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

Optical model theory of elastic electron- and positron-atom scattering at intermediate energies

International Nuclear Information System (INIS)

Joachain, C.J.

1977-01-01

It is stated that the basic idea of the optical model theory is to enable analysis of the elastic scattering of a particle from a complex target by replacing the complicated interactions between the beam and the target by an optical potential, or pseudopotential, in which the incident particle moves. Once the optical potential is determined the original many-body elastic scattering problem reduces to a one-body situation. The resulting optical potential is, however, a very complicated operator, and the formal expressions obtained from first principles for the optical potential can only be evaluated approximately in a few simple cases, such as high energy elastic hadron-nucleus scattering, for the the optical potential can be expressed in terms of two-body hadron-nucleon amplitudes, and the non-relativistic elastic scattering of fast charged particles by atoms. The elastic scattering of an electron or positron by a neutral atom at intermediate energies is here considered. Exchange effects between the projectile and the atomic electrons are considered; also absorption and polarisation effects. Applications of the full-wave optical model have so far only been made to the elastic scattering of fast electrons and positrons by atomic H, He, Ne, and Ar. Agreements of the optical model results with absolute measurements of differential cross sections for electron scattering are very good, an agreement that improves as the energy increases, but deteriorates quickly as the incident energy becomes lower than 50 eV for atomic H or 100 eV for He. For more complex atoms the optical model calculations also appear very encouraging. With regard to positron-atom elastic scattering the optical model results for positron-He scattering differ markedly at small angles from the corresponding electron-He values. It would be interesting to have experimental angular distributions of positron-atom elastic scattering in order to check predictions of the optical model theory. (U.K.)

Excitation of vibrational quanta in furfural by intermediate-energy electrons

Science.gov (United States)

Jones, D. B.; Neves, R. F. C.; Lopes, M. C. A.; da Costa, R. F.; Varella, M. T. do N.; Bettega, M. H. F.; Lima, M. A. P.; García, G.; Blanco, F.; Brunger, M. J.

2015-12-01

We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°-90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule.

Excitation of vibrational quanta in furfural by intermediate-energy electrons

Energy Technology Data Exchange (ETDEWEB)

Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Neves, R. F. C. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Instituto Federal do Sul de Minas Gerais, Campus Poços de Caldas, Minas Gerais (Brazil); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, MG (Brazil); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, MG (Brazil); Costa, R. F. da [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, 09210-580 São Paulo (Brazil); Varella, M. T. do N. [Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); Lima, M. A. P. [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); and others

2015-12-14

We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°–90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule.

Excitation of vibrational quanta in furfural by intermediate-energy electrons

International Nuclear Information System (INIS)

Jones, D. B.; Neves, R. F. C.; Lopes, M. C. A.; Costa, R. F. da; Varella, M. T. do N.; Bettega, M. H. F.; Lima, M. A. P.; García, G.

2015-01-01

We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°–90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule

The electron-electron instability in a spherical plasma structure with an intermediate double layer

International Nuclear Information System (INIS)

Lapuerta, V.; Ahedo, E.

2003-01-01

A linear dynamic model of a spherical plasma structure with an intermediate double layer is analyzed in the high-frequency range. The two ion populations tend to stay frozen in their stationary response and this prevents the displacement of the double layer. Different electron modes dominate the plasma dynamics in each quasineutral region. The electrostatic potential and the electron current are the magnitudes most perturbed. The structure develops a reactive electron-electron instability, which is made up of a countable family of eigenmodes. Space-charge effects must be included in the quasineutral regions to determine the eigenmode carrying the maximum growth rate. Except for very small Debye lengths, the fundamental eigenmode governs the instability. The growth rate for the higher harmonics approaches that of an infinite plasma. The instability modes develop mainly on the plasma at the high-potential side of the double layer. The influence of the parameters defining the stationary solution on the instability growth rate is investigated, and the parametric regions of stability are found. The comparison with a couple of experiments on plasma contactors is satisfactory

On selection rules and inelastic electron scattering at intermediate energies

International Nuclear Information System (INIS)

Nuroh, K.

1986-12-01

Correlation effects are included in the Bethe-Born theory for the generalized oscillator strength of inelastic scattering of electrons on atoms. The formulation is such as to allow for the calculation of relative line strengths of multiplets. It is used to analyze line strengths of the 4d → 4f transition in La 3+ and Ce 4+ within LS-coupling. The analysis indicates that only singlet states of the intermediate 4d 9 4f configuration are allowed. Calculated line strengths are compared with a recent core electron energy loss spectra of metallic La and tetravalent CeO 2 and there is an overall qualitative agreement between theory and experiment. (author). 11 refs, 4 figs, 2 tabs

Communication: satisfying fermionic statistics in the modeling of open time-dependent quantum systems with one-electron reduced density matrices.

Science.gov (United States)

Head-Marsden, Kade; Mazziotti, David A

2015-02-07

For an open, time-dependent quantum system, Lindblad derived the most general modification of the quantum Liouville equation in the Markovian approximation that models environmental effects while preserving the non-negativity of the system's density matrix. While Lindblad's modification is correct for N-electron density matrices, solution of the Liouville equation with a Lindblad operator causes the one-electron reduced density matrix (1-RDM) to violate the Pauli exclusion principle. Consequently, after a short time, the 1-RDM is not representable by an ensemble N-electron density matrix (not ensemble N-representable). In this communication, we derive the necessary and sufficient constraints on the Lindbladian matrix within the Lindblad operator to ensure that the 1-RDM remains N-representable for all time. The theory is illustrated by considering the relaxation of an excitation in several molecules F2, N2, CO, and BeH2 subject to environmental noise.

40 keV Shaped electron beam lithography for LIGA intermediate mask fabrication

NARCIS (Netherlands)

Luttge, R.; Adam, D.; Burkhardt, F.; Hoke, F.; Schacke, H.; Schmidt, M.; Wolf, H.; Schmidt, A.

1999-01-01

High precision LIGA masks require a soft X-ray pattern transfer from intermediate masks by means of electron beam lithography. Such a process has been realized using an upgraded Leica ZBA 23 machine with an acceleration voltage of 40 kV. Three process variations of the developer system, so called GG

Differential cross sections for electron-impact vibrational-excitation of tetrahydrofuran at intermediate impact energies

Energy Technology Data Exchange (ETDEWEB)

Do, T. P. T. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); School of Education, Can Tho University, Campus II, 3/2 Street, Xuan Khanh, Ninh Kieu, Can Tho City (Viet Nam); Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Konovalov, D. A.; White, R. D. [College of Science, Technology and Engineering, James Cook University, Townsville (Australia); Brunger, M. J., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Jones, D. B., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia)

2015-03-28

We report differential cross sections (DCSs) for electron-impact vibrational-excitation of tetrahydrofuran, at intermediate incident electron energies (15-50 eV) and over the 10°-90° scattered electron angular range. These measurements extend the available DCS data for vibrational excitation for this species, which have previously been obtained at lower incident electron energies (≤20 eV). Where possible, our data are compared to the earlier measurements in the overlapping energy ranges. Here, quite good agreement was generally observed where the measurements overlapped.

One-step synthesis of high conductivity silver nanoparticle-reduced graphene oxide composite films by electron beam irradiation

Energy Technology Data Exchange (ETDEWEB)

Liu, Gang; Wang, Yujia; Pu, Xianjuan; Jiang, Yong; Cheng, Lingli, E-mail: chenglingli@shu.edu.cn; Jiao, Zheng, E-mail: zjiao@shu.edu.cn

2015-09-15

Graphical abstract: - Highlights: • Both graphene oxide and silver ion were reduced simultaneously by electron beam-based method. • The size of AgNPs can be controlled by changing the irradiation dose of electron beam. • The AgNPs/rGO nanocomposite exhibits much lower sheet resistivity (0.06 Ω m). - Abstract: A rapid, eco-friendly, one-step electron beam (EB)-based method for both the reduction of graphene oxide and loading of Ag nanoparticles (AgNPs) were achieved. Further, the effects of irradiation dose on the morphology of AgNPs and the sheet resistance of Ag nanoparticles/reduced graphene oxide (AgNPs/rGO) were studied. The results reveal that when the irradiation dose increased from 70 kGy to 350 kGy, the size of the AgNPs decreased and became uniformly distributed over the surface of the rGO nanosheets. However the size of the AgNPs increased when the irradiation dose reached 500 kGy. Four-point probe measurement showed that the sheet resistance of the AgNPs/rGO films decreased with decreasing AgNPs size. The lowest sheet resistivity of 0.06 Ω m was obtained in the film corresponding to 350 kGy irradiation dose, which showed a much lower resistivity than the GO film (5.04 × 10{sup 5} Ω m). The formation mechanisms of the as-prepared AgNPs/rGO nanocomposites were proposed. This study provides a fast and eco-friendly EB irradiation induced method to controlling the dimensions of AgNPs/rGO nanocomposites, which can strongly support the mass production of AgNPs/rGO nanocomposites for practical applications.

One-step synthesis of high conductivity silver nanoparticle-reduced graphene oxide composite films by electron beam irradiation

International Nuclear Information System (INIS)

Liu, Gang; Wang, Yujia; Pu, Xianjuan; Jiang, Yong; Cheng, Lingli; Jiao, Zheng

2015-01-01

Graphical abstract: - Highlights: • Both graphene oxide and silver ion were reduced simultaneously by electron beam-based method. • The size of AgNPs can be controlled by changing the irradiation dose of electron beam. • The AgNPs/rGO nanocomposite exhibits much lower sheet resistivity (0.06 Ω m). - Abstract: A rapid, eco-friendly, one-step electron beam (EB)-based method for both the reduction of graphene oxide and loading of Ag nanoparticles (AgNPs) were achieved. Further, the effects of irradiation dose on the morphology of AgNPs and the sheet resistance of Ag nanoparticles/reduced graphene oxide (AgNPs/rGO) were studied. The results reveal that when the irradiation dose increased from 70 kGy to 350 kGy, the size of the AgNPs decreased and became uniformly distributed over the surface of the rGO nanosheets. However the size of the AgNPs increased when the irradiation dose reached 500 kGy. Four-point probe measurement showed that the sheet resistance of the AgNPs/rGO films decreased with decreasing AgNPs size. The lowest sheet resistivity of 0.06 Ω m was obtained in the film corresponding to 350 kGy irradiation dose, which showed a much lower resistivity than the GO film (5.04 × 10 5 Ω m). The formation mechanisms of the as-prepared AgNPs/rGO nanocomposites were proposed. This study provides a fast and eco-friendly EB irradiation induced method to controlling the dimensions of AgNPs/rGO nanocomposites, which can strongly support the mass production of AgNPs/rGO nanocomposites for practical applications

Electronic monitoring and voice prompts improve hand hygiene and decrease nosocomial infections in an intermediate care unit.

Science.gov (United States)

Swoboda, Sandra M; Earsing, Karen; Strauss, Kevin; Lane, Stephen; Lipsett, Pamela A

2004-02-01

To determine whether electronic monitoring of hand hygiene and voice prompts can improve hand hygiene and decrease nosocomial infection rates in a surgical intermediate care unit. Three-phase quasi-experimental design. Phase I was electronic monitoring and direct observation; phase II was electronic monitoring and computerized voice prompts for failure to perform hand hygiene on room exit; and phase III was electronic monitoring only. Nine-room, 14-bed intermediate care unit in a university, tertiary-care institution. All patient rooms, utility room, and staff lavatory were monitored electronically. All healthcare personnel including physicians, nurses, nursing support personnel, ancillary staff, all visitors and family members, and any other personnel interacting with patients on the intermediate care unit. All patients with an intermediate care unit length of stay >48 hrs were followed for nosocomial infection. Electronic monitoring during all phases, computerized voice prompts during phase II only. We evaluated a total of 283,488 electronically monitored entries into a patient room with 251,526 exits for 420 days (10,080 hrs and 3,549 patient days). Compared with phase I, hand hygiene compliance in patient rooms improved 37% during phase II (odds ratio, 1.38; 95% confidence interval, 1.04-1.83) and 41% in phase III (odds ratio, 1.41; 95% confidence interval, 1.07-1.84). When adjusting for patient admissions during each phase, point estimates of nosocomial infections decreased by 22% during phase II and 48% during phase III; when adjusting for patient days, the number of infections decreased by 10% during phase II and 40% during phase III. Although the overall rate of nosocomial infections significantly decreased when combining phases II and III, the association between nosocomial infection and individual phase was not significant. Electronic monitoring provided effective ongoing feedback about hand hygiene compliance. During both the voice prompt phase and post

The energy-deposition model. Electron loss of heavy ions in collisions with neutral atoms at low and intermediate energies

International Nuclear Information System (INIS)

Shevelko, V.P.; Litsarev, M.S.; Kato, D.; Tawara, H.

2010-09-01

Single- and multiple-electron loss processes in collisions of heavy many-electron ions (positive and negative) in collisions with neutral atoms at low and intermediate energies are considered using the energy-deposition model. The DEPOSIT computer code, created earlier to calculate electron-loss cross sections at high projectile energies, is extended for low and intermediate energies. A description of a new version of DEPOSIT code is given, and the limits of validity for collision velocity in the model are discussed. Calculated electron-loss cross sections for heavy ions and atoms (N + , Ar + , Xe + , U + , U 28+ , W, W + , Ge - , Au - ), colliding with neutral atoms (He, Ne, Ar, W) are compared with available experimental and theoretical data at energies E > 10 keV/u. It is found that in most cases the agreement between experimental data and the present model is within a factor of 2. Combining results obtained by the DEPOSIT code at low and intermediate energies with those by the LOSS-R code at high energies (relativistic Born approximation), recommended electron-loss cross sections in a wide range of collision energy are presented. (author)

Cluster Analysis of Time-Dependent Crystallographic Data: Direct Identification of Time-Independent Structural Intermediates

Science.gov (United States)

Kostov, Konstantin S.; Moffat, Keith

2011-01-01

The initial output of a time-resolved macromolecular crystallography experiment is a time-dependent series of difference electron density maps that displays the time-dependent changes in underlying structure as a reaction progresses. The goal is to interpret such data in terms of a small number of crystallographically refinable, time-independent structures, each associated with a reaction intermediate; to establish the pathways and rate coefficients by which these intermediates interconvert; and thereby to elucidate a chemical kinetic mechanism. One strategy toward achieving this goal is to use cluster analysis, a statistical method that groups objects based on their similarity. If the difference electron density at a particular voxel in the time-dependent difference electron density (TDED) maps is sensitive to the presence of one and only one intermediate, then its temporal evolution will exactly parallel the concentration profile of that intermediate with time. The rationale is therefore to cluster voxels with respect to the shapes of their TDEDs, so that each group or cluster of voxels corresponds to one structural intermediate. Clusters of voxels whose TDEDs reflect the presence of two or more specific intermediates can also be identified. From such groupings one can then infer the number of intermediates, obtain their time-independent difference density characteristics, and refine the structure of each intermediate. We review the principles of cluster analysis and clustering algorithms in a crystallographic context, and describe the application of the method to simulated and experimental time-resolved crystallographic data for the photocycle of photoactive yellow protein. PMID:21244840

Photocatalytic Conversion of Nitrobenzene to Aniline through Sequential Proton-Coupled One-Electron Transfers from a Cadmium Sulfide Quantum Dot

Energy Technology Data Exchange (ETDEWEB)

Jensen, Stephen C. [Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States; Bettis Homan, Stephanie [Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States; Weiss, Emily A. [Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States

2016-01-28

This paper describes the use of cadmium sulfide quantum dots (CdS QDs) as visible-light photocatalysts for the reduction of nitrobenzene to aniline through six sequential photoinduced, proton-coupled electron transfers. At pH 3.6–4.3, the internal quantum yield of photons-to-reducing electrons is 37.1% over 54 h of illumination, with no apparent decrease in catalyst activity. Monitoring of the QD exciton by transient absorption reveals that, for each step in the catalytic cycle, the sacrificial reductant, 3-mercaptopropionic acid, scavenges the excitonic hole in ~5 ps to form QD•–; electron transfer to nitrobenzene or the intermediates nitrosobenzene and phenylhydroxylamine then occurs on the nanosecond time scale. The rate constants for the single-electron transfer reactions are correlated with the driving forces for the corresponding proton-coupled electron transfers. This result suggests, but does not prove, that electron transfer, not proton transfer, is rate-limiting for these reactions. Nuclear magnetic resonance analysis of the QD–molecule systems shows that the photoproduct aniline, left unprotonated, serves as a poison for the QD catalyst by adsorbing to its surface. Performing the reaction at an acidic pH not only encourages aniline to desorb but also increases the probability of protonated intermediates; the latter effect probably ensures that recruitment of protons is not rate-limiting.

Controlled cooling of an electronic system for reduced energy consumption

Science.gov (United States)

David, Milnes P.; Iyengar, Madhusudan K.; Schmidt, Roger R.

2016-08-09

Energy efficient control of a cooling system cooling an electronic system is provided. The control includes automatically determining at least one adjusted control setting for at least one adjustable cooling component of a cooling system cooling the electronic system. The automatically determining is based, at least in part, on power being consumed by the cooling system and temperature of a heat sink to which heat extracted by the cooling system is rejected. The automatically determining operates to reduce power consumption of the cooling system and/or the electronic system while ensuring that at least one targeted temperature associated with the cooling system or the electronic system is within a desired range. The automatically determining may be based, at least in part, on one or more experimentally obtained models relating the targeted temperature and power consumption of the one or more adjustable cooling components of the cooling system.

Controlled cooling of an electronic system for reduced energy consumption

Energy Technology Data Exchange (ETDEWEB)

David, Milnes P.; Iyengar, Madhusudan K.; Schmidt, Roger R.

2018-01-30

Energy efficient control of a cooling system cooling an electronic system is provided. The control includes automatically determining at least one adjusted control setting for at least one adjustable cooling component of a cooling system cooling the electronic system. The automatically determining is based, at least in part, on power being consumed by the cooling system and temperature of a heat sink to which heat extracted by the cooling system is rejected. The automatically determining operates to reduce power consumption of the cooling system and/or the electronic system while ensuring that at least one targeted temperature associated with the cooling system or the electronic system is within a desired range. The automatically determining may be based, at least in part, on one or more experimentally obtained models relating the targeted temperature and power consumption of the one or more adjustable cooling components of the cooling system.

Reconstruction of the electron energy distribution function from probe characteristics at intermediate and high pressures

International Nuclear Information System (INIS)

Arslanbekov, R.R.; Kolokolov, N.B.; Kudryavtsev, A.A.; Khromov, N.A.

1991-01-01

Gorbunov et al. have developed a kinetic theory of the electron current drawn by a probe, which substantially extends the region of applicability of the probe method for determining the electron energy distribution function, enabling probes to be used for intermediate and high pressures (up to p ≤ 0.5 atm for monatomic gases). They showed that for λ var-epsilon >> a + d (where a is the probe radius, d is the sheath thickness, and λ var-epsilon is the electron energy relaxation length) the current density j e (V) drawn by the probe is related to the unperturbed distribution function by an integral equation involving the distribution function. The kernal of the integral equation can be written as a function of the diffusion parameter. In the present paper the method of quadrature sums is employed in order to obtain the electron energy distribution function from probe characteristics at intermediate and high pressures. This technique enables them to recover the distribution function from the integral equation when the diffusion parameter has an arbitrary energy dependence ψ 0 (var-epsilon) in any given energy range. The effectiveness of the method is demonstrated by application to both model problems and experimental data

Wearable electronics formed on intermediate layer on textiles

KAUST Repository

Hussain, Muhammad Mustafa

2017-01-01

One manner of producing more desirable clothing with electronic capabilities is to manufacture electronics, such as the charging wires or devices themselves, directly onto the textile materials. Textile materials generally do not support

Interactions in 2D electron and hole systems in the intermediate and ballistic regimes

International Nuclear Information System (INIS)

Proskuryakov, Y Y; Savchenko, A K; Safonov, S S; Li, L; Pepper, M; Simmons, M Y; Ritchie, D A; Linfield, E H; Kvon, Z D

2003-01-01

In different 2D semiconductor systems we study the interaction correction to the Drude conductivity in the intermediate and ballistic regimes, where the parameter k B Tτ/ h-bar changes from 0.1 to 10 (τ is momentum relaxation time). The temperature dependence of the resistance and magnetoresistance in parallel and perpendicular magnetic fields is analysed in terms of the recent theories of electron-electron interactions in systems with different degree of disorder and different character of the fluctuation potential. Generally, good agreement is found between the experiments and the theories

Electronics all-in-one for dummies

CERN Document Server

Ross, Dickon

2013-01-01

Your one-stop UK shop for clear, concise explanations to all the important concepts in electronics and tons of direction for building simple, fun electronic projects. The 8 mini-books in this 1 volume include: Getting Started with ElectronicsWorking with Basic ComponentsWorking with Integrated CircuitsGetting into Alternating CurrentWorking with Radio and InfraredDoing Digital ElectronicsWorking with Basic Stamp ProcessorsBuilding Special Effects With nearly 900 pages of instruction, Electronics All-in-One For Dummies covers all the bases and provides a fascinating hands-on exploration of el

Theoretical treatment of electron capture and excitation in two-electron system ion-atom, atom-atom collisions at low to intermediate energy

International Nuclear Information System (INIS)

Kimura, M.

1986-01-01

A review of various theoretical treatments which have been used to study electron-capture and excitation processes in two-electron-system ion-atom, atom-atom collisions at low to intermediate energy is presented. Advantages as well as limitations associated with these theoretical models in application to practical many-electron ion-atom, atom-atom collisions are specifically pointed out. Although a rigorous theoretical study of many-electron systems has just begun so that reports of theoretical calculations are scarce to date in comparison to flourishing experimental activities, some theoretical results are of great interest and provide important information for understanding collision dynamics of the system which contains many electrons. Selected examples are given for electron capture in a multiply charged ion-He collision, ion-pair formation in an atom-atom collision and alignment and orientation in a Li + + He collision. (Auth.)

Electronic emission produced by light projectiles at intermediate energies

International Nuclear Information System (INIS)

Bernardi, G.C.

1989-01-01

Two aspects of the electronic emission produced by light projectiles of intermediate energies have been studied experimentally. In the first place, measurements of angular distributions in the range from θ = 0 deg -50 deg induced by collisions of 50-200 keV H + incident on He have been realized. It was found that the double differential cross section of electron emission presents a structure focussed in the forward direction and which extends up to relatively large angles. Secondly, the dependence of the double differential cross section on the projectile charge was studied using H + and He 3 2+ projectiles of 50 and 100 keV/amu incident on He. Strong deviations from a constant scaling factor were found for increasing projectile charge. The double differential cross sections and the single differential cross sections as a function of the emission angle, and the ratios of the emissions induced by He 3 2+ and H + at equal incident projectile velocities are compared with the 'Continuum Distorted Wave-Eikonal Initial State' (CDW-EIS) approximation and the 'Classical Trajectory Monte Carlo' (CTMC) method. Both approximations, in which the potential of the projectile exercises a relevant role, reproduce the general aspects of the experimental results. An electron analyzer and the corresponding projectile beam line has been designed and installed; it is characterized by a series of properties which are particularly appropriate for the study of double differential electronic emission in gaseous as well as solid targets. The design permits to assure the conditions to obtain a well localized gaseous target and avoid instrumental distortions of the measured distributions. (Author) [es

One-electron theory of metals

International Nuclear Information System (INIS)

Skriver, H.L.

1984-12-01

The work described in the report and the 16 accompanying publications is based upon a one-electron theory obtained within the local approximation to density-functional theory, and deals with the ground state of metals as obtained from self-consistent electronic-structure calculations performed by means of the Linear Muffin-Tin Orbital (LMTO) method. It has been the goal of the work to establish how well this one-electron approach describes physical properties such as the crystal structures of the transition metals, the structural phase transitions in the alkali, alkaline earth, and rare earth metals, and the localization of 3d, 4f, and 5f electrons in the 3d metal monoxides, the light lanthanides, and the actinides, respectively, as well as the cohesive properties of metals in general. (orig.)

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

Cryo-EM structures of two bovine adenovirus type 3 intermediates

International Nuclear Information System (INIS)

Cheng, Lingpeng; Huang, Xiaoxing; Li, Xiaomin; Xiong, Wei; Sun, Wei; Yang, Chongwen; Zhang, Kai; Wang, Ying; Liu, Hongrong; Huang, Xiaojun; Ji, Gang; Sun, Fei; Zheng, Congyi; Zhu, Ping

2014-01-01

Adenoviruses (Ads) infect hosts from all vertebrate species and have been investigated as vaccine vectors. We report here near-atomic structures of two bovine Ad type 3 (BAd3) intermediates obtained by cryo-electron microscopy. A comparison between the two intermediate structures reveals that the differences are localized in the fivefold vertex region, while their facet structures are identical. The overall facet structure of BAd3 exhibits a similar structure to human Ads; however, BAd3 protein IX has a unique conformation. Mass spectrometry and cryo-electron tomography analyses indicate that one intermediate structure represents the stage during DNA encapsidation, whilst the other intermediate structure represents a later stage. These results also suggest that cleavage of precursor protein VI occurs during, rather than after, the DNA encapsidation process. Overall, our results provide insights into the mechanism of Ad assembly, and allow the first structural comparison between human and nonhuman Ads at backbone level. - Highlights: • First structure of bovine adenovirus type 3. • Some channels are located at the vertex of intermediate during DNA encapsidation. • Protein IX exhibits a unique conformation of trimeric coiled–coiled structure. • Cleavage of precursor protein VI occurs during the DNA encapsidation process

Cryo-EM structures of two bovine adenovirus type 3 intermediates

Energy Technology Data Exchange (ETDEWEB)

Cheng, Lingpeng; Huang, Xiaoxing; Li, Xiaomin [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Xiong, Wei [State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Luo-jia-shan, Wuhan, Hubei 430072 (China); Sun, Wei; Yang, Chongwen; Zhang, Kai; Wang, Ying [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Liu, Hongrong [College of Physics and Information Science, Hunan Normal University, Changsha, Hunan 410081 (China); Huang, Xiaojun; Ji, Gang; Sun, Fei [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Zheng, Congyi, E-mail: cctcc202@whu.edu.cn [State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Luo-jia-shan, Wuhan, Hubei 430072 (China); Zhu, Ping, E-mail: zhup@ibp.ac.cn [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China)

2014-02-15

Adenoviruses (Ads) infect hosts from all vertebrate species and have been investigated as vaccine vectors. We report here near-atomic structures of two bovine Ad type 3 (BAd3) intermediates obtained by cryo-electron microscopy. A comparison between the two intermediate structures reveals that the differences are localized in the fivefold vertex region, while their facet structures are identical. The overall facet structure of BAd3 exhibits a similar structure to human Ads; however, BAd3 protein IX has a unique conformation. Mass spectrometry and cryo-electron tomography analyses indicate that one intermediate structure represents the stage during DNA encapsidation, whilst the other intermediate structure represents a later stage. These results also suggest that cleavage of precursor protein VI occurs during, rather than after, the DNA encapsidation process. Overall, our results provide insights into the mechanism of Ad assembly, and allow the first structural comparison between human and nonhuman Ads at backbone level. - Highlights: • First structure of bovine adenovirus type 3. • Some channels are located at the vertex of intermediate during DNA encapsidation. • Protein IX exhibits a unique conformation of trimeric coiled–coiled structure. • Cleavage of precursor protein VI occurs during the DNA encapsidation process.

Differential cross sections for inelastic scattering of electrons on Kr and Xe atoms at intermediate energies

International Nuclear Information System (INIS)

Filipovic, D.M.

1989-01-01

Electron-impact excitation of the larger- number noble-gas atoms is a way of understanding excitation mechanisms in atomic collisional processes. Krypton and xenon have the largest atomic number of all the stable noble gases. Therefore, effects dependent on the size of a target atom, such as alignment and orientation of the atomic outer shell charge cloud after collisional excitation, are best observed by studying these atoms. Normalized, absolute differential cross sections (DCS's) for the lowest electronic states of Kr and Xe atoms, at intermediate energies, are the subject of this report

Multistate electron transfer dynamics in the condensed phase: Exact calculations from the reduced hierarchy equations of motion approach

International Nuclear Information System (INIS)

Tanaka, Midori; Tanimura, Yoshitaka

2010-01-01

Multiple displaced oscillators coupled to an Ohmic heat bath are used to describe electron transfer (ET) in a dissipative environment. By performing a canonical transformation, the model is reduced to a multilevel system coupled to a heat bath with the Brownian spectral distribution. A reduced hierarchy equations of motion approach is introduced for numerically rigorous simulation of the dynamics of the three-level system with various oscillator configurations, for different nonadiabatic coupling strengths and damping rates, and at different temperatures. The time evolution of the reduced density matrix elements illustrates the interplay of coherences between the electronic and vibrational states. The ET reaction rates, defined as a flux-flux correlation function, are calculated using the linear response of the system to an external perturbation as a function of activation energy. The results exhibit an asymmetric inverted parabolic profile in a small activation regime due to the presence of the intermediate state between the reactant and product states and a slowly decaying profile in a large activation energy regime, which arises from the quantum coherent transitions.

Matrix elements of intraband transitions in quantum dot intermediate band solar cells: the influence of quantum dot presence on the extended-state electron wave-functions

International Nuclear Information System (INIS)

Nozawa, Tomohiro; Arakawa, Yasuhiko

2014-01-01

The intraband transitions which are essential for quantum dot intermediate band solar cells (QD IBSCs) are theoretically investigated by estimating the matrix elements from a ground bound state, which is often regarded as an intermediate band (IB), to conduction band (CB) states for a structure with a quantum dot (QD) embedded in a matrix (a QD/matrix structure). We have found that the QD pushes away the electron envelope functions (probability densities) from the QD region in almost all quantum states above the matrix CB minimum. As a result, the matrix elements of the intraband transitions in the QD/matrix structure are largely reduced, compared to those calculated assuming the envelope functions of free electrons (i.e., plane-wave envelope functions) in a matrix structure as the final states of the intraband transitions. The result indicates the strong influence of the QD itself on the intraband transitions from the IB to the CB states in QD IBSC devices. This work will help in better understanding the problem of the intraband transitions and give new insight, that is, engineering of quantum states is indispensable for the realization of QD IBSCs with high solar energy conversion efficiencies. (paper)

Electrons, pseudoparticles, and quasiparticles in the one-dimensional many-electron problem

International Nuclear Information System (INIS)

Carmelo, J.M.; Castro Neto, A.H.

1996-01-01

We generalize the concept of quasiparticle for one-dimensional (1D) interacting electronic systems. The ↑ and ↓ quasiparticles recombine the pseudoparticle colors c and s (charge and spin at zero-magnetic field) and are constituted by one many-pseudoparticle topological-momentum shift and one or two pseudoparticles. These excitations cannot be separated. We consider the case of the Hubbard chain. We show that the low-energy electron-quasiparticle transformation has a singular character which justifies the perturbative and nonperturbative nature of the quantum problem in the pseudoparticle and electronic basis, respectively. This follows from the absence of zero-energy electron-quasiparticle overlap in 1D. The existence of Fermi-surface quasiparticles both in 1D and three dimensional (3D) many-electron systems suggests their existence in quantum liquids in dimensions 1 1 or whether it becomes finite as soon as we leave 1D remains an unsolved question. copyright 1996 The American Physical Society

Continuous Flow-Resonance Raman Spectroscopy of an Intermediate Redox State of Cytochrome-C

DEFF Research Database (Denmark)

Forster, M.; Hester, R. E.; Cartling, B.

1982-01-01

An intermediate redox state of cytochrome c at alkaline pH, generated upon rapid reduction by sodium dithionite, has been observed by resonance Raman (RR) spectroscopy in combination with the continuous flow technique. The RR spectrum of the intermediate state is reported for excitation both...... in the (alpha, beta) and the Soret optical absorption band. The spectra of the intermediate state are more like those of the stable reduced form than those of the stable oxidized form. For excitation of 514.5 nm, the most prominent indication of an intermediate state is the wave-number shift of one RR band from...... 1,562 cm-1 in the stable oxidized state through 1,535 cm-1 in the intermediate state to 1,544 cm-1 in the stable reduced state. For excitation at 413.1 nm, a band, present at 1,542 cm-1 in the stable reduced state but not present in the stable oxidized state, is absent in the intermediate state. We...

Effects of weak localization in quasi-one-dimensional electronic system over liquid helium

CERN Document Server

Kovdrya, Y Z; Gladchenko, S P

2001-01-01

One measured rho sub x sub x magnetoresistance of a quasi-one-dimensional electronic system over liquid helium within gas scattering range (1.3-2.0 K temperature range). It is shown that with increase of magnetic field the magnetoresistance is reduced at first and them upon passing over minimum it begins to increase from rho sub x sub x approx B sup 2 law. One anticipated that the negative magnetoresistance detected in the course of experiments resulted from the effects of weak localization. The experiment results are in qualitative conformity with the theoretical model describing processes of weak localization in single-dimensional nondegenerate electronic systems

One-Pot Conversion of Carbohydrates into Furan Derivatives via Furfural and 5-Hydroxylmethylfurfural as Intermediates.

Science.gov (United States)

Liu, Bing; Zhang, Zehui

2016-08-23

Recently, there has been growing interest in the transformation of renewable biomass into value-added fuels and chemicals. The catalytic conversion of naturally abundant carbohydrates can generate two-important furan chemicals: 5-hydroxymethylfurfural (HMF) from C6 carbohydrates and furfural from C5 carbohydrates. Both HMF and furfural have received great interest as precursors in the synthesis of commodity chemicals and liquid fuels. In recent years, a trend has emerged to integrate sequential catalytic processes involving multistep reactions for the direct one-pot transformation of carbohydrates into the aimed fuels and chemicals. One-pot reactions have remarkably unique and environmentally friendly benefits, including the fact that isolation and purification of intermediate compounds can be avoided. Herein, the present article aims to review recent advances in the one-pot conversion of carbohydrates into furan derivatives via furfural and HMF as intermediates. Special attention will be paid to the catalytic systems, mechanistic insight, reaction pathways, and catalyst stability. It is expected that this review will guide researchers to develop effective catalytic systems for the one-pot transformation of carbohydrates into furan derivatives. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Excess electrons in methanol clusters: Beyond the one-electron picture

Science.gov (United States)

Pohl, Gábor; Mones, Letif; Turi, László

2016-10-01

We performed a series of comparative quantum chemical calculations on various size negatively charged methanol clusters, ("separators=" CH 3 OH ) n - . The clusters are examined in their optimized geometries (n = 2-4), and in geometries taken from mixed quantum-classical molecular dynamics simulations at finite temperature (n = 2-128). These latter structures model potential electron binding sites in methanol clusters and in bulk methanol. In particular, we compute the vertical detachment energy (VDE) of an excess electron from increasing size methanol cluster anions using quantum chemical computations at various levels of theory including a one-electron pseudopotential model, several density functional theory (DFT) based methods, MP2 and coupled-cluster CCSD(T) calculations. The results suggest that at least four methanol molecules are needed to bind an excess electron on a hydrogen bonded methanol chain in a dipole bound state. Larger methanol clusters are able to form stronger interactions with an excess electron. The two simulated excess electron binding motifs in methanol clusters, interior and surface states, correlate well with distinct, experimentally found VDE tendencies with size. Interior states in a solvent cavity are stabilized significantly stronger than electron states on cluster surfaces. Although we find that all the examined quantum chemistry methods more or less overestimate the strength of the experimental excess electron stabilization, MP2, LC-BLYP, and BHandHLYP methods with diffuse basis sets provide a significantly better estimate of the VDE than traditional DFT methods (BLYP, B3LYP, X3LYP, PBE0). A comparison to the better performing many electron methods indicates that the examined one-electron pseudopotential can be reasonably used in simulations for systems of larger size.

Single turnover studies of oxidative halophenol dehalogenation by horseradish peroxidase reveal a mechanism involving two consecutive one electron steps: toward a functional halophenol bioremediation catalyst.

Science.gov (United States)

Sumithran, Suganya; Sono, Masanori; Raner, Gregory M; Dawson, John H

2012-12-01

Horseradish peroxidase (HRP) catalyzes the oxidative para-dechlorination of the environmental pollutant/carcinogen 2,4,6-trichlorophenol (2,4,6-TCP). A possible mechanism for this reaction is a direct oxygen atom transfer from HRP compound I (HRP I) to trichlorophenol to generate 2,6-dichloro 1,4-benzoquinone, a two-electron transfer process. An alternative mechanism involves two consecutive one-electron transfer steps in which HRP I is reduced to compound II (HRP II) and then to the ferric enzyme as first proposed by Wiese et al. [F.W. Wiese, H.C. Chang, R.V. Lloyd, J.P. Freeman, V.M. Samokyszyn, Arch. Environ. Contam. Toxicol. 34 (1998) 217-222]. To probe the mechanism of oxidative halophenol dehalogenation, the reactions between 2,4,6-TCP and HRP compounds I or II have been investigated under single turnover conditions (i.e., without excess H(2)O(2)) using rapid scan stopped-flow spectroscopy. Addition of 2,4,6-TCP to HRP I leads rapidly to HRP II and then more slowly to the ferric resting state, consistent with a mechanism involving two consecutive one-electron oxidations of the substrate via a phenoxy radical intermediate. HRP II can also directly dechlorinate 2,4,6-TCP as judged by rapid scan stopped-flow and mass spectrometry. This observation is particularly significant since HRP II can only carry out one-electron oxidations. A more detailed understanding of the mechanism of oxidative halophenol dehalogenation will facilitate the use of HRP as a halophenol bioremediation catalyst. Copyright © 2012 Elsevier Inc. All rights reserved.

Photo-driven electron transfer from the highly reducing excited state of naphthalene diimide radical anion to a CO ₂ reduction catalyst within a molecular triad

Energy Technology Data Exchange (ETDEWEB)

Martinez, Jose F. [Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center; Northwestern University; Evanston; USA; La Porte, Nathan T. [Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center; Northwestern University; Evanston; USA; Mauck, Catherine M. [Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center; Northwestern University; Evanston; USA; Wasielewski, Michael R. [Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center; Northwestern University; Evanston; USA

2017-01-01

The naphthalene-1,4:5,8-bis(dicarboximide) radical anion (NDI^-˙), which is easily produced by mild chemical or electrochemical reduction (-0.5 Vvs.SCE), can be photoexcited at wavelengths as long as 785 nm, and has an excited state (NDI^-˙*) oxidation potential of -2.1 Vvs.SCE, making it a very attractive choice for artificial photosynthetic systems that require powerful photoreductants, such as CO₂ reduction catalysts. However, once an electron is transferred from NDI^-˙* to an acceptor directly bound to it, a combination of strong electronic coupling and favorable free energy change frequently make the back electron transfer rapid. To mitigate this effect, we have designed a molecular triad system comprising an NDI^-˙ chromophoric donor, a 9,10-diphenylanthracene (DPA) intermediate acceptor, and a Re(dmb)(CO)₃carbon dioxide reduction catalyst, where dmb is 4,4'-dimethyl-2,2'-bipyridine, as the terminal acceptor. Photoexcitation of NDI^-˙ to NDI^-˙* is followed by ultrafast reduction of DPA to DPA^-˙, which then rapidly reduces the metal complex. The overall time constant for the forward electron transfer to reduce the metal complex is τ = 20.8 ps, while the time constant for back-electron transfer is six orders of magnitude longer, τ = 43.4 μs. Achieving long-lived, highly reduced states of these metal complexes is a necessary condition for their use as catalysts. The extremely long lifetime of the reduced metal complex is attributed to careful tuning of the redox potentials of the chromophore and intermediate acceptor. The NDI^-˙–DPA fragment presents many attractive features for incorporation into other photoinduced electron transfer assemblies directed at the long-lived photosensitization of difficult-to-reduce catalytic centers.

The magnetized electron-acoustic instability driven by a warm, field-aligned electron beam

International Nuclear Information System (INIS)

Sooklal, A.; Mace, R.L.

2004-01-01

The electron-acoustic instability in a magnetized plasma having three electron components, one of which is a field-aligned beam of intermediate temperature, is investigated. When the plasma frequency of the cool electrons exceeds the electron gyrofrequency, the electron-acoustic instability 'bifurcates' at sufficiently large propagation angles with respect to the magnetic field to yield an obliquely propagating, low-frequency electron-acoustic instability and a higher frequency cyclotron-sound instability. Each of these instabilities retains certain wave features of its progenitor, the quasiparallel electron-acoustic instability, but displays also new magnetic qualities through its dependence on the electron gyrofrequency. The obliquely propagating electron-acoustic instability requires a lower threshold beam speed for its excitation than does the cyclotron-sound instability, and for low to intermediate beam speeds has the higher maximum growth rate. When the plasma is sufficiently strongly magnetized that the plasma frequency of the cool electrons is less than the electron gyrofrequency, the only instability in the electron-acoustic frequency range is the strongly magnetized electron-acoustic instability. Its growth rate and real frequency exhibit a monotonic decrease with wave propagation angle and it grows at small to intermediate wave numbers where its parallel phase speed is approximately constant. The relevance of the results to the interpretation of cusp auroral hiss and auroral broadband electrostatic noise is briefly discussed

Joint refinement model for the spin resolved one-electron reduced density matrix of YTiO3 using magnetic structure factors and magnetic Compton profiles data.

Science.gov (United States)

Gueddida, Saber; Yan, Zeyin; Kibalin, Iurii; Voufack, Ariste Bolivard; Claiser, Nicolas; Souhassou, Mohamed; Lecomte, Claude; Gillon, Béatrice; Gillet, Jean-Michel

2018-04-28

In this paper, we propose a simple cluster model with limited basis sets to reproduce the unpaired electron distributions in a YTiO 3 ferromagnetic crystal. The spin-resolved one-electron-reduced density matrix is reconstructed simultaneously from theoretical magnetic structure factors and directional magnetic Compton profiles using our joint refinement algorithm. This algorithm is guided by the rescaling of basis functions and the adjustment of the spin population matrix. The resulting spin electron density in both position and momentum spaces from the joint refinement model is in agreement with theoretical and experimental results. Benefits brought from magnetic Compton profiles to the entire spin density matrix are illustrated. We studied the magnetic properties of the YTiO 3 crystal along the Ti-O 1 -Ti bonding. We found that the basis functions are mostly rescaled by means of magnetic Compton profiles, while the molecular occupation numbers are mainly modified by the magnetic structure factors.

Detection of bump-on-tail reduced electron velocity distributions at the electron foreshock boundary

International Nuclear Information System (INIS)

Fitzenreiter, R.J.; Klimas, A.J.; Scudder, J.D.

1984-02-01

Reduced velocity distributions are derived from three-dimensional measurements of the velocity distribution of electrons in the 7 to 500 eV range in the electron foreshock. Bump-on-tail reduced distributions are presented for the first time at the foreshock boundary consistent with Filbert and Kellogg's proposed time-of-flight mechanism for generating the electron beams. In a significant number of boundary crossings, bump-on-tail reduced distributions were found in consecutive 3 sec measurements made 9 sec apart. It is concluded that, although the beams are linearly unstable to plasma waves according to the Penrose criterion, they persist on a time scale of 3 to 15 sec

Evolving ONe WD+He star systems to intermediate-mass binary pulsars

Science.gov (United States)

Liu, D.; Wang, B.; Chen, W.; Zuo, Z.; Han, Z.

2018-06-01

It has been suggested that accretion-induced collapse (AIC) is a non-negligible path for the formation of the observed neutron stars (NSs). An ONe white dwarf (WD) that accretes material from a He star may experience AIC process and eventually produce intermediate-mass binary pulsars (IMBPs), named as the ONe WD+He star scenario. Note that previous studies can only account for part of the observed IMBPs with short orbital periods. In this work, we investigate the evolution of about 900 ONe WD+He star binaries to explore the distribution of IMBPs. We found that the ONe WD+He star scenario could form IMBPs including pulsars with 5-340 ms spin periods and 0.75-1.38 M_{⊙} WD companions, in which the orbital periods range from 0.04 to 900 d. Compared with the 20 observed IMBPs, this scenario can cover the parameters of 13 sources in the final orbital period-WD mass plane and the Corbet diagram, most of which have short orbital periods. We found that the ONe WD+He star scenario can explain almost all the observed IMBPs with short orbital periods. This work can well match the observed parameters of PSR J1802-2124 (one of the two precisely observed IMBPs), providing a possible evolutional path for its formation. We also speculate that the compact companion of HD 49798 (a hydrogen depleted sdO6 star) may be not a NS based on this work.

One electron oxidation of Ni(II)-iminodiacetate by carbonate radical

International Nuclear Information System (INIS)

Mandal, P.C.; Bardhan, D.K.; Bhattacharyya, S.N.

1995-01-01

Reactions of carbonate radical (CO 3 - ), generated by photolysis or by radiolysis of a carbonate solution with nickel(II)-iminodiacetate (Ni(II)IDA) were studied at pH 10.5 and ionic strength (I)=0.2 mol x dm -3 . The stable product arising from the ligand degradation in the complex is mainly glyoxalic acid. Time-resolved spectroscopy and transient kinetics were studied using flash photolysis. From the kinetic data it was suggested that the carbonate radical initially reacts with Ni(III)IDA with a rate constant (2.4.±0.4) x 10 6 dm 3 x mol -1 x s -1 to form a Ni(II)IDA species which, however, undergoes a first-order transformation (k=2.7 x 10 2 x s -1 ) to give a radical intermediate of the type Ni(II)RNHCHCO - 2 ) which rapidly forms an adduct containing a Ni-C bond. This adduct decays very slowly to give rise to glyoxalic acid. From a consideration of equilibrium between Ni(II)IDA and Ni(III)IDA, the one electron reduction potential for the Ni(III)IDA/Ni(II)IDA couple was determined to be 1.467 V. (author) 30 refs.; 5 figs

Electron capture in low- and intermediate-energy collisions between completely stripped light ions and metastable H(2s) targets

International Nuclear Information System (INIS)

Blanco, S.A.; Falcon, C.A.; Reinhold, C.O.; Casaubon, J.I.; Piacentini, R.D.

1987-01-01

Total cross sections for electron capture from H(2s) targets by He 2+ ions have been computed in the impact velocity range 0.05-0.5 au. Calculations were performed using a molecular close-coupling approach with inclusion of electron translation factors. A ten-state molecular basis set was considered. A comparison is made with Landau-Zener results for the same system. Intermediate projectile energy classical Monte Carlo capture cross sections are also presented for H + , He 2+ , Li 3+ and C 6+ projectiles. (author)

Antibonding intermediate state in the theory of vibrational excitation of diatomic molecules by slow electrons

International Nuclear Information System (INIS)

Kazanskii, A.K.

1982-01-01

An exactly solvable model is constructed for the description of the processes that take place when a slow electron collides with a diatomic molecule (vibrational excitation, associative detachment, and dissociative attachment). As a particular model of the variant, the case of an antibonding (virtual) state of an intermediate state is considered, and a term of this state is parametrized in a very simple manner. The vibrational excitation and dissociative attachment are calculated for a system corresponding to the HCl molecule. The results are in good qualitative agreement with experiment

Rapid pulse annealing of CdZnTe detectors for reducing electronic noise

Science.gov (United States)

Voss, Lars; Conway, Adam; Nelson, Art; Nikolic, Rebecca J.; Payne, Stephen A.; Swanberg, Jr., Erik Lars

2018-05-01

A combination of doping, rapid pulsed optical and/or thermal annealing, and unique detector structure reduces or eliminates sources of electronic noise in a CdZnTe (CZT) detector. According to several embodiments, methods of forming a detector exhibiting minimal electronic noise include: pulse-annealing at least one surface of a detector comprising CZT for one or more pulses, each pulse having a duration of .about.0.1 seconds or less. The at least one surface may optionally be ion-implanted. In another embodiment, a CZT detector includes a detector surface with two or more electrodes operating at different electric potentials and coupled to the detector surface; and one or more ion-implanted CZT surfaces on or in the detector surface, each of the one or more ion-implanted CZT surfaces being independently connected to one of the two or more electrodes and the surface of the detector. At least two of the ion-implanted surfaces are in electrical contact.

An experimental investigation on reduced radiological penumbra for intermediate energy x-rays: Implications for small field radiosurgery

Science.gov (United States)

Keller, Brian Michael

Current day external beam radiation therapy typically uses x-ray energies in the megavoltage (6--18 MV) or in the superficial/orthovoltage (80--350 kVp) energy ranges. It has been found that intermediate energy x-rays (those greater than orthovoltage but sub-megavoltage) may offer an advantage in the field of high precision radiation therapy such as in radiosurgery. This advantage is a reduction in the radiological penumbra associated with small (less than about 3 cm) radiation dose fields. A consequence of reduced radiological penumbra is a more homogenous, conformal dose distribution in the patient with dose escalation and organ sparing made more feasible. The objectives of this thesis were as follows: to produce and to characterize an intermediate energy x-ray beam, to establish a method of accurate penumbra measurement at the micron level for millimeter size fields, to measure the radiological penumbra of single small intermediate energy x-ray fields, and to show the clinical consequences of a multiple beam irradiation in a stereotactic head phantom. A maximum photon energy of 1.2 +/- 0.1 MeV was determined for the intermediate energy x-ray spectrum at the expense of a low dose rate. A digital microscope with a computer controlled translation stage was investigated for its ability to resolve steep dose gradients in Gafchromic EBT film for field sizes as small as 1 mm and for photon energies as low as 100 kVp. The microscope-film system resolved gradients to within about 30 mum, limited by the inherent spatial resolution of the film, the noise of the system, and the uncertainties of measurement. Penumbra widths were compared for 1.2 MV versus 6 MV for identical irradiation conditions. In some instances, there was a five-fold reduction in the radiological penumbra of single 1.2 MV x-ray beams. A multiple beam arc irradiation demonstrated that the advantages seen with single beams carry over to multiple beams. The benefits of reduced radiological penumbra for

One-dimensional free-electron laser equations without the slowly varying envelope approximation

Directory of Open Access Journals (Sweden)

C. Maroli

2011-07-01

Full Text Available A set of one-dimensional equations has been deduced in the time domain from the Maxwell-Lorentz system with the aim of describing the free-electron laser radiation without using the slowly varying envelope approximation (SVEA. These equations are valid even in the case of arbitrarily short electron bunches and of current distributions with ripples on the scale of or shorter than the wavelength. Numerical examples are presented, showing that for long homogeneous bunches the new set of equations gives results in agreement with the SVEA free-electron laser theory and that the use of short or prebunched electron beams leads to a decrease of the emission lethargy. Furthermore, we demonstrate that in all cases in which the backward low frequency wave has negligible effects, these equations can be reduced to a form similar to the usual 1D SVEA equations but with a different definition of the bunching term.

Electron-phonon coupling in one dimension

International Nuclear Information System (INIS)

Apostol, M.; Baldea, I.

1981-08-01

The Ward identity is derived for the electron-phonon coupling in one dimension and the spectrum of elementary excitations is calculated by assuming that the Fermi distribution is not strongly distorted by interaction. The electron-phonon vertex is renormalized in the case of the forward scattering and Migdal's theorem is discussed. A model is proposed for the giant Kohn anomaly. The dip in the phonon spectrum is obtained and found to be in agreement with the experimental data for KCP. (author)

One- and zero-dimensional electron systems over liquid helium (Review article)

CERN Document Server

Kovdrya, Y Z

2003-01-01

Experimental and theoretical investigations of one-dimensional and zero-dimensional electron systems near the liquid helium surface are surveyed. The properties of electron states over the plane surface of liquid helium including thin layers of helium are considered. The methods of realization of one- and zero-dimensional electron systems are discussed, and the results of experimental and theoretical investigations of their properties are given. The experiments with localization processes in a quasi-one-dimensional electron systems on liquid helium are described. The collective effects in one-dimensional and quasi-one-dimensional electron systems are considered, and the point of possible application of low-dimensional electron systems on liquid helium in electron devices and quantum computers is discussed.

Interference electron microscopy of one-dimensional electron-optical phase objects

International Nuclear Information System (INIS)

Fazzini, P.F.; Ortolani, L.; Pozzi, G.; Ubaldi, F.

2006-01-01

The application of interference electron microscopy to the investigation of electron optical one-dimensional phase objects like reverse biased p-n junctions and ferromagnetic domain walls is considered. In particular the influence of diffraction from the biprism edges on the interference images is analyzed and the range of applicability of the geometric optical equation for the interpretation of the interference fringe shifts assessed by comparing geometric optical images with full wave-optical simulations. Finally, the inclusion of partial spatial coherence effects are discussed

Single electron capture differential cross section in H+ + He collisions at intermediate and high collision energies

International Nuclear Information System (INIS)

Abufager, P N; Fainstein, P D; MartInez, A E; Rivarola, R D

2005-01-01

The generalized continuum distorted wave-eikonal initial state (CDW-EIS II) approximation is employed to study differential cross sections (DCS) for single electron capture in H + + He collisions at intermediate and high energies. Present results are compared with theoretical calculations obtained using the previous CDW-EIS formulation in order to show the importance of the description of the bound and continuum target states in the entrance and exit channels, respectively. Both DCS are also shown together with other theoretical results and with experimental data

Spectral studies of intermediate species formed in one-electron reactions of bovine liver catalase at room and low temperatures. A comparison with peroxidase reactions

International Nuclear Information System (INIS)

Metodiewa, D.; Dunford, H.B.

1992-01-01

The reactions of native bovine catalase with superoxide and solvated electrons have been investigated using three different methods for generating these reducing substrates: γ-radiolysis of oxygenated or deaerated buffer solutions in the presence of an OH radical scavenger; either xanthine or acetaldehyde with xanthine oxidase; and low-temperature (77 K) γ-radiolysis of buffered ethylene glycol/water solutions with subsequent annealing of samples at 183 K. (Author)

On the applicability of one- and many-electron quantum chemistry models for hydrated electron clusters

Science.gov (United States)

Turi, László

2016-04-01

We evaluate the applicability of a hierarchy of quantum models in characterizing the binding energy of excess electrons to water clusters. In particular, we calculate the vertical detachment energy of an excess electron from water cluster anions with methods that include one-electron pseudopotential calculations, density functional theory (DFT) based calculations, and ab initio quantum chemistry using MP2 and eom-EA-CCSD levels of theory. The examined clusters range from the smallest cluster size (n = 2) up to nearly nanosize clusters with n = 1000 molecules. The examined cluster configurations are extracted from mixed quantum-classical molecular dynamics trajectories of cluster anions with n = 1000 water molecules using two different one-electron pseudopotenial models. We find that while MP2 calculations with large diffuse basis set provide a reasonable description for the hydrated electron system, DFT methods should be used with precaution and only after careful benchmarking. Strictly tested one-electron psudopotentials can still be considered as reasonable alternatives to DFT methods, especially in large systems. The results of quantum chemistry calculations performed on configurations, that represent possible excess electron binding motifs in the clusters, appear to be consistent with the results using a cavity structure preferring one-electron pseudopotential for the hydrated electron, while they are in sharp disagreement with the structural predictions of a non-cavity model.

On the applicability of one- and many-electron quantum chemistry models for hydrated electron clusters

Energy Technology Data Exchange (ETDEWEB)

Turi, László, E-mail: turi@chem.elte.hu [Department of Physical Chemistry, Eötvös Loránd University, P.O. Box 32, H-1518 Budapest 112 (Hungary)

2016-04-21

We evaluate the applicability of a hierarchy of quantum models in characterizing the binding energy of excess electrons to water clusters. In particular, we calculate the vertical detachment energy of an excess electron from water cluster anions with methods that include one-electron pseudopotential calculations, density functional theory (DFT) based calculations, and ab initio quantum chemistry using MP2 and eom-EA-CCSD levels of theory. The examined clusters range from the smallest cluster size (n = 2) up to nearly nanosize clusters with n = 1000 molecules. The examined cluster configurations are extracted from mixed quantum-classical molecular dynamics trajectories of cluster anions with n = 1000 water molecules using two different one-electron pseudopotenial models. We find that while MP2 calculations with large diffuse basis set provide a reasonable description for the hydrated electron system, DFT methods should be used with precaution and only after careful benchmarking. Strictly tested one-electron psudopotentials can still be considered as reasonable alternatives to DFT methods, especially in large systems. The results of quantum chemistry calculations performed on configurations, that represent possible excess electron binding motifs in the clusters, appear to be consistent with the results using a cavity structure preferring one-electron pseudopotential for the hydrated electron, while they are in sharp disagreement with the structural predictions of a non-cavity model.

Electronic states in systems of reduced dimensionality

International Nuclear Information System (INIS)

Ulloa, S.E.

1992-01-01

This report briefly discusses the following research: magnetically modulated systems, inelastic magnetotunneling, ballistic transport review, screening in reduced dimensions, raman and electron energy loss spectroscopy; and ballistic quantum interference effects. (LSP)

Structural, dynamic, electronic, and vibrational properties of flexible, intermediate, and stressed rigid As-Se glasses and liquids from first principles molecular dynamics

International Nuclear Information System (INIS)

Bauchy, M.; Kachmar, A.; Micoulaut, M.

2014-01-01

The structural, vibrational, electronic, and dynamic properties of amorphous and liquid As x Se 1-x (0.10 intermediate phase in these glassy networks, observed at 0.27 one derived from mean-field approaches of stiffness transitions

Photo- and radiation chemical studies of intermediates involved in excited-state electron-transfer reactions

International Nuclear Information System (INIS)

Hoffman, M.Z.

1985-01-01

Excited-state inter- and intramolecular electron-transfer reactions lie at the heart of the most photochemical solar energy conversion schemes. The authors research, which has utilized the techniques of continuous and pulsed photolysis and radiolysis, has focused on three general aspects of these reactions involving transition metal coordination complexes and electron donor-acceptor complexes: i) the effect of solution medium on the properties and quenching of the excited states; ii) the control of the quantum yields of formation of redox products; iii) the mechanism by which reduced species interact with water to yield H 2 homogeneously and heterogeneously. EDTA is among the most popular sacrificial electron donors used in model systems. Its role is to scavenge the oxidized form of the photosensitizer in order to prevent its rapid reaction with the reduced form of the electron relay species that results from the electron-transfer quenching of the excited photosensitizer. In systems involving MV 2+ , the radicals resulting from the oxidation of EDTA can eventually lead to the generation of a second equivalent of MV + ; the reducing agent is believed to be a radical localized on the carbon atom alpha to the carboxylate group. The reaction of radiolytically-generated OH/H with EDTA produces this radical directly via H-abstraction or indirectly via deprotonation of the carbon atom adjacent to the nitrogen radical site in the oxidized amine moiety; it reduces MV 2+ with rate constants of 2.8 x 10 9 , 7.6 x 10 9 , and 8.5 x 10 6 M -1 s -1 at pH 12.5, 8.3, and 4.7, respectively. Degradative decarboxylation of EDTA-radicals and their back electron-transfer reactions are enhanced in acidic solution causing the yield of MV + to be severely diminished

One-electron transfer reactions of the couple NAD./NADH

International Nuclear Information System (INIS)

Grodkowski, J.; Neta, P.; Carlson, B.W.; Miller, L.

1983-01-01

One-electron transfer reactions involving nicotinamide-adenine dinucleotide in its oxidized and reducd forms (NAD./NADH) were studied by pulse radiolysis in aqueous solutions. One-electron oxidation of NADH by various phenoxyl radicals and phenothiazine cation radicals was found to take place with rate constants in the range of 10 5 to 10 8 M -1 s -1 , depending on the redox potential of the oxidizing species. In all cases, NAD. is formed quantitatively with no indication for the existence of the protonated form (NADH + .). The spectrum of NAD., as well as the rates of oxidation of NADH by phenoxyl and by (chlorpromazine) + . were independent of pH between pH 4.5 and 13.5. Reaction of deuterated NADH indicated only a small kinetic isotope effect. All these findings point to an electron transfer mechanism. On the other hand, attempts to observe the reverse electron transfer, i.e., one-electron reduction of NAD. to NADH by radicals such as semiquinones, showed that k was less than 10 4 to 10 5 M -1 s -1 , so that it was unobservable. Consequently, it was not possible to achieve equilibrium conditions which would have permitted the direct measurement of the redox potential for NAD./NADH. One-electron reduction of NAD. appears to be an unlikely process. 1 table

Indirect contributions to electron-impact ionization of Li+ (1 s 2 s S31 ) ions: Role of intermediate double-K -vacancy states

Science.gov (United States)

Müller, A.; Borovik, A.; Huber, K.; Schippers, S.; Fursa, D. V.; Bray, I.

2018-02-01

Fine details of the cross section for electron-impact ionization of metastable two-electron Li+(1 s 2 s S31) ions are scrutinized by both experiment and theory. Beyond direct knockoff ionization, indirect ionization mechanisms proceeding via formation of intermediate double-K-vacancy (hollow) states either in a Li+ ion or in a neutral lithium atom and subsequent emission of one or two electrons, respectively, can contribute to the net production of Li2 + ions. The partial cross sections for such contributions are less than 4% of the total single-ionization cross section. The characteristic steps, resonances, and interference phenomena in the indirect ionization contribution are measured with an experimental energy spread of less than 0.9 eV and with a statistical relative uncertainty of the order of 1.7%, requiring a level of statistical uncertainty in the total single-ionization cross section of better than 0.05%. The measurements are accompanied by convergent-close-coupling calculations performed on a fine energy grid. Theory and experiment are in remarkable agreement concerning the fine details of the ionization cross section. Comparison with previous R-matrix results is less favorable.

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

Electronic field emission models beyond the Fowler-Nordheim one

Science.gov (United States)

Lepetit, Bruno

2017-12-01

We propose several quantum mechanical models to describe electronic field emission from first principles. These models allow us to correlate quantitatively the electronic emission current with the electrode surface details at the atomic scale. They all rely on electronic potential energy surfaces obtained from three dimensional density functional theory calculations. They differ by the various quantum mechanical methods (exact or perturbative, time dependent or time independent), which are used to describe tunneling through the electronic potential energy barrier. Comparison of these models between them and with the standard Fowler-Nordheim one in the context of one dimensional tunneling allows us to assess the impact on the accuracy of the computed current of the approximations made in each model. Among these methods, the time dependent perturbative one provides a well-balanced trade-off between accuracy and computational cost.

Distorted wave models applied to electron emission study in ion-atom collisions at intermediate and high energies

International Nuclear Information System (INIS)

Fainstein, P.D.

1989-01-01

The electron emission from different atoms induced by impact of multicharged bare ions at intermediate and high energies is studied. To perform these studies, the continuum distorted wave-eikonal initial state model is used. With this distorted wave model, analytical expressions are obtained for the transition amplitudes as a function of the transverse momentum transfer for hydrogen targets in an arbitrary initial state and for every any orbital of a multielectronic target represented as a linear combination of Slater type orbitals. With these expressions, the different cross sections which are compared with the experimental data available are numerically calculated. The results obtained for different targets and projectiles and the comparison with other theoretical models and experimental data allows to explain the electron emission spectra and to predict new effects which have not been measured so far. The results of the present work permit to view the ionization process as the evolution of the active electron in the combined field of the target and projectile nuclei. (Author) [es

Direct Structural and Chemical Characterization of the Photolytic Intermediates of Methylcobalamin Using Time-Resolved X-ray Absorption Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Subramanian, Ganesh; Zhang, Xiaoyi; Kodis, Gerdenis; Kong, Qingyu; Liu, Cunming; Chizmeshya, Andrew; Weierstall, Uwe; Spence, John

2018-04-05

Cobalt−carbon bond cleavage is crucial to most natural and synthetic applications of the cobalamin class of compounds, and here we present the first direct electronic and geometric structural characteristics of intermediates formed following photoexcitation of methylcobalamin (MeCbl) using time-resolved X-ray absorption spectroscopy (XAS). We catch transients corresponding to two intermediates, in the hundreds of picoseconds and a few microseconds. Highlights of the picosecond intermediate, which is reduced in comparison to the ground state, are elongation of the upper axial Co−C bond and relaxation of the corrin ring. This is not so with the recombining photocleaved products captured at a few microseconds, where the Co−C bond almost (yet not entirely) reverts to its ground state configuration and a substantially elongated lower axial Co−NIm bond is observed. The reduced cobalt site here confirms formation of methyl radical as the photoproduct.

3,4-Dihydro-1,3-2H-benzoxazines: Novel reducing agents through one electron donation mechanism and their application as the formation of nano-metallic silver coating

Energy Technology Data Exchange (ETDEWEB)

Kaewvilai, Attaphon [Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand); Wattanathana, Worawat [Department of Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand); Jongrungruangchok, Suchada [Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Rangsit University, Pathumthani, 12000 (Thailand); Veranitisagul, Chatchai [Department of Material and Metallurgical Engineering, Faculty of Engineering, Rajamangala University of Technology Thanyaburi, Klong 6, Thanyaburi, Pathumthani, 12110 (Thailand); Koonsaeng, Nattamon [Department of Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand); Laobuthee, Apirat, E-mail: fengapl@ku.ac.th [Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand)

2015-11-01

3,4-dihydro-1,3-2H-benzoxazines as novel one-electron donators for silver(I) ion into nano-metallic silver was firstly found and reported. The silver formation from nano-spherical particles to coral-like and dendrite-like structures was presented. With respect to the characterization results, the feasible reaction mechanism of the silver formation was proposed as an electron donated from benzoxazine to silver(I) ion, resulting in a radical cationic species of benzoxazine and silver(0). Based on this reduction process, a new approach for nano-silver coating on various surfaces such as fumed silica (SiO{sub 2}), titanium dioxide (TiO{sub 2}), carbon black (CB), chitosan (CS) including plastic sheet (polycarbonate, PC) and pellet (polyvinyl alcohol, PVA), was also revealed. Besides the nano-silver coated products were applied as antimicrobials fillers for Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Micrococcus luteus ATCC 9341, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 2785 and Candida albicans ATCC 10231. - Highlights: • Benzoxazines were discovered to be novel reducing agents for silver(I) ion. • The speculated mechanism of the one electron donation process was investigated. • Dendrite structure of silver was formed from spherical silver nanoparticles. • A new approach for nano metallic-silver coating on various surfaces was revealed. • The nano-silver coated products were applied as antimicrobials fillers.

3,4-Dihydro-1,3-2H-benzoxazines: Novel reducing agents through one electron donation mechanism and their application as the formation of nano-metallic silver coating

International Nuclear Information System (INIS)

Kaewvilai, Attaphon; Wattanathana, Worawat; Jongrungruangchok, Suchada; Veranitisagul, Chatchai; Koonsaeng, Nattamon; Laobuthee, Apirat

2015-01-01

3,4-dihydro-1,3-2H-benzoxazines as novel one-electron donators for silver(I) ion into nano-metallic silver was firstly found and reported. The silver formation from nano-spherical particles to coral-like and dendrite-like structures was presented. With respect to the characterization results, the feasible reaction mechanism of the silver formation was proposed as an electron donated from benzoxazine to silver(I) ion, resulting in a radical cationic species of benzoxazine and silver(0). Based on this reduction process, a new approach for nano-silver coating on various surfaces such as fumed silica (SiO_2), titanium dioxide (TiO_2), carbon black (CB), chitosan (CS) including plastic sheet (polycarbonate, PC) and pellet (polyvinyl alcohol, PVA), was also revealed. Besides the nano-silver coated products were applied as antimicrobials fillers for Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Micrococcus luteus ATCC 9341, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 2785 and Candida albicans ATCC 10231. - Highlights: • Benzoxazines were discovered to be novel reducing agents for silver(I) ion. • The speculated mechanism of the one electron donation process was investigated. • Dendrite structure of silver was formed from spherical silver nanoparticles. • A new approach for nano metallic-silver coating on various surfaces was revealed. • The nano-silver coated products were applied as antimicrobials fillers.

Microbially-reduced graphene scaffolds to facilitate extracellular electron transfer in microbial fuel cells.

Science.gov (United States)

Yuan, Yong; Zhou, Shungui; Zhao, Bo; Zhuang, Li; Wang, Yueqiang

2012-07-01

A one-pot method is exploited by adding graphene oxide (GO) and acetate into an microbial fuel cell (MFC) in which GO is microbially reduced, leading to in situ construction of a bacteria/graphene network in the anode. The obtained microbially reduced graphene (MRG) exhibits comparable conductivity and physical characteristics to the chemically reduced graphene. Electrochemical measurements reveal that the number of exoelectrogens involved in extracellular electron transfer (EET) to the solid electrode, increases due to the presence of graphene scaffolds, and the EET is facilitated in terms of electron transfer kinetics. As a result, the maximum power density of the MFC is enhanced by 32% (from 1440 to 1905 mW m(-2)) and the coulombic efficiency is improved by 80% (from 30 to 54%). The results demonstrate that the construction of the bacteria/graphene network is an effective alternative to improve the MFC performance. Copyright © 2012 Elsevier Ltd. All rights reserved.

Direct, coherent and incoherent intermediate state tunneling and scanning tunnel microscopy (STM)

International Nuclear Information System (INIS)

Halbritter, J.

1997-01-01

Theory and experiment in tunneling are still qualitative in nature, which hold true also for the latest developments in direct-, resonant-, coherent- and incoherent-tunneling. Those tunnel processes have recently branched out of the field of ''solid state tunnel junctions'' into the fields of scanning tunnel microscopy (STM), single electron tunneling (SET) and semiconducting resonant tunnel structures (RTS). All these fields have promoted the understanding of tunneling in different ways reaching from the effect of coherence, of incoherence and of charging in tunneling, to spin flip or inelastic effects. STM allows not only the accurate measurements of the tunnel current and its voltage dependence but, more importantly, the easy quantification via the (quantum) tunnel channel conductance and the distance dependence. This new degree of freedom entering exponentially the tunnel current allows an unique identification of individual tunnel channels and their quantification. In STM measurements large tunnel currents are observed for large distances d > 1 nm explainable by intermediate state tunneling. Direct tunneling with its reduced tunnel time and reduced off-site Coulomb charging bridges distances below 1 nm, only. The effective charge transfer process with its larger off-site and on-site charging at intermediate states dominates tunnel transfer in STM, biology and chemistry over distances in the nm-range. Intermediates state tunneling becomes variable range hopping conduction for distances larger than d > 2 nm, for larger densities of intermediate states n 1 (ε) and for larger temperatures T or voltages U, still allowing high resolution imaging

One-Electron Theory of Metals. Cohesive and Structural Properties

DEFF Research Database (Denmark)

Skriver, Hans Lomholt

The work described in the report r.nd the 16 accompanying publications is based upon a one-electron theory obtained within the local approximation to density-functional theory, and deals with the ground state of metals as obtained from selfconsistent electronic-structure calculations performed...... by means of the Linear Muffin-Tin Orbital (LMTO) method. It has been the goal of the work to establish how well this one-electron approach describes physical properties such as the crystal structures of the transition metals, the structural phase transitions in the alkali, alkaline earth, and rare earth...

Structural, dynamic, electronic, and vibrational properties of flexible, intermediate, and stressed rigid As-Se glasses and liquids from first principles molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Bauchy, M. [Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095-1593 (United States); Kachmar, A. [Laboratoire de Physique Théorique de la Matière Condensée, Université Pierre et Marie Curie, 4 Place Jussieu, F-75252 Paris Cedex 05 (France); Qatar Environment and Energy Research Institute, Qatar Foundation, P.O. Box 5825, Doha (Qatar); Micoulaut, M., E-mail: mmi@lptl.jussieu.fr [Laboratoire de Physique Théorique de la Matière Condensée, Université Pierre et Marie Curie, 4 Place Jussieu, F-75252 Paris Cedex 05 (France)

2014-11-21

The structural, vibrational, electronic, and dynamic properties of amorphous and liquid As{sub x}Se{sub 1-x} (0.10 intermediate phase in these glassy networks, observed at 0.27 one derived from mean-field approaches of stiffness transitions.

Two-electron one-photon decay rates in doubly ionized atoms

International Nuclear Information System (INIS)

Baptista, G.B.

1984-01-01

The transion rate for the two-electron one-photon and one-electron one-photon decaying processes in atoms bearing initially two K-shell vacancies were evaluated for Ne up to Zr. The two-electron one-photon decay process is considered to be the result of the interaction between the jumping electrons and their interaction with the radiation field. The calculation is performed in second order perturbation theory and the many particle states are constructed from single particle solutions. The present approach allows one to discuss several aspects of the decaying process. The results obtained for the branching ratio between the two processes reproduces reasonably well available experimental data and show an almost linear dependence on the second power of the atomic number. A comparison with other theoretical predictions is also presented for the two decaying processes and the strong dependence of the branching ratio on the initial configuration of the decaying atom is pointed out. (Author) [pt

Excess electrons in reduced rutile and anatase TiO2

Science.gov (United States)

Yin, Wen-Jin; Wen, Bo; Zhou, Chuanyao; Selloni, Annabella; Liu, Li-Min

2018-05-01

As a prototypical photocatalyst, TiO2 is a material of scientific and technological interest. In photocatalysis and other applications, TiO2 is often reduced, behaving as an n-type semiconductor with unique physico-chemical properties. In this review, we summarize recent advances in the understanding of the fundamental properties and applications of excess electrons in reduced, undoped TiO2. We discuss the characteristics of excess electrons in the bulk and at the surface of rutile and anatase TiO2 focusing on their localization, spatial distribution, energy levels, and dynamical properties. We examine specific features of the electronic states for photoexcited TiO2, for intrinsic oxygen vacancy and Ti interstitial defects, and for surface hydroxyls. We discuss similarities and differences in the behaviors of excess electrons in the rutile and anatase phases. Finally, we consider the effect of excess electrons on the reactivity, focusing on the interaction between excess electrons and adsorbates.

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

Infrared behaviour of metallic systems in one, two and three dimensions

International Nuclear Information System (INIS)

Hinkelmann, H.

1976-01-01

A simple approximate expression for the electron lifetime tau(ω) in metals is rederived and discussed for different dimensions. In the 3D-case we get the well known Drude behaviour, i.e. a constant tau. In one dimension tau(ω) is strongly frequency-dependent in the IR. The 2D-case is intermediate to the preceding ones. These results are essentially due to the different form of the Fermi surface for an electron gas in one, two and three dimensions. (orig.) [de

New aspects about reduced LCF-life time of spherical ductile cast iron due to dynamic strain aging at intermediate temperatures

International Nuclear Information System (INIS)

Mouri, Hayato; Wunderlich, Wilfried; Hayashi, Morihito

2009-01-01

Spherical ductile cast iron (FCD400) is widely used as container material in nuclear energy processing line due to its superior mechanical properties and low price. Fatigue properties in low cycle fatigue (LCF) can be described well by the Manson-Coffin-Basquin's rule. However, at intermediate temperature range between 453 and 723 K the elongation-temperature-diagram shows a significantly 20-10% reduced elongation and an increase in yield stress in tensile test experiments. These non-linear deviations and the phenomenon of less ductility at intermediate temperatures are known for a long time [K. Chijiiwa, M. Hayashi, Mechanical properties of ductile cast iron at temperature in the region of room temperature to liquid, Imono 51 (7) (2004) 395-400]. But the following explanation is presented for the first time. In the same temperature range as the reduced fatigue life time dynamic strain ageing (DSA) also known as Portevin-le-Chartelier effect with the formation of visible serrations occurs. Both phenomena are explained by interaction effects between carbon diffusion and dislocation velocity which have at this temperature the same order of magnitude. However, this phenomenon shows interesting behavior at intermediate temperature range. During the low cycle fatigue test, DSA phenomenon disappeared, but mechanical properties show clear evidence of DSA phenomenon. Therefore, the purpose of this paper is to study the correlation of DSA occurrence, LCF and mechanical properties.

One-particle reducibility in effective scattering theory

International Nuclear Information System (INIS)

Vereshagin, V.

2016-01-01

To construct the reasonable renormalization scheme suitable for the effective theories one needs to resolve the “problem of couplings” because the number of free parameters in a theory should be finite. Otherwise the theory would loose its predictive power. In the case of effective theory already the first step on this way shows the necessity to solve the above-mentioned problem for the 1-loop 2-leg function traditionally called self energy. In contrast to the customary renormalizable models the corresponding Feynman graph demonstrates divergencies that require introducing of an infinite number of prescriptions. In the recent paper [1] it has been shown that the way out of this difficulty requires the revision of the notion of one-particle reducibility. The point is that in effective scattering theory one can introduce two different notions: the graphic reducibility and the analytic one. Below we explain the main ideas of the paper [1] and recall some notions and definitions introduced earlier in [2] and [3

Electronic Effects in the Cyclocondensation of Benzil

Indian Academy of Sciences (India)

IAS Admin

This is attributed to the reduced availability of the lone pair of electrons on nitrogen in urea that is needed for assisting the dehydration of the intermediate. Introduction. A popular experiment performed in MSc organic chemistry labo- ratory classes is the following sequence of simple preparations starting from benzaldehyde ...

Positivity of the spherically averaged atomic one-electron density

DEFF Research Database (Denmark)

Fournais, Søren; Hoffmann-Ostenhof, Maria; Hoffmann-Ostenhof, Thomas

2008-01-01

We investigate the positivity of the spherically averaged atomic one-electron density . For a which stems from a physical ground state we prove that for r ≥  0. This article may be reproduced in its entirety for non-commercial purposes.......We investigate the positivity of the spherically averaged atomic one-electron density . For a which stems from a physical ground state we prove that for r ≥  0. This article may be reproduced in its entirety for non-commercial purposes....

Electronic, Optical, and Thermal Properties of Reduced-Dimensional Semiconductors

Science.gov (United States)

Huang, Shouting

Reduced-dimensional materials have attracted tremendous attention because of their new physics and exotic properties, which are of great interests for fundamental science. More importantly, the manipulation and engineering of matter on an atomic scale yield promising applications for many fields including nanoelectronics, nanobiotechnology, environments, and renewable energy. Because of the unusual quantum confinement and enhanced surface effect of reduced-dimensional materials, traditional empirical models suffer from necessary but unreliable parameters extracted from previously-studied bulk materials. In this sense, quantitative, parameter-free approaches are highly useful for understanding properties of reduced-dimensional materials and, furthermore, predicting their novel applications. The first-principles density functional theory (DFT) is proven to be a reliable and convenient tool. In particular, recent progress in many-body perturbation theory (MBPT) makes it possible to calculate excited-state properties, e.g., quasiparticle (QP) band gap and optical excitations, by the first-principles approach based on DFT. Therefore, during my PhD study, I employed first-principles calculations based on DFT and MBPT to systematically study fundamental properties of typical reduced-dimensional semiconductors, i.e., the electronic structure, phonons, and optical excitations of core-shell nanowires (NWs) and graphene-like two-dimensional (2D) structures of current interests. First, I present first-principles studies on how to engineer band alignments of nano-sized radial heterojunctions, Si/Ge core-shell NWs. Our calculation reveals that band offsets in these one-dimensional (1D) nanostructures can be tailored by applying axial strain or varying core-shell sizes. In particular, the valence band offset can be efficiently tuned across a wide range and even be diminished via applied strain. Two mechanisms contribute to this tuning of band offsets. Furthermore, varying the

Treatment of low- and intermediate-level solid radioactive wastes

International Nuclear Information System (INIS)

1983-01-01

One of the essential aims in the waste management is to reduce as much as possible the waste volumes to be stored or disposed of, and to concentrate and immobilize as much as possible the radioactivity contained in the waste. This document describes the treatment of low- and intermediate-level solid waste prior to its conditioning for storage and disposal. This report aims primarily at compiling the experience gained in treating low- and intermediate-active solid wastes, one of the major waste sources in nuclear technology. Apart from the description of existing facilities and demonstrated handling schemes, this report provides the reader with the basis for a judgement that facilitates the selection of appropriate solutions for a given solid-waste management problem. It thus aims at providing guidelines in the particular field and indicates new promising approaches that are actually under investigation and development

Discourses and Models of Intermediality

OpenAIRE

Schröter, Jens

2011-01-01

In his article "Discourses and Models of Intermediality" Jens Schröter discusses the question as to what relations do different discourses pose between different "media." Schröter identifies four models of discourse: 1) synthetic intermediality: a "fusion" of different media to super-media, a model with roots in the Wagnerian concept of Gesamtkunstwerk with political connotations, 2) formal (or transmedial) intermediality: a concept based on formal structures not "specific" to one medium but ...

One-carbon 13C-labeled synthetic intermediates. Comparison and evaluation of preparative methods

International Nuclear Information System (INIS)

Ott, D.G.

1978-01-01

Frequently the biggest stumbling block to the synthesis of a structurally complex labeled compound is obtaining the required low molecular weight, structurally simple, isotopic intermediates. Selection of a particular scheme from various alternatives depends on the available capabilities and quantity of product desired, as well as on anticipated future requirements and need for related compounds. Many of the newer reagents for organic synthesis can be applied effectively to isotopic preparations with improvements of yields and simplification of procedures compared to established classical methods. New routes developed for higher molecular weight compounds are sometimes not directly adaptable to the one-carbon analogs, either because of isolation difficulties occasioned by physical properties or by chemical reactivities peculiar to their being first members of homologous series. Various routes for preparation of carbon-13 labeled methanol, formaldehyde, and cyanide are compared

Electronic prescribing reduces prescribing error in public hospitals.

Science.gov (United States)

Shawahna, Ramzi; Rahman, Nisar-Ur; Ahmad, Mahmood; Debray, Marcel; Yliperttula, Marjo; Declèves, Xavier

2011-11-01

To examine the incidence of prescribing errors in a main public hospital in Pakistan and to assess the impact of introducing electronic prescribing system on the reduction of their incidence. Medication errors are persistent in today's healthcare system. The impact of electronic prescribing on reducing errors has not been tested in developing world. Prospective review of medication and discharge medication charts before and after the introduction of an electronic inpatient record and prescribing system. Inpatient records (n = 3300) and 1100 discharge medication sheets were reviewed for prescribing errors before and after the installation of electronic prescribing system in 11 wards. Medications (13,328 and 14,064) were prescribed for inpatients, among which 3008 and 1147 prescribing errors were identified, giving an overall error rate of 22·6% and 8·2% throughout paper-based and electronic prescribing, respectively. Medications (2480 and 2790) were prescribed for discharge patients, among which 418 and 123 errors were detected, giving an overall error rate of 16·9% and 4·4% during paper-based and electronic prescribing, respectively. Electronic prescribing has a significant effect on the reduction of prescribing errors. Prescribing errors are commonplace in Pakistan public hospitals. The study evaluated the impact of introducing electronic inpatient records and electronic prescribing in the reduction of prescribing errors in a public hospital in Pakistan. © 2011 Blackwell Publishing Ltd.

One-particle reducible contribution to the one-loop spinor propagator in a constant field

Directory of Open Access Journals (Sweden)

N. Ahmadiniaz

2017-11-01

Full Text Available Extending work by Gies and Karbstein on the Euler–Heisenberg Lagrangian, it has recently been shown that the one-loop propagator of a charged scalar particle in a constant electromagnetic field has a one-particle reducible contribution in addition to the well-studied irreducible one. Here we further generalize this result to the spinor case, and find the same relation between the reducible term, the tree-level propagator and the one-loop Euler–Heisenberg Lagrangian as in the scalar case. Our demonstration uses a novel worldline path integral representation of the photon-dressed spinor propagator in a constant electromagnetic field background.

High heat flux testing of TiC coated molybdenum with a tungsten intermediate layer

International Nuclear Information System (INIS)

Fujitsuka, Masakazu; Fukutomi, Masao; Okada, Masatoshi

1988-01-01

The use of low atomic number (Z) material coatings for fusion reactor first-wall components has proved to be a valuable technique to reduce the plasma radiation losses. Molybdenum coated with titanium carbide is considered very promising since it has a good capability of receiving heat from the plasma. An interfacial reaction between the TiC film and the molybdenum substrate, however, causes a severe deterioration of the film at elevated temperatures. In order to solve this problem a TiC coated molybdenum with an intermediate tungsten layer was developed. High temperature properties of this material was evaluated by a newly devised electron beam heating apparatus. TiC coatings prepared on a vacuum-heat-treated molybdenum with a tungsten intermediate layer showed good high temperature stability and survived 2.0 s pulses of heating at a power density as high as 53 MW/m 2 . The melt area of the TiC coatings in high heat flux testings also markedly decreased when a tungsten intermediate layer was applied. The melting mechanism of the TiC coatings with and without a tungsten intermediate layer was discussed by EPMA measurements. (author)

The role of rotational mechanisms in electron swarm parameters at low reduced electric field in N2, O2 and H2

International Nuclear Information System (INIS)

Ridenti, M A; Amorim, J; Alves, L L; Guerra, V

2015-01-01

The homogeneous Boltzmann equation for electrons in N 2 , O 2 and H 2 is solved under the classical two-term approximation, for reduced electric fields in the interval 10   −  4   −10 Td where the electron-neutral encounters are limited to elastic, rotational and vibrational collisions. Rotational excitations/de-excitations are described using the following three different approaches: the discrete inelastic/superelastic collisional operator, written for a number of rotational levels that depends on the molecular gas and the specific rotational cross sections considered; the continuous approximation for rotations; a modified version of the continuous approximation for rotations, including a Chapman–Cowling corrective term proportional to the gas temperature. The expression of the rotational collision operator for this latter approach is deduced here and the results show that it bridges the gap between the discrete and the continuous descriptions at low/intermediate reduced electric fields. The calculations are compared with the measurements for the available swarm parameters to assess the validity of the different approaches and cross sections adopted to describe the rotational mechanisms. (paper)

Electronic Structure of the Ferryl Intermediate in the α-Ketoglutarate Dependent Non-Heme Iron Halogenase SyrB2: Contributions to H Atom Abstraction Reactivity

Czech Academy of Sciences Publication Activity Database

Srnec, Martin; Wong, S. D.; Matthews, M. L.; Krebs, C.; Bollinger, J. M.; Solomon, E. I.

2016-01-01

Roč. 138, č. 15 (2016), s. 5110-5122 ISSN 0002-7863 R&D Projects: GA ČR(CZ) GJ15-10279Y Institutional support: RVO:61388955 Keywords : Ferryl intermediate * syringomycin halogenase * electronic structure Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 13.858, year: 2016

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

Observation of Zero-Dimensional States in a One-Dimensional Electron Interferometer

NARCIS (Netherlands)

Wees, B.J. van; Kouwenhoven, L.P.; Harmans, C.J.P.M.; Williamson, J.G.; Timmering, C.E.; Broekaart, M.E.I.; Foxon, C.T.; Harris, J.J.

1989-01-01

We have studied the electron transport in a one-dimensional electron interferometer. It consists of a disk-shaped two-dimensional electron gas, to which quantum point contacts are attached. Discrete zero-dimensional states are formed due to constructive interference of electron waves traveling along

Interpretation of second Born amplitudes in electron capture

International Nuclear Information System (INIS)

McGuire, J.H.; Simony, P.R.; Weaver, O.L.; Macek, J.

1982-01-01

Exact sound Born amplitudes for 1s-1s electron capture are presented and interpreted in terms of contributions from intermediate states off the energy shell and on the energy shell. The classical model of Thomas corresponds to two-step scattering via one particular on-shell intermediate state. In the high-velocity limit for 1s-1s capture, this on-shell intermediate state of the Thomas model accounts for one-half of the total cross section, i.e., the second Born cross section. The other half comes from off-energy-shell intermediate states near the on-shell Thomas state. Above 5 MeV both the off-shell and on-shell amplitudes have a simple structure near the Thomas peak. Below 1 MeV, contributions from a broader range of intermediate states are evident in the amplitudes. Although the contribution from the Thomas state is not large below 1 MeV, other second Born effects are significant

The effect of six-point one-particle reducible local interactions in the dual fermion approach

International Nuclear Information System (INIS)

Katanin, A A

2013-01-01

We formulate the dual fermion approach for strongly correlated electronic systems in terms of the lattice and dual effective interactions, obtained by using the covariation splitting formula. This allows us to consider the effect of six-point one-particle reducible interactions, which are usually neglected by the dual fermion approach. We show that the consideration of one-particle reducible six-point (as well as higher order) vertices is crucially important for the diagrammatic consistency of this approach. In particular, the relation between the dual and lattice self-energy, derived in the dual fermion approach, implicitly accounts for the effect of the diagrams, containing six-point and higher order local one-particle reducible vertices, and should be applied with caution, if these vertices are neglected. Apart from that, the treatment of the self-energy feedback is also modified by six-point and higher order vertices; these vertices are also important to account for some non-local corrections to the lattice self-energy, which have the same order in the local four-point vertices as the diagrams usually considered in the approach. These observations highlight an importance of six-point and higher order vertices in the dual fermion approach, and call for the development of new schemes of treatment of non-local fluctuations, which are based on one-particle irreducible quantities. (paper)

Future possibilities with intermediate-energy neutron beams

International Nuclear Information System (INIS)

Brady, F.P.

1987-01-01

Future possibilities for using neutrons of intermediate energies (50 - 200 MeV) as a probe of the nucleus are discussed. Some of the recent thinking concerning a systematic approach for studying elastic and inelastic scattering of electrons and hadrons and the important role of medium- and intermediate-energy neutrons in such a programme is reviewed. The advantages of neutrons in this energy range over neutrons with lower energies and over intermediate-energy pions for determining nuclear-transition and ground state densities, and for distinguishing proton from neutron density (isovector sensitivity), are noted. The important role of (n,p) charge exchange reactions in nuclear excitation studies is also reviewed. Experimental methods for utilizing neutrons as probes in elastic, inelastic, and charge exchange studies at these energies are discussed

Statistical and dynamical aspects of intermediate energy nuclear collisions

International Nuclear Information System (INIS)

Ghetti, R.

1997-01-01

Studies of intermediate energy heavy ion reactions have revealed that the probability of emitting n-fragments is reducible to the probability of emitting a single fragment through the binomial distribution. The resulting one-fragment probability shows a dependence on the thermal energy that is characteristic of statistical decay. Similarly, the charge distributions associated with n-fragment emission are reducible to the one-fragment charge distribution, and thermal scaling is observed. The reducibility equation for the n-fragment charge distribution contains a quantity with a value that starts from zero, at low transverse energies, and saturates at high transverse energies. This evolution may signal a transition from a coexistence phase to a vapour phase. In the search for a signal of liquid-gas phase transition, the appearance of intermittency is reconsidered. Percolation calculations, as well as data analysis, indicate that an intermittent-like signal appears from classes of events that do not coincide with the critical one. 232 refs

Statistical and dynamical aspects of intermediate energy nuclear collisions

Energy Technology Data Exchange (ETDEWEB)

Ghetti, R.

1997-01-01

Studies of intermediate energy heavy ion reactions have revealed that the probability of emitting n-fragments is reducible to the probability of emitting a single fragment through the binomial distribution. The resulting one-fragment probability shows a dependence on the thermal energy that is characteristic of statistical decay. Similarly, the charge distributions associated with n-fragment emission are reducible to the one-fragment charge distribution, and thermal scaling is observed. The reducibility equation for the n-fragment charge distribution contains a quantity with a value that starts from zero, at low transverse energies, and saturates at high transverse energies. This evolution may signal a transition from a coexistence phase to a vapour phase. In the search for a signal of liquid-gas phase transition, the appearance of intermittency is reconsidered. Percolation calculations, as well as data analysis, indicate that an intermittent-like signal appears from classes of events that do not coincide with the critical one. 232 refs.

[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

To the theory of spin-charge separation in one-dimensional correlated electron systems

International Nuclear Information System (INIS)

Zvyagin, A.A.

2004-01-01

Spin-charge separation is considered to be one of the key properties that distinguish low-dimensional electron systems from others. Three-dimensional correlated electron systems are described by the Fermi liquid theory. There, low-energy excitations (quasiparticles) are reminiscent of noninteracting electrons: They carry charges -e and spins 1/2 . It is believed that for any one-dimensional correlated electron system, low-lying electron excitations carry either only spin and no charge, or only charge without spin. That is why recent experiments looked for such low-lying collective electron excitations, one of which carries only spin, and the other carries only charge. Here we show that despite the fact that for exactly solvable one-dimensional correlated electron models there exist excitations which carry only spin and only charge, in all these models with short-range interactions the low-energy physics is described by low-lying collective excitations, one of which carries both spin and charge

One electron-based smallest flexible logic cell

Science.gov (United States)

Kim, S. J.; Lee, J. J.; Kang, H. J.; Choi, J. B.; Yu, Y.-S.; Takahashi, Y.; Hasko, D. G.

2012-10-01

A one electron-based operating half-adder, the smallest arithmetic block, has been implemented on silicon-on-insulator structure whose basic element is a nanoscale single-electron transistor (SET) with two symmetrical side-wall gates. Grayscale contour plots of the resulting cell output voltages exhibit the Coulomb blockade-induced periodic alternating high/low features. Their voltage transfer characteristics display typical Sum and Carry-Out functions for binary, multi-valued (MV), and binary-MV mixed input voltages. Moreover, the half-adder function converts into a subtraction mode by adjusting control gates of the SET element. This flexible multi-valued cell provides an arithmetic block for the SET MV logic family of high density integration, operating with ultra-low power.

One-step synthesis of Pt-reduced graphene oxide composites based on high-energy radiation technique

International Nuclear Information System (INIS)

Liu, Xuqiang; Jiang, Shubin; Huang, Wei; Song, Hongtao

2014-01-01

In this paper, we introduce a novel 60 Co-ray-irradiation-based one-step synthesis method of Pt-reduced graphene oxide composites (Pt-RGO) in acid aqueous solution. The compositional distribution of the particles in the samples was characterized by transmission electron microscopy. The structure and composition of the nanocomposite has been determined with a scanning electron microscope (SEM) equipped with an energy dispersion X-ray (EDS) analyzer. Surface enhanced Raman scattering (SERS) of graphene deposited by the Pt nanoparticles were investigated with the 514.5 nm excitation. It was found that small-sized and highly-dispersed Pt nanoparticles could easily grow on the RGO surface under acidic conditions. In addition, the obtained homogeneous dispersions exhibit long-term stability, which will facilitate the production of homogeneous composites. (orig.)

Sequential reduction–oxidation for photocatalytic degradation of tetrabromobisphenol A: Kinetics and intermediates

International Nuclear Information System (INIS)

Guo, Yaoguang; Lou, Xiaoyi; Xiao, Dongxue; Xu, Lei; Wang, Zhaohui; Liu, Jianshe

2012-01-01

Highlights: ► Sequential photocatalytic reduction–oxidation degradation of TBBPA was firstly examined. ► Different atmospheres were found to have significant effect on debromination reaction. ► A possible sequential photocatalytic reduction–oxidation pathway was proposed. - Abstract: C-Br bond cleavage is considered as a key step to reduce their toxicities and increase degradation rates for most brominated organic pollutants. Here a sequential reduction/oxidation strategy (i.e. debromination followed by photocatalytic oxidation) for photocatalytic degradation of tetrabromobisphenol A (TBBPA), one of the most frequently used brominated flame retardants, was proposed on the basis of kinetic analysis and intermediates identification. The results demonstrated that the rates of debromination and even photodegradation of TBBPA strongly depended on the atmospheres, initial TBBPA concentrations, pH of the reaction solution, hydrogen donors, and electron acceptors. These kinetic data and byproducts identification obtained by GC–MS measurement indicated that reductive debromination reaction by photo-induced electrons dominated under N 2 -saturated condition, while oxidation reaction by photoexcited holes or hydroxyl radicals played a leading role when air was saturated. It also suggested that the reaction might be further optimized for pretreatment of TBBPA-contaminated wastewater by a two-stage reductive debromination/subsequent oxidative decomposition process in the UV-TiO 2 system by changing the reaction atmospheres.

Acoustic and electronic properties of one-dimensional quasicrystals

International Nuclear Information System (INIS)

Nori, F.; Rodriguez, J.P.

1986-01-01

We study the acoustic and electronic properties of one-dimensional quasicrystals. Both numerical (nonperturbative) and analytical (perturbative) results are shown. The phonon and electronic spectra exhibit a self-similar hierarchy of gaps and many localized states in the gaps. We study quasiperiodic structures with any number of layers and several types of boundary conditions. We discuss the connection between our phonon model and recent experiments on quasiperiodic GaAs-AlAs superlattices. We predict the existence of many gap states localized at the surfaces

Bonding mechanism of a yttrium iron garnet film on Si without the use of an intermediate layer

International Nuclear Information System (INIS)

Pantzas, Konstantinos; Patriarche, Gilles; Talneau, Anne; Youssef, Jamal Ben

2014-01-01

Direct bonding of yttrium iron garnet (YIG) on silicon without the use of an intermediate bonding layer is demonstrated and characterized using scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy. During the bonding experiment, the garnet is reduced in the presence of oxide-free silicon. As a result, a 5 nm thick SiO 2 /amorphous-YIG bilayer is formed and welds the garnet to silicon.

Intermediate algebra & analytic geometry

CERN Document Server

Gondin, William R

1967-01-01

Intermediate Algebra & Analytic Geometry Made Simple focuses on the principles, processes, calculations, and methodologies involved in intermediate algebra and analytic geometry. The publication first offers information on linear equations in two unknowns and variables, functions, and graphs. Discussions focus on graphic interpretations, explicit and implicit functions, first quadrant graphs, variables and functions, determinate and indeterminate systems, independent and dependent equations, and defective and redundant systems. The text then examines quadratic equations in one variable, system

Formation and decay of the intermediate quasistationary ion N-2 during charge exchange between fast H- ions and nitrogen molecules

International Nuclear Information System (INIS)

Kazanskii, A.K.

1984-01-01

The detachment of the electron from the H - ion during a collision with the nitrogen molecule at 1--6 keV occurs as a result of charge transfer to an unstable intermediate state of the molecular ion N - 2 and the subsequent decay of the ion. The formation process is described in the impulse approximation, and the motion of nuclei in the ion is treated quasiclassically. Expressions are obtained for the spectrum of emitted electrons and for the energy-loss spectrum of heavy particles. These expressions relate the spectra to the cross sections for the vibrational excitation of N 2 by electron impact. A convenient expression for the amplitude for the formation of the intermediate state is obtained in the ''boomerang'' model, and it is shown that one of the parameters, considered to be adjustable in traditional theory, can be calculated

Electron microscopy of intermediate filaments: teaming up with atomic force and confocal laser scanning microscopy.

Science.gov (United States)

Kreplak, Laurent; Richter, Karsten; Aebi, Ueli; Herrmann, Harald

2008-01-01

Intermediate filaments (IFs) were originally discovered and defined by electron microscopy in myoblasts. In the following it was demonstrated and confirmed that they constitute, in addition to microtubules and microfilaments, a third independent, general filament system in the cytoplasm of most metazoan cells. In contrast to the other two systems, IFs are present in cells in two principally distinct cytoskeletal forms: (i) extended and free-running filament arrays in the cytoplasm that are integrated into the cytoskeleton by associated proteins of the plakin type; and (ii) a membrane- and chromatin-bound thin 'lamina' of a more or less regular network of interconnected filaments made from nuclear IF proteins, the lamins, which differ in several important structural aspects from cytoplasmic IF proteins. In man, more than 65 genes code for distinct IF proteins that are expressed during embryogenesis in various routes of differentiation in a tightly controlled manner. IF proteins exhibit rather limited sequence identity implying that the different types of IFs have distinct biochemical properties. Hence, to characterize the structural properties of the various IFs, in vitro assembly regimes have been developed in combination with different visualization methods such as transmission electron microscopy of fixed and negatively stained samples as well as methods that do not use staining such as scanning transmission electron microscopy (STEM) and cryoelectron microscopy as well as atomic force microscopy. Moreover, with the generation of both IF-type specific antibodies and chimeras of fluorescent proteins and IF proteins, it has become possible to investigate the subcellular organization of IFs by correlative fluorescence and electron microscopic methods. The combination of these powerful methods should help to further develop our understanding of nuclear architecture, in particular how nuclear subcompartments are organized and in which way lamins are involved.

Low and intermediate radioactive waste management at OPG's western waste management facility

International Nuclear Information System (INIS)

Ellsworth, M.

2006-01-01

'Full text:' This paper will discuss low and intermediate level radioactive waste operations at Ontario Power Generation's Western Waste Management Facility. The facility has been in operation since 1974 and receives about 5000 - 7000 m 3 of low and intermediate level radioactive waste per year from Ontario's nuclear power plants. Low-level radioactive waste is received at the Waste Volume Reduction Building for possible volume reduction before it is placed into storage. Waste may be volume reduced by one of two methods at the WWMF, through either compaction or incineration. The Compactor is capable of reducing the volume of waste by a factor up to 5:1 for most waste. The Radioactive Incinerator is capable of volume reducing incinerable material by a factor up to 70:1. After processing, low-level waste is stored in above ground concrete warehouse-like structures called Low Level Storage Buildings. Low-level waste that cannot be volume reduced is placed into steel containers and stored in the Low Level Storage Buildings. Intermediate level waste is stored mainly in steel lined concrete storage structures. WWMF has both above ground and in-ground storage structures for intermediate level waste. Intermediate level waste consists primarily of resin and filters used to keep reactor water systems clean, and some used reactor core components. All low and intermediate level waste storage at the WWMF is considered interim storage and the material can be retrieved for future disposal or permanent storage. Current improvement initiatives include the installation of a new radioactive incinerator and a shredder/bagger. The new incinerator is a continuous feed system that is expected to achieve volume reduction rates up to 70:1, while incinerating higher volumes of waste than its predecessor. The shredder will break down large/bulky items into a form, which can be processed for further volume reduction. A Refurbishment Waste Storage Project is underway in anticipation of the

Soft electromagnetic bremsstrahlung in inelastic hadronic collisions at high and intermediate energies

International Nuclear Information System (INIS)

Rueckl, R.

1978-01-01

Electromagnetic bremsstrahlung in hadronic collisions was studied extensively at low and intermediate energies. It was found that the infrared divergent term of the cross section describes the data well up to surprisingly large photon energies. Using essentially the same soft photon approximation, production of low mass-low energy electron pairs via internal conversion of soft virtual bremsstrahlung accompanying the production of charged hadrons in hadron-hadron collisions at very high and intermediate energies. The resulting electron yields explain, at least in part, the direct electrons with small transverse momenta seen at the ISR, and are in no contradiction to the rates observed at LAMPF

Improved tribological properties of TiC with porous nanostructured TiO2 intermediate layer

International Nuclear Information System (INIS)

Shanaghi, Ali; Ahangarani, Shahrokh; Sabour Rouhaghdam, Ali Reza; Chu, Paul K.

2011-01-01

Highlights: ► The porous TiO 2 nanoparticle coating is deposited as an intermediate layer on steel. ► A homogenous and low friction TiC nanostructure coating is deposited by plasma CVD. ► Intermediate layer can be determined the nucleation and growth of the TiC coating. ► The porous interlayer improves the friction and wear of the TiC nanostructure coating. - Abstract: The mismatch in the thermal expansion coefficients between TiC coatings and steel substrates and residual stress in the TiC degrade the tribological properties. In this work, a porous nanostructured TiO 2 coating is deposited as an intermediate layer on hot-work steel (H 11 ) before final deposition of the TiC film. This intermediate layer is expected to reduce the interfacial energy, decreases the thermal mismatch between TiC and steel, and improves the tribological properties. Grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and pin-on-disk are used to study the structure as well as tribological properties such as friction, wear, and hardness. Our results reveal that the porous TiO 2 interlayer improves the friction, wear, hardness, and elastic modulus of the system.

Surface Intermediates on Metal Electrodes at High Temperature

DEFF Research Database (Denmark)

Zachau-Christiansen, Birgit; Jacobsen, Torben; Bay, Lasse

1997-01-01

The mechanisms widely suggested for the O2-reduc-tion or H2-oxidation SOFC reactions involve inter-mediate O/H species adsorbed on the electrode surface. The presence of these intermediates is investigated by linear sweep voltammetry. In airat moderate temperatures (500øC) Pt in contact with YSZ...

Interpretation and code generation based on intermediate languages

DEFF Research Database (Denmark)

Kornerup, Peter; Kristensen, Bent Bruun; Madsen, Ole Lehrmann

1980-01-01

The possibility of supporting high level languages through intermediate languages to be used for direct interpretation and as intermediate forms in compilers is investigated. An accomplished project in the construction of an interpreter and a code generator using one common intermediate form...

Novel electron gas systems

International Nuclear Information System (INIS)

Senatore, G.; Rapisarda, F.; Conti, S.

1998-01-01

We review recent progress on the physics of electrons in the bilayered electron gas, relevant to coupled quantum wells in GaAs/AIGaAs heterostructures. First we focus on the phase diagram of a symmetric bilayer at T = B = 0, obtained by diffusion Monte Carlo (DMC) simulations. It is found that inter-layer correlations stabilize crystalline structures at intermediate inter-layer separation, while favoring a liquid phase at smaller distance. Also, the available DMC evidence is in contrast with the recently (Hartree-Fock) predicted total charge transfer (TCT), whereby all the electron spontaneously jump in one layer. In fact, one can show that such a TCT state is never stable in the ideal bilayer with no tunneling. We finally comment on ongoing DMC investigations on the electron-hole bilayer, where excitonic condensation is expected to take place. (Copyright (1998) World Scientific Publishing Co. Pte. Ltd)

Thin-film intermediate band chalcopyrite solar cells

International Nuclear Information System (INIS)

Fuertes Marron, D.; Marti, A.; Luque, A.

2009-01-01

Chalcopyrite-based solar cells currently lead the efficiency tables of thin-film photovoltaic technologies. Further improvements are foreseen upon implementation of an intermediate band in the absorber layers. We present a theoretical analysis of the efficiency limit for this type of device as a function of factors such as the gap of the host, the relative position of the intermediate band with respect to the band edge and the level of light concentration used as illumination. We have also considered the impact of non-idealities on the performance of the device, particularly the effect of electronic losses related to non-radiative recombination

Bridge mediated two-electron transfer reactions: Analysis of stepwise and concerted pathways

International Nuclear Information System (INIS)

Petrov, E.G.; May, V.

2004-01-01

A theory of nonadiabatic donor (D)-acceptor (A) two-electron transfer (TET) mediated by a single regular bridge (B) is developed. The presence of different intermediate two-electron states connecting the reactant state D -- BA with the product state DBA -- results in complex multiexponential kinetics. The conditions are discussed at which a reduction to two-exponential as well as single-exponential kinetics becomes possible. For the latter case the rate K TET is calculated, which describes the bridge-mediated reaction as an effective two-electron D-A transfer. In the limit of small populations of the intermediate TET states D - B - A, DB -- A, D - BA - , and DB - A - , K TET is obtained as a sum of the rates K TET (step) and K TET (sup) . The first rate describes stepwise TET originated by transitions of a single electron. It starts at D -- BA and reaches DBA -- via the intermediate state D - BA - . These transitions cover contributions from sequential as well as superexchange reactions all including reduced bridge states. In contrast, a specific two-electron superexchange mechanism from D -- BA to DBA -- defines K TET (sup) . An analytic dependence of K TET (step) and K TET (sup) on the number of bridging units is presented and different regimes of D-A TET are studied

The MHD intermediate shock interaction with an intermediate wave: Are intermediate shocks physical?

International Nuclear Information System (INIS)

Wu, C.C.

1988-01-01

Contrary to the usual belief that MHD intermediate shocks are extraneous, the authors have recently shown by numerical solutions of dissipative MHD equations that intermediate shocks are admissible and can be formed through nonlinear steepening from a continuous wave. In this paper, he clarifies the differences between the conventional view and the results by studying the interaction of an MHD intermediate shock with an intermediate wave. The study reaffirms his results. In addition, the study shows that there exists a larger class of shocklike solutions in the time-dependent dissiaptive MHD equations than are given by the MHD Rankine-Hugoniot relations. it also suggests a mechanism for forming rotational discontinuities through the interaction of an intermediate shock with an intermediate wave. The results are of importance not only to the MHD shock theory but also to studies such as magnetic field reconnection models

Hyperpolarizabilities of one and two electron ions under strongly coupled plasma

International Nuclear Information System (INIS)

Sen, Subhrangsu; Mandal, Puspajit; Kumar Mukherjee, Prasanta; Fricke, Burkhard

2013-01-01

Systematic investigations on the hyperpolarizabilities of hydrogen and helium like ions up to nuclear charge Z = 7 under strongly coupled plasma environment have been performed. Variation perturbation theory has been adopted to evaluate such properties for the one and two electron systems. For the two electron systems coupled Hartree-Fock theory, which takes care of partial electron correlation effects, has been utilised. Ion sphere model of the strongly coupled plasma, valid for ionic systems only, has been adopted for estimating the effect of plasma environment on the hyperpolarizability. The calculated free ion hyperpolarizability for all the systems is in good agreement with the existing data. Under confinement hyperpolarizabilities of one and two electron ions show interesting trend with respect to plasma coupling strength.

Determination of one-electron reduction potentials of some radiosensitive compounds by pulse radiolysis

International Nuclear Information System (INIS)

Zuo Zhihua; Yao Side; Li Hucheng; Lin Nianyun; Jin Yizun

1994-01-01

One-electron reduction potential (E 7 1 ) is one of the important parameters of radiosensitive compound with high electron affinity. In this work one-electron reduction potentials of some radiosensitizers, such as Miso, 911, CMNa, SMU-1, SMU-2, SMD, SNN, S 3 and BSO, were determined pulse radiolytically by using anthraquinone-2-sulfate (AQS), duroquinone (DQ) and methyl viologen (MV 2+ ) as references

Quasi-one-dimensional electron transport over the surface of a liquid-helium film

International Nuclear Information System (INIS)

Sokolov, Sviatoslav; Studart, Nelson

2003-01-01

Quasi-one-dimensional mobility of surface electrons over a liquid-helium suspended film is studied for a conducting channel. The electron mobility is calculated taking into account the electron scattering by helium atoms in the vapor phase, ripplons, and surface defects of the film substrate both in one-electron regime and in the so-called complete-control limit where the influence of inter-electron collisions on the electron distribution function is taken into account. It is shown that the mobility for low temperatures is dominated by the surface-defect scattering and its temperature dependence is essentially different from that of the electron-ripplon scattering

One-electron oxidation of DNA: mechanism and consequences.

Science.gov (United States)

Schuster, Gary B

2009-01-01

All living organisms store the information necessary to maintain life in their DNA. Any process that damages DNA and causes loss or corruption of that information threatens the viability of the organism. One-electron oxidation is such a process. Loss of an electron from DNA generates a radical cation that is located primarily on its nucleobases. The radical cation migrates reversibly through duplex DNA by hopping until it is eventually trapped in an irreversible chemical reaction. The particular sequence of nucleobases in a DNA oligomer determines both the efficiency of hopping and the specific location and nature of the damaging chemical reaction. In its normal aqueous solutions, DNA is a polyanion because of the negative charge carried by its phosphate groups. Counter ions (typically Na(+)) to the phosphate groups play an important role in facilitating both the migration of the radical cation and in its eventual reaction with H(2)O. Irreversible reaction of a radical cation with H(2)O in duplex DNA occurs preferentially at the most reactive site. In normal DNA that is comprised of the four common DNA nucleobases, reaction occurs most commonly at a guanine and results in its conversion primarily to 8-oxo-7,8-dihydroguanine (8-OxoG). Both electronic and steric effects control the outcome of this process. If the DNA oligomer does not contain a suitable guanine, then reaction of the radical cation occurs at the thymine of a TT step primarily by a tandem process. The general outcomes revealed in the one-electron oxidation of DNA oligomers in solution appear to be generally valid also for more complex DNA structures and for the cellular DNA of living organisms.

One-loop infinities in dimensionally reduced supergravities

International Nuclear Information System (INIS)

Fradkin, E.S.; Tseytlin, A.A.

1983-11-01

It is proved explicitly in the paper that d=4 theory following via reduction from N=1, d=10 supergravities is not finite at one loop while the version of N=8 supergravity directly following from N=1, d=11 theory is one-loop finite. The method used is based on quantization of initial higher dimensional theory as a first step. The results also suggest possible existence of non-standard (higher N) d>4 supergravities which reduce to d=4 theories with finite N=8 supergravity sector. (author)

Low temperature characterization of the photocurrent produced by two-photon transitions in a quantum dot intermediate band solar cell

International Nuclear Information System (INIS)

Antolin, E.; Marti, A.; Stanley, C.R.; Farmer, C.D.; Canovas, E.; Lopez, N.; Linares, P.G.; Luque, A.

2008-01-01

Conceived to exceed the conversion efficiency of conventional photovoltaic devices, the intermediate band solar cell bases its operation on exploiting, besides the usual band-to-band optical transitions, the absorption of two sub-bandgap photons. For the present, the only technology used to implement an intermediate band in real devices has been the growth of an InAs/GaAs quantum dot superlattice. In practice, the obtained material shows two limitations: the narrow energy gap between conduction and intermediate band and the appearance of growth defects due to the lattice stress. The consequences are the presence of non-radiative recombination mechanisms and the thermal escape of electrons from the intermediate to the conduction band, hindering the splitting of the quasi-Fermi levels associated with the intermediate and conduction bands and the observation of photocurrent associated with the two-photon absorption. By reducing the temperature at which the devices are characterised we have suppressed the parasitic thermal mechanisms and have succeeded in measuring the photocurrent caused by the absorption of two below bandgap photons. In this work, the characterization of this photocurrent at low temperature is presented and discussed

Warfarin traps human vitamin K epoxide reductase in an intermediate state during electron transfer

Science.gov (United States)

Shen, Guomin; Cui, Weidong; Zhang, Hao; Zhou, Fengbo; Huang, Wei; Liu, Qian; Yang, Yihu; Li, Shuang; Bowman, Gregory R.; Sadler, J. Evan; Gross, Michael L.; Li, Weikai

2017-01-01

Although warfarin is the most widely used anticoagulant worldwide, the mechanism by which warfarin inhibits its target, human vitamin K epoxide reductase (hVKOR), remains unclear. Here we show that warfarin blocks a dynamic electron-transfer process in hVKOR. A major fraction of cellular hVKOR is at an intermediate redox state of this process containing a Cys51-Cys132 disulfide, a characteristic accommodated by a four-transmembrane-helix structure of hVKOR. Warfarin selectively inhibits this major cellular form of hVKOR, whereas disruption of the Cys51-Cys132 disulfide impairs warfarin binding and causes warfarin resistance. Relying on binding interactions identified by cysteine alkylation footprinting and mass spectrometry coupled with mutagenesis analysis, we are able to conduct structure simulations to reveal a closed warfarin-binding pocket stabilized by the Cys51-Cys132 linkage. Understanding the selective warfarin inhibition of a specific redox state of hVKOR should enable the rational design of drugs that exploit the redox chemistry and associated conformational changes in hVKOR. PMID:27918545

Treatment of rod shaped intermediate active waste

International Nuclear Information System (INIS)

Graf, A.; Blase, F.; Dirks, F.; Valencia, L.

2002-01-01

The Central Decontamination Operation Department (HDB) of the Research Center Karlsruhe operates facilities for the disposal of radioactive waste. In general, their objective is to reduce the volume of the radioactive waste and to obtain waste products suitable for repository storage. One of the central facilities of the HDB is the intermediate level waste (ILW) scrapping facility which processes intermediate level waste. Since the ILW scrapping facility was not large enough to handle radioactive waste coming from the dismantling and operating of nuclear facilities, HDB expanded and built a larger hot cell. It contains a hydraulically driven metal cutter with a guiding channel and a high pressure compactor. A major task in the hot cell of the ILW scrapping facility is disposing of fuel boxes. These are cut in pieces and scrapped, which is a unique technique in Germany for fuel box disposal. HDB's experiences in disposing of radioactive waste in the ILW scrapping facility will described in detail, with special emphasis on the handling of rod shaped components. (author)

N-representability-driven reconstruction of the two-electron reduced-density matrix for a real-time time-dependent electronic structure method

International Nuclear Information System (INIS)

Jeffcoat, David B.; DePrince, A. Eugene

2014-01-01

Propagating the equations of motion (EOM) for the one-electron reduced-density matrix (1-RDM) requires knowledge of the corresponding two-electron RDM (2-RDM). We show that the indeterminacy of this expression can be removed through a constrained optimization that resembles the variational optimization of the ground-state 2-RDM subject to a set of known N-representability conditions. Electronic excitation energies can then be obtained by propagating the EOM for the 1-RDM and following the dipole moment after the system interacts with an oscillating external electric field. For simple systems with well-separated excited states whose symmetry differs from that of the ground state, excitation energies obtained from this method are comparable to those obtained from full configuration interaction computations. Although the optimized 2-RDM satisfies necessary N-representability conditions, the procedure cannot guarantee a unique mapping from the 1-RDM to the 2-RDM. This deficiency is evident in the mean-field-quality description of transitions to states of the same symmetry as the ground state, as well as in the inability of the method to describe Rabi oscillations

N-representability-driven reconstruction of the two-electron reduced-density matrix for a real-time time-dependent electronic structure method

Science.gov (United States)

Jeffcoat, David B.; DePrince, A. Eugene

2014-12-01

Propagating the equations of motion (EOM) for the one-electron reduced-density matrix (1-RDM) requires knowledge of the corresponding two-electron RDM (2-RDM). We show that the indeterminacy of this expression can be removed through a constrained optimization that resembles the variational optimization of the ground-state 2-RDM subject to a set of known N-representability conditions. Electronic excitation energies can then be obtained by propagating the EOM for the 1-RDM and following the dipole moment after the system interacts with an oscillating external electric field. For simple systems with well-separated excited states whose symmetry differs from that of the ground state, excitation energies obtained from this method are comparable to those obtained from full configuration interaction computations. Although the optimized 2-RDM satisfies necessary N-representability conditions, the procedure cannot guarantee a unique mapping from the 1-RDM to the 2-RDM. This deficiency is evident in the mean-field-quality description of transitions to states of the same symmetry as the ground state, as well as in the inability of the method to describe Rabi oscillations.

Thomson scattering on argon surfatron plasmas at intermediate pressures: Axial profiles of the electron temperature and electron density

Energy Technology Data Exchange (ETDEWEB)

Palomares, J.M., E-mail: f02palij@gmail.co [Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain); Iordanova, E.; Veldhuizen, E.M. van; Baede, L. [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Gamero, A.; Sola, A. [Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain); Mullen, J.J.A.M. van der, E-mail: j.j.a.m.v.d.Mullen@tue.n [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain)

2010-03-15

The axial profiles of the electron density n{sub e} and electron temperature T{sub e} of argon surfatron plasmas in the pressure range of 6-20 mbar and microwave power between 32 and 82 W have been determined using Thomson Scattering of laser irradiation at 532 nm. For the electron density and temperature we found values in the ranges 5 x 10{sup 18} < n{sub e} < 8 x 10{sup 19} m{sup -3} and 1.1 < T{sub e} < 2.0 eV. Due to several improvements of the setup we could reduce the errors of n{sub e} and T{sub e} down to 8% and 3%, respectively. It is found that n{sub e} decreases in the direction of the wave propagation with a slope that is nearly constant. The slope depends on the pressure but not on the power. Just as predicted by theories we see that increasing the power leads to longer plasma columns. However, the plasmas are shorter than what is predicted by theories based on the assumption that for the plasma-wave interaction electron-atom collisions are of minor importance (the so-called collisionless regime). The plasma vanishes long before the critical value of the electron density is reached. In contrast to what is predicted by the positive column model it is found that T{sub e} does not stay constant along the column, but monotonically increases with the distance from the microwave launcher. Increases of more than 50% over 30 cm were found.

Intermediate Bandgap Solar Cells From Nanostructured Silicon

Energy Technology Data Exchange (ETDEWEB)

Black, Marcie [Bandgap Engineering, Lincoln, MA (United States)

2014-10-30

This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

In situ one-pot preparation of reduced graphene oxide/polyaniline composite for high-performance electrochemical capacitors

International Nuclear Information System (INIS)

Chen, Nali; Ren, Yapeng; Kong, Peipei; Tan, Lin; Feng, Huixia; Luo, Yongchun

2017-01-01

Highlights: • A new method to prepare reduced graphene oxide/polyaniline composite is developed. • Aniline serves as a reduction for graphene oxide under weak alkali condition. • Different characterizations confirm that GO can be effectively reduced by aniline. • A high specific capacitance of 524.4 F·g"−"1 is obtained at 0.5 A·g"−"1. - Abstract: Reduced graphene oxide/polyaniline (rGO/PANI) composites are prepared through an effective in situ one-pot synthesis route that includes the reduction of graphene oxide (GO) by aniline under weak alkali condition via hydrothermal method and then followed by in situ polymerization of aniline. X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope are employed to reveal that GO is successfully reduced by aniline under weak alkali condition and PANI can be deposited on the surfaces of reduced graphene oxide (rGO) sheets. The effect of rGO is optimized by tuning the mass ratios of aniline to GO to improve the electrochemical performance of rGO/PANI composites. The maximum specific capacitance of rGO/PANI composites achieves 524.4 F/g with a mass ratio of aniline to GO 10:1 at a current density of 0.5 A/g, in comparison to the specific capacitance of 397 F/g at the same current density of pure PANI. Particularly, the specific capacity retention rate is 81.1% after 2000 cycles at 100 mv/s scan rate, which is an improvement over that of pure PANI (55.5%).

In situ one-pot preparation of reduced graphene oxide/polyaniline composite for high-performance electrochemical capacitors

Energy Technology Data Exchange (ETDEWEB)

Chen, Nali [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, Gansu (China); State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, Gansu (China); Ren, Yapeng; Kong, Peipei; Tan, Lin [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, Gansu (China); Feng, Huixia, E-mail: fenghx@lut.cn [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, Gansu (China); Luo, Yongchun, E-mail: luoyc@lut.cn [State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, Gansu (China)

2017-01-15

Highlights: • A new method to prepare reduced graphene oxide/polyaniline composite is developed. • Aniline serves as a reduction for graphene oxide under weak alkali condition. • Different characterizations confirm that GO can be effectively reduced by aniline. • A high specific capacitance of 524.4 F·g{sup −1} is obtained at 0.5 A·g{sup −1}. - Abstract: Reduced graphene oxide/polyaniline (rGO/PANI) composites are prepared through an effective in situ one-pot synthesis route that includes the reduction of graphene oxide (GO) by aniline under weak alkali condition via hydrothermal method and then followed by in situ polymerization of aniline. X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope are employed to reveal that GO is successfully reduced by aniline under weak alkali condition and PANI can be deposited on the surfaces of reduced graphene oxide (rGO) sheets. The effect of rGO is optimized by tuning the mass ratios of aniline to GO to improve the electrochemical performance of rGO/PANI composites. The maximum specific capacitance of rGO/PANI composites achieves 524.4 F/g with a mass ratio of aniline to GO 10:1 at a current density of 0.5 A/g, in comparison to the specific capacitance of 397 F/g at the same current density of pure PANI. Particularly, the specific capacity retention rate is 81.1% after 2000 cycles at 100 mv/s scan rate, which is an improvement over that of pure PANI (55.5%).

Adolescents' Use of Basic, Intermediate, and Advanced Device Types for Vaping.

Science.gov (United States)

Pepper, Jessica K; MacMonegle, Anna J; Nonnemaker, James M

2017-12-23

Advanced models of electronic vaping products (EVPs) likely pose a greater risk to adolescent health than basic or intermediate models because advanced models deliver nicotine more effectively and heat e-liquid to higher temperatures, producing more harmful chemical emissions. However, little is known about adolescents' risk factors for using different device types. We used social media to recruit an online sample of 1,508 U.S. adolescents aged 15-17 who reported past 30-day use of e-cigarettes. We assessed tobacco use, beliefs and knowledge about EVPs, and EVP use behavior, including the device type participants use most frequently. We used multinomial logistic regression to examine differences between adolescents who usually use intermediate versus basic and advanced versus basic devices. Most respondents usually used modifiable advanced devices (56.8%) rather than basic "cigalike" (14.5%) or pen-style intermediate (28.7%) devices. Use of multiple device types was common, particularly among those who primarily used basic devices. Younger age and less frequent vaping were associated with mainly using basic devices. Adolescents who were older, male, personally bought their main device, and had ever mixed e-liquids were at elevated risk for usually using advanced devices. Adolescents who primarily use basic devices may be newer users who are experimenting with multiple devices. Future research should examine which adolescents are most likely to transition to advanced devices in order to develop targeted interventions. Regulators should consider strategies to reduce access to all types of EVPs, such as better enforcement of the current ban on sales to minors. This research addresses two gaps in research on adolescent electronic vaping product use: (1) characterizing use of advanced devices as distinct from intermediate devices rather than grouping them together and (2) examining factors associated with use of specific device types. This study suggests that there

I. Exchange currents in electron scattering from light nuclei. II. Heavy-ion scattering at intermediate and high energy

International Nuclear Information System (INIS)

Dubach, J.F.

1976-01-01

The purpose of this work is to develop a formalism that will allow one to search the wide variety of transitions presented by nuclei in order to locate situations in which the exchange-current effects are important or dominant and thus allow one to study the contributions of the meson exchanges to the electromagnetic densities within the nucleus. The nuclei studied are assumed to be described in a shell model using harmonic oscillator wave functions. The formalism needed to allow one to do a multipole analysis of these exchange currents within 1s and 1p nuclei is developed. This formalism is then applied to an examination of electron scattering from a series of light nuclei: 3 He, 6 Li, 7 Li, 9 Be, and 10 B. Three significant effects due to the inclusion of exchange currents are seen: (1) The exchange currents can often introduce new structure into the form factors. (2) At larger momentum transfer (700 to 1000 MeV/c) the exchange current contributions to the form factor dominate the simpler one-body form factor by a few orders of magnitude. (3) The exchange currents can excite E4 and M5 multipoles in the p shell which are forbidden to the simpler one-body currents. The elastic scattering of two heavy ions at intermediate and high energies (compared to the Coulomb barrier) is examined in the formalism of the WKB and ''Glauber theory'' approximations. As a concrete example, the scattering of 16 O from 60 Ni is studied assuming an optical-model potential that fits elastic scattering data at low energies. One immediate result is that the WKB approximation agrees quite well with ''exact'' numerical calculations at energies as low as 60 MeV. The Glauber theory fails below about 1 GeV but correction terms are developed that can extend the usefulness of the Glauber theory to much lower energies. The model problem of scattering from a black-sphere model of the nucleus is briefly examined

Larval helminths in intermediate hosts

DEFF Research Database (Denmark)

Fredensborg, Brian Lund; Poulin, R

2005-01-01

Density-dependent effects on parasite fitness have been documented from adult helminths in their definitive hosts. There have, however, been no studies on the cost of sharing an intermediate host with other parasites in terms of reduced adult parasite fecundity. Even if larval parasites suffer a ...

Scatter correction, intermediate view estimation and dose characterization in megavoltage cone-beam CT imaging

Science.gov (United States)

Sramek, Benjamin Koerner

The ability to deliver conformal dose distributions in radiation therapy through intensity modulation and the potential for tumor dose escalation to improve treatment outcome has necessitated an increase in localization accuracy of inter- and intra-fractional patient geometry. Megavoltage cone-beam CT imaging using the treatment beam and onboard electronic portal imaging device is one option currently being studied for implementation in image-guided radiation therapy. However, routine clinical use is predicated upon continued improvements in image quality and patient dose delivered during acquisition. The formal statement of hypothesis for this investigation was that the conformity of planned to delivered dose distributions in image-guided radiation therapy could be further enhanced through the application of kilovoltage scatter correction and intermediate view estimation techniques to megavoltage cone-beam CT imaging, and that normalized dose measurements could be acquired and inter-compared between multiple imaging geometries. The specific aims of this investigation were to: (1) incorporate the Feldkamp, Davis and Kress filtered backprojection algorithm into a program to reconstruct a voxelized linear attenuation coefficient dataset from a set of acquired megavoltage cone-beam CT projections, (2) characterize the effects on megavoltage cone-beam CT image quality resulting from the application of Intermediate View Interpolation and Intermediate View Reprojection techniques to limited-projection datasets, (3) incorporate the Scatter and Primary Estimation from Collimator Shadows (SPECS) algorithm into megavoltage cone-beam CT image reconstruction and determine the set of SPECS parameters which maximize image quality and quantitative accuracy, and (4) evaluate the normalized axial dose distributions received during megavoltage cone-beam CT image acquisition using radiochromic film and thermoluminescent dosimeter measurements in anthropomorphic pelvic and head and

Pulse radiolytic one-electron reduction of 1,4-amino and hydroxy disubstituted 9,10-anthraquinones

International Nuclear Information System (INIS)

Pal, H.; Palit, D.K.; Mukherjee, T.; Mittal, J.P.

1992-01-01

The semiquinone radicals produced by one-electron reduction of 1-amino-4-hydroxy-9,10-anthraquinone and 1,4-diamino-9,10-anthraquinone have been studied in aqueous-organic mixed solvent using pulse radiolysis technique. Spectroscopic characteristics, kinetic characteristics of formation and decay, acid/base behaviour and redox characteristics of the semiquinones have been investigated and compared with those of some similar systems studied earlier. It has been shown that the variation of the disproportionation equilibria involving the reduced semiquinone radicals, the parent quinone and the fully reduced hydroquinone with pH of the solutions follow a similar trend as observed in the case of other dihydroxy quinones. Stability of the semiquinones over a broad pH range and their thermodynamic properties have been correlated. (Author)

Visualizing One-Dimensional Electronic States and their Scattering in Semi-conducting Nanowires

Science.gov (United States)

Beidenkopf, Haim; Reiner, Jonathan; Norris, Andrew; Nayak, Abhay Kumar; Avraham, Nurit; Shtrikman, Hadas

One-dimensional electronic systems constitute a fascinating playground for the emergence of exotic electronic effects and phases, within and beyond the Tomonaga-Luttinger liquid paradigm. More recently topological superconductivity and Majorana modes were added to that long list of phenomena. We report scanning tunneling microscopy and spectroscopy measurements conducted on pristine, epitaxialy grown InAs nanowires. We resolve the 1D electronic band structure manifested both via Van-Hove singularities in the local density-of-states, as well as by the quasi-particle interference patterns, induced by scattering from surface impurities. By studying the scattering of the one-dimensional electronic states off various scatterers, including crystallographic defects and the nanowire end, we identify new one-dimensional relaxation regimes and yet unexplored effects of interactions. Some of these may bear implications on the topological superconducting state and Majorana modes therein. The authors acknowledge support from the Israeli Science Foundation (ISF).

Search for intermediate vector bosons

International Nuclear Information System (INIS)

Klajn, D.B.; Rubbia, K.; Meer, S.

1983-01-01

Problem of registration and search for intermediate vector bosons is discussed. According to weak-current theory there are three intermediate vector bosons with +1(W + )-1(W - ) and zero (Z 0 ) electric charges. It was suggested to conduct the investigation into particles in 1976 by cline, Rubbia and Makintair using proton-antiproton beams. Major difficulties of the experiment are related to the necessity of formation of sufficient amount of antiparticles and the method of antiproton beam ''cooling'' for the purpose of reduction of its random movements. The stochastic method was suggested by van der Meer in 1968 as one of possible cooling methods. Several large detectors were designed for searching intermediate vector bosons

Electronic excitation of Na atom by electron impact

International Nuclear Information System (INIS)

Bielschowsky, C.E.; Souza, G.G.B. de; Lucas, C.A.; Nogueira, J.C.

1988-01-01

Electronic excitation of the 3s-3p transition in the Na atom was studied by intermediate energy electron impact spectroscopy. Differential Cross Sections (DCS) and Generalized Oscillator Strenghts (GOS) were determined experimentally for 1 KeV electrons. Theoretical results within the First Born Approximation as well as Glauber theory, were also performed. (A.C.A.S.) [pt

Higher order antibunching in intermediate states

International Nuclear Information System (INIS)

Verma, Amit; Sharma, Navneet K.; Pathak, Anirban

2008-01-01

Since the introduction of binomial state as an intermediate state, different intermediate states have been proposed. Different nonclassical effects have also been reported in these intermediate states. But till now higher order antibunching is predicted in only one type of intermediate state, which is known as shadowed negative binomial state. Recently we have shown that the higher order antibunching is not a rare phenomenon [P. Gupta, P. Pandey, A. Pathak, J. Phys. B 39 (2006) 1137]. To establish our earlier claim further, here we have shown that the higher order antibunching can be seen in different intermediate states, such as binomial state, reciprocal binomial state, hypergeometric state, generalized binomial state, negative binomial state and photon added coherent state. We have studied the possibility of observing the higher order subpoissonian photon statistics in different limits of intermediate states. The effects of different control parameters on the depth of non classicality have also been studied in this connection and it has been shown that the depth of nonclassicality can be tuned by controlling various physical parameters

Prediction of isotope effects for anticipated intermediate structures in the course of bacterial denitrification

International Nuclear Information System (INIS)

Morgenstern, M.A.; Schowen, R.L.

1989-01-01

Vibrational-analysis methods have been used to estimate the equilibrium 14 N/ 15 N isotope effects to be expected for conversion of nitrite anion to thirteen possible intermediate-state and product-state structures [HONO, NO + , NO, NO - , FeNO, ON * NO 2 , O * NNO 2 , O 2 NNO 2 , ONO * N, O * NON, ONNO, * NNO, N * NO] in the reduction of nitrite ion to nitrous oxide denitrifying bacteria. The results, taken in combination with previous experimental isotope-effect and tracer studies of the Pseudomonas stutzeri and related systems, are consistent with a suggestion that a second nitrite anion enters the enzyme-catalytic cycle at the stage of a nitrosyl-ion intermediate but re-emerges after entry of the reducing electrons; the product nitrous oxide is then formed by disproportionation of enzymically generated hyponitrous acid. The calculations are consistent with contributions, under different experimental conditions, of several different transition states to limiting the rate of the enzymic reaction. These transition states (and the corresponding experimental conditions) are the transition states for N-O fission in the generation of a mononitrogen electrophilic species from nitrite anion (high reductant, high nitrite concentrations), for attack of nitrite on this electrophile (high reductant, low nitrite concentrations) and for electron transfer to a dinitrogen-trioxide-like species (low reductant concentration). (orig.)

About the structure of quantum intermediate state of superconductors

International Nuclear Information System (INIS)

Ledenev, O.P.

2008-01-01

The calculation of spatial structure of a quantum intermediate state in Type I superconductors is completed. Theoretical model of thermodynamics of considered state was proposed by Andreev. It is shown, that in a quantum case, the period of structure appears significantly smaller and has different dependence on both the magnetic field and temperature than in the classical intermediate Landau state. The decrease of thickness of normal layers results in increase of characteristic distance between the quantum Andreev levels of electronic excitations, and the transition to the quantum intermediate from classical state is realized at higher temperatures ∼1 K, than it was supposed in previous works. The comparison of calculation data with experimental results, for example using the sample of mono-crystal gallium, is conducted

Magnetotransport in a quasi-one-dimensional electron system over superfluid helium

CERN Document Server

Nikolaenko, V A; Gladchenko, S P

2002-01-01

Magnetotransport in a nondegenerate quasi-one-dimensional electron system (Q1D) over superfluid helium is investigated experimentally. The experiments were carried out at perpendicular magnetic fields, B 0.9 K) and the electron-ripplon scattering (T 1(here omega sub c is the cyclotron frequency and t is the relaxation time of the electron system) agree qualitatively with the self-consistent Born approximation theory for a 2D electron system over helium. It is supposed that the quantitative discrepancies in the experimental and theoretical data are connected with different peculiar features of the investigated and analyzed electron systems. The experimental data on electron mobility at low temperatures and small magnetic fields coincide with the theoretical calculation made for the Q1D system. The negative magnetoresistance of the channels observed both in the electron-gas scattering and electron-ripplon scattering regions is supposed to be due to weak localization of carriers in the investigated electron syst...

Theory of the one- and two-dimensional electron gas

International Nuclear Information System (INIS)

Emery, V.J.

1987-01-01

Two topics are discussed: (1) the competition between 2k/sub F/ and 4k/sub F/ charge state waves in a one-dimensional electron gas and (2) a two-dimensional model of high T/sub c/ superconductivity in the oxides

Present status of intermediate band solar cell research

International Nuclear Information System (INIS)

Cuadra, L.; Marti, A.; Luque, A.

2004-01-01

The intermediate band solar cell is a theoretical concept with the potential for exceeding the performance of conventional single-gap solar cells. This novel photovoltaic converter bases its superior theoretical efficiency over single-gap solar cells by enhancing its photogenerated current, via the two-step absorption of sub-band gap photons, without reducing its output voltage. This is achieved through a material with an electrically isolated and partially filled intermediate band located within a higher forbidden gap. This material is commonly named intermediate band material. This paper centres on summarising the present status of intermediate band solar cell research. A number of attempts, which aim to implement the intermediate band concept, are being followed: the direct engineering of the intermediate band material, its implementation by means of quantum dots and the highly porous material approach. Among other sub-band gap absorbing proposals, there is a renewed interest on the impurity photovoltaic effect, the quantum well solar cells and the particularly promising proposal for the use of up- and down-converters

Reactive intermediates in the gas phase generation and monitoring

CERN Document Server

Setser, D W

2013-01-01

Reactive Intermediates in the Gas Phase: Generation and Monitoring covers methods for reactive intermediates in the gas phase. The book discusses the generation and measurement of atom and radical concentrations in flow systems; the high temperature flow tubes, generation and measurement of refractory species; and the electronically excited long-lived states of atoms and diatomic molecules in flow systems. The text also describes the production and detection of reactive species with lasers in static systems; the production of small positive ions in a mass spectrometer; and the discharge-excite

Magnetotransport in a quasi-one-dimensional electron system over superfluid helium

International Nuclear Information System (INIS)

Nikolaenko, V.A.; Kovdrya, Yu.Z.; Gladchenko, S.P.

2002-01-01

Magnetotransport in a nondegenerate quasi-one-dimensional electron system (Q1D) over superfluid helium is investigated experimentally. The experiments were carried out at perpendicular magnetic fields, B xx of the conducting channels mainly grows with increasing B for both the electron-gas atom scattering (T > 0.9 K) and the electron-ripplon scattering (T c τ>1(here ω c is the cyclotron frequency and t is the relaxation time of the electron system) agree qualitatively with the self-consistent Born approximation theory for a 2D electron system over helium. It is supposed that the quantitative discrepancies in the experimental and theoretical data are connected with different peculiar features of the investigated and analyzed electron systems. The experimental data on electron mobility at low temperatures and small magnetic fields coincide with the theoretical calculation made for the Q1D system. The negative magnetoresistance of the channels observed both in the electron-gas scattering and electron-ripplon scattering regions is supposed to be due to weak localization of carriers in the investigated electron system

Gravity with Intermediate Goods Trade

Directory of Open Access Journals (Sweden)

Sujin Jang

2017-12-01

Full Text Available This paper derives the gravity equation with intermediate goods trade. We extend a standard monopolistic competition model to incorporate intermediate goods trade, and show that the gravity equation with intermediates trade is identical to the one without it except in that gross output should be used as the output measure instead of value added. We also show that the output elasticity of trade is significantly underestimated when value added is used as the output measure. This implies that with the conventional gravity equation, the contribution of output growth can be substantially underestimated and the role of trade costs reduction can be exaggerated in explaining trade expansion, as we demonstrate for the case of Korea's trade growth between 1995 and 2007.

Improved tribological properties of TiC with porous nanostructured TiO{sub 2} intermediate layer

Energy Technology Data Exchange (ETDEWEB)

Shanaghi, Ali, E-mail: alishanaghi@gmail.com [Surface Engineering Laboratory, Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Ahangarani, Shahrokh, E-mail: sh.ahangarani@gmail.com [Advanced Materials and Renewable Energies Department, Iranian Research Organization for Science and Technology, P.O. Box 15815-3538, Tehran (Iran, Islamic Republic of); Sabour Rouhaghdam, Ali Reza, E-mail: sabour01@modares.ac.ir [Surface Engineering Laboratory, Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2011-12-15

Highlights: Black-Right-Pointing-Pointer The porous TiO{sub 2} nanoparticle coating is deposited as an intermediate layer on steel. Black-Right-Pointing-Pointer A homogenous and low friction TiC nanostructure coating is deposited by plasma CVD. Black-Right-Pointing-Pointer Intermediate layer can be determined the nucleation and growth of the TiC coating. Black-Right-Pointing-Pointer The porous interlayer improves the friction and wear of the TiC nanostructure coating. - Abstract: The mismatch in the thermal expansion coefficients between TiC coatings and steel substrates and residual stress in the TiC degrade the tribological properties. In this work, a porous nanostructured TiO{sub 2} coating is deposited as an intermediate layer on hot-work steel (H{sub 11}) before final deposition of the TiC film. This intermediate layer is expected to reduce the interfacial energy, decreases the thermal mismatch between TiC and steel, and improves the tribological properties. Grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and pin-on-disk are used to study the structure as well as tribological properties such as friction, wear, and hardness. Our results reveal that the porous TiO{sub 2} interlayer improves the friction, wear, hardness, and elastic modulus of the system.

Projecting non-diffracting waves with intermediate-plane holography.

Science.gov (United States)

Mondal, Argha; Yevick, Aaron; Blackburn, Lauren C; Kanellakopoulos, Nikitas; Grier, David G

2018-02-19

We introduce intermediate-plane holography, which substantially improves the ability of holographic trapping systems to project propagation-invariant modes of light using phase-only diffractive optical elements. Translating the mode-forming hologram to an intermediate plane in the optical train can reduce the need to encode amplitude variations in the field, and therefore complements well-established techniques for encoding complex-valued transfer functions into phase-only holograms. Compared to standard holographic trapping implementations, intermediate-plane holograms greatly improve diffraction efficiency and mode purity of propagation-invariant modes, and so increase their useful non-diffracting range. We demonstrate this technique through experimental realizations of accelerating modes and long-range tractor beams.

Intermediate temperature embrittlement of one new Ni-26W-6Cr based superalloy for molten salt reactors

Energy Technology Data Exchange (ETDEWEB)

Jiang, Li [Thorium Molten Salts Reactor Center, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Science, Beijing 100049 (China); Ye, Xiangxi [University of Chinese Academy of Science, Beijing 100049 (China); Cui, Chuanyong [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Huang, Hefei; Leng, Bin [Thorium Molten Salts Reactor Center, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Li, Zhijun, E-mail: lizhijun@sinap.ac.cn [Thorium Molten Salts Reactor Center, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhou, Xingtai [Thorium Molten Salts Reactor Center, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

2016-06-21

Ni-26W-6Cr based superalloy is considered a potential structure material for the molten salt reactors due to its high strength and good compatibility with the fluoride salt. In the present work, the temperature dependence of the tensile behavior of the alloy was studied by tensile tests in the temperature range of 25–850 °C. This alloy exhibited a good ductility at RT and 450 °C, a ductility minimum from 650 to 750 °C and an intermediate ductility at 850 °C. TEM and EBSD characterization was performed on specimens tested at three typical temperature points (RT, 650 °C and 850 °C) to determine the deformation and fracture mechanisms accounting for the intermediate temperature embrittlement. At RT, the grain boundaries can accommodate enough dislocations to provide compatibility of the sliding between adjacent grains, then M{sub 6}C carbides act as crack origins and cause the fracture. In case of 650 °C, the grain boundaries cannot withstand the local stress even if only a small number of dislocation pile-ups exist. The premature cracks at grain boundaries impede the development of plastic deformation from single slips to multiple ones and cause the low ductility. If tested at 850 °C, the fracture process is retarded by the dynamic recovery and local dynamic recrystallization at crack tips.

Parameter-free one-center model potential for an effective one-electron description of molecular hydrogen

DEFF Research Database (Denmark)

Lühr, Armin Christian; Vanne, Yulian; Saenz, Alejandro

2008-01-01

For the description of an H2 molecule, an effective one-electron model potential is proposed which is fully determined by the exact ionization potential of the H2 molecule. In order to test the model potential and examine its properties, it is employed to determine excitation energies, transition...

Detection of an ylide intermediate in the electrochemically-induced Stevens rearrangement of an ammonium salt by in situ UV–vis spectroelectrochemistry

International Nuclear Information System (INIS)

Capobianco, Amedeo; Caruso, Tonino; Palombi, Laura; Peluso, Andrea

2013-01-01

Highlights: ► Mechanistic insights of the electro-induced Stevens rearrangement are provided. ► The reduction of PhCOCH 2 N + (CH 3 ) 2 CH 2 Ph is ascribed to a one-electron transfer process. ► An electrogenerated ammonium ylide has been detected by UV-spectroelectrochemistry. -- Abstract: The electrochemically-induced Stevens rearrangement of 2-(benzyldimethyl)ammonium acetophenone has been investigated by in situ UV–vis spectroelectrochemistry. Voltammetric analysis and absorption spectra recorded during the potentiostatic reduction indicate that the reaction proceeds via a one-electron transfer with a Platinum cathode and generation of an ammonium ylide intermediate

Advanced intermediate temperature sodium-nickel chloride batteries with ultra-high energy density

Science.gov (United States)

Li, Guosheng; Lu, Xiaochuan; Kim, Jin Y.; Meinhardt, Kerry D.; Chang, Hee Jung; Canfield, Nathan L.; Sprenkle, Vincent L.

2016-02-01

Sodium-metal halide batteries have been considered as one of the more attractive technologies for stationary electrical energy storage, however, they are not used for broader applications despite their relatively well-known redox system. One of the roadblocks hindering market penetration is the high-operating temperature. Here we demonstrate that planar sodium-nickel chloride batteries can be operated at an intermediate temperature of 190 °C with ultra-high energy density. A specific energy density of 350 Wh kg-1, higher than that of conventional tubular sodium-nickel chloride batteries (280 °C), is obtained for planar sodium-nickel chloride batteries operated at 190 °C over a long-term cell test (1,000 cycles), and it attributed to the slower particle growth of the cathode materials at the lower operating temperature. Results reported here demonstrate that planar sodium-nickel chloride batteries operated at an intermediate temperature could greatly benefit this traditional energy storage technology by improving battery energy density, cycle life and reducing material costs.

Electron capture in ion-molecule collisions at intermediate energy

International Nuclear Information System (INIS)

Kumura, M.

1986-01-01

Recent progress of theoretical charge transfer study in ion-molecule collisions at the intermediate energy is reviewed. Concept of close and distant collisions obtained from extensive ion-atom collision studies is identified so that it can be utilized to model two distinct collision processes. For a close collision, explicit representation of the whole collision complex is necessary to describe collision dynamics correctly, while a model potential approach for molecule is appropriate for a distant collision. It is shown that these two distinct models are indeed capable of reproducing experimental charge transfer cross sections. Some remarks for further theoretical study of ion-molecule collisions are also given. 21 refs., 8 figs

Formation of intermediate shocks in both two-fluid and hybrid models

International Nuclear Information System (INIS)

Wu, C.C.; Hada, T.

1991-01-01

Intermediate shocks are shocks with shock frame fluid velocities greater than the Alfven speed ahead and less than the Alfven speed behind, or equivalently, across intermediate shocks the sign of the transverse component of the magnetic field changes. These shocks had been considered extraneous, or nonevolutionary, or unstable, and they had been thought not to correspond to physical reality [Germain, 1960; Jeffrey and Taniuti, 1964; Kantrowitz and Petschek, 1966]. However, it has been shown that intermediate shocks can be formed from continuous waves according to dissipative magnetohydrodynamics (MHD) [Wu, 1987, 1988a, b, 1990]. Thus according to the formation argument which requires that physical shocks be formed by the wave steepening process, the intermediate shocks should be considered physical. Here, intermediate shocks are studied in a two-fluid model that includes finite ion inertia dispersion and in a hybrid model in which the full ion dynamics is retained while the electrons are treated as a massless fluid. The authors show that in both models intermediate shocks can be formed through wave steepening, meaning that they are stable and possess shock structures

One-dimensional versus two-dimensional electronic states in vicinal surfaces

International Nuclear Information System (INIS)

Ortega, J E; Ruiz-Oses, M; Cordon, J; Mugarza, A; Kuntze, J; Schiller, F

2005-01-01

Vicinal surfaces with periodic arrays of steps are among the simplest lateral nanostructures. In particular, noble metal surfaces vicinal to the (1 1 1) plane are excellent test systems to explore the basic electronic properties in one-dimensional superlattices by means of angular photoemission. These surfaces are characterized by strong emissions from free-electron-like surface states that scatter at step edges. Thereby, the two-dimensional surface state displays superlattice band folding and, depending on the step lattice constant d, it splits into one-dimensional quantum well levels. Here we use high-resolution, angle-resolved photoemission to analyse surface states in a variety of samples, in trying to illustrate the changes in surface state bands as a function of d

Electron-positron pair production and bremsstrahlung at intermediate energies in the field of heavy atoms

International Nuclear Information System (INIS)

Lee, R.N.; Milstein, A.I.; Strakhovenko, V.M.; Schwartz, O.Ya.

2006-01-01

The Coulomb corrections (CC) to the processes of bremsstrahlung and pair production are investigated. The next-to-leading term in the high-energy asymptotics is found. This term becomes very essential in the region of intermediate energies. The influence of screening for CC is small for differential cross section, spectrum, and the total cross section of pair production. The same is true for the spectrum of bremsstrahlung, but not for the differential cross section, where the influence of screening can be very large. The corresponding screening corrections as well as the modification of the differential cross section of bremsstrahlung are found. A comparison of our results for the total cross section of pair production with the experimental data available is performed. This comparison has justified our analytical results and allowed to elaborate a simple ansatz for the next-to-leading correction. The influence of the electron beam shape on CC for bremsstrahlung is investigated. It turns out that the differential cross section is very sensitive to this shape

Kinetic advantage of controlled intermediate nuclear fusion

International Nuclear Information System (INIS)

Guo Xiaoming

2012-01-01

The dominated process of controlled fusion is to let nuclei gain enough kinetic energy to overcome Coulomb barrier. As a result, a fusion scheme can consider two factors in its design: to increase kinetic energy of nuclei and to alter the Coulomb barrier. Cold Fusion and Hot fusion are all one-factor schemes while Intermediate Fusion is a twofactors scheme. This made CINF kinetically superior. Cold Fusion reduces deuteron-deuteron distance, addressing Coulomb barrier, and Hot Fusion heat up plasma into extreme high temperature, addressing kinetic energy. Without enough kinetic energy made Cold Fusion skeptical. Extreme high temperature made Hot Fusion very difficult to engineer. Because CIFN addresses both factors, CIFN is a more promising technique to be industrialized.

Oxidative demethylation of lanosterol in cholesterol biosynthesis: accumulation of sterol intermediates

International Nuclear Information System (INIS)

Shafiee, A.; Trzaskos, J.M.; Paik, Y.K.; Gaylor, J.L.

1986-01-01

With [ 3 H-24,25]-dihydrolanosterol as substrate, large-scale metabolic formation of intermediates of lanosterol demethylation was carried out to identify all compounds in the metabolic process. Utilizing knowledge of electron transport of lanosterol demethylation, we interrupted the demethylation reaction allowing accumulation and confirmation of the structure of the oxygenated intermediates lanost-8-en-3 beta,32-diol and 3 beta-hydroxylanost-8-en-32-al, as well as the demethylation product 4,4-dimethyl-cholesta-8,14-dien-3 beta-ol. Further metabolism of the delta 8.14-diene intermediate to a single product 4,4-dimethyl-cholest-8-en-3 beta-ol occurs under interruption conditions in the presence of 0.5 mM CN-1. With authentic compounds, each intermediate has been rigorously characterized by high performance liquid chromatography and gas-liquid chromatography plus mass spectral analysis of isolated and derivatized sterols. Intermediates that accumulated in greater abundance were further characterized by ultraviolet, 1 H-NMR, and infrared spectroscopy of the isolated sterols

Multiplet effects in the electronic structure of intermediate-valence compounds

DEFF Research Database (Denmark)

Thunström, P.; Di Marco, I.; Grechnev, A.

2009-01-01

We present an implementation of the Hubbard-I approximation based on the exact solution of the atomic many-body problem incorporated in a full-potential linear muffin-tin orbital method of density-functional theory. Comparison between calculated and measured x-ray photoemission spectra reveal a g...... a good agreement for intermediate valence systems in open crystal structures such as YbInCu4, SmB6, and YbB12. Spectral features of the unoccupied states of SmB6 are predicted....

Continuous registration of optical absorption spectra of periodically produced solvated electrons

International Nuclear Information System (INIS)

Krebs, P.

1975-01-01

Absorption spectra of unstable intermediates, such as solvated electrons, were usually taken point by point, recording the time-dependent light absorption after their production by a flash. The experimental arrangement for continuous recording of the spectra consists of a conventional one beam spectral photometer with a stabilized white light source, a monochromator, and a light detector. By periodic production of light absorbing intermediates such as solvated electrons, e.g., by ac uv light, a small ac signal is modulated on the light detector output which after amplification can be continuously recorded as a function of wavelength. This method allows the detection of absorption spectra when disturbances from the outside provide a signal-to-noise ratio smaller than 1

Far from the intermediate nuclear field

International Nuclear Information System (INIS)

Dietrich, K.; Wagner, G.J.; Gregoire, C.; Campi, X.; Silvestre-Brac, B.; Platchkov, S.; Mayer, B.; Abgrall, Y.; Bohigas, O.; Grange, P.; Signarbieux, C.

1988-01-01

Pairing correlations in nuclear physics; the BCS state and quasi-particles; the layer model; collision effects on nuclear dynamics; the theory of cluster formation (application to nucleus fragmentation); short range correlations (few-particle systems); deuterium electron scattering; dibaryonic resonances; traditional and exotic hadron probes of nuclear structure; spectral fluctuations and chaotic motion; corrections to the intermediate nuclear field (nonrelativistic and other effects); and heavy nuclei splitting and nuclear superfluidity are introduced [fr

A method of producing small grain Ru intermediate layers for perpendicular magnetic media

International Nuclear Information System (INIS)

Yuan Hua; Qin Yueling; Laughlin, David E.

2008-01-01

NiAl + SiO 2 thin films were used as a grain size reducing seedlayer for cobalt alloy granular perpendicular magnetic recording media. The effect of this NiAl + SiO 2 seedlayer on the microstructure and crystalline orientation of Ru intermediate layer has been investigated. By co-sputtering the composite NiAl + SiO 2 seedlayer, the smallest average grain diameter of NiAl was significantly reduced to about 2.5 nm. The grain size of the subsequent Ru intermediate layer was reduced to about 4 nm. X-ray diffraction results indicate an epitaxial orientation relationship of NiAl (110) // Ru (0002) between the two layers. Moreover, significant improvement of this epitaxial relationship was developed, which produced narrow c-axis distribution of the Ru intermediate layer with small grain size. The addition of the NiAl + SiO 2 seedlayer is a very promising approach to reduce the Ru intermediate layer grain size and eventually the magnetic layer grain size for perpendicular magnetic recording media without deterioration of other properties of thin films

One-electron reduction of mitomycin c by rat liver : role of cytochrome P-450 and NADPH-cytochrome P-450 reductase

NARCIS (Netherlands)

Vromans, R M; Van de Straat, R; Groeneveld, M.; Vermeulen, N P

1. The role of cytochrome P-450 in the one-electron reduction of mitomycin c was studied in rat hepatic microsomal systems and in reconstituted systems of purified cytochrome P-450. Formation of H2O2 from redox cycling of the reduced mitomycin c in the presence of O2 and the alkylation of

Intermediate energy electron scattering from sodium and potassium

International Nuclear Information System (INIS)

Buckman, S.J.

1979-06-01

This thesis describes an experimental investigation of the interaction of fast electrons with alkali metal atoms. Several of the theoretical models which have been applied to atomic collision processes including the first Born approximation, the Glauber approximation, the optical model and the distorted wave polarized orbital approximation are discussed. The theory of electron-photon coincidence experiments is outlined and the effects of fine and hyperfine structure on the polarization state of photons emitted from an excited atom are calculated for Sodium. The results of elastic scattering measurements on Sodium and Potassium are presented and used to test several theoretical models in their description of the differential cross section at incident energies between 50 and 200eV. Absolute differential and integrated total cross sections for the Potassium resonance lines and Sodium D-lines are presented. Results of the first electron-polarized photon coincidence experiment on the Sodium D-lines are presented and compared with available theoretical calculations

Understand electronics

CERN Document Server

Bishop, Owen

2013-01-01

Understand Electronics provides a readable introduction to the exciting world of electronics for the student or enthusiast with little previous knowledge. The subject is treated with the minimum of mathematics and the book is extensively illustrated.This is an essential guide for the newcomer to electronics, and replaces the author's best-selling Beginner's Guide to Electronics.The step-by-step approach makes this book ideal for introductory courses such as the Intermediate GNVQ.

Electron scattering from nucleons and deuterons at intermediate energies

International Nuclear Information System (INIS)

Burkert, V.

1985-04-01

Recent results from electron scattering of nucleons and deuterons are discussed. A tentative physics program for ELSA employing the polarized electron beams as well as the polarized nucleon and deuteron target facilities is outlined. (orig.)

Techniques to reduce memory requirements for coupled photon-electron transport

International Nuclear Information System (INIS)

Turcksin, Bruno; Ragusa, Jean; Morel, Jim

2011-01-01

In this work, we present two methods to decrease memory needs while solving the photon- electron transport equation. The coupled transport of electrons and photons is of importance in radiotherapy because it describes the interactions of X-rays with matter. One of the issues of discretized electron transport is that the electron scattering is highly forward peaked. A common approximation is to represent the peak in the scattering cross section by a Dirac distribution. This is convenient, but the integration over all angles of this distribution requires the use of Galerkin quadratures. By construction these quadratures impose that the number of flux moments be equal to the number of directions (number of angular fluxes), which is very demanding in terms of memory. In this study, we show that even if the number of moments is not as large as the number of directions, an accurate solution can be obtained when using Galerkin quadratures. Another method to decrease the memory needs involves choosing an appropriate reordering of the energy groups. We show in this paper that an appropriate alternation of photons/electrons groups allows to rewrite one transport problem of n groups as gcd successive transport problems of n/gcd groups where gcd is the greatest common divisor between the number of photon groups and the number of electron groups. (author)

Electron energy-loss spectroscopy of quasi-one-dimensional cuprates and vanadates

International Nuclear Information System (INIS)

Atzkern, S.

2001-01-01

In a combination of experimental and theoretical methods in this thesis the electronic structures of quasi-one-dimensional cuprates and vanadates were studied. For this the momentum-dependent loss function was measured by means of the electron energy-loss spectroscopy in transmission on monocrystals of Li 2 CuO 2 , CuGeO 3 , V 2 O 5 and α'-NaVO 5 . The comparison of the experimental data with results from band-structure and cluster calculations allowed conclusions on the mobility and correlations of the electrons in these systems

Electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ

DEFF Research Database (Denmark)

Sing, M.; Schwingenschlögl, U.; Claessen, R.

2003-01-01

We study the electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ by means of density-functional band theory, Hubbard model calculations, and angle-resolved photoelectron spectroscopy (ARPES). The experimental spectra reveal significant quantitative and qualitative......-dimensional Hubbard model for the low-energy spectral behavior is attributed to interchain coupling and the additional effect of electron-phonon interaction....

Intermediate energy semileptonic probes of the hadronic neutral current

International Nuclear Information System (INIS)

Musolf, M.J.; Donnelly, T.W.; Dubach, J.; Beise, E.J.; Maryland Univ., College Park, MD

1993-06-01

The present status and future prospects of intermediate-energy semileptonic neutral current studies are reviewed. Possibilities for using parity-violating electron scattering from nucleons and nuclei to study hadron structure and nuclear dynamics are emphasized, with particular attention paid to probes of strangeness content in the nucleon. Connections are drawn between such studies and tests of the electroweak gauge theory using electron or neutrino scattering. Outstanding theoretical issues in the interpretation of semileptonic neutral current measurements are highlighted and the prospects for undertaking parity-violating electron or neutrino scattering experiments in the near future are surveyed

Monte Carlo simulation for ion-molecule collisions at intermediate velocity

International Nuclear Information System (INIS)

Kadhane, U R; Mishra, P M; Rajput, J; Safvan, C P; Vig, S

2015-01-01

Electronic energy loss distribution estimation is done under local density distribution using Monte Carlo simulations. These results are used to compare the experimental results of proton-polycyclic aromatic hydrocarbons (PAHs) and proton-nucleobase interactions at intermediate velocity collisions. (paper)

Intermediate valence spectroscopy

International Nuclear Information System (INIS)

Gunnarsson, O.; Schoenhammer, K.

1987-01-01

Spectroscopic properties of intermediate valence compounds are studied using the Anderson model. Due to the large orbital and spin degeneracy N/sub f/ of the 4f-level, 1/N/sub f/ can be treated as a small parameter. This approach provides exact T = 0 results for the Anderson impurity model in the limit N/sub f/ → ∞, and by adding 1/N/sub f/ corrections some properties can be calculated accurately even for N/sub f/ = 1 or 2. In particular valence photoemission and resonance photoemission spectroscopies are studied. A comparison of theoretical and experimental spectra provides an estimate of the parameters in the model. Core level photoemission spectra provide estimates of the coupling between the f-level and the conduction states and of the f-level occupancy. With these parameters the model gives a fair description of other electron spectroscopies. For typical parameters the model predicts two structures in the f-spectrum, namely one structure at the f-level and one at the Fermi energy. The resonance photoemission calculation gives a photon energy dependence for these two peaks in fair agreement with experiment. The peak at the Fermi energy is partly due to a narrow Kondo resonance, resulting from many-body effects and the presence of a continuous, partly filled conduction band. This resonance is related to a large density of low-lying excitations, which explains the large susceptibility and specific heat observed for these systems at low temperatures. 38 references, 11 figures, 2 tables

Stepwise expansion of the bacteriophage ϕ6 procapsid: possible packaging intermediates.

Science.gov (United States)

Nemecek, Daniel; Cheng, Naiqian; Qiao, Jian; Mindich, Leonard; Steven, Alasdair C; Heymann, J Bernard

2011-11-25

The initial assembly product of bacteriophage ϕ6, the procapsid, undergoes major structural transformation during the sequential packaging of its three segments of single-stranded RNA. The procapsid, a compact icosahedrally symmetric particle with deeply recessed vertices, expands to the spherical mature capsid, increasing the volume available to accommodate the genome by 2.5-fold. It has been proposed that expansion and packaging are linked, with each stage in expansion presenting a binding site for a particular RNA segment. To investigate procapsid transformability, we induced expansion by acidification, heating, and elevated salt concentration. Cryo-electron microscopy reconstructions after all three treatments yielded the same partially expanded particle. Analysis by cryo-electron tomography showed that all vertices of a given capsid were either in a compact or an expanded state, indicating a highly cooperative transition. To benchmark the mature capsid, we analyzed filled (in vivo packaged) capsids. When these particles were induced to release their RNA, they reverted to the same intermediate state as expanded procapsids (intermediate 1) or to a second, further expanded state (intermediate 2). This partial reversibility of expansion suggests that the mature spherical capsid conformation is obtained only when sufficient outward pressure is exerted by packaged RNA. The observation of two intermediates is consistent with the proposed three-step packaging process. The model is further supported by the observation that a mutant capable of packaging the second RNA segment without previously packaging the first segment has enhanced susceptibility for switching spontaneously from the procapsid to the first intermediate state. Published by Elsevier Ltd.

Transport of a nonneutral electron plasma due to electron collisions with neutral atoms

International Nuclear Information System (INIS)

Douglas, M.H.; O'Neil, T.M.

1978-01-01

Transport of a nonneutral electron plasma across a magnetic field is caused by electron scattering from ambient neutral atoms. A theoretical model of such transport is presented, assuming the plasma is quiescent and the scattering is elastic scattering from infinite mass scattering centers of constant momentum transfer cross section. This model is motivated by recent experiments. A reduced transport equation is obtained by expanding the Boltzmann equation for the electron distribution in inverse powers of the magnetic field. The equation together with Poisson's equation for the radial electric field, which must exist in a nonneutral column, determine the evolution of the system. When these two equations are properly scaled, they contain only a single parameter: the ratio of initial Debye length to initial column radius. For cases where this parameter is either large or small, analytical solutions, or at least partial solutions, are obtained. For intermediate values of the parameter, numerical solutions are obtained

Beyond total treatment effects in randomised controlled trials: Baseline measurement of intermediate outcomes needed to reduce confounding in mediation investigations.

Science.gov (United States)

Landau, Sabine; Emsley, Richard; Dunn, Graham

2018-06-01

Random allocation avoids confounding bias when estimating the average treatment effect. For continuous outcomes measured at post-treatment as well as prior to randomisation (baseline), analyses based on (A) post-treatment outcome alone, (B) change scores over the treatment phase or (C) conditioning on baseline values (analysis of covariance) provide unbiased estimators of the average treatment effect. The decision to include baseline values of the clinical outcome in the analysis is based on precision arguments, with analysis of covariance known to be most precise. Investigators increasingly carry out explanatory analyses to decompose total treatment effects into components that are mediated by an intermediate continuous outcome and a non-mediated part. Traditional mediation analysis might be performed based on (A) post-treatment values of the intermediate and clinical outcomes alone, (B) respective change scores or (C) conditioning on baseline measures of both intermediate and clinical outcomes. Using causal diagrams and Monte Carlo simulation, we investigated the performance of the three competing mediation approaches. We considered a data generating model that included three possible confounding processes involving baseline variables: The first two processes modelled baseline measures of the clinical variable or the intermediate variable as common causes of post-treatment measures of these two variables. The third process allowed the two baseline variables themselves to be correlated due to past common causes. We compared the analysis models implied by the competing mediation approaches with this data generating model to hypothesise likely biases in estimators, and tested these in a simulation study. We applied the methods to a randomised trial of pragmatic rehabilitation in patients with chronic fatigue syndrome, which examined the role of limiting activities as a mediator. Estimates of causal mediation effects derived by approach (A) will be biased if one of

Conformational control of cofactors in nature: The effect of methoxy group orientation on the electronic structure of ubisemiquinone

Science.gov (United States)

De Almeida, Wagner B.; O'Malley, Patrick J.

2018-03-01

Ubiquinone is the key electron and proton transfer agent in biology. Its mechanism involves the formation of its intermediate one-electron reduced form, the ubisemiquinone radical. This is formed in a protein-bound form which permits the semiquinone to vary its electronic and redox properties. This can be achieved by hydrogen bonding acceptance by one or both oxygen atoms or as we now propose by restricted orientations for the methoxy groups of the headgroup. We show how the orientation of the two methoxy groups of the quinone headgroup affects the electronic structure of the semiquinone form and demonstrate a large dependence of the ubisemiquinone spin density distribution on the orientation each methoxy group takes with respect to the headgroup ring plane. This is shown to significantly modify associated hyperfine couplings which in turn needs to be accounted for in interpreting experimental values in vivo. The study uncovers the key potential role the methoxy group orientation can play in controlling the electronic structure and spin density of ubisemiquinone and provides an electronic-level insight into the variation in electron affinity and redox potential of ubiquinone as a function of the methoxy orientation. Taken together with the already known influence of cofactor conformation on heme and chlorophyll electronic structure, it reveals a more widespread role for cofactor conformational control of electronic structure and associated electron transfer in biology.

Synthesis, nanostructure and magnetic properties of FeCo-reduced graphene oxide composite films by one-step electrodeposition

International Nuclear Information System (INIS)

Cao, Derang; Li, Hao; Wang, Zhenkun; Wei, Jinwu; Wang, Jianbo; Liu, Qingfang

2015-01-01

FeCo-reduced graphene oxide (FeCo-RGO) composite film was fabricated on indium tin oxide substrate using one-step electrodeposition method. Raman spectroscopy and field emission scanning electron microscope results show that the reduced graphene oxide is coprecipitated with the FeCo film. The energy-dispersive spectrometer results demonstrate that the atomic ratio of Fe/Co in FeCo-RGO composite film is larger than that of the FeCo film under the same fabrication condition. As a result, the FeCo-RGO composite film exhibits good soft magnetic properties and high-frequency properties as well as the FeCo film. The magnetic anisotropy field and saturation magnetization of FeCo-RGO composite film are increased when compared with FeCo film. Furthermore, the ferromagnetic resonance frequency is improved from 2.15 GHz for the FeCo film to 3.9 GHz for the FeCo-RGO composite film. - Highlights: • FeCo-reduced graphene oxide composite film was fabricated on indium tin oxide substrate. • One step electrodeposition method was used. • Good soft magnetic properties were exhibited by the composite films. • Increase of resonance frequency from 2.15 GHz for FeCo film to 3.9 GHz for composite film

Polarization phenomena in electromagnetic interactions at intermediate energies

International Nuclear Information System (INIS)

Burkert, V.

1990-01-01

Recent results of polarization measurements in electromagnetic interactions at intermediate energies are discussed. Prospects of polarization experiments at the new CW electron accelerators, as well as on upgraded older machines are outlined. It is concluded that polarization experiments will play a very important role in the study of the structure of the nucleon and of light nuclei. 72 refs

Low Power LDPC Code Decoder Architecture Based on Intermediate Message Compression Technique

Science.gov (United States)

Shimizu, Kazunori; Togawa, Nozomu; Ikenaga, Takeshi; Goto, Satoshi

Reducing the power dissipation for LDPC code decoder is a major challenging task to apply it to the practical digital communication systems. In this paper, we propose a low power LDPC code decoder architecture based on an intermediate message-compression technique which features as follows: (i) An intermediate message compression technique enables the decoder to reduce the required memory capacity and write power dissipation. (ii) A clock gated shift register based intermediate message memory architecture enables the decoder to decompress the compressed messages in a single clock cycle while reducing the read power dissipation. The combination of the above two techniques enables the decoder to reduce the power dissipation while keeping the decoding throughput. The simulation results show that the proposed architecture improves the power efficiency up to 52% and 18% compared to that of the decoder based on the overlapped schedule and the rapid convergence schedule without the proposed techniques respectively.

Variable mycorrhizal benefits on the reproductive output of Geranium sylvaticum, with special emphasis on the intermediate phenotype.

Science.gov (United States)

Varga, S; Kytöviita, M-M

2014-03-01

In several gynodioecious species, intermediate sex between female and hermaphrodite has been reported, but few studies have investigated fitness parameters of this intermediate phenotype. Here, we examined the interactions between plant sex and arbuscular mycorrhizal (AM) fungal species affecting the reproductive output of Geranium sylvaticum, a sexually polymorphic plant species with frequent intermediate sexes between females and hermaphrodites, using a common garden experiment. Flowering phenology, AM colonisation levels and several plant vegetative and reproductive parameters, including seed and pollen production, were measured. Differences among sexes were detected in flowering, fruit set, pollen production and floral size. The two AM species used in the present work had different effects on plant fitness parameters. One AM species increased female fitness through increasing seed number and seed mass, while the other species reduced seed mass in all sexes investigated. AM fungi did not affect intermediate and hermaphrodite pollen content in anthers. The three sexes in G. sylvaticum did not differ in their reproductive output in terms of total seed production, but hermaphrodites had potentially larger fathering ability than intermediates due to higher anther number. The ultimate female function--seed production--did not differ among the sexes, but one of the AM fungi used potentially decreased host plant fitness. In addition, in the intermediate sex, mycorrhizal symbiosis functioned similarly in females as in hermaphrodites. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

Time-dependent reduced density matrix functional theory applied to laser-driven, correlated two-electron dynamics

Energy Technology Data Exchange (ETDEWEB)

Brics, Martins; Kapoor, Varun; Bauer, Dieter [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany)

2013-07-01

Time-dependent density functional theory (TDDFT) with known and practicable exchange-correlation potentials does not capture highly correlated electron dynamics such as single-photon double ionization, autoionization, or nonsequential ionization. Time-dependent reduced density matrix functional theory (TDRDMFT) may remedy these problems. The key ingredients in TDRDMFT are the natural orbitals (NOs), i.e., the eigenfunctions of the one-body reduced density matrix (1-RDM), and the occupation numbers (OCs), i.e., the respective eigenvalues. The two-body reduced density matrix (2-RDM) is then expanded in NOs, and equations of motion for the NOs can be derived. If the expansion coefficients of the 2-RDM were known exactly, the problem at hand would be solved. In practice, approximations have to be made. We study the prospects of TDRDMFT following a top-down approach. We solve the exact two-electron time-dependent Schroedinger equation for a model Helium atom in intense laser fields in order to study highly correlated phenomena such as the population of autoionizing states or single-photon double ionization. From the exact wave function we calculate the exact NOs, OCs, the exact expansion coefficients of the 2-RDM, and the exact potentials in the equations of motion. In that way we can identify how many NOs and which level of approximations are necessary to capture such phenomena.

Structure of intermediate shocks in collisionless anisotropic Hall-magnetohydrodynamics plasma models

International Nuclear Information System (INIS)

Sánchez-Arriaga, G.

2013-01-01

The existence of discontinuities within the double-adiabatic Hall-magnetohydrodynamics (MHD) model is discussed. These solutions are transitional layers where some of the plasma properties change from one equilibrium state to another. Under the assumption of traveling wave solutions with velocity C and propagation angle θ with respect to the ambient magnetic field, the Hall-MHD model reduces to a dynamical system and the waves are heteroclinic orbits joining two different fixed points. The analysis of the fixed points rules out the existence of rotational discontinuities. Simple considerations about the Hamiltonian nature of the system show that, unlike dissipative models, the intermediate shock waves are organized in branches in parameter space, i.e., they occur if a given relationship between θ and C is satisfied. Electron-polarized (ion-polarized) shock waves exhibit, in addition to a reversal of the magnetic field component tangential to the shock front, a maximum (minimum) of the magnetic field amplitude. The jumps of the magnetic field and the relative specific volume between the downstream and the upstream states as a function of the plasma properties are presented. The organization in parameter space of localized structures including in the model the influence of finite Larmor radius is discussed

COMPUTATIONAL ELECTROCHEMISTRY: AQUEOUS ONE-ELECTRON OXIDATION POTENTIALS FOR SUBSTITUTED ANILINES

Science.gov (United States)

Semiempirical molecular orbital theory and density functional theory are used to compute one-electron oxidation potentials for aniline and a set of 21 mono- and di-substituted anilines in aqueous solution. Linear relationships between theoretical predictions and experiment are co...

Shelf stable intermediate moisture fruit cubes using radiation technology

International Nuclear Information System (INIS)

Mishra, Bibhuti B.; Saxena, Sudhanshu; Gautam, Satyendra; Chander, Ramesh; Sharma, Arun

2009-01-01

A process has been developed to prepare shelf stable ready-to-eat (RTE) intermediate moisture pineapple slices and papaya cubes using radiation technology. The combination of hurdles including osmotic dehydration, blanching, infrared drying, and gamma radiation dose of 1 kGy successfully reduced the microbial load to below detectable limit. The shelf life of the intermediate moisture pineapple slices and papaya cubes was found to be 40 days at ambient temperature (28 ± 2 deg C). The control samples spoiled within 6 days. The RTE intermediate moisture fruit products were found to have good texture, colour and sensory acceptability during this 40 days storage. (author)

Experimental efforts at NIST towards one-electron ions in circular Rydberg states

International Nuclear Information System (INIS)

Tan, Joseph N; Guise, Nicholas D; Brewer, Samuel M

2011-01-01

Experimental effort is underway at NIST to enable tests of theory with one-electron ions synthesized in circular Rydberg states from captured bare nuclei. Problematic effects that limit the accuracy of predicted energy levels for low-lying states are vanishingly small for high-angular-momentum (high-L) states; in particular, the nuclear size correction for high-L states is completely negligible for any foreseeable improvement of measurement precision. As an initial step towards realizing such states, highly charged ions are extracted from the NIST electron beam ion trap (EBIT) and steered through the electrodes of a Penning trap. The goal is to capture bare nuclei in the Penning trap for experiments to make one-electron atoms in circular Rydberg states with dipole (E1) transitions in the optical domain accessible to a frequency comb.

Photon and electron collimator effects on electron output and abutting segments in energy modulated electron therapy

International Nuclear Information System (INIS)

Olofsson, Lennart; Karlsson, Magnus G.; Karlsson, Mikael

2005-01-01

In energy modulated electron therapy a large fraction of the segments will be arranged as abutting segments where inhomogeneities in segment matching regions must be kept as small as possible. Furthermore, the output variation between different segments should be minimized and must in all cases be well predicted. For electron therapy with add-on collimators, both the electron MLC (eMLC) and the photon MLC (xMLC) contribute to these effects when an xMLC tracking technique is utilized to reduce the x-ray induced leakage. Two add-on electron collimator geometries have been analyzed using Monte Carlo simulations: One isocentric eMLC geometry with an isocentric clearance of 35 cm and air or helium in the treatment head, and one conventional proximity geometry with a clearance of 5 cm and air in the treatment head. The electron fluence output for 22.5 MeV electrons is not significantly affected by the xMLC if the shielding margins are larger than 2-3 cm. For small field sizes and 9.6 MeV electrons, the isocentric design with helium in the treatment head or shielding margins larger than 3 cm is needed to avoid a reduced electron output. Dose inhomogeneity in the matching region of electron segments is, in general, small when collimator positions are adjusted to account for divergence in the field. The effect of xMLC tracking on the electron output can be made negligible while still obtaining a substantially reduced x-ray leakage contribution. Collimator scattering effects do not interfere significantly when abutting beam techniques are properly applied

Electron localization in one-dimensional systems

International Nuclear Information System (INIS)

Chao, K.A.

1984-01-01

The pure regional localization and the global localization have been investigated via the inverse participation ratio and te moment analysis. If the envelop function of a localized state is more complicated than the simple exponential function e sup(-r/xi), the inverse participation ratio is inadequate to describe the localization properties of an electron. This is the case discovered recently in a stereo-irregular chain fo atoms including the electron-electron interaction and the structure disorder. The localization properties in this system are analysed in terms of the moments. (Author) [pt

Electronics all-in-one for dummies

CERN Document Server

Lowe, Doug

2011-01-01

Take your electronics skills to the next level! If you're looking for a solitary resource that covers everything you need to know about electronics, then look no further. This friendly-and-straightforward guide introduces the basics of electronics and enhances your learning experience by debunking and explaining concepts such as circuits, analog and digital, schematics, voltage, safety concerns, and more. Packed with nearly 900 pages of detailed information, this book shows you how to develop your own breadboard, design your own circuit, and get savvy with schematics. Cover

Real-space multiple-scattering theory and the electronic structure of systems with full or reduced symmetry

International Nuclear Information System (INIS)

Zhang, X.; Gonis, A.; MacLaren, J.M.

1989-01-01

We present a new real-space multiple-scattering-theory method for the solution of the Schroedinger equation and the calculation of the electronic structure of solid materials with full or reduced symmetry. The method is based on the concept of semi-infinite periodicity (SIP), rather than translational invariance, and on the property of removal invariance of the scattering matrix of systems with SIP. This latter property allows one to replace the usual Brillouin-zone integrals in reciprocal space by a self-consistency equation for the t matrix, which is sufficient for the determination of the Green function and related properties. Because it is developed entirely in direct space, the method provides a unified treatment of the electronic structure of bulk materials, surfaces, interfaces and grain boundaries (coherent or incoherent), impurities of interstitial or substitutional kinds, and can be easily extended to treat concentrated, substitutionally disordered alloys. One of its advantages over methods based on Bloch's theorem and reciprocal space is the great simplicity of setting up and running the associated computer codes even for complex structures, and structures with reduced or no symmetry that lie outside the realm of applicability of conventional methods. We present the results of model calculations for one-dimensional and three-dimensional model systems as well as for three-dimensional realistic materials. Where appropriate, these results are compared with those obtained through conventional techniques, and give an indication of the method's flexibility and reliability. Our applications of this method to this point are discussed, and our plans for future development are presented

Effects of Thermal Resistance on One-Dimensional Thermal Analysis of the Epidermal Flexible Electronic Devices Integrated with Human Skin

Science.gov (United States)

Li, He; Cui, Yun

2017-12-01

Nowadays, flexible electronic devices are increasingly used in direct contact with human skin to monitor the real-time health of human body. Based on the Fourier heat conduction equation and Pennes bio-heat transfer equation, this paper deduces the analytical solutions of one - dimensional heat transfer for flexible electronic devices integrated with human skin under the condition of a constant power. The influence of contact thermal resistance between devices and skin is considered as well. The corresponding finite element model is established to verify the correctness of analytical solutions. The results show that the finite element analysis agrees well with the analytical solution. With bigger thermal resistance, temperature increase of skin surface will decrease. This result can provide guidance for the design of flexible electronic devices to reduce the negative impact that exceeding temperature leave on human skin.

Characterization of intermediate products of solar photocatalytic degradation of ranitidine at pilot-scale.

Science.gov (United States)

Radjenović, Jelena; Sirtori, Carla; Petrović, Mira; Barceló, Damià; Malato, Sixto

2010-04-01

In the present study the mechanisms of solar photodegradation of H(2)-receptor antagonist ranitidine (RNTD) were studied in a well-defined system of a pilot plant scale Compound Parabolic Collector (CPC) reactor. Two types of heterogeneous photocatalytic experiments were performed: catalysed by titanium-dioxide (TiO(2)) semiconductor and by Fenton reagent (Fe(2+)/H(2)O(2)), each one with distilled water and synthetic wastewater effluent matrix. Complete disappearance of the parent compounds and discreet mineralization were attained in all experiments. Furthermore, kinetic parameters, main intermediate products, release of heteroatoms and formation of carboxylic acids are discussed. The main intermediate products of photocatalytic degradation of RNTD have been structurally elucidated by tandem mass spectrometry (MS(2)) experiments performed at quadrupole-time of flight (QqToF) mass analyzer coupled to ultra-performance liquid chromatograph (UPLC). RNTD displayed high reactivity towards OH radicals, although a product of conduction band electrons reduction was also present in the experiment with TiO(2). In the absence of standards, quantification of intermediates was not possible and only qualitative profiles of their evolution could be determined. The proposed TiO(2) and photo-Fenton degradation routes of RNTD are reported for the first time. (c) 2010 Elsevier Ltd. All rights reserved.

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

Theoretical modelling of intermediate band solar cell materials based on metal-doped chalcopyrite compounds

International Nuclear Information System (INIS)

Palacios, P.; Sanchez, K.; Conesa, J.C.; Fernandez, J.J.; Wahnon, P.

2007-01-01

Electronic structure calculations are carried out for CuGaS 2 partially substituted with Ti, V, Cr or Mn to ascertain if some of these systems could provide an intermediate band material able to give a high efficiency photovoltaic cell. Trends in electronic level positions are analyzed and more accurate advanced theory levels (exact exchange or Hubbard-type methods) are used in some cases. The Ti-substituted system seems more likely to yield an intermediate band material with the desired properties, and furthermore seems realizable from the thermodynamic point of view, while those with Cr and Mn might give half-metal structures with applications in spintronics

Theoretical modelling of intermediate band solar cell materials based on metal-doped chalcopyrite compounds

Energy Technology Data Exchange (ETDEWEB)

Palacios, P [Instituto de Energia Solar and Dpt. de Tecnologias Especiales, ETSI de Telecomunicacion, UPM, Ciudad Universitaria s/n, 28040 Madrid (Spain); Sanchez, K [Instituto de Energia Solar and Dpt. de Tecnologias Especiales, ETSI de Telecomunicacion, UPM, Ciudad Universitaria s/n, 28040 Madrid (Spain); Conesa, J C [Instituto de Catalisis y Petroleoquimica, CSIC, Marie Curie 2, Cantoblanco, 28049 Madrid (Spain); Fernandez, J J [Dpt. de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, 28080, Madrid (Spain); Wahnon, P [Instituto de Energia Solar and Dpt. de Tecnologias Especiales, ETSI de Telecomunicacion, UPM, Ciudad Universitaria s/n, 28040 Madrid (Spain)

2007-05-31

Electronic structure calculations are carried out for CuGaS{sub 2} partially substituted with Ti, V, Cr or Mn to ascertain if some of these systems could provide an intermediate band material able to give a high efficiency photovoltaic cell. Trends in electronic level positions are analyzed and more accurate advanced theory levels (exact exchange or Hubbard-type methods) are used in some cases. The Ti-substituted system seems more likely to yield an intermediate band material with the desired properties, and furthermore seems realizable from the thermodynamic point of view, while those with Cr and Mn might give half-metal structures with applications in spintronics.

Three-body forces in nuclear matter from intermediate Δ-states in three-nucleon clusters

International Nuclear Information System (INIS)

Kouki, T.; Smulter, L.E.W.; Green, A.M.

1976-10-01

The three-body force contribution in nuclear matter is treated as a three-nucleon cluster, in which one of the nucleons becomes, in an intermediate state, a Δ(1236). All exchange diagrams are calculated and found to significantly reduce the energy per particle from the direct graph. This is contrary to earlier estimates of the exchanges, using more approximate approaches. The resulting attractive contribution is rather small, -1.1 MeV at ksub(F)=1.4 fm -1 , but the roughly linear density dependence has a crucial effect on the saturation properties. The sensitivity of the results to the correlations used, and to the two-body force spin structure, is displayed. The energy per particle from clusters with three intermediate Δ's is also estimated. (author)

Second derivative Langmuir probe diagnostics of gas discharge plasma at intermediate pressures (review article)

International Nuclear Information System (INIS)

Popov, Tsv K; Dimitrova, M; Dias, F M; Tsaneva, V N; Stelmashenko, N A; Blamire, M G; Barber, Z H

2006-01-01

The second-derivative Langmuir probe method for precise determination of the plasma potential, the electron energy distribution function (respectively the electron temperature,) and the electron density of gas discharge plasma at intermediate pressures (100-1000 Pa) is reviewed. Results of applying the procedure proposed to different kinds of gas discharges are presented. Factors affecting the accuracy of the plasma characteristics evaluated are discussed

Many-electron phenomena in the ionization of ions

International Nuclear Information System (INIS)

Mueller, A.

2004-01-01

Full text: Single and multiple ionization in ion-atom collisions involve a multitude of complex interactions between the electrons and nuclei of projectile and target. Some of the complexity is avoided in studies of fast collisions when the impulse approximation can be applied and the electrons can be described as independent quasi-free particles with a known momentum distribution. For the detailed investigation of ionization mechanisms that can occur in fast ion-atom collisions, it is illuminating to consider collisions of ions (or atoms) and really free electrons with a narrow energy spread. High energy resolution in electron-ion collision studies provides access to individual, possibly even state-selective, reaction pathways. Even in the simple electron-ion collision system (simple compared with the initial ion-atom problem) single and multiple ionization still involve a multitude of complex mechanisms. Besides the direct removal of one or several electrons from the target by electron impact, resonant and non-resonant formation of intermediate multiply excited states which subsequently decay by electron emission is important in single and multiple ionization of ions and atoms. Direct ionization proceeds via one-step or multi-step knock-off mechanisms which can partly be disentangled by studying effects of different projectile species. The role of multiply excited states in the ionization can be experimentally studied in great detail by a further reduction of the initial ion-atom problem. Multiply excited states of atoms and ions can be selectively populated by photon-ion interactions making use of the potential for extreme energy resolution made available at modern synchrotron radiation sources. In the review talk, examples of studies on single and multiple ionization in electron-ion collisions will be discussed in some detail. Electron-ion collision experiments will also be compared with photon-ion interaction studies. Many-electron phenomena have been observed

Properties of the radicals formed by one-electron oxidation of acetaminophen - a pulse radiolysis study

International Nuclear Information System (INIS)

Bisby, R.H.; Tabassum, N.

1988-01-01

The semi-iminoquinone radical of acetaminophen, which has previously been proposed as a possible hepatotoxic intermediate in the cytochrome P-450 catalysed oxidation of acetaminophen, has been generated and studied by pulse radiolysis. In the absence of other reactive solutes, the radical decays rapidly by second order kinetics with a rate constant (2k 2 ) of (2.2 ± 0.4) x 10 9 M -1 sec -1 . In alkaline solutions the radical deprotonates with a pK of 11.1 ± 0.1 to form a radical-anion. The acetaminophen radical-anion reacts with resorcinol at high pH values, leading to the formation of a transient equilibrium from which the one-electron reduction potential of the semi-iminoquinone radical of acetaminophen is estimated to be + 0.707 ± 0.01 V at pH 7. This value predicts that acetaminophen should be oxidised by thiyl radicals. This was confirmed by pulse radiolysis experiments for reaction of the cysteinyl radical, for which rate constants of 7 x 10 6 M -1 sec -1 at pH7 and 2.7 x 10 8 M -1 sec -1 at pH 11.3 were obtained. The reaction of O 2 with the acetaminophen semi-iminoquinone radical could not be detected by pulse radiolysis, and alternative mechanisms for superoxide radical formation are discussed. (author)

Properties of the radicals formed by one-electron oxidation of acetaminophen - a pulse radiolysis study

Energy Technology Data Exchange (ETDEWEB)

Bisby, R H; Tabassum, N

1988-07-15

The semi-iminoquinone radical of acetaminophen, which has previously been proposed as a possible hepatotoxic intermediate in the cytochrome P-450 catalysed oxidation of acetaminophen, has been generated and studied by pulse radiolysis. In the absence of other reactive solutes, the radical decays rapidly by second order kinetics with a rate constant (2k/sub 2/) of (2.2 +- 0.4) x 10/sup 9/ M/sup -1/ sec/sup -1/. In alkaline solutions the radical deprotonates with a pK of 11.1 +- 0.1 to form a radical-anion. The acetaminophen radical-anion reacts with resorcinol at high pH values, leading to the formation of a transient equilibrium from which the one-electron reduction potential of the semi-iminoquinone radical of acetaminophen is estimated to be + 0.707 +- 0.01 V at pH 7. This value predicts that acetaminophen should be oxidised by thiyl radicals. This was confirmed by pulse radiolysis experiments for reaction of the cysteinyl radical, for which rate constants of 7 x 10/sup 6/ M/sup -1/ sec/sup -1/ at pH7 and 2.7 x 10/sup 8/ M/sup -1/ sec/sup -1/ at pH 11.3 were obtained. The reaction of O/sub 2/ with the acetaminophen semi-iminoquinone radical could not be detected by pulse radiolysis, and alternative mechanisms for superoxide radical formation are discussed.

One- and two-electron processes in collisions of heavy ions with H2 and He

International Nuclear Information System (INIS)

Richard, P.; Hall, J.; Shinpaugh, J.L.; Sanders, J.M.; Tipping, T.N.; Zouros, T.J.M.; Lee, D.H.; Schmidt-Boecking, H.

1987-01-01

In this paper we present a description of the apparatus and results for experiments involving one- and two-electron processes in collisions of heavy ions with H 2 and He. The experiments were performed using one-electron and bare projectiles. In the first section we describe the measurement of pure ionization of one-electron projectiles by H 2 targets and compare with previous results for He targets. We also present the results for one-electron capture by the projectile from H 2 targets. The energy dependence of the cross sections is compared to theoretical predictions for atomic and molecular hydrogen targets. Both experiments were performed by measuring only the final charge state of the projectile. In the second section we describe the measurement of partial cross sections for the same collisions by measuring the target recoil charge state in coincidence with the projectile charge state. By this method we can measure pure single- and double-ionization of the target, pure single-electron transfer and transfer ionization, and pure double-electron transfer. This experiment is presently being performed for bare flourine on He; however, absolute cross sections are not available at the time of this conference. (orig.)

One-electron propagation in Fermi, Pasta, Ulam disordered chains with Gaussian acoustic pulse pumping

Science.gov (United States)

Silva, L. D. Da; Dos Santos, J. L. L.; Ranciaro Neto, A.; Sales, M. O.; de Moura, F. A. B. F.

In this work, we consider a one-electron moving on a Fermi, Pasta, Ulam disordered chain under effect of electron-phonon interaction and a Gaussian acoustic pulse pumping. We describe electronic dynamics using quantum mechanics formalism and the nonlinear atomic vibrations using standard classical physics. Solving numerical equations related to coupled quantum/classical behavior of this system, we study electronic propagation properties. Our calculations suggest that the acoustic pumping associated with the electron-lattice interaction promote a sub-diffusive electronic dynamics.

Multi-shell spherical GaAs /AlxGa1-x As quantum dot shells-size distribution as a mechanism to generate intermediate band energy levels

Science.gov (United States)

Rodríguez-Magdaleno, K. A.; Pérez-Álvarez, R.; Martínez-Orozco, J. C.; Pernas-Salomón, R.

2017-04-01

In this work the generation of an intermediate band of energy levels from multi-shell spherical GaAs /AlxGa1-x As quantum dot shells-size distribution is reported. Within the effective mass approximation the electronic structure of a GaAs spherical quantum-dot surrounded by one, two and three shells is studied in detail using a numerically stable transfer matrix method. We found that a shells-size distribution characterized by continuously wider GaAs domains is a suitable mechanism to generate the intermediate band whose width is also dependent on the Aluminium concentration x. Our results suggest that this effective mechanism can be used for the design of wider intermediate band than reported in other quantum systems with possible solar cells enhanced performance.

Intermediate mass distribution of the dual resonance pomeron

International Nuclear Information System (INIS)

Chiu, C.B.; Matsuda, S.

1978-01-01

The intermediate mass distribution of the dual resonance pomeron is determined at the one-loop level and it is shown that the mass distribution obtained is remarkably similar to a suitably defined mass distribution in the dual multiperipheral model. Thus it is suggestive to identify the intermediate states of the dual resonance pomeron with multiperipheral processes. (Auth.)

Hydrogen is a preferred intermediate in the energy-conserving electron transport chain of Methanosarcina barkeri.

Science.gov (United States)

Kulkarni, Gargi; Kridelbaugh, Donna M; Guss, Adam M; Metcalf, William W

2009-09-15

Methanogens use an unusual energy-conserving electron transport chain that involves reduction of a limited number of electron acceptors to methane gas. Previous biochemical studies suggested that the proton-pumping F(420)H(2) dehydrogenase (Fpo) plays a crucial role in this process during growth on methanol. However, Methanosarcina barkeri Delta fpo mutants constructed in this study display no measurable phenotype on this substrate, indicating that Fpo plays a minor role, if any. In contrast, Delta frh mutants lacking the cytoplasmic F(420)-reducing hydrogenase (Frh) are severely affected in their ability to grow and make methane from methanol, and double Delta fpo/Delta frh mutants are completely unable to use this substrate. These data suggest that the preferred electron transport chain involves production of hydrogen gas in the cytoplasm, which then diffuses out of the cell, where it is reoxidized with transfer of electrons into the energy-conserving electron transport chain. This hydrogen-cycling metabolism leads directly to production of a proton motive force that can be used by the cell for ATP synthesis. Nevertheless, M. barkeri does have the flexibility to use the Fpo-dependent electron transport chain when needed, as shown by the poor growth of the Delta frh mutant. Our data suggest that the rapid enzymatic turnover of hydrogenases may allow a competitive advantage via faster growth rates in this freshwater organism. The mutant analysis also confirms the proposed role of Frh in growth on hydrogen/carbon dioxide and suggests that either Frh or Fpo is needed for aceticlastic growth of M. barkeri.

Electron-deuteron deep-inelastic scattering with spectator nucleon tagging and final-state interactions at intermediate x

Science.gov (United States)

Strikman, M.; Weiss, C.

2018-03-01

We consider electron-deuteron deep-inelastic scattering (DIS) with detection of a proton in the nuclear fragmentation region ("spectator tagging") as a method for extracting the free neutron structure functions and studying their nuclear modifications. Such measurements could be performed at a future electron-ion collider (EIC) with suitable forward detectors. The measured proton recoil momentum (≲100 MeV in the deuteron rest frame) specifies the deuteron configuration during the high-energy process and permits a controlled theoretical treatment of nuclear effects. Nuclear and nucleonic structure are separated using methods of light-front quantum mechanics. The impulse approximation to the tagged DIS cross section contains the free neutron pole, which can be reached by on-shell extrapolation in the recoil momentum. Final-state interactions (FSIs) distort the recoil momentum distribution away from the pole. In the intermediate-x region 0.1 rest frame momenta ≲1 GeV , target fragmentation region). We construct a schematic model describing this effect, using final-state hadron distributions measured in nucleon DIS experiments and low-energy hadron scattering amplitudes. We investigate the magnitude of FSIs, their dependence on the recoil momentum (angular dependence, forward/backward regions), their analytic properties, and their effect on the on-shell extrapolation. We comment on the prospects for neutron structure extraction in tagged DIS with an EIC. We discuss possible extensions of the FSI model to other kinematic regions (large/small x ). In tagged DIS at x ≪0.1 FSIs resulting from diffractive scattering on the nucleons become important and require separate treatment.

Electronic structure and transport properties of quasi-one-dimensional carbon nanomaterials

Directory of Open Access Journals (Sweden)

Y. N. Wu

2017-09-01

Full Text Available Based on the density functional theory combined with the nonequilibrium Green’s function, the influence of the wrinkle on the electronic structures and transport properties of quasi-one-dimensional carbon nanomaterials have been investigated, in which the wrinkled armchair graphene nanoribbons (wAGNRs and the composite of AGNRs and single walled carbon nanotubes (SWCNTs were considered with different connection of ripples. The wrinkle adjusts the electronic structures and transport properties of AGNRs. With the change of the strain, the wAGNRs for three width families reveal different electrical behavior. The band gap of AGNR(6 increases in the presence of the wrinkle, which is opposite to that of AGNR(5 and AGNR(7. The transport of AGNRs with the widths 6 or 7 has been modified by the wrinkle, especially by the number of isolated ripples, but it is insensitive to the strain. The nanojunctions constructed by AGNRs and SWCNTs can form the quantum wells, and some specific states are confined in wAGNRs. Although these nanojunctions exhibit the metallic, they have poor conductance due to the wrinkle. The filling of C20 into SWCNT has less influence on the electronic structure and transport of the junctions. The width and connection type of ripples have greatly influenced on the electronic structures and transport properties of quasi-one-dimensional nanomaterials.

Electronic structure and transport properties of quasi-one-dimensional carbon nanomaterials

Science.gov (United States)

Wu, Y. N.; Cheng, P.; Wu, M. J.; Zhu, H.; Xiang, Q.; Ni, J.

2017-09-01

Based on the density functional theory combined with the nonequilibrium Green's function, the influence of the wrinkle on the electronic structures and transport properties of quasi-one-dimensional carbon nanomaterials have been investigated, in which the wrinkled armchair graphene nanoribbons (wAGNRs) and the composite of AGNRs and single walled carbon nanotubes (SWCNTs) were considered with different connection of ripples. The wrinkle adjusts the electronic structures and transport properties of AGNRs. With the change of the strain, the wAGNRs for three width families reveal different electrical behavior. The band gap of AGNR(6) increases in the presence of the wrinkle, which is opposite to that of AGNR(5) and AGNR(7). The transport of AGNRs with the widths 6 or 7 has been modified by the wrinkle, especially by the number of isolated ripples, but it is insensitive to the strain. The nanojunctions constructed by AGNRs and SWCNTs can form the quantum wells, and some specific states are confined in wAGNRs. Although these nanojunctions exhibit the metallic, they have poor conductance due to the wrinkle. The filling of C20 into SWCNT has less influence on the electronic structure and transport of the junctions. The width and connection type of ripples have greatly influenced on the electronic structures and transport properties of quasi-one-dimensional nanomaterials.

Low temperature intermediate band metallic behavior in Ti implanted Si

Energy Technology Data Exchange (ETDEWEB)

Olea, Javier, E-mail: oleaariza@fis.ucm.es; Pastor, David; Garcia-Hemme, Eric; Garcia-Hernansanz, Rodrigo; Prado, Alvaro del; Martil, Ignacio; Gonzalez-Diaz, German

2012-08-31

Si samples implanted with very high Ti doses and subjected to Pulsed-Laser Melting (PLM) have been electrically analyzed in the scope of a two-layer model previously reported based on the Intermediate Band (IB) theory. Conductivity and Hall effect measurements using the van der Pauw technique suggest that the insulator-metal transition takes place for implantation doses in the 10{sup 14}-10{sup 16} cm{sup -2} range. Results of the sample implanted with the 10{sup 16} cm{sup -2} dose show a metallic behavior at low temperature that is explained by the formation of a p-type IB out of the Ti deep levels. This suggests that the IB would be semi-filled, which is essential for IB photovoltaic devices. - Highlights: Black-Right-Pointing-Pointer We fabricated high dose Ti implanted Si samples for intermediate band research. Black-Right-Pointing-Pointer We measured the electronic transport properties in the 7-300 K range. Black-Right-Pointing-Pointer We show an insulator to metallic transition when the intermediate band is formed. Black-Right-Pointing-Pointer The intermediate band is semi-filled and populated by holes. Black-Right-Pointing-Pointer We satisfactorily explain the electrical behavior by an intermediate band model.

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.

Intermediate treatments

Science.gov (United States)

John R. Jones; Wayne D. Shepperd

1985-01-01

Intermediate treatments are those applied after a new stand is successfully established and before the final harvest. These include not only intermediate cuttings - primarily thinning - but also fertilization, irrigation, and protection of the stand from damaging agents.

Intermediate-energy neutron beam for NCT at MURR

International Nuclear Information System (INIS)

Brugger, R.M.; Less, T.J.; Passmore, G.G.

1986-01-01

The University of Missouri Research Reactor (MURR) is one of the high-flux reactors in the USA and it can be used to produce an intense beam of intermediate-energy neutrons for neutron capture therapy. Two methods are being evaluated at MURR to produce such a beam. The first uses a moderator of Al 2 O 3 replacing part of the graphite and water on one side of the core of the reactor to produce a source of predominantly intermediate-energy neutrons. The second method is a filter of 238 U between the core and the patient position to pass only intermediate-energy neutrons. The results of these evaluations are presented in this paper along with an outline of the other resources at the University of Missouri-Columbia that are available to support an NCT program. 4 references, 7 figures, 1 table

Radiolysis studies on reactive intermediates. Final report, February 1, 1970-August 31, 1980

International Nuclear Information System (INIS)

Kevan, L.

1980-08-01

Research highlights are briefly reviewed concerning studies of excess and solvated electrons, development of new electron spin resonance methods for maximizing the geometrical information about the surroundings of paramagnetic species in disordered systems, atom and ion solvation, and studies on other reactive intermediates. Titles of 155 research publications and 182 scientific talks presented on these areas are given

Fate of free radicals generated during one-electron reductions of 4-alkyl-1,4-peroxyquinols by cytochrome P-450

International Nuclear Information System (INIS)

Yumibe, N.P.; Thompson, J.A.

1988-01-01

Free radicals resulting from the one-electron reduction and subsequent homolytic cleavage of oxygen-oxygen bonds by heme proteins are likely to be responsible for some aspects of the toxicity of organic hydroperoxides. In the present work, effects of the 4-alkyl substituent of 2,6-di-tert-butyl-4-alkyl-4-hydroperoxycytohexa-2,5-dienones on radical production were investigated with microsomal cytochrome P-450 from rat liver. Quinoxy radicals from homolysis of the peroxyquinols underwent β-scission to produce a quinone and an alkyl radical, and this process occurred with increasing frequency as the stability of the alkyl radical increased. The fate of benzyl and 2-phenylethyl radicals generated from the appropriately substituted peroxyquinols was investigated also. The former was converted to benzyl alcohol, benzaldehyde, and toluene and the latter to 2-phenylethanol, phenylacetaldehyde, ethylbenzene, styrene, and benzaldehyde. Oxygen-18 labeling studies demonstrate that 80-85% of the benzyl alcohol incorporated oxygen from the hydroperoxide and the balance from molecular oxygen. This indicates that the predominant reaction pathway involved recombination between the benzyl radical and the iron-bound hydroxyl radical of the P-450 intermediate complex. By contrast, about 50% of 2-phenylethanol from the 2-phenylethyl radical incorporated oxygen from water and the balance from O 2 . Two alternative mechanisms are proposed to explain the formation of 2-phenylethanol that contained oxygen from water and the concurrent formation of styrene: (a) oxygen exchange of the P-450 intermediate with water, followed by hydrogen abstraction and radical recombination reactions with the P-450 complex, or (b) oxidation of the radical to the 2-phenylethyl cation followed by proton elimination and hydration

Electron Bifurcation: Thermodynamics and Kinetics of Two-Electron Brokering in Biological Redox Chemistry.

Science.gov (United States)

Zhang, Peng; Yuly, Jonathon L; Lubner, Carolyn E; Mulder, David W; King, Paul W; Peters, John W; Beratan, David N

2017-09-19

How can proteins drive two electrons from a redox active donor onto two acceptors at very different potentials and distances? And how can this transaction be conducted without dissipating very much energy or violating the laws of thermodynamics? Nature appears to have addressed these challenges by coupling thermodynamically uphill and downhill electron transfer reactions, using two-electron donor cofactors that have very different potentials for the removal of the first and second electron. Although electron bifurcation is carried out with near perfection from the standpoint of energy conservation and electron delivery yields, it is a biological energy transduction paradigm that has only come into focus recently. This Account provides an exegesis of the biophysical principles that underpin electron bifurcation. Remarkably, bifurcating electron transfer (ET) proteins typically send one electron uphill and one electron downhill by similar energies, such that the overall reaction is spontaneous, but not profligate. Electron bifurcation in the NADH-dependent reduced ferredoxin: NADP + oxidoreductase I (Nfn) is explored in detail here. Recent experimental progress in understanding the structure and function of Nfn allows us to dissect its workings in the framework of modern ET theory. The first electron that leaves the two-electron donor flavin (L-FAD) executes a positive free energy "uphill" reaction, and the departure of this electron switches on a second thermodynamically spontaneous ET reaction from the flavin along a second pathway that moves electrons in the opposite direction and at a very different potential. The singly reduced ET products formed from the bifurcating flavin are more than two nanometers distant from each other. In Nfn, the second electron to leave the flavin is much more reducing than the first: the potentials are said to be "crossed." The eventually reduced cofactors, NADH and ferredoxin in the case of Nfn, perform crucial downstream redox

One-pot synthesis of reduced graphene oxide supported gold-based nanomaterials as robust nanocatalysts for glucose electrooxidation

International Nuclear Information System (INIS)

Ghosh, Srabanti; Holade, Yaovi; Remita, Hynd; Servat, Karine; Beaunier, Patricia; Hagège, Agnès; Kokoh, K. Boniface

2016-01-01

Highlights: • Fast preparation of graphene nanosheets by one-pot radiolytic reduction of GO. • One-pot synthesis of graphene nanosheets supported Au-Pt-Pd nanoparticles. • Radiolysis enables to engineer highly active Metal/rGO nanocomposites. • Ternary Au_5_0Pt_2_5Pd_2_5/rGO electrocatalyst is 5-fold higher effective than Pt/rGO. • Selective glucose oxidation reaction in a 2-electron process leads to gluconate. - Abstract: We report a novel “one-pot”, convenient and efficient method based on radiolysis to synthesize gold-based nanoparticles finely dispersed on reduced graphene oxide (rGO) nanosheets obtained from reductive transformation of graphene oxide (GO). Extensive characterizations of the metal/rGO nanocomposites were performed and revealed that the optimized bimetallic Au_9_0Pd_1_0 and trimetallic Au_5_0Pd_2_5Pt_2_5 materials were mostly nano-alloyed. Not only the multimetallic catalysts demonstrate high electrocatalytic performances towards glucose in alkaline medium, but they also surpass the majority of the reported noble metals based nanocatalysts. The spectroelectrochemical investigations have highlighted a 2-electron reaction process leading to gluconate, a high added-value chemical used in various industries. Definitely, the strategies developed herein pave new rational pathways for the design of effective anode catalysts for glucose-based electrochemical energy converters and the scalability in the catalyst composition opens up new avenues in the efficient application of graphene-based nanocomposites as promising electrode materials in the electrocatalysis of carbohydrates.

One-carbon metabolism in acetogenic and sulfate-reducing bacteria

NARCIS (Netherlands)

Visser, M.

2015-01-01

ABSTRACT

One-carbon metabolism in acetogenic and sulfate-reducing bacteria

Life on earth is sustained by the constant cycling of six essential elements: oxygen, hydrogen, nitrogen,

Classical model of intermediate statistics

International Nuclear Information System (INIS)

Kaniadakis, G.

1994-01-01

In this work we present a classical kinetic model of intermediate statistics. In the case of Brownian particles we show that the Fermi-Dirac (FD) and Bose-Einstein (BE) distributions can be obtained, just as the Maxwell-Boltzmann (MD) distribution, as steady states of a classical kinetic equation that intrinsically takes into account an exclusion-inclusion principle. In our model the intermediate statistics are obtained as steady states of a system of coupled nonlinear kinetic equations, where the coupling constants are the transmutational potentials η κκ' . We show that, besides the FD-BE intermediate statistics extensively studied from the quantum point of view, we can also study the MB-FD and MB-BE ones. Moreover, our model allows us to treat the three-state mixing FD-MB-BE intermediate statistics. For boson and fermion mixing in a D-dimensional space, we obtain a family of FD-BE intermediate statistics by varying the transmutational potential η BF . This family contains, as a particular case when η BF =0, the quantum statistics recently proposed by L. Wu, Z. Wu, and J. Sun [Phys. Lett. A 170, 280 (1992)]. When we consider the two-dimensional FD-BE statistics, we derive an analytic expression of the fraction of fermions. When the temperature T→∞, the system is composed by an equal number of bosons and fermions, regardless of the value of η BF . On the contrary, when T=0, η BF becomes important and, according to its value, the system can be completely bosonic or fermionic, or composed both by bosons and fermions

Reversal of local spins in transport of electrons through a one-dimensional chain

International Nuclear Information System (INIS)

Hu, D.-S.; Xiong, S.-J.

2003-01-01

We investigate the spin reversal of two coupled magnetic impurities in the transport processes of electrons in a one-dimensional chain. The impurities are side coupled to the chain and the electrons are injected and tunneling through it. The transmission coefficient of electrons and the polarization of impurities are calculated by the use of the equivalent single-particle network method for the correlated system. It is found that both the transmission coefficient and the polarization of impurities depend on the initial state of impurities and the impurity spins can be converted into the direction of electron spin if the injected electrons are polarized and the number of electrons is large enough. The evolution of the spin-reversal processes is studied in details

Photofragment imaging study of the CH2CCH2OH radical intermediate of the OH+allene reaction

International Nuclear Information System (INIS)

Raman, Arjun S.; Justine Bell, M.; Lau, K.-C.; Butler, Laurie J.

2007-01-01

These velocity map imaging experiments characterize the photolytic generation of one of the two radical intermediates formed when OH reacts via an addition mechanism with allene. The CH 2 CCH 2 OH radical intermediate is generated photolytically from the photodissociation of 2-chloro-2-propen-1-ol at 193 nm. Detecting the Cl atoms using [2+1] resonance-enhanced multiphoton ionization evidences an isotropic angular distribution for the Cl+CH 2 CCH 2 OH photofragments, a spin-orbit branching ratio for Cl( 2 P 1/2 ):Cl( 2 P 3/2 ) of 0.28, and a bimodal recoil kinetic energy distribution. Conservation of momentum and energy allows us to determine from this data the internal energy distribution of the nascent CH 2 CCH 2 OH radical cofragment. To assess the possible subsequent decomposition pathways of this highly vibrationally excited radical intermediate, we include electronic structure calculations at the G3//B3LYP level of theory. They predict the isomerization and dissociation transition states en route from the initial CH 2 CCH 2 OH radical intermediate to the three most important product channels for the OH+allene reaction expected from this radical intermediate: formaldehyde+C 2 H 3 , H+acrolein, and ethene+CHO. We also calculate the intermediates and transition states en route from the other radical adduct, formed by addition of the OH to the center carbon of allene, to the ketene+CH 3 product channel. We compare our results to a previous theoretical study of the O+allyl reaction conducted at the CBS-QB3 level of theory, as the two reactions include several common intermediates

Photofragment imaging study of the CH2CCH2OH radical intermediate of the OH +allene reaction

Science.gov (United States)

Raman, Arjun S.; Justine Bell, M.; Lau, Kai-Chung; Butler, Laurie J.

2007-10-01

These velocity map imaging experiments characterize the photolytic generation of one of the two radical intermediates formed when OH reacts via an addition mechanism with allene. The CH2CCH2OH radical intermediate is generated photolytically from the photodissociation of 2-chloro-2-propen-1-ol at 193nm. Detecting the Cl atoms using [2+1] resonance-enhanced multiphoton ionization evidences an isotropic angular distribution for the Cl +CH2CCH2OH photofragments, a spin-orbit branching ratio for Cl(P1/22):Cl(P3/22) of 0.28, and a bimodal recoil kinetic energy distribution. Conservation of momentum and energy allows us to determine from this data the internal energy distribution of the nascent CH2CCH2OH radical cofragment. To assess the possible subsequent decomposition pathways of this highly vibrationally excited radical intermediate, we include electronic structure calculations at the G3//B3LYP level of theory. They predict the isomerization and dissociation transition states en route from the initial CH2CCH2OH radical intermediate to the three most important product channels for the OH +allene reaction expected from this radical intermediate: formaldehyde+C2H3, H +acrolein, and ethene+CHO. We also calculate the intermediates and transition states en route from the other radical adduct, formed by addition of the OH to the center carbon of allene, to the ketene+CH3 product channel. We compare our results to a previous theoretical study of the O +allyl reaction conducted at the CBS-QB3 level of theory, as the two reactions include several common intermediates.

Calculation of two-center one-electron molecular integrals with STOs

International Nuclear Information System (INIS)

Rico, J.F.; Lopez, R.; Paniagua, M.; Ramirez, G.

1991-01-01

A program for the calculation of two-center one-electron integrals (overlap, nuclear attraction and kinetic energy) between real Slater-type orbitals (STOs) is reported. The integrals are obtained by recursion over simple auxiliary matrices, whose elements are calculated in terms of further auxiliary functions evaluated in a quick and accurate way. (orig.)

Dimension-dependent stimulated radiative interaction of a single electron quantum wavepacket

Science.gov (United States)

Gover, Avraham; Pan, Yiming

2018-06-01

In the foundation of quantum mechanics, the spatial dimensions of electron wavepacket are understood only in terms of an expectation value - the probability distribution of the particle location. One can still inquire how the quantum electron wavepacket size affects a physical process. Here we address the fundamental physics problem of particle-wave duality and the measurability of a free electron quantum wavepacket. Our analysis of stimulated radiative interaction of an electron wavepacket, accompanied by numerical computations, reveals two limits. In the quantum regime of long wavepacket size relative to radiation wavelength, one obtains only quantum-recoil multiphoton sidebands in the electron energy spectrum. In the opposite regime, the wavepacket interaction approaches the limit of classical point-particle acceleration. The wavepacket features can be revealed in experiments carried out in the intermediate regime of wavepacket size commensurate with the radiation wavelength.

A CALCULATION OF SEMI-EMPIRICAL ONE-ELECTRON WAVE FUNCTIONS FOR MULTI-ELECTRON ATOMS USED FOR ELEMENTARY PROCESS SIMULATION IN NONLOCAL PLASMA

Directory of Open Access Journals (Sweden)

M. V. Tchernycheva

2017-01-01

Full Text Available Subject of Research. The paper deals with development outcomes for creation method of one-electron wave functions of complex atoms, relatively simple, symmetrical for all atom electrons and free from hard computations. The accuracy and resource intensity of the approach are focused on systematic calculations of cross sections and rate constants of elementary processes of inelastic collisions of atoms or molecules with electrons (ionization, excitation, excitation transfer, and others. Method. The method is based on a set of two iterative processes. At the first iteration step the Schrödinger equation was solved numerically for the radial parts of the electron wave functions in the potential of the atomic core self-consistent field. At the second iteration step the new approximationfor the atomic core field is created that uses found solutions for all one-electron wave functions. The solution optimization for described multiparameter problem is achieved by the use of genetic algorithm. The suitability of the developed method was verified by comparing the calculation results with numerous data on the energies of atoms in the ground and excited states. Main Results. We have created the run-time version of the program for creation of sets of one-electron wave functions and calculation of the cross sections and constants of collisional transition rates in the first Born approximation. The priori available information about binding energies of the electrons for any many-particle system for creation of semi-empirical refined solutions for the one-electron wave functions can be considered at any step of this procedure. Practical Relevance. The proposed solution enables a simple and rapid preparation of input data for the numerical simulation of nonlocal gas discharge plasma. The approach is focused on the calculation of discharges in complex gas mixtures requiring inclusion in the model of a large number of elementary collisional and radiation

Partially folded intermediates during trypsinogen denaturation

Directory of Open Access Journals (Sweden)

Martins N.F.

1999-01-01

Full Text Available The equilibrium unfolding of bovine trypsinogen was studied by circular dichroism, differential spectra and size exclusion HPLC. The change in free energy of denaturation was = 6.99 ± 1.40 kcal/mol for guanidine hydrochloride and = 6.37 ± 0.57 kcal/mol for urea. Satisfactory fits of equilibrium unfolding transitions required a three-state model involving an intermediate in addition to the native and unfolded forms. Size exclusion HPLC allowed the detection of an intermediate population of trypsinogen whose Stokes radii varied from 24.1 ± 0.4 Å to 26.0 ± 0.3 Å for 1.5 M and 2.5 M guanidine hydrochloride, respectively. During urea denaturation, the range of Stokes radii varied from 23.9 ± 0.3 Å to 25.7 ± 0.6 Å for 4.0 M and 6.0 M urea, respectively. Maximal intrinsic fluorescence was observed at about 3.8 M urea with 8-aniline-1-naphthalene sulfonate (ANS binding. These experimental data indicate that the unfolding of bovine trypsinogen is not a simple transition and suggest that the equilibrium intermediate population comprises one intermediate that may be characterized as a molten globule. To obtain further insight by studying intermediates representing different stages of unfolding, we hope to gain a better understanding of the complex interrelations between protein conformation and energetics.

Effect of Intermediate Annealing on Microstructure and Property of 5182 Aluminum Alloy Sheet for Automobile

Directory of Open Access Journals (Sweden)

WANG Yu

2016-09-01

Full Text Available Effect of intermediate annealing on the microstructure and properties of 5182 aluminum alloy sheet with full annealed state (5182-O was investigated by means of optical microscope, scanning electron microscope and universal testing machine. The results indicate that compared with 5182-O sheet without intermediate annealing, 5182-O sheet with intermediate annealing possesses too fine grain size, intermetallic compounds not broken enough, larger size intermetallic particles, less dispersed phase. Yield strength and ultimate tensile strength, work hardening exponent and normal anisotropy of plastic strain ratio decrease but planner anisotropy of plastic strain ratio increases. The mechanical properties and forming ability of 5182-O aluminum alloy sheet and its microstructure are not improved significantly after intermediate annealing.

Evidence of oxygen vacancy and possible intermediate gap state in layered α-MoO{sub 3} single-crystal nanobelts

Energy Technology Data Exchange (ETDEWEB)

Chen, C.Z., E-mail: tcccz@shu.edu.cn; Li, Y.; Tang, X.D.

2016-01-15

Multilayered meso-structured MoO{sub 3} nanobelts have been synthesized by thermally oxidizing a molybdenum chip in a reduced oxygen atmosphere, with a view to disclosing the existence of oxygen vacancy and understanding the mechanism behind the influence of oxygen vacancy on the electronic structure of molybdenum oxides. Based on the measurements from X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM), it is found that the as-grown sample is single-crystal α-MoO{sub 3} with a (001) preferred orientation, which shows an irregular belt-like morphology being composed of some ~20 nm single-crystal thin layers. The present sample includes a lot of oxygen vacancies in the lattice, as evidenced by the considerably reduced coordination number of the central Mo atoms from X-ray absorption spectra (XAS) as well as the red shift of the main Raman peaks. The existence of the oxygen vacancies are further tested by the photoluminescence (PL) results as the main emission peak shows an obvious red shift with the corresponding optical band gap reduced to 2.3 eV. Very importantly, an extra emission positioned at 738 nm (1.68 eV) is believed to originate from the recombination of the electrons from the intermediate band (IB) to the valence band (VB), and the formation of the IB in the gap is also caused by oxygen-ion vacancies.

Intermediate-band photosensitive device with quantum dots embedded in energy fence barrier

Science.gov (United States)

Forrest, Stephen R.; Wei, Guodan

2010-07-06

A plurality of layers of a first semiconductor material and a plurality of dots-in-a-fence barriers disposed in a stack between a first electrode and a second electrode. Each dots-in-a-fence barrier consists essentially of a plurality of quantum dots of a second semiconductor material embedded between and in direct contact with two layers of a third semiconductor material. Wave functions of the quantum dots overlap as at least one intermediate band. The layers of the third semiconductor material are arranged as tunneling barriers to require a first electron and/or a first hole in a layer of the first material to perform quantum mechanical tunneling to reach the second material within a respective quantum dot, and to require a second electron and/or a second hole in a layer of the first semiconductor material to perform quantum mechanical tunneling to reach another layer of the first semiconductor material.

Electric dipole, polarizability and structure of cesium chloride clusters with one-excess electron

International Nuclear Information System (INIS)

Jraij, A.; Allouche, A.R.; Rabilloud, F.; Korek, M.; Aubert-Frecon, M.; Rayane, D.; Compagnon, I.; Antoine, R.; Broyer, M.; Dugourd, Ph.

2006-01-01

The measurement of the electric dipole of gas phase one-excess electron Cs n Cl n-1 clusters is reported together with a theoretical ab initio prediction of stable structures, dipole moments and electronic polarizabilities for these species in their ground state. Results are in agreement with NaCl cubic structures

Oxidase catalysis via aerobically generated hypervalent iodine intermediates

Science.gov (United States)

Maity, Asim; Hyun, Sung-Min; Powers, David C.

2018-02-01

The development of sustainable oxidation chemistry demands strategies to harness O2 as a terminal oxidant. Oxidase catalysis, in which O2 serves as a chemical oxidant without necessitating incorporation of oxygen into reaction products, would allow diverse substrate functionalization chemistry to be coupled to O2 reduction. Direct O2 utilization suffers from intrinsic challenges imposed by the triplet ground state of O2 and the disparate electron inventories of four-electron O2 reduction and two-electron substrate oxidation. Here, we generate hypervalent iodine reagents—a broadly useful class of selective two-electron oxidants—from O2. This is achieved by intercepting reactive intermediates of aldehyde autoxidation to aerobically generate hypervalent iodine reagents for a broad array of substrate oxidation reactions. The use of aryl iodides as mediators of aerobic oxidation underpins an oxidase catalysis platform that couples substrate oxidation directly to O2 reduction. We anticipate that aerobically generated hypervalent iodine reagents will expand the scope of aerobic oxidation chemistry in chemical synthesis.

A Prototypical First-Generation Electronic Cigarette Does Not Reduce Reports of Tobacco Urges or Withdrawal Symptoms among Cigarette Smokers

Directory of Open Access Journals (Sweden)

Arit M. Harvanko

2017-01-01

Full Text Available It is unknown whether first-generation electronic cigarettes reduce smoking urges and withdrawal symptoms following a 24 h deprivation period. This study tested whether a first-generation electronic cigarette reduces smoking urges and withdrawal symptoms in cigarette smokers. Following 24 h of tobacco deprivation, using a within-subjects design, eight nontreatment seeking tobacco cigarette smokers (3 females administered 10 puffs from a conventional cigarette or a first-generation electronic cigarette containing liquid with 0, 8 or 16 mg/ml nicotine. Conventional cigarettes ameliorated smoking urges and electronic cigarettes did not, regardless of nicotine concentration. First-generation electronic cigarettes may not effectively substitute for conventional cigarettes in reducing smoking urges, regardless of nicotine concentration.

Proton and Electron Additions to Iron (II) Dinitrogen Complexes Containing Pendant Amines

Energy Technology Data Exchange (ETDEWEB)

Heiden, Zachariah M.; Chen, Shentan; Labios, Liezel AN; Bullock, R. Morris; Walter, Eric D.; Tyson, Elizabeth L.; Mock, Michael T.

2014-03-10

We describe a single site cis-(H)FeII-N2 complex, generated by the protonation of an iron-carbon bond of a "reduced" iron complex, that models key aspects of proposed protonated intermediates of the E4 state of nitrogenase. The influence on N2 binding from the addition of protons to the pendant amine sites in the second coordination sphere is described. Furthermore, the addition of electrons to the protonated complexes results in H2 loss. The mechanism of H2 loss is explored to draw a parallel to the origin of H2 loss (homolytic or heterolytic) and the nature of N2 coordination in intermediates of the E4 state of nitrogenase.

Plasmonic photocatalytic reactions enhanced by hot electrons in a one-dimensional quantum well

Directory of Open Access Journals (Sweden)

H. J. Huang

2015-11-01

Full Text Available The plasmonic endothermic oxidation of ammonium ions in a spinning disk reactor resulted in light energy transformation through quantum hot charge carriers (QHC, or quantum hot electrons, during a chemical reaction. It is demonstrated with a simple model that light of various intensities enhance the chemical oxidization of ammonium ions in water. It was further observed that light illumination, which induces the formation of plasmons on a platinum (Pt thin film, provided higher processing efficiency compared with the reaction on a bare glass disk. These induced plasmons generate quantum hot electrons with increasing momentum and energy in the one-dimensional quantum well of a Pt thin film. The energy carried by the quantum hot electrons provided the energy needed to catalyze the chemical reaction. The results indicate that one-dimensional confinement in spherical coordinates (i.e., nanoparticles is not necessary to provide an extra excited state for QHC generation; an 8 nm Pt thin film for one-dimensional confinement in Cartesian coordinates can also provide the extra excited state for the generation of QHC.

Intermediate organizations in the innovation process in Mexico

Directory of Open Access Journals (Sweden)

Maria del Pilar Monserrat Pérez Hernández

2016-07-01

Full Text Available The innovation activity depends strongly on the interaction between generating actors and end-users of new knowledge and technologies. There are several intermediate organizations (IO that facilitate translating the needs of the users with the new technologies that are beingdeveloped, in order to satisfy more effectively their demands. This paper analyzes the mediation process involved in the IO in innovative activity in Mexico, to identify structural holes in the innovation process. The relevant results in the Mexican intermediation process points that threeimportant structural holes of the process are missing: one between the negotiation process and sponsorship, the second in marketing and commercial profit of the obtained results and the last one in the regulation and referring activities. It is very important that the detected missinglinks in the intermediation process are filled, because they can hinder considerably the overall profit and benefits that society could obtained of the innovation process.

Imaging and Quantitation of a Succession of Transient Intermediates Reveal the Reversible Self-Assembly Pathway of a Simple Icosahedral Virus Capsid.

Science.gov (United States)

Medrano, María; Fuertes, Miguel Ángel; Valbuena, Alejandro; Carrillo, Pablo J P; Rodríguez-Huete, Alicia; Mateu, Mauricio G

2016-11-30

Understanding the fundamental principles underlying supramolecular self-assembly may facilitate many developments, from novel antivirals to self-organized nanodevices. Icosahedral virus particles constitute paradigms to study self-assembly using a combination of theory and experiment. Unfortunately, assembly pathways of the structurally simplest virus capsids, those more accessible to detailed theoretical studies, have been difficult to study experimentally. We have enabled the in vitro self-assembly under close to physiological conditions of one of the simplest virus particles known, the minute virus of mice (MVM) capsid, and experimentally analyzed its pathways of assembly and disassembly. A combination of electron microscopy and high-resolution atomic force microscopy was used to structurally characterize and quantify a succession of transient assembly and disassembly intermediates. The results provided an experiment-based model for the reversible self-assembly pathway of a most simple (T = 1) icosahedral protein shell. During assembly, trimeric capsid building blocks are sequentially added to the growing capsid, with pentamers of building blocks and incomplete capsids missing one building block as conspicuous intermediates. This study provided experimental verification of many features of self-assembly of a simple T = 1 capsid predicted by molecular dynamics simulations. It also demonstrated atomic force microscopy imaging and automated analysis, in combination with electron microscopy, as a powerful single-particle approach to characterize at high resolution and quantify transient intermediates during supramolecular self-assembly/disassembly reactions. Finally, the efficient in vitro self-assembly achieved for the oncotropic, cell nucleus-targeted MVM capsid may facilitate its development as a drug-encapsidating nanoparticle for anticancer targeted drug delivery.

Estimation of intermediate grade uranium resources. Final report

International Nuclear Information System (INIS)

Lambie, F.W.; Kendall, G.R.; Klahn, L.J.; Davis, J.C.; Harbaugh, J.W.

1980-12-01

The purpose of this project is to analyze the technique currently used by DOE to estimate intermediate grade uranium (0.01 to 0.05% U 3 O 8 ) and, if possible, suggest alternatives to improve the accuracy and precision of the estimate. There are three principal conclusions resulting from this study. They relate to the quantity, distribution and sampling of intermediate grade uranium. While the results of this study must be validated further, they indicate that DOE may be underestimating intermediate level reserves by 20 to 30%. Plots of grade of U 3 O 8 versus tonnage of ore and tonnage U 3 O 8 indicate grade-tonnage relationships that are essentially log-linear, at least down to 0.01% U 3 O 8 . Though this is not an unexpected finding, it may provide a technique for reducing the uncertainty of intermediate grade endowment. The results of this study indicate that a much lower drill hole density is necessary for DOE to estimate uranium resources than for a mining company to calculate ore resources. Though errors in local estimates will occur, they will tend to cancel over the entire deposit

Triggering of 178Hfm2 by photoinduced electron transition

Directory of Open Access Journals (Sweden)

A. Ya. Dzyublik

2013-03-01

Full Text Available We considered the NEET (nuclear excitation by electron transition as a possible triggering mechanism of the isomer 178Hfm2 during ionization of the L3 atomic shell by x-rays. This isomer is assumed to be excited into an intermediate state by E1 electronic transition between M5 and L3 shells. Simple nonrelativistic formulas are derived for the NEET probability. The estimations show the probability to be less than the experimental data of [1] by one order of magnitude. The intermediate level is found to decay bypassing the isomeric level 16+, if the nucleus attributes a triaxial shape in the state and, besides, there exists a level 13- shifted with respect to 15- by 400 keV. We have shown also that the NEET cross section as a function of the energy of x-ray photons , has to accept constant value above the L photoionization threshold in contrast to narrow peak observed by [1].

Measuring frequency of one-dimensional vibration with video camera using electronic rolling shutter

Science.gov (United States)

Zhao, Yipeng; Liu, Jinyue; Guo, Shijie; Li, Tiejun

2018-04-01

Cameras offer a unique capability of collecting high density spatial data from a distant scene of interest. They can be employed as remote monitoring or inspection sensors to measure vibrating objects because of their commonplace availability, simplicity, and potentially low cost. A defect of vibrating measurement with the camera is to process the massive data generated by camera. In order to reduce the data collected from the camera, the camera using electronic rolling shutter (ERS) is applied to measure the frequency of one-dimensional vibration, whose frequency is much higher than the speed of the camera. Every row in the image captured by the ERS camera records the vibrating displacement at different times. Those displacements that form the vibration could be extracted by local analysis with sliding windows. This methodology is demonstrated on vibrating structures, a cantilever beam, and an air compressor to identify the validity of the proposed algorithm. Suggestions for applications of this methodology and challenges in real-world implementation are given at last.

Intermediate care: for better or worse? Process evaluation of an intermediate care model between a university hospital and a residential home

NARCIS (Netherlands)

Plochg, Thomas; Delnoij, Diana M. J.; van der Kruk, Tineke F.; Janmaat, Tonnie A. C. M.; Klazinga, Niek S.

2005-01-01

Background: Intermediate care was developed in order to bridge acute, primary and social care, primarily for elderly persons with complex care needs. Such bridging initiatives are intended to reduce hospital stays and improve continuity of care. Although many models assume positive effects, it is

Transition Metal Donor-Peptide-Acceptor Complexes: From Intramolecular Electron Transfer Reactions to the Study of Reactive Intermediates

Energy Technology Data Exchange (ETDEWEB)

Isied, Stephan S.

2003-03-11

The trans-polyproline (PII) oligomers (Figure 1) are unusually rigid peptide structures which have been extensively studied by our group for peptide mediated intramolecular electron transfer (ET) at long distances. We have previously studied ET across a series of metal ion donor (D) acceptor (A) oligoproline peptides with different distances, driving forces and reorganizational energies. The majority of these experiments involve generating the ET intermediate using pulse radiolysis methods, although more recently photochemical methods are also used. Results of these studies showed that ET across peptides can vary by more than twelve orders of magnitude. Using ruthenium bipyridine donors, ET reaction rate constants across several proline residues (n = 4 - 9) occurred in the millisecond (ms) to {micro}s timescale, thus limiting the proline peptide conformational motions to only minor changes (far smaller than the large changes that occur on the ms to sec timescale, such as trans to cis proline isomerization). The present report describes our large data base of experimental results for D-peptide-A complexes in terms of a model where the involvement of both superexchange and hopping (hole and electron) mechanisms account for the long range ET rate constants observed. Our data shows that the change from superexchange to hopping mechanisms occurs at different distances depending on the type of D and A and their interactions with the peptides. Our model is also consistent with generalized models for superexchange and hopping which have been put forward by a number of theoretical groups to account for long range ET phenomena.

Photo double ionization of He: C3-like wave function for the two electron continuum

Energy Technology Data Exchange (ETDEWEB)

Otranto, S.; Garibotti, C.R. [Conicet and Centro Atomico Bariloche (Argentina); Otranto, S. [Universidad Nacional del Sur, Dept. de Fisica, Bahia Blanca (Argentina)

2002-12-01

We evaluate the triply differential cross-section (TDCS) for photo double ionization (PDI) of helium. A first approximation to the final state can be obtained by neglecting the e-e interaction and the non-orthogonal kinetic energy. This leads to the C2 model which proposes as solution a product of 2 independent Coulomb wave plane waves. A better approximation is the C3 model where the C3 wave describes the e-e motion as independent of the presence of the nucleus and represents it by a Coulomb continuum wave. The C3 wave function mainly consists in the product of 3 Coulomb waves, each one representing the interaction between a pair of particles. We use a C3 final continuum wave function with an inter-electronic effective coordinate to express the nuclear screening. Comparison with the standard C3 model shows that the TDCS is enhanced in the threshold region by effect of the reduced inter-electronic repulsion introduced by the present model. A more accurate description of the intermediate energy region is also obtained. Comparison with recent experimental data shows a good overall agreement of the angular distributions. The theoretical PDI total cross-section shows a relevant improvement in the intermediate energy region relative to the C3 model, which converges to data for photon energies larger than 1 keV.

Photo double ionization of He: C3-like wave function for the two electron continuum

International Nuclear Information System (INIS)

Otranto, S.; Garibotti, C.R.; Otranto, S.

2002-01-01

We evaluate the triply differential cross-section (TDCS) for photo double ionization (PDI) of helium. A first approximation to the final state can be obtained by neglecting the e-e interaction and the non-orthogonal kinetic energy. This leads to the C2 model which proposes as solution a product of 2 independent Coulomb wave plane waves. A better approximation is the C3 model where the C3 wave describes the e-e motion as independent of the presence of the nucleus and represents it by a Coulomb continuum wave. The C3 wave function mainly consists in the product of 3 Coulomb waves, each one representing the interaction between a pair of particles. We use a C3 final continuum wave function with an inter-electronic effective coordinate to express the nuclear screening. Comparison with the standard C3 model shows that the TDCS is enhanced in the threshold region by effect of the reduced inter-electronic repulsion introduced by the present model. A more accurate description of the intermediate energy region is also obtained. Comparison with recent experimental data shows a good overall agreement of the angular distributions. The theoretical PDI total cross-section shows a relevant improvement in the intermediate energy region relative to the C3 model, which converges to data for photon energies larger than 1 keV

Intermediate tree cover can maximize groundwater recharge in the seasonally dry tropics

Science.gov (United States)

Ilstedt, U.; Bargués Tobella, A.; Bazié, H. R.; Bayala, J.; Verbeeten, E.; Nyberg, G.; Sanou, J.; Benegas, L.; Murdiyarso, D.; Laudon, H.; Sheil, D.; Malmer, A.

2016-01-01

Water scarcity contributes to the poverty of around one-third of the world’s people. Despite many benefits, tree planting in dry regions is often discouraged by concerns that trees reduce water availability. Yet relevant studies from the tropics are scarce, and the impacts of intermediate tree cover remain unexplored. We developed and tested an optimum tree cover theory in which groundwater recharge is maximized at an intermediate tree density. Below this optimal tree density the benefits from any additional trees on water percolation exceed their extra water use, leading to increased groundwater recharge, while above the optimum the opposite occurs. Our results, based on groundwater budgets calibrated with measurements of drainage and transpiration in a cultivated woodland in West Africa, demonstrate that groundwater recharge was maximised at intermediate tree densities. In contrast to the prevailing view, we therefore find that moderate tree cover can increase groundwater recharge, and that tree planting and various tree management options can improve groundwater resources. We evaluate the necessary conditions for these results to hold and suggest that they are likely to be common in the seasonally dry tropics, offering potential for widespread tree establishment and increased benefits for hundreds of millions of people. PMID:26908158

Nitric oxide is an obligate bacterial nitrification intermediate produced by hydroxylamine oxidoreductase.

Science.gov (United States)

Caranto, Jonathan D; Lancaster, Kyle M

2017-08-01

Ammonia (NH 3 )-oxidizing bacteria (AOB) emit substantial amounts of nitric oxide (NO) and nitrous oxide (N 2 O), both of which contribute to the harmful environmental side effects of large-scale agriculture. The currently accepted model for AOB metabolism involves NH 3 oxidation to nitrite (NO 2 - ) via a single obligate intermediate, hydroxylamine (NH 2 OH). Within this model, the multiheme enzyme hydroxylamine oxidoreductase (HAO) catalyzes the four-electron oxidation of NH 2 OH to NO 2 - We provide evidence that HAO oxidizes NH 2 OH by only three electrons to NO under both anaerobic and aerobic conditions. NO 2 - observed in HAO activity assays is a nonenzymatic product resulting from the oxidation of NO by O 2 under aerobic conditions. Our present study implies that aerobic NH 3 oxidation by AOB occurs via two obligate intermediates, NH 2 OH and NO, necessitating a mediator of the third enzymatic step.

Statistical analysis of P-wave neutron reduced widths

International Nuclear Information System (INIS)

Joshi, G.C.; Agrawal, H.M.

2000-01-01

The fluctuations of the p-wave neutron reduced widths for fifty one nuclei have been analyzed with emphasis on recent measurements by a statistical procedure which is based on the method of maximum likelihood. It is shown that the p-wave neutron reduced widths of even-even nuclei fallow single channel Porter Thomas distribution (χ 2 -distribution with degree of freedom ν=1) for most of the cases where there are no intermediate structure. It is emphasized that the distribution in nuclei other than even-even may differ from a χ 2 -distribution with one degree of freedom. Possible explanation and significance of this deviation from ν=1 is given. (author)

Intermediate energy electron cooling for antiproton sources using a Pelletron accelerator

International Nuclear Information System (INIS)

Cline, D.B.; Adney, J.; Ferry, J.; Kells, W.; Larson, D.J.; Mills, F.E.; Sundquist, M.

1983-01-01

It has been shown at FNAL that the electron cooling of protons is a very efficient method for reaching high luminosity in a proton beam. The emittance of the 120 KeV electron beam used at Fermilab corresponds to a cathode temperature of 0.1 eV. In order to apply cooling techniques to GeV proton beams the electron energies required are in the MeV range. In the experiment reported in this paper the emittance of a 3-MeV Pelletron electron accelerator was measured to determine that its emittance scaled to a value appropriate for electron cooling. The machine tested was jointly owned and operated by the University of California at Santa Barbara and National Electrostatics Corporation for research into free-electron lasers which also require low emittance beams for operation. This paper describes the thermal emittance of the beam to be the area in phase space in which 90% of the beam trajectories lie and goes on to describe the emittance-measurement method both in theory and application

Printable Spacecraft: Flexible Electronic Platforms for NASA Missions. Phase One

Science.gov (United States)

Short, Kendra (Principal Investigator); Van Buren, David (Principal Investigator)

2012-01-01

Atmospheric confetti. Inchworm crawlers. Blankets of ground penetrating radar. These are some of the unique mission concepts which could be enabled by a printable spacecraft. Printed electronics technology offers enormous potential to transform the way NASA builds spacecraft. A printed spacecraft's low mass, volume and cost offer dramatic potential impacts to many missions. Network missions could increase from a few discrete measurements to tens of thousands of platforms improving areal density and system reliability. Printed platforms could be added to any prime mission as a low-cost, minimum resource secondary payload to augment the science return. For a small fraction of the mass and cost of a traditional lander, a Europa flagship mission might carry experimental printed surface platforms. An Enceladus Explorer could carry feather-light printed platforms to release into volcanic plumes to measure composition and impact energies. The ability to print circuits directly onto a variety of surfaces, opens the possibility of multi-functional structures and membranes such as "smart" solar sails and balloons. The inherent flexibility of a printed platform allows for in-situ re-configurability for aerodynamic control or mobility. Engineering telemetry of wheel/soil interactions are possible with a conformal printed sensor tape fit around a rover wheel. Environmental time history within a sample return canister could be recorded with a printed sensor array that fits flush to the interior of the canister. Phase One of the NIAC task entitled "Printable Spacecraft" investigated the viability of printed electronics technologies for creating multi-functional spacecraft platforms. Mission concepts and architectures that could be enhanced or enabled with this technology were explored. This final report captures the results and conclusions of the Phase One study. First, the report presents the approach taken in conducting the study and a mapping of results against the proposed

STUTTERING THERAPY FOR A CHILD AT INTERMEDIATE STUTTERING LEVEL

Directory of Open Access Journals (Sweden)

Nevzeta SALIHOVIKJ

2009-11-01

Full Text Available Stuttering therapy very often demands combination of various approaches or its modification. The main purpose of this study was to present an integrated approach to stuttering modification therapy and fluency shaping therapy for an intermediate school-age male stutterer (11 years old.The therapy for the child lasted for 12 months, sessions have been carried out twice a week, each session lasted for 45 minutes. The child still attends the therapy. The therapy uses integration of stuttering modification therapy and fluency shaping therapy. For the purpose of the fluency shaping therapy, delayed auditory feedback program is applied. During the stuttering modification therapy the child has been taught how to stutter more easily which implies prolongation of all sounds in words on which child stutters, with easy and soft transition from one sound to another. It is continuously being worked with the child on reducing negative feelings and attitudes as well as elimination of avoidance of words and speaking situations. We explained to the parents the treatment program and their role in the program realization. We also explained the possible causes of stuttering, and tried to identify and reduce fluency distractors, and engage the child in as many situations as possible which improved speech fluency.After the application of this program the child has improved fluency during the conversation in clinical and nonclinical conditions (environment. This fluency consists of spontaneous and controlled fluency. Furthermore, fear of speaking and avoidance of speech situations are significantly reduced. On the basis of the applied therapy on the child at intermediate stuttering level it can be concluded that it is possible to integrate successfully both approaches: stuttering modification therapy and fluency shaping therapy.

Direct processes in ion-atom collisions at intermediate and high energies

International Nuclear Information System (INIS)

Rodriguez Chariarse, V.D.

1990-01-01

This thesis deals with direct processes induced by Zp charge ion impact on one or two electron atoms and ions at intermediate energies. At a first step, a one-dimensional collision model is used in order to prove the different theoretical methods available to study collisions at such energy range, such as: perturbative and related variational principles, and distorted wave methods. The best description of both, symmetric and asymmetric collision type, is achieved by the distorted wave methods, particularly the ones using the exact impulsive wave function. As a next step, the appropriate formulations of the wave functions employed in the one-dimensional model to describe the real 3-dimensional Coulomb interaction case are examined by using the Eikonal and impulse hypothesis. In this way, the VPS and Eikonal wave functions are reviewed, and furtherly, the Eikonal form of the extended impulse wave function is derived. The Eikonal impulse approximation (EIA) is introduced. This is a distorted wave method using the Eikonal and extended impulse wave functions. The choice of the EIA prior version, i.e., the one using extended impulse wave function in the final channel for excitation is widely discussed and justified. (Author) [es

Pulse-radiolytic one-electron reduction of anthraquinone and chloro-anthraquinones in aqueous-isopropanol-acetone mixed solvent

International Nuclear Information System (INIS)

Rath, M.C.; Pal, H.; Mukherjee, T.

1996-01-01

One-electron reduction of 9,10-anthraquinone and some chloro-anthraquinones and the characteristics of the semiquinones thus formed have been investigated in aqueous-isipropanol-acetone mixed solvent using electron pulse radiolysis technique. Spectroscopic characteristics, kinetic parameters of formation and decay, and the acid/base behaviour of the semiquinones have been investigated. The one-electron reduction potential of the quinones have been measured following electron transfer equilibria with a reference redox system (methyl viologen) and the values thus obtained have been compared with those of some other anthrasemiquinone systems. An analysis of the characteristics of the semiquinones shows that α-chloro substituents adjacent to the C=O group act as electron withdrawing groups. (author)

Covalent functionalization of graphene with reactive intermediates.

Science.gov (United States)

Park, Jaehyeung; Yan, Mingdi

2013-01-15

Graphene, a material made exclusively of sp(2) carbon atoms with its π electrons delocalized over the entire 2D network, is somewhat chemically inert. Covalent functionalization can enhance graphene's properties including opening its band gap, tuning conductivity, and improving solubility and stability. Covalent functionalization of pristine graphene typically requires reactive species that can form covalent adducts with the sp(2) carbon structures in graphene. In this Account, we describe graphene functionalization reactions using reactive intermediates of radicals, nitrenes, carbenes, and arynes. These reactive species covalently modify graphene through free radical addition, CH insertion, or cycloaddition reactions. Free radical additions are among the most common reaction, and these radicals can be generated from diazonium salts and benzoyl peroxide. Electron transfer from graphene to aryl diazonium ion or photoactivation of benzoyl peroxide yields aryl radicals that subsequently add to graphene to form covalent adducts. Nitrenes, electron-deficient species generated by thermal or photochemical activation of organic azides, can functionalize graphene very efficiently. Because perfluorophenyl nitrenes show enhanced bimolecular reactions compared with alkyl or phenyl nitrenes, perfluorophenyl azides are especially effective. Carbenes are used less frequently than nitrenes, but they undergo CH insertion and C═C cycloaddition reactions with graphene. In addition, arynes can serve as a dienophile in a Diels-Alder type reaction with graphene. Further study is needed to understand and exploit the chemistry of graphene. The generation of highly reactive intermediates in these reactions leads to side products that complicate the product composition and analysis. Fundamental questions remain about the reactivity and regioselectivity of graphene. The differences in the basal plane and the undercoordinated edges of graphene and the zigzag versus arm-chair configurations

Local and global properties of eigenfunctions and one-electron densities of Coulombic Schrödinger operators

DEFF Research Database (Denmark)

Fournais, Søren; Hoffmann-Ostenhof, Maria; Hoffmann-Ostenhof, Thomas

2008-01-01

We review recent results by the authors on the regularity of molecular eigenfunctions ψ and their corresponding one-electron densities ρ, as well as of the spherically averaged one-electron atomic density ρ. Furthermore, we prove an exponentially decreasing lower bound for ρ in the case when...

Electron interactions with nuclei: Progress report

International Nuclear Information System (INIS)

1988-08-01

This paper contains information on the following topics: inclusive electron scattering; electroexcitation of Δ in nuclei; longitudinal and transverse response in the quasi-elastic region; electron scattering at MIT-Bates; detector development at LEGS; electron scattering at Saclay; intermediate energy nuclear interactions; research and development at CEBAF; and computing facilities

TYPE Ia SNe ALONG REDSHIFT: THE R(Si II) RATIO AND THE EXPANSION VELOCITIES IN INTERMEDIATE-z SUPERNOVAE

International Nuclear Information System (INIS)

Altavilla, G.; Ruiz-Lapuente, P.; Balastegui, A.; Mendez, J.; Espana-Bonet, C.; Irwin, M.; Ellis, R. S.; McMahon, R. M.; Walton, N. A.; Folatelli, G.; Goobar, A.; Nobili, S.; Stanishev, V.; Hillebrandt, W.

2009-01-01

We present a study of intermediate-z Type Ia supernovae (SNe Ia) using empirical physical diagrams which permit the investigation of those SNe explosions. This information can be very useful to reduce systematic uncertainties of the Hubble diagram of SNe Ia up to high z. The study of the expansion velocities and the measurement of the ratio R(Si II) allow subtyping of SNe Ia as done in nearby samples. The evolution of this ratio as seen in the diagram R(Si II)-(t) together with R(Si II) max versus (B - V) 0 indicates consistency of the properties at intermediate-z compared with the nearby SNe Ia. At intermediate-z, expansion velocities of Ca II and Si II are found similar to those of the nearby sample. This is found in a sample of six SNe Ia in the range 0.033 ≤z≤ 0.329 discovered within the International Time Programme of SNe Ia for Cosmology and Physics in the spring run of 2002. 7 The program run under Omega and Lambda from Supernovae and the Physics of Supernova Explosions within the International Time Programme at the telescopes of the European Northern Observatory (ENO) at La Palma (Canary Islands, Spain). Two SNe Ia at intermediate-z were of the cool FAINT type, one being an SN1986G-like object highly reddened. The R(Si II) ratio as well as subclassification of the SNe Ia beyond templates help to place SNe Ia in their sequence of brightness and to distinguish between reddened and intrinsically red supernovae. This test can be done with very high z SNe Ia and it will help to reduce systematic uncertainties due to extinction by dust. It should allow to map the high-z sample into the nearby one.

Response function and optimum configuration of semiconductor backscattered-electron detectors for scanning electron microscopes

International Nuclear Information System (INIS)

Rau, E. I.; Orlikovskiy, N. A.; Ivanova, E. S.

2012-01-01

A new highly efficient design for semiconductor detectors of intermediate-energy electrons (1–50 keV) for application in scanning electron microscopes is proposed. Calculations of the response function of advanced detectors and control experiments show that the efficiency of the developed devices increases on average twofold, which is a significant positive factor in the operation of modern electron microscopes in the mode of low currents and at low primary electron energies.

Intermediate statistics in quantum maps

Energy Technology Data Exchange (ETDEWEB)

Giraud, Olivier [H H Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Marklof, Jens [School of Mathematics, University of Bristol, University Walk, Bristol BS8 1TW (United Kingdom); O' Keefe, Stephen [School of Mathematics, University of Bristol, University Walk, Bristol BS8 1TW (United Kingdom)

2004-07-16

We present a one-parameter family of quantum maps whose spectral statistics are of the same intermediate type as observed in polygonal quantum billiards. Our central result is the evaluation of the spectral two-point correlation form factor at small argument, which in turn yields the asymptotic level compressibility for macroscopic correlation lengths. (letter to the editor)

Intermediate neutron spectrum problems and the intermediate neutron spectrum experiment

International Nuclear Information System (INIS)

Jaegers, P.J.; Sanchez, R.G.

1996-01-01

Criticality benchmark data for intermediate energy spectrum systems does not exist. These systems are dominated by scattering and fission events induced by neutrons with energies between 1 eV and 1 MeV. Nuclear data uncertainties have been reported for such systems which can not be resolved without benchmark critical experiments. Intermediate energy spectrum systems have been proposed for the geological disposition of surplus fissile materials. Without the proper benchmarking of the nuclear data in the intermediate energy spectrum, adequate criticality safety margins can not be guaranteed. The Zeus critical experiment now under construction will provide this necessary benchmark data

The 1.6 Å crystal structure of pyranose dehydrogenase from Agaricus meleagris rationalizes substrate specificity and reveals a flavin intermediate.

Directory of Open Access Journals (Sweden)

Tien Chye Tan

Full Text Available Pyranose dehydrogenases (PDHs are extracellular flavin-dependent oxidoreductases secreted by litter-decomposing fungi with a role in natural recycling of plant matter. All major monosaccharides in lignocellulose are oxidized by PDH at comparable yields and efficiencies. Oxidation takes place as single-oxidation or sequential double-oxidation reactions of the carbohydrates, resulting in sugar derivatives oxidized primarily at C2, C3 or C2/3 with the concomitant reduction of the flavin. A suitable electron acceptor then reoxidizes the reduced flavin. Whereas oxygen is a poor electron acceptor for PDH, several alternative acceptors, e.g., quinone compounds, naturally present during lignocellulose degradation, can be used. We have determined the 1.6-Å crystal structure of PDH from Agaricus meleagris. Interestingly, the flavin ring in PDH is modified by a covalent mono- or di-atomic species at the C(4a position. Under normal conditions, PDH is not oxidized by oxygen; however, the related enzyme pyranose 2-oxidase (P2O activates oxygen by a mechanism that proceeds via a covalent flavin C(4a-hydroperoxide intermediate. Although the flavin C(4a adduct is common in monooxygenases, it is unusual for flavoprotein oxidases, and it has been proposed that formation of the intermediate would be unfavorable in these oxidases. Thus, the flavin adduct in PDH not only shows that the adduct can be favorably accommodated in the active site, but also provides important details regarding the structural, spatial and physicochemical requirements for formation of this flavin intermediate in related oxidases. Extensive in silico modeling of carbohydrates in the PDH active site allowed us to rationalize the previously reported patterns of substrate specificity and regioselectivity. To evaluate the regioselectivity of D-glucose oxidation, reduction experiments were performed using fluorinated glucose. PDH was rapidly reduced by 3-fluorinated glucose, which has the C2

Regular perturbation theory for two-electron atoms

International Nuclear Information System (INIS)

Feranchuk, I.D.; Triguk, V.V.

2011-01-01

Regular perturbation theory (RPT) for the ground and excited states of two-electron atoms or ions is developed. It is shown for the first time that summation of the matrix elements from the electron-electron interaction operator over all intermediate states can be calculated in a closed form by means of the two-particle Coulomb Green's function constructed in the Letter. It is shown that the second order approximation of RPT includes the main part of the correlation energy both for the ground and excited states. This approach can be also useful for description of two-electron atoms in external fields. -- Highlights: → We develop regular perturbation theory for the two-electron atoms or ions. → We calculate the sum of the matrix elements over all intermediate states. → We construct the two-particle Coulomb Green's function.

Low and intermediate level radioactive waste processing in plasma reactor

International Nuclear Information System (INIS)

Sauchyn, V.; Khvedchyn, I.; Van Oost, G.

2013-01-01

Methods of low and intermediate level radioactive waste processing comprise: cementation, bituminization, curing in polymer matrices, combustion and pyrolysis. All these methods are limited in their application in the field of chemical, morphological, and aggregate composition of material to be processed. The thermal plasma method is one of the universal methods of RAW processing. The use of electric-arc plasma with mean temperatures 2000 - 8000 K can effectively carry out the destruction of organic compounds into atoms and ions with very high speeds and high degree of conversion. Destruction of complex substances without oxygen leads to a decrease of the volume of exhaust gases and dimension of gas cleaning system. This paper presents the plasma reactor for thermal processing of low and intermediate level radioactive waste of mixed morphology. The equipment realizes plasma-pyrolytic conversion of wastes and results in a conditioned product in a single stage. As a result, the volume of conditioned waste is significantly reduced (more than 10 times). Waste is converted into an environmentally friendly form that suits long-term storage. The leaching rate of macro-components from the vitrified compound is less than 1.10 -7 g/(cm 2 .day). (authors)

Enhanced carrier collection efficiency and reduced quantum state absorption by electron doping in self-assembled quantum dot solar cells

Energy Technology Data Exchange (ETDEWEB)

Li, Tian, E-mail: tianlee@umd.edu, E-mail: dage@ece.umd.edu; Dagenais, Mario, E-mail: tianlee@umd.edu, E-mail: dage@ece.umd.edu [Department of Electrical Engineering, University of Maryland, College Park, Maryland 20742 (United States); Lu, Haofeng; Fu, Lan; Tan, Hark Hoe; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia)

2015-02-02

Reduced quantum dot (QD) absorption due to state filling effects and enhanced electron transport in doped QDs are demonstrated to play a key role in solar energy conversion. Reduced QD state absorption with increased n-doping is observed in the self-assembled In{sub 0.5}Ga{sub 0.5}As/GaAs QDs from high resolution below-bandgap external quantum efficiency (EQE) measurement, which is a direct consequence of the Pauli exclusion principle. We also show that besides partial filling of the quantum states, electron-doping produces negatively charged QDs that exert a repulsive Coulomb force on the mobile electrons, thus altering the electron trajectory and reducing the probability of electron capture, leading to an improved collection efficiency of photo-generated carriers, as indicated by an absolute above-bandgap EQE measurement. The resulting redistribution of the mobile electron in the planar direction is further validated by the observed photoluminescence intensity dependence on doping.

Combined electron beam and vacuum ARC melting for barrier tube shell material

International Nuclear Information System (INIS)

Worcester, S.A.; Woods, C.R.

1989-01-01

This patent describes a process of the type wherein zirconium tetrachloride is reduced to produce a metallic zirconium sponge. The sponge is distilled to generally remove residual magnesium and magnesium chloride, and the distilled sponge is melted to produce an ingot, the improvement for making a non-crystal bar material for use in lining the interior of zirconium alloy fuel element cladding which comprises: a. forming the distilled sponge into a consumable electrode; b. melting the consumable electrode in a multiple swept beam electron furnace with a feed rate between 1 and 20 inches per hour to form an intermediate ingot; and c. vacuum arc melting the intermediate ingot to produce a homogeneous final ingot, having 50-500 ppm iron

Calculation of two-center one-electron molecular integrals with STOs. [BICEN

Energy Technology Data Exchange (ETDEWEB)

Rico, J.F.; Lopez, R.; Paniagua, M.; Ramirez, G. (Universidad Autonoma de Madrid (Spain). Dept. de Quimica Fisica y Quimica Cuantica)

1991-05-01

A program for the calculation of two-center one-electron integrals (overlap, nuclear attraction and kinetic energy) between real Slater-type orbitals (STOs) is reported. The integrals are obtained by recursion over simple auxiliary matrices, whose elements are calculated in terms of further auxiliary functions evaluated in a quick and accurate way. (orig.).

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...

One size fits all electronics for insole-based activity monitoring.

Science.gov (United States)

Hegde, Nagaraj; Bries, Matthew; Melanson, Edward; Sazonov, Edward

2017-07-01

Footwear based wearable sensors are becoming prominent in many areas of monitoring health and wellness, such as gait and activity monitoring. In our previous research we introduced an insole based wearable system SmartStep, which is completely integrated in a socially acceptable package. From a manufacturing perspective, SmartStep's electronics had to be custom made for each shoe size, greatly complicating the manufacturing process. In this work we explore the possibility of making a universal electronics platform for SmartStep - SmartStep 3.0, which can be used in the most common insole sizes without modifications. A pilot human subject experiments were run to compare the accuracy between the one-size fits all (SmartStep 3.0) and custom size SmartStep 2.0. A total of ~10 hours of data was collected in the pilot study involving three participants performing different activities of daily living while wearing SmartStep 2.0 and SmartStep 3.0. Leave one out cross validation resulted in a 98.5% average accuracy from SmartStep 2.0, while SmartStep 3.0 resulted in 98.3% accuracy, suggesting that the SmartStep 3.0 can be as accurate as SmartStep 2.0, while fitting most common shoe sizes.

Electron transfer mediators accelerated the microbiologically influence corrosion against carbon steel by nitrate reducing Pseudomonas aeruginosa biofilm.

Science.gov (United States)

Jia, Ru; Yang, Dongqing; Xu, Dake; Gu, Tingyue

2017-12-01

Electron transfer is a rate-limiting step in microbiologically influenced corrosion (MIC) caused by microbes that utilize extracellular electrons. Cross-cell wall electron transfer is necessary to transport the electrons released from extracellular iron oxidation into the cytoplasm of cells. Electron transfer mediators were found to accelerate the MIC caused by sulfate reducing bacteria. However, there is no publication in the literature showing the effect of electron transfer mediators on MIC caused by nitrate reducing bacteria (NRB). This work demonstrated that the corrosion of anaerobic Pseudomonas aeruginosa (PAO1) grown as a nitrate reducing bacterium biofilm on C1018 carbon steel was enhanced by two electron transfer mediators, riboflavin and flavin adenine dinucleotide (FAD) separately during a 7-day incubation period. The addition of either 10ppm (w/w) (26.6μM) riboflavin or 10ppm (12.7μM) FAD did not increase planktonic cell counts, but they increased the maximum pit depth on carbon steel coupons considerably from 17.5μm to 24.4μm and 25.0μm, respectively. Riboflavin and FAD also increased the specific weight loss of carbon steel from 2.06mg/cm 2 to 2.34mg/cm 2 and 2.61mg/cm 2 , respectively. Linear polarization resistance, electrochemical impedance spectroscopy and potentiodynamic polarization curves all corroborated the pitting and weight loss data. Copyright © 2017 Elsevier B.V. All rights reserved.

A hybrid intermediate language between SSA and CPS

DEFF Research Database (Denmark)

Torrens, Paulo; Vasconcellos, Cristiano; Gonçalves, Ju

2017-01-01

passing style (CPS) lambda calculus has been used as intermediate language for functional language compilers, they are (almost) equivalent and it is possible to draw syntactic translations between them. This short paper aims to present an untyped intermediate language which may be interpreted as both SSA...... and CPS, in order to provide a common language for both imperative and functional compilers, as well to take advantage of optimizations designed for either one of the approaches. Finally, potential variants and research opportunities are discussed....

Freeze-quench (57)Fe-Mössbauer spectroscopy: trapping reactive intermediates.

Science.gov (United States)

Krebs, Carsten; Bollinger, J Martin

2009-01-01

(57)Fe-Mössbauer spectroscopy is a method that probes transitions between the nuclear ground state (I=1/2) and the first nuclear excited state (I=3/2). This technique provides detailed information about the chemical environment and electronic structure of iron. Therefore, it has played an important role in studies of the numerous iron-containing proteins and enzymes. In conjunction with the freeze-quench method, (57)Fe-Mössbauer spectroscopy allows for monitoring changes of the iron site(s) during a biochemical reaction. This approach is particularly powerful for detection and characterization of reactive intermediates. Comparison of experimentally determined Mössbauer parameters to those predicted by density functional theory for hypothetical model structures can then provide detailed insight into the structures of reactive intermediates. We have recently used this methodology to study the reactions of various mononuclear non-heme-iron enzymes by trapping and characterizing several Fe(IV)-oxo reaction intermediates. In this article, we summarize these findings and demonstrate the potential of the method. © Springer Science+Business Media B.V. 2009

Brillouin spectroscopy with surface acoustic waves on intermediate valent, doped SmS

International Nuclear Information System (INIS)

Schaerer, U.; Jung, A.; Wachter, P.

1998-01-01

Brillouin scattering on surface acoustic waves is a very powerful tool to determine the elastic constants of intermediate valent crystals, since the method is non-destructive and no mechanical contact is needed. A strong evidence for intermediate valence is a negative value of Poisson's ratio, which describes the behavior of the volume under uniaxial pressure. SmS by itself makes a semiconductor-metal transition at a pressure of more than 6.5 kbar. When substituting the divalent Sm by a trivalent cation, like Y, La or Tm, SmS can become - depending on the doping concentration - intermediate valent without any applied, external pressure. In this work, we will present measurements of the velocities of the surface acoustic waves and the calculation of the elastic constants of La- and Tm-doped SmS compounds. We found a clear dependence of Poisson's ratio on the doping concentration and on the valence of the materials. Furthermore, we will discuss the mechanism leading to intermediate valence when substituting Sm. Besides the internal, chemical pressure, which is produced by the built in trivalent cations with their smaller ionic radii, we have clear evidence, that the free electrons in the 5d band, induced by the substituting atoms, also play an important role in making doped SmS intermediate valent. (orig.)

Perturbation expansion of the ground-state energy for the one-dimensional cyclic Hubbard system in the Hueckel limit

International Nuclear Information System (INIS)

Takahashi, M.; Bracken, P.; Cizek, J.; Paldus, J.

1995-01-01

The perturbation expansion coefficients for the ground-state energy of the half-filled one-dimensional Hubbard model with N = 4 ν + 2, (ν = 1,2,...) sites and satisfying cyclic boundary conditions were calculated in the Hueckel limit (U/β → 0), where β designates the one-electron hopping or resonance integral, and U, the two-electron on-site Coulomb integral. This was achieved by solving-order by order-the Lieb-Wu equations, a system of transcendental equations that determines the set of quasi-momenta (k i ) and spin variable τ α for this model. The exact values for these quantities were found for the N = 6 member ring up to the 20th order in terms of the coupling constant B = U/2β, as well as numerically for 10 ≤ N ≤ 50, and the N = 6 Lieb-Wu system was reduced to a system of sextic algebraic equations. These results are compared with those of the infinite system derived analytically by Misurkin and Ovchinnikov. It is further shown how the results of this article can be used for the interpolation by the root of a polynomial. It is demonstrated that a polynomial of relatively small degree provides a very good approximation for the energy in the intermediate coupling region. 20 refs., 3 tabs

One-electron oxidation of BD84, an ellipticine antitumor derivative

International Nuclear Information System (INIS)

Sekaki, A.; Gardes-Albert, M.; Houee-Levin, C.; Ferradini, C.; Rivalle, C.; Bisagni, E.; Hickel, B.

1991-01-01

The one-electron oxidation of BD84, an ellipticine-related drug, has been studied by pulse radiolysis using OH· radicals as oxidizing agents. In the absence of oxygen, R· radicals are formed. They disappear by recombination. In the presence of oxygen, R· radicals react with O 2 to give peroxy radicals RO 2 ·, which decay by a second-order process. These results are compared to those obtained for other ellipticine derivatives [fr

Carbon emission, energy consumption and intermediate goods trade: A regional study of East Asia

International Nuclear Information System (INIS)

Zhang, Jingjing

2015-01-01

Using country level panel data from East Asia over the period 1998–2011, this paper examines the implications of international production fragmentation-induced intermediate goods trade on the link between energy consumption and carbon pollution. The paper focuses on the interaction effect between energy consumption and trade in intermediate goods on carbon emission. The empirical results presented suggest that international trade in intermediate goods decreases the positive impact on carbon emission of energy consumption. When compared with the trade in final goods, intermediate goods trade contributes to a greater decrease in carbon pollution resulting from energy consumption. These results confirm that the link between energy consumption and carbon pollution in East Asia is significantly affected by international production fragmentation-induced trade in intermediate goods. The results presented in this paper have some important policy implications. - Highlights: • This paper tests the role of intermediates trade in energy-development nexus. • Empirical study is based on data of East Asia. • International trade can reduce the carbon pollution caused by energy use. • Intermediates trade has higher moderating effect than non-intermediate trade.

CP-even and CP-odd transverse polarization of the electron in the muon decay

International Nuclear Information System (INIS)

Kuznetsov, A.V.

1981-01-01

In the most general weak interaction model with intermediate vector bosons, allowing CP breaking in the muon decay, CP- even and CP-odd transverse polarization of the μ-decay electrons is calculated taking into account the radiative corrections. It is shown that such corrections are essential only at the beginning of the spectrum reducing the observed transverse polarization effects. When the electron energy is close to its maximum and the emission angles are small, the transverse polarization considerably grows. Search for CP-even and CP-odd transverse polarization of the electrons should be carried out at energies Esub(e) approximately equal to O.975 Esub(e)sup(max) and emission angles THETA approximately equal to 25+35 deg [ru

One-dimensional electron liquid at a surface. Gold nanowires on Ge(001)

Energy Technology Data Exchange (ETDEWEB)

Blumenstein, Christian

2012-09-11

Self-organized nanowires at semiconductor surfaces offer the unique opportunity to study electrons in reduced dimensions. Notably the dimensionality of the system determines it's electronic properties, beyond the quasiparticle description. In the quasi-one-dimensional (1D) regime with weak lateral coupling between the chains, a Peierls instability can be realized. A nesting condition in the Fermi surface leads to a backfolding of the 1D electron band and thus to an insulating state. It is accompanied by a charge density wave (CDW) in real space that corresponds to the nesting vector. This effect has been claimed to occur in many surface-defined nanowire systems, such as the In chains on Si(111) or the Au reconstructions on the terraced Si(553) and Si(557) surfaces. Therefore a weak coupling between the nanowires in these systems has to be concluded. However theory proposes another state in the perfect 1D limit, which is completely destroyed upon slight coupling to higher dimensions. In this so-called Tomonaga-Luttinger liquid (TLL) state, the quasiparticle description of the Fermi liquid breaks down. Since the interaction between the electrons is enhanced due to the strong confinement, only collective excitations are allowed. This leads to novel effects like spin charge separation, where spin and charge degrees of freedom are decoupled and allowed to travel independently along the 1D-chain. Such rare state has not been realized at a surface until today. This thesis uses a novel approach to realize nanowires with improved confinement by studying the Au reconstructed Ge(001) surface. A new cleaning procedure using piranha solution is presented, in order to prepare a clean and long-range ordered substrate. To ensure optimal growth of the Au nanowires the phase diagram is extensively studied by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). The structural elements of the chains are revealed and described in high detail. Remarkably

Intermediate energy cross sections for electron-impact vibrational-excitation of pyrimidine

Energy Technology Data Exchange (ETDEWEB)

Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Ellis-Gibbings, L.; García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); Nixon, K. L. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); School of Biology, Chemistry and Forensic Science, University of Wolverhampton, Wolverhampton WV1 1LY (United Kingdom); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2015-09-07

We report differential cross sections (DCSs) and integral cross sections (ICSs) for electron-impact vibrational-excitation of pyrimidine, at incident electron energies in the range 15–50 eV. The scattered electron angular range for the DCS measurements was 15°–90°. The measurements at the DCS-level are the first to be reported for vibrational-excitation in pyrimidine via electron impact, while for the ICS we extend the results from the only previous condensed-phase study [P. L. Levesque, M. Michaud, and L. Sanche, J. Chem. Phys. 122, 094701 (2005)], for electron energies ⩽12 eV, to higher energies. Interestingly, the trend in the magnitude of the lower energy condensed-phase ICSs is much smaller when compared to the corresponding gas phase results. As there is no evidence for the existence of any shape-resonances, in the available pyrimidine total cross sections [Baek et al., Phys. Rev. A 88, 032702 (2013); Fuss et al., ibid. 88, 042702 (2013)], between 10 and 20 eV, this mismatch in absolute magnitude between the condensed-phase and gas-phase ICSs might be indicative for collective-behaviour effects in the condensed-phase results.

Electronic behavior of highly correlated metals

International Nuclear Information System (INIS)

Reich, A.

1988-10-01

This thesis addresses the question of the strongly interacting many-body problem: that is, systems where the interparticle correlations are so strong as to defy perturbative approaches. These subtle correlations occur in narrow band materials, such as the lanthanides and actinides, wherein the f-electrons are so localized that a variety of new phenomena, including intermediate-valence and heavy-fermionic behavior, may occur. As well, one has the alloying problem, where local interactions are paramount in determining the overall behavior. The technique employed in dealing with these systems is the Small Cluster method, wherein the full many-body Hamiltonian for a small grouping of atoms, coupled with periodic boundary conditions, is solved exactly. This is tantamount to solving a bulk crystal at the high points of symmetry in the Brillouin Zone. The mathematical overhead is further reduced by employing the full space group and spin symmetries. By its very nature, the Small Cluster method is well able to handle short-range interactions, as well as the combinatorial complexity of the many-body problem, on an equal footing. The nature of long-range order and phase transition behavior cannot be incorporated, but sometimes clues as to their origin can be discerned. The calculations presented include: a two-band Anderson model for an intermediate-valence system, wherein photoemission and fluctuation behavior is examined; a single-band Hubbard model for a ternary alloy system, such as copper-silver-gold; and a Hubbard model for a heavy- fermion system, wherein Fermi surface, transport, magnetic and superconducting properties are discussed. 148 refs., 31 figs., 24 tabs

Hydride vapor phase GaN films with reduced density of residual electrons and deep traps

International Nuclear Information System (INIS)

Polyakov, A. Y.; Smirnov, N. B.; Govorkov, A. V.; Yugova, T. G.; Cox, H.; Helava, H.; Makarov, Yu.; Usikov, A. S.

2014-01-01

Electrical properties and deep electron and hole traps spectra are compared for undoped n-GaN films grown by hydride vapor phase epitaxy (HVPE) in the regular process (standard HVPE samples) and in HVPE process optimized for decreasing the concentration of residual donor impurities (improved HVPE samples). It is shown that the residual donor density can be reduced by optimization from ∼10 17  cm −3 to (2–5) × 10 14  cm −3 . The density of deep hole traps and deep electron traps decreases with decreased donor density, so that the concentration of deep hole traps in the improved samples is reduced to ∼5 × 10 13  cm −3 versus 2.9 × 10 16  cm −3 in the standard samples, with a similar decrease in the electron traps concentration

Studies of collision dynamics in electron capture processes

International Nuclear Information System (INIS)

Hansen, J.P.

1990-12-01

This thesis presents some recent development in time-dependent coupled channel methods for one- and two-electron systems. The methods have been applied to detailed studies on several different aspects of charge transfer processes in ion-atom collisions at intermediate to low energies. Measurable quantities, such as partial and total cross sections, partial cross sections in projectile energy gain, orientation and alignment fractions, have been calculated. Confrontation with experiments has in general given good agreement. 29 refs

Studies of collision dynamics in electron capture processes

International Nuclear Information System (INIS)

Hansen, J.P.

1989-12-01

The thesis presents some recent development in time-dependent coupled channel methods for one- and two-electron systems. The methods have been applied to detailed studies on several different aspects of charge transfer processes in ion-atom collisions at intermediate to low energies. Measurable quantities, such as partial and total cross sections, partial cross sections in projectile energy gain, orientation and alignment fractions, have been calculated. Confrontation with experiments has in general given good agreement. 14 refs., 2 figs

C and C* among intermediate rings

NARCIS (Netherlands)

Sack, J.; Watson, S.

2014-01-01

Given a completely regular Hausdorff space X, an intermediate ring A(X) is a ring of real valued continuous functions between C*(X) and C(X). We discuss two correspondences between ideals in A(X) and z-filters on X, both reviewing old results and introducing new results. One correspondence, ZA,

Mtr Extracellular Electron Transfer Pathways in Fe(III)-reducing or Fe(II)-oxidizing Bacteria: A Genomic Perspective

Energy Technology Data Exchange (ETDEWEB)

Shi, Liang; Rosso, Kevin M.; Zachara, John M.; Fredrickson, Jim K.

2012-12-01

Originally discovered in the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1 (MR-1), the Mtr (i.e., metal-reducing) pathway exists in all characterized strains of metal-reducing Shewanella. The protein components identified to date for the Mtr pathway of MR-1 include four multi-heme c-type cytochromes (c-Cyts), CymA, MtrA, MtrC and OmcA, and a porin-like, outer membrane protein MtrB. They are strategically positioned along the width of the MR-1 cell envelope to mediate electron transfer from the quinone/quinol pool in the inner-membrane to the Fe(III)-containing minerals external to the bacterial cells. A survey of microbial genomes revealed homologues of the Mtr pathway in other dissimilatory Fe(III)-reducing bacteria, including Aeromonas hydrophila, Ferrimonas balearica and Rhodoferax ferrireducens, and in the Fe(II)-oxidizing bacteria Dechloromonas aromatica RCB, Gallionella capsiferriformans ES-2 and Sideroxydans lithotrophicus ES-1. The widespread distribution of Mtr pathways in Fe(III)-reducing or Fe(II)-oxidizing bacteria emphasizes the importance of this type of extracellular electron transfer pathway in microbial redox transformation of Fe. Their distribution in these two different functional groups of bacteria also emphasizes the bi-directional nature of electron transfer reactions carried out by the Mtr pathways. The characteristics of the Mtr pathways may be shared by other pathways used by microorganisms for exchanging electrons with their extracellular environments.

Deep and intermediate mediterranean water in the western Alboran Sea

Science.gov (United States)

Parrilla, Gregorio; Kinder, Thomas H.; Preller, Ruth H.

1986-01-01

Hydrographic and current meter data, obtained during June to October 1982, and numerical model experiments are used to study the distribution and flow of Mediterranean waters in the western Alboran Sea. The Intermediate Water is more pronounced in the northern three-fourths of the sea, but its distribution is patchy as manifested by variability of the temperature and salinity maxima at scales ≤10 km. Current meters in the lower Intermediate Water showed mean flow toward the Strait at 2 cm s -1. A reversal of this flow lasted about 2 weeks. A rough estimate of the mean westward Intermediate Water transport was 0.4 × 10 6 m 3 s -1, about one-third of the total outflow, so that the best estimates of the contributions of traditionally defined Intermediate Water and Deep Water account for only about one-half of the total outflow. The Deep Water was uplifted against the southern continental slope from Alboran Island (3°W) to the Strait. There was also a similar but much weaker banking against the Spanish slope, but a deep current record showed that the eastward recirculation implied by this banking is probably intermittent. Two-layer numerical model experiments simulated the Intermediate Water flow with a flat bottom and the Deep Water with realistic bottom topography. Both experiments replicated the major circulation features, and the Intermediate Water flow was concentrated in the north because of rotation and the Deep Water flow in the south because of topographic control.

Intermediate energy electron impact excitation of composite vibrational modes in phenol

Energy Technology Data Exchange (ETDEWEB)

Neves, R. F. C. [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Instituto Federal do Sul de Minas Gerais, Campus Poços de Caldas, Minas Gerais (Brazil); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, Minas Gerais (Brazil); Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Lopes, M. C. A.; Nixon, K. L. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, Minas Gerais (Brazil); Oliveira, E. M. de; Lima, M. A. P. [Instituto de Física ‘Gleb Wataghin,’ Universidade Estadual de Campinas, 13083-859 Campinas, São Paulo (Brazil); Costa, R. F. da [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, 09210-580 Santo André, São Paulo (Brazil); Varella, M. T. do N. [Instituto de Física, Universidade de São Paulo, C.P. 66318, 05315-970 São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, C.P. 19044, 81531-990 Curitiba, Paraná (Brazil); Silva, G. B. da [Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2015-05-21

We report differential cross section results from an experimental investigation into the electron impact excitation of a number of the low-lying composite (unresolved) vibrational modes in phenol (C{sub 6}H{sub 5}OH). The measurements were carried out at incident electron energies in the range 15–40 eV and for scattered-electron angles in the range 10–90°. The energy resolution of those measurements was typically ∼80 meV. Calculations, using the GAMESS code, were also undertaken with a B3LYP/aug-cc-pVDZ level model chemistry, in order to enable us to assign vibrational modes to the features observed in our energy loss spectra. To the best of our knowledge, the present cross sections are the first to be reported for vibrational excitation of the C{sub 6}H{sub 5}OH molecule by electron impact.

Lean manufacturing implementation in reducing waste for electronic assembly line

Directory of Open Access Journals (Sweden)

Zakaria Nurul Husna

2017-01-01

Full Text Available Lean manufacturing is the most convenient way to eliminate unnecessary waste and can provide what customers demand. This paper presents possibilities and sustainability of application of lean manufacturing method by using a virtual simulation of the workers performance in a line production of small and medium industry. Actual case study and Witness simulation were used in this study to find the waste that exists in the production and identified the performance of workers in the production line. Lean manufacturing concept has identified and rectified problems related to low productivity in the assembly line. The case study is involved a line production for electronic part assembly. The result of this preliminary study should illustrate the relationship of worker’s performance by lean manufacturing method as well as the productivity improvements which help to reduce cost for manufacturer. Lean manufacturing method has been used during the study to reduce the cost when waste is eliminated by reducing the workstation without reducing the performance of the production. The performance of the production is increased when allocating the labor in a needed working area. Lastly, the study also proves that the new layout has improved the process to be used for future production process.

Differential cross sections for intermediate-energy electron scattering from α-tetrahydrofurfuryl alcohol: Excitation of electronic-states

Energy Technology Data Exchange (ETDEWEB)

Chiari, L.; Jones, D. B.; Thorn, P. A.; Pettifer, Z. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Silva, G. B. da [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Limão-Vieira, P. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Duflot, D. [Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, Université Lille, F-59655 Villeneuve d’Ascq Cedex (France); Hubin-Franskin, M.-J.; Delwiche, J. [Départment de Chimie, Université de Liège, Institut de Chimie-Bât. B6C, B-4000 Liège 1 (Belgium); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid E-28040 (Spain); García, G. [Instituto de Física Fundamental, CSIC, Madrid E-28006 (Spain); and others

2014-07-14

We report on measurements of differential cross sections (DCSs) for electron impact excitation of a series of Rydberg electronic-states in α-tetrahydrofurfuryl alcohol (THFA). The energy range of these experiments was 20–50 eV, while the scattered electron was detected in the 10°–90° angular range. There are currently no other experimental data or theoretical computations against which we can directly compare the present measured results. Nonetheless, we are able to compare our THFA DCSs with earlier cross section measurements for Rydberg-state electronic excitation for tetrahydrofuran, a similar cyclic ether, from Do et al. [J. Chem. Phys. 134, 144302 (2011)]. In addition, “rotationally averaged” elastic DCSs, calculated using our independent atom model with screened additivity rule correction approach are also reported. Those latter results give integral cross sections consistent with the optical theorem, and supercede those from the only previous study of Milosavljević et al. [Eur. Phys. J. D 40, 107 (2006)].

CP-even and CP-odd transverse polarization of the electron in muon decay

International Nuclear Information System (INIS)

Kuznetsov, A.

1981-01-01

A model of the weak interaction which contains intermediate vector bosons of the most general form and which admits CP violation in muon decay is used to calculate the CP-even and CP-odd transverse polarization of the μ-decay electrons with inclusion of radiative corrections. It is shown that these corrections are important only at the beginning of the spectrum, and their contribution reduces the observed effects of the transverse polarization. The transverse polarization grows appreciably at electron energies close to the maximum energy and at small emission angles. It is expedient to search for the CP-even and CP-odd transverse polarization of the electrons at energies E/sub e/ = 0.975E/sup max//sub e/ and emission angles theta = 25--35 0

Highly active bidirectional electron transfer by a self-assembled electroactive reduced-graphene-oxide-hybridized biofilm.

Science.gov (United States)

Yong, Yang-Chun; Yu, Yang-Yang; Zhang, Xinhai; Song, Hao

2014-04-22

Low extracellular electron transfer performance is often a bottleneck in developing high-performance bioelectrochemical systems. Herein, we show that the self-assembly of graphene oxide and Shewanella oneidensis MR-1 formed an electroactive, reduced-graphene-oxide-hybridized, three-dimensional macroporous biofilm, which enabled highly efficient bidirectional electron transfers between Shewanella and electrodes owing to high biomass incorporation and enhanced direct contact-based extracellular electron transfer. This 3D electroactive biofilm delivered a 25-fold increase in the outward current (oxidation current, electron flux from bacteria to electrodes) and 74-fold increase in the inward current (reduction current, electron flux from electrodes to bacteria) over that of the naturally occurring biofilms. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Isoporphyrin Intermediate in Heme Oxygenase Catalysis

Science.gov (United States)

Evans, John P.; Niemevz, Fernando; Buldain, Graciela; de Montellano, Paul Ortiz

2008-01-01

Human heme oxygenase-1 (hHO-1) catalyzes the O2- and NADPH-dependent oxidation of heme to biliverdin, CO, and free iron. The first step involves regiospecific insertion of an oxygen atom at the α-meso carbon by a ferric hydroperoxide and is predicted to proceed via an isoporphyrin π-cation intermediate. Here we report spectroscopic detection of a transient intermediate during oxidation by hHO-1 of α-meso-phenylheme-IX, α-meso-(p-methylphenyl)-mesoheme-III, and α-meso-(p-trifluoromethylphenyl)-mesoheme-III. In agreement with previous experiments (Wang, J., Niemevz, F., Lad, L., Huang, L., Alvarez, D. E., Buldain, G., Poulos, T. L., and Ortiz de Montellano, P. R. (2004) J. Biol. Chem. 279, 42593–42604), only the α-biliverdin isomer is produced with concomitant formation of the corresponding benzoic acid. The transient intermediate observed in the NADPH-P450 reductase-catalyzed reaction accumulated when the reaction was supported by H2O2 and exhibited the absorption maxima at 435 and 930 nm characteristic of an isoporphyrin. Product analysis by reversed phase high performance liquid chromatography and liquid chromatography electrospray ionization mass spectrometry of the product generated with H2O2 identified it as an isoporphyrin that, on quenching, decayed to benzoylbiliverdin. In the presence of H218O2, one labeled oxygen atom was incorporated into these products. The hHO-1-isoporphyrin complexes were found to have half-lives of 1.7 and 2.4 h for the p-trifluoromethyl- and p-methyl-substituted phenylhemes, respectively. The addition of NADPH-P450 reductase to the H2O2-generated hHO-1-isoporphyrin complex produced α-biliverdin, confirming its role as a reaction intermediate. Identification of an isoporphyrin intermediate in the catalytic sequence of hHO-1, the first such intermediate observed in hemoprotein catalysis, completes our understanding of the critical first step of heme oxidation. PMID:18487208

Dynamics in ion-molecule collisions at high velocities: One- and two-electron processes

International Nuclear Information System (INIS)

Wang, Yudong.

1992-01-01

This dissertation addresses the dynamic interactions in ion-molecule collisions. Theoretical methods are developed for single and multiple electron transitions in fast collisions with diatomic molecules by heavy-ion projectiles. Various theories and models are developed to treat the three basic inelastic processes (excitation, ionization and charge transfer) involving one and more electrons. The development, incorporating the understanding of ion-atom collision theories with some unique characteristics for molecular targets, provides new insights into phenomena that are absent from collisions with atomic targets. The influence from the multiple scattering centers on collision dynamics is assessed. For diatomic molecules, effects due to a fixed molecular orientation or alignment are calculated and compared with available experimental observations. Compared with excitation and ionization, electron capture, which probes deeper into the target, presents significant two-center interference and strong orientation dependence. Attention has been given in this dissertation to exploring mechanisms for two-and multiple electron transitions. Application of independent electron approximation to transfer excitation from molecular hydrogen is studied. Electron-electron interaction originated from projectile and target nuclear centers is studied in conjunction with the molecular nature of target. Limitations of the present theories and models as well as possible new areas for future theoretical and experimental applications are also discussed. This is the first attempt to describe multi-electron processes in molecular dynamics involving fast highly charged ions

Mechanisms of electron transfer from structrual Fe(II) in reduced nontronite to oxygen for production of hydroxyl radicals

Science.gov (United States)

Yuan, Songhu; Liu, Xixiang; Liao, Wenjuan; Zhang, Peng; Wang, Xiaoming; Tong, Man

2018-02-01

Production of hydroxyl radicals (radOH) has been recently revealed upon oxygenation of sediments in redox-dynamic subsurface environments. In particular, Fe(II)-bearing clay minerals are the major sediment components contributing to radOH production upon oxygenation, and the produced radOH can oxidize contaminants and inactivate bacteria. Whereas, the mechanisms of radOH production from oxygenation of Fe(II)-bearing clay minerals remain elusive. The objectives of this study were to identify the structural variation of Fe(II) entities during the oxidation of Fe(II)-bearing clay minerals by O2, and to unravel the mechanisms of electron transfer within the mineral structure and from mineral to O2 for radOH production. Nontronite (NAu-2, 23% Fe) which was chemically reduced to 54.5% Fe(II) in total Fe was used as a model Fe(II)-bearing clay mineral. Production of radOH and oxidation of Fe(II) were measured during the oxidation of reduced NAu-2 by O2. A wide spectrum of spectroscopic techniques, including Fourier transform infrared spectroscopy (FTIR), Fe K-edge X-ray absorption spectroscopy (XAS), Mössbauer spectra, and X-ray photoelectron spectroscopy (XPS), were employed to explore the structural variation of Fe(II) entities in NAu-2 and the electron transfer within NAu-2 and from NAu-2 to O2. For 180 min oxidation of 1 g/L reduced NAu-2, a biphasic radOH production was observed, being quick within the initial 15 min and slow afterwards. Production of radOH correlates well with oxidation of Fe(II) in the reduced NAu-2. Within the initial 15 min, trioctahedral Fe(II)-Fe(II)-Fe(II) entities and edge Fe(II) in the reduced NAu-2 were preferentially and quickly oxidized, and electrons from the interior Fe(II)-Fe(II)-Fe(II) entities were most likely ejected from the basal siloxane plane to O2. Meanwhile, trioctahedral Fe(II)-Fe(II)-Fe(II) entities were mainly transformed to dioctahedral Fe(II)-Fe(II) entities. When the time of oxygenation was longer than 15 min

Probabilistic assessment of steel moment frames incremental collapse (ordinary, intermediate and special under earthquake

Directory of Open Access Journals (Sweden)

Kourosh Mehdizadeh

2017-11-01

Full Text Available Building collapse is a level of the structure performance in which the amount of financial and life loss is maximized, so this event could be the worst incident in the construction. Regarding to the possibility of destructive earthquakes in different parts of the world, detailed assessment of the structure's collapse has been one of the major challenges of the structural engineering. In this regard, offering models based on laboratory studies, considering the effective parameters and appropriate earthquakes could be a step towards achieving this goal. In this research, a five-story steel structure with a system of ordinary, intermediate and special moment frame (low, intermediate and high ductility has been designed based on the local regulations. In this study, the effect of resistance and stiffness deterioration of the structural elements based on the results of the laboratory models have been considered and the ductility role in the collapse capacity of steel moment frames has been investigated as probabilistic matter. For this purpose, incremental dynamic analysis has been done under 50 pairs of earthquake records proposing FEMA P695 instruction and fragility curves of various performance levels are developed. Results showed higher collapse capacity of special moment steel frame than the intermediate and ordinary moment frames. In the 50 percent probability level, the collapse capacity of special moment frame increased 34 % compared to the intermediate moment frame and 66 % to the ordinary moment frame. Also, the results showed that for different collapse spectral accelerations, the use of special moment frame instead of intermediate and ordinary moment frames reduces the collapse probability to 30 and 50 % respectively.

Superconducting correlations in the one-band Hubbard model with intermediate on-site and weak attractive intersite interactions

International Nuclear Information System (INIS)

Jain, K.P.; Ramakumar, R.; Chancey, C.C.

1990-01-01

In this paper, we analyze a simple extended Hubbard model with an intermediate on-site interaction (both repulsive and attractive) and a weak intersite attractive interaction. Following Hubbard decoupling approximations and introducing Hubbard subband operators, we obtain a generalized gap function for singlet s-wave pairing that explicitly depends on the Hubbard subband energies. For the on-site repulsive-interaction case, we find that the superconductivity is not destroyed in the intermediate-interaction regime, contrary to the prediction of a Hartree-Fock mean-field treatment. The essential consequence of the on-site repulsion is the formation of the Hubbard subbands separated by the Mott-Hubbard gap, and it is within these subbands that pairing induced by the intersite interaction occurs. For the attractive on-site interaction case, the on-site pairing amplitude is found to be proportional to the bandwidth, and the gap function has contributions from both on-site and intersite pairing. The relevance of the model to high-temperature superconductivity is discussed

Microbial Anaerobic Ammonium Oxidation Under Iron Reducing Conditions, Alternative Electron Acceptors

Science.gov (United States)

Ruiz-Urigüen, M.; Jaffe, P. R.

2015-12-01

Autotrophic Acidimicrobiaceae-bacterium named A6 (A6), part of the Actinobacteria phylum have been linked to anaerobic ammonium (NH4+) oxidation under iron reducing conditions. These organisms obtain their energy by oxidizing NH4+ and transferring the electrons to a terminal electron acceptor (TEA). Under environmental conditions, the TEAs are iron oxides [Fe(III)], which are reduced to Fe(II), this process is known as Feammox. Our studies indicate that alternative forms of TEAs can be used by A6, e.g. iron rich clays (i.e. nontronite) and electrodes in bioelectrochemical systems such as Microbial Electrolysis Cells (MECs), which can sustain NH4+removal and A6 biomass production. Our results show that nontronite can support Feammox and promote bacterial cell production. A6 biomass increased from 4.7 x 104 to 3.9 x 105 cells/ml in 10 days. Incubations of A6 in nontronite resulted in up to 10 times more NH4+ removal and 3 times more biomass production than when ferrihydrite is used as the Fe(III) source. Additionally, Fe in nontronite can be reoxidized by aeration and A6 can reutilize it; however, Fe is still finite in the clay. In contrast, in MECs, A6 harvest electrons from NH4+ and use an anode as an unlimited TEA, as a result current is produced. We operated multiple MECs in parallel using a single external power source, as described by Call & Logan (2011). MECs were run with an applied voltage of 0.7V and different growing mediums always containing initial 5mM NH4+. Results show that current production is favored when anthraquinone-2,6-disulfonate (AQDS), an electron shuttled, is present in the medium as it facilitates the transfer of electrons from the bacterial cell to the anode. Additionally, A6 biomass increased from 1 x 104 to 9.77 x 105cells/ml in 14 days of operation. Due to Acidimicrobiaceae-bacterium A6's ability to use various TEAs, MECs represent an alternative, iron-free form, for optimized biomass production of A6 and its application in NH4

Intermediality and media change

OpenAIRE

2012-01-01

This book is about intermediality as an approach to analysing and understanding media change. Intermediality and Media Change is critical of technological determinism that characterises 'new media discourse' about the ongoing digitalization, framed as a revolution and creating sharp contrasts between old and new media. Intermediality instead emphasises paying attention to continuities between media of all types and privileges a comparative perspective on technological changes in media over ti...

Stern-Gerlach experiment, electron spin and intermediate quantum mechanics

Energy Technology Data Exchange (ETDEWEB)

Mackintosh, A.R. (Copenhagen Univ. (Denmark). H.C. Oersted Inst.)

1983-01-01

The paper deals with the theory of electron spin. The Stern-Gerlach experiment, the anticommutation relations and the properties of spin operators are discussed. The Pauli theory, Dirac transformation theory, the double Stern-Gerlach experiment, the EPR paradox and Bell's inequality are also covered.

Utilization of polymer enclosed intermediate class arresters to improve the performance of modern power systems

International Nuclear Information System (INIS)

Sakich, J.D.; Lenk, D.W.; Koepfinger, J.L.

1992-01-01

This paper introduces the first commercially available polymer enclosed intermediate class metal oxide surge arrester. It describes the unique construction of the design, including reduced size, increased flexibility, a collared seal on the polymer housing and an open webbed fiberglass-epoxy module which houses the metal oxide disc elements. Performance advantages are discussed. These include improved short term contamination performance of the insulator-like polymer design when compared to multi-unit porcelain housed designs. Data will show that polymer housed open-webbed fiberglass module construction extends the pressure relief capability beyond that of typical porcelain enclosed designs. The capability of the polymer enclosed design to withstand repeated pressure relief tests, simulating system reclose on a failed arrester, is also discussed. This paper discusses the circumstances at one utility which has considered utilizing polymer enclosed intermediate class arresters to effectively upgrade their system protection capabilities

Reducing statistics anxiety and enhancing statistics learning achievement: effectiveness of a one-minute strategy.

Science.gov (United States)

Chiou, Chei-Chang; Wang, Yu-Min; Lee, Li-Tze

2014-08-01

Statistical knowledge is widely used in academia; however, statistics teachers struggle with the issue of how to reduce students' statistics anxiety and enhance students' statistics learning. This study assesses the effectiveness of a "one-minute paper strategy" in reducing students' statistics-related anxiety and in improving students' statistics-related achievement. Participants were 77 undergraduates from two classes enrolled in applied statistics courses. An experiment was implemented according to a pretest/posttest comparison group design. The quasi-experimental design showed that the one-minute paper strategy significantly reduced students' statistics anxiety and improved students' statistics learning achievement. The strategy was a better instructional tool than the textbook exercise for reducing students' statistics anxiety and improving students' statistics achievement.

Intermediate Fragment

DEFF Research Database (Denmark)

Kruse Aagaard, Anders

2015-01-01

This text and its connected exhibition are aiming to reflect both on the thoughts, the processes and the outcome of the design and production of the artefact ‘Intermediate Fragment’ and making as a contemporary architectural tool in general. Intermediate Fragment was made for the exhibition ‘Enga...... of realising an exhibition object was conceived, but expanded, refined and concretised through this process. The context of the work shown here is an interest in a tighter, deeper connection between experimentally obtained material knowledge and architectural design....

The use of intermediate electron acceptors to enhance MTT bioreduction in a microculture tetrazolium assay for human growth hormone.

Science.gov (United States)

Goodwin, C J; Holt, S J; Downes, S; Marshall, N J

1996-01-01

We contrast the effects of three intermediate electron acceptors (IEAs) on the highly quantitative ESTA bioassay for human growth hormone. This is a microculture tetrazolium assay based upon the in vitro reduction of the tetrazolium salt MTT, by Nb2 cells which have been activated with hGH. Each of the IEAs influenced MTT-formazan production in a distinctive manner. The two quinonoids, namely menadione and co-enzyme Q0 markedly increased the MTT-formazan produced by hormone activated Nb2 cells and thereby amplified the response of our bioassay for human growth hormone (hGH). The exceptionally low bioassay baseline which is characteristic of the unstimulated Nb2 cells when only MTT is added was retained in the presence of CoQ0, but was greatly increased by menadione. Phenazine methosulphate, which is the most widely used redox intermediary in microculture tetrazolium assays, also increased the baseline, but had only a minimal additional effect on MTT reduction by activated Nb2 cells. We conclude that CoQ0 is the preferred IEA for this ESTA bioassay for hGH.

Analytical local electron-electron interaction model potentials for atoms

International Nuclear Information System (INIS)

Neugebauer, Johannes; Reiher, Markus; Hinze, Juergen

2002-01-01

Analytical local potentials for modeling the electron-electron interaction in an atom reduce significantly the computational effort in electronic structure calculations. The development of such potentials has a long history, but some promising ideas have not yet been taken into account for further improvements. We determine a local electron-electron interaction potential akin to those suggested by Green et al. [Phys. Rev. 184, 1 (1969)], which are widely used in atom-ion scattering calculations, electron-capture processes, and electronic structure calculations. Generalized Yukawa-type model potentials are introduced. This leads, however, to shell-dependent local potentials, because the origin behavior of such potentials is different for different shells as has been explicated analytically [J. Neugebauer, M. Reiher, and J. Hinze, Phys. Rev. A 65, 032518 (2002)]. It is found that the parameters that characterize these local potentials can be interpolated and extrapolated reliably for different nuclear charges and different numbers of electrons. The analytical behavior of the corresponding localized Hartree-Fock potentials at the origin and at long distances is utilized in order to reduce the number of fit parameters. It turns out that the shell-dependent form of Green's potential, which we also derive, yields results of comparable accuracy using only one shell-dependent parameter

One-electron oxidation reactions of purine and pyrimidine bases in cellular DNA.

Science.gov (United States)

Cadet, Jean; Wagner, J Richard; Shafirovich, Vladimir; Geacintov, Nicholas E

2014-06-01

The aim of this survey is to critically review the available information on one-electron oxidation reactions of nucleobases in cellular DNA with emphasis on damage induced through the transient generation of purine and pyrimidine radical cations. Since the indirect effect of ionizing radiation mediated by hydroxyl radical is predominant in cells, efforts have been made to selectively ionize bases using suitable one-electron oxidants that consist among others of high intensity UVC laser pulses. Thus, the main oxidation product in cellular DNA was found to be 8-oxo-7,8-dihydroguanine as a result of direct bi-photonic ionization of guanine bases and indirect formation of guanine radical cations through hole transfer reactions from other base radical cations. The formation of 8-oxo-7,8-dihydroguanine and other purine and pyrimidine degradation products was rationalized in terms of the initial generation of related radical cations followed by either hydration or deprotonation reactions in agreement with mechanistic pathways inferred from detailed mechanistic studies. The guanine radical cation has been shown to be implicated in three other nucleophilic additions that give rise to DNA-protein and DNA-DNA cross-links in model systems. Evidence was recently provided for the occurrence of these three reactions in cellular DNA. There is growing evidence that one-electron oxidation reactions of nucleobases whose mechanisms have been characterized in model studies involving aqueous solutions take place in a similar way in cells. It may also be pointed out that the above cross-linked lesions are only produced from the guanine radical cation and may be considered as diagnostic products of the direct effect of ionizing radiation.

Governance-Default Risk Relationship and the Demand for Intermediated and Non-Intermediated Debt

Directory of Open Access Journals (Sweden)

Husam Aldamen

2012-09-01

Full Text Available This paper explores the impact of corporate governance on the demand for intermediated debt (asset finance, bank debt, non-bank private debt and non-intermediated debt (public debt in the Australian debt market. Relative to other countries the Australian debt market is characterised by higher proportions of intermediated or private debt with a lower inherent level of information asymmetry in that private lenders have greater access to financial information (Gray, Koh & Tong 2009. Our firm level, cross-sectional evidence suggests that higher corporate governance impacts demand for debt via the mitigation of default risk. However, this relationship is not uniform across all debt types. Intermediated debt such as bank and asset finance debt are more responsive to changes in governance-default risk relationship than non-bank and non-intermediated debt. The implication is that a firm’s demand for different debt types will reflect its governance-default risk profile.

Processing and validation of intermediate energy evaluated data files

International Nuclear Information System (INIS)

2000-01-01

Current accelerator-driven and other intermediate energy technologies require accurate nuclear data to model the performance of the target/blanket assembly, neutron production, activation, heating and damage. In a previous WPEC subgroup, SG13 on intermediate energy nuclear data, various aspects of intermediate energy data, such as nuclear data needs, experiments, model calculations and file formatting issues were investigated and categorized to come to a joint evaluation effort. The successor of SG13, SG14 on the processing and validation of intermediate energy evaluated data files, goes one step further. The nuclear data files that have been created with the aforementioned information need to be processed and validated in order to be applicable in realistic intermediate energy simulations. We emphasize that the work of SG14 excludes the 0-20 MeV data part of the neutron evaluations, which is supposed to be covered elsewhere. This final report contains the following sections: section 2: a survey of the data files above 20 MeV that have been considered for validation in SG14; section 3: a summary of the review of the 150 MeV intermediate energy data files for ENDF/B-VI and, more briefly, the other libraries; section 4: validation of the data library against an integral experiment with MCNPX; section 5: conclusions. (author)

Magnetic impurity coupled to interacting conduction electrons

International Nuclear Information System (INIS)

Schork, T.

1996-01-01

We consider a magnetic impurity which interacts by hybridization with a system of weakly correlated electrons and determine the energy of the ground state by means of a 1/N f expansion. The correlations among the conduction electrons are described by a Hubbard Hamiltonian and are treated to the lowest order in the interaction strength. We find that their effect on the Kondo temperature, T K , in the Kondo limit is twofold: first, the position of the impurity level is shifted due to the reduction of charge fluctuations, which reduces T K . Secondly, the bare Kondo exchange coupling is enhanced as spin fluctuations are enlarged. In total, T K increases. Both corrections require intermediate states beyond the standard Varma-Yafet ansatz. This shows that the Hubbard interaction does not just provide quasiparticles, which hybridize with the impurity, but also renormalizes the Kondo coupling. copyright 1996 The American Physical Society

Silver nanoparticle catalysed redox reaction: An electron relay effect

International Nuclear Information System (INIS)

Mallick, Kaushik; Witcomb, Mike; Scurrell, Mike

2006-01-01

A silver cluster shows efficient catalytic activity in a redox reaction because the cluster acts as the electron relay centre behaving alternatively as an acceptor and as a donor of electrons. An effective transfer of electrons is possible when the redox potential of the cluster is intermediate between the electron donor and electron acceptor system

Magnetic-Field Control Of Tunnel-Coupling In Strongly Confined One-Dimensional Electron Systems

Science.gov (United States)

Fischer, S. F.; Apetrii, G.; Kunze, U.; Schuh, D.; Abstreiter, G.

2007-04-01

One-dimensional (1D) ballistic electron transport is studied through stacked 1D quantum conductors separated by a thin tunneling barrier. The 1D electron systems of large 1D subband spacings (more than 10 meV) allow single mode operation. Degeneracies of 1D subbands of equal lateral mode index are lifted by the formation of symmetric and antisymmetric states and are depicted by anti-crossings of transconductance maxima. We observe a mode-dependent turnover from level anti-crossings to crossings in longitudinal magnetic fields.

Constraints on mechanisms and rates of anaerobic oxidation of methane by microbial consortia: process-based modeling of ANME-2 archaea and sulfate reducing bacteria interactions

Directory of Open Access Journals (Sweden)

B. Orcutt

2008-11-01

Full Text Available Anaerobic oxidation of methane (AOM is the main process responsible for the removal of methane generated in Earth's marine subsurface environments. However, the biochemical mechanism of AOM remains elusive. By explicitly resolving the observed spatial arrangement of methanotrophic archaea and sulfate reducing bacteria found in consortia mediating AOM, potential intermediates involved in the electron transfer between the methane oxidizing and sulfate reducing partners were investigated via a consortium-scale reaction transport model that integrates the effect of diffusional transport with thermodynamic and kinetic controls on microbial activity. Model simulations were used to assess the impact of poorly constrained microbial characteristics such as minimum energy requirements to sustain metabolism and cell specific rates. The role of environmental conditions such as the influence of methane levels on the feasibility of H₂, formate and acetate as intermediate species, and the impact of the abundance of intermediate species on pathway reversal were examined. The results show that higher production rates of intermediates via AOM lead to increased diffusive fluxes from the methane oxidizing archaea to sulfate reducing bacteria, but the build-up of the exchangeable species can cause the energy yield of AOM to drop below that required for ATP production. Comparison to data from laboratory experiments shows that under the experimental conditions of Nauhaus et al. (2007, none of the potential intermediates considered here is able to support metabolic activity matching the measured rates.

Bridge: Intelligent Tutoring with Intermediate Representations

Science.gov (United States)

1988-05-01

Research and Development Center and Psychology Department University of Pittsburgh Pittsburgh, PA. 15260 The Artificial Intelligence and Psychology...problem never introduces more than one unfamiliar plan. Inteligent Tutoring With Intermediate Representations - Bonar and Cunniigbam 4 You must have a... Inteligent Tutoring With ntermediate Representations - Bonar and Cunningham 7 The requirements are specified at four differcnt levels, corresponding to

One-Dimensional Electron Transport Layers for Perovskite Solar Cells

Directory of Open Access Journals (Sweden)

Ujwal K. Thakur

2017-04-01

Full Text Available The electron diffusion length (Ln is smaller than the hole diffusion length (Lp in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D structures such as nanowires (NWs and nanotubes (NTs as electron transport layers (ETLs is a promising method of achieving high performance halide perovskite solar cells (HPSCs. ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs. This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells.

One-Dimensional Electron Transport Layers for Perovskite Solar Cells

Science.gov (United States)

Thakur, Ujwal K.; Kisslinger, Ryan; Shankar, Karthik

2017-01-01

The electron diffusion length (Ln) is smaller than the hole diffusion length (Lp) in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D) structures such as nanowires (NWs) and nanotubes (NTs) as electron transport layers (ETLs) is a promising method of achieving high performance halide perovskite solar cells (HPSCs). ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs) as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs). This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells. PMID:28468280

Negotiating comfort in low energy housing: The politics of intermediation

International Nuclear Information System (INIS)

Grandclément, Catherine; Karvonen, Andrew; Guy, Simon

2015-01-01

Optimising the energy performance of buildings is technically and economically challenging but it also has significant social implications. Maintaining comfortable indoor conditions while reducing energy consumption involves careful design, construction, and management of the built environment and its inhabitants. In this paper, we present findings from the study of a new low energy building for older people in Grenoble, France where conflicts emerged over the simultaneous pursuit of energy efficiency and comfort. The findings contribute to the contemporary literature on the sociotechnical study of buildings and energy use by focusing on intermediation, those activities that associate a technology to end users. Intermediation activities take many forms, and in some cases, can result in the harmonisation or alignment of energy efficiency goals and comfort goals. In other cases, intermediation is unsuccessful, leading to the conventional dichotomy between optimising technical performance and meeting occupant preferences. By highlighting the multiple ways that comfort and energy efficiency is negotiated, we conclude that buildings are provisional achievements that are constantly being intermediated. This suggests that building energy efficiency policies and programmes need to provide opportunities for intermediaries to negotiate the desires and preferences of the multiple stakeholders that are implicated in low energy buildings. -- Highlights: •Energy efficiency and comfort are two possibly contradictory aims of buildings. •We study the pursuit of these aims at the occupation stage of a new building. •Aligning these aims involve negotiating them with occupants. •Intermediation processes are key to such negotiations. •Intermediation processes involve both actors and technical devices

Mechanisms of dust grain charging in plasma with allowance for electron emission processes

Energy Technology Data Exchange (ETDEWEB)

Mol’kov, S. I.; Savin, V. N., E-mail: moped@onego.ru [Petrozavodsk State University (Russian Federation)

2017-02-15

The process of dust grain charging is described with allowance for secondary, ion-induced, photoelectric, and thermal electron emission from the grain surface. The roughness of the grain surface is taken into account. An intermediate charging regime involving ion–atom collisions and electron ionization in the perturbed plasma region is analyzed using the moment equations and Poisson’s equation. A calculation method is proposed that allows one to take into account the influence of all the above effects and determine the radius of the plasma region perturbed by the dust grain.

Correlated Default and Financial Intermediation

OpenAIRE

Gregory Phelan

2015-01-01

Financial intermediation naturally arises when knowledge about the aggregate state is valuable for managing investments and lenders cannot easily observe the aggregate state. I show this using a costly enforcement model in which lenders need ex-post incentives to enforce payments from defaulted loans and borrowers' payoffs are correlated. When projects have correlated outcomes, learning the state of one project (via enforcement) provides information about the states of other projects. A large...

Formation of quinones by one-electron oxidation in the metabolism of benzo[a]pyrene and 6-fluorobenzo[a]pyrene

International Nuclear Information System (INIS)

Cavalieri, E.; Wong, A.; Cremonesi, P.; Warner, C.; Rogan, E.

1986-01-01

Metabolic activation of polycyclic aromatic hydrocarbons (PAH), as well as other chemical carcinogens, occurs by two major pathways: One-electron oxidation and two-electron oxidation, or monooxygenation. One-electron oxidation generates radical cations or radicals, depending on the molecule in which the oxidation occurs, whereas two-electron oxidation produces oxygenated metabolites. Radical cations of PAH are ultimate electrophilic metabolites capable of binding to cellular macromolecules to initiate the tumor process. In this paper the authors will provide evidence that one-electron oxidation is involved not only in PAH carcinogenesis, but also in the formation of certain metabolites. Metabolism of benzo[a]pyrene (BP) by cytochrome P-450 monooxygenase yields three classes of products: phenols, dihydrodiols and the quinones, 1,6-, 3,6- and 6,12- dione

Calculation of electron-beam induced displacement in thin films by using parameter-reduced formulas

Energy Technology Data Exchange (ETDEWEB)

Yan, Qiang [College of Nuclear Science and Technology, Harbin Engineering University, Harbin 150001 (China); Chen, Di [Department of Nuclear Engineering, Texas A& M University, College Station, TX 77843 (United States); Wang, Qingyu; Li, Zhongyu [College of Nuclear Science and Technology, Harbin Engineering University, Harbin 150001 (China); Shao, Lin, E-mail: lshao@tamu.edu [Department of Nuclear Engineering, Texas A& M University, College Station, TX 77843 (United States)

2017-03-01

Based on the Mott cross sections of relativistic electron collisions with atoms, we calculate displacement creation by electron beams of arbitrary energies (up to 100 MeV) in thin films of arbitrary atomic numbers (up to Z = 90). In a comparison with Mont Carlo full damage cascade simulations, we find that total number of displacements in a film can be accurately estimated as the product of average displacements created per collision and average collision numbers in the film. To calculate average displacements per electron-atom collision, energy transfer from Mott cross section is combined with NRT model. To calculate collision numbers, mean deflection angles and multi-scattering theory are combined to extract collision number dependence on film thickness. For each key parameter, parameter-reduced formulas are obtained from data fitting. The fitting formulas provide a quick and accurate method to estimate radiation damage caused by electron beams.

Multifragmentation in intermediate energy heavy ion collisions

International Nuclear Information System (INIS)

Jacak, B.V.; Britt, H.C.; Claesson, G.

1986-01-01

There has been considerable recent interest in the production of intermediate mass fragments (A > 4) in intermediate and high energy nucleus-nucleus collisions. The mechanism for production of these fragments is not well understood and has been described by models employing a variety of assumptions. Some examples are: disassembly of a system in thermal equilibrium into nucleons and nuclear fragments, liquid-vapor phase transitions in nuclear matter, final state coalescence of nucleons and dynamical correlations between nucleons at breakup. Previous studies of fragment production, with one exception, have been single particle inclusive measurements; the observed fragment mass (or charge) distributions can be described by all of the models above. To gain insight into the fragment production mechanism, the authors used the GSI/LBL Plastic Ball detector system to get full azimuthal coverage for intermediate mass fragments in the forward hemisphere in the center of mass system while measuring all the light particles in each event. The authors studied the systems 200 MeV/nucleon Au + Au and Au + Fe

Improvement of the crystallographic orientation of double-layered perpendicular recording media by using CoCr (Mo)/Cu intermediate layers

International Nuclear Information System (INIS)

Tamai, Ichiro; Yamamoto, T.; Kikukawa, A.; Tanahashi, K.; Ishikawa, A.; Futamoto, M.

2001-01-01

We have introduced intermediate layers of CoCr/Cu and CoCrMo/Cu between a CoCrPtB recording layer and a soft-magnetic CoTaZr underlayer. The combination of the FCC-Cu first-intermediate layer and the HCP-CoCrMo second-intermediate layer was found to enhance the c-axis vertical orientation of the CoCrPtB recording layer. In media with intermediate layers of CoCrMo/Cu, the thickness of the intermediate layers can be reduced without sacrificing good magnetic properties, and this leads to high resolutions

MHD intermediate shock discontinuities: Pt. 1

International Nuclear Information System (INIS)

Kennel, C.F.; Blandford, R.D.; Coppi, P.

1989-01-01

Recent numerical investigations have focused attention once more on the role of intermediate shocks in MHD. Four types of intermediate shock are identified using a graphical representation of the MHD Rankine-Hugoniot conditions. This same representation can be used to exhibit the close relationship of intermediate shocks to switch-on shocks and rotational discontinuities. The conditions under which intermediate discontinuities can be found are elucidated. The variations in velocity, pressure, entropy and magnetic-field jumps with upstream parameters in intermediate shocks are exhibited graphically. The evolutionary arguments traditionally advanced against intermediate shocks may fail because the equations of classical MHD are not strictly hyperbolic. (author)

Heme-bound nitroxyl, hydroxylamine, and ammonia ligands as intermediates in the reaction cycle of cytochrome c nitrite reductase: a theoretical study.

Science.gov (United States)

Bykov, Dmytro; Plog, Matthias; Neese, Frank

2014-01-01

In this article, we consider, in detail, the second half-cycle of the six-electron nitrite reduction mechanism catalyzed by cytochrome c nitrite reductase. In total, three electrons and four protons must be provided to reach the final product, ammonia, starting from the HNO intermediate. According to our results, the first event in this half-cycle is the reduction of the HNO intermediate, which is accomplished by two PCET reactions. Two isomeric radical intermediates, HNOH(•) and H2NO(•), are formed. Both intermediates are readily transformed into hydroxylamine, most likely through intramolecular proton transfer from either Arg114 or His277. An extra proton must enter the active site of the enzyme to initiate heterolytic cleavage of the N-O bond. As a result of N-O bond cleavage, the H2N(+) intermediate is formed. The latter readily picks up an electron, forming H2N(+•), which in turn reacts with Tyr218. Interestingly, evidence for Tyr218 activity was provided by the mutational studies of Lukat (Biochemistry 47:2080, 2008), but this has never been observed in the initial stages of the overall reduction process. According to our results, an intramolecular reaction with Tyr218 in the final step of the nitrite reduction process leads directly to the final product, ammonia. Dissociation of the final product proceeds concomitantly with a change in spin state, which was also observed in the resonance Raman investigations of Martins et al. (J Phys Chem B 114:5563, 2010).

Microwave assisted sintering of gadolinium doped barium cerate electrolyte for intermediate temperature solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Kumar, Arumugam Senthil, E-mail: senthu.ramp@gmail.com [Department of Physics, PSG College of Technology, Coimbatore, 641 004, Tamilnadu (India); Balaji, Ramamoorthy [Department of Physics, PSG College of Technology, Coimbatore, 641 004, Tamilnadu (India); Jayakumar, Srinivasalu [Department of Physics, PSG Institute of Technology and Applied Research, Coimbatore, 641 062, Tamilnadu (India); Pradeep, Chandran [Department of Physics, Indian Institute of Technology, Madras, 600 036, Tamilnadu (India)

2016-10-01

In Solid Oxide Fuel Cell (SOFC), electrolyte plays a vital role to increase the energy conversion efficiency. The main hurdle of such electrolyte in fuel cell is its higher operating temperature (1000 °C) which results in design limitation and higher fabrication cost. In order to reduce the operating temperature of SOFC, a suitable electrolyte has been prepared through co-precipitation method followed by microwave sintering of solid ceramic. The calcination temperature for the as-prepared powder was identified using Differential Scanning Calorimetry. The crystal structure of the sample was found to exhibit its orthorhombic perovskite structure. The particle size was determined using High-Resolution Transmission Electron Microscope with uniform in shape and size, match with XRD results and confirmed from structural analysis. Thus, the sample prepared via co-precipitation method and the solid ceramic sintered through microwave can be a promising electrolyte for fuel cells operated at intermediate temperature. - Highlights: • To synthesis the composite electrolyte by chemical method and sinter using microwave. • To reduce the operating temperature of electrolyte for high ionic conductivity in SOFC's. • To study the phase purity and to develop nanocomposite at reduced temperature.

Survival outcome of intermediate risk neuroblastoma at Children Cancer Hospital Egypt

Directory of Open Access Journals (Sweden)

Hossam Elzomor

2018-03-01

Conclusion: A very high rate of survival is currently achievable in patients with intermediate risk neuroblastoma by chemotherapy or chemotherapy and surgery. In addition to response, our plan is to adopt biologically-based treatment to reduce treatment-induced complications among survivors.

One electron reduction of triphenyl methane dyes by hydrated electrons

Energy Technology Data Exchange (ETDEWEB)

Bhasikuttan, A C; Shastri, L V; Sapre, A V; Rama Rao, K V.S. [Bhabha Atomic Research Centre, Bombay (India). Chemistry Div.

1994-12-31

Electron reaction rates for the triphenylmethane (TPM) dyes have been evaluated. Spectral characteristics of the resulting dye radicals have been determined. Evolution of the transient spectra shows intramolecular rearrangement in the radical from brilliant green and malachite green. (author). 3 refs., 1 fig., 1 tab.

One electron reduction of triphenyl methane dyes by hydrated electrons

International Nuclear Information System (INIS)

Bhasikuttan, A.C.; Shastri, L.V.; Sapre, A.V.; Rama Rao, K.V.S.

1994-01-01

Electron reaction rates for the triphenylmethane (TPM) dyes have been evaluated. Spectral characteristics of the resulting dye radicals have been determined. Evolution of the transient spectra shows intramolecular rearrangement in the radical from brilliant green and malachite green. (author). 3 refs., 1 fig., 1 tab

Tensor polarized deuteron targets for intermediate energy physics experiments

International Nuclear Information System (INIS)

Meyer, W.; Schilling, E.

1985-03-01

At intermediate energies measurements from a tensor polarized deuteron target are being prepared for the following reactions: the photodisintegration of the deuteron, the elastic pion-deuteron scattering and the elastic electron-deuteron scattering. The experimental situation of the polarization experiments for these reactions is briefly discussed in section 2. In section 3 the definitions of the deuteron polarization and the possibilities to determine the vector and tensor polarization are given. Present tensor polarization values and further improvements in this field are reported in section 4. (orig.)

Nuclear-electronic orbital reduced explicitly correlated Hartree-Fock approach: Restricted basis sets and open-shell systems

International Nuclear Information System (INIS)

Brorsen, Kurt R.; Sirjoosingh, Andrew; Pak, Michael V.; Hammes-Schiffer, Sharon

2015-01-01

The nuclear electronic orbital (NEO) reduced explicitly correlated Hartree-Fock (RXCHF) approach couples select electronic orbitals to the nuclear orbital via Gaussian-type geminal functions. This approach is extended to enable the use of a restricted basis set for the explicitly correlated electronic orbitals and an open-shell treatment for the other electronic orbitals. The working equations are derived and the implementation is discussed for both extensions. The RXCHF method with a restricted basis set is applied to HCN and FHF − and is shown to agree quantitatively with results from RXCHF calculations with a full basis set. The number of many-particle integrals that must be calculated for these two molecules is reduced by over an order of magnitude with essentially no loss in accuracy, and the reduction factor will increase substantially for larger systems. Typically, the computational cost of RXCHF calculations with restricted basis sets will scale in terms of the number of basis functions centered on the quantum nucleus and the covalently bonded neighbor(s). In addition, the RXCHF method with an odd number of electrons that are not explicitly correlated to the nuclear orbital is implemented using a restricted open-shell formalism for these electrons. This method is applied to HCN + , and the nuclear densities are in qualitative agreement with grid-based calculations. Future work will focus on the significance of nonadiabatic effects in molecular systems and the further enhancement of the NEO-RXCHF approach to accurately describe such effects

Nuclear-electronic orbital reduced explicitly correlated Hartree-Fock approach: Restricted basis sets and open-shell systems

Energy Technology Data Exchange (ETDEWEB)

Brorsen, Kurt R.; Sirjoosingh, Andrew; Pak, Michael V.; Hammes-Schiffer, Sharon, E-mail: shs3@illinois.edu [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Ave., Urbana, Illinois 61801 (United States)

2015-06-07

The nuclear electronic orbital (NEO) reduced explicitly correlated Hartree-Fock (RXCHF) approach couples select electronic orbitals to the nuclear orbital via Gaussian-type geminal functions. This approach is extended to enable the use of a restricted basis set for the explicitly correlated electronic orbitals and an open-shell treatment for the other electronic orbitals. The working equations are derived and the implementation is discussed for both extensions. The RXCHF method with a restricted basis set is applied to HCN and FHF{sup −} and is shown to agree quantitatively with results from RXCHF calculations with a full basis set. The number of many-particle integrals that must be calculated for these two molecules is reduced by over an order of magnitude with essentially no loss in accuracy, and the reduction factor will increase substantially for larger systems. Typically, the computational cost of RXCHF calculations with restricted basis sets will scale in terms of the number of basis functions centered on the quantum nucleus and the covalently bonded neighbor(s). In addition, the RXCHF method with an odd number of electrons that are not explicitly correlated to the nuclear orbital is implemented using a restricted open-shell formalism for these electrons. This method is applied to HCN{sup +}, and the nuclear densities are in qualitative agreement with grid-based calculations. Future work will focus on the significance of nonadiabatic effects in molecular systems and the further enhancement of the NEO-RXCHF approach to accurately describe such effects.

Angular correlation of autoionization electrons and photons emitted from collisionally aligned atomic states

International Nuclear Information System (INIS)

Eichler, J.; Fritsch, W.

1976-01-01

The angular correlation of autoionization electrons or of photons ejected from collisionally aligned excited atoms is calculated assuming unpolarized beam and target, and polarization-insensitive detectors. Starting from the two-step hypothesis for the formation and decay of the intermediate excited atoms, the angular correlation is expressed in terms of the density matrix describing the excited system. Using the symmetries of the density matrix, a minimal set of independent matrix elements is given and the conditions for which a complete determination of this set is experimentally possible are discussed. For the case of electron emission, simple examples are pointed out in which the angular correlation is independent of the reduced Coulomb matrix elements describing the decay. (author)

Technological guns which form the profiled electron beans

International Nuclear Information System (INIS)

Mel'nik, V.I.

1998-01-01

Electron guns with high-voltage glow discharge are developed which form disc - and tubule-like,hollow conic and linear electron beams,as well as devices and systems for control of gun parameter and technological processes in low and intermediate vacuum

Early Events, Kinetic Intermediates and the Mechanism of Protein Folding in Cytochrome c

Directory of Open Access Journals (Sweden)

David S. Kliger

2009-04-01

Full Text Available Kinetic studies of the early events in cytochrome c folding are reviewed with a focus on the evidence for folding intermediates on the submillisecond timescale. Evidence from time-resolved absorption, circular dichroism, magnetic circular dichroism, fluorescence energy and electron transfer, small-angle X-ray scattering and amide hydrogen exchange studies on the t £ 1 ms timescale reveals a picture of cytochrome c folding that starts with the ~ 1-ms conformational diffusion dynamics of the unfolded chains. A fractional population of the unfolded chains collapses on the 1 – 100 ms timescale to a compact intermediate IC containing some native-like secondary structure. Although the existence and nature of IC as a discrete folding intermediate remains controversial, there is extensive high time-resolution kinetic evidence for the rapid formation of IC as a true intermediate, i.e., a metastable state separated from the unfolded state by a discrete free energy barrier. Final folding to the native state takes place on millisecond and longer timescales, depending on the presence of kinetic traps such as heme misligation and proline mis-isomerization. The high folding rates observed in equilibrium molten globule models suggest that IC may be a productive folding intermediate. Whether it is an obligatory step on the pathway to the high free energy barrier associated with millisecond timescale folding to the native state, however, remains to be determined.

One-electron transfer equilibria and redox potentials of radicals studied by pulse radiolysis

International Nuclear Information System (INIS)

Meisel, D.; Czapski, G.

1975-01-01

The pulse radiolysis technique is utilized for measurements of the equilibrium constants for electron transfer between the durosemiquinone radical anion and oxygen, menadione, and indigodisulfonate. These equilibrium constants are in turn used for calculations of one-electron redox potentials for these systems. Each of these equilibrium constants was determined experimentally and independently and found to be self-consistent. Only for the reactions of the semiquinone radical ions with oxygen could the electron transfer reaction be followed directly. For the reactions between the various quinone-semiquinone systems substantial indirect evidence is presented that these equilibria are achieved rapidly. In those cases equilibrium constants were determined from studies of the effect of quinone concentrations on the relative yields of the semiquinones. A method for distinguishing between kinetic competition and equilibrium is outlined and its usefulness is emphasized. The DQ parallel DQ - (DQ = duroquinone) and IDS parallel IDS - (IDS = indigodisulfonate) systems were employed as reference couples as the redox potentials for those systems are either available in the literature (IDS parallel IDS - ) or may be calculated from available data (DQ parallel DQ - ). Taking E 7 1 , the redox potential for the first one-electron reduction step at pH 7, of DQ parallel DQ - as -0.235 V or of IDS parallelIDS - as -0.247 V both yield E 7 1 = -0.325 V for the O 2 parallel O 2 - system (1 atm of O 2 ) and E 2 1 = -0.20 V for the menadione system. (U.S.)

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.

One-step approach to prepare magnetic iron oxide/reduced graphene oxide nanohybrid for efficient organic and inorganic pollutants removal

International Nuclear Information System (INIS)

Thakur, Suman; Karak, Niranjan

2014-01-01

An environmentally friendly effective technique was demonstrated to prepare iron oxide/reduced graphene oxide nanohybrid (IO/RGO) at room temperature by using banana peel ash aqueous extract as the base source and Colocasia esculenta leaves aqueous extract as the reducing agent. The nanohybrid was characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, transmission electron microscopy, vibrating sample magnetometry, Raman spectroscopy and thermal studies. The results indicated the decoration of superparamagnetic IO nanoparticles on the surface of the RGO. Both organic and inorganic pollutants were effectively removed from the contaminated water (for Pb 2+ and Cd 2+ within 10 min, whereas for tetrabromobisphenol A within 30 min) by IO/RGO. The study revealed that adsorption followed pseudo-second order kinetics and isotherms were well described by the Langmuir model in all the cases. The thermodynamics parameters (ΔG°, ΔS° and ΔH°) were calculated from the temperature dependent isotherms and indicated that the adsorptions were endothermic and spontaneous. - Highlights: • Eco-friendly one step preparation of iron oxide/reduced graphene oxide nanohybrid. • The nanohybrid has excellent pollutants removal capacity from contaminated water. • Superparamagnetic iron oxide nanoparticles help in easy recycle. • The adsorption processes of pollutants are endothermic and spontaneous

One-step approach to prepare magnetic iron oxide/reduced graphene oxide nanohybrid for efficient organic and inorganic pollutants removal

Energy Technology Data Exchange (ETDEWEB)

Thakur, Suman; Karak, Niranjan, E-mail: karakniranjan@yahoo.com

2014-04-01

An environmentally friendly effective technique was demonstrated to prepare iron oxide/reduced graphene oxide nanohybrid (IO/RGO) at room temperature by using banana peel ash aqueous extract as the base source and Colocasia esculenta leaves aqueous extract as the reducing agent. The nanohybrid was characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, transmission electron microscopy, vibrating sample magnetometry, Raman spectroscopy and thermal studies. The results indicated the decoration of superparamagnetic IO nanoparticles on the surface of the RGO. Both organic and inorganic pollutants were effectively removed from the contaminated water (for Pb{sup 2+} and Cd{sup 2+} within 10 min, whereas for tetrabromobisphenol A within 30 min) by IO/RGO. The study revealed that adsorption followed pseudo-second order kinetics and isotherms were well described by the Langmuir model in all the cases. The thermodynamics parameters (ΔG°, ΔS° and ΔH°) were calculated from the temperature dependent isotherms and indicated that the adsorptions were endothermic and spontaneous. - Highlights: • Eco-friendly one step preparation of iron oxide/reduced graphene oxide nanohybrid. • The nanohybrid has excellent pollutants removal capacity from contaminated water. • Superparamagnetic iron oxide nanoparticles help in easy recycle. • The adsorption processes of pollutants are endothermic and spontaneous.

Pulse radiolysis study of the intermediates formed in ionic liquids. Intermediate spectra in the p-terphenyl solution in the ionic liquid methyltributylammonium bis[(trifluoromethyl)sulfonyl]imide

International Nuclear Information System (INIS)

Grodkowski, J.; Kocia, R.; Mirkowski, J.

2006-01-01

Room temperature ionic liquids (Il) are non-volatile,and non-flammable and serve as good solvents for various reactions, mainly for g reen processing . To understand the effect of these solvents on the chemical reactions, the rate constants of several elementary reactions in ionic liquids have been studied by the pulse radiolysis technique. In this study, the formation of intermediates derived from p-terphenyl (Tp) in the ionic liquid methyl tributylammonium bis[(trifluoromethyl)sulfonyl] imide (R 4 NNTf 2 ) solutions have been studied by pulse radiolysis as a part of broader studies concerning CO 2 reduction. The registered spectra can be explained by CO 2 reaction with solvated and dry electrons thus eliminating one path of TP ·- formation. Some TP ·- are formed by reaction of excited TP *- states with Tea. Direct reactions involving Tp, TP ·- , CO 2 and CO 2 ·- are too slow to be observed in pulse radiolysis time scale

The Implications of Intermediate Stop Operations on Aviation Emissions and Climate

Directory of Open Access Journals (Sweden)

Florian Linke

2017-12-01

Full Text Available Among the various transport modes aviation's impact on climate change deserves special attention. Due to typical flight altitudes in the upper troposphere and above, the effect of aircraft engine emissions like e.g. water vapour, nitrogen oxides and aerosols on radiative forcing agents is substantial. The projected doubling of aircraft movements in the next 15 years will lead to an increase of aviation's impact on climate and requires immediate mitigation options. Besides technological measures also new operational strategies are widely discussed; one of these concepts which has been subject of several studies in the past is Intermediate Stop Operations (ISO. It is based on the idea to reduce the stage length of flights by performing one or more intermediate landings during a mission. Here, we analyse the ISO concept by combining different models, which include a realistic traffic simulation taking into account operational constraints and ambient conditions, like e.g. wind, the calculation of engine emissions and the integration of a climate response model. We analyse the ISO concept for today's worldwide aircraft fleet, including its influence on global emissions distributions as well as the impact on climate change by taking into account CO2 and non-CO2 effects, arising from contrail-cirrus, water vapour and nitrogen oxide emissions. We show in agreement with earlier findings that due to shorter flight distances the amount of fuel burnt over the mission can be reduced by roughly 5 % on average globally. For the first time, we quantify the climate impact of ISO, where the flight trajectory is optimised for fuel use and the aircraft is not redesigned for the ISO procedure. We find an increased warming effect, which arises from nitrogen oxide and water vapour emissions, which are released at higher cruise altitudes and which over-compensate reduced warming effects from CO2 and contrail-cirrus. However, we expect a climate impact reduction for

Reactor-moderated intermediate-energy neutron beams for neutron-capture therapy

International Nuclear Information System (INIS)

Less, T.J.

1987-01-01

One approach to producing an intermediate energy beam is moderating fission neutrons escaping from a reactor core. The objective of this research is to evaluate materials that might produce an intermediate beam for NCT via moderation of fission neutrons. A second objective is to use the more promising moderator material in a preliminary design of an NCT facility at a research reactor. The evaluations showed that several materials or combinations of materials could produce a moderator source for an intermediate beam for NCT. The best neutron spectrum for use in NCT is produced by Al 2 O 3 , but mixtures of Al metal and D 2 O are also attractive. Using the best moderator materials, results were applied to the design of an NCT moderator at the Georgia Institute of Technology Research Reactor's bio-medical facility. The amount of photon shielding and thermal neutron absorber were optimized with respect to the desired photon dose rate and intermediate neutron flux at the patient position

Top predators induce the evolutionary diversification of intermediate predator species.

Science.gov (United States)

Zu, Jian; Yuan, Bo; Du, Jianqiang

2015-12-21

We analyze the evolutionary branching phenomenon of intermediate predator species in a tritrophic food chain model by using adaptive dynamics theory. Specifically, we consider the adaptive diversification of an intermediate predator species that feeds on a prey species and is fed upon by a top predator species. We assume that the intermediate predator׳s ability to forage on the prey can adaptively improve, but this comes at the cost of decreased defense ability against the top predator. First, we identify the general properties of trade-off relationships that lead to a continuously stable strategy or to evolutionary branching in the intermediate predator species. We find that if there is an accelerating cost near the singular strategy, then that strategy is continuously stable. In contrast, if there is a mildly decelerating cost near the singular strategy, then that strategy may be an evolutionary branching point. Second, we find that after branching has occurred, depending on the specific shape and strength of the trade-off relationship, the intermediate predator species may reach an evolutionarily stable dimorphism or one of the two resultant predator lineages goes extinct. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Novel semiconductor solar cell structures: The quantum dot intermediate band solar cell

International Nuclear Information System (INIS)

Marti, A.; Lopez, N.; Antolin, E.; Canovas, E.; Stanley, C.; Farmer, C.; Cuadra, L.; Luque, A.

2006-01-01

The Quantum Dot Intermediate Band Solar Cell (QD-IBSC) has been proposed for studying experimentally the operating principles of a generic class of photovoltaic devices, the intermediate band solar cells (IBSC). The performance of an IBSC is based on the properties of a semiconductor-like material which is characterised by the existence of an intermediate band (IB) located within what would otherwise be its conventional bandgap. The improvement in efficiency of the cell arises from its potential (i) to absorb below bandgap energy photons and thus produce additional photocurrent, and (ii) to inject this enhanced photocurrent without degrading its output photo-voltage. The implementation of the IBSC using quantum dots (QDs) takes advantage of the discrete nature of the carrier density of states in a 0-dimensional nano-structure, an essential property for realising the IB concept. In the QD-IBSC, the IB arises from the confined electron states in an array of quantum dots. This paper reviews the operation of the first prototype QD-IBSCs and discusses some of the lessons learnt from their characterisation

Novel semiconductor solar cell structures: The quantum dot intermediate band solar cell

Energy Technology Data Exchange (ETDEWEB)

Marti, A. [Instituto de Energia Solar-UPM, ETSIT de Madrid, Ciudad Universitaria sn, 28040 Madrid (Spain)]. E-mail: amarti@etsit.upm.es; Lopez, N. [Instituto de Energia Solar-UPM, ETSIT de Madrid, Ciudad Universitaria sn, 28040 Madrid (Spain); Antolin, E. [Instituto de Energia Solar-UPM, ETSIT de Madrid, Ciudad Universitaria sn, 28040 Madrid (Spain); Canovas, E. [Instituto de Energia Solar-UPM, ETSIT de Madrid, Ciudad Universitaria sn, 28040 Madrid (Spain); Stanley, C. [Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Farmer, C. [Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Cuadra, L. [Departamento de Teoria de la Senal y Comunicaciones- Escuela Politecnica Superior, Universidad de Alcala, Ctra. Madrid-Barcelona, km. 33600, 28805-Alcala de Henares (Madrid) (Spain); Luque, A. [Instituto de Energia Solar-UPM, ETSIT de Madrid, Ciudad Universitaria sn, 28040 Madrid (Spain)

2006-07-26

The Quantum Dot Intermediate Band Solar Cell (QD-IBSC) has been proposed for studying experimentally the operating principles of a generic class of photovoltaic devices, the intermediate band solar cells (IBSC). The performance of an IBSC is based on the properties of a semiconductor-like material which is characterised by the existence of an intermediate band (IB) located within what would otherwise be its conventional bandgap. The improvement in efficiency of the cell arises from its potential (i) to absorb below bandgap energy photons and thus produce additional photocurrent, and (ii) to inject this enhanced photocurrent without degrading its output photo-voltage. The implementation of the IBSC using quantum dots (QDs) takes advantage of the discrete nature of the carrier density of states in a 0-dimensional nano-structure, an essential property for realising the IB concept. In the QD-IBSC, the IB arises from the confined electron states in an array of quantum dots. This paper reviews the operation of the first prototype QD-IBSCs and discusses some of the lessons learnt from their characterisation.

[Electron transfer, ionization, and excitation in atomic collisions]. Final technical report, June 15, 1986 - June 14, 1998

International Nuclear Information System (INIS)

1998-01-01

The research on theoretical atomic collisions that was funded at The Pennsylvania State University's Wilkes-Barre Campus by DOE from 1986 to 1998 was carried out by Winger from 1986 to 1989 and by Winter and Alston from 1989 to 1998. The fundamental processes of electron transfer, ionization, and excitation in ion-ion, ion-atom, and, more recently, ion-molecule collisions were addressed. These collision processes were treated in the context of simple one-electron, quasi-one-electron, or two-electron systems in order to provide unambiguous results and reveal more clearly the collisional mechanisms. Winter's work generally focused on the intermediate projectile-energy range corresponding to proton energies from about ten to a few hundred keV. In this velocity-matching energy range, the electron-transfer cross section reaches a peak, and many states, including electron-transfer and ionization states, contribute to the overall electron-cloud distribution and transition probabilities; a large number of states are coupled, and therefore perturbative approaches are generally inappropriate. These coupled-state calculations were sometimes also extended to higher energies to join with perturbative results. Alston concentrated on intermediate-energy asymmetric collision systems, for which coupling with the projectile is weaker, but many target states are included, and on high energies (MeV energies). Thus, while perturbation theory for electron transfer is valid, it is not adequate to first order. The studies by Winter and Alston described were often done in parallel. Alston also developed formal perturbative approaches not tied to any particular system. Materials studied included He + , Li 2+ , Be 3+ , B 4+ , C 5+ , and the H + + Na system

Solution-phase parallel synthesis of aryloxyimino amides via a novel multicomponent reaction among aromatic (Z)-chlorooximes, isocyanides, and electron-deficient phenols.

Science.gov (United States)

Mercalli, Valentina; Giustiniano, Mariateresa; Del Grosso, Erika; Varese, Monica; Cassese, Hilde; Massarotti, Alberto; Novellino, Ettore; Tron, Gian Cesare

2014-11-10

A library of 41 aryloxyimino amides was prepared via solution phase parallel synthesis by extending the multicomponent reaction of (Z)-chlorooximes and isocyanides to the use of electron-deficient phenols. The resulting aryloxyiminoamide derivatives can be used as intermediates for the synthesis of benzo[d]isoxazole-3-carboxamides, dramatically reducing the number of synthetic steps required by other methods reported in literature.

Preliminary report of numerical simulatons of intermediate wavelength collisional Rayleigh-Taylor instability in equatorial spread F

International Nuclear Information System (INIS)

Keskinen, M.J.; Ossakow, S.L.; Chaturvedi, P.K.

1980-01-01

Computer simulations of the intermediate wavelength (100--1000 m) collisional Rayleigh-Taylor instability in local unstable regions of the postsunset bottomside (300 km) equatorial F region ionosphere have been performed. For ambient electron density gradient scale lengths L=5, 10, 15 km we find that the linearly unstable horizontal modes saturate by nonlinear generation of linearly damped vertical modes with the result that in the nonlinear regime, power laws are observed in the horizontal P(k/sub x/) proportional k/sub x//sup -n/ and vertical P(k/sub y/) proportional k/sub y//sup -n/ one-dimensional power spectra with n=2--2.5. These results are consistent both with in situ experimental data and with theoretical prediction

Kelvin probe microscopy and electronic transport measurements in reduced graphene oxide chemical sensors

Science.gov (United States)

Kehayias, Christopher E.; MacNaughton, Samuel; Sonkusale, Sameer; Staii, Cristian

2013-06-01

Reduced graphene oxide (RGO) is an electronically hybrid material that displays remarkable chemical sensing properties. Here, we present a quantitative analysis of the chemical gating effects in RGO-based chemical sensors. The gas sensing devices are patterned in a field-effect transistor geometry, by dielectrophoretic assembly of RGO platelets between gold electrodes deposited on SiO2/Si substrates. We show that these sensors display highly selective and reversible responses to the measured analytes, as well as fast response and recovery times (tens of seconds). We use combined electronic transport/Kelvin probe microscopy measurements to quantify the amount of charge transferred to RGO due to chemical doping when the device is exposed to electron-acceptor (acetone) and electron-donor (ammonia) analytes. We demonstrate that this method allows us to obtain high-resolution maps of the surface potential and local charge distribution both before and after chemical doping, to identify local gate-susceptible areas on the RGO surface, and to directly extract the contact resistance between the RGO and the metallic electrodes. The method presented is general, suggesting that these results have important implications for building graphene and other nanomaterial-based chemical sensors.

Kelvin probe microscopy and electronic transport measurements in reduced graphene oxide chemical sensors.

Science.gov (United States)

Kehayias, Christopher E; MacNaughton, Samuel; Sonkusale, Sameer; Staii, Cristian

2013-06-21

Reduced graphene oxide (RGO) is an electronically hybrid material that displays remarkable chemical sensing properties. Here, we present a quantitative analysis of the chemical gating effects in RGO-based chemical sensors. The gas sensing devices are patterned in a field-effect transistor geometry, by dielectrophoretic assembly of RGO platelets between gold electrodes deposited on SiO2/Si substrates. We show that these sensors display highly selective and reversible responses to the measured analytes, as well as fast response and recovery times (tens of seconds). We use combined electronic transport/Kelvin probe microscopy measurements to quantify the amount of charge transferred to RGO due to chemical doping when the device is exposed to electron-acceptor (acetone) and electron-donor (ammonia) analytes. We demonstrate that this method allows us to obtain high-resolution maps of the surface potential and local charge distribution both before and after chemical doping, to identify local gate-susceptible areas on the RGO surface, and to directly extract the contact resistance between the RGO and the metallic electrodes. The method presented is general, suggesting that these results have important implications for building graphene and other nanomaterial-based chemical sensors.

Low-energy consequences of superstring-inspired models with intermediate-mass scales

International Nuclear Information System (INIS)

Gabbiani, F.

1987-01-01

The phenomenological consequences of implementing intermediate-mass scales in E 6 superstring-inspired models are discussed. Starting from a suitable Calabi-Yau compactification with b 1,1 >1, one gets, after Hosotani breaking, the rank r=5 gauge group SU(3) C x SU(2) L x U(1) Y x U(1) E , that is broken at an intermediate-mass scale down to the standard-model group. The analysis of both the intermediate and the electroweak breaking is performed in the two cases Λ c = M x and Λ c x , where Λ c is the scale at which the hidden sector gauginos condensate. It is performed quantitatively the minimization of the low-energy effective potential and the renormalization group analysis, yielding a viable set of mass spectra and confirming the reliability of the intermediate-breaking scheme

Species associations among larval helminths in an amphipod intermediate host.

Science.gov (United States)

Dezfuli, B S; Giari, L; Poulin, R

2000-10-01

Larval helminths that share the same intermediate host may or may not also share the same definitive hosts. If one or more of these helminth species can manipulate the phenotype of the intermediate host, there can be great advantages or severe costs for other helminths resulting from co-occurring with a manipulator, depending on whether they have the same definitive host or not. Among 2372 specimens of the amphipod Echinogammarus stammeri collected from the river Brenta, northern Italy, there was a positive association between two acanthocephalan species with the same fish definitive hosts, the relatively common Pomphorhynchus laevis and the much less prevalent Acanthocephalus clavula. The number of cystacanths of P. laevis per infected amphipod, which ranged from one to five, did not influence the likelihood that the amphipod would also host A. clavula. A third acanthocephalan species, Polymorphus minutus,which matures in birds, showed no association with either of the two other species. These results show that associations among helminth species in intermediate hosts are not random, and are instead the product of selection favouring certain pathways of transmission.

One-electron standard reduction potentials of nitroaromatic and cyclic nitramine explosives

International Nuclear Information System (INIS)

Uchimiya, Minori; Gorb, Leonid; Isayev, Olexandr; Qasim, Mohammad M.; Leszczynski, Jerzy

2010-01-01

Extensive studies have been conducted in the past decades to predict the environmental abiotic and biotic redox fate of nitroaromatic and nitramine explosives. However, surprisingly little information is available on one-electron standard reduction potentials (E o (R-NO 2 /R-NO 2 - )). The E o (R-NO 2 /R-NO 2 - ) is an essential thermodynamic parameter for predicting the rate and extent of reductive transformation for energetic residues. In this study, experimental (linear free energy relationships) and theoretical (ab initio calculation) approaches were employed to determine E o (R-NO 2 /R-NO 2 - ) for nitroaromatic, (caged) cyclic nitramine, and nitroimino explosives that are found in military installations or are emerging contaminants. The results indicate a close agreement between experimental and theoretical E o (R-NO 2 /R-NO 2 - ) and suggest a key trend: E o (R-NO 2 /R-NO 2 - ) value decreases from di- and tri-nitroaromatic (e.g., 2,4-dinitroanisole) to nitramine (e.g., RDX) to nitroimino compound (e.g., nitroguanidine). The observed trend in E o (R-NO 2 /R-NO 2 - ) agrees with reported rate trends for reductive degradation, suggesting a thermodynamic control on the reduction rate under anoxic/suboxic conditions. - Reduction of explosives becomes less thermodynamically favorable as the one-electron standard reduction potential decreases from di- and tri-nitroaromatic, nitramine, to nitroimino compounds.

Dimers of nineteen-electron sandwich compounds: Crystal and electronic structures, and comparison of reducing strengths

KAUST Repository

Mohapatra, Swagat Kumar

2014-10-03

The dimers of some Group 8 metal cyclopentadienyl/ arene complexes and Group 9 metallocenes can be handled in air, yet are strongly reducing, making them useful n-dopants in organic electronics. In this work, the Xray molecular structures are shown to resemble those of Group 8 metal cyclopentadienyl/pentadienyl or Group 9 metal cyclopentadienyl/diene model compounds. Compared to those of the model compounds, the DFT HOMOs of the dimers are significantly destabilized by interactions between the metal and the central C-C σ-bonding orbital, accounting for the facile oxidation of the dimers. The lengths of these C-C bonds (X-ray or DFT) do not correlate with DFT dissociation energies, the latter depending strongly on the monomer stabilities. Ru and Ir monomers are more reducing than their Fe and Rh analogues, but the corresponding dimers also exhibit much higher dissociation energies, so the estimated monomer cation/neutral dimer potentials are, with the exception of that of [RhCp2]2, rather similar (-1.97 to-2.15 V vs. FeCp2 +/0 in THF). The consequences of the variations in bond strength and redox potentials for the reactivity of the dimers are discussed.

Dimers of nineteen-electron sandwich compounds: Crystal and electronic structures, and comparison of reducing strengths

KAUST Repository

Mohapatra, Swagat Kumar; Fonari, Alexandr; Risko, Chad; Yesudas, Kada; Moudgil, Karttikay; Delcamp, Jared Heath; Timofeeva, Tatiana V.; Bredas, Jean-Luc; Marder, Seth R.; Barlow, Stephen J.

2014-01-01

The dimers of some Group 8 metal cyclopentadienyl/ arene complexes and Group 9 metallocenes can be handled in air, yet are strongly reducing, making them useful n-dopants in organic electronics. In this work, the Xray molecular structures are shown to resemble those of Group 8 metal cyclopentadienyl/pentadienyl or Group 9 metal cyclopentadienyl/diene model compounds. Compared to those of the model compounds, the DFT HOMOs of the dimers are significantly destabilized by interactions between the metal and the central C-C σ-bonding orbital, accounting for the facile oxidation of the dimers. The lengths of these C-C bonds (X-ray or DFT) do not correlate with DFT dissociation energies, the latter depending strongly on the monomer stabilities. Ru and Ir monomers are more reducing than their Fe and Rh analogues, but the corresponding dimers also exhibit much higher dissociation energies, so the estimated monomer cation/neutral dimer potentials are, with the exception of that of [RhCp2]2, rather similar (-1.97 to-2.15 V vs. FeCp2 +/0 in THF). The consequences of the variations in bond strength and redox potentials for the reactivity of the dimers are discussed.

Antiferromagnetic iridium-manganese intermediate layers for perpendicular recording media (invited)

Science.gov (United States)

Srinivasan, Kumar; Piramanayagam, S. N.; Sbiaa, Rachid; Kay, Yew Seng; Tan, Hang Khume; Wong, Seng Kai

2009-04-01

Current generation of cobalt-oxide-based perpendicular magnetic recording media uses single or dual ruthenium intermediate layers in order to grow crystallographically textured, and magnetically isolated granular media. In this work, the potential advantages of an antiferromagnetic iridium-manganese intermediate layer directly under the recording layer are highlighted. Owing to its close lattice matching with hexagonal cobalt, iridium-manganese which has the L12, or AuCu3-type crystal structure, can support the heteroepitaxial growth of the cobalt-based recording layer. In one of the media schemes described here, (111) textured iridium-manganese thin film was grown on 7.5 nm thick ruthenium layer. On the iridium-manganese as segregation layer, the Co-oxide-based magnetic recording layer showed perpendicular texture with Δθ50 below 4°, coercivity of over 4000 Oe alongside magnetic exchange decoupling, average grain sizes of 6 nm with distributions under 14%, and improved thermal stability. Measurements of the anisotropy constant did not show any significant change and even an IrMn capping layer was observed to improve the thermal stability. The possible mechanisms through which the IrMn layer could affect the thermal stability are hypothesized. The initial layers of the magnetic recording layer on IrMn segregation layers also showed exchange-decoupled and segregated grains, which is unlike that observed on Ru segregation layers. In a second media scheme, (111) textured iridium-manganese thin film was grown on a crystalline soft magnetic underlayer belonging on top of amorphous soft underlayers. In this scheme, partial pinning of the soft underlayer due to exchange-bias interaction with the IrMn layer was observed. This scheme offers the possibility to reduce the intermediate layer thickness, thus improve media writability, and with further optimization, could potentially facilitate the approach toward 1 Tbits/in.2.

Information acquisition and financial intermediation

OpenAIRE

Boyarchenko, Nina

2012-01-01

This paper considers the problem of information acquisition in an intermediated market, where the specialists have access to superior technology for acquiring information. These informational advantages of specialists relative to households lead to disagreement between the two groups, changing the shape of the intermediation-constrained region of the economy and increasing the frequency of periods when the intermediation constraint binds. Acquiring the additional information is, however, cost...

Influence of an Intermediate Option on the Description-Experience Gap and Information Search.

Science.gov (United States)

Sharma, Neha; Debnath, Shoubhik; Dutt, Varun

2018-01-01

Research shows that people tend to overweight small probabilities in description and underweight them in experience, thereby leading to a different pattern of choices between description and experience; a phenomenon known as the Description-Experience (DE) gap. However, little is known on how the addition of an intermediate option and contextual framing influences the DE gap and people's search strategies. This paper tests the effects of an intermediate option and contextual framing on the DE gap and people's search strategies, where problems require search for information before a consequential choice. In the first experiment, 120 participants made choice decisions across investment problems that differed in the absence or presence of an intermediate option. Results showed that adding an intermediate option did not reduce the DE gap on the maximizing option across a majority of problems. There were a large majority of choices for the intermediate option. Furthermore, there was an increase in switching between options due to the presence of the intermediate option. In the second experiment, 160 participants made choice decisions in problems like those presented in experiment 1; however, problems lacked the investment framing. Results replicated findings from the first experiment and showed a similar DE gap on the maximizing option in a majority of problems in both the absence and presence of the intermediate option. Again, there were a large majority of choices for the intermediate option. Also, there was an increase in switching between options due to the presence of the intermediate option. Meta-analyses revealed that the absence or presence of the intermediate option created certain differences in the strength of frequency and recency processes. Also, a single natural-mean heuristic model was able to account for the experimental results across both experiments. We discuss implications of our findings to consequential decisions made after information search.

Influence of an Intermediate Option on the Description-Experience Gap and Information Search

Directory of Open Access Journals (Sweden)

Neha Sharma

2018-03-01

Full Text Available Research shows that people tend to overweight small probabilities in description and underweight them in experience, thereby leading to a different pattern of choices between description and experience; a phenomenon known as the Description-Experience (DE gap. However, little is known on how the addition of an intermediate option and contextual framing influences the DE gap and people’s search strategies. This paper tests the effects of an intermediate option and contextual framing on the DE gap and people’s search strategies, where problems require search for information before a consequential choice. In the first experiment, 120 participants made choice decisions across investment problems that differed in the absence or presence of an intermediate option. Results showed that adding an intermediate option did not reduce the DE gap on the maximizing option across a majority of problems. There were a large majority of choices for the intermediate option. Furthermore, there was an increase in switching between options due to the presence of the intermediate option. In the second experiment, 160 participants made choice decisions in problems like those presented in experiment 1; however, problems lacked the investment framing. Results replicated findings from the first experiment and showed a similar DE gap on the maximizing option in a majority of problems in both the absence and presence of the intermediate option. Again, there were a large majority of choices for the intermediate option. Also, there was an increase in switching between options due to the presence of the intermediate option. Meta-analyses revealed that the absence or presence of the intermediate option created certain differences in the strength of frequency and recency processes. Also, a single natural-mean heuristic model was able to account for the experimental results across both experiments. We discuss implications of our findings to consequential decisions made after

Interplay between one-body and two-body dynamics in the subthreshold pion production at intermediate energies

International Nuclear Information System (INIS)

Cassing, W.

1984-12-01

The role of the time-dependent mean field in subthreshold pion production by first chance nucleon-nucleon collisions is studied for heavy-ion reactions at intermediate energies in a finite two-center shell model. It is found that the energy distribution of the nucleons for overlapping ions can roughly be approximated by shifted groundstate momentum distributions using a quasi-free dispersion relation. The absolute cross sections for the production of neutron pions can be reproduced from 35 MeV/u to 150 MeV/u. (orig.)

Coalescence of two polarized photons with antiparallel momenta into one on an electron

International Nuclear Information System (INIS)

Galynskii, M.V.

1989-01-01

The matrix elements have been calculated for the coalescence of two photons with antiparallel momenta and equal frequencies into one on an electron. An explicit expression for the differential probability for the process, with allowance for the polarization of all the particles, has been obtained in the nonrelativistic approximation

The reduction of nitrate, nitrite and hydroxylamine to ammonia by enzymes from Cucurbita pepo L. in the presence of reduced benzyl viologen as electron donor

Science.gov (United States)

Cresswell, C. F.; Hageman, R. H.; Hewitt, E. J.; Hucklesby, D. P.

1965-01-01

1. Enzyme systems from Cucurbita pepo have been shown to catalyse the reduction of nitrite and hydroxylamine to ammonia in yields about 90–100%. 2. Reduced benzyl viologen serves as an efficient electron donor for both systems. Activity of the nitrite-reductase system is directly related to degree of dye reduction when expressed in terms of the function for oxidation–reduction potentials, but appears to decrease to negligible activity below about 9% dye reduction. 3. NADH and NADPH alone produce negligible nitrite loss, but NADPH can be linked to an endogenous diaphorase system to reduce nitrite to ammonia in the presence of catalytic amounts of benzyl viologen. 4. The NADH– or NADPH–nitrate-reductase system that is also present can accept electrons from reduced benzyl viologen, but shows relationships opposite to that for the nitrite-reductase system with regard to effect of degree of dye reduction on activity. The product of nitrate reduction may be nitrite alone, or nitrite and ammonia, or ammonia alone, according only to the degree of dye reduction. 5. The relative activities of nitrite-reductase and hydroxylamine-reductase systems show different relationships with degree of dye reduction and may become reversed in magnitude when effects of degree of dye reduction are tested over a suitable range. 6. Nitrite severely inhibits the rate of reduction of hydroxylamine without affecting the yield of ammonia as a percentage of total substrate loss, but hydroxylamine has a negligible effect on the activity of the nitrite-reductase system. 7. The apparent Km for nitrite (1 μm) is substantially less than that for hydroxylamine, for which variable values between 0·05 and 0·9mm (mean 0·51 mm) have been observed. 8. The apparent Km values for reduced benzyl viologen differ for the nitrite-reductase and hydroxylamine-reductase systems: 60 and 7·5 μm respectively. 9. It is concluded that free hydroxylamine may not be an intermediate in the reduction of nitrite

Observation of the muonic decay of the charged intermediate vector boson

International Nuclear Information System (INIS)

Arnison, G.; Astbury, A.; Grayer, G.; Haynes, W.J.; Nandi, A.K.; Roberts, C.; Scott, W.; Shah, T.P.; Bezaguet, A.; Bock, R.K.; Calvetti, M.; Cennini, P.; Cittolin, S.; Dallman, D.; Demoulin, M.; DiBitonto, D.; Ellis, N.; Hoffmann, H.; Jank, W.; Jorat, G.; Leveque, A.; Maurin, G.; Muller, F.; Naumann, L.; Norton, A.; Pauss, F.; Placci, A.; Porte, J.P.; Revol, J.P.; Rijssenbeek, M.; Rossi, P.; Rubbia, C.; Sadoulet, B.; Schinzel, D.; Sumorok, K.; Timmer, J.; Vuillemin, V.; Xie, Y.G.; Zurfluh, E.; Kryn, D.; Cochet, C.; DeBeer, M.; Denegri, D.; Givernaud, A.; Laugier, J.P.; Locci, E.; Malosse, J.J.; Rich, J.; Sass, J.; Saudraix, J.; Savoy-Navarro, A.; Spiro, M.; Dobrzynski, L.; Fontaine, G.; Ghesquiere, C.; Giraud-Heraud, Y.; Mendiburu, J.P.; Orkin-Lecourtois, A.; Sajot, G.; Tao, C.; Vrana, J.; Hertzberger, L.O.; Holthuizen, D.J.; Eijk, B. van; Bacci, C.; Ceradini, F.; Di Ciaccio, A.; Lacava, F.; Moricca, M.; Paoluzi, L.; Piano Mortari, G.; Salvini, G.; Bauer, G.; Cline, D.; Markiewicz, T.; Mohammadi, M.; Centro, S.; Corden, M.; Dowell, J.D.; Garvey, J.; Homer, R.J.; Kenyon, I.; McMahon, T.; Streets, J.; Watkins, P.; Wilson, J.; Eggert, K.; Erhard, P.; Faissner, H.; Giboni, K.L.; Hansl-Kozanecka, T.; Hoffmann, D.; Lehmann, H.; Leuchs, R.; Radermacher, E.; Reithler, H.; Tscheslog, E.; Fincke, M.; Muirhead, H.; Frey, R.; Kernan, A.; Kozanecki, W.; Morgan, K.; Ransdell, J.; Smith, D.; Fruehwirth, R.; Dallman, D.; Strauss, J.; Szoncso, F.; Wahl, H.D.; Wulz, C.E.; Geer, S.; Rohlf, J.; Karimaeki, V.; Kinnunen, R.; Pietarinen, E.; Pimiae, M.; Tuominiemi, J.

1984-01-01

Muons of high transverse momentum psub(T)sup(μ) have been observed in the large drift chambers surrounding the UA1 detector at the CERN 540 GeV panti p collider. For an integrated luminosity of 108 nb -1 , 14 isolated muons have been found with psub(T) > 15 GeV/c. They are correlated with a large imbalance in total transverse energy, and show a kinematic behaviour consistent with the muonic decay of the Intermediate Vector Boson Wsup(+-) of weak interactions. The partial cross section is in agreement with previous measurements for electronic decays and with muon-electron universality. The W mass is determined to be msub(W) = 81sub(-7) +6 GeV/c 2 . (orig.)

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

Reducing charging effects in scanning electron microscope images by Rayleigh contrast stretching method (RCS).

Science.gov (United States)

Wan Ismail, W Z; Sim, K S; Tso, C P; Ting, H Y

2011-01-01

To reduce undesirable charging effects in scanning electron microscope images, Rayleigh contrast stretching is developed and employed. First, re-scaling is performed on the input image histograms with Rayleigh algorithm. Then, contrast stretching or contrast adjustment is implemented to improve the images while reducing the contrast charging artifacts. This technique has been compared to some existing histogram equalization (HE) extension techniques: recursive sub-image HE, contrast stretching dynamic HE, multipeak HE and recursive mean separate HE. Other post processing methods, such as wavelet approach, spatial filtering, and exponential contrast stretching, are compared as well. Overall, the proposed method produces better image compensation in reducing charging artifacts. Copyright © 2011 Wiley Periodicals, Inc.

One-electron reduction of anthraquinone sulphonates: a pulse radiolysis study

International Nuclear Information System (INIS)

Pal, H.; Palit, D.K.; Mukherjee, T.; Mittal, J.P.

1991-01-01

Semiquinone free radicals, derived from 2-sulphonate, 1,5-disulphonate and 2,6-disulphonate derivatives of 9,10-anthraquinone, have been studied using pulse radiolysis and kinetic absorption spectrophotometry techniques. Spectroscopic characteristics of both neutral and anionic species have been ascertained. Kinetics of formation and decay, reactivity with oxygen and one-electron reduction potential values have been estimated. The semiquinone radicals have been shown to be very stable under suitable pH conditions where the equilibrium (2 semiquinone ↔ quinone + hydroquinone) lies predominantly to the left. From a measurement of the equilibrium constants at different pH, values of E 2 and E m have been calculated. (author)

Development and application of a 2-electron reduced density matrix approach to electron transport via molecular junctions

Science.gov (United States)

Hoy, Erik P.; Mazziotti, David A.; Seideman, Tamar

2017-11-01

Can an electronic device be constructed using only a single molecule? Since this question was first asked by Aviram and Ratner in the 1970s [Chem. Phys. Lett. 29, 277 (1974)], the field of molecular electronics has exploded with significant experimental advancements in the understanding of the charge transport properties of single molecule devices. Efforts to explain the results of these experiments and identify promising new candidate molecules for molecular devices have led to the development of numerous new theoretical methods including the current standard theoretical approach for studying single molecule charge transport, i.e., the non-equilibrium Green's function formalism (NEGF). By pairing this formalism with density functional theory (DFT), a wide variety of transport problems in molecular junctions have been successfully treated. For some systems though, the conductance and current-voltage curves predicted by common DFT functionals can be several orders of magnitude above experimental results. In addition, since density functional theory relies on approximations to the exact exchange-correlation functional, the predicted transport properties can show significant variation depending on the functional chosen. As a first step to addressing this issue, the authors have replaced density functional theory in the NEGF formalism with a 2-electron reduced density matrix (2-RDM) method, creating a new approach known as the NEGF-RDM method. 2-RDM methods provide a more accurate description of electron correlation compared to density functional theory, and they have lower computational scaling compared to wavefunction based methods of similar accuracy. Additionally, 2-RDM methods are capable of capturing static electron correlation which is untreatable by existing NEGF-DFT methods. When studying dithiol alkane chains and dithiol benzene in model junctions, the authors found that the NEGF-RDM predicts conductances and currents that are 1-2 orders of magnitude below

Another intermediate in the photochemistry and radiation chemistry of alkaline aqueous solutions

International Nuclear Information System (INIS)

Telser, T.; Schindewolf, U.

1985-01-01

By UV flash photolytic and pulse radiolytic experiments of aqueous alkaline solutions we confirm older experiments of Walker et al. and Hart et al., showing that the decay of hydrated electrons gives rise to another intermediate X which by light absorption revives hydrated electrons again. X is formed by a reaction of 1. order with respect to hydrated electrons, the rate of its formation increases with pH, and it decays by a second order process with a rate constant not exceeding 5 . 10 9 M -1 sec -1 , probably leading to hydrogen (e - ->X; 2X->H 2 ). X has maximum light absorption around 270 nm with an extinction coefficient of about 5000 M -1 cm -1 . We will not speculate about the nature of X. (orig.)

''Super-radiant'' states in intermediate energy nuclear physics

International Nuclear Information System (INIS)

Auerbach, N.

1994-01-01

A ''super-radiant'' state emerges when, under certain conditions, one or a few ''internal'' states acquire a large collective decay width due to the coupling to one or a few ''external'' decay channels. The rest of the internal states are ''stripped'' of their decay width and become long lived quasistationary states. The essentials of such mechanism and its possible role in intermediate energy nuclear physics are discussed in this work

Results of intermediate-scale hot isostatic press can experiments

International Nuclear Information System (INIS)

Nelson, L.O.; Vinjamuri, K.

1995-05-01

Radioactive high-level waste (HLW) has been managed at the Idaho Chemical Processing Plant (ICPP) for a number of years. Since 1963, liquid HLW has been solidified into a granular solid (calcine). Presently, over 3,800 m 3 of calcine is stored in partially-underground stainless steel bins. Four intermediate- scale HLW can tests (two 6-in OD x 12-in tall and two 4-in OD x 7-in tall) are described and compared to small-scale HIP can tests (1- to 3-in OD x 1- to 4.5-in tall). The intermediate-scale HIP cans were loaded with a 70/30 calcine/frit blend and HIPped at an off-site facility at 1050 degrees C; and 20 ksi. The dimensions of two cans (4-in OD x 7-in tall) were monitored during the HIP cycle with eddy-current sensors. The sensor measurements indicated that can deformation occurs rapidly at 700 degrees C; after which, there is little additional can shrinkage. HIP cans were subjected to a number of analyses including calculation of the overall packing efficiency (56 to 59%), measurement of glass-ceramic (3.0 to 3.2 g/cc), 14-day MCC-1 leach testing (total mass loss rates 2 day), and scanning electron microscopy (SEM). Based on these analyses, the glass-ceramic material produced in intermediate-scale cans is similar to material produced in small-scale cans. No major scale-up problems were indicated. Based on the packing efficiency observed in intermediate- and small-scale tests, the overall packing efficiency of production-scale (24-in OD x 36- to 190-in tall) cans would be approximately 64% for a pre-HIP right-circular cylinder geometry. An efficiency of 64% would represent a volume reduction factor of 2.5 over a candidate glass waste prepared at 33 wt% waste loading

Peroxynitrite efficiently mediates the interconversion of redox intermediates of myeloperoxidase

International Nuclear Information System (INIS)

Furtmueller, Paul Georg; Jantschko, Walter; Zederbauer, Martina; Schwanninger, Manfred; Jakopitsch, Christa; Herold, Susanna; Koppenol, Willem H.; Obinger, Christian

2005-01-01

Nitric oxide-derived oxidants (e.g., peroxynitrite) are believed to participate in antimicrobial activities as part of normal host defenses but also in oxidative tissue injury in inflammatory disorders. A similar role is ascribed to the heme enzyme myeloperoxidase (MPO), the most abundant protein of polymorphonuclear leukocytes, which are the terminal phagocytosing effector cells of the innate immune system. Concomitant production of peroxynitrite and release of millimolar MPO are characteristic events during phagocytosis. In order to understand the mode of interaction between MPO and peroxynitrite, we have performed a comprehensive stopped-flow investigation of the reaction between all physiological relevant redox intermediates of MPO and peroxynitrite. Both iron(III) MPO and iron(II) MPO are rapidly converted to compound II by peroxynitrite in monophasic reactions with calculated rate constants of (6.8 ± 0.1) x 10 6 M -1 s -1 and (1.3 ± 0.2) x 10 6 M -1 s -1 , respectively (pH 7.0 and 25 deg C). Besides these one- and two-electron reduction reactions of peroxynitrite, which produce nitrogen dioxide and nitrite, a one-electron oxidation to the oxoperoxonitrogen radical must occur in the fast monophasic transition of compound I to compound II mediated by peroxynitrite at pH 7.0 [(7.6 ± 0.1) x 10 6 M -1 s -1 ]. In addition, peroxynitrite induced a steady-state transition from compound III to compound II with a rate of (1.0 ± 0.3) x 10 4 M -1 s -1 . Thus, the interconversion among the various oxidation states of MPO that is prompted by peroxynitrite is remarkable. Reaction mechanisms are proposed and the physiological relevance is discussed

One-pot synthesis of reduced graphene oxide supported PtCuy catalysts with enhanced electro-catalytic activity for the methanol oxidation reaction

International Nuclear Information System (INIS)

Peng, Xinglan; Zhao, Yanchun; Chen, Duhong; Fan, Yanfang; Wang, Xiao; Wang, Weili; Tian, Jianniao

2014-01-01

The outstanding performance PtCu y (y = 1,2,3) alloy nanoparticles supported on reduced graphene oxide (rGO) have been synthesized by a facile, efficient, one-pot hydrothermal synthesis approach. The as-prepared PtCu y /rGO catalysts are comprehensively characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy. Cyclic voltammetry, CO-stripping voltammetry and chronoamperometry results reveal that the PtCu y /rGO catalysts have higher electro-catalytic activity, more negative onset oxidative potential, more excellent tolerance ability for CO poisoning and enhanced stability for the electro-oxidation of methanol compared to pure Pt/rGO. As far as the as-made PtCu y /rGO catalysts are concerned, the PtCu 2 /rGO exhibits the highest electro-catalytic activity. The mechanism of the promoting effect of Cu on Pt is explained based on the electronic modification effect. The nature of interfacial interactions between the Pt-Cu active metal phase and the rGO supporting materials is crucial to achieving high performance

The Stern-Gerlach experiment, electron spin and intermediate quantum mechanics

International Nuclear Information System (INIS)

Mackintosh, A.R.

1983-01-01

The paper deals with the theory of electron spin. The Stern-Gerlach experiment, the anticommutation relations and the properties of spin operators are discussed. The Pauli theory, Dirac transformation theory, the double Stern-Gerlach experiment, the EPR paradox and Bell's inequality are also covered. (U.K.)

Transport of excess electrons in dense dielectric fluids. Phenomenological interpretation and application to a one-dimensional argon fluid

International Nuclear Information System (INIS)

Leycuras, A.; Larour, J.

1978-01-01

The main results about the drift velocities of excess electrons in dense argon are summarized. The weaknesses of the available theories are mainly due to poor information concerning the electron-atom potential during an atom-atom collision. The drift velocities, as a function of the applied electric field present the following features at high fields: the drift velocity reaches a limit that is at most one order of magnitude larger than the sound velocity at the same density. These remarks and the attractive nature of the electron-atom potential suggest a transport model, the collisional transfer model analog to the one applied to the determination of the sound velocity. Drift velocities obtained with this model applied to a one-dimensional molecular dynamics simulation are presented [fr

Resonant tunneling and persistent current of a non-interacting and weakly interacting one-dimensional electron gas

International Nuclear Information System (INIS)

Krive, I.V.; Sandstroem, P.

1997-01-01

The persistent current for a one-dimensional ring with two tunneling barriers is considered in the limit of weakly interacting electrons. In addition to small off-resonance current, there are two kinds of resonant behaviour; (i) a current independent of the barrier transparency (true resonance) and (ii) a current analogous to the one for a ring with only single barrier (''semi''-resonance). For a given barrier transparency the realization of this or that type of resonant behaviour depends both on the geometrical factor (the ratio of interbarrier distance to a ring circumference) and on the strength of electron-electron interaction. It is shown that repulsive interaction favours the ''semi''-resonance behaviour. For a small barrier transparency the ''semi''-resonance peaks are easily washed out by temperature whereas the true resonance peaks survive. (author). 22 refs, 2 figs

Phase competition in a one-dimensional three-orbital Hubbard-Holstein model

Science.gov (United States)

Li, Shaozhi; Tang, Yanfei; Maier, Thomas A.; Johnston, Steven

2018-05-01

We study the interplay between the electron-phonon (e -ph) and on-site electron-electron (e-e) interactions in a three-orbital Hubbard-Holstein model on an extended one-dimensional lattice using determinant quantum Monte Carlo. For weak e-e and e -ph interactions, we observe a competition between an orbital-selective Mott phase (OSMP) and a (multicomponent) charge-density-wave (CDW) insulating phase, with an intermediate metallic phase located between them. For large e-e and e -ph couplings, the OSMP and CDW phases persist, while the metallic phase develops short-range orbital correlations and becomes insulating when both the e-e and e -ph interactions are large but comparable. Many of our conclusions are in line with those drawn from a prior dynamical mean-field theory study of the two-orbital Hubbard-Holstein model [Phys. Rev. B 95, 121112(R) (2017), 10.1103/PhysRevB.95.121112] in infinite dimension, suggesting that the competition between the e -ph and e-e interactions in multiorbital Hubbard-Holstein models leads to rich physics, regardless of the dimension of the system.

Time-resolved resonance Raman spectroscopy of intermediates of bacteriorhodopsin: The bK(590) intermediate.

Science.gov (United States)

Terner, J; Hsieh, C L; Burns, A R; El-Sayed, M A

1979-07-01

We have combined microbeam and flow techniques with computer subtraction methods to obtain the resonance Raman spectrum of the short lived batho-intermediate (bK(590)) of bacteriorhodopsin. Comparison of the spectra obtained in (1)H(2)O and (2)H(2)O, as well as the fact that the bK(590) intermediate shows large optical red shifts, suggests that the Schiff base linkage of this intermediate is protonated. The fingerprint region of the spectrum of bK(590), sensitive to the isomeric configuration of the retinal chromophore, does not resemble the corresponding region of the parent bR(570) form. The resonance Raman spectrum of bK(590) as well as the spectra of all of the other main intermediates in the photoreaction cycle of bacteriorhodopsin are discussed and compared with resonance Raman spectra of published model compounds.

One electron reduction of acridine orange studied in aqueous micellar medium using pulse radiolysis technique

International Nuclear Information System (INIS)

Goel, Anjali; Guha, S.N.

1994-01-01

Absorption spectrum, decay and formation kinetics of semi reduced species formed by the reaction of hydrated electron (e aq - ) with acridine orange (AO) were evaluated in sodium lauryl sulphate (SLS) micellar medium. Fluorescence and absorption properties of AO were also studied in this micellar system. The results were compared with those in homogenous aqueous medium. (author). 2 refs., 2 figs

One-electron standard reduction potentials of nitroaromatic and cyclic nitramine explosives

Energy Technology Data Exchange (ETDEWEB)

Uchimiya, Minori, E-mail: sophie.uchimiya@ars.usda.go [Environmental Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180 (United States); Gorb, Leonid [SpecPro Inc, 3909 Halls Ferry Road, Vicksburg, MS 39180 (United States); Isayev, Olexandr [Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106 (United States); Qasim, Mohammad M. [Environmental Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180 (United States); Leszczynski, Jerzy [Environmental Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180 (United States); Interdisciplinary Center for Nanotoxicity, Jackson State University, Jackson, MS 39217 (United States)

2010-10-15

Extensive studies have been conducted in the past decades to predict the environmental abiotic and biotic redox fate of nitroaromatic and nitramine explosives. However, surprisingly little information is available on one-electron standard reduction potentials (E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -})). The E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -}) is an essential thermodynamic parameter for predicting the rate and extent of reductive transformation for energetic residues. In this study, experimental (linear free energy relationships) and theoretical (ab initio calculation) approaches were employed to determine E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -}) for nitroaromatic, (caged) cyclic nitramine, and nitroimino explosives that are found in military installations or are emerging contaminants. The results indicate a close agreement between experimental and theoretical E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -}) and suggest a key trend: E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -}) value decreases from di- and tri-nitroaromatic (e.g., 2,4-dinitroanisole) to nitramine (e.g., RDX) to nitroimino compound (e.g., nitroguanidine). The observed trend in E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -}) agrees with reported rate trends for reductive degradation, suggesting a thermodynamic control on the reduction rate under anoxic/suboxic conditions. - Reduction of explosives becomes less thermodynamically favorable as the one-electron standard reduction potential decreases from di- and tri-nitroaromatic, nitramine, to nitroimino compounds.

Role of Intermediate Filaments in Vesicular Traffic

Directory of Open Access Journals (Sweden)

Azzurra Margiotta

2016-04-01

Full Text Available Intermediate filaments are an important component of the cellular cytoskeleton. The first established role attributed to intermediate filaments was the mechanical support to cells. However, it is now clear that intermediate filaments have many different roles affecting a variety of other biological functions, such as the organization of microtubules and microfilaments, the regulation of nuclear structure and activity, the control of cell cycle and the regulation of signal transduction pathways. Furthermore, a number of intermediate filament proteins have been involved in the acquisition of tumorigenic properties. Over the last years, a strong involvement of intermediate filament proteins in the regulation of several aspects of intracellular trafficking has strongly emerged. Here, we review the functions of intermediate filaments proteins focusing mainly on the recent knowledge gained from the discovery that intermediate filaments associate with key proteins of the vesicular membrane transport machinery. In particular, we analyze the current understanding of the contribution of intermediate filaments to the endocytic pathway.

Intermediality: Bridge to Critical Media Literacy.

Science.gov (United States)

Pailliotet, Ann Watts; Semali, Ladislaus; Rodenberg, Rita K.; Giles, Jackie K.; Macaul, Sherry L.

2000-01-01

Defines "intermediality" as the ability to critically read and write with and across varied symbol systems. Relates it to critical media literacy. Offers rationales for teaching critical media literacy in general, and intermedial instruction in particular. Identifies seven guiding intermedial elements: theory, texts, processes, contexts,…

Spin entanglement in elastic electron scattering from quasi-one electron atoms

Science.gov (United States)

Fonseca Dos Santos, Samantha; Bartschat, Klaus

2017-04-01

We have extended our work on e-Li collisions to investigate low-energy elastic electron collisions with atomic hydrogen and other alkali targets (Na,K,Rb). These systems have been suggested for the possibility of continuously varying the degree of entanglement between the elastically scattered projectile and the valence electron. In order to estimate how well such a scheme may work in practice, we carried out overview calculations for energies between 0 and 10 eV and the full range of scattering angles 0° -180° . In addition to the relative exchange asymmetry parameter that characterizes the entanglement, we present the differential cross section in order to estimate whether the count rates in the most interesting energy-angle regimes are sufficient to make such experiments feasible in practice. Work supported by the NSF under PHY-1403245.

An Intermediate in the evolution of superfast sonic muscles

Directory of Open Access Journals (Sweden)

Mok Hin-Kiu

2011-11-01

Full Text Available Abstract Background Intermediate forms in the evolution of new adaptations such as transitions from water to land and the evolution of flight are often poorly understood. Similarly, the evolution of superfast sonic muscles in fishes, often considered the fastest muscles in vertebrates, has been a mystery because slow bladder movement does not generate sound. Slow muscles that stretch the swimbladder and then produce sound during recoil have recently been discovered in ophidiiform fishes. Here we describe the disturbance call (produced when fish are held and sonic mechanism in an unrelated perciform pearl perch (Glaucosomatidae that represents an intermediate condition in the evolution of super-fast sonic muscles. Results The pearl perch disturbance call is a two-part sound produced by a fast sonic muscle that rapidly stretches the bladder and an antagonistic tendon-smooth muscle combination (part 1 causing the tendon and bladder to snap back (part 2 generating a higher-frequency and greater-amplitude pulse. The smooth muscle is confirmed by electron microscopy and protein analysis. To our knowledge smooth muscle attachment to a tendon is unknown in animals. Conclusion The pearl perch, an advanced perciform teleost unrelated to ophidiiform fishes, uses a slow type mechanism to produce the major portion of the sound pulse during recoil, but the swimbladder is stretched by a fast muscle. Similarities between the two unrelated lineages, suggest independent and convergent evolution of sonic muscles and indicate intermediate forms in the evolution of superfast muscles.

Fingerprinting taste buds: intermediate filaments and their implication for taste bud formation.

OpenAIRE

Witt, M; Reutter, K; Ganchrow, D; Ganchrow, J R

2000-01-01

Intermediate filaments in taste organs of terrestrial (human and chick) as well as aquatic (Xenopus laevis) species were detected using immunohistochemistry and electron microscopy. During development, the potential importance of the interface between the taste bud primordium and non-gustatory adjacent tissues is evidenced by the distinct immunoreactivity of a subpopulation of taste bud cells for cytokeratins and vimentin. In human foetuses, the selective molecular marker for taste bud primor...

Electronic Structural Analysis of Copper(II)–TEMPO/ABNO Complexes Provides Evidence for Copper(I)–Oxoammonium Character

International Nuclear Information System (INIS)

Walroth, Richard C.; Miles, Kelsey C.; Lukens, James T.; MacMillan, Samantha N.; Stahl, Shannon S.; Lancaster, Kyle M.

2017-01-01

Copper/aminoxyl species are proposed as key intermediates in aerobic alcohol oxidation. Several possible electronic structural descriptions of these species are possible, and here we probe this issue by examining four crystallographically characterized Cu/aminoxyl halide complexes by Cu K-edge, Cu L 2,3 - edge, and Cl K-edge X-ray absorption spectroscopy. The mixing coefficients between Cu, aminoxyl, and halide orbitals are determined via these techniques with support from density functional theory. The emergent electronic structure picture reveals that Cu coordination confers appreciable oxoammonium character to the aminoxyl ligand. The computational methodology is extended to one of the putative intermediates invoked in catalytic Cu/aminoxyl-driven alcohol oxidation reactions, with similar findings. On the whole, the results have important implications for the mechanism of alcohol oxidation and the underlying basis for cooperativity in this co- catalyst system.

Pyrrolidin-2-one derivatives may reduce body weight in rats with diet-induced obesity.

Science.gov (United States)

Dudek, Magdalena; Knutelska, Joanna; Bednarski, Marek; Nowiński, Leszek; Zygmunt, Małgorzata; Kazek, Grzegorz; Mordyl, Barbara; Głuch-Lutwin, Monika; Zaręba, Paula; Kulig, Katarzyna; Sapa, Jacek

2016-04-05

Obesity affects an increasing number of individuals in the human population and significant importance is attached to research leading to the discovery of drug which would effectively reduce weight. The search for new drugs with anorectic activity and acting within the adrenergic system has attracted the interest of researchers. This study concerns the experimental effects on body weight of α2-adrenoceptor antagonists from the group of pyrrolidin-2-one derivatives in rats with diet-induced obesity. The intrinsic activity of the test compounds at the α-adrenoreceptors was tested. Obesity in rats was obtained by the use of fatty diet and then the influence of the test compounds on body weight, food and water intakes, lipid and glucose profiles and glycerol and cortisol levels were determinated. The effects of the compounds on locomotor activity, body temperature, blood pressure and heart rate were tested. One of the test compounds (1-(3-(4-phenylpiperazin-1-yl)propyl)pyrrolidin-2-one) reduces the animal's body weight and the amount of peritoneal adipose tissue during chronic administration, at the same time it does not cause significant adverse effects on the cardiovascular system. This compound decreases temperature and elevates glycerol levels and does not change the locomotor activity and cortisol level at anti-obese dose. Some derivatives of pyrrolidin-2-one that act as antagonists of the α2-adrenoreceptor may reduce body weight. Reducing body weight for 1-(3-(4-phenylpiperazin-1-yl)propyl)pyrrolidin-2-one can be associated with decrease in food intake, body fat reduction, reduction of blood glucose, and increased thermogenesis and lipolysis. This effect cannot be the result of changes in spontaneous activity or stress. Copyright © 2016 Elsevier B.V. All rights reserved.

One-step synthesis of free-standing α-Ni(OH)2 nanosheets on reduced graphene oxide for high-performance supercapacitors

Science.gov (United States)

Dong, Bitao; Zhou, Han; Liang, Jin; Zhang, Lusi; Gao, Guoxin; Ding, Shujiang

2014-10-01

In this work, a hierarchical hybrid structure of reduced graphene oxide (rGO) supported ultrathin α-Ni(OH)2 nanosheets (denoted as α-Ni(OH)2@rGO NSs) has been developed successfully via an environmentally friendly one-step solution method. The resulting product of α-Ni(OH)2@rGO NSs was further characterized by scanning electron microscope, transmission electron microscope, x-ray diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller. The ultrathin α-Ni(OH)2 nanosheets of around 6 nm in thickness are uprightly coated on the double sides of rGO substrate. When evaluated as electrodes for supercapacitors, the hybrid α-Ni(OH)2@rGO NSs demonstrate excellent supercapacitor performance and cycling stability, compared with the self-aggregated α-Ni(OH)2 powder. Even after 2000 cycles, the hybrid electrodes still can deliver a specific capacitance of 1300 F g-1 at the current density of 5 A g-1, corresponding to no capacity loss of the initial cycle. Such excellent electrochemical performance should be attributed to the ultrathin, free-standing, and hierarchical nanosheets of α-Ni(OH)2, which not only promote efficient charge transport and facilitate the electrolyte diffusion, but also prevent aggregation of electro-active materials effectively during the charge-discharge process.

One-step synthesis of free-standing α-Ni(OH)₂ nanosheets on reduced graphene oxide for high-performance supercapacitors.

Science.gov (United States)

Dong, Bitao; Zhou, Han; Liang, Jin; Zhang, Lusi; Gao, Guoxin; Ding, Shujiang

2014-10-31

In this work, a hierarchical hybrid structure of reduced graphene oxide (rGO) supported ultrathin α-Ni(OH)2 nanosheets (denoted as α-Ni(OH)2@rGO NSs) has been developed successfully via an environmentally friendly one-step solution method. The resulting product of α-Ni(OH)2@rGO NSs was further characterized by scanning electron microscope, transmission electron microscope, x-ray diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller. The ultrathin α-Ni(OH)2 nanosheets of around 6 nm in thickness are uprightly coated on the double sides of rGO substrate. When evaluated as electrodes for supercapacitors, the hybrid α-Ni(OH)2@rGO NSs demonstrate excellent supercapacitor performance and cycling stability, compared with the self-aggregated α-Ni(OH)2 powder. Even after 2000 cycles, the hybrid electrodes still can deliver a specific capacitance of 1300 F g(-1) at the current density of 5 A g(-1), corresponding to no capacity loss of the initial cycle. Such excellent electrochemical performance should be attributed to the ultrathin, free-standing, and hierarchical nanosheets of α-Ni(OH)2, which not only promote efficient charge transport and facilitate the electrolyte diffusion, but also prevent aggregation of electro-active materials effectively during the charge-discharge process.

Paleoproductivity and intermediate-water ventilation in the subarctic Northwest Pacific during the last deglaciation

Science.gov (United States)

Khim, B.; Ikehara, K.; Sagawa, T.; Shibahara, A.; Yamamoto, M.

2010-12-01

Laminated sediments during the last deglaciation in the subarctic North Pacific indicate significant depletion of dissolved oxygen concentration at intermediate water depths. Such a strong oxygen minimum zone results primarily from a combination of high surface water productivity and poor ventilation of intermediate waters. We investigated a variety of paleoclimatic proxies using about 8-m long piston core sediment (GH02-1030; 42o13.770N, 144o12.530E; water depth, 1212 m) obtained from the continental slope off Tokachi (eastern Hokkaido Island), which is the main path of the southwestward Oyashio Current in the subarctic Northwest Pacific. Laminated sediments were identified at the two horizons in the core GH02-1030; the upper one at 11.4-12.2 cal.kyr BP and the lower one at 14.1-14.7 cal.kyr BP, corresponding to Bølling-Allerød (B/A) and Preboreal (PB), respectively. Between these laminated layers, Younger Dryas occurred. Both laminated sediment layers are characterized by Bolivina tumida, B. pacifica, and Buliminella tenuata, indicating dysoxic bottom water conditions. Increased Mg/Ca-derived intermediate-water temperature and δ18OW values at B/A and PB periods suggest the poor ventilation of intermediate water because of the surface water freshening (i.e., decrease of surface-water salinity). UK'37-derived temperature record also supports the increase of surface-water temperature during B/A and PB intervals. During the last deglaciation, short-chain C14-C18 n-fatty acids, derived mainly from marine organisms, showed higher concentrations, indicating the increased surface-water production, and at the same time, abundant lignin reflected more contribution of terrigenous organic matter, supporting increased freshwater discharge. Variation of CaCO3 contents show remarkable double peaks, corresponding to B/A and PB periods, respectively, leading to the increase of TOC contents. Opal contents also follow similar pattern to CaCO3 contents, but are much less than the

Dimers of nineteen-electron sandwich compounds: crystal and electronic structures, and comparison of reducing strengths.

Science.gov (United States)

Mohapatra, Swagat K; Fonari, Alexandr; Risko, Chad; Yesudas, Kada; Moudgil, Karttikay; Delcamp, Jared H; Timofeeva, Tatiana V; Brédas, Jean-Luc; Marder, Seth R; Barlow, Stephen

2014-11-17

The dimers of some Group 8 metal cyclopentadienyl/arene complexes and Group 9 metallocenes can be handled in air, yet are strongly reducing, making them useful n-dopants in organic electronics. In this work, the X-ray molecular structures are shown to resemble those of Group 8 metal cyclopentadienyl/pentadienyl or Group 9 metal cyclopentadienyl/diene model compounds. Compared to those of the model compounds, the DFT HOMOs of the dimers are significantly destabilized by interactions between the metal and the central CC σ-bonding orbital, accounting for the facile oxidation of the dimers. The lengths of these CC bonds (X-ray or DFT) do not correlate with DFT dissociation energies, the latter depending strongly on the monomer stabilities. Ru and Ir monomers are more reducing than their Fe and Rh analogues, but the corresponding dimers also exhibit much higher dissociation energies, so the estimated monomer cation/neutral dimer potentials are, with the exception of that of [RhCp2 ]2 , rather similar (-1.97 to -2.15 V vs. FeCp2 (+/0) in THF). The consequences of the variations in bond strength and redox potentials for the reactivity of the dimers are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sputtering of thin and intermediately thick films of solid deuterium by keV electrons

DEFF Research Database (Denmark)

Svendsen, Winnie Edith; Thestrup Nielsen, Birgitte; Schou, Jørgen

1995-01-01

Sputtering of films of solid deuterium by keV electrons was studied in a cryogenic set-up. The sputtering yield shows a minimum yield of about 4 D2/electron for 1.5 and 2 keV electrons at a thickness slightly larger than the average projected range of the electrons. We suggest that the yield around...... the minimum represents the value closest to a bulk-yield induced by electron bombardment. It may also include contributions from the mechanisms that enhance the yield for thin and very thick films....

Determination of Intermediate Resonance Parameter with RMET21 for nTRACER

International Nuclear Information System (INIS)

Sohail, Muhammad; Kim, Myung Hyun

2012-01-01

Ray Tracing based code nTRACER is being developed in Seoul National University that has the capability of 3-dimensional whole core neutron transport calculation. As a part of development of multi-group neutron cross section library for nTRACER, the current work is intended to accurately determine intermediate resonance parameters. Beside the systematic calculation of subgroup parameters for resonance self shielding calculation, intermediate resonance parameters itself can be as important as the multi-group neutron cross section in the library and its overall accuracy. In this paper lambda factors were computed using RMET21 from ENDF/B-VII.1 for nTRACER to investigate its dependence on temperature and background cross section and replaced with lambda factors from HELIOS multi-group library. The procedure used for determining the intermediate resonance parameter for the isotope under study is introduced in the next section. Oxygen being one of the primary nuclide in PWR fuel has been selected for intermediate resonance parameters calculation

Intermediate care: for better or worse? Process evaluation of an intermediate care model between a university hospital and a residential home

Directory of Open Access Journals (Sweden)

Janmaat Tonnie ACM

2005-05-01

Full Text Available Abstract Background Intermediate care was developed in order to bridge acute, primary and social care, primarily for elderly persons with complex care needs. Such bridging initiatives are intended to reduce hospital stays and improve continuity of care. Although many models assume positive effects, it is often ambiguous what the benefits are and whether they can be transferred to other settings. This is due to the heterogeneity of intermediate care models and the variety of collaborating partners that set up such models. Quantitative evaluation captures only a limited series of generic structure, process and outcome parameters. More detailed information is needed to assess the dynamics of intermediate care delivery, and to find ways to improve the quality of care. Against this background, the functioning of a low intensity early discharge model of intermediate care set up in a residential home for patients released from an Amsterdam university hospital has been evaluated. The aim of this study was to produce knowledge for management to improve quality of care, and to provide more generalisable insights into the accumulated impact of such a model. Methods A process evaluation was carried out using quantitative and qualitative methods. Registration forms and patient questionnaires were used to quantify the patient population in the model. Statistical analysis encompassed T-tests and chi-squared test to assess significance. Semi-structured interviews were conducted with 21 staff members representing all disciplines working with the model. Interviews were transcribed and analysed using both 'open' and 'framework' approaches. Results Despite high expectations, there were significant problems. A heterogeneous patient population, a relatively unqualified staff and cultural differences between both collaborating partners impeded implementation and had an impact on the functioning of the model. Conclusion We concluded that setting up a low intensity

The Advantages of a Course in Intermediate Typewriting.

Science.gov (United States)

Nebel, Joseph A.

1980-01-01

Suggests a one-semester intermediate typewriting course for students who have not attained a speed of 30-35 words per minute. It would emphasize remedial exercises as well as exercises on letters, memos, reports, invoices, and other business forms. The student would then enter advanced typewriting, business machines, and communications. (JOW)

Numerology, hydrogenic levels, and the ordering of excited states in one-electron atoms

Science.gov (United States)

Armstrong, Lloyd, Jr.

1982-03-01

We show that the observed ordering of Rydberg states of one-electron atoms can be understood by assuming that these states are basically hydrogenic in nature. Much of the confusion concerning this point is shown to arise from the failure to differentiate between hydrogenic ordering as the nuclear charge approaches infinity, and hydrogenic ordering for an effective charge of one. The origin of κ ordering of Rydberg levels suggested by Sternheimer is considered within this picture, and the predictions of κ ordering are compared with those obtained by assuming hydrogenic ordering.

A Simple Treatment of the Liquidity Trap for Intermediate Macroeconomics Courses

Science.gov (United States)

Buttet, Sebastien; Roy, Udayan

2014-01-01

Several leading undergraduate intermediate macroeconomics textbooks now include a simple reduced-form New Keynesian model of short-run dynamics (alongside the IS-LM model). Unfortunately, there is no accompanying description of how the zero lower bound on nominal interest rates affects the model. In this article, the authors show how the…

Thomson scattering on argon surfatron plasmas at intermediate pressures: Axial profiles of the electron temperature and electron density

International Nuclear Information System (INIS)

Palomares, J.M.; Iordanova, E.; Veldhuizen, E.M. van; Baede, L.; Gamero, A.; Sola, A.; Mullen, J.J.A.M. van der

2010-01-01

The axial profiles of the electron density n e and electron temperature T e of argon surfatron plasmas in the pressure range of 6-20 mbar and microwave power between 32 and 82 W have been determined using Thomson Scattering of laser irradiation at 532 nm. For the electron density and temperature we found values in the ranges 5 x 10 18 e 19 m -3 and 1.1 e e and T e down to 8% and 3%, respectively. It is found that n e decreases in the direction of the wave propagation with a slope that is nearly constant. The slope depends on the pressure but not on the power. Just as predicted by theories we see that increasing the power leads to longer plasma columns. However, the plasmas are shorter than what is predicted by theories based on the assumption that for the plasma-wave interaction electron-atom collisions are of minor importance (the so-called collisionless regime). The plasma vanishes long before the critical value of the electron density is reached. In contrast to what is predicted by the positive column model it is found that T e does not stay constant along the column, but monotonically increases with the distance from the microwave launcher. Increases of more than 50% over 30 cm were found.

Effects of water stress on photosynthetic electron transport, photophosphorylation, and metabolite levels of Xanthium strumarium mesophyll cells.

Science.gov (United States)

Sharkey, T D; Badger, M R

1982-12-01

Several component processes of photosynthesis were measured in osmotically stressed mesophyll cells of Xanthium strumarium L. The ribulose-1,5-bisphosphate regeneration capacity was reduced by water stress. Photophoshorylation was sensitive to water stress but photosynthetic electron transport was unaffected by water potentials down to-40 bar (-4 MPa). The concentrations of several intermediates of the photosynthetic carbon-reduction cycle remained relatively constant and did not indicate that ATP supply was limiting photosynthesis in the water-stressed cells.

Identification of the substrate radical intermediate derived from ethanolamine during catalysis by ethanolamine ammonia-lyase.

Science.gov (United States)

Bender, Güneş; Poyner, Russell R; Reed, George H

2008-10-28

Rapid-mix freeze-quench (RMFQ) methods and electron paramagnetic resonance (EPR) spectroscopy have been used to characterize the steady-state radical in the deamination of ethanolamine catalyzed by adenosylcobalamin (AdoCbl)-dependent ethanolamine ammonia-lyase (EAL). EPR spectra of the radical intermediates formed with the substrates, [1-13C]ethanolamine, [2-13C]ethanolamine, and unlabeled ethanolamine were acquired using RMFQ trapping methods from 10 ms to completion of the reaction. Resolved 13C hyperfine splitting in EPR spectra of samples prepared with [1-13C]ethanolamine and the absence of such splitting in spectra of samples prepared with [2-13C]ethanolamine show that the unpaired electron is localized on C1 (the carbinol carbon) of the substrate. The 13C splitting from C1 persists from 10 ms throughout the time course of substrate turnover, and there was no evidence of a detectable amount of a product like radical having unpaired spin on C2. These results correct an earlier assignment for this radical intermediate [Warncke, K., et al. (1999) J. Am. Chem. Soc. 121, 10522-10528]. The EPR signals of the substrate radical intermediate are altered by electron spin coupling to the other paramagnetic species, cob(II)alamin, in the active site. The dipole-dipole and exchange interactions as well as the 1-13C hyperfine splitting tensor were analyzed via spectral simulations. The sign of the isotropic exchange interaction indicates a weak ferromagnetic coupling of the two unpaired electrons. A Co2+-radical distance of 8.7 A was obtained from the magnitude of the dipole-dipole interaction. The orientation of the principal axes of the 13C hyperfine splitting tensor shows that the long axis of the spin-bearing p orbital on C1 of the substrate radical makes an angle of approximately 98 degrees with the unique axis of the d(z2) orbital of Co2+.

Effect of EMIC Wave Normal Angle Distribution on Relativistic Electron Scattering in Outer RB

Science.gov (United States)

Khazanov, G. V.; Gamayunov, K. V.

2007-01-01

We present the equatorial and bounce average pitch angle diffusion coefficients for scattering of relativistic electrons by the H+ mode of EMIC waves. Both the model (prescribed) and self consistent distributions over the wave normal angle are considered. The main results of our calculation can be summarized as follows: First, in comparison with field aligned waves, the intermediate and highly oblique waves reduce the pitch angle range subject to diffusion, and strongly suppress the scattering rate for low energy electrons (E less than 2 MeV). Second, for electron energies greater than 5 MeV, the |n| = 1 resonances operate only in a narrow region at large pitch-angles, and despite their greatest contribution in case of field aligned waves, cannot cause electron diffusion into the loss cone. For those energies, oblique waves at |n| greater than 1 resonances are more effective, extending the range of pitch angle diffusion down to the loss cone boundary, and increasing diffusion at small pitch angles by orders of magnitude.

Introductory Overview of Intermediate-luminosity X-ray Objects

Science.gov (United States)

Colbert, E. J. M.

2001-05-01

Intermediate-luminosity X-ray Objects (IXOs) are defined as compact objects having X-ray luminosities between those of X-ray binaries and low-luminosity AGNs (i.e., 1039.0 erg s-1 < ~ LX [IXOs] < ~ 1041.0 erg s-1). It is not currently known if these objects are intermediate-mass (M ~ 102-104 Msun) black holes accreting near the Eddington limit, near-solar-mass black holes in a super-Eddington state, or are, in some cases, just supermassive black holes accreting at very low rates. However, the first idea has been popularized by recent press coverage. IXOs are quite common (present in about half of spiral galaxies) and are typically found displaced from the optical nucleus, reducing the likelihood that they are low-luminosity AGN. Nearly all of our knowledge of these objects comes from X-ray observations, as observations of optical, NIR and radio counterparts are not widely known. In this session, we will address (1) the phenomenology of the objects, (2) possible geometry and accretion mechanisms for these objects (i.e., are they more similar to black hole X-ray binaries or AGNs), (3) the central black hole masses, and (4) the formation mechanism for these black holes, if they are of intermediate mass. In this talk, I will focus primarily on giving background information of these fascinating objects.

The impact of intermediate care services on job satisfaction, skills and career development opportunities.

Science.gov (United States)

Nancarrow, Susan

2007-07-01

The purpose of this study was to examine, in depth, the impact of intermediate care services on staff job satisfaction, skills development and career development opportunities. Recruitment and retention difficulties present a major barrier to the effective delivery of intermediate care services in the UK. The limited existing literature is contradictory, but points to the possibility of staff deskilling and suggests that intermediate care is poorly understood and may be seen by other practitioners as being of lower status than hospital work. These factors have the potential to reduce staff morale and limit the possibilities of recruiting staff. The research is based on interviews with 26 staff from case studies of two intermediate care services in South Yorkshire. Participants reported high levels of job satisfaction, which was because of the enabling philosophy of care, increased autonomy, the setting of care and the actual teams within which the workers were employed. For most disciplines, intermediate care facilitated the application of existing skills in a different way; enhancing some skills, while restricting the use of others. Barriers to career development opportunities were attributed to the relative recency of intermediate care services, small size of the services and lack of clear career structures. Career development opportunities in intermediate care could be improved through staff rotations through acute, community and intermediate care to increase their awareness of the roles of intermediate care staff. The non-hierarchical management structures limits management career development opportunities, instead, there is a need to enhance professional growth opportunities through the use of consultant posts and specialization within intermediate care. This study provides insight into the impact of an increasingly popular model of care on the roles and job satisfaction of workers and highlights the importance of this learning for recruitment and retention of

Oxoferryl-Porphyrin Radical Catalytic Intermediate in Cytochrome bd Oxidases Protects Cells from Formation of Reactive Oxygen Species*

Science.gov (United States)

Paulus, Angela; Rossius, Sebastiaan Gijsbertus Hendrik; Dijk, Madelon; de Vries, Simon

2012-01-01

The quinol-linked cytochrome bd oxidases are terminal oxidases in respiration. These oxidases harbor a low spin heme b558 that donates electrons to a binuclear heme b595/heme d center. The reaction with O2 and subsequent catalytic steps of the Escherichia coli cytochrome bd-I oxidase were investigated by means of ultra-fast freeze-quench trapping followed by EPR and UV-visible spectroscopy. After the initial binding of O2, the O–O bond is heterolytically cleaved to yield a kinetically competent heme d oxoferryl porphyrin π-cation radical intermediate (compound I) magnetically interacting with heme b595. Compound I accumulates to 0.75–0.85 per enzyme in agreement with its much higher rate of formation (∼20,000 s−1) compared with its rate of decay (∼1,900 s−1). Compound I is next converted to a short lived heme d oxoferryl intermediate (compound II) in a phase kinetically matched to the oxidation of heme b558 before completion of the reaction. The results indicate that cytochrome bd oxidases like the heme-copper oxidases break the O–O bond in a single four-electron transfer without a peroxide intermediate. However, in cytochrome bd oxidases, the fourth electron is donated by the porphyrin moiety rather than by a nearby amino acid. The production of reactive oxygen species by the cytochrome bd oxidase was below the detection level of 1 per 1000 turnovers. We propose that the two classes of terminal oxidases have mechanistically converged to enzymes in which the O–O bond is broken in a single four-electron transfer reaction to safeguard the cell from the formation of reactive oxygen species. PMID:22287551

An Analysis of the Regulatory Environment Governing Hearsay Electronic Evidence in South Africa: Suggestions for Reform – Part One

Directory of Open Access Journals (Sweden)

Lee Swales

2018-03-01

Full Text Available The purpose of this two-part article is to examine the regulatory environment governing hearsay electronic evidence in South Africa – with a view to providing clear, practical suggestions for regulatory reform in the context of the South African Law Reform Commission's most recent Discussion Paper on electronic evidence. Technology has become an indispensable part of modern life. In particular, the Internet has facilitated new forms of business enterprise, and shifted basic communication norms. From a legal perspective, technology has presented several novel challenges for courts and legal practitioners to deal with – one of these key challenges relates to electronic evidence and in particular the application of the hearsay rules to the digital environment. The South African Law Reform Commission has identified the application of the hearsay rule as one of the core concerns with regard to electronic evidence, and certain academic analysis has revealed inefficiency in the current legal position which may involve multiple sources of law. Moreover, the Law Society of South Africa has stated that there is some confusion amongst members of the profession in relation to hearsay as it applies to electronic evidence. With the pervasive and burgeoning nature of technology, and with the Internet in mind, it is natural to assume that electronic evidence will be relevant in most forms of legal proceedings in future, and hearsay electronic evidence in particular will play an increasingly important role in years to come. Consequently, part one of this article will consider the key definitional concept in relation to electronic evidence – data messages - and examine whether the definition should be revised. In addition, part one of this article will answer two further critical questions posed by the South African Law Reform Commission in relation to data messages and hearsay evidence, namely: should a data message constitute hearsay? And, how should one

Pulse radiolytic one-electron reduction of 2-hydroxy- and 2,6-dihydroxy-9,10-anthraquinones

International Nuclear Information System (INIS)

Pal, Haridas; Mukherjee, Tulsi; Mittal, J.P.

1994-01-01

The semiquinone free radicals produced by one-electron reduction of 2-hydroxy-9-10-anthraquinone (2HAQ) and 2,6-dihydroxy-9,10-anthraquinone (26DHAQ) in aqueous formate solution, water-isopropyl alcohol-acetone mixed solvent and isopropyl alcohol have been studied using the pulse radiolysis technique. The absorption characteristics, kinetic parameters of formation and decay, acid-base behaviour and redox characteristics of the semiquinones have been investigated and compared with the corresponding characteristics of a few intramolecularly hydro-bonded anthrasemiquinone derivatives. The non-hydrogen-bonded semiquinones show two pKsub(a) values (4.7 and 10.7 for 2HAQ and 5.4 and 8.7 for 26DHAQ, respectively) within the pH range 1-14, whereas other intramolecularly hydrogen-bonded semiquinones show only one pKsub(a). The one-electron reduction potential (E' 7 ) values for 2HAQ (-440 mV) and 26DHAQ (- 400 mV) are more negative than those of the intramolecularly hydrogen-bonded systems. (Author)

The intermediate state in Patd

African Journals Online (AJOL)

) Jesus had assumed. (concerning the 'intermediate state') as existing, anything which does not exist. Three basic things about the intermediate state emerge from the parable: (a) Jesus recognizes that at the moment of death, in ipso articulo.

One-electron reduction of 1,2-dihydroxy-9,10-anthraquinone and some of its transition metal complexes in aqueous solution and in aqueous isopropanol-acetone-mixed solvent: a steady-state and pulse radiolysis study

International Nuclear Information System (INIS)

Das, S.; Bhattacharya, A.; Mandal, P.C.; Rath, M.C.; Mukherjee, T.

2002-01-01

One-electron reduction of 1,2-dihydroxy-9,10-anthraquinone (DHA) and its complexes with Cu(II), Ni(II) and Fe(III), by acetone ketyl radical, (CH 3 ) 2 C·OH, was carried out in aqueous solution and in aqueous isopropanol acetone mixed solvent using both steady-state gamma radiolysis and pulse radiolysis techniques. The rate constants for the reduction of DHA at different pH values by the ketyl radical are in the order of ∼10 9 dm 3 mol -1 s -1 , whereas those for the metal complexes are comparatively less. These rate constants are, however, in conformity with the one-electron reduction potentials of the ligand in free DHA and in its metal complexes. Decay kinetics of the one-electron reduced semiquinones of the free ligand and its metal complexes suggest disproportionation of the semiquinone in the case of the free ligand and intermolecular electron transfer from the co-ordinated semiquinone radical to the metal centre in the case of the metal complexes

Investigation of organometallic reaction mechanisms with one and two dimensional vibrational spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Cahoon, James Francis [Univ. of California, Berkeley, CA (United States)

2008-12-01

One and two dimensional time-resolved vibrational spectroscopy has been used to investigate the elementary reactions of several prototypical organometallic complexes in room temperature solution. The electron transfer and ligand substitution reactions of photogenerated 17-electron organometallic radicals CpW(CO)₃ and CpFe(CO)₂ have been examined with one dimensional spectroscopy on the picosecond through microsecond time-scales, revealing the importance of caging effects and odd-electron intermediates in these reactions. Similarly, an investigation of the photophysics of the simple Fischer carbene complex Cr(CO)₅[CMe(OMe)] showed that this class of molecule undergoes an unusual molecular rearrangement on the picosecond time-scale, briefly forming a metal-ketene complex. Although time-resolved spectroscopy has long been used for these types of photoinitiated reactions, the advent of two dimensional vibrational spectroscopy (2D-IR) opens the possibility to examine the ultrafast dynamics of molecules under thermal equilibrium conditions. Using this method, the picosecond fluxional rearrangements of the model metal carbonyl Fe(CO)₅ have been examined, revealing the mechanism, time-scale, and transition state of the fluxional reaction. The success of this experiment demonstrates that 2D-IR is a powerful technique to examine the thermally-driven, ultrafast rearrangements of organometallic molecules in solution.

Vertical one-dimensional electron cyclotron emission imaging diagnostic for HT-7 tokamak

International Nuclear Information System (INIS)

Wang Jun; Xu Xiaoyuan; Wen Yizhi; Yu Changxuan; Wan Baonian; Luhmann, N.C.; Wang, Jian; Xia, Z.G.

2005-01-01

A vertical resolved 16-channel electron cyclotron emission imaging (ECEI) diagnostic has been developed and installed on the HT7 Tokamak for measuring plasma electron cyclotron emission with a temporal resolution of 0.5 us. The system is working on a fixed frequency 97.5 GHz in the first stage. The sample volumes of the system are aligned vertically with a vertical channel spacing of 11 mm, and can be shifted across the plasma cross-section by varying the toroidal magnetic field. The high spatial resolution of the system is achieved by utilizing a low cost linear mixer/receiver array and an optical imaging system. The focus location may be shifted horizontally via translation of one of the optical imaging elements. The detail of the system design and laboratory testing of the ECE Imaging optics are presented, together with HT7 plasma data. (author)

Improved core electron confinement on JET

International Nuclear Information System (INIS)

Litaudon, X.; Baranov, Y.; Voitsekhovitch, I.

1999-01-01

Formation of core regions with reduced electron transport is reported in regimes with current profile shaping at JET. The electron heat diffusivity (Χ c ) is reduced down to 0.5 m 2 /s in the region of low magnetic shear with an ICRH power of 1 MW with no indication of a threshold. In the high performance optimised shear regime, obtained in scenarios dominated by ion heating, internal transport barriers on the ion temperature profiles are simultaneously accompanied by a significant reduction of the electron heat diffusivity at two-third of the plasma radius. In this regime, recent results and measurements obtained with the new gas-box divertor configuration are reported together with their transport analyses. The results indicate that Χ c is reduced by one order of magnitude in a spatially localised region. (authors)

Electron scattering and reactions from exotic nuclei

International Nuclear Information System (INIS)

Karataglidis, S.

2017-01-01

The SCRIT and FAIR/ELISe experiments are the first to attempt to measure directly electron scattering form factors from nuclei far from stability. This will give direct information for the (one-body) charge densities of those systems, about which there is little information available. The SCRIT experiment will be taking data for medium-mass exotic nuclei, while the electron-ion collider at ELISe, when constructed, will be able to measure form factors for a wide range of exotic nuclei, as available from the radioactive ion beams produced by the FAIR experiment. Other facilities are now being proposed, which will also consider electron scattering from exotic nuclei at higher energies, to study short-range correlations in exclusive reactions. This review will consider all available information concerning the current status (largely theoretical) of electron scattering from exotic nuclei and, where possible, complement such information with equivalent information concerning the neutron densities of those exotic systems, as obtained from intermediate energy proton scattering. The issue of long- and short-range correlations will be discussed, and whether extending such studies to the exotic sector will elicit new information. (orig.)

Electron scattering and reactions from exotic nuclei

Energy Technology Data Exchange (ETDEWEB)

Karataglidis, S. [University of Johannesburg, Department of Physics, Auckland Park (South Africa); University of Melbourne, School of Physics, Victoria (Australia)

2017-04-15

The SCRIT and FAIR/ELISe experiments are the first to attempt to measure directly electron scattering form factors from nuclei far from stability. This will give direct information for the (one-body) charge densities of those systems, about which there is little information available. The SCRIT experiment will be taking data for medium-mass exotic nuclei, while the electron-ion collider at ELISe, when constructed, will be able to measure form factors for a wide range of exotic nuclei, as available from the radioactive ion beams produced by the FAIR experiment. Other facilities are now being proposed, which will also consider electron scattering from exotic nuclei at higher energies, to study short-range correlations in exclusive reactions. This review will consider all available information concerning the current status (largely theoretical) of electron scattering from exotic nuclei and, where possible, complement such information with equivalent information concerning the neutron densities of those exotic systems, as obtained from intermediate energy proton scattering. The issue of long- and short-range correlations will be discussed, and whether extending such studies to the exotic sector will elicit new information. (orig.)

A Reduced Order, One Dimensional Model of Joint Response

Energy Technology Data Exchange (ETDEWEB)

DOHNER,JEFFREY L.

2000-11-06

As a joint is loaded, the tangent stiffness of the joint reduces due to slip at interfaces. This stiffness reduction continues until the direction of the applied load is reversed or the total interface slips. Total interface slippage in joints is called macro-slip. For joints not undergoing macro-slip, when load reversal occurs the tangent stiffness immediately rebounds to its maximum value. This occurs due to stiction effects at the interface. Thus, for periodic loads, a softening and rebound hardening cycle is produced which defines a hysteretic, energy absorbing trajectory. For many jointed sub-structures, this hysteretic trajectory can be approximated using simple polynomial representations. This allows for complex joint substructures to be represented using simple non-linear models. In this paper a simple one dimensional model is discussed.

Growth of Thermophilic and Hyperthermophilic Fe(III)-Reducing Microorganisms on a Ferruginous Smectite as the Sole Electron Acceptor▿

Science.gov (United States)

Kashefi, Kazem; Shelobolina, Evgenya S.; Elliott, W. Crawford; Lovley, Derek R.

2008-01-01

Recent studies have suggested that the structural Fe(III) within phyllosilicate minerals, including smectite and illite, is an important electron acceptor for Fe(III)-reducing microorganisms in sedimentary environments at moderate temperatures. The reduction of structural Fe(III) by thermophiles, however, has not previously been described. A wide range of thermophilic and hyperthermophilic Archaea and Bacteria from marine and freshwater environments that are known to reduce poorly crystalline Fe(III) oxides were tested for their ability to reduce structural (octahedrally coordinated) Fe(III) in smectite (SWa-1) as the sole electron acceptor. Two out of the 10 organisms tested, Geoglobus ahangari and Geothermobacterium ferrireducens, were not able to conserve energy to support growth by reduction of Fe(III) in SWa-1 despite the fact that both organisms were originally isolated with solid-phase Fe(III) as the electron acceptor. The other organisms tested were able to grow on SWa-1 and reduced 6.3 to 15.1% of the Fe(III). This is 20 to 50% less than the reported amounts of Fe(III) reduced in the same smectite (SWa-1) by mesophilic Fe(III) reducers. Two organisms, Geothermobacter ehrlichii and archaeal strain 140, produced copious amounts of an exopolysaccharide material, which may have played an active role in the dissolution of the structural iron in SWa-1 smectite. The reduction of structural Fe(III) in SWa-1 by archaeal strain 140 was studied in detail. Microbial Fe(III) reduction was accompanied by an increase in interlayer and octahedral charges and some incorporation of potassium and magnesium into the smectite structure. However, these changes in the major element chemistry of SWa-1 smectite did not result in the formation of an illite-like structure, as reported for a mesophilic Fe(III) reducer. These results suggest that thermophilic Fe(III)-reducing organisms differ in their ability to reduce and solubilize structural Fe(III) in SWa-1 smectite and that SWa-1

Digital intermediate frequency QAM modulator using parallel processing

Science.gov (United States)

Pao, Hsueh-Yuan [Livermore, CA; Tran, Binh-Nien [San Ramon, CA

2008-05-27

The digital Intermediate Frequency (IF) modulator applies to various modulation types and offers a simple and low cost method to implement a high-speed digital IF modulator using field programmable gate arrays (FPGAs). The architecture eliminates multipliers and sequential processing by storing the pre-computed modulated cosine and sine carriers in ROM look-up-tables (LUTs). The high-speed input data stream is parallel processed using the corresponding LUTs, which reduces the main processing speed, allowing the use of low cost FPGAs.

The new frontiers of electron scattering at intermediate energy

International Nuclear Information System (INIS)

Frois, B.

1984-08-01

Recent advances in experimental techniques have produced a new generation of electron scattering data. This paper explores the frontiers of this field and shows how our prospects for the future may be modified. Nuclear structure has been determined with an unprecedented accuracy defining clearly the limits of the most advanced theoretical descriptions. Large meson exchange currents are measured quantitatively with precision. Recent data on the electrodisintegration of deuterium at threshold and on the magnetic form factor of 3 He and tritium show that the pionic exchange current is well understood. There is no satisfactory theoretical description of shorter range processes

Total electron scattering cross sections for methanol and ethanol at intermediate energies

International Nuclear Information System (INIS)

Silva, D G M; Tejo, T; Lopes, M C A; Muse, J; Romero, D; Khakoo, M A

2010-01-01

Absolute total cross section (TCS) measurements of electron scattering from gaseous methanol and ethanol molecules are reported for impact energies from 60 to 500 eV, using the linear transmission method. The attenuation of intensity of a collimated electron beam through the target volume is used to determine the absolute TCS for a given impact energy, using the Beer-Lambert law to first approximation. Besides these experimental measurements, we have also determined TCS using the additivity rule.

[Therapy of intermediate uveitis].

Science.gov (United States)

Doycheva, D; Deuter, C; Zierhut, M

2014-12-01

Intermediate uveitis is a form of intraocular inflammation in which the vitreous body is the major site of inflammation. Intermediate uveitis is primarily treated medicinally and systemic corticosteroids are the mainstay of therapy. When recurrence of uveitis or side effects occur during corticosteroid therapy an immunosuppressive treatment is required. Cyclosporine A is the only immunosuppressive agent that is approved for therapy of uveitis in Germany; however, other immunosuppressive drugs have also been shown to be effective and well-tolerated in patients with intermediate uveitis. In severe therapy-refractory cases when conventional immunosuppressive therapy has failed, biologics can be used. In patients with unilateral uveitis or when the systemic therapy is contraindicated because of side effects, an intravitreal steroid treatment can be carried out. In certain cases a vitrectomy may be used.

One-Electron Standard Reduction Potentials of Nitroaromatic and Cyclic Nitramine Explosives

Science.gov (United States)

2010-01-01

the preparation of solutions. Glassware and plasticware was rinsed with acetone and distilled water prior to soaking overnight in a 5.0 M nitric acid ...prior contact with metal ions was soaked in a 5.0 mM oxalic acid bath overnight before following the above procedure. 40-Nitroacetophenone, 1,3...observable (Colon et al., 2006b) nitrosobenzene and N-hydroxylaniline intermediates to form the final stable product aniline (Fig. 1a). However, NACs

Theoretical optoelectronic analysis of intermediate-band photovoltaic material based on ZnY1−xOx (Y = S, Se, Te) semiconductors by first-principles calculations

International Nuclear Information System (INIS)

Wu Kong-Ping; Zhou Meng-Ran; Huang You-Rui; Gu Shu-Lin; Ye Jian-Dong; Zhu Shun-Ming; Zhang Rong; Zheng You-Dou; Tang Kun

2013-01-01

The structural, energetic, and electronic properties of lattice highly mismatched ZnY 1−x O x (Y = S, Se, Te) ternary alloys with dilute O concentrations are calculated from first principles within the density functional theory. We demonstrate the formation of an isolated intermediate electronic band structure through diluted O-substitute in zinc-blende ZnY (Y = S, Se, Te) at octahedral sites in a semiconductor by the calculations of density of states (DOS), leading to a significant absorption below the band gap of the parent semiconductor and an enhancement of the optical absorption in the whole energy range of the solar spectrum. It is found that the intermediate band states should be described as a result of the coupling between impurity O 2p states with the conduction band states. Moreover, the intermediate bands (IBs) in ZnTeO show high stabilization with the change of O concentration resulting from the largest electronegativity difference between O and Te compared with in the other ZnSO and ZnSeO. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Dynamic Architecture of Eukaryotic DNA Replication Forks In Vivo, Visualized by Electron Microscopy.

Science.gov (United States)

Zellweger, Ralph; Lopes, Massimo

2018-01-01

The DNA replication process can be heavily perturbed by several different conditions of genotoxic stress, particularly relevant for cancer onset and therapy. The combination of psoralen crosslinking and electron microscopy has proven instrumental to reveal the fine architecture of in vivo DNA replication intermediates and to uncover their remodeling upon specific conditions of genotoxic stress. The replication structures are stabilized in vivo (by psoralen crosslinking) prior to extraction and enrichment procedures, allowing their visualization at the transmission electron microscope. This chapter outlines the procedures required to visualize and interpret in vivo replication intermediates of eukaryotic genomic DNA, and includes an improved method for enrichment of replication intermediates, compared to previously used BND-cellulose columns.

Design of intermediate die shape of multistage profile drawing for linear motion guide

International Nuclear Information System (INIS)

Lee, Sang Kon; Lee, Jae Eun; Kim, Sung Min; Kim, Byung Min

2010-01-01

The design of an intermediate die shape is very important in multistage profile drawing. In this study, two design methods for the intermediate die shape of a multistage profile drawing for producing a linear motion guide (LM) guide is proposed. One is the electric field analysis method using the equipotential lines generated by electric field analysis, and the other is the virtual die method using a virtual drawing die constructed from the initial material and the final product shape. In order to design the intermediate die shapes of a multistage profile drawing for producing LM guide, the proposed design methods are applied, and then FE analysis and profile drawing experiment are performed. As a result, based on the measurement of dimensional accuracy, it can be known that the intermediate die shape can be designed effectively

One-electron densities of freely rotating Wigner molecules

Science.gov (United States)

Cioslowski, Jerzy

2017-12-01

A formalism enabling computation of the one-particle density of a freely rotating assembly of identical particles that vibrate about their equilibrium positions with amplitudes much smaller than their average distances is presented. It produces densities as finite sums of products of angular and radial functions, the length of the expansion being determined by the interplay between the point-group and permutational symmetries of the system in question. Obtaining from a convolution of the rotational and bosonic components of the parent wavefunction, the angular functions are state-dependent. On the other hand, the radial functions are Gaussians with maxima located at the equilibrium lengths of the position vectors of individual particles and exponents depending on the scalar products of these vectors and the eigenvectors of the corresponding Hessian as well as the respective eigenvalues. Although the new formalism is particularly useful for studies of the Wigner molecules formed by electrons subject to weak confining potentials, it is readily adaptable to species (such as ´balliums’ and Coulomb crystals) composed of identical particles with arbitrary spin statistics and permutational symmetry. Several examples of applications of the present approach to the harmonium atoms within the strong-correlation regime are given.

High-performance polyimide nanocomposites with core-shell AgNWs@BN for electronic packagings

Energy Technology Data Exchange (ETDEWEB)

Zhou, Yongcun; Liu, Feng, E-mail: liufeng@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an Shaanxi 710072 (China)

2016-08-22

The increasing density of electronic devices underscores the need for efficient thermal management. Silver nanowires (AgNWs), as one-dimensional nanostructures, possess a high aspect ratio and intrinsic thermal conductivity. However, high electrical conductivity of AgNWs limits their application for electronic packaging. We synthesized boron nitride-coated silver nanowires (AgNWs@BN) using a flexible and fast method followed by incorporation into synthetic polyimide (PI) for enhanced thermal conductivity and dielectric properties of nanocomposites. The thinner boron nitride intermediate nanolayer on AgNWs not only alleviated the mismatch between AgNWs and PI but also enhanced their interfacial interaction. Hence, the maximum thermal conductivity of an AgNWs@BN/PI composite with a filler loading up to 20% volume was increased to 4.33 W/m K, which is an enhancement by nearly 23.3 times compared with that of the PI matrix. The relative permittivity and dielectric loss were about 9.89 and 0.015 at 1 MHz, respectively. Compared with AgNWs@SiO{sub 2}/PI and Ag@BN/PI composites, boron nitride-coated core-shell structures effectively increased the thermal conductivity and reduced the permittivity of nanocomposites. The relative mechanism was studied and discussed. This study enables the identification of appropriate modifier fillers for polymer matrix nanocomposites.

Isochoric heating of reduced mass targets by ultra-intense laser produced relativistic electrons

Energy Technology Data Exchange (ETDEWEB)

Neumayer, P; Lee, H J; Offerman, D; Shipton, E; Kemp, A; Kritcher, A L; Doppner, T; Back, C A; Glenzer, S H

2009-02-04

We present measurements of the chlorine K-alpha emission from reduced mass targets, irradiated with ultra-high intensity laser pulses. Chlorinated plastic targets with diameters down to 50 micrometers and mass of a few 10{sup -8} g were irradiated with up to 7 J of laser energy focused to intensities of several 10{sup 19} W/cm{sup 2}. The conversion of laser energy to K-alpha radiation is measured, as well as high resolution spectra that allow observation of line shifts, indicating isochoric heating of the target up to 18 eV. A zero-dimensional 2-temperature equilibration model, combined with electron impact K-shell ionization and post processed spectra from collisional radiative calculations reproduces the observed K-alpha yields and line shifts, and shows the importance of target expansion due to the hot electron pressure.

Measurement of mass distribution of U-235 fission products in the intermediate neutron region

International Nuclear Information System (INIS)

Nakagomi, Yoshihiro; Kobayashi, Shohei; Yamamoto, Shuji; Kanno, Ikuo; Wakabayashi, Hiroaki.

1982-01-01

The mass distribution and the momentum distribution of U-235 fission products in the intermediate neutron region were measured by using a combination system of the Yayoi intermediate neutron column and an electron linear accelerator. The double energy measurement method was applied. A fission chamber, which consists of an enriched uranium target and two Si surface barrier detectors, was used for the measurement of the neutrons with energy above 1.3 eV. The linear accelerator was operated at the repetition rate of 100 Hz and the pulse width of 10 ns. The data obtained by the two-dimensional pulse height analysis were analyzed by the Schmitt's method. The preliminary results of the mass distribution and the momentum distribution of fission fragments were obtained. (Kato, T.)

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.

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.

Modelling interaction cross sections for intermediate and low energy ions

International Nuclear Information System (INIS)

Toburen, L.H.; Shinpaugh, J.L.; Justiniano, E.L.B.

2002-01-01

When charged particles slow in tissue they undergo electron capture and loss processes than can have profound effects on subsequent interaction cross sections. Although a large amount of data exists for the interaction of bare charged particles with atoms and molecules, few experiments have been reported for these 'dressed' particles. Projectile electrons contribute to an impact-parameter-dependent screening of the projectile charge that precludes straightforward scaling of energy loss cross sections from those of bare charged particles. The objective of this work is to develop an analytical model for the energy-loss-dependent effects of screening on differential ionisation cross sections that can be used in track structure calculations for high LET ions. As a first step a model of differential ionisation cross sections for bare ions has been combined with a simple screening model to explore cross sections for intermediate and low energy dressed ions in collisions with atomic and molecular gas targets. The model is described briefly and preliminary results compared to measured electron energy spectra. (author)

One-electron reduction reactions with enzymes in solution

International Nuclear Information System (INIS)

Bisby, R.H.; Cundall, R.B.; Redpath, J.L.; Adams, G.E.

1976-01-01

At pH 8 and above, hydrated electrons react with ribonuclease lysozyme and α-chymotrypsin to form transient products whose spectra resemble, but are not identical to, those for the RSSR - radical anion already known for simple disulphides. Assuming a value for the extinction coefficient similar to that for RSSR - in simple disulphides, only a fraction of the hydrated electrons are shown to react with the disulphide bridges: the remainder react at other sites in the protein molecule, such as histidine, tyrosine and, in lysozyme, tryptophan residues, giving rise to comparatively weak optical absorptions between 300 and 400 nm. This has been substantiated by studying the reaction of e - sub(aq) with subtilisin Novo (an enzyme which does not contain disulphide bridges), with enzymes in which the sulphur bridges have been oxidised and with some amino acid derivatives. On lowering the pH of the solution the intensity of the RSSR - absorption diminishes as the protonated histidine residues become the favoured reaction sites. In acid solutions (pH 2 to 3) the transient optical absoptions observed are due to reactions of hydrogen atoms with the aromatic amino acids tyrosine, tryptophan and phenylalanine. The CO - 2 radical anion is only observed to transfer an electron to disulphide groups in ribonuclease, although the effect of repeated pulsing shows that some reaction must occur elsewhere in the protein molecule. In acid solutions, protonation of the electron adduct appears to produce the RSSRH. radical, whose spectrum has a maximum at 340 nm. (author)

Electronic laboratory system reduces errors in National Tuberculosis Program: a cluster randomized controlled trial.

Science.gov (United States)

Blaya, J A; Shin, S S; Yale, G; Suarez, C; Asencios, L; Contreras, C; Rodriguez, P; Kim, J; Cegielski, P; Fraser, H S F

2010-08-01

To evaluate the impact of the e-Chasqui laboratory information system in reducing reporting errors compared to the current paper system. Cluster randomized controlled trial in 76 health centers (HCs) between 2004 and 2008. Baseline data were collected every 4 months for 12 months. HCs were then randomly assigned to intervention (e-Chasqui) or control (paper). Further data were collected for the same months the following year. Comparisons were made between intervention and control HCs, and before and after the intervention. Intervention HCs had respectively 82% and 87% fewer errors in reporting results for drug susceptibility tests (2.1% vs. 11.9%, P = 0.001, OR 0.17, 95%CI 0.09-0.31) and cultures (2.0% vs. 15.1%, P Chasqui users sent on average three electronic error reports per week to the laboratories. e-Chasqui reduced the number of missing laboratory results at point-of-care health centers. Clinical users confirmed viewing electronic results not available on paper. Reporting errors to the laboratory using e-Chasqui promoted continuous quality improvement. The e-Chasqui laboratory information system is an important part of laboratory infrastructure improvements to support multidrug-resistant tuberculosis care in Peru.

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 ...

One- or two-electron water oxidation, hydroxyl radical, or H_2O_2 evolution

International Nuclear Information System (INIS)

Siahrostami, Samira; Li, Guo-Ling; Viswanathan, Venkatasubramanian; Nørskov, Jens K.

2017-01-01

Electrochemical or photoelectrochemcial oxidation of water to form hydrogen peroxide (H_2O_2) or hydroxyl radicals (•OH) offers a very attractive route to water disinfection, and the first process could be the basis for a clean way to produce hydrogen peroxide. A major obstacle in the development of effective catalysts for these reactions is that the electrocatalyst must suppress the thermodynamically favored four-electron pathway leading to O_2 evolution. Here, we develop a thermochemical picture of the catalyst properties that determine selectivity toward the one, two, and four electron processes leading to •OH, H_2O_2, and O_2.

The optimum intermediate pressure of two-stages vapor compression refrigeration cycle for Air-Conditioning unit

Science.gov (United States)

Ambarita, H.; Sihombing, H. V.

2018-03-01

Vapor compression cycle is mainly employed as a refrigeration cycle in the Air-Conditioning (AC) unit. In order to save energy, the Coefficient of Performance (COP) of the need to be improved. One of the potential solutions is to modify the system into multi-stages vapor compression cycle. The suitable intermediate pressure between the high and low pressures is one of the design issues. The present work deals with the investigation of an optimum intermediate pressure of two-stages vapor compression refrigeration cycle. Typical vapor compression cycle that is used in AC unit is taken into consideration. The used refrigerants are R134a. The governing equations have been developed for the systems. An inhouse program has been developed to solve the problem. COP, mass flow rate of the refrigerant and compressor power as a function of intermediate pressure are plotted. It was shown that there exists an optimum intermediate pressure for maximum COP. For refrigerant R134a, the proposed correlations need to be revised.

Calculation of fluctuations and photoemission properties in a tetrahedral-cluster model for an intermediate-valence system

International Nuclear Information System (INIS)

Reich, A.; Falicov, L.M.

1986-01-01

An exact solution of a four-site tetrahedral-crystal model, the smallest face-centered-cubic crystal, is presented in the case of an intermediate-valence system. The model consists of the following: (a) one extended orbital and one localized orbital per atom, (b) an interatomic transfer term between extended orbitals, (c) an interatomic hybridization between the localized and extended orbitals, (d) strong intra-atomic Coulomb repulsion between opposite-spin localized states, and (e) intermediate-strength intra-atomic Coulomb repulsion between the localized and extended states. These competing effects are examined as they manifest themselves in the intermediate-valence, photoemission, inverse-photoemission, and thermodynamic properties

Electronic Interactions of n-Doped Perylene Diimide Groups Appended to Polynorbornene Chains: Implications for Electron Transport in Organic Electronics.

Science.gov (United States)

Nguyen, Minh T; Biberdorf, Joshua D; Holliday, Bradley J; Jones, Richard A

2017-11-01

A polymer consisting of a polynorbornene backbone with perylene diimide (PDI) pendant groups on each monomeric unit is synthesized via ring opening metathesis polymerization. The PDI pendant groups along the polymer backbone, studied by UV-vis absorption, fluorescence emission, and electron paramagnetic resonance spectroscopy in addition to electrochemical methods, show evidence of molecular aggregation and corresponding electronic coupling with neighboring groups, which forms pathways for efficient electron transport from one group to another in a specific reduced form. When n-doped, the title polymer shows redox conductivity of 5.4 × 10 -3 S cm -1 , comparable with crystalline PDI materials, and is therefore a promising material for use in organic electronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Intermediate Hosts on Emerging Zoonoses.

Science.gov (United States)

Cui, Jing-An; Chen, Fangyuan; Fan, Shengjie

2017-08-01

Most emerging zoonotic pathogens originate from animals. They can directly infect humans through natural reservoirs or indirectly through intermediate hosts. As a bridge, an intermediate host plays different roles in the transmission of zoonotic pathogens. In this study, we present three types of pathogen transmission to evaluate the effect of intermediate hosts on emerging zoonotic diseases in human epidemics. These types are identified as follows: TYPE 1, pathogen transmission without an intermediate host for comparison; TYPE 2, pathogen transmission with an intermediate host as an amplifier; and TYPE 3, pathogen transmission with an intermediate host as a vessel for genetic variation. In addition, we established three mathematical models to elucidate the mechanisms underlying zoonotic disease transmission according to these three types. Stability analysis indicated that the existence of intermediate hosts increased the difficulty of controlling zoonotic diseases because of more difficult conditions to satisfy for the disease to die out. The human epidemic would die out under the following conditions: TYPE 1: [Formula: see text] and [Formula: see text]; TYPE 2: [Formula: see text], [Formula: see text], and [Formula: see text]; and TYPE 3: [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] Simulation with similar parameters demonstrated that intermediate hosts could change the peak time and number of infected humans during a human epidemic; intermediate hosts also exerted different effects on controlling the prevalence of a human epidemic with natural reservoirs in different periods, which is important in addressing problems in public health. Monitoring and controlling the number of natural reservoirs and intermediate hosts at the right time would successfully manage and prevent the prevalence of emerging zoonoses in humans.

One watt initiative: A global effort to reduce leaking electricity

International Nuclear Information System (INIS)

Meier, Alan K.; LeBot, Benoit

1999-01-01

Many domestic appliances and commercial equipment consume some electric power when they are switched off or not performing their primary purpose. The typical loss per appliance is low (from 1 to 25 W) but, when multiplied by the billions of appliances in houses and in commercial buildings, standby losses represent a significant fraction of total electricity use. Several initiatives to reduce standby losses have appeared in different parts of the world. One proposal, the 1-watt plan, seeks to harmonize these initiatives by establishing a single target for all appliances. This paper explains the background to the 1-watt plan, identifies some unresolved aspects, and gives some estimates of energy savings

Localized second-order optical potential for electron scattering in terms of imaginary-frequency susceptibilities

International Nuclear Information System (INIS)

Valone, S.M.; Truhlar, D.G.; Thirumialai, D.

1982-01-01

A local approximation to the second-order optical potential for elastic scattering of low-energy electrons from ground-state atoms is expressed in terms of the imaginary-frequency susceptibilities of the atom due to a point charge and to modified perturbing potentials. This provides a basis for the physically appealing concept of regarding the perturbation due to the projectile as having a position-dependent effective frequency associated with it. The result is extended to higher energies with the use of the concept of a local kinetic energy. With a semiclassical approximation the result reduces to a simple general form that should be useful for model potential studies of electron-atom and electron-molecule scattering. Alternatively, variational functionals for the susceptibilities can be used to calculate the approximate optical potential most rigorously without making effective-frequency, average-kinetic-energy, or semiclassical approximations. Intermediate levels of rigor are also possible

A measure of localization properties of one-dimensional single electron lattice systems

International Nuclear Information System (INIS)

Gong, Longyan; Li, Wenjia; Zhao, Shengmei; Cheng, Weiwen

2016-01-01

We propose a novel quantity to measure the degree of localization properties of various types of one-dimension single electron states. The quantity includes information about the spatial variation of probability density of quantum states. Numerical results show that it can distinguish localized states from delocalized ones, so it can be used as a fruitful index to monitor the localization–delocalization transition. Comparing with existing measures, such as geometric average density of states, inverse participation ratio, and quantum information entropies, our proposed quantity has some advantages over them. - Highlights: • A novel quantity is proposed to measure the degree of localization. • It includes information about the spatial variation of probability density. • It is a fruitful index to monitor the localization–delocalization transition.

Lysosomes are associated with microtubules and not with intermediate filaments in cultured fibroblasts.