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Sample records for oxidant study minos

  1. Study of Neutrino Interactions in MINOS

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Richa [Panjab Univ., Chandigarh (India)

    2014-01-01

    MINOS stands for Main Injector Neutrino Oscillation Search. It is a long baseline experiment located in the USA and is composed of two detectors. The Near Detector is at Fermilab, 1 km from the source of neutrinos. The Far Detector is in Minnesota at a distance of 735 km from the source. Both detectors are steel scintillator tracking calorimeters. MINOS searches for neutrino oscillations by comparing the neutrino energy spectrum at the Far Detector with that obtained from a prediction based on the spectrum at the Near Detector. The primary aim of MINOS is to measure the atmospheric oscillation parameters Δm2 32 and θ23. CPT symmetry requires that these parameters should be same for neutrinos and antineutrinos. Di erences between neutrino and antineutrino oscillations would be an indication of new physics beyond the neutrino-Standard Model ( SM). Additionally, violation of Lorentz or CPT symmetry could also give rise to oscillations di erent from that expected from the SM predictions, such as neutrino to antineutrino transitions.

  2. Studying neutrino oscillations using quasi-elastic events in MINOS

    Energy Technology Data Exchange (ETDEWEB)

    Kumaratunga, Sujeewa Terasita [Univ. of Minnesota, Minneapolis, MN (United States)

    2008-02-01

    MINOS (Main Injector Neutrino Oscillation Search), is a long baseline neutrino experiment designed to search for neutrino oscillations using two detectors at Fermi National Accelerator Laboratory, IL (Near Detector) and Soudan, MN (Far Detector). It will study vμ → vτ oscillations and make a measurement on the oscillation parameters, Δm$2\\atop{23}$ and sin223, via a vμ beam made at Fermilab. Charge current neutrino interactions in the MINOS detectors are of three types: quasi-elastic scattering (QEL), resonance scattering (RES) and deep inelastic scattering (DIS). Of these, quasi-elastic scattering leaves the cleanest signal with just one μ and one proton in the final state, thus rendering the reconstruction of the neutrino energy more accurate. This thesis will outline a method to separate QEL events from the others in the two detectors and perform a calculation of Δm$2\\atop{23}$ and sin223 using those events. The period under consideration was May 2005 to February 2006. The number of observed quasi-elastic events with energies below 10 GeV was 29, where the expected number was 60 ± 3. A fit to the energy distribution of these events gives Δm$2\\atop{23}$ = 2.91$+0.49\\atop{-0.53}$(stat)$+0.08\\atop{-0.09}$(sys) x 10-3 eV2 and sin223 = 0.990-0.180(stat)-0.030(sys).

  3. MINOS Calibration and NA49 Hadronic Production Studies

    Energy Technology Data Exchange (ETDEWEB)

    Morse, Robert James [Univ. of Sussex, Brighton (United Kingdom)

    2003-08-01

    An overview of the current status of the Main Injector Neutrino Oscillation Search (MINOS) is presented. MINOS is a long-baseline experiment with two detectors situated in North America. The near detector is based at the emission point of the NuMI beam at Fermilab, Chicago, the far detector is 735 km downstream in a disused iron mine in Soudan, Minnesota. A third detector, the calibration detector, is used to cross-calibrate these detectors by sampling different particle beams at CERN. A detailed description of the design and construction of the light-injection calibration system is included. Also presented are experimental investigations into proton-carbon collisions at 158 GeV/c carried out with the NA49 experiment at CERN. The NA49 experiment is a Time Projection Chamber (TPC) based experiment situated at CERN's North Area. It is a well established experiment with well known characteristics. The data gained from this investigation are to be used to parameterize various hadronic production processes in accelerator and atmospheric neutrino production. These hadronic production parameters will be used to improve the neutrino generation models used in calculating the neutrino oscillation parameters in MINOS.

  4. Studies of Nu-mu to Nu-e Oscillation Appearance in the MINOS Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Pereira e Sousa, Alexandre Bruno [Tufts Univ., Medford, MA (United States)

    2006-02-01

    The MINOS experiment uses a long baseline neutrino beam, measured 1 km downstream from its origin in the Near Detector at Fermilab, and 734 km later in the large underground Far Detector in the Soudan mine. By comparing these two measurements, MINOS can probe the atmospheric domain of the neutrino oscillation phenomenology with unprecedented precision. Besides the ability to perform a world leading determination of the Δm$2\\atop{23}$ and θ23 parameters, via vμ flux disappearance, MINOS has the potential to make a leading measurement of vμ → ve oscillations in the atmospheric sector by looking for ve appearance at the Far Detector. The observation of ve appearance, tantamount to establishing a non-zero value of the θ13 mixing angle, opens the way to studies of CP violation in the leptonic sector, the neutrino spectral mass pattern ordering and neutrino oscillations in matter, the driving motivations of the next generation of neutrino experiments. In this thesis, we study the MINOS potential for measuring θ13 in the context of the MINOS Mock Data Challenge using a multivariate discriminant analysis method. We show the method's validity in the application to ve event classification and background identification, as well as in its ability to identify a ve signal in a Mock Data sample generated with undisclosed parameters. An independent shower reconstruction method based on three-dimensional hit matching and clustering was developed, providing several useful discriminator variables used in the multivariate analysis method. We also demonstrate that within 2 years of running, MINOS has the potential to improve the current best limit on θ13, from the CHOOZ experiment, by a factor of 2.

  5. A study of muon neutrino disappearance in the MINOS detectors and the NuMI beam

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Jiajie [Univ. of South Carolina, Columbia, SC (United States)

    2010-01-01

    There is now substantial evidence that the proper description of neutrino involves two representations related by the 3 x 3 PMNS matrix characterized by either distinct mass or flavor. The parameters of this mixing matrix, three angles and a phase, as well as the mass differences between the three mass eigenstates must be determined experimentally. The Main Injector Neutrino Oscillation Search experiment is designed to study the flavor composition of a beam of muon neutrinos as it travels between the Near Detector at Fermi National Accelerator Laboratory at 1 km from the target, and the Far Detector in the Soudan iron mine in Minnesota at 735 km from the target. From the comparison of reconstructed neutrino energy spectra at the near and far location, precise measurements of neutrino oscillation parameters from muon neutrino disappearance and electron neutrino appearance are expected. It is very important to know the neutrino flux coming from the source in order to achieve the main goal of the MINOS experiment: precise measurements of the atmospheric mass splitting |Δm232|, sin2 θ23. The goal of my thesis is to accurately predict the neutrino flux for the MINOS experiment and measure the neutrino mixing angle and atmospheric mass splitting.

  6. A study of muon neutrino to electron neutrino oscillations in the MINOS experiment

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Tingjun [Stanford Univ., CA (United States)

    2009-03-01

    The observation of neutrino oscillations (neutrino changing from one flavor to another) has provided compelling evidence that the neutrinos have non-zero masses and that leptons mix, which is not part of the original Standard Model of particle physics. The theoretical framework that describes neutrino oscillation involves two mass scales (Δmatm2 and Δmsol2), three mixing angles (θ12, θ23, and θ13) and one CP violating phase (δCP). Both mass scales and two of the mixing angles (θ12 and θ23) have been measured by many neutrino experiments. The mixing angle θ13, which is believed to be very small, remains unknown. The current best limit on θ13 comes from the CHOOZ experiment: θ13 < 11° at 90% C.L. at the atmospheric mass scale. δCP is also unknown today. MINOS, the Main Injector Neutrino Oscillation Search, is a long baseline neutrino experiment based at Fermi National Accelerator Laboratory. The experiment uses a muon neutrino beam, which is measured 1 km downstream from its origin in the Near Detector at Fermilab and then 735 km later in the Far Detector at the Soudan mine. By comparing these two measurements, MINOS can obtain parameters in the atmospheric sector of neutrino oscillations. MINOS has published results on the precise measurement of Δmatm2 and θ23 through the disappearance of muon neutrinos in the Far Detector and on a search for sterile neutrinos by looking for a deficit in the number of neutral current interactions seen in the Far Detector. MINOS also has the potential to improve the limit on the neutrino mixing angle θ13 or make the first measurement of its value by searching for an electron neutrino appearance signal in the Far Detector. This is the focus of the study presented in this thesis. We developed a neural network based algorithm to

  7. Hormonal and lifestyle determinants of appendicular skeletal muscle mass in men: the MINOS study.

    Science.gov (United States)

    Szulc, Pawel; Duboeuf, François; Marchand, François; Delmas, Pierre D

    2004-08-01

    Aging-related sarcopenia is characterized by a loss of muscle mass and strength and increased fatigability. However, studies of its determinants in elderly men are scarce. We investigated risk factors for sarcopenia in a large cohort of men. We analyzed 845 men aged 45-85 y who belonged to the MINOS cohort. Lifestyle factors (physical activity, tobacco smoking, alcohol intake, caffeine intake) were evaluated by using a standardized questionnaire. Appendicular skeletal muscle mass (ASM) was estimated by using dual-energy X-ray absorptiometry. The relative appendicular skeletal muscle mass index (RASM) was calculated as ASM/body height(2.3). Apparent free testosterone concentration (AFTC) and free testosterone index (FTI) were calculated on the basis of concentrations of total testosterone and sex hormone-binding globulin. RASM decreased with age (r = -0.29, P values for AFTC, FTI, or 25-hydroxycholecalciferol [25(OH)D] were >2 SDs below the mean for young men had significantly lower RASM than did men with higher values. Men with sarcopenia, defined as the lowest quartile of RASM in the studied cohort (normal RASM, weighed significantly less, smoked more, and spent significantly less time on leisure-time activities. Sarcopenic men also had lower values for testosterone, AFTC, FTI, and 25(OH)D. In elderly men, low physical activity, tobacco smoking, thinness, low testosterone (AFTC and FTI), and decreased 25(OH)D concentrations are risk factors for sarcopenia.

  8. A model study of ozone in the eastern Mediterranean free troposphere during MINOS (August 2001)

    NARCIS (Netherlands)

    Roelofs, GJ; Scheeren, HA; Heland, J; Ziereis, H; Lelieveld, J

    2003-01-01

    A coupled tropospheric chemistry-climate model is used to analyze tropospheric ozone distributions observed during the MINOS campaign in the eastern Mediterranean region ( August, 2001). Modeled ozone profiles are generally in good agreement with the observations. Our analysis shows that the

  9. Muon neutrino disappearance at MINOS

    International Nuclear Information System (INIS)

    Armstrong, R.

    2009-01-01

    A strong case has been made by several experiments that neutrinos oscillate, although important questions remain as to the mechanisms and precise values of the parameters. In the standard picture, two parameters describe the nature of how the neutrinos oscillate: the mass-squared difference between states and the mixing angle. The purpose of this thesis is to use data from the MINOS experiment to precisely measure the parameters associated with oscillations first observed in studies of atmospheric neutrinos. MINOS utilizes two similar detectors to observe the oscillatory nature of neutrinos. The Near Detector, located 1 km from the source, observes the unoscillated energy spectrum while the Far Detector, located 735 km away, is positioned to see the oscillation signal. Using the data in the Near Detector, a prediction of the expected neutrino spectrum at the Far Detector assuming no oscillations is made. By comparing this prediction with the MINOS data, the atmospheric mixing parameters are measured to be Δm 32 2 = 2.45 +0.12 -0.12 x 10 -3 eV 2 and sin 2 (2θ 32 ) = 1.00 -0.04 +0.00 (> 0.90 at 90% confidence level).

  10. A model study of ozone in the eastern Mediterranean free troposphere during MINOS (August 2001

    Directory of Open Access Journals (Sweden)

    G. J. Roelofs

    2003-01-01

    Full Text Available A coupled tropospheric chemistry-climate model is used to analyze tropospheric ozone distributions observed during the MINOS campaign in the eastern Mediterranean region (August, 2001. Modeled ozone profiles are generally in good agreement with the observations. Our analysis shows that the atmospheric dynamics in the region are strongly influenced by the occurrence of an upper tropospheric anti-cyclone, associated with the Asian summer monsoon and centered over the Tibetan Plateau. The anti-cyclone affects the chemical composition of the upper troposphere, where ozone concentrations of about 50 ppbv were measured, through advection of boundary layer air from South-East Asia. A layer between 4-6 km thickness was present beneath, containing up to 120 ppbv of ozone with substantial contributions by transport from the stratosphere and through lightning NOx. Additionally, pollutant ozone from North America was mixed in. Ozone in the lower troposphere originated mainly from the European continent. The stratospheric influence may be overestimated due to too strong vertical diffusion associated with the relatively coarse vertical resolution. The estimated tropospheric ozone column over the eastern Mediterranean is ~50 DU in summer, to which ozone from recent stratospheric origin contributes about 30%, ozone from lightning 13%, and from South-East Asia, North America and Europe about 7%, 8% and 14%, respectively, adding to a long-term hemispheric background of 25% of the column.

  11. MINOS Sterile Neutrino Search

    Energy Technology Data Exchange (ETDEWEB)

    Koskinen, David Jason [Univ. College London, Bloomsbury (United Kingdom)

    2009-02-01

    The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline accelerator neutrino experiment designed to measure properties of neutrino oscillation. Using a high intensity muon neutrino beam, produced by the Neutrinos at Main Injector (NuMI) complex at Fermilab, MINOS makes two measurements of neutrino interactions. The first measurement is made using the Near Detector situated at Fermilab and the second is made using the Far Detector located in the Soudan Underground laboratory in northern Minnesota. The primary goal of MINOS is to verify, and measure the properties of, neutrino oscillation between the two detectors using the v μ→ Vτ transition. A complementary measurement can be made to search for the existence of sterile neutrinos; an oft theorized, but experimentally unvalidated particle. The following thesis will show the results of a sterile neutrino search using MINOS RunI and RunII data totaling ~2.5 x 1020 protons on target. Due to the theoretical nature of sterile neutrinos, complete formalism that covers transition probabilities for the three known active states with the addition of a sterile state is also presented.

  12. Role of the NO3 radicals in oxidation processes in the eastern Mediterranean troposphere during the MINOS campaign

    Directory of Open Access Journals (Sweden)

    M. Vrekoussis

    2004-01-01

    Full Text Available During the MINOS campaign (28 July-18 August 2001 the nitrate (NO3 radical was measured at Finokalia station, on the north coast of Crete in South-East Europe using a long path (10.4 km Differential Optical Absorption Spectroscopy instrument (DOAS. Hydroxyl (OH radical was also measured by a Chemical Ionization Mass-Spectrometer (Berresheim et al., 2003. These datasets represent the first simultaneous measurements of OH and NO3 radicals in the area. NO3 radical concentrations ranged from less than 3x107 up to 9x108 radicals· cm-3 with an average nighttime value of 1.1x108 radicals· cm-3. The observed NO3 mixing ratios are analyzed on the basis of the corresponding meteorological data and the volatile organic compound (VOC observations which were measured simultaneously at Finokalia station. The importance of the NO3 radical chemistry relatively to that of OH in the dimethylsulfide (DMS and nitrate cycles is also investigated. The observed NO3 levels regulate the nighttime variation of DMS. The loss of DMS by NO3 during night is about 75% of that by OH radical during day. NO3 and nitrogen pentoxide (N2O5 reactions account for about 21% of the total nitrate (HNO3(g+NO-3(g production.

  13. Sterile Neutrino Searches in MINOS and MINOS+ Experiments

    International Nuclear Information System (INIS)

    Huang, Junting

    2015-01-01

    This dissertation presents the searches on sterile neutrinos using the data collected in MINOS+ Experiment from September 2013 to September 2014, and the full data set of MINOS Experiment collected from 2005 to 2012. Anomalies in short baseline experiments, such as LSND and MiniBooNE, showed hints of sterile neutrinos, a type of neutrino that does not interact with the Standard Model particles. In this work, two models are considered: 3+1 and large extra dimension (LED). In the 3+1 model, one sterile neutrino state is added into the standard oscillation scheme consisting of three known active neutrino states v e , v μ and v τ . In the LED model, sterile neutrinos arise as Kaluza-Klein (KK) states due to assumed large extra dimensions. Mixing between sterile and active neutrino states may modify the oscillation patterns observed in the MINOS detectors. Both searches yield null results. For 3+1, a combined fit of MINOS and MINOS+ data gives a stronger limit on θ 24 in the range of 10 -2 eV 2 < Δm 43 2 < 1 eV 2 than previous experiments. For LED, with the complete MINOS data set, the size of extra dimensions is constrained to be smaller than ~ 0.35 μm at 90% C.L. in the limit of a vanishing lightest neutrino mass.

  14. Sterile Neutrino Searches in MINOS and MINOS+ Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Junting [Univ. of Texas, Austin, TX (United States)

    2015-05-01

    This dissertation presents the searches on sterile neutrinos using the data collected in MINOS+ Experiment from September 2013 to September 2014, and the full data set of MINOS Experiment collected from 2005 to 2012. Anomalies in short baseline experiments, such as LSND and MiniBooNE, showed hints of sterile neutrinos, a type of neutrino that does not interact with the Standard Model particles. In this work, two models are considered: 3+1 and large extra dimension (LED). In the 3+1 model, one sterile neutrino state is added into the standard oscillation scheme consisting of three known active neutrino states ve, vμ and vτ. In the LED model, sterile neutrinos arise as Kaluza-Klein (KK) states due to assumed large extra dimensions. Mixing between sterile and active neutrino states may modify the oscillation patterns observed in the MINOS detectors. Both searches yield null results. For 3+1, a combined fit of MINOS and MINOS+ data gives a stronger limit on θ24 in the range of 10-2 eV2 < Δm412 < 1 eV2 than previous experiments. For LED, with the complete MINOS data set, the size of extra dimensions is constrained to be smaller than ~ 0.35 μm at 90% C.L. in the limit of a vanishing lightest neutrino mass.

  15. Preliminary Measurement of Neutrino Oscillation Parameters By NuMI/MINOS and Calibration Studies for Improving this Measurement

    International Nuclear Information System (INIS)

    Symes, Philip Andrew; Sussex U.

    2005-01-01

    This thesis explains the origins of neutrinos and their interactions, and the phenomenon of neutrino oscillations. Experiments for measuring neutrino oscillations are mentioned and the experiment investigated in this thesis, the ''Main Injector Neutrino Oscillation Search'', and its neutrino beam, the Fermi National Accelerator Laboratory's ''Neutrinos At The Main Injector'', are described. MINOS is a long baseline (735 km) neutrino oscillation experiment with a near and a far detector, intended to make precision measurements of the atmospheric sector neutrino oscillation parameters. A measurement is made of the ''atmospheric'' neutrino oscillation parameters, Δm 23 2 and sin 2 (2θ 23 ), using neutrinos from the NuMI beam. The results of this analysis are compared to measurements at MINOS using neutrinos from the atmosphere and with other experiments. A more detailed method of beam neutrino analysis is discussed, and the extra calibrations needed to perform that analysis properly are described, with special attention paid to two aspects of the calibration, which comprise the bulk of work for this thesis. The light injection calibration system uses LEDs to illuminate the detector readout and provides a normalization of the stability of the detector over time. The hardware and different modi operandi of the system are described. There is a description of installation and commissioning of the system at one of the MINOS detectors. The response normalization of each detector with cosmic ray muons is described. Special attention is paid to the explanation of necessary corrections that must be made to the muon sample in order for the sample to be used to calibrate each detector to the specified accuracy. The performance of the calibration is shown

  16. Preliminary Measurement of Neutrino Oscillation Parameters By NuMI/MINOS and Calibration Studies for Improving this Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Symes, Philip Andrew [Univ. of Sussex, Brighton (United Kingdom)

    2005-11-01

    This thesis explains the origins of neutrinos and their interactions, and the phenomenon of neutrino oscillations. Experiments for measuring neutrino oscillations are mentioned and the experiment investigated in this thesis, the ''Main Injector Neutrino Oscillation Search'', and its neutrino beam, the Fermi National Accelerator Laboratory's ''Neutrinos At The Main Injector'', are described. MINOS is a long baseline (735 km) neutrino oscillation experiment with a near and a far detector, intended to make precision measurements of the atmospheric sector neutrino oscillation parameters. A measurement is made of the ''atmospheric'' neutrino oscillation parameters, Δm$2\\atop{23}$ and sin2(2θ23), using neutrinos from the NuMI beam. The results of this analysis are compared to measurements at MINOS using neutrinos from the atmosphere and with other experiments. A more detailed method of beam neutrino analysis is discussed, and the extra calibrations needed to perform that analysis properly are described, with special attention paid to two aspects of the calibration, which comprise the bulk of work for this thesis. The light injection calibration system uses LEDs to illuminate the detector readout and provides a normalization of the stability of the detector over time. The hardware and different modi operandi of the system are described. There is a description of installation and commissioning of the system at one of the MINOS detectors. The response normalization of each detector with cosmic ray muons is described. Special attention is paid to the explanation of necessary corrections that must be made to the muon sample in order for the sample to be used to calibrate each detector to the specified accuracy. The performance of the calibration is shown.

  17. Atmospheric Neutrinos in the MINOS Far Detector

    Energy Technology Data Exchange (ETDEWEB)

    Howcroft, Caius Leo Frederick [Univ. of Cambridge (United Kingdom)

    2004-12-01

    The phenomenon of flavour oscillations of neutrinos created in the atmosphere was first reported by the Super-Kamiokande collaboration in 1998 and since then has been confirmed by Soudan 2 and MACRO. The MINOS Far Detector is the first magnetized neutrino detector able to study atmospheric neutrino oscillations. Although it was designed to detect neutrinos from the NuMI beam, it provides a unique opportunity to measure the oscillation parameters for neutrinos and anti-neutrinos independently. The MINOS Far Detector was completed in August 2003 and since then has collected 2.52 kton-years of atmospheric data. Atmospheric neutrino interactions contained within the volume of the detector are separated from the dominant background from cosmic ray muons. Thirty seven events are selected with an estimated background contamination of less than 10%. Using the detector's magnetic field, 17 neutrino events and 6 anti-neutrino events are identified, 14 events have ambiguous charge. The neutrino oscillation parameters for vμ and $\\bar{v}$μ are studied using a maximum likelihood analysis. The measurement does not place constraining limits on the neutrino oscillation parameters due to the limited statistics of the data set analysed. However, this thesis represents the first observation of charge separated atmospheric neutrino interactions. It also details the techniques developed to perform atmospheric neutrino analyses in the MINOS Far Detector.

  18. Hadronic interactions in the MINOS detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kordosky, Michael Alan [Univ. of Texas, Austin, TX (United States)

    2004-08-01

    MINOS, the Main Injector Neutrino Oscillation Search, will study neutrino flavor transformations using a Near detector at the Fermi National Accelerator Laboratory and a Far detector located in the Soudan Underground Laboratory in northern Minnesota. The MINOS collaboration also constructed the CalDet (calibration detector), a smaller version of the Near and Far detectors, to determine the topological and signal response to hadrons, electrons and muons. The detector was exposed to test-beams in the CERN Proton Synchrotron East Hall during 2001-2003, where it collected events at momentum settings between 200 MeV/c and 10 GeV/c. In this dissertation we present results of the CalDet experiment, focusing on the topological and signal response to hadrons. We briefly describe the MINOS experiment and its iron-scintillator tracking-sampling calorimters as a motivation for the CalDet experiment. We discuss the operation of the CalDet in the beamlines as well as the trigger and particle identification systems used to isolate the hadron sample. The method used to calibrate the MINOS detector is described and validated with test-beam data. The test-beams were simulated to model the muon flux, energy loss upstream of the detector and the kaon background. We describe the procedure used to discriminate between pions and muons on the basis of the event topology. The hadron samples were used to benchmark the existing GEANT3 based hadronic shower codes and determine the detector response and resolution for pions and protons. We conclude with comments on the response to single hadrons and to neutrino induced hadronic showers.

  19. Two investigational glycylcyclines, DMG-DMDOT and DMG-MINO. Antimicrobial activity studies against gram-positive species.

    Science.gov (United States)

    Johnson, D M; Jones, R N

    1996-01-01

    DMG-DMDOT (CL-331,002 OR CL-331,928) and DMG-MINO (CL-329,998 or CL-344,677) are two new semisynthetic tetracyclines called glycylcyclines, with a broad spectrum of activity and includes Enterobacteriaceae, Gram-positive cocci, JK diphtheroids, and Bacillus cereus. Potent activity was demonstrated against all Streptococcus spp. strains [minimum inhibitory concentrations] (MIC90S) 0.06-0.25 micrograms/ml) and staphylococci (oxacillin susceptible ans resistant; MIC90S 0.12-2 micrograms/ml). Both glycylcyclines (MIC90, 0.06 micrograms/ml) were more potent than minocycline (MIC90 8 micrograms/ml) against Enterococcus faecium, many of which were vancomycin resistant (116 strains). Organisms with minocycline MICs at > or = 8 micrograms/ml (Staphylococcus aureus, enterococci, beta-hemolytic streptococci, and pneumococci) had glycylcycline MIC results ranging from 0.06 to 0.5 micrograms/ml (e.g., apparent use against existing tetracycline-resistance phenotypes). Drugs in this class appear promising for therapy of infections caused by Gram-positive species now testing resistant to contemporary antimicrobial agents, and further development of compounds in this class is encouraged.

  20. Sterile Neutrino Search with MINOS

    International Nuclear Information System (INIS)

    Devan, Alena V.

    2015-01-01

    MINOS, Main Injector Neutrino Oscillation Search, is a long-baseline neutrino oscillation experiment in the NuMI muon neutrino beam at the Fermi National Accelerator Laboratory in Batavia, IL. It consists of two detectors, a near detector positioned 1 km from the source of the beam and a far detector 734 km away in Minnesota. MINOS is primarily designed to observe muon neutrino disappearance resulting from three flavor oscillations. The Standard Model of Particle Physics predicts that neutrinos oscillate between three active flavors as they propagate through space. This means that a muon-type neutrino has a certain probability to later interact as a different type of neutrino. In the standard picture, the neutrino oscillation probabilities depend only on three neutrino flavors and two mass splittings, Δm 2 . An anomaly was observed by the LSND and MiniBooNE experiments that suggests the existence of a fourth, sterile neutrino flavor that does not interact through any of the known Standard Model interactions. Oscillations into a theoretical sterile flavor may be observed by a deficit in neutral current interactions in the MINOS detectors. A distortion in the charged current energy spectrum might also be visible if oscillations into the sterile flavor are driven by a large mass-squared difference, Δm s 2 ~ 1 eV 2 . The results of the 2013 sterile neutrino search are presented here.

  1. Sterile Neutrino Search with MINOS

    Energy Technology Data Exchange (ETDEWEB)

    Devan, Alena V. [College of William and Mary, Williamsburg, VA (United States)

    2015-08-01

    MINOS, Main Injector Neutrino Oscillation Search, is a long-baseline neutrino oscillation experiment in the NuMI muon neutrino beam at the Fermi National Accelerator Laboratory in Batavia, IL. It consists of two detectors, a near detector positioned 1 km from the source of the beam and a far detector 734 km away in Minnesota. MINOS is primarily designed to observe muon neutrino disappearance resulting from three flavor oscillations. The Standard Model of Particle Physics predicts that neutrinos oscillate between three active flavors as they propagate through space. This means that a muon-type neutrino has a certain probability to later interact as a different type of neutrino. In the standard picture, the neutrino oscillation probabilities depend only on three neutrino flavors and two mass splittings, Δm2. An anomaly was observed by the LSND and MiniBooNE experiments that suggests the existence of a fourth, sterile neutrino flavor that does not interact through any of the known Standard Model interactions. Oscillations into a theoretical sterile flavor may be observed by a deficit in neutral current interactions in the MINOS detectors. A distortion in the charged current energy spectrum might also be visible if oscillations into the sterile flavor are driven by a large mass-squared difference, ms2 ~ 1 eV2. The results of the 2013 sterile neutrino search are presented here.

  2. Neutrino induced events in the MINOS detectors

    International Nuclear Information System (INIS)

    Litchfield, Reuben Phillip

    2008-01-01

    The MINOS experiment is designed to study neutrino oscillations. It uses an accelerator generated beam of neutrinos and two detectors, the smaller at a distance of 1km and the larger at 735 km. By comparing the spectrum and flavour composition of the beam at the two detectors precise determinations of the oscillation parameters are possible. This thesis concentrates on the analysis of data from the larger Far Detector. By studying the spectrum of neutral current events it is possible to look for evidence of non-interacting 'sterile' neutrinos. The thesis describes how events are selected for this analysis, and a method for discriminating between charged current and neutral current events. The systematic uncertainties resulting from these cuts are evaluated. Several techniques for using Near Detector data to eliminate systematic uncertainties in the predicted Far Detector spectrum are compared. An oscillation analysis, based on the first year of MINOS data, uses the selected events to make a measurement of f s , the fraction of unseen neutrinos that are sterile. The measured value is f s = 0.07 +0.32 at 68%C.L., and is consistent with the standard three-neutrino picture, which has no sterile neutrino

  3. Neutrino induced events in the MINOS detectors

    Energy Technology Data Exchange (ETDEWEB)

    Litchfield, Reuben Phillip [Univ. of Oxford (United Kingdom). Keble College

    2008-01-01

    The MINOS experiment is designed to study neutrino oscillations. It uses an accelerator generated beam of neutrinos and two detectors, the smaller at a distance of 1km and the larger at 735 km. By comparing the spectrum and flavour composition of the beam at the two detectors precise determinations of the oscillation parameters are possible. This thesis concentrates on the analysis of data from the larger Far Detector. By studying the spectrum of neutral current events it is possible to look for evidence of non-interacting 'sterile' neutrinos. The thesis describes how events are selected for this analysis, and a method for discriminating between charged current and neutral current events. The systematic uncertainties resulting from these cuts are evaluated. Several techniques for using Near Detector data to eliminate systematic uncertainties in the predicted Far Detector spectrum are compared. An oscillation analysis, based on the first year of MINOS data, uses the selected events to make a measurement of f{sub s}, the fraction of unseen neutrinos that are sterile. The measured value is fs = 0.07+0.32 at 68%C.L., and is consistent with the standard three-neutrino picture, which has no sterile neutrino.

  4. Estudo da Oscilação de Neutrinos Muônicos Usando Dados Atmosféricos e de Acelerador nos Experimentos MINOS e MINOS+

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, Michelle Mesquita de [Federal Univ. of Goiás, Goiania, GO (Brazil)

    2015-01-01

    The MINOS (Main Injector Neutrino Oscillation Search) and MINOS+ experiments were designed to study neutrino oscillations using a muon neutrino beam which is detected in two different locations, in the Near Detector and in the Far Detector. The distance between the detectors allows the beam neutrinos to oscillate to a different flavor. Therefore, a disappearance of the muon neutrinos from the beam is observed in the Far Detector. The Far Detector has a special apparatus which makes possible the selection of atmospheric neutrinos and antineutrinos. These come from interactions of cosmic rays with the Earth’s atmosphere. Both detectors have a magnetic field, allowing the distiction between neutrinos and antineutrinos interactions. This thesis presents the first combined analysis of data from the MINOS and MINOS+ experiments. We have analyzed the combined neutrino energy spectrum from the complete MINOS beam data and the first, more energetic, MINOS+ beam data. The disappearance of the muon neutrinos was observed and the data has shown to be congruent with the oscillation model. Beyond that, we have measured the atmospheric oscillation parameters of the beam and atmospheric neutrinos and antineutrinos from MINOS combined with the atmospheric neutrinos and antineutrinos from MINOS+. Assuming the same oscillation parameters for both neutrinos and antineutrinos, the best fit is obtained for inverted hierarchy and lower octant with Δm2 32 = 2:37 X 10-3 eV2 and sin2 θ 23 = 0:43, and the limits m2 32 = [2,29 - 2,49] 10-3 eV2 (68%) and sin2 θ23 = 0.36 - 0.66 (90%). These results are the most precise measurement of the neutrinos mass splitting using muon neutrino disappearance data only.

  5. A new monitoring data tool for MINOS+

    International Nuclear Information System (INIS)

    Castromonte, Cesar; Gomes, Ricardo A.

    2013-01-01

    Full text: Monitoring the data taking process is one of the most important and critical parts of every High Energy Physics (HEP) experiment. This guarantees the reliability and good quality of the data taken. It also allows detecting and tracking down the different problems associated with the detector operations. The MINOS+ experiment is the continuation of the former MINOS neutrino experiment, which operated from August 2003 to April 2012. MINOS+ will continue exposing the two MINOS detectors (Near and Far) to the NuMI muon neutrino beam for three years starting in 2013. The medium energy setting of the NuMI beam projected for NO νA will deliver about 18 X 10 20 protons-on-target during the first three years of operation. This will allow the MINOS Far Detector to collect more than 10,000 charged current muon neutrino events in the 4-10 GeV energy range, providing an accurate test for non-standard neutrino interactions, sterile neutrinos, extra dimensions, neutrino time-of-flight, and perhaps more. In this poster we show the full MINOS+ monitoring process, how this process is done, the several tools used to perform this task, and specially, the web monitoring data tool developed and implemented by the HEP group of the Federal University of Goiania as a contribution for the MINOS+ experiment. (author)

  6. A new monitoring data tool for MINOS+

    Energy Technology Data Exchange (ETDEWEB)

    Castromonte, Cesar; Gomes, Ricardo A. [Universidade Federal de Goias, Goiania (Brazil)

    2013-07-01

    Full text: Monitoring the data taking process is one of the most important and critical parts of every High Energy Physics (HEP) experiment. This guarantees the reliability and good quality of the data taken. It also allows detecting and tracking down the different problems associated with the detector operations. The MINOS+ experiment is the continuation of the former MINOS neutrino experiment, which operated from August 2003 to April 2012. MINOS+ will continue exposing the two MINOS detectors (Near and Far) to the NuMI muon neutrino beam for three years starting in 2013. The medium energy setting of the NuMI beam projected for NO νA will deliver about 18 X 10{sup 20} protons-on-target during the first three years of operation. This will allow the MINOS Far Detector to collect more than 10,000 charged current muon neutrino events in the 4-10 GeV energy range, providing an accurate test for non-standard neutrino interactions, sterile neutrinos, extra dimensions, neutrino time-of-flight, and perhaps more. In this poster we show the full MINOS+ monitoring process, how this process is done, the several tools used to perform this task, and specially, the web monitoring data tool developed and implemented by the HEP group of the Federal University of Goiania as a contribution for the MINOS+ experiment. (author)

  7. Remote MINOS Shift Station at IF-UFG

    International Nuclear Information System (INIS)

    Tognini, Stefano Castro; Gomes, Ricardo Avelino

    2011-01-01

    Full text: MINOS is a very well known neutrino experiment mainly designed to study neutrino oscillations and measure the parameters that rule the phenomena. The experiment uses an intense neutrino beam provided by the NuMI (Neutrinos at the Main Injector) beamline at Fermilab and two similar magnetized detectors - the Near Detector located at Fermilab, 1 km downstream the target and 94 m underground; and the Far Detector located in the Soudan Mine in northern Minnesota, 734 km downstream the Near Detector and 713 m underground. The MINOS control room is consisted of four main systems used to monitor the beam, the detectors and the data acquisition process: the Beam Monitoring System - a set of tools used to monitor the status of the NuMI beam, such as its intensity, its alignment with the target and beamline and if the beam data acquisition is working properly; the Online Monitoring System (OM) - responsible for monitoring the electronics of both detectors, which determines the quality of the data; the Detector Control System (DCS) - which monitors the detectors information, such as the high voltage systems, state of the rack protection system, the magnet control, chiller monitor, coil current, humidity and environmental temperatures; and the Data Acquisition System (DAQ) - used to control the runs/subruns and monitor the recording process. The experiment is taking data with the Far Detector since 2003 and with the Near Detector since 2005. The Physics Institute of the Federal University of Goias (IF-UFG) is joining the MINOS Collaboration since June 2009 and this work describes the configuration of our Remote MINOS Shift Station. In order to accomplish the shift tasks with minimum expenditure of time and money efforts, MINOS decided to authorize remote shifts on January 2011. Apart of being able to realize remote shifts, the main goals of our shift station are to allow the training of new users, in particular graduate students; to allow our real-time monitoring of

  8. A search for sterile neutrinos in MINOS

    Energy Technology Data Exchange (ETDEWEB)

    Osiecki, Thomas Henry [Univ. of Texas, Austin, TX (United States)

    2007-01-01

    MINOS, the Main Injector Neutrino Oscillation Search, is a long baseline neutrino oscillation experiment based at Fermilab National Accelerator Laboratory. The experiment uses a neutrino beam, which is measured 1 km downstream from its origin in the Near detector at Fermilab and then 735 km later in the Far detector at the Soudan mine. By comparing these two measurements, MINOS can attain a very high precision for parameters in the atmospheric sector of neutrino oscillations. In addition to precisely determining Δm$2\\atop{23}$ and θ23 through the disappearance of vμ, MINOS is able to measure vμ → vsterile by looking for a deficit in the number of neutral current interactions seen in the Far detector. In this thesis, we present the results of a search for sterile neutrinos in MINOS.

  9. A search for sterile neutrinos in MINOS

    International Nuclear Information System (INIS)

    Osiecki, Thomas Henry

    2007-01-01

    MINOS, the Main Injector Neutrino Oscillation Search, is a long baseline neutrino oscillation experiment based at Fermilab National Accelerator Laboratory. The experiment uses a neutrino beam, which is measured 1 km downstream from its origin in the Near detector at Fermilab and then 735 km later in the Far detector at the Soudan mine. By comparing these two measurements, MINOS can attain a very high precision for parameters in the atmospheric sector of neutrino oscillations. In addition to precisely determining Δm 23 2 and θ 23 through the disappearance of ν μ , MINOS is able to measure ν μ → ν sterile by looking for a deficit in the number of neutral current interactions seen in the Far detector. In this thesis, we present the results of a search for sterile neutrinos in MINOS

  10. Electromagnetic interactions in the MINOS detectors

    Energy Technology Data Exchange (ETDEWEB)

    Vahle, Patricia LaVern [Univ. of Texas, Austin, TX (United States)

    2004-08-01

    MINoS is a long-baseline neutrino experiment designed to observe the oscillation of neutrinos traveling between two detectors, a Near Detector at Fermi National Accelerator Laboratory and a Far Detector at the Soudan Underground Laboratory in northern Minnesota. Precision measurement of the oscillation parameters requires a better than 5% absolute energy calibration with is derived using a dedicated calibration detector, called CalDet. A smaller version of the MINOS detectors, the CalDet was exposed to particular beams in the CERN PS East Area test beams in 2001-2003. This document describes the conditions under which the CalDet beam data were taken, establishes selection criteria to identify a sample of electrons, and discusses the characteristics of electromagnetic interactions in the CalDet.

  11. Discussion of Minos Mine operating system

    Energy Technology Data Exchange (ETDEWEB)

    Pan, B.

    1991-10-01

    The MINOS (mine operating system), which is used in the majority of British collieries, provides central control at the surface for the machinery and environmental equipment distributed throughout the mine. Installed equipment, including face machinery, conveyors, pumps, fans and sensors are connected to local outstations which all communicate with the control system via a single run of signal cable. The article discusses the system particularly its use in the Automated Control System of Underground Mining Locomotives (ACSUML). The discussion includes the use of MINOS to improve wagon identification, the operating principle of ACSUML and the possibilities of a driverless locomotive. 2 figs.

  12. Muon Energy Calibration of the MINOS Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Miyagawa, Paul S. [Somerville College, Oxford (United Kingdom)

    2004-01-01

    MINOS is a long-baseline neutrino oscillation experiment designed to search for conclusive evidence of neutrino oscillations and to measure the oscillation parameters precisely. MINOS comprises two iron tracking calorimeters located at Fermilab and Soudan. The Calibration Detector at CERN is a third MINOS detector used as part of the detector response calibration programme. A correct energy calibration between these detectors is crucial for the accurate measurement of oscillation parameters. This thesis presents a calibration developed to produce a uniform response within a detector using cosmic muons. Reconstruction of tracks in cosmic ray data is discussed. This data is utilized to calculate calibration constants for each readout channel of the Calibration Detector. These constants have an average statistical error of 1.8%. The consistency of the constants is demonstrated both within a single run and between runs separated by a few days. Results are presented from applying the calibration to test beam particles measured by the Calibration Detector. The responses are calibrated to within 1.8% systematic error. The potential impact of the calibration on the measurement of oscillation parameters by MINOS is also investigated. Applying the calibration reduces the errors in the measured parameters by ~ 10%, which is equivalent to increasing the amount of data by 20%.

  13. Electron Neutrino Appearance in the MINOS Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Holin, Anna Maria [Univ. College London, Bloomsbury (United Kingdom)

    2010-02-01

    The MINOS experiment is a long-baseline neutrino oscillation experiment which sends a high intensity muon neutrino beam through two functionally identical detectors, a Near detector at the Fermi National Accelerator Laboratory in Illinois, 1km from the beam source, and a Far detector, 734km away, in the Soudan Mine in Minnesota. MINOS may be able to measure the neutrino mixing angle parameter sin213 for the rst time. Detector granularity, however, makes it very hard to distinguish any e appearance signal events characteristic of a non-zero value of θ 13 from background neutral current (NC) and short-track vμ charged current (CC) events. Also, uncertainties in the hadronic shower modeling in the kinematic region characteristic of this analysis are relatively large. A new data-driven background decomposition method designed to address those issues is developed and its results presented. By removing the long muon tracks from vμ-CC events, the Muon Removed Charge Current (MRCC) method creates independent pseudo-NC samples that can be used to correct the MINOS Monte Carlo to agree with the high-statistics Near detector data and to decompose the latter into components so as to predict the expected Far detector background. The MRCC method also provides an important cross-check in the Far detector to test the background in the signal selected region. MINOS finds a 1.0-1.5 σ ve-CC excess above background in the Far detector data, depending on method used, for a total exposure of 3.14 x 1020 protons-on-target. Interpreting this excess as signal, MINOS can set limits on sin213. Using the MRCC method, MINOS sets a limit of sin2 2 θ 13 < 0.265 at the 90% confidence limit for a CP-violating phase δ = 0.

  14. Louise Erdrich: The Aesthetics of Mino bimaadiziwin

    OpenAIRE

    Madsen, Deborah Lea

    2011-01-01

    This article is the editorial introduction to the collection of essays entitled Louise Erdrich. An overview of Erdrich's literary innovations is offered in three sections that explain her relationship to Native place; the Native American historical contexts upon which her writing draws; and the specifically Ojibwe tribal contexts that inform her literary worldview. The discussions cohere through the argument that Erdrich's core theme is the Ojibwe concept of the 'good life'–mino bimaadiziwin–...

  15. Cross section measurements for quasi-elastic neutrino-nucleus scattering with the MINOS near detector

    Energy Technology Data Exchange (ETDEWEB)

    Dorman, Mark Edward [Univ. College London, Bloomsbury (United Kingdom)

    2008-04-01

    The Main Injector Neutrino Oscillation Search (MINOS) is a long baseline neutrino oscillation experiment based at the Fermi National Accelerator Laboratory (FNAL) in Chicago, Illinois. MINOS measures neutrino interactions in two large iron-scintillator tracking/sampling calorimeters; the Near Detector on-site at FNAL and the Far Detector located in the Soudan mine in northern Minnesota. The Near Detector has recorded a large number of neutrino interactions and this high statistics dataset can be used to make precision measurements of neutrino interaction cross sections. The cross section for charged-current quasi-elastic scattering has been measured by a number of previous experiments and these measurements disagree by up to 30%. A method to select a quasi-elastic enriched sample of neutrino interactions in the MINOS Near Detector is presented and a procedure to fit the kinematic distributions of this sample and extract the quasi-elastic cross section is introduced. The accuracy and robustness of the fitting procedure is studied using mock data and finally results from fits to the MINOS Near Detector data are presented.

  16. Cross section measurements for quasi-elastic neutrino-nucleus scattering with the MINOS near detector

    International Nuclear Information System (INIS)

    Dorman, Mark Edward

    2008-01-01

    The Main Injector Neutrino Oscillation Search (MINOS) is a long baseline neutrino oscillation experiment based at the Fermi National Accelerator Laboratory (FNAL) in Chicago, Illinois. MINOS measures neutrino interactions in two large iron-scintillator tracking/sampling calorimeters; the Near Detector on-site at FNAL and the Far Detector located in the Soudan mine in northern Minnesota. The Near Detector has recorded a large number of neutrino interactions and this high statistics dataset can be used to make precision measurements of neutrino interaction cross sections. The cross section for charged-current quasi-elastic scattering has been measured by a number of previous experiments and these measurements disagree by up to 30%. A method to select a quasi-elastic enriched sample of neutrino interactions in the MINOS Near Detector is presented and a procedure to fit the kinematic distributions of this sample and extract the quasi-elastic cross section is introduced. The accuracy and robustness of the fitting procedure is studied using mock data and finally results from fits to the MINOS Near Detector data are presented

  17. Ground-based PTR-MS measurements of reactive organic compounds during the MINOS campaign in Crete, July–August 2001

    Directory of Open Access Journals (Sweden)

    G. Salisbury

    2003-01-01

    Full Text Available This study presents measurements of acetonitrile, benzene, toluene, methanol and acetone made using the proton-transfer-reaction mass spectrometry (PTR-MS technique at the Finokalia ground station in Crete during the Mediterranean INtensive Oxidant Study (MINOS in July-August 2001. Three periods during the campaign with broadly consistent back trajectories are examined in detail. In the first, air was advected from Eastern Europe without significant biomass burning influence (mean acetonitrile mixing ratio 154 pmol/mol. In the second period, the sampled air masses originated in Western Europe, and were advected approximately east-south-east, before turning south-west over the Black Sea and north-western Turkey. The third well-defined period included air masses advected from Eastern Europe passing east and south of/over the Sea of Azov, and showed significant influence by biomass burning (mean acetonitrile mixing ratio 436 pmol/mol, confirmed by satellite pictures. The mean toluene:benzene ratios observed in the three campaign periods described were 0.35, 0.37 and 0.22, respectively; the use of this quantity to determine air mass age is discussed. Methanol and acetone were generally well-correlated both with each other and with carbon monoxide throughout the campaign. Comparison of the acetone and methanol measurements with the MATCH-MPIC model showed that the model underestimated both species by a factor of 4, on average. The correlations between acetone, methanol and CO implied that the relatively high levels of methanol observed during MINOS were largely due to direct biogenic emissions, and also that biogenic sources of acetone were highly significant during MINOS (~35%. This in turn suggests that the model deficit in both species may be due, at least in part, to missing biogenic emissions.

  18. Spontaneous light emission from fibers in MINOS

    International Nuclear Information System (INIS)

    Avvakumov, S.; Barrett, W.L.; Belias, T.; Bower, C.; Erwin, A.; Kordosky, M.; Lang, K.; Lee, R.; Liu, J.; Miller, W.; Mualem, L.; Nichol, R.; Nelson, J.; Pearce, G.; Proga, M.; Rebel, B.; Ruddick, K.; Smith, C.; Thomas, J.; Vahle, P.; Webb, R.

    2005-01-01

    We report on the observation and measurements of unexpected background rates in the MINOS Far Detector. The noise level at the Far Detector is significantly greater than that expected from natural radioactivity and intrinsic photomultiplier dark current. We have conducted a series of additional tests which demonstrate that the excess rate is caused by spontaneous light emission in the wavelength-shifting fibers, which are used to read out signals from scintillator strips. This noise due to fibers exhibits an exponential fall off with time with a decay time constant of the order of 100 days

  19. Search for sterile neutrinos in MINOS and MINOS+ using a two-detector fit

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, P.; et al.

    2017-10-17

    A search for mixing between active neutrinos and light sterile neutrinos has been performed by looking for muon neutrino disappearance in two detectors at baselines of 1.04 km and 735 km, using a combined MINOS and MINOS+ exposure of $16.36\\times10^{20}$ protons-on-target. A simultaneous fit to the charged-current muon neutrino and neutral-current neutrino energy spectra in the two detectors yields no evidence for sterile neutrino mixing using a 3+1 model. The most stringent limit to date is set on the mixing parameter $\\sin^2\\theta_{24}$ for most values of the sterile neutrino mass-splitting $\\Delta m^2_{41} > 10^{-4}$ eV$^2$.

  20. Searching for Sterile Neutrinos with MINOS

    Energy Technology Data Exchange (ETDEWEB)

    Timmons, Ashley [Manchester U.

    2016-01-01

    This document presents the latest results for a 3+1 sterile neutrino search using the $10.56 \\times 10^{20}$ protons-on-target data set taken from 2005 - 2012. By searching for oscillations driven by a large mass splitting, MINOS is sensitive to the existence of sterile neutrinos through any energy dependent deviations using a charged current sample, as well as looking at any relative deficit between neutral current events between the far and near detectors. This document will discuss the novel analysis that enabled a search for sterile neutrinos setting a limit in the previously unexplored regions in the parameter space $\\{\\Delta m^{2}_{41}, \\sin^2\\theta_{24}\\}$. The results presented can be compared to the parameter space suggested by LSND and MiniBooNE and complements other previous experimental searches for sterile neutrinos in the electron neutrino appearance channel.

  1. A measurement of neutrino oscillations with muon neutrinos in the MINOS experiment

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Stephen James [College of William and Mary, Williamsburg, VA (United States)

    2011-05-01

    Experimental evidence has established that neutrino flavor states evolve over time. A neutrino of a particular flavor that travels some distance can be detected in a different neutrino flavor state. The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline experiment that is designed to study this phenomenon, called neutrino oscillations. MINOS is based at Fermilab near Chicago, IL, and consists of two detectors: the Near Detector located at Fermilab, and the Far Detector, which is located in an old iron mine in Soudan, MN. Both detectors are exposed to a beam of muon neutrinos from the NuMI beamline, and MINOS measures the fraction of muon neutrinos that disappear after traveling the 734 km between the two detectors. One can measure the atmospheric neutrino mass splitting and mixing angle by observing the energy-dependence of this muon neutrino disappearance. MINOS has made several prior measurements of these parameters. Here I describe recently-developed techniques used to enhance our sensitivity to the oscillation parameters, and I present the results obtained when they are applied to a dataset that is twice as large as has been previously analyzed. We measure the mass splitting Δm232 = (2.32-0.08+0.12) x 10-3 eV2/c4 and the mixing angle sin2(2θ32) > 0.90 at 90% C.L. These results comprise the world's best measurement of the atmospheric neutrino mass splitting. Alternative disappearance models are also tested. The neutrino decay hypothesis is disfavored at 7.2σ and the neutrino quantum decoherence hypothesis is disfavored at 9.0σ.

  2. Characterization of carbonaceous aerosols during the MINOS campaign in Crete, July–August 2001: a multi-analytical approach

    Directory of Open Access Journals (Sweden)

    J. Sciare

    2003-01-01

    Full Text Available During the major part of the Mediterranean Intensive Oxidant Study (MINOS campaign (summer 2001, Crete Isl., the Marine Boundary Layer (MBL air was influenced by long range transport of biomass burning from the northern and western part of the Black Sea. During this campaign, carbonaceous aerosols were collected on quartz filters at a Free Tropospheric (FT site, and at a MBL site together with size-resolved distribution of aerosols. Three Evolution Gas Analysis (EGA protocols have been tested in order to better characterize the collected aged biomass burning smoke: A 2-step thermal method (Cachier et al., 1989 and a thermo-optical technique using two different temperature programs. The later temperature programs are those used for IMPROVE (Interagency Monitoring of Protected Visual Environments and NIOSH 5040 (National Institute of Occupational Safety and Health. Artifacts were observed using the NIOSH temperature program and identified as interactions between carbon and dust deposited on the filter matrix at high temperature (T>550ºC under the pure helium step of the analysis. During the MINOS campaign, Black Carbon (BC and Organic Carbon (OC mass concentrations were on average respectively 1.19±0.56 and 3.62±1.08 mgC/m3 for the IMPROVE temperature program, and 1.09±0.36 and 3.75±1.24 mgC/m3 for the thermal method. Though these values compare well on average and the agreement between the Total Carbon (TC measurements sample to sample was excellent (slope=1.00, r2=0.93, n=56, important discrepancies were observed in determining BC concentrations from these two methods (average error of 33±22%. BC from the IMPROVE temperature program compared well with non-sea-salt potassium (nss-K pointing out an optical sensitivity to biomass burning. On the other hand, BC from the thermal method showed a better agreement with non-sea-salt sulfate (nss-SO4, considered as a tracer for fossil fuel combustion during the MINOS campaign. The coupling between

  3. Measuring Antineutrino Oscillations with the MINOS Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Justin John [Univ. of Oxford (United Kingdom)

    2008-09-01

    MINOS is a long baseline neutrino oscillation experiment. A manmade beam of predominantly muon neutrinos is detected both 1 km and 735 km from the production point by two functionally identical detectors. A comparison of the energy spectra measured by the two detectors shows the energy-dependent disappearance of muon neutrinos characteristic of oscillations and allows a measurement of the parameters governing the oscillations. This thesis presents work leading to measurements of disappearance in the 6% $\\bar{v}$μ background in that beam. A calibration is developed to correct for time-dependent changes in the responses of both detectors, reducing the corresponding uncertainty on hadronic energy measurements from 1.8% to 0.4% in the near detector and from 0.8% to 0.4% in the far detector. A method of selecting charged current $\\bar{v}$μ events is developed, with purities (efficiencies) of 96.5% (74.4%) at the near detector, and 98.8% (70.9%) at the far detector in the region below 10 GeV reconstructed antineutrino energy. A method of using the measured near detector neutrino energy spectrum to predict that expected at the far detector is discussed, and developed for use in the $\\bar{v}$μ analysis. Sources of systematic uncertainty contributing to the oscillation measurements are discussed. In the far detector, 32 charged current $\\bar{v}$μ events are observed below a reconstructed energy of 30 GeV, compared to an expectation of 47.8 for Δ$\\bar{m}$atm2 = Δ$\\bar{m}$atm2, sin2(2$\\bar{θ}$23) = sin2(2θ23). This deficit, in such a low-statistics sample, makes the result difficult to interpret in the context of an oscillation parameter measurement. Possible sources for the discrepancy are discussed, concluding that considerably more data are required for a definitive solution. Running MINOS with a dedicated $\\bar

  4. Recent results from the MINOS experiment

    International Nuclear Information System (INIS)

    Diwan, Milind

    2009-01-01

    MINOS is an accelerator neutrino oscillation experiment at Fermilab. An intense high energy neutrino beams is produced at Fermilab and sent to a near detector on the Fermilab site and also to a 5 kton far detector 735 km away in the Soudan mine in northern Minnesota. The experiment has now had several years of running with millions of events in the near detector and hundreds of events recorded in the far detector. Here it is reported on the recent results from this experiment which include precise measurement of ∣Δm 2 32 ∣, analysis of neutral current data to limit the component of sterile neutrinos, and the search for ν μ →ν e conversion. The focus will be on the analysis of data for ν μ →ν e conversion. Using data from an exposure of 3.14x10 20 protons on target, we have selected electron type events in both the near and the far detector. The near detector is used to measure the background which is extrapolated to the far detector. It has been found 35 events in the signal region with a background expectation of 27∓5(stat)∓2(Syst). Using this observation it has been set a 90 % C.L. limit of sin 2 2θ 13 cp =0 and normal mass hierarchy. Further analysis is under way to reduce backgrounds and improve sensitivity.

  5. Recent Results from the MINOS Experiment

    International Nuclear Information System (INIS)

    Diwan, M.V.

    2009-01-01

    MINOS is an accelerator neutrino oscillation experiment at Fermilab. An intense high energy neutrino beam is produced at Fermilab and sent to a near detector on the Fermilab site and also to a 5 kTon far detector 735 km away in the Soudan mine in northern Minnesota. The experiment has now had several years of running with millions of events in the near detector and hundreds of events recorded in the far detector. I will report on the recent results from this experiment which include precise measurement of |Δm 2 32 |, analysis of neutral current data to limit the component of sterile neutrinos and the search for ν μ → ν e conversion. The focus will be on the analysis of data for ν μ → ν e conversion. Using data from an exposure of 3.14 x 10 20 protons on target, we have selected electron type events in both the near and the far detector. The near detector is used to measure the background which is extrapolated to the far detector. We have found 35 events in the signal region with a background expectation of 27 ± 5(stat) ± 2(syst). Using this observation we set a 90% C.L. limit of sin 2 2θ 13 cp = 0 and normal mass hierarchy. Further analysis is under way to reduce backgrounds and improve sensitivity.

  6. Electron Neutrino Appearance in the MINOS Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Orchanian, Mhair-armen Hagop [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2012-01-01

    This thesis describes a search for ve appearance in the two-detector long-baseline MINOS neutrino experiment at Fermilab, based on a data set representing an exposure of 8.2×1020 protons on the NuMI target. The analysis detailed herein represents an increase in sensitivity to the θ13 mixing angle of approximately 25% over previous analyses, due to improvements in the event discriminant and fitting technique. Based on our observation, we constrain the value of θ13 further, finding 2 sin2θ 23 sin2θ 13< 0.12(0.20) at the 90% confidence level for δCP = 0 and the normal (inverted) neutrino mass hierarchy. The best-fit value is 2 sin2θ 23 sin2θ 13 = 0.041+0.047 -0.031(0.079+0.071 -0.053) under the same assumptions. We exclude the θ 13 = 0 hypothesis at the 89% confidence level.

  7. Detectors for the MINOS long-baseline neutrino oscillation experiment

    International Nuclear Information System (INIS)

    Ayres, D.S.

    1996-01-01

    The MINOS long-baseline experiment will use an intense neutrino beam, generated by Fermilab''s Main Injector accelerator, and 730 km flight path to search for neutrino oscillations. The 10,000 ton MINOS far detector will utilize toroidally magnetized steel plates interleaved with track chambers to reconstruct event topologies and to measure the energies of the muons, hadrons and electromagnetic showers produced by neutrino interactions. The MINOS collaboration is currently developing three alternative technologies for the track chambers: ''Iarocci'' tubes (operated in either limited streamer or saturated proportional mode), RPC''s (with either glass or ABS plates), and scintillator (either liquid or plastic) with wavelength shifting fiber readout. The technology choice will be made in mid 1997 based on the projected performance and cost of the 32,000 m 2 active detector system

  8. Transport and build-up of tropospheric trace gases during the MINOS campaign: comparision of GOME, in situ aircraft measurements and MATCH-MPIC-data

    Directory of Open Access Journals (Sweden)

    A. Ladstätter-Weißenmayer

    2003-01-01

    Full Text Available The MINOS (Mediterranean INtensive Oxidant Study campaign was an international, multi-platform field campaign to measure long-range transport of air-pollution and aerosols from South East Asia and Europe towards the Mediterranean basin during August 2001. High pollution events were observed during this campaign. For the Mediterranean region enhanced tropospheric nitrogen dioxide (NO2 and formaldehyde (HCHO, which are precursors of tropospheric ozone (O3, were detected by the satellite based GOME (Global Ozone Monitoring Experiment instrument and compared with airborne in situ measurements as well as with the output from the global 3D photochemistry-transport model MATCH-MPIC (Model of Atmospheric Transport and CHemistry - Max Planck Institute for Chemistry. The increase of pollution in that region leads to severe air quality degradation with regional and global implications.

  9. Measurement of the $M_A^{QE}$ parameter using multiple quasi-elastic dominated sub-samples in the minos near detector

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Nathan Samuel [Indiana Univ., Bloomington, IN (United States)

    2011-12-05

    The Main Injector Neutrino Oscillation Search (MINOS) is a two detector, long baseline neutrino oscillation experiment. The MINOS near detector is an ironscintillator tracking/sampling calorimeter and has recorded the world’s largest data set of neutrino interactions in the 0-5 GeV region. This high statistics data set is used to make precision measurements of neutrino interaction cross-sections on iron. The Q2 dependence in charged current quasi-elastic (CCQE) scattering probes the axial and vector structure (form factor) of the nucleon/nuclear target, and nuclear effects in neutrino scattering. Presented here is a study of the MINOS Data that will introduce a method that improves the existing MINOS CCQE analysis. This analysis uses an additional CCQE dominated sub-sample from a different kinematic region to reduce correlations between fit parameters in the existing MINOS CCQE analysis. The measured value of the axial-vector mass is MQE A = 1.312+0.037 -0.038(fit)+0.123 -0.265(syst.) GeV.

  10. Measuring the Disappearance of Muon Neutrinos with the MINOS Detector

    Energy Technology Data Exchange (ETDEWEB)

    Radovic, Alexander [Univ. College London, Bloomsbury (United Kingdom)

    2013-08-01

    MINOS is a long baseline neutrino oscillation experiment. It measures the flux from the predominately muon neutrino NuMI beam first 1 km from beam start and then again 735 km later using a pair of steel scintillator tracking calorimeters. The comparison of measured neutrino energy spectra at our Far Detector with the prediction based on our Near Detector measurement allows for a measurement of the parameters which define neutrino oscillations. This thesis will describe the most recent measurement of muon neutrino disappearance in the NuMI muon neutrino beam using the MINOS experiment.

  11. A Sterile-Neutrino Search with the MINOS Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Philip [Univ. of Oxford (United Kingdom)

    2010-01-01

    The MINOS experiment is a long-baseline neutrino oscillation experiment in the the NuMI beamline at Fermilab, USA. Using a near detector at 1 km distance from the neutrino production target, and a far detector at 735 km from the target, it is designed primarily to measure the disappearance of muon neutrinos. This thesis presents an analysis using MINOS data of the possibility of oscil- lation of the neutrinos in the NuMI beam to a hypothetical sterile flavour, which would have no Standard Model couplings. Such oscillations would result in a deficit in the neutral current interaction rate in the MINOS far detector relative to the expectation derived from the near detector data. The method used to identify neutral current and charged current events in the MINOS detectors is described and a new method of predicting and fitting the far detector spectrum presented, along with the effects of systematic uncertainties on the sterile neutrino oscillation analysis. Using this analysis, the fraction fs of the disappearing neutrinos that go to steriles is constrained to be below 0.15 at the 90% confidence level in the absence of electron neutrino appearance in the NuMI beam. With electron appearance at the CHOOZ limit, fs < 0.41 at 90% C.L.

  12. A Sterile-Neutrino Search with the MINOS Experiment

    International Nuclear Information System (INIS)

    Rodrigues, Philip

    2010-01-01

    The MINOS experiment is a long-baseline neutrino oscillation experiment in the the NuMI beamline at Fermilab, USA. Using a near detector at 1 km distance from the neutrino production target, and a far detector at 735 km from the target, it is designed primarily to measure the disappearance of muon neutrinos. This thesis presents an analysis using MINOS data of the possibility of oscil- lation of the neutrinos in the NuMI beam to a hypothetical sterile flavour, which would have no Standard Model couplings. Such oscillations would result in a deficit in the neutral current interaction rate in the MINOS far detector relative to the expectation derived from the near detector data. The method used to identify neutral current and charged current events in the MINOS detectors is described and a new method of predicting and fitting the far detector spectrum presented, along with the effects of systematic uncertainties on the sterile neutrino oscillation analysis. Using this analysis, the fraction f s of the disappearing neutrinos that go to steriles is constrained to be below 0.15 at the 90% confidence level in the absence of electron neutrino appearance in the NuMI beam. With electron appearance at the CHOOZ limit, f s < 0.41 at 90% C.L.

  13. Characterization of 1600 Hamamatsu 16-anode photomultipliers for the MINOS Far detector

    International Nuclear Information System (INIS)

    Lang, K.; Day, J.; Eilerts, S.; Fuqua, S.; Guillen, A.; Kordosky, M.; Lang, M.; Liu, J.; Opaska, W.; Proga, M.; Vahle, P.; Winbow, A.; Drake, G.; Thomas, J.; Andreopoulos, C.; Saoulidou, N.; Stamoulis, P.; Tzanakos, G.; Zois, M.; Weber, A.; Michael, D.

    2005-01-01

    We are reporting results of the characterization of over 1600 multi-anode R5900-00-M16 photomultipliers manufactured by Hamamatsu Photonics K.K., and installed in the MINOS Far detector. We have conducted extensive tests of the uniformity of gain and collection efficiency of individual anodes, the cross-talk among all 16 channels, the dark noise, and the linearity of response. In our studies we used a blue light-emitting diode to illuminate phototubes through 1.2 mm diameter optical fibers. In this paper, we present summaries of the main characteristics of the tested photomultipliers

  14. Oxidizer Scoping Studies

    Energy Technology Data Exchange (ETDEWEB)

    Chancellor, Christopher John [Los Alamos National Laboratory

    2016-11-07

    The purpose of this report is to present the results of the acceptable knowledge (AK) review of oxidizers present in active waste streams, provide a technical analysis of the oxidizers, and report the results of the scoping study testing. This report will determine the fastest burning oxidizer to be used in the development of a Test Plan for Preparation and Testing of Sorbents Mixed with Oxidizer found in Transuranic Waste (DWT-TP-001). The companion report, DWT-RPT-002, Sorbent Scoping Studies, contains similar information for sorbents identified during the AK review of TRU waste streams. The results of the oxidizer and sorbent scoping studies will be used to inform the QL1 test plan. The QL1 test results will support the development of a basis of knowledge document that will evaluate oxidizing chemicals and sorbents in TRU waste and provide guidance for treatment.

  15. Astroparticle physics with the MINOS Far Detector

    Energy Technology Data Exchange (ETDEWEB)

    Grashorn, Eric William [Univ. of Minnesota, Minneapolis, MN (United States)

    2008-06-01

    Since August 2003, the MINOS Far Detector collected over 67 million underground muons at Soudan MN, USA. As the temperature of the atmosphere changes, the interaction height of incident cosmic rays changes, which affects the production of muons that are seen underground. A four percent peak-to-peak seasonal fl was seen over a period of four years, which was highly correlated to the measured temperature variations of the upper atmosphere over the same period. The coeffi relating changes in the muon rate to changes changes in atmospheric temperature, αT , was found to be: αT = 0.877 ± 0.010 (stat.) ±0.017 (syst.). A new model was developed to describe the observed effect, and is the fi to include the contribution from kaons. This model predicts αT = 0.865 ± 0.015. The fi measurements of charge separated seasonal variations were reported: αT+) = 0.782 ± 0.056 (stat.) ± 0.02 (syst.), αT (µ-) = 0.788 ± 0.066 (stat.) ± 0.02 (syst.). The observed difference between the pion-only temperature coeffi and the kaon-inclusive temperature coeffi allowed a measurement of the atmospheric K/π ratio = 0.21 ± 0.08. A high signifi observation of two muon signals, the shadow of the sun and moon, have been seen. The shadow of the moon was observed at the 5 σ level, and the shadow of the sun was observed at the 4.3 σ level. The angular resolution of the detector was found to be 0.62° using dimuons, and the two dimensional shadowing distribution was used to quantify the absolute pointing of the detector 0.15 ± 0.10 . A cosmic ray point source search was performed, and no statistically signifi source was found. In the absence of a source, 95% fl limits were placed on cosmic ray sources. The minimum fl limit was -16 -2 -1 2.7 × 10 cm s , which is comparable to the previous best limit set by MACRO [1, 2]. Using the 239 Gamma Ray Bursts (GRBs) of the fi Swift catalog a search for space-time coincidence

  16. The magnetized steel and scintillator calorimeters of the MINOS experiment

    Energy Technology Data Exchange (ETDEWEB)

    Michael, : D.G.

    2008-05-01

    The Main Injector Neutrino Oscillation Search (MINOS) experiment uses an accelerator-produced neutrino beam to perform precision measurements of the neutrino oscillation parameters in the 'atmospheric neutrino' sector associated with muon neutrino disappearance. This long-baseline experiment measures neutrino interactions in Fermilab's NuMI neutrino beam with a near detector at Fermilab and again 735 km downstream with a far detector in the Soudan Underground Laboratory in northern Minnesota. The two detectors are magnetized steel-scintillator tracking calorimeters. They are designed to be as similar as possible in order to ensure that differences in detector response have minimal impact on the comparisons of event rates, energy spectra and topologies that are essential to MINOS measurements of oscillation parameters. The design, construction, calibration and performance of the far and near detectors are described in this paper.

  17. Measurement of electron neutrino appearance with the MINOS experiment

    International Nuclear Information System (INIS)

    Boehm, Joshua Adam Alpern

    2009-01-01

    MINOS is a long-baseline two-detector neutrino oscillation experiment that uses a high intensity muon neutrino beam to investigate the phenomena of neutrino oscillations. By measuring the neutrino interactions in a detector near the neutrino source and again 735 km away from the production site, it is possible to probe the parameters governing neutrino oscillation. The majority of the ν μ oscillate to ν τ but a small fraction may oscillate instead to ν e . This thesis presents a measurement of the ν e appearance rate in the MINOS far detector using the first two years of exposure. Methods for constraining the far detector backgrounds using the near detector measurements is discussed and a technique for estimating the uncertainty on the background and signal selection are developed. A 1.6σ excess over the expected background rate is found providing a hint of ν e appearance.

  18. Effects of non-standard interactions in the MINOS experiment

    International Nuclear Information System (INIS)

    Blennow, Mattias; Ohlsson, Tommy; Skrotzki, Julian

    2008-01-01

    We investigate the effects of non-standard interactions on the determination of the neutrino oscillation parameters Δm 31 2 , θ 23 , and θ 13 in the MINOS experiment. We show that adding non-standard interactions to the analysis lead to an extension of the allowed parameter space to larger values of Δm 31 2 and smaller θ 23 , and basically removes all predictability for θ 13 . In addition, we discuss the sensitivities to the non-standard interaction parameters of the MINOS experiment alone. In particular, we examine the degeneracy between θ 13 and the non-standard interaction parameter ε eτ . We find that this degeneracy is responsible for the removal of the θ 13 predictability and that the possible bound on |ε eτ | is competitive with direct bounds only if a more stringent external bound on θ 13 is applied

  19. Zircaloy oxidation studies

    International Nuclear Information System (INIS)

    Prater, J.T.; Beauchamp, R.H.; Saenz, N.T.

    1985-06-01

    The oxidation kinetics of Zircaloy-4 in steam have been determined at 1300-2400 0 C. Growth of the ZrO 2 and α-Zr layers display parabolic behavior over the entire temperature range studied. A discontinuity in the oxidation kinetics at 1510 0 C causes rates to increase above those previously established by the Baker-Just relationship. This increase coincides with the tetragonal-to-cubic phase transformation in ZrO/sub 2-x/. No discontinuity in the oxide growth rate is observed upon melting of Zr(0). The effects of temperature gradients have been taken into account and corrected values representative of near-isothermal conditions have been computed

  20. Search for neutrino oscillations in the MINOS experiment by using quasi-elastic interactions

    Energy Technology Data Exchange (ETDEWEB)

    Piteira, Rodolphe [Univ. Pierre et Marie Curie, Paris (France)

    2005-09-29

    The enthusiasm of the scientific community for studying oscillations of neutrinos is equaled only by the mass of their detectors. The MINOS experiment determines and compares the near spectrum of muonic neutrinos from the NUMI beam to the far one, in order to measure two oscillation parameters: Δm$2\\atop{23}$ and sin2 (2θ23). The spectra are obtained by analyzing the charged current interactions which difficulty lies in identifying the interactions products (e.g. muons). An alternative method identifying the traces of muons, bent by the magnetic field of the detectors, and determining their energies is presented in this manuscript. The sensitivity of the detectors is optimal for the quasi-elastic interactions, for which a selection method is proposed, to study their oscillation. Even though it reduces the statistics, such a study introduces fewer systematic errors, constituting the ideal method on the long range.

  1. Electron Neutrino and Antineutrino Appearance in the MINOS Detector

    Energy Technology Data Exchange (ETDEWEB)

    Schreckenberger, Adam Paul [Univ. of Minnesota, Minneapolis, MN (United States)

    2013-04-01

    The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline neutrino experiment that utilizes a particle beam and two steel-scintillator calorimeters designed to determine the parameters associated with muon neutrino disappearance. Analysis methods developed by the MINOS νe group have facilitated the placement of limits upon the mixing angle associated with νμ → νe oscillations. Since the polarity of the focusing horns can be switched, we can perform a similar analysis with an antineutrino-enriched beam to select electron antineutrino appearance candidates. Using 3.34e20 POT (protons on target) in the antineutrino mode, we exclude θ13 = 0 at the 80% C.L. A joint fit of the 3.34e20 POT antineutrino and 10.6e20 POT neutrino samples excluded θ13 = 0 at the 96% C.L. In addition, the combined data were used to produce exclusions regarding the CP-violating phase.

  2. CPT conservation and atmospheric neutrinos in the MINOS far detector

    International Nuclear Information System (INIS)

    Becker, Bernard Raymond

    2006-01-01

    The MINOS Far Detector is a 5400 ton iron calorimeter located at the Soudan state park in Soudan Minnesota. The MINOS far detector can observe atmospheric neutrinos and separate charge current ν μ and (bar ν) μ interactions by using a 1.4 T magnetic field to identify the charge of the produced muon. The CPT theorem requires that neutrinos and anti-neutrinos oscillate in the same way. In a fiducial exposure of 5.0 kilo-ton years a total of 41 candidate neutrino events are observed with an expectation of 53.1 ± 7.6(system.) ± 7.2(stat.) unoscillated events or 31.6 ± 4.7(system.) ± 5.6(stat.) events with Δm 2 = 2.4 x 10 -3 eV 2 , sin 2 (2θ) = 1.0 as oscillation parameters. These include 28 events which can have there charge identified with high confidence. These 28 events consist of 18 events consistent with being produced by ν μ and 10 events being consistent with being produced by (bar ν) μ . No evidence of CPT violation is observed

  3. CPT conservation and atmospheric neutrinos in the MINOS far detector

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Bernard Raymond [Univ. of Minnesota, Minneapolis, MN (United States)

    2006-02-01

    The MINOS Far Detector is a 5400 ton iron calorimeter located at the Soudan state park in Soudan Minnesota. The MINOS far detector can observe atmospheric neutrinos and separate charge current νμ and $\\bar{v}$μ interactions by using a 1.4 T magnetic field to identify the charge of the produced muon. The CPT theorem requires that neutrinos and anti-neutrinos oscillate in the same way. In a fiducial exposure of 5.0 kilo-ton years a total of 41 candidate neutrino events are observed with an expectation of 53.1 ± 7.6(system.) ± 7.2(stat.) unoscillated events or 31.6 ± 4.7(system.) ± 5.6(stat.) events with Δm2 = 2.4 x 10-3 eV2, sin2(2θ) = 1.0 as oscillation parameters. These include 28 events which can have there charge identified with high confidence. These 28 events consist of 18 events consistent with being produced by νμ and 10 events being consistent with being produced by $\\bar{v}$μ. No evidence of CPT violation is observed.

  4. MINOS: A simplified Pn solver for core calculation

    International Nuclear Information System (INIS)

    Baudron, A.M.; Lautard, J.J.

    2007-01-01

    This paper describes a new generation of the neutronic core solver MINOS resulting from developments done in the DESCARTES project. For performance reasons, the numerical method of the existing MINOS solver in the SAPHYR system has been reused in the new system. It is based on the mixed-dual finite element approximation of the simplified transport equation. We have extended the previous method to the treatment of unstructured geometries composed by quadrilaterals, allowing us to treat geometries where fuel pins are exactly represented. For Cartesian geometries, the solver takes into account assembly discontinuity coefficients in the simplified P n context. The solver has been rewritten in C + + programming language using an object-oriented design. Its general architecture was reconsidered in order to improve its capability of evolution and its maintainability. Moreover, the performance of the previous version has been improved mainly regarding the matrix construction time; this result improves significantly the performance of the solver in the context of industrial application requiring thermal-hydraulic feedback and depletion calculations. (authors)

  5. Measurement of electron neutrino appearance with the MINOS experiment

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Joshua Adam Alpern [Harvard Univ., Cambridge, MA (United States)

    2009-05-01

    MINOS is a long-baseline two-detector neutrino oscillation experiment that uses a high intensity muon neutrino beam to investigate the phenomena of neutrino oscillations. By measuring the neutrino interactions in a detector near the neutrino source and again 735 km away from the production site, it is possible to probe the parameters governing neutrino oscillation. The majority of the vμ oscillate to vτ but a small fraction may oscillate instead to ve. This thesis presents a measurement of the ve appearance rate in the MINOS far detector using the first two years of exposure. Methods for constraining the far detector backgrounds using the near detector measurements is discussed and a technique for estimating the uncertainty on the background and signal selection are developed. A 1.6σ excess over the expected background rate is found providing a hint of ve appearance.

  6. A search for sterile neutrinos at the MINOS experiment

    Energy Technology Data Exchange (ETDEWEB)

    Pittam, Robert Neil [Univ. of Oxford (United Kingdom)

    2010-01-01

    MINOS is a long baseline neutrino oscillation experiment based at the Fermi National Accelerator Laboratory in Illinois, USA. The experiment was designed to study neutrino oscillation phenomena. The vμ beam produced by the NuMI beam facility at FNAL is used along with two functionally identical detectors. The Near Detector at FNAL and a Far Detector 735 km away in the Soudan Underground Laboratory in northern Minnesota. Comparison of the observed spectra of neutrinos at the two detectors provides the evidence for neutrino oscillations. This thesis presents work on the postulated phenomena of sterile neutrinos. Oscillations between active and sterile neutrinos will lead to a deficit in the expected rate of measured Neutral Current interactions at the Far Detector. A technique for selecting Neutral Current events utilizing an Artificial Neural Network is presented with resulting overall efficiency of 91.1% and purity of 66.0%. A method of predicting the expected Charged and Neutral Current energy spectra at the Far Detector given the data recorded at the Near Detector is presented. A model to search for oscillations between sterile and active neutrinos is developed. Sources of systematic uncertainty that can effect the results of the analysis are discussed. The analysis developed is applied to a Standard Model 3 flavour oscillation model as a cross check under the scenarios with and without ve appearance. The oscillation parameters measured by this model are Δm322 = (2.39-0.15+0.23) x 10-3 eV2 and θ23 = 0.727-0.11+0.22 for the no ve appearance result. An analysis of the resulting prediction reveals no evidence for active neutrino disappearance. The analysis is then performed using the 4 flavour neutrino oscillation model developed. Again this is done under the 2 scenarios of ve appearance and no ve appearance

  7. Oxidation Resistant Graphite Studies

    Energy Technology Data Exchange (ETDEWEB)

    W. Windes; R. Smith

    2014-07-01

    The Very High Temperature Reactor (VHTR) Graphite Research and Development Program is investigating doped nuclear graphite grades exhibiting oxidation resistance. During a oxygen ingress accident the oxidation rates of the high temperature graphite core region would be extremely high resulting in significant structural damage to the core. Reducing the oxidation rate of the graphite core material would reduce the structural effects and keep the core integrity intact during any air-ingress accident. Oxidation testing of graphite doped with oxidation resistant material is being conducted to determine the extent of oxidation rate reduction. Nuclear grade graphite doped with varying levels of Boron-Carbide (B4C) was oxidized in air at nominal 740°C at 10/90% (air/He) and 100% air. The oxidation rates of the boronated and unboronated graphite grade were compared. With increasing boron-carbide content (up to 6 vol%) the oxidation rate was observed to have a 20 fold reduction from unboronated graphite. Visual inspection and uniformity of oxidation across the surface of the specimens were conducted. Future work to determine the remaining mechanical strength as well as graphite grades with SiC doped material are discussed.

  8. An optimized oscillation analysis of MINOS beam data

    International Nuclear Information System (INIS)

    Culling, Andrew John

    2007-01-01

    This thesis presents results of the MINOS long baseline neutrino oscillation experiment. Charged Current interactions of ν μ from the NuMI beamline have been recorded in both the Near and Far Detectors between May 2005 and February 2006, corresponding to 1.27 x 10 20 protons being delivered to the NuMI target. Several techniques for improving the sensitivity of an oscillation measurement are discussed and their impact assessed. 378 events are observed in the Far Detector during this period, compared to a prediction of 459 ± 31 events are observed in the Far Detector during this period, compared to a prediction of 459 ± 31 events when the observed Near Detector spectrum is extrapolated to the Far Detector over the 735 km baseline with no oscillations. In addition to this deficit of observed events, there is also evidence for spectral distortion in the Far Detector. A maximum likelihood analysis is used to determine the best fit point and allowed regions in Δm 2 23 and sin 2 2θ 23 parameter space. The best fit values for Δm 2 23 and sin 2 2θ 23 are found to be 2.55 +0.39 -0.24 x 10 -3 eV 2 and > 0.87 (68% CL) respectively

  9. Domain decomposition methods for core calculations using the MINOS solver

    International Nuclear Information System (INIS)

    Guerin, P.; Baudron, A. M.; Lautard, J. J.

    2007-01-01

    Cell by cell homogenized transport calculations of an entire nuclear reactor core are currently too expensive for industrial applications, even if a simplified transport (SPn) approximation is used. In order to take advantage of parallel computers, we propose here two domain decomposition methods using the mixed dual finite element solver MINOS. The first one is a modal synthesis method on overlapping sub-domains: several Eigenmodes solutions of a local problem on each sub-domain are taken as basis functions used for the resolution of the global problem on the whole domain. The second one is an iterative method based on non-overlapping domain decomposition with Robin interface conditions. At each iteration, we solve the problem on each sub-domain with the interface conditions given by the solutions on the close sub-domains estimated at the previous iteration. For these two methods, we give numerical results which demonstrate their accuracy and their efficiency for the diffusion model on realistic 2D and 3D cores. (authors)

  10. Investigation of alternative mechanisms to neutrino oscillations in the MINOS experiment; Investigacao de Mecanismos Alternativos a Oscilacao de Neutrinos no Experimentos MINOS

    Energy Technology Data Exchange (ETDEWEB)

    de Abreu Barbosa Coelho, Joao [Campinas State Univ., Sao Paulo (Brazil)

    2012-01-01

    The neutrino oscillation model is very successful in explaining a large variety of experiments. The model is based on the premise that the neutrinos that interact through the weak force via charged current are not mass eigenstates, but a superposition of them. In general, a quantum superposition is subject to loss of coherence, so that pure states tend toward mixed states. This type of evolution is not possible within the context of isolated quantum systems because the evolution is unitary and, therefore, is invariant under time reversal. By breaking unitarity, an arrow of time is introduced and the characteristic effect for neutrinos is a damping of oscillations. In this thesis, some phenomenological decoherence and decay models are investigated, which could be observed by MINOS, a neutrino oscillation experiment that consists of measuring the neutrino flux produced in a particle accelerator 735 km away. We analyse the disappearance of muon neutrinos in MINOS. Information from other experiments is used to constrain the number of parameters, leaving only one extra parameter in each model. We assume a power law energy dependence of the decoherence parameter. The official MINOS software and simulation are used to obtain the experiment's sensitivities to the effects of unitarity breaking considered.

  11. Search for Sterile Neutrinos with the MINOS Long-Baseline Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Timmons, Ashley Michael [Univ. of Manchester (United Kingdom)

    2016-01-01

    This thesis will present a search for sterile neutrinos using data taken with the MINOS experiment between 2005 and 2012. MINOS is a two-detector on-axis experiment based at Fermilab. The NuMI neutrino beam encounters the MINOS Near Detector 1km downstream of the neutrino-production target before traveling a further 734km through the Earth's crust, to reach the Far Detector located at the Soudan Underground Laboratory in Northern Minnesota. By searching for oscillations driven by a large mass splitting, MINOS is sensitive to the existence of sterile neutrinos through looking for any energy-dependent perturbations using a charged-current sample, as well as looking at any relative deficit in neutral current events between the Far and Near Detectors. This thesis will discuss the novel analysis that enabled a search for sterile neutrinos covering five orders of magnitude in the mass splitting and setting a limit in previously unexplored regions of the parameter space $\\left\\{\\Delta m^{2}_{41},\\sin^2\\theta_{24}\\right\\}$, where a 3+1-flavour phenomenological model was used to extract parameter limits. The results presented in this thesis are sensitive to the sterile neutrino parameter space suggested by the LSND and MiniBooNE experiments.

  12. In vitro activity of DMG-Mino and DMG-DM Dot, two new glycylcyclines, against anaerobic bacteria.

    Science.gov (United States)

    Nord, C E; Lindmark, A; Persson, I

    1993-10-01

    The in vitro activity of DMG-Mino and DMG-DM Dot against 350 anaerobic bacterial strains including anaerobic cocci, Propionibacterium acnes, Clostridium perfringens, Clostridium difficile, Bacteroides fragilis, other Bacteroides species and fusobacteria was determined by the agar dilution method. Their activity was compared with that of minocycline, doxycycline, piperacillin, cefoxitin, imipenem, clindamycin and metronidazole. DMG-Mino and DMG-DM Dot and imipenem were the most active agents tested. DMG-Mino and DMG-DM Dot had in vitro activity superior to that of minocycline and doxycycline.

  13. GC×GC measurements of C7-C11 aromatic and n-alkane hydrocarbons on Crete, in air from Eastern Europe during the MINOS campaign

    Directory of Open Access Journals (Sweden)

    X. Xu

    2003-01-01

    Full Text Available During the Mediterranean Intensive Oxidant Study (MINOS campaign in August 2001 gas-phase organic compounds were measured using comprehensive two-dimensional gas chromatography (GCxGC at the Finokalia ground station, Crete. In this paper, C7-C11 aromatic and n-alkane measurements are presented and interpreted. The mean mixing ratios of the hydrocarbons varied from 1±1 pptv (i-propylbenzene to 43±36 pptv (toluene. The observed mixing ratios showed strong day-to-day variations and generally higher levels during the first half of the campaign. Mean diel profiles showed maxima at local midnight and late morning, and minima in the early morning and evening. Results from analysis using a simplified box model suggest that both the chemical sink (i.e. reaction with OH and the variability of source strengths were the causes of the observed variations in hydrocarbon mixing ratios. The logarithms of hydrocarbon concentrations were negatively correlated with the OH concentrations integral over a day prior to the hydrocarbon measurements. Slopes of the regression lines derived from these correlations for different compounds are compared with literature rate constants for their reactions with OH. The slopes for most compounds agree reasonably well with the literature rate constants. A sequential reaction model has been applied to the interpretation of the relationship between ethylbenzene and two of its potential products, i.e. acetophenone and benzeneacetaldehyde. The model can explain the good correlation observed between [acetophenone]/[ethylbenzene] and [benzeneacetaldehyde]/[ethylbenzene]. The model results and field measurements suggest that the reactivity of benzeneacetaldehyde may lie between those of acetophenone and ethylbenzene and that the ratio between yields of acetophenone and benzeneacetaldehyde may be up to 28:1. Photochemical ages of trace gases sampled at Finokalia during the campaign are estimated using the sequential reaction model and

  14. GC×GC measurements of C7-C11 aromatic and n-alkane hydrocarbons on Crete, in air from Eastern Europe during the MINOS campaign

    Science.gov (United States)

    Xu, X.; Williams, C.; Plass-Dülmer, H.; Berresheim, H.; Salisbury, G.; Lange, L.; Lelieveld, J.

    2003-09-01

    During the Mediterranean Intensive Oxidant Study (MINOS) campaign in August 2001 gas-phase organic compounds were measured using comprehensive two-dimensional gas chromatography (GCxGC) at the Finokalia ground station, Crete. In this paper, C7-C11 aromatic and n-alkane measurements are presented and interpreted. The mean mixing ratios of the hydrocarbons varied from 1±1 pptv (i-propylbenzene) to 43±36 pptv (toluene). The observed mixing ratios showed strong day-to-day variations and generally higher levels during the first half of the campaign. Mean diel profiles showed maxima at local midnight and late morning, and minima in the early morning and evening. Results from analysis using a simplified box model suggest that both the chemical sink (i.e. reaction with OH) and the variability of source strengths were the causes of the observed variations in hydrocarbon mixing ratios. The logarithms of hydrocarbon concentrations were negatively correlated with the OH concentrations integral over a day prior to the hydrocarbon measurements. Slopes of the regression lines derived from these correlations for different compounds are compared with literature rate constants for their reactions with OH. The slopes for most compounds agree reasonably well with the literature rate constants. A sequential reaction model has been applied to the interpretation of the relationship between ethylbenzene and two of its potential products, i.e. acetophenone and benzeneacetaldehyde. The model can explain the good correlation observed between [acetophenone]/[ethylbenzene] and [benzeneacetaldehyde]/[ethylbenzene]. The model results and field measurements suggest that the reactivity of benzeneacetaldehyde may lie between those of acetophenone and ethylbenzene and that the ratio between yields of acetophenone and benzeneacetaldehyde may be up to 28:1. Photochemical ages of trace gases sampled at Finokalia during the campaign are estimated using the sequential reaction model and related data

  15. Measurement of the Muon Neutrino Inclusive Charged Current Cross Section on Iron using the MINOS Detector

    Energy Technology Data Exchange (ETDEWEB)

    Loiacono, Laura Jean [Univ. of Texas, Austin, TX (United States)

    2010-05-01

    The Neutrinos at the Main Injector (NuMI) facility at Fermi National Accelerator Laboratory (FNAL) produces an intense muon neutrino beam used by the Main Injector Neutrino Oscillation Search (MINOS), a neutrino oscillation experiment, and the Main INjector ExpeRiment v-A, (MINERv A), a neutrino interaction experiment. Absolute neutrino cross sections are determined via σv = N vv , where the numerator is the measured number of neutrino interactions in the MINOS Detector and the denominator is the flux of incident neutrinos. Many past neutrino experiments have measured relative cross sections due to a lack of precise measurements of the incident neutrino flux, normalizing to better established reaction processes, such as quasielastic neutrino-nucleon scattering. But recent measurements of neutrino interactions on nuclear targets have brought to light questions about our understanding of nuclear effects in neutrino interactions. In this thesis the vμ inclusive charged current cross section on iron is measured using the MINOS Detector. The MINOS detector consists of alternating planes of steel and scintillator. The MINOS detector is optimized to measure muons produced in charged current vμ interactions. Along with muons, these interactions produce hadronic showers. The neutrino energy is measured from the total energy the particles deposit in the detector. The incident neutrino flux is measured using the muons produced alongside the neutrinos in meson decay. Three ionization chamber monitors located in the downstream portion of the NuMI beamline are used to measure the muon flux and thereby infer the neutrino flux by relation to the underlying pion and kaon meson flux. This thesis describes the muon flux instrumentation in the NuMI beam, its operation over the two year duration of this measurement, and the techniques used to derive the neutrino flux.

  16. Minos as a novel Tc1/mariner-type transposable element for functional genomic analysis in Aspergillus nidulans.

    Science.gov (United States)

    Evangelinos, Minoas; Anagnostopoulos, Gerasimos; Karvela-Kalogeraki, Iliana; Stathopoulou, Panagiota M; Scazzocchio, Claudio; Diallinas, George

    2015-08-01

    Transposons constitute powerful genetic tools for gene inactivation, exon or promoter trapping and genome analyses. The Minos element from Drosophila hydei, a Tc1/mariner-like transposon, has proved as a very efficient tool for heterologous transposition in several metazoa. In filamentous fungi, only a handful of fungal-specific transposable elements have been exploited as genetic tools, with the impala Tc1/mariner element from Fusarium oxysporum being the most successful. Here, we developed a two-component transposition system to manipulate Minos transposition in Aspergillus nidulans (AnMinos). Our system allows direct selection of transposition events based on re-activation of niaD, a gene necessary for growth on nitrate as a nitrogen source. On average, among 10(8) conidiospores, we obtain up to ∼0.8×10(2) transposition events leading to the expected revertant phenotype (niaD(+)), while ∼16% of excision events lead to AnMinos loss. Characterized excision footprints consisted of the four terminal bases of the transposon flanked by the TA target duplication and led to no major DNA rearrangements. AnMinos transposition depends on the presence of its homologous transposase. Its frequency was not significantly affected by temperature, UV irradiation or the transcription status of the original integration locus (niaD). Importantly, transposition is dependent on nkuA, encoding an enzyme essential for non-homologous end joining of DNA in double-strand break repair. AnMinos proved to be an efficient tool for functional analysis as it seems to transpose in different genomic loci positions in all chromosomes, including a high proportion of integration events within or close to genes. We have used Minos to obtain morphological and toxic analogue resistant mutants. Interestingly, among morphological mutants some seem to be due to Minos-elicited over-expression of specific genes, rather than gene inactivation. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Testing CPT conservation using the NuMI neutrino beam with the MINOS experiment

    Energy Technology Data Exchange (ETDEWEB)

    Auty, David John [Univ. of Sussex, Brighton (United Kingdom)

    2010-03-01

    The MINOS experiment was designed to measure neutrino oscillation parameters with muon neutrinos. It achieves this by measuring the neutrino energy spectrum and flavor composition of the man-made NuMI neutrino beam 1km after the beam is formed and again after 735 km. By comparing the two spectra it is possible to measure the oscillation parameters. The NuMI beam is made up of 7.0%$\\bar{v}$μ, which can be separated from the vμ because the MINOS detectors are magnetized. This makes it possible to study $\\bar{v}$μ oscillations separately from those of muon neutrinos, and thereby test CPT invariance in the neutrino sector by determining the $\\bar{v}$μ oscillation parameters and comparing them with those for vμ, although any unknown physics of the antineutrino would appear as a difference in oscillation parameters. Such a test has not been performed with beam $\\bar{v}$μ before. It is also possible to produce an almost pure $\\bar{v}$μ beam by reversing the current through the magnetic focusing horns of the NuMI beamline, thereby focusing negatively, instead of positively charged particles. This thesis describes the analysis of the 7% $\\bar{v}$μ component of the forward horn current NuMI beam. The $\\bar{v}$μ of a data sample of 3.2 x 10{sup 20} protons on target analysis found 42 events, compared to a CPT conserving prediction of 58.3-7.6+7.6(stat.)-3.6+3.6(syst.) events. This corresponds to a 1.9 σ deficit, and a best fit value of Δ$\\bar{m}$322 = 18 x 10-3 eV2 and sin2 2$\\bar{θ}$23 = 0.55. This thesis focuses particularly on the selection of $\\bar{v}$μ events, and investigates possible improvements of the selection algorithm. From this a different selector was chosen, which corroborated the findings of the original selector. The

  18. Systematic Comparison of the MINOS Near and Far Detector Readout Systems

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera, Anatael [Univ. of Oxford (United Kingdom). Queen' s College

    2005-06-22

    The MINOS experiment is a neutrino oscillation baseline experiment intending to use high resolution L/E neutrinos to measure the atmospheric neutrino oscillations parameters to unprecedented precision. Two detectors have been built to realize the measurements, a Near detector, located about 1km downstream from the beam target at the Fermi Laboratory, and a Far detector, located at 736km, at the Soudan Laboratory. The technique relies on the Near detector to measure the un-oscillated neutrino spectrum, while the Far detector measures the neutrino spectrum once oscillated. The comparison between the two measurements is expected to allow MINOS to measure Δm2 beyond 10% precision level. The Near and Far detectors have been built similarly to minimize possible systematic effects. Both detectors have been endowed with different readout systems, as the beam event rates are very different. The MINOS calibration detector (CalDet), installed at CERN, was instrumented with both readout systems such that they can simultaneously measure and characterize the energy deposition (response and event topology) of incident known particle from test-beams. This thesis presents the investigations to quantify the impact of the performance of both readout systems on the MINOS results using the measurements obtained with CalDet. The relative comparison of the responses of both readout systems have been measured to be consistent with being identical within a systematic uncertainty of 0.6%. The event topologies have been found to be negligibly affected. In addition, the performance of the detector simulations have been thoroughly investigated and validated to be in agreement with data within similar level of uncertainties.

  19. Exhaled nitric oxide and urinary EPX levels in infants: a pilot study

    Directory of Open Access Journals (Sweden)

    Olin Anna-Carin

    2011-05-01

    Full Text Available Abstract Background Objective markers of early airway inflammation in infants are not established but are of great interest in a scientific setting. Exhaled nitric oxide (FeNO and urinary eosinophilic protein X (uEPX are a two such interesting markers. Objective To investigate the feasibility of measuring FeNO and uEPX in infants and their mothers and to determine if any relations between these two variables and environmental factors can be seen in a small sample size. This was conducted as a pilot study for the ongoing Swedish Environmental Longitudinal Mother and child Asthma and allergy study (SELMA. Methods Consecutive infants between two and six months old and their mothers at children's health care centres were invited, and 110 mother-infant pairs participated. FeNO and uEPX were analysed in both mothers and infants. FeNO was analyzed in the mothers online by the use of the handheld Niox Mino device and in the infants offline from exhaled air sampled during tidal breathing. A 33-question multiple-choice questionnaire that dealt with symptoms of allergic disease, heredity, and housing characteristics was used. Results FeNO levels were reduced in infants with a history of upper respiratory symptoms during the previous two weeks (p Conclusion The use of uEPX as a marker of early inflammation was not supported. FeNO levels in infants were associated to windowpane condensation. Measuring FeNO by the present method may be an interesting way of evaluating early airway inflammation. In a major population study, however, the method is difficult to use, for practical reasons.

  20. Measuring $\\theta_{13}$ via Muon Neutrino to Electron Neutrino Oscillations in the MINOS Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Toner, Ruth B. [Univ. of Cambridge (United Kingdom). Pembroke College

    2011-01-01

    One of the primary goals in neutrino physics at the present moment is to make a measurement of the neutrino oscillation parameter $\\theta_{13}$. This parameter, in addition to being unknown, could potentially allow for the introduction of CP violation into the lepton sector. The MINOS long-baseline neutrino oscillation experiment has the ability to make a measurement of this parameter, by looking for the oscillation of muon neutrinos to electron neutrinos between a Near and Far Detector over a distance of 735 km. This thesis discusses the development of an analysis framework to search for this oscillation mode. Two major improvements to pre-existing analysis techniques have been implemented by the author. First, a novel particle ID technique based on strip topology, known as the Library Event Matching (LEM) method, is optimized for use in MINOS. Second, a multiple bin likelihood method is developed to fit the data. These two improvements, when combined, increase MINOS' sensitivity to $\\sin^2(2\\theta_{13})$ by 27\\% over previous analyses. This thesis sees a small excess over background in the Far Detector. A Frequentist interpretation of the data rules out $\\theta_{13}=0$ at 91\\%. A Bayesian interpretation of the data is also presented, placing the most stringent upper boundary on the oscillation parameter to date, at $\\sin^2(2\\theta_{13})<0.09(0.015)$ for the Normal (Inverted) Hierarchy and $\\delta_{CP}=0$.

  1. Performance of a new hand-held device for exhaled nitric oxide measurement in adults and children

    Directory of Open Access Journals (Sweden)

    Janson C

    2006-04-01

    Full Text Available Abstract Background Exhaled nitric oxide (NO measurement has been shown to be a valuable tool in the management of patients with asthma. Up to now, most measurements have been done with stationary, chemiluminescence-based NO analysers, which are not suitable for the primary health care setting. A hand-held NO analyser which simplifies the measurement would be of value both in specialized and primary health care. In this study, the performance of a new electrochemical hand-held device for exhaled NO measurements (NIOX MINO was compared with a standard stationary chemiluminescence unit (NIOX. Methods A total of 71 subjects (6–60 years; 36 males, both healthy controls and atopic patients with and without asthma were included. The mean of three approved exhalations (50 ml/s in each device, and the first approved measurement in the hand-held device, were compared with regard to NO readings (Bland-Altman plots, measurement feasibility (success rate with 6 attempts and repeatability (intrasubject SD. Results Success rate was high (≥ 84% in both devices for both adults and children. The subjects represented a FENO range of 8–147 parts per billion (ppb. When comparing the mean of three measurements (n = 61, the median of the intrasubject difference in exhaled NO for the two devices was -1.2 ppb; thus generally the hand-held device gave slightly higher readings. The Bland-Altman plot shows that the 95% limits of agreement were -9.8 and 8.0 ppb. The intrasubject median difference between the NIOX and the first approved measurement in the NIOX MINO was -2.0 ppb, and limits of agreement were -13.2 and 10.2 ppb. The median repeatability for NIOX and NIOX MINO were 1.1 and 1.2 ppb, respectively. Conclusion The hand-held device (NIOX MINO and the stationary system (NIOX are in clinically acceptable agreement both when the mean of three measurements and the first approved measurement (NIOX MINO is used. The hand-held device shows good repeatability, and it

  2. Performance of a new hand-held device for exhaled nitric oxide measurement in adults and children.

    Science.gov (United States)

    Alving, K; Janson, C; Nordvall, L

    2006-04-20

    Exhaled nitric oxide (NO) measurement has been shown to be a valuable tool in the management of patients with asthma. Up to now, most measurements have been done with stationary, chemiluminescence-based NO analysers, which are not suitable for the primary health care setting. A hand-held NO analyser which simplifies the measurement would be of value both in specialized and primary health care. In this study, the performance of a new electrochemical hand-held device for exhaled NO measurements (NIOX MINO) was compared with a standard stationary chemiluminescence unit (NIOX). A total of 71 subjects (6-60 years; 36 males), both healthy controls and atopic patients with and without asthma were included. The mean of three approved exhalations (50 ml/s) in each device, and the first approved measurement in the hand-held device, were compared with regard to NO readings (Bland-Altman plots), measurement feasibility (success rate with 6 attempts) and repeatability (intrasubject SD). Success rate was high (> or = 84%) in both devices for both adults and children. The subjects represented a FENO range of 8-147 parts per billion (ppb). When comparing the mean of three measurements (n = 61), the median of the intrasubject difference in exhaled NO for the two devices was -1.2 ppb; thus generally the hand-held device gave slightly higher readings. The Bland-Altman plot shows that the 95% limits of agreement were -9.8 and 8.0 ppb. The intrasubject median difference between the NIOX and the first approved measurement in the NIOX MINO was -2.0 ppb, and limits of agreement were -13.2 and 10.2 ppb. The median repeatability for NIOX and NIOX MINO were 1.1 and 1.2 ppb, respectively. The hand-held device (NIOX MINO) and the stationary system (NIOX) are in clinically acceptable agreement both when the mean of three measurements and the first approved measurement (NIOX MINO) is used. The hand-held device shows good repeatability, and it can be used successfully on adults and most children

  3. Measurement of Neutrino Oscillation Parameters Using Anti-fiducial Charged Current Events in MINOS

    Energy Technology Data Exchange (ETDEWEB)

    Strait, Matthew Levy [Univ. of Minnesota, Minneapolis, MN (United States)

    2010-09-01

    Abstract The Main Injector Neutrino Oscillation Search (MINOS) obse rves the disappearance of muon neutrinos as they propagate in the long baseline Neutri nos at the Main Injector (NuMI) beam. MINOS consists of two detectors. The near detector sam ples the initial composition of the beam. The far detector, 735 km away, looks for an energy-d ependent deficit in the neutrino spectrum. This energy-dependent deficit is interpreted as q uantum mechanical oscillations be- tween neutrino flavors. A measurement is made of the effective two-neutrino mixing parameters Δ m 2 ≈ Δ m 2 23 and sin 2 2 θ ≈ sin 2 2 θ 23 . The primary MINOS analysis uses charged current events in the fiducial volume of the far detector. This analysis uses the roughly equal-sized sample of events that fails the fiducial cut, consisting of interact ions outside the fiducial region of the detector and in the surrounding rock. These events provide a n independent and complementary measurement, albeit weaker due to incomplete reconstructi on of the events. This analysis reports on an exposure of 7 . 25 × 10 20 protons-on-target. Due to poor energy resolution, the meas urement of sin 2 2 θ is much weaker than established results, but the measuremen t of sin 2 2 θ > 0 . 56 at 90% confidence is consistent with the accepted value. The measur ement of Δ m 2 is much stronger. Assuming sin 2 2 θ = 1 , Δ m 2 = (2 . 20 ± 0 . 18[stat] ± 0 . 14[syst]) × 10 - -3 eV 2 .

  4. An atmospheric muon neutrino disappearance measurement with the MINOS far detector

    Energy Technology Data Exchange (ETDEWEB)

    Gogos, Jeremy Peter [Univ. of Minnesota, Minneapolis, MN (United States)

    2007-12-01

    It is now widely accepted that the Standard Model assumption of massless neutrinos is wrong, due primarily to the observation of solar and atmospheric neutrino flavor oscillations by a small number of convincing experiments. The MINOS Far Detector, capable of observing both the outgoing lepton and associated showering products of a neutrino interaction, provides an excellent opportunity to independently search for an oscillation signature in atmospheric neutrinos. To this end, a MINOS data set from an 883 live day, 13.1 kt-yr exposure collected between July, 2003 and April, 2007 has been analyzed. 105 candidate charged current muon neutrino interactions were observed, with 120.5 ± 1.3 (statistical error only) expected in the absence of oscillation. A maximum likelihood analysis of the observed log(L/E) spectrum shows that the null oscillation hypothesis is excluded at over 96% confidence and that the best fit oscillation parameters are sin223 = 0.95 -0.32 and Δm$2\\atop{23}$ = 0.93$+3.94\\atop{ -0.44}$ x 10-3 eV2. This measurement of oscillation parameters is consistent with the best fit values from the Super-Kamiokande experiment at 68% confidence.

  5. Nanoroses of nickel oxides: Synthesis, electron tomography study, and application in CO oxidation and energy storage

    KAUST Repository

    Fihri, Aziz; Sougrat, Rachid; Baby, Rakhi Raghavan; Rahal, Raed; Cha, Dong Kyu; Hedhili, Mohamed N.; Bouhrara, Mohamed; Alshareef, Husam N.; Polshettiwar, Vivek

    2012-01-01

    Nickel oxide and mixed-metal oxide structures were fabricated by using microwave irradiation in pure water. The nickel oxide self-assembled into unique rose-shaped nanostructures. These nickel oxide roses were studied by performing electron

  6. A Measurement of Electron Neutrino Appearance in the MINOS Experiment After Four Years of Data

    Energy Technology Data Exchange (ETDEWEB)

    Cavanaugh, Steven [Harvard Univ., Cambridge, MA (United States)

    2010-05-01

    This work attempts to measure or set a limit on sin2(2θ13), the parameter which describes vμ → ve oscillations. The MINOS detectors at Fermilab are used to perform a search for the oscillations utilizing a beam of vμ neutrinos created in the NuMI beamline by the collisions of 120 GeV protons with a carbon target. These collisions create π± and K± which are focused with magnetic horns, are allowed to decay, and result in a beam of vμ in the energy range of 1 to 30 GeV. Two functionally identical steel-scintillator calorimetric detectors are utilized to measure the interactions of the generated neutrinos. A detector close to the NuMI beam, located 104 m underground and 1040 m from the target, is used to measure the properties of the neutrino beam, including the flux, composition, and energy spectrum. This information is used in part to generate a predicted spectrum of neutrinos in absence of vμ → ve oscillations in the detector located far from the target, at a distance of 705 m underground and 735.5 km from the target. An excess of predicted ve charged current events in this far detector will be interpreted as vμ → ve oscillations, and a measurement of sin2(2θ13) will be made using a Feldman-Cousins analysis. The measurement of vμ → ve requires the separation of ve candidates from background events. New reconstruction software was developed with a focus on identifying ve candidate events in order to reduce systematic errors. The event parameters measured by this software were used as an input to an artificial neutral network event discriminator. The details of this reconstruction software and the other steps of the analysis necessary to making the measurement will be discussed. This work builds on a previous measurement made with this

  7. Observation of muon intensity variations by season with the MINOS near detector

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, P.; Anghel, I.; Aurisano, A.; Barr, G.; Bishai, M.; Blake, A.; Bock, G. J.; Bogert, D.; Cao, S. V.; Castromonte, C. M.; Childress, S.; Coelho, J. A. B.; Corwin, L.; Cronin-Hennessy, D.; de Jong, J. K.; Devan, A. V.; Devenish, N. E.; Diwan, M. V.; Escobar, C. O.; Evans, J. J.; Falk, E.; Feldman, G. J.; Fields, T. H.; Frohne, M. V.; Gallagher, H. R.; Gomes, R. A.; Goodman, M. C.; Gouffon, P.; Graf, N.; Gran, R.; Grzelak, K.; Habig, A.; Hahn, S. R.; Hartnell, J.; Hatcher, R.; Holin, A.; Huang, J.; Hylen, J.; Irwin, G. M.; Isvan, Z.; James, C.; Jensen, D.; Kafka, T.; Kasahara, S. M. S.; Koizumi, G.; Kordosky, M.; Kreymer, A.; Lang, K.; Ling, J.; Litchfield, P. J.; Lucas, P.; Mann, W. A.; Marshak, M. L.; Mathis, M.; Mayer, N.; McGivern, C.; Medeiros, M. M.; Mehdiyev, R.; Meier, J. R.; Messier, M. D.; Miller, W. H.; Mishra, S. R.; Moed Sher, S.; Moore, C. D.; Mualem, L.; Musser, J.; Naples, D.; Nelson, J. K.; Newman, H. B.; Nichol, R. J.; Nowak, J. A.; O’Connor, J.; Orchanian, M.; Osprey, S.; Pahlka, R. B.; Paley, J.; Patterson, R. B.; Pawloski, G.; Perch, A.; Phan-Budd, S.; Plunkett, R. K.; Poonthottathil, N.; Qiu, X.; Radovic, A.; Rebel, B.; Rosenfeld, C.; Rubin, H. A.; Sanchez, M. C.; Schneps, J.; Schreckenberger, A.; Schreiner, P.; Sharma, R.; Sousa, A.; Tagg, N.; Talaga, R. L.; Thomas, J.; Thomson, M. A.; Tian, X.; Timmons, A.; Tognini, S. C.; Toner, R.; Torretta, D.; Urheim, J.; Vahle, P.; Viren, B.; Weber, A.; Webb, R. C.; White, C.; Whitehead, L.; Whitehead, L. H.; Wojcicki, S. G.; Zwaska, R.

    2014-07-01

    A sample of 1.53$\\times$10$^{9}$ cosmic-ray-induced single muon events has been recorded at 225 meters-water-equivalent using the MINOS Near Detector. The underground muon rate is observed to be highly correlated with the effective atmospheric temperature. The coefficient $\\alpha_{T}$, relating the change in the muon rate to the change in the vertical effective temperature, is determined to be 0.428$\\pm$0.003(stat.)$\\pm$0.059(syst.). An alternative description is provided by the weighted effective temperature, introduced to account for the differences in the temperature profile and muon flux as a function of zenith angle. Using the latter estimation of temperature, the coefficient is determined to be 0.352$\\pm$0.003(stat.)$\\pm$0.046(syst.).

  8. A search for muon neutrino to electron neutrino oscillations in the MINOS Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ochoa Ricoux, Juan Pedro [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2009-01-01

    We perform a search for vμ → ve oscillations, a process which would manifest a nonzero value of the θ13 mixing angle, in the MINOS long-baseline neutrino oscillation experiment. The analysis consists of searching for an excess of ve charged-current candidate events over the predicted backgrounds, made mostly of neutral-current events with high electromagnetic content. A novel technique to select electron neutrino events is developed, which achieves an improved separation between the signal and the backgrounds, and which consequently yields a better reach in θ13. The backgrounds are predicted in the Far Detector from Near Detector measurements. An excess is observed in the Far Detector data over the predicted backgrounds, which is consistent with the background-only hypothesis at 1.2 standard deviations.

  9. A measurement of muon neutrino disappearance with the MINOS detectors and NuMI beam

    Energy Technology Data Exchange (ETDEWEB)

    Ospanov, Rustem [Texas U.

    2008-08-01

    MINOS is a long-baseline two-detector neutrino oscillation experiment that uses a high intensity muon neutrino beam to investigate the phenomena of neutrino oscillations. The neutrino beam is produced by the NuMI facility at Fermilab, Batavia, Illinois, and is observed at near and far detectors placed 734 km apart. The neutrino interactions in the near detector are used to measure the initial muon neutrino fl The vast majority of neutrinos travel through the near detector and Earth matter without interactions. A fraction of muon neutrinos oscillate into other fl vors resulting in the disappearance of muon neutrinos at the far detector. This thesis presents a measurement of the muon neutrino oscillation parameters in the framework of the two-neutrino oscillation hypothesis.

  10. Minos: a SPN solver for core calculation in the DESCARTES system

    International Nuclear Information System (INIS)

    Baudron, A.M.; Lautard, J.J.

    2005-01-01

    This paper describes a new development of a neutronic core solver done in the context of a new generation neutronic reactor computational system, named DESCARTES. For performance reasons, the numerical method of the existing MINOS solver in the SAPHYR system has been reused in the new system. It is based on the mixed dual finite element approximation of the simplified transport equation. The solver takes into account assembly discontinuity coefficients (ADF) in the simplified transport equation (SPN) context. The solver has been rewritten in C++ programming language using an object oriented design. Its general architecture was reconsidered in order to improve its capability of evolution and its maintainability. Moreover, the performances of the old version have been improved mainly regarding the matrix construction time; this result improves significantly the performance of the solver in the context of industrial application requiring thermal hydraulic feedback and depletion calculations. (authors)

  11. Status of Chronic Oxidation Studies of Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mee, Robert W. [Univ. of Tennessee, Knoxville, TN (United States)

    2016-05-01

    Graphite will undergo extremely slow, but continuous oxidation by traces of moisture that will be present, albeit at very low levels, in the helium coolant of HTGR. This chronic oxidation may cause degradation of mechanical strength and thermal properties of graphite components if a porous oxidation layer penetrates deep enough in the bulk of graphite components during the lifetime of the reactor. The current research on graphite chronic oxidation is motivated by the acute need to understand the behavior of each graphite grade during prolonged exposure to high temperature chemical attack by moisture. The goal is to provide the elements needed to develop predictive models for long-time oxidation behavior of graphite components in the cooling helium of HTGR. The tasks derived from this goal are: (1) Oxidation rate measurements in order to determine and validate a comprehensive kinetic model suitable for prediction of intrinsic oxidation rates as a function of temperature and oxidant gas composition; (2) Characterization of effective diffusivity of water vapor in the graphite pore system in order to account for the in-pore transport of moisture; and (3) Development and validation of a predictive model for the penetration depth of the oxidized layer, in order to assess the risk of oxidation caused damage of particular graphite grades after prolonged exposure to the environment of helium coolant in HTGR. The most important and most time consuming of these tasks is the measurement of oxidation rates in accelerated oxidation tests (but still under kinetic control) and the development of a reliable kinetic model. This report summarizes the status of chronic oxidation studies on graphite, and then focuses on model development activities, progress of kinetic measurements, validation of results, and improvement of the kinetic models. Analysis of current and past results obtained with three grades of showed that the classical Langmuir-Hinshelwood model cannot reproduce all

  12. CO oxidation on gold nanoparticles: Theoretical studies

    DEFF Research Database (Denmark)

    Remediakis, Ioannis; Lopez, Nuria; Nørskov, Jens Kehlet

    2005-01-01

    We present a summary of our theoretical results regarding CO oxidation on both oxide-supported and isolated gold nanoparticles. Using Density Functional Theory we have studied the adsorption of molecules and the oxidation reaction of CO on gold clusters. Low-coordinated sites on the gold...... nanoparticles can adsorb small inorganic molecules such as O2 and CO, and the presence of these sites is the key factor for the catalytic properties of supported gold nanoclusters. Other contributions, induced by the presence of the support, can provide parallel channels for the reaction and modulate the final...

  13. Study of nitric oxide catalytic oxidation on manganese oxides-loaded activated carbon at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    You, Fu-Tian [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); University of Chinese Academy of Sciences, Beijing (China); Yu, Guang-Wei, E-mail: gwyu@iue.ac.cn [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Wang, Yin, E-mail: yinwang@iue.ac.cn [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Xing, Zhen-Jiao [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Liu, Xue-Jiao; Li, Jie [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); University of Chinese Academy of Sciences, Beijing (China)

    2017-08-15

    Highlights: • Loading manganese oxides on activated carbon effectively promotes NO oxidation. • NO adsorption-desorption on activated carbon is fundamental to NO oxidation. • A high Mn{sup 4+}/Mn{sup 3+} ratio contributes to NO oxidation by promoting lattice O transfer. - Abstract: Nitric oxide (NO) is an air pollutant that is difficult to remove at low concentration and low temperature. Manganese oxides (MnO{sub x})-loaded activated carbon (MLAC) was prepared by a co-precipitation method and studied as a new catalyst for NO oxidation at low temperature. Characterization of MLAC included X-ray diffraction (XRD), scanning electron microscopy (SEM), N{sub 2} adsorption/desorption and X-ray photoelectron spectroscopy (XPS). Activity tests demonstrated the influence of the amount of MnO{sub x} and the test conditions on the reaction. MLAC with 7.5 wt.% MnO{sub x} (MLAC003) exhibits the highest NO conversion (38.7%) at 1000 ppm NO, 20 vol.% O{sub 2}, room temperature and GHSV ca. 16000 h{sup −1}. The NO conversion of MLAC003 was elevated by 26% compared with that of activated carbon. The results of the MLAC003 activity test under different test conditions demonstrated that NO conversion is also influenced by inlet NO concentration, inlet O{sub 2} concentration, reaction temperature and GHSV. The NO adsorption-desorption process in micropores of activated carbon is fundamental to NO oxidation, which can be controlled by pore structure and reaction temperature. The activity elevation caused by MnO{sub x} loading is assumed to be related to Mn{sup 4+}/Mn{sup 3+} ratio. Finally, a mechanism of NO catalytic oxidation on MLAC based on NO adsorption-desorption and MnO{sub x} lattice O transfer is proposed.

  14. Study of niobium oxidation by photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Durand, C.

    1985-01-01

    The chemical composition of thin oxide layers, grown on clean niobium, in low oxygen pressure, was studied by a surface analysis method: X-ray Photoelectron Spectroscopy. The purpose of this study was to find the best conditions for the building of Nb/Nb oxide/Pb Josephson junctions, and particularly to minimise the interface thickness during the formation of the insulator film (Nb 2 O 5 ) on the metal (Nb). This interface is essentially formed by the monoxide (NbO) and dioxide (NbO 2 ). Nb 3d XPS core level peak positions and area ratios (obtained by the signal decomposition) of the components of the total peak, were used to determine the presence of the different oxidation states II, IV and V, their relative abundance, oxide thicknesses and their depth distribution. All this information was extracted by a special numerical procedure [fr

  15. Observation of seasonal variation of atmospheric multiple-muon events in the MINOS near and far detectors

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, P. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States). et al.

    2015-06-09

    We report the first observation of seasonal modulations in the rates of cosmic ray multiple-muon events at two underground sites, the MINOS Near Detector with an overburden of 225 mwe, and the MINOS Far Detector site at 2100 mwe. Thus, at the deeper site, multiple-muon events with muons separated by more than 8 m exhibit a seasonal rate that peaks during the summer, similar to that of single-muon events. In contrast and unexpectedly, the rate of multiple-muon events with muons separated by less than 5–8 m, and the rate of multiple-muon events in the smaller, shallower Near Detector, exhibit a seasonal rate modulation that peaks in the winter.

  16. Experimental study of oxidative DNA damage

    DEFF Research Database (Denmark)

    Loft, Steffen; Deng, Xin-Sheng; Tuo, Jingsheng

    1998-01-01

    Animal experiments allow the study of oxidative DNA damage in target organs and the elucidation of dose-response relationships of carcinogenic and other harmful chemicals and conditions as well as the study of interactions of several factors. So far the effects of more than 50 different chemical ...

  17. Measuring neutrino oscillation parameters using νμ disappearance in MINOS

    International Nuclear Information System (INIS)

    Backhouse, Christopher James

    2011-01-01

    MINOS is a long-baseline neutrino oscillation experiment. It consists of two large steel-scintillator tracking calorimeters. The near detector is situated at Fermilab, close to the production point of the NuMI muon-neutrino beam. The far detector is 735 km away, 716m underground in the Soudan mine, Northern Minnesota. The primary purpose of the MINOS experiment is to make precise measurements of the 'atmospheric' neutrino oscillation parameters (Δm atm 2 and sin 2 2θ atm ). The oscillation signal consists of an energy-dependent deficit of ν μ interactions in the far detector. The near detector is used to characterize the properties of the beam before oscillations develop. The two-detector design allows many potential sources of systematic error in the far detector to be mitigated by the near detector observations. This thesis describes the details of the ν μ -disappearance analysis, and presents a new technique to estimate the hadronic energy of neutrino interactions. This estimator achieves a significant improvement in the energy resolution of the neutrino spectrum, and in the sensitivity of the neutrino oscillation fit. The systematic uncertainty on the hadronic energy scale was re-evaluated and found to be comparable to that of the energy estimator previously in use. The best-fit oscillation parameters of the ν μ -disappearance analysis, incorporating this new estimator were: Δm 2 = 2.32 -0.08 +0.12 x 10 -3 eV 2 , sin 2 2θ > 0.90 (90% C.L.). A similar analysis, using data from a period of running where the NuMI beam was operated in a configuration producing a predominantly (bar ν) μ beam, yielded somewhat different best-fit parameters Δ(bar m) 2 = (3.36 -0.40 +0.46 (stat.) ± 0.06(syst.)) x 10 -3 eV 2 , sin 2 2(bar θ) = 0.86 -0.12 0 .11 (stat.) ± 0.01(syst.). The tension between these results is intriguing, and additional antineutrino data is currently being taken in order to further investigate this apparent discrepancy.

  18. Kinetic Studies of Catalytic Oxidation of Cyclohexene Using ...

    African Journals Online (AJOL)

    acer

    Kinetic Studies of Catalytic Oxidation of Cyclohexene Using Chromium VI Oxide in. Acetic Acid ... respect to the oxidant using pseudo-order approximation method. .... making the concentration of the cyclohexene in ..... on Titanium Silicate.

  19. Solubility study of Tc(IV) oxides

    International Nuclear Information System (INIS)

    Liu, D.J.; Fan, X.H.

    2005-01-01

    The deep geological disposal of the high level radioactive wastes is expected to be a safer disposal method in most countries. The long-lived fission product 99 Tc is present in large quantities in nuclear wastes and its chemical behavior in aqueous solution is of considerable interest. Under oxidizing conditions technetium exists as the anionic species TcO 4 - whereas under the reducing conditions, expected to exist in a deep geological repository, it is generally predicted that technetium will be present as TcO 2 ·nH 2 O. Hence, the mobility of Tc(IV) in reducing groundwater may be limited by the solubility of TcO 2 ·nH 2 O under these conditions. Due to this fact it is important to investigate the solubility of TcO 2 ·nH 2 O. The solubility determines the release of radionuclides from waste form and is used as a source term in radionuclide migration analysis in performance assessment of radioactive waste repository. Technetium oxide was prepared by reduction of a technetate solution with Sn 2 + . The solubility of Tc(IV) oxide has been determined in simulated groundwater and redistilled water under aerobic and anaerobic conditions. The effects of pH and CO 3 2- concentration of solution on solubility of Tc(IV) oxide were studied. The concentration of total technetium and Tc(IV) species in the solutions were periodically determined by separating the oxidized and reduced technetium species using a solvent extraction procedure and counting the beta activity of the 99 Tc with a liquid scintillation counter. The experimental results show that the rate of oxidation of Tc(IV) in simulated groundwater and redistilled water is about (1.49-1.86) x 10 -9 mol/(L·d) under aerobic conditions, but Tc(IV) in simulated groundwater and redistilled water is not oxidized under anaerobic conditions. Under aerobic or anaerobic conditions the solubility of Tc(IV) oxide in simulated groundwater and redistilled water is equal on the whole after centrifugation or ultrafiltration. The

  20. Defluoridation by Bacteriogenic Iron Oxides: Sorption Studies

    Science.gov (United States)

    Evans, K.; Ferris, F.

    2009-05-01

    At concentrations above 1 mg/L, fluoride in drinking water can lead to dental and skeletal fluorosis, a disease that causes mottling of the teeth, calcification of ligaments, crippling bone deformities and many other physiological disorders that can, ultimately, lead to death. Conservative estimates are that fluorosis afflicts tens of millions of people worldwide. As there is no treatment for fluorosis, prevention is the only means of controlling the disease. While numerous defluoridation techniques have been explored, no single method has been found to be both effective and inexpensive enough to implement widely. Our research began in India, with a large-scale geochemical study of the groundwater in a fluoride-contaminated region of Orissa. Having developed a better understanding of the geochemical relationships that exist between fluoride and other parameters present in an affected area, as well as the complex relationships that arise among those parameters that can impact the presence of fluoride, we began investigating certain remediation scenarios involving iron oxides. A common approach to remediation involves the partitioning of fluoride from groundwater by sorption onto a variety of materials, one of the most effective of which is iron oxide whose surface area acts as a scavenger for fluoride. In the presence of iron oxidizing bacteria, the oxidation rate of iron has been shown to be ˜6 times greater than in their absence; fluoride should, therefore, be removed from an aqueous environment by bacteriogenic iron oxides (BIOS) much more quickly than by abiotic iron oxides. Most recently, sorption studies have been conducted using both BIOS and synthetic hydrous ferric oxides in order to compare the behavior between biotic and abiotic sorbents. These studies have provided sorption isotherms that allow comparison of fluoride removed by sorption to BIOS versus synthetic iron oxides. Sorption affinity constants have also been determined, which allow for the

  1. Neutrino and antineutrino inclusive charged-current cross section measurement with the MINOS near detector

    International Nuclear Information System (INIS)

    Bhattacharya, Debdatta

    2009-01-01

    This thesis presents the measurement of energy dependence of the neutrino-nucleon inclusive charged current cross section on an isoscalar target in the range 3-50 GeV for neutrinos and 5-50 GeV energy range for antineutrinos. The data set was collected with the MINOS Near Detector using the wide band NuMI beam at Fermilab. The size of the charged current sample is 1.94 x 10 6 neutrino events and 1.60 x 10 5 antineutrino events. The flux has been extracted using a low hadronic energy sub-sample of the charged current events. The energy dependence of the cross section is obtained by dividing the charged current sample with the extracted flux. The neutrino and antineutrino cross section exhibits a linear dependence on energy at high energy but shows deviations from linear behavior at low energy. We also present a measurement of the ratio of antineutrino to neutrino inclusive cross section

  2. Antineutrino Oscillations and a Search for Non-standard Interactions with the MINOS

    Energy Technology Data Exchange (ETDEWEB)

    Isvan, Zeynep [Univ. of Pittsburgh, PA (United States)

    2012-01-01

    MINOS searches for neutrino oscillations using the disappearance of muon neutrinos from the NuMI beam at Fermilab between two detectors. The Near Detector, located near the source, measures the beam composition before flavor change occurs. The energy spectrum is measured again at the Far Detector after neutrinos travel a distance. The mixing angle and mass splitting between the second and third mass states are extracted from the energy dependent difference between the spectra at the two detectors. NuMI is able to produce an antineutrino-enhanced beam as well as a neutrino-enhanced beam. Collecting data in antineutrino-mode allows the direct measurement of antineutrino oscillation parameters. From the analysis of the antineutrino mode data we measure $|\\Delta\\bar{m}^{2}_{\\text{atm}}| = 2.62^{+0.31}_{-0.28}\\times10^{-3}\\text{eV}^{2}$ and $\\sin^{2}(2\\bar{\\theta})_{23} = 0.95^{+0.10}_{-0.11}$, which is the most precise measurement of antineutrino oscillation parameters to date. A difference between neutrino and antineutrino oscillation parameters may indicate new physics involving interactions that are not part of the Standard Model, called non-standard interactions, that alter the apparent disappearance probability. Collecting data in neutrino and antineutrino mode independently allows a direct search for non-standard interactions. In this dissertation non-standard interactions are constrained by a combined analysis of neutrino and antineutrino datasets and no evidence of such interactions is found.

  3. Neutrino and antineutrino inclusive charged-current cross section measurement with the MINOS near detector

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Debdatta [Univ. of Pittsburgh, PA (United States)

    2009-01-01

    This thesis presents the measurement of energy dependence of the neutrino-nucleon inclusive charged current cross section on an isoscalar target in the range 3-50 GeV for neutrinos and 5-50 GeV energy range for antineutrinos. The data set was collected with the MINOS Near Detector using the wide band NuMI beam at Fermilab. The size of the charged current sample is 1.94 x 106 neutrino events and 1.60 x 105 antineutrino events. The flux has been extracted using a low hadronic energy sub-sample of the charged current events. The energy dependence of the cross section is obtained by dividing the charged current sample with the extracted flux. The neutrino and antineutrino cross section exhibits a linear dependence on energy at high energy but shows deviations from linear behavior at low energy. We also present a measurement of the ratio of antineutrino to neutrino inclusive cross section.

  4. Laboratory Studies of Hydrocarbon Oxidation Mechanisms

    Science.gov (United States)

    Orlando, J. J.; Tyndall, G. S.; Wallington, T. J.; Burkholder, J. B.; Bertman, S. B.; Chen, W.

    2001-12-01

    The oxidation of hydrocarbon species (alkanes, alkenes, halogenated species, and oxygenates of both natural and anthropogenic origin) in the troposphere leads to the generation of numerous potentially harmful secondary pollutants, such as ozone, organic nitrates and acids, and aerosols. These oxidations proceed via the formation of alkoxy radicals, whose complex chemistry controls the ultimate product distributions obtained. Studies of hydrocarbon oxidation mechanisms are ongoing at NCAR and Ford, using environmental chamber / FTIR absorption systems. The focus of these studies is often on the product distributions obtained at low temperature; these studies not only provide data of direct relevance to the free/upper troposphere, but also allow for a more fundamental understanding of the alkoxy radical chemistry (eg., from the determination of the Arrhenius parameters for unimolecular processes, and the quantification of the extent of the involvement of chemical activation in the alkoxy radical chemistry). In this paper, data will be presented on some or all of the following topics: kinetics/mechanisms for the reactions of OH with the unsaturated species MPAN, acrolein, and crotonaldehyde; the mechanism for the oxidation of ethyl chloride and ethyl bromide; and the mechanism for the reaction of OH with acetone and acetaldehyde at low temperature. The relevance of the data to various aspects of tropospheric chemistry will be discussed.

  5. Oxidation study of Ta–Zr coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yung-I, E-mail: yichen@mail.ntou.edu.tw; Chen, Sin-Min

    2013-02-01

    Refractory metal alloy coatings, such as Mo–Ru and Ta–Ru coatings, have been developed to protect glass molding dies. Forming intermetallic compounds in the coatings inhibits grain growth in high temperature environments when mass producing optical components. After annealing in oxygen containing atmospheres, a surface roughening of the Mo–Ru coatings and a soft oxide layer on the Ta–Ru coatings have been observed in our previous works. Oxidation resistance becomes critical in high-temperature applications. In this study, Ta–Zr coatings were deposited with a Ti interlayer on silicon wafers using direct current magnetron sputtering at 400 °C. The as-deposited Ta–Zr coatings possessed nanocrystallite or amorphous states, depending on the chemical compositions. The annealing treatments were conducted at 600 °C under atmospheres of 50 ppm O{sub 2}–N{sub 2} or 1% O{sub 2}–Ar, respectively. After the annealing treatment, this study investigated variations in crystalline structure, hardness, surface roughness, and chemical composition profiles. Preferential oxidation of Zr in the Ta–Zr coatings was verified using X-ray photoelectron spectroscopy, and the microstructure was observed using transmission electron microscopy. - Highlights: ►The as-deposited Ta-rich Ta–Zr coatings revealed an amorphous structure. ►The Zr-rich coatings presented a crystalline β-Zr phase and an amorphous matrix. ►Zr oxidized preferentially as Ta–Zr coatings annealed at 600 °C. ►The hardness of coatings revealed a parabolic relationship with the oxygen content. ►A protective oxide scale formed on the surface of the crystallized Zr-rich coatings.

  6. Positron Studies of Oxide-Semiconductor Structures

    OpenAIRE

    Uedono , A.; Wei , L.; Kawano , T.; Tanigawa , S.; Suzuki , R.; Ohgaki , H.; Mikado , T.

    1995-01-01

    The annihilation characteristics of positrons in SiO2 films grown on Si substrates were studied by using monoenergetic positron beams. Doppler broadening profiles of the annihilation radiation and lifetime spectra of positrons were measured as a function of incident positron energy for SiO2/Si structures fabricated by various oxidation techniques. From the measurements, it was found that the formation probability of positronium (Ps) atoms in SiO2 films strongly depends on the growth condition...

  7. A proposal for laminated pie mechanical construction of a toroidal magnet for the far detector for the MINOS experiment

    International Nuclear Information System (INIS)

    Fields, T.; Guarino, V.; Petereit, E.; Schoessow, P.; Thompson, K.

    1996-01-01

    This proposal describes an alternative to the reference design for the construction of the toroidal magnet for the detector for the MINOS experiment. This design proposes to construct the steel planes from several steel sheets and laminate them into the required thickness of four centimeters. The 8 meter planes are constructed by cutting all of the steel plates to the same size, which is pie a pie shaped segment of either 30 or 22.5 degrees each. All of the plates in the construction are identical, which is conducive to rapid production and lower cost. The advantages of the proposed laminated construction over the reference design are listed in this paper

  8. Sterile neutrino oscillations in MINOS and hadron production in pC collisions

    Energy Technology Data Exchange (ETDEWEB)

    Tinti, Gemma Maria [Univ. of Oxford (United Kingdom)

    2010-01-01

    MINOS is a long baseline neutrino oscillation experiment, starting with a muon-neutrino beam, for the precise measurement of the atmospheric neutrino oscillation parameters |Δm2| and θ23. The Near Detector measures the neutrino flux and spectra before oscillations. The beam propagates for 735 km to the Far Detector, which measures the depleted spectrum after oscillations. The depletion can be interpreted as vμ → vτ oscillations. Subdominant vμ → ve oscillations may be allowed if the mixing angle θ13 ≠ 0. The two detectors are functionally identical in order to cancel systematic errors when using the Near Detector data to constrain the Far Detector prediction. A crucial part of the analysis is the relative calibration between the two detectors, which is known at the 2% level. A calibration procedure to remove the time and temperature dependence of the detector response using through-going cosmic muons is presented here. Although the two-detector approach reduces the systematic uncertainties related to the neutrino flux, a cross check on the neutrino parent meson ratios is performed in this thesis. The cross sections of mesons produced in proton-carbon interactions from the NA49 experiment have been measured and the results have been compared to the MINOS expectations. A neutrino oscillation analysis allowing mixing to a sterile neutrino is performed, under the assumption that the additional mass splitting is Ο(1 eV2). The analysis uses the energy spectrum of the neutral current interaction products, as neutral current interactions are sensitive to sterile neutrino mixing but not to the active flavour neutrino mixing. The neutrino oscillation parameters have been found to be: |Δm2| = 2.43-0.18+0.21 x 10-3 eV2, θ23 = 40.27°-5.17+14.64, θ24 = 0.00°+5.99 and

  9. Study for the chlorination of zirconium oxide

    International Nuclear Information System (INIS)

    Seo, E.S.M.; Takiishi, H.; Paschoal, J.O.A.; Andreoli, M.

    1990-12-01

    In the development of new ceramic and metallic materials the chlorination process constitutes step in the formation of several intermediate compounds, such as metallic chlorides, used for the production of high, purity raw materials. Chlorination studies with the aim of fabrication special zirconium-base alloys have been carried out at IPEN. Within this program the chlorination technique has been used for zirconium tetrachloride production from zirconium oxide. In this paper some relevant parameters such as: time and temperature of reaction, flow rate of chloride gas and percentage of the reducing agent which influence the efficiency of chlorination of zirconium oxide are evaluated. Thermodynamical aspects about the reactions involved in the process are also presented. (author)

  10. X-ray Absorption Study of Graphene Oxide and Transition Metal Oxide Nanocomposites.

    Science.gov (United States)

    Gandhiraman, Ram P; Nordlund, Dennis; Javier, Cristina; Koehne, Jessica E; Chen, Bin; Meyyappan, M

    2014-08-14

    The surface properties of the electrode materials play a crucial role in determining the performance and efficiency of energy storage devices. Graphene oxide and nanostructures of 3d transition metal oxides were synthesized for construction of electrodes in supercapacitors, and the electronic structure and oxidation states were probed using near-edge X-ray absorption fine structure. Understanding the chemistry of graphene oxide would provide valuable insight into its reactivity and properties as the graphene oxide transformation to reduced-graphene oxide is a key step in the synthesis of the electrode materials. Polarized behavior of the synchrotron X-rays and the angular dependency of the near-edge X-ray absorption fine structures (NEXAFS) have been utilized to study the orientation of the σ and π bonds of the graphene oxide and graphene oxide-metal oxide nanocomposites. The core-level transitions of individual metal oxides and that of the graphene oxide nanocomposite showed that the interaction of graphene oxide with the metal oxide nanostructures has not altered the electronic structure of either of them. As the restoration of the π network is important for good electrical conductivity, the C K edge NEXAFS spectra of reduced graphene oxide nanocomposites confirms the same through increased intensity of the sp 2 -derived unoccupied states π* band. A pronounced angular dependency of the reduced sample and the formation of excitonic peaks confirmed the formation of extended conjugated network.

  11. Kinetic study of the alkaline metals oxidation by dry oxygen

    International Nuclear Information System (INIS)

    Touzain, Ph.

    1967-06-01

    The oxidation of lithium, sodium, potassium, rubidium, cesium and sodium-potassium alloys by dry oxygen is studied at several temperatures and in the oxygen pressure range 40 to 400 mmHg. One distinguishes three different oxidation behaviours (inflammation, ignition and slow combustion) whose zones are precised in function of the temperature. The slow oxidation kinetic laws, the composition of oxides and the motive of oxides colorations are determined. At least, the experimental data are construed theoretically. (author) [fr

  12. Laboratory studies of refractory metal oxide smokes

    International Nuclear Information System (INIS)

    Nuth, J.A.; Nelson, R.N.; Donn, B.

    1989-01-01

    Studies of the properties of refractory metal oxide smokes condensed from a gas containing various combinations of SiH4, Fe(CO)5, Al(CH3)3, TiCl4, O2 and N2O in a hydrogen carrier stream at 500 K greater than T greater than 1500 K were performed. Ultraviolet, visible and infrared spectra of pure, amorphous SiO(x), FeO(x), AlO(x) and TiO(x) smokes are discussed, as well as the spectra of various co-condensed amorphous oxides, such as FE(x)SiO(y) or Fe(x)AlO(y). Preliminary studies of the changes induced in the infrared spectra of iron-containing oxide smokes by vacuum thermal annealing suggest that such materials become increasingly opaque in the near infrared with increased processing: hydration may have the opposite effect. More work on the processing of these materials is required to confirm such a trend: this work is currently in progress. Preliminary studies of the ultraviolet spectra of amorphous Si2O3 and MgSiO(x) smokes revealed no interesting features in the region from 200 to 300 nm. Studies of the ultraviolet spectra of both amorphous, hydrated and annealed SiO(x), TiO(x), AlO(x) and FeO(x) smokes are currently in progress. Finally, data on the oxygen isotopic composition of the smokes produced in the experiments are presented, which indicate that the oxygen becomes isotopically fractionated during grain condensation. Oxygen in the grains is as much as 3 percent per amu lighter than the oxygen in the original gas stream. The authors are currently conducting experiments to understand the mechanism by which fractionation occurs

  13. Using Quasi-Elastic Events to Measure Neutrino Oscillations with MINOS Detectors in the NuMI Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Watabe, Masaki [Texas A & M Univ., College Station, TX (United States)

    2010-05-01

    MINOS (Main Injector Neutrino Oscillation Search) experiment has been designed to search for a change in the avor composition of a beam of muon neutrinos as they travel between the Near Detector at Fermi National Accelerator Laboratory and the Far Detector in the Soudan mine in Minnesota, 735 km from the target. The MINOS oscillation analysis is mainly performed with the charged current (CC) events and sensitive to constrain high- Δm2 values. However, the quasi-elastic (QEL) charged current interaction is dominant in the energy region important to access low- m2 values. For further improvement, the QEL oscillation analysis is performed in this dissertation. A data sample based on a total of 2.50 x 1020 POT is used for this analysis. In summary, 55 QEL-like events are observed at the Far detector while 87.06 ± 13.17 (syst:) events are expected with null oscillation hypothesis. These data are consistent with disappearance via oscillation with m2 = 2:10 0.37 (stat:) ± 0.24 (syst:) eV2 and the maximal mixing angle.

  14. Photoluminescence study in diaminobenzene functionalized graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Abhisek, E-mail: guptaabhisek017@gmail.com, E-mail: cnssks@iacs.res.in; Saha, Shyamal K., E-mail: guptaabhisek017@gmail.com, E-mail: cnssks@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2014-10-15

    Being an excellent electronic material graphene is a very poor candidate for optoelectronic applications. One of the major strategies to develop the optical property in GO is the functionalization of graphene oxide (GO). In the present work GO sheets are functionalized by o-phenylenediamine to achieve diaminobenzene functionalized GO composite (DAB-GO). Formation of DAB-GO composite is further characterized by FTIR, UV, Raman studies. Excellent photoluminescence is observed in DAB-GO composite via passivation of the surface reactive sites by ring-opening amination of epoxides of GO.

  15. Isotopic studies on oxidative methane coupling over samarium oxide

    International Nuclear Information System (INIS)

    Otsuka, Kiyoshi; Inaida, Masakatsu; Wada, Yuji; Komatsu, Takayuki; Morikawa, Akira

    1989-01-01

    The evident kinetic isotope effect was observed for the formations of ethylene and ethane through the oxidative coupling of methane on Sm 2 O 3 , when CH 4 and CD 4 were used as the reactants. Ethanes formed in the reaction of a mixture of CH 4 , CD 4 , and O 2 were C 2 H 6 , C 2 H 3 D 3 , and C 2 D 6 as major products. These results indicate that the rate-determining step of the reaction is abstraction of hydrogen from methane and that ethane is formed through the coupling of methyl intermediate. (author)

  16. Electron microscope study of irradiated beryllium oxide

    International Nuclear Information System (INIS)

    Bisson, A.A.

    1965-06-01

    The beryllium oxide is studied first by fractography, before and after irradiation, using sintered samples. The fractures are examined under different aspects. The higher density sintered samples, with transgranular fractures are the most interesting for a microscopic study. It is possible to mark the difference between the 'pores' left by the sintering process and the 'bubbles' of gases that can be produced by former thermal treatments. After irradiation, the grain boundaries are very much weakened. By annealing, it is possible to observe the evolution of the gases produced by the reaction (n, 2n) and (n. α) and gathered on the grain boundaries. The irradiated beryllium oxide is afterwards studied by transmission. For that, a simple method has been used: little chips of the crushed material are examined. Clusters of point defects produced by neutrons are thus detected in crystals irradiated at the three following doses: 6 x 10 19 , 9 x 10 19 and 2 x 10 20 n f cm -2 at a temperature below 100 deg. C. For the irradiation at 6 x 10 19 n f cm -2 , the defects are merely visible, but at 2 x l0 20 n f cm -2 the crystals an crowded with clusters and the Kikuchi lines have disappeared from the micro-diffraction diagrams. The evolution of the clusters into dislocation loops is studied by a series of annealings. The activation energy (0,37 eV) calculated from the annealing curves suggests that it must be interstitials that condense into dislocation loops. Samples irradiated at high temperatures (650, 900 and 1100 deg. C) are also studied. In those specimens the size of the loops is not the same as the equilibrium size obtained after out of pile annealing at the same temperature. Those former loops are more specifically studied and their Burgers vector is determined by micro-diffraction. (author) [fr

  17. Nanoroses of nickel oxides: Synthesis, electron tomography study, and application in CO oxidation and energy storage

    KAUST Repository

    Fihri, Aziz

    2012-04-11

    Nickel oxide and mixed-metal oxide structures were fabricated by using microwave irradiation in pure water. The nickel oxide self-assembled into unique rose-shaped nanostructures. These nickel oxide roses were studied by performing electron tomography with virtual cross-sections through the particles to understand their morphology from their interior to their surface. These materials exhibited promising performance as nanocatalysts for CO oxidation and in energy storage devices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Kinetic Studies of Catalytic Oxidation of Cyclohexene Using ...

    African Journals Online (AJOL)

    Cyclohexene was oxidized using chromium (VI) oxide (CrO3) in pure acetic acid medium. The products of oxidation were analysed using simple qualitative analysis, IR spectroscopy and Gas chromatography-Mass spectrometry (GC/MS). Kinetics studies were carried out to determine the order of reaction, rate constant and ...

  19. Study of inhibition on lipid oxidation of irradiated pork

    International Nuclear Information System (INIS)

    Ha Yiming

    2006-03-01

    It was studied that the effect factors of irradiation dose, preservation temperature, oxygen content and antioxidant on lipid oxidation of irradiated pork. A mechanism was explained on lipid oxidation of irradiated pork. The results showed that irradiation might aggravate lipid oxidation of pork and that decreased preservation temperature and oxygen content of the packaging, added antioxidant also could effectively inhibit lipid oxidation of irradiated pork. (authors)

  20. Water quality's determination at the Mino River during 1973-1995. Prediction analysis for 2010; Estudio de la calidad del agua del rio Mino durante el periodo 1973-1995. Analisis predictivo a 2010

    Energy Technology Data Exchange (ETDEWEB)

    De las Heras, A.; Medgar, M. J.

    2004-07-01

    The aim of the present work was to determine the water quality at the Mino river (Galicia), which belongs to the North river basin, as well as the problems associated to the contaminant contributions originated due to population changes, industrial development and agriculture and live-sock activities during a 23 years period (1973-1995). Similarly, the prediction of such changes till the year 2010 is also realized. The 26 analyzed parameters were obtained from the Database of the COCA-MOPU (Water Quality Control Web), and they were statistically analyzed by means of the hierarchical cluster analysis, principal complements multi variance analysis and the predictor technique for temporal series. Four different factors were identified: alkalinity, physical water characteristics, salinity and organic burden, with an accumulated variance of 60.2%. The predictive analysis adjusted to the ARIMA model, shows the tendency to rise of variables defining alkalinity, salinity and organic matter, if present conditions are maintained. (Author) 17 refs.

  1. Magneto-optic studies of magnetic oxides

    Energy Technology Data Exchange (ETDEWEB)

    Gehring, Gillian A., E-mail: g.gehring@shef.ac.uk [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Alshammari, Marzook S.; Score, David S.; Neal, James R.; Mokhtari, Abbas; Fox, A. Mark [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom)

    2012-10-15

    A brief review of the use of magneto-optic methods to study magnetic oxides is given. A simple method to obtain the magnetic circular dichroism (MCD) of a thin film on a transparent substrate is described. The method takes full account of multiple reflections in the film and substrate. Examples of the magneto-optic spectra of Co-doped ZnO, Fe{sub 3}O{sub 4}, and GdMnO{sub 3} are given. The Maxwell-Garnett method is used to describe the effects of metallic cobalt inclusions in Co:ZnO samples, and the change of the MCD spectra of Fe{sub 3}O{sub 4} at the Verwey temperature is discussed. Data showing different MCD signals at different energies is presented for GdMnO{sub 3}.

  2. Magneto-optic studies of magnetic oxides

    International Nuclear Information System (INIS)

    Gehring, Gillian A.; Alshammari, Marzook S.; Score, David S.; Neal, James R.; Mokhtari, Abbas; Fox, A. Mark

    2012-01-01

    A brief review of the use of magneto-optic methods to study magnetic oxides is given. A simple method to obtain the magnetic circular dichroism (MCD) of a thin film on a transparent substrate is described. The method takes full account of multiple reflections in the film and substrate. Examples of the magneto-optic spectra of Co-doped ZnO, Fe 3 O 4 , and GdMnO 3 are given. The Maxwell–Garnett method is used to describe the effects of metallic cobalt inclusions in Co:ZnO samples, and the change of the MCD spectra of Fe 3 O 4 at the Verwey temperature is discussed. Data showing different MCD signals at different energies is presented for GdMnO 3 .

  3. A STUDY OF OXIDATIVE STRESS IN DIABETES

    Directory of Open Access Journals (Sweden)

    Babu Rao

    2015-06-01

    Full Text Available Non - enzymatic free radical mediated oxidation of biological molecules, membranes and tissues is associated with a variety of pathological events such as cancer, aging and diabetes mellitus . [1] Increased oxidative stress is seen in both types of diabetes me llitus namely type 1 and type 2, irrespective of duration, complications and treatment. In diabetes mellitus, oxidative stress seems primarily due to both an increased plasma free radical concentration and a sharp decline in antioxidant defences . [1] Among the causes of enhanced free radical production, hyperglycemia and hyper insulinemia seem to play a major role , [2,3] Hyperglycemia is the more easily modifiable factor among the two and good glycemic control can reduce the oxidative stress. Controversy pers ists regarding the other possible mechanisms of increased oxidative stress in diabetes and whether oxidative stress normalizes with adequate metabolic control alone. The role of oxidative stress and diabetic complications has been extensively investigated. Oxidative stress has been suggested to be involved in the genesis of both macro and micro angiopathy [4,5] Prospective trials are now underway addressing the controversial issues of possible role of pharmacological antioxidants in preventing or at least de laying the onset of diabetic complications.

  4. Observation in the MINOS far detector of the shadowing of cosmic rays by the sun and moon

    International Nuclear Information System (INIS)

    2010-01-01

    The shadowing of cosmic ray primaries by the the moon and sun was observed by the MINOS far detector at a depth of 2070 mwe using 83.54 million cosmic ray muons accumulated over 1857.91 live-days. The shadow of the moon was detected at the 5.6 σ level and the shadow of the sun at the 3.8 σ level using a log-likelihood search in celestial coordinates. The moon shadow was used to quantify the absolute astrophysical pointing of the detector to be 0.17 ± 0.12 o . Hints of Interplanetary Magnetic Field effects were observed in both the sun and moon shadow.

  5. Oxidation under electron bombardment. A tool for studying the initial states of silicon oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Carriere, B.; Deville, J.P.; El Maachi, A.

    1987-06-01

    The exciting beam of an Auger electron spectrometer has been used to monitor the oxidation of silicon single crystals at room temperature and very low pressures of oxygen (approx. 10/sup -7/ Torr). This process allows us to build ultra-thin layers of silica on silicon (down to 30 A) but it is mostly used to investigate the mechanisms of the initial stages of oxidation. Auger spectra recorded continuously during the oxidation process provide information on (1) the nature of the silicon-oxygen chemical bonds which are interpreted through fine structure in the Auger peak, and (2) the kinetics of oxide formation which are deduced from curves of Auger signal versus time. An account is given of the contribution of these Auger studies to the description of the intermediate oxide layer during the reaction between silicon and oxygen and the influence of surface structural disorder, induced mainly by argon-ion bombardment, is discussed in terms of reactivity and oxide coverage.

  6. Electrical impedance studies of uranium oxide

    International Nuclear Information System (INIS)

    Hampton, R.N.

    1986-11-01

    The thesis presents data on the electrical properties of uranium oxide at temperatures from 1700K to 4.2K, and pressures between 25 K bar and 70 K bar. The impedance data were analysed using the technique of complex plane representation to establish the conductivity and dielectric constant of uranium dioxide. The thermophysical data were compared with previously reported experimental and theoretical work on uranium dioxide and other fluorite structured oxides. (U.K.)

  7. A mechanistic study on the oxidative coupling of methane over lithium doped magnesium oxide catalysts

    NARCIS (Netherlands)

    Geerts, J.W.M.H.; Kasteren, van J.M.N.; Wiele, van der K.; Imarisio, G.; Frias, M.; Berntgen, J.M.

    1988-01-01

    To elucidate the importance of various reaction steps in the oxidative convers ion of methane, experiments were carried out with three reaction products: ethane, ethylene and carbon monoxide. These products were studied seperately, in oxidation experiments with and without a catalyst. Moreover , the

  8. Tritium oxidation and exchange: preliminary studies

    International Nuclear Information System (INIS)

    Phillips, J.E.; Easterly, C.E.

    1978-05-01

    The radiological hazard resulting from an exposure to either tritium oxide or tritium gas is discussed and the factors contributing to the hazard are presented. From the discussion it appears that an exposure to tritium oxide vapor is 10 4 to 10 5 times more hazardous than exposure to tritium gas. Present and future sources of tritium are briefly considered and indicate that most of the tritium has been and is being released as tritium oxide. The likelihood of gaseous releases, however, is expected to increase in the future, calling to task the present general release assumption that 100% of all tritium released is as oxide. Accurate evaluation of the hazards from a gaseous release will require a knowledge of the conversion rate of tritium gas to tritium oxide. An experiment for determining the conversion rate of tritium gas to tritium oxide is presented along with some preliminary data. The conversion rates obtained for low initial concentrations (10 -4 to 10 -1 mCi/ml) indicate the conversion may proceed more rapidly than would be expected from an extrapolation of previous data taken at higher concentrations

  9. Study of transition metal oxides by photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Rao, C.N.R.; Sarma, D.D.; Vasudevan, S.; Hegde, M.S.

    1979-01-01

    Systematics in the X-ray photoelectron spectra (X.p.e.s.) of Ti, V, Cr, Mn and Nb oxides with the metal ion in different oxidation states as well as of related series of mono-, sesqui- and di-oxides of the first row of transition metals have been investigated in detail. Core level binding energies, spin-orbit splittings and exchange splittings are found to exhibit interesting variations with the oxidation state of the metal or the nuclear charge. The 3d binding energies of the monoxides show a proportionality to Goodenough's (R - RC). Other aspects of interest in the study are the satellite structure and final state effects in the X.p.e.s. of the oxides, and identification of different valence states in oxides of the general formulae Mn02n-1 and M304. The nature of changes in the 3d bands of oxides undergoing metal-insulator transitions is also indicated. (author)

  10. Extraction separation studies of uranium(VI) by amine oxides

    International Nuclear Information System (INIS)

    Ejaz, M.

    1975-01-01

    The extraction of uranium(VI) by two amine oxides, 4-(5-nonyl)pyridine oxide and trioctylamine oxide has been studied. The extraction behavior of these two N-oxides is compared. The dependence of extraction on the type of amine oxide and acid, nature of organic diluent, and amine oxide concentration has been investigated. The influence of the concentration of the metal and salting-out agents is described. The possible mechanism of extraction is discussed in the light of the results of extraction isotherms, loading radiodata, and log-log plots of amine oxide concentration vs distribution ratio. The separation factors for a number of metal ions are reported, and the separation of uranium from some fission elements has also been achieved

  11. ESR study into mechanism of heterogeneous-catalytic oxidation on oxides

    Energy Technology Data Exchange (ETDEWEB)

    Topchieva, K V; Loginov, A Yu; Kostikov, S V [Moskovskij Gosudarstvennyj Univ. (USSR)

    1977-12-11

    The role of radical particles in heterogeneous-catalytic oxidation of H/sub 2/; CO; SO/sub 2/; NH/sub 3/; C/sub 3/H/sub 6/ on the rare earth oxides (yttrium, lanthanum, magnesium and scandium oxides) and alkaline earth metal oxides was studied by the ESR method. The conclusion was made about the great reactivity of the peroxide structures O/sub 2//sup -/ in the oxidation catalysis in comparison to other formulas of chemisorption oxigen on oxides. The kinetic investigations are chemisorption oxigen on oxides. The kinetic investigations are carried out on the change of the concentration of paramagnetic particles O/sub 2/ during the catalysis. On the basis of the received data the conclusion is made about the reaction process of catalytic oxidation on rare and alkaline-earth oxides according to radical-chain mechanism with the formation of radical particles O/sub 2//sup -/, CO/sub 3//sup -/, SO/sub 4//sup -/, CO/sub 2//sup -/ as interediate products.

  12. Oxide surfaces and metal/oxide interfaces studied by grazing incidence X-ray scattering

    Science.gov (United States)

    Renaud, Gilles

    important physical properties such as superconductivity or magnetism is also briefly reviewed. The strengths and limitations of the technique, such as the need for single crystals and surfaces of high crystalline quality are discussed. Finally, an outlook of future prospects in the field is given, such as the study of more complex oxide surfaces, vicinal surfaces, reactive metal/oxide interfaces, metal oxidation processes, the use of surfactants to promote wetting of a metal deposited on an oxide surface or the study of oxide/liquid interfaces in a non-UHV environment.

  13. Study of the oxidation behavior of zirconoium and its alloys

    International Nuclear Information System (INIS)

    Costa, I.

    1985-01-01

    The oxidation behavior of zirconium, zircaloy-4 and Zr-2,5% Nb alloy, as well as the influence of temperature, oxidising atmosphere, metal composition, heat treatment, surface treatment and specimen size on the oxidation of these materials in the temperature range 350 - 900 0 C and at atmospheric pressure have been studied with the aid of thermogravimetry. The results indicate that oxidation rate increases with temperature and the rate of oxidation of the zirconium alloys was appreciable beyond 600 0 C. At temperature higher than 500 0 C, the oxidation curves of the zirconium alloys revealed a rate transition, the kinetics after transition being either mixed parabolic and linear or linear. The transition produced an alteration in oxide characteristics, from being dark and adherent and protective, to white or grey and revealing at times cracks and scaling. The oxidation atmospheres were oxygen and air, and the results showed that the extent of oxidation in air was higher than that in oxygen. Among the metals, zirconium showed a low degree of oxidation, and the alloy Zr-2,5% Nb the lowest resistance to oxidation. Specimens heat treated in the α-phase showed the highest resistance to oxidation, and those heat treated in the β-phase the lowest. Surface treatments in aqueous solutions containing a high concentration of the fluoride ion, left behind fluorates on the surface and increased the oxidation rates of zirconium and zircaloy-4. Specimens with a high proportion of corners in relation to the total area, showed a high extent of oxidation giving rise to cracks in the oxide at the corners. (Author) [pt

  14. Study of internal oxidation kinetics of molybdenum base alloys

    International Nuclear Information System (INIS)

    Krushinskij, Yu.Yu.; Belyakov, B.G.; Belomyttsev, M.Yu.

    1989-01-01

    Metallographic and microdurometric method as well as new technique were used to study kinetics of internal oxidation (IO). It is shown that study of IO kinetics on the base of metallographic measurements of layers depth is not correct because it is related with insufficient sensitivity of the method. IO kinetics under conditions of formation of molybdenum oxide layer on saturated material surface as well as IO of alloy with high carbon content were investigated. Oxide film formation does not affect the IO kinetics; decarburization observed along with oxidation increases the apparent activation energy and K exponent on time dependence of diffusion layer depth

  15. Study of film graphene/graphene oxide obtained by partial reduction chemical of oxide graphite

    International Nuclear Information System (INIS)

    Gascho, J.L.S.; Costa, S.F.; Hoepfner, J.C.; Pezzin, S.H.

    2014-01-01

    This study investigated the morphology of graphene/graphene oxide film obtained by partial chemical reduction of graphite oxide (OG) as well as its resistance to solvents. Films of graphene/graphene oxide are great candidates for replacement of indium oxide doped with tin (ITO) in photoelectric devices. The OG was obtained from natural graphite, by Hummer's method modified, and its reduction is made by using sodium borohydride. Infrared spectroscopy analysis of Fourier transform (FTIR), Xray diffraction (XRD) and scanning electron microscopy, high-resolution (SEM/FEG) for the characterization of graphene/graphene oxide film obtained were performed. This film proved to be resilient, not dispersing in any of the various tested solvents (such as ethanol, acetone and THF), even under tip sonication, this resistance being an important property for the applications. Furthermore, the film had a morphology similar to that obtained by other preparation methods.(author)

  16. Studies on O/M ratio determination in uranium oxide, plutonium oxide and uranium-plutonium mixed oxide

    International Nuclear Information System (INIS)

    Sampath, S.; Chawla, K.L.

    1975-01-01

    Thermogravimetric studies were carried out in unsintered and sintered samples of uranium oxide, plutonium oxide and uranium-plutonium mixed oxide under different atmospheric conditions (air, argon and moist argon/hydrogen). Moisture loss was found to occur below 200 0 C for uranium dioxide samples, upto 700 0 C for sintered plutonium dioxide and negligible for sintered samples. The O/M ratios for non-stoichiometric uranium dioxide (sintered and unsintered), plutonium dioxide and mixed uranium and plutonium oxides (sintered) could be obtained with a precision of +- 0.002. Two reference states UOsub(2.000) and UOsub(2.656) were obtained for uranium dioxide and the reference state MOsub(2.000) was used for other cases. For unsintered plutonium dioxide samples, accurate O/M ratios could not be obtained of overlap of moisture loss with oxygen loss/gain. (author)

  17. The study of the oxidation of the natural flavonol fisetin confirmed quercetin oxidation mechanism

    International Nuclear Information System (INIS)

    Ramešová, Šárka; Sokolová, Romana; Degano, Ilaria

    2015-01-01

    Highlights: • The oxidation mechanisms of fisetin and quercetin were compared. • The oxidation product of fisetin was identified even if it was not stable. • A benzofuranon derivative is the common oxidation product of flavonols. • Fisetin decomposes in solution during minutes handled in the presence of air. - Abstract: Oxidation of the bioactive flavonoid fisetin was studied under inert atmosphere and under ambient conditions. The presence of fast subsequent chemical reactions following the electron transfer was supported by in situ spectroelectrochemistry and identification of products by HPLC-DAD and HPLC–ESI-MS/MS. In the absence of oxygen, 2,6-dihydroxy-2-(3′,4′-dihydroxybenzoyl)-benzofuran-3(2H)-one was identified as the only oxidation product of fisetin. This product was found also as the main oxidation product in the presence of oxygen. The oxidation pathway leading to formation of a benzofuranone derivative can be considered as common for flavonols containing C2-C3 double bond, C3-OH group and dihydroxy-substituted phenyl moiety in its structure. This product was not stable and decomposed further even in contact with oxygen coming from eluents during chromatography. Two oxidation pathways occur under ambient conditions. DFT calculations support the result.

  18. Mechanistic Study of Monodisperse Iron Oxide Nanocrystals ...

    African Journals Online (AJOL)

    To gain better insight into the formation of iron oxide nanocrystals from the solution phase thermal decomposition of iron (III) oleate complex, different reaction conditions including time, heating ramp, as well as concentrations of iron oleate precursor and oleic acid ligand were systematically varied and the resulting ...

  19. Electrochemical studies on vanadium oxides, 9

    International Nuclear Information System (INIS)

    Miura, Takashi; Yamamoto, Masahiro; Takahashi, Hirobumi; Kishi, Tomiya; Nagai, Takashi

    1979-01-01

    The mechanism of the anodic oxidation of various organic compounds-including methanol, formaldehyde, formic acid, ethanol, acetaldehyde and acetic acid-at illuminated vanadium pentoxide (V 2 O 5 ) single crystal electrodes were investigated in aqueous solutions of an H 2 SO 4 -K 2 SO 4 system of about pH 2, in which oxygen evolution from water molecules had previously been confirmed to occur with a current efficiency of about 100%. It was shown that all the organics were oxidized by the so called hole-current doubling mechanism, and that the oxygen evolution reaction, which competed with the above oxidation reaction at the hole-capturing step from the valence band of the electrode, proceeded by the simple hole-capturing mechanism, not followed by an electron injection step into the conduction band. Furthermore, it is considered that chloride ions added to the electrolytes tended to hinder hole-current doubling oxidation owing to their reactivity with the holes at the illuminated V 2 O 5 electrodes. (author)

  20. A microstuctural study on accelerated zirconium alloy oxidation

    International Nuclear Information System (INIS)

    Sohn, Seung Bum; Oh, Seung Jun; Jang, Jung Nam; Kim, Yong Soo; Jung, Yong Hwan; Baek, Jong Hyuk; Park, Jung Yong

    2005-01-01

    It has been reported that the effect of thermal redistribution of hydrides across the zirconium metaloxide interface, coupled with thermal feedback on the metal-oxide interface, is a dominating factor in the accelerated oxidation in zirconium alloys cladding PWR fuel. Basically this influence determines characteristic of oxide layer. Influence estimation for corrosion oxide layer due to hydrogen / hydride carried out because of investigation on the kinetic on accelerated oxidation due to hydride precipitation was preceded. Generally, it is known that ZrO 2 tetragonal layer structures play an important role as a barrier layer. So analysing the ZrO 2 monoclinic and tetragonal structure distribution is our main aim. Especially, this study focused on the hydride effects. In other words, the difference of crystal structure distribution between pre-hydrided and without hydrided specimen is just expected results. Experimental results of microstructure at zirconium metal-oxide interface through TEM and EBSD analysis was confirmed

  1. Studies of physicochemical properties of graphite oxide and thermally exfoliated/reduced graphene oxide

    Directory of Open Access Journals (Sweden)

    Drewniak Sabina Elżbieta

    2015-12-01

    Full Text Available The aim of the experimental research studies was to determine some electrical properties of graphite oxide and thermally exfoliated/reduced graphene oxide. The authors tried to interpret the obtained physicochemical results. For that purpose, both resistance measurements and investigation studies were carried out in order to characterize the samples. The resistance was measured at various temperatures in the course of composition changes of gas atmospheres (which surround the samples. The studies were also supported by such methods as: scanning electron microscopy (SEM, Raman spectroscopy (RS, atomic force microscopy (AFM and thermogravimetry (TG. Moreover, during the experiments also the elemental analyses (EA of the tested samples (graphite oxide and thermally exfoliated/reduced graphene oxide were performed.

  2. XPS studies of the oxide formed on pure Ti

    International Nuclear Information System (INIS)

    Cremery, P.; David, D.; Beranger, G.; Oviedo, C.; Garcia, E.A.

    1980-01-01

    The XPS technique was used to study titanium samples oxidized at 200 ton of pure oxigen at different times and temperatures with the aim of producing variable oxide thicknesses. The thicknesses of different oxigen layers were determined by the nuclear reaction O 16 (d,p) O 17 *. (author) [pt

  3. Studies of Deactivation of Methanol to Formaldehyde Selective Oxidation Catalyst

    DEFF Research Database (Denmark)

    Raun, Kristian Viegaard; Schumann, Max; Høj, Martin

    This work presents a study of the deactivation behavior of Fe-Mo oxide catalyst during selective oxidation of methanol to formaldehyde in a period of 5 days. The structural changes in the catalyst have been investigated in situ for the initial 10 h by Raman spectroscopy, and the structure after 5...

  4. Study of bixin oxidation by ionizing irradiation

    International Nuclear Information System (INIS)

    Fonseca, Thais N.; Teixeira, Paula S.; Moura, Eduardo de; Geraldo, Áurea Beatriz C.

    2017-01-01

    Brazil is the world's largest producer of anatto, followed by Kenya and Peru. The fruit of the annatto tree is constituted by a capsule containing external spines and internal seeds with reddish coloration, providing a natural pigment which is environmentally efficient, being able to replace synthetic pigments and dyes. The active substance of the pigment is Bixin, which is a type of carotenoid which constitutes a greater percentage of pigment in these seeds and has a lipo soluble character. Bixin reacts with NaOH in a saponification reaction giving norbixin, which is water soluble. It is known that the destination of the dye extracted from the fruit is intended for industry, especially the food industry. The culture of annatto tree brings prospects of development in agricultural programs for medium and small producers, which are able to use decadent areas of other crops. In addition to the food sector, new applications for the pigment helps the development of family farming. The pigment extracted from annatto undergoes a natural oxidation; this work aims to evaluate this phenomenon and also the oxidation of the pigment after the irradiation process. This work also evaluates of the how the oxidation process is affected by irradiation and the modifications introduced to irradiated pigments. Irradiated and nonirradiated samples were characterized by thermogravimetry, UV-vis spectrophotometry and infrared spectroscopy (FTIR). The results are then discussed. (author)

  5. Ion irradiation studies of oxide ceramics

    International Nuclear Information System (INIS)

    Zinkle, S.J.

    1988-01-01

    This paper presents the initial results of an investigation of the depth-dependent microstructures of three oxide ceramics following ion implantation to moderate doses. The implantations were performed using ion species that occur as cations in the target material; for example, Mg + ions were used for MgO and MgAl 2 O 4 (spinel) irradiations. This minimized chemical effects associated with the implantation and allowed a more direct evaluation to be made of the effects of implanted ions on the microstructure. 11 refs., 14 figs

  6. Comparative study of synthesis and reduction methods for graphene oxide

    KAUST Repository

    Alazmi, Amira; Rasul, Shahid; Patole, Shashikant P.; Da Costa, Pedro M. F. J.

    2016-01-01

    Graphene oxide (GO) and reduced graphene oxide (rGO) have congregated much interest as promising active materials for a variety of applications such as electrodes for supercapacitors. Yet, partially given the absence of comparative studies in synthesis methodologies, a lack of understanding persists on how to best tailor these materials. In this work, the effect of using different graphene oxidation-reduction strategies in the structure and chemistry of rGOs is systematically discussed. Two of the most popular oxidation routes in the literature were used to obtain GO. Subsequently, two sets of rGO powders were synthesised employing three different reduction routes, totalling six separate products. It is shown that the extension of the structural rearrangement in rGOs is not just dependent on the reduction step but also on the approach followed for the initial graphite oxidation.

  7. Comparative study of synthesis and reduction methods for graphene oxide

    KAUST Repository

    Alazmi, Amira

    2016-05-14

    Graphene oxide (GO) and reduced graphene oxide (rGO) have congregated much interest as promising active materials for a variety of applications such as electrodes for supercapacitors. Yet, partially given the absence of comparative studies in synthesis methodologies, a lack of understanding persists on how to best tailor these materials. In this work, the effect of using different graphene oxidation-reduction strategies in the structure and chemistry of rGOs is systematically discussed. Two of the most popular oxidation routes in the literature were used to obtain GO. Subsequently, two sets of rGO powders were synthesised employing three different reduction routes, totalling six separate products. It is shown that the extension of the structural rearrangement in rGOs is not just dependent on the reduction step but also on the approach followed for the initial graphite oxidation.

  8. Oxidative desulphurization study of gasoline and kerosene. Role of some organic and inorganic oxidants

    Energy Technology Data Exchange (ETDEWEB)

    Shakirullah, M.; Ahmad, Waqas; Ahmad, Imtiaz; Ishaq, M.

    2010-11-15

    Desulphurization of gasoline and kerosene was carried out using organic and inorganic oxidants. Among the organic oxidants used were hydrogen peroxide in combination with acetic acid, formic acid, benzoic acid and butyric acid, while inorganic oxidants used included potassium permanganate and sodium perchlorate. The oxidation of each petroleum oil was carried out in two steps; the first step consisted of oxidation of the feed at moderate temperature and atmospheric pressure while in the second step, the oxidized mixture was extracted with azeotropic mixture of acetonitrile-water. A maximum desulphurization has occurred with NaClO{sub 4} and hydrogen peroxide and acetic acid, which are 68% and 61%, respectively in case of gasoline and 66% and 63%, respectively in case of kerosene oil. The FTIR study of the whole and variously desulphurized gasoline and kerosene was also carried out. The results indicate considerable desulphurization by absence of bands that corresponds to sulphur moieties in NaClO{sub 4} and hydrogen peroxide treated samples. (author)

  9. Laboratory Oxidation Stability Study on B10 Biodiesel Blends

    Energy Technology Data Exchange (ETDEWEB)

    Engelen, B. [and others

    2013-11-15

    A laboratory oxidation stability study has been completed jointly by CONCAWE and DGMK on three biodiesel blends containing 10% v/v (B10) Fatty Acid Methyl Ester (FAME). The results of the study are compared to measurements from an in-vehicle storage stability study on similar B10 diesel fuels that had been conducted previously in a Joint Industry Study. This laboratory study monitored the oxidation stability of the three B10 blends during six weeks of laboratory storage under ambient (25C) and elevated temperature (43C) conditions. Various test methods were used to monitor oxidation stability changes in the B10 diesel fuel blends including electrical conductivity, viscosity, Rancimat oxidation stability (EN 15751), PetroOxy oxidation stability (EN 16091), acid number (EN 14104), Delta Total Acid Number (Delta TAN), and peroxide number (ISO 3960). Elemental analyses by ICP were also completed on the FAME and B10 blends at the start and end of the laboratory study. The concentrations of dissolved metals were very low in all cases except for silicon which was found to be between about 600-700 ppb in the B10 blends. A limited study was also conducted on one neat FAME sample (B100) to investigate the effect of air/oxygen exposure on the rate of decrease in oxidation stability.

  10. Preparation and study of properties of dispersed graphene oxide

    Directory of Open Access Journals (Sweden)

    Evgeniya Seliverstova

    2015-09-01

    Full Text Available Ability of graphene oxide to form stable dispersion in organic solvents was studied in this work. As it was shown, sonication of graphene leads to the decreas of the particle size. Stability of prepared graphene dispersions was studied upon measurements of distribution of number of the particles via size and change of optical density of the solutions with time. It was found that graphene oxide forms a more stable dispersion in tetrahydrofuran and dimethylformamide than in chloroform and acetone.

  11. SIMS and TEM study on oxide characteristics of Zircaloy

    International Nuclear Information System (INIS)

    Jung, Y. H.; Baek, J. H.; Kim, S. J.; Kim, K. H.; Choi, B. K.; Jung, Y. H.

    1998-01-01

    Long-term corrosion test, SIMS analysis, and TEM study were carried out to investigate the corrosion characteristics and corrosion mechanism of Zircaloy-4 in LiOH solution. The corrosion tests were performed in alkali solutions at 350 deg C for 500days. SIMS analysis was performed for the specimens prepared to have an equal oxide thickness to measure the cation content. TEM studies on the samples formed in various alkali solutions were also conducted. Based on the corrosion test, SIMS analysis, and TEM study, the cation is considered to control the corrosion in LiOH solution and its effect is dependent on the concentration of alkali and the oxide thickness. The slight acceleration of corrosion rate at a low concentration is thought to be caused by the cation incorporation into oxide while the significant acceleration at a high concentration is due to the transformation of oxide microstructure that would be induced by the cation incorporation

  12. A study on the utilization of chromic oxide wastes

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Seung Woong; Kim, Chi Kwon; Hwang, Seon Kook; Kim, Byung Gyu; Son, Jeong Soo; Nam, Chul Woo [Korea Inst. of Geology Mining and Materials, Taejon (Korea, Republic of)

    1995-12-01

    This study was carried out to develop the optimum process for recovering precious and valuable metals from chrome oxide wastes. The following subjects such as, (1) feasibility on the recovery of precious and valuable metals, (2) recovery rate of precious and valuable metals, (3) purification of extracted precious and valuable metals, and (4) environmental aspects of recovery process, were investigated and the main results are as follows. (1) With Sem analysis of chrome oxide wastes, it was found that combustion process for eliminating oil and water in wastes, was necessary. (2) After leaching chrome oxide wastes with nitric acid and aqua regia, silver and gold were effectively separated and recovered. But a lot of silver and gold were remaining in the leaching residue. It was considered that chrome oxide powder was coated with organic materials during polishing stage and their products were insoluble in acidic solution. (3) The optimum process for separation and recovery of precious metal and production of new chrome oxide is consist of several process such as perchloric acid leaching, recovery of silver chloride, cementation for gold, reduction of chrome ion, and production of pure chrome oxide. (4) For separating chrome compound from the chrome oxide waste occurred in stainless steel polishing process, alkali roasting process was suggested. (author). 18 refs., 29 figs., 11 tabs.

  13. Fuel cells: spectroscopic studies in the electrocatalysis of alcohol oxidation

    OpenAIRE

    Iwasita Teresa

    2002-01-01

    Modern spectroscopic methods are useful for elucidating complex electrochemical mechanisms as those occurring during the oxidation of small organic molecules (CH3OH, HCOH, HCOOH). In the present paper it is shown the use of spectroscopic methods to study the oxidation of alcohols on platinum or Pt-based binary electrodes. These reactions are of importance in conexion with the development of anode systems for use in fuel cells. Mass spectrometry and FT infrared spectroscopy allow to establishi...

  14. Study of oxide layers in creep of Ti alloy

    International Nuclear Information System (INIS)

    Reis, D.A.P.; Moura Neto, C.; Machado, J.P.B.; Martins, G.V.; Barboza, M.J.R.

    2009-01-01

    The present study is about the effect of oxide layers in creep of Ti-6Al-4V alloy, in different atmospheres (air, nitrogen and argon). Ti-6Al-4V alloy was treated during 24 hours in a thermal treatment furnace at 600°C in different atmospheres (argon, nitrogen and air). The samples were analyzed by High Resolution X-Ray Diffraction, Scanning Electronic Microscopy (SEM), Atomic Force Microscopy (AFM) and microhardness test. The polished samples of Ti-6Al-4V alloy were treated during 24 hours at 600°C and the oxidation behavior in each case using argon, nitrogen and air atmospheres was observed. The oxidation was more aggressive in air atmosphere, forming TiO 2 film in the surface. The oxidation produced a weight gain through the oxide layer growth and hardening by oxygen dissolution. Ti-6Al-4V alloy specimens also were produced in order to test them in creep, at 250 MPa and 600 deg C, with argon, nitrogen and air atmospheres. When the Ti-6Al-4V alloy was tested under argon and nitrogen atmospheres oxidation effects are smaller and the behavior of the creep curves shows that the creep life time was better in atmospheres not so oxidant. It is observed a decreasing of steady state creep in function of the oxidation process reduction. It is shown that, for the Ti-6Al-4V alloy, their useful life is strongly affected by the atmosphere that is submitted, on account of the oxidation suffered by the material. (author)

  15. Acetaldehyde as an Intermediate in the Electroreduction of Carbon Monoxide to Ethanol on Oxide-Derived Copper

    DEFF Research Database (Denmark)

    Bertheussen, Erlend; Verdaguer Casadevall, Arnau; Ravasio, Davide

    2016-01-01

    Oxide-derived copper (OD-Cu) electrodes exhibit unprecedented CO reduction performance towards liquid fuels, producing ethanol and acetate with >50 % Faradaic efficiency at −0.3 V (vs. RHE). By using static headspace-gas chromatography for liquid phase analysis, we identify acetaldehyde as a mino...... solutions using NMR spectroscopy, requiring alternative methods for detection and quantification. Our results represent an important step towards understanding the CO reduction mechanism on OD-Cu electrodes....

  16. SIMS studies of oxide growth on beta-NiAl

    Science.gov (United States)

    Mitchell, D. F.; Prescott, R.; Graham, M. J.; Doychak, J.

    1992-01-01

    This paper reports on a study of the growth of aluminum oxide on beta-NiAl at temperatures up to 1200 C. The scales have been formed in two-stage experiments using O2-16 and O2-18 gases, and the various isotopic species have been located by direct imaging using SIMS. Supplementary information on oxide morphologies and structures has been obtained by SEM. SIMS images and depth profiles indicate where oxidation has taken place predominantly by cation or anion diffusion at different stages of the growth process. The way in which the presence of small amounts of reactive elements can affect scale growth is also considered. These results help to provide an improved understanding of the mechanism of alumina scale formation, which is of benefit in the development of oxidation-resistant alloys and intermetallics for service at high temperatures.

  17. A Study on the Oxidative-dissolution Leaching of Fission Product Oxides in the carbonate solution

    International Nuclear Information System (INIS)

    Lee, Eil Hee; Kim, Kwang Wook; Lim, Jae Gwan; Chung, Dong Yong; Yang, Han Beom; Joe, Kih Soo; Seo, Heui Seung; Kim, Yeon Hwa; Lee, Se Yoon

    2009-07-01

    This study was carried out to investigate the characteristics of an oxidativedissolution leaching of FP co-dissolved with U in a carbonate solution of Na 2 CO 3 - H 2 O 2 and (NH 4 ) 2 CO 3 -H 2 O 2 , respectively. Simulated FP-oxides which contained 12 components have been added to the solution to examine their oxidative dissolution characteristics. It was found that H 2 O 2 was an effective oxidant to minimize the dissolution of FP in a carbonate solution. In 0.5M Na 2 CO 3 -0.5M H 2 O 2 and 0.5M (NH 4 ) 2 CO 3 -0.5M H 2 O 2 solution, some elements such as Re, Te, Cs and Mo seem to be dissolved together with U. It is revealed that dissolution rates of Re, Te and Cs are high (completely dissolved within 10∼20 minutes) due to their high solubility in Na 2 CO 3 and (NH 4 ) 2 CO 3 solution regardless of the addition of H 2 O 2 , and independent of the concentrations of Na 2 CO 3 and H 2 O 2 . However, Mo was slowly dissolved by an oxidative dissolution with H 2 O 2 . It is found that the most important factor for the oxidative dissolution of FP is the pH of the solution and an effective oxidative dissolution is achieved at a pH between 10∼12 for Na 2 CO 3 and a pH between 9∼10 for (NH 4 ) 2 CO 3 , respectively, in order to minimize the dissolution of FP

  18. Structural basis of protein oxidation resistance: a lysozyme study.

    Directory of Open Access Journals (Sweden)

    Marion Girod

    Full Text Available Accumulation of oxidative damage in proteins correlates with aging since it can cause irreversible and progressive degeneration of almost all cellular functions. Apparently, native protein structures have evolved intrinsic resistance to oxidation since perfectly folded proteins are, by large most robust. Here we explore the structural basis of protein resistance to radiation-induced oxidation using chicken egg white lysozyme in the native and misfolded form. We study the differential resistance to oxidative damage of six different parts of native and misfolded lysozyme by a targeted tandem/mass spectrometry approach of its tryptic fragments. The decay of the amount of each lysozyme fragment with increasing radiation dose is found to be a two steps process, characterized by a double exponential evolution of their amounts: the first one can be largely attributed to oxidation of specific amino acids, while the second one corresponds to further degradation of the protein. By correlating these results to the structural parameters computed from molecular dynamics (MD simulations, we find the protein parts with increased root-mean-square deviation (RMSD to be more susceptible to modifications. In addition, involvement of amino acid side-chains in hydrogen bonds has a protective effect against oxidation Increased exposure to solvent of individual amino acid side chains correlates with high susceptibility to oxidative and other modifications like side chain fragmentation. Generally, while none of the structural parameters alone can account for the fate of peptides during radiation, together they provide an insight into the relationship between protein structure and susceptibility to oxidation.

  19. A study of oxidative stress in paucibacillary and multibacillary leprosy

    Directory of Open Access Journals (Sweden)

    Jyothi P

    2008-01-01

    Full Text Available Background: The study and assessment of oxidative stress plays a significant role in the arena of leprosy treatment. Once the presence of oxidative stress is proved, antioxidant supplements can be provided to reduce tissue injury and deformity. Aim: To study oxidative stress in paucibacillary (PB and multibacillary (MB leprosy and to compare it with that in a control group. Methods: Fifty-eight untreated leprosy patients (23 PB and 35 MB cases were studied and compared with 58 healthy controls. Superoxide dismutase (SOD level as a measure of antioxidant status; malondialdehyde (MDA level, an indicator of lipid peroxidation; and MDA/SOD ratio, an index of oxidative stress were estimated in the serum. Results: The SOD level was decreased in leprosy patients, especially in MB leprosy. The MDA level was increased in PB and MB leprosy. The MDA/SOD ratio was significantly elevated in MB patients. There was a steady increase in this ratio along the spectrum from tuberculoid to lepromatous leprosy (LL. Conclusion: There is increased oxidative stress in MB leprosy, especially in LL. This warrants antioxidant supplements to prevent tissue injury.

  20. The initial growth of complex oxides : study and manipulation

    NARCIS (Netherlands)

    Rijnders, Augustinus J.H.M.

    2001-01-01

    In this thesis, the initial growth stage, i.e., nucleation and growth of the first few unit cell layers, of complex oxides was studied in real time during pulsed laser deposition (PLD). These studies were performed at their optimal epitaxial growth conditions, i.e., high temperature and high oxygen

  1. Study of optics anisotropy of niobium oxide

    International Nuclear Information System (INIS)

    Ferreira, N.G.; Decker, F.; Fracastoro-Decker, M.

    1988-01-01

    This work shows the use of ''in-situ'' optical techniques in electrochemical experiments to determine the refractive indexes of an anisotropic film. ''In situ'' reflectance measurements allow to study the behavior of a film during its growth process: in our case, since Nb 2 O 5 films are anisotropic only in the presence of an electric field, an ''in-situ'' technique is the only one appropriate to detect this phenomenon. (author) [pt

  2. Positron lifetime studies on thorium oxide powders

    International Nuclear Information System (INIS)

    Upadhyaya, D.D.; Muraleedharan, R.V.; Sharma, B.D.

    1982-01-01

    Positron lifetime spectra have been studied for ThO 2 powders, calcined at different temperatures and having different particle sizes. Three lifetime components could be resolved, the longest component being of low intensity. An observed strong dependence on the particle size of the annihilation process and the variation of positronium diffusion constant is explained on the basis of defect density variations in these powders. (author)

  3. Effect of Shisha (Waterpipe Smoking on Lung Functions and Fractional Exhaled Nitric Oxide (FeNO among Saudi Young Adult Shisha Smokers

    Directory of Open Access Journals (Sweden)

    Sultan Ayoub Meo

    2014-09-01

    Full Text Available Shisha (waterpipe smoking is becoming a more prevalent form of tobacco consumption, and is growing worldwide, particularly among the young generation in the Middle East. This cross-sectional study aimed to determine the effects of shisha smoking on lung functions and Fractional Exhaled Nitric Oxide (FeNO among Saudi young adults. We recruited 146 apparently healthy male subjects (73 control and 73 shisha smokers. The exposed group consisted of male shisha smokers, with mean age 21.54 ± 0.41 (mean ± SEM range 17–33 years. The control group consisted of similar number (73 of non-smokers with mean age 21.36 ± 0.19 (mean ± SEM range 18–28 years. Between the groups we considered the factors like age, height, weight, gender, ethnicity and socioeconomic status to estimate the impact of shisha smoking on lung function and fractional exhaled nitric oxide. Lung function test was performed by using an Spirovit-SP-1 Electronic Spirometer. Fractional Exhaled Nitric Oxide (FeNO was measured by using Niox Mino. A significant decrease in lung function parameters FEV1, FEV1/FVC Ratio, FEF-25%, FEF-50%, FEF-75% and FEF-75–85% was found among shisha smokers relative to their control group. There was also a significant reduction in the Fractional Exhaled Nitric Oxide among Shisha smokers compared to control group.

  4. Experimental study on oxidation and combustion characteristics of sodium droplets

    International Nuclear Information System (INIS)

    Zhang Zhigang; Sun Shubin; Liu Chongchong; Tang Yexin

    2015-01-01

    In the operation of the sodium-cooled fast reactor, the accident caused by the leakage and combustion of liquid sodium is common and frequent. In this paper, the oxidation and combustion characteristics of sodium droplets were studied by carrying out the experiments of the oxidation and combustion under different conditions of initial temperatures (140-370℃) of the sodium droplets and oxygen concentrations (4%-21%). The oxidation and combustion behaviors were visualized by a set of combustion apparatus of sodium droplet and a high speed camera. The experiment results show that the columnar oxides grow longer as the initial temperature of sodium droplet and oxygen concentration become lower. Under the same oxygen concentration condition, the sodium droplet with the higher initial temperature is easier to ignite and burn. When the initial temperature of sodium droplet is below 200℃, it is very difficult to ignite. If there is a turbulence damaging the oxide layer on the surface, the sodium droplet will also burn gradually. When the initial temperature ranges from 140℃ to 370℃ and the oxygen fraction is equal to or higher than 12%, the sodium droplet could burn completely and the maximum combustion temperature could roughly reach 600-800℃. When the oxygen concentration is below 12%, the sodium droplet could not burn completely and the highest combustion temperature is below 600℃. The results are helpful to the research on the columnar flow and spray sodium fire. (authors)

  5. Study on thermodynamic properties of actinoid oxides

    Energy Technology Data Exchange (ETDEWEB)

    Tsuji, Toshihide; Miyajima, Nobuyoshi; Kato, Tetsuya; Ochida, Manabu [Nagoya Univ. (Japan). School of Engineering; Mumomura, Tadasumi; Yamashita, Toshiyuki; Nitani, Noriko; Ouchi, Kinji

    1996-01-01

    Since long-life transuranium elements (TRU) accumulate associated with a progress of high-burnup of fuel, TRU quenching in a reactor or an accelerator has been examined in Japan. To design a fuel for TRU quenching, thermal expansion is an important thermal parameter along with thermal capacity and heat transfer coefficient. Here, lattice constants of PuO{sub 2} ThO{sub 2}, UO{sub 2} and NpO{sub 2} were investigated by high temperature X-ray diffraction, showing that the lattice constants of these dioxides but UO{sub 2} obtained in this study were well coincident with Tailor`s values. The linear expansion coefficients for ThO{sub 2}, UO{sub 2} and PuO{sub 2} agreed with TPRC data and that of NpO{sub 2} with Fahey`s measurement. The linear expansion coefficient of NpO{sub 2} was found to be temperature dependent as well as other three dioxides. Those values were in inverse proportion to their melting points in a higher temperature range, whereas in a lower temperature one, the coefficient of UO{sub 2} was larger than those of NpO{sub 2} and PuO{sub 2}. Therefore, such abnormal behavior of the coefficient in a low temperature range was considered to be related to the lower Debye temperature of UO{sub 2} compared with the other dioxides. (M.N.)

  6. Pulse radiolysis study on oxidation reactions of gallic acid

    International Nuclear Information System (INIS)

    Dwibedy, P.; Dey, G.R.; Naik, D.B.; Kishore, Kamal

    1998-01-01

    Reactions of OH . /O - and other oxidising radicals viz. N 3 . , Br 2 .- , Cl 2 .- with gallic acid (GA) have been studied at various pHs. At pH 6.8, OH . radicals react with GA giving an adduct which in turn reacts with the parent GA to give a dimeric species. At pH 9.7, the initial OH adduct formed is able to oxidize GA to give a semi-oxidised species. At pH 12 and ∼ 13.6, OH . /O .- radicals directly bring about oxidation of GA. (author)

  7. ONIOM Studies of Esterification at Oxidized Carbon Nanotube Tips

    Energy Technology Data Exchange (ETDEWEB)

    Contreras-Torres, F F; Basiuk, V A [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior C.U., A. Postal 70-543, 04510 Mexico D. F. (Mexico)

    2007-03-15

    Esterification of oxidized carbon nanotubes (CNTs) can open a new route for the separation of zigzag and armchair nanotubes. We studied theoretically (by using hybrid DFT within the ONIOM embedding protocol) the reactions of monocarboxy-substituted oxidized tips of zigzag and armchair single-walled CNTs (SWCNTs) with methanol. According to the calculated values of activation energy, Gibbs free-activation barriers, and enthalpies of formation for the SWCNT-(COOH)H5 models, the zigzag nanotube isomer is more reactive as compared to its armchair counterpart. For other models we obtained variable results.

  8. Fuel cells: spectroscopic studies in the electrocatalysis of alcohol oxidation

    Directory of Open Access Journals (Sweden)

    Iwasita Teresa

    2002-01-01

    Full Text Available Modern spectroscopic methods are useful for elucidating complex electrochemical mechanisms as those occurring during the oxidation of small organic molecules (CH3OH, HCOH, HCOOH. In the present paper it is shown the use of spectroscopic methods to study the oxidation of alcohols on platinum or Pt-based binary electrodes. These reactions are of importance in conexion with the development of anode systems for use in fuel cells. Mass spectrometry and FT infrared spectroscopy allow to establishing the reaction intermediates and products and the dependence of the amount of species on the applied potential. FTIR and scanning tunneling microscopy contribute to understand the effects of the surface structure on the rate of reaction. Examples are presented for methanol and ethanol oxidation at pure and modified Pt catalysts.

  9. Positron studies of metal-oxide-semiconductor structures

    Science.gov (United States)

    Au, H. L.; Asoka-Kumar, P.; Nielsen, B.; Lynn, K. G.

    1993-03-01

    Positron annihilation spectroscopy provides a new probe to study the properties of interface traps in metal-oxide semiconductors (MOS). Using positrons, we have examined the behavior of the interface traps as a function of gate bias. We propose a simple model to explain the positron annihilation spectra from the interface region of a MOS capacitor.

  10. Study of oxide facing at silicone detectors of ionization detectors

    International Nuclear Information System (INIS)

    Kopestansky, J.; Tykva, R.

    1999-01-01

    Formation of oxide facing on silicone in discrete phases of technological preparation of detectors and interaction of gold (aluminium) steamed with SiO x layer were studied. The homogeneity of Au and Si) x layers and interface Au-SiO x and SiO x -Si were examined. The methods SIMS, and partially XPS, AES and RBS were used

  11. Physical and electrochemical study of cobalt oxide nano- and microparticles

    Energy Technology Data Exchange (ETDEWEB)

    Alburquenque, D. [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile); Dpto. de Metalurgia, USACh, Av. Ecuador 3469, 9170124, Santiago (Chile); Vargas, E. [Dpto. de Física, USACh and CEDENNA, Av. Ecuador 3493, 9170124 Santiago (Chile); Dpto. de Metalurgia, USACh, Av. Ecuador 3469, 9170124, Santiago (Chile); Denardin, J.C.; Escrig, J. [Dpto. de Física, USACh and CEDENNA, Av. Ecuador 3493, 9170124 Santiago (Chile); Marco, J.F. [Instituto de Química Física “Rocasolano”, CSIC, c/Serrano 119, 28006 Madrid (Spain); Ortiz, J. [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile); Gautier, J.L., E-mail: juan.gautier@usach.cl [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile)

    2014-07-01

    Cobalt oxide nanocrystals of size 17–21 nm were synthesized by a simple reaction between cobalt acetate (II) and dodecylamine. On the other hand, micrometric Co{sub 3}O{sub 4} was prepared using the ceramic method. The structural examination of these materials was performed using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM and HRTEM). XRD studies showed that the oxides were pure, well-crystallized, spinel cubic phases with a-cell parameter of 0.8049 nm and 0.8069 nm for the nano and micro-oxide, respectively. The average particle size was 19 nm (nano-oxide) and 1250 μm (micro-oxide). Morphological studies carried out by SEM and TEM analyses have shown the presence of octahedral particles in both cases. Bulk and surface properties investigated by X-ray photoelectron spectroscopy (XPS), point zero charge (pzc), FTIR and cyclic voltammetry indicated that there were no significant differences in the composition on both materials. The magnetic behavior of the samples was determined using a vibrating sample magnetometer. The compounds showed paramagnetic character and no coercivity and remanence in all cases. Galvanostatic measurements of electrodes formed with nanocrystals showed better performance than those built with micrometric particles. - Highlights: • Spinel Co{sub 3}O{sub 4} nanoparticles and microparticles with same structure but with different cell parameters, particle size and surface area were synthesized. • Oxide nanoparticles showed better electrochemical behavior than micrometric ones due to area effect.

  12. Study of Oxide Formation on Alloy 800 by Potentiostatic Polarization

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Chong Hun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Momenib, M.; Wren, C. J. [University of Western Ontario, London (Canada)

    2015-10-15

    The objectives of study are to investigate the effect of potential on oxide formation and conversion on alloy 800 under potentiostatic conditions. For this study we have focused primarily on corrosion at pH{sub 25.}deg. C8.4. The results presented in Figures 1 show that in the range from -0.8 V{sub SCE} to +0.2 V{sub SCE} there are four potential regions having distinctly different short- and long-term characteristics in the log |i| vs. log t and Q vs. t plots. At a potential below -0.8 V{sub SCE}, the current becomes cathodic immediately (< 10 s) upon polarization, indicating negligible metal oxidation and hence is not of interest. In nuclear power plants, it is used for steam generator tubing in pressurized water reactors (PWRs), including Canadian Deuterium Uranium (CANDU) reactors. However, failures resulting from localized corrosion such as pitting, crevice and stress corrosion cracking (SCC) have been observed in the service environments. There exists still considerable controversy over the type of oxide that can be formed and the mechanism of oxide formation on Alloy 800.

  13. Graphene oxide and adsorption of chloroform: A density functional study

    Energy Technology Data Exchange (ETDEWEB)

    Kuisma, Elena; Hansson, C. Fredrik; Lindberg, Th. Benjamin; Gillberg, Christoffer A.; Idh, Sebastian; Schröder, Elsebeth, E-mail: schroder@chalmers.se [Quantum Device Physics Laboratory, Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Göteborg (Sweden)

    2016-05-14

    Chlorinated hydrocarbon compounds are of environmental concerns, since they are toxic to humans and other mammals, and are widespread, and exposure is hard to avoid. Understanding and improving methods to reduce the amount of the substances are important. We present an atomic-scale calculational study of the adsorption of chlorine-based substance chloroform (CHCl{sub 3}) on graphene oxide, as a step in estimating the capacity of graphene oxide for filtering out such substances, e.g., from drinking water. The calculations are based on density functional theory, and the recently developed consistent-exchange functional for the van der Waals density-functional method is employed. We obtain values of the chloroform adsorption energy varying from roughly 0.2 to 0.4 eV per molecule. This is comparable to previously found results for chloroform adsorbed directly on clean graphene, using similar calculations. In a wet environment, like filters for drinking water, the graphene will not stay clean and will likely oxidize, and thus adsorption onto graphene oxide, rather than clean graphene, is a more relevant process to study.

  14. Heritability of Biomarkers of Oxidized Lipoproteins: Twin Pair Study.

    Science.gov (United States)

    Rao, Fangwen; Schork, Andrew J; Maihofer, Adam X; Nievergelt, Caroline M; Marcovina, Santica M; Miller, Elizabeth R; Witztum, Joseph L; O'Connor, Daniel T; Tsimikas, Sotirios

    2015-07-01

    To determine whether biomarkers of oxidized lipoproteins are genetically determined. Lipoprotein(a) (Lp[a]) is a heritable risk factor and carrier of oxidized phospholipids (OxPL). We measured oxidized phospholipids on apolipoprotein B-containing lipoproteins (OxPL-apoB), Lp(a), IgG, and IgM autoantibodies to malondialdehyde-modified low-density lipoprotein, copper oxidized low-density lipoprotein, and apoB-immune complexes in 386 monozygotic and dizygotic twins to estimate trait heritability (h(2)) and determine specific genetic effects among traits. A genome-wide linkage study followed by genetic association was performed. The h(2) (scale: 0-1) for Lp(a) was 0.91±0.01 and for OxPL-apoB 0.87±0.02, which were higher than physiological, inflammatory, or lipid traits. h(2) of IgM malondialdehyde-modified low-density lipoprotein, copper oxidized low-density lipoprotein, and apoB-immune complexes were 0.69±0.04, 0.67±0.05, and 0.80±0.03, respectively, and for IgG malondialdehyde-modified low-density lipoprotein, copper oxidized low-density lipoprotein, and apoB-immune complexes 0.62±0.05, 0.52±0.06, and 0.53±0.06, respectively. There was an inverse correlation between the major apo(a) isoform and OxPL-apoB (R=-0.49; Plipoprotein and copper oxidized low-density lipoprotein, and apoB-immune complexes. Sib-pair genetic linkage of the Lp(a) trait revealed that single nucleotide polymorphism rs10455872 was significantly associated with OxPL-apoB after adjusting for Lp(a). OxPL-apoB and other biomarkers of oxidized lipoproteins are highly heritable cardiovascular risk factors that suggest novel genetic origins of atherothrombosis. © 2015 American Heart Association, Inc.

  15. A comparison study between ZnO nanorods coated with graphene oxide and reduced graphene oxide

    International Nuclear Information System (INIS)

    Ding, Jijun; Wang, Minqiang; Deng, Jianping; Gao, Weiyin; Yang, Zhi; Ran, Chenxin; Zhang, Xiangyu

    2014-01-01

    Highlights: • Optical properties between ZnO-GO and ZnO-RGO composites were compared. • Photoluminescence quenching was observed in ZnO-GO composites. • We obtained enhanced photoluminescence in ZnO-RGO composites. -- Abstract: ZnO nanorods (ZnO NRs) coated with graphene oxide (ZnO-GO) and reduced graphene oxide sheets (ZnO-RGO) were prepared on indium tin oxide (ITO) substrates. The crystal structures, morphology and optical properties were analyzed by using X-ray diffraction (XRD) pattern, scanning electron microscopy (SEM) images, absorption spectra and photoluminescence (PL) spectra, respectively. A comparison between PL properties from ZnO-GO and ZnO-RGO were studied. Results indicated that the peak at 442 nm and a broad band at 450–600 nm of ZnO NRs show PL quenching after coating with GO sheets. As coating with RGO sheets, the extent of PL quenching increases. It is interesting to note that as ZnO NRs coated with RGO sheets, the intensity of PL peak at 390 nm significantly increased. The enhanced PL emission research in ZnO-RGO is directed toward development of the “nextgeneration” optoelectronics devices related with graphene materials

  16. Contribution to the study of ruthenium fluorides, oxyfluorides and oxides

    International Nuclear Information System (INIS)

    Corbin, Odile.

    1982-08-01

    Studies on the dry processing of spent fuels reveal a poor ruthenium decontamination of plutonium. For a better understanding of this result a study of ruthenium fluorides, oxyfluorides and oxides is carried out here as follows: - bibliographical review; - thermochromatographic identification of the number and nature of compounds formed by fluorination of microquantities of ruthenium; - confirmation of the thermochromatographic results by two other analytical methods: thermogravimetry and infrared spectroscopy [fr

  17. Study on the solid state chemistry of ternary uranium oxides

    International Nuclear Information System (INIS)

    Yamashita, Toshiyuki

    1988-03-01

    With the increase of burnup of uranium oxide fuels, various kinds of fission products are formed, and the oxygen atoms combined with the consumed heavy atoms are freed. The solid state chemical and/or thermodynamic properties of these elements at high temperatures are complex, and have not been well clarified. In the present report, an approach was taken that the chemical interactions between UO 2 and these fission products can be regarded as causing overlapped effects of composing ternary uranium oxides, and formation reactions and phase behavior were studied for several ternary uranium oxides with typical fission product elements such as alkaline earth metals and rare earth elements. Precise determination methods for the composition of ternary uranium oxides were developed. The estimated accuracies for x and y values in M y U 1-y O 2+x were ± 0.006 and ± 0.004, respectively. The thermodynamic properties and the lattice parameters of the phases in the Ca-U-O and Pr-U-O systems were discussed in relation to the composition determined by the methods. Crystal structure analyses of cadmium monouranates were made with X-ray diffraction method. (author) 197 refs

  18. MECHANISTIC STUDY OF COLCHICINE’s ELECTROCHEMICAL OXIDATION

    International Nuclear Information System (INIS)

    Bodoki, Ede; Chira, Ruxandra; Zaharia, Valentin; Săndulescu, Robert

    2015-01-01

    Colchicine, as one of the most ancient drugs of human kind, is still in the focal point of the current research due to its multimodal mechanism of action. The elucidation of colchicine’s still unknown redox properties may play an important role in deciphering its beneficial and harmful implications over the human body. Therefore, a systematic mechanistic study of colchicine’s oxidation has been undertaken by electrochemistry coupled to mass spectrometry using two different types of electrolytic cells, in order to clarify the existing inconsistencies with respect to this topic. At around 1 V vs. Pd/H 2 , initiated by a one-electron transfer, the oxidation of colchicine sets off leading to a cation radical, whose further oxidation may evolve on several different pathways. The main product of the anodic electrochemical reaction, regardless of the carrier solution’s pH is represented by a 7-hydroxy derivative of colchicine. At more anodic potentials (above 1.4 V vs. Pd/H 2 ) compounds arising from epoxidation and/or multiple hydroxylation occur. No di- or tridemethylated quinone structures, as previously suggested in the literature for the electrolytic oxidation of colchicine, has been detected in the mass spectra.

  19. Molecular modeling studies of oleate adsorption on iron oxides

    Energy Technology Data Exchange (ETDEWEB)

    Rath, Swagat S. [CSIR-Institute of Minerals and Materials Technology, Bhubaneswar (India); Sinha, Nishant [Accelrys K.K, Bengaluru (India); Sahoo, Hrushikesh [CSIR-Institute of Minerals and Materials Technology, Bhubaneswar (India); Das, Bisweswar, E-mail: bdas@immt.res.in [CSIR-Institute of Minerals and Materials Technology, Bhubaneswar (India); Mishra, Barada Kanta [CSIR-Institute of Minerals and Materials Technology, Bhubaneswar (India)

    2014-03-01

    Graphical abstract: - Highlights: • Plane wave periodic DFT study of oleate-iron oxide interaction. • Magnetite-oleate complex is more stable than hematite and goethite. • Flotation recovery of magnetite is more compared to the other two oxides. - Abstract: Comparative studies of oleate interaction with hematite, magnetite and goethite using density functional calculations are presented. The approach is illustrated by carrying out geometric optimization of oleate on the stable and most exposed planes of hematite, magnetite, and goethite. Interaction energies for oleate-mineral surface have been determined, based on which, magnetite is found to be forming the most stable complex with oleate. Trend as obtained from the quantum chemical calculations has been validated by contact angle measurements and flotation studies on hematite, magnetite and goethite with sodium oleate at different pH and collector concentrations.

  20. Molecular modeling studies of oleate adsorption on iron oxides

    International Nuclear Information System (INIS)

    Rath, Swagat S.; Sinha, Nishant; Sahoo, Hrushikesh; Das, Bisweswar; Mishra, Barada Kanta

    2014-01-01

    Graphical abstract: - Highlights: • Plane wave periodic DFT study of oleate-iron oxide interaction. • Magnetite-oleate complex is more stable than hematite and goethite. • Flotation recovery of magnetite is more compared to the other two oxides. - Abstract: Comparative studies of oleate interaction with hematite, magnetite and goethite using density functional calculations are presented. The approach is illustrated by carrying out geometric optimization of oleate on the stable and most exposed planes of hematite, magnetite, and goethite. Interaction energies for oleate-mineral surface have been determined, based on which, magnetite is found to be forming the most stable complex with oleate. Trend as obtained from the quantum chemical calculations has been validated by contact angle measurements and flotation studies on hematite, magnetite and goethite with sodium oleate at different pH and collector concentrations

  1. Water Sorption and Gamma Radiolysis Studies for Uranium Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Icenhour, A.S.

    2002-02-27

    During the development of a standard for the safe, long-term storage of {sup 233}U-containing materials, several areas were identified that needed additional experimental studies. These studies were related to the perceived potential for the radiolytic generation of large pressures or explosive concentrations of gases in storage containers. This report documents the results of studies on the sorption of water by various uranium oxides and on the gamma radiolysis of uranium oxides containing various amounts of sorbed moisture. In all of the experiments, {sup 238}U was used as a surrogate for the {sup 233}U. For the water sorption experiments, uranium oxide samples were prepared and exposed to known levels of humidity to establish the water uptake rate. Subsequently, the amount of water removed was studied by heating samples in a oven at fixed temperatures and by thermogravimetric analysis (TGA)/differential thermal analysis (DTA). It was demonstrated that heating at 650 C adequately removes all moisture from the samples. Uranium-238 oxides were irradiated in a {sup 60}Co source and in the high-gamma-radiation fields provided by spent nuclear fuel elements of the High Flux Isotope Reactor. For hydrated samples of UO{sub 3}, H{sub 2} was the primary gas produced; but the total gas pressure increase reached steady value of about 10 psi. This production appears to be a function of the dose and the amount of water present. Oxygen in the hydrated UO{sub 3} sample atmosphere was typically depleted, and no significant pressure rise was observed. Heat treatment of the UO{sub 3} {center_dot} xH{sub 2}O at 650 C would result in conversion to U{sub 3}O{sub 8} and eliminate the H{sub 2} production. For all of the U{sub 3}O{sub 8} samples loaded in air and irradiated with gamma radiation, a pressure decrease was seen and little, if any, H{sub 2} was produced--even for samples with up to 9 wt % moisture content. Hence, these results demonstrated that the efforts to remove trace

  2. Catalytic activity trends of CO oxidation – A DFT study

    DEFF Research Database (Denmark)

    Jiang, Tao

    theoretical study of CO oxidation with experimental studies. The latter shows promoted catalytic activity when gold particle size decreases to 5 nm. Oxidizing CO by N2O was found to involve a CO␣O transition state, with atomic O adsorbed on the gold B5 sites and CO on the corners. On the other hand, CO...... and experiment were found to be the same. The experiment findings are in good agreement with our theoretical calculations. The second part of the thesis focuses on improving the convergence property of Quasi-Newton algorithm. The eigenvalues of the Hessian matrix of 54 atoms bulk Cu model are calculated......, and the sizes of eigenvalues follow power-law distribution. It is found that the anharmonicity of the weak modes lead to poor Newton step and poor Hessian update in BFGS type Quasi-Newton algorithm, which slow down the geometry optimization. Line search that fulfills Wolff conditions is then applied to improve...

  3. The GC/AED studies on the reactions of sulfur mustard with oxidants

    International Nuclear Information System (INIS)

    Popiel, StanisIaw; Witkiewicz, Zygfryd; Szewczuk, Aleksander

    2005-01-01

    A gas chromatograph coupled with an atomic emission detector was used to identify and to determine the products formed on oxidation of sulfur mustard. The oxidation rate and the resulting oxidates were studied in relation to oxidant type and reaction medium parameters. Hydrogen peroxide, sodium hypochlorite, sodium perborate, potassium monopercarbonate, ammonium peroxydisulfate, potassium peroxymonosulfate (oxone), and tert-butyl peroxide were used as oxidants. Oxidations were run in aqueous media or in solvents of varying polarities. The oxidation rate was found to be strongly related to oxidant type: potassium peroxymonosulfate (oxone) and sodium hypochlorite were fast-acting oxidants; sodium perborate, hydrogen peroxide, ammonium peroxydisulfate, and sodium monopercarbonate were moderate oxidants; tert-butyl peroxide was the slowest-acting oxidant. In non-aqueous solvents, the oxidation rate was strongly related to solvent polarity. The higher the solvent polarity, the faster the oxidation rate. In the acid and neutral media, the mustard oxidation rates were comparable. In the alkaline medium, oxidation was evidently slower. A suitable choice of the initial oxidant-to-mustard concentration ratio allowed to control the type of the resulting mustard oxidates. As the pH of the reaction medium was increased, the reaction of elimination of hydrogen chloride from mustard oxidates becomes more and more intensive

  4. Healthy Dietary Patterns and Oxidative Stress as Measured by Fluorescent Oxidation Products in Nurses’ Health Study

    Directory of Open Access Journals (Sweden)

    Seungyoun Jung

    2016-09-01

    Full Text Available Healthy diets may lower oxidative stress and risk of chronic diseases. However, no previous studies examined associations between diet and fluorescent oxidation products (FlOP, a global marker of oxidative stress. We evaluated associations between healthy eating patterns (Alternative Healthy Eating Index (AHEI, Dietary Approach to Stop Hypertension (DASH, and Alternate Mediterranean Diet (aMED and FlOP, measured at three excitation/emission wavelengths (FlOP_360, FlOP_320, FlOP_400 from 2021 blood samples collected from 1688 women within the Nurses’ Health Study. AHEI, DASH, and aMED scores were significantly positively associated with FlOP_360 and FlOP_320 concentrations (p-trend ≤ 0.04, but not associated with FlOP_400. Among specific food groups that contribute to these diet scores, significantly positive associations were observed with legumes and vegetables for FlOP_360, vegetables and fruits for FlOP_320, and legumes and alcohol for FlOP_400. Inverse associations were observed with nuts, sweets or desserts, and olive oil for FlOP_360, nuts for FlOP_320 and sweets or desserts for FlOP_400 (all p-trend ≤ 0.05. However, FlOP variation due to diet was small compared to overall FlOP variation. In conclusion, AHEI, DASH, and aMED scores were unexpectedly positively, but weakly, associated with FlOP_360 and FlOP_320. However, these findings should be interpreted cautiously as the determinants of FlOP concentrations are not fully understood.

  5. Healthy Dietary Patterns and Oxidative Stress as Measured by Fluorescent Oxidation Products in Nurses' Health Study.

    Science.gov (United States)

    Jung, Seungyoun; Smith-Warner, Stephanie A; Willett, Walter C; Wang, Molin; Wu, Tianying; Jensen, Majken; Hankinson, Susan E; Eliassen, A Heather

    2016-09-21

    Healthy diets may lower oxidative stress and risk of chronic diseases. However, no previous studies examined associations between diet and fluorescent oxidation products (FlOP), a global marker of oxidative stress. We evaluated associations between healthy eating patterns (Alternative Healthy Eating Index (AHEI), Dietary Approach to Stop Hypertension (DASH), and Alternate Mediterranean Diet (aMED)) and FlOP, measured at three excitation/emission wavelengths (FlOP_360, FlOP_320, FlOP_400) from 2021 blood samples collected from 1688 women within the Nurses' Health Study. AHEI, DASH, and aMED scores were significantly positively associated with FlOP_360 and FlOP_320 concentrations ( p -trend ≤ 0.04), but not associated with FlOP_400. Among specific food groups that contribute to these diet scores, significantly positive associations were observed with legumes and vegetables for FlOP_360, vegetables and fruits for FlOP_320, and legumes and alcohol for FlOP_400. Inverse associations were observed with nuts, sweets or desserts, and olive oil for FlOP_360, nuts for FlOP_320 and sweets or desserts for FlOP_400 (all p -trend ≤ 0.05). However, FlOP variation due to diet was small compared to overall FlOP variation. In conclusion, AHEI, DASH, and aMED scores were unexpectedly positively, but weakly, associated with FlOP_360 and FlOP_320. However, these findings should be interpreted cautiously as the determinants of FlOP concentrations are not fully understood.

  6. Thermochemical study of MoS2 oxidation

    International Nuclear Information System (INIS)

    Filimonov, D.S.; Topor, N.D.; Kesler, Ya.A.

    1990-01-01

    Thermochemical studies of oxidation processes of metallic molybdenum, sulfur, molybdenum disulfide under different conditions in microcalorimeter are conducted. Values of thermal effects which are used to calculate standard formation enthalpy of MoS 2 and which correlate well are obtained. Δ f H 0 (MoS 2 ,298.15 K) recommended value constitutes (-223.0±16.7) kJ/mol

  7. Study of comportment of trioctylphosphine oxide by coat slight chromatography

    International Nuclear Information System (INIS)

    Meddour, Laaldja; Azzouz Abdelkrim

    1996-04-01

    The synthesis and characterisation process of the extractant agent 'Trioctylphosphine oxide' (TOPO) are not very developped in the literature. However, in order to identify this agent (TOPO) in its synthesis process, we attempt several analysis methods. The coat slight chromatography proves the simple and accessible method, that explains the choice of this study. In the present work, we have analysed the TOPO by coat slight chromatography with the intention of finding a better solvent

  8. Glancing angle x-ray studies of oxide films

    International Nuclear Information System (INIS)

    Davenport, A.J.; Isaacs, H.S.

    1989-01-01

    High brightness synchrotron radiation incident at glancing angles has been used to study inhibiting species present in low concentrations in oxide films on aluminum. Glancing incident angle fluorescence measurements give surface-sensitive information on the valence state of elements from the shape of the x-ray absorption edge. Angle-resolved measurements show the depth distribution of the species present. 15 refs., 4 figs

  9. X-ray Absorption Study of Graphene Oxide and Transition Metal Oxide Nanocomposites

    OpenAIRE

    Gandhiraman, Ram P.; Nordlund, Dennis; Javier, Cristina; Koehne, Jessica E.; Chen, Bin; Meyyappan, M.

    2014-01-01

    The surface properties of the electrode materials play a crucial role in determining the performance and efficiency of energy storage devices. Graphene oxide and nanostructures of 3d transition metal oxides were synthesized for construction of electrodes in supercapacitors, and the electronic structure and oxidation states were probed using near-edge X-ray absorption fine structure. Understanding the chemistry of graphene oxide would provide valuable insight into its reactivity and properties...

  10. Studies on yttrium oxide coatings for corrosion protection against molten uranium

    International Nuclear Information System (INIS)

    Chakravarthy, Y.; Bhandari, Subhankar; Pragatheeswaran; Thiyagarajan, T.K.; Ananthapadmanabhan, P.V.; Das, A.K.; Kumar, Jay; Kutty, T.R.G.

    2012-01-01

    Yttrium oxide is resistant to corrosion by molten uranium and its alloys. Yttrium oxide is recommended as a protective oxide layer on graphite and metal components used for melting and processing uranium and its alloys. This paper presents studies on the efficacy of plasma sprayed yttrium oxide coatings for barrier applications against molten uranium

  11. Photoluminescence study on amino functionalized dysprosium oxide-zinc oxide composite bifunctional nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Aswathy; Praveen, G.L; Abha, K.; Lekha, G.M [Department of Chemistry, University of Kerala, Kariavattom, Kerala 695581 (India); George, Sony, E-mail: emailtosony@gmail.com [Department of Chemistry, University of Kerala, Kariavattom, Kerala 695581 (India)

    2012-08-15

    An organic dispersion of 9-15 nm size stable dysprosium oxide incorporated zinc oxide nanocomposites exhibiting luminescence in the visible region has been synthesised by a wet chemical precipitation technique at room temperature. Tetraethoxysilane TEOS [(C{sub 2}H{sub 5}O){sub 4}Si], (3-aminopropyl) trimethoxysilane (APTS) and a 1:1 mixture of TEOS-APTS have been used as capping agents to control the particle size as well as to achieve uniform dispersion of composite nanoparticles in methanol medium. X-ray diffractometer (XRD) analysis reveals the formation phase of amino-functionalised colloidal dysprosium oxide incorporated ZnO composite nanoparticles to be of zincite structure. The Transmission Electron Microscopy (TEM) images show that the particles are spheroids in shape, having average crystalline sizes ranging from 9 to 15 nm. The photoluminescence (PL) observed in these composites has been attributed to the presence of near band edge excitonic emission and existence of defect centres. The time correlated single photon counting studies of the composite nanoparticles exhibited three decay pathways. The enhanced PL emission intensity of solid state fluorescence spectra of samples is attributed to the absence of vibrational relaxation process. - Highlights: Black-Right-Pointing-Pointer Nano-composites are synthesised using a one step wet chemical precipitation method. Black-Right-Pointing-Pointer A significant fluorescence life time of 8.25 ns is obtained for the nano-composite. Black-Right-Pointing-Pointer Nano-composite particles exhibited pale yellow fluorescence rather than blue. Black-Right-Pointing-Pointer Vibrational cascade free enhanced fluorescence is obtained for the dry sample.

  12. Combinatorial study of zinc tin oxide thin-film transistors

    Science.gov (United States)

    McDowell, M. G.; Sanderson, R. J.; Hill, I. G.

    2008-01-01

    Groups of thin-film transistors using a zinc tin oxide semiconductor layer have been fabricated via a combinatorial rf sputtering technique. The ZnO :SnO2 ratio of the film varies as a function of position on the sample, from pure ZnO to SnO2, allowing for a study of zinc tin oxide transistor performance as a function of channel stoichiometry. The devices were found to have mobilities ranging from 2to12cm2/Vs, with two peaks in mobility in devices at ZnO fractions of 0.80±0.03 and 0.25±0.05, and on/off ratios as high as 107. Transistors composed predominantly of SnO2 were found to exhibit light sensitivity which affected both the on/off ratios and threshold voltages of these devices.

  13. Study of oxidation stability of Jatropha curcas biodiesel/ diesel blends

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Siddharth; Sharma, M.P. [Biofuel Research Laboratory, Alternate Hydro Energy Centre, Indian Institute of Technology Roorkee, Uttarakhand- 247667 (India)

    2011-07-01

    Biodiesel production is undergoing rapid technological reforms in industries and academia. This has become more obvious and relevant since the recent increase in the petroleum prices and the growing awareness relating to the environmental consequences of the fuel overdependency. However, the possibilities of production of biodiesel from edible oil resources in India is almost impossible, as primary need is to first meet the demand of edible oil that is already imported therefore it is essential to explore non-edible seed oils, like Jatropha curcas and Pongamia as biodiesel raw materials. The oxidation stability of biodiesel from Jatropha curcas oil is very poor. Therefore the aim of the present paper is to study the oxidation stability of Jatropha curcas biodiesel/ diesel blend. Also the effectiveness of various antioxidants is checked with respect to various blends of biodiesel with diesel.

  14. Studies on Thermal Oxidation Stability of Aviation Lubricating Oils

    Directory of Open Access Journals (Sweden)

    Wu Nan

    2017-01-01

    Full Text Available Simulating the operating condition of aviation engine via autoclave experiment of high temperature and pressure, we studied the physic-chemical property of poly-α-olefin base oil samples mixed with antioxidants of 2,6-di-tert-butyl-4-methylphenol and p,p’-diisooctyl diphenylamine at different temperature. The mechanism of degradation of PAO aviation lubricating oil was analyzed according to the oxidized products by modern analytical instruments. The results showed that the aviation lubricating oil produced a large number of low molecule compounds while increasing the temperature, and resulted in the viscosity decreasing and acid value increasing which indicated that the thermal oxidation of the oil sample underwent a radical process.

  15. Pulse radiolysis study of one electron oxidation of riboflavin

    International Nuclear Information System (INIS)

    Kishore, K.; Moorthy, P.N.; Guha, S.N.

    1991-01-01

    One electron oxidation of riboflavin (Rf) has been studied using various oxidising species such as Cl 2 -. , SO 4 -. and OH radicals. The transient species produced by the reaction of SO 4 -. with riboflavin gave spectra with λ m at 680 and 640 nm at pHs 4 and 7.1 respectively with a pK a at ∼ 6. Cl 2 -. radicals reacted with riboflavin to give a transient spectrum with λ m at 570 nm. The possibility of two sites viz. C-8 methyl group and the extended π-ring system of the molecule for oxidation reaction are discussed. The reaction of Cl 2 -. with riboflavin is an equilibrium from which the redox potential for the Rf +. /Rf couple has been evaluated to be 2.28 V vs NHE. OH radicals reacted with riboflavin to give a transient spectrum attributable to a mixture of species produced by addition or abstraction reactions. (author)

  16. Study of Plasma Electrolytic Oxidation Coatings on Aluminum Composites

    Directory of Open Access Journals (Sweden)

    Leonid Agureev

    2018-06-01

    Full Text Available Coatings, with a thickness of up to 75 µm, were formed by plasma electrolytic oxidation (PEO under the alternating current electrical mode in a silicate-alkaline electrolyte on aluminum composites without additives and alloyed with copper (1–4.5%. The coatings’ structure was analyzed by scanning electron microscopy, X-ray microanalysis, X-ray photoelectron spectroscopy, nuclear backscattering spectrometry, and XRD analysis. The coatings formed for 60 min were characterized by excessive aluminum content and the presence of low-temperature modifications of alumina γ-Al2O3 and η-Al2O3. The coatings formed for 180 min additionally contained high-temperature corundum α-Al2O3, and aluminum inclusions were absent. The electrochemical behavior of coated composites and uncoated ones in 3% NaCl was studied. Alloyage of aluminum composites with copper increased the corrosion current density. Plasma electrolytic oxidation reduced it several times.

  17. Deodorization optimization of Camelina sativa oil: Oxidative and sensory studies

    DEFF Research Database (Denmark)

    Hrastar, Robert; Cheong, Ling‐Zhi; Xu, Xuebing

    2011-01-01

    [peroxide value (PV), p‐anisidine value (p‐AV), γ‐tocopherol (γ‐T) and oxidative stability (OS)]. Additionally, sensory evaluation was performed. RSM analysis showed a significant effect of deodorization temperature and to a lesser extent, deodorization steam flow and time on removal of oxidative compounds....... In the present study RSM and principal component analysis (PCA) were used to optimize bench‐scale deodorization of CO. Mathematical models were generated through multiple regressions with backward elimination, describing the effects of process parameters (temperature, steam flow, time) on oil quality indicators......, flavour and odour. PCA of chemical and sensory results showed that deodorization temperature affected the sensory properties in the samples. The best conditions for removing undesirable flavour and odour were achieved by using a deodorization temperature of 195–210°C....

  18. Lithium ion behavior in lithium oxide by neutron scattering studies

    International Nuclear Information System (INIS)

    Ishii, Yoshinobu; Morii, Yukio; Katano, Susumu; Watanabe, Hitoshi; Funahashi, Satoru; Ohno, Hideo; Nicklow, R.M.

    1992-01-01

    Lithium ion behavior in lithium oxide, Li 2 O, was studied in the temperature range from 293 K to 1120 K by the High-Resolution Powder Diffractometer (HRPD) installed in the JRR-3M. The diffraction patterns were analyzed with the RIETAN program. At room temperature, the thermal parameters related to the mean square of the amplitude of vibration of the lithium and the oxygen ions were 6 x 10 -21 m 2 and 4 x 10 -21 m 2 , respectively. AT 1120 K the thermal parameter of the lithium ion was 34 x 10 -21 m 2 . On the other hand, the parameter of the oxygen ion was 16 x 10 -21 m 2 . Inelastic neutron scattering studies for the lithium oxide single crystal were also carried out on the triple-axis neutron spectrometers installed at the JRR-2 and the HFIR. Although the value of a phonon energy of a transverse acoustic mode (Σ 3 ) at zone boundary was 30.6 meV at room temperature, this value was decreased to 25.1 meV at 700 K. This large softening was caused by anharmonicity of the crystal potential of lithium oxide. (author)

  19. Study of the tunnelling initiated leakage current through the carbon nanotube embedded gate oxide in metal oxide semiconductor structures

    International Nuclear Information System (INIS)

    Chakraborty, Gargi; Sarkar, C K; Lu, X B; Dai, J Y

    2008-01-01

    The tunnelling currents through the gate dielectric partly embedded with semiconducting single-wall carbon nanotubes in a silicon metal-oxide-semiconductor (MOS) structure have been investigated. The application of the gate voltage to such an MOS device results in the band bending at the interface of the partly embedded oxide dielectric and the surface of the silicon, initiating tunnelling through the gate oxide responsible for the gate leakage current whenever the thickness of the oxide is scaled. A model for silicon MOS structures, where carbon nanotubes are confined in a narrow layer embedded in the gate dielectric, is proposed to investigate the direct and the Fowler-Nordheim (FN) tunnelling currents of such systems. The idea of embedding such elements in the gate oxide is to assess the possibility for charge storage for memory device applications. Comparing the FN tunnelling onset voltage between the pure gate oxide and the gate oxide embedded with carbon nanotubes, it is found that the onset voltage decreases with the introduction of the nanotubes. The direct tunnelling current has also been studied at very low gate bias, for the thin oxide MOS structure which plays an important role in scaling down the MOS transistors. The FN tunnelling current has also been studied with varying nanotube diameter

  20. First principles studies of complex oxide surfaces and interfaces

    International Nuclear Information System (INIS)

    Noguera, Claudine; Finocchi, Fabio; Goniakowski, Jacek

    2004-01-01

    Oxides enter our everyday life and exhibit an impressive variety of physical and chemical properties. The understanding of their behaviour, which is often determined by the electronic and atomic structures of their surfaces and interfaces, is a key question in many fields, such as geology, environmental chemistry, catalysis, thermal coatings, microelectronics, and bioengineering. In the last decade, first principles methods, mainly those based on the density functional theory, have been frequently applied to study complex oxide surfaces and interfaces, complementing the experimental observations. In this work, we discuss some of these contributions, with emphasis on several issues that are especially important when dealing with oxides: the local electronic structure at interfaces, and its connection with chemical reactivity; the charge redistribution and the bonding variations, in relation to screening properties; and the possibility of bridging the gap between model and real systems by taking into account the chemical environments and the effect of finite temperatures, and by performing simulations on systems of an adequate (large) size

  1. Study on antimony oxide self-assembled inside HZSM-5

    International Nuclear Information System (INIS)

    Li Bin; Li Shijie; Wang Yingxia; Li Neng; Liu Xiyao; Lin Bingxiong

    2005-01-01

    Sb/ZSM-5 was obtained by solid-state reaction with the mixture of Sb 2 O 3 and zeolite HZSM-5 under a dry nitrogen flow at 773K. Characterization of the treated zeolite was undertaken with XRD, 27 Al MAS NMR, BET, TGA and FT-IR. The results revealed that part of the antimony oxides migrated into the channels of zeolite, and decreased the Bronsted acid sites in Sb/ZSM-5 remarkably. The other part of antimony oxides together with the amorphous alumino-silicate in the products distributed on the external surface of zeolite ZSM-5 and modified it, while the framework of ZSM-5 in crystal phase was retained. The structure of occluded antimony oxide inside the channels of ZSM-5 was studied by XRD Rietveld method. The result showed that their structure can be described as a chain of non-perfect [Sb 5 O 5 (H 2 O) 2 ] n 5n+ , which is parallel to the straight channel of ZSM-5. There is about 0.6 [Sb 5 O 5 (H 2 O) 2 ] 5+ unit in every cell of the ZSM-5 on an average

  2. Study of uranium oxidation states in geological material.

    Science.gov (United States)

    Pidchenko, I; Salminen-Paatero, S; Rothe, J; Suksi, J

    2013-10-01

    A wet chemical method to determine uranium (U) oxidation states in geological material has been developed and tested. The problem faced in oxidation state determinations with wet chemical methods is that U redox state may change when extracted from the sample material, thereby leading to erroneous results. In order to quantify and monitor U redox behavior during the acidic extraction in the procedure, an analysis of added isotopic redox tracers, (236)U(VI) and (232)U(IV), and of variations in natural uranium isotope ratio ((234)U/(238)U) of indigenous U(IV) and U(VI) fractions was performed. Two sample materials with varying redox activity, U bearing rock and U-rich clayey lignite sediment, were used for the tests. The Fe(II)/Fe(III) redox-pair of the mineral phases was postulated as a potentially disturbing redox agent. The impact of Fe(III) on U was studied by reducing Fe(III) with ascorbic acid, which was added to the extraction solution. We observed that ascorbic acid protected most of the U from oxidation. The measured (234)U/(238)U ratio in U(IV) and U(VI) fractions in the sediment samples provided a unique tool to quantify U oxidation caused by Fe(III). Annealing (sample heating) to temperatures above 500 °C was supposed to heal ionizing radiation induced defects in the material that can disturb U redox state during extraction. Good agreement between two independent methods was obtained for DL-1a material: an average 38% of U(IV) determined by redox tracer corrected wet chemistry and 45% for XANES. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Study of the pelletizing process zirconium oxide and zircon sand

    International Nuclear Information System (INIS)

    Seo, E.S.M.; Paschoal, J.O.A.; Acevedo, M.T.P.

    1990-12-01

    The study of the process to obtain zirconium tetrachloride under development at IPEN, can be divide into two steps: pelletizing and chlorination. Pelletizing is an important step in the overall process as it facilitates greater contact between the particles and permits the production of pellets with dimensional uniformity and mechanical strength. In this paper, the results of the study of pelletizing zirconium oxide and zircon sand are presented. The influence of some variables related to the process and the equipment on the physical characteristics of the pellets are discussed. (author)

  4. Kinetic studies of sulfide mineral oxidation and xanthate adsorption

    Science.gov (United States)

    Mendiratta, Neeraj K.

    2000-10-01

    Sulfide minerals are a major source of metals; however, certain sulfide minerals, such as pyrite and pyrrhotite, are less desirable. Froth flotation is a commonly used separation technique, which requires the use of several reagents to float and depress different sulfide minerals. Xanthate, a thiol collector, has gained immense usage in sulfide minerals flotation. However, some sulfides are naturally hydrophobic and may float without a collector. Iron sulfides, such as pyrite and pyrrhotite, are few of the most abundant minerals, yet economically insignificant. Their existence with other sulfide minerals leads to an inefficient separation process as well as environmental problems, such as acid mine drainage during mining and processing and SO 2 emissions during smelting process. A part of the present study is focused on understanding their behavior, which leads to undesired flotation and difficulties in separation. The major reasons for the undesired flotation are attributed to the collectorless hydrophobicity and the activation with heavy metal ions. To better understand the collectorless hydrophobicity of pyrite, Electrochemical Impedance Spectroscopy (EIS) of freshly fractured pyrite electrodes was used to study the oxidation and reduction of the mineral. The EIS results showed that the rate of reaction increases with oxidation and reduction. At moderate oxidizing potentials, the rate of reaction is too slow to replenish hydrophilic iron species leaving hydrophobic sulfur species on the surface. However, at higher potentials, iron species are replaced fast enough to depress its flotation. Effects of pH and polishing were also explored using EIS. Besides collectorless hydrophobicity, the activation of pyrrhotite with nickel ions and interaction with xanthate ions makes the separation more difficult. DETA and SO2 are commonly used as pyrrhotite depressants; however, the mechanism is not very well understood. Contact angle measurements, cyclic voltammetry and Tafel

  5. Ab initio study of perovskite type oxide materials for solid oxide fuel cells

    Science.gov (United States)

    Lee, Yueh-Lin

    2011-12-01

    Perovskite type oxides form a family of materials of significant interest for cathodes and electrolytes of solid oxide fuel cells (SOFCs). These perovskites not only are active catalysts for surface oxygen reduction (OR) reactions but also allow incorporating the spilt oxygen monomers into their bulk, an unusual and poorly understood catalytic mechanism that couples surface and bulk properties. The OR mechanisms can be influenced strongly by defects in perovskite oxides, composition, and surface defect structures. This thesis work initiates a first step in developing a general strategy based on first-principles calculations for detailed control of oxygen vacancy content, transport rates of surface and bulk oxygen species, and surface/interfacial reaction kinetics. Ab initio density functional theory methods are used to model properties relevant for the OR reactions on SOFC cathodes. Three main research thrusts, which focus on bulk defect chemistry, surface defect structures and surface energetics, and surface catalytic properties, are carried to investigate different level of material chemistry for improved understanding of key physics/factors that govern SOFC cathode OR activity. In the study of bulk defect chemistry, an ab initio based defect model is developed for modeling defect chemistry of LaMnO 3 under SOFC conditions. The model suggests an important role for defect interactions, which are typically excluded in previous defect models. In the study of surface defect structures and surface energetics, it is shown that defect energies change dramatically (1˜2 eV lower) from bulk values near surfaces. Based on the existing bulk defect model with the calculated ab initio surface defect energetics, we predict the (001) MnO 2 surface oxygen vacancy concentration of (La0.9Sr0.1 )MnO3 is about 5˜6 order magnitude higher than that of the bulk under typical SOFC conditions. Finally, for surface catalytic properties, we show that area specific resistance, oxygen

  6. One-electron oxidations of ferrocenes: a pulse radiolysis study

    International Nuclear Information System (INIS)

    Faraggi, Moshe; Weinraub, Dany; Broitman, Federico; DeFelippis, M.R.; Klapper, M.H.

    1988-01-01

    Using the pulse radiolysis technique we have studied the oxidation by various inorganic radicals of four water soluble ferrocene derivatives, hydroxyethyl, dimethylaminomethyl, monocarboxylic acid and dicarboxylic acid. We report the second order rate constants for these reactions, the stabilities and spectral properties of the ferrocinium products, and the electrochemically determined ferrocinium/ferrocene redox potentials. We also present preliminary estimates of tyrosine and tryptophan radical redox potentials obtained with the dicarboxylic acid ferrocene derivative as reference, and we discuss the relationship between redox potential differences and the reactivities of the ferrocenes with the inorganic radicals. (author)

  7. Study on the serum oxidative stress status in silicosis patients

    African Journals Online (AJOL)

    Administrator

    2011-09-07

    Sep 7, 2011 ... oxidative stress parameters were investigated in silicosis patients and controls group. 128 silicosis ... to help clinicians to further delineate the role of oxidative- stress .... in age, working duration smoking, total cholesterol, ALT,.

  8. [Studies on the oxidation reaction of octanol-2 with nitric acid by infrared spectroscopy].

    Science.gov (United States)

    Zhang, G; Zhao, G; Wang, Y; Zhang, Q; Zhang, S; Lu, F

    1998-04-01

    In this paper, the reaction process of oxidation of octanol-2 with nitric acid has been studied by IR spectroscopy. It is found that the main components of non-sapoifiable matter are different in different oxidation degrees. The relation between oxidation products and the amount of nitric acid are investigated,the reaction mechanism has also been studied. Experimental results show that the oxidation process of octanol-2 is as follows: first, octanol-2 is oxidated to octanone-2, or to nitrate, nitrite and nitrile copmpounds, then these compounds are reoxidated to caproic acid in the meantime some by-products, such as valeric, enanthic acids are also found in oxidated products.

  9. An ab initio study of plutonium oxides surfaces

    International Nuclear Information System (INIS)

    Jomard, G.; Bottin, F.; Amadon, B.

    2007-01-01

    By means of first-principles calculations, we have studied the atomic structure as well as the thermodynamic stability of various plutonium dioxide surfaces in function of their environment (in terms of oxygen partial pressure and temperature). All these simulations have been performed with the ABINIT code. It is well known that DFT fails to describe correctly plutonium-based materials since 5f electrons in such systems are strongly correlated. In order to go beyond DFT, we have treated PuO 2 and β-Pu 2 O 3 in a DFT+U framework. We show that the couple of parameters (U,J) that works well for pure Pu is also well designed for describing ground state (GS) properties of these two oxides. The major improvement with respect with DFT is that we are able to predict an insulating GS in agreement with experiments. The presence of a gap in the DOS (Density of States) of plutonium oxides should play a significant role in the predicted surface reactivity. However, performing DFT+U calculations on surfaces of plutonium oxide from scratch was too ambitious. That is why we decided, as a first step, to study the stability of the (100), (110) and (111) surfaces of PuO 2 in a DFT-GGA framework. For each of these orientations, we considered various terminations. These ab initio results have been introduced in a thermodynamic model which allows us to predict the relative stability of the different terminations as a function of temperature and oxygen partial pressure (p O 2 ). We conclude that at room temperature and for p O 2 ∼10 atm., the polar O 2 -(100) termination is favoured. The stabilization of such a polar stoichiometric surface is surprising and should be confirmed by DFT+U calculations before any final conclusion. (authors)

  10. Study on cobalt oxide; Sanka kobaruto ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-11-28

    This is No.91 report of National Institute for Research in Inorganic Materials, concerning cobalt oxide. For the growth of single crystal by the Czochralski method, shape of interface and contamination of impurities are affected by the convection of molten liquid in the atmosphere. Various oxides besides CoO were investigated. Solid solutions of Cr2O3 and Al2O3 into CoO were also studied. Non-linear optic and dielectric properties of single crystals, such as Ba2NaNb5O15 and LiNbO3, were examined. It was considered that the positive electron having positive electric charge can be used for the study on the negative electric charge defect in materials. However, the positive electron itself is rare, which results in the too low efficiency of measurement. Efficiency improvement of 50 times was achieved by introducing a high performance 2D position detector, which was still low efficiency of one-hundredth compared with photoelectron spectroscopy. It was found that the aggregation structure of positive ion defects in CoO is a misunderstanding of phenomenon caused by the electronic state in bulk crystals. As a result of the study on the optical properties of f-electron transition metals, transparent ceramics with addition of various rare earth ions were described. 162 refs., 106 figs., 14 tabs.

  11. Study of coal oxidation by charged particle activation analysis

    International Nuclear Information System (INIS)

    Schlyer, D.J.; Wolf, A.P.

    1980-01-01

    It has been possible, using the technique of changed particle activation analysis, to follow the time course of the oxidation of coal exposed to air. The kinetics have been studied and seem to be consistent with a rapid initial uptake of oxygen containing molecules followed by slow diffusion into the surface of the coal particles. In this latter regard a study has been undertaken to study the depth profile of the oxygen into the coal particle surface. The depth of penetration of the activating particle is determined by the incident energy and therefore, by comparison to the appropriate standards, the depth profile may be determined either by varying the incident energy or by varying the particle size. Both approaches have been used and give consistent results. The depth to which a significant amount of oxygen penetrates varies from about 3 μm for very high rank coals to about 20 μm for low rank coals. This diffusion depth seems to be related to the porosity of the coals. A model for the low temperature air oxidation of coal has been developed to explain the results from the above mentioned experiments

  12. XPS study of vanadium surface oxidation by oxygen ion bombardment

    Czech Academy of Sciences Publication Activity Database

    Alov, N.; Kutsko, D.; Spirovová, Ilona; Bastl, Zdeněk

    2006-01-01

    Roč. 600, č. 8 (2006), s. 1628-1631 ISSN 0039-6028 R&D Projects: GA ČR GA104/04/0467 Institutional research plan: CEZ:AV0Z40400503 Keywords : vanadium oxide * oxide film * ion-beam oxidation * X-ray photoelectron spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.880, year: 2006

  13. The stability study of myristyl dimethyl amine oxide as an amphoteric ...

    African Journals Online (AJOL)

    The stability study of myristyl dimethyl amine oxide as an amphoteric surfactant in strong oxidant media containing 5 % m/m sodium hypochlorite through measurement of decomposing rate using high performance liquid chromatography and two phase titration.

  14. Studies of colossal magnetoresistive oxides with radioactive isotopes

    CERN Document Server

    CERN. Geneva. ISOLDE and Neutron Time-of-Flight Experiments Committee; Amaral, V S; Araújo, J P; Butz, T; Correia, J G; Dubourdieu, C; Habermeier, H U; Lourenço, A A; Marques, J G; Da Silva, M F A; Senateur, J P; Soares, J C; Sousa, J B; Suryan, R; Tokura, Y; Tavares, P B; Tomioka, Y; Tröger, W; Vantomme, A; Vieira, J M; Wahl, U; Weiss, F P; INTC

    2000-01-01

    We propose to study Colossal Magnetoresistive (CMR) oxides with several nuclear techniques, which use radioactive elements at ISOLDE. Our aim is to provide local and element selective information on some of the doping mechanisms that rule electronic interactions and magnetoresistance, in a complementary way to the use of conventional characterisation techniques. Three main topics are proposed: \\\\ \\\\ a) Studies of local [charge and] structural modifications in antiferromagnetic LaMnO$_{3+ \\delta}$ and La$_{1-x}$R$_{x}$MnO$_{3}$ with R=Ca and Cd, doped ferromagnetic systems with competing interactions: - research on the lattice site and electronic characterisation of the doping element. \\\\ \\\\ b) Studies of self doped La$_{x}$R$_{1-x}$MnO$_{3+\\delta}$ systems, with oxygen and cation non-stoichiometry: -learning the role of defects in the optimisation of magnetoresistive properties. \\\\ \\\\ c) Probing the disorder and quenched random field effects in the vicinity of the charge or orbital Ordered/Ferromagnetic phase...

  15. Studies of Colossal Magnetoresistive Oxides with Radioactive Isotopes

    CERN Multimedia

    2002-01-01

    We propose to study Colossal Magnetoresistive (CMR) oxides with several nuclear techniques, which use radioactive elements at ISOLDE. Our aim is to provide local and element selective information on some of the doping mechanisms that rule electronic interactions and magneto- resistance, in a complementary way to the use of conventional characterisation techniques. Three main topics are proposed: \\\\ \\\\ a) Studies of local [charge and] structural modifications in antiferromagnetic LaMnO$_{3+\\delta}$ and La$_{1-x}$R$_{x}$MnO$_{3}$ with R=Ca and Cd, doped ferromagnetic systems with competing interactions: - research on the lattice site and electronic characterisation of the doping element. \\\\ \\\\ b) Studies of self doped La$_{x}$R$_{1-x}$MnO$_{3+\\delta}$ systems, with oxygen and cation non- stoichiometry: - learning the role of defects in the optimisation of magnetoresestive properties. \\\\ \\\\ c) Probing the disorder and quenched random field effects in the vicinity of the charge or orbital Ordered/Ferromagnetic p...

  16. A study on the oxidation behavior of uranium

    International Nuclear Information System (INIS)

    Kim, Tae Kook; Kang, Kweon Ho; Kim, Kil Jeang; Kang, Il Sik; Jung, Kyung Whan

    1998-03-01

    When storing depleted uranium wastes, careful handling is required due to their very high oxidation rates. To determine the oxidation mechanism and oxidation rate of depleted uranium wastes, the most important factors to be considered in their treatment, an experiment was carried out by varying the heating rates of the Air-Controlled Oxidizer. The experiment, showed that depleted uranium wastes are pulverized after complete oxidation because of the density difference and then converted to UO 2 , U 3 O 7 , U 3 O 8 . The grain size of pulverized powder decrease with increased temperature. (author). 30 refs., 5 tabs., 28 figs

  17. Study of the oxidation kinetics of the MA 956 superalloy

    International Nuclear Information System (INIS)

    Garcia-Alonso, M.C.; Gonzalez-Carrasco, J.L.; Escudero, M.L.

    1998-01-01

    This work deals with the oxidation kinetics of the MA 956 superalloy in the temperature range of 800-1,200 degree centigree for up to 200 h exposure. During oxidation the alloy develops a fine, compact and very well adhered α-alumina layer, the thickness of which increases with increasing time and temperature. The oxidation kinetics obeys a sub parabolic type behaviour. The scale growth seems to occur by two different oxidation mechanisms; above 1,050 degree centigree, the oxidation process would be controlled by α-alumina, and below 900 degree centigree by γ-alumina. (Author) 17 refs

  18. Oxide nanomaterials: synthetic developments, mechanistic studies, and technological innovations.

    Science.gov (United States)

    Patzke, Greta R; Zhou, Ying; Kontic, Roman; Conrad, Franziska

    2011-01-24

    Oxide nanomaterials are indispensable for nanotechnological innovations, because they combine an infinite variety of structural motifs and properties with manifold morphological features. Given that new oxide materials are almost reported on a daily basis, considerable synthetic and technological work remains to be done to fully exploit this ever increasing family of compounds for innovative nano-applications. This calls for reliable and scalable preparative approaches to oxide nanomaterials and their development remains a challenge for many complex nanostructured oxides. Oxide nanomaterials with special physicochemical features and unusual morphologies are still difficult to access by classic synthetic pathways. The limitless options for creating nano-oxide building blocks open up new technological perspectives with the potential to revolutionize areas ranging from data processing to biocatalysis. Oxide nanotechnology of the 21st century thus needs a strong interplay of preparative creativity, analytical skills, and new ideas for synergistic implementations. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Diethyl Phthalate Causes Oxidative Stress: An in Vitro Study

    Directory of Open Access Journals (Sweden)

    Heena Prajapati

    2014-03-01

    Full Text Available Background: Phthalates are a group of multifunctional chemicals. Diethyl phthalate (DEP is one of the most frequently used phthalates in solvents and fixatives for numerous industrial products. Method: The present experiment was designed to assess oxidative stress, if any, caused by diethyl phthalate. For this the homogenates of liver and kidney were treated with different concentrations ( 10-40 µg/mL of DEP. 10% liver and kidney homogenates were prepared in phosphate buffered saline and used for estimation of lipid peroxidation.In final step lipid peroxidation and total protein content were analyzed. Results: The result revealed significant and dose - dependent increase in lipid peroxidation, whereas protein content reduced significantly. Maximum increase in LPO and decrease in protein content was observed at 40 µg/mL of DEP concentration. Conclusion: From this study, it can be concluded that different concentrations of DEP leads to dose- dependent significant increase in lipid peroxidation and decrease protein content.So at the different concentration of DEP cause oxidative stress.

  20. Molecular beam studies of oxide reduction by atomic hydrogen

    International Nuclear Information System (INIS)

    Olander, D.R.

    1978-01-01

    The graphite and oxide internals of a CTR are susceptible to chemical corrosion as well as to physical degradation by high-energy particles. Reactions of thermal atomic hydrogen with oxides are being studied. The hydrogen used is at thermal energy (0.22 eV). Typical data are reported for the H/UO 2 system. The reaction probability is plotted as a function of solid temperature at fixed beam intensity and moculation frequency. The reaction probability increases from low temperature to a high-temperature plateau at about 1300 0 C. Here the reaction rate is limited solely by the sticking probability of H on the surface; about one in seven of the incident atoms is chemisorbed by the surface and ultimately returns to the gas phase as water vapor. A reaction model comprising sticking, recombination to H 2 , solution and diffusion of H in the bulk of the UO 2 , surface reaction of adsorbed H with lattice oxygen atoms to produce the hydroxyl radical, and production of water is constructed. The rate constants for the elementary steps in the mechanism are tabulated. 2 figures, 2 tables

  1. Enhanced piezoelectricity of monolayer phosphorene oxides: a theoretical study.

    Science.gov (United States)

    Yin, Huabing; Zheng, Guang-Ping; Gao, Jingwei; Wang, Yuanxu; Ma, Yuchen

    2017-10-18

    Two-dimensional (2D) piezoelectric materials have potential applications in miniaturized sensors and energy conversion devices. In this work, using first-principles simulations at different scales, we systematically study the electronic structures and piezoelectricity of a series of 2D monolayer phosphorene oxides (POs). Our calculations show that the monolayer POs have tunable band gaps along with remarkable piezoelectric properties. The calculated piezoelectric coefficient d 11 of 54 pm V -1 in POs is much larger than those of 2D transition metal dichalcogenide monolayers and the widely used bulk α-quartz and AlN, and almost reaches the level of the piezoelectric effect in recently discovered 2D GeS. Furthermore, two other considerable piezoelectric coefficients, i.e., d 31 and d 26 with values of -10 pm V -1 and 21 pm V -1 , respectively, are predicted in some monolayer POs. We also examine the correlation between the piezoelectric coefficients and energy stability. The enhancement of piezoelectricity for monolayer phosphorene by oxidation will broaden the applications of phosphorene and phosphorene derivatives in nano-sized electronic and piezotronic devices.

  2. Experimental studies of oxidic molten corium-vessel steel interaction

    International Nuclear Information System (INIS)

    Bechta, S.V.; Khabensky, V.B.; Vitol, S.A.; Krushinov, E.V.; Lopukh, D.B.; Petrov, Yu.B.; Petchenkov, A.Yu.; Kulagin, I.V.; Granovsky, V.S.; Kovtunova, S.V.; Martinov, V.V.; Gusarov, V.V.

    2001-01-01

    The experimental results of molten corium-steel specimen interaction with molten corium on the 'Rasplav-2' test facility are presented. In the experiments, cooled vessel steel specimens positioned on the molten pool bottom and uncooled ones lowered into the molten pool were tested. Interaction processes were studied for different corium compositions, melt superheating and in alternative (inert and air) overlying atmosphere. Hypotheses were put forward explaining the observed phenomena and interaction mechanisms. The studies presented in the paper were aimed at the detection of different corium-steel interaction mechanisms. Therefore certain identified phenomena are more typical of the ex-vessel localization conditions than of the in-vessel corium retention. Primarily, this can be referred to the phenomena of low-temperature molten corium-vessel steel interaction in oxidizing atmosphere

  3. Experimental studies of oxidic molten corium-vessel steel interaction

    Energy Technology Data Exchange (ETDEWEB)

    Bechta, S.V. E-mail: niti-npc@sbor.net; Khabensky, V.B.; Vitol, S.A.; Krushinov, E.V.; Lopukh, D.B.; Petrov, Yu.B.; Petchenkov, A.Yu.; Kulagin, I.V.; Granovsky, V.S.; Kovtunova, S.V.; Martinov, V.V.; Gusarov, V.V

    2001-12-01

    The experimental results of molten corium-steel specimen interaction with molten corium on the 'Rasplav-2' test facility are presented. In the experiments, cooled vessel steel specimens positioned on the molten pool bottom and uncooled ones lowered into the molten pool were tested. Interaction processes were studied for different corium compositions, melt superheating and in alternative (inert and air) overlying atmosphere. Hypotheses were put forward explaining the observed phenomena and interaction mechanisms. The studies presented in the paper were aimed at the detection of different corium-steel interaction mechanisms. Therefore certain identified phenomena are more typical of the ex-vessel localization conditions than of the in-vessel corium retention. Primarily, this can be referred to the phenomena of low-temperature molten corium-vessel steel interaction in oxidizing atmosphere.

  4. Preliminary design study of a large scale graphite oxidation loop

    International Nuclear Information System (INIS)

    Epel, L.G.; Majeski, S.J.; Schweitzer, D.G.; Sheehan, T.V.

    1979-08-01

    A preliminary design study of a large scale graphite oxidation loop was performed in order to assess feasibility and to estimate capital costs. The nominal design operates at 50 atmospheres helium and 1800 F with a graphite specimen 30 inches long and 10 inches in diameter. It was determined that a simple single walled design was not practical at this time because of a lack of commercially available thick walled high temperature alloys. Two alternative concepts, at reduced operating pressure, were investigated. Both were found to be readily fabricable to operate at 1800 F and capital cost estimates for these are included. A design concept, which is outside the scope of this study, was briefly considered

  5. Studies on the biological oxidation - The oxidation of ascorbic acid (vitamin C) in biological fluids

    OpenAIRE

    Guzmán Barrón, E. S.; Guzmán Barrón, Alberto; Klemperer, Friedrich

    2014-01-01

    Biological fluids can be divided according to their behavior toward ascorbic acid into two groups: those having an inhibitory mechanism that protects the ascorbic acid oxidation, and those lacking this mechanism. Animal fluids and some of vegetable origin (those containing dosables amounts of ascorbic acid) corresponding to the first group. Ascorbic acid is protected from oxidation in the fluids by the action of copper catalyst. Fluids from plants (those that contain very little ascorbic acid...

  6. Study on emission characteristics and reduction strategy of nitrous oxide during wastewater treatment by different processes.

    Science.gov (United States)

    Sun, Shichang; Bao, Zhiyuan; Sun, Dezhi

    2015-03-01

    Given the inexorable increase in global wastewater treatment, increasing amounts of nitrous oxide are expected to be emitted from wastewater treatment plants and released to the atmosphere. It has become imperative to study the emission and control of nitrous oxide in the various wastewater treatment processes currently in use. In the present investigation, the emission characteristics and the factors affecting the release of nitrous oxide were studied via full- and pilot-scale experiments in anoxic-oxic, sequencing batch reactor and oxidation ditch processes. We propose an optimal treatment process and relative strategy for nitrous oxide reduction. Our results show that both the bio-nitrifying and bio-denitrifying treatment units in wastewater treatment plants are the predominant sites for nitrous oxide production in each process, while the aerated treatment units are the critical sources for nitrous oxide emission. Compared with the emission of nitrous oxide from the anoxic-oxic (1.37% of N-influent) and sequencing batch reactor (2.69% of N-influent) processes, much less nitrous oxide (0.25% of N-influent) is emitted from the oxidation ditch process, which we determined as the optimal wastewater treatment process for nitrous oxide reduction, given the current technologies. Nitrous oxide emissions differed with various operating parameters. Controlling the dissolved oxygen concentration at a proper level during nitrification and denitrification and enhancing the utilization rate of organic carbon in the influent for denitrification are the two critical methods for nitrous oxide reduction in the various processes considered.

  7. Thulium oxide fuel characterization study: Part 3, Procedures

    International Nuclear Information System (INIS)

    Nelson, C.A.; Anderson, R.W.; Talbot, M.; Bierds, W.

    1970-06-01

    Procedures are presented for the following: Tm 2 O 3 -Yb 2 O 3 pseudo - binary phase diagram tests; compatibility tests; thulium-170 oxide dose rate measurements; preparation of Tm 2 O 3 wafers; SRL thulium and/or ytterbium oxide powder reprocessing for sintering; cold pressing and sintering thulium oxide wafers; preparation of thulium and/or ytterbium oxide powder via precipitation with oxalic acid, ammonium oxalate, urea and methyl oxalate; determination of the total surface area of rare earth oxide powders; determining oxygen in thulia - thulia/ytterbia for the purpose of determining metal-to-oxygen ratios; and determination of the impact resistance to fines generation of sintered rare earth oxide

  8. Study of oxidation behaviour of Zr-based bulk amorphous alloy Zr 65 ...

    Indian Academy of Sciences (India)

    The oxidation behaviour of Zr-based bulk amorphous alloy Zr65Cu17.5Ni10Al7.5 has been studied in air environment at various temperatures in the temperature range 591–684 K using a thermogravimetric analyser (TGA). The oxidation kinetics of the alloy in the amorphous phase obeys the parabolic rate law for oxidation ...

  9. Graphene oxide and reduced graphene oxide studied by the XRD, TEM and electron spectroscopy methods

    International Nuclear Information System (INIS)

    Stobinski, L.; Lesiak, B.; Malolepszy, A.; Mazurkiewicz, M.; Mierzwa, B.; Zemek, J.; Jiricek, P.; Bieloshapka, I.

    2014-01-01

    Highlights: • Graphene oxide (FL-GOc) and reduced graphene oxide (FL-RGOc): XRD, TEM, XPS, REELS. • FL-GOc: stacking nanostructure—22 × 6 nm (DxH), 0.9 nm layers separation (XRD). • FL-RGOc: stacking nanostructure—8 × 1 nm (DxH), 0.4 nm layers separation (XRD). • Reduction: oxygen group degradation, decreasing distance between graphene layers. • Number of graphene layers in stacking nanostructure: 6–7 (FL-GOc), 2–3 (FL-RGOc). - Abstract: The commercial and synthesised few-layer graphene oxide, prepared using oxidation reactions, and few-layer reduced graphene oxide samples were structurally and chemically investigated by the X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron spectroscopy methods, i.e. X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS). The commercial graphene oxide (FL-GOc) shows a stacking nanostructure of about 22 × 6 nm average diameter by height with the distance of 0.9 nm between 6-7 graphene layers, whereas the respective reduced graphene oxide (FL-RGOc)—about 8 × 1 nm average diameter by height stacking nanostructure with the distance of 0.4 nm between 2-3 graphene layers (XRD). The REELS results are consistent with those by the XRD indicating 8 (FL-GOc) and 4 layers (FL-RGOc). In graphene oxide and reduced graphene oxide prepared from the graphite the REELS indicates 8–11 and 7–10 layers. All graphene oxide samples show the C/O ratio of 2.1–2.3, 26.5–32.1 at% of C sp 3 bonds and high content of functional oxygen groups (hydroxyl—C-OH, epoxy—C-O-C, carbonyl—C=O, carboxyl—C-OOH, water) (XPS). Reduction increases the C/O ratio to 2.8–10.3, decreases C sp 3 content to 11.4–20.3 at% and also the content of C-O-C and C=O groups, accompanied by increasing content of C-OH and C-OOH groups. Formation of additional amount of water due to functional oxygen group reduction leads to layer delamination. Removing of functional oxygen groups

  10. Native oxide formation on pentagonal copper nanowires: A TEM study

    Science.gov (United States)

    Hajimammadov, Rashad; Mohl, Melinda; Kordas, Krisztian

    2018-06-01

    Hydrothermally synthesized copper nanowires were allowed to oxidize in air at room temperature and 30% constant humidity for the period of 22 days. The growth of native oxide layer was followed up by high-resolution transmission electron microscopy and diffraction to reveal and understand the kinetics of the oxidation process. Copper oxides appear in the form of differently oriented crystalline phases around the metallic core as a shell-like layer (Cu2O) and as nanoscopic islands (CuO) on the top of that. Time dependent oxide thickness data suggests that oxidation follows the field-assisted growth model at the beginning of the process, as practically immediately an oxide layer of ∼2.8 nm thickness develops on the surface. However, after this initial rapid growth, the local field attenuates and the classical parabolic diffusion limited growth plays the main role in the oxidation. Because of the single crystal facets on the side surface of penta-twinned Cu nanowires, the oxidation rate in the diffusion limited regime is lower than in polycrystalline films.

  11. Monte Carlo study of double exchange interaction in manganese oxide

    Energy Technology Data Exchange (ETDEWEB)

    Naa, Christian Fredy, E-mail: chris@cphys.fi.itb.ac.id [Physics Department, Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Jalan Ganesha 10 Bandung (Indonesia); Unité de Dynamique et Structure des Matérioux Moléculaires, Université Littoral Côte d’Opale, Maison de la Reserche Blaise Pascal 50, rue Ferdinand Buisson, Calais, France email (France); Suprijadi,, E-mail: supri@fi.itb.ac.id; Viridi, Sparisoma, E-mail: dudung@fi.itb.ac.id; Djamal, Mitra, E-mail: mitra@fi.itb.ac.id [Physics Department, Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Jalan Ganesha 10 Bandung (Indonesia); Fasquelle, Didier, E-mail: didier.fasquelle@univ-littoral.fr [Unité de Dynamique et Structure des Matérioux Moléculaires, Université Littoral Côte d’Opale, Maison de la Reserche Blaise Pascal 50, rue Ferdinand Buisson, Calais, France email (France)

    2015-09-30

    In this paper we study the magnetoresistance properties attributed by double exchange (DE) interaction in manganese oxide by Monte Carlo simulation. We construct a model based on mixed-valence Mn{sup 3+} and Mn{sup 4+} on the general system of Re{sub 2/3}Ae{sub 1/3}MnO{sub 3} in two dimensional system. The conduction mechanism is based on probability of e{sub g} electrons hopping from Mn{sup 3+} to Mn{sup 4+}. The resistivity dependence on temperature and the external magnetic field are presented and the validity with related experimental results are discussed. We use the resistivity power law to fit our data on metallic region and basic activated behavior on insulator region. On metallic region, we found our result agree well with the quantum theory of DE interaction. From general arguments, we found our simulation agree qualitatively with experimental results.

  12. Comparative DEMS study on the electrochemical oxidation of carbon blacks

    DEFF Research Database (Denmark)

    Ashton, Sean James; Arenz, Matthias

    2012-01-01

    Publication year: 2012 Source:Journal of Power Sources, Volume 217 Sean J. Ashton, Matthias Arenz The intention of the study presented here is to compare the electrochemical oxidation tendencies of a pristine Ketjen Black EC300 high surface area (HSA) carbon black, and four graphitised counterparts...... heat-treated between 2100 and 3200 °C, such as those typically used as corrosion resistant carbon (CRC) supports for polymer electrolyte membrane fuel cell (PEMFC) catalysts. A methodology combining cyclic voltammetry (CV) and differential electrochemical mass spectrometry (DEMS) is used, which allows......; however, CRC samples graphitised =2800 °C did not exhibit this same behaviour. Highlights ¿ We quantitatively determine electrooxidation of carbon support materials. ¿ We can distinguish between the total and partial electrooxidation. ¿ Non or mildly heat treated carbon forms passivating layer. ¿ Heat...

  13. Study of the discontinuous dissolution of uranium oxides

    International Nuclear Information System (INIS)

    Bueno, L.A.O.; Floh, B.; Araujo, J.A. de.

    1978-01-01

    Dissolution studies of UO 2 and U 3 O 8 particles and pellets in nitric acid were carried out to find the best flowsheet conditions for treatment of irradiated materials. All experiments were accomplished with unirradiated oxides at room-and boiling point temperature of the nitric acid solutions, the acid molarity ranging from 1 up to 12M in stoichiometric-and (100% up to 300%) excess conditions. The UO 2 (10g) and U 3 O 8 (10g) are easily dissolved (10 and 50s), respectively, at boiling point of 6M nitric acid solution. At the same conditions compacted pellets are dissolved in 29 min (U 3 O 8 =5g) and in 330 min (UO 2 =20g) [pt

  14. Piper sarmentosum increases nitric oxide production in oxidative stress: a study on human umbilical vein endothelial cells.

    Science.gov (United States)

    Ugusman, Azizah; Zakaria, Zaiton; Hui, Chua Kien; Nordin, Nor Anita Megat Mohd

    2010-07-01

    Nitric oxide produced by endothelial nitric oxide synthase (eNOS) possesses multiple anti-atherosclerotic properties. Hence, enhanced expression of eNOS and increased Nitric oxide levels may protect against the development of atherosclerosis. Piper sarmentosum is a tropical plant with antioxidant and anti-inflammatory activities. This study aimed to investigate the effects of Piper sarmentosum on the eNOS and Nitric oxide pathway in cultured human umbilical vein endothelial cells (HUVECs). HUVECS WERE DIVIDED INTO FOUR GROUPS: control, treatment with 180 microM hydrogen peroxide (H(2)O(2)), treatment with 150 microg/mL aqueous extract of Piper sarmentosum, and concomitant treatment with aqueous extract of PS and H(2)O(2) for 24 hours. Subsequently, HUVECs were harvested and eNOS mRNA expression was determined using qPCR. The eNOS protein level was measured using ELISA, and the eNOS activity and Nitric oxide level were determined by the Griess reaction. Human umbilical vein endothelial cells treated with aqueous extract of Piper sarmentosum showed a marked induction of Nitric oxide. Treatment with PS also resulted in increased eNOS mRNA expression, eNOS protein level and eNOS activity in HUVECs. Aqueous extract of Piper sarmentosum may improve endothelial function by promoting NO production in HUVECs.

  15. Piper sarmentosum increases nitric oxide production in oxidative stress: a study on human umbilical vein endothelial cells

    Directory of Open Access Journals (Sweden)

    Azizah Ugusman

    2010-01-01

    Full Text Available OBJECTIVE: Nitric oxide produced by endothelial nitric oxide synthase (eNOS possesses multiple anti-atherosclerotic properties. Hence, enhanced expression of eNOS and increased Nitric oxide levels may protect against the development of atherosclerosis. Piper sarmentosum is a tropical plant with antioxidant and anti-inflammatory activities. This study aimed to investigate the effects of Piper sarmentosum on the eNOS and Nitric oxide pathway in cultured human umbilical vein endothelial cells (HUVECs. METHODS: HUVECs were divided into four groups: control, treatment with 180 μM hydrogen peroxide (H2O2, treatment with 150 μg/mL aqueous extract of Piper sarmentosum, and concomitant treatment with aqueous extract of PS and H2O2 for 24 hours. Subsequently, HUVECs were harvested and eNOS mRNA expression was determined using qPCR. The eNOS protein level was measured using ELISA, and the eNOS activity and Nitric oxide level were determined by the Griess reaction. RESULTS: Human umbilical vein endothelial cells treated with aqueous extract of Piper sarmentosum showed a marked induction of Nitric oxide. Treatment with PS also resulted in increased eNOS mRNA expression, eNOS protein level and eNOS activity in HUVECs. CONCLUSION: Aqueous extract of Piper sarmentosum may improve endothelial function by promoting NO production in HUVECs.

  16. Thermogravimetric study of oxidation of a PdCr alloy used for high-temperature sensors

    Science.gov (United States)

    Boyd, Darwin L.; Zeller, Mary V.

    1994-01-01

    In this study, the oxidation of Pd-13 weight percent Cr, a candidate alloy for high-temperature strain gages, was investigated by thermogravimetry. Although the bulk alloy exhibits linear electrical resistivity versus temperature and stable resistivity at elevated temperatures, problems attributed to oxidation occur when this material is fabricated into strain gages. In this work, isothermal thermogravimetry (TG) was used to study the oxidation kinetics. Results indicate that the oxidation of Pd-13 weight percent Cr was approximately parabolic in time at 600 C but exhibited greater passivation from 700 to 900 C. At 1100 C, the oxidation rate again increased.

  17. A comprehensive experimental and modeling study of isobutene oxidation

    KAUST Repository

    Zhou, Chong-Wen

    2016-03-17

    Isobutene is an important intermediate in the pyrolysis and oxidation of higher-order branched alkanes, and it is also a component of commercial gasolines. To better understand its combustion characteristics, a series of ignition delay time (IDT) and laminar flame speed (LFS) measurements have been performed. In addition, flow reactor speciation data recorded for the pyrolysis and oxidation of isobutene is also reported. Predictions of an updated kinetic model described herein are compared with each of these data sets, as well as with existing jet-stirred reactor (JSR) species measurements. IDTs of isobutene oxidation were measured in four different shock tubes and in two rapid compression machines (RCMs) under conditions of relevance to practical combustors. The combination of shock tube and RCM data greatly expands the range of available validation data for isobutene oxidation models to pressures of 50 atm and temperatures in the range 666–1715 K. Isobutene flame speeds were measured experimentally at 1 atm and at unburned gas temperatures of 298–398 K over a wide range of equivalence ratios. For the flame speed results, there was good agreement between different facilities and the current model in the fuel-rich region. Ab initio chemical kinetics calculations were carried out to calculate rate constants for important reactions such as H-atom abstraction by hydroxyl and hydroperoxyl radicals and the decomposition of 2-methylallyl radicals. A comprehensive chemical kinetic mechanism has been developed to describe the combustion of isobutene and is validated by comparison to the presently considered experimental measurements. Important reactions, highlighted via flux and sensitivity analyses, include: (a) hydrogen atom abstraction from isobutene by hydroxyl and hydroperoxyl radicals, and molecular oxygen; (b) radical–radical recombination reactions, including 2-methylallyl radical self-recombination, the recombination of 2-methylallyl radicals with

  18. Oxidative stabilization of polyacrylonitrile nanofibers and carbon nanofibers containing graphene oxide (GO: a spectroscopic and electrochemical study

    Directory of Open Access Journals (Sweden)

    İlknur Gergin

    2017-08-01

    Full Text Available In this study, a precursor for carbon nanofibers (CNF was fabricated via electrospinning and carbonized through a thermal process. Before carbonization, oxidative stabilization should be applied, and the oxidation mechanism also plays an important role during carbonization. Thus, the understanding of the oxidation mechanism is an essential part of the production of CNF. The oxidation process of polyacrylonitrile was studied and nanofiber webs containing graphene oxide (GO are obtained to improve the electrochemical properties of CNF. Structural and morphological characterizations of the webs are carried out by using attenuated total reflectance Fourier transform infrared spectroscopy and Raman spectroscopy, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. Mechanical tests are performed with a dynamic mechanical analyzer, and thermal studies are conducted by using thermogravimetric analysis. Electrochemical impedance spectroscopy, and cyclic voltammetry are used to investigate capacitive behavior of the products. The proposed equivalent circuit model was consistent with charge-transfer processes taking place at interior pores filled with electrolyte.

  19. Oxidation-reduction reactions. Overview and implications for repository studies

    International Nuclear Information System (INIS)

    Apted, Michael J.; Arthur, Randolph C.; Sasamoto, Hiroshi; Yui, Mikazu; Iwatsuki, Teruki

    2001-02-01

    The purpose of this report is to provide a survey and review on oxidation-reduction ('redox') reactions, with particular emphasis on implications for disposal of high-level waste (HLW) in deep geological formations. As an overview, the focus is on basic principles, problems, and proposed research related specifically to the assessment of redox for a HLW repository in Japan. For a more comprehensive treatment of redox and the myriad associated issues, the reader is directed to the cited textbooks used as primary references in this report. Low redox conditions in deep geological formations is a key assumption in the 'Second Progress Report on Research and Development for the Geological Disposal of HLW in Japan' (hereafter called H12'). The release behavior of multi-valent radioelements (e.g., Tc, Se, U, Pu, Np), as well as daughter radioelements of these radioelements, from a deep geological repository are sensitively related to redox conditions. Furthermore, the performance of certain barrier materials, such as overpack and buffer, may be impacted by redox conditions. Given this importance, this report summarizes some key topics for future technical studies supporting site characterization and repository performance as follows: To fully test the conceptual models for system Eh, it will be necessary to measure and evaluate trace element and isotopic information of both coexisting groundwater and reactive minerals of candidate rocks. Because of importance of volatile species (e.g., O 2 , H 2 etc.) in redox reactions, and given the high total pressure of a repository located 500 to 1000 meter deep, laboratory investigations of redox will necessarily require use of pressurized test devices that can fully simulate repository conditions. The stability (redox capacity) of the repository system with respect to potential changes in redox boundary condition induced by oxidizing waters intrusion should be established experimentally. An overall conceptual model that unifies

  20. Trace methane oxidation studied in several Euryarchaeota under diverse conditions

    Directory of Open Access Journals (Sweden)

    James J. Moran

    2005-01-01

    Full Text Available We used 13C-labeled methane to document the extent of trace methane oxidation by Archaeoglobus fulgidus, Archaeoglobus lithotrophicus, Archaeoglobus profundus, Methanobacterium thermoautotrophicum, Methanosarcina barkeri and Methanosarcina acetivorans. The results indicate trace methane oxidation during growth varied among different species and among methanogen cultures grown on different substrates. The extent of trace methane oxidation by Mb. thermoautotrophicum (0.05 ± 0.04%, ± 2 standard deviations of the methane produced during growth was less than that by M. barkeri (0.15 ± 0.04%, grown under similar conditions with H2 and CO2. Methanosarcina acetivorans oxidized more methane during growth on trimethylamine (0.36 ± 0.05% than during growth on methanol (0.07 ± 0.03%. This may indicate that, in M. acetivorans, either a methyltransferase related to growth on trimethylamine plays a role in methane oxidation, or that methanol is an intermediate of methane oxidation. Addition of possible electron acceptors (O2, NO3–, SO22–, SO32– or H2 to the headspace did not substantially enhance or diminish methane oxidation in M. acetivorans cultures. Separate growth experiments with FAD and NAD+ showed that inclusion of these electron carriers also did not enhance methane oxidation. Our results suggest trace methane oxidized during methanogenesis cannot be coupled to the reduction of these electron acceptors in pure cultures, and that the mechanism by which methane is oxidized in methanogens is independent of H2 concentration. In contrast to the methanogens, species of the sulfate-reducing genus Archaeoglobus did not significantly oxidize methane during growth (oxidizing 0.003 ± 0.01% of the methane provided to A. fulgidus, 0.002 ± 0.009% to A. lithotrophicus and 0.003 ± 0.02% to A. profundus. Lack of observable methane oxidation in the three Archaeoglobus species examined may indicate that methyl-coenzyme M reductase, which is not present in

  1. Study of oxide/metal/oxide thin films for transparent electronics and solar cells applications by spectroscopic ellipsometry

    Directory of Open Access Journals (Sweden)

    Mihaela Girtan

    2017-05-01

    Full Text Available A comprehensive study of a class of Oxide/Metal/Oxide (Oxide = ITO, AZO, TiO2 and Bi2O3, Metal = Au thin films was done by correlating the spectrophotometric studies with the ellispometric models. Films were deposited by successive sputtering from metallic targets In:Sn, Zn:Al, Ti and Bi in reactive atmosphere (for the oxide films and respective inert atmosphere (for the metallic Au interlayer films on glass substrates. The measurements of optical constants n—the refractive index and k—the extinction coefficient, at different incident photon energies for single oxide films and also for the three layers films oxide/metal/oxide samples were made using the spectroscopic ellipsometry (SE technique. The ellipsometry modelling process was coupled with the recorded transmission spectra data of a double beam spectrophotometer and the best fitting parameters were obtained not only by fitting the n and k experimental data with the dispersion fitting curves as usual is practiced in the most reported data in literature, but also by comparing the calculated the transmission coefficient from ellipsometry with the experimental values obtained from direct spectrophotometry measurements. In this way the best dispersion model was deduced for each sample. Very good correlations were obtained for the other different thin films characteristics such as the films thickness, optical band gap and electrical resistivity obtained by other measurements and calculation techniques. The ellipsometric modelling, can hence give the possibility in the future to predict, by ellipsometric simulations, the proper device architecture in function of the preferred optical and electrical properties.

  2. Study of water vapour adsorption kinetics on aluminium oxide materials

    Science.gov (United States)

    Livanova, Alesya; Meshcheryakov, Evgeniy; Reshetnikov, Sergey; Kurzina, Irina

    2017-11-01

    Adsorbents on the basis of active aluminum oxide are still of demand on the adsorbent-driers market. Despite comprehensive research of alumina adsorbents, and currently is an urgent task to improve their various characteristics, and especially the task of increasing the sorption capacity. In the present work kinetics of the processes of water vapours' adsorption at room temperature on the surface of desiccant samples has been studied. It was obtained on the basis of bayerite and pseudoboehmite experimentally. The samples of pseudoboehmite modified with sodium and potassium ions were taken as study objects. The influence of an adsorbent's grain size on the kinetics of water vapours' adsorption was studied. The 0.125-0.25 mm and 0.5-1.0 mm fractions of this sample were used. It has been revealed that the saturation water vapor fine powder (0.125-0.25 mm) is almost twofold faster in comparison with the sample of fraction 0.5-1.0 mm due to the decrease in diffusion resistance in the pores of the samples when moving from the sample of larger fraction to the fine-dispersed sample. It has been established that the adsorption capacity of the pseudoboehmite samples, modified by alkaline ions, is higher by ˜40 %, than for the original samples on the basis of bayerite and pseudoboehmite.

  3. Descompresión microvascular en neuralgia del trigémino: Reporte de 36 casos y revisión de la literatura

    Science.gov (United States)

    Campero, Alvaro; Ajler, Pablo; Campero, Abraham Agustín

    2014-01-01

    Objetivo: El propósito del presente trabajo es presentar los resultados de 36 pacientes con diagnóstico de neuralgia del trigémino (NT), en los cuales se realizó una descompresión microvascular (DMV). Material y Método: Desde junio de 2005 a mayo de 2012, 36 pacientes con diagnóstico de NT fueron operados por el primer autor (AC), realizando una DMV. Se evaluó: Edad, sexo, tiempo de sintomatología previo a la cirugía, hallazgos intraoperatorios (a través de los videos quirúrgicos), y resultados postoperatorios. Resultados: De los 36 pacientes operados, 25 fueron mujeres y 11 varones. El promedio de edad fue de 48 años. El seguimiento postoperatorio fue en promedio de 38 meses. De los 36 pacientes, 32 (88%) evolucionaron sin dolor hasta la fecha. De los 4 casos con recurrencia de dolor, en dos pacientes se observó como hallazgo intraoperatorio un conflicto venoso. Conclusión: La DMV como tratamiento de la NT es un procedimiento efectivo y seguro. El hallazgo intraoperatorio de una “compresión” venosa podría indicar una evolución postoperatoria desfavorable. PMID:25379343

  4. 2-22 Study of Oxidation/reduction Volatilization Technology

    Institute of Scientific and Technical Information of China (English)

    Tan; Cunmin[1; Cao; Shiwei[1; Tian; Yuan[1; Qin; Zhi[1

    2015-01-01

    As an advanced dry head-end processing of spent fuel reprocessing, the oxidation-reduction volatilization technology will use for pulverizing uranium oxide ceramic pellets, decladding, and removal of most of volatile and semi-volatile fission elements, 3H, 14C, Kr, Xe, I, Cs, Ru and Tc, from fuel prior to main treatment process. The AIROX and ORIOX process, including circulation of oxidation in oxygen atmosphere and reduction in hydrogen atmosphere, researched on international at present, is considered to be the first choice for head-end processing.

  5. In-Situ Optical Studies of Oxidation/Reduction Kinetics on SOFC Cermet Anodes

    Science.gov (United States)

    2010-12-28

    DATES COVERED (From - To) 1/29/10-9/30/10 4. TITLE AND SUBTITLE In situ optical studies of oxidation/reduction kinetics on SOFC cermet anodes 5a...0572 In-situ Optical Studies of Oxidation/Reduction Kinetics on SOFC Cermet Anodes Department of Chemistry and Biochemistry Montana State University...of Research In-situ Optical Studies of Oxidation/Reduction Kinetics on SOFC Cermet Anodes Principal Investigator Robert Walker Organization

  6. Study of the oxidation kinetics of the nickel-molybdenum alloy

    International Nuclear Information System (INIS)

    Gouillon, Marie-Josephe

    1974-01-01

    This research thesis reports the study of the oxidation of a nickel-molybdenum alloy in the high-nickel-content part of this alloy. After a bibliographical study on the both metals, the author proposes a physical model based on observed phenomena and based on experimental results. Based on a thermodynamic study, the author compares the stability of the different oxides which may be formed, and reports a prediction of oxides obtained on the alloy during oxidation. Qualitative and quantitative studies have been performed by scanning electron microscopy coupled with electronic microprobe analysis to investigate morphological characteristics on oxidation films. A kinetic study by thermogravimetry shows a decrease of the alloy oxidation rate with respect to that of pure nickel at temperatures lower than 800 degrees C. This result is interpreted by the intervention of two opposed diffusion phenomena which act against each other [fr

  7. Studies on Optical and Electrical Properties of Hafnium Oxide Nanoparticles

    Science.gov (United States)

    Jayaraman, Venkatachalam; Sagadevan, Suresh; Sudhakar, Rajesh

    2017-07-01

    In this paper, the synthesis and physico-chemical properties of hafnium oxide nanoparticles (HfO2 NPs) are analyzed and reported. The synthesis was carried out by the precipitation route by using hafnium tetrachloride (HfCl4) as precursor material with potassium hydroxide (KOH) dissolved in Millipore water. In the precipitation technique, the chemical reaction is comparatively simple, low-cost and non-toxic compared to other synthetic methods. The synthesized HfO2 NPs were characterized by using powder x-ray diffraction (PXRD), ultraviolet-visible (UV-Vis) spectroscopy, Raman analysis, and high-resolution transmission electron microscopy (HRTEM). The monoclinic structure of the HfO2 NPs was resolved utilizing x-ray diffraction (XRD). The optical properties were studied from the UV-Vis absorption spectrum. The optical band gap of the HfO2NPs was observed to be 5.1 eV. The Raman spectrum shows the presence of HfO2 NPs. The HRTEM image showed that the HfO2 NPs were of spherical shape with an average particle size of around 28 nm. The energy-dispersive x-ray spectroscopy (EDS) spectrum obviously demonstrated the presence of HfO2 NPs. Analysis and studies on the dielectric properties of the HfO2 NPs such as the dielectric constant, the dielectric loss, and alternating current (AC) conductivity were carried out at varying frequencies and temperatures.

  8. Nuclear quadrupole resonance applied for arsenic oxide study

    International Nuclear Information System (INIS)

    Correia, J.A.S.

    1991-04-01

    The objectives of this study are mounting a pulsed Nuclear Quadrupole Resonance (NQR) building a flow cryostat capable of varying the temperature continuously from 77 K to 340 K and using the spectrometer and the cryostat to study the polycrystalline arsenic oxide. The spin-lattice relaxation time (T 1 ), the spin-spin relaxation time (T 2 ) and the resonance frequency are obtained as a function of temperature. These data are obtained in 77 to 330 K interval. The relaxation times are obtained using the spin echo technique. The spin echo phenomenon is due to refocusing spins, when a 180 0 C pulse is applied after a 90 0 C pulse. The spin-lattice relaxation time is obtained using the plot of echo amplitude versus the repetition time. The spin-spin relaxation time is obtained using the plot of echo amplitude versus the separation between the 90 0 C - 180 0 C pulses. The theory developed by Bayer is used to explain the spin-lattice relaxation time and the frequency temperature dependence. The spin-spin relaxation time is discussed using the Bloch equations. (author)

  9. First-principles study of nitric oxide oxidation on Pt(111) versus Pt overlayer on 3d transition metals

    Energy Technology Data Exchange (ETDEWEB)

    Arevalo, Ryan Lacdao [Department of Precision Science and Technology and Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Escaño, Mary Clare Sison [Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507 (Japan); Kasai, Hideaki, E-mail: kasai@dyn.ap.eng.osaka-u.ac.jp [Department of Precision Science and Technology and Applied Physics, Center for Atomic and Molecular Technologies, and Center for Continuing Professional Development, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2015-03-15

    Catalytic oxidation of NO to NO{sub 2} is a significant research interest for improving the quality of air through exhaust gas purification systems. In this paper, the authors studied this reaction on pure Pt and Pt overlayer on 3d transition metals using kinetic Monte Carlo simulations coupled with density functional theory based first principles calculations. The authors found that on the Pt(111) surface, NO oxidation proceeds via the Eley–Rideal mechanism, with O{sub 2} dissociative adsorption as the rate-determining step. The oxidation path via the Langmuir–Hinshelwood mechanism is very slow and does not significantly contribute to the overall reaction. However, in the Pt overlayer systems, the oxidation of NO on the surface is more thermodynamically and kinetically favorable compared to pure Pt. These findings are attributed to the weaker binding of O and NO on the Pt overlayer systems and the binding configuration of NO{sub 2} that promotes easier N-O bond formation. These results present insights for designing affordable and efficient catalysts for NO oxidation.

  10. Surface morphology study on chromium oxide growth on Cr films by Nd-YAG laser oxidation process

    International Nuclear Information System (INIS)

    Dong Qizhi; Hu Jiandong; Guo Zuoxing; Lian Jianshe; Chen Jiwei; Chen Bo

    2002-01-01

    Grain sized (60-100 nm) Cr 2 O 3 thin films were prepared on Cr thin film surfaces by Nd-YAG laser photothermal oxidation process. Surface morphology study showed crack-free short plateau-like oxide films formed. Increase of dislocation density after pulsed laser irradiation was found. Thin film external surfaces, grain boundaries and dislocations are main paths of laser surface oxidation. Pinning and sealing of grain boundary was the reason that deeper oxidation did not produce. Grain growth and agglomeration of Cr sub-layer yielded tensile stress on the surface Cr 2 O 3 thin film. It was the reason that short plateau-like surface morphology formed and cracks appeared sometimes. In oxygen annealing at 700 deg. C, grain boundaries were considered not to be pinned at the surface, mixture diffusion was main mechanism in growth of oxide. Compression stress development in whole film led to extrusion of grains that was the reason that multiple appearances such as pyramid-like and nutshell-like morphology formed

  11. Mechanism of pyrogallol red oxidation induced by free radicals and reactive oxidant species. A kinetic and spectroelectrochemistry study.

    Science.gov (United States)

    Atala, E; Velásquez, G; Vergara, C; Mardones, C; Reyes, J; Tapia, R A; Quina, F; Mendes, M A; Speisky, H; Lissi, E; Ureta-Zañartu, M S; Aspée, A; López-Alarcón, C

    2013-05-02

    Pyrogallol red (PGR) presents high reactivity toward reactive (radical and nonradical) species (RS). This property of PGR, together with its characteristic spectroscopic absorption in the visible region, has allowed developing methodologies aimed at evaluating the antioxidant capacity of foods, beverages, and human fluids. These methods are based on the evaluation of the consumption of PGR induced by RS and its inhibition by antioxidants. However, at present, there are no reports regarding the degradation mechanism of PGR, limiting the extrapolation to how antioxidants behave in different systems comprising different RS. In the present study, we evaluate the kinetics of PGR consumption promoted by different RS (peroxyl radicals, peroxynitrite, nitrogen dioxide, and hypochlorite) using spectroscopic techniques and detection of product by HPLC mass spectrometry. The same pattern of oxidation and spectroscopic properties of the products is observed, independently of the RS employed. Mass analysis indicates the formation of only one product identified as a quinone derivative, excluding the formation of peroxides or hydroperoxides and/or chlorinated compounds, in agreement with FOX's assays and oxygen consumption experiments. Cyclic voltammetry, carried out at different pH's, shows an irreversible oxidation of PGR, indicating the initial formation of a phenoxy radical and a second charge transfer reaction generating an ortho-quinone derivative. Spectroelectrochemical oxidation of PGR shows oxidation products with identical UV-visible absorption properties to those observed in RS-induced oxidation.

  12. Prenatal development toxicity study of zinc oxide nanoparticles in rats

    Directory of Open Access Journals (Sweden)

    Hong JS

    2014-12-01

    Full Text Available Jeong-Sup Hong,1,2 Myeong-Kyu Park,1 Min-Seok Kim,1 Jeong-Hyeon Lim,1 Gil-Jong Park,1 Eun-Ho Maeng,1 Jae-Ho Shin,3 Meyoung-Kon Kim,4 Jayoung Jeong,5 Jin-A Park,2 Jong-Choon Kim,6 Ho-Chul Shin2 1Health Care Research Laboratory, Korea Testing and Research Institute, Gimpo, South Korea; 2College of Veterinary Medicine, Konkuk University, Seoul, South Korea; 3Department of Biomedical Laboratory Science, Eulji University, Seongnam-si, South Korea; 4Department of Biochemistry and Molecular Biology, Korea University Medical School and College, Seoul, South Korea; 5Toxicological Research Division, National Institute of Food and Drug Safety Evaluation, Chungcheongbuk-do, South Korea; 6College of Veterinary Medicine, Chonnam National University, Gwangju, South Korea Abstract: This study investigated the potential adverse effects of zinc oxide nanoparticles ([ZnOSM20(+ NPs] zinc oxide nanoparticles, positively charged, 20 nm on pregnant dams and embryo–fetal development after maternal exposure over the period of gestational days 5–19 with Sprague-Dawley rats. ZnOSM20(+ NPs were administered to pregnant rats by gavage at 0, 100, 200, and 400 mg/kg/day. All dams were subjected to a cesarean section on gestational day 20, and all of the fetuses were examined for external, visceral, and skeletal alterations. Toxicity in the dams manifested as significantly decreased body weight after administration of 400 mg/kg/day NPs; reduced food consumption after administration of 200 and 400 mg/kg/day NPs; and decreased liver weight and increased adrenal glands weight after administration of 400 mg/kg/day NPs. However, no treatment-related difference in: number of corpora lutea; number of implantation sites; implantation rate (%; resorption; dead fetuses; litter size; fetal deaths and placental weights; and sex ratio were observed between the groups. On the other hand, significant decreases between treatment groups and controls were seen for fetal weights after

  13. Study on IR Properties of Reduced Graphene Oxide

    Science.gov (United States)

    Ma, Deyue; Li, Xiaoxia; Guo, Yuxiang; Zeng, Yurun

    2018-01-01

    Firstly, the reduced graphene oxide was prepared by modified hummer method and characterized. Then, the complex refractive index of reduced graphene oxide in IR band was tested and its IR absorption and radiation properties were researched by correlated calculation. The results show that reduced graphene oxide prepared by hummer method are multilayered graphene with defects and functional groups on its surface. Its absorption in near and far IR bands is strong, but it’s weaker in middle IR band. At the IR atmosphere Window, its normal spectral emissivity decreases with wavelength increasing, and its total normal spectral emissivity in 3 ∼ 5μm and 8 ∼ 14μm are 0.75 and 0.625, respectively. Therefore, reduced graphene oxide can be used as IR absorption and coating materials and have a great potential in microwave and infrared compatible materials.

  14. Zircaloy cladding ID/OD oxidation studies. Final report

    International Nuclear Information System (INIS)

    Westerman, R.E.; Hesson, G.M.

    1977-11-01

    The ID/OD oxide ratio that forms on Zircaloy tubing at temperatures relevant to postulated LOCA conditions was measured as a function of time, temperature, and distance from the rupture. The average ratio at the rupture position was less than unity, and decreased with decreasing test time and increasing distance from the point of rupture. The maximum observed ID/OD oxide ratio was 1.4. Ratios in excess of unity were typically found to be a consequence of the OD oxide being thinner than would have been anticipated from the nominal test conditions. Confirmatory data were also obtained on the isothermal oxidation kinetics of Zircaloy. These data are in good agreement with those obtained by other investigators and confirm the conservative nature of the Baker-Just equation that is required for use in licensing calculations

  15. Kinetic study on electrochemical oxidation of catechols in the ...

    Indian Academy of Sciences (India)

    glassy carbon electrode in different experimental conditions. The electrogenerated ... cancer activities.5 Catechols can be easily oxidized electrochemically to ... from unity and approaches to zero in basic solution. This behavior is related to the ...

  16. Study on the surface oxidation of uranium in different gaseous atmospheres

    International Nuclear Information System (INIS)

    Wang Xiaoling; Fu Yibei; Xie Renshou

    1996-03-01

    The studying for the surface oxidation of uranium and oxide by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS), and the surface oxidation of uranium in different gaseous atmospheres such as O 2 , H 2 , CO, CO 2 , H 2 O(v) and air were reviewed. The surface oxidation of uranium is greatly influenced by a number of parameters including atmospheric temperature, pressure, diffusion of adsorbed gas atoms through the oxide layer, surface and interface chemical component, and defect structure and electron nature of the oxide layer. The initial oxidation mechanism and kinetics have been discussed. Suggestions for future work have also been presented. (32 refs., 7 figs., 5 tabs.)

  17. Study for drifts of the oxidation in nitrous oxide of an activated coal

    International Nuclear Information System (INIS)

    Diaz Velasquez; Jose de Jesus; Carballo Suarez, Luis M; Freitas, Madalena; Farias, Joaquim Luis Faria; Figueiredo, Jose Luis

    2001-01-01

    In order to obtain materials with different surface properties, an activated carbon was modified by thermal treatment with 20% of nitrous oxide in nitrogen at 500 centigrade degrees, for different periods of time, and also with 5 % of oxygen in nitrogen at 425 centigrade degrees for 600 minutes and 100% of hydrogen at 950 centigrade degrees for 360 minutes. Drifts were used to characterize the surface chemistry of the material treated. The qualitative result s show that the treatments with N2O have larger effects on the intensity of the surface groups. These changes could be associated to the incorporation of nitrogen into the carbon matrix. In agreement with literature reports, it could be said that the gas phase oxidation of the activated carbon shows mainly superficial groups such as carboxylic anhydrides, phenols and carboxylates, lactones and quinones

  18. Corrosion study of the graphene oxide and reduced graphene oxide-based epoxy coatings

    Science.gov (United States)

    Ghauri, Faizan Ali; Raza, Mohsin Ali; Saad Baig, Muhammad; Ibrahim, Shoaib

    2017-12-01

    This work aims to determine the effect of graphene oxide (GO) and reduced graphene oxide (rGO) incorporation as filler on the corrosion protection ability of epoxy coatings in saline media. GO was derived from graphite powder following modified Hummers’ method, whereas rGO was obtained after reduction of GO with hydrazine solution. About 1 wt.% of GO or rGO were incorporated in epoxy resin by solution mixing process followed by ball milling. GO and rGO-based epoxy composite coatings were coated on mild steel substrates using film coater. The coated samples were characterized by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests after 1 and 24 h immersion in 3.5% NaCl. The results suggested that GO-based epoxy composite coatings showed high impedance and low corrosion rate.

  19. The study of the oxidation of the natural flavonol fisetin confirmed quercetin oxidation mechanism

    Czech Academy of Sciences Publication Activity Database

    Ramešová, Šárka; Sokolová, Romana; Degano, I.

    2015-01-01

    Roč. 182, NOV 2015 (2015), s. 544-549 ISSN 0013-4686 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR M200401201 Program:M Institutional support: RVO:61388955 Keywords : oxidation * flavonoids * cyclic voltammetry Subject RIV: CG - Electrochemistry Impact factor: 4.803, year: 2015

  20. High-energy photoemission studies of oxide interfaces

    Science.gov (United States)

    Claessen, Ralph

    2015-03-01

    The interfaces of complex oxide heterostructures can host novel quantum phases not existing in the bulk of the constituents, with the high-mobility 2D electron system (2DES) in LaAlO3/SrTiO3 (LAO/STO) representing a prominent example. Despite extensive research the origin of the 2DES and its unusual properties - including the supposed coexistence of superconductivity and ferromagnetism - are still a matter of intense debate. Photoelectron spectroscopy, recently extended into the soft (SX-ARPES) and hard (HAXPES) X-ray regime, is a powerful method to provide detailed insight into the electronic structure of these heterostructures and, in particular, of the buried interface. This includes the identification of the orbital character of the 2DES as well as the determination of vital band structure information, such as band alignment, band bending, and even k-resolved band dispersions and Fermi surface topology. Moreover, resonant photoemission at the Ti L-edge reveals the existence of two different species of Ti 3d states, localized and itinerant, which can be distinguished and identified by their different resonance behavior. The role of oxygen vacancies is studied by controlled in-situ oxidation, which allows us to vary the composition from fully stoichiometric to strongly O-deficient. By comparison to free STO surfaces we can thus demonstrate that the metallicity of the heteointerfaces is intrinsic, i . e . it persists even in the absence of O defects. I will discuss our photoemission results on LAO/STO heterostructures in both (100) and (111) orientation as well as on the related system γ-Al2O3/STO(100), which also hosts a 2DES with an even higher mobility. Work in collaboration with J. Mannhart (MPI-FKF, Stuttgart), N. Pryds (TU Denmark), G. Rijnders (U Twente), S. Suga (U Osaka), M. Giorgoi (BESSY, HZB), W. Drube (DESY Photon Science), V.N. Strocov (Swiss Light Source), J. Denlinger (Advanced Light Source, LBNL), and T.-L. Lee (Diamond Light Source). Support by

  1. Albumin adsorption on oxide thin films studied by spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Silva-Bermudez, P., E-mail: suriel21@yahoo.com [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior s/n, C.U., 04510, Mexico D.F. (Mexico); Unidad de Posgrado, Facultad de Odontologia, Universidad Nacional Autonoma de Mexico, CU, 04510, Mexico D.F. (Mexico); Rodil, S.E.; Muhl, S. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior s/n, C.U., 04510, Mexico D.F. (Mexico)

    2011-12-15

    Thin films of tantalum, niobium, zirconium and titanium oxides were deposited by reactive magnetron sputtering and their wettability and surface energy, optical properties, roughness, chemical composition and microstructure were characterized using contact angle measurements, spectroscopic ellipsometry, profilometry, X-ray photoelectron spectroscopy and X-ray diffraction, respectively. The purpose of the work was to correlate the surface properties of the films to the Bovine Serum Albumin (BSA) adsorption, as a first step into the development of an initial in vitro test of the films biocompatibility, based on standardized protein adsorption essays. The films were immersed into BSA solutions with different protein concentrations and protein adsorption was monitored in situ by dynamic ellipsometry; the adsorption-rate was dependent on the solution concentration and the immersion time. The overall BSA adsorption was studied in situ using spectroscopic ellipsometry and it was found to be influenced by the wettability of the films; larger BSA adsorption occurred on the more hydrophobic surface, the ZrO{sub 2} film. On the Ta{sub 2}O{sub 5}, Nb{sub 2}O{sub 5} and TiO{sub 2} films, hydrophilic surfaces, the overall BSA adsorption increased with the surface roughness or the polar component of the surface energy.

  2. Nitrosation of melatonin by nitric oxide: a computational study.

    Science.gov (United States)

    Turjanski, A G; Sáenz, D A; Doctorovich, F; Estrin, D A; Rosenstein, R E

    2001-09-01

    Melatonin is being increasingly promoted as a therapeutic agent for the treatment of jet lag and insomnia, and is an efficient free radical scavenger. We have recently characterized a product for the reaction of melatonin with nitric oxide (NO), N-nitrosomelatonin. In the present work, reaction pathways with N1, C2, C4, C6 and C7 as possible targets for its reaction with NO that yield the respective nitroso derivatives have been investigated using semiempirical AM1 computational tools, both in vacuo and aqueous solution. Specifically, two different pathways were studied: a radical mechanism involving the hydrogen atom abstraction to yield a neutral radical followed by NO addition, and an ionic mechanism involving addition of nitrosonium ion to the indolic moiety. Our results show that the indolic nitrogen is the most probable site for nitrosation by the radical mechanism, whereas different targets are probable considering the ionic pathway. These results are in good agreement with previous experimental findings and provide a coherent picture for the interaction of melatonin with NO.

  3. The kinetic study of oxidation of iodine by hydrogen peroxide

    International Nuclear Information System (INIS)

    Cantrel, L.; Chopin, J.

    1996-01-01

    Iodine chemistry is one of the most important subjects of research in the field of reactor safety because this element can form volatile species which represent a biological hazard for environment. As the iodine and the peroxide are both present in the sump of the containment in the event of a severe accident on a light water nuclear reactor, it can be important to improve the knowledge on the reaction of oxidation of iodine by hydrogen peroxide. The kinetics of iodine by hydrogen peroxide has been studied in acid solution using two different analytical methods. The first is a UV/Vis spectrophotometer which records the transmitted intensity at 460 nm as a function of time to follow the decrease of iodine concentration, the second is an amperometric method which permits to record the increase of iodine+1 with time thanks to the current of reduction of iodine+1 to molecular iodine. The iodine was generated by Dushman reaction and the series of investigations were made at 40 o C in a continuous stirring tank reactor. The influence of the initial concentrations of iodine, iodate, hydrogen peroxide, H + ions has been determined. The kinetics curves comprise two distinct chemical phases both for molecular iodine and for iodine+1. The relative importance of the two processes is connected to the initial concentrations of [I 2 ], [IO 3 - ], [H 2 O 2 ] and [H + ]. A rate law has been determined for the two steps for molecular iodine. (author) figs., tabs., 22 refs

  4. Positronium formation studies in crystalline molecular complexes: Triphenylphosphine oxide - Acetanilide

    Science.gov (United States)

    Oliveira, F. C.; Denadai, A. M. L.; Guerra, L. D. L.; Fulgêncio, F. H.; Windmöller, D.; Santos, G. C.; Fernandes, N. G.; Yoshida, M. I.; Donnici, C. L.; Magalhães, W. F.; Machado, J. C.

    2013-04-01

    Hydrogen bond formation in the triphenylphosphine oxide (TPPO), acetanilide (ACN) supramolecular heterosynton system, named [TPPO0.5·ACN0.5], has been studied by Positron Annihilation Lifetime Spectroscopy (PALS) and supported by several analytical techniques. In toluene solution, Isothermal Titration Calorimetry (ITC) presented a 1:1 stoichiometry and indicated that the complexation process is driven by entropy, with low enthalpy contribution. X-ray structure determination showed the existence of a three-dimensional network of hydrogen bonds, allowing also the confirmation of the existence of a 1:1 crystalline molecular complex in solid state. The results of thermal analysis (TGA, DTA and DSC) and FTIR spectroscopy showed that the interactions in the complex are relatively weaker than those found in pure precursors, leading to a higher positronium formation probability at [TPPO0.5·ACN0.5]. These weak interactions in the complex enhance the possibility of the n- and π-electrons to interact with positrons and consequently, the probability of positronium formation is higher. Through the present work is shown that PALS is a sensible powerful tool to investigate intermolecular interactions in solid heterosynton supramolecular systems.

  5. Positron annihilation lifetime study of oxide dispersion strengthened steels

    International Nuclear Information System (INIS)

    Krsjak, V.; Szaraz, Z.; Hähner, P.

    2012-01-01

    A comparative positron annihilation lifetime study has been performed on various commercial ferritic and ferritic/martensitic oxide dispersion strengthened (ODS) steels. Both as-extruded and recrystallized materials were investigated. In the materials with recrystallized coarse-grained microstructures, only the positron trapping at small vacancy clusters and yttria nanofeatures was observed. Materials which had not undergone recrystallization treatment clearly showed additional positron trapping which is associated with dislocations. Dislocation densities were calculated from a two-component decomposition of the positron lifetime spectra by assuming the first component to be a superposition of the bulk controlled annihilation rate and the dislocation controlled trapping rate. The second component (which translates into lifetimes of 240–260 ps) was found to be well separated in all those ODS materials. This paper presents the potentialities and limitations of the positron annihilation lifetime spectroscopy, and discusses the results of the experimental determination of the defect concentrations and sensitivity of this technique to the material degradation due to thermally induced precipitation of chromium-rich α′ phases.

  6. Study of the oxidation of Fe-Cr alloys at high temperatures

    International Nuclear Information System (INIS)

    Carneiro, J.F.; Sabioni, A.C.S.

    2010-01-01

    The high temperature oxidation behavior of Fe-1.5%Cr, Fe-5.0%Cr, Fe-10%Cr and Fe- 15%Cr model alloys were investigated from 700 to 850 deg C, in air atmosphere. The oxidation treatments were performed in a thermobalance with a sensitivity of 1μg. The oxide films grown by oxidation of the alloys were characterized by scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The oxide films are Fe-Cr spinels with variable composition depending on the alloy composition. For all conditions studied, the oxidation kinetics of these alloys follow a parabolic law. The comparison of the oxidation rates of the four alloys, at 700 deg C, shows that the parabolic oxidation constants decrease from 1.96x10 -9 g 2 .cm -4 .s -1 , for the alloy Fe-1.5% Cr, to 1.18 x 10-14g 2 .cm -4 .s -1 for the alloy Fe-15% Cr. Comparative analysis of the oxidation behavior of the Fe-10%Cr and Fe-15%Cr alloys, between 700 and 850 deg C, shows that the oxidation rates of these alloys are comparable to 800 deg C, above this temperature the Fe-10%Cr alloy shows lower resistance to oxidation. (author)

  7. Controlled nitric oxide production via O(1D) + N2O reactions for use in oxidation flow reactor studies

    Science.gov (United States)

    Lambe, Andrew; Massoli, Paola; Zhang, Xuan; Canagaratna, Manjula; Nowak, John; Daube, Conner; Yan, Chao; Nie, Wei; Onasch, Timothy; Jayne, John; Kolb, Charles; Davidovits, Paul; Worsnop, Douglas; Brune, William

    2017-06-01

    Oxidation flow reactors that use low-pressure mercury lamps to produce hydroxyl (OH) radicals are an emerging technique for studying the oxidative aging of organic aerosols. Here, ozone (O3) is photolyzed at 254 nm to produce O(1D) radicals, which react with water vapor to produce OH. However, the need to use parts-per-million levels of O3 hinders the ability of oxidation flow reactors to simulate NOx-dependent secondary organic aerosol (SOA) formation pathways. Simple addition of nitric oxide (NO) results in fast conversion of NOx (NO + NO2) to nitric acid (HNO3), making it impossible to sustain NOx at levels that are sufficient to compete with hydroperoxy (HO2) radicals as a sink for organic peroxy (RO2) radicals. We developed a new method that is well suited to the characterization of NOx-dependent SOA formation pathways in oxidation flow reactors. NO and NO2 are produced via the reaction O(1D) + N2O → 2NO, followed by the reaction NO + O3 → NO2 + O2. Laboratory measurements coupled with photochemical model simulations suggest that O(1D) + N2O reactions can be used to systematically vary the relative branching ratio of RO2 + NO reactions relative to RO2 + HO2 and/or RO2 + RO2 reactions over a range of conditions relevant to atmospheric SOA formation. We demonstrate proof of concept using high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) measurements with nitrate (NO3-) reagent ion to detect gas-phase oxidation products of isoprene and α-pinene previously observed in NOx-influenced environments and in laboratory chamber experiments.

  8. Development studies for a novel wet oxidation process

    International Nuclear Information System (INIS)

    Dhooge, P.M.; Hakim, L.B.

    1994-01-01

    A catalytic wet oxidation process (DETOX), which uses an acidic iron solution to oxidize organic compounds to carbon dioxide, water, and other simple products, was investigated as a potential method for the treatment of multicomponent hazardous and mixed wastes. The organic compounds picric acid, poly(vinyl chloride), tetrachlorothiophene, pentachloropyridine, Aroclor 1260 (a polychlorinated biphenyl), and hexachlorobenzene were oxidized in 125 ml reaction vessels. The metals arsenic, barium, beryllium, cadmium, cerium (as a surrogate for plutonium), chromium, lead, mercury, neodymium (as a surrogate for uranium), nickel, and vanadium were tested in the DETOX solution. Barium, beryllium, cerium, chromium, mercury, neodymium, nickel, and vanadium were all found to be very soluble (>100 g/l) in the DETOX chloride-based solution. Arsenic, barium, cadmium, and lead solubilities were lower. Lead could be selectively precipitated from the DETOX solution. Chromium(VI) was reduced to relatively non-toxic chromium(III) by the solution. Six soils were contaminated with arsenic, barium, beryllium, chromium, lead, and neodymium oxides at approximately 0.1% by weight, and benzene, trichloroethene, mineral oil, and Aroclor 1260 at approximately 5% by weight total, and 5.g amounts treated with the DETOX solution in unstirred 125. ml reaction bombs. It is felt that soil treatment in a properly designed system is entirely possible despite incomplete oxidation of the less volatile organic materials in these unstirred tests

  9. Moessbauer Study of Electrodeposited Fe/Fe-Oxide Multilayers

    International Nuclear Information System (INIS)

    Kuzmann, E.; Homonnay, Z.; Klencsar, Z.; Vertes, A.; Lakatos-Varsanyi, M.; Miko, A.; Varga, L.K.; Kalman, E.; Nagy, F.

    2005-01-01

    Iron has been deposited electrochemically by short current pulses in Na-saccharin containing FeII-chloride and sulphate solution electrolytes. Combined electrochemical techniques with initial pulse plating of iron nanolayer and its subsequent anodic oxidation under potential control have been used for production of Fe/Fe-oxide multilayers. 57Fe CEM spectra of pulse plated iron revealed the presence of a minor doublet attributed mainly to γ-FeOOH in addition to the dominant sextet of α-iron. In the case of anodically oxidized pulse plated iron and of samples after repeated deposition of anodically oxidized pulse plated iron an additional minor doublet, assigned to ferrous chloride, also appears in the Moessbauer spectra. A significant change in the magnetic anisotropy of α-iron was observed with the anodic oxidation. The thickness of the layers were estimated from the CEM spectrum data by a modified computer program of the Liljequist method. The coercive field and the power loss versus frequency data showed that the pulse plated iron cores are good inductive elements up to several kHz frequencies

  10. Thermogravimetric study of reduction of oxides present in oxidized nickel-base alloy powders

    Science.gov (United States)

    Herbell, T. P.

    1976-01-01

    Carbon, hydrogen, and hydrogen plus carbon reduction of three oxidized nickel-base alloy powders (a solid solution strengthened alloy both with and without the gamma prime formers aluminum and titanium and the solid solution strengthened alloy NiCrAlY) were evaluated by thermogravimetry. Hydrogen and hydrogen plus carbon were completely effective in reducing an alloy containing chromium, columbium, tantalum, molybdenum, and tungsten. However, with aluminum and titanium present the reduction was limited to a weight loss of about 81 percent. Carbon alone was not effective in reducing any of the alloys, and none of the reducing conditions were effective for use with NiCrAlY.

  11. Kinetics studies of oxidation of niacinamide by alkaline potassium permanganate

    Directory of Open Access Journals (Sweden)

    Sandipsingh Gour

    2012-04-01

    Full Text Available The oxidation of niacinamide in alkaline media is carried out using potassium permanganate as a oxiding agent. The reaction was monitored using UV-Visible spectrophotometer at 525 nm. It was found to be zero order with respect to oxidant,, fractional order with respect to hydrogen ion concentration and first order with respect to substrate. The thermodynamic parameters(were determinied . The average (?G# was found to be 87.60 KJ/mol. The values ?S# was found to be -0.2132 KJ/mole and energy of activation was found to be 23.95 KJ/mole. A suitable mechanism is proposed based on the experimental conditions.

  12. Development studies of a novel wet oxidation process

    International Nuclear Information System (INIS)

    Rogers, T.W.; Dhooge, P.M.

    1995-01-01

    Many DOE waste streams and remediates contain complex and variable mixtures of organic compounds, toxic metals, and radionuclides. These materials are often dispersed in organic or inorganic matrices, such as personal protective equipment, various sludges, soils, and water. Incineration and similar combustive processes do not appear to be viable options for treatment of these waste streams due to various considerations. The objective of this project is to develop a novel catalytic wet oxidation process for the treatment of multi-component wastes. The DETOX process uses a unique combination of metal catalysts to increase the rate of oxidation of organic materials

  13. High pressure structural studies on nanophase praseodymium oxide

    International Nuclear Information System (INIS)

    Saranya, L.; Chandra Shekar, N.V.; Amirthapandian, S.; Hussain, Shamima; Arulraj, A.; Sahu, P. Ch.

    2014-01-01

    The phase stability of nanocrystalline Pr 2 O 3 has been investigated under pressure by in-situ high pressure X-ray diffraction using Mao-Bell type diamond anvil cell. The ambient structure and phase of the praseodymium oxide have been resolved unambiguously using x-ray diffraction, SEM and TEM techniques. Under the action of pressure the cubic phase of the system is retained up to 15 GPa. This is unusual as other isostructural rare earth oxides show structural transformations even at lower pressures. From the best fit to the P–V data with the Murnaghan equation of state yields a bulk modulus of 171 GPa

  14. Development studies of a novel wet oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, T.W.; Dhooge, P.M. [Delphi Research, Inc., Albuquerque, NM (United States)

    1995-10-01

    Many DOE waste streams and remediates contain complex and variable mixtures of organic compounds, toxic metals, and radionuclides. These materials are often dispersed in organic or inorganic matrices, such as personal protective equipment, various sludges, soils, and water. Incineration and similar combustive processes do not appear to be viable options for treatment of these waste streams due to various considerations. The objective of this project is to develop a novel catalytic wet oxidation process for the treatment of multi-component wastes. The DETOX process uses a unique combination of metal catalysts to increase the rate of oxidation of organic materials.

  15. The kinetic study of oxidation of iodine by hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Cantrel, L [Institut de Protection et de Surete Nucleaire, IPNS, CEN Cadarache, Saint Paul lez Durance (France); Chopin, J [Laboratoire d` Electrochimie Inorganique, ENSSPICAM, Marseille (France)

    1996-12-01

    Iodine chemistry is one of the most important subjects of research in the field of reactor safety because this element can form volatile species which represent a biological hazard for environment. As the iodine and the peroxide are both present in the sump of the containment in the event of a severe accident on a light water nuclear reactor, it can be important to improve the knowledge on the reaction of oxidation of iodine by hydrogen peroxide. The kinetics of iodine by hydrogen peroxide has been studied in acid solution using two different analytical methods. The first is a UV/Vis spectrophotometer which records the transmitted intensity at 460 nm as a function of time to follow the decrease of iodine concentration, the second is an amperometric method which permits to record the increase of iodine+1 with time thanks to the current of reduction of iodine+1 to molecular iodine. The iodine was generated by Dushman reaction and the series of investigations were made at 40{sup o}C in a continuous stirring tank reactor. The influence of the initial concentrations of iodine, iodate, hydrogen peroxide, H{sup +} ions has been determined. The kinetics curves comprise two distinct chemical phases both for molecular iodine and for iodine+1. The relative importance of the two processes is connected to the initial concentrations of [I{sub 2}], [IO{sub 3}{sup -}], [H{sub 2}O{sub 2}] and [H{sup +}]. A rate law has been determined for the two steps for molecular iodine. (author) figs., tabs., 22 refs.

  16. Studies on mixed metal oxides solid solutions as heterogeneous catalysts

    Directory of Open Access Journals (Sweden)

    H. R. Arandiyan

    2009-03-01

    Full Text Available In this work, a series of perovskite-type mixed oxide LaMo xV1-xO3+δ powder catalysts (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0, with 0.5 < δ < 1.5, prepared by the sol-gel process and calcined at 750ºC, provide an attractive and effective alternative means of synthesizing materials with better control of morphology. Structures of resins obtained during the gel formation process by FT-IR spectroscopy and XRD analysis showed that all the LaMo xV1-xO3+δ samples are single phase perovskite-type solid solutions. The surface area (BET between 2.5 - 5.0 m²/g (x = 0.1 and 1.0 respectively increases with increasing Mo ratio in the samples. They show high purity, good chemical homogeneity, and lower calcinations temperatures as compared with the solid-state chemistry route. SEM coupled to EDS and thermogravimetric analysis/differential thermal analyses (TGA/DTA have been carried out in order to evaluate the homogeneity of the catalyst. Finally, the experimental studies show that the calcination temperature and Mo content exhibited a significant influence on catalytic activity. Among the LaMo xV1-xO3+δ samples, LaMo0.7V0.3O4.2 showed the best catalytic activity for the topic reaction and the best activity and stability for ethane reforming at 850ºC under 8 bar.

  17. Thermogravimetric study of the reaction of uranium oxides with fluorine

    International Nuclear Information System (INIS)

    Komura, Motohiro; Sato, Nobuaki; Kirishima, Akira; Tochiyama, Osamu

    2008-01-01

    Thermogravimetric study of the reaction of uranium oxides with fluorine was conducted by TG-DTA method using anti-corrosion type differential thermobalance. When UO 2 was heated from R.T. to 500 deg. C in 5% F 2 /He atmosphere, the weight increase appeared at ca. 250 deg. C with an exothermic peak. Then the weight decreased slightly with a small exothermic peak followed by the complete volatilization with a large exothermic peak at ca. 350 deg. C. At a flow rate of 15, 30, 60 ml min -1 , there seemed to be no significant change for the fluorination of UO 2 . With the different heating rates of 1, 2, 5 and 10 deg. C min -1 , the fluorination peak shifted to higher temperature with increasing heating rates. For the comparison with thermogravimetric results, phase analysis by XRD method was conducted for the products obtained at different temperatures. At 260 deg. C, the product was UO 2 with a small amount of the intermediate compound, UO 2 F. The amount of this compound increased with increasing temperature up to 320 deg. C. Then another phase of UO 2 F 2 appeared at 340 deg. C but it was immediately fluorinated to the volatile fluoride. When U 3 O 8 was used as a starting material, it was found that the steep weight decrease peak appeared at ca. 350 deg. C and the uranium volatilized completely. This result suggests that fluorination of U 3 O 8 occurs at this temperature forming UF 6 . Uranium trioxide showed the similar fluorination behavior to that of U 3 O 8

  18. Study of thin metal films and oxide materials for nanoelectronics applications

    OpenAIRE

    De Los Santos Valladares, Luis

    2012-01-01

    Appendix A Pages 132-134 have been removed from this online version of the thesis for publisher copyright reasons. These had contained page images from the cover of Nanotechnology, Vol. 21, Nov 2010 and its corresponding web alert Different types of thin metal films and oxide materials are studied for their potential application in nanoelectronics: gold and copper films, nickel nanoelectrodes, oxide nanograin superconductors, carboxyl ferromagnetic microspheres and graphene oxide...

  19. In Situ Raman Spectroscopy of Supported Chromium Oxide Catalysts: Reactivity Studies with Methanol and Butane

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Wachs, I.E.

    1996-01-01

    The interactions of methanol and butane with supported chromium oxide catalysts under oxidizing and reducing conditions were studied by in situ Raman spectroscopy as a function of the specific oxide support (Al2O3, ZrO2, TiO2, SiO2, Nb2O5, 3% SiO2/TiO2, 3% TiO2/SiO2, and a physical mixture of SiO2

  20. Growth of micrometric oxide layers for the study of metallic surfaces decontamination by laser

    OpenAIRE

    Carvalho Luisa; Pacquentin Wilfried; Tabarant Michel; Maskrot Hicham; Semerok Alexandre

    2017-01-01

    The nuclear industry produces a wide range of radioactive waste in term of level of hazard, contaminants and material. For metallic equipment like steam generators, the radioactivity is mainly located in the oxide surface. In order to study and develop techniques for dismantling and for decontamination in a safe way, it is important to have access to oxide layers with a representative distribution of non-radioactive contaminants. We propose a method of formation of oxide layer on stainless st...

  1. Salt-stone Oxidation Study: Leaching Method - 13092

    International Nuclear Information System (INIS)

    Langton, C.A.; Stefanko, D.B.; Burns, H.H.

    2013-01-01

    Cementitious waste forms can be designed to chemically stabilize selected contaminants, such as Tc +7 and Cr +6 , by chemically reduction to lower valance states, Tc +4 and Cr +3 , respectively, and precipitation of these species in alkaline media as low solubility solid phases. Data for oxidation of this type of cementitious waste form cured under field conditions as a function of time is required for predicting the performance of the waste form and disposal facility. The rate of oxidation (oxidation front advancement) is an important parameter for predicting performance because the solubilities of some radionuclide contaminants, e.g., technetium, are a function of the oxidation state. A non-radioactive experiment was designed for quantifying the oxidation front advancement using chromium, as an approximate redox-sensitive surrogate (Cr +6 / Cr +3 ) for technetium (Tc +7 / Tc +4 ). Nonradioactive cementitious waste forms were prepared in the laboratory and cured under both laboratory and 'field conditions'. Laboratory conditions were ambient temperature and sealed sample containers. Field conditions were approximated by curing samples in open containers which were placed inside a plastic container stored outdoors at SRS. The container had a lid and was instrumented with temperature and humidity probes. Sub-samples as thin as 0.2 mm were taken as a function of distance from the exposed surface of the as-cast sample. The sub-samples were leached and the leachates were analyzed for chromium, nitrate, nitrite and sodium. Nitrate, nitrite, and sodium concentrations were used to provide baseline data because these species are not chemically retained in the waste form matrix to any significant extent and are not redox sensitive. 'Effective' oxidation fronts for Cr were measured for samples containing 1000, 500 and 20 mg/kg Cr added as soluble sodium chromate, Na 2 CrO 4 . For a sample cured for 129 days under field conditions, leachable Cr (assumed to be the oxidized

  2. Salt-stone Oxidation Study: Leaching Method - 13092

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.A.; Stefanko, D.B.; Burns, H.H. [Savannah River National Laboratory, Savannah River Remediation, LLC, Savannah River Site, Aiken, SC 29808 (United States)

    2013-07-01

    Cementitious waste forms can be designed to chemically stabilize selected contaminants, such as Tc{sup +7} and Cr{sup +6}, by chemically reduction to lower valance states, Tc{sup +4} and Cr{sup +3}, respectively, and precipitation of these species in alkaline media as low solubility solid phases. Data for oxidation of this type of cementitious waste form cured under field conditions as a function of time is required for predicting the performance of the waste form and disposal facility. The rate of oxidation (oxidation front advancement) is an important parameter for predicting performance because the solubilities of some radionuclide contaminants, e.g., technetium, are a function of the oxidation state. A non-radioactive experiment was designed for quantifying the oxidation front advancement using chromium, as an approximate redox-sensitive surrogate (Cr{sup +6} / Cr{sup +3}) for technetium (Tc{sup +7} / Tc{sup +4}). Nonradioactive cementitious waste forms were prepared in the laboratory and cured under both laboratory and 'field conditions'. Laboratory conditions were ambient temperature and sealed sample containers. Field conditions were approximated by curing samples in open containers which were placed inside a plastic container stored outdoors at SRS. The container had a lid and was instrumented with temperature and humidity probes. Sub-samples as thin as 0.2 mm were taken as a function of distance from the exposed surface of the as-cast sample. The sub-samples were leached and the leachates were analyzed for chromium, nitrate, nitrite and sodium. Nitrate, nitrite, and sodium concentrations were used to provide baseline data because these species are not chemically retained in the waste form matrix to any significant extent and are not redox sensitive. 'Effective' oxidation fronts for Cr were measured for samples containing 1000, 500 and 20 mg/kg Cr added as soluble sodium chromate, Na{sub 2}CrO{sub 4}. For a sample cured for 129 days

  3. Interlab study on nanotoxicology of representative graphene oxide

    Science.gov (United States)

    Durán, Nelson; Martinez, Diego S. T.; Justo, Giselle Z.; de Lima, Renata; Lúcia de Castro, Vera; Umbuzeiro, Gisela A.; Barbieri, Edison; Durán, Marcela; Melo, Patricia S.; Alves, Oswaldo L.; Fávaro, Wagner J.

    2015-05-01

    The graphene sample GO:Single-layer graphene oxide, purity 99%, thickness 0.7-1.2 nm (AFM); ∼300-800nm X&Y dimensions is the standard size embryonic fibroblast cells (3T3), human keratinocytes (HaCaT), colorectal cancer cells (Caco-2/HCT 116), Lewis lung cancer cells (3LL), acute myeloid leukemia cells (KG-1, Jurkat, Kasumi-1) and chronic myeloid leukemia cells (K562, Lucena) and no significant toxicity was found after exposition to 0.1-100 μg/mL for 24 and 48 h. Breast cancer cells, MCF-7, showed a 20% reduction on cell viability at 24 and 48 h. No cytotoxicity were found in lymphocytes, Chinese hamster ovary cells (CHO) and human macrophage cell line (U937) at 0.1-50 μg/mL, but 30-50% survival inhibition was observed at 100 μg/mL. A dose-dependent increase in apoptosis was observed in some cells (Kasumi-1, Jurkatand K562 cells). In the case of CHO and 3T3 cells, greater levels of necrosis with increasing concentrations of GO (>50 μg/mL) were observed. Genotoxic study using the Comet assay showed slight DNA damage in lymphocytes at all concentrations tested, while more significant effects was observed in CHO cells. Econanotoxicity was carried out by lethality assays in the nematode Caenorhabditis elegans, d in the freshwater coelenterate Hydra, Daphania amd in Shrimp with no signs of toxicity at concentrations varying from 0.1-100 μg/mL of GO. However, death and disintegration of Hydra was observed after exposition to 100 μg/mL for 72 h. In in vivo studies, no changes in biochemical parameters of Fischer 344 rats were observed after the i.p. administration of GO. Some black agglomerates were found in the intraperitoneal cavity of rats injected with GO. However, in Fisher 344 rats-bearing prostate tumors, treatment with GO (up to 100 μg/mL) negatively affected the hepatic parameters, whilst in the renal ones, an improvement was observed. Studies are in progress to understand the mechanisms involved in the uptake of GO by RES. GO appears as a potential non

  4. THE FTIR STUDIES OF PHOTO-OXIDATIVE DEGRADATION OF POLYPROPYLENE

    Institute of Scientific and Technical Information of China (English)

    WEN Zaiqing; HU Xingzhou; SHEN Deyan

    1988-01-01

    The photo-oxidative degradation process of polypropylene film containing iron ions was investigated via FTIR and absorbance substraction technique. It is shown that the iron ions play an important role in the decomposition of hydroperoxide and the increase of the degradation rate of polypropylene film. Theamorphous region of PP film undergoes degradation prior to the crystalline one.

  5. A study of nanosized zinc oxide and its nanofluid

    Indian Academy of Sciences (India)

    Metal oxide nanostructures can be used in solar cells, ... acterization of ZnO nanoparticles, ZnO–ethylene glycol and ZnO–water nanofluids are reported .... be attributed to the fact that potassium hydroxide was used in the reaction process. The.

  6. Ab initio and kinetic modeling studies of formic acid oxidation

    DEFF Research Database (Denmark)

    Marshall, Paul; Glarborg, Peter

    2015-01-01

    A detailed chemical kinetic model for oxidation of formic acid (HOCHO) in flames has been developed, based on theoretical work and data from literature. Ab initio calculations were used to obtain rate coefficients for reactions of HOCHO with H, O, and HO2. Modeling predictions with the mechanism...

  7. The study and microstructure analysis of zinc and zinc oxide

    Czech Academy of Sciences Publication Activity Database

    Luptáková, Natália; Pešlová, F.; Kliber, J.

    2015-01-01

    Roč. 54, č. 1 (2015), s. 43-46 ISSN 0543-5846 Grant - others:KEGA(SK) KEGA 007 TnUAD-4/2013 Institutional support: RVO:68081723 Keywords : zinc * production of zinc oxide * microstructure * chemical composition * zinc slag Subject RIV: JG - Metal lurgy Impact factor: 0.959, year: 2014

  8. Study of nano-structured ceria for catalytic CO oxidation

    Czech Academy of Sciences Publication Activity Database

    Valechha, D.; Lokhande, S.; Klementová, Mariana; Šubrt, Jan; Rayalu, S.; Labhsetwar, N.

    2011-01-01

    Roč. 21, č. 11 (2011), s. 3718-3725 ISSN 0959-9428 Institutional research plan: CEZ:AV0Z40320502 Keywords : mesoporous CeO2 * titania * alumina * oxides Subject RIV: CA - Inorganic Chemistry Impact factor: 5.968, year: 2011

  9. In Situ Study of Noncatalytic Metal Oxide Nanowire Growth

    DEFF Research Database (Denmark)

    Rackauskas, Simas; Jiang, Hua; Wagner, Jakob Birkedal

    2014-01-01

    a catalyst is still widely disputed and unclear. Here, we show that the nanowire growth during metal oxidation is limited by a nucleation of a new layer. On the basis of in situ transmission electron microscope investigations we found that the growth occurs layer by layer at the lowest specific surface...

  10. Fluorescence studies of Rhodamine 6G functionalized silicon oxide nanostructures

    International Nuclear Information System (INIS)

    Baumgaertel, Thomas; Borczyskowski, Christian von; Graaf, Harald

    2010-01-01

    Selective anchoring of optically active molecules on nanostructured surfaces is a promising step towards the creation of nanoscale devices with new functionalities. Recently we have demonstrated the electrostatic attachment of charged fluorescent molecules on silicon oxide nanostructures prepared by atomic force microscopy (AFM) nanolithography via local anodic oxidation (LAO) of dodecyl-terminated silicon. In this paper we report on our findings from a more detailed optical investigation of the bound dye Rhodamine 6G. High sensitivity optical wide field microscopy as well as confocal laser microscopy have been used to characterize the Rhodamine fluorescence emission. A highly interesting question concerns the interaction between an emitter close to a silicon surface because mechanisms such as energy transfer and fluorescence quenching will occur which are still not fully understood. Since the oxide thickness can be varied during preparation continuously from 1 to ∼ 5 nm, it is possible to investigate the fluorescence of the bound dye in close proximity to the underlying silicon. Using confocal laser microscopy we were also able to obtain optical spectra from the bound molecules. Together with the results from an analysis of their photochemical bleaching behaviour, we conjecture that some of the Rhodamine 6G molecules on the structure are interacting with the oxide, causing a spectral shift and differences in their photochemical properties.

  11. Study of ionic movements during anodic oxidation of nitrogen-implanted aluminium

    International Nuclear Information System (INIS)

    Terwagne, G.; Lucas, S.; Bodart, F.; Sorensen, G.; Jensen, H.

    1990-01-01

    In recent years there has been a considerable interest in synthesizing aluminium nitrides by ion implantation in order to modify the tribological properties of aluminium. The growth of an oxide layer by anodic process on these synthesized aluminium nitrides gives an interesting oxide-on-semiconductor material with surprising dynamic and decorative properties. During the anodic oxidation, ionic movements are involved in the near-surface region of the aluminium material; these ionic movements have been studied by Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) on thin aluminium foils (7000 A) preimplanted with nitrogen and post-oxidized in an ammonium pentaborate solution. The growth of the oxide layer is reduced when the aluminium is preimplanted with nitrogen: the speed of oxidation depends on the implantation conditions (energy and fluence). Moreover, the aluminium nitride can be dissolved when all metallic aluminium staying between the surface and the AlN are consumed by the anodic process. (orig.)

  12. Combining Raman Microprobe and XPS to Study High Temperature Oxidation of Metals

    International Nuclear Information System (INIS)

    Windisch, Charles F.; Henager, Charles H.; Engelhard, Mark H.; Bennett, Wendy D.

    2011-01-01

    Raman microprobe spectroscopy was applied in studies of high-temperature air oxidation of a ferritic alloy (HT-9) in the absence and presence of zirconia coatings with the objective of evaluating the technique as a way to quickly screen candidate cladding materials and actinide-based mixed oxide fuel mixtures for advanced nuclear reactors. When oxidation was relatively uniform, Raman spectra collected using microscope optics with low spatial resolution were found to be similar to those collected with conventional Raman spectroscopy. These spectra could be used to identify major oxide corrosion products and follow changes in the composition of the oxides due to heating. However, when the oxidation films were comprised of multiple layers of varying composition, or with layers containing metallic phases, techniques with higher depth resolution and sensitivity to zero-valence metals were necessary. The requirements were met by combining Raman microprobe using different optical configurations and x-ray photoelectron spectroscopy.

  13. Contribution to the study of iron-manganese alloy oxidation in oxygen at high temperatures

    International Nuclear Information System (INIS)

    Olivier, Francoise

    1972-01-01

    This research thesis reports a systematic investigation of the oxidation of three relatively pure iron-manganese alloys in oxygen, under atmospheric pressure, and between 400 and 1000 C, these alloys being annealed as well as work-hardened. It also compares their behaviour with that of non-alloyed iron oxidized under the same conditions. The author describes the experimental techniques and installations, discusses the morphology of oxide films formed under the experimental conditions, discusses the film growth kinetics which is studied by thermogravimetry, proposes interpretations of results, and outlines the influence of manganese addition to iron on iron oxidation

  14. Study on the influence of carbon monoxide to the surface oxide layer of uranium metal

    International Nuclear Information System (INIS)

    Wang Xiaolin; Duan Rongliang; Fu Yibei; Xie Renshou; Zuo Changming; Zhao Chunpei; Chen Hong

    1997-01-01

    The influence of carbon monoxide to the surface oxide layer of uranium metal has been studied by X-ray photoelectron spectroscopy (XPS) and gas chromatography (GC). Carbon monoxide adsorption on the oxide layer resulted in U4f peak shifting to the lower binding energy. The content of oxygen in the oxide is decreased and the atomic ratio (O/U) is decreased by 7.2%. The amount of carbon dioxide in the atmosphere after the surface reaction is increased by 11.0%. The investigation indicates that the surface layer can prevent the further oxidation uranium metal in the atmosphere of carbon monoxide

  15. Study of mechanism involved in synthesis of graphene oxide and reduced graphene oxide from graphene nanoplatelets

    Science.gov (United States)

    Sharma, Bhasha; Shekhar, Shashank; Malik, Parul; Jain, Purnima

    2018-06-01

    Graphene, a wonder material has inspired quest among researchers due to its numerous applications and exceptional properties. This paper highlights the mechanism and chemistry behind the fabrication of graphene oxide by using phosphoric acid. Chemical functionalization is of prime importance which avoids agglomeration of nanoparticles to attain inherent properties. As non-homogeneous dispersion limits its utilization due to interfacial interactions which restrict reactive sites to produce intercalated network. Thus, chemically functionalized graphene leads to stable dispersion and enhances thermal, mechanical and electrical properties of the resultant polymer composite materials. Solubility of graphene in aqueous solution is the major issue because graphene is hydrophobic, to rectify this oxygen containing hydrophilic groups must be introduced to make it compatible and this can be attained by covalent functionalization. Among all nanofiller GO has shown average particle size i.e. 95 nm and highest surface charge density. The characteristic changes were estimated using Raman spectra.

  16. Tratamento famacológico da neuralgia do trigêmeo: revisão sistemática e metanálise Tratamiento famacológico de la neuralgia del trigémino: revisión sistemática y metanálisis Pharmacological treatment of trigeminal neuralgia: systematic review and metanalysis

    Directory of Open Access Journals (Sweden)

    Túlio César Azevedo Alves

    2004-12-01

    medicamentosa sistémica es considerada como el tratamiento de primera línea para esta enfermedad. El objetivo de este estudio fue de evaluar la eficacia, la seguridad y la tolerabilidad de los diversos tratamientos farmacológicos ofrecidos a los pacientes con neuralgia del trigémino, con la finalidad de suministrar evidencias para las recomendaciones de la práctica clínica e identificar las necesidades de pesquisas adicionales. MÉTODO: Fueron analizados ensayos clínicos aleatorios y controlados, publicados hasta julio de 2003, sobre el efecto analgésico de las drogas prescritas en el tratamiento de la neuralgia del trigémino. El análisis estadístico fue realizado con el auxilio del programa Review Manager 4.2.2 (Colaboración Cochrane, 2003. RESULTADOS: Los resultados de la metanálisis sugieren que la carbamazepina es más eficaz que el placebo. En tres estudios controlados comparando la lamotrigina, el topiramato y el cloridrato de proparacaína al placebo, solamente la lamotrigina se mostró superior a él. El dextrometafano fue comparado al lorazepam en dosis bajas, habiendo aumento del dolor con el uso de aquel fármaco. Tres estudios compararon la carbamazepina con la tizanidina, la tocainida y la pimozida, mostrándose apenas la pimozida superior a la carbamazepina. CONCLUSIONES: La carbamazepina continúa como droga de elección para el tratamiento de la neuralgia del trigémino, estando la lamotrigina y la pimozida indicadas en casos refractarios a la terapia convencional. Además, estudios adicionales son necesarios para que se establezcan futuras opciones terapéuticas.BACKGROUND AND OBJECTIVES: Trigeminal neuralgia is a syndrome of chronic pain, characterized by paroxysms of excruciating pain which dramatically affect patients' quality of life. Systemic drug therapy is the first line treatment for this disease. This study aimed at evaluating efficacy, safety and tolerability of several pharmacologic treatments offered to trigeminal neuralgia patients

  17. A Reactive Oxide Overlayer on Rh Nanoparticles during CO Oxidation and Its Size Dependence Studied by in Situ Ambient Pressure XPS

    International Nuclear Information System (INIS)

    Grass, Michael E.; Zhang, Yawen; Butcher, Derek R.; Park, Jeong Y.; Li, Yimin; Bluhm, Hendrik; Bratlie, Kaitlin M.; Zhang, Tianfu; Somorjai, Gabor A.

    2008-01-01

    CO oxidation is one of the most studied heterogeneous reactions, being scientifically and industrially important, particularly for removal of CO from exhaust streams and preferential oxidation for hydrogen purification in fuel cell applications. The precious metals Ru, Rh, Pd, Pt, and Au are most commonly used for this reaction because of their high activity and stability. Despite the wealth of experimental and theoretical data, it remains unclear what is the active surface for CO oxidation under catalytic conditions for these metals. In this communication, we utilize in situ synchrotron ambient pressure X-ray photoelectron spectroscopy (APXPS) to monitor the oxidation state at the surface of Rh nanoparticles during CO oxidation and demonstrate that the active catalyst is a surface oxide, the formation of which is dependent on particle size. The amount of oxide formed and the reaction rate both increase with decreasing particle size.

  18. Infrared absorption study of ammonium uranates and uranium oxide powders formed during their thermal decomposition

    International Nuclear Information System (INIS)

    Rofail, N.H.; ELfekey, S.A.

    1992-01-01

    Ammonium uranates (AU) were precipitated from a nuclear-pure uranyl nitrate solution using different precipitating agents. IR spectra of the obtained uranates and oxides formed during their thermal decomposition have been studied. The results indicated that the precipitating agent, mode of stirring, washing and calcining temperature are important factors for a specific oxide formation.4 FIG., 3 TAB

  19. Mechanistic study of ruthenium (III) catalysed oxidation of L-lysine by ...

    Indian Academy of Sciences (India)

    Administrator

    MS received 15 April 2008; revised 2 July 2008. Abstract. The kinetics of Ru(III) catalysed oxidation of L-lysine by diperiodatoargentate (III) (DPA) in alkaline medium at 298 K and a constant ionic strength of 0⋅50 mol dm. –3 was studied spectrophotometri- cally. The oxidation products are aldehyde (5-aminopentanal) and ...

  20. A computational study of catalysis by gold in applications of CO oxidation

    NARCIS (Netherlands)

    Hussain, A.

    2010-01-01

    Au based catalysts have been extensively studied since Masatake Haruta in Japan discovered that small Au nanoparticles supported on transition metal oxides are exceptionally active catalysts for oxidation reactions at low temperature. However, what makes gold, being inert in the bulk form, active is

  1. Study by electronic microscopy of corrosion features of graphite after hot oxidation (air, 620 C)

    International Nuclear Information System (INIS)

    Jodon de Villeroche, Suzanne

    1968-01-01

    The author reports the study of corrosion features of graphite after hot oxidation in the air at 620 C. It is based on observations made by electronic microscopy. This study comes after another one dedicated to oxidation features obtained by hot corrosion of natural graphite, and aims at comparing pyrolytic graphite before and after irradiation in an atomic pile, and at performing tests on a graphite processed with ozone. After a recall of generalities about natural graphite and of some issues related to hot corrosion of natural graphite, the author presents some characteristics and features of irradiated and non-irradiated pyrolytic graphite. He reports the study of the oxidation of samples of pyrolytic graphite: production of thin lamellae, production of glaze-carbon replicates, oxidation of irradiated and of non-irradiated graphite, healing of irradiation defects, and oxidation of ozone-processed natural graphite [fr

  2. Apparatus for study of transient oxidation of Zircaloy-4 tubing

    International Nuclear Information System (INIS)

    Sagat, S.; Iglesias, F.C.; Newell, G.W.

    1985-11-01

    Complex transient oxidation tests on Zircaloy-4 tubing were performed to provide data for validation of the computer code FROM2. This code was developed to calculate oxygen distribution through oxidized Zircaloy tubing. The test temperature histories consisted of ramp, hold and cool cycles. The heating and cooling rates were in the range of 1 to 100 K/s and the maximum temperature was 1875 K. The apparatus developed to perform these experiments is described. In principle, Joule heating is used to heat the specimen and the temperature is controlled by a computer in conjunction with temperature and SCR power controllers. Using this combination, fast heating and cooling rates were achieved without sacrificing the accuracy of temperature control

  3. Studies of Deactivation of Methanol to Formaldehyde Selective Oxidation Catalyst

    DEFF Research Database (Denmark)

    Raun, Kristian Viegaard; Schumann, Max; Høj, Martin

    Formaldehyde (CH2O) may be synthesized industrially by selective oxidation of methanol over an iron-molybdate (Fe-Mo) oxide catalyst according to: CH3OH + ½O2 →CH2O + H2O. The reaction is normally carried out in a multitubular reactor with excess of air at 250-400 °C (yield = 90-95 %), known...... the activity of the catalyst [2]. Pure MoO3 in itself has low activity. Literature from the last decades agrees that the major reason for the deactivation is loss of molybdenum from the catalyst. Molybdenum forms volatile species with methanol, which can leave behind Mo poor zones. The catalyst is usually...

  4. High pressure structural studies on nanophase praseodymium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Saranya, L. [Jamal Mohamed College, Tiruchirapalli 620020, Tamil Nadu (India); Chandra Shekar, N.V., E-mail: chandru@igcar.gov.in [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu (India); Amirthapandian, S. [Materials Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu (India); Hussain, Shamima [UGC-DAE-CSR node, Kokilamedu 603103, Tamil Nadu (India); Arulraj, A.; Sahu, P. Ch. [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu (India)

    2014-09-15

    The phase stability of nanocrystalline Pr{sub 2}O{sub 3} has been investigated under pressure by in-situ high pressure X-ray diffraction using Mao-Bell type diamond anvil cell. The ambient structure and phase of the praseodymium oxide have been resolved unambiguously using x-ray diffraction, SEM and TEM techniques. Under the action of pressure the cubic phase of the system is retained up to 15 GPa. This is unusual as other isostructural rare earth oxides show structural transformations even at lower pressures. From the best fit to the P–V data with the Murnaghan equation of state yields a bulk modulus of 171 GPa.

  5. Fundamental study on recovery uranium oxide from HEPA filters

    International Nuclear Information System (INIS)

    Izumida, T.; Noguchi, Y.

    1993-01-01

    Large numbers of spent HEPA filters are produced at uranium fuel fabrication facilities. Uranium oxide particles have been collected on these filters. Then, a spent HEPA filter treatment system was developed from the viewpoint of recovering the UO 2 and minimizing the volume. The system consists of a mechanical separation process and a chemical dissolution process. This paper describes the results of fundamental experiments on recovering UO 2 from HEPA filters

  6. Studies of the Tc oxidation states in humic acid solutions

    International Nuclear Information System (INIS)

    Wang Bo; Liu Dejun; Yao Jun

    2010-01-01

    The oxidation state is an important aspect of the speciation of Tc in groundwater that contained organic substances due to it control the precipitation, complexation, sorption and colloid formation behavior of the Tc under HWL geological disposal conditions. In present work, the oxidation states of Tc were investigated using the LaCl 3 coagulation method and solution extraction method in aqueous solutions in which the humic acid concentration range is from 0 to 20 mg L -1 and the Tc (Ⅶ) concentration range is about 10 -8 mol l -1 . The radiocounting of 99 Tc was determined using liquid scintillation spectrometry. The humic acid will influence the radiocounting ratio of 99 Tc apparently, however, the quenching effect can be restrained once keep the volume of the cocktail to about twenty times of the sample volume. The LaCl 3 coagulation methods were carried out for the investigation of Tc oxidation states in humic acid aqueous systems at about pH 8. The tetraphenylarsonium chloride (IPA)-chloroform extraction method was used also simultaneously to investigation the concentrations of Tc (Ⅳ) and Tc (Ⅶ) for the availability of the LaCl 3 precipitation method, and the experimental results demonstrate that tetravalent technetium and pertechnetate concentrations are well agreement with the LaCl 3 precipitation method. These two experimental results demonstrated that Tc (Ⅶ) is very stable in the Tc (Ⅶ)-humic acid system during a 350 days experimental period, and the Tc (Ⅳ) concentrations are very lower, that is indicate that there didn't oxidizing reactions between the Fluka humic acid and Tc (Ⅶ) in aqueous solutions under anaerobic conditions. That is means the presence of humic acids even in anaerobic groundwater is disadvantage for the retardance of radionuclides. (authors)

  7. Studies of Tc oxidation states in humic acid solutions

    International Nuclear Information System (INIS)

    Wang Bo; Liu Dejun; Yao Jun

    2011-01-01

    The oxidation state of Tc is an important aspect of the speciation in groundwater which contained organic substances due to it control the precipitation, complexation, sorption and colloid formation behavior of the Tc under HWL geological disposal conditions. In present work, the oxidation states of Tc were investigated using the LaCl 3 coagulation method and solution extraction method in aqueous solutions in which the humic acid concentration range is from 0 to 20 mg/L and the Tc (VII) concentration is about 10 -8 mol/L. The radiocounting of 99 Tc was determined using liquid scintillation spectrometry. The humic acid will influence the radiocounting ratio of 99 Tc apparently, however, the quenching effect can be restrained once keep the volume of the cocktail to about twenty times of the sample volume. The LaCl 3 coagulation method was carried out for the investigation of Tc oxidation states in humic acid aqueous systems at about pH 8. The tetraphenylarsonium chloride (TPA)-chloroform extraction method was used also simultaneously to investigation the concentrations of Tc (IV) and Tc (VII) for the availability of the LaCl 3 precipitation method, and the experimental results demonstrate that tetravalent technetium and pertechnetate concentration are well agreement with the LaCl 3 precipitation method. These two experimental results demonstrated that Tc (VII) is very stable in the Tc (VII)-humic acid system during a 350 days experimental period, and the Tc (IV) concentrations are very lower, that is indicate that there didn't oxidizing reactions between the Fluka humic acid and Tc (VII) in aqueous solutions under anaerobic conditions. That means the presence of humic acids even in anaerobic groundwater is disadvantage for the retardance of radionuclides. (authors)

  8. Study of Advanced Oxidation System for Water Treatment

    International Nuclear Information System (INIS)

    Widdi Usada; Bambang Siswanto; Suryadi; Agus Purwadi; Isyuniarto

    2007-01-01

    Hygiene water is still a big problem globally as well as energy and food, especially in Indonesia where more than 70 % lived in Java island. One of the efforts in treating hygiene water is to recycle the used water. In this case it is needed clean water technology. Many methods have been done, this paper describes the advanced oxidation technology system based on ozone, titania and plasma discharge. (author)

  9. Study of propane partial oxidation on vanadium-containing catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Komashko, G.A.; Khalamejda, S.V.; Zazhigalov, V.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    The present results indicate that maximum selectivity to acrylic acid can be reached over V-P-Zr-O catalysts. When the hydrocarbon concentration is 5.1 vol.% the selectivity is about 30% at quite high paraffin conversion. Conclusively, some explanations to the observed facts can be given. The V-P-O catalyst promotion with lanthanum by means of mechanochemical treatment is distinguished by the additive uniform spreading all over the matrix surface. Such twophase system is highly active in propane conversion (lanthanum oxide) and further oxidation of the desired products. The similar properties are attributed to V-P-Bi-La-O catalyst. Bismuth, tellurium and zirconium additives having clearly defined acidic properties provoke the surface acidity strengthening and make easier desorption of the acidic product (acrylic acid) from the surface lowering its further oxidation. Additionally, since bismuth and zirconium are able to form phosphates and, according to, to create space limitations for the paraffin molecule movement out of the active group boundaries, this can be one more support in favour of the selectivity increase. With this point of view very interesting results were obtained. It has been shown that the more limited the size of the vanadium unit, the higher the selectivity is. Monoclinic phase AV{sub 2}P{sub 2}O{sub 10} which consists in clusters of four vanadium atoms is sensibly more reactive than the orthorhombic phase consists in V{sub {infinity}} infinite chains. (orig.)

  10. Systematic study of metal-insulator-metal diodes with a native oxide

    Science.gov (United States)

    Donchev, E.; Gammon, P. M.; Pang, J. S.; Petrov, P. K.; Alford, N. McN.

    2014-10-01

    In this paper, a systematic analysis of native oxides within a Metal-Insulator-Metal (MIM) diode is carried out, with the goal of determining their practicality for incorporation into a nanoscale Rectenna (Rectifying Antenna). The requirement of having a sub-10nm oxide scale is met by using the native oxide, which forms on most metals exposed to an oxygen containing environment. This, therefore, provides a simplified MIM fabrication process as the complex, controlled oxide deposition step is omitted. We shall present the results of an investigation into the current-voltage characteristics of various MIM combinations that incorporate a native oxide, in order to establish whether the native oxide is of sufficient quality for good diode operation. The thin native oxide layers are formed by room temperature oxidation of the first metal layer, deposited by magnetron sputtering. This is done in-situ, within the deposition chamber before depositing the second metal electrode. Using these structures, we study the established trend where the bigger the difference in metal workfunctions, the better the rectification properties of MIM structures, and hence the selection of the second metal is key to controlling the device's rectifying properties. We show how leakage current paths through the non-optimised native oxide control the net current-voltage response of the MIM devices. Furthermore, we will present the so-called diode figures of merit (asymmetry, non-linearity and responsivity) for each of the best performing structures.

  11. Systematic study of metal-insulator-metal diodes with a native oxide

    KAUST Repository

    Donchev, E.

    2014-10-07

    © 2014 SPIE. In this paper, a systematic analysis of native oxides within a Metal-Insulator-Metal (MIM) diode is carried out, with the goal of determining their practicality for incorporation into a nanoscale Rectenna (Rectifying Antenna). The requirement of having a sub-10nm oxide scale is met by using the native oxide, which forms on most metals exposed to an oxygen containing environment. This, therefore, provides a simplified MIM fabrication process as the complex, controlled oxide deposition step is omitted. We shall present the results of an investigation into the current-voltage characteristics of various MIM combinations that incorporate a native oxide, in order to establish whether the native oxide is of sufficient quality for good diode operation. The thin native oxide layers are formed by room temperature oxidation of the first metal layer, deposited by magnetron sputtering. This is done in-situ, within the deposition chamber before depositing the second metal electrode. Using these structures, we study the established trend where the bigger the difference in metal workfunctions, the better the rectification properties of MIM structures, and hence the selection of the second metal is key to controlling the device\\'s rectifying properties. We show how leakage current paths through the non-optimised native oxide control the net current-voltage response of the MIM devices. Furthermore, we will present the so-called diode figures of merit (asymmetry, non-linearity and responsivity) for each of the best performing structures.

  12. Ultrathin copper aluminum and nickel aluminide protective oxidation studied with an x-ray photoelectron spectrometer

    Science.gov (United States)

    Moore, J. F.; McCann, M. P.; Pellin, M. J.; Zinovev, A.; Hryn, J. N.

    2003-09-01

    Oxidation in a regime where diffusion is rapid and pressures are low is addressed. Kinetic effects under these conditions are minimized and a protective oxide film of near-equilibrium composition that is a few nanometers thick may form. Ultrathin oxides have great potential for addressing the corrosion resistance of metals, since they do not always suffer stress-induced cracking upon thermal cycling, and can be reformed under high temperature, oxidizing environments. Ultrathin oxide films are also preferable to those on a thick oxide scale for electrochemical applications due to their electrical properties. To study the growth of these oxide films, we have developed a high signal x-ray photoelectron spectrometer. The instrument can measure the near-surface composition during growth under oxygen partial pressures of up to 10-5 mbar and surface temperatures up to 1300 K. Under these conditions, films grow to a level of 3 nm in 1 h. Experiments with Cu-Al alloys show rapid segregation of Al upon oxygen exposure at 875 K, whereas exposures at lower temperatures result in a mixed oxide. With a Ni-Al intermetallic, higher temperatures were needed to preferentially segregate Al. Thermal cycling followed by exposure to chlorine in the same instrument is used as a measure of the degree of corrosion resistance of the oxides in question.

  13. Study Trapped Charge Distribution in P-Channel Silicon-Oxide-Nitride-Oxide-Silicon Memory Device Using Dynamic Programming Scheme

    Science.gov (United States)

    Li, Fu-Hai; Chiu, Yung-Yueh; Lee, Yen-Hui; Chang, Ru-Wei; Yang, Bo-Jun; Sun, Wein-Town; Lee, Eric; Kuo, Chao-Wei; Shirota, Riichiro

    2013-04-01

    In this study, we precisely investigate the charge distribution in SiN layer by dynamic programming of channel hot hole induced hot electron injection (CHHIHE) in p-channel silicon-oxide-nitride-oxide-silicon (SONOS) memory device. In the dynamic programming scheme, gate voltage is increased as a staircase with fixed step amplitude, which can prohibits the injection of holes in SiN layer. Three-dimensional device simulation is calibrated and is compared with the measured programming characteristics. It is found, for the first time, that the hot electron injection point quickly traverses from drain to source side synchronizing to the expansion of charged area in SiN layer. As a result, the injected charges quickly spread over on the almost whole channel area uniformly during a short programming period, which will afford large tolerance against lateral trapped charge diffusion by baking.

  14. Behaviour of zirconium oxidation and is oxide films in alkali halide solutions as studied by electrochemical techniques

    International Nuclear Information System (INIS)

    Saleh, H.E.M.

    1996-01-01

    Study of the properties of Zr electrode and the oxide films that cover the metal surface is of extreme importance due to their wide applications in chemical and nuclear industry. In this thesis the electrochemical behaviour of Zr electrode in alkali halide solutions and with various surface conditions was studied, Also the galvanostatic oxidation of the metal in addition to the open circuit and impedance measurements were employed. Chapter I is a literature survey of the electrochemistry of Zr metal with particular emphasis on the stability and growth process of Zr in different media. Chapter II contains the experimental part, including details of the electrochemical techniques used in the measurements. The electrode impedance was always balanced as a series capacitance Cs and resistance Rs.Chapter III includes the experimental results and discussion. It is divide into sections, A and B. Section A includes the results of some experimental parameters which affect the reactivity of the oxide growth process on the zirconium surface, such as surface pre - treatment, electrolyte composition, the effect of different alkali halide anions, as well as the triiodide ion. 9 tabs.,26 figs.,67 refs

  15. Oxidation study of Cr-Ru hard coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yung-I, E-mail: yichen@mail.ntou.edu.tw; Kuo, Yu-Chu; Chen, Sin-Min

    2012-01-01

    Cr-Ru alloy coatings with Cr content ranging from 47 to 83 at.% were deposited at 400 Degree-Sign C by direct current magnetron co-sputtering with a Ti interlayer on silicon substrates. With a total input power of 300 W, the Cr content in the Cr-Ru coatings increased linearly with the increasing input power of Cr. The intermetallic compound phase Cr{sub 2}Ru with columnar structure was identified for the as-deposited Cr{sub 56}Ru{sub 44} and Cr{sub 65}Ru{sub 35} coatings, resulting in an increase of hardness up to 15-16 GPa. To evaluate the performance of Cr-Ru coatings as a protective coating on glass molding dies, the annealing treatment was conducted at 600 Degree-Sign C in a 50 ppm O{sub 2}-N{sub 2} atmosphere. The outward diffusion and preferential oxidization of Cr in the Cr-Ru coatings resulted in the variations of the crystalline structure, chemical composition distribution, and surface hardness after annealing. X-ray diffraction and transmission electron microscopy (TEM) proved that an oxide scale consisting of Cr{sub 2}O{sub 3} formed on the free surface. Scanning electron microscopy and TEM observed the surface morphology and structural variation. The chemical composition depth profiles were analyzed by Auger electron microscopy, verifying the presence of a Cr-depleted zone beneath the oxide scale. The hardness of Cr{sub 56}Ru{sub 44} and Cr{sub 65}Ru{sub 35} coatings decreased to 11-12 GPa after annealing, accompanied by the replacement of the Cr{sub 2}Ru phase by the Ru phase. - Highlights: Black-Right-Pointing-Pointer We prepared crystalline Cr-Ru alloy coatings by direct current magnetron sputtering. Black-Right-Pointing-Pointer Cr-Ru coatings were annealed at 600 Degree-Sign C for 2 h in a 50 ppm O{sub 2}-N{sub 2} atmosphere. Black-Right-Pointing-Pointer Cr diffused outwardly and oxidized to form a stable and protective oxide scale. Black-Right-Pointing-Pointer The original columnar grains recrystallized to polycrystalline grains.

  16. In situ X-ray powder diffraction studies of the synthesis of graphene oxide and formation of reduced graphene oxide

    International Nuclear Information System (INIS)

    Storm, Mie Møller; Johnsen, Rune E.; Norby, Poul

    2016-01-01

    Graphene oxide (GO) and reduced graphene oxide (rGO) are important materials in a wide range of fields. The modified Hummers methods, for synthesizing GO, and subsequent thermal reduction to rGO, are often employed for production of rGO. However, the mechanism behinds these syntheses methods are still unclear. We present an in situ X-ray diffraction study of the synthesis of GO and thermal reduction of GO. The X-ray diffraction revealed that the Hummers method includes an intercalation state and finally formation of additional crystalline material. The formation of GO is observed during both the intercalation and the crystallization stage. During thermal reduction of GO three stages were observed: GO, a disordered stage, and the rGO stage. The appearance of these stages depends on the heating ramp. The aim of this study is to provide deeper insight into the chemical and physical processes during the syntheses. - Graphical abstract: In situ X-ray diffraction results for of the modified Hummers synthesis and the thermal reduction of graphene oxide, revealing three stages for both syntheses as well as new GO diffraction peaks and unidentified crystalline material for the Hummers synthesis and a disordered stage for the thermal reduction of graphene oxide. Display Omitted - Highlights: • Hummers synthesis consists of three stages: dissolution, intercalation and crystal. • GO is produced early on during the synthesis and display new diffraction peaks. • An unidentified triclinic phase is observed for the Hummers synthesis. • Thermal reduction of GO display three stages: GO, a disordered stage and rGO. • In situ XRD indicate reformation of rGO even for fast heated thermal reduction.

  17. In situ X-ray powder diffraction studies of the synthesis of graphene oxide and formation of reduced graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Storm, Mie Møller, E-mail: mmst@dtu.dk; Johnsen, Rune E.; Norby, Poul

    2016-08-15

    Graphene oxide (GO) and reduced graphene oxide (rGO) are important materials in a wide range of fields. The modified Hummers methods, for synthesizing GO, and subsequent thermal reduction to rGO, are often employed for production of rGO. However, the mechanism behinds these syntheses methods are still unclear. We present an in situ X-ray diffraction study of the synthesis of GO and thermal reduction of GO. The X-ray diffraction revealed that the Hummers method includes an intercalation state and finally formation of additional crystalline material. The formation of GO is observed during both the intercalation and the crystallization stage. During thermal reduction of GO three stages were observed: GO, a disordered stage, and the rGO stage. The appearance of these stages depends on the heating ramp. The aim of this study is to provide deeper insight into the chemical and physical processes during the syntheses. - Graphical abstract: In situ X-ray diffraction results for of the modified Hummers synthesis and the thermal reduction of graphene oxide, revealing three stages for both syntheses as well as new GO diffraction peaks and unidentified crystalline material for the Hummers synthesis and a disordered stage for the thermal reduction of graphene oxide. Display Omitted - Highlights: • Hummers synthesis consists of three stages: dissolution, intercalation and crystal. • GO is produced early on during the synthesis and display new diffraction peaks. • An unidentified triclinic phase is observed for the Hummers synthesis. • Thermal reduction of GO display three stages: GO, a disordered stage and rGO. • In situ XRD indicate reformation of rGO even for fast heated thermal reduction.

  18. Oxidation behaviour of zirconium alloys and their precipitates – A mechanistic study

    International Nuclear Information System (INIS)

    Proff, C.; Abolhassani, S.; Lemaignan, C.

    2013-01-01

    The precipitate oxidation behaviour of binary zirconium alloys containing 1 wt.% Fe, Ni, Cr or 0.6 wt.% Nb was characterised in TEM on FIB prepared transverse sections of the oxide and reported in previous studies [1,2]. In the present study the following alloys: Zr1%Cu, Zr0.5%Cu0.5%Mo and pure Zr are analysed to add to the available information. In all cases, the observed precipitate oxidation behaviour in the oxide close to the metal-oxide interface could be described either with delayed oxidation with respect to the matrix or simultaneous oxidation as the surrounding zirconium matrix. Attempt was made to explain these observations, with different parameters such as precipitate size and structure, composition and thermodynamic properties. It was concluded that the thermodynamics with the new approach presented could explain most precisely their behaviour, considering the precipitate stoichiometry and the free energy of oxidation of the constituting elements. The surface topography of the oxidised materials, as well as the microstructure of the oxide presenting microcracks have been examined. A systematic presence of microcracks above the precipitates exhibiting delayed oxidation has been found; the height of these crack calculated using the Pilling–Bedworth ratios of different phases present, can explain their origin. The protrusions at the surface in the case of materials containing large precipitates can be unambiguously correlated to the presence of these latter, and the height can be correlated to the Pilling–Bedworth ratios of the phases present as well as the diffusion of the alloying elements to the surface and their subsequent oxidation. This latter behaviour was much more considerable in the case of Fe and Cu with Fe showing systematically diffusion to the outer surface.

  19. Growth of micrometric oxide layers for the study of metallic surfaces decontamination by laser

    Science.gov (United States)

    Carvalho, Luisa; Pacquentin, Wilfried; Tabarant, Michel; Maskrot, Hicham; Semerok, Alexandre

    2017-09-01

    The nuclear industry produces a wide range of radioactive waste in term of level of hazard, contaminants and material. For metallic equipment like steam generators, the radioactivity is mainly located in the oxide surface. In order to study and develop techniques for dismantling and for decontamination in a safe way, it is important to have access to oxide layers with a representative distribution of non-radioactive contaminants. We propose a method of formation of oxide layer on stainless steel 304L with europium (Eu) as contaminant marker. In this method, an Eu-solution is sprayed on the stainless steel samples. The specimen are firstly treated with a pulsed nanosecond laser and secondly the steel samples are exposed to a 600°C furnace for various durations in order to grow an oxide layer. The oxide structure and in-depth distribution of Eu in the oxide layer are analysed by scanning electron microscopy coupled with energy dispersive X-ray microanalyzer, and by glow discharge optical emission or mass spectrometry. The oxide layers were grown to thicknesses in the range of 200 nm to 4.5 μm regarding to the laser treatment parameters and the heating duration. These contaminated oxides have a `duplex structure' with a mean weight percentage of 0.5% of europium in the volume of the oxide layer. It appears that europium implementation prevents the oxide growth by furnace but has no impact on laser heating. These oxide layers are used to study the decontamination of metallic surfaces such as stainless steel 304L using a nanosecond pulsed laser.

  20. Growth of micrometric oxide layers for the study of metallic surfaces decontamination by laser

    Directory of Open Access Journals (Sweden)

    Carvalho Luisa

    2017-01-01

    Full Text Available The nuclear industry produces a wide range of radioactive waste in term of level of hazard, contaminants and material. For metallic equipment like steam generators, the radioactivity is mainly located in the oxide surface. In order to study and develop techniques for dismantling and for decontamination in a safe way, it is important to have access to oxide layers with a representative distribution of non-radioactive contaminants. We propose a method of formation of oxide layer on stainless steel 304L with europium (Eu as contaminant marker. In this method, an Eu-solution is sprayed on the stainless steel samples. The specimen are firstly treated with a pulsed nanosecond laser and secondly the steel samples are exposed to a 600°C furnace for various durations in order to grow an oxide layer. The oxide structure and in-depth distribution of Eu in the oxide layer are analysed by scanning electron microscopy coupled with energy dispersive X-ray microanalyzer, and by glow discharge optical emission or mass spectrometry. The oxide layers were grown to thicknesses in the range of 200 nm to 4.5 μm regarding to the laser treatment parameters and the heating duration. These contaminated oxides have a ‘duplex structure’ with a mean weight percentage of 0.5% of europium in the volume of the oxide layer. It appears that europium implementation prevents the oxide growth by furnace but has no impact on laser heating. These oxide layers are used to study the decontamination of metallic surfaces such as stainless steel 304L using a nanosecond pulsed laser.

  1. A study of internal oxidation in carburized steels by glow discharge optical emission spectroscopy and scanning electron microscopy

    CERN Document Server

    An, X; Rainforth, W M; Chen, L

    2003-01-01

    The internal oxidation of Cr-Mn carburizing steel was studied. Internal oxidation was induced using a commercial carburizing process. Sputter erosion coupled with glow discharge optical emission spectroscopy (GDOES) was used to determine the depth profile elemental distribution within the internal oxidation layer (<10 mu m). In addition, scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) studies were carried out on selected sputter eroded surfaces. Oxide type was identified primarily by transmission electron microscopy (TEM). The carburized surface was found to consist of a continuous oxide layer, followed by a complex internal oxidation layer, where Cr and Mn oxides were found to populate grain boundaries in a globular form in the near surface region. At greater depths (5-10 mu m), Si oxides formed as a grain boundary network. The internal oxides (mainly complex oxides) grew quickly during the initial stages of the carburizing process (2 h, 800 deg. C+3 h, 930 deg. C). G...

  2. A study on the improvement of oxidation resistance of OAE-added stainless steels for high temperature applications

    International Nuclear Information System (INIS)

    Kim, Dae Hwan; Kim, Gil Moo

    1996-01-01

    Since the manufacturing temperature of stainless steels is relatively high, oxidation at the elevated temperature becomes important. The chemical and physical properties of the protective oxide film which was formed on the stainless steels at high temperature for the oxidation resistance are important in determining the rate of oxidation and the life of equipment exposed to high temperature oxidizing environments. In this study, the oxidation behavior of STS 309S and STS 409L added by a small amount of oxygen active element(each + 0.5wt% Hf and Y) was studied to improve oxidation resistance. In the cyclic oxidation, while OAE-free specimens showed relatively poor oxidation resistance due to spallations and cracks of Cr-rich oxide layer, OAE-added specimens improved cyclic oxidation resistance assumably due to constant oxidation rate with stable oxide layers at high temperature. Especially Hf improved cyclic oxidation resistance by forming Cr-rich oxide layer preventing internal oxidation in STS 309S. (author)

  3. Spectro-electrochemical and DFT study of tenoxicam metabolites formed by electrochemical oxidation

    International Nuclear Information System (INIS)

    Ramírez-Silva, M.T.; Guzmán-Hernández, D.S.; Galano, A.; Rojas-Hernández, A.; Corona-Avendaño, S.; Romero-Romo, M.; Palomar-Pardavé, M.

    2013-01-01

    Highlights: • Tenoxicam deprotonation and electrochemical oxidation were studied. • Both spectro-electrochemical and theoretical DFT studies were considered. • It was found that the ampholitic species of tenoxicam is a zwitterion. • Electrochemical oxidation of tenoxicam yields two non-electroactive products. • The nature of these fragments was further confirmed by a chromatography study. -- Abstract: From experimental (spectro-electrochemical) and theoretical (DFT) studies, the mechanisms of tenoxicam deprotonation and electrochemical oxidation were assessed. From these studies, new insights on the nature of the ampholitic species involved during tenoxicam's deprotonation in aqueous solution are presented; see scheme A. Moreover, it is shown that, after the analysis of two different reaction schemes that involve up to 10 different molecules and 12 reaction paths, the electrochemical oxidation of tenoxicam, yields two non-electroactive products that are predominately formed by its fragmentation, after the loss of two electrons. The nature of these fragments was further confirmed by a chromatography study

  4. Comparative Study of Antidiabetic Activity and Oxidative Stress Induced by Zinc Oxide Nanoparticles and Zinc Sulfate in Diabetic Rats.

    Science.gov (United States)

    Nazarizadeh, Ali; Asri-Rezaie, Siamak

    2016-08-01

    In the current study, antidiabetic activity and toxic effects of zinc oxide nanoparticles (ZnO) were investigated in diabetic rats compared to zinc sulfate (ZnSO4) with particular emphasis on oxidative stress parameters. One hundred and twenty male Wistar rats were divided into two healthy and diabetic groups, randomly. Each major group was further subdivided into five subgroups and then orally supplemented with various doses of ZnO (1, 3, and 10 mg/kg) and ZnSO4 (30 mg/kg) for 56 consecutive days. ZnO showed greater antidiabetic activity compared to ZnSO4 evidenced by improved glucose disposal, insulin levels, and zinc status. The altered activities of erythrocyte antioxidant enzymes as well as raised levels of lipid peroxidation and a marked reduction of total antioxidant capacity were observed in rats receiving ZnO. ZnO nanoparticles acted as a potent antidiabetic agent, however, severely elicited oxidative stress particularly at higher doses.

  5. Evaluation of tumoral enhancement by superparamagnetic iron oxide particles: comparative studies with ferumoxtran and anionic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Brillet, P-Y.; Gazeau, F.; Luciani, A.; Bessoud, B.; Cuenod, C.-A.; Siauve, N.; Pons, J.-N.; Poupon, J.; Clement, O.

    2005-01-01

    This study was designed to compare tumor enhancement by superparamagnetic iron oxide particles, using anionic iron oxide nanoparticles (AP) and ferumoxtran. In vitro, relaxometry and media with increasing complexity were used to assess the changes in r2 relaxivity due to cellular internalization. In vivo, 26 mice with subcutaneously implanted tumors were imaged for 24 h after injection of particles to describe kinetics of enhancement using T1 spin echo, T2 spin echo, and T2 fast spin echo sequences. In vitro, the r2 relaxivity decreased over time (0-4 h) when AP were uptaken by cells. The loss of r2 relaxivity was less pronounced with long (Hahn Echo) than short (Carr-Purcell-Meiboom-Gill) echo time sequences. In vivo, our results with ferumoxtran showed an early T2 peak (1 h), suggesting intravascular particles and a second peak in T1 (12 h), suggesting intrainterstitial accumulation of particles. With AP, the late peak (24 h) suggested an intracellular accumulation of particles. In vitro, anionic iron oxide nanoparticles are suitable for cellular labeling due to a high cellular uptake. Conversely, in vivo, ferumoxtran is suitable for passive targeting of tumors due to a favorable biodistribution. (orig.)

  6. Positron annihilation induced Auger electron spectroscopic studies of oxide surfaces

    Science.gov (United States)

    Nadesalingam, Manori

    2005-03-01

    Defects on oxide surfaces are well known to play a key role in catalysis. TiO2, MgO, SiO2 surfaces were investigated using Time-Of-Flight Positron induced Auger Electron Spectroscopy (TOF-PAES). Previous work in bulk materials has demonstrated that positrons are particularly sensitive to charged defects. In PAES energetic electron emission results from Auger transitions initiated by annihilation of core electrons with positrons trapped in an image-potential well at the surface. Annealed samples in O2 environment show a strong Auger peak of Oxygen. The implication of these results will be discussed

  7. Development studies of a novel wet oxidation process

    International Nuclear Information System (INIS)

    Rogers, T.W.; Dhooge, P.M.

    1995-01-01

    Many DOE waste streams and remediates contain complex and variable mixtures of organic compounds, toxic metals, and radionuclides. These materials are often dispersed in organic or inorganic matrices, such as personal protective equipment, various sludges, soils, and water. Incineration and similar combustive processes do not appear to be viable options for treatment of these waste streams due to various considerations. There is a need for non-combustion processes with a wide application range to treat the large majority of these waste forms. The non-combustion process should also be safe, effective, cost-competitive, permit-able, and preferrably mobile. This paper describes the DETOX process of organic waste oxidation

  8. Field studies of HT oxidation and dispersion in the environment

    International Nuclear Information System (INIS)

    Brown, R.M.; Ogram, G.L.; Spencer, F.S.; Ontario Hydro, Toronto, ON

    1988-10-01

    A tracer quantity of 3.54 TBq tritiated hydrogen (HT) was released into the atmosphere at a Chalk River, Ontario field site to determine the behaviour of HT in the environment. The primary objective was to establish the oxidation rate of HT to tritiated water (HTO) in air, soil and vegetation compartments. HTO/HT atmospheric concentration ratios observed during the release ranged from 0.14 x 10 -4 at 5 m to 7.0 x 10 -4 at 400 m distance from the release point indicating an effective oxidation rate of about 1.5% h -1 . Gas phase oxidation in the atmosphere would be less than this effective rate. Results confirm that surface soils play the dominant role in converting HT to HTO. Soil HT deposition velocities were between 2.7 x 10 -4 and 11 x 10 -4 m s -1 for an open field of varied composition, and between 3.3 x 10 -4 and 12 x 10 -4 m s -1 for a conifer forest. Soil HTO loss rates were initially 1 to 3 % h -1 averaged over the first 24 h after release. Vegetation tissue-free water tritium (TFWT) resulted from uptake of soil HTO and exchange with atmospheric HTO vapour. Upper limit HT deposition velocities to vegetation measured as TFWT in 5 species were 0.23 x 10 -7 to 6 x 10 -7 m s -1 expressed on a leaf area basis. TFWT loss rates were 5.2 to 8.1 % h -1 from about 12 to 48 h after release with low activity rain and 0.42 to 0.56 % h -1 from about 48 to 335 h. Vegetation organically-bound tritium/TFWT specific activity ratios (Bq g -1 H) were about 0.1 initially, increasing to 16 after 113 days as TFWT specific activity declined more rapidly than that of OBT. The effective HT oxidation rate, deposition velocities and HTO loss rates were in good agreement with a 1986 HT field release and previous laboratory experiments

  9. Experimental kinetic study and modeling of calcium oxide carbonation

    International Nuclear Information System (INIS)

    Rouchon, L.

    2012-01-01

    Anthropogenic carbon dioxide (CO 2 ) emissions, major contributors to the greenhouse effect, are considered as the main cause of global warming. So, decrease of CO 2 emitted by large industrial combustion sources or power plants, is an important scientific goal. One of the approaches is based on CO 2 separation and capture from flue gas, followed by sequestration in a wide range of geological formations. In this aim, CO 2 is captured by sorbents like calcium oxide (CaO) in multi-cycle process of carbonation/de-carbonation. However, it was shown that the most important limitations of such process are related to the reversibility of reaction. CaO rapidly loses activity towards CO 2 , so the maximum extent of carbonation decreases as long as the number of cycles increases. In order to well understand the processes and parameters influencing the capture capacity of CaO-based sorbents, it appears important to get details on the kinetic law governing the reaction, which have not been really studied up to now. To investigate this reaction, CaO carbonation kinetics was followed by means of thermogravimetric analysis (TGA) on divided materials. Special care was given to the validation of the usual kinetic assumptions such as steady state and rate-determining step assumptions. The aim was to obtain a model describing the reaction in order to explain the influence of intensive variables such as carbonation temperature and CO 2 partial pressure. TGA curves obtained under isothermal and isobaric conditions showed an induction period linked to the nucleation process and a strong slowing down of the reaction rate once a given fractional conversion was reached. Both phenomena were observed to depend on carbonation temperature and CO 2 partial pressure. To explain these results, the evolution of texture and microstructure of the solid during the reaction was regarded as essential. Reaction at the grain scale induces a volume increase from CaO to CaCO 3 which causes a change in the

  10. Preliminary study on the existence characteristics of rare earth elements in the interstratified oxidized zone

    International Nuclear Information System (INIS)

    Wang Jinping

    2006-10-01

    There were few of studies on rare earth elements (REE) in sandstone hosted uranium deposits, except the study of sediments source tracing and REE distribution modalities. Based on the study of existence characteristics of REE in subzones of interstratified oxidized zone in Shihongtan uranium deposit, Tuha basin, the possible migration features of REE was traced, and the significance of ΣREE, LREE/HREE ratios and δEu, δCe value during the interstratified oxidation were illustrated. (authors)

  11. Study mechanism of growth and spallation of oxide scales formed after T91 steel oxidation in water vapor at 550 C

    International Nuclear Information System (INIS)

    Demizieux, Marie-Christine

    2015-01-01

    In the framework of the development of Generation IV reactors and specifically in the new Sodium Fast Reactor (SFR) project, Fe-9Cr ferritic-martensitic steels are candidates as structural materials for steam generators. Indeed, Fe-9Cr steels are already widely used in high temperature steam environments - like boilers and steam turbines- for their combination of creep strength and high thermal properties. Many studies have been focused on Fe-9Cr steels oxidation behavior between 550 C-700 C.Depending on the oxidizing environment, formation of a triplex (Fe-Cr spinel/magnetite/hematite) or duplex (Fe-Cr spinel/magnetite) oxide scales are reported.. Besides, for long time exposure in steam, the exfoliation of oxide scales can cause serious problems such as tube obstruction and steam turbine erosion. Consequently, this work has been dedicated to study, on the one hand the oxidation kinetics of T91 steel in water vapor environments, and on the other hand, the mechanisms leading to the spallation of the oxide scale. Oxidation tests have been carried out at 550 C in pure water vapor and in Ar/D_2O/H_2 environments with different hydrogen contents. Based on an analytical resolution, a quantitative modeling has shown that the 'available space model' proposed in the literature for duplex oxide scale formation well reproduces both scales growth kinetics and spinel oxide stoichiometry. Then, oxidized samples have been precisely characterized and it turns out that buckling then spalling of the oxide scale is always located in the magnetite layer. Voids observed in the magnetite layer are major initiation sites of de-cohesion of the outer oxide scale. A mechanism of formation of these voids has been proposed, in accordance with the mechanism of duplex scale formation. The derived model based on the assumption that vacancies accumulate where the iron vacancies flux divergence is maximal gives a good estimation of the location of pores inside the magnetite layer. Then, in order

  12. In Situ Study of Thermal Stability of Copper Oxide Nanowires at Anaerobic Environment

    Directory of Open Access Journals (Sweden)

    Lihui Zhang

    2014-01-01

    Full Text Available Many metal oxides with promising electrochemical properties were developed recently. Before those metal oxides realize the use as an anode in lithium ion batteries, their thermal stability at anaerobic environment inside batteries should be clearly understood for safety. In this study, copper oxide nanowires were investigated as an example. Several kinds of in situ experiment methods including in situ optical microscopy, in situ Raman spectrum, and in situ transmission electron microscopy were adopted to fully investigate their thermal stability at anaerobic environment. Copper oxide nanowires begin to transform as copper(I oxide at about 250°C and finish at about 400°C. The phase transformation proceeds with a homogeneous nucleation.

  13. Kinetic studies on the degradation of crystal violet by the Fenton oxidation process.

    Science.gov (United States)

    Wu, H; Fan, M M; Li, C F; Peng, M; Sheng, L J; Pan, Q; Song, G W

    2010-01-01

    The degradation of dye crystal violet (CV) by Fenton oxidation process was investigated. The UV-Vis spectrogram has shown that CV can be degraded effectively by Fenton oxidation process. Different system variables namely initial H(2)O(2) concentration, initial Fe(2 + ) concentration and reaction temperature, which have effect on the degradation of CV by Fenton oxidation process, have been studied systematically. The degradation kinetics of CV was also elucidated based on the experimental data. The degradation of CV obeys the first-order reaction kinetics. The kinetic model can be described as k=1.5 exp(-(7.5)/(RT))[H(2)O(2)](0)(0.8718)[Fe(2+)](0)(0.5062). According to the IR spectrogram, it is concluded that the benzene ring of crystal violet has been destroyed by Fenton oxidation. The result will be useful in treating dyeing wastewater containing CV by Fenton oxidation process.

  14. An international multicentre study on the allergenic activity of air-oxidized R-limonene

    DEFF Research Database (Denmark)

    Bråred Christensson, Johanna; Andersen, Klaus Ejner; Bruze, Magnus

    2013-01-01

    Background. Limonene is a common fragrance terpene that, in its pure form, is not allergenic or is a very weak allergen. However, limonene autoxidizes on air exposure, and the oxidation products can cause contact allergy. Oxidized R-limonene has previously been patch tested in multicentre studies......, giving 2-3% positive patch test reactions in consecutive patients. Objectives. To investigate whether oxidized R-limonene 3.0% in petrolatum, with a stable concentration of the main haptens, limonene hydroperoxides (Lim-OOHs), could be a useful tool for the detection of contact allergy...... in an international setting. Methods. Oxidized R-limonene 3.0% (Lim-OOHs 0.33%) pet. was tested in 2900 consecutive dermatitis patients in Denmark, the United Kingdom, Singapore, Spain, Sweden, and Australia. Results. Overall, 5.2% (range 2.3-12.1%) of the patients showed a positive patch test reaction to oxidized R...

  15. Single-molecule study of oxidative enzymatic deconstruction of cellulose.

    Science.gov (United States)

    Eibinger, Manuel; Sattelkow, Jürgen; Ganner, Thomas; Plank, Harald; Nidetzky, Bernd

    2017-10-12

    LPMO (lytic polysaccharide monooxygenase) represents a unique paradigm of cellulosic biomass degradation by an oxidative mechanism. Understanding the role of LPMO in deconstructing crystalline cellulose is fundamental to the enzyme's biological function and will help to specify the use of LPMO in biorefinery applications. Here we show with real-time atomic force microscopy that C1 and C4 oxidizing types of LPMO from Neurospora crassa (NcLPMO9F, NcLPMO9C) bind to nanocrystalline cellulose with high preference for the very same substrate surfaces that are also used by a processive cellulase (Trichoderma reesei CBH I) to move along during hydrolytic cellulose degradation. The bound LPMOs, however, are immobile during their adsorbed residence time ( ~ 1.0 min for NcLPMO9F) on cellulose. Treatment with LPMO resulted in fibrillation of crystalline cellulose and strongly ( ≥ 2-fold) enhanced the cellulase adsorption. It also increased enzyme turnover on the cellulose surface, thus boosting the hydrolytic conversion.Understanding the role of enzymes in biomass depolymerization is essential for the development of more efficient biorefineries. Here, the authors show by atomic force microscopy the real-time mechanism of cellulose deconstruction by lytic polysaccharide monooxygenases.

  16. Component mode synthesis methods for 3-D heterogeneous core calculations applied to the mixed-dual finite element solver MINOS

    International Nuclear Information System (INIS)

    Guerin, P.; Baudron, A.M.; Lautard, J.J.; Van Criekingen, S.

    2007-01-01

    This paper describes a new technique for determining the pin power in heterogeneous three-dimensional calculations. It is based on a domain decomposition with overlapping sub-domains and a component mode synthesis (CMS) technique for the global flux determination. Local basis functions are used to span a discrete space that allows fundamental global mode approximation through a Galerkin technique. Two approaches are given to obtain these local basis functions. In the first one (the CMS method), the first few spatial eigenfunctions are computed on each sub-domain, using periodic boundary conditions. In the second one (factorized CMS method), only the fundamental mode is computed, and we use a factorization principle for the flux in order to replace the higher-order Eigenmodes. These different local spatial functions are extended to the global domain by defining them as zero outside the sub-domain. These methods are well fitted for heterogeneous core calculations because the spatial interface modes are taken into account in the domain decomposition. Although these methods could be applied to higher-order angular approximations-particularly easily to an SPN approximation-the numerical results we provide are obtained using a diffusion model. We show the methods' accuracy for reactor cores loaded with uranium dioxide and mixed oxide assemblies, for which standard reconstruction techniques are known to perform poorly. Furthermore, we show that our methods are highly and easily parallelizable. (authors)

  17. comparative study between different oxidizing agents to prepare radioiodinated alpha fetoprotein (AFP)

    International Nuclear Information System (INIS)

    El-Kolaly, M.T.; Ragab, M.T.; El-Mohty, A.A.; Sallam, K.M.; Arief, M.H.

    2004-01-01

    the aim of the present study was designed to prepare four different preparation of radioiodinated alpha fetoprotein ( 125 I-Afp) using different oxidizing agents. the oxidizing agents were chloramine-T (Ch-T), lodogen (1,3,4 , 6-tetrachloro 3 α ,6α diphenyl glycoluril ), N-bromosuccinimide (NBS) and lactoperoxidase (LPS). the product was purified by gel filtration using sephadex G-25. then the tracers obtained were tested by radioimmunoassay (RIA) technique. different affecting factors were extensively studied including reaction time, reaction volume, oxidizing agent content and Ph of reaction. it was found that the Ch-T method is the best one

  18. High-Resolution Electron Energy Loss Studies of Oxygen, Hydrogen, Nitrogen, Nitric Oxide, and Nitrous Oxide Adsorption on Germanium Surfaces.

    Science.gov (United States)

    Entringer, Anthony G.

    The first high resolution electron energy loss spectroscopy (HREELS) studies of the oxidation and nitridation of germanium surfaces are reported. Both single crystal Ge(111) and disordered surfaces were studied. Surfaces were exposed to H, O_2, NO, N _2O, and N, after cleaning in ultra-high vacuum. The Ge surfaces were found to be non-reactive to molecular hydrogen (H_2) at room temperature. Exposure to atomic hydrogen (H) resulted hydrogen adsorption as demonstrated by the presence of Ge-H vibrational modes. The HREEL spectrum of the native oxide of Ge characteristic of nu -GeO_2 was obtained by heating the oxide to 200^circC. Three peaks were observed at 33, 62, and 106 meV for molecular oxygen (O_2) adsorbed on clean Ge(111) at room temperature. These peaks are indicative of dissociative bonding and a dominant Ge-O-Ge bridge structure. Subsequent hydrogen exposure resulted in a shift of the Ge-H stretch from its isolated value of 247 meV to 267 meV, indicative of a dominant +3 oxidation state. A high density of dangling bonds and defects and deeper oxygen penetration at the amorphous Ge surface result in a dilute bridge structure with a predominant +1 oxidation state for similar exposures. Molecules of N_2O decompose at the surfaces to desorbed N_2 molecules and chemisorbed oxygen atoms. In contrast, both oxygen and nitrogen are detected at the surfaces following exposure to NO molecules. Both NO and N_2O appear to dissociate and bond at the top surface layer. Molecular nitrogen (N_2) does not react with the Ge surfaces, however, a precursor Ge nitride is observed at room temperature following exposure to nitrogen atoms and ions. Removal of oxygen by heating of the NO-exposed surface to 550^circC enabled the identification of the Ge-N vibrational modes. These modes show a structure similar to that of germanium nitride. This spectrum is also identical to that of the N-exposed surface heated to 550^circC. Surface phonon modes of the narrow-gap semiconducting

  19. Palladium nanoparticles anchored on graphene nanosheets: Methanol, ethanol oxidation reactions and their kinetic studies

    KAUST Repository

    Nagaraju, Doddahalli H.; Devaraj, Sappani; Balaya, Palani

    2014-01-01

    nanosheets. The electro-catalytic activity of Gra/Pd nanocomposites toward methanol and ethanol oxidation in alkaline medium was evaluated by cyclic voltammetric studies. 1:1 Gra/Pd nanocomposite exhibited good electro-catalytic activity and efficient

  20. A sensitivity study of the oxidation of compressed natural gas on platinum

    KAUST Repository

    Badra, Jihad; Masri, Assaad Rachid; Farooq, Aamir

    2013-01-01

    This paper presents a sensitivity study for the oxidation of methane (CH4) over platinum (Pt). Some dominant reactions in the CH 4-Pt surface chemistry were identified and the rates of these reactions were subsequently modified to enhance

  1. Synchrotron x-ray reflectivity study of oxidation/passivation of copper and silicon

    International Nuclear Information System (INIS)

    Chu, Y.; Nagy, Z.; Parkhutik, V.; You, H.

    1999-01-01

    Synchrotron x-ray-scattering technique studies of copper and silicon electrochemical interfaces are reported. These two examples illustrate the application of synchrotron x-ray techniques for oxidation, passivation, and dissolution of metals and semiconductors

  2. Synchrotron x-ray reflectivity study of oxidation/passivation of copper and silicon.

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Y.; Nagy, Z.; Parkhutik, V.; You, H.

    1999-07-21

    Synchrotron x-ray-scattering technique studies of copper and silicon electrochemical interfaces are reported. These two examples illustrate the application of synchrotron x-ray techniques for oxidation, passivation, and dissolution of metals and semiconductors.

  3. Kinetic studies of electrochemical generation of Ag(II) ion and catalytic oxidation of selected organics

    International Nuclear Information System (INIS)

    Zawodzinski, C.; Smith, W.H.; Martinez, K.R.

    1993-01-01

    The goal of this research is to develop a method to treat mixed hazardous wastes containing selected organic compounds and heavy metals, including actinide elements. One approach is to destroy the organic via electrochemical oxidation to carbon dioxide, then recover the metal contaminants through normally accepted procedures such as ion exchange, precipitation, etc. The authors have chosen to study the electrochemical oxidation of a simple alcohol, iso-propanol. Much of the recent work reported involved the use of an electron transfer mediator, usually the silver(I)/(II) redox couple. This involved direct electrochemical generation of the mediator at the anode of a divided cell followed by homogeneous reaction of the mediator with the organic compound. In this study the authors have sought to compare the mediated reaction with direct electrochemical oxidation of the organic. In addition to silver(I)/(II) they also looked at the cobalt(II)/(III) redox coupled. In the higher oxidation state both of these metal ions readily hydrolyze in aqueous solution to ultimately form insoluble oxide. The study concluded that in a 6M nitric acid solution at room temperature iso-propanol can be oxidized to carbon dioxide and acetic acid. Acetic acid is a stable intermediate and resists further oxidation. The presence of Co(III) enhances the rate or efficiency of the reaction

  4. An experimental and modeling study of diethyl carbonate oxidation

    KAUST Repository

    Nakamura, Hisashi; Curran, Henry J.; Polo-Có rdoba, Á ngel David; Pitz, William J.; Dagaut, P.; Togbé , Casimir; Sarathy, Mani; Mehl, Marco; Agudelo, John Ramiro; Bustamante, Felipe

    2015-01-01

    Diethyl carbonate (DEC) is an attractive biofuel that can be used to displace petroleum-derived diesel fuel, thereby reducing CO2 and particulate emissions from diesel engines. A better understanding of DEC combustion characteristics is needed to facilitate its use in internal combustion engines. Toward this goal, ignition delay times for DEC were measured at conditions relevant to internal combustion engines using a rapid compression machine (RCM) and a shock tube. The experimental conditions investigated covered a wide range of temperatures (660-1300K), a pressure of 30bar, and equivalence ratios of 0.5, 1.0 and 2.0 in air. To provide further understanding of the intermediates formed in DEC oxidation, species concentrations were measured in a jet-stirred reactor at 10atm over a temperature range of 500-1200K and at equivalence ratios of 0.5, 1.0 and 2.0. These experimental measurements were used to aid the development and validation of a chemical kinetic model for DEC.The experimental results for ignition in the RCM showed near negative temperature coefficient (NTC) behavior. Six-membered alkylperoxy radical (RO˙2) isomerizations are conventionally thought to initiate low-temperature branching reactions responsible for NTC behavior, but DEC has no such possible 6- and 7-membered ring isomerizations. However, its molecular structure allows for 5-, 8- and 9-membered ring RO˙2 isomerizations. To provide accurate rate constants for these ring structures, ab initio computations for RO˙2⇌Q˙OOH isomerization reactions were performed. These new RO˙2 isomerization rate constants have been implemented in a chemical kinetic model for DEC oxidation. The model simulations have been compared with ignition delay times measured in the RCM near the NTC region. Results of the simulation were also compared with experimental results for ignition in the high-temperature region and for species concentrations in the jet-stirred reactor. Chemical kinetic insights into the

  5. An experimental and modeling study of diethyl carbonate oxidation

    KAUST Repository

    Nakamura, Hisashi

    2015-04-01

    Diethyl carbonate (DEC) is an attractive biofuel that can be used to displace petroleum-derived diesel fuel, thereby reducing CO2 and particulate emissions from diesel engines. A better understanding of DEC combustion characteristics is needed to facilitate its use in internal combustion engines. Toward this goal, ignition delay times for DEC were measured at conditions relevant to internal combustion engines using a rapid compression machine (RCM) and a shock tube. The experimental conditions investigated covered a wide range of temperatures (660-1300K), a pressure of 30bar, and equivalence ratios of 0.5, 1.0 and 2.0 in air. To provide further understanding of the intermediates formed in DEC oxidation, species concentrations were measured in a jet-stirred reactor at 10atm over a temperature range of 500-1200K and at equivalence ratios of 0.5, 1.0 and 2.0. These experimental measurements were used to aid the development and validation of a chemical kinetic model for DEC.The experimental results for ignition in the RCM showed near negative temperature coefficient (NTC) behavior. Six-membered alkylperoxy radical (RO˙2) isomerizations are conventionally thought to initiate low-temperature branching reactions responsible for NTC behavior, but DEC has no such possible 6- and 7-membered ring isomerizations. However, its molecular structure allows for 5-, 8- and 9-membered ring RO˙2 isomerizations. To provide accurate rate constants for these ring structures, ab initio computations for RO˙2⇌Q˙OOH isomerization reactions were performed. These new RO˙2 isomerization rate constants have been implemented in a chemical kinetic model for DEC oxidation. The model simulations have been compared with ignition delay times measured in the RCM near the NTC region. Results of the simulation were also compared with experimental results for ignition in the high-temperature region and for species concentrations in the jet-stirred reactor. Chemical kinetic insights into the

  6. Electrogeneration and study of oxide layer on AISI 316 L steel

    International Nuclear Information System (INIS)

    Otero, T.F.; Mateo, M.L.

    1989-01-01

    It has been studied by impedance technique the properties of oxide layers electrogenerated on a stainless steel by cyclic voltammetry. Also, it has been studied the behavior of these layers in chloride media applying a fast corrosion test. The results have been compared with such obtained in mild steel. UV - Vis reflectance and FTIR spectroscopies have been applied to know about the oxide composition [pt

  7. Study on radioprotective efficacy of indazolone derivative on γ-radiation induced oxidative stress

    International Nuclear Information System (INIS)

    Mohan, B.J.; Sarojini, B.K.; Narayana, B.; Sanjeev, Ganesh

    2014-01-01

    The present study describes the potency of 6-(4-bromophenyl)-4-(4-fluorophenyl)-1,2,4,5-tetrahydro-3H-indazol-3-one (IND) as radioprotective agent. Drosophila melanogaster was used as a model organism for the study. Oxidative stress was induced by irradiating the flies with 6 Gy γ-radiation.The control and irradiated flies were assayed for oxidative stress markers namely, lipid peroxidation (MDA), SOD and CATenzyme. (author)

  8. Transport of electrons in lead oxide studied by CELIV technique

    International Nuclear Information System (INIS)

    Semeniuk, O; Juska, G; Oelerich, J O; Jandieri, K; Baranovskii, S D; Reznik, A

    2017-01-01

    Although polycrystalline lead oxide (PbO) has a long history of application in optoelectronics and imaging, the transport mechanism for electrons in this material has not yet been clarified. Using the photo-generated charge extraction by linear increasing voltage (photo-CELIV) technique, we provide the temperature- and field-dependences of electron mobility in poly-PbO. It is found that electrons undergo dispersive transport, i.e. their mobility decreases in the course of time. Multiple trapping of electrons from the conduction band into the developed band tail is revealed as the dominant transport mechanism. This differs dramatically from the dispersive transport of holes in the same material, dominated by topological factors and not by energy disorder. (paper)

  9. Ferric oxide quantum dots in stable phosphate glass system and their magneto-optical study

    Energy Technology Data Exchange (ETDEWEB)

    Garaje, Sunil N.; Apte, Sanjay K. [Nanocomposite Group, Centre for Materials for Electronics Technology (C-MET), Department of Electronics and Information Technology (DeitY), Government of India, Panchawati, Off Pashan Road, Pune 411008 (India); Kumar, Ganpathy [Department of Electrical and Computer Engineering, Tennessee Technological University, 1 William L. Jones Drive, Cookeville, TN 38505 (United States); Panmand, Rajendra P.; Naik, Sonali D. [Nanocomposite Group, Centre for Materials for Electronics Technology (C-MET), Department of Electronics and Information Technology (DeitY), Government of India, Panchawati, Off Pashan Road, Pune 411008 (India); Mahajan, Satish M., E-mail: smahajan@tntech.edu [Department of Electrical and Computer Engineering, Tennessee Technological University, 1 William L. Jones Drive, Cookeville, TN 38505 (United States); Chand, Ramesh [Ministry of Communications and Information Technology, Department of Electronics and Information Technology (DeitY), Electronics Niketan, 6, CGO Complex, New Delhi 110003 (India); Kale, Bharat B., E-mail: bbkale@cmet.gov.in [Nanocomposite Group, Centre for Materials for Electronics Technology (C-MET), Department of Electronics and Information Technology (DeitY), Government of India, Panchawati, Off Pashan Road, Pune 411008 (India)

    2013-02-15

    Graphical abstract: We report synthesis of ferric oxide embedded low melting phosphate glass nanocomposite and also the effect of ferric oxide nanoparticles (NCs) content on the optical and magneto-optical properties of the glasses. Faraday rotation of the glass nanocomposites was measured and showed variation in Verdet constant with concentration of ferric oxide. Interestingly, the host glass itself showed fairly good Verdet constant (11.5°/T cm) and there is a threefold enhancement in the Verdet constant of ferric oxide quantum dot-glass nanocomposite. Highlights: ► We synthesize ferric oxide embedded low melting stable phosphate glass nanocomposite. ► Glasses doped with 0.25 and 2% ferric oxide show particle size in the range of 4–12 nm. ► The host phosphate glass itself shows fairly good Verdet constant (11.5°/T cm). ► Glasses doped with 0.25% ferric oxide show high Verdet constant (30.525°/T cm). ► The as synthesis glasses may have potential application in magneto optical devices. -- Abstract: Herein, we report the synthesis of ferric oxide embedded low melting phosphate glass nanocomposite and also the effect of ferric oxide nanoparticles content on the optical and magneto-optical properties of the glasses. The optical study clearly showed red shift in optical cut off with increasing ferric oxide concentration. The band gap of the host glass was observed to be 3.48 eV and it shifted to 3.14 eV after doping with ferric oxide. The glasses doped with 0.25 and 2% ferric oxide showed particle size of 4–6 nm and 8–12 nm, respectively. Faraday rotation of the glass nanocomposites was measured and showed variation in the Verdet constant as per increasing concentration of ferric oxide. Interestingly, the host glass itself showed fairly good Verdet constant (11.5°/T cm) and threefold enhancement was observed in the Verdet constant of ferric oxide quantum dot-glass nanocomposite.

  10. Actinide oxides synthesis in molten chloride. Structural studies and reaction mechanisms

    International Nuclear Information System (INIS)

    Vigier, J.F.

    2012-01-01

    Pyrochemical processes are studied as potential alternatives to hydrochemical processes for spent nuclear fuel treatment. The CEA pyrochemical process led to a molten LiCl-CaCl 2 (30-70% mol) salt at 700 C with solubilized actinides at the oxidation state (III). The study developed in this thesis concerns actinide oxides synthesis in this media for nuclear fuel re-fabrication. This synthesis was done by wet argon sparging. First, this conversion method is described for neodymium (III) and cerium (III) co-conversion. The conversion rates are around 99.9%. The obtained powders contain mixed oxychloride Ce 1-x Nd x OCl as main component, with a small amount of mixed oxide Ce 1-x Nd x O 2-0,5x for the high cerium ratio. A second oxychloride CeIV(Nd 0.7 Ce 0.3 ) III O 3 Cl is obtained in specific conditions and in very low quantity. The structure of this oxychloride is described in this study. The partially oxidative property of the conversion method induces the oxidation of a part of cerium (III) to oxidation state (IV). In the case of uranium (III) conversion by wet argon sparging, all the uranium is oxidized and give the oxide UO 2 as single compound. The conversion rate for this element is over 99.9% in the molten chloride, but significant amount of uranium is lost by volatilization during the conversion. The study shows the oxygen sensitivity of uranium during the conversion, inducing oxidation over the oxidation state (IV), and giving UO 2+x or uranate CaUO 4 . As a consequence, oxygen led to calcium pollution in the precipitate. Finally, the U(III) and Pu(III) co-conversion study shows the highest precipitation sensitivity of uranium (III) in comparison with plutonium (III), responsible of a successive conversion of the two elements, giving an oxide mixture of UO 2 et PuO 2 with quantitative conversion rate. Surprisingly, the conversion of Pu(III) in the same conditions led to a mixture of PuO 2 and PuOCl, characteristic of a partial oxidation from Pu (III) to Pu

  11. Oxidation of InP nanowires: a first principles molecular dynamics study.

    Science.gov (United States)

    Berwanger, Mailing; Schoenhalz, Aline L; Dos Santos, Cláudia L; Piquini, Paulo

    2016-11-16

    InP nanowires are candidates for optoelectronic applications, and as protective capping layers of III-V core-shell nanowires. Their surfaces are oxidized under ambient conditions which affects the nanowire physical properties. The majority of theoretical studies of InP nanowires, however, do not take into account the oxide layer at their surfaces. In this work we use first principles molecular dynamics electronic structure calculations to study the first steps in the oxidation process of a non-saturated InP nanowire surface as well as the properties of an already oxidized surface of an InP nanowire. Our calculations show that the O 2 molecules dissociate through several mechanisms, resulting in incorporation of O atoms into the surface layers. The results confirm the experimental observation that the oxidized layers become amorphous but the non-oxidized core layers remain crystalline. Oxygen related bonds at the oxidized layers introduce defective levels at the band gap region, with greater contributions from defects involving In-O and P-O bonds.

  12. Further studies on 4-hydroxy-3-methoxyphenylglycol oxidation in humans: effect of pool expansion and stereochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Mardh, G.

    1983-08-01

    The in vivo oxidation of the norepinephrine metabolite 4-hydroxy-3-methoxyphenylglycol (HMPG) to 4-hydroxy-3-methoxymandelic acid was studied in man with two different doses of deuterium-labeled HMPG and a tracer dose of (/sup 14/C)HMPG. HMPG oxidation appeared to be dose-dependent with an oxidation of 62-70% for doses below or equal to 2.2 mumol. With the use of a capillary column coated with an optically active phase (Chirasil-Val) and gas chromatography mass-spectrometry the human urinary excretions of the two stereoisomers of deuterium-labelled HMPG (free + conjugates) were found to be equal.

  13. XPS and SEM studies of chromium oxide films chemically formed on stainless steel 316 L

    International Nuclear Information System (INIS)

    Stefanov, P.; Marinova, T.

    2000-01-01

    The structure and composition of chromium oxide films formed on stainless steel by immersion in a chromium electrolyte have been studied by SEM and XPS. Cr 2 O 3 crystallites in the range 30-150 nm are fully developed and cover the whole surface. The chemical composition in the depth and the thickness of the oxide layer have been determined by XPS sputter profiles. The oxide film can be described within the framework of a double layer consisting of a thin outer hydrated layer and an inner layer of Cr 2 O 3 . (orig.)

  14. Comparative ion insertion study into a nanostructured vanadium oxide in aqueous salt solutions

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Q.; Ren, S. L.; Zukowski, J.; Pomeroy, M.; Soghomonian, V., E-mail: soghomon@vt.edu [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2014-07-07

    We present a comparative study for the electrochemical insertion of different cations into a nanostructured vanadium oxide material. The oxide is hydrothemally synthesized and electrically characterized by variable temperature measurements. The electrochemical reactions are performed in aqueous chloride solutions of lithium, sodium, potassium, and ammonium, and the electrochemical behavior of various cycles are correlated with visual changes in the vanadium oxide nanosheets as observed by scanning electron microscopy. We note an increase in the specific charge per cycle in the cases of sodium and ammonium ions only, correlated with minimal physical changes to the nanosheets. The differing behavior of the various ions has implications for their use in electrical energy storage applications.

  15. Study on the surface oxidation resistance of uranium metal in the atmosphere of carbon monoxide

    International Nuclear Information System (INIS)

    Wang Xiaolin; Fu Yibei; Xie Renshou

    1999-01-01

    The surface reactions of different layers on uranium metal with carbon monoxide at 25, 80 and 200 degree C are studied by X-ray photoelectron spectroscopy (XPS). The experimental results show that the carbon monoxide is adsorbed on the surface oxide layer of uranium and interacted each other. The content of oxygen in the surface oxide and O/U ratio are decreased with increasing the exposure of carbon monoxide to the surface layer. The effect of reduction on the metal surface is more obviously with a higher temperature and increasing of layer thickness. The investigation indicates the uranium metal has resistance to further oxidation in the atmosphere of carbon monoxide

  16. Study of the Rancimat test method in measuring the oxidation stability of biodiesel ester and blends

    Energy Technology Data Exchange (ETDEWEB)

    Berthiaume, D.; Tremblay, A. [Oleotek Inc., Thetford Mines, PQ (Canada)

    2006-11-15

    This paper provided details of a study conducted to examine the oxidation stability of biodiesel blends. The study tested samples of canola oil, soybean oil, fish oil, yellow grease, and tallow. The EN 14112 (Rancimat) method was used to compare oxidation stability results obtained in previous tests conducted in the United States and Europe. The aim of the study was also to evaluate the influence of peroxide value (PV), acid value (AV) and feedstock source on the the oxidative stability of different samples. The study also evaluated the possibility of developing a validated test method developed from the EN 14112 methods to specifically consider biodiesel blends. Results of the study indicated that the Rancimat method was not suitable for measuring the oxidation stability of biodiesels blended with petrodiesels. No direct correlation between oxidative stability and PV or AV was observed. It was concluded that fatty acid distribution was not a principal factor in causing changes in oxidation stability. 22 refs., 3 tabs., 1 fig.

  17. Contribution to the study of the oxidation reaction of the carbon oxide in contact with catalysts issued from the decomposition of nickel hydro-aluminates at various temperatures

    International Nuclear Information System (INIS)

    Samaane, Mikhail

    1966-01-01

    Addressing the study of the oxidation reaction of carbon oxide which produces carbon dioxide, this research thesis reports the study of this reaction in presence of catalysts (2NiO + Al 2 O 3 , NiAl 2 O 4 and NiO + NiAl 2 O 4 ) issued from the decomposition of nickel hydro-aluminates at different temperatures. The first part describes experimental techniques and the nature of materials used in this study. The second part reports the study of the catalytic activity of the 2NiO+Al 2 O 3 catalyst during the oxidation of CO. Preliminary studies are also reported: structure and texture of nickel hydro-aluminate which is the raw material used to produce catalysts, activation of this compound to develop the catalytic activity in CO oxidation, chemisorption of CO, O 2 and CO 2 on the 2NiO+Al 2 O 3 solid, interaction of adsorbed gases at the solid surface, and kinetic study of the oxidation reaction. The third part reports the study of the catalytic activity in the oxidation reaction of CO of spinel catalysts (NiAl 2 O 4 and NiO+NiAl 2 O 4 ) obtained by calcination of nickel hydro-aluminates at high temperature. The formation of the spinel phase, the chemisorption of CO, O 2 and CO 2 on NiAl 2 O 4 , and the kinetic of the oxidation reaction are herein studied

  18. Corrosion mechanisms of zirconium alloys - study of the initial oxidation kinetics and of the mechanical behaviour of the metal/oxide system

    International Nuclear Information System (INIS)

    Parise, M.

    1996-12-01

    Nuclear fuel claddings are made of zirconium alloys. The conditions of use lead the cladding oxidize outside. The so-formed layers behaves like a thermal barrier and prevents from using oxidized claddings with an oxide thickness larger than 100 μm. The oxidation kinetic is approximately cubic for oxide thicknesses smaller than about 2μm, linear beyond. A kinetic model has been proposed which estimates the post-transition growth rate from the kinetic parameters of the pre-transition state and morphological features of post-transition layers. This work aims at providing the necessary elements to validate this model and studying the layers around the kinetic transition, in order to determine whether the oxidation mechanisms before and after the transition are similar. Thicknesses of the 50 - 500 nm range of the oxide layers are measured by an optical method; pre-transition kinetics are thus precisely determined. The effect of the composition, the thermal treatment and the presence of oxygen in solid solution is studied. The morphological and crystallographic study of the layers show that they exhibit a lot of similarities before and after the kinetic transition. The results concerning the kinetic aspects and the morphology of the post-transition layers point out that the proposed model leads to realistic post-transition growth rates. Furthermore, the kinetic transition corresponds to the appearance of cracks in the oxide layer. The mechanical behaviour of the metal/oxide system has been modelled at different scales. When the specific behaviours of the metal and the oxide are taken into account together with the interface geometry, radial stresses appear, which are high enough to locally open cracks. The appearance and localization of cracks depend on both the interface geometry and the stress distribution in the metal/oxide system. (author)

  19. Depression and oxidative stress: results from a meta-analysis of observational studies.

    Science.gov (United States)

    Palta, Priya; Samuel, Laura J; Miller, Edgar R; Szanton, Sarah L

    2014-01-01

    To perform a systematic review and meta-analysis that quantitatively tests and summarizes the hypothesis that depression results in elevated oxidative stress and lower antioxidant levels. We performed a meta-analysis of studies that reported an association between depression and oxidative stress and/or antioxidant status markers. PubMed and EMBASE databases were searched for articles published from January 1980 through December 2012. A random-effects model, weighted by inverse variance, was performed to pool standard deviation (Cohen's d) effect size estimates across studies for oxidative stress and antioxidant status measures, separately. Twenty-three studies with 4980 participants were included in the meta-analysis. Depression was most commonly measured using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria. A Cohen's d effect size of 0.55 (95% confidence interval = 0.47-0.63) was found for the association between depression and oxidative stress, indicating a roughly 0.55 of 1-standard-deviation increase in oxidative stress among individuals with depression compared with those without depression. The results of the studies displayed significant heterogeneity (I(2) = 80.0%, p < .001). A statistically significant effect was also observed for the association between depression and antioxidant status markers (Cohen's d = -0.24, 95% confidence interval = -0.33 to -0.15). This meta-analysis observed an association between depression and oxidative stress and antioxidant status across many different studies. Differences in measures of depression and markers of oxidative stress and antioxidant status markers could account for the observed heterogeneity. These findings suggest that well-established associations between depression and poor heath outcomes may be mediated by high oxidative stress.

  20. Comparative study of the addition compounds between lanthanides methane sulfonates (III) and aromatic amino-oxides as ligands

    International Nuclear Information System (INIS)

    Rosario Matos, J. do.

    1989-01-01

    The main goal of this thesis is to further develop the studies on the preparation and characterization of addition compounds obtained from the reaction of lanthanide methane sulfonates and aromatic amino oxides as ligands, pyridine-N-oxides as the picoline-N-oxides (2-pic NO, 3-pic NO and 4-picNO) in order to make a comparative study. (author)

  1. Assessment of oxidative stress markers in recurrent pregnancy loss: a prospective study.

    Science.gov (United States)

    Yiyenoğlu, Özgür Bilgin; Uğur, Mete Gürol; Özcan, Hüseyin Çağlayan; Can, Günay; Öztürk, Ebru; Balat, Özcan; Erel, Özcan

    2014-06-01

    To determine the levels of oxidative stress markers in recurrent pregnancy loss using a novel automated method. 30 pregnant women in their first trimester with a history of recurrent pregnancy loss (RPL) and 30 healthy pregnant women were enrolled in this prospective controlled study. Total antioxidant capacity (TAC), total oxidant level (TOL) and oxidative stress index (OSI) in maternal serum were measured using the more recently designated Erel method. We observed statistically significant increased TOL and OSI levels in patient group (p = 0.032, p = 0.007, respectively). We also demonstrated statistically significant decreased TAC in pregnant women who had a history of RPL (p = 0.013). Our results support the concept that oxidative stress plays a central role in the etiopathogenesis of RPL. Further studies to evaluate the predictive role of TAC, TOL, OSI levels using Erel method are needed.

  2. Catalytic oxidation using nitrous oxide

    Directory of Open Access Journals (Sweden)

    Juan Carlos Beltran-Prieto

    2017-01-01

    Full Text Available Nitrous oxide is a very inert gas used generally as oxidant as it offers some advantage compared with other oxidants such as O2 but a considerably higher temperature (> 526 °C is often required. For particular cases such as the oxidation of sugar alcohols, especially for the oxidation of primary alcohols to aldehydes, N2O has the advantage over O2 of a higher reaction selectivity. In the present paper we present the modelling of oxidation reaction of sugar alcohols using an oxidizing agent in low concentrations, which is important to suppress subsequent oxidation reactions due to the very low residual concentrations of the oxidizing agent. For orientation experiments we chose nitrous oxide generated by thermal decomposition of ammonium nitrate. Kinetic modeling of the reaction was performed after determination of the differential equations that describe the system under study.

  3. Conductivity study of nitrogen-doped calcium zinc oxide prepared by spray pyrolysis

    International Nuclear Information System (INIS)

    Hsu, Yu-Ting; Lan, Wen-How; Huang, Kai-Feng; Lin, Jia-Ching; Chang, Kuo-Jen

    2016-01-01

    In this study, the spray pyrolysis method was used to prepare unintentionally doped and nitrogen-doped calcium zinc oxide films by using zinc acetate, calcium nitrate precursor, and ammonium acetate precursor. Morphological and structural analyses were conducted using scanning electron microscopy and X-ray diffraction. The results indicated that film grain size decreased as the nitrogen doping was increased. Both calcium oxide and zinc oxide structures were identified in the unintentionally doped calcium zinc oxide. When nitrogen doping was introduced, the film mainly exhibited a zinc oxide structure with preferred (002) and (101) orientations. The concentration and mobility were investigated using a Hall measurement system. P-type films with a mobility and concentration of 10.6 cm"2 V"−"1 s"−"1 and 2.8×10"1"7 cm"−"3, respectively, were obtained. Moreover, according to a temperature-dependent conductivity analysis, an acceptor state with activation energy 0.266 eV dominated the p-type conduction for the unintentionally doped calcium zinc oxide. By contrast, a grain boundary with a barrier height of 0.274–0.292 eV dominated the hole conduction for the nitrogen-doped calcium zinc oxide films.

  4. Electron Band Alignment at Interfaces of Semiconductors with Insulating Oxides: An Internal Photoemission Study

    Directory of Open Access Journals (Sweden)

    Valeri V. Afanas'ev

    2014-01-01

    Full Text Available Evolution of the electron energy band alignment at interfaces between different semiconductors and wide-gap oxide insulators is examined using the internal photoemission spectroscopy, which is based on observations of optically-induced electron (or hole transitions across the semiconductor/insulator barrier. Interfaces of various semiconductors ranging from the conventional silicon to the high-mobility Ge-based (Ge, Si1-xGex, Ge1-xSnx and AIIIBV group (GaAs, InxGa1-xAs, InAs, GaP, InP, GaSb, InSb materials were studied revealing several general trends in the evolution of band offsets. It is found that in the oxides of metals with cation radii larger than ≈0.7 Å, the oxide valence band top remains nearly at the same energy (±0.2 eV irrespective of the cation sort. Using this result, it becomes possible to predict the interface band alignment between oxides and semiconductors as well as between dissimilar insulating oxides on the basis of the oxide bandgap width which are also affected by crystallization. By contrast, oxides of light elements, for example, Be, Mg, Al, Si, and Sc exhibit significant shifts of the valence band top. General trends in band lineup variations caused by a change in the composition of semiconductor photoemission material are also revealed.

  5. Experimental Study of the Swirling Oxidizer Flow in HTPB/N2O Hybrid Rocket Motor

    Directory of Open Access Journals (Sweden)

    Mohammad Mahdi Heydari

    2017-01-01

    Full Text Available Effects of swirling oxidizer flow on the performance of a HTPB/N2O Hybrid rocket motor were studied. A hybrid propulsion laboratory has been developed, to characterize internal ballistics characteristics of swirl flow hybrid motors and to define the operating parameters, like fuel regression rate, specific impulse, and characteristics velocity and combustion efficiency. Primitive variables, like pressure, thrust, temperature, and the oxidizer mass flow rate, were logged. A modular motor with 70 mm outer diameter and variable chamber length is designed for experimental analysis. The injector module has four tangential injectors and one axial injector. Liquid nitrous oxide (N2O as an oxidizer is injected at the head of combustion chamber into the motor. The feed system uses pressurized air as the pressurant. Two sets of tests have been performed. Some tests with axial and tangential oxidizer injection and a test with axial oxidizer injection were done. The test results show that the fuel grain regression rate has been improved by applying tangential oxidizer injection at the head of the motor. Besides, it was seen that combustion efficiency of motors with the swirl flow was about 10 percent more than motors with axial flow.

  6. High-pressure Moessbauer study of perovskite iron oxides

    CERN Document Server

    Kawakami, T; Sasaki, T; Kuzushita, K; Morimoto, S; Endo, S; Kawasaki, S; Takano, M

    2002-01-01

    The perovskite oxides CaFeO sub 3 and La sub 1 sub / sub 3 Sr sub 2 sub / sub 3 FeO sub 3 have been investigated by high-pressure sup 5 sup 7 Fe Moessbauer spectroscopy. The critical temperatures of the charge disproportionation (CD) and the magnetic order (MO) have been determined as a function of pressure. In CaFeO sub 3 the CD (2Fe sup 4 sup + -> Fe sup 3 sup + + Fe sup 5 sup +) occurs at an almost constant temperature of 290 K in the pressure range of 0-17 GPa. Above 20 GPa, the CD is suppressed. The MO temperature of 125 K at an ambient pressure rises to 300 K at 34 GPa. In La sub 1 sub / sub 3 Sr sub 2 sub / sub 3 FeO sub 3 the CD (3Fe sup 1 sup 1 sup / sup 3 sup + -> 2Fe sup 3 sup + + Fe sup 5 sup +) and the MO occur at the same temperature up to 21 GPa, which decreases from 207 to 165 K with increasing pressure. Above 25 GPa, however, the MO temperature rises above 400 K.

  7. Development studies for a novel wet oxidation process. Phase 2

    International Nuclear Information System (INIS)

    1994-07-01

    DETOX SM is a catalyzed wet oxidation process which destroys organic materials in an acidic water solution of iron at 373 to 473 K. The solution can be used repeatedly to destroy great amounts of organic materials. Since the process is conducted in a contained vessel, air emissions from the process can be well controlled. The solution is also capable of dissolving and concentrating many heavy and radioactive metals for eventual stabilization and disposal. The Phase 2 effort for this project is site selection and engineering design for a DETOX demonstration unit. Site selection was made using a set of site selection criteria and evaluation factors. A survey of mixed wastes at DOE sites was conducted using the Interim Mixed Waste Inventory Report. Sites with likely suitable waste types were identified. Potential demonstration sites were ranked based on waste types, interest, regulatory needs, scheduling, ability to provide support, and available facilities. Engineering design for the demonstration unit is in progress and is being performed by Jacobs Applied Technology. The engineering design proceeded through preliminary process flow diagrams (PFDs), calculation of mass and energy balances for representative waste types, process and instrumentation diagrams (P and IDs), preparation of component specifications, and a firm cost estimate for fabrication of the demonstration unit

  8. X-Ray Photoemission Study of the Oxidation of Hafnium

    International Nuclear Information System (INIS)

    Chourasia, R.; Hickman, J.L.; Miller, R.L.; Nixon, G.A.; Seabolt, M.A.

    2011-01-01

    About 20 angstrom of hafnium were deposited on silicon substrates using the electron beam evaporation technique. Two types of samples were investigated. In one type, the substrate was kept at the ambient temperature. After the deposition, the substrate temperature was increased to 100, 200, and 300 degree C. In the other type, the substrate temperature was held fixed at some value during the deposition. For this type, the substrate temperatures used were 100, 200, 300, 400, 500, 550, and 600 degree C. The samples were characterized in situ by the technique of X-ray photoelectron spectroscopy. No trace of elemental hafnium is observed in the deposited overlayer. Also, there is no evidence of any chemical reactivity between the overlayer and the silicon substrate over the temperature range used. The hafnium overlayer shows a mixture of the dioxide and the suboxide. The ratio of the suboxide to dioxide is observed to be more in the first type of samples. The spectral data indicate that hafnium has a strong affinity for oxygen. The overlayer gets completely oxidized to form HfO 2 at substrate temperature around 300 degree C for the first type of samples and at substrate temperature greater than 550 degree C for the second type

  9. X-Ray Photoemission Study of the Oxidation of Hafnium

    Directory of Open Access Journals (Sweden)

    A. R. Chourasia

    2009-01-01

    Full Text Available About 20 Å of hafnium were deposited on silicon substrates using the electron beam evaporation technique. Two types of samples were investigated. In one type, the substrate was kept at the ambient temperature. After the deposition, the substrate temperature was increased to 100, 200, and 300∘C. In the other type, the substrate temperature was held fixed at some value during the deposition. For this type, the substrate temperatures used were 100, 200, 300, 400, 500, 550, and 600∘C. The samples were characterized in situ by the technique of X-ray photoelectron spectroscopy. No trace of elemental hafnium is observed in the deposited overlayer. Also, there is no evidence of any chemical reactivity between the overlayer and the silicon substrate over the temperature range used. The hafnium overlayer shows a mixture of the dioxide and the suboxide. The ratio of the suboxide to dioxide is observed to be more in the first type of samples. The spectral data indicate that hafnium has a strong affinity for oxygen. The overlayer gets completely oxidized to form HfO2 at substrate temperature around 300∘C for the first type of samples and at substrate temperature greater than 550∘C for the second type.

  10. Kinetic study on anaerobic oxidation of methane coupled to denitrification.

    Science.gov (United States)

    Yu, Hou; Kashima, Hiroyuki; Regan, John M; Hussain, Abid; Elbeshbishy, Elsayed; Lee, Hyung-Sool

    2017-09-01

    Monod kinetic parameters provide information required for kinetic analysis of anaerobic oxidation of methane coupled to denitrification (AOM-D). This information is critical for engineering AOM-D processes in wastewater treatment facilities. We first experimentally determined Monod kinetic parameters for an AOM-D enriched culture and obtained the following values: maximum specific growth rate (μ max ) 0.121/d, maximum substrate-utilization rate (q max ) 28.8mmol CH 4 /g cells-d, half maximum-rate substrate concentration (K s ) 83μΜ CH 4 , growth yield (Y) 4.76gcells/mol CH 4 , decay coefficient (b) 0.031/d, and threshold substrate concentration (S min ) 28.8μM CH 4 . Clone library analysis of 16S rRNA and mcrA gene fragments suggested that AOM-D reactions might have occurred via the syntrophic interaction between denitrifying bacteria (e.g., Ignavibacterium, Acidovorax, and Pseudomonas spp.) and hydrogenotrophic methanogens (Methanobacterium spp.), supporting reverse methanogenesis-dependent AOM-D in our culture. High μ max and q max , and low K s for the AOM-D enrichment imply that AOM-D could play a significant role in mitigating atmospheric methane efflux. In addition, these high kinetic features suggest that engineered AOM-D systems may provide a sustainable alternative to nitrogen removal in wastewater treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Pulse radiolysis studies concerning oxidative degradation processes in linear polymers

    International Nuclear Information System (INIS)

    Schnabel, Wolfram

    1986-01-01

    On the basis of pulse radiolysis experiments carried out with various polymers in dilute solution three modes of action of molecular oxygen, 0 2 , can be discriminated with respect to main-chain scission: (a) 0 2 acts as a promoter, (b) 0 2 acts as an inhibitor, and (c) 0 2 acts as a fixing agent for main-chain breaks. The promoting mode of action (a) is due to the inhibition of simultaneously occurring intermolecular crosslinking (DNA, polymethylvinylketone) and/or to the combination of peroxyl radicals with the subsequent formation of readily decomposing oxyl radicals (polyethylene oxide, polyacrylamide, polyvinylpyrrolidone, polyribouridylic acid, polyriboadenylic acid, polyribocytidylic acid). The inhibiting mode of action (b) pertains to the reaction of 0 2 with macroradicals that otherwise undergo main-chain rupture (amylose polymethylmethacrylate). Fixing of main-chain ruptures (mode c) becomes important, if macroradicals generated by a very fast rupture of bonds in the main-chain, are prone to recombine quickly. This mode of action was evidenced in the case of polybutenesulfone where main-chain scission involves the extrusion of small segments of the chain. (author)

  12. Polycrystalline oxides formation during transient oxidation of (001) Cu-Ni binary alloys studied by in situ TEM and XRD

    International Nuclear Information System (INIS)

    Yang, J.C.; Li, Z.Q.; Sun, L.; Zhou, G.W.; Eastman, J.A.; Fong, D.D.; Fuoss, P.H.; Baldo, P.M.; Rehn, L.E.; Thompson, L.J.

    2009-01-01

    The nucleation and growth of Cu 2 O and NiO islands due to oxidation of Cu x Ni 1-x (001) films were monitored, at various temperatures, by in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM) and in situ synchrotron X-ray diffraction (XRD). In remarkable contrast to our previous observations of Cu and Cu-Au oxidation, irregular-shaped polycrystalline oxide islands formed with respect to the Cu-Ni alloy film, and an unusual second oxide nucleation stage was noted. In situ XRD experiments revealed that NiO formed first epitaxially, then other orientations appeared, and finally polycrystalline Cu 2 O developed as the oxidation pressure was increased. The segregation of Ni and Cu towards or away, respectively, from the alloy surface during oxidation could disrupt the surface and cause polycrystalline oxide formation.

  13. Application of in-beam perturbed angular distribution to the study of high-Tc oxides

    International Nuclear Information System (INIS)

    Komori, Fumio; Katsumoto, Shingo; Kobayashi, Shun-ichi; Ikehata, Seiichiro; Ikeda, Nobuo; Hashimoto, Osamu; Fukuda, Tomokazu; Nomura, Toru; Yamazaki, Toshimitsu.

    1990-04-01

    The time differential perturbed angular distribution method was applied to the study of high-T c oxides. Spin rotation signals of the 19 F isomer (τ = 128 nsec) produced from oxygen nuclei via 16 O(α,p) 19 F were observed in various high-T c oxides above T c . The internal field was determined with the accuracy of about 1%. This method is an alternative to the 17 O substituted NMR. (author)

  14. Effect of liver disease on dextromethorphan oxidation capacity and phenotype: a study in 107 patients.

    OpenAIRE

    Larrey, D; Babany, G; Tinel, M; Freneaux, E; Amouyal, G; Habersetzer, F; Letteron, P; Pessayre, D

    1989-01-01

    1. The O-demethylation of dextromethorphan to dextrorphan exhibits a genetically-controlled polymorphism, co-segregating with that of debrisoquine hydroxylation. Dextromethorphan has been proposed as a test compound to assess drug oxidation polymorphism. 2. We studied the effects of liver disease of varying severity on dextromethorphan oxidation capacity. Phenotyping was performed using the urinary dextromethorphan/dextrorphan metabolic ratio after oral administration of 40 mg dextromethorpha...

  15. Comparative study of oxidation in canned foods with a combination of vegetables and covering oils

    OpenAIRE

    E. Bravi; A. Mangione; O. Marconi; G. Perretti

    2015-01-01

    The effects of sunflower (SFO), extra-virgin olive (EVO), and soybean oils (SBO), in combination with canned aubergins and dried tomatoes were studied during an accelerated shelf-life trial. Hydrolytic and oxidative quality parameters was determined and a sensorial test was run. For both canned vegetables, the SBO showed greater resistance to the oxidation at the end of the shelflife trial. The SBO in both vegetables yielded similar results for peroxide formation, whereas a reduced formation ...

  16. Adsorption and revaporisation studies on iodine oxide aerosols deposited on containment surface materials in LWR

    Energy Technology Data Exchange (ETDEWEB)

    Tietze, S.; Foreman, M.R.StJ.; Ekberg, C. [Chalmers Univ. of Technology, Goeteborg (Sweden); Kaerkelae, T.; Auvinen, A.; Tapper, U.; Lamminmaeki, S.; Jokiniemi, J. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2012-12-15

    During a hypothetical severe nuclear accident, the radiation field will be very high in the nuclear reactor containment building. As a result gaseous radiolysis products will be formed. Elemental iodine can react in the gaseous phase with ozone to form solid iodine oxide aerosol particles (iodine oxide). Within the AIAS (Adsorption of Iodine oxide Aerosols on Surfaces) project the interactions of iodine oxide (IOx) aerosols with common containment surface materials were investigated. Common surface materials in Swedish and Finnish LWRs are Teknopox Aqua V A paint films and metal surfaces such as Cu, Zn, Al and SS, as well as Pt and Pd surfaces from hydrogen recombiners. Non-radioactive and {sup 131}I labelled iodine oxide aerosols were produced with the EXSI CONT facility from elemental iodine and ozone at VTT Technical Research Centre of Finland. The iodine oxide deposits were analysed with microscopic and spectroscopic measurement techniques to identify the kind of iodine oxide formed and if a chemical conversion on the different surface materials occurs. The revaporisation behaviour of the deposited iodine oxide aerosol particles from the different surface materials was studied under the influence of heat, humidity and gamma irradiation at Chalmers University of Technology, Sweden. Studies on the effects of humidity were performed using the FOMICAG facility, while heat and irradiation experiments were performed in a thermostated heating block and with a gammacell 22 having a dose rate of 14 kGy/h. The revaporisation losses were measured using a HPGe detector. The revaporisated {sup 131}I species from the surfaces were chemically tested for elemental iodine formation. The parameter dominating the degradation of the produced iodine oxide aerosols was humidity. Cu and Zn surfaces were found to react with iodine from the iodine oxide aerosols to form iodides, while no metal iodides were detected for Al and SS samples. Most of the iodine oxide aerosols are assumed to

  17. Adsorption and revaporisation studies on iodine oxide aerosols deposited on containment surface materials in LWR

    International Nuclear Information System (INIS)

    Tietze, S.; Foreman, M.R.StJ.; Ekberg, C.; Kaerkelae, T.; Auvinen, A.; Tapper, U.; Lamminmaeki, S.; Jokiniemi, J.

    2012-12-01

    During a hypothetical severe nuclear accident, the radiation field will be very high in the nuclear reactor containment building. As a result gaseous radiolysis products will be formed. Elemental iodine can react in the gaseous phase with ozone to form solid iodine oxide aerosol particles (iodine oxide). Within the AIAS (Adsorption of Iodine oxide Aerosols on Surfaces) project the interactions of iodine oxide (IOx) aerosols with common containment surface materials were investigated. Common surface materials in Swedish and Finnish LWRs are Teknopox Aqua V A paint films and metal surfaces such as Cu, Zn, Al and SS, as well as Pt and Pd surfaces from hydrogen recombiners. Non-radioactive and 131 I labelled iodine oxide aerosols were produced with the EXSI CONT facility from elemental iodine and ozone at VTT Technical Research Centre of Finland. The iodine oxide deposits were analysed with microscopic and spectroscopic measurement techniques to identify the kind of iodine oxide formed and if a chemical conversion on the different surface materials occurs. The revaporisation behaviour of the deposited iodine oxide aerosol particles from the different surface materials was studied under the influence of heat, humidity and gamma irradiation at Chalmers University of Technology, Sweden. Studies on the effects of humidity were performed using the FOMICAG facility, while heat and irradiation experiments were performed in a thermostated heating block and with a gammacell 22 having a dose rate of 14 kGy/h. The revaporisation losses were measured using a HPGe detector. The revaporisated 131 I species from the surfaces were chemically tested for elemental iodine formation. The parameter dominating the degradation of the produced iodine oxide aerosols was humidity. Cu and Zn surfaces were found to react with iodine from the iodine oxide aerosols to form iodides, while no metal iodides were detected for Al and SS samples. Most of the iodine oxide aerosols are assumed to be

  18. Study on thermo-oxide layers of uranium-niobium alloy

    International Nuclear Information System (INIS)

    Luo Lizhu; Yang Jiangrong; Zhou Ping

    2010-01-01

    Surface oxides structure of uranium-niobium alloys which were annealed under different temperatures (room temperature, 100, 200, 300 degree C, respectively)in air were studied by X-ray photoelectron spectroscopy (XPS) analysis and depth profile. Thickness of thermo-oxide layers enhance with the increasing oxide temperature, and obvious changes to oxides structure are observed. Under different delt temperatures, Nb 2 O 5 are detected on the initial surface of U-Nb alloys, and a layer of NbO mixed with some NbO x (0 2 O 5 and Nb metal. Dealing samples in air from room temperature to 200 degree C, non-stoichiometric UO 2+x (UO 2 + interstitial oxygen, P-type semiconductor) are found on initial surface of U-Nb alloys, which has 0.7 eV shift to lower binding energy of U 4f 7/2 characteristics comparing to that of UO 2 . Under room temperature, UO 2 are commonly detected in the oxides layer, while under temperature of 100 and 200 degree C, some P-type UO 2+x are found in the oxide layers,which has a satellite at binding energy of 396.6 eV. When annealing at 300 degree C, higher valence oxides, such as U 3 O 8 or UO x (2 5/2 and U 4f 7/2 peaks are 392.2 and 381.8 eV, respectively. UO 2 mixed uranium metal are the main compositions in the oxide layers. From the results, influence of temperature to oxidation of uranium is more visible than to niobium in uranium-niobium alloys. (authors)

  19. Ultrasonic-assisted synthesis and magnetic studies of iron oxide/MCM-41 nanocomposite

    International Nuclear Information System (INIS)

    Ursachi, Irina; Vasile, Aurelia; Ianculescu, Adelina; Vasile, Eugeniu; Stancu, Alexandru

    2011-01-01

    Highlights: → A quick and facile route for the synthesis of iron oxide/MCM-41 nanocomposite. → Magnetic nanoparticles were stabilized inside the pores of mesoporous silica MCM-41. → The pore size of MCM-41 dictates the properties of iron oxide nanoparticles. → The procedure provides a narrow size distribution of magnetic nanoparticles. - Abstract: Iron oxide nanoparticles were stabilized within the pores of mesoporous silica MCM-41 amino-functionalized by a sonochemical method. Formation of iron oxide nanoparticles inside the mesoporous channels of amino-functionalized MCM-41 was realized by wet impregnation using iron nitrate, followed by calcinations at 550 deg. C in air. The effect of functionalization level on structural and magnetic properties of obtained nanocomposites was studied. The resulting materials were characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy and selected area electron diffraction (HRTEM and SAED), vibrating sample and superconducting quantum interface magnetometers (VSM and SQUID) and nitrogen adsorption-desorption isotherms measurements. The HRTEM images reveal that the most of the iron oxide nanoparticles were dispersed inside the mesopores of silica matrix and the pore diameter of the amino-functionalized MCM-41 matrix dictates the particle size of iron oxide nanoparticles. The obtained material possesses mesoporous structure and interesting magnetic properties. Saturation magnetization value of magnetic iron oxide nanopatricles stabilized in MCM-41 amino-functionalized by in situ sonochemical synthesis was 1.84 emu g -1 . An important finding is that obtained magnetic nanocomposite materials exhibit enhanced magnetic properties than those of iron oxide/MCM-41 nanocomposite obtained by conventional method. The described method is providing a rather short preparation time and a narrow size distribution of iron oxide nanoparticles.

  20. Studies on nitric oxide removal in simulated gas compositions under plasma-dielectric/catalytic discharges

    International Nuclear Information System (INIS)

    Rajanikanth, B.S.; Rout, Satyabrata

    2001-01-01

    Application of pulsed electrical discharges for gas cleaning is gaining prominence, mainly from the energy consideration point of view. This present paper presents recent work on applying the electrical discharge plasma technology for treating gaseous pollutants, in general, and nitric oxide, in particular, as this is one of the major contributors to air pollution. The present work focuses attention on pulsed electrical discharge technique for nitric oxide removal from simulated gas compositions and study of effect of packed dielectric pellets, with and without a coating of catalyst, on the removal process. Experiments were conducted in a cylindrical corona reactor energized by repetitive high voltage pulses. The effects of various parameters, viz. pulse voltage magnitude, pulse frequency, initial nitric oxide concentration and gas mixture composition on nitric oxide removal efficiency, are discussed. When the reactors were filled with different dielectric pellets like, barium titanate, alumina, and alumina coated with palladium catalyst, the improvement in nitric oxide removal efficiency is studied and discussed. The power dissipated in the reactor and the energy consumed per nitric oxide molecule removed was calculated. Further results and comparative study of various cases are presented in the paper

  1. Advances of study on atmospheric methane oxidation (consumption) in forest soil

    Institute of Scientific and Technical Information of China (English)

    WANG Chen-rui; SHI Yi; YANG Xiao-ming; WU Jie; YUE Jin

    2003-01-01

    Next to CO2, methane (CH4) is the second important contributor to global warming in the atmosphere and global atmospheric CH4 budget depends on both CH4 sources and sinks. Unsaturated soil is known as a unique sink for atmospheric CH4 in terrestrial ecosystem. Many comparison studies proved that forest soil had the biggest capacity of oxidizing atmospheric CH4 in various unsaturated soils. However, up to now, there is not an overall review in the aspect of atmospheric CH4 oxidation (consumption) in forest soil. This paper analyzed advances of studies on the mechanism of atmospheric CH4 oxidation, and related natural factors (Soil physical and chemical characters, temperature and moisture, ambient main greenhouse gases concentrations, tree species, and forest fire) and anthropogenic factors (forest clear-cutting and thinning, fertilization, exogenous aluminum salts and atmospheric deposition, adding biocides, and switch of forest land use) in forest soils. It was believed that CH4 consumption rate by forest soil was limited by diffusion and sensitive to changes in water status and temperature of soil. CH4 oxidation was also particularly sensitive to soil C/N, Ambient CO2, CH4 and N2O concentrations, tree species and forest fire. In most cases, anthropogenic disturbances will decrease atmospheric CH4 oxidation, thus resulting in the elevating of atmospheric CH4. Finally, the author pointed out that our knowledge of atmospheric CH4 oxidation (consumption) in forest soil was insufficient. In order to evaluate the contribution of forest soils to atmospheric CH4 oxidation and the role of forest played in the process of global environmental change, and to forecast the trends of global warming exactly, more researchers need to studies further on CH4 oxidation in various forest soils of different areas.

  2. Synthesis, characterization and biological studies of copper oxide nanostructures

    Science.gov (United States)

    Jillani, Saquf; Jelani, Mohsan; Hassan, Najam Ul; Ahmad, Shahbaz; Hafeez, Muhammad

    2018-04-01

    The development of synthetic methods has been broadly accepted as an area of fundamental importance to the understanding and application of nanoscale materials. It allows the individual to modulate basic parameters such as morphology, particle size, size distributions, and composition. Several methods have been developed to synthesize CuO nanostructures with diverse morphologies, sizes, and dimensions using different chemical and physical based approaches. In this work, CuO nanostructures have been synthesized by aqueous precipitation method and simple chemical deposition method. The characterization of these products has been carried out by the x-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR) and UV–vis spectroscopy. Biological activity such as antibacterial nature of synthesized CuO is also explored. XRD peaks analysis revealed the monoclinic crystalline phase of copper oxide nanostructures. While the rod-like and particle-like morphologies have been observed in SEM results. FTIR spectra have confirmed the formation of CuO nanoparticles by exhibiting its characteristic peaks corresponding to 494 cm‑1 and 604 cm‑1. The energy band gap of the as-prepared CuO nanostructures determined from UV–vis spectra is found to be 2.18 eV and 2.0 eV for precipitation and chemically deposited samples respectively. The antibacterial activity results described that the synthesized CuO nanoparticles showed better activity against Staphylococcus aureus. The investigated results suggested the synthesis of highly stable CuO nanoparticles with significant antibacterial activities.

  3. In-situ oxidation study of Pd(100) by surface x-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Kilic, Volkan; Franz, Dirk; Stierle, Andreas [AG Grenzflaechen, Universitaet Siegen (Germany); Martin, Natalia; Lundgren, Edvin [Department of Synchrotron Radiation Research, Lund University (Sweden); Mantilla, Miguel [MPI fuer Metallforschung, Stuttgart (Germany)

    2011-07-01

    The oxidation of the Pd(100) surface at oxygen pressures in the 10{sup -6} mbar to 10{sup 3} mbar range and temperatures up to 1000 K has been studied in-situ by surface x-ray diffraction (SXRD). The SXRD experiments were performed at the MPI beamline at the Angstrom Quelle Karlsruhe (ANKA). We present the surface and crystal truncation rod (CTR) data from the ({radical}(5) x {radical}(5)) surface layer. We show that the transformation from the surface oxide to PdO bulk oxide can be observed in-situ under specific pressure and temperature conditions. We compare our results with previously proposed structure models based on low energy electron diffraction (LEED) I(V) curves and density functional theory calculations. Finally, we elucidate the question of commensurability of the surface oxide layer with respect to the Pd(100) substrate.

  4. Comparative study of oxidation in canned foods with a combination of vegetables and covering oils

    Directory of Open Access Journals (Sweden)

    E. Bravi

    2015-06-01

    Full Text Available The effects of sunflower (SFO, extra-virgin olive (EVO, and soybean oils (SBO, in combination with canned aubergins and dried tomatoes were studied during an accelerated shelf-life trial. Hydrolytic and oxidative quality parameters was determined and a sensorial test was run. For both canned vegetables, the SBO showed greater resistance to the oxidation at the end of the shelflife trial. The SBO in both vegetables yielded similar results for peroxide formation, whereas a reduced formation of secondary oxidation products was observed in aubergins. The results highlighted a higher oxidation stability of canned vegetables in SBO and EVO than those in SFO. The sensorial test underlined differences between the oils, in aubergins and dried tomatoes, after 30 days of accelerated storage (corresponding to the sell-by date. Flavour and texture were judged better for vegetables in SBO.

  5. Crystallographic and oxidation kinetic study of uranium dioxide by high temperature X-ray diffractometry

    International Nuclear Information System (INIS)

    Teixeira, S.R.

    1981-01-01

    The structural behavior of UO 2 sintered plates was studied as a function of temperature by X-ray diffractometry. All the experiments were carried out under an inert atmosphere with low oxygen content (approximated 140 ppm). The thermal expansion coefficient of UO 2 05 was found to be 10,5 x 10 - 6 0 C - 1 for temperatures above 165 0 C. Structural transformations during oxidation were observed at 170,235 and 275 0 C. The isothermal oxidation of UO 2 to U 3 O 7 follows a parabolic form and the diffusion of oxygen through the product layer U 4 O 9 is the mechanism controlling the oxidation rate. The phases observed were UO 2 (cubic) - U 4 O 9 (cubic) - U 3 O 7 (tetragonal). Activation energies of oxidation were found for different crystallographic planes (hkl). From this one can conclude that there is a preferential occupation of interstitial oxygen within the UO 2 structure. (Author) [pt

  6. Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR)

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Justine P. [Johns Hopkins Univ., Baltimore, MD (United States)

    2015-03-03

    Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR) Research during the project period focused primarily on mechanisms of water oxidation by structurally defined transition metal complexes. Competitive oxygen isotope fractionation of water, mediated by oxidized precursors or reduced catalysts together with ceric, Ce(IV), ammonium nitrate in aqueous media, afforded oxygen-18 kinetic isotope effects (O-18 KIEs). Measurement, calculation, and interpretation of O-18 KIEs, described in the accompanying report has important ramifications for the production of electricity and solar hydrogen (as fuel). The catalysis division of BES has acknowledged that understanding mechanisms of transition metal catalyzed water oxidation has major ramifications, potentially leading to transformation of the global economy and natural environment in years to come. Yet, because of program restructuring and decreased availability of funds, it was recommended that the Solar Photochemistry sub-division of BES would be a more appropriate parent program for support of continued research.

  7. Oxidization of squalene, a human skin lipid: a new and reliable marker of environmental pollution studies.

    Science.gov (United States)

    Pham, D-M; Boussouira, B; Moyal, D; Nguyen, Q L

    2015-08-01

    A review of the oxidization of squalene, a specific human compound produced by the sebaceous gland, is proposed. Such chemical transformation induces important consequences at various levels. Squalene by-products, mostly under peroxidized forms, lead to comedogenesis, contribute to the development of inflammatory acne and possibly modify the skin relief (wrinkling). Experimental conditions of oxidation and/or photo-oxidation mechanisms are exposed, suggesting that they could possibly be bio-markers of atmospheric pollution upon skin. Ozone, long UVA rays, cigarette smoke… are shown powerful oxidizing agents of squalene. Some in vitro, ex vivo and in vivo testings are proposed as examples, aiming at studying ingredients or products capable of boosting or counteracting such chemical changes that, globally, bring adverse effects to various cutaneous compartments. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  8. Biomarkers of oxidative stress and DNA damage in agricultural workers: A pilot study

    International Nuclear Information System (INIS)

    Muniz, Juan F.; McCauley, Linda; Scherer, J.; Lasarev, M.; Koshy, M.; Kow, Y.W.; Nazar-Stewart, Valle; Kisby, G.E.

    2008-01-01

    Oxidative stress and DNA damage have been proposed as mechanisms linking pesticide exposure to health effects such as cancer and neurological diseases. A study of pesticide applicators and farmworkers was conducted to examine the relationship between organophosphate pesticide exposure and biomarkers of oxidative stress and DNA damage. Urine samples were analyzed for OP metabolites and 8-hydroxy-2'-deoxyguanosine (8-OH-dG). Lymphocytes were analyzed for oxidative DNA repair activity and DNA damage (Comet assay), and serum was analyzed for lipid peroxides (i.e., malondialdehyde, MDA). Cellular damage in agricultural workers was validated using lymphocyte cell cultures. Urinary OP metabolites were significantly higher in farmworkers and applicators (p < 0.001) when compared to controls. 8-OH-dG levels were 8.5 times and 2.3 times higher in farmworkers or applicators (respectively) than in controls. Serum MDA levels were 4.9 times and 24 times higher in farmworkers or applicators (respectively) than in controls. DNA damage (Comet assay) and oxidative DNA repair were significantly greater in lymphocytes from applicators and farmworkers when compared with controls. Markers of oxidative stress (i.e., increased reactive oxygen species and reduced glutathione levels) and DNA damage were also observed in lymphocyte cell cultures treated with an OP. The findings from these in vivo and in vitro studies indicate that organophosphate pesticides induce oxidative stress and DNA damage in agricultural workers. These biomarkers may be useful for increasing our understanding of the link between pesticides and a number of health effects

  9. Exploring routes to tailor the physical and chemical properties of oxides via doping: an STM study

    International Nuclear Information System (INIS)

    Nilius, Niklas

    2015-01-01

    Doping opens fascinating possibilities for tailoring the electronic, optical, magnetic, and chemical properties of oxides. The dopants perturb the intrinsic behavior of the material by generating charge centers for electron transfer into adsorbates, by inducing new energy levels for electronic and optical excitations, and by altering the surface morphology and hence the adsorption and reactivity pattern. Despite a vivid scientific interest, knowledge on doped oxides is limited when compared to semiconductors, which reflects the higher complexity and the insulating nature of many oxides. In fact, atomic-scale studies, aiming at a mechanistic understanding of dopant-related processes, are still scarce.In this article, we review our scanning tunneling microscopy (STM) experiments on thin, crystalline oxide films with a defined doping level. We demonstrate how the impurities alter the surface morphology and produce cationic/anionic vacancies in order to keep the system charge neutral. We discuss how individual dopants can be visualized in the lattice, even if they reside in subsurface layers. By means of STM-conductance and x-ray photoelectron spectroscopy, we determine the electronic impact of dopants, including the energies of their eigen states and local band-bending effects in the host oxide. Electronic transitions between dopant-induced gap states give rise to new optical modes, as detected with STM luminescence spectroscopy. From a chemical perspective, dopants are introduced to improve the redox potential of oxide materials. Electron transfer from Mo-donors, for example, alters the growth behavior of gold and activates O 2 molecules on a wide-gap CaO surface. Such results demonstrate the enormous potential of doped oxides in heterogeneous catalysis. Our experiments address the issue of doping from a fundamental viewpoint, posing questions on the lattice position, charge state, and electron-transfer potential of the impurity ions. Whether doped oxides are

  10. Exploring routes to tailor the physical and chemical properties of oxides via doping: an STM study

    Science.gov (United States)

    Nilius, Niklas

    2015-08-01

    Doping opens fascinating possibilities for tailoring the electronic, optical, magnetic, and chemical properties of oxides. The dopants perturb the intrinsic behavior of the material by generating charge centers for electron transfer into adsorbates, by inducing new energy levels for electronic and optical excitations, and by altering the surface morphology and hence the adsorption and reactivity pattern. Despite a vivid scientific interest, knowledge on doped oxides is limited when compared to semiconductors, which reflects the higher complexity and the insulating nature of many oxides. In fact, atomic-scale studies, aiming at a mechanistic understanding of dopant-related processes, are still scarce. In this article, we review our scanning tunneling microscopy (STM) experiments on thin, crystalline oxide films with a defined doping level. We demonstrate how the impurities alter the surface morphology and produce cationic/anionic vacancies in order to keep the system charge neutral. We discuss how individual dopants can be visualized in the lattice, even if they reside in subsurface layers. By means of STM-conductance and x-ray photoelectron spectroscopy, we determine the electronic impact of dopants, including the energies of their eigen states and local band-bending effects in the host oxide. Electronic transitions between dopant-induced gap states give rise to new optical modes, as detected with STM luminescence spectroscopy. From a chemical perspective, dopants are introduced to improve the redox potential of oxide materials. Electron transfer from Mo-donors, for example, alters the growth behavior of gold and activates O2 molecules on a wide-gap CaO surface. Such results demonstrate the enormous potential of doped oxides in heterogeneous catalysis. Our experiments address the issue of doping from a fundamental viewpoint, posing questions on the lattice position, charge state, and electron-transfer potential of the impurity ions. Whether doped oxides are

  11. Comparative studies of MOS-gate/oxide-passivated AlGaAs/InGaAs pHEMTs by using ozone water oxidation technique

    International Nuclear Information System (INIS)

    Lee, Ching-Sung; Hung, Chun-Tse; Chou, Bo-Yi; Hsu, Wei-Chou; Liu, Han-Yin; Ho, Chiu-Sheng; Lai, Ying-Nan

    2012-01-01

    Al 0.22 Ga 0.78 As/In 0.24 Ga 0.76 As pseudomorphic high-electron-mobility transistors (pHEMTs) with metal-oxide-semiconductor (MOS)-gate structure or oxide passivation by using ozone water oxidation treatment have been comprehensively investigated. Annihilated surface states, enhanced gate insulating property and improved device gain have been achieved by the devised MOS-gate structure and oxide passivation. The present MOS-gated or oxide-passivated pHEMTs have demonstrated superior device performances, including superior breakdown, device gain, noise figure, high-frequency characteristics and power performance. Temperature-dependent device characteristics of the present designs at 300–450 K are also studied. (paper)

  12. Studies of Reduced Graphene Oxide and Graphite Oxide in the Aspect of Their Possible Application in Gas Sensors

    Science.gov (United States)

    Drewniak, Sabina; Muzyka, Roksana; Stolarczyk, Agnieszka; Pustelny, Tadeusz; Kotyczka-Morańska, Michalina; Setkiewicz, Maciej

    2016-01-01

    The paper presents the results of investigations on resistance structures based on graphite oxide (GRO) and graphene oxide (rGO). The subject matter of the investigations was thaw the sensitivity of the tested structures was affected by hydrogen, nitrogen dioxide and carbon dioxide. The experiments were performed at a temperature range from 30 °C to 150 °C in two carrier gases: nitrogen and synthetic air. The measurements were also aimed at characterization of the graphite oxide and graphene oxide. In our measurements we used (among others) techniques such as: Atomic Force Microscopy (AFM); Scanning Electron Microscopy (SEM); Raman Spectroscopy (RS); Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Microscopy (XPS). The data resulting from the characterizations of graphite oxide and graphene oxide have made it possible to interpret the obtained results from the point of view of physicochemical changes occurring in these structures. PMID:26784198

  13. Studies of Reduced Graphene Oxide and Graphite Oxide in the Aspect of Their Possible Application in Gas Sensors.

    Science.gov (United States)

    Drewniak, Sabina; Muzyka, Roksana; Stolarczyk, Agnieszka; Pustelny, Tadeusz; Kotyczka-Morańska, Michalina; Setkiewicz, Maciej

    2016-01-15

    The paper presents the results of investigations on resistance structures based on graphite oxide (GRO) and graphene oxide (rGO). The subject matter of the investigations was thaw the sensitivity of the tested structures was affected by hydrogen, nitrogen dioxide and carbon dioxide. The experiments were performed at a temperature range from 30 °C to 150 °C in two carrier gases: nitrogen and synthetic air. The measurements were also aimed at characterization of the graphite oxide and graphene oxide. In our measurements we used (among others) techniques such as: Atomic Force Microscopy (AFM); Scanning Electron Microscopy (SEM); Raman Spectroscopy (RS); Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Microscopy (XPS). The data resulting from the characterizations of graphite oxide and graphene oxide have made it possible to interpret the obtained results from the point of view of physicochemical changes occurring in these structures.

  14. A comparative study of silver-graphene oxide nanocomposites as a recyclable catalyst for the aerobic oxidation of benzyl alcohol: Support effect

    Energy Technology Data Exchange (ETDEWEB)

    Zahed, Bahareh; Hosseini-Monfared, Hassan, E-mail: monfared@znu.ac.ir

    2015-02-15

    Graphical abstract: - Highlights: • Characteristics of three different graphene oxide (GO) are studied as a support for Ag nanoparticles. • The required conditions for a best support are determined. • For the first time the silver nanoparticles decorated GO as catalyst for aerobic oxidation of benzyl alcohol and the effects of the degree of reduction of GO on AgNPs on GO are reported. - Abstract: Three different nanocomposites of silver and graphene oxide, namely silver nanoparticles (AgNPs) immobilized on reduced graphene oxide (AgNPs/rGO), partially reduced graphene oxide (AgNPs/GO) and thiolated partially reduced graphene oxide (AgNPs/GOSH), were synthesized in order to compare their properties. Characterizations were carried out by infrared and UV–Vis and Raman spectroscopy, ICP, X-ray diffraction, SEM and TEM, confirming both the targeted chemical modification and the composite formation. The nanocomposites were successfully employed in the aerobic oxidation of benzyl alcohol at atmospheric pressure. AgNPs/GOSH is stable and recyclable catalyst which showed the highest activity in the aerobic oxidation of benzyl alcohol in the presence of N-hydroxyphthalimide (NHPI) to give benzaldehyde with 58% selectivity in 24 h at 61% conversion. The favorite properties of AgNPs/GOSH are reasonably attributed to the stable and well distributed AgNPs over GOSH due to strong adhesion between AgNPs and GOSH.

  15. Teaching the Properties of Chromium's Oxidation States with a Case Study Method

    Science.gov (United States)

    Ozdilek, Zehra

    2015-01-01

    The purpose of this study was to investigate how a mixed-method case study affects pre-service science teachers' awareness of hexavalent chromium pollution and content knowledge about the properties of chromium's different oxidation states. The study was conducted in Turkey with 55 sophomores during the fall semester of 2013-2014. The students…

  16. Fundamental Studies of Butane Oxidation over Model-Supported Vanadium Oxide Catalysts: Molecular Structure-Reactivity Relationships

    NARCIS (Netherlands)

    Wachs, I.E.; Jehng, J.M.; Deo, G.; Weckhuysen, B.M.; Guliants, V.V.; Benziger, J.B.; Sundaresan, S.

    1997-01-01

    The oxidation of n-butane to maleic anhydride was investigated over a series of model-supported vanadia catalysts where the vanadia phase was present as a two-dimensional metal oxide overlayer on the different oxide supports (TiO2, ZrO2, CeO2, Nb2O5, Al2O3, and SiO2). No correlation was found

  17. Oxidation of methane on nanoparticulate Au/TiO2 at low temperature: A combined microreactor and DFT study

    DEFF Research Database (Denmark)

    Walther, Guido; Jones, Glenn; Jensen, Søren

    2009-01-01

    Herein we present results from experimental and theoretical studies concerning low temperature oxidation of CH4 over TiO2 supported Au nanoparticles. Our findings suggest that partial oxidation cannot be achieved under these conditions (1 bar, 30–250 °C). In order to understand this further, resu......-calculations investigating the thermodynamics of CH4 oxidation on a stepped Au(2 1 1) surface. Keywords: Gold; Titanium dioxide; Catalysis; Microreactor; Methane; Oxidation; Particle size...

  18. Palladium nanoparticles anchored on graphene nanosheets: Methanol, ethanol oxidation reactions and their kinetic studies

    International Nuclear Information System (INIS)

    Nagaraju, D.H.; Devaraj, S.; Balaya, P.

    2014-01-01

    Highlights: • Palladium nanoparticles decorated graphene is synthesized in a single step. • Electro-catalytic activity of Gra/Pd toward alcohol oxidation is evaluated. • 1:1 Gra/Pd exhibits good electro-catalytic activity and efficient electron transfer. - Abstract: Palladium nanoparticles decorated graphene (Gra/Pd nanocomposite) was synthesized by simultaneous chemical reduction of graphene oxide and palladium salt in a single step. The negatively charged graphene oxide (GO) facilitates uniform distribution of Pd 2+ ions onto its surface. The subsequent reduction by hydrazine hydrate provides well dispersed Pd nanoparticles decorated graphene. Different amount of Pd nanoparticles on graphene was synthesized by changing the volume to weight ratio of GO to PdCl 2 . X-ray diffraction studies showed FCC lattice of Pd with predominant (1 1 1) plane. SEM and TEM studies revealed that thin graphene nanosheets are decorated by Pd nanoparticles. Raman spectroscopic studies revealed the presence of graphene nanosheets. The electro-catalytic activity of Gra/Pd nanocomposites toward methanol and ethanol oxidation in alkaline medium was evaluated by cyclic voltammetric studies. 1:1 Gra/Pd nanocomposite exhibited good electro-catalytic activity and efficient electron transfer. The kinetics of electron transfer was studied using chronoamperometry. Improved electro-catalytic activity of 1:1 Gra/Pd nanocomposite toward alcohol oxidation makes it as a potential anode for the alcohol fuel cells

  19. Palladium nanoparticles anchored on graphene nanosheets: Methanol, ethanol oxidation reactions and their kinetic studies

    Energy Technology Data Exchange (ETDEWEB)

    Nagaraju, D.H., E-mail: dhnagu@gmail.com [Department of Mechanical Engineering, 117 576 (Singapore); Materials Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 (Saudi Arabia); Devaraj, S. [Department of Mechanical Engineering, 117 576 (Singapore); School of Chemical and Biotechnology, SASTRA University, Thanjavur, 613 401 (India); Balaya, P., E-mail: mpepb@nus.edu.sg [Department of Mechanical Engineering, 117 576 (Singapore); Engineering Science Program, National University of Singapore, 117 576 (Singapore)

    2014-12-15

    Highlights: • Palladium nanoparticles decorated graphene is synthesized in a single step. • Electro-catalytic activity of Gra/Pd toward alcohol oxidation is evaluated. • 1:1 Gra/Pd exhibits good electro-catalytic activity and efficient electron transfer. - Abstract: Palladium nanoparticles decorated graphene (Gra/Pd nanocomposite) was synthesized by simultaneous chemical reduction of graphene oxide and palladium salt in a single step. The negatively charged graphene oxide (GO) facilitates uniform distribution of Pd{sup 2+} ions onto its surface. The subsequent reduction by hydrazine hydrate provides well dispersed Pd nanoparticles decorated graphene. Different amount of Pd nanoparticles on graphene was synthesized by changing the volume to weight ratio of GO to PdCl{sub 2}. X-ray diffraction studies showed FCC lattice of Pd with predominant (1 1 1) plane. SEM and TEM studies revealed that thin graphene nanosheets are decorated by Pd nanoparticles. Raman spectroscopic studies revealed the presence of graphene nanosheets. The electro-catalytic activity of Gra/Pd nanocomposites toward methanol and ethanol oxidation in alkaline medium was evaluated by cyclic voltammetric studies. 1:1 Gra/Pd nanocomposite exhibited good electro-catalytic activity and efficient electron transfer. The kinetics of electron transfer was studied using chronoamperometry. Improved electro-catalytic activity of 1:1 Gra/Pd nanocomposite toward alcohol oxidation makes it as a potential anode for the alcohol fuel cells.

  20. High resolution medium energy ion scattering study of silicon oxidation and oxy nitridation

    International Nuclear Information System (INIS)

    Gusev, E.P.; Lu, H.C.; Garfunkel, E.; Gustafsson, T.

    1998-01-01

    Full text: Silicon oxide is likely to remain the material of choice for gate oxides in microelectronics for the foreseeable future. As device become ever smaller and faster, the thickness of these layers in commercial products is predicted to be less than 50 Angstroms in just a few years. An understanding of such devices will therefore likely to be based on microscopic concepts and should now be investigated by atomistic techniques. With medium energy ion scattering (MEIS) using an electrostatic energy analyzer, depth profiling of thin (<60 Angstroms) silicon oxide films on Si(100) with 3 - 5 Angstroms depth resolution in the near region has been done. The growth mechanism of thin oxide films on Si(100) has been studied, using sequential oxygen isotope exposures. It is found that the oxide films are stoichiometric to within approx. 10 Angstroms of the interface. It is also found that the oxidation reactions occur at the surface, in the transition region and at interface, with only the third region being included in the conventional (Deal-Grove) model for oxide formation. Nitrogen is sometimes added to gate oxides, as it has been found empirically that his improves some of the electrical properties. The role, location and even the amount of nitrogen that exists in such films are poorly understood, and represent interesting analytical challenges. MEIS data will be presented that address these questions, measured for a number of different processing conditions. We have recently demonstrated how to perform nitrogen nano-engineering in such ultrathin gate dielectrics, and these results will also be discussed

  1. Treadmill Exercise Attenuates Retinal Oxidative Stress in Naturally-Aged Mice: An Immunohistochemical Study

    Directory of Open Access Journals (Sweden)

    Chan-Sik Kim

    2015-09-01

    Full Text Available In the retina, a number of degenerative diseases, including glaucoma, diabetic retinopathy, and age-related macular degeneration, may occur as a result of aging. Oxidative damage is believed to contribute to the pathogenesis of aging as well as to age-related retinal disease. Although physiological exercise has been shown to reduce oxidative stress in rats and mice, it is not known whether it has a similar effect in retinal tissues. The aim of this study was to evaluate retinal oxidative stress in naturally-aged mice. In addition, we evaluated the effects of aerobic training on retinal oxidative stress by immunohistochemically evaluating oxidative stress markers. A group of twelve-week-old male mice were not exercised (young control. Two groups of twenty-two-month-old male mice were created: an old control group and a treadmill exercise group. The old control group mice were not exercised. The treadmill exercise group mice ran on a treadmill (5 to 12 m/min, 30 to 60 min/day, 3 days/week for 12 weeks. The retinal thickness and number of cells in the ganglion cell layer of the naturally-aged mice were reduced compared to those in the young control mice. However, treadmill exercise reversed these morphological changes in the retinas. We evaluated retinal expression of carboxymethyllysine (CML, 8-hydroxy-2′-deoxyguanosine (8-OHdG and nitrotyrosine. The retinas from the aged mice showed increased CML, 8-OHdG, and nitrotyrosine immunostaining intensities compared to young control mice. The exercise group exhibited significantly lower CML levels and nitro-oxidative stress than the old control group. These results suggest that regular exercise can reduce retinal oxidative stress and that physiological exercise may be distinctly advantageous in reducing retinal oxidative stress.

  2. Mechanistic and kinetic studies on the OH-initiated atmospheric oxidation of fluoranthene

    International Nuclear Information System (INIS)

    Dang, Juan; Shi, Xiangli; Zhang, Qingzhu; Hu, Jingtian; Chen, Jianmin; Wang, Wenxing

    2014-01-01

    The atmospheric oxidation of polycyclic aromatic hydrocarbons (PAHs) can generate toxic derivatives which contribute to the carcinogenic potential of particulate organic matter. In this work, the mechanism of the OH-initiated atmospheric oxidation of fluoranthene (Flu) was investigated by using high-accuracy molecular orbital calculations. All of the possible oxidation pathways were discussed, and the theoretical results were compared with the available experimental observation. The rate constants of the crucial elementary reactions were evaluated by the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. The main oxidation products are a range of ring-retaining and ring-opening chemicals containing fluoranthols, fluoranthones, fluoranthenequinones, nitro-fluoranthenes, dialdehydes and epoxides. The overall rate constant of the OH addition reaction is 1.72 × 10 −11 cm 3 molecule −1 s −1 at 298 K and 1 atm. The atmospheric lifetime of Flu determined by OH radicals is about 0.69 days. This work provides a comprehensive investigation of the OH-initiated oxidation of Flu and should help to clarify its atmospheric conversion. - Highlights: • We studied a comprehensive mechanism of OH-initiated oxidation of fluoranthene. • We reported the formation pathways of fluoranthone, fluoranthenequinone and epoxide. • The rate constants of the crucial elementary steps were evaluated

  3. Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence

    Directory of Open Access Journals (Sweden)

    Matthias Augustin

    2015-01-01

    Full Text Available Manganese oxides are one of the most important groups of materials in energy storage science. In order to fully leverage their application potential, precise control of their properties such as particle size, surface area and Mnx+ oxidation state is required. Here, Mn3O4 and Mn5O8 nanoparticles as well as mesoporous α-Mn2O3 particles were synthesized by calcination of Mn(II glycolate nanoparticles obtained through an economical route based on a polyol synthesis. The preparation of the different manganese oxides via one route facilitates assigning actual structure–property relationships. The oxidation process related to the different MnOx species was observed by in situ X-ray diffraction (XRD measurements showing time- and temperature-dependent phase transformations occurring during oxidation of the Mn(II glycolate precursor to α-Mn2O3 via Mn3O4 and Mn5O8 in O2 atmosphere. Detailed structural and morphological investigations using transmission electron microscopy (TEM and powder XRD revealed the dependence of the lattice constants and particle sizes of the MnOx species on the calcination temperature and the presence of an oxidizing or neutral atmosphere. Furthermore, to demonstrate the application potential of the synthesized MnOx species, we studied their catalytic activity for the oxygen reduction reaction in aprotic media. Linear sweep voltammetry revealed the best performance for the mesoporous α-Mn2O3 species.

  4. Financial strain is associated with increased oxidative stress levels: the Women's Health and Aging Studies.

    Science.gov (United States)

    Palta, Priya; Szanton, Sarah L; Semba, Richard D; Thorpe, Roland J; Varadhan, Ravi; Fried, Linda P

    2015-01-01

    Elevated oxidative stress levels may be one mechanism contributing to poor health outcomes. Financial strain and oxidative stress are each predictors of morbidity and mortality, but little research has investigated their relationship. Community-dwelling older adults (n = 728) from the Women's Health and Aging Studies I and II were included in this cross-sectional analysis. Financial strain was ascertained as an ordinal response to: "At the end of the month, do you have more than enough money left over, just enough, or not enough?" Oxidative stress was measured using serum protein carbonyl concentrations. Linear regression was used to quantify the relationship between financial strain and oxidative stress. Participants who reported high financial strain exhibited 13.4% higher protein carbonyl concentrations compared to individuals who reported low financial strain (p = 0.002). High financial strain may be associated with increased oxidative stress, suggesting that oxidative stress could mediate associations between financial strain and poor health. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Calcium incorporation in graphene oxide particles: A morphological, chemical, electrical, and thermal study

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Kelly L.S. [Instituto Nacional de Metrologia, Qualidade e Tecnologia, Av. Nossa Sra. das Graças, 50, 25250-020 Duque de Caxias (Brazil); Instituto de Química, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 149, 21941-909 Rio de Janeiro (Brazil); Curti, Raphael V.; Araujo, Joyce R.; Landi, Sandra M.; Ferreira, Erlon H.M.; Neves, Rodrigo S.; Kuznetsov, Alexei; Sena, Lidia A. [Instituto Nacional de Metrologia, Qualidade e Tecnologia, Av. Nossa Sra. das Graças, 50, 25250-020 Duque de Caxias (Brazil); Archanjo, Braulio S., E-mail: bsarchanjo@inmetro.gov.br [Instituto Nacional de Metrologia, Qualidade e Tecnologia, Av. Nossa Sra. das Graças, 50, 25250-020 Duque de Caxias (Brazil); Achete, Carlos A. [Instituto Nacional de Metrologia, Qualidade e Tecnologia, Av. Nossa Sra. das Graças, 50, 25250-020 Duque de Caxias (Brazil); Departamento de Engenharia Metalúrgica e de Materiais, Universidade Federal do Rio de Janeiro, 21941-972 Rio de Janeiro (Brazil)

    2016-07-01

    Surface chemical modification and functionalization are common strategies used to provide new properties or functionalities to a material or to enhance existing ones. In this work, graphene oxide prepared using Hummers' method has been chemically modified with calcium ions by immersion in a calcium carbonate solution. Transmission electron microscopy analyses showed that graphene oxide (GO) and calcium incorporated graphene oxide have a morphology similar to an ultra-thin membrane composed of overlapping sheets. X-ray diffraction and Fourier-infrared spectroscopy show that calcium carbonate residue was completely removed by hydrochloric acid washes. Energy dispersive X-ray spectroscopy mapping showed spatially homogeneous calcium in Ca-incorporated graphene oxide sample after HCl washing. This Ca is mainly ionic according to X-ray photoelectron spectroscopy, and its incorporation promoted a small reduction in the graphene oxide structure, corroborated also by four-point probe measurements. A thermal study shows a remarkable increase in the GO stability with the presence of Ca{sup 2+} ions. - Highlights: • Graphene oxide has been chemically modified with Ca ions by immersion in a CaCO{sub 3} solution. • GO–Ca has morphology similar to an ultra-thin membrane composed of overlapping sheets. • CaCO{sub 3} residue was completely removed by acid washes, leaving only ionic calcium. • EDS maps show that Ca incorporation is spatially homogeneous in GO structure. • Thermal analyses show a remarkable increase in GO stability after Ca incorporation.

  6. Building Composite Fe-Mn Oxide Flower-Like Nanostructures: A Detailed Magnetic Study

    KAUST Repository

    Zuddas, Efisio; Lentijo Mozo, Sergio; Casu, Alberto; Deiana, Davide; Falqui, Andrea

    2017-01-01

    Here we show that it’s possible to produce different magnetic core-multiple shells heterostructures from monodispersed iron oxide spherical magnetic seeds by finely controlling the amount of a manganese precursor and using in a smart and simple way a cation exchange synthetic approach. In particular, by increasing the amount of precursor we were able to produce nanostructures ranging from Fe3O4/Mn-ferrite core/single shell nanospheres to larger, flower-like Fe3O4/Mn-ferrite/Mn3O4 core-double shell nanoparticles. We first demonstrate how the formation of the initial thin manganese-ferrite shell determines a dramatic reduction of the superficial disorder in the starting iron oxide, bringing to nanomagnets with lower hardness. Then, the growth of the second and most external manganese oxide shell causes the magnetical hardening of the heterostructures, while its magnetic exchange coupling with the rest of the heterostructure can be antiferromagentic or ferromagnetic, depending on the strength of the applied external magnetic field. This response is similar to that of an iron oxide-manganese oxide core-shell system but differs from what observed in multiple-shell heterostructures. Finally, we report as the most external shell becomes magnetically irrelevant above the ferrimagnetic-paramagnetic transition of the manganese oxide and the resulting magnetic behavior of the flower-like structures is then studied in-depth.

  7. Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

    Directory of Open Access Journals (Sweden)

    Thomas König

    2011-01-01

    Full Text Available Surfaces of thin oxide films were investigated by means of a dual mode NC-AFM/STM. Apart from imaging the surface termination by NC-AFM with atomic resolution, point defects in magnesium oxide on Ag(001 and line defects in aluminum oxide on NiAl(110, respectively, were thoroughly studied. The contact potential was determined by Kelvin probe force microscopy (KPFM and the electronic structure by scanning tunneling spectroscopy (STS. On magnesium oxide, different color centers, i.e., F0, F+, F2+ and divacancies, have different effects on the contact potential. These differences enabled classification and unambiguous differentiation by KPFM. True atomic resolution shows the topography at line defects in aluminum oxide. At these domain boundaries, STS and KPFM verify F2+-like centers, which have been predicted by density functional theory calculations. Thus, by determining the contact potential and the electronic structure with a spatial resolution in the nanometer range, NC-AFM and STM can be successfully applied on thin oxide films beyond imaging the topography of the surface atoms.

  8. Calcium incorporation in graphene oxide particles: A morphological, chemical, electrical, and thermal study

    International Nuclear Information System (INIS)

    Castro, Kelly L.S.; Curti, Raphael V.; Araujo, Joyce R.; Landi, Sandra M.; Ferreira, Erlon H.M.; Neves, Rodrigo S.; Kuznetsov, Alexei; Sena, Lidia A.; Archanjo, Braulio S.; Achete, Carlos A.

    2016-01-01

    Surface chemical modification and functionalization are common strategies used to provide new properties or functionalities to a material or to enhance existing ones. In this work, graphene oxide prepared using Hummers' method has been chemically modified with calcium ions by immersion in a calcium carbonate solution. Transmission electron microscopy analyses showed that graphene oxide (GO) and calcium incorporated graphene oxide have a morphology similar to an ultra-thin membrane composed of overlapping sheets. X-ray diffraction and Fourier-infrared spectroscopy show that calcium carbonate residue was completely removed by hydrochloric acid washes. Energy dispersive X-ray spectroscopy mapping showed spatially homogeneous calcium in Ca-incorporated graphene oxide sample after HCl washing. This Ca is mainly ionic according to X-ray photoelectron spectroscopy, and its incorporation promoted a small reduction in the graphene oxide structure, corroborated also by four-point probe measurements. A thermal study shows a remarkable increase in the GO stability with the presence of Ca"2"+ ions. - Highlights: • Graphene oxide has been chemically modified with Ca ions by immersion in a CaCO_3 solution. • GO–Ca has morphology similar to an ultra-thin membrane composed of overlapping sheets. • CaCO_3 residue was completely removed by acid washes, leaving only ionic calcium. • EDS maps show that Ca incorporation is spatially homogeneous in GO structure. • Thermal analyses show a remarkable increase in GO stability after Ca incorporation.

  9. Mechanistic and kinetic studies on the OH-initiated atmospheric oxidation of fluoranthene

    Energy Technology Data Exchange (ETDEWEB)

    Dang, Juan; Shi, Xiangli; Zhang, Qingzhu, E-mail: zqz@sdu.edu.cn; Hu, Jingtian; Chen, Jianmin; Wang, Wenxing

    2014-08-15

    The atmospheric oxidation of polycyclic aromatic hydrocarbons (PAHs) can generate toxic derivatives which contribute to the carcinogenic potential of particulate organic matter. In this work, the mechanism of the OH-initiated atmospheric oxidation of fluoranthene (Flu) was investigated by using high-accuracy molecular orbital calculations. All of the possible oxidation pathways were discussed, and the theoretical results were compared with the available experimental observation. The rate constants of the crucial elementary reactions were evaluated by the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. The main oxidation products are a range of ring-retaining and ring-opening chemicals containing fluoranthols, fluoranthones, fluoranthenequinones, nitro-fluoranthenes, dialdehydes and epoxides. The overall rate constant of the OH addition reaction is 1.72 × 10{sup −11} cm{sup 3} molecule{sup −1} s{sup −1} at 298 K and 1 atm. The atmospheric lifetime of Flu determined by OH radicals is about 0.69 days. This work provides a comprehensive investigation of the OH-initiated oxidation of Flu and should help to clarify its atmospheric conversion. - Highlights: • We studied a comprehensive mechanism of OH-initiated oxidation of fluoranthene. • We reported the formation pathways of fluoranthone, fluoranthenequinone and epoxide. • The rate constants of the crucial elementary steps were evaluated.

  10. Total OH reactivity study from VOC photochemical oxidation in the SAPHIR chamber

    Science.gov (United States)

    Yu, Z.; Tillmann, R.; Hohaus, T.; Fuchs, H.; Novelli, A.; Wegener, R.; Kaminski, M.; Schmitt, S. H.; Wahner, A.; Kiendler-Scharr, A.

    2015-12-01

    It is well known that hydroxyl radicals (OH) act as a dominant reactive species in the degradation of VOCs in the atmosphere. In recent field studies, directly measured total OH reactivity often showed poor agreement with OH reactivity calculated from VOC measurements (e.g. Nölscher et al., 2013; Lu et al., 2012a). This "missing OH reactivity" is attributed to unaccounted biogenic VOC emissions and/or oxidation products. The comparison of total OH reactivity being directly measured and calculated from single component measurements of VOCs and their oxidation products gives us a further understanding on the source of unmeasured reactive species in the atmosphere. This allows also the determination of the magnitude of the contribution of primary VOC emissions and their oxidation products to the missing OH reactivity. A series of experiments was carried out in the atmosphere simulation chamber SAPHIR in Jülich, Germany, to explore in detail the photochemical degradation of VOCs (isoprene, ß-pinene, limonene, and D6-benzene) by OH. The total OH reactivity was determined from the measurement of VOCs and their oxidation products by a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS) with a GC/MS/FID system, and directly measured by a laser-induced fluorescence (LIF) at the same time. The comparison between these two total OH reactivity measurements showed an increase of missing OH reactivity in the presence of oxidation products of VOCs, indicating a strong contribution to missing OH reactivity from uncharacterized oxidation products.

  11. Study of the phase composition of nanostructures produced by the local anodic oxidation of titanium films

    International Nuclear Information System (INIS)

    Avilov, V. I.; Ageev, O. A.; Konoplev, B. G.; Smirnov, V. A.; Solodovnik, M. S.; Tsukanova, O. G.

    2016-01-01

    The results of experimental studies of the phase composition of oxide nanostructures formed by the local anodic oxidation of a titanium thin film are reported. The data of the phase analysis of titanium-oxide nanostructures are obtained by X-ray photoelectron spectroscopy in the ion profiling mode of measurements. It is established that the surface of titanium-oxide nanostructures 4.5 ± 0.2 nm in height possesses a binding energy of core levels characteristic of TiO_2 (458.4 eV). By analyzing the titanium-oxide nanostructures in depth by X-ray photoelectron spectroscopy, the formation of phases with binding energies of core levels characteristic of Ti_2O_3 (456.6 eV) and TiO (454.8 eV) is established. The results can be used in developing the technological processes of the formation of a future electronic-component base for nanoelectronics on the basis of titanium-oxide nanostructures and probe nanotechnologies.

  12. Study of the Radical Chain Mechanism of Hydrocarbon Oxidation for In Situ Combustion Process

    Directory of Open Access Journals (Sweden)

    Alexandra Ushakova

    2017-01-01

    Full Text Available Despite the abundance of in situ combustion models of oil oxidation, many of the effects are still beyond consideration. For example, until now, initial stages of oxidation were not considered from a position of radical chain process. This is a serious difficulty for the simulation of oil recovery process that involves air injection. To investigate the initial stages of oxidation, the paper considers the sequence of chemical reactions, including intermediate short-living compounds and radicals. We have attempted to correlate the main stages of the reaction with areas of heat release observed in the experiments. The system of differential equations based on the equations of oxidation reactions was solved. Time dependence of peroxides formation and start of heat release is analytically derived for the initial stages. We have considered the inhibition of initial oxidation stages by aromatic oil compounds and have studied the induction time in dependence on temperature. Chain ignition criteria for paraffins and crude oil in presence of core samples were obtained. The calculation results are compared with the stages of oxidation that arise by high-pressure differential scanning calorimetry. According to experimental observations we have determined which reactions are important for the process and which can be omitted or combined into one as insignificant.

  13. Building Composite Fe-Mn Oxide Flower-Like Nanostructures: A Detailed Magnetic Study

    KAUST Repository

    Zuddas, Efisio

    2017-07-21

    Here we show that it’s possible to produce different magnetic core-multiple shells heterostructures from monodispersed iron oxide spherical magnetic seeds by finely controlling the amount of a manganese precursor and using in a smart and simple way a cation exchange synthetic approach. In particular, by increasing the amount of precursor we were able to produce nanostructures ranging from Fe3O4/Mn-ferrite core/single shell nanospheres to larger, flower-like Fe3O4/Mn-ferrite/Mn3O4 core-double shell nanoparticles. We first demonstrate how the formation of the initial thin manganese-ferrite shell determines a dramatic reduction of the superficial disorder in the starting iron oxide, bringing to nanomagnets with lower hardness. Then, the growth of the second and most external manganese oxide shell causes the magnetical hardening of the heterostructures, while its magnetic exchange coupling with the rest of the heterostructure can be antiferromagentic or ferromagnetic, depending on the strength of the applied external magnetic field. This response is similar to that of an iron oxide-manganese oxide core-shell system but differs from what observed in multiple-shell heterostructures. Finally, we report as the most external shell becomes magnetically irrelevant above the ferrimagnetic-paramagnetic transition of the manganese oxide and the resulting magnetic behavior of the flower-like structures is then studied in-depth.

  14. Synthesis and characterization of porous metal oxides and desulfurization studies of sulfur containing compounds

    Science.gov (United States)

    Garces Trujillo, Hector Fabian

    This thesis contains two parts: 1) synthesis and characterization of porous metal oxides that include zinc oxide and a porous mixed-valent manganese oxide with an amorphous structure (AMO) 2) the desulfurization studies for the removal of sulfur compounds. Zinc oxide with different nano-scale morphologies may result in various porosities with different adsorption capabilities. A tunable shape microwave synthesis of ZnO nano-spheres in a co-solvent mixture is presented. The ZnO nano-sphere material is investigated as a desulfurizing sorbent in a fixed bed reactor in the temperature range 200 to 400 °C and compared with ZnO nanorods and platelet-like morphologies. Fresh and sulfided materials were characterized by X-ray diffraction (XRD), BET specific surface area, pore volume, scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (SEM/EDX), Raman spectroscopy, and thermogravimetric analysis (TGA). The tunable shape microwave synthesis of ZnO presents a high sulfur sorption capacity at temperatures as low as 200 °C which accounts for a three and four fold enhancement over the other preparations presented in this work, and reached 76 % of the theoretical sulfur capacity (TSC) at 300 °C. Another ZnO material with a bimodal micro- and mesopore size distribution investigated as a desulfurizing sorbent presents a sorption capacity that reaches 87% of the theoretical value for desulfurization at 400 °C at breakthrough time. A deactivation model that considers the activity of the solid reactant was used to fit the experimental data. Good agreement between the experimental breakthrough curves and the model predictions are obtained. Manganese oxides are a type of metal oxide materials commonly used in catalytic applications. Little is known about the adsorption capabilities for the removal of sulfur compounds. One of these manganese oxides; amorphous manganese oxide (AMO) is highly promising material for low temperature sorption processes. Amorphous

  15. Basic design study on plutonium electro-refining facility of oxide fuel pyroelectrochemical reprocessing

    International Nuclear Information System (INIS)

    Ogura, Kenji; Kondo, Naruhito; Kamoshida, Hiroshi; Omori, Takashi

    2001-02-01

    The test facility basic design, utility necessity and estimation cost of the Oxide Fuel Pyro-process for the use of Chemical Processing Facility (CPF) of JNC have been studied with the information of the previous year concept study and the additional conditions. Drastic down sizing design change or the building reconstruction is necessary to place the Oxide Fuel Pyro-process Facility in the laboratory ''C'', because it is not possible to reserve enough maintenance space and the weight of the facility is over the acceptable limit of the building. A further study such as facility down sizing, apparatus detail design and experiment detail process treatment has to be planned. (author)

  16. Daily home measurements of exhaled nitric oxide in asthmatic children during natural birch pollen exposure

    DEFF Research Database (Denmark)

    Vahlkvist, Signe; Sinding, Marianne; Skamstrup, Kirsten

    2006-01-01

    the feasibility, repeatability, accuracy, sensitivity, and biologic plausibility of new handheld equipment for FENO measurements. We studied day-to-day home measurements of FENO during the birch pollen season in children with allergy to birch pollen and a history of mild asthma and rhinoconjunctivitis during...... this season, as well as in nonatopic children. METHODS: Eleven children with mild asthma and allergy to birch pollen, performed daily home measurements of FENO for 6 weeks before and during the birch pollen season by using a handheld FENO monitor (NIOX MINO). Additionally, FENO (chemiluminescence equipment...... of FENO to a wider group of asthma clinics and even home measurements....

  17. Study of the Reactive-element Effect in Oxidation of Fe-cr Alloys Using Transverse Section Analytical Electron Microscopy

    Science.gov (United States)

    King, W. E.; Ethridge, E. C.

    1985-01-01

    The role of trace additions of reactive elements like Y, Ce, Th, or Hf to Cr bearing alloys was studied by applying a new developed technique of transverse section analytical electron microscopy. This reactive-element effect improves the high temperature oxidation resistance of alloys by strongly reducing the high temperature oxidation rate and enhancing the adhesion of the oxide scale, however, the mechanisms for this important effect remain largely unknown. It is indicated that the presence of yttrium affects the oxidation of Fe-Cr-Y alloys in at least two ways. The reactive element alters the growth mechanism of the oxide scale as evidenced by the marked influence of the reactive element on the oxide scale microstructure. The present results also suggest that reactive-element intermetallic compounds, which internally oxidize in the metal during oxidation, act as sinks for excess vacancies thus inhibiting vacancy condensation at the scale-metal interface and possibly enhancing scale adhesion.

  18. Optimization of a model of red blood cells for the study of anti-oxidant drugs, in terms of concentration of oxidant and phosphate buffer.

    Science.gov (United States)

    Bureau, A; Lahet, J-J; Lenfant, F; Bouyer, F; Petitjean, M; Chaillot, B; Freysz, M

    2005-08-01

    The aggression of erythrocytes by an oxidative stress induces hemolysis. This paper aims to valid a model of erythrocytes in terms of composition of the phosphate buffer solution and of concentration of a well-known oxidant, AAPH. Three compositions of phosphate buffer solution are mixed with three concentrations of oxidant. The influence of these two parameters on hemolysis is independently studied by a variance analysis and a Kruskal-Wallis test when ANOVA is not available. The hemolysis rate increases with time at fixed oxidant concentration, but is not influenced by the composition of the buffer solution. The highest hemolysis rate, 90%, was only measured within 2 h with the highest oxidant concentration. If we retain this concentration of oxidant, the lower concentration of the buffer can by eliminated by a significant less hemolysis and the highest concentration of the buffer can by chosen in regard of the better precision for a similar hemolysis compared to the mean buffer. We hope to study the effect of anti-oxidant agent with such a model of erythrocytes.

  19. Kinetic Studies on the Oxidation of Some para and meta-Substituted Cinnamic Acids by Pyridinium Bromochromate in the Presence of Oxalic Acid (A Co-oxidation Study

    Directory of Open Access Journals (Sweden)

    G. Vanangamudi

    2009-01-01

    Full Text Available The kinetics of oxidation of cinnamic acids by pyridinium bromochromate (PBC in the presence of oxalic acid has been studied in acetic acid-water (60:40% medium. The reaction shows unit order dependence each with respect to oxidant as well as oxalic acid [OX], the order with respect to [H+] and [CA] are fractional. The reaction is acid catalyzed and a low dielectric constant favours the reaction. Increase the ionic strength has no effect on the reaction rate. In the case of substituted cinnamic acids the order with respect to substrate vary depending upon the nature of the substituent present in the ring. In general, the electron withdrawing substituents retard the rate while the electron releasing substituents enhance the rate of reaction. From the kinetic data obtained the activation parameters have been computed and a suitable mechanism has been proposed.

  20. Electrochemical studies on nanometal oxide-activated carbon composite electrodes for aqueous supercapacitors

    Science.gov (United States)

    Ho, Mui Yen; Khiew, Poi Sim; Isa, Dino; Chiu, Wee Siong

    2014-11-01

    In present study, the electrochemical performance of eco-friendly and cost-effective titanium oxide (TiO2)-based and zinc oxide-based nanocomposite electrodes were studied in neutral aqueous Na2SO3 electrolyte, respectively. The electrochemical properties of these composite electrodes were studied using cyclic voltammetry (CV), galvanostatic charge-discharge (CD) and electrochemical impedance spectroscopy (EIS). The experimental results reveal that these two nanocomposite electrodes achieve the highest specific capacitance at fairly low oxide loading onto activated carbon (AC) electrodes, respectively. Considerable enhancement of the electrochemical properties of TiO2/AC and ZnO/AC nanocomposite electrodes is achieved via synergistic effects contributed from the nanostructured metal oxides and the high surface area mesoporous AC. Cations and anions from metal oxides and aqueous electrolyte such as Ti4+, Zn2+, Na+ and SO32- can occupy some pores within the high-surface-area AC electrodes, forming the electric double layer at the electrode-electrolyte interface. Additionally, both TiO2 and ZnO nanoparticles can provide favourable surface adsorption sites for SO32- anions which subsequently facilitate the faradaic processes for pseudocapacitive effect. These two systems provide the low cost material electrodes and the low environmental impact electrolyte which offer the increased charge storage without compromising charge storage kinetics.

  1. A spectroelectrochemical and chemical study on oxidation of hydroxycinnamic acids in aprotic medium

    Energy Technology Data Exchange (ETDEWEB)

    Petrucci, Rita [Dipartimento di Ingegneria Chimica M.M.P.M., Universita di Roma ' La Sapienza' , via del Castro Laurenziano 7, I-00161 Rome (Italy)]. E-mail: rita.petrucci@uniroma1.it; Astolfi, Paola [Dipartimento di Scienze dei Materiali e della Terra, Universita Politecnica delle Marche, via Brecce Bianche, I-60131 Ancona (Italy); Greci, Lucedio [Dipartimento di Scienze dei Materiali e della Terra, Universita Politecnica delle Marche, via Brecce Bianche, I-60131 Ancona (Italy); Firuzi, Omidreza [Dipartimento di Farmacologia delle Sostanze Naturali e Fisiologia Generale, Universita di Roma ' La Sapienza' , p.le Aldo Moro 5, I-00185 Rome (Italy); Saso, Luciano [Dipartimento di Farmacologia delle Sostanze Naturali e Fisiologia Generale, Universita di Roma ' La Sapienza' , p.le Aldo Moro 5, I-00185 Rome (Italy); Marrosu, Giancarlo [Dipartimento di Ingegneria Chimica M.M.P.M., Universita di Roma ' La Sapienza' , via del Castro Laurenziano 7, I-00161 Rome (Italy)

    2007-02-01

    Electrochemical and chemical oxidation of hydroxycinnamic acids (HCAs) was studied to investigate the mechanisms occurring in their antioxidant activities in a protons poor medium. Electrolyses and chemical reactions were followed on-line by monitoring the UV-spectral changes with time; final solutions were analysed by HPLC-MS. Anodic oxidation of mono- and di-HCAs, studied by cyclic voltammetry and controlled potential electrolyses, occurs via a reversible one-step two-electrons process, yielding the corresponding stable phenoxonium cation. A cyclization product was also proposed, as supported by ESR studies. Chemical oxidation with lead dioxide leads to different oxidation products according to the starting substrate. Di-HCAs like chlorogenic and rosmarinic acids and the ethyl ester of caffeic acid gave the corresponding neutral o-quinones, while mono-HCAs like cumaric, ferulic and sinapinic acids yielded the corresponding unstable neutral phenoxyl radical, as supported by the formation of dimerization products evidenced by HPLC-MS. In the case of caffeic acid, traces of the dimerization product suggest that the neutral phenoxyl radical may competitively undergo dimerization or decomposition of the neutral quinone. Chemical oxidation of HCAs was also followed by ESR spectroscopy: the di-HCAs radical anions were generated and detected, whereas among the mono-HCAs only the phenoxyl radical of the sinapinic acid was recorded.

  2. A study on microwave oxidation of landfill leachate—Contributions of microwave-specific effects

    International Nuclear Information System (INIS)

    Chou, Yu-Chieh; Lo, Shang-Lien; Kuo, Jeff; Yeh, Chih-Jung

    2013-01-01

    Highlights: ► pH has an insignificant effect on TOC removals and 550 W has a well performance. ► MOP has well removals of color, UV 254 , and TOC at 550 W/85 °C. ► TOC removals were higher at higher microwave setting (550 W vs. 128 W). ► The microwave-specific effects on TOC removal were usually synergistic in MOP. ► COD analyses showed persulfate decayed rapidly in either MOP or CHO treatment. -- Abstract: Microwave oxidation process (MOP) was evaluated for treatment of landfill leachate. The experimental parameters include pH, temperature, oxidant doses, microwave power setting, and irradiation time. The study explored the microwave-specific effects of the MOP. The contributions of pure thermal, persulfate oxidation and microwave irradiation on TOC removal were quantified. It was then found the combinations of them were usually synergistic in MOP except two of them were antagonistic (128 W/85 °C/1 M Na 2 S 2 O 8 and 128 W/85 °C/2 M Na 2 S 2 O 8 ). At the highest temperature tested (85 °C) in this study, microwave irradiation may cause generation and termination of oxidizing radicals at adverse rates. The study also found that persulfate decayed rapidly in either MOP or conventional heating oxidation (CHO) treatment of landfill leachate

  3. Studies of high coverage oxidation of the Cu(100) surface using low energy positrons

    Science.gov (United States)

    Fazleev, N. G.; Maddox, W. B.; Weiss, A. H.

    2012-02-01

    The study of oxidation of single crystal metal surfaces is important in understanding the corrosive and catalytic processes associated with thin film metal oxides. The structures formed on oxidized transition metal surfaces vary from simple adlayers of chemisorbed oxygen to more complex structures which result from the diffusion of oxygen into subsurface regions. In this work we present the results of theoretical studies of positron surface and bulk states and annihilation probabilities of surface-trapped positrons with relevant core electrons at the oxidized Cu(100) surface under conditions of high oxygen coverage. Calculations are performed for various high coverage missing row structures ranging between 0.50 and 1.50 ML oxygen coverage. The results of calculations of positron binding energy, positron work function, and annihilation characteristics of surface trapped positrons with relevant core electrons as function of oxygen coverage are compared with experimental data obtained from studies of oxidation of the Cu(100) surface using positron annihilation induced Auger electron spectroscopy (PAES).

  4. A study of internal oxidation in carburized steels by glow discharge optical emission spectroscopy and scanning electron microscopy

    International Nuclear Information System (INIS)

    An, X; Cawley, J.; Rainforth, W.M.; Chen, L.

    2003-01-01

    The internal oxidation of Cr-Mn carburizing steel was studied. Internal oxidation was induced using a commercial carburizing process. Sputter erosion coupled with glow discharge optical emission spectroscopy (GDOES) was used to determine the depth profile elemental distribution within the internal oxidation layer (<10 μm). In addition, scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) studies were carried out on selected sputter eroded surfaces. Oxide type was identified primarily by transmission electron microscopy (TEM). The carburized surface was found to consist of a continuous oxide layer, followed by a complex internal oxidation layer, where Cr and Mn oxides were found to populate grain boundaries in a globular form in the near surface region. At greater depths (5-10 μm), Si oxides formed as a grain boundary network. The internal oxides (mainly complex oxides) grew quickly during the initial stages of the carburizing process (2 h, 800 deg. C+3 h, 930 deg. C). GDOES proved to be an excellent tool for the quantification of oxidation and element distribution as a function of depth, particularly when combined with SEM and TEM to identify oxide type and morphology

  5. Neuralgia do trigêmeo bilateral: relato de caso Neuralgia del trigémino bilateral: relato de caso Bilateral trigeminal neuralgia: case report

    Directory of Open Access Journals (Sweden)

    Caio Marcio Barros de Oliveira

    2009-08-01

    Full Text Available JUSTIFICATIVA E OBJETIVOS: A neuralgia do nervo trigêmeo é uma condição intensamente dolorosa, caracterizada por surtos de dor lancinante e súbita, tipo choque, com duração de poucos segundos a dois minutos e geralmente unilateral. Sua incidência anual é de cerca de 4,3 em 100.000 na população geral, tendo manifestação bilateral em apenas 3% desses casos. O objetivo deste artigo foi descrever um caso raro de neuralgia do trigêmeo primário bilateral. RELATO DO CASO: Paciente de 61 anos, maranhense, casada, do lar, com antecedente de hipertensão arterial e há seis anos com queixa de dor intensa em V2-V3 à esquerda, com duração de 5 a 10 segundos, em região lateral do nariz e mandibular, com piora ao falar, mastigar e com diminuição da temperatura. Já havia utilizado clorpromazina (3 mg a cada oito horas e carbamazepina (200 mg a cada oito horas durante seis meses sem alívio da dor. Ao exame físico apresentava alodinia térmica e mecânica em regiões de V2-V3. Estava em uso de gabapentina (1.200 mg ao dia com alívio parcial da dor. Foi então aumentada a gabapentina para 1500 mg ao dia e introduzida amitriptilina 12,5 mg à noite. Evoluiu com dor leve e esporádica com diminuição da intensidade da dor ao longo de 10 meses de tratamento, sendo reduzida progressivamente a gabapentina para 600 mg ao dia e mantida a amitriptilina 12,5 mg ao dia. Após um ano, começou a apresentar dor de característica semelhante em região mandibular à direita, tendo melhorado com aumento de gabapentina para 900 mg ao dia. Não apresentava exames alterados de tomografia ou ressonância magnética de encéfalo. CONCLUSÕES: A carbamazepina é o fármaco de primeira escolha para tratamento de neuralgia trigeminal, porém a gabapentina tem sido cada vez mais utilizada como primeira medida farmacológica ou em casos refratários à terapia convencional.JUSTIFICATIVA Y OBJETIVOS: La neuralgia del nervio trigémino es una condici

  6. Oxidative Damage to the Salivary Glands of Rats with Streptozotocin-Induced Diabetes-Temporal Study: Oxidative Stress and Diabetic Salivary Glands

    OpenAIRE

    Kna?, M.; Maciejczyk, M.; Daniszewska, I.; Klimiuk, A.; Matczuk, J.; Ko?odziej, U.; Waszkiel, D.; ?adny, J. R.; ?endzian-Piotrowska, M.; Zalewska, A.

    2016-01-01

    Objective. This study evaluated oxidative damage caused to the salivary glands in streptozotocin-induced diabetes (DM). Materials and Methods. Rats were divided into 4 groups: groups 1 and 2, control rats, and groups 3 and 4, DM rats. 8-Hydroxy-2′-deoxyguanosine (8-OHdG), protein carbonyl (PC), 4-hydroxynonenal protein adduct (4-HNE), oxidized and/or MDA-modified LDL-cholesterol (oxy-LDL/MDA), 8-isoprostanes (8-isoP), and oxidative stress index (OSI) were measured at 7 (groups 1 and 3) and 14...

  7. Deuterium oxide as a tool for the study of amino acid metabolism

    International Nuclear Information System (INIS)

    Mitra, R.; Burton, J.; Varner, J.E.

    1976-01-01

    We have used deuterium oxide in nontoxic concentrations to study, in intact seedlings, the biosynthesis of amino acids. The extent and pattern of deuteration, as determined by a gas--liquid chromatograph--mass spectrometer system, permits conclusions about the biosynthesis of individual amino acids and also about their exposure to transaminases and other enzymes that might introduce deuterium into specific positions of the amino acid by exchange. This method could be used to study amino acid biogenesis in any organism that can tolerate 20 to 40 percent deuterium oxide for a period of a few hours to a few days

  8. Radical-induced oxidation of RAFT agents : a kinetic study

    NARCIS (Netherlands)

    Li, Changxi; He, Junpo; Zhou, Yanwu; Gu, Yuankai; Yang, Yuliang

    2011-01-01

    Radical-induced oxidn. of reversible addn.-fragmentation chain transfer (RAFT) agents is studied with respect to the effect of mol. structure on oxidn. rate. The radicals are generated by homolysis of either azobisisobutyronitrile or alkoxyamine and transformed in situ immediately into peroxy

  9. Experimental and modeling study of the oxidation of n- and iso-butanal

    KAUST Repository

    Veloo, Peter S.; Dagaut, P.; Togbé , Casimir; Dayma, Guillaume; Sarathy, Mani; Westbrook, Charles K.; Egolfopoulos, Fokion N.

    2013-01-01

    Understanding the kinetics of large molecular weight aldehydes is essential in the context of both conventional and alternative fuels. For example, they are key intermediates formed during the low-temperature oxidation of hydrocarbons as well as during the high-temperature oxidation of oxygenated fuels such as alcohols. In this study, an experimental and kinetic modeling investigation of n-butanal (. n-butyraldehyde) and iso-butanal (. iso-butyraldehyde or 2-methylpropanal) oxidation kinetics was performed. Experiments were performed in a jet stirred reactor and in counterflow flames over a wide range of equivalence ratios, temperatures, and pressures. The jet stirred reactor was utilized to observe the evolution of stable intermediates and products for the oxidation of n- and iso-butanal at elevated pressures and low to intermediate temperatures. The counterflow configuration was utilized for the determination of laminar flame speeds. A detailed chemical kinetic interpretative model was developed and validated consisting of 244 species and 1198 reactions derived from a previous study of the oxidation of propanal (propionaldehyde). Extensive reaction pathway and sensitivity analysis was performed to provide detailed insight into the mechanisms governing low-, intermediate-, and high-temperature reactivity. The simulation results using the present model are in good agreement with the experimental laminar flame speeds and well within a factor of two of the speciation data obtained in the jet stirred reactor. © 2013 The Combustion Institute.

  10. Oxygen vacancies in oxides studied by annihilation of mono-energetic positrons

    Energy Technology Data Exchange (ETDEWEB)

    Hugenschmidt, Christoph; Pikart, Philip [ZWE FRM II, Technische Universitaet Muenchen, Lichtenbergstrasse 1, 85747 Garching (Germany); Physik-Department E21, Technische Universitaet Muenchen, James-Franck-Strasse, 85748 Garching (Germany); Schreckenbach, Klaus [Physik-Department E21, Technische Universitaet Muenchen, James-Franck-Strasse, 85748 Garching (Germany)

    2009-07-01

    Oxygen vacancies play a fundamental role for the material properties of various oxides, e.g. charge carrier density in high-Tc superconductors, magnetic properties of diluted magnetic semiconductors or paramagnetic properties of SiO{sub 2}. In this study, open volume defects in (metal) oxides are investigated by Doppler-broadening spectroscopy (DBS) of the positron annihilation. More detailed information about the chemical surrounding at the positron annihilation site is gained by additional coincident DBS experiments, where a signature of positrons annihilating with electrons from oxygen is observed. The mono-energetic positron beam at NEPOMUC was used which allows depth dependent measurements, and hence the investigation of thin oxide layers. Recent results for metallic oxides such as ZnO are presented and compared with various non-metallic oxides such as amorphous and crystalline SiO{sub 2}, oxygen terminated Si-surface, and ice. The role of neutral and charged oxygen vacancies and the application of the positron annihilation technique to study oxygen vacancies will be discussed.

  11. Study of the Stereochemistry and Oxidation Mechanism of Plant Polyphenols, Assisted by Computational Chemistry.

    Science.gov (United States)

    Matsuo, Yosuke

    2017-01-01

    In recent years, plant polyphenols have attracted great attention due to their wide range of biological activities. Certain kinds of polyphenols have complex structures; therefore, it is difficult to elucidate their total structure, including stereochemistry. In this study, we reinvestigated the stereostructures of two major C-glycosidic ellagitannins contained in Quercus plants, vescalagin and castalagin, and revised their stereostructures based on theoretical calculations of spectroscopic data. We also determined the structures of quercusnins A and B, isolated from the sapwood of Quercus crispula, based on theoretical calculations of NMR data. The oxidation mechanism of polyphenols has not been entirely elucidated. Therefore, we have also studied the oxidation mechanism of tea catechins during black tea production. Our investigation of the oxidation mechanism of black tea pigment theaflavins revealed that the difference in the position of the galloyl ester affords different oxidation products of theaflavins. In addition, oxidation products of pyrogallol-type catechins could be classified into three types-dehydrotheasinensins, theacitrins, and proepitheaflagallins; their detailed production and degradation mechanisms were also examined.

  12. Short overview on metabolomics approach to study pathophysiology of oxidative stress in cancer

    Directory of Open Access Journals (Sweden)

    Luka Andrisic

    2018-04-01

    Full Text Available Association of oxidative stress with carcinogenesis is well known, but not understood well, as is pathophysiology of oxidative stress generated during different types of anti-cancer treatments. Moreover, recent findings indicate that cancer associated lipid peroxidation might eventually help defending adjacent nonmalignant cells from cancer invasion. Therefore, untargeted metabolomics studies designed for advanced translational and clinical studies are needed to understand the existing paradoxes in oncology, including those related to controversial usage of antioxidants aiming to prevent or treat cancer. In this short review we have tried to put emphasis on the importance of pathophysiology of oxidative stress and lipid peroxidation in cancer development in relation to metabolic adaptation of particular types of cancer allowing us to conclude that adaptation to oxidative stress is one of the main driving forces of cancer pathophysiology. With the help of metabolomics many novel findings are being achieved thus encouraging further scientific breakthroughs. Combined with targeted qualitative and quantitative methods, especially immunochemistry, further research might reveal bio-signatures of individual patients and respective malignant diseases, leading to individualized treatment approach, according to the concepts of modern integrative medicine. Keywords: Carcinogenesis, Cancer, Oxidative stress, Lipid peroxidation, 4-hydroxynonenal, Glutathione, Metabolomics, Immunochemistry, Biomarkers, Omics science

  13. Experimental and modeling study of the oxidation of n- and iso-butanal

    KAUST Repository

    Veloo, Peter S.

    2013-09-01

    Understanding the kinetics of large molecular weight aldehydes is essential in the context of both conventional and alternative fuels. For example, they are key intermediates formed during the low-temperature oxidation of hydrocarbons as well as during the high-temperature oxidation of oxygenated fuels such as alcohols. In this study, an experimental and kinetic modeling investigation of n-butanal (. n-butyraldehyde) and iso-butanal (. iso-butyraldehyde or 2-methylpropanal) oxidation kinetics was performed. Experiments were performed in a jet stirred reactor and in counterflow flames over a wide range of equivalence ratios, temperatures, and pressures. The jet stirred reactor was utilized to observe the evolution of stable intermediates and products for the oxidation of n- and iso-butanal at elevated pressures and low to intermediate temperatures. The counterflow configuration was utilized for the determination of laminar flame speeds. A detailed chemical kinetic interpretative model was developed and validated consisting of 244 species and 1198 reactions derived from a previous study of the oxidation of propanal (propionaldehyde). Extensive reaction pathway and sensitivity analysis was performed to provide detailed insight into the mechanisms governing low-, intermediate-, and high-temperature reactivity. The simulation results using the present model are in good agreement with the experimental laminar flame speeds and well within a factor of two of the speciation data obtained in the jet stirred reactor. © 2013 The Combustion Institute.

  14. Oxidation Study of an Ultra High Temperature Ceramic Coatings Based on HfSiCN

    Science.gov (United States)

    Sacksteder, Dagny; Waters, Deborah L.; Zhu, Dongming

    2018-01-01

    High temperature fiber-reinforced ceramic matrix composites (CMCs) are important for aerospace applications because of their low density, high strength, and significantly higher-temperature capabilities compared to conventional metallic systems. The use of the SiCf/SiC and Cf/SiC CMCs allows the design of lighter-weight, more fuel efficient aircraft engines and also more advanced spacecraft airframe thermal protection systems. However, CMCs have to be protected with advanced environmental barrier coatings when they are incorporated into components for the harsh environments such as in aircraft engine or spacecraft applications. In this study, high temperature oxidation kinetics of an advanced HfSiCN coating on Cf/SiC CMC substrates were investigated at 1300 C, 1400 C, and 1500 C by using thermogravimetric analysis (TGA). The coating oxidation reaction parabolic rate constant and activation energy were estimated from the experimental results. The oxidation reaction studies showed that the coatings formed the most stable, predominant HfSiO4-HfO2 scales at 1400 C. A peroxidation test at 1400 C then followed by subsequent oxidation tests at various temperatures also showed more adherent scales and slower scale growth because of reduced the initial transient oxidation stage and increased HfSiO4-HfO2 content in the scales formed on the HfSiCN coatings.

  15. Structural, electronic, mechanical, and dynamical properties of graphene oxides: A first principles study

    International Nuclear Information System (INIS)

    Dabhi, Shweta D.; Gupta, Sanjay D.; Jha, Prafulla K.

    2014-01-01

    We report the results of a theoretical study on the structural, electronic, mechanical, and vibrational properties of some graphene oxide models (GDO, a-GMO, z-GMO, ep-GMO and mix-GMO) at ambient pressure. The calculations are based on the ab-initio plane-wave pseudo potential density functional theory, within the generalized gradient approximations for the exchange and correlation functional. The calculated values of lattice parameters, bulk modulus, and its first order pressure derivative are in good agreement with other reports. A linear response approach to the density functional theory is used to derive the phonon frequencies. We discuss the contribution of the phonons in the dynamical stability of graphene oxides and detailed analysis of zone centre phonon modes in all the above mentioned models. Our study demonstrates a wide range of energy gap available in the considered models of graphene oxide and hence the possibility of their use in nanodevices.

  16. Structural, electronic, mechanical, and dynamical properties of graphene oxides: A first principles study

    Energy Technology Data Exchange (ETDEWEB)

    Dabhi, Shweta D. [Department of Physics, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar 364001 (India); Gupta, Sanjay D. [V. B. Institute of Science, Department of Physics, C. U. Shah University, Wadhwan City - 363030, Surendranagar (India); Jha, Prafulla K., E-mail: prafullaj@yahoo.com [Department of Physics, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara-390002 (India)

    2014-05-28

    We report the results of a theoretical study on the structural, electronic, mechanical, and vibrational properties of some graphene oxide models (GDO, a-GMO, z-GMO, ep-GMO and mix-GMO) at ambient pressure. The calculations are based on the ab-initio plane-wave pseudo potential density functional theory, within the generalized gradient approximations for the exchange and correlation functional. The calculated values of lattice parameters, bulk modulus, and its first order pressure derivative are in good agreement with other reports. A linear response approach to the density functional theory is used to derive the phonon frequencies. We discuss the contribution of the phonons in the dynamical stability of graphene oxides and detailed analysis of zone centre phonon modes in all the above mentioned models. Our study demonstrates a wide range of energy gap available in the considered models of graphene oxide and hence the possibility of their use in nanodevices.

  17. The resolution of acyclic P-stereogenic phosphine oxides via the formation of diastereomeric complexes: A case study on ethyl-(2-methylphenyl)-phenylphosphine oxide.

    Science.gov (United States)

    Bagi, Péter; Varga, Bence; Szilágyi, András; Karaghiosoff, Konstantin; Czugler, Mátyás; Fogassy, Elemér; Keglevich, György

    2018-04-01

    As an example of acyclic P-chiral phosphine oxides, the resolution of ethyl-(2-methylphenyl)-phenylphosphine oxide was elaborated with TADDOL derivatives, or with calcium salts of the tartaric acid derivatives. Besides the study on the resolving agents, several purification methods were developed in order to prepare enantiopure ethyl-(2-methylphenyl)-phenylphosphine oxide. It was found that the title phosphine oxide is a racemic crystal-forming compound, and the recrystallization of the enantiomeric mixtures could be used for the preparation of pure enantiomers. According to our best method, the (R)-ethyl-(2-methylphenyl)-phenylphosphine oxide could be obtained with an enantiomeric excess of 99% and in a yield of 47%. Complete racemization of the enantiomerically enriched phosphine oxide could be accomplished via the formation of a chlorophosphonium salt. Characterization of the crystal structures of the enantiopure phosphine oxide was complemented with that of the diastereomeric intermediate. X-ray analysis revealed the main nonbonding interactions responsible for enantiomeric recognition. © 2018 Wiley Periodicals, Inc.

  18. Oxidation flow reactors (OFRs): overview of recent field and modeling studies

    Science.gov (United States)

    Jimenez, Jose-Luis; Palm, Brett B.; Peng, Zhe; Hu, Weiwei; Ortega, Amber M.; Li, Rui; Campuzano-Jost, Pedro; Day, Douglas A.; Stark, Harald; Brune, William H.; de Gouw, Joost; Schroder, Jason

    2016-04-01

    Oxidation flow reactors (OFRs) are popular tools for studying SOA formation and aging in both laboratory and field experiments. In an OFR, the concentration of an oxidant (OH, O3, or NO3) can be increased, leading to hours-months of equivalent atmospheric oxidation during the several-minute OFR residence time. Using gas- and particle-phase measurements from several recent field campaigns, we demonstrate SOA formation after oxidation of ambient air in an OFR. Typically, more SOA formation is observed from nighttime air than daytime air. This indicates that the concentration of SOA-forming gases in ambient air is relatively higher at night. Measured ambient VOCs are not able to explain the magnitude of SOA formation in the OFR, suggesting that typically unmeasured S/IVOCs (possibly VOC oxidation products or direct emissions) play a substantial intermediary role in ambient SOA formation. We also present highlights from recent OFR oxidant chemistry modeling studies. HOx, Ox, and photolysis chemistry was modeled for two common OH production methods (utilizing 185+254 nm UV light, or 254 nm only). OH exposure (OHexp) can be estimated within a factor of ~2 using model-derived equations, and can be verified in situ using VOC decay measurements. OHexp is strongly dependent on external OH reactivity, which may cause significant OH suppression in some circumstances (e.g., lab/source studies with high precursor concentrations). UV light photolysis and reaction with oxygen atoms are typically not major reaction pathways. Modeling the fate of condensable low-volatility organic gases (LVOCs) formed in an OFR suggests that LVOC fate is dependent on particle condensational sink. E.g., for the range of particle condensational sink at a remote pine forest, anywhere from 20-80% of produced LVOCs were predicted to condense onto aerosols for an OHexp of ~1 day, with the remainder lost to OFR or sampling line walls. Similar to large chamber wall loss corrections, a correction is needed

  19. Adsorption and oxidation of SO2 by graphene oxides: A van der Waals density functional theory study

    International Nuclear Information System (INIS)

    Zhang, Huijuan; Cen, Wanglai; Liu, Jie; Guo, Jiaxiu; Yin, Huaqiang; Ning, Ping

    2015-01-01

    Highlights: • Hydroxyl group enhances the adsorption of SO 2 on graphene oxide surface. • Hydroxyl group cuts down the barrier for the oxidation of SO 2 through H-bonding interaction. • A charge transfer channel, from surface hydroxyl group to adsorbed SO 2 molecule, and then from the adsorbed SO 2 to epoxy group, is found to underlie the promotion effects on the oxidation of SO 2 . - Abstract: Carbon materials have been used for low temperature (20–150 °C) catalytic removal of SO 2 from the coal-burned flue gases for a long time, but the mechanism at atomic level is still controversial. Density functional theory was used to investigate the adsorption and oxidation of SO 2 on elaborated graphene oxides (GOs) to discover the insights. It is found that the hydroxyl groups on GO surface possess bi-functional effects: both enhancing the adsorption of SO 2 through H-bonding interaction and reducing the reaction barrier for its oxidation to SO 3 . The promotion of oxidation is related to a pre-activation of the surface epoxy group. Based on Bader population, charge difference and electron localization function analysis, a charge transfer channel is proposed to explain the pre-activation

  20. Adsorption and oxidation of SO{sub 2} by graphene oxides: A van der Waals density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Huijuan [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500 (China); Cen, Wanglai, E-mail: cenwanglai@scu.edu.cn [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); National Engineering Technology Research Center for Flue Gas Desulfurization, Chengdu 610065 (China); Liu, Jie [Department of Environment Engineering, Chengdu University of Information Technology, Chengdu 610025 (China); Guo, Jiaxiu [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); National Engineering Technology Research Center for Flue Gas Desulfurization, Chengdu 610065 (China); Yin, Huaqiang [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); National Engineering Technology Research Center for Flue Gas Desulfurization, Chengdu 610065 (China); Institute of New Energy and Low Carbon Technology, Sichuan University, Chengdu 610065 (China); Ning, Ping, E-mail: ningping58@sina.com [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500 (China)

    2015-01-01

    Highlights: • Hydroxyl group enhances the adsorption of SO{sub 2} on graphene oxide surface. • Hydroxyl group cuts down the barrier for the oxidation of SO{sub 2} through H-bonding interaction. • A charge transfer channel, from surface hydroxyl group to adsorbed SO{sub 2} molecule, and then from the adsorbed SO{sub 2} to epoxy group, is found to underlie the promotion effects on the oxidation of SO{sub 2}. - Abstract: Carbon materials have been used for low temperature (20–150 °C) catalytic removal of SO{sub 2} from the coal-burned flue gases for a long time, but the mechanism at atomic level is still controversial. Density functional theory was used to investigate the adsorption and oxidation of SO{sub 2} on elaborated graphene oxides (GOs) to discover the insights. It is found that the hydroxyl groups on GO surface possess bi-functional effects: both enhancing the adsorption of SO{sub 2} through H-bonding interaction and reducing the reaction barrier for its oxidation to SO{sub 3}. The promotion of oxidation is related to a pre-activation of the surface epoxy group. Based on Bader population, charge difference and electron localization function analysis, a charge transfer channel is proposed to explain the pre-activation.

  1. Mechanistic interaction study of thin oxide dielectric with conducting organic electrode

    International Nuclear Information System (INIS)

    Sharma, Himani; Sethi, Kanika; Raj, P. Markondeya; Gerhardt, R.A.; Tummala, Rao

    2012-01-01

    Highlights: ► Thin film-oxide dielectric-organic electrode interface studies for investigating the leakage mechanism. ► XPS to elucidate chemical-structural changes on dielectric oxide surface. ► Correlates structural characterization data with capacitor leakage current and impedance spectroscopy characteristics. - Abstract: This paper aims at understanding the interaction of intrinsic conducting polymer, PEDT, with ALD-deposited Al 2 O 3 and thermally oxidized Ta 2 O 5 dielectrics, and the underlying mechanisms for increase in leakage currents in PEDT-based capacitors. Conducting polymers offer several advantages as electrodes for high surface area capacitors because of their lower resistance, self-healing and enhanced conformality. However, capacitors with in situ polymerized PEDT show poor electrical properties that are attributed to the interfacial interaction between the organic electrode and the oxide dielectric. This study focuses on characterizing these interactions. A combination of compositional, structural and electrical characterization techniques was applied to polymer-solid-state-capacitor to understand the interfacial chemical behavior and dielectric property deterioration of alumina and tantalum-oxide films. XPS and impedance studies were employed to understand the stiochiometric and compositional changes that occur in the dielectric film on interaction with in situ deposited PEDT. Based on the observations from several complimentary techniques, it is concluded that tantalum-pentoxide has more resistance towards chemical interaction with in situ polymerized PEDT. The thermally oxidized Ta 2 O 5 -PEDT system showed leakage current of 280 nA μF −1 at 3 V with a breakdown voltage of 30 V. On the other hand, Al 2 O 3 -PEDT capacitor showed leakage current of 50 μA μF −1 and a breakdown voltage of 40 V. The study reports direct evidence for the mechanism of resistivity drop in alumina dielectric with in situ polymerized PEDT electrode.

  2. A SIMPLE FLUORESCENT LABELING METHOD FOR STUDIES OF PROTEIN OXIDATION, PROTEIN MODIFICATION, AND PROTEOLYSIS

    Science.gov (United States)

    Pickering, Andrew. M.; Davies, Kelvin. J. A.

    2014-01-01

    Proteins are sensitive to oxidation, and oxidized proteins are excellent substrates for degradation by proteolytic enzymes such as the Proteasome and the mitochondrial Lon protease. Protein labeling is required for studies of protein turnover. Unfortunately, most labeling techniques involve 3H or 14C methylation which is expensive, exposes researchers to radioactivity, generates large amounts of radioactive waste, and allows only single-point assays because samples require acid-precipitation. Alternative labeling methods, have largely proven unsuitable, either because the probe itself is modified by the oxidant(s) being studied, or because the alternative labeling techniques are too complex or too costly for routine use. What is needed is a simple, quick, and cheap labeling technique that uses a non-radioactive marker, that binds strongly to proteins, is resistant to oxidative modification, and emits a strong signal. We have devised a new reductive method for labeling free carboxyl groups of proteins with the small fluorophore 7-amino-4-methycoumarin (AMC). When bound to target proteins, AMC fluoresces very weakly but when AMC is released by proteinases, proteases, or peptidases, it fluoresces strongly. Thus, without acid-precipitation, the proteolysis of any target protein can be studied continuously, in multiwell plates. In direct comparisons, 3H-labeled proteins and AMC-labeled proteins exhibited essentially identical degradation patterns during incubation with trypsin, cell extracts, and purified proteasome. AMC-labeled proteins are well-suited to study increased proteolytic susceptibility following protein modification, since the AMC-protein bond is resistant to oxidizing agents such as hydrogen peroxide and peroxynitrite, and is stable over time and to extremes of pH, temperature (even boiling), freeze-thawing, mercaptoethanol, and methanol. PMID:21988844

  3. The Association Between Oxidative Stress and Depressive Symptom Scores in Elderly Population: A Repeated Panel Study

    Directory of Open Access Journals (Sweden)

    Changwoo Han

    2016-09-01

    Full Text Available Objectives Previous epidemiological studies about oxidative stress and depression are limited by hospital-based case-control design, single-time measurements of oxidative stress biomarkers, and the small number of study participants. Therefore, in this study, we analyzed the association between biomarker of oxidative stress and depressive symptom scores using repeatedly measured panel data from a community-dwelling elderly population. Methods From 2008 to 2010, a total of 478 elderly participants residing in Seoul, Korea, were evaluated three times. Participants underwent the Korean version of the Short Form Generic Depression Scale (SGDS-K test for screening depression, and urinary malondialdehyde (MDA levels were measured as an oxidative stress biomarker. We used a generalized estimating equation with a compound symmetry covariance structure to estimate the effects of oxidative stress on depressive symptom scores. Results A two-fold increase in urinary MDA concentration was significantly associated with a 33.88% (95% confidence interval [CI], 21.59% to 47.42% increase in total SGDS-K scores. In subgroup analyses by gender, a two-fold increase in urinary MDA concentration was significantly associated with increased SGDS-K scores in both men and women (men: 30.88%; 95% CI, 10.24% to 55.37%; women: 34.77%; 95% CI, 20.09% to 51.25%. In bivariate analysis after an SGDS-K score ≥8 was defined as depression, the third and the fourth urinary MDA quartiles showed a significantly increased odds ratio(OR of depression compared to the lowest urinary MDA quartile (third quartile OR, 6.51; 95% CI, 1.77 to 24.00; fourth quartile OR, 7.11; 95% CI, 1.99 to 25.42. Conclusions Our study suggests a significant association between oxidative stress and depressive symptoms in the elderly population.

  4. Comparative study of water chemistry and surface oxide composition on alloy 600 steam generator tubing

    International Nuclear Information System (INIS)

    Bjoernkvist, L.; Norring, K.; Nyborg, L.

    1993-01-01

    The Ringhals 3 steam generators experience secondary IGSCC on the tubes at support plate locations. Its sister unit Ringhals 4 is so far without IGSCC. Extensive work has been carried out in order to determine the local chemistry in crevices and the composition of deposits and oxide films on the tubes. Hot soaks of the SG:s at zero power has been performed and the water chemistry in occluded crevices of the SGs was predicted to be alkaline, pH 300degreesC = 10. In addition to eddy current testing, a large number of tubes have been pulled and destructively examined. These analysis include SEM/EDS characterization of TSP crevice deposits and Auger electron spectroscopy (AES) with depth profiling to reveal the composition of the tube OD oxide film. The AES analysis show an outer oxide rich in Fe 3 O 4 , mostly deposited. The actual Alloy 600 oxide is found below the magnetite and is 1-2 μm thick. The composition profile of the oxide exhibits a Cr-depletion relative to Ni in the outer part of the oxide, whereas an enrichment is found in depth. In order to correlate the water chemistry to the oxide composition profiles and deposits on pulled tubes, reference samples were prepared in an autoclave. The environments were chosen similar to the predicted Ringhals 3 and 4 crevice chemistry. Exposure both in an alkaline (pH 320degreesC∼ 9.9) and an acidic (pH 320degreesC ∼4.3) environment, containing sodium, chloride and sulphate, was studied. Some samples were also found on the Alloy 600 samples exposed to alkaline environment. Thus the prediction of alkaline chemistry was verified. The enrichment of chromium relative to nickel was shown to be potential and time dependent resulting in an increased Cr/Ni ratio at Cr-max with increasing potential and time

  5. Positron Annihilation Study of Radiation Defects in Zinc Oxide

    OpenAIRE

    Tomiyama, Noriyuki; Takenaka, Minoru; Kuramoto, Eiichi

    1992-01-01

    Positron annihilation studies have been carried out to clarify the radiation induced defects in ZnO single crystals. Vapor-grown ZnO crystals were irradiated at 77 K with 28 MeV electrons. Before irradiation as-grown specimens showed the mean positron lifetime in the range of 160-195 ps. Electron irradiation increased the mean positron lifetime up to 205-210 ps.This long-lifetime disappeared until 473 K during successive isochronal annealing steps. The radiation-induced coloration was anneale...

  6. HREM study of Bi-oxide based high Tc superconductors

    International Nuclear Information System (INIS)

    Hewat, E.A.

    1988-01-01

    A HREM study of the superstructure and structural defects in Bi 2-x Pb x Sr 2 CaCu 2 O 8 and Bi 2-x Pb x (SrCa) 2 CuO 6 (for x=0 and x=0.4) is presented. The superstructures are shown to involve waves of distortion along the b-axis. These waves are locked on to the lattice positions so that they have a local wave length of 4,5,6,7 or 8 times the basic unit cell. The superstructures are composed of roughly periodic combinations of these basic building blocks (waves). The lead doped superconductors show a less pronounced but more complicated superstructure along b where two distinct periodicities close to 4 and 7 times the basic unit cell predominate. In each of the compounds studied the superstructure, in the better ordered crystals, is shown to be commensurate with a unit cell between 5 and 23 times the basic unit cell. The superstructure in Bi 2-x Pb x Sr 2 CaCu 2 O 8 is orthorhombic where as the superstructure in Bi 2-x Pb x (SrCa) 2 CuO 6 is monoclinic. All these superconductors have a low ''twin'' density (ie density of 90 0 twist boundaries). They exhibit many dislocations and dislocation arrays associated with the weak bonding between BiO planes. They also form non-stoechiometric stacking faults with local changes in the c-axis spacing between layers

  7. Palladium nanoparticles anchored on graphene nanosheets: Methanol, ethanol oxidation reactions and their kinetic studies

    KAUST Repository

    Nagaraju, Doddahalli H.

    2014-12-01

    Palladium nanoparticles decorated graphene (Gra/Pd nanocomposite) was synthesized by simultaneous chemical reduction of graphene oxide and palladium salt in a single step. The negatively charged graphene oxide (GO) facilitates uniform distribution of Pd2+ ions onto its surface. The subsequent reduction by hydrazine hydrate provides well dispersed Pd nanoparticles decorated graphene. Different amount of Pd nanoparticles on graphene was synthesized by changing the volume to weight ratio of GO to PdCl2. X-ray diffraction studies showed FCC lattice of Pd with predominant (1 1 1) plane. SEM and TEM studies revealed that thin graphene nanosheets are decorated by Pd nanoparticles. Raman spectroscopic studies revealed the presence of graphene nanosheets. The electro-catalytic activity of Gra/Pd nanocomposites toward methanol and ethanol oxidation in alkaline medium was evaluated by cyclic voltammetric studies. 1:1 Gra/Pd nanocomposite exhibited good electro-catalytic activity and efficient electron transfer. The kinetics of electron transfer was studied using chronoamperometry. Improved electro-catalytic activity of 1:1 Gra/Pd nanocomposite toward alcohol oxidation makes it as a potential anode for the alcohol fuel cells. © 2014 Elsevier Ltd.

  8. Electrochemistry-High Resolution Mass Spectrometry to Study Oxidation Products of Trimethoprim

    Directory of Open Access Journals (Sweden)

    Marc-André Lecours

    2018-01-01

    Full Text Available The study of the fate of emerging organic contaminants (EOCs, especially the identification of transformation products, after water treatment or in the aquatic environment, is a topic of growing interest. In recent years, electrochemistry coupled to mass spectrometry has attracted a lot of attention as an alternative technique to investigate oxidation metabolites of organic compounds. The present study used different electrochemical approaches, such as cyclic voltammetry, electrolysis, electro-assisted Fenton reaction coupled offline to high resolution mass spectrometry and thin-layer flow cell coupled online to high resolution mass spectrometry, to study oxidation products of the anti-infective trimethoprim, a contaminant of emerging concern frequently reported in wastewaters and surface waters. Results showed that mono- and di-hydroxylated derivatives of trimethoprim were generated in electrochemically and possibly tri-hydroxylated derivatives as well. Those compounds have been previously reported as mammalian and bacterial metabolites as well as transformation products of advance oxidation processes applied to waters containing trimethoprim. Therefore, this study confirmed that electrochemical techniques are relevant not only to mimic specific biotransformation reactions of organic contaminants, as it has been suggested previously, but also to study the oxidation reactions of organic contaminants of interest in water treatment. The key role that redox reactions play in the environment make electrochemistry-high resolution mass spectrometry a sensitive and simple technique to improve our understanding of the fate of organic contaminants in the environment.

  9. 1H NMR and SPME-GC/MS study of hydrolysis, oxidation and other reactions occurring during in vitro digestion of non-oxidized and oxidized sunflower oil. Formation of hydroxy-octadecadienoates.

    Science.gov (United States)

    Nieva-Echevarría, Bárbara; Goicoechea, Encarnación; Manzanos, María J; Guillén, María D

    2017-01-01

    Both fresh and slightly oxidized sunflower oils, as models of omega-6 rich lipids, were submitted to in vitro gastrointestinal digestion and studied by 1 H NMR and SPME-GC/MS. Changes in lipolysis degree, lipid composition and oxidative level were studied by 1 H NMR. Three quantitative approaches were used and several equations were newly developed. In oxidized oil digestates slightly lower hydrolysis and a higher advance of oxidation took place during digestion. This latter was evidenced by a greater decrease of lipid unsaturation degree and enhanced generation of oxidation products (cis,trans-hydroperoxy-octadecadienoates, cis,trans- and trans,trans-hydroxy-octadecadienoates). For the first time, the generation of hydroxy-octadecadienoates during in vitro digestion is reported. Furthermore, SPME-GC/MS study of non-digested and digested samples headspaces confirmed that lipid oxidation occurred: abundances of volatile markers increased (including potentially toxic alpha,beta-unsaturated aldehydes), especially in oxidized oils digestates. Markers of Maillard-type and esterification reactions were also detected in the digestates. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Reliability study of ultra-thin gate oxides on strained-Si/SiGe MOS structures

    International Nuclear Information System (INIS)

    Varzgar, John B.; Kanoun, Mehdi; Uppal, Suresh; Chattopadhyay, Sanatan; Tsang, Yuk Lun; Escobedo-Cousins, Enrique; Olsen, Sarah H.; O'Neill, Anthony; Hellstroem, Per-Erik; Edholm, Jonas; Ostling, Mikael; Lyutovich, Klara; Oehme, Michael; Kasper, Erich

    2006-01-01

    The reliability of gate oxides on bulk Si and strained Si (s-Si) has been evaluated using constant voltage stressing (CVS) to investigate their breakdown characteristics. The s-Si architectures exhibit a shorter life time compared to that of bulk Si, which is attributed to higher bulk oxide charges (Q ox ) and increased surface roughness in the s-Si structures. The gate oxide in the s-Si structure exhibits a hard breakdown (HBD) at 1.9 x 10 4 s, whereas HBD is not observed in bulk Si up to a measurement period of 1.44 x 10 5 s. The shorter lifetime of the s-Si gate oxide is attributed to a larger injected charge (Q inj ) compared to Q inj in bulk Si. Current-voltage (I-V) measurements for bulk Si samples at different stress intervals show an increase in stress induced leakage current (SILC) of two orders in the low voltage regime from zero stress time to up to 5 x 10 4 s. In contrast, superior performance enhancements in terms of drain current, maximum transconductance and effective channel mobility are observed in s-Si MOSFET devices compared to bulk Si. The results from this study indicate that further improvement in gate oxide reliability is needed to exploit the sustained performance enhancement of s-Si devices over bulk Si

  11. Study the oxidation kinetics of uranium using XRD and Rietveld method

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yanzhi; Guan Weijun; Wang Qinguo; Wang Xiaolin; Lai Xinchun; Shuai Maobing, E-mail: yanzhizh@163.com [China Academy of Engineering Physics, PO Box 919-71, Mianyang, Sichuan, 621900 (China)

    2010-03-15

    The surface oxidation of uranium metal has been studied by X-ray diffraction (XRD) and Rietveld method in the range of 50{approx}300deg. C in air. The oxidation processes are analyzed by XRD to determine the extent of surface oxidation and the oxide structure. The dynamics expression for the formation of UO{sub 2} was derived. At the beginning, the dynamic expression was nonlinear, but switched to linear subsequently for uranium in air and humid oxygen. That is, the growth kinetics of UO{sub 2} can be divided into two stages: nonlinear portion and linear portion. Using the kinetic data of linear portion, the activation energy of reaction between uranium and air was calculated about 46.0 kJ/mol. However the content of oxide as a function of time was linear in humid helium ambience. Contrast the dynamics results, it prove that the absence of oxygen would accelerate the corrosion rate of uranium in the humid gas. We can find that the XRD and Rietveld method are a useful convenient method to estimate the kinetics and thermodynamics of solid-gas reaction.

  12. A CEMS study of surface oxidation of Fe-Ni alloys

    International Nuclear Information System (INIS)

    Cruz, B.; Tabares, J.A.; Bohorquez, A.; Perez Alcazar, G.A.

    1997-01-01

    A study by conversion electron Moessbauer spectroscopy (CEMS) carried out by using a parallel plate avalanche counter with samples of Fe-Ni alloys (50 and 65 at.% Fe) is reported. Each sample was analyzed without oxidation and after heating it under an oxygen atmosphere at 200 C. All CEMS measurements were carried out at room temperature. In both samples (50 and 65 at.% Fe), without oxidation and after oxidation, the Moessbauer spectra showed a six line magnetic spectrum according to their ferromagnetic character, with a broad hyperfine field distribution (HFD), according to the disordered character of the alloys. The obtained mean hyperfine field (MHF) for the sample 50 at.% Fe was 30.9 T, meanwhile for the invar composition (65 at.% Fe) was 25.5 T, which is close to values previously reported by transmission Moessbauer spectroscopy (TMS). Results from the treated samples (with oxidation at 200 C) showed a difference in the surface composition as a result of this process. In the 50 at.% Fe sample, additionally appeared a double that could be assigned to an oxihydroxide of Fe 3+ . Otherwise, the 65 at.% Fe sample (invar) presented ferromagnetic oxides (α-Fe 2 O 3 and Fe 3 O 4 ) with a large relative area (82.5%). (orig.)

  13. Near and mid infrared spectroscopy and multivariate data analysis in studies of oxidation of edible oils.

    Science.gov (United States)

    Wójcicki, Krzysztof; Khmelinskii, Igor; Sikorski, Marek; Sikorska, Ewa

    2015-11-15

    Infrared spectroscopic techniques and chemometric methods were used to study oxidation of olive, sunflower and rapeseed oils. Accelerated oxidative degradation of oils at 60°C was monitored using peroxide values and FT-MIR ATR and FT-NIR transmittance spectroscopy. Principal component analysis (PCA) facilitated visualization and interpretation of spectral changes occurring during oxidation. Multivariate curve resolution (MCR) method found three spectral components in the NIR and MIR spectral matrix, corresponding to the oxidation products, and saturated and unsaturated structures. Good quantitative relation was found between peroxide value and contribution of oxidation products evaluated using MCR--based on NIR (R(2) = 0.890), MIR (R(2) = 0.707) and combined NIR and MIR (R(2) = 0.747) data. Calibration models for prediction peroxide value established using partial least squares (PLS) regression were characterized for MIR (R(2) = 0.701, RPD = 1.7), NIR (R(2) = 0.970, RPD = 5.3), and combined NIR and MIR data (R(2) = 0.954, RPD = 3.1). Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Fenton-Like Oxidation of Malachite Green Solutions: Kinetic and Thermodynamic Study

    Directory of Open Access Journals (Sweden)

    Saeedeh Hashemian

    2013-01-01

    Full Text Available Oxidation by Fenton-like (Fe3+/H2O2 reactions is proven to be an economically feasible process for destruction of a variety of hazardous pollutants in wastewater. In this study, the degradation and mineralization of malachite green dye are reported using Fenton-like reaction. The effects of different parameters like pH of the solution, the initial concentrations of Fe3+, H2O2, and dye, temperature, and added electrolytes (Cl− and on the oxidation of the dye were investigated. Optimized condition was determined. The efficiency of 95.5% degradation of MAG after 15 minutes of reaction at pH 3 was obtained. TOC removal indicates partial and insignificant mineralization of malachite green dye. The results of experiments showed that degradation of malachite green dye in Fenton-like oxidation process can be described with a pseudo-second-order kinetic model. The thermodynamic constants of the Fenton oxidation process were evaluated. The results implied that the oxidation process was feasible, spontaneous, and endothermic. The results will be useful for designing the treatment systems of various dye-containing wastewaters.

  15. Study the oxidation kinetics of uranium using XRD and Rietveld method

    Science.gov (United States)

    Zhang, Yanzhi; Guan, Weijun; Wang, Qinguo; Wang, Xiaolin; Lai, Xinchun; Shuai, Maobing

    2010-03-01

    The surface oxidation of uranium metal has been studied by X-ray diffraction (XRD) and Rietveld method in the range of 50~300°C in air. The oxidation processes are analyzed by XRD to determine the extent of surface oxidation and the oxide structure. The dynamics expression for the formation of UO2 was derived. At the beginning, the dynamic expression was nonlinear, but switched to linear subsequently for uranium in air and humid oxygen. That is, the growth kinetics of UO2 can be divided into two stages: nonlinear portion and linear portion. Using the kinetic data of linear portion, the activation energy of reaction between uranium and air was calculated about 46.0 kJ/mol. However the content of oxide as a function of time was linear in humid helium ambience. Contrast the dynamics results, it prove that the absence of oxygen would accelerate the corrosion rate of uranium in the humid gas. We can find that the XRD and Rietveld method are a useful convenient method to estimate the kinetics and thermodynamics of solid-gas reaction.

  16. DFT study of cyanide oxidation on surface of Ge-embedded carbon nanotube

    Science.gov (United States)

    Gao, Wei; Milad Abrishamifar, Seyyed; Ebrahimzadeh Rajaei, Gholamreza; Razavi, Razieh; Najafi, Meysam

    2018-03-01

    In recent years, the discovery of suitable catalyst to oxidation of the cyanide (CN) has high importance in the industry. In present study, in the first step, the carbon nanotube (CNT) with the Ge atom embedded and the surface of Ge-CNT via the O2 molecule activated. In second step, the oxidation of CN on surface of the Ge-CNT via the Langmuir Hinshelwood (LH) and the Eley Rideal (ER) mechanisms was investigated. Results show that O2-Ge-CNT oxidized the CN molecule via the Ge-CNT-O-O∗ + CN → Ge-CNT-O-O∗-CN → Ge-CNT-O∗ + OCN and the Ge-CNT-O∗ + CN → Ge-CNT + OCN reactions. Results show that oxidation of CN on surface of Ge-CNT via the LH mechanism has lower energy barrier than ER mechanism. Finally, calculated parameters reveal that Ge-CNT is acceptable catalyst with high performance for CN oxidation, form theoretical point of view.

  17. Studies on room temperature electrochemical oxidation and its effect on the transport properties of TBCCO films

    International Nuclear Information System (INIS)

    Shirage, P M; Shivagan, D D; Pawar, S H

    2004-01-01

    A novel room temperature electrochemical process for the synthesis of single-phase Tl 2 Ba 2 Ca 2 Cu 3 O 10 (TBCCO/Tl-2223) superconducting films has been developed. Electrochemical parameters were optimized by studying linear sweep voltammetry (LSV), cyclic voltammetry (CV) and chronoamperometry (CA) for the deposition of Tl-Ba-Ca-Cu alloy at room temperature. The superconducting films of the TBCCO were obtained by two oxidation techniques. In the first technique, the electrodeposited Tl-Ba-Ca-Cu alloyed films were oxidized at various temperatures in flowing oxygen atmosphere. In the second technique, stoichiometric electrocrystallization to get Tl 2 Ba 2 Ca 2 Cu 3 O 10 (Tl-2223) was completed by electrochemically intercalating oxygen species into Tl-Ba-Ca-Cu alloy at room temperature for various lengths of time. The oxygen content in the samples was varied by varying the electrochemical oxidation period, and the changes in the crystal structure, superconducting transition temperature (T c ) and critical current density (J c ) were recorded. The high temperature furnace oxidation technique was replaced by the room temperature electrochemical oxidation technique. The dependence of superconducting parameters on oxygen content is correlated with structure-property relations

  18. Rhesus monkey lens as an in vitro model for studying oxidative stress

    International Nuclear Information System (INIS)

    Zigler, J.S. Jr.; Lucas, V.A.; Du, X.Y.

    1989-01-01

    Lenses from young rhesus monkeys were incubated in the presence of H 2 O 2 or oxygen radical generating systems to determine their suitability as a model for investigating lenticular oxidative stress. Additionally, direct comparisons were made between the effects found with the monkey lenses and those observed with cultured rat lenses exposed to the same oxidizing systems. As in earlier studies with rat lenses the monkey lenses exhibited impaired ability to actively accumulate from the medium radioactively labelled rubidium and choline following exposure to oxidative stress. Based on the effects of various scavengers of oxygen radicals it appeared that the mechanisms responsible for lens damage were the same for both rat and monkey lenses. However, rat lenses were damaged by lower concentrations of oxidants than were monkey lenses. It was concluded that oxidative stress affects both rat and monkey lenses by similar mechanisms but that lenses from monkeys, and probably other primates, are more resistant to these effects because they have better endogenous antioxidant defenses

  19. Detailed kinetic modeling study of n-pentanol oxidation

    KAUST Repository

    Heufer, Karl Alexander; Sarathy, Mani; Curran, Henry J.; Davis, Alexander C.; Westbrook, Charles K.; Pitz, William J.

    2012-01-01

    To help overcome the world's dependence upon fossil fuels, suitable biofuels are promising alternatives that can be used in the transportation sector. Recent research on internal combustion engines shows that short alcoholic fuels (e.g., ethanol or n-butanol) have reduced pollutant emissions and increased knock resistance compared to fossil fuels. Although higher molecular weight alcohols (e.g., n-pentanol and n-hexanol) exhibit higher reactivity that lowers their knock resistance, they are suitable for diesel engines or advanced engine concepts, such as homogeneous charge compression ignition (HCCI), where higher reactivity at lower temperatures is necessary for engine operation. The present study presents a detailed kinetic model for n-pentanol based on modeling rules previously presented for n-butanol. This approach was initially validated using quantum chemistry calculations to verify the most stable n-pentanol conformation and to obtain C-H and C-C bond dissociation energies. The proposed model has been validated against ignition delay time data, speciation data from a jet-stirred reactor, and laminar flame velocity measurements. Overall, the model shows good agreement with the experiments and permits a detailed discussion of the differences between alcohols and alkanes. © 2012 American Chemical Society.

  20. Structural and optical studies of Au doped titanium oxide films

    International Nuclear Information System (INIS)

    Alves, E.; Franco, N.; Barradas, N.P.; Nunes, B.; Lopes, J.; Cavaleiro, A.; Torrell, M.; Cunha, L.; Vaz, F.

    2012-01-01

    Thin films of TiO 2 were doped with Au by ion implantation and in situ during the deposition. The films were grown by reactive magnetron sputtering and deposited in silicon and glass substrates at a temperature around 150 °C. The undoped films were implanted with Au fluences in the range of 5 × 10 15 Au/cm 2 –1 × 10 17 Au/cm 2 with a energy of 150 keV. At a fluence of 5 × 10 16 Au/cm 2 the formation of Au nanoclusters in the films is observed during the implantation at room temperature. The clustering process starts to occur during the implantation where XRD estimates the presence of 3–5 nm precipitates. After annealing in a reducing atmosphere, the small precipitates coalesce into larger ones following an Ostwald ripening mechanism. In situ XRD studies reveal that Au atoms start to coalesce at 350 °C, reaching the precipitates dimensions larger than 40 nm at 600 °C. Annealing above 700 °C promotes drastic changes in the Au profile of in situ doped films with the formation of two Au rich regions at the interface and surface respectively. The optical properties reveal the presence of a broad band centered at 550 nm related to the plasmon resonance of gold particles visible in AFM maps.

  1. Structural and optical studies of Au doped titanium oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Alves, E., E-mail: ealves@itn.pt [Instituto Tecnologico e Nuclear (ITN), 2686-953 Sacavem (Portugal); Centro de Fisica Nuclear da Universidade de Lisboa, Av. Gama Pinto, 21649-003 Lisboa (Portugal); Franco, N.; Barradas, N.P. [Instituto Tecnologico e Nuclear (ITN), 2686-953 Sacavem (Portugal); Centro de Fisica Nuclear da Universidade de Lisboa, Av. Gama Pinto, 21649-003 Lisboa (Portugal); Nunes, B. [Instituto Tecnologico e Nuclear (ITN), 2686-953 Sacavem (Portugal); Lopes, J. [Instituto Superior de Engenharia de Lisboa (Portugal); Cavaleiro, A. [SEC-CEMUC - Universidade de Coimbra, Dept. Eng. Mecanica, Polo II, 3030-788 Coimbra (Portugal); Torrell, M.; Cunha, L.; Vaz, F. [Centro de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal)

    2012-02-01

    Thin films of TiO{sub 2} were doped with Au by ion implantation and in situ during the deposition. The films were grown by reactive magnetron sputtering and deposited in silicon and glass substrates at a temperature around 150 Degree-Sign C. The undoped films were implanted with Au fluences in the range of 5 Multiplication-Sign 10{sup 15} Au/cm{sup 2}-1 Multiplication-Sign 10{sup 17} Au/cm{sup 2} with a energy of 150 keV. At a fluence of 5 Multiplication-Sign 10{sup 16} Au/cm{sup 2} the formation of Au nanoclusters in the films is observed during the implantation at room temperature. The clustering process starts to occur during the implantation where XRD estimates the presence of 3-5 nm precipitates. After annealing in a reducing atmosphere, the small precipitates coalesce into larger ones following an Ostwald ripening mechanism. In situ XRD studies reveal that Au atoms start to coalesce at 350 Degree-Sign C, reaching the precipitates dimensions larger than 40 nm at 600 Degree-Sign C. Annealing above 700 Degree-Sign C promotes drastic changes in the Au profile of in situ doped films with the formation of two Au rich regions at the interface and surface respectively. The optical properties reveal the presence of a broad band centered at 550 nm related to the plasmon resonance of gold particles visible in AFM maps.

  2. Studying nature of oxide catalyst activity in olefine hydrogenetion

    International Nuclear Information System (INIS)

    Minachev, Kh.M.; Khodakov, Yu.S.; Makarov, P.A.

    1978-01-01

    La 2 O 3 activity nature in ethylene hydrogenation is discussed. The adsorbed forms of H 2 , ethylene, as well as CO, CO 2 , H 2 O, isolated at thermovacuum treatment, are studied. The conclusions on the mechanism of La 2 O 3 poizoning are made on the basis of investigation into interaction of C 2 H 4 and H 2 adsorbed forms with one another and with CO, CO 2 , H 2 O. It has been found that La 2 O 3 poisoning by water, CO and CO 2 at low-temperature ethylene hydrogenation is connected with the adsorptive hydrogen displacement. At adsorption temperatures of 20,-68,-78 deg, CO and CO 2 have been adsorbed in α-, β-, γ-forms; ethylene in α-and β-forms, and hydrogen only in the α-form. The adsorbed hydrogen at -68, -78 deg is irreversibly desorbed by CO and CO 2 . The adsorptive C 2 H 4 displacement by the above materials is observed only at 20 deg. According to the specific toxic effect of ethylene hydrogenation on La 2 O 3 poisons are placed in the following way: CO > CO 2 > H 2 O

  3. A comprehensive experimental and modeling study of isobutene oxidation

    KAUST Repository

    Zhou, Chong-Wen; Li, Yang; O'Connor, Eoin; Somers, Kieran P.; Thion, Sé bastien; Keesee, Charles; Mathieu, Olivier; Petersen, Eric L.; DeVerter, Trent A.; Oehlschlaeger, Matthew A.; Kukkadapu, Goutham; Sung, Chih-Jen; Alrefae, Majed; Khaled, Fathi; Farooq, Aamir; Dirrenberger, Patricia; Glaude, Pierre-Alexandre; Battin-Leclerc, Fré dé rique; Santner, Jeffrey; Ju, Yiguang; Held, Timothy; Haas, Francis M.; Dryer, Frederick L.; Curran, Henry J.

    2016-01-01

    The differences in low-temperature chemistry between alkanes and alkenes are also highlighted in this work. In normal alkanes, the fuel radical Ṙ adds to molecular oxygen forming alkylperoxyl (RȮ2) radicals followed by isomerization and chain branching reactions which promote low-temperature fuel reactivity. However, in alkenes, because of the relatively shallow well (∼20 kcal mol–1) for RȮ2 formation compared to ∼35 kcal mol–1 in alkanes, the Ṙ + O2 ⇌ RȮ2 equilibrium lies more to the left favoring Ṙ + O2 rather than RȮ2 radical stabilization. Based on this work, and related studies of allylic systems, it is apparent that reactivity for alkene components at very low temperatures (<800 K) emanates from hydroxyl radical addition followed by addition of molecular oxygen to radical. At intermediate temperatures (800–1300 K), alkene reactivity is controlled by hydrogen abstraction by molecular oxygen and the reactions between resonantly stabilized radicals and hydroperoxyl radicals which results in chain branching. At higher temperatures (>1300 K), the reactivity is mainly governed by the competition between hydrogen abstractions by molecular oxygen and ȮH radicals.

  4. Detailed kinetic modeling study of n-pentanol oxidation

    KAUST Repository

    Heufer, Karl Alexander

    2012-10-18

    To help overcome the world\\'s dependence upon fossil fuels, suitable biofuels are promising alternatives that can be used in the transportation sector. Recent research on internal combustion engines shows that short alcoholic fuels (e.g., ethanol or n-butanol) have reduced pollutant emissions and increased knock resistance compared to fossil fuels. Although higher molecular weight alcohols (e.g., n-pentanol and n-hexanol) exhibit higher reactivity that lowers their knock resistance, they are suitable for diesel engines or advanced engine concepts, such as homogeneous charge compression ignition (HCCI), where higher reactivity at lower temperatures is necessary for engine operation. The present study presents a detailed kinetic model for n-pentanol based on modeling rules previously presented for n-butanol. This approach was initially validated using quantum chemistry calculations to verify the most stable n-pentanol conformation and to obtain C-H and C-C bond dissociation energies. The proposed model has been validated against ignition delay time data, speciation data from a jet-stirred reactor, and laminar flame velocity measurements. Overall, the model shows good agreement with the experiments and permits a detailed discussion of the differences between alcohols and alkanes. © 2012 American Chemical Society.

  5. Adsorption and oxidation of SO2 by graphene oxides: A van der Waals density functional theory study

    Science.gov (United States)

    Zhang, Huijuan; Cen, Wanglai; Liu, Jie; Guo, Jiaxiu; Yin, Huaqiang; Ning, Ping

    2015-01-01

    Carbon materials have been used for low temperature (20-150 °C) catalytic removal of SO2 from the coal-burned flue gases for a long time, but the mechanism at atomic level is still controversial. Density functional theory was used to investigate the adsorption and oxidation of SO2 on elaborated graphene oxides (GOs) to discover the insights. It is found that the hydroxyl groups on GO surface possess bi-functional effects: both enhancing the adsorption of SO2 through H-bonding interaction and reducing the reaction barrier for its oxidation to SO3. The promotion of oxidation is related to a pre-activation of the surface epoxy group. Based on Bader population, charge difference and electron localization function analysis, a charge transfer channel is proposed to explain the pre-activation.

  6. Studies of surface states in zinc oxide nanopowders

    Science.gov (United States)

    Peters, Raul Mugabe

    The surface of ZnO semiconductor nanosystems is a key performance-defining factor in numerous applications. In this work we present experimental results for the surface defect-related properties of ZnO nanoscale systems. Surface photovoltage spectroscopy was used to determine the defect level energies within the band gap, the conduction vs. valence band nature of the defect-related transitions, and to probe key dynamic parameters of the surface on a number of commercially available ZnO nanopowders. In our experimental setup, surface photovoltage characterization is conducted in high vacuum in tandem with in situ oxygen remote plasma treatments. Surface photovoltage investigations of the as-received and plasma-processed samples revealed a number of common spectral features related to surface states. Furthermore, we observed significant plasma-induced changes in the surface defect properties. Ex situ positron annihilation and photoluminescence measurements were performed on the studied samples and correlated with surface photovoltage results. The average positron lifetimes were found to be substantially longer than in a bulk single crystalline sample, which is consistent with the model of grains with defect-rich surface and subsurface layers. Compression of the powders into pellets yielded reduction of the average positron lifetimes. Surface photovoltage, positron annihilation, and photoluminescence spectra consistently showed sample-to-sample differences due to the variation in the overall quality of the nanopowders, which partially obscures observation of the scaling effects. However, the results demonstrated that our approach is efficient in detecting specific surface states in nanoscale ZnO specimens and in elucidating their nature.

  7. Experimental and Kinetic Modeling Study of Methanol Ignition and Oxidation at High Pressure

    DEFF Research Database (Denmark)

    Aranda, V.; Christensen, J. M.; Alzueta, Maria

    2013-01-01

    A detailed chemical kinetic model for oxidation of CH3OH at high pressure and intermediate temperatures has been developed and validated experimentally. Ab initio calculations and Rice–Ramsperger–Kassel–Marcus/transition state theory (RRKM/TST) analysis were used to obtain rate coefficients for CH...... the conditions studied, the onset temperature for methanol oxidation was not dependent on the stoichiometry, whereas increasing pressure shifted the ignition temperature toward lower values. Model predictions of the present experimental results, as well as rapid compression machine data from the literature, were...

  8. Small-angle neutron scattering and cyclic voltammetry study on electrochemically oxidized and reduced pyrolytic carbon

    International Nuclear Information System (INIS)

    Braun, A.; Kohlbrecher, J.; Baertsch, M.; Schnyder, B.; Koetz, R.; Haas, O.; Wokaun, A.

    2004-01-01

    The electrochemical double layer capacitance and internal surface area of a pyrolytic carbon material after electrochemical oxidation and subsequent reduction was studied with cyclic voltammetry and small-angle neutron scattering. Oxidation yields an enhanced internal surface area (activation), and subsequent reduction causes a decrease of this internal surface area. The change of the Porod constant, as obtained from small-angle neutron scattering, reveals that the decrease in internal surface area is not caused merely by a closing or narrowing of the pores, but by a partial collapse of the pore network

  9. Surface adhesion properties of graphene and graphene oxide studied by colloid-probe atomic force microscopy

    International Nuclear Information System (INIS)

    Ding Yanhuai; Zhang Ping; Ren Huming; Zhuo Qin; Yang Zhongmei; Jiang Xu; Jiang Yong

    2011-01-01

    Surface adhesion properties are important to various applications of graphene-based materials. Atomic force microscopy is powerful to study the adhesion properties of samples by measuring the forces on the colloidal sphere tip as it approaches and retracts from the surface. In this paper we have measured the adhesion force between the colloid probe and the surface of graphene (graphene oxide) nanosheet. The results revealed that the adhesion force on graphene and graphene oxide surface were 66.3 and 170.6 nN, respectively. It was found the adhesion force was mainly determined by the water meniscus, which was related to the surface contact angle of samples.

  10. Sintering of oxide-supported Pt and Pd nanoparticles in air studied by in situ TEM

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose

    This thesis presents a fundamental study of the sintering of supported nanoparticles in relation to diesel oxidation catalysts. The sintering of supported nanoparticles is an important challenge in relation to this catalyst, as well as many other catalyst systems, and a fundamental understanding...... of Pt, Pd and bimetallic Pt-Pd nanoparticles supported on a flat and homogeneous Al2O3 or SiO2 surface. By using in situ TEM on the planar model catalysts it was possible to directly monitor the detailed dynamical changes of the individual nanoparticles during exposure to oxidizing conditions...

  11. Experimental study of nitrogen oxide absorption by a liquid nitrogen tetroxide flow

    International Nuclear Information System (INIS)

    Verzhinskaya, A.B.; Saskovets, V.V.; Borovik, T.F.

    1984-01-01

    The system of N 2 O 4 based coolant regeneration needs productive and efficient absorbers, providing effective production of nitrogen oxide, decreasing upon NPP operation at the expense of radiation-thermal decomposition. The experimental istallation flowsheet for studying the nitrogen oxide absorbtion by liquid nitrogen tetroxide is given. The experiments have been carried out in removable test sections, looked like helical tubes with internal steam-and-liquid mixture flow and external water cooling. Six test sections with variable geometry factors have been manufactured. The plotted results of the experiments are given as dependences of extraction level and mass transfer volumetric coefficients on the geometry factor, pressure and Froude number

  12. Preparation of Diatomite Supported Nano Zinc Oxide Composite Photocatalytic Material and Study on its Formaldehyde Degradation

    Science.gov (United States)

    Xiao, Liguang; Pang, Bo

    2017-09-01

    This experiment used zinc nitrate as precursor, ethanol as solvent and polyethylene glycol as dispersant, diatomite as carrier, diatomite loaded nano Zinc Oxide was prepared by sol-gel method, in addition, the formaldehyde degradation was studied by two kinds of experimental methods: preparation and loading, preparation and post loading, The samples were characterized by SEM, XRD, BET and IR. Experimental results showed that: Diatomite based nano Zinc Oxide had a continuous adsorption and degradation of formaldehyde, formaldehyde gas with initial concentration was 0.7mg/m3, after 36h degradation, the concentration reached 0.238mg/m3, the degradation rate reached to 66%.

  13. Theoretical aspects of studies of oxide and semiconductor surfaces using low energy positrons

    Science.gov (United States)

    Fazleev, N. G.; Maddox, W. B.; Weiss, A. H.

    2011-01-01

    This paper presents the results of a theoretical study of positron surface and bulk states and annihilation characteristics of surface trapped positrons at the oxidized Cu(100) single crystal and at both As- and Ga-rich reconstructed GaAs(100) surfaces. The variations in atomic structure and chemical composition of the topmost layers of the surfaces associated with oxidation and reconstructions and the charge redistribution at the surfaces are found to affect localization and spatial extent of the positron surface-state wave functions. The computed positron binding energy, work function, and annihilation characteristics reveal their sensitivity to charge transfer effects, atomic structure and chemical composition of the topmost layers of the surfaces. Theoretical positron annihilation probabilities with relevant core electrons computed for the oxidized Cu(100) surface and the As- and Ga-rich reconstructed GaAs(100) surfaces are compared with experimental ones estimated from the positron annihilation induced Auger peak intensities measured from these surfaces.

  14. Study of the processes of carbonization and oxidation of porous silicon by Raman and IR spectroscopy

    International Nuclear Information System (INIS)

    Vasin, A. V.; Okholin, P. N.; Verovsky, I. N.; Nazarov, A. N.; Lysenko, V. S.; Kholostov, K. I.; Bondarenko, V. P.; Ishikawa, Y.

    2011-01-01

    Porous silicon layers were produced by electrochemical etching of single-crystal silicon wafers with the resistivity 10 Ω cm in the aqueous-alcohol solution of hydrofluoric acid. Raman spectroscopy and infrared absorption spectroscopy are used to study the processes of interaction of porous silicon with undiluted acetylene at low temperatures and the processes of oxidation of carbonized porous silicon by water vapors. It is established that, even at the temperature 550°C, the silicon-carbon bonds are formed at the pore surface and the graphite-like carbon condensate emerges. It is shown that the carbon condensate inhibits oxidation of porous silicon by water vapors and contributes to quenching of white photoluminescence in the oxidized carbonized porous silicon nanocomposite layer.

  15. A preliminary study of ester oxidation on an aluminum surface using chemiluminescence

    Science.gov (United States)

    Jones, William R., Jr.; Meador, Michael A.; Morales, Wilfredo

    1987-01-01

    The oxidation characteristics of a pure ester (trimethyolpropane triheptanoate) were studied by using a chemiluminescence technique. Tests were run in a thin-film micro-oxidation apparatus with an aluminum alloy catalyst. Conditions included a pure oxygen atmosphere and a temperature range of 176 to 206 C. Results indicated that oxidation of the ester (containing 10 to the minus 3rd power M diphenylanthracene as an intensifier) was accompanied by emission of light. The maximum intensity of light emission (I sub max) was a function of the amount of ester, the concentration of intensifier, and the test temperature. The induction period or the time to reach one-half of maximum intensity (t sub 1/2) was an inverse function of test temperature. Decreases in light emission at the later stages of a test were caused by depletion of the intensifier.

  16. chemical kinetic study of nitrogen oxides formation in methane flameless combustion

    International Nuclear Information System (INIS)

    Alvarado T, Pedro N; Cadavid S, Francisco; Mondragon, P Fanor; Ruiz, Wilson

    2009-01-01

    The present paper deals with the nitrogen oxides formation in a flameless combustion process characterized for using air highly diluted and preheated at high temperatures. The combustion model used in this study was the one dimensional counterflow methane air diffusion flame. The NOx production rate analysis showed that the thermal and prompt mechanisms are the most important for the formation and consumption of NO under dilution conditions for the oxidant in N 2 and combustion products. These mechanisms are related since the starting reaction for NO formation (N2 molecular dissociation) belongs to the prompt mechanism while the NO formation is reported mainly for the thermal mechanism reactions. On the other hand, the NO - NO 2 equilibrium showed that the reaction rates are comparable to that obtained by the thermal and prompt mechanisms, but its global contribution to NO formation are almost insignificant due to the oxidation reaction with radicals HO 2 .

  17. Study of the electrocatalytic oxidation of Ethanol over platinum in medium acid

    International Nuclear Information System (INIS)

    Hoyos, Bibian; Gonzalez, Javier; Sanchez, Carlos

    2002-01-01

    Electro-catalytic oxidation of ethanol on platinum surfaces in sulfuric acid solutions at different temperatures and concentrations was studied by cyclic voltammetry. The results shown that there is ethanol adsorption at potentials below 0.4V (vs. RHE) with electrode coverage fraction for residues of 0.3 or less. There are also, two irreversible oxidation reactions. Former reaction seems be catalyzed by Pt(OH) species with electronic charge transfer control and the second reaction seems be catalyzed by Pt(OH) 4 with diffusion control while Pt(OH) 2 does not have catalytic activity. The activity and selectivity for total oxidation increases with ethanol concentration and temperature. Finally, a reaction mechanism, which explains the obtained data, is proposed

  18. First-Principles Study of Structure Property Relationships of Monolayer (Hydroxy)Oxide-Metal Bifunctional Electrocatalysts

    DEFF Research Database (Denmark)

    Zeng, Zhenhua; Kubal, Joseph; Greeley, Jeffrey Philip

    2015-01-01

    step towards accurate identification and prediction of a variety of oxide/electrode interfacial structure-properties relationships, but also provides the foundation for rational design and control of ‘targeted active phases’ at catalytic interfaces. The successful design of bifunctional......In the present study, on the basis of detailed density functional theory (DFT) calculations, and using Ni hydroxy(oxide) films on Pt(111) and Au(111) electrodes as model systems, we describe a detailed structural and electrocatalytic analysis of hydrogen evolution (HER) at three-phase boundaries...... under alkaline electrochemical conditions. We demonstrate that the structure and oxidation state of the films can be systematically tuned by changing the applied electrode potential and/or the nature of substrates. Structural features determined from the theoretical calculations provide a wealth...

  19. A kinetic study of the enhancement of solution chemiluminescence of glyoxylic acid oxidation by manganese species.

    Science.gov (United States)

    Otamonga, Jean-Paul; Abdel-Mageed, Amal; Agater, Irena B; Jewsbury, Roger A

    2015-08-01

    In order to study the mechanism of the enhancement of solution chemiluminescence, the kinetics of the decay of the oxidant and the chemiluminescence emission were followed for oxidations by permanganate, manganese dioxide sol and Mn(3+) (aq) of glyoxylic acid, using stopped-flow spectrophotometry. Results are reported for the glyoxylic acid oxidized under pseudo first-order conditions and in an acidic medium at 25 °C. For permanganate under these conditions, the decay is sigmoidal, consistent with autocatalysis, and for manganese dioxide sol and Mn(3+) it is pseudo first order. The effects of the presence of aqueous formaldehyde and Mn(2+) were observed and a fit to a simple mechanism is discussed. It is concluded that chemiluminescent enhancement in these systems is best explained by reaction kinetics. Copyright © 2014 John Wiley & Sons, Ltd.

  20. Experimental and Theoretical Studies on Corrosion Inhibition of Niobium and Tantalum Surfaces by Carboxylated Graphene Oxide

    Directory of Open Access Journals (Sweden)

    Valbonë Mehmeti

    2018-05-01

    Full Text Available The corrosion of two different metals, niobium and tantalum, in aqueous sulfuric acid solution has been studied in the presence and absence of carboxylated graphene oxide. Potentiodynamic measurements indicate that this nanomaterial inhibits corrosion due to its adsorption on the metal surfaces. The adsorbed layer of carboxylated graphene hinders two electrochemical reactions: the oxidation of the metal and the transport of metal ions from the metal to the solution but also hydrogen evolution reaction by acting as a protective barrier. The adsorption behavior at the molecular level of the carboxylated graphene oxide with respect to Nb, NbO, Ta, and TaO (111 surfaces is also investigated using Molecular Dynamic and Monte Carlo calculations.

  1. Nanoscopic morphological changes in yeast cell surfaces caused by oxidative stress: an atomic force microscopic study.

    Science.gov (United States)

    Canetta, Elisabetta; Walker, Graeme M; Adya, Ashok K

    2009-06-01

    Nanoscopic changes in the cell surface morphology of the yeasts Saccharomyces cerevisiae (strain NCYC 1681) and Schizosaccharomyces pombe (strain DVPB 1354), due to their exposure to varying concentrations of hydrogen peroxide (oxidative stress), were investigated using an atomic force microscope (AFM). Increasing hydrogen peroxide concentration led to a decrease in cell viabilities and mean cell volumes, and an increase in the surface roughness of the yeasts. In addition, AFM studies revealed that oxidative stress caused cell compression in both S. cerevisiae and Schiz. pombe cells and an increase in the number of aged yeasts. These results confirmed the importance and usefulness of AFM in investigating the morphology of stressed microbial cells at the nanoscale. The results also provided novel information on the relative oxidative stress tolerance of S. cerevisiae and Schiz. pombe.

  2. Experiments to study the erosive effect of oxide casting streams on structures

    International Nuclear Information System (INIS)

    Stuka, B.; Knauss, H.; Kammerer, B.; Perinic, D.

    1992-04-01

    The experiments performed under an activity of the Nuclear Safety Project (PSF) make a contribution to the study of the erosive effect of oxide casting streams on structures. As aluminothermically generated oxide casting stream, 20 mm in diameter, was applied from 1.0 m dropping height to 40 mm thick horizontal stainless steel plates in free air atmosphere. The test parameters were different temperatures of preheating of the plates (900 and 1200deg C). By means of thermocouples offset in depth in the plates it was possible to record and represent the temperature distribution in the plate correlated with time. Regarding the direct erosive effect of an oxide casting stream as a function of the temperature of plate preheating it appeared that a high initial temperature of the stainless steel plate (1200deg C) causes an increased erosion area at the surface only, but does not exert a macroscopically visible influence on erosion depth. (orig.) [de

  3. Study of cryoprotectors effect on oxidation processes at storage of frozen halffinished products

    Directory of Open Access Journals (Sweden)

    O. Glushkov

    2016-12-01

    Full Text Available The publication presents data on the effect of polysaccharides as cryoprotectants on changes of the lipid fraction of quick-frozen semi-finished products during storage. Since the structure of minced systems is formed as a result of the destruction of the native structure of the meat and the formation of a new secondary structure, it is important to establish the effect of cryoprotectants on the key functional and technological properties of meat systems after freezing, and in the process of storage. Based on studies of the kinetics of the oxidation of fat and accumulation data on the accumulation of the primary and secondary products of oxidation inhibition of oxidative processes has been found.

  4. Contribution to the study of the influence of porosity on carbon oxidation rate

    International Nuclear Information System (INIS)

    Serpinet, Joseph

    1956-01-01

    In its first part, this research thesis presents and described experiments of carbon oxidation which comprised the measurement of combustion rate in function of the BET surface of new types of graphite samples, and measurements of other kinetic quantities (reaction rate, Arrhenius activation energy, concentration of various gaseous oxides in reaction products). The second part reports a theoretical and experimental study of the possibility of limitation of the reaction rate, by using the slowness of oxygen diffusion within graphite pores. Results are related to the Thiele-Wheeler theory on chemical reactions in catalyst pores. The third part presents and discusses suggested solutions to replace this 'porosity hypothesis', and to explain why oxidation rate is almost never proportional to the BET surface all along the combustion process of a same graphite sample [fr

  5. Experimental study of the oxide film structural phase state in the E635 and E110 alloys

    International Nuclear Information System (INIS)

    Shevyakov, A. Yu.; Shishov, V. N.; Novikov, V. V.

    2013-01-01

    The microstructure, phase and element compositions of oxide films of E110 (Zr-1%Nb) and E635 (Zr-1%Nb-0,35%Fe-1,2%Sn) alloys after autoclave tests in pure water had been studied by the method of transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy (EDS). TEM investigations of oxide film structure were carried on different oxide layers according to their thickness (near interface of “metal-oxide”, in central part of the oxide film and near outer surface) and in cross-section. The results of the tests show that oxide films of the alloys have different microstructure (grain size, fraction of tetragonal phase, content of defects, etc) and the phase compositions. The crystal structure of oxide films is mainly monoclinic, however, at the “metal-oxide” interface there are a significant fraction of the tetragonal phase. Researching of oxides on different stages of oxidation allow us to determine the kinetics of the second phase precipitate structure change: a) in E635 alloy at early oxidation stages of the amorphization process of the Laves phase precipitates begins with decreasing the content of iron and niobium; b) in E110 alloy the amorphization process of β-Nb precipitates begins at a later stage of oxidation. The influence of changes of the crystal structure and the chemical composition of the second phase precipitates on protective properties of the oxides had been determined. Researching of alloying element redistribution in E635 alloy oxide film shows that iron and niobium are concentrated in pores. Increased porosity of the E635 alloy oxide films at a later oxidation stage, in comparison with the E110 alloy, shows the influence of change composition and subsequent dissolution of the Laves phase particles on the pore formation in the oxide. (authors)

  6. Cycle aging studies of lithium nickel manganese cobalt oxide-based batteries using electrochemical impedance spectroscopy

    NARCIS (Netherlands)

    Maheshwari, Arpit; Heck, Michael; Santarelli, Massimo

    2018-01-01

    The cycle aging of a commercial 18650 lithium-ion battery with graphite anode and lithium nickel manganese cobalt (NMC) oxide-based cathode at defined operating conditions is studied by regular electrochemical characterization, electrochemical impedance spectroscopy (EIS) and post-mortem analysis.

  7. Oxidation of clean silicon surfaces studied by four-point probe surface conductance measurements

    DEFF Research Database (Denmark)

    Petersen, Christian Leth; Grey, Francois; Aono, M.

    1997-01-01

    We have investigated how the conductance of Si(100)-(2 x 1) and Si(111)-(7 x 7) surfaces change during exposure to molecular oxygen. A monotonic decrease in conductance is seen as the (100) surfaces oxidizes. In contract to a prior study, we propose that this change is caused by a decrease in sur...

  8. Study of bismuth oxide compounds as cathodic materials in lithium accumulators

    International Nuclear Information System (INIS)

    Apostolova, R.D.; Shembel', E.M.

    1999-01-01

    Two groups of bismuth oxide base compounds: rare earth bismuthides - SmBiO 3 and EuBiO 3 , as well as the Aurivillius phase - Bi 4 V 2 O 11 , were synthesized and electrochemically studied as novel cathodic materials for high-energy lithium current sources [ru

  9. Dissolution and Protection of Aluminium Oxide in Corrosive Aqueous Media - An Ellipsometry and Reflectometry Study

    NARCIS (Netherlands)

    Karlsson, P.M.; Postmus, B.R.; Palmqvist, A.E.C.

    2009-01-01

    Dissolution of alumina has been studied from wafers in aqueous solution by means of ellipsometry and reflectometry. It was discovered that the dissolution of aluminium oxide is promoted by ethanol amines like N,N-bis(2-hydroxyethyl)glycine and triethanolamine, and that this dissolution is retarded

  10. Thermodynamic Performance Study of Biomass Gasification, Solid Oxide Fuel Cell and Micro Gas Turbine Hybrid Systems

    DEFF Research Database (Denmark)

    Bang-Møller, Christian; Rokni, Masoud

    2010-01-01

    A system level modelling study of three combined heat and power systems based on biomass gasification is presented. Product gas is converted in a micro gas turbine (MGT) in the first system, in a solid oxide fuel cell (SOFC) in the second system and in a combined SOFC–MGT arrangement in the third...

  11. Studying Impact of Different Precipitating Agents on Crystal Structure, Morphology and Photocatalytic Activity of Bismuth Oxide

    Directory of Open Access Journals (Sweden)

    Yayuk Astuti

    2017-10-01

    How to Cite: Astuti, Y., Arnelli, Pardoyo, Fauziyah, A., Nurhayati, S., Wulansari, A.D., Andianingrum, R., Widiyandari, H., Bhaduri, G.A. (2017. Studying Impact of Different Precipitating Agents on Crystal Structure, Morphology and Photocatalytic Activity of Bismuth Oxide. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (3: 478-484 (doi:10.9767/bcrec.12.3.1144.478-484

  12. Transmission Electron Microscopy Studies of Electron-Selective Titanium Oxide Contacts in Silicon Solar Cells

    KAUST Repository

    Ali, Haider; Yang, Xinbo; Weber, Klaus; Schoenfeld, Winston V.; Davis, Kristopher O.

    2017-01-01

    In this study, the cross-section of electron-selective titanium oxide (TiO2) contacts for n-type crystalline silicon solar cells were investigated by transmission electron microscopy. It was revealed that the excellent cell efficiency of 21

  13. Oxidative addition of aryl chlorides to monoligated palladium(0): A DFT-SCRF study

    DEFF Research Database (Denmark)

    Ahlquist, Mårten Sten Gösta; Norrby, Per-Ola

    2007-01-01

    Oxidative addition of aryl chlorides to palladium has been investigated by hybrid density functional theory methods (B3LYP), including a continuum model describing the solvent implicitly. A series of para-substituted aryl chlorides were studied to see the influence of electronic effects...

  14. Earthworms can increase nitrous oxide emissions from managed grassland: a field study

    NARCIS (Netherlands)

    Lubbers, I.M.; López González, E.; Hummelink, E.W.J.; Groenigen, van J.W.

    2013-01-01

    Earthworms are important in determining the greenhouse gas (GHG) balance of soils. In laboratory studies they have been shown to increase emissions of the potent GHG nitrous oxide (N2O). Here we test whether these earthworm-induced N2O emissions also occur in the field. We quantified N2O emissions

  15. Oxidation of L-cystine by chromium(VI) - a kinetic study | Kumar ...

    African Journals Online (AJOL)

    The kinetics of the title reaction was studied spectrophotometrically in HClO4 medium at 380 nm. The data suggested that the order with respect to cystine is fractional, whereas chromium(VI) follows first order kinetics. The reaction was second order in [H+]. Cysteic acid was found to be the main product of oxidation.

  16. Oxidant-antioxidant status in Egyptian children with sickle cell anemia: a single center based study

    Directory of Open Access Journals (Sweden)

    Mona Kamal El-Ghamrawy

    2014-05-01

    Conclusion: children with sickle cell anemia have chronic oxidative stress that may result inincreased VOC, and decreased serum nitrite may be associated with increases in VOC frequency. A novel finding in this study is the decrease in PON level in these patients, which is an interesting subject for further research.

  17. Methanol oxidation on stepped Pt[n(111) x (110)] electrodes: a chronoamperometric study

    NARCIS (Netherlands)

    Housmans, T.H.M.; Koper, M.T.M.

    2003-01-01

    The methanol oxidation reaction has been studied on Pt[n(111) × (110)]-type electrodes in a 0.5 M sulfuric acid and 0.025 M methanol solution, using cyclic voltammetry and chronoamperometry. The voltammetric behavior of methanol on the three electrodes under investigation [Pt(111), Pt(554), and

  18. Elevated oxidative stress among coronary artery disease patients on statin therapy: A cross sectional study

    Directory of Open Access Journals (Sweden)

    Sabitha Palazhy

    2015-05-01

    Conclusions: Though coronary artery disease subjects had healthy lipid profile, oxidative stress, a recognized risk factor for coronary events, was still elevated among this patient group. Novel risk factors were not found to be major predictors for coronary artery disease among the study subjects.

  19. Study of the emission oxidative reactions of ruthenium (II) complex by cationic compounds in anionic micelles

    International Nuclear Information System (INIS)

    Bonilha, J.B.S.

    1985-01-01

    The oxidative quenching of the emission of the tetraanionic complex tris (4,4' dicarboxylate - 2,2' - bipyridine ruthenium (II) in aqueous solution, by both organic and inorganic compounds in presence of anionic detergents, above and below the critical micelle concentration is studied. The organic cations, the inorganic ion and detergents used are shown. (M.J.C.) [pt

  20. Study of interaction of uranium, plutonium and rare earth fluorides with some metal oxides in fluoric salt melts

    International Nuclear Information System (INIS)

    Gorbunov, V.F.; Novoselov, G.P.; Ulanov, S.A.

    1976-01-01

    Interaction of plutonium, uranium, and rare-earth elements (REE) fluorides with aluminium and calcium oxides in melts of eutectic mixture LiF-NaF has been studied at 800 deg C by X-ray diffraction method. It has been shown that tetravalent uranium and plutonium are coprecipitated by oxides as a solid solution UO 2 -PuO 2 . Trivalent plutonium in fluorides melts in not precipitated in the presence of tetravalent uranium which can be used for their separation. REE are precipitated from a salt melt by calcium oxide and are not precipitated by aluminium oxide. Thus, aluminium oxide in a selective precipitator for uranium and plutonium in presence of REE. Addition of aluminium fluoride retains trivalent plutonium and REE in a salt melt in presence of Ca and Al oxides. The mechanism of interacting plutonium and REE trifluorides with metal oxides in fluoride melts has been considered