WorldWideScience

Sample records for fast electron transfer

  1. Electron-electron Thomas peak in fast transfer ionization

    International Nuclear Information System (INIS)

    Tolmanov, S. G.; McGuire, J. H.

    2000-01-01

    ''Thomas process'' is a name used for a family of singular two-step processes that can lead to electron transfer. The Thomas process of the ''second kind,'' occurring in reactions with both transfer and ionization, utilizes the e-e scattering in the second step, so this Thomas process requires the dynamics of the electron-electron interaction. We calculate numerically the second order element of an S matrix and corresponding cross sections for the transfer ionization process. We find that the position and shape of the Thomas peak depend on both electron-electron and the electron-nucleus interaction. Also the direct and exchange amplitudes are equal at the peak position. We test the peaking approximation used for transfer ionization. Our results can be compared to experimental results for p + +He→H+He 2+ +e - . (c) 2000 The American Physical Society

  2. Electron-electron interaction and transfer ionization in fast ion-atom collisions

    International Nuclear Information System (INIS)

    Voitkiv, A B

    2008-01-01

    Recently it was pointed out that electron capture occurring in fast ion-atom collisions can proceed via a mechanism which earlier was not considered. In the present paper we study this mechanism in more detail. Similarly as in radiative capture, where the electron transfer occurs due to the interaction with the radiation field and proceeds via emission of a photon, within this mechanism the electron capture is caused by the interaction with another atomic electron leading mainly to the emission of the latter. In contrast to the electron-electron Thomas capture, this electron-electron (E-E) mechanism is basically a first-order one having similarities to the kinematic and radiative capture channels. It also possesses important differences with the latter two. Leading to transfer ionization, this first-order capture mechanism results in the electron emission mainly in the direction opposite to the motion of the projectile ion. The same, although less pronounced, feature is also characteristic for the momenta of the target recoil ions produced via this mechanism. It is also shown that the action of the E-E mechanism is clearly seen in recent experimental data on the transfer ionization in fast proton-helium collisions.

  3. Fast electron transfer through a single molecule natively structured redox protein

    DEFF Research Database (Denmark)

    Della Pia, Eduardo Antonio; Chi, Qijin; Macdonald, J. Emyr

    2012-01-01

    The electron transfer properties of proteins are normally measured as molecularly averaged ensembles. Through these and related measurements, proteins are widely regarded as macroscopically insulating materials. Using scanning tunnelling microscopy (STM), we present new measurements of the conduc...

  4. On the physics of electron transfer (drift) in the substance: about the reason of “abnormal” fast transfer of electrons in the plasma of tokamak and at known Bohm’s diffusion

    Science.gov (United States)

    Boriev, I. A.

    2018-03-01

    An analysis of the problem of so-called “abnormal” fast transfer of electrons in tokamak plasma, which turned out much faster than the result of accepted calculation, is given. Such transfer of hot electrons leads to unexpectedly fast destruction of the inner tokamak wall with ejection of its matter in plasma volume, what violates a condition of plasma confinement for controlled thermonuclear fusion. It is shown, taking into account real physics of electron drift in the gas (plasma) and using the conservation law for momentum of electron transfer (drift), that the drift velocity of elastically scattered electrons should be significantly greater than that of accepted calculation. The reason is that the relaxation time of the momentum of electron transfer, to which the electron drift velocity is proportional, is significantly greater (from 16 up to 4 times) than the electron free path time. Therefore, generally accepted replacement of the relaxation time, which is unknown a priori, by the electron free path time, leads to significant (16 times for thermal electrons) underestimation of electron drift velocity (mobility). This result means, that transfer of elastically (and isotropically) scattered electrons in the gas phase should be so fast, and corresponds to multiplying coefficient (16), introduced by D. Bohm to explain the observed by him “abnormal” fast diffusion of electrons.

  5. Electron transfer in proteins

    DEFF Research Database (Denmark)

    Farver, O; Pecht, I

    1991-01-01

    Electron migration between and within proteins is one of the most prevalent forms of biological energy conversion processes. Electron transfer reactions take place between active centers such as transition metal ions or organic cofactors over considerable distances at fast rates and with remarkable...... specificity. The electron transfer is attained through weak electronic interaction between the active sites, so that considerable research efforts are centered on resolving the factors that control the rates of long-distance electron transfer reactions in proteins. These factors include (in addition......-containing proteins. These proteins serve almost exclusively in electron transfer reactions, and as it turns out, their metal coordination sites are endowed with properties uniquely optimized for their function....

  6. Evidences from electron momentum spectroscopy for ultra-fast charge transfers and structural reorganizations in a floppy molecule: Ethanol

    International Nuclear Information System (INIS)

    Deleuze, Michael S; Hajgato, Balazs; Morini, Filippo

    2009-01-01

    Calculations of electron momentum distributions employing advanced Dyson orbital theories and statistical thermodynamics beyond the RRHO approximation fail to quantitatively reproduce the outermost momentum profile inferred from experiments on ethanol employing high resolution Electron Momentum Spectroscopy [1]. Study of the influence of nuclear dynamics in the initial ground state and final ionized state indicates that this discrepancy between theory and experiment reflects a charge transfer occurring during an ultra-fast dissociation of the ethanol radical cation into a methyl radical and H 2 C=O-H + .

  7. Fast multilevel radiative transfer

    International Nuclear Information System (INIS)

    Paletou, Frederic; Leger, Ludovick

    2007-01-01

    The vast majority of recent advances in the field of numerical radiative transfer relies on approximate operator methods better known in astrophysics as Accelerated Lambda-Iteration (ALI). A superior class of iterative schemes, in term of rates of convergence, such as Gauss-Seidel and successive overrelaxation methods were therefore quite naturally introduced in the field of radiative transfer by Trujillo Bueno and Fabiani Bendicho [A novel iterative scheme for the very fast and accurate solution of non-LTE radiative transfer problems. Astrophys J 1995;455:646]; it was thoroughly described for the non-LTE two-level atom case. We describe hereafter in details how such methods can be generalized when dealing with non-LTE unpolarised radiation transfer with multilevel atomic models, in monodimensional geometry

  8. Enzyme-immobilized SiO2-Si electrode: Fast interfacial electron transfer with preserved enzymatic activity

    Science.gov (United States)

    Wang, Gang; Yau, Siu-Tung

    2005-12-01

    The enzyme, glucose oxidase (GOx), is immobilized using electrostatic interaction on the native oxide of heavily doped n-type silicon. Voltammetric measurement shows that the immobilized GOx gives rise to a very fast enzyme-silicon interfacial electron transfer rate constant of 7.9s-1. The measurement also suggests that the enzyme retains its native conformation when immobilized on the silicon surface. The preserved native conformation of GOx is further confirmed by testing the enzymatic activity of the immobilized GOx using glucose. The GOx-immobilized silicon is shown to behave as a glucose sensor that detects glucose with concentrations as low as 50μM.

  9. Fast intramolecular electron transfer and dual fluorescence. Configurational change of the amino nitrogen (pyramidal→planar)

    International Nuclear Information System (INIS)

    Haar, Th. von der; Hebecker, A.; Il'Ichev, Yu.; Kuehnle, W.; Zachariasse, K. A.

    1996-01-01

    The fast excited state intramolecular charge transfer (ICT) and dual fluorescence observed with several 4-aminobenzonitriles is discussed. It is shown that the magnitude of the energy gap between the two lowest excited states determines the occurrence or absence of ICT. The photophysical behavior of a series of four 4-aminobenzonitriles in which the amino nitrogen atom is part of a four- to seven-membered heterocyclic ring, P4C to P7C, is studied by using time-resolved fluorescence measurements. The ICT rate constant strongly decreases with decreasing ring size. With P4C in diethyl ether ICT does not occur. This is attributed to the increase of the amino nitrogen inversion barrier with decreasing ring size. The change of the amino nitrogen from pyramidal to planar is considered to be an important reaction coordinate. The photophysics of the 4-aminobenzonitriles is different from that of other ICT systems such as donor/acceptor-substituted stilbenes and 9,9'-bianthryl, which are governed by the charge distribution and macroscopic Coulombic interaction in their CT states

  10. Electron transfer to sulfides:

    International Nuclear Information System (INIS)

    Meneses, Ana Belen; Antonello, Sabrina; Arevalo, Maria Carmen; Maran, Flavio

    2005-01-01

    The problem of characterizing the steps associated with the dissociative reduction of sulfides has been addressed. The electrochemical reduction of diphenylmethyl para-methoxyphenyl sulfide in N,N-dimethylformamide, on both glassy carbon and mercury electrodes, was chosen as a test system. The electrode process involves the slow heterogeneous outer-sphere electron transfer to the sulfide, the fast cleavage of the C-S bond, the reduction of the ensuing carbon radical, and the self-protonation triggered by the generation of the strong base Ph 2 CH - . The latter reaction is rather slow, in agreement with the large intrinsic barriers characterizing proton transfers between CH-acids and carbon bases. The dissociative reduction was studied in the presence of an exogenous acid. The results, obtained by convolution analysis, point to a stepwise DET mechanism in which the ET step is accompanied by rather large reorganization energy. Similar results were obtained on both electrode materials. Analysis of the heterogeneous electron transfer and associated C-S bond cleavage indicate that the reduction of this and other sulfides lies between the stepwise dissociative electron transfers leading to the formation of stiff π* radical anions and those going through the intermediacy of loose σ* radical anions

  11. Nonadiabatic anharmonic electron transfer

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, P. P. [Molecular Physics Research, 6547 Kristina Ursula Court, Falls Church, Virginia 22044 (United States)

    2013-03-28

    The effect of an inner sphere, local mode vibration on an electron transfer is modeled using the nonadiabatic transition probability (rate) expression together with both the anharmonic Morse and the harmonic oscillator potential. For an anharmonic inner sphere mode, a variational analysis uses harmonic oscillator basis functions to overcome the difficulties evaluating Morse-model Franck-Condon overlap factors. Individual matrix elements are computed with the use of new, fast, robust, and flexible recurrence relations. The analysis therefore readily addresses changes in frequency and/or displacement of oscillator minimums in the different electron transfer states. Direct summation of the individual Boltzmann weighted Franck-Condon contributions avoids the limitations inherent in the use of the familiar high-temperature, Gaussian form of the rate constant. The effect of harmonic versus anharmonic inner sphere modes on the electron transfer is readily seen, especially in the exoergic, inverted region. The behavior of the transition probability can also be displayed as a surface for all temperatures and values of the driving force/exoergicity {Delta}=-{Delta}G. The temperature insensitivity of the transfer rate is clearly seen when the exoergicity equals the collective reorganization energy ({Delta}={Lambda}{sub s}) along a maximum ln (w) vs. {Delta} ridge of the surface. The surface also reveals additional regions for {Delta} where ln (w) appears to be insensitive to temperature, or effectively activationless, for some kinds of inner sphere contributions.

  12. Electron transfer reactions

    CERN Document Server

    Cannon, R D

    2013-01-01

    Electron Transfer Reactions deals with the mechanisms of electron transfer reactions between metal ions in solution, as well as the electron exchange between atoms or molecules in either the gaseous or solid state. The book is divided into three parts. Part 1 covers the electron transfer between atoms and molecules in the gas state. Part 2 tackles the reaction paths of oxidation states and binuclear intermediates, as well as the mechanisms of electron transfer. Part 3 discusses the theories and models of the electron transfer process; theories and experiments involving bridged electron transfe

  13. Fast multilevel radiative transfer

    Science.gov (United States)

    Paletou, Frédéric; Léger, Ludovick

    2007-01-01

    The vast majority of recent advances in the field of numerical radiative transfer relies on approximate operator methods better known in astrophysics as Accelerated Lambda-Iteration (ALI). A superior class of iterative schemes, in term of rates of convergence, such as Gauss-Seidel and Successive Overrelaxation methods were therefore quite naturally introduced in the field of radiative transfer by Trujillo Bueno & Fabiani Bendicho (1995); it was thoroughly described for the non-LTE two-level atom case. We describe hereafter in details how such methods can be generalized when dealing with non-LTE unpolarised radiation transfer with multilevel atomic models, in monodimensional geometry.

  14. Fast transfer of shared data

    International Nuclear Information System (INIS)

    Timmer, C.; Abbott, D.J.; Heyes, W.G.; Jostizembski, E.; MacLeod, R.W.; Wolin, E.

    2000-01-01

    The Event Transfer system enables its users to produce events (data) and share them with other users by utilizing shared memory on either Solaris or Linux-based computers. Its design emphasizes speed, reliability, ease of use, and recoverability from crashes. In addition to fast local operation, the ET system allows network transfer of events. Using multi-threaded code based on POSIX threades and mutexes, a successful implementation was developed which allowed passing events over 500 kHz on a 4 cpu Sun workstation and 150 kHz on a dual cpu PC

  15. Enabling fast electron transfer through both bacterial outer-membrane redox centers and endogenous electron mediators by polyaniline hybridized large-mesoporous carbon anode for high-performance microbial fuel cells

    International Nuclear Information System (INIS)

    Zou, Long; Qiao, Yan; Zhong, Canyu; Li, Chang Ming

    2017-01-01

    Both physical structure and chemical property of an electrode play critical roles in extracellular electron transfer from microbes to electrodes in microbial fuel cells (MFCs). Herein a novel polyaniline hybridized large mesoporous carbon (PANI-LMC) anode is fabricated from natural biomass by nanostructured CaCO 3 template-assisted carbonization followed by in situ chemical polymerizing PANI to enable fast extracellular electron transfer, in which the LMC with rich disorder-interconnected large mesopores (∼20−50 nm) and large surface area facilitates a fast mediated electron transfer through electron mediators, while the decorated PANI on LMC surface enables the direct electron transfer via bacterial outer-membrane redox centers. Owing to the unique synergistic effect from both excellent electron transfer paths, the PANI-LMC hybrid anode harvests high power electricity with a maximum output power density of 1280 mW m −2 in Shewanella putrefaciens CN32 MFCs, 10-fold higher than that of conventional carbon cloth. The findings from this work suggest a new insight on design of high-efficient anode according to the multiple and flexible electrochemical process for practical MFC applications.

  16. Analytical solutions of the planar cyclic voltammetry process for two soluble species with equal diffusivities and fast electron transfer using the method of eigenfunction expansions

    Energy Technology Data Exchange (ETDEWEB)

    Samin, Adib; Lahti, Erik; Zhang, Jinsuo, E-mail: zhang.3558@osu.edu [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19" t" h Avenue, Columbus, Ohio 43210 (United States)

    2015-08-15

    Cyclic voltammetry is a powerful tool that is used for characterizing electrochemical processes. Models of cyclic voltammetry take into account the mass transport of species and the kinetics at the electrode surface. Analytical solutions of these models are not well-known due to the complexity of the boundary conditions. In this study we present closed form analytical solutions of the planar voltammetry model for two soluble species with fast electron transfer and equal diffusivities using the eigenfunction expansion method. Our solution methodology does not incorporate Laplace transforms and yields good agreement with the numerical solution. This solution method can be extended to cases that are more general and may be useful for benchmarking purposes.

  17. Analytical solutions of the planar cyclic voltammetry process for two soluble species with equal diffusivities and fast electron transfer using the method of eigenfunction expansions

    International Nuclear Information System (INIS)

    th Avenue, Columbus, Ohio 43210 (United States))" data-affiliation=" (Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Avenue, Columbus, Ohio 43210 (United States))" >Samin, Adib; th Avenue, Columbus, Ohio 43210 (United States))" data-affiliation=" (Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Avenue, Columbus, Ohio 43210 (United States))" >Lahti, Erik; th Avenue, Columbus, Ohio 43210 (United States))" data-affiliation=" (Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Avenue, Columbus, Ohio 43210 (United States))" >Zhang, Jinsuo

    2015-01-01

    Cyclic voltammetry is a powerful tool that is used for characterizing electrochemical processes. Models of cyclic voltammetry take into account the mass transport of species and the kinetics at the electrode surface. Analytical solutions of these models are not well-known due to the complexity of the boundary conditions. In this study we present closed form analytical solutions of the planar voltammetry model for two soluble species with fast electron transfer and equal diffusivities using the eigenfunction expansion method. Our solution methodology does not incorporate Laplace transforms and yields good agreement with the numerical solution. This solution method can be extended to cases that are more general and may be useful for benchmarking purposes

  18. Single-step electron transfer on the nanometer scale: ultra-fast charge shift in strongly coupled zinc porphyrin-gold porphyrin dyads.

    Science.gov (United States)

    Fortage, Jérôme; Boixel, Julien; Blart, Errol; Hammarström, Leif; Becker, Hans Christian; Odobel, Fabrice

    2008-01-01

    The synthesis, electrochemical properties, and photoinduced electron transfer processes of a series of three novel zinc(II)-gold(III) bisporphyrin dyads (ZnP--S--AuP(+)) are described. The systems studied consist of two trisaryl porphyrins connected directly in the meso position via an alkyne unit to tert-(phenylenethynylene) or penta(phenylenethynylene) spacers. In these dyads, the estimated center to center interporphyrin separation distance varies from 32 to 45 A. The absorption, emission, and electrochemical data indicate that there are strong electronic interactions between the linked elements, thanks to the direct attachment of the spacer on the porphyrin ring through the alkyne unit. At room temperature in toluene, light excitation of the zinc porphyrin results in almost quantitative formation of the charge shifted state (.+)ZnP--S--AuP(.), whose lifetime is in the order of hundreds of picoseconds. In this solvent, the charge-separated state decays to the ground state through the intermediate population of the zinc porphyrin triplet excited state. Excitation of the gold porphyrin leads instead to rapid energy transfer to the triplet ZnP. In dichloromethane the charge shift reactions are even faster, with time constants down to 2 ps, and may be induced also by excitation of the gold porphyrin. In this latter solvent, the longest charge-shifted lifetime (tau=2.3 ns) was obtained with the penta-(phenylenethynylene) spacer. The charge shift reactions are discussed in terms of bridge-mediated super-exchange mechanisms as electron or hole transfer. These new bis-porphyrin arrays, with strong electronic coupling, represent interesting molecular systems in which extremely fast and efficient long-range photoinduced charge shift occurs over a long distance. The rate constants are two to three orders of magnitude larger than for corresponding ZnP--AuP(+) dyads linked via meso-phenyl groups to oligo-phenyleneethynylene spacers. This study demonstrates the critical

  19. Advances in electron transfer chemistry

    CERN Document Server

    Mariano, Patrick S

    1993-01-01

    Advances in Electron Transfer Chemistry, Volume 3 presents studies that discuss findings in the various aspects of electron chemistry. The book is comprised of four chapters; each chapter reviews a work that tackles an issue in electron transfer chemistry. Chapter 1 discusses the photoinduced electron transfer in flexible biaryl donor-acceptor molecules. Chapter 2 tackles light-induced electron transfer in inorganic systems in homogeneous and heterogeneous phases. The book also covers internal geometry relaxation effects on electron transfer rates of amino-centered systems. The sequential elec

  20. Multiple-electron processes in fast ion-atom collisions

    International Nuclear Information System (INIS)

    Schlachter, A.S.

    1989-03-01

    Research in atomic physics at the Lawrence Berkeley Laboratory Super-HILAC and Bevalac accelerators on multiple-electron processes in fast ion-atom collisions is described. Experiments have studied various aspects of the charge-transfer, ionization, and excitation processes. Examples of processes in which electron correlation plays a role are resonant transfer and excitation and Auger-electron emission. Processes in which electron behavior can generally be described as uncorrelated include ionization and charge transfer in high-energy ion-atom collisions. A variety of experiments and results for energies from 1 MeV/u to 420 MeV/u are presented. 20 refs., 15 figs

  1. Fast electron transport in shaped solid targets

    International Nuclear Information System (INIS)

    Anle Lei; Cao, L.H.; He, X.T.; Zhang, W.Y.; Tanaka, K.A.; Kodama, R.; Mima, K.; Nakamura, T.; Normatsu, T.; Yu, W.

    2010-01-01

    Complete text of publication follows. The scheme of fast ignition fusion energy relies on the ultra-intense ultra-short (UIUS) laser energy transport into the compressed core plasma. One solution is to insert a hollow cone in the fuel shell to block the UIUS laser from the coronal plasma, thus allowing it to reach the core plasma. The cone not only can guide the UIUS laser to its tip, but can play important roles in the specific cone-in-shell target designed for FI. It was found in a PIC simulation that the cone can guide the fast electrons generated at the inner wall to propagate along the wall surface toward its tip, which would increase the energy density at the tip and might enhance the heating of the core plasma. Surface guiding of fast electrons with planar foil targets has been demonstrated experimentally. However, the guided fast electrons will mix the electrons generated ahead by the laser light with a planar target, and hence one cannot experimentally quantitatively validate the guide of the fast electrons. We investigate the cone guiding of fast electrons with an inverse cone target. We found a novel surface current of fast electrons propagating along the cone wall. The fast electrons generated at the planar outer tip of the inverse cone are guided and confined to propagate along the inverse cone wall to form a surface current by induced transient electric and magnetic fields associated with the current itself. Once departing from the source at the outer tip, this surface current of fast electrons is 'clean', neither experiencing the interacting laser light nor mixing fast electrons ahead, unlike those in cone or planar targets. This surface current in the inverse cone may explicitly give the capability of the guide of fast electron energy by the cone wall. The guiding and confinement of fast electrons is of important for fast ignition in inertial confinement fusion and several applications in high energy density science.

  2. Advances in electron transfer chemistry

    CERN Document Server

    Mariano, Patrick S

    1995-01-01

    Advances in Electron Transfer Chemistry, Volume 4 presents the reaction mechanisms involving the movement of single electrons. This book discusses the electron transfer reactions in organic, biochemical, organometallic, and excited state systems. Organized into four chapters, this volume begins with an overview of the photochemical behavior of two classes of sulfonium salt derivatives. This text then examines the parameters that control the efficiencies for radical ion pair formation. Other chapters consider the progress in the development of parameters that control the dynamics and reaction p

  3. Two-Electron Transfer Pathways.

    Science.gov (United States)

    Lin, Jiaxing; Balamurugan, D; Zhang, Peng; Skourtis, Spiros S; Beratan, David N

    2015-06-18

    The frontiers of electron-transfer chemistry demand that we develop theoretical frameworks to describe the delivery of multiple electrons, atoms, and ions in molecular systems. When electrons move over long distances through high barriers, where the probability for thermal population of oxidized or reduced bridge-localized states is very small, the electrons will tunnel from the donor (D) to acceptor (A), facilitated by bridge-mediated superexchange interactions. If the stable donor and acceptor redox states on D and A differ by two electrons, it is possible that the electrons will propagate coherently from D to A. While structure-function relations for single-electron superexchange in molecules are well established, strategies to manipulate the coherent flow of multiple electrons are largely unknown. In contrast to one-electron superexchange, two-electron superexchange involves both one- and two-electron virtual intermediate states, the number of virtual intermediates increases very rapidly with system size, and multiple classes of pathways interfere with one another. In the study described here, we developed simple superexchange models for two-electron transfer. We explored how the bridge structure and energetics influence multielectron superexchange, and we compared two-electron superexchange interactions to single-electron superexchange. Multielectron superexchange introduces interference between singly and doubly oxidized (or reduced) bridge virtual states, so that even simple linear donor-bridge-acceptor systems have pathway topologies that resemble those seen for one-electron superexchange through bridges with multiple parallel pathways. The simple model systems studied here exhibit a richness that is amenable to experimental exploration by manipulating the multiple pathways, pathway crosstalk, and changes in the number of donor and acceptor species. The features that emerge from these studies may assist in developing new strategies to deliver multiple

  4. Delta-electron emission in fast heavy ion atom collisions

    International Nuclear Information System (INIS)

    Schmidt-Boecking, H.; Ramm, U.; Berg, H.; Kelbch, C.; Feng Jiazhen; Hagmann, S.; Kraft, G.; Ullrich, J.

    1991-01-01

    The δ-electron emission processes occuring in fast heavy ion atom collisons are explained qualitatively. The different spectral structures of electron emission arising from either the target or the projectile are explained in terms of simple models of the kinetics of momentum transfer induced by the COULOMB forces. In collisions of very heavy ions with matter, high nuclear COULOMB forces are created. These forces lead to a strong polarization of the electronic states of the participated electrons. The effects of this polarization are discussed. (orig.)

  5. Slow and fast electron concentrations

    International Nuclear Information System (INIS)

    MacDougall, P.J.

    1991-01-01

    We consider the physical significance of the topology of the Laplacian of the electron momentum density. Via a single simple postulate, the electrical properties of metals, superconductors, and insulators are linked to well-defined and observable topological features in this distribution From this postulate it follows that a necessary condition for superconductivity is a closed path of cusp singularities in the material's time-averaged distribution. The topology of the path is constrained by the geometry of the sample and its environment. Yet, by virtue of the postulate, the unique collision properties of this path (in momentum space suggest that it charts a common course for electrons throughout the material, along which there is absolute minimum resistance to electron flow. As a further consequence of the postulate, it is also predicted that the preferred planes or axes of electron transport in anisotropic conductors with correspond to uniquely and unambiguously defined topological features of the Laplacian of the electron momentum distribution. (Author) 34 refs., 2 figs., tab

  6. Design of Measurement and Control System of Composite Fast Transfer Switch Based on PLC

    Directory of Open Access Journals (Sweden)

    ZHANG Hong-yi

    2017-06-01

    Full Text Available The fast transfer switch gets more extensive application in the power supply system along with the raising of power supply requirement for continuity and reliability in the sensitivity loads such as in airport,military place,hospital and large scale industrial production line. Therefore it is important that how to make fast transfer switch run safely and reliably. The paper expatiated the structure and principle of a fast transfer switch based on mechanical and electronic compound technology,and,according to the basic requirement and the characteristic of the fast transfer switch,a PLC mastered measuring and controlling system has been designed to raise the operation reliability of the fast transfer switch.

  7. 75 FR 9120 - Electronic Fund Transfers

    Science.gov (United States)

    2010-03-01

    ... FEDERAL RESERVE SYSTEM 12 CFR Part 205 [Regulation E; Docket No. R-1343] Electronic Fund Transfers... implements the Electronic Fund Transfer Act, and the official staff commentary to the regulation. The final..., the Board adopted a final rule under Regulation E, which implements the Electronic Fund Transfer Act...

  8. Intramolecular photoinduced electron-transfer in azobenzene-perylene diimide

    International Nuclear Information System (INIS)

    Feng Wen-Ke; Wang Shu-Feng; Gong Qi-Huang; Feng Yi-Yu; Feng Wei; Yi Wen-Hui

    2010-01-01

    This paper studies the intramolecular photoinduced electron-transfer (PET) of covalent bonded azobenzene-perylene diimide (AZO-PDI) in solvents by using steady-state and time-resolved fluorescence spectroscopy together with ultrafast transient absorption spectroscopic techniques. Fast fluorescence quenching is observed when AZO-PDI is excited at characteristic wavelengths of AZO and perylene moieties. Reductive electron-transfer with transfer rate faster than 10 11 s −1 is found. This PET process is also consolidated by femtosecond transient absorption spectra

  9. Exocellular electron transfer in anaerobic microbial communities

    NARCIS (Netherlands)

    Stams, A.J.M.; Bok, de F.A.M.; Plugge, C.M.; Eekert, van M.H.A.; Dolfing, J.; Schraa, G.

    2006-01-01

    Exocellular electron transfer plays an important role in anaerobic microbial communities that degrade organic matter. Interspecies hydrogen transfer between microorganisms is the driving force for complete biodegradation in methanogenic environments. Many organic compounds are degraded by obligatory

  10. Hierarchical control of electron-transfer

    DEFF Research Database (Denmark)

    Westerhoff, Hans V.; Jensen, Peter Ruhdal; Egger, Louis

    1997-01-01

    In this chapter the role of electron transfer in determining the behaviour of the ATP synthesising enzyme in E. coli is analysed. It is concluded that the latter enzyme lacks control because of special properties of the electron transfer components. These properties range from absence of a strong...... back pressure by the protonmotive force on the rate of electron transfer to hierarchical regulation of the expression of the gens that encode the electron transfer proteins as a response to changes in the bioenergetic properties of the cell.The discussion uses Hierarchical Control Analysis...

  11. Dielectric materials electrization by fast electrons

    International Nuclear Information System (INIS)

    Dyrkov, V.A.; Kononov, B.A.

    1990-01-01

    Electrization of short-circuited high-ohmage targets under irradiation by 50-200 keV electrons non-uniformly by volume is investigated both experimentally and theoretically. The obtained data show that effect of space charge field increases monotonically up to stationary state during irradiation. Time constant for space charge accumulation constitutes 1-10 min and has lower value for polymethylmethacrylate as compared with polyethyleneterephthalate and decreases with increase of beam current density. Good agreement of experimental and theoretical results for both materials confirms the validity of main positions of phonomenological model of space charge formation in dielectric materials under fast electron irradiation

  12. Electron transfer and energy transfer reactions in photoexcited a-nonathiophene/C60 films and solutions

    NARCIS (Netherlands)

    Janssen, R.A.J.; Moses, D.; Sariciftci, N.S.; Heeger, A.J.

    1994-01-01

    Photoexcitation of a nonathiophene in film or solution across the p-p* energy gap produces a metastable triplet state. In the presence of C60, on the other hand, an ultra fast electron transfer from the photoexcited nonathiophene onto C60 is observed in films, whereas in solution C60 is involved in

  13. Fast electrons in small solar flares

    International Nuclear Information System (INIS)

    Lin, R.P.

    1975-01-01

    Because approximately 5-100 keV electrons are frequently accelerated and emitted by the Sun in small flares, it is possible to define a detailed characteristic physical picture of these events. The review summarizes both the direct spacecraft observations of non-relativistic solar electrons, and observations of the X-ray and radio emission generated by these particles at the Sun and in the interplanetary medium. These observations bear on the basic astrophysical process of particle acceleration in tenuous plasmas. It is found that in many small solar flares the approximately 5-100 keV electrons accelerated during flash phase constitute the bulk of the total flare energy. Thus the basic flare mechanism in these flares essentially converts the available flare energy into fast electrons. These electrons may produce the other flare electromagnetic emissions through their interactions with the solar atmosphere. In large proton flares these electrons may provide the energy to eject material from the Sun and to create a shock wave which could then accelerate nuclei and electrons to much higher energies. (Auth.)

  14. Tunneling induced electron transfer between separated protons

    Science.gov (United States)

    Vindel-Zandbergen, Patricia; Meier, Christoph; Sola, Ignacio R.

    2018-04-01

    We study electron transfer between two separated protons using local control theory. In this symmetric system one can favour a slow transfer by biasing the algorithm, achieving high efficiencies for fixed nuclei. The solution can be parametrized using a sequence of a pump followed by a dump pulse that lead to tunneling-induced electron transfer. Finally, we study the effect of the nuclear kinetic energy on the efficiency. Even in the absence of relative motion between the protons, the spreading of the nuclear wave function is enough to reduce the yield of electronic transfer to less than one half.

  15. Exocellular electron transfer in anaerobic microbial communities.

    Science.gov (United States)

    Stams, Alfons J M; de Bok, Frank A M; Plugge, Caroline M; van Eekert, Miriam H A; Dolfing, Jan; Schraa, Gosse

    2006-03-01

    Exocellular electron transfer plays an important role in anaerobic microbial communities that degrade organic matter. Interspecies hydrogen transfer between microorganisms is the driving force for complete biodegradation in methanogenic environments. Many organic compounds are degraded by obligatory syntrophic consortia of proton-reducing acetogenic bacteria and hydrogen-consuming methanogenic archaea. Anaerobic microorganisms that use insoluble electron acceptors for growth, such as iron- and manganese-oxide as well as inert graphite electrodes in microbial fuel cells, also transfer electrons exocellularly. Soluble compounds, like humic substances, quinones, phenazines and riboflavin, can function as exocellular electron mediators enhancing this type of anaerobic respiration. However, direct electron transfer by cell-cell contact is important as well. This review addresses the mechanisms of exocellular electron transfer in anaerobic microbial communities. There are fundamental differences but also similarities between electron transfer to another microorganism or to an insoluble electron acceptor. The physical separation of the electron donor and electron acceptor metabolism allows energy conservation in compounds as methane and hydrogen or as electricity. Furthermore, this separation is essential in the donation or acceptance of electrons in some environmental technological processes, e.g. soil remediation, wastewater purification and corrosion.

  16. Seminar on Heat-transfer fluids for fast neutron reactors

    International Nuclear Information System (INIS)

    Brechet, Yves; Dautray, Robert; Friedel, Jacques; Brezin, Edouard; Martin, Georges; Pineau, Andre; Carre, Francois; Gauche, Francois; Rodriguez, Guillaume; Latge, Christian; Cabet, Celine; Garnier, Jean-Claude; Bamberger, Yves; Sauvage, Jean-Francois; Buisine, Denis; Agostini, Pietro; Ulyanov, Vladimir; Auger, Thierry; Heuer, Daniel; Ghetta, Veronique; Bubelis, Evaldas; Charlaix, Elisabeth; Barrat, Jean-Louis; Boquet, Lyderic; Glickman, Evgueny; Escaravage, Claude

    2014-03-01

    This book reports the content of a two-day meeting held by the Academy of Sciences on the use of heat-transfer fluids in fast neutron reactors. After a first part which proposes an overview of scientific and technical problems related to these heat-transfer fluids (heat transfer process, nuclear properties, chemistry, materials, risks), a contribution proposes a return on experience on the use of heat-transfer fluids in the different design options of reactors of fourth generation: from mercury to NaK in the first fast neutron reactor projects, specific assets and constraints of sodium used as heat-transfer fluid, concepts of fast neutron reactors cooled by something else than sodium, perspectives for projects and research in fast neutron reactors. The next contribution discusses the specifications of future fast-neutron reactors: expectations for fourth-generation reactors, expectations in terms of performance and of safety, specific challenges. The last contribution addresses actions to be undertaken in the field of research and development: actions regarding all reactor types or specific types as sodium-cooled reactors, lead cooled reactors, molten salt reactors, and gas-cooled fast reactors

  17. Transient Exciplex Formation Electron Transfer Mechanism

    OpenAIRE

    Michael G. Kuzmin; Irina V. Soboleva; Elena V. Dolotova

    2011-01-01

    Transient exciplex formation mechanism of excited-state electron transfer reactions is analyzed in terms of experimental data on thermodynamics and kinetics of exciplex formation and decay. Experimental profiles of free energy, enthalpy, and entropy for transient exciplex formation and decay are considered for several electron transfer reactions in various solvents. Strong electronic coupling in contact pairs of reactants causes substantial decrease of activation energy relative to that for c...

  18. Electron spectroscopy with fast heavy ions

    International Nuclear Information System (INIS)

    Schneider, D.

    1983-01-01

    Since about 1970 the spectroscopy of Auger-electrons and characteristic x-rays following energetic ion-atom collisions has received a great deal of attention. An increasing number of accelerators, capable of providing a large number of projectile ion species over a wide range of projectile energies, became available for studying ion-atom collision phenomena. Many charged particles from protons up to heavy ions like uranium can be accelerated to energies ranging over six orders of magnitude. This allows us to study systematically a great variety of effects accompanied by dynamic excitation processes of the atomic shells in either the projectile- or target-atoms. The studies yield fundamental information regarding the excitation mechanism (e.g., Coulomb and quasi-molecular excitation) and allow sensitive tests of atomic structure theories. This information in turn is valuable to other fields in physics like plasma-, astro-, or solid-state (surface) physics. It is a characteristic feature of fast heavy-ion accelerators that they can produce highly stripped ion species which have in turn the capability to highly ionize neutral target atoms or molecules in a single collision. The ionization process, mainly due to the strong electrical fields that are involved, allows us to study few-electron atoms with high atomic numbers Z. High resolution spectroscopy performed with these atoms allows a particularly good test of relativistic and QED effects. The probability of producing these few electron systems is determined by the charge state and the velocity of the projectile ions. In this contribution the possibilities of using electron spectroscopy as a tool to investigate fast ion-atom collisions is discussed and demonstrated with a few examples. 30 references

  19. Electron transfer by excited benzoquinone anions: slow rates for two-electron transitions.

    Science.gov (United States)

    Zamadar, Matibur; Cook, Andrew R; Lewandowska-Andralojc, Anna; Holroyd, Richard; Jiang, Yan; Bikalis, Jin; Miller, John R

    2013-09-05

    Electron transfer (ET) rate constants from the lowest excited state of the radical anion of benzoquinone, BQ(-•)*, were measured in THF solution. Rate constants for bimolecular electron transfer reactions typically reach the diffusion-controlled limit when the free-energy change, ΔG°, reaches -0.3 eV. The rate constants for ET from BQ(-•)* are one-to-two decades smaller at this energy and do not reach the diffusion-controlled limit until -ΔG° is 1.5-2.0 eV. The rates are so slow probably because a second electron must also undergo a transition to make use of the energy of the excited state. Similarly, ET, from solvated electrons to neutral BQ to form the lowest excited state, is slow, while fast ET is observed at a higher excited state, which can be populated in a transition involving only one electron. A simple picture based on perturbation theory can roughly account for the control of electron transfer by the need for transition of a second electron. The picture also explains how extra driving force (-ΔG°) can restore fast rates of electron transfer.

  20. Nuclear reorganization barriers to electron transfer

    International Nuclear Information System (INIS)

    Sutin, N.; Brunschwig, B.S.; Creutz, C.; Winkler, J.R.

    1988-01-01

    The nuclear barrier to electron transfer arises from the need for reorganization of intramolecular and solvent internuclear distances prior to electron transfer. For reactions with relatively small driving force (''normal'' free-energy region) the nuclear factors and rates increase as intrinsic inner-shell and outer-shell barriers decrease; this is illustrated by data for transition metal complexes in their ground electronic states. By contrast, in the inverted free-energy region, rates and nuclear factors decrease with decreasing ''intrinsic'' barriers; this is illustrated by data for the decay of charge-transfer excited states. Several approaches to the evaluation of the outer-shell barrier are explored in an investigation of the distance dependence of the nuclear factor in intramolecular electron-transfer processes. 39 refs., 14 figs., 3 tabs

  1. Advances in electron transfer chemistry, v.6

    CERN Document Server

    Mariano, PS

    1999-01-01

    It is clear that electron transfer chemisty is now one of the most active areas of chemical study. Advances in Electron Transfer Chemistry has been designed to allow scientists who are developing new knowledge in this rapidly expanding area to describe their most recent research findings. This volume will serve those interested in learning about current breakthroughs in this rapidly expanding area of chemical research.

  2. Linear circuit transfer functions an introduction to fast analytical techniques

    CERN Document Server

    Basso, Christophe P

    2016-01-01

    Linear Circuit Transfer Functions: An introduction to Fast Analytical Techniques teaches readers how to determine transfer functions of linear passive and active circuits by applying Fast Analytical Circuits Techniques. Building on their existing knowledge of classical loop/nodal analysis, the book improves and expands their skills to unveil transfer functions in a swift and efficient manner. Starting with simple examples, the author explains step-by-step how expressing circuits time constants in different configurations leads to writing transfer functions in a compact and insightful way. By learning how to organize numerators and denominators in the fastest possible way, readers will speed-up analysis and predict the frequency resp nse of simple to complex circuits. In some cases, they will be able to derive the final expression by inspection, without writing a line of algebra. Key features: * Emphasizes analysis through employing time constant-based methods discussed in other text books but not widely us...

  3. Single-Molecule Interfacial Electron Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Lu, H. Peter [Bowling Green State Univ., Bowling Green, OH (United States). Dept. of Chemistry and Center for Photochemical Sciences

    2017-11-28

    This project is focused on the use of single-molecule high spatial and temporal resolved techniques to study molecular dynamics in condensed phase and at interfaces, especially, the complex reaction dynamics associated with electron and energy transfer rate processes. The complexity and inhomogeneity of the interfacial ET dynamics often present a major challenge for a molecular level comprehension of the intrinsically complex systems, which calls for both higher spatial and temporal resolutions at ultimate single-molecule and single-particle sensitivities. Combined single-molecule spectroscopy and electrochemical atomic force microscopy approaches are unique for heterogeneous and complex interfacial electron transfer systems because the static and dynamic inhomogeneities can be identified and characterized by studying one molecule at a specific nanoscale surface site at a time. The goal of our project is to integrate and apply these spectroscopic imaging and topographic scanning techniques to measure the energy flow and electron flow between molecules and substrate surfaces as a function of surface site geometry and molecular structure. We have been primarily focusing on studying interfacial electron transfer under ambient condition and electrolyte solution involving both single crystal and colloidal TiO2 and related substrates. The resulting molecular level understanding of the fundamental interfacial electron transfer processes will be important for developing efficient light harvesting systems and broadly applicable to problems in fundamental chemistry and physics. We have made significant advancement on deciphering the underlying mechanism of the complex and inhomogeneous interfacial electron transfer dynamics in dyesensitized TiO2 nanoparticle systems that strongly involves with and regulated by molecule-surface interactions. We have studied interfacial electron transfer on TiO2 nanoparticle surfaces by using ultrafast single

  4. Transient Exciplex Formation Electron Transfer Mechanism

    Directory of Open Access Journals (Sweden)

    Michael G. Kuzmin

    2011-01-01

    Full Text Available Transient exciplex formation mechanism of excited-state electron transfer reactions is analyzed in terms of experimental data on thermodynamics and kinetics of exciplex formation and decay. Experimental profiles of free energy, enthalpy, and entropy for transient exciplex formation and decay are considered for several electron transfer reactions in various solvents. Strong electronic coupling in contact pairs of reactants causes substantial decrease of activation energy relative to that for conventional long-range ET mechanism, especially for endergonic reactions, and provides the possibility for medium reorganization concatenated to gradual charge shift in contrast to conventional preliminary medium and reactants reorganization. Experimental criteria for transient exciplex formation (concatenated mechanism of excited-state electron transfer are considered. Available experimental data show that this mechanism dominates for endergonic ET reactions and provides a natural explanation for a lot of known paradoxes of ET reactions.

  5. Single Molecule Spectroscopy of Electron Transfer

    International Nuclear Information System (INIS)

    Holman, Michael; Zang, Ling; Liu, Ruchuan; Adams, David M.

    2009-01-01

    The objectives of this research are threefold: (1) to develop methods for the study electron transfer processes at the single molecule level, (2) to develop a series of modifiable and structurally well defined molecular and nanoparticle systems suitable for detailed single molecule/particle and bulk spectroscopic investigation, (3) to relate experiment to theory in order to elucidate the dependence of electron transfer processes on molecular and electronic structure, coupling and reorganization energies. We have begun the systematic development of single molecule spectroscopy (SMS) of electron transfer and summaries of recent studies are shown. There is a tremendous need for experiments designed to probe the discrete electronic and molecular dynamic fluctuations of single molecules near electrodes and at nanoparticle surfaces. Single molecule spectroscopy (SMS) has emerged as a powerful method to measure properties of individual molecules which would normally be obscured in ensemble-averaged measurement. Fluctuations in the fluorescence time trajectories contain detailed molecular level statistical and dynamical information of the system. The full distribution of a molecular property is revealed in the stochastic fluctuations, giving information about the range of possible behaviors that lead to the ensemble average. In the case of electron transfer, this level of understanding is particularly important to the field of molecular and nanoscale electronics: from a device-design standpoint, understanding and controlling this picture of the overall range of possible behaviors will likely prove to be as important as designing ia the ideal behavior of any given molecule.

  6. Legal Risk Associated with Electronic Funds Transfer

    OpenAIRE

    Abdulah, Samahir

    2014-01-01

    The past thirty years have seen rapid advances in the technological component of banking services and as a consequence new legal issues have come to the fore, especially with regard to Electronic Fund Transfers (EFTs) which are now used to transfer money around the world, and have made fund transactions between payers and payees easier, faster and more secure. The method involves risks for both banks and customers, due to the possibility of unauthorized payments risks, credit and insolvency p...

  7. Facile Interfacial Electron Transfer of Hemoglobin

    Directory of Open Access Journals (Sweden)

    Chunhai Fan

    2005-12-01

    Full Text Available Abstract: We herein describe a method of depositing hemoglobin (Hb and sulfonated polyaniline (SPAN on GC electrodes that facilitate interfacial protein electron transfer. Well-defined, reproducible, chemically reversible peaks of Hb and SPAN can be obtained in our experiments. We also observed enhanced peroxidase activity of Hb in SPAN films. These results clearly showed that SPAN worked as molecular wires and effectively exchanged electrons between Hb and electrodes.Mediated by Conjugated Polymers

  8. Fast and efficient wireless power transfer via transitionless quantum driving.

    Science.gov (United States)

    Paul, Koushik; Sarma, Amarendra K

    2018-03-07

    Shortcut to adiabaticity (STA) techniques have the potential to drive a system beyond the adiabatic limits. Here, we present a robust and efficient method for wireless power transfer (WPT) between two coils based on the so-called transitionless quantum driving (TQD) algorithm. We show that it is possible to transfer power between the coils significantly fast compared to its adiabatic counterpart. The scheme is fairly robust against the variations in the coupling strength and the coupling distance between the coils. Also, the scheme is found to be reasonably immune to intrinsic losses in the coils.

  9. Fast electron microscopy via compressive sensing

    Science.gov (United States)

    Larson, Kurt W; Anderson, Hyrum S; Wheeler, Jason W

    2014-12-09

    Various technologies described herein pertain to compressive sensing electron microscopy. A compressive sensing electron microscope includes a multi-beam generator and a detector. The multi-beam generator emits a sequence of electron patterns over time. Each of the electron patterns can include a plurality of electron beams, where the plurality of electron beams is configured to impart a spatially varying electron density on a sample. Further, the spatially varying electron density varies between each of the electron patterns in the sequence. Moreover, the detector collects signals respectively corresponding to interactions between the sample and each of the electron patterns in the sequence.

  10. Electron Cyclotron Maser Emissions from Evolving Fast Electron Beams

    Science.gov (United States)

    Tang, J. F.; Wu, D. J.; Chen, L.; Zhao, G. Q.; Tan, C. M.

    2016-05-01

    Fast electron beams (FEBs) are common products of solar active phenomena. Solar radio bursts are an important diagnostic tool for understanding FEBs and the solar plasma environment in which they propagate along solar magnetic fields. In particular, the evolution of the energy spectrum and velocity distribution of FEBs due to the interaction with the ambient plasma and field during propagation can significantly influence the efficiency and properties of their emissions. In this paper, we discuss the possible evolution of the energy spectrum and velocity distribution of FEBs due to energy loss processes and the pitch-angle effect caused by magnetic field inhomogeneity, and we analyze the effects of the evolution on electron-cyclotron maser (ECM) emission, which is one of the most important mechanisms for producing solar radio bursts by FEBs. Our results show that the growth rates all decrease with the energy loss factor Q, but increase with the magnetic mirror ratio σ as well as with the steepness index δ. Moreover, the evolution of FEBs can also significantly influence the fastest growing mode and the fastest growing phase angle. This leads to the change of the polarization sense of the ECM emission. In particular, our results also reveal that an FEB that undergoes different evolution processes will generate different types of ECM emission. We believe the present results to be very helpful for a more comprehensive understanding of the dynamic spectra of solar radio bursts.

  11. ELECTRON CYCLOTRON MASER EMISSIONS FROM EVOLVING FAST ELECTRON BEAMS

    International Nuclear Information System (INIS)

    Tang, J. F.; Wu, D. J.; Chen, L.; Zhao, G. Q.; Tan, C. M.

    2016-01-01

    Fast electron beams (FEBs) are common products of solar active phenomena. Solar radio bursts are an important diagnostic tool for understanding FEBs and the solar plasma environment in which they propagate along solar magnetic fields. In particular, the evolution of the energy spectrum and velocity distribution of FEBs due to the interaction with the ambient plasma and field during propagation can significantly influence the efficiency and properties of their emissions. In this paper, we discuss the possible evolution of the energy spectrum and velocity distribution of FEBs due to energy loss processes and the pitch-angle effect caused by magnetic field inhomogeneity, and we analyze the effects of the evolution on electron-cyclotron maser (ECM) emission, which is one of the most important mechanisms for producing solar radio bursts by FEBs. Our results show that the growth rates all decrease with the energy loss factor Q , but increase with the magnetic mirror ratio σ as well as with the steepness index δ . Moreover, the evolution of FEBs can also significantly influence the fastest growing mode and the fastest growing phase angle. This leads to the change of the polarization sense of the ECM emission. In particular, our results also reveal that an FEB that undergoes different evolution processes will generate different types of ECM emission. We believe the present results to be very helpful for a more comprehensive understanding of the dynamic spectra of solar radio bursts.

  12. Elastic electron scattering at large momentum transfer

    International Nuclear Information System (INIS)

    Arnold, R.G.

    1979-05-01

    A review is given of elastic electron scattering at large momentum transfer (Q 2 > 20 fm -2 ) from nuclei with A less than or equal to 4. Recent experimental results are reviewed and the current problems in interpretation of these results are pointed out. Some questions for future experiments are posed, and a preview of possible future measurements is presented. 28 references

  13. Promoting interspecies electron transfer with biochar

    DEFF Research Database (Denmark)

    Chen, Shanshan; Rotaru, Amelia-Elena; Shrestha, Pravin Malla

    2014-01-01

    Biochar, a charcoal-like product of the incomplete combustion of organic materials, is an increasingly popular soil amendment designed to improve soil fertility. We investigated the possibility that biochar could promote direct interspecies electron transfer (DIET) in a manner similar...... biochar may enhance methane production from organic wastes under anaerobic conditions....

  14. Quantum effects in biological electron transfer

    Czech Academy of Sciences Publication Activity Database

    de la Lande, A.; Babcock, N. S.; Řezáč, Jan; Levy, B.; Sanders, B. C.; Salahub, D.

    2012-01-01

    Roč. 14, č. 17 (2012), s. 5902-5918 ISSN 1463-9076 Institutional research plan: CEZ:AV0Z40550506 Keywords : electron transfer * tunnelling * decoherence * semi-classical molecular dynamics * density functional theory Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.829, year: 2012

  15. Defining Electron Bifurcation in the Electron-Transferring Flavoprotein Family.

    Science.gov (United States)

    Garcia Costas, Amaya M; Poudel, Saroj; Miller, Anne-Frances; Schut, Gerrit J; Ledbetter, Rhesa N; Fixen, Kathryn R; Seefeldt, Lance C; Adams, Michael W W; Harwood, Caroline S; Boyd, Eric S; Peters, John W

    2017-11-01

    Electron bifurcation is the coupling of exergonic and endergonic redox reactions to simultaneously generate (or utilize) low- and high-potential electrons. It is the third recognized form of energy conservation in biology and was recently described for select electron-transferring flavoproteins (Etfs). Etfs are flavin-containing heterodimers best known for donating electrons derived from fatty acid and amino acid oxidation to an electron transfer respiratory chain via Etf-quinone oxidoreductase. Canonical examples contain a flavin adenine dinucleotide (FAD) that is involved in electron transfer, as well as a non-redox-active AMP. However, Etfs demonstrated to bifurcate electrons contain a second FAD in place of the AMP. To expand our understanding of the functional variety and metabolic significance of Etfs and to identify amino acid sequence motifs that potentially enable electron bifurcation, we compiled 1,314 Etf protein sequences from genome sequence databases and subjected them to informatic and structural analyses. Etfs were identified in diverse archaea and bacteria, and they clustered into five distinct well-supported groups, based on their amino acid sequences. Gene neighborhood analyses indicated that these Etf group designations largely correspond to putative differences in functionality. Etfs with the demonstrated ability to bifurcate were found to form one group, suggesting that distinct conserved amino acid sequence motifs enable this capability. Indeed, structural modeling and sequence alignments revealed that identifying residues occur in the NADH- and FAD-binding regions of bifurcating Etfs. Collectively, a new classification scheme for Etf proteins that delineates putative bifurcating versus nonbifurcating members is presented and suggests that Etf-mediated bifurcation is associated with surprisingly diverse enzymes. IMPORTANCE Electron bifurcation has recently been recognized as an electron transfer mechanism used by microorganisms to maximize

  16. Effects of electrostatic interactions on electron transfer reactions

    International Nuclear Information System (INIS)

    Hickel, B.

    1987-01-01

    The fast reactions of electron transfer are studied by pulse radiolysis. This technique allows the creation in about 10 -8 second radicals and radical ions with high redox potentials. For solvated electrons electrostatic interaction on the kinetics of reactions limited by diffusion is described by Debye's equation when ion mobility is known. Deviation from theory can occur in ion pairs formation. This is evidenced experimentally for anions by cation complexation with a cryptate. Relatively slow reactions are more sensitive to electrostatic interactions than limited by diffusion. If ion pairs are not formed kinetics constant depends on dielectric constant of solvent and reaction radius. Experimentally is studied the effect of electrostatic interaction on the rate constants of solvated electrons with anions and cations in water-ethanol mixtures where the dielectric constant change from 80 to 25 at room temperature. 17 refs

  17. The Booster to AGS beam transfer fast kicker systems

    International Nuclear Information System (INIS)

    Zhang, W.; Bunicci, J.; Soukas, A.V.; Zhang, S.Y.

    1992-01-01

    The Brookhaven AGS Booster has a very successful commissioning period in June 1991. The third phase of that commissioning was a beam extraction test. The Booster extraction fast kicker (F3) deflected a 1.2 GeV proton beam from the Booster circulating orbit into the extraction septum aperture, partially down the extraction line to a temporary beam stop. Now, the Booster is committed to the AGS operations program for both heavy ion and proton beams. Thus, the Booster extraction and the corresponding AGS injection systems must operate routinely up to a pulse repetition frequency of 7.5 Hertz, and up to a beam energy of 1.5 Gev. The injection fast kicker is located in the A5 section of the AGS ring and is used to deflect the proton or heavy ion beam into its final AGS closed orbit. A distinctive feature of the AGS injection fast kicker modulators is the tail-bitting function required for proton beam injection. This enables the system to produce a fast current fall time to go along with the high current pulse amplitude with a fast rise time. The AGS injection fast kicker system has three pulse modulators, and each modulator consists of two thyratrons. The main PFN thyratrons switch on the current, and the tail bitting thyratrons are used to force the magnet current to decrease rapidly. Two digital pulse delay generators are used to align the main thyratrons and the tail bitting thyratrons respectively. The system has been tested and installed. The final commissioning of the Booster to AGS beam transfer line and injection is currently being undertaken. In this article, the system design, realization techniques and performance data will be presented

  18. Biotechnological Aspects of Microbial Extracellular Electron Transfer

    Science.gov (United States)

    Kato, Souichiro

    2015-01-01

    Extracellular electron transfer (EET) is a type of microbial respiration that enables electron transfer between microbial cells and extracellular solid materials, including naturally-occurring metal compounds and artificial electrodes. Microorganisms harboring EET abilities have received considerable attention for their various biotechnological applications, in addition to their contribution to global energy and material cycles. In this review, current knowledge on microbial EET and its application to diverse biotechnologies, including the bioremediation of toxic metals, recovery of useful metals, biocorrosion, and microbial electrochemical systems (microbial fuel cells and microbial electrosynthesis), were introduced. Two potential biotechnologies based on microbial EET, namely the electrochemical control of microbial metabolism and electrochemical stimulation of microbial symbiotic reactions (electric syntrophy), were also discussed. PMID:26004795

  19. Dynamics in electron transfer protein complexes

    OpenAIRE

    Bashir, Qamar

    2010-01-01

    Recent studies have provided experimental evidence for the existence of an encounter complex, a transient intermediate in the formation of protein complexes. We have used paramagnetic relaxation enhancement NMR spectroscopy in combination with Monte Carlo simulations to characterize and visualize the ensemble of encounter orientations in the short-lived electron transfer complex of yeast Cc and CcP. The complete conformational space sampled by the protein molecules during the dynamic part of ...

  20. Electron transfer from electronic excited states to sub-vacuum electron traps in amorphous ice

    International Nuclear Information System (INIS)

    Vichnevetski, E.; Bass, A.D.; Sanche, L.

    2000-01-01

    We investigate the electron stimulated yield of electronically excited argon atoms (Ar * ) from monolayer quantities of Ar deposited onto thin films of amorphous ice. Two peaks of narrow width ( - electron-exciton complex into exciton states, by the transfer of an electron into a sub-vacuum electron state within the ice film. However, the 10.7 eV feature is shifted to lower energy since electron attachment to Ar occurs within small pores of amorphous ice. In this case, the excess electron is transferred into an electron trap below the conduction band of the ice layer

  1. Transfer coating by electron initiated polymerization

    International Nuclear Information System (INIS)

    Nablo, S.V.

    1984-01-01

    The high speed and depth of cure possible with electron initiated monomer/oligomer coating systems provide many new opportunities for approaches to product finishing. Moreover, the use of transfer or cast coating using films or metallic surfaces offers the ability to precisely control the surface topology of liquid film surfaces during polymerization. Transfer coating such as with textiles has been a commercial process for many years and the synergistic addition of EB technology permits the manufacture of unusual new products. One of these, the casting paper used in the manufacture of vinyl and urethane fabrics, is the first EB application to use a drum surface for pattern replication in the coating. In this case the coated paper is cured against, and then released from, an engraved drum surface. Recent developments in the use of plastic films for transfer have been applied to the manufacture of transfer metallized and coated paper and paperboard products for packaging. Details of these and related processes are presented as well as a discussion of the typical product areas (e.g. photographic papers, release papers, magnetic media) using this high speed transfer technology

  2. Transfer coating by electron initiated polymerization

    International Nuclear Information System (INIS)

    Nablo, S.V.

    1985-01-01

    The high speed and depth of cure possible with electron initiated monomer/oligomer coating systems provide many new opportunities for approaches to product finishing. Moreover, the use of transfer or cast coating using films or metallic surfaces offers the ability to precisely control the surface topology of liquid film surfaces during polymerization. Transfer coating such as with textiles has been a commercial process for many years and the synergistic addition of EB technology permits the manufacture of unusual new products. One of these, the casting paper used in the manufacture of vinyl and urethane fabrics, is the first EB application to use a drum surface for pattern replication in the coating. In this case the coated paper is cured against, and then released from, an engraved drum surface. Recent developments in the use of plastic films for transfer have been applied to the manufacture of transfer metallized and coated paper and paperboard products for packaging. Details of these and related processes will be presented as well as a discussion of the typical product areas using this high speed transfer technology. (author)

  3. Promoting Interspecies Electron Transfer with Biochar

    Science.gov (United States)

    Chen, Shanshan; Rotaru, Amelia-Elena; Shrestha, Pravin Malla; Malvankar, Nikhil S.; Liu, Fanghua; Fan, Wei; Nevin, Kelly P.; Lovley, Derek R.

    2014-01-01

    Biochar, a charcoal-like product of the incomplete combustion of organic materials, is an increasingly popular soil amendment designed to improve soil fertility. We investigated the possibility that biochar could promote direct interspecies electron transfer (DIET) in a manner similar to that previously reported for granular activated carbon (GAC). Although the biochars investigated were 1000 times less conductive than GAC, they stimulated DIET in co-cultures of Geobacter metallireducens with Geobacter sulfurreducens or Methanosarcina barkeri in which ethanol was the electron donor. Cells were attached to the biochar, yet not in close contact, suggesting that electrons were likely conducted through the biochar, rather than biological electrical connections. The finding that biochar can stimulate DIET may be an important consideration when amending soils with biochar and can help explain why biochar may enhance methane production from organic wastes under anaerobic conditions. PMID:24846283

  4. Inelastic scattering of fast electrons by crystals

    International Nuclear Information System (INIS)

    Allen, L.J.; Josefsson, T.W.

    1995-01-01

    Generalized fundamental equations for electron diffraction in crystals, which include the effect of inelastic scattering described by a nonlocal interaction, are derived. An expression is obtained for the cross section for any specific type of inelastic scattering (e.g. inner-shell ionization, Rutherford backscattering). This result takes into account all other (background) inelastic scattering in the crystal leading to absorption from the dynamical Bragg-reflected beams, in practice mainly due to thermal diffuse scattering. There is a contribution to the cross section from all absorbed electrons, which form a diffuse background, as well as from the dynamical electrons. The approximations involved, assuming that the interactions leading to inelastic scattering can be described by a local potential are discussed, together with the corresponding expression for the cross section. It is demonstrated by means of an example for K-shell electron energy loss spectroscopy that nonlocal effects can be significant. 47 refs., 4 figs

  5. 14 CFR 1260.69 - Electronic funds transfer payment methods.

    Science.gov (United States)

    2010-01-01

    ... Government by electronic funds transfer through the Treasury Fedline Payment System (FEDLINE) or the... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Electronic funds transfer payment methods... COOPERATIVE AGREEMENTS General Special Conditions § 1260.69 Electronic funds transfer payment methods...

  6. Effect of electrostatic interactions on electron-transfer reactions

    International Nuclear Information System (INIS)

    Hickel, B.

    1987-01-01

    Fast reactions of electron transfer are studied by pulsed radiolysis. By this technique radicals and ionic radicals with high redox potentials are created homogeneously in the solution in about 10 -8 second. For solvated electron effect of electrostatic interaction on kinetics of reactions limited by diffusion is obtained with a good approximation by the Debye equation when ion mobility is known. Deviation from the theory occurs in ion pair formation, which is evidenced experimentally in reactions between anions when cations are complexed by a cryptate. Slow reactions k 8 M -1 s -1 are more sensitive to electrostatic interactions than reactions limited by diffusion. When there is no ion pair formation the velocity constant depends upon dielectric constant of the solvent and reaction distance. 17 refs

  7. A fast infrared radiative transfer model for overlapping clouds

    International Nuclear Information System (INIS)

    Niu Jianguo; Yang Ping; Huang Hunglung; Davies, James E.; Li Jun; Baum, Bryan A.; Hu, Yong X.

    2007-01-01

    A fast infrared radiative transfer model (FIRTM2) appropriate for application to both single-layered and overlapping cloud situations is developed for simulating the outgoing infrared spectral radiance at the top of the atmosphere (TOA). In FIRTM2 a pre-computed library of cloud reflectance and transmittance values is employed to account for one or two cloud layers, whereas the background atmospheric optical thickness due to gaseous absorption can be computed from a clear-sky radiative transfer model. FIRTM2 is applicable to three atmospheric conditions: (1) clear-sky (2) single-layered ice or water cloud, and (3) two simultaneous cloud layers in a column (e.g., ice cloud overlying water cloud). Moreover, FIRTM2 outputs the derivatives (i.e., Jacobians) of the TOA brightness temperature with respect to cloud optical thickness and effective particle size. Sensitivity analyses have been carried out to assess the performance of FIRTM2 for two spectral regions, namely the longwave (LW) band (587.3-1179.5 cm -1 ) and the short-to-medium wave (SMW) band (1180.1-2228.9 cm -1 ). The assessment is carried out in terms of brightness temperature differences (BTD) between FIRTM2 and the well-known discrete ordinates radiative transfer model (DISORT), henceforth referred to as BTD (F-D). The BTD (F-D) values for single-layered clouds are generally less than 0.8 K. For the case of two cloud layers (specifically ice cloud over water cloud), the BTD (F-D) values are also generally less than 0.8 K except for the SMW band for the case of a very high altitude (>15 km) cloud comprised of small ice particles. Note that for clear-sky atmospheres, FIRTM2 reduces to the clear-sky radiative transfer model that is incorporated into FIRTM2, and the errors in this case are essentially those of the clear-sky radiative transfer model

  8. Fast pulse beam generation systems for electron accelerators

    International Nuclear Information System (INIS)

    Koontz, R.F.

    1977-01-01

    The fast pulse beam generation system to supply the SLAC storage ring, SPEAR, by the two one nanosecond bunch electron beam pulses is described. Generation of these pulses is accomplished with a combination of a fast pulsed grided gun and a synchronized transverse beam chopper. Fast gun based on spherical cathode-grid assembly has output current up to 2As. Fast pulse amplifier system can handle trains of short pulses with repetition rates up to 40 MHz during the 1.6 μs normal accelerating time. Chopping deflector system consists of a resonant coaxial line with the deflecting plates. The resonator frequency is 39.667 MHz. A schematic diagram of the resonant system is shown. The fast beam pickup system has a one hundred picosecond rise time overrall. Fast beam generation and chopper systems permit to generate almost any short or single bunch beam profile needed for experiments

  9. Fast wire scanner for intense electron beams

    Directory of Open Access Journals (Sweden)

    T. Moore

    2014-02-01

    Full Text Available We have developed a cost-effective, fast rotating wire scanner for use in accelerators where high beam currents would otherwise melt even carbon wires. This new design uses a simple planetary gear setup to rotate a carbon wire, fixed at one end, through the beam at speeds in excess of 20  m/s. We present results from bench tests, as well as transverse beam profile measurements taken at Cornell’s high-brightness energy recovery linac photoinjector, for beam currents up to 35 mA.

  10. Single-Molecule Interfacial Electron Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Wilson [Univ. of California, Irvine, CA (United States)

    2018-02-03

    Interfacial electron transfer (ET) plays an important role in many chemical and biological processes. Specifically, interfacial ET in TiO2-based systems is important to solar energy technology, catalysis, and environmental remediation technology. However, the microscopic mechanism of interfacial ET is not well understood with regard to atomic surface structure, molecular structure, bonding, orientation, and motion. In this project, we used two complementary methodologies; single-molecule fluorescence spectroscopy, and scanning-tunneling microscopy and spectroscopy (STM and STS) to address this scientific need. The goal of this project was to integrate these techniques and measure the molecular dependence of ET between adsorbed molecules and TiO2 semiconductor surfaces and the ET induced reactions such as the splitting of water. The scanning probe techniques, STM and STS, are capable of providing the highest spatial resolution but not easily time-resolved data. Single-molecule fluorescence spectroscopy is capable of good time resolution but requires further development to match the spatial resolution of the STM. The integrated approach involving Peter Lu at Bowling Green State University (BGSU) and Wilson Ho at the University of California, Irvine (UC Irvine) produced methods for time and spatially resolved chemical imaging of interfacial electron transfer dynamics and photocatalytic reactions. An integral aspect of the joint research was a significant exchange of graduate students to work at the two institutions. This project bridged complementary approaches to investigate a set of common problems by working with the same molecules on a variety of solid surfaces, but using appropriate techniques to probe under ambient (BGSU) and ultrahigh vacuum (UCI) conditions. The molecular level understanding of the fundamental interfacial electron transfer processes obtained in this joint project will be important for developing efficient light harvesting

  11. Double electron transfer in H- + H+ collisions

    International Nuclear Information System (INIS)

    Braeuning, H; Helm, H; Briggs, J S; Salzborn, E

    2007-01-01

    Absolute cross sections for double electron transfer in H - + H + collisions have been measured for center-of-mass energies from 0.5 keV to 12 keV. Clear oscillations in the cross section are observed which are in excellent agreement with earlier measurements at lower energies by Brouillard et al (1979) as well as Peart and Dolder (1979). After an oscillation maximum at 3 keV center-of-mass energy the cross section decreases for increasing energy with no indication of further oscillations

  12. Characterization of LH induced current carrying fast electrons in JET

    Energy Technology Data Exchange (ETDEWEB)

    Ramponi, G.; Airoldi, A. [Consiglio Nazionale delle Ricerche, Milan (Italy). Lab. di Fisica del Plasma; Bartlett, D.; Brusati, M.; Froissard, P.; Gormezano, C.; Rimini, F.; Silva, R.P. da; Tanzi, C.P. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1992-12-31

    Lower Hybrid Current Drive (LHCD) experiments have recently been made at JET by coupling up to 2.4 MW of RF power at 3.7 GHz, with a power spectrum centered at n{sub ||} = 1.8 {+-} 0.2 corresponding to a resonating electron energy of about 100 keV via Electron Landau Damping. The Current Drive (CD) efficiency has been observed to increase when LH and ICRH power are applied simultaneously to the plasma, suggesting that a part of the fast magnetosonic wave is absorbed on the LH-generated fast electrons. An important problem of CD experiments in tokamaks is the determination of the radial distribution of the driven current and the characterization in the momentum space of the current carrying fast electrons by using appropriate diagnostic tools. For this purpose, a combined analysis of the Electron Cyclotron Emission (ECE) and of the Fast Electron Bremsstrahlung (FEB) measurements has been made, allowing the relevant parameters of the suprathermal electrons to be estimated. (author) 5 refs., 5 figs., 2 tabs.

  13. Characterization of LH induced current carrying fast electrons in JET

    International Nuclear Information System (INIS)

    Ramponi, G.; Airoldi, A.; Bartlett, D.; Brusati, M.; Froissard, P.; Gormezano, C.; Rimini, F.; Silva, R.P. da; Tanzi, C.P.

    1992-01-01

    Lower Hybrid Current Drive (LHCD) experiments have recently been made at JET by coupling up to 2.4 MW of RF power at 3.7 GHz, with a power spectrum centered at n || = 1.8 ± 0.2 corresponding to a resonating electron energy of about 100 keV via Electron Landau Damping. The Current Drive (CD) efficiency has been observed to increase when LH and ICRH power are applied simultaneously to the plasma, suggesting that a part of the fast magnetosonic wave is absorbed on the LH-generated fast electrons. An important problem of CD experiments in tokamaks is the determination of the radial distribution of the driven current and the characterization in the momentum space of the current carrying fast electrons by using appropriate diagnostic tools. For this purpose, a combined analysis of the Electron Cyclotron Emission (ECE) and of the Fast Electron Bremsstrahlung (FEB) measurements has been made, allowing the relevant parameters of the suprathermal electrons to be estimated. (author) 5 refs., 5 figs., 2 tabs

  14. Electron transfer pathways in microbial oxygen biocathodes

    Energy Technology Data Exchange (ETDEWEB)

    Freguia, Stefano, E-mail: stefano@kais.kyoto-u.ac.j [Bio-analytical and Physical Chemistry Laboratory, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8205 (Japan); Tsujimura, Seiya, E-mail: seiya@kais.kyoto-u.ac.j [Bio-analytical and Physical Chemistry Laboratory, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8205 (Japan); Kano, Kenji, E-mail: kkano@kais.kyoto-u.ac.j [Bio-analytical and Physical Chemistry Laboratory, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8205 (Japan)

    2010-01-01

    The ability of some bacteria to enhance the rate of cathodic oxygen reduction to water has been recently discovered, opening the way to an entirely renewable and environmentally friendly concept of biocathode. In this study we reveal that several mechanisms may induce catalytic effects by bacteria. These comprise mechanisms that are putatively beneficial to the bacteria as well as mechanisms which are merely side effects, including quinone autoxidation and direct O{sub 2} reduction by heme compounds. Here we showed that 1 muM of ACNQ is able to generate a significant catalytic wave for oxygen reduction, with onset at approximately 0 V vs. SHE. Similarly, adsorption of hemin on a carbon surface catalyses O{sub 2} reduction to H{sub 2}O{sub 2} with an onset of +0.2 V vs. SHE. To evaluate the catalytic pathways of live cells on cathodic oxygen reduction, two species of electrochemically active bacteria were selected as pure cultures, namely Acinetobacter calcoaceticus and Shewanella putrefaciens. The former appears to exploit a self-excreted redox compound with redox characteristics matching those of pyrroloquinoline quinone (PQQ) for extracellular electron transfer. The latter appears to utilise outer membrane-bound redox compounds. Interaction of quinones and cytochromes with the membrane-bound electron transfer chain is yet to be proven.

  15. Models of fast-electron penetration

    International Nuclear Information System (INIS)

    Perry, D.J.; Raisis, S.K.

    1994-01-01

    We introduce multiple scattering models of charged-particle penetration which are based on the previous analyses of Yang and Perry. Our development removes the main limitations of the Fermi-Eyges approach while retaining its considerable potential as a theory which is useful for applied work. We illustrate key predictions with sample calculations that are of particular interest in therapeutic applications, 5-20 MeV electrons incident on water. 8 refs., 5 figs

  16. INVERSE ELECTRON TRANSFER IN PEROXYOXALATE CHEMIEXCITATION USING EASILY REDUCIBLE ACTIVATORS

    NARCIS (Netherlands)

    Bartoloni, Fernando Heering; Monteiro Leite Ciscato, Luiz Francisco; Augusto, Felipe Alberto; Baader, Wilhelm Josef

    2010-01-01

    INVERSE ELECTRON TRANSFER IN PEROXYOXALATE CHEMIEXCITATION USING EASILY REDUCIBLE ACTIVATORS. Chemiluminescence properties of the peroxyoxalate reaction in the presence of activators bearing electron withdrawing substituents were studied, to evaluate the possible occurrence of an inverse electron

  17. Experimental study of fast electron transport in dense plasmas

    International Nuclear Information System (INIS)

    Vaisseau, Xavier

    2014-01-01

    The framework of this PhD thesis is the inertial confinement fusion for energy production, in the context of the electron fast ignition scheme. The work consists in a characterization of the transport mechanisms of fast electrons, driven by intense laser pulses (10 19 - 10 20 W/cm 2 ) in both cold-solid and warm-dense matter. The first goal was to study the propagation of a fast electron beam, characterized by a current density ≥ 10 11 A/cm 2 , in aluminum targets initially heated close to the Fermi temperature by a counter-propagative planar shock. The planar compression geometry allowed us to discriminate the energy losses due to the resistive mechanisms from collisional ones by comparing solid and compressed targets of the same initial areal densities. We observed for the first time a significant increase of resistive energy losses in heated aluminum samples. The confrontation of the experimental data with the simulations, including a complete characterization of the electron source, of the target compression and of the fast electron transport, allowed us to study the time-evolution of the material resistivity. The estimated resistive electron stopping power in a warm-compressed target is of the same order as the collisional one. We studied the transport of the fast electrons generated in the interaction of a high-contrast laser pulse with a hollow copper cone, buried into a carbon layer, compressed by a counter-propagative planar shock. A X-ray imaging system allowed us to visualize the coupling of the laser pulse with the cone at different moments of the compression. This diagnostic, giving access to the fast electron spatial distribution, showed a fast electron generation in the entire volume of the cone for late times of compression, after shock breakout from the inner cone tip. For earlier times, the interaction at a high-contrast ensured that the source was contained within the cone tip, and the fast electron beam was collimated into the target depth by

  18. Fast electron generation and transport in a turbulent, magnetized plasma

    International Nuclear Information System (INIS)

    Stoneking, W.R.

    1994-05-01

    The nature of fast electron generation and transport in the Madison Symmetric Torus (MST) reversed field pinch (RFP) is investigated using two electron energy analyzer (EEA) probes and a thermocouple calorimeter. The parallel velocity distribution of the fast electron population is well fit by a drifted Maxwellian distribution with temperature of about 100 eV and drift velocity of about 2 x 10 6 m/s. Cross-calibration of the EEA with the calorimeter provides a measurement of the fast electron perpendicular temperature of 30 eV, much lower than the parallel temperature, and is evidence that the kinetic dynamo mechanism (KDT) is not operative in MST. The fast electron current is found to match to the parallel current at the edge, and the fast electron density is about 4 x 10 11 cm -3 independent of the ratio of the applied toroidal electric field to the critical electric field for runaways. First time measurements of magnetic fluctuation induced particle transport are reported. By correlating electron current fluctuations with radial magnetic fluctuations the transported flux of electrons is found to be negligible outside r/a∼0.9, but rises the level of the expected total particle losses inside r/a∼0.85. A comparison of the measured diffusion coefficient is made with the ausilinear stochastic diffusion coefficient. Evidence exists that the reduction of the transport is due to the presence of a radial ambipolar electric field of magnitude 500 V/m, that acts to equilibrate the ion and electron transport rates. The convective energy transport associated with the measured particle transport is large enough to account for the observed magnetic fluctuation induced energy transport in MST

  19. Reaction of electron-transfer flavoprotein with electron-transfer flavoprotein-ubiquinone oxidoreductase

    International Nuclear Information System (INIS)

    Beckmann, J.D.; Frerman, F.E.

    1985-01-01

    The oxidative half-reaction of electron-transfer flavoprotein (ETF), electron transfer from ETF to electron-transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO), is dependent on complementary surface charges on the two proteins. ETF is the positively charged member of the redox pair. The evidence is based on the pH and ionic strength dependencies of the comproportionation of oxidized ETF and ETF hydroquinone catalyzed by ETF-QO and on the effects of chemical modification of ETF on the comproportionation reaction. Acetylation of one and five epsilon-amino groups of lysyl residues results in 3- and 13-fold increases, respectively, in the K/sub m/ of ETF-QO for ETF but no change in V/sub max/. Amidination, which maintains positive charge at modified loci, has no effect on steady-state kinetic constants. These chemical modifications have no effect on the equilibrium constant for equilibration of ETF redox states. The K/sub m/ of ETF-QO for ETF is pH dependent above pH 8.5, suggesting titration of lysyl residues. The ionic strength dependence of TN/KmETF for the reaction follows the limiting Bronsted equation. The ETF-QO-catalyzed comproportionation reaction exhibits a primary deuterium isotope effect in D 2 O, perhaps indicating the participation of solvent water in the electron-transfer reaction

  20. Ultra-fast electron capture by electrosterically-stabilized gold nanoparticles.

    Science.gov (United States)

    Ghandi, Khashayar; Findlater, Alexander D; Mahimwalla, Zahid; MacNeil, Connor S; Awoonor-Williams, Ernest; Zahariev, Federico; Gordon, Mark S

    2015-07-21

    Ultra-fast pre-solvated electron capture has been observed for aqueous solutions of room-temperature ionic liquid (RTIL) surface-stabilized gold nanoparticles (AuNPs; ∼9 nm). The extraordinarily large inverse temperature dependent rate constants (k(e)∼ 5 × 10(14) M(-1) s(-1)) measured for the capture of electrons in solution suggest electron capture by the AuNP surface that is on the timescale of, and therefore in competition with, electron solvation and electron-cation recombination reactions. The observed electron transfer rates challenge the conventional notion that radiation induced biological damage would be enhanced in the presence of AuNPs. On the contrary, AuNPs stabilized by non-covalently bonded ligands demonstrate the potential to quench radiation-induced electrons, indicating potential applications in fields ranging from radiation therapy to heterogeneous catalysis.

  1. Electron transfer in gas surface collisions

    International Nuclear Information System (INIS)

    Wunnik, J.N.M. van.

    1983-01-01

    In this thesis electron transfer between atoms and metal surfaces in general is discussed and the negative ionization of hydrogen by scattering protons at a cesiated crystalline tungsten (110) surface in particular. Experimental results and a novel theoretical analysis are presented. In Chapter I a theoretical overview of resonant electron transitions between atoms and metals is given. In the first part of chapter II atom-metal electron transitions at a fixed atom-metal distance are described on the basis of a model developed by Gadzuk. In the second part the influence of the motion of the atom on the atomic charge state is incorporated. Measurements presented in chapter III show a strong dependence of the fraction of negatively charged H atoms scattered at cesiated tungsten, on the normal as well as the parallel velocity component. In chapter IV the proposed mechanism for the parallel velocity effect is incorporated in the amplitude method. The scattering process of protons incident under grazing angles on a cesium covered surface is studied in chapter V. (Auth.)

  2. Quantum tunneling resonant electron transfer process in Lorentzian plasmas

    International Nuclear Information System (INIS)

    Hong, Woo-Pyo; Jung, Young-Dae

    2014-01-01

    The quantum tunneling resonant electron transfer process between a positive ion and a neutral atom collision is investigated in nonthermal generalized Lorentzian plasmas. The result shows that the nonthermal effect enhances the resonant electron transfer cross section in Lorentzian plasmas. It is found that the nonthermal effect on the classical resonant electron transfer cross section is more significant than that on the quantum tunneling resonant charge transfer cross section. It is shown that the nonthermal effect on the resonant electron transfer cross section decreases with an increase of the Debye length. In addition, the nonthermal effect on the quantum tunneling resonant electron transfer cross section decreases with increasing collision energy. The variation of nonthermal and plasma shielding effects on the quantum tunneling resonant electron transfer process is also discussed

  3. GPU-accelerated computation of electron transfer.

    Science.gov (United States)

    Höfinger, Siegfried; Acocella, Angela; Pop, Sergiu C; Narumi, Tetsu; Yasuoka, Kenji; Beu, Titus; Zerbetto, Francesco

    2012-11-05

    Electron transfer is a fundamental process that can be studied with the help of computer simulation. The underlying quantum mechanical description renders the problem a computationally intensive application. In this study, we probe the graphics processing unit (GPU) for suitability to this type of problem. Time-critical components are identified via profiling of an existing implementation and several different variants are tested involving the GPU at increasing levels of abstraction. A publicly available library supporting basic linear algebra operations on the GPU turns out to accelerate the computation approximately 50-fold with minor dependence on actual problem size. The performance gain does not compromise numerical accuracy and is of significant value for practical purposes. Copyright © 2012 Wiley Periodicals, Inc.

  4. Charge transfer in gas electron multipliers

    Energy Technology Data Exchange (ETDEWEB)

    Ottnad, Jonathan; Ball, Markus; Ketzer, Bernhard; Ratza, Viktor; Razzaghi, Cina [HISKP, Bonn University, Nussallee 14-16, D-53115 Bonn (Germany)

    2015-07-01

    In order to efficiently employ a Time Projection Chamber (TPC) at interaction rates higher than ∝1 kHz, as foreseen e.g. in the ALICE experiment (CERN) and at CB-ELSA (Bonn), a continuous operation and readout mode is required. A necessary prerequisite is to minimize the space charge coming from the amplification system and to maintain an excellent spatial and energy resolution. Unfortunately these two goals can be in conflict to each other. Gas Electron Multipliers (GEM) are one candidate to fulfill these requirements. It is necessary to understand the processes within the amplification structure to find optimal operation conditions. To do so, we measure the charge transfer processes in and between GEM foils with different geometries and field configurations, and use an analytical model to describe the results. This model can then be used to predict and optimize the performance. The talk gives the present status of the measurements and describes the model.

  5. Direct electron transfer based enzymatic fuel cells

    International Nuclear Information System (INIS)

    Falk, Magnus; Blum, Zoltan; Shleev, Sergey

    2012-01-01

    In this mini-review we briefly describe some historical developments made in the field of enzymatic fuel cells (FCs), discussing important design considerations taken when constructing mediator-, cofactor-, and membrane-less biological FCs (BFCs). Since the topic is rather extensive, only BFCs utilizing direct electron transfer (DET) reactions on both the anodic and cathodic sides are considered. Moreover, the performance of mostly glucose/oxygen biodevices is analyzed and compared. We also present some unpublished results on mediator-, cofactor-, and membrane-less glucose/oxygen BFCs recently designed in our group and tested in different human physiological fluids, such as blood, plasma, saliva, and tears. Finally, further perspectives for BFC applications are highlighted.

  6. Arbitrary amplitude fast electron-acoustic solitons in three-electron component space plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Mbuli, L. N.; Maharaj, S. K. [South African National Space Agency (SANSA) Space Science, P.O. Box 32, Hermanus 7200, Republic of South Africa (South Africa); Department of Physics, University of the Western Cape (UWC), Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa); Bharuthram, R. [Department of Physics, University of the Western Cape (UWC), Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa); Singh, S. V.; Lakhina, G. S. [Indian Institute of Geomagnetism, New Panvel (West), Navi Mumbai 410218 (India); Department of Physics, University of the Western Cape (UWC), Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa)

    2016-06-15

    We examine the characteristics of fast electron-acoustic solitons in a four-component unmagnetised plasma model consisting of cool, warm, and hot electrons, and cool ions. We retain the inertia and pressure for all the plasma species by assuming adiabatic fluid behaviour for all the species. By using the Sagdeev pseudo-potential technique, the allowable Mach number ranges for fast electron-acoustic solitary waves are explored and discussed. It is found that the cool and warm electron number densities determine the polarity switch of the fast electron-acoustic solitons which are limited by either the occurrence of fast electron-acoustic double layers or warm and hot electron number density becoming unreal. For the first time in the study of solitons, we report on the coexistence of fast electron-acoustic solitons, in addition to the regular fast electron-acoustic solitons and double layers in our multi-species plasma model. Our results are applied to the generation of broadband electrostatic noise in the dayside auroral region.

  7. The description of charge transfer in fast negative ions scattering on water covered Si(100) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lin; Qiu, Shunli; Liu, Pinyang; Xiong, Feifei; Lu, Jianjie; Liu, Yuefeng; Li, Guopeng; Liu, Yiran; Ren, Fei; Xiao, Yunqing; Gao, Lei; Zhao, Qiushuang; Ding, Bin; Li, Yuan [School of Nuclear Science and Technology, Lanzhou University, 730000 (China); Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 (China); Guo, Yanling, E-mail: guoyanling@lzu.edu.cn [School of Nuclear Science and Technology, Lanzhou University, 730000 (China); Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 (China); Chen, Ximeng, E-mail: chenxm@lzu.edu.cn [School of Nuclear Science and Technology, Lanzhou University, 730000 (China); Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 (China)

    2016-11-30

    Highlights: • We first observe that negative-ion fractions present no variation with the doping concentration, which is very different from the results of low energy Li neutralization from doped Si samples. • Our work shows that the affinity levels and collision time significantly counteract the band gap effect on negative ion formation. The work will improve our understanding on electron transfer on semiconductor surfaces associated with doping. • In addition, we build a complete theoretical framework to quantitatively calculate the negative-ion fractions. • Our work is related to charge transfer on semiconductor surfaces, which will be of interest to a broad audience due to the wide necessity of the knowledge of charge exchange on semiconductor surfaces in different fields. - Abstract: Doping has significantly affected the characteristics and performance of semiconductor electronic devices. In this work, we study the charge transfer processes for 8.5–22.5 keV C{sup −} and F{sup −} ions scattering on H{sub 2}O-terminated p-type Si(100) surfaces with two different doping concentrations. We find that doping has no influence on negative-ion formation for fast collisions in this relatively high energy range. Moreover, we build a model to calculate negative ion fractions including the contribution from positive ions. The calculations support the nonadiabatic feature of charge transfer.

  8. 14 CFR 1274.931 - Electronic funds transfer payment methods.

    Science.gov (United States)

    2010-01-01

    ... cooperative agreement will be made by the Government by electronic funds transfer through the Treasury Fedline... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Electronic funds transfer payment methods... COOPERATIVE AGREEMENTS WITH COMMERCIAL FIRMS Other Provisions and Special Conditions § 1274.931 Electronic...

  9. Designed azurins show lower reorganization free energies for intraprotein electron transfer

    DEFF Research Database (Denmark)

    Farver, Ole; Marshall, Nicholas M; Wherland, Scot

    2013-01-01

    Low reorganization free energies are necessary for fast electron transfer (ET) reactions. Hence, rational design of redox proteins with lower reorganization free energies has been a long-standing challenge, promising to yield a deeper understanding of the underlying principles of ET reactivity...

  10. Electronic excitations in fast ion-solid collisions

    International Nuclear Information System (INIS)

    Burgdoerfer, J.

    1990-01-01

    We review recent developments in the study of electronic excitation of projectiles in fast ion-solid collisions. Our focus will be primarily on theory but experimental advances will also be discussed. Topics include the evidence for velocity-dependent thresholds for the existence of bound states, wake-field effects on excited states, the electronic excitation of channeled projectiles, transport phenomena, and the interaction of highly charged ions with surfaces. 44 refs., 14 figs

  11. Summary: Electron-cloud effects and fast-ion instability

    International Nuclear Information System (INIS)

    Furman, Miguel A.

    2000-01-01

    This is my summary of the talks on the electron-cloud effect and the fast-ion instability that were presented at the 8th ICFA Beam Dynamics Mini-Work shop on Two-Stream Instabilities in Particle Accelerators and Storage Rings,Santa Fe, NM, February 16--18, 2000

  12. Characteristics of the fast electron emission produced during the ...

    Indian Academy of Sciences (India)

    water adsorption and other characteristics of the fast electron emission ..... that the surface charges which leak away when there is adosrbed water on ... implies that it is a measure of the supply of excited species rather than due to the charge.

  13. A thermodynamical analysis of rf current drive with fast electrons

    Energy Technology Data Exchange (ETDEWEB)

    Bizarro, João P. S., E-mail: bizarro@ipfn.tecnico.ulisboa.pt [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal)

    2015-08-15

    The problem of rf current drive (CD) by pushing fast electrons with high-parallel-phase-velocity waves, such as lower-hybrid (LH) or electron-cyclotron (EC) waves, is revisited using the first and second laws, the former to retrieve the well-known one-dimensional (1D) steady-state CD efficiency, and the latter to calculate a lower bound for the rate of entropy production when approaching steady state. The laws of thermodynamics are written in a form that explicitly takes care of frictional dissipation and are thus applied to a population of fast electrons evolving under the influence of a dc electric field, rf waves, and collisions while in contact with a thermal, Maxwellian reservoir with a well-defined temperature. Besides the laws of macroscopic thermodynamics, there is recourse to basic elements of kinetic theory only, being assumed a residual dc electric field and a strong rf drive, capable of sustaining in the resonant region, where waves interact with electrons, a raised fast-electron tail distribution, which becomes an essentially flat plateau in the case of the 1D theory for LHCD. Within the 1D model, particularly suited for LHCD as it solely retains fast-electron dynamics in velocity space parallel to the ambient magnetic field, an H theorem for rf CD is also derived, which is written in different forms, and additional physics is recovered, such as the synergy between the dc and rf power sources, including the rf-induced hot conductivity, as well as the equation for electron-bulk heating. As much as possible 1D results are extended to 2D, to account for ECCD by also considering fast-electron velocity-space dynamics in the direction perpendicular to the magnetic field, which leads to a detailed discussion on how the definition of an rf-induced conductivity may depend on whether one works at constant rf current or power. Moreover, working out the collisional dissipated power and entropy-production rate written in terms of the fast-electron distribution, it

  14. Electron transfer reactions of metal complexes in solution

    International Nuclear Information System (INIS)

    Sutin, N.

    1977-01-01

    A few representative electron-transfer reactions are selected and their kinetic parameters compared with the predictions of activated complex models. Since Taube has presented an elegant treatment of intramolecular electron-transfer reactions, emphasis is on bimolecular reactions. The latter electron-transfer reactions are more complicated to treat theoretically since the geometries of their activated complexes are not as well known as for the intramolecular case. In addition in biomolecular reactions, the work required to bring the two reactants together needs to be calculated. Since both reactants generally carry charges this presents a non-trivial problem at the ionic strengths usually used to study bimolecular electron transfer

  15. Model potentials in liquid water ionization by fast electron impact

    International Nuclear Information System (INIS)

    De Sanctis, M L; Stia, C R; Fojón, O A; Politis, M-F; Vuilleumier, R

    2015-01-01

    We study the ionization of water molecules in liquid phase by fast electron impact. We use our previous first-order model within an independent electron approximation that allows the reduction of the multielectronic problem into a monoelectronic one. The initial molecular states of the liquid water are represented in a realistic way through a Wannier orbital formalism. We complete our previous study by taking into account approximately the influence of the passive electrons of the target by means of different model potentials. We compute multiple differential cross sections for the most external orbital 1B 1 and compare them with other results

  16. Experimental study of fast electron transport in the framework of fast ignition for inertial fusion

    International Nuclear Information System (INIS)

    Vauzour, B.

    2012-01-01

    The framework of this PhD thesis is the validation of the fast ignition scheme for the nuclear fusion by inertial confinement. It consists in the experimental study of the various processes involved in fast electron beams propagation, produced by intense laser pulses (10 19 W.cm -2 ), through dense matter either solid or compressed. In this work we present the results of three experiments carried out on different laser facilities in order to generate fast electron beams in various conditions and study their propagation in different states of matter, from the cold solid to the warm and dense plasma.The first experiment was performed with a high intensity contrast on the UHI100 laser facility (CEA Saclay). The study of fast electron energy deposition inside thin aluminium targets highlights a strong target heating at shallow depths, where the collective effects are predominant, thus producing a steep temperature profile between front (300 eV) and rear (20 eV) sides over 20μm thickness. A numerical simulation of the experiment shows that this temperature gradient induces the formation of a shock wave, breaking through the rear side of the target and thus leading to increase the thermal emission. The experimental chronometry of the shock breakthrough allowed validating the model of the collective transport of electrons.Two other experiments were dedicated to the study of fast electron beam propagation inside compressed targets. In the first experiment on the LULI2000 laser facility, the plane compression geometry allowed to precisely dissociate the energy losses due to resistive effects from those due to the collisional ones. By comparing our experimental results with simulations, we observed a significative increase of the fast electron beam energy losses with the compression and the target heating to temperatures close to the Fermi temperature. The second experiment, performed in a cylindrical geometry, demonstrated a fast electron beam guiding phenomenon due to

  17. Study of fast electrons from hard-X radiation

    International Nuclear Information System (INIS)

    Arslanbekov, R.

    1995-01-01

    The goal of this thesis is the study of fast electron dynamics by means of the hard X-ray diagnosis installed in TORE SUPRA and numerical simulations. Fast electrons are generated in the plasma in the presence of the injected lower hybrid (LH) waves. Two aspects are studied in detail: the lower hybrid wave propagation and absorption in a periodically perturbed media and 2-D Fokker-Planck modelling of the fast electron dynamics in the presence of the LH power. Ripple effects on lower hybrid wave propagation and absorption are investigated using the ray tracing technique. A cylindrical equilibrium is first studied and a strong modification of the ray dynamics is predicted. Calculations are carried out in a real toroidal geometry corresponding to TORE SUPRA. It is shown that the lack of toroidal axisymmetry of the magnetic field may result in a modification of the ray evolution even if the global ray evolution is governed by the larger poloidal inhomogeneity. Simulation of LH experiments are performed for TORE SUPRA tokamak which has a large magnetic ripple (7% at the plasma edge). By considering ripple perturbation in LH current drive simulations, a better agreement is found with experimental results, in particular with the hard-X spectra and the current density profiles. In the second part of the thesis, a 2-D modeling of the fast electron dynamics in the velocity phase space is considered, based on the 2-D relativistic electron Fokker-Planck equation. Electron distribution functions obtained are used to calculate non-thermal Bremsstrahlung emission for different TORE SUPRA shots in a wide range of experimental conditions. (J.S.). 168 refs., 93 figs., 1 tab., 3 appendix

  18. Modified Sternglass theory for the emission of secondary electrons by fast-electron impact

    International Nuclear Information System (INIS)

    Suszcynsky, D.M.; Borovsky, J.E.

    1992-01-01

    The Sternglass theory [Sternglass, Phys. Rev. 108, 1 (1957)] for fast-ion-induced secondary-electron emission from metals has been modified to predict the secondary-electron yield from metals impacted by energetic (several keV to about 200 keV) electrons. The primary modification of the theory accounts for the contribution of the backscattered electrons to the production of secondary electrons based on a knowledge of the backscattered-electron energy distribution. The modified theory is in reasonable agreement with recent experimental data from gold targets in the 6--30-keV electron energy range

  19. Mechanism of Intermolecular Electron Transfer in Bionanostructures

    Science.gov (United States)

    Gruodis, A.; Galikova, N.; Šarka, K.; Saulė, R.; Batiuškaitė, D.; Saulis, G.

    Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. Most patients are inoperable and hepatoma cells are resistant to conventional chemotherapies. Thus, the development of novel therapies for HCC treatment is of paramount importance. Amongst different alimentary factors, vitamin C and vitamin K3 In the present work, it has been shown that the treatment of mouse hepatoma MH-22A cells by vitamin C and vitamin K3 at the ratio of 100:1 greatly enhanced their cytotoxicity. When cells were subjected to vitamin C at 200 μM or to vitamin K3 at 2 μM separately, their viability reduced by only about 10%. However, when vitamins C and K3 were combined at the same concentrations, they killed more than 90% of cells. To elucidate the mechanism of the synergistic cytotoxicity of the C&K3 mixture, theoretical quantum-chemical analysis of the dynamics of intermolecular electron transfer (IET) processes within the complexes containing C (five forms) and K3 (one form) has been carried out. Optimization of the ground state complex geometry has been provided by means of GAUSSIAN03 package. Simulation of the IET has been carried out using NUVOLA package, in the framework of molecular orbitals (MO). The rate of IET has been calculated using Fermi Golden rule. The results of simulations allow us to create the preliminary model of the reaction pathway.

  20. Electronic transfer of sensitive patient data.

    Science.gov (United States)

    Detterbeck, A M W; Kaiser, J; Hirschfelder, U

    2015-01-01

    The purpose of this study was to develop decision-making aids and recommendations for dental practitioners regarding the utilization and sharing of sensitive digital patient data. In the current environment of growing digitization, healthcare professionals need detailed knowledge of secure data management to maximize confidentiality and minimize the risks involved in both archiving patient data and sharing it through electronic channels. Despite well-defined legal requirements, an all-inclusive technological solution does not currently exist. The need for a preliminary review and critical appraisal of common practices of data transfer prompted a search of the literature and the Web to identify viable methods of secure data exchange and to develop a flowchart. A strong focus was placed on the transmission of datasets both smaller than and larger than 10 MB, and on secure communication by smartphone. Although encryption of patient-related data should be routine, it is often difficult to implement. Pretty Good Privacy (PGP) and Secure/Multipurpose Internet Mail Extensions (S/MIME) are viable standards for secure e-mail encryption. Sharing of high-volume data should be accomplished with the help of file encryption. Careful handling of sensitive patient data is mandatory, and it is the end-user's responsibility to meet any requirements for encryption, preferably by using free, open-source (and hence transparent) software.

  1. Collisions of fast multicharged ions in gas targets: charge transfer and ionization

    International Nuclear Information System (INIS)

    Schlachter, A.S.

    1981-05-01

    Measurements of cross sections for charge transfer and ionization of H 2 and rare-gas targets have been made with fast, highly stripped projectiles in charge states as high as 59+. We have found an empirical scaling rule for electron-capture cross section in H 2 valid at energies above 275 keV/amu. Similar scaling might exist for other target gases. Cross sections are generally in good agreement with theory. We have found a scaling rule for electron loss from H in collisions with a fast highly stripped projectile, based on Olson's classical-trajectory Monte-Carlo calculations, and confirmed by measurements in an H 2 target. We have found a similar scaling rule for net ionization of rare-gas targets, based on Olson's CTMC calculations and the independent-electron model. Measurements are essentially consistent with the scaled cross sections. Calculations and measurements of recoil-ion charge-state spectra show large cross sections for the production of highly charged slow recoil ions

  2. Pulsed electron beam generation with fast repetitive double pulse system

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Surender Kumar; Deb, Pankaj; Shyam, Anurag, E-mail: surender80@gmail.com [Energetics and Electromagnetics Division, Bhabha Atomic Research Centre, Visakhapatnam (India); Sharma, Archana [Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Mumbai (India)

    2014-07-01

    Longer duration high voltage pulse (∼ 100 kV, 260 ns) is generated and reported using helical pulse forming line in compact geometry. The transmission line characteristics of the helical pulse forming line are also used to develop fast repetition double pulse system with very short inter pulse interval. It overcomes the limitations caused due to circuit parameters, power supplies and load characteristics for fast repetitive high voltage pulse generation. The high voltage double pulse of 100 kV, 100 ns with an inter pulse repetition interval of 30 ns is applied across the vacuum field emission diode for pulsed electron beam generation. The electron beam is generated from cathode material by application of negative high voltage (> 100 kV) across the diode by explosive electron emission process. The vacuum field emission diode is made of 40 mm diameter graphite cathode and SS mesh anode. The anode cathode gap was 6 mm and the drift tube diameter was 10 cm. The initial experimental results of pulsed electron beam generation with fast repetitive double pulse system are reported and discussed. (author)

  3. Fast electron and X-ray scattering as a tool to study target's structure

    International Nuclear Information System (INIS)

    Amusia, M.Ya.

    2007-01-01

    We concentrate on several relatively new aspects of the study of fast electron and X-ray scattering by atoms and atom-like objects, namely endohedral atoms and fullerenes. However, main attention is given to fast charge particle scattering. We show that the corresponding cross-sections, being expressed via so-called generalized oscillator strengths (GOS), give information on the electronic structure of the target and on the role of electron correlations in it. We consider what sort of information became available when analyzing the dependence of GOS upon their multipolarity, transferred momentum q and energy ω. To obtain theoretical results, we employ both the one-electron Hartree-Fock approximation and account for the multi-electron correlation in the target, using the random phase approximation with exchange. We demonstrate the role of non-dipole corrections in the small-angle fast-electron inelastic scattering. There dipole contribution dominates while non-dipole corrections can be considerably and controllably enhanced as compared to the case of low and medium energy photoionization. We show also that analyses of GOS for discrete level excitations permit to clarify their multipolarity. The results of calculations of Compton excitation and ionization cross-sections are presented. Attention is given to cooperative effects in inelastic fast electron-atom scattering that results in directed motion of the secondary electrons, a phenomenon that is similar to 'drag currents' in photoionization. We demonstrate how one should derive GOS for endohedral atoms, e.g. A-C 60 and what is the additional information that can be obtained from corresponding GOS. Most of discussions are illustrated by the results of concrete calculations

  4. Coupled sensitizer-catalyst dyads: electron-transfer reactions in a perylene-polyoxometalate conjugate.

    Science.gov (United States)

    Odobel, Fabrice; Séverac, Marjorie; Pellegrin, Yann; Blart, Errol; Fosse, Céline; Cannizzo, Caroline; Mayer, Cédric R; Elliott, Kristopher J; Harriman, Anthony

    2009-01-01

    Ultrafast discharge of a single-electron capacitor: A variety of intramolecular electron-transfer reactions are apparent for polyoxometalates functionalized with covalently attached perylene monoimide chromophores, but these are restricted to single-electron events. (et=electron transfer, cr=charge recombination, csr=charge-shift reaction, PER=perylene, POM=polyoxometalate).A new strategy is introduced that permits covalent attachment of an organic chromophore to a polyoxometalate (POM) cluster. Two examples are reported that differ according to the nature of the anchoring group and the flexibility of the linker. Both POMs are functionalized with perylene monoimide units, which function as photon collectors and form a relatively long-lived charge-transfer state under illumination. They are reduced to a stable pi-radical anion by electrolysis or to a protonated dianion under photolysis in the presence of aqueous triethanolamine. The presence of the POM opens up an intramolecular electron-transfer route by which the charge-transfer state reduces the POM. The rate of this process depends on the molecular conformation and appears to involve through-space interactions. Prior reduction of the POM leads to efficient fluorescence quenching, again due to intramolecular electron transfer. In most cases, it is difficult to resolve the electron-transfer products because of relatively fast reverse charge shift that occurs within a closed conformer. Although the POM can store multiple electrons, it has not proved possible to use these systems as molecular-scale capacitors because of efficient electron transfer from the one-electron-reduced POM to the excited singlet state of the perylene monoimide.

  5. Collimated fast electron beam generation in critical density plasma

    Energy Technology Data Exchange (ETDEWEB)

    Iwawaki, T., E-mail: iwawaki-t@eie.eng.osaka-u.ac.jp; Habara, H.; Morita, K.; Tanaka, K. A. [Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871 (Japan); Baton, S.; Fuchs, J.; Chen, S. [LULI, CNRS-Ecole Polytechnique-Université Pierre et Marie Curie-CEA, 91128 Palaiseau (France); Nakatsutsumi, M. [LULI, CNRS-Ecole Polytechnique-Université Pierre et Marie Curie-CEA, 91128 Palaiseau (France); European X-Ray Free-Electron Laser Facility (XFEL) GmbH (Germany); Rousseaux, C. [CEA, DAM, DIF, F-91297 Arpajon (France); Filippi, F. [La SAPIENZA, University of Rome, Dip. SBAI, 00161 Rome (Italy); Nazarov, W. [School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9ST, Scotland (United Kingdom)

    2014-11-15

    Significantly collimated fast electron beam with a divergence angle 10° (FWHM) is observed when an ultra-intense laser pulse (I = 10{sup 14 }W/cm{sup 2}, 300 fs) irradiates a uniform critical density plasma. The uniform plasma is created through the ionization of an ultra-low density (5 mg/c.c.) plastic foam by X-ray burst from the interaction of intense laser (I = 10{sup 14 }W/cm{sup 2}, 600 ps) with a thin Cu foil. 2D Particle-In-Cell (PIC) simulation well reproduces the collimated electron beam with a strong magnetic field in the region of the laser pulse propagation. To understand the physical mechanism of the collimation, we calculate energetic electron motion in the magnetic field obtained from the 2D PIC simulation. As the results, the strong magnetic field (300 MG) collimates electrons with energy over a few MeV. This collimation mechanism may attract attention in many applications such as electron acceleration, electron microscope and fast ignition of laser fusion.

  6. 76 FR 709 - Electronic Funds Transfer of Depository Taxes; Correction

    Science.gov (United States)

    2011-01-06

    ... DEPARTMENT OF THE TREASURY Internal Revenue Service 26 CFR Parts 40 and 301 [TD 9507] RIN 1545-BJ13 Electronic Funds Transfer of Depository Taxes; Correction AGENCY: Internal Revenue Service (IRS...) providing guidance relating to Federal tax deposits (FTDs) by Electronic Funds Transfer (EFT). The temporary...

  7. 76 FR 708 - Electronic Funds Transfer of Depository Taxes; Correction

    Science.gov (United States)

    2011-01-06

    ... DEPARTMENT OF THE TREASURY Internal Revenue Service 26 CFR Parts 1, 31, 40, and 301 [TD 9507] RIN 1545-BJ13 Electronic Funds Transfer of Depository Taxes; Correction AGENCY: Internal Revenue Service... Electronic Funds Transfer (EFT). The temporary and final regulations provide rules under which depositors...

  8. 78 FR 66251 - Electronic Fund Transfers(Regulation E)

    Science.gov (United States)

    2013-11-05

    ... Electronic Fund Transfers (Regulation E) AGENCY: Bureau of Consumer Financial Protection. ACTION: Notice of... subpart B of Regulation E, which implements the Electronic Fund Transfer Act, and published this list on...-rule-amendment-to-regulation-e/ . SUPPLEMENTARY INFORMATION: The Bureau published its remittance rule...

  9. 78 FR 49365 - Electronic Fund Transfers (Regulation E); Correction

    Science.gov (United States)

    2013-08-14

    ... BUREAU OF CONSUMER FINANCIAL PROTECTION 12 CFR Part 1005 [Docket No. CFPB-2012-0050] RIN 3170-AA33 Electronic Fund Transfers (Regulation E); Correction AGENCY: Bureau of Consumer Financial Protection. ACTION... 2013 Final Rule, which along with three other final rules \\1\\ implements the Electronic Fund Transfer...

  10. THE ELECTRONIC COURSE OF HEAT AND MASS TRANSFER

    Directory of Open Access Journals (Sweden)

    Alexander P. Solodov

    2013-01-01

    Full Text Available The Electronic course of heat and mass transfer in power engineering is presented containing the full Electronic book as the structured hypertext document, the full set of Mathcad-documents with the whole set of educative computer models of heat and mass transfer, the computer labs, and selected educational presentations. 

  11. Inelastic electron scattering at low momentum transfer

    International Nuclear Information System (INIS)

    Richter, A.

    1979-01-01

    Recent advances of high energy resolution (ΔE approx. 30 keV FWHM) inelastic electron scattering at low momentum transfer (q -1 ) using selected experimental data from the Darmstadt electron linear accelerator are discussed. Strong emphasis is given to a comparison of the data with theoretical nuclear model predictions. Of the low multipolarity electric transitions investigated, as examples only E1 transitions to unnatural parity states in 11 B and E2 transitions of the very fragmented isoscalar quadrupole giant resonance in 208 Pb are considered. In 11 B the role of the Os hole in the configuration of the 1/2 + , 3/2 + and 5/2 + states is quantitatively determined via an interference mechanism in the transition probability. By comparison of the high resolution data with RPA calculations the E2 EWSR in 208 Pb is found to be much less exhausted than anticipated from previous medium energy resolution (e,e) and hadron scattering experiments. In the case of M1 transitions it is shown that the simplest idealized independent particle shell-model prediction breaks down badly. In 28 Si, ground-state correlations influence largely the detected M1 strength and such ground-state correlations are also responsible for the occurence of a strong M1 transition to a state at Ex = 10.319 MeV in 40 Ca. In 90 Zr only about 10% of the theoretically expected M1 strength is seen in (e,e) and in 140 Ce and 208 Pb none (detection limit 1-2 μ 2 K). In the case of 208 Pb high resolution spectra exist now up to an excitation energy of Ex = approx. 12MeV. The continuous decrease of the M1 strength with mass number is corroborated by the behaviour of strong but very fragmented M2 transitions which are detected in 28 Si, 90 Zr, 140 Ce and 208 Pb concentrated at an excitation energy E x approx. 44A -1 / 3 MeV. In 90 Zr, the distribution of spacings and widths of the many Jπ = 2 states are consistent with a Wigner and Porter-Thomas distribution, respectively. (orig.) 891 KBE/orig. 892 ARA

  12. Molecular Insights into Variable Electron Transfer in Amphibian Cryptochrome

    DEFF Research Database (Denmark)

    Sjulstok, Emil; Lüdemann, Gesa; Kubař, Tomáš

    2018-01-01

    are mutated, radical-pair formation is still observed. In this study, we computationally investigate electron-transfer pathways in the X. laevis cryptochrome DASH by extensively equilibrating a previously established homology model using molecular dynamics simulations and then mutating key amino acids......Cryptochrome proteins are activated by the absorption of blue light, leading to the formation of radical pairs through electron transfer in the active site. Recent experimental studies have shown that once some of the amino acid residues in the active site of Xenopus laevis cryptochrome DASH...... involved in the electron transfer. The electron-transfer pathways are then probed by using tight-binding density-functional theory. We report the alternative electron-transfer pathways resolved at the molecular level and, through comparison of amino acid sequences for cryptochromes from different species...

  13. Fast front-end electronics for COMPASS MWPCs

    CERN Document Server

    Colantoni, M L; Ferrero, A; Frolov, V; Grasso, A; Heinz, S; Maggiora, A; Maggiora, M G; Panzieri, D; Popov, A; Tchalyshev, V

    2000-01-01

    In the COMPASS experiment, under construction at CERN, about 23000 channels of MWPCs will be used. The very high rate of the muon and hadron beams, and the consequently high trigger rate, require front- end electronics with innovative conceptual design. A new MWPC front- end electronics that fulfills the main COMPASS requirement to have a fast DAQ with a minimum dead-time has been designed. The general concept of the front-end cards is described; the comparative tests of two front-end chips, and different fast gas mixtures, are also shown. The commissioning of the experiment will start in the summer 2000, and production running, using the muon beam, is foreseen for the year 2001. (8 refs).

  14. Transcriptomic and genetic analysis of direct interspecies electron transfer

    DEFF Research Database (Denmark)

    Shrestha, Pravin Malla; Rotaru, Amelia-Elena; Summers, Zarath M

    2013-01-01

    The possibility that metatranscriptomic analysis could distinguish between direct interspecies electron transfer (DIET) and H2 interspecies transfer (HIT) in anaerobic communities was investigated by comparing gene transcript abundance in cocultures in which Geobacter sulfurreducens....... These results demonstrate that there are unique gene expression patterns that distinguish DIET from HIT and suggest that metatranscriptomics may be a promising route to investigate interspecies electron transfer pathways in more-complex environments....

  15. Photoinduced electron transfer between the dendritic zinc phthalocyanines and anthraquinone

    Science.gov (United States)

    Chen, Kuizhi; Wen, Junri; Liu, Jiangsheng; Chen, Zhenzhen; Pan, Sujuan; Huang, Zheng; Peng, Yiru

    2015-03-01

    The intermolecular electron transfer between the novel dendritic zinc (II) phthalocyanines (G1-DPcB and G2-DPcB) and anthraquinone (AQ) was studied by steady-state fluorescence and UV/Vis absorption spectroscopic methods. The effect of dendron generation on intermolecular electron transfer was investigated. The results showed that the fluorescence emission of these dendritic phthalocyanines could be greatly quenched by AQ upon excitation at 610 nm. The Stern- Volmer constant (KSV) of electron transfer was decreased with increasing the dendron generations. Our study suggested that these novel dendritic phthalocyanines were effective new electron donors and transmission complexes and could be used as a potential artifical photosysthesis system.

  16. Sausage and Kink EMHD Instabilities and Fast Electron transport

    International Nuclear Information System (INIS)

    Das, A.; Jain, N.; Kaw, P.; Sengupta, S.

    2005-01-01

    In the fast ignition concept of laser fusion it is desirable that the hot electron beam generated at the critical layer by the ignitor laser pulse propagates an adequate distance and deposits its energy to the compressed target core in a sufficiently localized region for the creation of hot spot. The mechanisms responsible for energy deposition can be due to (i) the classical coulomb collision cross section and (ii) collective interaction of the beam plasma system. The present work demonstrates a possible electromagnetic turbulence aided collective mechanism of stopping of the energetic electron flow in plasma. (Author)

  17. Electron transfer in organic glass. Distance and energy dependence

    International Nuclear Information System (INIS)

    Krongauz, V.V.

    1992-01-01

    The authors have investigated the distance and energy dependence of electron transfer in rigid organic glasses containing randomly dispersed electron donor and electron acceptor molecules. Pulsed radiolysis by an electron beam from a linear accelerator was used for ionization resulting in charge deposition on donor molecules. The disappearance kinetics of donor radical anions due to electron transfer to acceptor was monitored spectroscopically by the change in optical density at the wavelength corresponding to that of donor radical anion absorbance. It was found that the rate of the electron transfer observed experimentally was higher than that computed using the Marcus-Levich theory assuming that the electron-transfer activation barrier is equal to the binding energy of electron on the donor molecule. This discrepancy between the experimental and computed results suggests that the open-quotes inertclose quotes media in which electron-transfer reaction takes place may be participating in the process, resulting in experimentally observed higher electron-transfer rates. 32 refs., 3 figs., 2 tabs

  18. Treatment of breast cancer recurrence with fast electrons

    Energy Technology Data Exchange (ETDEWEB)

    Gremilov, V A; Svistunova, T M; Migmanova, N Sh [Akademiya Meditsinskikh Nauk SSSR, Leningrad. Inst. Onkologii

    1978-01-01

    Feasibility of treating mammary gland cancer recurrences by means of fast electron is investigated. Local recurrences and metastases were inradiated with 10 MeV fast electrons, and regional ones - with 15 MeV fast electrons. The irradiation technique used permitted the occurence of early and late local radiation responses as well as complications to be avoided. The treatment effect resulted from a value, form and clinical course of recurrence, as well as from cumulative dose with optimum value of 5000-6000 rad. The direct and nearest treatment results in respect of local criterion of the effect are recognized as satisfactory. Taking into consideration, that local and regional recurrences and metastases in the most part of patients are the beginning of clinical manifestation of tumor process generalization, it is assumed, that local treatment of local and regional recurrences and metastases of mammary gland cancer is not reliable therapeutic measure and must be combined with general treatment (chemo- and hormonotherapy) and specific measures enhancing the total resistance of the body.

  19. Fast electron transport study for inertial confinement fusion

    International Nuclear Information System (INIS)

    Touati, Michael

    2015-01-01

    A new hybrid reduced model for relativistic electron beam transport in solids and dense plasmas is presented. It is based on the two first angular moments of the relativistic kinetic equation completed with the Minerbo maximum angular entropy closure. It takes into account collective effects with the self-generated electromagnetic fields as well as collisional effects with the slowing down of the electrons in collisions with plasmons, bound and free electrons and their angular scattering on both ions and electrons. This model allows for fast computations of relativistic electron beam transport while describing the kinetic distribution function evolution. Despite the loss of information concerning the angular distribution of the electron beam, the model reproduces analytical estimates in the academic case of a collimated and monoenergetic electron beam propagating through a warm and dense Hydrogen plasma and hybrid PIC simulation results in a realistic laser-generated electron beam transport in a solid target. The model is applied to the study of the emission of Kα photons in laser-solid experiments and to the generation of shock waves. (author) [fr

  20. Effects of lower hybrid fast electron populations on electron temperature measurements at JET

    International Nuclear Information System (INIS)

    Tanzi, C.P.; Bartlett, D.V.; Schunke, B.

    1993-01-01

    The Lower Hybrid Current Drive (LHCD) system on JET has to date achieved up to 1.5 MA of driven current. This current is carried by a fast electron population with energies more than ten times the electron temperature and density about 10 -4 of the bulk plasma. This paper discusses the effects of this fast electron population on our ability to make reliable temperature measurements using ECE and reviews the effects on other plasma diagnostics which rely on ECE temperature measurements for their interpretation. (orig.)

  1. Multidimensional Quantum Mechanical Modeling of Electron Transfer and Electronic Coherence in Plant Cryptochromes: The Role of Initial Bath Conditions.

    Science.gov (United States)

    Mendive-Tapia, David; Mangaud, Etienne; Firmino, Thiago; de la Lande, Aurélien; Desouter-Lecomte, Michèle; Meyer, Hans-Dieter; Gatti, Fabien

    2018-01-11

    A multidimensional quantum mechanical protocol is used to describe the photoinduced electron transfer and electronic coherence in plant cryptochromes without any semiempirical, e.g., experimentally obtained, parameters. Starting from a two-level spin-boson Hamiltonian we look at the effect that the initial photoinduced nuclear bath distribution has on an intermediate step of this biological electron transfer cascade for two idealized cases. The first assumes a slow equilibration of the nuclear bath with respect to the previous electron transfer step that leads to an ultrafast decay with little temperature dependence; while the second assumes a prior fast bath equilibration on the donor potential energy surface leading to a much slower decay, which contrarily displays a high temperature dependence and a better agreement with previous theoretical and experimental results. Beyond Marcus and semiclassical pictures these results unravel the strong impact that the presence or not of equilibrium initial conditions has on the electronic population and coherence dynamics at the quantum dynamics level in this and conceivably in other biological electron transfer cascades.

  2. Studies of electron and proton isochoric heating for fast ignition

    International Nuclear Information System (INIS)

    Mackinnon, A; Key, M; Akli, K; Beg, F; Clarke, R; Clarke, D; Chen, M; Chung, H; Chen, S; Freeman, R; Green, J; Gu, P; Gregori, G; Highbarger, K; Habara, H; Hatchett, S; Hey, D; Heathcote, R; Hill, J; King, J; Kodama, R; Koch, J; Lancaster, K; Langdon, B; Murphy, C; Norreys, P; Neely, D; Nakatsutsumi, M; Nakamura, H; Patel, N; Patel, P; Pasley, J; Snavley, R; Stephens, R; Stoeckl, C; Foord, M; Tabak, M; Theobald, W; Storm, M; Tanaka, K; Tempo, M; Toley, M; Town, R; Wilks, S; VanWoerkom, L; Weber, R; Yabuuchi, T; Zhang, B

    2006-01-01

    Isochoric heating of inertially confined fusion plasmas by laser driven MeV electrons or protons is an area of great topical interest in the inertial confinement fusion community, particularly with respect to the fast ignition (FI) proposal to use this technique to initiate burn in a fusion capsule. Experiments designed to investigate electron isochoric heating have measured heating in two limiting cases of interest to fast ignition, small planar foils and hollow cones. Data from Cu Kα fluorescence, crystal x-ray spectroscopy of Cu K shell emission, and XUV imaging at 68eV and 256 eV are used to test PIC and Hybrid PIC modeling of the interaction. Isochoric heating by focused proton beams generated at the concave inside surface of a hemi-shell and from a sub hemi-shell inside a cone have been studied with the same diagnostic methods plus imaging of proton induced Kα. Conversion efficiency to protons has also been measured and modeled. Conclusions from the proton and electron heating experiments will be presented. Recent advances in modeling electron transport and innovative target designs for reducing igniter energy and increasing gain curves will also be discussed

  3. A molecular shift register based on electron transfer

    Science.gov (United States)

    Hopfield, J. J.; Onuchic, Josenelson; Beratan, David N.

    1988-01-01

    An electronic shift-register memory at the molecular level is described. The memory elements are based on a chain of electron-transfer molecules and the information is shifted by photoinduced electron-transfer reactions. This device integrates designed electronic molecules onto a very large scale integrated (silicon microelectronic) substrate, providing an example of a 'molecular electronic device' that could actually be made. The design requirements for such a device and possible synthetic strategies are discussed. Devices along these lines should have lower energy usage and enhanced storage density.

  4. Dissociative electron attachment and charge transfer in condensed matter

    International Nuclear Information System (INIS)

    Bass, A.D.; Sanche, L.

    2003-01-01

    Experiments using energy-selected beams of electrons incident from vacuum upon thin vapour deposited solids show that, as in the gas-phase, scattering cross sections at low energies are dominated by the formation of temporary negative ions (or resonances) and that molecular damage may be effected via dissociative electron attachment (DEA). Recent results also show that charge transfer between anionic states of target molecules and their environment is often crucial in determining cross sections for electron driven processes. Here, we review recent work from our laboratory, in which charge transfer is observed. For rare gas solids, electron exchange between the electron-exciton complex and either a metal substrate or co-adsorbed molecule enhances the desorption of metastable atoms and/or molecular dissociation. We discuss how transient electron capture by surface electron states of a substrate and subsequent electron transfer to a molecular adsorbate enhances the effective cross sections for DEA. We also consider the case of DEA to CF 2 Cl 2 condensed on water and ammonia ices, where electron exchange between pre-solvated electron states of ice and transient molecular anions can also increase DEA cross sections. Electron transfer from molecular resonances into pre-solvated electron states of ice is also discussed

  5. Photochemical reactions of electron-deficient olefins with N,N,N',N'-tetramethylbenzidine via photoinduced electron-transfer

    International Nuclear Information System (INIS)

    Pan Yang; Zhao Junshu; Ji Yuanyuan; Yan Lei; Yu Shuqin

    2006-01-01

    Photoinduced electron transfer reactions of several electron-deficient olefins with N,N,N',N'-tetramethylbenzidine (TMB) in acetonitrile solution have been studied by using laser flash photolysis technique and steady-state fluorescence quenching method. Laser pulse excitation of TMB yields 3 TMB* after rapid intersystem crossing from 1 TMB*. The triplet which located at 480 nm is found to undergo fast quenching with the electron acceptors fumaronitrile (FN), dimethyl fumarate (DMF), diethyl fumarate (DEF), cinnamonitrile (CN), α-acetoxyacrylonitrile (AAN), crotononitrile (CrN) and 3-methoxyacrylonitrile (MAN). Substituents binding to olefin molecule own different electron-donating/withdrawing powers, which determine the electron-deficient property (π-cloud density) of olefin molecule as well as control the electron transfer rate constant directly. The detection of ion radical intermediates in the photolysis reactions confirms the proposed electron transfer mechanism, as expected from thermodynamics. The quenching rate constants of triplet TMB by these olefins have been determined at 510 nm to avoid the disturbance of formed TMB cation radical around 475 nm. All the k q T values approach or reach to the diffusion-controlled limit. In addition, fluorescence quenching rate constants k q S have been also obtained by calculating with Stern-Volmer equation. A correlation between experimental electron transfer rate constants and free energy changes has been explained by Marcus theory of adiabatic outer-sphere electron transfer. Disharmonic k q values for CN and CrN in endergonic region may be the disturbance of exciplexs formation. e of exciplex formation

  6. Electron transfer and decay processes of highly charged iodine ions

    International Nuclear Information System (INIS)

    Sakaue, Hiroyuki A.; Danjo, Atsunori; Hosaka, Kazumoto

    2005-01-01

    In the present experimental work we have investigated multi-electron transfer processes in I q+ (q=10, 15, 20 and 25) + Ne, Ar, Kr and Xe collisions at 1.5q keV energy. The branching ratios between Auger and radiative decay channels have been measured in decay processes of multiply excited states formed by multi-electron transfer collisions. It has been shown that, in all the multi-electron transfer processes investigated, the Auger decays are far dominant over the radiative decay processes and the branching ratios are clearly characterized by the average principal quantum number of the initial excited states of projectile ions. We could express the branching ratios in high Rydberg states formed in multi-electron transfer processes by using the decay probability of one Auger electron emission. (author)

  7. Photoinduced electron transfer between benzyloxy dendrimer phthalocyanine and benzoquinone

    Science.gov (United States)

    Zhang, Tiantian; Ma, Dongdong; Pan, Sujuan; Wu, Shijun; Jiang, Yufeng; Zeng, Di; Yang, Hongqin; Peng, Yiru

    2016-10-01

    Photo-induced electron transfer (PET) is an important and fundamental process in natural photosynthesis. To mimic such interesting PET process, a suitable donor and acceptor couple were properly chosen. Dendrimer phthalocyanines and their derivatives have emerged as promising materials for artificial photosynthesis systems. In this paper, the electron transfer between the light harvest dendrimer phthalocyanine (donor) and the 1,4-benzoquinone (acceptor) was studied by UV/Vis and fluorescence spectroscopic methods. It was found that fluorescence of phthalocyanine was quenched by benzoquinone (BQ) via excited state electron transfer, from the phthalocyanine to the BQ upon excitation at 610 nm. The Stern-Volmer constant (KSV) of electron transfer was calculated. Our study suggests that this dendritic phthalocyanine is an effective new electron donor and transmission complex and could be used as a potential artificial photosynthesis system.

  8. Calculation of fusion gain in fast ignition with magnetic target by relativistic electrons and protons

    International Nuclear Information System (INIS)

    Parvazian, A.; Javani, A.

    2010-01-01

    Fast ignition is a new method for inertial confinement fusion in which the compression and ignition steps are separated. In the first stage, fuel is compressed by laser or ion beams. In the second phase, relativistic electrons are generated by pettawat laser in the fuel. Also, in the second phase 5-35 MeV protons can be generated in the fuel. Electrons or protons can penetrate in to the ultra-dense fuel and deposit their energy in the fuel. More recently, cylindrical rather than spherical fuel chambers with magnetic control in the plasma domain have been also considered. This is called magnetized target fusion. Magnetic field has effects on relativistic electrons energy deposition rate in fuel. In this work, fast ignition method in cylindrical fuel chambers is investigated and transportation of the relativistic electrons and protons is calculated using MCNPX and FLUKA codes with 0.25 and 0.5 tesla magnetic field in single and dual hot spot. Furthermore, the transfer rate of relativistic electrons and high energy protons to the fuel and fusion gain are calculated. The results show that the presence of external magnetic field guarantees higher fusion gain, and relativistic electrons are much more appropriate objects for ignition. Magnetized target fusion in dual hot spot can be considered as an appropriate substitution for the current inertial confinement fusion techniques.

  9. Calculation of fusion gain in fast ignition with magnetic target by relativistic electrons and protons

    Directory of Open Access Journals (Sweden)

    A Parvazian

    2010-12-01

    Full Text Available Fast ignition is a new method for inertial confinement fusion (ICF in which the compression and ignition steps are separated. In the first stage, fuel is compressed by laser or ion beams. In the second phase, relativistic electrons are generated by pettawat laser in the fuel. Also, in the second phase 5-35 MeV protons can be generated in the fuel. Electrons or protons can penetrate in to the ultra-dense fuel and deposit their energy in the fuel . More recently, cylindrical rather than spherical fuel chambers with magnetic control in the plasma domain have been also considered. This is called magnetized target fusion (MTF. Magnetic field has effects on relativistic electrons energy deposition rate in fuel. In this work, fast ignition method in cylindrical fuel chambers is investigated and transportation of the relativistic electrons and protons is calculated using MCNPX and FLUKA codes with 0. 25 and 0. 5 tesla magnetic field in single and dual hot spot. Furthermore, the transfer rate of relativistic electrons and high energy protons to the fuel and fusion gain are calculated. The results show that the presence of external magnetic field guarantees higher fusion gain, and relativistic electrons are much more appropriate objects for ignition. MTF in dual hot spot can be considered as an appropriate substitution for the current ICF techniques.

  10. Fast Advection of Magnetic Fields by Hot Electrons

    International Nuclear Information System (INIS)

    Willingale, L.; Thomas, A. G. R.; Krushelnick, K.; Nilson, P. M.; Kaluza, M. C.; Dangor, A. E.; Evans, R. G.; Fernandes, P.; Haines, M. G.; Kamperidis, C.; Kingham, R. J.; Ridgers, C. P.; Sherlock, M.; Wei, M. S.; Najmudin, Z.; Bandyopadhyay, S.; Notley, M.; Minardi, S.; Tatarakis, M.; Rozmus, W.

    2010-01-01

    Experiments where a laser-generated proton beam is used to probe the megagauss strength self-generated magnetic fields from a nanosecond laser interaction with an aluminum target are presented. At intensities of 10 15 W cm -2 and under conditions of significant fast electron production and strong heat fluxes, the electron mean-free-path is long compared with the temperature gradient scale length and hence nonlocal transport is important for the dynamics of the magnetic field in the plasma. The hot electron flux transports self-generated magnetic fields away from the focal region through the Nernst effect [A. Nishiguchi et al., Phys. Rev. Lett. 53, 262 (1984)] at significantly higher velocities than the fluid velocity. Two-dimensional implicit Vlasov-Fokker-Planck modeling shows that the Nernst effect allows advection and self-generation transports magnetic fields at significantly faster than the ion fluid velocity, v N /c s ≅10.

  11. Quantum-Sequencing: Fast electronic single DNA molecule sequencing

    Science.gov (United States)

    Casamada Ribot, Josep; Chatterjee, Anushree; Nagpal, Prashant

    2014-03-01

    A major goal of third-generation sequencing technologies is to develop a fast, reliable, enzyme-free, high-throughput and cost-effective, single-molecule sequencing method. Here, we present the first demonstration of unique ``electronic fingerprint'' of all nucleotides (A, G, T, C), with single-molecule DNA sequencing, using Quantum-tunneling Sequencing (Q-Seq) at room temperature. We show that the electronic state of the nucleobases shift depending on the pH, with most distinct states identified at acidic pH. We also demonstrate identification of single nucleotide modifications (methylation here). Using these unique electronic fingerprints (or tunneling data), we report a partial sequence of beta lactamase (bla) gene, which encodes resistance to beta-lactam antibiotics, with over 95% success rate. These results highlight the potential of Q-Seq as a robust technique for next-generation sequencing.

  12. Electron capture by fast protons from helium-like ions

    International Nuclear Information System (INIS)

    Samanta, R.; Purkait, M.

    2011-01-01

    Four-body formalism of boundary corrected continuum intermediate state (BCCIS-4B) approximation have been applied to calculate the single-electron capture cross sections by fast protons through some helium-like ions in a large energy range from 30-1000 keV. In this model, distortion has been taken into account in the entrance channel. In the final channel, the passive electron plays the role of screening of the target ion. However, continuum states of the projectile and the electron in the field of the residual target ion are included. The comparison of the results is made with those of other theoretical investigations and experimental findings. The present calculated results are found to be in good agreement with the available experimental findings. (authors)

  13. Progress in Fast Ignition Studies with Electrons and Protons

    Science.gov (United States)

    MacKinnon, A. J.; Akli, K. U.; Bartal, T.; Beg, F. N.; Chawla, S.; Chen, C. D.; Chen, H.; Chen, S.; Chowdhury, E.; Fedosejevs, R.; Freeman, R. R.; Hey, D.; Higginson, D.; Key, M. H.; King, J. A.; Link, A.; Ma, T.; MacPhee, A. G.; Offermann, D.; Ovchinnikov, V.; Pasley, J.; Patel, P. K.; Ping, Y.; Schumacher, D. W.; Stephens, R. B.; Tsui, Y. Y.; Wei, M. S.; Van Woerkom, L. D.

    2009-09-01

    Isochoric heating of inertially confined fusion plasmas by laser driven MeV electrons or protons is an area of great topical interest in the inertial confinement fusion community, particularly with respect to the fast ignition (FI) concept for initiating burn in a fusion capsule. In order to investigate critical aspects needed for a FI point design, experiments were performed to study 1) laser-to-electrons or protons conversion issues and 2) laser-cone interactions including prepulse effects. A large suite of diagnostics was utilized to study these important parameters. Using cone—wire surrogate targets it is found that pre-pulse levels on medium scale lasers such as Titan at Lawrence Livermore National Laboratory produce long scale length plasmas that strongly effect coupling of the laser to FI relevant electrons inside cones. The cone wall thickness also affects coupling to the wire. Conversion efficiency to protons has also been measured and modeled as a function of target thickness, material. Conclusions from the proton and electron source experiments will be presented. Recent advances in modeling electron transport and innovative target designs for reducing igniter energy and increasing gain curves will also be discussed. In conclusion, a program of study will be presented based on understanding the fundamental physics of the electron or proton source relevant to FI.

  14. Extracellular electron transfer mechanisms between microorganisms and minerals

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Liang; Dong, Hailiang; Reguera, Gemma; Beyenal, Haluk; Lu, Anhuai; Liu, Juan; Yu, Han-Qing; Fredrickson, James K.

    2016-08-30

    Electrons can be transferred from microorganisms to multivalent metal ions that are associated with minerals and vice versa. As the microbial cell envelope is neither physically permeable to minerals nor electrically conductive, microorganisms have evolved strategies to exchange electrons with extracellular minerals. In this Review, we discuss the molecular mechanisms that underlie the ability of microorganisms to exchange electrons, such as c-type cytochromes and microbial nanowires, with extracellular minerals and with microorganisms of the same or different species. Microorganisms that have extracellular electron transfer capability can be used for biotechnological applications, including bioremediation, biomining and the production of biofuels and nanomaterials.

  15. Photoinduced electron transfer in some photosensitive molecules ...

    Indian Academy of Sciences (India)

    Unknown

    redox reactions of substrates like biological molecules,11,12 dyes,13,14 alcohols15,16 etc. Colloidal ... state which is characterised by a phenomenon of dual fluorescence. In the present ... The dried solid was transferred to quartz cell under vacuum ... Recently Grätzel et al34 have developed the dye-sensitized meso-.

  16. Theoretical aspects of electron transfer reactions of complex molecules

    DEFF Research Database (Denmark)

    Kuznetsov, A. M.; Ulstrup, Jens

    2001-01-01

    Features of electron transfer involving complex molecules are discussed. This notion presently refers to molecular reactants where charge transfer is accompanied by large molecular reorganization, and commonly used displaced harmonic oscillator models do not apply. It is shown that comprehensive...... theory of charge transfer in polar media offers convenient tools for the treatment of experimental data for such systems, with due account of large-amplitude strongly anharmonic intramolecular reorganization. Equations for the activation barrier and free energy relationships are provided, incorporating...

  17. Fast and simple model for atmospheric radiative transfer

    NARCIS (Netherlands)

    Seidel, F.C.; Kokhanovsky, A.A.; Schaepman, M.E.

    2010-01-01

    Radiative transfer models (RTMs) are of utmost importance for quantitative remote sensing, especially for compensating atmospheric perturbation. A persistent trade-off exists between approaches that prefer accuracy at the cost of computational complexity, versus those favouring simplicity at the

  18. Stark-like electron transfer between quantum wells

    International Nuclear Information System (INIS)

    Dubovis, S.A.; Voronko, A.N.; Basharov, A.M.

    2008-01-01

    The Stark-like mechanism of electron transfer between two energy subband localized in remote quantum wells is examined theoretically. Estimations of major parameters of the problem in case of delta-function-wells model are adduced. Schematic model allowing experimental study of Stark-like transfer is proposed

  19. Distorted wave calculations for double electron transfer

    International Nuclear Information System (INIS)

    Martinez, A.E.; Rivarola, R.D.; Gayet, R.; Hanssen, J.

    1992-01-01

    The resonant double electron capture by alpha particles in helium targets is studied, at intermediate and high collision energies, using the Continuum Distorted Wave - Eikonal Initial State (CDW-EIS) model. Differential and total cross sections for capture into the He (1 s 2 ) final state are calculated in the framework of an Independent Electron Approximation (IEA). Theoretical results are compared with the experimental data available at present for capture into any final state of helium. (author)

  20. Laser pulse control of bridge mediated heterogeneous electron transfer

    International Nuclear Information System (INIS)

    Wang Luxia; May, Volkhard

    2009-01-01

    Ultrafast heterogeneous electron transfer from surface attached dye molecules into semiconductor band states is analyzed. The focus is on systems where the dye is separated from the surface by different bridge anchor groups. To simulate the full quantum dynamics of the transfer process a model of reduced dimensionality is used. It comprises the electronic levels of the dye, the bridge anchor group electronic levels and the continuum of semiconductor band states, all defined versus a single intramolecular vibrational coordinate. The effect of the bridge states is demonstrated, firstly, in studying the injection dynamics following an impulsive excitation of the dye. Then, by discussing different control tasks it is demonstrate in which way the charge injection process can be influenced by tailored laser pulses. To highlight the importance of electron wave function interference emphasis is put on asymmetric two-bridge molecule systems which are also characterized by different and complex valued electronic transfer matrix elements.

  1. Computational Approach to Electron Charge Transfer Reactions

    DEFF Research Database (Denmark)

    Jónsson, Elvar Örn

    -molecular mechanics scheme, and tools to analyse statistical data and generate relative free energies and free energy surfaces. The methodology is applied to several charge transfer species and reactions in chemical environments - chemical in the sense that solvent, counter ions and substrate surfaces are taken...... in to account - which directly influence the reactants and resulting reaction through both physical and chemical interactions. All methods are though general and can be applied to different types of chemistry. First, the basis of the various theoretical tools is presented and applied to several test systems...... and asymmetric charge transfer reactions between several first-row transition metals in water. The results are compared to experiments and rationalised with classical analytic expressions. Shortcomings of the methods are accounted for with clear steps towards improved accuracy. Later the analysis is extended...

  2. Effect of electron degeneracy on fast-particles energy deposition in dense plasma systems

    International Nuclear Information System (INIS)

    Johzaki, T.; Nakao, Y.; Nakashima, H.; Kudo, K.

    1997-01-01

    The effects of electron degeneracy on fast-particles energy deposition in dense plasmas are investigated by making transport calculations for the fast particles. It is found that the degeneracy substantially affects the profiles of energy deposition of 3.52-MeV α-particles. On the other hand, the effect on the energy deposition of 14.1-MeV neutrons is negligibly small because the recoil ions, which transfer the neutron energy to the plasma constituents, are produced in a whole plasma volume due to the long mean-free-path of neutrons. The coupled transport-hydrodynamic calculations show that these effects of degeneracy are negligible in the ignition and burn characteristics of central ignition D-T targets. (author)

  3. Indoor Fast Neutron Generator for Biophysical and Electronic Applications

    Science.gov (United States)

    Cannuli, A.; Caccamo, M. T.; Marchese, N.; Tomarchio, E. A.; Pace, C.; Magazù, S.

    2018-05-01

    This study focuses the attention on an indoor fast neutron generator for biophysical and electronic applications. More specifically, the findings obtained by several simulations with the MCNP Monte Carlo code, necessary for the realization of a shield for indoor measurements, are presented. Furthermore, an evaluation of the neutron spectrum modification caused by the shielding is reported. Fast neutron generators are a valid and interesting available source of neutrons, increasingly employed in a wide range of research fields, such as science and engineering. The employed portable pulsed neutron source is a MP320 Thermo Scientific neutron generator, able to generate 2.5 MeV neutrons with a neutron yield of 2.0 x 106 n/s, a pulse rate of 250 Hz to 20 KHz and a duty factor varying from 5% to 100%. The neutron generator, based on Deuterium-Deuterium nuclear fusion reactions, is employed in conjunction with a solid-state photon detector, made of n-type high-purity germanium (PINS-GMX by ORTEC) and it is mainly addressed to biophysical and electronic studies. The present study showed a proposal for the realization of a shield necessary for indoor applications for MP320 neutron generator, with a particular analysis of the transport of neutrons simulated with Monte Carlo code and described the two main lines of research in which the source will be used.

  4. Fast electronic structure methods for strongly correlated molecular systems

    International Nuclear Information System (INIS)

    Head-Gordon, Martin; Beran, Gregory J O; Sodt, Alex; Jung, Yousung

    2005-01-01

    A short review is given of newly developed fast electronic structure methods that are designed to treat molecular systems with strong electron correlations, such as diradicaloid molecules, for which standard electronic structure methods such as density functional theory are inadequate. These new local correlation methods are based on coupled cluster theory within a perfect pairing active space, containing either a linear or quadratic number of pair correlation amplitudes, to yield the perfect pairing (PP) and imperfect pairing (IP) models. This reduces the scaling of the coupled cluster iterations to no worse than cubic, relative to the sixth power dependence of the usual (untruncated) coupled cluster doubles model. A second order perturbation correction, PP(2), to treat the neglected (weaker) correlations is formulated for the PP model. To ensure minimal prefactors, in addition to favorable size-scaling, highly efficient implementations of PP, IP and PP(2) have been completed, using auxiliary basis expansions. This yields speedups of almost an order of magnitude over the best alternatives using 4-center 2-electron integrals. A short discussion of the scope of accessible chemical applications is given

  5. Electron transfer reactions in microporous solids

    Energy Technology Data Exchange (ETDEWEB)

    Mallouk, T.E.

    1993-01-01

    Basic thrust the research program involves use of microporous solids (zeolites, clays, layered and tunnel structure oxide semiconductors) as organizing media for artificial photosynthetic systems. Purpose of the microporous solid is twofold. First, it induces spatial organization of photoactive and electroactive components (sensitizers, semiconductor particles, electron relays, and catalysts) at the solid-solution interface, enhancing the quantum efficiency of charge separation and separating physically the ultimate electron donor and acceptor in the electron transport chain. Second, since the microcrystalline solid admits only molecules of a certain charge and size, it is possible to achieve permanent charge separation by sieving chemical photoproducts (e.g., H[sub 2] and I[sub 3][sup [minus

  6. Studies on electron transfer reactions of Keggin-type mixed ...

    Indian Academy of Sciences (India)

    Administrator

    (PV2) in aqueous phosphate buffer of pH 6 at ambient temperature. Electrochemical and optical studies show that the stoichiometry of the reaction is 1: 2 (NADH : HPA). EPR and optical studies show that HPA act as one electron acceptor and the products of electron transfer reactions are one elec- tron reduced heteropoly ...

  7. Quantum electron transfer processes induced by thermo-coherent ...

    Indian Academy of Sciences (India)

    WINTEC

    Thermo-coherent state; electron transfer; quantum rate. 1. Introduction. The study ... two surfaces,16 namely, one electron two-centered exchange problem,7–10 many ... temperature classical regime for the single and the two-mode cases have ...

  8. Fast electrons from multi-electron dynamics in xenon clusters induced by inner-shell ionization

    International Nuclear Information System (INIS)

    Bostedt, Christoph; Thomas, Heiko; Hoener, Matthias; Moeller, Thomas; Saalmann, Ulf; Georgescu, Ionut; Gnodtke, Christian; Rost, Jan-Michael

    2010-01-01

    Fast electrons emitted from xenon clusters in strong femtosecond 90 eV pulses have been measured at the Free-electron Laser in Hamburg (FLASH). Energy absorption occurs mainly through atomic inner-shell photo-ionization. Photo-electrons are trapped in the strong Coulomb potential of the cluster ions and form a non-equilibrium plasma with supra-atomic density. Its equilibration through multiple energy-exchanging collisions within the entire cluster volume produces electrons with energies well beyond the dominant emission line of atomic xenon. Here, in contrast to traditional low-frequency laser plasma heating, the plasma gains energy from electrons delivered through massive single-photon excitation from bound states. Electron emission induced by thermalization of a non-equilibrium plasma is expected to be a general phenomenon occurring for strong atomic x-ray absorption in extended systems.

  9. Toddlers' word learning and transfer from electronic and print books.

    Science.gov (United States)

    Strouse, Gabrielle A; Ganea, Patricia A

    2017-04-01

    Transfer from symbolic media to the real world can be difficult for young children. A sample of 73 toddlers aged 17 to 23months were read either an electronic book displayed on a touchscreen device or a traditional print book in which a novel object was paired with a novel label. Toddlers in both conditions learned the label within the context of the book. However, only those who read the traditional format book generalized and transferred the label to other contexts. An older group of 28 toddlers aged 24 to 30months did generalize and transfer from the electronic book. Across ages, those children who primarily used screens to watch prerecorded video at home transferred less from the electronic book than those with more diverse home media experiences. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Heat transfer between adsorbate and laser-heated hot electrons

    International Nuclear Information System (INIS)

    Ueba, H; Persson, B N J

    2008-01-01

    Strong short laser pulses can give rise to a strong increase in the electronic temperature at metal surfaces. Energy transfer from the hot electrons to adsorbed molecules may result in adsorbate reactions, e.g. desorption or diffusion. We point out the limitations of an often used equation to describe the heat transfer process in terms of a friction coupling. We propose a simple theory for the energy transfer between the adsorbate and hot electrons using a newly introduced heat transfer coefficient, which depends on the adsorbate temperature. We calculate the transient adsorbate temperature and the reaction yield for a Morse potential as a function of the laser fluency. The results are compared to those obtained using a conventional heat transfer equation with temperature-independent friction. It is found that our equation of energy (heat) transfer gives a significantly lower adsorbate peak temperature, which results in a large modification of the reaction yield. We also consider the heat transfer between different vibrational modes excited by hot electrons. This mode coupling provides indirect heating of the vibrational temperature in addition to the direct heating by hot electrons. The formula of heat transfer through linear mode-mode coupling of two harmonic oscillators is applied to the recent time-resolved study of carbon monoxide and atomic oxygen hopping on an ultrafast laser-heated Pt(111) surface. It is found that the maximum temperature of the frustrated translation mode can reach high temperatures for hopping, even when direct friction coupling to the hot electrons is not strong enough

  11. Electron transfer, ionization, and excitation atomic collisions

    International Nuclear Information System (INIS)

    Winter, T.G.; Alston, S.G.

    1990-01-01

    Basic atomic-collision processes at intermediate and high energies are being studied theoretically at Penn State by Alston and Winter. In the high velocity regime, single-electron capture is treated using a high order multiple-scattering approach; extensive comparison with experiment and analysis of mechanisms have been made. Fitting the calculated amplitude with a simple analytic form, the asymptotic velocity dependence of the cross section is obtained. The effect on the capture amplitude of altering the inner part of the internuclear potential has also been explored. In the intermediate velocity regime, earlier work on collisions between protons and hydrogenic-ion targets using a coupled-state approach is being extended to the two-electron helium target. 29 refs

  12. Electronic Energy Transfer in Polarizable Heterogeneous Environments

    DEFF Research Database (Denmark)

    Svendsen, Casper Steinmann; Kongsted, Jacob

    2015-01-01

    such couplings provide important insight into the strength of interaction between photo-active pigments in protein-pigment complexes. Recently, attention has been payed to how the environment modifies or even controls the electronic couplings. To enable such theoretical predictions, a fully polarizable embedding......-order multipole moments. We use this extended model to systematically examine three different ways of obtaining EET couplings in a heterogeneous medium ranging from use of the exact transition density to a point-dipole approximation. Several interesting observations are made including that explicit use...... of transition densities in the calculation of the electronic couplings - also when including the explicit environment contribution - can be replaced by a much simpler transition point charge description without comprising the quality of the model predictions....

  13. Monitoring sequential electron transfer with EPR

    International Nuclear Information System (INIS)

    Thurnauer, M.C.; Feezel, L.L.; Snyder, S.W.; Tang, J.; Norris, J.R.; Morris, A.L.; Rustandi, R.R.

    1989-01-01

    A completely general model which treats electron spin polarization (ESP) found in a system in which radical pairs with different magnetic interactions are formed sequentially has been described. This treatment has been applied specifically to the ESP found in the bacterial reaction center. Test cases show clearly how parameters such as structure, lifetime, and magnetic interactions within the successive radical pairs affect the ESP, and demonstrate that previous treatments of this problem have been incomplete. The photosynthetic bacterial reaction center protein is an ideal system for testing the general model of ESP. The radical pair which exhibits ESP, P 870 + Q - (P 870 + is the oxidized, primary electron donor, a bacteriochlorophyll special pair and Q - is the reduced, primary quinone acceptor) is formed via sequential electron transport through the intermediary radical pair P 870 + I - (I - is the reduced, intermediary electron acceptor, a bacteriopheophytin). In addition, it is possible to experimentally vary most of the important parameters, such as the lifetime of the intermediary radical pair and the magnetic interactions in each pair. It has been shown how selective isotopic substitution ( 1 H or 2 H) on P 870 , I and Q affects the ESP of the EPR spectrum of P 870 + Q - , observed at two different microwave frequencies, in Fe 2+ -depleted bacterial reaction centers of Rhodobacter sphaeroides R26. Thus, the relative magnitudes of the magnetic properties (nuclear hyperfine and g-factor differences) which influence ESP development were varied. The results support the general model of ESP in that they suggest that the P 870 + Q - radical pair interactions are the dominant source of ESP production in 2 H bacterial reaction centers

  14. Fast & scalable pattern transfer via block copolymer nanolithography

    DEFF Research Database (Denmark)

    Li, Tao; Wang, Zhongli; Schulte, Lars

    2015-01-01

    A fully scalable and efficient pattern transfer process based on block copolymer (BCP) self-assembling directly on various substrates is demonstrated. PS-rich and PDMS-rich poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) copolymers are used to give monolayer sphere morphology after spin-casting of s......A fully scalable and efficient pattern transfer process based on block copolymer (BCP) self-assembling directly on various substrates is demonstrated. PS-rich and PDMS-rich poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) copolymers are used to give monolayer sphere morphology after spin...... on long range lateral order, including fabrication of substrates for catalysis, solar cells, sensors, ultrafiltration membranes and templating of semiconductors or metals....

  15. Proton-coupled electron transfer versus hydrogen atom transfer: generation of charge-localized diabatic states.

    Science.gov (United States)

    Sirjoosingh, Andrew; Hammes-Schiffer, Sharon

    2011-03-24

    The distinction between proton-coupled electron transfer (PCET) and hydrogen atom transfer (HAT) mechanisms is important for the characterization of many chemical and biological processes. PCET and HAT mechanisms can be differentiated in terms of electronically nonadiabatic and adiabatic proton transfer, respectively. In this paper, quantitative diagnostics to evaluate the degree of electron-proton nonadiabaticity are presented. Moreover, the connection between the degree of electron-proton nonadiabaticity and the physical characteristics distinguishing PCET from HAT, namely, the extent of electronic charge redistribution, is clarified. In addition, a rigorous diabatization scheme for transforming the adiabatic electronic states into charge-localized diabatic states for PCET reactions is presented. These diabatic states are constructed to ensure that the first-order nonadiabatic couplings with respect to the one-dimensional transferring hydrogen coordinate vanish exactly. Application of these approaches to the phenoxyl-phenol and benzyl-toluene systems characterizes the former as PCET and the latter as HAT. The diabatic states generated for the phenoxyl-phenol system possess physically meaningful, localized electronic charge distributions that are relatively invariant along the hydrogen coordinate. These diabatic electronic states can be combined with the associated proton vibrational states to generate the reactant and product electron-proton vibronic states that form the basis of nonadiabatic PCET theories. Furthermore, these vibronic states and the corresponding vibronic couplings may be used to calculate rate constants and kinetic isotope effects of PCET reactions.

  16. Effect of proton transfer on the electronic coupling in DNA

    International Nuclear Information System (INIS)

    Rak, Janusz; Makowska, Joanna; Voityuk, Alexander A.

    2006-01-01

    The effects of single and double proton transfer within Watson-Crick base pairs on donor-acceptor electronic couplings, V da , in DNA are studied on the bases of quantum chemical calculations. Four dimers [AT,AT], [GC,GC], [GC,AT] and [GC,TA)] are considered. Three techniques - the generalized Mulliken-Hush scheme, the fragment charge method and the diabatic states method - are employed to estimate V da for hole transfer between base pairs. We show that both single- and double proton transfer (PT) reactions may substantially affect the electronic coupling in DNA. The electronic coupling in [AT,AT] is predicted to be most sensitive to PT. Single PT within the first base pair in the dimer leads to increase in the hole transfer efficiency by a factor of 4, while proton transfer within the second pair should substantially, by 2.7 times, decrease the rate of charge transfer. Thus, directional asymmetry of the PT effects on the electronic coupling is predicted. The changes in the V da matrix elements correlate with the topological properties of orbitals of donor and acceptor and can be qualitatively rationalized in terms of resonance structures of donor and acceptor. Atomic pair contributions to the V da matrix elements are also analyzed

  17. Nanosecond-timescale spin transfer using individual electrons in a quadruple-quantum-dot device

    Energy Technology Data Exchange (ETDEWEB)

    Baart, T. A.; Jovanovic, N.; Vandersypen, L. M. K. [QuTech and Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft (Netherlands); Reichl, C.; Wegscheider, W. [Solid State Physics Laboratory, ETH Zürich, 8093 Zürich (Switzerland)

    2016-07-25

    The ability to coherently transport electron-spin states between different sites of gate-defined semiconductor quantum dots is an essential ingredient for a quantum-dot-based quantum computer. Previous shuttles using electrostatic gating were too slow to move an electron within the spin dephasing time across an array. Here, we report a nanosecond-timescale spin transfer of individual electrons across a quadruple-quantum-dot device. Utilizing enhanced relaxation rates at a so-called hot spot, we can upper bound the shuttle time to at most 150 ns. While actual shuttle times are likely shorter, 150 ns is already fast enough to preserve spin coherence in, e.g., silicon based quantum dots. This work therefore realizes an important prerequisite for coherent spin transfer in quantum dot arrays.

  18. [Electron transfer, ionization, and excitation in atomic collisions

    International Nuclear Information System (INIS)

    1992-01-01

    Fundamental processes of electron transfer, ionization, and excitation in ion-atom and ion-ion collisions are studied. Attention is focussed on one- and two-electron systems and, more recently, quasi-one-electron systems whose electron-target-ion core can be accurately modeled by one-electron potentials. The basic computational approaches can then be taken with few, if any, approximations, and the underlying collisional mechanisms can be more clearly revealed. At intermediate collision energies (e.g., proton energies for p-He + collisions on the order of 100 kilo-electron volts), many electronic states are strongly coupled during the collision, a coupled-state approach, such as a coupled-Sturmian-pseudostate approach, is appropriate. At higher collision energies (million electron-volt energies) the coupling is weaker with, however, many more states being coupled together, so that high-order perturbation theory is essential

  19. Study of electron and proton isochoric heating for fast ignition

    International Nuclear Information System (INIS)

    Key, M.H.; Chen, M.H.; Chung, H.K.; Foord, M.E.; Gregori, G.; Hatchett, S.P.; Koch, J.A.; Lasinski, B.F.; Langdon, B.; MacKinnon, A.J.; Patel, P.; Snavely, R.A.; Tabak, M.; Town, R.; Wilks, S.C.; Akli, K.; Freeman, R.R.; Gu, P.; Hey, D.; Hill, J.M.; King, J.A.; Patel, N.; Zhang, B.; Freeman, R.R.; Stephens, R.B.; Beg, F.; Pasley, J.; Green, J.S.; Lancaster, K.; Murphy, C.D.; Norreys, P.A.; Green, J.S.; Murphy, C.D.; Habara, H.; Kodama, R.; Tanaka, K.; Yabuuchi, T.; Stoeckl, C.; Theobald, W.

    2006-01-01

    Isochoric heating by electrons has been measured in the two limiting cases of small area thin foils with dominant refluxing and cone-long-wire geometry with negligible refluxing in the wire. Imaging of Cu Kα cone fluorescence, crystal X-ray spectroscopy of Cu K shell emission, and X UV imaging at 68 eV and 256 eV are discussed. Laser power on target was typically 0.5 PW in 0.7 ps. Heating by focused proton beams generated at the concave inside surface of a hemi-shell and from a sub hemi-shell inside 30 degrees cone has been studied with the same diagnostic methods plus imaging of proton induced Kα. Conversion efficiency to protons has been measured and modeled. Conclusions from the experiments, links to theoretical understanding and relevance to fast ignition are outlined. (authors)

  20. Fast sub-electron detectors review for interferometry

    Science.gov (United States)

    Feautrier, Philippe; Gach, Jean-Luc; Bério, Philippe

    2016-08-01

    New disruptive technologies are now emerging for detectors dedicated to interferometry. The detectors needed for this kind of applications need antonymic characteristics: the detector noise must be very low, especially when the signal is dispersed but at the same time must also sample the fast temporal characteristics of the signal. This paper describes the new fast low noise technologies that have been recently developed for interferometry and adaptive optics. The first technology is the Avalanche PhotoDiode (APD) infrared arrays made of HgCdTe. In this paper are presented the two programs that have been developed in that field: the Selex Saphira 320x256 [1] and the 320x255 RAPID detectors developed by Sofradir/CEA LETI in France [2], [3], [4]. Status of these two programs and future developments are presented. Sub-electron noise can now be achieved in the infrared using this technology. The exceptional characteristics of HgCdTe APDs are due to a nearly exclusive impaction ionization of the electrons, and this is why these devices have been called "electrons avalanche photodiodes" or e-APDs. These characteristics have inspired a large effort in developing focal plan arrays using HgCdTe APDs for low photon number applications such as active imaging in gated mode (2D) and/or with direct time of flight detection (3D imaging) and, more recently, passive imaging for infrared wave front correction and fringe tracking in astronomical observations. In addition, a commercial camera solution called C-RED, based on Selex Saphira and commercialized by First Light Imaging [5], is presented here. Some groups are also working with instruments in the visible. In that case, another disruptive technology is showing outstanding performances: the Electron Multiplying CCDs (EMCCD) developed mainly by e2v technologies in UK. The OCAM2 camera, commercialized by First Light Imaging [5], uses the 240x240 EMMCD from e2v and is successfully implemented on the VEGA instrument on the CHARA

  1. Helquats, helical extended diquats, as fast electron transfer systems

    Czech Academy of Sciences Publication Activity Database

    Pospíšil, Lubomír; Teplý, Filip; Gál, Miroslav; Adriaenssens, Louis; Horáček, Michal; Severa, Lukáš

    2010-01-01

    Roč. 12, č. 7 (2010), s. 1550-1556 ISSN 1463-9076 R&D Projects: GA ČR GA203/09/0705; GA ČR GP203/09/P502; GA MŠk ME09114; GA MŠk OC 140 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40550506 Keywords : reversible redox systems * self-exchange kinetics * methyl viologen Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.454, year: 2010

  2. Fast-electron self-collimation in a plasma density gradient

    International Nuclear Information System (INIS)

    Yang, X. H.; Borghesi, M.; Robinson, A. P. L.

    2012-01-01

    A theoretical and numerical study of fast electron transport in solid and compressed fast ignition relevant targets is presented. The principal aim of the study is to assess how localized increases in the target density (e.g., by engineering of the density profile) can enhance magnetic field generation and thus pinching of the fast electron beam through reducing the rate of temperature rise. The extent to which this might benefit fast ignition is discussed.

  3. Intramolecular electron transfer in single-site-mutated azurins

    DEFF Research Database (Denmark)

    Farver, O; Skov, L K; Pascher, T

    1993-01-01

    . Natl. Acad. Sci. U.S.A. 86, 6968-6972]. The RSSR- radical produced in the above reaction was reoxidized in a slower intramolecular electron-transfer process (30-70 s-1 at 298 K) concomitant with a further reduction of the Cu(II) ion. The temperature dependence of the latter rates was determined......, lambda = 135 kJ mol-1 for the reorganization energy was derived. When Trp48, situated midway between the donor and the acceptor, was replaced by Leu or Met, only a small change in the rate of intramolecular electron transfer was observed, indicating that the aromatic residue in this position...... is apparently only marginally involved in electron transfer in wild-type azurin. Pathway calculations also suggest that a longer, through-backbone path is more efficient than the shorter one involving Trp48. The former pathway yields an exponential decay factor, beta, of 6.6 nm-1. Another mutation, raising...

  4. Electron transfer dynamics: Zusman equation versus exact theory

    International Nuclear Information System (INIS)

    Shi Qiang; Chen Liping; Nan Guangjun; Xu Ruixue; Yan Yijing

    2009-01-01

    The Zusman equation has been widely used to study the effect of solvent dynamics on electron transfer reactions. However, application of this equation is limited by the classical treatment of the nuclear degrees of freedom. In this paper, we revisit the Zusman equation in the framework of the exact hierarchical equations of motion formalism, and show that a high temperature approximation of the hierarchical theory is equivalent to the Zusman equation in describing electron transfer dynamics. Thus the exact hierarchical formalism naturally extends the Zusman equation to include quantum nuclear dynamics at low temperatures. This new finding has also inspired us to rescale the original hierarchical equations and incorporate a filtering algorithm to efficiently propagate the hierarchical equations. Numerical exact results are also presented for the electron transfer reaction dynamics and rate constant calculations.

  5. Screening of exciplex formation by distant electron transfer.

    Science.gov (United States)

    Fedorenko, S G; Khokhlova, S S; Burshtein, A I

    2012-01-12

    The excitation quenching by reversible exciplex formation, combined with irreversible but distant electron transfer, is considered by means of the integral encounter theory (IET). Assuming that the quenchers are in great excess, the set of IET equations for the excitations, free ions, and exciplexes is derived. Solving these equations gives the Laplace images of all these populations, and these are used to specify the quantum yields of the corresponding reaction products. It appears that diffusion facilitates the exciplex production and the electron transfer. On the other hand the stronger the electron transfer is, the weaker is the exciplex production. At slow diffusion the distant quenching of excitations by ionization prevents their reaching the contact where they can turn into exciplexes. This is a screening effect that is most pronounced when the ionization rate is large.

  6. Numerical Simulation of Transient Moisture Transfer into an Electronic Enclosure

    DEFF Research Database (Denmark)

    Shojaee Nasirabadi, Parizad; Jabbaribehnam, Mirmasoud; Hattel, Jesper Henri

    2016-01-01

    Electronic systems are sometimes exposed to harsh environmental conditions of temperature and humidity. Moisturetransfer into electronic enclosures and condensation can cause several problems such as corrosion and alteration in thermalstresses. It is therefore essential to study the local climate...... inside the enclosures to be able to protect the electronic systems.In this work, moisture transfer into a typical electronic enclosure is numerically studied using CFD. In order to reduce theCPU-time and make a way for subsequent factorial design analysis, a simplifying modification is applied in which...

  7. Photoinduced bimolecular electron transfer kinetics in small unilamellar vesicles

    International Nuclear Information System (INIS)

    Choudhury, Sharmistha Dutta; Kumbhakar, Manoj; Nath, Sukhendu; Pal, Haridas

    2007-01-01

    Photoinduced electron transfer (ET) from N,N-dimethylaniline to some coumarin derivatives has been studied in small unilamellar vesicles (SUVs) of the phospholipid, DL-α-dimyristoyl-phosphatidylcholine, using steady-state and time-resolved fluorescence quenching, both below and above the phase transition temperature of the vesicles. The primary interest was to examine whether Marcus inversion [H. Sumi and R. A. Marcus, J. Chem. Phys. 84, 4894 (1986)] could be observed for the present ET systems in these organized assemblies. The influence of the topology of SUVs on the photophysical properties of the reactants and consequently on their ET kinetics has also been investigated. Absorption and fluorescence spectral data of the coumarins in SUVs and the variation of their fluorescence decays with temperature indicate that the dyes are localized in the bilayer of the SUVs. Time-resolved area normalized emission spectra analysis, however, reveals that the dyes are distributed in two different microenvironments in the SUVs, which we attribute to the two leaflets of the bilayer, one toward bulk water and the other toward the inner water pool. The microenvironments in the two leaflets are, however, not indicated to be that significantly different. Time-resolved anisotropy decays were biexponential for all the dyes in SUVs, and this has been interpreted in terms of the compound motion model according to which the dye molecules can experience a fast wobbling-in-cone type of motion as well as a slow overall rotating motion of the cone containing the molecule. The expected bimolecular diffusion-controlled rates in SUVs, as estimated by comparing the microviscosities in SUVs (determined from rotational correlation times) and that in acetonitrile solution, are much slower than the observed fluorescence quenching rates, suggesting that reactant diffusion (translational) does not play any role in the quenching kinetics in the present systems. Accordingly, clear inversions are

  8. A modified Fricke gel dosimeter for fast electron blood dosimetry

    International Nuclear Information System (INIS)

    Del Lama, L.S.; Góes, E.G. de; Sampaio, F.G.A.; Petchevist, P.C.D.; Almeida, A. de

    2014-01-01

    It has been suggested for more than forty years that blood and blood components be irradiated before allogeneic transfusions for immunosuppressed patients in order to avoid the Transfusion-Associated Graft-versus-Host Disease (TA-GVHD). Whole blood, red blood cells, platelets and granulocytes may have viable T cells and should be irradiated before transfusion for different patient clinical conditions. According to international guides, absorbed doses from 25 up to 50 Gy should be delivered to the central middle plane of each blood bag. Although gamma and X-rays from radiotherapy equipments and dedicated cell irradiators are commonly used for this purpose, electron beams from Linear Accelerators (LINACs) could be used as well. In this work, we developed a methodology able to acquire dosimetric data from blood irradiations, especially after fast electrons exposures. This was achieved using a proposed Fricke Xylenol Gel (FXG p ) dosimeter, which presents closer radiological characteristics (attenuation coefficients and stopping-powers) to the whole blood, as well as complete absorbed dose range linearity. The developed methodology and the FXG p dosimeter were also able to provide isodose curves and field profiles for the irradiated samples

  9. A modified Fricke gel dosimeter for fast electron blood dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Del Lama, L.S., E-mail: lucasdellama@gmail.com [Departamento de Fsica, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (FFCLRP/USP), Av. Bandeirantes, 3900, CEP 14040-901, Bairro Monte Alegre, Ribeirão Preto, São Paulo (Brazil); Góes, E.G. de [Instituto de Matemática, Estatística e Física, Universidade Federal de Rio Grande (IMEF/FURG), Av. Itália, km 8, CEP 96201-900, Bairro Carreiros, Rio Grande, Rio Grande do Sul (Brazil); Sampaio, F.G.A.; Petchevist, P.C.D.; Almeida, A. de [Departamento de Fsica, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (FFCLRP/USP), Av. Bandeirantes, 3900, CEP 14040-901, Bairro Monte Alegre, Ribeirão Preto, São Paulo (Brazil)

    2014-12-15

    It has been suggested for more than forty years that blood and blood components be irradiated before allogeneic transfusions for immunosuppressed patients in order to avoid the Transfusion-Associated Graft-versus-Host Disease (TA-GVHD). Whole blood, red blood cells, platelets and granulocytes may have viable T cells and should be irradiated before transfusion for different patient clinical conditions. According to international guides, absorbed doses from 25 up to 50 Gy should be delivered to the central middle plane of each blood bag. Although gamma and X-rays from radiotherapy equipments and dedicated cell irradiators are commonly used for this purpose, electron beams from Linear Accelerators (LINACs) could be used as well. In this work, we developed a methodology able to acquire dosimetric data from blood irradiations, especially after fast electrons exposures. This was achieved using a proposed Fricke Xylenol Gel (FXG{sub p}) dosimeter, which presents closer radiological characteristics (attenuation coefficients and stopping-powers) to the whole blood, as well as complete absorbed dose range linearity. The developed methodology and the FXG{sub p} dosimeter were also able to provide isodose curves and field profiles for the irradiated samples.

  10. Study and impact of fast electrons diagnosed by electron cyclotron radiation on Tore-Supra tokamak

    International Nuclear Information System (INIS)

    Gomez, P.

    1999-12-01

    This thesis aims at characterizing the dynamics of fast electrons generated by the Landau absorption of the hybrid wave and studying their effects on electron cyclotron radiation. The different processes involved in the propagation and resonant absorption of the hybrid wave in plasmas are described. A method such as ray-tracing allows the characterization of the dynamics of heating but this method relies on the hypothesis of geometrical optics. Whenever absorption rate is low as it is in Tore-Supra, the hybrid wave undergoes a series of successive reflections on the edge of the plasma before being completely absorbed. These reflections generate an electromagnetic chaos in which geometrical optics hypothesis are no longer valid. A statistical treatment of the Fokker-Planck equation allows the calculation of the mean distribution function of electrons in the plasma submitted to hybrid wave. The electron cyclotron radiation is then deduced and by assuming that plasma behaves like a black body, a theoretical radiative temperature is calculated. The confrontation of this theoretical temperature profile with experimental values allows the validation of this modeling and the estimation of the effects of fast electrons on temperature measurements. (A.C.)

  11. Electron Transfer Strategies Regulate Carbonate Mineral and Micropore Formation.

    Science.gov (United States)

    Zeng, Zhirui; Tice, Michael M

    2018-01-01

    Some microbial carbonates are robust biosignatures due to their distinct morphologies and compositions. However, whether carbonates induced by microbial iron reduction have such features is unknown. Iron-reducing bacteria use various strategies to transfer electrons to iron oxide minerals (e.g., membrane-bound enzymes, soluble electron shuttles, nanowires, as well as different mechanisms for moving over or attaching to mineral surfaces). This diversity has the potential to create mineral biosignatures through manipulating the microenvironments in which carbonate precipitation occurs. We used Shewanella oneidensis MR-1, Geothrix fermentans, and Geobacter metallireducens GS-15, representing three different strategies, to reduce solid ferric hydroxide in order to evaluate their influence on carbonate and micropore formation (micro-size porosity in mineral rocks). Our results indicate that electron transfer strategies determined the morphology (rhombohedral, spherical, or long-chained) of precipitated calcium-rich siderite by controlling the level of carbonate saturation and the location of carbonate formation. Remarkably, electron transfer strategies also produced distinctive cell-shaped micropores in both carbonate and hydroxide minerals, thus producing suites of features that could potentially serve as biosignatures recording information about the sizes, shapes, and physiologies of iron-reducing organisms. Key Words: Microbial iron reduction-Micropore-Electron transfer strategies-Microbial carbonate. Astrobiology 18, 28-36.

  12. Long-distance photoinitiated electron transfer through polyene molecular wires

    International Nuclear Information System (INIS)

    Wasielewski, M.R.; Johnson, D.G.; Svec, W.A.; Kersey, K.M.; Cragg, D.E.; Minsek, D.W.

    1989-01-01

    Long-chain polyenes can be used as molecular wires to facilitate electron transfer between a photo-excited donor and an acceptor in an artificial photosynthetic system. The authors present data here on two Zn-porphyrin-polyene-anthraquinone molecules possessing either 5 or 9 all trans double bonds between the donor and acceptor, 1 and 2. The center-to-center distances between the porphyrin and the quinone in these relatively rigid molecules are 25 angstrom for 1 and 35 angstrom for 2. Selective picosecond laser excitation of the Zn-porphyrin and 1 and 2 results in the very rapid transfer of an electron to the anthraquinone in <2 ps and 10 ps, respectively. The resultant radical ion pairs recombine with τ = 10 ps for 1 and τ = 25 ps for 2. The electron transfer rates remain remarkably rapid over these long distances. The involvement of polyene radical cations in the mechanism of the radical ion pair recombination reaction is clear from the transient absorption spectra of 1 and 2, which show strong absorbances in the near-infrared. The strong electronic coupling between the Zn-porphyrin n the anthraquinone provided by low-lying states of the polyene make it possible to transfer an electron rapidly over very long distances

  13. Measurement of the fast electron distribution in laser-plasma experiments in the context of the 'fast ignition' approach to inertial confinement fusion

    International Nuclear Information System (INIS)

    Batani, Dimitri; Morace, Alessio

    2010-01-01

    The recent 'fast ignition approach' to ICF relies on the presence of fast electrons to provide the 'external' ignition spark triggering the nuclear fusion reaction in the compressed core of a thermonuclear target. Such fast electron beam is produced by the interaction of a short-pulse high-intensity laser with the target itself. In this context, it becomes essential to characterize the density of fast electrons and their average energy (i.e. the 'laser to fast electron' energy conversion efficiency) but also the finer details of the velocity and angular distribution. In this work we will discuss several techniques used to determine the fast electron distribution function.

  14. Bimolecular Excited-State Electron Transfer with Surprisingly Long-Lived Radical Ions

    KAUST Repository

    Alsam, Amani Abdu

    2015-09-02

    We explored the excited-state interactions of bimolecular, non-covalent systems consisting of cationic poly[(9,9-di(3,3’-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and 1,4-dicyanobenzene (DCB) using steady-state and time-resolved techniques, including femto- and nanosecond transient absorption and femtosecond infrared spectroscopies with broadband capabilities. The experimental results demonstrated that photo-induced electron transfer from PFN to DCB occurs on the picosecond time scale, leading to the formation of PFN+• and DCB-• radical ions. Interestingly, real-time observations of the vibrational marker modes on the acceptor side provided direct evidence and insight into the electron transfer process indirectly inferred from UV-Vis experiments. The band narrowing on the picosecond time scale observed on the antisymmetric C-N stretching vibration of the DCB radical anion provides clear experimental evidence that a substantial part of the excess energy is channeled into vibrational modes of the electron transfer product and that the geminate ion pairs dissociate. More importantly, our nanosecond time-resolved data indicate that the charge-separated state is very long lived ( 30 ns) due to the dissociation of the contact radical ion pair into free ions. Finally, the fast electron transfer and slow charge recombination anticipate the current donor−acceptor system with potential applications in organic solar cells.

  15. Bimolecular Excited-State Electron Transfer with Surprisingly Long-Lived Radical Ions

    KAUST Repository

    Alsam, Amani Abdu; Aly, Shawkat Mohammede; Usman, Anwar; Parida, Manas R.; Del Gobbo, Silvano; Alarousu, Erkki; Mohammed, Omar F.

    2015-01-01

    We explored the excited-state interactions of bimolecular, non-covalent systems consisting of cationic poly[(9,9-di(3,3’-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and 1,4-dicyanobenzene (DCB) using steady-state and time-resolved techniques, including femto- and nanosecond transient absorption and femtosecond infrared spectroscopies with broadband capabilities. The experimental results demonstrated that photo-induced electron transfer from PFN to DCB occurs on the picosecond time scale, leading to the formation of PFN+• and DCB-• radical ions. Interestingly, real-time observations of the vibrational marker modes on the acceptor side provided direct evidence and insight into the electron transfer process indirectly inferred from UV-Vis experiments. The band narrowing on the picosecond time scale observed on the antisymmetric C-N stretching vibration of the DCB radical anion provides clear experimental evidence that a substantial part of the excess energy is channeled into vibrational modes of the electron transfer product and that the geminate ion pairs dissociate. More importantly, our nanosecond time-resolved data indicate that the charge-separated state is very long lived ( 30 ns) due to the dissociation of the contact radical ion pair into free ions. Finally, the fast electron transfer and slow charge recombination anticipate the current donor−acceptor system with potential applications in organic solar cells.

  16. Numerical simulation of transient moisture transfer into an electronic enclosure

    International Nuclear Information System (INIS)

    Nasirabadi, P. Shojaee; Jabbari, M.; Hattel, J. H.

    2016-01-01

    Electronic systems are sometimes exposed to harsh environmental conditions of temperature and humidity. Moisture transfer into electronic enclosures and condensation can cause several problems such as corrosion and alteration in thermal stresses. It is therefore essential to study the local climate inside the enclosures to be able to protect the electronic systems. In this work, moisture transfer into a typical electronic enclosure is numerically studied using CFD. In order to reduce the CPU-time and make a way for subsequent factorial design analysis, a simplifying modification is applied in which the real 3D geometry is approximated by a 2D axial symmetry one. The results for 2D and 3D models were compared in order to calibrate the 2D representation. Furthermore, simulation results were compared with experimental data and good agreement was found.

  17. Numerical simulation of transient moisture transfer into an electronic enclosure

    Energy Technology Data Exchange (ETDEWEB)

    Nasirabadi, P. Shojaee; Jabbari, M.; Hattel, J. H. [Process Modelling Group, Department of Mechanical Engineering, Technical University of Denmark, Nils Koppels Allé, 2800 Kgs. Lyngby (Denmark)

    2016-06-08

    Electronic systems are sometimes exposed to harsh environmental conditions of temperature and humidity. Moisture transfer into electronic enclosures and condensation can cause several problems such as corrosion and alteration in thermal stresses. It is therefore essential to study the local climate inside the enclosures to be able to protect the electronic systems. In this work, moisture transfer into a typical electronic enclosure is numerically studied using CFD. In order to reduce the CPU-time and make a way for subsequent factorial design analysis, a simplifying modification is applied in which the real 3D geometry is approximated by a 2D axial symmetry one. The results for 2D and 3D models were compared in order to calibrate the 2D representation. Furthermore, simulation results were compared with experimental data and good agreement was found.

  18. Conduction mechanism studies on electron transfer of disordered system

    Institute of Scientific and Technical Information of China (English)

    徐慧; 宋祎璞; 李新梅

    2002-01-01

    Using the negative eigenvalue theory and the infinite order perturbation theory, a new method was developed to solve the eigenvectors of disordered systems. The result shows that eigenvectors change from the extended state to the localized state with the increase of the site points and the disordered degree of the system. When electric field is exerted, the electrons transfer from one localized state to another one. The conductivity is induced by the electron transfer. The authors derive the formula of electron conductivity and find the electron hops between localized states whose energies are close to each other, whereas localized positions differ from each other greatly. At low temperature the disordered system has the character of the negative differential dependence of resistivity and temperature.

  19. Long distance fast data transfer experiments for the ITER Remote Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Yamanaka, Kenjiro, E-mail: yamanaka@nii.ac.jp [National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo (Japan); The Graduate University for Advanced Studies (SOKENDAI), Shonan Village, Hayama, Kanagawa (Japan); Nakanishi, Hideya [National Institute of Fusion Science, 322-6 Orochi, Toki, Gifu (Japan); The Graduate University for Advanced Studies (SOKENDAI), Shonan Village, Hayama, Kanagawa (Japan); Ozeki, Takahisa [Japan Atomic Energy Agency, Obuchi-Omotedate 2-166, Rokkasho, Kamikita, Aomori (Japan); Abe, Shunji; Urushidani, Shigeo [National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo (Japan); The Graduate University for Advanced Studies (SOKENDAI), Shonan Village, Hayama, Kanagawa (Japan); Yamamoto, Takashi [National Institute of Fusion Science, 322-6 Orochi, Toki, Gifu (Japan); Ohtsu, Hideo [Japan Atomic Energy Agency, Obuchi-Omotedate 2-166, Rokkasho, Kamikita, Aomori (Japan); Nakajima, Noriyoshi [National Institute of Fusion Science, 322-6 Orochi, Toki, Gifu (Japan)

    2016-11-15

    Highlights: • This paper presents fast data transfer experiments using packet pacing and mmcftp and results. • An upgrade plan of Japanese Academic Network SINET is also described. • To send the huge amount of data from ITER to the ITER Remote Experiment Center (REC), effective transfer method and super high-speed international network are required. • This paper presents a progress of the investigation for fast transfer method. - Abstract: Developing effective and fast data transfer system for the huge amount data between Europe and Japan is a critical issue for the ITER Remote Experimentation Center (REC). To implement the system, effective data transfer methods and wide bandwidth international network are required. This paper describes results of data transfer experiments. We have evaluated two data transfer methods: Packet Pacing and MMCFTP. By using Packet Pacing and 2.4 Gbps line, we achieved 2.2 Gbps data transfer from NIFS to IFERC. By using MMCFTP and 10 Gbps line, we achieved 2.5 Gbps data transfer from NIFS to Dublin, Ireland. Furthermore, by using MMCFTP and 100Gbps line, we successfully achieved the stable transmission of 1PB of data at approximately 84 Gbps, one of the world’s fastest transmission speeds. This paper also describes the upgrade plan of SINET (a Japanese academic backbone network), which is used for ITER and REC communications. SINET will be upgraded to the network based on 100-Gigabit Ethernet technology in April 2016. Furthermore, direct lines of 20 Gbps (10 Gbps × 2) between Japan and Europe will be introduced. These direct lines will reduce latency between Europe and Japan and will realize higher speed data transfer.

  20. Inelastic electron photon scattering at moderate four momentum transfers

    International Nuclear Information System (INIS)

    Berger, C.; Genzel, H.; Grigull, R.; Lackas, W.; Raupach, F.; Klovning, A.; Lillestoel, E.; Skard, J.A.; Ackermann, H.; Buerger, J.

    1980-10-01

    We present new high statistics data on hadron production in photon photon reactions. The data are analyzed in terms of an electron photon scattering formalism. The dependence of the total cross section on Q 2 , the four momentum transfer squared of the scattered electron, and on the mass W of the hadronic system is investigated. The data are compared to predictions from Vector Dominance and the quark model. (orig.)

  1. Quality assurance and data collection -- Electronic Data Transfer

    International Nuclear Information System (INIS)

    Tomczak, L.M.; Lohner, W.G.; Ray, E.C.; Salesky, J.A.; Spitz, H.B.

    1993-05-01

    The Radiological Environmental Monitoring (REM) group at the Fernald Environmental Management Project is involved in an Electronic Data Transfer practice that will result in the improved quality assurance of collected data. This practice focuses on electronic data transfer from the recording instrument to reduce the manpower normally required for manual data entry and improve the quality of the data transferred. The application of this practice can enhance any data collection program where instruments with electronic memories and a signal output are utilized. Organizations employing this practice can strengthen the quality and efficiency of their data collection program. The use of these practices can assist in complying with Quality Assurance requirements under ASME NQA-1, RCRA, CERCLA, and DOE Order activities. Data from Pylon AB-5 instrumentation is typically configured to print data to a tape. The REM group has developed a process to electronically transfer stored data. The data are sent from the Pylon AB-5 field instrument to a HewlettPackard portable hand computer, model HP95LX. Data are recorded and stored on a 128 K-byte RAN card and later transferred to a PC database as an electronic file for analysis. The advantage of this system is twofold: (1) Data entry errors are eliminated and (2) considerable data collection and entry time is eliminated. Checks can then be conducted for data validity between recorded intervals due to light leaks etc. and the detection of outliers. This paper will discuss the interface and connector components that allow this transfer of data from the Pylon to the PC to take place and the process to perform that activity

  2. Device for transferring fast nuclear reactor fuel assemblies

    International Nuclear Information System (INIS)

    Plagnard, Andre.

    1982-01-01

    The description is given of a device for transferring fuel assemblies between a storage position near the reactor vessel and a position where the irradiated assemblies are evacuated and the provision of new assemblies for the reactor. This device can be dismantled and is movable as a whole for its successive use on several reactors and includes: - a platform mounted so as to rotate on a support made to rest on the structure of the reactor, the platform having at least one opening then being horizontal and mobile about a vertical axis to bring the opening successively in position with vertical wells giving access to the storage and evacuation positions of the assemblies provided in the reactor structure, - at least one hopper that can contain one assembly in a vertical position, located on the upper surface of the platform around the opening provided in it and fitted with a winch for the vertical moving of the assemblies inside the wells and the hopper, when these follow each other by rotation of the platform, - at least one connecting device carried on the platform for connecting the hopper and wells when these are in line [fr

  3. Kinetic Simulation of Fast Electron Transport with Ionization Effects and Ion Acceleration

    International Nuclear Information System (INIS)

    Robinson, A. P. L.; Bell, A. R.; Kingham, R. J.

    2005-01-01

    The generation of relativistic electrons and multi-MeV ions is central to ultra intense (> 1018Wcm-2) laser-solid interactions. The production of energetic particles by lasers has a number of potential applications ranging from Fast Ignition ICF to medicine. In terms of the relativistic (fast) electrons the areas of interest can be divided into three areas. Firstly there is the absorption of laser energy into fast electrons and MeV ions. Secondly there is the transport of fast electrons through the solid target. Finally there is a transduction stage, where the fast electron energy is imparted. This may range from being the electrostatic acceleration of ions at a plasma-vacuum interface, to the heating of a compressed core (as in Fast Ignitor ICF).We have used kinetic simulation codes to study the transport stage and electrostatic ion acceleration. (Author)

  4. Electronic Coupling Dependence of Ultrafast Interfacial Electron Transfer on Nanocrystalline Thin Films and Single Crystal

    Energy Technology Data Exchange (ETDEWEB)

    Lian, Tianquan

    2014-04-22

    The long-term goal of the proposed research is to understand electron transfer dynamics in nanoparticle/liquid interface. This knowledge is essential to many semiconductor nanoparticle based devices, including photocatalytic waste degradation and dye sensitized solar cells.

  5. Electron transfer from nucleobase electron adducts to 5-bromouracil. Is guanine an ultimate sink for the electron in irradiated DNA?

    International Nuclear Information System (INIS)

    Nese, C.; Yuan, Z.; Schuchmann, M.N.; Sonntag, C. von

    1992-01-01

    Electron transfer to 5-bromouracil (5-BrU) from nucleobase (N) electron adducts (and their protonated forms) has been studied by product analysis and pulse radiolysis. When an electron is transferred to 5-BrU, the ensuing 5-BrU radical anion rapidly loses a bromide ion; the uracilyl radical thus formed reacts with added t-butanol, yielding uracil. From the uracil yields measured as the function of [N]/[5-BrU] after γ-radiolysis of Ar-saturated solutions it is concluded that thymine and adenine electron adducts and their heteroatom-protonated forms transfer electrons quantitatively to 5-BrU. The data raise the question whether in DNA the guanine moiety may act as the ultimate sink of the electron in competition with other processes such as protonation at C(6) of the thymine electron adduct. (Author)

  6. Combining UV photodissociation with electron transfer for peptide structure analysis

    Czech Academy of Sciences Publication Activity Database

    Shaffer, C. J.; Marek, Aleš; Pepin, R.; Slováková, K.; Tureček, F.

    2015-01-01

    Roč. 50, č. 3 (2015), s. 470-475 ISSN 1076-5174 Institutional support: RVO:61388963 Keywords : electron transfer dissociation * laser photodissociation * peptide ions * cation radical * chromophores * isomer distinction Subject RIV: CE - Biochemistry Impact factor: 2.541, year: 2015

  7. Electron Transfer in Chemistry and Biology - The Primary Events in ...

    Indian Academy of Sciences (India)

    transfers, occurs in a cascade in many biological processes, including photosynthesis. ... the model reactions of photosynthetic ... biological relevance. GENERAL I ARTICLE of electrons, respectively. This has entirely changed the earlier framework of interpreting reactions in chemistry and biology. This shift in emphasis ...

  8. Electron Transfer in Chemistry and Biology – The Primary Events

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 12. Electron Transfer in Chemistry and Biology – The Primary Events in Photosynthesis. V Krishnan. General Article Volume 2 Issue 12 December 1997 pp 77-86. Fulltext. Click here to view fulltext PDF. Permanent link:

  9. Adsorption and Interfacial Electron Transfer of Saccharomyces Cerevisiae

    DEFF Research Database (Denmark)

    Hansen, Allan Glargaard; Boisen, Anja; Nielsen, Jens Ulrik

    2003-01-01

    We have studied the adsorption and electron-transfer dynamics of Saccharomyces cerevisiae (yeast) iso-l-cytochrome c adsorbed on Au(lll) electrodes in aqueous phosphate buffer media. This cytochrome possesses a thiol group dos e to the protein surface (Cysl02) suitable for linking the protein...

  10. 78 FR 30661 - Electronic Fund Transfers (Regulation E)

    Science.gov (United States)

    2013-05-22

    ... Part 1005 Electronic Fund Transfers (Regulation E); Final Rule #0;#0;Federal Register / Vol. 78 , No... (Regulation E) AGENCY: Bureau of Consumer Financial Protection. ACTION: Final rule; official interpretation.../regulations/final-remittance-rule-amendment-regulation-e/ . SUPPLEMENTARY INFORMATION: I. Summary of the Final...

  11. Towards model-based testing of electronic funds transfer systems

    NARCIS (Netherlands)

    Asaadi, H.R.; Khosravi, R.; Mousavi, M.R.; Noroozi, N.; Arbab, F.; Sirjani, M.

    2012-01-01

    We report on our first experience with applying model-based testing techniques to an operational Electronic Funds Transfer (EFT) switch. The goal is to test the conformance of the EFT switch to the standard flows described by the ISO 8583 standard. To this end, we first make a formalization of the

  12. Towards model-based testing of electronic funds transfer systems

    NARCIS (Netherlands)

    Asaadi, H.R.; Khosravi, R.; Mousavi, M.R.; Noroozi, N.

    2010-01-01

    We report on our first experience with applying model-based testing techniques to an operational Electronic Funds Transfer (EFT) switch. The goal is to test the conformance of the EFT switch to the standard flows described by the ISO 8583 standard. To this end, we first make a formalization of the

  13. Electron transfer kinetics on mono- and multilayer graphene.

    Science.gov (United States)

    Velický, Matěj; Bradley, Dan F; Cooper, Adam J; Hill, Ernie W; Kinloch, Ian A; Mishchenko, Artem; Novoselov, Konstantin S; Patten, Hollie V; Toth, Peter S; Valota, Anna T; Worrall, Stephen D; Dryfe, Robert A W

    2014-10-28

    Understanding of the electrochemical properties of graphene, especially the electron transfer kinetics of a redox reaction between the graphene surface and a molecule, in comparison to graphite or other carbon-based materials, is essential for its potential in energy conversion and storage to be realized. Here we use voltammetric determination of the electron transfer rate for three redox mediators, ferricyanide, hexaammineruthenium, and hexachloroiridate (Fe(CN)(6)(3-), Ru(NH3)(6)(3+), and IrCl(6)(2-), respectively), to measure the reactivity of graphene samples prepared by mechanical exfoliation of natural graphite. Electron transfer rates are measured for varied number of graphene layers (1 to ca. 1000 layers) using microscopic droplets. The basal planes of mono- and multilayer graphene, supported on an insulating Si/SiO(2) substrate, exhibit significant electron transfer activity and changes in kinetics are observed for all three mediators. No significant trend in kinetics with flake thickness is discernible for each mediator; however, a large variation in kinetics is observed across the basal plane of the same flakes, indicating that local surface conditions affect the electrochemical performance. This is confirmed by in situ graphite exfoliation, which reveals significant deterioration of initially, near-reversible kinetics for Ru(NH3)(6)(3+) when comparing the atmosphere-aged and freshly exfoliated graphite surfaces.

  14. 75 FR 75897 - Electronic Funds Transfer of Depository Taxes

    Science.gov (United States)

    2010-12-07

    ... to the particular tax. (b) Income taxes. (1) For provisions relating to the deposits of income and... relating to Federal tax deposits (FTDs) by Electronic Funds Transfer (EFT). In response to the decision of... regulations amending the Income Tax Regulations (26 CFR part 1) and the Regulations on Procedure and...

  15. Electron transfer reactions involving porphyrins and chlorophyll a

    International Nuclear Information System (INIS)

    Neta, P.; Scherz, A.; Levanon, H.

    1979-01-01

    Electron transfer reactions involving porphyrins (P) and quinones (Q) have been studied by pulse radiolysis. The porphyrins used were tetraphenylporphyrin (H 2 TPP), its tetracarboxy derivative (H 2 TCPP), the sodium and zinc compounds (Na 2 TPP and ZnTPP), and chlorophyll a (Chl a). These compounds were found to be rapidly reduced by electron transfer from (CH 3 ) 2 CO - . Reduction by (CH 3 ) 2 COH was rapid in aqueous solutions but relatively slow in i-PrOH solutions. Transient spectra of the anion radicals were determined and, in the case of H 2 TCPP - ., a pK = 9.7 was derived for its protonation. Electron-transfer reactions from the anion radical of H 2 TCPP to benzoquinone, duroquinone, 9,10-anthraquinone 2-sulfonate, and methylviologen occur in aqueous solutions with rate constants approx. 10 7 -10 9 M -1 s -1 which depend on the pH and the quinone reduction potential. Reactions of Na 2 TPP - ., ZnTPP - ., and Chl a - . with anthraquinone in basic i-PrOH solutions occur with rate constants approx. 10 9 M -1 s -1 . The spectral changes associated with these electron-transfer reactions as observed over a period of approx. 1 ms indicated, in some cases, the formation of an intermediate complex [P...Q - .]. 8 figures, 2 tables

  16. 31 CFR 208.3 - Payment by electronic funds transfer.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Payment by electronic funds transfer. 208.3 Section 208.3 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE TREASURY FINANCIAL MANAGEMENT SERVICE MANAGEMENT OF FEDERAL AGENCY...

  17. Charge-transfer properties in the gas electron multiplier

    International Nuclear Information System (INIS)

    Han, Sanghyo; Kim, Yongkyun; Cho, Hyosung

    2004-01-01

    The charge transfer properties of a gas electron multiplier (GEM) were systematically investigated over a broad range of electric field configurations. The electron collection efficiency and the charge sharing were found to depend on the external fields, as well as on the GEM voltage. The electron collection efficiency increased with the collection field up to 90%, but was essentially independent of the drift field strength. A double conical GEM has a 10% gain increase with time due to surface charging by avalanche ions whereas this effect was eliminated with the cylindrical GEM. The positive-ion feedback is also estimated. (author)

  18. Electron-impact ionization of SiCl{sub 3} using an improved crossed fast-neutral-beam - electron-beam apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, J M; Gutkin, M V; Tarnovsky, V; Becker, K [Department of Physics and Engineering Physics, Stevens Institute of Technology, Hoboken, NJ 07030 (United States)], E-mail: kbecker@poly.edu

    2008-05-15

    The fast-neutral-beam technique is a versatile approach to the determination of absolute cross sections for electron-impact ionization of atoms, stable molecules as well as free radicals and metastable species. A fast neutral beam of the species under study is prepared by charge-transfer neutralization of a mass-selected ion beam and the species are subsequently ionized by an electron beam. Mass- and energy-dispersive selection separates singly from multiply charged ions and parent from fragment ions and allows the determination of partial ionization cross sections. Here we describe some major improvements that were made recently to the fast-beam apparatus that has been used extensively for ionization cross section measurements for the past 15 years in our group. Experiments using well-established ionization cross sections in conjunction with extensive ion trajectory simulations were carried out to test the satisfactory performance of the modified fast-neutral-beam apparatus. We also report absolute partial cross sections for the formation of various singly charged positive ions produced by electron impact on SiCl{sub 3} for impact energies from threshold to 200 eV in the modified fast-beam apparatus.

  19. Control of Electron Transfer from Lead-Salt Nanocrystals to TiO 2

    KAUST Repository

    Hyun, Byung-Ryool; Bartnik, A. C.; Sun, Liangfeng; Hanrath, Tobias; Wise, F. W.

    2011-01-01

    The roles of solvent reorganization energy and electronic coupling strength on the transfer of photoexcited electrons from PbS nanocrystals to TiO 2 nanoparticles are investigated. We find that the electron transfer depends only weakly

  20. Doping Phosphorene with Holes and Electrons through Molecular Charge Transfer.

    Science.gov (United States)

    Vishnoi, Pratap; Rajesh, S; Manjunatha, S; Bandyopadhyay, Arkamita; Barua, Manaswee; Pati, Swapan K; Rao, C N R

    2017-11-03

    An important aspect of phosphorene, the novel two-dimensional semiconductor, is whether holes and electrons can both be doped in this material. Some reports found that only electrons can be preferentially doped into phosphorene. There are some theoretical calculations showing charge-transfer interaction with both tetrathiafulvalene (TTF) and tetracyanoethylene (TCNE). We have carried out an investigation of chemical doping of phosphorene by a variety of electron donor and acceptor molecules, employing both experiment and theory, Raman scattering being a crucial aspect of the study. We find that both electron acceptors and donors interact with phosphorene by charge-transfer, with the acceptors having more marked effects. All the three Raman bands of phosphorene soften and exhibit band broadening on interaction with both donor and acceptor molecules. First-principles calculations establish the occurrence of charge-transfer between phosphorene with donors as well as acceptors. The absence of electron-hole asymmetry is noteworthy. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Lifetime measurements in transitional nuclei by fast electronic scintillation timing

    Science.gov (United States)

    Caprio, M. A.; Zamfir, N. V.; Casten, R. F.; Amro, H.; Barton, C. J.; Beausang, C. W.; Cooper, J. R.; Gürdal, G.; Hecht, A. A.; Hutter, C.; Krücken, R.; McCutchan, E. A.; Meyer, D. A.; Novak, J. R.; Pietralla, N.; Ressler, J. J.; Berant, Z.; Brenner, D. S.; Gill, R. L.; Regan, P. H.

    2002-10-01

    A new generation of experiments studying nuclei in spherical-deformed transition regions has been motivated by the introduction of innovative theoretical approaches to the treatment of these nuclei. The important structural signatures in the transition regions, beyond the basic yrast level properties, involve γ-ray transitions between low-spin, non-yrast levels, and so information on γ-ray branching ratios and absolute matrix elements (or level lifetimes) for these transitions is crucial. A fast electronic scintillation timing (FEST) system [H. Mach, R. L. Gill, and M. Moszyński, Nucl. Instrum. Methods A 280, 49 (1989)], making use of BaF2 and plastic scintillation detectors, has been implemented at the Yale Moving Tape Collector for the measurement of lifetimes of states populated in β^ decay. Experiments in the A100 (Pd, Ru) and A150 (Dy, Yb) regions have been carried out, and a few examples will be presented. Supported by the US DOE under grants and contracts DE-FG02-91ER-40609, DE-FG02-88ER-40417, and DE-AC02-98CH10886 and by the German DFG under grant Pi 393/1.

  2. Hyper fast radiative transfer for the physical retrieval of surface parameters from SEVIRI observations

    International Nuclear Information System (INIS)

    Liuzzi, G; Masiello, G; Serio, C; Blasi, M G; Venafra, S

    2015-01-01

    This paper describes the theoretical aspects of a fast scheme for the physical retrieval of surface temperature and emissivity from SEVIRI data, their implementation and some sample results obtained. The scheme is based on a Kalman Filter approach, which effectively exploits the temporal continuity in the observations of the geostationary Meteosat Second Generation (MSG) platform, on which SEVIRI (Spinning Enhanced Visible and InfraRed Imager) operates. Such scheme embodies in its core a physical retrieval algorithm, which employs an hyper fast radiative transfer code highly customized for this retrieval task. Radiative transfer and its customizations are described in detail. Fastness, accuracy and stability of the code are fully documented for a variety of surface features, showing a peculiar application to the massive Greek forest fires in August 2007. (paper)

  3. Vibrationally Assisted Electron Transfer Mechanism of Olfaction: Myth or Reality?

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Chang, Po-Yao; Schulten, Klaus

    2012-01-01

    to this suggestion an olfactory receptor is activated by electron transfer assisted through odorant vibrational excitation. The hundreds to thousands of different olfactory receptors in an animal recognize odorants over a discriminant landscape with surface properties and vibrational frequencies as the two major...... dimensions. In the present paper we introduce the vibrationally assisted mechanism of olfaction and demonstrate for several odorants that, indeed, a strong enhancement of an electron tunneling rate due to odorant vibrations can arise. We discuss in this regard the influence of odorant deuteration and explain...... olfactory receptors and odorants must obey for the vibrationally assisted electron transfer mechanism to function. We argue that the stated characteristics are feasible for realistic olfactory receptors, noting, though, that the receptor structure presently is still unknown, but can be studied through...

  4. Water Activated Graphene Oxide Transfer Using Wax Printed Membranes for Fast Patterning of a Touch Sensitive Device.

    Science.gov (United States)

    Baptista-Pires, Luis; Mayorga-Martínez, Carmen C; Medina-Sánchez, Mariana; Montón, Helena; Merkoçi, Arben

    2016-01-26

    We demonstrate a graphene oxide printing technology using wax printed membranes for the fast patterning and water activation transfer using pressure based mechanisms. The wax printed membranes have 50 μm resolution, longtime stability and infinite shaping capability. The use of these membranes complemented with the vacuum filtration of graphene oxide provides the control over the thickness. Our demonstration provides a solvent free methodology for printing graphene oxide devices in all shapes and all substrates using the roll-to-roll automatized mechanism present in the wax printing machine. Graphene oxide was transferred over a wide variety of substrates as textile or PET in between others. Finally, we developed a touch switch sensing device integrated in a LED electronic circuit.

  5. Syntrophic Growth via Quinone-Mediated Interspecies Electron Transfer

    Directory of Open Access Journals (Sweden)

    Jessica A Smith

    2015-02-01

    Full Text Available The mechanisms by which microbial species exchange electrons are of interest because interspecies electron transfer can expand the metabolic capabilities of microbial communities. Previous studies with the humic substance analog anthraquinone-2,6-disulfonate (AQDS suggested that quinone-mediated interspecies electron transfer (QUIET is feasible, but it was not determined if sufficient energy is available from QUIET to support the growth of both species. Furthermore, there have been no previous studies on the mechanisms for the oxidation of anthrahydroquinone-2,6-disulfonate (AHQDS. A co-culture of Geobacter metallireducens and Geobacter sulfurreducens metabolized ethanol with the reduction of fumarate much faster in the presence of AQDS, and there was an increase in cell protein. G. sulfurreducens was more abundant, consistent with G. sulfurreducens obtaining electrons from acetate that G. metallireducens produced from ethanol, as well as from AHQDS. Cocultures initiated with a citrate synthase-deficient strain of G. sulfurreducens that was unable to use acetate as an electron donor also metabolized ethanol with the reduction of fumarate and cell growth, but acetate accumulated over time. G. sulfurreducens and G. metallireducens were equally abundant in these co-cultures reflecting the inability of the citrate synthase-deficient strain of G. sulfurreducens to metabolize acetate. Evaluation of the mechanisms by which G. sulfurreducens accepts electrons from AHQDS demonstrated that a strain deficient in outer-surface c-type cytochromes that are required for AQDS reduction was as effective at QUIET as the wild-type strain. Deletion of additional genes previously implicated in extracellular electron transfer also had no impact on QUIET. These results demonstrate that QUIET can yield sufficient energy to support the growth of both syntrophic partners, but that the mechanisms by which electrons are derived from extracellular hydroquinones require

  6. Mechanism of enhancement of controllable secondary-electron emission from fast single electrons

    International Nuclear Information System (INIS)

    Lorikyan, M.P.; Kavalov, R.L.; Trofimchuk, N.N.; Arvanov, A.N.; Gavalyan, V.G.

    For porous KCl films (density approximately 2 percent, thickness 50-400 μm), the controllable secondary electron emission (CSEE) from fast single electrons with energies of 0.7-2 MeV was studied. An electric field E of approximately 10 4 -10 5 V/cm was set up inside the porous films and the emission curves anti sigma = f(E) and the energy spectra of the secondary electrons were measured. The mean emission coefficient anti sigma increases with increasing E, reaching a value of anti sigma approximately equal to 230. Internal enhancement of CSEE under the action of the E field is explained by a process similar to the Townsend semi-self-maintained discharge in gases. The mean free path L/sub e/ of the secondary electrons estimated on the basis of this mechanism of CSEE enhancement is in good agreement with the L/sub e/ value obtained independently from the energy spectra of the secondary electrons. The report examines the effect of the first critical potential U/sub il/ and of the electron affinity of the dielectric α on the formation of CSEE from a porous dielectric film. The possibility of using such films in particle detectors is discussed

  7. Nonlocal effects in a bounded low-temperature plasma with fast electrons

    International Nuclear Information System (INIS)

    DeJoseph, C. A. Jr.; Demidov, V. I.; Kudryavtsev, A. A.

    2007-01-01

    Effects associated with nonlocality of the electron energy distribution function (EEDF) in a bounded, low-temperature plasma containing fast electrons, can lead to a significant increase in the near-wall potential drop, leading to self-trapping of fast electrons in the plasma volume, even if the density of this group is only a small fraction (∼0.001%) of the total electron density. If self-trapping occurs, the fast electrons can substantially increase the rate of stepwise excitation, supply additional heating to slow electrons, and reduce their rate of diffusion cooling. Altering the source terms of these fast electrons will, therefore, alter the near-wall sheath and, through modification of the EEDF, a number of plasma parameters. Self-trapping of fast electrons is important in a variety of plasmas, including hollow-cathode discharges and capacitive rf discharges, and is especially pronounced in an afterglow plasma, which is a key phase of any pulse-modulated discharge. In the afterglow, the electron temperature is less than a few tenths of an electron volt, and the fast electrons will have energies typically greater than an electron volt. It is shown that in the afterglow plasma of noble gases, fast electrons, arising from Penning ionization of metastable atoms, can lead to the above condition and significantly change the plasma and sheath properties. Similar effects can be important in technologically relevant electronegative gas plasmas, where fast electrons can arise due to electron detachment in collisions of negative ions with atomic species. Both experimental and modeling results are presented to illustrate these effects

  8. Simulation of solution phase electron transfer in a compact donor-acceptor dyad.

    Science.gov (United States)

    Kowalczyk, Tim; Wang, Lee-Ping; Van Voorhis, Troy

    2011-10-27

    Charge separation (CS) and charge recombination (CR) rates in photosynthetic architectures are difficult to control, yet their ratio can make or break photon-to-current conversion efficiencies. A rational design approach to the enhancement of CS over CR requires a mechanistic understanding of the underlying electron-transfer (ET) process, including the role of the environment. Toward this goal, we introduce a QM/MM protocol for ET simulations and use it to characterize CR in the formanilide-anthraquinone dyad (FAAQ). Our simulations predict fast recombination of the charge-transfer excited state, in agreement with recent experiments. The computed electronic couplings show an electronic state dependence and are weaker in solution than in the gas phase. We explore the role of cis-trans isomerization on the CR kinetics, and we find strong correlation between the vertical energy gaps of the full simulations and a collective solvent polarization coordinate. Our approach relies on constrained density functional theory to obtain accurate diabatic electronic states on the fly for molecular dynamics simulations, while orientational and electronic polarization of the solvent is captured by a polarizable force field based on a Drude oscillator model. The method offers a unified approach to the characterization of driving forces, reorganization energies, electronic couplings, and nonlinear solvent effects in light-harvesting systems.

  9. Energy distribution of the fast electron from Cu and CH targets irradiated with fs-laser pulses

    International Nuclear Information System (INIS)

    Cai Dafeng; Gu Yuqiu; Zheng Zhijian; Zhou Weimin; Jiao Chunye

    2014-01-01

    In order to investigate the effect of target's material on fast electron energy distribution, the energy distribution of fast electrons from the front and the rear of Cu and CH targets have been measured during the interaction of femtosecond laser-foil targets. The results show that the fast electron spectrums from the front of Cu and CH targets are similar, which show energy distribution of fast electrons depends very little on material of targets. The fast electron spectrums from the rear of Cu and CH targets are obviously dissimilar, which indicate a mighty effect of target material on fast electron transport. The fast electron spectrums from the Cu target is 'soften', which is due to electron recirculation and self-magnetic field produced by electrons transported in the target. The fast electron spectrums from the CH target is a Maxwellian distribution, which is due to collision effect when electrons transport in the target. (authors)

  10. Electron Transfer Strategies Regulate Carbonate Mineral and Micropore Formation

    Science.gov (United States)

    Zeng, Zhirui; Tice, Michael M.

    2018-01-01

    Some microbial carbonates are robust biosignatures due to their distinct morphologies and compositions. However, whether carbonates induced by microbial iron reduction have such features is unknown. Iron-reducing bacteria use various strategies to transfer electrons to iron oxide minerals (e.g., membrane-bound enzymes, soluble electron shuttles, nanowires, as well as different mechanisms for moving over or attaching to mineral surfaces). This diversity has the potential to create mineral biosignatures through manipulating the microenvironments in which carbonate precipitation occurs. We used Shewanella oneidensis MR-1, Geothrix fermentans, and Geobacter metallireducens GS-15, representing three different strategies, to reduce solid ferric hydroxide in order to evaluate their influence on carbonate and micropore formation (micro-size porosity in mineral rocks). Our results indicate that electron transfer strategies determined the morphology (rhombohedral, spherical, or long-chained) of precipitated calcium-rich siderite by controlling the level of carbonate saturation and the location of carbonate formation. Remarkably, electron transfer strategies also produced distinctive cell-shaped micropores in both carbonate and hydroxide minerals, thus producing suites of features that could potentially serve as biosignatures recording information about the sizes, shapes, and physiologies of iron-reducing organisms.

  11. Electron transfer oxidation of DNA radicals by paranitroacetophenone

    Energy Technology Data Exchange (ETDEWEB)

    Whillans, D W; Adams, G E [Mount Vernon Hospital, Northwood (UK)

    1975-12-01

    The reaction of a typical electron-affinic sensitizer, paranitroacetophenone (PNAP) with the model compounds thymine, thymidine, thymidylic acid, deoxyribose and single and double-stranded DNA has been investigated by pulse radiolysis. Radicals formed by one-electron reduction of the bases and of DNA reacted rapidly and efficiently with PNAP by electron transfer. A small yield of transfer (< 10 per cent) was also observed arising from oxidation of the radicals formed by the small proportion of OH which reacted at the sugar moieties in DNA. In contrast, electron transfer oxidation by PNAP of radicals formed by the addition of OH to the base moieties, e.g. thymine, was not an efficient process. Further, addition of the sensitizer to the thymine OH-adduct proceeded at a rate that was too low to measure the pulse radiolysis. We conclude that, since the major sites of OH reaction by DNA are the heterocyclic bases (> 80 per cent), oxidation of the resultant radicals is unlikely to be a major step in the mechanism of sensitization by this typical hypoxic-cell sensitizer.

  12. Electron Transfer Mechanisms of DNA Repair by Photolyase

    Science.gov (United States)

    Zhong, Dongping

    2015-04-01

    Photolyase is a flavin photoenzyme that repairs two DNA base damage products induced by ultraviolet (UV) light: cyclobutane pyrimidine dimers and 6-4 photoproducts. With femtosecond spectroscopy and site-directed mutagenesis, investigators have recently made significant advances in our understanding of UV-damaged DNA repair, and the entire enzymatic dynamics can now be mapped out in real time. For dimer repair, six elementary steps have been characterized, including three electron transfer reactions and two bond-breaking processes, and their reaction times have been determined. A unique electron-tunneling pathway was identified, and the critical residues in modulating the repair function at the active site were determined. The dynamic synergy between the elementary reactions for maintaining high repair efficiency was elucidated, and the biological nature of the flavin active state was uncovered. For 6-4 photoproduct repair, a proton-coupled electron transfer repair mechanism has been revealed. The elucidation of electron transfer mechanisms and two repair photocycles is significant and provides a molecular basis for future practical applications, such as in rational drug design for curing skin cancer.

  13. Electron Transfer between Electrically Conductive Minerals and Quinones

    Directory of Open Access Journals (Sweden)

    Olga Taran

    2017-07-01

    Full Text Available Long-distance electron transfer in marine environments couples physically separated redox half-reactions, impacting biogeochemical cycles of iron, sulfur and carbon. Bacterial bio-electrochemical systems that facilitate electron transfer via conductive filaments or across man-made electrodes are well-known, but the impact of abiotic currents across naturally occurring conductive and semiconductive minerals is poorly understood. In this paper I use cyclic voltammetry to explore electron transfer between electrodes made of common iron minerals (magnetite, hematite, pyrite, pyrrhotite, mackinawite, and greigite, and hydroquinones—a class of organic molecules found in carbon-rich sediments. Of all tested minerals, only pyrite and magnetite showed an increase in electric current in the presence of organic molecules, with pyrite showing excellent electrocatalytic performance. Pyrite electrodes performed better than commercially available glassy carbon electrodes and showed higher peak currents, lower overpotential values and a smaller separation between oxidation and reduction peaks for each tested quinone. Hydroquinone oxidation on pyrite surfaces was reversible, diffusion controlled, and stable over a large number of potential cycles. Given the ubiquity of both pyrite and quinones, abiotic electron transfer between minerals and organic molecules is likely widespread in Nature and may contribute to several different phenomena, including anaerobic respiration of a wide variety of microorganisms in temporally anoxic zones or in the proximity of hydrothermal vent chimneys, as well as quinone cycling and the propagation of anoxic zones in organic rich waters. Finally, interactions between pyrite and quinones make use of electrochemical gradients that have been suggested as an important source of energy for the origins of life on Earth. Ubiquinones and iron sulfide clusters are common redox cofactors found in electron transport chains across all domains

  14. Electron Transfer Between Electrically Conductive Minerals and Quinones

    Science.gov (United States)

    Taran, Olga

    2017-07-01

    Long-distance electron transfer in marine environments couples physically separated redox half-reactions, impacting biogeochemical cycles of iron, sulfur and carbon. Bacterial bio-electrochemical systems that facilitate electron transfer via conductive filaments or across man-made electrodes are well known, but the impact of abiotic currents across naturally occurring conductive and semiconducitve minerals is poorly understood. In this paper I use cyclic voltammetry to explore electron transfer between electrodes made of common iron minerals (magnetite, hematite, pyrite, pyrrhotite, mackinawite and greigite), and hydroquinones - a class of organic molecules found in carbon-rich sediments. Of all tested minerals, only pyrite and magnetite showed an increase in electric current in the presence of organic molecules, with pyrite showing excellent electrocatalytic performance. Pyrite electrodes performed better than commercially available glassy carbon electrodes and showed higher peak currents, lower overpotential values and a smaller separation between oxidation and reduction peaks for each tested quinone. Hydroquinone oxidation on pyrite surfaces was reversible, diffusion controlled, and stable over a large number of potential cycles. Given the ubiquity of both pyrite and quinones, abiotic electron transfer between minerals and organic molecules is likely widespread in Nature and may contribute to several different phenomena, including anaerobic respiration of a wide variety of microorganisms in temporally anoxic zones or in the proximity of hydrothermal vent chimneys, as well as quinone cycling and the propagation of anoxic zones in organic rich waters. Finally, interactions between pyrite and quinones make use of electrochemical gradients that have been suggested as an important source of energy for the origins of life on Earth. Ubiquinones and iron sulfide clusters are common redox cofactors found in electron transport chains across all domains of life and

  15. Fast electron and X-ray scattering as a tool to study target's structure

    Energy Technology Data Exchange (ETDEWEB)

    Amusia, M.Ya. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); A.F. Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russian Federation)], E-mail: amusia@vms.huji.ac.il

    2007-06-15

    We concentrate on several relatively new aspects of the study of fast electron and X-ray scattering by atoms and atom-like objects, namely endohedral atoms and fullerenes. However, main attention is given to fast charge particle scattering. We show that the corresponding cross-sections, being expressed via so-called generalized oscillator strengths (GOS), give information on the electronic structure of the target and on the role of electron correlations in it. We consider what sort of information became available when analyzing the dependence of GOS upon their multipolarity, transferred momentum q and energy {omega}. To obtain theoretical results, we employ both the one-electron Hartree-Fock approximation and account for the multi-electron correlation in the target, using the random phase approximation with exchange. We demonstrate the role of non-dipole corrections in the small-angle fast-electron inelastic scattering. There dipole contribution dominates while non-dipole corrections can be considerably and controllably enhanced as compared to the case of low and medium energy photoionization. We show also that analyses of GOS for discrete level excitations permit to clarify their multipolarity. The results of calculations of Compton excitation and ionization cross-sections are presented. Attention is given to cooperative effects in inelastic fast electron-atom scattering that results in directed motion of the secondary electrons, a phenomenon that is similar to 'drag currents' in photoionization. We demonstrate how one should derive GOS for endohedral atoms, e.g. A-C{sub 60} and what is the additional information that can be obtained from corresponding GOS. Most of discussions are illustrated by the results of concrete calculations.

  16. Sensitivity of Electron Transfer Mediated Decay to Ion Pairing.

    Science.gov (United States)

    Pohl, Marvin N; Richter, Clemens; Lugovoy, Evgeny; Seidel, Robert; Slavíček, Petr; Aziz, Emad F; Abel, Bernd; Winter, Bernd; Hergenhahn, Uwe

    2017-08-17

    Ion pairing in electrolyte solutions remains a topic of discussion despite a long history of research. Very recently, nearest-neighbor mediated electronic de-excitation processes of core hole vacancies (electron transfer mediated decay, ETMD) were proposed to carry a spectral fingerprint of local solvation structure and in particular of contact ion pairs. Here, for the first time, we apply electron-electron coincidence detection to a liquid microjet, and record ETMD spectra of Li 1s vacancies in aqueous solutions of lithium chloride (LiCl) in direct comparison to lithium acetate (LiOAc). A change in the ETMD spectrum dependent on the electrolyte anion identity is observed for 4.5 M salt concentration. We discuss these findings within the framework of the formation and presence of contact ion pairs and the unique sensitivity of ETMD spectroscopy to ion pairing.

  17. Charge-transfer collisions involving few-electron systems

    International Nuclear Information System (INIS)

    Kirchner, T.

    2016-01-01

    Ion-atom collision systems that involve more than one electron constitute nonseparable few-body problems, whose full solution is difficult to say the least. At impact energies well below 1 keV/amu an expansion of the stationary scattering wave function in terms of a limited number of products of nuclear and molecular state wave functions (amended to satisfy scattering boundary conditions) is feasible and usually sufficient to obtain accurate charge-transfer cross sections provided the electronic wave functions include configuration interaction. At energies above 1 keV/amu this approach becomes inefficient and close-coupling methods within the semi classical approximation are better suited to treat the problem. For bare-ion collisions from helium target atoms explicit solutions of the two-electron time-dependent Schrödinger equation can be achieved, but are computationally costly and cannot be extended to problems which involve more than two electrons.

  18. Large scale oil lease automation and electronic custody transfer

    International Nuclear Information System (INIS)

    Price, C.R.; Elmer, D.C.

    1995-01-01

    Typically, oil field production operations have only been automated at fields with long term production profiles and enhanced recovery. The automation generally consists of monitoring and control at the wellhead and centralized facilities. However, Union Pacific Resources Co. (UPRC) has successfully implemented a large scale automation program for rapid-decline primary recovery Austin Chalk wells where purchasers buy and transport oil from each individual wellsite. This project has resulted in two significant benefits. First, operators are using the system to re-engineer their work processes. Second, an inter-company team created a new electronic custody transfer method. This paper will describe: the progression of the company's automation objectives in the area; the field operator's interaction with the system, and the related benefits; the research and development of the new electronic custody transfer method

  19. Photoinduced electron transfer in singly labeled thiouredopyrenetrisulfonate azurin derivatives

    DEFF Research Database (Denmark)

    Borovok, N; Kotlyar, A B; Pecht, I

    1999-01-01

    efficiency. TUPS derivatives of azurin, singly labeled at specific lysine residues, were prepared and purified to homogeneity by ion exchange HPLC. Transient absorption spectroscopy was used to directly monitor the rates of the electron transfer reaction from the photoexcited triplet state of TUPS to Cu......A novel method for the initiation of intramolecular electron transfer reactions in azurin is reported. The method is based on laser photoexcitation of covalently attached thiouredopyrenetrisulfonate (TUPS), the reaction that generates the low potential triplet state of the dye with high quantum......(II) and the back reaction from Cu(I) to the oxidized dye. For all singly labeled derivatives, the rate constants of copper ion reduction were one or two orders of magnitude larger than for its reoxidation, consistent with the larger thermodynamic driving force for the former process. Using 3-D coordinates...

  20. Ab Initio Analysis of Auger-Assisted Electron Transfer.

    Science.gov (United States)

    Hyeon-Deuk, Kim; Kim, Joonghan; Prezhdo, Oleg V

    2015-01-15

    Quantum confinement in nanoscale materials allows Auger-type electron-hole energy exchange. We show by direct time-domain atomistic simulation and analytic theory that Auger processes give rise to a new mechanism of charge transfer (CT) on the nanoscale. Auger-assisted CT eliminates the renown Marcus inverted regime, rationalizing recent experiments on CT from quantum dots to molecular adsorbates. The ab initio simulation reveals a complex interplay of the electron-hole and charge-phonon channels of energy exchange, demonstrating a variety of CT scenarios. The developed Marcus rate theory for Auger-assisted CT describes, without adjustable parameters, the experimental plateau of the CT rate in the region of large donor-acceptor energy gap. The analytic theory and atomistic insights apply broadly to charge and energy transfer in nanoscale systems.

  1. Syntrophic growth with direct interspecies electron transfer as the primary mechanism for energy exchange

    DEFF Research Database (Denmark)

    Shrestha, Pravin Malla; Rotaru, Amelia-Elena; Aklujkar, Muktak

    2013-01-01

    Direct interspecies electron transfer (DIET) through biological electrical connections is an alternative to interspecies H2 transfer as a mechanism for electron exchange in syntrophic cultures. However, it has not previously been determined whether electrons received via DIET yield energy...... dehydrogenase, the pilus-associated c-type cytochrome OmcS and pili consistent with electron transfer via DIET. These results suggest that electrons transferred via DIET can serve as the sole energy source to support anaerobic respiration....

  2. Characterization of the fast electrons distribution produced in a high intensity laser target interaction

    Energy Technology Data Exchange (ETDEWEB)

    Westover, B. [Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093 (United States); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Chen, C. D.; Patel, P. K.; McLean, H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Beg, F. N., E-mail: fbeg@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093 (United States)

    2014-03-15

    Experiments on the Titan laser (∼150 J, 0.7 ps, 2 × 10{sup 20} W cm{sup −2}) at the Lawrence Livermore National Laboratory were carried out in order to study the properties of fast electrons produced by high-intensity, short pulse laser interacting with matter under conditions relevant to Fast Ignition. Bremsstrahlung x-rays produced by these fast electrons were measured by a set of compact filter-stack based x-ray detectors placed at three angles with respect to the target. The measured bremsstrahlung signal allows a characterization of the fast electron beam spectrum, conversion efficiency of laser energy into fast electron kinetic energy and angular distribution. A Monte Carlo code Integrated Tiger Series was used to model the bremsstrahlung signal and infer a laser to fast electron conversion efficiency of 30%, an electron slope temperature of about 2.2 MeV, and a mean divergence angle of 39°. Simulations were also performed with the hybrid transport code ZUMA which includes fields in the target. In this case, a conversion efficiency of laser energy to fast electron energy of 34% and a slope temperature between 1.5 MeV and 4 MeV depending on the angle between the target normal direction and the measuring spectrometer are found. The observed temperature of the bremsstrahlung spectrum, and therefore the inferred electron spectrum are found to be angle dependent.

  3. Heat transfer from the roughened surface of gas cooled fast breeder reactor fuel element

    International Nuclear Information System (INIS)

    Tang, I.M.

    1979-01-01

    The temperature distributions and the augmentation of heat transfer performance by artificial roughening of a gas cooled fast breeder reactor (GCFR) fuel rod cladding are studied. Numerical solutions are based on the axisymmetric assumption for a two-dimensional model for one rib pitch of axial distance. The local and axial clad temperature distributions are obtained for both the rectangular and ramp rib roughened surface geometries. The transformation of experimentally measured convective heat transfer coefficients, in terms of Stanton number, into GCFR values is studied. In addition, the heat transfer performance of a GCFR fuel rod cladding roughened surface design is evaluated. Approximate analytical solution for correlating an average Stanton number is also obtained and satisfactorily compared with the corresponding numerical result for a GCFR design. The analytical correlation is useful in assessing roughened surface heat transfer performance in scoping studies and conceptual design

  4. Allenylidene Complexes of Ruthenium: Synthesis, Spectroscopy and Electron Transfer Properties

    Czech Academy of Sciences Publication Activity Database

    Winter, R. F.; Záliš, Stanislav

    2004-01-01

    Roč. 248, 15/16 (2004), s. 1565-1583 ISSN 0010-8545 R&D Projects: GA ČR GA203/03/0821; GA MŠk OC D14.20 Institutional research plan: CEZ:AV0Z4040901 Keywords : spectroscopy * allenylidine complexes of ruthenium * electron transfer Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.446, year: 2004

  5. Blocking layer modeling for temperature analysis of electron transfer ...

    African Journals Online (AJOL)

    In this article, we simulate thermal effects on the electron transfer rate from three quantum dots CdSe, CdS and CdTe to three metal oxides TiO2, SnO2 and ZnO2 in the presence of four blocking layers ZnS, ZnO, TiO2 and Al2O3, in a porous quantum dot sensitized solar cell (QDSSC) structure, using Marcus theory.

  6. Marcus wins nobel prize in chemistry for electron transfer theory

    International Nuclear Information System (INIS)

    Levi, B.G.

    1993-01-01

    This article describes the work of Rudolf Marcus of Caltech leading to his receipt of the 1992 Nobel Prize in Chemistry open-quotes for his contributions to the theory of electron transfer reactions in chemical systems.close quotes Applications of Marcus' theory include such diverse phenomena as photosynthesis, electrically conducting polymers, chemiluminescence, and corrosion. Historical aspects of his career are given. 10 refs., 1 fig

  7. [Electron transfer, ionization and excitation in atomic collisions

    International Nuclear Information System (INIS)

    1991-01-01

    The research being carried out at Penn State by Winter and Alston addresses the fundamental atomic-collision processes of electron transfer, ionization, and excitation. Winter has focussed attention on intermediate and, more recently, higher collision energies -- proton energies of at least about 50 keV -- for which coupled-state approaches are appropriate. Alston has concentrated on perturbative approaches to symmetric ion-ion/atom collisions at high energies and to asymmetric collisions at intermediate to high energies

  8. Magnetic electron scattering from deuterium at low-momentum transfer

    International Nuclear Information System (INIS)

    Jones, E.C. Jr.; Bendel, W.L.; Fagg, L.W.; Lindgren, R.A.

    1980-01-01

    The elastic and inelastic cross sections of deuterium for 56.4 MeV electrons scattered at 180 0 , have been measured up to an excitation energy of 19 MeV. The experimental cross sections are compared with those calculated by Miller, by Durand, and by Arenhoevel and Fabian, and also with the sum rules of O'Connell. The results indicate that the contribution of meson exchange currents at this low-momentum transfer is significant

  9. Fast-electron-impact study on excitations of 4p, 4s, and 3d electrons of krypton

    International Nuclear Information System (INIS)

    Yuan Zhensheng; Zhu Linfan; Liu Xiaojing; Li Wenbin; Cheng Huadong; Xu Kezun; Zhong Zhiping

    2002-01-01

    Absolute optical oscillator strength densities for the excitations of the electrons 4p, 4s, and 3d have been measured. Their absolute optical oscillator strengths have also been obtained. An enhancement above the 4p ionization threshold in the photoabsorption spectrum was assigned as a delayed maximum which arises from the photoionization process of 4p→εd according to present Dirac-Slater calculation. In the energy region of 4s autoionization, we have observed several features that are absent in previous fast-electron-impact work, but exist in optical measurements. We clarify this discrepancy here. Two Rydberg series of optically forbidden transitions, i.e., 4s -1 ns( 1 S) (n=5,6,7) and 4s -1 nd( 1 D) (n=4,5,6,7) have been observed when the spectrometer worked at conditions with larger momentum transfers, namely, K 2 =0.23 a.u. and 0.67 a.u. Furthermore, the absolute optical oscillator strengths for the 3d excitation have been obtained

  10. Ultrafast Photoinduced Electron Transfer in Bimolecular Donor-Acceptor Systems

    KAUST Repository

    Alsulami, Qana A.

    2016-11-30

    The efficiency of photoconversion systems, such as organic photovoltaic (OPV) cells, is largely controlled by a series of fundamental photophysical processes occurring at the interface before carrier collection. A profound understanding of ultrafast interfacial charge transfer (CT), charge separation (CS), and charge recombination (CR) is the key determinant to improving the overall performances of photovoltaic devices. The discussion in this dissertation primarily focuses on the relevant parameters that are involved in photon absorption, exciton separation, carrier transport, carrier recombination and carrier collection in organic photovoltaic devices. A combination of steady-state and femtosecond broadband transient spectroscopies was used to investigate the photoinduced charge carrier dynamics in various donor-acceptor systems. Furthermore, this study was extended to investigate some important factors that influence charge transfer in donor-acceptor systems, such as the morphology, energy band alignment, electronic properties and chemical structure. Interestingly, clear correlations among the steady-state measurements, time-resolved spectroscopy results, grain alignment of the electron transporting layer (ETL), carrier mobility, and device performance are found. In this thesis, we explored the significant impacts of ultrafast charge separation and charge recombination at donor/acceptor (D/A) interfaces on the performance of a conjugated polymer PTB7-Th device with three fullerene acceptors: PC71BM, PC61BM and IC60BA. Time-resolved laser spectroscopy and high-resolution electron microscopy can illustrate the basis for fabricating solar cell devices with improved performances. In addition, we studied the effects of the incorporation of heavy metals into π-conjugated chromophores on electron transfer by monitoring the triplet state lifetime of the oligomer using transient absorption spectroscopy, as understanding the mechanisms controlling intersystem crossing and

  11. Rapid long range intramolecular electron transfer within a steroid molecule with two electron binding groups

    International Nuclear Information System (INIS)

    Huddleston, R.K.; Miller, J.R.

    1983-01-01

    Intramolecular electron transfer has been observed to have occurred in less than 100 ns in a steroid molecule having two distinct electron binding groups separated by distances distributed from 7--11 A. Experiments were carried out in organic glasses at 77 K with pulse radiolysis techniques to create trapped electrons which were captured by a group on one end of the steroid molecule. Although one of the groups, benzoate, is held to the steroid spacer by a flexible linkage, the rigidity of the glassy matrices prevented movement to alter the initial distance. Interestingly, no effects of distance were seen: all ET processes appeared to have occurred much faster than our 100 ns time resolution, consistent with measurements of the rate of intermolecular electron transfer between the same functional groups in random solutions. Solvation energetics, on the other hand, had a remarkable influence on the extent and direction of electron transfer. A change in solvent polarity was observed to reverse the direction of electron transfer. Evidence was obtained for a distribution of solvation environments for ions in glasses which may be as broad as 0.15 eV

  12. Intercellular wiring enables electron transfer between methanotrophic archaea and bacteria.

    Science.gov (United States)

    Wegener, Gunter; Krukenberg, Viola; Riedel, Dietmar; Tegetmeyer, Halina E; Boetius, Antje

    2015-10-22

    The anaerobic oxidation of methane (AOM) with sulfate controls the emission of the greenhouse gas methane from the ocean floor. In marine sediments, AOM is performed by dual-species consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB) inhabiting the methane-sulfate transition zone. The biochemical pathways and biological adaptations enabling this globally relevant process are not fully understood. Here we study the syntrophic interaction in thermophilic AOM (TAOM) between ANME-1 archaea and their consortium partner SRB HotSeep-1 (ref. 6) at 60 °C to test the hypothesis of a direct interspecies exchange of electrons. The activity of TAOM consortia was compared to the first ANME-free culture of an AOM partner bacterium that grows using hydrogen as the sole electron donor. The thermophilic ANME-1 do not produce sufficient hydrogen to sustain the observed growth of the HotSeep-1 partner. Enhancing the growth of the HotSeep-1 partner by hydrogen addition represses methane oxidation and the metabolic activity of ANME-1. Further supporting the hypothesis of direct electron transfer between the partners, we observe that under TAOM conditions, both ANME and the HotSeep-1 bacteria overexpress genes for extracellular cytochrome production and form cell-to-cell connections that resemble the nanowire structures responsible for interspecies electron transfer between syntrophic consortia of Geobacter. HotSeep-1 highly expresses genes for pili production only during consortial growth using methane, and the nanowire-like structures are absent in HotSeep-1 cells isolated with hydrogen. These observations suggest that direct electron transfer is a principal mechanism in TAOM, which may also explain the enigmatic functioning and specificity of other methanotrophic ANME-SRB consortia.

  13. Aspects of the physics and chemistry of water radiolysis by fast neutrons and fast electrons in nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    McCracken, D.R. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Tsang, K.T. [Atomic Energy of Canada Limited, Mississauga, Ontario (Canada); Laughton, P.J

    1998-09-01

    Detailed radiation physics calculations of energy deposition have been done for the coolant of CANDU reactors and Pressurized Water Reactors (PWRs). The geometry of the CANDU fuel channel was modelled in detail. Fluxes and energy-deposition rates for neutrons, recoil ions, photons, and fast electrons have been calculated using MCNP4B, WIMS-AECL, and specifically derived energy-transfer factors. These factors generate the energy/flux spectra of recoil ions from fast-neutron energy/flux spectra. The energy spectrum was divided into 89 discrete ranges (energy bins).The production of oxidizing species and net coolant radiolysis can be suppressed by the addition of hydrogen to the coolant of nuclear reactors. It is argued that the net dissociation of coolant by gamma rays is suppressed by lower levels of excess hydrogen than when dissociation is by ion recoils. This has consequences for the modelling of coolant radiolysis by homogeneous kinetics. More added hydrogen is required to stop water radiolysis by recoil ions acting alone than if recoil ions and gamma rays acted concurrently in space and time. Homogeneous kinetic models and experimental data suggest that track overlap is very inefficient in providing radicals from gamma-ray tracks to recombine molecular products in ion-recoil tracks. An inhomogeneous chemical model is needed that incorporates ionizing-particle track structure and track overlap. Such a model does not yet exist, but a number of limiting cases using homogeneous kinetics are discussed. There are sufficient uncertainties and contradictions in the data relevant to the radiolysis of reactor coolant that the relatively high CHC's (critical hydrogen concentration) observed in NRU reactor experiments (compared to model predictions) may be explainable by errors in fundamental data and understanding of water radiolysis under reactor conditions. The radiation chemistry program at CRL has been focused to generate quantitative water-radiolysis data in a

  14. Study on enhancement of heat transfer of reactor vessel auxiliary cooling system of fast breeder reactor

    International Nuclear Information System (INIS)

    Nishi, Yoshihisa; Kinoshita, Izumi; Ueda, Nobuyuki; Furuya, Masahiro

    1996-01-01

    A reactor vessel auxiliary cooling system (RVACS), which is one of the decay heat removal systems of the fast breeder reactor (FBR), has passive safety as well as high reliability. However, the heat removal capability is relatively small, because its heat exchange is dependent on the natural convection of the air. The objectives of this report are to propose a heat transfer medium to enhance the heat transfer and to confirm the heat transfer performance of this system by experimental and analytical studies. From these studies, the following main results were obtained. (1) A porous plate with 5 mm thickness, 5 mm pore diameter, 92% porosity, was found to have the highest enhancement of heat transfer. (2) The heat transfer enhancement was demonstrated by large scale heat transfer experiments. Also, the heat transfer correlations, which can be used in the plant transient analyses, were derived from the experimental results. (3) Analysing the transient conditions of conventional pool-type FBR by means of the system analysis code, the applicable range of this system was assumed from the capability of the RVACS with porous plates. As a result, this type of RVACS was found to be applicable to conventional pool-type FBRs with capacity of about 500 MWe or less. (author)

  15. Nonadiabatic two-electron transfer mediated by an irregular bridge

    International Nuclear Information System (INIS)

    Petrov, E.G.; Shevchenko, Ye.V.; May, V.

    2004-01-01

    Nonadiabatic two-electron transfer (TET) mediated by a linear molecular bridge is studied theoretically. Special attention is put on the case of a irregular distribution of bridge site energies as well as on the inter-site Coulomb interaction. Based on the unified description of electron transfer reactions [J. Chem. Phys. 115 (2001) 7107] a closed set of kinetic equations describing the TET process is derived. A reduction of this set to a single exponential donor-acceptor (D-A) TET is performed together with a derivation of an overall D-A TET rate. The latter contains a contribution of the stepwise as well as of the concerted route of D-A TET. The stepwise contribution is determined by two single-electron steps each of them associated with a sequential and a superexchange pathway. A two-electron unistep superexchange transition between the D and A forms the concerted contribution to the overall rate. Both contributions are analyzed in their dependency on the bridge length. The irregular distribution of the bridge site energies as well as the influence of the Coulomb interaction facilitates the D-A TET via a modification of the stepwise and the concerted part of the overall rate. At low temperatures and for short bridges with a single or two units the concerted contribution exceeds the stepwise contribution. If the bridge contains more than two units, the stepwise contribution dominates the overall rate

  16. Electron transfer. 88. Cobalt(III)-bound phosphite and hypophosphite

    International Nuclear Information System (INIS)

    Linn, D.E. Jr.; Gould, E.S.

    1987-01-01

    Phosphite and hypophosphite coordinate to cobalt(III) in (NH 3 ) 5 Co/sup III/ through oxygen, rather than through phosphorus. The resulting complexes undergo electron-transfer reactions with Ru(NH 3 ) 6 2+ much more slowly than with Eu 2+ or V 2+ , indicating that the latter two reactants preferentially utilize ligand bridging. Reductions with Cr 2+ are shown to accompanied by transfer of the phosphorus-containing ligands, and reaction of the protonated phosphito (biphosphito) derivative (pK/sub A/ = 3.06 at 23 0 C) proceeds through a combination of acid-independent and inverse-acid paths, both routes yielding the same phosphito-bound Cr(III) product. The hypophosphito, but not the biphosphito, complex reacts with Ce(IV), producing Co 2+ in an induced electron-transfer process. The yield of Co 2+ falls off progressively as [Ce/sup IV/] is increased, pointing to a sequence in which a Co(III)-bound P(II) radical is formed in initial attack by Ce(IV) but subsequently undergoes partition between competing reaction paths, i.e. internal electron transfer to Co(III) vs external oxidation by a second Ce(IV) center. The hypophosphito complex, but not the biphosphito complex, smoothly decomposes in basic media via an internal redox reaction, yielding Co(II) quantitatively, along with a 1:1 mixture of phosphite, and hypophosphite. This transformation, which fails with mixtures of (NH 3 ) 5 Co(H 2 O) 3+ and H 2 PO 2 - appears to be catalyzed specifically by OH - . Deuterium-labeling experiments disclose a solvent isotope effect. Reaction mechanisms are suggested for all the observed results. 54 references, 5 tables

  17. Electron transfer, ionization, and excitation in atomic collisions

    International Nuclear Information System (INIS)

    Winter, T.G.; Alston, S.G.

    1992-01-01

    The research being carried out at Penn State by Winter and Alston addresses the fundamental processes of electron transfer, ionization, and excitation in ion-atom (and ion-ion) collisions. The focus is on intermediate- and higher-energy collisions, corresponding to proton energies of about 25 kilo-electron-volts (keV) or larger. At intermediate energies, where the transition probabilities are not small, many states must be coupled in a large calculation, while at higher energies, perturbative approaches may be used. Several studies have been carried out in the current three-year period; most of these treat systems with only one or two electrons, so that fewer approximations need be made and the basic collisional mechanisms can be more clearly described

  18. Cherenkov-type diamond detectors for measurements of fast electrons in the TORE-SUPRA tokamak

    International Nuclear Information System (INIS)

    Jakubowski, L.; Sadowski, M. J.; Zebrowski, J.; Rabinski, M.; Malinowski, K.; Mirowski, R.; Lotte, Ph.; Gunn, J.; Pascal, J-Y.; Colledani, G.; Basiuk, V.; Goniche, M.; Lipa, M.

    2010-01-01

    The paper presents a schematic design and tests of a system applicable for measurements of fast electron pulses emitted from high-temperature plasma generated inside magnetic confinement fusion machines, and particularly in the TORE-SUPRA facility. The diagnostic system based on the registration of the Cherenkov radiation induced by fast electrons within selected solid radiators is considered, and electron low-energy thresholds for different radiators are given. There are some estimates of high thermal loads, which might be deposited by intense electron beams upon parts of the diagnostic equipment within the TORE-SUPRA device. There are some proposed measures to overcome this difficulty by the selection of appropriate absorption filters and Cherenkov radiators, and particularly by the application of a fast-moving reciprocating probe. The paper describes the measuring system, its tests, as well as some results of the preliminary measurements of fast electrons within TORE-SUPRA facility.

  19. Cherenkov-type diamond detectors for measurements of fast electrons in the TORE-SUPRA tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Jakubowski, L.; Sadowski, M. J.; Zebrowski, J.; Rabinski, M.; Malinowski, K.; Mirowski, R. [Andrzej Soltan Institute for Nuclear Studies (IPJ), Otwock-Swierk 05-400 (Poland); Lotte, Ph.; Gunn, J.; Pascal, J-Y.; Colledani, G.; Basiuk, V.; Goniche, M.; Lipa, M. [CEA, IRFM, St Paul-lez-Durance F-13108 (France)

    2010-01-15

    The paper presents a schematic design and tests of a system applicable for measurements of fast electron pulses emitted from high-temperature plasma generated inside magnetic confinement fusion machines, and particularly in the TORE-SUPRA facility. The diagnostic system based on the registration of the Cherenkov radiation induced by fast electrons within selected solid radiators is considered, and electron low-energy thresholds for different radiators are given. There are some estimates of high thermal loads, which might be deposited by intense electron beams upon parts of the diagnostic equipment within the TORE-SUPRA device. There are some proposed measures to overcome this difficulty by the selection of appropriate absorption filters and Cherenkov radiators, and particularly by the application of a fast-moving reciprocating probe. The paper describes the measuring system, its tests, as well as some results of the preliminary measurements of fast electrons within TORE-SUPRA facility.

  20. Absence of quantum oscillations in electronic excitation transfer in the Fenna-Matthews-Olson complex

    Science.gov (United States)

    Eisfeld, Alexander; Ritschel, Gerhard; Roden, Jan; Strunz, Walter; Aspuru-Guzik, Alan

    2012-02-01

    Energy transfer in the photosynthetic Fenna-Matthews-Olson (FMO) complex of the Green Sulfur Bacteria is studied theoretically taking all three subunits (monomers) of the FMO trimer and the recently found eighth bacteriochlorophyll (BChl) molecule into account. For the calculations we use the efficient Non-Markovian Quantum State diffusion approach. Since it is believed that the eighth BChl is located near the main light harvesting antenna we look at the differences in transfer between the situation when BChl 8 is initially excited and the usually considered case when BChl 1 or 6 is initially excited. We find strong differences in the transfer dynamics, both qualitatively and quantitatively. When the excited state dynamics is initialized at site eight of the FMO complex, we see a slow exponential-like decay of the excitation. This is in contrast to the oscillations and a relatively fast transfer that occurs when only seven sites or initialization at sites 1 and 6 is considered. Additionally we show that differences in the values of the electronic transition energies found in the literature lead to a large difference in the transfer dynamics.

  1. Coulomb blockade and transfer of electrons one by one

    International Nuclear Information System (INIS)

    Pothier, Hugues

    1991-01-01

    Zero point fluctuations of the charge on the capacitance of a tunnel junction connected to a bias circuit are in almost all experimental situations larger than the electron charge. As a consequence, the effects of charge granularity are hidden, but in circuits with 'islands', which are electrodes connected to the rest of the circuit only through tunnel junctions and capacitors. The island charge being quantized, its fluctuations are blocked. If the island capacitance is sufficiently small, no electron can enter the island because of the increase of electrostatic energy that would occur. We have observed this effect, called 'Coulomb blockade', in the 'single electron box', where an island is formed between a tunnel junction and a capacitor. A bias voltage source coupled to the island through the capacitor allows to control the number of electrons. We have designed and operated two devices with nano-scale tunnel junctions based on this principle, the 'turnstile' and the 'pump', through which the current is controlled electron by electron. In our experiments, the precision of the transfer is of the order of one percent. It should be a million time better in versions of these devices with more junctions. One could then use them for a new measurement of the fine structure constant alpha. (author) [fr

  2. Direct observation of the ultrafast electron transfer process in a polymer/fullerene blend

    NARCIS (Netherlands)

    Cerullo, G.; Lanzani, G.; Silvestri, S. De; Brabec, Ch.J.; Zerza, G.; Sariciftci, N.S.; Hummelen, J.C.

    2000-01-01

    Photoinduced electron transfer in organic molecules is an extensively investigated topic both because of fundamental interest in the photophysics and for applications to artificial photosynthesis. Highly efficient ultrafast electron transfer from photoexcited conjugated polymers to C60 has been

  3. 77 FR 34127 - Financial Management Service; Proposed Collection of Information: Electronic Transfer Account...

    Science.gov (United States)

    2012-06-08

    ... Information: Electronic Transfer Account (ETA) Financial Agency Agreement AGENCY: Financial Management Service... of information described below: Title: Electronic Transfer Account (ETA) Financial Agency Agreement... public and other Federal agencies to take this opportunity to comment on a continuing information...

  4. Interspecies Electron Transfer during Propionate and Butyrate Degradation in Mesophilic, Granular Sludge

    OpenAIRE

    Schmidt, J. E.; Ahring, B. K.

    1995-01-01

    Granules from a mesophilic upflow anaerobic sludge blanket reactor were disintegrated, and bacteria utilizing only hydrogen or formate or both hydrogen and formate were added to investigate the role of interspecies electron transfer during degradation of propionate and butyrate. The data indicate that the major electron transfer occurred via interspecies hydrogen transfer, while interspecies formate transfer may not be essential for interspecies electron transfer in this system during degrada...

  5. Electronic and vibronic properties of a discotic liquid-crystal and its charge transfer complex

    Energy Technology Data Exchange (ETDEWEB)

    Haverkate, Lucas A.; Mulder, Fokko M. [Reactor Institute Delft, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands); Zbiri, Mohamed, E-mail: zbiri@ill.fr; Johnson, Mark R. [Institut Laue Langevin, 38042 Grenoble Cedex 9 (France); Carter, Elizabeth [Vibrational Spectroscopy Facility, School of Chemistry, The University of Sydney, NSW 2008 (Australia); Kotlewski, Arek; Picken, S. [ChemE-NSM, Faculty of Chemistry, Delft University of Technology, 2628BL/136 Delft (Netherlands); Kearley, Gordon J. [Bragg Institute, Australian Nuclear Science and Technology Organisation, Menai, NSW 2234 (Australia)

    2014-01-07

    Discotic liquid crystalline (DLC) charge transfer (CT) complexes combine visible light absorption and rapid charge transfer characteristics, being favorable properties for photovoltaic (PV) applications. We present a detailed study of the electronic and vibrational properties of the prototypic 1:1 mixture of discotic 2,3,6,7,10,11-hexakishexyloxytriphenylene (HAT6) and 2,4,7-trinitro-9-fluorenone (TNF). It is shown that intermolecular charge transfer occurs in the ground state of the complex: a charge delocalization of about 10{sup −2} electron from the HAT6 core to TNF is deduced from both Raman and our previous NMR measurements [L. A. Haverkate, M. Zbiri, M. R. Johnson, B. Deme, H. J. M. de Groot, F. Lefeber, A. Kotlewski, S. J. Picken, F. M. Mulder, and G. J. Kearley, J. Phys. Chem. B 116, 13098 (2012)], implying the presence of permanent dipoles at the donor-acceptor interface. A combined analysis of density functional theory calculations, resonant Raman and UV-VIS absorption measurements indicate that fast relaxation occurs in the UV region due to intramolecular vibronic coupling of HAT6 quinoidal modes with lower lying electronic states. Relatively slower relaxation in the visible region the excited CT-band of the complex is also indicated, which likely involves motions of the TNF nitro groups. The fast quinoidal relaxation process in the hot UV band of HAT6 relates to pseudo-Jahn-Teller interactions in a single benzene unit, suggesting that the underlying vibronic coupling mechanism can be generic for polyaromatic hydrocarbons. Both the presence of ground state CT dipoles and relatively slow relaxation processes in the excited CT band can be relevant concerning the design of DLC based organic PV systems.

  6. Ultrafast Interfacial Electron and Hole Transfer from CsPbBr3 Perovskite Quantum Dots.

    Science.gov (United States)

    Wu, Kaifeng; Liang, Guijie; Shang, Qiongyi; Ren, Yueping; Kong, Degui; Lian, Tianquan

    2015-10-14

    Recently reported colloidal lead halide perovskite quantum dots (QDs) with tunable photoluminescence (PL) wavelengths covering the whole visible spectrum and exceptionally high PL quantum yields (QYs, 50-90%) constitute a new family of functional materials with potential applications in light-harvesting and -emitting devices. By transient absorption spectroscopy, we show that the high PL QYs (∼79%) can be attributed to negligible electron or hole trapping pathways in CsPbBr3 QDs: ∼94% of lowest excitonic states decayed with a single-exponential time constant of 4.5 ± 0.2 ns. Furthermore, excitons in CsPbBr3 QDs can be efficiently dissociated in the presence of electron or hole acceptors. The half-lives of electron transfer (ET) to benzoquinone and subsequent charge recombination are 65 ± 5 ps and 2.6 ± 0.4 ns, respectively. The half-lives for hole transfer (HT) to phenothiazine and the subsequent charge recombination are 49 ± 6 ps and 1.0 ± 0.2 ns, respectively. The lack of electron and hole traps and fast interfacial ET and HT rates are key properties that may enable the development of efficient lead halide perovskite QDs-based light-harvesting and -emitting devices.

  7. Kinetics of electron transfer through ferrocene-terminated alkanethiol monolayers on gold

    Energy Technology Data Exchange (ETDEWEB)

    Smalley, J.F.; Feldberg, S.W.; Newton, M.D.; Liu, Y.P. [Brookhaven National Lab., Upton, NY (United States); Chidsey, C.E.D.; Linford, M.R. [Stanford Univ., CA (United States)

    1995-08-31

    The kinetics of electron transfer between a substrate gold electrode and a self-assembled monolayer formed from CH{sub 3}(CH{sub 2}){sub n-1}SH and ({eta}{sup 5} C{sub 5}H{sub 5})Fe ({eta}{sup 5}-C{sub 5}H{sub 4})CO{sub 2}(CH{sub 2}){sub n}SH were studied as a function of n, the number of methylenes in the alkyl chain tethering the ferrocene moiety to the electrode, using the indirect laser-induced temperature jump method (ILIT). For 5 {<=} n {<=} 9 the standard electron-transfer rate constants vary according to {kappa}{sub {tau}a,n=0} exp[-{beta}{sub n}n] where {kappa}{sub {tau}a,n=0} is the (extrapolated) rate constant for the electron transfer at n = 0. At {Tau} = 25{degree}C, {kappa}{sub {tau}a,n} 0 {approx_equal} 6 x 10{sup 8} s{sup -1} and {beta}{sub n} = 1.21 x 0.05. The ILIT method allows rates to be measured that are too fast to be measured by conventional chronoamperometry at a macroelectrode, which is limited to rate constants of {<=} 10{sup 4} s{sup -1}. Using a Marcus formalism, the reorganization energy, {lambda}, for the electron-transfer process at a given n was determined from the slope of an Arrhenius plot over the temperature range 15-55{degree}C. Values of {lambda} determined from Arrhenius slopes for n = 8 and 9 using ILIT are in reasonable agreement with the value of {lambda} previously deduced from the potential dependence of the rate constant for n = 16. 39 refs., 13 figs., 3 tabs.

  8. A computationally efficient method for full-core conjugate heat transfer modeling of sodium fast reactors

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Rui, E-mail: rhu@anl.gov; Yu, Yiqi

    2016-11-15

    Highlights: • Developed a computationally efficient method for full-core conjugate heat transfer modeling of sodium fast reactors. • Applied fully-coupled JFNK solution scheme to avoid the operator-splitting errors. • The accuracy and efficiency of the method is confirmed with a 7-assembly test problem. • The effects of different spatial discretization schemes are investigated and compared to the RANS-based CFD simulations. - Abstract: For efficient and accurate temperature predictions of sodium fast reactor structures, a 3-D full-core conjugate heat transfer modeling capability is developed for an advanced system analysis tool, SAM. The hexagon lattice core is modeled with 1-D parallel channels representing the subassembly flow, and 2-D duct walls and inter-assembly gaps. The six sides of the hexagon duct wall and near-wall coolant region are modeled separately to account for different temperatures and heat transfer between coolant flow and each side of the duct wall. The Jacobian Free Newton Krylov (JFNK) solution method is applied to solve the fluid and solid field simultaneously in a fully coupled fashion. The 3-D full-core conjugate heat transfer modeling capability in SAM has been demonstrated by a verification test problem with 7 fuel assemblies in a hexagon lattice layout. Additionally, the SAM simulation results are compared with RANS-based CFD simulations. Very good agreements have been achieved between the results of the two approaches.

  9. Overpotential-induced lability of the electronic overlap factor in long-range electrochemical electron transfer: charge and distance dependence

    DEFF Research Database (Denmark)

    Kornyshev, A. A.; Kuznetsov, A. M.; Nielsen, Jens Ulrik

    2000-01-01

    Long-distance electrochemical electron transfer exhibits approximately exponential dependence on the electron transfer distance. On the basis of a jellium model of the metal surface we show that the slope of the logarithm of the current vs. the transfer distance also depends strongly...

  10. Sub-picosecond timing fluctuation suppression in laser-based atmospheric transfer of microwave signal using electronic phase compensation

    Science.gov (United States)

    Chen, Shijun; Sun, Fuyu; Bai, Qingsong; Chen, Dawei; Chen, Qiang; Hou, Dong

    2017-10-01

    We demonstrated a timing fluctuation suppression in outdoor laser-based atmospheric radio-frequency transfer over a 110 m one-way free-space link using an electronic phase compensation technique. Timing fluctuations and Allan Deviation are both measured to characterize the instability of transferred frequency incurred during the transfer process. With transferring a 1 GHz microwave signal over a timing fluctuation suppressed transmission link, the total root-mean-square (rms) timing fluctuation was measured to be 920 femtoseconds in 5000 s, with fractional frequency instability on the order of 1 × 10-12 at 1 s, and order of 2 × 10-16 at 1000 s. This atmospheric frequency transfer scheme with the timing fluctuation suppression technique can be used to fast build an atomic clock-based frequency free-space transmission link since its stability is superior to a commercial Cs and Rb clock.

  11. Fast electron beam charge injection and switching in dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Fitting, Hans-Joachim; Schreiber, Erik [Institute of Physics, University of Rostock, Universitaetsplatz 3, 18051 Rostock (Germany); Touzin, Matthieu [Laboratoire de Structure et Proprietes de l' Etat Solide, UMR CNRS 8008, Universite de Lille 1, 59655 Villeneuve d' Ascq (France)

    2011-04-15

    Basic investigations of secondary electrons (SE) relaxation and attenuation are made by means of Monte Carlo simulations using ballistic electron scattering and interactions with optical and acoustic phonons as well as impact ionization of valence band electrons. Then the electron beam induced selfconsistent charge transport and secondary electron emission in insulators are described by means of an electron-hole flight-drift model (FDM). Ballistic secondary electrons and holes, their attenuation and drift, as well as their recombination, trapping, and field- and temperature-dependent Poole-Frenkel detrapping are included. Whereas the initial switching-on of the secondary electron emission proceeds over milli-seconds due to long-lasting selfconsistent charging, the switching-off process occurs much faster, even over femto-seconds. Thus a rapid electron beam switching becomes possible with formation of ultra-short electron beam pulses offering an application in stroboscopic electron microscopy and spectroscopy. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. 36 CFR 1235.48 - What documentation must agencies transfer with electronic records?

    Science.gov (United States)

    2010-07-01

    ... documentation for the following types of electronic records: (i) E-mail messages with attachments; (ii) Scanned... agencies transfer with electronic records? 1235.48 Section 1235.48 Parks, Forests, and Public Property... agencies transfer with electronic records? (a) General. Agencies must transfer documentation adequate to...

  13. Triboelectric effect: A new perspective on electron transfer process

    Science.gov (United States)

    Pan, Shuaihang; Zhang, Zhinan

    2017-10-01

    As interest in the triboelectric effect increases in line with the development of tribo-electrification related devices, the mechanisms involved in this phenomenon require more systematic review from the dual perspectives of developed classical insights and emerging quantum understanding. In this paper, the clear energy changing and transferring process of electrons have been proposed from the quantum point of view as the trigger for the charging initiation process in the triboelectric effect, and the phonon modes on the friction surfaces are believed to hold great importance as one of the main driving forces. Compatible with Maxwell Displacement Current theory, the complete consideration for charging steady state, i.e., the competition mechanisms between the breakdown process and the continuously charging process, and the balance mechanisms of phonon-electron interaction, built voltage, and induced polarization, are illustrated. In brief, the proposed theory emphasizes the fundamental role of electron transferring in tribo-electrical fields. By comparing certain experimental results from the previous studies, the theory is justified.

  14. Microbial interspecies electron transfer via electric currents through conductive minerals

    Science.gov (United States)

    Kato, Souichiro; Hashimoto, Kazuhito; Watanabe, Kazuya

    2012-01-01

    In anaerobic biota, reducing equivalents (electrons) are transferred between different species of microbes [interspecies electron transfer (IET)], establishing the basis of cooperative behaviors and community functions. IET mechanisms described so far are based on diffusion of redox chemical species and/or direct contact in cell aggregates. Here, we show another possibility that IET also occurs via electric currents through natural conductive minerals. Our investigation revealed that electrically conductive magnetite nanoparticles facilitated IET from Geobacter sulfurreducens to Thiobacillus denitrificans, accomplishing acetate oxidation coupled to nitrate reduction. This two-species cooperative catabolism also occurred, albeit one order of magnitude slower, in the presence of Fe ions that worked as diffusive redox species. Semiconductive and insulating iron-oxide nanoparticles did not accelerate the cooperative catabolism. Our results suggest that microbes use conductive mineral particles as conduits of electrons, resulting in efficient IET and cooperative catabolism. Furthermore, such natural mineral conduits are considered to provide ecological advantages for users, because their investments in IET can be reduced. Given that conductive minerals are ubiquitously and abundantly present in nature, electric interactions between microbes and conductive minerals may contribute greatly to the coupling of biogeochemical reactions. PMID:22665802

  15. Covalent electron transfer chemistry of graphene with diazonium salts.

    Science.gov (United States)

    Paulus, Geraldine L C; Wang, Qing Hua; Strano, Michael S

    2013-01-15

    Graphene is an atomically thin, two-dimensional allotrope of carbon with exceptionally high carrier mobilities, thermal conductivity, and mechanical strength. From a chemist's perspective, graphene can be regarded as a large polycyclic aromatic molecule and as a surface without a bulk contribution. Consequently, chemistries typically performed on organic molecules and surfaces have been used as starting points for the chemical functionalization of graphene. The motivations for chemical modification of graphene include changing its doping level, opening an electronic band gap, charge storage, chemical and biological sensing, making new composite materials, and the scale-up of solution-processable graphene. In this Account, we focus on graphene functionalization via electron transfer chemistries, in particular via reactions with aryl diazonium salts. Because electron transfer chemistries depend on the Fermi energy of graphene and the density of states of the reagents, the resulting reaction rate depends on the number of graphene layers, edge states, defects, atomic structure, and the electrostatic environment. We limit our Account to focus on pristine graphene over graphene oxide, because free electrons in the latter are already bound to oxygen-containing functionalities and the resulting chemistries are dominated by localized reactivity and defects. We describe the reaction mechanism of diazonium functionalization of graphene and show that the reaction conditions determine the relative degrees of chemisorption and physisorption, which allows for controlled modulation of the electronic properties of graphene. Finally we discuss different applications for graphene modified by this chemistry, including as an additive in polymer matrices, as biosensors when coupled with cells and biomolecules, and as catalysts when combined with nanoparticles.

  16. Comparison of dynamical aspects of nonadiabatic electron, proton, and proton-coupled electron transfer reactions

    International Nuclear Information System (INIS)

    Hatcher, Elizabeth; Soudackov, Alexander; Hammes-Schiffer, Sharon

    2005-01-01

    The dynamical aspects of a model proton-coupled electron transfer (PCET) reaction in solution are analyzed with molecular dynamics simulations. The rate for nonadiabatic PCET is expressed in terms of a time-dependent probability flux correlation function. The impact of the proton donor-acceptor and solvent dynamics on the probability flux is examined. The dynamical behavior of the probability flux correlation function is dominated by a solvent damping term that depends on the energy gap correlation function. The proton donor-acceptor motion does not impact the dynamical behavior of the probability flux correlation function but does influence the magnitude of the rate. The approximations previously invoked for the calculation of PCET rates are tested. The effects of solvent damping on the proton donor-acceptor vibrational motion are found to be negligible, and the short-time solvent approximation, in which only equilibrium fluctuations of the solvent are considered, is determined to be valid for these types of reactions. The analysis of PCET reactions is compared to previous analyses of single electron and proton transfer reactions. The dynamical behavior is qualitatively similar for all three types of reactions, but the time scale of the decay of the probability flux correlation function is significantly longer for single proton transfer than for PCET and single electron transfer due to a smaller solvent reorganization energy for proton transfer

  17. Observation of electron-transfer-mediated decay in aqueous solution

    Science.gov (United States)

    Unger, Isaak; Seidel, Robert; Thürmer, Stephan; Pohl, Marvin N.; Aziz, Emad F.; Cederbaum, Lorenz S.; Muchová, Eva; Slavíček, Petr; Winter, Bernd; Kryzhevoi, Nikolai V.

    2017-07-01

    Photoionization is at the heart of X-ray photoelectron spectroscopy (XPS), which gives access to important information on a sample's local chemical environment. Local and non-local electronic decay after photoionization—in which the refilling of core holes results in electron emission from either the initially ionized species or a neighbour, respectively—have been well studied. However, electron-transfer-mediated decay (ETMD), which involves the refilling of a core hole by an electron from a neighbouring species, has not yet been observed in condensed phase. Here we report the experimental observation of ETMD in an aqueous LiCl solution by detecting characteristic secondary low-energy electrons using liquid-microjet soft XPS. Experimental results are interpreted using molecular dynamics and high-level ab initio calculations. We show that both solvent molecules and counterions participate in the ETMD processes, and different ion associations have distinctive spectral fingerprints. Furthermore, ETMD spectra are sensitive to coordination numbers, ion-solvent distances and solvent arrangement.

  18. Electron Transfer and Solvent-Mediated Electronic Localization in Molecular Photocatalysis

    DEFF Research Database (Denmark)

    Dohn, Asmus Ougaard; Kjær, Kasper Skov; Harlang, Tobias B.

    2016-01-01

    This work provides a detailed mechanism for electron transfer in a heterodinuclear complex designed as a model system in which to study homogeneous molecular photocatalysis. With efficient Born–Oppenheimer molecular dynamics simulations, we show how intermediate, charge-separated states can mediate...

  19. Sausage instabilities in the electron current layer and its role in the concept of fast ignition

    International Nuclear Information System (INIS)

    Das, Amita; Jain, Neeraj; Kaw, Predhiman; Sengupta, Sudip

    2004-01-01

    The fast ignition concept of laser fusion utilizes hot electrons produced at the surface of the target by an incident intense laser pulse for the creation of the hot spot for ignition. As the hot electrons move inwards to the core of the precompressed target, the electrons from the background plasma provide a return shielding current. Three dimensional PIC simulations have shown that intense Weibel, tearing and coalescence instabilities take place which organize the current distribution into a few current filaments. In each of these filaments the central core region constitutes a current due to the fast electrons propagating inwards towards the pellet core, while the outer cylindrical shell region carries the return shielding current. The presence of instabilities and their subsequent nonlinear development can hinder the propagation of fast electrons towards the core influencing the location of the hot spot for ignition. Earlier studies showing the existence of sausage-like modes were carried out in the nonrelativistic limit and under the assumption of equal electron densities of the fast and the cold electrons. The fast electron density, in general, differs considerably from the background plasma density as it is dependent on the incident laser intensity. This paper incorporates relativistic effects and also studies the dependence of the growth rate on the fast electron density. Finally, nonlinear saturation of the instability and its impact on the stopping of the fast electron motion towards the core have also been investigated using numerical simulations. The simulations have, however, currently been carried out for non-relativistic dynamics. The results show that the sheared velocity profile of the channel gets flattened, causing an effective drop in the inward moving current. (author)

  20. Light induced electron transfer reactions of metal complexes

    International Nuclear Information System (INIS)

    Sutin, N.; Creutz, C.

    1980-01-01

    Properties of the excited states of tris(2,2'-bipyridine) and tris(1,10-phenanthroline) complexes of chromium(III), iron(II), ruthenium(II), osmium(II), rhodium(III), and iridium(III) are described. The electron transfer reactions of the ground and excited states are discussed and interpreted in terms of the driving force for the reaction and the distortions of the excited states relative to the corresponding ground states. General considerations relevant to the conversion of light into chemical energy are presented and progress in the use of polypyridine complexes to effect the light decomposition of water into hydrogen and oxygen is reviewed

  1. Towards model-based testing of electronic funds transfer systems

    OpenAIRE

    Asaadi, H.R.; Khosravi, R.; Mousavi, M.R.; Noroozi, N.

    2010-01-01

    We report on our first experience with applying model-based testing techniques to an operational Electronic Funds Transfer (EFT) switch. The goal is to test the conformance of the EFT switch to the standard flows described by the ISO 8583 standard. To this end, we first make a formalization of the transaction flows specified in the ISO 8583 standard in terms of a Labeled Transition System (LTS). This formalization paves the way for model-based testing based on the formal notion of Input-Outpu...

  2. Exciplex formation and electron transfer in polychromophoric systems

    International Nuclear Information System (INIS)

    Yang, N.C.C.; Minsek, D.W.; Johnson, D.G.; Wasielewski, M.R.

    1989-01-01

    This paper discusses the rates of excited anthracene decay and intramolecular exciplex formation from biochromophoric molecules containing an anthryl group and an amine donor which vary with the length of the chain link, the nature of the amine donor and the viscosity of the medium. According to the authors, the results indicate that the intramolecular exciplex formation may proceed via more than one pathway. Experimental results suggest that electron transfer from the amino donor to the excited anthryl group may play a role in the exciplex formation in viscous alkanes

  3. Large momentum transfer electron scattering from few-nucleon systems

    International Nuclear Information System (INIS)

    Arnold, R.G.

    1979-08-01

    A review is given of the experimental results from a series of measurements at SLAC of large momentum transfer (Q 2 > 20 fm -2 ) electron scattering at forward angles from nuclei with A less than or equal to 4. Theoretical interpretations of these data in terms of traditional nuclear physics models and in terms of quark constituent models are described. Some physics questions for future experiments are explored, and a preview of possible future measurements of magnetic structure functions of light nuclei at large Q 2 is given

  4. Photochemical reactions of electron-deficient olefins with N,N,N',N'-tetramethylbenzidine via photoinduced electron-transfer

    Energy Technology Data Exchange (ETDEWEB)

    Pan Yang [Laboratory of Bond-selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, No. 96 of Jinzhai Road, Hefei, Anhui 230026 (China); Zhao Junshu [Laboratory of Bond-selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, No. 96 of Jinzhai Road, Hefei, Anhui 230026 (China); Ji Yuanyuan [Laboratory of Bond-selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, No. 96 of Jinzhai Road, Hefei, Anhui 230026 (China); Yan Lei [Laboratory of Bond-selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, No. 96 of Jinzhai Road, Hefei, Anhui 230026 (China); Yu Shuqin [Laboratory of Bond-selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, No. 96 of Jinzhai Road, Hefei, Anhui 230026 (China)], E-mail: sqyu@ustc.edu.cn

    2006-01-05

    Photoinduced electron transfer reactions of several electron-deficient olefins with N,N,N',N'-tetramethylbenzidine (TMB) in acetonitrile solution have been studied by using laser flash photolysis technique and steady-state fluorescence quenching method. Laser pulse excitation of TMB yields {sup 3}TMB* after rapid intersystem crossing from {sup 1}TMB*. The triplet which located at 480 nm is found to undergo fast quenching with the electron acceptors fumaronitrile (FN), dimethyl fumarate (DMF), diethyl fumarate (DEF), cinnamonitrile (CN), {alpha}-acetoxyacrylonitrile (AAN), crotononitrile (CrN) and 3-methoxyacrylonitrile (MAN). Substituents binding to olefin molecule own different electron-donating/withdrawing powers, which determine the electron-deficient property ({pi}-cloud density) of olefin molecule as well as control the electron transfer rate constant directly. The detection of ion radical intermediates in the photolysis reactions confirms the proposed electron transfer mechanism, as expected from thermodynamics. The quenching rate constants of triplet TMB by these olefins have been determined at 510 nm to avoid the disturbance of formed TMB cation radical around 475 nm. All the k{sub q}{sup T} values approach or reach to the diffusion-controlled limit. In addition, fluorescence quenching rate constants k{sub q}{sup S} have been also obtained by calculating with Stern-Volmer equation. A correlation between experimental electron transfer rate constants and free energy changes has been explained by Marcus theory of adiabatic outer-sphere electron transfer. Disharmonic k{sub q} values for CN and CrN in endergonic region may be the disturbance of exciplexs formation. e of exciplex formation.

  5. Geometric phase and quantum interference in photosynthetic reaction center: Regulation of electron transfer

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yuming, E-mail: ymsun@ytu.edu.cn; Su, Yuehua; Dai, Zhenhong; Wang, WeiTian

    2016-10-20

    Photosynthesis is driven by electron transfer in reaction centers in which the functional unit is composed of several simple molecules C{sub 2}-symmetrically arranged into two branches. In view of quantum mechanism, both branches are possible pathways traversed by the transferred electron. Due to different evolution of spin state along two pathways in transmembrane electric potential (TEP), quantum state of the transferred electron at the bridged site acquires a geometric phase difference dependent on TEP, the most efficient electron transport takes place in a specific range of TEP beyond which electron transfer is dramatically suppressed. What’s more, reaction center acts like elaborately designed quantum device preparing polarized spin dependent on TEP for the transferred electron to regulate the reduction potential at bridged site. In brief, electron transfer generates the TEP, reversely, TEP modulates the efficiency of electron transfer. This may be an important approach to maintaining an appreciable pH environment in photosynthesis.

  6. Density and energy distribution of epithermal secondary electrons in a plasma with fast charged particles

    International Nuclear Information System (INIS)

    Jayakumar, R.; Fleischmann, H.H.

    1989-01-01

    The production of intermediate energy secondary electrons in plasmas through collisions with fast charged particles is investigated. The density and the distribution of the secondary electrons are obtained by calculating the generation, slow down and diffusion rates, using basic Rutherford collision cross sections. It is shown that the total density of secondaries is much smaller than the fast particle density and that the energy distribution has roughly a 1/√E dependence. The higher generation secondary populations are also obtained. (orig.)

  7. Fast-electron-relaxation measurement for laser-solid interaction at relativistic laser intensities

    International Nuclear Information System (INIS)

    Chen, H.; Shepherd, R.; Chung, H. K.; Kemp, A.; Hansen, S. B.; Wilks, S. C.; Ping, Y.; Widmann, K.; Fournier, K. B.; Beiersdorfer, P.; Dyer, G.; Faenov, A.; Pikuz, T.

    2007-01-01

    We present measurements of the fast-electron-relaxation time in short-pulse (0.5 ps) laser-solid interactions for laser intensities of 10 17 , 10 18 , and 10 19 W/cm 2 , using a picosecond time-resolved x-ray spectrometer and a time-integrated electron spectrometer. We find that the laser coupling to hot electrons increases as the laser intensity becomes relativistic, and that the thermalization of fast electrons occurs over time scales on the order of 10 ps at all laser intensities. The experimental data are analyzed using a combination of models that include Kα generation, collisional coupling, and plasma expansion

  8. Double ionisation of helium in fast ion collisions: the role of momentum transfer

    International Nuclear Information System (INIS)

    Bapat, B.; Moshammer, R.; Schmitt, W.; Kollmus, H.; Ullrich, J.; Doerner, R.; Weber, T.; Khayyat, K.

    1999-01-01

    Double ionisation of helium in the perturbative regime has been explored in a kinematically complete collision experiment using 100 MeV/u C 6+ ions. Different ionisation mechanisms are identified by inspecting the angular distribution of the electrons as a function of the momentum transfer q to the target by the projectile. For q 1.2 a.u., the faster electron resulting from a binary encounter with the projectile is emitted along the direction of momentum transfer, while the other electron is distributed uniformly. Experimental data are compared with various model calculations based on the Bethe-Born approximation with shake-off. Surprisingly, the effect of the final state interaction is found to depend decisively on the choice of the initial state wave function. (orig.)

  9. Charge amplification and transfer processes in the gas electron multiplier

    International Nuclear Information System (INIS)

    Bachmann, S.; Bressan, A.; Ropelewski, L.; Sauli, F.; Sharma, A.; Moermann, D.

    1999-01-01

    We report the results of systematic investigations on the operating properties of detectors based on the gas electron multiplier (GEM). The dependence of gain and charge collection efficiency on the external fields has been studied in a range of values for the hole diameter and pitch. The collection efficiency of ionization electrons into the multiplier, after an initial increase, reaches a plateau extending to higher values of drift field the larger the GEM voltage and its optical transparency. The effective gain, fraction of electrons collected by an electrode following the multiplier, increases almost linearly with the collection field, until entering a steeper parallel plate multiplication regime. The maximum effective gain attainable increases with the reduction in the hole diameter, stabilizing to a constant value at a diameter approximately corresponding to the foil thickness. Charge transfer properties appear to depend only on ratios of fields outside and within the channels, with no interaction between the external fields. With proper design, GEM detectors can be optimized to satisfy a wide range of experimental requirements: tracking of minimum ionizing particles, good electron collection with small distortions in high magnetic fields, improved multi-track resolution and strong ion feedback suppression in large volume and time-projection chambers

  10. Enzymatic cellulose oxidation is linked to lignin by long-range electron transfer

    DEFF Research Database (Denmark)

    Westereng, Bjorge; Cannella, David; Wittrup Agger, Jane

    2015-01-01

    cell walls. Electron transfer was confirmed by electron paramagnetic resonance spectroscopy showing that LPMO activity on cellulose changes the level of unpaired electrons in the lignin. The discovery of a long-range electron transfer mechanism links the biodegradation of cellulose and lignin and sheds...

  11. Electronic energy loss of fast molecules in matter

    International Nuclear Information System (INIS)

    Steinbeck, J.

    1975-06-01

    In high velocity collisions of molecular ions the correlated motion influence of the ion cores on the electronic energy loss is investigated. The stopping power in first Born approximation for a random arrangement of target atoms can be formulated in terms of the inelastic electronic structure factor. In treating the target atoms in Hartree-Fock approximation each electron can be regarded as stopping the ion independent of all other electrons without restriction by the Pauli principle. A second equivalent formulation of the stopping power leads to the dielectric function of the target. The results are applied to the stopping of H 2 + -ions. For vanishing distance between the two protons the stopping power per particle is twice that for single proton collisions. For distances in the order of the Bohr radius the correlated stopping power may even be smaller than for uncorrelated protons. With increasing distances the correlation influence vanishes. The stopping of H 2 + -ions in C, Si and Ge is discussed using Clementi wave functions for the core electrons and a free electron approximation with Lindhard's dielectric function for the valence electrons. The comparison with the only experimental result available for H 2 + in C at 300 keV yields qualitative agreement. (orig.) [de

  12. Electron Generation and Transport in Intense Relativistic Laser-Plasma Interactions Relevant to Fast Ignition ICF

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Tammy Yee Wing [Univ. of California, San Diego, CA (United States)

    2010-01-01

    The reentrant cone approach to Fast Ignition, an advanced Inertial Confinement Fusion scheme, remains one of the most attractive because of the potential to efficiently collect and guide the laser light into the cone tip and direct energetic electrons into the high density core of the fuel. However, in the presence of a preformed plasma, the laser energy is largely absorbed before it can reach the cone tip. Full scale fast ignition laser systems are envisioned to have prepulses ranging between 100 mJ to 1 J. A few of the imperative issues facing fast ignition, then, are the conversion efficiency with which the laser light is converted to hot electrons, the subsequent transport characteristics of those electrons, and requirements for maximum allowable prepulse this may put on the laser system. This dissertation examines the laser-to-fast electron conversion efficiency scaling with prepulse for cone-guided fast ignition. Work in developing an extreme ultraviolet imager diagnostic for the temperature measurements of electron-heated targets, as well as the validation of the use of a thin wire for simultaneous determination of electron number density and electron temperature will be discussed.

  13. Electronic energy transfer through non-adiabatic vibrational-electronic resonance. I. Theory for a dimer

    Science.gov (United States)

    Tiwari, Vivek; Peters, William K.; Jonas, David M.

    2017-10-01

    Non-adiabatic vibrational-electronic resonance in the excited electronic states of natural photosynthetic antennas drastically alters the adiabatic framework, in which electronic energy transfer has been conventionally studied, and suggests the possibility of exploiting non-adiabatic dynamics for directed energy transfer. Here, a generalized dimer model incorporates asymmetries between pigments, coupling to the environment, and the doubly excited state relevant for nonlinear spectroscopy. For this generalized dimer model, the vibrational tuning vector that drives energy transfer is derived and connected to decoherence between singly excited states. A correlation vector is connected to decoherence between the ground state and the doubly excited state. Optical decoherence between the ground and singly excited states involves linear combinations of the correlation and tuning vectors. Excitonic coupling modifies the tuning vector. The correlation and tuning vectors are not always orthogonal, and both can be asymmetric under pigment exchange, which affects energy transfer. For equal pigment vibrational frequencies, the nonadiabatic tuning vector becomes an anti-correlated delocalized linear combination of intramolecular vibrations of the two pigments, and the nonadiabatic energy transfer dynamics become separable. With exchange symmetry, the correlation and tuning vectors become delocalized intramolecular vibrations that are symmetric and antisymmetric under pigment exchange. Diabatic criteria for vibrational-excitonic resonance demonstrate that anti-correlated vibrations increase the range and speed of vibronically resonant energy transfer (the Golden Rule rate is a factor of 2 faster). A partial trace analysis shows that vibronic decoherence for a vibrational-excitonic resonance between two excitons is slower than their purely excitonic decoherence.

  14. Dynamical analysis on carbon transfer in liquid metal cooled fast breeder reactor

    International Nuclear Information System (INIS)

    Kataoka, Tadayuki; Matsumoto, Keishi

    1979-01-01

    The dynamical analysis was undertaken on the exchange of carbon taking place between the structural steels and sodium for the case of a bi-metallic secondary system constituted of type 304 stainless and 2 1/4Cr-1Mo steels, representing the secondary system of a liquid sodium cooled fast breeder reactor. The analysis brought to light the effects to be expected on the long terms carbon transfer behavior of: (a) the surface areas of structural steels in contact with flowing sodium, (b) the thickness of the sodium-boundary layer, (c) the initial carbon concentration in the sodium, and (d) the rate of carbon contamination of the sodium. (author)

  15. Fast algorithm for two-dimensional data table use in hydrodynamic and radiative-transfer codes

    International Nuclear Information System (INIS)

    Slattery, W.L.; Spangenberg, W.H.

    1982-01-01

    A fast algorithm for finding interpolated atomic data in irregular two-dimensional tables with differing materials is described. The algorithm is tested in a hydrodynamic/radiative transfer code and shown to be of comparable speed to interpolation in regularly spaced tables, which require no table search. The concepts presented are expected to have application in any situation with irregular vector lengths. Also, the procedures that were rejected either because they were too slow or because they involved too much assembly coding are described

  16. Competition between electronic energy transfer and relaxation in Xe doped Ar and Ne matrices studied by photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Schwentner, N.; Koch, E.E.

    1976-01-01

    Thin films of solid Ar and Ne doped with 1% Xe were excited with photons in the energy range from 10 eV to 20 eV in order to measure the energy distribution of the emitted electrons. Binding energies of th host and guest levels are deduced. When host excitons are excited, strong emission of electrons is observed indicating an efficient transfer of the host exciton energy to the Xe guest atoms. The energy of the free excitons is transferred, as can be deduced from the kinetic energy of the photoemitted electrons, rather than the energy of the bound (self-trapped) excitons which are observed in luminescence experiments. Furthermore, there is a striking difference between the Ar and the Ne matrix: In the Ne matrix a fast relaxation from the n = 2 to the n = 1 state was observed and only the energy of the n = 1 exciton is transferred even when higher excitons are excited, in contrast to Ar, where the transferred energy is higher for excitation of the n = 2 excitons than for n = 1. From these observations, time hierarchies for the competition between electronic energy transfer and relaxation are deduced. (orig.) [de

  17. Studies of Electron Transport and Isochoric Heating and Their Applicability to Fast Ignition

    International Nuclear Information System (INIS)

    Key, M H; Amiranoff, F; Andersen, C; Batani, D; Baton, S D; Cowan, T; Fisch, N; Freeman, R; Gremillet, L; Hall, T; Hatchett, S; Hill, J; King, J; Kodama, R; Koch, J; Koenig, M; Lasinski, B; Langdon, B; MacKinnon, A; Martinolli, E; Norreys, P; Parks, P; Perrelli-Cippo, E; Rabec Le Gloahec, M; Rosenbluth, M; Rousseaux, C; Santon, J J; Scianitti, F; Snavely, R; Tabak, M; Tanaka, K; Town, R; Tsutumi, T; Stephens, R

    2003-01-01

    Experimental measurements of electron transport and isochoric heating in 100 J, 1 ps laser irradiation of solid A1 targets are presented. Modeling with a hybrid PIC code is compared with the data and good agreement is obtained using a heuristic model for the electron injection. The relevance for fast ignition is discussed

  18. Lateral propagation of fast electrons at the laser-irradiated target surfaces

    International Nuclear Information System (INIS)

    Li, Y T; Lin, X X; Liu, B C; Du, F; Wang, S J; Li, C; Zhou, M L; Zhang, L; Liu, X; Wang, J; Liu, X L; Chen, L M; Wang, Z H; Ma, J L; Wei, Z Y; Zhang, J; Liu, F; Liu, F

    2010-01-01

    Lateral propagation of fast electrons at the target surfaces irradiated by femtosecond intense laser pulses is measured by k α x-ray imaging technique when a preplasma is presented. An annular halo surrounding a bright spot is observed in the x-ray images when the scale length of the electron density is large. For an incidence angle of 70 0 the x-ray images show a non-symmetrical distribution peaked to the laser propagation direction. The x-ray photons in the halo are mainly excited by the fast electrons that flow in the preplasma when their paths intersect the high density regions near the target surface.

  19. Magnetic collimation of fast electrons in specially engineered targets irradiated by ultraintense laser pulses

    International Nuclear Information System (INIS)

    Cai Hongbo; Zhu Shaoping; Wu Sizhong; Chen Mo; Zhou Cangtao; He, X. T.; Yu Wei; Nagatomo, Hideo

    2011-01-01

    The efficient magnetic collimation of fast electron flow transporting in overdense plasmas is investigated with two-dimensional collisional particle-in-cell numerical simulations. It is found that the specially engineered targets exhibiting either high-resistivity-core-low-resistivity-cladding structure or low-density-core-high-density-cladding structure can collimate fast electrons. Two main mechanisms to generate collimating magnetic fields are found. In high-resistivity-core-low-resistivity-cladding structure targets, the magnetic field at the interfaces is generated by the gradients of the resistivity and fast electron current, while in low-density-core-high-density-cladding structure targets, the magnetic field is generated by the rapid changing of the flow velocity of the background electrons in transverse direction (perpendicular to the flow velocity) caused by the density jump. The dependences of the maximal magnetic field on the incident laser intensity and plasma density, which are studied by numerical simulations, are supported by our analytical calculations.

  20. Measurements of the divergence of fast electrons in laser-irradiated spherical targets

    International Nuclear Information System (INIS)

    Yaakobi, B.; Solodov, A. A.; Myatt, J. F.; Delettrez, J. A.; Stoeckl, C.; Froula, D. H.

    2013-01-01

    In recent experiments using directly driven spherical targets on the OMEGA laser system, the energy in fast electrons was found to reach ∼1% of the laser energy at an irradiance of ∼1.1 × 10 15 W/cm 2 . The fraction of these fast electrons absorbed in the compressed fuel shell depends on their angular divergence. This paper describes measurements of this divergence deduced from a series of shots where Mo-coated shells of increasing diameter (D) were suspended within an outer CH shell. The intensity of the Mo–Kα line and the hard x-ray radiation were found to increase approximately as ∼D 2 , indicating wide divergence of the fast electrons. Alternative interpretations of these results (electron scattering, radiation excitation of Kα, and an electric field due to return current) are shown to be unimportant

  1. Role of lattice structure and low temperature resistivity in fast-electron-beam filamentation in carbon

    International Nuclear Information System (INIS)

    Dance, R J; Butler, N M H; Gray, R J; MacLellan, D A; Rusby, D R; Xu, H; Neely, D; McKenna, P; Scott, G G; Robinson, A P L; Zielbauer, B; Bagnoud, V; Desjarlais, M P

    2016-01-01

    The influence of low temperature (eV to tens-of-eV) electrical resistivity on the onset of the filamentation instability in fast-electron transport is investigated in targets comprising of layers of ordered (diamond) and disordered (vitreous) carbon. It is shown experimentally and numerically that the thickness of the disordered carbon layer influences the degree of filamentation of the fast-electron beam. Strong filamentation is produced if the thickness is of the order of 60 μm or greater, for an electron distribution driven by a sub-picosecond, mid-10 20 Wcm −2 laser pulse. It is shown that the position of the vitreous carbon layer relative to the fast-electron source (where the beam current density and background temperature are highest) does not have a strong effect because the resistive filamentation growth rate is high in disordered carbon over a wide range of temperatures up to the Spitzer regime. (paper)

  2. Exogenous electron shuttle-mediated extracellular electron transfer of Shewanella putrefaciens 200: electrochemical parameters and thermodynamics.

    Science.gov (United States)

    Wu, Yundang; Liu, Tongxu; Li, Xiaomin; Li, Fangbai

    2014-08-19

    Despite the importance of exogenous electron shuttles (ESs) in extracellular electron transfer (EET), a lack of understanding of the key properties of ESs is a concern given their different influences on EET processes. Here, the ES-mediated EET capacity of Shewanella putrefaciens 200 (SP200) was evaluated by examining the electricity generated in a microbial fuel cell. The results indicated that all the ESs substantially accelerated the current generation compared to only SP200. The current and polarization parameters were linearly correlated with both the standard redox potential (E(ES)(0)) and the electron accepting capacity (EAC) of the ESs. A thermodynamic analysis of the electron transfer from the electron donor to the electrode suggested that the EET from c-type cytochromes (c-Cyts) to ESs is a crucial step causing the differences in EET capacities among various ESs. Based on the derived equations, both E(ES)(0) and EAC can quantitatively determine potential losses (ΔE) that reflect the potential loss of the ES-mediated EET. In situ spectral kinetic analysis of ES reduction by c-Cyts in a living SP200 suspension was first investigated with the E(ES), E(c-Cyt), and ΔE values being calculated. This study can provide a comprehensive understanding of the role of ESs in EET.

  3. Electronic shift register memory based on molecular electron-transfer reactions

    Science.gov (United States)

    Hopfield, J. J.; Onuchic, Jose Nelson; Beratan, David N.

    1989-01-01

    The design of a shift register memory at the molecular level is described in detail. The memory elements are based on a chain of electron-transfer molecules incorporated on a very large scale integrated (VLSI) substrate, and the information is shifted by photoinduced electron-transfer reactions. The design requirements for such a system are discussed, and several realistic strategies for synthesizing these systems are presented. The immediate advantage of such a hybrid molecular/VLSI device would arise from the possible information storage density. The prospect of considerable savings of energy per bit processed also exists. This molecular shift register memory element design solves the conceptual problems associated with integrating molecular size components with larger (micron) size features on a chip.

  4. Layered Black Phosphorus: Strongly Anisotropic Magnetic, Electronic, and Electron-Transfer Properties.

    Science.gov (United States)

    Sofer, Zdeněk; Sedmidubský, David; Huber, Štěpán; Luxa, Jan; Bouša, Daniel; Boothroyd, Chris; Pumera, Martin

    2016-03-01

    Layered elemental materials, such as black phosphorus, exhibit unique properties originating from their highly anisotropic layered structure. The results presented herein demonstrate an anomalous anisotropy for the electrical, magnetic, and electrochemical properties of black phosphorus. It is shown that heterogeneous electron transfer from black phosphorus to outer- and inner-sphere molecular probes is highly anisotropic. The electron-transfer rates differ at the basal and edge planes. These unusual properties were interpreted by means of calculations, manifesting the metallic character of the edge planes as compared to the semiconducting properties of the basal plane. This indicates that black phosphorus belongs to a group of materials known as topological insulators. Consequently, these effects render the magnetic properties highly anisotropic, as both diamagnetic and paramagnetic behavior can be observed depending on the orientation in the magnetic field. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Bremsstrahlung of fast electrons in long air gaps

    Energy Technology Data Exchange (ETDEWEB)

    Oreshkin, E. V.; Barengolts, S. A. [P. N. Lebedev Physical Institute, RAS, 119991 Moscow (Russian Federation); General Physics Institute, RAS, 119991 Moscow (Russian Federation); Chaikovsky, S. A. [P. N. Lebedev Physical Institute, RAS, 119991 Moscow (Russian Federation); Institute of High Current Electronics, SB RAS, 634055 Tomsk (Russian Federation); Oginov, A. V.; Shpakov, K. V.; Bogachenkov, V. A. [P. N. Lebedev Physical Institute, RAS, 119991 Moscow (Russian Federation)

    2012-01-15

    The results of an experiment on discharges in long atmospheric pressure air gaps at a pulsed voltage of amplitude up to 800 kV and risetime 150-200 ns have been analyzed. In the experiment, a radiation pulse of photon energy >5 keV and duration 10-20 ns was observed. In analyzing the experimental data it was supposed that a streamer is a plasma protrusion whose surface is equipotential to the cathode surface. It has been shown that the x-ray pulse results from the switch of electrons into the mode of ''runaway'' from the head of anode-directed streamers. For the electrons injected in the electrode gap from the streamer head, conditions for their switching into the mode of continuous acceleration are realized due to the enhanced electric field at the head. The predicted maximum of the spectrum of the bremsstrahlung generated by the runaway electron beam is around 15 keV. The presence of a maximum in the bremsstrahlung spectrum is due to that the photons emitted by electrons are absorbed by atoms of the gas in which the discharge operate.

  6. Enzymatic cellulose oxidation is linked to lignin by long-range electron transfer

    DEFF Research Database (Denmark)

    Westereng, Bjorge; Cannella, David; Wittrup Agger, Jane

    2015-01-01

    in biological systems are only partly understood. We show here that insoluble high molecular weight lignin functions as a reservoir of electrons facilitating LPMO activity. The electrons are donated to the enzyme by long-range electron transfer involving soluble low molecular weight lignins present in plant...... cell walls. Electron transfer was confirmed by electron paramagnetic resonance spectroscopy showing that LPMO activity on cellulose changes the level of unpaired electrons in the lignin. The discovery of a long-range electron transfer mechanism links the biodegradation of cellulose and lignin and sheds...

  7. Magnetization Transfer Effects on the Efficiency of Flow-driven Adiabatic Fast Passage Inversion of Arterial Blood

    OpenAIRE

    Hernandez-Garcia, Luis; Lewis, David P.; Moffat, Bradford; Branch, Craig A.

    2007-01-01

    Continuous arterial spin labeling experiments typically use flow-driven adiabatic fast passage (AFP) inversion of the arterial blood water protons. In this article, we measure the effect of magnetization transfer in blood and how it affects the inversion label. We use modified Bloch equations to model flow-driven adiabatic inversion in the presence of magnetization transfer in blood flowing at velocities from 1 to 30 cm/s in order to explain our findings. Magnetization transfer results in a r...

  8. Electron transfer flavoprotein deficiency: Functional and molecular aspects

    DEFF Research Database (Denmark)

    Schiff, M; Froissart, R; Olsen, Rikke Katrine Jentoft

    2006-01-01

    Multiple acyl-CoA dehydrogenase deficiency (MADD) is a recessively inherited metabolic disorder that can be due to a deficiency of electron transfer flavoprotein (ETF) or its dehydrogenase (ETF-ubiquinone oxidoreductase). ETF is a mitochondrial matrix protein consisting of alpha- (30kDa) and beta......- (28kDa) subunits encoded by the ETFA and ETFB genes, respectively. In the present study, we have analysed tissue samples from 16 unrelated patients with ETF deficiency, and we report the results of ETF activity, Western blot analysis and mutation analysis. The ETF assay provides a reliable diagnostic...... tool to confirm ETF deficiency in patients suspected to suffer from MADD. Activity ranged from less than 1 to 16% of controls with the most severely affected patients disclosing the lowest activity values. The majority of patients had mutations in the ETFA gene while only two of them harboured...

  9. Facile direct electron transfer in glucose oxidase modified electrodes

    International Nuclear Information System (INIS)

    Wang Dan; Chen Liwei

    2009-01-01

    Glucose oxidase (GOx) is widely used in the glucose biosensor industry. However, mediatorless direct electron transfer (DET) from GOx to electrode surfaces is very slow. Recently, mediatorless DET has been reported via the incorporation of nanomaterials such as carbon nanotubes and nanoparticles in the modification of electrodes. Here we report GOx electrodes showing DET without the need for any nanomaterials. The enzyme after immobilization with poly-L-lysine (PLL) and Nafion retains the biocatalytic activities and oxidizes glucose efficiently. The amperometric response of Nafion-PLL-GOx modified electrode is linearly proportional to the concentration of glucose up to 10 mM with a sensitivity of 0.75 μA/mM at a low detection potential (-0.460 V vs. Ag/AgCl). The methodology developed in this study will have impact on glucose biosensors and biofuel cells and may potentially simplify enzyme immobilization in other biosensing systems.

  10. Radiolytic and electron-transfer reactions in supercritical CO2

    International Nuclear Information System (INIS)

    Bartels, D. M.; Dimitrijevic, N. M.; Jonah, C. D.; Takahashi, K.

    2000-01-01

    Using supercritical fluids as solvents is useful for both practical and theoretical reasons. It has been proposed to use supercritical CO 2 as a solvent for synthesis because it eliminates the air pollution arising from other solvents. The properties of supercritical fluids can be easily varied with only modest changes in temperature and density, so they provide a way of testing theories of chemical reactions. It has also been proposed to use supercritical fluids for the treatment of hazardous mixed waste. For these reasons the authors have studied the production of radiolytic species in supercritical CO 2 and have measured their reactivity as a function of density. They have shown that the C 2 O 4 + is formed. They also have shown that the electron transfer reactions of dimethylaniline to C 2 O 4 + and CO 2 (e - ) to benzoquinone are diffusion controlled over a considerable density range

  11. Bond charges and electronic charge transfer in ternary semiconductors

    International Nuclear Information System (INIS)

    Pietsch, U.

    1986-01-01

    By means of a simple molecule-theoretic model of 'linear superposition of two-electron molecules' the bond charges between nearest neighbours and the effective charges of ions are calculated for ternary zinc-blende structure alloys as well as chalcopyrite semiconductors. Taking into account both, the charge transfer among the ions caused by the differences of electronegativities of atoms used and between the bonds created by the internal stress of the lattice a nearly unvaried averaged bond charge amount of the alloy is found, but rather dramatically changed local bond charge parameters in comparison with the respective values of binary compounds used. This fact should influence the noncentral force interaction in such semiconductors. (author)

  12. Electron transfer reactions to probe the electrode/solution interface

    Energy Technology Data Exchange (ETDEWEB)

    Capitanio, F.; Guerrini, E.; Colombo, A.; Trasatti, S. [Milan Univ., Milan (Italy). Dept. of Physical Chemistry and Electrochemistry

    2008-07-01

    The reactions that occur at the interface between an electrode and an electrolyte were examined with particular reference to the interaction of different electrode surfaces with redox couples. A semi-integration or convolution technique was used to study the kinetics of electron transfer on different electrode materials with different hydrophilic behaviour, such as Boron-Doped-Diamond (BDD), Au and Pt. Standard reversible redox couples were also investigated, including (Fe3+/2+, Fe(CN)63-/4-, Ru(NH3)63+/2+, Co(NH3)63+/2+, Ir4+/3+, V4+/5+ and V3+/2+). The proposed method proved to be simple, straightforward and reliable since the obtained kinetic information was in good agreement with data in the literature. It was concluded that the kinetics of the electrode transfer reactions depend on the chemical nature of the redox couple and electrode material. The method should be further extended to irreversible couples and other electrode materials such as mixed oxide electrodes. 3 refs., 2 figs.

  13. Kinetic Theory and Fast Wind Observations of the Electron Strahl

    Science.gov (United States)

    Horaites, Konstantinos; Boldyrev, Stanislav; Wilson, Lynn B., III; Viñas, Adolfo F.; Merka, Jan

    2018-02-01

    We develop a model for the strahl population in the solar wind - a narrow, low-density and high-energy electron beam centred on the magnetic field direction. Our model is based on the solution of the electron drift-kinetic equation at heliospheric distances where the plasma density, temperature and the magnetic field strength decline as power laws of the distance along a magnetic flux tube. Our solution for the strahl depends on a number of parameters that, in the absence of the analytic solution for the full electron velocity distribution function (eVDF), cannot be derived from the theory. We however demonstrate that these parameters can be efficiently found from matching our solution with observations of the eVDF made by the Wind satellite's SWE strahl detector. The model is successful at predicting the angular width (FWHM) of the strahl for the Wind data at 1 au, in particular by predicting how this width scales with particle energy and background density. We find that the strahl distribution is largely determined by the local temperature Knudsen number γ ∼ |T dT/dx|/n, which parametrizes solar wind collisionality. We compute averaged strahl distributions for typical Knudsen numbers observed in the solar wind, and fit our model to these data. The model can be matched quite closely to the eVDFs at 1 au; however, it then overestimates the strahl amplitude at larger heliocentric distances. This indicates that our model may be improved through the inclusion of additional physics, possibly through the introduction of 'anomalous diffusion' of the strahl electrons.

  14. Fast electron current density profile and diffusion studies during LHCD in PBX-M

    International Nuclear Information System (INIS)

    Jones, S.E.; Kesner, J.; Luckhardt, S.; Paoletti, F.

    1993-08-01

    Successful current profile control experiments using lower hybrid current drive (LCHD) clearly require knowledge of (1) the location of the driven fast electrons and (2) the ability to maintain that location from spreading due to radial diffusion. These issues can be addressed by examining the data from the hard x-ray camera on PBX-M, a unique diagnostic producing two-dimensional, time resolved tangential images of fast electron bremsstrahlung. Using modeling, these line-of-sight images are inverted to extract a radial fast electron current density profile. We note that ''hollow'' profiles have been observed, indicative of off-axis current drive. These profiles can then be used to calculate an upper bound for an effective fast electron diffusion constant: assuming an extremely radially narrow lower hybrid absorption profile and a transport model based on Rax and Moreau, a model fast electron current density profile is calculated and compared to the experimentally derived profile. The model diffusion constant is adjusted until a good match is found. Applied to steady-state quiescent modes on PBX-M, we obtain an upper limit for an effective diffusion constant of about D*=1.1 m 2 /sec

  15. Effects of buried high-Z layers on fast electron propagation

    International Nuclear Information System (INIS)

    Yang, Xiaohu; Zhuo, Hongbin; Ma, Yanyun; Shao, Fuqiu; Xu, Han; Yin Yan; Borghesi, M.

    2014-01-01

    The transport through high density plasmas of relativistic electron beams generated by ultra-intense laser-plasma interaction has potential applications in laser-driven ion acceleration and in the fast igniter scheme for inertial confinement fusion. By extending a prior model [A.R. Bell, J.R. Davies, S.M. Guerin, Phys. Rev. E 58, 2471 (1998)], the magnetic field generated during the transport of a fast electron beam driven by an ultra-intense laser in a solid target is derived analytically and applied to estimate the effect of such field on fast electron propagation through a buried high-Z layer in a lower-Z target. It is found that the effect gets weaker with the increase of the depth of the buried layer, the divergence of the fast electrons, and the laser intensity, indicating that magnetic field effects on the fast electron divergence as measured from K a X-ray emission may need to be considered for moderate laser intensities. On the basis of the calculations, some considerations are made on how one can mitigate the effect of the magnetic field generated at the interface. (authors)

  16. Thin films of amorphous nitrogenated carbon a-CN{sub x}: Electron transfer and surface reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Tamiasso-Martinhon, P.; Cachet, H.; Debiemme-Chouvy, C.; Deslouis, C. [Universite Pierre et Marie Curie-Paris 6, Laboratoire Interfaces et Systemes Electrochimiques, CNRS, UPR15-LISE, 4 Place Jussieu, Paris F-75005 (France)

    2008-08-01

    The electrochemical behaviour of thin films of nitrogenated amorphous carbon a-CN{sub x} is similar to that of boron-doped diamond, with a wide potential window in aqueous media. They are elaborated by cathodic sputtering of a graphite target in an Ar-N{sub 2} active plasma for varying nitrogen contents, determined by XPS (0.06 {<=} x {<=} 0.39). Their electrochemical reactivity is sensitive to the surface state. The present study reports on the influence of electrochemical pre treatment on the electronic transfer rate of a fast redox system ferri-ferrocyanide, by focusing on the direction of the potential excursion. On the other hand, the role of both the pH and the potential on the interfacial capacitance in the presence of Na{sub 2}SO{sub 4} without redox species is documented. The results show up the sensitivity of the film surface to the electrochemical conditions. (author)

  17. Transformation of methano[60]fullerenes in dihydrofullerofuranes induced by electron transfer

    International Nuclear Information System (INIS)

    Yanilkin, V.V.; Toropchina, A.V.; Morozov, V.I.; Nastapova, N.V.; Gubskaya, V.P.; Sibgatullina, F.G.; Azancheev, N.M.; Efremov, Yu.Ya.; Nuretdinov, I.A.

    2004-01-01

    The electrochemical reduction of methano[60]fullerenes (61-acetyl-61-(diethoxyphosphoryl)methano-60-fullerene 1, 61-acetyl-61-(diisopropoxyphosphoryl)methano-60-fullerene 2, 61-(2,2-diethoxyacetyl)-61-(diethoxy-phosphoryl)methano-60-fullerene 3, 61-phenyl-61-(1,2-dioxo-3,3-dimethyl-buthyl)methano-60-fullerene 4) in o-dichlorobenzene-DMF (3:1 v/v)/0.1 M Bu 4 NBF 4 on a glass-carbon electrode proceeds in a few steps. The reversible transfer of the first electron results in the formation of radical anions registered by ESR method. The subsequent reduction proceeds differently because of the various stability of anionic intermediates. The radical anions of the methanofullerenes 3 and 4 are less stable than the radical anions of compounds 1 and 2 and less stable than the radical anions of methanofullerenes, which contain an ester and/or a phosphonate group. The opening of a cyclopropane ring occurs during the stage of the formation of radical trianions of methanofullerenes 1, 2. The same process for compounds 3, 4 proceeds slowly in radical anions and fast in dianions. The opening of cyclopropane ring for all compounds is not accompanied by the elimination of methanogroup and results in the formation of dihydrofullerenofurane derivatives. The transformation of methanofullerene 3 induced by single electron transfer proceeds via a chain reaction mechanism

  18. A note on the standard electron transfer potential at the interface between two immiscible electrolyte solutions

    Czech Academy of Sciences Publication Activity Database

    Samec, Zdeněk

    2009-01-01

    Roč. 55, č. 2 (2009), s. 75-81 ISSN 0034-6691 R&D Projects: GA ČR(CZ) GA203/07/1257 Institutional research plan: CEZ:AV0Z40400503 Keywords : interface between two immiscible electrolyte solutions * interfacial electron transfer * standard electron trasfer potential * homogeneous electron transfer Subject RIV: CG - Electrochemistry

  19. Ab initio study on electron excitation and electron transfer in tryptophan-tyrosine system

    International Nuclear Information System (INIS)

    Tong Jing; Li Xiangyuan

    2002-01-01

    In this article, ab initio calculation has been performed to evaluate the transition energy of electronic excitation in tryptophan and tyrosine by using semiempirical molecular orbital method AM1 and complete active space self-consistent field method. The solvent effect has been considered by means of the conductor-like screening model. After geometric optimizations of isolated tryptophan and tyrosine, and their corresponding radicals and cations, reaction heat of these electron transfer reactions have been obtained by the means of complete active space self-consistent field method. The transition energies from the ground state, respectively, to the lowest excited state and to the lowest triplet state of these two amino acids are also calculated and compared with the experimentally observed values. The ionization potential and electron affinity are also calculated for tryptophan and tyrosine employing Koopmans' theorem and ab initio calculation. Compared with the experimental measurements, the theoretical results are found satisfactory. Theoretical results give good explanations on the experimental phenomena that N 3 · can preferably oxide the side chain of tryptophan residue and then the electron transfer from tyrosine residue to tryptophan residue follows in peptides involving tryptophan and tyrosine

  20. Transfer of spectral weight in spectroscopies of correlated electron systems

    International Nuclear Information System (INIS)

    Rozenberg, M.J.; Kotliar, G.; Kajueter, H.

    1996-01-01

    We study the transfer of spectral weight in the photoemission and optical spectra of strongly correlated electron systems. Within the local impurity self-consistent approximation, that becomes exact in the limit of large lattice coordination, we consider and compare two models of correlated electrons, the Hubbard model and the periodic Anderson model. The results are discussed in regard to recent experiments. In the Hubbard model, we predict an anomalous enhancement optical spectral weight as a function of temperature in the correlated metallic state which is in qualitative agreement with optical measurements in V 2 O 3 . We argue that anomalies observed in the spectroscopy of the metal are connected to the proximity to a crossover region in the phase diagram of the model. In the insulating phase, we obtain excellent agreement with the experimental data, and present a detailed discussion on the role of magnetic frustration by studying the k-resolved single-particle spectra. The results for the periodic Anderson model are discussed in connection to recent experimental data of the Kondo insulators Ce 3 Bi 4 Pt 3 and FeSi. The model can successfully explain the thermal filling of the optical gap and the corresponding changes in the photoemission density of states. The temperature dependence of the optical sum rule is obtained, and its relevance to the interpretation of the experimental data discussed. Finally, we argue that the large scattering rate measured in Kondo insulators cannot be described by the periodic Anderson model. copyright 1996 The American Physical Society

  1. Magnetic-field generation and electron-collimation analysis for propagating fast electron beams in overdense plasmas

    International Nuclear Information System (INIS)

    Cai Hongbo; Zhu Shaoping; Chen Mo; Wu Sizhong; He, X. T.; Mima, Kunioki

    2011-01-01

    An analytical fluid model is proposed for artificially collimating fast electron beams produced in the interaction of ultraintense laser pulses with specially engineered low-density-core-high-density-cladding structure targets. Since this theory clearly predicts the characteristics of the spontaneously generated magnetic field and its dependence on the plasma parameters of the targets transporting fast electrons, it is of substantial relevance to the target design for fast ignition. The theory also reveals that the rapid changing of the flow velocity of the background electrons in a transverse direction (perpendicular to the flow velocity) caused by the density jump dominates the generation of a spontaneous interface magnetic field for these kinds of targets. It is found that the spontaneously generated magnetic field reaches as high as 100 MG, which is large enough to collimate fast electron transport in overdense plasmas. This theory is also supported by numerical simulations performed using a two-dimensional particle-in-cell code. It is found that the simulation results agree well with the theoretical analysis.

  2. Challenges of Remote Sensing and Spatial Information Education and Technology Transfer in a Fast Developing Industry

    Science.gov (United States)

    Tsai, F.; Chen, L.-C.

    2014-04-01

    During the past decade, Taiwan has experienced an unusual and fast growing in the industry of mapping, remote sensing, spatial information and related markets. A successful space program and dozens of advanced airborne and ground-based remote sensing instruments as well as mobile mapping systems have been implemented and put into operation to support the vast demands of geospatial data acquisition. Moreover, in addition to the government agencies and research institutes, there are also tens of companies in the private sector providing geo-spatial data and services. However, the fast developing industry is also posing a great challenge to the education sector in Taiwan, especially the higher education for geo-spatial information. Facing this fast developing industry, the demands of skilled professionals and new technologies in order to address diversified needs are indubitably high. Consequently, while delighting in the expanding and prospering benefitted from the fast growing industry, how to fulfill these demands has become a challenge for the remote sensing and spatial information disciplines in the higher education institutes in Taiwan. This paper provides a brief insight into the status of the remote sensing and spatial information industry in Taiwan as well as the challenges of the education and technology transfer to support the increasing demands and to ensure the continuous development of the industry. In addition to the report of the current status of the remote sensing and spatial information related courses and programs in the colleges and universities, current and potential threatening issues and possible resolutions are also discussed in different points of view.

  3. Enhanced coupling of the fast wave to electrons through mode conversion to the ion hybrid wave

    International Nuclear Information System (INIS)

    Lashmore-Davies, C.N.; Fuchs, V.; Ram, A.K.; Bers, A.

    1996-07-01

    The mode conversion of the fast compressional Alfven wave to the ion hybrid wave is analyzed with particular reference to a plasma with two ion species present in approximately equal proportions. Two configurations are considered, the first referring to the usual resonance-cut-off case and the second to a cut-off-resonance-cut-off situation. The optimum conditions for maximising the mode converted energy are given. The second order fast wave equation is generalised to include the effect of the parallel electric field. Hence, all ion and electron loss mechanisms for the fast wave are incorporated, including mode conversion at the two-ion hybrid resonance. The significance of the approximate equality of the two ion species concentrations is that the mode converted ion hybrid wave is damped only by the electrons. The damping of the ion hybrid wave is described with the aid of the local dispersion relation and by means of a toroidal ray tracing code. In particular, the ray tracing calculation shows that the mode converted energy is totally absorbed by the electrons close to the two-ion hybrid resonance. The generalised fast wave equation is solved to determine how much energy is lost from the fast wave, incident from the low field side, before it encounters the two-ion hybrid resonance. For comparable concentrations of the two ion species, the mode converted power can be separated from the power directly absorbed by the ions and electrons from the fast wave. This allows the conditions to be ascertained under which strong electron heating through mode conversion dominates the direct dissipation of the fast wave. (UK)

  4. Correlation properties of surface and percolation transfer of electrons

    International Nuclear Information System (INIS)

    Bakunin, O.G.

    2002-01-01

    In this work was received equation, connecting correlatively properties of surface with electrons distribution function. Usually for equilibrium is necessary a large number of collisions. Collisions are 'destroying' correlations. In case rare collisions large importance have correlations and 'memory' effects. Non-Markov's character of emitting particles by surface lead to strongly nonequilibrium condition of 'gas'. Here kinetic equation of diffusive form does not apply. Classical kinetic equation are described only conditions near to equilibrium. This work offers to use ideas anomal diffusion in phase-space. The correlation properties of surface describe by correlations of velocities of emitting electrons: B(t). We offer to use functional equation for probability collision instead of kinetic equation: ∫ 0 ν 0 W noncoll F(ν) dv = 1 - B(t). This functional allow to consider 'memory' effects. It is important for consideration of electrons and clusters near surfaces. Distribution function become direct connected with correlations. In classical Kubo-Mory theory of transfer is necessary to get nondivergences integral: D ∝ ∫ 0 ∞ B(t). In considering case we can use even 'power function'. It was used 'slow' correlation function as Kohlraush in calculations. The information about kinetics and correlations properties are containing in one functional equation. It was received solution of this equation in form Levy function: F(ν) ∝ 1/ν α exp(-1/ν). The solution of this form can not be get with help asymptotic methods of kinetic theory. Asymptotics of solution have scale-invariant character F(V) ∝ 1/V α . This indicate on fractal properties phase-space. (author)

  5. Allosteric control of internal electron transfer in cytochrome cd1 nitrite reductase

    DEFF Research Database (Denmark)

    Farver, Ole; Kroneck, Peter M H; Zumft, Walter G

    2003-01-01

    Cytochrome cd1 nitrite reductase is a bifunctional multiheme enzyme catalyzing the one-electron reduction of nitrite to nitric oxide and the four-electron reduction of dioxygen to water. Kinetics and thermodynamics of the internal electron transfer process in the Pseudomonas stutzeri enzyme have...... been studied and found to be dominated by pronounced interactions between the c and the d1 hemes. The interactions are expressed both in dramatic changes in the internal electron-transfer rates between these sites and in marked cooperativity in their electron affinity. The results constitute a prime...... example of intraprotein control of the electron-transfer rates by allosteric interactions....

  6. 77 FR 6310 - Electronic Fund Transfers (Regulation E)

    Science.gov (United States)

    2012-02-07

    ... business'' in the definition of ``remittance transfer provider.'' This definition determines whether a... remittance transfers in the ``normal course of its business'' from the definition of ``remittance transfer... ``normal course of business'' for purposes of the definition of ``remittance transfer provider.'' Second...

  7. Fast Electron Repulsion Integrals for Molecular Coulomb Sturmians

    DEFF Research Database (Denmark)

    Avery, James Emil

    2013-01-01

    A new method is presented for calculating interelectron repulsion integrals for molecular Coulomb Sturmian basis sets. This makes use of an expansion of densities in terms of 2k-Sturmians, and the interelectron repulsion integrals are then calculated by a method based on the theory of hyperspheri......A new method is presented for calculating interelectron repulsion integrals for molecular Coulomb Sturmian basis sets. This makes use of an expansion of densities in terms of 2k-Sturmians, and the interelectron repulsion integrals are then calculated by a method based on the theory...... of hyperspherical harmonics. A rudimentary software library has been implemented and preliminary benchmarks indicate very good performance: On average 40 ns, or approximately 80 clock cycles, per electron repulsion integral. This makes molecular Coulomb Sturmians competitive with Gaussian type orbitals in terms...

  8. Dose measurement of fast electrons with a modified Fricke solution

    International Nuclear Information System (INIS)

    Nemec, H.W.; Roth, J.; Luethy, H.

    1975-01-01

    A combination of two different modifications indicated in the literature about the ferrosulfate dosimetry is given. This permits a dose measurement which shows compared to the usual Fricke dosimetry above all following advantages: dose specification related to water; displacement of the absorption maximum in the perceptible spectral sphere; increase of the sensibility and lower influence of pollutions. The molar coefficient of extinction of the modified solution has been determined from 60 Co gamma irradiation and is epsilonsub(m) = 1.46 x 10 4 l x Mol -1 x cm -1 . The increase of extinction which has been measured with this method after the irradiation with 18 MeV electrons occurs linearly within the studied region to 1,200 rd at least, the G-value is 15.5. The indicated method renders possible a relative simple calibration of the ionization chambers used in the practice. (orig.) [de

  9. Control of Electron Transfer from Lead-Salt Nanocrystals to TiO 2

    KAUST Repository

    Hyun, Byung-Ryool

    2011-05-11

    The roles of solvent reorganization energy and electronic coupling strength on the transfer of photoexcited electrons from PbS nanocrystals to TiO 2 nanoparticles are investigated. We find that the electron transfer depends only weakly on the solvent, in contrast to the strong dependence in the nanocrystal-molecule system. This is ascribed to the larger size of the acceptor in this system, and is accounted for by Marcus theory. The electronic coupling of the PbS and TiO 2 is varied by changing the length, aliphatic and aromatic structure, and anchor groups of the linker molecules. Shorter linker molecules consistently lead to faster electron transfer. Surprisingly, linker molecules of the same length but distinct chemical structures yield similar electron transfer rates. In contrast, the electron transfer rate can vary dramatically with different anchor groups. © 2011 American Chemical Society.

  10. Hydrated Electron Transfer to Nucleobases in Aqueous Solutions Revealed by Ab Initio Molecular Dynamics Simulations.

    Science.gov (United States)

    Zhao, Jing; Wang, Mei; Fu, Aiyun; Yang, Hongfang; Bu, Yuxiang

    2015-08-03

    We present an ab initio molecular dynamics (AIMD) simulation study into the transfer dynamics of an excess electron from its cavity-shaped hydrated electron state to a hydrated nucleobase (NB)-bound state. In contrast to the traditional view that electron localization at NBs (G/A/C/T), which is the first step for electron-induced DNA damage, is related only to dry or prehydrated electrons, and a fully hydrated electron no longer transfers to NBs, our AIMD simulations indicate that a fully hydrated electron can still transfer to NBs. We monitored the transfer dynamics of fully hydrated electrons towards hydrated NBs in aqueous solutions by using AIMD simulations and found that due to solution-structure fluctuation and attraction of NBs, a fully hydrated electron can transfer to a NB gradually over time. Concurrently, the hydrated electron cavity gradually reorganizes, distorts, and even breaks. The transfer could be completed in about 120-200 fs in four aqueous NB solutions, depending on the electron-binding ability of hydrated NBs and the structural fluctuation of the solution. The transferring electron resides in the π*-type lowest unoccupied molecular orbital of the NB, which leads to a hydrated NB anion. Clearly, the observed transfer of hydrated electrons can be attributed to the strong electron-binding ability of hydrated NBs over the hydrated electron cavity, which is the driving force, and the transfer dynamics is structure-fluctuation controlled. This work provides new insights into the evolution dynamics of hydrated electrons and provides some helpful information for understanding the DNA-damage mechanism in solution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Study of fast electrons from hard-X radiation; Etude des electrons rapides a partir du rayonnement X-dur

    Energy Technology Data Exchange (ETDEWEB)

    Arslanbekov, R.

    1995-12-19

    The goal of this thesis is the study of fast electron dynamics by means of the hard X-ray diagnosis installed in TORE SUPRA and numerical simulations. Fast electrons are generated in the plasma in the presence of the injected lower hybrid (LH) waves. Two aspects are studied in detail: the lower hybrid wave propagation and absorption in a periodically perturbed media and 2-D Fokker-Planck modelling of the fast electron dynamics in the presence of the LH power. Ripple effects on lower hybrid wave propagation and absorption are investigated using the ray tracing technique. A cylindrical equilibrium is first studied and a strong modification of the ray dynamics is predicted. Calculations are carried out in a real toroidal geometry corresponding to TORE SUPRA. It is shown that the lack of toroidal axisymmetry of the magnetic field may result in a modification of the ray evolution even if the global ray evolution is governed by the larger poloidal inhomogeneity. Simulation of LH experiments are performed for TORE SUPRA tokamak which has a large magnetic ripple (7% at the plasma edge). By considering ripple perturbation in LH current drive simulations, a better agreement is found with experimental results, in particular with the hard-X spectra and the current density profiles. In the second part of the thesis, a 2-D modeling of the fast electron dynamics in the velocity phase space is considered, based on the 2-D relativistic electron Fokker-Planck equation. Electron distribution functions obtained are used to calculate non-thermal Bremsstrahlung emission for different TORE SUPRA shots in a wide range of experimental conditions. (J.S.). 168 refs., 93 figs., 1 tab., 3 appendix.

  12. Type IV pili of Acidithiobacillus ferrooxidans can transfer electrons from extracellular electron donors.

    Science.gov (United States)

    Li, Yongquan; Li, Hongyu

    2014-03-01

    Studies on Acidithiobacillus ferrooxidans accepting electrons from Fe(II) have previously focused on cytochrome c. However, we have discovered that, besides cytochrome c, type IV pili (Tfp) can transfer electrons. Here, we report conduction by Tfp of A. ferrooxidans analyzed with a conducting-probe atomic force microscope (AFM). The results indicate that the Tfp of A. ferrooxidans are highly conductive. The genome sequence of A. ferrooxidans ATCC 23270 contains two genes, pilV and pilW, which code for pilin domain proteins with the conserved amino acids characteristic of Tfp. Multiple alignment analysis of the PilV and PilW (pilin) proteins indicated that pilV is the adhesin gene while pilW codes for the major protein element of Tfp. The likely function of Tfp is to complete the circuit between the cell surface and Fe(II) oxides. These results indicate that Tfp of A. ferrooxidans might serve as biological nanowires transferring electrons from the surface of Fe(II) oxides to the cell surface. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. The practical model of electron emission in the radioisotope battery by fast ions

    International Nuclear Information System (INIS)

    Erokhine, N.S.; Balebanov, V.M.

    2003-01-01

    Under the theoretical analysis of secondary-emission radioisotope source of current the estimate of energy spectrum F(E) of secondary electrons with energy E emitted from films is the important problem. This characteristic knowledge allows, in particular, studying the volt-ampere function, the dependence of electric power deposited in the load on the system parameters and so on. Since the rigorous calculations of energy spectrum F(E) are the complicated enough and labour-intensive there is necessity to elaborate the practical model which allows by the simple computer routine on the basis of generalized data (both experimental measurements and theoretical calculations) on the stopping powers and mean free path of suprathermal electrons to perform reliable express-estimates of the energy spectrum F(E) and the volt-ampere function I(V) for the concrete materials of battery emitter films. This paper devoted to description of of the practical model to calculate electron emission characteristics under the passage of fast ion fluxes from the radioisotope source through the battery emitter. The analytical approximations for the stopping power of emitter materials, the electron inelastic mean free path, the ion production of fast electrons and the probability for them to arrive the film surface are taken into account. In the cases of copper and gold films, the secondary electron escaping depth, the position of energy spectrum peak are considered in the dependence on surface potential barrier magnitude U. According to our calculations the energy spectrum peak shifted to higher electron energy under the U growth. The model described may be used for express estimates and computer simulations of fast alpha-particles and suprathermal electrons interactions with the solid state plasma of battery emitter films, to study the electron emission layer characteristics including the secondary electron escaping depth, to find the optimum conditions for excitation of nonequilibrium

  14. Quantitative comparisons of type III radio burst intensity and fast electron flux at 1 AU

    Science.gov (United States)

    Fitzenreiter, R. J.; Evans, L. G.; Lin, R. P.

    1976-01-01

    We compare the flux of fast solar electrons and the intensity of the type III radio emission generated by these particles at 1 AU. We find that there are two regimes in the generation of type III radiation: one where the radio intensity is linearly proportional to the electron flux, and the second regime, which occurs above a threshold electron flux, where the radio intensity is proportional to the approximately 2.4 power of the electron flux. This threshold appears to reflect a transition to a different emission mechanism.

  15. Quantitative comparisons of type 3 radio burst intensity and fast electron flux at 1 AU

    Science.gov (United States)

    Fitzenreiter, R. J.; Evans, L. G.; Lin, R. P.

    1975-01-01

    The flux of fast solar electrons and the intensity of the type 111 radio emission generated by these particles were compared at one AU. Two regimes were found in the generation of type 111 radiation: one where the radio intensity is linearly proportional to the electron flux, and another, which occurs above a threshold electron flux, where the radio intensity is approximately proportional to the 2.4 power of the electron flux. This threshold appears to reflect a transition to a different emission mechanism.

  16. Quantitative comparisons of type 3 radio burst intensity and fast electron flux at 1 AU

    International Nuclear Information System (INIS)

    Fitzenreiter, R.J.; Evans, L.G.; Lin, R.P.

    1975-09-01

    The flux of fast solar electrons and the intensity of the type-III radio emission generated by these particles were compared at one AU. Two regimes were found in the generation of type-III radiation: one, where the radio intensity is linearly proportional to the electron flux, and another, which occurs above a threshold electron flux, where the radio intensity is approximately proportional to the 2.4 power of the electron flux. This threshold appears to reflect a transition to a different emission mechanism

  17. Fast electron flow formation in the AMBAL-M open trap device

    International Nuclear Information System (INIS)

    Taskaev, S.Yu.

    2000-01-01

    Hot target plasma is obtained and essential longitudinal electron current passing in plasma from the source to a plasma tube is detected experimentally in the limit magnetic mirror of AMBAL-M facility using the end gas-discharge source of plasma. The flow of the electron current in front of the inlet plug where the longitudinal electrical field is directed away from the plug is studied various models of plasma description and possibilities of instability progress are studied. The essential longitudinal electron current in electron accelerating electrical field is shown the lead to the formation of fast neutron flux conveying current in a magnetic mirror [ru

  18. Role and Potential of Direct Interspecies Electron Transfer in Anaerobic Digestion

    Directory of Open Access Journals (Sweden)

    Gahyun Baek

    2018-01-01

    Full Text Available Anaerobic digestion (AD is an effective biological treatment for stabilizing organic compounds in waste/wastewater and in simultaneously producing biogas. However, it is often limited by the slow reaction rates of different microorganisms’ syntrophic biological metabolisms. Stable and fast interspecies electron transfer (IET between volatile fatty acid-oxidizing bacteria and hydrogenotrophic methanogens is crucial for efficient methanogenesis. In this syntrophic interaction, electrons are exchanged via redox mediators such as hydrogen and formate. Recently, direct IET (DIET has been revealed as an important IET route for AD. Microorganisms undergoing DIET form interspecies electrical connections via membrane-associated cytochromes and conductive pili; thus, redox mediators are not required for electron exchange. This indicates that DIET is more thermodynamically favorable than indirect IET. Recent studies have shown that conductive materials (e.g., iron oxides, activated carbon, biochar, and carbon fibers can mediate direct electrical connections for DIET. Microorganisms attach to conductive materials’ surfaces or vice versa according to particle size, and form conductive biofilms or aggregates. Different conductive materials promote DIET and improve AD performance in digesters treating different feedstocks, potentially suggesting a new approach to enhancing AD performance. This review discusses the role and potential of DIET in methanogenic systems, especially with conductive materials for promoting DIET.

  19. NO-γ emissions from streamer discharges: direct electron impact excitation versus resonant energy transfer

    International Nuclear Information System (INIS)

    Liu Ningyu; Pasko, Victor P

    2010-01-01

    It has been established that production of NO-γ emission in pulsed corona discharges is dominated by the energy transfer from N 2 (A 3 Σ u + ) to the NO ground state NO(X 2 Π r ) while direct excitation by electron impact is negligible. However, recent studies suggest that the electron impact excitation plays a more important role. In this work, we report modelling results of NO-γ emission associated with streamer discharges using two cross section data sets available in the literature. The first set was originally reported by Mojarrabi et al (1996 Phys. Rev. A 54 2977-82) and later updated by Brunger et al (2000 J. Phys. B: At. Mol. Opt. Phys. 33 809-19); the second set was published by Hayashi (1990 Nonequilibrium Processes in Partially Ionized Gases (NATO Advanced Science Institutes Series, Series B, Physics vol 220) ed M Capitelli and J N Bardsley (New York: Plenum) pp 333-40). According to the results, the role played by the electron impact excitation in the production of NO-γ is drastically different when different cross sections are used. The results indicate that the first data set leads to better agreement with experimental measurements. (fast track communication)

  20. Electron transfer reactions of macrocyclic compounds of cobalt

    Energy Technology Data Exchange (ETDEWEB)

    Heckman, R.A.

    1978-08-01

    The kinetics and mechanisms of reduction of H/sub 2/O/sub 2/, Br/sub 2/, and I/sub 2/ by various macrocyclic tetraaza complexes of cobalt(II), including Vitamin B/sub 12r/, were studied. The synthetic macrocycles studied were all 14-membered rings which varied in the degree of unsaturation,substitution of methyl groups on the periphery of the ring, and substitution within the ring itself. Scavenging experiments demonstrated that the reductions of H/sub 2/O/sub 2/ produce free hydroxyl radicals only in the case of Co((14)ane)/sup 2 +/ but with none of the others. In the latter instances apparently H/sub 2/O/sub 2/ simultaneously oxidizes the metal center and the ligand. The reductions of Br/sub 2/ and I/sub 2/ produce an aquohalocobalt(III) product for all reductants (except B/sub 12r/ + Br/sub 2/, which was complicated by bromination of the corrin ring). The mechanism of halogen reduction was found to involve rate-limiting inner-sphere electron transfer from cobalt to halogen to produce a dihalide anion coordinated to the cobalt center. This intermediate subsequently decomposes in rapid reactions to halocobalt(III) and halogen atom species or reacts with another cobalt(II) center to give two molecules of halocobalt(III). The reductions of halomethylcobaloximes and related compounds and diamminecobaloxime by Cr/sup 2 +/ were also studied. The reaction was found to be biphasic in all cases with the reaction products being halomethane (for the halomethylcobaloximes), Co/sup 2 +/ (in less than 100 percent yield), a Cr(III)-dimethylglyoxime species, a small amount of free dmgH/sub 2/, and a highly-charged species containing both cobalt and chromium. The first-stage reaction occurs with a stoichiometry of 1:1 producing an intermediate with an absorption maximum at 460 nm for all starting reagents. The results were interpreted in terms of inner-sphere coordination of the cobaloxime to the Cr(II) and electron transfer through the oxime N-O bond.

  1. Coherence transfer and electron T1-, T2-relaxation in nitroxide spin labels

    DEFF Research Database (Denmark)

    Marsh, Derek

    2017-01-01

    -hyperfine anisotropies of isolated nitroxide spin labels. Results compatible with earlier treatments by Redfield theory are obtained without specifically evaluating matrix elements. Extension to single-transition operators for isolated nitroxides predicts electron coherence transfer by pseudosecular electron...

  2. In-silico assessment of protein-protein electron transfer. a case study: cytochrome c peroxidase--cytochrome c.

    Directory of Open Access Journals (Sweden)

    Frank H Wallrapp

    Full Text Available The fast development of software and hardware is notably helping in closing the gap between macroscopic and microscopic data. Using a novel theoretical strategy combining molecular dynamics simulations, conformational clustering, ab-initio quantum mechanics and electronic coupling calculations, we show how computational methodologies are mature enough to provide accurate atomistic details into the mechanism of electron transfer (ET processes in complex protein systems, known to be a significant challenge. We performed a quantitative study of the ET between Cytochrome c Peroxidase and its redox partner Cytochrome c. Our results confirm the ET mechanism as hole transfer (HT through residues Ala194, Ala193, Gly192 and Trp191 of CcP. Furthermore, our findings indicate the fine evolution of the enzyme to approach an elevated turnover rate of 5.47 × 10(6 s(-1 for the ET between Cytc and CcP through establishment of a localized bridge state in Trp191.

  3. A study of fast electron energy transport in relativistically intense laser-plasma interactions with large density scalelengths

    Energy Technology Data Exchange (ETDEWEB)

    Scott, R. H. H.; Norreys, P. A. [Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Perez, F.; Baton, S. D. [LULI, Ecole Polytechnique, UMR 7605, CNRS/CEA/UPMC, Route de Saclay, 91128 Palaiseau (France); Santos, J. J.; Nicolai, Ph.; Hulin, S. [Univ. Bordeaux/CNRS/CEA, CELIA, UMR 5107, 33405 Talence (France); Ridgers, C. P. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom); Davies, J. R. [GoLP, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Lancaster, K. L.; Trines, R. M. G. M. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Bell, A. R.; Tzoufras, M. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Rose, S. J. [Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom)

    2012-05-15

    A systematic experimental and computational investigation of the effects of three well characterized density scalelengths on fast electron energy transport in ultra-intense laser-solid interactions has been performed. Experimental evidence is presented which shows that, when the density scalelength is sufficiently large, the fast electron beam entering the solid-density plasma is best described by two distinct populations: those accelerated within the coronal plasma (the fast electron pre-beam) and those accelerated near or at the critical density surface (the fast electron main-beam). The former has considerably lower divergence and higher temperature than that of the main-beam with a half-angle of {approx}20 Degree-Sign . It contains up to 30% of the total fast electron energy absorbed into the target. The number, kinetic energy, and total energy of the fast electrons in the pre-beam are increased by an increase in density scalelength. With larger density scalelengths, the fast electrons heat a smaller cross sectional area of the target, causing the thinnest targets to reach significantly higher rear surface temperatures. Modelling indicates that the enhanced fast electron pre-beam associated with the large density scalelength interaction generates a magnetic field within the target of sufficient magnitude to partially collimate the subsequent, more divergent, fast electron main-beam.

  4. Direct electron transfer from glucose oxidase immobilized on a nano-porous glassy carbon electrode

    International Nuclear Information System (INIS)

    Haghighi, Behzad; Tabrizi, Mahmoud Amouzadeh

    2011-01-01

    Highlights: → A direct electron transfer reaction of glucose oxidase was observed on the surface of a nano-porous glassy carbon electrode. → A pair of well-defined and reversible redox peaks was observed at the formal potential of approximately -0.439 V. → The apparent electron transfer rate constant was measured to be 5.27 s -1 . → A mechanism for the observed direct electron transfer reaction was proposed, which consists of a two-electron and a two-proton transfer. - Abstract: A pair of well-defined and reversible redox peaks was observed for the direct electron transfer (DET) reaction of an immobilized glucose oxidase (GOx) on the surface of a nano-porous glassy carbon electrode at the formal potential (E o ') of -0.439 V versus Ag/AgCl/saturated KCl. The electron transfer rate constant (k s ) was calculated to be 5.27 s -1 . The dependence of E o ' on pH indicated that the direct electron transfer of the GOx was a two-electron transfer process, coupled with two-proton transfer. The results clearly demonstrate that the nano-porous glassy carbon electrode is a cost-effective and ready-to-use scaffold for the fabrication of a glucose biosensor.

  5. Direct electron transfer from glucose oxidase immobilized on a nano-porous glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Haghighi, Behzad, E-mail: haghighi@iasbs.ac.ir [Department of Chemistry, Institute for Advanced Studies in Basic Sciences, P.O. Box 45195-1159, Gava Zang, Zanjan (Iran, Islamic Republic of); Tabrizi, Mahmoud Amouzadeh [Department of Chemistry, Institute for Advanced Studies in Basic Sciences, P.O. Box 45195-1159, Gava Zang, Zanjan (Iran, Islamic Republic of)

    2011-11-30

    Highlights: > A direct electron transfer reaction of glucose oxidase was observed on the surface of a nano-porous glassy carbon electrode. > A pair of well-defined and reversible redox peaks was observed at the formal potential of approximately -0.439 V. > The apparent electron transfer rate constant was measured to be 5.27 s{sup -1}. > A mechanism for the observed direct electron transfer reaction was proposed, which consists of a two-electron and a two-proton transfer. - Abstract: A pair of well-defined and reversible redox peaks was observed for the direct electron transfer (DET) reaction of an immobilized glucose oxidase (GOx) on the surface of a nano-porous glassy carbon electrode at the formal potential (E{sup o}') of -0.439 V versus Ag/AgCl/saturated KCl. The electron transfer rate constant (k{sub s}) was calculated to be 5.27 s{sup -1}. The dependence of E{sup o}' on pH indicated that the direct electron transfer of the GOx was a two-electron transfer process, coupled with two-proton transfer. The results clearly demonstrate that the nano-porous glassy carbon electrode is a cost-effective and ready-to-use scaffold for the fabrication of a glucose biosensor.

  6. Channeling effect in electronic spectra produced by grazing impact of fast protons on insulator surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Archubi, C D; Gravielle, M S, E-mail: archubi@iafe.uba.a, E-mail: msilvia@iafe.uba.a [Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67, Sucursal 28, 1428, Buenos Aires (Argentina)

    2009-11-01

    Electron emission due to grazing scattering of fast protons from LiF and KCl surfaces is studied under axial incidence conditions. The differential emission probability is calculated within a distorted-wave formalism, taking into account axial channeled trajectories. For different emission angles, electronic spectra for proton incidence along the two principal crystal axes ([100] and [110]) are compared with those corresponding to an impact velocity in a random direction, finding effects associated with the channeling conditions.

  7. About the close collisions of the fast positrons and electrons with the string atoms

    International Nuclear Information System (INIS)

    Kudrin, V.V.; Vorobiev, S.A.

    1975-01-01

    The penetration behaviour of 20 MeV electron in MgO single crystal was studied. In the calculations the early described version of the binary collision model based on the classical mechanics was used. The classical theory has been shown to be valid for the scattering of the fast electrons in the crystal lattice. For the comparison with the behaviour of the positive particles the scattering of 20MeV positrons under the same conditions was simulated

  8. 77 FR 50243 - Electronic Fund Transfers (Regulation E)

    Science.gov (United States)

    2012-08-20

    ... transfers. DATES: This rule is effective February 7, 2013. FOR FURTHER INFORMATION CONTACT: Eric Goldberg... variation in the demand for remittance transfers, the Bureau believes that an annual figure is the most...

  9. Fast wave and electron cyclotron current drive in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Petty, C.C.; Pinsker, R.I.; Austin, M.E.

    1995-01-01

    The non-inductive current drive from directional fast Alfven and electron cyclotron waves was measured in the DIII-D tokamak in order to demonstrate these forms of radiofrequency (RF) current drive and to compare the measured efficiencies with theoretical expectations. The fast wave frequency was 8 times the deuterium cyclotron frequency at the plasma centre, while the electron cyclotron wave was at twice the electron cyclotron frequency. Complete non-inductive current drive was achieved using a combination of fast wave current drive (FWCD) and electron cyclotron current drive (ECCD) in discharges for which the total plasma current was inductively ramped down from 400 to 170 kA. For steady current discharges, an analysis of the loop voltage revealed up to 195 kA of a non-inductive current (out of 310 kA) during combined electron cyclotron and fast wave injection, with a maximum of 110 kA of FWCD and 80 kA of ECCD achieved (not simultaneously). The peakedness of the current profile increased with RF current drive, indicating that the driven current was centrally localized. The FWCD efficiency increased linearly with the central electron temperature as expected; however, the FWCD was severely degraded in low current discharges owing to incomplete fast wave absorption. The measured FWCD agreed with the predictions of a ray tracing code only when a parasitic loss of 4% per pass was included in the modelling along with multiple pass absorption. Enhancement of the second harmonic ECCD efficiency by the toroidal electric field was observed experimentally. The measured ECCD was in good agreement with Fokker-Planck code predictions. (author). 41 refs, 13 figs, 1 tab

  10. Electron transfer precedes ATP hydrolysis during nitrogenase catalysis

    Science.gov (United States)

    Duval, Simon; Danyal, Karamatullah; Shaw, Sudipta; Lytle, Anna K.; Dean, Dennis R.; Hoffman, Brian M.; Antony, Edwin; Seefeldt, Lance C.

    2013-01-01

    The biological reduction of N2 to NH3 catalyzed by Mo-dependent nitrogenase requires at least eight rounds of a complex cycle of events associated with ATP-driven electron transfer (ET) from the Fe protein to the catalytic MoFe protein, with each ET coupled to the hydrolysis of two ATP molecules. Although steps within this cycle have been studied for decades, the nature of the coupling between ATP hydrolysis and ET, in particular the order of ET and ATP hydrolysis, has been elusive. Here, we have measured first-order rate constants for each key step in the reaction sequence, including direct measurement of the ATP hydrolysis rate constant: kATP = 70 s−1, 25 °C. Comparison of the rate constants establishes that the reaction sequence involves four sequential steps: (i) conformationally gated ET (kET = 140 s−1, 25 °C), (ii) ATP hydrolysis (kATP = 70 s−1, 25 °C), (iii) Phosphate release (kPi = 16 s−1, 25 °C), and (iv) Fe protein dissociation from the MoFe protein (kdiss = 6 s−1, 25 °C). These findings allow completion of the thermodynamic cycle undergone by the Fe protein, showing that the energy of ATP binding and protein–protein association drive ET, with subsequent ATP hydrolysis and Pi release causing dissociation of the complex between the Feox(ADP)2 protein and the reduced MoFe protein. PMID:24062462

  11. Electron transfer precedes ATP hydrolysis during nitrogenase catalysis.

    Science.gov (United States)

    Duval, Simon; Danyal, Karamatullah; Shaw, Sudipta; Lytle, Anna K; Dean, Dennis R; Hoffman, Brian M; Antony, Edwin; Seefeldt, Lance C

    2013-10-08

    The biological reduction of N2 to NH3 catalyzed by Mo-dependent nitrogenase requires at least eight rounds of a complex cycle of events associated with ATP-driven electron transfer (ET) from the Fe protein to the catalytic MoFe protein, with each ET coupled to the hydrolysis of two ATP molecules. Although steps within this cycle have been studied for decades, the nature of the coupling between ATP hydrolysis and ET, in particular the order of ET and ATP hydrolysis, has been elusive. Here, we have measured first-order rate constants for each key step in the reaction sequence, including direct measurement of the ATP hydrolysis rate constant: kATP = 70 s(-1), 25 °C. Comparison of the rate constants establishes that the reaction sequence involves four sequential steps: (i) conformationally gated ET (kET = 140 s(-1), 25 °C), (ii) ATP hydrolysis (kATP = 70 s(-1), 25 °C), (iii) Phosphate release (kPi = 16 s(-1), 25 °C), and (iv) Fe protein dissociation from the MoFe protein (kdiss = 6 s(-1), 25 °C). These findings allow completion of the thermodynamic cycle undergone by the Fe protein, showing that the energy of ATP binding and protein-protein association drive ET, with subsequent ATP hydrolysis and Pi release causing dissociation of the complex between the Fe(ox)(ADP)2 protein and the reduced MoFe protein.

  12. Diameter dependent electron transfer kinetics in semiconductor-enzyme complexes.

    Science.gov (United States)

    Brown, Katherine A; Song, Qing; Mulder, David W; King, Paul W

    2014-10-28

    Excited state electron transfer (ET) is a fundamental step for the catalytic conversion of solar energy into chemical energy. To understand the properties controlling ET between photoexcited nanoparticles and catalysts, the ET kinetics were measured for solution-phase complexes of CdTe quantum dots and Clostridium acetobutylicum [FeFe]-hydrogenase I (CaI) using time-resolved photoluminescence spectroscopy. Over a 2.0-3.5 nm diameter range of CdTe nanoparticles, the observed ET rate (kET) was sensitive to CaI concentration. To account for diameter effects on CaI binding, a Langmuir isotherm and two geometric binding models were created to estimate maximal CaI affinities and coverages at saturating concentrations. Normalizing the ET kinetics to CaI surface coverage for each CdTe diameter led to k(ET) values that were insensitive to diameter, despite a decrease in the free energy for photoexcited ET (ΔGET) with increasing diameter. The turnover frequency (TOF) of CaI in CdTe-CaI complexes was measured at several molar ratios. Normalization for diameter-dependent changes in CaI coverage showed an increase in TOF with diameter. These results suggest that k(ET) and H2 production for CdTe-CaI complexes are not strictly controlled by ΔG(ET) and that other factors must be considered.

  13. Direct Electron Transfer of Dehydrogenases for Development of 3rd Generation Biosensors and Enzymatic Fuel Cells

    Directory of Open Access Journals (Sweden)

    Paolo Bollella

    2018-04-01

    Full Text Available Dehydrogenase based bioelectrocatalysis has been increasingly exploited in recent years in order to develop new bioelectrochemical devices, such as biosensors and biofuel cells, with improved performances. In some cases, dehydrogeases are able to directly exchange electrons with an appropriately designed electrode surface, without the need for an added redox mediator, allowing bioelectrocatalysis based on a direct electron transfer process. In this review we briefly describe the electron transfer mechanism of dehydrogenase enzymes and some of the characteristics required for bioelectrocatalysis reactions via a direct electron transfer mechanism. Special attention is given to cellobiose dehydrogenase and fructose dehydrogenase, which showed efficient direct electron transfer reactions. An overview of the most recent biosensors and biofuel cells based on the two dehydrogenases will be presented. The various strategies to prepare modified electrodes in order to improve the electron transfer properties of the device will be carefully investigated and all analytical parameters will be presented, discussed and compared.

  14. Electrochemical Measurement of Electron Transfer Kinetics by Shewanella oneidensis MR-1*

    Science.gov (United States)

    Baron, Daniel; LaBelle, Edward; Coursolle, Dan; Gralnick, Jeffrey A.; Bond, Daniel R.

    2009-01-01

    Shewanella oneidensis strain MR-1 can respire using carbon electrodes and metal oxyhydroxides as electron acceptors, requiring mechanisms for transferring electrons from the cell interior to surfaces located beyond the cell. Although purified outer membrane cytochromes will reduce both electrodes and metals, S. oneidensis also secretes flavins, which accelerate electron transfer to metals and electrodes. We developed techniques for detecting direct electron transfer by intact cells, using turnover and single turnover voltammetry. Metabolically active cells attached to graphite electrodes produced thin (submonolayer) films that demonstrated both catalytic and reversible electron transfer in the presence and absence of flavins. In the absence of soluble flavins, electron transfer occurred in a broad potential window centered at ∼0 V (versus standard hydrogen electrode), and was altered in single (ΔomcA, ΔmtrC) and double deletion (ΔomcA/ΔmtrC) mutants of outer membrane cytochromes. The addition of soluble flavins at physiological concentrations significantly accelerated electron transfer and allowed catalytic electron transfer to occur at lower applied potentials (−0.2 V). Scan rate analysis indicated that rate constants for direct electron transfer were slower than those reported for pure cytochromes (∼1 s−1). These observations indicated that anodic current in the higher (>0 V) window is due to activation of a direct transfer mechanism, whereas electron transfer at lower potentials is enabled by flavins. The electrochemical dissection of these activities in living cells into two systems with characteristic midpoint potentials and kinetic behaviors explains prior observations and demonstrates the complementary nature of S. oneidensis electron transfer strategies. PMID:19661057

  15. Cooperative electrocatalytic alcohol oxidation with electron-proton-transfer mediators

    Science.gov (United States)

    Badalyan, Artavazd; Stahl, Shannon S.

    2016-07-01

    electron-proton-transfer mediators, such as TEMPO, may be used in combination with first-row transition metals, such as copper, to achieve efficient two-electron electrochemical processes, thereby introducing a new concept for the development of non-precious-metal electrocatalysts.

  16. Three dimensional conjugated heat transfer analysis in sodium fast reactor wire-wrapped fuel assembly

    International Nuclear Information System (INIS)

    Peniguel, C.; Rupp, I.; Juhel, JP.; Rolfo, S.; Guillaud, M.; Gervais, N.

    2009-01-01

    Fast reactors with liquid metal coolant have recently received a renewed interest owing to a more efficient usage of the primary uranium resources, and they are one of the proposal for the next Generation IV. In order to evaluate nuclear power plant design and safety, 3D analysis of the flow and heat transfer in a wire spacer fuel assembly are ongoing at EDF. The introduction of the wire wrapped spacers, helically wound along the pin axis, enhances the mixing of the coolant between sub-channels and prevents contact between the fuel pins. The mesh generation step constitutes a challenging task if a reasonable amount of cells in conjunction with a suitable spatial discretization is wanted. Several approaches have been investigated and will be presented. Quite complex global flow patterns are found using either k-ε or preferably Reynolds Stress turbulent models. Preliminary conjugated heat transfer calculations using a coupling between the finite element thermal code SYRTHES and the finite volume CFD code Code Saturne are also shown. (author)

  17. Development of a Fast and Accurate PCRTM Radiative Transfer Model in the Solar Spectral Region

    Science.gov (United States)

    Liu, Xu; Yang, Qiguang; Li, Hui; Jin, Zhonghai; Wu, Wan; Kizer, Susan; Zhou, Daniel K.; Yang, Ping

    2016-01-01

    A fast and accurate principal component-based radiative transfer model in the solar spectral region (PCRTMSOLAR) has been developed. The algorithm is capable of simulating reflected solar spectra in both clear sky and cloudy atmospheric conditions. Multiple scattering of the solar beam by the multilayer clouds and aerosols are calculated using a discrete ordinate radiative transfer scheme. The PCRTM-SOLAR model can be trained to simulate top-of-atmosphere radiance or reflectance spectra with spectral resolution ranging from 1 cm(exp -1) resolution to a few nanometers. Broadband radiances or reflectance can also be calculated if desired. The current version of the PCRTM-SOLAR covers a spectral range from 300 to 2500 nm. The model is valid for solar zenith angles ranging from 0 to 80 deg, the instrument view zenith angles ranging from 0 to 70 deg, and the relative azimuthal angles ranging from 0 to 360 deg. Depending on the number of spectral channels, the speed of the current version of PCRTM-SOLAR is a few hundred to over one thousand times faster than the medium speed correlated-k option MODTRAN5. The absolute RMS error in channel radiance is smaller than 10(exp -3) mW/cm)exp 2)/sr/cm(exp -1) and the relative error is typically less than 0.2%.

  18. Fast electron flux driven by lower hybrid wave in the scrape-off layer

    International Nuclear Information System (INIS)

    Li, Y. L.; Xu, G. S.; Wang, H. Q.; Wan, B. N.; Chen, R.; Wang, L.; Gan, K. F.; Yang, J. H.; Zhang, X. J.; Liu, S. C.; Li, M. H.; Ding, S.; Yan, N.; Zhang, W.; Hu, G. H.; Liu, Y. L.; Shao, L. M.; Li, J.; Chen, L.; Zhao, N.

    2015-01-01

    The fast electron flux driven by Lower Hybrid Wave (LHW) in the scrape-off layer (SOL) in EAST is analyzed both theoretically and experimentally. The five bright belts flowing along the magnetic field lines in the SOL and hot spots at LHW guard limiters observed by charge coupled device and infrared cameras are attributed to the fast electron flux, which is directly measured by retarding field analyzers (RFA). The current carried by the fast electron flux, ranging from 400 to 6000 A/m 2 and in the direction opposite to the plasma current, is scanned along the radial direction from the limiter surface to the position about 25 mm beyond the limiter. The measured fast electron flux is attributed to the high parallel wave refractive index n || components of LHW. According to the antenna structure and the LHW power absorbed by plasma, a broad parallel electric field spectrum of incident wave from the antennas is estimated. The radial distribution of LHW-driven current density is analyzed in SOL based on Landau damping of the LHW. The analytical results support the RFA measurements, showing a certain level of consistency. In addition, the deposition profile of the LHW power density in SOL is also calculated utilizing this simple model. This study provides some fundamental insight into the heating and current drive effects induced by LHW in SOL, and should also help to interpret the observations and related numerical analyses of the behaviors of bright belts and hot spots induced by LHW

  19. The Iron-Sulfur Cluster of Electron Transfer Flavoprotein-ubiquinone Oxidoreductase (ETF-QO) is the Electron Acceptor for Electron Transfer Flavoprotein†

    Science.gov (United States)

    Swanson, Michael A.; Usselman, Robert J.; Frerman, Frank E.; Eaton, Gareth R.; Eaton, Sandra S.

    2011-01-01

    Electron-transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) accepts electrons from electron-transfer flavoprotein (ETF) and reduces ubiquinone from the ubiquinone-pool. It contains one [4Fe-4S]2+,1+ and one FAD, which are diamagnetic in the isolated oxidized enzyme and can be reduced to paramagnetic forms by enzymatic donors or dithionite. In the porcine protein, threonine 367 is hydrogen bonded to N1 and O2 of the flavin ring of the FAD. The analogous site in Rhodobacter sphaeroides ETF-QO is asparagine 338. Mutations N338T and N338A were introduced into the R. sphaeroides protein by site-directed mutagenesis to determine the impact of hydrogen bonding at this site on redox potentials and activity. The mutations did not alter the optical spectra, EPR g-values, spin-lattice relaxation rates, or the [4Fe-4S]2+,1+ to FAD point-dipole interspin distances. The mutations had no impact on the reduction potential for the iron-sulfur cluster, which was monitored by changes in the continuous wave EPR signals of the [4Fe-4S]+ at 15 K. For the FAD semiquinone, significantly different potentials were obtained by monitoring the titration at 100 or 293 K. Based on spectra at 293 K the N338T mutation shifted the first and second midpoint potentials for the FAD from +47 mV and −30 mV for wild type to −11 mV and −19 mV, respectively. The N338A mutation decreased the potentials to −37 mV and −49 mV. Lowering the midpoint potentials resulted in a decrease in the quinone reductase activity and negligible impact on disproportionation of ETF1e− catalyzed by ETF-QO. These observations indicate that the FAD is involved in electron transfer to ubiquinone, but not in electron transfer from ETF to ETF-QO. Therefore the iron-sulfur cluster is the immediate acceptor from ETF. PMID:18672901

  20. Electronic properties of Fe charge transfer complexes – A combined experimental and theoretical approach

    International Nuclear Information System (INIS)

    Ferreira, Hendrik; Eschwege, Karel G. von; Conradie, Jeanet

    2016-01-01

    Highlights: • Experimental and computational study of Fe II -phen, -bpy & -tpy compleesx. • Close correlations between experimental redox and spectral, and computational data. • Computational methods fast-track DSSC research. - Abstract: Dye-sensitized solar cell technology holds huge potential in renewable electricity generation of the future. Due to demand urgency, ways need to be explored to reduce research time and cost. Against this background, quantum computational chemistry is illustrated to be a reliable tool at the onset of studies in this field, simulating charge transfer, spectral (solar energy absorbed) and electrochemical (ease by which electrons may be liberated) tuning of related photo-responsive dyes. Comparative experimental and theoretical DFT studies were done under similar conditions, involving an extended series of electrochemically altered phenanthrolines, bipyridyl and terpyridyl complexes of Fe II . Fe II/III oxidation waves vary from 0.363 V for tris(3,6-dimethoxybipyridyl)Fe II to 0.894 V (versus Fc/Fc + ) for the 5-nitrophenanthroline complex. Theoretical DFT computed ionization potentials in the bipyridyl sub-series achieved an almost 100% linear correlation with experimental electrochemical oxidation potentials, while the phenanthroline sub-series gave R 2 = 0.95. Apart from the terpyridyl complex which accorded an almost perfect match, in general, TDDFT oscillators were computed at slightly lower energies than what was observed experimentally, while molecular HOMO and LUMO renderings reveal desired complexes with directional charge transfer propensities.

  1. Enhancement of the Number of Fast Electrons Generated in a Laser Inverse Cone Interaction

    International Nuclear Information System (INIS)

    Yan-Ling, Ji; Gang, Jiang; Wei-Dong, Wu; Ji-Cheng, Zhang; Yong-Jian, Tang

    2010-01-01

    Enhancement of the energy-conversion efficiency from laser to target electrons is demonstrated by two-dimensional particle-in-cell simulations in a laser-inverse cone interaction. When an intense short-pulse laser illuminates the inverse cone target, the electrons at the cone end are accelerated by the ponderomotive force. Then these electrons are guided and confined to transport along the inverse cone walls by the induced electromagnetic fields. A device consisting of inverse hollow-cone and multihole array plasma is proposed in order to increase the energy-conversion efficiency from laser to electrons. Particle-in-cell simulations present that the multiholes transpiercing the cone end help to enhance the number of fast electrons and the maximum electron energy significantly. (physics of gases, plasmas, and electric discharges)

  2. Direct interaction between linear electron transfer chains and solute transport systems in bacteria

    NARCIS (Netherlands)

    Elferink, Marieke G.L.; Hellingwerf, Klaas J.; Belkum, Marco J. van; Poolman, Bert; Konings, Wil N.

    1984-01-01

    In studies on alanine and lactose transport in Rhodopseudomonas sphaeroides we have demonstrated that the rate of solute uptake in this phototrophic bacterium is regulated by the rate of light-induced cyclic electron transfer. In the present paper the interaction between linear electron transfer

  3. Molecular dynamics simulation of the first electron transfer step in the oxygen reduction reaction

    NARCIS (Netherlands)

    Hartnig, C.B.; Koper, M.T.M.

    2002-01-01

    We present a molecular dynamics simulation of solvent reorganization in the first electron transfer step in the oxygen reduction reaction, i.e. O2+e-¿O2-, modeled as taking place in the outer Helmholtz plane. The first electron transfer step is usually considered the rate-determining step from many

  4. Photoinduced energy and electron transfer in rubrene-benzoquinone and rubrene-porphyrin systems

    KAUST Repository

    Khan, Jafar Iqbal

    2014-11-01

    Excited-state electron and energy transfer from singlet excited rubrene (Ru) to benzoquinone (BQ) and tetra-(4-aminophenyl) porphyrin (TAPP) were investigated by steady-state absorption and emission, time-resolved transient absorption, and femtosecond (fs)-nanosecond (ns) fluorescence spectroscopy. The low reduction potential of BQ provides the high probability of electron transfer from the excited Ru to BQ. Steady-state and time-resolved results confirm such an excited electron transfer scenario. On the other hand, strong spectral overlap between the emission of Ru and absorption of TAPP suggests that energy transfer is a possible deactivation pathway of the Ru excited state.

  5. Effect of resonant-to-bulk electron momentum transfer on the efficiency of electron-cyclotron current-drive

    International Nuclear Information System (INIS)

    Matsuda, Y.; Smith, G.R.; Cohen, R.H.

    1989-01-01

    Efficiency of current drive by electron cyclotron waves is investigated numerically by a bounce-averaged Fokker-Planck code to ellucidate the effects of momentum transfer from resonant to bulk-electrons, finite bulk temperature relative to the energy of resonant electrons, and trapped electrons. Comparisons are made with existing theories to assess their validity and quantitative difference between theory and code results. Difference of nearly a factor of 2 was found in efficiency between some theory and code results. (author)

  6. MHD [magnetohydrodynamic] modes driven by anomalous electron viscosity and their role in fast sawtooth crashes

    International Nuclear Information System (INIS)

    Aydemir, A.Y.

    1990-01-01

    We derive the dispersion relations for both small and large-Δ' modes (m ≥ 2, and m = 1 modes, respectively) driven by anomalous electron viscosity. Under the assumption that the anomalous kinematic electron viscosity is comparable to the anomalous electron thermal diffusivity, we find that the viscous mode typically has a higher growth rate than the corresponding resistive mode. We compare computational results in cylindrical and toroidal geometries with theory and present some nonlinear results for viscous m = 1 modes in both circular and D-shaped boundaries and discuss their possible rile in fast sawtooth crashes. 30 ref., 5 figs., 1 tab

  7. Generation of relativistic electron beam and its anomalous stopping in the fast ignition scheme

    International Nuclear Information System (INIS)

    Sengupta, S.; Sandhu, A.S.; Dharmadhikari, A.K.; Kumar, G.R.; Das, A.; Kaw, P.K.

    2005-01-01

    We present experimental/theoretical results concerning two main physics issues related to the fast ignition scheme viz. the nonlinear mechanism of conversion of incident laser energy into a relativistic electron beam at the critical layer and its subsequent transport through an overdense plasma. Theoretical/numerical modelling of the experimental data, firstly shows that the conversion of the laser energy into an inward propagating electron beam occurs through the nonlinear mechanism of wave breaking of plasma waves excited at the critical layer and, secondly the transport of the electron beam through the overdense plasma is influenced by electrostatically induced and/or turbulence induced anomalous resistivity. (author)

  8. Protein electron transfer: is biology (thermo)dynamic?

    International Nuclear Information System (INIS)

    Matyushov, Dmitry V

    2015-01-01

    Simple physical mechanisms are behind the flow of energy in all forms of life. Energy comes to living systems through electrons occupying high-energy states, either from food (respiratory chains) or from light (photosynthesis). This energy is transformed into the cross-membrane proton-motive force that eventually drives all biochemistry of the cell. Life’s ability to transfer electrons over large distances with nearly zero loss of free energy is puzzling and has not been accomplished in synthetic systems. The focus of this review is on how this energetic efficiency is realized. General physical mechanisms and interactions that allow proteins to fold into compact water-soluble structures are also responsible for a rugged landscape of energy states and a broad distribution of relaxation times. Specific to a protein as a fluctuating thermal bath is the protein-water interface, which is heterogeneous both dynamically and structurally. The spectrum of interfacial fluctuations is a consequence of protein’s elastic flexibility combined with a high density of surface charges polarizing water dipoles into surface nanodomains. Electrostatics is critical to the protein function and the relevant questions are: (i) What is the spectrum of interfacial electrostatic fluctuations? (ii) Does the interfacial biological water produce electrostatic signatures specific to proteins? (iii) How is protein-mediated chemistry affected by electrostatics? These questions connect the fluctuation spectrum to the dynamical control of chemical reactivity, i.e. the dependence of the activation free energy of the reaction on the dynamics of the bath. Ergodicity is often broken in protein-driven reactions and thermodynamic free energies become irrelevant. Continuous ergodicity breaking in a dense spectrum of relaxation times requires using dynamically restricted ensembles to calculate statistical averages. When applied to the calculation of the rates, this formalism leads to the nonergodic

  9. Laser pulse propagation and enhanced energy coupling to fast electrons in dense plasma gradients

    International Nuclear Information System (INIS)

    Gray, R J; Carroll, D C; Yuan, X H; Brenner, C M; Coury, M; Quinn, M N; Tresca, O; McKenna, P; Burza, M; Wahlström, C-G; Lancaster, K L; Neely, D; Lin, X X; Li, Y T

    2014-01-01

    Laser energy absorption to fast electrons during the interaction of an ultra-intense (10 20 W cm −2 ), picosecond laser pulse with a solid is investigated, experimentally and numerically, as a function of the plasma density scale length at the irradiated surface. It is shown that there is an optimum density gradient for efficient energy coupling to electrons and that this arises due to strong self-focusing and channeling driving energy absorption over an extended length in the preformed plasma. At longer density gradients the laser filaments, resulting in significantly lower overall energy coupling. As the scale length is further increased, a transition to a second laser energy absorption process is observed experimentally via multiple diagnostics. The results demonstrate that it is possible to significantly enhance laser energy absorption and coupling to fast electrons by dynamically controlling the plasma density gradient. (paper)

  10. A short comparison of electron and proton transfer processes in biological systems

    International Nuclear Information System (INIS)

    Bertrand, Patrick

    2005-01-01

    The main differences between electron and proton transfers that take place in biological systems are examined. The relation between the distance dependence of the rate constant and the mass of the transferred particle is analyzed in detail. Differences between the two processes have important consequences at the experimental level, which are discussed. The various mechanisms that ensure the coupling between electron and proton transfers are briefly described

  11. Demonstration of Lignin-to-Peroxidase Direct Electron Transfer

    Science.gov (United States)

    Sáez-Jiménez, Verónica; Baratto, Maria Camilla; Pogni, Rebecca; Rencoret, Jorge; Gutiérrez, Ana; Santos, José Ignacio; Martínez, Angel T.; Ruiz-Dueñas, Francisco Javier

    2015-01-01

    Versatile peroxidase (VP) is a high redox-potential peroxidase of biotechnological interest that is able to oxidize phenolic and non-phenolic aromatics, Mn2+, and different dyes. The ability of VP from Pleurotus eryngii to oxidize water-soluble lignins (softwood and hardwood lignosulfonates) is demonstrated here by a combination of directed mutagenesis and spectroscopic techniques, among others. In addition, direct electron transfer between the peroxidase and the lignin macromolecule was kinetically characterized using stopped-flow spectrophotometry. VP variants were used to show that this reaction strongly depends on the presence of a solvent-exposed tryptophan residue (Trp-164). Moreover, the tryptophanyl radical detected by EPR spectroscopy of H2O2-activated VP (being absent from the W164S variant) was identified as catalytically active because it was reduced during lignosulfonate oxidation, resulting in the appearance of a lignin radical. The decrease of lignin fluorescence (excitation at 355 nm/emission at 400 nm) during VP treatment under steady-state conditions was accompanied by a decrease of the lignin (aromatic nuclei and side chains) signals in one-dimensional and two-dimensional NMR spectra, confirming the ligninolytic capabilities of the enzyme. Simultaneously, size-exclusion chromatography showed an increase of the molecular mass of the modified residual lignin, especially for the (low molecular mass) hardwood lignosulfonate, revealing that the oxidation products tend to recondense during the VP treatment. Finally, mutagenesis of selected residues neighboring Trp-164 resulted in improved apparent second-order rate constants for lignosulfonate reactions, revealing that changes in its protein environment (modifying the net negative charge and/or substrate accessibility/binding) can modulate the reactivity of the catalytic tryptophan. PMID:26240145

  12. Tracing Fast Electron Beams Emanating from the Magnetic Reconnection Site in a Solar Jet

    Science.gov (United States)

    Chen, B.; Yu, S.; Battaglia, M.; Krucker, S.

    2017-12-01

    Fast electron beams propagating in the solar corona can emit radio waves commonly known as type III radio bursts. At decimetric wavelengths, these bursts are emitted from the low corona where flare energy release is thought to take place. As such, decimetric type III radio bursts can serve as an excellent tool to directly trace fast electron beams in the vicinity of the flare energy release site. Here we report observations of decimetric type III bursts during a jet event using the Jansky Very Large Array (VLA) in 1-2 GHz. Taking advantage of VLA's highly sensitive spectral imaging capability with an ultra-high cadence of 50 ms, we derive detailed trajectories of fast electron beams (with a bulk speed of at least 0.3-0.5c, or several tens of keV) and place them in the context of extreme ultraviolet and X-ray images obtained by SDO/AIA and RHESSI. Our results show that the electron beams originated in a region just below the jet and above the lower-lying small-scale flare loops, presumably where the magnetic energy release took place. We show that the electron beams appear in groups, each with a duration of only a few seconds. Each group, consisting of beams propagating along magnetic field lines at different angles, is seen to emanate from a single site trailing the jet, interpreted as the magnetic reconnection null point. Our results suggest, at least for the present case, that the fast electron beams were energized directly at the magnetic reconnection site which was highly inhomogeneous and fragmentary possibly down to kilometer scales.

  13. Pulse radiolytic and electrochemical investigations of intramolecular electron transfer in carotenoporphyrins and carotenoporphyrin-quinone triads

    International Nuclear Information System (INIS)

    Land, E.J.; Lexa, D.; Bensasson, R.V.; Gust, D.; Moore, T.A.; Moore, A.L.; Liddell, P.A.; Nemeth, G.A.

    1987-01-01

    Thermodynamic and kinetic aspects of intramolecular electron-transfer reactions in carotenoporphyrin dyads and carotenoid-porphyrin-quinone triads have been studied by using pulse radiolysis and cyclic voltammetry. Rapid (<1 μs) electron transfer from carotenoid radical anions to attached porphyrins has been inferred. Carotenoid cations, on the other hand, do not readily accept electrons from attached porphyrins or pyropheophorbides. Electrochemical studies provide the thermodynamic basis for these observations and also allow estimation of the energetics of photoinitiated two-step electron transfer and two-step charge recombination in triad models for photosynthetic charge separation

  14. FWCD (fast wave current drive) and ECCD (electron cyclotron current drive) experiments on DIII-D

    International Nuclear Information System (INIS)

    Prater, R.; Austin, M.; Baity, F.W.

    1994-01-01

    Fast wave current drive and electron cyclotron current drive experiments have been performed on the DIII-D tokamak as part of the advanced tokamak program. The goal of this program is to develop techniques for controlling the profile of the current density in order to access regimes of improved confinement and stability. The experiments on fast wave current drive used a four strap antenna with 90deg phasing between straps. A decoupler was used to help maintain the phasing, and feedback control of the plasma position was used to keep the resistive loading constant. RF pickup loops demonstrate that the directivity of the antenna is as expected. Plasma currents up to 0.18 MA were driven by 1.5 MW of fast wave power. Electron cyclotron current drive experiments at 60 GHz have shown 0.1 MA of plasma current driven by 1 MW of power. New fast wave and electron cyclotron heating systems are in development for DIII-D, so that the goals of the advanced tokamak program can be carried out. (author)

  15. Sausage instabilities in electron current channels and the problem of fast ignition

    International Nuclear Information System (INIS)

    Das, A.

    2002-01-01

    In the fast ignition concept of laser fusion, an intense picosecond laser pulse incident on an overdense pellet is absorbed by nonlinear mechanisms and gets converted into inward propagating fast electron currents. PIC simulations show that the return shielding currents due to cold plasma interact with the incoming currents and intense Weibel, tearing and coalescence instabilities take place, which organize the current into a few current channels. The stability of these current channels is thus a topic of great interest. We have carried out linear and nonlinear studies of 2 - dimensional sausage instabilities of a slab model of the current channels in the framework of electron magnetohydrodynamic fluid approximation. The analytic calculations and numerical simulations for some simple velocity profiles show the presence of linear instability driven by velocity shear. Nonlinear studies on the saturation of instabilities and their reaction back on the relaxation of the velocity profile have also been made. A discussion of the consequences of such EMHD turbulence induced relaxation and stopping of fast electrons, for the fast ignition concept will be presented. (author)

  16. FAST

    DEFF Research Database (Denmark)

    Zuidmeer-Jongejan, Laurian; Fernandez-Rivas, Montserrat; Poulsen, Lars K.

    2012-01-01

    ABSTRACT: The FAST project (Food Allergy Specific Immunotherapy) aims at the development of safe and effective treatment of food allergies, targeting prevalent, persistent and severe allergy to fish and peach. Classical allergen-specific immunotherapy (SIT), using subcutaneous injections with aqu...

  17. Influence of Plastic Deformation of Steel Samples on the Fast electron Backscattering

    International Nuclear Information System (INIS)

    Sierra Trujillo, J. X.; Herrera Palma, V.; Desdin Garcia, L. F.; Codorniu Pujals, D.

    2013-01-01

    A considerable fraction of a fast electron beam incident on a target is scattered in backward direction. It is a very complex process involving electron - nucleus and electron - electron collisions. The fraction of backscattered electrons is described by a parameterization as a function of the atomic number and energy of the incident electrons. In such approaches the possible influence of the material structure is not taken into account. In this paper, the behavior of the 90 Sr/ 90 Y backscattered electrons from 08JuA and 15GJuT steel strained samples is investigated. A clear dependence between the degree of plastic deformation and the fraction of backscattered electrons was observed. This relationship is explained by the interaction of electrons with the dislocations in the material, whose density depends on the magnitude of the strain in the plastic region. On the basis of a simple model for describing this interaction, a mathematical expression is obtained for the relationship between the fraction of backscattered electrons and the degree of deformation. (Author)

  18. Positronium Inhibition and Quenching by Organic Electron Acceptors and Charge Transfer Complexes

    DEFF Research Database (Denmark)

    Jansen, P.; Eldrup, Morten Mostgaard; Jensen, Bror Skytte

    1975-01-01

    Positron lifetime measurements were performed on a series of organic electron acceptors and charge-transfer complexes in solution. The acceptors cause both positronium (Ps) inhibition (with maybe one exception) and quenching, but when an acceptor takes part in a charge-transfer complex...... in terms of the spur reaction model of Ps formation. Correlation was also made to gas phase reaction between electron acceptors and free electron, as well as to pulse radiolysis data....

  19. 77 FR 6193 - Electronic Fund Transfers (Regulation E)

    Science.gov (United States)

    2012-02-07

    ...''); Manuel Orozco, Inter- American Dialogue, Migration and Remittances in Times of Recession: Effects on... Reserve Bank of India; study was not limited to transfers from the United States); see also Manuel Orozco..., transfers). \\10\\ Elizabeth M. Grieco, Patricia de la Cruz et al., Who in the United States Sends and...

  20. Long-range electron transfer in zinc-phthalocyanine-oligo(phenylene-ethynylene)-based donor-bridge-acceptor dyads.

    Science.gov (United States)

    Göransson, Erik; Boixel, Julien; Fortage, Jérôme; Jacquemin, Denis; Becker, Hans-Christian; Blart, Errol; Hammarström, Leif; Odobel, Fabrice

    2012-11-05

    In the context of long-range electron transfer for solar energy conversion, we present the synthesis, photophysical, and computational characterization of two new zinc(II) phthalocyanine oligophenylene-ethynylene based donor-bride-acceptor dyads: ZnPc-OPE-AuP(+) and ZnPc-OPE-C(60). A gold(III) porphyrin and a fullerene has been used as electron accepting moieties, and the results have been compared to a previously reported dyad with a tin(IV) dichloride porphyrin as the electron acceptor (Fortage et al. Chem. Commun. 2007, 4629). The results for ZnPc-OPE-AuP(+) indicate a remarkably strong electronic coupling over a distance of more than 3 nm. The electronic coupling is manifested in both the absorption spectrum and an ultrafast rate for photoinduced electron transfer (k(PET) = 1.0 × 10(12) s(-1)). The charge-shifted state in ZnPc-OPE-AuP(+) recombines with a relatively low rate (k(BET) = 1.0 × 10(9) s(-1)). In contrast, the rate for charge transfer in the other dyad, ZnPc-OPE-C(60), is relatively slow (k(PET) = 1.1 × 10(9) s(-1)), while the recombination is very fast (k(BET) ≈ 5 × 10(10) s(-1)). TD-DFT calculations support the hypothesis that the long-lived charge-shifted state of ZnPc-OPE-AuP(+) is due to relaxation of the reduced gold porphyrin from a porphyrin ring based reduction to a gold centered reduction. This is in contrast to the faster recombination in the tin(IV) porphyrin based system (k(BET) = 1.2 × 10(10) s(-1)), where the excess electron is instead delocalized over the porphyrin ring.

  1. Shielding computations for solution transfer lines from Analytical Lab to process cells of Demonstration Fast Reactor Plant (DFRP)

    International Nuclear Information System (INIS)

    Baskar, S.; Jose, M.T.; Baskaran, R.; Venkatraman, B.

    2018-01-01

    The diluted virgin solutions (both aqueous and organic) and aqueous analytical waste generated from experimental analysis of process solutions, pertaining to Fast Breeder Test Reactor (FBTR) and Prototype Fast Breeder Reactor (PFBR), in glove boxes of active analytical Laboratory (AAL) are pumped back to the process cells through a pipe in pipe arrangement. There are 6 transfer lines (Length 15-32 m), 2 for each type of transfer. The transfer lines passes through the area inside the AAL and also the operating area. Hence it is required to compute the necessary radial shielding requirement around the lines to limit the dose rates in both the areas to the permissible values as per the regulatory requirement

  2. Ultrafast Photoinduced Electron Transfer in Bimolecular Donor-Acceptor Systems

    KAUST Repository

    Alsulami, Qana

    2016-01-01

    , electronic properties and chemical structure. Interestingly, clear correlations among the steady-state measurements, time-resolved spectroscopy results, grain alignment of the electron transporting layer (ETL), carrier mobility, and device performance

  3. Modulation transfer function and detective quantum efficiency of electron bombarded charge coupled device detector for low energy electrons

    Czech Academy of Sciences Publication Activity Database

    Horáček, Miroslav

    2005-01-01

    Roč. 76, č. 9 (2005), 093704:1-6 ISSN 0034-6748 R&D Projects: GA ČR(CZ) GA202/03/1575 Keywords : electron bombarded CCD * modulation transfer function * detective quantum efficiency Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.235, year: 2005

  4. Enhanced Performance of Dye-Sensitized Solar Cells with Nanostructure Graphene Electron Transfer Layer

    Directory of Open Access Journals (Sweden)

    Chih-Hung Hsu

    2014-01-01

    Full Text Available The utilization of nanostructure graphene thin films as electron transfer layer in dye-sensitized solar cells (DSSCs was demonstrated. The effect of a nanostructure graphene thin film in DSSC structure was examined. The nanostructure graphene thin films provides a great electron transfer channel for the photogenerated electrons from TiO2 to indium tin oxide (ITO glass. Obvious improvements in short-circuit current density of the DSSCs were observed by using the graphene electron transport layer modified photoelectrode. The graphene electron transport layer reduces effectively the back reaction in the interface between the ITO transparent conductive film and the electrolyte in the DSSC.

  5. Development of an ISI robot for the fast breeder reactor MONJU primary heat transfer system piping

    International Nuclear Information System (INIS)

    Tagawa, Akihiro; Ueda, Masashi; Yamashita, Takuya; Narisawa, Masataka; Haga, Kouichi

    2011-01-01

    This paper describes the development of a new inspection robot for the In-Service Inspection of the heat transfer system of the Fast Breeder Reactor MONJU. The inspection was carried out using a tire-type ultrasonic sensor for volumetric tests at high temperature (atmosphere, 55degC; piping surface, 80degC) and radiation exposure condition (dose rate, 10 mGy/h; piping surface dose rate, 15 mGy/h). An inspection robot using a new tire type for the ultrasonic testing sensor and a new control method was developed. A signal-to-noise ratio S/N over 2 was obtained during the functional test for a calibration defect with a depth of 50%t (from the tube wall thickness). In the automatic inspection test, an EDM slit with a depth of 9% from the pipe thickness was detectable and with an S/N ratio = 4.0 (12.0 dB). (author)

  6. Development of a transfer model for design of sodium purification systems for Fast Breeder Reactors

    International Nuclear Information System (INIS)

    Khatcheressian, N.

    2013-01-01

    Operating a Sodium Fast Reactor (SFR) in reliable and safe conditions requires to master the quality of the sodium fluid coolant, regarding oxygen and hydrogen impurities contents. A cold trap is a purification unit in SFR, designed for maintaining oxygen and hydrogen contents within acceptable limits. The purification of these impurities is based on crystallization of sodium hydride on cold walls and sodium oxide or hydride on wire mesh packing. Indeed, as oxygen and hydrogen solubilities are nearly nil at temperatures close to the sodium fusion point, i.e. 97.8 C, on line sodium purification can be performed by crystallization of sodium oxide and hydride from liquid sodium flows. However, the management of cold trap performances is necessary to prevent from unforeseen maintenance operations, which could induce shut-down of the reactor. It is thus essential to understand how a cold trap fills up with impurities crystallization in order to optimize the design of this system and to overcome any problems during nominal operation. The objective is to develop a design and simulation tool for cold traps able to predict the location and the amount of the impurities deposited. Crystallization model involve phenomena coupling in a porous medium with hydrodynamics, heat and mass transfer, distinguishing nucleation and growth phases for each impurity. It enables to understand how thermo hydraulic conditions and growing impurities interact on each other. This analysis will adapt operating and management conditions in order to optimize purification requirements. (author) [fr

  7. Synergistic electron transfer effect-based signal amplification strategy for the ultrasensitive detection of dopamine.

    Science.gov (United States)

    Lu, Qiujun; Chen, Xiaogen; Liu, Dan; Wu, Cuiyan; Liu, Meiling; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo

    2018-05-15

    The selective and sensitive detection of dopamine (DA) is of great significance for the identification of schizophrenia, Huntington's disease, and Parkinson's disease from the perspective of molecular diagnostics. So far, most of DA fluorescence sensors are based on the electron transfer from the fluorescence nanomaterials to DA-quinone. However, the limited electron transfer ability of the DA-quinone affects the level of detection sensitivity of these sensors. In this work, based on the DA can reduce Ag + into AgNPs followed by oxidized to DA-quinone, we developed a novel silicon nanoparticles-based electron transfer fluorescent sensor for the detection of DA. As electron transfer acceptor, the AgNPs and DA-quinone can quench the fluorescence of silicon nanoparticles effectively through the synergistic electron transfer effect. Compared with traditional fluorescence DA sensors, the proposed synergistic electron transfer-based sensor improves the detection sensitivity to a great extent (at least 10-fold improvement). The proposed sensor shows a low detection limit of DA, which is as low as 0.1 nM under the optimal conditions. This sensor has potential applicability for the detection of DA in practical sample. This work has been demonstrated to contribute to a substantial improvement in the sensitivity of the sensors. It also gives new insight into design electron transfer-based sensors. Copyright © 2018. Published by Elsevier B.V.

  8. Long-range intramolecular electron transfer in aromatic radical anions and binuclear transition metal complexes

    DEFF Research Database (Denmark)

    Kuznetsov, A. M.; Ulstrup, Jens

    1981-01-01

    Intramolecular electron transfer (ET) over distances up to about 10 Å between states in which the electron is localized on donor and acceptor groups by interaction with molecular or external solvent nuclear motion occurs, in particular, in two classes of systems. The excess electron in anionic ra...

  9. The effect of intramolecular quantum modes on free energy relationships for electron transfer reactions

    DEFF Research Database (Denmark)

    Ulstrup, Jens; Jortner, Joshua

    1975-01-01

    A general quantum mechanical description of exothermic electron transfer reactions is formulated by treating such reactions as the nonradiative decay of a ''supermolecule'' consisting of the electron donor, the electron acceptor, and the polar solvent. In particular, the role of the high-frequenc...

  10. 48 CFR 52.232-33 - Payment by Electronic Funds Transfer-Central Contractor Registration.

    Science.gov (United States)

    2010-10-01

    ... Government under this contract shall be made by electronic funds transfer (EFT), except as provided in... 48 Federal Acquisition Regulations System 2 2010-10-01 2010-10-01 false Payment by Electronic... CONTRACT CLAUSES Text of Provisions and Clauses 52.232-33 Payment by Electronic Funds Transfer—Central...

  11. Electron Transfer in Donor-Bridge-Acceptor Systems and Derived Materials

    NARCIS (Netherlands)

    Oosterbaan, W.D.

    2002-01-01

    Some aspects of photoinduced electron transfer (ET) in (electron donor)-bridge-(electron acceptor) compounds (D-B-A) and derived materials are investigated. Aim I is to determine how and to which extent non-conjugated double bonds in an otherwise saturated hydrocarbon bridge affect the rate of

  12. Photoinduced electron transfer for an eosin-tyrosine conjugate. Activity of the tyrosinate anion in long-range electron transfer in a protein-like polymer matrix

    Energy Technology Data Exchange (ETDEWEB)

    Jones, G. II; Feng, Z.; Oh, C. [Boston Univ., MA (United States)

    1995-03-23

    The Xanthene dye eosin Y has been modified via a thiohydantoin link to the amine terminus of the amino acid L-tyrosine. Photochemical electron transfer involving the singlet state of the dye and the attached phenol-containing residue led to a reduction in eosin fluorescence quantum yield and lifetime for aqueous solutions at elevated pH. The conjugate provided an electron transfer product of relatively long lifetime (1 {mu}s range) observed by flash photolysis of solutions at pH 12.0, conditions under which the tyrosine moiety is ionized. The effects of binding of the conjugate in the polymer poly(vinylpyrrolidone) (PVP) on the rates of electron transfer of species of different charge type were examined. 30 refs., 5 figs., 1 tab.

  13. Cross sections of electron excitation out of metastable helium levels with a fast metastable target product produced via charge exchange

    International Nuclear Information System (INIS)

    Lagus, M.E.; Boffard, J.B.; Anderson, L.W.; Lin, C.C.

    1996-01-01

    Absolute direct cross sections for electron excitation out of the 2 3 S level and into the 3 3 D, 4 3 D, and 3 3 S levels of the helium atom from threshold to 500 eV and into the 3 3 P level over a more limited energy range have been measured using a fast metastable atomic beam target. We produce the metastable atoms via near-resonant charge exchange between a 1.6-keV He + ion beam and Cs vapor. Because this reaction is highly nonresonant with the ground state of helium, the charge-transfer process yields a primarily metastable beam. We use a thermal detector which we calibrate with ions to measure absolutely the neutral beam flux. The atomic beam is crossed by an electron beam, and we collect the resulting fluorescence at right angles to both the electron and atomic beams. We obtain the cross sections for excitation out of the 2 3 S level into the various excited levels by monitoring the emission out of the excited level of interest. copyright 1996 The American Physical Society

  14. Hot electron transport modelling in fast ignition relevant targets with non-Spitzer resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, D A; Hoarty, D J; Swatton, D J R [Plasma Physics Department, AWE, Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom); Hughes, S J, E-mail: david.chapman@awe.co.u [Computational Physics Group, AWE, Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom)

    2010-08-01

    The simple Lee-More model for electrical resistivity is implemented in the hybrid fast electron transport code THOR. The model is shown to reproduce experimental data across a wide range of temperatures using a small number of parameters. The effect of this model on the heating of simple Al targets by a short-pulse laser is studied and compared to the predictions of the classical Spitzer-Haerm resistivity. The model is then used in simulations of hot electron transport experiments using buried layer targets.

  15. Dipole and Coulomb forces in electron capture dissociation and electron transfer dissociation mass spectroscopy.

    Science.gov (United States)

    Świerszcz, Iwona; Skurski, Piotr; Simons, Jack

    2012-02-23

    Ab initio electronic structure calculations were performed on a doubly charged polypeptide model H(+)-Lys(Ala)(19)-CO-CH(NH(2))-CH(2)-SS-CH(2)-(NH(2))CH-CO-(Ala)(19)-Lys-H(+) consisting of a C-terminal protonated Lys followed by a 19-Ala α-helix with a 20th Ala-like unit whose side chain is linked by a disulfide bond to a corresponding Ala-like unit connected to a second 19-Ala α-helix terminated by a second C-terminal-protonated Lys. The Coulomb potentials arising from the two charged Lys residues and dipole potentials arising from the two oppositely directed 72 D dipoles of the α-helices act to stabilize the SS bond's σ* orbital. The Coulomb potentials provide stabilization of 1 eV, while the two large dipoles generate an additional 4 eV. Such stabilization allows the SS σ* orbital to attach an electron and thereby generate disulfide bond cleavage products. Although calculations are performed only on SS bond cleavage, discussion of N-C(α) bond cleavage caused by electron attachment to amide π* orbitals is also presented. The magnitudes of the stabilization energies as well as the fact that they arise from Coulomb and dipole potentials are supported by results on a small model system consisting of a H(3)C-SS-CH(3) molecule with positive and negative fractional point charges to its left and right designed to represent (i) two positive charges ca. 32 Å distant (i.e., the two charged Lys sites of the peptide model) and (ii) two 72 D dipoles (i.e., the two α-helices). Earlier workers suggested that internal dipole forces in polypeptides could act to guide incoming free electrons (i.e., in electron capture dissociation (ECD)) toward the positive end of the dipole and thus affect the branching ratios for cleaving various bonds. Those workers argued that, because of the huge mass difference between an anion donor and a free electron, internal dipole forces would have a far smaller influence over the trajectory of a donor (i.e., in electron transfer dissociation

  16. Experimental verification of the role of electron pressure in fast magnetic reconnection with a guide field

    International Nuclear Information System (INIS)

    Fox, W.; Sciortino, F.; Stechow, A. von; Jara-Almonte, J.

    2017-01-01

    We report detailed laboratory observations of the structure of a reconnection current sheet in a two-fluid plasma regime with a guide magnetic field. We observe and quantitatively analyze the quadrupolar electron pressure variation in the ion-diffusion region, as originally predicted by extended magnetohydrodynamics simulations. The projection of the electron pressure gradient parallel to the magnetic field contributes significantly to balancing the parallel electric field, and the resulting cross-field electron jets in the reconnection layer are diamagnetic in origin. Furthermore, these results demonstrate how parallel and perpendicular force balance are coupled in guide field reconnection and confirm basic theoretical models of the importance of electron pressure gradients for obtaining fast magnetic reconnection.

  17. Fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Y.; Wang, W. X.; LeBlanc, B. P.; Guttenfelder, W.; Kaye, S. M.; Ethier, S.; Mazzucato, E.; Bell, R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Lee, K. C. [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Domier, C. W. [University of California at Davis, Davis, California 95616 (United States); Smith, D. R. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Yuh, H. [Nova Photonics, Inc., Princeton, New Jersey 08540 (United States)

    2015-11-15

    In this letter, we report the first observation of the fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus eXperiment [Ono et al., Nucl. Fusion 40, 557 (2000)]. The observation was made in a set of RF-heated L-mode plasmas with toroidal magnetic field of 0.55 T and plasma current of 300 kA. It is observed that electron-scale turbulence spectral power (measured with a high-k collective microwave scattering system) decreases significantly following fast cessation of RF heating that occurs in less than 200 μs. The large drop in the turbulence spectral power has a short time delay of about 1–2 ms relative to the RF cessation and happens on a time scale of 0.5–1 ms, much smaller than the energy confinement time of about 10 ms. Power balance analysis shows a factor of about 2 decrease in electron thermal diffusivity after the sudden drop of turbulence spectral power. Measured small changes in equilibrium profiles across the RF cessation are unlikely able to explain this sudden reduction in the measured turbulence and decrease in electron thermal transport, supported by local linear stability analysis and both local and global nonlinear gyrokinetic simulations. The observations imply that nonlocal flux-driven mechanism may be important for the observed turbulence and electron thermal transport.

  18. Study of fast electron generation using multi beam of LFEX-class laser

    International Nuclear Information System (INIS)

    Hata, M; Nagatomo, H; Sakagami, H; Johzaki, T; Sentoku, Y

    2016-01-01

    Fast Ignition Realization Experiment project phase-I (FIREX-I) is being performed at Institute of Laser Engineering, Osaka University. In this project, the four-beam bundled high-energy Petawatt laser (LFEX) is being operated. LFEX laser provides great multi-beam irradiation flexibility, with the possibility of arrange the pulses in temporal sequence, spatially separate them in distinct spots of focus them in a single spot. In this paper, we study the two- beam interference effects on high-intensity picosecond laser-plasma interaction (LPI) by twodimensional relativistic Particle-In-Cell simulations. The interference causes surface perturbation, which enhances laser absorption and underdense plasma generation, increasing the accelerated electron number and their slope temperature. The laser-to-electron energy conversion efficiency for two-beam interference case is suitable for Fast Ignition (FI) compared to the single beam case, but the increment of fast electron divergence leads to lower energy coupling. To optimize the target design for FI, these interference effects should be taken into consideration. (paper)

  19. Electron correlations in single-electron capture from helium by fast protons and α particles

    International Nuclear Information System (INIS)

    Mancev, Ivan; Milojevic, Nenad

    2010-01-01

    Single-electron capture from heliumlike atomic systems by bare projectiles is investigated by means of the four-body boundary-corrected first Born approximation (CB1-4B). The effect of the dynamic electron correlation is explicitly taken into account through the complete perturbation potential. The quantum-mechanical post and prior transition amplitudes for single charge exchange encompassing symmetric and/or asymmetric collisions are derived in terms of two-dimensional real integrals in the case of the prior form and five-dimensional quadratures for the post form. An illustrative computation is performed for single-electron capture from helium by protons and α particles at intermediate and high impact energies. The role of dynamic correlations is examined as a function of increased projectile energy. The validity and utility of the proposed CB1-4B method is critically assessed in comparison with the existing experimental data for total cross sections, and excellent agreement is obtained.

  20. Study of the fast electron distribution function in lower hybrid and electron cyclotron current driven plasmas in the WT-3 tokamak

    International Nuclear Information System (INIS)

    Ogura, K.; Tanaka, H.; Ide, S.

    1991-01-01

    The distribution function f(p-vector) of fast electrons produced by lower hybrid current drive (LHCD) is investigated in the WT-3 tokamak, using a combination of measurements of the hard X-ray (HXR) angular distribution with respect to the toroidal magnetic field and observations of the HXR radial profile. The data obtained indicate the formation of a plateau-like region in f(p-vector) which corresponds to a region of resonant interaction between the lower hybrid (LH) wave and the electrons. The energy of the fast electrons in the peripheral plasma region is observed to be higher than that in the central plasma region under operational conditions with a high plasma current (I p ≥ 80 kA). At low current (I p < or approx. 50 kA), however, the energy of fast electrons is constant along the plasma radius. In the current ramp-up phase, fast electrons are generated in the directions normal to and opposite to the LH wave propagation. The latter case is ascribed to a negatively biased toroidal electric field induced by the current ramp-up. To study the characteristic change of f(p-vector) for various current drive mechanisms, HXR measurements are performed in electron cyclotron current driven (ECCD) plasma and in Ohmic heating (OH) plasma. In ECCD plasma, the perpendicular energy of fast electrons increases, which indicates that fast electrons are accelerated perpendicularly by electron cyclotron heating. In both LHCD and ECCD plasmas, fast electrons flow in the direction opposite to the wave propagation, while no such fast electrons are formed in OH plasma. (author). 33 refs, 16 figs, 1 tab

  1. Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Antipov, Sergey [Univ. of Chicago, IL (United States)

    2017-03-01

    Electron cloud instabilities affect the performance of many circular high-intensity particle accelerators. They usually have a fast growth rate and might lead to an increase of the transverse emittance and beam loss. A peculiar example of such an instability is observed in the Fermilab Recycler proton storage ring. Although this instability might pose a challenge for future intensity upgrades, its nature had not been completely understood. The phenomena has been studied experimentally by comparing the dynamics of stable and unstable beam, numerically by simulating the build-up of the electron cloud and its interaction with the beam, and analytically by constructing a model of an electron cloud driven instability with the electrons trapped in combined function dipoles. Stabilization of the beam by a clearing bunch reveals that the instability is caused by the electron cloud, trapped in beam optics magnets. Measurements of microwave propagation confirm the presence of the cloud in the combined function dipoles. Numerical simulations show that up to 10$^{-2}$ of the particles can be trapped by their magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a combined function dipole this multi-turn accumulation allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The estimated fast instability growth rate of about 30 revolutions and low mode frequency of 0.4 MHz are consistent with experimental observations and agree with the simulations. The created instability model allows investigating the beam stability for the future intensity upgrades.

  2. Theory of atom displacements induced by fast electron elastic scattering in solids

    International Nuclear Information System (INIS)

    Cruz, C. M.; Pinera, I.; Abreu, Y.; Leyva, A.

    2006-01-01

    Present contribution deals with the theoretical description of the conditions favoring the occurrence of single fast electron elastic scattering in solids, leading to the displacement of atoms from their crystalline sites. Firstly, the Moliere-Bethe-Goudsmit-Saunderson theory of Multiple Electron Scattering is applied, determining the limiting angle θ l over which the single electron elastic scattering prevails over the multiple one, leading to the evaluation of the total macroscopic cross-section for single electron elastic scattering on the basis of the Mott-Rutherford differential cross-section. On the basis of single electron elastic scattering by atoms in the solid matrix, it was determined the relative number of Atom Displacements produced by the Gamma Radiation as a primary act, as well as the energy and linear momentum of the ejected atoms. The statistical distributions of single electron elastic scattering and of those inducing Atom Displacements at different electron initial energies in comparison with the others electron inelastic scattering channels are discussed, where the statistical sampling methods on the basis of the rejection one where applied simulating different practical situations. (Full text)

  3. Role of coherence and delocalization in photo-induced electron transfer at organic interfaces

    Science.gov (United States)

    Abramavicius, V.; Pranculis, V.; Melianas, A.; Inganäs, O.; Gulbinas, V.; Abramavicius, D.

    2016-09-01

    Photo-induced charge transfer at molecular heterojunctions has gained particular interest due to the development of organic solar cells (OSC) based on blends of electron donating and accepting materials. While charge transfer between donor and acceptor molecules can be described by Marcus theory, additional carrier delocalization and coherent propagation might play the dominant role. Here, we describe ultrafast charge separation at the interface of a conjugated polymer and an aggregate of the fullerene derivative PCBM using the stochastic Schrödinger equation (SSE) and reveal the complex time evolution of electron transfer, mediated by electronic coherence and delocalization. By fitting the model to ultrafast charge separation experiments, we estimate the extent of electron delocalization and establish the transition from coherent electron propagation to incoherent hopping. Our results indicate that even a relatively weak coupling between PCBM molecules is sufficient to facilitate electron delocalization and efficient charge separation at organic interfaces.

  4. Effect of anode polarization on biofilm formation and electron transfer in Shewanella oneidensis/graphite felt microbial fuel cells.

    Science.gov (United States)

    Pinto, David; Coradin, Thibaud; Laberty-Robert, Christel

    2018-04-01

    In microbial fuel cells, electricity generation is assumed by bacterial degradation of low-grade organics generating electrons that are transferred to an electrode. The nature and efficiency of the electron transfer from the bacteria to the electrodes are determined by several chemical, physical and biological parameters. Specifically, the application of a specific potential at the bioanode has been shown to stimulate the formation of an electro-active biofilm, but the underlying mechanisms remain poorly understood. In this study, we have investigated the effect of an applied potential on the formation and electroactivity of biofilms established by Shewanella oneidensis bacteria on graphite felt electrodes in single- and double-chamber reactor configurations in oxic conditions. Using amperometry, cyclic voltammetry, and OCP/Power/Polarization curves techniques, we showed that a potential ranging between -0.3V and +0.5V (vs. Ag/AgCl/KCl sat.) and its converse application to a couple of electrodes leads to different electrochemical behaviors, anodic currents and biofilm architectures. For example, when the bacteria were confined in the anodic compartment of a double-chamber cell, a negative applied potential (-0.3V) at the bioanode favors a mediated electron transfer correlated with the progressive formation of a biofilm that fills the felt porosity and bridges the graphite fibers. In contrast, a positive applied potential (+0.3V) at the bioanode stimulates a direct electron transfer resulting in the fast-bacterial colonization of the fibers only. These results provide significant insight for the understanding of the complex bacteria-electrode interactions in microbial fuel cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Electron correlation in single-electron capture from helium by fast protons

    International Nuclear Information System (INIS)

    Purkait, M

    2012-01-01

    The differential and total cross sections for single charge exchange in p-He collisions have been calculated within the framework of four-body boundary corrected continuum intermediate state (BCCIS-4B) approximation. The effect of dynamic electron correlations is explicitly taken into account through the complete perturbation potentials.

  6. The Solid Waste Transfer Pit an FFTF [Fast Flux Test Facility] station for fuel and reflector transfer

    International Nuclear Information System (INIS)

    Milewski, A.J.; Thomson, J.D.

    1985-01-01

    This paper describes the design aspects of a proposed FFTF facility called the Solid Waste Transfer Pit (SWTP). This new facility will be used as a transfer station for reflectors and/or low decay heat fuel assemblies when movement from the Fuel Storage Facility for sodium removal and subsequent reprocessing is to be accomplished. The SWTP utilizes a shielded cell cover with an integral manually-operated gate valve for top loading of a transfer vessel. The cost-effective design discussed herein provides a practical approach using state-of-the-art concepts while assuring safe and reliable operation

  7. Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation

    Science.gov (United States)

    Delor, Milan; Archer, Stuart A.; Keane, Theo; Meijer, Anthony J. H. M.; Sazanovich, Igor V.; Greetham, Gregory M.; Towrie, Michael; Weinstein, Julia A.

    2017-11-01

    Ultrafast electron transfer in condensed-phase molecular systems is often strongly coupled to intramolecular vibrations that can promote, suppress and direct electronic processes. Recent experiments exploring this phenomenon proved that light-induced electron transfer can be strongly modulated by vibrational excitation, suggesting a new avenue for active control over molecular function. Here, we achieve the first example of such explicit vibrational control through judicious design of a Pt(II)-acetylide charge-transfer donor-bridge-acceptor-bridge-donor 'fork' system: asymmetric 13C isotopic labelling of one of the two -C≡C- bridges makes the two parallel and otherwise identical donor→acceptor electron-transfer pathways structurally distinct, enabling independent vibrational perturbation of either. Applying an ultrafast UVpump(excitation)-IRpump(perturbation)-IRprobe(monitoring) pulse sequence, we show that the pathway that is vibrationally perturbed during UV-induced electron transfer is dramatically slowed down compared to its unperturbed counterpart. One can thus choose the dominant electron transfer pathway. The findings deliver a new opportunity for precise perturbative control of electronic energy propagation in molecular devices.

  8. Electron Transfer in Flavodoxin-based Redox Maquettes

    NARCIS (Netherlands)

    Alagaratnam, S.

    2005-01-01

    Small redox proteins play the role of electron taxis in the cell, picking electrons up at one location and delivering them at another. While it is known that these reactions are the basis for the processes of energy generation by respiration and photosynthesis, the means by which these 'taxis'

  9. Application of Degenerately Doped Metal Oxides in the Study of Photoinduced Interfacial Electron Transfer.

    Science.gov (United States)

    Farnum, Byron H; Morseth, Zachary A; Brennaman, M Kyle; Papanikolas, John M; Meyer, Thomas J

    2015-06-18

    Degenerately doped In2O3:Sn semiconductor nanoparticles (nanoITO) have been used to study the photoinduced interfacial electron-transfer reactivity of surface-bound [Ru(II)(bpy)2(4,4'-(PO3H2)2-bpy)](2+) (RuP(2+)) molecules as a function of driving force over a range of 1.8 eV. The metallic properties of the ITO nanoparticles, present within an interconnected mesoporous film, allowed for the driving force to be tuned by controlling their Fermi level with an external bias while their optical transparency allowed for transient absorption spectroscopy to be used to monitor electron-transfer kinetics. Photoinduced electron transfer from excited-state -RuP(2+*) molecules to nanoITO was found to be dependent on applied bias and competitive with nonradiative energy transfer to nanoITO. Back electron transfer from nanoITO to oxidized -RuP(3+) was also dependent on the applied bias but without complication from inter- or intraparticle electron diffusion in the oxide nanoparticles. Analysis of the electron injection kinetics as a function of driving force using Marcus-Gerischer theory resulted in an experimental estimate of the reorganization energy for the excited-state -RuP(3+/2+*) redox couple of λ* = 0.83 eV and an electronic coupling matrix element, arising from electronic wave function overlap between the donor orbital in the molecule and the acceptor orbital(s) in the nanoITO electrode, of Hab = 20-45 cm(-1). Similar analysis of the back electron-transfer kinetics yielded λ = 0.56 eV for the ground-state -RuP(3+/2+) redox couple and Hab = 2-4 cm(-1). The use of these wide band gap, degenerately doped materials provides a unique experimental approach for investigating single-site electron transfer at the surface of oxide nanoparticles.

  10. Measurements of fast electron beams and soft X-ray emission from plasma-focus experiments

    Directory of Open Access Journals (Sweden)

    Surała Władysław

    2016-06-01

    Full Text Available The paper reports results of the recent experimental studies of pulsed electron beams and soft X-rays in plasma-focus (PF experiments carried out within a modified PF-360U facility at the NCBJ, Poland. Particular attention was focused on time-resolved measurements of the fast electron beams by means of two different magnetic analyzers, which could record electrons of energy ranging from about 41 keV to about 715 keV in several (6 or 8 measuring channels. For discharges performed with the pure deuterium filling, many strong electron signals were recorded in all the measuring channels. Those signals were well correlated with the first hard X-ray pulse detected by an external scintillation neutron-counter. In some of the analyzer channels, electron spikes (lasting about dozens of nanoseconds and appearing in different instants after the current peculiarity (so-called current dip were also recorded. For several discharges, fast ion beams, which were emitted along the z-axis and recorded with nuclear track detectors, were also investigated. Those measurements confirmed a multibeam character of the ion emission. The time-integrated soft X-ray images, which were taken side-on by means of a pinhole camera and sensitive X-ray films, showed the appearance of some filamentary structures and so-called hot spots. The application of small amounts of admixtures of different heavy noble gases, i.e. of argon (4.8% volumetric, krypton (1.6% volumetric, or xenon (0.8% volumetric, decreased intensity of the recorded electron beams, but increased intensity of the soft X-ray emission and showed more distinct and numerous hot spots. The recorded electron spikes have been explained as signals produced by quasi-mono-energetic microbeams emitted from tiny sources (probably plasma diodes, which can be formed near the observed hot spots.

  11. Bi-directional magnetic resonance based wireless power transfer for electronic devices

    International Nuclear Information System (INIS)

    Kar, Durga P.; Nayak, Praveen P.; Bhuyan, Satyanarayan; Mishra, Debasish

    2015-01-01

    In order to power or charge electronic devices wirelessly, a bi-directional wireless power transfer method has been proposed and experimentally investigated. In the proposed design, two receiving coils are used on both sides of a transmitting coil along its central axis to receive the power wirelessly from the generated magnetic fields through strongly coupled magnetic resonance. It has been observed experimentally that the maximum power transfer occurs at the operating resonant frequency for optimum electric load connected across the receiving coils on both side. The optimum wireless power transfer efficiency is 88% for the bi-directional power transfer technique compared 84% in the one side receiver system. By adopting the developed bi-directional power transfer method, two electronic devices can be powered up or charged simultaneously instead of a single device through usual one side receiver system without affecting the optimum power transfer efficiency

  12. Bi-directional magnetic resonance based wireless power transfer for electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Kar, Durga P.; Nayak, Praveen P.; Bhuyan, Satyanarayan; Mishra, Debasish [Department of Electronics and Instrumentation Engineering, Institute of Technical Education and Research, Siksha ‘O’ Anushandhan University, Bhubaneswar 751030 (India)

    2015-09-28

    In order to power or charge electronic devices wirelessly, a bi-directional wireless power transfer method has been proposed and experimentally investigated. In the proposed design, two receiving coils are used on both sides of a transmitting coil along its central axis to receive the power wirelessly from the generated magnetic fields through strongly coupled magnetic resonance. It has been observed experimentally that the maximum power transfer occurs at the operating resonant frequency for optimum electric load connected across the receiving coils on both side. The optimum wireless power transfer efficiency is 88% for the bi-directional power transfer technique compared 84% in the one side receiver system. By adopting the developed bi-directional power transfer method, two electronic devices can be powered up or charged simultaneously instead of a single device through usual one side receiver system without affecting the optimum power transfer efficiency.

  13. Electron transfer reactions of ruthenium(II) complexes with polyphenolic acids in micelles

    Energy Technology Data Exchange (ETDEWEB)

    Rajeswari, Angusamy [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India); Department of Chemistry, Fatima College, Madurai 625 018 (India); Ramdass, Arumugam [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India); Research Department of Chemistry, Aditanar College of Arts and Science, Tiruchendur 628 216 (India); Muthu Mareeswaran, Paulpandian [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India); Department of Industrial Chemistry, Alagappa University, Karaikudi 630 003 (India); Rajagopal, Seenivasan, E-mail: rajagopalseenivasan@yahoo.com [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India)

    2016-02-15

    The electron transfer in a microhetrogeneous system is a perfect mimic of biological electron transfer. The electron transfer between biologically important phenolic acids and ruthenium (II) complexes is systematically studied in the presence of anionic and cationic micelles. The photophysical properties of these ruthenium (II) complexes with anionic and cationic micelles and their binding abilities with these two type of micelles are also studies using absorption, emission and excited state lifetime spectral techniques. Pseudophase Ion Exchange (PIE) Model is applied to derive mechanism of electron transfer in two types of micelles. - Highlights: • Effect of microhetrogeneous system is studied using ruthenium (II) complexes and gallic acid is studied. • Pseudophase Ion exchange model is applied to derive the mechanism. • Binding constants are in the range of 10{sup 2}–10{sup 4} M{sup −1}.

  14. Synthesis of 3-Alkenyl-1-azaanthraquinones via Diels-Alder and Electron Transfer Reactions

    Directory of Open Access Journals (Sweden)

    Patrice Vanelle

    2002-12-01

    Full Text Available A convenient route to 3-alkenyl-1-azaanthraquinones via a hetero Diels-Alder reaction between an azadiene and naphthoquinone, a free radical chlorination and an electron transfer reaction is reported.

  15. 77 FR 71035 - Financial Management Service; Proposed Collection of Information: Electronic Funds Transfer (EFT...

    Science.gov (United States)

    2012-11-28

    ... DEPARTMENT OF THE TREASURY Fiscal Service Financial Management Service; Proposed Collection of Information: Electronic Funds Transfer (EFT) Market Research Study AGENCY: Financial Management Service, Fiscal Service, Treasury. ACTION: Notice and Request for comments. SUMMARY: The Financial Management...

  16. Ultrafast electron and energy transfer in dye-sensitized iron oxide and oxyhydroxide nanoparticles

    DEFF Research Database (Denmark)

    Gilbert, Benjamin; Katz, Jordan E.; Huse, Nils

    2013-01-01

    photo-initiated interfacial electron transfer. This approach enables time-resolved study of the fate and mobility of electrons within the solid phase. However, complete analysis of the ultrafast processes following dye photoexcitation of the sensitized iron(iii) oxide nanoparticles has not been reported....... We addressed this topic by performing femtosecond transient absorption (TA) measurements of aqueous suspensions of uncoated and DCF-sensitized iron oxide and oxyhydroxide nanoparticles, and an aqueous iron(iii)–dye complex. Following light absorption, excited state relaxation times of the dye of 115...... a four-state model of the dye-sensitized system, finding electron and energy transfer to occur on the same ultrafast timescale. The interfacial electron transfer rates for iron oxides are very close to those previously reported for DCF-sensitized titanium dioxide (for which dye–oxide energy transfer...

  17. Heterogeneous electron transfer kinetics and electrocatalytic behaviour of mixed self-assembled ferrocenes and SWCNT layers

    CSIR Research Space (South Africa)

    Nkosi, D

    2010-01-01

    Full Text Available The electron transfer dynamics and electrocatalytic behaviour of ferrocene-terminated self-assembled monolayers (SAMs), co-adsorbed with single-walled carbon nanotubes (SWCNTs) on a gold electrode, have been interrogated for the first time...

  18. Opto-electronic conversion logic behaviour through dynamic modulation of electron/energy transfer states at the TiO2-carbon quantum dot interface.

    Science.gov (United States)

    Wang, Fang; Zhang, Yonglai; Liu, Yang; Wang, Xuefeng; Shen, Mingrong; Lee, Shuit-Tong; Kang, Zhenhui

    2013-03-07

    Here we show a bias-mediated electron/energy transfer process at the CQDs-TiO(2) interface for the dynamic modulation of opto-electronic properties. Different energy and electron transfer states have been observed in the CQDs-TNTs system due to the up-conversion photoluminescence and the electron donation/acceptance properties of the CQDs decorated on TNTs.

  19. A comparison of mutagenic effects of common wheat by electron beam, fast neutron and 60Co gamma ray irradiation

    International Nuclear Information System (INIS)

    An Daochang; Wang Linqing

    1988-02-01

    After winter wheat was irradiated by electron beam, fast neutron and γ-rays, respectively, the RBE value of electron beam to both fast neutrons and γ-rays was less than one, the RBE value of fast neutron to γ-rays was largely more than one. This results indicated that biological effect of M 1 generation induced by electron beam was less than that of fast neutrons very much, and similar to γ-ray irradiation. With electron beam irradiation, the half-lethal doses of M 1 generation were from 185 to 370 Gy, closer to 370 Gy, the lethal doses from 740 to 925 Gy. M 2 mutation efficiency with electron beam treatment was larger as compared with that with both fast neutrons and γ-rays. A wider mutation spectrum and higher mutation efficiency compared with other physical mutagens can be obtained with electron beam irradiation, about 30% higher than that with γ-ray irradiation. The best doses of irradiation with electron beam were 370 to 555 Gy. Fast neutrons, a better dose of which was 25 Gy, could induce more mutants than that with γ-rays in M 2 generation. The dose in which biological injury reached to 50% was the best dose for M 2 mutants by electron beam irradiation

  20. Long-range intramolecular electron transfer in azurins

    DEFF Research Database (Denmark)

    Farver, O; Pecht, I

    1989-01-01

    . aeruginosa) and (6.0 +/- 1.0) x 10(8) M-1.s-1 (Alcaligenes); (ii) a slow unimolecular phase with specific rates of 44 +/- 7 s-1 in the former and 8.5 +/- 1.5 s-1 for the latter (all at 298 K, 0.1 M ionic strength). Concomitant with the fast reduction of Cu(II), the single disulfide bridge linking cysteine-3...

  1. Study of suprathermal electron transport in solid or compressed matter for the fast-ignitor scheme

    International Nuclear Information System (INIS)

    Perez, F.

    2010-01-01

    The inertial confinement fusion (ICF) concept is widely studied nowadays. It consists in quickly compressing and heating a small spherical capsule filled with fuel, using extremely energetic lasers. Since approximately 15 years, the fast-ignition (FI) technique has been proposed to facilitate the fuel heating by adding a particle beam - electrons generated by an ultra-intense laser - at the exact moment when the capsule compression is at its maximum. This thesis constitutes an experimental study of these electron beams generated by picosecond-scale lasers. We present new results on the characteristics of these electrons after they are accelerated by the laser (energy, divergence, etc.) as well as their interaction with the matter they pass through. The experimental results are explained and reveal different aspects of these laser-accelerated fast electrons. Their analysis allowed for significant progress in understanding several mechanisms: how they are injected into solid matter, how to measure their divergence, and how they can be automatically collimated inside compressed matter. (author) [fr

  2. Fast ions and hot electrons in the laser--plasma interaction

    International Nuclear Information System (INIS)

    Gitomer, S.J.; Jones, R.D.; Begay, F.; Ehler, A.W.; Kephart, J.F.; Kristal, R.

    1986-01-01

    Data on the emission of energetic ions produced in laser--matter interactions have been analyzed for a wide variety of laser wavelengths, energies, and pulse lengths. Strong correlation has been found between the bulk energy per AMU for fast ions measured by charge cups and the x-ray-determined hot electron temperature. Five theoretical models have been used to explain this correlation. The models include (1) a steady-state spherically symmetric fluid model with classical electron heat conduction, (2) a steady-state spherically symmetric fluid model with flux limited electron heat conduction, (3) a simple analytic model of an isothermal rarefaction followed by a free expansion, (4) the lasneX hydrodynamics code [Comments Plasma Phys. Controlled Fusion 2, 85 (1975)], calculations employing a spherical expansion and simple initial conditions, and (5) the lasneX code with its full array of absorption, transport, and emission physics. The results obtained with these models are in good agreement with the experiments and indicate that the detailed shape of the correlation curve between mean fast ion energy and hot electron temperature is due to target surface impurities at the higher temperatures (higher laser intensities) and to the expansion of bulk target material at the lower temperatures (lower laser intensities)

  3. Cherenkov-type diagnostics of fast electrons beams escaping from MCF facilities

    Energy Technology Data Exchange (ETDEWEB)

    Jakubowski, L.; Malinowski, K.; Mirowski, R.; Rabinski, M.; Sadowski, M.J.; Zebrowski, J. [Institute for Nuclear Studies - IPJ, 05-400 Otwock-Swierk (Poland)

    2011-07-01

    The paper presents the feasibility study, the measuring system and the first experimental results of a new method developed for direct detection of high-energy (super-thermal, ripple-born and runaway) electrons generated in magnetic confinement fusion (MCF) facilities. The technique in question is based on registration of the Cherenkov radiation, emitted by energetic electrons, moving through a transparent medium (radiator) with a velocity higher than the velocity of light in this material. The main aim of our studies was to develop a diagnostic technique applicable for measurements of fast electron beams within MCF devices. The IPJ team proposed Cherenkov-type probes because of their high spatial- and temporal-resolutions. The most important results of applications of the presented Cherenkov-type diagnostics have proved that the one- and four-channel versions of the detecting head are useful for studies of the fast (ripple-born and runaway) electrons in different MCF experiments. Experience collected during the described studies allows to introduce some changes in the radiator configuration and to modify the Cherenkov probe design. This document is composed of a paper followed by a poster

  4. Transferred metal electrode films for large-area electronic devices

    International Nuclear Information System (INIS)

    Yang, Jin-Guo; Kam, Fong-Yu; Chua, Lay-Lay

    2014-01-01

    The evaporation of metal-film gate electrodes for top-gate organic field-effect transistors (OFETs) limits the minimum thickness of the polymer gate dielectric to typically more than 300 nm due to deep hot metal atom penetration and damage of the dielectric. We show here that the self-release layer transfer method recently developed for high-quality graphene transfer is also capable of giving high-quality metal thin-film transfers to produce high-performance capacitors and OFETs with superior dielectric breakdown strength even for ultrathin polymer dielectric films. Dielectric breakdown strengths up to 5–6 MV cm −1 have been obtained for 50-nm thin films of polystyrene and a cyclic olefin copolymer TOPAS ® (Zeon). High-quality OFETs with sub-10 V operational voltages have been obtained this way using conventional polymer dielectrics and a high-mobility polymer semiconductor poly[2,5-bis(3-tetradecylthiophene-2-yl)thieno[3,2-b]thiophene-2,5-diyl]. The transferred metal films can make reliable contacts without damaging ultrathin polymer films, self-assembled monolayers and graphene, which is not otherwise possible from evaporated or sputtered metal films

  5. Electron transfer and atom exchange between aqueous Fe(II) and structural Fe(III) in clays. Role in U and Hg(II) transformations

    Energy Technology Data Exchange (ETDEWEB)

    Scherer, Michelle [Univ. of Iowa, Iowa City, IA (United States)

    2016-08-31

    During this project, we investigated Fe electron transfer and atom exchange between aqueous Fe(II) and structural Fe(III) in clay minerals. We used selective chemical extractions, enriched Fe isotope tracer experiments, computational molecular modeling, and Mössbauer spectroscopy. Our findings indicate that structural Fe(III) in clay minerals is reduced by aqueous Fe(II) and that electron transfer occurs when Fe(II) is sorbed to either basal planes and edge OH-groups of clay mineral. Findings from highly enriched isotope experiments suggest that up to 30 % of the Fe atoms in the structure of some clay minerals exhanges with aqueous Fe(II). First principles calculations using a small polaron hopping approach suggest surprisingly fast electron mobility at room temperature in a nontronite clay mineral and are consistent with temperature dependent Mössbauer data Fast electron mobility suggests that electrons may be able to conduct through the mineral fast enough to enable exchange of Fe between the aqueous phase and clay mineral structure. over the time periods we observed. Our findings suggest that Fe in clay minerals is not as stable as previously thought.

  6. Charge transfer in quasi-one-electron systems at 'high' energy

    Energy Technology Data Exchange (ETDEWEB)

    Gay, T.J.; Redd, E.; Blankenship, D.M.; Park, J.T.; Peacher, J.L.; Seeley, D.G.

    1988-08-14

    We have made absolute and relative measurements of differential cross sections for single-electron transfer in collisions between Mg/sup +/ (30-150 keV) and Be/sup +/ (56.25 keV) ions and He atoms. The behaviour of transfer probability as a function of impact parameter can be understood qualitatively from recent molecular orbital calculations of quasi-one-electron systems.

  7. Electron transfer reactions in structural units of copper proteins

    International Nuclear Information System (INIS)

    Faraggi, M.

    1975-01-01

    In previous pulse radiolysis studies it was suggested that the reduction of the Cu(II) ions in copper proteins by the hydrated electron is a multi-step electron migration process. The technique has been extended to investigate the reduction of some structural units of these proteins. These studies include: the reaction of the hydrated electron with peptides, the reaction of the disulphide bridge with formate radical ion and radicals produced by the reduction of peptides, and the reaction of Cu(II)-peptide complex with esub(aq)sup(-) and CO 2 - . Using these results the reduction mechanism of copper and other proteins will be discussed. (author)

  8. New Oxime Ligand with Potential for Proton-Coupled Electron-Transfer Reactions

    DEFF Research Database (Denmark)

    Deville, Claire; Sundberg, Jonas; McKenzie, Christine Joy

    Proton-coupled electron-transfer (PCET) is found in a range of oxidation-reduction reactions in biology.1 This mechanism is of interest for applications in energy conversion processes. The PCET reaction has been shown to be facilitated when the proton is transferred to an intramolecular basic sit...

  9. One-electron redox potentials and rate of electron transfer in aqueous micellar solution. Partially solubilized quinones

    International Nuclear Information System (INIS)

    Almgren, M.; Grieser, F.; Thomas, J.K.

    1979-01-01

    The electron transfer equilibrium between AQS/AQS - and DQ/DQ - (where AQS is sodium 9,10-arthraquinone-2-sulfonate and DQ, duroquinone) has been studied by pulse radiolysis in aqueous micellar solutions of sodium lauryl sulfate. The equilibrium constant is changed as would be expected if AQS, AQS - , and DQ- were all mainly in the aqueous solution, and DQ distributed between the micelles and the aqueous phase with a distribution constant of K/sub D//N = 150 M -1 , in agreement with the independently determined value of this constant. The kinetics of the equilibration show, however, that electron transfer at the micelle surface is important, indicating that also AQS and DQ - are associated with the micelle to some extent. With reasonable assumptions regarding the distribution constants of these species (that have some independent support), the observed catalytic effect of the micelles on the electron transfer from DQ - to AQS can be understood

  10. Energy transfer dynamics in trimers and aggregates of light-harvesting complex II probed by 2D electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Enriquez, Miriam M.; Zhang, Cheng; Tan, Howe-Siang, E-mail: howesiang@ntu.edu.sg [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Akhtar, Parveen; Garab, Győző; Lambrev, Petar H., E-mail: lambrev@brc.hu [Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged (Hungary)

    2015-06-07

    The pathways and dynamics of excitation energy transfer between the chlorophyll (Chl) domains in solubilized trimeric and aggregated light-harvesting complex II (LHCII) are examined using two-dimensional electronic spectroscopy (2DES). The LHCII trimers and aggregates exhibit the unquenched and quenched excitonic states of Chl a, respectively. 2DES allows direct correlation of excitation and emission energies of coupled states over population time delays, hence enabling mapping of the energy flow between Chls. By the excitation of the entire Chl b Q{sub y} band, energy transfer from Chl b to Chl a states is monitored in the LHCII trimers and aggregates. Global analysis of the two-dimensional (2D) spectra reveals that energy transfer from Chl b to Chl a occurs on fast and slow time scales of 240–270 fs and 2.8 ps for both forms of LHCII. 2D decay-associated spectra resulting from the global analysis identify the correlation between Chl states involved in the energy transfer and decay at a given lifetime. The contribution of singlet–singlet annihilation on the kinetics of Chl energy transfer and decay is also modelled and discussed. The results show a marked change in the energy transfer kinetics in the time range of a few picoseconds. Owing to slow energy equilibration processes, long-lived intermediate Chl a states are present in solubilized trimers, while in aggregates, the population decay of these excited states is significantly accelerated, suggesting that, overall, the energy transfer within the LHCII complexes is faster in the aggregated state.

  11. Multislice theory of fast electron scattering incorporating atomic inner-shell ionization

    International Nuclear Information System (INIS)

    Dwyer, C.

    2005-01-01

    It is demonstrated how atomic inner-shell ionization can be incorporated into a multislice theory of fast electron scattering. The resulting theory therefore accounts for both inelastic scattering due to inner-shell ionization and dynamical elastic scattering. The theory uses a description of the ionization process based on the angular momentum representation for both the initial and final states of the atomic electron. For energy losses near threshold, only a small number of independent states of the ejected atomic electron need to be considered, reducing demands on computing time, and eliminating the need for tabulated inelastic scattering factors. The theory is used to investigate the influence of the collection aperture size on the spatial origin of the silicon K-shell EELS signal generated by a STEM probe. The validity of a so-called local approximation is also considered

  12. Interplanetary scattering of fast solar electrons deduced from type III bursts observed at low frequencies

    International Nuclear Information System (INIS)

    Alvarez, H.; Lin, R.P.

    1976-01-01

    Observations of low frequency solar type III radio bursts and the associated fast solar electrons show that the total path length travelled by the particles between the Sun and the Earth is significantly greater than the length of the smooth Archimedean spiral trajectory followed by the centroid of the type III exciter (Alvarez et al., 1975). Here it is assumed that the ratio of electron path length and the spiral length increases approximately as rsup(n), where r is heliocentric distance, and then compute the radio bursts arrival time at 1 AU for different values of n. A comparison with the radio observations indicates that the best fit occurs for n=1.5+-1.0. These results are interpreted in terms of the variation of electron scattering with heliocentric distance. (Auth.)

  13. Double electron transfer in ion-atom collisions

    International Nuclear Information System (INIS)

    Martinez, A.E

    1990-01-01

    Continuum distorted wave (CDW) and CDW-EIS (electron-ion scattering) approximations are used to study the resonant double capture by collision of alpha particles on He targets for intermediate and high energies. Calculations of total cross-sections based on the Independent Event Approximation are presented. A good agreement with experimental results was found, even without the inclusion of the dynamic and angular correlation of captured electrons. (Author). 11 refs., 1 fig

  14. Molecular Computational Investigation of Electron Transfer Kinetics across Cytochrome-Iron Oxide Interfaces

    International Nuclear Information System (INIS)

    Kerisit, Sebastien N.; Rosso, Kevin M.; Dupuis, Michel; Valiev, Marat

    2007-01-01

    The interface between electron transfer proteins such as cytochromes and solid phase mineral oxides is central to the activity of dissimilatory-metal reducing bacteria. A combination of potential-based molecular dynamics simulations and ab initio electronic structure calculations are used in the framework of Marcus' electron transfer theory to compute elementary electron transfer rates from a well-defined cytochrome model, namely the small tetraheme cytochrome (STC) from Shewanella oneidensis, to surfaces of the iron oxide mineral hematite (a-Fe2O3). Room temperature molecular dynamics simulations show that an isolated STC molecule favors surface attachment via direct contact of hemes I and IV at the poles of the elongated axis, with electron transfer distances as small as 9 Angstroms. The cytochrome remains attached to the mineral surface in the presence of water and shows limited surface diffusion at the interface. Ab initio electronic coupling matrix element (VAB) calculations of configurations excised from the molecular dynamics simulations reveal VAB values ranging from 1 to 20 cm-1, consistent with nonadiabaticity. Using these results, together with experimental data on the redox potential of hematite and hemes in relevant cytochromes and calculations of the reorganization energy from cluster models, we estimate the rate of electron transfer across this model interface to range from 1 to 1000 s-1 for the most exothermic driving force considered in this work, and from 0.01 to 20 s-1 for the most endothermic. This fairly large range of electron transfer rates highlights the sensitivity of the rate upon the electronic coupling matrix element, which is in turn dependent on the fluctuations of the heme configuration at the interface. We characterize this dependence using an idealized bis-imidazole heme to compute from first principles the VAB variation due to porphyrin ring orientation, electron transfer distance, and mineral surface termination. The electronic

  15. Effect of resonant-to-bulk electron momentum transfer on the efficiency of electron-cyclotron current drive

    International Nuclear Information System (INIS)

    Matsuda, Y.; Smith, G.R.; Cohen, R.H.

    1988-01-01

    Efficiency of current drive by electron-cyclotron waves is investigated numerically by a bounce-average Fokker-Planck code to elucidate the effects of momentum transfer from resonant to bulk electrons, finite bulk temperature relative to the energy of resonant electrons, and trapped electrons. Comparisons are made with existing theories to assess their validity and quantitative difference between theory and code results. Difference of nearly a factor of 2 was found in efficiency between some theory and code results. 4 refs., 4 figs

  16. Fast front-end L0 trigger electronics for ALICE FMD-MCP tests and performance

    CERN Document Server

    Efimov, L G; Kasatkan, V; Klempt, W; Kuts, V; Lenti, V; Platanov, V; Rudge, A; Stolyarov, O I; Tsimbal, F A; Valiev, F F; Villalobos Baillie, O; Vinogradov, L I; Zhigunov, O

    1997-01-01

    We present design details and new measurements of the performance of fast electronics for the Forward Multiplicity Detector for ALICE. These detectors based on sector type Microchannel Plates (MCP) forming several disks gave the very first trigger decision in the experiment (L0). Fast passive summators integrated with the detectors are used for linear summation of up to eight isochronous signal channels from MCP pads belonging to one sector. Two types of microelectronics design thin film summators were produced. We present test results for these summators, working in the frequency range up to 1 Ghz. New low noise preamplifiers have been built to work with these summators. The new design shows a good performance with the usable frequency range extended up to 1 Ghz. An upgrade of the functional scheme for the L0 ALICE pre-trigger design is also presented.Abstract:List of figures Figure 1: ALICE L0 Trigger Front-End Electronics Functional Scheme. Figure 2: UHF design for a fast passive summator based on direct...

  17. The dipole moment of the electron carrier adrenodoxin is not critical for redox partner interaction and electron transfer.

    Science.gov (United States)

    Hannemann, Frank; Guyot, Arnaud; Zöllner, Andy; Müller, Jürgen J; Heinemann, Udo; Bernhardt, Rita

    2009-07-01

    Dipole moments of proteins arise from helical dipoles, hydrogen bond networks and charged groups at the protein surface. High protein dipole moments were suggested to contribute to the electrostatic steering between redox partners in electron transport chains of respiration, photosynthesis and steroid biosynthesis, although so far experimental evidence for this hypothesis was missing. In order to probe this assumption, we changed the dipole moment of the electron transfer protein adrenodoxin and investigated the influence of this on protein-protein interactions and electron transfer. In bovine adrenodoxin, the [2Fe-2S] ferredoxin of the adrenal glands, a dipole moment of 803 Debye was calculated for a full-length adrenodoxin model based on the Adx(4-108) and the wild type adrenodoxin crystal structures. Large distances and asymmetric distribution of the charged residues in the molecule mainly determine the observed high value. In order to analyse the influence of the resulting inhomogeneous electric field on the biological function of this electron carrier the molecular dipole moment was systematically changed. Five recombinant adrenodoxin mutants with successively reduced dipole moment (from 600 to 200 Debye) were analysed for their redox properties, their binding affinities to the redox partner proteins and for their function during electron transfer-dependent steroid hydroxylation. None of the mutants, not even the quadruple mutant K6E/K22Q/K24Q/K98E with a dipole moment reduced by about 70% showed significant changes in the protein function as compared with the unmodified adrenodoxin demonstrating that neither the formation of the transient complex nor the biological activity of the electron transfer chain of the endocrine glands was affected. This is the first experimental evidence that the high dipole moment observed in electron transfer proteins is not involved in electrostatic steering among the proteins in the redox chain.

  18. Observations of fast magnetospheric echoes of artificially injected electrons above an auroral arc

    International Nuclear Information System (INIS)

    Wilhelm, K.; Becker, C.; Schmidt, R.

    1984-04-01

    Electron beam experiments using rocket-borne instrumentation have confirmed earlier observations of fast magnetospheric echoes of artificially injected energetic electrons. These experiments were jointly carried out by the University of Minnesota, the National Research Council of Canada and the Max-Planck-Institut fuer Aeronomie. A total of 234 echoes have been observed in a pitch angle range from 0 0 to 110 0 at energies of 1.87 and 3.90 keV. Out of this number, 95 echoes could unambiguously be identified with known accelerator operations at 2, 4 or 8 keV energy and highest current levels resulting in the determination of transit times of typically 400 ms. In most cases, when echoes were present in both energy channels, the higher energy electrons led the lower energy ones by approximately 50 ms. No echoes have been found in the 7.9 keV-detector channels. Adiabatic theory applied to these observations yields a reflection height of 3000 to 4000 km. The injection process is briefly discussed as the strong beam-plasma interaction that occurred near the electron accelerator appears to be instrumental in generating the source of heated electrons required for successful echo detection. Two consequences of this interaction, namely, strong energy and pitch angle diffusion and electron acceleration are illustrated with several examples. (orig.) [de

  19. Effect of donor orientation on ultrafast intermolecular electron transfer in coumarin-amine systems

    International Nuclear Information System (INIS)

    Singh, P. K.; Nath, S.; Bhasikuttan, A. C.; Kumbhakar, M.; Mohanty, J.; Sarkar, S. K.; Mukherjee, T.; Pal, H.

    2008-01-01

    Effect of donor amine orientation on nondiffusive ultrafast intermolecular electron transfer (ET) reactions in coumarin-amine systems has been investigated using femtosecond fluorescence upconversion measurements. Intermolecular ET from different aromatic and aliphatic amines used as donor solvents to the excited coumarin-151 (C151) acceptor occurs with ultrafast rates such that the shortest fluorescence lifetime component (τ 1 ) is the measure of the fastest ET rate (τ 1 =τ ET fast =(k ET fast ) -1 ), assigned to the C151-amine contact pairs in which amine donors are properly oriented with respect to C151 to maximize the acceptor-donor electronic coupling (V el ). It is interestingly observed that as the amine solvents are diluted by suitable diluents (either keeping solvent dielectric constant similar or with increasing dielectric constant), the τ 1 remains almost in the similar range as long as the amine dilution does not cross a certain critical limit, which in terms of the amine mole fraction (x A ) is found to be ∼0.4 for aromatic amines and ∼0.8 for aliphatic amines. Beyond these dilutions in the two respective cases of the amine systems, the τ 1 values are seen to increase very sharply. The large difference in the critical x A values involving aromatic and aliphatic amine donors has been rationalized in terms of the largely different orientational restrictions for the ET reactions as imposed by the aliphatic (n-type) and aromatic (π-type) nature of the amine donors [A. K. Satpati et al., J. Mol. Struct. 878, 84 (2008)]. Since the highest occupied molecular orbital (HOMO) of the n-type aliphatic amines is mostly centralized at the amino nitrogen, only some specific orientations of these amines with respect to the close-contact acceptor dye [also of π-character; A. K. Satpati et al., J. Mol. Struct. 878, 84 (2008) and E. W. Castner et al., J. Phys. Chem. A 104, 2869 (2000)] can give suitable V el and thus ultrafast ET reaction. In contrary, the

  20. Dynamics of transfer of electron excitation in a donor-acceptor system with a carbon chain and ways of its relaxation

    Directory of Open Access Journals (Sweden)

    M.M. Sevryukova

    2017-12-01

    Full Text Available The optical properties and dynamics of transport of electron excitation and the ways of its relaxation in the supramolecular D–π–A complex on the basis of merocyanines have been investigated. There have been found two components in the transfer of charge: fast and slow, which correspond to different conformational states of the carbon chain in merocyanines. It was found that the main photoluminescence of the studied molecular solutions of merocyanines by its nature is similar to the exciplex luminescence, as a manifestation of resonant and charge transfer interaction in an excited state. The lifetime in this state is about 2000 ps.

  1. Photoinduced electron-transfer from pi-conjugated polymers onto buckminsterfullerene, fulleroids, and methanofullerenes

    NARCIS (Netherlands)

    Janssen, R. A. J.; Hummelen, J. C.; Lee, Kwanghee; Pakbaz, K.; Sariciftci, N. S.; Heeger, A. J.; Wudl, F

    1995-01-01

    We present near-steady-state photoinduced absorption (PIA), photoluminescence, and light-induced electron spin resonance (LESR) studies on photoinduced electron transfer reactions from poly(bis-2,5-epi-cholestanoxy-1,4-phenylene vinylene) (BeCHA-PPV) as a donor to Buckminsterfullerene (C60) and a

  2. 77 FR 10373 - Greenhouse Gas Reporting Program: Electronics Manufacturing: Revisions to Heat Transfer Fluid...

    Science.gov (United States)

    2012-02-22

    ... Greenhouse Gas Reporting Program: Electronics Manufacturing: Revisions to Heat Transfer Fluid Provisions... technical revisions to the electronics manufacturing source category of the Greenhouse Gas Reporting Rule... final rule will also be available through the WWW on the EPA's Greenhouse Gas Reporting Program Web site...

  3. Potential for direct interspecies electron transfer in methanogenic wastewater digester aggregates

    DEFF Research Database (Denmark)

    Morita, Masahiko; Malvankar, Nikhil S; Franks, Ashley E

    2011-01-01

    Mechanisms for electron transfer within microbial aggregates derived from an upflow anaerobic sludge blanket reactor converting brewery waste to methane were investigated in order to better understand the function of methanogenic consortia. The aggregates were electrically conductive, with conduc...... for electron exchange in some methanogenic systems....

  4. Fast solar electrons, interplanetary plasma and km-wave type-III radio bursts observed from the IMP-6 spacecraft

    International Nuclear Information System (INIS)

    Alvarez, H.; Lin, R.P.

    1975-01-01

    IMP-6 spacecraft observations of low frequency radio emission, fast electrons, and solar wind plasma are used to examine the dynamics of the fast electron streams which generate solar type-III radio bursts. Of twenty solar electron events observed between April 1971 and August 1972, four were found to be amenable to detailed analysis. Observations of the direction of arrival of the radio emission at different frequencies were combined with the solar wind density and velocity measurements at 1 AU to define an Archimedean spiral trajectory for the radio burst exciter. The propagation characteristics of the exciter and of the fast electrons observed at 1 AU were then compared. It is found that: (1) the fast electrons excite the radio emission at the second harmonic; (2) the total distance travelled by the electrons was between 30 and 70% longer than the length of the smooth spiral defined by the radio observations; (3) this additional distance travelled is the result of scattering of the electrons in the interplanetary medium; (4) the observations are consistent with negligible true energy loss by the fast electrons.(Auth.)

  5. Note: Measurements of fast electrons in the TORE-SUPRA tokamak by means of modified Cherenkov-type diamond detector

    Energy Technology Data Exchange (ETDEWEB)

    Jakubowski, L.; Sadowski, M. J.; Zebrowski, J.; Rabinski, M.; Jakubowski, M. J.; Malinowski, K.; Mirowski, R. [National Centre for Nuclear Research (NCBJ), 7 Andrzeja Soltana Str., 05-400 Otwock (Poland); Lotte, Ph.; Goniche, M.; Gunn, J.; Colledani, G.; Pascal, J.-Y.; Basiuk, V. [CEA, IRFM, F-13108 Saint Paul-lez-Durance (France)

    2013-01-15

    The Note reports on experimental studies of ripple born fast electrons within the TORE-SUPRA facility, which were performed by means of a modified measuring head equipped with diamond detectors designed especially for recording the electron-induced Cherenkov radiation. There are presented signals produced by fast electrons in the TORE-SUPRA machine, which were recorded during two experimental campaigns performed in 2010. Shapes of these electron-induced signals are considerably different from those observed during the first measurements carried out by the prototype Cherenkov probe in 2008. An explanation of the observed differences is given.

  6. Note: Measurements of fast electrons in the TORE-SUPRA tokamak by means of modified Cherenkov-type diamond detector

    International Nuclear Information System (INIS)

    Jakubowski, L.; Sadowski, M. J.; Zebrowski, J.; Rabinski, M.; Jakubowski, M. J.; Malinowski, K.; Mirowski, R.; Lotte, Ph.; Goniche, M.; Gunn, J.; Colledani, G.; Pascal, J.-Y.; Basiuk, V.

    2013-01-01

    The Note reports on experimental studies of ripple born fast electrons within the TORE-SUPRA facility, which were performed by means of a modified measuring head equipped with diamond detectors designed especially for recording the electron-induced Cherenkov radiation. There are presented signals produced by fast electrons in the TORE-SUPRA machine, which were recorded during two experimental campaigns performed in 2010. Shapes of these electron-induced signals are considerably different from those observed during the first measurements carried out by the prototype Cherenkov probe in 2008. An explanation of the observed differences is given.

  7. Recent experimental progress in the study of electron and proton beating for fast ignition

    International Nuclear Information System (INIS)

    Key, M. H.; Akli, K.; Beg, F.; Chen, M. H.; Chen, Z.; Chung, H. K.; Fournier, K.; Freeman, R. R.; Green, J. S.; Gu, P.; Gregori, J.; Habara, H.; Hatchett, S. P.; Hey, D.; Hill, J. M.; Izawa, Y.; King, J. A.; Kitagawa, Y.; Kodama, R.; Koch, J. A.; Lancaster, K.; Lasinski, B. F.; Langdon, B.; MacKinnon, A. J.; Lei, A.; Moon, S. J.; Murphy, C. D.; Norreys, P. A.; Park, H. S.; Patel, N.; Patel, P.; Pasley, J.; Snavely, R. A.; Stephens, R. B.; Stoeckl, C.; Tabak, M.; Tampo, M.; Theobold, W.; Tanaka, K. A.; Town, R. J. P.; Toyama, Y.; Tsutsumi, T.; Wilks, S. C.; Yabuuchi, T.; Zhang, B.; Zheng, J.

    2005-01-01

    The results of recent collaborative experimental campaigns at the RAL PW and 100 TW and Gekko PW laser facilities, which have extended our understanding of electron and proton heating for fast ignition are presented. Heating by electrons has been measured by imaging Cu Ka fluorescence, from crystal and single hit CCD spectroscopy of Cu K shell emission, from two color XUV imaging (68eV and 270 eV) and from streaked 68eV imaging. Heating in solid foil targets, ultra- low mass foil targets and cone targets coupled to fibers and other FI surrogates has been studied using 0.5 to 10 ps pulse duration and powers up to 1 PW. Cone coupling to an imploded plasma has been examined using Cu Ka to diagnose the electron flux in the imploded material. Heating by focused proton beams generated at the concave inside surface of a hemi shell has been studied with similar diagnostic methods. Temperatures at the rear surface of proton heated solid foils have exceeded those produced by direct electron heating. Variation of heating with depth and the transverse pattern of heating have been measured. The spatial distribution of electron flux in a Cu hemi- shell used as a proton source has been determined by imaging Ka fluorescence. Conversion efficiency to protons has been measured from radio-chromic film data. Conclusions from the experiments, links to theoretical understanding and relevance to fast ignition are outlined. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. (Author)

  8. 77 FR 30923 - Electronic Fund Transfers (Regulation E)

    Science.gov (United States)

    2012-05-24

    ... similar to a debit card that is linked to a traditional checking account. The Bureau is particularly interested in learning more about this product, including its costs, benefits, and risks to consumers. The... methods: Electronic: http://www.regulations.gov . Follow the instructions for submitting comments. Mail...

  9. Interspecies electron transfer in methanogenic propionate degrading consortia

    NARCIS (Netherlands)

    Bok, de F.A.M.; Plugge, C.M.; Stams, A.J.M.

    2004-01-01

    Propionate is a key intermediate in the conversion of complex organic matter under methanogenic conditions. Oxidation of this compound requires obligate syntrophic consortia of acetogenic proton- and bicarbonate reducing bacteria and methanogenic archaea. Although H-2 acts as an electron-carrier in

  10. Tests of the heat transfer characteristic of air cooler during cooling by natural convection of the Fast Breeder Reactor plants

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-08-15

    The purpose of this study is to confirm the heat transfer characteristics of the air cooler (AC) of the Fast Breeder Reactor(FBR) which has a function to remove the residual heat of the reactor by heat exchange between sodium and air in natural convection region if electric power would be lost. In order to confirm the characteristics of the AC installed in the FBR plant, the heat transfer test by using the AC which is installed in the sodium test loop owned by Toshiba Corporation has been planned. In this study, the heat transfer characteristic tests were performed by using the AC in sodium test loop, and the CFD analyses were conducted to evaluate the test results and the heat transfer characteristics of the plant scale AC at the condition of natural convection. In addition, the elemental tests to confirm the influence of the heat transfer tube placement by using the heat transfer tube of the same specification as the AC of Monju were performed. (author)

  11. Proton probe measurement of fast advection of magnetic fields by hot electrons

    International Nuclear Information System (INIS)

    Willingale, L; Thomas, A G R; Nilson, P M; Kaluza, M C; Dangor, A E; Evans, R G; Fernandes, P; Haines, M G; Kamperidis, C; Kingham, R J; Ridgers, C P; Sherlock, M; Wei, M S; Najmudin, Z; Krushelnick, K; Bandyopadhyay, S; Notley, M; Minardi, S; Rozmus, W; Tatarakis, M

    2011-01-01

    A laser generated proton beam was used to measure the megagauss strength self-generated magnetic fields from a nanosecond laser interaction with an aluminum target. At intensities of 10 15 W cm −2 , the significant hot electron production and strong heat fluxes result in non-local transport becoming important to describe the magnetic field dynamics. Two-dimensional implicit Vlasov–Fokker–Planck modeling shows that fast advection of the magnetic field from the focal region occurs via the Nernst effect at significantly higher velocities than the sound speed, v N /c s ≈ 10.

  12. Slowing of a fast electron beam in a plasma in an intense electromagnetic wave

    Energy Technology Data Exchange (ETDEWEB)

    Karapetyan, R.V.; Fedorov, M.V.

    1980-01-01

    The slowing of a fast electron beam as it penetrates into a plasma in a strong external electromagnetic field is studied. The effective collision frequency ..nu../sub p/ which is responsible for the slowing is derived in the dipole approximation; many-photon stimulated bremsstrahlung and inverse bremsstrahlung are taken into account. The asymptotic behavior of ..nu../sub p/ in strong wave fields E/sub 0/ is found. The results show that ..nu../sub p/ falls off with increasing E/sub 0/, because of a decrease in the frequency of collisions with plasma ions proportional to E/sub 0//sup -1/.

  13. Effects of resistive magnetic field on fast electron divergence measured in experiment

    Czech Academy of Sciences Publication Activity Database

    Yang, H.X.; Zhuo, H.B.; Ma, Y.Y.; Xu, H.; Yu, T.P.; Zou, D.B.; Ge, Z.Y.; Xu, B.B.; Zhu, Q.J.; Shao, F.Q.; Borghesi, Marco

    2015-01-01

    Roč. 57, č. 2 (2015), s. 025011 ISSN 0741-3335 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279 Institutional support: RVO:68378271 Keywords : fast electron * divergence measument * resistive magnetic field * laser-plasma interactions * short-pulse * acceleration Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.404, year: 2015

  14. The behavior of exciplex decay processes and interplay of radiationless transition and preliminary reorganization mechanisms of electron transfer in loose and tight pairs of reactants.

    Science.gov (United States)

    Kuzmin, Michael G; Soboleva, Irina V; Dolotova, Elena V

    2007-01-18

    Exciplex emission spectra and rate constants of their decay via internal conversion and intersystem crossing are studied and discussed in terms of conventional radiationless transition approach. Exciplexes of 9-cyanophenanthrene with 1,2,3-trimethoxybenzene and 1,3,5-trimethoxybenzene were studied in heptane, toluene, butyl acetate, dichloromethane, butyronitrile, and acetonitrile. A better description of spectra and rate constants is obtained using 0-0 transition energy and Gauss broadening of vibrational bands rather than the free energy of electron transfer and reorganization energy. The coincidence of parameters describing exciplex emission spectra and dependence of exciplex decay rate constants on energy gap gives the evidence of radiationless quantum transition mechanism rather than thermally activated medium reorganization mechanism of charge recombination in exciplexes and excited charge transfer complexes (contact radical ion pairs) as well as in solvent separated radical ion pairs. Radiationless quantum transition mechanism is shown to provide an appropriate description also for the main features of exergonic excited-state charge separation reactions if fast mutual transformations of loose and tight pairs of reactants are considered. In particular, very fast electron transfer (ET) in tight pairs of reactants with strong electronic coupling of locally excited and charge transfer states can prevent the observation of an inverted region in bimolecular excited-state charge separation even for highly exergonic reactions.

  15. Effects of electron-transfer chemical modification on the electrical characteristics of graphene

    International Nuclear Information System (INIS)

    Fan Xiaoyan; Tanigaki, Katsumi; Nouchi, Ryo; Yin Lichang

    2010-01-01

    Because of the large reactivity of single layer graphene to electron-transfer chemistries, 4-nitrobenzene diazonium tetrafluoroborate is employed to modify the electrical properties of graphene field-effect transistors. After modification, the transfer characteristics of chemically modified graphene show a reduction in the minimum conductivity, electron-hole mobility asymmetry, a decrease in the electron/hole mobility, and a positive shift of the charge neutrality point with broadening of the minimum conductivity region. These phenomena are attributed to a dediazoniation reaction and the adsorbates on the graphene surface.

  16. Effects of electron-transfer chemical modification on the electrical characteristics of graphene

    Energy Technology Data Exchange (ETDEWEB)

    Fan Xiaoyan; Tanigaki, Katsumi [Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan); Nouchi, Ryo [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8578 (Japan); Yin Lichang, E-mail: nouchi@sspns.phys.tohoku.ac.jp [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2010-11-26

    Because of the large reactivity of single layer graphene to electron-transfer chemistries, 4-nitrobenzene diazonium tetrafluoroborate is employed to modify the electrical properties of graphene field-effect transistors. After modification, the transfer characteristics of chemically modified graphene show a reduction in the minimum conductivity, electron-hole mobility asymmetry, a decrease in the electron/hole mobility, and a positive shift of the charge neutrality point with broadening of the minimum conductivity region. These phenomena are attributed to a dediazoniation reaction and the adsorbates on the graphene surface.

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

    International Nuclear Information System (INIS)

    Zhang, Yan; Hao, Huilian; Wang, Linlin

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-30

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

  19. Population of nitrogen molecule electron states and structure of the fast ionization wave

    CERN Document Server

    Pancheshnyi, S V; Starikovskii, A Y

    1999-01-01

    The excitation of N sub 2 (C sup 3 supPI sub u , nu=0) and N sup + sub 2 (B sup 2 supSIGMA sup + sub u , nu=0) electron states has been studied by using a time-resolved emission spectroscopy technique. To excite the above states, the nanosecond, high-voltage, periodic impulsed discharge at low pressures in the form of the fast ionization wave (FIW) was used. The electron concentration and the average energy, electric field were found on the basis of experimental data. The spacial-temporal structure of the FIW front was investigated. It has been shown that the generation of the required electron concentration, as well as the electron level population take place behind the FIW front in residual fields. Sections corresponding to the 'electric' and 'luminous' FIW fronts are essentially separated in space. The proposed modelling electron energy distribution function describes qualitatively general regularities of the breakdown propagation in the whole range of parameters under study. (author)

  20. Flat Graphene-Enhanced Electron Transfer Involved in Redox Reactions.

    Science.gov (United States)

    Pan, Meilan; Zhang, Yanyang; Shan, Chao; Zhang, Xiaolin; Gao, Guandao; Pan, Bingcai

    2017-08-01

    Graphene is easily warped in the out-of-plane direction because of its high in-plane Young's modulus, and exploring the influence of wrinkled graphene on its properties is essential for the design of graphene-based materials for environmental applications. Herein, we prepared wrinkled graphene (WGN-1 and WGN-2) by thermal treatment and compared their electrochemical properties with those of flat graphene nanosheets (FGN). FGN exhibit activities that are much better than those of wrinkled graphene nanosheets (WGN), not only in the electrochemical oxidation of methylene blue (MB) but also in the electrochemical reduction of nitrobenzene (NB). Transformation ratios of MB and NB in FGN, WGN-1, and WGN-2 were 97.5, 80.1, and 57.9% and 94.6, 92.1, and 81.2%, respectively. Electrochemical impedance spectroscopy and the surface resistance of the graphene samples increased in the following order: FGN reaction charges transfer faster across the reaction interfaces and along the surface of FGN than that of WGN, and wrinkles restrict reaction charge transfer and reduce the reaction rates. This study reveals that the morphology of the graphene (flat or wrinkle) greatly affects redox reaction activities and may have important implications for the design of novel graphene-based nanostructures and for our understanding of graphene wrinkle-dependent redox reactions in environmental processes.

  1. Properties of the transfer matrices of deflecting magnet systems for free electron laser

    International Nuclear Information System (INIS)

    Takao, Masaru

    1993-01-01

    The oscillation of the free electron laser (FEL) requires the high current and low emittance electron beam. The beam transport system should be achromatic and isochronous to preserve the brightness and the emittance of the electron beam. In this paper we clarify the algebraic properties of the transfer matrices of the magnetic deflection system, which is a key component in the beam transport line. (author)

  2. Selection rules for electron transfer to the continuum in ion-atom collision

    Energy Technology Data Exchange (ETDEWEB)

    Barrachina, R.O.; Bernardi, G.C.; Garibotti, C.R.

    1985-10-01

    We consider the process of electron transfer to the in first order Born approximation. We analyse the expansion of the double-differential cross section in series of electron velocity and ejection angle. We found that the coefficients obey precise selection rules. We discuss the relation of these rules, which predict an asymmetric shape for the electron loss to the continuum cusp, with the interpretation of recent experimental results.

  3. Challenges in reduction of dinitrogen by proton and electron transfer.

    Science.gov (United States)

    van der Ham, Cornelis J M; Koper, Marc T M; Hetterscheid, Dennis G H

    2014-08-07

    Ammonia is an important nutrient for the growth of plants. In industry, ammonia is produced by the energy expensive Haber-Bosch process where dihydrogen and dinitrogen form ammonia at a very high pressure and temperature. In principle one could also reduce dinitrogen upon addition of protons and electrons similar to the mechanism of ammonia production by nitrogenases. Recently, major breakthroughs have taken place in our understanding of biological fixation of dinitrogen, of molecular model systems that can reduce dinitrogen, and in the electrochemical reduction of dinitrogen at heterogeneous surfaces. Yet for efficient reduction of dinitrogen with protons and electrons major hurdles still have to be overcome. In this tutorial review we give an overview of the different catalytic systems, highlight the recent breakthroughs, pinpoint common grounds and discuss the bottlenecks and challenges in catalytic reduction of dinitrogen.

  4. Electronic energy transfer through non-adiabatic vibrational-electronic resonance. II. 1D spectra for a dimer

    Science.gov (United States)

    Tiwari, Vivek; Jonas, David M.

    2018-02-01

    Vibrational-electronic resonance in photosynthetic pigment-protein complexes invalidates Förster's adiabatic framework for interpreting spectra and energy transfer, thus complicating determination of how the surrounding protein affects pigment properties. This paper considers the combined effects of vibrational-electronic resonance and inhomogeneous variations in the electronic excitation energies of pigments at different sites on absorption, emission, circular dichroism, and hole-burning spectra for a non-degenerate homodimer. The non-degenerate homodimer has identical pigments in different sites that generate differences in electronic energies, with parameters loosely based on bacteriochlorophyll a pigments in the Fenna-Matthews-Olson antenna protein. To explain the intensity borrowing, the excited state vibrational-electronic eigenvectors are discussed in terms of the vibrational basis localized on the individual pigments, as well as the correlated/anti-correlated vibrational basis delocalized over both pigments. Compared to those in the isolated pigment, vibrational satellites for the correlated vibration have the same frequency and precisely a factor of 2 intensity reduction through vibrational delocalization in both absorption and emission. Vibrational satellites for anti-correlated vibrations have their relaxed emission intensity reduced by over a factor 2 through vibrational and excitonic delocalization. In absorption, anti-correlated vibrational satellites borrow excitonic intensity but can be broadened away by the combination of vibronic resonance and site inhomogeneity; in parallel, their vibronically resonant excitonic partners are also broadened away. These considerations are consistent with photosynthetic antenna hole-burning spectra, where sharp vibrational and excitonic satellites are absent. Vibrational-excitonic resonance barely alters the inhomogeneously broadened linear absorption, emission, and circular dichroism spectra from those for a

  5. Designed Surface Residue Substitutions in [NiFe] Hydrogenase that Improve Electron Transfer Characteristics

    Directory of Open Access Journals (Sweden)

    Isaac T. Yonemoto

    2015-01-01

    Full Text Available Photobiological hydrogen production is an attractive, carbon-neutral means to convert solar energy to hydrogen. We build on previous research improving the Alteromonas macleodii “Deep Ecotype” [NiFe] hydrogenase, and report progress towards creating an artificial electron transfer pathway to supply the hydrogenase with electrons necessary for hydrogen production. Ferredoxin is the first soluble electron transfer mediator to receive high-energy electrons from photosystem I, and bears an electron with sufficient potential to efficiently reduce protons. Thus, we engineered a hydrogenase-ferredoxin fusion that also contained several other modifications. In addition to the C-terminal ferredoxin fusion, we truncated the C-terminus of the hydrogenase small subunit, identified as the available terminus closer to the electron transfer region. We also neutralized an anionic patch surrounding the interface Fe-S cluster to improve transfer kinetics with the negatively charged ferredoxin. Initial screening showed the enzyme tolerated both truncation and charge neutralization on the small subunit ferredoxin-binding face. While the enzyme activity was relatively unchanged using the substrate methyl viologen, we observed a marked improvement from both the ferredoxin fusion and surface modification using only dithionite as an electron donor. Combining ferredoxin fusion and surface charge modification showed progressively improved activity in an in vitro assay with purified enzyme.

  6. Charge transfer dynamics from adsorbates to surfaces with single active electron and configuration interaction based approaches

    Energy Technology Data Exchange (ETDEWEB)

    Ramakrishnan, Raghunathan, E-mail: r.ramakrishnan@unibas.ch [Institute of Physical Chemistry, National Center for Computational Design and Discovery of Novel Materials (MARVEL), Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Nest, Mathias [Theoretische Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching (Germany)

    2015-01-13

    Highlights: • We model electron dynamics across cyano alkanethiolates attached to gold cluster. • We present electron transfer time scales from TD-DFT and TD-CI based simulations. • Both DFT and CI methods qualitatively predict the trend in time scales. • TD-CI predicts the experimental relative time scale very accurately. - Abstract: We employ wavepacket simulations based on many-body time-dependent configuration interaction (TD-CI), and single active electron theories, to predict the ultrafast molecule/metal electron transfer time scales, in cyano alkanethiolates bonded to model gold clusters. The initial states represent two excited states where a valence electron is promoted to one of the two virtual π{sup ∗} molecular orbitals localized on the cyanide fragment. The ratio of the two time scales indicate the efficiency of one charge transfer channel over the other. In both our one-and many-electron simulations, this ratio agree qualitatively with each other as well as with the previously reported experimental time scales (Blobner et al., 2012), measured for a macroscopic metal surface. We study the effect of cluster size and the description of electron correlation on the charge transfer process.

  7. The influence of inhomogeneities on the dose distribution of fast electrons in radiotherapy

    International Nuclear Information System (INIS)

    Windemuth, M.

    1985-01-01

    Simple models are used to make a principal comparison between measured fast-electron dose distributions behind tissue inhomogeneities and those calculated by means of an irradiation planning system. The different organs were represented by water (for muscle), by cork (for the lungs) and by graphite (for bone). Corresponding to their density, inhomogeneities result, in principle, in a dose shift to a greater or smaller body depth which is correctly considered by the irradiation planning system. However, electron scattering transversal to beam direction will occur behind inhomogeneity edges which, in general, are not covered by the irradiation planning system, but which result in dose distributions deviating strongly from those expected as due to the shift. This is the reason for the limited accuracy of irradiation planning systems in complicated inhomogeneity distribution. The thesis demonstrates those cases which justify irradiation planning and those cases where they are not a reliable basis for irradiation. (orig./HP) [de

  8. Electron cyclotron measurements with the fast scanning heterdyne radiometer on the tokamak fusion test reactor

    International Nuclear Information System (INIS)

    Taylor, G.; Efthimion, P.C.; McCarthy, M.P.; Fredd, E.A.; Cutler, R.C.

    1986-01-01

    Three fast scanning heterodyne receivers, swept between 75-110 GHz, 110-170 GHz, and 170-210 GHz, have measured electron cyclotron emission on the horizontal midplane of the tokamak fusion test reactor (TFTR) plasma. A second harmonic microwave mixer in the 170-210 GHz receiver allows the use of a 75-110 GHz backward wave oscillator as a swept local oscillator. Electron temperature profile evolution data with a time resolution of 2 msec and a profile acquisition rate of 250 Hz are presented for gas-fuelled and pellet-fuelled ohmic and neutral beam heated plasmas with toroidal fields up to 5.2 tesla. Recent results from a swept mode absolute calibration technique which can improve the accuracy and data collection efficiency during in-situ calibration are also presented

  9. 50 MeV Run of the IOTA / FAST Electron Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Edstrom Jr., D.; et al.

    2017-02-02

    The low-energy section of the photoinjector-based electron linear accelerator at the Fermilab Accelerator Science & Technology (FAST) facility was recently commissioned to an energy of 50 MeV. This linear accelerator relies primarily upon pulsed SRF acceleration and an optional bunch compressor to produce a stable beam within a large operational regime in terms of bunch charge, total average charge, bunch length, and beam energy. Various instrumentation was used to characterize fundamental properties of the electron beam including the intensity, stability, emittance, and bunch length. While much of this instrumentation was commissioned in a 20 MeV running period prior, some (including a new Martin- Puplett interferometer) was in development or pending installation at that time. All instrumentation has since been recommissioned over the wide operational range of beam energies up to 50 MeV, intensities up to 4 nC/pulse, and bunch structures from ~1 ps to more than 50 ps in length.

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

    KAUST Repository

    Li, Jingrui

    2015-07-29

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

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

    KAUST Repository

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

    2015-01-01

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

  12. Femtosecond dynamics of electron transfer in a neutral organic mixed-valence compound

    International Nuclear Information System (INIS)

    Maksimenka, Raman; Margraf, Markus; Koehler, Juliane; Heckmann, Alexander; Lambert, Christoph; Fischer, Ingo

    2008-01-01

    In this article we report a femtosecond time-resolved transient absorption study of a neutral organic mixed-valence (MV) compound with the aim to gain insight into its charge-transfer dynamics upon optical excitation. The back-electron transfer was investigated in five different solvents, toluene, dibutyl ether, methyl-tert-butyl ether (MTBE), benzonitrile and n-hexane. In the pump step, the molecule was excited at 760 nm and 850 nm into the intervalence charge-transfer band. The resulting transients can be described by two time constant. We assign one time constant to the rearrangement of solvent molecules in the charge-transfer state and the second time constant to back-electron transfer to the electronic ground state. Back-electron transfer rates range from 1.5 x 10 12 s -1 in benzonitrile through 8.3 x 10 11 s -1 in MTBE, around 1.6 x 10 11 s -1 in dibutylether and toluene and to 3.8 x 10 9 s -1 in n-hexane

  13. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter

    International Nuclear Information System (INIS)

    Pisani, F.

    2000-02-01

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  14. Enhanced Electronic Properties of SnO2 via Electron Transfer from Graphene Quantum Dots for Efficient Perovskite Solar Cells.

    Science.gov (United States)

    Xie, Jiangsheng; Huang, Kun; Yu, Xuegong; Yang, Zhengrui; Xiao, Ke; Qiang, Yaping; Zhu, Xiaodong; Xu, Lingbo; Wang, Peng; Cui, Can; Yang, Deren

    2017-09-26

    Tin dioxide (SnO 2 ) has been demonstrated as an effective electron-transporting layer (ETL) for attaining high-performance perovskite solar cells (PSCs). However, the numerous trap states in low-temperature solution processed SnO 2 will reduce the PSCs performance and result in serious hysteresis. Here, we report a strategy to improve the electronic properties in SnO 2 through a facile treatment of the films with adding a small amount of graphene quantum dots (GQDs). We demonstrate that the photogenerated electrons in GQDs can transfer to the conduction band of SnO 2 . The transferred electrons from the GQDs will effectively fill the electron traps as well as improve the conductivity of SnO 2 , which is beneficial for improving the electron extraction efficiency and reducing the recombination at the ETLs/perovskite interface. The device fabricated with SnO 2 :GQDs could reach an average power conversion efficiency (PCE) of 19.2 ± 1.0% and a highest steady-state PCE of 20.23% with very little hysteresis. Our study provides an effective way to enhance the performance of perovskite solar cells through improving the electronic properties of SnO 2 .

  15. Final Aperture Superposition Technique applied to fast calculation of electron output factors and depth dose curves

    International Nuclear Information System (INIS)

    Faddegon, B.A.; Villarreal-Barajas, J.E.

    2005-01-01

    The Final Aperture Superposition Technique (FAST) is described and applied to accurate, near instantaneous calculation of the relative output factor (ROF) and central axis percentage depth dose curve (PDD) for clinical electron beams used in radiotherapy. FAST is based on precalculation of dose at select points for the two extreme situations of a fully open final aperture and a final aperture with no opening (fully shielded). This technique is different than conventional superposition of dose deposition kernels: The precalculated dose is differential in position of the electron or photon at the downstream surface of the insert. The calculation for a particular aperture (x-ray jaws or MLC, insert in electron applicator) is done with superposition of the precalculated dose data, using the open field data over the open part of the aperture and the fully shielded data over the remainder. The calculation takes explicit account of all interactions in the shielded region of the aperture except the collimator effect: Particles that pass from the open part into the shielded part, or visa versa. For the clinical demonstration, FAST was compared to full Monte Carlo simulation of 10x10,2.5x2.5, and 2x8 cm 2 inserts. Dose was calculated to 0.5% precision in 0.4x0.4x0.2 cm 3 voxels, spaced at 0.2 cm depth intervals along the central axis, using detailed Monte Carlo simulation of the treatment head of a commercial linear accelerator for six different electron beams with energies of 6-21 MeV. Each simulation took several hours on a personal computer with a 1.7 Mhz processor. The calculation for the individual inserts, done with superposition, was completed in under a second on the same PC. Since simulations for the pre calculation are only performed once, higher precision and resolution can be obtained without increasing the calculation time for individual inserts. Fully shielded contributions were largest for small fields and high beam energy, at the surface, reaching a maximum

  16. Two-dimensional CsPbBr3/PCBM heterojunctions for sensitive, fast and flexible photodetectors boosted by charge transfer

    Science.gov (United States)

    Shen, Yalong; Yu, Dejian; Wang, Xiong; Huo, Chengxue; Wu, Ye; Zhu, Zhengfeng; Zeng, Haibo

    2018-02-01

    Inorganic halide perovskites exhibited promising potentials for high-performance wide-band photodetectors (PDs) due to their high light absorption coefficients, long carrier diffusion length and wide light absorption ranges. Here, we report two-dimensional (2D) CsPbBr3/PCBM heterojunctions for sensitive, fast and flexible PDs, whose performances can be greatly boosted by the charge transfer through the energy-aligned interface. The 2D CsPbBr3 nanosheets with high crystallinity were fabricated via a simple solution-process at room temperature, and then assembled into flexible heterojunctions films with polymerphenyl-C61-butyric acid methyl ester (PCBM). Significantly, the efficient and fast charge transfer at the heterojunctions interface was evidenced by the obvious photoluminescence quenching and variation of recombination dynamics. Subsequently, such heterojunctions PD exhibited an enhanced responsivity of 10.85 A W-1 and an ultrahigh detectivity of 3.06 × 1013 Jones. In addition, the PD shows a broad linear dynamic range of 73 dB, a fast response speed with rise time of 44 μs and decay time of 390 μs, respectively. Moreover, the PD lying on polyethylene terephthalate substrates exhibited an outstanding mechanical flexibility and a robust electrical stability. These results could provide a new avenue for integration of 2D perovskites and organic functional materials and for high-performance flexible PDs.

  17. Nanoscale and single-molecule interfacial electron transfer

    DEFF Research Database (Denmark)

    Hansen, Allan Glargaard; Wackerbarth, Hainer; Nielsen, Jens Ulrik

    2003-01-01

    for comprehensive later theoretical work and data interpretation in many areas of chemistry, electrochemistry, and biology. We discuss here some new areas of theoretical electrochemical ET science, with focus on nanoscale electrochemical and bioelectrochemical sciences. Particular attention is given to in situ...... scanning tunneling microscopy (STM) and single-electron tunneling (SET, or Coulomb blockade) in electrochemical. systems directly in aqueous electrolyte solution and at room temperature. We illustrate the new theoretical formalism and its perspectives by recent cases of electrochemical SET, negative...... differential resistance patterns, and by ET dynamics of organized assemblies of biological macromolecules, such as redox metalloproteins and oligonucleotides on single-crystal Au(III)-electrode surfaces....

  18. Correlation between biological activity and electron transferring of bovine liver catalase: Osmolytes effects

    International Nuclear Information System (INIS)

    Tehrani, H. Sepasi; Moosavi-Movahedi, A.A.; Ghourchian, H.

    2013-01-01

    Highlights: • Proline increases ET in Bovine Liver Catalase (BLC) whereas histidine decreases it. • Proline also increased the biological activity, whereas histidine decreased it. • Electron transferring and biological activity for BLC are directly correlated. • Proline causes favorable ET for BLC shown by positive E 1/2 (E°′) and negative ΔG. • Histidine makes ET unfavorable for BLC, manifested by E 1/2 (E°′) 0. -- Abstract: Catalase is a crucial antioxidant enzyme that protects life against detrimental effects of H 2 O 2 by disproportionating it into water and molecular oxygen. Effect of proline as a compatible and histidine as a non compatible osmolyte on the electron transferring and midpoint potential of catalase has been investigated. Proline increases the midpoint potential (ΔE m > 0), therefore causing the ΔG ET to be less positive and making the electron transfer reaction more facile whereas histidine decreases the E m (ΔE m ET , thereby rendering the electron transfer reaction less efficient. These results indicate the inhibitory effect of histidine evident by a −37% decrease in the cathodic peak current compared to 16% increase in the case of proline indicative of activation. The insight paves the tedious way towards our ultimate goal of elucidating a correlation between biological activity and electron transferring

  19. A Simple Transmission Electron Microscopy Method for Fast Thickness Characterization of Suspended Graphene and Graphite Flakes.

    Science.gov (United States)

    Rubino, Stefano; Akhtar, Sultan; Leifer, Klaus

    2016-02-01

    We present a simple, fast method for thickness characterization of suspended graphene/graphite flakes that is based on transmission electron microscopy (TEM). We derive an analytical expression for the intensity of the transmitted electron beam I 0(t), as a function of the specimen thickness t (tgraphite). We show that in thin graphite crystals the transmitted intensity is a linear function of t. Furthermore, high-resolution (HR) TEM simulations are performed to obtain λ for a 001 zone axis orientation, in a two-beam case and in a low symmetry orientation. Subsequently, HR (used to determine t) and bright-field (to measure I 0(0) and I 0(t)) images were acquired to experimentally determine λ. The experimental value measured in low symmetry orientation matches the calculated value (i.e., λ=225±9 nm). The simulations also show that the linear approximation is valid up to a sample thickness of 3-4 nm regardless of the orientation and up to several ten nanometers for a low symmetry orientation. When compared with standard techniques for thickness determination of graphene/graphite, the method we propose has the advantage of being simple and fast, requiring only the acquisition of bright-field images.

  20. The effects of fast electron radiation on the development of Trogoderma granarium Everts (Coleoptera:Dermestidae)

    International Nuclear Information System (INIS)

    Szlendak, E.; Davis, R.

    1989-01-01

    Effects of fast electron radiation exposures (range from 0 to 1.00 kGy) on the developmental stages of the khapra beetle, Trogoderma granarium Everts, were studied. Adults were very sensitive and were sterilized when irradiated at 21.6 Gy or higher. Treated by lower doses, females laid some eggs, although their viability was very low. Pupal development was stopped with 600 Gy and adults that emerged from pupae treated by lower doses were sterile or laid unviable eggs. No F 1 progeny were developed when pupae were treated by 5 Gy, the lowest dose applied. Larvae did not develop after treatment with 50 Gy or higher. Postradiation ovipositional behavior of T.granarium was observed in two different treatment situations. One group of treated adults was reared in cages with a supply of food. A second group of treated adults was kept without food. Feeding appeared to be an important ovipositional factor. Treatment with fast electrons could provide a convenient and efficient method for reducing populations of the khapra beetle in stored grain. (author)

  1. Preparation of high performance NBR/HNTs nanocomposites using an electron transferring interaction method

    Science.gov (United States)

    Yang, Shuyan; Zhou, Yanxue; Zhang, Peng; Cai, Zhuodi; Li, Yangping; Fan, Hongbo

    2017-12-01

    Interfacial interaction is one of the key factors to improve comprehensive properties of polymer/inorganic filler nanocomposites. In this work, a new interfacial interaction called electron transferring interaction is reported in the nitrile-butadiene rubber/halloysite nanotubes (NBR/HNTs) nanocomposites. The X-ray photoelectron spectroscopy (XPS) and in-situ controlling temperature Fourier transform infrared spectroscopy (FTIR) have confirmed that electrons of electron-rich -CN groups in NBR can transfer to the electron-deficiency aluminum atoms of HNTs, which packs a part of NBR molecules onto the surface of HNTs to form bound rubber and stabilize the homogeneous dispersion of HNTs with few agglomeration as revealed by scanning electron microscope (SEM) and dynamic mechanical analysis (DMA) performances, even at high HNTs addition, resulting in high light transmittance. The tensile strength of NBR/30wt%HNTs nanocomposites is about 291% higher than pure NBR, without sacrificing the elongation at break.

  2. Study of charge distribution and atomic arrangement at interfaces using fast electron scattering

    International Nuclear Information System (INIS)

    Hugsted, B.

    1993-01-01

    The principle of fast electron scattering at a potential step has been elucidated. It has been shown that electrons scattered in the near forward direction bring significant information of the potential step at an interface. Experiments have been shown where the interface between AlAs and GaAs in a MBE-grown sample is visible as a bright or dark line in the image, depending on the location of the dark field aperture. The asymmetric intensity distribution in reciprocal space has been shown using an improved phase grating approximation. The author puts forward the argument that neither the normal dark-field technique in the electron microscope nor the usual reciprocal space calculation techniques for image simulation are suited for this type of experiments. This argumentation is followed by the proposal of an improved dark field technique with high resolution in reciprocal space, and the development of a calculation technique (performed in real space) that is suitable for the calculation of electron scattering from non-periodic objects. 28 refs

  3. Activators generated by electron transfer for atom transfer radical polymerization of styrene in the presence of mesoporous silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Khezri, Khezrollah, E-mail: kh.khezri@ut.ac.ir [School of Chemistry, University College of Science, University of Tehran, PO Box 14155-6455, Tehran (Iran, Islamic Republic of); Roghani-Mamaqani, Hossein [Department of Polymer Engineering, Sahand University of Technology, PO Box 51335-1996, Tabriz (Iran, Islamic Republic of)

    2014-11-15

    Graphical abstract: Effect of mesoporous silica nanoparticles (MCM-41) on the activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) is investigated. Decrement of conversion and number average molecular weight and also increment of polydispersity index (PDI) values are three main results of addition of MCM-41 nanoparticles. Incorporation of MCM-41 nanoparticles in the polystyrene matrix can clearly increase thermal stability and decrease glass transition temperature of the nanocomposites. - Highlights: • Spherical morphology, hexagonal structure, and high surface area with regular pore diameters of the synthesized MCM-41 nanoparticles are examined. • AGET ATRP of styrene in the presence of MCM-41 nanoparticles is performed. • Effect of MCM-41 nanoparticles addition on the polymerization rate, conversion and molecular weights of the products are discussed. • Improvement in thermal stability of the nanocomposites and decreasing T{sub g} values was also observed by incorporation of MCM-41 nanoparticles. - Abstract: Activator generated by electron transfer for atom transfer radical polymerization was employed to synthesize well-defined mesoporous silica nanoparticles/polystyrene composites. Inherent features of spherical mesoporous silica nanoparticles were evaluated by nitrogen adsorption/desorption isotherm, X-ray diffraction and scanning electron microscopy analysis techniques. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. By the addition of only 3 wt% mesoporous silica nanoparticles, conversion decreases from 81 to 58%. Similarly, number average molecular weight decreases from 17,116 to 12,798 g mol{sup −1}. However, polydispersity index (PDI) values increases from 1.24 to 1.58. A peak around 4.1–4.2 ppm at proton nuclear magnetic resonance spectroscopy results clearly confirms the living nature of the polymerization. Thermogravimetric

  4. Single-molecule Mapping of Long-range Electron Transfer for a Cytochrome b562 Variant

    DEFF Research Database (Denmark)

    Della Pia, Eduardo Antonio; Chi, Qijin; Jones, D. Dafydd

    2011-01-01

    Cytochrome b562 was engineered to introduce a cysteine residue at a surface-exposed position to facilitate direct self-assembly on a Au(111) surface. The confined protein exhibited reversible and fast electron exchange with a gold substrate over a distance of 20 Å between the heme redox center an...

  5. Chemical models of chains electron transfer in hydroxylating ferment systems

    International Nuclear Information System (INIS)

    Akhrem, A.A.; Kiselev, P.A.; Metelitsa, D.I.

    1977-01-01

    The rate constants are measured of consumption of nicotineamidedinucleotide (NAD-N) during its oxidation by molecular oxygen with the participation of Ti 4+ , Sn 4+ , Cu 2+ , Fe 3+ , VO 2+ , and Ce 4+ ions in mixtures of acetonitrile with water and of dioxane with water taken in a volume ratio of 1:1 (46 deg C). The kinetics of oxidation of NAD-N with the participation of Ti 4+ at 37 deg C in a water-acetonitrile medium is studied in detail. The hydroxylating capacity of the system NAD-N - Ti 4+ - O 2 with respect to naphthalene is proved. The reaction mechanism and its relationship with the microsomal chains of electron transport are discussed

  6. Modulating Pathways for Electron and Energy Transfer Through Molecules

    DEFF Research Database (Denmark)

    Pirrotta, Alessandro

    Energy transport efficiency and electric conductance are molecular properties that motivates the development of optoelectronic materials, energy storage, and electronic devices. Several experimental techniques allow measurement of these properties and regularly, modeling is employed to find...... correlations between chemical structure and molecular properties. This dissertation discusses the interplay between modeling and experiments toward the assessment of new relations between the molecular structure and properties. In particular, it has been shown how simulations can push the development of new...... experimental techniques, demonstrate the potential of already established techniques, and work in synergy with experiments. It is demonstrated how the use of modeling can expand our understanding of how chemical structure affects molecular properties, which will enable us to design molecules with specific...

  7. Reactivity of hydropersulfides toward the hydroxyl radical unraveled: disulfide bond cleavage, hydrogen atom transfer, and proton-coupled electron transfer.

    Science.gov (United States)

    Anglada, Josep M; Crehuet, Ramon; Adhikari, Sarju; Francisco, Joseph S; Xia, Yu

    2018-02-14

    Hydropersulfides (RSSH) are highly reactive as nucleophiles and hydrogen atom transfer reagents. These chemical properties are believed to be key for them to act as antioxidants in cells. The reaction involving the radical species and the disulfide bond (S-S) in RSSH, a known redox-active group, however, has been scarcely studied, resulting in an incomplete understanding of the chemical nature of RSSH. We have performed a high-level theoretical investigation on the reactions of the hydroxyl radical (˙OH) toward a set of RSSH (R = -H, -CH 3 , -NH 2 , -C(O)OH, -CN, and -NO 2 ). The results show that S-S cleavage and H-atom abstraction are the two competing channels. The electron inductive effect of R induces selective ˙OH substitution at one sulfur atom upon S-S cleavage, forming RSOH and ˙SH for the electron donating groups (EDGs), whereas producing HSOH and ˙SR for the electron withdrawing groups (EWGs). The H-Atom abstraction by ˙OH follows a classical hydrogen atom transfer (hat) mechanism, producing RSS˙ and H 2 O. Surprisingly, a proton-coupled electron transfer (pcet) process also occurs for R being an EDG. Although for RSSH having EWGs hat is the leading channel, S-S cleavage can be competitive or even dominant for the EDGs. The overall reactivity of RSSH toward ˙OH attack is greatly enhanced with the presence of an EDG, with CH 3 SSH being the most reactive species found in this study (overall rate constant: 4.55 × 10 12 M -1 s -1 ). Our results highlight the complexity in RSSH reaction chemistry, the extent of which is closely modulated by the inductive effect of the substituents in the case of the oxidation by hydroxyl radicals.

  8. The weak π − π interaction originated resonant tunneling and fast switching in the carbon based electronic devices

    Directory of Open Access Journals (Sweden)

    Jun He

    2012-03-01

    Full Text Available By means of the nonequilibrium Green's functions and the density functional theory, we have investigated the electronic transport properties of C60 based electronic device with different intermolecular interactions. It is found that the electronic transport properties vary with the types of the interaction between two C60 molecules. A fast electrical switching behavior based on negative differential resistance has been found when two molecules are coupled by the weak π − π interaction. Compared to the solid bonding, the weak interaction is found to induce resonant tunneling, which is responsible for the fast response to the applied electric field and hence the velocity of switching.

  9. Effect of prepulse on fast electron lateral transport at the target surface irradiated by intense femtosecond laser pulses

    International Nuclear Information System (INIS)

    Lin, X. X.; Li, Y. T.; Liu, B. C.; Liu, F.; Du, F.; Wang, S. J.; Lu, X.; Chen, L. M.; Zhang, L.; Liu, X.; Wang, J.; Liu, F.; Liu, X. L.; Wang, Z. H.; Ma, J. L.; Wei, Z. Y.; Zhang, J.

    2010-01-01

    The effects of preplasma on lateral fast electron transport at front target surface, irradiated by ultraintense (>10 18 W/cm 2 ) laser pulses, are investigated by Kα imaging technique. A large annular Kα halo with a diameter of ∼560 μm surrounding a central spot is observed. A specially designed steplike target is used to identify the possible mechanisms. It is believed that the halos are mainly generated by the lateral diffusion of fast electrons due to the electrostatic and magnetic fields in the preplasma. This is illustrated by simulated electron trajectories using a numerical model.

  10. Design and measurements of a fast high-voltage pulse generator for the MedAustron Low Energy Transfer line fast deflector

    CERN Document Server

    Fowler, T; Mueller, F; Kramer, T; Stadlbauer, T

    2012-01-01

    MedAustron, a centre for ion-therapy and research, will comprise an accelerator facility based on a synchrotron for the delivery of protons and light ions for cancer treatment. The Low Energy Beam Transfer line (LEBT) to the synchrotron contains an electrostatic fast deflector (EFE) which, when energized, deviates the continuous beam arriving from the ion source onto a Faraday Cup: the specified voltage is ±3.5 kV. De-energizing the EFE for variable pulse durations from 500 ns up to d.c. allows beam passage for multi-turn injection into the synchrotron. To maintain beam quality in the synchrotron, the EFE pulse generator requires rise and fall times of less than 300 ns between 90 % of peak voltage and a ±1 V level. To achieve this, a pulsed power supply (PKF), with high voltage MOSFET switches connected in a push-pull configuration, will be mounted in close proximity to the deflector itself. A fast, large dynamic range monitoring circuit will verify switching to the ±1 V level and subsequent flat bottom pu...

  11. Numerical study of the electron heating and current drive by the fast waves in the JFT-2M tokamak plasma

    International Nuclear Information System (INIS)

    Yamamoto, Takumi; Uesugi, Yoshihiko; Hoshino, Katsumichi; Kawashima, Hisato; Ohtsuka, Hideo

    1986-08-01

    A 200 MHz fast wave experiment for the JET-2M tokamak is examined. Noticeable single-path electron Landau damping of the fast waves with the parallel refractive index of N // = 4 is expected in the plasma with electron temperature more than 2.5 keV at the electron density of n e = 1.5 x 10 19 m -3 . Furthermore, it is shown that 8 kA of the plasma current is driven by the fast waves with N //≅ 2 at n e = 3 x 10 19 m -3 in the single-path damping when 100 kW of the rf power radiates into the plasma in the presence of the hot electrons with the temperature of 19 keV and the fraction of the density of 2 %. (author)

  12. Transfer function restoration in 3D electron microscopy via iterative data refinement

    International Nuclear Information System (INIS)

    Sorzano, C O S; Marabini, R; Herman, G T; Censor, Y; Carazo, J M

    2004-01-01

    Three-dimensional electron microscopy (3D-EM) is a powerful tool for visualizing complex biological systems. As with any other imaging device, the electron microscope introduces a transfer function (called in this field the contrast transfer function, CTF) into the image acquisition process that modulates the various frequencies of the signal. Thus, the 3D reconstructions performed with these CTF-affected projections are also affected by an implicit 3D transfer function. For high-resolution electron microscopy, the effect of the CTF is quite dramatic and limits severely the achievable resolution. In this work we make use of the iterative data refinement (IDR) technique to ameliorate the effect of the CTF. It is demonstrated that the approach can be successfully applied to noisy data

  13. Anion Photoelectron Spectroscopy of the Homogenous 2-Hydroxypyridine Dimer Electron Induced Proton Transfer System

    Science.gov (United States)

    Vlk, Alexandra; Stokes, Sarah; Wang, Yi; Hicks, Zachary; Zhang, Xinxing; Blando, Nicolas; Frock, Andrew; Marquez, Sara; Bowen, Kit; Bowen Lab JHU Team

    Anion photoelectron spectroscopic (PES) and density functional theory (DFT) studies on the dimer anion of (2-hydroxypyridine)2-are reported. The experimentally measured vertical detachment energy (VDE) of 1.21eV compares well with the theoretically predicted values. The 2-hydroxypyridine anionic dimer system was investigated because of its resemblance to the nitrogenous heterocyclic pyrimidine nucleobases. Experimental and theoretical results show electron induced proton transfer (EIPT) in both the lactim and lactam homogeneous dimers. Upon electron attachment, the anion can serve as the intermediate between the two neutral dimers. A possible double proton transfer process can occur from the neutral (2-hydroxypyridine)2 to (2-pyridone)2 through the dimer anion. This potentially suggests an electron catalyzed double proton transfer mechanism of tautomerization. Research supported by the NSF Grant No. CHE-1360692.

  14. Three-dimensional optical transfer functions in the aberration-corrected scanning transmission electron microscope.

    Science.gov (United States)

    Jones, L; Nellist, P D

    2014-05-01

    In the scanning transmission electron microscope, hardware aberration correctors can now correct for the positive spherical aberration of round electron lenses. These correctors make use of nonround optics such as hexapoles or octupoles, leading to the limiting aberrations often being of a nonround type. Here we explore the effect of a number of potential limiting aberrations on the imaging performance of the scanning transmission electron microscope through their resulting optical transfer functions. In particular, the response of the optical transfer function to changes in defocus are examined, given that this is the final aberration to be tuned just before image acquisition. The resulting three-dimensional optical transfer functions also allow an assessment of the performance of a system for focal-series experiments or optical sectioning applications. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

  15. Nobel Prize 1992: Rudolph A. Marcus: theory of electron transfer reactions in chemical systems

    International Nuclear Information System (INIS)

    Ulate Segura, Diego Guillermo

    2011-01-01

    A review of the theory developed by Rudolph A. Marcus is presented, who for his rating to the theory of electron transfer in chemical systems was awarded the Nobel Prize in Chemistry in 1992. Marcus theory has constituted not only a good extension of the use of a spectroscopic principle, but also has provided an energy balance and the application of energy conservation for electron transfer reactions. A better understanding of the reaction coordinate is exposed in terms energetic and establishing the principles that govern the transfer of electrons, protons and some labile small molecular groups as studied at present. Also, the postulates and equations described have established predictive models of reaction time, very useful for industrial environments, biological, metabolic, and others that involve redox processes. Marcus theory itself has also constituted a large contribution to the theory of complex transition [es

  16. Technology transfer present and futures in the electronic arts

    Directory of Open Access Journals (Sweden)

    Brian Degger

    2008-01-01

    Full Text Available We are entering an era where creating the fantastical is possible in the arts. In the areas of mixed reality and biological arts, responsive works are created based on advances in basic science and technology. This is enabling scientists and artists to pose new questions. As the time between discovery and application is so short, artists need imaginative ways of accessing new technology in order to critique and use it.These are the new paints that the majority of artists cannot afford or access, technology to enable cloning of DNA, to print channels on a chip, to access proprietary 3G networks. Currently, partnerships or residencies are used to facilitate artist’s access to these technologies. What would they do if technology was available that enabled them to make any art work they so desire? Are the limitations in current technology an advantage rather than a disadvantage in some of their works? Does interaction with technologists make their work more robust? Are there disadvantages? How do they get access to the technology they require? Open source or proprietary? Or have they encountered the situation where their vision is greater than technology allows. When their work breaks because of this fact, is their art broken? Blast Theory (Brighton,UK, FoAM(Brussels, Belgium and Amsterdam, Netherlands, SymbioticA (Perth, Australia are organisations pushing technological boundaries in the service of art. This paper addresses some questions of technology transfer in relation to recent artworks, particularly I like Frank in Adelaide (Blast Theory, transient reality generators (trg (FoAM and Multi electrode array artist (MeART (SymbioticA.

  17. DFT and time-resolved IR investigation of electron transfer between photogenerated 17- and 19-electron organometallic radicals

    Energy Technology Data Exchange (ETDEWEB)

    Cahoon, James B.; Kling, Matthias F.; Sawyer, Karma R.; Andersen, Lars K.; Harris, Charles B.

    2008-04-30

    The photochemical disproportionation mechanism of [CpW(CO){sub 3}]{sub 2} in the presence of Lewis bases PR{sub 3} was investigated on the nano- and microsecond time-scales with Step-Scan FTIR time-resolved infrared spectroscopy. 532 nm laser excitation was used to homolytically cleave the W-W bond, forming the 17-electron radicals CpW(CO){sub 3} and initiating the reaction. With the Lewis base PPh{sub 3}, disproportionation to form the ionic products CpW(CO){sub 3}PPh{sub 3}{sup +} and CpW(CO){sub 3}{sup -} was directly monitored on the microsecond time-scale. Detailed examination of the kinetics and concentration dependence of this reaction indicates that disproportionation proceeds by electron transfer from the 19-electron species CpW(CO){sub 3}PPh{sub 3} to the 17-electron species CpW(CO){sub 3}. This result is contrary to the currently accepted disproportionation mechanism which predicts electron transfer from the 19-electron species to the dimer [CpW(CO){sub 3}]{sub 2}. With the Lewis base P(OMe){sub 3} on the other hand, ligand substitution to form the product [CpW(CO){sub 2}P(OMe){sub 3}]{sub 2} is the primary reaction on the microsecond time-scale. Density Functional Theory (DFT) calculations support the experimental results and suggest that the differences in the reactivity between P(OMe){sub 3} and PPh{sub 3} are due to steric effects. The results indicate that radical-to-radical electron transfer is a previously unknown but important process for the formation of ionic products with the organometallic dimer [CpW(CO){sub 3}]{sub 2} and may also be applicable to the entire class of organometallic dimers containing a single metal-metal bond.

  18. Automation of Sample Transfer and Counting on Fast Neutron ActivationSystem

    International Nuclear Information System (INIS)

    Dewita; Budi-Santoso; Darsono

    2000-01-01

    The automation of sample transfer and counting were the transfer processof the sample to the activation and counting place which have been done byswitch (manually) previously, than being developed by automaticallyprogrammed logic instructions. The development was done by constructed theelectronics hardware and software for that communication. Transfer timemeasurement is on seconds and was done automatically with an error 1.6 ms.The counting and activation time were decided by the user on seconds andminutes, the execution error on minutes was 8.2 ms. This development systemwill be possible for measuring short half live elements and cyclic activationprocesses. (author)

  19. Electron transfer across anodic films formed on tin in carbonate-bicarbonate buffer solution

    International Nuclear Information System (INIS)

    Gervasi, C.A.; Folquer, M.E.; Vallejo, A.E.; Alvarez, P.E.

    2005-01-01

    Impedance and steady-state data were recorded in order to study the kinetics of electron transfer between passive tin electrodes and an electrolytic solution containing the K 3 Fe(CN) 6 -K 4 Fe(CN) 6 redox couple. Film thickness plays a key role in determining the type of electronic conduction of these oxide covered electrodes. Electron exchange with the oxide takes place with participation of the conduction band in the semiconducting film. A mechanism involving direct electron tunneling through the space charge barrier is the most suitable to interpret the experimental evidence

  20. Electron transfer across anodic films formed on tin in carbonate-bicarbonate buffer solution

    Energy Technology Data Exchange (ETDEWEB)

    Gervasi, C.A. [Universidad Nacional de La Plata (Argentina). Facultad de Ciencias Exactas; Universidad Nacional de La Plata (Argentina). Facultad de Ingenieria; Folquer, M.E. [Universidad Nacional de Tucaman (Argentina). Inst. de Quimica Fisica; Vallejo, A.E. [Universidad Nacional de La Plata (Argentina). Facultad de Ingenieria; Alvarez, P.E. [Universidad Nacional de Tucaman (Argentina). Inst. de Fisica

    2005-01-15

    Impedance and steady-state data were recorded in order to study the kinetics of electron transfer between passive tin electrodes and an electrolytic solution containing the K{sub 3}Fe(CN){sub 6}-K{sub 4}Fe(CN){sub 6} redox couple. Film thickness plays a key role in determining the type of electronic conduction of these oxide covered electrodes. Electron exchange with the oxide takes place with participation of the conduction band in the semiconducting film. A mechanism involving direct electron tunneling through the space charge barrier is the most suitable to interpret the experimental evidence. (Author)

  1. Electron-transfer reactions of extremely small AgI colloids

    International Nuclear Information System (INIS)

    Vucemilovic, M.I.; Micic, O.I.

    1988-01-01

    Small colloidal AgI particles (particle diameter 20-50 A) have been prepared in water and acetonitrile, and optical effects due to size quantization have been observed. Electron transfer reactions involving electron donors and electron acceptors with AgI have been studied by pulse radiolysis techniques. Both reduction and oxidation of the colloids led to transient bleaching of semiconductor absorption. The recovery of the bleaching has been attributed to corrosion processes. Electrons injected into AgI colloids produce metallic silver and hydrogen. Hydrogen evolution is catalyzed by metallic silver formation. (author)

  2. Fe electron transfer and atom exchange in goethite: influence of Al-substitution and anion sorption.

    Science.gov (United States)

    Latta, Drew E; Bachman, Jonathan E; Scherer, Michelle M

    2012-10-02

    The reaction of Fe(II) with Fe(III) oxides and hydroxides is complex and includes sorption of Fe(II) to the oxide, electron transfer between sorbed Fe(II) and structural Fe(III), reductive dissolution coupled to Fe atom exchange, and, in some cases mineral phase transformation. Much of the work investigating electron transfer and atom exchange between aqueous Fe(II) and Fe(III) oxides has been done under relatively simple aqueous conditions in organic buffers to control pH and background electrolytes to control ionic strength. Here, we investigate whether electron transfer is influenced by cation substitution of Al(III) in goethite and the presence of anions such as phosphate, carbonate, silicate, and natural organic matter. Results from (57)Fe Mössbauer spectroscopy indicate that both Al-substitution (up to 9%) and the presence of common anions (PO(4)(3-), CO(3)(2-), SiO(4)(4-), and humic acid) does not inhibit electron transfer between aqueous Fe(II) and Fe(III) in goethite under the conditions we studied. In contrast, sorption of a long-chain phospholipid completely shuts down electron transfer. Using an enriched isotope tracer method, we found that Al-substitution in goethite (10%), does, however, significantly decrease the extent of atom exchange between Fe(II) and goethite (from 43 to 12%) over a month's time. Phosphate, somewhat surprisingly, appears to have little effect on the rate and extent of atom exchange between aqueous Fe(II) and goethite. Our results show that electron transfer between aqueous Fe(II) and solid Fe(III) in goethite can occur under wide range of geochemical conditions, but that the extent of redox-driven Fe atom exchange may be dependent on the presence of substituting cations such as Al.

  3. Promotion of multi-electron transfer for enhanced photocatalysis: A review focused on oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Changhua [Centre for Advanced Optoelectronic Functional Materials Research, and Key Laboratory for UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024 (China); College of Chemistry and Biology, Beihua University, Jilin 132013 (China); Zhang, Xintong, E-mail: xtzhang@nenu.edu.cn [Centre for Advanced Optoelectronic Functional Materials Research, and Key Laboratory for UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024 (China); Liu, Yichun [Centre for Advanced Optoelectronic Functional Materials Research, and Key Laboratory for UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024 (China)

    2015-12-15

    Highlights: • Oxygen reduction reaction (ORR) in photocatalysis process is focused. • Multi-electron transfer ORR is reviewed. • This review provides a guide to access to enhanced photocatalysis via multi-electron transfer. - Abstract: Semiconductor photocatalysis has attracted significant interest for solar light induced environmental remediation and solar fuel generation. As is well known, photocatalytic performance is determined by three steps: photoexcitation, separation and transport of photogenerated charge carriers, and surface reactions. To achieve higher efficiency, significant efforts have been made on improvement of efficiency of above first two steps, which have been well documented in recent review articles. In contrast, this review intends to focus on strategies moving onto the third step of improvement for enhanced photocatalysis wherein active oxygen species including superoxide radical, hydrogen peroxide, hydroxyl radical are in situ detected. Particularly, surface electron-transfer reduction of oxygen over single component photocatalysts is reviewed and systems enabling multi-electron transfer induced oxygen reduction reaction (ORR) are highlighted. It is expected this review could provide a guideline for readers to better understand the critical role of ORR over photocatalyst in charge carrier separation and transfer and obtain reliable results for enhanced aerobic photocatalysis.

  4. A fast radiative transfer model for visible through shortwave infrared spectral reflectances in clear and cloudy atmospheres

    International Nuclear Information System (INIS)

    Wang, Chenxi; Yang, Ping; Nasiri, Shaima L.; Platnick, Steven; Baum, Bryan A.; Heidinger, Andrew K.; Liu, Xu

    2013-01-01

    A computationally efficient radiative transfer model (RTM) for calculating visible (VIS) through shortwave infrared (SWIR) reflectances is developed for use in satellite and airborne cloud property retrievals. The full radiative transfer equation (RTE) for combinations of cloud, aerosol, and molecular layers is solved approximately by using six independent RTEs that assume the plane-parallel approximation along with a single-scattering approximation for Rayleigh scattering. Each of the six RTEs can be solved analytically if the bidirectional reflectance/transmittance distribution functions (BRDF/BTDF) of the cloud/aerosol layers are known. The adding/doubling (AD) algorithm is employed to account for overlapped cloud/aerosol layers and non-Lambertian surfaces. Two approaches are used to mitigate the significant computational burden of the AD algorithm. First, the BRDF and BTDF of single cloud/aerosol layers are pre-computed using the discrete ordinates radiative transfer program (DISORT) implemented with 128 streams, and second, the required integral in the AD algorithm is numerically implemented on a twisted icosahedral mesh. A concise surface BRDF simulator associated with the MODIS land surface product (MCD43) is merged into a fast RTM to accurately account for non-isotropic surface reflectance. The resulting fast RTM is evaluated with respect to its computational accuracy and efficiency. The simulation bias between DISORT and the fast RTM is large (e.g., relative error >5%) only when both the solar zenith angle (SZA) and the viewing zenith angle (VZA) are large (i.e., SZA>45° and VZA>70°). For general situations, i.e., cloud/aerosol layers above a non-Lambertian surface, the fast RTM calculation rate is faster than that of the 128-stream DISORT by approximately two orders of magnitude. -- Highlights: ► An efficient radiative transfer model is developed for cloud remote sensing. ► Multi-layered clouds and a non-Lambertian surface can be fully considered.

  5. Studies of transfer reactions of photosensitized electrons involving complexes of transition metals in view of solar energy storage

    International Nuclear Information System (INIS)

    Takakubo, Masaaki

    1984-01-01

    This research thesis addresses electron transfer reactions occurring during photosynthesis, for example, photosensitized reaction in which chlorophyll is the sensitizer. More specifically, the author studied experimentally electron photo-transfers with type D sensitizers (riboflavin, phenoxazine and porphyrin), and various complexes of transition metals. After a presentation of these experiments, the author describes the photosensitisation process (photo-physics of riboflavin, oxygen deactivation, sensitized photo-oxidation and photo-reduction). The theoretical aspect of electron transfer is then addressed: generalities, deactivation of the riboflavin triplet, initial efficiency of electron transfer. Experimental results on three basic processes (non-radiative deactivation, energy transfer, electron transfer) are interpreted in a unified way by using the non-radiative transfer theory. Some applications are described: photo-electrochemical batteries, photo-oxidation and photo-reduction of the cobalt ion

  6. A structural basis for electron transfer in bacterial photosynthesis

    International Nuclear Information System (INIS)

    Norris, J.R.; DiMagno, T.J.; Angerhofer, A.; Chang, C.H.; El-Kabbani, O.; Schiffer, M.

    1989-01-01

    Triplet data for the primary donor in single crystals of bacterial reaction centers of Rhodobacter sphaeroides and Rhodopseudomonas viridis are interpreted in terms of the corresponding x-ray structures. The analysis of electron paramagnetic resonance data from single crystals (triplet zero field splitting and cation and triplet linewidth of the primary special pair donor of bacterial reaction centers) is extended to systems of a non-crystalline nature. A unified interpretation based on frontier molecular orbitals concludes that the special pair behaves like a supermolecule in all wild-type bacteria investigated here. However, in heterodimers of Rb. capsulatus (His M200 changed to Leu or Phe with the result that the M-half of the special pair is converted to bacteriopheophytin) the special pair possesses the EPR properties more appropriately described in terms of a monomer. In all cases the triplet state and cation EPR properties appear to be dominated by the highest occupied molecular orbitals. These conclusions derived from EPR experiments are supplemented by data from Stark spectroscopy of reaction centers from Rb. capsulatus. 41 refs., 3 tabs

  7. Photo-induced regeneration of hormones by electron transfer processes: Potential biological and medical consequences

    Science.gov (United States)

    Getoff, Nikola; Hartmann, Johannes; Schittl, Heike; Gerschpacher, Marion; Quint, Ruth Maria

    2011-08-01

    Based on the previous results concerning electron transfer processes in biological substances, it was of interest to investigate if hormone transients resulting by e.g. electron emission can be regenerated. The presented results prove for the first time that the hormone transients originating by the electron emission process can be successfully regenerated by the transfer of electrons from a potent electron donor, such as vitamin C (VitC). Investigations were performed using progesterone (PRG), testosterone (TES) and estrone (E1) as representatives of hormones. By irradiation with monochromatic UV light (λ=254 nm) in a media of 40% water and 60% ethanol, the degradation as well as the regeneration of the hormones was studied with each hormone individually and in the mixture with VitC as a function of the absorbed UV dose, using HPLC. Calculated from the obtained initial yields, the determined regeneration of PRG amounted to 52.7%, for TES to 58.6% and for E1 to 90.9%. The consumption of VitC was determined in the same way. The reported results concerning the regeneration of hormones by the transfer of electrons from an electron donor offer a new, promising method for the therapy with hormones. As a consequence of the regeneration of hormones, a decreased formation of carcinogenic metabolites is expected.

  8. Photo-induced regeneration of hormones by electron transfer processes: Potential biological and medical consequences

    Energy Technology Data Exchange (ETDEWEB)

    Getoff, Nikola, E-mail: nikola.getoff@univie.ac.a [Section of Radiation Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna (Austria); Hartmann, Johannes [Department of Gynecologic Endocrinology and Reproduction, Medical University of Vienna, A-1090 Vienna (Austria); Schittl, Heike [Section of Radiation Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna (Austria); Gerschpacher, Marion [Department of Gynecologic Endocrinology and Reproduction, Medical University of Vienna, A-1090 Vienna (Austria); Quint, Ruth Maria [Section of Radiation Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna (Austria)

    2011-08-15

    Based on the previous results concerning electron transfer processes in biological substances, it was of interest to investigate if hormone transients resulting by e.g. electron emission can be regenerated. The presented results prove for the first time that the hormone transients originating by the electron emission process can be successfully regenerated by the transfer of electrons from a potent electron donor, such as vitamin C (VitC). Investigations were performed using progesterone (PRG), testosterone (TES) and estrone (E1) as representatives of hormones. By irradiation with monochromatic UV light ({lambda}=254 nm) in a media of 40% water and 60% ethanol, the degradation as well as the regeneration of the hormones was studied with each hormone individually and in the mixture with VitC as a function of the absorbed UV dose, using HPLC. Calculated from the obtained initial yields, the determined regeneration of PRG amounted to 52.7%, for TES to 58.6% and for E1 to 90.9%. The consumption of VitC was determined in the same way. The reported results concerning the regeneration of hormones by the transfer of electrons from an electron donor offer a new, promising method for the therapy with hormones. As a consequence of the regeneration of hormones, a decreased formation of carcinogenic metabolites is expected.

  9. Photo-induced regeneration of hormones by electron transfer processes: Potential biological and medical consequences

    International Nuclear Information System (INIS)

    Getoff, Nikola; Hartmann, Johannes; Schittl, Heike; Gerschpacher, Marion; Quint, Ruth Maria

    2011-01-01

    Based on the previous results concerning electron transfer processes in biological substances, it was of interest to investigate if hormone transients resulting by e.g. electron emission can be regenerated. The presented results prove for the first time that the hormone transients originating by the electron emission process can be successfully regenerated by the transfer of electrons from a potent electron donor, such as vitamin C (VitC). Investigations were performed using progesterone (PRG), testosterone (TES) and estrone (E1) as representatives of hormones. By irradiation with monochromatic UV light (λ=254 nm) in a media of 40% water and 60% ethanol, the degradation as well as the regeneration of the hormones was studied with each hormone individually and in the mixture with VitC as a function of the absorbed UV dose, using HPLC. Calculated from the obtained initial yields, the determined regeneration of PRG amounted to 52.7%, for TES to 58.6% and for E1 to 90.9%. The consumption of VitC was determined in the same way. The reported results concerning the regeneration of hormones by the transfer of electrons from an electron donor offer a new, promising method for the therapy with hormones. As a consequence of the regeneration of hormones, a decreased formation of carcinogenic metabolites is expected.

  10. Radiation heat transfer through the gas of a sodium cooled fast breeder reactor

    International Nuclear Information System (INIS)

    Pradel, P.; Frachet, S.; Petit, D.

    1984-04-01

    Analysis based on results from the COCA test campaign and Germinal mockup of Super Phenix upper shuttings, of the heat transfers and radiation attenuation due to sodium aerosols between the free surface of sodium and the upper shuttings

  11. Direct electron transfer: an approach for electrochemical biosensors with higher selectivity and sensitivity

    Directory of Open Access Journals (Sweden)

    Freire Renato S.

    2003-01-01

    Full Text Available The most promising approach for the development of electrochemical biosensors is to establish a direct electrical communication between the biomolecules and the electrode surface. This review focuses on advances, directions and strategies in the development of third generation electrochemical biosensors. Subjects covered include a brief description of the fundamentals of the electron transfer phenomenon and amperometric biosensor development (different types and new oriented enzyme immobilization techniques. Special attention is given to different redox enzymes and proteins capable of electrocatalyzing reactions via direct electron transfer. The analytical applications and future trends for third generation biosensors are also presented and discussed.

  12. Intramolecular electron transfer in ascorbate oxidase is enhanced in the presence of oxygen

    DEFF Research Database (Denmark)

    Farver, O; Wherland, S; Pecht, I

    1994-01-01

    Intramolecular electron transfer from the type 1 copper center to the type 3 copper(II) pair is induced in the multi-copper enzyme, ascorbate oxidase, following pulse radiolytic reduction of the type 1 Cu(II) ion. In the presence of a slight excess of dioxygen over ascorbate oxidase, interaction...... between the trinuclear copper center and O2 is observed even with singly reduced ascorbate oxidase molecules. Under these conditions, the rate constant for intramolecular electron transfer from type 1 Cu(I) to type 3 Cu(II) increases 5-fold to 1100 +/- 300 s-1 (20 degrees C, pH 5.8) as compared...

  13. Deuterium isotope effect on the intramolecular electron transfer in Pseudomonas aeruginosa azurin

    DEFF Research Database (Denmark)

    Farver, O.; Zhang, Jingdong; Chi, Qijin

    2001-01-01

    rather than negative. Isotope effects are, however, also inherent in the nuclear reorganization Gibbs free energy and in the tunneling factor for the electron transfer process. A slightly larger thermal protein expansion in H2O than in D2O (0.001 nm K-1) is sufficient both to account for the activation......Intramolecular electron transfer in azurin in water and deuterium oxide has been studied over a broad temperature range. The kinetic deuterium isotope effect, k(H)/k(D), is smaller than unity (0.7 at 298 K), primarily caused by the different activation entropies in water (-56.5 J K-1 mol(-1...

  14. Electron transfer and photophosphorylation in mitochondria of buckwheat after irradiation of seeds with. gamma. -rays

    Energy Technology Data Exchange (ETDEWEB)

    Guseva, V A; Kurganova, L N; Gorlanova, T M [Gor' kovskij Gosudarstvennyj Univ. (USSR)

    1974-11-01

    Pre-sowing irradiation of seeds at 500 R activates the transfer of electrons by photosynthetic electron transfer path of isolated buchwheat chloroplasts in the ontogenesis and stimulates the conjugated photosynthetic phosphorilation. An increased content of NADPxH/sub 2/ is observed along with an elevated level of ATP production. Intensification of oxidative phosphorilation and growth of the P/O ratio of mitochondria has been shown in the ''irradiated'' plants, together with a concomitant increase of ATPhase activity in chloroplasts and mitochondria.

  15. Features of the mass transfer in magnetic cataclysmic variables with fast-rotating white dwarfs

    Directory of Open Access Journals (Sweden)

    Isakova Polina

    2014-01-01

    Full Text Available The flow structure in magnetic cataclysmic variables was investigated taking into account the effects of strong magnetic field and fast rotation of the white dwarf. We modeled the AE Aqr system as a unique object that has the rotation period of the white dwarf is about 1000 times shorter than the orbital period of the binary system. Observations show that in spite of fast rotation of the white dwarf some part of the stream from the inner Lagrange point comes into the Roche lobe region. We analyzed possible mechanisms preventing material to outflow from the system.

  16. Effects of fast monoenergetic electrons on the ion dynamics near the cathode in a pulsed direct current plasma sheath

    International Nuclear Information System (INIS)

    Sharifian, M.; Shokri, B.

    2008-01-01

    A detailed one-dimensional simulation of the ion dynamics of the plasma sheath near a substrate (cathode) in the presence of fast monoenergetic electrons has been carried out in this article. The sheath evolution is investigated by using a fluid model assuming that the ions, plasma electrons and monoenergetic, fast electrons act as three fluids (fluid approach). The effect of the density of fast electrons on the ion density, ion velocity, and ion energy near the cathode and the evolution of the sheath boundary in front of the cathode are separately explored. Also, the variation of the ion velocity and ion density at the vicinity of the cathode as a function of time is investigated in the absence and presence of the electron beam. Results indicate that the presence of fast electrons in the sheath causes significant change in the sheath thickness and therefore basically changes the ion velocity, ion density, and ion impact energy on the cathode compared to the absence of the electron beam case

  17. Evidence for fast-electron-driven Alfvenic modes in the HSX stellarator

    International Nuclear Information System (INIS)

    Brower, D.L.; Deng, C.; Spong, D.A.; Abdou, A.; Almagri, A.F.; Anderson, D.T.; Anderson, F.S.B.; Guttenfelder, W.; Likin, K.; Oh, S.; Sakaguchi, V.; Talmadge, J.N.; Zhai, K.

    2005-01-01

    The helically-symmetric experiment (HSX) stellarator device is the first of a new generation of stellarators that exploit the concept of quasi-symmetric magnetic fields. In HSX, the plasma is both produced and heated by use of electron cyclotron resonance heating (ECRH) at the 2nd harmonic X-mode resonance. This heating configuration generates a nonthermal energetic electron population. Herein, we report on the first experimental evidence for fast-electron-driven Global Alfven Eigenmodes (GAE). This mode has previously been observed in both tokamaks and stellarators but it was always driven by energetic ions, not electrons. Evidence for this instability is obtained from quasi-helically symmetric HSX plasmas. Potential consequences of these measurements are twofold; (1) fast electrons can drive the GAE instability, and (2) quasi-symmetry makes a difference by better confining the particles that drive the instability as compared to the conventional stellarator configuration. We report on several features of this fluctuation. It is a coherent mode that is experimentally observed in the plasma core and edge by external magnetic coils, interferometry, ECE and Langmuir probes diagnostics. Fluctuations are observed in the frequency range of 20-120 kHz and scale with ion mass density according to expectations for Alfvenic modes. The mode is observed to be global with odd poloidal mode number (inferred from interferometry, possibly m=1) and is present in quasi-helically symmetric HSX plasmas. When quasi-helical symmetry is broken, the mode is no longer observed. Theory predicts a GAE mode in the gap below the Alfven continua can be excited in the frequency range of the measured fluctuations. By employing a biased electrode inserted deep into the plasma, flows can be generated. Under these conditions, the Alfvenic mode amplitude can increase and the fluctuation is even observed in the conventional stellarator configuration. Shifts in the measured frequency can be used to

  18. Tuning of Hemes b Equilibrium Redox Potential Is Not Required for Cross-Membrane Electron Transfer.

    Science.gov (United States)

    Pintscher, Sebastian; Kuleta, Patryk; Cieluch, Ewelina; Borek, Arkadiusz; Sarewicz, Marcin; Osyczka, Artur

    2016-03-25

    In biological energy conversion, cross-membrane electron transfer often involves an assembly of two hemesb The hemes display a large difference in redox midpoint potentials (ΔEm_b), which in several proteins is assumed to facilitate cross-membrane electron transfer and overcome a barrier of membrane potential. Here we challenge this assumption reporting on hemebligand mutants of cytochromebc1in which, for the first time in transmembrane cytochrome, one natural histidine has been replaced by lysine without loss of the native low spin type of heme iron. With these mutants we show that ΔEm_b can be markedly increased, and the redox potential of one of the hemes can stay above the level of quinone pool, or ΔEm_b can be markedly decreased to the point that two hemes are almost isopotential, yet the enzyme retains catalytically competent electron transfer between quinone binding sites and remains functionalin vivo This reveals that cytochromebc1can accommodate large changes in ΔEm_b without hampering catalysis, as long as these changes do not impose overly endergonic steps on downhill electron transfer from substrate to product. We propose that hemesbin this cytochrome and in other membranous cytochromesbact as electronic connectors for the catalytic sites with no fine tuning in ΔEm_b required for efficient cross-membrane electron transfer. We link this concept with a natural flexibility in occurrence of several thermodynamic configurations of the direction of electron flow and the direction of the gradient of potential in relation to the vector of the electric membrane potential. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Nitric Oxide Synthases Reveal a Role for Calmodulin in Controlling Electron Transfer

    Science.gov (United States)

    Abu-Soud, Husam M.; Stuehr, Dennis J.

    1993-11-01

    Nitric oxide (NO) is synthesized within the immune, vascular, and nervous systems, where it acts as a wide-ranging mediator of mammalian physiology. The NO synthases (EC 1.14.13.39) isolated from neurons or endothelium are calmodulin dependent. Calmodulin binds reversibly to neuronal NO synthase in response to elevated Ca2+, triggering its NO production by an unknown mechanism. Here we show that calmodulin binding allows NADPH-derived electrons to pass onto the heme group of neuronal NO synthase. Calmodulin-triggered electron transfer to heme was independent of substrate binding, caused rapid enzymatic oxidation of NADPH in the presence of O_2, and was required for NO synthesis. An NO synthase isolated from cytokine-induced macrophages that contains tightly bound calmodulin catalyzed spontaneous electron transfer to its heme, consistent with bound calmodulin also enabling electron transfer within this isoform. Together, these results provide a basis for how calmodulin may regulate NO synthesis. The ability of calmodulin to trigger electron transfer within an enzyme is unexpected and represents an additional function for calcium-binding proteins in biology.

  20. Development and testing of a fast digital electronic system for ion identification and spectroscopy

    International Nuclear Information System (INIS)

    Legou, Th.

    2002-02-01

    This report deals with a fast digital electronic system developed for ion identification and spectroscopy. The system, called IRIS, has been conceived for the super heavy element research program: FUSION. In order to observe a super heavy element, the energy of the compound nucleus implanted in a silicon detector must be measured, and the alpha decay also registered. The associated electronics must therefore handle a very wide range of energies and also exhibit a small recovery time after the implantation of the compound nucleus. IRIS is connected to the output of a charge preamplifier. It digitizes the signal and then executes two digital signal processes: the first to detect the particle, and the second to determine the energy deposited in the silicon detector. The use of programmed processing allows for the adjustment of the digital processing parameters, as well as a choice of other digital signal processing procedures, depending the application. After having explained why a conventional electronic system cannot be used for the detection of super-heavy ions, IRIS' structure is detailed and a number of digital signal processing procedures are studied and tested. (author)