WorldWideScience

Sample records for oxide short defects

  1. Defects at oxide surfaces

    CERN Document Server

    Thornton, Geoff

    2015-01-01

    This book presents the basics and characterization of defects at oxide surfaces. It provides a state-of-the-art review of the field, containing information to the various types of surface defects, describes analytical methods to study defects, their chemical activity and the catalytic reactivity of oxides. Numerical simulations of defective structures complete the picture developed. Defects on planar surfaces form the focus of much of the book, although the investigation of powder samples also form an important part. The experimental study of planar surfaces opens the possibility of applying the large armoury of techniques that have been developed over the last half-century to study surfaces in ultra-high vacuum. This enables the acquisition of atomic level data under well-controlled conditions, providing a stringent test of theoretical methods. The latter can then be more reliably applied to systems such as nanoparticles for which accurate methods of characterization of structure and electronic properties ha...

  2. Defect Chemistry of Oxides for Energy Applications.

    Science.gov (United States)

    Schweke, Danielle; Mordehovitz, Yuval; Halabi, Mahdi; Shelly, Lee; Hayun, Shmuel

    2018-05-31

    Oxides are widely used for energy applications, as solid electrolytes in various solid oxide fuel cell devices or as catalysts (often associated with noble metal particles) for numerous reactions involving oxidation or reduction. Defects are the major factors governing the efficiency of a given oxide for the above applications. In this paper, the common defects in oxide systems and external factors influencing the defect concentration and distribution are presented, with special emphasis on ceria (CeO 2 ) based materials. It is shown that the behavior of a variety of oxide systems with respect to properties relevant for energy applications (conductivity and catalytic activity) can be rationalized by general considerations about the type and concentration of defects in the specific system. A new method based on transmission electron microscopy (TEM), recently reported by the authors for mapping space charge defects and measuring space charge potentials, is shown to be of potential importance for understanding conductivity mechanisms in oxides. The influence of defects on gas-surface reactions is exemplified on the interaction of CO 2 and H 2 O with ceria, by correlating between the defect distribution in the material and its adsorption capacity or splitting efficiency. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Creation of point defects in superconductors. A short review

    International Nuclear Information System (INIS)

    Quere, Yves; Rullier-Albenque, Florence.

    1981-11-01

    Many experiments have been published concerning the radiation damage in superconductors, but relatively few about the mechanisms of defect creation. A short review is presented of what is known on point defect creation in superconductors either by cold-work or by irradiation

  4. Regularities of radiation defects build up on oxide materials surface

    International Nuclear Information System (INIS)

    Bitenbaev, M.I.; Polyakov, A.I.; Tuseev, T.

    2005-01-01

    Analysis of experimental data by radiation defects study on different oxide elements (silicon, beryllium, aluminium, rare earth elements) irradiated by the photo-, gamma-, neutron-, alpha- radiation, protons and helium ions show, that gas adsorption process on the surface centers and radiation defects build up in metal oxide correlated between themselves. These processes were described by the equivalent kinetic equations for analysis of radiation defects build up in the different metal oxides. It was revealed in the result of the analysis: number of radiation defects are droningly increasing up to limit value with the treatment temperature growth. Constant of radicals death at ionizing radiation increases as well. Amount of surface defects in different oxides defining absorbing activity of these materials looks as: silicon oxide→beryllium oxide→aluminium oxide. So it was found, that most optimal material for absorbing system preparation is silicon oxide by it power intensity and berylium oxide by it adsorption efficiency

  5. Understanding the defect structure of solution grown zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Liew, Laura-Lynn [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, Block N4.1 Nanyang Avenue, Singapore 639798 (Singapore); Sankar, Gopinathan, E-mail: g.sankar@ucl.ac.uk [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Handoko, Albertus D. [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); Goh, Gregory K.L., E-mail: g-goh@imre.a-star.edu.sg [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, Block N4.1 Nanyang Avenue, Singapore 639798 (Singapore); Kohara, Shinji [Japan Synchrotron Radiation Research Institute (JASRI), Mikazuki, Sayo, Hyogo 679-5198 (Japan)

    2012-05-15

    Zinc oxide (ZnO) is a wide bandgap semiconducting oxide with many potential applications in various optoelectronic devices such as light emitting diodes (LEDs) and field effect transistors (FETs). Much effort has been made to understand the ZnO structure and its defects. However, one major issue in determining whether it is Zn or O deficiency that provides ZnO its unique properties remains. X-ray absorption spectroscopy (XAS) is an ideal, atom specific characterization technique that is able to probe defect structure in many materials, including ZnO. In this paper, comparative studies of bulk and aqueous solution grown ({<=}90 Degree-Sign C) ZnO powders using XAS and x-ray pair distribution function (XPDF) techniques are described. The XAS Zn-Zn correlation and XPDF results undoubtedly point out that the solution grown ZnO contains Zn deficiency, rather than the O deficiency that were commonly reported. This understanding of ZnO short range order and structure will be invaluable for further development of solid state lighting and other optoelectronic device applications. - Graphical abstract: Highlights: Black-Right-Pointing-Pointer ZnO powders have been synthesized through an aqueous solution method. Black-Right-Pointing-Pointer Defect structure studied using XAS and XPDF. Black-Right-Pointing-Pointer Zn-Zn correlations are less in the ZnO powders synthesized in solution than bulk. Black-Right-Pointing-Pointer Zn vacancies are present in the powders synthesized. Black-Right-Pointing-Pointer EXAFS and XPDF, when used complementary, are useful characterization techniques.

  6. Energetics and Defect Interactions of Complex Oxides for Energy Applications

    Science.gov (United States)

    Solomon, Jonathan Michael

    energetic stability for La solid solutions than for Y. Additionally, calculations performed for different atomic configurations show a preference for reduced (increased) oxygen vacancy coordination around La (Y) dopants. The current results are shown to be qualitatively consistent with related calculations and calorimetric measurements of heats of formation in other trivalent doped fluorite oxides, which show a tendency for increasing stability and increasing preference for higher oxygen coordination with increasing size of the trivalent impurity. We expand this investigation by considering a series of trivalent rare earth fission product cations, specifically, Y3+ (1.02 A, Shannon radius with eightfold coordination), Dy3+ (1.03 A), Gd 3+ (1.05 A), Eu3+ (1.07 A), Sm3+ (1.08 A), Pm3+ (1.09 A), Nd3+ (1.11 A), Pr3+ (1.13 A), Ce3+ (1.14 A) and La3+ (1.16 A). Compounds with ionic radius of the M3+ species smaller or larger than 1.09 A are found to have energetically preferred defect ordering arrangements. Systems with preferred defect ordering arrangements are suggestive of defect clustering in short range ordered solid solutions, which is expected to limit oxygen ion mobility and therefore the rate of oxidation of spent nuclear fuel. Finally, the energetics of rare earth substituted (M3+= La, Y, and Nd) UO2 solid solutions are investigated by employing a combination of calorimetric measurements and DFT based computations. The calorimetric studies are performed by Lei Zhang and Professor Alexandra Navrotsky at the University of Calfornia, Davis, as part of a joint computational/ experimental collaborative effort supported through the Materials Science of Actinides Energy Frontier Research Center. Calculated and measured formation enthalpies agree within 10 kJ/mol for stoichiometric oxygen/metal compositions. To better understand the factors governing the stability and defect binding in rare earth substituted urania solid solutions, systematic trends in the energetics are

  7. Short, medium and long term consequences of inadequate defect fuel management

    International Nuclear Information System (INIS)

    Roberts, J.G.; McQueen, M.; Nashiem, R.; Ma, G.

    2011-01-01

    Defect fuel pencils result in short, medium and long term consequences to the environment within and external to the nuclear power station. The paper will describe these consequences and specify the Defect Fuel Management Practices required to avoid these consequences.

  8. Short, medium and long term consequences of inadequate defect fuel management

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, J.G. [CANTECH Associates Ltd., Burlington, ON (Canada); McQueen, M.; Nashiem, R.; Ma, G. [Bruce Power, Tiverton, ON (Canada)

    2011-07-01

    Defect fuel pencils result in short, medium and long term consequences to the environment within and external to the nuclear power station. The paper will describe these consequences and specify the Defect Fuel Management Practices required to avoid these consequences.

  9. Complex defects in the oxidation of uranium

    International Nuclear Information System (INIS)

    MacCrone, R.K.; Sankaran, S.; Shatynski, S.R.; Colmenares, C.A.

    1986-01-01

    We are reporting EPR results obtained with uranium powder samples fully oxidized in dry air, water vapor, and air/water vapor mixtures. The results reported previously are confirmed and additional paramagnetic centers, associated with chemisorbed species, have been identified. The temperature dependence of the g-value for these centers from room temperature to 10K is also reported

  10. Defect driven tailoring of colossal dielectricity of Reduced Graphene Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, S.; Mondal, A. [Department of Physics, Jadavpur University, Kolkata 700 032 (India); Dey, K. [Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Ray, R., E-mail: juphyruma@gmail.com [Department of Physics, Jadavpur University, Kolkata 700 032 (India)

    2016-02-15

    Highlights: • Reduced graphene oxides (RGO) are prepared by two chemical routes. • Defects in RGO are characterized by Raman, FTIR and XPS studies. • Defects tailor colossal dielectricity in RGO. - Abstract: Reduced graphene oxide (RGO) is prepared in two different chemical routes where reduction of graphene oxide is performed by hydrazine hydrate and through high pressure in hydrothermal reactor. Samples are characterized by X-ray powdered diffraction (XRD), thermo gravimetric analysis (TGA), field emission scanning electron microscopy (FESEM) and tunneling electron microscopy (TEM). Types of defects are probed by Raman, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). UV–vis absorption reveals different optical band gaps of the two RGOs. Conductivity mechanism is studied through I–V measurements displaying different characteristic features which are addressed due to the presence of defects appeared in different synthesis. Significantly high value (∼10{sup 4}) of dielectric permittivity at 10 MHz is attractive for technological application which could be tuned by the defects present in RGO.

  11. A conceptual model for the fuel oxidation of defective fuel

    International Nuclear Information System (INIS)

    Higgs, J.D.; Lewis, B.J.; Thompson, W.T.; He, Z.

    2007-01-01

    A mechanistic conceptual model has been developed to predict the fuel oxidation behaviour in operating defective fuel elements for water-cooled nuclear reactors. This theoretical work accounts for gas-phase transport and sheath reactions in the fuel-to-sheath gap to determine the local oxygen potential. An improved thermodynamic analysis has also been incorporated into the model to describe the equilibrium state of the oxidized fuel. The fuel oxidation kinetics treatment accounts for multi-phase transport including normal diffusion and thermodiffusion for interstitial oxygen migration in the solid, as well as gas-phase transport in the fuel pellet cracks. The fuel oxidation treatment is further coupled to a heat conduction equation. A numerical solution of the coupled transport equations is obtained by a finite-element technique with the FEMLAB 3.1 software package. The model is able to provide radial-axial profiles of the oxygen-to-uranium ratio and the fuel temperatures as a function of time in the defective element for a wide range of element powers and defect sizes. The model results are assessed against coulometric titration measurements of the oxygen-to-metal profile for pellet samples taken from ten spent defective elements discharged from the National Research Universal Reactor at the Chalk River Laboratories and commercial reactors

  12. Mitochondrial fatty acid oxidation defects--remaining challenges

    DEFF Research Database (Denmark)

    Gregersen, Niels; Andresen, Brage S; Pedersen, Christina B

    2008-01-01

    Mitochondrial fatty acid oxidation defects have been recognized since the early 1970s. The discovery rate has been rather constant, with 3-4 'new' disorders identified every decade and with the most recent example, ACAD9 deficiency, reported in 2007. In this presentation we will focus on three...

  13. Defects and defect generation in oxide layer of ion implanted silicon-silicon dioxide structures

    CERN Document Server

    Baraban, A P

    2002-01-01

    One studies mechanism of generation of defects in Si-SiO sub 2 structure oxide layer as a result of implantation of argon ions with 130 keV energy and 10 sup 1 sup 3 - 3.2 x 10 sup 1 sup 7 cm sup - sup 2 doses. Si-SiO sub 2 structures are produced by thermal oxidation of silicon under 950 deg C temperature. Investigations were based on electroluminescence technique and on measuring of high-frequency volt-farad characteristics. Increase of implantation dose was determined to result in spreading of luminosity centres and in its maximum shifting closer to boundary with silicon. Ion implantation was shown, as well, to result in increase of density of surface states at Si-SiO sub 2 interface. One proposed model of defect generation resulting from Ar ion implantation into Si-SiO sub 2

  14. Defects and properties of cadmium oxide based transparent conductors

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Kin Man, E-mail: kinmanyu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Kowloon (Hong Kong); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Detert, D. M.; Dubon, O. D. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States); Chen, Guibin [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Physics Department and Jiangsu Key Laboratory for Chemistry of Low Dimensional Materials, Huaiyin Normal University, Jiangsu 223300 (China); Zhu, Wei [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics and The Center for Physical Experiments, University of Science and Technology of China, Hefei, Anhui 230026 (China); Liu, Chaoping [Department of Physics and Materials Science, City University of Hong Kong, Kowloon (Hong Kong); Grankowska, S. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Institute of Experimental Physics (IEP UW), Warsaw University, Warsaw (Poland); Hsu, L. [Department of Postsecondary Teaching and Learning, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Walukiewicz, Wladek [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2016-05-14

    Transparent conductors play an increasingly important role in a number of semiconductor technologies. This paper reports on the defects and properties of Cadmium Oxide, a transparent conducting oxide which can be potentially used for full spectrum photovoltaics. We carried out a systematic investigation on the effects of defects in CdO thin films undoped and intentionally doped with In and Ga under different deposition and annealing conditions. We found that at low growth temperatures (<200 °C), sputter deposition tends to trap both oxygen vacancies and compensating defects in the CdO film resulting in materials with high electron concentration of ∼2 × 10{sup 20}/cm{sup 3} and mobility in the range of 40–100 cm{sup 2}/V s. Thermal annealing experiments in different ambients revealed that the dominating defects in sputtered CdO films are oxygen vacancies. Oxygen rich CdO films grown by sputtering with increasing O{sub 2} partial pressure in the sputter gas mixture results in films with resistivity from ∼4 × 10{sup −4} to >1 Ω cm due to incorporation of excess O in the form of O-related acceptor defects, likely to be O interstitials. Intentional doping with In and Ga donors leads to an increase of both the electron concentration and the mobility. With proper doping CdO films with electron concentration of more than 10{sup 21 }cm{sup −3} and electron mobility higher than 120 cm{sup 2}/V s can be achieved. Thermal annealing of doped CdO films in N{sub 2} ambient can further improve the electrical properties by removing native acceptors and improving film crystallinity. Furthermore, the unique doping behavior and electrical properties of CdO were explored via simulations based on the amphoteric defect model. A comparison of the calculations and experimental results show that the formation energy of native donors and acceptors at the Fermi stabilization energy is ∼1 eV and that the mobility of sputtered deposited CdO is limited

  15. Defects and properties of cadmium oxide based transparent conductors

    International Nuclear Information System (INIS)

    Yu, Kin Man; Detert, D. M.; Dubon, O. D.; Chen, Guibin; Zhu, Wei; Liu, Chaoping; Grankowska, S.; Hsu, L.; Walukiewicz, Wladek

    2016-01-01

    Transparent conductors play an increasingly important role in a number of semiconductor technologies. This paper reports on the defects and properties of Cadmium Oxide, a transparent conducting oxide which can be potentially used for full spectrum photovoltaics. We carried out a systematic investigation on the effects of defects in CdO thin films undoped and intentionally doped with In and Ga under different deposition and annealing conditions. We found that at low growth temperatures (<200 °C), sputter deposition tends to trap both oxygen vacancies and compensating defects in the CdO film resulting in materials with high electron concentration of ∼2 × 10 20 /cm 3 and mobility in the range of 40–100 cm 2 /V s. Thermal annealing experiments in different ambients revealed that the dominating defects in sputtered CdO films are oxygen vacancies. Oxygen rich CdO films grown by sputtering with increasing O 2 partial pressure in the sputter gas mixture results in films with resistivity from ∼4 × 10 −4 to >1 Ω cm due to incorporation of excess O in the form of O-related acceptor defects, likely to be O interstitials. Intentional doping with In and Ga donors leads to an increase of both the electron concentration and the mobility. With proper doping CdO films with electron concentration of more than 10 21  cm −3 and electron mobility higher than 120 cm 2 /V s can be achieved. Thermal annealing of doped CdO films in N 2 ambient can further improve the electrical properties by removing native acceptors and improving film crystallinity. Furthermore, the unique doping behavior and electrical properties of CdO were explored via simulations based on the amphoteric defect model. A comparison of the calculations and experimental results show that the formation energy of native donors and acceptors at the Fermi stabilization energy is ∼1 eV and that the mobility of sputtered deposited CdO is limited by a background acceptor concentration of

  16. Short, medium and long term consequences of inadequate defect fuel management

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, J.G. [CANTECH Associates Limited, Burlington, Ontario (Canada); Nashiem, R.; McQueen, M.; Ma, G. [Bruce Power, Tiverton, Ontario (Canada)

    2011-07-01

    Defect fuel pencils result in short, medium and long term consequences to the environment within and external to the nuclear power station. The paper will describe these consequences and specify the Defect Fuel Management Practices required to avoid these consequences. (author)

  17. Short, medium and long term consequences of inadequate defect fuel management

    International Nuclear Information System (INIS)

    Roberts, J.G.; Nashiem, R.; McQueen, M.; Ma, G.

    2011-01-01

    Defect fuel pencils result in short, medium and long term consequences to the environment within and external to the nuclear power station. The paper will describe these consequences and specify the Defect Fuel Management Practices required to avoid these consequences. (author)

  18. Short, medium and long term consequences of inadequate defect fuel management

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, J.G., E-mail: alchemy@tnt21.com [CANTECH Associates Ltd., Burlington, Ontario (Canada); Nashiem, R.; McQueen, M.; Ma, G., E-mail: Rod.nashiem@brucepower.com, E-mail: Maureen.mcqueen@brucepower.com, E-mail: guoping.ma@brucepower.com [Bruce Power, Tiverton (Canada)

    2010-07-01

    Defect fuel pencils result in short, medium and long term consequences to the environment within and external to the nuclear power station. The paper will describe these consequences and specify the Defect Fuel Management Practices required to avoid these consequences. (author)

  19. Short, medium and long term consequences of inadequate defect fuel management

    International Nuclear Information System (INIS)

    Roberts, J.G.; Nashiem, R.; McQueen, M.; Ma, G.

    2010-01-01

    Defect fuel pencils result in short, medium and long term consequences to the environment within and external to the nuclear power station. The paper will describe these consequences and specify the Defect Fuel Management Practices required to avoid these consequences. (author)

  20. Defects and oxidation of group-III monochalcogenide monolayers

    Science.gov (United States)

    Guo, Yu; Zhou, Si; Bai, Yizhen; Zhao, Jijun

    2017-09-01

    Among various two-dimensional (2D) materials, monolayer group-III monochalcogenides (GaS, GaSe, InS, and InSe) stand out owing to their potential applications in microelectronics and optoelectronics. Devices made of these novel 2D materials are sensitive to environmental gases, especially O2 molecules. To address this critical issue, here we systematically investigate the oxidization behaviors of perfect and defective group-III monochalcogenide monolayers by first-principles calculations. The perfect monolayers show superior oxidation resistance with large barriers of 3.02-3.20 eV for the dissociation and chemisorption of O2 molecules. In contrast, the defective monolayers with single chalcogen vacancy are vulnerable to O2, showing small barriers of only 0.26-0.36 eV for the chemisorption of an O2 molecule. Interestingly, filling an O2 molecule to the chalcogen vacancy of group-III monochalcogenide monolayers could preserve the electronic band structure of the perfect system—the bandgaps are almost intact and the carrier effective masses are only moderately disturbed. On the other hand, the defective monolayers with single vacancies of group-III atoms carry local magnetic moments of 1-2 μB. These results help experimental design and synthesis of group-III monochalcogenides based 2D devices with high performance and stability.

  1. Defective [U-14 C] palmitic acid oxidation in Duchenne muscular dystrophy

    International Nuclear Information System (INIS)

    Carroll, J.E.; Norris, B.J.; Brooke, M.H.

    1985-01-01

    Compared with normal skeletal muscle, muscle from patients with Duchenne dystrophy had decreased [U-14 C] palmitic acid oxidation. [1-14 C] palmitic acid oxidation was normal. These results may indicate a defect in intramitochondrial fatty acid oxidation

  2. Defective (U-14 C) palmitic acid oxidation in Duchenne muscular dystrophy

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, J.E.; Norris, B.J.; Brooke, M.H.

    1985-01-01

    Compared with normal skeletal muscle, muscle from patients with Duchenne dystrophy had decreased (U-14 C) palmitic acid oxidation. (1-14 C) palmitic acid oxidation was normal. These results may indicate a defect in intramitochondrial fatty acid oxidation.

  3. Defect Engineering and Interface Phenomena in Tin Oxide

    KAUST Repository

    Albar, Arwa

    2017-04-05

    The advance in transparent electronics requires high-performance transparent conducting oxide materials. The microscopic properties of these materials are sensitive to the presence of defects and interfaces and thus fundamental understanding is required for materials engineering. In this thesis, first principles density functional theory is used to investigate the possibility of tuning the structural, electronic and magnetic properties of tin oxide by means of defects and interfaces. Our aim is to reveal unique properties and the parameters to control them as well as to explain the origin of unique phenomena in oxide materials. The stability of native defect in tin monoxide (SnO) under strain is investigated using formation energy calculations. We find that the conductivity (which is controlled by native defects) can be switched from p-type to either n-type or undoped semiconducting by means of applied pressure. We then target inducing magnetism in SnO by 3d transition metal doping. We propose that V doping is efficient to realize spin polarization at high temperature. We discuss different tin oxide interfaces. Metallic states are found to form at the SnO/SnO2 interface with electronic properties that depend on the interface terminations. The origin of these states is explained in terms of charge transfer caused by chemical bonding and band alignment. For the SnO/SnO2 heterostructure, we observe the formation of a two dimensional hole gas at the interface, which is surprising as it cannot be explained by the standard polar catastrophe model. Thus, we propose a charge density discontinuity model to explain our results. The model can be generalized to other polar-polar interfaces. Motivated by technological applications, the electronic and structural properties of the MgO (100)/SnO2 (110) interface are investigated. Depending on the interface termination, we observe the formation of a two dimensional electron gas or spin polarized hole gas. Aiming to identify further

  4. Defect-induced conductance oscillations in short atomic chains

    International Nuclear Information System (INIS)

    Wawrzyniak-Adamczewska, M; Kostyrko, T

    2012-01-01

    Electronic transport through a junction made of two gold electrodes connected with a gold chain containing a silver impurity is analyzed with a tight binding model and the density-functional theory. It is shown that the conductance depends in a simple way on the position of the impurity in the chain and the parity of the total number of atoms of the chain. For an odd chain the conductance takes on a higher value when the Ag impurity substitutes an even Au atom in the chain, and a lower one for an odd position of the Ag atom. In the case of an even chain the conductance hardly depends on the position of the Ag atom. This new kind of a defect-induced parity oscillation of the conductance is significantly more prominent than the well-known even-odd effect related to the dependence of the conductance on the parity of number of atoms in perfect chains. (paper)

  5. Radiation induced defects and thermoluminescence mechanism in aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Atobe, K.; Kobayashi, T.; Awata, T. [Naruto Univ. of Education, Tokushima (Japan); Okada, M. [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst; Nakagawa, M. [Kagawa Univ., Faculty of Education, Takamatsu, Kagawa (Japan)

    2001-01-01

    The thermoluminescence of the irradiated aluminum oxides were measured to study the radiation induced defects and their behaviors. Neutron and {gamma}-ray irradiation were performed for a shingle crystal of the high purity aluminum oxide. The thermoluminescence glow curve and its activation energy were measured. The spectroscopy measurement on the thermoluminescence and the absorption are also carried out. The observed 430 and 340 nm peaks are discussed relating to the F{sup +} and F centers, respectively. Activation state of the F center transits to 3P state through 1P state by emitting phonons. Trapped electron on 3P state emits phonon of 2.9 eV (430 nm) during transition to the ground state. The above reaction can be written by the equation. F{sup +} + e {yields} (F){sup *} {yields} F + h{nu}(2.9 eV, 470 nm). (Katsuta, H.)

  6. Defect production in simulated cascades: Cascade quenching and short-term annealing

    International Nuclear Information System (INIS)

    Heinisch, H.L.

    1983-01-01

    Defect production in displacement cascades in copper has been modeled using the MARLOWE code to generate cascades and the stochastic annealing code ALSOME to simulate cascade quenching and short-term annealing of isolated cascades. Quenching is accomplished by using exaggerated values for defect mobilities and for critical reaction distances in ALSOME for a very short time. The quenched cascades are then short-term annealed with normal parameter values. The quenching parameter values were empirically determined by comparison with results of resistivity measurements. Throughout the collisional, quenching and short-term annealing phases of cascade development, the high energy cascades continue to behave as a collection of independent lower energy lobes. For recoils above about 30 keV the total number of defects and the numbers of free defects scale with the damage energy. As the energy decreases from 30 keV, defect production varies with the changing nature of the cascade configuration, resulting in more defects per unit damage energy. The simulated annealing of a low fluence of interacting cascades revealed an interstitial shielding effect on depleted zones during Stage I recovery. (orig.)

  7. Modelling ionising radiation induced defect generation in bipolar oxides with gated diodes

    International Nuclear Information System (INIS)

    Barnaby, H.J.; Cirba, C.; Schrimpf, R.D.; Kosier, St.; Fouillat, P.; Montagner, X.

    1999-01-01

    Radiation-induced oxide defects that degrade electrical characteristics of bipolar junction transistor (BJTs) can be measured with the use of gated diodes. The buildup of defects and their effect on device radiation response are modeled with computer simulation. (authors)

  8. A Short Review on Journal Impact Factor; Significance and Defects

    Directory of Open Access Journals (Sweden)

    Masoud Eisa Khajelou

    2015-08-01

    Full Text Available Impact Factor (IF is considered as one of the most common subjects in academic environments. Individuals who would like to publish their productions and/or research results confront with various indicators, brands and labels that indicate relative importance, academic discipline and quality of journals. Diversity of the indicators induces confusion to select applicable journals and often, the authors would not be able to distinguish IF, ISI and their relations with the acceptance of the journal. Meanwhile, they have difficulties to find IF. Hence, this short paper aimed to provide useful information for authors to familiarize them with the concept of IF.​

  9. Dislocations and related defects in niobium oxide structures

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, J S; Hutchinson, J L; Lincoln, F J [Oxford Univ. (UK). Inorganic Chemistry Lab.

    1977-01-07

    Lattice images of the niobium oxides, structures based on the linkage of octahedral groups in continuous networks, occasionally contain features recognizable as dislocations. Since lattice imaging enables the microstructure to be resolved in greater detail, at the level of local structural organization, it is possible to determine the configuration, and also to infer the chemical composition, of dislocated areas. By treating the niobium oxide 'block' structures as superstructures of the ReO/sub 3/ (DO/sub 9/) type, the topology of dislocations can be expressed by relations between the insertion (or deletion) of one or more half-planes of cations, or of oxygen atoms only, changes in the number of crystallographic shear plane interfaces between blocks or columns, changes in (idealized) dimensions and any requisite distortion in the third dimension. Mapping the structure around a dislocation, from the lattice image, is directly equivalent to plotting the Burgers' circuit. In this way, the precise nature of a dislocating perturbation and its implications for the local chemical composition of the crystal can be directly identified. The method is exemplified by analysis of dislocations and of related extended defects of several types, associated with twinning phenomena, semicoherent intergrowth between different ReO/sub 3/-type superstructures and arrays building up a low angle boundary. The essential features of the analysis are not restricted to structures of the niobium oxide type, but can be extended to other types of polyhedron networks.

  10. Effect of the degree of oxidation and defects of graphene oxide on adsorption of Cu2+ from aqueous solution

    Science.gov (United States)

    Tan, Ping; Bi, Qi; Hu, Yongyou; Fang, Zheng; Chen, Yuancai; Cheng, Jianhua

    2017-11-01

    Graphene oxide (GO) is a promising adsorbent for heavy metal ions from water. However, the relationship between the degree of oxidation and defects of GO and the adsorption performance has been rarely reported. In this study, a series of GO with different degree of oxidation (GO1, GO5, GO6) and defects (GO1-GO4) were prepared by the improved Hummers method and were employed to explore the relationship between the degree of oxidation and defects of GO and the Cu2+ adsorption. The results showed that the adsorption of Cu2+ on GO was strongly dependent on the degree of oxidation and independent of the defects under various pH levels and ionic strength. The adsorption isotherms of Cu2+ on GO with different degree of oxidation and defects were well described by the Langmuir model and the maximum adsorption capacity of GO for Cu2+ increased with the improvement of the degree of oxidation but was independent of the defects, indicating that the adsorption of Cu2+ on GO was mainly proportional to the degree of oxidation but become insignificant in the structure integrity of aromatic matrixes, which might be due to the shielding effect of oxygen-containing groups. The adsorption of Cu2+ on GO with different degree of oxidation and defects reached an equilibrium state after 50 min, the adsorption kinetics followed the pseudo-second-order model and the adsorption process was controlled by the degree of oxidation.

  11. Intrinsic defect oriented visible region absorption in zinc oxide films

    Science.gov (United States)

    Rakhesh, V.; Shankar, Balakrishnan

    2018-05-01

    Zinc Oxide films were deposited on the glass substrate using vacuum arc sputtering technology. Films were prepared in oxygen ambience for 10mA and 15 mA deposition current separately. The UV-Visible spectroscopy of the samples showed that both samples possess sharp absorption near 3.5eV which is the characteristic band gap absorption energy of ZnO films. The absorption coefficient were calculated for the samples and the (αℎϑ)2 vs energy plot is drawn. The plot suggested that in addition to the sharp band edge absorption, the sample prepared at 10mA deposition current showed sharp absorption edge near 1.51eV and that at 15 mA showed absorption edge near 1.47eV. This refers to the presence of an intrinsic defect level which is likely to be deep in the band gap.

  12. Positron trapping at defects in copper oxide superconductors

    International Nuclear Information System (INIS)

    McMullen, T.; Jena, P.; Khanna, S.N.; Li, Y.; Jensen, K.O.

    1991-01-01

    Positron states and lifetimes at defects in the copper oxide superconductors La 2-x Sr x CuO 4 , YBa 2 Cu 3 O 7-x , and Bi 2 Sr 2 CaCu 2 O 8+x are calculated with use of the superposed-atom model. In the Bi 2 Sr 2 CaCu 2 O 8+x compound, we find that the smaller metal-ion vacancies appear to only bind positrons weakly, while missing oxygens do not trap positrons. In contrast, metal-ion vacancies in La 2-x Sr x CuO 4 and YBa 2 Cu 3 O 7-x bind positrons by ∼1 eV, and oxygen-related defects appear to be the weak-binding sites in these materials. The sites that bind positrons only weakly, by energies ∼k BT , are of particular interest in view of the complex temperature dependences of the annihilation characteristics that are observed in these materials

  13. SHORT COMMUNICATION MICROWAVE-ASSISTED OXIDATION ...

    African Journals Online (AJOL)

    a

    2Department of Chemistry, Faculty of Science, Imam Khomeini International ... Although the oxidation of organic compounds under non-aqueous conditions ... primary alcohols to aldehydes and secondary alcohols to ketones (Scheme 1). CH3.

  14. Diagnosis of Soft Spot Short Defects in Analog Circuits Considering the Thermal Behaviour of the Chip

    Directory of Open Access Journals (Sweden)

    Tadeusiewicz Michał

    2016-06-01

    Full Text Available The paper deals with fault diagnosis of nonlinear analogue integrated circuits. Soft spot short defects are analysed taking into account variations of the circuit parameters due to physical imperfections as well as self-heating of the chip. A method enabling to detect, locate and estimate the value of a spot defect has been developed. For this purpose an appropriate objective function was minimized using an optimization procedure based on the Fibonacci method. The proposed approach exploits DC measurements in the test phase, performed at a limited number of accessible points. For illustration three numerical examples are given.

  15. Ab initio study of point defects in magnesium oxide

    International Nuclear Information System (INIS)

    Gilbert, C. A.; Kenny, S. D.; Smith, R.; Sanville, E.

    2007-01-01

    Energetics of a variety of point defects in MgO have been considered from an ab initio perspective using density functional theory. The considered defects are isolated Schottky and Frenkel defects and interstitial pairs, along with a number of Schottky defects and di-interstitials. Comparisons were made between the density functional theory results and results obtained from empirical potential simulations and these generally showed good agreement. Both methodologies predicted the first nearest neighbor Schottky defects to be the most energetically favorable of the considered Schottky defects and that the first, second, and fifth nearest neighbor di-interstitials were of similar energy and were favored over the other di-interstitial configurations. Relaxed structures of the defects were analyzed, which showed that empirical potential simulations were accurately predicting the displacements of atoms surrounding di-interstitials, but were overestimating O atom displacement for Schottky defects. Transition barriers were computed for the defects using the nudged elastic band method. Vacancies and Schottky defects were found to have relatively high energy barriers, the majority of which were over 2 eV, in agreement with conclusions reached using empirical potentials. The lowest barriers for di-interstitial transitions were found to be for migration into a first nearest neighbor configuration. Charges were calculated using a Bader analysis and this found negligible charge transfer during the defect transitions and only small changes in the charges on atoms surrounding defects, indicating why fixed charge models work as well as they do

  16. Ectopic expression of Ptf1a induces spinal defects, urogenital defects, and anorectal malformations in Danforth's short tail mice.

    Directory of Open Access Journals (Sweden)

    Kei Semba

    Full Text Available Danforth's short tail (Sd is a semidominant mutation on mouse chromosome 2, characterized by spinal defects, urogenital defects, and anorectal malformations. However, the gene responsible for the Sd phenotype was unknown. In this study, we identified the molecular basis of the Sd mutation. By positional cloning, we identified the insertion of an early transposon in the Sd candidate locus approximately 12-kb upstream of Ptf1a. We found that insertion of the transposon caused overexpression of three neighboring genes, Gm13344, Gm13336, and Ptf1a, in Sd mutant embryos and that the Sd phenotype was not caused by disruption of an as-yet-unknown gene in the candidate locus. Using multiple knockout and knock-in mouse models, we demonstrated that misexpression of Ptf1a, but not of Gm13344 or Gm13336, in the notochord, hindgut, cloaca, and mesonephros was sufficient to replicate the Sd phenotype. The ectopic expression of Ptf1a in the caudal embryo resulted in attenuated expression of Cdx2 and its downstream target genes T, Wnt3a, and Cyp26a1; we conclude that this is the molecular basis of the Sd phenotype. Analysis of Sd mutant mice will provide insight into the development of the spinal column, anus, and kidney.

  17. Defect production in simulated cascades: cascade quenching and short-term annealing

    International Nuclear Information System (INIS)

    Heinisch, H.L.

    1982-01-01

    Defect production in high energy displacement cascades has been modeled using the computer code MARLOWE to generate the cascades and the stochastic computer code ALSOME to simulate the cascade quenching and short-term annealing of isolated cascades. The quenching is accomplished by using ALSOME with exaggerated values for defect mobilities and critical reaction distanes for recombination and clustering, which are in effect until the number of defect pairs is equal to the value determined from resistivity experiments at 4K. Then normal mobilities and reaction distances are used during short-term annealing to a point representative of Stage III recovery. Effects of cascade interactions at low fluences are also being investigated. The quenching parameter values were empirically determined for 30 keV cascades. The results agree well with experimental information throughout the range from 1 keV to 100 keV. Even after quenching and short-term annealing the high energy cascades behave as a collection of lower energy subcascades and lobes. Cascades generated in a crystal having thermal displacements were found to be in better agreement with experiments after quenching and annealing than those generated in a non-thermal crystal

  18. Dual passivation of intrinsic defects at the compound semiconductor/oxide interface using an oxidant and a reductant.

    Science.gov (United States)

    Kent, Tyler; Chagarov, Evgeniy; Edmonds, Mary; Droopad, Ravi; Kummel, Andrew C

    2015-05-26

    Studies have shown that metal oxide semiconductor field-effect transistors fabricated utilizing compound semiconductors as the channel are limited in their electrical performance. This is attributed to imperfections at the semiconductor/oxide interface which cause electronic trap states, resulting in inefficient modulation of the Fermi level. The physical origin of these states is still debated mainly because of the difficulty in assigning a particular electronic state to a specific physical defect. To gain insight into the exact source of the electronic trap states, density functional theory was employed to model the intrinsic physical defects on the InGaAs (2 × 4) surface and to model the effective passivation of these defects by utilizing both an oxidant and a reductant to eliminate metallic bonds and dangling-bond-induced strain at the interface. Scanning tunneling microscopy and spectroscopy were employed to experimentally determine the physical and electronic defects and to verify the effectiveness of dual passivation with an oxidant and a reductant. While subsurface chemisorption of oxidants on compound semiconductor substrates can be detrimental, it has been shown theoretically and experimentally that oxidants are critical to removing metallic defects at oxide/compound semiconductor interfaces present in nanoscale channels, oxides, and other nanostructures.

  19. Oxidation behavior of graphene-coated copper at intrinsic graphene defects of different origins.

    Science.gov (United States)

    Kwak, Jinsung; Jo, Yongsu; Park, Soon-Dong; Kim, Na Yeon; Kim, Se-Yang; Shin, Hyung-Joon; Lee, Zonghoon; Kim, Sung Youb; Kwon, Soon-Yong

    2017-11-16

    The development of ultrathin barrier films is vital to the advanced semiconductor industry. Graphene appears to hold promise as a protective coating; however, the polycrystalline and defective nature of engineered graphene hinders its practical applications. Here, we investigate the oxidation behavior of graphene-coated Cu foils at intrinsic graphene defects of different origins. Macro-scale information regarding the spatial distribution and oxidation resistance of various graphene defects is readily obtained using optical and electron microscopies after the hot-plate annealing. The controlled oxidation experiments reveal that the degree of structural deficiency is strongly dependent on the origins of the structural defects, the crystallographic orientations of the underlying Cu grains, the growth conditions of graphene, and the kinetics of the graphene growth. The obtained experimental and theoretical results show that oxygen radicals, decomposed from water molecules in ambient air, are effectively inverted at Stone-Wales defects into the graphene/Cu interface with the assistance of facilitators.

  20. A novel method for surface defect inspection of optic cable with short-wave infrared illuminance

    Science.gov (United States)

    Chen, Xiaohong; Liu, Ning; You, Bo; Xiao, Bin

    2016-07-01

    Intelligent on-line detection of cable quality is a crucial issue in optic cable factory, and defects on the surface of optic cable can dramatically depress cable grade. Manual inspection in optic cable quality cannot catch up with the development of optic cable industry due to its low detection efficiency and huge human cost. Therefore, real-time is highly demanded by industry in order to replace the subjective and repetitive process of manual inspection. For this reason, automatic cable defect inspection has been a trend. In this paper, a novel method for surface defect inspection of optic cable with short-wave infrared illuminance is presented. The special condition of short-wave infrared cannot only provide illumination compensation for the weak illumination environment, but also can avoid the problem of exposure when using visible light illuminance, which affects the accuracy of inspection algorithm. A series of image processing algorithms are set up to analyze cable image for the verification of real-time and veracity of the detection method. Unlike some existing detection algorithms which concentrate on the characteristics of defects with an active search way, the proposed method removes the non-defective areas of the image passively at the same time of image processing, which reduces a large amount of computation. OTSU algorithm is used to convert the gray image to the binary image. Furthermore, a threshold window is designed to eliminate the fake defects, and the threshold represents the considered minimum size of defects ε . Besides, a new regional suppression method is proposed to deal with the edge burrs of the cable, which shows the superior performance compared with that of Open-Close operation of mathematical morphological in the boundary processing. Experimental results of 10,000 samples show that the rates of miss detection and false detection are 2.35% and 0.78% respectively when ε equals to 0.5 mm, and the average processing period of one frame

  1. Oxide film defects in Al alloys and the formation of hydrogen- related porosity

    International Nuclear Information System (INIS)

    Griffiths, W D; Yue, Y; Gerrard, A J

    2016-01-01

    Double oxide film defects have also been held responsible for the origins of hydrogen porosity, where hydrogen dissolved in the Al melt passes into the interior atmosphere of the double oxide film defect causing it to inflate. However, this is in opposition to long- established evidence that H cannot readily diffuse through aluminium oxide. To investigate this further, samples of commercial purity Al were first degassed to remove their initial H content, and then heated to above their melting point and held in atmospheres of air and nitrogen respectively, to determine any differences in H pick-up. The experiment showed that samples held in an oxidising atmosphere, and having an oxide skin, picked up significantly less H than when the samples were held in a nitrogen atmosphere, which resulted in the formation of AlN in cracks in the oxide skin of the sample. It is suggested that double oxide film defects can give rise to hydrogen-related porosity, but this occurs more quickly when the oxygen in the original oxide film defect has been consumed by reaction with the surrounding melt and nitrogen reacts to form AlN, which is more permeable to H than alumina, more easily allowing the oxide film defect to give rise to a hydrogen pore. This is used to interpret results from an earlier synchrotron experiment, in which a small pore was seen to grow into a larger pore, while an adjacent large pore remained at a constant size. (paper)

  2. Behaviour of defective CANDU fuel: fuel oxidation kinetic and thermodynamic modelling

    International Nuclear Information System (INIS)

    Higgs, J.

    2005-01-01

    The thermal performance of operating CANDU fuel under defect conditions is affected by the ingress of heavy water into the fuel element. A mechanistic model has been developed to predict the extent of fuel oxidation in defective fuel and its affect on fuel thermal performance. A thermodynamic treatment of such oxidized fuel has been performed as a basis for the boundary conditions in the kinetic model. Both the kinetic and thermodynamic models have been benchmarked against recent experimental work. (author)

  3. Defects in Amorphous Semiconductors: The Case of Amorphous Indium Gallium Zinc Oxide

    Science.gov (United States)

    de Jamblinne de Meux, A.; Pourtois, G.; Genoe, J.; Heremans, P.

    2018-05-01

    Based on a rational classification of defects in amorphous materials, we propose a simplified model to describe intrinsic defects and hydrogen impurities in amorphous indium gallium zinc oxide (a -IGZO). The proposed approach consists of organizing defects into two categories: point defects, generating structural anomalies such as metal—metal or oxygen—oxygen bonds, and defects emerging from changes in the material stoichiometry, such as vacancies and interstitial atoms. Based on first-principles simulations, it is argued that the defects originating from the second group always act as perfect donors or perfect acceptors. This classification simplifies and rationalizes the nature of defects in amorphous phases. In a -IGZO, the most important point defects are metal—metal bonds (or small metal clusters) and peroxides (O - O single bonds). Electrons are captured by metal—metal bonds and released by the formation of peroxides. The presence of hydrogen can lead to two additional types of defects: metal-hydrogen defects, acting as acceptors, and oxygen-hydrogen defects, acting as donors. The impact of these defects is linked to different instabilities observed in a -IGZO. Specifically, the diffusion of hydrogen and oxygen is connected to positive- and negative-bias stresses, while negative-bias illumination stress originates from the formation of peroxides.

  4. Point defects and oxidation mechanism in cubic boron nitride

    International Nuclear Information System (INIS)

    Gorshin, A.P.; Shvajko-Shvajkovskij, V.E.

    1994-01-01

    A theoretical analysis of the defect formation in boron nitride by the Schottky mechanism within the framework of the quasi-chemical approximation method is carried out. On the base of solution of the disordering equations at different conditions of electroneutrality are obtained the dependences of defect concentrations in β-BN on the partial nitrogen pressure in equilibrium conditions. Experimental checking of the theoretical analysis proposed confirms the hypothesis on the presence of defects of nonstoichiometric origin in the β-BN anion sublattice

  5. Defect engineering of the electronic transport through cuprous oxide interlayers

    KAUST Repository

    Fadlallah, Mohamed M.

    2016-06-03

    The electronic transport through Au–(Cu2O)n–Au junctions is investigated using first-principles calculations and the nonequilibrium Green’s function method. The effect of varying the thickness (i.e., n) is studied as well as that of point defects and anion substitution. For all Cu2O thicknesses the conductance is more enhanced by bulk-like (in contrast to near-interface) defects, with the exception of O vacancies and Cl substitutional defects. A similar transmission behavior results from Cu deficiency and N substitution, as well as from Cl substitution and N interstitials for thick Cu2O junctions. In agreement with recent experimental observations, it is found that N and Cl doping enhances the conductance. A Frenkel defect, i.e., a superposition of an O interstitial and O substitutional defect, leads to a remarkably high conductance. From the analysis of the defect formation energies, Cu vacancies are found to be particularly stable, in agreement with earlier experimental and theoretical work.

  6. Use of porous silicon to minimize oxidation induced stacking fault defects in silicon

    International Nuclear Information System (INIS)

    Shieh, S.Y.; Evans, J.W.

    1992-01-01

    This paper presents methods for minimizing stacking fault defects, generated during oxidation of silicon, include damaging the back of the wafer or depositing poly-silicon on the back. In either case a highly defective structure is created and this is capable of gettering either self-interstitials or impurities which promote nucleation of stacking fault defects. A novel method of minimizing these defects is to form a patch of porous silicon on the back of the wafer by electrochemical etching. Annealing under inert gas prior to oxidation may then result in the necessary gettering. Experiments were carried out in which wafers were subjected to this treatment. Subsequent to oxidation, the wafers were etched to remove oxide and reveal defects. The regions of the wafer adjacent to the porous silicon patch were defect-free, whereas remote regions had defects. Deep level transient spectroscopy has been used to examine the gettering capability of porous silicon, and the paper discusses the mechanism by which the porous silicon getters

  7. The defect chemistry of nitrogen in oxides: A review of experimental and theoretical studies

    International Nuclear Information System (INIS)

    Polfus, Jonathan M.; Norby, Truls; Haugsrud, Reidar

    2013-01-01

    Incorporation of nitrogen into oxides has in recent years received increased attention as a variable for tuning their functional properties. A vast number of reports have been devoted to improving the photocatalytic properties of TiO 2 , p-type charge carrier concentration in ZnO and the ionic transport properties of ZrO 2 by nitrogen doping. In comparison, the fundamentals of the nitrogen related defect chemistry for a wider range of oxides have been less focused upon. In the present contribution, we review experimental and computational investigations of the nitrogen related defect chemistry of insulating and semiconducting oxides. The interaction between nitrogen and protons is important and emphasized. Specifically, the stability of nitrogen defects such as N O / , NH O × and (NH 2 ) O • is evaluated under various conditions and their atomistic and electronic structure is presented. A final discussion is devoted to the role of nitrogen with respect to transport properties and photocatalytic activity of oxides. - Graphical abstract: Experimental and theoretical investigations of the nitrogen related defect chemistry of a range of wide band gap oxides is reviewed. The interaction between nitrogen dopants and protons is emphasized and described through the atomistic and electronic structure as well as defect chemical processes involving NH and NH 2 defects. Consequently, the physical properties of oxides containing such species are discussed with respect to e.g., diffusion and photocatalytic properties. Highlights: ► Experimental and theoretical investigations of the nitrogen and hydrogen related defect chemistry of wide band gap oxides is reviewed. ► The interaction between nitrogen dopants and protons is important and emphasized. ► Diffusion and photocatalytic properties of N-doped oxides are discussed.

  8. Ab-initio modelling of thermodynamics and kinetics of point defects in indium oxide

    International Nuclear Information System (INIS)

    Agoston, Peter; Klein, Andreas; Albe, Karsten; Erhart, Paul

    2008-01-01

    The electrical and optical properties of indium oxide films strongly vary with the processing parameters. Especially the oxygen partial pressure and temperature determine properties like electrical conductivity, composition and transparency. Since this material owes its remarkable properties like the intrinsic n-type conductivity to its defect chemistry, it is important to understand both, the equilibrium defect thermodynamics and kinetics of the intrinsic point defects. In this contribution we present a defect model based on DFT total energy calculations using the GGA+U method. Further, the nudged elastic band method is employed in order to obtain a set of migration barriers for each defect species. Due to the complicated crystal structure of indium oxide a Kinetic Monte-Carlo algorithm was implemented, which allows to determine diffusion coefficients. The bulk tracer diffusion constant is predicted as a function of oxygen partial pressure, Fermi level and temperature for the pure material

  9. Regularities of radiation defects build up on oxide materials surface; Zakonomernosti nakopleniya radiatsionnykh defektov na poverkhnosti oksidnykh materialov

    Energy Technology Data Exchange (ETDEWEB)

    Bitenbaev, M I; Polyakov, A I [Fiziko-Tekhnicheskij Inst., Almaty (Kazakhstan); Tuseev, T [Inst. Yadernoj Fiziki, Almaty (Kazakhstan)

    2005-07-01

    Analysis of experimental data by radiation defects study on different oxide elements (silicon, beryllium, aluminium, rare earth elements) irradiated by the photo-, gamma-, neutron-, alpha- radiation, protons and helium ions show, that gas adsorption process on the surface centers and radiation defects build up in metal oxide correlated between themselves. These processes were described by the equivalent kinetic equations for analysis of radiation defects build up in the different metal oxides. It was revealed in the result of the analysis: number of radiation defects are droningly increasing up to limit value with the treatment temperature growth. Constant of radicals death at ionizing radiation increases as well. Amount of surface defects in different oxides defining absorbing activity of these materials looks as: silicon oxide{yields}beryllium oxide{yields}aluminium oxide. So it was found, that most optimal material for absorbing system preparation is silicon oxide by it power intensity and berylium oxide by it adsorption efficiency.

  10. The influence of initial defects on mechanical stress and deformation distribution in oxidized silicon

    Directory of Open Access Journals (Sweden)

    Kulinich O. A.

    2008-10-01

    Full Text Available The near-surface silicon layers in silicon – dioxide silicon systems with modern methods of research are investigated. It is shown that these layers have compound structure and their parameters depend on oxidation and initial silicon parameters. It is shown the influence of initial defects on mechanical stress and deformation distribution in oxidized silicon.

  11. Defects in zinc oxide grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Francis C.C., E-mail: ccling@hku.hk [Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Wang, Zilan; Ping Ho, Lok; Younas, M. [Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Anwand, W.; Wagner, A. [Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); Su, S.C. [Institute of Optoelectronic Material and Technology, South China Normal University, Guangzhou 510631 (China); Shan, C.X. [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)

    2016-01-01

    ZnO films are grown on c-plane sapphire using the pulsed laser deposition method. Systematic studies on the effects of annealing are performed to understand the thermal evolutions of the defects in the films. Particular attention is paid to the discussions of the ZnO/sapphire interface thermal stability, the Zn-vacancy related defects having different microstructures, the origins of the green luminescence (∼2.4–2.5 eV) and the near band edge (NBE) emission at 3.23 eV.

  12. Defect engineering of the electronic transport through cuprous oxide interlayers

    KAUST Repository

    Fadlallah, Mohamed M.; Eckern, Ulrich; Schwingenschlö gl, Udo

    2016-01-01

    The electronic transport through Au–(Cu2O)n–Au junctions is investigated using first-principles calculations and the nonequilibrium Green’s function method. The effect of varying the thickness (i.e., n) is studied as well as that of point defects

  13. Influence of defects on the ordering degree of nanopores made from anodic aluminum oxide

    International Nuclear Information System (INIS)

    Yu Wenhui; Fei Guangtao; Chen Xiaomeng; Xue Fanghong; Xu Xijin

    2006-01-01

    Anodic aluminum oxide (AAO) templates with highly ordered nanoporous structure were fabricated by means of the electrochemical anodization under the constant anodic voltage and electrolyte temperature. The dependence of the ordering degree of nanopores on the point defects, dislocation configuration and grain boundary of aluminum is qualitatively analyzed. Experiment results show that the size of the ordered region of nanopores depends strongly on the point defects, dislocation cell configuration

  14. Are Soft Short Tests Good Indicators of Internal Li-ion Cell Defects?

    Science.gov (United States)

    Jeevarajan, J.; Chung, J.-S.; Jung, K.; Park, J.

    2013-01-01

    The self discharge test at full state of charge, may not be a good one to detect subtle defects since the li-ion chemistry has the highest self discharge at full state of charge. One should characterize self discharge versus storage time for each cell manufacturer/design to differentiate between normal self discharge and that due to a subtle manufacturing defect. The various soft short test methods indicate that if this test is carried out at full discharge (0% SOC) with all capacity removed (by lowering the current load in a stepwise manner to the same end of discharge voltage), then the cells need to be placed in storage for more than 72 hours to get a good analysis on the presence of subtle defects since it takes more than 72 hours to achieve voltage stabilization. If the cells are to be charged up even to a small percentage (ex. 1%), 72 hours are sufficient to determine issues. However, the pass/fail criteria should be based on a valid OCV decline. Less than 10 mV voltage decline is not a good method to detect subtle defects. As mentioned in the first bullet, self discharge is a competing reaction when a charge is introduced and hence a characterization of the self discharge versus storage time is required to fully correlate voltage decline to a failure due to a subtle defect. Soft short test method cannot be relied on for defect detection because cells with and without voltage decline seemed to have similar defects and characteristics. Screening methods such as internal resistance and capacity as well as a 3-sigma range for OCV, mass and dimensions should be used to screen out outliers. A very critical aspect in the understanding of subtle defects is to carry out destructive analysis of cells from every lot to confirm the quality of production and screen all cells and batteries in a stringent manner to have a high quality set of flight cells. Self Discharge Test: Fully charged cells shall be placed in Open circuit stand for 72 hours (OCV measurement twice a

  15. 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...

  16. Genetic defects in the oxidative phosphorylation (OXPHOS) system.

    NARCIS (Netherlands)

    Janssen, R.J.R.J.; Heuvel, L.P.W.J. van den; Smeitink, J.A.M.

    2004-01-01

    The oxidative phosphorylation (OXPHOS) system consists of five multiprotein complexes and two mobile electron carriers embedded in the lipid bilayer of the mitochondrial inner membrane. With the exception of complex II and the mobile carriers, the other parts of the OXPHOS system are under dual

  17. Study of defect generated visible photoluminescence in zinc oxide nano-particles prepared using PVA templates

    Energy Technology Data Exchange (ETDEWEB)

    Oudhia, A. [Department of Physics, Government V.Y.T. PG. Autonomous College, Durg, 491001 C.G. (India); Choudhary, A., E-mail: aarti.bhilai@gmail.com [Department of Physics, Government V.Y.T. PG. Autonomous College, Durg, 491001 C.G. (India); Sharma, S.; Aggrawal, S. [Department of Physics, Government V.Y.T. PG. Autonomous College, Durg, 491001 C.G. (India); Dhoble, S.J. [RTM University Nagpur, Maharashtra (India)

    2014-10-15

    Intrinsic defect generated photoluminescence (PL) in zinc oxide nanoparticles (NPs) obtained by a PVA template based wet-chemical process has been studied. A good controllability was achieved on the surface defects, structure and the morphology of ZnO NPs through the variation of solvents used in synthesis. The PL emission strongly depended on the defect structure and morphology. SEM, XRD, annealing and PL excitation studies were used to analyze the types of defects involved in the visible emission as well as the defect concentration. The mechanism for the blue, green and yellow emissions was proposed. The spectral content of the visible emission was controlled through generation/removal of defects through the shape transformation or annealing by focusing on defect origins and broad controls. - Highlights: • ZnO nanoparticles were synthesized using poly-vinyl alcohol template in various solvents. • The structure and morphology of ZnO nanoparticles were depended on dielectric constant and boiling point of solvents. • Photoluminescence properties of ZnO nanoparticles were studied. • Maximum optical absorbance and Photoluminescence intensity were found in ethanolic preparation. • ZnO nanoparticles were annealed at different temperatures for detection of defect emission.

  18. Slow Replication Fork Velocity of Homologous Recombination-Defective Cells Results from Endogenous Oxidative Stress

    Science.gov (United States)

    Magdalou, Indiana; Machon, Christelle; Dardillac, Elodie; Técher, Hervé; Guitton, Jérôme; Debatisse, Michelle; Lopez, Bernard S.

    2016-01-01

    Replications forks are routinely hindered by different endogenous stresses. Because homologous recombination plays a pivotal role in the reactivation of arrested replication forks, defects in homologous recombination reveal the initial endogenous stress(es). Homologous recombination-defective cells consistently exhibit a spontaneously reduced replication speed, leading to mitotic extra centrosomes. Here, we identify oxidative stress as a major endogenous source of replication speed deceleration in homologous recombination-defective cells. The treatment of homologous recombination-defective cells with the antioxidant N-acetyl-cysteine or the maintenance of the cells at low O2 levels (3%) rescues both the replication fork speed, as monitored by single-molecule analysis (molecular combing), and the associated mitotic extra centrosome frequency. Reciprocally, the exposure of wild-type cells to H2O2 reduces the replication fork speed and generates mitotic extra centrosomes. Supplying deoxynucleotide precursors to H2O2-exposed cells rescued the replication speed. Remarkably, treatment with N-acetyl-cysteine strongly expanded the nucleotide pool, accounting for the replication speed rescue. Remarkably, homologous recombination-defective cells exhibit a high level of endogenous reactive oxygen species. Consistently, homologous recombination-defective cells accumulate spontaneous γH2AX or XRCC1 foci that are abolished by treatment with N-acetyl-cysteine or maintenance at 3% O2. Finally, oxidative stress stimulated homologous recombination, which is suppressed by supplying deoxynucleotide precursors. Therefore, the cellular redox status strongly impacts genome duplication and transmission. Oxidative stress should generate replication stress through different mechanisms, including DNA damage and nucleotide pool imbalance. These data highlight the intricacy of endogenous replication and oxidative stresses, which are both evoked during tumorigenesis and senescence initiation

  19. Slow Replication Fork Velocity of Homologous Recombination-Defective Cells Results from Endogenous Oxidative Stress.

    Directory of Open Access Journals (Sweden)

    Therese Wilhelm

    2016-05-01

    Full Text Available Replications forks are routinely hindered by different endogenous stresses. Because homologous recombination plays a pivotal role in the reactivation of arrested replication forks, defects in homologous recombination reveal the initial endogenous stress(es. Homologous recombination-defective cells consistently exhibit a spontaneously reduced replication speed, leading to mitotic extra centrosomes. Here, we identify oxidative stress as a major endogenous source of replication speed deceleration in homologous recombination-defective cells. The treatment of homologous recombination-defective cells with the antioxidant N-acetyl-cysteine or the maintenance of the cells at low O2 levels (3% rescues both the replication fork speed, as monitored by single-molecule analysis (molecular combing, and the associated mitotic extra centrosome frequency. Reciprocally, the exposure of wild-type cells to H2O2 reduces the replication fork speed and generates mitotic extra centrosomes. Supplying deoxynucleotide precursors to H2O2-exposed cells rescued the replication speed. Remarkably, treatment with N-acetyl-cysteine strongly expanded the nucleotide pool, accounting for the replication speed rescue. Remarkably, homologous recombination-defective cells exhibit a high level of endogenous reactive oxygen species. Consistently, homologous recombination-defective cells accumulate spontaneous γH2AX or XRCC1 foci that are abolished by treatment with N-acetyl-cysteine or maintenance at 3% O2. Finally, oxidative stress stimulated homologous recombination, which is suppressed by supplying deoxynucleotide precursors. Therefore, the cellular redox status strongly impacts genome duplication and transmission. Oxidative stress should generate replication stress through different mechanisms, including DNA damage and nucleotide pool imbalance. These data highlight the intricacy of endogenous replication and oxidative stresses, which are both evoked during tumorigenesis and

  20. Slow Replication Fork Velocity of Homologous Recombination-Defective Cells Results from Endogenous Oxidative Stress.

    Science.gov (United States)

    Wilhelm, Therese; Ragu, Sandrine; Magdalou, Indiana; Machon, Christelle; Dardillac, Elodie; Técher, Hervé; Guitton, Jérôme; Debatisse, Michelle; Lopez, Bernard S

    2016-05-01

    Replications forks are routinely hindered by different endogenous stresses. Because homologous recombination plays a pivotal role in the reactivation of arrested replication forks, defects in homologous recombination reveal the initial endogenous stress(es). Homologous recombination-defective cells consistently exhibit a spontaneously reduced replication speed, leading to mitotic extra centrosomes. Here, we identify oxidative stress as a major endogenous source of replication speed deceleration in homologous recombination-defective cells. The treatment of homologous recombination-defective cells with the antioxidant N-acetyl-cysteine or the maintenance of the cells at low O2 levels (3%) rescues both the replication fork speed, as monitored by single-molecule analysis (molecular combing), and the associated mitotic extra centrosome frequency. Reciprocally, the exposure of wild-type cells to H2O2 reduces the replication fork speed and generates mitotic extra centrosomes. Supplying deoxynucleotide precursors to H2O2-exposed cells rescued the replication speed. Remarkably, treatment with N-acetyl-cysteine strongly expanded the nucleotide pool, accounting for the replication speed rescue. Remarkably, homologous recombination-defective cells exhibit a high level of endogenous reactive oxygen species. Consistently, homologous recombination-defective cells accumulate spontaneous γH2AX or XRCC1 foci that are abolished by treatment with N-acetyl-cysteine or maintenance at 3% O2. Finally, oxidative stress stimulated homologous recombination, which is suppressed by supplying deoxynucleotide precursors. Therefore, the cellular redox status strongly impacts genome duplication and transmission. Oxidative stress should generate replication stress through different mechanisms, including DNA damage and nucleotide pool imbalance. These data highlight the intricacy of endogenous replication and oxidative stresses, which are both evoked during tumorigenesis and senescence initiation

  1. Point defects and irradiation in oxides: simulations at the atomic scale

    International Nuclear Information System (INIS)

    Crocombette, J.P.

    2005-12-01

    The studies done by Jean-Paul Crocombette between 1996 and 2005 in the Service de Recherches de Metallurgie Physique of the Direction de l'Energie Nucleaire in Saclay are presented in this Habilitation thesis. These works were part of the material science researches on the ageing, especially under irradiation, of oxides of interest for the nuclear industry. In this context simulation studies at the atomic scale were performed on two elementary components of ageing under irradiation : point defects and displacement cascades ; using two complementary simulation techniques : ab initio electronic structure calculations and empirical potential molecular dynamics. The first part deals with point defects : self defects (vacancies or interstitials) or hetero-atomic dopants. One first recalls the energetics of such defects in oxides, the specific features of defects calculations and the expected accuracy of these calculations. Then one presents the results obtained on uranium dioxide, oxygen in silver and amorphous silica. The second part tackles the modelling of disintegration recoil nuclei in various?displacement cascades created by crystalline matrices for actinide waste disposal. Cascade calculations give access to the amorphization mechanisms under irradiation of these materials. One thus predicts that the amorphization in zircon takes place directly in the tracks whereas in lanthanum zirconate, the amorphization proceeds through the accumulation of point defects. Finally the prospects of these studies are discussed. (author)

  2. 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.

  3. Synthesis and structural characterization of defect spinels in the Lithium-Manganese-Oxide system

    CSIR Research Space (South Africa)

    Thackeray, MM

    1993-10-01

    Full Text Available Lithium-manganese-oxides prepared at moderate temperatures are under investigation as insertion electrodes for rechargeable lithium batteries. The structures of two defect-spinel compounds synthesised by the reaction of MnCO3 and Li2CO3 at 400...

  4. Synthesis and structural characterization of defect spinels in the lithium-manganese-oxide system

    CSIR Research Space (South Africa)

    Thackeray, MM

    1993-10-01

    Full Text Available Lithium-manganese-oxides prepared at moderate temperatures are under investigation as insertion electrodes for rechargeable lithium batteries. The structures of two defect-spinel compounds synthesized by the reaction of MnCO3 and Li2CO3 at 400°C...

  5. A method of eliminating the surface defect in low-temperature oxidation powder added UO2 pellet

    International Nuclear Information System (INIS)

    Yoo, H. S.; Lee, S. J.; Kim, J. I.; Jeon, K. R.; Kim, J. W.

    2002-01-01

    A study on methods to eliminate surface defect shown in low-temperature oxidation powder added UO 2 pellet has been performed. Powders oxidized at 350 .deg. C for 4 hrs were prepared and mixed with UO 2 powder after crushing them. After being sintered, surfaces of the pellet were inspected both visually and optically. A large number of defects were observed on the surface of the specimens in which low-temperature oxidation powders were directly mixed or master mixed with UO 2 powder while both specimens produced from mixed powders including milled oxidation powders and powders that were milled totally after mixing had clean surfaces. However, optical examination showed considerably large defected pores in the milled oxidation powder added pellet and it was confirmed that the inner defects can be eliminated completely only when milling the entire mixture on UO 2 and low-temperature oxidation powder, but not by crushing only oxidation powder

  6. Defect-mediated magnetism of transition metal doped zinc oxide thin films

    Science.gov (United States)

    Roberts, Bradley Kirk

    Magnetism in transition metal doped wide band-gap materials is of interest to further the fundamental science of materials and future spintronics applications. Large inter-dopant separations require mediation of ferromagnetism by some method; carrier-mediated mechanisms are typically applicable to dilute magnetic semiconductors with low Curie temperatures. Dilute magnetic oxides, commonly with poor conductivity and TC above room temperature, cannot be described within this theory. Recent experiment and theory developments suggest that ferromagnetic exchange in these materials can be mediated by defects. This research includes experimental results justifying and developing this approach. Thin films of Cr doped ZnO (band gap ˜3.3 eV) were deposited with several processing variations to enhance the effects of either 0-dimensional (vacancy, hydrogen-related defect) or two-dimensional defects (surface/interface) and thereby affect magnetism and conductivity. We observe surface magnetism in dielectric thin films of oxygen-saturated ZnO:Cr with spontaneous magnetic moment and conductance dropping approximately exponentially with increasing thickness. Uniform defect concentrations would not result in such magnetic ordering behavior indicating that magnetism is mediated either by surface defects or differing concentrations of point defects near the surface. Polarized neutron reflectivity profiling confirms a magnetically active region of ˜8 nm at the film surface. Hydrogen is notoriously present as a defect and carrier dopant in ZnO, and artificial introduction of hydrogen in dielectric ZnO:Cr films results in varying electronic and magnetic behavior. Free carriers introduced with hydrogen doping are not spin-polarized requiring an alternative explanation for ferromagnetism. We find from positron annihilation spectroscopy measurements that hydrogen doping increases the concentration of an altered VZn-related defect (a preliminary interpretation) throughout the film, which

  7. Tailoring defect structure and optical absorption of porous anodic aluminum oxide membranes

    International Nuclear Information System (INIS)

    Yan Hongdan; Lemmens, Peter; Wulferding, Dirk; Shi, Jianmin; Becker, Klaus Dieter; Lin, Chengtian; Lak, Aidin; Schilling, Meinhard

    2012-01-01

    Defects influence the optical and electronic properties of nanostructured materials that may be relevant for applications. In self-organized anodic aluminum oxide (AAO) templates we have investigated the effect of annealing, doping and nanoscale metal deposition. Optical absorption spectroscopy has been used as a sensitive probe for the defect density in AAO templates. The electronic spectra are found to be dominated by bands which originate from oxygen-deficient color centers (F + , F and F 2 ). In annealing studies, the integrated absorption of the bands changes non-monotonically with annealing temperature and annealing time. This demonstrates that the concentration of defects can be optimized to tailor the optical properties of the AAO. Metallic Au wires are deposited in the template to establish a plasmonic template or array. The investigations provide an interesting insight into the interplay of reactivity and diffusivity on nanoscales. - Highlights: ► Preparation of metal wire arrays in oxide templates with tailored plasmonic properties. ► Oxygen defects are characterized using optical absorption and fluorescence. ► Optical absorption spectra are assigned to energy levels of oxygen vacancies (color centers). ► Annealing and electrodeposition of Au wires minimize defects maintaining the morphology.

  8. Defect studies in copper-based p-type transparent conducting oxides

    Science.gov (United States)

    Ameena, Fnu

    Among other intrinsic open-volume defects, copper vacancy (VCu) has been theoretically identified as the major acceptor in p-type Cu-based semiconducting transparent oxides, which has potential as low-cost photovoltaic absorbers in semi-transparent solar cells. A series of positron annihilation experiments with pure Cu, Cu2O, and CuO presented strong presence of VCu and its complexes in the copper oxides. The lifetime data also showed that the density of VCu was becoming higher as the oxidation state of Cu increased which was consistent with the decrease in the formation energy of VCu. Doppler broadening measurements further indicated that electrons with low momentum made more contribution to the contributed as pure Cu oxidizes to copper oxides. The metastable defects are known to be generated in Cu2O upon illumination and it has been known to affect the performance of Cu2O-based hetero-junctions used in solar cells. The metastable effect was studied using positron annihilation lifetime spectroscopy and its data showed the change in the defect population upon light exposure and the minimal effect of light-induced electron density increase in the bulk of materials to the average lifetime of the positrons. The change in the defect population is concluded to be related to the dissociation and association of VCu -- V Cu complexes. For example, the shorter lifetime under light was ascribed to the annihilation with smaller size vacancies, which explains the dissociation of the complexes with light illumination. Doppler broadening of the annihilation was independent of light illumination, which suggested that the chemical nature of the defects remained without change upon their dissociation and association -- only the size distribution of copper vacancies varied. The delafossite metal oxides, CuMIIIO2 are emerging wide-bandgap p-type semiconductors. In this research, the formation energies of structural vacancies are calculated using Van Vechten cavity model as an attempt

  9. Intrinsic electronic defects and multiple-atom processes in the oxidic semiconductor Ga2O3

    Science.gov (United States)

    Schmeißer, Dieter; Henkel, Karsten

    2018-04-01

    We report on the electronic structure of gallium oxide (Ga2O3) single crystals as studied by resonant photoelectron spectroscopy (resPES). We identify intrinsic electronic defects that are formed by mixed-atomic valence states. We differentiate three coexisting defect states that differ in their electronic correlation energy and their spatial localization lengths. Their relative abundance is described by a fractional ionicity with covalent and ionic bonding contributions. For Ga2O3, our analyses of the resPES data enable us to derive two main aspects: first, experimental access is given to determine the ionicity based on the original concepts of Pauling and Phillips. Second, we report on multi-atomic energy loss processes in the Ga2p core level and X-ray absorption data. The two experimental findings can be explained consistently in the same context of mixed-atomic valence states and intrinsic electronic defects.

  10. Reduced coupling of oxidative phosphorylation in vivo precedes electron transport chain defects due to mild oxidative stress in mice.

    Directory of Open Access Journals (Sweden)

    Michael P Siegel

    Full Text Available Oxidative stress and mitochondrial function are at the core of many degenerative conditions. However, the interaction between oxidative stress and in vivo mitochondrial function is unclear. We used both pharmacological (2 week paraquat (PQ treatment of wild type mice and transgenic (mice lacking Cu, Zn-superoxide dismutase (SOD1(-/- models to test the effect of oxidative stress on in vivo mitochondrial function in skeletal muscle. Magnetic resonance and optical spectroscopy were used to measure mitochondrial ATP and oxygen fluxes and cell energetic state. In both models of oxidative stress, coupling of oxidative phosphorylation was significantly lower (lower P/O at rest in vivo in skeletal muscle and was dose-dependent in the PQ model. Despite this reduction in efficiency, in vivo mitochondrial phosphorylation capacity (ATPmax was maintained in both models, and ex vivo mitochondrial respiration in permeabilized muscle fibers was unchanged following PQ treatment. In association with the reduced P/O, PQ treatment led to a dose-dependent reduction in PCr/ATP ratio and increased phosphorylation of AMPK. These results indicate that oxidative stress uncouples oxidative phosphorylation in vivo and results in energetic stress in the absence of defects in the mitochondrial electron transport chain.

  11. Role of masking oxide on silicon in processes of defect generation at formation of SIMOX structures

    CERN Document Server

    Askinazi, A Y; Miloglyadova, L V

    2002-01-01

    One investigated into Si-SiO sub 2 structures formed by implantation of oxygen ions into silicon (SIMOX-technology) by means of techniques based on measuring of high-frequency volt-farad characteristics and by means of electroluminescence. One determined existence of electrically active centres and of luminescence centres in the formed oxide layer near boundary with silicon. One clarified the role SiO sub 2 masking layer in silicon in defect generation under formation of the masked oxide layer. One established dependence of concentration of electrically active and luminescence centres on thickness of masking layer

  12. On an aspect of kinetics both defects accumulation and gas absorption in an irradiated metals oxides

    International Nuclear Information System (INIS)

    Tuseev, T.; Polyakov, A.I.; Bitenbaev, M.I.

    2001-01-01

    In the work an analysis of experimental data during study both gases adsorption processes and radiation defects accumulation in irradiated (ultraviolet, gamma-, neutron-, alpha-particle- and proton radiation) in the oxides (SiO 2 , Al 2 O 3 , BeO, Se 2 O 3 , Dy 2 O 3 , La 2 O 3 , Er 2 O 3 ) is carried out. It is determined, that these processes are correlating with each other and equivalent kinetic equations for its description are proposed

  13. Band alignment and defects of the diamond zinc oxide heterojunction; Bandstruktur und Defekte der Diamant-Zinkoxid-Heterostruktur

    Energy Technology Data Exchange (ETDEWEB)

    Geithner, Peter

    2008-09-12

    Zinc oxide films were grown on diamond single crystals by rf sputtering of zinc oxide. The valence and conduction band offset was determined by photoelectron spectroscopy. A deep defect occurring in the zinc oxide films on diamond was characterized by cathodoluminescence spectroscopy. (orig.)

  14. Controlled Defects of Zinc Oxide Nanorods for Efficient Visible Light Photocatalytic Degradation of Phenol

    Directory of Open Access Journals (Sweden)

    Jamal Al-Sabahi

    2016-03-01

    Full Text Available Environmental pollution from human and industrial activities has received much attention as it adversely affects human health and bio-diversity. In this work we report efficient visible light photocatalytic degradation of phenol using supported zinc oxide (ZnO nanorods and explore the role of surface defects in ZnO on the visible light photocatalytic activity. ZnO nanorods were synthesized on glass substrates using a microwave-assisted hydrothermal process, while the surface defect states were controlled by annealing the nanorods at various temperatures and were characterized by photoluminescence and X-ray photoelectron spectroscopy. High performance liquid chromatography (HPLC was used for the evaluation of phenol photocatalytic degradation. ZnO nanorods with high surface defects exhibited maximum visible light photocatalytic activity, showing 50% degradation of 10 ppm phenol aqueous solution within 2.5 h, with a degradation rate almost four times higher than that of nanorods with lower surface defects. The mineralization process of phenol during degradation was also investigated, and it showed the evolution of different photocatalytic byproducts, such as benzoquinone, catechol, resorcinol and carboxylic acids, at different stages. The results from this study suggest that the presence of surface defects in ZnO nanorods is crucial for its efficient visible light photocatalytic activity, which is otherwise only active in the ultraviolet region.

  15. Effect of morphology and defect density on electron transfer of electrochemically reduced graphene oxide

    International Nuclear Information System (INIS)

    Zhang, Yan; Hao, Huilian; Wang, Linlin

    2016-01-01

    Highlights: • Different morphologies of ERGO on the surface of GCE were prepared via different methods. • The defect densities of ERGO were controlled by tuning the mass or concentration of GO. • A higher defect density of ERGO accelerates electron transfer rate. • ERGO with more exposed edge planes shows significantly higher electron transfer kinetics. • Both edge planes and defect density contribute to electron transfer of ERGO. - Abstract: Electrochemically reduced graphene oxide (ERGO) is widely used to construct electrochemical sensors. Understanding the electron transfer behavior of ERGO is essential for its electrode material applications. In this paper, different morphologies of ERGO were prepared via two different methods. Compared to ERGO/GCEs prepared by electrochemical reduction of pre-deposited GO, more exposed edge planes of ERGO are observed on the surface of ERGO-GCE that was constructed by electrophoretic deposition of GO. The defect densities of ERGO were controlled by tuning the mass or concentration of GO. The electron transfer kinetics (k"0) of GCE with different ERGOs was comparatively investigated. Owing to increased surface areas and decreased defect density, the k"0 values of ERGO/GCE initially increase and then decrease with incrementing of GO mass. When the morphology and surface real areas of ERGO-GCE are the same, an increased defect density induces an accelerated electron transfer rate. k"0 valuesof ERGO-GCEs are about 1 order of magnitude higher than those of ERGO/GCEs due to the difference in the amount of edge planes. This work demonstrates that both defect densities and edge planes of ERGO play crucial roles in electron transfer kinetics.

  16. Effect of morphology and defect density on electron transfer of electrochemically reduced graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan, E-mail: yanzhang@sues.edu.cn [School of Material Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Hao, Huilian, E-mail: huilian.hao@sues.edu.cn [School of Material Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Wang, Linlin, E-mail: wlinlin@mail.ustc.edu.cn [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China)

    2016-12-30

    Highlights: • Different morphologies of ERGO on the surface of GCE were prepared via different methods. • The defect densities of ERGO were controlled by tuning the mass or concentration of GO. • A higher defect density of ERGO accelerates electron transfer rate. • ERGO with more exposed edge planes shows significantly higher electron transfer kinetics. • Both edge planes and defect density contribute to electron transfer of ERGO. - Abstract: Electrochemically reduced graphene oxide (ERGO) is widely used to construct electrochemical sensors. Understanding the electron transfer behavior of ERGO is essential for its electrode material applications. In this paper, different morphologies of ERGO were prepared via two different methods. Compared to ERGO/GCEs prepared by electrochemical reduction of pre-deposited GO, more exposed edge planes of ERGO are observed on the surface of ERGO-GCE that was constructed by electrophoretic deposition of GO. The defect densities of ERGO were controlled by tuning the mass or concentration of GO. The electron transfer kinetics (k{sup 0}) of GCE with different ERGOs was comparatively investigated. Owing to increased surface areas and decreased defect density, the k{sup 0} values of ERGO/GCE initially increase and then decrease with incrementing of GO mass. When the morphology and surface real areas of ERGO-GCE are the same, an increased defect density induces an accelerated electron transfer rate. k{sup 0} valuesof ERGO-GCEs are about 1 order of magnitude higher than those of ERGO/GCEs due to the difference in the amount of edge planes. This work demonstrates that both defect densities and edge planes of ERGO play crucial roles in electron transfer kinetics.

  17. Defect engineering in 1D Ti-W oxide nanotube arrays and their correlated photoelectrochemical performance.

    Science.gov (United States)

    Abdelhafiz, Ali A; Ganzoury, Mohamed A; Amer, Ahmad W; Faiad, Azza A; Khalifa, Ahmed M; AlQaradawi, Siham Y; El-Sayed, Mostafa A; Alamgir, Faisal M; Allam, Nageh K

    2018-04-18

    Understanding the nature of interfacial defects of materials is a critical undertaking for the design of high-performance hybrid electrodes for photocatalysis applications. Theoretical and computational endeavors to achieve this have touched boundaries far ahead of their experimental counterparts. However, to achieve any industrial benefit out of such studies, experimental validation needs to be systematically undertaken. In this sense, we present herein experimental insights into the synergistic relationship between the lattice position and oxidation state of tungsten ions inside a TiO2 lattice, and the respective nature of the created defect states. Consequently, a roadmap to tune the defect states in anodically-fabricated, ultrathin-walled W-doped TiO2 nanotubes is proposed. Annealing the nanotubes in different gas streams enabled the engineering of defects in such structures, as confirmed by XRD and XPS measurements. While annealing under hydrogen stream resulted in the formation of abundant Wn+ (n < 6) ions at the interstitial sites of the TiO2 lattice, oxygen- and air-annealing induced W6+ ions at substitutional sites. EIS and Mott-Schottky analyses indicated the formation of deep-natured trap states in the hydrogen-annealed samples, and predominantly shallow donating defect states in the oxygen- and air-annealed samples. Consequently, the photocatalytic performance of the latter was significantly higher than those of the hydrogen-annealed counterparts. Upon increasing the W content, photoelectrochemical performance deteriorated due to the formation of WO3 crystallites that hindered charge transfer through the photoanode, as evident from the structural and chemical characterization. To this end, this study validates the previous theoretical predictions on the detrimental effect of interstitial W ions. In addition, it sheds light on the importance of defect states and their nature for tuning the photoelectrochemical performance of the investigated materials.

  18. Intrinsic point defects in zinc oxide. Modeling of structural, electronic, thermodynamic and kinetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Erhart, P.

    2006-07-01

    The present dissertation deals with the modeling of zinc oxide on the atomic scale employing both quantum mechanical as well as atomistic methods. The first part describes quantum mechanical calculations based on density functional theory of intrinsic point defects in ZnO. To begin with, the geometric and electronic structure of vacancies and oxygen interstitials is explored. In equilibrium oxygen interstitials are found to adopt dumbbell and split interstitial configurations in positive and negative charge states, respectively. Semi-empirical self-interaction corrections allow to improve the agreement between the experimental and the calculated band structure significantly; errors due to the limited size of the supercells can be corrected by employing finite-size scaling. The effect of both band structure corrections and finite-size scaling on defect formation enthalpies and transition levels is explored. Finally, transition paths and barriers for the migration of zinc as well as oxygen vacancies and interstitials are determined. The results allow to interpret diffusion experiments and provide a consistent basis for developing models for device simulation. In the second part an interatomic potential for zinc oxide is derived. To this end, the Pontifix computer code is developed which allows to fit analytic bond-order potentials. The code is subsequently employed to obtain interatomic potentials for Zn-O, Zn-Zn, and O-O interactions. To demonstrate the applicability of the potentials, simulations on defect production by ion irradiation are carried out. (orig.)

  19. Thermodynamic and kinetic modelling of fuel oxidation behaviour in operating defective fuel

    International Nuclear Information System (INIS)

    Lewis, B.J.; Thompson, W.T.; Akbari, F.; Thompson, D.M.; Thurgood, C.; Higgs, J.

    2004-01-01

    A theoretical treatment has been developed to predict the fuel oxidation behaviour in operating defective nuclear fuel elements. The equilibrium stoichiometry deviation in the hyper-stoichiometric fuel has been derived from thermodynamic considerations using a self-consistent set of thermodynamic properties for the U-O system, which emphasizes replication of solubilities and three-phase invariant conditions displayed in the U-O binary phase diagram. The kinetics model accounts for multi-phase transport including interstitial oxygen diffusion in the solid and gas-phase transport of hydrogen and steam in the fuel cracks. The fuel oxidation model is further coupled to a heat conduction model to account for the feedback effect of a reduced thermal conductivity in the hyper-stoichiometric fuel. A numerical solution has been developed using a finite-element technique with the FEMLAB software package. The model has been compared to available data from several in-reactor X-2 loop experiments with defective fuel conducted at the Chalk River Laboratories. The model has also been benchmarked against an O/U profile measurement for a spent defective fuel element discharged from a commercial reactor

  20. Dynamics of Defects and Dopants in Complex Systems: Si and Oxide Surfaces and Interfaces

    Science.gov (United States)

    Kirichenko, Taras; Yu, Decai; Banarjee, Sanjay; Hwang, Gyeong

    2004-10-01

    Fabrication of forthcoming nanometer scale electronic devices faces many difficulties including formation of extremely shallow and highly doped junctions. At present, ultra-low-energy ion implantation followed by high-temperature thermal annealing is most widely used to fabricate such ultra-shallow junctions. In the process, a great challenge lies in achieving precise control of redistribution and electrical activation of dopant impurities. Native defects (such as vacancies and interstitials) generated during implantation are known to be mainly responsible for the TED and also influence significantly the electrical activation/deactivation. Defect-dopant dynamics is rather well understood in crystalline Si and SiO2. However, little is known about their diffusion and annihilation (or precipitation) at the surfaces and interfaces, despite its growing importance in determining junction profiles as device dimensions get smaller. In this talk, we will present our density functional theory calculation results on the atomic and electronic structure and dynamical behavior of native defects and dopant-defect complexes in disordered/strained Si and oxide systems, such as i) clean and absorbent-modified Si(100) surface and subsurface layers, ii) amorphous-crystalline Si interfaces and iii) amorphous SiO2/Si interfaces. The fundamental understanding and data is essential in developing a comprehensive kinetic model for junction formation, which would contribute greatly in improving current process technologies.

  1. Defect physics vis-à-vis electrochemical performance in layered mixed-metal oxide cathode materials

    Science.gov (United States)

    Hoang, Khang; Johannes, Michelle

    Layered mixed-metal oxides with different compositions of (Ni,Co,Mn) [NCM] or (Ni,Co,Al) [NCA] have been used in commercial lithium-ion batteries. Yet their defect physics and chemistry is still not well understood, despite having important implications for the electrochemical performance. In this presentation, we report a hybrid density functional study of intrinsic point defects in the compositions LiNi1/3Co1/3Mn1/3O2 (NCM1/3) and LiNi1/3Co1/3Al1/3O2 (NCA1/3) which can also be regarded as model compounds for NCM and NCA. We will discuss defect landscapes in NCM1/3 and NCA1/3 under relevant synthesis conditions with a focus on the formation of metal antisite defects and its implications on the electrochemical properties and ultimately the design of NCM and NCA cathode materials.

  2. Tuning the reactivity of Ru nanoparticles by defect engineering of the reduced graphene oxide support

    KAUST Repository

    Liu, Xin

    2014-01-01

    We systematically investigated the electronic structure of Ru nanoparticles supported on various local structures on reduced graphene oxide (rGO) by first-principles-based calculations. We showed that Ru nanoparticles prefer to nucleate at these localized defect structures on rGO, which act as strong trapping sites for Ru nanoparticles and inhibit their aggregation. The binding of Ru nanoparticles to rGO, which is dependent on these local defect structures and correlates with the interfacial charge transfer, determines the electronic structure of the composites. Further study reveals that the performance of these composites against oxygen adsorption changes proportionally with the shift of the d-band center of the nanoparticles. The correlation between the defect structures on rGO and the reactivity of the composites suggests that controlled modification of the graphenic support by defect engineering would be an efficient way to fabricate new transition metal/rGO composites with high stability and desired reactivity. This journal is © the Partner Organisations 2014.

  3. Positron annihilation study of defects in electron-irradiated single crystal zinc oxide

    Science.gov (United States)

    To, C. K.; Yang, B.; Beling, C. D.; Fung, S.; Ling, C. C.; Gong, M.

    2011-01-01

    Pressurized melt grown zinc oxide (ZnO) single crystals purchased from Cermet Inc. were irradiated by 2MeV electrons with fluence of 6x1017cm-2. Isochronal annealing from 100°C-800°C was performed on the crystals under argon and air ambience. Variable Energy Doppler Broadening Spectroscopy (VEDBS) was carried out on both the as-grown and the irradiated samples at each annealing step. The migration, agglomeration and annealing of grown-in and irradiated-introduced defects were studied. It was observed that the grown-in vacancy-type defects concentration decreased at 300°C and 600 °C. For the irradiated sample annealed in argon, the positron trapping vacancy-type defect concentration decreased at 300°C and 600°C. Further annealing the as-grown and irradiated samples in argon increased the S parameter further. For the irradiated sample annealed in air, the vacancy-type defect concentration decreases at 300°C and 700°C.

  4. Positron annihilation study of defects in electron-irradiated single crystal zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    To, C K; Yang, B; Beling, C D; Fung, S; Ling, C C [Department of Physics, University of Hong Kong (Hong Kong); Gong, M, E-mail: sfung@hkucc.hku.h, E-mail: edwardto04@yahoo.com.h [Department of Physics, Sichuan University, Chengdu (China)

    2011-01-01

    Pressurized melt grown zinc oxide (ZnO) single crystals purchased from Cermet Inc. were irradiated by 2 MeV electrons with fluence of 6x10{sup 17}cm{sup -2}. Isochronal annealing from 100 deg. C - 800 deg. C was performed on the crystals under argon and air ambience. Variable Energy Doppler Broadening Spectroscopy (VEDBS) was carried out on both the as-grown and the irradiated samples at each annealing step. The migration, agglomeration and annealing of grown-in and irradiated-introduced defects were studied. It was observed that the grown-in vacancy-type defects concentration decreased at 300 deg. C and 600 deg. C. For the irradiated sample annealed in argon, the positron trapping vacancy-type defect concentration decreased at 300 deg. C and 600 deg. C. Further annealing the as-grown and irradiated samples in argon increased the S parameter further. For the irradiated sample annealed in air, the vacancy-type defect concentration decreases at 300 deg. C and 700 deg. C.

  5. Positron annihilation study of defects in electron-irradiated single crystal zinc oxide

    International Nuclear Information System (INIS)

    To, C K; Yang, B; Beling, C D; Fung, S; Ling, C C; Gong, M

    2011-01-01

    Pressurized melt grown zinc oxide (ZnO) single crystals purchased from Cermet Inc. were irradiated by 2 MeV electrons with fluence of 6x10 17 cm -2 . Isochronal annealing from 100 deg. C - 800 deg. C was performed on the crystals under argon and air ambience. Variable Energy Doppler Broadening Spectroscopy (VEDBS) was carried out on both the as-grown and the irradiated samples at each annealing step. The migration, agglomeration and annealing of grown-in and irradiated-introduced defects were studied. It was observed that the grown-in vacancy-type defects concentration decreased at 300 deg. C and 600 deg. C. For the irradiated sample annealed in argon, the positron trapping vacancy-type defect concentration decreased at 300 deg. C and 600 deg. C. Further annealing the as-grown and irradiated samples in argon increased the S parameter further. For the irradiated sample annealed in air, the vacancy-type defect concentration decreases at 300 deg. C and 700 deg. C.

  6. A polarity-induced defect mechanism for conductivity and magnetism at polar-nonpolar oxide interfaces.

    Science.gov (United States)

    Yu, Liping; Zunger, Alex

    2014-10-13

    The discovery of conductivity and magnetism at the polar-nonpolar interfaces of insulating nonmagnetic oxides such as LaAlO3 and SrTiO3 has raised prospects for attaining interfacial functionalities absent in the component materials. Yet, the microscopic origin of such emergent phenomena remains unclear, posing obstacles to design of improved functionalities. Here we present first principles calculations of electronic and defect properties of LaAlO3/SrTiO3 interfaces and reveal a unifying mechanism for the origins of both conductivity and magnetism. We demonstrate that the polar discontinuity across the interface triggers thermodynamically the spontaneous formation of certain defects that in turn cancel the polar field induced by the polar discontinuity. The ionization of the spontaneously formed surface oxygen vacancy defects leads to interface conductivity, whereas the unionized Ti-on-Al antisite defects lead to interface magnetism. The proposed mechanism suggests practical design principles for inducing and controlling both conductivity and magnetism at general polar-nonpolar interfaces.

  7. Anatase titanium dioxide nanoparticles in mice: evidence for induced structural and functional sperm defects after short-, but not long-, term exposure

    Directory of Open Access Journals (Sweden)

    Michelle A Smith

    2015-04-01

    Full Text Available Titanium dioxide (TiO 2 nanoparticles (TNPs are widely used commercially and exist in a variety of products. To determine if anatase TNPs (ATNPs in doses smaller than previously used reach the scrotum after entry in the body at a distant location and induce sperm defects, 100% ATNP (2.5 or 5 mg kg−1 body weight was administered intraperitoneally to adult males for three consecutive days, followed by sacrifice 1, 2, 3, or 5 weeks later (long- or 24, 48 or 120 h (short-term exposure. Transmission electron microscopy revealed the presence of ANTP in scrotal adipose tissues collected 120 h postinjection when cytokine evaluation showed an inflammatory response in epididymal tissues and fluid. At 120 h and up to 3 weeks postinjection, testicular histology revealed enlarged interstitial spaces. Significantly increased numbers of terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling-positive (apoptotic germ (P = 0.002 and interstitial space cells (P = 0.04 were detected in treated males. Caudal epididymal sperm from the short-term, but not a long-term, arm showed significantly (P < 0.001 increased frequencies of flagellar abnormalities, excess residual cytoplasm (ERC, and unreacted acrosomes in treated versus controls (dose-response relationship. A novel correlation between ERC and unreacted acrosomes was uncovered. At 120 h, there were significant decreases in hyperactivated motility (P < 0.001 and mitochondrial membrane potential (P < 0.05, and increased reactive oxygen species levels (P < 0.00001 in treated versus control sperm. These results indicate that at 4-8 days postinjection, ANTP induce structural and functional sperm defects associated with infertility, and DNA damage via oxidative stress. Sperm defects were transient as they were not detected 10 days to 5 weeks postinjection.

  8. Anatase titanium dioxide nanoparticles in mice: evidence for induced structural and functional sperm defects after short-, but not long-, term exposure

    Science.gov (United States)

    Smith, Michelle A; Michael, Rowan; Aravindan, Rolands G; Dash, Soma; Shah, Syed I; Galileo, Deni S; Martin-DeLeon, Patricia A

    2015-01-01

    Titanium dioxide (TiO2) nanoparticles (TNPs) are widely used commercially and exist in a variety of products. To determine if anatase TNPs (ATNPs) in doses smaller than previously used reach the scrotum after entry in the body at a distant location and induce sperm defects, 100% ATNP (2.5 or 5 mg kg−1 body weight) was administered intraperitoneally to adult males for three consecutive days, followed by sacrifice 1, 2, 3, or 5 weeks later (long-) or 24, 48 or 120 h (short-term exposure). Transmission electron microscopy revealed the presence of ANTP in scrotal adipose tissues collected 120 h postinjection when cytokine evaluation showed an inflammatory response in epididymal tissues and fluid. At 120 h and up to 3 weeks postinjection, testicular histology revealed enlarged interstitial spaces. Significantly increased numbers of terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling-positive (apoptotic) germ (P = 0.002) and interstitial space cells (P = 0.04) were detected in treated males. Caudal epididymal sperm from the short-term, but not a long-term, arm showed significantly (P < 0.001) increased frequencies of flagellar abnormalities, excess residual cytoplasm (ERC), and unreacted acrosomes in treated versus controls (dose-response relationship). A novel correlation between ERC and unreacted acrosomes was uncovered. At 120 h, there were significant decreases in hyperactivated motility (P < 0.001) and mitochondrial membrane potential (P < 0.05), and increased reactive oxygen species levels (P < 0.00001) in treated versus control sperm. These results indicate that at 4–8 days postinjection, ANTP induce structural and functional sperm defects associated with infertility, and DNA damage via oxidative stress. Sperm defects were transient as they were not detected 10 days to 5 weeks postinjection. PMID:25370207

  9. Point defects and irradiation in oxides: simulations at the atomic scale

    International Nuclear Information System (INIS)

    Crocombette, J.P.

    2005-11-01

    The author gives an overview of his research activity since 1995. This activity concerns research in materials science, and more particularly the ageing of oxides present in the nuclear industry, or more generally, the evolution of these materials under irradiation. The first part deals with the investigation of point defects, and more particularly of the structures and energies of these defects. The author discusses results obtained on uranium dioxide, on amorphous silica, and on the solution of oxygen in silver. The second part deals with irradiation-induced damages in crystalline matrices storing radioactive actinides, and more particularly with the effect of alpha disintegration decay nuclei which are the main sources of long term irradiation in these materials

  10. Electrochemical behavior of thin anodic oxide films on Zircaloy-4: Role of the mobile defects

    International Nuclear Information System (INIS)

    Salot, R.; Lefebvre-Joud, F.; Baroux, B.

    1996-01-01

    The first stages of the electrochemical oxidation of Zircaloy-4 are investigated using simple electrochemical tests and modeling the passive film modifications occurring as a result of contact with the electrolyte. Variations in electrode potential (open-circuit conditions) or current density (potentiodynamic scans) can be simply explained by a high field (F ∼ 10 6 V/cm) assisted passive film growth. Under open-circuit conditions, this field does not vary with exposure time (in the 2 h to 48 h range). The minimum electric field for the onset of high-field behavior is also evaluated and found smaller than the theoretical value which can be explained by a variation in the concentration of mobile defects throughout the film. Measurements of the electrode potential decay after a potentiodynamic scan confirm this model, allowing interpretation of the film modification as a combination of two separate phenomena: film growth under a high electric field and point defect annihilation

  11. Effect of cladding defect size on the oxidation of irradiated spent LWR [light-water reactor] fuel below 3690C

    International Nuclear Information System (INIS)

    Einziger, R.E.; Strain, R.V.

    1984-01-01

    Tests on spent fuel fragments and rod segments were conducted between 250 and 360 0 C to relate temperature, defect size, and fuel oxidation rate with time-to-cladding-splitting. Defect sizes from 760 μm diameter down to 8 μm, the size of an SCC type breach, were used. Above 283 0 C, the time-to-cladding-splitting was longer for the smaller defects. The enhancement of the incubation time by smaller defects steadily decreased with temperature and was not detected at 250 0 C. 18 refs., 10 figs., 4 tabs

  12. Electron-spin-resonance study of radiation-induced paramagnetic defects in oxides grown on (100) silicon substrates

    International Nuclear Information System (INIS)

    Kim, Y.Y.; Lenahan, P.M.

    1988-01-01

    We have used electron-spin resonance to investigate radiation-induced point defects in Si/SiO 2 structures with (100) silicon substrates. We find that the radiation-induced point defects are quite similar to defects generated in Si/SiO 2 structures grown on (111) silicon substrates. In both cases, an oxygen-deficient silicon center, the E' defect, appears to be responsible for trapped positive charge. In both cases trivalent silicon (P/sub b/ centers) defects are primarily responsible for radiation-induced interface states. In earlier electron-spin-resonance studies of unirradiated (100) substrate capacitors two types of P/sub b/ centers were observed; in oxides prepared in three different ways only one of these centers, the P/sub b/ 0 defect, is generated in large numbers by ionizing radiation

  13. A model for the formation of lattice defects at silicon oxide precipitates in silicon

    International Nuclear Information System (INIS)

    Vanhellemont, J.; Gryse, O. de; Clauws, P.

    2003-01-01

    The critical size of silicon oxide precipitates and the formation of lattice defects by the precipitates are discussed. An expression is derived allowing estimation of self-interstitial emission by spherical precipitates as well as strain build-up during precipitate growth. The predictions are compared with published experimental data. A model for stacking fault nucleation at oxide precipitates is developed based on strain and self-interstitial accumulation during the thermal history of the wafer. During a low-temperature treatment high levels of strain develop. During subsequent high-temperature treatment, excess strain energy in the precipitate is released by self-interstitial emission leading to favourable conditions for stacking fault nucleation

  14. Investigation of defects in In–Ga–Zn oxide thin film using electron spin resonance signals

    International Nuclear Information System (INIS)

    Nonaka, Yusuke; Kurosawa, Yoichi; Komatsu, Yoshihiro; Ishihara, Noritaka; Oota, Masashi; Nakashima, Motoki; Hirohashi, Takuya; Takahashi, Masahiro; Yamazaki, Shunpei; Obonai, Toshimitsu; Hosaka, Yasuharu; Koezuka, Junichi; Yamauchi, Jun

    2014-01-01

    In–Ga–Zn oxide (IGZO) is a next-generation semiconductor material seen as an alternative to silicon. Despite the importance of the controllability of characteristics and the reliability of devices, defects in IGZO have not been fully understood. We investigated defects in IGZO thin films using electron spin resonance (ESR) spectroscopy. In as-sputtered IGZO thin films, we observed an ESR signal which had a g-value of g = 2.010, and the signal was found to disappear under thermal treatment. Annealing in a reductive atmosphere, such as N 2 atmosphere, generated an ESR signal with g = 1.932 in IGZO thin films. The temperature dependence of the latter signal suggests that the signal is induced by delocalized unpaired electrons (i.e., conduction electrons). In fact, a comparison between the conductivity and ESR signal intensity revealed that the signal's intensity is related to the number of conduction electrons in the IGZO thin film. The signal's intensity did not increase with oxygen vacancy alone but also with increases in both oxygen vacancy and hydrogen concentration. In addition, first-principle calculation suggests that the conduction electrons in IGZO may be generated by defects that occur when hydrogen atoms are inserted into oxygen vacancies

  15. Investigation of defects in In–Ga–Zn oxide thin film using electron spin resonance signals

    Energy Technology Data Exchange (ETDEWEB)

    Nonaka, Yusuke; Kurosawa, Yoichi; Komatsu, Yoshihiro; Ishihara, Noritaka; Oota, Masashi; Nakashima, Motoki; Hirohashi, Takuya; Takahashi, Masahiro; Yamazaki, Shunpei [Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa 243-0036 (Japan); Obonai, Toshimitsu; Hosaka, Yasuharu; Koezuka, Junichi [Advanced Film Device, Inc., 161-2 Masuzuka, Tsuga-machi, Tochigi, Tochigi 328-0114 (Japan); Yamauchi, Jun [Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa 243-0036 (Japan); Emeritus Professor of Kyoto University, Oiwake-cho, Kitashirakawa, Kyoto 606-8502 (Japan)

    2014-04-28

    In–Ga–Zn oxide (IGZO) is a next-generation semiconductor material seen as an alternative to silicon. Despite the importance of the controllability of characteristics and the reliability of devices, defects in IGZO have not been fully understood. We investigated defects in IGZO thin films using electron spin resonance (ESR) spectroscopy. In as-sputtered IGZO thin films, we observed an ESR signal which had a g-value of g = 2.010, and the signal was found to disappear under thermal treatment. Annealing in a reductive atmosphere, such as N{sub 2} atmosphere, generated an ESR signal with g = 1.932 in IGZO thin films. The temperature dependence of the latter signal suggests that the signal is induced by delocalized unpaired electrons (i.e., conduction electrons). In fact, a comparison between the conductivity and ESR signal intensity revealed that the signal's intensity is related to the number of conduction electrons in the IGZO thin film. The signal's intensity did not increase with oxygen vacancy alone but also with increases in both oxygen vacancy and hydrogen concentration. In addition, first-principle calculation suggests that the conduction electrons in IGZO may be generated by defects that occur when hydrogen atoms are inserted into oxygen vacancies.

  16. Charged defects during alpha-irradiation of actinide oxides as revealed by Raman and luminescence spectroscopy

    International Nuclear Information System (INIS)

    Mohun, R.; Desgranges, L.; Léchelle, J.; Simon, P.; Guimbretière, G.; Canizarès, A.; Duval, F.; Jegou, C.; Magnin, M.; Clavier, N.; Dacheux, N.; Valot, C.; Vauchy, R.

    2016-01-01

    We have recently evidenced an original Raman signature of alpha irradiation-induced defects in UO 2 . In this study, we aim to determine whether the same signature also exists in different actinide oxides, namely ThO 2 and PuO 2 . Sintered UO 2 and ThO 2 were initially irradiated with 21 MeV He 2+ ions using a cyclotron device and were subjected to an in situ luminescence experiment followed by Raman analysis. In addition, a PuO 2 sample which had accumulated self-irradiation damage due to alpha particles was investigated only by Raman measurement. Results obtained for the initially white ThO 2 showed that a blue color appeared in the irradiated areas as well as luminescence signals during irradiation. However, Raman spectroscopic analysis showed the absence of Raman signature in ThO 2 . In contrast, the irradiated UO 2 and PuO 2 confirmed the presence of the Raman signature but no luminescence peaks were observed. The proposed mechanism involves electronic defects in ThO 2 , while a coupling between electronic defects and phonons is required to explain the Raman spectra for UO 2 and PuO 2 .

  17. SHOX gene defects and selected dysmorphic signs in patients of idiopathic short stature and Léri-Weill dyschondrosteosis.

    Science.gov (United States)

    Hirschfeldova, K; Solc, R; Baxova, A; Zapletalova, J; Kebrdlova, V; Gaillyova, R; Prasilova, S; Soukalova, J; Mihalova, R; Lnenicka, P; Florianova, M; Stekrova, J

    2012-01-10

    The aim of the study was to analyze frequency of SHOX gene defects and selected dysmorphic signs in patients of both idiopathic short stature (ISS) and Léri-Weill dyschondrosteosis (LWD), all derived from the Czech population. Overall, 98 subjects were analyzed in the study. Inclusion criteria were the presence of short stature (-2.0 SD), in combination with at least one of the selected dysmorphic signs for the ISS+ group; and the presence of Madelung deformity, without positive karyotyping for the LWD+ group. Each proband was analyzed by use of P018 MLPA kit, which covers SHOX and its regulatory sequences. Additionally, mutational analysis was done of the coding portions of the SHOX. Both extent and breakpoint localizations in the deletions/duplications found were quite variable. Some PAR1 rearrangements were detected, without obvious phenotypic association. In the ISS+ group, MLPA analysis detected four PAR1 deletions associated with a SHOX gene defect, PAR1 duplication with an ambiguous effect, and two SHOX mutations (13.7%). In the LWD+ group, MLPA analysis detected nine deletions in PAR1 region, with a deleterious effect on SHOX, first reported case of isolated SHOX enhancer duplication, and SHOX mutation (68.8%). In both ISS+ and LWD+ groups were positivity associated with a disproportionately short stature; in the ISS+ group, in combination with muscular hypertrophy. It seems that small PAR1 rearrangements might be quite frequent in the population. Our study suggests disproportionateness, especially in combination with muscular hypertrophy, as relevant indicators of ISS to be the effect of SHOX defect. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Effects of phosphorylatable short peptide-conjugated chitosan-mediated IL-1Ra and igf-1 gene transfer on articular cartilage defects in rabbits.

    Directory of Open Access Journals (Sweden)

    Ronglan Zhao

    Full Text Available Previously, we reported an improvement in the transfection efficiency of the plasmid DNA-chitosan (pDNA/CS complex by the utilization of phosphorylatable short peptide-conjugated chitosan (pSP-CS. In this study, we investigated the effects of pSP-CS-mediated gene transfection of interleukin-1 receptor antagonist protein (IL-1Ra combined with insulin-like growth factor-1 (IGF-1 in rabbit chondrocytes and in a rabbit model of cartilage defects. pBudCE4.1-IL-1Ra+igf-1, pBudCE4.1-IL-1Ra and pBudCE4.1-igf-1 were constructed and combined with pSP-CS to form pDNA/pSP-CS complexes. These complexes were transfected into rabbit primary chondrocytes or injected into the joint cavity. Seven weeks after treatment, all rabbits were sacrificed and analyzed. High levels of IL-1Ra and igf-1 expression were detected both in the cell culture supernatant and in the synovial fluid. In vitro, the transgenic complexes caused significant proliferation of chondrocytes, promotion of glycosaminoglycan (GAG and collagen II synthesis, and inhibition of chondrocyte apoptosis and nitric oxide (NO synthesis. In vivo, the exogenous genes resulted in increased collagen II synthesis and reduced NO and GAG concentrations in the synovial fluid; histological studies revealed that pDNA/pSP-CS treatment resulted in varying degrees of hyaline-like cartilage repair and Mankin score decrease. The co-expression of both genes produced greater effects than each single gene alone both in vitro and in vivo. The results suggest that pSP-CS is a good candidate for use in gene therapy for the treatment of cartilage defects and that igf-1 and IL-1Ra co-expression produces promising biologic effects on cartilage defects.

  19. The role of nitric oxide in muscle fibers with oxidative phosphorylation defects

    International Nuclear Information System (INIS)

    Tengan, Celia H.; Kiyomoto, Beatriz H.; Godinho, Rosely O.; Gamba, Juliana; Neves, Afonso C.; Schmidt, Beny; Oliveira, Acary S.B.; Gabbai, Alberto A.

    2007-01-01

    NO has been pointed as an important player in the control of mitochondrial respiration, especially because of its inhibitory effect on cytochrome c oxidase (COX). However, all the events involved in this control are still not completely elucidated. We demonstrate compartmentalized abnormalities on nitric oxide synthase (NOS) activity on muscle biopsies of patients with mitochondrial diseases. NOS activity was reduced in the sarcoplasmic compartment in COX deficient fibers, whereas increased activity was found in the sarcolemma of fibers with mitochondrial proliferation. We observed increased expression of neuronal NOS (nNOS) in patients and a correlation between nNOS expression and mitochondrial content. Treatment of skeletal muscle culture with an NO donor induced an increase in mitochondrial content. Our results indicate specific roles of NO in compensatory mechanisms of muscle fibers with mitochondrial deficiency and suggest the participation of nNOS in the signaling process of mitochondrial proliferation in human skeletal muscle

  20. A short synthesis-stuttgart of (S)-pyrrolam A via domino oxidation-witting reaction

    Digital Repository Service at National Institute of Oceanography (India)

    Majik, M.S.; Shet, J.; Tilve, S.G.; Parameswaran, P.S.

    A short synthesis of (S)-pyrrolam A starting from readily available N-(benzyloxycarbonyl)-L prolinol is described that makes use of a domino primary alcohol oxidation-Witting reaction as the key step...

  1. Study of defects and vacancies in structural properties of Mn, co-doped oxides: ZnO

    Science.gov (United States)

    Kumar, Harish; Kaushik, A.; Alvi, P. A.; Dalela, B.; Dalela, S.

    2018-05-01

    The paper deals with the Structural properties on Mn, Co doped oxides ZnO samples using XRD, Positron Annihilation Lifetime (PAL) Spectra and Raman Spectra. The Mn, Co doped ZnO samples crystallize in a wurtzite structure without any impurity phases in XRD Spectra. The defect state of these samples has been investigated by using positron annihilation lifetime (PAL) spectroscopy technique in which all the relevant lifetime parameters are measured for all the spectra. The results are explained in the direction of doping concentration in these samples in terms of defects structure on Zn lattice site VZn and oxygen defects Vo.

  2. Defect modelling

    International Nuclear Information System (INIS)

    Norgett, M.J.

    1980-01-01

    Calculations, drawing principally on developments at AERE Harwell, of the relaxation about lattice defects are reviewed with emphasis on the techniques required for such calculations. The principles of defect modelling are outlined and various programs developed for defect simulations are discussed. Particular calculations for metals, ionic crystals and oxides, are considered. (UK)

  3. Defects influence on short circuit current density in p-i-n silicon solar cell

    International Nuclear Information System (INIS)

    Wagah F Mohamad; Alhan M Mustafa

    2006-01-01

    The admittance analysis method has been used to calculate the collection efficiency and the short circuit current density in a-Si:H p-i-n solar cell, as a function of the thickness of i-layer. Its is evident that the results of the short circuit current can be used to determine the optimal thickness of the i-layer of a cell, and it will be more accurate in comparison with the previous studies using a constant generation rate or an empirical exponential function for the generation of charge carriers throughout the i-layer

  4. First-principles study on oxidation effects in uranium oxides and high-pressure high-temperature behavior of point defects in uranium dioxide

    Science.gov (United States)

    Geng, Hua Y.; Song, Hong X.; Jin, K.; Xiang, S. K.; Wu, Q.

    2011-11-01

    Formation Gibbs free energy of point defects and oxygen clusters in uranium dioxide at high-pressure high-temperature conditions are calculated from first principles, using the LSDA+U approach for the electronic structure and the Debye model for the lattice vibrations. The phonon contribution on Frenkel pairs is found to be notable, whereas it is negligible for the Schottky defect. Hydrostatic compression changes the formation energies drastically, making defect concentrations depend more sensitively on pressure. Calculations show that, if no oxygen clusters are considered, uranium vacancy becomes predominant in overstoichiometric UO2 with the aid of the contribution from lattice vibrations, while compression favors oxygen defects and suppresses uranium vacancy greatly. At ambient pressure, however, the experimental observation of predominant oxygen defects in this regime can be reproduced only in a form of cuboctahedral clusters, underlining the importance of defect clustering in UO2+x. Making use of the point defect model, an equation of state for nonstoichiometric oxides is established, which is then applied to describe the shock Hugoniot of UO2+x. Furthermore, the oxidization and compression behavior of uranium monoxide, triuranium octoxide, uranium trioxide, and a series of defective UO2 at 0 K are investigated. The evolution of mechanical properties and electronic structures with an increase of the oxidation degree are analyzed, revealing the transition of the ground state of uranium oxides from metallic to Mott insulator and then to charge-transfer insulator due to the interplay of strongly correlated effects of 5f orbitals and the shift of electrons from uranium to oxygen atoms.

  5. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Chey, Chan Oeurn; Pozina, Galia; Willander, Magnus; Nur, Omer [Department of Science and Technology (ITN), Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden); Liu, Xianjie; Khranovskyy, Volodymyr [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-583 81 Linköping (Sweden)

    2015-08-15

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  6. The comparison of gamma-radiation and electrical stress influences on oxide and interface defects in power VDMOSFET

    Directory of Open Access Journals (Sweden)

    Đorić-Veljković Snežana M.

    2013-01-01

    Full Text Available The behaviour of oxide and interface defects in n-channel power vertical double-diffused metal-oxide-semiconductor field-effect transistors, firstly degraded by the gamma-irradiation and electric field and subsequently recovered and annealed, is presented. By analyzing the transfer characteristic shifts, the changes of threshold voltage and underlying changes of gate oxide and interface trap densities during the stress (recovery, annealing of investigated devices, it is shown that these two types of stress influence differently on the gate oxide and the SiO2-Si interface. [Projekat Ministarstva nauke Republike Srbije, br. OI171026

  7. Ultra-thin silicon oxide layers on crystalline silicon wafers: Comparison of advanced oxidation techniques with respect to chemically abrupt SiO{sub 2}/Si interfaces with low defect densities

    Energy Technology Data Exchange (ETDEWEB)

    Stegemann, Bert, E-mail: bert.stegemann@htw-berlin.de [HTW Berlin - University of Applied Sciences, 12459 Berlin (Germany); Gad, Karim M. [University of Freiburg, Department of Microsystems Engineering - IMTEK, 79110 Freiburg (Germany); Balamou, Patrice [HTW Berlin - University of Applied Sciences, 12459 Berlin (Germany); Helmholtz Center Berlin for Materials and Energy (HZB), 12489 Berlin (Germany); Sixtensson, Daniel [Helmholtz Center Berlin for Materials and Energy (HZB), 12489 Berlin (Germany); Vössing, Daniel; Kasemann, Martin [University of Freiburg, Department of Microsystems Engineering - IMTEK, 79110 Freiburg (Germany); Angermann, Heike [Helmholtz Center Berlin for Materials and Energy (HZB), 12489 Berlin (Germany)

    2017-02-15

    Highlights: • Fabrication of ultrathin SiO{sub 2} tunnel layers on c-Si. • Correlation of electronic and chemical SiO{sub 2}/Si interface properties revealed by XPS/SPV. • Chemically abrupt SiO{sub 2}/Si interfaces generate less interface defect states considerable. - Abstract: Six advanced oxidation techniques were analyzed, evaluated and compared with respect to the preparation of high-quality ultra-thin oxide layers on crystalline silicon. The resulting electronic and chemical SiO{sub 2}/Si interface properties were determined by a combined x-ray photoemission (XPS) and surface photovoltage (SPV) investigation. Depending on the oxidation technique, chemically abrupt SiO{sub 2}/Si interfaces with low densities of interface states were fabricated on c-Si either at low temperatures, at short times, or in wet-chemical environment, resulting in each case in excellent interface passivation. Moreover, the beneficial effect of a subsequent forming gas annealing (FGA) step for the passivation of the SiO{sub 2}/Si interface of ultra-thin oxide layers has been proven. Chemically abrupt SiO{sub 2}/Si interfaces have been shown to generate less interface defect states.

  8. Visual short-term store can compensate for a defective phonological short-term store in patients with apraxia of speech.

    Science.gov (United States)

    Silveri, Maria Caterina; Baldonero, Eleonora

    2013-11-01

    The aim of the study was to investigate whether, within the phonological short-term memory (STM) system, speech articulation disorders primarily due to cortical damage are associated with deficits in the phonological recoding of visual-verbal material, and whether the visual short-term store (STS) can compensate for inefficient access to the phonological STS, as suggested in previous reports. Two patients (AE and TM) with apraxia of speech due to atrophic cerebral damage were administered a battery of tasks devised to explore the organization of the phonological STM. AE's span was normal and TM's span was markedly reduced. Phonological similarity and word-length effects: Both patients showed the effects in visual presentation; the effect was less evident in verbal presentation. This suggests a phonological STS disorder and preserved rehearsal/phonological recoding, consistently with involvement of the left parietal regions, which was documented by the MRI in both patients. Unexpectedly, TM had a longer span for similar than for dissimilar words in visually presented stimuli. Silent phonology (on written material): At variance with controls, stress assignment improved during unattended speech both in AE and TM, while in both patients and controls a detrimental effect of unattended speech was documented in the initial sound task. To account for this unusual pattern of results, we hypothesized that whenever possible, AE and TM adopt the strategy that takes advantage of the visual STM store to compensate for a defective phonological STS. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  9. Gravitational wave signals from short-lived topological defects in the MSSM

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, Ayuki [Kavli IPMU (WPI), UTIAS, The University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); Department of Physics and Astronomy, University of California,Riverside, CA, 92507 (United States); Yamada, Masaki [Kavli IPMU (WPI), UTIAS, The University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); ICRR, The University of Tokyo,Kashiwa, Chiba 277-8582 (Japan)

    2015-10-09

    Supersymmetric theories, including the minimal supersymmetric standard model, usually contain many scalar fields whose potentials are absent in the exact supersymmetric limit and within the renormalizable level. Since their potentials are vulnerable to the finite energy density of the Universe through supergravity effects, these flat directions have nontrivial dynamics in the early Universe. Recently, we have pointed out that a flat direction may have a positive Hubble induced mass term during inflation whereas a negative one after inflation. In this case, the flat direction stays at the origin of the potential during inflation and then obtain a large vacuum expectation value after inflation. After that, when the Hubble parameter decreases down to the mass of the flat direction, it starts to oscillate around the origin of the potential. In this paper, we investigate the dynamics of the flat direction with and without higher dimensional superpotentials and show that topological defects, such as cosmic strings and domain walls, form at the end of inflation and disappear at the beginning of oscillation of the flat direction. We numerically calculate their gravitational signals and find that the observation of gravitational signals would give us information of supersymmetric scale, the reheating temperature of the Universe, and higher dimensional operators.

  10. Gravitational wave signals from short-lived topological defects in the MSSM

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, Ayuki; Yamada, Masaki, E-mail: ayuki.kamada@ucr.edu, E-mail: yamadam@icrr.u-tokyo.ac.jp [Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)

    2015-10-01

    Supersymmetric theories, including the minimal supersymmetric standard model, usually contain many scalar fields whose potentials are absent in the exact supersymmetric limit and within the renormalizable level. Since their potentials are vulnerable to the finite energy density of the Universe through supergravity effects, these flat directions have nontrivial dynamics in the early Universe. Recently, we have pointed out that a flat direction may have a positive Hubble induced mass term during inflation whereas a negative one after inflation. In this case, the flat direction stays at the origin of the potential during inflation and then obtain a large vacuum expectation value after inflation. After that, when the Hubble parameter decreases down to the mass of the flat direction, it starts to oscillate around the origin of the potential. In this paper, we investigate the dynamics of the flat direction with and without higher dimensional superpotentials and show that topological defects, such as cosmic strings and domain walls, form at the end of inflation and disappear at the beginning of oscillation of the flat direction. We numerically calculate their gravitational signals and find that the observation of gravitational signals would give us information of supersymmetric scale, the reheating temperature of the Universe, and higher dimensional operators.

  11. Irradiation temperature dependence of production efficiency of lattice defects in some neutron-irradiated oxides

    International Nuclear Information System (INIS)

    Okada, Moritami; Atobe, Kozo; Nakagawa, Masuo

    2004-01-01

    Temperature dependence of production efficiency of irradiation-induced defects in neutron-irradiated oxides has been investigated. Some oxide single crystals, MgO, α-Al 2 O 3 (sapphire) and TiO 2 (rutile), were irradiated at several controlled temperatures, 10, 20, 50, 100, 150 and 200 K, using the low-temperature irradiation facility of Kyoto University Reactor (KUR-LTL), and at ambient temperature (∼370 K) in the same facility. Irradiation temperature dependence of production efficiency of a 1 μm band in TiO 2 differs greatly from that of anion vacancy (F-type centers) in MgO and α-Al 2 O 3 . Results for MgO and α-Al 2 O 3 show steep negative gradients from 10 to 370 K, whereas that for TiO 2 includes a valley between 40 and 60 K and a hump at about 130 K, and then disappear at about 200 K. In MgO and α-Al 2 O 3 , this behavior can be explained by the recombination of Frenkel pairs, which is activated at higher temperature. In TiO 2 , in addition to the recombination mechanism, a covalent bonding property is thought to be exerted strong influence, and it is suggested that a disappearance of the 1 μm band at above 200 K is due to the recombination process of Frenkel pairs which is caused by the irradiation-induced crystallization

  12. Application of the integral method to modelling the oxidation of defected fuel elements

    International Nuclear Information System (INIS)

    Kolar, M.

    1995-06-01

    The starting point for this report is the discrepancy reported in previous work between the reaction-diffusion calculations and the CEX-1 experiment, which involves storage of defected fuel elements in air at 150 deg C. This discrepancy is considerably diminished here by a more critical choice of theoretical parameters, and by taking into account the fact that different CEX-1 fuel elements were oxidized at very different rates and that the fuel element used previously for comparison with theoretical calculations actually underwent two limited-oxygen-supply cycles. Much better agreement is obtained here between the theory and the third, unlimited-air, storage period of the CEX-1 experiment. The approximate integral method is used extensively for the solution of the one-dimensional diffusion moving-boundary problems that may describe various storage periods of the CEX-1 experiment. In some cases it is easy to extend this method to arbitrary precision by using higher moments of the diffusion equation. Using this method, the validity of quasi-steady-state approximation is verified. Diffusion-controlled oxidation is also studied. In this case, for the unlimited oxygen supply, the integral method leads to an exact analytical solution for linear geometry, and to a good analytical approximation of the solution for the spherically symmetric geometry. These solutions may have some application in the analysis of experiments on the oxidation of small UO 2 fragments or powders when the individual UO 2 grains may be considered to be approximately spherical. (author). 23 refs., 5 tabs., 11 figs

  13. Persistent short-term memory defects following sleep deprivation in a drosophila model of Parkinson disease.

    Science.gov (United States)

    Seugnet, Laurent; Galvin, James E; Suzuki, Yasuko; Gottschalk, Laura; Shaw, Paul J

    2009-08-01

    Parkinson disease (PD) is the second most common neurodegenerative disorder in the United States. It is associated with motor deficits, sleep disturbances, and cognitive impairment. The pathology associated with PD and the effects of sleep deprivation impinge, in part, upon common molecular pathways suggesting that sleep loss may be particularly deleterious to the degenerating brain. Thus we investigated the long-term consequences of sleep deprivation on shortterm memory using a Drosophila model of Parkinson disease. Transgenic strains of Drosophila melanogaster. Using the GAL4-UAS system, human alpha-synuclein was expressed throughout the nervous system of adult flies. Alpha-synuclein expressing flies (alpha S flies) and the corresponding genetic background controls were sleep deprived for 12 h at age 16 days and allowed to recover undisturbed for at least 3 days. Short-term memory was evaluated using aversive phototaxis suppression. Dopaminergic systems were assessed using mRNA profiling and immunohistochemistry. MEASURMENTS AND RESULTS: When sleep deprived at an intermediate stage of the pathology, alpha S flies showed persistent short-term memory deficits that lasted > or = 3 days. Cognitive deficits were not observed in younger alpha S flies nor in genetic background controls. Long-term impairments were not associated with accelerated loss of dopaminergic neurons. However mRNA expression of the dopamine receptors dDA1 and DAMB were significantly increased in sleep deprived alpha S flies. Blocking D1-like receptors during sleep deprivation prevented persistent shortterm memory deficits. Importantly, feeding flies the polyphenolic compound curcumin blocked long-term learning deficits. These data emphasize the importance of sleep in a degenerating/reorganizing brain and shows that pathological processes induced by sleep deprivation can be dissected at the molecular and cellular level using Drosophila genetics.

  14. Role of Defects and Adsorbed Water Film in Influencing the Electrical, Optical and Catalytic Properties of Transition Metal Oxides

    Science.gov (United States)

    Wang, Qi

    Transition metal oxides (TMOs) constitute a large group of materials that exhibit a wide range of optical, electrical, electrochemical, dielectric and catalytic properties, and thus making them highly regarded as promising materials for a variety of applications in next generation electronic, optoelectronic, catalytic, photonic, energy storage and energy conversion devices. Some of the unique properties of TMOs are their strong electron-electron correlations that exists between the valence electrons of narrow d- or f-shells and their ability to exist in variety of oxidation states. This gives TMOs an enormous range of fascinating electronic and other physical properties. Many of these remarkable properties of TMOs arises from the complex surface charge transfer processes at the oxide surface/electrochemical redox species interface and non-stoichiometry due to the presence of lattice vacancies that may cause significant perturbation to the electronic structure of the material. Stoichiometry, oxidation state of the metal center and lattice vacancy defects all play important roles in affecting the physical properties, electronic structures, device behavior and other functional properties of TMOs. However, the underlying relationships between them is not clearly known. For instance, the exchange of electrons between adsorbates and defects can lead to the passivation of existing defect states or formation of new defects, both of which affect defect equilibria, and consequently, functional properties. In depth understanding of the role of lattice defects on the electrical, catalytic and optical properties of TMOs is central to further expansion of the technological applications of TMO based devices. The focus of this work is to elucidate the interactions of vacancy defects with various electrochemical adsorbates in TMOs. The ability to directly probe the interactions of vacancy defects with gas and liquid phase species under in-operando conditions is highly desirable to

  15. Study on the intrinsic defects in tin oxide with first-principles method

    Science.gov (United States)

    Sun, Yu; Liu, Tingyu; Chang, Qiuxiang; Ma, Changmin

    2018-04-01

    First-principles and thermodynamic methods are used to study the contribution of vibrational entropy to defect formation energy and the stability of the intrinsic point defects in SnO2 crystal. According to thermodynamic calculation results, the contribution of vibrational entropy to defect formation energy is significant and should not be neglected, especially at high temperatures. The calculated results indicate that the oxygen vacancy is the major point defect in undoped SnO2 crystal, which has a higher concentration than that of the other point defect. The property of negative-U is put forward in SnO2 crystal. In order to determine the most stable defects much clearer under different conditions, the most stable intrinsic defect as a function of Fermi level, oxygen partial pressure and temperature are described in the three-dimensional defect formation enthalpy diagrams. The diagram visually provides the most stable point defects under different conditions.

  16. Evaluation of endogenous nitric oxide synthesis in congenital urea cycle enzyme defects.

    Science.gov (United States)

    Nagasaka, Hironori; Tsukahara, Hirokazu; Yorifuji, Tohru; Miida, Takashi; Murayama, Kei; Tsuruoka, Tomoko; Takatani, Tomozumi; Kanazawa, Masaki; Kobayashi, Kunihiko; Okano, Yoshiyuki; Takayanagi, Masaki

    2009-03-01

    Nitric oxide (NO) is synthesized from arginine and O(2) by nitric oxide synthase (NOS). Citrulline, which is formed as a by-product of the NOS reaction, can be recycled to arginine by the 2 enzymes acting in the urea cycle: argininosuccinate synthetase (ASS) and argininosuccinate lyase (ASL). Although the complete urea cycle is expressed only in the liver, ASS and ASL are expressed in other organs including the kidney and vascular endothelium. To examine possible alterations of the NO pathway in urea cycle defects, we measured plasma concentrations of arginine and citrulline and serum concentrations of nitrite/nitrate (NOx(-), stable NO metabolites) and asymmetric dimethylarginine (ADMA, an endogenous NOS inhibitor) in patients with congenital urea cycle disorders of 3 types: ornithine transcarbamylase (OTC) deficiency, ASS deficiency, and ASL deficiency. All were receiving oral arginine replacement at the time of this study. The same parameters were also measured in healthy subjects, who participated as controls. The OTC-deficient patients had significantly high NOx(-) and nonsignificantly high ADMA concentrations. Their NOx(-) was significantly positively correlated with arginine. The ASS-deficient patients had significantly low NOx(-) and significantly high ADMA concentrations. The ASL-deficient patients had normal NOx(-) and nonsignificantly high ADMA concentrations. In ASS-deficient and ASL-deficient patients, the NOx(-) was significantly inversely correlated with citrulline. These results suggest that NO synthesis is enhanced in OTC-deficient patients while receiving arginine but that NO synthesis remains low in ASS-deficient patients despite receiving arginine. They also suggest that endogenous NO synthesis is negatively affected by citrulline and ADMA in ASS-deficient and ASL-deficient patients. Although the molecular mechanisms remain poorly understood, we infer that the NO pathway might play a role in the pathophysiology related to congenital urea cycle

  17. Irradiation temperature dependence of production efficiency of lattice defects in some neutron-irradiated oxides

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Moritami [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 5900494 (Japan)]. E-mail: okada@rri.kyoto-u.ac.jp; Atobe, Kozo [Faculty of Science, Naruto University of Education, Naruto, Tokushima 7728502 (Japan); Nakagawa, Masuo [Faculty of Education, Kagawa University, Takamatsu, Kagawa 7608522 (Japan)

    2004-11-01

    Temperature dependence of production efficiency of irradiation-induced defects in neutron-irradiated oxides has been investigated. Some oxide single crystals, MgO, {alpha}-Al{sub 2}O{sub 3} (sapphire) and TiO{sub 2} (rutile), were irradiated at several controlled temperatures, 10, 20, 50, 100, 150 and 200 K, using the low-temperature irradiation facility of Kyoto University Reactor (KUR-LTL), and at ambient temperature ({approx}370 K) in the same facility. Irradiation temperature dependence of production efficiency of a 1 {mu}m band in TiO{sub 2} differs greatly from that of anion vacancy (F-type centers) in MgO and {alpha}-Al{sub 2}O{sub 3}. Results for MgO and {alpha}-Al{sub 2}O{sub 3} show steep negative gradients from 10 to 370 K, whereas that for TiO{sub 2} includes a valley between 40 and 60 K and a hump at about 130 K, and then disappear at about 200 K. In MgO and {alpha}-Al{sub 2}O{sub 3}, this behavior can be explained by the recombination of Frenkel pairs, which is activated at higher temperature. In TiO{sub 2}, in addition to the recombination mechanism, a covalent bonding property is thought to be exerted strong influence, and it is suggested that a disappearance of the 1 {mu}m band at above 200 K is due to the recombination process of Frenkel pairs which is caused by the irradiation-induced crystallization.

  18. Evaluation of oxidative status in short-term exercises of adolescent athletes

    OpenAIRE

    K Karacabey; A Atas; D Zeyrek; A Cakmak; R Kurkcu; F Yamaner

    2010-01-01

    The aim of the study was to evaluate the effects of short-term exercise on total antioxidant status (TAS), lipid hydroperoxide (LOOHs), total oxidative status (TOS) and oxidative stress index (OSI) in adolescent athletes. A total of 62 adolescent participated in the study. Athletes were trained regularly 3 days a week for 2 hours. All subjects followed a circuit exercise program. Blood samples were collected just before and immediately after the exercise program. Antioxidant status was evalu...

  19. Evaluation of oxidative status in short-term exercises of adolescent athletes

    Directory of Open Access Journals (Sweden)

    K Karacabey

    2010-09-01

    Full Text Available The aim of the study was to evaluate the effects of short-term exercise on total antioxidant status (TAS, lipid hydroperoxide (LOOHs, total oxidative status (TOS and oxidative stress index (OSI in adolescent athletes. A total of 62 adolescent participated in the study. Athletes were trained regularly 3 days a week for 2 hours. All subjects followed a circuit exercise program. Blood samples were collected just before and immediately after the exercise program. Antioxidant status was evaluated by measuring the TAS level in the plasma. Oxidative status was evaluated by measuring the total peroxide level. The percentage ratio of TAS to total peroxide level was accepted as the OSI. Plasma triglyceride, total cholesterol, LDL, HDL and VLDL were measured by automated chemical analyzer using commercially available kits.There was a significant increase in TOS (p<0.05 and OSI (p<0.01 levels and a significant decrease in TAS levels (p<0.01 compared to the resting state. There were no significant changes in LOOHs levels before and after the short-term exercise. After short-term exercise, the balance between oxidative stress and antioxidant status moves towards oxidative stress as a result of increasing oxidants and decreasing antioxidants.

  20. SHI induced defects in chemically synthesized graphene oxide for hydrogen storage applications

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Preetam K., E-mail: preetam.nano@gmail.com; Sharma, Vinay; Rajaura, Rajveer Singh; Singh, M. [Department of Physics, University of Rajasthan, Jaipur-302004, India. (India); Srivastava, Subodh; Vijay, Y. K. [Department of Physics, University of Rajasthan, Jaipur-302004, India. (India); Department of Physics, Vivekananda Global University, Jaipur-303012, India. (India); Sharma, S. S. [Department of Physics, Govt. Women Engineering College, Ajmer-305002, India. (India)

    2016-05-06

    Graphene, due to its unique properties arising from the single carbon layer, is a potential candidate for applications in a variety of fields including sensors, photovoltaics and energy storage. The atomic structure and morphology of the carbon nanomaterials especially graphene can be tailored by energetic ionic irradiation. As graphene sheet is very stable, the surface have less reactivity as compared to the edges of the sheets. By surface modification with energetic ion-beams additional dangling bonds can be formed to enhance the surface activity of the graphene film which could be exploited in a variety of applications. In the present work, graphene oxide was synthesized by improved Hummers’ Method. The irradiation was done with Ag{sup +} ions carrying energy 100 MeV with the fluence of 3×10{sup 13}. Raman spectrum of graphene irradiated by Ag{sup +} beam shows additional disordered peaks of D´ and D+G bands. There is also a decrease in the intensity of D band. AFM images depict the increase in the surface roughness of the films. This can be attributed to the increase in the defects in the flakes and intermixing of adjacent layers by irradiation.

  1. Fuel cracking in relation to fuel oxidation in support of an out-reactor instrumented defected fuel experiment

    Energy Technology Data Exchange (ETDEWEB)

    Quastel, A.; Thiriet, C. [Atomic Energy of Canada Limited, Chalk River, ON (Canada); Lewis, B., E-mail: brent.lewis@uoit.ca [Univ. of Ontario Inst. of Tech., Oshawa, ON (Canada); Corcoran, E., E-mail: emily.corcoran@rmc.ca [Royal Military College of Canada, Kingston, ON (Canada)

    2014-07-01

    An experimental program funded by the CANDU Owners Group (COG) is studying an out-reactor instrumented defected fuel experiment in Stern Laboratories (Hamilton, Ontario) with guidance from Atomic Energy of Canada Limited (AECL). The objective of this test is to provide experimental data for validation of a mechanistic fuel oxidation model. In this experiment a defected fuel element with UO{sub 2} pellets will be internally heated with an electrical heater element, causing the fuel to crack. By defecting the sheath in-situ the fuel will be exposed to light water coolant near normal reactor operating conditions (pressure 10 MPa and temperature 265-310{sup o}C) causing fuel oxidation, especially near the hotter regions of the fuel in the cracks. The fuel thermal conductivity will change, resulting in a change in the temperature distribution of the fuel element. This paper provides 2D r-θ plane strain solid mechanics models to simulate fuel thermal expansion, where conditions for fuel crack propagation are investigated with the thermal J integral to predict fuel crack stress intensity factors. Finally since fuel crack geometry can affect fuel oxidation this paper shows that the solid mechanics model with pre-set radial cracks can be coupled to a 2D r-θ fuel oxidation model. (author)

  2. Direct observation of short-circuit diffusion during the formation of a single cupric oxide nanowire

    International Nuclear Information System (INIS)

    Cheng, C-L; Ma, Y-R; Chou, M H; Huang, C Y; Yeh, V; Wu, S Y

    2007-01-01

    Short-circuit diffusion was observed in a single CuO nanowire synthesized using a thermal oxidation method. The confocal Raman spectra of a single CuO nanowire permit direct observation of the nature of an individual CuO nanowire. The parameter order obtained from the inverse Raman B g 2 peak linewidth results in the length dependence of the linewidth and a short-circuit diffusion length of 3.3 μm. The observed structural information is also consistent with the energy dispersive x-ray spectroscopic mapping. The results confirm that the growth of CuO nanowires occurs through the short-circuit diffusion mechanism

  3. Short-term outcomes of transcatheter closure of secundum atrial septal defect in children and adolescents: An experience of two centers in Upper Egypt

    Directory of Open Access Journals (Sweden)

    Safaa H. Ali

    2018-01-01

    Conclusions: Transcatheter closure of ASDs in children and adolescents was feasible and safe in the first 4 years experience in our centers, with good short-term outcome. Balloon sizing is not necessary for transcatheter closure of secundum ASD. Multiple defects can be safety closed by a single device.

  4. Type 2 diabetes mellitus induces congenital heart defects in murine embryos by increasing oxidative stress, endoplasmic reticulum stress, and apoptosis.

    Science.gov (United States)

    Wu, Yanqing; Reece, E Albert; Zhong, Jianxiang; Dong, Daoyin; Shen, Wei-Bin; Harman, Christopher R; Yang, Peixin

    2016-09-01

    Maternal type 1 and 2 diabetes mellitus are strongly associated with high rates of severe structural birth defects, including congenital heart defects. Studies in type 1 diabetic embryopathy animal models have demonstrated that cellular stress-induced apoptosis mediates the teratogenicity of maternal diabetes leading to congenital heart defect formation. However, the mechanisms underlying maternal type 2 diabetes mellitus-induced congenital heart defects remain largely unknown. We aim to determine whether oxidative stress, endoplasmic reticulum stress, and excessive apoptosis are the intracellular molecular mechanisms underlying maternal type 2 diabetes mellitus-induced congenital heart defects. A mouse model of maternal type 2 diabetes mellitus was established by feeding female mice a high-fat diet (60% fat). After 15 weeks on the high-fat diet, the mice showed characteristics of maternal type 2 diabetes mellitus. Control dams were either fed a normal diet (10% fat) or the high-fat diet during pregnancy only. Female mice from the high-fat diet group and the 2 control groups were mated with male mice that were fed a normal diet. At E12.5, embryonic hearts were harvested to determine the levels of lipid peroxides and superoxide, endoplasmic reticulum stress markers, cleaved caspase 3 and 8, and apoptosis. E17.5 embryonic hearts were harvested for the detection of congenital heart defect formation using India ink vessel patterning and histological examination. Maternal type 2 diabetes mellitus significantly induced ventricular septal defects and persistent truncus arteriosus in the developing heart, along with increasing oxidative stress markers, including superoxide and lipid peroxidation; endoplasmic reticulum stress markers, including protein levels of phosphorylated-protein kinase RNA-like endoplasmic reticulum kinase, phosphorylated-IRE1α, phosphorylated-eIF2α, C/EBP homologous protein, and binding immunoglobulin protein; endoplasmic reticulum chaperone gene

  5. Hypotrophy of conduit artery walls of the offspring of nitric oxide-defective rats

    Directory of Open Access Journals (Sweden)

    Kristek F.

    2004-01-01

    Full Text Available The objective of the present study was to investigate the structure of the arterial walls of the offspring stemming from nitric oxide (NO-defective hypertensive parents. The parents were treated with N G-nitro-L-arginine methyl ester (40 mg kg-1 day-1 for 5 weeks. Blood pressure was measured noninvasively in six 30-day-old rats and nine age-matched controls. The cardiovascular system was perfused with glutaraldehyde at 120 mmHg. The thoracic aorta and carotid artery were processed for electron microscopy, and geometry was determined by light microscopy. Endothelial cells, smooth muscle cells (SMC and extracellular matrix (ECM were determined by the point counting method in electron micrographs of the carotid artery. The blood pressure of experimental offspring was 150.0 ± 2.3 vs 104.6 ± 2.1 mmHg (P < 0.01 for the controls and their heart/body weight ratio of 3.9 ± 0.1 vs 4.4 ± 0.2 (P < 0.05 for the controls indicated cardiac hypotrophy. The wall thickness (tunica intima and media of the thoracic aorta and carotid artery of experimental offspring was decreased to 78.9% (P < 0.01 and 83.8% (P < 0.01, respectively, compared to controls, as confirmed by a respective cross-sectional area of 85.3% (P < 0.01 and 84.1% (P < 0.01. The wall thickness/inner diameter ratio was reduced to 75% (P < 0.01 in the thoracic artery and to 81.5% (P < 0.01 in the carotid artery. No change in endothelial cell volume density or ECM was observed in the tunica intima of the carotid artery, and SMC volume density was lower in the tunica media (37.6 ± 0.9 vs 44.7 ± 1.1% for controls, P < 0.01, indicating compromised SMC development. Interference with arginine metabolism, a decrease in NO, and other factors are possible mechanisms underlying the structural alterations of the cardiovascular system of offspring from NO-defective hypertensive rats.

  6. The effect of sepsis and short-term exposure to nitrous oxide on the ...

    African Journals Online (AJOL)

    It is recognised that prolonged anaesthesia with nitrous oxide (N20) induces megaloblastic anaemia by oxidising vitamin B12 To determine whether sepsis aggravates the effect of H20 on haemopoiesis 5 patients with severe sepsis, who required surgery and were exposed to short-term (45 - 105 minutes) N20 anaesthesia, ...

  7. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Directory of Open Access Journals (Sweden)

    Hatim Alnoor

    2015-08-01

    Full Text Available Hexagonal c-axis oriented zinc oxide (ZnO nanorods (NRs with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL spectra were collected for all samples. Cathodoluminescence (CL spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE to the deep-level emission (DLE peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h, which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  8. Thermogravimetric analysis and TEM characterization of the oxidation and defect sites of carbon nanotubes synthesized by CVD of methane

    International Nuclear Information System (INIS)

    Li Haipeng; Zhao Naiqin; He Chunnian; Shi Chunsheng; Du Xiwen; Li Jiajun

    2008-01-01

    Changes in the thermogravimetrically determined oxidation behaviors of CVD-grown multi-walled carbon nanotubes (MWNTs) over Ni/Al catalyst with different Ni content were examined. Catalyst type was found to have a measurable impact upon nanotube stability, suggesting differing levels of crystalline perfection in the resulting nanotubes. With increasing the Ni content in the Ni/Al catalyst, the CNTs obtained became less stable during heat treatment in air. Furthermore, high-resolution transmission electron microscopy was employed to investigate the defect sites of as-grown MWNTs. The results provide evidence showing that defect sites along the walls and at the ends of the raw MWNTs facilitate the thermal oxidative destruction of the nanotubes

  9. Issues in first-principles calculations for defects in semiconductors and oxides

    International Nuclear Information System (INIS)

    Nieminen, Risto M

    2009-01-01

    Recent advances in density-functional theory (DFT) calculations of defect electronic properties in semiconductors and insulators are discussed. In particular, two issues are addressed: the band-gap underestimation of standard density-functional methods with its harmful consequences for the positioning of defect-related levels in the band-gap region, and the slow convergence of calculated defect properties when the periodic supercell approach is used. Systematic remedies for both of these deficiencies are now available, and are being implemented in the context of popular DFT codes. This should help in improving the parameter-free accuracy and thus the predictive power of the methods to enable unambiguous explanation of defect-related experimental observations. These include not only the various fingerprint spectroscopies for defects but also their thermochemistry and dynamics, i.e. the temperature-dependent concentration and diffusivities of defects under various doping conditions and in different stoichiometries

  10. Abnormal photothermal effect of laser radiation on highly defect oxide bronze nanoparticles under the sub-threshold excitation of absorption

    Science.gov (United States)

    Gulyaev, P.; Kotvanova, M.; Omelchenko, A.

    2017-05-01

    The mechanism of abnormal photo-thermal effect of laser radiation on nanoparticles of oxide bronzes has been proposed in this paper. The basic features of the observed effect are: a) sub-threshold absorption of laser radiation by the excitation of donor-like levels formed in the energy gap due to superficial defects of the oxide bronze nano-crystals; b) an interband radiationless transition of energy of excitation on deep triplet levels and c) consequent recombination occurring at the plasmon absorption. K or Na atoms thermally intercalated to the octahedral crystal structure of TiO2 in the wave SHS combustion generate acceptor levels in the gap. The prepared oxide bronzes of the non-stoichiometric composition NaxTiO2 and KxTiO2 were examined by high resolution TEM, and then grinded in a planetary mill with powerful dispersion energy density up to 4000 J/g. This made it possible to obtain nanoparticles about 50 nm with high surface defect density (1017-1019 cm-2 at a depth of 10 nm). High photo-thermal effect of laser radiation on the defect nanocrystals observed after its impregnation into cartilaginous tissue exceeds 7 times in comparison with the intact ones.

  11. Strain and Defect Engineering for Tailored Electrical Properties in Perovskite Oxide Thin Films and Superlattices

    Science.gov (United States)

    Hsing, Greg Hsiang-Chun

    Functional complex-oxides display a wide spectrum of physical properties, including ferromagnetism, piezoelectricity, ferroelectricity, photocatalytic and metal-insulating transition (MIT) behavior. Within this family, oxides with a perovskite structure have been widely studied, especially in the form of thin films and superlattices (heterostructures), which are strategically and industrially important because they offer a wide range of opportunities for electronic, piezoelectric and sensor applications. The first part of my thesis focuses on understanding and tuning of the built-in electric field found in PbTiO3/SrTiO3 (PTO/STO) ferroelectric superlattices and other ferroelectric films. The artificial layering in ferroelectric superlattices is a potential source of polarization asymmetry, where one polarization state is preferred over another. One manifestation of this asymmetry is a built-in electric field associated with shifted polarization hysteresis. Using off-axis RF-magnetron sputtering, we prepared several compositions of PTO/STO superlattice thin films; and for comparison PbTiO3/SrRuO 3 (PTO/SRO) superlattices, which have an additional intrinsic compositional asymmetry at the interface. Both theoretical modeling and experiments indicate that the layer-by-layer superlattice structure aligns the Pb-O vacancy defect dipoles in the c direction which contributes significantly to the built-in electric field; however the preferred polarization direction is different between the PTO/STO and PTO/SRO interface. By designing a hybrid superlattice that combines PTO/STO and PTO/SRO superlattices, we show the built-in electric field can be tuned to zero by changing the composition of the combo-superlattice. The second part of my thesis focuses on the epitaxial growth of SrCrO 3 (SCO) films. The inconsistent reports regarding its electrical and magnetic properties through the years stem from the compositionally and structurally ill-defined polycrystalline samples, but

  12. Magnetic electrospun short nanofibers wrapped graphene oxide as a promising biomaterials for guiding cellular behavior.

    Science.gov (United States)

    Feng, Zhang-Qi; Shi, Chuanmei; Zhao, Bin; Wang, Ting

    2017-12-01

    Magnetic particles show extremely wide application prospects in the biomedical field, particularly in the success of cellular manipulation, drug delivery systems, magnetic hyperthermia and NRI contrast enhancement. Graphene oxide with functional groups has a promising biological effect. In this work, we develop magnetic short-fibers wrapped graphene oxide for guiding cellular behavior with the aid of high-speed shear of nanofibers fabricated through electrospinning technique. The diameter and the length of short-fibers are about 300nm and 80μm, respectively. The short-fibers exhibit superior magnetic properties (saturation magnetization value: 50.33emu/g), which has a strong response appearance to the NdFeB magnet. SEM images and laser confocal images display that there has an extremely tight adhesion between the short-fibers wrapped graphene oxide and cells. The control of cell-fibers structure behavior can be realized by applying external magnet. The results may provide an attractive perspective on the treatment of disease with magnetic field. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Influence of Short-time Oxidation on Corrosion Properties of Directionally Solidified Superalloys with Different Orientations

    Directory of Open Access Journals (Sweden)

    MA Luo-ning

    2016-07-01

    Full Text Available In order to investigate the corrosion performance on intersecting and longitudinal surfaces of unoxidized and oxidized directionally solidified superalloys, Ni-base directionally solidified superalloy DZ125 and Co-base directionally solidified superalloy DZ40M were selected. Oxidation behavior on both alloys with different orientations was investigated at 1050℃ at different times, simulating the oxidation process of vanes or blades in service; subsequent electrochemical performance in 3.5%NaCl aqueous solution was studied on two orientations of unoxidized and oxidized alloys, simulating the corrosion process of superalloy during downtime. The results show that grain boundaries and sub-boundaries of directionally solidified superalloys are susceptible to corrosion and thus longitudinal surface with lower area fraction of grain boundaries has higher corrosion resistance. Compared to intersecting surface of alloys, the structure of grain boundaries of longitudinal surface is less conducive to diffusion and thus the oxidation rate on longitudinal surface is lower. Formation of oxide layers on alloys after short-time oxidation provides protective effect and enhances the corrosion resistance.

  14. A point defect model for the general and pitting corrosion on iron-oxide-electrolyte interface deduced from current oscillations

    CERN Document Server

    Pagitsas, M; Sazou, D

    2003-01-01

    Analysis of the passive-active oscillatory region of the Fe-0.75 M H sub 2 SO sub 4 system, perturbed by adding small amounts of halide species, allow the distinction between pitting and general corrosion. Complex periodic and aperiodic current oscillations characterize pitting corrosion whereas monoperiodic oscillations of a relaxation type indicate general corrosion. A point defect model (PDM) is considered for the microscopic description of the growth and breakdown of the iron oxide film. The physicochemical processes leading to different types of corrosion can be clarified in terms of the PDM. Occupation of an anion vacancy by a halide ion results in the localized attack of the passive oxide and pitting corrosion. On the other hand, the formation of surface soluble iron complexes is related to the uniform dissolution of the passive oxide and general corrosion.

  15. Short (

    NARCIS (Netherlands)

    Telleman, Gerdien; den Hartog, Laurens

    2013-01-01

    Aim: This systematic review assessed the implant survival rate of short (<10 mm) dental implants installed in partially edentulous patients. A case report of a short implant in the posterior region have been added. Materials and methods: A search was conducted in the electronic databases of MEDLINE

  16. 3D imaging of intrinsic crystalline defects in zinc oxide by spectrally resolved two-photon fluorescence microscopy

    Science.gov (United States)

    Al-Tabich, A.; Inami, W.; Kawata, Y.; Jablonski, R.; Worasawat, S.; Mimura, H.

    2017-05-01

    We present a method for three-dimensional intrinsic defect imaging in zinc oxide (ZnO) by spectrally resolved two-photon fluorescence microscopy, based on the previously presented method of observing a photoluminescence distribution in wide-gap semiconductor crystals [Noor et al., Appl. Phys. Lett. 92(16), 161106 (2008)]. A tightly focused light beam radiated by a titanium-sapphire laser is used to obtain a two-photon excitation of selected area of the ZnO sample. Photoluminescence intensity of a specific spectral range is then selected by optical band pass filters and measured by a photomultiplier tube. Reconstruction of the specimen image is done by scanning the volume of interest by a piezoelectric positioning stage and measuring the spectrally resolved photoluminescence intensity at each point. The method has been proved to be effective at locating intrinsic defects of the ZnO crystalline structure in the volume of the crystal. The method was compared with other defect imaging and 3D imaging techniques like scanning tunneling microscopy and confocal microscopy. In both cases, our method shows superior penetration abilities and, as the only method, allows location of the defects of the chosen type in 3D. In this paper, we present the results of oxygen vacancies and zinc antisites imaging in ZnO nanorods.

  17. Chitosan-Graphene Oxide 3D scaffolds as Promising Tools for Bone Regeneration in Critical-Size Mouse Calvarial Defects.

    Science.gov (United States)

    Hermenean, Anca; Codreanu, Ada; Herman, Hildegard; Balta, Cornel; Rosu, Marcel; Mihali, Ciprian Valentin; Ivan, Alexandra; Dinescu, Sorina; Ionita, Mariana; Costache, Marieta

    2017-11-30

    Limited self-regenerating capacity of human skeleton makes the reconstruction of critical size bone defect a significant challenge for clinical practice. Aimed for regenerating bone tissues, this study was designed to investigate osteogenic differentiation, along with bone repair capacity of 3D chitosan (CHT) scaffolds enriched with graphene oxide (GO) in critical-sized mouse calvarial defect. Histopathological/histomorphometry and scanning electron microscopy(SEM) analysis of the implants revealed larger amount of new bone in the CHT/GO-filled defects compared with CHT alone (p < 0.001). When combined with GO, CHT scaffolds synergistically promoted the increase of alkaline phosphatase activity both in vitro and in vivo experiments. This enhanced osteogenesis was corroborated with increased expression of bone morphogenetic protein (BMP) and Runx-2 up to week 4 post-implantation, which showed that GO facilitates the differentiation of osteoprogenitor cells. Meanwhile, osteogenesis was promoted by GO at the late stage as well, as indicated by the up-regulation of osteopontin and osteocalcin at week 8 and overexpressed at week 18, for both markers. Our data suggest that CHT/GO biomaterial could represent a promising tool for the reconstruction of large bone defects, without using exogenous living cells or growth factors.

  18. A retrotransposon insertion in the 5' regulatory domain of Ptf1a results in ectopic gene expression and multiple congenital defects in Danforth's short tail mouse.

    Directory of Open Access Journals (Sweden)

    Francesca Lugani

    Full Text Available Danforth's short tail mutant (Sd mouse, first described in 1930, is a classic spontaneous mutant exhibiting defects of the axial skeleton, hindgut, and urogenital system. We used meiotic mapping in 1,497 segregants to localize the mutation to a 42.8-kb intergenic segment on chromosome 2. Resequencing of this region identified an 8.5-kb early retrotransposon (ETn insertion within the highly conserved regulatory sequences upstream of Pancreas Specific Transcription Factor, 1a (Ptf1a. This mutation resulted in up to tenfold increased expression of Ptf1a as compared to wild-type embryos at E9.5 but no detectable changes in the expression levels of other neighboring genes. At E9.5, Sd mutants exhibit ectopic Ptf1a expression in embryonic progenitors of every organ that will manifest a developmental defect: the notochord, the hindgut, and the mesonephric ducts. Moreover, at E 8.5, Sd mutant mice exhibit ectopic Ptf1a expression in the lateral plate mesoderm, tail bud mesenchyme, and in the notochord, preceding the onset of visible defects such as notochord degeneration. The Sd heterozygote phenotype was not ameliorated by Ptf1a haploinsufficiency, further suggesting that the developmental defects result from ectopic expression of Ptf1a. These data identify disruption of the spatio-temporal pattern of Ptf1a expression as the unifying mechanism underlying the multiple congenital defects in Danforth's short tail mouse. This striking example of an enhancer mutation resulting in profound developmental defects suggests that disruption of conserved regulatory elements may also contribute to human malformation syndromes.

  19. Layered sphere-shaped TiO₂ capped with gold nanoparticles on structural defects and their catalysis of formaldehyde oxidation.

    Science.gov (United States)

    Ma, Chunyan; Pang, Guanglong; He, Guangzhi; Li, Yang; He, Chi; Hao, Zhengping

    2016-01-01

    We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials, which were formed by layered deposition of multiple anatase TiO2 nanosheets. The Au nanoparticles were stabilized by structural defects in each TiO2 nanosheet, including crystal steps and edges, thereby fixing the Au-TiO2 perimeter interface. Reactant transfer occurred along the gaps between these TiO2 nanosheet layers and in contact with catalytically active sites at the Au-TiO2 interface. The doped Au induced the formation of oxygen vacancies in the Au-TiO2 interface. Such vacancies are essential for generating active oxygen species (*O(-)) on the TiO2 surface and Ti(3+) ions in bulk TiO2. These ions can then form Ti(3+)-O(-)-Ti(4+) species, which are known to enhance the catalytic activity of formaldehyde (HCHO) oxidation. These studies on structural and oxygen vacancy defects in Au/TiO2 samples provide a theoretical foundation for the catalytic mechanism of HCHO oxidation on oxide-supported Au materials. Copyright © 2015. Published by Elsevier B.V.

  20. Electronic Structure of the Perylene / Zinc Oxide Interface: A Computational Study of Photoinduced Electron Transfer and Impact of Surface Defects

    KAUST Repository

    Li, Jingrui

    2015-07-29

    The electronic properties of dye-sensitized semiconductor surfaces consisting of pery- lene chromophores chemisorbed on zinc oxide via different spacer-anchor groups, have been studied at the density-functional-theory level. The energy distributions of the donor states and the rates of photoinduced electron transfer from dye to surface are predicted. We evaluate in particular the impact of saturated versus unsaturated aliphatic spacer groups inserted between the perylene chromophore and the semiconductor as well as the influence of surface defects on the electron-injection rates.

  1. Defect-induced magnetism in undoped and Mn-doped wide band gapzinc oxide grown by aerosol spray pyrolysis

    CSIR Research Space (South Africa)

    Motaung, DE

    2014-08-01

    Full Text Available Surface Science Vol. 311, pp 14-26 Defect-induced magnetism in undoped and Mn-doped wide band gapzinc oxide grown by aerosol spray pyrolysis D.E. Motaunga,∗, I. Kortidise, D. Papadakie, S.S. Nkosib,∗∗, G.H. Mhlongoa,J. Wesley-Smitha, G.F. Malgasc, B....W. Mwakikungaa, E. Coetseed, H.C. Swartd,G. Kiriakidise,f, S.S. Raya aDST/CSIR Nanotechnology Innovation Centre, National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, P.O. Box 395,Pretoria 0001, South Africa b...

  2. Electronic Structure of the Perylene / Zinc Oxide Interface: A Computational Study of Photoinduced Electron Transfer and Impact of Surface Defects

    KAUST Repository

    Li, Jingrui; Li, Hong; Winget, Paul; Bredas, Jean-Luc

    2015-01-01

    The electronic properties of dye-sensitized semiconductor surfaces consisting of pery- lene chromophores chemisorbed on zinc oxide via different spacer-anchor groups, have been studied at the density-functional-theory level. The energy distributions of the donor states and the rates of photoinduced electron transfer from dye to surface are predicted. We evaluate in particular the impact of saturated versus unsaturated aliphatic spacer groups inserted between the perylene chromophore and the semiconductor as well as the influence of surface defects on the electron-injection rates.

  3. 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

  4. Electronic properties of hafnium oxide: A contribution from defects and traps

    Energy Technology Data Exchange (ETDEWEB)

    Gritsenko, Vladimir A., E-mail: grits@isp.nsc.ru; Perevalov, Timofey V.; Islamov, Damir R., E-mail: damir@isp.nsc.ru

    2016-02-15

    In the present article, we give a review of modern data and latest achievements pertaining to the study of electronic properties of oxygen vacancies in hafnium oxide. Hafnium oxide is a key dielectric for use in many advanced silicon devices. Oxygen vacancies in hafnium oxide largely determine the electronic properties of the material. We show that the electronic transitions between the states due to oxygen vacancies largely determine the optical absorption and luminescent properties of hafnium oxide. We discuss the role of oxygen vacancies as traps that facilitate charge transport in hafnium oxide films. Also, we demonstrate the fact that the electrical conductivity in hafnium oxide is controlled by the phonon-assisted tunnelling of charge carriers between traps that were identified as oxygen vacancies.

  5. Coffee-Ring Defined Short Channels for Inkjet-Printed Metal Oxide Thin-Film Transistors.

    Science.gov (United States)

    Li, Yuzhi; Lan, Linfeng; Xiao, Peng; Sun, Sheng; Lin, Zhenguo; Song, Wei; Song, Erlong; Gao, Peixiong; Wu, Weijing; Peng, Junbiao

    2016-08-03

    Short-channel electronic devices several micrometers in length are difficult to implement by direct inkjet printing due to the limitation of position accuracy of the common inkjet printer system and the spread of functional ink on substrates. In this report, metal oxide thin-film transistors (TFTs) with channel lengths of 3.5 ± 0.7 μm were successfully fabricated with a common inkjet printer without any photolithography steps. Hydrophobic CYTOP coffee stripes, made by inkjet-printing and plasma-treating processes, were utilized to define the channel area of TFTs with channel lengths as short as ∼3.5 μm by dewetting the inks of the source/drain (S/D) precursors. Furthermore, by introduction of an ultrathin layer of PVA to modify the S/D surfaces, the spreading of precursor ink of the InOx semiconductor layer was well-controlled. The inkjet-printed short-channel TFTs exhibited a maximum mobility of 4.9 cm(2) V(-1) s(-1) and an on/off ratio of larger than 10(9). This approach of fabricating short-channel TFTs by inkjet printing will promote the large-area fabrication of short-channel TFTs in a cost-effective manner.

  6. Defect states and room temperature ferromagnetism in cerium oxide nanopowders prepared by decomposition of Ce-propionate

    DEFF Research Database (Denmark)

    Mihalache, V.; Grivel, J. C.; Secu, M.

    2018-01-01

    . An improvement of ferromagnetism and intensity of defect-related PL emission was observed when annealing the products in which nanocrystalline cerium oxide coexists with Ce - oxicarbonate traces, Ce2O2CO3. The experimental results were explained based on the following considerations: room temperature......Four batches of cerium oxide powders (with nanocrystallite size of 6.9 nm–572 nm) were prepared from four precursor nanopowders by thermal decomposition of Ce-propionate and annealing in air between 250 °C–1200 °C for 10 min–240 min. Ceria formation reactions, structure, vibrational, luminescence...... and magnetic properties were investigated by differential scanning calorimetry, x-ray diffraction, electron microscopy, infrared spectroscopy, photoluminescence and SQUID. All the samples exhibit room temperature ferromagnetism, RTFM, (with coercivity, Hc, of 8 Oe - 121 Oe and saturation magnetization, Ms...

  7. Visualizing chemical states and defects induced magnetism of graphene oxide by spatially-resolved-X-ray microscopy and spectroscopy.

    Science.gov (United States)

    Wang, Y F; Singh, Shashi B; Limaye, Mukta V; Shao, Y C; Hsieh, S H; Chen, L Y; Hsueh, H C; Wang, H T; Chiou, J W; Yeh, Y C; Chen, C W; Chen, C H; Ray, Sekhar C; Wang, J; Pong, W F; Takagi, Y; Ohigashi, T; Yokoyama, T; Kosugi, N

    2015-10-20

    This investigation studies the various magnetic behaviors of graphene oxide (GO) and reduced graphene oxides (rGOs) and elucidates the relationship between the chemical states that involve defects therein and their magnetic behaviors in GO sheets. Magnetic hysteresis loop reveals that the GO is ferromagnetic whereas photo-thermal moderately reduced graphene oxide (M-rGO) and heavily reduced graphene oxide (H-rGO) gradually become paramagnetic behavior at room temperature. Scanning transmission X-ray microscopy and corresponding X-ray absorption near-edge structure spectroscopy were utilized to investigate thoroughly the variation of the C 2p(π*) states that are bound with oxygen-containing and hydroxyl groups, as well as the C 2p(σ*)-derived states in flat and wrinkle regions to clarify the relationship between the spatially-resolved chemical states and the magnetism of GO, M-rGO and H-rGO. The results of X-ray magnetic circular dichroism further support the finding that C 2p(σ*)-derived states are the main origin of the magnetism of GO. Based on experimental results and first-principles calculations, the variation in magnetic behavior from GO to M-rGO and to H-rGO is interpreted, and the origin of ferromagnetism is identified as the C 2p(σ*)-derived states that involve defects/vacancies rather than the C 2p(π*) states that are bound with oxygen-containing and hydroxyl groups on GO sheets.

  8. Structure, Raman spectra and defect chemistry modelling of conductive pyrochlore oxides

    DEFF Research Database (Denmark)

    Poulsen, F.W.; Glerup, M.; Holtappels, P.

    2000-01-01

    -O(x) and V-O on the O site, interstitial oxygens O-i", and delocalised electrons and electron holes. Four mass action law expressions govern such a model. The defect model can rationalise why home-valent doping, i.e. substitution of Zr(4+) by Ce(4+), can lead to an increase in ionic conductivity...

  9. Defect engineering of mesoporous nickel ferrite and its application for highly enhanced water oxidation catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Yue, Qiudi; Liu, Cunming; Wan, Yangyang; Wu, Xiaojun; Zhang, Xiaoyi; Du, Pingwu

    2018-02-01

    Spinel nickel ferrite (NiFe2O4) emerges as a promising low-cost catalyst for water splitting but it usually shows low catalytic activity because of its limited number of active sites and poor conductivity. For the first time, herein we have successfully overcome its weaknesses using defect engineering approach by creating oxygen vacancies in NiFe2O4. The existence of oxygen vacancy not only shifts up the d-band center, strengthens the adsorption of H2O, and thus provides more active catalytic sites, but also tunes the electron configuration and creates massive number of defective donor states in the band gap to facilitate charge transfer processes. The optimal defective catalyst showed significantly enhanced catalytic OER performance with an OER overpotential as low as 0.35 V at 10 mA cm-2 and a Tafel slope of only ~40 mV dec-1. Moreover, the impressive specific mass and area current density of 17.5 A g-1 and 0.106 A m-2 at 1.58 V vs. RHE have been achieved, which are ~23 and ~36 times higher than that of defect-free counterpart, respectively.

  10. Thermal evolution of defects in undoped zinc oxide grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zilan; Su, Shichen; Ling, Francis Chi-Chung, E-mail: ccling@hku.hk [Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Anwand, W.; Wagner, A. [Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany)

    2014-07-21

    Undoped ZnO films are grown by pulsed laser deposition on c-plane sapphire with different oxygen pressures. Thermal evolutions of defects in the ZnO films are studied by secondary ion mass spectroscopy (SIMS), Raman spectroscopy, and positron annihilation spectroscopy (PAS), and with the electrical properties characterized by the room temperature Hall measurement. Oxygen deficient defect related Raman lines 560 cm{sup −1} and 584 cm{sup −1} are identified and their origins are discussed. Thermal annealing induces extensive Zn out-diffusion at the ZnO/sapphire interface and leaves out Zn-vacancy in the ZnO film. Two types of Zn-vacancy related defects with different microstructures are identified in the films. One of them dominates in the samples grown without oxygen. Annealing the sample grown without oxygen or growing the samples in oxygen would favor the Zn-vacancy with another microstructure, and this Zn-vacancy defect persists after 1100 °C annealing.

  11. Thermal evolution of defects in undoped zinc oxide grown by pulsed laser deposition

    Science.gov (United States)

    Wang, Zilan; Su, Shichen; Ling, Francis Chi-Chung; Anwand, W.; Wagner, A.

    2014-07-01

    Undoped ZnO films are grown by pulsed laser deposition on c-plane sapphire with different oxygen pressures. Thermal evolutions of defects in the ZnO films are studied by secondary ion mass spectroscopy (SIMS), Raman spectroscopy, and positron annihilation spectroscopy (PAS), and with the electrical properties characterized by the room temperature Hall measurement. Oxygen deficient defect related Raman lines 560 cm-1 and 584 cm-1 are identified and their origins are discussed. Thermal annealing induces extensive Zn out-diffusion at the ZnO/sapphire interface and leaves out Zn-vacancy in the ZnO film. Two types of Zn-vacancy related defects with different microstructures are identified in the films. One of them dominates in the samples grown without oxygen. Annealing the sample grown without oxygen or growing the samples in oxygen would favor the Zn-vacancy with another microstructure, and this Zn-vacancy defect persists after 1100 °C annealing.

  12. Thermal evolution of defects in undoped zinc oxide grown by pulsed laser deposition

    International Nuclear Information System (INIS)

    Wang, Zilan; Su, Shichen; Ling, Francis Chi-Chung; Anwand, W.; Wagner, A.

    2014-01-01

    Undoped ZnO films are grown by pulsed laser deposition on c-plane sapphire with different oxygen pressures. Thermal evolutions of defects in the ZnO films are studied by secondary ion mass spectroscopy (SIMS), Raman spectroscopy, and positron annihilation spectroscopy (PAS), and with the electrical properties characterized by the room temperature Hall measurement. Oxygen deficient defect related Raman lines 560 cm −1 and 584 cm −1 are identified and their origins are discussed. Thermal annealing induces extensive Zn out-diffusion at the ZnO/sapphire interface and leaves out Zn-vacancy in the ZnO film. Two types of Zn-vacancy related defects with different microstructures are identified in the films. One of them dominates in the samples grown without oxygen. Annealing the sample grown without oxygen or growing the samples in oxygen would favor the Zn-vacancy with another microstructure, and this Zn-vacancy defect persists after 1100 °C annealing.

  13. Characterization and evaluation of graphene oxide scaffold for periodontal wound healing of class II furcation defects in dog.

    Science.gov (United States)

    Kawamoto, Kohei; Miyaji, Hirofumi; Nishida, Erika; Miyata, Saori; Kato, Akihito; Tateyama, Akito; Furihata, Tomokazu; Shitomi, Kanako; Iwanaga, Toshihiko; Sugaya, Tsutomu

    2018-01-01

    The 3-dimensional scaffold plays a key role in volume and quality of repair tissue in periodontal tissue engineering therapy. We fabricated a novel 3D collagen scaffold containing carbon-based 2-dimensional layered material, named graphene oxide (GO). The aim of this study was to characterize and assess GO scaffold for periodontal tissue healing of class II furcation defects in dog. GO scaffolds were prepared by coating the surface of a 3D collagen sponge scaffold with GO dispersion. Scaffolds were characterized using cytotoxicity and tissue reactivity tests. In addition, GO scaffold was implanted into dog class II furcation defects and periodontal healing was investigated at 4 weeks postsurgery. GO scaffold exhibited low cytotoxicity and enhanced cellular ingrowth behavior and rat bone forming ability. In addition, GO scaffold stimulated healing of dog class II furcation defects. Periodontal attachment formation, including alveolar bone, periodontal ligament-like tissue, and cementum-like tissue, was significantly increased by GO scaffold implantation, compared with untreated scaffold. The results suggest that GO scaffold is biocompatible and possesses excellent bone and periodontal tissue formation ability. Therefore, GO scaffold would be beneficial for periodontal tissue engineering therapy.

  14. Short-Term Caloric Restriction Suppresses Cardiac Oxidative Stress and Hypertrophy Caused by Chronic Pressure Overload.

    Science.gov (United States)

    Kobara, Miyuki; Furumori-Yukiya, Akiko; Kitamura, Miho; Matsumura, Mihoko; Ohigashi, Makoto; Toba, Hiroe; Nakata, Tetsuo

    2015-08-01

    Caloric restriction (CR) prevents senescent changes, in which reactive oxygen species (ROS) have a critical role. Left ventricular (LV) hypertrophy is a risk factor for cardiovascular diseases. We examined whether CR alters cardiac redox state and hypertrophy from chronic pressure overload. Male c57BL6 mice were subjected to ascending aortic constriction (AAC) with ad libitum caloric intake (AL + AAC group) or 40% restricted caloric intake (CR + AAC group). CR was initiated 2 weeks before AAC and was continued for 4 weeks. Two weeks after constriction, AAC increased LV wall thickness, impaired transmitral flow velocity, and augmented myocyte hypertrophy and fibrosis, in association with enhancement of BNP and collagen III expressions in the AL + AAC group. In the AL + AAC group, oxidative stress in cardiac tissue and mitochondria were enhanced, and NADPH oxidase activity and mitochondrial ROS production were elevated. These changes were significantly attenuated in the CR + AAC group. Additionally, in antioxidant systems, myocardial glutathione peroxidase and superoxide dismutase activities were enhanced in the CR + AAC group. Chronic pressure overload increased cardiac oxidative damage, in association with cardiac hypertrophy and fibrosis. Short-term CR suppressed oxidative stress and improved cardiac function, suggesting that short-term CR could be a useful strategy to prevent pressure overload-induced cardiac injury. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Synthesis and characterization of magnesium oxide nanocrystallites and probing the vacancy-type defects through positron annihilation studies

    Science.gov (United States)

    Das, Anjan; Mandal, Atis Chandra; Roy, Soma; Prashanth, Pendem; Ahamed, Sk Izaz; Kar, Subhrasmita; Prasad, Mithun S.; Nambissan, P. M. G.

    2016-09-01

    Magnesium oxide nanocrystallites exhibit certain abnormal characteristics when compared to those of other wide band gap oxide semiconductors in the sense they are most prone to water absorption and formation of a hydroxide layer on the surface. The problem can be rectified by heating and pure nanocrystallites can be synthesized with controllable sizes. Inevitably the defect properties are distinctly divided between two stages, the one with the hydroxide layer (region I) and the other after the removal of the layer by annealing (region II). The lattice parameters, the optical band gap and even the positron annihilation characteristics are conspicuous by their distinct behavior in the two stages of the surface configurations of nanoparticles. While region I was specific with the formation of positronium-hydrogen complexes that drastically altered the defect-specific positron lifetimes, pick-off annihilation of orthopositronium atoms marked region II. The vacancy clusters within the nanocrystallites also trapped positrons. They agglomerated due to the effect of the higher temperatures and resulted in the growth of the nanocrystallites. The coincidence Doppler broadening spectroscopic measurements supported these findings and all the more indicated the trapping of positrons additionally into the neutral divacancies and negatively charged trivacancies. This is apart from the Mg2+ monovacancies which acted as the dominant trapping centers for positrons.

  16. The Effects of Oxidation Layer, Temperature, and Stress on Tin Whisker Growth: A Short Review

    Science.gov (United States)

    Mahim, Z.; Salleh, M. A. A.; Khor, C. Y.

    2018-03-01

    In order to reduce the Tin (Sn) whisker growth phenomenon in solder alloys, the researcher all the world has studied the factor of this behaviour. However, this phenomenon still hunted the electronic devices and industries. The whiskers growth were able to cause the electrical short, which would lead to the catastrophic such as plane crush, the failure of heart pacemaker, and the lost satellite connection. This article focuses on the three factors that influence the whiskers growth in solder alloys which is stress, oxidation layer and temperature. This findings were allowed the researchers to develop various method on how to reduce the growth of the Sn whiskers.

  17. Defects in quasi-one dimensional oxide conductors: K0.3MoO3

    International Nuclear Information System (INIS)

    Smith, K.E.; Breuer, K.; Goldberg, D.; Greenblatt, M.; McCarroll, W.; Hulbert, S.L.

    1995-01-01

    The electronic structure of the prototypical quasi-one dimensional (ID) conductor K 0.3 MoO 3 has been studied using high resolution photoemission spectroscopy. In particular, the electronic structure of defects was investigated in order to understand the mechanism for charge density wave pinning and destruction of the Peierls transition. Defects were found to radically alter the electronic structure close to the Fermi level (E F ), thus strongly modifying the structure of the Fermi surface. While a low emission intensity at E F has been interpreted as evidence for a Luttinger liquid ground state in a 1D metal, the authors show that non-stoichiometric surfaces lead to similar effects. The nature of the ground state is discussed in the context of these results

  18. Anomalous high photoconductivity in short channel indium-zinc-oxide photo-transistors

    International Nuclear Information System (INIS)

    Choi, Hyun-Sik; Jeon, Sanghun

    2015-01-01

    Upon light exposure, an indium-zinc-oxide (IZO) thin-film transistor (TFT) presents higher photoconductivity by several orders of magnitude at the negative gate bias region. Among various device geometrical factors, scaling down the channel length of the photo-transistor results in an anomalous increase in photoconductivity. To probe the origin of this high photoconductivity in short-channel device, we measured transient current, current–voltage, and capacitance–voltage characteristics of IZO–TFTs with various channel lengths and widths before and after illumination. Under the illumination, the equilibrium potential region which lies far from front interface exists only in short-channel devices, forming the un-depleted conducting back channel. This region plays an important role in carrier transport under the illumination, leading to high photoconductivity in short-channel devices. Photon exposure coupled with gate-modulated band bending for short-channel devices leads to the accumulation of V o ++ at the front channel and screening negative gate bias, thereby generating high current flow in the un-depleted back-channel region

  19. Defect mediated reversible ferromagnetism in Co and Mn doped zinc oxide epitaxial films

    Energy Technology Data Exchange (ETDEWEB)

    Mal, Siddhartha; Nori, Sudhakar; Narayan, J. [Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Mula, Suhrit [Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela 769008 (India); Prater, J. T. [Materials Science Division, Army Research Office, Research Triangle Park, North Carolina 27709 (United States)

    2012-12-01

    We have introduced defects in ZnO (undoped and doped with Co and Mn) epitaxial thin films using laser irradiation from nanosecond laser pulses and thermal annealing in oxygen ambient. In contrast to the as grown samples, the laser irradiated films show a significant increase in conductivity, enhancement in UV emission, while maintaining the same wurtzite crystal structure. Room-temperature ferromagnetism (RTFM) is observed in laser-irradiated samples, which increased with the number of laser pulses up to a certain value where magnetic moment saturates. The induced ferromagnetism as well as the enhanced electrical conductivity can be reversed with thermal annealing in oxygen ambient. The magnetization in Co and Mn doped films was found to be strong function of growth conditions and defect concentration. X-ray diffraction and optical absorption experiments suggested a 2+ valance state and tetrahedral coordination for both Co and Mn ions. There is a simultaneous increase in n-type electrical conductivity with the number of laser pulses and continue to exhibit semiconducting behavior in both undoped and doped films. The saturation magnetization was found to be 0.08 {mu}{sub B}/Co and 0.05 {mu}{sub B}/Mn, much lower than 3.0 {mu}{sub B}/Co and 5.0 {mu}{sub B}/Mn, indicating the prominent role of intrinsic defects in RTFM with some contribution from Co{sup 2+}-oxygen vacancy complexes. We propose a unified mechanism based upon introduction of intrinsic defects to explain RTFM and n-type conductivity enhancements during pulsed laser and thermal annealing.

  20. Electron spin resonance of paramagnetic defects and related charge carrier traps in complex oxide scintillators

    Czech Academy of Sciences Publication Activity Database

    Laguta, Valentyn; Nikl, Martin

    2013-01-01

    Roč. 250, č. 2 (2013), s. 254-260 ISSN 0370-1972 R&D Projects: GA MŠk(CZ) LM2011029; GA ČR GAP204/12/0805; GA AV ČR IAA100100810 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : scintillators * point defects * electron spin resonance * polarons Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.605, year: 2013

  1. Short Contribution: Severe Enamel Defects and Malformations of Canines in Pre-Historic and Historic Domestic Pigs from Bohemia

    Czech Academy of Sciences Publication Activity Database

    Teegen, W.-R.; Kyselý, René

    2014-01-01

    Roč. 5, č. 2 (2014), s. 139-146 ISSN 1804-848X Institutional support: RVO:67985912 Keywords : domestic pig (Sus scrofa f. domestica) * enamel defect * enamel and root hypoplasia * Iron Age (La Tène period) * Middle Ages Subject RIV: AC - Archeology, Anthropology, Ethnology http://www.iansa.eu/papers/IANSA-2014-02-kysely.pdf

  2. Structural and optical investigations of oxygen defects in zinc oxide nanoparticles

    International Nuclear Information System (INIS)

    Sahai, Anshuman; Goswami, Navendu

    2015-01-01

    ZnO nanoparticles (NPs) were prepared implementing chemical precipitation method. Structural and optical characterizations of synthesized ZnO NPs were thoroughly probed applying X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), UV- Visible absorption and fluorescence (FL) spectroscopy. The XRD and TEM analyses revealed hexagonal wurtzite phase with 25-30 nm size. EDX analysis indicated oxygen (O) rich composition of nanoparticles. In accordance with EDX, XPS analysis verifies O i rich stoichiometry of prepared NPs. Furthermore, concurrence of lattice oxygen (O L ), interstitial oxygen (O i ) and oxygen vacancy (V O ) in ZnO NPs was demonstrated through XPS analysis. Size quantization of nanoparticles is evident by blue shift of UV-Visible absorption energy. The FL spectroscopic investigations ascertain the existence of several discrete and defect states and radiative transitions occurring therein. Display of visible emission from oxygen defect states and most importantly, excess of O i defects in prepared ZnO nanoparticles, was well established through FL study

  3. Tuning the reactivity of Ru nanoparticles by defect engineering of the reduced graphene oxide support

    KAUST Repository

    Liu, Xin; Sui, Yanhui; Meng, Changgong; Han, Yu

    2014-01-01

    We systematically investigated the electronic structure of Ru nanoparticles supported on various local structures on reduced graphene oxide (rGO) by first-principles-based calculations. We showed that Ru nanoparticles prefer to nucleate

  4. Short-term and long-term effects of transient exogenous cortisol manipulation on oxidative stress in juvenile brown trout

    DEFF Research Database (Denmark)

    Birnie-Gauvin, Kim; Peiman, Kathryn S.; Larsen, Martin Hage

    2017-01-01

    available for physiological functions like defence against oxidative stress. Using brown trout (Salmo trutta), we evaluated the short-term (2 weeks) and long-term (4 months over winter) effects of exogenous cortisol manipulations (versus relevant shams and controls) on the oxidative status of wild juveniles...

  5. Short exposure to acetylene to distinguish between nitrifier and denitrifier nitrous oxide production in soil and sediment samples

    OpenAIRE

    Kester, R.A.; Boer, W. de; Laanbroek, H.J.

    1996-01-01

    The contribution of nitrifiers and denitrifiers to the nitrous oxide production in slurries of calcareous silt loam and river bank sediment at different oxygen concentrations was determined using acetylene as nitrification inhibitor. The addition of 10 Pa acetylene resulted in inhibition of nitrous oxide production at oxic conditions, but strongly enhanced the nitrous oxide production at oxygen-poor and anoxic conditions. Inhibition of nitrification by short exposure (1 to 24 h) to high conce...

  6. Identification of vacancy defect complexes in transparent semiconducting oxides ZnO, In2O3 and SnO2

    International Nuclear Information System (INIS)

    Makkonen, Ilja; Korhonen, Esa; Prozheeva, Vera; Tuomisto, Filip

    2016-01-01

    Positron annihilation spectroscopy, when combined with supporting high-quality modeling of positron states and annihilation in matter, is a powerful tool for detailed defect identification of vacancy-type defects in semiconductors and oxides. Here we demonstrate that the Doppler broadening of the positron annihilation radiation is a very sensitive means for observing the oxygen environment around cation vacancies, the main open-volume defects trapping positrons in measurements made for transparent semiconducting oxides. Changes in the positron annihilation signal due to external manipulation such as irradiation and annealing can be correlated with the associated changes in the sizes of the detected vacancy clusters. Our examples for ZnO, In 2 O 3 and SnO 2 demonstrate that oxygen vacancies in oxides can be detected directly using positron annihilation spectroscopy when they are complexed with cation vacancies. (paper)

  7. Identification of vacancy defect complexes in transparent semiconducting oxides ZnO, In2O3 and SnO2

    Science.gov (United States)

    Makkonen, Ilja; Korhonen, Esa; Prozheeva, Vera; Tuomisto, Filip

    2016-06-01

    Positron annihilation spectroscopy, when combined with supporting high-quality modeling of positron states and annihilation in matter, is a powerful tool for detailed defect identification of vacancy-type defects in semiconductors and oxides. Here we demonstrate that the Doppler broadening of the positron annihilation radiation is a very sensitive means for observing the oxygen environment around cation vacancies, the main open-volume defects trapping positrons in measurements made for transparent semiconducting oxides. Changes in the positron annihilation signal due to external manipulation such as irradiation and annealing can be correlated with the associated changes in the sizes of the detected vacancy clusters. Our examples for ZnO, In2O3 and SnO2 demonstrate that oxygen vacancies in oxides can be detected directly using positron annihilation spectroscopy when they are complexed with cation vacancies.

  8. Metabolic encephalopathy and lipid storage myopathy associated with a presumptive mitochondrial fatty acid oxidation defect in a dog

    Directory of Open Access Journals (Sweden)

    Vanessa R Biegen

    2015-11-01

    Full Text Available A 1-year-old spayed female Shih Tzu presented for episodic abnormalities of posture and mentation. Neurologic examination was consistent with a bilaterally symmetric multifocal encephalopathy. The dog had a waxing-and-waning hyperlactemia and hypoglycemia. Magnetic resonance imaging revealed bilaterally symmetric cavitated lesions of the caudate nuclei with less severe abnormalities in the cerebellar nuclei. Empirical therapy was unsuccessful and the patient was euthanized. Post-mortem histopathology revealed bilaterally symmetric necrotic lesions of the caudate and cerebellar nuclei and multi-organ lipid accumulation, including a lipid storage myopathy. Malonic aciduria and ketonuria were found on urinary organic acid screen. Plasma acylcarnitine analysis suggested a fatty acid oxidation defect. Fatty acid oxidation disorders are inborn errors of metabolism documented in humans, but poorly described in dogs. Although neurologic signs have been described in humans with this group of diseases, descriptions of advanced imaging and histopathology are severely lacking. This report suggests that abnormalities of fatty acid metabolism may cause severe, bilateral gray matter necrosis and lipid accumulation in multiple organs including the skeletal muscles, liver, and kidneys. Veterinarians should be aware that fatty acid oxidation disorders, although potentially fatal, may be treatable. A timely definitive diagnosis is essential in guiding therapy.

  9. Defect-driven interfacial electronic structures at an organic/metal-oxide semiconductor heterojunction.

    Science.gov (United States)

    Winget, Paul; Schirra, Laura K; Cornil, David; Li, Hong; Coropceanu, Veaceslav; Ndione, Paul F; Sigdel, Ajaya K; Ginley, David S; Berry, Joseph J; Shim, Jaewon; Kim, Hyungchui; Kippelen, Bernard; Brédas, Jean-Luc; Monti, Oliver L A

    2014-07-16

    The electronic structure of the hybrid interface between ZnO and the prototypical organic semiconductor PTCDI is investigated via a combination of ultraviolet and X-ray photoelectron spectroscopy (UPS/XPS) and density functional theory (DFT) calculations. The interfacial electronic interactions lead to a large interface dipole due to substantial charge transfer from ZnO to 3,4,9,10-perylenetetracarboxylicdiimide (PTCDI), which can be properly described only when accounting for surface defects that confer ZnO its n-type properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Densification of Highly Defective Ceria by High Temperature Controlled Re-Oxidation

    DEFF Research Database (Denmark)

    Ni, De Wei; Glasscock, Julie; Pons, Aénor

    2014-01-01

    Highly enhanced densification and grain growth of Ce0.9Gd0.1O1.95-δ (CGO, gadolinium-doped ceria, with 10 mol% Gd) is achieved in low oxygen activity atmospheres. However, the material can suffer mechanical failures during cooling when the re-oxidation process is not controlled due to the large...... volume changes. In this work, the redox process of CGO is investigated using dilatometry, microscopy, electrochemical impedance spectroscopy and thermodynamic analysis. In addition, the conditions allowing controlled re-oxidation and cooling in order to preserve the mechanical integrity of the CGO...... component are defined: this can be achieved over a wide temperature range (800−1200◦C) by gradually increasing the oxygen content of the atmosphere. It is found that the electrical conductivity of the CGO, particularly at low temperature (oxidation...

  11. Oxidative stress and myocardial dysfunction in young rabbits after short term anabolic steroids administration.

    Science.gov (United States)

    Germanakis, Ioannis; Tsarouhas, Konstantinos; Fragkiadaki, Persefoni; Tsitsimpikou, Christina; Goutzourelas, Nikolaos; Champsas, Maria Christakis; Stagos, Demetrios; Rentoukas, Elias; Tsatsakis, Aristidis M

    2013-11-01

    The present study focuses on the short term effects of repeated low level administration of turinabol and methanabol on cardiac function in young rabbits (4 months-old). The experimental scheme consisted of two oral administration periods, lasting 1 month each, interrupted by 1-month wash-out period. Serial echocardiographic evaluation at the end of all three experimental periods was performed in all animals. Oxidative stress markers have also been monitored at the end of each administration period. Treated animals originally showed significantly increased myocardial mass and systolic cardiac output, which normalized at the end of the wash out period. Re-administration led to increased cardiac output, at the cost though of a progressive myocardial mass reduction. A dose-dependent trend towards impaired longitudinal systolic, diastolic and global myocardial function was also observed. The adverse effects were more pronounced in the methanabol group. For both anabolic steroids studied, the low dose had no significant effects on oxidative stress markers monitored, while the high dose created a hostile oxidative environment. In conclusion, anabolic administration has been found to create a possible deleterious long term effect on the growth of the immature heart and should be strongly discouraged especially in young human subjects. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Positron annihilation spectroscopic characterization of defects in wide band gap oxide semiconductors

    Science.gov (United States)

    Sarkar, A.; Luitel, Homnath; Gogurla, N.; Sanyal, D.

    2017-03-01

    Annealing effect of granular ZnO has been studied by Doppler broadened electron positron annihilated γ-ray (0.511 MeV) line shape measurement. Ratio curve analysis shows that granular ZnO samples contain both Zn and O vacancies. Such defects exist as agglomerates of several vacancies and start to recover above 400 °C annealing. It has also been observed that due to annealing temperature difference of 125 °C (from 325 °C to 450 °C), huge change occurs in low temperature photoluminescence (PL) of ZnO. Significant reduction of free to bound (FB) transition ~3.315 eV is observed for increasing the annealing temperature. It has been conjectured that ~3.315 eV PL in ZnO is related to particular decoration (unknown) of both Zn and O vacancies. The methodology of revealing defect-property correlation as employed here can also be applied to other types of semiconductors.

  13. Comparison of defects in crystalline oxide semiconductor materials by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Tokiyoshi, E-mail: toki@rins.ryukoku.ac.jp; Kimura, Mutsumi [Department of Electronics and Informatics, Faculty of Science and Technology, Ryukoku University, 1-438, 1-5 Yokotani, Seta Oe-Cho, Otsu, Shiga 520-2194, Japan and Joint Research Center for Science and Technology, Ryukoku University, 1-5 Yokotani, Seta Oe-Cho, Otsu, Shiga 520-2194 (Japan)

    2015-03-15

    Defects in crystalline InGaZnO{sub 4} (IGZO) induced by plasma were investigated using electron spin resonance (ESR). Thermal stabilities and g factors of two ESR signals (A and B observed at g = 1.939 and 2.003, respectively) in IGZO were different from those of the ESR signals observed in component materials such as Ga{sub 2}O{sub 3} (signal observed at g = 1.969), In{sub 2}O{sub 3} (no signal), and ZnO (signal observed at g = 1.957). Signal A in IGZO increased upon annealing at 300 °C for 1 h, but decreased when annealing was continued for more than 2 h. On the other hand, signal B decreased upon annealing at 300 °C for 1 h. The ESR signal in ZnO decayed in accordance with a second-order decay model with a rate constant of 2.1 × 10{sup −4} s{sup −1}; however, this phenomenon was not observed in other materials. This difference might have been due to randomly formed IGZO lattices such as asymmetrical (Ga, Zn)O and In-O layers. Defects in signals A and B in IGZO were formed in trap states (at the deep level) and tail states, respectively.

  14. Comparison of defects in crystalline oxide semiconductor materials by electron spin resonance

    International Nuclear Information System (INIS)

    Matsuda, Tokiyoshi; Kimura, Mutsumi

    2015-01-01

    Defects in crystalline InGaZnO 4 (IGZO) induced by plasma were investigated using electron spin resonance (ESR). Thermal stabilities and g factors of two ESR signals (A and B observed at g = 1.939 and 2.003, respectively) in IGZO were different from those of the ESR signals observed in component materials such as Ga 2 O 3 (signal observed at g = 1.969), In 2 O 3 (no signal), and ZnO (signal observed at g = 1.957). Signal A in IGZO increased upon annealing at 300 °C for 1 h, but decreased when annealing was continued for more than 2 h. On the other hand, signal B decreased upon annealing at 300 °C for 1 h. The ESR signal in ZnO decayed in accordance with a second-order decay model with a rate constant of 2.1 × 10 −4 s −1 ; however, this phenomenon was not observed in other materials. This difference might have been due to randomly formed IGZO lattices such as asymmetrical (Ga, Zn)O and In-O layers. Defects in signals A and B in IGZO were formed in trap states (at the deep level) and tail states, respectively

  15. Ab initio Defect Energetics in LaBO3 Perovskite Solid Oxide Fuel Cell Materials

    DEFF Research Database (Denmark)

    Lee, Yueh-Lin; Morgan, Dane; Kleis, Jesper

    2009-01-01

    Perovskite materials of the form ABO3 are a promising family of compounds for use in solid oxide fuel cell (SOFC) cathodes. Study of the physics of these compounds under SOFC conditions with ab initio methods is particularly challenging due to high temperatures, exchange of oxygen with O2 gas...

  16. Indium–gallium–zinc oxide thin film transistors with a hybrid-channel structure for defect suppression and mobility improvement

    International Nuclear Information System (INIS)

    Lin, Huang-Kai; Su, Liang-Yu; Hung, Chia-Chin; Huang, JianJang

    2013-01-01

    In this work, we explore an indium gallium zinc oxide (IGZO) thin film transistor structure with a vacuum annealed IGZO thin film inserted between the dielectric and typical channel layers. The device demonstrates a better subthreshold swing and field-effect mobility due to the suppression of defects in the channel and the channel/dielectric interface. The hybrid channel structure also exhibits the flexibility of adjusting the threshold voltage. The superior carrier mobility was then verified from the transient response of the inverter circuit constructed by the devices. - Highlights: • Additional in-situ annealed In–Ga–ZnO film was inserted in thin film transistor (TFT). • Traps are suppressed and field effect mobility is improved in the TFT. • An inverter with the device structure has a better transient response

  17. Indium–gallium–zinc oxide thin film transistors with a hybrid-channel structure for defect suppression and mobility improvement

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Huang-Kai; Su, Liang-Yu; Hung, Chia-Chin [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 1, Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China); Huang, JianJang, E-mail: jjhuang@cc.ee.ntu.edu.tw [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 1, Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China); Department of Electrical Engineering, National Taiwan University, 1, Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China)

    2013-07-01

    In this work, we explore an indium gallium zinc oxide (IGZO) thin film transistor structure with a vacuum annealed IGZO thin film inserted between the dielectric and typical channel layers. The device demonstrates a better subthreshold swing and field-effect mobility due to the suppression of defects in the channel and the channel/dielectric interface. The hybrid channel structure also exhibits the flexibility of adjusting the threshold voltage. The superior carrier mobility was then verified from the transient response of the inverter circuit constructed by the devices. - Highlights: • Additional in-situ annealed In–Ga–ZnO film was inserted in thin film transistor (TFT). • Traps are suppressed and field effect mobility is improved in the TFT. • An inverter with the device structure has a better transient response.

  18. The role of surface and deep-level defects on the emission of tin oxide quantum dots

    International Nuclear Information System (INIS)

    Kumar, Vinod; Kumar, Vijay; Som, S; Ntwaeaborwa, O M; Swart, H C; Neethling, J H; Lee, Mike

    2014-01-01

    This paper reports on the role of surface and deep-level defects on the blue emission of tin oxide quantum dots (SnO 2 QDs) synthesized by the solution-combustion method at different combustion temperatures. X-ray diffraction studies showed the formation of a single rutile SnO 2 phase with a tetragonal lattice structure. High resolution transmission electron microscopy studies revealed an increase in the average dot size from 2.2 to 3.6 nm with an increase of the combustion temperature from 350 to 550 °C. A decrease in the band gap value from 3.37 to 2.76 eV was observed with the increase in dot size due to the quantum confinement effect. The photoluminescence emission was measured for excitation at 325 nm and it showed a broad blue emission band for all the combustion temperatures studied. This was due to the creation of various oxygen and tin vacancies/defects as confirmed by x-ray photoelectron spectroscopy data. The origin of the blue emission in the SnO 2 QDs is discussed with the help of an energy band diagram. (paper)

  19. Probing and Manipulating the Interfacial Defects of InGaAs Dual-Layer Metal Oxides at the Atomic Scale.

    Science.gov (United States)

    Wu, Xing; Luo, Chen; Hao, Peng; Sun, Tao; Wang, Runsheng; Wang, Chaolun; Hu, Zhigao; Li, Yawei; Zhang, Jian; Bersuker, Gennadi; Sun, Litao; Pey, Kinleong

    2018-01-01

    The interface between III-V and metal-oxide-semiconductor materials plays a central role in the operation of high-speed electronic devices, such as transistors and light-emitting diodes. The high-speed property gives the light-emitting diodes a high response speed and low dark current, and they are widely used in communications, infrared remote sensing, optical detection, and other fields. The rational design of high-performance devices requires a detailed understanding of the electronic structure at this interface; however, this understanding remains a challenge, given the complex nature of surface interactions and the dynamic relationship between the morphology evolution and electronic structures. Herein, in situ transmission electron microscopy is used to probe and manipulate the structural and electrical properties of ZrO 2 films on Al 2 O 3 and InGaAs substrate at the atomic scale. Interfacial defects resulting from the spillover of the oxygen-atom conduction-band wavefunctions are resolved. This study unearths the fundamental defect-driven interfacial electric structure of III-V semiconductor materials and paves the way to future high-speed and high-reliability devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Modeling of Semiconductors and Correlated Oxides with Point Defects by First Principles Methods

    KAUST Repository

    Wang, Hao

    2014-06-15

    Point defects in silicon, vanadium dioxide, and doped ceria are investigated by density functional theory. Defects involving vacancies and interstitial oxygen and carbon in silicon are after formed in outer space and significantly affect device performances. The screened hybrid functional by Heyd-Scuseria-Ernzerhof is used to calculate formation energies, binding energies, and electronic structures of the defective systems because standard density functional theory underestimates the bang gap of silicon. The results indicate for the A-center a −2 charge state. Tin is proposed to be an effective dopant to suppress the formation of A-centers. For the total energy difference between the A- and B-type carbon related G-centers we find close agreement with the experiment. The results indicate that the C-type G-center is more stable than both the A- and B-types. The electronic structures of the monoclinic and rutile phases of vanadium dioxide are also studied using the Heyd-Scuseria-Ernzerhof functional. The ground states of the pure phases obtained by calculations including spin polarization disagree with the experimental observations that the monoclinic phase should not be magnetic, the rutile phase should be metallic, and the monoclinic phase should have a lower total energy than the rutile phase. By tuning the Hartree-Fock fraction α to 10% the agreement with experiments is improved in terms of band gaps and relative energies of the phases. A calculation scheme is proposed to simulate the relationship between the transition temperature of the metal-insulator transition and the dopant concentration in tungsten doped vanadium dioxide. We achieve good agreement with the experimental situation. 18.75% and 25% yttrium, lanthanum, praseodymium, samarium, and gadolinium doped ceria supercells generated by the special quasirandom structure approach are employed to investigate the impact of doping on the O diffusion. The experimental behavior of the conductivity for the

  1. Modeling of Semiconductors and Correlated Oxides with Point Defects by First Principles Methods

    KAUST Repository

    Wang, Hao

    2014-01-01

    Point defects in silicon, vanadium dioxide, and doped ceria are investigated by density functional theory. Defects involving vacancies and interstitial oxygen and carbon in silicon are after formed in outer space and significantly affect device performances. The screened hybrid functional by Heyd-Scuseria-Ernzerhof is used to calculate formation energies, binding energies, and electronic structures of the defective systems because standard density functional theory underestimates the bang gap of silicon. The results indicate for the A-center a −2 charge state. Tin is proposed to be an effective dopant to suppress the formation of A-centers. For the total energy difference between the A- and B-type carbon related G-centers we find close agreement with the experiment. The results indicate that the C-type G-center is more stable than both the A- and B-types. The electronic structures of the monoclinic and rutile phases of vanadium dioxide are also studied using the Heyd-Scuseria-Ernzerhof functional. The ground states of the pure phases obtained by calculations including spin polarization disagree with the experimental observations that the monoclinic phase should not be magnetic, the rutile phase should be metallic, and the monoclinic phase should have a lower total energy than the rutile phase. By tuning the Hartree-Fock fraction α to 10% the agreement with experiments is improved in terms of band gaps and relative energies of the phases. A calculation scheme is proposed to simulate the relationship between the transition temperature of the metal-insulator transition and the dopant concentration in tungsten doped vanadium dioxide. We achieve good agreement with the experimental situation. 18.75% and 25% yttrium, lanthanum, praseodymium, samarium, and gadolinium doped ceria supercells generated by the special quasirandom structure approach are employed to investigate the impact of doping on the O diffusion. The experimental behavior of the conductivity for the

  2. THYROID HORMONE REVERSES AGING-INDUCED MYOCARDIAL FATTY ACID OXIDATION DEFECTS AND IMPROVES THE RESPONSE TO ACUTELY INCREASED AFTERLOAD

    Energy Technology Data Exchange (ETDEWEB)

    Ledee, Dolena; Portman, Michael A.; Kajimoto, Masaki; Isern, Nancy G.; Olson, Aaron

    2013-06-07

    Background: Subclinical hypothyroidism occurs during aging in humans and mice and may contribute to development of heart failure. Aging also impairs myocardial fatty acid oxidation, causing increased reliance on flux through pyruvate dehydrogenase (PDH) to maintain function. We hypothesize that the metabolic changes in aged hearts make them less tolerant to acutely increased work and that thyroid hormone reverses these defects. Methods: Studies were performed on young (Young, 4-6 months) and aged (Old, 22-24 months) C57/BL6 mice at standard (50 mmHg) and high afterload (80 mmHg). Another aged group received thyroid hormone for 3 weeks (Old-TH, high afterload only). Function was measured in isolated working hearts along with substrate fractional contributions (Fc) to the citric acid cycle (CAC) using perfusate with 13C labeled lactate, pyruvate, glucose and unlabeled palmitate and insulin. Results: Cardiac function was similar between Young and Old mice at standard afterload. Palmitate Fc was reduced but no individual carbohydrate contributions differed. CAC and individual substrate fluxes decreased in aged. At high afterload, -dP/dT was decreased in Old versus Young. Similar to low afterload, palmitate Fc was decreased in Old. Thyroid hormone reversed aging-induced changes in palmitate Fc and flux while significantly improving cardiac function. Conclusion: The aged heart shows diminished ability to increase cardiac work due to substrate limitations, primarily impaired fatty acid oxidation. The heart accommodates slightly by increasing efficiency through oxidation of carbohydrate substrates. Thyroid hormone supplementation in aged mice significantly improves cardiac function potentially through restoration of fatty acid oxidation.

  3. Short-Term Exposure to Air Pollution and Biomarkers of Oxidative Stress: The Framingham Heart Study.

    Science.gov (United States)

    Li, Wenyuan; Wilker, Elissa H; Dorans, Kirsten S; Rice, Mary B; Schwartz, Joel; Coull, Brent A; Koutrakis, Petros; Gold, Diane R; Keaney, John F; Lin, Honghuang; Vasan, Ramachandran S; Benjamin, Emelia J; Mittleman, Murray A

    2016-04-28

    Short-term exposure to elevated air pollution has been associated with higher risk of acute cardiovascular diseases, with systemic oxidative stress induced by air pollution hypothesized as an important underlying mechanism. However, few community-based studies have assessed this association. Two thousand thirty-five Framingham Offspring Cohort participants living within 50 km of the Harvard Boston Supersite who were not current smokers were included. We assessed circulating biomarkers of oxidative stress including blood myeloperoxidase at the seventh examination (1998-2001) and urinary creatinine-indexed 8-epi-prostaglandin F2α (8-epi-PGF2α) at the seventh and eighth (2005-2008) examinations. We measured fine particulate matter (PM2.5), black carbon, sulfate, nitrogen oxides, and ozone at the Supersite and calculated 1-, 2-, 3-, 5-, and 7-day moving averages of each pollutant. Measured myeloperoxidase and 8-epi-PGF2α were loge transformed. We used linear regression models and linear mixed-effects models with random intercepts for myeloperoxidase and indexed 8-epi-PGF2α, respectively. Models were adjusted for demographic variables, individual- and area-level measures of socioeconomic position, clinical and lifestyle factors, weather, and temporal trend. We found positive associations of PM2.5 and black carbon with myeloperoxidase across multiple moving averages. Additionally, 2- to 7-day moving averages of PM2.5 and sulfate were consistently positively associated with 8-epi-PGF2α. Stronger positive associations of black carbon and sulfate with myeloperoxidase were observed among participants with diabetes than in those without. Our community-based investigation supports an association of select markers of ambient air pollution with circulating biomarkers of oxidative stress. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  4. Analysis of the oxidation of short chain alkynes by flavocytochrome P450 BM3.

    Science.gov (United States)

    Waltham, Timothy N; Girvan, Hazel M; Butler, Christopher F; Rigby, Stuart R; Dunford, Adrian J; Holt, Robert A; Munro, Andrew W

    2011-04-01

    Bacillus megaterium flavocytochrome P450 BM3 (BM3) is a high activity fatty acid hydroxylase, formed by the fusion of soluble cytochrome P450 and cytochrome P450 reductase modules. Short chain (C6, C8) alkynes were shown to be substrates for BM3, with productive outcomes (i.e. alkyne hydroxylation) dependent on position of the carbon-carbon triple bond in the molecule. Wild-type P450 BM3 catalyses ω-3 hydroxylation of both 1-hexyne and 1-octyne, but is suicidally inactivated in NADPH-dependent turnover with non-terminal alkynes. A F87G mutant of P450 BM3 also undergoes turnover-dependent heme destruction with the terminal alkynes, pointing to a key role for Phe87 in controlling regioselectivity of alkyne oxidation. The terminal alkynes access the BM3 heme active site led by the acetylene functional group, since hydroxylated products are not observed near the opposite end of the molecules. For both 1-hexyne and 1-octyne, the predominant enantiomeric product formed (up to ∼90%) is the (S)-(-)-1-alkyn-3-ol form. Wild-type P450 BM3 is shown to be an effective oxidase catalyst of terminal alkynes, with strict regioselectivity of oxidation and potential biotechnological applications. The absence of measurable octanoic or hexanoic acid products from oxidation of the relevant 1-alkynes is also consistent with previous studies suggesting that removal of the phenyl group in the F87G mutant does not lead to significant levels of ω-oxidation of alkyl chain substrates.

  5. Physicochemical characterization of point defects in fluorine doped tin oxide films

    Science.gov (United States)

    Akkad, Fikry El; Joseph, Sudeep

    2012-07-01

    The physical and chemical properties of spray deposited FTO films are studied using FESEM, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), electrical and optical measurements. The results of XRD measurements showed that the films are polycrystalline (grain size 20-50 nm) with Rutile structure and mixed preferred orientation along the (200) and (110) planes. An angular shift of the XRD peaks after F-doping is observed and interpreted as being due to the formation of substitutional fluorine defects (FO) in presence of high concentration of oxygen vacancies (VO) that are electrically neutral. The electrical neutrality of oxygen vacancies is supported by the observation that the electron concentration n is two orders of magnitude lower than the VO concentration calculated from chemical analyses using XPS measurements. It is shown that an agreement between XPS, XRD, and Hall effect results is possible provided that the degree of deviation from stoichiometry is calculated with the assumption that the major part of the bulk carbon content is involved in O-C bonds. High temperature thermal annealing is found to cause an increase in the FO concentration and a decrease in both n and VO concentrations with the increase of the annealing temperature. These results could be interpreted in terms of a high temperature chemical exchange reaction between the SnO2 matrix and a precipitated fluoride phase. In this reaction, fluorine is released to the matrix and Sn is trapped by the fluoride phase, thus creating substitutional fluorine FO and tin vacancy VSn defects. The enthalpy of this reaction is determined to be approximately 2.4 eV while the energy of formation of a VSn through the migration of SnSn host atom to the fluoride phase is approximately 0.45 eV.

  6. High Performance Nano-Crystalline Oxide Fuel Cell Materials. Defects, Structures, Interfaces, Transport, and Electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, Scott [Northwestern Univ., Evanston, IL (United States); Poeppelmeier, Ken [Northwestern Univ., Evanston, IL (United States); Mason, Tom [Northwestern Univ., Evanston, IL (United States); Marks, Lawrence [Northwestern Univ., Evanston, IL (United States); Voorhees, Peter [Northwestern Univ., Evanston, IL (United States)

    2016-09-07

    This project addresses fundamental materials challenges in solid oxide electrochemical cells, devices that have a broad range of important energy applications. Although nano-scale mixed ionically and electronically conducting (MIEC) materials provide an important opportunity to improve performance and reduce device operating temperature, durability issues threaten to limit their utility and have remained largely unexplored. Our work has focused on both (1) understanding the fundamental processes related to oxygen transport and surface-vapor reactions in nano-scale MIEC materials, and (2) determining and understanding the key factors that control their long-term stability. Furthermore, materials stability has been explored under the “extreme” conditions encountered in many solid oxide cell applications, i.e, very high or very low effective oxygen pressures, and high current density.

  7. Defects in muscle branched-chain amino acid oxidation contribute to impaired lipid metabolism

    Directory of Open Access Journals (Sweden)

    Carles Lerin

    2016-10-01

    Full Text Available Objective: Plasma levels of branched-chain amino acids (BCAA are consistently elevated in obesity and type 2 diabetes (T2D and can also prospectively predict T2D. However, the role of BCAA in the pathogenesis of insulin resistance and T2D remains unclear. Methods: To identify pathways related to insulin resistance, we performed comprehensive gene expression and metabolomics analyses in skeletal muscle from 41 humans with normal glucose tolerance and 11 with T2D across a range of insulin sensitivity (SI, 0.49 to 14.28. We studied both cultured cells and mice heterozygous for the BCAA enzyme methylmalonyl-CoA mutase (Mut and assessed the effects of altered BCAA flux on lipid and glucose homeostasis. Results: Our data demonstrate perturbed BCAA metabolism and fatty acid oxidation in muscle from insulin resistant humans. Experimental alterations in BCAA flux in cultured cells similarly modulate fatty acid oxidation. Mut heterozygosity in mice alters muscle lipid metabolism in vivo, resulting in increased muscle triglyceride accumulation, increased plasma glucose, hyperinsulinemia, and increased body weight after high-fat feeding. Conclusions: Our data indicate that impaired muscle BCAA catabolism may contribute to the development of insulin resistance by perturbing both amino acid and fatty acid metabolism and suggest that targeting BCAA metabolism may hold promise for prevention or treatment of T2D. Keywords: Insulin sensitivity, BCAA, Fatty acid oxidation, TCA cycle

  8. Point defects and irradiation in oxides: simulations at the atomic scale; Defauts ponctuels et irradiation dans les oxydes: simulation a l'echelle atomique

    Energy Technology Data Exchange (ETDEWEB)

    Crocombette, J.P

    2005-12-15

    The studies done by Jean-Paul Crocombette between 1996 and 2005 in the Service de Recherches de Metallurgie Physique of the Direction de l'Energie Nucleaire in Saclay are presented in this Habilitation thesis. These works were part of the material science researches on the ageing, especially under irradiation, of oxides of interest for the nuclear industry. In this context simulation studies at the atomic scale were performed on two elementary components of ageing under irradiation : point defects and displacement cascades ; using two complementary simulation techniques : ab initio electronic structure calculations and empirical potential molecular dynamics. The first part deals with point defects : self defects (vacancies or interstitials) or hetero-atomic dopants. One first recalls the energetics of such defects in oxides, the specific features of defects calculations and the expected accuracy of these calculations. Then one presents the results obtained on uranium dioxide, oxygen in silver and amorphous silica. The second part tackles the modelling of disintegration recoil nuclei in various?displacement cascades created by crystalline matrices for actinide waste disposal. Cascade calculations give access to the amorphization mechanisms under irradiation of these materials. One thus predicts that the amorphization in zircon takes place directly in the tracks whereas in lanthanum zirconate, the amorphization proceeds through the accumulation of point defects. Finally the prospects of these studies are discussed. (author)

  9. Generation of highly N-type, defect passivated transition metal oxides using plasma fluorine insertion

    Science.gov (United States)

    Baker, L. Robert; Seo, Hyungtak; Hervier, Antoine; Somorjai, Gabor A.

    2016-04-12

    A new composition of matter is disclosed wherein oxygen vacancies in a semiconducting transition metal oxide such as titanium dioxide are filled with a halogen such as Fluorine, whereby the conductivity of the composition is greatly enhanced, while at the same time the chemical stability of the composition is greatly improved. Stoichiometric titanium dioxide having less than 3 % oxygen vacancies is subject to fluorine insertion such that oxygen vacancies are filled, limited amounts of fluorine replace additional oxygen atoms and fluorine interstitially inserts into the body of the TiO.sub.2 composition.

  10. Impact of short-term dietary modification on postprandial oxidative stress

    Directory of Open Access Journals (Sweden)

    Bloomer Richard J

    2012-03-01

    Full Text Available Abstract Background We have recently reported that short-term (21-day dietary modification in accordance with a stringent vegan diet (i.e., a Daniel Fast lowers blood lipids as well as biomarkers of oxidative stress. However, this work only involved measurements obtained in a fasted state. In the present study, we determined the postprandial response to a high-fat milkshake with regards to blood triglycerides (TAG, biomarkers of oxidative stress, and hemodynamic variables before and following a 21-day Daniel Fast. Methods Twenty-two subjects (10 men and 12 women; aged 35 ± 3 years completed a 21-day Daniel Fast. To induce oxidative stress, a milkshake (fat = 0.8 g·kg-1; carbohydrate = 1.0 g·kg-1; protein = 0.25 g·kg-1 was consumed by subjects on day one and day 22 in a rested and 12-hour fasted state. Before and at 2 and 4 h after consumption of the milkshake, heart rate (HR and blood pressure were measured. Blood samples were also collected at these times and analyzed for TAG, malondialdehyde (MDA, hydrogen peroxide (H2O2, advanced oxidation protein products (AOPP, nitrate/nitrite (NOx, and Trolox Equivalent Antioxidant Capacity (TEAC. Results A time effect was noted for HR (p = 0.006, with values higher at 2 hr post intake of the milkshake as compared to pre intake (p p = 0.02, and a trend for lower systolic blood pressure was noted (p = 0.07. Time effects were noted for TAG (p = 0.001, MDA (p 2O2 (p p p p p = 0.02, which was higher post fast as compared to pre fast. No pre/post fast × time interactions were noted (p > 0.05, with the area under the curve from pre to post fast reduced only slightly for TAG (11%, MDA (11%, H2O2 (8%, and AOPP (12%, with a 37% increase noted for NOx. Conclusion Partaking in a 21-day Daniel Fast does not result in a statistically significant reduction in postprandial oxidative stress. It is possible that a longer time course of adherence to the Daniel Fast eating plan may be needed to observe significant

  11. Ion implantation-induced defects in Oxide Dispersion Strengthened (ODS) steel probed by positron annihilation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Anwand, Wolfgang; Butterling, Maik; Brauer, Gerhard; Wagner, Andreas [HZDR, Institut fuer Strahlenphysik (Germany); Richter, Astrid [Technische Hochschule Wildau (Germany); Koegler, Reinhard [HZDR, Institut fuer Ionenstrahlphysik und Materialforschung (Germany); Chen, C.L. [I-Shou University, Kaohsiung (China)

    2012-07-01

    ODS steel is a promising candidate for an application in fission and fusion power plants of a new generation because of its advantageous properties as stability and temperature resistance. A microscopic understanding of the physical reasons of the mechanical and thermal properties as well as the behaviour of the material under irradiation is an important pre-condition for such applications. The investigated ODS FeCrAl alloy *PM2000* has been produced in a powder metallurgical way. Neutron-induced damage at ODS steel was simulated by He{sup +} and Fe{sup 2+} co-implantation with energies of 2.5 MeV and 400 keV, respectively, and different fluences. The implantation has been carried out with a dual ion beam which enables a simultaneous implantation of both ion types. Thereby the Fe{sup 2+} implantation was used for the creation of radiation defects, and He{sup +} was implanted in order to reproduce He bubbles as they are expected to appear by neutron irradiation. The implantation-induced damage was investigated by depth dependent Doppler broadening measurements using a variable energy slow positron beam.

  12. Emission channeling with short-lived isotopes lattice location of impurities in semiconductors and oxides

    CERN Multimedia

    We propose to perform emission channeling lattice location experiments in a number of semiconductor and oxide systems of technological relevance: \\\\- The lattice location of the transition metal probes $^{56}$Mn ($\\textit{t}_{1/2}$=2.6 h), $^{59}$Fe (45 d), $^{61}$Co (1.6 h) and $^{65}$Ni (2.5 h) is to be investigated in materials of interest as dilute magnetic semiconductors, such as GaMnAs, GaMnN, GaFeN, AlGaN, SiC, and in a number of oxides that are candidates for “single ion ferromagnetism”, in particular SrTiO$_3$ and LiNbO$_3$.\\\\- The topic of $\\textit{p}$-type doping of nitride semiconductors shall be addressed by studying the lattice sites of the acceptor dopants Mg and Be in GaN and AlN using the short-lived probes $^{27}$Mg (9.5 min) and $^{11}$Be (13.8 s). The aim is to reach a lattice location precision around 0.05 Å in order to provide critical tests for recent theoretical models which e.g. have predicted displacements of the Mg atom from the ideal substitutional Ga and Al sites of the order...

  13. Oxidative stress in duckweed (Lemna minor L.) caused by short-term cadmium exposure

    Energy Technology Data Exchange (ETDEWEB)

    Razinger, Jaka [Department for Environmental Technologies and Biomonitoring, Institute of Physical Biology, Veliko Mlacevo 59, SI-1290 Grosuplje (Slovenia)], E-mail: jaka@ifb.si; Dermastia, Marina [National Institute of Biology, Vecna pot 111, p.p. 141, SI-1001 Ljubljana (Slovenia); Biotechnical Faculty, Department of Biology, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia); Koce, Jasna Dolenc [Biotechnical Faculty, Department of Biology, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia); Zrimec, Alexis [Department for Environmental Technologies and Biomonitoring, Institute of Physical Biology, Veliko Mlacevo 59, SI-1290 Grosuplje (Slovenia)

    2008-06-15

    The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna minor L. (common duckweed) to concentrations of CdCl{sub 2} ranging from 0 to 500 {mu}M. High accumulation of cadmium was observed (12,320 {+-} 2155 {mu}g g{sup -1} at 500 {mu}M CdCl{sub 2}), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence. Total glutathione concentration decreased significantly; however, the concentration of oxidized glutathione remained stable. The responses of four antioxidant enzymes showed that catalase was the most inhibited after CdCl{sub 2} exposure, ascorbate peroxidase and guaiacol peroxidase moderately, and glutathione reductase least. The total antioxidative potential revealed an induced antioxidative network at 0.1 {mu}M CdCl{sub 2} (137 {+-} 13.2% of the control) and its reduction to only 47.4 {+-} 4.0% of the control at higher cadmium concentrations. The possible application of the examined biomarkers in ecotoxicological research is discussed. - The increase of total antioxidative potential at low cadmium concentration is one of the mechanisms that helps duckweed to cope with cadmium-induced oxidative stress.

  14. Oxidative stress in duckweed (Lemna minor L.) caused by short-term cadmium exposure

    International Nuclear Information System (INIS)

    Razinger, Jaka; Dermastia, Marina; Koce, Jasna Dolenc; Zrimec, Alexis

    2008-01-01

    The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna minor L. (common duckweed) to concentrations of CdCl 2 ranging from 0 to 500 μM. High accumulation of cadmium was observed (12,320 ± 2155 μg g -1 at 500 μM CdCl 2 ), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence. Total glutathione concentration decreased significantly; however, the concentration of oxidized glutathione remained stable. The responses of four antioxidant enzymes showed that catalase was the most inhibited after CdCl 2 exposure, ascorbate peroxidase and guaiacol peroxidase moderately, and glutathione reductase least. The total antioxidative potential revealed an induced antioxidative network at 0.1 μM CdCl 2 (137 ± 13.2% of the control) and its reduction to only 47.4 ± 4.0% of the control at higher cadmium concentrations. The possible application of the examined biomarkers in ecotoxicological research is discussed. - The increase of total antioxidative potential at low cadmium concentration is one of the mechanisms that helps duckweed to cope with cadmium-induced oxidative stress

  15. Dissolution behavior of irradiated mixed oxide fuel with short stroke shearing for fast reactor reprocessing

    International Nuclear Information System (INIS)

    Ikeuchi, Hirotomo; Sano, Yuichi; Shibata, Atsuhiro; Koizumi, Tsutomu; Washiya, Tadahiro

    2013-01-01

    An efficient dissolution process was established for future reprocessing in which mixed-oxide (MOX) fuels with high plutonium contents and dissolver solution with high heavy-metal (HM) concentrations (more than 500 g dm -3 ) will be treated. This dissolution process involves short stroke shearing of fuels (∼10 mm in length). The dissolution kinetics of irradiated MOX fuels and the effects of the Pu content, HM concentration, and fuel form on the dissolution rate were investigated. Irradiated fuel was found to dissolve as 10 2 -10 3 times fast as non-irradiated fuel, but the rate decreased with increasing Pu content. Kinetic analysis based on the fragmentation model, which considers the penetration and diffusion of nitric acid through fuel matrices prior to chemical reaction, indicated that the dissolution rate of irradiated fuel was affected not only by the volume ratio of liquid to solid (L/S ratio) but also by the exposed surface area per unit mole of nitric acid (A/m ratio). The penetration rate of nitric acid is expected to be decreased at high HM concentrations by a reduction in the L/S ratio, but enhanced by shearing the fuel pieces with short strokes and thus enlarging the A/m ratio. (author)

  16. Proceedings of the European Meeting on Positron Studies of Defects

    International Nuclear Information System (INIS)

    1987-01-01

    The meeting dealt with both theoretical and experimental aspects of positron studies of defects using conventional and novel positron techniques. The subjects are indicated in the following headings: (1) theory of positrons in imperfect solids, (2) vacancies in metals and alloys, (3) dislocation and deformation effects, (4) amorphous alloys and fine-grained materials, (5) phase transitions, (6) precipitation phenomena, (7) gas impurity-defect interaction and irradiation effects, (8) defects in elemental semiconductors, (9) defects in compound semiconductors, (10) slow positron studies of defects, (11) defects in oxides and halides, (12) defects in molecular solids, and (13) advances in experimental techniques and data treatment. Althogether 141 contributions (invited plenary lectures, short lectures, and posters) are presented as titles with abstracts. Most of them are in INIS scope and are processed individually for the database

  17. Fiber optic hydrogen gas sensor utilizing surface plasmon resonance and native defects of zinc oxide by palladium

    International Nuclear Information System (INIS)

    Tabassum, Rana; Gupta, Banshi D

    2016-01-01

    We present an experimental study on a surface plasmon resonance (SPR) based fiber optic hydrogen gas sensor employing a palladium doped zinc oxide nanocomposite (ZnO (1−x) Pd x , 0 ≤ x ≤ 0.85) layer over the silver coated unclad core of the fiber. Palladium doped zinc oxide nanocomposites (ZnO (1−x) Pd x )  are prepared by a chemical route for different composition ratios and their structural, morphological and hydrogen sensing properties are investigated experimentally. The sensing principle involves the absorption of hydrogen gas by ZnO (1−x) Pd x , altering its dielectric function. The change in the dielectric constant is analyzed in terms of the red shift of the resonance wavelength in the visible region of the electromagnetic spectrum. To check the sensing capability of sensing probes fabricated with varying composition ratio (x) of nanocomposite, the SPR curves are recorded typically for 0% H 2 and 4% H 2 in N 2 atmosphere for each fabricated probe. On changing the concentration of hydrogen gas from 0% to 4%, the red shift in the SPR spectrum confirms the change in dielectric constant of ZnO (1−x) Pd x on exposure to hydrogen gas. It is noted that the shift in the SPR spectrum increases monotonically up to a certain fraction of Pd in zinc oxide, beyond which it starts decreasing. SEM images and the photoluminescence (PL) spectra reveal that Pd dopant atoms substitutionally incorporated into the ZnO lattice profoundly affect its defect levels; this is responsible for the optimal composition of ZnO (1−x) Pd x to sense the hydrogen gas. The sensor is highly selective to hydrogen gas and possesses high sensitivity. Since optical fiber sensing technology is employed along with the SPR technique, the present sensor is capable of remote sensing and online monitoring of hydrogen gas. (paper)

  18. Defects in muscle branched-chain amino acid oxidation contribute to impaired lipid metabolism.

    Science.gov (United States)

    Lerin, Carles; Goldfine, Allison B; Boes, Tanner; Liu, Manway; Kasif, Simon; Dreyfuss, Jonathan M; De Sousa-Coelho, Ana Luisa; Daher, Grace; Manoli, Irini; Sysol, Justin R; Isganaitis, Elvira; Jessen, Niels; Goodyear, Laurie J; Beebe, Kirk; Gall, Walt; Venditti, Charles P; Patti, Mary-Elizabeth

    2016-10-01

    Plasma levels of branched-chain amino acids (BCAA) are consistently elevated in obesity and type 2 diabetes (T2D) and can also prospectively predict T2D. However, the role of BCAA in the pathogenesis of insulin resistance and T2D remains unclear. To identify pathways related to insulin resistance, we performed comprehensive gene expression and metabolomics analyses in skeletal muscle from 41 humans with normal glucose tolerance and 11 with T2D across a range of insulin sensitivity (SI, 0.49 to 14.28). We studied both cultured cells and mice heterozygous for the BCAA enzyme methylmalonyl-CoA mutase (Mut) and assessed the effects of altered BCAA flux on lipid and glucose homeostasis. Our data demonstrate perturbed BCAA metabolism and fatty acid oxidation in muscle from insulin resistant humans. Experimental alterations in BCAA flux in cultured cells similarly modulate fatty acid oxidation. Mut heterozygosity in mice alters muscle lipid metabolism in vivo, resulting in increased muscle triglyceride accumulation, increased plasma glucose, hyperinsulinemia, and increased body weight after high-fat feeding. Our data indicate that impaired muscle BCAA catabolism may contribute to the development of insulin resistance by perturbing both amino acid and fatty acid metabolism and suggest that targeting BCAA metabolism may hold promise for prevention or treatment of T2D.

  19. Sodium benzoate induced developmental defects, oxidative stress and anxiety-like behaviour in zebrafish larva.

    Science.gov (United States)

    Gaur, Himanshu; Purushothaman, Srinithi; Pullaguri, Narasimha; Bhargava, Yogesh; Bhargava, Anamika

    2018-05-28

    Sodium benzoate (SB) is a common food preservative. Its FDA described safety limit is 1000 ppm. Lately, increased use of SB has prompted investigations regarding its effects on biological systems. Data regarding toxicity of SB is divergent and controversial with studies reporting both harmful and beneficial effects. Therefore, we did a systematic dose dependent toxicity study of SB using zebrafish vertebrate animal model. We also investigated oxidative stress and anxiety-like behaviour in zebrafish larva treated with SB. Our results indicate that SB induced developmental (delayed hatching), morphological (pericardial edema, yolk sac edema and tail bending), biochemical (oxidative stress) and behavioural (anxiety-like behaviour) abnormalities in developing zebrafish larva. LC 50 of SB induced toxicity was approximately 400 ppm after 48 h of SB exposure. Our study strongly supports its harmful effects on vertebrates at increasing doses. Thus, we suggest caution in the excessive use of this preservative in processed and convenience foods. Copyright © 2018 Elsevier Inc. All rights reserved.

  20. Internal shorting and fuel loss of a low temperature solid oxide fuel cell with SDC electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xinge; Robertson, Mark; Deces-Petit, Cyrille; Qu, Wei; Kesler, Olivera; Maric, Radenka; Ghosh, Dave [Institute for Fuel Cell Innovation, National Research Council Canada, 4250 Wesbrook Mall, Vancouver, BC V6T 1W5 (Canada)

    2007-02-10

    A solid oxide fuel cell with Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9} (SDC) electrolyte of 10 {mu}m in thickness and Ni-SDC anode of 15 {mu}m in thickness on a 0.8 mm thick Ni-YSZ cermet substrate was fabricated by tape casting, screen printing and co-firing. A composite cathode, 75 wt.% Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3} (SSCo) + 25 wt.% SDC, approximately 50 {mu}m in thickness, was printed on the co-fired half-cell, and sintered at 950 C. The cell showed a high electrochemical performance at temperatures ranging from 500 to 650 C. Peak power density of 545 mW cm{sup -2} at 600 C was obtained. However, the cell exhibited severe internal shorting due to the mixed conductivity of the SDC electrolyte. Both the amount of water collected from the anode outlet and the open circuit voltage (OCV) indicated that the internal shorting current could reach 0.85 A cm{sup -2} or more at 600 C. Zr content inclusions were found at the surface and in the cross-section of the SDC electrolyte, which could be one of the reasons for reduced OCV and oxygen ionic conductivity. Fuel loss due to internal shorting of the thin SDC electrolyte cell becomes a significant concern when it is used in applications requiring high fuel utilization and electrical efficiency. (author)

  1. Point defects in solids

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    The principal properties of point defects are studied: thermodynamics, electronic structure, interactions with etended defects, production by irradiation. Some measuring methods are presented: atomic diffusion, spectroscopic methods, diffuse scattering of neutron and X rays, positron annihilation, molecular dynamics. Then points defects in various materials are investigated: ionic crystals, oxides, semiconductor materials, metals, intermetallic compounds, carbides, nitrides [fr

  2. A case of osteomalacia due to deranged mineral balance caused by saccharated ferric oxide and short-bowel syndrome

    Science.gov (United States)

    Nomoto, Hiroshi; Miyoshi, Hideaki; Nakamura, Akinobu; Nagai, So; Kitao, Naoyuki; Shimizu, Chikara; Atsumi, Tatsuya

    2017-01-01

    Abstract Rationale: Saccharated ferric oxide has been shown to lead to elevation of fibroblast growth factor 23, hypophosphatemia, and, consequently, osteomalacia. Moreover, mineral imbalance is often observed in patients with short-bowel syndrome to some degree. Patient concerns: A 62-year-old woman with short-bowel syndrome related with multiple resections of small intestines due to Crohn disease received regular intravenous administration of saccharated ferric oxide. Over the course of treatment, she was diagnosed with tetany, which was attributed to hypocalcemia. Additional assessments of the patient revealed not only hypocalcemia, but also hypophosphatemia, hypomagnesemia, osteomalacia, and a high concentration of fibroblast growth factor 23 (314 pg/mL). Diagnoses: We diagnosed her with mineral imbalance-induced osteomalacia due to saccharated ferric oxide and short-bowel syndrome. Interventions: Magnesium replacement therapy and discontinuation of saccharated ferric oxide alone. Outcomes: These treatments were able to normalize her serum mineral levels and increase her bone mineral density. Lessons: This case suggests that adequate evaluation of serum minerals, including phosphate and magnesium, during saccharated ferric oxide administration may be necessary, especially in patients with short-bowel syndrome. PMID:28953654

  3. Fundamental Studies of Irradiation-Induced Defect Formation and Fission Product Dynamics in Oxide Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Stubbins, James

    2012-12-19

    The objective of this research program is to address major nuclear fuels performance issues for the design and use of oxide-type fuels in the current and advanced nuclear reactor applications. Fuel performance is a major issue for extending fuel burn-up which has the added advantage of reducing the used fuel waste stream. It will also be a significant issue with respect to developing advanced fuel cycle processes where it may be possible to incorporate minor actinides in various fuel forms so that they can be 'burned' rather than join the used fuel waste stream. The potential to fission or transmute minor actinides and certain long-lived fission product isotopes would transform the high level waste storage strategy by removing the need to consider fuel storage on the millennium time scale.

  4. High glucose-induced oxidative stress represses sirtuin deacetylase expression and increases histone acetylation leading to neural tube defects.

    Science.gov (United States)

    Yu, Jingwen; Wu, Yanqing; Yang, Peixin

    2016-05-01

    Aberrant epigenetic modifications are implicated in maternal diabetes-induced neural tube defects (NTDs). Because cellular stress plays a causal role in diabetic embryopathy, we investigated the possible role of the stress-resistant sirtuin (SIRT) family histone deacetylases. Among the seven sirtuins (SIRT1-7), pre-gestational maternal diabetes in vivo or high glucose in vitro significantly reduced the expression of SIRT 2 and SIRT6 in the embryo or neural stem cells, respectively. The down-regulation of SIRT2 and SIRT6 was reversed by superoxide dismutase 1 (SOD1) over-expression in the in vivo mouse model of diabetic embryopathy and the SOD mimetic, tempol and cell permeable SOD, PEGSOD in neural stem cell cultures. 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), a superoxide generating agent, mimicked high glucose-suppressed SIRT2 and SIRT6 expression. The acetylation of histone 3 at lysine residues 56 (H3K56), H3K14, H3K9, and H3K27, putative substrates of SIRT2 and SIRT6, was increased by maternal diabetes in vivo or high glucose in vitro, and these increases were blocked by SOD1 over-expression or tempol treatment. SIRT2 or SIRT6 over-expression abrogated high glucose-suppressed SIRT2 or SIRT6 expression, and prevented the increase in acetylation of their histone substrates. The potent sirtuin activator (SRT1720) blocked high glucose-increased histone acetylation and NTD formation, whereas the combination of a pharmacological SIRT2 inhibitor and a pan SIRT inhibitor mimicked the effect of high glucose on increased histone acetylation and NTD induction. Thus, diabetes in vivo or high glucose in vitro suppresses SIRT2 and SIRT6 expression through oxidative stress, and sirtuin down-regulation-induced histone acetylation may be involved in diabetes-induced NTDs. The mechanism underlying pre-gestational diabetes-induced neural tube defects (NTDs) is still elusive. Our study unravels a new epigenetic mechanism in which maternal diabetes-induced oxidative stress represses

  5. Fractional release of short-lived noble gases and iodine from HTGR fuel compact containing a fraction of coated fuel particles with through-coating defects

    International Nuclear Information System (INIS)

    Ogawa, Toru; Fukuda, Kosaku; Kobayashi, Fumiaki; Kikuchi, Teruo; Tobita, Tsutomu; Kashimura, Satoru; Kikuchi, Hironobu; Yamamoto, Katsumune.

    1986-10-01

    Fractional release (R/B) data of short-lived noble gases and iodine from sweep-gas irradiated HTGR fuel compacts were analyzed. Empirical formulas to predict R/B of 88 Kr as a function of temperature and fraction through-coating defects, and to calculate ratios of R/B's of other shortlived gases to that of 88 Kr were proposed. A method to predict R/B of iodine was also proposed. As for 131 I, a fission product of major safety concern, (R/B) I 131 ≅ (R/B) Xe 133 was predicted. Applying those methods, R/B from OGL-1 fuel element (5th and 6th) was predicted to show a good agreement with observation. (author)

  6. Accumulation of premutagenic DNA lesions in mice defective in removal of oxidative base damage

    Science.gov (United States)

    Klungland, Arne; Rosewell, Ian; Hollenbach, Stephan; Larsen, Elisabeth; Daly, Graham; Epe, Bernd; Seeberg, Erling; Lindahl, Tomas; Barnes, Deborah E.

    1999-01-01

    DNA damage generated by oxidant byproducts of cellular metabolism has been proposed as a key factor in cancer and aging. Oxygen free radicals cause predominantly base damage in DNA, and the most frequent mutagenic base lesion is 7,8-dihydro-8-oxoguanine (8-oxoG). This altered base can pair with A as well as C residues, leading to a greatly increased frequency of spontaneous G·C→T·A transversion mutations in repair-deficient bacterial and yeast cells. Eukaryotic cells use a specific DNA glycosylase, the product of the OGG1 gene, to excise 8-oxoG from DNA. To assess the role of the mammalian enzyme in repair of DNA damage and prevention of carcinogenesis, we have generated homozygous ogg1−/− null mice. These animals are viable but accumulate abnormal levels of 8-oxoG in their genomes. Despite this increase in potentially miscoding DNA lesions, OGG1-deficient mice exhibit only a moderately, but significantly, elevated spontaneous mutation rate in nonproliferative tissues, do not develop malignancies, and show no marked pathological changes. Extracts of ogg1 null mouse tissues cannot excise the damaged base, but there is significant slow removal in vivo from proliferating cells. These findings suggest that in the absence of the DNA glycosylase, and in apparent contrast to bacterial and yeast cells, an alternative repair pathway functions to minimize the effects of an increased load of 8-oxoG in the genome and maintain a low endogenous mutation frequency. PMID:10557315

  7. Thymidine kinase 2 deficiency-induced mtDNA depletion in mouse liver leads to defect β-oxidation.

    Directory of Open Access Journals (Sweden)

    Xiaoshan Zhou

    Full Text Available Thymidine kinase 2 (TK2 deficiency in humans causes mitochondrial DNA (mtDNA depletion syndrome. To study the molecular mechanisms underlying the disease and search for treatment options, we previously generated and described a TK2 deficient mouse strain (TK2(-/- that progressively loses its mtDNA. The TK2(-/- mouse model displays symptoms similar to humans harboring TK2 deficient infantile fatal encephalomyopathy. Here, we have studied the TK2(-/- mouse model to clarify the pathological role of progressive mtDNA depletion in liver for the severe outcome of TK2 deficiency. We observed that a gradual depletion of mtDNA in the liver of the TK2(-/- mice was accompanied by increasingly hypertrophic mitochondria and accumulation of fat vesicles in the liver cells. The levels of cholesterol and nonesterified fatty acids were elevated and there was accumulation of long chain acylcarnitines in plasma of the TK2(-/- mice. In mice with hepatic mtDNA levels below 20%, the blood sugar and the ketone levels dropped. These mice also exhibited reduced mitochondrial β-oxidation due to decreased transport of long chain acylcarnitines into the mitochondria. The gradual loss of mtDNA in the liver of the TK2(-/- mice causes impaired mitochondrial function that leads to defect β-oxidation and, as a result, insufficient production of ketone bodies and glucose. This study provides insight into the mechanism of encephalomyopathy caused by TK2 deficiency-induced mtDNA depletion that may be used to explore novel therapeutic strategies.

  8. Thymidine kinase 2 deficiency-induced mtDNA depletion in mouse liver leads to defect β-oxidation.

    Science.gov (United States)

    Zhou, Xiaoshan; Kannisto, Kristina; Curbo, Sophie; von Döbeln, Ulrika; Hultenby, Kjell; Isetun, Sindra; Gåfvels, Mats; Karlsson, Anna

    2013-01-01

    Thymidine kinase 2 (TK2) deficiency in humans causes mitochondrial DNA (mtDNA) depletion syndrome. To study the molecular mechanisms underlying the disease and search for treatment options, we previously generated and described a TK2 deficient mouse strain (TK2(-/-)) that progressively loses its mtDNA. The TK2(-/-) mouse model displays symptoms similar to humans harboring TK2 deficient infantile fatal encephalomyopathy. Here, we have studied the TK2(-/-) mouse model to clarify the pathological role of progressive mtDNA depletion in liver for the severe outcome of TK2 deficiency. We observed that a gradual depletion of mtDNA in the liver of the TK2(-/-) mice was accompanied by increasingly hypertrophic mitochondria and accumulation of fat vesicles in the liver cells. The levels of cholesterol and nonesterified fatty acids were elevated and there was accumulation of long chain acylcarnitines in plasma of the TK2(-/-) mice. In mice with hepatic mtDNA levels below 20%, the blood sugar and the ketone levels dropped. These mice also exhibited reduced mitochondrial β-oxidation due to decreased transport of long chain acylcarnitines into the mitochondria. The gradual loss of mtDNA in the liver of the TK2(-/-) mice causes impaired mitochondrial function that leads to defect β-oxidation and, as a result, insufficient production of ketone bodies and glucose. This study provides insight into the mechanism of encephalomyopathy caused by TK2 deficiency-induced mtDNA depletion that may be used to explore novel therapeutic strategies.

  9. Blast induces oxidative stress, inflammation, neuronal loss and subsequent short-term memory impairment in rats.

    Science.gov (United States)

    Cho, H J; Sajja, V S S S; Vandevord, P J; Lee, Y W

    2013-12-03

    Molecular and cellular mechanisms of brain injury after exposure to blast overpressure (BOP) are not clearly known. The present study hypothesizes that pro-oxidative and pro-inflammatory pathways in the brain may be responsible for neuronal loss and behavioral deficits following BOP exposure. Male Sprague-Dawley rats were anesthetized and exposed to calibrated BOP of 129.23±3.01kPa while controls received only anesthesia. In situ dihydroethidium fluorescence staining revealed that BOP significantly increased the production of reactive oxygen species in the brain. In addition, real-time reverse transcriptase-polymerase chain reaction, immunofluorescence staining and enzyme-linked immunosorbent assay demonstrated a significant up-regulation of mRNA and protein expressions of pro-inflammatory mediators, such as interferon-γ and monocyte chemoattractant protein-1, in brains collected from BOP-exposed animals compared with the controls. Furthermore, immunoreactivity of neuronal nuclei in brains indicated that fewer neurons were present following BOP exposure. Moreover, novel object recognition paradigm showed a significant impairment in the short-term memory at 2weeks following BOP exposure. These results suggest that pro-oxidative and pro-inflammatory environments in the brain could play a potential role in BOP-induced neuronal loss and behavioral deficits. It may provide a foundation for defining a molecular and cellular basis of the pathophysiology of blast-induced neurotrauma (BINT). It will also contribute to the development of new therapeutic approaches selectively targeting these pathways, which have great potential in the diagnosis and therapy of BINT. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  10. Probing of O2 vacancy defects and correlated magnetic, electrical and photoresponse properties in indium-tin oxide nanostructures by spectroscopic techniques

    Science.gov (United States)

    Ghosh, Shyamsundar; Dev, Bhupendra Nath

    2018-05-01

    Indium-tin oxide (ITO) 1D nanostructures with tunable morphologies i.e. nanorods, nanocombs and nanowires are grown on c-axis (0 0 0 1) sapphire (Al2O3) substrate in oxygen deficient atmosphere through pulsed laser deposition (PLD) technique and the effect of oxygen vacancies on optical, electrical, magnetic and photoresponse properties is investigated using spectroscopic methods. ITO nanostructures are found to be enriched with significant oxygen vacancy defects as evident from X-ray photoelectron and Raman spectroscopic analysis. Photoluminescence spectra exhibited intense mid-band blue emission at wavelength of region of 400-450 nm due to the electronic transition from conduction band maxima (CBM) to the singly ionized oxygen-vacancy (VO+) defect level within the band-gap. Interestingly, ITO nanostructures exhibited significant room-temperature ferromagnetism (RTFM) and the magnetic moment found proportional to concentration of VO+ defects which indicates VO+ defects are mainly responsible for the observed RTFM in nanostructures. ITO nanowires being enriched with more VO+ defects exhibited strongest RTFM as compared to other morphologies. Current voltage (I-V) characteristics of ITO nanostructures showed an enhancement of current under UV light as compared to dark which indicates such 1D nanostructure can be used as photovoltaic material. Hence, the study shows that there is ample opportunity to tailor the properties of ITOs through proper defect engineering's and such photosensitive ferromagnetic semiconductors might be promising for spintronic and photovoltaic applications.

  11. Transport physics and device modeling of zinc oxide thin-film transistors. Pt. II: Contact Resistance in Short Channel Devices

    NARCIS (Netherlands)

    Torricelli, F.; Meijboom, J.R.; Smits, E.; Tripathi, A.K.; Gelinck, G.H.; Colalongo, L.; Kovacs-Vajna, Z.M.; Leeuw, D. de; Cantatore, E.

    2011-01-01

    Abstract—Short-channel zinc oxide (ZnO) thin-film transistors (TFTs) are investigated in a wide range of temperatures and bias conditions. Scaling down the channel length, the TFT performance is seriously affected by contact resistances, which depend on gate voltage and temperature. To account for

  12. Transport physics and device modeling of zinc oxide thin film transistors - part II : contact resistance in short channel devices

    NARCIS (Netherlands)

    Torricelli, F.; Smits, E.C.P.; Meijboom, J.R.; Tripathi, A.K.; Gelinck, G.H.; Colalongo, L.; Kovacs-Vajna, Z.M.; Cantatore, E.

    2011-01-01

    Short-channel zinc oxide (ZnO) thin-film transistors (TFTs) are investigated in a wide range of temperatures and bias conditions. Scaling down the channel length, the TFT performance is seriously affected by contact resistances, which depend on gate voltage and temperature. To account for the

  13. Epididymis response partly compensates for spermatozoa oxidative defects in snGPx4 and GPx5 double mutant mice.

    Directory of Open Access Journals (Sweden)

    Anaïs Noblanc

    Full Text Available We report here that spermatozoa of mice lacking both the sperm nucleus glutathione peroxidase 4 (snGPx4 and the epididymal glutathione peroxidase 5 (GPx5 activities display sperm nucleus structural abnormalities including delayed and defective nuclear compaction, nuclear instability and DNA damage. We show that to counteract the GPx activity losses, the epididymis of the double KO animals mounted an antioxydant response resulting in a strong increase in the global H(2O(2-scavenger activity especially in the cauda epididymis. Quantitative RT-PCR data show that together with the up-regulation of epididymal scavengers (of the thioredoxin/peroxiredoxin system as well as glutathione-S-transferases the epididymis of double mutant animals increased the expression of several disulfide isomerases in an attempt to recover normal disulfide-bridging activity. Despite these compensatory mechanisms cauda-stored spermatozoa of double mutant animals show high levels of DNA oxidation, increased fragmentation and greater susceptibility to nuclear decondensation. Nevertheless, the enzymatic epididymal salvage response is sufficient to maintain full fertility of double KO males whatever their age, crossed with young WT female mice.

  14. Surface Oxidation of the High-Strength Steels Electrodeposited with Cu or Fe and the Resultant Defect Formation in Their Coating during the Following Galvanizing and Galvannealing Processes

    Science.gov (United States)

    Choi, Yun-Il; Beom, Won-Jin; Park, Chan-Jin; Paik, Doojin; Hong, Moon-Hi

    2010-12-01

    This study examined the surface oxidation of high-strength steels electrodeposited with Cu or Fe and the resultant defect formation in their coating during the following galvanizing and galvannealing processes. The high-strength steels were coated with an Cu or Fe layer by the electroplating method. Then, the coated steels were annealed in a reducing atmosphere, dipped in a molten zinc, and finally transformed into galvannealed steels through the galvannealing process. The formation of Si and Mn oxides on the surface of the high-strength steel was effectively suppressed, and the density of surface defects on the galvanized steel was significantly reduced by the pre-electrodeposition of Cu and Fe. This effect was more prominent for the steels electrodeposited at higher cathodic current densities. The finer electrodeposit layer formed at higher cathodic current density on the steels enabled the suppression of partial surface oxidation by Mn or Si and better wetting of Zn on the surface of the steels in the following galvanizing process. Furthermore, the pre-electrodeposited steels exhibited a smoother surface without surface cracks after the galvannealing process compared with the untreated steel. The diffusion of Fe and Zn in the Zn coating layer in the pre-electrodeposited steels appears to occur more uniformly during the galvannealing process due to the low density of surface defects induced by oxides.

  15. Non-classical polycrystalline silicon thin-film transistor with embedded block-oxide for suppressing the short channel effect

    International Nuclear Information System (INIS)

    Lin, Jyi-Tsong; Huang, Kuo-Dong; Hu, Shu-Fen

    2008-01-01

    In this paper, a polycrystalline silicon (polysilicon) thin-film transistor with a block oxide enclosing body, BTFT, is fabricated and investigated. By utilizing the block-oxide structure of thin-film transistors, the BTFT is shown to suppress the short channel effect. This proposed structure is formed by burying self-aligned oxide spacers along the sidewalls of the source and drain junctions, which reduces the P–N junction area, thereby reducing the junction capacitance and leakage current. Measurements demonstrate that the BTFT eliminates the punch-through effect even down to gate lengths of 1.5 µm, whereas the conventional TFT suffers serious short channel effects at this gate length

  16. Short-Term Synaptic Plasticity Regulation in Solution-Gated Indium-Gallium-Zinc-Oxide Electric-Double-Layer Transistors.

    Science.gov (United States)

    Wan, Chang Jin; Liu, Yang Hui; Zhu, Li Qiang; Feng, Ping; Shi, Yi; Wan, Qing

    2016-04-20

    In the biological nervous system, synaptic plasticity regulation is based on the modulation of ionic fluxes, and such regulation was regarded as the fundamental mechanism underlying memory and learning. Inspired by such biological strategies, indium-gallium-zinc-oxide (IGZO) electric-double-layer (EDL) transistors gated by aqueous solutions were proposed for synaptic behavior emulations. Short-term synaptic plasticity, such as paired-pulse facilitation, high-pass filtering, and orientation tuning, was experimentally emulated in these EDL transistors. Most importantly, we found that such short-term synaptic plasticity can be effectively regulated by alcohol (ethyl alcohol) and salt (potassium chloride) additives. Our results suggest that solution gated oxide-based EDL transistors could act as the platforms for short-term synaptic plasticity emulation.

  17. Incipient microphase separation in short chain perfluoropolyether-block-poly(ethylene oxide) copolymers.

    Science.gov (United States)

    Chintapalli, Mahati; Timachova, Ksenia; Olson, Kevin R; Banaszak, Michał; Thelen, Jacob L; Mecham, Sue J; DeSimone, Joseph M; Balsara, Nitash P

    2017-06-07

    Incipient microphase separation is observed by wide angle X-ray scattering (WAXS) in short chain multiblock copolymers consisting of perfluoropolyether (PFPE) and poly(ethylene oxide) (PEO) segments. Two PFPE-PEO block copolymers were studied; one with dihydroxyl end groups and one with dimethyl carbonate end groups. Despite having a low degree of polymerization (N ∼ 10), these materials exhibited significant scattering intensity, due to disordered concentration fluctuations between their PFPE-rich and PEO-rich domains. The disordered scattering intensity was fit to a model based on a multicomponent random phase approximation to determine the value of the interaction parameter, χ, and the radius of gyration, R g . Over the temperature range 30-90 °C, the values of χ were determined to be very large (∼2-2.5), indicating a high degree of immiscibility between the PFPE and PEO blocks. In PFPE-PEO, due to the large electron density contrast between the fluorinated and non-fluorinated block and the high value of χ, disordered scattering was detected at intermediate scattering angles, (q ∼ 2 nm -1 ) for relatively small polymer chains. Our ability to detect concentration fluctuations was enabled by both a relatively large value of χ and significant scattering contrast.

  18. Nitric oxide affects short-term olfactory memory in the antennal lobe of Manduca sexta.

    Science.gov (United States)

    Gage, Stephanie L; Daly, Kevin C; Nighorn, Alan

    2013-09-01

    Nitric oxide (NO) is thought to play an important neuromodulatory role in olfaction. We are using the hawkmoth Manduca sexta to investigate the function of NO signaling in the antennal lobe (AL; the primary olfactory network in invertebrates). We have found previously that NO is present at baseline levels, dramatically increases in response to odor stimulation, and alters the electrophysiology of AL neurons. It is unclear, however, how these effects contribute to common features of olfactory systems such as olfactory learning and memory, odor detection and odor discrimination. In this study, we used chemical detection and a behavioral approach to further examine the function of NO in the AL. We found that basal levels of NO fluctuate with the daily light cycle, being higher during the nocturnal active period. NO also appears to be necessary for short-term olfactory memory. NO does not appear to affect odor detection, odor discrimination between dissimilar odorants, or learning acquisition. These findings suggest a modulatory role for NO in the timing of olfactory-guided behaviors.

  19. Importance of doping, dopant distribution, and defects on electronic band structure alteration of metal oxide nanoparticles: Implications for reactive oxygen species

    International Nuclear Information System (INIS)

    Saleh, Navid B.; Milliron, Delia J.; Aich, Nirupam; Katz, Lynn E.; Liljestrand, Howard M.; Kirisits, Mary Jo

    2016-01-01

    Metal oxide nanoparticles (MONPs) are considered to have the potency to generate reactive oxygen species (ROS), one of the key mechanisms underlying nanotoxicity. However, the nanotoxicology literature demonstrates a lack of consensus on the dominant toxicity mechanism(s) for a particular MONP. Moreover, recent literature has studied the correlation between band structure of pristine MONPs to their ability to introduce ROS and thus has downplayed the ROS-mediated toxicological relevance of a number of such materials. On the other hand, material science can control the band structure of these materials to engineer their electronic and optical properties and thereby is constantly modulating the pristine electronic structure. Since band structure is the fundamental material property that controls ROS-producing ability, band tuning via introduction of dopants and defects needs careful consideration in toxicity assessments. This commentary critically evaluates the existing material science and nanotoxicity literature and identifies the gap in our understanding of the role of important crystal structure features (i.e., dopants and defects) on MONPs' electronic structure alteration as well as their ROS-generation capability. Furthermore, this commentary provides suggestions on characterization techniques to evaluate dopants and defects on the crystal structure and identifies research needs for advanced theoretical predictions of their electronic band structures and ROS-generation abilities. Correlation of electronic band structure and ROS will not only aid in better mechanistic assessment of nanotoxicity but will be impactful in designing and developing ROS-based applications ranging from water disinfection to next-generation antibiotics and even cancer therapeutics. - Highlights: • Metal oxide nanoparticles (MONPs) produce reactive oxygen species (ROS) • Band structure of pristine MONPs is different than those with dopants/defects • Dopants/defects modulate

  20. Importance of doping, dopant distribution, and defects on electronic band structure alteration of metal oxide nanoparticles: Implications for reactive oxygen species

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, Navid B., E-mail: navid.saleh@utexas.edu [Department of Civil, Architectural, and Environmental Engineering, University of Texas, Austin, TX 78712 (United States); Milliron, Delia J. [McKetta Department of Chemical Engineering, University of Texas, Austin, TX 78712 (United States); Aich, Nirupam [Department of Civil, Structural and Environmental Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260 (United States); Katz, Lynn E.; Liljestrand, Howard M.; Kirisits, Mary Jo [Department of Civil, Architectural, and Environmental Engineering, University of Texas, Austin, TX 78712 (United States)

    2016-10-15

    Metal oxide nanoparticles (MONPs) are considered to have the potency to generate reactive oxygen species (ROS), one of the key mechanisms underlying nanotoxicity. However, the nanotoxicology literature demonstrates a lack of consensus on the dominant toxicity mechanism(s) for a particular MONP. Moreover, recent literature has studied the correlation between band structure of pristine MONPs to their ability to introduce ROS and thus has downplayed the ROS-mediated toxicological relevance of a number of such materials. On the other hand, material science can control the band structure of these materials to engineer their electronic and optical properties and thereby is constantly modulating the pristine electronic structure. Since band structure is the fundamental material property that controls ROS-producing ability, band tuning via introduction of dopants and defects needs careful consideration in toxicity assessments. This commentary critically evaluates the existing material science and nanotoxicity literature and identifies the gap in our understanding of the role of important crystal structure features (i.e., dopants and defects) on MONPs' electronic structure alteration as well as their ROS-generation capability. Furthermore, this commentary provides suggestions on characterization techniques to evaluate dopants and defects on the crystal structure and identifies research needs for advanced theoretical predictions of their electronic band structures and ROS-generation abilities. Correlation of electronic band structure and ROS will not only aid in better mechanistic assessment of nanotoxicity but will be impactful in designing and developing ROS-based applications ranging from water disinfection to next-generation antibiotics and even cancer therapeutics. - Highlights: • Metal oxide nanoparticles (MONPs) produce reactive oxygen species (ROS) • Band structure of pristine MONPs is different than those with dopants/defects • Dopants/defects modulate

  1. Synthesis, structuring and characterization of rare earth oxide thin films: Modeling of the effects of stress and defects on the phase stability

    International Nuclear Information System (INIS)

    Gaboriaud, R.J.; Paumier, F.; Lacroix, B.

    2014-01-01

    This work studies the effects of the deposition parameters on the microstructure and the related residual stress in a rare earth oxide thin film. This study is focused on the yttrium sesquioxide (Y 2 O 3 ) thin films deposited on Si (100) substrates using the ion beam sputtering technique. This technique allows the control of the microstructure and the related residual stress in the thin films by monitoring the energy of the argon beam used in the deposition process. Measurements of the stresses within the oxide layer were performed by the X-ray diffraction-sin 2 Ψ method. The results show that the classic model of a pure biaxial in-plane model of stress, generally proposed in thin films, is not satisfying. A model that includes a hydrostatic stress due to the crystalline defects generated during the deposition process and a biaxial stress called a fixation stress, gives a good agreement with the experimental results. This modeling of the residual stress, based on nanometer-scale inclusions (point, extended defects) inducing a hydrostatic stress field, leads to a quantitative analysis of the nature and the concentration of the defects. This work shows results that establish a relationship between residual stress, defects and non-equilibrium phase stabilization during growth. - Highlights: • Microstructure of Y 2 O 3 thin films • Measurements of residual stresses in the thin films • Modeling of a triaxial residual stress state • Stress-induced stabilization of non-equilibrium phase

  2. Short-term effects of electronic and tobacco cigarettes on exhaled nitric oxide

    International Nuclear Information System (INIS)

    Marini, Sara; Buonanno, Giorgio; Stabile, Luca; Ficco, Giorgio

    2014-01-01

    The objective of this study was to compare the short-term respiratory effects due to the inhalation of electronic and conventional tobacco cigarette-generated mainstream aerosols through the measurement of the exhaled nitric oxide (eNO). To this purpose, twenty-five smokers were asked to smoke a conventional cigarette and to vape an electronic cigarette (with and without nicotine), and an electronic cigarette without liquid (control session). Electronic and tobacco cigarette mainstream aerosols were characterized in terms of total particle number concentrations and size distributions. On the basis of the measured total particle number concentrations and size distributions, the average particle doses deposited in alveolar and tracheobronchial regions of the lungs for a single 2-s puff were also estimated considering a subject performing resting (sitting) activity. Total particle number concentrations in the mainstream resulted equal to 3.5 ± 0.4 × 10 9 , 5.1 ± 0.1 × 10 9 , and 3.1 ± 0.6 × 10 9 part. cm −3 for electronic cigarettes without nicotine, with nicotine, and for conventional cigarettes, respectively. The corresponding alveolar doses for a resting subject were estimated equal to 3.8 × 10 10 , 5.2 × 10 10 and 2.3 × 10 10 particles. The mean eNO variations measured after each smoking/vaping session were equal to 3.2 ppb, 2.7 ppb and 2.8 ppb for electronic cigarettes without nicotine, with nicotine, and for conventional cigarettes, respectively; whereas, negligible eNO changes were measured in the control session. Statistical tests performed on eNO data showed statistically significant differences between smoking/vaping sessions and the control session, thus confirming a similar effect on human airways whatever the cigarette smoked/vaped, the nicotine content, and the particle dose received. - Highlights: • Electronic cigarettes (with and without nicotine) mainstream aerosols were analyzed; • Particle number concentrations and size distributions

  3. Short-term effects of electronic and tobacco cigarettes on exhaled nitric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Marini, Sara, E-mail: s.marini@unicas.it [Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino (Italy); Buonanno, Giorgio [Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino (Italy); Queensland University of Technology, Brisbane (Australia); Stabile, Luca; Ficco, Giorgio [Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino (Italy)

    2014-07-01

    The objective of this study was to compare the short-term respiratory effects due to the inhalation of electronic and conventional tobacco cigarette-generated mainstream aerosols through the measurement of the exhaled nitric oxide (eNO). To this purpose, twenty-five smokers were asked to smoke a conventional cigarette and to vape an electronic cigarette (with and without nicotine), and an electronic cigarette without liquid (control session). Electronic and tobacco cigarette mainstream aerosols were characterized in terms of total particle number concentrations and size distributions. On the basis of the measured total particle number concentrations and size distributions, the average particle doses deposited in alveolar and tracheobronchial regions of the lungs for a single 2-s puff were also estimated considering a subject performing resting (sitting) activity. Total particle number concentrations in the mainstream resulted equal to 3.5 ± 0.4 × 10{sup 9}, 5.1 ± 0.1 × 10{sup 9}, and 3.1 ± 0.6 × 10{sup 9} part. cm{sup −3} for electronic cigarettes without nicotine, with nicotine, and for conventional cigarettes, respectively. The corresponding alveolar doses for a resting subject were estimated equal to 3.8 × 10{sup 10}, 5.2 × 10{sup 10} and 2.3 × 10{sup 10} particles. The mean eNO variations measured after each smoking/vaping session were equal to 3.2 ppb, 2.7 ppb and 2.8 ppb for electronic cigarettes without nicotine, with nicotine, and for conventional cigarettes, respectively; whereas, negligible eNO changes were measured in the control session. Statistical tests performed on eNO data showed statistically significant differences between smoking/vaping sessions and the control session, thus confirming a similar effect on human airways whatever the cigarette smoked/vaped, the nicotine content, and the particle dose received. - Highlights: • Electronic cigarettes (with and without nicotine) mainstream aerosols were analyzed; • Particle number

  4. Evaluation of crystallographic strain, rotation and defects in functional oxides by the moiré effect in scanning transmission electron microscopy

    Science.gov (United States)

    Naden, A. B.; O'Shea, K. J.; MacLaren, D. A.

    2018-04-01

    Moiré patterns in scanning transmission electron microscopy (STEM) images of epitaxial perovskite oxides are used to assess strain and defect densities over fields of view extending over several hundred nanometers. The patterns arise from the geometric overlap of the rastered STEM electron beam and the samples’ crystal periodicities and we explore the emergence and application of these moiré fringes for rapid strain analysis. Using the epitaxial functional oxide perovskites BiFeO3 and Pr1-x Ca x MnO3, we discuss the impact of large degrees of strain on the quantification of STEM moiré patterns, identify defects in the fringe patterns and quantify strain and lattice rotation. Such a wide-area analysis of crystallographic strain and defects is crucial for developing structure-function relations of functional oxides and we find the STEM moiré technique to be an attractive means of structural assessment that can be readily applied to low dose studies of damage sensitive crystalline materials.

  5. Implications of electronic short circuiting in plasma sprayed solid oxide fuel cells on electrode performance evaluation by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    White, B.D. [Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Sciences Lane, Vancouver, British Columbia (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, Ontario (Canada)

    2008-02-15

    Electronic short circuiting of the electrolyte in a solid oxide fuel cell (SOFC) arising from flaws in the plasma spray fabrication process has been found to have a significant effect on the perceived performance of the electrodes, as evaluated by electrochemical impedance spectroscopy (EIS). The presence of a short circuit has been found to lead to the underestimation of the electrode polarization resistance (R{sub p}) and hence an overestimation of electrode performance. The effect is particularly noticeable when electrolyte resistance is relatively high, for example during low to intermediate temperature operation, leading to an obvious deviation from the expected Arrhenius-type temperature dependence of R{sub p}. A method is developed for determining the real electrode performance from measurements of various cell properties, and strategies for eliminating the occurrence of short circuiting in plasma sprayed cells are identified. (author)

  6. Implications of electronic short circuiting in plasma sprayed solid oxide fuel cells on electrode performance evaluation by electrochemical impedance spectroscopy

    Science.gov (United States)

    White, B. D.; Kesler, O.

    Electronic short circuiting of the electrolyte in a solid oxide fuel cell (SOFC) arising from flaws in the plasma spray fabrication process has been found to have a significant effect on the perceived performance of the electrodes, as evaluated by electrochemical impedance spectroscopy (EIS). The presence of a short circuit has been found to lead to the underestimation of the electrode polarization resistance (R p) and hence an overestimation of electrode performance. The effect is particularly noticeable when electrolyte resistance is relatively high, for example during low to intermediate temperature operation, leading to an obvious deviation from the expected Arrhenius-type temperature dependence of R p. A method is developed for determining the real electrode performance from measurements of various cell properties, and strategies for eliminating the occurrence of short circuiting in plasma sprayed cells are identified.

  7. Short and long term biosorption of silica-coated iron oxide nanoparticles in heterotrophic biofilms

    International Nuclear Information System (INIS)

    Herrling, Maria P.; Lackner, Susanne; Tatti, Oleg; Guthausen, Gisela; Delay, Markus; Franzreb, Matthias; Horn, Harald

    2016-01-01

    The increased application of engineered nanoparticles (ENP) in industrial processes and consumer products has raised concerns about their impact on health and environmental safety. When ENP enter the global water cycle by e.g. wastewater streams, wastewater treatment plants (WWTP) represent potential sinks for ENP. During biological WWT, the attachment of ENP to biofilms is responsible for the desired removal of ENP from the water phase avoiding their release into the aquatic environment. However, the fundamental mechanisms guiding the interactions between ENP and biofilms are not yet fully understood. Therefore, this study investigates the behavior and biosorption of inorganic ENP, here magnetic iron oxide nanoparticles coated with silica (scFe_3O_4-NP), with heterotrophic biofilms at different time scales. Their magnetic properties enable to follow scFe_3O_4-NP in the biofilm system by a magnetic susceptibility balance and magnetic resonance imaging. Biofilms were exposed to scFe_3O_4-NP at short contact times (5 min) in flow cells and complementary, scFe_3O_4-NP were introduced into a moving bed biofilm reactor (MBBR) to be observed for 27 d. Mass balances revealed that scFe_3O_4-NP sorbed to the biofilm within a few minutes, but that the total biosorption was rather low (3.2 μg Fe/mg TSS). scFe_3O_4-NP mainly sorbed to the biofilm surface inducing the detachment of outer biofilm parts starting after an exposure time of 3 h in the MBBR. The biosorption depended on the exposure concentration of scFe_3O_4-NP, but less on the contact time. Most scFe_3O_4-NP exited the flow cell (up to 65%) and the MBBR (57%) via the effluent. This effect was favored by the stabilization of scFe_3O_4-NP in the bulk liquid by organic matter leading to a low retention capacity of the MBBR system. The results contribute to improve our understanding about the fate of ENP in environmental and in technical biofilm systems and give indications for future investigations needed

  8. The role of healed N-vacancy defective BC2N sheet and nanotube by NO molecule in oxidation of NO and CO gas molecules

    Science.gov (United States)

    Nematollahi, Parisa; Esrafili, Mehdi D.; Neyts, Erik C.

    2018-06-01

    In this study, the healing of N-vacancy boron carbonitride nanosheet (NV-BC2NNS) and nanotube (NV-BC2NNT) by NO molecule is studied by means of density functional theory calculations. Two different N-vacancies are considered in each of these structures in which the vacancy site is surrounded by either three B-atoms (NB) or by two B- and one C-atom (NBC). By means of the healed BC2NNS and BC2NNT as a support, the removal of two toxic gas molecules (NO and CO) are applicable. It should be noted that the obtained energy barriers of both healing and oxidizing processes are significantly lower than those of graphene, carbon nanotubes or boron nitride nanostructures. Also, at the end of the oxidation process, the pure BC2NNS or BC2NNT is obtained without any additional defects. Therefore, by using this method, we can considerably purify the defective BC2NNS/BC2NNT. Moreover, according to the thermochemistry calculations we can further confirm that the healing process of the NV-BC2NNS and NV-BC2NNT by NO are feasible at room temperature. So, we can claim that this study could be very helpful in both purifying the defective BC2NNS/BC2NNT while in the same effort removing toxic NO and CO gases.

  9. Defect Characterization of Pyroelectric Materials

    National Research Council Canada - National Science Library

    Keeble, David

    2002-01-01

    Two methods for identify point defects applicable to the study of technologically relevant pyroelectric oxide materials have been investigated, namely Positron Annihilation Lifetime Spectroscopy (PALS...

  10. Short-term and long-term effects of transient exogenous cortisol manipulation on oxidative stress in juvenile brown trout.

    Science.gov (United States)

    Birnie-Gauvin, Kim; Peiman, Kathryn S; Larsen, Martin H; Aarestrup, Kim; Willmore, William G; Cooke, Steven J

    2017-05-01

    In the wild, animals are exposed to a growing number of stressors with increasing frequency and intensity, as a result of human activities and human-induced environmental change. To fully understand how wild organisms are affected by stressors, it is crucial to understand the physiology that underlies an organism's response to a stressor. Prolonged levels of elevated glucocorticoids are associated with a state of chronic stress and decreased fitness. Exogenous glucocorticoid manipulation reduces an individual's ability to forage, avoid predators and grow, thereby limiting the resources available for physiological functions like defence against oxidative stress. Using brown trout ( Salmo trutta ), we evaluated the short-term (2 weeks) and long-term (4 months over winter) effects of exogenous cortisol manipulations (versus relevant shams and controls) on the oxidative status of wild juveniles. Cortisol caused an increase in glutathione over a 2 week period and appeared to reduce glutathione over winter. Cortisol treatment did not affect oxidative stress levels or low molecular weight antioxidants. Cortisol caused a significant decrease in growth rates but did not affect predation risk. Over-winter survival in the stream was associated with low levels of oxidative stress and glutathione. Thus, oxidative stress may be a mechanism by which elevated cortisol causes negative physiological effects. © 2017. Published by The Company of Biologists Ltd.

  11. Acidithiobacillus caldus sulfur oxidation model based on transcriptome analysis between the wild type and sulfur oxygenase reductase defective mutant.

    Directory of Open Access Journals (Sweden)

    Linxu Chen

    Full Text Available Acidithiobacillus caldus (A. caldus is widely used in bio-leaching. It gains energy and electrons from oxidation of elemental sulfur and reduced inorganic sulfur compounds (RISCs for carbon dioxide fixation and growth. Genomic analyses suggest that its sulfur oxidation system involves a truncated sulfur oxidation (Sox system (omitting SoxCD, non-Sox sulfur oxidation system similar to the sulfur oxidation in A. ferrooxidans, and sulfur oxygenase reductase (SOR. The complexity of the sulfur oxidation system of A. caldus generates a big obstacle on the research of its sulfur oxidation mechanism. However, the development of genetic manipulation method for A. caldus in recent years provides powerful tools for constructing genetic mutants to study the sulfur oxidation system.An A. caldus mutant lacking the sulfur oxygenase reductase gene (sor was created and its growth abilities were measured in media using elemental sulfur (S(0 and tetrathionate (K(2S(4O(6 as the substrates, respectively. Then, comparative transcriptome analysis (microarrays and real-time quantitative PCR of the wild type and the Δsor mutant in S(0 and K(2S(4O(6 media were employed to detect the differentially expressed genes involved in sulfur oxidation. SOR was concluded to oxidize the cytoplasmic elemental sulfur, but could not couple the sulfur oxidation with the electron transfer chain or substrate-level phosphorylation. Other elemental sulfur oxidation pathways including sulfur diooxygenase (SDO and heterodisulfide reductase (HDR, the truncated Sox pathway, and the S(4I pathway for hydrolysis of tetrathionate and oxidation of thiosulfate in A. caldus are proposed according to expression patterns of sulfur oxidation genes and growth abilities of the wild type and the mutant in different substrates media.An integrated sulfur oxidation model with various sulfur oxidation pathways of A. caldus is proposed and the features of this model are summarized.

  12. Defects in tor regulatory complexes retard aging and carbonyl/oxidative stress development in yeast Sассharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    B. V. Homza

    2014-02-01

    Full Text Available TOR signaling pathway first described in yeast S. сerevisiae is the highly conserved regulator of eukaryotic cell growth, aging and stress resistance. The effect of nitrogen sources, in particular amino acids, on the activity of TOR signaling pathway is well studied, however its relation to carbohydrates is poor understood. The aim of the present study is expanding of our understanding of potential role of TOR regulatory complexes in development of carbonyl/oxidative stress that can result from yeast cultivation on glucose and fructose. It has been shown that the level of α-dicarbonyl compounds and protein carbonyl groups increased with time of yeast cultivation and was higher in cells grown on fructose that demonstrated their accelerated aging and carbonyl/oxidative stress development as compared with cells grown on glucose. The strains defective in TOR proteins cultivated in the presence of glucose as well as fructose demonstrated lower markers of the stress and aging than parental strain. Thus these data confirmed the previous conclusion on fructose more potent ability to cause carbonyl/oxidative stress and accelerated aging in S. cerevisiae as compared with glucose. However, defects in TOR regulatory complexes retard aging and development of the stress in yeast independent on the type of carbohydrate in the cultivation medium.

  13. The effect of defects on the catalytic activity of single Au atom supported carbon nanotubes and reaction mechanism for CO oxidation.

    Science.gov (United States)

    Ali, Sajjad; Fu Liu, Tian; Lian, Zan; Li, Bo; Sheng Su, Dang

    2017-08-23

    The mechanism of CO oxidation by O 2 on a single Au atom supported on pristine, mono atom vacancy (m), di atom vacancy (di) and the Stone Wales defect (SW) on single walled carbon nanotube (SWCNT) surface is systematically investigated theoretically using density functional theory. We determine that single Au atoms can be trapped effectively by the defects on SWCNTs. The defects on SWCNTs can enhance both the binding strength and catalytic activity of the supported single Au atom. Fundamental aspects such as adsorption energy and charge transfer are elucidated to analyze the adsorption properties of CO and O 2 and co-adsorption of CO and O 2 molecules. It is found that CO binds stronger than O 2 on Au supported SWCNT. We clearly demonstrate that the defected SWCNT surface promotes electron transfer from the supported single Au atom to O 2 molecules. On the other hand, this effect is weaker for pristine SWCNTs. It is observed that the high density of spin-polarized states are localized in the region of the Fermi level due to the strong interactions between Au (5d orbital) and the adjacent carbon (2p orbital) atoms, which influence the catalytic performance. In addition, we elucidate both the Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms of CO oxidation by O 2 . For the LH pathway, the barriers of the rate-limiting step are calculated to be 0.02 eV and 0.05 eV for Au/m-SWCNT and Au/di-SWCNT, respectively. To regenerate the active sites, an ER-like reaction occurs to form a second CO 2 molecule. The ER pathway is observed on Au/m-SWCNT, Au/SW-SWCNT and Au/SWCNT in which the Au/m-SWCNT has a smaller barrier. The comparison with a previous study (Lu et al., J. Phys. Chem. C, 2009, 113, 20156-20160.) indicates that the curvature effect of SWCNTs is important for the catalytic property of the supported single Au. Overall, Au/m-SWCNT is identified as the most active catalyst for CO oxidation compared to pristine SWCNT, SW-SWCNT and di-SWCNT. Our findings give a

  14. Mitochondrial oxidative stress contributes differently to rat pancreatic islet cell apoptosis and insulin secretory defects after prolonged culture in a low non-stimulating glucose concentration.

    Science.gov (United States)

    Roma, L P; Pascal, S M; Duprez, J; Jonas, J-C

    2012-08-01

    Pancreatic beta cells chronically exposed to low glucose concentrations show signs of oxidative stress, loss of glucose-stimulated insulin secretion (GSIS) and increased apoptosis. Our aim was to confirm the role of mitochondrial oxidative stress in rat islet cell apoptosis under these culture conditions and to evaluate whether its reduction similarly improves survival and GSIS. Apoptosis, oxidative stress-response gene mRNA expression and glucose-induced stimulation of mitochondrial metabolism, intracellular Ca(2+) concentration and insulin secretion were measured in male Wistar rat islets cultured for 1 week in RPMI medium containing 5-10 mmol/l glucose with or without manganese(III)tetrakis(4-benzoic acid)porphyrin (MnTBAP) or N-acetyl-L-: cysteine (NAC). Oxidative stress was measured in islet cell clusters cultured under similar conditions using cytosolic and mitochondrial redox-sensitive green fluorescent protein (roGFP1/mt-roGFP1). Prolonged culture in 5 vs 10 mmol/l glucose increased mt-roGFP1 (but not roGFP1) oxidation followed by beta cell apoptosis and loss of GSIS resulting from reduced insulin content, mitochondrial metabolism, Ca(2+) influx and Ca(2+)-induced secretion. Tolbutamide-induced, but not high K(+)-induced, Ca(2+) influx was also suppressed. Under these conditions, MnTBAP, but not NAC, triggered parallel ~50-70% reductions in mt-roGFP1 oxidation and beta cell apoptosis, but failed to protect against the loss of GSIS despite significant improvement in glucose-induced and tolbutamide-induced Ca(2+) influx. Mitochondrial oxidative stress contributes differently to rat pancreatic islet cell apoptosis and insulin secretory defects during culture in a low glucose concentration. Thus, targeting beta cell survival may not be sufficient to restore insulin secretion when beta cells suffer from prolonged mitochondrial oxidative stress, e.g. in the context of reduced glucose metabolism.

  15. Short and long term biosorption of silica-coated iron oxide nanoparticles in heterotrophic biofilms

    Energy Technology Data Exchange (ETDEWEB)

    Herrling, Maria P. [Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany); Lackner, Susanne [Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany); Urban Bioengineering for Resource Recovery, Bauhaus-Institute for Infrastructure Solutions, Bauhaus-Universität Weimar, Coudraystraße 7, 99423 Weimar (Germany); Tatti, Oleg [Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany); Guthausen, Gisela [Pro" 2NMR, Institute for Biological Interfaces 4 and Institute for Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, Adenauerring 20b, 76131 Karlsruhe (Germany); Delay, Markus [Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany); Franzreb, Matthias [Institute of Functional Interfaces, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Horn, Harald, E-mail: harald.horn@kit.edu [Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany); DVGW Research Laboratories for Water Chemistry and Water Technology, Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany)

    2016-02-15

    The increased application of engineered nanoparticles (ENP) in industrial processes and consumer products has raised concerns about their impact on health and environmental safety. When ENP enter the global water cycle by e.g. wastewater streams, wastewater treatment plants (WWTP) represent potential sinks for ENP. During biological WWT, the attachment of ENP to biofilms is responsible for the desired removal of ENP from the water phase avoiding their release into the aquatic environment. However, the fundamental mechanisms guiding the interactions between ENP and biofilms are not yet fully understood. Therefore, this study investigates the behavior and biosorption of inorganic ENP, here magnetic iron oxide nanoparticles coated with silica (scFe{sub 3}O{sub 4}-NP), with heterotrophic biofilms at different time scales. Their magnetic properties enable to follow scFe{sub 3}O{sub 4}-NP in the biofilm system by a magnetic susceptibility balance and magnetic resonance imaging. Biofilms were exposed to scFe{sub 3}O{sub 4}-NP at short contact times (5 min) in flow cells and complementary, scFe{sub 3}O{sub 4}-NP were introduced into a moving bed biofilm reactor (MBBR) to be observed for 27 d. Mass balances revealed that scFe{sub 3}O{sub 4}-NP sorbed to the biofilm within a few minutes, but that the total biosorption was rather low (3.2 μg Fe/mg TSS). scFe{sub 3}O{sub 4}-NP mainly sorbed to the biofilm surface inducing the detachment of outer biofilm parts starting after an exposure time of 3 h in the MBBR. The biosorption depended on the exposure concentration of scFe{sub 3}O{sub 4}-NP, but less on the contact time. Most scFe{sub 3}O{sub 4}-NP exited the flow cell (up to 65%) and the MBBR (57%) via the effluent. This effect was favored by the stabilization of scFe{sub 3}O{sub 4}-NP in the bulk liquid by organic matter leading to a low retention capacity of the MBBR system. The results contribute to improve our understanding about the fate of ENP in environmental and in

  16. Defects in semiconductors

    CERN Document Server

    Romano, Lucia; Jagadish, Chennupati

    2015-01-01

    This volume, number 91 in the Semiconductor and Semimetals series, focuses on defects in semiconductors. Defects in semiconductors help to explain several phenomena, from diffusion to getter, and to draw theories on materials' behavior in response to electrical or mechanical fields. The volume includes chapters focusing specifically on electron and proton irradiation of silicon, point defects in zinc oxide and gallium nitride, ion implantation defects and shallow junctions in silicon and germanium, and much more. It will help support students and scientists in their experimental and theoret

  17. Short review of high-pressure crystal growth and magnetic and electrical properties of solid-state osmium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Yamaura, Kazunari, E-mail: YAMAURA.Kazunari@nims.go.jp [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 10 West 8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan)

    2016-04-15

    High-pressure crystal growth and synthesis of selected solid-state osmium oxides, many of which are perovskite-related types, are briefly reviewed, and their magnetic and electrical properties are introduced. Crystals of the osmium oxides, including NaOsO{sub 3}, LiOsO{sub 3}, and Na{sub 2}OsO{sub 4}, were successfully grown under high-pressure and high-temperature conditions at 6 GPa in the presence of an appropriate amount of flux in a belt-type apparatus. The unexpected discovery of a magnetic metal–insulator transition in NaOsO{sub 3}, a ferroelectric-like transition in LiOsO{sub 3}, and high-temperature ferrimagnetism driven by a local structural distortion in Ca{sub 2}FeOsO{sub 6} may represent unique features of the osmium oxides. The high-pressure and high-temperature synthesis and crystal growth has played a central role in the development of solid-state osmium oxides and the elucidation of their magnetic and electronic properties toward possible use in multifunctional devices. - Graphical Abstract: Flux-grown crystals of NaOsO{sub 3} under high-pressure and high-temperature conditions in a belt-type apparatus. The crystal shows a magnetically driven metal–insulator transition at a temperature of 410 K. - Highlights: • Short review of high-pressure crystal growth of solid-state osmium oxides. • Wide variety of magnetic properties of solid-state osmium oxides. • Perovskite and related dense structures stabilized at 3–17 GPa.

  18. SrFe1‑xMoxO2+δ : parasitic ferromagnetism in an infinite-layer iron oxide with defect structures induced by interlayer oxygen

    Science.gov (United States)

    Guo, Jianhui; Shi, Lei; Zhao, Jiyin; Wang, Yang; Yuan, Xueyou; Li, Yang; Wu, Liang

    2018-04-01

    The recent discovered compound SrFeO2 is an infinite-layer-structure iron oxide with unusual square-planar coordination of Fe2+ ions. In this study, SrFe1‑xMoxO2+δ (x parasitic ferromagnetism of the compound and its relationship to the defect structures are investigated. It is found that substitution of high-valent Mo6+ for Fe2+ results in excess oxygen anions O2‑ inserted at the interlayer sites for charge compensation, which further causes large atomic displacements along the c-axis. Due to the robust but flexible Fe-O-Fe framework, the samples are well crystallized within the ab-plane, but are significantly poorer crystallized along the c-axis. Defect structures including local lattice distortions and edge dislocations responsible for the lowered crystallinity are observed by high resolution transmission electron microscopy. Both the magnetic measurements and electron spin resonance spectra provide the evidence of a parasitic ferromagnetism (FM). The week FM interaction originated from the imperfect antiferromagnetic (AFM) ordering could be ascribed to the introduction of uncompensated magnetic moments due to substitution of Mo6+ (S = 0) for Fe2+ (S = 2) and the canted/frustrated spins resulted from defect structures.

  19. Melatonin protects against maternal obesity-associated oxidative stress and meiotic defects in oocytes via the SIRT3-SOD2-dependent pathway.

    Science.gov (United States)

    Han, Longsen; Wang, Haichao; Li, Ling; Li, Xiaoyan; Ge, Juan; Reiter, Russel J; Wang, Qiang

    2017-10-01

    Maternal obesity in humans is associated with poor outcomes across the reproductive spectrum. Emerging evidence indicates that these defects are likely attributed to factors within the oocyte. Although various molecules and pathways may contribute to impaired oocyte quality, prevention of fertility issues associated with maternal obesity is a challenge. Using mice fed a high-fat diet (HFD) as an obesity model, we document spindle disorganization, chromosome misalignment, and elevated reactive oxygen species (ROS) levels in oocytes from obese mice. Oral administration of melatonin to HFD mice not only reduces ROS generation, but also prevents spindle/chromosome anomalies in oocytes, consequently promoting the developmental potential of early embryos. Consistent with this finding, we find that melatonin supplement during in vitro maturation also markedly attenuates oxidative stress and meiotic defects in HFD oocytes. Finally, by performing morpholino knockdown and acetylation-mimetic mutant overexpression assays, we reveal that melatonin ameliorates maternal obesity-induced defective phenotypes in oocytes through the SIRT3-SOD2-dependent mechanism. In sum, our data uncover the marked beneficial effects of melatonin on oocyte quality from obese females; this opens a new area for optimizing culture system as well as fertility management. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Base case short-term Pu-oxide store. 2. Pt

    International Nuclear Information System (INIS)

    1978-08-01

    This paper describes the interim storage of plutonium oxide after its conversion from plutonium nitrate and before fabrication into fuel elements. The capacity of the store is 3 tons Pu. A description of the major handling, criticality, maintenance and physical protection philosophy is given, together with comments on the safety of the store and its impact on the environment

  1. On the Defect Chemistry, Electrical Properties and Electrochemical Performances As Solid Oxide Fuel Cell Cathode Materials of New La-(Sr/Vac)-Co-Ti-O Perovskites

    DEFF Research Database (Denmark)

    García-Alvarado, Flaviano; Gómez-Pérez, Alejandro; Pérez-Flores, Juan Carlos

    2015-01-01

    Perovskite-type oxides are well known materials that have been proposed as electrodes and electrolytes for solid oxide fuel cells (SOFCs). The structure, which is referred to the ABO3 stoichiometry, can accommodate many different transition metal ions in the B-site; its electronic conductivity...... materials with valuable properties for SOFCs. We have analysed the effect of La3+ by Sr2+ substitution and vacancies creation in several double perovskites, La2MTiO6 (M = Co, Ni, Cu). Defect chemistry and electrical behavior have been investigated in order to unveil the nature of charge carriers....... Electrochemical performances have been assessed through polarization resistance measurements. In this communication we present the results regarding La2SrTiO6 perovskites. La/Sr substitution in La2-xSrxCoTiO6-δ produces Co2+ to Co3+ oxidation while vacancies in La2-xCoTiO6-δ yield Co2+ oxidation for low A...

  2. Short-stack modeling of degradation in solid oxide fuel cells. Part I. Contact degradation

    Energy Technology Data Exchange (ETDEWEB)

    Gazzarri, J.I. [Department of Mechanical Engineering, University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, BC V6T 1Z4 (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, ON M5S 3G8 (Canada)

    2008-01-21

    As the first part of a two paper series, we present a two-dimensional impedance model of a working solid oxide fuel cell (SOFC) to study the effect of contact degradation on the impedance spectrum for the purpose of non-invasive diagnosis. The two dimensional modeled geometry includes the ribbed interconnect, and is adequate to represent co- and counter-flow configurations. Simulated degradation modes include: cathode delamination, interconnect oxidation, and interconnect-cathode detachment. The simulations show differences in the way each degradation mode impacts the impedance spectrum shape, suggesting that identification is possible. In Part II, we present a sensitivity analysis of the results to input parameter variability that reveals strengths and limitations of the method, as well as describing possible interactions between input parameters and concurrent degradation modes. (author)

  3. Short-stack modeling of degradation in solid oxide fuel cells. Part I. Contact degradation

    Science.gov (United States)

    Gazzarri, J. I.; Kesler, O.

    As the first part of a two paper series, we present a two-dimensional impedance model of a working solid oxide fuel cell (SOFC) to study the effect of contact degradation on the impedance spectrum for the purpose of non-invasive diagnosis. The two dimensional modeled geometry includes the ribbed interconnect, and is adequate to represent co- and counter-flow configurations. Simulated degradation modes include: cathode delamination, interconnect oxidation, and interconnect-cathode detachment. The simulations show differences in the way each degradation mode impacts the impedance spectrum shape, suggesting that identification is possible. In Part II, we present a sensitivity analysis of the results to input parameter variability that reveals strengths and limitations of the method, as well as describing possible interactions between input parameters and concurrent degradation modes.

  4. Activation and control of visible single defects in 4H-, 6H-, and 3C-SiC by oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Lohrmann, A.; Klein, J. R.; Prawer, S.; McCallum, J. C. [School of Physics, The University of Melbourne, Victoria 3010 (Australia); Castelletto, S. [School of Engineering, RMIT University, Melbourne, Victoria 3001 (Australia); Ohshima, T. [SemiConductor Analysis and Radiation Effects Group, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Bosi, M.; Negri, M. [IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43124 Parma (Italy); Lau, D. W. M.; Gibson, B. C. [ARC Centre of Excellence for Nanoscale BioPhotonics, School of Science, RMIT University, Melbourne, Victoria 3001 (Australia); Johnson, B. C. [ARC Centre of Excellence for Quantum Computing and Communication Technology, School of Physics, University of Melbourne, Victoria 3010 (Australia)

    2016-01-11

    In this work, we present the creation and characterisation of single photon emitters at the surface of 4H- and 6H-SiC, and of 3C-SiC epitaxially grown on silicon. These emitters can be created by annealing in an oxygen atmosphere at temperatures above 550 °C. By using standard confocal microscopy techniques, we find characteristic spectral signatures in the visible region. The excited state lifetimes are found to be in the nanosecond regime in all three polytypes, and the emission dipoles are aligned with the lattice. HF-etching is shown to effectively annihilate the defects and to restore an optically clean surface. The defects described in this work have ideal characteristics for broadband single photon generation in the visible spectral region at room temperature and for integration into nanophotonic devices.

  5. Activation and control of visible single defects in 4H-, 6H-, and 3C-SiC by oxidation

    International Nuclear Information System (INIS)

    Lohrmann, A.; Klein, J. R.; Prawer, S.; McCallum, J. C.; Castelletto, S.; Ohshima, T.; Bosi, M.; Negri, M.; Lau, D. W. M.; Gibson, B. C.; Johnson, B. C.

    2016-01-01

    In this work, we present the creation and characterisation of single photon emitters at the surface of 4H- and 6H-SiC, and of 3C-SiC epitaxially grown on silicon. These emitters can be created by annealing in an oxygen atmosphere at temperatures above 550 °C. By using standard confocal microscopy techniques, we find characteristic spectral signatures in the visible region. The excited state lifetimes are found to be in the nanosecond regime in all three polytypes, and the emission dipoles are aligned with the lattice. HF-etching is shown to effectively annihilate the defects and to restore an optically clean surface. The defects described in this work have ideal characteristics for broadband single photon generation in the visible spectral region at room temperature and for integration into nanophotonic devices

  6. Mercury Induced Biochemical Alterations As Oxidative Stress In Mugil Cephalus In Short Term Toxicity Test

    OpenAIRE

    J.S.I Rajkumar; Samuel Tennyson

    2013-01-01

    Mugil cephalus juveniles of size 2.5 ±0.6cm were exposed to mercury in short term chronic toxicity test through static renewal bioassay to detect the possible biochemical agent as biomarkers in aquatic pollution and in estuarine contamination as specific. Lipid peroxidation levels, glutathione S -transferase, catalase, reduced glutathione and acetylcholinesterase were studied as biochemical parameters. Increased thio-barbituric acid reactive substances levels were observed under exposur...

  7. Birth Defects

    Science.gov (United States)

    A birth defect is a problem that happens while a baby is developing in the mother's body. Most birth defects happen during the first 3 months of ... in the United States is born with a birth defect. A birth defect may affect how the ...

  8. Short stack modeling of degradation in solid oxide fuel cells. Part II. Sensitivity and interaction analysis

    Science.gov (United States)

    Gazzarri, J. I.; Kesler, O.

    In the first part of this two-paper series, we presented a numerical model of the impedance behaviour of a solid oxide fuel cell (SOFC) aimed at simulating the change in the impedance spectrum induced by contact degradation at the interconnect-electrode, and at the electrode-electrolyte interfaces. The purpose of that investigation was to develop a non-invasive diagnostic technique to identify degradation modes in situ. In the present paper, we appraise the predictive capabilities of the proposed method in terms of its robustness to uncertainties in the input parameters, many of which are very difficult to measure independently. We applied this technique to the degradation modes simulated in Part I, in addition to anode sulfur poisoning. Electrode delamination showed the highest robustness to input parameter variations, followed by interconnect oxidation and interconnect detachment. The most sensitive degradation mode was sulfur poisoning, due to strong parameter interactions. In addition, we simulate several simultaneous two-degradation-mode scenarios, assessing the method's capabilities and limitations for the prediction of electrochemical behaviour of SOFC's undergoing multiple simultaneous degradation modes.

  9. Short stack modeling of degradation in solid oxide fuel cells. Part II. Sensitivity and interaction analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gazzarri, J.I. [Department of Mechanical Engineering, University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, BC V6T 1Z4 (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, ON M5S 3G8 (Canada)

    2008-01-21

    In the first part of this two-paper series, we presented a numerical model of the impedance behaviour of a solid oxide fuel cell (SOFC) aimed at simulating the change in the impedance spectrum induced by contact degradation at the interconnect-electrode, and at the electrode-electrolyte interfaces. The purpose of that investigation was to develop a non-invasive diagnostic technique to identify degradation modes in situ. In the present paper, we appraise the predictive capabilities of the proposed method in terms of its robustness to uncertainties in the input parameters, many of which are very difficult to measure independently. We applied this technique to the degradation modes simulated in Part I, in addition to anode sulfur poisoning. Electrode delamination showed the highest robustness to input parameter variations, followed by interconnect oxidation and interconnect detachment. The most sensitive degradation mode was sulfur poisoning, due to strong parameter interactions. In addition, we simulate several simultaneous two-degradation-mode scenarios, assessing the method's capabilities and limitations for the prediction of electrochemical behaviour of SOFC's undergoing multiple simultaneous degradation modes. (author)

  10. Selective surface oxidation and segregation upon short term annealing of model alloys and industrial steel grades

    Energy Technology Data Exchange (ETDEWEB)

    Swaminathan, S.

    2007-07-01

    Segregation and selective oxidation phenomena of minor alloying elements during annealing of steel sheets lead to the formation of bare spots after hot-dip galvanizing. This thesis highlights the influence of annealing conditions and the effect of alloying elements on the selective oxidation in model alloys and some industrial steel grades. Model alloys of binary (Fe-2Si, Fe-2Mn, Fe-0.8Cr), ternary (Fe-2Mn-2Si, Fe-2Mn-0.8Cr, Fe-1Mn-0.8Cr, Fe-1Si-0.8Cr, Fe-2Si-0.8Cr) and quarternary (Fe-2Mn-2Si-0.8Cr) systems were studied. In the case of steels, standard grade interstitial free (IF) steels and experimental grade tensile strength 1000 MPa steel were investigated. All specimens were annealed at 820 C in N{sub 2}-5%H{sub 2} gas atmospheres with the wide range of dew points (i.e. -80 to 0 C). The surface chemistry after annealing and its wettability with liquid Zn have been correlated as a function of dew points by simulating the hot-dip galvanizing process at laboratory scale. (orig.)

  11. Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

    International Nuclear Information System (INIS)

    Kunj, Saurabh; Sreenivas, K.

    2016-01-01

    Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O_2/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

  12. Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

    Science.gov (United States)

    Kunj, Saurabh; Sreenivas, K.

    2016-05-01

    Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O2/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

  13. Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kunj, Saurabh, E-mail: saurabhkunj22@gmail.com; Sreenivas, K. [Department of Physics & Astrophysics, University of Delhi, Delhi-110007 (India)

    2016-05-23

    Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O{sub 2}/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

  14. Presentation of a novel model of chitosan- polyethylene oxide-nanohydroxyapatite nanofibers together with bone marrow stromal cells to repair and improve minor bone defects

    Directory of Open Access Journals (Sweden)

    Asgar Emamgholi

    2015-09-01

    Full Text Available Objective(s:Various methods for repairing bone defects are presented. Cell therapy is one of these methods. Bone marrow stromal cells (BMSCs seem to be suitable for this purpose. On the other hand, lots of biomaterials are used to improve and repair the defect in the body, so in this study we tried to produce a similar structure to the bone by the chitosan and hydroxyapatite. Materials and Methods: In this study, the solution of chitosan-nanohydroxyapatite-polyethylene oxide (PEO Nanofibers was produced by electrospinning method, and then the BMSCs were cultured on this solution. A piece of chitosan-nanohydroxyapatite Nanofibers with BMSCs was placed in a hole with the diameter of 1 mm at the distal epiphysis of the rat femur. Then the biomechanical and radiographic studies were performed. Results: Biomechanical testing results showed that bone strength was significantly higher in the Nanofiber/BMSCs group in comparison with control group. Also the bone strength in nanofiber/BMSCs group was significant, but in nanofiber group was nearly significant. Radiographic studies also showed that the average amount of callus formation (radio opacity in nanofiber and control group was not significantly different. The callus formation in nanofiber/BMSCs group was increased compared to the control group, and it was not significant in the nanofiber group. Conclusion: Since chitosan-nanohydroxyapatite nanofibers with BMSCs increases the rate of bone repair, the obtained cell-nanoscaffold shell can be used in tissue engineering and cell therapy, especially for bone defects.

  15. Evolution of Defect Structures and Deep Subgap States during Annealing of Amorphous In-Ga-Zn Oxide for Thin-Film Transistors

    Science.gov (United States)

    Jia, Junjun; Suko, Ayaka; Shigesato, Yuzo; Okajima, Toshihiro; Inoue, Keiko; Hosomi, Hiroyuki

    2018-01-01

    We investigate the evolution behavior of defect structures and the subgap states in In-Ga-Zn oxide (IGZO) films with increasing postannealing temperature by means of extended x-ray absorption fine-structure (EXAFS) measurements, positron annihilation lifetime spectroscopy (PALS), and cathodoluminescence (CL) spectroscopy, aiming to understand the relationship between defect structures and subgap states. EXAFS measurements reveal the varied oxygen coordination numbers around cations during postannealing and confirm two types of point defects, namely, excess oxygen around Ga atoms and oxygen deficiency around In and/or Zn atoms. PALS suggests the existence of cation-vacancy (VM )-related clusters with neutral or negative charge in both amorphous and polycrystalline IGZO films. CL spectra show a main emission band at approximately 1.85 eV for IGZO films, and a distinct shoulder located at about 2.15 eV for IGZO films postannealed above 600 °C . These two emission bands are assigned to a recombination between the electrons in the conduction band and/or in the shallow donor levels near the conduction band and the acceptors trapped above the valence-band maximum. The shallow donors are attributed to the oxygen deficiency, and the acceptors are thought to possibly arise from the excess oxygen or the VM-related clusters. These results open up an alternative route for understanding the device instability of amorphous IGZO-based thin-film transistors, especially the presence of the neutral or negatively charged VM-related clusters in amorphous IGZO films.

  16. An Indium-Free Anode for Large-Area Flexible OLEDs: Defect-Free Transparent Conductive Zinc Tin Oxide

    NARCIS (Netherlands)

    Morales-Masis, M.; Dauzou, F.; Jeangros, Q.; Dabirian, A.; Lifka, H.; Gierth, R.; Ruske, M.; Moet, D.; Hessler-Wyser, A.; Ballif, C.

    2016-01-01

    Flexible large-area organic light-emitting diodes (OLEDs) require highly conductive and transparent anodes for efficient and uniform light emission. Tin-doped indium oxide (ITO) is the standard anode in industry. However, due to the scarcity of indium, alternative anodes that eliminate its use are

  17. Measurement and modelling of the defect chemistry and transport properties of ceramic oxide mixed ionic and electronic conductors

    DEFF Research Database (Denmark)

    Dalslet, Bjarke Thomas

    2008-01-01

    The subject of this thesis is ceramic mixed ionic and electronic conductors (MIECs). MIECs have potential uses, such as solid oxygen permeation membranes, as catalysts, and as components in fuel cells. The MIECs examined in this thesis are all oxide ion conducting materials. This thesis describes...

  18. Chemotherapeutic-Induced Cardiovascular Dysfunction: Physiological Effects, Early Detection—The Role of Telomerase to Counteract Mitochondrial Defects and Oxidative Stress

    Science.gov (United States)

    Quryshi, Nabeel; Norwood Toro, Laura E.; Ait-Aissa, Karima; Kong, Amanda; Beyer, Andreas M.

    2018-01-01

    Although chemotherapeutics can be highly effective at targeting malignancies, their ability to trigger cardiovascular morbidity is clinically significant. Chemotherapy can adversely affect cardiovascular physiology, resulting in the development of cardiomyopathy, heart failure and microvascular defects. Specifically, anthracyclines are known to cause an excessive buildup of free radical species and mitochondrial DNA damage (mtDNA) that can lead to oxidative stress-induced cardiovascular apoptosis. Therefore, oncologists and cardiologists maintain a network of communication when dealing with patients during treatment in order to treat and prevent chemotherapy-induced cardiovascular damage; however, there is a need to discover more accurate biomarkers and therapeutics to combat and predict the onset of cardiovascular side effects. Telomerase, originally discovered to promote cellular proliferation, has recently emerged as a potential mechanism to counteract mitochondrial defects and restore healthy mitochondrial vascular phenotypes. This review details mechanisms currently used to assess cardiovascular damage, such as C-reactive protein (CRP) and troponin levels, while also unearthing recently researched biomarkers, including circulating mtDNA, telomere length and telomerase activity. Further, we explore a potential role of telomerase in the mitigation of mitochondrial reactive oxygen species and maintenance of mtDNA integrity. Telomerase activity presents a promising indicator for the early detection and treatment of chemotherapy-derived cardiac damage. PMID:29534446

  19. Defect Chemistry, Electrical Properties, and Evaluation of New Oxides Sr2 CoNb1-x Tix O6-δ (0≤x≤1) as Cathode Materials for Solid Oxide Fuel Cells.

    Science.gov (United States)

    Azcondo, María Teresa; Yuste, Mercedes; Pérez-Flores, Juan Carlos; Muñoz-Gil, Daniel; García-Martín, Susana; Muñoz-Noval, Alvaro; Orench, Inés Puente; García-Alvarado, Flaviano; Amador, Ulises

    2017-07-21

    The perovskite series Sr 2 CoNb 1-x Ti x O 6-δ (0≤x≤1) was investigated in the full compositional range to assess its potential as cathode material for solid oxide fuel cell (SOFC). The variation of transport properties and thus, the area specific resistances (ASR) are explained by a detailed investigation of the defect chemistry. Increasing the titanium content from x=0-1 produces both oxidation of Co 3+ to Co 4+ (from 0 up to 40 %) and oxygen vacancies (from 6.0 to 5.7 oxygen atom/formula unit), although each charge compensation mechanism predominates in different compositional ranges. Neutron diffraction reveals that samples with high Ti-contents lose a significant amount of oxygen upon heating above 600 K. Oxygen is partially recovered upon cooling as the oxygen release and uptake show noticeably different kinetics. The complex defect chemistry of these compounds, together with the compositional changes upon heating/cooling cycles and atmospheres, produce a complicated behavior of electrical conductivity. Cathodes containing Sr 2 CoTiO 6-δ display low ASR values, 0,13 Ω cm 2 at 973 K, comparable to those of the best compounds reported so far, being a very promising cathode material for SOFC. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Acrolein coupling on reduced TiO 2(1 1 0): The effect of surface oxidation and the role of subsurface defects

    Science.gov (United States)

    Benz, Lauren; Haubrich, Jan; Quiller, Ryan G.; Friend, Cynthia M.

    2009-04-01

    Reactions of acrolein, water, and oxygen with the vacuum-reduced surface of TiO 2(1 1 0) are reported in a temperature programmed reaction study of the interaction of an aldehydic pollutant with a reducible metal oxide. A total of 25% of the acrolein that binds to the surface is converted to products. Notably, carbon-carbon coupling occurs with 86% selectivity for formation of C 6 products: C 6H 8, identified as 1,3-cyclohexadiene, in a peak at 500 K and benzene immediately thereafter at 530 K. Acrolein is evolved from the surface in three peaks: a peak independent of coverage at 495 K, attributed to decomposition of an intermediate that is partly converted to C 6H 8; a coverage-dependent peak that shifts from 370 K (low coverage) to 260 K (high coverage), which is attributed to adsorption at 5-fold coordinated Ti sites; and a multilayer state at 160 K. Water and acrolein compete for 5-fold coordinated titanium sites when dosed sequentially. The addition of water also opens a new reaction pathway, leading to the hydrogenation of acrolein to form propanal. Water has no effect on the yield of 1,3-cyclohexadiene. Exposure of the surface to oxygen prior to acrolein dosing quenches the evolution of acrolein at 495 K and concurrently eliminates the coupling. From these results, we propose that reduced subsurface defects such as titanium ion interstitials play a role in the reactions observed here. The notion that subsurface defects may contribute to the reactivity of organic molecules over reducible oxide substrates may prove to be general.

  1. Short-Term Systemic Effects of Nose-Only Cigarette Smoke Exposure in Mice: Role of Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Abderrahim Nemmar

    2013-01-01

    Full Text Available Background/Aims: Long–term cigarette smoking (CS is a major risk factor for respiratory and cardiovascular diseases, and is also known to adversely affect other organs. However, data on the systemic effects of short-term CS exposure (STCSE are scarce. Presently, using a nose-only exposure system, we evaluated the systemic effects of STCSE in mice. Methods: We assessed the effects of CS generated by 9 consecutive cigarettes per day for 4 days in a nose-only exposure system on cardiovascular, hepatic and renal endpoints evaluated on day 5 in mice. Control mice were exposed to air only. Results: CS significantly increased systolic blood pressure and decreased total nitric oxide plasma concentration. Circulating platelets and erythrocyte numbers were also increased. However, STCSE did not significantly increase thrombosis in pial arterioles and venules. STCSE significantly raised plasma alanine aminotransferase and gamma glutamyl transpeptidase activities, but did not affect urea or creatinine concentrations. Interestingly, while STCSE enhanced the production of reactive oxygen species in heart and kidney and lipid peroxidation in heart, liver and kidneys, it also enhanced the antioxidant activity of superoxide dismutase, probably indicating that STCSE causes adaptive reactions to counterbalance the potentially damaging action of oxygen radicals induced by STCSE. Conclusion: These results suggest that STCSE causes blood pressure increase, hepatotoxicity and oxidative stress in the heart, liver and the kidneys. These data provide information on the initial steps leading to the systemic effects of STCSE, a stage at which the diseases may likely be reversed.

  2. Radiation-enhanced short channel effects due to multi-dimensional influence from charge at trench isolation oxides

    International Nuclear Information System (INIS)

    Youk, G.U.; Khare, P.S.; Schrimpf, R.D.; Massengill, L.W.; Galloway, K.F.

    1999-01-01

    Radiation enhanced drain induced barrier lowering (DIBL) was experimentally observed and verified by 3-D simulations for submicron devices with trench isolation oxides. Submicron MOSFETs with shallow trench isolation were exposed to total-ionizing-dose radiation. Prior to irradiation, the devices exhibited near-ideal current-voltage characteristics, with no significant short-channel effects for as-drawn gate lengths of 0.4 microm. Following irradiation, the off-state leakage current increased significantly for total doses above about 650 krad(SiO 2 ). In addition, the irradiated devices exhibited DIBL that increased the drain current by 5--10x for a gate length of 0.4 microm (the nominal minimum gate length for this process) and much more for slightly shorter devices (0.35 microm). The increase in the off-state leakage current and the accompanying DIBL are shown to be associated with a parasitic field-effect transistor that is present at the edge of the shallow trench. Three-dimensional simulations are used to illustrate the effect. Simulations show that trapped charge at the trench sidewalls enhance the DIBL by depleting the edges of the channel. Radiation-induced charge may decrease the effectiveness of short-channel engineering

  3. Short-Term Fructose Feeding Induces Inflammation and Oxidative Stress in the Hippocampus of Young and Adult Rats.

    Science.gov (United States)

    Cigliano, Luisa; Spagnuolo, Maria Stefania; Crescenzo, Raffaella; Cancelliere, Rosa; Iannotta, Lucia; Mazzoli, Arianna; Liverini, Giovanna; Iossa, Susanna

    2018-04-01

    The drastic increase in the consumption of fructose encouraged the research to focus on its effects on brain physio-pathology. Although young and adults differ largely by their metabolic and physiological profiles, most of the previous studies investigated brain disturbances induced by long-term fructose feeding in adults. Therefore, we investigated whether a short-term consumption of fructose (2 weeks) produces early increase in specific markers of inflammation and oxidative stress in the hippocampus of young and adult rats. After the high-fructose diet, plasma lipopolysaccharide and tumour necrosis factor (TNF)-alpha were found significantly increased in parallel with hippocampus inflammation, evidenced by a significant rise in TNF-alpha and glial fibrillar acidic protein concentrations in both the young and adult groups. The fructose-induced inflammatory condition was associated with brain oxidative stress, as increased levels of lipid peroxidation and nitro-tyrosine were detected in the hippocampus. The degree of activation of the protein kinase B, extracellular signal-regulated kinase 1/2, and insulin receptor substrate 1 pathways found in the hippocampus after fructose feeding indicates that the detrimental effects of the fructose-rich diet might largely depend on age. Mitochondrial function in the hippocampus, together with peroxisome proliferator-activated receptor gamma coactivator 1-alpha content, was found significantly decreased in fructose-treated adult rats. In vitro studies with BV-2 microglial cells confirmed that fructose treatment induces TNF-alpha production as well as oxidative stress. In conclusion, these results suggest that unbalanced diet, rich in fructose, may be highly deleterious in young people as in adults and must be strongly discouraged for the prevention of diet-associated neuroinflammation and neurological diseases.

  4. A case of osteomalacia due to deranged mineral balance caused by saccharated ferric oxide and short-bowel syndrome: A case report.

    Science.gov (United States)

    Nomoto, Hiroshi; Miyoshi, Hideaki; Nakamura, Akinobu; Nagai, So; Kitao, Naoyuki; Shimizu, Chikara; Atsumi, Tatsuya

    2017-09-01

    Saccharated ferric oxide has been shown to lead to elevation of fibroblast growth factor 23, hypophosphatemia, and, consequently, osteomalacia. Moreover, mineral imbalance is often observed in patients with short-bowel syndrome to some degree. A 62-year-old woman with short-bowel syndrome related with multiple resections of small intestines due to Crohn disease received regular intravenous administration of saccharated ferric oxide. Over the course of treatment, she was diagnosed with tetany, which was attributed to hypocalcemia. Additional assessments of the patient revealed not only hypocalcemia, but also hypophosphatemia, hypomagnesemia, osteomalacia, and a high concentration of fibroblast growth factor 23 (314 pg/mL). We diagnosed her with mineral imbalance-induced osteomalacia due to saccharated ferric oxide and short-bowel syndrome. Magnesium replacement therapy and discontinuation of saccharated ferric oxide alone. These treatments were able to normalize her serum mineral levels and increase her bone mineral density. This case suggests that adequate evaluation of serum minerals, including phosphate and magnesium, during saccharated ferric oxide administration may be necessary, especially in patients with short-bowel syndrome.

  5. Intrinsic and defect related luminescence in double oxide films of Al–Hf–O system under soft X-ray and VUV excitation

    Energy Technology Data Exchange (ETDEWEB)

    Pustovarov, V.A., E-mail: vpustovarov@bk.ru [Ural Federal University, 19 Mira Street, 620002 Yekaterinburg (Russian Federation); Smirnova, T.P.; Lebedev, M.S. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Science, Novosibirsk 630090 (Russian Federation); Gritsenko, V.A. [Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Novosibirsk National Research University, 2 Pirogova Street, 630090 Novosibirsk (Russian Federation); Kirm, M. [Institute of Physics, University of Tartu, 14c Ravila, 50411 Tartu (Estonia)

    2016-02-15

    Low temperature time-resolved luminescence spectra in the region of 2.5–9.5 eV under soft X-ray excitation as well as time-resolved luminescence excitation spectra in the UV–VUV region (3.7–12 eV) of solid solutions Al{sub x}Hf{sub y}O{sub 1−x−y} thin films were investigated. The values of x and Al/Hf ratio were determined from X-ray photoelectron srectroscopy data. Hafnia films and films mixed with alumina were grown in a flow-type chemical vapor deposition reactor with argon as a carrier gas. In addition, pure alumina films were prepared by the atomic layer deposition method. A strong emission band with the peak position at 4.4 eV and with the decay time in the μs-range was revealed for pure hafnia films. The emission peak at 7.74 eV with short nanosecond decay kinetics was observed in the luminescence spectra for pure alumina films. These emission bands were ascribed to the radiative decay of self-trapped excitons (an intrinsic luminescence) in pure HfO{sub 2} and Al{sub 2}O{sub 3} films, respectively. Along with intrinsic host emission, defect related luminescence bands with a larger Stokes shift were observed. In the emission spectra of the solid solution films (x=4; 17; 20 at%) the intrinsic emission bands are quenched and only the luminescence of defects (an anion vacancies) was observed. Based on transformation of the luminescence spectra and ns-luminescence decay kinetics, as well as changes in the time-resolved luminescence and luminescence excitation spectra, the relaxation processes in the films of solid solution are discussed. - Highlights: • Low temperature time−resolved PL spectra were studied in a broad range (1.5−9.5 eV). • We carried out a luminescent control of point defects (anion vacancies) and self−trapped excitons. • We observed photoluminescence of excitons bound on defects. • We observed changes of photoluminescence properties with varying ratio components.

  6. Catalytic Oxidation of CO and Soot over Ce-Zr-Pr Mixed Oxides Synthesized in a Multi-Inlet Vortex Reactor: Effect of Structural Defects on the Catalytic Activity.

    Science.gov (United States)

    Bensaid, Samir; Piumetti, Marco; Novara, Chiara; Giorgis, Fabrizio; Chiodoni, Angelica; Russo, Nunzio; Fino, Debora

    2016-12-01

    In the present work, ceria, ceria-zirconia (Ce = 80 at.%, Zr = 20 at.%), ceria praseodymia (Ce = 80 at.%, Pr = 20 at.%) and ceria-zirconia-praseodymia catalysts (Ce = 80 at.%, Zr = 10 at.% and Pr = 10 at.%) have been prepared by the multi-inlet vortex reactor (MIVR). For each set of samples, two inlet flow rates have been used during the synthesis (namely, 2 ml min -1 , and 20 ml min -1 ) in order to obtain different particle sizes. Catalytic activity of the prepared materials has been investigated for CO and soot oxidation reactions. As a result, when the catalysts exhibit similar crystallite sizes (in the 7.7-8.8 nm range), it is possible to observe a direct correlation between the O v /F 2g vibrational band intensity ratios and the catalytic performance for the CO oxidation. This means that structural (superficial) defects play a key role for this process. The incorporation of Zr and Pr species into the ceria lattice increases the population of structural defects, as measured by Raman spectroscopy, according to the order: CeO 2  oxidation activity for these catalysts, in contrast with nanostructured ones (e.g., Ce-Zr-O nanopolyhedra, Ce-Pr-O nanocubes) described elsewhere (Andana et al. Appl. Catal. B 197: 125-137, 2016; Piumetti et al., Appl Catal B 180: 271-282, 2016).

  7. A short history of nitroglycerine and nitric oxide in pharmacology and physiology.

    Science.gov (United States)

    Marsh, N; Marsh, A

    2000-04-01

    1. Nitroglycerine (NG) was discovered in 1847 by Ascanio Sobrero in Turin, following work with Theophile-Jules Pelouze. Sobrero first noted the 'violent headache' produced by minute quantities of NG on the tongue. 2. Constantin Hering, in 1849, tested NG in healthy volunteers, observing that headache was caused with 'such precision'. Hering pursued NG ('glonoine') as a homeopathic remedy for headache, believing that its use fell within the doctrine of 'like cures like'. 3. Alfred Nobel joined Pelouze in 1851 and recognized the potential of NG. He began manufacturing NG in Sweden, overcoming handling problems with his patent detonator. Nobel suffered acutely from angina and was later to refuse NG as a treatment. 4. During the mid-19th century, scientists in Britain took an interest in the newly discovered amyl nitrite, recognized as a powerful vasodilator. Lauder Brunton, the father of modern pharmacology, used the compound to relieve angina in 1867, noting the pharmacological resistance to repeated doses. 5. William Murrell first used NG for angina in 1876, although NG entered the British Pharmacopoeia as a remedy for hypertension. William Martindale, the pharmaceutical chemist, prepared '...a more stable and portable preparation': 1/100th of a grain in chocolate. 6. In the early 20th century, scientists worked on in vitro actions of nitrate-containing compounds although little progress was made towards understanding the cellular mode of action. 7. The NG industry flourished from 1900, exposing workers to high levels of organic nitrites; the phenomena of nitrate tolerance was recognized by the onset of 'Monday disease' and of nitrate-withdrawal/overcompensation by 'Sunday Heart Attacks'. 8. Ferid Murad discovered the release of nitric oxide (NO) from NG and its action on vascular smooth muscle (in 1977). Robert Furchgott and John Zawadski recognized the importance of the endothelium in acetylcholine-induced vasorelaxation (in 1980) and Louis Ignarro and Salvador

  8. Disrupted fat distribution and composition due to medium-chain triglycerides in mice with a β-oxidation defect.

    Science.gov (United States)

    Tucci, Sara; Flögel, Ulrich; Sturm, Marga; Borsch, Elena; Spiekerkoetter, Ute

    2011-08-01

    Because of the enhanced recognition of inherited long-chain fatty acid oxidation disorders by worldwide newborn screening programs, an increasing number of asymptomatic patients receive medium-chain triglyceride (MCT) supplements to prevent the development of cardiomyopathy and myopathy. MCT supplementation has been recognized as a safe dietary intervention, but long-term observations into later adulthood are still not available. We investigated the consequences of a prolonged MCT diet on abdominal fat distribution and composition and on liver fat. Mice with very-long-chain acyl-coenzyme A dehydrogenase deficiency (VLCAD(-/-)) were supplemented for 1 y with a diet in which MCTs replaced long-chain triglycerides without increasing the total fat content. The dietary effects on abdominal fat accumulation and composition were analyzed by in vivo (1)H- and (13)C-magnetic resonance spectroscopy (9.4 Tesla). After 1 y of MCT supplementation, VLCAD(-/-) mice accumulated massive visceral fat and had a dramatic increase in the concentration of serum free fatty acids. Furthermore, we observed a profound shift in body triglyceride composition, ie, concentrations of physiologically important polyunsaturated fatty acids dramatically decreased. (1)H-Magnetic resonance spectroscopy analysis and histologic evaluation of the liver also showed pronounced fat accumulation and marked oxidative stress. Although the MCT-supplemented diet has been reported to prevent the development of cardiomyopathy and skeletal myopathy in fatty acid oxidation disorders, our data show that long-term MCT supplementation results in a severe clinical phenotype similar to that of nonalcoholic steatohepatitis and the metabolic syndrome.

  9. Defective bone formation and anabolic response to exogenous estrogen in mice with targeted disruption of endothelial nitric oxide synthase.

    Science.gov (United States)

    Armour, K E; Armour, K J; Gallagher, M E; Gödecke, A; Helfrich, M H; Reid, D M; Ralston, S H

    2001-02-01

    Nitric oxide (NO) is a pleiotropic signaling molecule that is produced by bone cells constitutively and in response to diverse stimuli such as proinflammatory cytokines, mechanical strain, and sex hormones. Endothelial nitric oxide synthase (eNOS) is the predominant NOS isoform expressed in bone, but its physiological role in regulating bone metabolism remains unclear. Here we studied various aspects of bone metabolism in female mice with targeted disruption of the eNOS gene. Mice with eNOS deficiency (eNOS KO) had reduced bone mineral density, and cortical thinning when compared with WT controls and histomorphometric analysis of bone revealed profound abnormalities of bone formation, with reduced osteoblast numbers, surfaces and mineral apposition rate. Studies in vitro showed that osteoblasts derived from eNOS KO mice had reduced rates of growth when compared with WT and were less well differentiated as reflected by lower levels of alkaline phosphatase activity. Mice with eNOS deficiency lost bone normally following ovariectomy but exhibited a significantly blunted anabolic response to high dose exogenous estrogen. We conclude that the eNOS pathway plays an essential role in regulating bone mass and bone turnover by modulating osteoblast function.

  10. In Healthy Young Men, a Short Exhaustive Exercise Alters the Oxidative Stress Only Slightly, Independent of the Actual Fitness

    Directory of Open Access Journals (Sweden)

    Maya Finkler

    2016-01-01

    Full Text Available The aim of the present study was to evaluate the apparent disagreement regarding the effect of a typical cycling progressive exercise, commonly used to assess VO2max, on the kinetics of ex vivo copper induced peroxidation of serum lipids. Thirty-two (32 healthy young men, aged 24–30 years, who do not smoke and do not take any food supplements, participated in the study. Blood was withdrawn from each participant at three time points (before the exercise and 5 minutes and one hour after exercise. Copper induced peroxidation of sera made of the blood samples was monitored by spectrophotometry. For comparison, we also assayed TBARS concentration and the activity of oxidation-related enzymes. The physical exercise resulted in a slight and reversible increase of TBARS and slight changes in the activities of the studied antioxidant enzymes and the lag preceding peroxidation did not change substantially. Most altered parameters returned to baseline level one hour after exercise. Notably, the exercise-induced changes in OS did not correlate with the physical fitness of the subjects, as evaluated in this study (VO2max = 30–60 mL/min/kg. We conclude that in healthy young fit men a short exhaustive exercise alters only slightly the OS, independent of the actual physical fitness.

  11. In Healthy Young Men, a Short Exhaustive Exercise Alters the Oxidative Stress Only Slightly, Independent of the Actual Fitness.

    Science.gov (United States)

    Finkler, Maya; Hochman, Ayala; Pinchuk, Ilya; Lichtenberg, Dov

    2016-01-01

    The aim of the present study was to evaluate the apparent disagreement regarding the effect of a typical cycling progressive exercise, commonly used to assess VO2max, on the kinetics of ex vivo copper induced peroxidation of serum lipids. Thirty-two (32) healthy young men, aged 24-30 years, who do not smoke and do not take any food supplements, participated in the study. Blood was withdrawn from each participant at three time points (before the exercise and 5 minutes and one hour after exercise). Copper induced peroxidation of sera made of the blood samples was monitored by spectrophotometry. For comparison, we also assayed TBARS concentration and the activity of oxidation-related enzymes. The physical exercise resulted in a slight and reversible increase of TBARS and slight changes in the activities of the studied antioxidant enzymes and the lag preceding peroxidation did not change substantially. Most altered parameters returned to baseline level one hour after exercise. Notably, the exercise-induced changes in OS did not correlate with the physical fitness of the subjects, as evaluated in this study (VO2max = 30-60 mL/min/kg). We conclude that in healthy young fit men a short exhaustive exercise alters only slightly the OS, independent of the actual physical fitness.

  12. Defective TiO2 with oxygen vacancies: synthesis, properties and photocatalytic applications

    Science.gov (United States)

    Pan, Xiaoyang; Yang, Min-Quan; Fu, Xianzhi; Zhang, Nan; Xu, Yi-Jun

    2013-04-01

    Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties of TiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO2. In particular, photocatalytic applications with regard to defective TiO2 are outlined. In addition, we offer some perspectives on the challenge and new direction for future research in this field. We hope that this tutorial minireview would provide some useful contribution to the future design and fabrication of defective semiconductor-based nanomaterials for diverse photocatalytic applications.Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the

  13. High-resolution Kendrick Mass Defect Analysis of Poly(ethylene oxide)-based Non-ionic Surfactants and Their Degradation Products.

    Science.gov (United States)

    Fouquet, Thierry; Shimada, Haruo; Maeno, Katsuyuki; Ito, Kanako; Ozeki, Yuka; Kitagawa, Shinya; Ohtani, Hajime; Sato, Hiroaki

    2017-09-01

    Matrix assisted laser desorption ionization (MALDI) high-resolution mass spectrometry (HRMS) and the recently introduced high-resolution Kendrick mass defect (HRKMD) analysis are combined to thoroughly characterize non-ionic surfactants made of a poly(ethylene oxide) (PEO) core capped by esters of fatty acids. A PEO monostearate surfactant is first analyzed as a proof of principle of the HRKMD analysis conducted with a fraction of EO as the base unit (EO/X with X being an integer) in lieu of EO for a regular KMD analysis. Data visualization is greatly enhanced and the distributions detected in the MALDI mass spectrum are assigned to a pristine (H, OH)-PEO as well as mono- and di-esterified PEO chains with palmitate and stearate end-groups in HRKMD plots computed with EO/45. The MALDI-HRMS/HRKMD analysis is then successfully applied to the more complex case of ethoxylated hydrogenated castor oil (EHCO) found to contain a large number of hydrogenated ricinoleate moieties (up to 14) in its HRKMD plot computed with EO/43, departing from the expected triglyceride structure. The exhaustiveness of the MALDI-HRMS/HRKMD strategy is validated by comparing the so-obtained fingerprints with results from alternative techniques (electrospray ionization MS, size exclusion and liquid adsorption chromatography, ion mobility spectrometry). Finally, aged non-ionic surfactants formed upon hydrolytic degradation are analyzed by MALDI-HRMS/HRKMD to easily assign the degradation products and infer the associated degradation routes. In addition to the hydrolysis of the ester groups observed for EHCO, chain scissions and new polar end-groups are observed in the HRKMD plot of PEO monostearate arising from a competitive oxidative ageing.

  14. Reactivity of a reduced metal oxide surface: hydrogen, water and carbon monoxide adsorption on oxygen defective rutile TiO 2( 1 1 0 )

    Science.gov (United States)

    Menetrey, M.; Markovits, A.; Minot, C.

    2003-02-01

    The reactivity at reduced surface differs from that on the stoichiometric perfect surfaces. This does not originate uniquely from the modification of the coordination; electron count also is determining. The general trend is a decrease of the heat of adsorption on the metal cations. The reactivity decreases at sites in the vicinity of the defects due to the reduction induced by the O vacancies. At the defect site the decrease is less pronounced for H, H 2, CO and molecular H 2O. In the case of H 2O dissociative adsorption, the defect site is more reactive than the perfect surface. Thus, a hydration converting the defective-reduced TiO 2 to the hydrogenated non-defective-reduced surface is easy. The resulting structure possesses surface hydroxyl groups. It is probably the easiest way to form the hydrogenated non-defective surface. On TiO 2, the defective surface requires very anhydrous conditions.

  15. Who named the quantum defect?

    International Nuclear Information System (INIS)

    Rau, A.R.P.; Inokuti, M.

    1997-01-01

    The notion of the quantum defect is important in atomic and molecular spectroscopy and also in unifying spectroscopy with collision theory. In the latter context, the quantum defect may be viewed as an ancestor of the phase shift. However, the origin of the term quantum defect does not seem to be explained in standard textbooks. It occurred in a 1921 paper by Schroedinger, preceding quantum mechanics, yet giving the correct meaning as an index of the short-range interactions with the core of an atom. The authors present the early history of the quantum-defect idea, and sketch its recent developments

  16. Changes in oxidative stress parameters in relation to age, growth and reproduction in the short-lived catarina scallop Argopecten ventricosus reared in its natural environment.

    Science.gov (United States)

    Guerra, C; Zenteno-Savín, T; Maeda-Martínez, A N; Philipp, E E R; Abele, D

    2012-08-01

    Increase in oxidative damage and decrease in cellular maintenance is often associated with aging, but, in marine ectotherms, both processes are also strongly influenced by somatic growth, maturation and reproduction. In this study, we used a single cohort of the short-lived catarina scallop Argopecten ventricosus, to investigate the effects of somatic growth, reproduction and aging on oxidative damage parameters (protein carbonyls, TBARS and lipofuscin) and cellular maintenance mechanisms (antioxidant activity and apoptosis) in scallops, caged in their natural environment. The concentrations of protein carbonyls and TBARS increased steeply during the early period of fast growth and during reproduction in one-year-old scallops. However, oxidative damage was transient, and apoptotic cell death played a pivotal role in eliminating damage in gill, mantle and muscle tissues of young scallops. Animals were able to reproduce again in the second year, but the reduced intensity of apoptosis impaired subsequent removal of damaged cells. In late survivors low antioxidant capacity and apoptotic activity together with a fast accumulation of the age pigment lipofuscin was observed. Rates of oxygen consumption and oxidative stress markers were strongly dependent on somatic growth and reproductive state but not on temperature. Compared to longer-lived bivalves, A. ventricosus seems more susceptible to oxidative stress with higher tissue-specific protein carbonyl levels and fast accumulation of lipofuscin in animals surviving the second spawning. Superoxide dismutase activity and apoptotic cell death intensity were however higher in this short-lived scallop than in longer-lived bivalves. The life strategy of this short-lived and intensely predated scallop supports rapid somatic growth and fitness as well as early maturation at young age at the cost of fast cellular degradation in second year scallops. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. SHORT COMMUNICATION

    African Journals Online (AJOL)

    a

    ______. *Corresponding author. E-mail: vani_chem@yahoo.com. SHORT COMMUNICATION. OXIDATION OF L-CYSTINE BY CHROMIUM(VI) - A KINETIC STUDY. Kalyan Kumar Adari, Annapurna Nowduri and Vani Parvataneni*. Department of Inorganic and Analytical Chemistry, School of Chemistry, Andhra University,.

  18. Effects of short term and long term Extremely Low Frequency Magnetic Field on depressive disorder in mice: Involvement of nitric oxide pathway.

    Science.gov (United States)

    Madjid Ansari, Alireza; Farzampour, Shahrokh; Sadr, Ali; Shekarchi, Babak; Majidzadeh-A, Keivan

    2016-02-01

    Previous reports on the possible effects of Extremely Low Frequency Magnetic Fields (ELF MF) on mood have been paradoxical in different settings while no study has yet been conducted on animal behavior. In addition, it was shown that ELF MF exposure makes an increase in brain nitric oxide level. Therefore, in the current study, we aimed to assess the possible effect(s) of ELF MF exposure on mice Forced Swimming Test (FST) and evaluate the probable role of the increased level of nitric oxide in the observed behavior. Male adult mice NMRI were recruited to investigate the short term and long term ELF MF exposure (0.5 mT and 50 Hz, single 2h and 2 weeks 2h a day). Locomotor behavior was assessed by using open-field test (OFT) followed by FST to evaluate the immobility time. Accordingly, NΩ-nitro-l-arginine methyl ester 30 mg/kg was used to exert anti-depressant like effect. According to the results, short term exposure did not alter the immobility time, whereas long term exposure significantly reduces immobility time (pmice, whereas short term exposure has no significant effect. Also, reversing the anti-depressant activity of L-NAME indicates a probable increase in the brain nitric oxide. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Effects of short-term Western diet on cerebral oxidative stress and diabetes related factors in APP x PS1 knock-in mice.

    Science.gov (United States)

    Studzinski, Christa M; Li, Feng; Bruce-Keller, Annadora J; Fernandez-Kim, Sun Ok; Zhang, Le; Weidner, Adam M; Markesbery, William R; Murphy, M Paul; Keller, Jeffrey N

    2009-02-01

    A chronic high fat Western diet (WD) promotes a variety of morbidity factors although experimental evidence for short-term WD mediating brain dysfunction remains to be elucidated. The amyloid precursor protein and presenilin-1 (APP x PS1) knock-in mouse model has been demonstrated to recapitulate some key features of Alzheimer's disease pathology, including amyloid-beta (Abeta) pathogenesis. In this study, we placed 1-month-old APP x PS1 mice and non-transgenic littermates on a WD for 4 weeks. The WD resulted in a significant elevation in protein oxidation and lipid peroxidation in the brain of APP x PS1 mice relative to non-transgenic littermates, which occurred in the absence of increased Abeta levels. Altered adipokine levels were also observed in APP x PS1 mice placed on a short-term WD, relative to non-transgenic littermates. Taken together, these data indicate that short-term WD is sufficient to selectively promote cerebral oxidative stress and metabolic disturbances in APP x PS1 knock-in mice, with increased oxidative stress preceding alterations in Abeta. These data have important implications for understanding how WD may potentially contribute to brain dysfunction and the development of neurodegenerative disorders such as Alzheimer's disease.

  20. AarF Domain Containing Kinase 3 (ADCK3 Mutant Cells Display Signs of Oxidative Stress, Defects in Mitochondrial Homeostasis and Lysosomal Accumulation.

    Directory of Open Access Journals (Sweden)

    Jason K Cullen

    Full Text Available Autosomal recessive ataxias are a clinically diverse group of syndromes that in some cases are caused by mutations in genes with roles in the DNA damage response, transcriptional regulation or mitochondrial function. One of these ataxias, known as Autosomal Recessive Cerebellar Ataxia Type-2 (ARCA-2, also known as SCAR9/COQ10D4; OMIM: #612016, arises due to mutations in the ADCK3 gene. The product of this gene (ADCK3 is an atypical kinase that is thought to play a regulatory role in coenzyme Q10 (CoQ10 biosynthesis. Although much work has been performed on the S. cerevisiae orthologue of ADCK3, the cellular and biochemical role of its mammalian counterpart, and why mutations in this gene lead to human disease is poorly understood. Here, we demonstrate that ADCK3 localises to mitochondrial cristae and is targeted to this organelle via the presence of an N-terminal localisation signal. Consistent with a role in CoQ10 biosynthesis, ADCK3 deficiency decreased cellular CoQ10 content. In addition, endogenous ADCK3 was found to associate in vitro with recombinant Coq3, Coq5, Coq7 and Coq9, components of the CoQ10 biosynthetic machinery. Furthermore, cell lines derived from ARCA-2 patients display signs of oxidative stress, defects in mitochondrial homeostasis and increases in lysosomal content. Together, these data shed light on the possible molecular role of ADCK3 and provide insight into the cellular pathways affected in ARCA-2 patients.

  1. Physical exercise prevents short and long-term deficits on aversive and recognition memory and attenuates brain oxidative damage induced by maternal deprivation.

    Science.gov (United States)

    Neves, Ben-Hur; Menezes, Jefferson; Souza, Mauren Assis; Mello-Carpes, Pâmela B

    2015-12-01

    It is known from previous research that physical exercise prevents long-term memory deficits induced by maternal deprivation in rats. But we could not assume similar effects of physical exercise on short-term memory, as short- and long-term memories are known to result from some different memory consolidation processes. Here we demonstrated that, in addition to long-term memory deficit, the short-term memory deficit resultant from maternal deprivation in object recognition and aversive memory tasks is also prevented by physical exercise. Additionally, one of the mechanisms by which the physical exercise influences the memory processes involves its effects attenuating the oxidative damage in the maternal deprived rats' hippocampus and prefrontal cortex.

  2. 2-ethylhydracrylic aciduria in short/branched-chain acyl-CoA dehydrogenase deficiency

    DEFF Research Database (Denmark)

    Korman, Stanley H; Andresen, Brage S; Zeharia, Avraham

    2005-01-01

    BACKGROUND: Isolated excretion of 2-methylbutyrylglycine (2-MBG) is the hallmark of short/branched-chain acyl-CoA dehydrogenase deficiency (SBCADD), a recently identified defect in the proximal pathway of L-isoleucine oxidation. SBCADD might be underdiagnosed because detection and recognition...

  3. Growth of epitaxially oriented Ag nanoislands on air-oxidized Si(1 1 1)-(7 × 7) surfaces: Influence of short-range order on the substrate

    International Nuclear Information System (INIS)

    Roy, Anupam; Bhattacharjee, K.; Ghatak, J.; Dev, B.N.

    2012-01-01

    Clean Si(1 1 1)-(7 × 7) surfaces, followed by air-exposure, have been investigated by reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). Fourier transforms (FTs) of STM images show the presence of short-range (7 × 7) order on the air-oxidized surface. Comparison with FTs of STM images from a clean Si(1 1 1)-(7 × 7) surface shows that only the 1/7th order spots are present on the air-oxidized surface. The oxide layer is ∼2-3 nm thick, as revealed by cross-sectional transmission electron microscopy (XTEM). Growth of Ag islands on these air-oxidized Si(1 1 1)-(7 × 7) surfaces has been investigated by in situ RHEED and STM and ex situ XTEM and scanning electron microscopy. Ag deposition at room temperature leads to the growth of randomly oriented Ag islands while preferred orientation evolves when Ag is deposited at higher substrate temperatures. For deposition at 550 °C face centered cubic Ag nanoislands grow with a predominant epitaxial orientation [11 ¯ 0] Ag ||[11 ¯ 0] Si , (1 1 1) Ag || (1 1 1) Si along with its twin [1 ¯ 10] Ag ||[11 ¯ 0] Si , (1 1 1) Ag || (1 1 1) Si , as observed for epitaxial growth of Ag on Si(1 1 1) surfaces. The twins are thus rotated by a 180° rotation of the Ag unit cell about the Si[1 1 1] axis. It is intriguing that Ag nanoislands follow an epitaxial relationship with the Si(1 1 1) substrate in spite of the presence of a 2-3 nm thick oxide layer between Ag and Si. Apparently the short-range order on the oxide surface influences the crystallographic orientation of the Ag nanoislands.

  4. A short-term supranutritional vitamin E supplementation alleviated respiratory alkalosis but did not reduce oxidative stress in heat stressed pigs

    Directory of Open Access Journals (Sweden)

    Fan Liu

    2018-02-01

    Full Text Available Objective Heat stress (HS triggers oxidative stress and respiratory alkalosis in pigs. The objective of this experiment was to study whether a short-term supranutritional amount of dietary vitamin E (VE can mitigate oxidative stress and respiratory alkalosis in heat-stressed pigs. Methods A total of 24 pigs were given either a control diet (17 IU/kg VE or a high VE (200 IU/kg VE; HiVE diet for 14 d, then exposed to thermoneutral (TN; 20°C, 45% humidity or HS (35°C, 35% to 45% humidity, 8 h daily conditions for 7 d. Respiration rate and rectal temperature were measured three times daily during the thermal exposure. Blood gas variables and oxidative stress markers were studied in blood samples collected on d 7. Results Although HiVE diet did not affect the elevated rectal temperature or respiration rate observed during HS, it alleviated (all p<0.05 for diet×temperature the loss of blood CO2 partial pressure and bicarbonate, as well as the increase in blood pH in the heat-stressed pigs. The HS reduced (p = 0.003 plasma biological antioxidant potential (BAP and tended to increase (p = 0.067 advanced oxidized protein products (AOPP in the heat-stressed pigs, suggesting HS triggers oxidative stress. The HiVE diet did not affect plasma BAP or AOPP. Only under TN conditions the HiVE diet reduced the plasma reactive oxygen metabolites (p<0.05 for diet× temperature. Conclusion A short-term supplementation with 200 IU/kg VE partially alleviated respiratory alkalosis but did not reduce oxidative stress in heat-stressed pigs.

  5. Scan direction induced charging dynamics and the application for detection of gate to S/D shorts in logic devices

    Science.gov (United States)

    Lei, Ming; Tian, Qing; Wu, Kevin; Zhao, Yan

    2016-03-01

    Gate to source/drain (S/D) short is the most common and detrimental failure mechanism for advanced process technology development in Metal-Oxide-Semiconductor-Field-Effect-Transistor (MOSFET) device manufacturing. Especially for sub-1Xnm nodes, MOSFET device is more vulnerable to gate-S/D shorts due to the aggressive scaling. The detection of this kind of electrical short defect is always challenging for in-line electron beam inspection (EBI), especially new shorting mechanisms on atomic scale due to new material/process flow implementation. The second challenge comes from the characterization of the shorts including identification of the exact shorting location. In this paper, we demonstrate unique scan direction induced charging dynamics (SDCD) phenomenon which stems from the transistor level response from EBI scan at post metal contact chemical-mechanical planarization (CMP) layers. We found that SDCD effect is exceptionally useful for gate-S/D short induced voltage contrast (VC) defect detection, especially for identification of shorting locations. The unique SDCD effect signatures of gate-S/D shorts can be used as fingerprint for ground true shorting defect detection. Correlation with other characterization methods on the same defective location from EBI scan shows consistent results from various shorting mechanism. A practical work flow to implement the application of SDCD effect for in-line EBI monitor of critical gate-S/D short defects is also proposed, together with examples of successful application use cases which mostly focus on static random-access memory (SRAM) array regions. Although the capability of gate-S/D short detection as well as expected device response is limited to passing transistors and pull-down transistors due to the design restriction from standard 6-cell SRAM structure, SDCD effect is proven to be very effective for gate-S/D short induced VC defect detection as well as yield learning for advanced technology development.

  6. Defects and defect processes in nonmetallic solids

    CERN Document Server

    Hayes, W

    2004-01-01

    This extensive survey covers defects in nonmetals, emphasizing point defects and point-defect processes. It encompasses electronic, vibrational, and optical properties of defective solids, plus dislocations and grain boundaries. 1985 edition.

  7. Temporal patterning of the potential induced by localized corrosion of iron passivity in acid media. Growth and breakdown of the oxide film described in terms of a point defect model.

    Science.gov (United States)

    Sazou, Dimitra; Pavlidou, Maria; Pagitsas, Michael

    2009-10-21

    This work analyses the nature of temporal patterning of the anodic potential induced by chlorides during polarization of iron under current-controlled conditions in acid solutions. It is shown that potential oscillations emerged as a result of the local chloride attack of a thin oxide layer, which covers the iron surface in its passive state. The mechanism by which both the local oxide breakdown and the subsequent localized active dissolution (pitting) occur is explained by considering a point defect model (PDM) developed to describe the oxide growth and breakdown. According to the PDM, chlorides occupy oxygen vacancies resulting in the inhibition of oxide growth and autocatalytic generation of cation vacancies that destabilize the oxide layer. Simultaneous transformation of the outer surface of the inner oxide layer to non-adherent ferrous chloride or oxo-chloride species leads to a further thinning of the oxide layer and its lifting-on from the iron surface. The process repeats again yielding sustained oscillations of the anodic potential. Analysis of the oscillatory response obtained under current-controlled conditions as a function of either the current or the time allows the suggestion of a set of alternate diagnostic criteria, which might be used to characterize localized corrosion of iron in acid solutions.

  8. The oxidative debt of fasting: evidence for short- to medium-term costs of advanced fasting in adult king penguins.

    Science.gov (United States)

    Schull, Quentin; Viblanc, Vincent A; Stier, Antoine; Saadaoui, Hédi; Lefol, Emilie; Criscuolo, François; Bize, Pierre; Robin, Jean-Patrice

    2016-10-15

    In response to prolonged periods of fasting, animals have evolved metabolic adaptations helping to mobilize body reserves and/or reduce metabolic rate to ensure a longer usage of reserves. However, those metabolic changes can be associated with higher exposure to oxidative stress, raising the question of how species that naturally fast during their life cycle avoid an accumulation of oxidative damage over time. King penguins repeatedly cope with fasting periods of up to several weeks. Here, we investigated how adult male penguins deal with oxidative stress after an experimentally induced moderate fasting period (PII) or an advanced fasting period (PIII). After fasting in captivity, birds were released to forage at sea. We measured plasmatic oxidative stress on the same individuals at the start and end of the fasting period and when they returned from foraging at sea. We found an increase in activity of the antioxidant enzyme superoxide dismutase along with fasting. However, PIII individuals showed higher oxidative damage at the end of the fast compared with PII individuals. When they returned from re-feeding at sea, all birds had recovered their initial body mass and exhibited low levels of oxidative damage. Notably, levels of oxidative damage after the foraging trip were correlated to the rate of mass gain at sea in PIII individuals but not in PII individuals. Altogether, our results suggest that fasting induces a transitory exposure to oxidative stress and that effort to recover in body mass after an advanced fasting period may be a neglected carryover cost of fasting. © 2016. Published by The Company of Biologists Ltd.

  9. Oxidative stress response in SH-SY5Y cells exposed to short-term 1800 MHz radiofrequency radiation.

    Science.gov (United States)

    Marjanovic Cermak, Ana Marija; Pavicic, Ivan; Trosic, Ivancica

    2018-01-28

    The exact mechanism that could explain the effects of radiofrequency (RF) radiation exposure at non-thermal level is still unknown. Increasing evidence suggests a possible involvement of reactive oxygen species (ROS) and development of oxidative stress. To test the proposed hypothesis, human neuroblastoma cells (SH-SY5Y) were exposed to 1800 MHz short-term RF exposure for 10, 30 and 60 minutes. Electric field strength within Gigahertz Transverse Electromagnetic cell (GTEM) was 30 V m -1 and specific absorption rate (SAR) was calculated to be 1.6 W kg -1 . Cellular viability was measured by MTT assay and level of ROS was determined by fluorescent probe 2',7'-dichlorofluorescin diacetate. Concentrations of malondialdehyde and protein carbonyls were used to assess lipid and protein oxidative damage and antioxidant activity was evaluated by measuring concentrations of total glutathione (GSH). After radiation exposure, viability of irradiated cells remained within normal physiological values. Significantly higher ROS level was observed for every radiation exposure time. After 60 min of exposure, the applied radiation caused significant lipid and protein damage. The highest GSH concentration was detected after 10 minute-exposure. The results of our study showed enhanced susceptibility of SH-SY5Y cells for development of oxidative stress even after short-term RF exposure.

  10. Vulnerability to oxidative stress in vitro in pathophysiology of mitochondrial short-chain acyl-CoA dehydrogenase deficiency: response to antioxidants.

    Directory of Open Access Journals (Sweden)

    Zarazuela Zolkipli

    Full Text Available OBJECTIVE: To elucidate the pathophysiology of SCAD deficient patients who have a unique neurological phenotype, among fatty acid oxidation disorders, with early developmental delay, CNS malformations, intractable seizures, myopathy and clinical signs suggesting oxidative stress. METHODS: We studied skin fibroblast cultures from patients homozygous for ACADS common variant c.625G>A (n = 10, compound heterozygous for c.625G>A/c.319C>T (n = 3 or homozygous for pathogenic c.319C>T (n = 2 and c.1138C>T (n = 2 mutations compared to fibroblasts from patients with carnitine palmitoyltransferase 2 (CPT2 (n = 5, mitochondrial trifunctional protein (MTP/long-chain L-3-hydroxyacyl-CoA dehydrogenase (LCHAD (n = 7, and medium-chain acyl-CoA dehydrogenase (MCAD deficiencies (n = 4 and normal controls (n = 9. All were exposed to 50 µM menadione at 37°C. Additional conditions included exposure to 39°C and/or hypoglycemia. Time to 100% cell death was confirmed with trypan blue dye exclusion. Experiments were repeated with antioxidants (Vitamins C and E or N-acetylcysteine, Bezafibrate or glucose and temperature rescue. RESULTS: The most significant risk factor for vulnerability to menadione-induced oxidative stress was the presence of a FAO defect. SCADD fibroblasts were the most vulnerable compared to other FAO disorders and controls, and were similarly affected, independent of genotype. Cell death was exacerbated by hyperthermia and/or hypoglycemia. Hyperthermia was a more significant independent risk factor than hypoglycemia. Rescue significantly prolonged survival. Incubation with antioxidants and Bezafibrate significantly increased viability of SCADD fibroblasts. INTERPRETATION: Vulnerability to oxidative stress likely contributes to neurotoxicity of SCADD regardless of ACADS genotype and is significantly exacerbated by hyperthermia. We recommend rigorous temperature control in SCADD patients during acute illness

  11. Bi-component semiconductor oxide photoanodes for the photoelectrocatalytic oxidation of organic solutes and vapours: a short review with emphasis to TiO2-WO3 photoanodes.

    Science.gov (United States)

    Georgieva, J; Valova, E; Armyanov, S; Philippidis, N; Poulios, I; Sotiropoulos, S

    2012-04-15

    The use of binary semiconductor oxide anodes for the photoelectrocatalytic oxidation of organic species (both in solution and gas phase) is reviewed. In the first part of the review, the principle of electrically assisted photocatalysis is presented, the preparation methods for the most common semiconductor oxide catalysts are briefly mentioned, while the advantages of appropriately chosen semiconductor combinations for efficient UV and visible (vis) light utilization are highlighted. The second part of the review focuses on the discussion of TiO(2)-WO(3) photoanodes (among the most studied bi-component semiconductor oxide systems) and in particular on coatings prepared by electrodeposition/electrosynthesis or powder mixtures (the focus of the authors' research during recent years). Studies concerning the microscopic, spectroscopic and photoelectrochemical characterization of the catalysts are presented and examples of photoanode activity towards typical dissolved organic contaminants as well as organic vapours are given. Particular emphasis is paid to: (a) The dependence of photoactivity on catalyst morphology and composition and (b) the possibility of carrying out photoelectrochemistry in all-solid cells, thus opening up the opportunity for photoelectrocatalytic air treatment. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Structured medium and long chain triglycerides show short-term increases in fat oxidation, but no changes in adiposity in men.

    Science.gov (United States)

    Roynette, Catherine E; Rudkowska, Iwona; Nakhasi, Dilip K; Jones, Peter J H

    2008-05-01

    Medium chain triglycerides (MCT) have been suggested as modulators of human energy expenditure (EE) and thus may influence total and regional body fat distribution. To investigate in overweight men the effects of structured medium and long chain triglycerides on EE, substrate oxidation and body adiposity, compared to extra virgin olive oil (OO). In a 6 week single-blind crossover study, 23 overweight men were randomly assigned to consume a standard high-fat diet of which 75% total fat was provided as either structured medium and long chain triglycerides referred to as structured oil (StO), or OO. EE and body composition were measured using indirect calorimetry and magnetic resonance imaging, respectively, at weeks 1 and 6 of each phase. Body weight decreased (pstructured medium and long chain triglyceride oil increases short-term fat oxidation but fails to modulate body weight or adiposity through a change in EE.

  13. A short-term supranutritional vitamin E supplementation alleviated respiratory alkalosis but did not reduce oxidative stress in heat stressed pigs.

    Science.gov (United States)

    Liu, Fan; Celi, Pietro; Chauhan, Surinder Singh; Cottrell, Jeremy James; Leury, Brian Joseph; Dunshea, Frank Rowland

    2018-02-01

    Heat stress (HS) triggers oxidative stress and respiratory alkalosis in pigs. The objective of this experiment was to study whether a short-term supranutritional amount of dietary vitamin E (VE) can mitigate oxidative stress and respiratory alkalosis in heat-stressed pigs. A total of 24 pigs were given either a control diet (17 IU/kg VE) or a high VE (200 IU/kg VE; HiVE) diet for 14 d, then exposed to thermoneutral (TN; 20°C, 45% humidity) or HS (35°C, 35% to 45% humidity, 8 h daily) conditions for 7 d. Respiration rate and rectal temperature were measured three times daily during the thermal exposure. Blood gas variables and oxidative stress markers were studied in blood samples collected on d 7. Although HiVE diet did not affect the elevated rectal temperature or respiration rate observed during HS, it alleviated (all prespiratory alkalosis but did not reduce oxidative stress in heat-stressed pigs.

  14. Defect-rich Ni-Ti layered double hydroxide as a highly efficient support for Au nanoparticles in base-free and solvent-free selective oxidation of benzyl alcohol.

    Science.gov (United States)

    Liu, Mengran; Fan, Guoli; Yu, Jiaying; Yang, Lan; Li, Feng

    2018-04-17

    Tuning the surface properties of supported metal catalysts is of vital importance for governing their catalytic performances in nanocatalysis. Here, we report highly dispersed nanometric gold nanoparticles (NPs) supported on Ni-Ti layered double hydroxides (NiTi-LDHs), which were employed in solvent-free and base-free selective oxidation of benzyl alcohol. A series of characterization techniques demonstrated that defect-rich NiTi-LDHs could efficiently stabilize Au NPs and decrease surface electron density of Au NPs. The as-formed Au/NiTi-LDH catalyst with a Ni/Ti molar ratio of 3 : 1 and an Au loading of 0.71 wt% yielded the highest turnover frequency value of ∼4981 h-1 at 120 °C among tested Au/NiTi-LDH catalysts with different Ni/Ti molar ratios, along with a high benzaldehyde selectivity of 98%. High catalytic efficiency of the catalyst was mainly correlated with surface cooperation between unique defects (i.e. defective Ti3+ species and oxygen vacancies) and abundant hydroxyl groups on the brucite-like layers of the NiTi-LDH support, which could lead to the preferential adsorption and activation of an alcohol hydroxyl moiety in benzyl alcohol and oxygen molecule, as well as the formation of more electron-deficient Ni3+ and Au0 species on the catalyst surface. Furthermore, the present Au/NiTi-LDH catalyst tolerated the oxidation of a wide variety of substrate structures into the corresponding aldehydes, acids or ketones. Our primary results illustrate that defect-rich NiTi-LDHs are promising supports which can efficiently modify surface structure and electronic properties of supported metal catalysts and consequently improve their catalytic performances.

  15. Photochemical oxidation of short-chain polychlorinated n-alkane mixtures using H2O2/UV and the photo-Fenton reaction

    OpenAIRE

    Ken J. Friesen; Taha M. El-Morsi; Alaa S. Abd-El-Aziz

    2004-01-01

    The photochemical oxidation of a series of short-chain polychlorinated n-alkane (PCA) mixtures was investigated using H2O2/UV and modified photo-Fenton conditions (Fe3+/H2O2/UV) in both Milli-Q and lake water. All PCA mixtures, including chlorinated (Cl5 to Cl8) decanes, undecanes, dodecanes and tridecanes degraded in 0.02 M H2O2/UV at pH 2.8 in pure water, with 80±4% disappearance after 3 h of irradiation using a 300 nm light source. Degradation was somewhat enhanced under similar conditions...

  16. Short-term nitrous oxide profile dynamics and emissions response to water, nitrogen and carbon additions in two tropical soils

    Science.gov (United States)

    A. D. Nobre; M. Keller; P. M. Crill; R. C. Harriss

    2001-01-01

    Tropical soils are potentially the highest and least studied nitrous oxide (N2O) production areas in the world. The effect of water, nitrate and glucose additions on profile concentrations and episodic emissions of N2O for two volcanic soils in Costa Rica was examined. Magnitudes of episodic N2O pulses, as well as overall N2O emissions, varied considerably and...

  17. Short exposure to acetylene to distinguish between nitrifier and denitrifier nitrous oxide production in soil and sediment samples

    NARCIS (Netherlands)

    Kester, R.A.; Boer, W. de; Laanbroek, H.J.

    1996-01-01

    The contribution of nitrifiers and denitrifiers to the nitrous oxide production in slurries of calcareous silt loam and river bank sediment at different oxygen concentrations was determined using acetylene as nitrification inhibitor. The addition of 10 Pa acetylene resulted in inhibition of

  18. Short exposure to acetylene to distinguish between nitrifier and denitrifier nitrous oxide production in soil and sediment samples

    NARCIS (Netherlands)

    Kester, R.A.; De Boer, W.; Laanbroek, H.J.

    1996-01-01

    The contribution of nitrifiers and denitrifiers to the nitrous oxide production in slurries of calcareous silt loam and river bank sediment at different oxygen concentrations was determined using acetylene as nitrification inhibitor. The addition of 10 Pa acetylene resulted in inhibition of nitrous

  19. Charged Semiconductor Defects Structure, Thermodynamics and Diffusion

    CERN Document Server

    Seebauer, Edmund G

    2009-01-01

    The technologically useful properties of a solid often depend upon the types and concentrations of the defects it contains. Not surprisingly, defects in semiconductors have been studied for many years, in many cases with a view towards controlling their behavior through various forms of "defect engineering." For example, in the bulk, charging significantly affects the total concentration of defects that are available to mediate phenomena such as solid-state diffusion. Surface defects play an important role in mediating surface mass transport during high temperature processing steps such as epitaxial film deposition, diffusional smoothing in reflow, and nanostructure formation in memory device fabrication. Charged Semiconductor Defects details the current state of knowledge regarding the properties of the ionized defects that can affect the behavior of advanced transistors, photo-active devices, catalysts, and sensors. Features: Group IV, III-V, and oxide semiconductors; Intrinsic and extrinsic defects; and, P...

  20. On an aspect of kinetics both defects accumulation and gas absorption in an irradiated metals oxides; K voprosu o kinetike nakopleniya defektov i adsorbtsii gazov v obluchennykh oksidakh metallov

    Energy Technology Data Exchange (ETDEWEB)

    Tuseev, T [Mekhdunarodnyj Kazakhsko-Turetskij Univ. im. Kh.A. Yasavi, Turkestan (Kazakhstan); Polyakov, A I; Bitenbaev, M I [Fiziko-Tekhnicheskij Inst., Almaty (Kazakhstan)

    2001-07-01

    In the work an analysis of experimental data during study both gases adsorption processes and radiation defects accumulation in irradiated (ultraviolet, gamma-, neutron-, alpha-particle- and proton radiation) in the oxides (SiO{sub 2}, Al{sub 2}O{sub 3}, BeO, Se{sub 2}O{sub 3}, Dy{sub 2}O{sub 3}, La{sub 2}O{sub 3}, Er{sub 2}O{sub 3}) is carried out. It is determined, that these processes are correlating with each other and equivalent kinetic equations for its description are proposed.

  1. Short communication: Characterizing metabolic and oxidant status of pastured dairy cows postpartum in an automatic milking system.

    Science.gov (United States)

    Elischer, M F; Sordillo, L M; Siegford, J M; Karcher, E L

    2015-10-01

    The periparturient period represents a stressful time for dairy cows as they transition from late gestation to early lactation. Undesirable fluctuations in metabolites and impaired immune defense mechanisms near parturition can severely affect cow health and have residual effects on performance and longevity. Metabolic and oxidative stress profiles of multiparous and primiparous dairy cows in traditional parlor and feeding systems are well characterized, but status of these profiles in alternative management systems, such as grazing cows managed with an automatic milking system (AMS), are poorly characterized. Therefore, the objective of this case study was to characterize the metabolic and oxidant status of pastured cows milked with an AMS. It was hypothesized that primiparous and multiparous cows milked with an AMS would experience changes in oxidative and metabolic status after parturition; however, these changes would not impair cow health or production. Blood was collected from 14 multiparous and 8 primiparous Friesian-cross dairy cows at 1, 7, 14, and 21 d relative to calving for concentrations of insulin, glucose, nonesterified fatty acids (NEFA), β-hydroxybutyrate, reduced glutathione, oxidized glutathione, and antioxidant potential. Milk production and milking frequency data were collected postpartum. Milk production differed on d 7 and 14 between primiparous and multiparous cows and frequency was not affected by parity. Primiparous cows had higher levels of glucose than multiparous cows. No differences in insulin, NEFA, or β-hydroxybutyrate concentrations were noted between multiparous and primiparous cows postpartum, though days relative to calving significantly affected insulin and NEFA. Primiparous cows also had higher antioxidant potential than multiparous cows during the postpartum period. Results from this study show that, although responses were within expected ranges, periparturient multiparous cows responded differently than periparturient

  2. Embedded defects

    International Nuclear Information System (INIS)

    Barriola, M.; Vachaspati, T.; Bucher, M.

    1994-01-01

    We give a prescription for embedding classical solutions and, in particular, topological defects in field theories which are invariant under symmetry groups that are not necessarily simple. After providing examples of embedded defects in field theories based on simple groups, we consider the electroweak model and show that it contains the Z string and a one-parameter family of strings called the W(α) string. It is argued that although the members of this family are gauge equivalent when considered in isolation, each member becomes physically distinct when multistring configurations are considered. We then turn to the issue of stability of embedded defects and demonstrate the instability of a large class of such solutions in the absence of bound states or condensates. The Z string is shown to be unstable for all values of the Higgs boson mass when θ W =π/4. W strings are also shown to be unstable for a large range of parameters. Embedded monopoles suffer from the Brandt-Neri-Coleman instability. Finally, we connect the electroweak string solutions to the sphaleron

  3. Effects of long- and short-term darbepoetin-α treatment on oxidative stress, inflammation and endothelial injury in ApoE knockout mice.

    Science.gov (United States)

    Özdemir, Evrim Dursun; Hanikoglu, Aysegul; Cort, Aysegul; Ozben, Beste; Suleymanlar, Gultekin; Ozben, Tomris

    2017-07-01

    Atherosclerosis and atherosclerosis-related complications are the main cause of death in the world. Vascular injury in response to inflammation and enhanced oxidant stress promotes endothelial dysfunction and leads to atherosclerotic lesions. Low-dose treatment with darbepoetin-α may be a potential therapeutic tool for endothelial injury and atherosclerosis. In order to study the effect of darbepoetin-α on endothelial injury and atherosclerosis, we used ApoE-/- mice as the atherosclerotic mice model. We monitored atherosclerosis and plaque formation histochemically in ApoE knockout mice at early and late stages of atherosclerosis. Darbepoetin-α was injected intraperitoneally at a dose of 0.1 μg/kg to ApoE-/- mice. The results of 2 ApoE-/- mice groups injected with darbepoetin-α (early and late stages of atherosclerosis) were compared to the results of the corresponding saline injected ApoE-/- mice groups and the control (C57BL/6) mice. Lipid profile (total cholesterol, triglyceride), inflammation (CRP, IL-6, histamine), endothelial injury (ICAM-1, selectin) and oxidative stress markers (lipid peroxidation, protein oxidation) were significantly increased in 4 atherosclerotic groups compared to the control group. Short-term darbepoetin-α had no marked effects on indicators of inflammation and endothelial injury in the ApoE knockout mice groups compared to the ApoE knockout mice not treated with darbepoetin-α, however, darbepoetin-α significantly decreased 8-isoprostane and protein carbonyl content. Long term darbepoetin-α treatment reduced oxidative stress in ApoE-/- mice. This study contributes to understanding and elucidating the biochemical changes occurring during early and late stages of atherosclerosis development regarding lipid profile, inflammation, endothelial injury and oxidative stress markers.

  4. Antimicrobial photodynamic therapy with photosensitizer in ethanol improves oxidative status and gingival collagen in a short-term in periodontitis.

    Science.gov (United States)

    Pillusky, Fernanda Maia; Barcelos, Raquel Cristine Silva; Vey, Luciana Taschetto; Barin, Luisa Machado; de Mello Palma, Victor; Maciel, Roberto Marinho; Kantorski, Karla Zanini; Bürger, Marilise Escobar; Danesi, Cristiane Cademartori

    2017-09-01

    This study evaluated the antimicrobial photodynamic therapy (aPDT) effects using the methylene blue (MB) in ethanol 20% on systemic oxidative status and collagen content from gingiva of rats with periodontitis. Rats were divided into five experimental groups: NC (negative control; no periodontitis); PC (positive control; periodontitis without any treatment); SRP (periodontitis and scaling and root planing), aPDT I (periodontitis and SRP+aPDT+MB solubilized in water), and aPDT II (periodontitis and SRP+aPDT+MB solubilized in ethanol 20%). After 7days of removal of the ligature, the periodontal treatments were performed. At 7/15/30days, gingival tissue was removed for morphometric analysis. The erythrocytes were used to evaluate systemic oxidative status. PC group showed higher lipoperoxidation levels at 7/15/30days. aPDT indicated a protective influence in erythrocytes at 15days observed by the elevation in levels of systemic antioxidant defense. aPDT II group was the only one that restored the total collagen area in 15days, and recovered the type I collagen area at the same time point. aPDT as an adjunct to the SRP can induce the systemic protective response against oxidative stress periodontitis-induced and recover the gingival collagen, thus promoting the healing periodontal, particularly when the MB is dissolved in ethanol 20%. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Sperm quality and oxidative status as affected by homogenization of liquid-stored boar semen diluted in short- and long-term extenders.

    Science.gov (United States)

    Menegat, Mariana B; Mellagi, Ana Paula G; Bortolin, Rafael C; Menezes, Tila A; Vargas, Amanda R; Bernardi, Mari Lourdes; Wentz, Ivo; Gelain, Daniel P; Moreira, José Cláudio F; Bortolozzo, Fernando P

    2017-04-01

    Homogenization of diluted boar semen during storage has for a long time been regarded as beneficial. Recent studies indicated an adverse effect of homogenization on sperm quality for yet unknown reasons. This study aimed to verify the effect of homogenization on sperm parameters and to elucidate the impact of oxidative stress. Twenty-one normospermic ejaculates (21 boars) were diluted with Androstar ® Plus (AND) and Beltsville Thawing Solution (BTS). Semen doses were submitted to no-homogenization (NoHom) or twice-a-day manual homogenization (2xHom) during storage at 17°C for 168h. NoHom and 2xHom were similar (P>0.05) for both short- and long-term extenders with respect to motility and kinematics parameters (CASA system), membrane viability (SYBR-14/PI), acrosome integrity, lipid peroxidation, protein oxidation, intracellular reactive oxygen species, sulfhydryl content, and total radical-trapping antioxidant potential. 2xHom reduced sperm motility and motion kinematics (VCL, VSL, VAP, BCF, and ALH) following the thermoresistance test and presented with a slight increase in pH along the storage (P=0.05) as compared to NoHom. Furthermore, 2xHom semen doses presented with a constant SOD and GSH-Px activity during storage whereas enzymatic activity increased for NoHom at the end of the storage. These findings confirm that homogenization of semen doses is detrimental to sperm quality. Moreover, it is shown that the effect of homogenization is unlikely to be primarily related to oxidative stress. Homogenization is not recommended for storage of liquid boar semen for up to 168h in both short- and long-term extenders. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Radiation-Induced Short Channel (RISCE) and Narrow Channel (RINCE) Effects in 65 and 130 nm MOSFETs

    CERN Document Server

    Faccio, F; Cornale, D; Paccagnella, A; Gerardin, S

    2015-01-01

    The behavior of transistors in commercial-grade complementary metal-oxide semiconductor technologies in the 65 and 130 nm nodes has been explored up to a total ionizing dose of 1 Grad. The large dose tolerance of the thin gate oxide is confirmed, but defects in the spacer and STI oxides have a strong effect on the performance of the transistors. A radiation-induced short channel effect is traced to charge trapping in the spacers used for drain engineering, while a radiation-induced narrow channel effect is due to defect generation in the lateral isolation oxide (STI). These strongly degrade the electrical characteristics of short and narrow channel transistors at high doses, and their magnitude depends on the applied bias and temperature during irradiation in a complex way.

  7. Short-Term Nose-Only Water-Pipe (Shisha Smoking Exposure Accelerates Coagulation and Causes Cardiac Inflammation and Oxidative Stress in Mice

    Directory of Open Access Journals (Sweden)

    Abderrahim Nemmar

    2015-01-01

    Full Text Available Background/Aim: Water-pipe smoking (WPS has acquired worldwide popularity, and is disseminating particularly rapidly in Europe and North America. However, little is known about the short-term cardiovascular effects of WPS. Methods: Presently, we assessed the short-term cardiovascular effects of nose-only exposure to mainstream WPS in BALB/c mice for 30 min/day for 5 consecutive days. Control mice were exposed to air. At the end of the exposure period, several cardiovascular endpoints were measured. Results: WPS did not affect the number of leukocytes and the plasma concentrations of C-reactive protein, tumor necrosis factor α (TNFα and interleukin-6 (IL-6. Likewise, plasma levels of lipid peroxidation (LPO, reduced glutathione (GSH and catalase were not affected by WPS. By contrast, WPS aggravated in vivo thrombosis by shortening the thrombotic occlusion time in pial arterioles and venules. The number of circulating platelets was reduced by WPS suggesting the occurrence of platelet aggregation in vivo. Elevated concentrations of fibrinogen and plasminogen activator inhibitor-1 were seen after the exposure to WPS. Blood samples taken from mice exposed to WPS and exposed to adenosine diphosphate showed more platelet aggregation. The heart concentrations of IL-6 and TNFα were augmented by WPS. Likewise, heart levels of LPO, reactive oxygen species and the antioxidants catalase and GSH were increased by WPS. However, the systolic blood pressure and heart rate were not affected by WPS. Conclusion: It can be concluded that short-term exposure to WPS exerts procoagulatory effects and induce cardiac inflammation and oxidative stress. At the time point investigated, there was no evidence for blood inflammation or oxidative stress.

  8. Short- and Long-Term Effects of Prenatal Exposure to Iron Oxide Nanoparticles: Influence of Surface Charge and Dose on Developmental and Reproductive Toxicity

    Directory of Open Access Journals (Sweden)

    Kristin R. Di Bona

    2015-12-01

    Full Text Available Iron oxide nanoparticles (NPs are commonly utilized for biomedical, industrial, and commercial applications due to their unique properties and potential biocompatibility. However, little is known about how exposure to iron oxide NPs may affect susceptible populations such as pregnant women and developing fetuses. To examine the influence of NP surface-charge and dose on the developmental toxicity of iron oxide NPs, Crl:CD1(ICR (CD-1 mice were exposed to a single, low (10 mg/kg or high (100 mg/kg dose of positively-charged polyethyleneimine-Fe2O3-NPs (PEI-NPs, or negatively-charged poly(acrylic acid-Fe2O3-NPs (PAA-NPs during critical windows of organogenesis (gestation day (GD 8, 9, or 10. A low dose of NPs, regardless of charge, did not induce toxicity. However, a high exposure led to charge-dependent fetal loss as well as morphological alterations of the uteri (both charges and testes (positive only of surviving offspring. Positively-charged PEI-NPs given later in organogenesis resulted in a combination of short-term fetal loss (42% and long-term alterations in reproduction, including increased fetal loss for second generation matings (mice exposed in utero. Alternatively, negatively-charged PAA-NPs induced fetal loss (22% earlier in organogenesis to a lesser degree than PEI-NPs with only mild alterations in offspring uterine histology observed in the long-term.

  9. Study on the drain bias effect on negative bias temperature instability degradation of an ultra-short p-channel metal-oxide-semiconductor field-effect transistor

    International Nuclear Information System (INIS)

    Yan-Rong, Cao; Xiao-Hua, Ma; Yue, Hao; Shi-Gang, Hu

    2010-01-01

    This paper studies the effect of drain bias on ultra-short p-channel metal-oxide-semiconductor field-effect transistor (PMOSFET) degradation during negative bias temperature (NBT) stress. When a relatively large gate voltage is applied, the degradation magnitude is much more than the drain voltage which is the same as the gate voltage supplied, and the time exponent gets larger than that of the NBT instability (NBTI). With decreasing drain voltage, the degradation magnitude and the time exponent all get smaller. At some values of the drain voltage, the degradation magnitude is even smaller than that of NBTI, and when the drain voltage gets small enough, the exhibition of degradation becomes very similar to the NBTI degradation. When a relatively large drain voltage is applied, with decreasing gate voltage, the degradation magnitude gets smaller. However, the time exponent becomes larger. With the help of electric field simulation, this paper concludes that the degradation magnitude is determined by the vertical electric field of the oxide, the amount of hot holes generated by the strong channel lateral electric field at the gate/drain overlap region, and the time exponent is mainly controlled by localized damage caused by the lateral electric field of the oxide in the gate/drain overlap region where hot carriers are produced. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  10. Simulation of synaptic short-term plasticity using Ba(CF3SO3)2-doped polyethylene oxide electrolyte film.

    Science.gov (United States)

    Chang, C T; Zeng, F; Li, X J; Dong, W S; Lu, S H; Gao, S; Pan, F

    2016-01-07

    The simulation of synaptic plasticity using new materials is critical in the study of brain-inspired computing. Devices composed of Ba(CF3SO3)2-doped polyethylene oxide (PEO) electrolyte film were fabricated and with pulse responses found to resemble the synaptic short-term plasticity (STP) of both short-term depression (STD) and short-term facilitation (STF) synapses. The values of the charge and discharge peaks of the pulse responses did not vary with input number when the pulse frequency was sufficiently low(~1 Hz). However, when the frequency was increased, the charge and discharge peaks decreased and increased, respectively, in gradual trends and approached stable values with respect to the input number. These stable values varied with the input frequency, which resulted in the depressed and potentiated weight modifications of the charge and discharge peaks, respectively. These electrical properties simulated the high and low band-pass filtering effects of STD and STF, respectively. The simulations were consistent with biological results and the corresponding biological parameters were successfully extracted. The study verified the feasibility of using organic electrolytes to mimic STP.

  11. Single ventricle cardiac defect

    International Nuclear Information System (INIS)

    Eren, B.; Turkmen, N.; Fedakar, R.; Cetin, V.

    2010-01-01

    Single ventricle heart is defined as a rare cardiac abnormality with a single ventricle chamber involving diverse functional and physiological defects. Our case is of a ten month-old baby boy who died shortly after admission to the hospital due to vomiting and diarrhoea. Autopsy findings revealed cyanosis of finger nails and ears. Internal examination revealed; large heart, weighing 60 grams, single ventricle, without a septum and upper membranous part. Single ventricle is a rare pathology, hence, this paper aims to discuss this case from a medico-legal point of view. (author)

  12. Cobalt-60 oxide aerosols: methods of production and short-term retention and distribution kinetics in the beagle dog

    International Nuclear Information System (INIS)

    Barnes, J.E.; Kanapilly, G.M.; Newton, G.J.

    1976-01-01

    Cobalt-60 has been used extensively in nuclear applications and has been considered for use in nuclear auxiliary power devices. The most common chemical form used is the oxide. This study of the retention and distribution of two differnt exoides of cobalt when administered by inhalation was conducted to assess the potential inhalation hazard associated with its use. Cobaltosic oxide (Co 3 O 4 ) was formed by passing a cobalt nitrate aerosol through a heating column at 850 0 C before delivery to the dog. Cobaltous oxide (CoO) was formed by raising the heating column temperature to 1400 0 C. Three beagle dogs were exposed to 60 Co 3 O 4 and sacrificed singly at 8, 64 and 128 days. Three beagle dogs were exposed to 60 CoO and sacrificed at 8, 16 and 64 days after exposure. Whole-body retention patterns showed that 60 CoO left the body with a shorter effective half-life than 60 Co 3 O 4 . The concentration of 60 Co detected in the blood was at least an order of magnitude higher in the dogs exposed to 60 CoO than in the dogs exposed to 60 Co 3 O 4 . Cobalt-60 translocated from the lung accumulated predominantly in the kidney, liver, skeleton and cartilagenous structures such as the trachea. Higher concentrations were reached earlier in the dogs exposed to 60 CoO. After early fecal excretion of material deposited in the upper respiratory tract, excretion was greatest via the urine. The higher solubility of the 60 CoO formed at 1400 0 C relative to 60 Co 3 O 4 formed at 850 0 C is noteworthy considering that generally aerosols formed at higher temperatures are more insoluble than aerosols formed at lower temperatures. (author)

  13. The effect of weight loss on serum concentrations of nitric oxide induced by short - term exercise in obese women

    Directory of Open Access Journals (Sweden)

    M Olszanecka-Glinianowicz

    2009-07-01

    Full Text Available Objective: The aim of present study was to examine the effect of weight loss comprising regular moderate physical activity on resting serum concentrations of nitric oxide metabolites and exercise induced NO release. Materials and Methods: The study was carried out in 43 obese women without additional diseases (age 41.8±11.9y, body weight 94.5±15.1kg, BMI 36.5±4.6kg/m2. All obese patients participated in a 3-month weight reduction programme that consisted of 1 a group instruction in behavioural and dietary methods of weight control every two weeks; 2 1000-1400kcal/day balanced diet, and 3 moderate physical exercises (30 minutes, 3 times a week. Before and after treatment body mass and height were measured, body mass index (BMI was calculated. Body composition was determined by impedance analysis using a Bodystat analyser. The serum concentration of nitric oxide metabolites before and after exercise was measured using spectrophotometry method by Griess. The serum concentrations of lactate before and after exercise were measured with the use of strip test (ACCUSPORT analyzer. Serum concentration of insulin was measured with the use of RIA. Plasma glucose, cholesterol, HDL cholesterol and triglicerydes were determined by enzymatic procedure. Results: The mean weight loss during treatment was 8.3±4.3 kg. We did not observe differences between resting serum concentrations of NO and lactate before and after weight loss. During exercise serum NO concentrations increased significantly both before and after weight loss treatment. After the weight reduction treatment, the time of exercise test increased significantly P<0.005, but there were no significant differences between the value of NO before and after weight loss. Conclusion: 3 – month regular physical activity and weight loss did not influence exercise-induced nitric oxide production.

  14. Fluxomic evidence for impaired contribution of short-chain acyl-CoA dehydrogenase to mitochondrial palmitate β-oxidation in symptomatic patients with ACADS gene susceptibility variants.

    Science.gov (United States)

    Dessein, Anne-Frédérique; Fontaine, Monique; Joncquel-Chevalier Curt, Marie; Briand, Gilbert; Sechter, Claire; Mention-Mulliez, Karine; Dobbelaere, Dries; Douillard, Claire; Lacour, Arnaud; Redonnet-Vernhet, Isabelle; Lamireau, Delphine; Barth, Magalie; Minot-Myhié, Marie-Christine; Kuster, Alice; de Lonlay, Pascale; Gregersen, Niels; Acquaviva, Cécile; Vianey-Saban, Christine; Vamecq, Joseph

    2017-08-01

    Despite ACADS (acyl-CoA dehydrogenase, short-chain) gene susceptibility variants (c.511C>T and c.625G>A) are considered to be non-pathogenic, encoded proteins are known to exhibit altered kinetics. Whether or not, they might affect overall fatty acid β-oxidation still remains, however, unclear. De novo biosynthesis of acylcarnitines by whole blood samples incubated with deuterated palmitate (16- 2 H 3 ,15- 2 H 2 -palmitate) is suitable as a fluxomic exploration to distinguish between normal and disrupted β-oxidation, abnormal profiles and ratios of acylcarnitines with different chain-lengths being indicative of the site for enzymatic blockade. Determinations in 301 control subjects of ratios between deuterated butyrylcarnitine and sum of deuterated C2 to C14 acylcarnitines served here as reference values to state specifically functional SCAD impairment in patients addressed for clinical and/or biological suspicion of a β-oxidation disorder. Functional SCAD impairment was found in 39 patients. The 27 patients accepting subsequent gene studies were all positive for ACADS mutations. Twenty-six of 27 patients were positive for c.625G>A variant. Twenty-three of 27 patients harbored susceptibility variants as sole ACADS alterations (18 homozygous and 3 heterozygous for c.625G>A, 2 compound heterozygous for c.625G>A/c.511C>T). Our present fluxomic assessment of SCAD suggests a link between ACADS susceptibility variants and abnormal β-oxidation consistent with known altered kinetics of these variants. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Short-term exercise worsens cardiac oxidative stress and fibrosis in 8-month-old db/db mice by depleting cardiac glutathione.

    Science.gov (United States)

    Laher, Ismail; Beam, Julianne; Botta, Amy; Barendregt, Rebekah; Sulistyoningrum, Dian; Devlin, Angela; Rheault, Mark; Ghosh, Sanjoy

    2013-01-01

    Moderate exercise improves cardiac antioxidant status in young humans and animals with Type-2 diabetes (T2D). Given that both diabetes and advancing age synergistically decrease antioxidant expression in most tissues, it is unclear whether exercise can upregulate cardiac antioxidants in chronic animal models of T2D. To this end, 8-month-old T2D and normoglycemic mice were exercised for 3 weeks, and cardiac redox status was evaluated. As expected, moderate exercise increased cardiac antioxidants and attenuated oxidative damage in normoglycemic mice. In contrast, similar exercise protocol in 8-month-old db/db mice worsened cardiac oxidative damage, which was associated with a specific dysregulation of glutathione (GSH) homeostasis. Expression of enzymes for GSH biosynthesis [γ-glutamylcysteine synthase, glutathione reductase] as well as for GSH-mediated detoxification (glutathione peroxidase, glutathione-S-transferase) was lower, while toxic metabolites dependent on GSH for clearance (4-hydroxynonenal) were increased in exercised diabetic mice hearts. To validate GSH loss as an important factor for such aggravated damage, daily administration of GSH restored cardiac GSH levels in exercised diabetic mice. Such supplementation attenuated both oxidative damage and fibrotic changes in the myocardium. Expression of transforming growth factor beta (TGF-β) and its regulated genes which are responsible for such profibrotic changes were also attenuated with GSH supplementation. These novel findings in a long-term T2D animal model demonstrate that short-term exercise by itself can deplete cardiac GSH and aggravate cardiac oxidative stress. As GSH administration conferred protection in 8-month-old diabetic mice undergoing exercise, supplementation with GSH-enhancing agents may be beneficial in elderly diabetic patients undergoing exercise.

  16. International conference on defects in insulating crystals

    International Nuclear Information System (INIS)

    1977-01-01

    Short summaries of conference papers are presented. Some of the conference topics included transport properties, defect levels, superionic conductors, radiation effects, John-Teller effect, electron-lattice interactions, and relaxed excited states

  17. International conference on defects in insulating crystals

    Energy Technology Data Exchange (ETDEWEB)

    1977-01-01

    Short summaries of conference papers are presented. Some of the conference topics included transport properties, defect levels, superionic conductors, radiation effects, John-Teller effect, electron-lattice interactions, and relaxed excited states. (SDF)

  18. A short review on the pulsed laser deposition of Er3+ ion doped oxide glass thin films for integrated optics

    International Nuclear Information System (INIS)

    Irannejad, M.; Zhao, Z.; Jose, G.; Steenson, D.P.; Jha, A.

    2010-01-01

    Short pulsed (ns) excimer laser was employed as a technique for the deposition of more than 2 μm thick glassy films from phosphorous pentoxide and tungsten lanthanum modified tellurite bulk glasses. High quality glass thin films with measured propagation loss less than 0.15, 0.71 and 2.3 dB.cm -1 were obtained after optimization of deposition parameters for silica, siloxane and semiconductor substrates. The optical, spectroscopic and microstructural properties of deposited thin films were compared with bulk glass materials for demonstrating the differences in the properties, which must be optimized for device engineering. Channel waveguides were fabricated after using reactive ion etching technique, up to 2 μm thickness by using CHF 3 and Ar gas mixture

  19. Structure of short-range-ordered iron(III)-precipitates formed by iron(II) oxidation in water containing phosphate, silicate, and calcium

    Science.gov (United States)

    Voegelin, A.; Frommer, J.; Vantelon, D.; Kaegi, R.; Hug, S. J.

    2009-04-01

    The oxidation of Fe(II) in water leads to the formation of Fe(III)-precipitates that strongly affect the fate of nutrients and contaminants in natural and engineered systems. Examples include the cycling of As in rice fields irrigated with As-rich groundwater or the treatment of drinking water for As removal. Knowledge of the types of Fe(III)-precipitates forming in such systems is essential for the quantitative modeling of nutrient and contaminant dynamics and for the optimization of water purification techniques on the basis of a mechanistic understanding of the relevant biogeochemical processes. In this study, we investigated the local coordination of Fe, P, and Ca in Fe(III)-precipitates formed by aeration of synthetic Fe(II)-containing groundwater with variable composition (pH 7, 2-30 mg/L Fe(II), 2-20 mg/L phosphate-P, 2-20 mg/L silicate-Si, 8 mM Na-bicarbonate or 2.5 mM Ca-&1.5 mM Mg-bicarbonate). After 4 hours of oxidation, Fe(III)-precipitates were collected on 0.2 µm nylon filters and dried. The precipitates were analyzed by Fe K-edge EXAFS (XAS beamline, ANKA, Germany) and by P and Ca K-edge XANES spectroscopy (LUCIA beamline, SLS, Switzerland). The Fe K-edge EXAFS spectra indicated that local Fe coordination in the precipitates systematically shifted with water composition. As long as water contained P, mainly short-range-ordered Fe(III)-phosphate formed (with molar P/Fe ~0.5). In the absence of P, Fe(III) precipitated as hydrous ferric oxide at high Si/Fe>0.5, as ferrihydrite at intermediate Si/Fe, and mainly as lepidocrocite at Si/Fe<0.2. Analysis of the EXAFS by shell-fitting indicated that Fe(III)-phosphates mainly contained mono- or oligomeric (edge- or corner-sharing) Fe and that the linkage between neighboring Fe(III)-octahedra changed from predominantly edge-sharing in Si-rich hydrous ferric oxide to edge- and corner-sharing in ferrihydrite. Electron microscopic data showed that changes in local precipitate structure were systematically

  20. Relative impact of short-term emissions controls on gas and particle-phase oxidative potential during the 2015 China Victory Day Parade in Beijing, China

    Science.gov (United States)

    Huang, Wei; Fang, Dongqing; Shang, Jing; Li, Zhengqiang; Zhang, Yang; Huo, Peng; Liu, Zhaoying; Schauer, James J.; Zhang, Yuanxun

    2018-06-01

    A field observation focusing on reactive oxygen species (ROS) was conducted before, during, and after the 2015 China Victory Day Parade to understand the influence of short-term emissions controls on atmospheric oxidative activity. The hourly average concentrations of PM2.5, SO2, NO, NO2, CO, O3, as well as gas and particle-phase ROS, were measured using a series of online instruments. PM2.5 concentrations during control days were significantly lower than non-control days, which directly lead to the "Parade Blue", yet reductions of most gaseous pollutants except SO2 were not so obvious as PM. Similarly, the control measures also led to a great loss of particle-phase ROS throughout the control period, while the reduction of ROS in gas phase was not obvious until the more stringent measures implemented since September 1. Furthermore, only weak positive correlations were observed among ROS and some other measured species, indicating ROS concentrations were affected by a number of comprehensive factors that single marker could not capture. Meanwhile, meteorological condition and regional transportation were also shown to be the minor factors affecting atmospheric oxidizing capacity. The results of this observation mainly revealed the control measures were conducive to reducing particle-related ROS. However, the reduction of gas-phase ROS activity was less effective given the menu of controls employed for the 2015 China Victory Day Parade. Therefore, short-term emissions controls only aimed to PM reduction and visibility improvement will produce the blue sky but will not equivalently reduce the gas-phase ROS. Supplemental control measures will be needed to further reduce gas-phase ROS concentrations.

  1. Response of Lemna minor L. to short-term cobalt exposure: The effect on photosynthetic electron transport chain and induction of oxidative damage

    Energy Technology Data Exchange (ETDEWEB)

    Begović, Lidija, E-mail: lbegovic@biologija.unios.hr [Josip Juraj Strossmayer University of Osijek, Department of Biology, Ulica cara Hadrijana 8/A, H R -31000 Osijek (Croatia); Mlinarić, Selma, E-mail: smlinaric@biologija.unios.hr [Josip Juraj Strossmayer University of Osijek, Department of Biology, Ulica cara Hadrijana 8/A, H R -31000 Osijek (Croatia); Antunović Dunić, Jasenka, E-mail: jantunovic@biologija.unios.hr [Josip Juraj Strossmayer University of Osijek, Department of Biology, Ulica cara Hadrijana 8/A, H R -31000 Osijek (Croatia); Katanić, Zorana, E-mail: zkatanic@biologija.unios.hr [Josip Juraj Strossmayer University of Osijek, Department of Biology, Ulica cara Hadrijana 8/A, H R -31000 Osijek (Croatia); Lončarić, Zdenko, E-mail: zdenko.loncaric@pfos.hr [Faculty of Agriculture, Josip Juraj Strossmayer University of Osijek, Ulica kralja Petra Svačića 1d, H R -31000 Osijek (Croatia); Lepeduš, Hrvoje, E-mail: hlepedus@yahoo.com [Faculty of Humanities and Social Sciences, Josip Juraj Strossmayer University of Osijek, Lorenza Jägera 9, HR-31000 Osijek (Croatia); Cesar, Vera, E-mail: vcesarus@yahoo.com [Josip Juraj Strossmayer University of Osijek, Department of Biology, Ulica cara Hadrijana 8/A, H R -31000 Osijek (Croatia)

    2016-06-15

    Highlights: • Cobalt (Co{sup 2+}) impaired the function of oxygen evolving complex (OEC) in L. minor L. • Electron transport through PSII components varied depending on Co{sup 2+} concentration. • K-band was proven to be suitable parameter for investigation of Co{sup 2+} toxicity. • Increased lipid peroxidation level showed early oxidative damage induced by Co{sup 2+}. - Abstract: The effect of two concentrations of cobalt (Co{sup 2+}) on photosynthetic activity and antioxidative response in Lemna minor L. were assessed 24, 48 and 72 h after the start of the exposure. Higher concentration of cobalt (1 mM) induced growth inhibition while lower concentration (0.01 mM) increased photosynthetic pigments content. Analysis of chlorophyll a fluorescence transients revealed high sensitivity of photosystem II primary photochemistry to excess of Co{sup 2+} especially at the higher concentration where decreased electron transport beyond primary quinone acceptor Q{sub A}{sup −} and impaired function of oxygen evolving complex (OEC) was observed. Due to impairment of OEC, oxygen production was decreased at higher Co{sup 2+} concentration. Activity of superoxide dismutase was mainly inhibited while lipid peroxidation increased, at both concentrations, indicating that cobalt-induced oxidative damage after short exposure and moreover, susceptibility of the membranes in the cell to cobalt toxicity. Results obtained in this study suggest possible application of used parameters as tools in assessment of early damage caused by metals.

  2. Response of Lemna minor L. to short-term cobalt exposure: The effect on photosynthetic electron transport chain and induction of oxidative damage

    International Nuclear Information System (INIS)

    Begović, Lidija; Mlinarić, Selma; Antunović Dunić, Jasenka; Katanić, Zorana; Lončarić, Zdenko; Lepeduš, Hrvoje; Cesar, Vera

    2016-01-01

    Highlights: • Cobalt (Co"2"+) impaired the function of oxygen evolving complex (OEC) in L. minor L. • Electron transport through PSII components varied depending on Co"2"+ concentration. • K-band was proven to be suitable parameter for investigation of Co"2"+ toxicity. • Increased lipid peroxidation level showed early oxidative damage induced by Co"2"+. - Abstract: The effect of two concentrations of cobalt (Co"2"+) on photosynthetic activity and antioxidative response in Lemna minor L. were assessed 24, 48 and 72 h after the start of the exposure. Higher concentration of cobalt (1 mM) induced growth inhibition while lower concentration (0.01 mM) increased photosynthetic pigments content. Analysis of chlorophyll a fluorescence transients revealed high sensitivity of photosystem II primary photochemistry to excess of Co"2"+ especially at the higher concentration where decreased electron transport beyond primary quinone acceptor Q_A"− and impaired function of oxygen evolving complex (OEC) was observed. Due to impairment of OEC, oxygen production was decreased at higher Co"2"+ concentration. Activity of superoxide dismutase was mainly inhibited while lipid peroxidation increased, at both concentrations, indicating that cobalt-induced oxidative damage after short exposure and moreover, susceptibility of the membranes in the cell to cobalt toxicity. Results obtained in this study suggest possible application of used parameters as tools in assessment of early damage caused by metals.

  3. Assessment of oxidized low density lipoprotein, as atherosclerosis risk marker in type 1 diabetic children with short history of diabetes mellitus

    International Nuclear Information System (INIS)

    Hamad, A.; Hasan, S.; Qureshi, H.J.; Sami, W.

    2010-01-01

    To evaluate the type-1 diabetic children for early atherosclerosis risk by measuring serum oxidized lipoprotein in relation with glycemic control. Recent studies indicate that systemic markers of inflammation can identify subjects at high risk of cardiovascular disease (CVD). Oxidized low density lipoprotein (OxLDL) levels have been regarded as one of the independent determinants of atherosclerosis. Methods: This cross sectional study involved a total 79 subjects including 39 type 1 diabetics and 40 non-diabetic controls between the ages of 9 to 16 years. A detailed medical history was taken from each subject and the individuals with history of type-1 diabetes underwent clinical examination. Individuals with obesity, hypertension, smoking, and chronic infections, autoimmune and renal diseases were excluded. Serum concentrations of glucose and lipid profile were measured in duplicate by kits based on enzymatic methods. OxLDL was measured in duplicate by using standard enzyme linked immunosorbent assay (ELISA) method. Haemoglobin A1c and Body mass index (BMI) were also measured. Results: Diabetic patients had significantly elevated levels of blood glucose (320.1vs 97) and HbA1c (10.3% vs 5.21%) as compared to controls (p 0.05). Conclusion: OxLDL is a strong independent risk marker for atherosclerosis observed in diagnosed old age patients of CVD but in present study we could not find statistically significant elevated levels of OxLDL in young diabetic subjects with short duration of diabetes. (author)

  4. Effect of Short-Term High Fat Diet Inducing Obesity on Hematological, Some Biochemical Parameters and Testicular Oxidative Stress in Male Rats

    Directory of Open Access Journals (Sweden)

    Sherif M. Shawky

    2015-10-01

    Full Text Available Obesity constitutes a health problem due to its increasing worldwide prevalence. Among the health detriments caused by obesity, reproduction is disrupted. Some studies have shown a relationship between obesity and infertility, but until now it remains controversial. The objective of the current work was to examine the effect of diet-induced obesity on blood parameters, liver and kidney function tests, lipid profile and testicular oxidative stress. For that purpose, Male rats were fed ad libitum with a standard diet (control group; n.= 15 and high fat diet (HFD group; n.= 15 for 6 weeks. Hematological parameters, urea, creatinine, albumin were similar between the two groups. Intergroup testosterone levels were also comparable. The high fat diet induced significant increase in serum triglycerides, cholesterol, low density lipoprotein and very low density lipoprotein cholesterol concentrations. This diet also increases significantly alanine aminotransferase and aspartate aminotransferase activities and decreased total protein level and high-density lipoprotein cholesterol concentration. Furthermore, HFD showed a significant increasing in malondialdehyde contents in testes and decreasing in superoxide dismutase activity, the results of this study concluded that short-term high fat diet affect on liver enzymes and causing oxidative stress in testes.

  5. Inhaled nitric oxide improves short term memory and reduces the inflammatory reaction in a mouse model of mild traumatic brain injury.

    Science.gov (United States)

    Liu, Ping; Li, Yong-Sheng; Quartermain, David; Boutajangout, Allal; Ji, Yong

    2013-07-19

    Although the mechanisms underlying mild traumatic brain injury (mTBI) are becoming well understood, treatment options are still limited. In the present study, mTBI was induced by a weight drop model to produce a closed head injury to mice and the effect of inhaled nitric oxide (INO) was evaluated by a short term memory task (object recognition task) and immunohistochemical staining of glial fibrillary acidic protein (GFAP) and CD45 for the detection of reactive astrocytes and microglia. Results showed that mTBI model did not produce brain edema, skull fracture or sensorimotor coordination dysfunctions. Mice did however exhibit a significant deficit in short term memory (STM) and strong inflammatory reaction in the ipsilateral cortex and hippocampus compared to sham-injured controls 24h after mTBI. Additional groups of untreated mice tested 3 and 7 days later, demonstrated that recognition memory had recovered to normal levels by Day 3. Mice treated with 10ppm INO for 4 or 8h, beginning immediately after TBI demonstrated significantly improved STM at 24h when compared with room air controls (pshort durations of INO prevents this memory loss and also attenuates the inflammatory response. These findings may have relevance for the treatment of patients diagnosed with concussion. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. High-energy X-ray diffraction studies of short- and intermediate-range structure in oxide glasses

    International Nuclear Information System (INIS)

    Suzuya, Kentaro

    2002-01-01

    The feature of high-energy X-ray diffraction method is explained. The oxide glasses studies by using BL04B2, high-energy X-ray diffraction beam line of SPring-8, and the random system materials by high-energy monochromatic X-ray diffraction are introduced. An advantage of third generation synchrotron radiation is summarized. On SPring-8, the high-energy X-ray diffraction experiments of random system are carried out by BL04B2 and BL14B1 beam line. BL04B2 can select Si (111)(E=37.8 keV, λ=0.033 nm) and Si(220)(E=61.7 keV, λ=0.020 nm) as Si monochromator. The intermediate-range structure of (MgO) x (P 2 O 5 ) 1-x glass ,MgP 2 O 6 glass, B 2 O 3 glass, SiO 2 and GeO 2 are explained in detail. The future and application of high-energy X-ray diffraction are stated. (S.Y.)

  7. Short-term and latent post-settlement effects associated with elevated temperature and oxidative stress on larvae from the coral Porites astreoides

    Science.gov (United States)

    Ross, C.; Ritson-Williams, R.; Olsen, K.; Paul, V. J.

    2013-03-01

    Coral reefs across the Caribbean are undergoing unprecedented rates of decline in coral cover during the last three decades, and coral recruitment is one potential process that could aid the recovery of coral populations. To better understand the effects of climate change on coral larval ecology, the larvae of Porites astreoides were studied to determine the immediate and post-settlement effects of elevated temperature and associated oxidative stress. Larvae of Porites astreoides were exposed to 27 °C (ambient) and +3.0 °C (elevated temperature) seawater for a short duration of 24 h; then, a suite of physiological parameters were measured to determine the extent of sublethal stress. Following the +3.0 °C treatment, larvae did not show a significant difference in maximum quantum yield of PSII ( F v/ F m) or respiratory demand when compared to controls maintained at 27 °C. The addition of micromolar concentrations of hydrogen peroxide did not impact respiration or photochemical efficiency. Catalase activity in the larvae increased (>60 %) following exposure to elevated temperature when compared to the controls. Short-term larval survival and settlement and metamorphosis were not affected by increased temperature or the H2O2 treatment. However, the settled spat that were exposed to elevated temperature underwent a 99 % reduction in survival compared to 90 % reduction for the control spat when examined 24 days following the deployment of 4-day-old settled spat on settlement tiles in the field. These results show that short-term exposure to some stressors might have small impacts on coral physiology, and no effects on larval survival, settlement and metamorphosis. However, due to post-settlement mortality, these stressors can cause a significant reduction in coral recruitment.

  8. Defect ordering in aliovalently doped cubic zirconia from first principles

    International Nuclear Information System (INIS)

    Bogicevic, A.; Wolverton, C.; Crosbie, G.M.; Stechel, E.B.

    2001-01-01

    Defect ordering in aliovalently doped cubic-stabilized zirconia is studied using gradient corrected density-functional calculations. Intra- and intersublattice ordering interactions are investigated for both cation (Zr and dopant ions) and anion (oxygen ions and vacancies) species. For yttria-stabilized zirconia, the crystal structure of the experimentally identified, ordered compound δ-Zr 3 Y 4 O 12 is established, and we predict metastable zirconia-rich ordered phases. Anion vacancies repel each other at short separations, but show an energetic tendency to align as third-nearest neighbors along directions. Calculations with divalent (Be, Mg, Ca, Sr, Ba) and trivalent (Y, Sc, B, Al, Ga, In) oxides show that anion vacancies prefer to be close to the smaller of the cations (Zr or dopant ion). When the dopant cation is close in size to Zr, the vacancies show no particular preference, and are thus less prone to be bound preferentially to any particular cation type when the vacancies traverse such oxides. This ordering tendency offers insight into the observed high conductivity of Y 2 O 3 - and Sc 2 O 3 -stabilized zirconia, as well as recent results using, e.g., lanthanide oxides. The calculations point to In 2 O 3 as a particularly promising stabilizer for high ionic conductivity. Thus we are able to directly link (thermodynamic) defect ordering to (kinetic) ionic conductivity in cubic-stabilized zirconia using first-principles atomistic calculations

  9. Xenoestrogenic short ethoxy chain nonylphenol is oxidized by a flavoprotein alcohol dehydrogenase from Ensifer sp. strain AS08.

    Science.gov (United States)

    Liu, Xin; Tani, Akio; Kimbara, Kazuhide; Kawai, Fusako

    2007-01-01

    The ethoxy chains of short ethoxy chain nonylphenol (NPEO(av2.0), containing average 2.0 ethoxy units) were dehydrogenated by cell-free extracts from Ensifer sp. strain AS08 grown on a basal medium supplemented with NPEO(av2.0). The reaction was coupled with the reduction in 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide and phenazine methosulfate. The enzyme (NPEO(av2.0) dehydrogenase; NPEO-DH) was purified to homogeneity with a yield of 20% and a 56-fold increase in specific activity. The molecular mass of the native enzyme was 120 kDa, consisting of two identical monomer units (60 kDa). The gene encoding NPEO-DH was cloned, which consisted of 1,659 bp, corresponding to a protein of 553 amino acid residues. The deduced amino acid sequence agreed with the N-terminal amino acid sequence of the purified NPEO-DH. The presence of a flavin adenine dinucleotide (FAD)-binding motif and glucose-methanol-choline (GMC) oxidoreductase signature motifs strongly suggested that the enzyme belongs to the GMC oxidoreductase family. The protein exhibited homology (40-45% identity) with several polyethylene glycol dehydrogenases (PEG-DHs) of this family, but the identity was lower than those (approximately 58%) among known PEG-DHs. The substrate-binding domain was more hydrophobic compared with those of glucose oxidase and PEG-DHs. The recombinant protein had the same molecular mass as the purified NPEO-DH and dehydrogenated PEG400-2000, NPEO(av2.0) and its components, and NPEOav10, but only slight or no activity was found using diethylene glycol, triethylene glycol, and PEG200.

  10. Defect Chemistry and Electrical Conductivity of Sm-Doped La1-xSrxCoO3-δ for Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Björketun, Mårten; Castelli, Ivano Eligio; Rossmeisl, Jan

    2017-01-01

    We have calculated the electrical conductivity of the solid oxide fuel cell (SOFC) cathode contact material La1-xSrxCoO3-δ at 900 K. Experimental trends in conductivity against x, and against δ for fixed x, are correctly reproduced for x ≲ 0.8. Furthermore, we have studied the chemistry of neutral...

  11. Facts about Birth Defects

    Science.gov (United States)

    ... label> Information For… Media Policy Makers Facts about Birth Defects Language: English (US) Español (Spanish) Recommend on ... having a baby born without a birth defect. Birth Defects Are Common Every 4 ½ minutes, a ...

  12. Neural Tube Defects

    Science.gov (United States)

    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In ...

  13. Strained interface defects in silicon nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Benjamin G.; Stradins, Paul [National Center for Photovoltaics, National Renewable Energy Laboratory, Golden, CO (United States); Hiller, Daniel; Zacharias, Margit [IMTEK - Faculty of Engineering, Albert-Ludwigs-University Freiburg (Germany); Luo, Jun-Wei; Beard, Matthew C. [Chemical and Materials Science, National Renewable Energy Laboratory, Golden, CO (United States); Semonin, Octavi E. [Chemical and Materials Science, National Renewable Energy Laboratory, Golden, CO (United States); Department of Physics, University of Colorado, Boulder, CO (United States)

    2012-08-07

    The surface of silicon nanocrystals embedded in an oxide matrix can contain numerous interface defects. These defects strongly affect the nanocrystals' photoluminescence efficiency and optical absorption. Dangling-bond defects are nearly eliminated by H{sub 2} passivation, thus decreasing absorption below the quantum-confined bandgap and enhancing PL efficiency by an order of magnitude. However, there remain numerous other defects seen in absorption by photothermal deflection spectroscopy; these defects cause non-radiative recombination that limits the PL efficiency to <15%. Using atomistic pseudopotential simulations, we attribute these defects to two specific types of distorted bonds: Si-Si and bridging Si-O-Si bonds between two Si atoms at the nanocrystal surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Fatal hepatic short-chain L-3-hydroxyacyl-coenzyme A dehydrogenase deficiency: clinical, biochemical, and pathological studies on three subjects with this recently identified disorder of mitochondrial beta-oxidation

    NARCIS (Netherlands)

    Bennett, M. J.; Spotswood, S. D.; Ross, K. F.; Comfort, S.; Koonce, R.; Boriack, R. L.; IJlst, L.; Wanders, R. J.

    1999-01-01

    This report describes the clinical, biochemical, and pathological findings in three infants with hepatic short-chain L-3-hydroxyacyl-coenzyme A dehydrogenase (SCHAD) deficiency, a recently recognized disorder of the mitochondrial oxidation of straight-chain fatty acids. Candidate subjects were

  15. Isolated 2-methylbutyrylglycinuria caused by short/branched-chain acyl-CoA dehydrogenase deficiency: identification of a new enzyme defect, resolution of its molecular basis, and evidence for distinct acyl-CoA dehydrogenases in isoleucine and valine metabolism

    NARCIS (Netherlands)

    Andresen, B. S.; Christensen, E.; Corydon, T. J.; Bross, P.; Pilgaard, B.; Wanders, R. J.; Ruiter, J. P.; Simonsen, H.; Winter, V.; Knudsen, I.; Schroeder, L. D.; Gregersen, N.; Skovby, F.

    2000-01-01

    Acyl-CoA dehydrogenase (ACAD) defects in isoleucine and valine catabolism have been proposed in clinically diverse patients with an abnormal pattern of metabolites in their urine, but they have not been proved enzymatically or genetically, and it is unknown whether one or two ACADs are involved. We

  16. High current density GaAs/Si rectifying heterojunction by defect free Epitaxial Lateral overgrowth on Tunnel Oxide from nano-seed.

    Science.gov (United States)

    Renard, Charles; Molière, Timothée; Cherkashin, Nikolay; Alvarez, José; Vincent, Laetitia; Jaffré, Alexandre; Hallais, Géraldine; Connolly, James Patrick; Mencaraglia, Denis; Bouchier, Daniel

    2016-05-04

    Interest in the heteroepitaxy of GaAs on Si has never failed in the last years due to the potential for monolithic integration of GaAs-based devices with Si integrated circuits. But in spite of this effort, devices fabricated from them still use homo-epitaxy only. Here we present an epitaxial technique based on the epitaxial lateral overgrowth of micrometer scale GaAs crystals on a thin SiO2 layer from nanoscale Si seeds. This method permits the integration of high quality and defect-free crystalline GaAs on Si substrate and provides active GaAs/Si heterojunctions with efficient carrier transport through the thin SiO2 layer. The nucleation from small width openings avoids the emission of misfit dislocations and the formation of antiphase domains. With this method, we have experimentally demonstrated for the first time a monolithically integrated GaAs/Si diode with high current densities of 10 kA.cm(-2) for a forward bias of 3.7 V. This epitaxial technique paves the way to hybrid III-V/Si devices that are free from lattice-matching restrictions, and where silicon not only behaves as a substrate but also as an active medium.

  17. Response of Lemna minor L. to short-term cobalt exposure: The effect on photosynthetic electron transport chain and induction of oxidative damage.

    Science.gov (United States)

    Begović, Lidija; Mlinarić, Selma; Antunović Dunić, Jasenka; Katanić, Zorana; Lončarić, Zdenko; Lepeduš, Hrvoje; Cesar, Vera

    2016-06-01

    The effect of two concentrations of cobalt (Co(2+)) on photosynthetic activity and antioxidative response in Lemna minor L. were assessed 24, 48 and 72h after the start of the exposure. Higher concentration of cobalt (1mM) induced growth inhibition while lower concentration (0.01mM) increased photosynthetic pigments content. Analysis of chlorophyll a fluorescence transients revealed high sensitivity of photosystem II primary photochemistry to excess of Co(2+) especially at the higher concentration where decreased electron transport beyond primary quinone acceptor QA(-) and impaired function of oxygen evolving complex (OEC) was observed. Due to impairment of OEC, oxygen production was decreased at higher Co(2+) concentration. Activity of superoxide dismutase was mainly inhibited while lipid peroxidation increased, at both concentrations, indicating that cobalt-induced oxidative damage after short exposure and moreover, susceptibility of the membranes in the cell to cobalt toxicity. Results obtained in this study suggest possible application of used parameters as tools in assessment of early damage caused by metals. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. La interstitial defect-induced insulator-metal transition in the oxide heterostructures LaAl O3 /SrTi O3

    Science.gov (United States)

    Zhou, Jun; Yang, Ming; Feng, Yuan Ping; Rusydi, Andrivo

    2017-11-01

    Perovskite oxide interfaces have attracted tremendous research interest for their fundamental physics and promising all-oxide electronic applications. Here, based on first-principles calculations, we propose a surface La interstitial promoted interface insulator-metal transition in LaAl O3 /SrTi O3 (110). Compared with surface oxygen vacancies, which play a determining role on the insulator-metal transition of LaAl O3 /SrTi O3 (001) interfaces, we find that surface La interstitials can be more experimentally realistic and accessible for manipulation and more stable in an ambient atmospheric environment. Interestingly, these surface La interstitials also induce significant spin-splitting states with a Ti dy z/dx z character at a conducting LaAl O3 /SrTi O3 (110) interface. On the other hand, for insulating LaAl O3 /SrTi O3 (110) (<4 unit cells LaAl O3 thickness), a distortion between La (Al) and O atoms is found at the LaAl O3 side, partially compensating the polarization divergence. Our results reveal the origin of the metal-insulator transition in LaAl O3 /SrTi O3 (110) heterostructures, and also shed light on the manipulation of the superior properties of LaAl O3 /SrTi O3 (110) for different possibilities in electronic and magnetic applications.

  19. Part 1: The effect of lattice defects on the sintering of lithium fluoride; Part 2: The morphology of calcium oxide from calcium carbonate decomposition

    International Nuclear Information System (INIS)

    Fenwick, D.M.

    1990-09-01

    Our motivation for studying the effect of lattice defects on sintering kinetics came from a theory by Searcy concerning surface melting of solids. Surface melting has been shown to occur in ice, argon, and lead at temperatures below the melting point. While surface melting of this sort is an equilibrium phenomenon, Searcy has predicted that surface melting may also occur in a non-equilibrium situation -- when a solid is being rapidly heated and has a below-equilibrium concentration of vacancies for the temperature reached. To test the surface melting theory we have compared the density changes of two different types of powder compacts of lithium fluoride after subjecting both to the same fast-firing heat treatment. One type of compact consisted of powder originating from a crystal which he had quenched from a high temperature, and the other consisted of powder from a crystal which we had annealed at a lower temperature. When calcite is decomposed in vacuum, CaO is sometimes found in two distinguishable layers. Both layers are comprised of fairly uniformly sized, cylindrical rods on the order of 10 nm in diameter with the normal NaCl-type crystal structure. The outer layer consists of ∼1 μm diameter bundles of rods separated by ∼1 μm wide cracks. The second layer, adjacent to any undecomposed calcite -- the ''intermediate layer'' -- probably consists of rods which are relatively evenly spaced. Because sintering is negligible when calcite decomposition occurs below 700 degree C in a vacuum of 10 -3 torr or less, the outer layer is probably formed by a diffusionless, cooperative re-packing of CaO rods first formed with the uniform spacing characteristic of the intermediate layer. 35 refs., 25 figs., 6 tabs

  20. Preparation of magnetic and bioactive calcium zinc iron silicon oxide composite for hyperthermia treatment of bone cancer and repair of bone defects.

    Science.gov (United States)

    Jiang, Yumin; Ou, Jun; Zhang, Zhanhe; Qin, Qing-Hua

    2011-03-01

    In this paper, a calcium zinc iron silicon oxide composite (CZIS) was prepared using the sol-gel method. X-ray diffraction (XRD) was then employed to test the CZIS composite. The results from the test showed that the CZIS had three prominent crystalline phases: Ca(2)Fe(1.7)Zn(0.15)Si(0.15)O(5), Ca(2)SiO(4), and ZnFe(2)O(4). Calorimetric measurements were then performed using a magnetic induction furnace. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis were conducted to confirm the growth of a precipitated hydroxyapatite phase after immersion in simulated body fluid (SBF). Cell culture experiments were also carried out, showing that the CZIS composite more visibly promoted osteoblast proliferation than ZnFe(2)O(4) glass ceramic and HA, and osteoblasts adhered and spread well on the surfaces of composite samples.

  1. Defect pin behaviour in the DFR

    International Nuclear Information System (INIS)

    Sloss, W.M.; Bagley, K.Q.; Edmonds, E.; Potter, P.E.

    1979-01-01

    A program of defective fuel pin irradiations has been carried out in the DFR. This program employed fuel pins which had failed during previous irradiations (natural defects) and pins in which simulated failures (artificial defects) had been induced prior to irradiation or during an intermediate examination stage at moderate or substantial burnups. The artificial defects simulated longitudinal ruptures and were normally located at positions near the top, middle and bottom of the pin where clad temperatures were 450, 540 and 630 0 C respectively. The fuel was mixed U-Pu oxide, and fuel form, stoichiometry, clad type, pin diameter, linear rating, and burnup were among the variables examined. The defect pin tests were normally carried out in single pin or trefoil type vehicles. After irradiation all the pins were subjected to the normal nondestructive examination procedures and the visual, radiographic, gamma-scanning, and dimensional change results are presented. Several pins were destructively examined and the metallographic data are discussed

  2. Thermoacoustic Imaging and Therapy Guidance based on Ultra-short Pulsed Microwave Pumped Thermoelastic Effect Induced with Superparamagnetic Iron Oxide Nanoparticles.

    Science.gov (United States)

    Wen, Liewei; Yang, Sihua; Zhong, Junping; Zhou, Quan; Xing, Da

    2017-01-01

    Multifunctional nanoparticle-mediated imaging and therapeutic techniques are promising modalities for accurate localization and targeted treatment of cancer in clinical settings. Thermoacoustic (TA) imaging is highly sensitive to detect the distribution of water, ions or specific nanoprobes and provides excellent resolution, good contrast and superior tissue penetrability. TA therapy is a potential non-invasive approach for the treatment of deep-seated tumors. In this study, human serum albumin (HSA)-functionalized superparamagnetic iron oxide nanoparticle (HSA-SPIO) is used as a multifunctional nanoprobe with clinical application potential for MRI, TA imaging and treatment of tumor. In addition to be a MRI contrast agent for tumor localization, HSA-SPIO can absorb pulsed microwave energy and transform it into shockwave via the thermoelastic effect. Thereby, the reconstructed TA image by detecting TA signal is expected to be a sensitive and accurate representation of the HSA-SPIO accumulation in tumor. More importantly, owing to the selective retention of HSA-SPIO in tumor tissues and strong TA shockwave at the cellular level, HSA-SPIO induced TA effect under microwave-pulse radiation can be used to highly-efficiently kill cancer cells and inhibit tumor growth. Furthermore, ultra-short pulsed microwave with high excitation efficiency and deep penetrability in biological tissues makes TA therapy a highly-efficient anti-tumor modality on the versatile platform. Overall, HSA-SPIO mediated MRI and TA imaging would offer more comprehensive diagnostic information and enable dynamic visualization of nanoagents in the tumorous tissue thereby tumor-targeted therapy.

  3. Hydrogen production with short contact time. Catalytic partial oxidation of hydrocarbons and oxygenated compounds: Recent advances in pilot- and bench-scale testing and process design

    Energy Technology Data Exchange (ETDEWEB)

    Guarinoni, A.; Ponzo, R.; Basini, L. [ENI Refining and Marketing Div., San Donato Milanese (Italy)

    2010-12-30

    ENI R and D has been active for fifteen years in the development of Short Contact Time - Catalytic Partial Oxidation (SCT-CPO) technologies for producing Hydrogen/Synthesis Gas. From the beginning the experimental work addressed either at defining the fundamental principles or the technical and economical potential of the technology. Good experimental responses, technical solutions' simplicity and flexibility, favourable techno-economical evaluations promoted the progressive widening of the field of the investigations. From Natural Gas (NG) the range of ''processable'' Hydrocarbons extended to Liquefied Petroleum Gas (LPG) and Gasoils, including those characterised by high levels of unsaturated and sulphurated molecules and, lately, to other compounds with biological origin. The extensive work led to the definition of different technological solutions, grouped as follows: Technology 1: Air Blown SCT-CPO of Gaseous Hydrocarbons and/or Light Compounds with biological origin Technology 2: Enriched Air/Oxygen Blown SCT-CPO of Gaseous Hydrocarbons and/or Light Compounds with biological origin Technology 3: Enriched Air/Oxygen Blown SCT-CPO of Liquid Hydrocarbons and/or Compounds with biological origin Recently, the licence rights on a non-exclusive basis for the commercialisation of SCT-CPO based processes for H{sub 2}/Synthesis gas production from light hydrocarbons with production capacity lower than 5,000 Nm{sup 3}/h of H{sub 2} or 7,500 Nm3/h of syngas have been assigned to two external companies. In parallel, development of medium- and large-scale plant solutions is progressing within the ENI group framework. These last activities are addressed to the utilisation of SCT-CPO for matching the variable Hydrogen demand in several contexts of oil refining operation. This paper will report on the current status of SCT-CPO with a focus on experimental results obtained, either at pilot- and bench- scale level. (orig.)

  4. Influence of the gel thickness on in vivo hyaline cartilage regeneration induced by double-network gel implanted at the bottom of a large osteochondral defect: short-term results.

    Science.gov (United States)

    Matsuda, Hidetoshi; Kitamura, Nobuto; Kurokawa, Takayuki; Arakaki, Kazunobu; Gong, Jian Ping; Kanaya, Fuminori; Yasuda, Kazunori

    2013-01-31

    A double-network (DN) gel, which is composed of poly(2-acrylamido-2-methylpropanesulfonic acid) and poly(N,N'-dimethyl acrylamide), can induce hyaline cartilage regeneration in vivo in a large osteochondral defect. The purpose of this study was to clarify the influence of the thickness of the implanted DN gel on the induction ability of hyaline cartilage regeneration. Thirty-eight mature rabbits were used in this study. We created an osteochondral defect having a diameter of 4.3-mm in the patellofemoral joint. The knees were randomly divided into 4 groups (Group I: 0.5-mm thick gel, Group II: 1.0-mm thick gel, Group III: 5.0-mm thick gel, and Group IV: untreated control). Animals in each group were further divided into 3 sub-groups depending on the gel implant position (2.0-, 3.0-, or 4.0-mm depth from the articular surface) in the defect. The regenerated tissues were evaluated with the Wayne's gross and histological grading scales and real time PCR analysis of the cartilage marker genes at 4 weeks. According to the total Wayne's score, when the depth of the final vacant space was set at 2.0 mm, the scores in Groups I, II, and III were significantly greater than that Group IV (phyaline cartilage regeneration as the 5.0-mm thick DN gel plug. However, the induction ability of the 0.5-mm thick sheet was significantly lower when compared with the 1.0-mm thick gel sheet. The 1.0-mm DN gel sheet is a promising device to establish a cell-free cartilage regeneration strategy that minimizes bone loss from the gel implantation.

  5. Influence of the gel thickness on in vivo hyaline cartilage regeneration induced by double-network gel implanted at the bottom of a large osteochondral defect: Short-term results

    Directory of Open Access Journals (Sweden)

    Matsuda Hidetoshi

    2013-01-01

    Full Text Available Abstract Background A double-network (DN gel, which is composed of poly(2-acrylamido-2-methylpropanesulfonic acid and poly(N,N’-dimethyl acrylamide, can induce hyaline cartilage regeneration in vivo in a large osteochondral defect. The purpose of this study was to clarify the influence of the thickness of the implanted DN gel on the induction ability of hyaline cartilage regeneration. Methods Thirty-eight mature rabbits were used in this study. We created an osteochondral defect having a diameter of 4.3-mm in the patellofemoral joint. The knees were randomly divided into 4 groups (Group I: 0.5-mm thick gel, Group II: 1.0-mm thick gel, Group III: 5.0-mm thick gel, and Group IV: untreated control. Animals in each group were further divided into 3 sub-groups depending on the gel implant position (2.0-, 3.0-, or 4.0-mm depth from the articular surface in the defect. The regenerated tissues were evaluated with the Wayne’s gross and histological grading scales and real time PCR analysis of the cartilage marker genes at 4 weeks. Results According to the total Wayne’s score, when the depth of the final vacant space was set at 2.0 mm, the scores in Groups I, II, and III were significantly greater than that Group IV (p  Conclusions The 1.0-mm thick DN gel sheet had the same ability to induce hyaline cartilage regeneration as the 5.0-mm thick DN gel plug. However, the induction ability of the 0.5-mm thick sheet was significantly lower when compared with the 1.0-mm thick gel sheet. The 1.0-mm DN gel sheet is a promising device to establish a cell-free cartilage regeneration strategy that minimizes bone loss from the gel implantation.

  6. Craniotomy Frontal Bone Defect

    African Journals Online (AJOL)

    2018-03-01

    Mar 1, 2018 ... Defect reconstruction and fixation of the graft: The defect of ... where all loose fragments of fractured frontal bone was removed via the ... Mandible. • Ilium. • Allograft ... pediatric patients owing to skull growth. Thus, autologous ...

  7. Congenital platelet function defects

    Science.gov (United States)

    ... pool disorder; Glanzmann's thrombasthenia; Bernard-Soulier syndrome; Platelet function defects - congenital ... Congenital platelet function defects are bleeding disorders that cause reduced platelet function. Most of the time, people with these disorders have ...

  8. Selected topics in high temperature chemistry defect chemistry of solids

    CERN Document Server

    Johannesen, Ø

    2013-01-01

    The properties of materials at high temperature play a vital role in their processing and practical use. The real properties of materials at elevated temperatures are very often governed by defects in their structure. Lattice defects may consist of point defects like vacancies, interstitial atoms or substituted atoms. These classes are discussed in general and specifically for oxides, nitrides, carbides and sulfides. Defect aggregates, shear structures and adaptive structures are also described. Special attention is paid to hydrogen defects which seem to play an important role in several mater

  9. Defect of the Eyelids.

    Science.gov (United States)

    Lu, Guanning Nina; Pelton, Ron W; Humphrey, Clinton D; Kriet, John David

    2017-08-01

    Eyelid defects disrupt the complex natural form and function of the eyelids and present a surgical challenge. Detailed knowledge of eyelid anatomy is essential in evaluating a defect and composing a reconstructive plan. Numerous reconstructive techniques have been described, including primary closure, grafting, and a variety of local flaps. This article describes an updated reconstructive ladder for eyelid defects that can be used in various permutations to solve most eyelid defects. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Fibrous metaphyseal defects

    International Nuclear Information System (INIS)

    Ritschl, P.; Hajek, P.C.; Pechmann, U.

    1989-01-01

    Sixteen patients with fibrous metaphyseal defects were examined with both plain radiography and magnetic resonance (MR) imaging. Depending on the age of the fibrous metaphyseal defects, characteristic radiomorphologic changes were found which correlated well with MR images. Following intravenous Gadolinium-DTPA injection, fibrous metaphyseal defects invariably exhibited a hyperintense border and signal enhancement. (orig./GDG)

  11. Birth Defects (For Parents)

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Birth Defects KidsHealth / For Parents / Birth Defects What's in ... Prevented? Print en español Anomalías congénitas What Are Birth Defects? While still in the womb, some babies ...

  12. The electrical properties of indium oxide thin films. In-situ Hall effect measurements to investigate the influence of point defects and grain boundaries; Die elektrischen Eigenschaften von Indiumoxid-Duennschichten. In-situ Hall-Effekt-Messungen zur Aufklaerung des Einflusses von Punktdefekten und Korngrenzen

    Energy Technology Data Exchange (ETDEWEB)

    Frischbier, Mareike

    2015-08-15

    Despite the wide application of indium oxide as transparent conducting material, basic mechanisms of its high conductivity are not understood yet. However, indium is scarce and the development of alternative materials for indium oxide is necessary. This requires a detailed understanding of the conductivity mechanisms. The electrical conductivity of undoped and doped indium oxide is given by defects. Thus, the influence of point defects and grain boundaries in sputtered indium oxide thin films is investigated here. This dissertation contributes to a more profound understanding of the conductivity mechanisms of indium oxide: grain boundary scattering is identified as the most important limiting scattering mechanism and the influence of doping elements on this property is shown. Dominant point defects in oxide materials are commonly investigated in literature by conductivity relaxation measurements depending on oxygen partial pressure. Usually, carrier mobility is assumed to be constant when analysing the results. However, this assumption is incorrect and can lead to a misinterpretation of data. Therefore, relaxation measurements are conducted as part of this dissertation to directly measure charge carrier concentration and mobility for the first time. For this purpose, a new experimental setup has been developed which enables measuring the Hall effect in-situ depending on oxygen partial pressure, temperature and total pressure. Relaxation measurements are conducted as part of this dissertation to show that charge carrier mobility is not constant, but strongly depends on carrier concentration. Further measurements verify that the scattering of charge carriers at grain boundaries is one main reason. In addition, the influence of deposition parameters of the sputter deposition process and doping (dopant element and concentration) on carrier concentration and mobility at room temperature is studied. The experimental results show that the doping elements influence both

  13. Defect tolerance in resistor-logic demultiplexers for nanoelectronics.

    Science.gov (United States)

    Kuekes, Philip J; Robinett, Warren; Williams, R Stanley

    2006-05-28

    Since defect rates are expected to be high in nanocircuitry, we analyse the performance of resistor-based demultiplexers in the presence of defects. The defects observed to occur in fabricated nanoscale crossbars are stuck-open, stuck-closed, stuck-short, broken-wire, and adjacent-wire-short defects. We analyse the distribution of voltages on the nanowire output lines of a resistor-logic demultiplexer, based on an arbitrary constant-weight code, when defects occur. These analyses show that resistor-logic demultiplexers can tolerate small numbers of stuck-closed, stuck-open, and broken-wire defects on individual nanowires, at the cost of some degradation in the circuit's worst-case voltage margin. For stuck-short and adjacent-wire-short defects, and for nanowires with too many defects of the other types, the demultiplexer can still achieve error-free performance, but with a smaller set of output lines. This design thus has two layers of defect tolerance: the coding layer improves the yield of usable output lines, and an avoidance layer guarantees that error-free performance is achieved.

  14. Surface defects on the Gd{sub 2}Zr{sub 2}O{sub 7} oxide films grown on textured NiW technical substrates by chemical solution method

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Y., E-mail: yuezhao@sjtu.edu.cn [School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, 200240 Shanghai (China); Department of Energy Conversion and Storage, Technical University of Denmark, 4000 Roskilde (Denmark); Opata, Yuri A. [Department of Energy Conversion and Storage, Technical University of Denmark, 4000 Roskilde (Denmark); Wu, W. [School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, 200240 Shanghai (China); Grivel, J.C. [Department of Energy Conversion and Storage, Technical University of Denmark, 4000 Roskilde (Denmark)

    2017-02-15

    Epitaxial growth of oxide thin films has attracted much interest because of their broad applications in various fields. In this study, we investigated the microstructure of textured Gd{sub 2}Zr{sub 2}O{sub 7} films grown on (001)〈100〉 orientated NiW alloy substrates by a chemical solution deposition (CSD) method. The aging effect of precursor solution on defect formation was thoroughly investigated. A slight difference was observed between the as-obtained and aged precursor solutions with respect to the phase purity and global texture of films prepared using these solutions. However, the surface morphologies are different, i.e., some regular-shaped regions (mainly hexagonal or dodecagonal) were observed on the film prepared using the as-obtained precursor, whereas the film prepared using the aged precursor exhibits a homogeneous structure. Electron backscatter diffraction and scanning electron microscopy analyses showed that the Gd{sub 2}Zr{sub 2}O{sub 7} grains present within the regular-shaped regions are polycrystalline, whereas those present in the surrounding are epitaxial. Some polycrystalline regions ranging from several micrometers to several tens of micrometers grew across the NiW grain boundaries underneath. To understand this phenomenon, the properties of the precursors and corresponding xerogel were studied by Fourier transform infrared spectroscopy and coupled thermogravimetry/differential thermal analysis. The results showed that both the solutions mainly contain small Gd−Zr−O clusters obtained by the reaction of zirconium acetylacetonate with propionic acid during the precursor synthesis. The regular-shaped regions were probably formed by large Gd−Zr−O frameworks with a metastable structure in the solution with limited aging time. This study demonstrates the importance of the precise control of chemical reaction path to enhance the stability and homogeneity of the precursors of the CSD route. - Highlights: •We investigate microstructure

  15. Dirichlet topological defects

    International Nuclear Information System (INIS)

    Carroll, S.M.; Trodden, M.

    1998-01-01

    We propose a class of field theories featuring solitonic solutions in which topological defects can end when they intersect other defects of equal or higher dimensionality. Such configurations may be termed open-quotes Dirichlet topological defects,close quotes in analogy with the D-branes of string theory. Our discussion focuses on defects in scalar field theories with either gauge or global symmetries, in 3+1 dimensions; the types of defects considered include walls ending on walls, strings on walls, and strings on strings. copyright 1998 The American Physical Society

  16. Synthetic Defects for Vibrothermography

    Science.gov (United States)

    Renshaw, Jeremy; Holland, Stephen D.; Thompson, R. Bruce; Eisenmann, David J.

    2010-02-01

    Synthetic defects are an important tool used for characterizing the performance of nondestructive evaluation techniques. Viscous material-filled synthetic defects were developed for use in vibrothermography (also known as sonic IR) as a tool to improve inspection accuracy and reliability. This paper describes how the heat-generation response of these VMF synthetic defects is similar to the response of real defects. It also shows how VMF defects can be applied to improve inspection accuracy for complex industrial parts and presents a study of their application in an aircraft engine stator vane.

  17. Defect production in ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J. [Oak Ridge National Lab., TN (United States); Kinoshita, C. [Kyushu Univ. (Japan)

    1997-08-01

    A review is given of several important defect production and accumulation parameters for irradiated ceramics. Materials covered in this review include alumina, magnesia, spinel silicon carbide, silicon nitride, aluminum nitride and diamond. Whereas threshold displacement energies for many ceramics are known within a reasonable level of uncertainty (with notable exceptions being AIN and Si{sub 3}N{sub 4}), relatively little information exists on the equally important parameters of surviving defect fraction (defect production efficiency) and point defect migration energies for most ceramics. Very little fundamental displacement damage information is available for nitride ceramics. The role of subthreshold irradiation on defect migration and microstructural evolution is also briefly discussed.

  18. On holographic defect entropy

    International Nuclear Information System (INIS)

    Estes, John; Jensen, Kristan; O’Bannon, Andy; Tsatis, Efstratios; Wrase, Timm

    2014-01-01

    We study a number of (3+1)- and (2+1)-dimensional defect and boundary conformal field theories holographically dual to supergravity theories. In all cases the defects or boundaries are planar, and the defects are codimension-one. Using holography, we compute the entanglement entropy of a (hemi-)spherical region centered on the defect (boundary). We define defect and boundary entropies from the entanglement entropy by an appropriate background subtraction. For some (3+1)-dimensional theories we find evidence that the defect/boundary entropy changes monotonically under certain renormalization group flows triggered by operators localized at the defect or boundary. This provides evidence that the g-theorem of (1+1)-dimensional field theories generalizes to higher dimensions

  19. Genital and Urinary Tract Defects

    Science.gov (United States)

    ... conditions > Genital and urinary tract defects Genital and urinary tract defects E-mail to a friend Please fill ... and extra fluids. What problems can genital and urinary tract defects cause? Genital and urinary tract defects affect ...

  20. Detection and defect correction of operating process

    International Nuclear Information System (INIS)

    Vasendina, Elena; Plotnikova, Inna; Levitskaya, Anastasiya; Kvesko, Svetlana

    2016-01-01

    The article is devoted to the current problem of enterprise competitiveness rise in hard and competitive terms of business environment. The importance of modern equipment for detection of defects and their correction is explained. Production of chipboard is used as an object of research. Short description and main results of estimation efficiency of innovative solutions of enterprises are considered. (paper)

  1. Idiopathic short stature

    Directory of Open Access Journals (Sweden)

    Vlaški Jovan

    2013-01-01

    Full Text Available Growth is a complex process and the basic characteristic of child- hood growth monitoring provides insight into the physiological and pathological events in the body. Statistically, the short stature means departure from the values of height for age and sex (in a particular environment, which is below -2 standard deviation score, or less than -2 standard deviation, i.e. below the third percentile. Advances in molecular genetics have contributed to the improvement of diagnostics in endocrinology. Analysis of patients’ genotypes should not be performed before taking a classical history, detailed clinical examination and appropriate tests. In patients with idiopathic short stature specific causes are excluded, such as growth hormone deficiency, Turner syndrome, short stature due to low birth weight, intrauterine growth retardation, small for gestational age, dysmorphology syndromes and chronic childhood diseases. The exclusion of abovementioned conditions leaves a large number of children with short stature whose etiology includes patients with genetic short stature or familial short stature and those who are low in relation to genetic potential, and who could also have some unrecognized endocrine defect. Idiopathic short stature represents a short stature of unknown cause of heterogeneous etiology, and is characterized by a normal response of growth hormone during stimulation tests (>10 ng/ml or 20 mJ/l, without other disorders, of normal body mass and length at birth. In idiopathic short stature standard deviation score rates <-2.25 (-2 to -3 or <1.2 percentile. These are also criteria for the initiation of growth hormone therapy. In children with short stature there is also the presence of psychological and social suffering. Goals of treatment with growth hormone involve achieving normal height and normal growth rate during childhood.

  2. Computer experiment studies on mechanisms for irradiation induced defect production and annealing processes. Final report

    International Nuclear Information System (INIS)

    Beeler, J.R. Jr.; Beeler, M.F.

    1979-06-01

    This research is based on pair potentials used in the Brookhaven work. It extends their use in defect production simulations to the 5 MeV range and characterizes the short term annealing of the primary defect states. Defect properties and interactions are studied. Defect interactions include carbon, helium, and misfit metallic substitutional impurity interactions with vacancy and interstitial defects as well as vacancy-vacancy, interstitial-interstitial and vacancy-interstitial interactions

  3. Computer experiment studies on mechanisms for irradiation induced defect production and annealing processes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Beeler, J.R. Jr.; Beeler, M.F.

    1979-06-01

    This research is based on pair potentials used in the Brookhaven work. It extends their use in defect production simulations to the 5 MeV range and characterizes the short term annealing of the primary defect states. Defect properties and interactions are studied. Defect interactions include carbon, helium, and misfit metallic substitutional impurity interactions with vacancy and interstitial defects as well as vacancy-vacancy, interstitial-interstitial and vacancy-interstitial interactions. (FS)

  4. Highly visible-light luminescence properties of the carboxyl-functionalized short and ultrashort MWNTs

    International Nuclear Information System (INIS)

    Luo Yongsong; Xia Xiaohong; Liang Ying; Zhang Yonggang; Ren Qinfeng; Li Jialin; Jia Zhijie; Tang Yiwen

    2007-01-01

    Luminescence of the short multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups has been studied. The results show that the carboxyl-functionalized short MWNTs could emit luminescence and the emission peak appears at 500 nm with a corresponding optimal excitation wavelength centering at 310 nm. When the short MWNTs are filtered through 0.15 μm polytetrafluoroethylene (PTFE) membrane, the ultrashort MWNTs are obtained from the filtrate. An interesting feature for the ultrashort MWNTs is that the emission intensity is strengthened and the peak is slightly blue shifted to 460 nm. This result indicates that the luminescence properties of MWNTs are strongly affected by the tube length. After chemical oxidization cutting, defects and carboxylic acid groups at the tube end and/or sidewall can be produced; the more shorten of MWNTs, the better dispersion and carboxylic passivation of the nanotubes, and the more intense luminescence emissions. The broad emissions are logically attributed to the trapping of excitation energy by defect sites in the carboxyl-functionalized nanotube structure. - Graphical abstract: Luminescence of the short and ultrashort multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups, which is logically attributed to the trapping of excitation energy by defect sites, has been studied

  5. Radiation defects in some oxide compounds

    International Nuclear Information System (INIS)

    Kaczmarek, S.M.

    1999-01-01

    Yttrium aluminium garnets, yttrium aluminium perovskite, strontium and barium lanthanum and gadolinium gallates, lithium niobate and tantalate as-grown crystals and doped by diffusion with rare-earth (Nd, Dy, Er, Tm, Ho, Pr, Ce, Eu) and ions of the first transition series (Mn, Cr, Cu, Fe) were investigated optically and using electron spin resonance method before and after gamma, electron and proton irradiation. (author)

  6. PREFACE: The International Workshop on Positron Studies of Defects 2014

    Science.gov (United States)

    Sugita, Kazuki; Shirai, Yasuharu

    2016-01-01

    The International Workshop on Positron Studies of Defects 2014 (PSD-14) was held in Kyoto, Japan from 14-19 September, 2014. The PSD Workshop brought together positron scientists interested in studying defects to an international platform for presenting and discussing recent results and achievements, including new experimental and theoretical methods in the field. The workshop topics can be characterized as follows: • Positron studies of defects in semiconductors and oxides • Positron studies of defects in metals • New experimental methods and equipment • Theoretical calculations and simulations of momentum distributions, positron lifetimes and other characteristics for defects • Positron studies of defects in combination with complementary methods • Positron beam studies of defects at surfaces, interfaces, in sub-surface regions and thin films • Nanostructures and amorphous materials

  7. Influence of agglomeration of cerium oxide nanoparticles and speciation of cerium(III) on short term effects to the green algae Chlamydomonas reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Röhder, Lena A. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); ETH-Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich 8092 (Switzerland); Brandt, Tanja [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); Sigg, Laura [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); ETH-Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich 8092 (Switzerland); Behra, Renata, E-mail: Renata.behra@eawag.ch [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland)

    2014-07-01

    Highlights: • Phosphate-dispersed CeO₂ NP did not affect photosynthetic yield in C. reinhardtii. • Agglomerated CeO₂ NP slightly decreased photosynthetic yield. • Cerium(III) was shown to affect photosynthetic yield and intracellular ROS level. • Slight effects of CeO₂ NP were caused by dissolved Ce³⁺ ions present in suspensions. • Wild type and cell wall free mutant of C. reinhardtii showed the same sensitivity. - Abstract: Cerium oxide nanoparticles (CeO₂ NP) are increasingly used in industrial applications and may be released to the aquatic environment. The fate of CeO₂ NP and effects on algae are largely unknown. In this study, the short term effects of CeO₂ NP in two different agglomeration states on the green algae Chlamydomonas reinhardtii were examined. The role of dissolved cerium(III) on toxicity, its speciation and the dissolution of CeO₂ NP were considered. The role of cell wall of C. reinhardtii as a barrier and its influence on the sensitivity to CeO₂ NP and cerium(III) was evaluated by testing both, the wild type and the cell wall free mutant of C. reinhardtii. Characterization showed that CeO₂ NP had a surface charge of ~0 mV at physiological pH and agglomerated in exposure media. Phosphate stabilized CeO₂ NP at pH 7.5 over 24 h. This effect was exploited to test CeO₂ NP dispersed in phosphate with a mean size of 140 nm and agglomerated in absence of phosphate with a mean size of 2000 nm. The level of dissolved cerium(III) in CeO₂ NP suspensions was very low and between 0.1 and 27 nM in all tested media. Exposure of C. reinhardtii to Ce(NO₃)₃ decreased the photosynthetic yield in a concentration dependent manner with EC₅₀ of 7.5 ± 0.84 μM for wild type and EC₅₀ of 6.3 ± 0.53 μM for the cell wall free mutant. The intracellular level of reactive oxygen species (ROS) increased upon exposure to Ce(NO₃)₃ with effective concentrations similar to those inhibiting photosynthesis. The agglomerated Ce

  8. Short philtrum

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003302.htm Short philtrum To use the sharing features on this page, please enable JavaScript. A short philtrum is a shorter than normal distance between ...

  9. Electrically Rotatable Polarizer Using One-Dimensional Photonic Crystal with a Nematic Liquid Crystal Defect Layer

    Directory of Open Access Journals (Sweden)

    Ryotaro Ozaki

    2015-09-01

    Full Text Available Polarization characteristics of defect mode peaks in a one-dimensional (1D photonic crystal (PC with a nematic liquid crystal (NLC defect layer have been investigated. Two different polarized defect modes are observed in a stop band. One group of defect modes is polarized along the long molecular axis of the NLC, whereas another group is polarized along its short axis. Polarizations of the defect modes can be tuned by field-induced in-plane reorientation of the NLC in the defect layer. The polarization properties of the 1D PC with the NLC defect layer is also investigated by the finite difference time domain (FDTD simulation.

  10. Short-term anoxic conditioning hormesis boosts antioxidant defenses, lowers oxidative damage following irradiation and enhances male sexual performance in the Caribbean fruit fly, Anastrepha suspensa

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Martinez, Giancarlo; Hahn, Daniel A [Department of Entomology and Nematology, University of Florida, Gainesville, FL (United States)

    2013-01-15

    Most organisms are repeatedly exposed to oxidative stress from multiple sources throughout their lifetimes, potentially affecting all aspects of organismal performance. Here we test whether exposure to a conditioning bout of anoxia early in adulthood induces a hormetic response that confers resistance to oxidative stress and enhances male sexual performance later in life in the Caribbean fruit fly, Anastrepha suspensa. Anoxic conditioning of adults prior to emergence led to an increase in antioxidant capacity driven by mitochondrial superoxide dismutase and glutathione peroxidase. When exposed to gamma irradiation, a strong oxidative stressor, males that received anoxic conditioning had lower lipid and protein oxidative damage at sexual maturity. Anoxia conditioning led to greater male sexual competitiveness compared with unconditioned males when both were irradiated, although there was no effect of anoxia conditioning on mating competitiveness in unirradiated males. Anoxia also led to higher adult emergence rates and greater flight ability in irradiation-stressed flies while preserving steriity. Thus, hormetic treatments that increased antioxidant enzyme activity also improved male performance after irradiation, suggesting that antioxidant enzymes play an important role in mediating the relationship between oxidative stress and sexual selection. Furthermore, our work has important applied implications for the sterile insect technique (SIT), an environmentally friendly method of insect pest control where males are sterilized by irradiation and deployed in the field to disrupt pest populations via mating. We suggest that hormetic treatments specifically designed to enhance antioxidant activity may produce more sexually competitive sterile males, thus improving the efficacy and economy of SIT programs. (author)

  11. Short-term beef consumption promotes systemic oxidative stress, TMAO formation and inflammation in rats, and dietary fat content modulates these effects.

    Science.gov (United States)

    Van Hecke, Thomas; Jakobsen, Louise M A; Vossen, Els; Guéraud, Françoise; De Vos, Filip; Pierre, Fabrice; Bertram, Hanne C S; De Smet, Stefaan

    2016-09-14

    A high consumption of red and/or processed meat is associated with a higher risk to develop several chronic diseases in which oxidative stress, trimethylamine-N-oxide (TMAO) and/or inflammation are involved. We aimed to elucidate the effect of white (chicken) vs. red (beef) meat consumption in a low vs. high dietary fat context (2 × 2 factorial design) on oxidative stress, TMAO and inflammation in Sprague-Dawley rats. Higher malondialdehyde (MDA) concentrations were found in gastrointestinal contents (up to 96% higher) and colonic tissues (+8.8%) of rats fed the beef diets (all P stress, TMAO formation and inflammation, depending on the dietary fat content and composition.

  12. Short-term starvation is a strategy to unravel the cellular capacity of oxidizing specific exogenous/endogenous substrates in mitochondria.

    Science.gov (United States)

    Zeidler, Julianna D; Fernandes-Siqueira, Lorena O; Carvalho, Ana S; Cararo-Lopes, Eduardo; Dias, Matheus H; Ketzer, Luisa A; Galina, Antonio; Da Poian, Andrea T

    2017-08-25

    Mitochondrial oxidation of nutrients is tightly regulated in response to the cellular environment and changes in energy demands. In vitro studies evaluating the mitochondrial capacity of oxidizing different substrates are important for understanding metabolic shifts in physiological adaptations and pathological conditions, but may be influenced by the nutrients present in the culture medium or by the utilization of endogenous stores. One such influence is exemplified by the Crabtree effect (the glucose-mediated inhibition of mitochondrial respiration) as most in vitro experiments are performed in glucose-containing media. Here, using high-resolution respirometry, we evaluated the oxidation of endogenous or exogenous substrates by cell lines harboring different metabolic profiles. We found that a 1-h deprivation of the main energetic nutrients is an appropriate strategy to abolish interference of endogenous or undesirable exogenous substrates with the cellular capacity of oxidizing specific substrates, namely glutamine, pyruvate, glucose, or palmitate, in mitochondria. This approach primed mitochondria to immediately increase their oxygen consumption after the addition of the exogenous nutrients. All starved cells could oxidize exogenous glutamine, whereas the capacity for oxidizing palmitate was limited to human hepatocarcinoma Huh7 cells and to C2C12 mouse myoblasts that differentiated into myotubes. In the presence of exogenous glucose, starvation decreased the Crabtree effect in Huh7 and C2C12 cells and abrogated it in mouse neuroblastoma N2A cells. Interestingly, the fact that the Crabtree effect was observed only for mitochondrial basal respiration but not for the maximum respiratory capacity suggests it is not caused by a direct effect on the electron transport system. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Metallography of defects

    International Nuclear Information System (INIS)

    Borisova, E.A.; Bochvar, G.A.; Brun, M.Ya.

    1980-01-01

    Different types of defects of metallurgical, technological and exploitation origin in intermediate and final products of titanium alloys, are considered. The examples of metallic and nonmetallic inclusions, chemical homogeneity, different grains, bands, cracks, places of searing, porosity are given; methods of detecting the above defects are described. The methods of metallography, X-ray spectral analysis, measuring microhardness are used

  14. Beating Birth Defects

    Centers for Disease Control (CDC) Podcasts

    Each year in the U.S., one in 33 babies is affected by a major birth defect. Women can greatly improve their chances of giving birth to a healthy baby by avoiding some of the risk factors for birth defects before and during pregnancy. In this podcast, Dr. Stuart Shapira discusses ways to improve the chances of giving birth to a healthy baby.

  15. Short Communication on “Coarsening of Y-rich oxide particles in 9%Cr-ODS Eurofer steel annealed at 1350 °C”

    Energy Technology Data Exchange (ETDEWEB)

    Sandim, M.J.R.; Souza Filho, I.R.; Bredda, E.H. [Lorena School of Engineering, University of Sao Paulo, 12602-810, Lorena (Brazil); Kostka, A.; Raabe, D. [Max-Planck-Institut für Eisenforschung, D-40237, Düsseldorf (Germany); Sandim, H.R.Z., E-mail: hsandim@demar.eel.usp.br [Lorena School of Engineering, University of Sao Paulo, 12602-810, Lorena (Brazil)

    2017-02-15

    Oxide-dispersion strengthened (ODS) Eurofer steel is targeted for structural applications in future fusion nuclear reactors. Samples were cold rolled down to 80% reduction in thickness and annealed at 1350 °C up to 8 h. The microstructural characterization was performed using Vickers microhardness testing, electron backscatter diffraction, scanning and scanning transmission electron microscopies. Experimental results provide evidence of coarsening of the Y-rich oxide particles in ODS-Eurofer steel annealed at 1350 °C within delta ferrite phase field.

  16. Topological defect clustering and plastic deformation mechanisms in functionalized graphene

    Science.gov (United States)

    Nunes, Ricardo; Araujo, Joice; Chacham, Helio

    2011-03-01

    We present ab initio results suggesting that strain plays a central role in the clustering of topological defects in strained and functionalized graphene models. We apply strain onto the topological-defect graphene networks from our previous work, and obtain topological-defect clustering patterns which are in excellent agreement with recent observations in samples of reduced graphene oxide. In our models, the graphene layer, containing an initial concentration of isolated topological defects, is covered by hydrogen or hydroxyl groups. Our results also suggest a rich variety of plastic deformation mechanism in functionalized graphene systems. We acknowledge support from the Brazilian agencies: CNPq, Fapemig, and INCT-Materiais de Carbono.

  17. Defects in dilute nitrides

    International Nuclear Information System (INIS)

    Chen, W.M.; Buyanova, I.A.; Tu, C.W.; Yonezu, H.

    2005-01-01

    We provide a brief review our recent results from optically detected magnetic resonance studies of grown-in non-radiative defects in dilute nitrides, i.e. Ga(In)NAs and Ga(Al,In)NP. Defect complexes involving intrinsic defects such as As Ga antisites and Ga i self interstitials were positively identified.Effects of growth conditions, chemical compositions and post-growth treatments on formation of the defects are closely examined. These grown-in defects are shown to play an important role in non-radiative carrier recombination and thus in degrading optical quality of the alloys, harmful to performance of potential optoelectronic and photonic devices based on these dilute nitrides. (author)

  18. Modeling of extended defects in silicon

    International Nuclear Information System (INIS)

    Law, M.E.; Jones, K.S.; Earles, S.K.; Lilak, A.D.; Xu, J.W.

    1997-01-01

    Transient Enhanced Diffusion (TED) is one of the biggest modeling challenges present in predicting scaled technologies. Damage from implantation of dopant ions changes the diffusivities of the dopants and precipitates to form complex extended defects. Developing a quantitative model for the extended defect behavior during short time, low temperature anneals is a key to explaining TED. This paper reviews some of the modeling developments over the last several years, and discusses some of the challenges that remain to be addressed. Two examples of models compared to experimental work are presented and discussed

  19. Short-term exposure to benzo[a]pyrene causes oxidative damage and affects haemolymph steroid levels in female crab Portunus trituberculatus

    International Nuclear Information System (INIS)

    Wen, Jianmin; Pan, Luqing

    2016-01-01

    Concern has increased regarding the adverse effects of polycyclic aromatic hydrocarbons (PAHs) on reproduction. However, limited information is available on the effects of PAHs in crustacean. In order to determine whether benzo[a]pyrene (B[a]P) could cause reproductive toxicity on the swimming crab Portunus trituberculatus, sexually mature female crabs were exposed to environmentally relevant concentrations of B[a]P (0, 0.1, 0.5 and 2.5 μg/L) for 10 days. B[a]P treatments resulted in high accumulation in ovary, and induced oxidative stress in a dose-dependent manner on ovary of crab. Furthermore, the haemolymph estradiol (E_2) and testosterone (T) levels were significantly decreased. Histological investigation also revealed the reproductive toxicity caused by B[a]P. The results demonstrated that waterborne exposure to B[a]P caused oxidative damage and disrupted sex steroids in female crab P. trituberculatus, ultimately resulting in histological alternation. - Highlights: • Waterborne exposure to B[a]P resulted in high accumulation in crab ovary. • The haemolymph 17β-estradiol and testosterone levels were significantly decreased by B[a]P exposure. • B[a]P induced oxidative damage in crab ovary. • B[a]P exposure caused histopathological alterations in crab ovary. - B[a]P disrupted sex steroids, caused oxidative damage and histological alternation in female crab P. trituberculatus.

  20. A short-term intervention trial with selenate, selenium-enriched yeast and selenium-enriched milk: effects on oxidative defence regulation

    DEFF Research Database (Denmark)

    Ravn-Haren, Gitte; Bugel, Susanne; Krath, Britta

    2008-01-01

    -enriched yeast or Se-enriched milk. We found no effect on plasma lipid resistance to oxidation, total cholesterol, TAG, HDL- and LDL-cholesterol, GPX, glutathione reductase (GR) and glutathione S-transferase (GST) activities measured in erythrocytes, GPX and GR activities determined in plasma, or GR and GST...

  1. Formation of topological defects

    International Nuclear Information System (INIS)

    Vachaspati, T.

    1991-01-01

    We consider the formation of point and line topological defects (monopoles and strings) from a general point of view by allowing the probability of formation of a defect to vary. To investigate the statistical properties of the defects at formation we give qualitative arguments that are independent of any particular model in which such defects occur. These arguments are substantiated by numerical results in the case of strings and for monopoles in two dimensions. We find that the network of strings at formation undergoes a transition at a certain critical density below which there are no infinite strings and the closed-string (loop) distribution is exponentially suppressed at large lengths. The results are contrasted with the results of statistical arguments applied to a box of strings in dynamical equilibrium. We argue that if point defects were to form with smaller probability, the distance between monopoles and antimonopoles would decrease while the monopole-to-monopole distance would increase. We find that monopoles are always paired with antimonopoles but the pairing becomes clean only when the number density of defects is small. A similar reasoning would also apply to other defects

  2. The control of short-term feed intake by metabolic oxidation in late-pregnant and early lactating dairy cows exposed to high ambient temperatures.

    Science.gov (United States)

    Eslamizad, Mehdi; Lamp, Ole; Derno, Michael; Kuhla, Björn

    2015-06-01

    The objective of the present study was to integrate the dynamics of feed intake and metabolic oxidation in late pregnant and early lactating Holstein cows under heat stress conditions. On day 21 before parturition and again on day 20 after parturition, seven Holstein cows were kept for 7days at thermoneutral (TN) conditions (15°C; temperature-humidity-index (THI)=60) followed by a 7day heat stress (HS) period at 28°C (THI=76). On the last day of each temperature condition, gas exchange, feed intake and water intake were recorded every 6min in a respiration chamber. Pre- and post-partum cows responded to HS by decreasing feed intake. The reduction in feed intake in pre-partum cows was achieved through decreased meal size, meal duration, eating rate and daily eating time with no change in meal frequency, while post-partum cows kept under HS conditions showed variable responses in feeding behavior. In both pre- and post-partum cows exposed to heat stress, daily and resting metabolic heat production decreased while the periprandial respiratory quotient (RQ) increased. The prolonged time between meal and the postprandial minimum in fat oxidation and the postprandial RQ maximum, respectively, revealed that HS as compared to TN early-lactating cows have slower postprandial fat oxidation, longer feed digestion, and thereby showing a shift from fat to glucose utilization. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Point defects and defect clusters examined on the basis of some fundamental experiments

    International Nuclear Information System (INIS)

    Zuppiroli, L.

    1975-01-01

    On progressing from the centre of the defect to the surface the theoretical approach to a point defect passes from electronic theories to elastic theory. Experiments by which the point defect can be observed fall into two categories. Those which detect long-range effects: measurement of dimensional variations in the sample; measurement of the mean crystal parameter variation; elastic X-ray scattering near the nodes of the reciprocal lattice (Huang scattering). Those which detect more local effects: low-temperature resistivity measurement; positron capture and annihilation; local scattering far from the reciprocal lattice nodes. Experiments involving both short and long-range effects can always be found. This is the case for example with the dechanneling of α particles by defects. Certain of the experimental methods quoted above apply also to the study of point defect clusters. These methods are illustrated by some of their most striking results which over the last twenty years have refined our knowledge of point defects and defect clusters: length and crystal parameter measurements; diffuse X-ray scattering; low-temperature resistivity measurements; ion emission microscopy; electron microscopy; elastoresistivity [fr

  4. Solid oxide fuel cell short stack performance testing - Part A: Experimental analysis and μ-combined heat and power unit comparison

    Science.gov (United States)

    Mastropasqua, L.; Campanari, S.; Brouwer, J.

    2017-12-01

    The need to experimentally understand the detailed performance of SOFC stacks under operating conditions typical of commercial SOFC systems has prompted this two-part study. The steady state performance of a 6-cell short stack of yttria (Y2O3) stabilised zirconia (YSZ) with Ni/YSZ anodes and composite Sr-doped lanthanum manganite (LaMnO3, LSM)/YSZ cathodes is experimentally evaluated. In Part A, the stack characterisation is carried out by means of sensitivity analyses on the fuel utilisation factor and the steam-to-carbon ratio. Electrical and environmental performances are assessed and the results are compared with a commercial full-scale micro-CHP system, which comprises the same cells. The results show that the measured temperature dynamics of the short stack in a test stand environment are on the order of many minutes; therefore, one cannot neglect temperature dynamics for a precise measurement of the steady state polarisation behaviour. The overall polarisation performance is comparable to that of the full stack employed in the micro-CHP system, confirming the good representation that short-stack analyses can give of the entire SOFC module. The environmental performance is measured verifying the negligible values of NO emissions (<10 ppb) across the whole polarisation curve.

  5. Ventricular Septal Defect (VSD)

    Science.gov (United States)

    ... Call your doctor if your baby or child: Tires easily when eating or playing Is not gaining ... heart procedures. Risk factors Ventricular septal defects may run in families and sometimes may occur with other ...

  6. Birth Defects: Cerebral Palsy

    Science.gov (United States)

    ... Loss > Birth defects & other health conditions > Cerebral palsy Cerebral palsy E-mail to a friend Please fill in ... this page It's been added to your dashboard . Cerebral palsy (also called CP) is a group of conditions ...

  7. Endocardial cushion defect

    Science.gov (United States)

    ... Philadelphia, PA: Elsevier; 2016:chap 426. Kouchoukos NT, Blackstone EH, Hanley FL, Kirklin JK. Atrioventricular septal defect. In: Kouchoukos NT, Blackstone EH, Hanley FL, Kirklin JK, eds. Kirklin/Barratt- ...

  8. Repairing Nanoparticle Surface Defects

    NARCIS (Netherlands)

    Marino, Emanuele; Kodger, Thomas E.; Crisp, R.W.; Timmerman, Dolf; MacArthur, Katherine E.; Heggen, Marc; Schall, Peter

    2017-01-01

    Solar devices based on semiconductor nanoparticles require the use of conductive ligands; however, replacing the native, insulating ligands with conductive metal chalcogenide complexes introduces structural defects within the crystalline nanostructure that act as traps for charge carriers. We

  9. Point defects in platinum

    International Nuclear Information System (INIS)

    Piercy, G.R.

    1960-01-01

    An investigation was made of the mobility and types of point defect introduced in platinum by deformation in liquid nitrogen, quenching into water from 1600 o C, or reactor irradiation at 50 o C. In all cases the activation energy for motion of the defect was determined from measurements of electrical resistivity. Measurements of density, hardness, and x-ray line broadening were also made there applicable. These experiments indicated that the principal defects remaining in platinum after irradiation were single vacant lattice sites and after quenching were pairs of vacant lattice sites. Those present after deformation In liquid nitrogen were single vacant lattice sites and another type of defect, perhaps interstitial atoms. (author)

  10. Systematic Study of the PbWO4 Crystal Short Term Instalibity Under Irradiation

    CERN Document Server

    Annenkov, Alexander; Chipaux, Rémi; Drobychev, Gleb; Fedorov, Andrey; Géléoc, Marie; Golubev, Nikolai; Korzhik, Mikhail; Lecoq, Paul; Ligun, A B; Missevitch, Oleg; Pavlenko, V B; Peigneux, Jean-Pierre; Singovsky, Alexander

    1997-01-01

    The effect of the irradiation on the lead tungstate ( PWO) scintillator properties has been studied at different irradiation facilities. Lead tungstate crystals grown with the tuning of oxides content in the melt to the stoichiometry of pure sheelite or sheelite-like type crystals and doped with heterovalent, trivalent and pentavalent impurities have been studied in order to optimize their resistance to irradiation. A combination of a selective cleaning of raw materials, a tuning of the melt from crystallization to crystallisation, and a destruction or compensation of the point structure defects has been used to minimize the short-term instability of PWO parameters under irradiation.

  11. New fundamental defects in a-SiO2

    International Nuclear Information System (INIS)

    Karna, S.P.; Kurtz, H.A.; Shedd, W.M.; Pugh, R.D.; Singaraju, B.K.

    1999-01-01

    Throughout the three decades of research into radiation-induced degradation of metal-oxide-semiconductor (MOS) devices, investigators understood that point defects in the Si-SiO 2 structure (localized deviations from stoichiometrically pure Si and SiO 2 ) are responsible for many observed anomalies. Basic research in this area has progressed along two tracks: (i) differentiating the anomalies based upon subtle differences in their characteristic behavior, and (ii) precise description of the defects responsible for the anomalous behavior. These two research tracks are complementary since often a discovery in one area provides insight and ultimately leads to discoveries in the other. Here, the atomic structure and spin properties of two previously undescribed amorphous silicon dioxide fundamental point defects have been characterized for the first time by ab initio quantum mechanical calculations. Both defects are electrically neutral trivalent silicon centers in the oxide. One of the defects, the X-center, is determined to have an O 2 Sitriple b ondSi ↑ atomic structure. The other defect, called the Y-center, is found to have an OSi 2 triple b ondSi ↑ structure. Calculated electronic and electrical properties of the new defect centers are consistent with the published characteristics of the oxide switching trap or border trap precursors

  12. Molecular dynamics simulation on the formation and annihilation behaviors of radiation defects in Li2O

    International Nuclear Information System (INIS)

    Takuji Oda; Satoru Tanaka; Yasuhisa Oya

    2006-01-01

    The influence of radiation defects is one of the main factors that determine tritium release behavior from blanket breeding materials in fusion reactors. Classical molecular dynamics simulation (MD) is a powerful technique to investigate the radiation damage processes, because it can provide atomic-scale information on the defects. In this study, we conducted radiation simulation for Li 2 O using MD and analyzed formation and annihilation behaviors of radiation defects, as a fundamental research for radiation response of Li-containing oxides. Buckingham type two-body potential model was used. In order to remove the unphysical impulsive force at short inter-ionic distances in Buckingham model, each potential function was connected to that of the ZBL potential models at around 0.8 A. NEV ensemble was employed with the initial simulation temperature of 0 K. 10 x 10 x 10 supercell consisting of 4000 Li 2 O was used as a unit cell under 3D periodic boundary conditions. Radiation simulation was initiated by introducing an energy of a certain direction to an ion, as a displacement energy. The lowest displacement energy by which a defect was created and survived beyond 5 ps was regarded as the threshold energy. 42 and 21 displacement directions were surveyed for Li and O, respectively, based on the symmetry of the Li 2 O crystal. In both Li and O defect formations, [100] displacement shows significantly lower threshold energy than [111] displacement. Li defects were easily created than O defects almost in all directions. In fact, the average threshold energy except [111] displacement, which possesses extremely high threshold energy, was 21 eV for Li and 49 eV for O. In some cases, no defect could survive beyond 5 ps even by higher displacement energies than the threshold energy, due to the self-annealing effect. The self-annealing completed basically within 1 ps after introduction of displacement energy. At around this time, velocity distribution of all ions in the system

  13. Effect of Short-term Quercetin, Caloric Restriction and Combined Treatment on Age-related Oxidative Stress Markers in the Rat Cerebral Cortex

    Science.gov (United States)

    Alugoju, Phaniendra; Swamy, Vkd Krishan; Periyasamy, Latha

    2018-03-14

    Aging is characterized by gradual accumulation of macromolecular damage leading to progressive loss of physiological function and increased susceptibility to diverse diseases. Effective anti-aging strategies involving caloric restriction or antioxidant supplementation are receiving growing attention to attenuate macromolecular damage in age associated pathology. In the present study, we for the first time investigated the effect of quercetin, caloric restriction and combined treatment (caloric restriction with quercetin) on oxidative stress parameters, acetylcholinesterase and ATPases enzyme activities in the cerebral cortex of aged male Wistar rats. 21 months aged rats were divided into four groups (n=6-8) such as group 1-fed ad libitum (AL); group 2-quercetin supplementation of 50 mg/kg b.w/day for 45 days fed ad libitum (QUER); group 3: caloric restricted (CR) (fed 40% reduced AL for 45 days); group 4-fed 40% CR and 50 mg/kg b.w/day QUER for 45 days (CR + QUER). Group 5-three month age old rats served as young control (YOUNG). Our results demonstrate that combined treatment of caloric restriction and quercetin significantly improved the age associated decline in the activities of endogenous antioxidant enzymes [such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)] and glutathione (GSH) content and attenuated elevated levels of protein carbonyl content (PCC), lipid peroxidation, lipofuscin, reactive oxygen species (ROS), and nitric oxide (NO). Furthermore, it is also observed that combined treatment ameliorated age associated alterations in acetylcholine esterase (AChE) and adenosine triphosphatases (ATPases) such as Na+/K+-ATPase and Ca+2-ATPase (but not Mg+2- ATPase) enzyme activities. Finally, we conclude that combined treatment of caloric restriction and quercetin (but not either treatment alone) in late life is an effective anti-aging therapy to counteract the age related accumulation of oxidative macromolecular damage

  14. Short communication

    African Journals Online (AJOL)

    abp

    2017-09-04

    Sep 4, 2017 ... Face-to-face interviews were conducted using a standardized ... Short communication. Open Access ... clinic during the time of the study and were invited to participate in the study. .... consume them. This is another ...

  15. SHORT COMMUNICATION

    African Journals Online (AJOL)

    PROF P.T. KAYE

    . SHORT COMMUNICATION. Formation and Structural Analysis of Novel Dibornyl Ethers. Perry T. Kaye*, Andrew R. Duggan, Joseph M. Matjila, Warner E. Molema, and. Swarnam S. Ravindran. Department of Chemistry, Rhodes University, Grahamstown, ...

  16. Dry corrosion prediction of radioactive waste containers in long term interim storage: mechanisms of low temperature oxidation of pure iron and numerical simulation of an oxide scale growth

    International Nuclear Information System (INIS)

    Bertrand, N.

    2006-10-01

    In the framework of research on long term behaviour of radioactive waste containers, this work consists on the one hand in the study of low temperature oxidation of iron and on the other hand in the development of a numerical model of oxide scale growth. Isothermal oxidation experiments are performed on pure iron at 300 and 400 C in dry and humid air at atmospheric pressure. Oxide scales formed in these conditions are characterized. They are composed of a duplex magnetite scale under a thin hematite scale. The inner layer of the duplex scale is thinner than the outer one. Both are composed of columnar grains, that are smaller in the inner part. The outer hematite layer is made of very small equiaxed grains. Markers and tracers experiments show that a part of the scale grows at metal/oxide interface thanks to short-circuits diffusion of oxygen. A model for iron oxide scale growth at low temperature is then deduced. Besides this experimental study, the numerical model EKINOX (Estimation Kinetics Oxidation) is developed. It allows to simulate the growth of an oxide scale controlled by mixed mechanisms, such as anionic and cationic vacancies diffusion through the scale, as well as metal transfer at metal/oxide interface. It is based on the calculation of concentration profiles of chemical species and also point defects in the oxide scale and in the substrate. This numerical model does not use the classical quasi-steady-state approximation and calculates the future of cationic vacancies at metal/oxide interface. Indeed, these point defects can either be eliminated by interface motion or injected in the substrate, where they can be annihilated, considering sinks as the climb of dislocations. Hence, the influence of substrate cold-work can be investigated. The EKINOX model is validated in the conditions of Wagner's theory and is confronted with experimental results by its application to the case of high temperature oxidation of nickel. (author)

  17. Defect pair formation in fluorine and nitrogen codoped TiO2

    Science.gov (United States)

    Kordatos, A.; Kelaidis, N.; Chroneos, A.

    2018-04-01

    Titanium oxide is extensively investigated because of its high chemical stability and its photocatalytic properties; nevertheless, the large band gap limits its activity to a small portion of the solar spectrum. Nitrogen and fluorine codoping is an efficient defect engineering strategy to increase the photocatalytic activity of titanium oxide. In the present study, we apply density functional theory to investigate the interaction of nitrogen with fluorine and the formation of defect pairs. We show that in fluorine and nitrogen codoped titanium oxide, the FiNi, FONi, and FiNTi defects can form. Their impact on the electronic structure of titanium oxide is discussed.

  18. Norwegian Pitched Roof Defects

    Directory of Open Access Journals (Sweden)

    Lars Gullbrekken

    2016-06-01

    Full Text Available The building constructions investigated in this work are pitched wooden roofs with exterior vertical drainpipes and wooden load-bearing system. The aim of this research is to further investigate the building defects of pitched wooden roofs and obtain an overview of typical roof defects. The work involves an analysis of the building defect archive from the research institute SINTEF Building and Infrastructure. The findings from the SINTEF archive show that moisture is a dominant exposure factor, especially in roof constructions. In pitched wooden roofs, more than half of the defects are caused by deficiencies in design, materials, or workmanship, where these deficiencies allow moisture from precipitation or indoor moisture into the structure. Hence, it is important to increase the focus on robust and durable solutions to avoid defects both from exterior and interior moisture sources in pitched wooden roofs. Proper design of interior ventilation and vapour retarders seem to be the main ways to control entry from interior moisture sources into attic and roof spaces.

  19. Polydispersity-driven topological defects as order-restoring excitations.

    Science.gov (United States)

    Yao, Zhenwei; Olvera de la Cruz, Monica

    2014-04-08

    The engineering of defects in crystalline matter has been extensively exploited to modify the mechanical and electrical properties of many materials. Recent experiments on manipulating extended defects in graphene, for example, show that defects direct the flow of electric charges. The fascinating possibilities offered by defects in two dimensions, known as topological defects, to control material properties provide great motivation to perform fundamental investigations to uncover their role in various systems. Previous studies mostly focus on topological defects in 2D crystals on curved surfaces. On flat geometries, topological defects can be introduced via density inhomogeneities. We investigate here topological defects due to size polydispersity on flat surfaces. Size polydispersity is usually an inevitable feature of a large variety of systems. In this work, simulations show well-organized induced topological defects around an impurity particle of a wrong size. These patterns are not found in systems of identical particles. Our work demonstrates that in polydispersed systems topological defects play the role of restoring order. The simulations show a perfect hexagonal lattice beyond a small defective region around the impurity particle. Elasticity theory has demonstrated an analogy between the elementary topological defects named disclinations to electric charges by associating a charge to a disclination, whose sign depends on the number of its nearest neighbors. Size polydispersity is shown numerically here to be an essential ingredient to understand short-range attractions between like-charge disclinations. Our study suggests that size polydispersity has a promising potential to engineer defects in various systems including nanoparticles and colloidal crystals.

  20. Repairing Nanoparticle Surface Defects.

    Science.gov (United States)

    Marino, Emanuele; Kodger, Thomas E; Crisp, Ryan W; Timmerman, Dolf; MacArthur, Katherine E; Heggen, Marc; Schall, Peter

    2017-10-23

    Solar devices based on semiconductor nanoparticles require the use of conductive ligands; however, replacing the native, insulating ligands with conductive metal chalcogenide complexes introduces structural defects within the crystalline nanostructure that act as traps for charge carriers. We utilized atomically thin semiconductor nanoplatelets as a convenient platform for studying, both microscopically and spectroscopically, the development of defects during ligand exchange with the conductive ligands Na 4 SnS 4 and (NH 4 ) 4 Sn 2 S 6 . These defects can be repaired via mild chemical or thermal routes, through the addition of L-type ligands or wet annealing, respectively. This results in a higher-quality, conductive, colloidally stable nanomaterial that may be used as the active film in optoelectronic devices. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  1. Defect identification using positrons

    International Nuclear Information System (INIS)

    Beling, C.D.; Fung, S.

    2001-01-01

    The current use of the lifetime and Doppler broadening techniques in defect identification is demonstrated with two studies, the first being the identification of carbon vacancy in n-6H SiC through lifetime spectroscopy, and the second the production of de-hydrogenated voids in α-Si:H through light soaking. Some less conventional ideas are presented for more specific defect identification, namely (i) the amalgamation of lifetime and Doppler techniques with conventional deep level transient spectroscopy in what may be called ''positron-deep level transient spectroscopy'', and (ii) the extraction of more spatial information on vacancy defects by means of what may be called ''Fourier transform Doppler broadening of annihilation radiation spectroscopy'' (orig.)

  2. Quantum computing with defects

    Science.gov (United States)

    Varley, Joel

    2011-03-01

    The development of a quantum computer is contingent upon the identification and design of systems for use as qubits, the basic units of quantum information. One of the most promising candidates consists of a defect in diamond known as the nitrogen-vacancy (NV-1) center, since it is an individually-addressable quantum system that can be initialized, manipulated, and measured with high fidelity at room temperature. While the success of the NV-1 stems from its nature as a localized ``deep-center'' point defect, no systematic effort has been made to identify other defects that might behave in a similar way. We provide guidelines for identifying other defect centers with similar properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate systems. To elucidate these points, we compare electronic structure calculations of the NV-1 center in diamond with those of several deep centers in 4H silicon carbide (SiC). Using hybrid functionals, we report formation energies, configuration-coordinate diagrams, and defect-level diagrams to compare and contrast the properties of these defects. We find that the NC VSi - 1 center in SiC, a structural analog of the NV-1 center in diamond, may be a suitable center with very different optical transition energies. We also discuss how the proposed criteria can be translated into guidelines to discover NV analogs in other tetrahedrally coordinated materials. This work was performed in collaboration with J. R. Weber, W. F. Koehl, B. B. Buckley, A. Janotti, C. G. Van de Walle, and D. D. Awschalom. This work was supported by ARO, AFOSR, and NSF.

  3. Defects in semiconductors

    International Nuclear Information System (INIS)

    Pimentel, C.A.F.

    1983-01-01

    Some problems openned in the study of defects in semiconductors are presented. In particular, a review is made of the more important problems in Si monocrystals of basic and technological interest: microdefects and the presence of oxigen and carbon. The techniques usually utilized in the semiconductor material characterization are emphatized according its potentialities. Some applications of x-ray techniques in the epitaxial shell characterization in heterostructures, importants in electronic optics, are shown. The increase in the efficiency of these defect analysis methods in semiconductor materials with the use of synchrotron x-ray sources is shown. (L.C.) [pt

  4. Short Stature

    DEFF Research Database (Denmark)

    Christesen, Henrik Boye Thybo; Pedersen, Birgitte Tønnes; Pournara, Effie

    2016-01-01

    -scale, non-interventional, multinational study. The patient cohort consisted of 5996 short pediatric patients diagnosed with growth hormone deficiency (GHD), Turner syndrome (TS) or born small for gestational age (SGA). The proportions of children with baseline height standard deviation score (SDS) below......The use of appropriate growth standards/references is of significant clinical importance in assessing the height of children with short stature as it may determine eligibility for appropriate therapy. The aim of this study was to determine the impact of using World Health Organization (WHO) instead...... of national growth standards/references on height assessment in short children. Data were collected from routine clinical practice (1998-2014) from nine European countries that have available national growth references and were enrolled in NordiNet® International Outcome Study (IOS) (NCT00960128), a large...

  5. Strip defect recognition in electrical tests of silicon microstrip sensors

    Energy Technology Data Exchange (ETDEWEB)

    Valentan, Manfred, E-mail: valentan@mpp.mpg.de

    2017-02-11

    This contribution describes the measurement procedure and data analysis of AC-coupled double-sided silicon microstrip sensors with polysilicon resistor biasing. The most thorough test of a strip sensor is an electrical measurement of all strips of the sensor; the measured observables include e.g. the strip's current and the coupling capacitance. These measurements are performed to find defective strips, e.g. broken capacitors (pinholes) or implant shorts between two adjacent strips. When a strip has a defect, its observables will show a deviation from the “typical value”. To recognize and quantify certain defects, it is necessary to determine these typical values, i.e. the values the observables would have without the defect. As a novel approach, local least-median-of-squares linear fits are applied to determine these “would-be” values of the observables. A least-median-of-squares fit is robust against outliers, i.e. it ignores the observable values of defective strips. Knowing the typical values allows to recognize, distinguish and quantify a whole range of strip defects. This contribution explains how the various defects appear in the data and in which order the defects can be recognized. The method has been used to find strip defects on 30 double-sided trapezoidal microstrip sensors for the Belle II Silicon Vertex Detector, which have been measured at the Institute of High Energy Physics, Vienna (Austria).

  6. Investigation of the growth defects in strontium titanate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kulagin, N A; Landar, S V; Podus, L P [Khar' kovskij Gosudarstvennyj Univ. (Ukrainian SSR)

    1981-02-01

    Investigation results of characteristics and reasons for formation of macroscopic growth defects in SrTiO/sub 3/ monocrystals grown up by Wernail method are presented. It is shown that blue colour occurring in the specimen volume is caused by shortage of oxygen during growing which results in transition of some ions from tetravalent to trivalent state. The defect of another type is characterized by increased content of Fe and Ni oxides.

  7. Adrenomedullin increased the short-circuit current in the pig oviduct through chloride channels via the CGRP receptor: mediation by cAMP and calcium ions but not by nitric oxide.

    Science.gov (United States)

    Liao, S B; Cheung, K H; Cheung, M P L; To, Y T; O, W S; Tang, F

    2013-10-01

    The oviduct serves as a site for the fertilization of the ovum and the transport of the conceptus down to the uterus for implantation. In this study, we investigated the presence of adrenomedullin (ADM) and its receptor component proteins in the pig oviduct. The effect of ADM on oviductal secretion, the specific receptor, and the mechanisms involved were also investigated. The presence of ADM and its receptor component proteins in the pig oviduct were confirmed using immunostaining. Short-circuit current (I(sc)) technique was employed to study chloride ion secretion in the oviductal epithelium. ADM increased I(sc) through cAMP- and calcium-activated chloride channels, and this effect could be inhibited by the CGRP receptor antagonist, hCGRP8-37. In contrast, the nitric oxide synthase inhibitor, L-NG-nitroarginine methyl ester (L-NAME), could not block the effect of ADM on I(sc). In summary, ADM may increase oviductal fluid secretion via chloride secretion independent of the nitric oxide pathway for the transport of sperm and the conceptus.

  8. Upregulation of transcription factor NRF2-mediated oxidative stress response pathway in rat brain under short-term chronic hypobaric hypoxia.

    Science.gov (United States)

    Sethy, Niroj Kumar; Singh, Manjulata; Kumar, Rajesh; Ilavazhagan, Govindasamy; Bhargava, Kalpana

    2011-03-01

    Exposure to high altitude (and thus hypobaric hypoxia) induces electrophysiological, metabolic, and morphological modifications in the brain leading to several neurological clinical syndromes. Despite the known fact that hypoxia episodes in brain are a common factor for many neuropathologies, limited information is available on the underlying cellular and molecular mechanisms. In this study, we investigated the temporal effect of short-term (0-12 h) chronic hypobaric hypoxia on global gene expression of rat brain followed by detailed canonical pathway analysis and regulatory network identification. Our analysis revealed significant alteration of 33, 17, 53, 81, and 296 genes (p stress response pathway and genes were detected at all time points suggesting activation of NRF2-ARE antioxidant defense system. The results were further validated by assessing the expression levels of selected genes in temporal as well as brain regions with quantitative RT-PCR and western blot. In conclusion, our whole brain approach with temporal monitoring of gene expression patterns during hypobaric hypoxia has resulted in (1) deciphering sequence of pathways and signaling networks activated during onset of hypoxia, and (2) elucidation of NRF2-orchestrated antioxidant response as a major intrinsic defense mechanism. The results of this study will aid in better understanding and management of hypoxia-induced brain pathologies.

  9. Observation of defects evolution in electronic materials

    Science.gov (United States)

    Jang, Jung Hun

    annealing, ion-implantation, and thermal oxidation. Advanced characterization techniques have been used to obtain information about strain, relaxation, layer thickness, elemental composition, defects, surface/interface morphology changes and so on. Based on the understanding of defects behavior during the strain relaxation after post thermal processes, a new manufacturing process to obtain highly-relaxed and thin Si1-xGex layers, which could be used as virtual substrates for strained-Si applications, was found.

  10. Finite volume form factors in the presence of integrable defects

    International Nuclear Information System (INIS)

    Bajnok, Z.; Buccheri, F.; Hollo, L.; Konczer, J.; Takacs, G.

    2014-01-01

    We developed the theory of finite volume form factors in the presence of integrable defects. These finite volume form factors are expressed in terms of the infinite volume form factors and the finite volume density of states and incorporate all polynomial corrections in the inverse of the volume. We tested our results, in the defect Lee–Yang model, against numerical data obtained by truncated conformal space approach (TCSA), which we improved by renormalization group methods adopted to the defect case. To perform these checks we determined the infinite volume defect form factors in the Lee–Yang model exactly, including their vacuum expectation values. We used these data to calculate the two point functions, which we compared, at short distance, to defect CFT. We also derived explicit expressions for the exact finite volume one point functions, which we checked numerically. In all of these comparisons excellent agreement was found

  11. A criterion and mechanism for power ramp defects

    International Nuclear Information System (INIS)

    Garlick, A.; Gravenor, J.G.

    1978-02-01

    The problem of power ramp defects in water reactor fuel pins is discussed in relation to results recently obtained from ramp experiments in the Steam Generating Heavy Water Reactor. Cladding cracks in the defected fuel pins were similar, both macro- and micro structurally, to those in unirradiated Zircaloy exposed to iodine stress-corrosion cracking (scc) conditions. Furthermore, when the measured stress levels for scc in short-term tests were taken as a criterion for ramp defects, UK fuel modelling codes were found to give a useful indication of defect probability under reactor service conditions. The likelihood of sticking between fuel and cladding is discussed and evidence presented which suggests that even at power a degree of adhesion may be expected in some fuel pins. The ramp defect mechanism is discussed in terms of fission product scc, initiation being by intergranular penetration and propagation by cleavage when suitably orientated grains are exposed to large dilatational stresses ahead of the main crack. (author)

  12. Defect detection module

    International Nuclear Information System (INIS)

    Ernwein, R.; Westermann, G.

    1986-01-01

    The ''defect detector'' module is aimed at exceptional event or state recording. Foreseen for voltage presence monitoring on high supply voltage module of drift chambers, its characteristics can also show up the vanishing of supply voltage and take in account transitory fast signals [fr

  13. Quantum computing with defects.

    Science.gov (United States)

    Weber, J R; Koehl, W F; Varley, J B; Janotti, A; Buckley, B B; Van de Walle, C G; Awschalom, D D

    2010-05-11

    Identifying and designing physical systems for use as qubits, the basic units of quantum information, are critical steps in the development of a quantum computer. Among the possibilities in the solid state, a defect in diamond known as the nitrogen-vacancy (NV(-1)) center stands out for its robustness--its quantum state can be initialized, manipulated, and measured with high fidelity at room temperature. Here we describe how to systematically identify other deep center defects with similar quantum-mechanical properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate defect systems. To illustrate these points in detail, we compare electronic structure calculations of the NV(-1) center in diamond with those of several deep centers in 4H silicon carbide (SiC). We then discuss the proposed criteria for similar defects in other tetrahedrally coordinated semiconductors.

  14. Short Review

    DEFF Research Database (Denmark)

    Lynnerup, Niels; Rühli, Frank

    2015-01-01

    modality in ancient mummy research. The aim of this short review is to address the advantages and pitfalls of this particular technique for such unique samples. We recommend that when results of X-ray examination of mummies are presented, the specific recording data should be listed, and any given finds...

  15. Short fusion

    CERN Multimedia

    2002-01-01

    French and UK researchers are perfecting a particle accelerator technique that could aid the quest for fusion energy or make X-rays that are safer and produce higher-resolution images. Led by Dr Victor Malka from the Ecole Nationale Superieure des Techniques Avancees in Paris, the team has developed a better way of accelerating electrons over short distances (1 page).

  16. Short communication

    African Journals Online (AJOL)

    UPuser

    Short communication. Polymorphisms of the CAST gene in the Meishan and five other pig populations in China. Q.S. Wang. 1. , Y.C. Pan. 1#. , L.B. Sun. 2 and H. Meng. 1. 1 Department of Animal Science, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai. 201101, P.R. China. 2 Shanghai Institute of ...

  17. Short communication

    NARCIS (Netherlands)

    Pantophlet, Andre J.; Gilbert, M.S.; Gerrits, W.J.J.; Vonk, R.J.

    2017-01-01

    Heavy veal calves (4-6 mo old) often develop problems with insulin sensitivity. This could lead to metabolic disorders and impaired animal growth performance. Studies in various animal species have shown that the supplementation of short-chain fructo-oligosaccharides (scFOS) can improve insulin

  18. The quantum defect: Early history and recent developments

    International Nuclear Information System (INIS)

    Rau, A.R.; Inokuti, M.

    1997-01-01

    The notion of the quantum defect is important in atomic and molecular spectroscopy and also in unifying spectroscopy with collision theory. In the latter context, the quantum defect may be viewed as an ancestor of the phase shift. However, the origin of the term open-quotes quantum defectclose quotes does not seem to be explained in standard textbooks. It occurred in a 1921 paper by Schroedinger, preceding quantum mechanics, yet giving the correct meaning as an index of the short-range interactions with the core of an atom. We present the early history of the quantum-defect idea, and sketch its recent developments. copyright 1997 American Association of Physics Teachers

  19. Short Communication

    African Journals Online (AJOL)

    huis

    Short Communication. QTL analysis of production traits on SSC3 in a Large White×Meishan pig resource family. B. Zuo. 1. , Y.Z. Xiong. 1#. , Y.H. Su. 2. , C.Y. Deng. 1. , M.G. Lei. 1. , F.E. Li. 1. , R. Zheng. 1 and S.W. Jiang. 1. 1 Key Laboratory of Swine Genetics and Breeding, Ministry of Agriculture & Key Lab of Agricultural ...

  20. Congenital Heart Defects (For Parents)

    Science.gov (United States)

    ... to be associated with genetic disorders, such as Down syndrome . But the cause of most congenital heart defects isn't known. While they can't be prevented, many treatments are available for the defects and related health ...

  1. Antigravity from a spacetime defect

    OpenAIRE

    Klinkhamer, F. R.; Queiruga, J. M.

    2018-01-01

    We argue that there may exist spacetime defects embedded in Minkowski spacetime, which have negative active gravitational mass. One such spacetime defect then repels a test particle, corresponding to what may be called "antigravity."

  2. Modulation of mitochondrial morphology by bioenergetics defects in primary human fibroblasts

    DEFF Research Database (Denmark)

    Guillery, O.; Malka, F.; Frachon, P.

    2008-01-01

    induced partial but significant mitochondrial fragmentation, whereas dissipation of mitochondrial membrane potential (D Psi m) provoked complete fragmentation, and glycolysis inhibition had no effect. Oxidative phosphorylation defective fibroblasts had essentially normal filamentous mitochondria under...... basal conditions, although when challenged some of them presented with mild alteration of fission or fusion efficacy. Severely defective cells disclosed complete mitochondrial fragmentation under glycolysis inhibition. In conclusion, mitochondrial morphology is modulated by D Psi m but loosely linked...... to mitochondrial oxidative phosphorylation. Its alteration by glycolysis, inhibition points to a severe oxidative phosphorylation defect. (C) 2008 Elsevier B.V. All rights reserved Udgivelsesdato: 2008/4...

  3. Studies of defects and defect agglomerates by positron annihilation spectroscopy

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard; Singh, B.N.

    1997-01-01

    A brief introduction to positron annihilation spectroscopy (PAS), and in particular lo its use for defect studies in metals is given. Positrons injected into a metal may become trapped in defects such as vacancies, vacancy clusters, voids, bubbles and dislocations and subsequently annihilate from...... the trapped state iri the defect. The annihilation characteristics (e.g., the lifetime of the positron) can be measured and provide information about the nature of the defect (e.g., size, density, morphology). The technique is sensitive to both defect size (in the range from monovacancies up to cavities...

  4. Congenital Heart Defects and CCHD

    Science.gov (United States)

    ... and more. Stony Point, NY 10980 Close X Home > Complications & Loss > Birth defects & other health conditions > Congenital heart defects and ... in congenital heart defects. You have a family history of congenital heart ... syndrome or VCF. After birth Your baby may be tested for CCHD as ...

  5. Structural organization of the human short-chain acyl-CoA dehydrogenase gene

    DEFF Research Database (Denmark)

    Corydon, M J; Andresen, B S; Bross, P

    1997-01-01

    Short-chain acyl-CoA dehydrogenase (SCAD) is a homotetrameric mitochondrial flavoenzyme that catalyzes the initial reaction in short-chain fatty acid beta-oxidation. Defects in the SCAD enzyme are associated with failure to thrive, often with neuromuscular dysfunction and elevated urinary excretion...... shown to be associated with ethylmalonic aciduria. From analysis of 18 unrelated Danish families, we show that the four SCAD gene polymorphisms constitute five allelic variants of the SCAD gene, and that the 625A variant together with the less frequent variant form of the three other polymorphisms (321C....... The evolutionary relationship between SCAD and five other members of the acyl-CoA dehydrogenase family was investigated by two independent approaches that gave similar phylogenetic trees....

  6. Systematic study of the short-term instability of PbWO4 scintillator parameters under irradiation

    International Nuclear Information System (INIS)

    Annenkov, A.N.; Ligun, A.B.; Auffray, E.; Lecoq, P.; Chipaux, R.; Geleoc, M.; Drobychev, G. Yu; Fedorov, A.A.; Korzhik, M.V.; Missevitch, O.V.; Pavlenko, V.B.; Golubev, N.A.; Lednev, A.A.; Peigneux, J.-P.; Singovski, A.V.

    1998-01-01

    The effect of irradiation on lead tungstate PbWO 4 (PWO) scintillator properties has been studied at different irradiation facilities. Lead tungstate crystals, grown with the oxide content in the melt tuned to the stoichiometry of pure sheelite or sheelite-like crystal types and doped with heterovalent, trivalent and pentavalent impurities, have been studied in order to optimize their resistance to irradiation. A combination of a selective cleaning of raw materials, a tuning of the melt from crystallization to crystallization and a destruction or compensation of the point-structure defects has to be used to minimize the short-term instability of PWO parameters under irradiation

  7. Immobile defects in ferroelastic walls: Wall nucleation at defect sites

    Science.gov (United States)

    He, X.; Salje, E. K. H.; Ding, X.; Sun, J.

    2018-02-01

    Randomly distributed, static defects are enriched in ferroelastic domain walls. The relative concentration of defects in walls, Nd, follows a power law distribution as a function of the total defect concentration C: N d ˜ C α with α = 0.4 . The enrichment Nd/C ranges from ˜50 times when C = 10 ppm to ˜3 times when C = 1000 ppm. The resulting enrichment is due to nucleation at defect sites as observed in large scale MD simulations. The dynamics of domain nucleation and switching is dependent on the defect concentration. Their energy distribution follows the power law with exponents during yield between ɛ ˜ 1.82 and 2.0 when the defect concentration increases. The power law exponent is ɛ ≈ 2.7 in the plastic regime, independent of the defect concentration.

  8. Benign gastric filling defect

    International Nuclear Information System (INIS)

    Oh, K. K.; Lee, Y. H.; Cho, O. K.; Park, C. Y.

    1979-01-01

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  9. Benign gastric filling defect

    Energy Technology Data Exchange (ETDEWEB)

    Oh, K. K.; Lee, Y. H.; Cho, O. K.; Park, C. Y. [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    1979-06-15

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  10. Benign gastric filling defect

    Energy Technology Data Exchange (ETDEWEB)

    Oh, K K; Lee, Y H; Cho, O K; Park, C Y [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    1979-06-15

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  11. A new type of lethal short-limbed dwarfism

    International Nuclear Information System (INIS)

    Nairn, E.R.; Chapman, S.

    1989-01-01

    Details are presented of a most unusual osteo-chondrodysplasia which presents with lethal neonatal short-limbed dwarfism, defective ossification and nodular calcification with cartilage. The features resemble one case previously described in the literature. (orig.)

  12. New type of lethal short-limbed dwarfism

    Energy Technology Data Exchange (ETDEWEB)

    Nairn, E.R.; Chapman, S.

    1989-05-01

    Details are presented of a most unusual osteo-chondrodysplasia which presents with lethal neonatal short-limbed dwarfism, defective ossification and nodular calcification with cartilage. The features resemble one case previously described in the literature.

  13. Short curcumin treatment modulates oxidative stress, arginase activity, aberrant crypt foci, and TGF-β1 and HES-1 transcripts in 1,2-dimethylhydrazine-colon carcinogenesis in mice

    International Nuclear Information System (INIS)

    Bounaama, Abdelkader; Djerdjouri, Bahia; Laroche-Clary, Audrey; Le Morvan, Valérie; Robert, Jacques

    2012-01-01

    Highlights: ► 1,2-Dimethylhydrazine (DMH) toxicity was driven by oxidative stress. ► Arginase activity correlated to aberrant crypt foci (ACF). ► Curcumin diet restored redox status and induced apoptosis of dysplastic ACF. ► Curcumin reduced arginase activity and up regulated TGF-β1 and HES-1 transcripts. -- Abstract: This study investigated the effect of short curcumin treatment, a natural antioxidant on 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) in mice. The incidence of aberrant crypt foci (ACF) was 100%, with 54 ± 6 per colon, 10 weeks after the first DMH injection and reached 67 ± 12 per colon after 12 weeks. A high level of undifferentiated goblet cells and a weak apoptotic activity were shown in dysplastic ACF. The morphological alterations of colonic mucosa were associated to severe oxidative stress ratio with 43% increase in malondialdehyde vs. 36% decrease in GSH. DMH also increased inducible nitric synthase (iNOS) mRNA transcripts (250%), nitrites level (240%) and arginase activity (296%), leading to nitrosative stress and cell proliferation. Curcumin treatment, starting at week 10 post-DMH injection for 14 days, reduced the number of ACF (40%), iNOS expression (25%) and arginase activity (73%), and improved redox status by approximately 46%, compared to DMH-treated mice. Moreover, curcumin induced apoptosis of dysplastic ACF cells without restoring goblet cells differentiation. Interestingly, curcumin induced a parallel increase in TGF-β1 and HES-1 transcripts (42% and 26%, respectively). In conclusion, the protective effect of curcumin was driven by the reduction of arginase activity and nitrosative stress. The up regulation of TGF-β1 and HES-1 expression by curcumin suggests for the first time, a potential interplay between these signalling pathways in the chemoprotective mechanism of curcumin.

  14. Expeditious low-temperature sintering of copper nanoparticles with thin defective carbon shells

    Science.gov (United States)

    Kim, Changkyu; Lee, Gyoungja; Rhee, Changkyu; Lee, Minku

    2015-04-01

    The realization of air-stable nanoparticles, well-formulated nanoinks, and conductive patterns based on copper is a great challenge in low-cost and large-area flexible printed electronics. This work reports the synthesis of a conductively interconnected copper structure via thermal sintering of copper inks at a low temperature for a short period of time, with the help of thin defective carbon shells coated onto the copper nanoparticles. Air-stable copper/carbon core/shell nanoparticles (typical size ~23 nm, shell thickness ~1.0 nm) are prepared by means of an electric explosion of wires. Gaseous oxidation of the carbon shells with a defective structure occurs at 180 °C, impacting the choice of organic solvents as well as the sintering conditions to create a crucial neck formation. Isothermal oxidation and reduction treatment at 200 °C for only about 10 min yields an oxide-free copper network structure with an electrical resistivity of 25.1 μΩ cm (14.0 μΩ cm at 250 °C). Finally, conductive copper line patterns are achieved down to a 50 μm width with an excellent printing resolution (standard deviation ~4.0%) onto a polyimide substrate using screen printing of the optimized inks.The realization of air-stable nanoparticles, well-formulated nanoinks, and conductive patterns based on copper is a great challenge in low-cost and large-area flexible printed electronics. This work reports the synthesis of a conductively interconnected copper structure via thermal sintering of copper inks at a low temperature for a short period of time, with the help of thin defective carbon shells coated onto the copper nanoparticles. Air-stable copper/carbon core/shell nanoparticles (typical size ~23 nm, shell thickness ~1.0 nm) are prepared by means of an electric explosion of wires. Gaseous oxidation of the carbon shells with a defective structure occurs at 180 °C, impacting the choice of organic solvents as well as the sintering conditions to create a crucial neck formation

  15. Passivation of defect states in Si and Si/SiO2 interface states by cyanide treatment: improvement of characteristics of pin-junction amorphous Si and crystalline Si-based metal-oxide-semiconductor junction solar cells

    International Nuclear Information System (INIS)

    Fujiwara, N.; Fujinaga, T.; Niinobe, D.; Maida, O.; Takahashi, M.; Kobayashi, H.

    2003-01-01

    Defect states in Si can be passivated by cyanide treatment which simply involves immersion of Si materials in KCN solutions, followed by rinse. When the cyanide treatment is applied to pin-junction amorphous Si [a-Si] solar cells, the initial conversion efficiency increases. When the crown-ether cyanide treatment using a KCN solution of xylene containing 18-crown-6 is performed on i-a-Si films, decreases in the photo- and dark current densities with the irradiation time are prevented. The cyanide treatment can also passivate interface states present at Si/SiO 2 interfaces, leading to an increase in the conversion efficiency of 2 / Si (100)> solar cells.. Si-CN bonds formed by the reaction of defect states with cyanide ions have a high bond energy of about 4.5 eV and hence heat treatment at 800 0 C does not rupture the bonds, making thermal stability of the cyanide treatment.. When the cyanide treatment is applied to ultrathin SiO 2 /Si structure, the leakage current density is markedly decreased (Authors)

  16. Surface defects and chiral algebras

    Energy Technology Data Exchange (ETDEWEB)

    Córdova, Clay [School of Natural Sciences, Institute for Advanced Study,1 Einstein Dr, Princeton, NJ 08540 (United States); Gaiotto, Davide [Perimeter Institute for Theoretical Physics,31 Caroline St N, Waterloo, ON N2L 2Y5 (Canada); Shao, Shu-Heng [School of Natural Sciences, Institute for Advanced Study,1 Einstein Dr, Princeton, NJ 08540 (United States)

    2017-05-26

    We investigate superconformal surface defects in four-dimensional N=2 superconformal theories. Each such defect gives rise to a module of the associated chiral algebra and the surface defect Schur index is the character of this module. Various natural chiral algebra operations such as Drinfeld-Sokolov reduction and spectral flow can be interpreted as constructions involving four-dimensional surface defects. We compute the index of these defects in the free hypermultiplet theory and Argyres-Douglas theories, using both infrared techniques involving BPS states, as well as renormalization group flows onto Higgs branches. In each case we find perfect agreement with the predicted characters.

  17. Point defects in nickel

    International Nuclear Information System (INIS)

    Peretto, P.

    1969-01-01

    The defects in electron irradiated nickel (20 deg. K) or neutron irradiated nickel (28 deg. K) are studied by simultaneous analysis using the magnetic after-effect, electron microscopy and electrical resistivity recovery. We use zone refined nickel (99.999 per cent) which, for some experiments, is alloyed with a small amount of iron (for example 0.1 per cent Fe). The temperature dependant electrical recovery may be divided in four stages. The sub-stages I B (31 deg. K), I C (42 deg. K), I D (from to 57 deg. K) and I E (62 deg. K) of stage I are due to the disappearance of single interstitials into vacancies. The interstitial defect has a split configuration with a migration energy of about 0.15 eV. In the close pair which disappears in stage I B the interstitial is found to be in a 3. neighbour position whilst in stage I D it is near the direction from the vacancy. In stage I E there is no longer any interaction between the interstitial and the vacancy. The stage II is due to more complicated interstitial defects: di-interstitials for stage II B (84 deg. K) and larger and larger interstitial loops for the following sub-stages. The loops may be seen by electron microscopy. Impurities can play the role of nucleation centers for the loops. Stages III A (370 deg. K) and III B (376 deg. K) are due to two types of di-vacancies. During stage IV (410 deg. K) the single vacancies migrate. Vacancy type loops and interstitial type loops grow concurrently and disappear at about 800 deg. K as observed by electron microscopy. (author) [fr

  18. Towards point of care testing for C. difficile infection by volatile profiling, using the combination of a short multi-capillary gas chromatography column with metal oxide sensor detection

    International Nuclear Information System (INIS)

    McGuire, N D; Ewen, R J; De Lacy Costello, B; Garner, C E; Vaughan, K; Ratcliffe, N M; Probert, C S J

    2014-01-01

    Rapid volatile profiling of stool sample headspace was achieved using a combination of short multi-capillary chromatography column (SMCC), highly sensitive heated metal oxide semiconductor sensor and artificial neural network software. For direct analysis of biological samples this prototype offers alternatives to conventional gas chromatography (GC) detectors and electronic nose technology. The performance was compared to an identical instrument incorporating a long single capillary column (LSCC). The ability of the prototypes to separate complex mixtures was assessed using gas standards and homogenized in house ‘standard’ stool samples, with both capable of detecting more than 24 peaks per sample. The elution time was considerably faster with the SMCC resulting in a run time of 10 min compared to 30 min for the LSCC. The diagnostic potential of the prototypes was assessed using 50 C. difficile positive and 50 negative samples. The prototypes demonstrated similar capability of discriminating between positive and negative samples with sensitivity and specificity of 85% and 80% respectively. C. difficile is an important cause of hospital acquired diarrhoea, with significant morbidity and mortality around the world. A device capable of rapidly diagnosing the disease at the point of care would reduce cases, deaths and financial burden. (paper)

  19. Defect detection using transient thermography

    International Nuclear Information System (INIS)

    Mohd Zaki Umar; Ibrahim Ahmad; Ab Razak Hamzah; Wan Saffiey Wan Abdullah

    2008-08-01

    An experimental research had been carried out to study the potential of transient thermography in detecting sub-surface defect of non-metal material. In this research, eight pieces of bakelite material were used as samples. Each samples had a sub-surface defect in the circular shape with different diameters and depths. Experiment was conducted using one-sided Pulsed Thermal technique. Heating of samples were done using 30 kWatt adjustable quartz lamp while infra red (IR) images of samples were recorded using THV 550 IR camera. These IR images were then analysed with ThermofitTMPro software to obtain the Maximum Absolute Differential Temperature Signal value, ΔΤ m ax and the time of its appearance, τ m ax (ΔΤ). Result showed that all defects were able to be detected even for the smallest and deepest defect (diameter = 5 mm and depth = 4 mm). However the highest value of Differential Temperature Signal (ΔΤ m ax), were obtained at defect with the largest diameter, 20 mm and at the shallowest depth, 1 mm. As a conclusion, the sensitivity of the pulsed thermography technique to detect sub-surface defects of bakelite material is proportionately related with the size of defect diameter if the defects are at the same depth. On the contrary, the sensitivity of the pulsed thermography technique inversely related with the depth of defect if the defects have similar diameter size. (Author)

  20. Dipole defects in beryl

    International Nuclear Information System (INIS)

    Holanda, B A; Cordeiro, R C; Blak, A R

    2010-01-01

    Dipole defects in gamma irradiated and thermally treated beryl (Be 3 Al 2 Si 6 O 18 ) samples have been studied using the Thermally Stimulated Depolarization Currents (TSDC) technique. TSDC experiments were performed in pink (morganite), green (emerald), blue (aquamarine) and colourless (goshenite) natural beryl. TSDC spectra present dipole peaks at 190K, 220K, 280K and 310K that change after gamma irradiation and thermal treatments. In morganite samples, for thermal treatments between 700K and 1100K, the 280K peak increase in intensity and the band at 220K disappears. An increase of the 280K peak and a decrease of the 190K peak were observed in the TSDC spectra of morganite after a gamma irradiation of 25kGy performed after the thermal treatments. In the case of emerald samples, thermal treatments enhanced the 280K peak and gamma irradiation partially destroyed this band. The goshenite TSDC spectra present only one band at 280K that is not affected either by thermal treatments or by gamma irradiation. All the observed peaks are of dipolar origin because the intensity of the bands is linearly dependent on the polarization field, behaviour of dipole defects. The systematic study, by means of TSDC measurements, of ionizing irradiation effects and thermal treatments in these crystals makes possible a better understanding of the role played by the impurities in beryl crystals.

  1. Modeling charged defects inside density functional theory band gaps

    International Nuclear Information System (INIS)

    Schultz, Peter A.; Edwards, Arthur H.

    2014-01-01

    Density functional theory (DFT) has emerged as an important tool to probe microscopic behavior in materials. The fundamental band gap defines the energy scale for charge transition energy levels of point defects in ionic and covalent materials. The eigenvalue gap between occupied and unoccupied states in conventional DFT, the Kohn–Sham gap, is often half or less of the experimental band gap, seemingly precluding quantitative studies of charged defects. Applying explicit and rigorous control of charge boundary conditions in supercells, we find that calculations of defect energy levels derived from total energy differences give accurate predictions of charge transition energy levels in Si and GaAs, unhampered by a band gap problem. The GaAs system provides a good theoretical laboratory for investigating band gap effects in defect level calculations: depending on the functional and pseudopotential, the Kohn–Sham gap can be as large as 1.1 eV or as small as 0.1 eV. We find that the effective defect band gap, the computed range in defect levels, is mostly insensitive to the Kohn–Sham gap, demonstrating it is often possible to use conventional DFT for quantitative studies of defect chemistry governing interesting materials behavior in semiconductors and oxides despite a band gap problem

  2. Characterisation and modelling of defect formation in direct-chill cast AZ80 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mackie, D.; Robson, J.D.; Withers, P.J. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Turski, M. [Magnesium Elektron UK, Rake Lane, Manchester, M27 8BF (United Kingdom)

    2015-06-15

    Wrought magnesium alloys for demanding structural applications require high quality defect free cast feedstock. The aim of this study was to first identify and characterise typical defects in direct chill cast magnesium–aluminium–zinc (AZ) alloy billet and then use modelling to understand the origins of these defects so they can be prevented. Defects were first located using ultrasonic inspection and were then characterised using X-ray computed tomography (XCT) and serial sectioning, establishing the presence of oxide films and intermetallic particles Al{sub 8}Mn{sub 5} in all defects. A model was developed to predict the flow patterns and growth kinetics of the intermetallic phases during casting, which influence the formation of defects. Simulation of the growth of the intermetallic particles demonstrated that precipitation from the liquid occurs in the mould. The combination of the entrained oxide films and intermetallic particles recirculates in the liquid metal and continues to grow, until large enough to settle, which is predicted to occur at the centre of the mould where the flow is the slowest. Based on these predictions, strategies to reduce the susceptibility to defect formation are suggested. - Highlights: • Casting defects in magnesium direct chill casting have been imaged and characterised in 3-dimensions. • The occurrences of co-located clusters of particles and oxide films have been characterised and explained. • A coupled model has been developed to help interpret the observed trend for defects located towards the centre of billets.

  3. Characterisation and modelling of defect formation in direct-chill cast AZ80 alloy

    International Nuclear Information System (INIS)

    Mackie, D.; Robson, J.D.; Withers, P.J.; Turski, M.

    2015-01-01

    Wrought magnesium alloys for demanding structural applications require high quality defect free cast feedstock. The aim of this study was to first identify and characterise typical defects in direct chill cast magnesium–aluminium–zinc (AZ) alloy billet and then use modelling to understand the origins of these defects so they can be prevented. Defects were first located using ultrasonic inspection and were then characterised using X-ray computed tomography (XCT) and serial sectioning, establishing the presence of oxide films and intermetallic particles Al 8 Mn 5 in all defects. A model was developed to predict the flow patterns and growth kinetics of the intermetallic phases during casting, which influence the formation of defects. Simulation of the growth of the intermetallic particles demonstrated that precipitation from the liquid occurs in the mould. The combination of the entrained oxide films and intermetallic particles recirculates in the liquid metal and continues to grow, until large enough to settle, which is predicted to occur at the centre of the mould where the flow is the slowest. Based on these predictions, strategies to reduce the susceptibility to defect formation are suggested. - Highlights: • Casting defects in magnesium direct chill casting have been imaged and characterised in 3-dimensions. • The occurrences of co-located clusters of particles and oxide films have been characterised and explained. • A coupled model has been developed to help interpret the observed trend for defects located towards the centre of billets

  4. Investigation of the crystal lattice defects by means of the positrons annihilations

    International Nuclear Information System (INIS)

    Dryzek, J.

    1994-01-01

    In this report the positrons annihilation methods as a tool for the crystal defects studies is presented. The short description of the positron - crystal interactions and different positron capture models are discussed. 192 refs, 67 figs, 6 tabs

  5. Computer simulation of defect cluster

    Energy Technology Data Exchange (ETDEWEB)

    Kuramoto, Eiichi [Kyushu Univ., Kasuga, Fukuoka (Japan). Research Inst. for Applied Mechanics

    1996-04-01

    In order to elucidate individual element process of various defects and defect clusters of used materials under irradiation environments, interatomic potential with reliability was investigated. And for comparison with experimental results, it is often required to adopt the temperature effect and to investigate in details mechanism of one dimensional motion of micro conversion loop and so forth using the molecular dynamic (MD) method. Furthermore, temperature effect is also supposed for stable structure of defects and defect clusters, and many problems relating to alloy element are also remained. And, simulation on photon life at the defects and defect clusters thought to be important under comparison with equipment can also be supposed an improvement of effectiveness due to relation to theses products. In this paper, some topics in such flow was extracted to explain them. In particular, future important problems will be potential preparation of alloy, structure, dynamic behavior and limited temperature of intralattice atomic cluster. (G.K.)

  6. Study on defects and impurities in cast-grown polycrystalline silicon substrates for solar cells

    International Nuclear Information System (INIS)

    Arafune, K.; Sasaki, T.; Wakabayashi, F.; Terada, Y.; Ohshita, Y.; Yamaguchi, M.

    2006-01-01

    We focused on the defects and impurities in polycrystalline silicon substrates, which deteriorate solar cell efficiency. Comparison of the minority carrier lifetime with the grain size showed that the region with short minority carrier lifetimes did not correspond to the region with small grains. Conversely, the minority carrier lifetime decreased as the etch-pit density (EPD) increased, suggesting that the minority carrier lifetime is strongly affected by the EPD. Electron beam induced current measurements revealed that a combination of grain boundaries and point defects had high recombination activity. Regarding impurities, the interstitial oxygen concentration was relatively low compared with that in a Czochralski-grown silicon substrate, the total carbon concentration exceeded the solubility limit of silicon melt. X-ray microprobe fluorescence measurements revealed a large amount of iron in the regions where there were many etch-pits and grain boundaries with etch-pits. X-ray absorption near edge spectrum analysis revealed trapped iron in the form of oxidized iron

  7. Topological defects in extended inflation

    International Nuclear Information System (INIS)

    Copeland, E.J.; Kolb, E.W.; Chicago Univ., IL; Liddle, A.R.

    1990-04-01

    We consider the production of topological defects, especially cosmic strings, in extended inflation models. In extended inflation, the Universe passes through a first-order phase transition via bubble percolation, which naturally allows defects to form at the end of inflation. The correlation length, which determines the number density of the defects, is related to the mean size of bubbles when they collide. This mechanism allows a natural combination of inflation and large-scale structure via cosmic strings. 18 refs

  8. Defects in new protective aprons

    International Nuclear Information System (INIS)

    Glaze, S.; LeBlanc, A.D.; Bushong, S.C.

    1984-01-01

    Upon careful examination, several defects have been detected in new protective aprons. The nature of the defects is identified and described. Although the occurrence of such defects has not exceeded 5%, they are significant enough to warrant return of the lead apron to the supplier. It is recommended that the integrity of all new protective aprons be verified upon receipt as well as at yearly intervals

  9. Topological defects in extended inflation

    International Nuclear Information System (INIS)

    Copeland, E.J.; Kolb, E.W.; Liddle, A.R.

    1990-01-01

    We consider the production of topological defects, especially cosmic strings, in extended-inflation models. In extended inflation, the Universe passes through a first-order phase transition via bubble percolation, which naturally allows defects to form at the end of inflation. The correlation length, which determines the number density of the defects, is related to the mean size of the bubbles when they collide. This mechanism allows a natural combination of inflation and large-scale structure via cosmic strings

  10. Metastable gravity on classical defects

    International Nuclear Information System (INIS)

    Ringeval, Christophe; Rombouts, Jan-Willem

    2005-01-01

    We discuss the realization of metastable gravity on classical defects in infinite-volume extra dimensions. In dilatonic Einstein gravity, it is found that the existence of metastable gravity on the defect core requires violation of the dominant energy condition for codimension N c =2 defects. This is illustrated with a detailed analysis of a six-dimensional hyperstring minimally coupled to dilaton gravity. We present the general conditions under which a codimension N c >2 defect admits metastable modes, and find that they differ from lower codimensional models in that, under certain conditions, they do not require violation of energy conditions to support quasilocalized gravity

  11. Fibrous metaphyseal defects

    International Nuclear Information System (INIS)

    Hajek, P.C.; Ritschi, P.; Kramer, J.; Imhof, H.; Karnel, F.

    1988-01-01

    Eighty-two patients (107 fibrous metaphyseal defects [FMDs]) were investigated with standard radiography and MR imaging (N = 15). Twenty-two of these were followed up sequentially up to 10 years (mean, 7.3 years). Histologic studies proved that FMDs originate at the site of insertion of a tendon in the perichondrium of the epiphyseal cartilage. After normal bone growth is regained, all FMDs were found to move diaphysically, following a straight line parallel to the long axis of the FMDs. This line pointed to the insertion of the tendon originally involved, a fact that was proved with MR imaging. Four characteristic stages were found to define a typical radiomorphologic course of an FMD

  12. Influence of surface defects on the tensile strength of carbon fibers

    Science.gov (United States)

    Vautard, F.; Dentzer, J.; Nardin, M.; Schultz, J.; Defoort, B.

    2014-12-01

    The mechanical properties of carbon fibers, especially their tensile properties, are affected by internal and surface defects. In order to asses in what extent the generation of surface defects can result in a loss of the mechanical properties, non-surface treated carbon fibers were oxidized with three different surface treatment processes: electro-chemical oxidation, oxidation in nitric acid, and oxidation in oxygen plasma. Different surface topographies and surface chemistries were obtained, as well as different types and densities of surface defects. The density of surface defects was measured with both a physical approach (Raman spectroscopy) and a chemical approach (Active Surface Area). The tensile properties were evaluated by determining the Weibull modulus and the scale parameter of each reference, after measuring the tensile strength for four different gauge lengths. A relationship between the tensile properties and the nature and density of surface defects was noticed, as large defects largely control the value of the tensile strength. When optimized, some oxidation surface treatment processes can generate surface functional groups as well as an increase of the mechanical properties of the fibers, because of the removal of the contamination layer of pyrolytic carbon generated during the carbonization of the polyacrylonitrile precursor. Oxidation in oxygen plasma revealed to be a promising technology for alternative surface treatment processes, as high levels of functionalization were achieved and a slight improvement of the mechanical properties was obtained too.

  13. A study of the electrical properties of defects in silicon

    International Nuclear Information System (INIS)

    Blood, A.M.

    1998-01-01

    This work contains the most comprehensive qualitative and quantitative electron beam induced current (EBIC) study of recombination at contaminated defects in silicon. It is also a rigorous quantitative investigation of the effect of hydrogen on individual transition metal contaminated defects. In addition, the recombination behaviour exhibited by point and extended defects has been investigated using EBIC and deep level transient spectroscopy (DLTS). As a result of these measurements, techniques for the preparation of transition metal contaminated specimens have been refined. Successful hydrogen passivation of copper, nickel and iron contaminated silicon specimens containing oxidation-induced stacking faults has been achieved in two experimental systems. It is found that hydrogen passivates those states that are deepest in the semiconductor band gap in preference to those that are shallow. Furthermore, it has been concluded that during hydrogen passivation treatment, even at low temperatures, unwanted metallic impurities can be introduced. Three types of recombination behaviour have been identified from the defects-studied in this work and they are discussed with relevance to present recombination models. An investigation of the recombination behaviour of defects that lie in the depletion region and in the specimen bulk has concluded that the recombination type observed is independent of the depth of the defect. Evidence for the presence of compound defects showing mixed recombination behaviour type is presented. In conclusion, it is postulated that the transition metal impurities introduce a 'band of states' with a range of energies rather than a single energy state. This proposal is provided as an explanation for the recombination types found in this work and the effect of the hydrogen passivation. This work is placed in context of previous investigations into the behaviour of dislocations in silicon in the presence of transition metals, and the ability of

  14. Phosphorus doped and defects engineered graphene for improved electrochemical sensing: synergistic effect of dopants and defects

    International Nuclear Information System (INIS)

    Chu, Ke; Wang, Fan; Tian, Ye; Wei, Zhen

    2017-01-01

    Heteroatom-doped graphene materials emerged as promising metal-free catalysts have recently attracted a growing interest in electrochemical sensing applications. However, their catalytic activity and sensing performances still need to be further improved. Herein, we reported the development of unique phosphorus (P)-doped and plasma-etched graphene (denoted as PG-E) as an efficient metal-free electrocatalyst for dopamine (DA) sensing. It was demonstrated that introducing both P-dopants and plasma-engineered defects in graphene could synergistically improve the activity toward electrocatalytic oxidation of DA by increasing the accessible active sites and promoting the electron transport capability. The resulting PG-E modified electrode showed exceptional DA sensing performances with low detection limit, high selectivity and good stability. These results suggested that the synergistic effect of dopants and defects might be an important factor for developing the advanced graphene-based metal-free catalysts for electrochemical sensing.

  15. Lumber defect detection by ultrasonics

    Science.gov (United States)

    K. A. McDonald

    1978-01-01

    Ultrasonics, the technology of high-frequency sound, has been developed as a viable means for locating most defects In lumber for use in digital form in decision-making computers. Ultrasonics has the potential for locating surface and internal defects in lumber of all species, green or dry, and rough sawn or surfaced.

  16. Neutron diffraction and lattice defects

    International Nuclear Information System (INIS)

    Hamaguchi, Yoshikazu

    1974-01-01

    Study on lattice defects by neutron diffraction technique is described. Wave length of neutron wave is longer than that of X-ray, and absorption cross-section is small. Number of defects observed by ESR is up to several defects, and the number studied with electron microscopes is more than 100. Information obtained by neutron diffraction concerns the number of defects between these two ranges. For practical analysis, several probable models are selected from the data of ESR or electron microscopes, and most probable one is determined by calculation. Then, defect concentration is obtained from scattering cross section. It is possible to measure elastic scattering exclusively by neutron diffraction. Minimum detectable concentration estimated is about 0.5% and 10 20 - 10 21 defects per unit volume. A chopper and a time of flight system are used as a measuring system. Cold neutrons are obtained from the neutron sources inserted into reactors. Examples of measurements by using similar equipments to PTNS-I system of Japan Atomic Energy Research Institute are presented. Interstitial concentration in the graphite irradiated by fast neutrons is shown. Defects in irradiated MgO were also investigated by measuring scattering cross section. Study of defects in Ge was made by measuring total cross section, and model analysis was performed in comparison with various models. (Kato, T.)

  17. Lectures on cosmic topological defects

    Energy Technology Data Exchange (ETDEWEB)

    Vachaspati, T [Department of Astronomy and Astrophysics, Colaba, Mumbai (India) and Physics Department, Case Western Reserve University, Cleveland (United States)

    2001-11-15

    These lectures review certain topological defects and aspects of their cosmology. Unconventional material includes brief descriptions of electroweak defects, the structure of domain walls in non-Abelian theories, and the spectrum of magnetic monopoles in SU(5) Grand Unified theory. (author)

  18. 2012 Gordon Research Conference on Defects in Semiconductors - Formal Schedule and Speaker/Poster Program

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, Evan [Naval Research Lab. (NRL), Washington, DC (United States)

    2012-08-17

    The meeting shall strive to develop and further the fundamental understanding of defects and their roles in the structural, electronic, optical, and magnetic properties of bulk, thin film, and nanoscale semiconductors and device structures. Point and extended defects will be addressed in a broad range of electronic materials of particular current interest, including wide bandgap semiconductors, metal-oxides, carbon-based semiconductors (e.g., diamond, graphene, etc.), organic semiconductors, photovoltaic/solar cell materials, and others of similar interest. This interest includes novel defect detection/imaging techniques and advanced defect computational methods.

  19. Electric field dependent paramagnetic defect creation in single step implanted Simox films

    International Nuclear Information System (INIS)

    Leray, J.L.; Margail, J.

    1991-01-01

    X irradiation induced oxygen-vacancy defect creation has been studied in SIMOX produced by single step implantation and annealing. It is shown that SIMOX is substantially more radiation sensitive (for these defects) than thermal or bulk oxide. Irradiation in the presence of an electric field 0.5 -1 MV cm -1 is found to enhance the rate of defect creation by ≥ 2 times. Further enhanced defect creation is observed in SIMOX samples whose substrate has been chemically thinned prior to irradiation. This enhancement is attributed to modification of the network induced by hydrogen introduced during the thinning process

  20. Toward Intelligent Software Defect Detection

    Science.gov (United States)

    Benson, Markland J.

    2011-01-01

    Source code level software defect detection has gone from state of the art to a software engineering best practice. Automated code analysis tools streamline many of the aspects of formal code inspections but have the drawback of being difficult to construct and either prone to false positives or severely limited in the set of defects that can be detected. Machine learning technology provides the promise of learning software defects by example, easing construction of detectors and broadening the range of defects that can be found. Pinpointing software defects with the same level of granularity as prominent source code analysis tools distinguishes this research from past efforts, which focused on analyzing software engineering metrics data with granularity limited to that of a particular function rather than a line of code.

  1. Holographic Chern-Simons defects

    International Nuclear Information System (INIS)

    Fujita, Mitsutoshi; Melby-Thompson, Charles M.; Meyer, René; Sugimoto, Shigeki

    2016-01-01

    We study SU(N) Yang-Mills-Chern-Simons theory in the presence of defects that shift the Chern-Simons level from a holographic point of view by embedding the system in string theory. The model is a D3-D7 system in Type IIB string theory, whose gravity dual is given by the AdS soliton background with probe D7 branes attaching to the AdS boundary along the defects. We holographically renormalize the free energy of the defect system with sources, from which we obtain the correlation functions for certain operators naturally associated to these defects. We find interesting phase transitions when the separation of the defects as well as the temperature are varied. We also discuss some implications for the Fractional Quantum Hall Effect and for 2-dimensional QCD.

  2. Defect forces, defect couples and path integrals in fracture mechanics

    International Nuclear Information System (INIS)

    Roche, R.L.

    1979-07-01

    In this work, it is shown that the path integrals can be introduced without any reference to the material behavior. The method is based on the definition in a continuous medium of a set of vectors and couples having the dimension of a force or a moment. More precisely, definitions are given of volume defect forces, surface defect forces, volume defect couples, and surface defect couples. This is done with the help of the stress working variation of a particule moving through the solid. The most important result is: the resultant of all the defect forces included in a volume V is the J integral on the surface surrounding V and the moment resultant is the L integral. So these integrals are defined without any assumption on the material constitutive equation. Another result is the material form of the virtual work principle - defect forces are acting like conventional forces in the conventional principles of virtual work. This lead to the introduction of the energy momentum tensor and of the associated couple stress. Application of this method is made to fracture mechanics in studying the defect forces distribution around a crack [fr

  3. Defective pyrite (100) surface: An ab initio study

    International Nuclear Information System (INIS)

    Stirling, Andras; Bernasconi, Marco; Parrinello, Michele

    2007-01-01

    The structural and electronic properties of sulfur monomeric defects at the FeS 2 (100) surface have been studied by periodic density-functional calculations. We have shown that for a monomeric sulfur bound to an originally fivefold coordinated surface Fe site, the defect core features a triplet electronic ground state with unpaired spins localized on the exposed Fe-S unit. At this site, the iron and sulfur ions have oxidation states +4 and -2, respectively. This defect can be seen as produced via heterolytic bond breaking of the S-S sulfur dimer followed by a Fe-S redox reaction. The calculated sulfur 2p core-level shifts of the monomeric defects are in good agreement with experimental photoemission spectra, which allow a compelling assignment of the different spectroscopic features. The effect of water on the stability of the defective surface has also been studied, and it has been shown that the triplet state is stable against the wetting of the surface. The most important implications of the presence of the monomeric sulfur defect on the reactivity are also discussed

  4. Defect assessment benchmark studies

    International Nuclear Information System (INIS)

    Hooton, D.G.; Sharples, J.K.

    1995-01-01

    Assessments of the resistance to fast fracture of the beltline region of a PWR vessel subjected to a pressurized thermal shock (PTS) transient have been carried out using the procedures of French (RCC-M) and German (KTA) design codes, and comparisons made with results obtained using the R6 procedure as applied for Sizewell B. The example chosen for these comparisons is of a generic nature, and is taken as the PTS identified by the Hirsch addendum to the Second Marshall report (1987) as the most severe transient with regard to vessel integrity. All assessment methods show the beltline region of the vessel to be safe from the risk of fast fracture, but by varying factors of safety. These factors are discussed in terms of margins between limiting and reference defect sizes, fracture toughness and stress intensity factor, and material temperature and temperature at the onset of upper-shelf materials behaviour. Based on these studies, consideration is given to issues involved in the harmonization of those sections of the design codes which are concerned with methods for the demonstration of the avoidance of the risk of failure by fast fracture. (author)

  5. A Brazing Defect Detection Using an Ultrasonic Infrared Imaging Inspection

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jai Wan; Choi, Young Soo; Jung, Seung Ho; Jung, Hyun Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2007-10-15

    When a high-energy ultrasound propagates through a solid body that contains a crack or a delamination, the two faces of the defect do not ordinarily vibrate in unison, and dissipative phenomena such as friction, rubbing and clapping between the faces will convert some of the vibrational energy to heat. By combining this heating effect with infrared imaging, one can detect a subsurface defect in material in real time. In this paper a realtime detection of the brazing defect of thin Inconel plates using the UIR (ultrasonic infrared imaging) technology is described. A low frequency (23 kHz) ultrasonic transducer was used to infuse the welded Inconel plates with a short pulse of sound for 280 ms. The ultrasonic source has a maximum power of 2 kW. The surface temperature of the area under inspection is imaged by an infrared camera that is coupled to a fast frame grabber in a computer. The hot spots, which are a small area around the bound between the two faces of the Inconel plates near the defective brazing point and heated up highly, are observed. And the weak thermal signal is observed at the defect position of brazed plate also. Using the image processing technology such as background subtraction average and image enhancement using histogram equalization, the position of defective brazing regions in the thin Inconel plates can be located certainly

  6. Neutron cross sections for defect production by high energy displacement cascades in copper

    International Nuclear Information System (INIS)

    Heinisch, H.L.; Mann, F.M.

    1984-01-01

    Defect production cross sections for copper have been devised, based on computer simulations of displacement cascades. One thousand cascades ranging in energy from 200 eV to 200 keV were generated with the MARLOWE computer code. The cascades were subjected to a semi-empirical cascade quenching procedure and to short-term annealing with the ALSOME computer code. Functions were fitted to the numbers of defects produced as a function of primary knock-on atom (PKA) damage energy for the following defect types: 1) the total number of point defects after quenching and after short-term annealing, 2) the numbers of free interstitials and free vacancies after short-term annealing, and 3) the numbers and sizes of vacancy and interstitial clusters after short-term annealing. In addition, a function describing the number of distinct damage regions (lobes) per cascade was fitted to results of a graphical analysis of the cascade configurations. The defect production functions have been folded into PKA spectra using the NJOY nuclear data processing code system with ENDF/B-V nuclear data to yield neutron cross sections for defect production in copper. The free vacancy cross section displays much less variation with neutron energy than the cross sections for damage energy or total point defects. (orig.)

  7. Serine biosynthesis and transport defects.

    Science.gov (United States)

    El-Hattab, Ayman W

    2016-07-01

    l-serine is a non-essential amino acid that is biosynthesized via the enzymes phosphoglycerate dehydrogenase (PGDH), phosphoserine aminotransferase (PSAT), and phosphoserine phosphatase (PSP). Besides its role in protein synthesis, l-serine is a potent neurotrophic factor and a precursor of a number of essential compounds including phosphatidylserine, sphingomyelin, glycine, and d-serine. Serine biosynthesis defects result from impairments of PGDH, PSAT, or PSP leading to systemic serine deficiency. Serine biosynthesis defects present in a broad phenotypic spectrum that includes, at the severe end, Neu-Laxova syndrome, a lethal multiple congenital anomaly disease, intermediately, infantile serine biosynthesis defects with severe neurological manifestations and growth deficiency, and at the mild end, the childhood disease with intellectual disability. A serine transport defect resulting from deficiency of the ASCT1, the main transporter for serine in the central nervous system, has been recently described in children with neurological manifestations that overlap with those observed in serine biosynthesis defects. l-serine therapy may be beneficial in preventing or ameliorating symptoms in serine biosynthesis and transport defects, if started before neurological damage occurs. Herein, we review serine metabolism and transport, the clinical, biochemical, and molecular aspects of serine biosynthesis and transport defects, the mechanisms of these diseases, and the potential role of serine therapy. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Evaluation of Bending Strength of Carburized Gears Based on Inferential Identification of Principal Surface Layer Defects

    Science.gov (United States)

    Masuyama, Tomoya; Inoue, Katsumi; Yamanaka, Masashi; Kitamura, Kenichi; Saito, Tomoyuki

    High load capacity of carburized gears originates mainly from the hardened layer and induced residual stress. On the other hand, surface decarburization, which causes a nonmartensitic layer, and inclusions such as oxides and segregation act as latent defects which considerably reduce fatigue strength. In this connection, the authors have proposed a formula of strength evaluation by separately quantifying defect influence. However, the principal defect which limits strength of gears with several different defects remains unclarified. This study presents a method of inferential identification of principal defects based on test results of carburized gears made of SCM420 clean steel, gears with both an artificial notch and nonmartensitic layer at the tooth fillet, and so forth. It clarifies practical uses of presented methods, and strength of carburized gears can be evaluated by focusing on principal defect size.

  9. Defect detection based on extreme edge of defective region histogram

    Directory of Open Access Journals (Sweden)

    Zouhir Wakaf

    2018-01-01

    Full Text Available Automatic thresholding has been used by many applications in image processing and pattern recognition systems. Specific attention was given during inspection for quality control purposes in various industries like steel processing and textile manufacturing. Automatic thresholding problem has been addressed well by the commonly used Otsu method, which provides suitable results for thresholding images based on a histogram of bimodal distribution. However, the Otsu method fails when the histogram is unimodal or close to unimodal. Defects have different shapes and sizes, ranging from very small to large. The gray-level distributions of the image histogram can vary between unimodal and multimodal. Furthermore, Otsu-revised methods, like the valley-emphasis method and the background histogram mode extents, which overcome the drawbacks of the Otsu method, require preprocessing steps and fail to use the general threshold for multimodal defects. This study proposes a new automatic thresholding algorithm based on the acquisition of the defective region histogram and the selection of its extreme edge as the threshold value to segment all defective objects in the foreground from the image background. To evaluate the proposed defect-detection method, common standard images for experimentation were used. Experimental results of the proposed method show that the proposed method outperforms the current methods in terms of defect detection.

  10. Piezoelectricity induced defect modes for shear waves in a periodically stratified supperlattice

    Science.gov (United States)

    Piliposyan, Davit

    2018-01-01

    Properties of shear waves in a piezoelectric stratified periodic structure with a defect layer are studied for a superlattice with identical piezoelectric materials in a unit cell. Due to the electro-mechanical coupling in piezoelectric materials the structure exhibits defect modes in the superlattice with full transmission peaks both for full contact and electrically shorted interfaces. The results show an existence of one or two transmission peaks depending on the interfacial conditions. In the long wavelength region where coupling between electro-magnetic and elastic waves creates frequency band gaps the defect layer introduces one or two defect modes transmitting both electro-magnetic and elastic energies. Other parameters affecting the defect modes are the thickness of the defect layer, differences in refractive indexes and the magnitude of the angle of the incident wave. The results of the paper may be useful in the design of narrow band filters or multi-channel piezoelectric filters.

  11. Oxidative stress

    Directory of Open Access Journals (Sweden)

    Stevanović Jelka

    2012-01-01

    Full Text Available The unceasing need for oxygen is in contradiction to the fact that it is in fact toxic to mammals. Namely, its monovalent reduction can have as a consequence the production of short-living, chemically very active free radicals and certain non-radical agents (nitrogen-oxide, superoxide-anion-radicals, hydroxyl radicals, peroxyl radicals, singlet oxygen, peroxynitrite, hydrogen peroxide, hypochlorous acid, and others. There is no doubt that they have numerous positive roles, but when their production is stepped up to such an extent that the organism cannot eliminate them with its antioxidants (superoxide-dismutase, glutathione-peroxidase, catalase, transferrin, ceruloplasmin, reduced glutathion, and others, a series of disorders is developed that are jointly called „oxidative stress.“ The reactive oxygen species which characterize oxidative stress are capable of attacking all main classes of biological macromolecules, actually proteins, DNA and RNA molecules, and in particular lipids. The free radicals influence lipid peroxidation in cellular membranes, oxidative damage to DNA and RNA molecules, the development of genetic mutations, fragmentation, and the altered function of various protein molecules. All of this results in the following consequences: disrupted permeability of cellular membranes, disrupted cellular signalization and ion homeostasis, reduced or loss of function of damaged proteins, and similar. That is why the free radicals that are released during oxidative stress are considered pathogenic agents of numerous diseases and ageing. The type of damage that will occur, and when it will take place, depends on the nature of the free radicals, their site of action and their source. [Projekat Ministarstva nauke Republike Srbije, br. 173034, br. 175061 i br. 31085

  12. Influence of damages caused by surface defects upon the oxydation mechanism of inconel 600

    International Nuclear Information System (INIS)

    Rousselet, J.M.; Moulin, G.; Huntz, A.M.

    1985-01-01

    The influence of thermochemical and mechanical treatments on the oxidation mechanism of Ni 76 Cr 16 Fe 8 alloys (Inconel 600) was studied from a kinetic and analytical point of view, in order to clarify the role of defects either due to a prestrain or related to impurities such as S, C. for example to overcome sulfur pollution of steam generator tubes of nuclear power plant. For unstrained alloys, the oxidation process is controlled by the diffusion of alloy elements in the metallic substrate. But, beyond a critical strain value, the diffusion rate in the alloy is sufficiently accelerated by the strain induced defects to involve an oxidation control by the diffusion of base-elements (Cr, Ni, Fe) in the oxide scale. Sulfides present in the alloy (due to a pre-sulphidation treatment) strongly accelerate the oxidation kinetics owing to the fact that a first oxidation step, controlled by a chemical process of sulphide decomposition, takes place simultaneously to an internal oxidation; then, a second step related to sulphur diffusion through the oxide scale appears; sulphur in the oxide scale creates defects which accelerate cationic diffusion in the oxides. The baneful influence of sulphur can be balanced by prestraining the material [fr

  13. Buried oxide layer in silicon

    Science.gov (United States)

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2001-01-01

    A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

  14. Facts about Congenital Heart Defects

    Science.gov (United States)

    ... types of CHDs. The types marked with a star (*) are considered critical CHDs. Atrial Septal Defect Atrioventricular ... for Disease Control and Prevention Email Recommend Tweet YouTube Instagram Listen Watch RSS ABOUT About CDC Jobs ...

  15. Birth Defects Data and Statistics

    Science.gov (United States)

    ... Submit" /> Information For… Media Policy Makers Data & Statistics Recommend on Facebook Tweet Share Compartir On This ... and critical. Read below for the latest national statistics on the occurrence of birth defects in the ...

  16. Defects in semiconductors

    International Nuclear Information System (INIS)

    Tilly, L.

    1993-04-01

    In this thesis, experimental results of the transition metals Ti, V, Nb, Mo, and W as impurity centres in silicon are presented. Transition metal doping was accomplished by ion implantation. Emphasis is put on energy level position, electrical and optical properties of the encountered defect levels. Junction space charge methods (JSCM) such as DLTS, photocapacitance and photocurrent techniques are employed. Three energy levels are found for the 3d-transition metals Ti(E c -0.06eV, E c -0.30eV, E v +0.26) and V(E c -0.21eV, E c -0,48e, E v +0.36eV), and for the 4d-element Nb(E c -0.29eV, E c -0.58eV, E v +0.163eV) in Silicon, whereas only one transition metal induced level is found for Mo(E v +0.30eV) and W(E v +0.38eV) respectively. Electrical and optical characteristics of Si 1-x Ge x ,0.7 7 cm -2 . The solvent Bi, used in the LPE-process, is found to be the dominant impurity element. Furthermore, liquid phase epitaxy of high purity In 0.53 Ga 0.57 As on InP, together with the properties of the Cu-induced acceptor in this material are examined. Free electron concentrations of n=5x10 14 cm -3 and electron Hall-mobilities of μ 77K = 44000 cm 2 /Vs are achieved. The energy level position of the Cu-acceptor is found to be E v +0.025eV. Photoluminescence and Hall-effect measurements, together with JSCM are the main characterization methods used. The band linups of In 0.53 Ga 0.47 As with GaAs and with InP are determined according to the Cu-acceptor energy level position in these materials. Additionally, the hydrostatic pressure dependence of the Cu-acceptor energy level position in In 0.53 Ga 0.47 As is examined. (103 refs.)

  17. PREFACE: Semiconducting oxides Semiconducting oxides

    Science.gov (United States)

    Catlow, Richard; Walsh, Aron

    2011-08-01

    Semiconducting oxides are amongst the most widely studied and topical materials in contemporary condensed matter science, with interest being driven both by the fundamental challenges posed by their electronic and magnetic structures and properties, and by the wide range of applications, including those in catalysis and electronic devices. This special section aims to highlight recent developments in the physics of these materials, and to show the link between developing fundamental understanding and key application areas of oxide semiconductors. Several aspects of the physics of this wide and expanding range of materials are explored in this special section. Transparent semiconducting oxides have a growing role in several technologies, but challenges remain in understanding their electronic structure and the physics of charge carriers. A related problem concerns the nature of redox processes and the reactions which interconvert defects and charge carriers—a key issue which may limit the extent to which doping strategies may be used to alter electronic properties. The magnetic structures of the materials pose several challenges, while surface structures and properties are vital in controlling catalytic properties, including photochemical processes. The field profits from and exploits a wide range of contemporary physical techniques—both experimental and theoretical. Indeed, the interplay between experiment and computation is a key aspect of contemporary work. A number of articles describe applications of computational methods whose use, especially in modelling properties of defects in these materials, has a long and successful history. Several papers in this special section relate to work presented at a symposium within the European Materials Research Society (EMRS) meeting held in Warsaw in September 2010, and we are grateful to the EMRS for supporting this symposium. We would also like to thank the editorial staff of Journal of Physics: Condensed Matter for

  18. Topological defects from the multiverse

    Science.gov (United States)

    Zhang, Jun; Blanco-Pillado, Jose J.; Garriga, Jaume; Vilenkin, Alexander

    2015-05-01

    Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to be quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly enhanced in the case where the cosmological constant of our parent vacuum is much higher than the vacuum energy density during inflation in our bubble.

  19. Topological defects from the multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Blanco-Pillado, Jose J. [Department of Theoretical Physics, University of the Basque Country UPV/EHU, 48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, 48013, Bilbao (Spain); Garriga, Jaume [Departament de Fisica Fonamental i Institut de Ciencies del Cosmos, Universitat de Barcelona, Marti i Franques, 1, 08028, Barcelona (Spain); Vilenkin, Alexander [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States)

    2015-05-28

    Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to be quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly enhanced in the case where the cosmological constant of our parent vacuum is much higher than the vacuum energy density during inflation in our bubble.

  20. Topological defects from the multiverse

    International Nuclear Information System (INIS)

    Zhang, Jun; Vilenkin, Alexander; Blanco-Pillado, Jose J.; Garriga, Jaume

    2015-01-01

    Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to be quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly enhanced in the case where the cosmological constant of our parent vacuum is much higher than the vacuum energy density during inflation in our bubble

  1. Electrical fingerprint of pipeline defects

    International Nuclear Information System (INIS)

    Mica, Isabella; Polignano, Maria Luisa; Marco, Cinzia De

    2004-01-01

    Pipeline defects are dislocations that connect the source region of the transistor with the drain region. They were widely reported to occur in CMOS, BiCMOS devices and recently in SOI technologies. They can reduce device yield either by affecting the devices functionality or by increasing the current consumption under stand-by conditions. In this work the electrical fingerprint of these dislocations is studied, its purpose is to enable us to identify these defects as the ones responsible for device failure. It is shown that the pipeline defects are responsible for a leakage current from source to drain in the transistors. This leakage has a resistive characteristic and it is lightly modulated by the body bias. It is not sensitive to temperature; vice versa the off-current of a good transistor exhibits the well-known exponential dependence on 1/T. The emission spectrum of these defects was studied and compared with the spectrum of a good transistor. The paper aims to show that the spectrum of a defective transistor is quite peculiar; it shows well defined peaks, whereas the spectrum of a good transistor under saturation conditions is characterized by a broad spectral light emission distribution. Finally the deep-level transient spectroscopy (DLTS) is tried on defective diodes

  2. Point defects and transport properties in carbides

    International Nuclear Information System (INIS)

    Matzke, Hj.

    1984-01-01

    Carbides of transition metals and of actinides are interesting and technologically important. The transition-metal carbides (or carbonitrides) are extensively being used as hard materials and some of them are of great interest because of the high transition temperature for superconductivity, e.g. 17 K for Nb(C,N). Actinide carbides and carbonitrides, (U,Pu)C and (U,Pu)(C,N) are being considered as promising advanced fuels for liquid metal cooled fast breeder nuclear reactors. Basic interest exists in all these materials because of their high melting points (e.g. 4250 K for TaC) and the unusually broad range of homogeneity of nonstoichiometric compositions (e.g. from UCsub(0.9) to UCsub(1.9) at 2500 K). Interaction of point defects to clusters and short-range ordering have recently been studied with elastic neutron diffraction and diffuse scattering techniques, and calculations of energies of formation and interaction of point defects became available for selected carbides. Diffusion measurements also exist for a number of carbides, in particular for the actinide carbides. The existing knowledge is discussed and summarized with emphasis on informative examples of particular technological relevance. (Auth.)

  3. Natural short sleeper

    Science.gov (United States)

    Sleep - natural short sleeper ... 7 to 9 hours of sleep each night. Short sleepers sleep less than 75% of what is normal for their age. Natural short sleepers are different from people who chronically do ...

  4. Short stature caused by isolated SHOX gene haploinsufficiency: update on the diagnosis and treatment.

    Science.gov (United States)

    Jorge, Alexander A L; Funari, Mariana Fa; Nishi, Mirian Y; Mendonca, Berenice B

    2010-12-01

    Heterozygous SHOX defects are observed in about 50 to 90% of patients with Leri-Weill dyschondrosteosis (LWD), a common dominant inherited skeletal dysplasia; and in 2 to 15% of children with idiopathic short stature (ISS), indicating that SHOX defects are the most important monogenetic cause of short stature. In addition, children selected by disproportionate idiopathic short stature had a higher frequency of SHOX mutations (22%). A careful clinical evaluation of family members with short stature is recommended since it usually revealed LWD patients in families first classified as having ISS or familial short stature. SHOX-molecular analysis is indicated in families with LWD and ISS children with disproportionate short stature. Treatment with recombinant human growth hormone is considered an accepted approach to treat short stature associated with isolated SHOX defect. Here we review clinical, molecular and therapeutic aspects of SHOX haploinsufficiency.

  5. Photoluminescence as a tool for characterizing point defects in semiconductors

    Science.gov (United States)

    Reshchikov, Michael

    2012-02-01

    Photoluminescence is one of the most powerful tools used to study optically-active point defects in semiconductors, especially in wide-bandgap materials. Gallium nitride (GaN) and zinc oxide (ZnO) have attracted considerable attention in the last two decades due to their prospects in optoelectronics applications, including blue and ultraviolet light-emitting devices. However, in spite of many years of extensive studies and a great number of publications on photoluminescence from GaN and ZnO, only a few defect-related luminescence bands are reliably identified. Among them are the Zn-related blue band in GaN, Cu-related green band and Li-related orange band in ZnO. Numerous suggestions for the identification of other luminescence bands, such as the yellow band in GaN, or green and yellow bands in ZnO, do not stand up under scrutiny. In these conditions, it is important to classify the defect-related luminescence bands and find their unique characteristics. In this presentation, we will review the origin of the major luminescence bands in GaN and ZnO. Through simulations of the temperature and excitation intensity dependences of photoluminescence and by employing phenomenological models we are able to obtain important characteristics of point defects such as carrier capture cross-sections for defects, concentrations of defects, and their charge states. These models are also used to find the absolute internal quantum efficiency of photoluminescence and obtain information about nonradiative defects. Results from photoluminescence measurements will be compared with results of the first-principle calculations, as well as with the experimental data obtained by other techniques such as positron annihilation spectroscopy, deep-level transient spectroscopy, and secondary ion mass spectrometry.

  6. Dual approaches for defects condensation

    Energy Technology Data Exchange (ETDEWEB)

    Rougemont, Romulo; Grigorio, Leonardo de Souza; Wotzasek, Clovis [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Guimaraes, Marcelo Santos [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)

    2009-07-01

    Full text. Due to the fact that the QCD running coupling constant becomes larger as we go into the low energy (or large distance) limit of the theory, a perturbative treatment of its infrared (IR) region is impossible. In particular, a formal mathematical demonstration of color confinement and a complete physical understanding of the exact mechanism that confines quarks and gluons are two missing points in our current knowledge of the IR-QCD. It was known that due to the Meissner effect of expulsion of magnetic fields in a electric condensate that usual superconductors should confine magnetic monopoles. That point led to the conjecture that the QCD vacuum could be a condensate of chromomagnetic monopoles, a dual superconductor (DSC). Such a chromomagnetic condensate should be responsible for the dual Meissner effect which is expected to lead to the confinement of color charges immersed in this medium. In dual superconductor models of color confinement, magnetic monopoles appear as topological defects in points of the space where the abelian projection becomes singular. Also, condensation of other kinds of defects such as vortices in superfluids and line-like defects in solids are responsible for a great variety of phase transitions, which once more proves the relevance of the subject. In the present work we review two methods that allow us to approach the condensation of defects: the Kleinert Mechanism (KM) and the Julia-Toulouse Mechanism (JTM). We show that in the limit where the vortex gauge field goes to zero, which we identify as the signature of the condensation of defects in the dual picture, these are two equivalent dual prescriptions for obtaining an effective theory for a phase where defects are condensed, starting from the fundamental theory defined in the normal phase where defects are diluted. (author)

  7. Compact Models for Defect Diffusivity in Semiconductor Alloys.

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Alan F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanostructure Physics Department; Modine, Normand A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanostructure Physics Department; Lee, Stephen R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Materials Sciences Department; Foiles, Stephen M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Computational Materials and Data Science Department

    2017-09-01

    Predicting transient effects caused by short - pulse neutron irradiation of electronic devices is an important part of Sandia's mission. For example , predicting the diffusion of radiation - induced point defects is needed with in Sandia's Qualification Alternative to the Sandia Pulsed Reactor (QASPR) pro gram since defect diffusion mediates transient gain recovery in QASPR electronic devices. Recently, the semiconductors used to fabricate radiation - hard electronic devices have begun to shift from silicon to III - V compounds such as GaAs, InAs , GaP and InP . An advantage of this shift is that it allows engineers to optimize the radiation hardness of electronic devices by using alloy s such as InGaAs and InGaP . However, the computer codes currently being used to simulate transient radiation effects in QASP R devices will need to be modified since they presume that defect properties (charge states, energy levels, and diffusivities) in these alloys do not change with time. This is not realistic since the energy and properties of a defect depend on the types of atoms near it and , therefore, on its location in the alloy. In particular, radiation - induced defects are created at nearly random locations in an alloy and the distribution of their local environments - and thus their energies and properties - evolves with time as the defects diffuse through the alloy . To incorporate these consequential effects into computer codes used to simulate transient radiation effects, we have developed procedures to accurately compute the time dependence of defect energies and properties and then formulate them within compact models that can be employed in these computer codes. In this document, we demonstrate these procedures for the case of the highly mobile P interstitial (I P ) in an InGaP alloy. Further dissemination only as authorized to U.S. Government agencies and their contractors; other requests shall be approved by the originating facility or higher DOE

  8. Pathophysiology of Corneal Scarring in Persistent Epithelial Defects After PRK and Other Corneal Injuries.

    Science.gov (United States)

    Wilson, Steven E; Medeiros, Carla S; Santhiago, Marcony R

    2018-01-01

    To analyze corneal persistent epithelial defects that occurred at 3 to 4 weeks after -4.50 diopter (D) photorefractive keratectomy (PRK) in rabbits and apply this pathophysiology to the treatment of persistent epithelial defects that occur after any corneal manipulations or diseases. Two of 168 corneas that had -4.50 D PRK to study epithelial basement membrane regeneration developed spontaneous persistent epithelial defects that did not heal at 3 weeks after PRK. These were studied with slit-lamp photographs, immunohistochemistry for the myofibroblast marker alpha-smooth muscle actin (α-SMA), and transmission electron microscopy. Myofibroblasts developed at the stromal surface within the persistent epithelial defect and for a short distance peripheral to the leading edge of the epithelium. No normal epithelial basement membrane was detectable within the persistent epithelial defect or for up to 0.3 mm behind the leading edge of the epithelium, although epithelial basement membrane had normally regenerated in other areas of the zone ablated by an excimer laser where the epithelium healed promptly. A persistent epithelial defect in the cornea results in the development of myofibroblasts and disordered extracellular matrix produced by these cells that together cause opacity within, and a short distance beyond, the persistent epithelial defect. Clinicians should treat persistent epithelial defects within 10 days of non-closure of the epithelium to facilitate epithelial healing to prevent long-term stromal scarring (fibrosis). [J Refract Surg. 2018;34(1):59-64.]. Copyright 2018, SLACK Incorporated.

  9. Defecto en la homeostasis del óxido nítrico: Mecanismo común subyacente de la insulino-resistencia, la hiperactividad simpática y la morbi-mortalidad cardiovascular Defective nitric oxide homeostasis: Common underlying mechanism between insulin resistance, sympathetic overactivity and cardiovascular morbidity and mortality

    Directory of Open Access Journals (Sweden)

    Marcos Schwab

    2008-06-01

    Full Text Available La incidencia de la obesidad y de la resistencia a la insulina con sus complicaciones asociadas, como la hipertensión arterial y el aumento de la morbi-mortalidad cardiovascular, alcanzan hoy en día proporciones epidémicas y representan un problema mayor de salud pública. En los últimos años se ha demostrado que la administración de insulina, además de sus efectos metabólicos, posee efectos cardiovasculares importantes. El sistema nervioso simpático y el sistema L-arginina - óxido nítrico son los mediadores centrales de estas acciones cardiovasculares de la insulina. Mostramos, gracias a estudios realizados en animales y en humanos, que no sólo un déficit de la síntesis del óxido nítrico (NO, sino también un aumento exagerado en su producción representan un defecto subyacente central de las anomalías metabólicas, cardiovasculares y del sistema nervioso simpático que caracterizan a la insulino resistencia. Mostramos cómo estos resultados establecen el fundamento científico para la utilización de sustancias farmacológicas capaces de liberar de manera prolongada cantidades fisiológicas de NO o de inhibidores de su sobreproducción como futuros tratamientos para la resistencia a la insulina y sus complicaciones asociadas.Obesity, insulin resistance and associated cardiovascular complications are reaching epidemic proportions worldwide and represent a major public health problem. Over the past decade, evidence has accumulated indicating that insulin administration, in addition to its metabolic effects, also has important cardiovascular actions. The sympathetic nervous system and the L-arginine-nitric oxide pathway are the central players in the mediation of insulin's cardiovascular actions. Based on recent animal and human research, we demonstrate that both defective and augmented NO synthesis represent a central defect triggering many of the metabolic, vascular and sympathetic abnormalities characteristic of insulin

  10. Determination of defect content and defect profile in semiconductor heterostructures

    International Nuclear Information System (INIS)

    Zubiaga, A; Garcia, J A; Plazaola, F; Zuniga-Perez, J; Munoz-Sanjose, V

    2011-01-01

    In this article we present an overview of the technique to obtain the defects depth profile and width of a deposited layer and multilayer based on positron annihilation spectroscopy. In particular we apply the method to ZnO and ZnO/ZnCdO layers deposited on sapphire substrates. After introducing some terminology we first calculate the trend that the W/S parameters of the Doppler broadening measurements must follow, both in a qualitative and quantitative way. From this point we extend the results to calculate the width and defect profiles in deposited layer samples.

  11. Determination of defect content and defect profile in semiconductor heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zubiaga, A [Laboratory of Physics, HUT, PO Box 1100, 02015 TKK, Espoo (Finland); Garcia, J A; Plazaola, F [Zientzia eta Teknologia Fakultatea, Euskal Herriko Unbertsitatea, P. K. 644, 48080, Bilbao (Spain); Zuniga-Perez, J; Munoz-Sanjose, V, E-mail: fernando.plazaola@ehu.es [Universitat de Valencia, Departamento de Fisica Aplicada i Electromagnetisme, Dr. Moliner 50, 46100 Burjassot, Valencia (Spain)

    2011-01-10

    In this article we present an overview of the technique to obtain the defects depth profile and width of a deposited layer and multilayer based on positron annihilation spectroscopy. In particular we apply the method to ZnO and ZnO/ZnCdO layers deposited on sapphire substrates. After introducing some terminology we first calculate the trend that the W/S parameters of the Doppler broadening measurements must follow, both in a qualitative and quantitative way. From this point we extend the results to calculate the width and defect profiles in deposited layer samples.

  12. Defects in conformal field theory

    International Nuclear Information System (INIS)

    Billò, Marco; Gonçalves, Vasco; Lauria, Edoardo; Meineri, Marco

    2016-01-01

    We discuss consequences of the breaking of conformal symmetry by a flat or spherical extended operator. We adapt the embedding formalism to the study of correlation functions of symmetric traceless tensors in the presence of the defect. Two-point functions of a bulk and a defect primary are fixed by conformal invariance up to a set of OPE coefficients, and we identify the allowed tensor structures. A correlator of two bulk primaries depends on two cross-ratios, and we study its conformal block decomposition in the case of external scalars. The Casimir equation in the defect channel reduces to a hypergeometric equation, while the bulk channel blocks are recursively determined in the light-cone limit. In the special case of a defect of codimension two, we map the Casimir equation in the bulk channel to the one of a four-point function without defect. Finally, we analyze the contact terms of the stress-tensor with the extended operator, and we deduce constraints on the CFT data. In two dimensions, we relate the displacement operator, which appears among the contact terms, to the reflection coefficient of a conformal interface, and we find unitarity bounds for the latter.

  13. Defects in conformal field theory

    Energy Technology Data Exchange (ETDEWEB)

    Billò, Marco [Dipartimento di Fisica, Università di Torino, and Istituto Nazionale di Fisica Nucleare - sezione di Torino,Via P. Giuria 1 I-10125 Torino (Italy); Gonçalves, Vasco [Centro de Física do Porto,Departamento de Física e Astronomia Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); ICTP South American Institute for Fundamental Research Instituto de Física Teórica,UNESP - University Estadual Paulista,Rua Dr. Bento T. Ferraz 271, 01140-070, São Paulo, SP (Brazil); Lauria, Edoardo [Institute for Theoretical Physics, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Meineri, Marco [Perimeter Institute for Theoretical Physics,Waterloo, Ontario, N2L 2Y5 (Canada); Scuola Normale Superiore, and Istituto Nazionale di Fisica Nucleare - sezione di Pisa,Piazza dei Cavalieri 7 I-56126 Pisa (Italy)

    2016-04-15

    We discuss consequences of the breaking of conformal symmetry by a flat or spherical extended operator. We adapt the embedding formalism to the study of correlation functions of symmetric traceless tensors in the presence of the defect. Two-point functions of a bulk and a defect primary are fixed by conformal invariance up to a set of OPE coefficients, and we identify the allowed tensor structures. A correlator of two bulk primaries depends on two cross-ratios, and we study its conformal block decomposition in the case of external scalars. The Casimir equation in the defect channel reduces to a hypergeometric equation, while the bulk channel blocks are recursively determined in the light-cone limit. In the special case of a defect of codimension two, we map the Casimir equation in the bulk channel to the one of a four-point function without defect. Finally, we analyze the contact terms of the stress-tensor with the extended operator, and we deduce constraints on the CFT data. In two dimensions, we relate the displacement operator, which appears among the contact terms, to the reflection coefficient of a conformal interface, and we find unitarity bounds for the latter.

  14. Investigation of the crystal lattice defects by means of the positrons annihilations; Badania defektow sieci krystalicznej metoda anihilacji pozytonow

    Energy Technology Data Exchange (ETDEWEB)

    Dryzek, J [Institute of Nuclear Physics, Cracow (Poland)

    1994-12-31

    In this report the positrons annihilation methods as a tool for the crystal defects studies is presented. The short description of the positron - crystal interactions and different positron capture models are discussed. 192 refs, 67 figs, 6 tabs.

  15. Detection of paint polishing defects

    Science.gov (United States)

    Rebeggiani, S.; Wagner, M.; Mazal, J.; Rosén, B.-G.; Dahlén, M.

    2018-06-01

    Surface finish plays a major role on perceived product quality, and is the first thing a potential buyer sees. Today end-of-line repairs of the body of cars and trucks are inevitably to secure required surface quality. Defects that occur in the paint shop, like dust particles, are eliminated by manual sanding/polishing which lead to other types of defects when the last polishing step is not performed correctly or not fully completed. One of those defects is known as ‘polishing roses’ or holograms, which are incredibly hard to detect in artificial light but are clearly visible in sunlight. This paper will present the first tests with a measurement set-up newly developed to measure and analyse polishing roses. The results showed good correlations to human visual evaluations where repaired panels were estimated based on the defects’ intensity, severity and viewing angle.

  16. Theory of Defects in Semiconductors

    CERN Document Server

    Drabold, David A

    2007-01-01

    Semiconductor science and technology is the art of defect engineering. The theoretical modeling of defects has improved dramatically over the past decade. These tools are now applied to a wide range of materials issues: quantum dots, buckyballs, spintronics, interfaces, amorphous systems, and many others. This volume presents a coherent and detailed description of the field, and brings together leaders in theoretical research. Today's state-of-the-art, as well as tomorrow’s tools, are discussed: the supercell-pseudopotential method, the GW formalism,Quantum Monte Carlo, learn-on-the-fly molecular dynamics, finite-temperature treatments, etc. A wealth of applications are included, from point defects to wafer bonding or the propagation of dislocation.

  17. Defect CFTs and holographic multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Fiol, Bartomeu, E-mail: bfiol@ub.edu [Departament de Física Fonamental i Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, 08193 Barcelona (Spain)

    2010-07-01

    We investigate some aspects of a recent proposal for a holographic description of the multiverse. Specifically, we focus on the implications on the suggested duality of the fluctuations of a bubble separating two universes with different cosmological constants. We do so by considering a similar problem in a 2+1 CFT with a codimension one defect, obtained by an M5-brane probe embedding in AdS{sub 4} × S{sup 7}, and studying its spectrum of fluctuations. Our results suggest that the kind of behavior required by the spectrum of bubble fluctuations is not likely to take place in defect CFTs with an AdS dual, although it might be possible if the defect supports a non-unitary theory.

  18. Defect CFTs and holographic multiverse

    International Nuclear Information System (INIS)

    Fiol, Bartomeu

    2010-01-01

    We investigate some aspects of a recent proposal for a holographic description of the multiverse. Specifically, we focus on the implications on the suggested duality of the fluctuations of a bubble separating two universes with different cosmological constants. We do so by considering a similar problem in a 2+1 CFT with a codimension one defect, obtained by an M5-brane probe embedding in AdS 4 × S 7 , and studying its spectrum of fluctuations. Our results suggest that the kind of behavior required by the spectrum of bubble fluctuations is not likely to take place in defect CFTs with an AdS dual, although it might be possible if the defect supports a non-unitary theory

  19. A study of process-related electrical defects in SOI lateral bipolar transistors fabricated by ion implantation

    Science.gov (United States)

    Yau, J.-B.; Cai, J.; Hashemi, P.; Balakrishnan, K.; D'Emic, C.; Ning, T. H.

    2018-04-01

    We report a systematic study of process-related electrical defects in symmetric lateral NPN transistors on silicon-on-insulator (SOI) fabricated using ion implantation for all the doped regions. A primary objective of this study is to see if pipe defects (emitter-collector shorts caused by locally enhanced dopant diffusion) are a show stopper for such bipolar technology. Measurements of IC-VCE and Gummel currents in parallel-connected transistor chains as a function of post-fabrication rapid thermal anneal cycles allow several process-related electrical defects to be identified. They include defective emitter-base and collector-base diodes, pipe defects, and defects associated with a dopant-deficient region in an extrinsic base adjacent its intrinsic base. There is no evidence of pipe defects being a major concern in SOI lateral bipolar transistors.

  20. Radiation annealing in cuprous oxide

    DEFF Research Database (Denmark)

    Vajda, P.

    1966-01-01

    Experimental results from high-intensity gamma-irradiation of cuprous oxide are used to investigate the annealing of defects with increasing radiation dose. The results are analysed on the basis of the Balarin and Hauser (1965) statistical model of radiation annealing, giving a square...