demonstrate the capability of encoding CNT information into spectral moments of the Raman star graphs (SG transform with a potential applicability as predictive tools in nanotechnology and material risk assessments.

  2. Accretion onto Carbon-Oxygen White Dwarfs as a possible mechanism for growth to the Chandrasekhar Limit

    Science.gov (United States)

    Starrfield, Sumner; Bose, Maitrayee; Iliadis, Christian; Hix, William R.; José, Jordi; Hernanz, Margarita

    2017-08-01

    We have continued our studies of accretion onto white dwarfs by following the evolution of thermonuclear runaways (TNRs) on Carbon Oxygen (CO) white dwarfs. We have varied the mass of the white dwarf and the composition of the accreted material. We use the results of the multi-dimensional studies of TNRs in white dwarfs, accreting only Solar matter, which show that sufficient core material is dredged-up by the TNR and then ejected by the explosion to agree with the observations of the ejecta abundances. We have also found that the initial 12C abundance is inversely proportional to the amount of material accreted prior to the TNR. Therefore, we first accrete Solar material and follow the evolution until a TNR occurs. Because the 12C abundance is significantly smaller then if we had initially mixed the accreting gas with the carbon-oxygen core, more matter takes part in the explosion than if we had begun the evolution with the mixed composition. We then instantaneously switch the composition to a mixture with either 25% core material or 50% core material (plus accreted material) and follow the resulting evolution of the TNR. We use our 1D, Lagrangian, hydrodynamic code: NOVA. We report on the results of these new simulations and compare the ejecta abundances to those measured in pre-solar grains that are thought to arise from classical nova explosions. These results will also be compared to recent results with SHIVA (Josè and Hernanz). We find that there are some white dwarf masses where significantly less mass is ejected than accreted during the Classical Nova event and, therefore, the white dwarf is growing in mass as a result of the accretion and in spite of the resulting explosion.This work was supported in part by NASA under the Astrophysics Theory Program grant 14-ATP14-0007 and the U.S. DOE under Contract No. DE-FG02- 97ER41041. SS acknowledges partial support from NASA, NSF, and HST grants to ASU and WRH is supported by the U.S. Department of Energy, Office

  3. Inflammability of magnesium and its alloys in carbon dioxide either pure or mixed with water vapour, air or oxygen

    International Nuclear Information System (INIS)

    Baque, P.; Chevilliard, C.; Darras, R.

    1964-01-01

    Whereas low contents of metallic additions have only a small influence on the temperature at which magnesium begins to burn in carbon dioxide, an increase in the specific surface area of the samples is likely to reduce it considerably, the self-heating phenomena being then more pronounced. On the other hand, the exact nature of the surrounding atmosphere is a very important factor; thus the temperature at which ignition begins increases with increasing carbon dioxide pressure, decreases very rapidly when the moisture content of this gas increases up to 3000 v.p.m., and decreases regularly when the partial pressure of air or oxygen increases. (authors) [fr

  4. Measurement of carbon fixation and allocation using 11C-labeled carbon dioxide

    International Nuclear Information System (INIS)

    Strain, B.R.; Goeschl, J.D.; Jaeger, C.H.; Fares, Y.; Magnuson, C.E.; Nelson, C.E.

    1983-01-01

    This paper describes the use of continuously produced and applied 11 C in measurements of carbon dioxide assimilation and C movement in plant research. This technique differs from the pulsing type 11 C research underway in other laboratories by being continuous and on-line with computer analysis making steady-state measurements of carbon fixation and movement possible. The studies to be described here make clear the advantages of using continuously produced and applied short half-lived isotopes

  5. Influence of oxygen, nitrogen and carbonic gas during gamma irradiation of 'Sitophilus zeamais' Mots. and 'Zabrotes subfasciatus' (Boh.)

    International Nuclear Information System (INIS)

    Wiendl, F.M.; Tornisielo, V.L.; Walder, J.M.N.; Sgrillo, R.B.

    1976-01-01

    Zero to twenty-four hour old adults of the corn-weevil (S. zeamais) and of the bean weevil (Z. subfasciatus) with their food were irradiated with 5 krad of gamma rays from a Co-60 source (dose rate of 96.25 krad/h). The foodstuffs for the corn weevil were maize and rice as well as common beans for the bean weevil. Before irradiation, the insects of each treatment were exposed to 30 minutes gas fluxes of air, oxygen, nitrogen or carbonic gas, respectively. After irradiation, insects were kept in a temperature controlled chamber at 28 0 C. Losses in weight of the foodstuffs were recorded for 51 weeks. The greatest weight loss was found in the treatment with air flux. Weight losses decreased with the nitrogen, carbonic gas and oxygen treatments, respectively [pt

  6. De-oxygenation of CO2 by using Hydrogen, Carbon and Methane over Alumina-Supported Catalysts

    Directory of Open Access Journals (Sweden)

    R.Y. Raskar

    2012-06-01

    Full Text Available The de-oxygenation of CO2 was explored by using hydrogen, methane, carbon etc., over alumina supported catalysts. The alumina-supported ruthenium, rhodium, platinum, molybdenum, vanadium and magnesium catalysts were first reduced in hydrogen atmosphere and then used for the de-oxygenation of CO2. Furthermore, experimental variables for the de-oxygenation of CO2 were temperature (range 50 to 650 oC, H2/CO2 mole ratios (1.0 to 5, and catalyst loading (0.5 to 10 wt %. During the de-oxygenation of CO2 with H2 or CH4 or carbon, conversion of CO2, selectivity to CO and CH4 were estimated. Moreover, 25.4 % conversion of CO2 by hydrogen was observed over 1 wt% Pt/Al2O3 catalyst at 650 oC with 33.8 % selectivity to CH4. However, 8.1 to 13.9 % conversion of CO2 was observed over 1 wt% Pt/Al2O3 catalyst at 550 oC in the presence of both H2 and CH4. Moreover, 42.8 to 79.4 % CH4 was converted with 9 to 23.1 % selectivity to CO. It was observed that the de-oxygenation of CO2 by hydrogen, carbon and methane produced carbon, CO and CH4. © 2012 BCREC UNDIP. All rights reservedReceived: 6th February 2012; Revised: 23rd April 2012; Accepted: 24th April 2012[How to Cite: R. Y. Raskar, K. B. Kale, A. G. Gaikwad. (2011. De-oxygenation of CO2 by using Hydrogen, Carbon and Methane over Alumina-Supported Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 59-69.  doi:10.9767/bcrec.7.1.1631.59-69][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1631.59-69 ] | View in 

  7. A technique for measuring oxygen saturation in biological tissues based on diffuse optical spectroscopy

    Science.gov (United States)

    Kleshnin, Mikhail; Orlova, Anna; Kirillin, Mikhail; Golubiatnikov, German; Turchin, Ilya

    2017-07-01

    A new approach to optical measuring blood oxygen saturation was developed and implemented. This technique is based on an original three-stage algorithm for reconstructing the relative concentration of biological chromophores (hemoglobin, water, lipids) from the measured spectra of diffusely scattered light at different distances from the probing radiation source. The numerical experiments and approbation of the proposed technique on a biological phantom have shown the high reconstruction accuracy and the possibility of correct calculation of hemoglobin oxygenation in the presence of additive noise and calibration errors. The obtained results of animal studies have agreed with the previously published results of other research groups and demonstrated the possibility to apply the developed technique to monitor oxygen saturation in tumor tissue.

  8. Surface modification of carbon/epoxy prepreg using oxygen plasma and its effect on the delamination resistance behavior of carbon/epoxy composites

    International Nuclear Information System (INIS)

    Kim, M.H.; Rhee, K.Y.; Kim, H.J.; Jung, D.H.

    2007-01-01

    It was shown in previous study that the fracture toughness of carbon/epoxy laminated composites could be significantly improved by modifying the surface of the prepreg using Ar + irradiation in an oxygen environment. In this study, the surface of carbon/epoxy prepreg was modified using an oxygen plasma to improve the delamination resistance behavior of carbon/epoxy laminated composites. The variation of the contact angle on the prepreg surface was determined as a function of the modification time, in order to determine the optimal modification time. An XPS analysis was conducted to investigate the chemical changes on the surface of the prepreg caused by the plasma modification. Mode I delamination resistance curves of the composites with and without surface modification were plotted as a function of the delamination increment. The results showed that the contact angle varied from ∼64 o to ∼47 o depending on the modification time and reached a minimum for a modification time of 30 min. The XPS analysis showed that the hydrophilic carbonyl C=O group was formed by the oxygen plasma modification. The results also showed that the delamination resistance behavior was significantly improved by the plasma modification of the prepreg. This improvement was caused by the better layer-to-layer adhesion as well as increased interfacial strength between the fibers and matrix

  9. Durability of carbon-supported manganese oxide nanoparticles for the oxygen reduction reaction (ORR) in alkaline medium

    Czech Academy of Sciences Publication Activity Database

    Roche, I.; Chainet, E.; Chatenet, M.; Vondrák, Jiří

    2008-01-01

    Roč. 38, č. 9 (2008), s. 1195-1201 ISSN 0021-891X R&D Projects: GA AV ČR KJB4813302; GA ČR GA104/02/0731 Grant - others:CNRS(FR) 18105 Institutional research plan: CEZ:AV0Z40320502 Keywords : oxygen reduction reaction * rotating ring-disc electrode * carbon-supported manganese oxide Subject RIV: CA - Inorganic Chemistry Impact factor: 1.540, year: 2008

  10. Measuring oxygen yields of a thermal conversion/elemental analyzer-isotope ratio mass spectrometer for organic and inorganic materials through injection of CO.

    Science.gov (United States)

    Yin, Xijie; Chen, Zhigang

    2014-12-01

    The thermal conversion/elemental analyzer-isotope ratio mass spectrometer (TC/EA-IRMS) is widely used to measure the δ(18) O value of various substances. A premise for accurate δ(18) O measurement is that the oxygen in the sample can be converted into carbon monoxide (CO) quantitatively or at least proportionally. Therefore, a precise method to determine the oxygen yield of TC/EA-IRMS measurements is needed. Most studies have used the CO peak area obtained from a known amount of a solid reference material (for example, benzoic acid) to calibrate the oxygen yield of the sample. Although it was assumed that the oxygen yield of the solid reference material is 100%, no direct evidence has been provided. As CO is the analyte gas for δ(18) O measurement by IRMS, in this study, we use a six-port valve to inject CO gas into the TC/EA. The CO is carried to the IRMS by the He carrier gas and the CO peak area is measured by the IRMS. The CO peak area thus obtained from a known amount of the injected CO is used to calibrate the oxygen yield of the sample. The oxygen yields of commonly used organic and inorganic reference materials such as benzoic acid (C6 H5 COOH), silver phosphate (Ag3 PO4 ), calcium carbonate (CaCO3 ) and silicon dioxide (SiO2 ) are investigated at different reactor temperatures and sample sizes. We obtained excellent linear correlation between the peak area for the injected CO and its oxygen atom amount. C6 H5 COOH has the highest oxygen yield, followed by Ag3 PO4 , CaCO3 and SiO2 . The oxygen yields of TC/EA-IRMS are less than 100% for both organic and inorganic substances, but the yields are relatively stable at the specified reactor temperature and for a given quantity of sample. Copyright © 2014 John Wiley & Sons, Ltd.

  11. Stable isotope ratio measurements in hydrogen, nitrogen, and oxygen using Raman scattering

    International Nuclear Information System (INIS)

    Harney, R.C.; Bloom, S.D.; Milanovich, F.P.

    1975-01-01

    A method for measuring stable isotope ratios using laser Raman scattering was developed which may prove of significant utility and benefit in stable isotope tracer studies. Crude isotope ratio measurements obtained with a low-power laser indicate that with current technology it should be possible to construct an isotope ratio measurement system using laser Raman scattering that is capable of performing 0.1 percent accuracy isotope ratio measurements of 16 O/ 18 O in natural abundance oxygen gas or 14 N/ 15 N in natural abundance nitrogen gas in times less than two minutes per sample. Theory pertinent to the technique, designs of specific isotope ratio spectrometer systems, and data relating to isotope ratio measurements in hydrogen, nitrogen, and oxygen are presented. In addition, the current status of several studies utilizing this technique is discussed. (auth)

  12. Self-assembled dopamine nanolayers wrapped carbon nanotubes as carbon-carbon bi-functional nanocatalyst for highly efficient oxygen reduction reaction and antiviral drug monitoring

    Science.gov (United States)

    Khalafallah, Diab; Akhtar, Naeem; Alothman, Othman Y.; Fouad, H.; Abdelrazek khalil, Khalil

    2017-09-01

    Oxygen reduction reaction (ORR) catalysts are the heart of eco-friendly energy resources particularly low temperature fuel cells. Although valuable efforts have been devoted to synthesize high performance catalysts for ORR, considerable challenges are extremely desirable in the development of energy technologies. Herein, we report a simple self-polymerization method to build a thin film of dopamine along the tubular nanostructures of multi-walled carbon nanotubes (CNT) in a weak alkaline solution. The dopamine@CNT hybrid (denoted as DA@CNT) reveals an enhanced electrocatalytic activity towards ORR with highly positive onset potential and cathodic current as a result of their outstanding features of longitudinal mesoporous structure, high surface area, and ornamentation of DA layers with nitrogen moieties, which enable fast electron transport and fully exposed electroactive sites. Impressively, the as-obtained hybrid afford remarkable electrochemical durability for prolonged test time of 60,000 s compared to benchmark Pt/C (20 wt%) catalyst. Furthermore, the developed DA@CNT electrode was successfully applied to access the quality of antiviral drug named Valacyclovir (VCR). The DA@CNT electrode shows enhanced sensing performance in terms of large linear range (3-75 nM), low limit of detection (2.55 nM) than CNT based electrode, indicating the effectiveness of the DA coating. Interestingly, the synergetic effect of nanostructured DA and CNT can significantly boost the electronic configuration and exposure level of active species for ORR and biomolecule recognition. Therefore, the existing carbon-based porous electrocatalyst may find numerous translational applications as attractive alternative to noble metals in polymer electrolyte membrane fuel cells and quality control assessment of pharmaceutical and therapeutic drugs.

  13. Simultaneous Blood–Tissue Exchange of Oxygen, Carbon Dioxide, Bicarbonate, and Hydrogen Ion

    Science.gov (United States)

    Dash, Ranjan K.; Bassingthwaighte, James B.

    2014-01-01

    A detailed nonlinear four-region (red blood cell, plasma, interstitial fluid, and parenchymal cell) axially distributed convection-diffusion-permeation-reaction-binding computational model is developed to study the simultaneous transport and exchange of oxygen (O2) and carbon dioxide (CO2) in the blood–tissue exchange system of the heart. Since the pH variation in blood and tissue influences the transport and exchange of O2 and CO2 (Bohr and Haldane effects), and since most CO2 is transported as HCO3- (bicarbonate) via the CO2 hydration (buffering) reaction, the transport and exchange of HCO3- and H+ are also simulated along with that of O2 and CO2. Furthermore, the model accounts for the competitive nonlinear binding of O2 and CO2 with the hemoglobin inside the red blood cells (nonlinear O2–CO2 interactions, Bohr and Haldane effects), and myoglobin-facilitated transport of O2 inside the parenchymal cells. The consumption of O2 through cytochrome-c oxidase reaction inside the parenchymal cells is based on Michaelis–Menten kinetics. The corresponding production of CO2 is determined by respiratory quotient (RQ), depending on the relative consumption of carbohydrate, protein, and fat. The model gives a physiologically realistic description of O2 transport and metabolism in the microcirculation of the heart. Furthermore, because model solutions for tracer transients and steady states can be computed highly efficiently, this model may be the preferred vehicle for routine data analysis where repetitive solutions and parameter optimization are required, as is the case in PET imaging for estimating myocardial O2 consumption. PMID:16775761

  14. Quantitative measurement of carbon nanotubes released from their composites using thermal carbon analysis

    International Nuclear Information System (INIS)

    Ogura, I; Honda, K; Shigeta, M; Kotake, M; Uejima, M

    2015-01-01

    The ability of thermal carbon analysis to determine CNTs was evaluated in the presence of a polymer (Polystyrene, PS). Samples placed in an Au (Pt) foil boat were measured using a thermal-carbon analyzer, and the results were compared with gravimetric measurements of sample masses obtained using an ultra-microbalance. First, debris from the polymer without CNTs (i.e., PS debris) was analyzed. The amount of PS debris detected in the organic carbon (OC) fraction was found to be in good agreement with the gravimetrically measured mass of the PS debris, while the amount of pyrolyticallygenerated carbon soot detected in the elemental carbon (EC) fraction was negligible. Next, single-wall CNT (AIST/TASC Super-Growth) powder was analyzed, and the amount of the CNT powder detected in the EC fraction was found to be 95-96% of the gravimetrically measured mass of the CNT powder. Subsequently, a mixture of the PS debris and the CNT powder was analyzed, and the amounts of detected OC and EC were found to be comparable to the gravimetrically measured masses of the PS debris and the CNT powder, respectively. Finally, debris from 5 wt% CNT-PS composites was analyzed, and amounts of OC and EC detected were found to be approximately comparable to the estimated masses of the PS and the CNTs in the debris of CNT-PS composite, respectively. The results therefore indicate thermal carbon analysis is capable of determining CNTs in the presence of PS. (paper)

  15. Feasibility studies of a carbon/oxygen logging tool for evaluating the CO2 content of the medium in nuclear device containment

    International Nuclear Information System (INIS)

    West, H.I. Jr.; Glasgow, J.E.

    1983-12-01

    The feasibility of using oil-well bore-hole logging techniques for assaying the carbonate content of a potential shot site has been investigated. The procedure makes use of the detection of the 4439-keV γ ray of carbon and the 6130-keV γ ray of oxygen produced by the inelastic scattering of 14-MeV neutrons in the bore-hole medium. For the needs of the containment program, a sensitivity of detection of CO 2 to less than or equal to 0.02 weight fraction must be achieved. Laboratory measurements indicate that only with considerable development effort could a tool be made that would come close to achieving this goal

  16. Measuring Biomass and Carbon Stock in Resprouting Woody Plants

    Science.gov (United States)

    Matula, Radim; Damborská, Lenka; Nečasová, Monika; Geršl, Milan; Šrámek, Martin

    2015-01-01

    Resprouting multi-stemmed woody plants form an important component of the woody vegetation in many ecosystems, but a clear methodology for reliable measurement of their size and quick, non-destructive estimation of their woody biomass and carbon stock is lacking. Our goal was to find a minimum number of sprouts, i.e., the most easily obtainable, and sprout parameters that should be measured for accurate sprout biomass and carbon stock estimates. Using data for 5 common temperate woody species, we modelled carbon stock and sprout biomass as a function of an increasing number of sprouts in an interaction with different sprout parameters. The mean basal diameter of only two to five of the thickest sprouts and the basal diameter and DBH of the thickest sprouts per stump proved to be accurate estimators for the total sprout biomass of the individual resprouters and the populations of resprouters, respectively. Carbon stock estimates were strongly correlated with biomass estimates, but relative carbon content varied among species. Our study demonstrated that the size of the resprouters can be easily measured, and their biomass and carbon stock estimated; therefore, resprouters can be simply incorporated into studies of woody vegetation. PMID:25719601

  17. Selection criteria for oxidation method in total organic carbon measurement.

    Science.gov (United States)

    Yoon, GeunSeok; Park, Sang-Min; Yang, Heuiwon; Tsang, Daniel C W; Alessi, Daniel S; Baek, Kitae

    2018-05-01

    During the measurement of total organic carbon (TOC), dissolved organic carbon is converted into CO 2 by using high temperature combustion (HTC) or wet chemical oxidation (WCO). However, the criteria for selecting the oxidation methods are not clear. In this study, the chemical structures of organic material were considered as a key factor to select the oxidation method used. Most non-degradable organic compounds showed a similar oxidation efficiency in both methods, including natural organic compounds, dyes, and pharmaceuticals, and thus both methods are appropriate to measure TOC in waters containing these compounds. However, only a fraction of the carbon in the halogenated compounds (perfluorooctanoic acid and trifluoroacetic acid) were oxidized using WCO, resulting in measured TOC values that are considerably lower than those determined by HTC. This result is likely due to the electronegativity of halogen elements which inhibits the approach of electron-rich sulfate radicals in the WCO, and the higher bond strength of carbon-halogen pairs as compared to carbon-hydrogen bonds, which results in a lower degree of oxidation of the compounds. Our results indicate that WCO could be used to oxidize most organic compounds, but may not be appropriate to quantify TOC in organic carbon pools that contain certain halogenated compounds. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Three-dimensional iron, nitrogen-doped carbon foams as efficient electrocatalysts for oxygen reduction reaction in alkaline solution

    International Nuclear Information System (INIS)

    Ma, Yanjiao; Wang, Hui; Feng, Hanqing; Ji, Shan; Mao, Xuefeng; Wang, Rongfang

    2014-01-01

    Graphical abstract: Three-dimentional Fe, N-doped carbon foams prepared by two steps exhibited comparable catalytic activity for oxygen reduction reaction to commercial Pt/C due to the unique structure and the synergistic effect of Fe and N atoms. - Highlights: • Three-dimensional Fe, N-doped carbon foam (3D-CF) were prepared. • 3D-CF exhibits comparable catalytic activity to Pt/C for oxygen reduction reaction. • The enhanced activity of 3D-CF results of its unique structure. - Abstract: Three-dimensional (3D) Fe, N-doped carbon foams (3D-CF) as efficient cathode catalysts for the oxygen reduction reaction (ORR) in alkaline solution are reported. The 3D-CF exhibit interconnected hierarchical pore structure. In addition, Fe, N-doped carbon without porous strucuture (Fe-N-C) and 3D N-doped carbon without Fe (3D-CF’) are prepared to verify the electrocatalytic activity of 3D-CF. The electrocatalytic performance of as-prepared 3D-CF for ORR shows that the onset potential on 3D-CF electrode positively shifts about 41 mV than those of 3D-CF’ and Fe-N-C respectively. In addition, the onset potential on 3D-CF electrode for ORR is about 27 mV more negative than that on commercial Pt/C electrode. 3D-CF also show better methanol tolerance and durability than commercial Pt/C catalyst. These results show that to synthesize 3D hierarchical pores with high specific surface area is an efficient way to improve the ORR performance

  19. Microvascular and mitochondrial PO 2 simultaneously measured by oxygen-dependent delayed luminescence

    NARCIS (Netherlands)

    S.I.A. Bodmer (Sander I. A.); G. Balestra (Gianmarco); F.A. Harms (Floor A.); T. Johannes (Tanja); N.J.H. Raat (Nicolaas); R.J. Stolker (Robert); E.G. Mik (Egbert)

    2012-01-01

    textabstractMeasurement of tissue oxygenation is a complex task and various techniques have led to a wide range of tissue PO 2 values and contradictory results. Tissue is compartmentalized in microcirculation, interstitium and intracellular space and current techniques are biased towards a certain

  20. Ionic conductivity of perovskite LaCoO3 measured by oxygen permeation technique

    NARCIS (Netherlands)

    Chen, C.H.; Kruidhof, H.; Bouwmeester, Henricus J.M.; Burggraaf, Anthonie; Burggraaf, A.J.

    1997-01-01

    Oxygen permeation measurement is demonstrated, not only for a mixed oxide ionic and electronic conductor, but also as a new alternative to determine ambipolar conductivities, which can be usually reduced to be partial conductivities (either ionic or electronic). As a model system and an end member

  1. Measurement of oxygen consumption with the Cosmed K2: a comparative study

    NARCIS (Netherlands)

    Forkink, A.; Frings-Dresen, M. H.

    1994-01-01

    An instrument that accurately measures oxygen consumption (VO2) during field performance is valuable for investigations of physiological workload. Cosmed (Rome, Italy) has introduced such an instrument, the Cosmed K2. In this study the Cosmed K2 was compared with the Oxyconbeta (Jaeger, Breda, The

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

    NARCIS (Netherlands)

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

    2007-01-01

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

  3. High-performance supercapacitors of carboxylate-modified hollow carbon nanospheres coated on flexible carbon fibre paper: Effects of oxygen-containing group contents, electrolytes and operating temperature

    International Nuclear Information System (INIS)

    Phattharasupakun, Nutthaphon; Wutthiprom, Juthaporn; Suktha, Phansiri; Iamprasertkun, Pawin; Chanlek, Narong; Shepherd, Celine; Hadzifejzovic, Emina; Moloney, Mark G.; Foord, John S.; Sawangphruk, Montree

    2017-01-01

    Although functionalized carbon-based materials have been widely used as the supercapacitor electrodes, the optimum contents of the functional groups, the charge storage mechanisms, and the effects of electrolytes and operating temperature have not yet been clearly investigated. In this work, carboxylate-modified hollow carbon nanospheres (c-HCN) with different functional group contents synthesized by an oxidation process of carbon nanospheres with nitric acid were coated on flexible carbon fibre paper and used as the supercapacitor electrodes. An as-fabricated supercapacitor of the c-HCN with a finely tuned 6.2 atomic % of oxygen of the oxygen-containing groups in an ionic liquid electrolyte exhibits a specific capacitance of 390 F g"−"1, a specific energy of 115 Wh kg"−"1, and a maximum specific power of 13548 W kg"−"1 at 70 °C. The charge storage mechanism investigated is based on the chemical adsorption of the ionic liquid electrolyte on the c-HCN electrode. This process is highly reversible leading to high capacity retention. The supercapacitor in this work may be practically used in many high energy and power applications.

  4. Characterization of carbonaceous solids by oxygen chemisorption

    Energy Technology Data Exchange (ETDEWEB)

    Furimsky, E.; Palmer, A.; Duguay, D.G.; McConnell, D.G.; Henson, D.E.

    1988-06-01

    Oxygen chemisorption of high and low carbon carbonaceous solids was measured in an electro-microbalance at 200 degrees C in air. A linear correlation between the amount of chemisorbed oxygen and H/C ratio as well as aromaticity was established for the high carbon solids. For the low carbon solids a linear correlation was established between the amount of chemisorbed oxygen and the content of organic matter. Experimental observations are discussed in terms of structural aspects of the solids. Oxygen chemisorption is a suitable technique for a rapid characterization of carbonaceous solids including coal. 15 refs., 7 figs., 3 tabs.

  5. 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

  6. Magnetic susceptibility measurement of solid oxygen at pressures up to 3.3 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Mito, M., E-mail: mitoh@tobata.isc.kyutech.ac.jp; Yamaguchi, S.; Tsuruda, H.; Deguchi, H. [Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Ishizuka, M. [Renovation Center of Instruments for Science Education and Technology, Osaka University, Toyonaka 560-8531 (Japan)

    2014-01-07

    The magnetic susceptibility of solid oxygen had long been observed only in the restricted pressure region below 0.8 GPa. We succeeded in extending the pressure region up to 3.3 GPa by clamping condensed oxygen in the sample chamber of a miniature diamond anvil cell and measuring the dc magnetic susceptibility using a superconducting quantum interference device magnetometer. In this experiment, the well-known α–β and β–γ transitions are observed in the phase diagram, suggesting consistency with the previous results of X-ray and Raman studies. In addition, a new magnetic anomaly is observed in the β phase.

  7. Photoirradiation system with depth optical dosimetry control in initial oxygen saturation measurement

    International Nuclear Information System (INIS)

    Quintanar, L.; Stolik, S.; Rosa, J. de la; Moreno, E.

    2012-01-01

    Photodynamic Therapy is a technique in which a photosensitizing substance is applied that is activated by light and it generates reactive oxygen species which cause selective cell destruction. The efficiency of the therapy is affected by the parameters dose. In this work it is shown a photo-irradiation system for superficial Photodynamic Therapy, using as a light source a light emitting diode with an automatic control of optical power based on a model of the distribution of light in depth that was tested in tissue phantoms. It also has a reflective pulse oximeter for the measurement of the initial oxygen saturation. (Author)

  8. The effect of topological defects and oxygen adsorption on the electronic transport properties of single-walled carbon-nanotubes

    International Nuclear Information System (INIS)

    Grujicic, M.; Cao, G.; Singh, R.

    2003-01-01

    Ab initio density functional theory (DFT) calculations of the interactions between isolated infinitely-long semiconducting zig-zag (10, 0) or isolated infinitely-long metallic arm-chair (5, 5) single-walled carbon-nanotubes (SWCNTs) and single oxygen-molecules are carried out in order to determine the character of molecular-oxygen adsorption and its effect on electronic transport properties of these SWCNTs. A Green's function method combined with a nearest-neighbor tight-binding Hamiltonian in a non-orthogonal basis is used to compute the electrical conductance of SWCNTs and its dependence on the presence of topological defects in SWCNTs and of molecular-oxygen adsorbates. The computational results obtained show that in both semiconducting and metallic SWCNTs, oxygen-molecules are physisorbed to the defect-free nanotube walls, but when such walls contain topological defects, oxygen-molecules become strongly chemisorbed. In semiconducting (10, 0) SWCNTs, physisorbed O 2 -molecules are found to significantly increase electrical conductance while the effect of 7-5-5-7 defects is practically annulled by chemisorbed O 2 -molecules. In metallic (5, 5) SWCNTs, both O 2 adsorbates and 7-5-5-7 defects are found to have a relatively small effect on electrical conductance of these nanotubes

  9. Using measurements for evaluation of black carbon modeling

    Directory of Open Access Journals (Sweden)

    S. Gilardoni

    2011-01-01

    Full Text Available The ever increasing use of air quality and climate model assessments to underpin economic, public health, and environmental policy decisions makes effective model evaluation critical. This paper discusses the properties of black carbon and light attenuation and absorption observations that are the key to a reliable evaluation of black carbon model and compares parametric and nonparametric statistical tools for the quantification of the agreement between models and observations. Black carbon concentrations are simulated with TM5/M7 global model from July 2002 to June 2003 at four remote sites (Alert, Jungfraujoch, Mace Head, and Trinidad Head and two regional background sites (Bondville and Ispra. Equivalent black carbon (EBC concentrations are calculated using light attenuation measurements from January 2000 to December 2005. Seasonal trends in the measurements are determined by fitting sinusoidal functions and the representativeness of the period simulated by the model is verified based on the scatter of the experimental values relative to the fit curves. When the resolution of the model grid is larger than 1° × 1°, it is recommended to verify that the measurement site is representative of the grid cell. For this purpose, equivalent black carbon measurements at Alert, Bondville and Trinidad Head are compared to light absorption and elemental carbon measurements performed at different sites inside the same model grid cells. Comparison of these equivalent black carbon and elemental carbon measurements indicates that uncertainties in black carbon optical properties can compromise the comparison between model and observations. During model evaluation it is important to examine the extent to which a model is able to simulate the variability in the observations over different integration periods as this will help to identify the most appropriate timescales. The agreement between model and observation is accurately described by the overlap of

  10. Highly Efficient Electrocatalysts for Oxygen Reduction Reaction Based on 1D Ternary Doped Porous Carbons Derived from Carbon Nanotube Directed Conjugated Microporous Polymers

    KAUST Repository

    He, Yafei; Gehrig, Dominik; Zhang, Fan; Lu, Chenbao; Zhang, Chao; Cai, Ming; Wang, Yuanyuan; Laquai, Fré dé ric; Zhuang, Xiaodong; Feng, Xinliang

    2016-01-01

    © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.One-dimensional (1D) porous materials have shown great potential for gas storage and separation, sensing, energy storage, and conversion. However, the controlled approach for preparation of 1D porous materials, especially porous organic materials, still remains a great challenge due to the poor dispersibility and solution processability of the porous materials. Here, carbon nanotube (CNT) templated 1D conjugated microporous polymers (CMPs) are prepared using a layer-by-layer method. As-prepared CMPs possess high specific surface areas of up to 623 m2 g-1 and exhibit strong electronic interactions between p-type CMPs and n-type CNTs. The CMPs are used as precursors to produce heteroatom-doped 1D porous carbons through direct pyrolysis. As-produced ternary heteroatom-doped (B/N/S) 1D porous carbons possess high specific surface areas of up to 750 m2 g-1, hierarchical porous structures, and excellent electrochemical-catalytic performance for oxygen reduction reaction. Both of the diffusion-limited current density (4.4 mA cm-2) and electron transfer number (n = 3.8) for three-layered 1D porous carbons are superior to those for random 1D porous carbon. These results demonstrate that layered and core-shell type 1D CMPs and related heteroatom-doped 1D porous carbons can be rationally designed and controlled prepared for high performance energy-related applications.

  11. Synergistic effect of single-electron-trapped oxygen vacancies and carbon species on the visible light photocatalytic activity of carbon-modified TiO2

    International Nuclear Information System (INIS)

    Wang, Xiaodong; Xue, Xiaoxiao; Liu, Xiaogang; Xing, Xing; Li, Qiuye; Yang, Jianjun

    2015-01-01

    Carbon-modified TiO 2 (CT) nanoparticles were prepared via a two-step method of heat treatment without the resorcinol-formaldehyde (RF) polymer. As-prepared CT nanoparticles were characterized by means of X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (UV–Vis/DRS), transmission electron microscopy (TEM), N 2 adsorption–desorption isotherms, thermal analysis (TA), electron spin resonance (ESR), and X-ray photoelectron spectroscopy (XPS). The visible light photocatalytic activities were evaluated on the basis of the degradation of methyl orange (MO). The synergistic effect of single-electron-trapped oxygen vacancies (SETOVs) and the carbon species on the visible light photocatalytic activities of the CT nanoparticles were discussed. It was found that the crystalline phase, the morphology, and particle size of the CT nanoparticles depended on the second heat-treatment temperature instead of the first heat-treatment temperature. The visible light photocatalytic activities were attributed to the synergistic effect of SETOVs and the carbon species, and also depended on the specific surface area of the photocatalysts. - Highlights: • Carbon-modified TiO 2 particles have been prepared without RF polymer. • The visible light photocatalytic activities of the particles have been evaluated. • The band gap energy structure of the carbon-modified TiO 2 has been proposed. • Synergistic effect of SETOVs and carbon species has been discussed. • The activities also depend on the specific surface area of the catalysts

  12. Highly Efficient Electrocatalysts for Oxygen Reduction Reaction Based on 1D Ternary Doped Porous Carbons Derived from Carbon Nanotube Directed Conjugated Microporous Polymers

    KAUST Repository

    He, Yafei

    2016-10-11

    © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.One-dimensional (1D) porous materials have shown great potential for gas storage and separation, sensing, energy storage, and conversion. However, the controlled approach for preparation of 1D porous materials, especially porous organic materials, still remains a great challenge due to the poor dispersibility and solution processability of the porous materials. Here, carbon nanotube (CNT) templated 1D conjugated microporous polymers (CMPs) are prepared using a layer-by-layer method. As-prepared CMPs possess high specific surface areas of up to 623 m2 g-1 and exhibit strong electronic interactions between p-type CMPs and n-type CNTs. The CMPs are used as precursors to produce heteroatom-doped 1D porous carbons through direct pyrolysis. As-produced ternary heteroatom-doped (B/N/S) 1D porous carbons possess high specific surface areas of up to 750 m2 g-1, hierarchical porous structures, and excellent electrochemical-catalytic performance for oxygen reduction reaction. Both of the diffusion-limited current density (4.4 mA cm-2) and electron transfer number (n = 3.8) for three-layered 1D porous carbons are superior to those for random 1D porous carbon. These results demonstrate that layered and core-shell type 1D CMPs and related heteroatom-doped 1D porous carbons can be rationally designed and controlled prepared for high performance energy-related applications.

  13. Radiation accelerated formation of oxygen and carbon related complexes in silicon

    International Nuclear Information System (INIS)

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

    1984-06-01

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

  14. Measurement of cell respiration and oxygenation in standard multichannel biochips using phosphorescent O2-sensitive probes.

    Science.gov (United States)

    Kondrashina, Alina V; Papkovsky, Dmitri B; Dmitriev, Ruslan I

    2013-09-07

    Measurement of cell oxygenation and oxygen consumption is useful for studies of cell bioenergetics, metabolism, mitochondrial function, drug toxicity and common pathophysiological conditions. Here we present a new platform for such applications which uses commercial multichannel biochips (μ-slides, Ibidi) and phosphorescent O2 sensitive probes. This platform was evaluated with both extracellular and intracellular O2 probes, several different cell types and treatments including mitochondrial uncoupling and inhibition, depletion of extracellular Ca(2+) and inhibition of V-ATPase and histone deacetylases. The results show that compared to the standard microwell plates currently used, the μ-slide platform provides facile O2 measurements with both suspension and adherent cells, higher sensitivity and reproducibility, and faster measurement time. It also allows re-perfusion and multiple treatments of cells and multi-parametric analyses in conjunction with other probes. Optical measurements are conducted on standard fluorescence readers and microscopes.

  15. 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.

  16. 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).

  17. Annual measurements of gain and loss in aboveground carbon density

    Science.gov (United States)

    Baccini, A.; Walker, W. S.; Carvalho, L.; Farina, M.; Sulla-menashe, D. J.; Houghton, R. A.

    2017-12-01

    Tropical forests hold large stores of carbon, but their net carbon balance is uncertain. Land use and land-cover change (LULCC) are believed to release between 0.81 and 1.14 PgC yr-1, while intact native forests are thought to be a net carbon sink of approximately the same magnitude. Reducing the uncertainty of these estimates is not only fundamental to the advancement of carbon cycle science but is also of increasing relevance to national and international policies designed to reduce emissions from deforestation and forest degradation (e.g., REDD+). Contemporary approaches to estimating the net carbon balance of tropical forests rely on changes in forest area between two periods, typically derived from satellite data, together with information on average biomass density. These approaches tend to capture losses in biomass due to deforestation (i.e., wholesale stand removals) but are limited in their sensitivity to forest degradation (e.g., selective logging or single-tree removals), which can account for additional biomass losses on the order of 47-75% of deforestation. Furthermore, while satellite-based estimates of forest area loss have been used successfully to estimate associated carbon losses, few such analyses have endeavored to determine the rate of carbon sequestration in growing forests. Here we use 12 years (2003-2014) of pantropical satellite data to quantify net annual changes in the aboveground carbon density of woody vegetation (MgC ha-1yr-1), providing direct, measurement-based evidence that the world's tropical forests are a net carbon source of 425.2 ± 92.0 Tg C yr-1. This net release of carbon consists of losses of 861.7 ± 80.2 Tg C yr-1 and gains of -436.5 ± 31.0 Tg C yr-1 . Gains result from forest growth; losses result from reductions in forest area due to deforestation and from reductions in biomass density within standing forests (degradation), with the latter accounting for 68.9% of overall losses. Our findings advance previous research

  18. Impact of upwelling events on the sea water carbonate chemistry and dissolved oxygen concentration in the Gulf of Papagayo (Culebra Bay, Costa Rica: Implications for coral reefs

    Directory of Open Access Journals (Sweden)

    Tim Rixen

    2012-04-01

    Full Text Available The Gulf of Papagayo, Pacific coast of Costa Rica, is one of the three seasonal upwelling areas of Mesoamerica. In April 2009, a 29-hour experiment was carried out at the pier of the Marina Papagayo, Culebra Bay. We determined sea surface temperature (SST, dissolved oxygen concentration, salinity, pH, and the partial pressure of CO2 (pCO2. The aragonite saturation state (Ωa as well as the other parameters of the marine carbonate system such as the total dissolved inorganic carbon (DIC and the total alkalinity (TA were calculated based on the measured pH and the pCO2. The entrainment of subsurface waters raised the pCO2 up to 645 µatm. SSTs, dissolved oxygen concentrations decreased form 26.4 to 23.7°C and from 228 to 144 µmol l-1. Ωa dropped down to values of 2.1. Although these changes are assumed to reduce the coral growth, the main reef building coral species within the region (Pocillopora spp. and Pavona clavus reveal growth rates exceeding those measured at other sites in the eastern tropical Pacific. This implies that the negative impact of upwelling on coral growth might be overcompensated by an enhanced energy supply caused by the high density of food and nutrients and more favorable condition for coral growth during the non-upwelling season.

  19. Limitations of quantitative photoacoustic measurements of blood oxygenation in small vessels

    International Nuclear Information System (INIS)

    Sivaramakrishnan, Mathangi; Maslov, Konstantin; Zhang, Hao F; Stoica, George; Wang, Lihong V

    2007-01-01

    We investigate the feasibility of obtaining accurate quantitative information, such as local blood oxygenation level (sO 2 ), with a spatial resolution of about 50 μm from spectral photoacoustic (PA) measurements. The optical wavelength dependence of the peak values of the PA signals is utilized to obtain the local blood oxygenation level. In our in vitro experimental models, the PA signal amplitude is found to be linearly proportional to the blood optical absorption coefficient when using ultrasonic transducers with central frequencies high enough such that the ultrasonic wavelengths are shorter than the light penetration depth into the blood vessels. For an optical wavelength in the 578-596 nm region, with a transducer central frequency that is above 25 MHz, the sensitivity and accuracy of sO 2 inversion is shown to be better than 4%. The effect of the transducer focal position on the accuracy of quantifying blood oxygenation is found to be negligible. In vivo oxygenation measurements of rat skin microvasculature yield results consistent with those from in vitro studies, although factors specific to in vivo measurements, such as the spectral dependence of tissue optical attenuation, dramatically affect the accuracy of sO 2 quantification in vivo

  20. Quantitative measurements of ground state atomic oxygen in atmospheric pressure surface micro-discharge array

    Science.gov (United States)

    Li, D.; Kong, M. G.; Britun, N.; Snyders, R.; Leys, C.; Nikiforov, A.

    2017-06-01

    The generation of atomic oxygen in an array of surface micro-discharge, working in atmospheric pressure He/O2 or Ar/O2 mixtures, is investigated. The absolute atomic oxygen density and its temporal and spatial dynamics are studied by means of two-photon absorption laser-induced fluorescence. A high density of atomic oxygen is detected in the He/O2 mixture with up to 10% O2 content in the feed gas, whereas the atomic oxygen concentration in the Ar/O2 mixture stays below the detection limit of 1013 cm-3. The measured O density near the electrode under the optimal conditions in He/1.75% O2 gas is 4.26  ×  1015 cm-3. The existence of the ground state O (2p 4 3 P) species has been proven in the discharge at a distance up to 12 mm away from the electrodes. Dissociative reactions of the singlet O2 with O3 and deep vacuum ultraviolet radiation, including the radiation of excimer \\text{He}2\\ast , are proposed to be responsible for O (2p 4 3 P) production in the far afterglow. A capability of the surface micro-discharge array delivering atomic oxygen to long distances over a large area is considered very interesting for various biomedical applications.

  1. Behaviour of atomic oxygen in a pulsed dielectric barrier discharge measured by laser-induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Ryo [High Temperature Plasma Center, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 227-8568 (Japan); Yamashita, Youta [Department of Electrical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan); Takezawa, Kei [Department of Electrical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan); Oda, Tetsuji [Department of Electrical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan)

    2005-08-21

    Atomic oxygen is measured in a pulsed dielectric barrier discharge (DBD) using two-photon absorption laser-induced fluorescence (TALIF). The ground-level atomic oxygen is excited to the 3p {sup 3}P state by two-photon absorption at 226 nm. Negative (-40 kV) or positive (+30 kV) pulsed DBD occurs in an O{sub 2}-N{sub 2} mixture at atmospheric pressure. The pulse width of the DBD current is approximately 50 ns. The TALIF experiment shows that the decay rate of atomic oxygen increases linearly with O{sub 2} concentration. This result proves that atomic oxygen decays mainly by the third-body reaction, O + O{sub 2} + M {yields} O{sub 3} + M. The rate coefficient of the third-body reaction is estimated to be 2.2 x 10{sup -34} cm{sup 6} s{sup -1} in the negative DBD and 0.89 x 10{sup -34} cm{sup 6} s{sup -1} in the positive DBD. It is shown that the decay rate of atomic oxygen increases linearly with humidity. This can explain the well-known fact that ozone production in DBD is suppressed by increasing humidity.

  2. Behaviour of atomic oxygen in a pulsed dielectric barrier discharge measured by laser-induced fluorescence

    International Nuclear Information System (INIS)

    Ono, Ryo; Yamashita, Youta; Takezawa, Kei; Oda, Tetsuji

    2005-01-01

    Atomic oxygen is measured in a pulsed dielectric barrier discharge (DBD) using two-photon absorption laser-induced fluorescence (TALIF). The ground-level atomic oxygen is excited to the 3p 3 P state by two-photon absorption at 226 nm. Negative (-40 kV) or positive (+30 kV) pulsed DBD occurs in an O 2 -N 2 mixture at atmospheric pressure. The pulse width of the DBD current is approximately 50 ns. The TALIF experiment shows that the decay rate of atomic oxygen increases linearly with O 2 concentration. This result proves that atomic oxygen decays mainly by the third-body reaction, O + O 2 + M → O 3 + M. The rate coefficient of the third-body reaction is estimated to be 2.2 x 10 -34 cm 6 s -1 in the negative DBD and 0.89 x 10 -34 cm 6 s -1 in the positive DBD. It is shown that the decay rate of atomic oxygen increases linearly with humidity. This can explain the well-known fact that ozone production in DBD is suppressed by increasing humidity

  3. Studies on the heterogeneous electron transport and oxygen reduction reaction at metal (Co, Fe) octabutylsulphonylphthalocyanines supported on multi-walled carbon nanotube modified graphite electrode

    CSIR Research Space (South Africa)

    Mamuru, SA

    2010-09-01

    Full Text Available Heterogeneous electron transfer dynamics and oxygen reduction reaction (ORR) activities using octabutylsulphonylphthalocyanine complexes of iron (FeOBSPc) and cobalt (CoOBSPc) supported on multi-walled carbon nanotube (MWCNT) platforms have been...

  4. Iron (II) tetrakis(diaquaplatinum) octacarboxyphthalocyanine supported on multi-walled carbon nanotubes as effective electrocatalyst for oxygen reduction reaction in alkaline medium

    CSIR Research Space (South Africa)

    Mamuru, SA

    2010-11-01

    Full Text Available Oxygen reduction reaction (ORR) in alkaline medium at iron (II) tetrakis (diaquaplatinum) octacarboxyphthalocyanine (PtFeOCPc) catalyst supported on multi-walled carbon nanotubes (MWCNTs) has been described. The ORR followed the direct 4-electron...

  5. Improvement of activated carbons as oxygen reduction catalysts in neutral solutions by ammonia gas treatment and their performance in microbial fuel cells

    KAUST Repository

    Watson, Valerie J.; Nieto Delgado, Cesar; Logan, Bruce E.

    2013-01-01

    Commercially available activated carbon (AC) powders from different precursor materials (peat, coconut shell, coal, and hardwood) were treated with ammonia gas at 700 C to improve their performance as oxygen reduction catalysts in neutral p

  6. Hybrid membrane using polyethersulfone-modification of multiwalled carbon nanotubes with silane agent to enhance high performance oxygen separation

    Directory of Open Access Journals (Sweden)

    Tutuk Djoko Kusworo

    2014-04-01

    Full Text Available Mixed matrix membrane comprising carbon nanotubes embedded in polymer matrix have become one of the emerging technologies. This study was investigated in order to study the effect of silane agent modification towards carbon nanotubes (CNT surface at different concentration on oxygen enrichment performances of asymmetric mixed matrix membrane. The modified carbon nanotubes were prepared by treating the carbon nanotubes with chemical modification using Dynasylan Ameo (DA silane agent to allow PES chains to be grafted on carbon nanotubes surface. The results from the FESEM, DSC and FTIR analysis confirmed that chemical modification on carbon nanotubes surface had taken place. Sieve-in-a-cage’ morphology observed shows the poor adhesion between polymer and unmodified CNT. The gas separation performance of the asymmetric flat sheet mixed matrix membranes with modified CNT were relatively higher compared to the unmodified CNT. Hence, coated hollow fiber mixed matrix membrane with chemical modification on CNT surface using (3-aminopropyl-triethoxy methyl silane agent can potentially enhance the gas separation performance of O2 and N2.

  7. Stable carbon, oxygen, and nitrogen, isotope analysis of plants from a South Asian tropical forest: Implications for primatology.

    Science.gov (United States)

    Roberts, Patrick; Blumenthal, Scott A; Dittus, Wolfgang; Wedage, Oshan; Lee-Thorp, Julia A

    2017-06-01

    Stable isotope analysis of primate tissues in tropical forest contexts is an increasingly popular means of obtaining information about niche distinctions among sympatric species, including preferences in feeding height, forest canopy density, plant parts, and trophism. However, issues of equifinality mean that feeding height, canopy density, as well as the plant parts and plant species consumed, may produce similar or confounding effects. With a few exceptions, researchers have so far relied largely on general principles and/or limited plant data from the study area as references for deducing the predominant drivers of primate isotope variation. Here, we explore variation in the stable carbon (δ 13 C), nitrogen (δ 15 N), and oxygen (δ 18 O) isotope ratios of 288 plant samples identified as important to the three primate species from the Polonnaruwa Nature Sanctuary, Sri Lanka, relative to plant part, season, and canopy height. Our results show that plant part and height have the greatest effect on the δ 13 C and δ 18 O measurements of plants of immediate relevance to the primates, Macaca sinica, Semnopithecus priam thersites, and Trachypithecus vetulus, living in this monsoonal tropical forest. We find no influence of plant part, height or season on the δ 15 N of measured plants. While the plant part effect is particularly pronounced in δ 13 C between fruits and leaves, differential feeding height, and plant taxonomy influence plant δ 13 C and δ 18 O differences in addition to plant organ. Given that species composition in different regions and forest types will differ, the results urge caution in extrapolating general isotopic trends without substantial local baselines studies. © 2017 Wiley Periodicals, Inc.

  8. Petro-structural, geochemical and carbon and oxygen isotopic study on carbonates crosscuting the Oman Ophiolite peridotites: evidence of polygenic CO2 trapping

    Science.gov (United States)

    Noël, J.; Godard, M.; Martinez, I.; Oliot, E.; Williams, M. J.; Rodriguez, O.; Chaduteau, C.; Gouze, P.

    2017-12-01

    Carbon trapping in ophiolitic peridotites contributes to the global carbon cycle between solid Earth and its outer envelopes (through subduction and/or modern alteration). To investigate this process, we performed petro-structural (microtomography, EBSD, EPMA) and geochemical studies (LA-ICP-MS, carbon and oxygen isotopes on bulk and minerals using SHRIMP) of harzburgites cored in the Oman Ophiolite. Studied harzburgites are highly serpentinized (> 90 %) and crosscut by 3 generations of carbonates (> 20 Vol%) with compositions from calcite to dolomite (Mg/Ca = 0-0.85). Type 1 carbonates are fine penetrative veinlets and mesh core after olivine. They have low REE (e.g., Yb = 0.08-0.23 x CI-chondrite) and negative Ce anomalies. They have δ13CPDB = -15.2 to 1.10‰ and δ18OSMOW = 17.5 to 33.7‰, suggesting precipitation temperatures up to 110°C. Type 2 carbonates are pluri-mm veins bounded by cm-thick serpentinized vein selvages, oriented dominantly parallel to mantle foliation. Dynamic recrystallization is observed, indicating polygenetic formation: well crystallized calcite with REE abundances similar to Type 1 carbonates are locally replaced by small dolomite and calcite grains with higher REE (e.g., Yb = 0.35-1.0 x CI-chondrite) and positive Gd anomaly. Type 2 carbonates have δ13CPDB = -12.6 to -4.1‰ and δ18OSMOW = 25.0 to 32.7‰, suggesting precipitation temperatures from 10 to 60°C. Type 3 carbonates are late pluri-mm to cm veins reactivating Type 2 veins. They consist of small grains of dolomite and calcite with REE abundances similar to recrystallized Type 2 carbonates. Type 3 carbonates have δ13CPDB = -8.3 to -5.8‰ and δ18OSMOW = 28.8 to 32.7‰, suggesting precipitation temperatures 100°C). Formation of carbonate veins (Type 2) indicates localization of fluid flux, while serpentinization remains the dominant alteration process. Low T carbonate veins (Type 3) remain the main flow path through ophiolitic peridotites. Our study suggests that

  9. Local carbon diffusion coefficient measurement in the S-1 spheromak

    International Nuclear Information System (INIS)

    Mayo, R.M.; Levinton, F.M.; Meyerhofer, D.D.; Chu, T.K.; Paul, S.F.; Yamada, M.

    1988-10-01

    The local carbon diffusion coefficient was measured in the S - 1 spheromak by detecting the radial spread of injected carbon impurity. The radial impurity density profile is determined by the balance of ionization and diffusion. Using measured local electron temperature T/sub e/ and density n/sub e/, the ionization rate is determined from which the particle diffusion coefficient is inferred. The results found in this work are consistent with Bohm diffusion. The absolute magnitude of D/sub /perpendicular// was determined to be (4/approximately/6) /times/ D/sub Bohm/. 25 refs., 13 figs., 2 tabs

  10. Effects of carbon dioxide insufflation on regional cerebral oxygenation during laparoscopic surgery in children: a prospective study.

    Science.gov (United States)

    Tuna, Ayca Tas; Akkoyun, Ibrahim; Darcin, Sevtap; Palabiyik, Onur

    2016-01-01

    Laparoscopic surgery has become a popular surgical tool when compared to traditional open surgery. There are limited data on pediatric patients regarding whether pneumoperitoneum affects cerebral oxygenation although end-tidal CO2 concentration remains normal. Therefore, this study was designed to evaluate the changes of cerebral oxygen saturation using near-infrared spectroscope during laparoscopic surgery in children. The study comprised forty children who were scheduled for laparoscopic (Group L, n=20) or open (Group O, n=20) appendectomy. Hemodynamic variables, right and left regional cerebral oxygen saturation (RrSO2 and LrSO2), fraction of inspired oxygen, end-tidal carbon dioxide pressure (PETCO2), peak inspiratory pressure (Ppeak), respiratory minute volume, inspiratory and end-tidal concentrations of sevoflurane and body temperature were recorded. All parameters were recorded after anesthesia induction and before start of surgery (T0, baseline), 15min after start of surgery (T1), 30min after start of surgery (T2), 45min after start of surgery (T3), 60min after start of surgery (T4) and end of the surgery (T5). There were progressive decreases in both RrSO2 and LrSO2 levels in both groups, which were not statistically significant at T1, T2, T3, T4. The RrSO2 levels of Group L at T5 were significantly lower than that of Group O. One patient in Group L had an rSO2 value <80% of the baseline value. Carbon dioxide insufflation during pneumoperitoneum in pediatric patients may not affect cerebral oxygenation under laparoscopic surgery. Copyright © 2015 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

  11. [Effects of carbon dioxide insufflation on regional cerebral oxygenation during laparoscopic surgery in children: a prospective study].

    Science.gov (United States)

    Tuna, Ayca Tas; Akkoyun, Ibrahim; Darcin, Sevtap; Palabiyik, Onur

    2016-01-01

    Laparoscopic surgery has become a popular surgical tool when compared to traditional open surgery. There are limited data on pediatric patients regarding whether pneumoperitoneum affects cerebral oxygenation although end-tidal CO2 concentration remains normal. Therefore, this study was designed to evaluate the changes of cerebral oxygen saturation using near-infrared spectroscope during laparoscopic surgery in children. The study comprised forty children who were scheduled for laparoscopic (Group L, n=20) or open (Group O, n=20) appendectomy. Hemodynamic variables, right and left regional cerebral oxygen saturation (RrSO2 and LrSO2), fraction of inspired oxygen, end-tidal carbon dioxide pressure (PETCO2), peak inspiratory pressure (Ppeak), respiratory minute volume, inspiratory and end-tidal concentrations of sevoflurane and body temperature were recorded. All parameters were recorded after anesthesia induction and before start of surgery (T0, baseline), 15min after start of surgery (T1), 30min after start of surgery (T2), 45min after start of surgery (T3), 60min after start of surgery (T4) and end of the surgery (T5). There were progressive decreases in both RrSO2 and LrSO2 levels in both groups, which were not statistically significant at T1, T2, T3, T4. The RrSO2 levels of Group L at T5 were significantly lower than that of Group O. One patient in Group L had an rSO2 value <80% of the baseline value. Carbon dioxide insufflation during pneumoperitoneum in pediatric patients may not affect cerebral oxygenation under laparoscopic surgery. Copyright © 2015 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

  12. Carbon dioxide euthanasia in rats: Oxygen supplementation minimizes signs of agitation and asphyxia

    NARCIS (Netherlands)

    Coenen, A.M.L.; Drinkenburg, W.H.I.M.; Hoenderken, R.; Luijtelaar, E.L.J.M. van

    1995-01-01

    This paper records the effects of carbon dioxide when used for euthanasia, on behaviour, electrical brain activity and heart rate in rats. Four different methods were used. Animals were placed in a box (a) that was completely filled with carbon dioxide; (b) into which carbon dioxide was streamed at

  13. Operational Limitations of Arctic Waste Stabilization Ponds: Insights from Modeling Oxygen Dynamics and Carbon Removal

    DEFF Research Database (Denmark)

    Ragush, Colin M.; Gentleman, Wendy C.; Hansen, Lisbeth Truelstrup

    2018-01-01

    Presented here is a mechanistic model of the biological dynamics of the photic zone of a single-cell arctic waste stabilization pond (WSP) for the prediction of oxygen concentration and the removal of oxygen-demanding substances. The model is an exploratory model to assess the limiting environmen...

  14. Enhanced Sulfate Reduction and Carbon Sequestration in Sediments Underlying the Core of the Arabian Sea Oxygen Minimum Zone

    Science.gov (United States)

    Fernandes, S. Q.; Mazumdar, A.; Peketi, A.; Bhattacharya, S.; Carvalho, M.; Da Silva, R.; Roy, R.; Mapder, T.; Roy, C.; Banik, S. K.; Ghosh, W.

    2017-12-01

    The oxygen minimum zone (OMZ) of the Arabian Sea in the northern Indian Ocean is one of the three major global sites of open ocean denitrification. The functionally anoxic water column between 150 to 1200 mbsl plays host to unique biogeochemical processes and organism interactions. Little is known, however, about the consequence of the low dissolved oxygen on the underlying sedimentary biogeochemical processes. Here we present, for the first time, a comprehensive investigation of sediment biogeochemistry of the Arabian Sea OMZ by coupling pore fluid analyses with microbial diversity data in eight sediment cores collected across a transect off the west coast of India in the Eastern Arabian Sea. We observed that in sediments underlying the core of the OMZ, high organic carbon sequestration coincides with a high diversity of all bacteria (the majority of which are complex organic matter hydrolyzers) and sulfate reducing bacteria (simple organic compound utilizers). Depth-integrated sulfate reduction rate also intensifies in this territory. These biogeochemical features, together with the detected shallowing of the sulfate-methane interface and buildup of pore-water sulfide, are all reflective of heightened carbon-sulfur cycling in the sediments underlying the OMZ core. Our data suggests that the sediment biogeochemistry of the OMZ is sensitive to minute changes in bottom water dissolved oxygen, and is dictated by the potential abundance and bioavailability of complex to simple carbon compounds which can stimulate a cascade of geomicrobial activities pertaining to the carbon-sulfur cycle. Our findings hold implications in benthic ecology and sediment diagenesis.

  15. Effect of germanium doping on the annealing characteristics of oxygen and carbon-related defects in Czochralski silicon

    International Nuclear Information System (INIS)

    Londos, C. A.; Andrianakis, A.; Sgourou, E. N.; Emtsev, V.; Ohyama, H.

    2010-01-01

    This paper is devoted to the annealing studies of defects produced in carbon-rich Ge-doped Czochralski-grown Si (Cz-Si) by 2 MeV electron irradiation. The annealing temperature of vacancy-oxygen (VO) complexes, carbon interstitial-oxygen interstitial (C i O i ), and carbon interstitial-carbon substitutional (C i C s ) pairs as well as the formation temperature of vacancy-two oxygen (VO 2 ) complexes are monitored as a function of Ge concentration. It has been established that the annealing of C i O i and C i C s defects remains practically unaffected by the Ge presence, whereas the annealing temperature of VO defects and the formation temperature of VO 2 complexes are substantially lowered at Ge concentrations larger than 1x10 19 cm -3 . The hydrostatic component of elastic strains introduced by Ge atoms in the Si crystal lattice was calculated. It appears to be very small, at least insufficient to exert a pronounced effect upon the annealing behavior of radiation-produced defects. This conclusion is in line with what is observed for the C i O i and C i C s species. In the case of VO, whose annealing process in Cz-Si is concurrently conducted by two reaction paths VO+O i →VO 2 and VO+Si I →O i , we suggest that the latter reaction in Ge-doped Cz-Si is enhanced by emitting self-interstitials (Si I ) from loosely bound self-interstitial clusters predominantly formed around Ge impurity atoms. As a result, the liberation of self-interstitials at lower annealing temperatures leads to an enhanced annealing of VO defects. An enhanced formation of VO 2 complexes at lower temperatures is also discussed in terms of other reactions running in parallel with the reaction VO+Si I →O i .

  16. Comparison of sodium carbonate-oxygen and sodium hydroxide-oxygen pretreatments on the chemical composition and enzymatic saccharification of wheat straw.

    Science.gov (United States)

    Geng, Wenhui; Huang, Ting; Jin, Yongcan; Song, Junlong; Chang, Hou-Min; Jameel, Hasan

    2014-06-01

    Pretreatment of wheat straw with a combination of sodium carbonate (Na2CO3) or sodium hydroxide (NaOH) with oxygen (O2) 0.5MPa was evaluated for its delignification ability at relatively low temperature 110°C and for its effect on enzymatic hydrolysis efficiency. In the pretreatment, the increase of alkali charge (as Na2O) up to 12% for Na2CO3 and 6% for NaOH, respectively, resulted in enhancement of lignin removal, but did not significantly degrade cellulose and hemicellulose. When the pretreated solid was hydrolyzed with a mixture of cellulases and hemicellulases, the sugar yield increased rapidly with the lignin removal during the pretreatment. A total sugar yield based on dry matter of raw material, 63.8% for Na2CO3-O2 and 71.9% for NaOH-O2 was achieved under a cellulase loading of 20FPU/g-cellulose. The delignification efficiency and total sugar yield from enzymatic hydrolysis were comparable to the previously reported results at much higher temperature without oxygen. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Hyperbaric oxygen for carbon monoxide poisoning : a systematic review and critical analysis of the evidence.

    Science.gov (United States)

    Buckley, Nicholas A; Isbister, Geoffrey K; Stokes, Barrie; Juurlink, David N

    2005-01-01

    Poisoning with carbon monoxide (CO) is an important cause of unintentional and intentional injury worldwide. Hyperbaric oxygen (HBO) enhances CO elimination and has been postulated to reduce the incidence of neurological sequelae. These observations have led some clinicians to use HBO for selected patients with CO poisoning, although there is considerable variability in clinical practice. This article assesses the effectiveness of HBO compared with normobaric oxygen (NBO) for the prevention of neurological sequelae in patients with acute CO poisoning. The following databases were searched: MEDLINE (1966 to present), EMBASE (1980 to present), and the Controlled Trials Register of the Cochrane Collaboration, supplemented by a manual review of bibliographies of identified articles and discussion with recognised content experts. All randomised controlled trials involving people acutely poisoned with CO, regardless of severity, were examined. The primary analysis included all trials from which data could be extracted. Sensitivity analysis examined trials with better validity (defined using the validated instrument of Jadad) and those enrolling more severely poisoned patients. Two reviewers independently extracted from each trial, including information on the number of randomised patients, types of participants, the dose and duration of the intervention, and the prevalence of neurological sequelae at follow-up. A pooled odds ratio (OR) for the presence of neurological symptoms at 1-month follow-up was calculated using a random effects model. Bayesian models were also investigated to illustrate the degree of certainty about clinical effectiveness. Eight randomised controlled trials were identified. Two had no evaluable data and were excluded. The remaining trials were of varying quality and two have been published only as abstracts. The severity of CO poisoning varied among trials. At 1-month follow-up after treatment, sequelae possibly related to CO poisoning were

  18. Correlation of oxygenation and perfusion sensitive MRI with invasive micro probe measurements in healthy mice brain

    International Nuclear Information System (INIS)

    Sedlacik, Jan; Fiehler, Jens; Reitz, Matthias; Schmidt, Nils O.; Bolar, Divya S.; Adalsteinsson, Elfar

    2015-01-01

    The non-invasive assessment of (patho-)physiological parameters such as, perfusion and oxygenation, is of great importance for the characterization of pathologies e.g., tumors, which may be helpful to better predict treatment response and potential outcome. To better understand the influence of physiological parameters on the investigated oxygenation and perfusion sensitive MRI methods, MRI measurements were correlated with subsequent invasive micro probe measurements during free breathing conditions of air, air+10% CO2 and 100% O2 in healthy mice brain. MRI parameters were the irreversible (R2), reversible (R2') and effective (R2*) transverse relaxation rates, venous blood oxygenation level assessed by quantitative blood oxygenation level dependent (qBOLD) method and cerebral blood flow (CBF) assessed by arterial spin labeling (ASL) using a 7T small animal MRI scanner. One to two days after MRI, tissue perfusion and pO2 were measured by Laser-Doppler flowmetry and fluorescence quenching micro probes, respectively. The tissue pO2 values were converted to blood oxygen saturation by using the Hill equation. The animals were anesthetized by intra peritoneal injection of ketamine-xylazine-acepromazine (10-2-0.3 mg/ml.kg). Results for normal/hypercapnia/hyperoxia conditions were: R2[s and -1] = 20.7/20.4/20.1, R2*[s and -1] = 31.6/29.6/25.9, R2'[s and 1] = 10.9/9.2/5.7, qBOLD venous blood oxygenation level = 0.43/0.51/0.56, CBF[ml.min and -1.100g and -1] = 70.6/105.5/81.8, Laser-Doppler flowmetry[a.u.] = 89.2/120.2/90.6 and pO2[mmHg] = 6.3/32.3/46.7. All parameters were statistically significantly different with P < 0.001 between all breathing conditions. All MRI and the corresponding micro probe measurements were also statistically significantly (P ≤ 0.03) correlated with each other. However, converting the tissue pO2 to blood oxygen saturation = 0.02/0.34/0.63, showed only very limited agreement with the qBOLD venous blood oxygenation level. We found good

  19. Correlation of oxygenation and perfusion sensitive MRI with invasive micro probe measurements in healthy mice brain

    Energy Technology Data Exchange (ETDEWEB)

    Sedlacik, Jan; Fiehler, Jens [University Medical Center Hamburg-Eppendorf, Hamburg (Germany). Neuroradiology; Reitz, Matthias; Schmidt, Nils O. [University Medical Center Hamburg-Eppendorf, Hamburg (Germany). Neurosurgery; Bolar, Divya S. [Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA (United States). Radiology; Adalsteinsson, Elfar [Massachusetts Institute of Technology, Cambridge, MA (United States). Electrical Engineering and Computer Science

    2015-05-01

    The non-invasive assessment of (patho-)physiological parameters such as, perfusion and oxygenation, is of great importance for the characterization of pathologies e.g., tumors, which may be helpful to better predict treatment response and potential outcome. To better understand the influence of physiological parameters on the investigated oxygenation and perfusion sensitive MRI methods, MRI measurements were correlated with subsequent invasive micro probe measurements during free breathing conditions of air, air+10% CO2 and 100% O2 in healthy mice brain. MRI parameters were the irreversible (R2), reversible (R2') and effective (R2*) transverse relaxation rates, venous blood oxygenation level assessed by quantitative blood oxygenation level dependent (qBOLD) method and cerebral blood flow (CBF) assessed by arterial spin labeling (ASL) using a 7T small animal MRI scanner. One to two days after MRI, tissue perfusion and pO2 were measured by Laser-Doppler flowmetry and fluorescence quenching micro probes, respectively. The tissue pO2 values were converted to blood oxygen saturation by using the Hill equation. The animals were anesthetized by intra peritoneal injection of ketamine-xylazine-acepromazine (10-2-0.3 mg/ml.kg). Results for normal/hypercapnia/hyperoxia conditions were: R2[s {sup and} -1] = 20.7/20.4/20.1, R2*[s {sup and} -1] = 31.6/29.6/25.9, R2'[s {sup and} 1] = 10.9/9.2/5.7, qBOLD venous blood oxygenation level = 0.43/0.51/0.56, CBF[ml.min {sup and} -1.100g {sup and} -1] = 70.6/105.5/81.8, Laser-Doppler flowmetry[a.u.] = 89.2/120.2/90.6 and pO2[mmHg] = 6.3/32.3/46.7. All parameters were statistically significantly different with P < 0.001 between all breathing conditions. All MRI and the corresponding micro probe measurements