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Sample records for oxidation state analogs

  1. Quantum States Transfer by Analogous Bell States

    International Nuclear Information System (INIS)

    Mei Di; Li Chong; Yang Guohui; Song Heshan

    2008-01-01

    Transmitting quantum states by channels of analogous Bell states is studied in this paper. We analyze the transmitting process, constructed the probabilitic unitary operator, and gain the largest successful transfer quantum state probability.

  2. Study of oxidation states of the transition metals in a series of Prussian blue analogs using x-ray absorption near edge structure (XANES) spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Adak, S. [Department of Physics, New Mexico State University, Las Cruces, NM, 88003 (United States); Hartl, M., E-mail: monika.hartl@esss.se [European Spallation Source ESS AB, 22100, Lund (Sweden); Manuel Lujan Jr. Neutron Scattering Center (LANSCE-LC), Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States); Daemen, L. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN, 37830 (United States); Manuel Lujan Jr. Neutron Scattering Center (LANSCE-LC), Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States); Fohtung, E.; Nakotte, H. [Department of Physics, New Mexico State University, Las Cruces, NM, 88003 (United States)

    2017-01-15

    Highlights: • Systematic XANES measurements on Prussian blue analogs shows oxidation state of transition metals. • Cobal-iron bimetallic hexacyanometallates show unexpected oxidation states. • Iron(II) ions in hexacyanometallates(III) show varying spin state depending on their bond to the “N” end or “C” end of the cyanide ligand. • Thermal expansion coefficients have been linked to the XANES results. - Abstract: There have been renewed interests in metal-organic framework classes of materials such as Prussian blue analogues (PBAs) due to their potential usage in energy storage applications. In particular, due to their high surface areas, controllable structures and excellent electrochemical properties, PBAs such as hexacyanometalates M{sup II}{sub 3}[A{sup III}(CN){sub 6}]{sub 2*}nH{sub 2}O (M = Mn, Fe, Co, Ni, Cu, Zn; A = Co, Fe, Cr; n = no. of water molecules present), M{sup II}{sub 2}[Fe{sup II}(CN){sub 6}]{sub 2*}nH{sub 2}O (M = Mn, Co, Ni, Cu, Zn) and mixed hexacyanometalates(III) (Fe{sub 1-x}Co{sub x}){sub 3}[B{sup III}(CN){sub 6}]{sub 2}·nH{sub 2}O (x = 0.25, 0.5, 0.75; B = Co, Fe) could have possible usage as a new class of cathode and even anode materials for rechargeable batteries. Detailed knowledge of the oxidation states of the transition metals in PBAs is required to improve efficiency and durability of such devices. Furthermore, a link between the thermal expansion observed in these materials and the oxidation state of the transition metal is of interest to synthesize materials with a desired thermal expansion behavior, Here we demonstrate the use of Synchrotron based X-ray absorption near-edge structure (XANES) spectra to identify transition metal oxidation states. Our analysis reveals the presence of divalent, trivalent and/or mixed valence transition metals in the materials as well as high-spin and low-spin complexes.

  3. Symmetry energy II: Isobaric analog states

    Science.gov (United States)

    Danielewicz, Pawel; Lee, Jenny

    2014-02-01

    Using excitation energies to isobaric analog states (IAS) and charge invariance, we extract nuclear symmetry coefficients, representing a mass formula, on a nucleus-by-nucleus basis. Consistently with charge invariance, the coefficients vary weakly across an isobaric chain. However, they change strongly with nuclear mass and range from aa˜10 MeV at mass A˜10 to aa˜22 MeV at A˜240. Variation with mass can be understood in terms of dependence of nuclear symmetry energy on density and the rise in importance of low densities within nuclear surface in smaller systems. At A≳30, the dependence of coefficients on mass can be well described in terms of a macroscopic volume-surface competition formula with aaV≃33.2 MeV and aaS≃10.7 MeV. Our further investigation shows, though, that the fitted surface symmetry coefficient likely significantly underestimates that for the limit of half-infinite matter. Following the considerations of a Hohenberg-Kohn functional for nuclear systems, we determine how to find in practice the symmetry coefficient using neutron and proton densities, even when those densities are simultaneously affected by significant symmetry-energy and Coulomb effects. These results facilitate extracting the symmetry coefficients from Skyrme-Hartree-Fock (SHF) calculations, that we carry out using a variety of Skyrme parametrizations in the literature. For the parametrizations, we catalog novel short-wavelength instabilities. In our further analysis, we retain only those parametrizations which yield systems that are adequately stable both in the long- and short-wavelength limits. In comparing the SHF and IAS results for the symmetry coefficients, we arrive at narrow (±2.4 MeV) constraints on the symmetry-energy values S(ρ) at 0.04≲ρ≲0.13 fm. Towards normal density the constraints significantly widen, but the normal value of energy aaV and the slope parameter L are found to be strongly correlated. To narrow the constraints, we reach for the

  4. Foucault's Pendulum, Analog for an Electron Spin State

    Science.gov (United States)

    Linck, Rebecca

    2012-11-01

    The classical Lagrangian that describes the coupled oscillations of Foucault's pendulum presents an interesting analog to an electron's spin state in an external magnetic field. With a simple modification, this classical Lagrangian yields equations of motion that directly map onto the Schrodinger-Pauli Equation. This analog goes well beyond the geometric phase, reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.

  5. Microscopic description and excitation of unitary analog states

    Energy Technology Data Exchange (ETDEWEB)

    Kisslinger, L S [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA); Van Giai, N [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire

    1977-12-05

    A microscopic investigation in a self-consistent particle-hole model reveals approximate unitary analog states in spite of large symmetry breaking. The K-nucleus elastic scattering and (K/sup -/, ..pi../sup -/) excitation of these states are studied, showing strong surface effects.

  6. Acoustic analog of monolayer graphene and edge states

    International Nuclear Information System (INIS)

    Zhong, Wei; Zhang, Xiangdong

    2011-01-01

    Acoustic analog of monolayer graphene has been designed by using silicone rubber spheres of honeycomb lattices embedded in water. The dispersion of the structure has been studied theoretically using the rigorous multiple-scattering method. The energy spectra with the Dirac point have been verified and zigzag edge states have been found in ribbons of the structure, which are analogous to the electronic ones in graphene nanoribbons. The guided modes along the zigzag edge excited by a point source have been numerically demonstrated. The open cavity and 'Z' type edge waveguide with 60 o corners have also been realized by using such edge states. -- Highlights: → Acoustic analog of monolayer graphene has been designed. → The energy spectra with the Dirac point have been verified. → The zigzag edge states have been found in ribbons of the structure. → The guided modes excited by a point source have been demonstrated. → The open cavity and 'Z' type edge waveguide have been realized.

  7. Foucault's pendulum, a classical analog for the electron spin state

    Science.gov (United States)

    Linck, Rebecca A.

    Spin has long been regarded as a fundamentally quantum phenomena that is incapable of being described classically. To bridge the gap and show that aspects of spin's quantum nature can be described classically, this work uses a classical Lagrangian based on the coupled oscillations of Foucault's pendulum as an analog for the electron spin state in an external magnetic field. With this analog it is possible to demonstrate that Foucault's pendulum not only serves as a basis for explaining geometric phase, but is also a basis for reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured electron spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.

  8. Gaussian density matrices: Quantum analogs of classical states

    International Nuclear Information System (INIS)

    Mann, A.; Revzen, M.

    1993-01-01

    We study quantum analogs of clasical situations, i.e. quantum states possessing some specific classical attribute(s). These states seem quite generally, to have the form of gaussian density matrices. Such states can always be parametrized as thermal squeezed states (TSS). We consider the following specific cases: (a) Two beams that are built from initial beams which passed through a beam splitter cannot, classically, be distinguished from (appropriately prepared) two independent beams that did not go through a splitter. The only quantum states possessing this classical attribute are TSS. (b) The classical Cramer's theorem was shown to have a quantum version (Hegerfeldt). Again, the states here are Gaussian density matrices. (c) The special case in the study of the quantum version of Cramer's theorem, viz. when the state obtained after partial tracing is a pure state, leads to the conclusion that all states involved are zero temperature limit TSS. The classical analog here are gaussians of zero width, i.e. all distributions are δ functions in phase space. (orig.)

  9. Analog memory and spike-timing-dependent plasticity characteristics of a nanoscale titanium oxide bilayer resistive switching device

    International Nuclear Information System (INIS)

    Seo, Kyungah; Park, Sangsu; Lee, Kwanghee; Lee, Byounghun; Hwang, Hyunsang; Kim, Insung; Jung, Seungjae; Jo, Minseok; Park, Jubong; Shin, Jungho; Biju, Kuyyadi P; Kong, Jaemin

    2011-01-01

    We demonstrated analog memory, synaptic plasticity, and a spike-timing-dependent plasticity (STDP) function with a nanoscale titanium oxide bilayer resistive switching device with a simple fabrication process and good yield uniformity. We confirmed the multilevel conductance and analog memory characteristics as well as the uniformity and separated states for the accuracy of conductance change. Finally, STDP and a biological triple model were analyzed to demonstrate the potential of titanium oxide bilayer resistive switching device as synapses in neuromorphic devices. By developing a simple resistive switching device that can emulate a synaptic function, the unique characteristics of synapses in the brain, e.g. combined memory and computing in one synapse and adaptation to the outside environment, were successfully demonstrated in a solid state device.

  10. Utilizing multiple state variables to improve the dynamic range of analog switching in a memristor

    International Nuclear Information System (INIS)

    Jeong, YeonJoo; Kim, Sungho; Lu, Wei D.

    2015-01-01

    Memristors and memristive systems have been extensively studied for data storage and computing applications such as neuromorphic systems. To act as synapses in neuromorphic systems, the memristor needs to exhibit analog resistive switching (RS) behavior with incremental conductance change. In this study, we show that the dynamic range of the analog RS behavior can be significantly enhanced in a tantalum-oxide-based memristor. By controlling different state variables enabled by different physical effects during the RS process, the gradual filament expansion stage can be selectively enhanced without strongly affecting the abrupt filament length growth stage. Detailed physics-based modeling further verified the observed experimental effects and revealed the roles of oxygen vacancy drift and diffusion processes, and how the diffusion process can be selectively enhanced during the filament expansion stage. These findings lead to more desirable and reliable memristor behaviors for analog computing applications. Additionally, the ability to selectively control different internal physical processes demonstrated in the current study provides guidance for continued device optimization of memristor devices in general

  11. Population and particle decay of isobaric analog states in medium heavy nuclei

    International Nuclear Information System (INIS)

    Gales, S.

    1980-05-01

    The systematic features of proton stripping and neutron pick-up reactions to Isobaric Analog States in medium heavy nuclei are presented. The ( 3 He,d) reaction investigated at high incident energy is shown to selectively excite high-spin particle-analog states. Similarly the ( 3 He,α) reaction populates hole-analog states. The recent results related to such highly excited states in a wide range of nuclei ( 48 Ca to 208 Pb) are discussed in the framework of the DWBA theory of direct reactions with special emphasis on the treatment of unbound proton states or deeply-bound neutron hole states. The particle decay of Isobaric Analog States are investigated using the ( 3 He,d p) and ( 3 He, α p) sequential processes. The experimental method developed at Orsay (0 0 detection) for particle-particle angular correlations is presented. The advantage and the limits of such approach are illustrated by typical examples of particle decays: core-excited states, neutron particle-hole multiplets and the first observation of the proton emission of hole-analog levels. In conclusion new experimental approaches such as asymmetry measurements for analog states observed in transfer reactions or possible population of double analog states in heavy nuclei are discussed

  12. Control of analog ferroelectric states by small dc-bias in conjunction with fluctuating waveforms

    International Nuclear Information System (INIS)

    Ricinschi, Dan; Okuyama, Masanori

    2009-01-01

    In this paper we demonstrate several possibilities to create and control partially switched analog states of ferroelectric materials, from measurements on PZT capacitors. By employing various types of fluctuating waveforms and controlling the domain dynamics with dc bias of small intensities, we have shown that it is possible to generate sequences of analog ferroelectric states that may appear identical from macroscopic measurements, yet they are unique at the local level. The experimental results have been analyzed theoretically by a simple microscopic model of switching. According to the model simulations, each analog state can be associated with a domain structure that captures subtle variations of the previously applied electric field as well as structural information about the inhomogeneities at the local level. The generation and control of such partially switched analog states may be important for new applications of ferroelectric materials to multi-value memories or in the field of artificial intelligence.

  13. Conscious Augmentation of Creative State Enhances "Real" Creativity in Open-Ended Analogical Reasoning.

    Science.gov (United States)

    Weinberger, Adam B; Iyer, Hari; Green, Adam E

    2016-01-01

    Humans have an impressive ability to augment their creative state (i.e., to consciously try and succeed at thinking more creatively). Though this "thinking cap" phenomenon is commonly experienced, the range of its potential has not been fully explored by creativity research, which has often focused instead on creativity as a trait. A key question concerns the extent to which conscious augmentation of state creativity can improve creative reasoning. Although artistic creativity is also of great interest, it is creative reasoning that frequently leads to innovative advances in science and industry. Here, we studied state creativity in analogical reasoning, a form of relational reasoning that spans the conceptual divide between intelligence and creativity and is a core mechanism for creative innovation. Participants performed a novel Analogy Finding Task paradigm in which they sought valid analogical connections in a matrix of word-pairs. An explicit creativity cue elicited formation of substantially more creative analogical connections (measured via latent semantic analysis). Critically, the increase in creative analogy formation was not due to a generally more liberal criterion for analogy formation (that is, it appeared to reflect "real" creativity rather than divergence at the expense of appropriateness). The use of an online sample provided evidence that state creativity augmentation can be successfully elicited by remote cuing in an online environment. Analysis of an intelligence measure provided preliminary indication that the influential "threshold hypothesis," which has been proposed to characterize the relationship between intelligence and trait creativity, may be extensible to the new domain of state creativity.

  14. Uses of solid state analogies in elementary particle theory

    International Nuclear Information System (INIS)

    Anderson, P.W.

    1976-01-01

    The solid state background of some of the modern ideas of field theory is reviewed, and additional examples of model situations in solid state or many-body theory which may have relevance to fundamental theories of elementary particles are adduced

  15. Comparative effects of curcumin and an analog of curcumin on alcohol and PUFA induced oxidative stress.

    Science.gov (United States)

    Rukkumani, Rajagopalan; Aruna, Kode; Varma, Penumathsa Suresh; Rajasekaran, Kallikat Narayanan; Menon, Venugopal Padmanabhan

    2004-08-20

    Alcoholic liver disease is a major medical complication of alcohol abuse and a common liver disease in western countries. Increasing evidence demonstrates that oxidative stress plays an important etiologic role in the development of alcoholic liver disease. Alcohol alone or in combination with high fat is known to cause oxidative injury. The present study therefore aims at evaluating the protective role of curcumin, an active principle of turmeric and a synthetic analog of curcumin (CA) on alcohol and thermally oxidised sunflower oil (DeltaPUFA) induced oxidative stress. Male albino Wistar rats were used for the experimental study. The liver marker enzymes: gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), the lipid peroxidative indices: thiobarbituric acid reactive substances (TBARS) and hydroperoxides (HP) and antioxidants such as vitamin C, vitamin E, reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) were used as biomarkers for testing the antioxidant potential of the drugs. The liver marker enzymes and lipid peroxidative indices were increased significantly in alcohol, DeltaPUFA and alcohol + DeltaPUFA groups. Administration of curcumin and CA abrograted this effect. The antioxidant status which was decreased in alcohol, DeltaPUFA and alcohol + DeltaPUFA groups was effectively modulated by both curcumin and CA treatment. However, the reduction in oxidative stress was more pronounced in CA treatment groups compared to curcumin. In conclusion, these observations show that CA exerts its protective effect by decreasing the lipid peroxidation and improving antioxidant status, thus proving itself as an effective antioxidant.

  16. Using Rubber-Elastic Material-Ideal Gas Analogies To Teach Introductory Thermodynamics. Part I: Equations of State.

    Science.gov (United States)

    Smith, Brent

    2002-01-01

    Describes equations of state as a supplement to an introductory thermodynamics undergraduate course. Uses rubber-elastic materials (REM) which have strong analogies to the concept of an ideal gas and explains the molar basis of REM. Provides examples of the analogies between ideal gas and REM and mathematical analogies. (Contains 22 references.)…

  17. Conscious Augmentation of Creative State Enhances "Real" Creativity in Open-Ended Analogical Reasoning.

    Directory of Open Access Journals (Sweden)

    Adam B Weinberger

    Full Text Available Humans have an impressive ability to augment their creative state (i.e., to consciously try and succeed at thinking more creatively. Though this "thinking cap" phenomenon is commonly experienced, the range of its potential has not been fully explored by creativity research, which has often focused instead on creativity as a trait. A key question concerns the extent to which conscious augmentation of state creativity can improve creative reasoning. Although artistic creativity is also of great interest, it is creative reasoning that frequently leads to innovative advances in science and industry. Here, we studied state creativity in analogical reasoning, a form of relational reasoning that spans the conceptual divide between intelligence and creativity and is a core mechanism for creative innovation. Participants performed a novel Analogy Finding Task paradigm in which they sought valid analogical connections in a matrix of word-pairs. An explicit creativity cue elicited formation of substantially more creative analogical connections (measured via latent semantic analysis. Critically, the increase in creative analogy formation was not due to a generally more liberal criterion for analogy formation (that is, it appeared to reflect "real" creativity rather than divergence at the expense of appropriateness. The use of an online sample provided evidence that state creativity augmentation can be successfully elicited by remote cuing in an online environment. Analysis of an intelligence measure provided preliminary indication that the influential "threshold hypothesis," which has been proposed to characterize the relationship between intelligence and trait creativity, may be extensible to the new domain of state creativity.

  18. Conscious Augmentation of Creative State Enhances “Real” Creativity in Open-Ended Analogical Reasoning

    Science.gov (United States)

    Weinberger, Adam B.; Iyer, Hari; Green, Adam E.

    2016-01-01

    Humans have an impressive ability to augment their creative state (i.e., to consciously try and succeed at thinking more creatively). Though this “thinking cap” phenomenon is commonly experienced, the range of its potential has not been fully explored by creativity research, which has often focused instead on creativity as a trait. A key question concerns the extent to which conscious augmentation of state creativity can improve creative reasoning. Although artistic creativity is also of great interest, it is creative reasoning that frequently leads to innovative advances in science and industry. Here, we studied state creativity in analogical reasoning, a form of relational reasoning that spans the conceptual divide between intelligence and creativity and is a core mechanism for creative innovation. Participants performed a novel Analogy Finding Task paradigm in which they sought valid analogical connections in a matrix of word-pairs. An explicit creativity cue elicited formation of substantially more creative analogical connections (measured via latent semantic analysis). Critically, the increase in creative analogy formation was not due to a generally more liberal criterion for analogy formation (that is, it appeared to reflect “real” creativity rather than divergence at the expense of appropriateness). The use of an online sample provided evidence that state creativity augmentation can be successfully elicited by remote cuing in an online environment. Analysis of an intelligence measure provided preliminary indication that the influential “threshold hypothesis,” which has been proposed to characterize the relationship between intelligence and trait creativity, may be extensible to the new domain of state creativity. PMID:26959821

  19. Deaths Involving Fentanyl, Fentanyl Analogs, and U-47700 - 10 States, July-December 2016.

    Science.gov (United States)

    O'Donnell, Julie K; Halpin, John; Mattson, Christine L; Goldberger, Bruce A; Gladden, R Matthew

    2017-11-03

    Preliminary estimates of U.S. drug overdose deaths exceeded 60,000 in 2016 and were partially driven by a fivefold increase in overdose deaths involving synthetic opioids (excluding methadone), from 3,105 in 2013 to approximately 20,000 in 2016 (1,2). Illicitly manufactured fentanyl, a synthetic opioid 50-100 times more potent than morphine, is primarily responsible for this rapid increase (3,4). In addition, fentanyl analogs such as acetylfentanyl, furanylfentanyl, and carfentanil are being detected increasingly in overdose deaths (5,6) and the illicit opioid drug supply (7). Carfentanil is estimated to be 10,000 times more potent than morphine (8). Estimates of the potency of acetylfentanyl and furanylfentanyl vary but suggest that they are less potent than fentanyl (9). Estimates of relative potency have some uncertainty because illicit fentanyl analog potency has not been evaluated in humans. This report describes opioid overdose deaths during July-December 2016 that tested positive for fentanyl, fentanyl analogs, or U-47700, an illicit synthetic opioid, in 10 states participating in CDC's Enhanced State Opioid Overdose Surveillance (ESOOS) program.* Fentanyl analogs are similar in chemical structure to fentanyl but not routinely detected because specialized toxicology testing is required. Fentanyl was detected in at least half of opioid overdose deaths in seven of 10 states, and 57% of fentanyl-involved deaths also tested positive for other illicit drugs, such as heroin. Fentanyl analogs were present in >10% of opioid overdose deaths in four states, with carfentanil, furanylfentanyl, and acetylfentanyl identified most frequently. Expanded surveillance for opioid overdoses, including testing for fentanyl and fentanyl analogs, assists in tracking the rapidly changing illicit opioid market and informing innovative interventions designed to reduce opioid overdose deaths.

  20. The two dynamical states in sinusoidal potentials: An analog simulation experiment

    Science.gov (United States)

    Sawkmie, Ivan Skhem; Mahato, Mangal C.

    2018-04-01

    The phenomenon of stochastic resonance (SR) is usually found to occur theoretically as well as experimentally in bi-stable systems [1]. Recently, it was numerically shown that SR is found to occur in underdamped (friction coefficient γ) sinusoidal potentials also. The occurrence of SR is explained in terms of two competing dynamical states of trajectories as a response to the external periodic drive. We setup an analog simulation experiment similar to the analog simulation work done earlier to study stochastic nonlinear dynamics [2], to verify the existence of the two dynamical states and to investigate the occurrence of SR in sinusoidal potentials obtained earlier [3]. We discuss our experimental setup and the results obtained in detail.

  1. Charge independence and charge symmetry breaking interactions and the Coulomb energy anomaly in isobaric analog states

    International Nuclear Information System (INIS)

    Suzuki, Toshio; Sagawa, H.; Giai, N. van.

    1992-01-01

    Effects of CIB (charge independence breaking) and CSB (charge symmetry breaking) interactions on the Coulomb displacement energies of isobaric analog states are investigated for 48 Ca, 90 Zr and 208 Pb. Mass number dependence of the Coulomb energy anomalies is well explained when CIB and CSB interactions are used which reproduce the differences of the scattering lengths as well as those of the effective ranges of low energy nucleon-nucleon scattering. (author) 17 refs., 3 figs., 3 tabs

  2. Analog Amplitude Modulation of a High Voltage, Solid State Inductive Adder, Pulse Generator Using MOSFETS

    International Nuclear Information System (INIS)

    Gower, E J; Sullivan, J S

    2002-01-01

    High voltage, solid state, inductive adder, pulse generators have found increasing application as fast kicker pulse modulators for charged particle beams. The solid state, inductive adder, pulse generator is similar in operation to the linear induction accelerator. The main difference is that the solid state, adder couples energy by transformer action from multiple primaries to a voltage summing stalk, instead of an electron beam. Ideally, the inductive adder produces a rectangular voltage pulse at the load. In reality, there is usually some voltage variation at the load due to droop on primary circuit storage capacitors, or, temporal variations in the load impedance. Power MOSFET circuits have been developed to provide analog modulation of the output voltage amplitude of a solid state, inductive adder, pulse generator. The modulation is achieved by including MOSFET based, variable subtraction circuits in the multiple primary stack. The subtraction circuits can be used to compensate for voltage droop, or, to tailor the output pulse amplitude to provide a desired effect in the load. Power MOSFET subtraction circuits have been developed to modulate short, temporal (60-400 ns), voltage and current pulses. MOSFET devices have been tested up to 20 amps and 800 Volts with a band pass of 50 MHz. An analog modulation cell has been tested in a five cell high, voltage adder stack

  3. Success and failure of the plasma analogy for Laughlin states on a torus

    Science.gov (United States)

    Fremling, Mikael

    2017-01-01

    We investigate the nature of the plasma analogy for the Laughlin wave function on a torus describing the quantum Hall plateau at ν =\\frac{1}{q} . We first establish, as expected, that the plasma is screening if there are no short nontrivial paths around the torus. We also find that when one of the handles has a short circumference—i.e. the thin-torus limit—the plasma no longer screens. To quantify this we compute the normalization of the Laughlin state, both numerically and analytically. In the thin torus limit, the analytical form of the normalization simplify and we can reconstruct the normalization and analytically extend it back into the 2D regime. We find that there are geometry dependent corrections to the normalization, and this in turn implies that the plasma in the plasma analogy is not screening when in the thin torus limit. Despite the breaking of the plasma analogy in this limit, the analytical approximation is still a good description of the normalization for all tori, and also allows us to compute hall viscosity at intermediate thickness.

  4. Oxidation-state maxima in plutonium chemistry

    International Nuclear Information System (INIS)

    Silver, G.L.

    2013-01-01

    Maxima in the fractions of the trivalent and hexavalent oxidation states of plutonium are inherent in the algebra of its disproportionation reactions. The maxima do not support overall disproportionation equations as satisfactory representations of aqueous plutonium. (author)

  5. The Use of a Solid State Analog Television Transmitter as a Superconducting Electron Gun Power Amplifier

    Energy Technology Data Exchange (ETDEWEB)

    J.G. Kulpin, K.J. Kleman, R.A. Legg

    2012-07-01

    A solid state analog television transmitter designed for 200 MHz operation is being commissioned as a radio frequency power amplifier on the Wisconsin superconducting electron gun cavity. The amplifier consists of three separate radio frequency power combiner cabinets and one monitor and control cabinet. The transmitter employs rugged field effect transistors built into one kilowatt drawers that are individually hot swappable at maximum continuous power output. The total combined power of the transmitter system is 33 kW at 200 MHz, output through a standard coaxial transmission line. A low level radio frequency system is employed to digitally synthesize the 200 MHz signal and precisely control amplitude and phase.

  6. Dependence of isobar-analog state properties on variable part of Coulomb potential

    International Nuclear Information System (INIS)

    Dzhafarov, I.G.; Kuliev, A.A.; Salamov, D.I.

    1986-01-01

    Within the framework of the self-consistent approach and with the method of strength functions the fragmentation of isobar-analog state (IAS) properties for all isobarie 0 + -states is investigated. Microscopic values of IAS energy, matrix elements of allowed and forbidden Fermi transitions as well as isospin impurity values in ground states of parent nuclei are obtained. Numerical calculations carried out for 42 Ca 42 Sc, 48 Ca 48 Sc, 64 Zn 64 Ga, 66 Zn 66 Ga, 90 Zr 90 Nb, 208 Pb 208 Bi isobaric nuclei with Woods-Saxon potential, are compared with predictions of different approches and experiment. The developed model by the authors permits to describe sufficiently well the experimental data

  7. Search for isobar-analog states of superheavy hydrogen isotopes5-7He

    Science.gov (United States)

    Chernyshev, B. A.; Gurov, Yu B.; Korotkova, L. Yu; Kuznetsov, D. S.; Lapushkin, S. V.; Tel'kushev, M. V.; Schurenkova, T. D.

    2016-02-01

    Search for isobar-analog states (IAS) of superheavy hydrogen isotopes 5-7H was performed among the high-excited states of helium isotopes 5-7He. The excited spectra were measured in stopped pion absorption by light nuclei. The experiment was performed at low energy pion channel of LANL with two-arm multilayer semiconductor spectrometer. Excited states of 5-7He were observed in three-body reaction channels on 10,11B nuclei. Several excited levels were observed for the first time. 6He excited state with Ex = 27.0(8) MeV observed in 10B(π-,pt)X channel is an IAS candidate for 6H with Er ∼ 5.5 MeV. 7He excited state with Ex = 24.8(4) MeV observed in 10B(π-,pd)X, nB(π-,pt)X and nB(π-,dd)X channels is an IAS candidate for 7H with Er ∼ 3 MeV.

  8. Compliance-Free, Digital SET and Analog RESET Synaptic Characteristics of Sub-Tantalum Oxide Based Neuromorphic Device.

    Science.gov (United States)

    Abbas, Yawar; Jeon, Yu-Rim; Sokolov, Andrey Sergeevich; Kim, Sohyeon; Ku, Boncheol; Choi, Changhwan

    2018-01-19

    A two terminal semiconducting device like a memristor is indispensable to emulate the function of synapse in the working memory. The analog switching characteristics of memristor play a vital role in the emulation of biological synapses. The application of consecutive voltage sweeps or pulses (action potentials) changes the conductivity of the memristor which is considered as the fundamental cause of the synaptic plasticity. In this study, a neuromorphic device using an in-situ growth of sub-tantalum oxide switching layer is fabricated, which exhibits the digital SET and analog RESET switching with an electroforming process without any compliance current (compliance free). The process of electroforming and SET is observed at the positive sweeps of +2.4 V and +0.86 V, respectively, while multilevel RESET is observed with the consecutive negative sweeps in the range of 0 V to -1.2 V. The movement of oxygen vacancies and gradual change in the anatomy of the filament is attributed to digital SET and analog RESET switching characteristics. For the Ti/Ta 2 O 3-x /Pt neuromorphic device, the Ti top and Pt bottom electrodes are considered as counterparts of the pre-synaptic input terminal and a post-synaptic output terminal, respectively.

  9. Silibinin attenuates sulfur mustard analog-induced skin injury by targeting multiple pathways connecting oxidative stress and inflammation.

    Directory of Open Access Journals (Sweden)

    Neera Tewari-Singh

    Full Text Available Chemical warfare agent sulfur mustard (HD inflicts delayed blistering and incapacitating skin injuries. To identify effective countermeasures against HD-induced skin injuries, efficacy studies were carried out employing HD analog 2-chloroethyl ethyl sulfide (CEES-induced injury biomarkers in skin cells and SKH-1 hairless mouse skin. The data demonstrate strong therapeutic efficacy of silibinin, a natural flavanone, in attenuating CEES-induced skin injury and oxidative stress. In skin cells, silibinin (10 µM treatment 30 min after 0.35/0.5 mM CEES exposure caused a significant (p90%, and activation of transcription factors NF-κB and AP-1 (complete reversal. Similarly, silibinin treatment was also effective in attenuating CEES-induced oxidative stress measured by 4-hydroxynonenal and 5,5-dimethyl-2-(8-octanoic acid-1-pyrolline N-oxide protein adduct formation, and 8-oxo-2-deoxyguanosine levels. Since our previous studies implicated oxidative stress, in part, in CEES-induced toxic responses, the reversal of CEES-induced oxidative stress and other toxic effects by silibinin in this study indicate its pleiotropic therapeutic efficacy. Together, these findings support further optimization of silibinin in HD skin toxicity model to develop a novel effective therapy for skin injuries by vesicants.

  10. Thermodynamic Ground States of Complex Oxide Heterointerfaces

    DEFF Research Database (Denmark)

    Gunkel, F.; Hoffmann-Eifert, S.; Heinen, R. A.

    2017-01-01

    The formation mechanism of 2-dimensional electron gases (2DEGs) at heterointerfaces between nominally insulating oxides is addressed with a thermodynamical approach. We provide a comprehensive analysis of the thermodynamic ground states of various 2DEG systems directly probed in high temperature...

  11. Higher Americium Oxidation State Research Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    Mincher, Bruce J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Law, Jack D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Goff, George S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moyer, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Burns, Jon D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lumetta, Gregg J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sinkov, Sergey I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shehee, Thomas C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hobbs, David T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-12-18

    The partitioning of hexavalent Am from dissolved nuclear fuel requires the ability to efficiently oxidize Am(III) to Am(VI) and to maintain that oxidation state for a length of time sufficient to perform the separation. Several oxidants have been, or are being developed. Chemical oxidants include Ag-catalyzed ozone, Ag-catalyzed peroxydisulfate, Cu(III) periodate, and sodium bismuthate. Hexavalent americium has also now successfully been prepared by electrolysis, using functionalized electrodes. So-called auto-reduction rates of Am(VI) are sufficiently slow to allow for separations. However, for separations based on solvent extraction or ion exchange using organic resins, the high valence state must be maintained under the reducing conditions of the organic phase contact, and a holding oxidant is probably necessary. Until now, only Cu(III) periodate and sodium bismuthate oxidation have been successfully combined with solvent extraction separations. Bismuthate oxidation provided the higher DAm, since it acts as its own holding oxidant, and a successful hot test using centrifugal contactors was performed. For the other oxidants, Ag-catalyzed peroxydisulfate will not oxidize americium in nitric acid concentrations above 0.3 M, and it is not being further investigated. Peroxydisulfate in the absence of Ag catalysis is being used to prepare Am(V) in ion exchange work, discussed below. Preliminary work with Ag-catalyzed ozone has been unsuccessful for extractions of Am(VI) from 6.5 M HNO3, and only one attempt at extraction, also from 6.5 M HNO3, using the electrolytic oxidation has been attempted. However, this high acid concentration was based on the highest Am extraction efficiency using the bismuthate oxidant; which is only sparingly soluble, and thus the oxidation yield is based on bismuthate solubility. Lower acid concentrations may be sufficient with alternative oxidants and work with Ag-ozone, Cu(III) and electrolysis is on-going. Two non

  12. Decay mechanism of the fsub(7/2) isobaric analog state of 141Pr, (2)

    International Nuclear Information System (INIS)

    Uegaki, Junichi; Shoda, Katsufusa

    1975-01-01

    Experimental results on the f7/2 IAR(isobaric analog resonance) by 141 Pr (e, e'p) reaction were reported previously. This paper presents the results of further measurement on this reaction. The energy spectra of protons emitted by the 141 Pr (e, e'p) reaction, obtained at the electron energy Ee of 16.3, 15.5, 14.8 and 14.1 MeV, are shown. A peak seen at the proton energy Ep of 9.5 MeV in the spectrum taken at Ee=16.3 MeV shows the proton group decaying from the f7/2 isobaric analog state (IAS) to 140 Ce ground state, and the excitation energy of the f7/2 IAS was calculated as Ex=14.8 MeV. The cross-section of the reaction 141 Pr (γ, p 0 ) can be estimated from the spectra obtained, and was compared with that estimated from the 140 Ce (p, γ 0 ) reaction. The cross-section of the 141 Pr (e, e'p) reaction is shown as a function of incident electron energy, and the resonance intensity of the f7/2 IAR was estimated as (2.7 +- 1.3) x 10 -28 cm 2 MeV. The radiation width of the f7/2 IAR of 141 Pr was 25.8 eV, and this value is not in agreement with that obtained from 141 Pr (p, γ 0 ). The proton spectra of 141 Pr (γ, p) reaction can be obtained from the proton spectra of 141 Pr (e, e'p) reaction by assuming virtual photon spectra. The result was compared with the result of 140 Ce (p, p') reaction. The one particle-one hole state of neutrons distributed over the energy range between 5.3 and 6.3 MeV, and the first excited 2 + state was seen at Esub(p)=7.9 MeV. In the range between 6.3 and 7.8 MeV, a proton group existed, which did not agree with the data of proton scattering. More precise study is under consideration. (Kato, T.)

  13. Development of analog solid-state photo-detectors for Positron Emission Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Bisogni, Maria Giuseppina, E-mail: giuseppina.bisogni@pi.infn.it; Morrocchi, Matteo

    2016-02-11

    Solid-state photo-detectors are one of the main innovations of past century in the field of sensors. First produced in the early forties with the invention of the p–n junction in silicon and the study of its optical properties, photo-detectors received a major boost in the sixties when the p-i-n (PIN) photodiode was developed and successfully used in several applications. The development of devices with internal gain, avalanche photodiodes (APD) first and then Geiger-mode avalanche photodiodes, named single photon avalanche diode (SPAD), leads to a substantial improvement in sensitivity and allowed single photon detection. Later on, thousands of SPADs have been assembled in arrays of few millimeters squared (named SiPM, silicon photo-multiplier) with single photon resolution. The high internal gain of SiPMs, together with other features peculiar of the silicon technology like compactness, speed and compatibility with magnetic fields, promoted SiPMs as the principal photo-detector competitor of photomultipliers in many applications from radiation detection to medical imaging. This paper provides a review of the properties of analog solid-state photo-detectors. Particular emphasis is given to latest advances on Positron Emission Tomography instrumentation boosted by the adoption of the silicon photo-detectors as an alternative to photomultiplier tubes (PMTs). Special attention is dedicated to the SiPMs, which are playing a key role in the development of innovative scanners.

  14. Development of analog solid-state photo-detectors for Positron Emission Tomography

    International Nuclear Information System (INIS)

    Bisogni, Maria Giuseppina; Morrocchi, Matteo

    2016-01-01

    Solid-state photo-detectors are one of the main innovations of past century in the field of sensors. First produced in the early forties with the invention of the p–n junction in silicon and the study of its optical properties, photo-detectors received a major boost in the sixties when the p-i-n (PIN) photodiode was developed and successfully used in several applications. The development of devices with internal gain, avalanche photodiodes (APD) first and then Geiger-mode avalanche photodiodes, named single photon avalanche diode (SPAD), leads to a substantial improvement in sensitivity and allowed single photon detection. Later on, thousands of SPADs have been assembled in arrays of few millimeters squared (named SiPM, silicon photo-multiplier) with single photon resolution. The high internal gain of SiPMs, together with other features peculiar of the silicon technology like compactness, speed and compatibility with magnetic fields, promoted SiPMs as the principal photo-detector competitor of photomultipliers in many applications from radiation detection to medical imaging. This paper provides a review of the properties of analog solid-state photo-detectors. Particular emphasis is given to latest advances on Positron Emission Tomography instrumentation boosted by the adoption of the silicon photo-detectors as an alternative to photomultiplier tubes (PMTs). Special attention is dedicated to the SiPMs, which are playing a key role in the development of innovative scanners.

  15. Inhibition of inducible Nitric Oxide Synthase by a mustard gas analog in murine macrophages

    Directory of Open Access Journals (Sweden)

    Smith Milton

    2006-11-01

    Full Text Available Abstract Background 2-Chloroethyl ethyl sulphide (CEES is a sulphur vesicating agent and an analogue of the chemical warfare agent 2,2'-dichlorodiethyl sulphide, or sulphur mustard gas (HD. Both CEES and HD are alkylating agents that influence cellular thiols and are highly toxic. In a previous publication, we reported that lipopolysaccharide (LPS enhances the cytotoxicity of CEES in murine RAW264.7 macrophages. In the present investigation, we studied the influence of CEES on nitric oxide (NO production in LPS stimulated RAW264.7 cells since NO signalling affects inflammation, cell death, and wound healing. Murine macrophages stimulated with LPS produce NO almost exclusively via inducible nitric oxide synthase (iNOS activity. We suggest that the influence of CEES or HD on the cellular production of NO could play an important role in the pathophysiological responses of tissues to these toxicants. In particular, it is known that macrophage generated NO synthesised by iNOS plays a critical role in wound healing. Results We initially confirmed that in LPS stimulated RAW264.7 macrophages NO is exclusively generated by the iNOS form of nitric oxide synthase. CEES treatment inhibited the synthesis of NO (after 24 hours in viable LPS-stimulated RAW264.7 macrophages as measured by either nitrite secretion into the culture medium or the intracellular conversion of 4,5-diaminofluorescein diacetate (DAF-2DA or dichlorofluorescin diacetate (DCFH-DA. Western blots showed that CEES transiently decreased the expression of iNOS protein; however, treatment of active iNOS with CEES in vitro did not inhibit its enzymatic activity Conclusion CEES inhibits NO production in LPS stimulated macrophages by decreasing iNOS protein expression. Decreased iNOS expression is likely the result of CEES induced alteration in the nuclear factor kappa B (NF-κB signalling pathway. Since NO can act as an antioxidant, the CEES induced down-regulation of iNOS in LPS

  16. Photochemical oxidants: state of the science.

    Science.gov (United States)

    Kley, D; Kleinmann, M; Sanderman, H; Krupa, S

    1999-01-01

    Atmospheric photochemical processes resulting in the production of tropospheric ozone (O(3)) and other oxidants are described. The spatial and temporal variabilities in the occurrence of surface level oxidants and their relationships to air pollution meteorology are discussed. Models of photooxidant formation are reviewed in the context of control strategies and comparisons are provided of the air concentrations of O(3) at select geographic locations around the world. This overall oxidant (O(3)) climatology is coupled to human health and ecological effects. The discussion of the effects includes both acute and chronic responses, mechanisms of action, human epidemiological and plant population studies and briefly, efforts to establish cause-effect relationships through numerical modeling. A short synopsis is provided of the interactive effects of O(3) with other abiotic and biotic factors. The overall emphasis of the paper is on identifying the current uncertainties and gaps in our understanding of the state of the science and some suggestions as to how they may be addressed.

  17. Plutonium disproportionation. Hydrolysis and local oxidation-state maxima

    International Nuclear Information System (INIS)

    Silver, G.L.

    2014-01-01

    Local maxima in the fractions of the trivalent and hexavalent oxidation states are inherent in the algebra of Pu disproportionation reactions. A new method predicts the pH and the oxidation-state fractions at maximum. Tabulated results illustrate the effects of the Pu oxidation number and Pu(IV) hydrolysis on the maxima. This method suggests a new laboratory approach for discovering Pu oxidation-state maxima. (author)

  18. Erythropoietin and a nonerythropoietic peptide analog promote aortic endothelial cell repair under hypoxic conditions: role of nitric oxide

    Directory of Open Access Journals (Sweden)

    Heikal L

    2016-08-01

    Full Text Available Lamia Heikal,1 Pietro Ghezzi,1 Manuela Mengozzi,1 Blanka Stelmaszczuk,2 Martin Feelisch,2 Gordon AA Ferns1 1Brighton and Sussex Medical School, Falmer, Brighton, 2Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton General Hospital and Institute for Life Sciences, Southampton, UK Abstract: The cytoprotective effects of erythropoietin (EPO and an EPO-related nonerythropoietic analog, pyroglutamate helix B surface peptide (pHBSP, were investigated in an in vitro model of bovine aortic endothelial cell injury under normoxic (21% O2 and hypoxic (1% O2 conditions. The potential molecular mechanisms of these effects were also explored. Using a model of endothelial injury (the scratch assay, we found that, under hypoxic conditions, EPO and pHBSP enhanced scratch closure by promoting cell migration and proliferation, but did not show any effect under normoxic conditions. Furthermore, EPO protected bovine aortic endothelial cells from staurosporine-induced apoptosis under hypoxic conditions. The priming effect of hypoxia was associated with stabilization of hypoxia inducible factor-1α, EPO receptor upregulation, and decreased Ser-1177 phosphorylation of endothelial nitric oxide synthase (NOS; the effect of hypoxia on the latter was rescued by EPO. Hypoxia was associated with a reduction in nitric oxide (NO production as assessed by its oxidation products, nitrite and nitrate, consistent with the oxygen requirement for endogenous production of NO by endothelial NOS. However, while EPO did not affect NO formation in normoxia, it markedly increased NO production, in a manner sensitive to NOS inhibition, under hypoxic conditions. These data are consistent with the notion that the tissue-protective actions of EPO-related cytokines in pathophysiological settings associated with poor oxygenation are mediated by NO. These findings may be particularly relevant to atherogenesis and postangioplasty restenosis. Keywords

  19. Structure-activity relationships of novel salicylaldehyde isonicotinoyl hydrazone (SIH analogs: iron chelation, anti-oxidant and cytotoxic properties.

    Directory of Open Access Journals (Sweden)

    Eliška Potůčková

    Full Text Available Salicylaldehyde isonicotinoyl hydrazone (SIH is a lipophilic, tridentate iron chelator with marked anti-oxidant and modest cytotoxic activity against neoplastic cells. However, it has poor stability in an aqueous environment due to the rapid hydrolysis of its hydrazone bond. In this study, we synthesized a series of new SIH analogs (based on previously described aromatic ketones with improved hydrolytic stability. Their structure-activity relationships were assessed with respect to their stability in plasma, iron chelation efficacy, redox effects and cytotoxic activity against MCF-7 breast adenocarcinoma cells. Furthermore, studies assessed the cytotoxicity of these chelators and their ability to afford protection against hydrogen peroxide-induced oxidative injury in H9c2 cardiomyoblasts. The ligands with a reduced hydrazone bond, or the presence of bulky alkyl substituents near the hydrazone bond, showed severely limited biological activity. The introduction of a bromine substituent increased ligand-induced cytotoxicity to both cancer cells and H9c2 cardiomyoblasts. A similar effect was observed when the phenolic ring was exchanged with pyridine (i.e., changing the ligating site from O, N, O to N, N, O, which led to pro-oxidative effects. In contrast, compounds with long, flexible alkyl chains adjacent to the hydrazone bond exhibited specific cytotoxic effects against MCF-7 breast adenocarcinoma cells and low toxicity against H9c2 cardiomyoblasts. Hence, this study highlights important structure-activity relationships and provides insight into the further development of aroylhydrazone iron chelators with more potent and selective anti-neoplastic effects.

  20. Search for the weak non-analog Fermi branch in the 42Sc ground state beta decay

    International Nuclear Information System (INIS)

    DelVecchio, R.M.; Daehnick, W.W.

    1978-01-01

    We have searched for the β-decay branch from the 4 2Sc ground state to the 1.837 MeV level in 4 2Ca. Since both states are J/sup π/ = 0 + , T = 1, this decay is an example of a non-analog Fermi decay which could occur by reason of some mixing of the analog ground states into the lowest excited 0 + state in both 4 2Sc and 4 2Ca. As a signal for this branch, we looked for a subsequent cascade γ ray with a Ge(Li) detector-rabbit arrangement. We found a branching ratio of (2.2 +- 1.7) x 10 - 5 relative to the superallowed ground state to ground state decay. Interpreted as an upper limit, this corresponds to a branching ratio - 5 at the 68% confidence level. This result is at the lower bound of what present theory can predict with a Coulomb force mixing calculation

  1. Optoelectronic link for analog signals from solid state detectors in high energy physics

    International Nuclear Information System (INIS)

    Manfredi, P.F.; Speziali, V.

    1983-01-01

    An optoelectric link has been made to transmit analog signals over a long distance between the beam area and the remote-end data acquisition instrumentation in high energy experiments. The optoelectronic link is intended for silicon target applications and it is designed to work on the signals at the output of a low noise amplifier system. Its advantages over a conventional galvanic connection as well as its limitations are discussed. (orig.)

  2. A theory for bioinorganic chemical reactivity of oxometal complexes and analogous oxidants: the exchange and orbital-selection rules.

    Science.gov (United States)

    Usharani, Dandamudi; Janardanan, Deepa; Li, Chunsen; Shaik, Sason

    2013-02-19

    Over the past decades metalloenzymes and their synthetic models have emerged as an area of increasing research interest. The metalloenzymes and their synthetic models oxidize organic molecules using oxometal complexes (OMCs), especially oxoiron(IV)-based ones. Theoretical studies have helped researchers to characterize the active species and to resolve mechanistic issues. This activity has generated massive amounts of data on the relationship between the reactivity of OMCs and the transition metal's identity, oxidation state, ligand sphere, and spin state. Theoretical studies have also produced information on transition state (TS) structures, reaction intermediates, barriers, and rate-equilibrium relationships. For example, the experimental-theoretical interplay has revealed that nonheme enzymes carry out H-abstraction from strong C-H bonds using high-spin (S = 2) oxoiron(IV) species with four unpaired electrons on the iron center. However, other reagents with higher spin states and more unpaired electrons on the metal are not as reactive. Still other reagents carry out these transformations using lower spin states with fewer unpaired electrons on the metal. The TS structures for these reactions exhibit structural selectivity depending on the reactive spin states. The barriers and thermodynamic driving forces of the reactions also depend on the spin state. H-Abstraction is preferred over the thermodynamically more favorable concerted insertion into C-H bonds. Currently, there is no unified theoretical framework that explains the totality of these fascinating trends. This Account aims to unify this rich chemistry and understand the role of unpaired electrons on chemical reactivity. We show that during an oxidative step the d-orbital block of the transition metal is enriched by one electron through proton-coupled electron transfer (PCET). That single electron elicits variable exchange interactions on the metal, which in turn depend critically on the number of

  3. Carbon monoxide oxidation over three different states of copper: Development of a model metal oxide catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Jernigan, Glenn Geoffrey [California Univ., Berkeley, CA (United States). Dept. of Chemistry

    1994-10-01

    Carbon monoxide oxidation was performed over the three different oxidation states of copper -- metallic (Cu), copper (I) oxide (Cu2O), and copper (II) oxide (CuO) as a test case for developing a model metal oxide catalyst amenable to study by the methods of modern surface science and catalysis. Copper was deposited and oxidized on oxidized supports of aluminum, silicon, molybdenum, tantalum, stainless steel, and iron as well as on graphite. The catalytic activity was found to decrease with increasing oxidation state (Cu > Cu2O > CuO) and the activation energy increased with increasing oxidation state (Cu, 9 kcal/mol < Cu2O, 14 kcal/mol < CuO, 17 kcal/mol). Reaction mechanisms were determined for the different oxidation states. Lastly, NO reduction by CO was studied. A Cu and CuO catalyst were exposed to an equal mixture of CO and NO at 300--350 C to observe the production of N2 and CO2. At the end of each reaction, the catalyst was found to be Cu2O. There is a need to study the kinetics of this reaction over the different oxidation states of copper.

  4. Charge exchange (p,n) reactions to the isobaric analog states of high Z nuclei: 73< or =Z< or =92

    International Nuclear Information System (INIS)

    Hansen, L.F.; Grimes, S.M.; Poppe, C.H.; Wong, C.

    1983-01-01

    Differential cross sections have been measured for the (p,n) reaction to the isobaric analog states of 181 Ta, 197 Au, 209 Bi, 232 Th, and 238 U at an incident energy of 27 MeV. Because of the importance of collective effects in this mass region, coupled-channel calculations have been carried out in the analysis of the data. Optical potentials obtained from the Lane model for the charge exchange reaction have been used in the simultaneous analysis of coupled proton and neutron channels. The sensitivity of the calculations to the different couplings between the levels and to the magnitude of the isovector potentials, V 1 and W 1 , is discussed. The good agreement obtained between the measured and calculated (p,n) angular distributions to the analog state confirms the validity of the Lane formalism for high-Z nuclei (Z> or =50). Elastic neutron differential cross sections inferred from the coupled-channel analysis are compared with measurements available in the literature in the energy range 7--8 MeV. The results of these calculations agree with the measured values as well as the results of calculations made using global neutron optical potential parameters optimized to fit neutron data

  5. Analogies and surprising differences between recombinant nitric oxide synthase-like proteins from Staphylococcus aureus and Bacillus anthracis in their interactions with l-arginine analogs and iron ligands.

    Science.gov (United States)

    Salard, Isabelle; Mercey, Emilie; Rekka, Eleni; Boucher, Jean-Luc; Nioche, Pierre; Mikula, Ivan; Martasek, Pavel; Raman, C S; Mansuy, Daniel

    2006-12-01

    Genome sequencing has recently shown the presence of genes coding for NO-synthase (NOS)-like proteins in bacteria. The roles of these proteins remain unclear. The interactions of a series of l-arginine (l-arg) analogs and iron ligands with two recombinant NOS-like proteins from Staphylococcus aureus (saNOS) and Bacillus anthracis (baNOS) have been studied by UV-visible spectroscopy. SaNOS and baNOS in their ferric native state, as well as their complexes with l-arg analogs and with various ligands, exhibit spectral characteristics highly similar to the corresponding complexes of heme-thiolate proteins such as cytochromes P450 and NOSs. However, saNOS greatly differs from baNOS at the level of three main properties: (i) native saNOS mainly exists under an hexacoordinated low-spin ferric state whereas native baNOS is mainly high-spin, (ii) the addition of tetrahydrobiopterin (H4B) or H4B analogs leads to an increase of the affinity of l-arg for saNOS but not for baNOS, and (iii) saNOS Fe(II), contrary to baNOS, binds relatively bulky ligands such as nitrosoalkanes and tert-butylisocyanide. Thus, saNOS exhibits properties very similar to those of the oxygenase domain of inducible NOS (iNOS(oxy)) not containing H4B, as expected for a NOSoxy-like protein that does not contain H4B. By contrast, the properties of baNOS which look like those of H4B-containing iNOS(oxy) are unexpected for a NOS-like protein not containing H4B. The origin of these surprising properties of baNOS remains to be determined.

  6. Processing deficits in monitoring analog and digital displays: Implications for attentional theory and mental-state estimation research

    Science.gov (United States)

    Payne, David G.; Gunther, Virginia A. L.

    1988-01-01

    Subjects performed short term memory tasks, involving both spatial and verbal components, and a visual monitoring task involving either analog or digital display formats. These two tasks (memory vs. monitoring) were performed both singly and in conjunction. Contrary to expectations derived from multiple resource theories of attentional processes, there was no evidence that when the two tasks involved the same cognitive codes (i.e., either both spatial or both verbal/linguistics) there was more of a dual task performance decrement than when the two tasks employed different cognitive codes/processes. These results are discussed in terms of their implications for theories of attentional processes and also for research in mental state estimation.

  7. Combined crystallographic and spectroscopic analysis of Trematomus bernacchii hemoglobin highlights analogies and differences in the peculiar oxidation pathway of Antarctic fish hemoglobins.

    Science.gov (United States)

    Merlino, Antonello; Vitagliano, Luigi; Howes, Barry D; Verde, Cinzia; di Prisco, Guido; Smulevich, Giulietta; Sica, Filomena; Vergara, Alessandro

    2009-12-01

    Recent studies have demonstrated that hemoglobins isolated from Antarctic fish undergo peculiar oxidation processes. Here we show, by combining crystallographic and spectroscopic data, that the oxidation pathway of Trematomus bernacchii hemoglobin (HbTb) is distinct from that observed for the major component of Trematomus newnesi (Hb1Tn), despite the high sequence identity of the two proteins and structural similarity of their ferrous and fully oxidized states. Resonance Raman analysis of HbTb autoxidation upon air-exposure reveals the absence of the oxidized pentacoordinated state that was observed for Hb1Tn. The HbTb oxidation pathway is characterized by two ferric species: an aquo hexacoordinated high spin state and a bis-histidyl hexacoordinated low spin form, which appear in the early stages of the oxidation process. The high resolution structure of an intermediate along the oxidation pathway has been determined at 1.4 A resolution. The analysis of the electron density of the heme pocket shows, for both the alpha and the beta iron, the coexistence of multiple binding states. In this partially oxidized form, HbTb exhibits significant deviations from the canonical R state both at the local and global level. The analysis of these modifications highlights the structural correlation between key functional regions of the protein.

  8. Analog computing

    CERN Document Server

    Ulmann, Bernd

    2013-01-01

    This book is a comprehensive introduction to analog computing. As most textbooks about this powerful computing paradigm date back to the 1960s and 1970s, it fills a void and forges a bridge from the early days of analog computing to future applications. The idea of analog computing is not new. In fact, this computing paradigm is nearly forgotten, although it offers a path to both high-speed and low-power computing, which are in even more demand now than they were back in the heyday of electronic analog computers.

  9. Thermal imagers: from ancient analog video output to state-of-the-art video streaming

    Science.gov (United States)

    Haan, Hubertus; Feuchter, Timo; Münzberg, Mario; Fritze, Jörg; Schlemmer, Harry

    2013-06-01

    The video output of thermal imagers stayed constant over almost two decades. When the famous Common Modules were employed a thermal image at first was presented to the observer in the eye piece only. In the early 1990s TV cameras were attached and the standard output was CCIR. In the civil camera market output standards changed to digital formats a decade ago with digital video streaming being nowadays state-of-the-art. The reasons why the output technique in the thermal world stayed unchanged over such a long time are: the very conservative view of the military community, long planning and turn-around times of programs and a slower growth of pixel number of TIs in comparison to consumer cameras. With megapixel detectors the CCIR output format is not sufficient any longer. The paper discusses the state-of-the-art compression and streaming solutions for TIs.

  10. Thinking Cap Plus Thinking Zap: tDCS of Frontopolar Cortex Improves Creative Analogical Reasoning and Facilitates Conscious Augmentation of State Creativity in Verb Generation.

    Science.gov (United States)

    Green, Adam E; Spiegel, Katherine A; Giangrande, Evan J; Weinberger, Adam B; Gallagher, Natalie M; Turkeltaub, Peter E

    2017-04-01

    Recent neuroimaging evidence indicates neural mechanisms that support transient improvements in creative performance (augmented state creativity) in response to cognitive interventions (creativity cueing). Separately, neural interventions via tDCS show encouraging potential for modulating neuronal function during creative performance. If cognitive and neural interventions are separately effective, can they be combined? Does state creativity augmentation represent "real" creativity, or do interventions simply yield divergence by diminishing meaningfulness/appropriateness? Can augmenting state creativity bolster creative reasoning that supports innovation, particularly analogical reasoning? To address these questions, we combined tDCS with creativity cueing. Testing a regionally specific hypothesis from neuroimaging, high-definition tDCS-targeted frontopolar cortex activity recently shown to predict state creativity augmentation. In a novel analogy finding task, participants under tDCS formulated substantially more creative analogical connections in a large matrix search space (creativity indexed via latent semantic analysis). Critically, increased analogical creativity was not due to diminished accuracy in discerning valid analogies, indicating "real" creativity rather than inappropriate divergence. A simpler relational creativity paradigm (modified verb generation) revealed a tDCS-by-cue interaction; tDCS further enhanced creativity cue-related increases in semantic distance. Findings point to the potential of noninvasive neuromodulation to enhance creative relational cognition, including augmentation of the deliberate effort to formulate connections between distant concepts. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  11. Non-equilibrium oxidation states of zirconium during early stages of metal oxidation

    International Nuclear Information System (INIS)

    Ma, Wen; Yildiz, Bilge; Herbert, F. William; Senanayake, Sanjaya D.

    2015-01-01

    The chemical state of Zr during the initial, self-limiting stage of oxidation on single crystal zirconium (0001), with oxide thickness on the order of 1 nm, was probed by synchrotron x-ray photoelectron spectroscopy. Quantitative analysis of the Zr 3d spectrum by the spectrum reconstruction method demonstrated the formation of Zr 1+ , Zr 2+ , and Zr 3+ as non-equilibrium oxidation states, in addition to Zr 4+ in the stoichiometric ZrO 2 . This finding resolves the long-debated question of whether it is possible to form any valence states between Zr 0 and Zr 4+ at the metal-oxide interface. The presence of local strong electric fields and the minimization of interfacial energy are assessed and demonstrated as mechanisms that can drive the formation of these non-equilibrium valence states of Zr

  12. Remarks on the occasion of the 25. anniversary of the discovery of isobaric-analog states

    International Nuclear Information System (INIS)

    Goodman, C.D.

    1987-01-01

    Roughly 25 years ago, John Anderson, the late Calvin Wong, John McClure, and Stewart Bloom made an interesting discovery. John and his colleagues had set out to measure the systematics of nuclear temperatures. They were to look at the spectra of evaporated neutrons from compound nuclei created by proton bombardment of various targets. The evaporation spectra should be smooth functions of energy. The smooth functions were there, but there was a sharp peak superimposed. No known physical phenomenon could produce the sharp peak, so it had to be an artifact of the electronics. However, John and his colleagues convinced themselves that the time-to-pulse-height converters were working right. Well then, it had to be a contaminant in the target. Sharp peaks had been seen for isospin mirror transitions, but this target, 23 51 V 28 , had five excess neutrons, so there could not be a mirror transition. The prevailing dogma was that isotopic spin, as it was then called, was a bad quantum number because the Coulomb force was so strong. Well, John and his colleagues set about to calculate the Z of the contaminant mirror transition that would put the sharp peak at the observed energy. They found Z = 23, that of the vanadium target ! They had discovered the existence of sharp isospin multiplet states in nonmirror nuclei. Dogmas are forced to change, and jargon changes. We now accept the idea that Fermi transition strength is concentrated in a sharp state, the IAS. CVC and PCAC are good buzz acronyms that get you accelerator time from PACs. But the discovery made by Anderson, Wong, McClure, and Bloom still stands as the most important finding in nuclear structure in over a quarter of a century

  13. Polyunsaturated fatty acids synergize with lipid droplet binding thalidomide analogs to induce oxidative stress in cancer cells

    Directory of Open Access Journals (Sweden)

    Madácsi Ramóna

    2010-06-01

    Full Text Available Abstract Background Cytoplasmic lipid-droplets are common inclusions of eukaryotic cells. Lipid-droplet binding thalidomide analogs (2,6-dialkylphenyl-4/5-amino-substituted-5,6,7-trifluorophthalimides with potent anticancer activities were synthesized. Results Cytotoxicity was detected in different cell lines including melanoma, leukemia, hepatocellular carcinoma, glioblastoma at micromolar concentrations. The synthesized analogs are non-toxic to adult animals up to 1 g/kg but are teratogenic to zebrafish embryos at micromolar concentrations with defects in the developing muscle. Treatment of tumor cells resulted in calcium release from the endoplasmic reticulum (ER, induction of reactive oxygen species (ROS, ER stress and cell death. Antioxidants could partially, while an intracellular calcium chelator almost completely diminish ROS production. Exogenous docosahexaenoic acid or eicosapentaenoic acid induced calcium release and ROS generation, and synergized with the analogs in vitro, while oleic acid had no such an effect. Gene expression analysis confirmed the induction of ER stress-mediated apoptosis pathway components, such as GADD153, ATF3, Luman/CREB3 and the ER-associated degradation-related HERPUD1 genes. Tumor suppressors, P53, LATS2 and ING3 were also up-regulated in various cell lines after drug treatment. Amino-phthalimides down-regulated the expression of CCL2, which is implicated in tumor metastasis and angiogenesis. Conclusions Because of the anticancer, anti-angiogenic action and the wide range of applicability of the immunomodulatory drugs, including thalidomide analogs, lipid droplet-binding members of this family could represent a new class of agents by affecting ER-membrane integrity and perturbations of ER homeostasis.

  14. Pre-Steady State Kinetic Investigation of the Incorporation of Anti-Hepatitis B Nucleotide Analogs Catalyzed by Non-Canonical Human DNA Polymerases

    Science.gov (United States)

    Brown, Jessica A.; Pack, Lindsey R.; Fowler, Jason D.; Suo, Zucai

    2011-01-01

    Antiviral nucleoside analogs have been developed to inhibit the enzymatic activities of the hepatitis B virus (HBV) polymerase, thereby preventing the replication and production of HBV. However, the usage of these analogs can be limited by drug toxicity because the 5′-triphosphates of these nucleoside analogs (nucleotide analogs) are potential substrates for human DNA polymerases to incorporate into host DNA. Although they are poor substrates for human replicative DNA polymerases, it remains to be established whether these nucleotide analogs are substrates for the recently discovered human X- and Y-family DNA polymerases. Using pre-steady state kinetic techniques, we have measured the substrate specificity values for human DNA polymerases β, λ, η, ι, κ, and Rev1 incorporating the active forms of the following anti-HBV nucleoside analogs approved for clinical use: adefovir, tenofovir, lamivudine, telbivudine, and entecavir. Compared to the incorporation of a natural nucleotide, most of the nucleotide analogs were incorporated less efficiently (2 to >122,000) by the six human DNA polymerases. In addition, the potential for entecavir and telbivudine, two drugs which possess a 3′-hydroxyl, to become embedded into human DNA was examined by primer extension and DNA ligation assays. These results suggested that telbivudine functions as a chain terminator while entecavir was efficiently extended by the six enzymes and was a substrate for human DNA ligase I. Our findings suggested that incorporation of anti-HBV nucleotide analogs catalyzed by human X- and Y-family polymerases may contribute to clinical toxicity. PMID:22132702

  15. Oxidatively generated DNA/RNA damage in psychological stress states

    DEFF Research Database (Denmark)

    Jørgensen, Anders

    2013-01-01

    age-related somatic disorders. The overall aim of the PhD project was to investigate the relation between psychopathology, psychological stress, stress hormone secretion and oxidatively generated DNA and RNA damage, as measured by the urinary excretion of markers of whole-body DNA/RNA oxidation (8...... between the 24 h urinary cortisol excretion and the excretion of 8-oxodG/8-oxoGuo, determined in the same samples. Collectively, the studies could not confirm an association between psychological stress and oxidative stress on nucleic acids. Systemic oxidatively generated DNA/RNA damage was increased......Both non-pathological psychological stress states and mental disorders are associated with molecular, cellular and epidemiological signs of accelerated aging. Oxidative stress on nucleic acids is a critical component of cellular and organismal aging, and a suggested pathogenic mechanism in several...

  16. Charge state of oxide layer of SIMOX-structures

    CERN Document Server

    Askinazi, A Y; Dmitriev, V A; Miloglyadova, L V

    2001-01-01

    The charge state of the oxide layer of the SIMOX-structures, obtained in the course of forming the oxide layers, bricked up in the silicon volume, through the oxygen ions implantation into the Si, is studied. The charge state of the given structures is studied through the method of the layer-by-layer profiling, which makes it possible to obtain the dependence of the plane zones potential on the oxide layer thickness. It is established, that during the process of the SIMOX-structures formation in the oxide layer near the boundary with the Si there appear defects, responsible for the charge. The radiation from the near-the-ultraviolet (NUV) area without the applied electric field neutralizes the given charge. The simultaneous impact of the NUV-radiation and electric field leads to the formation of significantly positive charge

  17. BENCH-SCALE VISUALIZATION OF DNAPL REMEDIATION PROCESSES IN ANALOG HETEROGENEOUS AQUIFERS: SURFACTANT FLOODS, AND IN SITU OXIDATION USING PERMANGANATE

    Science.gov (United States)

    We have conducted well-controlled DNAPL remediation experiments using surfactants (Aerosol MA and Tween 80) to increase solubility and an oxidant (permanganate) to chemically degrade the DNAPL. Photographs and digital image analysis illustrate previously unobserved interactions b...

  18. Effect of microorganisms on the plutonium oxidation states

    International Nuclear Information System (INIS)

    Lukšienė, Benedikta; Druteikienė, Rūta; Pečiulytė, Dalia; Baltrūnas, Dalis; Remeikis, Vidmantas; Paškevičius, Algimantas

    2012-01-01

    Particular microbes from substrates at the low-level radioactive waste repository in the Ignalina NPP territory were exposed to 239 Pu (IV) at low pH under aerobic conditions. Pu(III) and Pu(IV) were separated and quantitatively evaluated using the modified anion exchange method and alpha spectrometry. Tested bacteria Bacillus mycoides and Serratia marcescens were more effective in Pu reduction than Rhodococcus fascians. Fungi Paecillomyces lilacinus and Absidia spinosa var. spinosa as well as bacterium Rhodococcus fascians did not alter the plutonium oxidation state. - Highlights: ► Particular microbes from low-level radioactive waste repository were exposed to Pu (IV). ► Some tested bacteria induced slight Pu (IV) reduction at low pH under aerobic conditions. ► Tested fungi did not show peculiarities to alter Pu oxidation state. ► The modified radiochemical method was applied to differentiate Pu oxidation states.

  19. Effect of microorganisms on the plutonium oxidation states

    Energy Technology Data Exchange (ETDEWEB)

    Luksiene, Benedikta, E-mail: bena@ar.fi.lt [Center for Physical Sciences and Technology, Savanoriu ave 231, LT-02300 Vilnius (Lithuania); Druteikiene, Ruta [Center for Physical Sciences and Technology, Savanoriu ave 231, LT-02300 Vilnius (Lithuania); Peciulyte, Dalia [Nature Research Centre, Akademijos street 2, LT-08412 Vilnius (Lithuania); Baltrunas, Dalis; Remeikis, Vidmantas [Center for Physical Sciences and Technology, Savanoriu ave 231, LT-02300 Vilnius (Lithuania); Paskevicius, Algimantas [Nature Research Centre, Akademijos street 2, LT-08412 Vilnius (Lithuania)

    2012-03-15

    Particular microbes from substrates at the low-level radioactive waste repository in the Ignalina NPP territory were exposed to {sup 239}Pu (IV) at low pH under aerobic conditions. Pu(III) and Pu(IV) were separated and quantitatively evaluated using the modified anion exchange method and alpha spectrometry. Tested bacteria Bacillus mycoides and Serratia marcescens were more effective in Pu reduction than Rhodococcus fascians. Fungi Paecillomyces lilacinus and Absidia spinosa var. spinosa as well as bacterium Rhodococcus fascians did not alter the plutonium oxidation state. - Highlights: Black-Right-Pointing-Pointer Particular microbes from low-level radioactive waste repository were exposed to Pu (IV). Black-Right-Pointing-Pointer Some tested bacteria induced slight Pu (IV) reduction at low pH under aerobic conditions. Black-Right-Pointing-Pointer Tested fungi did not show peculiarities to alter Pu oxidation state. Black-Right-Pointing-Pointer The modified radiochemical method was applied to differentiate Pu oxidation states.

  20. Bound states for a neutral particle analogous to a quantum dot induced by the non-inertial effects of the Fermi-Walker reference frame

    International Nuclear Information System (INIS)

    Bakke, Knut

    2010-01-01

    We study the appearance of bound states analogous to a quantum dot, proposed by Tan and Inkson (1996) , in the non-relativistic quantum dynamics of a neutral particle with permanent magnetic dipole moment induced by the non-inertial effects of the Fermi-Walker reference frame.

  1. The Apparent Involvement of ANMEs in Mineral Dependent Methane Oxidation, as an Analog for Possible Martian Methanotrophy

    Directory of Open Access Journals (Sweden)

    Victoria J. Orphan

    2011-11-01

    Full Text Available On Earth, marine anaerobic methane oxidation (AOM can be driven by the microbial reduction of sulfate, iron, and manganese. Here, we have further characterized marine sediment incubations to determine if the mineral dependent methane oxidation involves similar microorganisms to those found for sulfate-dependent methane oxidation. Through FISH and FISH-SIMS analyses using 13C and 15N labeled substrates, we find that the most active cells during manganese dependent AOM are primarily mixed and mixed-cluster aggregates of archaea and bacteria. Overall, our control experiment using sulfate showed two active bacterial clusters, two active shell aggregates, one active mixed aggregate, and an active archaeal sarcina, the last of which appeared to take up methane in the absence of a closely-associated bacterial partner. A single example of a shell aggregate appeared to be active in the manganese incubation, along with three mixed aggregates and an archaeal sarcina. These results suggest that the microorganisms (e.g., ANME-2 found active in the manganese-dependent incubations are likely capable of sulfate-dependent AOM. Similar metabolic flexibility for Martian methanotrophs would mean that the same microbial groups could inhabit a diverse set of Martian mineralogical crustal environments. The recently discovered seasonal Martian plumes of methane outgassing could be coupled to the reduction of abundant surface sulfates and extensive metal oxides, providing a feasible metabolism for present and past Mars. In an optimistic scenario Martian methanotrophy consumes much of the periodic methane released supporting on the order of 10,000 microbial cells per cm2 of Martian surface. Alternatively, most of the methane released each year could be oxidized through an abiotic process requiring biological methane oxidation to be more limited. If under this scenario, 1% of this methane flux were oxidized by biology in surface soils or in subsurface aquifers (prior to

  2. Shifts in oxidation states of cerium oxide nanoparticles detected inside intact hydrated cells and organelles

    Energy Technology Data Exchange (ETDEWEB)

    Szymanski, Craig J.; Munusamy, Prabhakaran; Mihai, Cosmin; Xie, Yumei; Hu, Dehong; Gilles, Marry K.; Tyliszczak, T.; Thevuthasan, Suntharampillai; Baer, Donald R.; Orr, Galya

    2015-09-01

    Cerium oxide nanoparticles (CNPs) have been shown to induce diverse biological effects, ranging from toxic to beneficial. The beneficial effects have been attributed to the potential antioxidant activity of CNPs via certain redox reactions, depending on their oxidation state or Ce3+/Ce4+ ratio. However, this ratio is strongly dependent on the environment and age of the nanoparticles and it is unclear whether and how the complex intracellular environment impacts this ratio and the possible redox reactions of CNPs. To identify any changes in the oxidation state of CNPs in the intracellular environment and better understand their intracellular reactions, we directly quantified the oxidation states of CNPs outside and inside intact hydrated cells and organelles using correlated scanning transmission x-ray and super resolution fluorescence microscopies. By analyzing hundreds of small CNP aggregates, we detected a shift to a higher Ce3+/Ce4+ ratio in CNPs inside versus outside the cells, indicating a net reduction of CNPs in the intracellular environment. We further found a similar ratio in the cytoplasm and in the lysosomes, indicating that the net reduction occurs earlier in the internalization pathway. Together with oxidative stress and toxicity measurements, our observations identify a net reduction of CNPs in the intracellular environment, which is consistent with their involvement in potentially beneficial oxidation reactions, but also point to interactions that can negatively impact the health of cells.

  3. Relationships among oxidation-reduction and acid-base properties of the actinides in high oxidation states

    International Nuclear Information System (INIS)

    Morss, L.R.

    1992-01-01

    The first chemical identification of plutonium, its subsequent isolation on the macroscopic scale, and more recent chemical separation schemes were achieved by taking advantage of the differences among the oxidation states of uranium, neptunium, and plutonium. Many acid-base properties modify the relative stabilities of oxidation states of the actinides. In the solid state, strongly basic compounds such as Cs 2 O yield complex oxides with oxidation states of Np(VII), Pu(VI), and Am(VI) whereas more acidic compounds such as CsF yield complex fluorides with lower oxidation states. In aqueous solution, high basicity and strongly covalent complexes favor high oxidation states. In nonaqueous solvent systems, high acidity generally favors low oxidation states. This paper elucidates and attempts to interpret the effects of these acid-base properties in a systematic fashion

  4. Analog earthquakes

    International Nuclear Information System (INIS)

    Hofmann, R.B.

    1995-01-01

    Analogs are used to understand complex or poorly understood phenomena for which little data may be available at the actual repository site. Earthquakes are complex phenomena, and they can have a large number of effects on the natural system, as well as on engineered structures. Instrumental data close to the source of large earthquakes are rarely obtained. The rare events for which measurements are available may be used, with modfications, as analogs for potential large earthquakes at sites where no earthquake data are available. In the following, several examples of nuclear reactor and liquified natural gas facility siting are discussed. A potential use of analog earthquakes is proposed for a high-level nuclear waste (HLW) repository

  5. Diversity of Chemical Bonding and Oxidation States in MS4 Molecules of Group 8 Elements.

    Science.gov (United States)

    Huang, Wei; Jiang, Ning; Schwarz, W H Eugen; Yang, Ping; Li, Jun

    2017-08-04

    The geometric and electronic ground-state structures of 30 isomers of six MS 4 molecules (M=Group 8 metals Fe, Ru, Os, Hs, Sm, and Pu) have been studied by using quantum-chemical density functional theory and correlated wavefunction approaches. The MS 4 species were compared to analogous MO 4 species recently investigated (W. Huang, W.-H. Xu, W. H. E. Schwarz, J. Li, Inorg. Chem. 2016, 55, 4616). A metal oxidation state (MOS) with a high value of eight appeared in the low-spin singlet T d geometric species (Os,Hs)S 4 and (Ru,Os,Hs)O 4 , whereas a low MOS of two appeared in the high-spin septet D 2d species Fe(S 2 ) 2 and (slightly excited) metastable Fe(O 2 ) 2 . The ground states of all other molecules had intermediate MOS values, with S 2- , S 2 2- , S 2 1- (and O 2- , O 1- , O 2 2- , O 2 1- ) ligands bonded by ionic, covalent, and correlative contributions. The known tendencies toward lower MOS on going from oxides to sulfides, from Hs to Os to Ru, and from Pu to Sm, and the specific behavior of Fe, were found to arise from the different atomic orbital energies and radii of the (n-1)p core and (n-1)d and (n-2)f valence shells of the metal atoms in row n of the periodic table. The comparative results of the electronic and geometric structures of the MO 4 and MS 4 species provides insight into the periodicity of oxidation states and bonding. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. ESD analog circuits and design

    CERN Document Server

    Voldman, Steven H

    2014-01-01

    A comprehensive and in-depth review of analog circuit layout, schematic architecture, device, power network and ESD design This book will provide a balanced overview of analog circuit design layout, analog circuit schematic development, architecture of chips, and ESD design.  It will start at an introductory level and will bring the reader right up to the state-of-the-art. Two critical design aspects for analog and power integrated circuits are combined. The first design aspect covers analog circuit design techniques to achieve the desired circuit performance. The second and main aspect pres

  7. Mono(pyridine-N-oxide) analog of DOTA as a suitable organic reagent for a sensitive and selective fluorimetric determination of Ln(III) ions

    Energy Technology Data Exchange (ETDEWEB)

    Vanek, Jakub [Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic); Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Lubal, Premysl, E-mail: lubal@chemi.muni.cz [Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic); Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Sevcikova, Romana [Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic); Polasek, Miloslav; Hermann, Petr [Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40, Prague (Czech Republic)

    2012-08-15

    The mono(pyridine-N-oxide) analog of the H{sub 4}dota macrocylic ligand, H{sub 3}do3a-py{sup NO}, is capable of forming thermodynamically stable and kinetically inert Ln(III) complexes. Its Eu(III) and Tb(III) complexes display a strong long-lived fluorescence as a result of the antenna effect of the pyridine-N-oxide fluorophore in the reagent. It is shown that H{sub 3}do3a-py{sup NO} can be used as a fluorogenic reagent for the determination of Eu(III) and Tb(III) at pH 6.5 and c{sub L}=1 mM. At an excitation wavelength of 286 nm, the emission maxima are 615 nm (Eu(III)-complex), and 547 nm (Tb(III)complex). Detection limits are at concentrations around 1.0 {mu}M and linearity of the method spans over 2 orders of magnitude. The method was applied to artificial and real samples (spiked mineral waters, extracts from cathode ray tube luminophore dust) and gave satisfactory results. The method is simple, rapid, and hardly interfered by other metal ions. - Graphical Abstract: A DOTA-like ligand with pyridine-N-oxide pendant arm is used for a quick, selective and sensitive determination of Eu{sup 3+} and Tb{sup 3+} ions through sensitized emission with excitation at 286 nm. The presented fluorimetric method is not interfered by transition metal or other lanthanide(III) ions and has a high dynamic range. Highlights: Black-Right-Pointing-Pointer Quick, selective and sensitive determination of Eu{sup 3+}/Tb{sup 3+} ions was developed. Black-Right-Pointing-Pointer Sensitized emission with excitation at 286 nm through pyridine-N-oxide pendant arm. Black-Right-Pointing-Pointer No interference of transition metal or other Ln(III) ions within high dynamic range.

  8. Oxidative Stress and Heart Failure in Altered Thyroid States

    Directory of Open Access Journals (Sweden)

    Pallavi Mishra

    2012-01-01

    Full Text Available Increased or reduced action of thyroid hormone on certain molecular pathways in the heart and vasculature causes relevant cardiovascular derangements. It is well established that hyperthyroidism induces a hyperdynamic cardiovascular state, which is associated with a faster heart rate, enhanced left ventricular systolic and diastolic function whereas hypothyroidism is characterized by the opposite changes. Hyperthyroidism and hypothyroidism represent opposite clinical conditions, albeit not mirror images. Recent experimental and clinical studies have suggested the involvement of ROS tissue damage under altered thyroid status. Altered-thyroid state-linked changes in heart modify their susceptibility to oxidants and the extent of the oxidative damage they suffer following oxidative challenge. Chronic increase in the cellular levels of ROS can lead to a catastrophic cycle of DNA damage, mitochondrial dysfunction, further ROS generation and cellular injury. Thus, these cellular events might play an important role in the development and progression of myocardial remodeling and heart failure in altered thyroid states (hypo- and hyper-thyroidism. The present review aims at elucidating the various signaling pathways mediated via ROS and their modulation under altered thyroid state and the possibility of antioxidant therapy.

  9. Evolution of the Oxidation State of the Earth's Mantle

    Science.gov (United States)

    Danielson, L. R.; Righter, K.; Keller, L.; Christoffersen, E.; Rahman, Z.

    2015-01-01

    The oxidation state of the Earth's mantle during formation remains an unresolved question, whether it was constant throughout planetary accretion, transitioned from reduced to oxidized, or from oxidized to reduced. We investigate the stability of Fe3(+) at depth, in order to constrain processes (water, late accretion, dissociation of FeO) which may reduce or oxidize the Earth's mantle. In our previous experiments on shergottite compositions, variable fO2, T, and P less than 4 GPa, Fe3(+)/sigma Fe decreased slightly with increasing P, similar to terrestrial basalt. For oxidizing experiments less than 7GPa, Fe3(+)/sigma Fe decreased as well, but it's unclear from previous modelling whether the deeper mantle could retain significant Fe3(+). Our current experiments expand our pressure range deeper into the Earth's mantle and focus on compositions and conditions relevant to the early Earth. Preliminary multi-anvil experiments with Knippa basalt as the starting composition were conducted at 5-7 GPa and 1800 C, using a molybdenum capsule to set the fO2 near IW, by buffering with Mo-MoO3. TEM and EELS analyses revealed the run products quenched to polycrystalline phases, with the major phase pyroxene containing approximately equal to Fe3(+)/2(+). Experiments are underway to produce glassy samples that can be measured by EELS and XANES, and are conducted at higher pressures.

  10. Corrosion-product transport, oxidation state and remedial measures

    International Nuclear Information System (INIS)

    Sawicki, J.A.; Brett, M.E.; Tapping, R.L.

    1998-10-01

    The issues associated with monitoring and controlling corrosion-product transport (CPT) in the balance-of-plant (BOP) and steam generators (SG) of CANDU stations are briefly reviewed. Efforts are focused on minimizing corrosion of carbon steel, which is used extensively in the CANDU primary and secondary systems. Emphasis is placed on the corrosion-product oxidation state as a monitor of water chemistry effectiveness and as a monitor of system corrosion effects. The discussion is based mostly on the results of observations from Ontario Hydro plants, and their comparisons with pressurized-water reactors. The effects of low oxygen and elevated hydrazine chemistry are reviewed, as well as the effects of layup and various startup conditions. Progress in monitoring electrochemical potential (ECP) at Ontario Hydro plants and its relationship to the oxidation state of corrosion products is reviewed. Observations on CPT on the primary side of SGs are also discussed. (author)

  11. Corrosion-product transport, oxidation state and remedial measures

    International Nuclear Information System (INIS)

    Sawicki, J.A.; Brett, M.E.; Tapping, R.L.

    1998-01-01

    The issues associated with monitoring and controlling corrosion-product transport (CPT) in the balance-of-plant (BOP) and steam generators (SG) of CANDU stations are briefly reviewed. The efforts are focused on minimizing corrosion of carbon steel, which is used extensively in the CANDU primary and secondary systems. Emphasis is placed on the corrosion-product oxidation state as a monitor of water chemistry effectiveness, and as a monitor of system corrosion effects. The discussion is based mostly on the results and observations from Ontario Hydro plants, and their comparisons with PWRs. The effects of low oxygen and elevated hydrazine chemistry are reviewed, as well as the effects of lay-up and various start-up conditions. Progress in monitoring electrochemical potential (ECP) at Ontario Hydro plants and its relationship to the oxidation state of corrosion products is reviewed. Observations on corrosion-product transport on the primary side of steam generators are also discussed. (author)

  12. Influence of oxidation state on the pH dependence of hydrous iridium oxide films

    International Nuclear Information System (INIS)

    Steegstra, Patrick; Ahlberg, Elisabet

    2012-01-01

    Many electrochemical reactions taking place in aqueous solution consume or produce protons. The pH in the diffusion layer can therefore be significantly altered during the reaction and there is a need for in situ pH measurements tracing this near surface pH. In the present paper the rotating ring disc technique was used to measure near surface pH changes during oxygen reduction, utilising hydrous iridium oxide as the pH sensing probe. Before such experiments a good understanding of the pH sensing properties of these films is required and the impact of the oxidation state of the film on the pH sensing properties was investigated as well as the influence of solution redox species. The pH sensitivity (depicted by dE/dpH) was found to depend on the average oxidation state of the film in a manner resembling the cyclic voltammetry response. In all cases the pH response is “supernernstian” with more than one proton per electron. The origin of this behaviour is discussed in the context of acid-base properties of the film and the existence of both hydrous and anhydrous oxide phases. The pH response depends also on the redox properties of the solution but can be optimised for various purposes by conditioning the film at different potentials. This was clearly illustrated by adding hydrogen peroxide, an intermediate in the oxygen reduction reaction, to the solution. It was shown that hydrous iridium oxide can be used as a reliable in situ pH sensor provided that care is taken to optimise the oxidation state of the film.

  13. Pentavalent Uranium Chemistry - Synthetic Pursuit Of A Rare Oxidation State

    Energy Technology Data Exchange (ETDEWEB)

    Graves, Christopher R [Los Alamos National Laboratory; Kiplinger, Jaqueline L [Los Alamos National Laboratory

    2009-01-01

    This feature article presents a comprehensive overview of pentavalent uranium systems in non-aqueous solution with a focus on the various synthetic avenues employed to access this unusual and very important oxidation state. Selected characterization data and theoretical aspects are also included. The purpose is to provide a perspective on this rapidly evolving field and identify new possibilities for future developments in pentavalent uranium chemistry.

  14. Study of uranium oxidation states in geological material.

    Science.gov (United States)

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

    2013-10-01

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

  15. Analogous β-Carboline Alkaloids Harmaline and Harmine Ameliorate Scopolamine-Induced Cognition Dysfunction by Attenuating Acetylcholinesterase Activity, Oxidative Stress, and Inflammation in Mice

    Science.gov (United States)

    Li, Shu-Ping; Wang, Yu-Wen; Qi, Sheng-Lan; Zhang, Yun-Peng; Deng, Gang; Ding, Wen-Zheng; Ma, Chao; Lin, Qi-Yan; Guan, Hui-Da; Liu, Wei; Cheng, Xue-Mei; Wang, Chang-Hong

    2018-01-01

    The analogous β-carboline alkaloids, harmaline (HAL) and harmine (HAR), possess a variety of biological properties, including acetylcholinesterase (AChE) inhibitory activity, antioxidant, anti-inflammatory, and many others, and have great potential for treating Alzheimer’s disease (AD). However, studies have showed that the two compounds have similar structures and in vitro AChE inhibitory activities but with significant difference in bioavailability. The objective of this study was to comparatively investigate the effects of HAL and HAR in memory deficits of scopolamine-induced mice. In the present study, mice were pretreated with HAL (2, 5, and 10 mg/kg), HAR (10, 20, and 30 mg/kg) and donepezil (5 mg/kg) by intragastrically for 7 days, and were daily intraperitoneal injected with scopolamine (1 mg/kg) to induce memory deficits and then subjected to behavioral evaluation by Morris water maze. To further elucidate the underlying mechanisms of HAL and HAR in improving learning and memory, the levels of various biochemical factors and protein expressions related to cholinergic function, oxidative stress, and inflammation were examined. The results showed that HAL and HAR could effectively ameliorate memory deficits in scopolamine-induced mice. Both of them exhibited an enhancement in cholinergic function by inhibiting AChE and inducing choline acetyltransferase (ChAT) activities, and antioxidant defense via increasing the antioxidant enzymes activities of superoxide dismutase and glutathione peroxidase, and reducing maleic diadehyde production, and anti-inflammatory effects through suppressing myeloperoxidase, tumor necrosis factor α, and nitric oxide as well as modulation of critical neurotransmitters such as acetylcholine (ACh), choline (Ch), L-tryptophan (L-Trp), 5-hydroxytryptamine (5-HT), γ-aminobutyric acid (γ-GABA), and L-glutamic acid (L-Glu). Furthermore, the regulations of HAL on cholinergic function, inflammation, and neurotransmitters were more

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

    International Nuclear Information System (INIS)

    Wang Bo; Liu Dejun; Yao Jun

    2010-01-01

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

  17. Studies of Tc oxidation states in humic acid solutions

    International Nuclear Information System (INIS)

    Wang Bo; Liu Dejun; Yao Jun

    2011-01-01

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

  18. Phase Behavior and Equations of State of the Actinide Oxides

    Science.gov (United States)

    Chidester, B.; Pardo, O. S.; Panero, W. R.; Fischer, R. A.; Thompson, E. C.; Heinz, D. L.; Prescher, C.; Prakapenka, V. B.; Campbell, A.

    2017-12-01

    The distribution of the long-lived heat-producing actinide elements U and Th in the deep Earth has important implications for the dynamics of the mantle and possibly the energy budget of Earth's core. The low shear velocities of the Large Low-Shear Velocity Provinces (LLSVPs) on the core-mantle boundary suggests that these regions are at least partially molten and may contain concentrated amounts of the radioactive elements, as well as other large cations such as the rare Earth elements. As such, by exploring the phase behavior of actinide-bearing minerals at extreme conditions, some insight into the mineralogy, formation, and geochemical and geodynamical effects of these regions can be gained. We have performed in situ high-pressure, high-temperature synchrotron X-ray diffraction experiments and calculations on two actinide oxide materials, UO2 and ThO2, to determine their phase behavior at the extreme conditions of the lower mantle. Experiments on ThO2 reached 60 GPa and 2500 K, and experiments on UO2 reached 95 GPa and 2500 K. We find that ThO2 exists in the fluorite-type structure to 20 GPa at high temperatures, at which point it transforms to the high-pressure cotunnite-type structure and remains thus up to 60 GPa. At room temperature, an anomalous expansion of the fluorite structure is observed prior to the transition, and may signal anion sub-lattice disorder. Similarly, UO2 exists in the fluorite-type structure at ambient conditions and up to 28 GPa at high temperatures. Above these pressures, we have observed a previously unidentified phase of UO2 with a tetragonal structure as the lower-temperature phase and the cotunnite-type phase at higher temperatures. Above 78 GPa, UO2 undergoes another transition or possible dissociation into two separate oxide phases. These phase diagrams suggest that the actinides could exist as oxides in solid solution with other analogous phases (e.g. ZrO2) in the cotunnite-type structure throughout much of Earth's lower mantle.

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

    International Nuclear Information System (INIS)

    Yamashita, Toshiyuki

    1988-03-01

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

  20. Optoelectronic properties of valence-state-controlled amorphous niobium oxide

    Science.gov (United States)

    Onozato, Takaki; Katase, Takayoshi; Yamamoto, Akira; Katayama, Shota; Matsushima, Koichi; Itagaki, Naho; Yoshida, Hisao; Ohta, Hiromichi

    2016-06-01

    In order to understand the optoelectronic properties of amorphous niobium oxide (a-NbO x ), we have investigated the valence states, local structures, electrical resistivity, and optical absorption of a-NbO x thin films with various oxygen contents. It was found that the valence states of Nb ion in a-NbO x films can be controlled from 5+  to 4+  by reducing oxygen pressure during film deposition at room temperature, together with changing the oxide-ion arrangement around Nb ion from Nb2O5-like to NbO2-like local structure. As a result, a four orders of magnitude reduction in the electrical resistivity of a-NbO x films was observed with decreasing oxygen content, due to the carrier generation caused by the appearance and increase of an oxygen-vacancy-related subgap state working as an electron donor. The tunable optoelectronic properties of a-NbO x films by valence-state-control with oxygen-vacancy formation will be useful for potential flexible optoelectronic device applications.

  1. Predicting spent fuel oxidation states in a tuff repository

    International Nuclear Information System (INIS)

    Einziger, R.E.; Woodley, R.E.

    1987-01-01

    Nevada Nuclear Waste Storage Investigations Project (NNWSI) is studying the suitability of the tuffaceous rocks at Yucca Mountain as a waste repository for spent fuel disposal. The oxidation state of the LWR spent fuel in the moist air environment of a tuff repository could be a significant factor in determining its leaching and dissolution characteristics. Predictions as to which oxidation states would be present are important in analyzing such a repository and thus the present study was undertaken. A set of TGA (thermogravimetric analysis) tests were conducted on well-controlled samples of irradiated PWR fuel with time and temperature as the only variables. The tests were conducted between 140 and 225 0 C for a duration up to 2200 hours. The weight gain curves were analyzed in terms of diffusion through a layer of U 3 O 7 , diffusion into the grains to form a solid solution, a simplified empirical representation of a combination of grain boundary diffusion and bulk grain oxidation. Reaction rate constants were determined in each case, but analysis of these data could not establish a definitive mechanism. 21 refs., 10 figs., 3 tabs

  2. The effect of ionizing radiation on analog characteristics of MOSFET

    International Nuclear Information System (INIS)

    Ren Diyuan; Yu Xuefeng; Lu Wu; Gao Wenyu; Fan Long; Zhang Guoqiang; Yan Rongliang

    1994-01-01

    The effects of 60 Co γ-ray on the linearity and output characteristics of MOSFETs were investigated. The relations of oxide-trapped charge and Si/SiO 2 interface state density to the decrease of mobility μ-bar and transconductance g m , and the shift of the output curves for both P-MOSFETs and N-MOSFETs were qualitatively described. It was shown that degradation of analog characteristics, for P-MOSFETs, resulted from both oxide-trapped charge and interface state, but the degradation for N-MOSFETs was mainly due to the increase of radiation induced Si-SiO 2 interface state density

  3. The oxidation state of sulfur in apatite: A new oxybarometer?

    Science.gov (United States)

    Fiege, A.; Konecke, B.; Kim, Y.; Simon, A. C.; Becker, U.; Parat, F.

    2016-12-01

    Oxygen fugacity (fO2) of magmatic and hydrothermal systems influences, for instance, crystallization and degassing processes as well as metal solubilities in melts and fluids. Apatite is a ubiquitous mineral in magmatic and hydrothermal environments that can record and preserve volatile zonation. It can contain several thousand μg/g of the redox sensitive element sulfur (S), making S-in-apatite a potential fO2 sensor. Despite the polyvalent properties of S (e.g., S2-, S4+, S6+), the oxidation state and incorporation mechanisms of S in the apatite structure are poorly understood. In this study, the oxidation state of S-in-apatite as a function of fO2 is investigated using X-ray absorption near-edge structures (XANES) spectroscopy at the S K-edge. Apatites crystallized from lamproitic melts at 1000°C, 300 MPa and over a broad range of fO2 and sulfur fugacities (fS2) were measured. Peaks corresponding to S6+ ( 2482 eV), S4+ ( 2478 eV) and S2- ( 2470 eV) were identified in apatite. The integrated S6+/STotal (STotal = S6+ + S4+ + S2-) peak area ratios show a distinct positive correlation with fO2, increasing from 0.17 at FMQ+0 to 0.96 at FMQ+3. Ab-initio calculations were performed to further understand the energetics and geometry of incorporation of S6+, S4+ and S2- into the apatite (F-, Cl-, OH-) end-members. The results confirm that apatite can contain three different oxidations states of S (S6+, S4+, S2-) as a function of fO2. This makes apatite probably the first geologically relevant mineral to incorporate reduced (S2-), intermediate (S4+), and oxidized (S6+) S in variable proportions. We emphasize that the strong dependence of the S oxidation state in apatite as a function of fO2 is also coupled with changing S content of apatite and co-existing melt (i.e., with changing fS2), resulting in a complex correlation between [1] apatite-melt (or fluid) partitioning, [2] redox conditions and [3] the melt and/or fluid composition, making the application of previously

  4. Chelation and stabilization of berkelium in oxidation state +IV

    Science.gov (United States)

    Deblonde, Gauthier J.-P.; Sturzbecher-Hoehne, Manuel; Rupert, Peter B.; An, Dahlia D.; Illy, Marie-Claire; Ralston, Corie Y.; Brabec, Jiri; de Jong, Wibe A.; Strong, Roland K.; Abergel, Rebecca J.

    2017-09-01

    Berkelium (Bk) has been predicted to be the only transplutonium element able to exhibit both +III and +IV oxidation states in solution, but evidence of a stable oxidized Bk chelate has so far remained elusive. Here we describe the stabilization of the heaviest 4+ ion of the periodic table, under mild aqueous conditions, using a siderophore derivative. The resulting Bk(IV) complex exhibits luminescence via sensitization through an intramolecular antenna effect. This neutral Bk(IV) coordination compound is not sequestered by the protein siderocalin—a mammalian metal transporter—in contrast to the negatively charged species obtained with neighbouring trivalent actinides americium, curium and californium (Cf). The corresponding Cf(III)-ligand-protein ternary adduct was characterized by X-ray diffraction analysis. Combined with theoretical predictions, these data add significant insight to the field of transplutonium chemistry, and may lead to innovative Bk separation and purification processes.

  5. The thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide ores. XI. Solubility of synthetic chalcomenite analog and zinc selenite at 25°C

    Science.gov (United States)

    Charykova, M. V.; Krivovichev, V. G.; Ivanova, N. M.; Semenova, V. V.

    2015-12-01

    The aim of this study is the synthesis of CuSeO3·2H2O (chalcomenite analog), ZnSeO3·2H2O, and ZnSeO3·H2O and the investigation of their solubility in water. CuSeO3·2H2O has been synthesized from solutions of Cu nitrate and Na selenite, while Zn selenites were synthesized from solutions of Zn nitrate and Na selenite. The samples obtained have been examined with X-ray diffraction and infrared and Raman spectroscopy. The solubility has been determined using the isothermal saturation method in ampoules at 25°C. The solubility has been calculated using the Geochemist's Workbench (GMB 9.0) software package. Solubility products have been calculated for CuSeO3·2H2O (10-10.63), ZnSeO3·2H2O (10-8.35), and ZnSeO3·H2O (10-7.96). The database used comprises thermodynamic characteristics of 46 elements, 47 base particles, 48 redox pairs, 551 particles in solution, and 624 solid phases. The Eh-pH diagrams of the Zn-Se-H2O and Cu-Se-H2O systems were plotted for the average contents of these elements in underground water in oxidation zones of sulfide deposits.

  6. The dissolution rate of UO2 in the alkaline regime under oxidizing conditions using a simplified ground water analog

    International Nuclear Information System (INIS)

    Leider, H.R.; Nguyen, S.N.; Weed, H.C.; Steward, S.A.

    1992-01-01

    The major factor controlling the long term release of radionuclides from spent fuel in a geologic repository is the leaching/dissolution by groundwater of the UO 2 matrix, since more than 90% of the radionuclide waste is contained in the fuel matrix. The objective of this investigation is to provide experimental dissolution rates for UO 2 samples which can be used to develop a mechanistic release model (or models) for UO 2+x (x≥0) under repository conditions. Several types of data will be obtained from this study: (1) the dissolution rates of UO 2 as a function of pI-L temperature, carbonate and oxygen fugacity; (2) the comparison of the steady state dissolution rates of ''not-reduced'' versus ''reduced'' UO 2 samples and of single crystal versus polycrystalline UO 2 under identical experimental conditions; (3) the pre- and post-test surface analyses of the samples to provide information on the surface phases that may be formed under experimental conditions

  7. Microscopic description of isobaric-analog-state transitions induced by 25-, 35-, and 45-MeV protons

    International Nuclear Information System (INIS)

    Doering, R.R.; Patterson, D.M.; Galonsky, A.

    1975-01-01

    Differential cross sections have been measured for (p, n) reactions to the isobaric analogs of the targets 48 Ca, 90 Zr, 120 Sn, and 208 Pb at proton bombarding energies of 25, 35, and 45 MeV. The isospin-flip strength of a phenomenological nucleon-nucleon force has been determined with microscopic distorted-wave calculations including the ''knockon'' exchange amplitude. A realistic G-matrix effective interaction also provides a reasonable account of the observed cross sections, particularly at the higher proton energies

  8. Synthesis and characterization of ruthenium fluorides and oxide fluorides with high oxidation states

    International Nuclear Information System (INIS)

    Meublat, L.

    1989-10-01

    The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO 2 and tetroxide RuO 4 . Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO 4 with CIF 3 enabled us to prepare chloryl hexafluororuthenate (V), CIO 2 + RuF 6 - , a new compound well identified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF 2 with RuO 4 gave the oxide tetrafluoride RuOF 4 , the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (70 0 C) of RuOF 4 is presumably RuF 4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF 2 with RuO 2 probably leads to the formation of the new oxide fluoride RuO 2 F 4 . Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds [fr

  9. Synthesis and characterization of ruthenium fluorides and oxide fluorides with high oxidation states

    International Nuclear Information System (INIS)

    Meublat, L.

    1989-01-01

    The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO 2 and tetroxide RuO 4 . Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO 4 with CIF 3 enabled us to prepare chloryl hexafluororuthenate (V), ClO 2 + RuF 6 - , a new compound well idendified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF 2 with RuO 4 gave the oxide tetrafluoride RuOF 4 , the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (70 0 C) of RuOF 4 is presumably RuF 4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF 2 with RuO 2 probably leads to the formation of the new oxide fluoride RuO 2 F 4 . Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds [fr

  10. Intestinal Oxidative State Can Alter Nutrient and Drug Bioavailability

    Directory of Open Access Journals (Sweden)

    Faria Ana

    2009-01-01

    Full Text Available Organic cations (OCs are substances of endogenous (e.g., dopamine, choline or exogenous (e.g., drugs like cimetidine origin that are positively charged at physiological ph. since many of these compounds can not pass the cell membrane freely, their transport in or out of cells must be mediated by specific transport systems. Transport by organic cation transporters (OCTs can be regulated rapidly by altering their trafficking and/or affinities in response to stimuli. However, for example, a specific disease could lead to modifications in the expression of OCTs. Chronic exposure to oxidative stress has been suggested to alter regulation and functional activity of proteins through several pathways. According to results from a previous work, oxidation-reduction pathways were thought to be involved in intestinal organic cation uptake modulation. The present work was performed in order to evaluate the influence of oxidative stressors, especially glutathione, on the intestinal organic cation absorption. For this purpose, the effect of compounds with different redox potential (glutathione, an endogenous antioxidant, and procyanidins, diet antioxidants was assessed on MPP+ (1-methyl-4-phenylpyridinium iodide uptake in an enterocyte cell line (Caco-2. Caco-2 cells were subcultured with two different media conditions (physiological: 5 mM glucose, referred as control cells; and high-glucose: 25 mM glucose, referred as HG cells. In HG cells, the uptake was significantly lower than in control cells. Redox changing interventions affected Mpp+ uptake, both in control and in high-glucose Caco-2 cells. Cellular glutathione levels could have an important impact on membrane transporter activity. The results indicate that modifications in the cellular oxidative state modulate MPP+ uptake by Caco-2 cells. Such modifications may reflect in changes of nutrient and drug bioavailability.

  11. Persistence of oxidation state III of gold in thione coordination

    Science.gov (United States)

    Jääskeläinen, Sirpa; Koskinen, Laura; Kultamaa, Matti; Haukka, Matti; Hirva, Pipsa

    2017-05-01

    Ligands N,N'-tetramethylthiourea and 2-mercapto-1-methyl-imidazole form stable Au(III) complexes [AuCl3(N,N'-tetramethylthiourea)] (1) and [AuCl3(2-mercapto-1-methyl-imidazole)] (2) instead of reducing the Au(III) metal center into Au(I), which would be typical for the attachment of sulfur donors. Compounds 1 and 2 were characterized by spectroscopic methods and by X-ray crystallography. The spectroscopic details were explained by simulation of the UV-Vis spectra via the TD-DFT method. Additionally, computational DFT studies were performed in order to find the reason for the unusual oxidation state in the crystalline materials. The preference for Au(III) can be explained via various weak intra- and intermolecular interactions present in the solid state structures. The nature of the interactions was further investigated by topological charge density analysis via the QTAIM method.

  12. X-ray structure of a transition state analog complex reveals the molecular origins of the catalytic power and substrate specificity of acetylcholinesterase

    Energy Technology Data Exchange (ETDEWEB)

    Harel, M.; Silman, I. [Weizmann Inst. of Science, Rehovot (Israel); Quinn, D.M.; Nair, H.K. [Univ. of Iowa, Iowa City, IA (United States); Sussman, J.L. [Weizmann Inst. of Science, Rehovot (Israel)]|[Brookhaven National Lab., Upton, NY (United States)

    1996-03-13

    The structure of a complex of Torpedo californica acetylcholinesterase with the transition state analog inhibitor m-(N, N,N-trimethylammonio)-2,2,2-trifluoroacetophenone has been solved by X-ray crystallographic methods to 2.8 A resolution. Since the inhibitor binds to the enzyme about 10{sup 10}-fold more tightly than the substrate acetylcholine, this complex provides a visual accounting of the enzyme-ligand interactions that provide the molecular basis for the catalytic power of acetylcholinesterase. The acetyl ester hydrolytic specificity of the enzyme is revealed by the interaction of the CF{sub 3} function of the transition state analog with a concave binding site comprised of the residues G119, W233, F288, F290, and F331. The highly geometrically convergent array of enzyme-ligand interactions visualized in the complex described herein envelopes the acylation transition state and sequesters it from solvent, this being consistent with the location of the active site at the bottom of a deep and narrow gorge. 82 refs., 5 figs.

  13. Proteomic indicators of oxidation and hydration state in colorectal cancer

    Directory of Open Access Journals (Sweden)

    Jeffrey M. Dick

    2016-07-01

    Full Text Available New integrative approaches are needed to harness the potential of rapidly growing datasets of protein expression and microbial community composition in colorectal cancer. Chemical and thermodynamic models offer theoretical tools to describe populations of biomacromolecules and their relative potential for formation in different microenvironmental conditions. The average oxidation state of carbon (ZC can be calculated as an elemental ratio from the chemical formulas of proteins, and water demand per residue ( ${\\overline{n}}_{{\\mathrm{H}}_{2}\\mathrm{O}}$ n ¯ H 2 O is computed by writing the overall formation reactions of proteins from basis species. Using results reported in proteomic studies of clinical samples, many datasets exhibit higher mean ZC or ${\\overline{n}}_{{\\mathrm{H}}_{2}\\mathrm{O}}$ n ¯ H 2 O of proteins in carcinoma or adenoma compared to normal tissue. In contrast, average protein compositions in bacterial genomes often have lower ZC for bacteria enriched in fecal samples from cancer patients compared to healthy donors. In thermodynamic calculations, the potential for formation of the cancer-related proteins is energetically favored by changes in the chemical activity of H2O and fugacity of O2 that reflect the compositional differences. The compositional analysis suggests that a systematic change in chemical composition is an essential feature of cancer proteomes, and the thermodynamic descriptions show that the observed proteomic transformations in host tissue could be promoted by relatively high microenvironmental oxidation and hydration states.

  14. Composition and oxidation state of sulfur in atmospheric particulate matter

    Directory of Open Access Journals (Sweden)

    A. F. Longo

    2016-10-01

    Full Text Available The chemical and physical speciation of atmospheric sulfur was investigated in ambient aerosol samples using a combination of sulfur near-edge x-ray fluorescence spectroscopy (S-NEXFS and X-ray fluorescence (XRF microscopy. These techniques were used to determine the composition and oxidation state of sulfur in common primary emission sources and ambient particulate matter collected from the greater Atlanta area. Ambient particulate matter samples contained two oxidation states: S0 and S+VI. Ninety-five percent of the individual aerosol particles (> 1 µm analyzed contain S0. Linear combination fitting revealed that S+VI in ambient aerosol was dominated by ammonium sulfate as well as metal sulfates. The finding of metal sulfates provides further evidence for acidic reactions that solubilize metals, such as iron, during atmospheric transport. Emission sources, including biomass burning, coal fly ash, gasoline, diesel, volcanic ash, and aerosolized Atlanta soil, and the commercially available bacterium Bacillus subtilis, contained only S+VI. A commercially available Azotobacter vinelandii sample contained approximately equal proportions of S0 and S+VI. S0 in individual aerosol particles most likely originates from primary emission sources, such as aerosolized bacteria or incomplete combustion.

  15. Anticancer effects of monocarbonyl analogs of curcumin: oxidative stress, nuclear translocation and modulation of AP-1 and NF-κB

    Directory of Open Access Journals (Sweden)

    Brian Adams

    2015-01-01

    Full Text Available Purpose: In order to elucidate anticancer effects of monocarbonyl analogs of curcumin (MACs, we have undertaken the present study to obtain information regarding drug targets by using a microarray approach, and to study the cellular localization of EF24 and the activity of two key transcription factors, AP-1 and NF-κB, involved in complex cellular responses of cell survival and death. Methods: Cytotoxic activity of various drugs was evaluated using a Neutral Red Dye assay. Cellular localization of biotinylated EF24 (active and reduced EF24 (inactive was determined using light and confocal microscopy. Measurement of transcription factor binding was carried out using Transfactor ELISA kits (BD Clontech, Palo Alto, CA. Gene microarray processing was performed at Expression Analysis, Inc (Durham, NC using Affymetrix Human U133A Gene Chips.Results: In this study, we demonstrated that EF24 and UBS109 exhibit much more potent cytotoxic activity against pancreatic cancer than the current standard chemotherapeutic agent gemcitabine. EF24, rapidly localizes to the cell nucleus. The compound modulates the DNA binding activity of NF-κB and AP-1 in MDA-MB-231 human breast cancer cells and DU-145 human prostate cancer cells. Immunohistochemical studies utilizing biotinylated-EF24 and chemically-reduced EF24 show that the unsaturated compound and biotinylated EF24, but not reduced EF24, translocates to the nucleus within 30 minutes after the addition of drug. Through a gene microarray study, EF24 is shown to affect genes directly involved in cytoprotection, tumor growth, angiogenesis, metastasis and apoptosis. Conclusion: EF24 and UBS109 warrant further investigation for development of pancreatic cancer therapy. The dualistic modulations of gene expression may be a manifestation of the cell responses for survival against oxidative stress by EF24. However, the cytotoxic action of EF24 ultimately prevails to kill the cells.

  16. Oxidation states of Fe and Ti in blue sapphire

    International Nuclear Information System (INIS)

    Wongrawang, P; Wongkokua, W; Monarumit, N; Thammajak, N; Wathanakul, P

    2016-01-01

    X-ray absorption near-edge spectroscopy (XANES) can be used to study the oxidation state of a dilute system such as transition metal defects in solid-state samples. In blue sapphire, Fe and Ti are defects that cause the blue color. Inter-valence charge transfer (IVCT) between Fe 2+ and Ti 4+ has been proposed to describe the optical color’s origin. However, the existence of divalent iron cations has not been thoroughly investigated. Fluorescent XANES is therefore employed to study K-edge absorptions of Fe and Ti cations in various blue sapphire samples including natural, synthetic, diffused and heat-treated sapphires. All the samples showed an Fe absorption edge at 7124 eV, corresponding to the Fe 3+ state; and Ti at 4984 eV, corresponding to Ti 4+ . From these results, we propose Fe 3+ -Ti 4+ mixed acceptor states located at 1.75 eV and 2.14 eV above the valence band of corundum, that correspond to 710 nm and 580 nm bands of UV–vis absorption spectra, to describe the cause of the color of blue sapphire. (paper)

  17. Determination of the oxidation states of metals and metalloids: An analytical review

    Science.gov (United States)

    Vodyanitskii, Yu. N.

    2013-12-01

    The hazard of many heavy metals/metalloids in the soil depends on their oxidation state. The problem of determining the oxidation state has been solved due to the use of synchrotron radiation methods with the analysis of the X-ray absorption near-edge structure (XANES). The determination of the oxidation state is of special importance for some hazardous heavy elements (arsenic, antimony, selenium, chromium, uranium, and vanadium). The mobility and hazard of each of these elements depend on its oxidation state. The mobilities are higher at lower oxidation states of As, Cr, V, and Se and at higher oxidation states of Sb and U. The determination of the oxidation state of arsenic has allowed revealing its fixation features in the rhizosphere of hydrophytes. The known oxidation states of chromium and uranium are used for the retention of these elements on geochemical barriers. Different oxidation states have been established for vanadium displacing iron in goethite. The determination of the oxidation state of manganese in the rhizosphere and the photosynthetic apparatus of plants is of special importance for agricultural chemists.

  18. Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

    International Nuclear Information System (INIS)

    Schacht, L.; Navarrete, J.; Schacht, P.; Ramirez, M. A.

    2010-01-01

    V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

  19. Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Schacht, L. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Ciencia de Materiales, Av. IPN s/n, Edificio 9, Col. Lindavista, 07738 Mexico D. F. (Mexico); Navarrete, J.; Schacht, P.; Ramirez, M. A., E-mail: pschacha@imp.m [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D. F. (Mexico)

    2010-07-01

    V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

  20. Manganese oxidation state mediates toxicity in PC12 cells

    International Nuclear Information System (INIS)

    Reaney, S.H.; Smith, D.R.

    2005-01-01

    The role of the manganese (Mn) oxidation state on cellular Mn uptake and toxicity is not well understood. Therefore, undifferentiated PC12 cells were exposed to 0-200 μM Mn(II)-chloride or Mn(III)-pyrophosphate for 24 h, after which cellular manganese levels were measured along with measures of cell viability, function, and cytotoxicity (trypan blue exclusion, medium lactate dehydrogenase (LDH), 8-isoprostanes, cellular ATP, dopamine, serotonin, H-ferritin, transferrin receptor (TfR), Mn-superoxide dismutase (MnSOD), and copper-zinc superoxide dismutase (CuZnSOD) protein levels). Exposures to Mn(III) >10 μM produced 2- to 5-fold higher cellular manganese levels than equimolar exposures to Mn(II). Cell viability and ATP levels both decreased at the highest Mn(II) and Mn(III) exposures (150-200 μM), while Mn(III) exposures produced increases in LDH activity at lower exposures (≥50 μM) than did Mn(II) (200 μM only). Mn(II) reduced cellular dopamine levels more than Mn(III), especially at the highest exposures (50% reduced at 200 μM Mn(II)). In contrast, Mn(III) produced a >70% reduction in cellular serotonin at all exposures compared to Mn(II). Different cellular responses to Mn(II) exposures compared to Mn(III) were also observed for H-ferritin, TfR, and MnSOD protein levels. Notably, these differential effects of Mn(II) versus Mn(III) exposures on cellular toxicity could not simply be accounted for by the different cellular levels of manganese. These results suggest that the oxidation state of manganese exposures plays an important role in mediating manganese cytotoxicity

  1. Measurement of soil carbon oxidation state and oxidative ratio by 13C nuclear magnetic resonance

    Science.gov (United States)

    Hockaday, W.C.; Masiello, C.A.; Randerson, J.T.; Smernik, R.J.; Baldock, J.A.; Chadwick, O.A.; Harden, J.W.

    2009-01-01

    The oxidative ratio (OR) of the net ecosystem carbon balance is the ratio of net O2 and CO2 fluxes resulting from photosynthesis, respiration, decomposition, and other lateral and vertical carbon flows. The OR of the terrestrial biosphere must be well characterized to accurately estimate the terrestrial CO2 sink using atmospheric measurements of changing O2 and CO2 levels. To estimate the OR of the terrestrial biosphere, measurements are needed of changes in the OR of aboveground and belowground carbon pools associated with decadal timescale disturbances (e.g., land use change and fire). The OR of aboveground pools can be measured using conventional approaches including elemental analysis. However, measuring the OR of soil carbon pools is technically challenging, and few soil OR data are available. In this paper we test three solid-state nuclear magnetic resonance (NMR) techniques for measuring soil OR, all based on measurements of the closely related parameter, organic carbon oxidation state (Cox). Two of the three techniques make use of a molecular mixing model which converts NMR spectra into concentrations of a standard suite of biological molecules of known C ox. The third technique assigns Cox values to each peak in the NMR spectrum. We assess error associated with each technique using pure chemical compounds and plant biomass standards whose Cox and OR values can be directly measured by elemental analyses. The most accurate technique, direct polarization solid-state 13C NMR with the molecular mixing model, agrees with elemental analyses to ??0.036 Cox units (??0.009 OR units). Using this technique, we show a large natural variability in soil Cox and OR values. Soil Cox values have a mean of -0.26 and a range from -0.45 to 0.30, corresponding to OR values of 1.08 ?? 0.06 and a range from 0.96 to 1.22. We also estimate the OR of the carbon flux from a boreal forest fire. Analysis of soils from nearby intact soil profiles imply that soil carbon losses associated

  2. The problem of oxidation state stabilisation and some regularities of a Periodic system of the elements

    International Nuclear Information System (INIS)

    Kiselev, Yurii M; Tretyakov, Yuri D

    1999-01-01

    The general principles of the concept of oxidation state stabilisation are formulated. Problems associated with the preparation and provision of the highest valent forms of transition elements are considered. The empirical data concerning the synthesis of new compounds of rare-earth elements and d elements in unusually high oxidation states are analysed. The possibility of occurrence of the oxidation states + 9 and + 10 for some elements (for example, for iridium and platinum in tetraoxo ions) are discussed. Approaches to the realisation of these states are outlined and it is demonstrated that solid phases or matrices containing alkali metal cations are the most promising systems for the stabilisation of these high oxidation states. Selected thermodynamic features typical of metal halides and oxides and the regularities of the changes in the extreme oxidation states of d elements are considered. The bibliography includes 266 references.

  3. Effect of particle size on iron nanoparticle oxidation state

    International Nuclear Information System (INIS)

    Lombardo, Jeffrey J.; Lysaght, Andrew C.; Goberman, Daniel G.; Chiu, Wilson K.S.

    2012-01-01

    Selecting catalyst particles is a very important part of carbon nanotube growth, although the properties of these nanoscale particles are unclear. In this article iron nanoparticles are analyzed through the use of atomic force microscopy and x-ray photoelectron spectroscopy in order to understand how the size affects the chemical composition of nanoparticles and thus their physical structure. Initially, atomic force microscopy was used to confirm the presence of iron particles, and to determine the average size of the particles. Next an analytical model was developed to estimate particle size as a function of deposition time using inputs from atomic force microscopy measurement. X-ray photoelectron spectroscopy analysis was then performed with a focus on the spectra relating to the 2p Fe electrons to study the chemical state of the particles as a function of time. It was shown that as the size of nanoparticles decreased, the oxidation state of the particles changed due to a high proportion of atoms on the surface.

  4. Quantum confinement-induced tunable exciton states in graphene oxide.

    Science.gov (United States)

    Lee, Dongwook; Seo, Jiwon; Zhu, Xi; Lee, Jiyoul; Shin, Hyeon-Jin; Cole, Jacqueline M; Shin, Taeho; Lee, Jaichan; Lee, Hangil; Su, Haibin

    2013-01-01

    Graphene oxide has recently been considered to be a potential replacement for cadmium-based quantum dots due to its expected high fluorescence. Although previously reported, the origin of the luminescence in graphene oxide is still controversial. Here, we report the presence of core/valence excitons in graphene-based materials, a basic ingredient for optical devices, induced by quantum confinement. Electron confinement in the unreacted graphitic regions of graphene oxide was probed by high resolution X-ray absorption near edge structure spectroscopy and first-principles calculations. Using experiments and simulations, we were able to tune the core/valence exciton energy by manipulating the size of graphitic regions through the degree of oxidation. The binding energy of an exciton in highly oxidized graphene oxide is similar to that in organic electroluminescent materials. These results open the possibility of graphene oxide-based optoelectronic device technology.

  5. Study of nuclear reactions and analog isobar states in the system He8 + p for low energy with the help of MAYA active target

    International Nuclear Information System (INIS)

    Demonchy, Ch.E.

    2003-12-01

    With the resent improvements in the field of exotics beams, and specially with the SPIRAL facility at GANIL, we were able to study He 9 shell inversion already known for Be 11 and Li 10 , which are two members of the N=7 family. A new detector was developed and also the software tools for the data analysis. This detector is at the same time the target (active-target) and is called MAYA. The He 9 was studied by determining the properties of its isobaric analogue states in Li 9 . The characteristics of the IAS (isomeric analog state) states were determined by an analysis of the resonances in the elastic scattering cross section for He 8 + p from 2 up to 3.9 MeV/n. A study of (p,d) and (p,t) reactions was done too, in this domain of energy. By comparing the experimental results with calculations, an assignation of spin and parity for two states in He 9 was possible. (author)

  6. Solid state solubility of copper oxides in hydroxyapatite

    Science.gov (United States)

    Zykin, Mikhail A.; Vasiliev, Alexander V.; Trusov, Lev A.; Dinnebier, Robert E.; Jansen, Martin; Kazin, Pavel E.

    2018-06-01

    Samples containing copper oxide doped hydroxyapatite with the composition Ca10(PO4)6(CuxOH1-x-δ)2, x = 0.054 - 0.582, in the mixture with CuO/Cu2O were prepared by a solid-state high-temperature treatment at varying annealing temperatures and at different partial water vapor and oxygen pressures. The crystal structures of the apatite compounds were refined using powder X-ray diffraction patterns and the content of copper ions x in the apatite was determined. Copper ions enter exclusively into the apatite trigonal channels formally substituting protons of OH-groups and the hexagonal cell parameters grow approximately linearly with x, the channel volume mostly expanding while the remaining volume of the crystal lattice changing only slightly. The equilibrium copper content in the apatite increases drastically, by almost a factor of 10 with the annealing temperature rising from 800° to 1200°C. The reduction of the water partial pressure leads to a further increase of x, while the dependence of x on the oxygen partial pressure exhibits a maximum. The observed relations are consistent with the proposed chemical reactions implying the copper introduction is followed by the release of a considerable quantity of gaseous products - water and oxygen. The analysis of interatomic distances suggests that the maximum content of copper ions in the channel cannot exceed 2/3.

  7. Stabilization of actinides and lanthanides in unusually high oxidation states

    International Nuclear Information System (INIS)

    Eller, P.G.; Penneman, R.A.

    1986-01-01

    Chemical environments can be chosen which stabilize actinides and lanthanides in unusually high or low oxidation states and in unusual coordination. In many cases, one can rationalize the observed species as resulting from strong charge/size influences provided by specific sites in host lattices (e.g., Tb(IV) in BaTbO 3 or Am(IV) in polytungstate anions). In other cases, the unusual species can be considered from an acid-base viewpoint (e.g., U(III) in AsF 5 /HF solution or Pu(VII) in Li 5 PuO 6 ). In still other cases, an interplay of steric and redox effects can lead to interesting comparisons (e.g., instability of double fluoride salts of Pu(V) and Pu(VI) relative to U, Np, and Am analogues). Generalized ways to rationalize compounds containing actinides and lanthanides in unusual valences (particularly high valences), including the above and numerous other examples, will form the focus of this paper. Recently developed methods for synthesizing high valent f-element fluorides using superoxidizers and superacids at low temperatures will also be described. 65 refs., 8 figs., 9 tabs

  8. Resistive RAMs as analog trimming elements

    Science.gov (United States)

    Aziza, H.; Perez, A.; Portal, J. M.

    2018-04-01

    This work investigates the use of Resistive Random Access Memory (RRAM) as an analog trimming device. The analog storage feature of the RRAM cell is evaluated and the ability of the RRAM to hold several resistance states is exploited to propose analog trim elements. To modulate the memory cell resistance, a series of short programming pulses are applied across the RRAM cell allowing a fine calibration of the RRAM resistance. The RRAM non volatility feature makes the analog device powers up already calibrated for the system in which the analog trimmed structure is embedded. To validate the concept, a test structure consisting of a voltage reference is evaluated.

  9. Analog filters in nanometer CMOS

    CERN Document Server

    Uhrmann, Heimo; Zimmermann, Horst

    2014-01-01

    Starting from the basics of analog filters and the poor transistor characteristics in nanometer CMOS 10 high-performance analog filters developed by the authors in 120 nm and 65 nm CMOS are described extensively. Among them are gm-C filters, current-mode filters, and active filters for system-on-chip realization for Bluetooth, WCDMA, UWB, DVB-H, and LTE applications. For the active filters several operational amplifier designs are described. The book, furthermore, contains a review of the newest state of research on low-voltage low-power analog filters. To cover the topic of the book comprehensively, linearization issues and measurement methods for the characterization of advanced analog filters are introduced in addition. Numerous elaborate illustrations promote an easy comprehension. This book will be of value to engineers and researchers in industry as well as scientists and Ph.D students at universities. The book is also recommendable to graduate students specializing on nanoelectronics, microelectronics ...

  10. Analog electronics for radiation detection

    CERN Document Server

    2016-01-01

    Analog Electronics for Radiation Detection showcases the latest advances in readout electronics for particle, or radiation, detectors. Featuring chapters written by international experts in their respective fields, this authoritative text: Defines the main design parameters of front-end circuitry developed in microelectronics technologies Explains the basis for the use of complementary metal oxide semiconductor (CMOS) image sensors for the detection of charged particles and other non-consumer applications Delivers an in-depth review of analog-to-digital converters (ADCs), evaluating the pros and cons of ADCs integrated at the pixel, column, and per-chip levels Describes incremental sigma delta ADCs, time-to-digital converter (TDC) architectures, and digital pulse-processing techniques complementary to analog processing Examines the fundamental parameters and front-end types associated with silicon photomultipliers used for single visible-light photon detection Discusses pixel sensors ...

  11. The Behavior of the Ru-bda Water Oxidation Catalysts at Low Oxidation States.

    Science.gov (United States)

    Matheu, Roc; Ghaderian, Abolfazl; Francas, Laia; Chernev, Petko; Ertem, Mehmed; Benet-Buchholz, Jordi; Batista, Victor; Haumann, Michael; Gimbert-Suriñach, Carolina; Sala, Xavier; Llobet, Antoni

    2018-06-13

    The Ru complex [RuII(bda-κ-N2O2)(N-NH2)2], 1, (bda2- = (2,2'-bipyridine)-6,6'-dicarboxylate; N-NH2 = 4-(pyridin-4-yl)aniline) is used as a synthetic intermediate to prepare Ru-bda complexes that contain the NO+, acetonitrile (MeCN) or H2O ligands at oxidation states II and III. Complex 1 reacts with excess NO+ to form a Ru complex where the aryl amine ligands N-NH2 in 1 are transformed into diazonium salts (N-N2+ = 4-(pyridin-4-yl)benzenediazonium)) together with the formation of a new Ru-NO group at the equatorial zone, to generate [RuII(bda-κ-N2O)(NO)(N-N2)2]3+, 23+. Similarly, complex 1 can also react with a coordinating solvent, such as MeCN, at room temperature leading to complex [RuII(bda-κ-N2O)(MeCN)(N-NH2)2], 3. Finally in acidic aqueous solutions solvent water coordinates the Ru center forming {[RuII(bda-κ-(NO)3)(H2O)(N-NH3)2](H2O)n}2+, 42+, that is strongly hydrogen bonded with additional water molecules at the second coordination sphere. We have additionally characterized the one electron oxidized complex {[RuIII(bda-κ-(NO)3.5)(H2O)(N-NH3)2](H2O)n}3+, 53+. The coordination mode of the complexes has been studied both in the solid state and in solution through single-crystal XRD, X-ray absorption spectroscopy, variable-temperature NMR and DFT calculations. While the κ-N2O is the main coordination mode for 23+ and 3, an equilibrium that involves isomers with κ-N2O and κ-NO2 coordination modes and neighboring hydrogen bonded water molecules is observed for 42+ and 53+. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. A microbial-mineralization-inspired approach for synthesis of manganese oxide nanostructures with controlled oxidation states and morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Oba, Manabu; Oaki, Yuya; Imai, Hiroaki [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)

    2010-12-21

    Manganese oxide nanostructures are synthesized by a route inspired by microbial mineralization in nature. The combination of organic molecules, which include antioxidizing and chelating agents, facilitates the parallel control of oxidation states and morphologies in an aqueous solution at room temperature. Divalent manganese hydroxide (Mn(OH){sub 2}) is selectively obtained as a stable dried powder by using a combination of ascorbic acid as an antioxidizing agent and other organic molecules with the ability to chelate to manganese ions. The topotactic oxidation of the resultant Mn(OH){sub 2} leads to the selective formation of trivalent manganese oxyhydroxide ({beta}-MnOOH) and trivalent/tetravalent sodium manganese oxide (birnessite, Na{sub 0.55}Mn{sub 2}O{sub 4}.1.5H{sub 2}O). For microbial mineralization in nature, similar synthetic routes via intermediates have been proposed in earlier works. Therefore, these synthetic routes, which include in the present study the parallel control over oxidation states and morphologies of manganese oxides, can be regarded as new biomimetic routes for synthesis of transition metal oxide nanostructures. As a potential application, it is demonstrated that the resultant {beta}-MnOOH nanostructures perform as a cathode material for lithium ion batteries. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Science Teachers' Analogical Reasoning

    Science.gov (United States)

    Mozzer, Nilmara Braga; Justi, Rosária

    2013-08-01

    Analogies can play a relevant role in students' learning. However, for the effective use of analogies, teachers should not only have a well-prepared repertoire of validated analogies, which could serve as bridges between the students' prior knowledge and the scientific knowledge they desire them to understand, but also know how to introduce analogies in their lessons. Both aspects have been discussed in the literature in the last few decades. However, almost nothing is known about how teachers draw their own analogies for instructional purposes or, in other words, about how they reason analogically when planning and conducting teaching. This is the focus of this paper. Six secondary teachers were individually interviewed; the aim was to characterize how they perform each of the analogical reasoning subprocesses, as well as to identify their views on analogies and their use in science teaching. The results were analyzed by considering elements of both theories about analogical reasoning: the structural mapping proposed by Gentner and the analogical mechanism described by Vosniadou. A comprehensive discussion of our results makes it evident that teachers' content knowledge on scientific topics and on analogies as well as their pedagogical content knowledge on the use of analogies influence all their analogical reasoning subprocesses. Our results also point to the need for improving teachers' knowledge about analogies and their ability to perform analogical reasoning.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1987-06-01

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

  15. Perceptions of Rebuttal Analogy: Politeness and Implications for Persuasion.

    Science.gov (United States)

    Whaley, Bryan B.

    1997-01-01

    States that recent theorizing about the role of analogy in persuasion suggests that "rebuttal" analogy addresses two communicative functions by serving as argument and a method of social attack. Examines message receivers' perceptions of rebuttal analogy and rebuttal analogy users. Finds that participants perceived the communicator using…

  16. Analogical proportions: another logical view

    Science.gov (United States)

    Prade, Henri; Richard, Gilles

    This paper investigates the logical formalization of a restricted form of analogical reasoning based on analogical proportions, i.e. statements of the form a is to b as c is to d. Starting from a naive set theoretic interpretation, we highlight the existence of two noticeable companion proportions: one states that a is to b the converse of what c is to d (reverse analogy), while the other called paralogical proportion expresses that what a and b have in common, c and d have it also. We identify the characteristic postulates of the three types of proportions and examine their consequences from an abstract viewpoint. We further study the properties of the set theoretic interpretation and of the Boolean logic interpretation, and we provide another light on the understanding of the role of permutations in the modeling of the three types of proportions. Finally, we address the use of these proportions as a basis for inference in a propositional setting, and relate it to more general schemes of analogical reasoning. The differences between analogy, reverse-analogy, and paralogy is still emphasized in a three-valued setting, which is also briefly presented.

  17. Intuitive analog circuit design

    CERN Document Server

    Thompson, Marc

    2013-01-01

    Intuitive Analog Circuit Design outlines ways of thinking about analog circuits and systems that let you develop a feel for what a good, working analog circuit design should be. This book reflects author Marc Thompson's 30 years of experience designing analog and power electronics circuits and teaching graduate-level analog circuit design, and is the ideal reference for anyone who needs a straightforward introduction to the subject. In this book, Dr. Thompson describes intuitive and ""back-of-the-envelope"" techniques for designing and analyzing analog circuits, including transistor amplifi

  18. Interface Controlled Oxidation States in Layered Cobalt Oxide Nanoislands on Gold

    DEFF Research Database (Denmark)

    Walton, Alexander; Fester, Jakob; Bajdich, Michal

    2015-01-01

    Layered cobalt oxides have been shown to be highly active catalysts for the oxygen evolution reaction (OER; half of the catalytic “water splitting” reaction), particularly when promoted with gold. However, the surface chemistry of cobalt oxides and in particular the nature of the synergistic effect...

  19. Diversity of Chemical Bonding and Oxidation States in MS 4 Molecules of Group 8 Elements

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Wei [Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084 P.R. China; Jiang, Ning [Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084 P.R. China; Schwarz, W. H. Eugen [Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084 P.R. China; Physical and Theoretical Chemistry, University of Siegen, Siegen 57068 Germany; Yang, Ping [Theoretical Division, Los Alamos National Laboratory, Los Alamos New Mexico 87545 USA; Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland Washington 953002 USA; Li, Jun [Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084 P.R. China; Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland Washington 953002 USA

    2017-07-11

    The geometric and electronic ground-state structures of six MS4 molecules (M = group-8 metals Fe, Ru, Os, Hs, Sm, and Pu) have been studied by using quantum-chemical density-functional and correlated wave-function approaches. The MS4 species are compared to analogous MO4 species recently investi-gated (Inorg. Chem. 2016, 55: 4616). Metal oxidation state (MOS) of high value VIII appears in low- spin singlet Td geometric species (Os,Hs)S4 and (Ru,Os,Hs)O4, whereas low MOS=II appears in high- spin septet D2d species Fe(S2)2 and (slightly excited) metastable Fe(O2)2. The ground states of all other molecules have intermediate MOS values, containing S2-, S22-, S21- (and resp. O2--, O1-, O22-, O21-) ligands, bonded by ionic, covalent and correlative contributions.

  20. Origin of interface states and oxide charges generated by ionizing radiation

    International Nuclear Information System (INIS)

    Sah, C.T.

    1976-01-01

    The randomly located trivalent silicon atoms are shown to account for the thermally generated interface states at the SiO 2 -Si interface. The interface state density is greatly reduced in water containing ambients at low temperatures (450 0 C) by forming trivalent silicon hydroxide bonds. Interface states are regenerated when the /triple bond/Si-OH bonds are broken by ionizing radiation and the OH ions are drifted away. In the bulk of the oxide film, the trivalent silicon and the interstitial oxygen donor centers are shown to be responsible for the heat and radiation generated positive space charge build-up (oxide charge) in thermally grown silicon oxide

  1. Rhetoric and analogies

    OpenAIRE

    Aragonès, Enriqueta; Gilboa, Itzhak; Postlewaite, Andrew; Schmeidler, David; Universitat Autònoma de Barcelona. Unitat de Fonaments de l'Anàlisi Econòmica; Universitat Autònoma de Barcelona. Institut d'Anàlisi Econòmica

    2013-01-01

    The art of rhetoric may be defined as changing other people's minds (opinions, beliefs) without providing them new information. One tech- nique heavily used by rhetoric employs analogies. Using analogies, one may draw the listener's attention to similarities between cases and to re-organize existing information in a way that highlights certain reg- ularities. In this paper we offer two models of analogies, discuss their theoretical equivalence, and show that finding good analogies is a com- p...

  2. Towards a Predictive Thermodynamic Model of Oxidation States of Uranium Incorporated in Fe (hydr) oxides

    Energy Technology Data Exchange (ETDEWEB)

    Bagus, Paul S. [Univ. of North Texas, Denton, TX (United States)

    2013-01-01

    -Level Excited States: Consequences For X-Ray Absorption Spectroscopy”, J. Elec. Spectros. and Related Phenom., 200, 174 (2015) describes our first application of these methods. As well as applications to problems and materials of direct interest for our PNNL colleagues, we have pursued applications of fundamental theoretical significance for the analysis and interpretation of XPS and XAS spectra. These studies are important for the development of the fields of core-level spectroscopies as well as to advance our capabilities for applications of interest to our PNNL colleagues. An excellent example is our study of the surface core-level shifts, SCLS, for the surface and bulk atoms of an oxide that provides a new approach to understanding how the surface electronic of oxides differs from that in the bulk of the material. This work has the potential to lead to a new key to understanding the reactivity of oxide surfaces. Our theoretical studies use cluster models with finite numbers of atoms to describe the properties of condensed phases and crystals. This approach has allowed us to focus on the local atomistic, chemical interactions. For these clusters, we obtain orbitals and spinors through the solution of the Hartree-Fock, HF, and the fully relativistic Dirac HF equations. These orbitals are used to form configuration mixing wavefunctions which treat the many-body effects responsible for the open shell angular momentum coupling and for the satellites of the core-level spectra. Our efforts have been in two complementary directions. As well as the applications described above, we have placed major emphasis on the enhancement and extension of our theoretical and computational capabilities so that we can treat complex systems with a greater range of many-body effects. Noteworthy accomplishments in terms of method development and enhancement have included: (1) An improvement in our treatment of the large matrices that must be handled when many-body effects are treated. (2

  3. Ion bombardment effects on surface states in selected oxide systems: rutile and alkaline earth titanates

    International Nuclear Information System (INIS)

    Gruen, D.M.

    1978-01-01

    In this paper, the nature of the surface states of n-type TiO 2 and SrTiO 3 is discussed and the role of ion bombardment in modifying the properties of these states is elucidated. Insofar as possible, the interrelationships between oxide nonstoichiometry, surface states, ion bombardment effects and photoelectrolysis are explored

  4. Isobaric analog states in rare-earth nuclei studied with the (3He,t) charge-exchange reaction at thetasub(L)=00

    International Nuclear Information System (INIS)

    Jaenecke, J.

    1983-01-01

    The ( 3 He, t) charge-exchange reaction leading to the ground-state isobaric analog states (IAS) of sup(152, 154, 156, 158, 160)Gd, sup(160, 162)Dy, sup(162, 164, 166, 168, 170)Er, sup(170, 172, 174, 176)Yb and sup(176, 178, 180)Hf has been studied at thetasub(L) = 0 0 and E( 3 He) = 60.5 MeV. The reaction 28 Si( 3 He, t) 28 P was used for energy calibration. The centroid energies of most IAS were determined to +- 6 keV. Coulomb displacement energies have been extracted from the measured Q-values. They display the influence of non-spherical nuclear shapes which increase the rms radii and lower the Coulomb displacement energies. The dependence on both quadrupole and hexadecapole deformations is apparent with deformation parameters in good agreement with results from other measurements. The total widths GAMMA of the IAS are in the range 30 to 110 keV. They increase more strongly with neutron excess than is known for the IAS of the Sn and Te isotopes. The width of the IAS of 176 Yb is anomalously low. The zero-degree ( 3 He, t) cross sections are in the range 5 to 20 μb/sr. They generally increase with neutron excess except for the sequence of Yb isotopes. No systematic dependence on (N - Z) appears to exist. Excitation energies and zero-degree cross sections for the reactions 28 Si( 3 He, t) 28 P, 16 O( 3 He, t) 16 F and 12 C( 3 He,t) 12 N are reported. (orig.)

  5. Oxidation Kinetics of Copper: An Experiment in Solid State Chemistry.

    Science.gov (United States)

    Ebisuzaki, Y.; Sanborn, W. B.

    1985-01-01

    Oxidation kinetics in metals and the role defects play in diffusion-controlled reactions are discussed as background for a junior/senior-level experiment in the physical or inorganic chemistry laboratory. Procedures used and typical data obtained are provided for the experiment. (JN)

  6. Analog and hybrid computing

    CERN Document Server

    Hyndman, D E

    2013-01-01

    Analog and Hybrid Computing focuses on the operations of analog and hybrid computers. The book first outlines the history of computing devices that influenced the creation of analog and digital computers. The types of problems to be solved on computers, computing systems, and digital computers are discussed. The text looks at the theory and operation of electronic analog computers, including linear and non-linear computing units and use of analog computers as operational amplifiers. The monograph examines the preparation of problems to be deciphered on computers. Flow diagrams, methods of ampl

  7. Structured Analog CMOS Design

    CERN Document Server

    Stefanovic, Danica

    2008-01-01

    Structured Analog CMOS Design describes a structured analog design approach that makes it possible to simplify complex analog design problems and develop a design strategy that can be used for the design of large number of analog cells. It intentionally avoids treating the analog design as a mathematical problem, developing a design procedure based on the understanding of device physics and approximations that give insight into parameter interdependences. The proposed transistor-level design procedure is based on the EKV modeling approach and relies on the device inversion level as a fundament

  8. Plutonium uptake by Scenedesmus obliquus as a function of isotope and oxidation state

    International Nuclear Information System (INIS)

    Tkacik, M.F.; Giesy, J.P.; Wilhite, E.L.; Corey, J.C.

    1979-01-01

    Uptake of 238 Pu 4+ , 238 Pu 6+ , 239 Pu 4+ and 239 Pu 6+ by the green alga Scenedesmus obliquus (Turp) Kutz was studied to determine whether isotope or oxidation state differences affect Pu uptake from aqueous medium by algal cells. At equivalent 238 Pu and 239 PU concentrations, even when initial oxidation states differed, accumulations of these isotopes by S.obliquus were not significantly (p>0.05) different. Plutonium accumulation by S.obliquus was log-linear. (author)

  9. Generalized molybdenum oxide surface chemical state XPS determination via informed amorphous sample model

    Energy Technology Data Exchange (ETDEWEB)

    Baltrusaitis, Jonas, E-mail: job314@lehigh.edu [Department of Chemical Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States); PhotoCatalytic Synthesis group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Meander 229, P.O. Box 217, 7500 AE Enschede (Netherlands); Mendoza-Sanchez, Beatriz [CRANN, Chemistry School, Trinity College Dublin, Dublin (Ireland); Fernandez, Vincent [Institut des Matériaux Jean Rouxel, 2 rue de la Houssinière, BP 32229, F-44322 Nantes Cedex 3 (France); Veenstra, Rick [PhotoCatalytic Synthesis group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Meander 229, P.O. Box 217, 7500 AE Enschede (Netherlands); Dukstiene, Nijole [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas (Lithuania); Roberts, Adam [Kratos Analytical Ltd, Trafford Wharf Road, Wharfside, Manchester, M17 1GP (United Kingdom); Fairley, Neal [Casa Software Ltd, Bay House, 5 Grosvenor Terrace, Teignmouth, Devon TQ14 8NE (United Kingdom)

    2015-01-30

    Highlights: • We analyzed and modeled spectral envelopes of complex molybdenum oxides. • Molybdenum oxide films of varying valence and crystallinity were synthesized. • MoO{sub 3} and MoO{sub 2} line shapes from experimental data were created. • Informed amorphous sample model (IASM) developed. • Amorphous molybdenum oxide XPS envelopes were interpreted. - Abstract: Accurate elemental oxidation state determination for the outer surface of a complex material is of crucial importance in many science and engineering disciplines, including chemistry, fundamental and applied surface science, catalysis, semiconductors and many others. X-ray photoelectron spectroscopy (XPS) is the primary tool used for this purpose. The spectral data obtained, however, is often very complex and can be subject to incorrect interpretation. Unlike traditional XPS spectra fitting procedures using purely synthetic spectral components, here we develop and present an XPS data processing method based on vector analysis that allows creating XPS spectral components by incorporating key information, obtained experimentally. XPS spectral data, obtained from series of molybdenum oxide samples with varying oxidation states and degree of crystallinity, were processed using this method and the corresponding oxidation states present, as well as their relative distribution was elucidated. It was shown that monitoring the evolution of the chemistry and crystal structure of a molybdenum oxide sample due to an invasive X-ray probe could be used to infer solutions to complex spectral envelopes.

  10. SOLID STATE ENERGY CONVERSION ALLIANCE DELPHI SOLID OXIDE FUEL CELL

    Energy Technology Data Exchange (ETDEWEB)

    Steven Shaffer; Sean Kelly; Subhasish Mukerjee; David Schumann; Gail Geiger; Kevin Keegan; John Noetzel; Larry Chick

    2003-12-08

    The objective of Phase I under this project is to develop a 5 kW Solid Oxide Fuel Cell power system for a range of fuels and applications. During Phase I, the following will be accomplished: Develop and demonstrate technology transfer efforts on a 5 kW stationary distributed power generation system that incorporates steam reforming of natural gas with the option of piped-in water (Demonstration System A). Initiate development of a 5 kW system for later mass-market automotive auxiliary power unit application, which will incorporate Catalytic Partial Oxidation (CPO) reforming of gasoline, with anode exhaust gas injected into an ultra-lean burn internal combustion engine. This technical progress report covers work performed by Delphi from January 1, 2003 to June 30, 2003, under Department of Energy Cooperative Agreement DE-FC-02NT41246. This report highlights technical results of the work performed under the following tasks: Task 1 System Design and Integration; Task 2 Solid Oxide Fuel Cell Stack Developments; Task 3 Reformer Developments; Task 4 Development of Balance of Plant (BOP) Components; Task 5 Manufacturing Development (Privately Funded); Task 6 System Fabrication; Task 7 System Testing; Task 8 Program Management; and Task 9 Stack Testing with Coal-Based Reformate.

  11. Relations as transformations: implications for analogical reasoning.

    Science.gov (United States)

    Leech, Robert; Mareschal, Denis; Cooper, Richard P

    2007-07-01

    We present two experiments assessing whether the size of a transformation instantiating a relation between two states of the world (e.g., shrinks) is a performance factor affecting analogical reasoning. The first experiment finds evidence of transformation size as a significant factor in adolescent analogical problem solving while the second experiment finds a similar effect on adult analogical reasoning using a markedly different analogical completion paradigm. The results are interpreted as providing evidence for the more general framework that cognitive representations of relations are best understood as mental transformations.

  12. Spectrometric analog-to-digital converter

    International Nuclear Information System (INIS)

    Ormandzhiev, S.I.; Jordanov, V.T.

    1988-01-01

    Converter of digit-by-digit counterbalancing with slipping dial with number of channels equal to total number of states of the main digital-to-analog converter of digit-by-digit counterbalancing systems is presented. Algorithm for selection of digital-to-analog converters, which must be used by means of computer is suggested

  13. Folding model study of the charge-exchange scattering to the isobaric analog state and implication for the nuclear symmetry energy

    International Nuclear Information System (INIS)

    Khoa, Dao T.; Thang, Dang Ngoc; Loc, Bui Minh

    2014-01-01

    The Fermi transition (ΔL = ΔS = 0 and ΔT = 1) between the nuclear isobaric analog states (IAS), induced by the charge-exchange (p, n) or ( 3 He, t) reaction, can be considered as ''elastic'' scattering of proton or 3 He by the isovector term of the optical potential (OP) that flips the projectile isospin. The accurately measured (p, n) or ( 3 He, t) scattering cross section to the IAS can be used, therefore, to probe the isospin dependence of the proton or 3 He optical potential. Within the folding model, the isovector part of the OP is determined exclusively by the neutron-proton difference in the nuclear densities and the isospin dependence of the effective nucleon-nucleon (NN) interaction. Because the isovector coupling explicitly links the isovector part of the proton or 3 He optical potential to the cross section of the charge-exchange (p, n) or ( 3 He, t) scattering to the IAS, the isospin dependence of the effective (in-medium) NN interaction can be well tested in the folding model analysis of these charge-exchange reactions. On the other hand, the same isospin- and density-dependent NN interaction can also be used in a Hartree-Fock calculation of asymmetric nuclear matter, to estimate the nuclear matter energy and its asymmetry part (the nuclear symmetry energy). As a result, the fine-tuning of the isospin dependence of the effective NN interaction against the measured (p, n) or ( 3 He, t) cross sections should allow us to make some realistic prediction of the nuclear symmetry energy and its density dependence. (orig.)

  14. Folding model study of the charge-exchange scattering to the isobaric analog state and implication for the nuclear symmetry energy

    Energy Technology Data Exchange (ETDEWEB)

    Khoa, Dao T.; Thang, Dang Ngoc [VINATOM, Institute for Nuclear Science and Technique, Hanoi (Viet Nam); Loc, Bui Minh [VINATOM, Institute for Nuclear Science and Technique, Hanoi (Viet Nam); University of Pedagogy, Ho Chi Minh City (Viet Nam)

    2014-02-15

    The Fermi transition (ΔL = ΔS = 0 and ΔT = 1) between the nuclear isobaric analog states (IAS), induced by the charge-exchange (p, n) or ({sup 3}He, t) reaction, can be considered as ''elastic'' scattering of proton or {sup 3}He by the isovector term of the optical potential (OP) that flips the projectile isospin. The accurately measured (p, n) or ({sup 3}He, t) scattering cross section to the IAS can be used, therefore, to probe the isospin dependence of the proton or {sup 3}He optical potential. Within the folding model, the isovector part of the OP is determined exclusively by the neutron-proton difference in the nuclear densities and the isospin dependence of the effective nucleon-nucleon (NN) interaction. Because the isovector coupling explicitly links the isovector part of the proton or {sup 3}He optical potential to the cross section of the charge-exchange (p, n) or ({sup 3}He, t) scattering to the IAS, the isospin dependence of the effective (in-medium) NN interaction can be well tested in the folding model analysis of these charge-exchange reactions. On the other hand, the same isospin- and density-dependent NN interaction can also be used in a Hartree-Fock calculation of asymmetric nuclear matter, to estimate the nuclear matter energy and its asymmetry part (the nuclear symmetry energy). As a result, the fine-tuning of the isospin dependence of the effective NN interaction against the measured (p, n) or ({sup 3}He, t) cross sections should allow us to make some realistic prediction of the nuclear symmetry energy and its density dependence. (orig.)

  15. Detecting analogies unconsciously

    Directory of Open Access Journals (Sweden)

    Thomas Peter Reber

    2014-01-01

    Full Text Available Analogies may arise from the conscious detection of similarities between a present and a past situation. In this functional magnetic resonance imaging study, we tested whether young volunteers would detect analogies unconsciously between a current supraliminal (visible and a past subliminal (invisible situation. The subliminal encoding of the past situation precludes awareness of analogy detection in the current situation. First, participants encoded subliminal pairs of unrelated words in either one or nine encoding trials. Later, they judged the semantic fit of supraliminally presented new words that either retained a previously encoded semantic relation (‘analog’ or not (‘broken analog’. Words in analogs versus broken analogs were judged closer semantically, which reflects unconscious analogy detection. Hippocampal activity associated with subliminal encoding correlated with the behavioral measure of unconscious analogy detection. Analogs versus broken analogs were processed with reduced prefrontal but enhanced medial temporal activity. We conclude that analogous episodes can be detected even unconsciously drawing on the episodic memory network.

  16. SOLID STATE ENERGY CONVERSION ALLIANCE DELPHI SOLID OXIDE FUEL CELL

    Energy Technology Data Exchange (ETDEWEB)

    Steven Shaffer; Sean Kelly; Subhasish Mukerjee; David Schumann; Gail Geiger; Kevin Keegan; Larry Chick

    2004-05-07

    The objective of this project is to develop a 5 kW Solid Oxide Fuel Cell power system for a range of fuels and applications. During Phase I, the following will be accomplished: Develop and demonstrate technology transfer efforts on a 5 kW stationary distributed power generation system that incorporates steam reforming of natural gas with the option of piped-in water (Demonstration System A). Initiate development of a 5 kW system for later mass-market automotive auxiliary power unit application, which will incorporate Catalytic Partial Oxidation (CPO) reforming of gasoline, with anode exhaust gas injected into an ultra-lean burn internal combustion engine. This technical progress report covers work performed by Delphi from July 1, 2003 to December 31, 2003, under Department of Energy Cooperative Agreement DE-FC-02NT41246. This report highlights technical results of the work performed under the following tasks: Task 1 System Design and Integration; Task 2 Solid Oxide Fuel Cell Stack Developments; Task 3 Reformer Developments; Task 4 Development of Balance of Plant (BOP) Components; Task 5 Manufacturing Development (Privately Funded); Task 6 System Fabrication; Task 7 System Testing; Task 8 Program Management; Task 9 Stack Testing with Coal-Based Reformate; and Task 10 Technology Transfer from SECA CORE Technology Program. In this reporting period, unless otherwise noted Task 6--System Fabrication and Task 7--System Testing will be reported within Task 1 System Design and Integration. Task 8--Program Management, Task 9--Stack Testing with Coal Based Reformate, and Task 10--Technology Transfer from SECA CORE Technology Program will be reported on in the Executive Summary section of this report.

  17. Reduction Rates for Higher Americium Oxidation States in Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Travis Shane [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mincher, Bruce Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schmitt, Nicholas C [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-30

    The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.

  18. The Synthesis and Evaluation of Novel Hydroxyl Substituted Chalcone Analogs with in Vitro Anti-Free Radicals Pharmacological Activity and in Vivo Anti-Oxidation Activity in a Free Radical-Injury Alzheimer’s Model

    Directory of Open Access Journals (Sweden)

    Ying Pan

    2013-01-01

    Full Text Available Alzheimer’s disease (AD pathogenesis involves an imbalance between free radical formation and destruction. In order to obtain a novel preclinical anti-AD drug candidate, we synthesized a series of novel hydroxyl chalcone analogs which possessed anti-free radical activity, and screened their effects on scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH and OH free radicals in vitro. Compound C7, 4,2'-dihydroxy-3,5-dimethoxychalcone was found to have potent activity in these anti-free radical activity tests. Further research revealed that C7 could elevate glutathione peroxidase (GSH-PX and super oxide dismutase (SOD levels and lower malonaldehyde (MDA level in vivo in the Alzheimer’s model. The indication of C7’s effect on AD needs further study.

  19. Analog circuit design

    CERN Document Server

    Dobkin, Bob

    2012-01-01

    Analog circuit and system design today is more essential than ever before. With the growth of digital systems, wireless communications, complex industrial and automotive systems, designers are being challenged to develop sophisticated analog solutions. This comprehensive source book of circuit design solutions aids engineers with elegant and practical design techniques that focus on common analog challenges. The book's in-depth application examples provide insight into circuit design and application solutions that you can apply in today's demanding designs. <

  20. Approaches to Determining the Oxidation State of Nitrogen and Carbon Atoms in Organic Compounds for High School Students

    Science.gov (United States)

    Jurowski, Kamil; Krzeczkowska, Malgorzata Krystyna; Jurowska, Anna

    2015-01-01

    The concept of oxidation state (or oxidation number) and related issues have always been difficult for students. In addition, there are misunderstandings and obscurities, which can cause improper balancing of the chemical equations (mostly in organic reactions). In particular, these problems are related to determination of the oxidation state of…

  1. On matrix stabilisation of d- and f-transition metal ions in unstable oxidation states

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, Yurii M [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2009-01-31

    The state-of-the-art in matrix stabilisation of d- and f-transition metal ions in unstable oxidation states is analysed. Main aspects of this problem concerning the genealogy of appropriate matrix systems are classified. Relevant examples are given and the data that contradict the scheme proposed are discussed. The thermodynamics of the matrix stabilisation effect is considered using the concept of isomorphic miscibility. The influence of defects and non-equilibrium on the matrix stabilisation effect is discussed. The problem of identification of the oxidation states in matrix systems is examined and various types of matrix systems are considered.

  2. On matrix stabilisation of d- and f-transition metal ions in unstable oxidation states

    International Nuclear Information System (INIS)

    Kiselev, Yurii M

    2009-01-01

    The state-of-the-art in matrix stabilisation of d- and f-transition metal ions in unstable oxidation states is analysed. Main aspects of this problem concerning the genealogy of appropriate matrix systems are classified. Relevant examples are given and the data that contradict the scheme proposed are discussed. The thermodynamics of the matrix stabilisation effect is considered using the concept of isomorphic miscibility. The influence of defects and non-equilibrium on the matrix stabilisation effect is discussed. The problem of identification of the oxidation states in matrix systems is examined and various types of matrix systems are considered.

  3. Adsorption properties versus oxidation states of rutile TiO2(110)

    DEFF Research Database (Denmark)

    Martinez, Umberto; Hammer, Bjørk

    2011-01-01

    Using density functional theory we have studied the adsorption properties of different atoms and molecules deposited on a stoichiometric, reduced, and oxidized rutile TiO2(110) surface. Depending on the oxidation state of the surface, electrons can flow from or to the substrate and, therefore...... of the charge flow depends on the oxidation state of the rutile surface and on the adsorption site. Generally, the charging effect leads to more stable complexes. However, the increase in the binding energy of the adsorbates is highly dependent on the electronic states of the surface prior to the adsorption...... event. In this work we have analyzed in details these mechanisms and we have also established a direct correlation between the enhanced binding energy of the adsorbates and the induced gap states...

  4. Analog synthetic biology.

    Science.gov (United States)

    Sarpeshkar, R

    2014-03-28

    We analyse the pros and cons of analog versus digital computation in living cells. Our analysis is based on fundamental laws of noise in gene and protein expression, which set limits on the energy, time, space, molecular count and part-count resources needed to compute at a given level of precision. We conclude that analog computation is significantly more efficient in its use of resources than deterministic digital computation even at relatively high levels of precision in the cell. Based on this analysis, we conclude that synthetic biology must use analog, collective analog, probabilistic and hybrid analog-digital computational approaches; otherwise, even relatively simple synthetic computations in cells such as addition will exceed energy and molecular-count budgets. We present schematics for efficiently representing analog DNA-protein computation in cells. Analog electronic flow in subthreshold transistors and analog molecular flux in chemical reactions obey Boltzmann exponential laws of thermodynamics and are described by astoundingly similar logarithmic electrochemical potentials. Therefore, cytomorphic circuits can help to map circuit designs between electronic and biochemical domains. We review recent work that uses positive-feedback linearization circuits to architect wide-dynamic-range logarithmic analog computation in Escherichia coli using three transcription factors, nearly two orders of magnitude more efficient in parts than prior digital implementations.

  5. Microanalysis of iron oxidation state in iron oxides using X Ray Absorption Near Edge Structure (XANES)

    Science.gov (United States)

    Sutton, S. R.; Delaney, J.; Bajt, S.; Rivers, M. L.; Smith, J. V.

    1993-01-01

    An exploratory application of x ray absorption near edge structure (XANES) analysis using the synchrotron x ray microprobe was undertaken to obtain Fe XANES spectra on individual sub-millimeter grains in conventional polished sections. The experiments concentrated on determinations of Fe valence in a suite of iron oxide minerals for which independent estimates of the iron speciation could be made by electron microprobe analysis and x ray diffraction.

  6. Combating oxidative stress as a hallmark of cancer and aging: Computational modeling and synthesis of phenylene diamine analogs as potential antioxidant

    OpenAIRE

    Abou-zeid, Laila; Baraka, Hany N.

    2014-01-01

    The cross talk between the over expression of oxygen-free radicals is known as reactive oxygen species (ROS) that is associated with the excessive telomerase activity (TA). Telomerase activity is an invariable finding where human telomerase (hTERT) has been implicated in tumor oxidative stress and redox-mediated malignancy. The hTERT over expression is a novel tumor marker and is promising as a novel class of therapeutic weapons to fight against cancer.

  7. Involvement of heme oxygenase-1 expression in neuroprotection by piceatannol, a natural analog and a metabolite of resveratrol, against glutamate-mediated oxidative injury in HT22 neuronal cells.

    Science.gov (United States)

    Son, Yong; Byun, Seung Jae; Pae, Hyun-Ock

    2013-08-01

    Neuronal cell death caused by oxidative stress is common in a variety of neural diseases and can be investigated in detail in cultured HT22 neuronal cells, where the amino acid glutamate at high concentrations causes glutathione depletion by inhibition of the glutamate/cystine antiporter system, intracellular accumulation of reactive oxygen species (ROS) and eventually oxidative stress-induced neuronal cell death. Using this paradigm, we have previously reported that resveratrol (3,5,4'-trans-trihydroxystilbene) protects HT22 neuronal cells from glutamate-induced oxidative stress by inducing heme oxygenase (HO)-1 expression. Piceatannol (3,5,4',3'-trans-trihydroxystilbene), which is a hydroxylated resveratrol analog and one of the resveratrol metabolites, is estimated to exert neuroprotective effect similar to that of resveratrol. The aim of this study, thus, is to determine whether piceatannol, similarly to resveratrol, would protect HT22 neuronal cells from glutamate-induced oxidative stress. Glutamate at high concentrations induced neuronal cell death and ROS formation. Piceatannol reduced glutamate-induced cell death and ROS formation. The observed cytoprotective effect was much higher when HT22 neuronal cells were pretreated with piceatannol for 6 or 12 h prior to glutamate treatment than when pretreated for 0.5 h. Piceatannol also increased HO-1 expression and HO activity via its activation of nuclear factor-E2-related factor 2 (Nrf2). Interestingly, neuroprotective effect of piceatannol was partly (but not completely) abolished by either down-regulation of HO-1 expression or blockage of HO-1 activity. Taken together, our results suggest that piceatannol, similar to resveratrol, is capable of protecting HT22 neuronal cells against glutamate-induced cell death, at least in part, by inducing Nrf2-dependent HO-1 expression.

  8. The oxidation states of elements in pure and Ca-doped BiCuSeO thermoelectric oxides

    International Nuclear Information System (INIS)

    Hsiao, Chun-Lung; Qi, Xiaoding

    2016-01-01

    Bi 1−x Ca x CuSeO (x = 0–0.3) was synthesized at 650 °C in an air-tight system flowing with pure argon. The Ca doping resulted in an increase in the thermoelectric figure of merit (ZT) as the consequence of increased carrier concentration. X-ray photoelectron spectroscopy (XPS) was carried out to check the oxidation states in Bi 1−x Ca x CuSeO. The results indicated that in addition to the expected Bi 3+ and Cu 1+ , there existed Bi 2+ and Cu 2+ in the undoped BiCuSeO, whereas in the Ca-doped BiCuSeO, Bi 4+ , Cu 3+ and Cu 2+ were observed. The Ca dopant was confirmed to be in the 2+ oxidation state. Two broad peaks centered at 54.22 and 58.59 eV were recorded in the vicinity around the binding energy of Se 3d. The former is often observed in the Se-containing intermetallics while the latter is often found in the Se-containing oxides, indicating that along with the expected Se–Cu bonding, a bonding between Se and O may also exist. Based on the XPS results, the charge compensation mechanisms were proposed for Bi 1−x Ca x CuSeO, which may shed some light on the origins of charge carriers. BiCuSeO based oxides have recently be discovered to have a large ZT comparable to the best alloys currently in use, because of the large Seebeck coefficient and small thermal conductivity. However, their electrical conductivity is lower compared to the best thermoelectrics. This work may provide some hints for the further improvement of ZT in BiCuSeO based oxides. - Graphical abstract: The oxidation states, charge compensation mechanisms, and origins of charge carriers in Bi 1−x Ca x CuSeO thermoelectrics. Display Omitted

  9. Ab initio molecular dynamics simulation of aqueous solution of nitric oxide in different formal oxidation states

    Science.gov (United States)

    Venâncio, Mateus F.; Rocha, Willian R.

    2015-10-01

    Ab initio molecular dynamics simulations were used to investigate the early chemical events involved in the dynamics of nitric oxide (NOrad), nitrosonium cation (NO+) and nitroxide anion (NO-) in aqueous solution. The NO+ ion is very reactive in aqueous solution having a lifetime of ∼4 × 10-13 s, which is shorter than the value of 3 × 10-10 s predicted experimentally. The NO+ reacts generating the nitrous acid as an intermediate and the NO2- ion as the final product. The dynamics of NOrad revealed the reversibly formation of a transient anion radical species HONOrad -.

  10. Analog-to-digital conversion

    CERN Document Server

    Pelgrom, Marcel

    2017-01-01

    This textbook is appropriate for use in graduate-level curricula in analog-to-digital conversion, as well as for practicing engineers in need of a state-of-the-art reference on data converters. It discusses various analog-to-digital conversion principles, including sampling, quantization, reference generation, nyquist architectures and sigma-delta modulation. This book presents an overview of the state of the art in this field and focuses on issues of optimizing accuracy and speed, while reducing the power level. This new, third edition emphasizes novel calibration concepts, the specific requirements of new systems, the consequences of 22-nm technology and the need for a more statistical approach to accuracy. Pedagogical enhancements to this edition include additional, new exercises, solved examples to introduce all key, new concepts and warnings, remarks and hints, from a practitioner’s perspective, wherever appropriate. Considerable background information and practical tips, from designing a PCB, to lay-o...

  11. Challenges in Using Analogies

    Science.gov (United States)

    Lin, Shih-Yin; Singh, Chandralekha

    2011-01-01

    Learning physics requires understanding the applicability of fundamental principles in a variety of contexts that share deep features. One way to help students learn physics is via analogical reasoning. Students can be taught to make an analogy between situations that are more familiar or easier to understand and another situation where the same…

  12. Hydraulic Capacitor Analogy

    Science.gov (United States)

    Baser, Mustafa

    2007-01-01

    Students have difficulties in physics because of the abstract nature of concepts and principles. One of the effective methods for overcoming students' difficulties is the use of analogies to visualize abstract concepts to promote conceptual understanding. According to Iding, analogies are consistent with the tenets of constructivist learning…

  13. 99Tc and Re incorporated into metal oxide polyoxometalates: oxidation state stability elucidated by electrochemistry and theory.

    Science.gov (United States)

    McGregor, Donna; Burton-Pye, Benjamin P; Mbomekalle, Israel M; Aparicio, Pablo A; Romo, Susanna; López, Xavier; Poblet, Josep M; Francesconi, Lynn C

    2012-08-20

    The radioactive element technetium-99 ((99)Tc, half-life = 2.1 × 10(5) years, β(-) of 253 keV), is a major byproduct of (235)U fission in the nuclear fuel cycle. (99)Tc is also found in radioactive waste tanks and in the environment at National Lab sites and fuel reprocessing centers. Separation and storage of the long-lived (99)Tc in an appropriate and stable waste-form is an important issue that needs to be addressed. Considering metal oxide solid-state materials as potential storage matrixes for Tc, we are examining the redox speciation of Tc on the molecular level using polyoxometalates (POMs) as models. In this study we investigate the electrochemistry of Tc complexes of the monovacant Wells-Dawson isomers, α(1)-P(2)W(17)O(61)(10-) (α1) and α(2)-P(2)W(17)O(61)(10-) (α2) to identify features of metal oxide materials that can stabilize the immobile Tc(IV) oxidation state accessed from the synthesized Tc(V)O species and to interrogate other possible oxidation states available to Tc within these materials. The experimental results are consistent with density functional theory (DFT) calculations. Electrochemistry of K(7-n)H(n)[Tc(V)O(α(1)-P(2)W(17)O(61))] (Tc(V)O-α1), K(7-n)H(n)[Tc(V)O(α(2)-P(2)W(17)O(61))] (Tc(V)O-α2) and their rhenium analogues as a function of pH show that the Tc-containing derivatives are always more readily reduced than their Re analogues. Both Tc and Re are reduced more readily in the lacunary α1 site as compared to the α2 site. The DFT calculations elucidate that the highest oxidation state attainable for Re is VII while, under the same electrochemistry conditions, the highest oxidation state for Tc is VI. The M(V)→ M(IV) reduction processes for Tc(V)O-α1 are not pH dependent or only slightly pH dependent suggesting that protonation does not accompany reduction of this species unlike the M(V)O-α2 (M = (99)Tc, Re) and Re(V)O-α1 where M(V/IV) reduction process must occur hand in hand with protonation of the terminal M═O to

  14. Optical analogy. Synthesis report

    International Nuclear Information System (INIS)

    1965-01-01

    The authors report the study of conditions under which light attenuation (reflection, diffusion, absorption) and the attenuation of some radiations (notably thermal neutrons) can be described with analogical calculations. The analogy between light physical properties and neutron properties is not searched for, but the analogy between their attenuation characteristics. After having discussed this possible analogy, they propose a mathematical formulation of neutron and optical phenomena which could theoretically justify the optical analogy. The second part reports a more practical study of optics problems such as the study of simple optics materials and illumination measurements, or more precisely the study of angular distributions of optical reflections, a determination of such angular distributions, and an experimental determination of the albedo

  15. Combating oxidative stress as a hallmark of cancer and aging: Computational modeling and synthesis of phenylene diamine analogs as potential antioxidant.

    Science.gov (United States)

    Abou-Zeid, Laila; Baraka, Hany N

    2014-07-01

    The cross talk between the over expression of oxygen-free radicals is known as reactive oxygen species (ROS) that is associated with the excessive telomerase activity (TA). Telomerase activity is an invariable finding where human telomerase (hTERT) has been implicated in tumor oxidative stress and redox-mediated malignancy. The hTERT over expression is a novel tumor marker and is promising as a novel class of therapeutic weapons to fight against cancer. A new series of phenylene diamines were designed, synthesized, and evaluated for their in vitro antioxidant as an indicator of inhibiting the oxidative stress tumor. Compounds 3b and 7b proved to be the most active antioxidants with high percentage ABTS inhibition ranged from 89.40% to 88.59% respectively. Molecular modeling studies indicated that the crest configuration of phenylene diamine nucleus with substitutions of trimethoxy benzamido functional proved to be crucial for enhancing the free radical scavenging activity. Molecular modeling exploration indicated the proper binding selectivity of the 3b and 7b to the 3KYL pocket with promising hTERT inhibitors as a hallmark of cancer.

  16. Carbon oxidation state as a metric for describing the chemistry of atmospheric organic aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Massachusetts Institute of Technology; Kroll, Jesse H.; Donahue, Neil M.; Jimenez, Jose L.; Kessler, Sean H.; Canagaratna, Manjula R.; Wilson, Kevin R.; Altieri, Katye E.; Mazzoleni, Lynn R.; Wozniak, Andrew S.; Bluhm, Hendrik; Mysak, Erin R.; Smith, Jared D.; Kolb, Charles E.; Worsnop, Douglas R.

    2010-11-05

    A detailed understanding of the sources, transformations, and fates of organic species in the environment is crucial because of the central roles that organics play in human health, biogeochemical cycles, and Earth's climate. However, such an understanding is hindered by the immense chemical complexity of environmental mixtures of organics; for example, atmospheric organic aerosol consists of at least thousands of individual compounds, all of which likely evolve chemically over their atmospheric lifetimes. Here we demonstrate the utility of describing organic aerosol (and other complex organic mixtures) in terms of average carbon oxidation state (OSC), a quantity that always increases with oxidation, and is readily measured using state-of-the-art analytical techniques. Field and laboratory measurements of OSC , using several such techniques, constrain the chemical properties of the organics and demonstrate that the formation and evolution of organic aerosol involves simultaneous changes to both carbon oxidation state and carbon number (nC).

  17. Oxidation state analyses of uranium with emphasis on chemical speciation in geological media

    International Nuclear Information System (INIS)

    Ervanne, H.

    2004-01-01

    This thesis focuses on chemical methods suitable for the determination of uranium redox species in geological materials. Nd-coprecipitation method was studied for the determination of uranium oxidation states in ground waters. This method is ideally suited for the separation of uranium oxidation states in the field, which means that problems associated with the instability of U(IV) during transport are avoided. An alternative method, such as ion exchange, is recommended for the analysis of high saline and calcium- and iron-rich ground waters. U(IV)/Utot was 2.8-7.2% in ground waters in oxidizing conditions and 60-93% in anoxic conditions. From thermodynamic model calculations applied to results from anoxic ground waters it was concluded that uranium can act as redox buffer in granitic ground waters. An ion exchange method was developed for the analysis of uranium oxidation states in different solid materials of geological origin. These included uranium minerals, uraniumbearing minerals, fracture coatings and bulk rock. U(IV)/Utot was 50-70% in uraninites, 5.8-8.7% in secondary uranium minerals, 15-49% in different fracture coatings and 64- 77% in samples from deep bedrock. In the uranium-bearing minerals, U(IV)/Utot was 33-43% (allanites), 5.9% (fergusonite) and 93% (monazite). Although the ion exchange method gave reliable results, there is a risk for the conversion of uranium oxidation states during analysis of heterogeneous samples due to the redox reactions that take place in the presence of some iron compounds. This risk was investigated in a study of several common iron-bearing minerals. The risk for conversion of uranium oxidation states can be screened by sample selection and minimized with use of a redox buffer compound such as polyacrylic acid (PAA). In studies of several carboxylic acids, PAA was found to be the most suitable for extending the application of the method. The stability of uranium oxidation states during analysis and the selectivity

  18. Oxidation of extracellular cysteine/cystine redox state in bleomycin-induced lung fibrosis.

    Science.gov (United States)

    Iyer, Smita S; Ramirez, Allan M; Ritzenthaler, Jeffrey D; Torres-Gonzalez, Edilson; Roser-Page, Susanne; Mora, Ana L; Brigham, Kenneth L; Jones, Dean P; Roman, Jesse; Rojas, Mauricio

    2009-01-01

    Several lines of evidence indicate that depletion of glutathione (GSH), a critical thiol antioxidant, is associated with the pathogenesis of idiopathic pulmonary fibrosis (IPF). However, GSH synthesis depends on the amino acid cysteine (Cys), and relatively little is known about the regulation of Cys in fibrosis. Cys and its disulfide, cystine (CySS), constitute the most abundant low-molecular weight thiol/disulfide redox couple in the plasma, and the Cys/CySS redox state (E(h) Cys/CySS) is oxidized in association with age and smoking, known risk factors for IPF. Furthermore, oxidized E(h) Cys/CySS in the culture media of lung fibroblasts stimulates proliferation and expression of transitional matrix components. The present study was undertaken to determine whether bleomycin-induced lung fibrosis is associated with a decrease in Cys and/or an oxidation of the Cys/CySS redox state and to determine whether these changes were associated with changes in E(h) GSH/glutathione disulfide (GSSG). We observed distinct effects on plasma GSH and Cys redox systems during the progression of bleomycin-induced lung injury. Plasma E(h) GSH/GSSG was selectively oxidized during the proinflammatory phase, whereas oxidation of E(h) Cys/CySS occurred at the fibrotic phase. In the epithelial lining fluid, oxidation of E(h) Cys/CySS was due to decreased food intake. Thus the data show that decreased precursor availability and enhanced oxidation of Cys each contribute to the oxidation of extracellular Cys/CySS redox state in bleomycin-induced lung fibrosis.

  19. DetOx: a program for determining anomalous scattering factors of mixed-oxidation-state species.

    Science.gov (United States)

    Sutton, Karim J; Barnett, Sarah A; Christensen, Kirsten E; Nowell, Harriott; Thompson, Amber L; Allan, David R; Cooper, Richard I

    2013-01-01

    Overlapping absorption edges will occur when an element is present in multiple oxidation states within a material. DetOx is a program for partitioning overlapping X-ray absorption spectra into contributions from individual atomic species and computing the dependence of the anomalous scattering factors on X-ray energy. It is demonstrated how these results can be used in combination with X-ray diffraction data to determine the oxidation state of ions at specific sites in a mixed-valance material, GaCl(2).

  20. Studies of surface states in zinc oxide nanopowders

    Science.gov (United States)

    Peters, Raul Mugabe

    The surface of ZnO semiconductor nanosystems is a key performance-defining factor in numerous applications. In this work we present experimental results for the surface defect-related properties of ZnO nanoscale systems. Surface photovoltage spectroscopy was used to determine the defect level energies within the band gap, the conduction vs. valence band nature of the defect-related transitions, and to probe key dynamic parameters of the surface on a number of commercially available ZnO nanopowders. In our experimental setup, surface photovoltage characterization is conducted in high vacuum in tandem with in situ oxygen remote plasma treatments. Surface photovoltage investigations of the as-received and plasma-processed samples revealed a number of common spectral features related to surface states. Furthermore, we observed significant plasma-induced changes in the surface defect properties. Ex situ positron annihilation and photoluminescence measurements were performed on the studied samples and correlated with surface photovoltage results. The average positron lifetimes were found to be substantially longer than in a bulk single crystalline sample, which is consistent with the model of grains with defect-rich surface and subsurface layers. Compression of the powders into pellets yielded reduction of the average positron lifetimes. Surface photovoltage, positron annihilation, and photoluminescence spectra consistently showed sample-to-sample differences due to the variation in the overall quality of the nanopowders, which partially obscures observation of the scaling effects. However, the results demonstrated that our approach is efficient in detecting specific surface states in nanoscale ZnO specimens and in elucidating their nature.

  1. Meat analog: a review.

    Science.gov (United States)

    Malav, O P; Talukder, S; Gokulakrishnan, P; Chand, S

    2015-01-01

    The health-conscious consumers are in search of nutritious and convenient food item which can be best suited in their busy life. The vegetarianism is the key for the search of such food which resembles the meat in respect of nutrition and sensory characters, but not of animal origin and contains vegetable or its modified form, this is the point when meat analog evolved out and gets shape. The consumers gets full satisfaction by consumption of meat analog due to its typical meaty texture, appearance and the flavor which are being imparted during the skilled production of meat analog. The supplement of protein in vegetarian diet through meat alike food can be fulfilled by incorporating protein-rich vegetative food grade materials in meat analog and by adopting proper technological process which can promote the proper fabrication of meat analog with acceptable meat like texture, appearance, flavor, etc. The easily available vegetables, cereals, and pulses in India have great advantages and prospects to be used in food products and it can improve the nutritional and functional characters of the food items. The various form and functional characters of food items are available world over and attracts the meat technologists and the food processors to bring some innovativeness in meat analog and its presentation and marketability so that the acceptability of meat analog can be overgrown by the consumers.

  2. Conformational Toggling of Yeast Iso-1-Cytochrome c in the Oxidized and Reduced States

    Science.gov (United States)

    Yang, Zhongzheng; Zhu, Jing; Ying, Tianlei; Jiang, Xianwang; Zhang, Xu; Wu, Houming; Liu, Maili; Tan, Xiangshi; Cao, Chunyang; Huang, Zhong-Xian

    2011-01-01

    To convert cyt c into a peroxidase-like metalloenzyme, the P71H mutant was designed to introduce a distal histidine. Unexpectedly, its peroxidase activity was found even lower than that of the native, and that the axial ligation of heme iron was changed to His71/His18 in the oxidized state, while to Met80/His18 in the reduced state, characterized by UV-visible, circular dichroism, and resonance Raman spectroscopy. To further probe the functional importance of Pro71 in oxidation state dependent conformational changes occurred in cyt c, the solution structures of P71H mutant in both oxidation states were determined. The structures indicate that the half molecule of cyt c (aa 50–102) presents a kind of “zigzag riveting ruler” structure, residues at certain positions of this region such as Pro71, Lys73 can move a big distance by altering the tertiary structure while maintaining the secondary structures. This finding provides a molecular insight into conformational toggling in different oxidation states of cyt c that is principle significance to its biological functions in electron transfer and apoptosis. Structural analysis also reveals that Pro71 functions as a key hydrophobic patch in the folding of the polypeptide of the region (aa 50–102), to prevent heme pocket from the solvent. PMID:22087268

  3. Troubleshooting analog circuits

    CERN Document Server

    Pease, Robert A

    1991-01-01

    Troubleshooting Analog Circuits is a guidebook for solving product or process related problems in analog circuits. The book also provides advice in selecting equipment, preventing problems, and general tips. The coverage of the book includes the philosophy of troubleshooting; the modes of failure of various components; and preventive measures. The text also deals with the active components of analog circuits, including diodes and rectifiers, optically coupled devices, solar cells, and batteries. The book will be of great use to both students and practitioners of electronics engineering. Other

  4. The Impact of Environmental Factors in Influencing Epigenetics Related to Oxidative States in the Cardiovascular System

    Directory of Open Access Journals (Sweden)

    Francesco Angelini

    2017-01-01

    Full Text Available Oxidative states exert a significant influence on a wide range of biological and molecular processes and functions. When their balance is shifted towards enhanced amounts of free radicals, pathological phenomena can occur, as the generation of reactive oxygen species (ROS in tissue microenvironment or in the systemic circulation can be detrimental. Epidemic chronic diseases of western societies, such as cardiovascular disease, obesity, and diabetes correlate with the imbalance of redox homeostasis. Current advances in our understanding of epigenetics have revealed a parallel scenario showing the influence of oxidative stress as a major regulator of epigenetic gene regulation via modification of DNA methylation, histones, and microRNAs. This has provided both the biological link and a potential molecular explanation between oxidative stress and cardiovascular/metabolic phenomena. Accordingly, in this review, we will provide current insights on the physiological and pathological impact of changes in oxidative states on cardiovascular disorders, by specifically focusing on the influence of epigenetic regulation. A special emphasis will highlight the effect on epigenetic regulation of human’s current life habits, external and environmental factors, including food intake, tobacco, air pollution, and antioxidant-based approaches. Additionally, the strategy to quantify oxidative states in humans in order to determine which biological marker could best match a subject’s profile will be discussed.

  5. Synthesis and anti-inflammatory activity of phenylbutenoid dimer analogs

    International Nuclear Information System (INIS)

    Kim, Sung Soo; Fang, Yuan Ying; Park, Hae Eil

    2015-01-01

    Several phenylbutenoid dimer (PBD) analogs were synthesized and evaluated for their inhibitory activities against nitric oxide (NO) production and TNF-α release. The PBD analogs were synthesized via Diels–Alder and subsequent Schlosser reactions as key steps. Among the tested compounds, two analogs (8c, 8f) exhibited much stronger inhibitory activity against LPS-stimulated NO production and TNF-α release in RAW 264.7 cells than that of wogonin

  6. Mono(pyridine-N-oxide) DOTA analog and its G1/G4-PAMAM dendrimer conjugates labeled with 177Lu: Radiolabeling and biodistribution studies

    International Nuclear Information System (INIS)

    Laznickova, A.; Biricova, V.; Laznicek, M.; Hermann, P.

    2014-01-01

    177 Lu radiolabeling of the first (G1-) or fourth (G4-) generation polyaminoamide (PAMAM) dendrimer conjugates with DOTA-like bifunctional chelator with one methylenepyridine-N-oxide pendant arm (DO3A-py NO-C ) stability of the radiolabeled species and their pharmacokinetic characteristics were evaluated in preclinical experiments. The results showed that the G1- and G4-dendrimer conjugates, modified in average with 7.5 or 57 DO3A-py NO-C chelating units, respectively, can also be labeled with 177 Lu with a high specific activity and radiochemical purity even at 37 °C. The radiolabeled species were stable for at least 24 h. Distribution profile of G1-dendrimer conjugate in organs and tissues of rats was more favorable than that of G4 one. On the other hand, the later dendrimer conjugate bears a substantially higher number of metal chelators per molecule enabling binding of a considerably larger number of radiometals. Our results indicate that an employment of dendrimer-chelate conjugates with bound radiometals might represent a prospective way for radiolabeling of biologically active target-specific macromolecules to obtain markedly high specific activity. - Highlights: • Chelation of DOTA-like ligands suitable for biomacromolecules modification. • Radiolabeling of modified PAMAM-dendrimers with 177 Lu. • Determination of stability of the labeled conjugates. • Pharmacokinetic characteristics evaluated in preclinical experiments

  7. Oxidation states of Fe in LaNi1-xFexO3

    International Nuclear Information System (INIS)

    Goeta, A.E.; Falcon, H.; Carbonio, R.

    1994-01-01

    The distribution of oxidation states in perovskites of the type LaA 1-x B x O 3 (A and B transition metal ions) can be ''tailored'' by x variation. In particular, in LaNiO 3 it has been shown that Fe substitution for Ni foces some Ni 3+ into Ni 2+ , while some Fe 3+ changes into the unusual Fe 4+ state. In addition, the existence of mixed oxidation states of Fe and/or Ni in LaNi 1-x Fe x O 3 has been related to its catalytic activity in hydrogen peroxide decomposition. The Fe 4+ population, obtained using Moessbauer spectroscopy, was found to be constant for all the analyzed annealing temperatures for x = 0.25 concentration, where the isomer shift difference for both states is the highest and the catalytic activity is maximum. (orig.)

  8. Facile solid-state synthesis of oxidation-resistant metal nanoparticles at ambient conditions

    Science.gov (United States)

    Lee, Kyu Hyung; Jung, Hyuk Joon; Lee, Ju Hee; Kim, Kyungtae; Lee, Byeongno; Nam, Dohyun; Kim, Chung Man; Jung, Myung-Hwa; Hur, Nam Hwi

    2018-05-01

    A simple and scalable method for the synthesis of metal nanoparticles in the solid-state was developed, which can produce nanoparticles in the absence of solvents. Nanoparticles of coinage metals were synthesized by grinding solid hydrazine and the metal precursors in their acetates and oxides at 25 °C. The silver and gold acetates converted completely within 6 min into Ag and Au nanoparticles, respectively, while complete conversion of the copper acetate to the Cu sub-micrometer particles took about 2 h. Metal oxide precursors were also converted into metal nanoparticles by grinding alone. The resulting particles exhibit distinctive crystalline lattice fringes, indicating the formation of highly crystalline phases. The Cu sub-micrometer particles are better resistant to oxidation and exhibit higher conductivity compared to conventional Cu nanoparticles. This solid-state method was also applied for the synthesis of platinum group metals and intermetallic Cu3Au, which can be further extended to synthesize other metal nanoparticles.

  9. Advances in Analog Circuit Design 2015

    CERN Document Server

    Baschirotto, Andrea; Harpe, Pieter

    2016-01-01

    This book is based on the 18 tutorials presented during the 24th workshop on Advances in Analog Circuit Design. Expert designers present readers with information about a variety of topics at the frontier of analog circuit design, including low-power and energy-efficient analog electronics, with specific contributions focusing on the design of efficient sensor interfaces and low-power RF systems. This book serves as a valuable reference to the state-of-the-art, for anyone involved in analog circuit research and development. ·         Provides a state-of-the-art reference in analog circuit design, written by experts from industry and academia; ·         Presents material in a tutorial-based format; ·         Includes coverage of high-performance analog-to-digital and digital to analog converters, integrated circuit design in scaled technologies, and time-domain signal processing.

  10. How different oxidation states of crystalline myoglobin are influenced by X-rays.

    Science.gov (United States)

    Hersleth, Hans-Petter; Andersson, K Kristoffer

    2011-06-01

    X-ray induced radiation damage of protein crystals is well known to occur even at cryogenic temperatures. Redox active sites like metal sites seem especially vulnerable for these radiation-induced reductions. It is essential to know correctly the oxidation state of metal sites in protein crystal structures to be able to interpret the structure-function relation. Through previous structural studies, we have tried to characterise and understand the reactions between myoglobin and peroxides. These reaction intermediates are relevant because myoglobin is proposed to take part as scavenger of reactive oxygen species during oxidative stress, and because these intermediates are similar among the haem peroxidases and oxygenases. We have in our previous studies shown that these different myoglobin states are influenced by the X-rays used. In this study, we have in detail investigated the impact that X-rays have on these different oxidation states of myoglobin. An underlying goal has been to find a way to be able to determine mostly unreduced states. We have by using single-crystal light absorption spectroscopy found that the different oxidation states of myoglobin are to a different extent influenced by the X-rays (e.g. ferric Fe(III) myoglobin is faster reduced than ferryl Fe(IV)═O myoglobin). We observe that the higher oxidation states are not reduced to normal ferrous Fe(II) or ferric Fe(III) states, but end up in some intermediate and possibly artificial states. For ferric myoglobin, it seems that annealing of the radiation-induced/reduced state can reversibly more or less give the starting point (ferric myoglobin). Both scavengers and different dose-rates might influence to which extent the different states are affected by the X-rays. Our study shows that it is essential to do a time/dose monitoring of the influence X-rays have on each specific redox-state with spectroscopic techniques like single-crystal light absorption spectroscopy. This will determine to which

  11. Templated electrodeposition of Ag7NO11 nanowires with very high oxidation states of silver

    NARCIS (Netherlands)

    Rodijk, E.J.B.; Maijenburg, A.W.; Maas, M.G.; Blank, David H.A.; ten Elshof, Johan E.

    2011-01-01

    The templated electrodeposition of 200 nm diameter nanowires of the argentic oxynitrate Ag(Ag3O4)2NO3 phase is reported. Their high surface-to-volume ratio and the high average oxidation state of Ag make these wires promising candidates for nanoscale redox processes in which both a high volumetric

  12. Investigation of the oxidation states of Pu isotopes in a hydrochloric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M.H. [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, P. O. Box 105, Yuseong, Daejeon 305-353 (Korea, Republic of)], E-mail: mhlee@kaeri.re.kr; Kim, J.Y.; Kim, W.H.; Jung, E.C.; Jee, K.Y. [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, P. O. Box 105, Yuseong, Daejeon 305-353 (Korea, Republic of)

    2008-12-15

    The characteristics of the oxidation states of Pu in a hydrochloric acid solution were investigated and the results were applied to a separating of Pu isotopes from IAEA reference soils. The oxidation states of Pu(III) and Pu(IV) were prepared by adding hydroxylamine hydrochloride and sodium nitrite to a Pu stock solution, respectively. Also, the oxidation state of Pu(VI) was adjusted with concentrated HNO{sub 3} and HClO{sub 4}. The stability of the various oxidation states of plutonium in a HCl solution with elapsed time after preparation were found to be in the following order: Pu(III){approx}Pu(VI)>Pu(IV)>Pu(V). The chemical recoveries of Pu(IV) in a 9 M HCl solution with an anion exchange resin were similar to those of Pu(VI). This method for the determination of Pu isotopes with an anion exchange resin in a 9 M HCl medium was applied to IAEA reference soils where the activity concentrations of {sup 239,240}Pu and {sup 238}Pu in IAEA-375 and IAEA-326 were consistent with the reference values reported by the IAEA.

  13. Teaching the Properties of Chromium's Oxidation States with a Case Study Method

    Science.gov (United States)

    Ozdilek, Zehra

    2015-01-01

    The purpose of this study was to investigate how a mixed-method case study affects pre-service science teachers' awareness of hexavalent chromium pollution and content knowledge about the properties of chromium's different oxidation states. The study was conducted in Turkey with 55 sophomores during the fall semester of 2013-2014. The students…

  14. The Effect of Precursor Ligands and Oxidation State in the Synthesis of Bimetallic Nano-Alloys

    KAUST Repository

    LaGrow, Alec P.; Knudsen, Kristian; AlYami, Noktan; Anjum, Dalaver H.; Bakr, Osman

    2015-01-01

    of variables on the characteristics of bimetallic nanomaterials are not completely understood. In this study, we used a continuous-flow synthetic strategy to explore the effects of the ligands and the oxidation state of a metal precursor in a shape

  15. Regulation of Ca2+ release from mitochondria by the oxidation-reduction state of pyridine nucleotides

    Science.gov (United States)

    Lehninger, Albert L.; Vercesi, Anibal; Bababunmi, Enitan A.

    1978-01-01

    Mitochondria from normal rat liver and heart, and also Ehrlich tumor cells, respiring on succinate as energy source in the presence of rotenone (to prevent net electron flow to oxygen from the endogenous pyridine nucleotides), rapidly take up Ca2+ and retain it so long as the pyridine nucleotides are kept in the reduced state. When acetoacetate is added to bring the pyridine nucleotides into a more oxidized state, Ca2+ is released to the medium. A subsequent addition of a reductant of the pyridine nucleotides such as β-hydroxybutyrate, glutamate, or isocitrate causes reuptake of the released Ca2+. Successive cycles of Ca2+ release and uptake can be induced by shifting the redox state of the pyridine nucleotides to more oxidized and more reduced states, respectively. Similar observations were made when succinate oxidation was replaced as energy source by ascorbate oxidation or by the hydrolysis of ATP. These and other observations form the basis of a hypothesis for feedback regulation of Ca2+-dependent substrate- or energy-mobilizing enzymatic reactions by the uptake or release of mitochondrial Ca2+, mediated by the cytosolic phosphate potential and the ATP-dependent reduction of mitochondrial pyridine nucleotides by reversal of electron transport. Images PMID:25436

  16. Measurements of the oxidation state and concentration of plutonium in interstitial waters of the Irish Sea

    International Nuclear Information System (INIS)

    Nelson, D.M.; Lovett, M.B.

    1980-01-01

    The question of plutonium movement in interstitial waters resulting from diffusion along concentration gradients or from advective flow is addressed. The results of measurements of both the concentration and the oxidation state of plutonium in interstitial water collected from sediments near the Windscale discharge, in the solid phases of these sediments and in seawater and suspended solids collected at the coring locations are discussed

  17. Analog circuits cookbook

    CERN Document Server

    Hickman, Ian

    2013-01-01

    Analog Circuits Cookbook presents articles about advanced circuit techniques, components and concepts, useful IC for analog signal processing in the audio range, direct digital synthesis, and ingenious video op-amp. The book also includes articles about amplitude measurements on RF signals, linear optical imager, power supplies and devices, and RF circuits and techniques. Professionals and students of electrical engineering will find the book informative and useful.

  18. FGF growth factor analogs

    Science.gov (United States)

    Zamora, Paul O [Gaithersburg, MD; Pena, Louis A [Poquott, NY; Lin, Xinhua [Plainview, NY; Takahashi, Kazuyuki [Germantown, MD

    2012-07-24

    The present invention provides a fibroblast growth factor heparin-binding analog of the formula: ##STR00001## where R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, X, Y and Z are as defined, pharmaceutical compositions, coating compositions and medical devices including the fibroblast growth factor heparin-binding analog of the foregoing formula, and methods and uses thereof.

  19. Effect on days of lactation and methionine hydroxy analog on incorporation of plasma fatty acids into plasma triglycerides

    International Nuclear Information System (INIS)

    Pullen, D.L.; Emergy, R.S.; Palmquist, D.L.

    1989-01-01

    Methionine hydroxy analog has been proposed to stimulate hepatic lipoprotein synthesis and incorporation of plasma fatty acids into plasma triglyceride. Seven cows were fed diets containing 0 to 30 g analog/d starting 14 d prepartum. At approximately 30 and 60 d postpartum, cows were continuously infused intravenously with 1-[ 14 C]palmitic acid for 160 min to achieve steady-state labeling of plasma fatty acid and triglyceride. Turnover of fatty acid and transfer quotients for triglyceride and CO 2 were 3.3 an 2.7 mmol min -1 ; 13.0 and 10.0%; and 8.0 and 5.0%, for control and analog, respectively. Proportion of fatty acid turnover incorporated into triglyceride and CO 2 were 14.0 and 15.0%; and 21.0 and 18.0, respectively, for control and analog. Analog increased 14 C recovered in milk fat (52 vs. 36%). Plasma concentration of fatty acids, percent oxidized to CO 2 , and percent of CO 2 from fatty acids decreased with increasing lactation days. Milk fat percent and yield fatty acid turnover, and oxidation were positively correlated with concentration of plasma fatty acids, whereas fatty acid incorporated into plasma triglyceride was negatively correlated with fatty acid concentration. The data suggest that hepatic triglyceride secretion is not increased in early lactation; further, no effects of analog on lipid metabolism were detected

  20. Heterogeneous Oxidation of Atmospheric Organic Aerosol: Kinetics of Changes to the Amount and Oxidation State of Particle-Phase Organic Carbon.

    Science.gov (United States)

    Kroll, Jesse H; Lim, Christopher Y; Kessler, Sean H; Wilson, Kevin R

    2015-11-05

    Atmospheric oxidation reactions are known to affect the chemical composition of organic aerosol (OA) particles over timescales of several days, but the details of such oxidative aging reactions are poorly understood. In this study we examine the rates and products of a key class of aging reaction, the heterogeneous oxidation of particle-phase organic species by the gas-phase hydroxyl radical (OH). We compile and reanalyze a number of previous studies from our laboratories involving the oxidation of single-component organic particles. All kinetic and product data are described on a common basis, enabling a straightforward comparison among different chemical systems and experimental conditions. Oxidation chemistry is described in terms of changes to key ensemble properties of the OA, rather than to its detailed molecular composition, focusing on two quantities in particular, the amount and the oxidation state of the particle-phase carbon. Heterogeneous oxidation increases the oxidation state of particulate carbon, with the rate of increase determined by the detailed chemical mechanism. At the same time, the amount of particle-phase carbon decreases with oxidation, due to fragmentation (C-C scission) reactions that form small, volatile products that escape to the gas phase. In contrast to the oxidation state increase, the rate of carbon loss is nearly uniform among most systems studied. Extrapolation of these results to atmospheric conditions indicates that heterogeneous oxidation can have a substantial effect on the amount and composition of atmospheric OA over timescales of several days, a prediction that is broadly in line with available measurements of OA evolution over such long timescales. In particular, 3-13% of particle-phase carbon is lost to the gas phase after one week of heterogeneous oxidation. Our results indicate that oxidative aging represents an important sink for particulate organic carbon, and more generally that fragmentation reactions play a major

  1. Influence of microorganisms on the oxidation state distribution of multivalent actinides under anoxic conditions

    International Nuclear Information System (INIS)

    Reed, Donald Timothy; Borkowski, Marian; Lucchini, Jean-Francois; Ams, David; Richmann, M.K.; Khaing, H.; Swanson, J.S.

    2010-01-01

    The fate and potential mobility of multivalent actinides in the subsurface is receiving increased attention as the DOE looks to cleanup the many legacy nuclear waste sites and associated subsurface contamination. Plutonium, uranium and neptunium are the near-surface multivalent contaminants of concern and are also key contaminants for the deep geologic disposal of nuclear waste. Their mobility is highly dependent on their redox distribution at their contamination source as well as along their potential migration pathways. This redox distribution is often controlled, especially in the near-surface where organic/inorganic contaminants often coexist, by the direct and indirect effects of microbial activity. Under anoxic conditions, indirect and direct bioreduction mechanisms exist that promote the prevalence of lower-valent species for multivalent actinides. Oxidation-state-specific biosorption is also an important consideration for long-term migration and can influence oxidation state distribution. Results of ongoing studies to explore and establish the oxidation-state specific interactions of soil bacteria (metal reducers and sulfate reducers) as well as halo-tolerant bacteria and Archaea for uranium, neptunium and plutonium will be presented. Enzymatic reduction is a key process in the bioreduction of plutonium and uranium, but co-enzymatic processes predominate in neptunium systems. Strong sorptive interactions can occur for most actinide oxidation states but are likely a factor in the stabilization of lower-valent species when more than one oxidation state can persist under anaerobic microbiologically-active conditions. These results for microbiologically active systems are interpreted in the context of their overall importance in defining the potential migration of multivalent actinides in the subsurface.

  2. Electrical Circuits and Water Analogies

    Science.gov (United States)

    Smith, Frederick A.; Wilson, Jerry D.

    1974-01-01

    Briefly describes water analogies for electrical circuits and presents plans for the construction of apparatus to demonstrate these analogies. Demonstrations include series circuits, parallel circuits, and capacitors. (GS)

  3. An analog integrated circuit design laboratory

    OpenAIRE

    Mondragon-Torres, A.F.; Mayhugh, Jr.; Pineda de Gyvez, J.; Silva-Martinez, J.; Sanchez-Sinencio, E.

    2003-01-01

    We present the structure of an analog integrated circuit design laboratory to instruct at both, senior undergraduate and entry graduate levels. The teaching material includes: a laboratory manual with analog circuit design theory, pre-laboratory exercises and circuit design specifications; a reference web page with step by step instructions and examples; the use of mathematical tools for automation and analysis; and state of the art CAD design tools in use by industry. Upon completion of the ...

  4. Origin of deep subgap states in amorphous indium gallium zinc oxide: Chemically disordered coordination of oxygen

    International Nuclear Information System (INIS)

    Sallis, S.; Williams, D. S.; Butler, K. T.; Walsh, A.; Quackenbush, N. F.; Junda, M.; Podraza, N. J.; Fischer, D. A.; Woicik, J. C.; White, B. E.; Piper, L. F. J.

    2014-01-01

    The origin of the deep subgap states in amorphous indium gallium zinc oxide (a-IGZO), whether intrinsic to the amorphous structure or not, has serious implications for the development of p-type transparent amorphous oxide semiconductors. We report that the deep subgap feature in a-IGZO originates from local variations in the oxygen coordination and not from oxygen vacancies. This is shown by the positive correlation between oxygen composition and subgap intensity as observed with X-ray photoelectron spectroscopy. We also demonstrate that the subgap feature is not intrinsic to the amorphous phase because the deep subgap feature can be removed by low-temperature annealing in a reducing environment. Atomistic calculations of a-IGZO reveal that the subgap state originates from certain oxygen environments associated with the disorder. Specifically, the subgap states originate from oxygen environments with a lower coordination number and/or a larger metal-oxygen separation.

  5. Origin of deep subgap states in amorphous indium gallium zinc oxide: Chemically disordered coordination of oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Sallis, S.; Williams, D. S. [Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States); Butler, K. T.; Walsh, A. [Center for Sustainable Technologies and Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Quackenbush, N. F. [Department of Physics, Applied Physics, and Astronomy, Binghamton University, Binghamton, New York 13902 (United States); Junda, M.; Podraza, N. J. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States); Fischer, D. A.; Woicik, J. C. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); White, B. E.; Piper, L. F. J., E-mail: lpiper@binghamton.edu [Department of Physics, Applied Physics, and Astronomy, Binghamton University, Binghamton, New York 13902 (United States); Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States)

    2014-06-09

    The origin of the deep subgap states in amorphous indium gallium zinc oxide (a-IGZO), whether intrinsic to the amorphous structure or not, has serious implications for the development of p-type transparent amorphous oxide semiconductors. We report that the deep subgap feature in a-IGZO originates from local variations in the oxygen coordination and not from oxygen vacancies. This is shown by the positive correlation between oxygen composition and subgap intensity as observed with X-ray photoelectron spectroscopy. We also demonstrate that the subgap feature is not intrinsic to the amorphous phase because the deep subgap feature can be removed by low-temperature annealing in a reducing environment. Atomistic calculations of a-IGZO reveal that the subgap state originates from certain oxygen environments associated with the disorder. Specifically, the subgap states originate from oxygen environments with a lower coordination number and/or a larger metal-oxygen separation.

  6. Structural oxidation state studies of the manganese cluster in the oxygen evolving complex of photosystem II

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Wenchuan [Univ. of California, Berkeley, CA (United States)

    1994-11-01

    X-ray absorption spectroscopy (XAS) was performed on Photosystem II (PSII)-enriched membranes prepared from spinach to explore: (1) the correlation between structure and magnetic spin state of the Mn cluster in the oxygen evolving complex (OEC) in the S2 state; and (2) the oxidation state changes of the Mn cluster in the flash-induced S-states. The structure of the Mn cluster in the S2 state with the g~4 electron paramagnetic resonance (EPR) signal (S2-g4 state) was compared with that in the S2 state with multiline signal (S2-MLS state) and the S1 state. The S2-g4 state has a higher XAS inflection point energy than that of the S1 state, indicating the oxidation of Mn in the advance from the S1 to the S2-g4 state. Differences in the edge shape and in the extended X-ray absorption fine structure (EXAFS) show that the structure of the Mn cluster in the S2-g4 state is different from that in the S2-MLS or the S1 state. In the S2-g4 state, the second shell of backscatterers from the Mn absorber contains two Mn-Mn distances of 2.73 Å and 2.85 Å. Very little distance disorder exists in the second shell of the S1 or S2-MLS states. The third shell of the S2-g4 state at about 3.3 Å also contains increased heterogeneity relative to that of the S2-MLS or the S1 state. Various S-states were prepared at room-temperature by saturating, single-turnover flashes. The flash-dependent oscillation in the amplitude of the MLS was used to characterize the S-state composition and to construct "pure" S-state Mn K-edge spectra. The edge position shifts to higher energy by 1.8 eV upon the S1 → S2 transition.

  7. Method of isolation of traces of americium by using the +6 oxidation state properties

    International Nuclear Information System (INIS)

    Kwinta, Jean; Michel, Jean-Jacques

    1969-05-01

    The authors present a method to separate traces of americium from a solution containing fission products and actinides. This method comprises the following steps: firstly, the oxidation of americium at the +6 state by ammonium persulfate and carrying over of actinides and III and IV lanthanides by lanthanum fluoride; secondly, the reduction by hydrazine of the oxidized americium and carrying over of the reduced americium by lutetium fluoride; and thirdly, the americium-lutetium separation by selective extractions either with di 2 ethyl hexyl phosphoric acid, or by fractionated elution on an anionic resin column by a mixture of nitric acid and methanol [fr

  8. Extracellular redox state: refining the definition of oxidative stress in aging.

    Science.gov (United States)

    Jones, Dean P

    2006-01-01

    Oxidative stress in aging can result from an imbalance of prooxidants and antioxidants with excessive, destructive free radical chemistry. Thiol systems are important in the control of these processes, both by protecting against damage and serving in redox signaling mechanisms to sense danger and repair the damage. Studies by a number of research groups in collaboration with the Emory Clinical Biomarkers Laboratory show that the redox state of the central tissue antioxidant, glutathione (GSH), can be measured in human plasma and provides a quantitative systemic indicator of oxidative stress. Plasma GSH/GSSG redox in humans becomes oxidized with age, in response to chemotherapy, as a consequence of cigarette smoking, and in association with common age-related diseases (e.g., type 2 diabetes, cardiovascular disease). However, the GSH/GSSG redox is not equilibrated with the larger plasma cysteine/cystine (Cys/CySS) pool, and the Cys/CySS redox varies with age in a pattern that is distinct from that of GSH/GSSG redox. Furthermore, in vitro studies show that variation in Cys/CySS redox over the range found in vivo affects signaling pathways, which control cell proliferation and oxidant-induced apoptosis. The results point to the conclusion that free radical scavenging antioxidants are of increased importance when thiol/disulfide redox states are oxidized. Because thiol/disulfide redox states, per se, function in redox signaling and control as well as antioxidant protection, GSH/GSSG and Cys/CySS redox states may provide central parameters to link environmental influences and progression of changes associated with aging.

  9. Elucidating the neurotoxic effects of MDMA and its analogs.

    Science.gov (United States)

    Karuppagounder, Senthilkumar S; Bhattacharya, Dwipayan; Ahuja, Manuj; Suppiramaniam, Vishnu; Deruiter, Jack; Clark, Randall; Dhanasekaran, Muralikrishnan

    2014-04-17

    There is a rapid increase in the use of methylenedioxymethamphetamine (MDMA) and its structural congeners/analogs globally. MDMA and MDMA-analogs have been synthesized illegally in furtive dwellings and are abused due to its addictive potential. Furthermore, MDMA and MDMA-analogs have shown to have induced several adverse effects. Hence, understanding the mechanisms mediating this neurotoxic insult of MDMA-analogs is of immense importance for the public health in the world. We synthesized and investigated the neurotoxic effects of MDMA and its analogs [4-methylenedioxyamphetamine (MDA), 2, 6-methylenedioxyamphetamine (MDMA), and N-ethyl-3, 4-methylenedioxyamphetamine (MDEA)]. The stimulatory or the dopaminergic agonist effects of MDMA and MDMA-analogs were elucidated using the established 6-hydroxydopamine lesioned animal model. Additionally, we also investigated the neurotoxic mechanisms of MDMA and MDMA-analogs on mitochondrial complex-I activity and reactive oxygen species generation. MDMA and MDMA-analogs exhibited stimulatory activity as compared to amphetamines and also induced several behavioral changes in the rodents. MDMA and MDMA-analogs enhanced the reactive oxygen generation and inhibited mitochondrial complex-I activity which can lead to neurodegeneration. Hence the mechanism of neurotoxicity, MDMA and MDMA-analogs can enhance the release of monoamines, alter the monoaminergic neurotransmission, and augment oxidative stress and mitochondrial abnormalities leading to neurotoxicity. Thus, our study will help in developing effective pharmacological and therapeutic approaches for the treatment of MDMA and MDMA-analog abuse. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Bridging the Gap: From Model Surfaces to Nanoparticle Analogs for Selective Oxidation and Steam Reforming of Methanol and Selective Hydrogenation Catalysis

    Science.gov (United States)

    Boucher, Matthew B.

    to alkenes was accomplished by the use of state-of-the-art techniques in both surface science and heterogeneous catalysis. The implications of this work can be extended to a wide variety of catalytic systems.

  11. General regularity of the oxidation potential variations and high oxidation states in the second half of the actinide series

    International Nuclear Information System (INIS)

    Spitsyn, V.I.; Vokhmin, V.G.; Ionova, G.V.; Pershina, V.G.

    1984-01-01

    Oxidation potentials (OP) PHI(4/3), PHI(5/3), PHI(6/3), PHI(5/4) and PHI(6/5) are calculated for the members of the actinide series. A semiemperic relation combining OP with explicit terms for ground level energies of actinide ions in Russell-Saunders approximation as well as known values of formal OP relative to the normal hydrogen electrode potential are used as an extrapolation function. It is shown that an increase of PHI(4/3) OP which occurs after Bsub(k) explains a low stability of the oxidation state 4 in solutions for actinides of the second half of the series. PHI(5/3) and PHI(5/4) OP in the section starting with Cm have the minimum at Cf. PHI(6/3) OP for Cm, Bk, Cf and Es are practically the same but for Cm, Bk and Es they are smaller than PHI(5/3) OP. A principle possibility of Bk(6), Cf(6) and Es(6) preparation is shown

  12. In situ oxidation state profiling of nickel hexacyanoferrate derivatized electrodes using line-imaging Raman spectroscopy and multivariate calibration

    International Nuclear Information System (INIS)

    Haight, S.M.; Schwartz, D.T.

    1999-01-01

    Metal hexacyanoferrate compounds show promise as electrochemically switchable ion exchange materials for use in the cleanup of radioactive wastes such as those found in storage basins and underground tanks at the Department of Energy's Hanford Nuclear Reservation. Reported is the use of line-imaging Raman spectroscopy for the in situ determination of oxidation state profiles in nickel hexacyanoferrate derivatized electrodes under potential control in an electrochemical cell. Line-imaging Raman spectroscopy is used to collect 256 contiguous Raman spectra every ∼5 microm from thin films (ca. 80 nm) formed by electrochemical derivatization of nickel electrodes. The cyanide stretching region of the Raman spectrum of the film is shown to be sensitive to iron oxidation state and is modeled by both univariate and multivariate correlations. Although both correlations fit the calibration set well, the multivariate (principle component regression or PCR) model's predictions of oxidation state are less sensitive to noise in the spectrum, yielding a much smoother oxidation state profile than the univariate model. Oxidation state profiles with spatial resolution of approximately 5 microm are shown for a nickel hexacyanoferrate derivatized electrode in reduced, intermediate, and oxidized states. In situ oxidation state profiles indicate that the 647.1 nm laser illumination photo-oxidizes the derivatized electrodes. This observation is confirmed using photoelectrochemical methods

  13. CMOS analog circuit design

    CERN Document Server

    Allen, Phillip E

    1987-01-01

    This text presents the principles and techniques for designing analog circuits to be implemented in a CMOS technology. The level is appropriate for seniors and graduate students familiar with basic electronics, including biasing, modeling, circuit analysis, and some familiarity with frequency response. Students learn the methodology of analog integrated circuit design through a hierarchically-oriented approach to the subject that provides thorough background and practical guidance for designing CMOS analog circuits, including modeling, simulation, and testing. The authors' vast industrial experience and knowledge is reflected in the circuits, techniques, and principles presented. They even identify the many common pitfalls that lie in the path of the beginning designer--expert advice from veteran designers. The text mixes the academic and practical viewpoints in a treatment that is neither superficial nor overly detailed, providing the perfect balance.

  14. Coupled interactions between volatile activity and Fe oxidation state during arc crustal processes

    Science.gov (United States)

    Humphreys, Madeleine C.S.; Brooker, R; Fraser, D.C.; Burgisser, A; Mangan, Margaret T.; McCammon, C

    2015-01-01

    Arc magmas erupted at the Earth’s surface are commonly more oxidized than those produced at mid-ocean ridges. Possible explanations for this high oxidation state are that the transfer of fluids during the subduction process results in direct oxidation of the sub-arc mantle wedge, or that oxidation is caused by the effect of later crustal processes, including protracted fractionation and degassing of volatile-rich magmas. This study sets out to investigate the effect of disequilibrium crustal processes that may involve coupled changes in H2O content and Fe oxidation state, by examining the degassing and hydration of sulphur-free rhyolites. We show that experimentally hydrated melts record strong increases in Fe3+/∑Fe with increasing H2O concentration as a result of changes in water activity. This is relevant for the passage of H2O-undersaturated melts from the deep crust towards shallow crustal storage regions, and raises the possibility that vertical variations in fO2 might develop within arc crust. Conversely, degassing experiments produce an increase in Fe3+/∑Fe with decreasing H2O concentration. In this case the oxidation is explained by loss of H2 as well as H2O into bubbles during decompression, consistent with thermodynamic modelling, and is relevant for magmas undergoing shallow degassing en route to the surface. We discuss these results in the context of the possible controls on fO2 during the generation, storage and ascent of magmas in arc settings, in particular considering the timescales of equilibration relative to observation as this affects the quality of the petrological record of magmatic fO2.

  15. Susceptibility of β1 Na+-K+ pump subunit to glutathionylation and oxidative inhibition depends on conformational state of pump.

    Science.gov (United States)

    Liu, Chia-Chi; Garcia, Alvaro; Mahmmoud, Yasser A; Hamilton, Elisha J; Galougahi, Keyvan Karimi; Fry, Natasha A S; Figtree, Gemma A; Cornelius, Flemming; Clarke, Ronald J; Rasmussen, Helge H

    2012-04-06

    Glutathionylation of cysteine 46 of the β1 subunit of the Na(+)-K(+) pump causes pump inhibition. However, the crystal structure, known in a state analogous to an E2·2K(+)·P(i) configuration, indicates that the side chain of cysteine 46 is exposed to the lipid bulk phase of the membrane and not expected to be accessible to the cytosolic glutathione. We have examined whether glutathionylation depends on the conformational changes in the Na(+)-K(+) pump cycle as described by the Albers-Post scheme. We measured β1 subunit glutathionylation and function of Na(+)-K(+)-ATPase in membrane fragments and in ventricular myocytes. Signals for glutathionylation in Na(+)-K(+)-ATPase-enriched membrane fragments suspended in solutions that preferentially induce E1ATP and E1Na(3) conformations were much larger than signals in solutions that induce the E2 conformation. Ouabain further reduced glutathionylation in E2 and eliminated an increase seen with exposure to the oxidant peroxynitrite (ONOO(-)). Inhibition of Na(+)-K(+)-ATPase activity after exposure to ONOO(-) was greater when the enzyme had been in the E1Na(3) than the E2 conformation. We exposed myocytes to different extracellular K(+) concentrations to vary the membrane potential and hence voltage-dependent conformational poise. K(+) concentrations expected to shift the poise toward E2 species reduced glutathionylation, and ouabain eliminated a ONOO(-)-induced increase. Angiotensin II-induced NADPH oxidase-dependent Na(+)-K(+) pump inhibition was eliminated by conditions expected to shift the poise toward the E2 species. We conclude that susceptibility of the β1 subunit to glutathionylation depends on the conformational poise of the Na(+)-K(+) pump.

  16. Susceptibility of β1 Na+-K+ Pump Subunit to Glutathionylation and Oxidative Inhibition Depends on Conformational State of Pump*

    Science.gov (United States)

    Liu, Chia-Chi; Garcia, Alvaro; Mahmmoud, Yasser A.; Hamilton, Elisha J.; Galougahi, Keyvan Karimi; Fry, Natasha A. S.; Figtree, Gemma A.; Cornelius, Flemming; Clarke, Ronald J.; Rasmussen, Helge H.

    2012-01-01

    Glutathionylation of cysteine 46 of the β1 subunit of the Na+-K+ pump causes pump inhibition. However, the crystal structure, known in a state analogous to an E2·2K+·Pi configuration, indicates that the side chain of cysteine 46 is exposed to the lipid bulk phase of the membrane and not expected to be accessible to the cytosolic glutathione. We have examined whether glutathionylation depends on the conformational changes in the Na+-K+ pump cycle as described by the Albers-Post scheme. We measured β1 subunit glutathionylation and function of Na+-K+-ATPase in membrane fragments and in ventricular myocytes. Signals for glutathionylation in Na+-K+-ATPase-enriched membrane fragments suspended in solutions that preferentially induce E1ATP and E1Na3 conformations were much larger than signals in solutions that induce the E2 conformation. Ouabain further reduced glutathionylation in E2 and eliminated an increase seen with exposure to the oxidant peroxynitrite (ONOO−). Inhibition of Na+-K+-ATPase activity after exposure to ONOO− was greater when the enzyme had been in the E1Na3 than the E2 conformation. We exposed myocytes to different extracellular K+ concentrations to vary the membrane potential and hence voltage-dependent conformational poise. K+ concentrations expected to shift the poise toward E2 species reduced glutathionylation, and ouabain eliminated a ONOO−-induced increase. Angiotensin II-induced NADPH oxidase-dependent Na+-K+ pump inhibition was eliminated by conditions expected to shift the poise toward the E2 species. We conclude that susceptibility of the β1 subunit to glutathionylation depends on the conformational poise of the Na+-K+ pump. PMID:22354969

  17. Analogical Reasoning in Geometry Education

    Science.gov (United States)

    Magdas, Ioana

    2015-01-01

    The analogical reasoning isn't used only in mathematics but also in everyday life. In this article we approach the analogical reasoning in Geometry Education. The novelty of this article is a classification of geometrical analogies by reasoning type and their exemplification. Our classification includes: analogies for understanding and setting a…

  18. Digital and analog communication systems

    Science.gov (United States)

    Shanmugam, K. S.

    1979-01-01

    The book presents an introductory treatment of digital and analog communication systems with emphasis on digital systems. Attention is given to the following topics: systems and signal analysis, random signal theory, information and channel capacity, baseband data transmission, analog signal transmission, noise in analog communication systems, digital carrier modulation schemes, error control coding, and the digital transmission of analog signals.

  19. Analogs for transuranic elements

    International Nuclear Information System (INIS)

    Weimer, W.C.; Laul, J.C.; Kutt, J.C.

    1981-01-01

    A combined theoretical and experimental approach is being used to estimate the long-term environmental and biogeochemical behaviors of selected transuranic elements. The objective of this research is to estimate the effect that long-term (hundreds of years) environmental weathering has on the behavior of the transuranic elements americium and curium. This is achieved by investigating the actual behavior of naturally occurring rare earth elements, especially neodymium, that serve as transuranic analogs. Determination of the analog element behavior provides data that can be used to estimate the ultimate availability to man of transuranic materials released into the environment

  20. Radiation oxidation of polypropylene: A solid-state 13C NMR study using selective isotopic labeling

    International Nuclear Information System (INIS)

    Mowery, Daniel M.; Assink, Roger A.; Derzon, Dora K.; Klamo, Sara B.; Bernstein, Robert; Clough, Roger L.

    2007-01-01

    Polypropylene samples, in which the three different carbon atoms along the chain were selectively labeled with carbon-13, were subjected to radiation under inert and air atmospheres, and to post-irradiation exposure in air at various temperatures. By using solid-state 13 C NMR measurements at room temperature, we have been able to identify and quantify the oxidation products. The isotopic labeling provides insight into chemical reaction mechanisms, since oxidation products can be traced back to their positions of origin on the macromolecule. The major products include peroxides and alcohols, both formed at tertiary carbon sites along the chain. Other products include methyl ketones, acids, esters, peresters, and hemiketals formed from reaction at the tertiary carbon, together with in-chain ketones and esters from reaction at the secondary chain carbon. No evidence is found of products arising from reactions at the methyl side chain. Significant temperature-dependent differences are apparent; for example much higher yields of chain-end methyl ketones, which are the indicator product of chain scission, are generated for both elevated temperature irradiation and for post-irradiation treatment at elevated temperatures. Time-dependent plots of yields of the various oxidation products have been obtained under a wide range of conditions, including the post-irradiation oxidation of a sample at room temperature in air that has been monitored for 2 years. Radiation-oxidation products of polypropylene are contrasted to products measured for 13 C-labeled polyethylene in an earlier investigation: the peroxides formed in irradiated polypropylene are remarkably longer lived, the non-peroxidic products are significantly different, and the overall ratios of oxidation products in polypropylene change relatively little as a function of the extent of oxidation

  1. Microbial utilization of low molecular weight organic substrates in soil depends on their carbon oxidation state

    Science.gov (United States)

    Gunina, Anna; Smith, Andrew; Jones, Davey; Kuzyakov, Yakov

    2017-04-01

    Removal of low molecular weight organic substances (LMWOS), originating from plants and microorganisms, from soil solution is regulated by microbial uptake. In addition to the concentration of LMWOS in soil solution, the chemical properties of each substance (e.g. C oxidation state, number of C atoms, number of -COOH groups) can affect their uptake and subsequent partitioning of C within the soil microbial community. The aim of this study was to trace the initial fate of three dominant classes of LMWOS in soil (sugars, carboxylic and amino acids), including their removal from solution and utilization by microorganisms, and to reveal the effect of substance chemical properties on these processes. Soil solution, spiked at natural abundance levels with 14C-labelled glucose, fructose, malate, succinate, formate, alanine or glycine, was added to the soil and 14C was traced in the dissolved organic carbon (DOC), CO2, cytosol and soil organic carbon (SOC) over 24 hours. The half-life time of all LMWOS in the DOC (T1 /2-solution) varied between 0.6-5.0 min showing extremely fast initial uptake of LMWOS. The T1 /2-solution of substances was dependent on C oxidation state, indicating that less oxidized organic substances (with C oxidation state "0") were retained longer in soil solution than oxidized substances. The LMWOS-C T1 /2-fast, characterizing the half-life time of 14C in the fast mineralization pool, ranged between 30 and 80 min, with the T1 /2-fast of carboxylic acids (malic acid) being the fastest and the T1 /2-fast of amino acids (glycine) being the slowest. An absence of correlation between T1 /2-fast and either C oxidation state, number of C atoms, or number of -COOH groups suggests that intercellular metabolic pathways are more important for LMWOS transformation in soil than their basic chemical properties. The CO2 release during LMWOS mineralization accounted for 20-90% of 14C applied. Mineralization of LMWOS was the least for sugars and the greatest for

  2. Influence of steam generator surface state on corrosion and oxide formation

    International Nuclear Information System (INIS)

    Mazenc, Arnaud; Leclercq, Stephanie; Seyeux, Antoine; Galtayries, Anouk; Marcus, Philippe

    2012-09-01

    The corrosion and release of nickel-based alloy Steam Generator tubes are partly due to their surface state. Among the most important parameters influencing the corrosion, the effect of grain size and the effect of grain crystallographic orientation have been chosen to be studied. The aim of this study is to determine how these parameters have an impact on the corrosion of Steam Generator tubes. Thermal treatments (700 deg. C and 1050 deg. C) have been performed on several samples in Alloy 690 to obtain homogeneous grain sizes, varying from 25 μm to 110 μm. Two samples have been oxidised for four days in a recirculating autoclave, reproducing primary conditions. The changes of oxide composition and thickness were examined by ToF-SIMS on samples exposed to primary water conditions. The intensity profiles versus thicknesses of characteristic oxide anions, such as CrO - , NiO - or FeO - enable us to evaluate the effect of grain size and crystallographic orientation on the formation of an enriched inner chromium layer. As regards to the grain size, there was no effect on the growth, but smaller grains led to a chromium-rich oxide layer. The effect of crystallographic orientation was observed on the oxidation kinetics and the composition of oxide scales. (authors)

  3. Characterization of Interface State in Silicon Carbide Metal Oxide Semiconductor Capacitors

    Science.gov (United States)

    Kao, Wei-Chieh

    Silicon carbide (SiC) has always been considered as an excellent material for high temperature and high power devices. Since SiC is the only compound semiconductor whose native oxide is silicon dioxide (SiO2), it puts SiC in a unique position. Although SiC metal oxide semiconductor (MOS) technology has made significant progress in recent years, there are still a number of issues to be overcome before more commercial SiC devices can enter the market. The prevailing issues surrounding SiC MOSFET devices are the low channel mobility, the low quality of the oxide layer and the high interface state density at the SiC/SiO2 interface. Consequently, there is a need for research to be performed in order to have a better understanding of the factors causing the poor SiC/SiO2 interface properties. In this work, we investigated the generation lifetime in SiC materials by using the pulsed metal oxide semiconductor (MOS) capacitor method and measured the interface state density distribution at the SiC/SiO2 interface by using the conductance measurement and the high-low frequency capacitance technique. These measurement techniques have been performed on n-type and p-type SiC MOS capacitors. In the course of our investigation, we observed fast interface states at semiconductor-dielectric interfaces in SiC MOS capacitors that underwent three different interface passivation processes, such states were detected in the nitrided samples but not observed in PSG-passivated samples. This result indicate that the lack of fast states at PSG-passivated interface is one of the main reasons for higher channel mobility in PSG MOSFETs. In addition, the effect of mobile ions in the oxide on the response time of interface states has been investigated. In the last chapter we propose additional methods of investigation that can help elucidate the origin of the particular interface states, enabling a more complete understanding of the SiC/SiO2 material system.

  4. A magnetic route to measure the average oxidation state of mixed-valent manganese in manganese oxide octahedral molecular sieves (OMS).

    Science.gov (United States)

    Shen, Xiong-Fei; Ding, Yun-Shuang; Liu, Jia; Han, Zhao-Hui; Budnick, Joseph I; Hines, William A; Suib, Steven L

    2005-05-04

    A magnetic route has been applied for measurement of the average oxidation state (AOS) of mixed-valent manganese in manganese oxide octahedral molecular sieves (OMS). The method gives AOS measurement results in good agreement with titration methods. A maximum analysis deviation error of +/-7% is obtained from 10 sample measurements. The magnetic method is able to (1) confirm the presence of mixed-valent manganese and (2) evaluate AOS and the spin states of d electrons of both single oxidation state and mixed-valent state Mn in manganese oxides. In addition, the magnetic method may be extended to (1) determine AOS of Mn in manganese oxide OMS with dopant "diamagnetic" ions, such as reducible V5+ (3d0) ions, which is inappropriate for the titration method due to interference of redox reactions between these dopant ions and titration reagents, such as KMnO4, (2) evaluate the dopant "paramagnetic" ions that are present as clusters or in the OMS framework, and (3) determine AOS of other mixed-valent/single oxidation state ion systems, such as Mo3+(3d3)-Mo4+(3d2) systems and Fe3+ in FeCl3.

  5. Solid state chemistry of rare earth oxides. Final report, September 1, 1950--July 31, 1977

    International Nuclear Information System (INIS)

    Eyring, L.

    1977-07-01

    Work under Contract E(11-1)-1109 and its antecedents has been primarily for the purpose of obtaining detailed thermodynamic, kinetic and structural information on the complex rare earth oxides of praseodymium and terbium. These systems exhibit homologous series of ordered phases, order-disorder transformations, wide-range nonstoichiometric phases, chemical hysteresis in two-phase regions and many other solid state reaction phenomena. Fluorite-related materials of importance to ERDA occur as nuclear fuels, radiation power sources, insulators and solid electrolytes. The rare earth oxides serve directly as model systems for such similar materials and, in a more general sense, they serve as models of solids in general since they exhibit nearly the full range of solid state properties

  6. Solid State Electrochemical Sensors for Nitrogen Oxide (NOx) Detection in Lean Exhaust Gases

    OpenAIRE

    Rheaume, Jonathan Michael

    2010-01-01

    Solid state electrochemical sensors that measure nitrogen oxides (NOx) in lean exhaust have been investigated in order to help meet future on-board diagnostic (OBD) regulations for diesel vehicles. This impedancemetric detection technology consists of a planar, single cell sensor design with various sensing electrode materials and yttria-stabilized zirconia (YSZ) as the electrolyte. No reference to ambient air is required. An impedance analysis method yields a signal that is proportional to t...

  7. Natural Analog Studies at Pena Blanca, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    A.M. Simmons

    2005-07-11

    The significance of the Pena Blanca uranium deposits in the State of Chihuahua, Mexico as potential natural analogs for a nuclear waste repository in unsaturated welded tuff was first recognized in the 1980s. In the 1970s, the Pena Blanca region was a major target of uranium exploration and exploitation by the Mexican government. Since then the Nopal I uranium deposit has been studied extensively by researchers in the U.S., Mexico, and Europe. The Nopal I deposit represents an environment similar to that of the proposed high-level radioactive waste repository at Yucca Mountain in many ways. Both are located in semi-arid regions. Both are located in Tertiary rhyolitic tuffs overlying carbonate rocks that have been subjected to basin and range-style tectonic deformation. Both are located in a chemically oxidizing, unsaturated zone 200 m or more above the water table. The alteration of uraninite to secondary minerals at Nopal I may be similar to the alteration of uranium fuel rods in this type of setting. Investigations at Nopal I and in the surrounding Sierra Pena Blanca have included detailed outcrop mapping, hydrologic and isotopic studies of flow and transport, studies of mineral alteration, modeling, and performance assessment.

  8. Natural Analog Studies at Pena Blanca, Mexico

    International Nuclear Information System (INIS)

    A.M. Simmons

    2005-01-01

    The significance of the Pena Blanca uranium deposits in the State of Chihuahua, Mexico as potential natural analogs for a nuclear waste repository in unsaturated welded tuff was first recognized in the 1980s. In the 1970s, the Pena Blanca region was a major target of uranium exploration and exploitation by the Mexican government. Since then the Nopal I uranium deposit has been studied extensively by researchers in the U.S., Mexico, and Europe. The Nopal I deposit represents an environment similar to that of the proposed high-level radioactive waste repository at Yucca Mountain in many ways. Both are located in semi-arid regions. Both are located in Tertiary rhyolitic tuffs overlying carbonate rocks that have been subjected to basin and range-style tectonic deformation. Both are located in a chemically oxidizing, unsaturated zone 200 m or more above the water table. The alteration of uraninite to secondary minerals at Nopal I may be similar to the alteration of uranium fuel rods in this type of setting. Investigations at Nopal I and in the surrounding Sierra Pena Blanca have included detailed outcrop mapping, hydrologic and isotopic studies of flow and transport, studies of mineral alteration, modeling, and performance assessment

  9. Quantitative evaluation of the effect of H2O degassing on the oxidation state of magmas

    Science.gov (United States)

    Lange, R. A.; Waters, L.

    2014-12-01

    The extent to which degassing of the H2O component affects the oxidation state of hydrous magmas is widely debated. Several researchers have examined how degassing of mixed H-C-O-S-Cl fluids may change the Fe3+/FeT ratio of various magmas, whereas our focus is on the H2O component. There are two ways that degassing of H2O by itself may cause oxidation: (1) the reaction: H2O (melt) + 2FeO (melt) = H2 (fluid) + Fe2O3 (melt), and/or (2) if dissolved water preferentially enhances the activity of ferrous vs. ferric iron in magmatic liquids. In this study, a comparison is made between the pre-eruptive oxidation states of 14 crystal-poor, jet-black obsidian samples (obtained from two Fe-Ti oxides) and their post-eruptive values (analyzed with the Wilson 1960 titration method tested against USGS standards). The obsidians are from Medicine Lake (CA), Long Valley (CA), and the western Mexican arc; all have low FeOT (1.1-2.1 wt%), rendering their Fe2+/Fe3+ ratios highly sensitive to the possible effects of substantial H2O degassing. The Fe-Ti oxide thermometer/oxybarometer of Ghiorso and Evans, (2008) gave temperatures for the 14 samples that range for 720 to 940°C and ΔNNO values of -0.9 to +1.4. With temperature known, the plagioclase-liquid hygrometer was applied and show that ≤ 6.5 wt% H2O was dissolved in the melts prior to eruption. In addition, pre-eruptive Cl and S concentrations were constrained on the basis of apatite analyses (Webster et al., 2009) and sulfur concentrations needed for saturation with pyrrhotite (Clemente et al., 2004), respectively. Maximum pre-eruptive chlorine and sulfur contents are 6000 and 200 ppm, respectively. After eruption, the rhyolites lost nearly all of their volatiles. Our results indicate no detectable change between pre- and post-eruptive Fe2+ concentrations, with an average deviation of ± 0.1 wt % FeO. Although degassing of large concentrations of S and/or Cl may affect the oxidation state of magmas, at the pre-eruptive levels

  10. Terrestrial Analogs to Mars

    Science.gov (United States)

    Farr, T. G.; Arcone, S.; Arvidson, R. W.; Baker, V.; Barlow, N. G.; Beaty, D.; Bell, M. S.; Blankenship, D. D.; Bridges, N.; Briggs, G.; Bulmer, M.; Carsey, F.; Clifford, S. M.; Craddock, R. A.; Dickerson, P. W.; Duxbury, N.; Galford, G. L.; Garvin, J.; Grant, J.; Green, J. R.; Gregg, T. K. P.; Guinness, E.; Hansen, V. L.; Hecht, M. H.; Holt, J.; Howard, A.; Keszthelyi, L. P.; Lee, P.; Lanagan, P. D.; Lentz, R. C. F.; Leverington, D. W.; Marinangeli, L.; Moersch, J. E.; Morris-Smith, P. A.; Mouginis-Mark, P.; Olhoeft, G. R.; Ori, G. G.; Paillou, P.; Reilly, J. F., II; Rice, J. W., Jr.; Robinson, C. A.; Sheridan, M.; Snook, K.; Thomson, B. J.; Watson, K.; Williams, K.; Yoshikawa, K.

    2002-08-01

    It is well recognized that interpretations of Mars must begin with the Earth as a reference. The most successful comparisons have focused on understanding geologic processes on the Earth well enough to extrapolate to Mars' environment. Several facets of terrestrial analog studies have been pursued and are continuing. These studies include field workshops, characterization of terrestrial analog sites, instrument tests, laboratory measurements (including analysis of Martian meteorites), and computer and laboratory modeling. The combination of all these activities allows scientists to constrain the processes operating in specific terrestrial environments and extrapolate how similar processes could affect Mars. The Terrestrial Analogs for Mars Community Panel has considered the following two key questions: (1) How do terrestrial analog studies tie in to the Mars Exploration Payload Assessment Group science questions about life, past climate, and geologic evolution of Mars, and (2) How can future instrumentation be used to address these questions. The panel has considered the issues of data collection, value of field workshops, data archiving, laboratory measurements and modeling, human exploration issues, association with other areas of solar system exploration, and education and public outreach activities.

  11. Reasoning through Instructional Analogies

    Science.gov (United States)

    Kapon, Shulamit; diSessa, Andrea A.

    2012-01-01

    This article aims to account for students' assessments of the plausibility and applicability of analogical explanations, and individual differences in these assessments, by analyzing properties of students' underlying knowledge systems. We developed a model of explanation and change in explanation focusing on knowledge elements that provide a…

  12. The Paradox of Analogy

    Directory of Open Access Journals (Sweden)

    David Botting

    2012-03-01

    Full Text Available I will show that there is a type of analogical reasoning that instantiates a pattern of reasoning in confirmation theory that is considered at best paradoxical and at worst fatal to the entire syntactical approach to confirmation and explanation. However, I hope to elaborate conditions under which this is a sound (although not necessarily strong method of reasoning.

  13. Analogy, explanation, and proof

    Science.gov (United States)

    Hummel, John E.; Licato, John; Bringsjord, Selmer

    2014-01-01

    People are habitual explanation generators. At its most mundane, our propensity to explain allows us to infer that we should not drink milk that smells sour; at the other extreme, it allows us to establish facts (e.g., theorems in mathematical logic) whose truth was not even known prior to the existence of the explanation (proof). What do the cognitive operations underlying the inference that the milk is sour have in common with the proof that, say, the square root of two is irrational? Our ability to generate explanations bears striking similarities to our ability to make analogies. Both reflect a capacity to generate inferences and generalizations that go beyond the featural similarities between a novel problem and familiar problems in terms of which the novel problem may be understood. However, a notable difference between analogy-making and explanation-generation is that the former is a process in which a single source situation is used to reason about a single target, whereas the latter often requires the reasoner to integrate multiple sources of knowledge. This seemingly small difference poses a challenge to the task of marshaling our understanding of analogical reasoning to understanding explanation. We describe a model of explanation, derived from a model of analogy, adapted to permit systematic violations of this one-to-one mapping constraint. Simulation results demonstrate that the resulting model can generate explanations for novel explananda and that, like the explanations generated by human reasoners, these explanations vary in their coherence. PMID:25414655

  14. How Analogy Drives Physics

    International Nuclear Information System (INIS)

    Hofstadter, Doug

    2004-01-01

    Many new ideas in theoretical physics come from analogies to older ideas in physics. For instance, the abstract notion of 'isospin' (or isotopic spin) originated in the prior concept of 'spin' (quantized angular momentum); likewise, the concept of 'phonon' (quantum of sound, or quantized collective excitation of a crystal) was based on the prior concept of 'photon' (quantum of light, or quantized element of the electromagnetic field). But these two examples, far from being exceptions, in fact represent the bread and butter of inventive thinking in physics. In a nutshell, intraphysics analogy-making -- borrowing by analogy with something already known in another area of physics -- is central to the progress of physics. The aim of this talk is to reveal the pervasiveness -- indeed, the indispensability -- of this kind of semi-irrational, wholly intuitive type of thinking (as opposed to more deductive mathematical inference) in the mental activity known as 'doing physics'. Speculations as to why wild analogical leaps are so crucial to the act of discovery in physics (as opposed to other disciplines) will be offered.

  15. Quantum Analog Computing

    Science.gov (United States)

    Zak, M.

    1998-01-01

    Quantum analog computing is based upon similarity between mathematical formalism of quantum mechanics and phenomena to be computed. It exploits a dynamical convergence of several competing phenomena to an attractor which can represent an externum of a function, an image, a solution to a system of ODE, or a stochastic process.

  16. Arsenic (+3 oxidation state) methyltransferase and the inorganic arsenic methylation phenotype

    International Nuclear Information System (INIS)

    Li Jiaxin; Waters, Stephen B.; Drobna, Zuzana; Devesa, Vicenta; Styblo, Miroslav; Thomas, David J.

    2005-01-01

    Inorganic arsenic is enzymatically methylated; hence, its ingestion results in exposure to the parent compound and various methylated arsenicals. Both experimental and epidemiological evidences suggest that some of the adverse health effects associated with chronic exposure to inorganic arsenic may be mediated by these methylated metabolites. If i As methylation is an activation process, then the phenotype for inorganic arsenic methylation may determine risk associated with exposure to this metalloid. We examined inorganic arsenic methylation phenotypes and arsenic (+3 oxidation state) methyltransferase genotypes in four species: three that methylate inorganic arsenic (human (Homo sapiens), rat (Rattus norwegicus), and mouse (Mus musculus)) and one that does not methylate inorganic arsenic (chimpanzee, Pan troglodytes). The predicted protein products from arsenic (+3 oxidation state) methyltransferase are similar in size for rat (369 amino acid residues), mouse (376 residues), and human (375 residues). By comparison, a 275-nucleotide deletion beginning at nucleotide 612 in the chimpanzee gene sequence causes a frameshift that leads to a nonsense mutation for a premature stop codon after amino acid 205. The null phenotype for inorganic arsenic methylation in the chimpanzee is likely due to the deletion in the gene for arsenic (+3 oxidation state) methyltransferase that yields an inactive truncated protein. This lineage-specific loss of function caused by the deletion event must have occurred in the Pan lineage after Homo-Pan divergence about 5 million years ago

  17. Oxidized Nitrogen Balance over 15 Months at Rural and Urban New York State Locations

    Science.gov (United States)

    Schwab, J. J.; Ninneman, M.; Marto, J.; Edgerton, E. S.; Blanchard, C. L.; Shaw, S. L.

    2017-12-01

    Continuous measurements of oxidized nitrogen species (NO, NO2, and HNO3), families of species (NOy, alkyl nitrates [or ANs], and peroxyacetyl nitrates [or PANs]), and particle nitrate (pNO3) were carried out for a fifteen-month period from August 2016 through October 2017 at two locations in New York State. The two sites were a rural research station at Pinnacle State Park in Addison, NY and an urban research station at Queens College in New York City. Four different chemiluminescence analyzers with various converters and denuders were employed to make these measurements. Instrumentation used for the study will be described, as well as some of the challenges created by combining data from these independent analyzers to address the oxidized nitrogen budget at the two sites. The Pinnacle State Park site often experiences quite clean air with low ppb levels of total NOy and a greater fraction of oxidized nitrogen products (NOz species). This contrasts with the urban Queens College location, which experiences stronger NOx sources. Seasonal differences in the NOx/NOy and NOz/NOy ratios, and the makeup of the NOz species, are also significant and will be explored in the presentation.

  18. Single Crystal Growth of Pure Co3+ Oxidation State Material LaSrCoO4

    Directory of Open Access Journals (Sweden)

    Hanjie Guo

    2016-08-01

    Full Text Available We report on the single crystal growth of the single-layer perovskite cobaltate LaSrCoO4 that was grown by the optical floating zone method using high oxygen pressures. Phase purity and single crystallinity were confirmed by X-ray diffraction techniques. The pure Co3+ oxidation state was confirmed by X-ray absorbtion spectroscopy measurements. A transition to a spin glass state is observed at ∼7 K in magnetic susceptibility and specific heat measurements.

  19. Raman spectroscopic study of the oxidation state of Eu in molten LiCl-KCl

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seung; Yun, Jong-Il [KAIST, Daejeon(Korea, Republic of)

    2016-10-15

    Spectroscopy can provide high reliability for the quantitative analysis of such system. The molar absorptivity of Eu(II) at 325 nm is reported as about 1645 M{sup -1}cm{sup -1}, which is too high to apply to higher concentration. A high-temperature Raman spectroscopy has been set and employed for analyzing the molecular structure and coordination complex and investigating the oxidation state of europium in molten LiCl-KCl. Europium can be present in divalent state while many other lanthanides exist in trivalent state. The thermodynamic properties of europium ions have been studied using electrochemical methods, spectroscopic methods, and EPR technique. Although there has been discrepancy of the reduced amount of europium in previous works, the majority of Eu(III) is thought to be reduced to Eu(II) in molten LiCl-KCl spontaneously at relatively low concentration (< 7.5 × 10{sup -4} M). Raman spectroscopy was employed to investigate the oxidation state of EuClx in LiCl-KCl at 500 .deg. C. The Raman scattering results suggest the majority of trivalent europium is reduced to divalent state with the composition change by vaporization. The Raman bands show highly asymmetric structure, quite different from regular octahedral structure.

  20. Molecular water oxidation mechanisms followed by transition metals: state of the art.

    Science.gov (United States)

    Sala, Xavier; Maji, Somnath; Bofill, Roger; García-Antón, Jordi; Escriche, Lluís; Llobet, Antoni

    2014-02-18

    One clean alternative to fossil fuels would be to split water using sunlight. However, to achieve this goal, researchers still need to fully understand and control several key chemical reactions. One of them is the catalytic oxidation of water to molecular oxygen, which also occurs at the oxygen evolving center of photosystem II in green plants and algae. Despite its importance for biology and renewable energy, the mechanism of this reaction is not fully understood. Transition metal water oxidation catalysts in homogeneous media offer a superb platform for researchers to investigate and extract the crucial information to describe the different steps involved in this complex reaction accurately. The mechanistic information extracted at a molecular level allows researchers to understand both the factors that govern this reaction and the ones that derail the system to cause decomposition. As a result, rugged and efficient water oxidation catalysts with potential technological applications can be developed. In this Account, we discuss the current mechanistic understanding of the water oxidation reaction catalyzed by transition metals in the homogeneous phase, based on work developed in our laboratories and complemented by research from other groups. Rather than reviewing all of the catalysts described to date, we focus systematically on the several key elements and their rationale from molecules studied in homogeneous media. We organize these catalysts based on how the crucial oxygen-oxygen bond step takes place, whether via a water nucleophilic attack or via the interaction of two M-O units, rather than based on the nuclearity of the water oxidation catalysts. Furthermore we have used DFT methodology to characterize key intermediates and transition states. The combination of both theory and experiments has allowed us to get a complete view of the water oxidation cycle for the different catalysts studied. Finally, we also describe the various deactivation pathways for

  1. Analogy Mapping Development for Learning Programming

    Science.gov (United States)

    Sukamto, R. A.; Prabawa, H. W.; Kurniawati, S.

    2017-02-01

    Programming skill is an important skill for computer science students, whereas nowadays, there many computer science students are lack of skills and information technology knowledges in Indonesia. This is contrary with the implementation of the ASEAN Economic Community (AEC) since the end of 2015 which is the qualified worker needed. This study provided an effort for nailing programming skills by mapping program code to visual analogies as learning media. The developed media was based on state machine and compiler principle and was implemented in C programming language. The state of every basic condition in programming were successful determined as analogy visualization.

  2. Analog-to-digital conversion

    CERN Document Server

    Pelgrom, Marcel J. M

    2013-01-01

    This textbook is appropriate for use in graduate-level curricula in analog to digital conversion, as well as for practicing engineers in need of a state-of-the-art reference on data converters.  It discusses various analog-to-digital conversion principles, including sampling, quantization, reference generation, nyquist architectures and sigma-delta modulation.  This book presents an overview of the state-of-the-art in this field and focuses on issues of optimizing accuracy and speed, while reducing the power level. This new, second edition emphasizes novel calibration concepts, the specific requirements of new systems, the consequences of 45-nm technology and the need for a more statistical approach to accuracy.  Pedagogical enhancements to this edition include more than twice the exercises available in the first edition, solved examples to introduce all key, new concepts and warnings, remarks and hints, from a practitioner’s perspective, wherever appropriate.  Considerable background information and pr...

  3. Analog forecasting with dynamics-adapted kernels

    Science.gov (United States)

    Zhao, Zhizhen; Giannakis, Dimitrios

    2016-09-01

    Analog forecasting is a nonparametric technique introduced by Lorenz in 1969 which predicts the evolution of states of a dynamical system (or observables defined on the states) by following the evolution of the sample in a historical record of observations which most closely resembles the current initial data. Here, we introduce a suite of forecasting methods which improve traditional analog forecasting by combining ideas from kernel methods developed in harmonic analysis and machine learning and state-space reconstruction for dynamical systems. A key ingredient of our approach is to replace single-analog forecasting with weighted ensembles of analogs constructed using local similarity kernels. The kernels used here employ a number of dynamics-dependent features designed to improve forecast skill, including Takens’ delay-coordinate maps (to recover information in the initial data lost through partial observations) and a directional dependence on the dynamical vector field generating the data. Mathematically, our approach is closely related to kernel methods for out-of-sample extension of functions, and we discuss alternative strategies based on the Nyström method and the multiscale Laplacian pyramids technique. We illustrate these techniques in applications to forecasting in a low-order deterministic model for atmospheric dynamics with chaotic metastability, and interannual-scale forecasting in the North Pacific sector of a comprehensive climate model. We find that forecasts based on kernel-weighted ensembles have significantly higher skill than the conventional approach following a single analog.

  4. Effects of Multimedia and Schema Induced Analogical Reasoning on Science Learning

    Science.gov (United States)

    Zheng, R. Z.; Yang, W.; Garcia, D.; McCadden, E. P.

    2008-01-01

    The present study investigates the effects of multimedia and schema induced analogical reasoning on science learning. It involves 89 fourth grade elementary students in the north-east of the United States. Participants are randomly assigned into four conditions: (a) multimedia with analogy; (b) multimedia without analogy; (c) analogy without…

  5. Application of powerful oxidizers in the synthesis of new high-oxidation state actinide and related species

    International Nuclear Information System (INIS)

    Yeh, S.M.

    1984-11-01

    The fluorinating and oxide scavenging ability of XeF 6 have been studied by bringing XeF 6 into interaction with oxide-fluoride compounds of the third-transition-series elements (W, Re and Os) and uranium, in their highest oxidation states. A + MOF 5 - and A + M 2 O 2 F 9 - (A = K or Cs, M = W or U) were converted to A + MF 7 - by XeF 6 , but the rhenium and osmium compounds, K + ReO 2 F 4 - and XeF 5 + OsO 3 F 3 - , resisted interaction with XeF 6 . Strong interactions between XeF 2 or KrF 2 and the solvent have been observed for their solutions in anhydrous HF. Both XeF 2 and KrF 2 are seen to be effective in breaking up the polymeric (HF)/sub n/ chains. Only weak interactions occur between cations and anions of KrF + AuF 6 - and Kr 2 F 3 + AuF 6 - in HF. The AuF 6 - anions are slightly distorted from O/sub h/ symmetry. Kr 2 F 3 + cations in HF have the same dissymmetric V-shape which occurs in crystalline salts. A low-temperature orthorhombic form, β-ReF 6 + SbF 6 - , a high-temperature rhombohedral form, α-ReF 6 + SbF 6 - , and a ReF 6 + AuF 6 - have been prepared. These compounds possess only kinetic stability at ambient temperature and at approx. 20 0 C are best represented as ReF 6 + ReF 7 MF 6 - MF 5 . Thermochemical energy evaluations indicate that the ionization potential of ReF 6 is 261 kcal mole -1 and that the fluoride-ion affinity of ReF 6 + is -214 kcal mole -1 . This is more exothermal than the corresponding process for IF 6 + (-208 kcal mole -1 ). In contrast, ReOF 5 is shown to be a better fluoro-base than IOF 5 and also is a better base than ReF 7 . ReOF 4 + MF 6 - (M = Sb, Au and As) salts are of higher thermal stability than their ReF 6 + MF 6 - analogues

  6. Synchrotron Micro-XANES Measurements of Vanadium Oxidation State in Glasses as a Function of Oxygen Fugacity: Experimental Calibration of Data Relevant to Partition Coefficient Determination

    Science.gov (United States)

    Delaney, J. S.; Sutton, S. R.; Newville, M.; Jones, J. H.; Hanson, B.; Dyar, M. D.; Schreiber, H.

    2000-01-01

    Oxidation state microanalyses for V in glass have been made by calibrating XANES spectral features with optical spectroscopic measurements. The oxidation state change with fugacity of O2 will strongly influence partitioning results.

  7. Chemical state analysis of oxidation products on steel surface by conversion electron Moessbauer spectrometry

    International Nuclear Information System (INIS)

    Ujihira, Yusuke; Nomura, Kiyoshi

    1978-01-01

    The polished NT-70H steel (Fe: 95.97%, C: 0.56%, diameter: 5 cm, thickness: 0.5 cm) was immersed in deionized water or in solutions containing (0.25 -- 0.5) M of chloride, sulfate and nitrate ions. The chemical states of oxidation products of iron on the surface were identified through the analysis of conversion electron Moessbauer spectra (CEMS). CEMS of the steel surface, which had been dipped in deionized water, revealed that γ-FeOOH was formed on the surface. The thickness of γ-FeOOH layer increased with the increase of the duration of dipping. Dissolved oxygen in the solution played an essential role in the oxidation of iron to γ-FeOOH. Oxidation product of iron dipped in the 0.5 M sodium chloride solution was identified as γ-FeOOH. Amorphous paramagnetic iron (III) compound tended to form in the presence of hydrogen peroxide or ammonium ions in the solutions. The increase of alkalinity of the solution up to pH 12 suppressed the oxidation rate and assisted the formation of green rust, which was confirmed by the appearance of the quadrupole splitting peaks of the green rust. In the 0.25 M sodium sulfate solution, oxidation of the steel surface proceeded slowly and the quadrupole splitting peaks of Fe(OH) 2 were seen in the CEMS. The peak intensity of Fe(OH) 2 gradually decreased and that of γ-FeOOH increased by the extension of immersion of steel in the solution. Magnetite (Fe 3 O 4 ) layer was developed beneath the γ-FeOOH layer, when steel was dipped in 0.5 M sodium nitrate solution. However, the peaks of Fe 3 O 4 were not seen on CEMS of steel surface immersed in 0.5 M ammonium nitrate solution. Thus, applying the feasibility of CEMS for the characterization of oxidated compounds of iron on the steel surface formed by the immersion in solutions, the oxidation mechanism of the steel surface was discussed based upon the results of chemical state analyses. (author)

  8. Room air versus carbon dioxide pneumoperitoneum: effects on oxidative state, apoptosis and histology of splanchnic organs.

    Science.gov (United States)

    Ypsilantis, Petros; Lambropoulou, Maria; Tentes, Ioannis; Chryssidou, Maria; Georgantas, Themistoklis; Simopoulos, Constantinos

    2016-04-01

    Although CO2 is the insufflation gas of choice in laparoscopic procedures, room air is usually used in natural orifice transluminal endoscopic surgery. The aim of the present study was to compare the safety of room air versus CO2 pneumoperitoneum in terms of their effect on the oxidative state, apoptosis and tissue injury of splanchnic organs. Eighteen Wistar rats were assigned to three groups (n = 6 per group) and were subjected to 8 mm Hg room air (group Pne-Air) or CO2 pneumoperitoneum (group Pne-CO2) or sham operation for 60 min. Forty-five minutes postdeflation, tissue samples were excised from the liver, stomach, ileum and kidneys for reduced glutathione-to-glutathione disulfide (GSH/GSSG) ratio, caspase-8 and caspase-3 and hypoxia-inducible factor-1α (HIF-1α) immunohistochemical assessment and histopathologic examination. GSH/GSSG ratio substantially declined in both pneumoperitoneum groups. No change was noted in HIF-1α expression. Mild upregulation of caspase-8 and caspase-3 was noted in both pneumoperitoneum groups being less pronounced in group Pne-Air. Histopathologic score was increased in all organs studied, but the stomach, in both pneumoperitoneum groups. Pneumoperitoneum established by either room air or CO2 induced substantial oxidative stress, mild apoptosis and mild tissue injury in splanchnic organs. While air pneumoperitoneum conferred a less pronounced apoptotic effect, the oxidative state and histopathologic profile of splanchnic organs did not differ between insufflation gases.

  9. The influence of iridium chemical oxidation state on the performance and durability of oxygen evolution catalysts in PEM electrolysis

    Science.gov (United States)

    Siracusano, S.; Baglio, V.; Grigoriev, S. A.; Merlo, L.; Fateev, V. N.; Aricò, A. S.

    2017-10-01

    Nanosized Ir-black (3 nm) and Ir-oxide (5 nm) oxygen evolution electrocatalysts showing high performance in polymer electrolyte membrane (PEM) water electrolysis based on Aquivion® short-side chain ionomer membrane are investigated to understand the role of the Ir oxidation state on the electrocatalytic activity and stability. Despite the smaller mean crystallite size, the Ir-black electrocatalyst shows significantly lower initial performance than the Ir-oxide. During operation at high current density, the Ir-black shows a decrease of cell potential with time whereas the Ir-oxide catalyst shows increasing cell potential resulting in a degradation rate of about 10 μV/h, approaching 1000 h. The unusual behaviour of the Ir-black results from the oxidation of metallic Ir to IrOx. The Ir-oxide catalyst shows instead a hydrated structure on the surface and a negative shift of about 0.5 eV for the Ir 4f binding energy after 1000 h electrolysis operation. This corresponds to the formation of a sub-stoichiometric Ir-oxide on the surface. These results indicate that a hydrated IrO2 with high oxidation state on the surface is favourable in decreasing the oxygen evolution overpotential. Modifications of the Ir chemical oxidation state during operation can affect significantly the catalytic activity and durability of the electrolysis system.

  10. Terrestrial Spaceflight Analogs: Antarctica

    Science.gov (United States)

    Crucian, Brian

    2013-01-01

    Alterations in immune cell distribution and function, circadian misalignment, stress and latent viral reactivation appear to persist during Antarctic winterover at Concordia Station. Some of these changes are similar to those observed in Astronauts, either during or immediately following spaceflight. Others are unique to the Concordia analog. Based on some initial immune data and environmental conditions, Concordia winterover may be an appropriate analog for some flight-associated immune system changes and mission stress effects. An ongoing smaller control study at Neumayer III will address the influence of the hypoxic variable. Changes were observed in the peripheral blood leukocyte distribution consistent with immune mobilization, and similar to those observed during spaceflight. Alterations in cytokine production profiles were observed during winterover that are distinct from those observed during spaceflight, but potentially consistent with those observed during persistent hypobaric hypoxia. The reactivation of latent herpesviruses was observed during overwinter/isolation, that is consistently associated with dysregulation in immune function.

  11. Visible light photoreactivity from hybridization states between carbon nitride bandgap states and valence states in Nb and Ti oxides

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hosik, E-mail: hosiklee@gmail.com [School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology (UNIST), Unist-gil 100 Eonyang-eup, Ulsan 689-798 (Korea, Republic of); Ohno, Takahisa, E-mail: OHNO.Takahisa@nims.go.jp [Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Material Science, 1-2-1 Sengen, Tsukuba (Japan); Computational Materials Science Unit (CMSU), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047 (Japan)

    2013-03-29

    Highlights: ► Origin of bandgap reduction for visible photoreactivity is suggested. ► Carbon nitride adsorption in interlayer space can induce the bandgap reduction. ► The electronic structures are studied by density functional theory calculations. - Abstract: For better efficiency as photocatalysts, N-doping for visible light reactivity has been intensively studied in Lamellar niobic and titanic solid acids (HNb{sub 3}O{sub 8}, H{sub 2}Ti{sub 4}O{sub 9}), and its microscopic structures have been debated in this decade. We calculate the layered solid acids’ structures and bandgaps. Bandgap reduction by carbon nitride adsorption in interlayer space is observed computationally. It originates from localized nitrogen states which form delocalized top-valence states by hybridizing with the host oxygen states and can contribute to photo-current.

  12. Analog storage integrated circuit

    Science.gov (United States)

    Walker, J.T.; Larsen, R.S.; Shapiro, S.L.

    1989-03-07

    A high speed data storage array is defined utilizing a unique cell design for high speed sampling of a rapidly changing signal. Each cell of the array includes two input gates between the signal input and a storage capacitor. The gates are controlled by a high speed row clock and low speed column clock so that the instantaneous analog value of the signal is only sampled and stored by each cell on coincidence of the two clocks. 6 figs.

  13. Analogy, Explanation, and Proof

    Directory of Open Access Journals (Sweden)

    John eHummel

    2014-11-01

    Full Text Available People are habitual explanation generators. At its most mundane, our propensity to explain allows us to infer that we should not drink milk that smells sour; at the other extreme, it allows us to establish facts (e.g., theorems in mathematical logic whose truth was not even known prior to the existence of the explanation (proof. What do the cognitive operations underlying the (inductive inference that the milk is sour have in common with the (deductive proof that, say, the square root of two is irrational? Our ability to generate explanations bears striking similarities to our ability to make analogies. Both reflect a capacity to generate inferences and generalizations that go beyond the featural similarities between a novel problem and familiar problems in terms of which the novel problem may be understood. However, a notable difference between analogy-making and explanation-generation is that the former is a process in which a single source situation is used to reason about a single target, whereas the latter often requires the reasoner to integrate multiple sources of knowledge. This small-seeming difference poses a challenge to the task of marshaling our understanding of analogical reasoning in the service of understanding explanation. We describe a model of explanation, derived from a model of analogy, adapted to permit systematic violations of this one-to-one mapping constraint. Simulation results demonstrate that the resulting model can generate explanations for novel explananda and that, like the explanations generated by human reasoners, these explanations vary in their coherence.

  14. Introducing a Simple Equation to Express Oxidation States as an Alternative to Using Rules Associated with Words Alone

    Science.gov (United States)

    Minkiewicz, Piotr; Darewicz, Malgorzata; Iwaniak, Anna

    2018-01-01

    A simple equation to calculate the oxidation states (oxidation numbers) of individual atoms in molecules and ions may be introduced instead of rules associated with words alone. The equation includes two of three categories of bonds, classified as proposed by Goodstein: number of bonds with more electronegative atoms and number of bonds with less…

  15. Homogeneity of Continuum Model of an Unsteady State Fixed Bed Reactor for Lean CH4 Oxidation

    Directory of Open Access Journals (Sweden)

    Subagjo

    2014-07-01

    Full Text Available In this study, the homogeneity of the continuum model of a fixed bed reactor operated in steady state and unsteady state systems for lean CH4 oxidation is investigated. The steady-state fixed bed reactor system was operated under once-through direction, while the unsteady-state fixed bed reactor system was operated under flow reversal. The governing equations consisting of mass and energy balances were solved using the FlexPDE software package, version 6. The model selection is indispensable for an effective calculation since the simulation of a reverse flow reactor is time-consuming. The homogeneous and heterogeneous models for steady state operation gave similar conversions and temperature profiles, with a deviation of 0.12 to 0.14%. For reverse flow operation, the deviations of the continuum models of thepseudo-homogeneous and heterogeneous models were in the range of 25-65%. It is suggested that pseudo-homogeneous models can be applied to steady state systems, whereas heterogeneous models have to be applied to unsteady state systems.

  16. SOLID STATE ENERGY CONVERSION ALLIANCE (SECA) SOLID OXIDE FUEL CELL PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Minh; Jim Powers

    2003-10-01

    This report summarizes the work performed for April 2003--September 2003 reporting period under Cooperative Agreement DE-FC26-01NT41245 for the U.S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid State Energy Conversion Alliance (SECA) Solid oxide Fuel Cell Program''. During this reporting period, the conceptual system design activity was completed. The system design, including strategies for startup, normal operation and shutdown, was defined. Sealant and stack materials for the solid oxide fuel cell (SOFC) stack were identified which are capable of meeting the thermal cycling and degradation requirements. A cell module was tested which achieved a stable performance of 0.238 W/cm{sup 2} at 95% fuel utilization. The external fuel processor design was completed and fabrication begun. Several other advances were made on various aspects of the SOFC system, which are detailed in this report.

  17. SOLID STATE ENERGY CONVERSION ALLIANCE (SECA) SOLID OXIDE FUEL CELL PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    2003-06-01

    This report summarizes the progress made during the September 2001-March 2002 reporting period under Cooperative Agreement DE-FC26-01NT41245 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid State Energy Conversion Alliance (SECA) Solid Oxide Fuel Cell Program''. The program focuses on the development of a low-cost, high-performance 3-to-10-kW solid oxide fuel cell (SOFC) system suitable for a broad spectrum of power-generation applications. The overall objective of the program is to demonstrate a modular SOFC system that can be configured to create highly efficient, cost-competitive, and environmentally benign power plants tailored to specific markets. When fully developed, the system will meet the efficiency, performance, life, and cost goals for future commercial power plants.

  18. Oxidation and detoxification of trivalent arsenic species

    International Nuclear Information System (INIS)

    Aposhian, H. Vasken; Zakharyan, Robert A.; Avram, Mihaela D.; Kopplin, Michael J.; Wollenberg, Michael L.

    2003-01-01

    Arsenic compounds with a +3 oxidation state are more toxic than analogous compounds with a +5 oxidation state, for example, arsenite versus arsenate, monomethylarsonous acid (MMA III ) versus monomethylarsonic acid (MMA V ), and dimethylarsinous acid (DMA III ) versus dimethylarsinic acid (DMA V ). It is no longer believed that the methylation of arsenite is the beginning of a methylation-mediated detoxication pathway. The oxidation of these +3 compounds to their less toxic +5 analogs by hydrogen peroxide needs investigation and consideration as a potential mechanism for detoxification. Xanthine oxidase uses oxygen to oxidize hypoxanthine to xanthine to uric acid. Hydrogen peroxide and reactive oxygen are also products. The oxidation of +3 arsenicals by the hydrogen peroxide produced in the xanthine oxidase reaction was blocked by catalase or allopurinol but not by scavengers of the hydroxy radical, e.g., mannitol or potassium iodide. Melatonin, the singlet oxygen radical scavenger, did not inhibit the oxidation. The production of H 2 O 2 by xanthine oxidase may be an important route for decreasing the toxicity of trivalent arsenic species by oxidizing them to their less toxic pentavalent analogs. In addition, there are many other reactions that produce hydrogen peroxide in the cell. Although chemists have used hydrogen peroxide for the oxidation of arsenite to arsenate to purify water, we are not aware of any published account of its potential importance in the detoxification of trivalent arsenicals in biological systems. At present, this oxidation of the +3 oxidation state arsenicals is based on evidence from in vitro experiments. In vivo experiments are needed to substantiate the role and importance of H 2 O 2 in arsenic detoxication in mammals

  19. Surface State Capture Cross-Section at the Interface between Silicon and Hafnium Oxide

    Directory of Open Access Journals (Sweden)

    Fu-Chien Chiu

    2013-01-01

    Full Text Available The interfacial properties between silicon and hafnium oxide (HfO2 are explored by the gated-diode method and the subthreshold measurement. The density of interface-trapped charges, the current induced by surface defect centers, the surface recombination velocity, and the surface state capture cross-section are obtained in this work. Among the interfacial properties, the surface state capture cross-section is approximately constant even if the postdeposition annealing condition is changed. This effective capture cross-section of surface states is about 2.4 × 10−15 cm2, which may be an inherent nature in the HfO2/Si interface.

  20. Control of lipid oxidation during exercise: role of energy state and mitochondrial factors

    DEFF Research Database (Denmark)

    Sahlin, K; Harris, R C

    2008-01-01

    Despite considerable progress during recent years our understanding of how lipid oxidation (LOx) is controlled during exercise remains incomplete. This review focuses on the role of mitochondria and energy state in the control of LOx. LOx increases in parallel with increased energy demand up...... to an exercise intensity of about 50-60% of VO(2max) after which the contribution of lipid decreases. The switch from lipid to carbohydrate (CHO) is of energetic advantage due to the increased ATP/O(2) yield. In the low-intensity domain (energy state will stimulate both LOx...... during high-intensity exercise. Another potential mechanism, suggested in this review, is that Acyl-CoA synthetase (ACS), an initial step in LCFA catabolism, functions as a regulator of LOx. ACS activity is suggested to be under control of CoASH and energy state. Furthermore, evidence exists...

  1. Optically induced bistable states in metal/tunnel-oxide/semiconductor /MTOS/ junctions

    Science.gov (United States)

    Lai, S. K.; Dressendorfer, P. V.; Ma, T. P.; Barker, R. C.

    1981-01-01

    A new switching phenomenon in metal-oxide semiconductor tunnel junction has been discovered. With a sufficiently large negative bias applied to the electrode, incident visible light of intensity greater than about 1 microW/sq cm causes the reverse-biased junction to switch from a low-current to a high-current state. It is believed that hot-electron-induced impact ionization provides the positive feedback necessary for switching, and causes the junction to remain in its high-current state after the optical excitation is removed. The junction may be switched back to the low-current state electrically. The basic junction characteristics have been measured, and a simple model for the switching phenomenon has been developed.

  2. 23rd workshop on Advances in Analog Circuit Design

    CERN Document Server

    Baschirotto, Andrea; Makinwa, Kofi

    2015-01-01

    This book is based on the 18 tutorials presented during the 23rd workshop on Advances in Analog Circuit Design.  Expert designers present readers with information about a variety of topics at the frontier of analog circuit design, serving as a valuable reference to the state-of-the-art, for anyone involved in analog circuit research and development.    • Includes coverage of high-performance analog-to-digital and digital to analog converters, integrated circuit design in scaled technologies, and time-domain signal processing; • Provides a state-of-the-art reference in analog circuit design, written by experts from industry and academia; • Presents material in a tutorial-based format.

  3. Evolution of the Oxidation State of the Earth's Mantle: Challenges of High Pressure Quenching

    Science.gov (United States)

    Danielson, L. R.; Righter, K.; Keller, L.; Christoffersen, R.; Rahman, Z.

    2015-01-01

    The oxidation state of the Earth's mantle during formation remains an unresolved question, whether it was constant throughout planetary accretion, transitioned from reduced to oxidized, or from oxidized to reduced. We investigate the stability of Fe3+ at depth, in order to constrain processes (water, late accretion, dissociation of FeO) which may reduce or oxidize the Earth's mantle. Experiments of more mafic compositions and at higher pressures commonly form a polyphase quench intergrowth composed primarily of pyroxenes, with interstitial glass which hosts nearly all of the more volatile minor elements. In our previous experiments on shergottite compositions, variable fO2, T, and P is less than 4 GPa, Fe3+/TotFe decreased slightly with increasing P, similar to terrestrial basalt. For oxidizing experiments less than 7GPa, Fe3+/TotFe decreased as well, but it's unclear from previous modelling whether the deeper mantle could retain significant Fe3+. Our current experiments expand our pressure range deeper into the Earth's mantle and focus on compositions and conditions relevant to the early Earth. Experiments with Knippa basalt as the starting composition were conducted at 1-8 GPa and 1800 C, using a molybdenum capsule to set the fO2 near IW, by buffering with Mo-MoO3. TEM and EELS analyses revealed the run products from 7-8 GPa quenched to polycrystalline phases, with the major phase pyroxene containing approximately equal Fe3+/2+. A number of different approaches have been employed to produce glassy samples that can be measured by EELS and XANES. A more intermediate andesite was used in one experiment, and decompression during quenching was attempted after, but both resulted in a finer grained polyphase texture. Experiments are currently underway to test different capsule materials may affect quench texture. A preliminary experiment using liquid nitrogen to greatly enhance the rate of cooling of the assembly has also been attempted and this technique will be

  4. Component Processes in Analogical Reasoning

    Science.gov (United States)

    Sternberg, Robert J.

    1977-01-01

    Describes alternative theoretical positions regarding (a) the component information processes used in analogical reasoning and (b) strategies for combining these processes. Also presents results from three experiments on analogical reasoning. (Author/RK)

  5. Determination of Model Kinetics for Forced Unsteady State Operation of Catalytic CH4 Oxidation

    Directory of Open Access Journals (Sweden)

    Effendy Mohammad

    2016-01-01

    Full Text Available The catalytic oxidation of methane for abating the emission vented from coal mine or natural gas transportation has been known as most reliable method. A reverse flow reactor operation has been widely used to oxidize this methane emission due to its capability for autothermal operation and heat production. The design of the reverse flow reactor requires a proper kinetic rate expression, which should be developed based on the operating condition. The kinetic rate obtained in the steady state condition cannot be applied for designing the reactor operated under unsteady state condition. Therefore, new approach to develop the dynamic kinetic rate expression becomes indispensable, particularly for periodic operation such as reverse flow reactor. This paper presents a novel method to develop the kinetic rate expression applied for unsteady state operation. The model reaction of the catalytic methane oxidation over Pt/-Al2O3 catalyst was used with kinetic parameter determined from laboratory experiments. The reactor used was a fixed bed, once-through operation, with a composition modulation in the feed gas. The switching time was set at 3 min by varying the feed concentration, feed flow rate, and reaction temperature. The concentrations of methane in the feed and product were measured and analysed using gas chromatography. The steady state condition for obtaining the kinetic rate expression was taken as a base case and as a way to judge its appropriateness to be applied for dynamic system. A Langmuir-Hinshelwood reaction rate model was developed. The time period during one cycle was divided into some segments, depending on the ratio of CH4/O2. The experimental result shows that there were kinetic regimes occur during one cycle: kinetic regime controlled by intrinsic surface reaction and kinetic regime controlled by external diffusion. The kinetic rate obtained in the steady state operation was not appropriate when applied for unsteady state operation

  6. Inductive, Analogical, and Communicative Generalization

    Directory of Open Access Journals (Sweden)

    Adri Smaling

    2003-03-01

    Full Text Available Three forms of inductive generalization - statistical generalization, variation-based generalization and theory-carried generalization - are insufficient concerning case-to-case generalization, which is a form of analogical generalization. The quality of case-to-case generalization needs to be reinforced by setting up explicit analogical argumentation. To evaluate analogical argumentation six criteria are discussed. Good analogical reasoning is an indispensable support to forms of communicative generalization - receptive and responsive (participative generalization — as well as exemplary generalization.

  7. Quantitative chemical state XPS analysis of first row transition metals, oxides and hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Biesinger, M C; Payne, B P; McIntryre, N S [Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Hart, B R; Lau, L Wm [Surface Science Western, Room G1, Western Science Centre, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Grosvenor, A P [Department of Chemistry, Gunning/Lemieux Chemistry Centre, University of Alberta, Edmonton, Alberta, T6G 2G2 (Canada); Smart, R StC [ACeSSS, Applied Centre for Structural and Synchrotron Studies, University of South Australia, Mawson Lakes, SA 5095 (Australia)], E-mail: biesingr@uwo.ca

    2008-03-15

    Practical quantitative chemical state X-ray photoelectron spectroscopy (XPS) analysis of first row transition metals, oxides and hydroxides is challenging due to the complexity of their M 2p spectra. Complex multiplet splitting, shake-up and plasmon loss structure can play a role in the interpretation of the chemical states present. This paper will show practical curve fitting procedures for the quantitative measurement of different chemical states for metal oxides and hydroxides from a survey of transition metals. It will also discuss some of the limitations and pitfalls present as well as give practical examples of their successful use. These curve-fitting procedures are based on 1) standard spectra from quality reference samples, 2) a survey of appropriate literature databases and/or a compilation of literature references, 3) fitting of multiplet split spectra based on spectra of numerous reference materials and theoretical modelling, 4) spectral subtractions routines, again using reference spectra, and 5) specific literature references where fitting procedures are available.

  8. Quantitative chemical state XPS analysis of first row transition metals, oxides and hydroxides

    International Nuclear Information System (INIS)

    Biesinger, M C; Payne, B P; McIntryre, N S; Hart, B R; Lau, L Wm; Grosvenor, A P; Smart, R StC

    2008-01-01

    Practical quantitative chemical state X-ray photoelectron spectroscopy (XPS) analysis of first row transition metals, oxides and hydroxides is challenging due to the complexity of their M 2p spectra. Complex multiplet splitting, shake-up and plasmon loss structure can play a role in the interpretation of the chemical states present. This paper will show practical curve fitting procedures for the quantitative measurement of different chemical states for metal oxides and hydroxides from a survey of transition metals. It will also discuss some of the limitations and pitfalls present as well as give practical examples of their successful use. These curve-fitting procedures are based on 1) standard spectra from quality reference samples, 2) a survey of appropriate literature databases and/or a compilation of literature references, 3) fitting of multiplet split spectra based on spectra of numerous reference materials and theoretical modelling, 4) spectral subtractions routines, again using reference spectra, and 5) specific literature references where fitting procedures are available

  9. Analogical Reasoning and Computer Programming.

    Science.gov (United States)

    Clement, Catherine A.; And Others

    1986-01-01

    A study of correlations between analogical reasoning and Logo programming mastery among female high school students related the results of pretests of analogical reasoning to posttests of programming mastery. A significant correlation was found between analogical reasoning and the ability to write subprocedures for use in several different…

  10. Solid-state electrochromic cell with anodic iridium oxide film electrodes

    International Nuclear Information System (INIS)

    Dautremont-Smith, W.C.; Beni, G.; Schiavone, L.M.; Shay, J.L.

    1979-01-01

    A new solid-state electrochromic cell has been fabricated using an anodic iridium oxide film (AIROF) display electrode. The cell has the symmetric sandwich structure AIROFvertical-barNafionvertical-barAIROF, with the Nafion solid electrolyte opacified by an in situ precipitation technique. A symmetric square-wave voltage of 1.5 V amplitude produces clearly perceivable color changes from pale to dark blue-gray in approx. =1 sec when viewed in diffuse reflection. Good open-circuit optical memory is exhibited:

  11. Analogical scaffolding: Making meaning in physics through representation and analogy

    Science.gov (United States)

    Podolefsky, Noah Solomon

    This work reviews the literature on analogy, introduces a new model of analogy, and presents a series of experiments that test and confirm the utility of this model to describe and predict student learning in physics with analogy. Pilot studies demonstrate that representations (e.g., diagrams) can play a key role in students' use of analogy. A new model of analogy, Analogical Scaffolding, is developed to explain these initial empirical results. This model will be described in detail, and then applied to describe and predict the outcomes of further experiments. Two large-scale (N>100) studies will demonstrate that: (1) students taught with analogies, according to the Analogical Scaffolding model, outperform students taught without analogies on pre-post assessments focused on electromagnetic waves; (2) the representational forms used to teach with analogy can play a significant role in student learning, with students in one treatment group outperforming students in other treatment groups by factors of two or three. It will be demonstrated that Analogical Scaffolding can be used to predict these results, as well as finer-grained results such as the types of distracters students choose in different treatment groups, and to describe and analyze student reasoning in interviews. Abstraction in physics is reconsidered using Analogical Scaffolding. An operational definition of abstraction is developed within the Analogical Scaffolding framework and employed to explain (a) why physicists consider some ideas more abstract than others in physics, and (b) how students conceptions of these ideas can be modeled. This new approach to abstraction suggests novel approaches to curriculum design in physics using Analogical Scaffolding.

  12. N-Oxide-N-oxide interactions and Cl...Cl halogen bonds in pentachloropyridine N-oxide: the many-body approach to interactions in the crystal state.

    Science.gov (United States)

    Wzgarda-Raj, Kinga; Rybarczyk-Pirek, Agnieszka J; Wojtulewski, Sławomir; Palusiak, Marcin

    2018-02-01

    Pentachloropyridine N-oxide, C 5 Cl 5 NO, crystallizes in the monoclinic space group P2 1 /c. In the crystal structure, molecules are linked by C-Cl...Cl halogen bonds into infinite ribbons extending along the crystallographic [100] direction. These molecular aggregates are further stabilized by very short intermolecular N-oxide-N-oxide interactions into herringbone motifs. Computations based on quantum chemistry methods allowed for a more detailed description of the N-oxide-N-oxide interactions and Cl...Cl halogen bonds. For this purpose, Hirshfeld surface analysis and the many-body approach to interaction energy were applied.

  13. Evaluating chemical extraction techniques for the determination of uranium oxidation state in reduced aquifer sediments

    Science.gov (United States)

    Stoliker, Deborah L.; Campbell, Kate M.; Fox, Patricia M.; Singer, David M.; Kaviani, Nazila; Carey, Minna; Peck, Nicole E.; Barger, John R.; Kent, Douglas B.; Davis, James A.

    2013-01-01

    Extraction techniques utilizing high pH and (bi)carbonate concentrations were evaluated for their efficacy in determining the oxidation state of uranium (U) in reduced sediments collected from Rifle, CO. Differences in dissolved concentrations between oxic and anoxic extractions have been proposed as a means to quantify the U(VI) and U(IV) content of sediments. An additional step was added to anoxic extractions using a strong anion exchange resin to separate dissolved U(IV) and U(VI). X-ray spectroscopy showed that U(IV) in the sediments was present as polymerized precipitates similar to uraninite and/or less ordered U(IV), referred to as non-uraninite U(IV) species associated with biomass (NUSAB). Extractions of sediment containing both uraninite and NUSAB displayed higher dissolved uranium concentrations under oxic than anoxic conditions while extractions of sediment dominated by NUSAB resulted in identical dissolved U concentrations. Dissolved U(IV) was rapidly oxidized under anoxic conditions in all experiments. Uraninite reacted minimally under anoxic conditions but thermodynamic calculations show that its propensity to oxidize is sensitive to solution chemistry and sediment mineralogy. A universal method for quantification of U(IV) and U(VI) in sediments has not yet been developed but the chemical extractions, when combined with solid-phase characterization, have a narrow range of applicability for sediments without U(VI).

  14. Analysis of Recurrent Analog Neural Networks

    Directory of Open Access Journals (Sweden)

    Z. Raida

    1998-06-01

    Full Text Available In this paper, an original rigorous analysis of recurrent analog neural networks, which are built from opamp neurons, is presented. The analysis, which comes from the approximate model of the operational amplifier, reveals causes of possible non-stable states and enables to determine convergence properties of the network. Results of the analysis are discussed in order to enable development of original robust and fast analog networks. In the analysis, the special attention is turned to the examination of the influence of real circuit elements and of the statistical parameters of processed signals to the parameters of the network.

  15. Discrete Calculus by Analogy

    CERN Document Server

    Izadi, F A; Bagirov, G

    2009-01-01

    With its origins stretching back several centuries, discrete calculus is now an increasingly central methodology for many problems related to discrete systems and algorithms. The topics covered here usually arise in many branches of science and technology, especially in discrete mathematics, numerical analysis, statistics and probability theory as well as in electrical engineering, but our viewpoint here is that these topics belong to a much more general realm of mathematics; namely calculus and differential equations because of the remarkable analogy of the subject to this branch of mathemati

  16. Nanoscale probing of bandgap states on oxide particles using electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qianlang [School for the Engineering of Matter, Transport and Energy, Arizona State University, 85287 AZ (United States); March, Katia [Laboratoire de Physique des Solides, Bâtiment 510, Université Paris-Sud, 91405 Orsay Cedex (France); Crozier, Peter A., E-mail: CROZIER@asu.edu [School for the Engineering of Matter, Transport and Energy, Arizona State University, 85287 AZ (United States)

    2017-07-15

    Surface and near-surface electronic states were probed with nanometer spatial resolution in MgO and TiO{sub 2} anatase nanoparticles using ultra-high energy resolution electron energy-loss spectroscopy (EELS) coupled to a scanning transmission electron microscope (STEM). This combination allows the surface electronic structure determined with spectroscopy to be correlated with nanoparticle size, morphology, facet etc. By acquiring the spectra in aloof beam mode, radiation damage to the surface can be significantly reduced while maintaining the nanometer spatial resolution. MgO and TiO{sub 2} showed very different bandgap features associated with the surface/sub-surface layer of the nanoparticles. Spectral simulations based on dielectric theory and density of states models showed that a plateau feature found in the pre-bandgap region in the spectra from (100) surfaces of 60 nm MgO nanocubes is consistent with a thin hydroxide surface layer. The spectroscopy shows that this hydroxide species gives rise to a broad filled surface state at 1.1 eV above the MgO valence band. At the surfaces of TiO{sub 2} nanoparticles, pronounced peaks were observed in the bandgap region, which could not be well fitted to defect states. In this case, the high refractive index and large particle size may make Cherenkov or guided light modes the likely causes of the peaks. - Highlights: • Bandgap states detected with aloof beam monochromated EELS on oxide nanoparticle surfaces. • Dielectric theory applied to simulate the spectra and interpret surface structure. • Density of states models also be employed to understand the surface electronic structure. • In MgO, one states associate with water species was found close to the valence band edge. • In anatase, two mid-gap states associated with point defects were found.

  17. Adsorption of CO, CO2, H2, and H2O on titania surfaces with different oxidation states

    International Nuclear Information System (INIS)

    Raupp, G.B.; Dumesic, J.A.

    1985-01-01

    The adsorptive properties of titania surfaces with different oxidation states were proved by temperature-programmed desorption (TPD) of CO, H 2 , CO 2 , and H 2 O. Auger electron spectroscopy and X-ray photoelectron spectroscopy revealed that vacuum annealing an oxidized titanium foil at temperatures from 300 to 800 K was an effective means of systematically varying the average surface oxidation state from Ti 4+ to Ti 2+ . Carbon monoxide weakly adsorbed (desorption energy of 44-49 kJ x mol -1 ) in a carbonyl fashion on coordinatively unsaturated cation sites. Titania surfaces were inert with respect to H 2 adsorption and dissociation. Carbon dioxide adsorbed in a linear molecular fashion. Water adsorbed both molecularly and dissociatively. Results are discussed in terms of the role of titania oxidation state in CO hydrogenation over titania-supported metal catalysts. 74 references, 7 figures

  18. The effect of interfaces on solid-state reactions between oxides

    International Nuclear Information System (INIS)

    Johnson, M.T.; Carter, C.B.

    1998-01-01

    A thin-film geometry has been used to study fundamental solid-state reaction processes occurring at interfaces in two spinel-forming oxide systems. In the first system, NiO/Al 2 O 3 , epitactic NiO films were deposited on various orientations of single-crystal α-Al 2 O 3 . In this case, the reaction kinetics were studied and correlated with the interfacial structure (or substrate orientation). In the second, In 2 O 3 /MgO, solid-state reactions were studied under the influence of an electric field. The electric field provides a driving force for mass transport that affects both the reaction process and the morphological stability of an interface

  19. Chemical states of fission products in irradiated uranium-plutonium mixed oxide fuel

    International Nuclear Information System (INIS)

    Kurosaki, Ken; Uno, Masayoshi; Yamanaka, Shinsuke

    1999-01-01

    The chemical states of fission products (FPs) in irradiated uranium-plutonium mixed oxide (MOX) fuel for the light water reactor (LWR) were estimated by thermodynamic equilibrium calculations on system of fuel and FPs by using ChemSage program. A stoichiometric MOX containing 6.1 wt. percent PuO 2 was taken as a loading fuel. The variation of chemical states of FPs was calculated as a function of oxygen potential. Some pieces of information obtained by the calculation were compared with the results of the post-irradiation examination (PIE) of UO 2 fuel. It was confirmed that the multicomponent and multiphase thermodynamic equilibrium calculation between fuel and FPs system was an effective tool for understanding the behavior of FPs in fuel. (author)

  20. Origin of major donor states in In–Ga–Zn oxide

    Energy Technology Data Exchange (ETDEWEB)

    Nakashima, Motoki; Oota, Masashi; Ishihara, Noritaka; Nonaka, Yusuke; 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)

    2014-12-07

    To clarify the origin of the major donor states in indium gallium zinc oxide (IGZO), we report measurement results and an analysis of several physical properties of IGZO thin films. Specifically, the concentration of H atoms and O vacancies (V{sub O}), carrier concentration, and conductivity are investigated by hard X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, thermal desorption spectroscopy, and Hall effect measurements. The results of these experiments suggest that the origin of major donor states is H occupancy of V{sub O} sites. Furthermore, we use first-principles calculations to investigate the influence of the coexistence of V{sub O} and H in crystalline InGaO{sub 3}(ZnO){sub m} (m = 1). The results indicate that when H is trapped in V{sub O}, a stable complex is created that serves as a shallow-level donor.

  1. Solid-State Electrochromic Device Consisting of Amorphous WO3 and Various Thin Oxide Layers

    Science.gov (United States)

    Shizukuishi, Makoto; Shimizu, Isamu; Inoue, Eiichi

    1980-11-01

    A mixed oxide containing Cr2O3 was introduced into an amorphous WO3 solid-state electrochromic device (ECD) in order to improve its colour memory effect. The electrochromic characteristics were greatly affected by the chemical constituents of a dielectric layer on the a-WO3 layer. Particularly, long memory effect and low power dissipation were attained in a solid-state ECD consisting of a-WO3 and Cr2O3\\cdotV2O5(50 wt.%). Some electrochromic characteristics of the a-WO3/Cr2O3\\cdotV2O5 ECD and the role of V2O5 were investigated.

  2. Long-living positron and positronium states in zeolites and microcrystalline oxides

    International Nuclear Information System (INIS)

    Kajcsos, Zs.; Liszkay, L.; Varga, L.; Lohonyai, L.; Lazar, K.

    1995-01-01

    Positron annihilation (PA) investigation were performed on zeolites (X, Y and ZSM-5) and on microcrystalline MgO, Al 2 O 3 and SiO 2 , providing long lifetime components attributed to o-Ps atoms. In addition to the positron lifetime (LT) measurements, the energy distribution (ED) of the annihilation gamma radiation spectrum was recorded in the 30 keV - 1.5 MeV range for different samples and was compared to reference distributions for Si and GaAs samples, where no long-living Ps states are formed. Apart from the strong correlation with the water content in the samples, the positron data collected testify much more pronounced positronium hosting features for powders of the mentioned oxides than for zeolites. Positron LT spectroscopy combined with recording of the ED of the annihilation radiation provides reliable information on the forming of long living 3γ states. (author) 15 refs.; 4 figs

  3. The state of itinerant charge carriers and thermoelectric effects in correlated oxide metals

    International Nuclear Information System (INIS)

    Kuzemsky, A.L.; Abdus Salam International Centre for Theoretical Physics, Trieste

    2000-10-01

    We analyzed the physics of transport processes and, in particular, the thermoelectric power in the mercurocuprates and other cuprates to get a better insight into the state of the carriers in these compounds. The actual problems related to the complicated mechanisms of carriers scattering above Tc are discussed. The experimental studies of thermoelectric power showed that the state of carriers in cuprates can be influenced by many complicated scattering processes, however the underlying mechanism for the linear decreasing of the TEP with increasing the temperature for most hole-doped HTSC cuprates is still not yet known. The actual problems related to the complicated mechanisms of carriers scattering above Tc are discussed for a few models of charge transport. A comparison between the analytical and experimental results is also made. It is concluded that the crucial factor for the understanding of the transport properties of correlated oxide metals is the nature of itinerant charge carriers, i.e. renormalized quasiparticles. (author)

  4. Probing the transition state region in catalytic CO oxidation on Ru

    Energy Technology Data Exchange (ETDEWEB)

    Ostrom, H. [Stockholm Univ. (Sweden); Oberg, H. [Stockholm Univ. (Sweden); Xin, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); LaRue, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Beye, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Dell' Angela, M. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Gladh, J. [Stockholm Univ. (Sweden); Ng, M. L. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Sellberg, J. A. [Stockholm Univ. (Sweden); SLAC National Accelerator Lab., Menlo Park, CA (United States); Kaya, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Mercurio, G. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Nordlund, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hantschmann, M. [Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Hieke, F. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Kuhn, D. [Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Schlotter, W. F. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Dakovski, G. L. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Turner, J. J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Minitti, M. P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Mitra, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Moeller, S. P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Fohlisch, A. [Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Univ. Potsdam, Potsdam (Germany); Wolf, M. [Fritz-Haber Institute of the Max-Planck-Society, Berlin (Germany); Wurth, W. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); DESY Photon Science, Hamburg (Germany); Persson, M. [The Univ. of Liverpool, Liverpool (United Kingdom); Norskov, J. K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Abild-Pedersen, F. [Stanford Univ., Stanford, CA (United States); Ogasawara, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Pettersson, L. G. M. [Stockholm Univ. (Sweden); Nilsson, A. [Stockholm Univ. (Sweden); SLAC National Accelerator Lab., Menlo Park, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-02-12

    Femtosecond x-ray laser pulses are used to probe the CO oxidation reaction on ruthenium (Ru) initiated by an optical laser pulse. On a time scale of a few hundred femtoseconds, the optical laser pulse excites motions of CO and O on the surface, allowing the reactants to collide, and, with a transient close to a picosecond (ps), new electronic states appear in the O K-edge x-ray absorption spectrum. Density functional theory calculations indicate that these result from changes in the adsorption site and bond formation between CO and O with a distribution of OC–O bond lengths close to the transition state (TS). After 1 ps, 10% of the CO populate the TS region, which is consistent with predictions based on a quantum oscillator model.

  5. Oxidative stress markers in hypertensive states of pregnancy: preterm and term disease.

    Directory of Open Access Journals (Sweden)

    Lesia Olha Kurlak

    2014-08-01

    Full Text Available Discussion continues as to whether de novo hypertension in pregnancy with significant proteinuria (pre-eclampsia; PE and non-proteinuric new hypertension (gestational hypertension; GH are parts of the same disease spectrum or represent different conditions. Non-pregnant hypertension, pregnancy and PE are all associated with oxidative stress. We have established a 6 weeks post-partum clinic for women who experienced a hypertensive pregnancy. We hypothesized that PE and GH could be distinguished by markers of oxidative stress; thiobarbituric acid reactive substances (TBARS and antioxidants (ferric ion reducing ability of plasma; FRAP. Since the severity of PE and GH is greater pre-term, we also compared pre-term and term disease. Fifty-eight women had term PE, 23 pre-term PE, 60 had term GH and 6 pre-term GH, 11 pre-existing (essential hypertension (EH without PE. Limited data were available from normotensive pregnancies (n=7 and non-pregnant controls (n=14. There were no differences in postpartum TBARS or FRAP between hypertensive states; TBARS (P=0.001 and FRAP (P=0.009 were lower in plasma of non-pregnant controls compared to recently-pregnant women. Interestingly FRAP was higher in preterm than term GH (P=0.013. In PE and GH, TBARS correlated with low density lipoprotein (LDL-cholesterol (P=0.036; this association strengthened with inclusion of EH ((P=0.011. The 10 year Framingham index for cardiovascular risk was positively associated with TBARS (P=0.003.Oxidative stress profiles do not differ between hypertensive states but appear to distinguish between recently-pregnant and non-pregnant states. This suggests that pregnancy may alter vascular integrity with changes remaining 6 weeks postpartum. LDL-cholesterol is a known determinant of oxidative stress in cardiovascular disease and we have shown this association to be present in hypertensive pregnancy further emphasizing that such a pregnancy may be revealing a pre-existing cardiovascular

  6. Theoretical studies of positron states and annihilation characteristics at the oxidized Cu(100) surface

    Energy Technology Data Exchange (ETDEWEB)

    Fazleev, N. G. [Department of Physics, Box 19059, University of Texas at Arlington, Arlington Texas 76019 (United States) and Institute of Physics, Kazan Federal University, Kremlevskaya18, Kazan 420008 (Russian Federation); Weiss, A. H. [Department of Physics, Box 19059, University of Texas at Arlington, Arlington Texas 76019 (United States)

    2013-04-19

    In this work we present the results of theoretical studies of positron surface and bulk states and annihilation probabilities of surface-trapped positrons with relevant core electrons at the oxidized Cu(100) surface under conditions of high oxygen coverage. An ab-initio study of the electronic properties of the Cu(100) missing row reconstructed surface at various on surface and sub-surface oxygen coverages has been performed on the basis of the density functional theory (DFT) using the Dmol3 code and the generalized gradient approximation (GGA). Surface structures in calculations have been constructed by adding oxygen atoms to various surface hollow and sub-surface octahedral sites of the 0.5 monolayer (ML) missing row reconstructed phase of the Cu(100) surface with oxygen coverages ranging from 0.5 to 1.5 ML. The charge redistribution at the surface and variations in atomic structure and chemical composition of the topmost layers associated with oxidation and surface reconstruction have been found to affect the spatial extent and localization of the positron surface state wave function and annihilation probabilities of surface trapped positrons with relevant core electrons. Theoretical results are compared with experimental data obtained from studies of oxidation of the Cu(100) surface using positron annihilation induced Auger electron spectroscopy (PAES). It has been shown that positron annihilation probabilities with Cu 3s and 3p core electrons decrease when total (on-surface and sub-surface) oxygen coverage of the Cu(100) surface increases up to 1 ML. The calculations show that for high oxygen coverage when total oxygen coverage is 1. 5 ML the positron is not bound to the surface.

  7. Obesity-Associated Oxidative Stress: Strategies Finalized to Improve Redox State

    Directory of Open Access Journals (Sweden)

    Valeria Gasperi

    2013-05-01

    Full Text Available Obesity represents a major risk factor for a plethora of severe diseases, including diabetes, cardiovascular disease, non-alcoholic fatty liver disease, and cancer. It is often accompanied by an increased risk of mortality and, in the case of non-fatal health problems, the quality of life is impaired because of associated conditions, including sleep apnea, respiratory problems, osteoarthritis, and infertility. Recent evidence suggests that oxidative stress may be the mechanistic link between obesity and related complications. In obese patients, antioxidant defenses are lower than normal weight counterparts and their levels inversely correlate with central adiposity; obesity is also characterized by enhanced levels of reactive oxygen or nitrogen species. Inadequacy of antioxidant defenses probably relies on different factors: obese individuals may have a lower intake of antioxidant- and phytochemical-rich foods, such as fruits, vegetables, and legumes; otherwise, consumption of antioxidant nutrients is normal, but obese individuals may have an increased utilization of these molecules, likewise to that reported in diabetic patients and smokers. Also inadequate physical activity may account for a decreased antioxidant state. In this review, we describe current concepts in the meaning of obesity as a state of chronic oxidative stress and the potential interventions to improve redox balance.

  8. Obesity-Associated Oxidative Stress: Strategies Finalized to Improve Redox State

    Science.gov (United States)

    Savini, Isabella; Catani, Maria Valeria; Evangelista, Daniela; Gasperi, Valeria; Avigliano, Luciana

    2013-01-01

    Obesity represents a major risk factor for a plethora of severe diseases, including diabetes, cardiovascular disease, non-alcoholic fatty liver disease, and cancer. It is often accompanied by an increased risk of mortality and, in the case of non-fatal health problems, the quality of life is impaired because of associated conditions, including sleep apnea, respiratory problems, osteoarthritis, and infertility. Recent evidence suggests that oxidative stress may be the mechanistic link between obesity and related complications. In obese patients, antioxidant defenses are lower than normal weight counterparts and their levels inversely correlate with central adiposity; obesity is also characterized by enhanced levels of reactive oxygen or nitrogen species. Inadequacy of antioxidant defenses probably relies on different factors: obese individuals may have a lower intake of antioxidant- and phytochemical-rich foods, such as fruits, vegetables, and legumes; otherwise, consumption of antioxidant nutrients is normal, but obese individuals may have an increased utilization of these molecules, likewise to that reported in diabetic patients and smokers. Also inadequate physical activity may account for a decreased antioxidant state. In this review, we describe current concepts in the meaning of obesity as a state of chronic oxidative stress and the potential interventions to improve redox balance. PMID:23698776

  9. Oxidation state of sulfur, iron and tin at the surface of float glasses

    International Nuclear Information System (INIS)

    Lagarde, P; Flank, A-M; Jupille, J; Montigaud, H

    2009-01-01

    Sulfur is an important element of glasses, not because of its amount, always very low (less than 0.4 % in weight of SO 3 ), but because of its role since it actively participates to the refinement process and, combined to other elements, it can be responsible for the coloration of the glass. Iron is also of a major importance in most of the glasses. In the case of the float glass, the two faces, because of the fabrication process, are different in terms of composition (presence of Sn for one face) and also in terms of oxidation state of these minority elements (Fe, Sn, S). There should be a subtle interplay between the concentrations and the oxidation states of these different minority elements, and anyway these variations occur over a thickness of the order of few micrometers below the surface. Using the high intensity and the focusing properties (3 x 3 μm 2 ) of the x-ray beam from the Lucia beamline, we have therefore studied the speciation of iron and sulfur near the face of a float glass in relation with the behavior of tin. This has been obtained by combining elemental x-ray fluorescence cartography and x-ray micro-absorption at the different K-edges.

  10. Oxidation state of sulfur, iron and tin at the surface of float glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lagarde, P; Flank, A-M [Synchrotron SOLEIL, l' Orme des Merisiers, BP 48 91192 Gif/Yvette cedex (France); Jupille, J [IMPMC, Universite P. and M. Curie, Campus de Boucicaut, 140 rue de Lourmel 75015 Paris (France); Montigaud, H [Saint-Gobain Recherche 39, quai Lucien Lefranc, BP 135 93303 Aubervilliers Cedex (France)

    2009-11-15

    Sulfur is an important element of glasses, not because of its amount, always very low (less than 0.4 % in weight of SO{sub 3}), but because of its role since it actively participates to the refinement process and, combined to other elements, it can be responsible for the coloration of the glass. Iron is also of a major importance in most of the glasses. In the case of the float glass, the two faces, because of the fabrication process, are different in terms of composition (presence of Sn for one face) and also in terms of oxidation state of these minority elements (Fe, Sn, S). There should be a subtle interplay between the concentrations and the oxidation states of these different minority elements, and anyway these variations occur over a thickness of the order of few micrometers below the surface. Using the high intensity and the focusing properties (3 x 3 {mu}m{sup 2}) of the x-ray beam from the Lucia beamline, we have therefore studied the speciation of iron and sulfur near the face of a float glass in relation with the behavior of tin. This has been obtained by combining elemental x-ray fluorescence cartography and x-ray micro-absorption at the different K-edges.

  11. Albert Einstein, Analogizer Extraordinaire

    CERN Multimedia

    CERN. Geneva

    2007-01-01

    Where does deep insight in physics come from? It is tempting to think that it comes from the purest and most precise of reasoning, following ironclad laws of thought that compel the clear mind completely rigidly. And yet the truth is quite otherwise. One finds, when one looks closely at any major discovery, that the greatest of physicists are, in some sense, the most crazily daring and irrational of all physicists. Albert Einstein exemplifies this thesis in spades. In this talk I will describe the key role, throughout Albert Einstein's fabulously creative life, played by wild guesses made by analogy lacking any basis whatsoever in pure reasoning. In particular, in this year of 2007, the centenary of 1907, I will describe how over the course of two years (1905 through 1907) of pondering, Einstein slowly came, via analogy, to understand the full, radical consequences of the equation that he had first discovered and published in 1905, arguably the most famous equation of all time: E = mc2.

  12. 25th workshop on Advances in Analog Circuit Design

    CERN Document Server

    Harpe, Pieter; Makinwa, Kofi

    2017-01-01

    This book is based on the 18 tutorials presented during the 25th workshop on Advances in Analog Circuit Design. Expert designers present readers with information about a variety of topics at the frontier of analog circuit design, including low-power and energy-efficient analog electronics, with specific contributions focusing on the design of continuous-time sigma-delta modulators, automotive electronics, and power management. This book serves as a valuable reference to the state-of-the-art, for anyone involved in analog circuit research and development.

  13. On the prospects of application and development of solid-state photomultipliers for the task of analog detecting of pulsed optical signals

    Science.gov (United States)

    Bogdanov, S. V.; Kolobov, N. A.; Levin, E. V.; Pozdnyakov, Y. I.; Shubin, V. E.; Shushakov, D. A.; Sitarsky, K. Yu.; Torgovnikov, R. A.

    2018-02-01

    In this paper, we analyze the influence of the crosstalk level and the dynamic range on the basic characteristics of a silicon solid-state photomultiplier and demonstrate their importance for detecting of optical signals with backlight illumination, in particular, for LIDAR application. Experimental results obtained in the study of threshold and fluctuation parameters of detectors with different levels of crosstalk and dynamic range are presented. It is shown that the detector design combining a high dynamic range with a small crosstalk gives a noticeable advantage in such applications.

  14. Towards the improvement of the oxidation resistance of Nb-silicides in situ composites: A solid state diffusion approach

    International Nuclear Information System (INIS)

    Mathieu, S.; Knittel, S.; François, M.; Portebois, L.; Mathieu, S.; Vilasi, M.

    2014-01-01

    Highlights: •Local equilibrium is attained during oxidation at phase boundaries (steady state conditions). •A solid state diffusion model explains the oxidation mechanism of Nb-silicides composites. •The Nb ss fraction is not the only parameters governing the oxidation rate of Nb-silicides. •Aluminium increases the thermodynamic activity of Si in the Nb-silicides composites. •The results indicate the need to develop a Nb–Ti–Hf–Al–Cr–Si thermodynamic database. -- Abstract: The present study focuses on the oxidation mechanism of Nb-silicide composites and on the effect of the composition on the oxidation rate at 1100 °C. A theoretical approach is proposed based on experimental results and used to optimise the oxidation resistance. The growth model based on multiphase diffusion was experimentally tested and confirmed by manufacturing seven composites with different compositions. It was also found that the effect of the composition has to be evaluated at 1100 °C within a short time duration (50 h), where the oxide scale and the internal oxidation zone both grow according to parabolic kinetics

  15. Effect of surface state on the oxidation behavior of welded 308L in simulated nominal primary water of PWR

    Science.gov (United States)

    Ming, Hongliang; Zhang, Zhiming; Wang, Jiazhen; Zhu, Ruolin; Ding, Jie; Wang, Jianqiu; Han, En-Hou; Ke, Wei

    2015-05-01

    The oxidation behavior of 308L weld metal (WM) with different surface state in the simulated nominal primary water of pressurized water reactor (PWR) was studied by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) analyzer and X-ray photoelectron spectroscopy (XPS). After 480 h immersion, a duplex oxide film composed of a Fe-rich outer layer (Fe3O4, Fe2O3 and a small amount of NiFe2O4, Ni(OH)2, Cr(OH)3 and (Ni, Fe)Cr2O4) and a Cr-rich inner layer (FeCr2O4 and NiCr2O4) can be formed on the 308L WM samples with different surface state. The surface state has no influence on the phase composition of the oxide films but obviously affects the thickness of the oxide films and the morphology of the oxides (number & size). With increasing the density of dislocations and subgrain boundaries in the cold-worked superficial layer, the thickness of the oxide film, the number and size of the oxides decrease.

  16. Cellulose nanofibril/reduced graphene oxide/carbon nanotube hybrid aerogels for highly flexible and all-solid-state supercapacitors

    Science.gov (United States)

    Qifeng Zheng; Zhiyong Cai; Zhenqiang Ma; Shaoqin Gong

    2015-01-01

    A novel type of highly flexible and all-solid-state supercapacitor that uses cellulose nanofibril (CNF)/reduced graphene oxide (RGO)/carbon nanotube (CNT) hybrid aerogels as electrodes and H2SO4 poly (vinyl alcohol) PVA gel as the electrolyte was developed and is reported here. These flexible solid-state supercapacitors...

  17. Moessbauer effect study of oxidation and coordination states of iron in some sodium borate glasse:;

    International Nuclear Information System (INIS)

    Eissa, N.A.; Sanad, A.M.; Youssef, S.M.; El-Henawii, S.A.; Gomaa, S.Sh.; Mostafa, A.G.

    1980-01-01

    A structural study of some sodium borate glasses containing iron was carried out applying ME spectroscopy. Both oxidation and coordination states of iron were investigated under the effect of gradual replacing of sodium carbonate by sodium nitrate in the glass batches. The glasses were melted in porcelain crucibles using an electrically heated furnace at 1000+-10 deg C, then were quenched on a steel plate at room temperature (R.T.). The ME source was 20 mCi radioactive Co-57 in chromium. The obtained ME spectra indicated that at lower sodium nitrate content both Fe 2+ and Fe 3+ are present in these glasses. At moderate concentrations some Fe 3+ ions were separated in a crystalline phase and the rest of the iron ions appeared as ferric ions in glassy state. At high sodium nitrate content only Fe 3+ ions in glassy state were detected. The values of the ME parameters for all iron ions indicated that all of them are in the octahedral coordination state. The density measurements confirm the separation of a crystalline phase at moderate sodium nitrate content. (author)

  18. Detecting analogical resemblance without retrieving the source analogy.

    Science.gov (United States)

    Kostic, Bogdan; Cleary, Anne M; Severin, Kaye; Miller, Samuel W

    2010-06-01

    We examined whether people can detect analogical resemblance to an earlier experimental episode without being able to recall the experimental source of the analogical resemblance. We used four-word analogies (e.g., robin-nest/beaver-dam), in a variation of the recognition-without-cued-recall method (Cleary, 2004). Participants studied word pairs (e.g., robin-nest) and were shown new word pairs at test, half of which analogically related to studied word pairs (e.g., beaver-dam) and half of which did not. For each test pair, participants first attempted to recall an analogically similar pair from the study list. Then, regardless of whether successful recall occurred, participants were prompted to rate the familiarity of the test pair, which was said to indicate the likelihood that a pair that was analogically similar to the test pair had been studied. Across three experiments, participants demonstrated an ability to detect analogical resemblance without recalling the source analogy. Findings are discussed in terms of their potential relevance to the study of analogical reasoning and insight, as well as to the study of familiarity and recognition memory.

  19. Quantum State-Resolved Collision Dynamics of Nitric Oxide at Ionic Liquid and Molten Metal Surfaces

    Science.gov (United States)

    Zutz, Amelia Marie

    Detailed molecular scale interactions at the gas-liquid interface are explored with quantum state-to-state resolved scattering of a jet-cooled beam of NO(2pi1/2; N = 0) from ionic liquid and molten metal surfaces. The scattered distributions are probed via laser-induced fluorescence methods, which yield rotational and spin-orbit state populations that elucidate the dynamics of energy transfer at the gas-liquid interface. These collision dynamics are explored as a function of incident collision energy, surface temperature, scattering angle, and liquid identity, all of which are found to substantially affect the degree of rotational, electronic and vibrational excitation of NO via collisions at the liquid surface. Rotational distributions observed reveal two distinct scattering pathways, (i) molecules that trap, thermalize and eventually desorb from the surface (trapping-desorption, TD), and (ii) those that undergo prompt recoil (impulsive scattering, IS) prior to complete equilibration with the liquid surface. Thermally desorbing NO molecules are found to have rotational temperatures close to, but slightly cooler than the surface temperature, indicative of rotational dependent sticking probabilities on liquid surfaces. Nitric oxide is a radical with multiple low-lying electronic states that serves as an ideal candidate for exploring nonadiabatic state-changing collision dynamics at the gas-liquid interface, which induce significant excitation from ground (2pi1/2) to excited (2pi 3/2) spin-orbit states. Molecular beam scattering of supersonically cooled NO from hot molten metals (Ga and Au, Ts = 300 - 1400 K) is also explored, which provide preliminary evidence for vibrational excitation of NO mediated by thermally populated electron-hole pairs in the hot, conducting liquid metals. The results highlight the presence of electronically nonadiabatic effects and build toward a more complete characterization of energy transfer dynamics at gas-liquid interfaces.

  20. Feedback in analog circuits

    CERN Document Server

    Ochoa, Agustin

    2016-01-01

    This book describes a consistent and direct methodology to the analysis and design of analog circuits with particular application to circuits containing feedback. The analysis and design of circuits containing feedback is generally presented by either following a series of examples where each circuit is simplified through the use of insight or experience (someone else’s), or a complete nodal-matrix analysis generating lots of algebra. Neither of these approaches leads to gaining insight into the design process easily. The author develops a systematic approach to circuit analysis, the Driving Point Impedance and Signal Flow Graphs (DPI/SFG) method that does not require a-priori insight to the circuit being considered and results in factored analysis supporting the design function. This approach enables designers to account fully for loading and the bi-directional nature of elements both in the feedback path and in the amplifier itself, properties many times assumed negligible and ignored. Feedback circuits a...

  1. Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries.

    Science.gov (United States)

    Yabuuchi, Naoaki; Nakayama, Masanobu; Takeuchi, Mitsue; Komaba, Shinichi; Hashimoto, Yu; Mukai, Takahiro; Shiiba, Hiromasa; Sato, Kei; Kobayashi, Yuki; Nakao, Aiko; Yonemura, Masao; Yamanaka, Keisuke; Mitsuhara, Kei; Ohta, Toshiaki

    2016-12-23

    Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn 4+ with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3d transition metal elements. The material delivers a reversible capacity of 300 mAh g -1 based on solid-state redox reaction of oxide ions.

  2. Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries

    Science.gov (United States)

    Yabuuchi, Naoaki; Nakayama, Masanobu; Takeuchi, Mitsue; Komaba, Shinichi; Hashimoto, Yu; Mukai, Takahiro; Shiiba, Hiromasa; Sato, Kei; Kobayashi, Yuki; Nakao, Aiko; Yonemura, Masao; Yamanaka, Keisuke; Mitsuhara, Kei; Ohta, Toshiaki

    2016-01-01

    Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn4+ with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3d transition metal elements. The material delivers a reversible capacity of 300 mAh g−1 based on solid-state redox reaction of oxide ions. PMID:28008955

  3. Role of the oxidation state of cerium on the ceria surfaces for silicate adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Jihoon [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Moon, Jinok [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Clean/CMP Technology Team, Memory, Samsung Electronics, Hwaseong (Korea, Republic of); Kim, Joo Hyun; Lee, Kangchun [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Hwang, Junha [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Materials R& D Center, K.C.Tech, Anseong (Korea, Republic of); Yoon, Heesung [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Yi, Dong Kee, E-mail: vitalis@mju.ac.kr [Department of Chemistry, Myongji University, Yongin (Korea, Republic of); Paik, Ungyu, E-mail: upaik@hanyang.ac.kr [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of)

    2016-12-15

    Highlights: • We investigated the role of Ce oxidation state (Ce{sup 3+}/Ce{sup 4+}) on the CeO{sub 2} surfaces for the silicate adsorption. • As the Ce{sup 3+} concentration increased from 19.3 to 27.6%, the surface density of −OH group increased from 0.34 to 0.72 OH/nm{sup 2}. • The Freundlich constant for the relative adsorption capacity (K{sub F}) and adsorption intensity (1/n) indicated that CeO{sub 2} NPs with high Ce{sup 3+} concentration show higher adsorption affinity with silicate ions. - Abstract: In this study, we have investigated the role of the Ce oxidation state (Ce{sup 3+}/Ce{sup 4+}) on the CeO{sub 2} surfaces for silicate adsorption. In aqueous medium, the Ce{sup 3+} sites lead to the formation of −OH groups at the CeO{sub 2} surface through H{sub 2}O dissociation. Silicate ions can adsorb onto the CeO{sub 2} surface through interaction with the −OH groups (−Ce−OH− + −Si−O{sup −} ↔ −Ce−O−Si− + OH{sup −}). As the Ce{sup 3+} concentration increased from 19.3 to 27.6%, the surface density of −OH group increased from 0.34 to 0.72 OH/nm{sup 2}. To evaluate the adsorption behaviors of silicate ions onto CeO{sub 2} NPs, we carried out an adsorption isothermal analysis, and the adsorption isotherm data followed the Freundlich model. The Freundlich constant for the relative adsorption capacity (K{sub F}) and adsorption intensity (1/n) indicated that CeO{sub 2} NPs with high Ce{sup 3+} concentration show higher adsorption affinity with silicate ions. As a result, we have demonstrated that the Ce oxidation state (Ce{sup 3+}/Ce{sup 4+}) on the CeO{sub 2} surface can have a significant influence on the silicate adsorption.

  4. Electronic state of ruthenium deposited onto oxide supports: An XPS study taking into account the final state effects

    International Nuclear Information System (INIS)

    Larichev, Yurii V.; Moroz, Boris L.; Bukhtiyarov, Valerii I.

    2011-01-01

    The electronic state of ruthenium in the supported Ru/EO x (EO x = MgO, Al 2 O 3 or SiO 2 ) catalysts prepared by with the use of Ru(OH)Cl 3 or Ru(acac) 3 (acac = acetylacetonate) and reduced with H 2 at 723 K is characterized by X-ray photoelectron spectroscopy (XPS) in the Ru 3d, Cl 2p and O 1s regions. The influence of the final state effects (the differential charging and variation of the relaxation energy) on the binding energy (BE) of Ru 3d 5/2 core level measured for supported Ru nanoparticles is estimated by comparison of the Fermi levels and the modified Auger parameters determined for the Ru/EO x samples with the corresponding characteristics of the bulk Ru metal. It is found that the negative shift of the Ru 3d 5/2 peak which is observed in the spectrum of ruthenium deposited onto MgO (BE = 279.5-279.7 eV) with respect to that of Ru black (BE = 280.2 eV) or ruthenium supported on γ-Al 2 O 3 and SiO 2 (BE = 280.4 eV) is caused not by the transfer of electron density from basic sites of MgO, as considered earlier, but by the differential charging of the supported Ru particles compared with the support surface. Correction for the differential charging value reveals that the initial state energies of ruthenium in the Ru/EO x systems are almost identical (BE = 280.5 ± 0.1 eV) irrespectively of acid-base properties of the support, the mean size of supported Ru crystallites (within the range of 2-10 nm) and the surface Cl content. The results obtained suggest that the difference in ammonia synthesis activity between the Ru catalysts supported on MgO and on the acidic supports is accounted for by not different electronic state of ruthenium on the surface of these oxides but by some other reasons.

  5. The Young Solar Analogs Project

    Science.gov (United States)

    Gray, Richard O.; Saken, J. M.; Corbally, C. J.; Fuller, V.; Kahvaz, Y.; Lambert, R.; Newsome, I.; Seeds, M.

    2013-01-01

    We are carrying out a long-term project of measuring chromospheric activity and brightness variations in 31 young solar analogs (YSAs) using facilities at the Dark Sky Observatory (DSO - Appalachian State University) and the Vatican Advanced Technology Telescope (VATT). These YSAs are solar-type (spectral types F8 - K2) stars with ages ranging from 0.3 - 1.5 Gyr. The goal of this project is to gain better understanding of the magnetic activity of the early Sun, and especially how that activity may have impacted the development of life on the Earth. This project will also yield insights into the space environments experienced by young Earth analogs. We are currently in the 6th year of spectroscopic measurements of these stars: these data include Ca II H & K chromospheric flux measurements, and narrow-band measurements in the photospheric G-band, both obtained with the G/M spectrograph on the DSO 32-inch telescope. We will present evidence of activity cycles in a number of our stars, as well as periods determined from rotational modulation of the spectroscopic indices. The relationship between the Ca II activity index and the G-band index will be explored. NSF support for our project has provided funds for the construction of a robotic photometric telescope to monitor the program stars in a 5-passband system (Strömgren-v, Johnson-Cousins B, V, and R, and a 3-nm wide Hα filter). The robotic telescope has been functional since April 2012 and observes the program stars on every clear night; combined with the Piggy-back telescope attached to the DSO 32-inch, we now have photometric observations on over 130 nights stretching over nearly 2 years. We will examine the relationships between variations in the Ca II H & K index, the G-band index and the photometric bands. This project is supported by the National Science Foundation, grant AST-1109158.

  6. The Young Solar Analogs Project

    Science.gov (United States)

    Gray, Richard O.; Saken, J. M.; Corbally, C. J.; Seeds, M. F.; Morrison, S. S.

    2012-01-01

    We are carrying out a long-term project of measuring chromospheric activity and brightness variations in 31 young solar analogs (YSAs) using the Dark Sky Observatory (DSO -- Appalachian State University) 32-inch telescope and the G/M spectrograph. These YSAs are solar-type (spectral types F8 - K2) stars with ages ranging from 0.3 - 1.5 Gyr. The goal of this project is to gain better understanding of the magnetic activity of the early Sun, and especially how that activity may have impacted the development of life on the Earth. This project will also yield insights into the space environments experienced by young Earth analogs. We are currently in our 5th year of obtaining Ca II K & H chromospheric flux measurements, and are beginning to see signs of long-term activity cycles in a number of our stars. In addition, rotational modulation of the chromospheric fluxes is detectable in our data, and we have determined rotational periods for many of our stars. Short timescale increases in the K & H fluxes have been observed in a number of our stars; these events may be related to stellar flares. VATTSpec, a new moderate-resolution spectrograph on the 1.8-m Vatican Telescope in Arizona, has recently become involved with the project. This spectrograph will increase our ability to detect short-term changes in stellar activity on timescales of hours to minutes. We have been monitoring the program stars for one year in a multi-band photometric system consisting of Stromgren-v, and Johnson B, V, and R filters. We will soon add a narrow-band H-alpha filter to the system. Photometry is being carried out with a small piggy-back telescope on the 32-inch, but a robotic photometric telescope is currently being installed at DSO for this purpose. This project is supported by the National Science Foundation.

  7. Prototype of IGZO-TFT preamplifier and analog counter for pixel detector

    International Nuclear Information System (INIS)

    Shimazoe, K.; Koyama, A.; Takahashi, H.; Shindoh, T.; Miyoshi, H.

    2017-01-01

    IGZO-TFT (Indium Galium Zinc Oxide-Thin Film Transistor) is a promising technology for controlling large display areas and large area sensors because of its very low leakage current in the off state and relatively low cost. IGZO has been used as a switching gate for a large area flat-panel detector. The photon counting capability for X-ray medical imaging has been investigated and expected for low-dose exposure and material determination. Here the design and fabrication of a charge sensitive preamplifier and analog counter using IGZO-TFT processes and its performance are reported for the first time to be used for radiation photon counting applications.

  8. Solid-state ionics: Studies of lithium-conducting sulfide glasses and a superconducting oxide compound

    International Nuclear Information System (INIS)

    Ahn, Byung Tae.

    1989-01-01

    The first part of this work studies lithium-conducting sulfide glasses for battery applications, while the second part studies the thermodynamic properties of a superconducting oxide compound by using an oxide electrolyte. Lithium conducting glasses based on the SiS 2 -Li 2 S system are possible solid electrolytes for high-energy-density lithium batteries. The foremost requirement for solid electrolytes is that they should have high ionic conductivities. Unfortunately, most crystalline lithium conductors have low ionic conductivities at room temperature. However, glass ionic conductors show higher ionic conductivities than do crystalline forms of the same material. In addition to higher ionic conductivities, glasses appear to have several advantages over crystalline materials. These advantages include isotropic conductivity, absence of grain boundary effects, ease of glass forming, and the potential for a wide range of stability to oxidizing and reducing conditions. Using pyrolitic graphite-coated quartz ampoules, new ternary compounds and glasses in the SiS 2 -Li 2 S system were prepared. Several techniques were used to characterize the materials: powder x-ray diffraction, differential thermal analysis, differential scanning calorimetry, and AC impedance spectroscopy. The measured lithium conductivity of the sulfide glasses was one of the highest among the known solid lithium conductors. Measuring the equilibrium open circuit voltages assisted in determining the electrochemical stabilities of the ternary compounds and glasses with respect to pure Li. A solid-state ionic technique called oxygen coulometric titration was used to measure the thermodynamic stability, the oxygen stoichiometry, and the effects of the oxygen stoichiometry, and the effects of the oxygen stoichiometry and the cooling rate on superconductivity of the YBa 2 Cu 3 O 7-x compound were investigated

  9. Effect of charge state and stoichiometry on the structure and reactivity of nickel oxide clusters with CO

    Science.gov (United States)

    Johnson, Grant E.; Reilly, Nelly M.; Castleman, A. W., Jr.

    2009-02-01

    The collision induced fragmentation and reactivity of cationic and anionic nickel oxide clusters with carbon monoxide were studied experimentally using guided-ion-beam mass spectrometry. Anionic clusters with a stoichiometry containing one more oxygen atom than nickel atom (NiO2-, Ni2O3-, Ni3O4- and Ni4O5-) were found to exhibit dominant products resulting from the transfer of a single oxygen atom to CO, suggesting the formation of CO2. Of these four species, Ni2O3- and Ni4O5- were observed to be the most reactive having oxygen transfer products accounting for approximately 5% and 10% of the total ion intensity at a maximum pressure of 15 mTorr of CO. Our findings, therefore, indicate that anionic nickel oxide clusters containing an even number of nickel atoms and an odd number of oxygen atoms are more reactive than those with an odd number of nickel atoms and an even number of oxygen atoms. The majority of cationic nickel oxides, in contrast to anionic species, reacted preferentially through the adsorption of CO onto the cluster accompanied by the loss of either molecular O2 or nickel oxide units. The adsorption of CO onto positively charged nickel oxides, therefore, is exothermic enough to break apart the gas-phase clusters. Collision induced dissociation experiments, employing inert xenon gas, were also conducted to gain insight into the structural properties of nickel oxide clusters. The fragmentation products were found to vary considerably with size and stoichiometry as well as ionic charge state. In general, cationic clusters favored the collisional loss of molecular O2 while anionic clusters fragmented through the loss of both atomic oxygen and nickel oxide units. Our results provide insight into the effect of ionic charge state on the structure of nickel oxide clusters. Furthermore, we establish how the size and stoichiometry of nickel oxide clusters influences their ability to oxidize CO, an important reaction for environmental pollution abatement.

  10. Beginning analog electronics through projects

    CERN Document Server

    Singmin, Andrew

    2001-01-01

    Analog electronics is the simplest way to start a fun, informative, learning program. Beginning Analog Electronics Through Projects, Second Edition was written with the needs of beginning hobbyists and students in mind. This revision of Andrew Singmin's popular Beginning Electronics Through Projects provides practical exercises, building techniques, and ideas for useful electronics projects. Additionally, it features new material on analog and digital electronics, and new projects for troubleshooting test equipment.Published in the tradition of Beginning Electronics Through Projects an

  11. Remote Sensing the Thermosphere's State Using Emissions From Carbon Dioxide and Nitric Oxide

    Science.gov (United States)

    Weimer, D. R.; Mlynczak, M. G.; Doornbos, E.

    2017-12-01

    Measurements of emissions from nitric oxide and carbon dioxide in the thermosphere have strong correlations with properties that are very useful to the determination of thermospheric densities. We have compared emissions measured with the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite with neutral density measurements from the Challenging Mini-satellite Payload (CHAMP), the Gravity Recovery and Climate Experiment (GRACE), the Ocean Circulation Explorer (GOCE), and the three Swarm satellites, spanning a time period of over 15 years. It has been found that nitric oxide emissions match changes in the exospheric temperatures that have been derived from the densities through use of the Naval Reasearch Laboratory Mass Spectrometer, Incoherent Scatter Radar Extended Model (NRLMSISE-00) thermosphere model. Similarly, our results indicate that the carbon dioxide emissions have annual and semiannual oscillations that correlate with changes in the amount of oxygen in the thermosphere, also determined by use of the NRLMSISE-00 model. These annual and semi-annual variations are found to have irregular amplitudes and phases, which make them very difficult to accurately predict. Prediction of exospheric temperatures through the use of geomagnetic indices also tends to be inexact. Therefore, it would be possible and very useful to use measurements of the thermosphere's infrared emissions for real-time tracking of the thermosphere's state, so that more accurate calculations of the density may be obtained.

  12. Solid State Energy Conversion Alliance (SECA) Solid Oxide Fuel Cell Program

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Minh

    2006-07-31

    This report summarizes the work performed for Phase I (October 2001 - August 2006) under Cooperative Agreement DE-FC26-01NT41245 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled 'Solid State Energy Conversion Alliance (SECA) Solid Oxide Fuel Cell Program'. The program focuses on the development of a low-cost, high-performance 3-to-10-kW solid oxide fuel cell (SOFC) system suitable for a broad spectrum of power-generation applications. During Phase I of the program significant progress has been made in the area of SOFC technology. A high-efficiency low-cost system was designed and supporting technology developed such as fuel processing, controls, thermal management, and power electronics. Phase I culminated in the successful demonstration of a prototype system that achieved a peak efficiency of 41%, a high-volume cost of $724/kW, a peak power of 5.4 kW, and a degradation rate of 1.8% per 500 hours. . An improved prototype system was designed, assembled, and delivered to DOE/NETL at the end of the program. This prototype achieved an extraordinary peak efficiency of 49.6%.

  13. Determination of oxidation state of iron in normal and pathologically altered human aortic valves

    Energy Technology Data Exchange (ETDEWEB)

    Czapla-Masztafiak, J. [Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342 Kraków (Poland); Lis, G.J.; Gajda, M.; Jasek, E. [Department of Histology, Jagiellonian University Medical College, Kopernika 7, 31-034 Kraków (Poland); Czubek, U. [Department of Coronary Disease, Jagiellonian University Medical College, John Paul II Hospital, Prądnicka 80, 31-202 Kraków (Poland); Bolechała, F. [Department of Forensic Medicine, Jagiellonian University Medical College, Grzegórzecka 16, 31-531 Kraków (Poland); Borca, C. [Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Kwiatek, W.M. [Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342 Kraków (Poland)

    2015-12-01

    In order to investigate changes in chemical state of iron in normal and pathologically altered human aortic valves X-ray absorption spectroscopy was applied. Since Fe is suspected to play detrimental role in aortic valve stenosis pathogenesis the oxidation state of this element has been determined. The experimental material consisted of 10 μm sections of valves excised during routine surgery and from autopsies. The experiment was performed at the MicroXAS beamline of the SLS synchrotron facility in Villigen (Switzerland). The Fe K-edge XANES spectra obtained from tissue samples were carefully analyzed and compared with the spectra of reference compounds containing iron in various chemical structures. The analysis of absorption edge position and shape of the spectra revealed that both chemical forms of iron are presented in valve tissue but Fe{sup 3+} is the predominant form. Small shift of the absorption edge toward higher energy in the spectra from stenotic valve samples indicates higher content of the Fe{sup 3+} form in pathological tissue. Such a phenomenon suggests the role of Fenton reaction and reactive oxygen species in the etiology of aortic valve stenosis. The comparison of pre-edge regions of XANES spectra for control and stenotic valve tissue confirmed no differences in local symmetry or spin state of iron in analyzed samples.

  14. The effect of cerium valence states at cerium oxide nanoparticle surfaces on cell proliferation

    KAUST Repository

    Naganuma, Tamaki

    2014-05-01

    Understanding and controlling cell proliferation on biomaterial surfaces is critical for scaffold/artificial-niche design in tissue engineering. The mechanism by which underlying integrin ligates with functionalized biomaterials to induce cell proliferation is still not completely understood. In this study, poly-l-lactide (PL) scaffold surfaces were functionalized using layers of cerium oxide nanoparticles (CNPs), which have recently attracted attention for use in therapeutic application due to their catalytic ability of Ce4+ and Ce3+ sites. To isolate the influence of Ce valance states of CNPs on cell proliferation, human mesenchymal stem cells (hMSCs) and osteoblast-like cells (MG63) were cultured on the PL/CNP surfaces with dominant Ce4+ and Ce3+ regions. Despite cell type (hMSCs and MG63 cells), different surface features of Ce4+ and Ce3+ regions clearly promoted and inhibited cell spreading, migration and adhesion behavior, resulting in rapid and slow cell proliferation, respectively. Cell proliferation results of various modified CNPs with different surface charge and hydrophobicity/hydrophilicity, indicate that Ce valence states closely correlated with the specific cell morphologies and cell-material interactions that trigger cell proliferation. This finding suggests that the cell-material interactions, which influence cell proliferation, may be controlled by introduction of metal elements with different valence states onto the biomaterial surface. © 2014 Elsevier Ltd.

  15. Investigating the capability of ToF-SIMS to determine the oxidation state of Ce

    Science.gov (United States)

    Seed Ahmed, H. A. A.; Swart, H. C.; Kroon, R. E.

    2018-04-01

    The capability of time of flight secondary ion mass spectrometry (ToF-SIMS) to determine the oxidation state of Ce ions doped in a phosphor was investigated. Two samples of SiO2:Ce (4 mol%) with known Ce3+/Ce4+ relative concentrations were subjected to ToF-SIMS measurements. The spectra were very similar and no significant differences in the relative peak intensities were observed that would readily allow one to distinguish Ce3+ from Ce4+. Although ToF-SIMS was therefore not useful to distinguish the charge state of Ce ions doped in this phosphor material, the idea in principle was also tested on two other samples, namely CeF3 and CeF4 These contain Ce as part of the host (i.e. much higher concentration) and are fluorides, which is significant because ToF-SIMS has previously been reported to be able to distinguish Eu2+ from Eu3+ in Eu doped Sr5(PO4)3F phosphor. The spectrum of CeF4 contained a small peak related to Ce4+ which was not observed in the CeF3 spectrum, yet the peak related to the Ce3+ ions was found to be much more intense in the spectrum of CeF4 than CeF3, showing that the ToF-SIMS signals cannot be directly interpreted as retaining the charge state of the ions in the original material. Nevertheless, the significant differences in the Ce-related peaks in the ToF-SIMS spectra from CeF3 and CeF4 show that the charge state of Ce may be distinguished. This study shows that while in principle ToF-SIMS may be used to distinguish the charge state of Ce ions, this depends on the sample and it would not be easy to interpret the spectra without a standard or reference.

  16. Coherent diffractive imaging of solid state reactions in zinc oxide crystals

    Science.gov (United States)

    Leake, Steven J.; Harder, Ross; Robinson, Ian K.

    2011-11-01

    We investigated the doping of zinc oxide (ZnO) microcrystals with iron and nickel via in situ coherent x-ray diffractive imaging (CXDI) in vacuum. Evaporated thin metal films were deposited onto the ZnO microcrystals. A single crystal was selected and tracked through annealing cycles. A solid state reaction was observed in both iron and nickel experiments using CXDI. A combination of the shrink wrap and guided hybrid-input-output phasing methods were applied to retrieve the electron density. The resolution was 33 nm (half order) determined via the phase retrieval transfer function. The resulting images are nevertheless sensitive to sub-angstrom displacements. The exterior of the microcrystal was found to degrade dramatically. The annealing of ZnO microcrystals coated with metal thin films proved an unsuitable doping method. In addition the observed defect structure of one crystal was attributed to the presence of an array of defects and was found to change upon annealing.

  17. Oxidation-state distribution of plutonium in surface and subsurface waters at Thule, northwest Greenland

    DEFF Research Database (Denmark)

    McMahon, C.A.; Vintró, L.L.; Mitchell, P.I.

    2000-01-01

    (V, VI) (mean, 68 +/- 6%; n = 6), with little if any distinction apparent between surface and bottom waters. Further, the oxidation state distribution at stations close to the accident site is similar to that measured at Upernavik, remote from this site. It is also similar to the distribution observed...... in shelf waters at midlatitudes, suggesting that the underlying processes controlling plutonium speciation are insensitive to temperature over the range 0-25 degrees C. Measurements using tangential-flow ultrafiltration indicate that virtually all of the plutonium (including the fraction in a reduced...... chemical form) is present as fully dissolved species. Most of this plutonium would seem to be of weapons fallout origin, as the mean Pu-238/Pu-239,Pu-240 activity ratio in the water column (dissolved phase) at Thule (0.06 +/- 0.02; n = 10) is similar to the global fallout ratio at this latitude...

  18. State-of-the-art technologies of gallium oxide power devices

    Science.gov (United States)

    Higashiwaki, Masataka; Kuramata, Akito; Murakami, Hisashi; Kumagai, Yoshinao

    2017-08-01

    Gallium oxide (Ga2 O3 ) has gained increased attention for power devices due to its superior material properties and the availability of economical device-quality native substrates. This review illustrates recent advances in Ga2 O3 device technologies, beginning with an overview of the social circumstances that motivate the development of new-generation switching devices. Following an introduction to the material properties of Ga2 O3 from the viewpoint of power electronics, growth technologies of Ga2 O3 bulk single crystals and epitaxial thin films are discussed. The fabrication and performance of state-of-the-art Ga2 O3 transistors and diodes are then described. We conclude by identifying the directions and challenges of Ga2 O3 power device development in the near future.

  19. Coordination and Oxidation States of Iron Incorporated in Mesoporous MCM41

    International Nuclear Information System (INIS)

    Lazar, K.; Pal-Borbely, G.; Szegedi, A.; Beyer, H. K.

    2002-01-01

    Mesoporous Fe-MCM41 samples (Si/Fe=25) were synthesized and characterized under evacuation and reducing/oxidizing treatments by in situ FTIR and Moessbauer spectroscopies. Both Fe(II) and Fe(III) located in low coordination states in top layers of pore walls exhibit Lewis acidity and may participate in Fe(III) ↔ Fe(II) processes at low temperatures (570 K). Furthermore, Fe(III) ↔ Fe(II) cycles can be achieved and repeated with participation of the full amount of iron at higher temperatures (670 K). The accompanying formation of oxygen vacancies and restoration of the structure in the reverse process does not result in extended damages; the MCM41 structure retains its stability under the conditions applied.

  20. Children's Development of Analogical Reasoning: Insights from Scene Analogy Problems

    Science.gov (United States)

    Richland, Lindsey E.; Morrison, Robert G.; Holyoak, Keith J.

    2006-01-01

    We explored how relational complexity and featural distraction, as varied in scene analogy problems, affect children's analogical reasoning performance. Results with 3- and 4-year-olds, 6- and 7-year-olds, 9- to 11-year-olds, and 13- and 14-year-olds indicate that when children can identify the critical structural relations in a scene analogy…

  1. Detection of different oxidation states of individual manganese porphyrins during their reaction with oxygen at a solid/liquid interface.

    Science.gov (United States)

    den Boer, Duncan; Li, Min; Habets, Thomas; Iavicoli, Patrizia; Rowan, Alan E; Nolte, Roeland J M; Speller, Sylvia; Amabilino, David B; De Feyter, Steven; Elemans, Johannes A A W

    2013-07-01

    Manganese porphyrins have been extensively investigated as model systems for the natural enzyme cytochrome P450 and as synthetic oxidation catalysts. Here, we report single-molecule studies of the multistep reaction of manganese porphyrins with molecular oxygen at a solid/liquid interface, using a scanning tunnelling microscope (STM) under environmental control. The high lateral resolution of the STM, in combination with its sensitivity to subtle differences in the electronic properties of molecules, allowed the detection of at least four distinct reaction species. Real-space and real-time imaging of reaction dynamics enabled the observation of active sites, immobile on the experimental timescale. Conversions between the different species could be tuned by the composition of the atmosphere (argon, air or oxygen) and the surface bias voltage. By means of extensive comparison of the results to those obtained by analogous solution-based chemistry, we assigned the observed species to the starting compound, reaction intermediates and products.

  2. Oxidation State of Iron in the Izu-Bonin Arc Initial Magma and Its Influence Factors

    Science.gov (United States)

    Li, H.; Arculus, R. J.; Brandl, P. A.; Hamada, M.; Savov, I. P.; Zhu, S.; Hickey-Vargas, R.; Tepley, F. J., III; Meffre, S.; Yogodzinski, G. M.; McCarthy, A.; Barth, A. P.; Kanayama, K.; Kusano, Y.; Sun, W.

    2014-12-01

    The redox state of mantle-derived magmas is a controversial issue, especially whether island arc basalts are more oxidized than those from mid-ocean ridges. Usually, arc magmas have higher Fe3+/Fe2+ and calculated oxygen fugacity (fO2) than mid-ocean ridge basalts (MORB). It is the high fO2 of arc magma that apparently delays onset of sulfide fractionation and sequestration of precious/base metals thereby facilitating the formation of many giant gold-copper deposits typically associated with subduction zones. But due to a paucity of Fe3+/Fe2+ data for primary mantle-derived arc magmas, the cause for high fO2 of these magma types is still controversial; causes may include inter alia subduction-released oxidized material addition to the mantle wedge source of arc magma, partial melting of subducted slab, and redox changes occurring during ascent of the magma. Fortunately, IODP expedition 351 drilling at IODP Site U1438 in the Amami-Sankaku Basin of the northwestern Philipine Sea, adjacent to the proto-Izu-Bonin Arc at the Kyushu-Palau Ridge (KPR), recovered not only volcaniclastics derived from the inception of Izu-Bonin Mariana (IBM) arc in the Eocene, but also similar materials for the Arc's subsequent evolution through to the Late Oligocene and abandonment of the KPR as a remnant arc. Samples of the pre-Arc oceanic crustal basement were also recovered enabling us to determine the fO2of the mantle preceding arc inception. As the oxidation state of iron in basaltic glass directly relates to the fO2 , the Fe3+/∑Fe ratio [Fe3+/(Fe3++ Fe2+)] of basaltic glass are quantified by synchrotron-facilitated micro X-ray Absorption Near Edge Structure (XANES) spectroscopy to reflect its fO2. Fe K-edge µ-XANES spectra were recorded in fluorescence mode at Beamline 15U1, Shanghai Synchrotron Radiation Facility (SSRF). Synthetic silicate glass with known Fe3+/∑Fe ratio was used in data handling. The experimental results as well as preliminary data from IODP Expedition 351

  3. Development of analog watch with minute repeater

    Science.gov (United States)

    Okigami, Tomio; Aoyama, Shigeru; Osa, Takashi; Igarashi, Kiyotaka; Ikegami, Tomomi

    A complementary metal oxide semiconductor with large scale integration was developed for an electronic minute repeater. It is equipped with the synthetic struck sound circuit to generate natural struck sound necessary for the minute repeater. This circuit consists of an envelope curve drawing circuit, frequency mixer, polyphonic mixer, and booster circuit made by using analog circuit technology. This large scale integration is a single chip microcomputer with motor drivers and input ports in addition to the synthetic struck sound circuit, and it is possible to make an electronic system of minute repeater at a very low cost in comparison with the conventional type.

  4. The oxidation state of Fe in glasses from the Kerguelen Large Igneous Province: Evidence for the changing oxidation state of the Indian Ocean Basin

    Science.gov (United States)

    Peterson, M. E.; Stolper, E.; Brounce, M. N.; Eiler, J. M.; Wallace, P. J.

    2017-12-01

    Oxygen fugacity (ƒO2) is a thermodynamic property of silicate magmas that can be influenced by volcanic processes such as melting, crystal fractionation, and degassing. Lavas erupted as part of large igneous provinces (LIPs) may reflect the impingement of mantle plumes on the lithosphere, and thus could provide constraints on the ƒO2 of plumes responsible for generation of LIPs. The Kerguelen plateau was emplaced during the break up of Gondwana and the initial opening of the Indian Ocean. Elevated 207Pb/204Pb and 208Pb/204Pb ratios at low 206Pb/204Pb suggests that continental lithosphere from Gondwana is present in the asthenosphere of this region. The Sr-Nd-Pb-He isotopic compositions of the Kerguelen lavas are variable and have been used to infer that the mantle sources of these lavas reflect contributions from the depleted upper mantle, a common plume component, and the EM1 mantle component (perhaps recycled lower continental crust; e.g. Frey et al., 2002). The ƒO2 of the lavas of the Kerguelen LIP may thus reflect mixing of the upper mantle (i.e., near QFM), the plume component, and continental crust. We present new μ-XANES measurements of Fe3+/ΣFe ratios in a suite of 21 submarine glasses from Kerguelen. Over a narrow range in MgO (6.5-7.5 wt%), these glasses have Fe3+/ΣFe ratios of 0.16-0.18, corresponding to an ƒO2 of QFM+0.23 to +0.38 (at 1 atm, 1200°C). The H2O/Ce and Cl/K ratios of these glasses suggest that they did not assimilate significant amounts of altered oceanic crust. Also, S-FeOT variations indicate that the magmas are near sulfide saturation. These lavas were erupted in 1000 m of water, precluding significant loss of S to a vapor phase. At a given MgO content, samples from Kerguelen have similar to higher Fe3+/ΣFe ratios than the average values found in samples from along the Indian mid-ocean ridge, which could indicate a more oxidized mantle source. In addition, increases in Fe3+/ΣFe ratios of the Kerguelen samples, over a narrow

  5. Optical analog transmission device

    International Nuclear Information System (INIS)

    Ikawa, Shinji.

    1994-01-01

    The present invention concerns a device such as electro-optical conversion elements, optoelectric-electric elements and optical transmission channel, not undergoing deleterious effects on the efficiency of conversion and transmission due to temperature, and aging change. That is, a sine wave superposing means superposes, on a detector signal to be transmitted, a sine-wave signal having a predetermined amplitude and at a frequency lower than that of the detector signal. An optoelectric conversion means converts the electric signal as the signal of the sine-wave signal superposing means into an optical signal and outputs the same to an optical transmitting channel. The optoelectric conversion means converts the transmitted signal to an electric signal. A discriminating means discriminates the electric signal into a detector signal and a sine-wave signal. A calculating means calculates an optical transmitting efficiency of the transmitting channel based on the amplitude of the discriminated sine-wave signal. A processing means compensates an amplitude value of the detector signals discriminated by the discriminating means based on the optical transmission efficiency. As a result, an optical analog transmission device can be attained, which conducts optical transmission at a high accuracy without undergoing the defective effects of the optical transmission efficiency. (I.S.)

  6. Ultrathin reduced graphene oxide films as transparent top-contacts for light switchable solid-state molecular junctions

    DEFF Research Database (Denmark)

    Li, Tao; Jevric, Martyn; Hauptmann, Jonas Rahlf

    2013-01-01

    A new type of solid-state molecular junction is introduced, which employs reduced graphene oxide as a transparent top contact that permits a self-assembled molecular monolayer to be photoswitched in situ, while simultaneously enabling charge-transport measurements across the molecules. The electr......A new type of solid-state molecular junction is introduced, which employs reduced graphene oxide as a transparent top contact that permits a self-assembled molecular monolayer to be photoswitched in situ, while simultaneously enabling charge-transport measurements across the molecules...

  7. Reactivity of biogenic manganese oxide for metal sequestration and photochemistry: Computational solid state physics study

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, K.D.; Sposito, G.

    2010-02-01

    Many microbes, including both bacteria and fungi, produce manganese (Mn) oxides by oxidizing soluble Mn(II) to form insoluble Mn(IV) oxide minerals, a kinetically much faster process than abiotic oxidation. These biogenic Mn oxides drive the Mn cycle, coupling it with diverse biogeochemical cycles and determining the bioavailability of environmental contaminants, mainly through strong adsorption and redox reactions. This mini review introduces recent findings based on quantum mechanical density functional theory that reveal the detailed mechanisms of toxic metal adsorption at Mn oxide surfaces and the remarkable role of Mn vacancies in the photochemistry of these minerals.

  8. Conjecturing via Reconceived Classical Analogy

    Science.gov (United States)

    Lee, Kyeong-Hwa; Sriraman, Bharath

    2011-01-01

    Analogical reasoning is believed to be an efficient means of problem solving and construction of knowledge during the search for and the analysis of new mathematical objects. However, there is growing concern that despite everyday usage, learners are unable to transfer analogical reasoning to learning situations. This study aims at facilitating…

  9. Musik som analogi og metafor

    DEFF Research Database (Denmark)

    Bonde, Lars Ole

    2014-01-01

    Indeholder underkapitlerne: 2.5.1 Musik som analogi 2.5.2 Musik som metafor 2.5.3 Musikkens psykologiske funktioner - en taxonomi og metaforisk lytning til fire baroksatser......Indeholder underkapitlerne: 2.5.1 Musik som analogi 2.5.2 Musik som metafor 2.5.3 Musikkens psykologiske funktioner - en taxonomi og metaforisk lytning til fire baroksatser...

  10. Drawing Analogies in Environmental Education

    Science.gov (United States)

    Affifi, Ramsey

    2014-01-01

    Reconsidering the origin, process, and outcomes of analogy-making suggests practices for environmental educators who strive to disengage humans from the isolating illusions of dichotomizing frameworks. We can view analogies as outcomes of developmental processes within which human subjectivity is but an element, threading our sense of self back…

  11. Analog and digital dividers for mass spectrometers

    International Nuclear Information System (INIS)

    Osipov, A.K.

    1980-01-01

    Errors of four different types of stress dividers used in statical mass-spectrometers for determination of mass number by accelerating stress are analyzed. The simplest flowsheet of the analog divider comprises operation amplifier, in the chain of the negative feedback of which a multiplication device on differential cascade is switched- in. This analog divider has high sensitivity to temperature and high error approximately 5%. Application of the multiplier on differential cascade with normalization permits to increase temperature stability and decrease the error up to 1%. Another type of the analog divider is a logarithmic divider the error of which is constant within the whole operation range and it constitutes 1-5%. The digital divider with a digital-analog transformer (DAT) has the error of +-0.015% which is determined by the error of detectors and resistance of keys in the locked state. Considered is the design of a divider based on transformation of the inlet stress into the time period. The error of the divider is determined in this case mainly by stress of the zero shift of the operation amplifier (it should be compensated) and relative threshold stability of the comparator triggering which equals (2-3)x10 -4 . It is noted that the divider with DAT application and the divider with the use of stress transformation within the time period are most perspective ones for statical mass-spectrometers [ru

  12. Insulin analogs with improved pharmacokinetic profiles.

    Science.gov (United States)

    Brange; Vølund

    1999-02-01

    The aim of insulin replacement therapy is to normalize blood glucose in order to reduce the complications of diabetes. The pharmacokinetics of the traditional insulin preparations, however, do not match the profiles of physiological insulin secretion. The introduction of the rDNA technology 20 years ago opened new ways to create insulin analogs with altered properties. Fast-acting analogs are based on the idea that an insulin with less tendency to self-association than human insulin would be more readily absorbed into the systemic circulation. Protracted-acting analogs have been created to mimic the slow, steady rate of insulin secretion in the fasting state. The present paper provides a historical review of the efforts to change the physicochemical and pharmacological properties of insulin in order to improve insulin therapy. The available clinical studies of the new insulins are surveyed and show, together with modeling results, that new strategies for optimal basal-bolus treatment are required for utilization of the new fast-acting analogs.

  13. Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

    Energy Technology Data Exchange (ETDEWEB)

    Hashemi, Mohammed M.; Eftekhari-Sis, Bagher; Khalili, Behzad; Karimi-Jaberi, Zahed [Sharif University of Technology, Tehran (Iran, Islamic Republic of). Dept. of Chemistry]. E-mail: mhashemi@sharif.edu

    2005-09-15

    Phenols were oxidized to quinones using sodium perborate (SPB) on wet montmorillonite as oxidant. The reaction was carried out at ambient temperature on the solid phase under solvent free conditions. (author)

  14. Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

    International Nuclear Information System (INIS)

    Hashemi, Mohammed M.; Eftekhari-Sis, Bagher; Khalili, Behzad; Karimi-Jaberi, Zahed

    2005-01-01

    Phenols were oxidized to quinones using sodium perborate (SPB) on wet montmorillonite as oxidant. The reaction was carried out at ambient temperature on the solid phase under solvent free conditions. (author)

  15. Oxidation of an aluminium-magnesium alloy in liquid state. Methodology of determination of mechanisms from not necessarily repeatable experiments

    International Nuclear Information System (INIS)

    Surla, Karine

    1998-01-01

    This research thesis reports the study of the oxidation of an aluminium-5 pc magnesium alloy in its liquid state in an oxygen environment, using thermogravimetric analysis and that of magnesium in its solid state. In a first part, the author reports a thermodynamic and bibliographical study on magnesium transformation in its solid state (Mg/O 2 and Mg/H 2 O systems, transformation with dry and humid synthetic air, oxidation inhibitors) and on Al-Mg alloy transformation in presence of oxygen (thermodynamic properties of aluminium-rich Al-Mg alloys, Al-Mg/O 2 /N 2 and Al-Mg/O 2 /N 2 /H 2 O systems). The next parts address the selection of reaction systems for the different cases (oxidation of solid magnesium in oxygen, oxidation of the Al-Mg alloy in oxygen), the modelling of the formation of magnesia from solid magnesium and from the Al-Mg alloy, and the modelling of the liquid Al-Mg A5182 alloy oxidation in oxygen [fr

  16. Hydrophobic matrix-free graphene-oxide composites with isotropic and nematic states

    Science.gov (United States)

    Wåhlander, Martin; Nilsson, Fritjof; Carlmark, Anna; Gedde, Ulf W.; Edmondson, Steve; Malmström, Eva

    2016-08-01

    We demonstrate a novel route to synthesise hydrophobic matrix-free composites of polymer-grafted graphene oxide (GO) showing isotropic or nematic alignment and shape-memory effects. For the first time, a cationic macroinitiator (MI) has been immobilised on anionic GO and subsequently grafted with hydrophobic polymer grafts. Dense grafts of PBA, PBMA and PMMA with a wide range of average graft lengths (MW: 1-440 kDa) were polymerised by surface-initiated controlled radical precipitation polymerisation from the statistical MI. The surface modification is designed similarly to bimodal graft systems, where the cationic MI generates nanoparticle repulsion, similar to dense short grafts, while the long grafts offer miscibility in non-polar environments and cohesion. The state-of-the-art dispersions of grafted GO were in the isotropic state. Transparent and translucent matrix-free GO-composites could be melt-processed directly using only grafted GO. After processing, birefringence due to nematic alignment of grafted GO was observed as a single giant Maltese cross, 3.4 cm across. Permeability models for composites containing aligned 2D-fillers were developed, which were compared with the experimental oxygen permeability data and found to be consistent with isotropic or nematic states. The storage modulus of the matrix-free GO-composites increased with GO content (50% increase at 0.67 wt%), while the significant increases in the thermal stability (up to 130 °C) and the glass transition temperature (up to 17 °C) were dependent on graft length. The tuneable matrix-free GO-composites with rapid thermo-responsive shape-memory effects are promising candidates for a vast range of applications, especially selective membranes and sensors.We demonstrate a novel route to synthesise hydrophobic matrix-free composites of polymer-grafted graphene oxide (GO) showing isotropic or nematic alignment and shape-memory effects. For the first time, a cationic macroinitiator (MI) has been

  17. The Effect of Precursor Ligands and Oxidation State in the Synthesis of Bimetallic Nano-Alloys

    KAUST Repository

    LaGrow, Alec P.

    2015-05-12

    The characteristics of bimetallic nanomaterials are dictated by their size, shape and elemental distribution. Solution synthesis is widely utilized to form nanomaterials, such as nanoparticles, with controlled size and shape. However, the effects of variables on the characteristics of bimetallic nanomaterials are not completely understood. In this study, we used a continuous-flow synthetic strategy to explore the effects of the ligands and the oxidation state of a metal precursor in a shape-controlled synthesis on the final shape of the nanomaterials and the elemental distribution within the alloy. We demonstrate that this strategy can tune the size of monodisperse PtM (M=Ni or Cu) alloy nanocrystals ranging from 3 to 16 nm with an octahedral shape using acetylacetonate or halide precursors of Pt(II), Pt(IV) and Ni or Cu (II). The nanoparticles formed from halide precursors showed an enrichment of platinum on their surfaces, and the bromides could oxidatively etch the nanoparticles during synthesis with the O2/Br- pair. The two nanocrystal precursors can be uti-lized independently and can control the size with a trend of Pt(acac)2

  18. A hierarchical spatiotemporal analog forecasting model for count data.

    Science.gov (United States)

    McDermott, Patrick L; Wikle, Christopher K; Millspaugh, Joshua

    2018-01-01

    Analog forecasting is a mechanism-free nonlinear method that forecasts a system forward in time by examining how past states deemed similar to the current state moved forward. Previous applications of analog forecasting has been successful at producing robust forecasts for a variety of ecological and physical processes, but it has typically been presented in an empirical or heuristic procedure, rather than as a formal statistical model. The methodology presented here extends the model-based analog method of McDermott and Wikle (Environmetrics, 27, 2016, 70) by placing analog forecasting within a fully hierarchical statistical framework that can accommodate count observations. Using a Bayesian approach, the hierarchical analog model is able to quantify rigorously the uncertainty associated with forecasts. Forecasting waterfowl settling patterns in the northwestern United States and Canada is conducted by applying the hierarchical analog model to a breeding population survey dataset. Sea surface temperature (SST) in the Pacific Ocean is used to help identify potential analogs for the waterfowl settling patterns.

  19. Electrochemical and spectroscopic studies of some less stable oxidation states of selected lanthanide and actinide elements

    International Nuclear Information System (INIS)

    Hobart, D.E.

    1981-06-01

    Simultaneous observation of electrochemical and spectroscopic properties (spectroelectrochemistry) at optically transparent electrodes (OTE's) was used to study some less stable oxidation states of selected lanthanide and actinide elements. Cyclic voltammetry at microelectrodes was used in conjunction with spectroelectrochemistry for the study of redox couples. Additional analytical techniques were used. The formal reduction potential (E 0 ') values of the M(III)/M(II) redox couples in 1 M KCl at pH 6 were -0.34 +- 0.01 V for Eu, -1.18 +- 0.01 V for Yb, and -1.50 +- 0.01 V for Sm. Spectropotentiostatic determination of E 0 ' for the Eu(III)/Eu(II) redox couple yielded a value of -0.391 +- 0.005 V. Spectropotentiostatic measurement of the Ce(IV)/Ce(III) redox couple in concentrated carbonate solution gave E 0 ' equal to 0.051 +- 0.005 V, which is about 1.7 V less positive than the E 0 ' value in noncomplexing solution. This same difference in potential was observed for the E 0 ' values of the Pr(IV)/Pr(III) and Tb(IV)/Tb(III) redox couples in carbonate solution, and thus Pr(IV) and Tb(IV) were stabilized in this medium. The U(VI)/U(V)/U(IV) and U(IV)/U(III) redox couples were studied in 1 M KCl at OTE's. Spectropotentiostatic measurement of the Np(VI)/Np(V) redox couple in 1 M HClO 4 gave an E 0 ' value of 1.140 +- 0.005 V. An E 0 ' value of 0.46 +- 0.01 V for the Np(VII)/Np(VI) couple was found by voltammetry. Oxidation of Am(III) was studied in concentrated carbonate solution, and a reversible cyclic voltammogram for the Am(IV)/Am(III) couple yielded E 0 ' = 0.92 +- 0.01 V in this medium; this value was used to estimate the standard reduction potential (E 0 ) of the couple as 2.62 +- 0.01 V. Attempts to oxidize Cm(III) in concentrated carbonate solution were not successful which suggests that the predicted E 0 value for the Cm(IV)/Cm(III) redox couple may be in error

  20. Associative memory in an analog iterated-map neural network

    Science.gov (United States)

    Marcus, C. M.; Waugh, F. R.; Westervelt, R. M.

    1990-03-01

    The behavior of an analog neural network with parallel dynamics is studied analytically and numerically for two associative-memory learning algorithms, the Hebb rule and the pseudoinverse rule. Phase diagrams in the parameter space of analog gain β and storage ratio α are presented. For both learning rules, the networks have large ``recall'' phases in which retrieval states exist and convergence to a fixed point is guaranteed by a global stability criterion. We also demonstrate numerically that using a reduced analog gain increases the probability of recall starting from a random initial state. This phenomenon is comparable to thermal annealing used to escape local minima but has the advantage of being deterministic, and therefore easily implemented in electronic hardware. Similarities and differences between analog neural networks and networks with two-state neurons at finite temperature are also discussed.

  1. The effect on phase separation of the oxidation state of molybdenum in a Na2O-B2O3-SiO2 glass

    International Nuclear Information System (INIS)

    Kawamoto, Y.; Clemens, K.; Tomozawa, M.; Warden, J.T.

    1981-01-01

    The effect of oxidation state on phase separation was studied for 13Na 2 O, 49B 2 O 3 , 38SiO 2 (mol%) glasses containing 1 mol% Mo oxide. The glasses were melted under various conditions to vary the oxidation states of Mo ions. The oxidation states of Mo ions were determined by chemical analysis and ESR. The crystallisation tendency, the immiscibility temperature, and the phase separation morphology of the glasses were examined by DTA, x-ray diffraction, opalescence method, and replica electron microscopy. Glasses containing Mo 4+ ions have a great tendency to precipitate MoO 2 crystals. The immiscibility temperature of glass goes through a minimum when the oxidation states of Mo ions are changed. It was suggested that there is an optimum oxidation state to prevent crystallisation and to suppress the phase separation tendency of this system. (author)

  2. Operando XAS Study of the Surface Oxidation State on a Monolayer IrOx on RuOx and Ru Oxide Based Nanoparticles for Oxygen Evolution in Acidic Media

    DEFF Research Database (Denmark)

    Pedersen, Anders Filsøe; Escribano, Maria Escudero; Sebok, Bela

    2018-01-01

    that the average Ir oxidation state change is strongly affected by the coverage of atomic O. The observed shifts in oxidation state suggest that the surface has a high coverage of O at potentials just below the potential where oxygen evolution is exergonic in free energy. This observation is consistent...

  3. Effect of high doses of L-ascorbic acid on the antioxidative/oxidative state in the rats

    DEFF Research Database (Denmark)

    Niemiec, T.; Sawosz, E.; Chwalibog, André

    2005-01-01

    The objective of this study was to determine the effects of mega-doses of vitamin C (0.3, 0.6 and 0.9% of diet) as a dietary supplement for rats on selected indices of the antioxidative/oxidative state in 40 growing Wistar rats (4x10). It was found that L-ascorbic acid and Total Antioxidative State...... (TAS) in plasma did not increase with increasing vitamin C supply. The results indicate that high doses of L-ascorbic acid (0.3 and 0.9 but not 0.6%) increased the concentration of this antioxidant in plasma. Supplementation of vitamin C above 0.3% to the diets had pro-oxidative effects on lipid...... structures, while application of 0.9% promoted oxidative degradation of rat livers....

  4. Heat Transfer Analogies

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, A

    1965-11-15

    This report contains descriptions of various analogues utilised to study different steady-state and unsteady-state heat transfer problems. The analogues covered are as follows: 1 . Hydraulic: a) water flow b) air flow 2. Membrane 3. Geometric Electrical: a) Electrolytic-tank b) Conducting sheet 4. Network; a) Resistance b) R-C A comparison of the different analogues is presented in the form of a table.

  5. Heat Transfer Analogies

    International Nuclear Information System (INIS)

    Bhattacharyya, A.

    1965-11-01

    This report contains descriptions of various analogues utilised to study different steady-state and unsteady-state heat transfer problems. The analogues covered are as follows: 1 . Hydraulic: a) water flow b) air flow 2. Membrane 3. Geometric Electrical: a) Electrolytic-tank b) Conducting sheet 4. Network; a) Resistance b) R-C A comparison of the different analogues is presented in the form of a table

  6. Analog-to-digital conversion

    CERN Document Server

    Pelgrom, Marcel J M

    2010-01-01

    The design of an analog-to-digital converter or digital-to-analog converter is one of the most fascinating tasks in micro-electronics. In a converter the analog world with all its intricacies meets the realm of the formal digital abstraction. Both disciplines must be understood for an optimum conversion solution. In a converter also system challenges meet technology opportunities. Modern systems rely on analog-to-digital converters as an essential part of the complex chain to access the physical world. And processors need the ultimate performance of digital-to-analog converters to present the results of their complex algorithms. The same progress in CMOS technology that enables these VLSI digital systems creates new challenges for analog-to-digital converters: lower signal swings, less power and variability issues. Last but not least, the analog-to-digital converter must follow the cost reduction trend. These changing boundary conditions require micro-electronics engineers to consider their design choices for...

  7. Analog fourier transform channelizer and OFDM receiver

    OpenAIRE

    2007-01-01

    An OFDM receiver having an analog multiplier based I-Q channelizing filter, samples and holds consecutive analog I-Q samples of an I-Q baseband, the I-Q basebands having OFDM sub-channels. A lattice of analog I-Q multipliers and analog I-Q summers concurrently receives the held analog I-Q samples, performs analog I-Q multiplications and analog I-Q additions to concurrently generate a plurality of analog I-Q output signals, representing an N-point discrete Fourier transform of the held analog ...

  8. MOSFET analog memory circuit achieves long duration signal storage

    Science.gov (United States)

    1966-01-01

    Memory circuit maintains the signal voltage at the output of an analog signal amplifier when the input signal is interrupted or removed. The circuit uses MOSFET /Metal Oxide Semiconductor Field Effect Transistor/ devices as voltage-controlled switches, triggered by an external voltage-sensing device.

  9. 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.

  10. Pu oxidation state distributions in suspensions of the Mont Terri Opalinus Clay isolate Sporomusa sp. MT-2.99

    Energy Technology Data Exchange (ETDEWEB)

    Moll, Henry [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Biogeochemistry; Cherkouk, Andrea [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). HZDR Young Investigator Group; Bok, Frank [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes

    2017-06-01

    The time-dependent {sup 242}Pu oxidation state distribution in the presence of Sporomusa sp. cells as a function of pH with or without Na-pyruvate was analyzed. In all cases, the presence of bacterial cells enhanced removal of Pu from solution and accelerated Pu interaction reactions, e.g. biosorption and bioreduction.

  11. Pu oxidation state distributions in suspensions of the Mont Terri Opalinus Clay isolate Sporomusa sp. MT-2.99

    International Nuclear Information System (INIS)

    Moll, Henry; Cherkouk, Andrea; Bok, Frank

    2017-01-01

    The time-dependent "2"4"2Pu oxidation state distribution in the presence of Sporomusa sp. cells as a function of pH with or without Na-pyruvate was analyzed. In all cases, the presence of bacterial cells enhanced removal of Pu from solution and accelerated Pu interaction reactions, e.g. biosorption and bioreduction.

  12. Molecular modeling of fentanyl analogs

    Directory of Open Access Journals (Sweden)

    LJILJANA DOSEN-MICOVIC

    2004-11-01

    Full Text Available Fentanyl is a highly potent and clinically widely used narcotic analgesic. A large number of its analogs have been synthesized, some of which (sufentanil and alfentanyl are also in clinical use. Theoretical studies, in recent years, afforded a better understanding of the structure-activity relationships of this class of opiates and allowed insight into the molecular mechanism of the interactions of fentanyl analogs with their receptors. An overview of the current computational techniques for modeling fentanyl analogs, their receptors and ligand-receptor interactions is presented in this paper.

  13. Gemini analogs of vitamin D.

    Science.gov (United States)

    Pazos, Gonzalo; Rivadulla, Marcos L; Pérez-García, Xenxo; Gandara, Zoila; Pérez, Manuel

    2014-01-01

    The Gemini analogs are the last significant contribution to the family of vitamin D derivatives in medicine, for the treatment of cancer. The first Gemini analog was characterized by two symmetric side chains at C-20. Following numerous modifications, the most active analog bears a C-23-triple bond, C-26, 27- hexafluoro substituents on one side chain and a terminal trideuteromethylhydroxy group on the other side chain. This progression was possible due to improvements in the synthetic methods for the preparation of these derivatives, which allowed for increasing molecular complexity and complete diastereoselective control at C-20 and the substituted sidechains.

  14. Arsenic K-edge X-ray absorption near-edge spectroscopy to determine oxidation states of arsenic of a coastal aquifer–aquitard system

    International Nuclear Information System (INIS)

    Wang, Ya; Jiao, Jiu Jimmy; Zhu, Sanyuan; Li, Yiliang

    2013-01-01

    Determination of oxidation states of solid-phase arsenic in bulk sediments is a valuable step in the evaluation of its bioavailability and environmental fate in deposits, but is difficult when the sediments have low arsenic contents and heterogeneous distribution of arsenic species. As K-edge X-ray absorption near-edge spectroscopy (XANES) was used to determine quantitatively the oxidation states of arsenic in sediments collected from different depths of boreholes in the Pearl River Delta, China, where the highest aquatic arsenic concentration is 161.4 μg/L, but the highest solid arsenic content only 39.6 mg/kg. The results demonstrated that XANES is efficient in determining arsenic oxidation states of the sediments with low arsenic contents and multiple arsenic species. The study on the high-resolution vertical variations of arsenic oxidation states also indicated that these states are influenced strongly by groundwater activities. With the help of geochemical data, solid arsenic speciation, toxicity and availability were further discussed. -- Highlights: •XANES is efficient in determining arsenic oxidation states of the bulk sediments. •Distribution of arsenic oxidation states is consistent with geochemical conditions. •Arsenic oxidation states are influenced strongly by groundwater activities. -- As K-edge X-ray absorption near-edge spectroscopy is efficient in determining arsenic oxidation states of the bulk sediments with low arsenic contents and heterogeneous distribution of arsenic species

  15. 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.

  16. Oxidative Stress State Is Associated with Left Ventricular Mechanics Changes, Measured by Speckle Tracking in Essential Hypertensive Patients

    Directory of Open Access Journals (Sweden)

    Luis Antonio Moreno-Ruíz

    2015-01-01

    Full Text Available The oxidative stress state is characterized by an increase in oxygen reactive species that overwhelms the antioxidant defense; we do not know if these pathological changes are correlated with alterations in left ventricular mechanics. The aim was correlating the oxidative stress state with the left ventricular global longitudinal strain (GLS and the left ventricular end diastolic pressure (LVEDP. Twenty-five patients with essential hypertension and 25 controls paired by age and gender were studied. All of the participants were subjected to echocardiography and biochemical determination of oxidative stress markers. The hypertensive patients, compared with control subjects, had significantly (p<0.05 higher levels of oxidized proteins (5.03±1.05 versus 4.06±0.63 nmol/mg, lower levels of extracellular superoxide dismutase (EC-SOD activity (0.045±0.02 versus 0.082±0.02 U/mg, higher LVEDP (16.2±4.5 versus 11.3±1.6 mm Hg, and lower GLS (−12% versus −16%. Both groups had preserved ejection fraction and the results showed a positive correlation of oxidized proteins with GLS (r=0.386, p=0.006 and LVEDP (r=0.389, p=0.005; we also found a negative correlation of EC-SOD activity with GLS (r=-0.404, p=0.004 and LVEDP (r=-0.347, p=0.014.

  17. System Tb-Fe-O: thermodynamic properties of ternary oxides using solid-state electrochemical cells

    International Nuclear Information System (INIS)

    Rakshit, S.K.; Parida, S.C.; Dash, S.; Singh, Ziley; Prasad, R.; Venugopal, V.

    2003-01-01

    The standard molar Gibbs free energies of formation of TbFeO 3 (s) and Tb 3 Fe 5 O 12 (s) have been determined using solid-state electrochemical cell employing different solid electrolytes. The reversible emfs of the following solid-state electrochemical cells have been measured in the temperature range 1050≤T/K≤1250. Cell (I):(-)Pt/{TbFeO 3 (s)+Tb 2 O 3 (s)+Fe(s)}//YDT/CSZ//{Fe(s)+Fe 0.95 O(s)}/Pt(+))) (Cell (II):(-)Pt/{Fe(s)+Fe 0.95 O(s)}//CSZ//{TbFeO 3 (s)+Tb 3 Fe 5 O 12 (s)+Fe 3 O 4 (s)}/Pt(+) The oxygen chemical potentials corresponding to the three-phase equilibria involving the ternary oxides have been computed from the emf data. The standard molar Gibbs free energies of formation of solid TbFeO 3 and Tb 3 Fe 5 O 12 calculated by the least-squares regression analysis of the data obtained in the present study are given by {Δ f G compfn m (TbFeO 3 ,s)/(kJ·mol -1 )±3.2}=-1357.5+0.2531·(T/K); (1050≤T/K≤1548);))and({Δ f G compfn m (Tb 3 Fe 5 O 12 ,s)/(kJ·mol -1 )±3.5}=-4901.7+ 0.9997·(T/K); (1050≤T/K≤1250).)) The uncertainty estimates for Δ f G compfn m include the standard deviation in the emf and uncertainty in the data taken from the literature. Based on the thermodynamic information, oxygen potential diagram and chemical potential diagrams were computed for the system Tb-Fe-O at T=1250 K

  18. Studi On Oxidation State Of U In Ba2NdUO6

    International Nuclear Information System (INIS)

    Firman Windarto, Hendri

    1996-01-01

    Ba 2 NdUO 6 is not of the important compounds that is formed from a solidification process for high level liquid waste using super high temperature method Ba 2 NdUO 6 has ordered perovskite structure. The objective of this study is to investigate oxidation state of U in Ba 2 NdUO 6 . The properties of Ba 2 NdUO 6 were observed by using Faraday-type torsion magnetometer and X-ray Photoelectron Spectrometer (XPS). The magnetic susceptibility measured in the temperature range of 4K to room temperature showed that the Ba 2 NdUO 6 is paramagnetism that obeys the Curie-Weiss law. The effective moment of Ba 2 NdUO 6 is 3.04 μB. The results of xPs spectrum showed that the peaks of U4f for Ba 2 NdUO 6 appeared exactly between binding energy of UO 2 and UO 3 . It can be concluded that Ba 2 NdUO 6 has binding energy peaks corresponding to pentavalent uranium

  19. Petrology of chromite in ureilites: Deconvolution of primary oxidation states and secondary reduction processes

    Science.gov (United States)

    Goodrich, Cyrena Anne; Harlow, George E.; Van Orman, James A.; Sutton, Stephen R.; Jercinovic, Michael J.; Mikouchi, Takashi

    2014-06-01

    Ureilites are ultramafic achondrites thought to be residues of partial melting on a carbon-rich asteroid. They show a trend of FeO-variation (olivine Fo from ∼74 to 95) that suggests variation in oxidation state. Whether this variation was established during high-temperature igneous processing on the ureilite parent body (UPB), or preserved from nebular precursors, is a subject of debate. The behavior of chromium in ureilites offers a way to assess redox conditions during their formation and address this issue, independent of Fo. We conducted a petrographic and mineral compositional study of occurrences of chromite (Cr-rich spinel) in ureilites, aimed at determining the origin of the chromite in each occurrence and using primary occurrences to constrain models of ureilite petrogenesis. Chromite was studied in LEW 88774 (Fo 74.2), NWA 766 (Fo 76.7), NWA 3109 (Fo 76.3), HaH 064 (Fo 77.5), LAP 03587 (Fo 74.9), CMS 04048 (Fo 76.4), LAP 02382 (Fo 78.6) and EET 96328 (Fo 85.2). Chromite occurs in LEW 88774 (∼5 vol.%), NWA 766 (event involved initial elevation of T (to 1300-1400 °C), followed by rapid decompression and drop in T (to exclusively in low-Fo samples supports the interpretation that the ureilite FeO-variation was established during igneous processing on the UPB.

  20. Waste management state-of-the-art review for mixed-oxide fuel fabrication facilities

    International Nuclear Information System (INIS)

    Woodsum, H.C.; Goodman, J.

    1977-11-01

    This report provides a state-of-the-art review of the waste management for mixed-oxide (MOX) fuel fabrication facilities. The intent of this report is to focus on those processes and regulatory issues which have a direct bearing on existing and anticipated future management of transuranic (TRU) wastes from a commercial MOX fuel fabrication faciity. Recent government agency actions are reviewed with regard to their impact on existing and projected waste management regulations; and it is concluded that acceleration in the development of regulations, standards, and criteria is one of the most important factors in the implementation of improved MOX plant waste management techniques. ERDA development programs pertaining to the management of TRU wastes have been reviewed and many promising methods for volume reduction of both solid and liquid wastes are discussed. For solid wastes, these methods include compaction, shredding and baling, combustion, acid digestion, and decontamination by electropolishing or by electrolytic treatment. For liquid wastes, treatment options include evaporation, drying, calcination, flocculation, ion exchange, filtration, reverse osmosis, combustion (of combustible organics), and bioprocessing. Based on this review, it is recommended that ERDA continue with its combustible solid waste volume reduction program and complete these development activities by 1979. Following this, a critical evaluation of solid waste volume reduction techniques should be made to select the most promising systems for a commercial MOX fuel facility

  1. Oxidation state of uranium in metamict and annealed zircon: near-infrared spectroscopic quantitative analysis

    CERN Document Server

    Zhang Ming; Ewing, R C

    2003-01-01

    Radiation and thermally induced changes in the oxidation state of uranium in metamict zircon have been systematically analysed, for the first time, using polarized near-infrared spectroscopy. The results showed that in damaged zircon U ions in crystalline domains exhibited relatively sharp, anisotropic signals from tetravalent and pentavalent U ions in crystalline domains (U sub c sub r sub y sub s sub t sub a sub l sup 4 sup + and U sub c sub r sub y sub s sub t sub a sub l sup 5 sup +). The linewidths and peak positions of the 4834 cm sup - sup 1 band (U sub c sub r sub y sub s sub t sub a sub l sup 4 sup + , E || c) and the 6668 cm sup - sup 1 band (U sub c sub r sub y sub s sub t sub a sub l sup 5 sup + , E perp. c) are a non-linear function of the self-radiation dose. They reach nearly constant values at doses greater than approx 3.5 x 10 sup 1 sup 8 alpha-events g sup - sup 1. Quantitative analysis of U sub c sub r sub y sub s sub t sub a sub l sup 4 sup + and U sub c sub r sub y sub s sub t sub a sub l...

  2. Atomic scale imaging of competing polar states in a Ruddlesden–Popper layered oxide

    Science.gov (United States)

    Stone, Greg; Ophus, Colin; Birol, Turan; Ciston, Jim; Lee, Che-Hui; Wang, Ke; Fennie, Craig J.; Schlom, Darrell G.; Alem, Nasim; Gopalan, Venkatraman

    2016-01-01

    Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in Ruddlesden–Popper (RP), An+1BnO3n+1, thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ångstrom resolution in Srn+1TinO3n+1 thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure. PMID:27578622

  3. Atomic scale imaging of competing polar states in a Ruddlesden-Popper layered oxide.

    Science.gov (United States)

    Stone, Greg; Ophus, Colin; Birol, Turan; Ciston, Jim; Lee, Che-Hui; Wang, Ke; Fennie, Craig J; Schlom, Darrell G; Alem, Nasim; Gopalan, Venkatraman

    2016-08-31

    Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in Ruddlesden-Popper (RP), An+1BnO3n+1, thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ångstrom resolution in Srn+1TinO3n+1 thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure.

  4. Carbonate-linked poly(ethylene oxide) polymer electrolytes towards high performance solid state lithium batteries

    International Nuclear Information System (INIS)

    He, Weisheng; Cui, Zili; Liu, Xiaochen; Cui, Yanyan; Chai, Jingchao; Zhou, Xinhong; Liu, Zhihong; Cui, Guanglei

    2017-01-01

    The classic poly(ethylene oxide) (PEO) based solid polymer electrolyte suffers from poor ionic conductivity of ambient temperature, low lithium ion transference number and relatively narrow electrochemical window (<4.0 V vs. Li + /Li). Herein, the carbonate-linked PEO solid polymer such as poly(diethylene glycol carbonate) (PDEC) and poly(triethylene glycol carbonate) (PTEC) were explored to find out the feasibility of resolving above issues. It was proven that the optimized ionic conductivity of PTEC based electrolyte reached up to 1.12 × 10 −5 S cm −1 at 25 °C with a decent lithium ion transference number of 0.39 and a wide electrochemical window about 4.5 V vs. Li + /Li. In addition, the PTEC based Li/LiFePO 4 cell could be reversibly charged and discharged at 0.05 C-rates at ambient temperature. Moreover, the higher voltage Li/LiFe 0.2 Mn 0.8 PO 4 cell (cutoff voltage 4.35 V) possessed considerable rate capability and excellent cycling performance even at ambient temperature. Therefore, these carbonate-linked PEO electrolytes were demonstrated to be fascinating candidates for the next generation solid state lithium batteries simultaneously with high energy and high safety.

  5. 3 and 4 oxidation state element solubilities in borosilicate glasses. Implement to actinides in nuclear glasses

    International Nuclear Information System (INIS)

    Cachia, J.N.

    2005-12-01

    In order to ensure optimal radionuclides containment, the knowledge of the actinide loading limits in nuclear waste glasses and also the comprehension of the solubilization mechanisms of these elements are essential. A first part of this manuscript deals with the study of the differences in solubility of the tri and tetravalent elements (actinides and surrogates) particularly in function of the melting temperature. The results obtained indicate that trivalent elements (La, Gd, Nd, Am, Cm) exhibit a higher solubility than tetravalent elements (Hf, Th, Pu). Consequently, it was planned to reduce plutonium at the oxidation state (III), the later being essentially tetravalent in borosilicate glasses. An innovating reduction process of multi-valent elements (cerium, plutonium) using silicon nitride has been developed in a second part of this work. Reduced plutonium-bearing glasses synthesized by Si 3 N 4 addition made it possible to double the plutonium solubility from 2 to 4 wt% at 1200 deg C. A structural approach to investigate the differences between tri and tetravalent elements was finally undertaken. These investigations were carried out by X-rays Absorption Spectroscopy (EXAFS) and NMR. Trivalent rare earth and actinide elements seem to behave as network modifiers while tetravalent elements rather present true intermediaries' behaviour. (author)

  6. Flash and Continuous Photolysis Studies of the Thionitrosyl Complex Cr(CH3CN)5(NS)2+ and the Nitric Oxide Analogs. Reactions of Nitrogen Monosulfide in Solution

    DEFF Research Database (Denmark)

    Dethlefsen, Johannes Wied; Hedegård, Erik; Rimmer, R. Dale

    2009-01-01

    Photolysis of the thionitrosyl complex Cr(CH3CN)5(NS)2+ (1) in acetonitrile solution leads to the dissociation of nitrogen monosulfide (NS).  In deaerated solution, this reaction is reversible, and flash photolysis studies demonstrate that NS reacts with Cr(CH3CN)62+ according to the rate law d[1...... dependent quantum yields of 0.3-1.0 mol/Einstein. Mass spectroscopic studies of the product solutions demonstrate formation of S8, presumably from the decomposition of NS. The quantitative photochemical behaviors of 1 and the nitrosyl analog 2 are compared. Udgivelsesdato: Jan....

  7. Analog elements for transuranic chemistries

    International Nuclear Information System (INIS)

    Weimer, W.C.

    1982-01-01

    The analytical technique for measuring trace concentrations of the analog rare earth elements has been refined for optimal detection. The technique has been used to determine the rare earth concentrations in a series of geological and biological materials, including samples harvested from controlled lysimeter investigations. These studies have demonstrated that any of the trivalent rare earth elements may be used as analog elements for the trivalent transuranics, americium and curium

  8. CMOS Analog IC Design: Fundamentals

    OpenAIRE

    Bruun, Erik

    2018-01-01

    This book is intended for use as the main textbook for an introductory course in CMOS analog integrated circuit design. It is aimed at electronics engineering students who have followed basic courses in mathematics, physics, circuit theory, electronics and signal processing. It takes the students directly from a basic level to a level where they can start working on simple analog IC design projects or continue their studies using more advanced textbooks in the field. A distinct feature of thi...

  9. Exploratory Characterization of Phenolic Compounds with Demonstrated Anti-Diabetic Activity in Guava Leaves at Different Oxidation States

    Directory of Open Access Journals (Sweden)

    Elixabet Díaz-de-Cerio

    2016-05-01

    Full Text Available Psidium guajava L. is widely used like food and in folk medicine all around the world. Many studies have demonstrated that guava leaves have anti-hyperglycemic and anti-hyperlipidemic activities, among others, and that these activities belong mainly to phenolic compounds, although it is known that phenolic composition in guava tree varies throughout seasonal changes. Andalusia is one of the regions in Europe where guava is grown, thus, the aim of this work was to study the phenolic compounds present in Andalusian guava leaves at different oxidation states (low, medium, and high. The phenolic compounds in guava leaves were determined by HPLC-DAD-ESI-QTOF-MS. The results obtained by chromatographic analysis reported that guava leaves with low degree of oxidation had a higher content of flavonols, gallic, and ellagic derivatives compared to the other two guava leaf samples. Contrary, high oxidation state guava leaves reported the highest content of cyanidin-glucoside that was 2.6 and 15 times higher than guava leaves with medium and low oxidation state, respectively. The QTOF platform permitted the determination of several phenolic compounds with anti-diabetic properties and provided new information about guava leaf phenolic composition that could be useful for nutraceutical production.

  10. Exploratory Characterization of Phenolic Compounds with Demonstrated Anti-Diabetic Activity in Guava Leaves at Different Oxidation States.

    Science.gov (United States)

    Díaz-de-Cerio, Elixabet; Verardo, Vito; Gómez-Caravaca, Ana María; Fernández-Gutiérrez, Alberto; Segura-Carretero, Antonio

    2016-05-11

    Psidium guajava L. is widely used like food and in folk medicine all around the world. Many studies have demonstrated that guava leaves have anti-hyperglycemic and anti-hyperlipidemic activities, among others, and that these activities belong mainly to phenolic compounds, although it is known that phenolic composition in guava tree varies throughout seasonal changes. Andalusia is one of the regions in Europe where guava is grown, thus, the aim of this work was to study the phenolic compounds present in Andalusian guava leaves at different oxidation states (low, medium, and high). The phenolic compounds in guava leaves were determined by HPLC-DAD-ESI-QTOF-MS. The results obtained by chromatographic analysis reported that guava leaves with low degree of oxidation had a higher content of flavonols, gallic, and ellagic derivatives compared to the other two guava leaf samples. Contrary, high oxidation state guava leaves reported the highest content of cyanidin-glucoside that was 2.6 and 15 times higher than guava leaves with medium and low oxidation state, respectively. The QTOF platform permitted the determination of several phenolic compounds with anti-diabetic properties and provided new information about guava leaf phenolic composition that could be useful for nutraceutical production.

  11. Exploratory Characterization of Phenolic Compounds with Demonstrated Anti-Diabetic Activity in Guava Leaves at Different Oxidation States

    Science.gov (United States)

    Díaz-de-Cerio, Elixabet; Verardo, Vito; Gómez-Caravaca, Ana María; Fernández-Gutiérrez, Alberto; Segura-Carretero, Antonio

    2016-01-01

    Psidium guajava L. is widely used like food and in folk medicine all around the world. Many studies have demonstrated that guava leaves have anti-hyperglycemic and anti-hyperlipidemic activities, among others, and that these activities belong mainly to phenolic compounds, although it is known that phenolic composition in guava tree varies throughout seasonal changes. Andalusia is one of the regions in Europe where guava is grown, thus, the aim of this work was to study the phenolic compounds present in Andalusian guava leaves at different oxidation states (low, medium, and high). The phenolic compounds in guava leaves were determined by HPLC-DAD-ESI-QTOF-MS. The results obtained by chromatographic analysis reported that guava leaves with low degree of oxidation had a higher content of flavonols, gallic, and ellagic derivatives compared to the other two guava leaf samples. Contrary, high oxidation state guava leaves reported the highest content of cyanidin-glucoside that was 2.6 and 15 times higher than guava leaves with medium and low oxidation state, respectively. The QTOF platform permitted the determination of several phenolic compounds with anti-diabetic properties and provided new information about guava leaf phenolic composition that could be useful for nutraceutical production. PMID:27187352

  12. The protonation state around TyrD/TyrD• in photosystem II is reflected in its biphasic oxidation kinetics.

    Science.gov (United States)

    Sjöholm, Johannes; Ho, Felix; Ahmadova, Nigar; Brinkert, Katharina; Hammarström, Leif; Mamedov, Fikret; Styring, Stenbjörn

    2017-02-01

    The tyrosine residue D2-Tyr160 (Tyr D ) in photosystem II (PSII) can be oxidized through charge equilibrium with the oxygen evolving complex in PSII. The kinetics of the electron transfer from Tyr D has been followed using time-resolved EPR spectroscopy after triggering the oxidation of pre-reduced Tyr D by a short laser flash. After its oxidation Tyr D is observed as a neutral radical (Tyr D • ) indicating that the oxidation is coupled to a deprotonation event. The redox state of Tyr D was reported to be determined by the two water positions identified in the crystal structure of PSII [Saito et al. (2013) Proc. Natl. Acad. Sci. USA 110, 7690]. To assess the mechanism of the proton coupled electron transfer of Tyr D the oxidation kinetics has been followed in the presence of deuterated buffers, thereby resolving the kinetic isotope effect (KIE) of Tyr D oxidation at different H/D concentrations. Two kinetic phases of Tyr D oxidation - the fast phase (msec-sec time range) and the slow phase (tens of seconds time range) were resolved as was previously reported [Vass and Styring (1991) Biochemistry 30, 830]. In the presence of deuterated buffers the kinetics was significantly slower compared to normal buffers. Furthermore, although the kinetics were faster at both high pH and pD values the observed KIE was found to be similar (~2.4) over the whole pL range investigated. We assign the fast and slow oxidation phases to two populations of PSII centers with different water positions, proximal and distal respectively, and discuss possible deprotonation events in the vicinity of Tyr D . Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Rapid Synthesis of Lead Oxide Nanorods by One-step Solid-state Chemical Reaction at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    CAO, Ya-Li(曹亚丽); JIA, Dian-Zeng(贾殿赠); LIU, Lang(刘浪); LUO, Jian-Min(骆建敏)

    2004-01-01

    A simple and facile method was reported to synthesize lead oxide nanorods. Nanorods of lead oxide were obtained directly from grinding solid metal salt and sodium hydroxide in agate mortar with the assistance of a suitable nonionic surfactant in only one step, which is different from the result of hydroxide in solution. The product has been characterized by XRD, TEM and SEM. The formation mechanism of rod-like morphology is discussed and the surfactant plays an important soft-template role in modifying the interface of solid-state reaction and according process of rod-formation.

  14. 22nd Workshop on Advances in Analog Circuit Design

    CERN Document Server

    Makinwa, Kofi; Harpe, Pieter

    2014-01-01

    This book is based on the 18 tutorials presented during the 22nd workshop on Advances in Analog Circuit Design.  Expert designers present readers with information about a variety of topics at the frontier of analog circuit design, including frequency reference, power management for systems-on-chip, and smart wireless interfaces.  This book serves as a valuable reference to the state-of-the-art, for anyone involved in analog circuit research and development.    ·         Provides a state-of-the-art reference in analog circuit design, written by experts from industry and academia; ·         Presents material in a tutorial-based format; ·         Includes coverage of frequency reference, power management for systems-on-chip, and smart wireless interfaces.

  15. Investigation of electrochemical behaviour and structure of oxide films on Ni60Nb40 alloy in amorphous and crystalline states

    International Nuclear Information System (INIS)

    Tomashov, N.D.; Skvortsova, I.B.; Gorodetskij, A.E.; Bogomolov, D.B.

    1987-01-01

    Electrochemical properties of Ni 60 Nb 40 alloy in amorphous and crystalline states as well as structure of oxide films forming during anode polarization in electrolytes on the surface of this alloy in both its states are investigated. It is stated that increased passive ability of Ni 60 Nb 40 alloys in amorphous state and high efficiency of chlorine evolution (2 n NaCl+HCl up to pH=0) anode process in comparison with crystalline state are defined by increased homogeneity and uniformity of passive films forming on amorphous alloy and their increased electron conductivity, that is in direct dependence on different structure of passive films forming on alloys in amorphous and crystalline states

  16. Analogous Three-Dimensional Constructive Interference in Steady State Sequences Enhance the Utility of Three-Dimensional Time of Flight Magnetic Resonance Angiography in Delineating Lenticulostriate Arteries in Insular Gliomas: Evidence from a Prospective Clinicoradiologic Analysis of 48 Patients.

    Science.gov (United States)

    Rao, Arun S; Thakar, Sumit; Sai Kiran, Narayanam Anantha; Aryan, Saritha; Mohan, Dilip; Hegde, Alangar S

    2018-01-01

    Three-dimensional (3D) time of flight (TOF) imaging is the current gold standard for noninvasive, preoperative localization of lenticulostriate arteries (LSAs) in insular gliomas; however, the utility of this modality depends on tumor intensity. Over a 3-year period, 48 consecutive patients with insular gliomas were prospectively evaluated. Location of LSAs and their relationship with the tumor were determined using a combination of contrast-enhanced coronal 3D TOF magnetic resonance angiography and coronal 3D constructive interference in steady state (CISS) sequences. These findings were analyzed with respect to extent of tumor resection and early postoperative motor outcome. Tumor was clearly visualized in 29 (60.4%) patients with T1-hypointense tumors using 3D TOF and in all patients using CISS sequences. Using combined 3D TOF and CISS, LSA-tumor interface was well seen in 47 patients, including all patients with T1-heterointense or T1-isointense tumors. Extent of resection was higher in the LSA-pushed group compared with the LSA-encased group. In the LSA-encased group, 6 (12.5%) patients developed postoperative hemiparesis; 2 (4.2%) cases were attributed to LSA injury. Contrast-enhanced 3D TOF can delineate LSAs in almost all insular gliomas but is limited in identifying the LSA-tumor interface. This limitation can be overcome by addition of analogous CISS sequences that delineate the LSA-tumor interface regardless of tumor intensity. Combined 3D TOF and 3D CISS is a useful tool for surgical planning and safer resections of insular tumors and may have added surgical relevance when included as an intraoperative adjunct. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Assigning Oxidation States to Organic Compounds via Predictions from X-Ray Photoelectron Spectroscopy: A Discussion of Approaches and Recommended Improvements

    Science.gov (United States)

    Gupta, Vipul; Ganegoda, Hasitha; Engelhard, Mark H.; Terry, Jeff; Linford, Matthew R.

    2014-01-01

    The traditional assignment of oxidation states to organic molecules is problematic. Accordingly, in 1999, Calzaferri proposed a simple and elegant solution that is based on the similar electronegativities of carbon and hydrogen: hydrogen would be assigned an oxidation state of zero when bonded to carbon. Here, we show that X-ray photoelectron…

  18. Sulfur diffusion in dacitic melt at various oxidation states: Implications for volcanic degassing

    Science.gov (United States)

    Lierenfeld, Matthias Bernhard; Zajacz, Zoltán; Bachmann, Olivier; Ulmer, Peter

    2018-04-01

    The diffusivity of S in a hydrous dacitic melt (4.5-6.0 wt.% H2O) has been investigated in the temperature (T) and pressure (P) range of 950 °C to 1100 °C and 200 to 250 MPa, respectively. Three series of experiments were conducted at relatively low oxygen fugacity (fO2) conditions [0.8 log units below fayalite-magnetite-quartz equilibrium (FMQ -0.8); referred to as "low fO2"] and high fO2 conditions (FMQ +2.5; referred to as "high fO2") to determine if the diffusivity of S is affected by its oxidation state and speciation. Sulfur concentration profiles were measured by electron microprobe and the diffusion coefficient (D) was calculated by fitting these profiles. Sulfur diffusion is approximately one order of magnitude faster when S is dominantly present as sulfide species (low fO2) in comparison to the sulfate dominated experiments (high fO2). The following Arrhenian equations were obtained for high and low fO2 conditions at 200 MPa: high fO2: D = 10-5.92±0.86 * exp ({-137.3±21.5 kJ/mol}/{RT}) low fO2: D = 10-5.18±1.39 * exp ({-125.7±34.4 kJ/mol}/{RT}) where D is the average diffusion coefficient in m2 s-1, R is the gas constant in 8.3144 J mol-1 K-1 and T is the temperature in K. Our results demonstrate for the first time in natural melts that S diffusion is strongly sensitive to fO2. Our S diffusivities under low fO2 conditions are only slightly slower of those found for H2O, suggesting that S can be rather efficiently purged from reduced dacitic melts during volcanic eruptions. However, for more oxidized systems (e.g. subduction zones), S diffusion will be much slower and will hinder equilibrium syn-eruptive degassing during rapid decompression. Therefore, we conclude that the "excess" measured during many explosive volcanic eruptions in arcs is dominantly derived from S-rich bubble accumulation in the eruptible portion of the magma reservoir.

  19. Utah Marbles and Mars Blueberries: Comparitive Terrestrial Analogs for Hematite Concretions on Mars

    Science.gov (United States)

    Chan, M. A.; Beitler, B.; Parry, W. T.; Ormö, J.; Komatsu, G.

    2005-03-01

    Compelling comparisons show why Utah iron oxide-cemented "marbles" are a good analog for Mars hematite "blueberries". Terrestrial examples offer valuable models for interpreting the diagenetic history and importance of water on Mars.

  20. Producing and Recognizing Analogical Relations

    Science.gov (United States)

    Lipkens, Regina; Hayes, Steven C

    2009-01-01

    Analogical reasoning is an important component of intelligent behavior, and a key test of any approach to human language and cognition. Only a limited amount of empirical work has been conducted from a behavior analytic point of view, most of that within Relational Frame Theory (RFT), which views analogy as a matter of deriving relations among relations. The present series of four studies expands previous work by exploring the applicability of this model of analogy to topography-based rather than merely selection-based responses and by extending the work into additional relations, including nonsymmetrical ones. In each of the four studies participants pretrained in contextual control over nonarbitrary stimulus relations of sameness and opposition, or of sameness, smaller than, and larger than, learned arbitrary stimulus relations in the presence of these relational cues and derived analogies involving directly trained relations and derived relations of mutual and combinatorial entailment, measured using a variety of productive and selection-based measures. In Experiment 1 participants successfully recognized analogies among stimulus networks containing same and opposite relations; in Experiment 2 analogy was successfully used to extend derived relations to pairs of novel stimuli; in Experiment 3 the procedure used in Experiment 1 was extended to nonsymmetrical comparative relations; in Experiment 4 the procedure used in Experiment 2 was extended to nonsymmetrical comparative relations. Although not every participant showed the effects predicted, overall the procedures occasioned relational responses consistent with an RFT account that have not yet been demonstrated in a behavior-analytic laboratory setting, including productive responding on the basis of analogies. PMID:19230515

  1. Triplet-State Dissolved Organic Matter Quantum Yields and Lifetimes from Direct Observation of Aromatic Amine Oxidation.

    Science.gov (United States)

    Schmitt, Markus; Erickson, Paul R; McNeill, Kristopher

    2017-11-21

    Excited triplet state chromophoric dissolved organic matter ( 3 CDOM*) is a short-lived mixture of excited-state species that plays important roles in aquatic photochemical processes. Unlike the study of the triplet states of well-defined molecules, which are amenable to transient absorbance spectroscopy, the study of 3 CDOM* is hampered by it being a complex mixture and its low average intersystem crossing quantum yield (Φ ISC ). This study is an alternative approach to investigating 3 CDOM* using transient absorption laser spectroscopy. The radical cation of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), formed through oxidation by 3 CDOM*, was directly observable by transient absorption spectroscopy and was used to probe basic photophysical properties of 3 CDOM*. Quenching and control experiments verified that TMPD •+ was formed from 3 CDOM* under anoxic conditions. Model triplet sensitizers with a wide range of excited triplet state reduction potentials and CDOM oxidized TMPD at near diffusion-controlled rates. This gives support to the idea that a large cross-section of 3 CDOM* moieties are able to oxidize TMPD and that the complex mixture of 3 CDOM* can be simplified to a single signal. Using the TMPD •+ transient, the natural triplet lifetime and Φ ISC for different DOM isolates and natural waters were quantified; values ranged from 12 to 26 μs and 4.1-7.8%, respectively.

  2. The Oxidation State of Fe in Glasses from the Galapagos Archipelago: Variable Oxygen Fugacity as a Function of Mantle Source

    Science.gov (United States)

    Peterson, M. E.; Kelley, K. A.; Cottrell, E.; Saal, A. E.; Kurz, M. D.

    2015-12-01

    The oxidation state of the mantle plays an intrinsic role in the magmatic evolution of the Earth. Here we present new μ-XANES measurements of Fe3+/ΣFe ratios (a proxy for ƒO2) in a suite of submarine glasses from the Galapagos Archipelago. Using previously presented major, trace, and volatile elements and isotopic data for 4 groups of glass that come from distinct mantle sources (depleted upper mantle, 2 recycled, and a primitive mantle source) we show that Fe3+/ΣFe ratios vary both with the influence of shallow level processes and with variations in mantle source. Fe3+/ΣFe ratios increase with differentiation (i.e. decreasing MgO), but show a large variation at a given MgO. Progressive degassing of sulfur accompanies decreasing Fe3+/ΣFe ratios, while assimilation of hydrothermally altered crust (as indicated by increasing Sr/Sr*) is shown to increase Fe3+/ΣFe ratios. After taking these processes into account, there is still variability in the Fe3+/ΣFe ratios of the isotopically distinct sample suites studied, yielding a magmatic ƒO2 that ranges from ΔQFM = +0.16 to +0.74 (error ITE = enriched Sr and Pb isotopes) shows evidence of mixing between oxidized and reduced sources (ITE oxidized end-member = 0.177). This suggests that mantle sources in the Galapagos that are thought to contain recycled components (i.e., WD and ITE groups) have distinct oxidation states. The high 3He/4He Fernandina samples (HHe group) are shown to be the most oxidized (ave. 0.175 ± 0.006). With C/3He ratios an order of magnitude greater than MORB this suggests that the primitive mantle is a more carbonated and oxidized source than the depleted upper mantle.

  3. Oxidation-state distribution of plutonium in surface and subsurface waters at Thule, northwest Greenland

    International Nuclear Information System (INIS)

    McMahon, C.A.; Leon Vintro, L.; Mitchell, P.I.; Dahlgaard, H.

    2000-01-01

    The speciation of plutonium in Arctic waters sampled on the northwest Greenland shelf in August 1997 is discussed in this paper. Specifically, we report the results of analyses carried out on seawater sampled (a) close to the Thule air base where, in 1968, a US military aircraft carrying four nuclear weapons crashed on sea ice, releasing kilogram quantities of plutonium to the snow pack and underlying seabed sediments, and (b) at a reference station (Upernavik) located ∼400 km to the south. The data show that most of the plutonium in the dissolved phase at Thule is in the form of Pu(V, VI) (mean: 68±6%; n=6), with little if any distinction apparent between surface and bottom waters. Further, the oxidation state distribution at stations close to the accident site is similar to that measured at Upernavik, remote from this site. It is also similar to the distribution observed in shelf waters at mid-latitudes, suggesting that the underlying processes controlling plutonium speciation are insensitive to temperature over the range 0-25 deg. C. Measurements using tangential-flow ultrafiltration indicate that virtually all of the plutonium (including the fraction in a reduced chemical form) is present as fully dissolved species. Most of this plutonium would seem to be of weapons fallout origin, as the mean 238 Pu/ 239,240 Pu activity ratio in the water column (dissolved phase) at Thule (0.06±0.02; n=10) is similar to the global fallout ratio at this latitude (∼0.04). Thus, there is little evidence of weapons-grade plutonium in the water column at Thule at the present time

  4. The changing face of lower tropospheric sulfur oxides in the United States

    Directory of Open Access Journals (Sweden)

    G. M. Hidy

    2016-12-01

    Full Text Available Abstract Sulfur oxides, sulfur dioxide and airborne sulfate, SOx, are short-lived species in the troposphere whose concentrations in air and precipitation have changed dramatically in association with fossil fuel combustion. The historic rise in concentration is coincident with the era of the so-called “Anthropocene.” Unlike concentrations of long-lived species such as carbon dioxide, atmospheric SOx in the United States (US peaked between 1970 and 2005 then declined. The rise and fall of SOx is traced by comparing national data on emission changes, ambient concentrations, and precipitation sulfate from prior to World War II to the present. Surface SOx concentrations and precipitation sulfate have decreased with emissions in most parts of the US after the late 1970s. Continued reduction toward a natural “background” condition has depended on aggressive management of anthropogenic emission sources. Annual average ambient concentrations of SO2 and SO4 have become more uniform across the US at levels of 1–3 ppbv and 0.3–3 µg/m3, respectively. Precipitation SO4 has a nominal concentration generally less than 0.5 mg/L. The effective lifetime of SOx in the troposphere is a few days. This duration limits the spatial extent of emission source influence of SOx to regional scales, wherein spatial gradients in species concentrations lead to variations in human exposure and impacts on vulnerable terrestrial and aquatic ecosystems. The effects of domestic emission reductions on SOx levels are moderated by intra- and intercontinental transport of SOx from Canada, Mexico, Asia and elsewhere. The trends in tropospheric SOx concentrations illustrate the results of more than a century of rising public awareness and action to progressively reduce a US environmental risk, accomplished with advances in energy production technology that have maintained economic well-being.

  5. Global analysis of genetic variation in human arsenic (+ 3 oxidation state) methyltransferase (AS3MT)

    International Nuclear Information System (INIS)

    Fujihara, Junko; Soejima, Mikiko; Yasuda, Toshihiro; Koda, Yoshiro; Agusa, Tetsuro; Kunito, Takashi; Tongu, Miki; Yamada, Takaya; Takeshita, Haruo

    2010-01-01

    Human arsenic (+ 3 oxidation state) methyltransferase (AS3MT) is known to catalyze the methylation of arsenite. The objective of this study was to investigate the diversity of the AS3MT gene at the global level. The distribution of 18 single nucleotide polymorphisms (SNPs) in AS3MT was performed in 827 individuals from 10 populations (Japanese, Korean, Chinese, Mongolian, Tibetans, Sri Lankan Tamils, Sri Lankan Sinhalese, Nepal Tamangs, Ovambo, and Ghanaian). In the African populations, the A allele in A6144T was not observed; the allele frequencies of C35587 were much lower than those in other populations; the allele frequencies of A37616 and C37950 were relatively higher than those in other populations. Among Asian populations, Mongolians showed a different genotype distribution pattern. A lower C3963 and T6144 frequencies were observed, and, in the C37616A and T37950C polymorphism, the Mongolian population showed higher A37616 and C37950 allele frequencies than other Asian populations, similarly to the African populations. A total of 66 haplotypes were observed in the Ovambo, 48, in the Ghanaian, 99, in the Japanese, 103, in the Korean, 103, in the South Chinese, 20, in the Sri Lankan Tamil, 12, in the Sri Lankan Sinhalese, 21, in the Nepal Tamang, 50, in the Tibetan, and 45, in the Mongolian populations. The D' values between the SNP pairs were extremely high in the Sri Lankan Sinhalese population. Relatively higher D' values were observed in Mongolian and Sri Lankan Tamil populations. Network analysis showed two clusters that may have different origins, African and Asians (Chinese and/or Japanese). The present study is the first to demonstrate the existence of genetic heterogeneity in a world wide distribution of 18 SNPs in AS3MT.

  6. Metabolomic profiles of arsenic (+3 oxidation state) methyltransferase knockout mice: Effect of sex and arsenic exposure

    Science.gov (United States)

    Huang, Madelyn C.; Douillet, Christelle; Su, Mingming; Zhou, Kejun; Wu, Tao; Chen, Wenlian; Galanko, Joseph A.; Drobná, Zuzana; Saunders, R. Jesse; Martin, Elizabeth; Fry, Rebecca C.; Jia, Wei; Stýblo, Miroslav

    2016-01-01

    Arsenic (+3 oxidation state) methyltransferase (As3mt) is the key enzyme in the pathway for methylation of inorganic arsenic (iAs). Altered As3mt expression and AS3MT polymorphism have been linked to changes in iAs metabolism and in susceptibility to iAs toxicity in laboratory models and in humans. As3mt-knockout mice have been used to study the association between iAs metabolism and adverse effects of iAs exposure. However, little is known about systemic changes in metabolism of these mice and how these changes lead to their increased susceptibility to iAs toxicity. Here, we compared plasma and urinary metabolomes of male and female wild-type (WT) and As3mt-KO (KO) C57BL6 mice and examined metabolomic shifts associated with iAs exposure in drinking water. Surprisingly, exposure to 1 ppm As elicited only small changes in the metabolite profiles of either WT or KO mice. In contrast, comparisons of KO mice with WT mice revealed significant differences in plasma and urinary metabolites associated with lipid (phosphatidylcholines, cytidine, acyl-carnitine), amino acid (hippuric acid, acetylglycine, urea), and carbohydrate (L-sorbose, galactonic acid, gluconic acid) metabolism. Notably, most of these differences were sex-specific. Sex-specific differences were also found between WT and KO mice in plasma triglyceride and lipoprotein cholesterol levels. Some of the differentially changed metabolites (phosphatidylcholines, carnosine, and sarcosine) are substrates or products of reactions catalyzed by other methyltransferases. These results suggest that As3mt KO alters major metabolic pathways in a sex-specific manner, independent of iAs treatment, and that As3mt may be involved in other cellular processes beyond iAs methylation. PMID:26883664

  7. Determination of Pu Oxidation states in the HCl Media Using with UV-Visible Absorption Spectroscopic Techniques

    International Nuclear Information System (INIS)

    Lee, Myung Ho; Suh, Mu Yeol; Park, Kyoung Kyun; Park, Yeong Jae; Kim, Won Ho

    2006-01-01

    The spectroscopic characteristics of Pu (III, IV, V, VI) in the HCl media were investigated by measuring Pu oxidation states using a UV-Vis-NIR spectrophotometer (400-1200 nm) after adjusting Pu oxidation states with oxidation/reduction reagents. Pu in stock solution was reduced to Pu(III) with NH 2 OH · HCl, and oxidized to Pu(IV) and Pu(VI) with NaNO 2 and HCIO 4 , respectively. Also, Pu(V) was adjusted in the Pu(VI) solution with NH 2 OH · HCl. The major absorption peaks of Pu (IV) and Pu(III) were measured in the 470 nm and 600 nm, respectively. The major absorption peaks of Pu (VI) and Pu(V) were measured in the 830 nm and 1135 nm, respectively. There was not found to be significant changes of UV-V is absorption spectra for Pu(III), Pu(IV) and Pu(VI) with aging time, except that an unstable Pu(V) immediately reduced to Pu(III).

  8. V6O13 films by control of the oxidation state from aqueous precursor to crystalline phase.

    Science.gov (United States)

    Peys, Nick; Ling, Yun; Dewulf, Daan; Gielis, Sven; De Dobbelaere, Christopher; Cuypers, Daniel; Adriaensens, Peter; Van Doorslaer, Sabine; De Gendt, Stefan; Hardy, An; Van Bael, Marlies K

    2013-01-28

    An aqueous deposition process for V(6)O(13) films is developed whereby the vanadium oxidation state is continuously controlled throughout the entire process. In the precursor stage, a controlled wet chemical reduction of the vanadium(V) source with oxalic acid is achieved and monitored by (51)Vanadium Nuclear Magnetic Resonance ((51)V-NMR) and Ultraviolet-Visible (UV-Vis) spectroscopy. The resulting vanadium(IV) species in the aqueous solution are identified as mononuclear citrato-oxovanadate(IV) complexes by Electron Paramagnetic Resonance (EPR) and Fourier Transform Infra-Red (FTIR) spectroscopy. This precursor is successfully employed for the deposition of uniform, thin films. The optimal deposition and annealing conditions for the formation of crystalline V(6)O(13), including the control of the vanadium oxidation state, are determined through an elaborate study of processing temperature and O(2) partial pressure. To ensure a sub 100 nm adjustable film thickness, a non-oxidative intermediate thermal treatment is carried out at the end of each deposition cycle, allowing maximal precursor decomposition while still avoiding V(IV) oxidation. The resulting surface hydrophilicity, indispensable for the homogeneous deposition of the next layer, is explained by an increased surface roughness and the increased availability of surface vanadyl groups. Crystalline V(6)O(13) with a preferential (002) orientation is obtained after a post deposition annealing in a 0.1% O(2) ambient for thin films with a thickness of 20 nm.

  9. Fast multichannel analog storage system

    International Nuclear Information System (INIS)

    Freytag, D.R.

    1982-11-01

    A Multichannel Analog Storage System based on a commercial 32-channel parallel in/serial out (PISO) analog shift register is described. The basic unit is a single width CAMAC module containing 512 analog cells and the associated logic for data storage and subsequent readout. At sampling rates of up to 30 MHz the signals are strobed directly into the PISO. At higher rates signals are strobed into a fast presampling stage and subsequently transferred in block form into an array of PISO's. Sampling rates of 300 MHz have been achieved with the present device and 1000 MHz are possible with improved signal drivers. The system is well suited for simultaneous handling of many signal channels with moderate numbers of samples in each channel. RMS noise over full scale signal has been measured as 1:3000 (approx. = 11 bit). However, nonlinearities in the response and differences in sensitivity of the analog cells require an elaborate calibration system in order to realize 11 bit accuracy for the analog information

  10. A Semi-Analytical Extraction Method for Interface and Bulk Density of States in Metal Oxide Thin-Film Transistors.

    Science.gov (United States)

    Chen, Weifeng; Wu, Weijing; Zhou, Lei; Xu, Miao; Wang, Lei; Ning, Honglong; Peng, Junbiao

    2018-03-11

    A semi-analytical extraction method of interface and bulk density of states (DOS) is proposed by using the low-frequency capacitance-voltage characteristics and current-voltage characteristics of indium zinc oxide thin-film transistors (IZO TFTs). In this work, an exponential potential distribution along the depth direction of the active layer is assumed and confirmed by numerical solution of Poisson's equation followed by device simulation. The interface DOS is obtained as a superposition of constant deep states and exponential tail states. Moreover, it is shown that the bulk DOS may be represented by the superposition of exponential deep states and exponential tail states. The extracted values of bulk DOS and interface DOS are further verified by comparing the measured transfer and output characteristics of IZO TFTs with the simulation results by a 2D device simulator ATLAS (Silvaco). As a result, the proposed extraction method may be useful for diagnosing and characterising metal oxide TFTs since it is fast to extract interface and bulk density of states (DOS) simultaneously.

  11. A Semi-Analytical Extraction Method for Interface and Bulk Density of States in Metal Oxide Thin-Film Transistors

    Directory of Open Access Journals (Sweden)

    Weifeng Chen

    2018-03-01

    Full Text Available A semi-analytical extraction method of interface and bulk density of states (DOS is proposed by using the low-frequency capacitance–voltage characteristics and current–voltage characteristics of indium zinc oxide thin-film transistors (IZO TFTs. In this work, an exponential potential distribution along the depth direction of the active layer is assumed and confirmed by numerical solution of Poisson’s equation followed by device simulation. The interface DOS is obtained as a superposition of constant deep states and exponential tail states. Moreover, it is shown that the bulk DOS may be represented by the superposition of exponential deep states and exponential tail states. The extracted values of bulk DOS and interface DOS are further verified by comparing the measured transfer and output characteristics of IZO TFTs with the simulation results by a 2D device simulator ATLAS (Silvaco. As a result, the proposed extraction method may be useful for diagnosing and characterising metal oxide TFTs since it is fast to extract interface and bulk density of states (DOS simultaneously.

  12. Non steady-state model for dry oxidation of nuclear wastes metallic containers in long term interim storage conditions

    International Nuclear Information System (INIS)

    Bertrand, Nathalie; Desgranges, Clara; Poquillon, Dominique; Monceau, Daniel

    2006-01-01

    oxidation tests. In a second step, in order to increase the reliability of the long term extrapolations from basic models, a non-steady state numerical model able to take into account several elementary steps is built. The aim is to get a more reliable tool to describe mechanisms that control oxide scale growth in this specific low temperature range. The paper has the following contains: Experimental results; Growth kinetics; Scale morphology; A basic model for kinetics of oxidation; Conclusion of the experimental study; EKINOX: Estimation KINetics OXidation: an advanced model; General description; Equations in the model; Results; Future developments; Conclusion. To summarize, the basic model consists in some extrapolations of available experimental data in the temperature range of interest following simple analytical laws deduced from classical oxidation theories. This leads to a very small oxide scale and thus to the loss of very small amounts of metal even for extrapolations to over 100 years. However, the reliability of this kind of basic models is very poor since it is based on the assumption that a single elementary process controls the oxidation rate. Indeed in the temperature range concerned by long term interim deposit of waste containers, several mechanisms can control the oxidation rate. A numerical model able to take in consideration several growth mechanisms is now in progress. At this stage of development, the originality of the proposed advanced model consists in explicitly calculating the vacancy profiles and treating these as non-conservative species. It is based on an original numerical treatment to correctly and easily describe elimination of vacancies at the metal/oxide interface and thus relative motion between the substrate lattice and the oxide one, even for non-stationary states. It can treat Wagner's model but without the quasi-steady state 'hypothesis or also take into account a partial control of the oxidation process by interfacial reaction. In

  13. Natural analogs for Yucca Mountain

    International Nuclear Information System (INIS)

    Murphy, W.M.

    1995-01-01

    High-level radioactive waste in the US, spent fuels from commercial reactors and nuclear materials generated by defense activities, will remain potentially hazardous for thousands of years. Demonstrable long-term stability of certain geologic and geochemical systems motivates and sustains the concept that high-level waste can be safely isolated in geologic repositories for requisite periods of time. Each geologic repository is unique in its properties and performance with reguard to isolation of nuclear wastes. Studies of processes analogous to waste-form alteration and radioelement transport in environments analogous to Yucca Mountain are being conducted at two sites, described in this article to illustrate uses of natural analog data: the Nopal I uranium deposit in the Sierra Pena Blanca, Mexico, and the Akrotiri archaeological site on the island of Santorini, Greece

  14. Synthetic Analogs of Phospholipid Metabolites as Antimalarials.

    Science.gov (United States)

    1979-07-01

    phosphatidic acid analogs containing ether and phosphonate groups; completely non- hydrolyzable lecithin analogs containing phosphinate and ether groups...substance is a completely non- hydrolyzable analog of lecithin containing ether and phosphonate moieties instead of the normally labile carboxylic and...and also ant-i-phospholipase C (clostridial enzyme) activity. This substance Is a completely non- hydrolyzable analog of lecithin containing ether

  15. Solid-phase extraction of plutonium in various oxidation states from simulated groundwater using N-benzoylphenylhydroxylamine

    International Nuclear Information System (INIS)

    Perevalov, S.A.; Malofeeva, G.I.; Kuzovkina, E.V.; Spivakov, B.Ya.

    2013-01-01

    Solid-phase extraction of plutonium in different individual and mixed oxidation states from simulated groundwater (pH 8.5) was studied. The extraction of plutonium species was carried out in a dynamic mode using DIAPAK C16 cartridges modified by N-benzoylphenylhydroxylamine (BPHA). It was shown that the extent of recovery depends on the oxidation state of plutonium. The extraction of Pu(IV) was at the level of 98-99% regardless of the volume and flow-rate of the sample solution. Pu(V) was extracted by 90-95% and 75-80% from 10- and 100-mL aliquots of the samples, respectively, whereas the extraction of Pu(VI) did not exceed 45-50%. An equimolar mixture of Pu(IV), Pu(V), and Pu(VI) was extracted by 74%. The distribution coefficients (K d ) and kinetic exchange capacities (S) of plutonium in various oxidation states were measured. It was found that during the sorption process, Pu(V) was reduced to Pu(IV) by 80-90% after an hour-long contact with the solid phase. Pu(VI) is reduced to Pu(V) by 34% and to Pu(IV) by 55%. In the case of mixed-valent solution of plutonium, only Pu(V) and Pu(IV) were found in the effluents. (author)

  16. Homoleptic Ce(III) and Ce(IV) Nitroxide Complexes: Significant Stabilization of the 4+ Oxidation State

    Energy Technology Data Exchange (ETDEWEB)

    Bogart, Justin A.; Lewis, Andrew J.; Medling, Scott A.; Piro, Nicholas A.; Carroll, Patrick J.; Booth, Corwin H.; Schelter, Eric J.

    2014-06-25

    Electrochemical experiments performed on the complex Ce-IV[2-((BuNO)-Bu-t)py](4), where [2-((BuNO)-Bu-t)py](-) = N-tert-butyl-N-2-pyridylnitroxide, indicate a 2.51 V stabilization of the 4+ oxidation state of Ce compared to [(Bu4N)-Bu-n](2)[Ce(NO3)(6)] in acetonitrile and a 2.95 V stabilization compared to the standard potential for the ion under aqueous conditions. Density functional theory calculations suggest that this preference for the higher oxidation state is a result of the tetrakis(nitroxide) ligand framework at the Ce cation, which allows for effective electron donation into, and partial covalent overlap with, vacant 4f orbitals with delta symmetry. The results speak to the behavior of CeO2 and related solid solutions in oxygen uptake and transport applications, in particular an inherent local character of bonding that stabilizes the 4+ oxidation state. The results indicate a cerium(IV) complex that has been stabilized to an unprecedented degree through tuning of its ligand-field environment.

  17. High-Pressure Reactivity of Kr and F2—Stabilization of Krypton in the +4 Oxidation State

    Directory of Open Access Journals (Sweden)

    Dominik Kurzydłowski

    2017-10-01

    Full Text Available Since the synthesis of the first krypton compound, several other Kr-bearing connections have been obtained. However, in all of them krypton adopts the +2 oxidation state, in contrast to xenon which forms numerous compounds with an oxidation state as high as +8. Motivated by the possibility of thermodynamic stabilization of exotic compounds with the use of high pressure (exceeding 1 GPa = 10 kbar, we present here theoretical investigations into the chemistry of krypton and fluorine at such large compression. In particular we focus on krypton tetrafluoride, KrF4, a molecular crystal in which krypton forms short covalent bonds with neighboring fluorine atoms thus adopting the +4 oxidation state. We find that this hitherto unknown compound can be stabilized at pressures below 50 GPa. Our results indicate also that, at larger compressions, a multitude of other KrmFn fluorides should be stable, among them KrF which exhibits covalent Kr–Kr bonds. Our results set the stage for future high-pressure synthesis of novel krypton compounds.

  18. Image magnification based on similarity analogy

    International Nuclear Information System (INIS)

    Chen Zuoping; Ye Zhenglin; Wang Shuxun; Peng Guohua

    2009-01-01

    Aiming at the high time complexity of the decoding phase in the traditional image enlargement methods based on fractal coding, a novel image magnification algorithm is proposed in this paper, which has the advantage of iteration-free decoding, by using the similarity analogy between an image and its zoom-out and zoom-in. A new pixel selection technique is also presented to further improve the performance of the proposed method. Furthermore, by combining some existing fractal zooming techniques, an efficient image magnification algorithm is obtained, which can provides the image quality as good as the state of the art while greatly decrease the time complexity of the decoding phase.

  19. Effects of Vanadium Ions in Different Oxidation States on Myosin ATPase Extracted from the Solitary Ascidian, Halocynthia roretzi (Drasche) : Biochemistry

    OpenAIRE

    HITOSHI, MICHIBATA; YUTAKA, ZENKO; KENJI, YAMADA; MASATO, HASEGAWA; TATSURO, TERADA; TAKAHARU, NUMAKUANI; Biological Institute, Faculty of Science, Toyama University; Biological Institute, Faculty of Science, Toyama University; Biological Institute, Faculty of Science, Toyama University; Biological Institute, Faculty of Science, Toyama University; Department of Chemistry, Toyama College of Technology; Marine Biological Station, Tohoku University

    1989-01-01

    Some ascidians are known to accumulate vanadium ion within their tissues by 10^6-fold as that in sea water and store the metal ion in its reduced tetravalent and/or trivalent states. It is also well known that phosphoenzymes are inhibited by pentavalent vanadium ion over a range of 10nM to 1mM. In the present experiment we have therefore examined the effects of vanadium ions in different oxidation states on the activity of myosin ATPase extracted from the mantle of the ascidian, Halocynthia r...

  20. Current emission trends for nitrogen oxides, sulfur dioxide, and volatile organic compounds by month and state: Methodology and results

    International Nuclear Information System (INIS)

    Kohout, E.J.; Miller, D.J.; Nieves, L.A.; Rothman, D.S.; Saricks, C.L.; Stodolsky, F.; Hanson, D.A.

    1990-08-01

    This report presents estimates of monthly sulfur dioxide (SO 2 ), nitrogen oxides (NO x ), and nonmethane voltatile organic compound (VOC) emissions by sector, region, and state in the contiguous United States for the years 1975 through 1988. This work has been funded as part of the National Acid Precipitation Assessment Program's Emissions and Controls Task Group by the US Department of Energy (DOE) Office of Fossil Energy (FE). The DOE project officer is Edward C. Trexler, DOE/FE Office of Planning and Environment

  1. Plutonium uptake by the green alga Scenedesmus obliquus (Turp) Kutz, as a function of isotope and oxidation state

    Energy Technology Data Exchange (ETDEWEB)

    Tkacik, M.F.

    1977-01-01

    This study was designed to determine the effect of plutonium chemical valence state on the availability of small concentrations of /sup 238/Pu and /sup 239/Pu to algae. The uptake experiments involved the green alga Scenedesmus obliquus, grown in batch cultures. Plutonium concentrations accumulated by this alga were linearly related to plutonium concentrations. There was no significant difference (rho = 0.05) in algal plutonium accumulations, on a mass basis, of either /sup 238/Pu or /sup 239/Pu in either Pu/sup +4/ or Pu/sup +6/ oxidation state at the concentrations studied.

  2. Plutonium uptake by the green alga Scenedesmus obliquus (Turp) Kutz, as a function of isotope and oxidation state

    International Nuclear Information System (INIS)

    Tkacik, M.F.

    1977-01-01

    This study was designed to determine the effect of plutonium chemical valence state on the availability of small concentrations of 238 Pu and 239 Pu to algae. The uptake experiments involved the green alga Scenedesmus obliquus, grown in batch cultures. Plutonium concentrations accumulated by this alga were linearly related to plutonium concentrations. There was no significant difference (rho = 0.05) in algal plutonium accumulations, on a mass basis, of either 238 Pu or 239 Pu in either Pu +4 or Pu +6 oxidation state at the concentrations studied

  3. Heterometallic molecular precursors for a lithium-iron oxide material: synthesis, solid state structure, solution and gas-phase behaviour, and thermal decomposition.

    Science.gov (United States)

    Han, Haixiang; Wei, Zheng; Barry, Matthew C; Filatov, Alexander S; Dikarev, Evgeny V

    2017-05-02

    Three heterometallic single-source precursors with a Li : Fe = 1 : 1 ratio for a LiFeO 2 oxide material are reported. Heterometallic compounds LiFeL 3 (L = tbaoac (1), ptac (2), and acac(3)) have been obtained on a large scale, in nearly quantitative yields by one-step reactions that employ readily available reagents. The heterometallic precursor LiFe(acac) 3 (3) with small, symmetric substituents on the ligand (acac = pentane-2,4-dionate), maintains a 1D polymeric structure in the solid state that limits its volatility and prevents solubility in non-coordinating solvents. The application of the unsymmetrical ligands, tbaoac (tert-butyl acetoacetate) and ptac (1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedionate), that exhibit different bridging properties at the two ends of the ligand, allowed us to change the connectivity pattern within the heterometallic assembly. The latter was demonstrated by structural characterization of heterometallic complexes LiFe(tbaoac) 3 (1) and LiFe(ptac) 3 (2) that consist of discrete heterocyclic tetranuclear molecules Li 2 Fe 2 L 6 . The compounds are highly volatile and exhibit a congruent sublimation character. DART mass spectrometric investigation revealed the presence of heterometallic molecules in the gas phase. The positive mode spectra are dominated by the presence of [M - L] + peaks (M = Li 2 Fe 2 L 6 ). In accord with their discrete molecular structure, complexes 1 and 2 are highly soluble in nearly all common solvents. In order to test the retention of the heterometallic structure in solution, the diamagnetic analog of 1, LiMg(tbaoac) 3 (4), has been isolated. Its tetranuclear molecular structure was found to be isomorphous to that of the iron counterpart. 1 H and 7 Li NMR spectroscopy unambiguously confirmed the presence of heterometallic molecules in solutions of non-coordinating solvents. The heterometallic precursor 1 was shown to exhibit clean thermal decomposition in air that results in phase-pure

  4. AnalogRF and mixed-signal circuit systematic design

    CERN Document Server

    Tlelo-Cuautle, Esteban; Castro-Lopez, Rafael

    2013-01-01

    Despite the fact that in the digital domain, designers can take full benefits of IPs and design automation tools to synthesize and design very complex systems, the analog designers’ task is still considered as a ‘handcraft’, cumbersome and very time consuming process. Thus, tremendous efforts are being deployed  to develop new design methodologies in the analog/RF and mixed-signal domains. This book collects 16 state-of-the-art contributions devoted to the topic of systematic design of analog, RF and mixed signal circuits. Divided in the two parts Methodologies and Techniques recent theories, synthesis techniques and design methodologies, as well as new sizing approaches in the field of robust analog and mixed signal design automation are presented for researchers and R/D engineers.  

  5. Shock compression of strongly correlated oxides: A liquid-regime equation of state for cerium(IV) oxide

    Science.gov (United States)

    Weck, Philippe F.; Cochrane, Kyle R.; Root, Seth; Lane, J. Matthew D.; Shulenburger, Luke; Carpenter, John H.; Sjostrom, Travis; Mattsson, Thomas R.; Vogler, Tracy J.

    2018-03-01

    The shock Hugoniot for full-density and porous CeO2 was investigated in the liquid regime using ab initio molecular dynamics (AIMD) simulations with Erpenbeck's approach based on the Rankine-Hugoniot jump conditions. The phase space was sampled by carrying out NVT simulations for isotherms between 6000 and 100 000 K and densities ranging from ρ =2.5 to 20 g /cm3 . The impact of on-site Coulomb interaction corrections +U on the equation of state (EOS) obtained from AIMD simulations was assessed by direct comparison with results from standard density functional theory simulations. Classical molecular dynamics (CMD) simulations were also performed to model atomic-scale shock compression of larger porous CeO2 models. Results from AIMD and CMD compression simulations compare favorably with Z-machine shock data to 525 GPa and gas-gun data to 109 GPa for porous CeO2 samples. Using results from AIMD simulations, an accurate liquid-regime Mie-Grüneisen EOS was built for CeO2. In addition, a revised multiphase SESAME-type EOS was constrained using AIMD results and experimental data generated in this work. This study demonstrates the necessity of acquiring data in the porous regime to increase the reliability of existing analytical EOS models.

  6. Plant uptake of americium, curium, and the chemical analog neodymium

    International Nuclear Information System (INIS)

    Weimer, W.C.; Laul, J.C.; Kutt, J.C.; Bondietti, E.A.

    1977-01-01

    The plant uptake from several bulk soils has been determined for neodymium, a chemical analog to the transuranium elements americium and curium, and several other native rare earth elements as well. These investigations have demonstrated that neodymium, which has very similar chemical properties to amercium and curium and should have a similar environmental behavior, does behave indistinguishably under both laboratory and field conditions. The uptake of the weathered or mobile forms of these elements from soils is expected to be governed primarily by their identical oxidation states and nearly identical ionic radii. This hypothesis is strongly supported by the chondritic (primordial) normalized rare earth element patterns in several plants. In these samples, the entire series of rare earth elements behaves as a smooth function of the REE ionic radii, as is also seen in the contiguous soils. This behavior suggests that the plant uptake of other ions with similar chemical properties (i.e., americium and curium) would also be governed by ionic size and charge

  7. Multichannel analog temperature sensing system

    International Nuclear Information System (INIS)

    Gribble, R.

    1985-08-01

    A multichannel system that protects the numerous and costly water-cooled magnet coils on the translation section of the FRX-C/T magnetic fusion experiment is described. The system comprises a thermistor for each coil, a constant current circuit for each thermistor, and a multichannel analog-to-digital converter interfaced to the computer

  8. 49205 ANALOGE OG DIGITALE FILTRE

    DEFF Research Database (Denmark)

    Gaunholt, Hans

    1997-01-01

    Theese lecture notes treats the fundamental theory and the most commonly used design methods for passive- active and digital filters with special emphasis on microelectronic realizations. The lecture notes covers 75% of the material taught in the course 49205 Analog and Digital Filters...

  9. Drawing Analogies to Deepen Learning

    Science.gov (United States)

    Fava, Michelle

    2017-01-01

    This article offers examples of how drawing can facilitate thinking skills that promote analogical reasoning to enable deeper learning. The instructional design applies cognitive principles, briefly described here. The workshops were developed iteratively, through feedback from student and teacher participants. Elements of the UK National…

  10. Signatures of Quantized Energy States in Solution-Processed Ultrathin Layers of Metal-Oxide Semiconductors and Their Devices

    KAUST Repository

    Labram, John G.

    2015-02-13

    Physical phenomena such as energy quantization have to-date been overlooked in solution-processed inorganic semiconducting layers, owing to heterogeneity in layer thickness uniformity unlike some of their vacuum-deposited counterparts. Recent reports of the growth of uniform, ultrathin (<5 nm) metal-oxide semiconductors from solution, however, have potentially opened the door to such phenomena manifesting themselves. Here, a theoretical framework is developed for energy quantization in inorganic semiconductor layers with appreciable surface roughness, as compared to the mean layer thickness, and present experimental evidence of the existence of quantized energy states in spin-cast layers of zinc oxide (ZnO). As-grown ZnO layers are found to be remarkably continuous and uniform with controllable thicknesses in the range 2-24 nm and exhibit a characteristic widening of the energy bandgap with reducing thickness in agreement with theoretical predictions. Using sequentially spin-cast layers of ZnO as the bulk semiconductor and quantum well materials, and gallium oxide or organic self-assembled monolayers as the barrier materials, two terminal electronic devices are demonstrated, the current-voltage characteristics of which resemble closely those of double-barrier resonant-tunneling diodes. As-fabricated all-oxide/hybrid devices exhibit a characteristic negative-differential conductance region with peak-to-valley ratios in the range 2-7.

  11. Bayesian analogy with relational transformations.

    Science.gov (United States)

    Lu, Hongjing; Chen, Dawn; Holyoak, Keith J

    2012-07-01

    How can humans acquire relational representations that enable analogical inference and other forms of high-level reasoning? Using comparative relations as a model domain, we explore the possibility that bottom-up learning mechanisms applied to objects coded as feature vectors can yield representations of relations sufficient to solve analogy problems. We introduce Bayesian analogy with relational transformations (BART) and apply the model to the task of learning first-order comparative relations (e.g., larger, smaller, fiercer, meeker) from a set of animal pairs. Inputs are coded by vectors of continuous-valued features, based either on human magnitude ratings, normed feature ratings (De Deyne et al., 2008), or outputs of the topics model (Griffiths, Steyvers, & Tenenbaum, 2007). Bootstrapping from empirical priors, the model is able to induce first-order relations represented as probabilistic weight distributions, even when given positive examples only. These learned representations allow classification of novel instantiations of the relations and yield a symbolic distance effect of the sort obtained with both humans and other primates. BART then transforms its learned weight distributions by importance-guided mapping, thereby placing distinct dimensions into correspondence. These transformed representations allow BART to reliably solve 4-term analogies (e.g., larger:smaller::fiercer:meeker), a type of reasoning that is arguably specific to humans. Our results provide a proof-of-concept that structured analogies can be solved with representations induced from unstructured feature vectors by mechanisms that operate in a largely bottom-up fashion. We discuss potential implications for algorithmic and neural models of relational thinking, as well as for the evolution of abstract thought. Copyright 2012 APA, all rights reserved.

  12. Crows spontaneously exhibit analogical reasoning.

    Science.gov (United States)

    Smirnova, Anna; Zorina, Zoya; Obozova, Tanya; Wasserman, Edward

    2015-01-19

    Analogical reasoning is vital to advanced cognition and behavioral adaptation. Many theorists deem analogical thinking to be uniquely human and to be foundational to categorization, creative problem solving, and scientific discovery. Comparative psychologists have long been interested in the species generality of analogical reasoning, but they initially found it difficult to obtain empirical support for such thinking in nonhuman animals (for pioneering efforts, see [2, 3]). Researchers have since mustered considerable evidence and argument that relational matching-to-sample (RMTS) effectively captures the essence of analogy, in which the relevant logical arguments are presented visually. In RMTS, choice of test pair BB would be correct if the sample pair were AA, whereas choice of test pair EF would be correct if the sample pair were CD. Critically, no items in the correct test pair physically match items in the sample pair, thus demanding that only relational sameness or differentness is available to support accurate choice responding. Initial evidence suggested that only humans and apes can successfully learn RMTS with pairs of sample and test items; however, monkeys have subsequently done so. Here, we report that crows too exhibit relational matching behavior. Even more importantly, crows spontaneously display relational responding without ever having been trained on RMTS; they had only been trained on identity matching-to-sample (IMTS). Such robust and uninstructed relational matching behavior represents the most convincing evidence yet of analogical reasoning in a nonprimate species, as apes alone have spontaneously exhibited RMTS behavior after only IMTS training. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Electrocatalytic oxidation of methanol by the [Ru3O(OAc6(py2(CH3OH]3+cluster: improving the metal-ligand electron transfer by accessing the higher oxidation states of a multicentered system

    Directory of Open Access Journals (Sweden)

    Henrique E. Toma

    2010-01-01

    Full Text Available The [Ru3O(Ac6(py2(CH3OH]+ cluster provides an effective electrocatalytic species for the oxidation of methanol under mild conditions. This complex exhibits characteristic electrochemical waves at -1.02, 0.15 and 1.18 V, associated with the Ru3III,II,II/Ru3III,III,II/Ru 3III,III,III /Ru3IV,III,III successive redox couples, respectively. Above 1.7 V, formation of two RuIV centers enhances the 2-electron oxidation of the methanol ligand yielding formaldehyde, in agreement with the theoretical evolution of the HOMO levels as a function of the oxidation states. This work illustrates an important strategy to improve the efficiency of the oxidation catalysis, by using a multicentered redox catalyst and accessing its multiple higher oxidation states.

  14. Control of anode supported SOFCs (solid oxide fuel cells): Part I. mathematical modeling and state estimation within one cell

    International Nuclear Information System (INIS)

    Amedi, Hamid Reza; Bazooyar, Bahamin; Pishvaie, Mahmoud Reza

    2015-01-01

    In this paper, a 3-dimensional mathematical model for one cell of an anode-supported SOFC (solid oxide fuel cells) is presented. The model is derived from the partial differential equations representing the conservation laws of ionic and electronic charges, mass, energy, and momentum. The model is implemented to fully characterize the steady state operation of the cell with countercurrent flow pattern of fuel and air. The model is also used for the comparison of countercurrent with concurrent flow patterns in terms of thermal stress (temperature distribution) and quality of operation (current density). Results reveal that the steady-state cell performance curve and output of simulations qualitatively match experimental data of the literature. Results also demonstrate that countercurrent flow pattern leads to an even distribution of temperature, more uniform current density along the cell and thus is more enduring and superior to the concurrent flow pattern. Afterward, the thorough 3-dimensional model is used for state estimation instead of a real cell. To estimate states, the model is simplified and changed to a 1-dimensional model along flow streams. This simplified model includes uncertainty (because of simplifying assumptions of the model), noise, and disturbance (because of measurements). The behaviors of extended and ensemble Kalman filter as an observer are evaluated in terms of estimating the states and filtering the noises. Results demonstrate that, like extended Kalman filter, ensemble Kalman filter properly estimates the states with 20 sets. - Highlights: • A 3-dimensional model for one cell of SOFC (solid oxide fuel cells) is presented. • Higher voltages and thermal stress in countercurrent than concurrent flow pattern. • State estimation of the cell is examined by ensemble and extended Kalman filters. • Ensemble with 20 sets is as good as extended Kalman filter.

  15. Electrode-Impregnable and Cross-Linkable Poly(ethylene oxide)-Poly(propylene oxide)-Poly(ethylene oxide) Triblock Polymer Electrolytes with High Ionic Conductivity and a Large Voltage Window for Flexible Solid-State Supercapacitors.

    Science.gov (United States)

    Han, Jae Hee; Lee, Jang Yong; Suh, Dong Hack; Hong, Young Taik; Kim, Tae-Ho

    2017-10-04

    We present cross-linkable precursor-type gel polymer electrolytes (GPEs) that have large ionic liquid uptake capability, can easily penetrate electrodes, have high ion conductivity, and are mechanically strong as high-performance, flexible all-solid-state supercapacitors (SC). Our polymer precursors feature a hydrophilic-hydrophobic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock main-chain structure and trifunctional silane end groups that can be multi-cross-linked with each other through a sol-gel process. The cross-linked solid-state electrolyte film with moderate IL content (200 wt %) shows a well-balanced combination of excellent ionic conductivity (5.0 × 10 -3 S cm -1 ) and good mechanical stability (maximum strain = 194%). Moreover, our polymer electrolytes have various advantages including high thermal stability (decomposition temperature > 330 °C) and the capability to impregnate electrodes to form an excellent electrode-electrolyte interface due to the very low viscosity of the precursors. By assembling our GPE-impregnated electrodes and solid-state GPE film, we demonstrate an all-solid-state SC that can operate at 3 V and provides an improved specific capacitance (112.3 F g -1 at 0.1 A g -1 ), better rate capability (64% capacity retention until 20 A g -1 ), and excellent cycle stability (95% capacitance decay over 10 000 charge/discharge cycles) compared with those of a reference SC using a conventional PEO electrolyte. Finally, flexible SCs with a high energy density (22.6 W h kg -1 at 1 A g -1 ) and an excellent flexibility (>93% capacitance retention after 5000 bending cycles) can successfully be obtained.

  16. Neutron-skin thickness from the study of the anti-analog giant dipole resonance

    NARCIS (Netherlands)

    Krasznahorkay, A.; Stuhl, L.; Csatlós, M.; Algora, A.; Gulyás, J.; Timár, J.; Paar, N.; Vretenar, D.; Boretzky, K.; Heil, M.; Litvinov, Yu A.; Rossi, D.; Scheidenberger, C.; Simon, H.; Weick, H.; Bracco, A.; Brambilla, S.; Blasi, N.; Camera, F.; Giaz, A.; Million, B.; Pellegri, L.; Riboldi, S.; Wieland, O.; Altstadt, S.; Fonseca, M.; Glorius, J.; Göbel, K.; Heftrich, T.; Koloczek, A.; Kräckmann, S.; Langer, C.; Plag, R.; Pohl, M.; Rastrepina, G.; Reifarth, R.; Schmidt, S.; Sonnabend, K.; Weigand, M.; Harakeh, M. N.; Kalantar-Nayestanaki, N.; Rigollet, C.; Bagchi, S.; Najafi, M. A.; Aumann, T.; Atar, L.; Heine, M.; Holl, M.; Movsesyan, A.; Schrock, P.; Volkov, V.; Wamers, F.; Fiori, E.; Löher, B.; Marganiec, J.; Savran, D.; Johansson, H. T.; Fernández, P. Diaz; Garg, U.; Balabanski, D. L.

    2012-01-01

    The gamma-decay of the anti-analog of the giant dipole resonance (AGDR) has been measured to the isobaric analog state excited in the p(124Sn,n) reaction at a beam energy of 600 MeV/nucleon. The energy of the transition was also calculated with state-of-the-art self-consistent random-phase

  17. Transistor analogs of emergent iono-neuronal dynamics.

    Science.gov (United States)

    Rachmuth, Guy; Poon, Chi-Sang

    2008-06-01

    Neuromorphic analog metal-oxide-silicon (MOS) transistor circuits promise compact, low-power, and high-speed emulations of iono-neuronal dynamics orders-of-magnitude faster than digital simulation. However, their inherently limited input voltage dynamic range vs power consumption and silicon die area tradeoffs makes them highly sensitive to transistor mismatch due to fabrication inaccuracy, device noise, and other nonidealities. This limitation precludes robust analog very-large-scale-integration (aVLSI) circuits implementation of emergent iono-neuronal dynamics computations beyond simple spiking with limited ion channel dynamics. Here we present versatile neuromorphic analog building-block circuits that afford near-maximum voltage dynamic range operating within the low-power MOS transistor weak-inversion regime which is ideal for aVLSI implementation or implantable biomimetic device applications. The fabricated microchip allowed robust realization of dynamic iono-neuronal computations such as coincidence detection of presynaptic spikes or pre- and postsynaptic activities. As a critical performance benchmark, the high-speed and highly interactive iono-neuronal simulation capability on-chip enabled our prompt discovery of a minimal model of chaotic pacemaker bursting, an emergent iono-neuronal behavior of fundamental biological significance which has hitherto defied experimental testing or computational exploration via conventional digital or analog simulations. These compact and power-efficient transistor analogs of emergent iono-neuronal dynamics open new avenues for next-generation neuromorphic, neuroprosthetic, and brain-machine interface applications.

  18. State of dog's metabolism in the remote period after the oxide tritium influence

    International Nuclear Information System (INIS)

    Kalistratova, V.S.; Tishchenko, G.S.; Bortnik, L.A.; Nisimov, P.G.; Romanova, I.B.

    2000-01-01

    Influence of tritium oxide on the metabolism by some indices of lipid metabolism (common lipids, β-lipoproteins, cholesterin), protein metabolism (cholinesterase) and carbohydrate metabolism (blood sugar) was studied. It was established that the introduction into organism of tritium oxide in the quantities, which could form lethal and sublethal doses of internal radiation, provoked the main changes of values of mentioned indices of metabolism. The character of metabolism changes in the remote period allows to judge about the development of sclerosis processes which can be the result of radiation-stipulated acceleration of organism aging [ru

  19. Enhanced catalytic hydrogenation activity of Ni/reduced graphene oxide nanocomposite prepared by a solid-state method

    Science.gov (United States)

    Li, Yizhao; Cao, Yali; Jia, Dianzeng

    2018-01-01

    A simple solid-state method has been applied to synthesize Ni/reduced graphene oxide (Ni/rGO) nanocomposite under ambient condition. Ni nanoparticles with size of 10-30 nm supported on reduced graphene oxide (rGO) nanosheets are obtained through one-pot solid-state co-reduction among nickel chloride, graphene oxide, and sodium borohydride. The Ni/rGO nanohybrid shows enhanced catalytic activity toward the reduction of p-nitrophenol (PNP) into p-aminophenol compared with Ni nanoparticles. The results of kinetic research display that the pseudo-first-order rate constant for hydrogenation reaction of PNP with Ni/rGO nanocomposite is 7.66 × 10-3 s-1, which is higher than that of Ni nanoparticles (4.48 × 10-3 s-1). It also presents superior turnover frequency (TOF, 5.36 h-1) and lower activation energy ( E a, 29.65 kJ mol-1) in the hydrogenation of PNP with Ni/rGO nanocomposite. Furthermore, composite catalyst can be magnetically separated and reused for five cycles. The large surface area and high electron transfer property of rGO support are beneficial for good catalytic performance of Ni/rGO nanocomposite. Our study demonstrates a simple approach to fabricate metal-rGO heterogeneous nanostructures with advanced functions.

  20. Repository-analog experiments of nuclear waste leaching and migration

    International Nuclear Information System (INIS)

    Seitz, M.G.

    1982-01-01

    The potential for radionuclide migration from a breached nuclear-waste repository depends on the leaching and subsequent interaction of the leached radionuclides with materials in the groundwater flow path. An attempt is made to consider all interactions using experiments that integrate repository materials. Results of a repository-analog experiment using borosilicate glass, fissured granite, and flowing water suggest: (1) plutonium was immobile possibly because of its low solubility; (2) caesium migrated down slowly because of sorption; and (3) neptunium remained oxidized even in water of low oxidation potential. By summing the effects of all interactions, not just sorption, the repository-analog experiment produced radionuclide migration that could be expected from a breached repository. (author)

  1. The state-of-the-art and prospects of the oxidation titration method for the determination of uranium in geological samples

    International Nuclear Information System (INIS)

    Sun Jiayan

    1986-01-01

    The state-of-the-art of the oxidation titration method for the determination of uranium in geological samples is reviewed in some respects such as the prereduction of U(VI), oxidation of U(IV) and the detection of the end-point. Comments are also made on the prospects of further improvements of this method

  2. Example of uranium(IV) insertion within a macrocyclic crown ether with coexistence of the metal in two oxidation states

    Energy Technology Data Exchange (ETDEWEB)

    Bombieri, G; De Paoli, G [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi; Immirzi, A

    1978-01-01

    Reaction of UCl/sub 4/ with 18-crown-6 in tetrahydrofuran yields (UCl/sub 4/)/sub 3/ (18-crown-6)/sub 2/ which on recrystallization in nitromethane, gives a partially oxidized and hydrolyzed product whose structure has been investigated by X-ray diffraction. The compound crystallizes in the orthorhombic system. The cell contains eight UCl/sub 3//sup +/ cations each inserted within a crown molecule and four (UO/sub 2/Cl/sub 3/(OH)(H/sub 2/O))/sup 2 -/anions having a pentagonal bipyramidal structure. Four solvated nitromethane molecules are also present. The compound represents one of the very few examples in which uranium exists in two oxidation states, and the first example in which its insertion within a crown macrocycle has been proved by an X-ray diffraction study.

  3. Remote mixed oxide fabrication facility development. Volume 2. State-of-the-art review of remote maintenance system technology

    International Nuclear Information System (INIS)

    Horgos, R.M.; Masch, M.L.

    1979-06-01

    This report provides a state-of-the-art review of remote systems technology, which includes manipulators, process connectors, vision systems and specialized process systems. A proposed mixed oxide fuel fabrication facility was reviewed and evaluated for identification of major remote maintenance and repair tasks. The technological areas were evaluated on the basis of their suitability or applicability for remote maintenance and repair of a proposed fully remote operating mixed oxide fuel fabrication facility. A technological base exists from which the design criteria for a reliable, remote operating facility can be established. Commercially available systems and components, along with those remote technologies now in development, will require modifications to adapt them to specific plant designs and requirements

  4. Electrochemistry and time dependent DFT study of a (vinylenedithio)-TTF derivative in different oxidation states

    NARCIS (Netherlands)

    Halpin, Yvonne; Schulz, Martin; Brooks, Andrew C.; Browne, Wesley R.; Wallis, John D.; Gonzalez, Leticia; Day, Peter; Vos, Johannes G.

    2013-01-01

    The electrochemical and spectroelectrochemical properties of a bis-pyrid-4-yl functionalised vinylenedithio-TFF derivative, 1, in solution are reported. The compound was immobilised on a Pt electrode and the resulting layers formed were investigated using electrochemical techniques. Two oxidation

  5. The state of permanganate with relation to in situ chemical oxidation

    International Nuclear Information System (INIS)

    Veronda, Brenda; Dingens, Matthew

    2007-01-01

    In Situ Chemical Oxidation (ISCO) with permanganate had its beginnings over 10 years ago. Since that time, many sites have been successfully treated for organic compounds including chlorinated ethenes (perchloroethylene, trichloroethylene, etc.) phenols, explosives such as RDX, and many other organics. The successful application of ISCO with permanganate requires the integration of many site-specific factors into the remedial design. ISCO with permanganate is an effective technology, not only for its oxidative properties and persistence, but also for its application flexibility to remediate soil and groundwater. The merits of any type of treatment technology can be assessed in terms of effectiveness, ease of use, reaction rate, and cost. The use of permanganate for in situ chemical oxidation results in the complete mineralization of TCE and PCE and can result in treatment levels below detection limits. Permanganate is a single component oxidizer, which is easily handled, mixed and distributed to the subsurface. Permanganate is also inexpensive to design and implement as compared to other technologies. This presentation will provide a general overview of the application and safety aspects of ISCO with permanganate. This paper will discuss the advantages and limitations of this technology, typical cost ranges, site evaluation and application technologies. (authors)

  6. Influence of Structure and Charge State on the Mechanism of CO Oxidation on Gold Clusters

    Science.gov (United States)

    Johnson, Grant; Burgel, Christian; Reilly, Nelly; Mitric, Roland; Kimble, Michele; Tyo, Eric; Castleman, A. W.; Bonacic-Koutecky, Vlasta

    2008-05-01

    Gas-phase reactivity experiments and high level theoretical calculations have been employed to study the interaction of both positively and negatively charged gold oxide clusters with carbon monoxide (CO). We demonstrate that for negatively charged clusters CO is oxidized to CO2 by an Eley-Ridel-like (ER-) mechanism involving the attack of CO on oxygen rather than gold. In contrast, for positively charged clusters, the oxidation reaction may also occur by a Langmuir-Hinshelwood-like (LH-) mechanism involving the initial binding of CO to a gold atom followed by subsequent migration to an oxygen site. The LH mechanism is made possible through the large energy gain associated with the adsorption of two CO molecules onto cationic gold clusters. Structure-reactivity relationships are also established which demonstrate that terminally bound oxygen atoms are the most active sites for CO oxidation. Bridge bonded oxygen atoms and molecularly bound O2 units are shown to be inert. We also establish an inverse relationship between the binding energy of CO to gold clusters and the energy of the clusters lowest unoccupied molecular orbital (LUMO).

  7. A heat exchanger analogy of automotive paint ovens

    International Nuclear Information System (INIS)

    Rao, Preetham P.

    2013-01-01

    Computational prediction of vehicle temperatures in an automotive paint oven is essential to predict paint quality and manufacturability. The complex geometry of vehicles, varying scales in the flow, transient nature of the process, and the tightly coupled conjugate heat transfer render the numerical models computationally very expensive. Here, a novel, simplified model of the oven is developed using an analogy to a three-stream cross flow heat exchanger that transfers heat from air to a series of moving bodies and supporting carriers. The analogous heat exchanger equations are developed and solved numerically. Steady state Computational Fluid Dynamics (CFD) simulations are carried out to model the flow field and to extract the heat transfer coefficients around the body and carriers. The air temperature distribution from the CFD models is used as a boundary condition in the analogous model. Correction coefficients are used in the analogy to take care of various assumptions. These are determined from existing test data. The same corrections are used to predict air temperatures for a modified configuration of the oven and a different vehicle. The method can be used to conduct control volume analysis of ovens to determine energy efficiency, and to study new vehicle or oven designs. -- Highlights: • Analogy of an automotive paint oven as a three stream cross flow heat exchanger. • The three streams are vehicle bodies, carriers and hot air. • Convection coefficients and inlet air stream temperatures from steady CFD simulations. • Analogy useful for overall energy efficiency analysis of conveyor ovens in general

  8. A study of relaxation mechanisms in the A{sup 2}{Sigma}{sup +} state of nitric oxide by time resolved double resonant polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stampanoni-Panariello, A; Bombach, R; Hemmerling, B; Hubschmid, W [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    Double resonant polarization labeling spectroscopy is applied to detect nitric oxide in flames and to characterize rotational energy transfer and orientation changing collisions in its first excited electronic state. (author) 4 figs., 3 refs.

  9. Analog circuit design art, science and personalities

    CERN Document Server

    Williams, Jim

    1991-01-01

    This book is far more than just another tutorial or reference guide - it's a tour through the world of analog design, combining theory and applications with the philosophies behind the design process. Readers will learn how leading analog circuit designers approach problems and how they think about solutions to those problems. They'll also learn about the `analog way' - a broad, flexible method of thinking about analog design tasks.A comprehensive and useful guide to analog theory and applications. Covers visualizing the operation of analog circuits. Looks at how to rap

  10. A detailed study on the transition from the blocked to the superparamagnetic state of reduction-precipitated iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Witte, K.; Bodnar, W.; Mix, T.; Schell, N.; Fulda, G.; Woodcock, T.G.; Burkel, E.

    2016-01-01

    Magnetic iron oxide nanoparticles were prepared by salt-assisted solid-state chemical precipitation method with alternating fractions of the ferric iron content. The physical properties of the precipitated nanoparticles mainly consisting of magnetite were investigated by means of transmission electron microscopy, high energy X-ray diffraction, vibrating sample magnetometry and Mössbauer spectroscopy. With particle sizes ranging from 16.3 nm to 2.1 nm, a gradual transition from the blocked state to the superparamagnetic state was observed. The transition was described as a dependence of the ferric iron content used during the precipitation. Composition, mean particle size, coercivity, saturation polarisation, as well as hyperfine interaction parameters and their evolution were studied systematically over the whole series of iron oxide nanoparticles. - Highlights: • Study of superparamagnetic transition of magnetite varying ferric iron content. • Coercivity is mainly influenced by the particle size. • Saturation polarisation influenced by the goethite content and the particle size. • Number of vacancies tend to increase with increasing ferric iron content. • Fe 3 O 4 B-sites are stronger effected by the reduction of particle size than A-sites.

  11. All-solid-state flexible microsupercapacitors based on reduced graphene oxide/multi-walled carbon nanotube composite electrodes

    Science.gov (United States)

    Mao, Xiling; Xu, Jianhua; He, Xin; Yang, Wenyao; Yang, Yajie; Xu, Lu; Zhao, Yuetao; Zhou, Yujiu

    2018-03-01

    All-solid-state flexible microsupercapacitors have been intensely investigated in order to meet the rapidly growing demands for portable microelectronic devices. Herein, we demonstrate a facile, readily scalable and cost-effective laser induction process for preparing reduced graphene oxide/multi-walled carbon nanotube composite, which can be used as the interdigital electrodes in microsupercapacitors. The obtained composite exhibits high volumetric capacitance about 49.35 F cm-3, which is nearly 5 times higher than that of the pristine reduced graphene oxide film in aqueous 1.0 M H2SO4 solution (measured at a current density of 5 A cm-3 in a three-electrode testing). Additionally, an all-solid-state flexible microsupercapacitor employing these composite electrodes with PVA/H3PO4 gel electrolyte delivers high volumetric energy density of 6.47 mWh cm-3 at 10 mW cm-3 under the current density of 20 mA cm-3 as well as achieve excellent cycling stability retaining 88.6% of its initial value and outstanding coulombic efficiency after 10,000 cycles. Furthermore, the microsupercapacitors array connected in series/parallel can be easily adjusted to achieve the demands in practical applications. Therefore, this work brings a promising new candidate of prepare technologies for all-solid-state flexible microsupercapacitors as miniaturized power sources used in the portable and wearable electronics.

  12. Effect of charged deep states in hydrogenated amorphous silicon on the behavior of iron oxides nanoparticles deposited on its surface

    International Nuclear Information System (INIS)

    Gmucova, Katarina; Weis, Martin; Nadazdy, Vojtech; Capek, Ignac; Satka, Alexander; Chitu, Livia; Cirak, Julius; Majkova, Eva

    2008-01-01

    Langmuir-Blodgett technique has been used for the deposition of ordered two-dimensional arrays of iron oxides (Fe 3 O 4 /Fe 2 O 3 ) nanoparticles onto the photovoltaic hydrogenated amorphous silicon (a-Si:H) thin film. Electric field at the a-Si:H/iron oxides nanoparticles interface was directly in the electrochemical cell modified by light soaking and bias voltage (negative or positive) pretreatment resulting in the change of the dominant type of charged deep states in the a-Si:H layer. Induced reversible changes in the nanoparticle redox behavior have been observed. We suggest two possible explanations of the data obtained, both of them are needed to describe measured electrochemical signals. The first one consists in the electrocatalytical effect caused by the defect states (negatively or positively charged) in the a-Si:H layer. The second one consists in the possibility to manipulate the nanoparticle cores in the prepared structure immersed in aqueous solution via the laser irradiation under specific bias voltage. In this case, the nanoparticle cores are assumed to be covered with surface clusters of heterovalent complexes created onto the surface regions with prevailing ferrous or ferric valency. Immersed in the high viscosity surrounding composed of the wet organic nanoparticle envelope these cores are able to perform a field-assisted pivotal motion. The local electric field induced by the deep states in the a-Si:H layer stabilizes their 'orientation ordering' in an energetically favourable position

  13. Analogies between antiferromagnets and antiferroelectrics

    International Nuclear Information System (INIS)

    Enz, C.P.; Matthias, B.T.

    1980-01-01

    Ferro- and antiferromagnetism in the Laves phase TiBesub(2-x) Cusub(x) occurs for 0.1 4 H 2 PO 4 and its solid solutions with TlH 2 PO 4 and with the ferroelectric KH 2 PO 4 are discussed as function of deuteration and of pressure. Another analogy as function of pressure is established with the antiferroelectric perovskite PbZrO 3 . (author)

  14. Novel phosphanucleoside analogs of dideoxynucleosides

    Czech Academy of Sciences Publication Activity Database

    Páv, Ondřej; Buděšínský, Miloš; Rosenberg, Ivan

    2017-01-01

    Roč. 73, č. 34 (2017), s. 5220-5228 ISSN 0040-4020 R&D Projects: GA ČR(CZ) GA17-12703S; GA ČR GA13-26526S; GA MZd NV15-31604A Institutional support: RVO:61388963 Keywords : phosphanucleoside * nucleoside analog * ring-closing metathesis * stereoselective hydroboration * chiral resolution Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 2.651, year: 2016

  15. Hemoglobin redux: combining neutron and X-ray diffraction with mass spectrometry to analyse the quaternary state of oxidized hemoglobins

    Energy Technology Data Exchange (ETDEWEB)

    Mueser, Timothy C., E-mail: timothy.mueser@utoledo.edu; Griffith, Wendell P. [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States); Kovalevsky, Andrey Y. [Bioscience Division, MS M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Guo, Jingshu; Seaver, Sean [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States); Langan, Paul [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States); Bioscience Division, MS M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hanson, B. Leif [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States)

    2010-11-01

    X-ray and neutron diffraction studies of cyanomethemoglobin are being used to evaluate the structural waters within the dimer–dimer interface involved in quaternary-state transitions. Improvements in neutron diffraction instrumentation are affording the opportunity to re-examine the structures of vertebrate hemoglobins and to interrogate proton and solvent position changes between the different quaternary states of the protein. For hemoglobins of unknown primary sequence, structural studies of cyanomethemoglobin (CNmetHb) are being used to help to resolve sequence ambiguity in the mass spectra. These studies have also provided additional structural evidence for the involvement of oxidized hemoglobin in the process of erythrocyte senescence. X-ray crystal studies of Tibetan snow leopard CNmetHb have shown that this protein crystallizes in the B state, a structure with a more open dyad, which possibly has relevance to RBC band 3 protein binding and erythrocyte senescence. R-state equine CNmetHb crystal studies elaborate the solvent differences in the switch and hinge region compared with a human deoxyhemoglobin T-state neutron structure. Lastly, comparison of histidine protonation between the T and R state should enumerate the Bohr-effect protons.

  16. Electrostatic analogy for symmetron gravity

    Science.gov (United States)

    Ogden, Lillie; Brown, Katherine; Mathur, Harsh; Rovelli, Kevin

    2017-12-01

    The symmetron model is a scalar-tensor theory of gravity with a screening mechanism that suppresses the effect of the symmetron field at high densities characteristic of the Solar System and laboratory scales but allows it to act with gravitational strength at low density on the cosmological scale. We elucidate the screening mechanism by showing that in the quasistatic Newtonian limit there are precise analogies between symmetron gravity and electrostatics for both strong and weak screening. For strong screening we find that large dense bodies behave in a manner analogous to perfect conductors in electrostatics. Based on this analogy we find that the symmetron field exhibits a lightning rod effect wherein the field gradients are enhanced near the ends of pointed or elongated objects. An ellipsoid placed in a uniform symmetron gradient is shown to experience a torque. By symmetry there is no gravitational torque in this case. Hence this effect unmasks the symmetron and might serve as the basis for future laboratory experiments. The symmetron force between a point mass and a large dense body includes a component corresponding to the interaction of the point mass with its image in the larger body. None of these effects have counterparts in the Newtonian limit of Einstein gravity. We discuss the similarities between symmetron gravity and the chameleon model as well as the differences between the two.

  17. Nitric oxide in plants: an assessment of the current state of knowledge

    DEFF Research Database (Denmark)

    Mur, Luis A J; Mandon, Julien; Persijn, Stefan

    2013-01-01

    Background and aims After a series of seminal works during the last decade of the 20th century nitric oxide (NO) is now firmly placed in the pantheon of plant signals. NO acts in plant-microbe interactions, responses to abiotic stress, stomatal regulation and a range of developmental processes...... of NO production from DEANO (diethylamine nitric oxide), S-nitrosoglutathione (GSNO) and sodium nitroprusside (SNP) following infiltration of tobacco leaves which could aid workers in their experiments. Further, based on current data it is difficult to define a bespoke plant NO signalling pathway, but rather....... By considering the recent advances in plant NO biology, this review will highlight certain key aspects that require further attention. Scope and conclusions The following questions will be considered. Whilst cytosolic nitrate reductase is an important source of NO, the contributions of other mechanisms...

  18. The discrimination of the oxidation states of neptunium in sodium hydroxide solutions by means of chromatography on alumina

    International Nuclear Information System (INIS)

    Shiokawa, Yoshinobu; Yamana, Hajimu; Sato, Akiko; Suzuki, Shin

    1982-01-01

    A method of discriminating the oxidation states of Np in a NaOH solution by means of chromatography on alumina is proposed. In a NaOH solution of 0.5 - 1.7 M (1 M = 1 mol dm - 3 ), the separation of Np (VI) from Np (VII) can be made effectively by means of chromatography on alumina. Only a little Np (VI) is adsorbed on alumina the Np (VII) adsorbed to some extent, and the Np (V), strongly, under the same conditions. By applying this chromatographic method, the method of preparing Np (VI) and Np (VII) of a tracer quantity in 1 M NaOH is established. (author)

  19. Solid-state Water-mediated Transport Reduction of Nanostructured Iron Oxides

    International Nuclear Information System (INIS)

    Smirnov, Vladimir M.; Povarov, Vladimir G.; Voronkov, Gennadii P.; Semenov, Valentin G.; Murin, Igor' V.; Gittsovich, Viktor N.; Sinel'nikov, Boris M.

    2001-01-01

    The Fe 2+ /Fe 3+ ratio in two-dimensional iron oxide nanosructures (nanolayers with a thickness of 0.3-1.5 nm on silica surface) may be precisely controlled using the transport reduction (TR) technique. The species ≡-O-Fe(OH) 2 and (≡Si-O-) 2 -FeOH forming the surface monolayer are not reduced at 400-600 deg. C because of their covalent bonding to the silica surface, as demonstrated by Moessbauer spectroscopy. Iron oxide microparticles (microstructures) obtained by the impregnation technique, being chemically unbound to silica, are subjected to reduction at T ≥ 500 deg. C with formation of metallic iron in the form of α-Fe. Transport reduction of supported nanostructures (consisting of 1 or 4 monolayers) at T ≥ 600 deg. C produces bulk iron(II) silicate and metallic iron phases. The structural-chemical transformations occurring in transport reduction of supported iron oxide nanolayers are proved to be governed by specific phase processes in the nanostructures themselves

  20. Constitutively elevated salicylic acid levels alter photosynthesis and oxidative state but not growth in transgenic populus.

    Science.gov (United States)

    Xue, Liang-Jiao; Guo, Wenbing; Yuan, Yinan; Anino, Edward O; Nyamdari, Batbayar; Wilson, Mark C; Frost, Christopher J; Chen, Han-Yi; Babst, Benjamin A; Harding, Scott A; Tsai, Chung-Jui

    2013-07-01

    Salicylic acid (SA) has long been implicated in plant responses to oxidative stress. SA overproduction in Arabidopsis thaliana leads to dwarfism, making in planta assessment of SA effects difficult in this model system. We report that transgenic Populus tremula × alba expressing a bacterial SA synthase hyperaccumulated SA and SA conjugates without negative growth consequences. In the absence of stress, endogenously elevated SA elicited widespread metabolic and transcriptional changes that resembled those of wild-type plants exposed to oxidative stress-promoting heat treatments. Potential signaling and oxidative stress markers azelaic and gluconic acids as well as antioxidant chlorogenic acids were strongly coregulated with SA, while soluble sugars and other phenylpropanoids were inversely correlated. Photosynthetic responses to heat were attenuated in SA-overproducing plants. Network analysis identified potential drivers of SA-mediated transcriptome rewiring, including receptor-like kinases and WRKY transcription factors. Orthologs of Arabidopsis SA signaling components NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES1 and thioredoxins were not represented. However, all members of the expanded Populus nucleoredoxin-1 family exhibited increased expression and increased network connectivity in SA-overproducing Populus, suggesting a previously undescribed role in SA-mediated redox regulation. The SA response in Populus involved a reprogramming of carbon uptake and partitioning during stress that is compatible with constitutive chemical defense and sustained growth, contrasting with the SA response in Arabidopsis, which is transient and compromises growth if sustained.

  1. Molecular beam epitaxy growth of niobium oxides by solid/liquid state oxygen source and lithium assisted metal-halide chemistry

    Science.gov (United States)

    Tellekamp, M. Brooks; Greenlee, Jordan D.; Shank, Joshua C.; Doolittle, W. Alan

    2015-09-01

    In order to consistently grow high quality niobium oxides and lithium niobium oxides, a novel solid/liquid state oxygen source, LiClO4, has been implemented in a molecular beam epitaxy (MBE) system. LiClO4 is shown to decompose into both molecular and atomic oxygen upon heating. This allows oxidation rates similar to that of molecular oxygen but at a reduced overall beam flux, quantified by in situ Auger analysis. LiClO4 operation is decomposition limited to less than 400 °C, and other material limitations are identified. The design of a custom near-ambient NbCl5 effusion cell is presented, which improves both short and long term stability. Films of Nb oxidation state +2, +3, and +5 are grown using these new tools, including the multi-functional sub-oxide LiNbO2.

  2. The Development of Analogical Reasoning Processes.

    Science.gov (United States)

    Sternberg, Robert J.; Rifkin, Bathsheva

    1979-01-01

    Two experiments were conducted to test the generalizability to children of a theory of analogical reasoning processes, originally proposed for adults, and to examine the development of analogical reasoning processes in terms of five proposed sources of cognitive development. (MP)

  3. 16-channel analog store and multiplexer unit

    Energy Technology Data Exchange (ETDEWEB)

    Brossard, M; Kulka, Z [Clermont-Ferrand-2 Univ., 63 - Aubiere (France). Lab. de Physique Corpusculaire

    1979-03-15

    A 16-channel analog store and multiplexer unit is described. The unit enables storing and selection of analog information which is then digitally encoded by single ADC. This solution becomes economically attractive particularly in multidetector pulse height analysis systems.

  4. Determination of the specific surface energy of oxides and glasses in the solid-state

    International Nuclear Information System (INIS)

    Andryushechkin, S.; Karpman, M.

    2000-01-01

    The production and application of coatings on glasses are used widely in technology. The coatings on glass are used for the regulation of optical, decorative, conducting and other technological and physical properties of glass. In particular, it is important to mention the application of glass fibres for the development of composite materials. However, the specific surface energy of glass and, consequently, its adhesion characteristics are relatively low. The values of these characteristics can be changed by the application of different metallic and nonmetallic coatings is characterised by high surface energy. To produce metallic coatings with the required adhesion strength of glass, it is necessary to have information on the specific surface energy of inorganic glass of different chemical composition. The determination of the relationships between the properties and composition of glass is one of the fundamental problems. At present, a large amount of investigations have been carried out into the investigations of the properties of glass in relation to its composition. However, the problem of establishment of relationships between the properties and composition of glass are especially difficult when examining multicomponent systems (technical glass). It is therefore, in to analyse in each case the properties of not the entire system has a whole but the variation of the properties with temperature of the individual components included in the system, the subsequent application of the additivity principle. The large majority of the glasses represent combinations of oxides of the elements of groups I-III and oxides of the transition metals, forming the mixtures, solid solutions of chemical compounds in the glass production process. Thus, analysis of the characteristics of oxides of the alkali, alkali-earth and transition metals makes it possible to obtain initial data for the evaluation of the surface energy, density, molecular mass of glass containing these oxides

  5. Iron oxides as pedoenvironmental indicators: state of the art, answers and questions (Philippe Duchaufour Medal Lecture)

    Science.gov (United States)

    Torrent, J.

    2012-04-01

    The colour and magnetic properties of soils largely reflect the content and mineralogy of their iron oxides, which in turn relate to the physical, chemical and biological characteristics of the soil environment. For more than 50 years, soil mineralogists and chemists have collected data for iron oxides in soils formed in widely different environments and tried to understand the complex nature of the different suites and formation pathways for these minerals via laboratory experiments. The discovery of ferrihydrite —the poorly crystalline precursor of most Fe oxides— in 1971, and the recognition of its common presence in soils, raised interest in deciphering the environmental factors that affect its transformation into goethite and hematite, the two most abundant crystalline iron oxides in soil. Field observations were consistent with laboratory experiments in which temperature, water activity, pH, foreign ions and organic matter were found to play a key role in the crystallization of ferrihydrite. Thus, the hematite/(hematite + goethite) ratio increased with increasing temperature and also with the likelihood of seasonal soil drying. Exploiting this ratio as a (pedo)environment indicator is, however, not devoid of problems derived from insufficient knowledge of the interactions between the influential chemical variables, difficulties in quantifying the two minerals and changes brought about by reductive dissolution. Soil formation usually leads to magnetic enhancement as a result of the production of magnetite and/or maghemite, which are ferrimagnetic iron oxides, and, possibly, an ordered ferrimagnetic ferrihydrite, as suggested by recent laboratory experiments. The concentration of pedogenic ferrimagnets as estimated via proxies such as magnetic susceptibility or frequency-dependent magnetic susceptibility has been found to relate to climate variables [particularly (paleo)rainfall] in many studies reported over the last 30 years. However, extracting accurate

  6. Analyzer for measurement of nitrogen oxide concentration by ozone content reduction in gas using solid state chemiluminescent sensor

    Science.gov (United States)

    Chelibanov, V. P.; Ishanin, G. G.; Isaev, L. N.

    2014-05-01

    Role of nitrogen oxide in ambient air is described and analyzed. New method of nitrogen oxide concentration measurement in gas phase is suggested based on ozone concentration measurement with titration by nitrogen oxide. Research of chemiluminescent sensor composition is carried out on experimental stand. The sensor produced on the base of solid state non-activated chemiluminescent composition is applied as ozone sensor. Composition is put on the surface of polymer matrix with developed surface. Sensor compositions includes gallic acid with addition of rodamine-6G. Model of interaction process between sensor composition and ozone has been developed, main products appeared during reaction are identified. The product determining the speed of luminescense appearance is found. This product belongs to quinone class. Then new structure of chemiluminescent composition was suggested, with absence of activation period and with high stability of operation. Experimental model of gas analyzer was constructed and operation algorithm was developed. It was demonstrated that developed NO measuring instrument would be applied for monitoring purposes of ambient air. This work was partially financially supported by Government of Russian Federation, Grant 074-U01

  7. Atheism and Analogy: Aquinas Against the Atheists

    OpenAIRE

    Linford, Daniel J.

    2014-01-01

    In the 13th century, Thomas Aquinas developed two models for how humans may speak of God - either by the analogy of proportion or by the analogy of proportionality. Aquinas's doctrines initiated a theological debate concerning analogy that spanned several centuries. In the 18th century, there appeared two closely related arguments for atheism which both utilized analogy for their own purposes. In this thesis, I show that one argument, articulated by the French materialist Paul-Henri Thiry Bar...

  8. Enhancing programming logic thinking using analogy mapping

    Science.gov (United States)

    Sukamto, R. A.; Megasari, R.

    2018-05-01

    Programming logic thinking is the most important competence for computer science students. However, programming is one of the difficult subject in computer science program. This paper reports our work about enhancing students' programming logic thinking using Analogy Mapping for basic programming subject. Analogy Mapping is a computer application which converts source code into analogies images. This research used time series evaluation and the result showed that Analogy Mapping can enhance students' programming logic thinking.

  9. Oxidation states by X-ray fluorescence and electron probe microanalysis techniques

    International Nuclear Information System (INIS)

    Vazquez, Cristina; Riveros, J.A.

    1987-01-01

    Many years ago, several studies showed the effect of a chemical state in X-ray spectra. The effect, however, has rarely been utilized in quantitative chemical analysis. The purpose of this work is to show observed shifts due to different chemical states in iron compounds. (Author) [es

  10. Analogies and the 5E Model

    Science.gov (United States)

    Orgill, Mary Kay; Thomas, Megan

    2007-01-01

    Science classes are full of abstract or challenging concepts that are easier to understand if an analogy is used to illustrate the points. Effective analogies motivate students, clarify students' thinking, help students overcome misconceptions, and give students ways to visualize abstract concepts. When they are used appropriately, analogies can…

  11. Science Teachers' Analogical Reasoning

    Science.gov (United States)

    Mozzer, Nilmara Braga; Justi, Rosária

    2013-01-01

    Analogies can play a relevant role in students' learning. However, for the effective use of analogies, teachers should not only have a well-prepared repertoire of validated analogies, which could serve as bridges between the students' prior knowledge and the scientific knowledge they desire them to understand, but also know how to…

  12. The Micro-Category Account of Analogy

    Science.gov (United States)

    Green, Adam E.; Fugelsang, Jonathan A.; Kraemer, David J. M.; Dunbar, Kevin N.

    2008-01-01

    Here, we investigate how activation of mental representations of categories during analogical reasoning influences subsequent cognitive processing. Specifically, we present and test the central predictions of the "Micro-Category" account of analogy. This account emphasizes the role of categories in aligning terms for analogical mapping. In a…

  13. State-of-the-art Sn2+-based ternary oxides as photocatalysts for water splitting: electronic structures and optoelectronic properties

    KAUST Repository

    Noureldine, Dalal

    2016-09-19

    Developing visible light responsive metal oxide photocatalysts is a challenge that must be conquered to achieve high efficiency for water splitting or hydrogen evolution reactions. Valence band engineering is possible by forming ternary oxides using the combination of a metal cation with an s2d10 electronic configuration and a transition metal oxide with a d0 configuration. Many (Sn2+, Bi3+, Pb2+)-based ternary metal oxide photocatalysts have been reported for hydrogen and/or oxygen evolution under visible irradiation. Sn2+-based materials have attracted particular attention because tin is inexpensive, abundant and more environmentally friendly than lead or bismuth. In this review, we provide a fruitful library for Sn2+-based photocatalysts that have been reported to evolve hydrogen using sacrificial reagents, including SnNb2O6, Sn2Nb2O7, SnTaxNb2−xO6, SnTa2O6, Sn2Ta2O7, SnWO4 (α and β phases), SnSb2O6·nH2O, and Sn2TiO4. The synthesis method used in the literature and the resultant morphology and crystal structure of each compound are discussed. The density functional theory (DFT) calculations of the electronic structure and density of states are provided, and the consequent optoelectronic properties such as band gap, nature of the bandgap, dielectric constant, and effective masses are summarized. This review will help highlight the main challenges for Sn2+-based materials.

  14. State-of-the-art Sn2+-based ternary oxides as photocatalysts for water splitting: electronic structures and optoelectronic properties

    KAUST Repository

    Noureldine, Dalal; Takanabe, Kazuhiro

    2016-01-01

    Developing visible light responsive metal oxide photocatalysts is a challenge that must be conquered to achieve high efficiency for water splitting or hydrogen evolution reactions. Valence band engineering is possible by forming ternary oxides using the combination of a metal cation with an s2d10 electronic configuration and a transition metal oxide with a d0 configuration. Many (Sn2+, Bi3+, Pb2+)-based ternary metal oxide photocatalysts have been reported for hydrogen and/or oxygen evolution under visible irradiation. Sn2+-based materials have attracted particular attention because tin is inexpensive, abundant and more environmentally friendly than lead or bismuth. In this review, we provide a fruitful library for Sn2+-based photocatalysts that have been reported to evolve hydrogen using sacrificial reagents, including SnNb2O6, Sn2Nb2O7, SnTaxNb2−xO6, SnTa2O6, Sn2Ta2O7, SnWO4 (α and β phases), SnSb2O6·nH2O, and Sn2TiO4. The synthesis method used in the literature and the resultant morphology and crystal structure of each compound are discussed. The density functional theory (DFT) calculations of the electronic structure and density of states are provided, and the consequent optoelectronic properties such as band gap, nature of the bandgap, dielectric constant, and effective masses are summarized. This review will help highlight the main challenges for Sn2+-based materials.

  15. Correlation of Mn charge state with the electrical resistivity of Mn doped indium tin oxide thin films

    KAUST Repository

    Kumar, S. R. Sarath; Hedhili, Mohamed N.; Alshareef, Husam N.; Kasiviswanathan, S.

    2010-01-01

    Correlation of charge state of Mn with the increase in resistivity with Mn concentration is demonstrated in Mn-doped indium tin oxide films. Bonding analysis shows that Mn 2p3/2 core level can be deconvoluted into three components corresponding to Mn2+ and Mn4+ with binding energies 640.8 eV and 642.7 eV, respectively, and a Mn2+ satellite at ∼5.4 eV away from the Mn2+ peak. The presence of the satellite peak unambiguously proves that Mn exists in the +2 charge state. The ratio of concentration of Mn2+ to Mn4+ of ∼4:1 suggests that charge compensation occurs in the n-type films causing the resistivity increase.

  16. Correlation of Mn charge state with the electrical resistivity of Mn doped indium tin oxide thin films

    KAUST Repository

    Kumar, S. R. Sarath

    2010-09-15

    Correlation of charge state of Mn with the increase in resistivity with Mn concentration is demonstrated in Mn-doped indium tin oxide films. Bonding analysis shows that Mn 2p3/2 core level can be deconvoluted into three components corresponding to Mn2+ and Mn4+ with binding energies 640.8 eV and 642.7 eV, respectively, and a Mn2+ satellite at ∼5.4 eV away from the Mn2+ peak. The presence of the satellite peak unambiguously proves that Mn exists in the +2 charge state. The ratio of concentration of Mn2+ to Mn4+ of ∼4:1 suggests that charge compensation occurs in the n-type films causing the resistivity increase.

  17. Chemical state analysis of oxide thin films using a high resolution double crystal X-ray fluorescence spectrometer

    International Nuclear Information System (INIS)

    Masuda, Hirohisa; Morinaga, Kenji; Ohta, Yoshio.

    1995-01-01

    The chemical state analysis of r.f.-sputtered amorphous oxide thin films was determined by a high resolution X-ray fluorescence spectrometer with double crystals. The polymerization degree of silicate anions in the silicate film was as same as a target (α-Quartz). The oxygen coordination number of Al 3+ ions in the aluminate film was different from a target (α-Al 2 O 3 ), and it was a mixture of 4 and 6 in a spinel-like structure. In CaO-SiO 2 and CaO-Al 2 O 3 films, when the film thickness is thin at the beginning of sputtering, the composition of films are in the shortage of CaO. But when the film thickness become thicker, the composition of films become as same as the target. From the results above, the chemical state of films and their variations with film thickness can be clarified by using the apparatus. (author)

  18. Study of the oxidation state of arsenic and uranium in individual particles from uranium mine tailings, Hungary

    International Nuclear Information System (INIS)

    Alsecz, A.; Osan, J.; Palfalvi, J.; Torok, Sz.; Sajo, I.; Mathe, Z.; Simon, R.; Falkenberg, G.

    2007-01-01

    Uranium ore mining and milling have been terminated in the Mecsek Mountains (southwest Hungary) in 1997. Mine tailings ponds are located between two important water bases, which are resources of the drinking water of the city of Pecs and the neighbouring villages. The average U concentration of the tailings material is 71.73 μg/g, but it is inhomogeneous. Some microscopic particles contain orders of magnitude more U than the rest of the tailings material. Other potentially toxic elements are As and Pb of which chemical state is important to estimate mobility, because in mobile form they can risk the water basis and the public health. Individual U-rich particles were selected with solid state nuclear track detector (SSNTD) and after localisation the particles were investigated by synchrotron radiation based microanalytical techniques. The distribution of elements over the particles was studied by micro beam X-ray fluorescence (μ-XRF) and the oxidation state of uranium and arsenic was determined by micro X-ray absorption near edge structure (μ-XANES) spectroscopy. Some of the measured U-rich particles were chosen for studying the heterogeneity with μ-XRF tomography. Arsenic was present mainly in As(V) and uranium in U(VI) form in the original uranium ore particles, but in the mine tailings samples uranium was present mainly in the less mobile U(IV) form. Correlation was found between the oxidation state of As and U in the same analyzed particles. These results suggest that dissolution of uranium is not expected in short term period. (authors)

  19. An unusual high-spin ground state of Co3+ in octahedral coordination in brownmillerite-type cobalt oxide.

    Science.gov (United States)

    Istomin, S Ya; Tyablikov, O A; Kazakov, S M; Antipov, E V; Kurbakov, A I; Tsirlin, A A; Hollmann, N; Chin, Y Y; Lin, H-J; Chen, C T; Tanaka, A; Tjeng, L H; Hu, Z

    2015-06-21

    The crystal and magnetic structures of brownmillerite-like Sr(2)Co(1.2)Ga(0.8)O(5) with a stable Co(3+) oxidation state at both octahedral and tetrahedral sites are refined using neutron powder diffraction data collected at 2 K (S.G. Icmm, a = 5.6148(6) Å, b = 15.702(2) Å, c = 5.4543(6) Å; R(wp) = 0.0339, R(p) = 0.0443, χ(2) = 0.775). The very large tetragonal distortion of CoO(6) octahedra (1.9591(4) Å for Co-O(eq) and 2.257(6) Å for Co-O(ax)) could be beneficial for the stabilization of the long-sought intermediate-spin state of Co(3+) in perovskite-type oxides. However, the large magnetic moment of octahedral Co(3+) (3.82(7)μ(B)) indicates the conventional high-spin state of Co(3+) ions, which is further supported by the results of a combined theoretical and experimental soft X-ray absorption spectroscopy study at the Co-L(2,3) edges on Sr(2)Co(1.2)Ga(0.8)O(5). A high-spin ground state of Co(3+) in Sr(2)Co(1.2)Ga(0.8)O(5) resulted in much lower in comparison with a LaCoO(3) linear thermal expansion coefficient of 13.1 ppm K(-1) (298-1073 K) determined from high-temperature X-ray powder diffraction data collected in air.

  20. Electronic States of High-k Oxides in Gate Stack Structures

    Science.gov (United States)

    Zhu, Chiyu

    In this dissertation, in-situ X-ray and ultraviolet photoemission spectroscopy have been employed to study the interface chemistry and electronic structure of potential high-k gate stack materials. In these gate stack materials, HfO2 and La2O3 are selected as high-k dielectrics, VO2 and ZnO serve as potential channel layer materials. The gate stack structures have been prepared using a reactive electron beam system and a plasma enhanced atomic layer deposition system. Three interrelated issues represent the central themes of the research: 1) the interface band alignment, 2) candidate high-k materials, and 3) band bending, internal electric fields, and charge transfer. 1) The most highlighted issue is the band alignment of specific high-k structures. Band alignment relationships were deduced by analysis of XPS and UPS spectra for three different structures: a) HfO2/VO2/SiO2/Si, b) HfO 2-La2O3/ZnO/SiO2/Si, and c) HfO 2/VO2/ HfO2/SiO2/Si. The valence band offset of HfO2/VO2, ZnO/SiO2 and HfO 2/SiO2 are determined to be 3.4 +/- 0.1, 1.5 +/- 0.1, and 0.7 +/- 0.1 eV. The valence band offset between HfO2-La2O3 and ZnO was almost negligible. Two band alignment models, the electron affinity model and the charge neutrality level model, are discussed. The results show the charge neutrality model is preferred to describe these structures. 2) High-k candidate materials were studied through comparison of pure Hf oxide, pure La oxide, and alloyed Hf-La oxide films. An issue with the application of pure HfO2 is crystallization which may increase the leakage current in gate stack structures. An issue with the application of pure La2O3 is the presence of carbon contamination in the film. Our study shows that the alloyed Hf-La oxide films exhibit an amorphous structure along with reduced carbon contamination. 3) Band bending and internal electric fields in the gate stack structure were observed by XPS and UPS and indicate the charge transfer during the growth and process. The oxygen

  1. Influence of oxidation state on the absorption of plutonium from the gastrointestinal tract

    International Nuclear Information System (INIS)

    Sullivan, M.F.; Ryan, J.L.; Gorham, L.S.; McFadden, K.M.

    1979-01-01

    Rats and guinea pigs treated intragastrically with either IV- or VI-valent 238 Pu showed no appreciable difference in absorption. Nitric acid solutions of 239 Pu (pH 2) were also administered to fasted and fed rats. When an oxidant (K 2 Cr 2 O 7 ) was present in the solution gavaged to fasted rats, absorption increased 34-fold. However, when 239 Pu VI was administered to fed rats in the absence of dichromate, there was no appreciable difference between the absorption of 239 Pu VI and 239 Pu IV

  2. Micro-XANES measurements on experimental spinels and the oxidation state of vanadium in coexisting spinel and silicate melt

    International Nuclear Information System (INIS)

    Righter, K.; Sutton, S.R.; Newville, M.; Le, L.; Schwandt, C.S.

    2006-01-01

    We show that experimental spinels coexisting with silicate melt always have lower valence vanadium, and that spinels typically have 3+, whereas the coexisting melt has 4+ or 5+. Implications of these results for planetary basalts will be discussed. Spinel can be a significant host phase for V which has multiple oxidation states V 2+ , V 3+ , V 4+ or V 5+ at oxygen fugacities relevant to natural systems. The magnitude of D(V) spinel/melt is known to be a function of composition, temperature and fO 2 , but the uncertainty of the oxidation state under the range of natural conditions has made elusive a thorough understanding of D(V) spinel/melt. For example, V 3+ is likely to be stable in spinels, based on exchange with Al in experiments in the CaO-MgO-Al 2 O 3 -SiO 2 system. On the other hand, it has been argued that V 4+ will be stable across the range of natural oxygen fugacities in nature. In order to build on our previous work in more oxidized systems, we have carried out experiments at relatively reducing conditions from the FMQ buffer to 2 log fO 2 units below the IW buffer. These spinel-melt pairs, where V is present in the spinel at natural levels (∼300 ppm V), were analyzed using an electron microprobe at NASA-JSC and mi-cro-XANES at the Advanced Photon Source at Argonne National Laboratory. The new results will be used together with previous results to understand the valence of V in spinel-melt systems across 12 orders of magnitude of oxygen fugacity, and with application to natural systems.

  3. Solid-state voltammetry-based electrochemical immunosensor for Escherichia coli using graphene oxide-Ag nanoparticle composites as labels.

    Science.gov (United States)

    Jiang, Xiaochun; Chen, Kun; Wang, Jing; Shao, Kang; Fu, Tao; Shao, Feng; Lu, Donglian; Liang, Jiangong; Foda, M Frahat; Han, Heyou

    2013-06-21

    A new electrochemical immunosensor based on solid-state voltammetry was fabricated for the detection of Escherichia coli (E. coli) by using graphene oxide-Ag nanoparticle composites (P-GO-Ag) as labels. To construct the platform, Au nanoparticles (AuNPs) were first self-assembled on an Au electrode surface through cysteamine and served as an effective matrix for antibody (Ab) attachment. Under a sandwich-type immunoassay format, the analyte and the probe (P-GO-Ag-Ab) were successively captured onto the immunosensor. Finally, the bonded AgNPs were detected through a solid-state redox process in 0.2 M of KCl solution. Combining the advantages of the high-loading capability of graphene oxide with promoted electron-transfer rate of AuNPs, this immunosensor produced a 26.92-fold signal enhancement compared with the unamplified protocol. Under the optimal conditions, the immunosensor exhibited a wide linear dependence on the logarithm of the concentration of E. coli ranging from 50 to 1.0 × 10(6) cfu mL(-1) with a detection limit of 10 cfu mL(-1). Moreover, as a practical application, the proposed immunosensor was used to monitor E. coli in lake water with satisfactory results.

  4. Chromium Oxidation State in Planetary Basalts: Oxygen Fugacity Indicator and Critical Variable for Cr-Spinel Stability

    Science.gov (United States)

    Bell, A. S.; Burger, P. V.; Le, Loan; Papike, J. J.; Jone, J.; Shearer, C. K.

    2014-01-01

    Cr is a ubiquitous and relatively abundant minor element in basaltic, planetary magmas. At the reduced oxidation states (oxidation state of Cr in in silicate melts. Here we present a series of 1-bar gas mixing experiments performed with a Fe-rich basaltic melt in which have determined the Cr redox ratio of the melt at over a range of fO2 values by measuring this quantity in olivine with X-ray Absorption Near Edge Spectroscopy (XANES). The measured Cr redox ratio of the olivine phenocrysts can be readily converted to the ratio present in the conjugate melt via the ratio of crystal-liquid partition coefficients for Cr3+ and Cr2+. We have applied these results to modeling Cr spinel stability and Cr redox ratios in a primitive, iron-rich martian basalt.

  5. Oxidation of tertiary amines by cytochrome p450-kinetic isotope effect as a spin-state reactivity probe.

    Science.gov (United States)

    Li, Chunsen; Wu, Wei; Cho, Kyung-Bin; Shaik, Sason

    2009-08-24

    Two types of tertiary amine oxidation processes, namely, N-dealkylation and N-oxygenation, by compound I (Cpd I) of cytochrome P450 are studied theoretically using hybrid DFT calculations. All the calculations show that both N-dealkylation and N-oxygenation of trimethylamine (TMA) proceed preferentially from the low-spin (LS) state of Cpd I. Indeed, the computed kinetic isotope effects (KIEs) for the rate-controlling hydrogen abstraction step of dealkylation show that only the KIE(LS) fits the experimental datum, whereas the corresponding value for the high-spin (HS) process is much higher. These results second those published before for N,N-dimethylaniline (DMA), and as such, they further confirm the conclusion drawn then that KIEs can be a sensitive probe of spin state reactivity. The ferric-carbinolamine of TMA decomposes most likely in a non-enzymatic reaction since the Fe-O bond dissociation energy (BDE) is negative. The computational results reveal that in the reverse reaction of N-oxygenation, the N-oxide of aromatic amine can serve as a better oxygen donor than that of aliphatic amine to generate Cpd I. This capability of the N-oxo derivatives of aromatic amines to transfer oxygen to the heme, and thereby generate Cpd I, is in good accord with experimental data previously reported.

  6. Identification of the iron oxidation state and coordination geometry in iron oxide- and zeolite-based catalysts using pre-edge XAS analysis.

    Science.gov (United States)

    Boubnov, Alexey; Lichtenberg, Henning; Mangold, Stefan; Grunwaldt, Jan Dierk

    2015-03-01

    Analysis of the oxidation state and coordination geometry using pre-edge analysis is attractive for heterogeneous catalysis and materials science, especially for in situ and time-resolved studies or highly diluted systems. In the present study, focus is laid on iron-based catalysts. First a systematic investigation of the pre-edge region of the Fe K-edge using staurolite, FePO4, FeO and α-Fe2O3 as reference compounds for tetrahedral Fe(2+), tetrahedral Fe(3+), octahedral Fe(2+) and octahedral Fe(3+), respectively, is reported. In particular, high-resolution and conventional X-ray absorption spectra are compared, considering that in heterogeneous catalysis and material science a compromise between high-quality spectroscopic data acquisition and simultaneous analysis of functional properties is required. Results, which were obtained from reference spectra acquired with different resolution and quality, demonstrate that this analysis is also applicable to conventionally recorded pre-edge data. For this purpose, subtraction of the edge onset is preferentially carried out using an arctangent and a first-degree polynomial, independent of the resolution and quality of the data. For both standard and high-resolution data, multiplet analysis of pre-edge features has limitations due to weak transitions that cannot be identified. On the other hand, an arbitrary empirical peak fitting assists the analysis in that non-local transitions can be isolated. The analysis of the oxidation state and coordination geometry of the Fe sites using a variogram-based method is shown to be effective for standard-resolution data and leads to the same results as for high-resolution spectra. This method, validated by analysing spectra of reference compounds and their well defined mixtures, is finally applied to track structural changes in a 1% Fe/Al2O3 and a 0.5% Fe/BEA zeolite catalyst during reduction in 5% H2/He. The results, hardly accessible by other techniques, show that Fe(3+) is

  7. Identification of different oxygen species in oxide nanostructures with 17O solid-state NMR spectroscopy

    Science.gov (United States)

    Wang, Meng; Wu, Xin-Ping; Zheng, Sujuan; Zhao, Li; Li, Lei; Shen, Li; Gao, Yuxian; Xue, Nianhua; Guo, Xuefeng; Huang, Weixin; Gan, Zhehong; Blanc, Frédéric; Yu, Zhiwu; Ke, Xiaokang; Ding, Weiping; Gong, Xue-Qing; Grey, Clare P.; Peng, Luming

    2015-01-01

    Nanostructured oxides find multiple uses in a diverse range of applications including catalysis, energy storage, and environmental management, their higher surface areas, and, in some cases, electronic properties resulting in different physical properties from their bulk counterparts. Developing structure-property relations for these materials requires a determination of surface and subsurface structure. Although microscopy plays a critical role owing to the fact that the volumes sampled by such techniques may not be representative of the whole sample, complementary characterization methods are urgently required. We develop a simple nuclear magnetic resonance (NMR) strategy to detect the first few layers of a nanomaterial, demonstrating the approach with technologically relevant ceria nanoparticles. We show that the 17O resonances arising from the first to third surface layer oxygen ions, hydroxyl sites, and oxygen species near vacancies can be distinguished from the oxygen ions in the bulk, with higher-frequency 17O chemical shifts being observed for the lower coordinated surface sites. H217O can be used to selectively enrich surface sites, allowing only these particular active sites to be monitored in a chemical process. 17O NMR spectra of thermally treated nanosized ceria clearly show how different oxygen species interconvert at elevated temperature. Density functional theory calculations confirm the assignments and reveal a strong dependence of chemical shift on the nature of the surface. These results open up new strategies for characterizing nanostructured oxides and their applications. PMID:26601133

  8. Influence of de-hulled rapeseed roasting on the physicochemical composition and oxidative state of oil

    International Nuclear Information System (INIS)

    Rękas, A.; Siger, A.; Wroniak, M.; Ścibisz, I.; Derewiaka, D.; Anders, A.

    2017-01-01

    The effect of roasting time on the contents of bioactive compounds (tocopherols, phytosterols, phenolic compounds), antioxidant capacity and physicochemical properties of rapeseed oil pressed from de-hulled seeds was investigated. The de-hulled seeds were roasted at a temperature of 165 °C for 20, 40, 60, 80, and 100 min. The results of this study show that a roasting pre-treatment led to a gradual increase in canolol content (from 1.34 to 117.33 mg/100 g), total phytosterols (from 573.51 to 609.86 mg/100 g) and total carotenoids (0.82 to 2.41 mg/100 g), while only slight changes in the contents of tocopherols were noted. With the increase in roasting time a gradual increase in oxidative stability (from 4.27 to 6.85 h), and antioxidant capacity, seen mainly in the hydrophilic fraction of oil (from 0.32 to 2.30 mmol TEAC/l) was found. Although roasting resulted in the formation of primary and secondary oxidation products, the quality parameters of oils were within Codex Alimentarius limits. [es

  9. Fluid analog model for boundary effects in field theory

    International Nuclear Information System (INIS)

    Ford, L. H.; Svaiter, N. F.

    2009-01-01

    Quantum fluctuations in the density of a fluid with a linear phonon dispersion relation are studied. In particular, we treat the changes in these fluctuations due to nonclassical states of phonons and to the presence of boundaries. These effects are analogous to similar effects in relativistic quantum field theory, and we argue that the case of the fluid is a useful analog model for effects in field theory. We further argue that the changes in the mean squared density are, in principle, observable by light scattering experiments.

  10. Are all analogies created equal? Prefrontal cortical functioning may predict types of analogical reasoning.

    Science.gov (United States)

    Chrysikou, Evangelia G; Thompson-Schill, Sharon L

    2010-06-01

    Abstract The proposed theory can account for analogies based on learned relationships between elements in the source and target domains. However, its explanatory power regarding the discovery of new relationships during analogical reasoning is limited. We offer an alternative perspective for the role of PFC in analogical thought that may better address different types of analogical mappings.

  11. Elevated oxidative stress monitored via the albumin-thiol redox state is correlated with matrix metalloproteinase-3 elevation in patients with rheumatoid arthritis.

    Science.gov (United States)

    Kizaki, Kazuha; Yoshizumi, Yusuke; Takahashi, Teppei; Era, Seiichi

    2015-01-01

    In rheumatoid arthritis (RA), matrix metalloproteinase-3 (MMP-3) and oxidative stress contribute to joint destruction. However, little is known about the relationship between MMP-3 and oxidative stress in RA. We measured the albumin-thiol redox state as a marker of oxidative stress, MMP-3, and the DAS-28 score calculated using CRP values among forty-seven patients (9 males and 38 females) with RA. According to the serum MMP-3 levels, they were divided into two groups (group A: within normal ranges of 36.9-121.0 ng/mL for men and 17.3-59.7 ng/mL for women; group B: above normal ranges). The albumin-thiol redox state in group B was significantly oxidized compared with that in group A (p < 0.01). The percentage of oxidized albumin-thiol showed a positive correlation with serum MMP-3 (r = 0.52). DAS-28 and CRP were also correlated with the percentage of oxidized albumin-thiol (r = 0.46, r = 0.44). The albumin-thiol redox state was significantly oxidized in correlation with serum MMP-3 elevation in RA.

  12. Practical analog electronics for technicians

    CERN Document Server

    Kimber, W A

    2013-01-01

    'Practical Analog Electronics for Technicians' not only provides an accessible introduction to electronics, but also supplies all the problems and practical activities needed to gain hands-on knowledge and experience. This emphasis on practice is surprisingly unusual in electronics texts, and has already gained Will Kimber popularity through the companion volume, 'Practical Digital Electronics for Technicians'. Written to cover the Advanced GNVQ optional unit in electronics, this book is also ideal for BTEC National, A-level electronics and City & Guilds courses. Together with 'Practical Digit

  13. Analog and mixed-signal electronics

    CERN Document Server

    Stephan, Karl

    2015-01-01

    A practical guide to analog and mixed-signal electronics, with an emphasis on design problems and applications This book provides an in-depth coverage of essential analog and mixed-signal topics such as power amplifiers, active filters, noise and dynamic range, analog-to-digital and digital-to-analog conversion techniques, phase-locked loops, and switching power supplies. Readers will learn the basics of linear systems, types of nonlinearities and their effects, op-amp circuits, the high-gain analog filter-amplifier, and signal generation. The author uses system design examples to motivate

  14. Analog circuit design art, science, and personalities

    CERN Document Server

    Williams, Jim

    1991-01-01

    Analog Circuit Design: Art, Science, and Personalities discusses the many approaches and styles in the practice of analog circuit design. The book is written in an informal yet informative manner, making it easily understandable to those new in the field. The selection covers the definition, history, current practice, and future direction of analog design; the practice proper; and the styles in analog circuit design. The book also includes the problems usually encountered in analog circuit design; approach to feedback loop design; and other different techniques and applications. The text is

  15. Spiral spin state in high-temperature copper-oxide superconductors: Evidence from neutron scattering measurements

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    2005-01-01

    An effective spiral spin phase ground state provides a new paradigm for the high-temperature superconducting cuprates. It accounts for the recent neutron scattering observations of spin excitations regarding both the energy dispersion and the intensities, including the "universal" rotation by 45...... model. The form of the exchange interaction function reveals the effects of the Fermi surface, and the unique shape predicts large quantum spin fluctuations in the ground state....

  16. Correlation of the oxidation state of cerium in sol-gel glasses as a function of thermal treatment via optical spectroscopy and XANES studies.

    Science.gov (United States)

    Assefa, Zerihun; Haire, R G; Caulder, D L; Shuh, D K

    2004-07-01

    Sol-gel glass matrices containing lanthanides have numerous technological applications and their formation involves several chemical facets. In the case of cerium, its ability to exist in two different oxidation states or in mixed valence state provides additional complexities for the sol-gel process. The oxidation state of cerium present during different facets of preparation of sol-gel glasses, and also as a function of the starting oxidation state of cerium added, were studied both by optical spectroscopy and X-ray absorption near-edge structures (XANES). The findings acquired by each approach were compared. The primary focus was on the redox chemistries associated with sample preparation, gelation, and thermal treatment. When Ce3+ is introduced into the starting sols, the trivalent state normally prevails in the wet and room temperature-dried gels. Heating in air at >100 degrees C can generate a light yellow coloration with partial oxidation to the tetravalent state. Above 200 degrees C and up to approximately 1000 degrees C, cerium is oxidized to its tetravalent state. In contrast, when tetravalent cerium is introduced into the sol, both the wet and room temperature-dried gels lose the yellow-brown color of the initial ceric ammonium nitrate solution. When the sol-gel is heated to 110 degrees C it turns yellowish as the cerium tends to be re-oxidized. The yellow color is believed to represent the effect of oxidation and oligomerization of the cerium-silanol units in the matrix. The luminescence properties are also affected by these changes, the details of which are reported herein.

  17. Nilpotent Quantum Mechanics: Analogs and Applications

    Directory of Open Access Journals (Sweden)

    Peter Marcer

    2017-07-01

    Full Text Available The most significant characteristic of nilpotent quantum mechanics is that the quantum system (fermion state and its environment (vacuum are, in mathematical terms, mirror images of each other. So a change in one automatically leads to corresponding changes in the other. We have used this characteristic as a model for self-organization, which has applications well beyond quantum physics. The nilpotent structure has also been identified as being constructed from two commutative vector spaces. This zero square-root construction has a number of identifiable characteristics which we can expect to find in systems where self-organization is dominant, and a case presented after the publication of a paper by us on “The ‘Logic’ of Self-Organizing Systems” [1], in the organization of the neurons in the visual cortex. We expect to find many more complex systems where our general principles, based, by analogy, on nilpotent quantum mechanics, will apply.

  18. In-situ preparation of poly(ethylene oxide)/Li3PS4 hybrid polymer electrolyte with good nanofiller distribution for rechargeable solid-state lithium batteries

    Science.gov (United States)

    Chen, Shaojie; Wang, Junye; Zhang, Zhihua; Wu, Linbin; Yao, Lili; Wei, Zhenyao; Deng, Yonghong; Xie, Dongjiu; Yao, Xiayin; Xu, Xiaoxiong

    2018-05-01

    Nano-sized fillers in a polymer matrix with good distribution can play a positive role in improving polymer electrolytes in the aspects of ionic conductivity, mechanical property and electrochemical performance of Li-ion cells. Herein, polyethylene oxide (PEO)/Li3PS4 hybrid polymer electrolyte is prepared via a new in-situ approach. The ionic conductivities of the novel hybrid electrolytes with variable proportions are measured, and the optimal electrolyte of PEO-2%vol Li3PS4 presents a considerable ionic conductivity of 8.01 × 10-4 S cm-1 at 60 °C and an electrochemical window up to 5.1 V. The tests of DSC and EDXS reveal that the Li3PS4 nanoparticles with better distribution, as active fillers scattering in the PEO, exhibit a positive effect on the transference of lithium ion and electrochemical interfacial stabilities. Finally, the assembled solid-state LiFePO4/Li battery presents a decent cycling performance (80.9% retention rate after 325 cycles at 60 °C) and excellent rate capacities with 153, 143, 139 and 127 mAh g-1 at the discharging rate of 0.1 C, 0.2 C, 0.5 C and 1 C at 60 °C. It is fully proved that it is an advanced strategy to preparing the new organic/inorganic hybrid electrolytes for lithium-ion batteries applications.

  19. Electrochemical determination of the oxidation potentials and the thermodynamic stability of the valence states of the transuranium elements in aqueous alkaline media

    International Nuclear Information System (INIS)

    Peretrukhin, V.F.; Spitsyn, V.I.

    1982-01-01

    The oxidation potentials of neptunium, plutonium, and americium in the valance states from (III) to (VII) have been determined experimentally in 0.1-15 M NaOH. Heptavalent plutonium and americium are thermodynamically able to oxidize water with the evolution of oxygen in 0.1-15 M NaOH, neptunium(VII) in 0.1-7 M NaOH. All valance states of plutonium resist disproportionation in alkaline solutions; in the case of neptunium and americium only one disproportionation reaction is possible; of the hexavalent state in to penta- and heptavalent states. The degree of completion of the reaction can be calculated accurately from the oxidation potentials determined

  20. CMOS analog integrated circuit design technology; CMOS anarogu IC sekkei gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, H.; Fujisawa, A. [Fuji Electric Co. Ltd., Tokyo (Japan)

    2000-08-10

    In the field of the LSI (large scale integrated circuit) in rapid progress toward high integration and advanced functions, CAD (computer-aided design) technology has become indispensable to LSI development within a short period. Fuji Electric has developed design technologies and automatic design system to develop high-quality analog ICs (integrated circuits), including power supply ICs. within a short period. This paper describes CMOS (complementary metal-oxide semiconductor) analog macro cell, circuit simulation, automatic routing, and backannotation technologies. (author)

  1. Autophagy and oxidative stress in non-communicable diseases: A matter of the inflammatory state?

    Science.gov (United States)

    Peña-Oyarzun, Daniel; Bravo-Sagua, Roberto; Diaz-Vega, Alexis; Aleman, Larissa; Chiong, Mario; Garcia, Lorena; Bambs, Claudia; Troncoso, Rodrigo; Cifuentes, Mariana; Morselli, Eugenia; Ferreccio, Catterina; Quest, Andrew F G; Criollo, Alfredo; Lavandero, Sergio

    2018-05-30

    Non-communicable diseases (NCDs), also known as chronic diseases, are long-lasting conditions that affect millions of people around the world. Different factors contribute to their genesis and progression; however they share common features, which are critical for the development of novel therapeutic strategies. A persistently altered inflammatory response is typically observed in many NCDs together with redox imbalance. Additionally, dysregulated proteostasis, mainly derived as a consequence of compromised autophagy, is a common feature of several chronic diseases. In this review, we discuss the crosstalk among inflammation, autophagy and oxidative stress, and how they participate in the progression of chronic diseases such as cancer, cardiovascular diseases, obesity and type II diabetes mellitus. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. Brain oxidative metabolism of the newborn dog: correlation between 31P NMR spectroscopy and pyridine nucleotide redox state.

    Science.gov (United States)

    Mayevsky, A; Nioka, S; Subramanian, V H; Chance, B

    1988-04-01

    The effects of both anoxia and short- and long-term hypoxia on brain oxidative metabolism were studied in newborn dogs. Oxidative metabolism was evaluated by two independent measures: in vivo continuous monitoring of mitochondrial NADH redox state and energy stores as calculated from the phosphocreatine (PCr)/Pi levels measured by 31P nuclear magnetic resonance (NMR) spectroscopy. The hemodynamic response to low oxygen supply was further evaluated by measuring the changes in the reflected light intensity at 366 nm (the excitation wavelength for NADH). The animal underwent surgery and was prepared for monitoring of the two signals (NADH and PCr/Pi). It was then placed inside a Phosphoenergetics 260-80 NMR spectrometer magnet with a 31-cm bore. Each animal (1-21 days old) was exposed to short-term anoxia or hypoxia as well as to long-term hypoxia (1-2 h). The results can be summarized as follow: (a) In the normoxic brain, the ratio between PCr and Pi was greater than 1 (1.2-1.4), while under hypoxia or asphyxia a significant decrease that was correlated to the FiO2 levels was recorded. (b) A clear correlation was found between the decrease in PCr/Pi values and the increased NADH redox state developed under decreased O2 supply to the brain. (c) Exposing the animal to moderately long-term hypoxia led to a stabilized low-energy state of the brain with a good recovery after rebreathing normal air. (d) Under long-term and severe hypoxia, the microcirculatory autoregulatory mechanism was damaged and massive vasoconstriction was optically recorded simultaneously with a significant decrease in PCr/Pi values.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Visual analog rating of mood by people with aphasia.

    Science.gov (United States)

    Haley, Katarina L; Womack, Jennifer L; Harmon, Tyson G; Williams, Sharon W

    2015-08-01

    Considerable attention has been given to the identification of depression in stroke survivors with aphasia, but there is more limited information about other mood states. Visual analog scales are often used to collect subjective information from people with aphasia. However, the validity of these methods for communicating about mood has not been established in people with moderately to severely impaired language. The dual purposes of this study were to characterize the relative endorsement of negative and positive mood states in people with chronic aphasia after stroke and to examine congruent validity for visual analog rating methods for people with a range of aphasia severity. Twenty-three left-hemisphere stroke survivors with aphasia were asked to indicate their present mood by using two published visual analog rating methods. The congruence between the methods was estimated through correlation analysis, and scores for different moods were compared. Endorsement was significantly stronger for "happy" than for mood states with negative valence. At the same time, several participants displayed pronounced negative mood compared to previously published norms for neurologically healthy adults. Results from the two rating methods were moderately and positively correlated. Positive mood is prominent in people with aphasia who are in the chronic stage of recovery after stroke, but negative moods can also be salient and individual presentations are diverse. Visual analog rating methods are valid methods for discussing mood with people with aphasia; however, design optimization should be explored.

  4. Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

    Science.gov (United States)

    Li, Jingyi; Mao, Jingqiu; Fiore, Arlene M.; Cohen, Ronald C.; Crounse, John D.; Teng, Alex P.; Wennberg, Paul O.; Lee, Ben H.; Lopez-Hilfiker, Felipe D.; Thornton, Joel A.; Peischl, Jeff; Pollack, Ilana B.; Ryerson, Thomas B.; Veres, Patrick; Roberts, James M.; Neuman, J. Andrew; Nowak, John B.; Wolfe, Glenn M.; Hanisco, Thomas F.; Fried, Alan; Singh, Hanwant B.; Dibb, Jack; Paulot, Fabien; Horowitz, Larry W.

    2018-02-01

    Widespread efforts to abate ozone (O3) smog have significantly reduced emissions of nitrogen oxides (NOx) over the past 2 decades in the Southeast US, a place heavily influenced by both anthropogenic and biogenic emissions. How reactive nitrogen speciation responds to the reduction in NOx emissions in this region remains to be elucidated. Here we exploit aircraft measurements from ICARTT (July-August 2004), SENEX (June-July 2013), and SEAC4RS (August-September 2013) and long-term ground measurement networks alongside a global chemistry-climate model to examine decadal changes in summertime reactive oxidized nitrogen (RON) and ozone over the Southeast US. We show that our model can reproduce the mean vertical profiles of major RON species and the total (NOy) in both 2004 and 2013. Among the major RON species, nitric acid (HNO3) is dominant (˜ 42-45 %), followed by NOx (31 %), total peroxy nitrates (ΣPNs; 14 %), and total alkyl nitrates (ΣANs; 9-12 %) on a regional scale. We find that most RON species, including NOx, ΣPNs, and HNO3, decline proportionally with decreasing NOx emissions in this region, leading to a similar decline in NOy. This linear response might be in part due to the nearly constant summertime supply of biogenic VOC emissions in this region. Our model captures the observed relative change in RON and surface ozone from 2004 to 2013. Model sensitivity tests indicate that further reductions of NOx emissions will lead to a continued decline in surface ozone and less frequent high-ozone events.

  5. Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

    Directory of Open Access Journals (Sweden)

    J. Li

    2018-02-01

    Full Text Available Widespread efforts to abate ozone (O3 smog have significantly reduced emissions of nitrogen oxides (NOx over the past 2 decades in the Southeast US, a place heavily influenced by both anthropogenic and biogenic emissions. How reactive nitrogen speciation responds to the reduction in NOx emissions in this region remains to be elucidated. Here we exploit aircraft measurements from ICARTT (July–August 2004, SENEX (June–July 2013, and SEAC4RS (August–September 2013 and long-term ground measurement networks alongside a global chemistry–climate model to examine decadal changes in summertime reactive oxidized nitrogen (RON and ozone over the Southeast US. We show that our model can reproduce the mean vertical profiles of major RON species and the total (NOy in both 2004 and 2013. Among the major RON species, nitric acid (HNO3 is dominant (∼ 42–45 %, followed by NOx (31 %, total peroxy nitrates (ΣPNs; 14 %, and total alkyl nitrates (ΣANs; 9–12 % on a regional scale. We find that most RON species, including NOx, ΣPNs, and HNO3, decline proportionally with decreasing NOx emissions in this region, leading to a similar decline in NOy. This linear response might be in part due to the nearly constant summertime supply of biogenic VOC emissions in this region. Our model captures the observed relative change in RON and surface ozone from 2004 to 2013. Model sensitivity tests indicate that further reductions of NOx emissions will lead to a continued decline in surface ozone and less frequent high-ozone events.

  6. Analogy in causal inference: rethinking Austin Bradford Hill's neglected consideration.

    Science.gov (United States)

    Weed, Douglas L

    2018-05-01

    The purpose of this article was to rethink and resurrect Austin Bradford Hill's "criterion" of analogy as an important consideration in causal inference. In epidemiology today, analogy is either completely ignored (e.g., in many textbooks), or equated with biologic plausibility or coherence, or aligned with the scientist's imagination. None of these examples, however, captures Hill's description of analogy. His words suggest that there may be something gained by contrasting two bodies of evidence, one from an established causal relationship, the other not. Coupled with developments in the methods of systematic assessments of evidence-including but not limited to meta-analysis-analogy can be restructured as a key component in causal inference. This new approach will require that a collection-a library-of known cases of causal inference (i.e., bodies of evidence involving established causal relationships) be developed. This library would likely include causal assessments by organizations such as the International Agency for Research on Cancer, the National Toxicology Program, and the United States Environmental Protection Agency. In addition, a process for describing key features of a causal relationship would need to be developed along with what will be considered paradigm cases of causation. Finally, it will be important to develop ways to objectively compare a "new" body of evidence with the relevant paradigm case of causation. Analogy, along with all other existing methods and causal considerations, may improve our ability to identify causal relationships. Copyright © 2018 Elsevier Inc. All rights reserved.

  7. Overview of the Human Exploration Research Analog (HERA)

    Science.gov (United States)

    Neigut, J.

    2015-01-01

    In 2013, the Human Research Program at NASA began developing a new confinement analog specifically for conducting research to investigate the effects of confinement on the human system. The HERA (Human Exploration Research Analog) habitat has been used for both 7 and 14 day missions to date to examine and mitigate exploration risks to enable safe, reliable and productive human space exploration. This presentation will describe how the Flight Analogs Project developed the HERA facility and the infrastructure to suit investigator requirements for confinement research and in the process developed a new approach to analog utilization and a new state of the art analog facility. Details regarding HERA operations will be discussed including specifics on the mission simulation utilized for the current 14-day campaign, the specifics of the facility (total volume, overall size, hardware), and the capabilities available to researchers. The overall operational philosophy, mission fidelity including timeline, schedule pressures and cadence, and development and implementation of mission stressors will be presented. Research conducted to date in the HERA has addressed risks associated with behavioral health and performance, human physiology, as well as human factors. This presentation will conclude with a discussion of future research plans for the HERA, including infrastructure improvements and additional research capabilities planned for the upcoming 30-day missions in 2016.

  8. Analogical reasoning in schizophrenic delusions.

    Science.gov (United States)

    Simpson, Jane; Done, D John

    2004-09-01

    Reasoning ability has often been argued to be impaired in people with schizophrenic delusions, although evidence for this is far from convincing. This experiment examined the analogical reasoning abilities of several groups of patients, including non-deluded and deluded schizophrenics, to test the hypothesis that performance by the deluded schizophrenic group would be impaired. Eleven deluded schizophrenics, 10 depressed subjects, seven non-deluded schizophrenics and 16 matched non-psychiatric controls, who were matched on a number of key variables, were asked to solve an analogical reasoning task. Performance by the deluded schizophrenic group was certainly impaired when compared with the depressed and non-psychiatric control groups though less convincingly so when compared with the non-deluded schizophrenic group. The impairment shown by the deluded schizophrenic group seemed to occur at the initial stage of the reasoning task. The particular type of impairment shown by the deluded subjects was assessed in relation to other cognitive problems already researched and the implications of these problems on reasoning tasks and theories of delusions was discussed.

  9. Reliability of analog quantum simulation

    Energy Technology Data Exchange (ETDEWEB)

    Sarovar, Mohan [Sandia National Laboratories, Digital and Quantum Information Systems, Livermore, CA (United States); Zhang, Jun; Zeng, Lishan [Shanghai Jiao Tong University, Joint Institute of UMich-SJTU, Key Laboratory of System Control and Information Processing (MOE), Shanghai (China)

    2017-12-15

    Analog quantum simulators (AQS) will likely be the first nontrivial application of quantum technology for predictive simulation. However, there remain questions regarding the degree of confidence that can be placed in the results of AQS since they do not naturally incorporate error correction. Specifically, how do we know whether an analog simulation of a quantum model will produce predictions that agree with the ideal model in the presence of inevitable imperfections? At the same time there is a widely held expectation that certain quantum simulation questions will be robust to errors and perturbations in the underlying hardware. Resolving these two points of view is a critical step in making the most of this promising technology. In this work we formalize the notion of AQS reliability by determining sensitivity of AQS outputs to underlying parameters, and formulate conditions for robust simulation. Our approach naturally reveals the importance of model symmetries in dictating the robust properties. To demonstrate the approach, we characterize the robust features of a variety of quantum many-body models. (orig.)

  10. A novel natural analog in situ stabilization agent

    International Nuclear Information System (INIS)

    Shaw, P.

    1995-01-01

    This report summarizes the laboratory-scale test results on a synthetic analog of natural hematite cement for potential as an in situ treatment and stabilization agent for buried hazardous and radioactive waste. The concept is based on the principle that the ideal waste isolation materials are synthetic analogs of those natural encapsulating materials (cements), which are in equilibrium with the environment in which they occur. If equilibrium is achieved, then such materials will remain intact as long as the natural environment remains unchanged. The specific waste application is long-term stabilization of transuranic-contaminated waste pits and trenches at the Idaho National Engineering Laboratory (INEL). Six properties of the natural analog agent and resulting wasteforms are discussed to access the agent's effectiveness and implementability: hydraulic conductivity; compressive strength; mineralogy and microstructure; compatibility with possible waste materials, nitrates, machine cutting oil, and metallic iron; leachability of hazardous metals; and field application parameters. Data indicated that the iron waste encapsulation materials tested are appropriate choices for buried waste mixed with INEL soil. Iron oxide/gypsum INEL soil wasteforms have hydraulic conductivity values close to the regulatory limit. Wasteforms with soil and wastes have compressive strength greater than the regulatory minimum. Gypsum/iron oxide removes hazardous metals from solution by adsorption and would pass Toxicity Characteristic Leaching Procedure limits for most toxic metals. It appears to be chemically and physically inert with respect to the bulk of the waste materials likely to be found at INEL, and has properties conducive to jet grouting

  11. Digitally-assisted analog and RF CMOS circuit design for software-defined radio

    CERN Document Server

    Okada, Kenichi

    2011-01-01

    This book describes the state-of-the-art in RF, analog, and mixed-signal circuit design for Software Defined Radio (SDR). It synthesizes for analog/RF circuit designers the most important general design approaches to take advantage of the most recent CMOS technology, which can integrate millions of transistors, as well as several real examples from the most recent research results.

  12. Air oxidation of Zr65Cu17.5Ni10Al7.5 in its amorphous and supercooled liquid states, studied by thermogravimetric analysis

    International Nuclear Information System (INIS)

    Dhawan, A.; Sharma, S.K.; Raetzke, K.; Faupel, F.

    2003-01-01

    The oxidation behaviour of the bulk amorphous alloy Zr 65 Cu 17.5 Ni 10 Al 7.5 was studied in air at various temperatures in the temperature range 591-732 K using a thermogravimetric analyser (TGA). The oxidation kinetics of the alloy obeys the parabolic rate law showing two different linear regions (in the plots of mass gain versus square root of oxidation time) which are attributed to the amorphous and the supercooled liquid states of the alloy. The value of the activation energy Q for the amorphous state as calculated from the temperature dependence of the rate constants is found to be 1.80±0.1 eV and the corresponding value obtained for the supercooled liquid state is 1.20±0.1 eV. It is suggested that the rate controlling process during oxidation of the amorphous state is the back-diffusion of Ni, and possibly Cu also, while the oxidation in the supercooled liquid state is dominated by the inward diffusion of oxygen. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Speciation of the oxidation states of plutonium in aqueous solutions by UV/Vis spectroscopy, CE-ICP-MS and CE-RIMS

    International Nuclear Information System (INIS)

    Buerger, S.; Banik, N.L.; Buda, R.A.; Kratz, J.V.; Kuczewski, B.; Trautmann, N.

    2007-01-01

    For the speciation of the plutonium oxidation states in aqueous solutions, the online coupling of capillary electrophoresis (CE) with inductively coupled plasma mass spectrometry (ICP-MS) has been developed. Depending on the radius/electrical charge ratio, the oxidation states III, IV, V, and VI of plutonium are separated by CE, based on the different migration times through the capillary and are detected by ICP-MS. The detection limit is 20 ppb, i.e. 10 9 -10 10 atoms (10 -12 -10 -13 g) for one oxidation state with an uncertainty of the reproducibility of the migration times of ≤ 1% and ≤ 5% for the peak area. The redox kinetics of the different plutonium oxidation states in the presence of humic substances (humic and fulvic acid) have been studied. A relatively rapid reduction of Pu(VI) (10 to 1000 h) in contact with Gorleben fulvic or Aldrich humic acid could be observed, depending on the pH of the solution. Furthermore, at pH=1, a reduction to Pu(III) and Pu(IV) in a mixture of all four oxidation states in contact with Gorleben fulvic acid after one month has been observed. In order to improve the sensitivity of the CE method, the offline coupling of CE to resonance ionization mass spectrometry (RIMS) has been explored. First applications of this new speciation method are presented. (orig.)

  14. Tin Oxide Nanowires: The Influence of Trap States on Ultrafast Carrier Relaxation

    Directory of Open Access Journals (Sweden)

    Zervos Matthew

    2009-01-01

    Full Text Available Abstract We have studied the optical properties and carrier dynamics in SnO2nanowires (NWs with an average radius of 50 nm that were grown via the vapor–liquid solid method. Transient differential absorption measurements have been employed to investigate the ultrafast relaxation dynamics of photogenerated carriers in the SnO2NWs. Steady state transmission measurements revealed that the band gap of these NWs is 3.77 eV and contains two broad absorption bands. The first is located below the band edge (shallow traps and the second near the center of the band gap (deep traps. Both of these absorption bands seem to play a crucial role in the relaxation of the photogenerated carriers. Time resolved measurements suggest that the photogenerated carriers take a few picoseconds to move into the shallow trap states whereas they take ~70 ps to move from the shallow to the deep trap states. Furthermore the recombination process of electrons in these trap states with holes in the valence band takes ~2 ns. Auger recombination appears to be important at the highest fluence used in this study (500 μJ/cm2; however, it has negligible effect for fluences below 50 μJ/cm2. The Auger coefficient for the SnO2NWs was estimated to be 7.5 ± 2.5 × 10−31 cm6/s.

  15. SURFACE AND LIGHTNING SOURCES OF NITROGEN OXIDES OVER THE UNITED STATES: MAGNITUDES, CHEMICAL EVOLUTION, AND OUTFLOW

    Science.gov (United States)

    We use observations from two aircraft during the ICARTT campaign over the eastern United States and North Atlantic during summer 2004, interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem) to test current understanding of regional sources, chemical evolution...

  16. Nanoscale probing of bandgap states on oxide particles using electron energy-loss spectroscopy.

    Science.gov (United States)

    Liu, Qianlang; March, Katia; Crozier, Peter A

    2017-07-01

    Surface and near-surface electronic states were probed with nanometer spatial resolution in MgO and TiO 2 anatase nanoparticles using ultra-high energy resolution electron energy-loss spectroscopy (EELS) coupled to a scanning transmission electron microscope (STEM). This combination allows the surface electronic structure determined with spectroscopy to be correlated with nanoparticle size, morphology, facet etc. By acquiring the spectra in aloof beam mode, radiation damage to the surface can be significantly reduced while maintaining the nanometer spatial resolution. MgO and TiO 2 showed very different bandgap features associated with the surface/sub-surface layer of the nanoparticles. Spectral simulations based on dielectric theory and density of states models showed that a plateau feature found in the pre-bandgap region in the spectra from (100) surfaces of 60nm MgO nanocubes is consistent with a thin hydroxide surface layer. The spectroscopy shows that this hydroxide species gives rise to a broad filled surface state at 1.1eV above the MgO valence band. At the surfaces of TiO 2 nanoparticles, pronounced peaks were observed in the bandgap region, which could not be well fitted to defect states. In this case, the high refractive index and large particle size may make Cherenkov or guided light modes the likely causes of the peaks. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Effect of additions of cerium, lanthanum, and zirconium on the state of plantinum and the activity of aluminoplatinum catalysts for the complete oxidation of hydrocarbons

    International Nuclear Information System (INIS)

    Drozdov, V.A.; Davydov, A.A.; Popovskii, V.V.; Tsyrul'nikov, P.G.

    1986-01-01

    It is shown from an analysis of the diffuse reflectance spectra that additions of cerium, lanthanum or zirconium to aluminoplatinum catalyst stabilize the platinum in an oxidized state. This leads to a change in the specific catalytic activity (SCA) towards the total oxidation of methane and butane. The SCA of modified, reduced samples is greater than the SCA of samples that were calcined in air. This is because of the greater activity of metallic platinum compared to the ionic form

  18. Mn K-edge XANES spectroscopy of photosynthetic water oxidation enzyme in the S0-, S1-, S2- and S3-states induced by flash excitation

    International Nuclear Information System (INIS)

    Ono, Taka-aki; Noguchi, Takumi; Inoue, Yorinao; Kusunoki, Masami; Matsushita, Tadashi; Oyanagi, Hiroyuki.

    1993-01-01

    Electronic and structural rearrangement of the Mn-cluster during the four step oxidation of water in photosynthetic oxygen evolution was studied by XANES spectroscopy. The Mn K-edge energy of the spectrum was changed with flash number to show a clear quadruple oscillation, indicating a periodic change in oxidation and electronic state of the Mn-cluster depending on Joliot and Kok's oxygen clock. (author)

  19. Electroencephalogram, cognitive state, psychological disorders, clinical symptom, and oxidative stress in horticulture farmers exposed to organophosphate pesticides.

    Science.gov (United States)

    Bayrami, Mansour; Hashemi, Touraj; Malekirad, Ali Akbar; Ashayeri, Hassan; Faraji, Fardin; Abdollahi, Mohammad

    2012-02-01

    The aim of this paper was to study the toxicity of organophosphate (OP) pesticides in exposed farmers for electroencephalography, cognitive state, psychological disorders, clinical symptom, oxidative stress, acetylcholinesterase, and DNA damage. A comparative cross-sectional analysis was carried out in 40 horticulture farmers who were exposed to OPs in comparison to a control group containing 40 healthy subjects with the same age and sex and education level. Lipid peroxidation (LPO), superoxide dismutase (SOD), catalase, glutathione peroxidase, DNA damage, total antioxidant capacity (TAC), total thiol molecules, and acetylcholinesterase (AChE) activity were measured in the blood of subjects. Clinical examination and complete blood test were undertaken in order to record any abnormal sign or symptoms. Cognitive function, psychological symptoms, and psychological distress were examined and recorded. Comparing with controls, the farmers showed higher blood levels of SOD and LPO while their TAC decreased. Farmers showed clinical symptoms such as eczema, breathing muscle weakness, nausea, and saliva secretion. Regarding cognitive function, the orientation, registration, attention and calculation, recall, and language were not significantly different in farmers and controls. Among examinations for psychological distress, only labeled somatization was significantly higher in farmers. The present findings indicate that oxidative stress and inhibition of AChE can be seen in chronically OP-exposed people but incidence of neuropsychological disorders seems a complex multivariate phenomenon that might be seen in long-term high-dose exposure situations. Use of supplementary antioxidants would be useful in the treatment of farmers.

  20. Steady-state oxidation of cholesterol catalyzed by cholesterol oxidase in lipid bilayer membranes on platinum electrodes

    International Nuclear Information System (INIS)

    Bokoch, Michael P.; Devadoss, Anando; Palencsar, Mariela S.; Burgess, James D.

    2004-01-01

    Cholesterol oxidase is immobilized in electrode-supported lipid bilayer membranes. Platinum electrodes are initially modified with a self-assembled monolayer of thiolipid. A vesicle fusion method is used to deposit an outer leaflet of phospholipids onto the thiolipid monolayer forming a thiolipid/lipid bilayer membrane on the electrode surface. Cholesterol oxidase spontaneously inserts into the electrode-supported lipid bilayer membrane from solution and is consequently immobilized to the electrode surface. Cholesterol partitions into the membrane from buffer solutions containing cyclodextrin. Cholesterol oxidase catalyzes the oxidation of cholesterol by molecular oxygen, forming hydrogen peroxide as a product. Amperometric detection of hydrogen peroxide for continuous solution flow experiments are presented, where flow was alternated between cholesterol solution and buffer containing no cholesterol. Steady-state anodic currents were observed during exposures of cholesterol solutions ranging in concentration from 10 to 1000 μM. These data are consistent with the Michaelis-Menten kinetic model for oxidation of cholesterol as catalyzed by cholesterol oxidase immobilized in the lipid bilayer membrane. The cholesterol detection limit is below 1 μM for cholesterol solution prepared in buffered cyclodextrin. The response of the electrodes to low density lipoprotein solutions is increased upon addition of cyclodextrin. Evidence for adsorption of low density lipoprotein to the electrode surface is presented

  1. Nickel Oxide (NiO nanoparticles prepared by solid-state thermal decomposition of Nickel (II schiff base precursor

    Directory of Open Access Journals (Sweden)

    Aliakbar Dehno Khalaji

    2015-06-01

    Full Text Available In this paper, plate-like NiO nanoparticles were prepared by one-pot solid-state thermal decomposition of nickel (II Schiff base complex as new precursor. First, the nickel (II Schiff base precursor was prepared by solid-state grinding using nickel (II nitrate hexahydrate, Ni(NO32∙6H2O, and the Schiff base ligand N,N′-bis-(salicylidene benzene-1,4-diamine for 30 min without using any solvent, catalyst, template or surfactant. It was characterized by Fourier Transform Infrared spectroscopy (FT-IR and elemental analysis (CHN. The resultant solid was subsequently annealed in the electrical furnace at 450 °C for 3 h in air atmosphere. Nanoparticles of NiO were produced and characterized by X-ray powder diffraction (XRD at 2θ degree 0-140°, FT-IR spectroscopy, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The XRD and FT-IR results showed that the product is pure and has good crystallinity with cubic structure because no characteristic peaks of impurity were observed, while the SEM and TEM results showed that the obtained product is tiny, aggregated with plate-like shape, narrow size distribution with an average size between 10-40 nm. Results show that the solid state thermal decomposition method is simple, environmentally friendly, safe and suitable for preparation of NiO nanoparticles. This method can also be used to synthesize nanoparticles of other metal oxides.

  2. A Singular Perturbation Problem for Steady State Conversion of Methane Oxidation in Reverse Flow Reactor

    Directory of Open Access Journals (Sweden)

    Aang Nuryaman

    2012-11-01

    Full Text Available The governing equations describing the methane oxidation process in reverse flow reactor are given by a set of convective-diffusion equations with a nonlinear reaction term, where temperature and methane conversion are dependent variables. In this study, the process is assumed to be one-dimensional pseudo homogeneous model and takes place with a certain reaction rate in which the whole process of reactor is still workable. Thus, the reaction rate can proceed at a fixed temperature. Under this condition, we restrict ourselves to solve the equations for the conversion only. From the available data, it turns out that the ratio of the diffusion term to the reaction term is small. Hence, this ratio is considered as small parameter in our model and this leads to a singular perturbation problem. In the vicinity of small parameter in front of higher order term, the numerical difficulties will be found. Here, we present an analytical solution by means of matched asymptotic expansions. Result shows that, up to and including the first order of approximation, the solution is in agreement with the exact and numerical solutions of the boundary value problem.

  3. Simulation of the steady-state behaviour of a new design of a single planar Solid Oxide Fuel Cell

    Directory of Open Access Journals (Sweden)

    Pianko-Oprych Paulina

    2016-03-01

    Full Text Available The aim of the work was to develop a mathematical model for computing the steady-state voltage – current characteristics of a planar Solid Oxide Fuel Cell and to determine the performance of a new SOFC design. The design involves cross-flow bipolar plates. Each of the bipolar plates has an air channel system on one side and a fuel channel system on the other side. The proposed model was developed using the ANSYS-Fluent commercial Computational Fluid Dynamics (CFD software supported by additional Fuel Cell module. The results confirm that the model can well simulate the diagonal current path. The effects of temperature and gas flow through the channels and a Membrane Electrode Assembly (MEA structure were taken into account. It was shown that a significant increase of the MEA temperature at high current density can lead to hot spots formation and hence electrode damage.

  4. All-solid-state flexible supercapacitors based on highly dispersed polypyrrole nanowire and reduced graphene oxide composites.

    Science.gov (United States)

    Yu, Chenfei; Ma, Peipei; Zhou, Xi; Wang, Anqi; Qian, Tao; Wu, Shishan; Chen, Qiang

    2014-10-22

    Highly dispersed polypyrrole nanowires are decorated on reduced graphene oxide sheets using a facile in situ synthesis route. The prepared composites exhibit high dispersibility, large effective surface area, and high electric conductivity. All-solid-state flexible supercapacitors are assembled based on the prepared composites, which show excellent electrochemical performances with a specific capacitance of 434.7 F g(-1) at a current density of 1 A g(-1). The as-fabricated supercapacitor also exhibits excellent cycling stability (88.1% capacitance retention after 5000 cycles) and exceptional mechanical flexibility. In addition, outstanding power and energy densities were obtained, demonstrating the significant potential of prepared material for flexible and portable energy storage devices.

  5. Eco-friendly wood-based solid-state flexible supercapacitors from wood transverse section slice and reduced graphene oxide

    Science.gov (United States)

    Lv, Shaoyi; Fu, Feng; Wang, Siqun; Huang, Jingda; Hu, La

    2015-07-01

    An interesting wood-based all-solid-state supercapacitor is produced using reduced graphene oxide (RGO) coated on wood transverse section slice (WTSS) as electrode material by means of a low-cost, eco-friendly, and simple method for the first time. The RGO-coated WTSS electrode has a porous 3D honeycomb framework due to the hierarchical cellular structure of the WTSS substrate and can function as an electrolyte reservoir. This special construction endows this novel electrode with good areal capacitance (102 mF cm-2) and excellent cyclic stability (capacitance retention of 98.9% after 5000 cycles). In addition, the supercapacitors exhibit good mechanical flexibility and preserve almost constant capacitive behavior under different bending conditions. Our study introduces a new and eco-friendly material design for electrodes in future flexible energy storage devices that closely resemble natural materials. [Figure not available: see fulltext.

  6. Synthesis and Electrochemistry of Li3MnO4: Mn in the +5 OxidationState

    Energy Technology Data Exchange (ETDEWEB)

    Saint, Juliette.A.; Doeff, Marca M.; Reed, John

    2007-06-19

    Computational and experimental work directed at exploringthe electrochemical properties of tetrahedrally coordinated Mn in the +5oxidation state is presented. Specific capacities of nearly 700 mAh/g arepredicted for the redox processes of LixMnO4 complexes based on twotwo-phase reactions. One is topotactic extractionof Li from Li3MnO4 toform LiMnO4 and the second is topotactic insertion of Li into Li3MnO4 toform Li5MnO4. In experiments, it is found that the redox behavior ofLi3MnO4 is complicated by disproportionation of Mn5+ in solution to formMn4+ and Mn7+ and byother irreversible processes; although an initialcapacity of about 275 mAh/g in lithiumcells was achieved. Strategiesbased on structural considerations to improve the electrochemicalproperties of MnO4n- complexes are given.

  7. Influence of Battery Parametric Uncertainties on the State-of-Charge Estimation of Lithium Titanate Oxide-Based Batteries

    DEFF Research Database (Denmark)

    Stroe, Ana-Irina; Meng, Jinhao; Stroe, Daniel-Ioan

    2018-01-01

    to describe the battery dynamics. The SOC estimation method proposed in this paper is based on an Extended Kalman Filter (EKF) and nonlinear battery model which was parameterized using extended laboratory tests performed on several 13 Ah lithium titanate oxide (LTO)-based lithium-ion batteries. The developed......State of charge (SOC) is one of the most important parameters in battery management systems, as it indicates the available battery capacity at every moment. There are numerous battery model-based methods used for SOC estimation, the accuracy of which depends on the accuracy of the model considered...... a sensitivity analysis it was showed that the SOC and voltage estimation error are only slightly dependent on the variation of the battery model parameters with the SOC....

  8. Automatic activation of categorical and abstract analogical relations in analogical reasoning.

    Science.gov (United States)

    Green, Adam E; Fugelsang, Jonathan A; Dunbar, Kevin N

    2006-10-01

    We examined activation of concepts during analogical reasoning. Subjects made either analogical judgments or categorical judgments about four-word sets. After each four-word set, they named the ink color of a single word in a modified Stroop task. Words that referred to category relations were primed (as indicated by longer response times on Stroop color naming) subsequent to analogical judgments and categorical judgments. This finding suggests that activation of category concepts plays a fundamental role in analogical thinking. When colored words referred to analogical relations, priming occurred subsequent to analogical judgments, but not to categorical judgments, even though identical four-word stimuli were used for both types of judgments. This finding lends empirical support to the hypothesis that, when people comprehend the analogy between two items, they activate an abstract analogical relation that is distinct from the specific content items that compose the analogy.

  9. Interval training in the fed or fasted state improves body composition and muscle oxidative capacity in overweight women.

    Science.gov (United States)

    Gillen, Jenna B; Percival, Michael E; Ludzki, Alison; Tarnopolsky, Mark A; Gibala, Martin J

    2013-11-01

    To investigate the effects of low-volume high-intensity interval training (HIT) performed in the fasted (FAST) versus fed (FED) state on body composition, muscle oxidative capacity, and glycemic control in overweight/obese women. Sixteen women (27 ± 8 years, BMI: 29 ± 6 kg/m(2) , VO2peak : 28 ± 3 ml/kg/min) were assigned to either FAST or FED (n = 8 each) and performed 18 sessions of HIT (10× 60-s cycling efforts at ∼90% maximal heart rate, 60-s recovery) over 6 weeks. There was no significant difference between FAST and FED for any measured variable. Body mass was unchanged following training; however, dual energy X-ray absorptiometry revealed lower percent fat in abdominal and leg regions as well as the whole body level (main effects for time, P ≤ 0.05). Fat-free mass increased in leg and gynoid regions (P ≤ 0.05). Resting muscle biopsies revealed a training-induced increase in mitochondrial capacity as evidenced by increased maximal activities of citrate synthase and β-hydroxyacyl-CoA dehydrogenase (P ≤ 0.05). There was no change in insulin sensitivity, although change in insulin area under the curve was correlated with change in abdominal percent fat (r = 0.54, P ≤ 0.05). Short-term low-volume HIT is a time-efficient strategy to improve body composition and muscle oxidative capacity in overweight/obese women, but fed- versus fasted-state training does not alter this response. Copyright © 2013 The Obesity Society.

  10. Magnetotransport investigations of the two-dimensional metallic state in silicon metal-oxid-semiconductor structures

    International Nuclear Information System (INIS)

    Prinz, A.

    2002-03-01

    For more than two decades it was the predominant view among the physical community that the every two-dimensional (2D) disordered electron system becomes insulating as the temperature approaches the absolute zero temperature (0 Kelvin or -273.15 o C). Two-dimensional means that the movement of the charge carriers is confined in one direction by a potential so that the carriers can move freely only perpendicular to the confinement. The most famous physical realization of a 2D system is the silicon metal-oxide-semiconductor field effect transistor (Si-MOSFET). It is one of the basic elements of most electronic devices in our daily life. The working principle is very simple. Charges are attracted to the semiconductor-oxide interface by an electric field applied between the metallic gate and the semiconductor, so that a 2D conductive channel is formed. The charge density can be adjusted by the voltage from zero up to 10 13 cm -2 . In 1994 Kravchenko and coworkers made a very important discovery. They studied high mobility Si-MOSFETs and found that for densities below a certain critical value, nc, the resistivity increases as the temperature is decreased below 2 K, whereas for densities above $n c $ the resistivity decreases unexpectedly. The transition from insulating to metallic behavior, known as metal-insulator transition (MIT), was obviously a contradiction to the commonly accepted theories which predict insulating behavior for any density. The insulating behavior is a consequence of the wave properties of electrons which leads to interference in disordered media and thus to enhanced backscattering. In the subsequent years, experimental studies were performed on a variety of 2D systems, which qualitatively showed a similar behavior. All the investigated samples had one thing in common. The interaction energy between the carriers was considerable higher than their mean kinetic energy due to their movement in the 2D plane. Since the electron-electron interaction was

  11. Priming analogical reasoning with false memories.

    Science.gov (United States)

    Howe, Mark L; Garner, Sarah R; Threadgold, Emma; Ball, Linden J

    2015-08-01

    Like true memories, false memories are capable of priming answers to insight-based problems. Recent research has attempted to extend this paradigm to more advanced problem-solving tasks, including those involving verbal analogical reasoning. However, these experiments are constrained inasmuch as problem solutions could be generated via spreading activation mechanisms (much like false memories themselves) rather than using complex reasoning processes. In three experiments we examined false memory priming of complex analogical reasoning tasks in the absence of simple semantic associations. In Experiment 1, we demonstrated the robustness of false memory priming in analogical reasoning when backward associative strength among the problem terms was eliminated. In Experiments 2a and 2b, we extended these findings by demonstrating priming on newly created homonym analogies that can only be solved by inhibiting semantic associations within the analogy. Overall, the findings of the present experiments provide evidence that the efficacy of false memory priming extends to complex analogical reasoning problems.

  12. Neural correlates of creativity in analogical reasoning.

    Science.gov (United States)

    Green, Adam E; Kraemer, David J M; Fugelsang, Jonathan A; Gray, Jeremy R; Dunbar, Kevin N

    2012-03-01

    Brain-based evidence has implicated the frontal pole of the brain as important for analogical mapping. Separately, cognitive research has identified semantic distance as a key determinant of the creativity of analogical mapping (i.e., more distant analogies are generally more creative). Here, we used functional magnetic resonance imaging to assess brain activity during an analogy generation task in which we varied the semantic distance of analogical mapping (as derived quantitatively from a latent semantic analysis). Data indicated that activity within an a priori region of interest in left frontopolar cortex covaried parametrically with increasing semantic distance, even after removing effects of task difficulty. Results implicate increased recruitment of frontopolar cortex as a mechanism for integrating semantically distant information to generate solutions in creative analogical reasoning. 2012 APA, all rights reserved

  13. An emergent approach to analogical inference

    Science.gov (United States)

    Thibodeau, Paul H.; Flusberg, Stephen J.; Glick, Jeremy J.; Sternberg, Daniel A.

    2013-03-01

    In recent years, a growing number of researchers have proposed that analogy is a core component of human cognition. According to the dominant theoretical viewpoint, analogical reasoning requires a specific suite of cognitive machinery, including explicitly coded symbolic representations and a mapping or binding mechanism that operates over these representations. Here we offer an alternative approach: we find that analogical inference can emerge naturally and spontaneously from a relatively simple, error-driven learning mechanism without the need to posit any additional analogy-specific machinery. The results also parallel findings from the developmental literature on analogy, demonstrating a shift from an initial reliance on surface feature similarity to the use of relational similarity later in training. Variants of the model allow us to consider and rule out alternative accounts of its performance. We conclude by discussing how these findings can potentially refine our understanding of the processes that are required to perform analogical inference.

  14. The oxidation state of Fe in MORB glasses and the oxygen fugacity of the upper mantle

    Science.gov (United States)

    Cottrell, Elizabeth; Kelley, Katherine A.

    2011-05-01

    Micro-analytical determination of Fe3+/∑Fe ratios in mid-ocean ridge basalt (MORB) glasses using micro X-ray absorption near edge structure (μ-XANES) spectroscopy reveals a substantially more oxidized upper mantle than determined by previous studies. Here, we show that global MORBs yield average Fe3+/∑Fe ratios of 0.16 ± 0.01 (n = 103), which trace back to primary MORB melts equilibrated at the conditions of the quartz-fayalite-magnetite (QFM) buffer. Our results necessitate an upward revision of the Fe3+/∑Fe ratios of MORBs, mantle oxygen fugacity, and the ferric iron content of the mantle relative to previous wet chemical determinations. We show that only 0.01 (absolute, or Co-variations of Fe3+/∑Fe ratios in global MORB with indices of low-pressure fractional crystallization are consistent with Fe3+ behaving incompatibly in shallow MORB magma chambers. MORB Fe3+/∑Fe ratios do not, however, vary with indices of the extent of mantle melting (e.g., Na2O(8)) or water concentration. We offer two hypotheses to explain these observations: The bulk partition coefficient of Fe3+ may be higher during peridotite melting than previously thought, and may vary with temperature, or redox exchange between sulfide and sulfate species could buffer mantle melting at ~ QFM. Both explanations, in combination with the measured MORB Fe3+/∑Fe ratios, point to a fertile MORB source with greater than 0.3 wt.% Fe2O3.

  15. Thermodynamic properties of ternary oxides in the system Ba-Fe-O using solid-state electrochemical cells with oxide and fluoride ion conducting electrolytes

    Science.gov (United States)

    Rakshit, S. K.; Parida, S. C.; Singh, Ziley; Prasad, R.; Venugopal, V.

    2004-04-01

    The standard molar Gibbs energy of formations of BaFe 12O 19(s), BaFe 2O 4(s), Ba 2Fe 2O 5(s), Ba 3Fe 2O 6(s) and Ba 5Fe 2O 8(s) have been determined using solid-state electrochemical technique employing CaF 2(s) as an electrolyte. The reversible e.m.f. values have been measured in the temperature range from 970 to 1151 K. The oxygen chemical potential corresponding to three phase equilibria involving technologically important compound BaFe 12O 19(s) has been determined using solid-state electrochemical technique employing CSZ as an electrolyte from 1048 to 1221 K. The values of Δ fGm0( T) for the above ternary oxides are given by ΔfG m0( BaFe12O19, s)/ kJ mol -1(±0.6)=-5431.3+1.5317 (T/ K) (970⩽T/ K⩽1151) ΔfG m0( BaFe2O4, s)/ kJ mol -1(±1.3)=-1461.4+0.3745 (T/ K) (970⩽T/ K⩽1151) ΔfG m0( Ba2Fe2O5, s)/ kJ mol -1(±1.4)=-2038.3+0.4433 (T/ K) (970⩽T/ K⩽1149) ΔfG m0( Ba3Fe2O6, s)/ kJ mol -1(±1.5)=-2700.1+0.6090 (T/ K) (969⩽T/ K⩽1150) and ΔfG m0( Ba5Fe2O8, s)/ kJ mol -1(±1.6)=-3984.1+0.9300 (T/ K) (973⩽T/ K⩽1150) The uncertainty estimates for Δ fGm0 includes the standard deviation in the e.m.f. and uncertainty in the data taken from the literature. An isothermal oxygen potential diagram for the system Ba-Fe-O was constructed at 1100 K based on the thermodynamic data obtained in this study.

  16. Nyquist AD Converters, Sensor Interfaces, and Robustness Advances in Analog Circuit Design, 2012

    CERN Document Server

    Baschirotto, Andrea; Steyaert, Michiel

    2013-01-01

    This book is based on the presentations during the 21st workshop on Advances in Analog Circuit Design.  Expert designers provide readers with information about a variety of topics at the frontier of analog circuit design, including Nyquist analog-to-digital converters, capacitive sensor interfaces, reliability, variability, and connectivity.  This book serves as a valuable reference to the state-of-the-art, for anyone involved in analog circuit research and development.  Provides a state-of-the-art reference in analog circuit design, written by experts from industry and academia; Presents material in a tutorial-based format; Includes coverage of Nyquist A/D converters, capacitive sensor interfaces, reliability, variability, and connectivity.

  17. Analog techniques in CEBAF's RF control system

    International Nuclear Information System (INIS)

    Hovater, C.; Fugitt, J.

    1989-01-01

    Recent developments in high-speed analog technology have progressed into the areas of traditional RF technology. Diode related devices are being replaced by analog IC's in the CEBAF RF control system. Complex phase modulators and attenuators have been successfully tested at 70 MHz. They have three advantages over existing technology: lower cost, less temperature sensitivity, and more linearity. RF signal conditioning components and how to implement the new analog IC's will be covered in this paper. 4 refs., 5 figs

  18. Analog techniques in CEBAF'S RF control system

    International Nuclear Information System (INIS)

    Hovater, C.; Fugitt, J.

    1989-01-01

    Recent developments in high-speed analog technology have progressed into the areas of traditional rf technology. Diode-related devices are being replaced by analog IC's in the CEBAF rf control system. Complex phase modulators and attenuators have been successfully tested at 70 MHz. They have three advantages over existing technology: lower cost, less temperature sensitivity, and more linearity. Rf signal conditioning components and how to implement the new analog IC's will be covered in this paper. 4 refs., 5 figs

  19. Design and Analysis of Reconfigurable Analog System

    Science.gov (United States)

    2011-02-01

    34010010" �" �" �" �" �" �" �±" N3 N2 N± P1 P2 P3 * Current sources $RR = 1; *Ramp Rate (slope of the...2008/12/12/31e83bac-500f-4182- acca -4d360295fd9c.pdf, Analog Devices, Analog Dialogue 39-06, June 2005. [15] D. A. Johns, K. Martin "Analog Integrated

  20. Transition Metal Oxides for the Oxygen Reduction Reaction: Influence of the Oxidation States of the Metal and its Position on the Periodic Table.

    Science.gov (United States)

    Toh, Rou Jun; Sofer, Zdeněk; Pumera, Martin

    2015-11-16

    Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.